Approximation Algorithms for Interference Aware Broadcast in Wireless Networks

Broadcast is a fundamental operation in wireless networks and is well supported by the wireless channel. However, the interference resulting from a node's transmission pose a key challenge to the design of any broadcast algorithms/protocols. In particular, it is well known that a node's interference range is much larger than its transmission range and thus limits the number of transmitting and receiving nodes, which inevitably prolong broadcast. To this end, a number of past studies have designed broadcast algorithms that account for this interference range with the goal of deriving a broadcast schedule that minimizes latency. However, these works have only taken into account interference that occurs within the transmission range of a sender. Therefore, the resulting latency is non-optimal given that collision occurs at the receiver. In this paper, we address the Interference-Aware Broadcast Scheduling (IABS) problem, which aims to find a schedule with minimum broadcast latency subject to the constraint that a receiver is not within the interference range of any senders. We study the IABS problem under the protocol interference model, and present a constant approximation algorithm, called IABBS, and its enhanced version, IAEBS, that produces a maximum latency of at most 2 [pi/root 3 (alpha + 1)(2) + (pi/2 + 1) (alpha + 1) + 1] R, where alpha is the ratio between the interference range and the transmission range, i.e., alpha >= 1, and R is the radius of the network with respect to the source node of the broadcast. We have evaluated our algorithms under different network configurations and confirmed that the latencies achieved by our algorithms are much lower than existing schemes. In particular, compared to CABS, the best constant approximation broadcast algorithm to date, the broadcast latency achieved by IAEBS is 5/8 that of CABS.