7 research outputs found
Performance Analysis of MIMO-MRC in Double-Correlated Rayleigh Environments
We consider multiple-input multiple-output (MIMO) transmit beamforming
systems with maximum ratio combining (MRC) receivers. The operating environment
is Rayleigh-fading with both transmit and receive spatial correlation. We
present exact expressions for the probability density function (p.d.f.) of the
output signal-to-noise ratio (SNR), as well as the system outage probability.
The results are based on explicit closed-form expressions which we derive for
the p.d.f. and c.d.f. of the maximum eigenvalue of double-correlated complex
Wishart matrices. For systems with two antennas at either the transmitter or
the receiver, we also derive exact closed-form expressions for the symbol error
rate (SER). The new expressions are used to prove that MIMO-MRC achieves the
maximum available spatial diversity order, and to demonstrate the effect of
spatial correlation. The analysis is validated through comparison with
Monte-Carlo simulations.Comment: 25 pages. Submitted to the IEEE Transactions on Communication
Performance Analysis of a Two-Hop MIMO Mobile-to-Mobile via Stratospheric-Relay Link Employing Hierarchical Modulation
Next generation wireless communication networks intend to take advantage of the integration of terrestrial and aerospace infrastructures. Besides, multiple-input multiple-output (MIMO) architecture is the key technology, which has brought the wireless gigabit vision closer to reality. In this direction, high-altitude platforms (HAPs) could act as relay stations in the stratosphere transferring information from an uplink to a downlink MIMO channel. This paper investigates the performance of a novel transmission scheme for the delivery of mobile-to-mobile (M-to-M) services via a stratospheric relay. It is assumed that the source, relay, and destination nodes are equipped with multiple antennas and that amplify-and-forward (AF) relaying is adopted. The performance is analyzed through rigorous simulations in terms of the bit-error rate (BER) by using a recently proposed 3D geometry-based reference model in spatially correlated flat-fading MIMO channels, employing a hierarchical broadcast technique and minimum mean square error (MMSE) receivers
Investigation of non-binary trellis codes designed for impulsive noise environments
PhD ThesisIt is well known that binary codes with iterative decoders can achieve
near Shannon limit performance on the additive white Gaussian noise
(AWGN) channel, but their performance on more realistic wired or wireless
channels can become degraded due to the presence of burst errors
or impulsive noise. In such extreme environments, error correction alone
cannot combat the serious e ect of the channel and must be combined
with the signal processing techniques such as channel estimation, channel
equalisation and orthogonal frequency division multiplexing (OFDM).
However, even after the received signal has been processed, it can still
contain burst errors, or the noise present in the signal maybe non Gaussian.
In these cases, popular binary coding schemes such as Low-Density
Parity-Check (LDPC) or turbo codes may not perform optimally, resulting
in the degradation of performance. Nevertheless, there is still scope
for the design of new non-binary codes that are more suitable for these
environments, allowing us to achieve further gains in performance. In
this thesis, an investigation into good non-binary trellis error-correcting
codes and advanced noise reduction techniques has been carried out with
the aim of enhancing the performance of wired and wireless communication
networks in di erent extreme environments. These environments
include, urban, indoor, pedestrian, underwater, and powerline communication
(PLC). This work includes an examination of the performance
of non-binary trellis codes in harsh scenarios such as underwater communications
when the noise channel is additive S S noise. Similar work
was also conducted for single input single output (SISO) power line communication
systems for single carrier (SC) and multi carrier (MC) over
realistic multi-path frequency selective channels. A further examination
of multi-input multi-output (MIMO) wired and wireless systems on
Middleton class A noise channel was carried out. The main focus of the
project was non-binary coding schemes as it is well-known that they outperform
their binary counterparts when the channel is bursty. However,
few studies have investigated non-binary codes for other environments.
The major novelty of this work is the comparison of the performance
of non-binary trellis codes with binary trellis codes in various scenarios,
leading to the conclusion that non-binary codes are, in most cases,
superior in performance to binary codes. Furthermore, the theoretical
bounds of SISO and MIMO binary and non-binary convolutional coded
OFDM-PLC systems have been investigated for the rst time. In order
to validate our results, the implementation of simulated and theoretical
results have been obtained for di erent values of noise parameters and
on di erent PLC channels. The results show a strong agreement between
the simulated and theoretical analysis for all cases.University of
Thi-Qar for choosing me for their PhD scholarship and the Iraqi Ministry
of Higher Education and Scienti c Research (MOHESR) for granting me
the funds to study in UK. In addition, there was ample support towards
my stay in the UK from the Iraqi Cultural Attach e in Londo
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