Abstract:
The present invention supports a communication protocol on a wireless communication network to allocate network resources. The radio network controller maintains quality of service (QoS) profiles. A serving node determines the type of application in a communication call and determines a QoS policy it transmits to the radio network. The radio network identifies the QoS profile based on the received policy and allocates network resources before announcing the call to an access terminal.

Description:
RELATED APPLICATION DATA 
     This application is related to U.S. Provisional Patent Application Ser. No. 60/808,233 filed on May 24, 2006, and priority is claimed for this earlier filing under 35 U.S.C. §120. The Provisional Patent Application is also incorporated by reference into this utility patent application. 
    
    
     TECHNICAL FIELD OF THE INVENTION 
     A method for reserving resources on a wireless communication network to decrease call setup time. 
     BACKGROUND OF THE INVENTION 
     The Internet, like so many other high tech developments, grew from research originally performed by the United States Department of Defense. In the 1960s, the military had accumulated a large collection of incompatible computer networks. Computers on these different networks could not communicate with other computers across their network boundaries. 
     In the 1960s, the Defense Department wanted to develop a communication system that would permit communication between these different computer networks. Recognizing that a single, centralized communication system would be vulnerable to attacks or sabotage, the Defense Department required that the communication system be decentralized with no critical services concentrated in vulnerable failure points. In order to achieve this goal, the Defense Department established a decentralized standard communication protocol for communication between their computer networks. 
     A few years later, the National Science Foundation (NSF) wanted to facilitate communication between incompatible network computers at various research institutions across the country. The NSF adopted the Defense Department&#39;s protocol for communication, and this combination of research computer networks would eventually evolve into the Internet. 
     Internet Protocols 
     The Defense Department&#39;s communication protocol governing data transmission between different networks was called the Internet Protocol (IP) standard. The IP standard has been widely adopted for the transmission of discrete information packets across network boundaries. In fact, the IP standard is the standard protocol governing communications between computers and networks on the Internet. 
     The IP standard identifies the types of services to be provided to users and specifies the mechanisms needed to support these services. The IP standard also specifies the upper and lower system interfaces, defines the services to be provided on these interfaces, and outlines the execution environment for services needed in the system. 
     In a typical Internet-based communication scenario, data is transmitted from an originating communication device on a first network across a transmission medium to a destination communication device on a second network. After receipt at the second network, the packet is routed through the network to a destination communication device using standard addressing and routing protocols. Because of the standard protocols in Internet communications, the IP protocol on the destination communication device decodes the transmitted information into the original information transmitted by the originating device. 
     The IP-Based Mobility System 
     The Internet protocols were originally developed with an assumption that Internet users would be connected to a single, fixed network. With the advent of cellular wireless communication systems using mobile communication devices, the movement of Internet users within a network and across network boundaries has become common. Because of this highly mobile Internet usage, the implicit design assumption of the Internet protocols (e.g. a fixed user location) is violated by the mobility of the user. 
     In an IP-based mobile communication system, the mobile communication device (e.g. cellular phone, pager, computer, etc.) can be called a mobile node or mobile station. Typically, a mobile station maintains connectivity to its home network while operating on a visited network. The mobile station will always be associated with its home network for IP addressing purposes and will have information routed to it by routers located on the home and visited networks. 
     Packet-Based Communication Systems 
     In Internet Protocol (IP) networks, the communication process is very different from prior conventional telecommunication systems. In an IP network communication, there is no open switched connection established between the caller and recipient devices. The information being transmitted between the caller and recipient devices is broken into packets of data, and each packet of data is transmitted to the recipient device in pieces. The data packets individually contain routing information to direct each packet to the recipient device. These packets are then reassembled into a coherent stream of data at the recipient device. 
     Code Division Multiple Access (CDMA) is an evolving third generation communication system standard for wireless communication systems that can transmit multimedia services using the packet-based Internet protocol. These CDMA mobile communication systems support multimedia telecommunication services delivering voice such as VoIP (Voice over IP) and data, to include pictures, video communications, and other multimedia information over mobile wireless connections. These types of communications are typically time-sensitive and require high data rate transfers with inherent delays minimized as much as possible. 
     As the capability of the various communication standards have improved, there has been an increasing need for high-speed transmissions and increased user capacity. A new CDMA packet air interface has been developed that offers improvements over earlier CDMA systems by implementing high-speed shared-traffic packet data channels on the forward air-link connection. Recent developments include CDMA-based 1xEV systems operating at 1.25 MHz. The 1.25 MHz carrier delivers high data rates and increased voice capacity. 1xEV is a two-phase strategy. One phase is designated 1xEV-DO, which handles data only. The 1xEV-DO standard provides user with peak data rates of 3.0 Mbits/s. The other phase is 1xEV-DV, for data and voice. Other standards are evolving that also make use of the shared packet channel and multiplex packet communication for high-speed data and voice communication. 
     In the CDMA standard, Mobile Nodes, or Access Terminals (AT), roam within and across cellular communication sites. Each of the sites, or cells, possesses one or more transceivers coupled to a Base Transceiver Station (BTS) onto the communication network. The BTSs are in turn coupled to an Access Network (AN), also known as a Radio Network (RN). As an AT travels across cellular borders, its physical connection to the BTS keeps on changing. An AT can be physically located anywhere on the network or sub-network, and its routing address data will change and require updating on other nodes. Wireless IP networks handle the mobile nature of AT with hand-off procedures designed to update the communication network and sub-network with the location of the mobile node for packet routing purposes. The latency period in these hand-offs can be prohibitively high. Call (or packet data session) setup times can also be excessive as communication pathways across the access network (whether wireline or wireless) are established before transmitting session specific data (e.g., a SIP Invite message) needed to establish a delay sensitive application—such as VoIP, PTT (Push To Talk) and VT (Video Telephony) etc.—session. 
     A new method of call (or packet data session) signaling (for example, SIP signaling) to setup a real-time application session (such as a VoIP, PTT or VT session) in 1xEV-DO can significantly reduce the call setup time. Call (or packet data session) setup time is an important performance indicator for applications like Push-to-Talk (PTT), Voice over IP (VoIP), and Video Telephony (VT). Call (or packet data session) setup is a critical aspect of delay sensitive application (such as VoIP, PTT, and VT etc.) functionality, since call (or packet data session) setup delays can negate the value of the function. Long pauses in walkie-talkie (or voice call) performance adversely impact the versatility to using the function and lead to customer dissatisfaction. Service providers are quite aware of this concern and are insistent that implementing infrastructure minimizes call (or packet data session) setup delays. 
     Applications using wireless technology for data delivery have to explicitly reserve network resources before data can be exchanged to meet unique resource requirements for the content being transmitted. Resource reservation has to be done by the originating and terminating parties for satisfactory communication since various media content have specific requirements in terms of delay and jitter tolerance. The content can be classified as delay sensitive, rate sensitive, time sensitive, or some other quality adversely impacting the communication. The method for reserving and allocating network resources can significantly effect call (or packet data session) setup time. The extra messaging involved in setting up resources prior to initiating media flow increases call (or packet data session) setup times that often fall outside the limits of tolerance. 
     In the invention, the RNC learns the nature of the content from the requests reserved by the originator of media, and sets aside resources a priori for the terminating end without waiting for a request (from the terminating AT). This earlier reservation or allocation of resources at the terminating end without a request provides immense savings in call (or packet data session) setup times, which is critical for successful deployment of essential services such as PTT, VoIP, and VT, etc. Since resource availability is known during the early stages of call (or a packet data session) setup, the certainty of the stability of established calls (or packet data sessions) can be assured with a higher degree of success. 
     Prior art approaches have not been successful. An optimistic approach to call (or packet data session) setup has been proposed as a predictive scheme. This method involves the delivery of a call (or packet data session) announcement as a general broadcast along with an indication that resources have been allocated beforehand. This allotment is made without a localized view of resource availability or knowledge of which paging sector the AT may respond on. Once the location of the AT is known through its response, subsequent resource allocation attempts by the network on a specific channel within the location sector may fail, causing the call (or packet data session) attempt to abort. Furthermore, this predictive approach is not scalable because it can only be used over a limited number of paging sectors and requires the RN to become content aware. The range limitation of paging sectors covered decreases the first page success rate, destroying the benefits of predictive resource allocation. Content awareness is also computing resource intensive and may adversely impact performance indicators across all applications. There is a need for a new method of resource allocation that reduces latency and speeds up call (or packet data session) setup in time sensitive applications such as PTT, VoIP, and VT, which have stringent constraints on call (or packet data session) set up delays. 
     SUMMARY OF THE INVENTION 
     Upon receiving call setup signaling and resource reservation requests from the originating user, the Radio Network Controller (RNC) linked to the Radio Network (RN) has enough information to identify a Quality of Service (QoS) profile, which is used to deliver content and signaling for that specific application (such as VoIP, PTT, and VT etc.) session. The RNC maintains an abstract data type that associates a call-in-progress with a QoS profile as soon as call processing begins. A serving node (such as PDSN in 3GPP2 network) on the system determines the application based on attributes in the packet and transmits a QoS indicator value (associated with its QoS profile) to the RNC. The RNC retrieves a QoS profile based on the QoS indicator value present in the packet. After the terminating AT entity has been paged (i.e., located in a specific RN sector), the RNC reserves resources for completing the call before announcing the call to the AT based on the generated QoS profile. Setup time is considerably reduced by avoiding the resource request/grant handshaking at the terminating AT side. 
     This method described improves performance indicators such as call setup latency. Certain applications such as PTT, VoIP and VT have stringent constraints on call set up delays and this approach allows the network to guarantee call setup within a very narrow time constraint. Prior art approaches grant connectivity optimistically to reduce setup times. This approach guarantees the connection and at the same time minimizes messaging to complete call setup much quicker than conventional optimistic approaches. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The objects and features of the invention will become more readily understood from the following detailed description and appended claims when read in conjunction with the accompanying drawings in which like numerals represent like elements and in which: 
         FIG. 1  is a schematic diagram of the functional elements of a wireless communication network compatible with the invention based on an implementing architecture for a CDMA system; 
         FIG. 2  is a message flow diagram implementing the invention on the CDMA architecture; and 
         FIG. 3  shows details of a modified message used by the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  shows a CDMA wireless telecommunications system compatible with the invention. The IP based network  3  is coupled to a PDSN  60  via communication link  12  and to another PDSN  61  via communication link  72 . The PDSN  60  and PDSN  61  are also connected to RNC  10  and RNC  70  via communication links  11  and  71 , respectively. The RNC  10  is in turn coupled to a Radio Network (RN)  20 , supporting wireless communications within a paging zone  2 , via communication line  21 . The RN  20  is coupled to an Access Terminal (AT)  30  via wireless communication link  29 . The RN  20  supports communication within a cell site configured into one or more paging zones  2 . The RNC  70  is in turn coupled to a Radio Network (RN)  80 , supporting wireless communications within a paging zone  8 , via communication line  81 . The RN  80  is coupled to an Access Terminal (AT)  90  via wireless communication link  89 . The RN  80  supports communication within a cell site configured into one or more paging zones  8 . 
     The CN  1  consists of a Home Subscriber Server (HSS)  35  coupled to the Call Session Control Function (CSCF)  50  and Application Server (AS)  45  connected to each other via a bus line  9 . The bus line  9  is also connected to a router  40 . Both the bus  9  and the router  40  are part of communication network that may use protocols such as ATM, MPLS, IP, Ethernet etc. The router  40  is connected to the IP based network  3  via the communication link  4 . The AS  40  may either be a VoIP server, or a PTT server, or a VT server or a combination thereof. 
     The data transmission between the PDSN  60  and RNC  10  flows through communication link  12 , thereby permitting communication between the RN  20  and the PDSN  60 . The data transmission between PDSN  61  and RNC  70  flows through communication link  71 , thereby permitting communication between the RN  80  and the PDSN  61 . Data transmission between the CN  1  and PDSN  60  flows through the communication links  4  and  12  via the IP based network  3 . Similarly, data transmission between the CN  1  and PDSN  61  flows through the communication links  4  and  72  via the IP based network  3 . The RNC  10  communicates the session specific QoS requirements to RN  20  and instructs it to allocate necessary RF (Radio Frequency) resources to support wireless communications to the AT  30 . The RNC  70  communicates the session specific QoS requirements to RN  80  and instructs it to allocate necessary RF resources to support wireless communications to the AT  90 . 
     The invention is aimed toward reserving resources to support communications between the AT  30  and the CN  1  broadly and the IP based network  3  specifically. This communication can also take place between the AT  30  and AT  90  via the CN  1  and/or the IP based network  3 . The first step is to identify the application (such as VoIP, PTT, and VT etc.) associated with the transmitted data. The PDSN  60  identifies the application (such as VoIP, PTT, and VT etc.) based on various characteristics of the incoming data packets. These include the source IP address, the destination IP address, the IP flow identification, the Differentiated Services Code Point (DSCP) values in the packet header (which specifies a per-hop behavior applied to the packet), source port number, destination port number, and other packet/policy attributes. The packet/policy attributes are configured in the PDSN  60  by the operators based on the unique packet filtering criteria associated with each application (such as VoIP, PTT, and VT etc.). The PDSN  60  is configured with a policy value to identify the application (such as VoIP, PTT, and VT etc.) associated with an incoming IP packet that is destined toward the AT  30 . The PDSN  60  inserts the policy value into the Generic Routing Encapsulation (GRE) header and/or on the DSCP value of the IP header associated with the application (identified earlier based on the packet/policy attributes). This policy value will specify the QoS resource requirements for the specific IP packet. Although in the preferred embodiment, the PDSN  60  performs these functions, they could be performed by the AS  45 , CSCF  50 , router  40 , a gateway, or another server node in the CN  1 . 
     The second part is to allocate QoS resources. Upon receiving call (or packet data session) setup signaling and resource reservation requests from the originating user, the RNC  10  has enough information to generate a QoS profile required to deliver content and signaling for this specific application (such VoIP, PTT, and VT etc.) session. Based on the QoS requirements for the application (such VoIP, PTT, and VT etc.) represented by the inserted policy value, as configured by the operator of the network, the RNC  10  allocates the required QoS resources to set up the application (such as VoIP, PTT and VT etc.) session. The RNC  10  maintains an abstract data type that associates a session-in-progress with the QoS profile associated with the policy value. Once the terminating entity, the AT  30 , has been paged and located, the RNC  10  sets up or reserves the required RAN resources for completing the application (such as VoIP, PTT and VT etc.) session before announcing the application (such as VoIP, PTT, and VT etc.) session (e.g., a SIP Invite message) to the terminating side. After the RNC  10  receives a response message (such as the “Connection Request+Route Update” message for the CDMA HRPD wireless technology) from the terminating AT  30 , it explicitly reserves resources on the terminating side (e.g. the AT  30 ) by requesting air-link resources that are based on the QoS profile requested by the originating side (e.g. the AT  90 , the CN  1  etc.). Call (or a packet data session) setup time is considerably reduced by avoiding the resource request/grant handshaking at the terminating side. Lack of resource availability can be translated into aborting the call sooner without degrading network utilization. 
       FIG. 2  shows a message flow implementing the invention. Referencing the CDMA network of  FIG. 1 , in step  103 , the RNC transmits a page message and application (such as VoIP, PTT and VT etc.) session specific data to the RN. At this point, the RNC has the QoS profile requested by the originating side and forwards the QoS profile to the RN. In step  105 , the application (such as VoIP, PTT and VT etc.) session specific data is buffered, and the page message is forwarded to the AT in step  106 . The AT processes the page and waits for the access cycle to complete in step  107 . In step  109 , an Access Channel (ACH) probe request is sent by the AT containing both a Connection Request (CR) packet and a Route Update (RU) message packet. In step  111 , the RN processes the ACH probe, and forwards the ACH probe to the RNC, which processes the probe at step  15 . The RNC makes appropriate RAN resource reservations based on the QoS profile once the AT responds. In step  117 , the RNC requests the RN for the required software/hardware and RF resources (such as scheduler queues within the RN&#39;s computing entities, MAC indices etc.). The RN allocates the requested software/hardware and RF resources in step  119 . If the network resources are not available at this point, only application (such as VoIP, PTT and VT etc.) session specific data (e.g., a SIP Invite) is forwarded to the AT without allocating the required QoS specific RAN resources. The AT then explicitly requests resources as in the general case. In step  121 , the RN informs the RNC that all of the requested software/hardware and RF resources have been secured by sending an ACK (e.g. an ACK for software/hardware and RF resources allocation) message. The RN, at the same time, transmits the application (such as VoIP, PTT and VT etc.) session specific data (e.g., a SIP Invite) data and a RAN QoS resource allocation confirmation (e.g. the Forward and Reverse ReservationOn message in CDMA HRPD technology) message to the AT in step  123 . The RAN QoS resource allocation confirmation (e.g. the Forward and Reverse ReservationOn message) message packet indicates that the RNC has allocated the necessary RAN resources required to provide the desired QoS for this application (such as VoIP, PTT and VT etc.) session on both the originating and terminating sides. In step  125 , the AT processes the application data, and in step  126 , the AT waits for the access cycle to be completed. 
     In step  127 , the RNC processes the ACK (e.g., an ACK for software/hardware and RF resources allocation) message received from the RN in step  121 . The RNC then requests the RN to open a traffic channel by sending a traffic channel initiation (e.g. an OpenTC) message at step  129 . In step  131 , the RN processes the traffic channel initiation (e.g. an OpenTC) message and transmits an acknowledgement message (e.g., an OpenTCACK) to the RNC in step  133 . The RNC processes this response in step  135 . In step  137 , the RNC instructs the RN to assign a traffic channel to the AT by sending the appropriate channel assignment (e.g., a traffic channel assignment or TCA) message, and this message (e.g., a TCA) is processed by the RN in step  139 . The traffic channel is assigned by forwarding a traffic channel assignment message (e.g., a TCA) to the AT in step  141 . 
     In step  145 , the AT completes the access cycle and transmits an acknowledgement to the application (such as VoIP, PTT and VT etc.) session specific message (e.g. a SIP 200 OK) to the RN. The message specified in step  145  can be transmitted over the signaling resources of the RAN (e.g., a reverse DoS in CDMA HRPD technology). While the application (such as VoIP, PTT and VT etc.) session specific message is shown (in  FIG. 2 ) to be sent by the AT after receiving the traffic channel assignment message (e.g., a TCA), that, however, does not preclude the AT from sending this message at any time between steps  123  and  141 . The RN forwards the application (such as VoIP, PTT and VT etc.) session specific message to the RNC in step  147 . In step  143 , the AT completes processing the traffic channel assignment message (e.g. a TCA). The AT then transmits a Data Rate Control (DRC) message and a Pilot Acquisition message in step  149 . The pilot signal in a wireless network is typically used for the forward link synchronization, coherent detection, soft handoff and for maintaining orthogonality of the AT. 
     In step  151 , the RN acquires a Reverse Traffic Channel (RTC) and transmits the RTC information in a RTC Acquired message to the RNC in step  153 . In step  155 , the RNC processes the RTC acquisition message and transmits an acknowledgment (e.g. an RTC ACK) message to the RN in step  159 . In step  161 , the RN transmits a RTC Acknowledge (e.g., a RTC ACK) to the AT over the Forward Traffic Channel (FTC). In step  163 , the AT processes the RTC acknowledgement (e.g. an RTC ACK) message, and in step  165  transmits a Traffic Channel Complete (TCC) message, a Reservation Accept (ReservationAccept) message, and a Forward Reservation Acknowledgement (FwdReservationAck) message to the RN over the RTC. The RN processes these messages in step  167 . The AT and the RN begin communicating traffic data packets in step  169 . 
       FIG. 3  shows a modified packet data field used by the PDSN in the invention. If a data packet requires reserving resources, the 1×SDB/HRDP Data over Signaling (DoS) Indicator field in the HRPD Interoperability Specification (IOS) standard (e.g. 3GPP2 A.S0008-A or TIA-878-A) is modified to include both urgent and non-urgent packets. The PDSN tags the GRE header in the packet for ‘urgent’ or ‘non-urgent’ 1×SDB or HRPD DoS transmission as shown in  FIG. 3  based on the DSCP value and/or based on another packet filtering mechanism as Traffic Flow Template (TFT) as described by (but not limited to) IS-835 D. 
     The Ethertype (E) value  205  in the GRE header should be set for Unicast (“0”) or Multicast (“1”) (E=0,1). The Type (T 1 ) data field  210  has a value of “000 0001” and designates the packet as a Short Data Indication packet. The Length (L) data field ( 215 ) has a value of 02H. The Indicator (I) data field  220  has a value of “1” indicating the packet as suitable for 1×SDB or HRPD DoS transmission. The value “0” (zero) for the data field  220  has been reserved for future use. The SDI/DoS type data field (T 2 )  225  is assigned a value tagging the packet as ‘urgent’ (“1”) or ‘non-urgent’ (“0”) as well as the policy value indicating the application (such as VoIP, PTT, and VT etc.) and the desired QoS treatment. The policy values for the data field (T 2 )  225  are as follows. 
     0—Non-urgent packet suitable for 1×SDB or HRPD DoS Transmission 
     1—Urgent packet suitable for 1×SDB or HRPD DoS Transmission 
     2—Allocate QoS resources for forward link (from RAN to AT) only 
     3—Delay Sensitive application with low end-to-end delay bound 
     4—Delay Sensitive application with moderate end-to-end delay bound 
     5—Rate Sensitive application with low bandwidth requirement 
     6—Rate Sensitive application with high bandwidth requirement 
     7—Broadcast based application 
     The data fields  230  and  235  are reserved (RES). 
     While the invention has been particularly shown and described with respect to preferred embodiments, it will be readily understood that minor changes in the details of the invention may be made without departing from the spirit of the invention.