Throughput-Delay-Reliability Tradeoff with ARQ in Wireless Ad Hoc Networks

TL;DR

This paper analyzes the tradeoffs between throughput, delay, and reliability in wireless ad hoc networks using ARQ, deriving optimal retransmission strategies and showing single-hop transmission's optimality in sparse networks.

Contribution

It introduces a framework for joint delay-reliability and throughput-delay-reliability tradeoffs with ARQ, and derives optimal retransmission allocations and hop strategies.

Findings

Optimal retransmission allocation maximizes transmission capacity.

Single-hop transmission is optimal in sparse networks.

Derived bounds on throughput under delay and reliability constraints.

Abstract

Delay-reliability (D-R), and throughput-delay-reliability (T-D-R) tradeoffs in an ad hoc network are derived for single hop and multi-hop transmission with automatic repeat request (ARQ) on each hop. The delay constraint is modeled by assuming that each packet is allowed at most $D$ retransmissions end-to-end, and the reliability is defined as the probability that the packet is successfully decoded in at most $D$ retransmissions. The throughput of the ad hoc network is characterized by the transmission capacity, which is defined to be the maximum allowable density of transmitting nodes satisfying a per transmitter receiver rate, and an outage probability constraint, multiplied with the rate of transmission and the success probability. Given an end-to-end retransmission constraint of $D$, the optimal allocation of the number of retransmissions allowed at each hop is derived that maximizes a lower bound on the transmission capacity. Optimizing over the number of hops, single hop transmission is shown to be optimal for maximizing a lower bound on the transmission capacity in the sparse network regime.