Multilevel Control Signaling for Hybrid ARQ

In this paper, we propose and analyze a multi-level acknowledgement scheme for hybrid ARQ (H-ARQ) systems, which modifies a general ACK/NAK signals to represent multilevel information. For instance, the other signals except the ACK/NAK signals may be used for scheduling of retransmission in H-ARQ scheme, which results in increasing the resolution of uplink channel estimation signals. Simulation results demonstrate that, when the retransmission interval is set to optimal length, the proposed H-ARQ scheme shows 0.5-2 dB gain with properly selected parameters.