Realistic and Efficient Multi-Channel Communications in Wireless Sensor Networks

Abstract

Abstract-This paper demonstrates how to use multiple channels to improve communication performance in Wireless Sensor Networks (WSNs). We first investigate multi-channel realities in WSNs through intensive empirical experiments with Micaz motes. Our study shows that current multi-channel protocols are not suitable for WSNs, because of the small number of available channels and unavoidable time errors found in real networks. With these observations, we propose a novel tree-based multichannel scheme for data collection applications, which allocates channels to disjoint trees and exploits parallel transmissions among trees. In order to minimize interference within trees, we define a new channel assignment problem which is proven NPcomplete. Then we propose a greedy channel allocation algorithm which outperforms other schemes in dense networks with a small number of channels. We implement our protocol, called TMCP, in a real testbed. Through both simulation and real experiments, we show that TMCP can significantly improve network throughput and reduce packet losses. More importantly, evaluation results show that TMCP better accommodates multi-channel realities found in WSNs than other multi-channel protocols.

Exploiting Overlapping Channels for Minimum Power Configuration in Real-Time Sensor Networks

“…Previous work [6] has reported that adjacent overlapping channels have undesired inter-channel interferences. In this section, we first investigate the impacts of overlapping channels on packet reception ratio (PRR) of link to motivate our work.…”

“…However, no detailed study has been performed to utilize overlapping channels in wireless sensor networks for improved real-time performance. A coarse-grained channel assignment policy for WSNs is proposed in [6], which allocates nonoverlapping channels to disjoint trees and exploits parallel transmissions among trees. In this paper, we propose to utilize overlapping channels to configure power and channels for a WSN to achieve better real-time performance and energy efficiency.…”

“…While multi-channel communications have shown great promise, recent studies (e.g., [6]) conducted experiments on Micaz hardware to investigate multichannel realities in wireless sensor networks. An important reality reported is that the number of orthogonal channels is actually small for the existing mote hardware.…”

“…Accordingly, it has been suggested that a practical multi-channel communication protocol should only rely on a small number of non-adjacent orthogonal channels, because adjacent overlapping channels may have undesired inter-channel interferences. For example, at most, only 8 channels out of the 16 channels provided by the CC2420 radio chip can be used as orthogonal channels [6], resulting in the waste of half of the available wireless channel resources. While 8 channels may be enough for some WSN applications, using only orthogonal channels has limited the further improvement of network throughput, real-time performance, and power optimization in the commonly used many-to-one traffic pattern, where the number of data flows can be large in a network.…”

MUSIKA: A multichannel multi-sink data gathering algorithm in wireless sensor networks

“…Tree-based Multi-Channel Protocol (TMCP) [2] supports data collection traffic by partitioning the network into multiple subtrees and then assigns different channels to different subtrees. Hence, inter-tree interference is minimized without the need for time synchronization.…”