Performance of distributed mechanisms for flow admission in wireless adhoc networks

TL;DR

This paper analyzes distributed algorithms for flow admission in wireless ad hoc networks, focusing on low-overhead solutions that approximate optimal scheduling under interference constraints modeled by conflict graphs.

Contribution

It provides performance bounds for distributed algorithms in wireless networks, highlighting the role of graph invariants like the induced star number.

Findings

Distributed algorithms have bounded performance gaps from optimal solutions.

Performance bounds depend on graph invariants such as the induced star number.

Certain classes of networks exhibit predictable performance within these bounds.

Abstract

Given a wireless network where some pairs of communication links interfere with each other, we study sufficient conditions for determining whether a given set of minimum bandwidth quality-of-service (QoS) requirements can be satisfied. We are especially interested in algorithms which have low communication overhead and low processing complexity. The interference in the network is modeled using a conflict graph whose vertices correspond to the communication links in the network. Two links are adjacent in this graph if and only if they interfere with each other due to being in the same vicinity and hence cannot be simultaneously active. The problem of scheduling the transmission of the various links is then essentially a fractional, weighted vertex coloring problem, for which upper bounds on the fractional chromatic number are sought using only localized information. We recall some distributed algorithms for this problem, and then assess their worst-case performance. Our results on this fundamental problem imply that for some well known classes of networks and interference models, the performance of these distributed algorithms is within a bounded factor away from that of an optimal, centralized algorithm. The performance bounds are simple expressions in terms of graph invariants. It is seen that the induced star number of a network plays an important role in the design and performance of such networks.