2 research outputs found
Self-interference cancellation for full-duplex MIMO transceivers
PhD ThesisIn recent years, there has been enormous interest in utilizing the full-duplex
(FD) technique with multiple-input multiple-output (MIMO) systems to complement
the evolution of fifth generation technologies. Transmission and reception
using FD-MIMO occur simultaneously over the same frequency band
and multiple antennas are employed in both sides. The motivation for employing
FD-MIMO is the rapidly increasing demand on frequency resources,
and also FD has the ability to improve spectral efficiency and channel capacity
by a factor of two compared to the conventional half-duplex technique.
Additionally, MIMO can enhance the diversity gain and enable FD to acquire
further degrees of freedom in mitigating the self-interference (SI). The
latter is one of the key challenges degrading the performance of systems operating
in FD mode due to local transmission which involves larger power
level than the signals of interest coming from distance sources that are significantly
more attenuated due to path loss propagation phenomena. Various
approaches can be used for self-interference cancellation (SIC) to tackle SI
by combining passive suppression with the analogue and digital cancellation
techniques. Moreover, active SIC techniques using special domain suppression
based on zero-forcing and null-space projection (NSP) can be exploited
for this purpose too. The main contributions of this thesis can be summarized
as follows. Maximum-ratio combining with NSP are jointly exploited in order
to increase the signal-to-noise ratio (SNR) of the desired path and mitigate
the undesired loop path, respectively, for an equalize-and-forward (EF) relay
using FD-MIMO. Additionally, an end-to-end performance analysis of the
proposed system is obtained in the presence of imperfect channel state information
by formulating mathematically the exact closed-form solutions for
the signal-to-interference-plus-noise ratio (SINR) distribution, outage probability,
and average symbol-error rate for uncoded M-ary phase-shift keying
over Rayleigh fading channels and in the presence of additive white Gaussian
noise (AWGN). The coefficients of the EF-relay are designed to attain
the minimum mean-square error (MMSE) between the transmission symbols.
Comparison of the results obtained with relevant state-of-the-art techniques
suggests significant improvements in the SINR figures and system capacity.
Furthermore, iterative detection and decoding (IDD) are proposed to mitigate
the residual self-interference (SI) remaining after applying passive suppression
along with two stages of SI cancellation (SIC) filters in the analogue
and digital domains for coded FD bi-directional transceiver based multiple
antennas. IDD comprises an adaptive MMSE filter with log-likelihood ratio
demapping, while the soft-in soft-out decoder utilizes the maximum a posteriori
(MAP) algorithm. The proposed system’s performance is evaluated in
the presence of AWGN over non-selective (flat) Rayleigh fading single-input
multiple-output (SIMO) and MIMO channels. However, the results of the
analyses can be applied to multi-path channels if orthogonal frequency division
multiplexing is utilised with a proper length of cyclic prefix in order to
tackle the channels’ frequency-selectivity and delay spread. Simulation results
are presented to demonstrate the bit-error rate (BER) performance as a
function of the SNR, revealing a close match to the SI-free case for the proposed
system. Furthermore, the results are validated by deriving a tight upper
bound on the performance of rate-1=2 convolutional codes for FD-SIMO and
FD-MIMO systems for different modulation schemes under the same conditions,
which asymptotically exhibits close agreement with the simulated BER
performance.Ministry of Higher Education and Scientific Research
(MoHESR), and the University of Mosul and to the Iraqi Cultural Attache in
London for providing financial support for my PhD scholarship
MIMO Systems
In recent years, it was realized that the MIMO communication systems seems to be inevitable in accelerated evolution of high data rates applications due to their potential to dramatically increase the spectral efficiency and simultaneously sending individual information to the corresponding users in wireless systems. This book, intends to provide highlights of the current research topics in the field of MIMO system, to offer a snapshot of the recent advances and major issues faced today by the researchers in the MIMO related areas. The book is written by specialists working in universities and research centers all over the world to cover the fundamental principles and main advanced topics on high data rates wireless communications systems over MIMO channels. Moreover, the book has the advantage of providing a collection of applications that are completely independent and self-contained; thus, the interested reader can choose any chapter and skip to another without losing continuity