Personal Wireless Communications

Preface

International Scientific Committee

Contents

In this work, we propose a new dynamic power management (DPM) technique for wireless sensor networks (WSNs) that selectively shutdowns the sensor node radio and other hardware components based on the application-level information. The DPM technique is modeled using the hybrid automata framework, which is lever-aged to represent different duty cycles, according to the application requirements. Both the application-level information and the application requirements determine the sensor node duty cycle and the trade-off between energy conservation and data delivery rate. We provide a comparison of our DPM technique using the main types of routing protocols to show the performance of our DPM technique in a sensor network modeled for a fire detection application. Simulation results reveal that our DPM technique can change the duty cycle of a node according to the data delivery quality required by the application and the need for communication, saving energy and, thus, extending the WSN lifetime.

Wireless sensor networks are not just stand-alone applications. Wireless sensors need to communicate to wired networks, where monitoring applications are usually connected to. This paper examines performance of SDMA in connections between wireless sensors and a wired network. SDMA is considered in the form of adaptive beamforming in the wired network base station. Interest is laid especially on connections with and without feedback. Performance is examined through simulations in a line-of-sight and a more realistic multi-path environments.

In wireless sensor networks, nodes generate important data that are of interest to the network users. These data have to be delivered reliably to the hub in the network which will then be disseminated to the network users. Routing protocols for such networks have to provide reliable delivery of data using minimal energy as nodes are energy-constrained. We propose EAR; a novel routing protocol that achieves reliability and energy efficiency in data delivery.

Coverage and connectivity are two fundamental problems in sensor networks and answer the questions about the quality of service that can be provided by a particular sensor network. We consider a new wireless sensor networks model that assumes each node can just connect with the other nodes that locate at the neighbor cells. And then we provide a mathematic analysis of the fundamental relationship among cells number, nodes number and the probability of coverage and connectivity. The analysis shows that the coverage is related to the number of sensor nodes and the size of the sensing area, the connectivity is also decided by the network topology besides the above two factors. The analysis results give underlying insights for treating coverage and connectivity in a unified framework.

Nowadays, the cross-layer design approach, is the most relevant concept in mobile ad-hoc networks which is adopted to solve several open issues. It aims to overcome MANET performance problems by allowing protocols belonging to different layers to cooperate and share network status informations while still maintaining separated layers. The central key of related research studies is what information can be shared and how it used in cross-layer architecture to provide QoS enhancement and enable an efficient resource utilization. In this work, we detail the most coupling features of introducing cross-layer models in mobile ad hoc networks. Then, we discuss the risks and the challenges facing this new architecture.

In the existing mobile ad hoc network (MANET) Quality-of-Service (QoS) routing/multicasting protocols, the methods of bandwidth calculation and allocation were proposed to determine routes with bandwidth guaranteed for QoS applications. As our observations, two bandwidth-violation problems will be incurred in the above protocols. In this paper, a heuristic algorithm is proposed to determine a feasible bandwidth-satisfied multicast tree without the two bandwidth-violation problems.

In this paper, we propose a new method to estimate the probability that link exists at t_o can be kept until t_o+∆t, where ∆t is decided by the actual application. Based on the link availability prediction, we can choose a reliable path for data transmission at t_o, which can also be used at t_o + ∆t. At last we test the performance of the protocol by simulation. The results show LAP-RRP can reduce broken times of the transmission path and the number of lost packets. LAP-RRP protocol improves network performance by reducing the influence on routing because of the mobility in MANET, especially when the number of nodes is large and the velocity of nodes is high.

A Mobile Ad hoc Network can be considered as an autonomous distributed system that consists of a set of identical mobile nodes that move arbitrarily and use wireless links to communicate with other nodes that reside within its transmission range. In our work, we analyze the performance of the original IEEE 802.11b wireless local area networks and we present an efficient load-balancing scheme in MAC for support QoS over MANET. Simulation results aimed to highlight the capability of our algorithm to reduce packet lose rate and to increase throughput in the MAC layer are provided.

A cross layer routing protocol is proposed for MANETs in this paper, which is called Bandwidth-Efficient Cross Layer Probability Routing (BECLPR). BECLPR differentiates between the send bandwidth and the receive bandwidth of the node. Based on the available send/receive bandwidth range provided by the MAC layer, a probability model is defined in BECLPR which is called Available-Bandwidth-Aware Probability Model of the Node (ABAPMN). By that each node processes the route request message with a given probability on its ABAPMN in the route discovery procedure, BECLPR probabilistically distributes the loads among the nodes according to the available send/receive bandwidth resources in MANETs. Also the output queue length of the node on the path is considered in searching for a path. Simulation results show that BECLPR outperforms the Ad hoc On-demand Distance Vector routing (AODV) in terms of the packet delivery ratio and routing overhead. BECLPR has lower end-to-end delay than AODV when the network load is not too high.

An effective Medium Access Control for communications in wireless Ad hoc networks should be able to support both broadcast and point-to-point communications paradigms. The ADHOC MAC protocol, recently proposed within the European Commission funded CarTALK2000 project, seems to match these requirements. As a matter of fact, it allows the exchange of connectivity information among wireless terminals which can be usefully exploited to devise both broadcast and point-to-point services. In this paper we evaluate through simulation the efficiency of the protocol in a mixed traffic scenario where broadcast and point-to-point communications coexist. An adaptive bandwidth allocation strategy is proposed to share the resources between both services in a dynamic situation. The capability of the protocol to establish parallel point-to-point data communications and the corresponding improvement in the point-to-point efficiency is also evaluated

Ad-hoc networks that use the IEEE 802.11 MAC layer suffer from severe performance issues because nodes compete to access the wireless channel. In such a context, the network topology has a great influence on the overall network performance. In this paper, we present a connectivity aware QoS routing framework that takes routing decisions with regards to the local characteristics of the network topology. The advantages of the approach is to rely solely on observations made by each node locally and applies with existing MAC layers.

Medium Access Control (MAC) for Ad-hoc networks has been a major concern of both academia and industry for many years. Even though the dominant MAC for ad-hoc networks is CSMA/CA, it leads to a number of disadvantages like high overhead, increased access delay, high jitter and limited QoS capabilities. TDMA appears as a promising solution for overcoming these issues, but the application of TDMA in ad-hoc networks leads to the known NP complete Broadcast Scheduling Problem (BSP). This paper presents a new polynomial algorithm that can provide a suboptimal solution the BSP. The efficiency of the new algorithm is evaluated in terms of complexity, delay, throughput and fairness, and is compared with other solutions

In this paper, we present a new leader election algorithm for mobile ad hoc networks, in order to handle arbitrary topology changes and group self-organizing or self-stabilising. Our proposed leader election algorithm ensures that eventually nodes of a communication system network can form a group. Within this group start nodes trigger the leader election, in order to organize nodes in one hierarchical level with leader election. We also simulate the algorithm in mobile ad hoc network settings. Through our simulation study, we point out several important issues that can significantly influence performance of such a protocol for ad hoc networks, such as choice of signalling, broadcast nature of wireless medium, etc. The simulation study shows that, furthermore the proposed algorithm auto-organize mobile nodes; it brings the group to support QoS, in several operating conditions.

In this paper, hierarchical dynamic source routing (HDSR) protocol is introduced for heterogeneous mobile ad hoc networks architecture. In this network architecture, there are two tiers: Forwarding nodes (FN) and mobile nodes (MN). FNs route the packets and MNs host the applications. Dynamic source routing (DSR) protocol is modified and optimized for mobile multi-tiered ad hoc network architecture. The new routing protocol, HDSR, separates route discovery (route requests and replies), and packet forwarding functionalities. Those two functionalities are distributed into two node types, where only route requests and replies are functional in MNs when they are source or destination, and both route discovery and packet forwarding are functional in FNs. HDSR combined with hierarchical architecture has lower routing overhead and shorter route discovery delays, because in HDSR there are smaller number of route reply and route request messages than in regular DSR. HDSR is implemented by network simulator (Network Simulator-2 of University of California). It was shown via computer simulations that HDSR improves average end-to-end delay per packet, network throughput and packet delivery ratio in wireless ad hoc networks compare to regular DSR.

Mobile Ad Hoc Networks totally depend on cooperation. Each node is involved in forwarding data. Unfortunately, it is not obvious why a node should cooperate: forwarding data costs battery power and bandwidth. Research in this area is focused on approaches making stations behave more cooperatively. In contrast to this, the issue whether those approaches really improve the network performance is not well understood. In this work we present a general model for analyzing the effect of cooperation approaches in mobile ad hoc networks. To characterize the level of cooperation we use several classes of nodes, which forward data with class-specific probabilities. We show that cooperation approaches can improve the network performance in certain circumstances.

Ad hoc networks are spontaneous networks of mobile nodes which use wireless communications. The nodes must collaborate to route and forward data packets from a source to a destination. We consider multihops wireless access networks which are ad hoc networks connected to the Internet via Access Points (AP). A terminal can send and receive data packets to and from the Internet. To achieve this goal, we propose here a micro-mobility management solution. The solution uses a virtual backbone to centralize information and to limit the overhead. The proposition mixes the reactive and the proactive approaches to propose a trade-off between the delay and the overhead. In upload, each node has a default proactive route toward the AP introducing no latency. In download, the AP initiates a reactive localization to find a route to the destination inside the ad hoc area, reducing the overhead. A solution of paging with several AP and a solution of power-energy saving are also proposed.

Security research in mobile ad hoc networks(MANETs) has been receiving increasing attention due to its evident importance in practical deployments. The main progress achieved so far is the protection of the critical Route Discovery component of on-demand routing protocols. In this paper, we identify that Location Update is the key component for geographic routing. To focus on securing the basic local location update, we propose three schemes in this paper with a detailed discussion.

In this paper, we tray to reduce the degree of QoS degradation in IEEE 802.11 wireless ad-hoc network while enhancing at the same time the estimation of the quality of service of the networks. We shall present PEDCF: Predictive Enhanced Service Differentiation methods for forecasting resources to meet the QoS requirements for real-time service support based on AutoRegressive Moving Average processes: ARMA. These processes provide a range of models, stationary, that adequately represent the time Contention Window (CW) variations. The results obtained (in terms of throughputs and end-to-end delays) show that the PEDCF protocol, based on ARMA processes, performs better than conventional EDCF.

This paper presents a new transmission power control protocol, CSNE-PC that addresses the energy inefficiency of basic power control protocols (BPC) in which RTS and CTS packets are exchanged at full power while data and acknowledgement transmissions are carried out at low power. This is accomplished by reducing hidden data collisions which is responsible for energy inefficiency in BPC. CSNE-PC implements a mechanism for inference of low-power data transmissions in the presence of power control. A node measures the duration of its carrier-sense activities and analyses it for detecting 802.11 CTS packets. Upon detecting a CTS packet, the node sets or extends its NAV and enters into a silence mode for a pre-determined packet duration. This enables transmission power control without incurring additional data collisions as described above. Evaluation of CSNE-PC through simulation demonstrates that under sustainable loading conditions, reduction in combined transmit and receive energy can be as high as 38%, and that is while retaining the throughput and delay characteristics of the regular 802.11 protocol.

Chaos engineering for mobile communications is an emerging field of research. Chaos-based modulation schemes such as Chaos Shift Keying (CSK) and Differential Chaos Shift Keying (DCSK) have been proposed as alternatives to conventional digital communication systems. This paper introduces a way to apply CSK in broadband wireless access systems such as IEEE 802.11a. As well as this, it provides in brief the advantages and disadvantages of such a system. Results concerning spectrum are provided with the use of a link-level simulator with basic functions.

The performance of energy-saving protocols for IEEE 802.11 wireless local area networks was analysed under time-correlated error conditions. Using OPNET, simulations were performed to compare the performance of the infrastructure power saving mode of IEEE 802.11 (PCF-PS) with our proprietary protocol, pointer controlled slot allocation and resynchronisation protocol (PCSAR). The results demonstrate a significant improvement in energy efficiency without significant reduction in performance when using PCSAR. For a wireless network consisting of an access point and 8 power saving stations, energy consumption was up to 28 % lower with PCSAR compared to PCF-PS. The results also show that PCSAR offers significantly reduced uplink access delay over PCF-PS, while modestly improving uplink throughput.

In this paper, we propose COMPASS, a new decentralized access control architecture for modern WLANs. As traditional centralized access control systems like AAA do not scale well, we propose the use of P2P technologies for the distribution of management data directly between the deployed WLAN access points. Our system COMPASS does not require any additional equipment or central entities. Using auto-organization and fault recovery mechanisms of modern P2P systems, it is robust and easier to maintain. Standard 802.1X mechanisms on the user link guarantee compatibility to the existing user equipment.

The IEEE 802.11 wireless LAN (WLAN) is the most widely used standard nowadays for wireless LAN technology. However, the current standard does not provide QoS support for multimedia communications. Thus, a large number of enhancements to the standard are being proposed. This paper introduces some of the most relevant schemes: the Priority-Based Distributed Mechanisms. We also present the upcoming IEEE 802.11e (EDCA) standard being introduced. The IEEE 802.11e standard is a proposal defining the mechanisms for wireless LANs aiming to provide QoS support to multimedia communications. In this paper, we carry out a comparative study of Priority-Based Distributed Mechanisms and the 802.11e (EDCA) upcoming standard, when supporting different services, such as voice, video, best-effort and background traffic.

There is a growing demand for the transmission of multimedia applications over wireless computer networks. The aim of this study was to analyse the effects of minimum Contention Window (CW_min) on Quality of Service in IEEE 802.11 MAC protocol. This study was carried out using ns-2 simulation software. The analysis was based on four Variable Bit Rate (VBR) connections with different packet sizes, distributed randomly in the same Basic Service Set (BSS). It was demonstrated that poorly selected values of CW_min result in considerable network performance degradations. Moreover, the CW_min value for achieving optimum QoS proved to be different. Based on this work, an intelligent method for determining the CW_min size to achieve optimum QoS has been proposed.

Bluetooth is a suitable technology to support soft real-time applications like multimedia streams at the Personal Area Network (PAN) level. In this paper, we evaluate the worst-case deadline failure probability (WCDFP) of Bluetooth packets under co-channel interference as a way to provide statistical QoS guarantees.

This article presents the implementation of a real time platform needed for critical wireless communications. The objective of this work is to evaluate real time system temporal behaviors based on RTAI and the Bluetooth (WPAN) real time communications management for control/command applications (control/command of remote mobile robots). We present a necessary aspect for the optimized operations (interruptions, management of the clock) of the asynchronous ports in the real time environment. Then the different asynchronous Bluetooth communication channels are presented and implemented in order to evaluate their behavior and performance.

Following FCC approval of Ultra-Wide Band (UWB) radio rules for commercial applications in 2002, a UWB radio physical layer standard is currently under development within the IEEE 802 LAN/MAN Standard Committee. Although the UWB transmitter and UWB band are spelled out by the FCC, neither UWB signal forms nor modulation schemes are defined by the regulations [1]. This paper illustrates two types of impulse UWB radio modulation systems and their simulation performance. They are direct sequence UWB (DS-UWB) and time modulated (TM- UWB) or so called time hopping UWB (TH-UWB). Unique ways of coding and positioning the impulses, as in Transmitted-Reference Delay (TRD) modulation and Pulse-Position Modulation (PPM), can result in the simple UWB radio architectures. Systems of TRD for DS-UWB and PPM for TH-UWB are simulated under the same data and under the same AWGN channel conditions. TRD-DS-UWB system presents superior performance over PPM-TH-UWB system, which is shown in the comparison chart of the paper. The simulation was verified with ideal calculated performance for TRD modulation. The UWB applications are also discussed.

This paper presents a global solution for QoS improvement in 802.11 Wireless LANs. The proposed approach is based on Medium Access Control (MAC) enhancements, taking into account informations from both the physical and the network layers for packets differenciation scheduling at the MAC level.

In this paper, a novel analytical cross-layer design framework for dynamic resource management of wireless networks is proposed. First, dynamic bandwidth and time resource allocation policies for a single-user under fading channels that maximize capacity are derived. The analysis is then extended to multi-user environments, where the resource allocation is jointly optimized across both physical and data link layers. A closed-form expression of a QoS measure, mean delay in this case, is derived as a function of layer 2 traffic, multiple access contention from other users, and allocated data-rates at the physical layer. This mean delay expression is then used to efficiently allocate physical layer resources. We also study the effects of various contention mitigation policies on network capacity and average latency under optimum resource allocation strategies.

In this paper, we present an analytical model to study the impact of changing soft handoff coverage on the system performance for cellular CDMA systems. In the model, we assume a cell is in hexagon shape with two parameters representing the soft handoff region between the inner and the outer cell. By assuming that the new call generation rate per unit area is uniformly distributed over the service area and by adjusting the soft handoff region parameters, we can calculate the blocking and the dropping probabilities of the systems using the Markov model.

This paper provides the analysis of the Least Mean Square (LMS) and the Recursive Least Square (RLS) adaptive algorithms performance for adaptive CDMA receivers in slowly time varying communication channels in the presence of multi-path. We confirm that neither the LMS algorithm nor the RLS algorithm has a complete monopoly over good performance in a non-stationary environment. Rather, one or the other of these two algorithms is preferred, depending on the environmental conditions that are prevalent. We show that the LMS algorithm provides a good tracking if speed of channel change is slow, but LMS stability criteria depend on signal statistics (and so, on channel conditions). The RLS convergence and stability criteria do not depend of signal statistics, but the RLS involves memory and does not explicitly recognize time varying nature of the channel. Presented simulation results confirm the theoretical analysis.

The next generation wireless and mobile networks need to support a wide range of multimedia applications, such as voice, data, image and video. The crucial issue is to provide QoS guarantees for arriving multiclass traffic. Thus, the need for efficient and bandwidth reservation scheme is compulsory. In this paper, we propose a preemptive priority reservation handoff scheme that categorizes the service calls into four categories according to the QoS guarantees. The system is modelled using a multidimensional Markov chain and a numerical analysis is presented to estimate several performance measurements, in terms of blocking probability of ongoing calls, forced termination probability, and average transmission delay. The simulation confirms the correctness of the analytic model and the good performance of the proposed scheme.

In this paper, the impact of the correlation on the performance of multiple-cell DS-CDMA cellular systems over correlated fading channels is investigated. A new closed-form formula for the joint probability density function (joint pdf) of the diversity combiner with arbitrary correlation coefficients in terms of the generalized Laguerre polynomial and the new expressions of average bit-error rate (BER) for the DS-CDMA system are given in this paper. The results demonstrate that the BER is significantly dependent on the correlation characteristic of diversity branching for multiple-cell environments.

The scheme of real time streaming video is one of the newcomers in wireless data communication, raising a number of new requirements in both telecommunication and data communication systems. This scheme applies when the user is experiencing real time multimedia content. This paper has as main target to study the performance of video transmission over the third generation cellular networks. In particular, we examine the performance of UMTS Dedicated Channels (DCHs) for real time MPEG-4 video transmission in Downlink direction. Finally, we examine if real time video transmission in conjunction with Internet traffic is applicable in UMTS radio interface.

In this paper the Parallel Index Clusters (PIC), a clustered application layer architecture is presented. Based on the performed simulation and analysis it is proposed as an appropriate content sharing solution in decentralized wireless/cellular peer-to-peer environments. In earlier work a basic review of maintenance aspects has been performed [2]. We have also proposed and compared cluster topology alternatives. Here we perform the optimization of these topologies based on the performance metrics: minimal traffic and load balance. The optimal cluster size is determined as a function of metrics in various traffic scenarios.

HSDPA (High Speed Downlink Packet Access) is a very important stage in the evolution of UMTS. It allows downlink transmission with peak rates theoretically up to 14.4 Mbps. To enable this, new features and mechanisms were introduced in UMTS physical and MAC layers in release 5 of the standard. The goal of this paper is to analyse some of these features in MAC and suggest solutions to enhance HSDPA performance. We propose a two stage HSDPA scheduler in MAC-hs, consisting of Proportional Fair and dynamically adjusted Weighted Round Robin scheduling algorithms. We also present some configuration guidelines to optimize HSDPA performance and radio resource utilization.

Many of the admission control strategies for cellular data networks proposed in the literature allow the network operator to use different policies, depending on the network load, the number of users from each quality of service class, etc. Each policy is applied in a certain region, the regions being separated by thresholds. Those approaches suffer from a lack of flexibility: when the operating conditions change, the values for the thresholds have to be re-calculated. Our work supports flexible and adaptable network operator policies, overcoming the drawbacks of the existing algorithms through a fuzzy logic based solution.

Mobile telephony has been for many years the most popular application supported by mobile systems such as the Global System for Mobile communications (GSM). Recently, the use of mobile data applications has gained popularity. Different protocols and technologies are in place today to provide wireless and mobility communications in various environments.

General Packet Radio Service (GPRS) is part of the evolution path towards 3G. So there are many publications to study main parameters that affect the performance of GPRS and to propose techniques that enhance the overall performance.

In this paper, the performance and quality of service (QoS) management in the General Packet Radio Service (GPRS) network are examined. To achieve this, simulation results of GPRS performance such as End-to-End delay and throughput are produced under different conditions with a GPRS simulation based on the Optimized Network Engineering Tool (OPNET) simulation package.

We examine the effects of the Bit Error Rate (BER) on the signaling plane in GPRS network and how it affects the network performance. We also study the quality of service sensitivity to the change of the packet inter arrival distribution function which is one of the major factors of representing the source applications beside the file size.

Although Mobile IPv6 allows maintaining transport layer connections alive when an IPv6 node roams to different access networks, certain enabling mechanisms are needed for it to work in large scale network scenarios, including, most notably, issues with Mobile IPv6 bootstrapping and firewall traversal. This paper tries to address these problems by extending the IETF PANA and NSIS protocols to form an extensible framework for wide deployment of a secure, light-weight mobility service in operational IPv6 environments.

The handover delay for the basic Mobile IPv6 (MIPv6) is too long to meet the requirement of real-time services. Therefore, IETF proposed a tunnel-based Fast Handover Protocol for MIPv6 (FMIPv6). We implement the tunnel-based FMIPv6 in Wireless LANs (WLANs) through the combination of using the Link Up trigger (L2-LU) and the Fast Router Advertisement (F-RA). In this paper, we analyze the performance of handovers with respect to the basic MIPv6 and our tunnel-based FMIPv6 implementation in WLANs. In our implementation, we apply a mechanism called Access Router’s Information Cache (ARIC) to optimize the handover. Experiment results prove that our implementation can effectively improve the handover performance.

The network mobility (NEMO) basic support protocol, developed by the IETF, provides uninterrupted Internet connectivity to the communicating nodes of mobile networks. This protocol makes network movements transparent to the mobile nodes. However, delays in data delivery and higher overheads are likely to occur because of sub-optimal routing and multiple encapsulation of data packets. To resolve this problem, we propose an extended Mobile IPv6-type route optimization scheme for mobile networks. The proposed scheme is simple and easy to deploy, as it requires only slight modification of the NEMO basic support protocol at local entities such as the mobile router and mobile nodes of the mobile network, leaving entities in the core or in other administrative domains untouched. This scheme enables a correspondent node to forward packets directly to the mobile network without any tunneling, thus improving the packet delivery efficiency and reducing end-to-end packet delay.

Latency during handoffs affects the service quality of real-time applications. Mobile IP (MIP) presents the standard mobility management protocol. However, Mobile IP is not adequate for delay sensitive applications. Mobile IP Fast Authentication protocol (MIFA) is proposed to avoid the problems of Mobile IP and to match the requirements of real-time applications. In this paper we present an analytical model to evaluate the performance of MIFA. Our performance study shows that the handoff latency of MIFA is independent of the distance between the current FA and the HA. Thus, MIFA highly reduces the handoff latency for most cases. MIFA clearly outperforms Mobile IP (MIP) with respect to the handoff latency and the number of packets dropped due to handoffs.

this paper presents the integration of protocol hierarchical mobile IPv6 with multiprotocol label switching (M-MPLS) and the protocol of quality of service Diffserv in mobility scenarios. We use for it simulation TCP traffic. The goal and integrated framework is to facilitate efficient and reliable network operation and to provide optimal Quality of Services (QoS).

In recent years, we have witnessed the proliferation of commercial multimedia services being offered over wireless mobile networks. The limited bandwidth and higher data loss and error ratio of mobile network air interface make the monitoring of end-to-end service quality experienced by mobile users a critical element in service management. Equally critical is the ability to quickly diagnose the root causes when service performance degrades. Few studies have been reported on monitoring service and traffic performance of wireless mobile networks, partly due to the difficulty in accessing or installing third party monitoring applications on mobile devices. Though many challenges remain, the increasing openness of mobile device platforms has opened the door for service quality monitoring and diagnosis. This paper proposes an agent-based framework for mobile multimedia service quality monitoring and diagnosis. Monitoring and diagnostic agents can be dynamically dispatched, installed, and activated on end user mobile devices. The proposed framework effectively turns thousands of mobile devices into service performance monitoring stations. It also provides an accurate, efficient way for end-to-end mobile service quality monitoring and diagnosis.

The dramatic increase in the number of mobile subscribers has put a significant strain on resource and service provisioning current cellular networks in particular in terms of multimedia and high-data rate service provision. Hybrid wireless networks, which is a novel scalable and adaptive wireless network architecture utilizing a mixture of cellular and ad hoc multi-hop routing, facilitates cellular network design with small cell systems without having to wire a large number of base stations into a core network. In this paper, a self-management architecture for base stations in hybrid networks based on autonomic computing is presented. Neural Network training and Self-learning within the IBM autonomic element are introduced in order to enable self-configuration and self-optimisation at the radio resource and routing layer. Simulation results indicate the advantages of our proposed approach in utilizing wireless radio resource, optimizing system performance and reducing the administration complexity.

In this paper, we introduce WebBee, a client-proxy architecture that combines a web scraping proxy with a Java client to make a platform-independent gateway between small mobile devices, such as mobile phones, and the vast information available on the World Wide Web. The key technology behind WebBee is a web scraping engine that executes “scraping scripts,” a domain-specific scripting language we designed for the purpose of fetching web pages and selectively extracting information from them. By transmitting to and displaying only this extracted information on the client device, WebBee gives mobile devices with small displays and low network bandwidth clean and quick access to web content customarily designed for desktop browsers.

Our surrounding environment is changing day after day. Almost in an unperceivable way, even though steadily, more and more little computing and communicating devices are populating our homes, workplaces, clothes, streets or cars. All these devices need a common architecture to communicate, self-organise and cooperate, being one of such architectures Universal Plug and Play (UPnP). Wireless UPnP is the appropriate technology for mobile devices that roam around, creating and partaking in ad-hoc networks emerging everywhere. But UPnP still uses an interaction model with the environment not suitable for present users’ needs that require more intelligence around them, as stated in the concept of Ambient Intelligence (AmI). Issuing commands continually such as open the door, turn on the light, or play the movie using some kind of universal controller such as a PDA or mobile phone, only relieves the user from having physical contact with the device, but not from completely free him from directing and coordinating the action. In this paper we propose the use of the WebProfiles model to extend UPnP capabilities enabling wireless UPnP devices to act in response to user’s preferences, adapting the environment without being explicitly commanded, and so, getting closer to the new, more subtle interaction model with the activated world.

This paper presents new methods for Subscriber Identification Module (SIM) card communication using Internet protocols. These methods enable the handset user to access the SIM card as a network node, for example by using a Web browser on the phone. More importantly, the methods enable the SIM to establish reliable and secure end-to-end connection with any remote Internet server and to secure Internet online transactions for mobile commerce.

Current middleware systems provide convenient access mechanisms to services for wire bound stationary terminals, but not for all special needs of mobile terminals. Dynamic adaptation of services to varying network quality and support for heterogenous terminals are not integrated, but must be configured manually. Service persistence and session continuation are great challenges in the presence of mobility across network borders and service adaptation. In this paper, we present an architecture that inserts a node between mobile clients and wired service providers. This node bridges between the service providers and the clients. Thus, it acts as a gateway between the different access networks and we call it Middlegate (MG).

This paper presents a channel preemption model for multimedia traffic in mobile wireless networks. In the proposed model, a mobile call is distinguishable with four parameters, call type, traffic class, channel requirement, and preemption ratio. Different classes of multimedia traffic possess different priority levels. To effectively reduce dropping probability, high-priority handoff calls are allowed to fully or partially preempt low-priority ongoing calls when the mobile network becomes congested. Performance measures, including the dropping probability of handoff calls, the call-interruption probability of fully preempted calls, the bandwidth reduction ratio of partially preempted calls, and the preemption cost paid for supporting high-priority handoff calls are investigated through a multi-dimensional Markov model.

The handoff makes the primary contribution towards the latency of mobile IP. Lots of fast handoff issues are already being touched in IETF Mobile IP Working Group. Unfortunately, there is no solution that can be used in the current wireless LANs directly because the link-layer handoff triggers are needed by all of those fast handoff solutions. However, those triggers are not supported by the current wireless LANs standards. In this paper, we propose a nonuniform-detection-based handoff scheme that can provide fast handoff ability to the mobile nodes of wireless LANs with no changes to the hardware and standards. In our scheme, MAC addresses of access points are compared at nonuniform intervals. That enables the mobile node know whether the handoff occurs rapidly. By comparing with the existent solutions, we show that the scheme can reduce the latency of mobile IP handoff and the cost of handoff detection for wireless LANs.

Mobile users and devices need to discover and share a growing range of information. Users may want to discover, for example, the existence and locations of local networks, network services and applications, and information contents. Emerging mobile devices may want to know, for example, the existence of neighboring networks and information needed to access these networks. This could reduce handoff delay and the energy expended on attempting to connect to the wrong networks. Existing service discovery frameworks cannot easily support the discovery of dynamic information (e.g., traffic conditions), information regarding neighboring networks, or other location-based information. This paper uses a new approach for real time collection, discovery, and sharing of user and network information, which we refer to as Autonomous Collaborative Discovery (ACD). It analyzes the information reporting and retrieval costs of the proposed methods.

Cellular SCTP (cSCTP) and Mobile SCTP (mSCTP) are two extended SCTP protocols which all support handover management. The existing cSCTP/mSCTP-based IP mobility solutions all must use third party methods to realize location management. In the high-mobility networks applied these schemes, some problems will emerge, e.g. (1) MN’s load is relatively heavy. (2) More network resources are used. (3) May result in handover blind zone and handover delay. In this paper, we propose a novel cSCTP-based scheme-EasyMN, it is especially fit for high-mobility network. EasyMN has some notable advantages, e.g. (1) It reduces the load of MN and abrogates location registration mechanism. (2) It avoids handover blind zone and handover delay. (3) It needs not to use third party location management methods. (4) Its location management load is in proportion to the busyness degree of calls, and is irrelative to the number of handover.

One of the disadvantages of using OFDM is the larger peak to averaged power ratio (PAPR) of its time domain signal. The larger PAPR signal would course the fatal degradation of bit error rate performance (BER) due to the inter-modulation noise occurring in the non-linear channel. In this paper, we propose the PAPR reduction method for the OFDM signal by using the dummy sub-carriers of which phases are optimized on the basis of the time-frequency domain swapping algorithm and flipping technique. The proposed method can achieve the better PAPR performance and BER performance in the non-linear channel with less complexity of processing at the transmission side. This paper presents various computer simulation results to verify the effectiveness of proposed method as comparing with the conventional methods.

In this paper we study the performance gain achieved by introducing dynamic subcarrier scheduling schemes to OFDM systems in the presence of heterogeneous traffic streams. Dynamic subcarrier scheduling copes with channel state variation by dynamically assigning different subcarriers to terminals, e.g. in the downlink of a cellular system. In addition to the channel state variations, also the arrival of data is highly variable for most applications. This calls for schemes that exploit both sources of variation. In the homogeneous traffic scenario, dynamic subcarrier scheduling in combination with semantic queueing mechanisms can significantly increase the capacity of an OFDM cell. In a heterogeneous traffic scenario, however, these mechanisms do not simply carry over. Therefore, in this work we study first the performance increase achieved for heterogeneous flows by purely switching from static to dynamic subcarrier scheduling and then introduce a semantic traffic management scheme that improves the achieved performance further by sacrificing the transmission of semantically unimportant video packets for important video packets and for packets related to HTTP.

A verification for the accurate calculation of the power spectral density of the H-Ternary line code is carried out in this paper. The power spectral density is evaluated through the use of a Matlab simulation model. The model considers the generation of a P-N sequence and encodes it to the H-ternary code. The FFT techniques are used to determine the power spectral density of the line code. The results obtained from the simulation model reveal a total agreement with that of the theoretical model. Both results show a favourable spectrum of the proposed line code compared with other line codes.

A number of modern wireless systems use modulation schemes like CPFSK, GMSK and DPSK, where the information to be transmitted is exclusively coded in the phase change of the RF-signal. Thus the detection of the received data can be performed by using only the zero crossings of the hard-limited IF-signal. With respect to implementation costs and power consumption this is a very attractive receiver concept. A superior performance compared to conventional zero crossing detectors can be obtained by applying methods of pattern recognition for the signal detection. A straight forward implementation of such a detector however is considerably more complex with respect to the requirements for the digital signal processing. In this contribution it will be shown that the complexity can be drastically reduced by combining the pattern classification scheme with the viterbi algorithm. No performance losses have to be taken into account when using this more efficient implementation.