On the performance of adaptive HARQ with no channel state information feedback

Abstract

This paper presents an adaptive power control scheme for hybrid automatic repeat request (HARQ) systems with no channel state information feedback. The power control process is developed by noting that the throughput of particular HARQ systems may exhibit a staircase behavior. In such scenarios, the throughput remains fixed for a wide range of signalto-noise ratios (SNRs). Consequently, the transmit power can be reduced significantly while the throughput remains almost unchanged. The obtained results reveal that invoking power optimization algorithms can achieve a significant power saving of about 80% for particular scenarios. The system considered in this work is a truncated HARQ with turbo product codes (TPC). Chase combining is also used to combine the retransmitted packets with the original transmission. HARQ acknowledgment/negative acknowledgment (ACK/NACK) feedback is used to estimate the packet error rate from which the system throughput is computed.

Hybrid Automatic Repeat Request (HARQ) in Wireless Communications Systems and Standards: A Contemporary Survey

“…Most of the research work on power adaptive HARQ systems relied on the feedback (CSI) message. In [159], power adaptation is proposed without CSI feedback information. Instead, the transmitter reduces the transmission power with a fixed rate taking into account the received SNR as a feedback message.…”