Design of Adaptive Modulation and Coding Scheme for Truncated HARQ

In this paper, a new design approach for an adaptive modulation and coding scheme, combined with the truncated hybrid ARQ (HARQ) in the emerging broadband mobile Internet access systems, is proposed. The progressive combining gain can be obtained by the number of retransmissions in HARQ schemes, as the target packet error rate can vary with each retransmission. In other words, higher bandwidth efficiency can be achieved by selecting a more aggressive modulation and coding rate set (MCS) at the expense of packet error rate of earlier transmissions, which can be compensated by the progressive retransmission gain in HARQ. Based on extensive simulation for predicting the combining gain in each retransmission, it has been demonstrated that bandwidth efficiency can be improved as much as 5.8dB and 3.3dB, compared with the conservative AMC design approach with truncated HARQ and aggressive AMC design approach with truncated ARQ, respectively