Design of Adaptive Modulation and Coding Scheme for Truncated Hybrid ARQ

Abstract

It has been known that adaptive modulation and coding (AMC) at the physical layer can be combined with a truncated automatic repeat request (ARQ) at the data link layer so as to maximize the spectral efficiency under prescribed delay and error performance constraint. In this paper, we consider the same joint design approach when incremental redundancy-based hybrid ARQ (IR-HARQ) is associated with an AMC design at the physical layer. The extensive simulation studies for predicting the progressive combining gain with each retransmission enables to evaluate the bandwidth efficiency that can be achieved by selecting a more aggressive modulation and coding rate set (MCS) at the expense of packet error rate in earlier transmissions. It has been demonstrated that the aggressive AMC design approach in association with IR-based truncated HARQ can improve bandwidth efficiency by 5.8 and 3.3 dB, as compared to the conservative AMC design approach with truncated HARQ and aggressive AMC design approach with truncated ARQ (i.e., without taking the progressive combining gain in HARQ into account), respectively.

Link adaptation for wireless systems

“…(1) The paper generalizes the closed-form solution derived in [7] for single-link to multi-link (multiple antenna) systems in Rayleigh fading environments. (2) This paper develops a new online framework to calculate SE for both Rayleigh and non-Rayleigh fading channels.…”

“…For Rayleigh fading channel, [7] and the references therein derived a closed-form equation to calculate SE for a single link. The idea is to partition the overall SNR range into .M C 1/ non-overlapping consecutive intervals, with SNR boundary points denoted as f m g M mD0 ; that is, mode m is chosen when D OE m ; mC1 /.…”

“…(2) BLER curve fitting from simulation for mode m transmission n, one curve each, to determine parameters a m;n , g m;n , and m;n [7].…”

“…The works in [5] and [7] address only a single link (SISO) configuration. antennas at the transmitter and N r antennas at the receiver, the order of diversity for the system is N t N r .…”

“…However, Liu et al [5] did not take into account the progressive combining gain of HARQ. The authors in [7] took the same design approach as in [5] to evaluate the improvement in bandwidth (BW) efficiency achieved by the aggressive AMC with respect to the progressive combining gain in IR-HARQ with each retransmission. Various AMC and HARQ joint designs have been studied in literature focusing on single-link performance [8][9][10][11].…”