EasiLink: Network Protocol Stack

We propose a cross-layer optimized network protocol stack, namely EasiLink, to study energy efficient data transport in wireless sensor networks (WSNs), which includes MAC protocol, routing protocol and some mechanisms used to guarantee the QoS and energy efficiency requirements, as is shown in the following figure.

• Addressed preamble-based low power listening MAC called EasiMAC, which employs a repeated addressed short preamble to reduce energy consumption and reduce latency: first, it embeds address information of the target in the preamble so that non-target receivers can quickly go back to sleep; second, it uses a short strobed preamble to allow the target receiver to harass the long preamble as soon as it wakes up and determines that it is the target receiver.
• Graded link based routing protocol called EasiRT, which employs a timely and effective graded link evaluation mechanism to balance the traffic load and select the optimal route in order to further reduce energy consumption: first, it grades the link according to the quality which avoids that the highest quality of the link will be the only route selection; second, it uses a slide window-based approach to duly evaluate the qualities of all the links in order to select the optimal route at all time.
• 3) Bandwidth fairness supported congestion control mechanism called EasiCC, in which the source nodes prorate data packets into several transporting priorities, and all the network nodes adjust in-phase packet filtering threshold to adapt network congestion status. With the help of filtering threshold and packet priority, network bandwidth is fairly allotted among data streams. EasiCC uses network access waiting time and packet queue overflowing to detect network congestion, and employs network admittance and queue dropping simultaneously to ensure the integral network performance.

Systems/Experiments

EasiLink has been implemented in WSN test-bed and costs little on the network bandwidth, communication energy and node memory. Simulation and experimental results indicated that EasiLink can limit transmission delay effectively, reduce packet loss ratio remarkably, and provide bandwidth fairness between data streams at the same time.

Accomplishments

1. Tianpu Li, Wei Liu and Li Cui. EasiLPL: An Improved B-Mac Protocol. The 2nd International Conference on Sensor Networks and Applications (SNA'06), Beijing, China, October 2006.
2. Hailing Ju, Li Cui and Changcheng Huang. EasiCC: A congestion control mechanism for WSN. Journal of Computer Research and Development, Vol.45, No.1, 16-25, 2008.