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

Coping with customer interests to employ Wireless Sensor Networks (WSN) in the new applications requires dealing with the fact of nodes variety that implies the heterogeneous nature of the traffic. This necessitates employing differentiation techniques that lead in the end to implementing prioritization in some processes of the system. The medium access controlling process plays a main role in the WSN work life cycle and the QoS provisioning is mainly based on the MAC efficiency. In this paper, we introduce the main techniques of WSN medium access prioritizing in the cluster-based Low-PANs. We propose using the prioritizing source as the categorizing factor. Furthermore, this study analyzes the impact of applying the MAC prioritization on the performance of the WSN. The simulation results prove that prioritizing nodes improves the system performance in terms of the access delay and the throughput metrics.

/pdf/medium-access-prioritizing-in-the-heterogeneous-low-rate-acl4b6bhtc.pdf

Medium access prioritizing in the heterogeneous low-rate wireless PANs

In this paper we present an adaptive multiple antenna selection (AdMAS) employing a maximum of 4 transmit (4 Tx) and 1 receive (1 Rx) antenna in conjunction with coded space-time-frequency (STF) orthogonal frequency division multiplexing (OFDM) over broadband wireless access IEEE 802.16 Stanford Interim University (SUI) channels. Our coded STF-OFDM is a product of phase-shift-keying (PSK) modulated STF block code which has been concatenated with convolutional codes of rate 1/3, constant length of 8, and code generator of [225 331 367]. In transmitting data we adaptively select channel(s) with least fade and turn off the most faded channel(s) at the transmitter side. We determine levels of fading of the channel from each transmitter based on the calculated second moment of the channel impulse response (CIR). We also compare results when level of fading is based on the mean of the CIR. We tested our scheme in the most severe case of SUI channel, i.e SUI6. Results show that the employment of AdMAS does not give significant gain at low-level constellations. However significant gain is observed at higher constellations which makes our proposed scheme a potential scheme to be employed for the high data rate system.

Coded space-time-frequency OFDM employing adaptive multiple antenna selection (AdMAS) in broadband wireless access

A new technique of producing multiple Brillouin Stokes was described utilizing a linear cavity of hybrid Brillouin/Erbium fiber laser. Twenty-one lines of multiple Brillouin Stokes with 10.88 GHz line spacing were obtained from this architecture.

21-line of multiple Brillouin Stokes incorporating a linear cavity of hybrid BEFL

In Mobile WiMAX, a Base Station (BS) delivers security keys to Mobile Stations (MSs) through a key distribution scheme to guarantee security and access control. The MSs need to perform ciphering operations to access the keys upon rekeying process. In this way, the MSs consume energy to receive and decrypt the keys for further communication with a BS, while the BS consumes energy to encrypt and transmit the keys. In current key distribution schemes, any member join or leave event results in a key updating, and the duration of the MSs stay in the cell is not important, but on average low speed MSs tend to stay longer in the cell, while fast MSs will leave the cell faster. This paper proposes an Efficient Key Distribution scheme to decrease the number of exchanged keys which results in minimizing energy consumption of the network by grouping the MSs into the different subgroups based on their speeds using complete binary tree. Analysis shows that the proposed scheme reduces energy consumption during key updating process.

/pdf/a-novel-energy-efficient-key-distribution-scheme-for-mobile-3e2tjyxh4l.pdf

A Novel Energy Efficient Key Distribution Scheme for Mobile WiMAX Networks

Throughout the history of wireless communications, spatially diverse antenna array systems have being important in improving the radio link between wireless users Moreover, this system is proposed to reduce the multipath fading through its narrowly directive radiation beam The introduction of an interference free window in the delay domain from the new LAS-CDMA standard has received much attention for furthering research on multipath delay spread In this paper, we studied the effect of angular spread on maximum excess delay in multipath propagation environments Then, we examined the application of antenna arrays in the LAS-CDMA standard to overcome this multipath phenomenon First of all, the multipath propagation literature is reviewed, followed by the explanation of maximum angular spread in a simple discrete ring of scatterers model Comparison analyses are made between the conventional omnidirectional antenna and narrow beam antenna array Finally, the analytical performances in term of power delay profile are presented

/pdf/study-of-antenna-array-based-multipath-propagation-36nw9y0tvl.pdf

Borhanuddin Mohd Ali

Papers

Medium access prioritizing in the heterogeneous low-rate wireless PANs

Coded space-time-frequency OFDM employing adaptive multiple antenna selection (AdMAS) in broadband wireless access

21-line of multiple Brillouin Stokes incorporating a linear cavity of hybrid BEFL

A Novel Energy Efficient Key Distribution Scheme for Mobile WiMAX Networks

Study of antenna array based multipath propagation phenomenon in LAS-CDMA standard