Varying the modulation constellation and/or constellation labellings within a packet retransmitted using the Hybrid Automatic Repeat Request (HARQ) technique

摘要

A hybrid automatic repeat request method for communicating between a first transceiver 702 and a second transceiver 704 where the first transceiver 702 receives an indication from the second transceiver 704 that a transmission of one or more portions of a data packet has been unsuccessfully received. A modulation strategy is determined based on an estimated increase in the robustness of receiving one or more portions of the data packet at the second transceiver 704 and is used in retransmitting the one or more portions of the data packet. Modulation strategies are determined by selecting one or more modulation constellations and/or one or more modulation labelling for use in modulating one or more portions of the data packet. The second transceiver 704 receives the one or more portions of the data packet and processes the data packet by using the determined modulation strategy and performing iterative detection 722 and decoding 724 to take advantage of the estimated increase in robustness to reception. The receiver may also perform Chase combining. Use of EXIT charts in the strategy selection process is also disclosed.