In this paper, we first present a detailed analysis for studying the effect of changing the time difference between two successive channel predictions on the outage probability and the system's reliable transmission rate. Secondly, we propose a low complexity heuristic scheduling algorithm that utilizes long-term ray tracing channel predictions to improve the system throughput in wireless networks. The proposed heuristic algorithm achieves almost identical throughput as the optimal scheduler and outperforms traditional channel-aware schedulers in terms of system's average throughput with low computational cost. The scheduler's performance is tested in the presence of Rayleigh fading and log-normal shadowing effects.

This work considers the development of a realistic statistical model to represent the interference in heterogeneous wireless networks. The considered networks are comprised of one or more femtocells deployed in buildings with unknown internal structures and a preplanned cellular network. The proposed interference model is based on a novel random floor plan generator, which is used to construct a statistical rather than site-specific floor plans. The developed model is augmented with Nakagami fading to represent the femtocell interference signal in the outdoor environment. The model is then utilized to evaluate the performance of the macrocell users where closed-form formulae for the outage probability and signal-to-interference ratio at the receiver front-end are derived. The obtained results reveal that a femtocell signal propagating from an indoor transmitter to an outdoor receiver will experience a composite shadowing/fading process where the Nakagami distribution is adopted for the fading part while the shadowing is modeled by lognormal mixture distribution. Analytical and simulation results show that placing the femtocell base-station (FBS) close to the center of the house can significantly reduce the impact of the interference on the outdoor macrocell users as compared to a randomly placed FBS.

This paper presents an efficient technique to jointly mitigate the severe bit error rate (BER) performance degradation caused by impulsive noise (IN) and multipath fading in broadband transmission systems. The proposed system is based on a low complexity interleaving process applied after the inverse fast Fourier transform (IFFT) in orthogonal frequency division multiplexing (OFDM) systems, hence it is denoted as time-domain interleaving (TDI). The proposed TDI introduces both time and frequency diversity, which can be used to effectively combat impairments such as IN and frequency-selective fading. In addition to its substantial BER reduction capability, the TDI does not degrade the spectral efficiency and has low computational complexity. In frequency-selective fading channels, the BER of the proposed system is mathematically equal to that of Walsh-Hadamard precoded OFDM systems [1]. In presence of IN, analytical and simulation results show that TDI can remarkably reduce the level of the error floors that are commonly observed. Specifically, TDI can achieve a BER of 10-5for less than 1 dB difference from the IN-free case.

This work considers the development of an indoor-to-outdoor signal propagation model, which can be used to analyze and reduce the interference in various wireless communication networks, particularly 4G networks with femtocells and macrocells. The developed model is based on generating a large number of floor plans with random, but realistic, designs and use signal attenuation models to analyze the statistical properties of the signal at a certain distance from the indoor transmitter after penetrating through several layers of construction materials such as wall, doors and windows. Further studies conducted using the developed model demonstrated that the walls and buildings could be exploited to act like a shield that reduces the mutual interference of indoor and outdoor transmitters as in the case of femtocells. As an application, the proposed model is used to investigate the effect of the placement of an indoor transmitter on the signal level outdoors. The obtained results demonstrated that optimizing the location of the indoor transmitter can reduce the power leakage to the outdoor environment by about 18.5 dB.

Hybrid wireless-optical networks provide the inexpensive broadband bandwidth, vital for modern applications, as well as mobility and, scalability required for an access network. However, in order to provide satisfactory Quality of Service (QoS) on such a non-homogeneous network, innovative designs are required. This paper proposes a novel mechanism to significantly improve the delay guarantee, while maintaining throughput, by predicting the incoming traffic to ONUs. Based on the proposed method, two dynamic bandwidth assignment algorithms are proposed. The performance of the proposed algorithms are evaluated by extensive simulations. The results show that the delay bound of delay-sensitive traffic classes, is decreased by a factor of two, while throughput remains the same.