Random access sequence set design in wireless cellular communication networks

Expressions are derived that make it possible to calculate and optimize the spectral efficiency (SE) of multiple-input-multiple-output (MIMO) cellular wireless communication systems (WCSs) with allowance for the interaction of radiators in the receiving and transmitting antennas of the MIMO systems, the properties of the deterministic radio channel, and the presence of directionally concentrated interference. The effect of the interaction of radiators on the SE of the MIMO systems is studied, and the efficiency of the MIMO technology is analyzed on the basis of the model example of two receiving and two transmitting antennas with a conducting screen placed in between them. It is demonstrated that, in comparison to single-channel-transmission technology, MIMO technology allows an increase the WCS SE only at relatively high values of the signal-to-interference-plus-noise ratio at the receiver input and in the case of nearly equal channel gains. It is shown that the relative positions of the transmitter and receiver at which the MIMO-WCS SE can be significantly increased are dependent on the channel energy and are substantially limited at real powers transmitted under urban conditions.

The objective of this presentation is to illustrate that an electromagnetic macro modeling can properly predict the path loss exponent in a mobile cellular wireless communication system. This represents the variation of the path loss with distance from the base station antenna. Specifically, it will be shown that the path loss exponent is 3 preceded by a slow fading region and followed by the fringe region where the path loss exponent is 4. The size of these regions is determined by the height of the base station antenna. The relevant theory starts from the analysis of radiation from a vertical electric dipole situated over a horizontal imperfect ground plane as first considered by Sommerfeld in 1909. The various methods used to evaluate the Sommerfeld integrals are described for different regions. Then, accurate numerical analyses and experimental data will illustrate the above statements, validating the theory. Moreover, the experimental data reveal that a macro modeling of the environment using an appropriate electromagnetic analysis can accurately predict the path loss exponent for the propagation of radio waves in a cellular wireless communication system scenario without needing to recourse to other types of micromodeling.

This paper proposes a new paradigm of shared spectrum access between cellular wireless communications (CWC) and radio astronomy systems (RAS). Traditionally, most spectrum chunks are separately allocated to CWC and RAS, with a few shared spectrum without guaranteed spectrum access for RAS. Furthermore, RAS sites are generally set up at remote locations, protected by radio quiet zones. In view of growths in spectrum demands from both systems, in population, and in applications and service deployments, the existing paradigm of geographical and spectral isolation between CWC and RAS will become inefficient. This paper develops a three phase spectrum access which enables geographical and spectral coexistence between CWC and RAS. Additionally, traffic statistics based improved spectrum access is developed. Furthermore, a built-in fine tuning mechanism is presented for addressing mismatches between design and practical environments as well as for facilitating service evolutions. Performance evaluation results demonstrate advantages of the proposed paradigm.

Location determination and hearability coverage has become very important today. Many applications from navigation to automated billing are utilized position as a major parameter. Evaluation of mobile station position is therefore important to assess GPS coordinates availability at certain area. The result will be used to recommend whether any supporting system such as Wi-Fi, transponder or new base station should be installed to enhance hearability. This paper presents the assessment of GPS and A-GPS data availability in UKM campus including position accuracy and signal strength. The result shows GPS signals are available in all part in studied area but some parts can't be localizing by A-GPS. The hearability based on Global Navigation Satellite System is high, however low hearability based on cellular wireless communication system.

The non-line-of-sight (NLOS) propagation caused by intermittently blocking of the direct path between the base station and the mobile station is the main difficulty for mobile user location in cellular wireless communication system. So it is indispensable to investigate the techniques about the NLOS error identification and correction. In this paper, we suggest a robust and accurate approach using probability density function (PDF) estimator to identify the NLOS situation, and then an improved biased Kalman filter which depends on PDF estimator as the nonlinearity weighting coefficient in recursive operation is used to mitigate the NLOS error for time of arrival (TOA) measurements. As the PDF estimator is calculated from actual TOA samples, it is adaptive for the complex practical NLOS environments. The simulation results also indicate that with the less prior information about communication environments, the approach we present has a good location performance even in severe NLOS situations.

This paper presents a novel analytical derivation of the false alarm probability (FAP) and detection probability (DP) for non-line-of-sight (NLOS) detection based on LTE signals. Position estimation in indoor or urban area with cellular wireless communication systems is getting more and more important. However, especially in these environments NLOS propagation causes positioning errors in the order of hundreds of meters. Thus, detection and mitigation of NLOS signals is a critical task. In this paper, we derive the FAP and DP on power-scaled detectors based on LTE multipath signals. The derivation considers frequency-selective fading channels taking sub-sample multipath interference, channel dynamics and initial frequency offsets into account. The results show a simple way to calculate the DP versus FAP. Simulation results verify the analytical probabilities for the WINNER II C2 channel model. Additionally, the simulations show the improved FAP of an antenna array at the receiver.

This is the second issue of Wireless Communications and Mobile Computing (WCMC) published by John Wiley & Sons, Ltd. The first issue was published ahead of time and presented some excellent review papers from experts in the field. We received great feedback from a number of colleagues about its content and we promise to continue producing excellent issues in the future. If you did not receive your sample copy of the inaugural issue, please let me or any of the regional editors know to arrange to send you a copy. We have selected seven papers to appear in this second issue. These papers span a good range of topics in the area. The first is a review paper by Ralph and Aghvami. They discuss the Wireless Application Protocol (WAP) architecture and characteristics. Then, they investigate the devices that are supported by WAP as well as the drivers and services. These services include quality of service, security, billing, interoperability, and performance engineering. The variety of media types combined with the diversity of Internet connection characteristics raises momentous challenges to the achievement of ubiquitous access to Internet multimedia content. The second paper, by Margaritidis and Polyzos, addresses issues related to this topic. They identify the importance of adaptation to this category. Then, they examine several important factors that influence the design and optimization of the adaptation architecture. In conclusion, they describe current commercial solutions and future trends in application adaptation in conjunction with recent developments towards wireless access to the Internet. The third paper, by Havinga and Smit, discusses also wireless multimedia networking, but focuses more on energy efficiency. The authors identify three key problems and provide possible solutions to overcome them. The efficient management of power-controlled cellular wireless systems is necessary for their deployment success. Power control can be used as a platform for radio resource management and is important for channel fading as well as providing QoS to individual users. Xiao, Shroff and Chong review the developments of distributed power control and related resource management problems in cellular wireless systems. The discussion is concentrated on achieving high efficiency for a power-controlled system while preventing the system from failure. They then review power and rate control schemes proposed for wireless data, and present a framework for utility-based power control as a possible candidate for distributed power control of multimedia wireless systems. In the fifth paper, Arslan and Bottomley review commonly used approaches to channel estimation. This is necessary in adaptive receiver designs used in narrowband and wireless digital communication systems. They consider both time-invariant and time-varying channels in their discussion. They also provide a number of applications that will make use of this standard. On the other hand, Tepedelenliolu, Abdi, Giannakis and Kaveh talk about estimation of Doppler spread and signal strength in wireless systems. They concentrate on estimating the received signal strength, mobile velocity, and other related statistical channel parameters that apply to handoff and adaptive transmission. They provide comparison of the presented schemes based on their modeling and simulation results. Finally, Annamalai and Tellambura present a research paper discussing three new exponential-type bounds derived using the Cauchy–Schwarz bounding technique. They show that these new bounds are found to be tight and useful for a number of applications. They compare these bounds to other well-known exponential type bounds and prove that these perform at least comparable or tighter. We hope that you will enjoy reading this issue and welcome any comments to any of the four editors listed below. Again, we welcome all of you to contribute and encourage your colleagues and libraries to subscribe to this fine publication.

Vehicle-to-vehicle and vehicle-to-infrastructure wireless communications are currently under development to improve traffic efficiency and safety. The time-critical nature of road safety applications imposes the need to accurately dimension the operation and performance of wireless vehicular communication systems. Given that radio propagation modeling has been shown to importantly affect the performance of traditional mobile and wireless communication systems, this work investigates its impact on the dimensioning of traffic safety wireless vehicular communications by separately analyzing the contributions of pathloss, shadowing and fast fading.

Adaptive techniques play a key role in modern wireless communication systems. The concept of adaptation is emphasized in the Adaptation in Wireless Communications Series through a unified framework across all layers of the wireless protocol stack ranging from the physical layer to the application layer, and from cellular systems to next-generation wireless networks. Adaptation and Cross Layer Design in Wireless Networks is devoted to adaptation in the data link layer, network layer, and application layer. The book presents state-of-the-art adaptation techniques and methodologies, including cross-layer adaptation, joint signal processing, coding and networking, selfishness in mobile ad hoc networks, cooperative and opportunistic protocols, adaptation techniques for multimedia support, self organizing routing, and tunable security services. It presents several new theoretical paradigms and analytical findings which are supported with various simulation and experimental results. Adaptation in wireless communications is needed in order to achieve high capacity and ubiquitous communications. The current trend in wireless communication systems is to make adaptation dependent upon the state of the relevant parameters in all layers of the system. Focusing on simplified cross layer design approaches, this volume describes advanced techniques such as adaptive resource management, adaptive modulation and coding, 4G communications, QoS, diversity combining, and energy and mobility aware MAC protocols. The first volume in the series, Adaptive Signal Processing in Wireless Communications (cat no.46012) covers adaptive signal processing at the physical layer.

Solving channel equalization problem in communication systems is based on adaptive ltering algorithms. Today,Mobile Agents (MAs) with Recurrent Neural Networks (RNNs) can be also adopted for e ective interferencereduction in modern wireless communication systems (WCSs). In this paper MAs with RNNs are proposed asnovel computing algorithms for reducing interferences in WCSs performing an adaptive channel equalization.The method to provide it is so called MAs-RNNs. We perform the implementation of this new paradigm forinterferences reduction. Simulations results and evaluations demonstrates the e ectiveness of this approach andas better transmission performance in wireless communication network can be achieved by using the MAs-RNNsbased adaptive ltering algorithm.Keywords: Wireless communication systems, Mobile Agents, Recurrent Neural Networks, interferences reduc-tion, channel equalization 1. INTRODUCTION New challenges in modern communication is to conceive highly reliable and fast communication system deprivedfrom problems caused by multipath fading in wireless channels. A very important problem in data commu-nications is channel equalization. i.e., the removal of interferences introduced by linear or nonlinear messagecorrupting mechanisms. Thus the originally transmitted symbols can be recovered correctly at the receiver.New techniques to provide the optimal detection under bad channel estimation and solving the channel equal-ization must be developed and evaluated. To achieve fast and reliable wireless digital communication, as forinter-symbol interference (ISI), studies must concern adaptive equalization to minimize the communication errors

Physical layer security (PLS) in wireless communication systems has attracted extensive research attentions in recent years. Unlike cryptography-based methods applied in upper-layer in network, PLS methods are applied in physical layers and can provide information-theoretic security by utilizing the randomness of signals and wireless channels. In this survey, we provide a comprehensive review in the domain of physical layer authentication (PLA) in wireless communication systems, including the concepts, several key techniques of typical PLA architectures as well as future challenges and research trends in more sophisticated communication systems. The survey begins with an overview of the background and basic concepts of PLA, such as the general model of wireless security communication system, typical frameworks of key-based/less PLA systems, and the common attack models. We then discuss the major concerns and key techniques that are applied in PLA systems, where three types of authentication schemes are considered, i.e., the authentication based on channel information, radio-frequency and identity watermarks. Basic models and representative research results about key approaches and techniques applied to the authentication systems above are subsequently covered. Finally, the associated challenges and potential research trends of PLA in future communication systems are presented at the end of the survey paper.

In third generation wireless cellular communication systems, cell sizes are expected to become smaller in order to accommodate high user density and multimedia traffic. Resource allocation schemes will have to be flexible to handle heterogeneous traffic and be dynamically adapted to the time-varying channel and user mobility. We propose such a resource management strategy. We introduce the notion of a connection group, where a mobile user simultaneously connects to multiple base stations using multiple links. The number of base stations and which base station to connect to are functions of the time-varying channel, mobility, current bandwidth need, and quality of service requirement. Once a call is admitted into the network, the resource management strategy will allow the mobile to dynamically configure its connections in such a way to minimize call dropping probability, maximize signal quality, and increase channel resource utilization efficiency. The performance of the protocol is analyzed in terms of call blocking and dropping probabilities and channel resource utilization. Results show that the proposed resource management scheme can support multimedia traffic with low call blocking and dropping probabilities and high channel utilization efficiency.

For wireless cellular communication systems, one seeks a simple effective means of power control of signals associated with randomly dispersed users that are reusing a single channel in different cells. By effecting the lowest interference environment, in meeting a required minimum signal-to-interference ratio of rho per user, channel reuse is maximized. Distributed procedures for doing this are of special interest, since the centrally administered alternative requires added infrastructure, latency, and network vulnerability. Successful distributed powering entails guiding the evolution of the transmitted power level of each of the signals, using only focal measurements, so that eventually all users meet the rho requirement. The local per channel power measurements include that of the intended signal as well as the undesired interference from other users (plus receiver noise). For a certain simple distributed type of algorithm, whenever power settings exist for which all users meet the rho requirement, the authors demonstrate exponentially fast convergence to these settings.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Resource assignment without service priorities using channel quality information in LTE-advanced systems

The continuation of an active call is one of the most important feature of a wireless cellular communication system. Handover process enables a cellular system to provide such a facility by transferring an active call from one cell to another. Different approaches are proposed and applied in order to achieve better handover service. The key parameters that play vital role in handover process are received signal level and the received signal quality.