Cooperative MIMO MAC protocol using STTC in wireless sensor networks
J. Adline Vidhya, G. Kalpana, P. Dananjayan · WSEAS TRANSACTIONS on COMMUNICATIONS archive · 2010
Sensor networks require robust and energy efficient communication protocols to maximise the network lifetime. Radio irregularity, channel fading and interference results in larger energy consumption and latency for packet transmission over wireless channel. Cooperative transmission of data using multi-input multi-output (MIMO) scheme is used to combat channel fading and improve the communication performance of distributed wireless systems. However, an inefficiently designed medium access control (MAC) protocol may diminish the performance gains of MIMO operation. Hence this paper develops a distributed MAC protocol for packet transmissions using fixed group size cooperative MIMO utilising space time trellis code (STTC) to achieve high energy savings and lesser delay. Further, to ensure the stability of transmission queue at the sender, this paper also proposes a threshold based MAC protocol for MIMO transmission. The protocol uses thresholding scheme that updates dynamically the cooperative group size based on the queue length at the sending node. The performance of the fixed group size MIMO MAC protocol using STTC technique is evaluated for various orders of diversity in terms of transmission error probability, energy consumption and delay. Simulation results are also provided to evaluate the performance of threshold based MAC protocol. Results show that 4×4 cooperative group size is dynamically selected as the cooperative group size as it provides minimum energy and delay. Cooperative transmission using STTC technique provides significant performance improvement than uncoded scheme due to the exploitation of MIMO diversity gain.