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

Wireless networks, because of their many advantages in comparison with the wired ones, have become the predominant technology for deployment of communications infrastructure. WiMAX (Worldwide Interoperability for Microwave Access), which is an industry branding for IEEE 802.16 Wireless Metropolitan Area Network (MAN) sets of standard [1, 2], provides wireless access to mobile devices with a range of Quality of Service (QoS) guarantees for various types of applications. There are diverse versions of IEEE 802.16 standard, but IEEE 802.16e [3] also known as Mobile WiMAX, is the most well-known version, though newer versions have also been formulated.

/pdf/key-management-in-mobile-wimax-networks-48ggpyrrjh.pdf

Key Management in Mobile WiMAX Networks

This paper proposes a cooperative sensing algorithm based on distributed fusion strategy and maintained probability of false alarm for cognitive radio. It further introduces a reporting strategy that discusses how cooperative sensing in distributed manner can select among possible candidates in order to reduce bandwidth requirement. We adopted a dynamic distributed architecture for cooperative sensing based on the link quality and found condition on the channel quality for cooperation to be beneficial. Using probability of detection, and BER metrics we evaluated the performance improvement of distributed cooperation over direct cooperation and noncooperative sensing. We used analytical formulation with possible candidate selection criteria to investigate and maximize the cooperation gain. By employing such distribution and selection technique, the reporting error due to the fading channel is reduced. Results show that the method effectively improve performance of sensing, it increase the probability of detection up to 0.9 at <0.1 probability of false alarm. Sensitivity requirement is reduced with network scale and the number of nodes participate in decision fusion is reduced about 42% at probability of false alarm 0.1. ROC curve has obvious improvement compared with existing methods.

http://archive.apan.net/meetings/Hanoi2010/Session/Slides/NetworkResearch/paper/Wireless_DistributedCooperativeSpectrumSensing.pdf

Distributed Cooperative Spectrum Sensing in Cognitive Radio Networks with Adaptive Detection Threshold

The expectation of network performance from the early days of ARPANET until now has been changed si gnificantly. Every day, new advancement in technological infrast ructure opens the doors for better quality of service and accordi ngly level of perceived quality of network services have been inc reased over the time. Nowadays for many applications, late informat ion has no value or even may result in financial or catastrophic los s, on the other hand, demands for some level of guarantee in providing an d maintaining quality of service are ever increasing. Based on th is history, having a QoS aware routing system which is able to provide t oday's required level of quality of service in the networks and eff ectively adapt to the future needs, seems as a key requirement for future Internet. In this work we have extended the traditional AntNet routin g system to support QoS with multiple metrics such as bandwidth and delay which is named Q-Net. This novel scalable QoS routi ng system aims to provide different types of services in the netwo rk simultaneously. Each type of service can be provided for a period o f time in the network and network nodes do not need to have any p revious knowledge about it. When a type of quality of servi ce s requested, Q-Net will allocate required resources for the serv ice and will guarantee QoS requirement of the service, based on target objectives. Keywords—Quality of Service, Routing, Ant Colony Optimization, Ant-based algorithms .

Q-Net: A Novel QoS Aware Routing Algorithm for Future Data Networks

In sphere decoding the choice of sphere radius is crucial to excellent performance. In Chan-Lee sphere decoding - based algorithm, the problem of choosing initial radius has been solved by making the radius sufficiently large, thus increasing the size of the search region. In this paper we present maximum likelihood decoding using simplified sphere decoder as apposed to the original sphere decoder for the detection of cubic structure quadrature amplitude modulation symbols. This simple algorithm based on Chan-Lee sphere decoder allows the search for closest lattice point in a reduced complexity manner compared to original sphere decoder for multiple input multiple output system with perfect channel state information at the receiver. Results show symbol error rate has stabilized even at very low initial value of the square radius.

/pdf/a-simplified-sphere-decoding-algorithm-for-mimo-transmission-1xminiavju.pdf

A Simplified Sphere Decoding Algorithm for MIMO Transmission System

Dalam makalah ini, kami menyelidik prestasi M–Modulasi Amplitud Kuadratur terkod–Gray dalam sistem penghantaran menggunakan skema Multiplexan Pembahagian Frekuensi Ortogonal (OFDM) melalui saluran hingar Gaussian (AWGN). QAM terkod Gray dengan 1 bit ke 8 bit per simbol bersamaan dengan 2–QAM ke 256–QAM dijana dan dimasukkan ke dalam sistem penghantaran OFDM. Prestasi sistem dalam bentuk kadar ralat bit (BER) diberi berbanding saiz jelmaan Fourier pantas (FFT), bilangan sub-pembawa, panjang prefix-kitaran, dan toleransi terhadap nisbah isyarat kepada hingar (SNR) dalam saluran. Dapatan awal menunjukkan hanya modulasi 16–QAM ke bawah boleh diterimapakai untuk mencapai BER sebanyak 10 –3 dengan SNR sekurang-kurangnya 20 dB. Peringkat modulasi yang lebih tinggi seperti 256–QAM memerlukan SNR sebanyak 50 dB untuk mencapai hasil BER yang sama. Kajian juga menunjukkan prestasi sistem ini tidak tergugat dengan perubahan saiz FFT mahupun panjang prefix-kitaran yang dimasukkan ke dalam isyarat yang dihantar. Walau bagaimanapun, bilangan sub-pembawa bergantung kepada peringkat QAM yang digunakan untuk suatu nilai SNR yang diberi. 
				
				Kata kunci: Multiplexan pembahagian frekuensi ortogonal (OFDM), modulasi kuadratur (QAM), pengkodan gray, dan jelmaan fourier pantas
				
				In this paper, we investigate the performance of Gray encoding M–Quadrature Amplitude Modulation (QAM) schemes in Orthogonal Frequency Division Multiplexing (OFDM) transmission over added white Gaussian noise (AWGN) channel. Gray–coded QAM with 1 to 8–bit symbol corresponding to 2 to 256–QAM respectively is generated and fed into OFDM transmission system. Performance in terms of bit error rate (BER) is presented against OFDM fast Fourier transform (FFT) size, subcarrier number, length of cyclic prefix, and tolerance to signal to noise ratio of the channel. Preliminary results show that only 16 and lower level–QAM are attractive to achieve a bit error rate (BER) of 10 –3 with signal to noise ratio of at least 20 dB. The higher level QAM such as 256–QAM scheme will require at least a SNR of 50 db to achieve similar outcome. The study also shows that the performance of the system is not affected by the number of fft–points used, or the length of cyclic prefix inserted to the transmitted signal. However, the number of subcarriers does depend on the level of QAM used at a given SNR value.
			
				Keywords: Orthogonal frequency division multiplexing (OFDM), quadrature amplitude modulation (QAM), gray coding, fast fourier transform (FFT)

Preliminary Investigation of Gray Coded M–Quadrature Amplitude Modulation in Orthogonal Frequency Division Multiplexing Over Additive White Gaussian Noise Channel

Borhanuddin Mohd Ali

Papers

Key Management in Mobile WiMAX Networks

Distributed Cooperative Spectrum Sensing in Cognitive Radio Networks with Adaptive Detection Threshold

Q-Net: A Novel QoS Aware Routing Algorithm for Future Data Networks

A Simplified Sphere Decoding Algorithm for MIMO Transmission System

Preliminary Investigation of Gray Coded M–Quadrature Amplitude Modulation in Orthogonal Frequency Division Multiplexing Over Additive White Gaussian Noise Channel