Method and apparatus for selecting link adaptation parameters for cdma-based wireless communication systems

Abstract

A method and apparatus for selecting a transport format resource combination (TFRC) using an information theoretic approach are provided. The TFRC may be selected in a medium access control (MAC) layer for transmission of data in a code division multiple access (CDMA) wireless communication system. The maximum number of spreading codes available for transmission and the set of possible TFRCs may be determined based on channel characteristics. For each transport block set size (TBSS) in the set of possible TFRCs, a TFRC is selected with the largest number of spreading codes within the maximum number of spreading codes for a corresponding minimum coding rate. The corresponding code rate for each selected TFRCs is compared to a threshold to select a corresponding type of modulation. One of the selected TFRCs is selected to be provided to the physical layer that best matches the CQI and maximizes the TBSS.

What is claimed is: 
     
         1 . A method for use in code division multiple access (CDMA)-based wireless communication, the method comprising:
 receiving a channel quality indicator (CQI) from a wireless transmit/receive unit;   selecting a transport format resource combination (TFRC) based on the CQI, wherein the TFRC defines a transport block size, a number of spreading codes, and a modulation type, and the TFRC is selected with a largest number of spreading codes while maintaining a 1/3 or greater channel coding rate within a total number of available spreading codes; and   transmitting a transport block generated in accordance with the selected TFRC to the WTRU.   
     
     
         2 . The method of  claim 1 , wherein the total number of available spreading codes is limited by a category of the WTRU. 
     
     
         3 . The method of  claim 1 , wherein the TFRC is selected by:
 generating a plurality of TFRCs based on the CQI and a minimum transport block (TB) success probability;   grouping the generated TFRCs based on a transport block set size (TBSS) associated with each generated TFRC;   determining a TFRC for each group based on a number of spreading codes associated with each TFRC in the group that have an acceptable associated code rate for a modulation type; and   selecting a TFRC from the determined TFRCs based on the TBSS associated with each TFRC, the CQI, and the minimum TB success probability.   
     
     
         4 . The method of  claim 1 , wherein the modulation type is selected to maximize the transport block size. 
     
     
         5 . The method of  claim 1 , wherein the modulation type is selected based on a code rate threshold test. 
     
     
         6 . The method of  claim 1 , wherein the TFRC is selected from a predefined CQI-to-TFRC mapping table. 
     
     
         7 . An apparatus for use in code division multiple access (CDMA)-based wireless communication, the apparatus comprising:
 a processor configured to receive a channel quality indicator (CQI) from a wireless transmit/receive unit, select a transport format resource combination (TFRC) based on the CQI, and transmit a transport block generated in accordance with the selected TFRC to the WTRU, wherein the TFRC defines a transport block size, a number of spreading codes, and a modulation type, and the TFRC is selected with a largest number of spreading codes while maintaining a 1/3 or greater channel coding rate within a total number of available spreading codes.   
     
     
         8 . The apparatus of  claim 7 , wherein the total number of available spreading codes is limited by a category of the WTRU. 
     
     
         9 . The apparatus of  claim 7 , wherein the processor is configured to generate a plurality of TFRCs based on the CQI and a minimum transport block (TB) success probability, group the generated TFRCs based on a transport block set size (TBSS) associated with each generated TFRC, determine a TFRC for each group based on a number of spreading codes associated with each TFRC in the group that have an acceptable associated code rate for a modulation type, and select a TFRC from the determined TFRCs based on the TBSS associated with each TFRC, the CQI, and the minimum TB success probability. 
     
     
         10 . The apparatus of  claim 7 , wherein the modulation type is selected to maximize the transport block size. 
     
     
         11 . The apparatus of  claim 7 , wherein the modulation type is selected based on a code rate threshold test. 
     
     
         12 . The apparatus of  claim 7 , wherein the TFRC is selected from a predefined CQI-to-TFRC mapping table.