Backwards composite feedback for configurable ultra-reliability of retransmission protocols

Future wireless networks envision ultra-reliable, ultra-low latency communication with efficient use of the limited wireless channel resources. Closed-loop retransmission protocols, such as automatic repeat request (ARQ), where retransmission of a packet is enabled using a feedback channel has been adopted since early days of wireless telecommunication to achieve the required reliability. The performance of such protocols is strongly dependent on the feedback channel reliability. Focusing on the problem of feedback errors, a new method of acknowledging packet delivery to overcome unreliability of feedback channel is proposed in this paper. The proposed method is based on backwards composite acknowledgment of multiple packets and provides the transmitter with additional design parameters to configure ultra-reliable communication for a user depending on channel quality. Numerical analysis are presented showing orders of magnitude increase in reliability for the proposed method compared to traditional ARQ at the cost of a small increase in average experienced delay.