Journal of Systems Engineering and Electronics
Vol. 24, No. 2, Apr il 2013, pp.215–221
Complex field network-coded cooperation based on
multi-user detection in wireless networks
Jing Wang
1, 2,*
, Xiangyang Liu
3
, Kaikai Chi
4
, and Xiangmo Zhao
1
1. School of Information Engineering, Chang’an University, Xi’an 710064, China;
2. State Key Laboratory of Integrated Service Networks, Xidian University, Xi’an 710071, China;
3. Department of Network Management, Xi’an Communication College, Xi’an 710106, China;
4. College of Computer Science and Technology, Zhejiang University of Technology, Hangzhou 310023, China
Abstract:
Cooperative communication can achieve spatial di-
versity gains, and consequently combats signal fading due to
multipath propagation in wireless networks powerfully. A novel
complex field network-coded cooperation (CFNCC) scheme based
on multi-user detection for the multiple unicast transmission is pro-
posed. Theoretic analysis and simulation results demonstrate that,
compared with the conventional cooperation (CC) scheme and
network-coded cooperation (NCC) scheme, CFNCC would obtain
higher network throughput and consumes less time slots. More-
over, a further investigation is made for the symbol error probabil-
ity (SEP) performance of CFNCC scheme, and SEPs of CFNCC
scheme are compared with those of NCC scheme in various sce-
narios for different signal to noise ratio (SNR) values.
Keyw ords: network coding, complex field, wireless network, co-
operative communication, multi-user detection.
DOI: 10.1109/JSEE.2013.00028
1. Introduction
Spatial d iversity is well known as one of the most effective
ways to combat fading in wireless channels. Multiple input
multiple output (MIMO) can implement spatial diversity,
but requires multiple antennas to be placed sufficiently far
apart [ 1], which may be p roblematic for size-limited mo-
bile terminals and impractical. The cooperative communi-
cation is an alternative approach proposed to provide spa-
tial diversity [2]. So far, various protocols for cooperative
communication were p roposed [3–5]. It is well known that,
in all these conventional cooperation p rotocols, a relay can
Manuscript received December 10, 2011.
*Corresponding author.
This work was supported by the National Natural Science Foundation
of China (61040005; 61001126; 61271262), the China Postdoctoral Sci-
ence Foundation Funded Project (20110491638; 2012T50789), the Nat-
ural Science Foundation of Shannxi Province of China (2011JQ8036),
the Special Fund for Basic Scientific Research of Central Colleges
(CHD2012ZD005), and the Research Fund of Zhejiang University of
Technology (20100244).
only help one single source-destination pair at a certain
time instance.
The idea of network coding was first proposed to
enhance the capacity of the noiseless wired network
[6]. Since the broadcast nature of the wireless medium al-
lows a relay to overhear data from multiple sources for
free, integrating the concept of network coding in coo-
perative communication has attracted much research at-
tention. Joint n etwork-channel coding schemes based on
turbo codes and low density parity check (LDPC) codes
were proposed for the multiple-access relay channels re-
spectively [7,8]. The diversity gain offered by implement-
ing network coding is investigated over wireless commu-
nication networks containing the distributed antenna sys-
tem as well as the multi-user cooperation [9]. In consider-
ation of the conventional cooperation (CC) which allows
the relay to simply process and forward what the relay has
heard, network-coded cooperation endows network coding
capability with the relay [10,11]. Then an opportunistic
network coded cooperation scheme suitable for multiple
unicast transmission pairs in a single-cell wireless network
was proposed in [12].
Due to the effect of interference in wireless networks,
all the relays and d estination nodes cannot receive several
signals at the same time. Through mapping the superposi-
tion of electromagnetic signals to simple Galois field (GF)
additions of digital bit streams, physical-layer network co-
ding (PNC) can achieve information exchange between
two so urces in two time slots [13,14]. To further improve
the network throughput, the complex field network cod-
ing approach was introduced recently in [15,16], which
entailed symbol-level operations at the physical layer, and
offered a better fit than the GF network coding.
Considering that the complex field network coding is
only studied in the simple scenario of multiple sources
transmitting to a common destination [15,16], a novel