PATENT DOCUMENT

Publication Number: US-8737984-B2
Application Number: US-71742907-A
Country: US
Kind Code: B2

Title: WiMAX intra-ASN service flow ID mobility

Abstract:
This invention provides a method, system and apparatus for providing service flow identifier (“SFID”) mobility in a wireless network, which includes generating a structured service flow identifier, the structured service flow identifier having a service flow identifier field and a service flow granularity field, and establishing a level of service flow identifier mobility for the mobile station based on the structured service flow identifier. The structured service flow identifier can further include a multicast field.

Claims:
What is claimed is: 
     
       1. A method for controlling service flow identifier mobility for a mobile station on a wireless network, the method comprising:
 generating a structured service flow identifier, the structured service flow identifier having:
 a service flow identifier field, and 
 a service flow granularity field, the service flow granularity field specifying service flow granularity for at least one backhaul data path, wherein the service flow granularity field has a plurality of different possible values, wherein the plurality of different possible values comprises: a granularity per service flow, a granularity per subscriber station, and a granularity per base station; 
 
 mapping the structured service flow identifier to a connection identifier; 
 in response to acceptance of a handover request at a target base station, remappinq the structured service flow identifier to a target base station connection identifier, the target base station connection identifier identifying a connection between the target base station and the mobile station; and 
 establishing a level of service flow identifier mobility for the mobile station based on the structured service flow identifier. 
 
     
     
       2. The method of  claim 1 , wherein the structured service flow identifier further includes a multicast field. 
     
     
       3. The method of  claim 2 , further comprising assigning a multicast identifier to the multicast field of the structured service flow identifier. 
     
     
       4. The method of  claim 3 , wherein the multicast identifier supports service flow identifier mobility across a plurality of base stations and a plurality of access service network gateways. 
     
     
       5. The method of  claim 1 , further comprising assigning a service flow granularity to the service flow granularity field of the structured service flow identifier. 
     
     
       6. The method of  claim 1 , further comprising commencing a dynamic service flow process to establish a connection for a service flow. 
     
     
       7. An apparatus for controlling service flow identifier mobility on a wireless network, the apparatus comprising:
 communication circuitry for performing communication; and 
 processing hardware coupled to the communication circuitry, wherein the processing hardware is configured to operate with the communication circuitry to:
 generate a structured service flow identifier having at least:
 a service flow identifier field, and 
 a service flow granularity field, the service flow granularity field specifying service flow granularity for at least one backhaul data path, wherein the service flow granularity field has a plurality of different possible values, wherein the plurality of different possible values comprises: a granularity per service flow, a granularity per subscriber station, and a granularity per base station; 
 
 
 map the structured service flow identifier to a connection identifier; 
 in response to acceptance of a handover request at a target base station, remap the structured service flow identifier to a target base station connection identifier, the target base station connection identifier identifying a connection between the target base station and the mobile station; and 
 establish a level of service flow identifier mobility for the mobile station based on the structured service flow identifier 
 establishing a level of service flow identifier mobility for the mobile station based on the structured service flow identifier. 
 
     
     
       8. The apparatus of  claim 7 , wherein a service flow authorizer stores the structured service flow identifier. 
     
     
       9. The apparatus of  claim 7 , wherein the structured service flow identifier further includes a multicast field. 
     
     
       10. The apparatus of  claim 9 , wherein the multicast field is assigned a multicast identifier that supports service flow identifier mobility across a plurality of base stations and a plurality of access service network gateways. 
     
     
       11. A non-transitory, computer memory medium storing program instructions for controlling service flow identifier mobility for a mobile station on a wireless network, wherein the program instructions are executable by a processor to:
 generate a structured service flow identifier, the structured service flow identifier having a service flow identifier field and a service flow granularity field, the service flow granularity field specifying service flow granularity for at least one backhaul data path, wherein the service flow granularity field has a plurality of different possible values, wherein the plurality of different possible values comprises: a granularity per service flow, a granularity per subscriber station, and a granularity per base station; 
 map the structured service flow identifier to a connection identifier; 
 in response to acceptance of a handover request at a target base station, remap the structured service flow identifier to a target base station connection identifier, the target base station connection identifier identifying a connection between the target base station and the mobile station; and 
 establish a level of service flow identifier mobility for the mobile station based on the structured service flow identifier. 
 
     
     
       12. The non-transitory, computer memory medium of  claim 11 , wherein the structured service flow identifier further includes a multicast field. 
     
     
       13. The non-transitory, computer memory medium of  claim 12 , wherein the program instructions are further executable to assign a multicast identifier to the multicast field of the structured service flow identifier. 
     
     
       14. The non-transitory, computer memory medium of  claim 13 , wherein the multicast identifier supports service flow identifier mobility across a plurality of base stations and a plurality of access service network gateways. 
     
     
       15. The non-transitory, computer memory medium of  claim 11 , wherein the program instructions are further executable to assign a service flow granularity to the service flow granularity field of the structured service flow identifier. 
     
     
       16. The non-transitory, computer memory medium of  claim 11 , wherein the program instructions are further executable to commence a dynamic service flow process to establish a connection for a service flow.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is related to and claims priority to U.S. Provisional Patent Application Ser. No. 60/781,938, filed Mar. 13, 2006, entitled WIMAX SERVICE FLOW ID GLOBAL MOBILITY, the entirety of which is incorporated herein by reference. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     n/a 
     FIELD OF THE INVENTION 
     The present invention relates to communication networks, and more particularly to a method, system and apparatus for controlling service flow mobility across broadband wireless access (“BWA”) communication networks. 
     BACKGROUND OF THE INVENTION 
     As the demand for high speed broadband networking over wireless communication links increases, so too does the demand for different types of networks that can accommodate high speed wireless networking. For instance, the deployment of Institute of Electrical and Electronics Engineers (“IEEE”) 802.11 wireless networks in homes and business to create Internet access “hot spots” has become prevalent in today&#39;s society. However, these IEEE 802.11-based networks are limited in bandwidth as well as distance. For example, maximum typical throughput from a user device to a wireless access point is 54 MB/sec. at a range of only a hundred meters or so. In contrast, while wireless range can be extended through other technologies such as cellular technology, data throughput using current cellular technologies is limited to a few MB/sec. Put simply, as the distance from the base station increases, the need for higher transmission power increases and the maximum data rate typically decreases. Accordingly, there is a need to support high-speed wireless connectivity beyond a short distance such as within a home or office. 
     As a result of the demand for longer range wireless networking, the IEEE 802.16 standard was developed. The IEEE 802.16 standards are often referred to as WiMAX or less commonly as WirelessMAN or the Air Interface Standard. These standards provide specifications for fixed broadband wireless metropolitan access networks (“MAN”s) that use a point-to-multipoint architecture (IEEE 802.16d) and combined fixed and mobile broadband wireless access system&#39;s (IEEE 802.16e). The WiMAX Forum and its Network Working Group (“NWG”) are defining the IEEE 802.16 network architecture and recently issued the NWG Stage-3 draft. Such communications can be implemented, for example, using orthogonal frequency division multiplexing (“OFDM”) and orthogonal frequency division multiplexing access (“OFDMA”). OFDM is a multi-carrier transmission technique that has been recognized as an excellent method for high-speed bi-directional wireless data communications. Fundamentally, frequency division multiplexing (“FDM”) uses multiple frequencies to simultaneously transmit multiple signals in parallel. While each sub-carrier is separated by a guard band to ensure that they do not overlap in the ordinary FDM, the sub-carriers in the OFDM are squeezed tightly together in order to reduce the required bandwidth. In fact the neighboring sub-channels are overlapped in OFDM. However, the sub-carriers are orthogonal to each other such that there is no inter-carrier interference (“ICI”). 
     The 802.16 standards support high bit rates in both uploading and downloading from a base station up to a distance of about 30 miles (about 50 km) to handle real-time services and bandwidth-intensive applications such as streaming music and video, video surveillance, voice over IP (“VoIP”), video conferencing and other voice and data formats, e.g., time division multiplexing (“TDM”). A typical WiMAX network provides up to 75 megabit per second (“mbps”) bandwidth and up to a 50 km range. The 802.16 standard defines a media access control (“MAC”) layer that supports multiple physical layer specifications customized for the frequency band of use and their associated regulations. This MAC layer uses protocols to ensure that signals sent from different stations using the same channel do not interfere with each other and “collide”. 
     The 802.16 standards are connection-oriented protocols. Even the management message is based on the preset connection ID (“CID”), which is defined by 802.16 standards as a 16-bit value that identifies a connection to equivalent peers in the MAC of a base station (“BS”) and a mobile subscriber station (“MS”). Each connection is assigned a unique CID that maps to a service flow identifier (“SFID”), which is defined by 802.16 standards as a 32-bit value that uniquely identifies a service flow to both a MS and a BS. A SFID defines the quality of service (“QoS”) parameter set for a service flow associated with a connection. As such, service flow plays a central role in the technology. Each service flow is associated with zero or one connection depending on the operational mode, e.g., unicast, multicast and broadcast. 
     Currently, there is a lack of SFID mobility when a mobile subscriber station (“MS”) attempts to effect a handover from a serving BS to a target BS, especially during handover between a serving BS communicating with one access service network (“ASN”) gateway (“GW”) and a target BS communicating with another ASN GW. Each time there is a handover of a MS, the SFID is recalculated and updated to create a new SFID with respect to the new connection that is established. Several attempts to solve this problem have been proposed. 
     One attempt uses an access service network gateway to assign an ASN GW-wide unique SFID. However, there is no global mobility for this ASN GW-wide unique SFID, nor any multicast service. Another attempt uses a BS assign a BS-wide unique SFID. However, here again, there is no global mobility for this BS-wide unique SFID, and no multicast service within a corresponding ASN GW. 
     It is therefore desirable to have methods and systems to provide global mobility of a SFID across multiple BSs and ASN GWs that can include additional service flow parameters such as multicast service support and backhaul data path (service flow) granularity. 
     SUMMARY OF THE INVENTION 
     It is to be understood that both the following summary and the detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. Neither the summary nor the description that follows is intended to define or limit the scope of the invention to the particular features mentioned in the summary or in the description. 
     This invention provides a method, system and apparatus for controlling service flow identifier mobility on a wireless network, which includes generating a structured service flow identifier, the structured service flow identifier having a service flow identifier field and a service flow granularity field, and establishing a level of service flow identifier mobility for the mobile station based on the structured service flow identifier. 
     In accordance with one aspect, the present invention provides a method for controlling service flow identifier mobility for a mobile station on a wireless network, the method including generating a structured service flow identifier, the structured service flow identifier having a service flow identifier field and a service flow granularity field, and establishing a level of service flow identifier mobility for the mobile station based on the structured service flow identifier. 
     In accordance with another aspect, the present invention provides a method for controlling service flow identifier mobility on a wireless network, which includes retrieving a gateway service flow identifier mobility for a mobile station on a wireless network, a memory for storing data corresponding to at least one structured service flow identifier, and a processor, the processor operating to generate a structured service flow identifier, the structured service flow identifier having a service flow identifier field and a service flow granularity field, and to establish a level of service flow identifier mobility for the mobile station based on the structured service flow identifier. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete understanding of the present invention, and the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein: 
         FIG. 1  is a block diagram of the network architecture of a wireless access network constructed in accordance with the principles of the present invention; 
         FIG. 2  is a block diagram of a service flow authorizer (“SFA”) and a service flow manager (“SFM”) within the network architecture of the wireless access network constructed in accordance with the principles of the present invention; 
         FIG. 3  is a diagram illustrating a format of a structured service flow ID (“SFID”) in accordance with the principles of the present invention; 
         FIG. 4  is a diagram illustrating an IEEE 802.16 standard 4-Byte SFID; 
         FIG. 5  is a flow diagram illustrating a structured SFID management process for global SFID mobility in accordance with the principles of the present invention; and 
         FIG. 6  is a flow diagram illustrating a structured SFID management process for global SFID mobility in accordance with the principles of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawing figures in which like reference designators refer to like elements, there is shown in  FIG. 1 , a system constructed in accordance with the principles of the present invention and designated generally as “ 100 .” System  100  includes base stations  102  (“BS”) and mobile stations  104  (“MS”). Base stations  102  engage in wireless communication with mobile stations  104 . Similarly, mobile stations  104  engage in wireless communication with base stations  102 . 
     Base station  102  can be any base station arranged to wirelessly communicate with mobile stations  104 . Base stations  102  include the hardware and software used to implement the functions described herein to support SFID mobility. Base stations  102  include a central processing unit, transmitter, receiver, I/O devices and storage such as volatile and nonvolatile memory as may be needed to implement the functions described herein. 
     Mobile stations  104  can be any mobile station including but not limited to a computing device equipped for wireless communication, cell phone, wireless personal digital assistant (“PDA”) and the like. Mobile stations  104  also include the hardware and software suitable to support SFID mobility. Such hardware can include a receiver, transmitter, central processing unit, storage in the form of volatile and nonvolatile memory, input/output devices, etc. 
       FIG. 2  shows system  100  with an access service network gateway  108  (“ASN GW”) in communication with base stations  102 A,  102 B in accordance with the principles of the invention (base stations  102 A and  102 B are referred to collectively herein as “base stations  102 ”). The ASN GW  108  provides an aggregation of control plane functions, e.g., mobility, in addition to performing bearer plane routing or bridging functions. The ASN gateway  108  includes the hardware and software suitable to support the MAC control plane functions used to engage in communication with base stations  102 . Such hardware can include protocol translators, impedance matching devices, rate converters, fault isolators, or signal translators as necessary to provide system interoperability. More importantly, the ASN GW  108  provides a number of options for allowing mobility between base stations  102 . For example, ASN GW  108  provides a service flow authorizer (“SFA”)  110  that generates a structured SFID  300  ( FIG. 3 ) that supports SFID global mobility. Structured SFID  300  is discussed below in more detail with respect to  FIG. 3 . These options are functionally implemented within ASN GW  108  as described below. 
     As shown in  FIG. 2 , mobile station  104  engages in bidirectional communication with base stations  102 , which have overlapping coverage regions  22 A,  22 B respectively. The ASN GW  108  supports interfaces such as the WiMAX network reference architecture R6 interfaces, which implement a set of control and bearer plane protocols for communication between the base stations  102  and the ASN GW  108 . The bearer plane includes an intra-ASN data path or inter-ASN tunnel between the base stations  102  and the ASN GW  108 . The control plane includes protocols for IP tunnel management (establish, modify and release) in accordance with the mobile station  104  mobility events. The ASN GW  108  to base stations  102  interface may also serve as a conduit for exchange of media access control (“MAC”) layer state information between neighboring base stations  102 . The ASN GW  108  to mobile station  104  interface may include additional protocols related to the management plane. 
     In this embodiment, a service flow authorizer module  110  (“SFA”) is coupled to the ASN GW  108  and provides the communications network system  100  with the capability to control SFID mobility service by generating a structured SFID for a requested MS  104 . As merely an example, the SFA  110  is referred to as a logical/physical function entity, which authorizes and communicates appropriate service flow actions to the ASN GW  108 .  FIG. 2  also shows service flow manager (“SFM”) modules  114 A and  114 B (collectively referred to herein as “SFMs  114 ”) coupled to BS  102 . SFMs  114  provide for the control of service flows by approving or rejecting a request for a service flow. Typically SFMs  114  will activate a service flow in two phases—admit the service flow first, then activate it. For example, the term SFM is broadly defined and refers to a logical/physical entity configured for the creation, admission, activation, modification and deletion of service flows after getting authorization from an SFA  110  component. In addition, SFMs  114  can activate a service flow immediately or defer activation to a later time. Once a service flow has been admitted, both the BS  102  and MS  104  can reserve resources for that service flow. Resources reserved by the BS  102  and MS  104  are not limited to bandwidth, but can include other resources such as memory. Dynamic changes to the QoS parameters of an existing service flow are also approved by the SFMs  114 . QoS parameter changes are requested with dynamic service flow messages sent between the BS  102  and MS  104 , which are described in more detail with respect to the flow diagram of  FIG. 4 . The SFA  110  and SFMs  114  can be a software implementation, a hardware implementation or a combination of both. 
     Some of the functional units described herein have been labeled as modules, in order to more particularly emphasize their implementation independence. For example, a module may be implemented as a hardware circuit comprising custom circuits or gate arrays, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components. A module may also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices or the like. 
     Modules may also be implemented in software for execution by various types of processors. An identified module of executable code may, for instance, comprise one or more physical or logical blocks of computer instructions, which may, for instance, be organized as an object, procedure, or function. Nevertheless, the executables of an identified module need not be physically located together, but may comprise disparate instructions stored in different locations which, when joined logically together, comprise the module and achieve the stated purpose for the module. 
     A module of executable code could be a single instruction, or many instructions, and may even be distributed over several different code segments, among different programs, and across several memory devices. Similarly, operational data may be identified and illustrated herein within modules, and may be embodied in any suitable form and organized within any suitable type of data structure. The operational data may be collected as a single data set, or may be distributed over different locations including over different storage devices, and may exist, at least partially, merely as electronic signals on a system or network. 
       FIG. 3  is a diagram illustrating a format of a structured service flow ID (“SFID”)  300  in accordance with the principles of the present invention. Structured SFID  300  supports SFID global mobility and includes a 1-byte SFID field  302 , a 1-byte multicast group ID field  304 , a 3-bit service flow granularity (“SFG”) field and a 13-bit reserved field  308 . The 1-byte SFID field  302  supports up to 256 service flows per mobile station (“MS”)  104 . Once a SFID is limited per MS  104 , the 1-byte SFID field is sufficient to represent all service flows for that MS  104 . This advantageously provides for using the other 3 bytes of the designated IEEE 802.16 standard SFID ( FIG. 4 ) for other identifiers such as the multicast group ID and the SFG. The 1-byte multicast group ID field  304  supports up to 256 multicast group IDs per MS  104 . The 1-byte multicast group ID field  304  can be set to zero if the service flow is a unicast service flow. The 3-bit SFG field  306  contains the service flow granularity for the backhaul data paths. In this embodiment, the SFG field  306  defines “000” as the granularity per service flow, “001” as the granularity per subscriber station  104 , and “010” as the granularity per base station  102 . Reserved field  308  can be used for further expansion of structured SFID  300 . 
       FIG. 5  illustrates a flow diagram of a structured SFID management process for facilitating SFID mobility in system  100 . SFA  110  and SFM  114  are in communication with the each other and MS  104 . MS  104  or BS  102  can reserve resources for a service flow by transmitting a resource reservation request message, such as NWG Stage-3 Draft defined RR-REQ to SFA  110  (Step S 100 ). In this embodiment, SFA  110  is part of ASN GW  110  and generates a 1-byte SFID for the requested MS  104 . This newly generated SFID field  302  for the MS is delivered to SFM  114  of BS  102  by a resource reservation request message, such as RR-REQ/SFID (Step S 102 ). SFM  114  of BS  102  maps the SFID  300  having SFID field  302  for MS  104  to the local CID  116 , which can additionally belong to a multicast group with a multicast ID such as “MID”. Multicast ID MID is assigned to the one-byte multicast ID field  304  of structured SFID  300  as SFM  114  updates the multicast ID field  304  of structured SFID  300 . In conjunction with the assigning of the multicast ID field  304 , the backhaul data path can also be established with configured data path service flow granularity (“SFG”) field  306  of SFID  300 . In this embodiment, SFG  306  is defined as “000” for granularity per service flow, “001” for granularity per subscriber and “010” for granularity per BS  102 . 
     At step S 104 , the BS  102  initiates a three-way handshaking process of a dynamic service flow request/response/acknowledge, such as NWG Stage-3 Draft defined DSA-REQ/RSP/ACK, to establish the connection for the service flow with CID  116  (Step S 104 ). During a resource reservation response, such as IEEE 802.16 defined RR-RSP, the newly created 4-byte structured SFID  300  is delivered to SFA  110  (Step S 106 ). SFA  110  can now update the SFID structured data (Step S 108 ). At this point MS  104 , BS  102  and SFA  110  of ASN GW  108  each hold a synchronized 4 byte structured SFID  300  that supports global mobility with multicast support. 
       FIG. 6  is a flow diagram illustrating a structured SFID management process for facilitating SFID mobility in system  100 . In this example, it is assumed that MS  104  has an active current service flow with serving BS (“SBS”)  102 A and has determined that a handover to a target BS (“TBS”)  102 B is desirable. 
     MS  104  transmits a mobile station handover request, such as IEEE 802.16 defined MOB-MSHO-REQ, to SBS  102 A (Step S 200 ). Upon receiving the mobile station handover request, SBS  102 A transmits a handover request, such as IEEE 802.16 defined HO-REQ, to ASN GW  108 , which can check the active structured SFID of MS  104 . In turn, ASN GW  108  transmits a HO-REQ to TBS  102 B (Step S 204 ). Upon receiving the handover request TBS  102 B transmits a handover response, such as IEEE 802.16 defined HO-RSP, which can includes the acceptance of the handover request of MS  104  to TBS  102 B (Step S 206 ), which handover request is transmitted to SBS  102 A via ASN GW  108  (Step S 208 ). At Step S 210 , SBS  102 A transmits a mobile handover response message, such as EE 802.16 defined MOB-MSHO-RSP, to the MS  104  in response to the MOB-MSHO-REQ message (Step S 210 ). 
     Upon receiving the mobile handover response message from SBS  102 A, MS  104  transmits to the SBS  102 A a handover indication message, such as IEEE 802.16 defined MOB-HO-IND, which indicates that the MS  104  will be handed-over to the TBS  208  (Step S 212 ), and can release the call with respect to SBS  102 A. Before releasing the call, SBS  102 A transmits a handover confirmation message, such as IEEE 802.16 defined HO-CONFIRM, to ASN GW  108  (Step S 214 ) which can be relayed to TBS  102 B to (Step S 216 ). At Step S 218 , SFA  110  of ASN GW  108  transmits a resource reservation request message, such as NWG Stage-3 Draft defined RR-REQ to the TBS  102 B. In this case, the resource reservation request message includes the structured SFID data of the present invention for MS  104 . SFM  114 B at TBS  102 B remaps the one byte SFID field  302  of SFID  300  to the newly created connection ID  116  for MS  104 . As the multicast ID MID  304  and the SFG  306  have been added to structured SFID  300 , there is no need to assign a new multicast ID to the service flow. At Step S 220 , TBS  102 B may include CID_Update TLVs in the registration response for MS  104  recognized by TBS  102 B as performing handover or network re-entry by the presence of an unexpired SBS identifier in a ranging request message. In this embodiment CID_Update is a compound type-length-value (“TLV”) element that provides a shorthand method for renewing active connection used by MS  104  in its previous serving BS  102 A. The TLVs specify CID in the TBS  102 B that can replace active CID used in the previous serving BS  102 A. These TLVs enable TBS  102 B to renew connections used in the previous serving BS  102 A. At step S 222 , a resource reservation response, such as NWG Stage-3 Draft defined RR-RSP, carries the structured SFID  300  back to ASN GW  108  and SFA  110  updates the SFID for MS  104 . Now MS  104 , TBS  102 B and ASN GW  108  have the same four byte SFID  300 , which retains a multicast ID  304  and a SFG  306 . 
     In an alternative process, the resource reservation request message of Step S 218  could be carried within the handover request of Step S 204 . Additionally, the resource reservation response message with SFID  300  of Step S 222  could be carried within the handover response of Step S 204 . These alternatives would advantageously reduce the quantity of control messages over the R6 interface. 
     The present invention advantageously provides a method, system and apparatus for providing intra-ASN service flow identifier (“SFID”) mobility in a broadband wireless access (“BWA”) such as an IEEE 802.16 compliant network. Of course, it is understood that the present invention is not limited to IEEE 802.16 compliant wireless networks and that the invention can be implemented in any wireless network that includes the ability to hand off communications with a wireless device among different base stations. 
     The present invention can be realized in hardware, software, or a combination of hardware and software. An implementation of the method and system of the present invention can be realized in a centralized fashion in one computing system or in a distributed fashion where different elements are spread across several interconnected computing systems. Any kind of computing system, or other apparatus adapted for carrying out the methods described herein, is suited to perform the functions described herein. 
     A typical combination of hardware and software could be a specialized or general-purpose computer system having one or more processing elements and a computer program stored on a storage medium that, when loaded and executed, controls the computer system such that it carries out the methods described herein. The present invention can also be embedded in a computer program product, which comprises all the features enabling the implementation of the methods described herein, and which, when loaded in a computing system is able to carry out these methods. Storage medium refers to any volatile or non-volatile storage device. 
     Computer program or application in the present context means any expression, in any language, code or notation, of a set of instructions intended to cause a system having an information processing capability to perform a particular function either directly or after either or both of the following a) conversion to another language, code or notation; b) reproduction in a different material form. In addition, unless mention was made above to the contrary, it should be noted that all of the accompanying drawings are not to scale. Significantly, this invention can be embodied in other specific forms without departing from the spirit or essential attributes thereof, and accordingly, reference should be had to the following claims, rather than to the foregoing specification, as indicating the scope of the invention. 
     It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described herein above. A variety of modifications and variations are possible in light of the above teachings without departing from the spirit or essential attributes thereof, and accordingly, reference should be had to the following claims, rather than to the foregoing specification, as indicating the scope of the of the invention.

Metadata:
Filing Date: 20070313
Publication Date: 20140527
Grant Date: 20140527
Priority Date: 20060313
Inventors: KUANG RANDY
YUAN WENHUI
Assignee: APPLE INC
CPC Classifications: [{"code": "H04L47/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L47/15", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W8/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L47/2441", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W8/26", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W28/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W36/00", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W8/26", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L47/2441", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L47/15", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 38478864