An Upper Bound on Multi-hop Transmission Capacity with Dynamic Routing Selection

TL;DR

This paper establishes upper bounds on the transmission capacity of multi-hop wireless networks with dynamic routing, highlighting the benefits of path diversity and the limitations of fixed routing in interference-limited environments.

Contribution

It derives a closed-form upper bound on transmission capacity considering dynamic route selection and analyzes the impact of network parameters and relay randomness.

Findings

Dynamic routing outperforms fixed routing in interference-limited networks.

More hops do not increase throughput once interference dominates.

Relay randomness and channel variability enhance network capacity.

Abstract

This paper develops upper bounds on the end-to-end transmission capacity of multi-hop wireless networks. Potential source-destination paths are dynamically selected from a pool of randomly located relays, from which a closed-form lower bound on the outage probability is derived in terms of the expected number of potential paths. This is in turn used to provide an upper bound on the number of successful transmissions that can occur per unit area, which is known as the transmission capacity. The upper bound results from assuming independence among the potential paths, and can be viewed as the maximum diversity case. A useful aspect of the upper bound is its simple form for an arbitrary-sized network, which allows insights into how the number of hops and other network parameters affect spatial throughput in the non-asymptotic regime. The outage probability analysis is then extended to account for retransmissions with a maximum number of allowed attempts. In contrast to prevailing wisdom, we show that predetermined routing (such as nearest-neighbor) is suboptimal, since more hops are not useful once the network is interference-limited. Our results also make clear that randomness in the location of relay sets and dynamically varying channel states is helpful in obtaining higher aggregate throughput, and that dynamic route selection should be used to exploit path diversity.