Abstract:
Methods and base stations are described. A base station includes a receiver, a processor and a transmitter. The receiver receives a first data block associated with an uplink temporary block flow (TBF), and the first data block includes a first header that includes a temporary flow identity (TFI) that identifies the uplink TBF. The processor generate a piggybacked acknowledgement/non-acknowledgement (PAN) field corresponding to the uplink TBF and a PAN check sequence (PCS) based on the PAN field, masks a subset of PCS bits with the TFI to generate a masked PCS, and generates a second data block, associated with a downlink TBF, that includes a second header, a data part corresponding to the downlink TBF, the PAN field, and the masked PCS. The transmitter transmits the second data block.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 13/406,121, filed Feb. 27, 2012, which is a continuation of U.S. patent application Ser. No. 12/056,433 filed Mar. 27, 2008, which issued as U.S. Pat. No. 8,126,013 on Feb. 28, 2012, which claims the benefit of U.S. Provisional Application Nos. 60/908,535 filed Mar. 28, 2007, 60/945,057 filed Jun. 19, 2007, 60/944,982 filed Jun. 19, 2007, 60/945,034 filed Jun. 19, 2007, and 60/956,765 filed Aug. 20, 2007, all of which are incorporated by reference as if fully set forth herein. 
     
    
     FIELD OF INVENTION 
       [0002]    The present invention is related to a wireless communication system. 
       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]    Conventionally, an ACK/NACK report is sent in an explicit message, also referred to as a radio link control/medium access control (RLC/MAC) control block. The ACK/NACK report is addressed to a particular radio resource, called a Temporary Block Flow (TBF). 
         [0005]    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. Each TBF is assigned a temporary flow identity (TFI) by the network. The TFI is unique among concurrent TBFs in each direction and is used instead of mobile station identity in the RLC/MAC layer. The same TFI is included in every RLC header belonging to a particular TBF. 
         [0006]    It has been proposed to send the ACK/NACK report for a certain TBF as a “piggyback” on an RLC/MAC data block that may be addressed to another TBF. The field that carries the ACK/NACK report is referred to as a piggybacked ACK/NACK (PAN) field. 
         [0007]    Since the PAN field is included in a data block that may be addressed to a different TBF, it is necessary to identify to which TBF the PAN field is addressed. Various proposals have been made to identify the correct TBF in the PAN field, including using a TFI or an uplink (UL) state flag (USF). During establishment of the uplink TBF, a USF is assigned to each mobile station. The USF is used by the network to indicate which mobile terminal is allowed to transmit in the following uplink radio block. 
         [0008]    In either case, some number of bits, (typically ranging from three to five), should be dedicated to the TBF identity in the PAN field. It would be desirable to have an efficient method of sending the TBF identity in the PAN field such that no dedicated bits are needed to identify the TBF. 
       SUMMARY 
       [0009]    A method and apparatus are described for indicating a TBF to which a PAN field is addressed. A PAN check sequence (PCS) is created, for example using a cyclic redundancy check (CRC) encoding. The PCS is masked with a TFI assigned to a TBF or a mask generated based on the TFI. A data block including the PAN field and the masked PCS is then processed for transmission. The mask may be generated by converting the TFI using an (M, N) code, M being the number of bits of the PCS and N being the number of bits of the TFI. With this scheme, a TFI may be transmitted in a PAN field without using explicit bits to identify the TBF. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings wherein: 
           [0011]      FIG. 1  shows an example radio block; 
           [0012]      FIG. 2  is an example block diagram of a transmitting station; and 
           [0013]      FIG. 3  is an example block diagram of a receiving station. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    When referred to hereafter, the terminology “wireless transmit/receive unit (WTRU)” includes but is not limited to a user equipment (UE), a mobile station (MS), 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. 
         [0015]      FIG. 1  shows an example radio block  100 . The radio block  100  for data transfer includes one RLC/MAC header  102 , a header check sequence (HCS)  104 , one or more RLC data block(s)  106 , a block check sequence (BCS)  108 , a PAN field  110 , and a PCS  112 . The RLC/MAC header  102 , the RLC data block(s)  106  and the PAN field  110  are coded separately for error detection and correction, and a separate checksum, (e.g., a cyclic redundancy check (CRC) checksum), is attached to each of them. The RLC/MAC header  102  contains a control field indicating whether a PAN field  110  is included or not in the radio block  100 . The HCS  104  is used for error detection of the RLC/MAC header  102 . The BCS  108  is used for error detection of the RLC data block  106 . A separate BCS may be included for each RLC data block. The PAN field  110  contains piggy-backed ACK/NACK information sent in one direction to provide acknowledgement for a TBF in the other direction. The PCS  112  is used for error detection of the PAN field  110 . 
         [0016]      FIG. 2  is an example block diagram of a transmitting station  200 . The transmitting station  200  may be a WTRU, a Node-B, or any other apparatus or device. The transmitting station  200  includes an encoder  202 , a masking unit  204 , and a transceiver  206 . A PAN field is input into the encoder  202 . The encoder  202  generates a PCS based on the PAN field  201 . For example, the encoder may be a cyclic redundancy check (CRC) encoder and the PCS may be a CRC checksum generated based on the PAN field  110 . The masking unit  204  then masks the PCS with a TFI, (i.e., TFI is used as a mask). The masking of the PCS bits with the TFI may be performed by modulo-2 addition, (i.e., an exclusive OR (XOR) operation). The transceiver  206  sends a data block  100  including the PAN field  110  and the masked PCS  112 . With this scheme, a TFI may be transmitted in a PAN field without using explicit bits to identify the TBF. Before transmission, a channel coding, (such as forward error correction (FEC) coding, rate matching, interleaving, or the like), may be performed. 
         [0017]    At least one bit of the TFI is masked with at least one bit of the PCS. For example, when the number of PCS bits (M) is greater than the number of TFI bits (N), (e.g., N=5 and M=10), the TFI bits may be mapped to a portion or all of the PCS bits, (e.g., first N bits, last N bits, or a subset of the M bits). The opposite case is also possible if N is greater than M. 
         [0018]    Alternatively, the transmitting station  200  may include a mask generator  208 . The mask generator  208  generates a mask from the TFI, and the masking unit  204  masks the PCS with the mask generated by the mask generator  208 . The N-bit TFI may be converted into an M-bit mask using an (M, N) code, (M is the number of bits of the PCS), and then the mask may be XORed with the PCS. 
         [0019]    Alternatively, the N-bit TFI may be converted into an L-bit mask using an (L, N) code, where L&lt;M, (M is the number of bits of the PCS), and then the mask may be XORed with the PCS. For example, when the number of PCS bits (M) is greater than the number of mask bits (L), (e.g., L=8 and M=10), the mask bits may be mapped to a portion or all of the PCS bits, (e.g., first L bits, last L bits, or a subset of the L bits). The opposite case is also possible. 
         [0020]    The M-bit mask may be selected to provide improved separation, (e.g., Hamming distance), between the M bit sequences. For example, it may be obtained by binary multiplying the N-bit TFI with a generator matrix. A good masking code shall have the largest possible minimum distance and the lowest frequency of occurrence of this minimum value. 
         [0021]    Example generator matrices of the linear binary codes with maximal minimum distances are provided below. In these examples, the TFI is assumed to be 5 bits long. 
         [0022]    (1) A (6,5) code with minimum distance 2 (applicable if M=6): 
         [0000]    
       
         
           
             
               
                 
                   1 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
               
               
                 
                   0 
                 
                 
                   1 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
               
               
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
               
               
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   0 
                 
                 
                   1 
                 
               
               
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   1 
                 
               
             
             . 
           
         
       
     
         [0023]    (2) A (7,5) code with minimum distance 2 (applicable if M=7): 
         [0000]    
       
         
           
             
               
                 
                   1 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   1 
                 
               
               
                 
                   0 
                 
                 
                   1 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   1 
                 
               
               
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   1 
                 
               
               
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   1 
                 
               
               
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   1 
                 
                 
                   1 
                 
               
             
             . 
           
         
       
     
         [0024]    (3) An (8, 5) code with minimum distance 2 (applicable if M=8): 
         [0000]    
       
         
           
             
               
                 
                   1 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   1 
                 
                 
                   0 
                 
               
               
                 
                   0 
                 
                 
                   1 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   0 
                 
                 
                   1 
                 
               
               
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   1 
                 
               
               
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   1 
                 
                 
                   1 
                 
               
               
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   1 
                 
                 
                   1 
                 
                 
                   1 
                 
               
             
             . 
           
         
       
     
         [0025]    (4) A (9, 5) code with minimum distance 3 (applicable if M=9): 
         [0000]    
       
         
           
             
               
                 
                   1 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   1 
                 
                 
                   1 
                 
               
               
                 
                   0 
                 
                 
                   1 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   1 
                 
               
               
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   1 
                 
                 
                   0 
                 
                 
                   1 
                 
               
               
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   1 
                 
                 
                   1 
                 
                 
                   0 
                 
               
               
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   1 
                 
                 
                   1 
                 
                 
                   1 
                 
                 
                   1 
                 
               
             
             . 
           
         
       
     
         [0026]    (5) A (10, 5) code with minimum distance 4 (applicable if M=10): 
         [0000]    
       
         
           
             
               
                 
                   1 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   1 
                 
                 
                   1 
                 
                 
                   1 
                 
               
               
                 
                   0 
                 
                 
                   1 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   1 
                 
                 
                   1 
                 
               
               
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   1 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   1 
                 
               
               
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   1 
                 
                 
                   1 
                 
                 
                   0 
                 
                 
                   1 
                 
               
               
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   1 
                 
                 
                   1 
                 
                 
                   1 
                 
                 
                   1 
                 
                 
                   0 
                 
               
             
             . 
           
         
       
     
         [0027]    (6) An (11, 5) code with minimum distance 4 (applicable if M=11): 
         [0000]    
       
         
           
             
               
                 
                   1 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   1 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   0 
                 
               
               
                 
                   0 
                 
                 
                   1 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   0 
                 
               
               
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   0 
                 
               
               
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   1 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   1 
                 
                 
                   0 
                 
               
               
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   0 
                 
                 
                   1 
                 
                 
                   1 
                 
                 
                   1 
                 
                 
                   1 
                 
                 
                   1 
                 
                 
                   1 
                 
               
             
             . 
           
         
       
     
         [0028]    It should be noted that the above generator matrices are provided as an example, not as a limitation, and any other variances are also possible. For example, the matrices set forth above may be pre-multiplied and post-multiplied by binary permutation matrices, resulting in new matrices with the rows and/or the columns permuted. This column and/or row permutation will preserve the distance properties of the code. 
         [0029]      FIG. 3  is an example block diagram of a receiving station  300 . The receiving station  300  may be a WTRU, a base station, or any other apparatus or device. The receiving station  300  includes a transceiver  302 , a de-masking unit  304 , and a decoder  306 . The receiving station  300  may optionally further include a mask generator  308 . The transceiver  302  receives a radio block including a PAN field and a masked PCS, such as the one shown in  FIG. 1 . The transceiver  302  outputs the PAN field and the masked PCS. The de-masking unit  304  de-masks the received masked PCS with its own TFI assigned to a TBF or alternatively with a mask generated by the mask generator  308  using its own TFI. The de-masking unit  304  outputs PAN bits and de-masked PCS bits. The decoder  306  then computes a PCS, (e.g., CRC bits), based on the received PAN field and compares the computed PCS with the de-masked received PCS. If the two PCSs agree, then the received PAN field is declared to be addressed to the receiving station  300 . If the two PCSs do not agree, the PAN field is declared to be not addressed to the receiving station  300  and then may be discarded. 
         [0030]    Alternatively, the decoder  306  may compute a PCS, (e.g., using CRC), and then mask the computed PCS with its TFI or a mask generated based on the TFI and then compare the computed masked PCS to the received masked PCS. 
         [0031]    The receiving station  300  may need to decode the received PAN against more than  1  stored TFIs because the receiving station  300  may be allocated more than one TBF, and each TBF has a TFI of its own. When multiple TBFs are allocated to the receiving station  300 , the receiving station  300  determines which TBF the PAN is addressed by de-masking against each possible TFI corresponding to its allocated TBFs. 
         [0032]    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). 
         [0033]    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. 
         [0034]    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.