Abstract:
Flexibly configurable layer one transport channels produce radio blocks in response to communication information and extract communication information from radio blocks. One of the transport channels can be enabled to extract its associated communication information from a radio block while another of the transport channels is maintained disabled. The one transport channel provides the extracted communication information to a decision maker in a higher layer. In response to the extracted communication information, the decision maker decides whether the other transport channel should be enabled, and provides to the physical layer an indication of its decision.

Description:
This application claims the priority under 35 USC 119(e)(1) of copending U.S. provisional application No. 60/287,401, filed on May 1, 2001 and incorporated herein by reference. 

   FIELD OF THE INVENTION 
   The invention relates generally to the radio interface to a PLMN and, more particularly, to layer one of the radio interface and its interaction with higher layers. 
   BACKGROUND OF THE INVENTION 
     FIG. 1  diagrammatically illustrates a conventional example of a PLMN coupled to a mobile station (MS)  13  via a physical radio interface  17 . The PLMN includes a radio access network  11  coupled to a core network  15 . The core network  15  can be either a packet switched core network or a circuit switched core network. The mobile station  13  (any type of mobile radio transceiver) communicates with a base transceiver station (BTS) of the radio access network  11  via the radio interface  17 . The physical layer, also referred to as layer one or the PHY layer, of the mobile station  13  (and the physical layer of the corresponding BTS of the radio access network  11 ) is responsible for transmission of data over the radio interface  17 . On the transmitter side, layer one (L 1 ) performs tasks including channel coding (error detecting and error correcting), interleaving, burst formatting, modulation and radio transmission. On the receiver side, layer one performs tasks including radio reception, synchronization, channel estimation, demodulation (equalization), de-interleaving and channel decoding (error correction and error detection). 
   Examples of the core network  15  include circuit switched or packet switched GSM, and circuit switched or packet switched UMTS. The radio access network  11  can be, for example, the GSM/EDGE radio access network (GERAN). 
   The PLMN of  FIG. 1  is capable of providing a variety of services to its end users, each service having its own specific requirements regarding error rates, delay, etc. In order to accommodate the required services, the core network  15  requests from the radio access network  11  bearer services that transport information between the mobile station  13  and the edge of the core network  15 . If the core network is a third generation (3G) core network, for example a UMTS network, the bearers (which provide the bearer services) are referred to as radio access bearers or RABs. A request for an RAB from a 3G core network to the radio access network  11  is specified by a set of RAB parameters. The RAB parameters contain a description of the information to be transferred, together with requirements on bit error rates, block error rates, delay, etc. 
   The RAB request contains information about the service to be supported by the call that is being set up, for example maximum bit rate, guaranteed bit rate, maximum payload size, maximum error rate, etc. The information in such an RAB request is typically independent of the type of radio access network  11 . For example, the RAB request looks the same whether the radio access network  11  is GERAN or UTRAN. 
   In conventional radio access networks such as GERAN or UTRAN, layer one of the radio interface provides transport channels which either transport information from higher layers to the actual physical radio channel(s), or which transport information received from the actual physical radio channel(s) to the higher layers. Conventionally, these layer one (L 1 ) transport channels are divided into two main types, optimized and generic. 
   With the optimized approach, the layer one transport channels are set up based on exact knowledge of the transported information blocks for a particular service. This permits, for example, voice to be transported efficiently over the radio interface. The speech frames can be unequally protected (UEP) and, just as important, unequal error detection (UED) can be used. 
   In the generic approach, the layer one transport channels are set up without detailed knowledge of the service. Generic transport channels use equal error protection and detection. Padding and segmentation can be used to handle variations in the payload size. 
   The optimized approach provides good spectrum efficiency for speech, for example AMR (adaptive multi-rate), but the optimized channel approach disadvantageously requires specific channels to be defined for each service. On the other hand, although generic transport channels are more flexible, they disadvantageously lead to poor radio interface performance for certain services, for example speech services. 
   Conventional layer one transport channels are static in the following aspects: the number of information bits to transfer per radio block is fixed; the error detection scheme for each part of the information block is fixed; the error correction scheme (including code type and rate) for each part of the information block is fixed; the puncturing pattern is fixed; and the interleaving is fixed. 
   There are a number of conventional predefined layer one transport channel schemes, for example optimized schemes that have been developed for AMR, and generic schemes such as GPRS, EGPRS and ECSD. According to conventional operation, higher layers choose a set of these predefined schemes depending on the service that is being supported. 
   As indicated above, the layer one transport channels generally interface between higher layers and the physical radio channel(s). For example, GERAN provides for radio transport via physical subchannels, where each physical subchannel is a sequence of GSM time slots that are allocated for the particular data transfer. A physical subchannel can be either a full-rate (FR) channel or a half-rate (HR) channel. A set of consecutive GSM time slots on a physical subchannel, used for the transfer of one block of data received from (or bound for) one or more layer one transport channels, is called a radio block. In some conventional systems, for example those that utilize GPRS and EGPRS, a radio block consists of four GSM time slots. 
   One or more types of modulation can be available for use on a given physical radio channel. For example, one or both of GMSK modulation and 8-PSK modulation can be used on the aforementioned GERAN physical subchannels. 
   It can therefore be seen that the actual gross data rate available for a data transfer depends on the data rate associated with the physical radio channel and the modulation used on the physical radio channel. In the GERAN example, the data rate available for data transfer depends on whether the physical subchannel is full-rate or half-rate, and also depends on whether the modulation is GMSK, 8-PSK, or a combination thereof. 
   Some examples of conventional layer one transport channel schemes for services defined in GERAN are described below. 
   The layer one transport channel schemes for AMR are examples of optimized schemes, i.e., they are tailor made to give the best possible performance for a particular speech codec. To provide transport of AMR speech over the radio interface, a number of layer one transport channel schemes are defined. There are currently eight different speech codec modes defined for AMR. For each of these eight modes, a layer one transport channel scheme for transport over a full-rate physical subchannel with GMSK modulation is defined. Further, for six of the modes, layer one transport channel schemes are defined for transport with GMSK on a half-rate physical subchannel. 
   The speech information is delivered to layer one in blocks (also denoted as speech frames) the size of which depends on the AMR mode. One speech frame is delivered every 20 ms. Below follows a description of exemplary layer one transport channel processing for the AMR  12 . 2  mode for transport over a GMSK FR channel. 
   The speech frame delivered from the speech codec consists of 244 speech bits and two inband bits (used for signalling). Of the speech bits, 81 are more important for the speech quality, and therefore more sensitive to errors (called class 1A bits). The remaining 163 bits are less sensitive (called class 1B bits). The speech bits are sorted by layer one according to their importance, putting the class 1A bits first and the class 1B bits after. Six CRC bits are added after the 81 class 1A bits, giving 87 bits. The class 1B bits are put after the CRC bits. All these bits are then encoded together using a convolutional coder with rate R=1/2. This results in an encoded block of 508 bits. Sixty encoded bits in the latter part of the encoded block (corresponding to the class 1B bits) are punctured (i.e., not transmitted). Effectively, this increases the code rate of the class 1B bits, giving them less protection. This results in a block of 448 bits. The 2 inband bits are encoded to 8 bits using a block code. The encoded inband bits are put together with the encoded speech bits, giving a block of 456 bits. Finally, the 456 bits are diagonally interleaved over 8 half bursts and transmitted over the radio interface. 
   For each of the other AMR modes, similar layer one transport channel schemes are defined. A particularity of the layer one transport channel schemes for AMR is that different parts of the information are given different degrees of protection against errors. Further, one part is protected with error detecting codes, while other parts are not. This unequal treatment of different parts is referred to as unequal error protection (UEP). The layer one transport channel scheme for each mode is very specific for that mode, and can not be used for any other mode, and definitely not for other services. 
   The layer one transport channel schemes of EGPRS are examples of generic schemes. They are not optimized for a particular service. The packets of data to be transferred can have any size. The packet is segmented by the RLC/MAC layer into RLC data blocks of a size that fits the layer one transport channel schemes. On the receiving side, the packet is reassembled from the received RLC data blocks. 
   The layer one transport channel schemes of EGPRS do not treat any particular part of the RLC data block differently. However, the RLC/MAC layer adds an RLC/MAC header to each RLC data block, which is given more protection than the RLC data block. In some sense, the EGPRS layer one transport schemes are optimized, since they require a specific RLC/MAC header size and a specific RLC data block size. However, they are not optimized for a certain type of user data (i.e., they do not assume any particular size or structure of the data packet before segmentation). 
   In EGPRS, nine different layer one transport channel schemes are defined, called MCS- 1  to MCS- 9  (Modulation and Coding Scheme). Each has a different RLC data block size. MCS- 1  to MCS- 4  uses GMSK modulation, while MCS- 5  to MCS- 9  uses 8-PSK modulation. In GERAN, only FR physical subchannels can be used. The nine schemes have different degrees of error protection. In each radio block the scheme is chosen based on the channel quality, to maximize the throughput. 
   Below follows a description of an MCS- 6  example. 
   To layer one a block having a total of 622 bits is delivered. The first 28 bits are the RLC/MAC header, of which the first three bits define a field called USF. The remaining 594 bits are the RLC data block. The USF field is encoded with a block code to 36 bits. To the 25 remaining RLC/MAC header bits, an eight bit CRC is added, giving 33 bits. These are then encoded with a tail-biting convolutional code with rate R=1/3. Finally, one spare bit is added, giving a block of 100 bits. The encoded RLC/MAC header is interleaved. To the 594 bits of the RLC data block a 12-bit CRC is added, giving 612 bits. These are encoded with a convolutional code with rate 1/3, and punctured. The puncturing is evenly distributed throughout the block, giving equal protection to all bits. After puncturing, the block has 1248 bits. The encoded RLC data block is also interleaved. Finally, the encoded USF, RLC/MAC header and RLC data block are put in a radio block and transmitted. 
   New services are continuously being introduced in the PLMN, and radio access networks such as GERAN are expected to provide bearers capable of handling these services. For example, the following new services have been discussed in the GERAN standardization: adaptive multi-rate wideband speech (AMR WB); and voice over IP services. 
   Further, it is desirable to be able to transport the information of such new services over different types of physical channels (e.g. FR and HR) and with different modulations (e.g. GMSK and 8-PSK) Another desirable improvement is to be able to transport old services over new physical channels or with new modulations. For example, AMR narrowband (NB) with 8-PSK over a half-rate physical subchannel has been discussed. For each combination of service, physical channel and modulation, new layer one transport channel schemes are needed. 
   Some drawbacks associated with the current way of specifying layer one transport channels in GERAN are discussed below: 
   New circuit switched voice services have been introduced in GERAN. The Narrowband AMR is being designed for HR 8-PSK channels. The new speech codec wideband AMR is also being introduced, both for FR GMSK and FR 8-PSK. These new codecs require at least 8 rates per physical subchannel (FR, HR, etc). Each rate needs to have its own convolutional coding and puncturing table in memory. At the same time, each channel coding rate has to have performance requirements for 22 different propagation conditions specified in 45.005. After implementation of the new channel coding in the product, everything needs to be tested and verified. 
   For voice over IP, when adding an IP header to the voice frames, it is no longer possible to use the existing optimized voice bearers defined for GSM since the payload format changes. If IP header compression is used, the size of the compressed header will vary over time. A new layer one transport channel scheme is needed for each speech codec mode/IP header size combination to transport the IP header together with the speech. Therefore “Optimized VoIP” has been discussed in GERAN standardization, where the basic idea is to remove the IP header. By doing so, it is possible to use standard AMR optimized channel coding. Some disadvantages with the current solution are absence of IP transparency, handover between cells with different AMR capability, and a different solution compared to UTRAN (the VoIP application will be RAN dependent). 
   The IP Multimedia Subsystem is being defined in 3GPP for REL-5. One example is unequal error protection on packet switched conversational multimedia services where several subflows (bit classes) will be transported down to the physical layer. This enables robust header compression (ROHC) to be used in combination with UEP/UED. Currently, GERAN can not use the same solutions developed for UTRAN. 
   Additional services can be expected in the future, for instance new streaming services for video applications. Also for these, new layer one transport channel schemes are needed. 
   Thus, the traditional way of using predefined and fixed layer one transport channel schemes disadvantageously implies memory-consuming and complex implementations at the physical layer, as well as costly changes in order to be able to provide new services. New layer one transport channel schemes are needed for each new service and for each new physical channel on which a service must be transported. 
   The invention advantageously provides flexibly configurable layer one transport channels for producing radio blocks in response to communication information and for extracting communication information from radio blocks. According to some exemplary embodiments, each transport channel includes an encoder or a decoder coupled to and cooperable with a data puncturer or a data repeater. According to some exemplary embodiments, an information source produces for each transport channel first configuration information and second configuration information, wherein the first configuration information is indicative of how the associated transport channel is to be configured if a first modulation type is used for a current radio block, and wherein the second configuration information is indicative of how the associated transport channel is to be configured if a second modulation type is used for the current radio block. According to some exemplary embodiments, the physical layer includes a description information source that provides description information from which various configurations of the transport channels can be determined. The description information source provides the description information in the physical layer in response to further information which the description information source receives from a higher layer and which is indicative of a service request initiated by a communication network. According to some exemplary embodiments, one of the transport channels is enabled to extract its associated communication information from a radio block while another of the transport channels is maintained disabled. The one transport channel provides the extracted communication information to a decision maker in a higher layer. In response to the extracted communication information, the decision maker decides whether the other transport channel should be enabled, and provides to the physical layer an indication of its decision. The other transport channel can then be enabled if the decision maker provides an enable indication. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  diagrammatically illustrates a mobile station in radio communication with a PLMN according to the prior art. 
       FIG. 2  diagrammatically illustrates pertinent portions of exemplary embodiments of a radio transceiver that supports communication across the radio interface of  FIG. 1 . 
       FIG. 3  diagrammatically illustrates the layer one transport channels of  FIG. 2  in greater detail. 
       FIG. 4  illustrates the format of an exemplary radio block according to the invention. 
       FIG. 5  illustrates the response of the present invention to an RAB request from a core network. 
       FIGS. 6 and 6A  illustrate information elements included within exemplary Transport Format Combination Set descriptors according to the invention. 
       FIG. 7  illustrates in tabular format exemplary CRC types which can be represented by the value of a corresponding field in  FIG. 6 . 
       FIG. 8  illustrates in tabular format exemplary error correction code types which can be represented by the value of a corresponding field in  FIG. 6 . 
       FIG. 9  illustrates in tabular format radio block sizes which can be represented by the value of a corresponding field in  FIG. 6 . 
       FIG. 10  illustrates in tabular format radio block interleave types which can be represented by the value of a corresponding field in  FIG. 6 . 
       FIG. 11  diagrammatically illustrates examples of the layer one transport channels of  FIGS. 2 and 3 . 
       FIG. 12  illustrates an exemplary Transport Format descriptor that can be used to selectively limit the layer one processing of incoming radio blocks according to the invention. 
       FIG. 13  conceptually illustrates exemplary operations which can be performed according to the invention in response to the Transport Format descriptor of  FIG. 12 . 
       FIG. 14  conceptually illustrates further exemplary operations which can be performed in response to the Transport Format descriptor of  FIG. 12 . 
       FIG. 15  diagrammatically illustrates pertinent portions of exemplary embodiments of a radio transceiver which can perform the operations illustrated in either or both of  FIGS. 13 and 14 . 
       FIG. 16  diagrammatically illustrates pertinent portions of further exemplary embodiments of a radio transceiver according to the invention. 
   

   DETAILED DESCRIPTION 
   The present invention permits customized and/or optimized layer one transport channels to be configured while a given call is being set up. These layer one transport channels can be configured, for example, in a manner that will best support the service associated with the call. 
     FIG. 2  diagrammatically illustrates pertinent portions of exemplary embodiments of a radio transceiver according to the invention, for example a radio transceiver within a mobile station of the type generally shown at  13  in  FIG. 1 , or a radio transceiver within a base transceiver station (BTS) of the type generally shown in  FIG. 1 . The transceiver portion illustrated in  FIG. 2  resides generally in layer one (the physical, or PHY, layer) of the transceiver. A plurality of layer one transport channels (L 1  TCs) at  12  communicate data bits bidirectionally with layer two (L 2 ) at  201 . The layer one transport channels at  12  also communicate radio blocks bidirectionally with a radio block interleaver/de-interleaver  25  at a radio block port  200 . The radio block interleaver/de-interleaver  25  is in turn coupled for bidirectional communication with physical radio channels (e.g., GERAN physical subchannels). Of course, a modulator/demodulator is interposed between the radio block interleaver/de-interleaver and the physical channels. This structure, which is well known in the art and not necessary to understand the invention, is not explicitly shown in  FIG. 2 . 
   The layer one transport channels are configured in accordance with configuration information designated herein as transport formats (TFs). Each layer one transport channel is configured according to a respective transport format. A group of transport formats that define the layer one transport channels for a given call are referred to herein as a transport format combination (TFC). A plurality of transport format combinations can be stored in a TFC storage device  14 , and the constituent transport formats of a selected transport format combination are output at  26  from the storage device  14  in order to configure the transport channels  12  for transmission or reception of a given radio block at radio block port  200 . For radio block reception, the layer one transport channels at  12  are configured by their respective transport formats to produce data bits at  201  in response to the received radio block at  200 , which data bits are forwarded to layer two. In transmission operations, the layer one transport channels  12  are configured by their respective transport formats to produce an outgoing radio block at  200  in response to data bits received at  201  from layer two. 
   The transport format combinations are produced by a transport format assembler  16  and then stored at  14 . The transport format assembler  16  assembles each individual transport format of every transport format combination in response to information received from a decoder  18 , and also in response to information modules stored in an information module storage device  20 . Each information module stored at  20  contains information which can be used to configure a layer one transport channel to perform a desired function, for example CRC coding, error correction coding, code puncturing, code repetition, and interleaving. In response to control information received from the decoder  18 , the transport format assembler  16  retrieves selected information modules from the storage device  20  and assembles those modules together to produce a transport format which will be used to configure an associated layer one transport channel at  12 . For example, a transport format for transmitting may include information modules respectively corresponding to CRC coding, error correction coding and code puncturing. An exemplary transport format for receiving may include information modules respectively corresponding to de-interleaving, error correction decoding and CRC decoding. The information module storage device  20  can include, for example, information modules respectively corresponding to a plurality of CRC coding/decoding schemes, and information modules respectively corresponding to a plurality of different error correction coding/decoding schemes. 
   Thus, the transport format assembler  16  is capable of assembling many different transport formats that respectively correspond to different possible combinations of the information modules stored at  20 . As mentioned above, the assembler  16  also groups individual transport formats together into transport format combinations which are stored at  14 . Each transport format combination can be used to configure a plurality of layer one transport channels at  12 , each transport channel configured by a respectively corresponding transport format of the transport format combination. 
   The decoder  18  provides the control information to the transport format assembler  16  in response to a transport format combination set (TFCS) descriptor stored at  21 . The TFCS descriptor is received from a control plane layer of the transceiver. The TFCS descriptor is provided on a per call basis, so each TFCS descriptor is associated with a corresponding call identifier (call ID), also provided from the control plane layer at  27 . The TFCS descriptor for a given call contains all information needed by the transport format assembler  16  to assemble a set of all transport format combinations which will be available for use during the associated call. The TFCS descriptor includes the information needed by the transport format assembler  16  to group the various transport formats into the appropriate transport format combinations for storage at  14 . The transport format combinations are applied to configure the layer one transport channels  12  on a per radio block basis. More specifically, for each incoming or outgoing radio block, a new transport format combination can be selected from the storage device  14  for appropriate configuration of the layer one transport channels. The layer one transport channels at  12  then either produce the radio block at  200  from the data bits at  201 , or produce the data bits at  201  from the radio block at  200 . 
   The transport format combination storage device at  14  can include transport format combination sets respectively corresponding to a plurality of different TFCS descriptors that respectively correspond to a plurality of different calls. The TFCS descriptors are provided during call set up, along with the call identification information at  27 . The TFCS descriptors are stored at  21  (indexed, e.g. by the associated call IDs), and are available to the decoder  18 . The decoder  18  decodes each TFCS descriptor and provides to the transport format assembler  16  all information needed to assemble the transport format combination set associated with the TFCS descriptor. The assembler  16  can assign transport format combination indicators (TFCIs) which uniquely identify the respective transport format combinations of the set specified by a given TFCS descriptor. The transport format assembler  16  can use the TFCI to index each of the transport format combinations in the storage device  14 , and the call ID can be used to index the desired transport format combination set in device  14 . The assembler  16  can assign TFCI values, for example, in the order in which it produces and stores the TFCs of the TFCS. In some embodiments, TFCI for a given TFCS can have values from “1” through the total number of TFCs in the TFCS. 
   During transmissions, layer two provides the TFCI to layer one in order to specify which transport format combination is desired for the current radio block of the current call. A TX/RX signal  28 , indicative of whether transmission or reception operations are occurring, controls a selector  22  so that the TFCI is provided to the storage device  14  directly from layer two during transmission operations. The transport format combination storage device  14  also receives the call ID  27  and the TX/RX signal. The call ID permits the storage device to determine which set of transport format combinations stored therein is to be accessed, TFCI indicates which transport format combination within that set is to be used, and the TX/RX signal indicates whether to use a receiving version of the selected transport format combination or a transmitting version of the selected transport format combination. The receiving version configures the layer one transport channels at  12  to receive radio blocks at  200  and produce therefrom data bits at  201 , and the transmit version of the transport format combination configures the transport channels at  12  to receive data bits at  201  and produce therefrom a radio block at  200 . 
   Also during transmissions, TFCI as received from layer two is passed through selector  23  for input to an associated one of the layer one transport channels  12 . TFCI is processed by the associated layer one transport channel for inclusion in the radio block at  200 . Each TFCS descriptor includes information which defines a transport format that will be used to configure a layer one transport channel for the TFCI, in order to permit the TFCI to be transmitted in the radio block to the receiving end. The transport format corresponding to TFCI is provided at  26  to the associated layer one transport channel. Also provided at  26  are the transport formats for one or more data channels corresponding to the data bits at  201 . Each outgoing radio block is thus produced by passing the data bits at  201  and the TFCI through appropriate layer one transport channels at  12  to produce the radio block at  200 . 
   During reception, the TFCI is received within the radio block  200 , and passes through its associated layer one transport channel to storage device  14  via selector  22  (by virtue of the TX/RX signal indicating receive operation). Thus, the received TFCI can be applied to the storage device  14  in order to identify the transport format combination that is to be used to process the rest of the incoming radio block. The transport formats of the selected transport format combination are then applied to the corresponding layer one transport channels at  12 , thereby permitting the remainder of the layer one transport channels to process the remainder of the radio block at  200  in order to produce the data bits at  201 . 
   A receive (Rx) controller  24  can be utilized to control when the layer one transport channels are enabled during receive operation. The receive (Rx) enables produced by the receive controller  24  ensure that only the layer one transport channel associated with TFCI is enabled at first, and the receive controller  24  thereafter enables the remainder of the layer one transport channels, after the received TFCI has been used to obtain the desired transport format combination from the storage device  14 . 
     FIG. 3  diagrammatically illustrates the layer one transport channels of  FIG. 2  in more detail.  FIG. 3  illustrates the layer one transport channels individually, with their respective transport formats and receive enable signals. As shown, the layer one transport channel for TFCI receives the corresponding TFCI transport format, designated as TF(TFCI). The layer one transport channel for TFCI, designated L 1 TC(TFCI) in  FIG. 3 , also receives a corresponding receive enable signal from the receive controller  24 . This receive enable signal is designated EN(TFCI) in  FIG. 3 .  FIG. 3  also illustrates an exemplary transport format combination, namely the nth transport format combination, designated as TFC(n). As shown in  FIG. 3 , TFC(n) includes N n  transport formats, designated in  FIG. 3  as TF( 1 ) . . . TF(N n ). Thus, the nth transport format combination includes N n  transport formats, which in turn configure N n  corresponding layer one transport channels, designated L 1 TC( 1 ) . . . L 1 TC(N n ) in  FIG. 3 . Each of the N n  channels also receives a corresponding receive enable signal, designated as EN( 1 ) . . . EN(N n ) in  FIG. 3 . For an exemplary transport format combination set having M transport format combinations, the index n in  FIG. 3  can take values of 1, 2, . . . M. Also, each of the M transport format combinations can include its own uniquely associated number of transport formats, designated as N n  in  FIG. 3 . 
   During transmission, the layer one transport channels of  FIGS. 2 and 3  collectively output a radio block at  200  and, during reception, the layer one transport channels collectively receive a radio block at  200  as input.  FIG. 4  illustrates an example of a radio block that can be collectively output by the layer one transport channels, or can be received collectively as an input by the layer one transport channels. As shown in  FIG. 4 , the radio block includes a TFCI portion (e.g., a layer one header) which indicates the transport format combination that has been used at the transmitter and should therefore be used at the receiver also. The remainder of the radio block carries user data. The radio block illustrated in  FIG. 4  corresponds to a value of n=M in  FIG. 3 , so the radio block includes N M  user data portions (corresponding to N M  L 1 TCs) in addition to the TFCI information portion. The portion of radio block  41  designated Transport Format  1  is the portion of the radio block that has been produced by L 1 TC( 1 ) (transmit operation) or the portion of the radio block that is to be input to L 1 TC( 1 ) (receive operation). Similarly, the portion of radio block  41  designated Transport Format N M  represents the output of L 1 TC(N M ) (transmit operation) or the input to L 1 TC(N M ) (receive operation). 
   Because one or more of the layer one transport channels can be configured differently from all other layer one transport channels, and thus may have, for example, a different propagation delay than all other layer one transport channels, a multiplexing apparatus or other suitable parallel concatenating apparatus (not explicitly shown in  FIGS. 2 and 3 ) can be coupled to the radio block side of the layer one transport channels to concatenate the outputs of the individual layer one transport channels together in order to format the radio block generally as shown in  FIG. 4 . The radio block formed in this manner can then be input to the radio block interleaver at  25 . From the point where the radio block is input to the interleaver  25 , the radio block can be subjected to generally conventional interleaving, modulating and any other suitable conventional processing (not explicitly shown) before transmission on the physical radio channel(s). 
   As mentioned above, when a call for a desired service is being set up, a 3G core network in a conventional PLMN transmits to the radio access network of the PLMN an RAB request that contains information about the service for which the call is being set up. In the example of a GERAN radio access network, the radio resource control (RRC or RR) layer of GERAN can be configured according to the invention to translate the RAB request into a corresponding TFCS descriptor (see also  FIG. 2 ) for the call. The RRC (or RR) layer can perform this translation based on the above-described information provided in the RAB request, together with other information that is conventionally available in the radio access network, for example available radio resources, etc. The RRC (or RR) layer can be designed according to the invention to find a suitable configuration (specified by a TFCS descriptor) of layer one transport channels to fulfill the requirements in the RAB request, and at the same time economize with respect to resource utilization in the radio access network. The RRC (or RR) layer in GERAN (for example in a BTS of GERAN) can send the TFCS descriptor to the physical layer of GERAN, and can also send the TFCS descriptor to the RRC (or RR) layer of the mobile station. The RRC (or RR) layer of the mobile station can, according to the invention, forward the TFCS descriptor to layer one of the mobile station. The above-described exemplary handling of an RAB request is illustrated in  FIG. 5 . The example of  FIG. 5  uses the RRC layer. In  FIG. 5 , layer one of the BTS and layer one of the mobile station are designated as the PHY layer. 
     FIG. 6  illustrates an exemplary TFCS descriptor according to the invention. As indicated above, the TFCS descriptor includes all of the information that the transport format assembler  16  needs to assemble from the information modules stored at  20  all transport formats of each transport format combination that will be available for the call to which the TFCS descriptor corresponds. As shown in  FIG. 6 , the TFCS descriptor includes a field which specifies the size of the radio block (see also  200  in  FIG. 2 and 41  in  FIG. 4 ), a field which specifies the number of TFCs available for use during the call, and a field which specifies the type of interleaving/de-interleaving that will be implemented by the radio block interleaver/de-interleaver at  25  in  FIG. 2 . The TFCS descriptor of  FIG. 6  also includes a TFCI descriptor  62 . This TFCI descriptor includes a data structure  62 A having a field which specifies the number of bits which are to be output by the L 1 TC(TCFI) during transmission (the number of input bits for L 1 TC(TFCI) during transmission is implicitly known from knowing the number TFCs), a field which specifies the type of CRC coding/decoding that will be applied in L 1 TC(TFCI), a field which specifies the type of error correction coding/decoding that will be implemented in L 1 TC(TFCI) and, in the embodiment of  FIG. 6 , a 1 bit field which indicates whether or not interleaving is to be used within L 1 TC(TFCI). During reception, the output bits field of course specifies the number of bits that will be input to L 1 TC(TFCI). In some embodiments, L 1 TC(TFCI) is configured to provide better performance than the most robust of L 1 TC( 1 ) . . . L 1 TC(N M ). 
   The TFCS descriptor of  FIG. 6  also includes a transport format combination (TFC) descriptor  63  which specifies the number of TFCs available for the call, and which further includes a TFC descriptor data structure for each TFC associated with the TFCS. An example of such a TFC descriptor data structure is shown at  63 A. 
   Each TFC descriptor data structure includes a field which specifies the number of transport formats in that TFC, and also includes a transport format descriptor  64  that specifies, for each transport format of the TFC, a transport format descriptor data structure. An example of such a transport format descriptor data structure is shown at  64 A. As shown in  FIG. 6 , an exemplary transport format descriptor data structure includes a plurality of fields which include information to be used by the transport format assembler  16  of  FIG. 2  in assembling from the information modules at  20  the transport format that will be used to configure a corresponding layer one transport channel at  12 . The transport format descriptor data structure example shown at  64 A in  FIG. 6  includes an 11 bit field for specifying the number of bits that will be input to the corresponding transport channel (for example during transmit), another 11 bit field for specifying the number of bits that will be output from the corresponding transport channel (again, for example, during transmit), a 3 bit field for specifying the type of CRC coding/decoding that will be used in the corresponding transport channel, another 3 bit field for specifying the type of error correction coding/decoding that will be used in the corresponding transport channel and, in the embodiment of  FIG. 6 , a 1 bit field for specifying whether or not the corresponding transport channel will apply interleaving/deinterleaving. If the “bits in” field and “bits out” field are defined for transmit operation, then they can simply be swapped with one another for receive operation. 
   The decoder  18  of  FIG. 2  can extract from the TFCS descriptor (for example the TFCS descriptor of  FIG. 6 ) all information needed by the transport format assembler  16  to produce the transport format combinations stored at  14 .  FIG. 7  illustrates in tabular format exemplary types of CRC coding/decoding which can be designated by corresponding CRC field values in the TFCS descriptor. The information needed to implement the various illustrated exemplary types of CRC coding/decoding can be contained in corresponding information modules stored at  20  in  FIG. 2 . Similarly,  FIG. 8  illustrates in tabular format exemplary types of error correction coding/decoding which can be designated by the corresponding field values in the TFCS descriptor. Again, all information needed to implement the various exemplary types of error correction coding/decoding shown in  FIG. 8  can be contained in corresponding information modules stored at  20  in  FIG. 2 . 
     FIG. 9  illustrates in tabular format various exemplary radio block sizes which can be specified by the radio block size field value of the TFCS descriptor. As illustrated in  FIG. 9 , different possible combinations of modulation and physical channel data rates have associated therewith different radio block sizes. 
     FIG. 10  illustrates in tabular format various exemplary types of radio block interleaving which can be specified by the corresponding field value in the TFCS descriptor. Although the radio block interleaving/de-interleaving at  25  in  FIG. 2  is not strictly a part of the layer one transport channels  12 , and is not defined by the transport formats illustrated in  FIG. 2 , nevertheless this information provided in the TFCS descriptor can be extracted by the decoder  18  and provided to the interleaver/de-interleaver  25  (not explicitly shown in  FIG. 2 ) to control the operation of the interleaver/de-interleaver  25 . 
   Regarding the use of code puncturing or code repetition, either may be needed in the transport channels in order to ensure that the number of bits output by the transport channel (during transmit or receive) matches the number of bits specified by the transport format descriptor data structure associated with that transport channel. Puncturing would be necessary if the transport channel would otherwise produce a number of output bits larger than that specified by the transport format descriptor data structure, and repetition would be necessary if the transport channel would otherwise output a number of bits smaller than the number of output bits specified by the transport format descriptor data structure. The need for puncturing (or repetition) can be determined by the transport format assembler  16  when assembling the transport format combinations for storage at  14 . If puncturing or repetition is used in a transport channel on the transmit side, then corresponding de-puncturing or de-repetition can be used in a corresponding transport channel on the receive side. 
   The puncturing (or repetition) pattern can be derived algorithmically based on the number of bits before and after puncturing (or repetition). The number of bits before puncturing (or repetition) is implicitly known (code rate*(information bits+CRC bits)). The number of bits after puncturing (or repetition) is a parameter (e.g., the “bits out” parameter of  FIG. 6 ). 
   For instance, the puncturing can be derived as follows: 
   If a block of N bits shall be punctured to contain M bits, the bits at positions
 
 J =floor( I*N /( N−M ))
 
   are punctured, where
 
 I= 0, . . .  N−M −1
 
   and “floor” means taking the integer part. 
   If, on the other hand, repetition shall be done, the repetition can be derived as follows: 
   If a block of N bits shall be repeated to contain O bits, the bits at positions
 
 J =floor( I*N /( O−N ))
 
   are repeated, where
 
 I= 0 , . . . , O−N −1
 
   and “floor” means taking the integer part. 
   If error correction is required, the channel (i.e., error correction) coding can be chosen from a set of available channel coding types (see, e.g.,  FIG. 8 ). This set can, for instance, include non-recursive terminated convolutional coding, recursive systematic terminated convolutional coding and tail-biting convolutional coding and block codes. The constraint length of the convolutional codes is a parameter (e.g.,  5  or  7  as shown in  FIG. 8 ). 
   The rate of the error correction code is implicitly defined by the number of inbits (information bits+CRC bits) and the number of outbits after puncturing; in some embodiments, the rate is chosen as the highest rate possible considering the required number of output bits after rate matching. If a code rate lower than e.g. 1/4 is needed, the rate 1/4 can be chosen and repetition can be used to lower the code rate. The constraint length and the rate implicitly define the polynomials of the error correction codes (fixed polynomial sets). In one example application of the invention, layer one can be configured to support AMR. Assuming narrowband AMR, there are 8 channel codecs conventionally available, each having a different amount of class 1A bits and class 1B bits per 20 ms speech frame. This example assumes that 4 of the 8 channel codecs are available, so four TFCs would be needed (one for each codec). According to some embodiments of the invention, the class 1A bits and class 1B bits and AMR signalling (inband) bits can be transported through respectively different layer one transport channels, so each TFC would specify three transport formats: one for class 1A bits; one for class 1B bits; and one for the inband bits. A given TFC can correspond, for example, to a conventional coding scheme such as CS-1, O-TCH/AHS122 or O-TCH/AHS795. Thus, the TFCS can be seen to support conventional link adaptation. 
   In addition to the speech frames, call control signalling (e.g., FACCH) and silence information descriptor (e.g., SID UPDATE) can be supported on the physical subchannel. This results in a total of 6 TFCs specified in the TFCS descriptor, namely, the 4 TFCs for the 4 available codecs, one TFC for the call control signalling, and one TFC for the silence information descriptor. 
     FIG. 11  conceptually illustrates exemplary operations according to the invention during transmission. As shown in  FIG. 11 , the TFCI passes through its corresponding layer one transport channel at  110 , and the data bits received from layer two pass through the layer one transport channels specified by a selected one of TFC( 1 ), TFC( 2 ), . . . , TFC(M) (see also  FIGS. 3 and 4  and discussion thereof above). As shown in  FIG. 11 , each TFC(n) for n=1. 2, . . . , M includes N n  transport formats which in turn specify N n  layer one transport channels. The outputs of the transport channels implemented by the selected transport format combination are concatenated together (e.g., by associated multiplexes), and the result is concatenated at  115  with the output of the TFCI layer one transport channel  110 , thereby producing a radio block (see also  FIG. 2 ) at  118  for radio block interleaving at  119 . Each layer one transport channel illustrated in the example of  FIG. 11  includes CRC coding, error correction coding, puncturing (or repetition), and interleaving. Corresponding transport channels at the receiver can include corresponding CRC decoding, error correction decoding, de-puncturing (or de-repetition), and de-interleaving. 
   In view of the fact that the TFCI is not actually user data, and can be transmitted as a layer one header as shown, for example, in  FIGS. 4 and 11 , the layer one processing of all TFCI does not strictly constitute a transport channel for user data. How, because the operations performed on TFCI in layer one are analogues to those performed on the user data in layer one, the layer one processing of TFCI is also referred to herein as a layer one transport channel, (see also L 1 TC (TFCI) of  FIG. 3 ). 
   The invention can also support the use of GMSK modulation and 8-PSK modulation on the same physical subchannel. One exemplary embodiment defines transport format combinations and corresponding transport format combination indicators for each type of modulation. Blind detection can then be performed at the receiving side on a per radio block basis before decoding the TFCI information. In order to limit the complexity, such multi-modulation support could be allowed, for example, only for block interleaved data.  FIG. 6A  illustrates an exemplary TFCS descriptor for such multi-modulation operation. 
   When a shared physical subchannel is used in the downlink (e.g., from  11  across  17  in  FIG. 1 ), all radio blocks on the channel are not necessarily intended for one MS. Instead, several MSs can listen to one physical subchannel. Based on information within each received block, each MS decides whether it is the intended recipient of the block. This is the situation, for example, in GPRS and EGPRS. Since the conventional layer one is aware of what each part of the block contains, layer one of each MS can decode only the parts of the block needed to decide if the block is intended for that MS. To achieve flexibility, the receiving layer one according to some embodiments of the invention is not aware of the contents of the radio block data—except for the L 1  header (containing the TFCI). In such embodiments, layer one only decodes the block and delivers it to layer two. This means decoding all blocks entirely. This has the drawback that processing power and battery power can be wasted on blocks not intended for the MS. 
   The situation can be even more severe when the MS has no ongoing downlink data flow, but only an uplink flow. In conventional GPRS and EGPRS, for example, a special part of the downlink radio blocks, called the uplink state flag (USF), tells the MS whether it is allowed to transmit in uplink or not. If there is no ongoing downlink flow, only the USF needs to be decoded. However, if all parts of the downlink block are decoded in layer one and delivered to higher layers in the MS, and if the higher layers then use only the USF, this causes unnecessary power consumption. 
   When conventional incremental redundancy is used, the physical layer (e.g., in EGPRS) needs to know the RLC sequence number of the received block(s) in order to perform soft combination of earlier transmissions of the same block. Conventionally, layer one extracts the RLC sequence number from the RLC/MAC header. This type of operation is problematic in inventive embodiments wherein layer one is unaware of the content of the received radio block. 
   Therefore, some embodiments of the invention delay the operation of selected L 1 TCs during reception. So, initially (after extracting TFCI), only a subset of the L 1 TCs operate to deliver information to higher layers. The higher layers then interpret the received information to decide what additional L 1 TCs should be enabled for operation. 
   To support this, a Send Up bit is included in the transport format descriptor. The Send Up bit indicates whether or not the L 1 TC should operate and send its output to a higher layer. Thus, the Send Up bit(s) of a TFC indicate whether all L 1 TCs should operate, or whether only a subset of all L 1 TCs should operate initially, pending a decoding order from a higher layer. The exemplary transport format descriptor structure of  FIG. 12  includes such a Send Up bit. In some embodiments, the Send Up bit can be stored by assembler  16  (of  FIG. 2 ) in TFC storage  14  along with the corresponding transport format. 
   For example, a scheme similar to EGPRS could be achieved if only the L 1 TCs that handle the RLC/MAC header and the USF are operated initially. Based on the result, higher layers can decide if the remaining L 1 TCs should be operated. 
     FIG. 13  illustrates exemplary operations which can be performed according to the invention in response to a Send Up bit such as shown in  FIG. 12 . At  131 , the received TFCI information is passed through its corresponding L 1 TC in order to determine which TFC is being used. All transport formats of the TFC are then inspected for active Send Up bits. In the example of  FIG. 13 , the transport formats associated with the RLC/MAC header and the USF include active Send Up bits, so the RLC/MAC header and the USF are passed through their corresponding L 1 TCs to higher layers. This is illustrated at  132  and  133  in  FIG. 13 . Based on the content of the RLC/MAC header (e.g. an address therein such as the temporary flow identifier TFI used in conventional GRRS/EGPRS), the RLC/MAC layer tells layer one whether or not to enable the L 1 TC associated with the RLC data block. In the example of  FIG. 13 , the L 1 TC for the RLC data block is enabled, as illustrated at  135 , and the RLC information produced by that L 1 TC is forwarded to the RLC/MAC layer at  136 . Also in  FIG. 13 , the RLC/MAC layer can determine from the USF information (forwarded at  132  and  133 ) whether or not transmission is permitted in the next uplink block. 
     FIG. 14  illustrates exemplary operations which can be performed in response to Send Up bits when incremental redundancy is supported. At  141 , L 1 TC(TFCI) is enabled so that the TFCI information can be examined to determine which TFC is being used. Also at  141 , the Send Up bit of each transport format of the selected TFC is inspected. In the example of  FIG. 14 , the transport format associated with the RLC/MAC header includes an active Send Up bit, so the corresponding L 1 TC is enabled at  142 , in order to permit the RLC/MAC header information to be forwarded to the RLC/MAC layer at  143 . At  144 , the RLC/MAC layer provides an RLC sequence number to layer one, together with an instruction to enable the L 1 TC associated with the RLC data block. At  145 , previously stored soft values of a previously received RLC data block having the same RLC sequence number are obtained and, at  146 , the presently received RLC data block (from the received radio block) is applied to its L 1 TC. The L 1 TC for the RLC data block uses the stored soft values retrieved at  145  and the present RLC data block (which also includes soft values) to decode the present RLC data block. At  147 , new soft values produced by operation of the L 1 TC (for example, due to incorrect CRC) are stored and, at  148 , if the CRC is correct, the RLC data produced by the L 1 TC is forwarded to the RLC/MAC layer. 
   Soft values are real numbers, indicating both the value (1 or 0) of a received bit, and the likelihood that the bit was correctly received. A positive sign of the soft value indicates a “0” while a negative value indicates a “1”. A large absolute value indicates a reliable bit, while a small absolute value indicates an unreliable bit. 
     FIG. 15  diagrammatically illustrates pertinent portions of exemplary transceiver embodiments that support the operations illustrated in  FIGS. 13 and 14 . When the TX/RX signal (see also  FIG. 2 ) indicates receive operation, a receive controller  151  uses the received TFCI information to determine from TFC storage  14  which transport formats of the selected TFC include an active Send Up bit. The receive controller  151  then enables the L 1 TCs corresponding to those transport formats which include active Send Up bits. Thereafter, the receive controller  151  receives information  152  from the RLC/MAC layer, which information indicates which (if any) additional L 1 TCs should be enabled such that the information associated therewith can be forwarded to the RLC/MAC layer. The receive controller  151  is responsive to this information  152  to enable the remaining L 1 TCs accordingly. The operations of  FIG. 14  can be supported by providing a soft values storage portion  153 . In response to information (e.g. an RLC sequence number) received at  152  from the RLC/MAC layer, the receive controller  151  can cause the soft values storage portion  153  to exchange soft values with a selected L 1 TC (as shown by broken lines in  FIG. 15 ), for example, the L 1 TC associated with the RLC data block of  FIG. 14 . 
   Referring again to  FIG. 1 , when GERAN, for example, is attached to a 2G core network, a specific service request is conventionally used instead of a generic RAB request. For example, Enhanced Full-Rate Speech can be requested in a conventional Assignment Request message from the 2G core network to GERAN. GERAN then conventionally selects a corresponding predefined coding scheme for that specific service. Unlike an RAB, the Assignment Request only signals a service, not the parameters associated with the service. Thus, the Assignment Request cannot be translated into a TFCS descriptor as in  FIG. 5 . 
   Some embodiments therefore store a preconfiguration for each service that is supported in the 2G core network. The preconfiguration contains all information necessary to configure the L 1 TCs for a service, for example, Wideband AMR, in terms of bit classes (transport formats), bits in/out, coding, etc. A preconfiguration table stored in the MS and in the radio access network, for example, in the BTS on the GERAN side, is used when the 2G core network sends an Assignment Request to set up the service. This advantageously permits the 2G core network to use its existing conventional signalling procedures. 
     FIG. 16  diagrammatically illustrates pertinent portions of exemplary embodiments of a transceiver according to the invention which can support a service request from a 2G core network. It is initially noted that the service request received by the radio access network (or suitable information representative of the service request) can be distributed to layer one of both the radio access network and the mobile station in generally the same fashion that the TFCS descriptor is distributed to layer one of both the radio access network and the mobile station using for example, the RRC or RR layer (see also  FIG. 5 ). As shown in  FIG. 16 , the service request, as received, in this example, from the RRC layer, is applied to a preconfiguration table  161  which is responsive to the service request to produce a TFCS descriptor which has been pre-selected for use with such a service request, and has been stored in table  161 . The table  161  can store therein a plurality of TFCS descriptors indexed against corresponding service requests. The selected TFCS descriptor can be transferred to the storage device  21  of  FIG. 2  and, from that point, the transceiver can operate, for example, generally as described above with respect to  FIGS. 2–15 . 
   It will be evident to workers in the art that the embodiments of  FIGS. 2–16  can be implemented, for example, by suitably modifying software, hardware or a combination of software and hardware, in conventional radio access networks and mobile stations. 
   Although exemplary embodiments of the invention are described above in detail, this does not limit the scope of the invention, which can be practiced in a variety of embodiments.