Color-Based Broadcasting for Ad Hoc Networks

Abstract

Abstract-This paper develops a novel color-based broadcast scheme for wireless ad hoc networks where each forwarding of the broadcast message is assigned a color from a given pool of colors. A node only forwards the message if it can assign it a color from the pool which it has not already overheard after a random time. In the closely related counter-based broadcast scheme a node simply counts the number of broadcasts not the colors overheard. The forwarding nodes form a so-called backbone, which is determined by the random timers and, thus, is random itself. Notably, any counter-generated backbone could result from pruning a color-generated backbone; the typical color-generated backbone, however, exhibits a connectivity graph richer than the counter-based ones. As a particular advantage, the colors reveal simple geometric properties of the backbones which we exploit to prove that the size of both, color-and counter-generated backbones are within a small constant factor of the optimum. We also propose two techniques, boosting and edge-growing, that improve the performance of color-and counter-based broadcast in terms of reachability and number of rebroadcasts. Experiments reveal that the powerful boosting method is considerably more effective with the color-based schemes. I. MOTIVATION AND BACKGROUNDIn ad hoc networks, broadcast plays a crucial role, relaying a message generated by one node to all other nodes. Several unicast routing protocols such Dynamic Source Routing (DSR), Ad Hoc On Demand Distance Vector (AODV), Zone Routing Protocol (ZRP), and Location Aided Routing (LAR), as well as multicast protocols employ broadcasting to detect and maintain routes in an ever changing environment.The simplest approach for broadcasting is flooding, where each node rebroadcasts a message as soon as it receives it for the first time. While ensuring a high success rate in reaching all nodes, flooding produces redundant broadcast messages. This redundancy can become overwhelming in dense wireless networks, leading to a loss of precious bandwidth and battery power and to a dramatic degradation of performance, a situation called "broadcast storm" [1].Several broadcast schemes have been developed that avoid broadcast storms. The performance of these schemes is measured in terms of reachability, that is the fraction of the total nodes that receive the broadcast message, the number of rebroadcasts, that is the number of nodes that forward the message, and the latency, that is the time between the first and last instant that the broadcast message is transmitted. The set of nodes which forward the broadcast message form the socalled backbone. Good broadcast schemes ensure reachability close to 1 and simultaneously a small backbone.Broadcast Probabilistic schemes, in contrast, rebuild a backbone from scratch during each broadcast. Nodes make instantaneous local decisions about whether to broadcast a message or not using information derived only from overheard broadcast messages. Consequently these schemes incur a smaller overhead ...

Performance Analysis of Counter-Based Broadcast Scheme for Mobile Ad Hoc Networks

“…In a related work, [8] has proposed a colour-based broadcast scheme in which every broadcast message has a colour-field, with a rebroadcast condition to be satisfied after expiration of the timer similar to counter-based scheme. A node rebroadcasts a message with a new colour assigned to its colour-field if the number of colours of broadcast messages overheard is less than a colour threshold µ.…”

“…The study is conducted using Ns-2 simulator -a discrete event simulator [12] widely used in MANETs community [6][7][8][9][10][11]13,14], to simulate a network of 1000 x1000 m 2 area populated with 20, 40, 60, …, 200 mobile nodes. The simulation model consists of two set of scenario files: topology scenario and traffic generation files.…”

“…Additionally, broadcasting schemes should be localized to satisfy the distributed feature of ad hoc routing protocols. Towards these requirements, a considerable number of schemes have been proposed in the literature [2][3][4][5][6][7][8][9][10][11]. These schemes are commonly divided into two categories: deterministic scheme [2,6] and probabilistic schemes [5,8].…”

“…Nodes make instantaneous local decisions about whether to broadcast a message or not using information derived only from overheard broadcast messages. Consequently these schemes incur a smaller overhead and demonstrate superior adaptability in changing environments when compared to deterministic schemes [8]. However, these schemes have poor reachability as a tradeoff against overhead.…”

“…One major challenge in counter-based schemes is how to select an appropriate C that can optimize the performance of counter-based scheme in terms of number of retransmitting nodes, reachability and end-to-end delay. Most counter-based schemes assumed a counter thresholdvalue of 3 or 4 [5,8]. It has been shown in [2] that a threshold-value of 3 or 4 can save many rebroadcasts in a dense network while achieving a reachability ratio comparable to flooding.…”