《《Throughput Optimization in High Speed Downlink Packet Access (HSDPA)》.pdf

474 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS, VOL. 10, NO. 2, FEBRUARY 2011 Throughput Optimization in High Speed Downlink Packet Access (HSDPA) Tao Cui, Feng Lu, Vignesh Sethuraman, Anil Goteti, Subramanya P. N. Rao, and Parvathanathan Subrahmanya Abstract鈥擨n this paper, we investigate single user throughput called Channel Quality Indicator (CQI), is an indication of optimization in High Speed Downlink Packet Access (HSDPA). the highest data rate that the UE can reliably receive in the Speci铿乧ally, we propose of铿俰ne and online optimization algo- existing conditions on the downlink wireless channel. The rithms which adjust the Channel Quality Indicator (CQI) used by the network for scheduling of data transmission. In the of铿俰ne frequency of reporting CQI is con铿乬ured by the network, algorithm, a given target block error rate (BLER) is achieved by and is typically set to once every few milliseconds. Using adjusting CQI based on ACK/NAK history. By sweeping through the channel quality reports, the Node B accordingly schedules different target BLERs, we can 铿乶d the throughput optimal data on the High Speed Physical Downlink Shared Channel BLER of铿俰ne. This algorithm could be used not only to optimize (HS-PDSCH). The Node B鈥檚 selection of the transport block throughput but also to enable fair resource allocation among multiple users in HSDPA. In the online algorithm, the CQI offset size (TBS, number of information bits per packet), number is adapted using an estimated short term throughput gradient of channelization codes, modulation and resource allocation without the need for a target BLER.