Fast Antenna Selection Algorithm for Full-duplex
MIMO Communication System
Zhongsheng Liu, Yuanan Liu and Fang Liu
School of Electronic Engineering, Beijing University of Posts and Telecommunications, Beijing, China 100876
Email: {liuzs2013, yuliu, lf}@bupt.edu.cn
Abstract—The combination of full-duplex (FD) technique and
multiple-input multiple-output (MIMO) technique significantly
improves spectral efficiency, while at the same time it increases
hardware cost and complexity. Antenna selection is an effective
approach to mitigate this problem. In this paper, the transmit
antenna selection algorithm for FD bidirectional MIMO system
is studied. At first, the system model and the capacity of
bidirectional communication is formulated. Then, an antenna
selection algorithm based on greedy approach for FD bidirec-
tional MIMO system is proposed, it can achieve almost the same
system capacity as the exhaustive search algorithm with lower
computational complexity. Extensive simulations are conducted
to support the excellent performance of the proposed antenna
selection algorithm, and the capacity of the proposed algorithm
under different signal-to-noise ratio (SNR) and interference-to-
noise (INR) is analyzed.
I. INTRODUCTION
Recently, growing attention has been attached to FD wire-
less communication system, which has the potential to dou-
ble the spectral efficiency. Compared with traditional half-
duplex (HD) communication techniques which divide time
and frequency resources into orthogonal portions for bidi-
rectional communication, FD technique supports simultaneous
transmission and reception in the same frequency band. But,
since the transmit antenna causes strong self-interference to the
receive antenna, the system throughput cannot achieve the de-
sired promotion. However, many self-interference cancellation
methods have been proposed to make FD technique feasible
in practical application, including spatial domain suppression
[1], analog cancellation and digital cancellation [2, 3]. In
addition, MIMO communication technique has received large
attentions over the last decade, due to its capability of boosting
the link reliability and spectral efficiency without the need
for additional power. Considering that both MIMO and FD
employ multiple antenna resources, an important question
raised is how to make the choice between MIMO and FD? [4]
showed that the optimal performance required a combination
of both techniques, which could increase the system capacity
and simplify the procedure of self-interference cancellation.
As the number of antennas in MIMO system grows, a
major limiting factor is the cost of multiple radio frequency
(RF) chains (such as low noise amplifiers, mixers and analog-
to-digital converters) associated with multiple antennas [5].
Antenna selection is an effective technique to reduce the
number of RF chains required, yet preserving the diversity
benefits obtained from the full MIMO system. With antenna
selection, a limited number of RF chains are dynamically
multiplexed among several transmit/receive antennas. In the
case of FD bidirectional MIMO communication systems, the
growing antenna number increases the cost and complexity
of the self-cancellation equipment. Hence, antenna selection
technique plays a significant role in FD transceiver.
Exhaustive search is the optimal selection algorithm over all
possible antenna subsets, while the computational complexity
grows exponentially with the total number of the antennas
available. It is computationally prohibitive, especially when the
channel is fast fading. Several fast antenna selection algorithms
have been proposed in order to make a trade-off between
performance and computational complexity. In [6], a sub-
optimal antenna selection algorithm was raised which removed
the row of the channel matrix that contributed least to the
system capacity in each step. Similarly, an adding antenna
selection algorithm was presented in [7]. These local searching
algorithms though reduce the computational complexity, give
rise to performance loss at the same time. In [8], an antenna
selection algorithm based on the theory of convex optimization
was described, the channel capacity was taken as a function
of the selection diagonal matrix whose diagonal entries valued
in {0, 1}. The performance of this scheme is close to the
optimal algorithm. For the antenna selection technique in FD
communication systems, the self-interference channel between
transmit and receive antennas also shall be considered (except
the channel between the bidirectional transceivers). In [9], a
transmit-receive antenna pair selection scheme was proposed
for bidirectional FD communications, where each transceiver
was equipped with two antennas, used for either transmis-
sion or reception. Four antenna combinations were analyzed
following maximum sum rate criteria and minimum symbol
error criteria. Nevertheless only single transmit RF chain and
receive RF chain are considered in the proposed scheme. In
addition, antenna selection schemes for FD relay system have
been studied in [10, 11].
To the best of our knowledge, most research works on
antenna selection technique are based on HD MIMO or
FD single transmission and single reception system. In this
paper, we study the transmit antenna selection algorithm for
FD bidirectional MIMO communication system. An antenna
selection algorithm based on greedy approach for FD bidi-
rectional MIMO is proposed. Compared with the exhaustive
search algorithm requiring exponential complexity, it can
quite approach the optimal performance with the acceptable