On the optimal number of hops in linear wireless ad hoc networks with hybrid ARQ

In this paper, we study the optimal design of a linear wireless multihop network that employs Hybrid Automatic Repeat reQuest (HARQ) protocols in a quasi-static fading environment. Data transmission is assumed to be delay-tolerant up to a certain predefined maximum delay (in transmission slots) that is larger or equal to the number of hops. Multihop routing is implemented through a time-division scheduling and decode-and-forward relaying. Excess time is exploited for retransmissions using either HARQ Type I or Chase Combining protocols on the hops that result in link-outage. Relying on analysis and numerical optimization, we seek answer to the following question: given the maximum allowed delay and signal-to-noise ratio, what is the optimal number of hops that maximizes the end-to-end throughput?