Anas F. Al Rawi

Performance Analysis of Full-Duplex-MRC-MIMO With Self-Interference Cancellation Using Null-Space-Projection

In this paper, the performance analysis of a full-duplex maximum ratio combining multiple-input multiple-output (FD-MRC-MIMO) system based on equalize-and-forward (EF) relaying with self-interference-cancellation (SIC) is derived under imperfect channels state information (CSI). The performance of the system is investigated in the presence of additive white Gaussian noise (AWGN) over Rayleigh fading channels. Self-interference cancellation is performed by applying null-space-projection (NSP) via singular-value-decomposition (SVD). Furthermore, exact, closed-form solutions for the signal-to-interference-plus-noise ratio (SINR) distribution and outage probability are mathematically formulated and evaluated along with the average symbol-error-rate (ASER) for M-ary phase-shift keying (M-PSK) modulation. The coefficients of the EF-relay are obtained to attain the minimum mean square error (MMSE) between the transmission symbols. Comparison of the obtained results with relevant state-of-the-art techniques suggests significant improvements in the SINR figures and system capacity.

Pareto-metaheuristic multi-objective network optimization for OFDMA-based systems

In this paper, a new planning method is proposed for the next generation wireless networks that are based on Orthogonal Frequency Division Multiple Access (OFDMA). As a consequence of the wide variety service demands in terms of data rate and Quality of Service (QoS), the traffic pattern is considered to be heterogeneous. Therefore, the complexity of obtaining Base Stations (BSs) positions increases with the randomness of the traffic distribution. In addition to this challenge, the capacity of each BS is limited due to power and bandwidth constraints, propagation losses, Gaussian antenna pattern, and the Co-Channel Interference (CCI), which in turn increase the complexity measures for an efficient network design. According to Nash Equilibrium, combined efficient systems must perform equally to achieve certain performance. This implies that the traffic of a cellular system should be equally distributed over all the BSs to achieve the highest network performance. Hence, we formulate the planning problem as a non-linear multi-objective optimization problem. The optimum solution should not dominate the throughput of one BS over the others and this is referred to as Pareto optimal. However, loading all cells equally may not be possible in certain traffic distributions. Therefore, the proposed method tends to approach the optimal solution by tackling the problems of BS positioning and resource allocation simultaneously. We adopt a hybrid approach, i.e. Pareto-Metaheuristic (PMH) that achieves a balanced throughput over all cells as well as minimizing the number of the installed BSs targeting a certain service outage probability. Simulation results show that, in addition to maximizing the individual cell throughput, the network throughput variation decreases as the number of iteration increases.

Game Theoretic Framework for Future Generation Networks Modelling and Optimization

A new cost efficient automated planning and optimization method is proposed for OFDMA future-generation cellular networks targeting throughput maximization. The mathematical formulation is a non-linear multi-objective optimization problem subject to minimum interference, cost and similar resource constraints at each cell within a defined heterogeneous traffic environment. The fundamental objective is to maximize the individual cell throughput without deteriorating it over other cells, which results in a throughput equilibrium maximization over multiple cells. This implicitly implies traffic and co-channel interference congestion avoidance across the network whilst maintaining both cost efficiency and quality of service (QoS) policies. Optimal solution existence is subject to the network size, traffic and computational complexity constraints which converges to a throughput equilibrium or alternatively to the well known Nash Equilibrium (NE).

Discrete Multi-Tone Digital Subscriber Loop Performance in the Face of Impulsive Noise

As an important solution to “the last mile” access, digital subscriber loops (DSLs) are still maintained in a huge plant to support low-cost but high-quality broadband network access through telephone lines. The discrete multi-tone (DMT) transmissions constitute a baseband version of the ubiquitous orthogonal frequency division multiplexing. While the DMT is ideally suited to deal with the frequency selective channel in DSL, the presence of bursty impulsive noise tends to severely degrade the transmission performance. In this paper, we analyze the statistics of impulsive noise and its effects on the received signals, with the aid of a hidden semi-Markov process. The closed-form bit error rate expression is derived for the DMT system for

Dynamic planning for OFDMA networks: Resource, interference and traffic congestion management

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Joint Impulsive Noise Estimation and Data Detection Conceived for LDPC-Coded DMT-Based DSL Systems

-ary quadrature amplitude modulation under practical noise conditions and for measured dispersive DSL channels. Instead of relying on the simplified stationary and impulsive noise process, our noise model considers both the temporal and spectral characteristics based on the measurement results. The simulation results confirm the accuracy of the formulas derived and quantify the impact both of the impulsive noise and of the dispersive channel in DSL.

Bi-directional beamforming bit error ratio analysis for wireline backhaul networks

In this paper, a new network planning framework is proposed for orthogonal frequency-division multiple access (OFDMA) cellular systems based on co-channel interference and traffic congestion avoidance. The network planning is formulated as a non-linear multi-objective optimization problem subject to minimum interference and related resource constraints at each cell under heterogeneous traffic. The multi-objective problem is represented by the throughput maximization of each single cell without penalizing the remaining cells, which results in a throughput equilibrium over the whole network. The fundamental objective is to maximize the throughput balance and, hence, traffic and co-channel interference congestions are avoided across the network. In order to maximize the equilibrium, the optimization problem is decomposed into a positioning problem and a resource allocation problem, which are solved by parallel heuristics and convex optimization. Additionally, a novel rotated polarization assignment method is proposed to minimize further the effect of the co-channel interference.

Fair scheduling and hybrid resource allocation in OFDMA cellular system

Impulsive noise is one of the most challenging issues in digital subscriber lines (DSL). In order to mitigate the deleterious effects of impulsive noise, the conventional automatic repeat request invokes cyclic redundancy checking (CRC) in order to estimate the existence of impulsive noise and then triggers retransmission, which degrades the spectral efficiency attained. More straightforward techniques of mitigating impulsive noise, such as blanking and clipping, require specific design, which increases the implementation complexity. Against the background, we propose a novel two-stage joint impulsive noise estimation and data detection scheme conceived for low-density parity-check (LDPC) coded discrete multitone (DMT)-based DSL systems. More explicitly, first of all, we propose a semi-blind estimation method, which is capable of estimating the arrival of impulsive noise without using CRC and additionally evaluating the power of impulsive noise with an adequate accuracy. Second, in order to improve the accuracy of impulsive noise estimation in more advanced LDPC-coded DMT-based DSL systems, we propose a decision-directed method for the second stage of channel decoding and data detection with the aid of extrinsic information transfer (EXIT) charts. Our proposed two-stage scheme is capable of approaching the performance of the idealistic scenario of perfectly knowing both the arrival time and the instantaneous power of impulsive noise. Moreover, we analyze the mean square error of the proposed schemes in order to quantify the estimation accuracy and to reduce the estimation complexity. Our simulation results demonstrate that our proposed scheme is capable of achieving a near-capacity performance to using our LDPC coded DMT-based DSL system in the presence of impulsive noise.

User priority aware scheduling and dynamic resource allocation in orthogonal frequency division multiple access

The next generation of digital subscriber line (DSL) standard will require the development of enabling technologies to exploit currently unused higher frequencies in the very and ultra high frequency bands over a shorter copper drop. At these higher frequencies, the indirect channels produced by the electromagnetic coupling (EMC) between pairs in a binder cable may be as strong as, or stronger than, the direct channels. In this work, we exploit the isomorphism between this wireline environment and the well-studied multipath wireless models to propose a full duplex wired MIMO system for the legacy copper connection in a point-to-point backhaul network. The proposed system achieves self-interference suppression and exploitation of the diversity offered by the EMC channels through a joint interoperable precoding scheme consisting of null space projection (NSP) and maximum ratio combining (MRC). Channel measurements for a 10 pair binder cable are used to evaluate the performance of the proposed system.