A Minimum Average-Delay Configuration Algorithm for Relay-Assisted HARQ Transmissions
Vasile Bota, Mihály Varga · 2020
The paper studies the minimum average delay and corresponding maximum spectral efficiency provided by a relay-assisted Hybrid-ARQ algorithm (CHARQ), which operates under target Block-Error Rate (BLERgt) and maximum delay constraints. The analysis is performed by selecting adaptively a set of QAM-modulation and coding schemes (MCs), over Rayleigh block-faded channels. It presents an algorithm mADMSE that configures CHARQ by selecting the MC which would require the smallest number of retransmissions and provide the greatest spectral efficiency for the current SNRs of the involved channels, while observing the constraints of BLERgt and maximum number of retransmissions allowed. CHARQ's performances are compared to those of a HARQ algorithm that operates only on the direct link, both configured by mAD-MSE. The results obtained show that CHARQ ensures BLERgt at smaller SNR values and requires smaller average number of rounds, at low SNR values, than HARQ, but provides smaller spectral efficiency.