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In order to extend fair queueing algorithms to wireless networks, we propose a channel error and handoff compensation scheme. A compensation is performed by a compensation server and a priority swapping mechanism. The proposed compensation scheme provides a short-term fairness guarantee for an error-free session, long-term fairness guarantee for an erroneous session, fast handoff and traffic-specific quality of service control. Copyright 2002 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Summary Unmanned aerial vehicle operations are quickly gaining ground due to rapid global market penetration. While on one hand, novel technologies that bridge communication networks to aviation industry are yet to be explored, on the other hand, their development requires highly scalable systems to enable beyond visual line‐of‐sight missions. This requirement imposes a big bottleneck in terms of computation complexity. This paper presents a method for fast computation of multiple diffraction of radio waves over knife‐edge obstacles based on the Deygout technique and some offline computation steps, including a ground profile analysis. We prove that this algorithm is equivalent to the original Deygout algorithm for all non‐line‐of‐sight points, show heuristics confirming that it is mostly applicable in the line‐of‐sight case. The computational and memory complexity of our algorithm is approximately O(N)$$ \mathcal{O}\left(\sqrt{N}\right) $$, compared to O(N)$$ \mathcal{O}(N) $$ for the original Deygout algorithm. Finally we discuss how to apply the approach to the Epstein‐Peterson technique and the Giovanelli technique, and how to use it to compute clutter‐loss. [ABSTRACT FROM AUTHOR]

SUMMARY The paper proposes a cooperative group location (CGL) scheme to solve the ill-conditioned location problem in mobile communication networks, which means that the mobile terminal (MT) has no sufficient signal resources from the networks to uniquely localize itself. On the basis of rigid graph theory, the unique solvability of the CGL scheme is completely proved in the theory in this paper. In CGL, it is assumed that the different MTs can directly communicate with each other in a peer-to-peer manner and form a terminal group (TG), which is propelled by some distinct characteristics of next-generation wireless networks such as ubiquitous inter-net and inter-communicating, device-to-device connectivity, and so on. When each MT in a TG has no sufficient signal resources, the CGL scheme makes it possible to accurately locate all the MTs in the TG. Two CGL-based location algorithms-improved Taylor-series iteration location algorithm and search and positioning algorithm, are presented in this paper. The numerical simulation results indicate that the proposed algorithms have higher positioning accuracy over traditional geometric location methods in ill conditions. The CGL scheme can effectively enhance the robustness and precision of localization and provide a novel idea to the positioning of MTs in next-generation mobile communication networks. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY Recently, multiple cell types with overlapping coverage have been deployed simultaneously to increase cellular network capacity. Cross-tier interference is one of the key technical challenges in the use of this method. A simple and practical beamforming scheme assisted by locally positioned communication devices for the downlink of a multi-cell wireless hierarchical cell structure system is proposed in this paper to maximize the capacity of the embedded small cell and simultaneously ensure minimal impact on the performance of existing macrocells. The locally positioned communication devices can be implemented with low complexity and at low cost and can continuously provide helpful and accurate information to base stations for the proper configuration of geographical cell coverage, allowing neighboring cells to cooperate effectively with each other. Simulation results verify that the proposed scheme can provide a significant gain over conventional systems not using the proposed algorithm. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY In the past few years, we have seen a global flurry of the Internet in the rapid roll-out of multimedia-the commercial products such as PPlive, YouTube, and Skype have occupied a large portion of Internet bandwidth. One reason behind the continual growth of multimedia services is due to the increasingly deployed and offered broadband networks. Besides the traditional wired end users, Internet service providers (ISPs) are expected to provide multimedia services, especially video streaming, to wireless end users as well in that it allows ISPs to strengthen their competitiveness by offering these new services. However, the existing solutions to multimedia in wired networks cannot directly apply to wireless networks with lower bandwidth, higher latency, and higher burst error rate. Furthermore, these services could suffer from user's mobility and the heterogeneity caused by different wireless technologies (e.g. CDMA2000, WCDMA, TD-SCDMA, Wi-Fi, Long-Term Evolution (LTE), and WiMAX). This paper surveys several key issues of mobile multimedia, focusing on multirate multicast, scalable video coding (SVC), and QoS management. Besides, the opportunities as well as the challenges of providing multimedia services in the next generation wireless mobile systems-3GPP LTE-are investigated. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, the traffic performance of dynamic channel assignment (DCA) in cellular mobile system with hand-off is investigated. A traffic model for cellular system incorporating hand-off is established first. Under the framework of the model, a hand-off priority scheme is developed to reduce the forced termination of calls in progress. This paper analyses and derives the traffic performance bound for DCA strategies with hand-off by extending the maximum packing (MP) scheme to include the hand-off procedure. For practical implementation, a distributed DCA algorithm (DDCA) is also proposed. A non-priority scheme and the proposed priority scheme can be combined with either MP or DDCA. It is shown that the simulation results of DDCA scheme are comparable with the analytical bounds given by MP for both the non-prioritized case and prioritized case. A reasonable trade-off between the new call blocking probability and forced termination probability can be achieved by using the proposed prioritized scheme in DCA. Copyright © 2002 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper proposes a differentiated service (DiffServ)-based bandwidth-constrained network layer anycast routing for a mobile IPv6 network. The proposed algorithm comprises three steps: (1) When moving into a new foreign network, the mobile node (MN) chooses a feasible path to easily locate the nearest server that can serve it. To perform path selection, a multi-level list structure (MLLS) is defined and used to store the available bandwidth and hop count of a path. (2) An ingress extended edge router (E-ER) uses the multi-level list algorithm (MLLA) to examine the MLLS for selecting the feasible path with the smallest number of hops that satisfies the MN bandwidth request. (3) The E-ER uses a condition of path change (CPC) variable to determine whether it should optimize the route between itself and the server. Simulation results indicate that the proposed algorithm offers better performance than the existing related approaches in terms of the average running time, request blocking rate, and reducing the control overhead of the simulated network. Copyright © 2010 John Wiley & Sons, Ltd. A DiffServ-based bandwidth constrained anycast routing is used to select a new feasible path satisfying an MN QoS request when the MN changes its point of attachment. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

As over 70% of the earth's surface is covered by water, it is desirable to deploy underwater sensor networks (UWSNs) to support oceanic research. UWSNs use acoustic waves and are characterized by long and variable propagation delays, intermittent connectivity, limited bandwidth and low bit rates. Energy savings have always been the primary concern in wireless sensor network protocols; however, there are applications where the latency and throughput are prioritized over energy efficiency and are so significant that the application would not be able to satisfy its requirements without them. Although existing duty-cycle MAC protocols are power efficient, they introduce significant end-to-end delivery latency, provide poor throughput and are not suitable for the challenging environment of a UWSN. In this paper, we utilize CDMA as the underlying multiple access technique, due to its resilience to multi-path and Doppler's effects prevalent in underwater environments. We propose UW-MAC, a CDMA-based power-controlled medium access protocol that uses both transmitter-based and receiver-based CDMA inside a formed cluster, and uses a TDMA schedule to make the cluster heads communicate with the base station. Our MAC algorithm targets the latency and throughput needs in addition to its ability to increase the overall network lifetime. We discuss the design of UW-MAC, and provide a head-to-head comparison with other protocols through extensive simulations focusing on the performance in terms of latency, throughput, and energy consumption. Copyright © 2009 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, we introduce a network-based approach for access and interface selection (AIS) in the context of resource management in heterogeneous wireless environments (UMTS, WLAN and DVB-T). We focus on the optimization of resource utilization, while ensuring acceptable quality of service (QoS) provision to the end users. Our objective is to optimally manage the overall system resources and minimize the possibility of QoS handovers (non-mobility handovers). The adopted architecture applies to typical heterogeneous environments and network entities (Access Routers) are enhanced with extra functionalities. We propose an AIS algorithm that exploits the multihoming concept and globally manages network resources at both radio access and IP backbone networks. The algorithm can estimate near-optimal solutions in real time and we also introduce a novel triggering policy. We present simulation results of typical scenarios that demonstrate the advantages of our approach. System performance metrics, derived from the simulations, show minimum degradations in high load and congestion situations. Copyright © 2007 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Mobile Ad hoc NETwork (MANET) presents a constrained communication environment due to fundamental limitations of client resources, insufficient wireless bandwidth and users' frequent mobility. Caching of frequently accessed data in such environment is a potential technique that can improve the data access performance and availability. Co-operative caching, which allows the sharing and co-ordination of cached data among clients, can further explore the potential of the caching techniques. In this paper, we propose a novel scheme, called zone co-operative (ZC) for caching in MANETs. In ZC scheme, one-hop neighbours of a mobile client form a co-operative cache zone. For a data miss in the local cache, each client first searches the data in its zone before forwarding the request to the next client that lies along routing path towards server. As a part of cache management, cache admission control and value-based replacement policy are developed to improve the data accessibility and reduce the local cache miss ratio. An analytical study of ZC based on data popularity, node density and transmission range is also performed. Simulation experiments show that the ZC caching mechanism achieves significant improvements in cache hit ratio and average query latency in comparison with other caching strategies. Copyright © 2006 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, we consider the problem of assigning frequencies to mobile terminals in a cellular network. We show that an optimal solution can be obtained by solving a sequence of alternating linear and quadratic maximization programming problems. We address co-channel constraints and adopt as an objective function the maximization of potentially established calls. Our algorithm is fairly general, and does not depend on any special network structure. This study indicates that mathematical programming can be used as an efficient technique for solving the aforementioned problem. [ABSTRACT FROM AUTHOR]

We consider ad hoc wireless networks and the topology control problem defined as minimizing the amount of power needed to maintain connectivity. The issue boils down to selecting the optimum transmission power level at each node based on the position information of reachable nodes. Local decisions regarding the transmission power level induce a subgraph of the maximum powered graph Gmax in which edges represent direct reachability at maximum power. We propose a new algorithm for constructing minimum-energy path-preserving subgraphs of Gmax, i.e. ones minimizing the energy consumption between node pairs. Our algorithm involves a modification to the medium access control (MAC) layer. Its superiority over previous solutions, up to 60% improvement in sparse networks, demonstrates once again that strict protocol layering in wireless networks tends to be detrimental to performance. Copyright © 2005 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A set of three allocation algorithms is proposed and analysed. As opposed to a number of allocation algorithms, whose performance is greatly dependent on the traffic profile, these techniques are dynamically adaptable to the change of the traffic load, combining the features of dynamic channel allocation and fixed channel allocation, migrating smoothly from one to another technique to give the best performance in any circumstances. Although the proposed strategies assign the channels in a fully dynamic fashion, this is carried out in a disciplined way so that channels are packed into reuse groups and the reuse distance is kept to a minimum, increasing the reuse efficiency. Copyright © 1999 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]