Abstract
Multi-channel assignments are becoming the solution of choice to improve performance in single radio for wireless networks. Multi-channel allows wireless networks to assign different channels to different nodes in real-time transmission. In this paper, we propose a new approach, Multi-channel Distributed Coordinated Function (MC-DCF) which takes advantage of multi-channel assignment. The backoff algorithm of the IEEE 802.11 distributed coordination function (DCF) was modified to invoke channel switching, based on threshold criteria in order to improve the overall throughput for wireless sensor networks (WSNs) over 802.11 networks. We presented simulation experiments in order to investigate the characteristics of multi-channel communication in wireless sensor networks using an NS2 platform. Nodes only use a single radio and perform channel switching only after specified threshold is reached. Single radio can only work on one channel at any given time. All nodes initiate constant bit rate streams towards the receiving nodes. In this work, we studied the impact of non-overlapping channels in the 2.4 frequency band on: constant bit rate (CBR) streams, node density, source nodes sending data directly to sink and signal strength by varying distances between the sensor nodes and operating frequencies of the radios with different data rates. We showed that multi-channel enhancement using our proposed algorithm provides significant improvement in terms of throughput, packet delivery ratio and delay. This technique can be considered for WSNs future use in 802.11 networks especially when the IEEE 802.11n becomes popular thereby may prevent the 802.15.4 network from operating effectively in the 2.4 GHz frequency band.
Highlights
Wireless Sensor Networks (WSNs) [1,2,3,4] are used over a wide range and in varying fields such as military application, environmental monitoring, medical care, smart buildings and other industries.WSNs sensors are generally deployed randomly in the field of interest, delivering myriad types of events from simple periodic reports to unpredictable bursts of messages triggered by external events that are being sensed
When a node wants to transfer data the Carrier Sense (CS) mechanism is invoked in order to determine if the channel is busy or idled
During the backoff period the contention window (CW) parameter will reach its threshold after the third attempt and switch channel
Summary
WSNs sensors are generally deployed randomly in the field of interest, delivering myriad types of events from simple periodic reports to unpredictable bursts of messages triggered by external events that are being sensed. These sensor nodes will work collaboratively to sense a given environment, perform in-network computations and communicate with a base station when a targeted event occurs. The current WSNs paradigm has some interesting features including self-organization, dynamic network topology and multi-hop routing. These are important features for many real world applications nowadays
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