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for example, by an electron beam in a cathode ray tube or by ultra-violet radiation in a fluorescent lamp. photo diode A basic element that responds to light energy in a solid-state imaging system. It generates an electric current that is proportional to the intensity of the light falling on it. picture-in-picture PIP. A video display mode in which a small video image is superimposed on a quadrant or smaller area of a video screen. This small image or "window" can be opened in order to display a second video input on a monitor. This is a particularly valuable feature in a single monitor videoconferencing system; it allows the near-end to view themselves in a small window while simultaneously seeing the far end. Picturephone AT&T's video-telephone that was introduced at the 1964 World's Fair in Flushing Meadow, New York. The device incorporated a camera that was mounted on top of a 5.25" X 4.75" screen. Since audio signals were transmitted separately from video signals, the system required a transmission bandwidth of 6.3 Mbps and, therefore, could not use the PSTN. It never became popular. pixel The smallest element of a raster display. A picture cell with specific color and/or brightness. Point of presence. Typically the closest location of a carrier to a subscriber and the point at which that subscriber will be supplied with service from that carrier. A multi-wire input/output to a computer or other electronic component. The number of ports determines the number of simultaneous users, the number of peripheral devices one can simultaneously connect with, or a combination of both. Plain Old Telephone Service. Analog narrowband telecommunications service designed for transmitting voice calls. prediction A type of motion compensation in which a compressed frame of video is reconstructed by a receiving codec by Glossary of Terms comparing it to a preceding frame of video and making assumptions about what it should be. Presence Ability to identify the location of a communication recipient and the type of device that

recipient might be using at a given moment (e.g., landline phone, mobile phone, or desktop computer). The ISDN Primary Rate Interface. In the US the PRI consists of 23 64 Kbps bearer or "B" channels and one 64 Kbps delta or "D" channel. In Europe, the PRI- equivalent is known as Primary Rate Access or PRA. The PRA consists of 30 64 Kbps B channels and two 64 Kbps D channels. prism Crystalline bodies with lateral faces that meet at edges that are parallel to each other. A prism is used to refract light, often dispersed into component wavelengths. private line A telephone line rented for the exclusive use of a business and which connects two locations on a point- to-point basis. Communications can only be exchanged between these two locations, as opposed to switched services in which calls can be placed to any other addressable location with compatible service. private network A collection of leased, private circuits that link multiple locations of an enterprise or organization. May be used to transmit different combinations of voice, data and video signals between sites over the point-to-point lines that exist between sites. proprietary Systems that use techniques and processes that are closely-guarded trade secrets and which, because of these highly-individual approaches to achieving a result, cannot interoperate with other manufacturers' equipment without a great deal of difficulty. protocol A standard procedure agreed upon by regulating agencies, companies, or standards-setting bodies to regulate transmission and, therefore, to achieve inter- communications between systems or networks. Public Switched Telephone Network. The conventional voice telephony network as provided by Local Exchange Carriers. Video Communication: the Whole Picture Post Telephone and Telegraph company. A generic term for the telephony providers in Europe and other non-US countries. publicroom A commercial facility that offers video communications services for rent. Pronounced "P times 64." Another (early) name for the ITU-T's H.261 codec.

Q-Signal In the NTSC color system, the Q signal represents the chrominance on the green-magenta axis. Q.920 One of the two ITU-T Recommendations in which the Link Access Protocol-D (LAPD) is formally specified. Q.921 Along with Q.920, this ITU-T Recommendation specifies the LAPD protocol, an OSI layer-2 protocol. The connection-oriented service establishes a point-to-point D channel link between a customer and a carrier's switch. Data is sent over the link as Q.921 packets. Q.931 Whereas the D channel is packet-switched, B channels are circuit-switched. They are established, maintained and torn down using ITU-T Recommendation Q.931 (also known as ITU-T I.451). In Q.931, the ITU-T specified how 'H' channels-multiple contiguous channels on T-1 or E-1/CEPT frames-can be bound together and switched across an ISDN network. Quarter Common Intermediate Format, a mandatory part of the ITU-T H.261 compression standard that requires that non-interlaced frames of NTSC video be sent with 144 luminance lines and 176 pixels. When operating in the QCIF mode the number of bits that result from encoding a single image cannot exceed 64 K bits where K equals 1024. Quality of Service (QoS) defines a level of performance in a communications network. For example, video traffic requires low delay and jitter; data traffic does not, but will burst and thereby impede the transmission of voice traffic. Any channel that transports both must, therefore, reserve and execute preferential treatment for video. Glossary of Terms quality reduction One way of compressing data in which some compromises are made in picture resolution, frame rate and image size in order to accommodate the bandwidth available for transmission. quantization Quantization is one step in the process of converting an analog event into its digital representation. It involves the division of a continuous range of signal values into contiguous parts, a unique value being assigned to each part. Prior to quantization the signal is sampled at regular intervals (typically at a ra

te that is least twice its highest frequency). The instantaneous amplitude of each sample is expressed as one of a defined number of discrete levels. These levels can then be assigned a digital value. quantization matrix A set of values used by a de-quantizer. The H.261 quantization matrix specifies 64 8-bit values. QuickTime Apple's video compression solution developed for the Macintosh product line. Decompression can be accomplished using nothing more than standard computer hardware although QuickTime accelerator cards with hardware decompression chips allows much better results. See random access memory. Random Access Memory RAM. A storage receptacle that is volatile, i.e., that it only retains information until a computer is turned off. raster The pattern of horizontal lines that form the image scanning of a television system. raster scan The process of continually scanning both vertically and horizontally using an electron beam to create moving images on a television screen. Regional Bell Operating Company. This term is used in a general sense today to refer to any of the original 22 Bell Operating Companies that were spun off parent AT&T as part of the MFJ (pronounced R-BOK). Radio Corporation of America. First large commercial enterprise to wholeheartedly pursue television in the Video Communication: the Whole Picture US under the direction of David Sarnoff. RCA Jack A physical interface commonly used in audio and video equipment (often colored red, white, or yellow). Real-time The time that elapses when events occur naturally. This term describes computing and electronic applications in which there is no perceived delay in the transmission of an interactive communication. Real-time compression Capture and compression of video in one step SO that it can be written to disk or other storage media. Real-Time Transport RTP adds a layer to IP to address problems caused Protocol when interactive multimedia communications are transported over TCP/IP networks. Packet-switched networks were designed for data in whi

ch latency is tolerable. In voice and video communications, a constant bit rate is required for smooth delivery. RTP's approach is to give low-latency connection-oriented communications a higher priority than connectionless data. RTP also addresses the need for multicasting and compression over the Internet and other TCP/IP-based networks. TCP is a reliable transport, but its efforts on behalf of reliability are not ideal for video communications. TCP re-sends packets of data that have not been properly received. In video communications, packets that do not arrive on time are no longer useful. RTP does not resend missed packets, but notifies a server that a packet was missed. If the missed packets threshold reaches a specified level, RTP can request additional bandwidth allocation. redundant In the context of compression, redundant information is that which does not change over time (temporal) or space (spatial). Temporal redundancy manifests in a sequence of video frames in which successive frames contain the same information as those that preceded them. This information is, thus, redundant; e.g., not necessary to convey. Rather, it is only necessary to convey the areas of the frame that didchange for that information is critical to the recipient's accurate interpretation of the new frame. Spatial redundancy manifests within a frame of video in which a group of Glossary of Terms similar pixels are clustered. The goal of video compression is to eliminate redundancy that, in turn, reduces the data rate required for transmission. reference frames In video compression reference or intra-coded frames are sent periodically to eliminate the accumulated errors generated through the process of interframe coding. refresh To recharge the cells of a volatile digital memory SO that their contents are not lost. Alternately, to "paint" a new picture on the screen of a VDT is to refresh the screen. repeater A device used to reprocess and amplify a weak signal in a transmission system. Used where the distance between the sender

and receiver is too great for the signal to travel between the two without being boosted along the way. Radio signals, as they travel through free space, are attenuated; their power is gradually lost. Thus repeaters are needed to interpret the original signal and amplify it. They also often amplify background noise and interference in the process. reproducing spot In television broadcasting, images are sent as a series of signals that describe a series of scan lines. A black and white television receiver captures these signals and reproduces the image on the screen using a reproducing spotthat writes to the screen, varying in intensity in accordance with the instantaneous amplitude variations of the received signal. Request in Progress H.323v3 feature that allows the receiver of a request to Message specify, when a message can not be processed before the initial timeout value expires, that a new timeout value should be applied. resolution The ability of an optical or video system to produce separate images of objects very close together and, hence, to reproduce fine detail. retrace The return of an electron beam to its starting place to prepare for sending a new field of information. retrace interval The process of moving a scan line back to the left-most position in order to begin a new scan. Video Communication: the Whole Picture Radio frequency. Electromagnetic signals that travel from radios or other sources through free space. A designator used to name one of the color signals in the color difference video signal, with a formula of .70R, -.59G, -11G. Radio frequency interference. Often manifests in television signals as vertical bars moving slowly across a picture. It can also take the form of diagonal or vertical lines or a pattern of horizontal bars. Red, green, blue. Color television signals are oriented as three separate pictures: red, green, and blue. Systems can merge them or, for maximum quality, leave segregated as component video signals. See Router Information Protocol See Request in Progress Messa

(network layer). A router responds to packets addressed to it by either a terminal or another router. Routers move packets over a specific path or paths based on the packet's destination, network congestion and the protocols implemented on the network. Routing Information Hop-count based interior gateway routing protocol. Protocol RIP is one of the oldest and, perhaps, still the most prevalent routing protocol. RS-170A A specification for adding color to the NTSC television signal. It uses the YIQ method to add hue and Glossary of Terms saturation to a luminance subcarrier. RS-232-C An EIA interchange specification specifying electrical characteristics and pin allocations in a 25-pin connection cable. The equivalent of the international V24 standard. RS-366 An EIA interface standard for autodialing. RS-449 A physical layer specification that defines a 37-pin data connector designed for high-speed transmissions. The signal pairs are balanced and each signal pin has its own return line instead of a common ground. Resource-Reservation Protocol. An IETF specification that allows users of conferencing over the Internet to reserve bandwidth at a given time. Real-Time Transport Control Protocol. A companion to RTP that will allow users to provide feedback on how an RTP session is working; how well packets are being delivered, etc. See Real-Time Transport Protocol. rubber bandwidth Coined by I-MUX manufacturer Ascend, the term refers to an ability to support applications that require varying speeds by dividing a signal up into 56- or 64- Kbps chunks and sending them over a switched digital network. run-length encoding Compression method that works at the bit level to reduce the number of repeating bits in a file. Sending only one example, followed by a shorthand description of the number of times it repeats, indicates a string of identical bits. S-Video Super Video (as opposed to composite). S-Video is a hardware standard that defines the physical cable jack used for video connections. The connector takes the form of a 4

-pin mini plug when separate channels are provided for luminance and chrominance. Also known as Y/C Video, S-Video is used in the S-VHS and Hi8 videotape formats. sampling The process of measuring an analog signal in time Video Communication: the Whole Picture slices SO that it can be quantized and encoded in a digital format. The sampling interval, per Nyquist's Theorem, must be at least twice the highest frequency contained in the analog input. Thus, in an analog signal in which frequencies of 4,000 hertz are possible, the sampling rate must be 8,000 per second. satellite A man-made object designed to orbit the earth. Used to receive and retransmit telecommunications signals that originate at an earth station. satellite delay In satellite transmissions a signal must travel from the earth to a transponder placed in geosynchronous orbit, a distance of 22,300 miles above the equator. Radio waves, which travel at approximately the speed of light (186,000 miles per second) take about.24 seconds to make the round trip, and thereby induce perceptible delay in satellite communications that are particularly annoying in speech and interactive video. transmissions. satellite receiver A microwave antenna that is capable of intercepting satellite transmitted signals, lowering the frequency of those signals and retrieving the modulated information. saturation In color reproduction, the spectral purity or intensity of a color. Adding white to a hue reduces its saturation. A three-bit integer that indicates the number of bits that should be ignored in the first data octet of a RTP H.261 packet. scan converter A device that converts computer images to a television display format. Used to convert the scan rates of VGA or SVGA to NTSC, PAL or SECAM scan rates. scan line During scanning, a number of nearly horizontal passes are made across an image and the light recorded by the image is converted into an electrical signal. Each pass across the image is called a scan line. scanner A device used to capture and digitize images. A sca

nner reads the light and dark areas of an image and converts the light into a coded signal. scanning The process of analyzing the brightness and colors of an image, using a camera or other collection device, Glossary of Terms according to a predetermined pattern. In monitors, the number of scanning lines per frame gives an indication of the quality of the picture transmitted and displayed. Super CIF. A standard video exchange format made up of a square of four CIF images. SCIF specifies 576 lines, each of which contains 704 pixels. Also known as 4CIF. screen Devices that emit or reflect light to a viewer. Examples include the silver sheets of beaded vinyl upon which motion pictures or slides are projected, conventional CRTs, LCD displays, and conventional televisions. See Session Description Protocol. SECAM Sequential Couleur Avec Memoire. The color television system that offers 625 scan lines and 25 interlaced frames per second. It was developed after NTSC and PAL and is used in France, the former Soviet Union, the former Eastern bloc countries and parts of the Middle East. Two versions of SECAM exist: horizontal SECAM and vertical SECAM. In this system, frequency modulation is used to encode the chrominance signal. Security policy An information security policy as an explicit set of prescribed practices that fosters protection of the enterprise network and of information assets. security video Video systems that are used to observe the events in a distant location, nearly always in a receive-only arrangement. Many such systems are slow-scan and use inexpensive cameras to capture images. The video signal. Typically not digitized or compressed. serial communication Used to connect computers with modems, printers and networks. Networks based on serial communication typically use the EIA's RS-232-C interface in which the pins that carry the electrical signal are arranged in a pattern that is understood by both the sending and receiving device. serial interface Refers to data being transferred between a computer and

some type of peripheral device, often a printer, in a series of bits in which each bit is sent one at a time as part of a sequence. Video Communication: the Whole Picture server In a network, a server is the device that host applications and allocates the activities of shared support resources. Servers store applications, files, and databases; they provide access to printers and fax machines, and they permit clients to access external communications networks and information systems. Session Description Associated with SIP, SDP is a Protocol for conveying Protocol information about streams in multimedia sessions to enable recipients of a session description to participate in a session. In a Multicast session, SDP is a means to communicate the timing and existence of a session, and to convey sufficient information to enable recipients to join and participate in the session. Session Initiation Protocol Defined in IETF RFC 2543, SIP is an application-layer control (signaling) protocol for creating, modifying, and terminating sessions with one or more participants. Sessions can be Internet multimedia conferences, Internet telephone calls, or multimedia distribution. Members in a session can communicate via multicast, a mesh of unicast relations, or a combination of these. set-top box In a CATV environment, the cable terminates in the subscriber's location on a decoder or set-top box, which is connected directly to the television receiver. Set-tops vary greatly in complexity. Older models merely translate the frequency received off the cable into a frequency suitable for the television receiver; newer models are addressable and offer a unique identity much like a telephone. Interactive set-tops allow subscribers to communicate interactively. seven-layer model See OSI (Open Systems Interconnection) model. shadow mask In a color monitor, this component is placed between the electron guns and the screen to ensure that the electron beams are restricted to their targeted dots. shutter A device that cuts off light in an opt

ical instrument. Source input format. Used in MPEG, and not to be confused with the Common Intermediate Format (CIF) used in the ITU-T's H.32X family of videoconferencing standards. Glossary of Terms signal-to-noise A ratio used to describe the clarity or degradation of a circuit. Signal-to-noise is measured in decibels. An acceptable signal-to-noise ratio is generally 200:1 or 46 See Session Initiation Protocol. simplex A circuit capable of transmissions in only one direction. sine wave The smooth, symmetrical curve that is created by natural vibrations that occur in the universe. single mode fiber Optical fiber with a central core of such small dimension that only a single mode of transmission is possible. Light travels straight down the middle of the fiber without zigzagging from side to side. Single mode fibers transmit high bit rates over long distances. slow-scan Television or video scanning system in which a frame rate lower than normal is used to reduce the bandwidth required for transmission. Often associated with the transmission of video frames over the public switched telephone network. SMATV Satellite Master Antenna Television. A distribution system that feeds satellite signals to hotels, apartments, etc. Often associated with pay-per-view. Switched Multimegabit Digital Service. A public networking service based on the IEEE's 802.6 specification. smear The undesirable blurring of edges in a compressed image, often caused by the DCT that tends to eliminate the high-frequency portions of an image that represent sharp edges. SMPTE Society of Motion Picture and Television Engineers, the authors of the SMPTE time code used in video film and A/V production. SMPTE Time Code An 80-bit time code used in video editing. Developed by the SMPTE. Random noise or interference appearing in a video picture as white specs. Video Communication: the Whole Picture software The programs, procedures, rules and routines used to extend the capabilities of computers. SONET Synchronous Optical Network. sound waves Naturally oc

curring oscillations that are created when objects vibrate at a certain frequency, and thereby compress the air molecules around them and cause these molecules to seek equilibrium by decompressing outward. During decompression dynamic energy is expended, thereby causing neighboring groups of molecules to compress. This starts a chain reaction. Compressed air is pushed in all directions from the source. If the resulting waves are between 50 and 20,000 Hz humans can hear them as sounds. spatial Compression/coding that is performed on a single frame of video data as opposed to temporal (time) coding that is performed by comparing successive video frames to each other. spectrum A range of wavelengths or frequencies of acoustic, visible or electromagnetic radiation. Also refers to a display of visible light radiation that is arranged in order of wavelength. SpectrumSaver Compression Labs compression system designed to digitize and compress a full-motion NTSC or PAL analog TV signal SO that it can be transmitted via satellite in as little as 2 MHz of bandwidth. splitter In CATV networks, multiple feeder cables are attached to splitters that match the impedance of the cables. square wave A term typically used to refer to a digital signal comprised of only two voltage values, that represent on and off (or one and zero). SQCIF H.263, a scalable version of H.261, Sub-QCIF, a 128- by-96 pixel image resolution format. SQCIF was also added to the H.261 recommendation, to allow low- resolution picture coding. S/T-Interface The ISDN Subscriber/Termination (S/T) Interface uses two pairs of wires to deliver an ISDN signal from a wall jack to an ISDN adapter or other ISDN equipment. standards conversion The process of adapting a television or video production from one set of standards (e.g., NTSC) to Glossary of Terms another (e.g., PAL). This is necessary when programming that was developed for one part of the world (e.g., North America), is viewed in another (e.g., Europe). star topology A network in which there is an individual

connection between a switching point (or in the CATV world, a head-end) and a device or subscriber. store-and-forward Systems in which messages (including video-enabled messages) are stored at an intermediate point for later retrieval. streaking In video, shifting brightness across an image at the vertical location of a bright object. streaming data Any transmission with a time component, such as video and audio signals. Study Group Groups of subject experts that are appointed by the ITU-T, an international standards-setting body that is part of the United Nations. Study Groups draw up Recommendations that are submitted to the ITU-T at the next plenary assembly for adoption. subcarrier A band of frequencies superimposed onto a main carrier frequency. In color television the color information is carried on the same subcarrier as the luminance signal by modulating it onto the upper frequencies of the luma waveform. subjective evaluation During the process of comparing videoconferencing systems, the portion of the comparison that is in the eye-of-the-beholder as opposed to being quantifiable. subscriber A customer of a carrier, service provider or utility. subtractive color Color information that results from reflection or refraction of light. Reflected wavelengths correspond to the colors that people attribute to those objects. The subtractive primaries are magenta, cyan, and yellow. In contrast, additive color results from wavelengths of radiation emitted by light sources. Additive primaries are red, blue and green (RGB). Super CIF A video format defined in the 1992 Annex IV amendment of the ITU-T's H.261 coding standard. Also known as 4CIF in the ITU-T's H.263 standard, it Video Communication: the Whole Picture is comprised of 704 by 576 pixels. super trunks Large diameter coaxial or fiber-optic cables used to carry a signal from a head-end to various hub sites in a CATV network. Super VGA SVGA. A higher resolution version of the VGA standard that allows applications to use video resolutions of 1,024-by-768 pixe

ls. switch A device that establishes, monitors, and terminates a connection between devices connected to a network. Switched 56 Switched 56 is a legacy service that enables dialing and transmitting of digital information up to 56 Kbps in a manner similar to placing an analog telephone call. The service is billed like a voice line-a monthly charge plus a cost for each minute of usage. Any switched 56 offering can connect with any other offering, regardless of carrier. switching The process of establishing a connection between an input and an output. Switching occurs in many parts of a network, such as at a PBX, at the local exchange, at an IXC's office, or in X.25 or frame relay networks. It allows a subscriber to establish communication with multiple parties by sending an address to the switch which, in turn, attempts to make a connection. switching hub See Ethernet Switch symmetrical Techniques in which the decompression techniques are an exact reverse of the compression techniques. Used in Real-Time interactive video applications. synchpulse Oscillator circuits generate the horizontal and vertical sweep signals in a television receiver; they are controlled, in precise synchrony, by the movement of the scanning element at the camera. To achieve horizontal control, the camera sends synch pulses along with the luminance information. To control the vertical sweep oscillator, a synch pulse is sent at the end of each field. synchronization The process of controlling two or more systems SO that they establish a time-based relationship with each other. Clocks are used to ensure precision in the sending and receiving of bits or other signals; Glossary of Terms characters are spaced by time, not bits. system bus Analogous to the nervous system in the human body, the system bus serves to interconnect the microprocessor with memory, storage devices, and input/output hardware. Also known as DS-1 or T-carrier. High-speed digital transmission system characterized by a bit rate of 1.544 Mbps and subdivided, via time division m

ultiplexing, into 24 channels. Each channel has a bit rate of 64 Kbps. Frames of data are created 8,000 times a second by combining each channel's 8-bit time slot into a group of 192 bits, a synchronization bit is added to the frame that makes it 193 bits wide. These 193-bit frames are sent 8,000 times a second and received by a channel bank or T-1 multiplexer. T.120 The ITU-T's "Transmission Protocols for Multimedia Data," a data sharing/data conferencing specification that lets users share documents during any H.32x videoconference. Like H.32x specifications, T.120 is an umbrella Recommendation that includes a number of other Recommendations Data-only T.120 sessions can be held when no video communications are required, and the standard also allows multipoint meetings that include participants using different transmission media. The mandatory components of T.120 include recommendations for multipoint file transfer and shared-whiteboard implementation. T.121 The T.120 family member that is formally known as "Generic Application Template." This template encompasses those operations that are common to most T.120 application protocols. T.122 ITU-T Recommendation that is part of the T.120 family and which is known as "Multipoint Communication Service for Audiographics and Audiovisual Conferencing Service Definition." T.122 defines the multipoint services available to an applications developer while T.125 specifies the data Video Communication: the Whole Picture protocol used to implement these services. T.123 ITU-T Recommendation that is part of the T.120 family and which is known as "Protocol Stacks for Audiographic and Audiovisual Teleconference Applications." This protocol covers public switched telephone networks, ISDN, circuit switched digital networks, packet-switched digital networks, Novell NetWare IPX (via a reference profile) and TCP/IP. T.124 ITU-T Recommendation that is part of the T.120 family and which is known as that allows "Generic Conference Control." T.125 ITU-T Recommendation that is part of the

T.120 family and which is known as "Multipoint Communication Service Protocol Specification." T.126 ITU-T Recommendation that is part of the T.120 family and which is known as "Multipoint Still Image and Annotation Protocol." This standard defines a protocol for annotated shared whiteboard applications and still image conferencing. It uses services provided by T.122 and T.124. Remote pointing and keyboard data exchanges are covered, and therefore allow terminals to share applications, even if they are running on different platforms or operating systems. T.127 ITU-T Recommendation that is part of the T.120 family and which is known as "Multipoint Binary File Transfer Protocol." This allows participants in an interactive data conference to exchange binary files, and provides a means to distribute and retrieve one or more such files simultaneously. T.128 T.128 - Audio Visual Control for Multipoint Multimedia Systems. Now replaced with the T.130 family of ITU-T Draft Recommendations T.130 The ITU-T's Draft Recommendation for "Real Time Architecture for Multimedia Conferencing. Provides an overview of how T.120 data conferencing will work in conjunction with H.32x videoconferencing. T.131 The ITU-T's Draft Recommendation for "Network- Specific Mappings." Defines how Real-Time audio and video streams should be carried over different types of networks including B-ISDN and ATM when used in Glossary of Terms conjunction with T.120 data conferencing. T.132 The ITU-T's Draft Recommendation for "Real Time Link Management." Defines how real time audiovisual streams can be routed between diverse multimedia endpoints. T.133 The ITU-T's Draft Recommendation for "Audio Visual Control Services." Defines how to control the source and link devices associated with real time information streams. ISO-JPEG standard. T.RES The ITU-T's Draft Recommendation for "Reservation Services." Defines how terminals, MCUs and reservations systems will interact to reserve a conference. Part of the T.130 family. T.TUD The ITU-T's Draft Recommendation

for "User Reservation." Describes how to transport user defined bit streams between conferencing end-points. Part of the T.130 family. See DS-3. talking head The portion of a person that can be seen in the typical business-meeting-style videoconference; the head and shoulders. Because there is little motion in a talking head image (most is in facial expression) it is easy to capture with compressed video. In CATV systems the subscriber drop connects to feeder cables via taps; passive devices that isolate the feeder cable from the drop. tariff The terms and conditions of telecommunications or transmission service. Tariffs generally require approval by a regulatory body such as the FCC, PUCs or Often (UK). TCP/IP Transmission Control Protocol/Internet Protocol. A de facto standard and a set of internetworking protocols originally developed by the Department of Defense. Connects dissimilar computers across networks and is, therefore, widely used in the private sector. TCP/IP protocols work in the third and fourth layers of the OSI model to guarantee the delivery of data even in Video Communication: the Whole Picture very congested networks. Time Division Multiplexing. A technique for interleaving multiple voice, data and video signals onto a single carrier by assigning each signal its own separate time slot during which it can place a segment of its digitally-encoded transmission. At the distant end, the signals are separated SO that each discrete signal can be re-oriented and recombined as an entire communication or message. Telco A generic name generally used to refer to local exchange carriers; telephone companies providing local exchange service. telecommunications The art and science of applying services and technologies in order to enable communications over distance. Uses technologies such as radio, terrestrial and cable-based services, wireless transmission and optical fiber networks. Telecommunications Passed by the 104th Congress and signed by President Competition and Clinton in February, 1996, the Teleco

mmunications Deregulation Act of 1996 Competition and Deregulation Act of 1996 was a rewrite of the Communications Act of 1934. The stated goal of the act was to promote competition and reduce regulation to secure lower prices and higher quality, more robust, services for American telecommunications consumers by encouraging the rapid deployment of new telecommunications technologies. telecommuting The process of commuting to work electronically rather than physically. teleconferencing The use of telecommunications links to provide audio or audio/video/graphics capabilities. These systems allow distant workgroups or individuals to meet, and thereby reduce the administrative and opportunity costs of holding in-person meetings involving people from many different cities or countries. telemedicine The practice of using videoconferencing technologies to diagnose illness and provide medical treatment over a distance. Used in rural areas where health care is not readily available and to provide medical services to prisoners, among other applications. Glossary of Terms telephony The convergence of telephone and computer functionality. Specifically, the process of converting voice and other sounds into electrical signals that can be transmitted by wire, radio or fiber; stored and reconverted to audio upon receipt at the distant end. telewriting-based terminal An older term that refers to devices that use digitizing equipment tablets and monitors to enable the sharing of text and graphics in video- and teleconferences. These devices were more evident in the very early 1990s. They used voice-grade circuits or required low data rates for transmission, typically about 9.6 Kbps. They were the predecessor to document conferencing systems. temporal coding Compression that is achieved by comparing successive frames of video over time to eliminate redundancies between them. See tiling. An individual pixel block that becomes visible on the viewer's monitor. Tiles, together, appear as a series of mosaic squares. tiling Video effect

in which the image appears as pixel blocks. Can be caused by compression when the sampling rate or bandwidth is not adequate to fully describe the original image. time-division multiplexing A way of enabling a single bearer signal to carry more than one information channel simultaneously. This is achieved by sharing the common transmission path on a cyclical basis. Each channel takes a turn using the path by entering the source data into a "time slot." Common TDM systems can support 24 channels in the US and 32 in Europe. time slot In TDM or TDSW, the slice of time that belongs to a digitized communication whether it be voice, data or video communication. transcoding Conversion from one format to another. This may be from one digital format into another, or between dissimilar formats such as from digital frames into analog video or from text into speech. transform coding A technique of video compression that requires VLSI chips with hundreds of thousands of gates. See DCT for a description of one type of transform coding. Video Communication: the Whole Picture TransMux MPEG-4 specifies an interface to the TransMux (Transport Multiplexing) models, the layer that offers transport services for matching the requested QoS. Any suitable existing transport protocol stack (e.g., RTP in UDP/IP, AAL5 in ATM, or Transport Stream in MPEG-2) over a suitable link layer may become a specific TransMux instance. transponder A microwave repeater mounted on a satellite and used to receive communication from an uplink and retransmit it at a different frequency on a downlink. tree and branch A cable television arrangement in which large capacity cables called super trunks radiate from the head-end to various sectors of the franchise area to hub sites. From these hub sites, lower-capacity cables branch out into the surrounding districts to be split and split again until cable runs along every street. A tapping point outside each residence enables the final connection to the residence. tuner A piece of equipment or portion of a circuit

used to select one signal or channel from amongst many signals or channels. twisted pair Two insulated copper wires twisted at regular intervals and normally covered by a protective outer sheath composed of PVC. U-Interface The U-Interface carries ISDN formatted signals over a single pair of wires between a subscriber's location and a telephone company's central office. User datagram protocol; an unreliable connectionless transport protocol that sends un-sequenced packets across a packet-switched network. UDP is defined in RFC 768. Ultra High Frequency. The spectrum band that occupies frequencies from 470 to 890 MHz, within which television channels 14 through 83, are transmitted. CATV systems cannot transport these frequencies SO they are converted for the purposes of cable transmission. Glossary of Terms User Location Service. A white-pages directory that allows users of Internet videoconferencing and personal conferencing tools to refresh IP addresses dynamically and to determine who is logged on and available to have a conference. unicast Application of conferencing, usually over packet- switched networks, where only one user or site receives data. Contrast this with multicast in which data is received by more than one user or site. up-link The portion of a communications link used for the transmission of signals from a satellite earth station to satellite transponders in space. upstream transmission The ability for a CATV subscriber to communicate interactively with the head-end or a hub-site. Universal Serial Bus is a hardware interface for peripherals such as keyboards, mice, scanners, and telephony devices. USB supports MPEG-1 and MPEG- 2 digital video. USB allows for 1-127 attached devices, and allows devices to use its full 12 Mbps bandwidth or a 1.5 Mbps subchannel (it also allows for hot- swapping). Low-power devices that might normally require a separate AC adapter can be powered through the cable because the USB bus distributes 0.5 amps of power through each port. Unshielded Twisted Pair. An ITU-T

standard interface between a network access device and a network. An ITU-T list of interchange circuits for connecting a terminal device to a modem or one type of communications equipment to another. Videocassette recorder-originally a trade name but now a generic term commonly used for a device that plays videotapes. Very-high-speed-digital subscriber line. vector quantization A vector is a mathematical representation of a force (in video the force is a frequency, or a series of Video Communication: the Whole Picture frequencies). In vector quantization blocks of pixels are analyzed to determine their vectors. Vectors are then used to select predefined equations that describe them in a more efficient way. These equations are expressed as codes, which might be only a few bits long. A decoder interprets these abbreviated codes and uses them to describe a frequency with a given hue and saturation. vertical blanking An interval that occurs at the beginning of each video field in which the reproducing spot is turned off during the process of retracing from the bottom right to the top left of the screen. After the vertical blanking period has ended the electron starts shooting electrons at the screen again, starting at the top and working toward the bottom. vertical resolution The total number of horizontal scan lines. vertical sweep signal The electrical signal that moves each horizontal scan line vertically. Video Graphics Array. Developed by IBM, this has become the dominant standard for PC graphics. VGA provides two different graphics modes: 640 by 480 pixels at 4-bits per pixel or 320 by 200 pixels where 8 bits are used to describe a pixel. Very High Frequency. The frequency band used to transmit television channels two through 13. video A sequence of still images that, when presented at a sufficiently high frame rate, give the illusion of fluid motion. In the US, full-motion video (TV) is sent at 30 frames per second In Europe and most of the rest of the world the frame rate is 25 per second. Motion pictures sen

d video at 24 frames per second. video capture board A PC circuit board that can capture the two fields that comprise a single video frame (included in most modern PCs). See also frame grabber. video mail A multimedia version of electronic mail that includes moving or still images that are embedded into the message. Also known as v-mail. video server A specialized file server with enormous hard disc capacities (often measured in terabytes or trillions of Glossary of Terms bytes). A video server stores compressed audio and video images for access. Often called video jukeboxes, these servers provide service to end-users over high- speed networks. video wall Multi-screen video system in which a large number of video monitors or back projection modules together produce one big, bright image. This is achieved by splitting the incoming video signal across many monitors. Video-On-Demand VOD. The ability for subscribers to control when and how they view a movie. VOD delivers features that mimic VCRs (e.g., rewind, pause, fast-forward(. videoconferencing A collection of technologies that integrate video with audio, data, or both and convey the aggregate signal, Real-Time, over distance for the purposes of a meeting between dispersed sites. videophones Telephones with video capability. virtual circuit A seemingly dedicated connection between two points in a packet-switched network. In a virtual circuit, packetized data from multiple devices is placed on the same circuit. virtual private network Virtual private network technology allows an organization to use the Internet as a private network by employing tunneling or data encryption techniques in a firewall. Very Large Scale Integration. voice-activated Microphones that automatically capture and transmit microphones audio at the trigger of a voice. Transmission ceases when the triggering sound stops. Videoconferencing system manufacturers effectively incorporate voice- activated microphones with cameras that capture and transmit images based on who is speaking. voltage Ele

ctrical pressure caused by electrons repelling other electrons. Very Small Aperture Terminals. Small transportable satellite earth stations used in videoconferencing BTV applications. VTS 1.5 Compression Lab's first codec that was introduced in Video Communication: the Whole Picture 1982. It had an operating bandwidth requirement of 1.544 Mbps (T-1), remarkable for the time. watts A measure of the power or electrical energy of a signal or waveform. wavelength division A technology that uses lasers to transmit multiple light multiplexing signals concurrently over a single optical fiber. With WDM, each signal travels within its own color band and is modulated by transmitted data. waveform A presentation of the varying amplitude of a signal in relation to time. See Wavelength Division Multiplexing white balance A camera feature that adjusts the balance between the RGB components that yields white in the video signal. Cool-temperature lighting casts a different tint on a room than does warm-temperature lighting. White balance produces a uniform white regardless of room lighting. white noise Noise, containing energy, distributed uniformly over the frequency spectrum. whiteboarding The ability for multiple users to share a drawing space, generally a bit-mapped image that all conferees can modify. wide area network WAN, a collection of circuits that make up the public switched network and over which organizations communicate. Used primarily in Europe, X.21 is a standard that operates at bit rates between 56 Kbps and 384 Kbps to control network dialing. A valuable feature of X.21 is its inherent dialing functions, including the provision for reporting why a call did not complete. X.21 can be used to connect to both switched and dedicated networks. Glossary of Terms The common nomenclature for the luminance signal. In component video, the Y or luminance signal is kept separate from the C (hue and color saturation signal) to allow greater control and to enable enhanced quality images. The luminance is recorded at a higher

frequency and therefore more resolution lines are available. Super-VHS and Hi8 systems use Y/C video. YCbCr This term refers to the three different components that make up component video. Y represents the luminance portion of the signal. Cb and Cr represent the two different chroma components. CCIR-601 specifies 8- bit encoding for component video. White is luma code 235. Black is luma code 16. A trichromatic color system used in NTSC color television systems. The luminance signal is the Y signal. There are two elements of color, hue and saturation. The color information is modulated onto the subcarrier with the phase of the sine wave describing the color itself and the amplitude describing the level of color saturation. Y uses 4.5 MHz, I uses 1.5 MHz and 1 uses 0.5 MHz. YPbPr Part of the CCIR Rec. 709 HDTV standard that refers to three components (luma and two color components) that are conveyed in three separate channels with identical unity excursions. YPbPr is employed by component analog video equipment such as M-II and Betacam. In YPbPr, Pb equals (0.5/0.886) multiplied by Bgamma minus Y. Pr equals (0.5/0.701) multiplied by Rgamma minus Y. The complete set of component signals, that comprise luminance (Y) and the two color difference signals, U (B-Y) and V (R-Y). Zigzag scanning Used in the Discrete Cosine Transform, zigzag scanning results in the reordering of DCT coefficients from the lowest spatial frequency to the highest. Since Video Communication: the Whole Picture the highest spatial frequencies have values that tend toward zero, reordering them through zigzag scanning results in long strings of zeros that can be abbreviated using run-length encoding. INDEX 1996 Olympics application sharing, 292 telecommuting, 23 applications sharing / document collaboration, 303 3COM, 232 3-D, 307 applications suites, 294 802.14, 216, 217, 441 Asymmetrical Digital Subscriber Line, 389 Aboriginal Asynchronous Transfer Mode (ATM), 13, Tanami Network, 45 absorption loss, 387 failure to provide carrier gateways, 196 ac

oustic echo return loss enhancement four-wire switched 56 INC USDC, 200 (AERLE) ratings, 255 HO service, 207 ActiveX, 299 Aetna Life and Casualty H11 service, 207 early adopter of videoconferencing, 8 introduction of switched 56, 199 Air Products and Chemicals, 24 MFJ, 418, 453 Al Gore Picturephone, 462 Atlantic Richfield distance learning, 32 Alec Reeves early adopter of videoconferencing, 8 PCM, 93 ATM, 181, 209 alternate local exchange carrier (ALEC), 193 support of isochronous service, 211 ATSC, 339 alternating current generator Ernst F. W. Alexanderson, 67 audio algorithms, 252 Audio Video Control ambient noise minimizing in a videoconferencing room Conference Services (T.133), 150 environment, 272 Infrastructure Management (T.132), 149 American Disabilities Act, 58 AudioFX, 355 American National Standards Institute audiographics (ANSI), 337 ratification of standards, 12 amplitude modulation (AM), 67 Audion tube Amtrak Lee De Forrest, 68 video survellance, 29 audio-only meeting participants, 276 Annex D of the H.261 standard, 258 audio-video synchronization, 307 Apple Audio-Video Transport Working Group QuickTime, 465 (IETF), 173 Application Layer (TCP/IP), 170 auditions Video Communication: the Whole Picture over video, 23 boardroom videoconferencing systems, 242 AUSSAT 3 satellite, 45 Boeing, 26 auto focus, 394 early adopter of videoconferencing, 8 automatic gain control (AGC), 375 BONDING automatic mixing techniques standard, 208 for managing multiple microphones, 274 brainstorming, 290, 291 automobile manufacturer Branly, Edouard, 66 virtuall co-location of engineering groups, British Broadcasting Corporation, 397 British Telecom auxiliary cameras, 257, 276 initiation of EVE trial, 112 videoconferencing pioneer, 6 Conference Service Management (T.133), British-Open University, 32 broadband local loop, 294 AVC: Infrastructure Management (T.132), brokering excess videoconferencing room capacity, 285 BancTec, 26 BT North America, 245 Bandwidth On Demand Interoperability Group (BONDING), 208 business case ba

Social Security Administration, 54 Bell Communications Research (Bellcore), soft-dollar benefits, 57 60, 209, 426 trials and demonstrations, 59 Bell Labs, 6, 15, 92, 93, 99, 397, 418 Cable modems, 402 history of videoconferencing, 6 Cable Reregulation Act of 1992, 402 B-frame bi-directional (interpolation) coding conferencing, 26 technique as defined in the MPEG standard, 341 California State University biometric, 315 instructional TV, 32 cameras, 260 B-ISDN, 210 bit plane, 105 camera presets, 257 bit-map, 105 for personal conferencing, 307 Bit-rate Allocation Signal, 121 lenses, 450 bit-robbing, 94 low light conditions, 257 boardroom systems, 246 cancellation charges boardroom videoconferencing levied on users of videoconferencing room services, 285 legacy of, 10 Index carrier, 67 clean-room carriers video into, 22 carrier gateways, 196 CLI, 8, 9, 11, 21, 243, 244, 245, 295, 406, 408 failure of IXCs to connect their digital closed circuit television, 405 networks, 195 CNAME (RTCP), 178 network interface, 278 codec, 7, 8, 9, 10, 11, 44, 93, 97, 98, 99, 100, Cass, Dwight, 147 101, 103, 105, 108, 112, 113, 116, 117, Category 3 UTP, 231 118, 119, 120, 121, 127, 128, 129, 136, 141, 176, 177, 200, 206, 208, 241, 242, CCIR, 336 243, 244, 245, 248, 249, 250, 251, 259, Rec. 601, 347, 405, 414 260, 261, 279, 281, 285, 293, 343, 373, 374, 375, 382, 395, 396, 408, 409, 411, CCIR Rec. 601-2, 336 419, 423, 432, 436, 437, 450, 458, 462, CCIR Rec. 709, 487 464, 468, 485 CCIR Rec. 709 -1, 336 definition of, 7, 93 CCIR-601, 361 Collaboration for Interactive Visual Distance CCITT, 198, 205, 336 Learning (CIVDL), 408 cell relay, 210 color differencing, 84 CellB, 298 color scanners, 260 center clipper, 255 color temperature, 275 color-depth, 307 E1, 94 Columbia Broadcasting System Champion Spark Plug, 33 establishment of, 75 Comité Consultatif International charge coupled device (CCD), 80, 404 Téléphonique des Radiocommunications chat, 306 (CCIR), 336 Chen, Dr. Wen-hsiung Comité Consultatif International CLI founder, 8 Téléphonique

et Télégraphique (CCITT), chrominance, 84, 85, 277 Commission Internationale de l'Eclairage, 78 Cingular, 159, 160, 327, 330 Commission Internationale de l'Eclairage circuit, 407 (CIE), 407 circuit switching, 224, 407 Common Channel Signaling System 7 (SS7), Cisco, 125, 181, 232, 453 Cisco Systems, 125, 232 Common Intermediate Format (CIF), 114 CISSP, i, iv, 313, 407 Communications Act of 1934, 74 Citibank FCC, 190 early adopter of videoconferencing, 8 companding, 106 City Colleges of Chicago, 32 Compaq, 232 Class D addressing competitive access providers (CAPs), 193 in IP multicasting, 184 component video, 96, 277, 487 Clean Air Act, 58 YUV, 277 Video Communication: the Whole Picture composite video, 84 CSU/DSU YIQ encoding, 277 unipolar nonreturn to zero signaling, 195 compressed digital broadcast, 292 custom-engineered videoconferencing Compression, 97 facilities, 269 compression (hardware VS. software), 306 D4 framing, 94 Compression Labs, 408 DARPA, 397 Cameo, 403 early videoconferencing project, 7 Compressed Digital Video, 406 data conferencing Differential Transform Coding (DXC) Microsoft, 141 CLI's early compression technique, 244 feature comparison checklist, 305 early videoconferencing system, 8 data service units (DSU), 420 VTS-1.5, 243 data-conferencing, 290 Compression Labs, Incorporated (CLI), 8 datagrams, 170 Computer aided design DAVIC, 149,216 conferencing, 26 de facto standards, 335 connection-oriented, 224 de jure standards, 335 Conrail Defense Advanced Research Projects Agency use of videoconferencing, 33 early videoconferencing project, 7 Consortium for Audiographics delay synchronization Teleconferencing Standards (CATS), 140 as performed by inverse multiplexers, 208 constant bit rate (CBR) dense mode PIM, 186 needed for videoconferencing, 224 departmental computing, 246 Consultatif International des depth of field, 27, 256 Radiocommunications (CCIR), 111 DES, 218, 416, 423 continuous presence, 127, 261 desktop videoconferencing, 292 continuous surveillance desktop-to-room system videoconfer

encing, case study, 29 control unit, 262 dichroic mirrors, 79 Controlled Delay (RSVP), 180 differences in small-group systems, 246 Controlled Load (RSVP), 180 Diffie-Hellman, 317 convergence time, 255 digital networks COS, 206 Alternate Mark Inversion (AMI), 194 cosine Extended Super Frame (ESF), 194 definition of, 101 Digital sampling COST 211, 112 Harry Nyquist, 92 crisis management digital signal processing (DSP), 251 case study, 23 digital versatile disk (DVD), 344 CSMA/CD, 225 digital video Index encoding, 91 orthicon tube, 78 Digital Video Interactive (DVI) early electronic TV Intel's early video compression scheme, Archibald Campbell-Swinton, 69 early out-of-band signaling direct acoustic coupling, 273 Common Channel Interoffice Signaling Discrete Cosine Transform, 417 (CCIS), 198 Discrete Cosine Transform (DCT) early radio zig-zag scanning, 102 Radio Corporation of America (RCA), 68 Discrete Wavelet Transform (DWT), 417 early TV Distance Learning, 31, 391, 447 2TV, 71 North Slope Borough School District, 41 Bell Labs, 71 Distance Training, 32 Boris Rosing, 69 Distance Vector Multicast Routing Protocol British Broadcasting Company (BBC), 69 (DVMRP), 185 Charles Jenkins, 70 distance-collaboration, 289 David Sarnoff, 73 DMIF, 350, 353, 354, 414, 418 electro-mechanical television, 73 document camera, 262, 280, 282, 373 John Logie Baird, 70 ceiling-mounted systems, 276 National Broadcasting Company, 74 document collaboration products, 291 Philo T. Farnsworth, 73 document conferencing, 12 Phonovision, 72 domain name, 172 three-D color television, 72 Domain Name System (DNS), 171 Westinghouse, 70 Dow Jones Irwin Handbook of early video Telecommunications Management, 56 Alexander Graham Bell, 68 DS-1 signal, 193 Paul Nipkow, image scanning, 69 DS-2, 94 Selenium, 68 DS-3, 94 Earth in the Balance, 32 DSL, 213 echo cancellation, 255, 274 DSM-CC, 149 methods, 274 Duke Power Company echo control, 251 emergency response, 30 echo suppression, 255,273 DVMRP EIA RS-449/422, 278 how it works, 185 Electrical and Electronic

Engineers (IEEE), as a basis for the Px64 compression electromagnetic waves, 65, 66 algorithm, 244 electronic white boards, 276 dynamic channel management, 307 Electronics Industries Association (EIA), 84, early adopters of videoconferencing, 8 200, 230 early camera Video Communication: the Whole Picture encoding, 93 field, 81 David Huffman, 99 field-interlacing, 82 Lempel-Ziv-Welch (LZW), 99 file transfers, 305 encrypting signals for privacy, 263 firewalls (and UDP), 174 encryption, 29, 112, 131, 132, 218, 247, 314, first broadcast of sounds, 67 317, 318, 376, 377, 415, 416, 423, 435, 485 flatbed scanners, 28, 260 Ethernet FlexMux, 350, 427 10Base-T, 226 flight test engineers ability to handle motion video, 305 review tests over video, 22 history of, 225 fluorescent lights LAN microsegmentation, 226 problems caused by, 273 original design criteria, 224 tips for using in a videoconferencing switching hubs, 227 room, 275 European Broadcasting Union, 421 focal length, 256 European HDTV, 414, 452 foot-candle European I.920 specifications, 207 as a measurement of light intensity, 275 European networks, 419 FORE Systems, 232 European PTTs, 278 four-bit gray-scale scanners, 260 European Telecommunications Standards fractal compression, 428 Institute (ETSI), 424 Fractal Image Format, 428 European television standards, 115, 425 fractional T-1 (FT-1), 193 European videoconferencing, 112, 285 frame rates codec manufacturers, 112, 120 NTSC cameras, 249 European Visual Teleconference Experiment FrEdMail (EVE), 112 distance learning on Internet, 32 evaluating monitors Free Educational Electronic Mail dot pitch, 260 distance learning over Internet, 32 EZ-ISDN, 206 freeze-frame graphics, 258, 375 Family Leave Act, 58 frequency interleaving, 83 far-end camera control, 257,263 explanation of, 96 FASICs, 107 G.728, 120, 298 Fast-Ethernet definition, 106 100Base-FX, 232 G.732, 112 Gaut, Dr. Norm, 13 Franklin D. Roosevelt, 74 geostationary satellite, 431 FCIF, 258 geosynchronous orbit, 432 Federal Communications Commission Gigabit E

thernet Alliance (GEA), 232 establishment of, 74 Global Schoolhouse Project Federal Radio Commission, 72 Index distance learning, 32 H.321, 13, 123 government and public sector enterprises H.322, 13 uses of videoconferencing, 54 introduction of standard, 13 graphical user interface, 5 H.323, 12, 123, 293 graphical user interface (GUI), 5, 434 H.323 gateways, 245 graphics coprocessor, 433 H.324 group systems, 241 ACELP, 128 groups of blocks (GOB), 119 MP-MLQ, 128 groupware, 433 Unrestricted Motion Vectors, 128 Guaranteed Delay, 180 guardband, 433 ITU-T's standard for switched 384 Kbps, Guglielmo Marconi, 66 H.130, 112 HO dialing, 278 HO standard H.221, 120, 121 defined, 120 how DSOs are combined into a single 384 Kbps channel, 207 H.222, 123 H.222.1, 123 dialing, 278 H.223, 127 ITU-T's standard for switched 1.536 H.230, 121 dialing, 121 definition, 121 H.231, 121 dialing, 279 definition, 121 ITU-T's switched 1.920 dialing H.233, 263 specification, 121 H.242 HDTV, 86, 87, 89, 105, 111, 122, 210, 219, 220, 248, 336, 340, 346, 347, 393, 414, definition, 122 432, 436, 439, 444, 452, 461, 487 H.243 Advanced Television Systems Committee control procedures for H.231 MCUs, 120 (ATSC), 219 H.245, 123 data casting over, 219 H.261, 245, 258, 298 Heinrich Hertz, 66 H.263, 99, 103, 126, 127, 128, 129, 176, 177, Hertzian waves, 66 244, 247, 248, 298, 301, 308, 361, 387, HFC, 440 407, 417, 434, 436, 437, 455, 474, 475 high-resolution still images, 307 H.264, 212, 221, 246, 247, 371, 382 history H.320, 12, 120, 142, 245, 258, 293 early history of videoconferencing, 6 enhancing the standard, 249 History of Videoconferencing, 6 its impact on the global videoconferencing market, 245 Hitachi, 245 H.320-to-H.323 gateway, 293 horizontal blanking, 82 Video Communication: the Whole Picture horizontal resolution, 440 International Multimedia Teleconferencing Huffman encoding, 99, 440 Consortium (IMTC), 111, 140 HVAC (heating, venting and air International Standards Organization (ISO), conditioning) 337, 446 problems caused by, 273 Interna

tional Telecommunications Union, icon-driven controls, 263 International Telecommunications Union IETF protocols, 296 (ITU), 111, 335 I-frame International Telecommunications Union's intraframe coding, as defined by MPEG, Telecommunications Standardization Sector (ITU-T), 12 IGMP-2, 184 Internet, 169 image resolution, 306 Internet Activities Board (IAB), 338 impedance, 442 Internet Engineering Task Force, 442 implementing videoconferencing Internet Engineering Task Force (IETF), 169, behavioral changes, 270 Internet Group Management Protocol IMTC, 147 (IGMP), 184 work on T.120 family of Internet Integrated Services, 175 Recommendations, 151 Internet Layer (TCP/IP), 170 I-muxes, 208 Internet Protocol (IP), 124, 169 indirect acoustic coupling, 273 interoperability standards, 11 information security, 131, 312, 313, 314, 315, 316, 319, 471 Interpolation, 445 installation definition, 341 of a group-oriented videoconferencing interviewing clients system, 269 as part of developing a business case, 56 Instructional Television Fixed Service (ITFS), intraframe coding, 243, 445 Intranets, 169, 295 instructions for use of videoconferencing, IP addresses, 171 Intel, 5, 12, 30, 48, 103, 108, 141, 213, 221, classes of, 184 232, 245, 290, 298, 299, 300, 323, 326, 424 IP multicasting, 183 Digital Video Interactive (DVI), 421 what it does, 183 introduction of ProShare, 11 IPSec, 131, 317, 435 Intel's ProShare family of personal IPX, 144, 478 conferencing products, 5 ISDN, 120, 200, 202, 208, 250, 265, 278, 305, Intel's Video System 200, 11 interactive multimedia, 246, 292 B channels, 201 interface, 443 Basic Rate Interface (BRI), 400 interference, 443 Basic Rate Interface Terminal Extender International Electrotechnical Commission (BRITE), 201 (IEC), 337 D channel, 201 Index D-channel, 413 ISO/IEC, 337 HO channels ISO/IEC 11172, 337, 342 and PRI, 207 ISO/IEC 13818, 344 H11, 207 ISO/IEC DIS 10918-1, 337 H12, 207 isochronous service, 224, 305, 446 LAPD, 207, 464 isos, 337 Multilink Point-to-Point Protocol (PPP), ITFS Antenna System,

447 ITT, 93 multirate, 207 Narrowband ISDN, 457 accelerated schedule of standards National ISDN-1 (NI-1) BRI interface approval, 336 as offered on PBXs, 206 ITU-R, 111 NEC 2400's support of NT-1,206 ITU-T, 250, 258 NI-2, 206 ITU-T (Telecommunications Non-Facility Associated Signaling Standardization Sector), 111 (NFAS), 206 ITU-T X.21, 278 Northern Telecom Meridian's support of ITU-TI.451, 207, 464 NT-1, 206 IXC's point-of-presence (POP), 192 James Clark Maxwell, 66 as demarcation point, 202 Joint Technical Committee 1, Sub- NT-1 (network termination, type one), committee 29, 339 Joint Warfare Center Nx64 service, 207 coordinating data transfer, 23 Jones Cable, 32 as an IXC offering, 204 JPEG, 258, 337 Q.921, 207, 464 Keen, Peter G. W., 53 Service Profile Identifier (SPID), 203 Kelvin standards formation, 205 as a measure of light temperature, 275 switched fractional T-1 service, 207 KHz, (definition of), 66 terminal adapter (TA), 203 Kinko's Copy Center videoconferencing products that work videoconferencing public room, 19 over, 403 kWords, 356 ISDN PRI LAN segmentation, 448 NT-2, 204 Lane, Carla, Ed.D, 32 U-interface VS N-interface, 205 LATA, 449 ISDN specifications lavaliere microphone, 274 as first published, 205 layered protocols, 170, 449 ISO Transport Arrives on Top of the TCP/IP (RFC 1006), 147 LDDS WorldCom, 199 Video Communication: the Whole Picture leased line, 449 medical imaging, 35 LEC, 450 MHz, (definition of), 66 LEC access to IXC networks, 196 microphone attenuation, 273 Legal Image Network Communications microphones were attenuated, 273 (LINC), 28 microsegmentation, 227, 453 light angle, 275 Microsoft, 30, 33, 87, 141, 146, 155, 183, 203, light intensity, 275 213, 245, 293, 294, 297, 298, 299, 300, lighting, 275 301, 306, 312, 340, 381, 394, 424, 456 lighting temperatures, 257, 486 Microsoft Office 97, 306 Link Access Protocol-D (LAPD) protocol, Mind Extension University (ME/U), 32 207, 464 minimum illumination levels, 275 lip synch, 307 mission LiveBoard (Xerox Corporation), 48 purpose of orga

nizational mission Local Access and Transport Areas (LATAs), statement, 55 mission and values lossless compression, 97, 451 linking videoconferencing to lossy compression, 98, 451 organizational goals, 55 low-pass filter, 451 Modified Final Judgment, 190 luminance, 451 modulation, 454 monitor placement within a videoconferencing room, 271 as a rating of light sensitivity, 256 mortgage lender LWZ coding, 452 case study, 25 MAC address, 184 MOSPF macroblocks, 119 how it works, 185 making the videoconferencing business case motion compensated prediction business first, 55 as part of B-frame coding, 341 Management Recruiters Inc., 58 motion compensation, 100, 454 Marconi Wireless Telegraph Company, 67 motion vectors, 100, 104, 118 Massachusetts Institute of Technology (MIT), 9 MPEG, 308, 337, 339, 455 MCI, 199 MPEG-1, 455 MCNS, 216, 217 P-frame, 460 MCU, 4, 42, 121, 125, 127, 147, 263, 264, Simple profile 265, 293, 371, 376, 452, 457 definition, 347 MCUs, storage of a database, 376 techniques used to code image sequences, ME/U, 32 MPEG 4 media space, definition, 47 Media Spaces: Bringing People Together in a Video, Audio and Computing 2 Profile, 347 Environment, 47 MPEG-1, 107, 292, 337, 339, 340, 342, 343, Index 344, 345, 346, 347, 348, 358, 359, 394, multiplex, 456 455, 483 Multiplexing how it works, 343 North American digital hierarchy, 94 MPEG-1 parts, 343 Multipoint Computer Application Sharing MPEG-1 syntax, 339 Protocol, 146 MPEG-2, 86, 122, 123, 177, 228, 337, 339, multipoint conferencing etiquette, 280 340, 344, 345, 346, 347, 348, 350, 354, multipoint control unit, 120 356, 357, 358, 359, 434, 436, 455, 482, 483 multipoint control unit (MCU), 4, 121 how it differs from MPEG-1, 347 multipoint personal conferencing, 290 MPEG-2 High Profile, 347 multipoint videoconferences, 4 MPEG-2 levels, 345 Multipurpose Internet Mail Extension MPEG-2 parts, 344, 350 (MIME), 453 MPEG-2 profiles, 346 Mx384, 112 MPEG-2 Simple Profile, 347 named Michael Faraday, 66 MPEG-2 SNR Scalable Profile, 347 narrowcast, 457 MPEG-2 Spatia

lly Scalable Profile, 347 NASA's Jet Propulsion Labs (JPL), 27 MPEG-2 Video Main Profile, 347 National Electric Signaling Company, 67 MPEG-3, 340 National ISDN Council, 206 MPEG-4, 337, 339, 340, 348, 349, 350, 351, National ISDN-1 (NI-1), 206 352, 353, 354, 355, 356, 357, 358, 359, 360, 456, 482 National ISDN-2, 206 MPEG-7, 358, 359, 360 National Science Foundation MTP-2, 147 distance learning over Internet, 32 multicast, 306 National Television Systems Committee multicast backbone (MBONE), 185 establishment of, 76 Multicast Open Shortest Path First needs analysis (MOSPF), 185 as part of the process of developing a Multicast Transport, 147 business case for videoconferencing, 56 Multicast Transport Protocol-2, 147 network access multimedia, 456 tunneling, 189 Multimedia Communications Community network interface, 278 of Interest (MCCOI), 140 Network Interface Layer (TCP/IP), 170 multimedia messaging, 306 network interfaces Multimedia Services and Systems Bell System interfaces, 250 ITU-T Study Group 16, 337 Network Peripherals, 232 multi-mode fiber, 456 Network Specific Mappings (T.131), 148, 149 multipath echo, 273 networks, 457 Multiple Systems Operators (MSOs) carrier's point of presence (POP), 462 as related to cable television network ownership, out-of-band-signaling, 459 Video Communication: the Whole Picture private lines, 463 Panasonic's private networks, 463 case study, 28 Nipkow disc, 457 Pay-Per-View, 461 Nippon Electric Corporation PC-based product first group videoconferencing system, 6 early VTEL system, 11 Nippon Electric Corporation (NEC), 6 PCM, 461 node, 458 pel, 461 noise, 458 persistence of vision, 80, 461 Nokia, 162, 165, 328, 330 personal conferencing, 289 North Slope Borough School definition of, 11 distance learning, 41 product comparison checklist, 305 Northern Telecom, 200, 202, 205 product families, 303 Datapath, 200 personal conferencing product categories, Northridge earthquake surveillance, 29 personal conferencing standards, 296 Novell Network Loadable Modules (NLM), personal confe

rencing systems buyers guide, 303 NT-1s controlling upgrades costs, 304 as they vary in price, 202 performance testing, 305 NTSC, 81, 458 personal conferencing technology Nx384, 458 application of, 303 Nyquist's Theorem, 92 personal conferencing usage model, 289 Nyquist's Theorum, 458 personal conferencing, specifications Oakley, 317,435 development, 141 omnidirectional microphones, 273 Peter Mark Roget, 80 P-frame on-line directories, 307 optical disk drives, 459 predictive coding, for MPEG, 341 ordering digital service phosphor, 462 ESF/B8ZS, 194 photorealism, 259, 375 organizational objectives, 55 phreaker, 311 OSI Reference Model, 170 physical interfaces to the videoconferencing network, 278 out-of-band signaling, 198 picture resolution, 104, 277 packet, 460 Picture-In-Picture, 462 packet switching, 460 Picturephone, 6, 9, 15, 296, 331, 462 packet-switched networks PictureTel, 9, 51, 245 transaction-oriented data, 223 C-2000 codec, 244 PAL, 85, 112 early videoconferencing system, 9 Palm os, 326 founding and early history, 244 Index Hierarchical Vector Quantization (HVQ Protocol-Independent Multicast (PIM), 185 algorithm, 244 PTT, 464 Motion Compensated Transform (MCT) public room, 464 algorithm, 244 Public Switched Telephone Network (PSTN), PictureTel Corporation, 243 public utility commissions (PUCs), 191 how it works, 186 push-to-talk microphones, 274 pixel, 462 Px64, 113, 245 plain old telephone service (POTS), 8, 462 Q.920, 464 point-to-point videoconferences, 4 Q.921, 464 Polycom, 20, 30, 37, 39, 147, 152, 243, 245, Q.931, 464 H channels, 207, 464 Polycom, Inc., 147 QCIF, 464 Post Telephone and Telegraph organizations (PTTs), 336 quadrature modulation, 84 post-Deregulation Act, 194 quantizing, 93, 465 prediction Quarter Common Intermediate Format (QCIF), 114 in motion compensation, 462 QuickTime, 465 Predictive Service (RSVP), 180 radio prioritizing videoconferencing room usage, origins of term, 68 private facilities Radio Act of 1927, 72 renting out excess capacity, 270 Radio Corporation of America (RCA

), 465 Product Announcements, 33 radio frequency interference (RFI), 85 productivity and human resource shortages Radio Manufacturers Association important issues during the early standards, 74 videoconferencing prove-in process, 57 raster, 465 Progressive Networks, 183 raster scan, 465 progressive scanning raster-scan, 81 MPEG-1 use of, 342 real estate Project Management And Consulting virtual staff meeting, 23 case study, 24 Real Time Audio-Visual Control for project vision, 57 Multimedia Conferencing (T.130), 148 projection systems (front or rear), 277 real-time, 466 promoting the use of videoconferencing, 280 real-time compression, 466 proprietary techniques, 463 Real-Time Streaming Protocol (RTSP), 173, ProShare, 11, 12, 141, 245, 299, 300 Real-time Transport Control Protocol, 173, introduction, 12 protocol, 463 Real-time Transport Control Protocol Video Communication: the Whole Picture (RTCP), 297 RFC 2032 (RTP payload format for H.261 Real-time Transport Protocol (RTP), 124, video streams), 298 173, 297 RGB, 257, 277 Reed-Solomon, 87, 217 definition of, 72 Reed-Solomon error correction, 217 RJ-45, 278 Reginald Aubrey Fessenden, Dr., 67 RMP, 147 Regional Bell Operating Companies rollabout group-oriented videoconferencing (RBOCs), 12 systems, 242 Remote access Romano, Pat, 147 definition of, 12 room preparation checklist, 280 Remote Device Control, 150 Rose, Marshall T., 147 Remote Device Control (T.RDC), 148 rotating mode Rendezvous Point (PIM), 186 in an MCU, 264 Republican National Convention router video surveillance, 29 defined, 171 Request For Comments (RFC), 169 routers, 298 Request for Comments (RFCs), 338 RS-170A, 84 Request For Information (RFI) for RS-366 dialing, 200 videoconferencing, 265 RS-366-A dialing, 278 Request for Proposal (RFP) for RSA, 218 videoconferencing, 265 RSVP, 125, 126, 136, 137, 156, 173, 175, 179, Request for Quote (RFQ) for 180, 181, 188, 297, 299, 300, 301, 305, videoconferencing, 265 308, 384, 469 Reservation Systems (T.RES), 147 classes of service, 180 Resource Reservatio

Standards compliance checklist, 308 standards-setting, 111 scientific applications of videoconferencing, stateful firewalls, 175 screen sharing, 305 Steve Harrison, 47 screen sharing products, 291 Store-and-forward switching, 229 SDP, 134, 136, 471, 472 streaming media, 296 security policy, 313, 314 streaming media on Ethernet Senior Management Applications collapsed or distributed backbones, 226 case study, 23 subtractive primaries shared whiteboard, 290 VS additive primaries, 78 ShareView, 11 Sun Microsystems, 232 Video Communication: the Whole Picture Super-VGA (SVGA) formatted signals, 277 T.RES.0, 147 switched 56 T.RES.1, 147 auto-call unit (ACU), 200 T.RES.2, 147 circuit switched digital capability (CSDC), T.RES.3, 147 T.SHARE, 146 cost of, 200 Base Mode, 146 for videoconferencing access, 199 goals, 146 LEC-provided service, 199 Legacy Mode, 146 ping-pong modulation, 200 what it does, 146 time-compression multiplexing (TCM), T-1 carrier, 9 tail length, 255 true transport rates, 200 Tanami Network, 45, 51 two- and four-wire service, 200 Tandberg, 46, 47, 50, 243 switched access TARGA (Truevision Advanced Raster benefits of, 197 Graphics Adapter), 258 switched virtual circuit (SVC), 211 TCP/IP, 147, 169, 170, 172, 173, 175, 184, System Concepts Laboratory (SCL), 47 185, 187, 188, 297, 298, 307, 420, 442, T.120, 12, 141 446, 453, 460, 466, 478, 479 DataBeam, 150 what it does, 170 T.121, 143 TCP/IP (Transmission Control Protocol/Internet Protocol), 169 T.122, 143 Teamwork and collaboration T.123, 144 fostered by videoconferencing, 11 T.124, 144 Telecommunications Standardization Sector T.125, 145 of the ITU, 336 T.126, 145 Telefunken, 85 T.127, 145 telegraph, 66 T.130, 148 telegraph code, 66 specifications included under, 148 telemedicine, 43 what it does, 148 Medical College of Georgia, 43 T.131, 149 microcameras, 44 T.132, 149 television what it does, 149 its ancestral relationship to T.133, 149, 150 videoconferencing, 65 services defined, 150 television system resolutions, 277 T.MT, 147 Texas Instruments T.R

DC, 150 early adopter of videoconferencing, 8 what it does, 150 The World Bank T.RES, 147 virtual seminars, 33 Index third-party development, 306 video file formats, 306 time-based correction, 307 video mail, 484 Toshiba, 243 Video on the Internet touch screen interface, 263 Multicast Backbone, 124 transistors video servers, 292 germanium crystals, 93 video sources, 275 Transmission Control Protocol (TCP), 124, video wall, 485 videoconferencing TransMux, 350, 427, 482 reduction of product-time-to-market, 26 Transport Layer (TCP/IP), 170 videoconferencing, 3 travel expense reduction cost benefit analysis, 57 minimizing the importance of when etiquette, 280 developing the videoconferencing business case, 57 evaluation criteria used in business case, travel savings, 60 indirect benefits stated as part of business T-SHARE case, 57 platformsupport, 146 literal definition, 3 TSS, 375 managing project using, 24 UDP, 147 net gain in operations as part of business unidirectional microphones, 273 case, 57 United Nations operator's console, 262 acceptance of standards, 11 role in managing corporate mergers, 26 User Data Protocol (UDP), 296 seating arrangements, 272 User Datagram Protocol (UDP), 124, 156, system administrator, 285 system administrator's role, 282 User Location Service (ULS), 297 system coordinator, 282 V.35, 278 systems integrator, 269 variable attenuator videoconferencing fact sheet, 280 central clipper, 255 videoconferencing monitors Vector quantization, 103, 483 selection of, 276 Verizon, 21, 159, 160, 330 Video-On-Demand, 485 vertical blanking, 82, 484 videophones, 485 vertical resolution, 484 VideoTelecom Corporation, 244 VGA resolution, 260, 277 VTEL's former name, 9 video, 3 violin defined, 484 lessons over videoconferencing, 22 Video and Electronics Standards Association virtual LAN (VLAN), 229 (VESA), 261 VLSI, 7, 481, 485 video capture board, 484 Video Communication: the Whole Picture voice call-first World Telecommunication Standardization feature of desktop videoconferencing Conference (WTSC 96),

337 systems, 289 World Wide Web (WWW), 5 voice-activated cameras, 274 X.21, 278, 486 voice-activated microphones, 485 inherent dialing features of, 278, 486 voice-activated mode X.21 interface, 278 in an MCU, 264 VSAT, 485 CAP VS DMT, 213 VSI, 243 attenuation, 215 VTEL, 9, 51 XEROX PARC, 47 386-based platform, 244 Y, 487 shipment of first WAN-based Y/C, 487 videoconferencing products, 244 YCbCr, 487 wall colors and coverings, 271 YIQ 84, 487 waveform, 486 YPbPr, 487 white balance, 257, 375, 486 YUV, 487 white noise, 486 zigzag scanning, 487 whiteboard tools, 305 zone manager whiteboarding, 486 defined in T.132, 149 Widcom, 7 zones history of videoconferencing, 7 as they are defined in the T.132 Wilson Learning, 33 Recommendation, 149 wireless transmission, introduction of, 66 zoom lens, 256 WOI-TV, 32 This Page Intentionally Left Blank This Page Intentionally Left Blank Going Wi-Fi Going Make informed decisions about planning Wi-Fi and installing 802.11 "wi-fi" networks. This book helps you tackle the wi-fi challenge, whether installing wi-fi within A Practical Guide to Planning and an existing corporate network or setting Building an 802.11 Network up a wireless network from scratch in any business. Author Janice Reynolds guides Understanding and implementing Wi-Fi in your business workplace or school you through everything you need to know Making it work, whether adding to as existing network or starting from scratch to do it right and to avoid pitfalls in Choosing the right equipment and standards to avoid security, reliability, and changing obsalascance and ensure security and reliability standards. ISBN 1-57820-301-5, $34.95 Janice REYNOLDS Going Mobile Going Mobile Building the Real-Time Enterprise with Mobile Applications that Work This comprehensive guide gives you an Is mobile technology right for your business? objective view of the potential and pitfalls, so How to plan and implement access to critical you can ask the right questions of mobile information when and where it's needed Case studies from r

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he 4G Mobile Network André Perez WILEY First published 2016 in Great Britain and the United States by ISTE Ltd and John Wiley & Sons, Inc. Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms and licenses issued by the CLA. Enquiries concerning reproduction outside these terms should be sent to the publishers at the undermentioned address: ISTE Ltd John Wiley & Sons, Inc. 27-37 St George's Road 111 River Street London SW19 4EU Hoboken, NJ 07030 www.iste.co.uk www.wiley.com © ISTE Ltd 2016 The rights of André Perez to be identified as the author of this work have been asserted by him in accordance with the Copyright, Designs and Patents Act 1988. Library of Congress Control Number: 2016938934 British Library Cataloguing-in-Publication Data A CIP record for this book is available from the British Library ISBN 978-1-84821-923-6 Contents Preface List of Abbreviations Chapter 1. Network Architecture 1.1. EPS network 1.1.1. Functional architecture 1.1.2. Protocol architecture 1.1.3. Bearers 1.2. IMS network 1.2.1. Functional architecture 1.2.2. Protocol architecture 1.3. Databases 1.3.1. Functional architecture 1.3.2. Protocol architecture 1.4. Charging associated with IMS network 1.4.1. Functional architecture 1.4.2. Protocol architecture 1.5. PCC function 1.5.1. Functional architecture 1.5.2. Protocol architecture 1.6. DIAMETER routers 1.7. ENUM system 1.8. IPX network Chapter 2. Signaling Protocols 2.1. NAS protocol 2.1.1. EMM messages VoLTE and ViLTE 2.1.2. ESM messages 2.2. RRC protocol 2.2.1. System information 2.2.2. Control of RRC connection 2.2.3. Measurement report 2.3. S1-AP protocol 2.3.1. Context management 2.3.2. Bearer management 2.3.3. Mobility management 2.3.4. S1-MME interfac

e management 2.4. X2-AP protocol 2.4.1. Mobility management 2.4.2. Load management 2.4.3. X2 interface management 2.5. GTPv2-C protocol 2.5.1. Bearer management 2.5.2. Mobility management 2.6. SIP protocol 2.6.1. Requests 2.6.2. Responses 2.7. SDP protocol 2.8. DIAMETER protocol 2.8.1. Application to EPS network 2.8.2. Application to IMS network 2.8.3. Application to PCC function Chapter 3. Basic Procedures 3.1. Attachment 3.2. Registration 3.3. Deregistration 3.4. Detachment 3.5. Establishment of VoLTE session 3.5.1. Originating side 3.5.2. Terminating side 3.6. Termination of VoLTE session 3.6.1. Initiated side 3.6.2. Received side 3.7. Establishment of ViLTE session 3.8. Termination of ViLTE session 3.9. Emergency call Contents Chapter 4. Radio Interface Procedures 4.1. Radio interface 4.1.1. Data link sub-layer 4.1.2. Logical channels 4.1.3. Transport channels 4.1.4. Physical layer 4.1.5. Physical signals 4.1.6. Physical channels 4.2. Procedures 4.2.1. Access control 4.2.2. Data transfer Chapter 5. Service Profiles 5.1. Subscription data 5.1.1. Subscription to the EPS network 5.1.2. Subscription to the IMS network 5.2. VoLTE profile service 5.2.1. Supplementary telephone services 5.2.2. Audio flow 5.3. ViLTE profile service 5.3.1. Supplementary conversational video service 5.3.2. Video flow Chapter 6. Interconnections 6.1. Interconnection CS network 6.1.1. Functional architecture 6.1.2. Protocol architecture 6.1.3. Session establishment 6.1.4. Session termination 6.2. Interconnection with IMS network 6.2.1. Functional architecture 6.2.2. Session establishment Chapter 7. Handover 7.1. Introduction 7.2. Handover based on X2 7.2.1. Handover based on X2 without relocation 7.2.2. Handover based on X2 with relocation 7.3. Handover based on S1 7.3.1. Handover based on S1 without relocation 7.3.2. Handover based on S1 with relocation VoLTE and ViLTE 7.4. PS-PS inter-system handover 7.4.1. Functional architecture 7.4.2. Procedure Chapter 8. Roaming 8.1. Functional architecture 8.1.1. Roaming applied to the EPS network

8.1.2. Roaming applied to the IMS network 8.2. Procedures 8.2.1. Session establishment for nominal routeing 8.2.2. Session establishment for optimal routeing Chapter 9. Service Centralization and Continuity 9.1. ICS function 9.1.1. Functional architecture 9.1.2. Procedures 9.2. e-SRVCC function 9.2.1. Functional architecture 9.2.2. Procedures Chapter 10. Short Message Service 10.1. Message structure 10.1.1. SM-TL layer 10.1.2. SM-RL layer 10.1.3. SM-CL layer 10.2. SMS over SGsAP 10.2.1. Functional architecture 10.2.2. Procedures 10.3. SMS over SIP 10.3.1. Functional architecture 10.3.2. Procedures Bibliography Index Preface This book presents the mechanisms used in the 4G evolved packet system (EPS) mobile network and in the IP Multimedia sub-system (IMS) for the supply of voice over long term evolution (VoLTE) and video over long term evolution (ViLTE) service (Figure 1). Bearer IP packet IP packet Bearer Operator A Operator B Figure 1. Implementation of VoLTE or ViLTE services The EPS network does not provide telephone service because it does not deal with telephone signaling. VoLTE and ViLTE The EPS network operates in packet-switched (PS) mode and acts as the transport of internet protocol (IP) packets through bearers. The EPS network, therefore, transfers the IP packets containing voice or video real-time transport protocol (RTP) streams or telephone signaling session initiation protocol (SIP). Telephone or videophone service is provided by the IMS network which provides the functions as follows: - routing the call; - supplementary telephone and videophone services; - interconnection to the third-party networks. Chapter 1 presents the architecture of EPS and IMS networks and these networks environment: databases, charging, policy and charging control (PCC), DIAMETER routing, ENUM system and internet protocol exchange (IPX). Chapter 2 presents various signaling protocols: - signaling of the EPS network, allowing the mobile to attach, to update its location, to establish sessions for the transport of IP packe

ts and to change cells during a session (handover); - signaling of the IMS network, allowing the mobile to register, to establish a session and to negotiate the media; - DIAMETER signaling exchanged between, firstly, the EPS or IMS networks, and, secondly, the environment of these networks. Chapter 3 presents the different basic procedures: - the attachment and the detachment of the mobile with the EPS network and the establishment of the default bearer to transport SIP flows; - the registration and the deregistration of the mobile with the IMS network; - the establishment and the release of VoLTE and ViLTE session. Chapter 4 presents the characteristics of the radio interface, for which the following features are described: data structure, transmission chain of the physical layer, frequency time and space multiplexing. Preface The same chapter also illustrates two procedures of the radio interface: access control of the mobile to network and data transfer. Chapter 5 presents the supplementary telephone and videophone services offered by a particular entity of the IMS network, the telephony application server (TAS). These services include call forwarding, identity presentation, message waiting indication, call hold, conference call, call waiting and call barring. It also presents the characteristics of audio and video streams. Chapter 6 presents the interconnection to the public switched telephone network (PSTN) or to the public land mobile network (PLMN) (Figure 2). IP packet IP packet Figure 2. Interconnection to the PSTN and PLMN network Chapter 6 also presents the interconnection of the IMS network with IMS third-party networks. Chapter 7 presents the mechanisms of intra-system and PS-PS inter- system handover. The intra-system handover is performed when the mobile changes cell but does not change the 4G network concerned. The PS-PS inter-system handover is performed when the mobile changes cell and network but holds the PS mode. This type of handover is applied to VoLTE or ViLTE services if the same function

ality exists in the HSPA evolution of 3G network. VoLTE and ViLTE Both handover modes are transparent to VoLTE and ViLTE services, the movement of the mobile being masked for the IMS network. Chapter 8 presents the roaming for which two routing methods of the RTP streams are described: - nominal routeing of the RTP stream that passes through the home network; - optimal routeing of the RTP stream that does not pass through the home network. Chapter 9 presents the centralization of services implemented by IMS centralized services (ICS) that enables the IMS network to offer VoLTE and ViLTE services regardless of the network where the mobile phone is connected. Chapter 9 also presents the continuity of services implemented by function enhanced single radio voice call continuity (e-SRVCC) which ensures that the communication is maintained in case of PS-CS (Circuit- Switched) inter-system handover (Figure 3). IP packet 2G / 3G Network IP packet CS mode Figure 3. PS-CS inter-system handover Preface Chapter 10 presents the two modes providing short message service (SMS). Short message service over SGsAP allows a mobile connected to the 4G network to send and receive SMS in the CS mode. Short message service over SIP is a supplementary telephone service provided by the IMS network. André PEREZ April 2016 List of Abbreviations Authorization-Authentication-Answer Authorization-Authentication-Request Accounting-Answer Address Complete Message Accounting-Request Application Function Authentication-Information-Answer Authentication-Information-Request Acknowledged Mode Aggregate Maximum Bit Rate Adaptive Multi-Rate AMR WB AMR Wide Band Answer Message Advice of Charge Application transport Mechanism Access Point Name Allocation and Retention Priority Automatic Repeat Request VoLTE and ViLTE Application Server Abort-Session-Answer Abort-Session-Request Access Transfer Control Function Access Transfer Gateway ATU-STI Access Transfer Update - Session Transfer Identifier Authentication Network B2BUA Back-to-Back User Agent Broadcas

t Control Channel Broadcast Channel Bearer Control Tunnelling Protocol Breakout Gateway Control Function Bearer Independent Call Control Buffer Status Report Base Station Sub-system Carrier Aggregation Camel Application Part Customized Alerting Tone Constrained Baseline Profile Component Carrier Credit-Control-Answer Completion of Communications to Busy Subscriber Common Control Channel Completion of Communications on Not Logged-in List of Abbreviations Completion of Communications on No Reply Credit-Control-Request Communication Deflection Charging Data Function Communication Diversion Charging Data Record Communication Forwarding on Busy User Control Format Indicator Communication Forwarding on Not Logged-in Communication Forwarding on no Reply Communication Forwarding Unconditional Charging Gateway Function Cipher Key Cancel-Location-Answer Cancel-Location-Request Call Management Commercial Mobile Alert System Comfort Noise Generation Cyclic Prefix Channel Quality Indicator Contention Resolution Identity C-RNTI Cell RNTI Customised Ringing Signal Circuit-Switched Call Session Control Function CS FallBack Charging Trigger Function Closed User Group Communication Waiting xviii VoLTE and ViLTE Dedicated Control Channel Downlink Control Information Delete-Subscriber-Data-Answer Delete-Subscriber-Data-Request DIAMETER Edge Agent DL-SCH Downlink Shared Channel Domain Name System Data Radio Bearer DM-RS Demodulation Reference Signal DIAMETER Routing Agent Discontinuous Reception DiffServ Code Point Dedicated Traffic Channel Discontinuous Transmission DwPTS Downlink Pilot Time Slot Emergency Access Transfer Function E-UTRAN Cell Global Identifier E-CSCF Emergency-CSCF Explicit Communication Transfer End Marker EPS Mobility Management evolved Node B Evolved Packet Core Evolved Packet System E-RAB EPS Radio Access Bearer List of Abbreviations EPS Session Management e-SRVCC enhanced Single Radio Voice Call Continuity Earthquake and Tsunami Warning System E-UTRAN Evolved Universal Terrestrial Radio Access Network Enhanced

Voice Services Flexible Alerting Full Band Frequency Division Duplex Fast Fourier Transform Full Rate Guaranteed Bit Rate Gateway GPRS Support Node Gateway MSC Gap Period General Packet Radio Service Global System for Mobile GTP-C GPRS Tunnel Protocol Control GTP-U GPRS Tunnel Protocol User Globally Unique Temporary Identity Hybrid ARQ HARQ Indicator High Interference Indication Home Location Register VoLTE and ViLTE H-PCRF Home PCRF Half Rate Home Subscriber Server Hypertext Transfer Protocol Initial Address Message Interconnection Border Control Function Incoming Communication Barring IMS Centralized Services Inter-Cell Interference Coordination I-CSCF Interrogating-CSCF Insert-Subscriber-Data-Answer Insert-Subscriber-Data-Request Internet Engineering Task Force initial Filter Criteria Inverse Fast Fourier Transform Integrity Key IMS Private User Identity IMS Public User Identity IP Multimedia Routing Number IP Multimedia Sub-system IMS-GWF IMS Gateway Function International Mobile Subscriber Identity Interference Overload Indication Internet Protocol IPBCP IP Bearer Control Protocol IPSec IP Security IP-SM-GW IP Short Message Gateway List of Abbreviations Internet Protocol eXchange IMS Service Control IMS Services Identity Module ISDN User Part IWMSC Inter Working MSC Location Area Identifier Logical Channel Identifier Location-Info-Answer Location-Info-Request Location Retrieval Function Long Term Evolution Multimedia-Auth-Answer Media Access Control Multimedia-Auth-Request Maximum Bit Rate MBSFN RS MBMS Single Frequency Network RS Mobile Country Code Multicast Control Channel Multicast Channel Malicious Communication Identification Media Gateway Control Function Multimedia Gateway Master Information Block Multiple Input Multiple Output Multiple Input Single Output VoLTE and ViLTE Mobility Management Entity Mobile Network Code Main Profile Multimedia Resource Function MRF Controller MRF Processor Mobile-services Switching Centre MDISDN Mobile Subscriber ISDN Number Multicast Traffic Channel Message Waiting I

ndication Network Address and Port Translation NAPT-PT NAPT Protocol Translation Non Access Stratum Narrow Band Notify-Answer Notify-Request Outgoing Communication Barring Online Charging System Offline Charging System Orthogonal Frequency-Division Multiplexing OFDMA Orthogonal Frequency-Division Multiple Access Originating Identification Presentation Originating Identification Restriction Optimal Media Routeing OTDOA Observed Time Difference of Arrival List of Abbreviations xxiii Physical Broadcast Channel Policy and Charging Control Paging Control Channel Policy and Charging Enforcement Function PCFICH Physical Control Format Indicator Channel Paging Channel Physical-layer Cell Identity Policy Charging and Rules Function P-CSCF Proxy-CSCF PDCCH Physical Downlink Control Channel Packet Data Convergence Protocol Packet Data Network PDSCH Physical Downlink Shared Channel PDN Gateway PHICH Physical HARQ Indicator Channel Power Headroom Report Public Land Mobile Network Physical Multicast Channel Precoding Matrix Indicator Push-Notification-Answer Push-Notification-Request Push-Profile-Answer Push-Profile-Request PRACH Physical Random Access Channel Positioning Reference Signal Packet-Switched Public Safety Answering Point Public Service Identity VoLTE and ViLTE Primary Synchronization Signal Public Switched Telephone Network PUCCH Physical Uplink Control Channel Profile-Update-Answer Profile-Update-Request PUSCH Physical Uplink Shared Channel Quadrature Amplitude Modulation QoS Class Identifier Quality of Service Quadrature Phase-Shift Keying Re-Auth-Answer Random Access Channel Random Access Response Re-Auth-Request RA-RNTI Random Access RNTI Radio Access Technology Resource Block Resource Element Release Request For Comments Rank Indicator Radio Link Control Release Complete Radio Network Controller Radio Network Temporary Identity List of Abbreviations Relative Narrowband Tx Power Robust Header Compression Radio Resource Control Reference Signal Reset-Answer Reset-Request Reference Signal Received Power Referenc

e Signal Received Quality Registration-Termination-Answer Real-time Transport Protocol Registration-Termination-Request Redundancy Version Server-Assignment-Answer Server-Assignment-Request SCC AS Service Centralization and Continuity AS SC-FDMA Single Carrier Frequency Division Multiple Access S-CSCF Serving-CSCF Service Data Flow Session Description Protocol Service GPRS Support Node System Frame Number Serving Gateway System Information Block SIGTRAN Signalling Transport over IP Single Input Multiple Output Session Initiation Protocol SIP-I SIP with Encapsulated ISUP VoLTE and ViLTE SI-RNTI System Information RNTI Single Input Single Output Subscription Locator Functional SM-AL Short Message Application Layer SM-CL Short Message Control Layer SM-RL Short Message Relay Layer SM-TL Short Message Transport Layer Short Message Service SMS-SC SMS Service Center Subscribe-Notifications-Answer Subscribe-Notifications-Request Subscription Profile Repository Semi-Persistent Scheduling Signalling Radio Bearer Sounding Reference Signal Signalling System 7 Secondary Synchronization Signal Session-Termination-Answer S-TMSI Shortened-TMSI STN-SR Session Transfer Number for SRVCC Session-Termination-Request Super Wide Band Timing Advance Tracking Area Identity Telephony Application Server TC-RNTI Temporary Cell RNTI Time Division Duplex List of Abbreviations xxvii Time Division Multiplexing Tunnel Endpoint Identifier Topology Hiding Interconnect Gateway Terminating Identification Presentation Terminating Identification Restriction Transparent Mode Temporary Mobile Subscriber Identity Transmit Power Control Transit and Roaming Function Transition Gateway Transmission Time Interval User Agent User-Authorization-Answer User Agent Client User-Authorization-Request User Agent Server Uplink Control Information User-Data-Answer User-Data-Request User Equipment Universal Integrated Circuit Card Update-Location-Answer Update-Location-Request UL-SCH Uplink Shared Channel Unacknowledged Mode Universal Mobile Telecommunications System U

V-PCRF Visited PCRF Wide Band XML Configuration Access Protocol eXtensible Markup Language Network Architecture 1.1. EPS network 1.1.1. Functional architecture The functional architecture of the evolved packet system (EPS) network is illustrated in Figure 1.1. E-UTRAN Figure 1.1. Functional architecture of EPS network VoLTE and ViLTE: Voice and Conversational Video Services over the 4G Mobile Network, First Edition. André Perez. ISTE Ltd 2016. Published by ISTE Ltd and John Wiley & Sons, Inc. VoLTE and ViLTE The EPS mobile network consists of an evolved packet core (EPC) network and an evolved universal terrestrial radio access network (E-UTRAN). The E-UTRAN access network ensures the connection of the User Equipment (UE). The EPC core network interconnects the access networks, provides the interface to the packet data network (PDN) and ensures the attachment of mobile phones and the establishment of bearers. 1.1.1.1. eNB entity The E-UTRAN access network includes a single type of entity, the evolved Node Base station (eNB) that connects to the mobiles. The eNB entity is responsible for the management of radio resources, for the control of the establishment of the data radio dearer (DRB), in which the mobile traffic is transmitted and for its mobility management during the session (handover). The eNB entity transfers the traffic data from the mobile (respectively from the Serving Gateway (SGW)) to the SGW entity (to the mobile phones concerned, accordingly). When the eNB entity receives data from the mobile or the SGW entity, it refers to the QoS class identifier (QCI) in accordance with the data scheduling mechanism. The eNB entity can perform the marking of the DiffServ code point (DSCP) field of IP header, based on the assigned QCI identifier, for the outgoing data to the SGW entity. The eNB entity performs compression and encryption of traffic data on the radio interface. The eNB entity performs encryption and integrity control of signaling data exchanged with the mobile. It also undertakes the selection of t

he mobility management entity (MME) to which the mobile is attached. Network Architecture It treats paging requests sent by the MME entity for their distribution in the cellphone corresponding to the radio coverage area of the eNB entity. The eNB entity also distributes system information to the cell containing the technical characteristics of the radio interface and allowing the mobile access to connect. The eNB entity uses the measurements made by the mobile to decide on the initiation of a cell change during a session (handover). 1.1.1.2. MME entity The MME entity is the network control tower, allowing mobile access and controlling bearer establishment for the transmission of traffic data. The MME entities belong to a group (pool). Load balancing of MME entities is provided by the eNB entities within a group that must have access to each MME entity of the same group. The MME entity is responsible for attachment and detachment of the mobile phone to the network concerned. During attachment, the MME entity retrieves the subscriber's profile and the subscriber's authentication data stored in the home subscriber server (HSS) and performs authentication of the mobile. During attachment, the MME entity registers the tracking area identity (TAI) of the mobile and allocates a globally unique temporary identity (GUTI) to the mobile which replaces the private international mobile subscriber identity (IMSI). The MME entity manages a list of location areas allocated to the mobile, where the mobile can move in an idle state, without contacting the MME entity to update its TAI location area. When attaching the mobile, the MME selects SGW and PGW (PDN Gateway) entities for the construction of the default bearer, e.g. for the transport of IP packets containing Session Initiation Protocol (SIP) signaling. VoLTE and ViLTE For the construction of the bearer, the selection of the PGW entity is obtained from the access point name (APN), communicated by the mobile or by the HSS entity in the subscriber's profile. The source MME ent

ity also selects the target MME entity when the mobile changes both cell and group (pool). The MME entity provides the information required for lawful interception, such as the mobile status (idle or connected), the TAI location area if the mobile is idle or the E-UTRAN Cell Global Identifier (ECGI) if the mobile is in session. 1.1.1.3. SGW entity The SGW entities are organized into groups (pools). To ensure load balancing of SGW entities, each eNB entity within a group must have access to each SGW entity of the same group. The SGW entity forwards incoming data from the PGW entity to the eNB entity and outgoing data from the eNB entity to the PGW entity. When the SGW entity receives data from the eNB or PGW entities, it refers to the QCI identifier for the implementation of the data scheduling mechanism. The SGW entity can perform marking of the DSCP field of IP header based on the assigned QCI identifier for incoming and outgoing data. The SGW entity is the anchor point for intra-system handover (mobility within EPS network) provided that the mobile does not change group. Otherwise, the PGW entity performs this function. The SGW entity is also the anchor point at the inter-system handover PS-PS, requiring the transfer of traffic data from the mobile to the second or third generation mobile network. The SGW entity informs the MME entity of incoming data when the mobile is in idle state, which allows the MME entity to trigger paging of all eNB entities of the TAI location area. Network Architecture A mobile in the idle state remains attached to the MME entity. However, it is no longer connected to the eNB entity and thus the radio bearer and the S1 bearer are deactivated. 1.1.1.4. PGW entity The PGW entity is the gateway router providing the EPS network connection to the PDN network. When the PGW entity receives data from the SGW entity or PDN network, it refers to the QCI identifier for the implementation of the data scheduling mechanism. The PGW entity can perform DSCP marking of IP header based on the assigned

QCI identifier. During attachment, the PGW entity grants an IPv4 or IPv6 address to the mobile. The PGW entity constitutes the anchor point for inter-SGW mobility when the mobile changes groups. The PGW entity hosts the policy and charging enforcement function (PCEF) which applies the rules relating to mobile traffic data on packet filtering, on charging and on quality of service (QoS) to be applied to the bearer to build. The policy charging and rules function (PCRF) entity, outside the EPS network, provides the PCEF function of the PGW entity with the rules to apply when establishing bearers. The PGW entity generates data for use by charging entities to develop the record tickets processed through the billing system. The PGW entity performs replication of the mobile traffic data within the framework of lawful interception. 1.1.2. Protocol architecture The protocol architecture of the EPS network is illustrated in Figure 1.2 for the control plane and in Figure 1.3 for the traffic plane. VoLTE and ViLTE S1-MME S1-AP S1-AP GTP-C GTP-C GTP-C GTP-C LTE L1 LTE-L1 eNode B Figure 1.2. Protocol architecture: control plane The LTE-Uu interface is the reference point between the mobile and the eNB entity. This interface supports radio resource control (RRC) signaling exchanged between the mobile and the eNB entity, transmitted in the signaling radio bearer (SRB) and the mobile traffic data transmitted in the data radio bearer (DRB). The RRC signaling also provides transport of the non-access stratum (NAS) protocol exchanged between the mobile and the MME entity. GTP-U GTP-U GTP-U GTP-U Bearer Bearer LTE-L1 LTE-L1 eNode B Figure 1.3. Protocol architecture: traffic plane The S1-MME interface is the reference point between the MME and eNB entities for signaling, via the S1-AP (Application Part) protocol. Network Architecture The S1-AP protocol also provides transport of the NAS protocol exchanged between the mobile and the MME entity. The S11 interface is the reference point between the MME and SGW entities for signaling via

the GPRS (General Packet Radio Service) tunnel control protocol (GTPv2-C). The S5 interface is the reference point between the SGW and PGW entities for signaling via the GTPv2-C protocol and traffic data (IP packets) via the GPRS tunnel protocol user (GTP-U). The S10 interface is the reference point between the MME entities for signaling, via the GTPv2-C protocol. The S1-U interface is the reference point between the eNB and SGW entities for traffic data, via the GTP-U protocol. The SGi interface is the reference point between the PDW entity and the PDN network (Internet). The X2 interface is the reference point between two eNB entities for signaling, via the X2-AP protocol (Figure 1.4) and for incoming traffic data via the GTP-U protocol when mobile changes cells (Figure 1.5). X2-AP X2-AP eNB cible eNB source Figure 1.4. Protocol architecture of the X2 interface: control plane The bearer established between the two eNB entities is unidirectional (eNB source to eNB target). It allows for the transfer of traffic data received VoLTE and ViLTE from the SGW entity to the target eNB entity. It is established temporarily, for the time of the handover of the mobile. GTP-U GTP-U GTP-U GTP-U GTP-U Bearer Bearer Bearer LTE-L1 LTE L1 eNB cible eNB source Figure 1.5. Protocol architecture traffic plane during handover based on the X2 interface 1.1.3. Bearers 1.1.3.1. Bearer structure The EPS network carries traffic data (IP packets) transparently to the PGW entity that performs packet routing. The IP packet is carried in bearers constructed between EPS network entities (Figure 1.6). EPS Bearer Radio Access Bearer Radio Bearer S1 Bearer S5 Bearer GTP-C Figure 1.6. Construction of the bearers Network Architecture The data radio bearer (DRB) is constructed between the user equipment (UE) and the eNB entity. The RRC signaling, which is exchanged between the mobile and the eNB entity, is responsible for constructing this bearer. The S1 bearer is constructed between the eNB and SGW entities. The S1-AP signaling, exchanged between

the eNB and MME entities and the GTPv2-C signaling, exchanged between the MME and SGW entities, are responsible for constructing this bearer. The S5 bearer is constructed between the SGW and PGW entities. The GTPv2-C signaling exchanged between the SGW and PGW entities is responsible for constructing this bearer. The connection of the radio bearer and the S1 bearer, performed by the eNB entity, constitutes the EPS radio access bearer (E-RAB). The connection of the E-RAB and S5 bearers, which is performed by the SGW entity, constitutes the EPS bearer. The PGW entity is the only EPS mobile network entity that routes traffic data (IP packets). The IP transport network that enables communication between the EPS network entities routes the S1 or S5 bearers. The eNB and SGW entities do not perform routeing. They only provide the connection between the bearers. There are two types of bearers in the EPS network: - the default bearer established when attaching the mobile, used for example to transport SIP signaling; - the dedicated bearer, established following a specific request from the mobile, used for example for transport of real time protocol (RTP) streams containing voice or video. 1.1.3.2. Quality of Service The EPS bearer can be of guaranteed bit rate (GBR) type or can be of non-GBR type. VoLTE and ViLTE Table 1.1 provides the QoS characteristics associated with these two bearer families. QoS characteristics Non-GBR QCI (QoS Class Identifier) ARP (Allocation and Retention Priority) GBR (Guaranteed Bit Rate) MBR (Maximum Bit Rate) APN-AMBR (Aggregate Maximum Bit Rate) UE-AMBR Table 1.1. QOS characteristics The QCI parameter indicates the priority level, the delay and the packet loss rate (Table 1.2). QCI from 1 to 4 are assigned to GBR bearers. QCI from 5 to 9 are assigned to non-GBR bearers. Resource Packet loss Priority Delay Examples of services 100 ms Voice 150 ms Video Calling 50 ms Games 300 ms Video. 100 ms SIP Signaling 300 ms Video, Internet 100 ms Voice, Video, Non-GBR Games 300 ms Video, Internet Table

1.2. QCI parameters Network Architecture The scheduling of traffic data carried out at the level of the eNB, SGW and PGW entities is based on the QCI priority level. The bit rate control is done from the GBR and MBR parameters for guaranteed bit rate bearers. The bit rate control is conducted for each bearer at the eNB and PGW entities for incoming data in the EPS network. The bit rate control is done from the APN-AMBR and UE-AMBR parameters for non-GBR type bearers. This control is performed for aggregated bit rates of non-GBR bearers of a mobile. The APN-AMBR parameter controlled by the PGW entity corresponds to the maximum bit rate authorized for all the streams of a mobile phone using non-GBR bearers at the PGW entity level. The UE-AMBR parameter controlled by the eNB entity corresponds to the maximum authorized bit rate for all streams of a mobile phone using non-GBR bearers, at the eNB entity level. The pre-emption implemented at the eNB and PGW entity level corresponds to the ARP parameter that defines the following information: - pre-emption capability: this parameter is used for the establishment of a new session, if the resource is not available. This parameter determines whether or not a new session can pre-empt an existing session; - pre-emption vulnerability: this parameter is used by the existing session. This parameter is compared to the pre-emption capability parameter of the new session to determine whether the existing session can be pre- empted or not; - priority: this determines the priority level associated with pre-emption. This priority level is independent of that set for the QCI parameter. The QoS parameters (QCI, ARP and APN-AMBR) relating to default bearers are stored in the HSS entity. These values can be changed by the PCRF entity. The QoS parameters (QCI, ARP, GBR and MBR) relating to dedicated bearers are stored in the subscription profile repository (SPR) entity associated with the PCRF entity. VoLTE and ViLTE The MME entity replaces the UE-AMBR parameter provided by the HSS entit

y by the sum of the different APN-AMBR parameters, provided it is less than the value indicated by the HSS entity. 1.2. IMS network 1.2.1. Functional architecture The functional architecture of the IP multimedia subsystem (IMS) network is described in Figure 1.7. The IMS network includes the following entities: - call session control function (CSCF), involving P-CSCF (Proxy-CSCF), S-CSCF (Serving-CSCF), I-CSCF (Interrogating-CSCF) and E-CSCF (Emergency-CSCF); - application servers (AS), involving telephony application server (TAS); - multimedia resource function (MRF), involving MRFC (MRF Controller) and MFRP (MRF Processor). Traffic stream Control stream P-CSCF E-CSCF Interconnection I-CSCF S-CSCF with CS network with IMS network Figure 1.7. Functional architecture of IMS network Network Architecture 1.2.1.1. P-CSCF entity The P-CSCF entity is the first point of contact for the mobile in the IMS network. It performs the function of a PROXY SERVER. It receives the requests from the UE or from the S-CSCF entity and transfers them respectively to the S/I-CSCF entity or to the UE entity. The P-CSCF entity may also act as an user agent (UA) in abnormal operating conditions, when it has to terminate or generate SIP transactions. During registration, the P-CSCF entity forwards the SIP REGISTER request to the I-CSCF entity determined on the basis of the domain name provided by the UE entity. Into this message, it adds a header path containing its identity. This identity is preserved by the S-CSCF entity. During session establishment, the P-CSCF entity forwards the SIP INVITE request received from the S-CSCF entity (or from the UE entity respectively) to the UE entity (or respectively to the S-CSCF entity). To carry out the transfer, the P-CSCF entity has to retrieve the IP addresses of the UE entity (or respectively of the S-CSCF entity): - the SIP INVITE request received from the S-CSCF entity contains the IP address of the UE entity instead of the uniform resource identifier (URI); - the SIP INVITE request received fr

om the UE entity contains the identity of the S-CSCF entity in the header route. The P-CSCF entity detects emergency calls and forwards them to the E-CSCF entity. The P-CSCF entity generates the data necessary for the generation of charging tickets. The P-CSCF entity establishes an IPSec (IP Security) association with the UE at its registration. During session establishment, the P-CSCF entity controls the type of resources required by the UE on the basis of the capacities authorized by the EPS network, using the DIAMETER messages exchanged with the PCRF entity. VoLTE and ViLTE During session establishment, the P-CSCF entity checks resource availability in the EPS network. 1.2.1.2. I-CSCF entity The I-CSCF entity is the specific point of contact within the IMS network for some transactions coming from the P-CSCF or S-CSCF entities. It performs the function of a PROXY SERVER. Upon receipt of the first SIP REGISTER request, the I-CSCF assigns an S-CSCF entity to the UE entity and transfers the request to the S-CSCF entity chosen. To fulfill this function, an exchange of DIAMETER messages with the HSS entity is necessary. Upon receipt of the second SIP REGISTER request and the first SIP INVITE request, for an incoming call, the I-CSCF entity queries the HSS entity for the IP address of the S-CSCF entity attributed to the UE entity and transfers the request to that S-CSCF entity. The I-CSCF entity forwards the data necessary for the generation of charging tickets. 1.2.1.3. S-CSCF entity The S-CSCF entity provides the UE entity with session control services. It performs different roles depending on the type of request received: - that of a REGISTRAR for the registration of the UE entity; - that of a LOCATION SERVER for the storage of the correspondence between the IP address and the URI identity of the UE entity; - that of a PROXY SERVER for the establishment of a session; - that of an UA, in abnormal operating conditions, when it has to terminate or generate SIP transactions. On receiving the first REGISTER request, t

he S-CSCF entity contacts the HSS entity to recover the UE authentication data. To fulfill this function, an exchange of DIAMETER messages with the HSS entity is required. The S-CSCF entity responds with a message 401 unauthorized containing the parameters used for authentication. On receiving the second REGISTER request, The S-CSCF entity authenticates the UE and recovers its profile from the HSS entity. It responds Network Architecture with a message 200 OK containing a header Service Route with its IP address which the UA keeps in its memory. For an outgoing call, on receipt of the first INVITE request from the P-CSCF entity, the S-CSCF entity performs a check on the service required on the basis of the profile recovered during registration. The S-CSCF entity transfers the request either to the application server or to the entity allocated to the interconnection. The IP address of the application server is contained in the profile of the UE entity recovered during registration. For an incoming call, on receipt of the first INVITE request from the I-CSCF entity, the S-CSCF entity performs a check on the service required. The S-CSCF entity transfers the request either to the application server or to the P-CSCF entity.I S-CSCF, as suggested in the latter case, the entity replaces the URI identity of the request with the IP address of the UE entity. The IP address of the P-CSCF entity is recovered on the basis of the header Path, during the registration of the UE entity. The S-CSCF entity forwards the data necessary to generate charging tickets. 1.2.1.4. E-CSCF entity The E-CSCF entity handles emergency calls transmitted by the P-CSCF and routes the request to the public-safety answering point (PSAP) nearest to the UE. The PSAP emergency center can be linked to a fixed or mobile network or to another IMS network. Upon receiving the INVITE request, the E-CSCF entity retrieves the location of the mobile in the header P-Access-Network-Info. The header P-Access-Network-Info was inserted by the P-CSCF entity. The value

of the mobile location was provided by the PGW entity through the PCRF entity. On receiving the INVITE request, the E-CSCF entity contacts the location retrieval function (LRF) to obtain the URI identity of the PSAP emergency center. On the basis of information provided by the LRF entity, the E-CSCF entity transfers the request to the entity allocated to the interconnection to the CS network or the IMS network. VoLTE and ViLTE 1.2.1.5. Application servers The application server provides added-value services to the IMS network. For instance, it hosts and executes the supplementary telephone services. The AS entity may affect the SIP session depending on the service required. The S-CSCF entity has to decide whether an application server is necessary for a specific treatment of an SIP request to ensure handling of the appropriate service. The decision is based on the information received from the HSS during mobile registration. The application server may play various roles in the processing of an SIP message: - that of a PROXY SERVER. In this mode, the SIP request from the S-CSCF entity is sent to the application server. The application server can add, remove or modify headers in the SIP message; - that of an User Agent Server (UAS) or a REDIRECT SERVER. In this mode, the response of the application server to the SIP request from the S-CSCF entity is 2xx, 4xx, 5xx or 6xx (UAS) or 3xx (REDIRECT SERVER); - that of an user agent client (UAC). In this mode, the application server generates the SIP request and transmits it to the S-CSCF entity. - that of a Back to Back User Agent (B2BUA). In this mode, the application server receiving an SIP request from the S-CSCF entity terminates the dialog with the UAC entity at the originating side, and generates a new request with an UAS entity at the terminating side. 1.2.1.6. Media processing Media processing is done by the MRF function, divided into two entities, the MRFC and MRFP. The MRFC entity interprets information from the S-CSCF and controls the MRFP on the basis of this

interpretation; The MRFC entity forwards the data necessary for the generation of charging tickets. Network Architecture The MFRP entity generates media flows under the control of the MRFC, such as telephone announcements. The MFRP entity combines media flows to provide a conferencing service. The MFRP entity can also perform particular treatments of the media flows, such as the transcoding of the audio signal. 1.2.2. Protocol architecture The Gm interface is the reference point between the EU and P-CSCF entities. This interface supports SIP and Session Description Protocol (SDP) signaling. The Ut interface is the reference point between the EU and TAS entities. This interface supports XML Configuration Access Protocol (XCAP) signaling, allowing the configuration of supplementary services by the mobile. The Mw interface is the reference point between the CSCF entities. This interface supports SIP and SDP signaling. The Mx interface is the reference point between, on the one hand, the CSCF entities and, the other hand, the interconnection with the Circuit- Switched (CS) network or the IMS network. This interface supports SIP and SDP signaling. The Mr interface is the reference point between the S-CSCF and MRFC entities. This interface supports SIP and SDP signaling. The Mb interface is the reference point between the UE and MRFP entities. This interface supports the RTP stream. The IMS service control (ISC) interface is the reference point between the S-CSCF and TAS entities. This interface supports SIP and SDP signaling. VoLTE and ViLTE 1.3. Databases 1.3.1. Functional architecture The HSS entity is a database storing the data specific to each user. The main data stored include the identities of the users, the authentication parameters and the service profile. The subscriber has a private identity IMSI used when attaching to the EPS network. The subscriber has an IMS private identity (IMPI) used while registering to the IMS network, and an IMS public identity (IMPU) when establishing a voice or a conversational

video call. The authentication parameters are used to control access to the mobile for attachment to the EPS network or registration to the IMS network. The service profile determines the services that mobile has subscribed. The S-CSCF entity accesses the HSS entity to recover the authentication data and the service profile. The I-CSCF entity accesses the HSS entity to retrieve the identity of the S-CSCF entity that has attached the mobile. The TAS entity can access the HSS entity to retrieve service data necessary for the performance of the supplementary telephone service. The subscription locator function (SLF) is a database that records the identity of the HSS entity where the mobile subscription was recorded, in the case where several HSS entities are deployed. 1.3.2. Protocol architecture The S6a interface is the reference point between the MME and HSS entities. This interface supports the DIAMETER signaling. The Cx interface is the reference point between, on the one hand, the I-CSCF or S-CSCF entities, while the HSS entity on the other. This interface supports the DIAMETER signaling. Network Architecture The Sh interface is the reference point between the TAS and HSS entities. This interface supports the DIAMETER signaling. The Dx interface is the reference point between, on the one hand, the I-CSCF or S-CSCF entities and the other hand, the SLF entity. This interface supports the DIAMETER signaling. The Dh interface is the reference point between the SLF and TAS entities. This interface supports the DIAMETER signaling. 1.4. Charging associated with IMS network 1.4.1. Functional architecture In the case of online charging, the user's account is consulted before granting the permission to use the network resource. That account is decreased during the communication. When it reaches zero, the communication is cut off. This mode of charging corresponds to pre-paid service. 1.4.1.1. Offline charging The functional architecture of the offline charging system (OFCS) is described in Figure 1.8. The charging trigge

r function (CTF) generates charging events based on the observation of the use of network resources. It is integrated in all the entities of the IMS network. The charging data function (CDF) receives the charging data from the CTF function. The CDF function then uses these data to generate charging data records (CDR). The charging data records produced by the CDF function are kept in the charging gateway function (CGF), a database which acts as a gateway with the billing system. 1.4.1.2. Online charging The functional architecture of the online charging system (OCS) is described in Figure 1.9. 20 VoLTE and ViLTE DIAMETER Billing system S-CSCF I-CSCF P-CSCF Figure 1.8. Functional architecture of OFCS DIAMETER Billing System S-CSCF IMS-GWF Figure 1.9. Functional architecture of OCS The S-CSCF entity does not trigger any charging event and does not necessarily include the CTF function. Charging during a session is a service logic controlled by an application server IMS Gateway Function (IMS-GWF). The OCS entity comprises several distinct modules: - charging on the basis of the sessions established by the users (e.g. voice calls); - charging on the basis of events in conjunction with application servers; Network Architecture - valorization of the use of network resources to calculate the amount of charging; - balance of the user's account. The generation of CDRs sent to the billing system is optional. If the OCS entity does not produce CDRs, they are used by the same CDF as with offline charging. 1.4.2. Protocol architecture The Rf interface is the reference point between, on the one hand, the entities of the IMS network, while on the other hand, the OFCS entity. This interface supports the DIAMETER signaling. The Ro interface is the reference point between, on the one hand, the entities of the IMS network, and on the other hand, the OCS entity. This interface supports the DIAMETER signaling. 1.5. PCC function 1.5.1. Functional architecture The functional architecture of the policy and charging control (PCC) is descr

ibed in Figure 1.10. The PCRF entity provides to the PCEF entity, integrated in the PGW entity, the necessary information for the control and the charging of the traffic data (IP packets). This information is stored in the subscription profile repository (SPR) during the creation of the subscription. Traffic control includes the following: - association between a service data flow (SDF) and EPS bearer; - blocking or allowing IP packets; - allocation of QCI parameter to EPS bearer. VoLTE and ViLTE IMS (P-CSCF) Figure 1.10. Functional architecture of PCC The charging method defines as if the PCEF entity has to obtain credit from the OCS entity for online charging or if it has to generate information submitted to the OFCS entity. The PCEF entity executes the rules provided by the PCRF entity to control the traffic flow, the accounting of traffic volume and the charging. The PCEF entity may relate to the PCRF entity a change of state of a service flow, as in the case of loss of radio coverage of the mobile. The PCRF entity may receive a session request from the AF (Application Function) entity as in the case of the establishment of a voice or conversational video communication initialized at the IMS network. The PCRF entity may provide the AF entity information about events occurring in the mobile network as in the case of loss of radio coverage of the mobile. In case of roaming, PCEF entity located in the visited network requests rules to the Visited-PCRF (V-PCRF) entity, which gets them from the Home-PCRF (H-PCRF) entity. 1.5.2. Protocol architecture The Gx interface is the reference point between the PCRF and PCEF entities. This interface supports the DIAMETER signaling. Network Architecture The Rx interface is the reference point between the PCRF entity and the AF entity, represented by the P-CSCF entity as in the case of the IMS network. This interface supports the DIAMETER signaling. The Gy interface is the reference point between the PCEF and OCS entities. This interface supports the DIAMETER signaling. The Gz

interface is the reference point between the PCEF and OFCS entities. This interface supports the DIAMETER signaling. The S9 interface is the reference point located between the H-PCRF entity located in the home network and the V-PCRF entity located in the visited network. This interface supports the DIAMETER signaling. The Sp interface is the reference point between the PCRF and SPR entities. The protocol used in this interface is not defined. 1.6. DIAMETER routers DIAMETER agent is a DIAMETER router that can reduce the meshing of DIAMETER sessions between different nodes located, on the one hand, in the entities of EPS or IMS networks, and, on the other hand, in the PCC, OCS and OFCS functions and in the HSS and SLF database (Figure 1.11). Databases Charging Roaming interface Figure 1.11. DIAMETER routers VoLTE and ViLTE DIAMETER routing is done on the basis of the operator's domain name to obtain the IP address of the next hop and on the basis of the identity of the destination to obtain the IP address of the DIAMETER node. DIAMETER routing agent (DRA) only performs routing DIAMETER messages and does not analyze the content of DIAMETER messages. The DRA router is deployed in the home network of the operator. DIAMETER edge agent (DEA) performs the routing of DIAMETER messages and control of their content according to rules established by the operator. The DEA router is deployed at roaming interfaces between the visited network and the home network. 1.7. ENUM system The ENUM mechanism allows for using the phone number (E.164 or TEL URI) to determine the network of the called. The ENUM mechanism is based on domain name system (DNS) resolution which converts the E.164 identity or TEL URI to a SIP URI identity containing the domain name of the destination network. The ENUM system is structured in three levels of servers: - level 1: these servers contain pointers to the level-2 servers. The DNS level-1 server manages the e164enum.net domain. The response to the request relating to a phone number contains the identit

y of the DNS server that handles the country where the mobile is registered; - level 2: these servers have authority over the country code and contain pointers to the level-3 servers. The DNS level-2 servers manage the <country code> e164enum.net domain. The response to the request relating to a phone number contains the identity of the operator's DNS server that handles the mobile; - level 3: these servers have authority over the codes assigned to operators and subscribers. The response to the request relating to a phone number contains the SIP URI of the mobile identity. Network Architecture 1.8. IPX network The internet protocol exchange (IPX) network provides the interconnection between mobile network operators A mobile network requires only a single connection to an IPX network to be able to interconnect with other networks of fixed and mobile operators. IPX network can offer several types of services: - transport service which is to route IP packets; - proxy service which is to route DIAMETER messages, to route SIP signaling messages and to switch RTP streams; - virtual roaming service that allows an operator to replace multiple bilateral roaming agreements by a single agreement with the virtual roaming operator; - ENUM database service by taking into account the level-1 DNS server that manages the e164enum.net domain. Signaling Protocols 2.1. NAS protocol The non-access stratum (NAS) protocol is the signaling exchanged between the user equipment (UE) and the mobility management entity (MME). The NAS protocol is transported by the radio resource control (RRC) protocol over the radio interface LTE-Uu and by the S1-AP (Application Part) protocol over the S1-MME interface. The NAS protocol comprises the following two protocols: - EPS mobility management (EMM): this takes care of controlling mobility and security; - EPS session management (ESM): this controls the bearer establishment. From the point of view of the MME entity, the mobile can be in one of two operational states: EMM-REGISTERED or EMM-DEREGISTERED

. In the EMM-DEREGISTERED state, the mobile location is not known to the MME entity, and therefore, it cannot be contacted. The switch to the registered state takes place when the mobile attaches, which comprises the following four procedures: - mutual authentication of the mobile and the MME entity; - registration of the mobile location with the MME entity; VoLTE and ViLTE: Voice and Conversational Video Services over the 4G Mobile Network, First Edition. André Perez. C ISTE Ltd 2016. Published by ISTE Ltd and John Wiley & Sons, Inc. VoLTE and ViLTE - assignment of the globally unique temporary identity (GUTI) to the mobile; - establishment of the default bearer. The switch to the deregistered state takes place when the mobile detaches or when the attachment of the mobile, the update of its location or the service request are rejected by the MME entity. 2.1.1. EMM messages 2.1.1.1. Attachment and detachment The procedure of attachment is initiated by the mobile in the deregistered state, by sending the message EMM ATTACH REQUEST to the MME entity. This message contains the mobile identity, GUTI or international mobile subscriber identity (IMSI) and the tracking area identity (TAI). The mobile attaches the message ESM PDN CONNECTIVITY REQUEST to establish the default bearer. Upon receiving this message, the MME entity begins the authentication and security procedures for the NAS protocol. If they are successfully completed, the MME entity responds with the message EMM ATTACH ACCEPT, containing a new GUTI, and the message ESM ACTIVATE DEFAULT EPS BEARER CONTEXT REQUEST, to establish the default bearer. The mobile responds with the message EMM ATTACH COMPLETE containing the message ESM ACTIVATE DEFAULT EPS BEARER CONTEXT ACCEPT, to acknowledge the previous message. If the procedures are not successful, the MME entity responds with the message EMM ATTACH REJECT, containing the message ESM PDN CONNECTIVITY REJECT, which causes the mobile to detach. Detachment may be initiated by the mobile or the MME entity by sendin

g the message EMM DETACH REQUEST. Signaling Protocols The response EMM DETACH ACCEPT concludes the detachment procedure. The response is not transmitted by the MME entity if the detach request sent by the mobile indicates that it has been turned off. The detachment procedure implicitly causes the release of the active bearers. 2.1.1.2. Authentication The procedure of mutual authentication is initiated by the MME entity by sending the message EMM AUTHENTICATION REQUEST, containing a random number RAND and the authentication network (AUTN). The mobile uses the RAND received to locally compute its own authentication code RES (Result) and that of the network (AUTN) and compares the AUTN calculated to the one received from the MME entity. If the MME entity is authenticated, the mobile responds with the message EMM AUTHENTICATION RESPONSE, containing the authentication code RES. Otherwise, it indicates that network authentication failed with the message EMM AUTHENTICATION FAILURE. The MME entity compares the RES value received from the mobile with that communicated by the HSS. If the two codes are the same, the mobile is authenticated and the MME entity triggers security mode for NAS signaling. Otherwise, the MME entity responds with the message EMM AUTHENTICATION REJECT. 2.1.1.3. Security mode When mutual authentication has been successful, the MME begins putting the NAS signaling in security mode by sending the message EMM SECURITY MODE COMMAND. The integrity of this message is protected. If the check on the integrity of the message EMM SECURITY MODE COMMAND is positive, the mobile responds with the message EMM SECURITY MODE COMPLETE. All subsequent NAS messages are then encrypted and their integrity is checked. VoLTE and ViLTE If the check on the integrity of the message EMM SECURITY MODE COMMAND is negative, the mobile responds with the message EMM SECURITY MODE REJECT. 2.1.1.4. Tracking area update The procedure of tracking area update is periodically initiated SO that the mobile can maintain its tracking area or

when the mobile has changed its location area. The mobile, in the registered state, sends the message EMM TRACKING AREA UPDATE REQUEST to the MME entity. The MME entity responds either with the message EMM TRACKING AREA UPDATE ACCEPT if it accepts the update, or else with the message EMM TRACKING AREA UPDATE REJECT, indicating the cause of the rejection. If the message EMM TRACKING AREA UPDATE ACCEPT attributes a new GUTI to the mobile, the mobile confirms receipt of this by sending the message EMM TRACKING AREA UPDATE COMPLETE. 2.1.1.5. Service request The service request is sent, when the mobile is in idle mode, to re- establish the default bearers on the LTE-Uu and S1-U interfaces. The service request is initiated by the mobile, by sending the EMM SERVICE REQUEST when signaling or traffic data is waiting. The mobile is notified of awaiting data at the level of the network by way of the paging procedure. The MME entity may reject the request, in which case it responds with the message EMM SERVICE REJECT. This response causes the switch of the mobile to the deregistered state. 2.1.2. ESM messages The mobile sends the request to establish the default bearer when the mobile attaches to the MME entity. The establishment request for the dedicated bearer can be transmitted by the network or the mobile. Signaling Protocols The dedicated bearer corresponds to a specific request by the mobile, following for example the establishment of a voice or a conversational video. The dedicated bearer is associated with a particular quality of service, corresponding to a particular QoS class identifier (QCI) which is different to that of the default bearer. Table 2.1 summarizes the ESM messages exchanged for the establishment, modification and release of the default bearer and the dedicated bearer. Establishment of default bearer, initiated by the network Source Message Destination ACTIVATE DEFAULT EPS BEARER CONTEXT REQUEST ACTIVATE DEFAULT EPS BEARER CONTEXT ACCEPT or ACTIVATE DEFAULT EPS BEARER CONTEXT REJECT Establishment of d

efault bearer, initiated by the mobile Source Message Destination PDN CONNECTIVITY REQUEST ACTIVATE DEFAULT EPS BEARER CONTEXT REQUEST or PDN CONNECTIVITY REJECT Establishment of dedicated bearer, initiated by the network Source Message Destination ACTIVATE DEDICATED EPS BEARER CONTEXT REQUEST ACTIVATE DEDICATED EPS BEARER CONTEXT ACCEPT or ACTIVATE DEDICATED EPS BEARER CONTEXT REJECT Modification of dedicated bearer, initiated by the network Source Message Destination MODIFY EPS BEARER CONTEXT REQUEST MODIFY EPS BEARER CONTEXT ACCEPT or MODIFY EPS BEARER CONTEXT REJECT 32 VoLTE and ViLTE Release of dedicated bearer, initiated by the network Source Message Destination DEACTIVATE EPS BEARER CONTEXT REQUEST DEACTIVATE EPS BEARER CONTEXT ACCEPT Establishment of dedicated bearer, initiated by the mobile Source Message Destination BEARER RESOURCE ALLOCATION REQUEST ACTIVATE DEDICATED EPS BEARER CONTEXT REQUEST or ACTIVATE DEDICATED EPS BEARER CONTEXT REJECT or MODIFY EPS BEARER CONTEXT REQUEST Modification of dedicated bearer, initiated by the mobile Source Message Destination BEARER RESOURCE MODIFICATION REQUEST ACTIVATE DEDICATED EPS BEARER CONTEXT REQUEST or MODIFY EPS BEARER CONTEXT REQUEST or DEACTIVATE EPS BEARER CONTEXT REQUEST or BEARER RESOURCE MODIFICATION REJECT Release of dedicated bearer, initiated by the mobile Source Message Destination PDN DISCONNECT REQUEST DEACTIVATE EPS BEARER CONTEXT REQUEST or PDN DISCONNECT REJECT Table 2.1. ESM messages 2.2. RRC protocol The RRC protocol is the signaling exchanged between the mobile and the evolved node base station (eNB) over the LTE-Uu radio interface. Signaling Protocols The RRC protocol performs the following functions: - broadcast of the system information related to the characteristics of the radio interface; - control of the RRC connection: this procedure includes the paging, the establishment, the modification and the release of the signaling radio bearer (SRB) and the data radio bearer (DRB). It also includes the activation of security mode over the LTE

-Uu interface, the procedure for which includes putting mechanisms in place to encrypt the traffic and RRC signaling flows, and to control the integrity of the RRC signaling flows; - control of handover: this procedure executes the changing of cell between two eNB entities (intra-system handover) or between an eNB entity and a base station from a second- or third-generation mobile network (inter- system handover); - measurement reporting: the eNB entity can trigger measurements carried out by the mobile, either periodically or on demand, to prepare for handover; - transport of the NAS messages exchanged between the mobile and the MME entity. From the point of view of the eNB entity, the mobile may be in one of two operational states: idle mode (RRC_IDLE) or connected mode (RRC_CONNECTED). In idle mode, the mobile is not known to the eNB entity. It remains in this state until the RRC connection setup procedure is completed. The setup procedure is triggered by the mobile when it wishes to transmit traffic or signaling data, the mobile being used the SRBO bearer. In connected mode, the mobile can transmit and receive signaling and traffic data. The mobile is attributed an identifier which is unique to the cell, the cell radio network temporary identity (C-RNTI). In this state, the mobile uses either the SRB1 bearer for RRC messages with possible associated NAS messages, or the SRB2 bearer for RRC messages transporting solely NAS messages. Table 2.2 summarizes the type of SRB, the mode of radio link control (RLC) protocol and the channels used by the different RRC messages over the radio interface. VoLTE and ViLTE MasterInformationBlock Transport Physical RLC mode Logical channel channel channel Not available SystemInformationBlock RLC mode Transport Physical Logical channel channel channel Not available DL-SCH PDSCH Paging Transport Physical RLC mode Logical channel channel channel Not available PDSCH ConnectionSetup ConnectionReject ConnectionReestablishment ConnectionReestablishmentReject Transport Physical RLC mo

PDSCH ULInformationTransfer( (2) Transport Physical RLC mode Logical channel channel channel UL-SCH PUSCH ConnectionSetupComplete SecurityModeComplete SecurityModeFailure ConnectionReconfigurationComplete ConnectionReestablishmentComplete MeasurementReport Transport Physical RLC mode Logical channel channel channel UL-SCH PUSCH Table 2.2. RRC messages: 1) transport of NAS messages only, downstream; 2) transport of NAS messages only, upstream 36 VoLTE and ViLTE 2.2.1. System information The information relating to the radio interface is divided between the messages MasterInformationBlock and SystemInformationBlock. These messages are transmitted periodically and a change in these data is notified to the mobile by paging. The MasterInformationBlock message contains the following data: - the bandwidth of the radio signal for the downstream direction (1.4, 3, 5, 10, 15 and 20 MHz); - the system frame number (SFN); - the configuration of the physical channel PHICH of the radio interface. The configuration of this physical channel is defined by the operator. All SystemInformationBlock messages, with the exception of the SystemInformationBlockTypel message, are mapped in a SystemInformation message. Each SystemInformation message contains SystemInformationBlock messages with the same periodicity. The SystemInformationBlockType2 message must necessarily be mapped in the SystemInformation message. The SystemInformationBlockTypel message contains the following data: - the mobile country code (MCC) and mobile network code (MNC) of the mobile network; - the mobile network code (TAC) of the location area. The identity of the TAI is a concatenation of the MCC, MNC and TAC codes. - the E-UTRAN Cell global identifier (ECGI); - the periodicity of the SystemInformation messages and the types of SystemInformationBlock messages that they contain. Table 2.3 shows the data transported by the different types of SystemInformationBlock message. Signaling Protocols Bandwidth in upstream direction SystemInformationBlockType2 Configuration

of physical channels SystemInformationBlockType3 Cell selection parameters SystemInformationBlockType4 EPS neighboring cells, same frequency SystemInformationBlockType5 EPS neighboring cells, different frequency SystemInformationBlockType6 UMTS neighboring cells SystemInformationBlockType7 GSM/GPRS neighboring cells SystemInformationBlockType8 CDMA 2000 neighboring cells SystemInformationBlockType9 Identity of the home eNB (HeNB) SystemInformationBlockType10 Earthquake and tsunami warning system (ETWS) SystemInformationBlockType11 SystemInformationBlockType12 Commercial Mobile Alert System (CMAS) Information related to the MBSFN (MBMS over SystemInformationBlockType13 Single Frequency Network) area Table 2.3. SystemInformationBlock messages 2.2.2. Control of RRC connection The different procedures associated with the control of the RRC connection relate to paging, RRC connection setup, activation of security mode, RRC connection reconfiguration, RRC connection re-establishment and RRC connection release. The Paging message is used by the eNB entity to alert one or more mobiles in the RRC_IDLE state. VoLTE and ViLTE The Paging message also helps to inform the mobile in RRC_IDLE or RRC_CONNECTED state about a change in the system information or about a notification on ETWS transmitted in the SystemInformationBlockType10 and SystemInformationBlockTypel1 messages or CMAS transmitted in the SystemInformationBlockType12 message. The RRC ConnectionRequest message is used by the mobile to request the establishment of an RRC connection. The RRC ConnectionSetup message is used by the eNB entity to configure the SRB1 bearer. The RRC ConnectionSetupComplete message is used by the mobile to confirm the setup of the RRC connection. This message can also transport NAS messages. The RRC ConnectionReject message is used by the eNB entity to reject the request for the RRC connection. Upon receiving the context about the mobile from the MME entity, the eNB entity activates security mode for the RRC messages. The SecurityModeCommand

message is used by the eNB entity to command the activation of security mode on the radio interface. The SecurityModeCommand message is only checked for integrity. The SecurityModeComplete message is used by the mobile to confirm the activation of security mode. The SecurityModeFailure message is used by the mobile to indicate that security mode was unable to be activated. The encryption of the RRC messages will be effective only if the procedure has been successful. Having initiated the security mode activation procedure, the eNB entity begins the activation of the DRB. The RRC messages are encrypted and checked for integrity. The RRC ConnectionReconfiguration message is used by the eNB entity to command a modification of the RRC connection. This message may relate Signaling Protocols to the configuration of the measurements, control of the mobility and configuration of the DRB default bearer. This message can also transport NAS messages. The RRC ConnectionReconfigurationComplete message is used by the mobile to confirm the reconfiguration of the RRC connection. The RRC ConnectionReestablishmentRequest message is used by the mobile to request the re-establishment of the RRC connection. The RRC ConnectionReestablishment message is used by the eNB entity to re-establish the RRC connection. The RRC ConnectionReestablishmentComplete message is used by the mobile to confirm the re-establishment of the RRC connection. The RRC ConnectionReestablishmentReject message is used by the eNB entity to indicate that the reestablishment of the RRC connection has been rejected. The RRC ConnectionRelease message is used by the eNB entity to release the RRC connection. The procedure can also be used to redirect the mobile to a different frequency band. In exceptional cases, the mobile can terminate the RRC connection without alerting the eNB entity. 2.2.3. Measurement report The measurements carried out by the mobile must be in line with the configuration indicated in the RRC ConnectionReconfiguration message transmitted by the e

NB entity. The mobile sends the eNB entity the measurements in the RRC MeasurementReport message. Measurements carried out on the serving cell and neighboring cells are used for the selection of the cell and for the handover. Intra-frequency measurement, essential for mobility, is configured when connecting. 40 VoLTE and ViLTE Inter-frequency and inter-radio access technology (RAT) measurement can also be configured when connecting. As the mobile does not generally have several radio receivers, the inter- frequency and inter-RAT measurement should be performed at intervals arranged in the frame. The configuration of measurements to be performed by the mobile is triggered by the eNB entity in RRC ConnectionSetup, Connection Reconfiguration, ConnectionReestablishment messages. The measurement configurations to perform define the following parameters: - the object that identifies the radio channel; - the event triggering the measurement report; - the combination of objects and events; - the measurement of filtering parameters; - the periodicity of measurements. 2.3. S1-AP protocol The S1-AP protocol is the signaling exchanged between the eNB and MME entities over the S1-MME interface. The S1-AP protocol performs the following functions: - activation of the context of the mobile by the MME entity; establishment, modification and release of the EPS radio access bearer (E-RAB); - handover management; - paging. This procedure tells the eNB entity that the message needs to be broadcast in the cell; - transport of the NAS signaling exchanged between the mobile and the MME entity; - establishment of the S1-MME interface. Signaling Protocols Table 2.4 summarizes the S1-AP messages sent to paging, context management, bearer management, mobility management, management of the S1-MME interface and NAS messages transport. Function Request Response INITIAL CONTEXT INITIAL CONTEXT SETUP RESPONSE or SETUP REQUEST INITIAL CONTEXT Context management SETUP FAILURE UE CONTEXT RELEASE UE CONTEXT RELEASE COMMAND COMPLETE Function Request

Response E-RAB SETUP / MODIFY E-RAB SETUP / MODIFY REQUEST RESPONSE E-RAB RELEASE E-RAB RELEASE Bearer management COMMAND RESPONSE E-RAB RELEASE INDICATION Function Request Response Paging PAGING Function Request Response HANDOVER REQUIRED HANDOVER COMMAND HANDOVER REQUEST HANDOVER REQUEST ACKNOWLEDGE or HANDOVER FAILURE eNB STATUS TRANSFER Mobility management MME STATUS TRANSFER HANDOVER NOTIFY PATH SWITCH PATH SWITCH ACKNOWLEDGE or REQUEST PATH SWITCH FAILURE VoLTE and ViLTE Function Request Response S1 SETUP RESPONSE S1 SETUP REQUEST S1 SETUP FAILURE ENB CONFIGURATION UPDATE ENB CONFIGURATION ACKNOWLEDGE or UPDATE ENB CONFIGURATION Management of the S1- UPDATE FAILURE MME interface MME CONFIGURATION UPDATE MME CONFIGURATION ACKNOWLEDGE or UPDATE ENB CONFIGURATION UPDATE FAILURE OVERLOAD START OVERLOAD STOP Function Request Response INITIAL UE MESSAGE DOWNLINK NAS Transport of NAS signaling TRANSPORT UPLINK NAS TRANSPORT Table 2.4. S1-AP messages 2.3.1. Context management The context of the mobile has to be established at the level of the eNB and MME entities SO as to transmit the mobile traffic and the NAS signaling as well. The context of the mobile includes the contexts relating to the default bearer, security, capacities of the mobile and roaming restrictions. Context setup for the mobile begins with the INITIAL CONTEXT SETUP REQUEST message transmitted by the MME entity to the eNB entity. This message follows the reception of the INITIAL UE MESSAGE message. Signaling Protocols The MME has to prepare the establishment of the default bearer before receiving the INITIAL CONTEXT SETUP RESPONSE message. This message might contain the cause of the failure to set up the context of the mobile, such as the lack of radio resources. If the eNB is unable to establish the context of the mobile, it responds with the INITIAL CONTEXT SETUP FAILURE message. Release of the context of the mobile is done by way of the UE CONTEXT RELEASE COMMAND message transmitted by the MME entity to the eNB entity, for instance when the mo

bile changes cell. This message is acknowledged in return by the UE CONTEXT RELEASE COMPLETE response. 2.3.2. Bearer management Establishment and modification of the E-RAB dedicated bearer are initiated by the MME entity by sending the E-RAB SETUP/MODIFY REQUEST messages. The eNB entity responds positively or negatively by sending the E-RAB SETUP/MODIFY RESPONSE messages. Release of the dedicated bearer is initiated by the MME entity by sending the E-RAB RELEASE COMMAND message or by the eNB entity by sending an E-RAB RELEASE INDICATION message. Upon receiving this message, the MME entity begins the procedure of release of the dedicated bearer. 2.3.3. Mobility management The decision regarding handover based on the S1 interface is made by the source eNB entity. The phase of handover preparation begins with the sending of the HANDOVER REQUIRED message to the MME entity. When the reservation of resources by the target eNB entity is effective, the MME entity responds with the HANDOVER COMMAND message. VoLTE and ViLTE The MME entity directs the target eNB entity to reserve the radio resources using the HANDOVER REQUEST message. If the operation is successful, the target eNB entity responds with the HANDOVER REQUEST ACKNOWLEDGE message. This message can contain the elements for construction of a GTP-U tunnel to transfer the received data from the source eNB entity to the target eNB entity SO they can be transmitted to the mobile. If not, the target eNB entity responds with the HANDOVER FAILURE message. The source eNB entity has to transfer the value of the field sequence number (SN) of the packet data convergence protocol (PDCP) to the target eNB entity to preserve the continuity of the PDCP frame numbering. This operation is done by the transmission of the following messages: - eNB STATUS TRANSFER from the source eNB entity to the MME entity; - MME STATUS TRANSFER from the MME entity to the target eNB entity. This procedure applies only to bearers who use the acknowledgment mode (AM) of the RLC protocol, which is not

the case of a dedicated bearer for voice or video. When the execution of the handover has been completed, the target eNB entity advises the MME entity of this by way of the HANDOVER NOTIFY message. Regarding handover based on the X2 interface the PATH SWITCH REQUEST message is transmitted by the target eNB entity to the MME entity for the transfer of the extremity of the GTP-U tunnel corresponding to the source eNB entity to the target eNB entity. The MME responds with the PATH SWITCH ACKNOWLEDGE message if the response is positive or with PATH SWITCH FAILURE message if not. Signaling Protocols 2.3.4. S1-MME interface management The eNB entity takes the initiative to activate the S1-MME interface by transmitting the S1 SETUP REQUEST message, indicating the list of serving location area. The S1 SETUP RESPONSE message from MME entity contains information relating to the MME entity such as its code number, the pool number to which it belongs and the MNC and MCC codes. The MME entity may respond negatively with the S1 SETUP FAILURE message. Updates to the information about the eNB entity (or the MME entity respectively) are transmitted by the ENB CONFIGURATION UPDATE message (or the MME CONFIGURATION UPDATE message respectively). These messages receive a positive response with the ENB/MME CONFIGURATION UPDATE ACKNOWLEDGE messages or a negative one with the ENB/MME CONFIGURATION UPDATE FAILURE messages. The MME entity notifies the eNB entity of the beginning (or the end respectively) of a state of overload by the OVERLOAD START message (or OVERLOAD STOP message respectively) SO as to avoid being selected for the attachment of a new mobile. 2.4. X2-AP protocol The X2-AP protocol is the signaling exchanged between two eNB entities over the X2 interface. The X2-AP protocol performs the following functions: - mobility management: this function enables the source eNB entity to transfer the connection of a mobile to the target eNB entity; - load management: this function is used by the eNB entities to provide an indication

of the load of the cells that they serve; - X2 interface management: this function is used for the activation of the X2 interface, the reconfiguration and re-initialization of the X2 interface. 46 VoLTE and ViLTE Table 2.5 summarizes the X2-AP messages exchanged for mobility management, load management and X2 interface management. Function Request Response HANDOVER REQUEST ACKNOWLEDGE or HANDOVER REQUEST HANDOVER PREPARATION FAILURE Mobility management SN STATUS TRANSFER UE CONTEXT RELEASE HANDOVER CANCEL Function Request Response LOAD INFORMATION RESOURCE STATUS RESOURCE STATUS RESPONSE or Load management REQUEST RESOURCE STATUS FAILURE RESOURCE STATUS UPDATE Function Request Response X2 SETUP RESPONSE or X2 SETUP REQUEST X2 SETUP FAILURE ENB CONFIGURATION UPDATE X2 interface management ENB CONFIGURATION ACKNOWLEDGE or UPDATE ENB CONFIGURATION UPDATE FAILURE RESET REQUEST RESET RESPONSE Table 2.5. X2-AP messages 2.4.1. Mobility management The function of mobility management contains the following elementary procedures: - handover preparation; - transfer of the state of the SN field of the PDCP protocol; Signaling Protocols - deactivation of the context of the mobile; - handover cancellation. The procedure of handover preparation is initiated by the source eNB entity by transmission of the HANDOVER REQUEST message to the target eNB entity. The target eNB reserves the resources and responds with the HANDOVER REQUEST ACKNOWLEDGE message. This message contains the value of the tunnel endpoint identifier (TEID) used by the GTP-U protocol for the traffic transferred by the source eNB entity to the target eNB entity. If the resources are unavailable, the target eNB entity sends back the HANDOVER PREPARATION FAILURE message. The procedure of transfer of the state of the SN field consists of transferring to the eNB entity the value of the SN of the PDCP protocol with the SN STATUS TRANSFER message. At the source eNB entity, this message stops the attribution of the SN of the PDCP protocol for the downstream direction. T

he procedure for context release of the mobile is initiated by the target eNB entity by sending the UE CONTEXT RELEASE message to the source eNB entity. Upon receiving this message, the eNB entity eliminates the context of the mobile. The procedure for cancelling the handover is initiated by the source eNB entity with the HANDOVER CANCEL message. This message causes the target eNB entity to release the resources on the radio interface. 2.4.2. Load management The function of load management includes the following elementary procedures: - cell-load indication; - initialization of resource status reports; - resource status reporting. VoLTE and ViLTE The procedure for indication of the load of the cell is initiated by either of the eNB entities with the LOAD INFORMATION message. This message may contain the following elements of information: - interference overload indication (IOI): this information relates to the interference detected by the eNB entity, for the upstream direction. The eNB entity receiving this information has to decrease the interference transmitted by the mobile; - high interference indication (HII): this information relates to the interference detected by the eNB entity, for the upstream direction, indicating which bandwidths are affected. The eNB entity receiving this information needs to avoid using the said bandwidth, for the upstream direction, for the mobiles located on the periphery of the cell; - relative narrowband Tx power (RNTP): this information relates to a decrease in the power transmitted by an eNB entity. The eNB entity receiving this information includes it in its traffic management mechanism. The procedure for initialization of resource status reporting is initiated by either of the eNB entities with the RESOURCE STATUS REQUEST message. The eNB receiving this message responds with the RESOURCE STATUS RESPONSE message, which may contain status information for the radio resources, the S1 interface and the load of the eNB entity. The eNB entity may respond with the RESOURCE STATUS FA

ILURE message if the reports cannot be generated. The resource status report is then transmitted periodically by the eNB entity by sending the RESOURCE STATUS UPDATE message. 2.4.3. X2 interface management The X2 interface is set up with the intention of exchanging the configuration data necessary for both eNB entities to function correctly. One of the eNB entities initiates the procedure by indication of the cells served in the X2 SETUP REQUEST message to a candidate eNB entity. Signaling Protocols The candidate eNB entity responds with the X2 SETUP RESPONSE message, also containing the list of serving cells. The information communicated may also include the list of neighboring cells and the number of antennas for each serving cell. The eNB entity may refuse the establishment of the X2 interface by sending the X2 SETUP FAILURE message in response. The X2 setup is followed by configuration updating of the eNB entity if the configuration of the eNB entity changes. The configuration update is initiated by the ENB CONFIGURATION UPDATE message. The remote eNB entity may respond positively with the CONFIGURATION UPDATE ACKNOWLEDGE message or negatively with the ENB CONFIGURATION UPDATE FAILURE message. The reset of the X2 interface is intended to align the resources of the eNB entities in the case of an unexpected breakdown. The procedure is initiated by the RESET REQUEST message. The receiving eNB entity responds with the RESET RESPONSE message. The procedure does not affect the data exchanged during the X2 setup or the configuration update of the eNB entity. 2.5. GTPv2-C protocol GTP-U (GPRS Tunnel Protocol User) tunnels are used between two entities of the EPS network. Such tunnels enable the traffic data to be compartmentalized. GTP-U traffic tunnels are constructed on the S1-U, S5 and X2 interfaces. The tunnel is identified by the TEID parameter, the IP addresses and the UDP port numbers. The entity receiving the traffic or signaling data determines the value of the TEID parameter which the sending entity has to

The values of the TEID parameter of the GTP-U protocol are exchanged via the GTPv2-C (GPRS Tunnel Protocol Control), S1-AP and X2-AP protocols. VoLTE and ViLTE The TEID parameter used for the signaling exchanged over the S5 interface is unique. The same parameter is used for all signaling messages relating to the activation of the various S5 bearers for the different mobiles. The TEID parameter used for the signaling exchanged over the S10 and S11 interfaces is unique for each mobile. The same parameter is used for all signaling messages relating to the establishment of the various S1-U bearers for the same mobile. Table 2.6 summarizes the GTPv2-C messages exchanged for the management of support and mobility. Type of messages Request Response CREATE / DELETE CREATE / DELETE SESSION REQUEST SESSION RESPONSE CREATE / MODIFY / CREATE /MODIFY / DELETE BEARER DELETE BEARER REQUEST RESPONSE DOWNLINK DATA NOTIFICATION Bearer management DOWNLINK DATA ACKNOWLEDGE or NOTIFICATION DOWNLINK DATA NOTIFICATION FAILURE INDICATION CREATE / DELETE CREATE / DELETE INDIRECT DATA INDIRECT DATA FORWARDING TUNNEL FORWARDING TUNNEL REQUEST RESPONSE Type of messages Request Response FORWARD RELOCATION FORWARD RELOCATION REQUEST RESPONSE FORWARD RELOCATION FORWARD RELOCATION NOTIFICATION ACKNOWLEDGE Mobility management FORWARD ACCESS FORWARD ACCESS CONTEXT CONTEXT NOTIFICATION ACKNOWLEDGE CONTEXT REQUEST CONTEXT RESPONSE CONTEXT ACKNOWLEDGE Table 2.6. GTPv2-C messages Signaling Protocols 2.5.1. Bearer management The signaling bearer related to a mobile is created by the CREATE SESSION REQUEST message. It is reinforced by the use of a TEID parameter. The message is transmitted: - by the MME entity to the serving gateway (SGW), over the S11 interface; - by the target SGW entity for the PDN gateway (PGW), over the S5 interface. The request is transmitted when any of the following procedures are initiated: - attachment of the mobile, - traffic request from the mobile, - updating of the tracking area code (TAC), - handover. The SGW entity (or

respectively PGW entity) responds to the MME entity (or respectively SGW entity) with the CREATE SESSION RESPONSE message. The signaling bearer is deactivated by the exchange of the DELETE SESSION REQUEST/RESPONSE messages. The procedure is triggered when the mobile detaches, when the traffic is released, when the TAC changes, leading to a modification of the SGW entity, or when handover occurs, with a switch of the SGW. The dedicated bearer specific to a mobile is created similarly, modified possibly and deleted by the exchange of the following messages: - CREATE / MODIFY / DELETE BEARER REQUEST; - CREATE / MODIFY / DELETE BEARER RESPONSE. The DOWNLINK DATA NOTIFICATION message is sent by the SGW entity to the MME entity, over the S11 interface. The procedure follows the reception by the SGW entity of data from the PGW entity, with the mobile in ECM-IDLE mode. Just after receiving this message, the MME entity sends the S1-AP PAGING message to the eNB entities belonging to the TAC. VoLTE and ViLTE The MME entity may respond with the DOWNLINK DATA NOTIFICATION ACKNOWLEDGE message, indicating whether or not the request is accepted or with the DOWNLINK DATA NOTIFICATION FAILURE INDICATION message if the mobile does not respond to the paging or if the mobile service request is rejected. The CREATE INDIRECT DATA FORWARDING TUNNEL REQUEST/RESPONSE messages create a specific traffic bearer when handover occurs. This bearer forwards the data traffic received by the source eNB entity to the SGW entity to then be re-transmitted to the mobile via the target eNB entity. 2.5.2. Mobility management Mobility management messages are exchanged between the source and target MME entities, when the handover of the mobile imposes a switch of MME entity. The source MME entity sends the target MME entity the FORWARD RELOCATION REQUEST message containing the context of the mobile. The target MME entity responds with the FORWARD RELOCATION RESPONSE message when the resources needed for the handover have been reserved. The response conta

ins the values of the TEID parameter, which will enable the source SGW entity to redirect the traffic to the target SGW entity during handover. Upon receiving this message, the source MME entity sends the source eNB entity the command to initiate handover. The source MME entity sends the target MME entity the FORWARD ACCESS CONTEXT NOTIFICATION message to provide it with the elements of the context of the E-RAB bearer, such as the PDCP sequence number. The target MME entity sends the source MME entity the FORWARD RELOCATION NOTIFICATION message to indicate that the handover procedure is complete. Signaling Protocols The new MME entity sends the CONTEXT REQUEST message to the former one in the procedure of TAI updating, to retrieve information about the context of the mobile. The former MME entity provides this information in the CONTEXT RESPONSE message, which may contain a positive or negative response. The new MME entity acknowledges this previous message with the message CONTEXT ACKNOWLEDGE. 2.6. SIP protocol Session initiation protocol (SIP) is a control protocol which can establish, modify and terminate multimedia sessions. Media can be added to or removed from an existing session. SIP is based on a request/response pair such as hypertext transfer protocol (HTTP). Each transaction consists of a request, which uses a particular method and one or more responses. 2.6.1. Requests The request begins with a line containing the method, a uniform resource iidentifier (URI) and the version of the protocol. INVITE sip : bob@homeB. net SIP/2.0 2.6.1.1. REGISTER method The REGISTER method is used by an user agent (UA) to notify the REGISTRAR entity of the correspondence between the IP address of the UA entity and URI concerned. This correspondence is necessary for incoming calls. The use of the URI of the REGISTER request, and of the headers To and From, is slightly different to that of other requests. The URI contains only the domain of the REGISTRAR entity, with no part relating to the user. VoLTE and ViLTE The header

To contains the URI of the UA entity which needs to be registered. The header From contains the URI of the entity performing the registration. This entity is generally identical to that of the header To. A UA entity may receive a redirect (3xx) or failure (4xx) response, whose header Contact contains the place where the registrations need to be sent. 2.6.1.2. INVITE method The INVITE method is used by a user agent client (UAC) to establish a dialog or a session. The definitive (positive or negative) responses need to be acknowledged by the ACK request. The INVITE request may contain a message body describing the media that the UAC entity wants to establish. If this description is absent, it needs to be added to the ACK request. The response 200 OK contains the description of the media that the user agent server (UAS) wants to establish. The media are established with the response 200 OK (if the INVITE request contains the description of the media) or with the ACK request (otherwise). A successful INVITE request establishes a dialog between two UA entities, which continues until a BYE request is sent by one of the parties to terminate the session. The dialog is identified by the header Call - ID and the parameter tag of the headers To (parameter specified by the caller) and From (parameter specified by the callee). The headers To and From are respectively specified with the identities of the callee and the caller. Within the dialog, it is possible for each UA entity to transmit one or more requests, with each request initializing a transaction. It is possible to transmit a new INVITE request (reINVITE) within a dialog, for an established session, to update the characteristics of the media. If the reINVITE request is declined, the session continues with the previous characteristics. Signaling Protocols 2.6.1.3. ACK method The ACK method is used to acknowledge a definitive response (2xx, 3xx, 4xx, 5xx and 6xx) to the INVITE request. The ACK request may contain a message body describing the media if this description

is not given in the INVITE request. 2.6.1.4. BYE method The BYE method is used to terminate an established session. A session is considered to be established when the response 2xx is received following the INVITE request. The BYE request is transmitted by either of the UA entities participating in the session. The UAS sends the response back 2xx if the dialog is known, or else sends the response 481 Dialog/Transaction Does Not Exist. 2.6.1.5. CANCEL method The CANCEL method is used to terminate a session which has not yet been successful. It is generated when a provisional response 1xx has been received, but not a definitive response. Upon receiving a CANCEL request, the PROXY SERVER transmits the request to the next hop (a PROXY SERVER or a UA entity) and confirms the cancellation directly to the source with the response 200 OK. A UAS receiving the CANCEL request confirms cancellation with the response 200 OK and terminates the dialog initiated by the INVITE request with a definitive negative response 487 Request Terminated. 2.6.1.6. PRACK method The PRACK method is used to acknowledge the reception of a provisional response (1xx), with the exception of the response 100 Trying. The PRACK request is transmitted when the provisional response received contains the headers CSeq and Rseq. The PRACK request must include the header RAck containing the values of the headers CSeq and Rseq of the provisional response received. VoLTE and ViLTE The provisional response is transmitted at the expiration of a timer until the reception of the PRACK request. The PRACK request is transmitted at the expiration of a timer until the reception of a 200 OK response. 2.6.1.7. UPDATE method The UPDATE method modifies the characteristics of the media in a session which has not yet been successfully established. If the session has successfully been established (the INVITE request has received a 2xx response), the modification of the characteristics of the media is negotiated by the INVITE method (reINVITE). 2.6.1.8. SUBSCRIBE method The

SUBSCRIBE method is used when an UA entity wishes to subscribe to a service whereby he would receive event notifications. The type of event is described in the header Event. The entity which accepts the subscription returns the response 200 OK containing the duration of the subscription in the header Expires. The subscription has to be renewed by transmitting a new SUBSCRIBE request. In the absence of renewal, the subscription terminates automatically. 2.6.1.9. NOTIFY method The NOTIFY method enables an entity to notify the occurrence of an event. This entity needs to receive a response 200 OK which gives the assurance that the request has been properly received. Receipt of the response 481 Dialog/Transaction Does Not Exist automatically terminates the subscription. 2.6.1.10. REFER method The REFER method can be used to transfer media established between two UA entities (e.g. Alice and Bob) to someone else. The REFER request sent by Alice (transferor) to Carol to resume communication. The header Refer-to of the request contains the SIP URI of Bob (transferee). It Signaling Protocols should be noted that in this scenario, communication is not established between Alice and Carol. In a second scenario, Alice establishes an additional communication with Carol. Alice then sends the REFER request to Bob to transfer the communication that she has established with Carol. When Bob notifies her that the transfer has been successful, Alice releases the communication established with Bob. 2.6.1.11. MESSAGE method The MESSAGE method is used to transmit short message service (SMS), contained in a message body, between the two UA entities involved. This message is acknowledged by a response 200 OK. The response must not contain the message body. If the recipient wishes to respond, he must in turn generate a new MESSAGE request. 2.6.2. Responses The response begins with a line containing the version of the protocol, followed by a code for the type of response and a textual description of the code. SIP/2. . 200 OK The different t

ypes of responses are detailed in Tables 2.7 to 2.13. Type of response Description Provisional response Definitive positive response Definitive redirect response Definitive negative response, error due to client Definitive negative response, error due to network Definitive negative response, global error Table 2.7. Types of respones 58 VoLTE and ViLTE Response Description The sender is informed that the SIP message has been 100 Trying received. The caller is informed that the callee is alerted to an 180 Ringing incoming call by a ringing tone. 181 Call Is Being The caller is informed that its call has been Forwarded transferred to a different recipient. 183 Session Progress The caller is informed that its call is being processed. Table 2.8. 1xx-type responses Response Description 200 OK The response acknowledges receipt of the request. The callee has received the request, requiring a 202 Accepted different treatment thereafter Table 2.9. 2xx-type responses Response Description The redirect indicates multiple contacts, the order of 300 Multiple Choices which is significant. 301 Moved Permanent ly The redirect is permanent. 302 Moved Temporarily The redirect is temporary. 305 Use Proxy The redirect is performed to a PROXY SERVER. 380 Alternative Service The redirect points to a different entity (e.g. voicemail service). Table 2.10. 3xx-type responses Signaling Protocols Response Description 401 Unauthorized The REGISTER request requires authentication 486 Busy Here The callee is busy 487 Request The response is transmitted by the UA when it receives Terminated a CANCEL request Table 2.11. 4xx-type responses Response Description An internal error has occurred on the PROXY 500 Server Internal SERVER or the REGISTRAR, SO the request has to Error be repeated later. The gateway to a different network has detected a 502 Bad Gateway fault. 503 Service Unavailable The service is temporarily unavailable. The gateway to a different network cannot relay the 504 Gateway Timeout request because a timer has run out. 505 Version

Not The request is denied because of the version of the Supported The request is denied because the size of the SIP 513 Message Too Large message is too great. Table 2.12. 5xx-type responses Response Description 600 Busy Everywhere The network is saturated. 603 Decline The call is refused. The SIP URI of the callee does not exist 604 Does Not Exist Anywhere anywhere. Some aspects of the session are not 606 Not Acceptable acceptable. Table 2.13. 6xx-type responses 60 VoLTE and ViLTE 2.7. SDP protocol The session description protocol (SDP) gives a description of the flow for which the establishment of the session is implemented by the SIP. The SDP message constitutes the message body attached to the SIP message. It, generally appears in the INVITE request and in the response 200 OK. The parameters which characterize the media flows are as follows: - the type of media (audio, video, data); - the transport protocol (e.g. RTP); - the format of the media (e.g. the type of codec for voice and video); - the IP address to which the media need to be transmitted; - the number of the destination port. The SDP message is a set of lines of code in the format <type>=<value>. The field <type> contains a character (Table 2.14). The content of the field <value> depends on the type. Field <type> Description Version of the protocol <value> = <0> Identifier of the origin and of the session Name of the session <value> = <-> Information about the connection Activity time of the session <valeur> = <0 0> Description of the media Complementary attribute of the media Table 2.14. Structure of SDP message Signaling Protocols 2.8. DIAMETER protocol DIAMETER protocol is used by evolved packet system (EPS), IMS and policy and charging control (PCC) networks to ensure authentication, authorization and accounting. 2.8.1. Application to EPS network Table 2.15 summarizes the DIAMETER messages exchanged over the S6a interface between the MME and HSS entities. Request Response Authentication-Information-Request (AIR) Authentication-Information-Answer

(AIA) Update-Location-Request (ULR) Update-Location-Answer (ULA) Purge-UE-Request (PUR) Purge-UE-Answer (PUA) Insert-Subscriber-Data-Request (IDR) Insert-Subscriber-Data-Answer (IDA) Cancel-Location-Request (CLR) Cancel-Location-Answer (CLA) Delete-Subscriber-Data-Request (DDR) Delete-Subscriber-Data-Answer (DDA) Reset-Request (RSR) Reset-Answer (RSA) Notify-Request (NOR) Notify-Answer (NOA) Table 2.15. DIAMETER messages over S6a interface AIR and AIA messages allow an MME entity to retrieve the authentication data of the mobile (RAND, RES, AUTN and KASME). ULR and ULA messages allow: - to provide the HSS entity with the identity of the MME entity who attached the mobile and information on the mobile; - the MME entity to retrieve the profile mobile data. 62 VoLTE and ViLTE PUR and PUA messages are used to inform the HSS entity that MME entity deleted the mobile profile, after a long period of inactivity. CLR and CLA messages allow the HSS entity to delete the mobile profile stored in the MME entity. IDR and IDA messages allow the HSS entity updating mobile profile stored in the MME entity. DDR and DDA messages allow the HSS entity to remove elements of the mobile profile stored in the MME entity. RSR and RSA messages allow informing the MME entity of a restart of the HSS entity. NOR and NOA messages allow to inform the HSS entity on certain events on the mobile. 2.8.2. Application to IMS network Table 2.16 summarizes DIAMETER messages exchanged over Cx interface between, on the one hand, serving call session control function (S-CSCF) or interrogating-CSCF (I-CSCF), while on the other hand, the HSS entity. The same DIAMETER messages are exchanged over the Dx interface between, on the one hand, the S-CSCF or I-CSCF entities, and, on the other hand, the subscription locator function (SLF). Request Response Multimedia-Authentication-Request (MAR) Multimedia-Authentication-Answer (MAA) Server-Assignment-Request (SAR) Server-Assignment-Answer (SAA) Registration-Termination-Request (RTR) Registration-Termination-Answer

Push-Notification-Answer (PNA) Table 2.17. DIAMETER messages over Sh interface VoLTE and ViLTE UDR and UDA messages allow the TAS entity to retrieve profile data stored in the HSS entity. PUR and PUA messages allow the TAS entity to update the profile data stored in the HSS entity. SNR and SNA messages allow the TAS entity to subscribe to notifications relating to modifications of profile data stored in the HSS entity. PNR and PNA messages allow the TAS entity to receive the notification of modifications in the profile data stored in the HSS entity. 2.8.3. Application to PCC function Table 2.18 summarizes DIAMETER messages exchanged over the Gx interface between policy charging and rules function (PCRF) and policy and charging enforcement function (PCEF) hosted in the PGW entity. Request Response Credit-Control-Request (CCR) Credit-Control-Answer (CCA) Re-Auth-Request (RAR) Re-Auth-Answer (RAA) Table 2.18. DIAMETER messages over Gx interface CCR and CCA messages enable the PCEF entity to solicit the PCRF to: - retrieve the rules to apply to the default bearer created by the EPS network; - inform the PCRF entity to the termination of the session on the EPS network. RAR and RAA messages allow the PCRF entity to solicit the PCEF entity in order to provide the rules to be applied for the dedicated bearer. Signaling Protocols Table 2.19 summarizes DIAMETER messages exchanged over the Rx interface between the PCRF and AF (Application Function) entities. Request Response Authenticate and Authorize Request (AAR) Authenticate and Authorize Answer (AAA) Re-Auth-Request (RAR) Re-Auth-Answer (RAA) Session Termination Request (STR) Session Termination Answer (STA) Abort-Session-Request (ASR) Abort-Session-Answer (ASA) Table 2.19. DIAMETER messages over Rx interface AAR and AAA messages allow the AF entity to provide the characteristics of the media SO that the EPS network can establish the dedicated bearer. RAR and RAA messages allow the PCRF entity to notify the AF entity that a number of IP flows were disabled following a d

eactivation applied at the PCEF entity. STR and STA messages allow the AF entity to inform the session is finished, SO that the EPS network releases the bearer dedicated. ASR and ASA messages allow the PCRF entity to notify the AF entity that session on the EPS network is complete, for example as a result of the loss of coverage of the mobile. DIAMETER messages exchanged over R9 interface between home PCRF (H-PCRF) and visited PCRF (V-PCRF) are identical to the messages exchanged over Gx and Rx interfaces. Table 2.20 summarizes DIAMETER messages exchanged over the Gz interface between the PCEF entity and offline charging system (OFCS). VoLTE and ViLTE The same DIAMETER messages are exchanged over the Rf interface between, on the one hand, the entities of the IMS network, and, on the other hand, the OFCS entity. Request Response Accounting-Request (ACR) Accounting-Answer (ACA) Table 2.20. DIAMETER messages over Gz interface ACR and ACA messages enable the PCEF entity to inform the OFCS entity periodically on the consumption of resources in the case of post-paid service. Table 2.21 summarizes DIAMETER messages exchanged over Gy interface between the PCEF entity and online charging system (OCS). Request Response Credit-Control-Request (CCR) Credit-Control-Answer (CCA) Re-Auth-Request (RAR) Re-Auth-Answer (RAA) Abort-Session-Request (ASR) Abort-Session-Answer (ASA) Table 2.21. DIAMETER messages over Gy interface The same DIAMETER messages are exchanged over the Ro interface between, on the one hand, media gateway control function (MGCF), IMS- GWF (gateway function) and TAS entities of the IMS network, and, on the other hand, the OCS entity. CCR and CCA messages enable the PCEF entity to recover credit from OCS entity in the case of pre-paid service. Signaling Protocols RAR and RAA messages allow the OCS entity to initialize a new authentication or new authorization. ASR and ASA messages allow the OCS entity to end the current DIAMETER session. Basic Procedures 3.1. Attachment At the end of the connection procedure, t

he mobile starts the attachment procedure to the evolved packet system (EPS) which comprises the following steps: - the mutual authentication between user equipment (UE) and mobility management entity (MME) corresponding to the AKA (Authentication and Key Agreement) mechanism; - the security of non-access stratum (NAS) messages; - the location of the mobile related to the tracking area identity (TAI) and to the E-UTRAN cell global identifier (ECGI); - the establishment of a default bearer. In the case where the voice or video conversational call is supported by the EPS network, a default bearer (QCI = 5) is established for transporting the signaling exchanged between the mobile and the IP multimedia sub-system (IMS); - the granting of a globally unique temporary identity (GUTI). The UE mobile attachment procedure to the EPS network is described in Figure 3.1: 1) The attachment procedure is triggered by the UE entity when it sends to the eNB entity the EMM ATTACH REQUEST message containing the international mobile subscriber identity (IMSI) of the mobile. VoLTE and ViLTE: Voice and Conversational Video Services over the 4G Mobile Network, First Edition. André Perez. C ISTE Ltd 2016. Published by ISTE Ltd and John Wiley & Sons, Inc. VoLTE and ViLTE ESM PDN CONNECTIVITY REQUEST EMM ATTACH REQUEST RRC ConnectionSetupComplete S1-AP INITIAL UE MESSAGE DIAMETER AIR DIAMETER AIA EMM AUTHENTICATION REQUEST EMM AUTHENTICATION RESPONSE EMM SECURITY MODE COMMAND EMM SECURITY MODE COMPLETE DIAMETER ULR DIAMETER ULA GTPv2-C CREATE SESSION REQUEST GTPv2-C CREATE SESSION REQUEST DIAMETER CCR DIAMETER CCA GTPv2-C CREATE SESSION RESPONSE GTPv2-C CREATE SESSION RESPONSE ESM ACTIVATE DEFAULT EPS BEARER CONTEXT REQUEST EMM ATTACH ACCEPT S1-AP INITIAL CONTEXT SETUP REQUEST RRC ConnectionReconfiguration RRC SecurityModeCommand RRC SecurityModeComplete ESM ACTIVATE DEFAULT EPS BEARER CONTEXT ACCEPT EMM ATTACH COMPLETE RRC ConnectionReconfiguration Complete S1-AP INITIAL CONTEXT SETUP RESPONSE GTPv2-C MODIFY BEARER REQUEST GTPv2-C MODIFY

BEARER RESPONSE Figure 3.1. Mobile attachment to EPS network The EMM ATTACH message carries the ESM PDN CONNECTIVITY REQUEST message. The EMM ATTACH REQUEST message is carried by the RRC ConnectionSetupComplete message on the LTE-Uu radio interface and the S1-AP INITIAL UE MESSAGE message on the S1-MME interface. Basic Procedures The S1-AP UE INITIAL MESSAGE message contains the identities of TAI and ECGI. 2) Upon receipt of the EMM ATTACH REQUEST message, the MME entity requests the home subscriber server (HSS) entity for the cryptographic data of the mobile in the DIAMETER AIR (Authentication-Information- Request) message. 3) The HSS entity generates cryptographic data using a random number RAND and the key Ki of the mobile and sends them to the MME entity in the DIAMETER AIA (Authentication-Information-Answer) message. The cryptographic data contain the random number (RAND), the mobile authentication code (RES), the network authentication code (AUTN) and the KASME key. The MME entity derives the KASME key to generate the CKNAS, IKNAS and KeNB keys: - the CKNAS key is used to encrypt the NAS message; - the IKNAS key is used to control the integrity of the NAS message; - the KeNB key is transferred to the eNB entity. 4) The MME entity transmits the EMM AUTHENTICATION REQUEST message containing the random number (RAND) and the network authentication code (AUTN) to the mobile. The mobile calculates locally from its secret Ki stored in the universal services identity module (USIM) of its universal integrated circuit card (UICC) and the RAND random number received, the key KASME, its authentication code (RES) and that of the network (AUTN) which it compares to the value received. If the two values are identical, the network is authenticated. 5) The mobile responds to the MME entity with the EMM AUTHENTICATION RESPONSE message containing the RES authentication code. The MME entity compares the RES values received from the mobile and HSS entity. If the values are the same, the mobile is authenticated. VoLTE and ViLTE

6) The NAS signaling security setting is enabled by the MME entity sending the EMM SECURITY MODE COMMAND message controlled with the integrity key IKNAS. This message contains algorithms to derive the KASME key. The mobile derives the KASME key to generate the CKNAS, IKNAS and KeNB keys and checks the integrity of the EMM SECURITY MODE COMMAND message. 7) The mobile responds with the EMM SECURITY MODE COMPLETE message encrypted with the CKNAS key and controlled with integrity key IKNAS. After the mutual authentication phase and the security of NAS messages, the MME entity registers the mobile with the HSS entity. 8) The MME entity sends the DIAMETER Update-Location-Request (ULR) message to the HSS entity to register the mobile and obtain its service profile. The HSS entity records the identity of the MME entity which attached the mobile and the identity of the TAI location area. 9) The HSS entity responds to the MME entity with the DIAMETER Update-Location-Answer (ULA) message that contains the profile of the mobile: - the authorized access point names (APN); - the characteristics of quality of service (QOS) for each default bearer that must be established. The MME entity selects the serving gateway (SGW) entity in its group and the PDN gateway (PGW) entity from a domain name server (DNS) resolution of the APN. 10) The MME entity sends the GTPv2-C CREATE SESSION REQUEST message to create a context at the SGW entity. The GTPv2-C CREATE SESSION REQUEST message contains the IP address of the PGW entity, the APN and the default bearer profile. Basic Procedures 11) The SGW entity sends the GTPv2-C CREATE SESSION REQUEST message to create a context at the PGW entity. The GTPv2-C CREATE SESSION REQUEST message contains the tunnel endpoint identifier (TEID) that the PGW entity will use at the GPRS tunneling protocol user plane (GTP-U) level for the S5 bearer. 12) The PGW entity sends to the policy and charging rules function (PCRF) the DIAMETER Credit-Control-Request (CCR) message for authorization to open the default b

earer. The PCRF entity compares the profile of the mobile with the rules defined for the network and stored in the subscription profile repository (SPR) database. 13) The PCRF entity responds to the PGW entity by a DIAMETER Credit-Control-Answer (CCA) message containing the rules to be applied to the default bearer (filter parameters and charging mode). 14) The PGW entity responds to the SGW entity by a GTPv2-C CREATE SESSION RESPONSE message which contains the following information: - the TEID identifier that the SGW entity will use at the GTP-U protocol level for the S5 bearer; - the mobile configuration (IP address of the mobile, IP address of its DNS server). 15) The SGW entity responds to the MME entity with a GTPv2-C CREATE SESSION RESPONSE which contains the following information: - the TEID identifier that the eNB entity will use at the GTP-U protocol level for the S1 bearer; - the mobile configuration. 16) The MME entity responds to the mobile with the EMM ATTACH ACCEPT message containing the following information: - the mobile configuration; - its GUTI temporary identity. 74 VoLTE and ViLTE The EMM ATTACH ACCEPT message carries the ESM ACTIVATE DEFAULT EPS BEARER CONTEXT REQUEST message. The EMM ATTACH ACCEPT message is carried by the S1-AP INITIAL CONTEXT SETUP REQUEST message on the S1-MME interface and by the RRC ConnectionReconfiguration message on the LTE-Uu radio interface. The S1-AP INITIAL CONTEXT SETUP REQUEST message allows for the creation of the mobile context at the eNB entity level and contains the following information: - the TEID identifier assigned by the SGW entity; - the QoS parameters; - the Kenb key derived from the KASME key. The eNB entity derives the key for creating the following keys: - the KRRCenc key for RRC message encryption; - the KRRCint key for RRC message integrity control; - the KUPenc key for traffic encryption. The RRC ConnectionReconfiguration message initializes mounting of the data radio bearer (DRB). 17) The eNB entity requests the mobile to secure the radio inte

rface with the RRC SecurityModeCommand message which is controlled with the integrity key KRRCint and contains algorithms that allow the mobile to derive the KeNB key. The mobile derives the KeNB key to generate the keys KRRCenc, KRRCint and KUPenc, and checks the integrity of the RRC SecurityModeCommand message. 18) The mobile confirms the establishment of the keys to the eNB entity with the RRC SecurityModeComplete message which is controlled with the integrity key KRRCint. The messages of the last two steps are interposed between the reception of the S1-AP INITIAL CONTEXT SETUP REQUEST message and the Basic Procedures transmission of the RRC ConnectionReconfiguration message by the eNB entity. 19) The mobile confirms receipt of the EMM ATTACH REQUEST message by sending the EMM ATTACH COMPLETE message. The EMM ATTACH COMPLETE message carries the ESM ACTIVATE DEFAULT EPS BEARER CONTEXT ACCEPT message. The EMM ATTACH COMPLETE message is carried by the RRC ConnectionReconfigurationComplete message on the LTE-Uu radio interface and by the S1-AP INITIAL CONTEXT SETUP RESPONSE message on the S1-MME interface. The S1-AP INITIAL CONTEXT SETUP RESPONSE message contains the TEID identifier which the SGW entity will use at the GTP-U protocol level for the S1 bearer. The RRC ConnectionReconfigurationComplete message acknowledges the reception of the RRC ConnectionReconfiguration message. 20) The MME entity transfers the TEID identifier received from the eNB entity to the SGW entity in the GTPv2-C MODIFY BEARER REQUEST message. 21) The SGW entity acknowledges the message received by the GTPv2-C MODIFY BEARER RESPONSE message. 3.2. Registration The registration process to the IMS network includes the following steps: - mutual authentication between the mobile and the serving call session control function (S-CSCF); - establishment of an IPSec security association between the mobile and the P-CSCF entity (proxy-CSCF); - registration by the S-CSCF entity of the correspondence between the IP address of the mobile and its uniform

resource identifier (URI); - subscription by the mobile and the P-CSCF entity for mobile registration events; VoLTE and ViLTE - notification by the S-CSCF entity of the events concerning the registration of the mobile. The registration process to the IMS network is shown in Figure 3.2. P-CSCF I-CSCF S-CSCF SIP REGISTER SIP REGISTER DIAMETER UAR DIAMETER UAA SIP REGISTER DIAMETER MAR DIAMETER MAA SIP 401 Unauthorized SIP 401 Unauthorized SIP 401 Unauthorized SIP REGISTER SIP REGISTER DIAMETER LIR DIAMETER LIA SIP REGISTER DIAMETER SAR DIAMETER SAA SIP 200 OK SIP 200 OK SIP 200 OK SIP REGISTER DIAMETER UDR DIAMETER UDA SIP SUBSCRIBE SIP 200 OK SIP SUBSCRIBE SIP 200 OK SIP 200 OK SIP SUBSCRIBE SIP 200 OK SIP SUBSCRIBE SIP 200 OK SIP NOTIFY SIP NOTIFY SIP 200 OK SIP 200 OK SIP NOTIFY SIP 200 OK SIP NOTIFY SIP 200 OK Figure 3.2. Mobile registration to IMS network Basic Procedures 1) Alice's user agent (UA) sends to the P-CSCF entity an initial REGISTER request containing her private identity (alice_private@homeA.net) in the parameter username in the header Authorization. The header To contains the public identity of Alice's UA entity (sip: alice@homeA.net). The header Contact contains the IP address of Alice's UA entity. The header Security-Client contains the parameters defining the security association IPSec established with the P-CSCF entity. The headers Require and Proxy-Require contain the value sec- agree, indicating that the security mechanism based on IPSec is required. The header Proxy-Require is addressed to the P-CSCF entity. The header Require is addressed to the S-CSCF entity in case the request is transmitted directly to it. REGISTER sip:ims.mnc01.mcc208.3gppnetwork.org SIP/2.0 To: <sip:alice@homeA.net> Contact: <sip:192.0.2.101> Authorization: Digest Bername="alice_private@homeA.net" realm=" ims.mnc01.mcc208.3gppnetwork.org ", nonce="", uri="sip:ims.mnc01.mcc208.3gppnetwork.org",response=" Security-Client: ipsec-3gpp; alg=hmac-sha-1-96; spi- - c=23456789; spi-s=12345678; port-c=2468; port-s=1357 Requir

e: sec-agree Proxy-Require: sec-agree 2) The P-CSCF entity transfers the REGISTER message to the I-CSCF (Interrogating-CSCF) entity, including its identity in the header Path. The P-CSCF entity can find the IP address of the I-CSCF entity by doing a domain name system (DNS) resolution on the basis of the domain name of Alice's UA entity. 78 VoLTE and ViLTE The P-CSCF entity provides the type of mobile network and the identity of the cell in the header P-Access-Network-Info. This information is provided by the PCRF entity. The P-CSCF inserts the header Require containing the value path to ensure that the S-CSCF (Serving-CSCF) entity will take account of the header Path. If the S-CSCF entity does not support this header, it sends back a response 420 Bad extension. The P-CSCF entity declares in the parameter integrity-protected of the header Authorization that security has not been established with the UA entity. The P-CSCF entity removes the headers Require and Proxy - Require which contained the sec-agree because IPSec security will be implemented by the P-CSCF entity. REGISTER sip:ims.mnc01.mcc208.3gppnetwork.org SIP/2.0 Path: <sip:pcscf@homeA.net;lr> Require: path Authorization: Digest sername="alice_private@homeA.net" realm=" ims.mnc01.mcc208.3gppnetwork.org",nonce=" , uri="sip:i ims.mnc01.mcc208.3gppnetwork.org ", response="", integrity-protected="no" 3) I-CSCF entity transmits to the HSS entity the DIAMETER UAR (User-Authorization-Request) message to retrieve the list of S-CSCF entities that can be assigned to the UA entity. 4) I-CSCF entity performs the selection of an S-CSCF entity to which it forwards the REGISTER request from the list of S-CSCF entities received in the DIAMETER User-Authorization-Answer (UAA) message. 5) The I-CSCF entity replaces the initial URI (sip:ims mnc01.mcc208.3gppnetwork.org) with that of the S-CSCF (sip:scscf.homeA.net)\: and sends the REGISTER request to the S- CSCF entity selected. REGISTER sip:scscf.homeA.net SIP/2.0 Basic Procedures 6) The S-CSCF entity transmits to the HSS

entity the DIAMETER MAR (Multimedia-Authentication-Request) message to recover the authentication data of the mobile. 7) The S-CSCF entity receives from the HSS entity the DIAMETER MAA (Multimedia-Authentication-Answer) message containing the random number (RAND), the mobile authentication code (RES), the network authentication code (AUTN), the integrity key (IK) and the cipher key (CK) for establishing the IPSec security association. At this stage, the identity of the S-CSCF entity is registered in the HSS entity, and that of the P-CSCF entity in the S-CSCF entity. 8) The S-CSCF entity responds with a 401 Unauthorized message containing the random number (RAND), the network authentication code (AUTN), the integrity key (IK) and the cipher key (CK). The SIP 401 Unauthorized response is transmitted to the I-CSCF entity whose identity is contained in the first Via header. SIP/2.0 401 Unauthorized WWW-Authenticate: Digest t realm="ims.mnc01.mcc208.3gppnetwork.org ", nonce=base 64 (RAND + AUTN + server specific data) algorithm=AKAv1-MD5, ik="00112233445566778899aabbccddeeff". ck="ffeeddccbbaa11223344556677889900" 9) After removing the Via header containing its identity, the I-CSCF entity forwards the response to the P-CSCF entity whose identity is contained in the first Via header. 10) After removing the Via header containing its identity and the keys IK and CK from the header WWW-Authenticate, the P-CSCF entity transfers the response to the Alice's UA entity (or Bob's) whose identity is contained in the first Via header. In the header Security-Server, the P-CSCF entity indicates the parameters of the security association IPSec established with Alice's UA entity. 80 VoLTE and ViLTE SIP/2.0 401 Unauthorized WWW-Authenticate: Digest ealm="ims.mnc01.mcc208.3gppnetwork.org ", , nonce=base64 (RAND + AUTN + server specific data), algorithm=AKAv1-MD5 Security-Server: ipsec-3gpp; q=0.1; alg=hmac-sha-1-96; spi-c=98765432; spi-s=87654321; port-c=8642; port-s=7531 Upon receiving a 401 Unauthorized message, the mobile retrieves