It is shown that, particularly for terrestrial cellular telephony, the interference-suppression feature of CDMA (code division multiple access) can result in a many-fold increase in capacity over analog and even over competing digital techniques. A single-cell system, such as a hubbed satellite network, is addressed, and the basic expression for capacity is developed. The corresponding expressions for a multiple-cell system are derived. and the distribution on the number of users supportable per cell is determined. It is concluded that properly augmented and power-controlled multiple-cell CDMA promises a quantum increase in current cellular capacity. >

On the capacity of a cellular CDMA system

Praise for the Third Edition: "This is one of the best books available. Its excellent organizational structure allows quick reference to specific models and its clear presentation . . . solidifies the understanding of the concepts being presented."IIE Transactions on Operations EngineeringThoroughly revised and expanded to reflect the latest developments in the field, Fundamentals of Queueing Theory, Fourth Edition continues to present the basic statistical principles that are necessary to analyze the probabilistic nature of queues. Rather than presenting a narrow focus on the subject, this update illustrates the wide-reaching, fundamental concepts in queueing theory and its applications to diverse areas such as computer science, engineering, business, and operations research.This update takes a numerical approach to understanding and making probable estimations relating to queues, with a comprehensive outline of simple and more advanced queueing models. Newly featured topics of the Fourth Edition include:Retrial queuesApproximations for queueing networksNumerical inversion of transformsDetermining the appropriate number of servers to balance quality and cost of serviceEach chapter provides a self-contained presentation of key concepts and formulae, allowing readers to work with each section independently, while a summary table at the end of the book outlines the types of queues that have been discussed and their results. In addition, two new appendices have been added, discussing transforms and generating functions as well as the fundamentals of differential and difference equations. New examples are now included along with problems that incorporate QtsPlus software, which is freely available via the book's related Web site.With its accessible style and wealth of real-world examples, Fundamentals of Queueing Theory, Fourth Edition is an ideal book for courses on queueing theory at the upper-undergraduate and graduate levels. It is also a valuable resource for researchers and practitioners who analyze congestion in the fields of telecommunications, transportation, aviation, and management science.

Fundamentals of Queueing Theory

Information Theory and Reliable Communication

This document provides updates to IEEE Std 802.16's MIB for the MAC, PHY and asso- ciated management procedures in order to accommodate recent extensions to the standard.

IEEE Standard for Local and Metropolitan Area Networks Part 16: Air Interface for Fixed Broadband Wireless Access Systems Draft Amendment: Management Information Base Extensions

Ultra Wideband Signals and Systems in Communication Engineering

Recently, the revolution of deploying wireless sensor network (WSN) technology has accelerated the need for further development. Thus, numerous researches of different perspectives seeking some enhancements have been proposed. Throughout our extensive study, we have found that there is a phenomenon with adverse side effects known as sink isolation (sink's hotspot zone) which exists due to the sink's neighbor nodes (deputy nodes) run out of energy faster than the others. This draws attention to our hypothesis, energy exhaustion in sink's hotspot zones is worthy of concern more than that of distant zones. Accordingly, we propose a pioneering metric with highly influential factors for forward node selection. This proper selection ends the route of the data traffic in a deputy node of least energy exhaustion. As a result, extensively dissipated sensors in the hotspot zones are avoided, sinks are protected from isolation, and lifetime is extended.

/pdf/work-in-progress-a-proposal-for-a-hotspot-metric-to-extend-j9xr27s7sw.pdf

Work in progress: A proposal for a hotspot metric to extend the lifetime in wireless sensor network

This paper present a novel performance enhancement for combined code division multiple access (CDMA) and space division multiple access (SDMA) scheme using SDMA grouping on top of code and spatial signatures. This paper is divided into two parts. In the first part, the system performance of combined CDMA-SDMA scheme is evaluated under Additive White Gaussian Noise (AWGN) channel for a single sectored cell. A fixed number of available codes L kept in a central pool can be utilized by K users, where, K>L. The same code can be assigned to a group of users according to their angle of arrival (which is known as SDMA group). Here, the analytical model of bit error rate (BER) for any arbitrary number of users has been derived and evaluated. In the second part of this paper, a simple code assignment algorithm is proposed to assign a already used code to a new user by which, the orthogonality between users can be maximized. The results show that the system capacity is noticeably improved with the combined system compared to the pure CDMA system. Further enhancement can be obtained when SDMA grouping is considered with orthogonal code assignment to users those belongs to different SDMA groups. Finally, the code assignment algorithm shows that high number of users can be accommodated by a fixed small number of codes.

Combined CDMA-SDMA Performance Analysis and Code Assignment Algorithm

Improving the Performance of TCP in LEO Satellite Environment

In practice, diffraction and scattering from oblique surfaces create waves that travel in three-dimensional (3-D) space and arrive at the receiver with both azimuth and elevation angles. In this paper, 3-D signal scattering is considered. Generalized analytical expressions for the spatial and temporal signal fading correlations are derived, and numerically evaluated, for a uniform linear array (ULA) in terms of the antenna elements spacing and statistical distributions of the angles of arrival (AOAs). The results show that the effect of the elevation angle distribution on the spatial correlation values in case of vertically separated antenna elements is much more significant than that on horizontally separated antenna elements

/pdf/spatial-and-temporal-fading-correlation-of-uniform-linear-1i7pk1yluv.pdf

Spatial and Temporal Fading Correlation of Uniform Linear Antenna Array in Three-Dimensional Signal Scattering

This paper proposes a new resource allocation algorithm for uplink OFDMA-based cooperative relay networks, assuming multiple user nodes, multiple relay nodes and a single destination. The aim is to maximise the total sum of the users' data rates, while guaranteeing fairness among them with different QoS requirements. Assuming perfect channel state information (CSI) at the resource allocation controller, the optimisation problem is formulated such that each user is assigned a weight factor based on its QoS requirements. The ones with higher weights are given higher priorities to select their resources (relay stations and subcarriers) first. Once the required QoS is achieved for all users, the weight factor for all users is reduced to a small uniform value. The remaining resources are then allocated to the users with higher instantaneous rates in order of magnitude. The results show that the proposed algorithm outperforms the greedy and static algorithms in terms of outage probability and fairness, and at the same time outperforms Jeong's algorithm by 58% in terms of total sum rate, with an average 74% reduction in system complexity.

/pdf/a-low-complexity-resource-allocation-algorithm-for-ofdma-sei25ix4c8.pdf

Borhanuddin Mohd Ali

Papers

Work in progress: A proposal for a hotspot metric to extend the lifetime in wireless sensor network

Combined CDMA-SDMA Performance Analysis and Code Assignment Algorithm

Improving the Performance of TCP in LEO Satellite Environment

Spatial and Temporal Fading Correlation of Uniform Linear Antenna Array in Three-Dimensional Signal Scattering

A Low Complexity Resource Allocation Algorithm for OFDMA Cooperative Relay Networks with Fairness and QoS Guaranteed