Online capacity maximization in wireless networks

  • Authors:
  • Alexander Fanghänel;Sascha Geulen;Martin Hoefer;Berthold Vöcking

  • Affiliations:
  • Dept. of Computer Science, RWTH Aachen University, Aachen, Germany;Dept. of Computer Science, RWTH Aachen University, Aachen, Germany;Dept. of Computer Science, RWTH Aachen University, Aachen, Germany;Dept. of Computer Science, RWTH Aachen University, Aachen, Germany

  • Venue:
  • Journal of Scheduling
  • Year:
  • 2013

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Abstract

In this paper we study a dynamic version of capacity maximization in the physical model of wireless communication. In our model, requests for connections between pairs of points in Euclidean space of constant dimension d arrive iteratively over time. When a new request arrives, an online algorithm needs to decide whether or not to accept the request and to assign one out of k channels and a transmission power to the request. Accepted requests must satisfy constraints on the signal-to-interference-plus-noise (SINR) ratio. The objective is to maximize the number of accepted requests.Using competitive analysis we study algorithms using distance-based power assignments, for which the power of a request relies only on the distance between the points. Such assignments are inherently local and particularly useful in distributed settings. We first focus on the case of a single channel. For request sets with spatial lengths in [1,Δ] and duration in [1,Γ] we derive a lower bound of 驴(Γ驴Δ d/2) on the competitive ratio of any deterministic online algorithm using a distance-based power assignment. Our main result is a near-optimal deterministic algorithm that is O(Γ驴Δ(d/2)+驴 )-competitive, for any constant 驴0.Our algorithm for a single channel can be generalized to k channels. It can be adjusted to yield a competitive ratio of O(k驴Γ 1/k驴驴Δ(d/2k驴)+驴 ) for any factorization (k驴,k驴) such that k驴驴k驴=k. This illustrates the effectiveness of multiple channels when dealing with unknown request sequences. In particular, for 驴(log驴Γ驴log驴Δ) channels this yields an O(log驴Γ驴log驴Δ)-competitive algorithm. Additionally, we show how this approach can be turned into a randomized algorithm, which is O(log驴Γ驴log驴Δ)-competitive even for a single channel.