Hybrid medium access control using token approach in wireless sensor network for high traffic applications

摘要

The evolution of Wireless Sensor Network (WSN) has experienced rapid growth in communication technology. Multimedia is a type of data needed in many applications of WSN. The existing WSN which runs on IEEE 802.15.4 standard mainly deals with low scalar traffic applications such as monitoring of temperature, humidity and pressure. Thus, high traffic application especially video transmission over WSN introduces huge challenges such as dynamic channel conditions, limited resources and delay constraint. The primary objective of this research is to develop reliable Medium Access Control (MAC) protocol that can maintain good quality of service (QoS) with low power consumption for high traffic application. The MAC layer design with token approach protocol namely MAC-TA protocol is proposed for single hop network. The Hybrid MAC namely HMAC-TA which is a combination of Carrier Sense Multiple Access (CSMA) and token approach protocol is proposed for multi-hop network. Both protocols are designed for high traffic scalar data. Then, the HMAC-TA protocol is enhanced to support MPEG-4 video transmission in WSN and the improved protocol is called eHMAC-TA. The proposed MAC protocols ensure low energy consumption by providing a reliable link for data transmission and minimizing the retransmission of packet loss. A cross layer design between MAC and routing protocol is used in token passing decision to ensure the channel is fully utilized by the node that has data to transmit. The token packet is regenerated based on two hops neighbour calculations to avoid token collision. The proposed MAC protocol has been successfully studied and verified through simulation. The eHMAC-TA protocol is verified both with simulation and experimental work. The network performance is measured in terms of packet delivery ratio (PDR), energy consumption and end-to-end (ETE) delay. Additionally for video analysis, peak signal to noise ratio (PSNR) performance is evaluated. Simulation results for single hop network show that MAC-TA protocol is able to maintain the PDR above 90%. This protocol also achieves lower energy consumption by 22.78 Joule, and reduces the ETE delay by 38 ms when compared with existing MAC protocols. The HMAC-TA protocol also outperforms the existing MAC in multi-hop network as it reduces energy consumption by 44%, improves PDR up to 21.39% and reduces ETE delay by 6.97 s. For video analysis using eHMAC-TA protocol, only low motion video is applicable to be transmitted in IEEE 802.15.4 medium when compared to high and medium motion. The simulation results show that eHMAC-TA protocol achieves high PDR which is above 90% and good video quality with PSNR higher than 31 dB compared to existing hybrid MAC protocol. The testbed experiment experiences slightly different result where the PDR is 10% lower than the simulation results. The proposed MAC protocol with token protocol has significantly enhanced the network performance for video application in WSN.