Patent Publication Number: US-2010131667-A1

Title: Executable Communication Protocol Description Method and Apparatus

Description:
BACKGROUND 
     The Open System Interconnection (OSI) reference model describes how information from a software application in one device moves through a network medium to a software application in another device. The OSI reference model is a conceptual model composed of seven layers, each specifying particular network functions. The OSI model divides the tasks involved with moving information between networked devices into seven smaller, more manageable task groups. A task or group of tasks is then assigned to each layer of the OSI model. The uppermost layer is the application layer followed by the presentation layer, session layer, transport layer, network layer, data link layer and the physical layer. Each layer is reasonably self-contained so that the tasks assigned to each layer can be implemented independently. This enables the solutions offered by one layer to be updated without adversely affecting the other layers. Standard communication models conceptually based on the OSI model include TCP/IP, SS7 (Signaling System #7), AppleTalk, SNA (Systems Network Architecture), DSL (Digital Subscriber Line), UMTS (Universal Mobile Telecommunications System), etc. 
     Each layer of a communication model is defined by a specific structure and corresponding protocol. The structure determines how information is arranged or organized at a particular layer, often referred to as a data unit. For example, information is organized as frames at the data link layer, packets at the network layer, segments or datagrams at the transport layer and as data at the session, presentation and application layers in the OSI model. Actual communication is made possible by using communication protocols. In the context of data communication, a protocol is a formal set of rules and conventions that governs how devices exchange information over a communication medium. A protocol implements the functions of one or more of the OSI layers. 
     SUMMARY 
     According to an embodiment, data is transmitted from a first communication device to a second communication device in accordance with one or more communication layer functions of a communication standard including at least a data link layer function. An executable description of at least a new data link layer function is generated at the first communication device. At least the data link layer function of the communication standard is replaced with the new data link layer function at the first communication device. 
     Those skilled in the art will recognize additional features and advantages upon reading the following detailed description, and upon viewing the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an embodiment of communication devices connected over a communication network. 
         FIG. 2  illustrates an embodiment of communication devices connected over a DSL communication network. 
         FIG. 3  illustrates an embodiment of communication devices connected over a UTRAN communication network. 
         FIG. 4  illustrates an embodiment of programmable protocol processors included in communication devices. 
         FIG. 5  illustrates an embodiment of a method for establishing and maintaining a connection between communication devices. 
         FIG. 6  illustrates another embodiment of programmable protocol processors included in communication devices. 
     
    
    
     DETAILED DESCRIPTION 
     In the following, exemplary embodiments are described. The embodiments deal with a more flexible approach to implement data communication. In data communication, the layer structures and protocols often differ from communication standard-to-communication standard. It is hereby to be noted that in the following, “communication standards” may also be referred to shortly as “standards”. For example, ATM (asynchronous transfer mode) cells use a different frame structure with different header bits than Ethernet frames. As such, Ethernet and ATM do not use the same protocol for frame processing. VDSL (very high bitrate DSL) standards use other frame structures than ADSL (Asymmetric DSL) standards. 3GPP (3 rd  generation partnership project) employs a different frame structure than WLAN (wireless local area network). Furthermore, different standards provided by different standardization organization may use different protocols or structures. 
     To comply with a particular communication standard such as ATM, Ethernet, WLAN, 3GPP standards such as UMTS (Universal Mobile Telecommunications System) or LTE (Long Term Evolution), etc., conventional communication devices are designed to conform (i.e., must support) the structures and protocols associated with the standard. The structure and protocol associated with each layer of the standard are standard and determined in advance. For example, PPPOE (point-to-point protocol over Ethernet) has a frame structure with predetermined fields such as source and destination address, PPPOE header, PPP ID, payload, etc. The different fields are located at particular locations within a PPPoE frame. Standardizing the structures and protocols of a communication standard ensures compatibility and interoperability across different device platforms. 
     However, using standard structures and protocols to implement a communication model greatly limits the ability of communication devices to adapt their performance to changing operating conditions in the field. For example, particular channel conditions may warrant a more optimal data link layer frame structure and/or protocol than provided by the standard data link layer frame structure and/or protocol. Higher layers of the communication standard may also benefit from more optimal structures and protocols in view of other operating conditions. However, the performance benefits associated with more optimal layer structures and protocols are not obtainable by conventional communication devices because the devices have little or no flexibility in the way layer structures and protocols are implemented to support a particular communication standard. Using relatively rigid structures and protocols to implement a communication standard prevents devices from implementing more efficient structures and protocols when operating conditions warrant such changes. Realizing the above described problems, in the following embodiments will be described a new and flexible ad hoc approach to data communication protocol handling. 
       FIG. 1  illustrates an embodiment of a host communication device  100  communicatively coupled to a requesting communication device  110  over a communication network  120 . The communication network  120  can be wired, wireless or a combination of both. The requesting device  110  sends requests to the host device  100  for processing and can comprise any type of wired or wireless device capable of communicating with the host device  100 . For example, the requesting device  110  can be a telecommunication modem or a telecommunication management unit in connection with a telecommunication modem, a desktop or portable computer, server, router, network-capable portable electronic device such as a mobile phone, smartphone, portable media player, PDA, etc. or any other type of electronic device capable of network communication. The host device  100  can be any type of wired or wireless device that responds to requests received from the requesting device  110  and can also be a desktop or portable computer, server, network-capable portable electronic device such as a mobile phone, smartphone, portable media player, PDA, etc. or any other type of electronic device capable of network communication. 
     The devices  100 / 110  communicate over the network  120  by establishing a connection with each other in accordance with a wired or wireless communication standard such as xDSL (where x stands for any type of DSL), ATM, Ethernet, WLAN, 3GPP, etc. Each communication device  100 / 110  supports the particular communication standard by implementing one or more communication layers  130  mandated by the standard. For example, the devices  100 / 110  may implement the seven layers of the OSI model or any other model associated with the communication standard. Each layer has a well-defined, standardized structure and protocol that together control how information is organized and processed across the entire communication stack  130 . The standard layer structures and protocols enable the devices  100 / 110  to establish a communication connection between each other in a repeatable and well-controlled manner. However, the standard layer structures and protocols offer little or no flexibility in the way layer functions are defined because the structures and protocols are standardized. 
     After the communication connection is established between the devices  100 / 1   10 , the host device  100  can determine whether a more optimal structure and/or protocol can be implemented at any of the communication layers  130  based on actual operating conditions observed by the host or requesting devices  100 / 110  or based on other conditions or parameters as will be described in more detail later. As such, the devices  100 / 110  do not always adhere to the same standard layer structures and protocols the entire time the connection is active. Instead, the host device  100  can flexibly modify or even replace some or all layer processing functions performed in support of the communication connection as operating conditions warrant. In some embodiments, the new or modified layer structure and protocol may not be in compliance with a communication standard any more, i.e. it may be a proprietary structure or protocol. For example, it could be determined that a configuration of a protocol may be more appropriate which is not in compliance with the communication standard for example by providing a data link layer which is not in compliance with data communication standards. For example, the modified layer structure or protocol could use all the functions specified in a communication standards but replace the error correction scheme by another type or another configuration of an error correction scheme when it is determined that the modified error correction scheme provides better transmission performance. 
     In one embodiment, the host device  100  determines an ad hoc communication layer structure and/or protocol for one or more communication layers  130  based on actual operating conditions. Each new layer processing function is ad hoc in that the function is not a standard function, but instead is tailored to the particular communication environment in which the host and requesting devices  100 / 110  are operating. For example, an ad hoc data link layer function enables data to be transferred between the host and requesting devices  100 ,  100  and may also enable the detection and possibly correction of errors that may occur in the physical layer. The host device  100 , requesting device  110  or other devices can measure the data rate, channel quality, BER (bit error rate) and/or other variables associated with the communication connection. This information can be used to determine whether a more optimal data link layer frame structure and/or protocol can be implemented instead of the standard data link layer structure and/or protocol used to initially establish the communication connection. According to one embodiment, a shorter frame size may be advantageous when BER is high or channel quality is poor. Alternatively or in addition, a more robust CRC (cyclic redundancy check) protocol or different type of error checking protocol may be preferred over the standard error checking protocol employed at the data link layer. 
     Other layers  130  of the communication standard can be analyzed for improvement based on operating conditions such as the type, quality and/or reliability of the application being executed by the devices. For example VoIP (Voice over IP) applications have a low delay tolerance and banking applications have high security requirements. These types of operating conditions as well as others can be considered when determining whether to modify or replace one or more of the standard layer structures and/or protocols implemented by the devices  100 / 110 . Replacing standard layer functions with more optimal layer functions can increase device performance, improve device reliability, reduce power consumption, etc. The decision to replace standard layer functions can also be based on the capabilities of the requesting device  110 , e.g., the bandwidth, memory size, processor speed and/or architecture, etc. of the requesting device  110 . 
     The host communication device  100  communicates the new layer information to the requesting device  1   10  for implementation. The requesting device  110  determines whether it can support the new layer structure and/or protocol and indicates this to the host device  100 . In response, the host device  100  replaces at least some of the standard layer processing functions implemented at the host device  100  with the new layer processing functions responsive to the requesting device  110  acknowledging acceptance of the new layer information. The devices  100 / 110  continue communication using the new layer structure(s) and/or protocol(s), optimizing device performance in view of actual operating conditions. The decision to replace or modify one or more layers  130  of a communication standard can be made during a setup or initialization period while the communication connection is being established or shortly thereafter. The decision to modify or replace one or more layer functions can be occasionally revisited while the connection remains active to account for changing operating conditions, e.g., changing BER, data rate, channel quality, etc. The operating conditions measured to make layer processing decisions can be associated with any layer of the communication standard, e.g., ranging from the physical layer to the application layer for the OSI model. 
     Certain communication standards such as DSL permit relatively direct device communication in a secure network environment. Other communication standards such as Ethernet, WLAN, etc. use intermediary network nodes  140  to facilitate a connection between the host communication and requesting devices  100 / 110 . These intermediary nodes  140  implement standard layer processing functions to initially establish the connection. As such, the host device  100  also communicates any new layer information to the intermediary nodes  140  that support the connection. According to one embodiment, one or more standard layer processing functions are replaced at the host device  100  responsive to the requesting device  110  and each intermediary node  140  acknowledging acceptance of new layer processing information. This ensures a reliable communication path is maintained over the entire physical connection, including at the intermediary nodes  140 . 
     In some embodiments, the intermediary nodes  140  do not implement the entire layer stack implemented by the host and requesting devices  100 / 110 . The intermediary nodes  140  do not always have to process data at the upper layers of the communication standard. In one embodiment, one or more of the intermediary nodes  140  are LAN (local area network) devices that operate at the physical and data link layers of the communication model and define communication over the various LAN media. In another embodiment, one or more of the intermediary nodes  140  are WAN (wide area network) devices that operate at the lowest three layers of the communication model and define communication over various wide-area media. In yet another embodiment, one or more of the intermediary nodes  140  are a routing device responsible for exchanging information between routers so that the routers can select the proper path for network traffic. 
     In more detail, each communication device  100 / 110  and intermediary node  140  (if present) has one or more programmable protocol processors  150 / 160 / 170  for implementing the different layers  130  of a communication standard. The protocol processors  150 / 160 / 170  are programmable so that the devices  100 / 110  and intermediary nodes  140  can implement layer processing functions in a soft, flexible manner based on actual operating conditions while maintaining reliable communication. This way, inflexible and rigid standard layer processing functions can be readily modified or replaced altogether with more optimal functions when operating conditions warrant. The programmable protocol processors  150 / 160 / 170  can be any type of logic device capable of executing code designed to implement layer processing functions. The programmable processors  150 / 160 / 170  may comprise a microprocessor, digital signal processor, programmable logic or any other type of programmable device. The programmable protocol processors  150 / 160 / 170  can be implemented in hardware, software, firmware or any combination thereof. 
     In one embodiment, each communication device  100 / 110  and intermediary node  140  (if present) has at least one programmable protocol processor  150 / 160 / 170  for implementing the functions associated with the physical and data link layers of a communication standard. Another protocol processor can be provided to implement the functions associated with the network layer of the communication standard. Other protocol processor configurations are possible depending on the application(s) under consideration and the communication standard(s) supported. The protocol processors  150 / 160 / 170  can also support multiple communication standards if desired, e.g., WiFi and WLAN, WLAN and 3GPP, etc. thereby enabling both wired and wireless communication at the devices  100 / 110 . In each case, the programmable protocol processors  150 / 160 / 170  implement standard layer structures and protocols to establish an initial connection between the host and requesting communication devices  100 / 110 . One or more of the standard layer structures and/or protocols can be modified or replaced by one or more ad hoc layer structures and/or protocols after the connection is established based on operating conditions. The standard layer structures and/or protocols can also be modified or replaced by newer standardized layer structures and/or protocols unavailable when the devices  100 / 110  were designed and manufactured such as successors of certain protocols. Accordingly, newer standardized communication protocol layers can be implemented as standards evolve without redesigning the devices  100 / 110 . 
       FIG. 2  illustrates an embodiment of central office (CO) equipment  200  communicatively coupled to a modem  210  over a DSL (digital subscriber line) communication network  220 . DSL is a family of technologies that provides digital data transmission over the wires of a local telephone network. DSL standards determine how information moves from a software application in the DSL modem  210  through the network medium to a software application in the CO equipment  200 . The CO equipment  200  and DSL modem  210  both have at least one programmable protocol processor  230 / 240  for implementing standard DSL layer processing so that a connection can be established between the devices  200 / 210 . According to one embodiment, the programmable protocol processors  230 / 240  have the added flexibility to modify or replace at least some of the standard DSL data link layer  232 / 242  functions implemented at the devices  200 / 210  with new ad hoc data link structure(s) and/or protocol(s) based on actual operating conditions. The new ad hoc data link layer functions enable data to be transferred between devices  200 / 210  and may also enable the detection and possibly correction of errors that may occur in the physical layer. In other embodiments, the programmable protocol processors  230 / 240  also have the added flexibility to modify or replace standard DSL layer functions implemented above and/or below the data link layer  232 / 242 , e.g., at the physical layer  250 / 260  or at layers  270 / 280  above the data link layer. 
     In one embodiment, some or all of the data link functionality of the standard DSL data link layer  232 / 242  can be modified or replaced by the programmable processors  230 / 240  as indicated by the dashed lines. Data link performance is affected by channel conditions and data loss. Accordingly, different standard CRC schemes are typically provided to address a range of conditions. Also, different standard frame sizes are also typically available to address a range of channel conditions and data loss scenarios. For example, longer frame sizes are permitted when channel conditions are good and BER is low. Conversely, shorter frame sizes are used when channel conditions are bad and BER is high. The programmable protocol processors  230 / 240  can modify the frame size (structure) and/or CRC algorithm (protocol) beyond the standardized boundaries, providing additional flexibility to the devices  200 / 210  to further improve performance based on channel conditions and/or BER. The programmable protocol processors  230 / 240  may even implement a different error detection algorithm other than CRC. Also, error checking and other protocols tend to be typically implemented at multiple layers of a communication standard. Too much redundancy of this kind can degrade performance. The programmable protocol processors  230 / 240  can reduce unnecessary redundancy by lowering the amount of error detection and/or other functions performed at different layers so that these functions are performed only at a few layers or a single layer depending on operating conditions and device requirements. This added flexibility permits the devices  200 / 210  to implement ad hoc layer processing functions tailored to the communication environment in which the devices  200 / 210  operate or newer standardized functions previously unavailable to the devices  200 / 210 . While the above is directed to the data link level, it is to be noted that other embodiments may provide the same described operations and flexibility for other layers for example PHY layer or specific sublayers, for example higher sublayers of the PHY layer, etc. 
       FIG. 3  illustrates an embodiment of a radio base station  300  communicatively coupled to user equipment  310  such as a mobile handset over a wireless UMTS Terrestrial Radio Access Network (UTRAN)  320 . UTRAN is part of the 3GPP family of wireless communication standards and can carry many traffic types from real-time circuit-switched data to IP-based packet-switched data. The base station  300  and user equipment  310  each implement various radio protocols such as MAC (media access control), radio link control (RLC), packet data convergence (PDC), broadcast/multicast control (BMC) and radio resource control (RRC) so that the devices  300 / 310  can communicate over the UTRAN wireless network  320 . The programmable processor  330  included in the base station  300  implements standard radio functions such as buffering, segmentation and concatenation, RLC header processing and ciphering. The programmable processor  340  included in the user equipment  310  implements corresponding standard radio functions such as de-ciphering, buffering, RLC header processing and reassembly. Standard radio functions such as these and others enable the devices  300 / 310  to establish an initial communication connection over the UTRAN wireless network. 
     The programmable protocol processors  330 / 340  have the added flexibility to modify or replace at least some of the standard radio layer functions with one or more ad hoc or newer standardized radio structures and/or protocols. The programmable protocol processors  330 / 340  may also have the added flexibility to modify or replace at least some of the standard layer functions implemented above and/or below the radio layer, e.g., at the physical layer  350 / 360  or at layers  370 / 380  above the radio layer. According to one embodiment, operating conditions such as channel conditions, BER and/or data rate determine whether any of the standard radio functions are replaced or modified with ad hoc structures and/or protocols. For example, an ad hoc packet compression algorithm may be implemented. Ad hoc retransmission and/or an ad hoc reordering algorithm can also be implemented, e.g., based on the availability of base station resources and/or transmission link quality. Redundancy can be eliminated from the different radio functions when conditions permit, e.g., by implementing ciphering at the MAC or RLC sub-layer, but not both as is standard practice. In addition, preexisting standard layer functions can be replaced with newer standardized functions as communication standards evolve. In each of these layer modification/replacement embodiments, the programmable protocol processors  330 / 340  implement the new layer functions to ensure reliable and stable communication. 
       FIG. 4  illustrates an embodiment of programmable processors included in the host and requesting devices  100 / 110 . Each programmable processor  400 / 410  includes a controller  402 / 412  for managing overall operation and transmit/receive circuitry  404 / 414  for implementing physical signaling. Each programmable processor  400 / 410  also includes a protocol engine  406 / 416  implemented in hardware, software, firmware or some combination thereof. The protocol engines  406 / 416 , e.g., a java engine or the like implement standard communication layer functions to establish an initial communication connection between the devices  100 / 110 . The protocol engines  406 / 416  also modify or replace some or all of the standard layer functions with new functions based on operating conditions as explained above. The process to determine whether to modify or replace a layer function can rest with the host protocol engine  406 , host controller  402  or other logic included in or associated with the host device  100  or can be made externally to the host device  100 , e.g., by a remote software program. In each case, the host protocol engine  406  has enough flexibility to implement new layer functions. 
     In one embodiment, new layer functions are described using an executable description of the new functions. As used herein, the term ‘executable description’ can be code ready for execution (e.g., executable code), code that requires a final compilation or interpretation step before execution (e.g., bytecode), markup language code such as HTML, XML, etc. or any other representation that can be processed to implement one or more new communication layer functions by the programmable processors  400 / 410 . In one embodiment, the protocol engines  406 / 416  execute the executable description to implement new layer functions. The code can be used natively on the devices  100 / 110  or interpreted without modification. Alternatively, the code is taken as a specification which is transformed (i.e., translated) to an equivalent code executable on each computing platform. 
     In one embodiment, the executable code is independent of the platform or operating system used by the devices  100 / 110 . In one embodiment, the code is a program running on each of a plurality of supported hardware/operating system platforms. In other words, according to embodiments, the program once written, is allowed to run everywhere either by compiling the written code before or by directly executing the written program. Thus, the program may be executed on every device  100 / 110  independent of the hardware and operating system used by the device  100 / 110 . In one embodiment, the executable code may run on a virtual machine such as a virtual Java machine. Thus, according to this embodiment, a virtual machine program such as a Java virtual machine program runs on the processor of devices  100 / 110  to make the device independent on the specific operating system and hardware. The virtual machine program running on the processor is capable to interpret the executable code. Thus, the executable code in this embodiment is not a machine code but is a virtual machine code such as a Java byte code similar to machine code, but intended to be interpreted by the virtual machine. The virtual machine may use standardized libraries. In one embodiment, the machine code generated by the virtual machine based on the virtual machine code or machine codes of frequently used parts of the program may be cached or stored and may be used in further sessions to run the program or parts of the program without the additional overhead of a virtual machine directly as native executables. 
     Furthermore, while the whole data processing of at least the data link layer based on the executable code may be performed in embodiments in software, other embodiments may have a combination of hardware and software. Thus, in these embodiments, hardware components which are beyond the hardware for a general purpose processor or a dedicated processor (such as a digital signal processor) may be provided in addition to the processor to perform processing which is basic to data communication protocol in hardware. Such processing may include fundamental parsing functions or parts thereof, fundamental security functions or parts thereof, fundamental error protection functions or parts thereof. Since only basic processing of the protocol is realized in hardware, the data processing based on the executable description is still flexible and changeable. 
       FIG. 5  illustrates an embodiment of a method for generating an executable description of a communication layer function, communicating the executable description to the requesting device  110  and executing the description at the host and requesting devices  100 / 110  to implement the new layer functions. For illustrative purposes only,  FIG. 5  shows how an executable description of a new data link structure and/or protocol is generated, communicated and executed. However, the executable description can be for any layer of a communication standard. 
     After an initial connection is established between the communication devices  100 / 110  (Step  1 ), the quality of the connection is assessed (Step  2 ), e.g., by gathering BER, channel quality, data rate and/or other information relating to the connection. As shown in  FIG. 4 , the information can be gathered by the host device  100  or by the requesting device  110  and fed back to the host device  100  over the connection. The host controller  402  and/or protocol engine  406  analyzes the connection information to determine whether any data link layer functions can be modified or replaced with more optimal functions (Step  3 ). If so, the host controller  402  and/or protocol engine  406  composes an executable description of a new data link layer frame structure and/or protocol as previously described herein (Step  4 ). Alternatively, the executable description can be composed external to the host device  100  and downloaded to the host  100  for execution (Step  4 ). In either case, the host device  100  communicates the executable description to the requesting device  110  using the standard data link layer structure and protocol (Step  5 ). In one embodiment, the executable description is communicated to the requesting device over a data channel of the communication connection. In another embodiment, a control signaling channel  420  of the connection is used to transmit the executable description to the requesting device  110  in accordance with the standard data link structures and protocols. 
     In either case, the requesting device  110  receives and extracts the executable description (Step  6 ). The requesting device controller  412  and/or protocol engine  416  determines whether the executable description is error-free and whether the protocol engine can implement the new data link layer frame structure and/or protocol represented by the executable description. In one embodiment, the requesting device controller  412  and/or protocol engine  416  compiles, interprets and/or executes the executable description to make this determination, depending on the type of executable description (e.g., executable code is executed, bytecode is compiled and/or interpreted during or before execution, etc.). The new data link layer frame structure and/or protocol is implemented at the requesting device if supported and error-free (Step  7 ). The requesting device  110  sends a message to the host device  100  indicating whether the new data link layer frame structure and/or protocol has been successfully implemented at the requesting device  110  (Step  8 ). If not acknowledged (NACK) by the requesting device  110 , the devices  100 / 110  continue communicating using the standard layer functions. If acknowledged (ACK) by the requesting device  110 , the host device  100  implements the new data link layer frame structure and/or protocol by compiling, interpreting and/or executing the executable description (Step  9 ). The host device  100  may send an optional acknowledgement message (ACK) to the requesting device  110  indicating the new data link layer function(s) have been implemented at the host device  100  (Step  10 ). Alternatively, no acknowledgement message (ACK) is sent to the requesting device  110 . In either embodiment, the requesting device  110  also implements the new data link layer frame structure and/or protocol by executing the executable description (Step  11 ). Accordingly, both devices  100 / 110  implement the new layer function(s) and begin communicating in accordance with these function(s) over the preexisting connection (Step  12 ). Otherwise, the devices  100 / 110  continue communicating using the standard functions. 
       FIG. 6  illustrates another embodiment of programmable processors  600 / 610  included in the host and requesting devices  100 / 110 . Each programmable processor  600 / 610  has a controller  602 / 612 , transmit/receive circuitry  604 / 614  and protocol engine  606 / 616  as described above. According to this embodiment, the protocol engines  606 / 616  access respective protocol selection logic  620 / 630  such as a lookup table to identify which of one or more predetermined ad hoc layer structures and/or protocols should be implemented by the communication devices  100 / 110 . The protocol selection logic  620 / 630  stores or has access to a plurality of predetermined ad hoc layer structures and/or protocols. If one or more of the predetermined structures and/or protocols is determined to be more optimal than a standard structure and/or protocol, the standard structure and/or protocol is replaced by the more optimal solution. The requesting device  110  can be notified of which predetermined ad hoc layer structure(s) and/or protocol(s) to implement by sending an index or other type of identifier to the requesting device  110 . In one embodiment, the index/identifier is communicated to the requesting device  110  over a data path of the communication connection. In another embodiment, the index/identifier is communicated to the requesting device  110  over a control signaling channel  640  of the communication connection. In either case, the index/identifier determines which ad hoc layer structure(s) and/or protocol(s) should be chosen by the requesting device selection logic  630  and implemented by the requesting device protocol engine  616 . 
     With the above range of variations and applications in mind, it should be understood that the present invention is not limited by the foregoing description, nor is it limited by the accompanying drawings. Instead, the present invention is limited only by the following claims and their legal equivalents.