Wireless Mobile Communication Networks Research Articles

An accelerating handover process scheme for IEEE 802.16j multi-hop relay networks

IEEE 802.16j multi-hop relay network systems provide the mobile wireless communication environment. In such network systems, the handover scanning procedure allows a mobile station (MS) to obtain the information about the handover target base stations (BSs) or relay stations (RSs). The network systems need more time to negotiate the association parameters and to handle scanning the BSs and the RSs when the number of BS and RS increases. It results in more overhead for the handover scanning procedure. In order to accelerate the handover process and reduce the transmission interruption, efficient handover scanning procedure schemes and corresponding algorithms must be developed and designed. A novel relative angle computing algorithm is proposed in this article to accelerate the handover process by taking into account the moving behavior of the MS, and the distances among the MS, the RS, and the BS. The main idea of this algorithm is to reduce the management information overhead and to estimate the potential moving path of the MS in the wireless mobile communication networks. By using the proposed scheme, we eliminate the unnecessary associations and scanning intervals, and reduce the handover scanning procedure efficiently. Simulation result demonstrate the superior performance of our proposed scheme and its ability to strike the appropriate performance in the handover overhead and the message delay for IEEE 802.16j multi-hop relay network systems.

Joint cooperative analog network coding and OFDM system for wireless communication networks

In wireless mobile communication networks, network coding and cooperation are the promising techniques to increase the spectrum utilisation efficiency. OFDM is also one of the most efficient modulation techniques to deal with multipath fading channel distortions. In this paper, a scheme of joint analog network coding and OFDM for cooperative communication systems is proposed, and the scheme suggests using network coding to improve the system spectral efficiency, and using OFDM to cope with channel distortion. The analysis of frame error probability for the proposed scheme is presented.

PATH LOSS PREDICTION USING FUZZY INFERENCE SYSTEM AND ELLIPSOIDAL RULES

It is well known as the prediction of radio wave path loss in urban environment plays a key role in order to correctly plan wireless systems and mobile communication networks. To obtain more flexible prediction models able to give accurate results, in recent years Soft computing Techniques has been exploited. In this study, a novel approach based on ellipsoidal fuzzy inference system EFIS is investigated. Results compared with those provided by the Okumura Hata model and the standard Fuzzy Inference System approach (FIS) show superior performances of the EFIS approach.

A Campus Safety Monitoring System Based on Ad-Hoc Network

This paper introduces a campus safety monitoring system based on wireless mobile communication network. Backbone network of the system is an ad-hoc network based on Opportunity Driven Multiple Access (ODMA) multi-hop relaying protocol, which has the characteristics of wireless relaying, quickly and flexible network formation, dynamic topology etc. The system has the functions of image real-time transmission, the patrol car mobile camera shooting and video signal mobile transmission, and static and mobile wireless Internet access etc.

Flexible Data Dissemination Strategy For Effective Cache Consistency In Mobile Wireless Communication Networks

In mobile wireless communication network, caching data items at the mobile clients is important to reduce the data access delay. However, efficient cache invalidation strategies are used to ensure the consistency between the data in the cache of mobile clients and at the database server. Servers use invalidation reports (IRs) to inform the mobile clients about data item updates. This paper proposes and implements a multicast based strategy to maintain cache consistency in mobile environment using AVI as the cache invalidation scheme. The proposed algorithm is outlined as follows – To resolve a query, the mobile client searches its cache to check if its data is valid. If yes, then query is answered, otherwise the client queries the DTA (Dynamic Transmitting Agent) for latest updates and the query is answered. If DTA doesn’t have the latest updates, it gets it from the server. So, the main idea here is that DTA will be multicasting updates to the clients and hence the clients need not uplink to the server individually, thus preserving the network bandwidth. The scenario of simulation is developed in Java. The results demonstrate that the traffic generated in the proposed multicast model is simplified and it also retains cache consistency when compared to the existing methods that used broadcast strategy.

MERGING LINK-LEVEL AVAILABILITY BASED ON FADED AND NOISY CHANNEL CHARACTERTIZTION

System level performance evolution of mobile wireless communication networks has been addressed by only resource insufficiency where as the effect an unreliable wireless channel has largely been ignored. Wireless communication systems are subject to short and long fading of channel. Signal is likely to suffer from the damaging effects of channel fading. In this paper the system level performance of mobile wireless networks is studied where the effect and characterization of “Average Network Availability Time” due to shadowing and fading channel model used to calculate the interruption probability when a desired signal and interference undergo short fading and shadowing simultaneously.

Optimal Base Station Clustering for a Mobile Communication Network Design

This paper considers an optimal base station clustering problem for designing a mobile (wireless) communication network. For a given network with a set of nodes (base stations), the problem is to optimally partition the set of nodes into subsets (each called a cluster) such that the associated inter-cluster traffic is minimized under certain topological constraints and cluster capacity constraints. In the problem analysis, the problem is formulated as an integer programming problem. The integer programming problem is then transformed into a binary integer programming problem, for which the associated linear programming relaxation is solved in a column generation approach assisted by a branch-and-bound procedure. For the column generation, both a heuristic algorithm and a valid inequality approach are exploited. Various numerical examples are solved to evaluate the effectiveness of the LP (Linear Programming) based branch-and-bound algorithm.

Extremum-Seeking Control in Constrained Source Tracing With Nonholonomic Vehicles

This paper proposes an extremum-seeking approach for source tracing problems with vehicles subjected to minimum turning radius and nonholonomic constraints. The admissible area for the vehicles is confined within boundary constraints. Extremum-seeking control with sliding mode is utilized for direction finding, and variable structure control is designed to address the constraints on vehicle kinematics and the accessible area. The controller enforces the vehicle to track an optimal trajectory determined by both the motion of the source and the boundary constraints. We present stability and performance analysis for the approach and establish an ultimate bound on the tracking error. A representative simulation example in the context of mobile wireless communication network illustrates the design of the extremum-seeking controller and demonstrates its performance in tracking the optimal trajectory.

A Hybrid Resource Allocation Strategy with Queuing in Wireless Mobile Communication Networks

The main objective of third and future wireless mobile communication networks is to provide services efficiently to the mobile users in all environments. In wireless mobile Communication the channel allocation and quality of service are the major factors and important issues to decide the system performance. Here in our work a Hybrid Channel Allocation(HCA)strategy for channel allocation and queuing technique applied to Hybrid Channel Allocation strategy for Quality of Service(QoS) provisioning are implemented. The proposed HCA strategy considers new calls in Fixed Channel Allocation (FCA) method and handoff calls in Dynamic Channel Allocation (DCA) method to reduce the call blocking and call dropping probabilities. The application of queuing technique applied to HCA strategy increases the efficiency of the cellular system performance especially in micro and pico cellular environments and effectively utilize the available allocated radio spectrum. The performance shows the decrease in call blocking and dropping and an increased number of users in the available channels.

System-Level Analysis of Mobile Cellular Networks Considering Link Unreliability

Traditionally, system-level performance evaluation of mobile wireless communication networks has been addressed by only considering resource insufficiency, whereas the effect of an unreliable wireless channel has largely been ignored because of the complexity that its inclusion entails. To fill this void, a general analytical model for the system-level performance evaluation of mobile wireless networks taking into account both resource insufficiency and link unreliability is proposed in this paper. The effect of link unreliability is captured through the appropriate probabilistic characterization of the ldquounencumbered call-interruption time.rdquo Additionally, useful functional relationships between the call-interruption processes of the proposed analytical model and some system-level parameters that can easily be obtained from statistics collected at base stations (BSs) are derived. For the sake of generality, the involved time variables (i.e., cell dwell time, unencumbered call-interruption time, and channel holding time) are considered generally distributed. Then, general and easily computable mathematical expressions for many useful performance metrics under more realistic considerations are obtained. The analytical model proposed here is able to provide new and important insights into the dependence of system performance on link unreliability. Such understanding of this teletraffic engineering issue is vital for planning, designing, dimensioning, and optimizing mobile cellular networks for present and future wireless communication systems beyond the third generation.

Performance analysis of wireless mobile networks with queueing priority and guard channels

AbstractThe blocking probability of originating calls and forced termination probability of handoff calls are important criteria in performance evaluation of integrated wireless mobile communication networks. In this paper, we model call traffic in a single cell in an integrated voice/data wireless mobile network by a finite buffer queueing system with queueing priority and guard channels. We categorize calls into three types of service classes: originating voice calls, handoff voice calls and data calls. The arrival streams of calls are mutually independent Poisson processes, and channel holding times are exponentially distributed with different means. We describe the behavior of the system by a three‐dimensional continuous‐time Markov process and present the explicit expression for steady‐state distribution of queue lengths using a recursive approach. Furthermore, we calculate the blocking, forced termination probabilities and derive the Laplace–Stieltjes transform of the stationary distribution of actual waiting times and their arbitrary kth moment. Finally, we give some numerical results and discuss the optimization problem for the number of guard channels.

Technostress under different organizational environments: An empirical investigation

Today’s pervasive information and communications technologies (ICTs) enable us to get connected almost anywhere at anytime. ICTs such as the Internet, the advanced wireless technologies and mobile communications networks are becoming increasingly indispensable in many aspects of business and everyday life. But to keep up with the fast advancing pace of the new ICTs, employees have to constantly renew their technical skills as well as enduring pressure from a more complex system and higher expectations for productivity. This often leads to ICT related technostress experienced by employees in many organizations. Studies have found technostress to have significant negative impact on employee productivity. Based on large-scale survey responses Chinese employees, this paper investigates the effects of different organizational environment settings on employee technostress levels. The results show that employees from more centralized companies often perceive more technostress. In addition, in organizations that are both highly centralized and highly innovative, the overall technostress level is the highest. On the other hand, in organizations with low centralization and low innovation, technostress is the lowest. This research will provide a foundation for organizations to understand and alleviate technostress, thus improving employee performance.

Performance Analysis of 3G Communication Network

In this project, third generation (3G) technologies research had been carried out to design and optimization conditions for 3G network. The 3G wireless mobile communication networks are growing at an ever faster rate, and this is likely to continue in the foreseeable future. Some services such as e-mail, web browsing etc allow the transition of the network from circuit switched to packet switched operation, resulting in increased overall network performance. Higher reliability, better coverage and services, higher capacity, mobility management, and wireless multimedia are all parts of the network performance. Throughput and spectral efficiency are fundamental parameters in capacity planning for 3G cellular network deployments. This project investigates also the downlink (DL) and uplink (UL) throughput and spectral efficiency performance of the standard Universal Mobile Telecommunications system (UMTS) system for different scenarios of user and different technologies. Power consumption comparison for different mobile technology is also discussed. The analysis can significantly help system engineers to obtain crucial performance characteristics of 3G network. At the end of the paper, coverage area of 3G from one of the mobile network in Malaysia is presented.

Survivability and performance optimization of mobile wireless communication networks in the event of base station failure

In this paper, we investigate the survivability of mobile wireless communication networks in the event of base station (BS) failure. A survivable network is modeled as a mathematical optimization problem in which the objective is to minimize the total amount of blocked traffic. We apply Lagrangean relaxation as a solution approach and analyze the experiment results in terms of the blocking rate, service rate, and CPU time. The results show that the total call blocking rate (CBR) is much less sensitive to the call blocking probability (CBP) threshold of each BS when the load is light, rather than heavy; therefore, the more traffic loaded, the less the service rate will vary. BS recovery is much more important when the network load is light. However, the BS recovery ratio (BSRR), which is a key factor in reducing the blocking rate for a small number of BSs, is more important when a system is heavily loaded. The proposed model provides network survivability subject to available resources. The model also fits capacity expansion requirements by locating mobile/portable BSs in the places they are most needed.

Fast ray-tracing technique for electromagnetic field prediction in mobile communications

Ray-optical propagation models are often used for the prediction of the field strength (and delay spread) in wireless mobile communication networks. However, these models suffer from long computation times. For large areas in urban or indoor scenarios, the computation times are in the range of hours which is too long for the planning of mobile radio networks. In this paper, we present a fast algorithm based on a ray-tracing technique with scalable approximation accuracy for field strength prediction in cellular mobile network planning together with a preprocessing of the geographical database. Automatic network design methods perform a huge number of field strength estimations and, therefore, require a fast and accurate approximation. However, common prediction techniques either give only rough estimations or are too complex for fast evaluation. The proposed new ray-tracing technique obtains its speedup by taking advantage of the topological information inherent in the used triangulation data structure of the investigated terrain. The applicability of the fast ray-tracing technique is demonstrated for a single transmitter scenario.

An adaptive-transmission protocol for frequency-hop wireless communication networks

An energy-efficient adaptive-transmission protocol for mobile frequency-hop spread-spectrum wireless communication networks is described and evaluated. The purpose of the protocol is to permit each...

Nonuniform phase-shift-key modulation for multimedia multicast transmission in mobile wireless networks

It is a common requirement in a mobile wireless communication network that a radio must be capable of simultaneously transmitting a message to two or more neighbors in the network. Some of the intended recipients may be more capable than others in the sense that their communication links from the transmitter have less interference, fading, or attenuation. Because it is desirable that a multicast or broadcast transmission be received successfully by all radios for which it is intended, the usual approach is to limit the transmission rate to that which can be demodulated by the least capable among these radios. Nonuniform nonbinary phase-shift-key (PSK) signal constellations can be designed to increase the throughput of multicast transmissions by delivering additional information to more-capable receivers along with the multicast message. This additional throughput can be employed to transmit multimedia messages (e.g., voice and data) to the more-capable receivers. In this paper, we determine the error probabilities for coherent demodulation of nonuniform PSK signals and noncoherent demodulation of nonuniform differential PSK signals. Because the PSK constellations have a constant envelope, they are better for use in mobile wireless communication networks than the constellations based on quadrature-amplitude modulation that have been proposed in previous publications.

Teletraffic performance of mobile radio networks with hierarchical cells and overflow

Wireless mobile networks, comprising a hierarchical layer of cells, use the cell layering to provide alternate routing for calls. This paper proposes a model for multilayered wireless mobile communications networks that provides a unified treatment of overflow to account for intra- and interlayer overflow. This takes account of the inherent overlap between cells in the same layer and between layers, and hence the prospect of controlling the overflow to achieve a tradeoff between new call and handover performance. The mobility of users within the layers is included in the model, and this allows handover performance to be estimated. Network performance is evaluated in terms of caller-perceived performance by calculating the probability of call failure using a Markov chain model of call progress. An example is presented that provides a comparison of the network performance for a range of overflow policies. The main contribution of this paper is the development of an analytic method that treats overflow in a unified manner. This allows the approximate performance of overflow strategies that balance the need to maintain calls in progress with the desire to accept more new calls to be evaluated for large networks.