False positive acknowledgement for cooperative small cell assisted Hybrid ARQ

Small cell overlay combined with unitary frequency reuse is one of the most promising deployment options to satisfy the ever increasing rate demand in beyond 4G cellular networks. It has been shown that cooperation between small base stations and macro base stations has a great potential in these hierarchical deployments. However, a significant number of cooperation strategies require that small base stations be reached through low latency and high speed backhaul links. The latency of this backhaul is often an obstacle to efficient cooperation between macro cell and small cell layers. To answer this problem we provide a protocol based on hybrid ARQ procedure combined with a parsimonious use of over-the-air communications between small base stations and macro base stations. The proposed protocol is compatible with latency figures that are observed on affordable digital subscriber links. The performance of this protocol are assessed and compared to conventional LTE hybrid ARQ strategy using theoretical derivations and numerical experiments. Significant gains are observed on the reverse links in 3GPP LTE context.