Abstract
Problem statement: A major drawback in the existing protocols in dealing with energy management issues is that the time varying nature of the wireless channels among the ad hoc nodes is ignored. Approach: This study proposed a channel adaptive energy efficient Medium Access Control (MAC) protocol, for efficient packets scheduling and queuing in an ad hoc network, with time varying characteristic of wireless channel taken into consideration. Every node in the proposed scheme estimates the channel and link quality for each contending flow based on which a weight value is calculated and propagated using the routing protocol. Since a wireless link with worse channel quality can result in more energy expenditure, the transmission was allowed only for those flows whose weight is greater than Channel Quality Threshold (CQT). For flows with weight less than CQT, the packets were buffered until the channel and link quality recovers or the weight becomes greater than CQT. To avoid buffer overflow and achieve fairness for the poor quality nodes, a fair scheduling and queuing algorithm is designed where in the CQT is adaptively adjusted on basis of the current incoming traffic load. Results: Simulation results showed that the proposed MAC protocol achieves substantial energy savings with better fairness and increased throughput. Conclusion: The designed protocol provided an efficient packets scheduling and queuing in an ad hoc network, with time varying characteristic of wireless channel taken into consideration.
Highlights
In recent years, more attention has been given to ad-hoc wireless networking, enabling many interesting usage scenarios several challenges are being posed
The interaction between the nodes is in peer-topeer form, whereas the nodes communicate with a centralized base station in case of cellular networks
Since a wireless link with worse channel quality can result in more energy expenditure, the transmission is allowed only for those flows whose weight is greater than Channel Quality Threshold (CQT) value
Summary
More attention has been given to ad-hoc wireless networking, enabling many interesting usage scenarios several challenges are being posed. Overview of our proposed MAC protocol: Packet transmission through a link of high quality consumes less energy than that needed through a “bad” link Based on this observation, in our proposed scheme, each node should possess the ability to decide the state of its communication unit with respect to the current condition of the wireless link between it and the sink. Based on the channel and link quality, a weight value is calculated and propagated along with the data packets using the routing protocol. Fair scheduling and queuing algorithm: The process of buffering packets until the channel threshold constraint is satisfied, is applicable only for nodes with better link quality, since they can always get the most bandwidth shares. Fairness Index: For each CBR flow, we measure the fairness index as the ratio of throughput of each flow and total no. of flows
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