Abstract:
A method and apparatus of providing a piggybacked positive acknowledgement/negative acknowledgement (ACK/NACK) (PAN) field indicator (PANI) and a polling indicator are disclosed. A combined field of a PANI bit, a relative reserved block period (RRBP) bit and an EGPRS supplementary polling (ES/P) field may indicate a polling scheme and a presence of a PAN field. Alternatively, the presence of the PAN field in the data block may be indicated by using a specific training sequence. Alternatively, a forward error correction (FEC) coding may be performed on the data block including the header, and the presence of the PAN field may be indicated by scrambling the encoded bits corresponding the header with a specific scrambling sequence. Alternatively, a header check sequence (HCS) may be generated and the presence of the PAN field is indicated by mixing a predetermined sequence with the HCS.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. provisional application No. 60/916,691 filed May 8, 2007, which is incorporated by reference as if fully set forth. 
     
    
     FIELD OF INVENTION 
       [0002]    This application is related to wireless communications. 
       BACKGROUND 
       [0003]    Latency reduction is one of the considerations in a GSM/EDGE radio access network (GERAN). Two techniques have been proposed for the latency reduction: reduced transmission time interval (RTTI) and fast acknowledgement/non-acknowledgement (ACK/NACK) reporting (FANR). 
         [0004]    Under current GERAN protocols, the network may obtain feedback data, (i.e., ACK/NACK of downlink data packets), from the mobile station through polling. The polling is indicated by an evolved general packet radio service (EGPRS) supplementary polling (ES/P) field. Two (2) ES/P bits indicate whether a relative reserved block period (RRBP) field is valid or not and what fields the next uplink control block shall contain. 
         [0005]      FIGS. 1-3  show conventional EGPRS downlink radio link control/medium access control (RLC/MAC) header types 1, 2, and 3, respectively. Both the ES/P field and the RRBP field are present in all three RLC/MAC header types. Table 1 shows the meaning of the conventional 2-bit ES/P field. 
         [0000]    
       
         
               
               
             
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 bits 
                   
               
             
          
           
               
                 5 
                 4 
                 ES/P 
               
               
                   
               
               
                 0 
                 0 
                 RRBP field is not valid (no Polling) 
               
               
                 0 
                 1 
                 RRBP field is valid - Extended Ack/Nack bitmap type 
               
               
                   
                   
                 FPB 
               
               
                 1 
                 0 
                 RRBP field is valid - Piggy-backed Ack/Nack bitmap type 
               
               
                   
                   
                 FPB 
               
               
                 1 
                 1 
                 RRBP field is valid - Extended Ack/Nack bitmap type 
               
               
                   
                   
                 NPB, measurement report included 
               
               
                   
               
             
          
         
       
     
         [0006]    Conventionally, an ACK/NACK report is sent in an explicit message, also referred to as an RLC/MAC control block. The ACK/NACK report is addressed to a particular radio resource, called a Temporary Block Flow (TBF). A TBF is a temporal connection between a mobile station and a network to support a uni-directional transfer of data. A TBF is temporary and is maintained only for the duration of the data transfer. 
         [0007]    It has been proposed that the ACK/NACK feedback for a certain TBF be “piggybacked” on an RLC/MAC data block that may be addressed to another TBF. The field that carries this ACK/NACK feedback is referred to as “piggybacked ACK/NACK (PAN) field”. The presence or absence of the PAN field in the RLC/MAC data block is indicated by a PAN indicator (PANI). 
         [0008]    In order to send the PANI, an extra bit may be included in a downlink data packet header as shown in  FIGS. 1-3 . However, currently there is no available space in the downlink data packet header. It has been proposed to split the conventional 2-bit RRBP field such that one bit is used for the RRBP field and the other bit is used for the PANI. Tables 2 and 3 show the meaning of the 1-bit RRBP field and 1-bit PANI field. 
         [0000]    
       
         
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                 Bit 
                 Full-rate PDCH uplink block with TDMA frame number 
               
               
                   
               
             
             
               
                 0 
                 (N + 8 or N + 9) mod 2715648 
               
               
                 1 
                 (N + 13) mod 2715648 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
               
             
           
               
                 TABLE 3 
               
               
                   
               
               
                 bit 
                 PANI 
               
               
                   
               
             
             
               
                 0 
                 A PAN field is not included 
               
               
                 1 
                 A PAN field is included 
               
               
                   
               
             
          
         
       
     
         [0009]    In accordance with this proposal, the header size remains the same. However, there is redundancy in bit combinations. If the ES/P bits are “00”, (i.e., when there is no polling request), the combinations of the RRBP bit and the PANI bit include wastage of three (3) combinations. Therefore, it would be desirable to provide a scheme for more efficient signaling of a PANI, an RRBP, and a polling indicator. 
       SUMMARY 
       [0010]    A method and apparatus of providing a PANI and a polling indicator are disclosed. A combined field of a PANI bit, an RRBP bit, and an ES/P field may indicate a polling scheme and a presence of a PAN field. Alternatively, the presence of the PAN field in the data block may be indicated by using a specific training sequence. Alternatively, a forward error correction (FEC) coding may be performed on the data block including the header, and the presence of the PAN field may be indicated by scrambling the encoded bits corresponding the header with a specific scrambling sequence. Alternatively, a header check sequence (HCS) may be generated and the presence of the PAN field is indicated by mixing a predetermined sequence with the HCS. Block sequence number 2 (BSN2) bits may be used to indicate the existence of a PAN field. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings wherein: 
           [0012]      FIGS. 1-3  show conventional EGPRS downlink RLC/MAC header types 1, 2, and 3, respectively; 
           [0013]      FIG. 4  is a block diagram of a base station in accordance with the third embodiment; 
           [0014]      FIG. 5  is a block diagram of a WTRU in accordance with the third embodiment; 
           [0015]      FIG. 6  is a block diagram of a base station in accordance with the fourth embodiment; and 
           [0016]      FIG. 7  is a block diagram of a WTRU in accordance with the fourth embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    When referred to hereafter, the terminology “wireless transmit/receive unit (WTRU)” includes but is not limited to a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a pager, a cellular telephone, a personal digital assistant (PDA), a computer, or any other type of user device capable of operating in a wireless environment. When referred to hereafter, the terminology “base station” includes but is not limited to a Node-B, a site controller, an access point (AP), or any other type of interfacing device capable of operating in a wireless environment. 
         [0018]    In accordance with a first embodiment, a 1-bit PANI field, a 1-bit RRBP field, and a 2-bit ES/P field in an RLC/MAC header are combined together to indicate a polling scheme and an existence of a PAN field in the data block. The bit combinations of the PANI field, the RRBP field and the ES/P field do not have any redundancy. Example PANI, RRBP and ES/P bit combinations and their meaning are shown in Table 4. 
         [0019]    In Table 4, the first bit, read from left, is a PANI field, the second bit is an RRBP field, and the third and fourth bits are an ES/P field. When the first bit, (i.e., the PANI field), is set to ‘1’, it indicates that a PAN field is included in the data block, and if the first bit is set to ‘0’, it indicates that a PAN field is not included in the data block. It should be noted that the bit combinations in Table 4 are provided as an example, not as a limitation, and any other combination may be used and any other meaning may be associated with the bit combinations. 
         [0000]    
       
         
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 4 
               
               
                   
               
               
                 PANI + 
                   
               
               
                 RRBP + ES/P 
                 Meaning 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 0 
                 0 
                 0 
                 0 
                 No Polling; No PAN 
               
               
                 0 
                 1 
                 0 
                 0 
                 Polling (FPB bitmap; N + M); No PAN 
               
               
                 1 
                 0 
                 0 
                 0 
                 Polling (FPB bitmap as UL-PAN; N + M); PAN 
               
               
                 1 
                 1 
                 0 
                 0 
                 No Polling; PAN 
               
               
                 0 
                 0 
                 0 
                 1 
                 Polling (FPB bitmap; N + 8 or N + 9); No PAN 
               
               
                 0 
                 1 
                 0 
                 1 
                 Polling (FPB bitmap; N + 13); No PAN 
               
               
                 1 
                 0 
                 0 
                 1 
                 Polling (FPB bitmap; N + 8 or N + 9); PAN 
               
               
                 1 
                 1 
                 0 
                 1 
                 Polling (FPB bitmap; N + 13); PAN 
               
               
                 0 
                 0 
                 1 
                 0 
                 Polling (FPB bitmap as UL-PAN; N + 8 or N + 9); 
               
               
                   
                   
                   
                   
                 No PAN 
               
               
                 0 
                 1 
                 1 
                 0 
                 Polling (FPB bitmap as UL-PAN; N + 13); No PAN 
               
               
                 1 
                 0 
                 1 
                 0 
                 Polling (FPB bitmap as UL-PAN; N + 8 or N + 9); 
               
               
                   
                   
                   
                   
                 PAN 
               
               
                 1 
                 1 
                 1 
                 0 
                 Polling (FPB bitmap as UL-PAN; N + 13); PAN 
               
               
                 0 
                 0 
                 1 
                 1 
                 Polling (CQR - NPB bitmap; N + 8 or N + 9); No 
               
               
                   
                   
                   
                   
                 PAN 
               
               
                 0 
                 1 
                 1 
                 1 
                 Polling (CQR - NPB bitmap; N + 13); No PAN 
               
               
                 1 
                 0 
                 1 
                 1 
                 Polling (CQR - NPB bitmap; N + 8 or N + 9); PAN 
               
               
                 1 
                 1 
                 1 
                 1 
                 Polling (CQR - NPB bitmap; N + 13); PAN 
               
               
                   
               
             
          
         
       
     
         [0020]    For example, the bit combinations 0100 and 1000 may be used to specify additional polling schemes, (e.g., those eliminated in reducing the conventional RRBP bits from 2 to 1), or to demand reporting of channel quality report (CQR) or next partial bitmap (NPB) when there is not enough space to send both. The parameter M may be chosen suitably. 
         [0021]    In accordance with a second embodiment, a training sequence is used to indicate the presence of the PAN field in the RLC/MAC data block. Under the current GERAN specification, one of eight (8) training sequences is used for communication between a WTRU and a network in a cell. In accordance with the second embodiment, eight (8) training sequence groups are defined with each group having two (2) training sequences. One training sequence is used in a cell for all communications between the WTRU and the network and the presence of a PAN field in the RLC/MAC data block is indicated by using the other training sequence in that training sequence group. 
         [0022]    In accordance with a third embodiment, a scrambling code is used to indicate the presence of the PAN field in the RLC/MAC data block.  FIG. 4  is a block diagram of a base station  400  in accordance with the third embodiment. The base station  400  includes a data block processing entity  402 , an encoder  404 , a scrambler  406 , and a transceiver  408 . The data block processing entity  402  generates a data block including a header. The header includes the ES/P field and the RRBP field. The encoder  404  performs an FEC coding on the data block including the header. If the data block does not include a PAN field, the data block is transmitted by the transceiver  408  as in the prior art. If the data block includes a PAN field, the scrambler  406  scrambles the encoded bits corresponding to the header with a scrambling sequence and the data block including the scrambled bits are transmitted by the transceiver  408 . 
         [0023]    For scrambling, the encoded bits are modulo-2 added to a pre-specified scrambling sequence. The length of the scrambling sequence may be same to that of the encoded bits corresponding to the header. The scrambling sequence is unique and known to both the base station and the WTRU. The scrambling code may be generated in a number of ways, or selected in accordance with criterion that the distance between the scrambling code and the all “zero” sequence is maximized. 
         [0024]      FIG. 5  is a block diagram of a WTRU  500  in accordance with the third embodiment. The WTRU  500  includes a transceiver  502 , a decoder  504 , a descrambler  506 , and a controller  508 . The transceiver  502  receives a bit sequence of a data block from the base station  400 . The decoder  504  performs FEC decoding on the received bit sequence as in the prior art. If the data block does not include a PAN field and therefore the bits corresponding to the header was not scrambled at the base station  400 , the decoder  504  may succeed in decoding. However, if the data block includes a PAN field and therefore the bits corresponding to the header was scrambled at the base station  400 , the received bit sequence will be rejected due to having too many bit errors. If the received bit sequence is rejected, the received bits corresponding to the header are descrambled, (i.e., moculo-2 added with the scrambling sequence), by the descrambler  506 . The received bit sequence with the descrambled header portion of the bit sequence is then decoded again by the decoder  504 . If the second FEC decoding is successful, the controller  508  detects that a PAN field is included in the data block. 
         [0025]    In accordance with a fourth embodiment, a modified HCS is used to indicate the presence of the PAN field. A radio block for data transfer includes one RLC/MAC header, an HCS, one or more RLC data block(s), and a block check sequence (BCS). The data block may include a PAN field and an optional PAC check sequence (PCS). The HCS is used for error detection of the RLC/MAC header. The HCS may be eight bits long. 
         [0026]      FIG. 6  is a block diagram of a base station  600  in accordance with the fourth embodiment. The base station  600  includes a data block processing entity  602 , a HCS encoder  604 , a modulo-2 adder  606 , and a transceiver  608 . The data block processing unit  602  generates a data block including a header. The header includes an ES/P field and an RRBP field. The HCS encoder  604  generates an HCS. If the radio block does not include a PAN field, the radio block is transmitted by the transceiver  608  as in the prior art. If the radio block includes a PAN field, the modulo-2 adder  606  adds a predetermined sequence to the HCS, and the radio block with the modified HCS is transmitted by the transceiver  608 . For example, a sequence 11111111 may be used as the predetermined sequence. In this case, the HCS bits are inverted. 
         [0027]      FIG. 7  is a block diagram of a WTRU  700  in accordance with the fourth embodiment. The WTRU  700  includes a transceiver  702 , an HCS decoder  704 , a modulo-2 adder  706 , and a controller  708 . The transceiver  702  receives a data block from the base station  600 . The HCS decoder  704  performing HCS decoding with the received header of the data block and the received HCS. If the header is received error free, (i.e., the HCS check passes), the controller  708  may assume that no PAN is present in the RLC/MAC data block. If the HCS check fails, the received header is modulo-2 added with the predetermined sequence by the modulo-2 adder  706 , and HCS check is performed again. If the second HSC check passes, the controller  708  may assume that the header is correct and the PAN field is included in the RLC/MAC data block. 
         [0028]    In accordance with a fifth embodiment, the existence of a PAN field may be signaled using block sequence numbers (BSNs). Currently, the header includes an 11 bit BSN1 and a 10 bit BSN2. Once the BSN1 is specified, BSN2 is forced to be within a certain vicinity of BSN1. The vicinity is specified by a window size (WS). Conventionally, a WS of 10 bits is adequate. In accordance with the fifth embodiment, the current WS is halved so that only 9 bits are needed to signal BSN2. The unused tenth BSN2 bit in the header may be used to indicate a PANI. 
         [0029]    Although features and elements are described above in particular combinations, each feature or element can be used alone without the other features and elements or in various combinations with or without other features and elements. The methods or flow charts provided herein may be implemented in a computer program, software, or firmware incorporated in a computer-readable storage medium for execution by a general purpose computer or a processor. Examples of computer-readable storage mediums include a read only memory (ROM), a random access memory (RAM), a register, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks, and digital versatile disks (DVDs). 
         [0030]    Suitable processors include, by way of example, a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, any other type of integrated circuit (IC), and/or a state machine. 
         [0031]    A processor in association with software may be used to implement a radio frequency transceiver for use in a wireless transmit receive unit (WTRU), user equipment (UE), terminal, base station, radio network controller (RNC), or any host computer. The WTRU may be used in conjunction with modules, implemented in hardware and/or software, such as a camera, a video camera module, a videophone, a speakerphone, a vibration device, a speaker, a microphone, a television transceiver, a hands free headset, a keyboard, a Bluetooth® module, a frequency modulated (FM) radio unit, a liquid crystal display (LCD) display unit, an organic light-emitting diode (OLED) display unit, a digital music player, a media player, a video game player module, an Internet browser, and/or any wireless local area network (WLAN) or Ultra Wide Band (UWB) module.