Multi-Relay Wireless Cooperative MAC Protocol
Based on Converged Network Coding
Shuangyin Hu
1
,Fangmin Li
2
, Xinhua Liu
1
1. College of Information Engineering, Wuhan University of Technology
2. Dept. of Mathematics and Computer Science, Changsha University
Wuhan, China
husyin@whut.edu.cn, lifangmin@whut.edu.cn, liuxhua@whut.edu.cn
Abstract—In wireless multi-relay cooperative
communication, the relay node forwards the received packets
to the source node and destination node to complete the
two-way collaborati ve communication. However, the problem
of how to control and manage multiple relay nodes to access
the channel has been a research focus. In this case, it makes
use of the number of received packets by relay node to take a
different back-off value to contend for the channel, which can
effectively solve this problem. At the same time, network
coding is effective to increase the cooperation gains and
collaborati ve network throughput, since a number of packets
can be encoded an d transmitted together. By combining with
network coding, it designs an effective cooperati ve MAC
protocol to complete the multi-relay cooperati ve bidirectional
communication. Both theoretical analysis and simulation
results show that the performance of the proposed cooperati ve
MAC protocol in network, particularly in terms of throughput,
is better than the novel network coding-based wireless
cooperative ARQ MAC protocol and the traditional
cooperative MAC protocol.
Keywords—cooperative communication; relay; MAC
protocol
I. INTRODUCTION
Collaborative communication technology originated in
research on the information theory of the relay channel in
the 1970s [1]. Through the relay transmission of the other
nodes in the network, it can expand the coverage, eliminate
blind spots and weak areas, and provide the system capacity
and flexible deployment, which has been applied and
researched in the wireless metropolitan area network,
cellu lar mobile co mmunication network, wireless local area
network and wireless sensor network [2]. MAC protocol, as
an important part of communication network, determines the
way of node access, how to share the wireless channel and
the allocation of limited spectrum resources. The
performance of MAC protocol directly affects the overall
performance of communication network [3]. Therefore, it is
of great significance to study the MAC protocol related
technologies in cooperative wireless communication
networks.
IEEE802.11 is a standard set by the IEEE for wireless
LAN, which includes the physical layer and data link layer,
and has a lot of improved version. The biggest difference
between Wireless cooperative communication and the
general wireless communication is the introduction of a
collaborative node. Due to the introduction of cooperative
nodes, when designing the MAC protocol, many new
problems need to be considered.
According to domestic and foreign researchers, the
problems of how to select the relay node and how the relay
node to complete the transmission, are the core issues of
each researcher's attention. The strategy adopted in [4] is to
select the best relay node according to the instantaneous
state of the relay node channel, and do not need other
additional signals to coordinate the selection of relay nodes.
However, for the problem of hidden terminals, the paper
introduces a three-way handshake mechanism to protect the
cooperative transmission. In [5], three strategies are used to
select the best relay node. The node with the highest
receiving data rate is selected as the candidate node, and
then the condition of the channel is obtained to get the
priority value of the respective node. Finally, the only one
optimal node is selected as the relay node through the k
round analysis. This method of selecting the best relay is
more complex. However the final choice of the relay node
has a better network performance. The advantage of the
strategies is obvious. In [6], a cooperative MAC protocol
based on energy sensing is introduced, and the physical
layer network coding [7] is integrated to improve the
network performance by considering the link status between
the destination queue and source-destination nodes. At the
same time, the selected relay nodes consider the power
allocation algorithm to improve the network life cycle and
to save energy. The above three documents all adopt their
own strategies to select the relay node to complete
cooperative transmission, but the complexity is relatively
high. Especially considering the cross-layer cooperative
transmission, the problems and difficulties which are need
to be solved are greatly increased.
In this paper, a new cooperative MAC protocol is
proposed for multi-relay cooperative communication.
According to the number of packets received by the relay
node, different back-off values are selected to access the
channel and to complete cooperative transmission. The
model established in this paper is two-terminal bidirectional
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