Abstract
Reliable and efficient real-time transmission is an important and challenging issue for wireless sensor networks (WSNs). Truncated retransmission times and relay selection can effectively reduce transmission delay and improve system throughput. A new direct multisource multirelay cooperative automatic repeat request (D-MSMR-CARQ) protocol based on truncation with two relay selection methods in WSNs is analytically analyzed in this paper. Firstly, based on two different relay selection methods under the maximum ratio combining (MRC), the discrete time Markov chain (DTMC) model of D-MSMR-CARQ protocol and state space is established. Secondly, for each D-MSMR-CARQ protocol based on different relay selection method, we obtain the closed-form expressions of the system average transmission delay and the expressions of the system throughput through state transition probabilities. Finally, numerical results reveal that the first relay selection method outperforms the second relay selection method on the average transmission delay performance for the proposed protocol. More specifically, the delay performance of the proposed protocol can be improved by 13% compared with the nondirect-link protocol when the channel environment is the same; the proposed protocol improves the throughput performance by 47% compared with the nondirect protocol when the channel environment is harsh under the same simulation parameters. Furthermore, the optimal number of source nodes and relay nodes is determined.
Highlights
With the progress of wireless mobile communication technology and Internet of things (IoT), wireless sensor networks (WSNs) have broad application prospects in many fields such as environmental monitoring [1,2,3], smart agriculture [4], smart city [5, 6], and smart grid [7, 8]
For the proposed protocols under two relay selection methods, the protocol based on the first relay selection method has better delay and throughput performance. irdly, direct-link transmission cannot be ignored when the channel environment is harsh. e reason is that for the MSMR-cooperative ARQ (CARQ) with nondirect-link protocol, our proposed protocol improves the delay performance by 13%; our proposed protocol improves the throughput performance by 47% when the packet error rate (PER) from the source node to the destination node is 0.8
We have proposed a D-MSMR-CARQ protocol based on truncation with two relay selection methods
Summary
With the progress of wireless mobile communication technology and Internet of things (IoT), WSNs have broad application prospects in many fields such as environmental monitoring [1,2,3], smart agriculture [4], smart city [5, 6], and smart grid [7, 8]. Rahman et al [22] considered the K-means estimation approach in 2-tier WSNs and selected the closest relay node to the base station to reduce energy consumption; the delay and throughput performance were not analyzed. (2) Based on two different relay selection schemes, we obtain the best relay node and summarize the packet transmission process of the D-MSMR-CARQ protocol into two DTMC models and derive the state space, respectively. (3) For each D-MSMR-CARQ protocol based on different relay selection methods, we derive the closedform expressions of the average transmission delay by using the average PER and the expressions of the throughput by the state transition probabilities, respectively.
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