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In this paper, we introduce a new power spectral efficiency (PSE) metric, to quantify the spectral efficiency and the total required power to cover a certain area with a predefined received signal quality. This metric offers the possibility to find the optimal transmission power in each base station to cover the total given area with the minimum total consumed power. We start by deriving the closed-form expression of the maximum transmission range under Rayleigh fading environment. Based on the maximum transmission range, we define and derive the average affected area, the total consumed power and the average ergodic capacity. Then, we introduce the PSE expression, to quantify the power spectral utilization efficiency. After that, we evaluate the new metric for cellular network with 3-cell frequency reuse cluster (3-CFRC), without inter-cell interference (ICI), and the network with 1-cell frequency reuse cluster (1-CFRC) and ICI. Through mathematical analysis and numerical examples, we show that the PSE metric provides a new perspective on the design and optimization of wireless transmissions, especially on the transmission power selection. Qatar National Research Fund Scopus

Measurements for GSM cellular phone networks (the 1800 MHz as well as the 900 MHz bands) in different areas of Irbid city, Jordan, were carried out, for over a year and under varying weather conditions, by the authors. To find a radiofrequency propagation model that can correctly predict the propagation in this environment, various path loss models are compared with the measurements. These models include: Lee, COST-231 Hata, COST-231 WI, and Egli models. The results show that the COST-231 Hata model is the most accurate model whereas Lee model is the least accurate model for Irbid city. To enhance the accuracy of the least accurate model for this area, i.e., Lee model, this paper suggests a path loss model based on optimizing Lee model using the swarm intelligence optimization (PSO) technique. It is worth noting that optimization of Lee model for Irbid measurements using the least squares method produced the same results as the PSO optimization; therefore, only the PSO results will be presented here. The accuracy of the optimized Lee model is verified by comparison with measurements in other locations in Irbid. Furthermore, measurements made in Amman city in Jordan confirm the usefulness and validity of the measurements and predictions of Irbid city. The root mean square error (RMSE) between the measured and predicted values for the proposed model is significantly improved by up to 37 dB compared with Lee model.

Capacity has always been a major concern in wireless networks. This letter studies the impact of mobility on the overall system capacity in wireless cellular networks. In this letter, we present a simple system model which we developed to capture the inherent relationships among system capacity, new call blocking probability, handoff dropping probability, call terminating probability, and bandwidth utilization rate. We investigate the complex relationship between mobility and capacity-related parameters. Through simulation, we demonstrate that mobility has a significant impact on capacity and is reversely proportional to the bandwidth reserved for handoff traffic.

In wireless cellular networks, previous researches on admission control policies and resource allocation algorithm considered the QoS (Quality of Service) in terms of CDP (Call Dropping Probability) and CBP (Call Blocking Probability). However, since the QoS was considered only within a predetermined cell capacity, the results indicated a serious overload problem of systems not guaranteeing both CDP and CBP constraints, especially in the hotspot cell. That is why a close interrelationship between CDP, CBP and cell capacity exists. Thus, it is indispensable to consider optimal cell capacity guaranteeing multiple QoS (CDP and CBP) at the time of initial cell planning for networks deployment. In this paper, we will suggest a distributed determination scheme of optimal cell capacity guaranteeing both CDP and CBP from a long-term perspective for initial cell planning. The cell-provisioning scheme is performed by using both the two-dimensional continuous-time Markov chain and an iterative method called the Gauss-Seidel method. Finally, numerical and simulation results will demonstrate that our scheme successfully determines an optimal cell capacity guaranteeing both CDP and CBP constraints for initial cell planning.

In wireless cellular networks, in order to ensure that ongoing calls are not dropped while the users roam among cells, handoff calls may be admitted with a higher priority as compared to new calls. One way to improve system performance of cellular networks is to use efficient handover schemes when users move between cells. In this paper, a new dynamic scheme, called Dynamic Channel Reservation (DCR) is proposed and evaluated to improve the utilization of wireless network resources. The required GoS of handoff calls are guaranteed. Simulation results show that the proposed scheme improves handoff calls blocking probability in expense of an acceptable blocking probability of new calls.

Caused by Non-Line-Of-Sight (NLOS) propagation effect, the non-symmetric contamination of measured Time Of Arrival (TOA) data leads to high inaccuracies of the conventional TOA based mobile location techniques. Robust position estimation method based on bootstrapping M-estimation and Huber estimator are proposed to mitigate the effects of NLOS propagation on the location error. Simulation results show the improvement over traditional Least-Square (LS) algorithm on location accuracy under different channel environments.

To effectively use limited resources in wireless cellular networks it is necessary to predict exactly the amount of resources required by handoff calls at a future time. In this paper we propose a method which predicts the amount of resources needed by handoff calls more accurately than the existing method based on Wiener processes. The existing method uses the current demands to predict future demands. Although this method is much simpler than using traffic information from neighbor cells, its prediction error increases as time elapses, leading to waste of wireless resources. By using an exponential parameter to decrease the magnitude of error over time, we show in simulation how to outperform the existing method in resource utilization as well as in prediction of resource demands.

This paper presents a new decentralized dynamic channel allocation scheme which uses a 'clustering' concept to allocate channels efficiently. Simulation results show that the proposed scheme performs better than fixed channel assignment and some other dynamic channel allocation schemes under low and moderate traffic load conditions.

Deregistration due to the departures of mobile users from their current visiting registration area may cause significant traffic in the wireless cellular networks. In this paper, we propose a hierarchical implicit deregistration scheme with forced registration in third-generation wireless cellular networks to reduce the remote/international roaming signaling traffic when home-location registers (HLRs), gateway-location registers (GLRs), and the visitor-location registers (VLRs) form a three-level database hierarchy. In this scheme, if a mobile phone arrives and the GLR/VLR is full, a random record is deleted and the reclaimed storage is reassigned to the new arriving mobile phone. When a call arrives and the callee's record is missing in the GLR/VLR, forced registration is executed to restore the GLR/VLR record before the call-setup operation proceeds. An analytic model is proposed to carry out the performance evaluation for the proposed scheme. Our results show that the proposed scheme not only reduces the local deregistration traffic between the GLR and the VLR, but also reduces the remote/international deregistration traffic between the HLR and the GLR, especially when the ratio of the cost of the remote/international traffic between GLR and HLR to the cost of local traffic between the VLR and the GLR is high.

In this paper, we propose an adaptive quality of service (QoS) design approach via resource reservation and rate adaptation to support multimedia over wireless cellular networks. Three contributions of this work are: (a) an adaptive QoS model that seeks to provide QoS assurances within bounds for each packet flow and to make advance resource reservation in order to support seamless mobility, (b) a revenue-based resource adaptation design that seeks to maximize network revenue while satisfying the QoS requirements, and (c) a resource reservation protocol that supports both application-initiated resource reservation and network-initiated resource adaptation. Our initial implementation and measurements confirm the effectiveness of the proposed design.

L’émergence de nouvelles applications et de nouveaux services (tels que les applications multimédias, la voix-sur-IP, la télévision-sur-IP, la vidéo-sur-demande, etc.) et le besoin croissant de mobilité des utilisateurs entrainent une demande de bande passante de plus en plus croissante et une difficulté dans sa gestion dans les réseaux cellulaires sans fil (WCNs), causant une dégradation de la qualité de service. Ainsi, dans cette thèse, nous nous intéressons à la gestion des ressources, plus précisément à la bande passante, dans les WCNs. Dans une première partie de la thèse, nous nous concentrons sur la prédiction de la mobilité des utilisateurs des WCNs. Dans ce contexte, nous proposons un modèle de prédiction de la mobilité, relativement précis qui permet de prédire la destination finale ou intermédiaire et, par la suite, les chemins des utilisateurs mobiles vers leur destination prédite. Ce modèle se base sur : (a) les habitudes de l’utilisateur en terme de déplacements (filtrées selon le type de jour et le moment de la journée) ; (b) le déplacement courant de l’utilisateur ; (c) la connaissance de l’utilisateur ; (d) la direction vers une destination estimée ; et (e) la structure spatiale de la zone de déplacement. Les résultats de simulation montrent que ce modèle donne une précision largement meilleure aux approches existantes. Dans la deuxième partie de cette thèse, nous nous intéressons au contrôle d’admission et à la gestion de la bande passante dans les WCNs. En effet, nous proposons une approche de gestion de la bande passante comprenant : (1) une approche d’estimation du temps de transfert intercellulaire prenant en compte la densité de la zone de déplacement en terme d’utilisateurs, les caractéristiques de mobilité des utilisateurs et les feux tricolores ; (2) une approche d’estimation de la bande passante disponible à l’avance dans les cellules prenant en compte les exigences en bande passante et la durée de vie des sessions en cours ; et (3) une approche de réservation passive de bande passante dans les cellules qui seront visitées pour les sessions en cours et de contrôle d’admission des demandes de nouvelles sessions prenant en compte la mobilité des utilisateurs et le comportement des cellules. Les résultats de simulation indiquent que cette approche réduit largement les ruptures abruptes de sessions en cours, offre un taux de refus de nouvelles demandes de connexion acceptable et un taux élevé d’utilisation de la bande passante. Dans la troisième partie de la thèse, nous nous penchons sur la principale limite de la première et deuxième parties de la thèse, à savoir l’évolutivité (selon le nombre d’utilisateurs) et proposons une plateforme qui intègre des modèles de prédiction de mobilité avec des modèles de prédiction de la bande passante disponible. En effet, dans les deux parties précédentes de la thèse, les prédictions de la mobilité sont effectuées pour chaque utilisateur. Ainsi, pour rendre notre proposition de plateforme évolutive, nous proposons des modèles de prédiction de mobilité par groupe d’utilisateurs en nous basant sur : (a) les profils des utilisateurs (c’est-à-dire leur préférence en termes de caractéristiques de route) ; (b) l’état du trafic routier et le comportement des utilisateurs ; et (c) la structure spatiale de la zone de déplacement. Les résultats de simulation montrent que la plateforme proposée améliore la performance du réseau comparée aux plateformes existantes qui proposent des modèles de prédiction de la mobilité par groupe d’utilisateurs pour la réservation de bande passante., The emergence of new applications and services (e.g., multimedia applications, voice over IP and IPTV) and the growing need for mobility of users cause more and more growth of bandwidth demand and a difficulty of its management in Wireless Cellular Networks (WCNs). In this thesis, we are interested in resources management, specifically the bandwidth, in WCNs. In the first part of the thesis, we study the user mobility prediction that is one of key to guarantee efficient management of available bandwidth. In this context, we propose a relatively accurate mobility prediction model that allows predicting final or intermediate destinations and subsequently mobility paths of mobile users to reach these predicted destinations. This model takes into account (a) user’s habits in terms of movements (filtered according to the type of day and the time of the day); (b) user's current movement; (c) user’s contextual knowledge; (d) direction from current location to estimated destination; and (e) spatial conceptual maps. Simulation results show that the proposed model provides good accuracy compared to existing models in the literature. In the second part of the thesis, we focus on call admission control and bandwidth management in WCNs. Indeed, we propose an efficient bandwidth utilization scheme that consists of three schemes: (1) handoff time estimation scheme that considers navigation zone density in term of users, users’ mobility characteristics and traffic light scheduling; (2) available bandwidth estimation scheme that estimates bandwidth available in the cells that considers required bandwidth and lifetime of ongoing sessions; and (3) passive bandwidth reservation scheme that passively reserves bandwidth in cells expected to be visited by ongoing sessions and call admission control scheme for new call requests that considers the behavior of an individual user and the behavior of cells. Simulation results show that the proposed scheme reduces considerably the handoff call dropping rate while maintaining acceptable new call blocking rate and provides high bandwidth utilization rate. In the third part of the thesis, we focus on the main limitation of the first and second part of the thesis which is the scalability (with the number of users) and propose a framework, together with schemes, that integrates mobility prediction models with bandwidth availability prediction models. Indeed, in the two first contributions of the thesis, mobility prediction schemes process individual user requests. Thus, to make the proposed framework scalable, we propose group-based mobility prediction schemes that predict mobility for a group of users (not only for a single user) based on users’ profiles (i.e., their preference in terms of road characteristics), state of road traffic and users behaviors on roads and spatial conceptual maps. Simulation results show that the proposed framework improves the network performance compared to existing schemes which propose aggregate mobility prediction bandwidth reservation models.

Conference of 2014 IEEE Wireless Communications and Networking Conference, WCNC 2014 ; Conference Date: 6 April 2014 Through 9 April 2014; Conference Code:109204; International audience; In wireless cellular networks, multiple scenarios involve the communication between devices located in the same vicinity. These links can be offloaded to a device to device (D2D) underlay which is controlled by the cellular infrastructure. Such an option alleviates the load on the base stations and saves spectrum resources for downlink connections. In this paper, we investigate the impact of D2D communications on the capacity of a cellular network from two directions: Average link capacity and coverage. We present a stochastic geometry based framework which captures both cellular and device to device links. Based on this framework, we quantify the enhancements offered by D2D underlay in terms of system coverage, average link capacity and spectrum usage.

Cloud radio-access network (CRAN) is a wireless cellular network architecture in which the base-stations are connected to a cloud-computing based central processor with digital backhaul links. In this setting, the base-stations can be thought of as relays between the central processor and the user terminals. This paper considers the downlink of a cloud radio-access network with finite-capacity backhaul links. We model the overall network as a broadcast-relay channel, and propose a hybrid compression and message-sharing strategy for the downlink transmission. This paper further proposes numerical techniques for optimizing the quantization noise level in the compression part of the hybrid precoding scheme. We compare the system-level performance of the proposed scheme with the pure compression and the pure message sharing schemes to show the benefit of the hybrid strategy for the downlink CRAN.

In this paper heterogeneous wireless cellular networks based on two-tier architecture consisting of macrocells and femtocells are considered. Methods of femtocells deployment and management are explored in order to determine their effects on performance of wireless cellular networks. Thus, network performance parameters are described and analytically calculated for different two-tier network architectures. A specific approach is presented in the paper, where calculations of the network performance parameters are supported with some of the results obtained using an appropriate simulation tool. In such a manner, energy efficiency of the considered two-tier network architectures is studied by introducing a number of so called green metrics. It is clearly shown that significant energy efficiency, as well as throughput, improvements can be achieved by adopting heterogeneous architecture for wireless cellular networks.

This chapter tackles the challenging task of QoS evaluation and improvement in cellular networks. Initially, the authors provide a classification based on four criteria of the queuing models used in the literature. In a second step, an analysis of technologies shows that combining queue management and scheduling mechanisms may lead to improvement in QoS. Hence, the authors propose design of queuing models that meet all the classification criteria, with the goal of improving the various QoS parameters required by the different classes of flows (real time and non-real time) transmitted to an end user in a cell. These models have been mathematically and numerically analyzed, and their impact on end-to-end QoS in a mobile cellular network has been proved.

In this short review paper we summarise the emerging challenges in the field of participatory sensing for the self-organisation of the next generation of wireless cellular networks. We identify the potential of participatory sensing in enabling the self-organisation, deployment optimisation and radio resource management of wireless cellular networks. We also highlight how this approach can meet the future goals for the next generation of cellular system in terms of infrastructure sharing, management of multiple radio access techniques, flexible usage of spectrum and efficient management of very small data cells.

We present a model for soft, hand-off in wireless cellular networks. In such networks, due to overlapping cells, hand-offs are not instantaneous and multiple channels may be occupied by a single mobile for a non-zero freeze time period. We provide a mathematical model of wireless cellular networks with soft hand-offs. We examine different performance measures and show that freeze time may have a major impact on the system performance if the mobility rate is not negligible. Both exact and approximate formulations are given. Different fixed-point approximation methods are used to reduce the complexity of the exact solution. Various performance measures such as new and hand-off blocking and probability of a call dropout are carefully examined.

International audience; We give numerically tractable, explicit integral expressions for the distribution of the signal-to-interference-and-noise-ratio (SINR) experienced by a typical user in the down-link channel from the k-th strongest base stations of a cellular network modelled by Poisson point process on the plane. Our signal propagation-loss model comprises of a power-law path-loss function with arbitrarily distributed shadowing, independent across all base stations, with and without Rayleigh fading. Our results are valid in the whole domain of SINR, in particular for SINR

An almost ubiquitous assumption made in the stochastic-analytic approach to study of the quality of user-service in cellular networks is Poisson distribution of base stations, often completed by some specific assumption regarding the distribution of the fading (e.g. Rayleigh). The former (Poisson) assumption is usually (vaguely) justified in the context of cellular networks, by various irregularities in the real placement of base stations, which ideally should form a lattice (e.g. hexagonal) pattern. In the first part of this paper we provide a different and rigorous argument justifying the Poisson assumption under sufficiently strong lognormal shadowing observed in the network, in the evaluation of a natural class of the typical-user service-characteristics (including path-loss, interference, signal-to-interference ratio, spectral efficiency). Namely, we present a Poisson-convergence result for a broad range of stationary (including lattice) networks subject to log-normal shadowing of increasing variance. We show also for the Poisson model that the distribution of all these typical-user service characteristics does not depend on the particular form of the additional fading distribution. Our approach involves a mapping of 2D network model to 1D image of it “perceived” by the typical user. For this image we prove our Poisson convergence result and the invariance of the Poisson limit with respect to the distribution of the additional shadowing or fading. Moreover, in the second part of the paper we present some new results for Poisson model allowing one to calculate the distribution function of the SINR in its whole domain. We use them to study and optimize the mean energy efficiency in cellular networks.

In cellular networks, while the motivation behind all basic channel assignment strategies is the better utilization of the available frequency spectrum with the consequent reduction of the call blocking probability in each cell, very few of them deal with the problem of non-uniform traffic demand in different cells which may lead to a gross imbalance in the system performance. Mobile users in hot cells (the cells with heavy traffic loads) may suffer from low throughput due to the load imbalance problem. In this paper, we propose a load balancing scheme where a borrowed channel can be used in borrower as well as in lender cell simultaneously. To cope with the interference introduced by channel borrowing, cell tiers with different radii are used. Simulation results shows that the scheme can effectively balance the load among cells of a cellular cluster.

International audience; Shadowing is believed to degrade the quality of service (QoS) in wireless cellular networks. Assuming log-normal shadowing, and studying mobile's path-loss with respect to the serving base station (BS) and the corresponding interference factor (the ratio of the sum of the path-gains form interfering BS's to the path-gain from the serving BS), which are two key ingredients of the analysis and design of the cellular networks, we discovered a more subtle reality. We observe, as commonly expected, that a strong variance of the shadowing increases the mean path-loss with respect to the serving BS, which in consequence, may compromise QoS. However, in some cases, an increase of the variance of the shadowing can significantly reduce the mean interference factor and, in consequence, improve some QoS metrics in interference limited systems, provided the handover policy selects the BS with the smallest path loss as the serving one. We exemplify this phenomenon, similar to stochastic resonance and related to the ''single big jump principle'' of the heavy-tailed log-nornal distribution, studying the blocking probability in regular, hexagonal networks in a semi-analytic manner, using a spatial version of the Erlang's loss formula combined with Kaufman-Roberts algorithm. More detailed probabilistic analysis explains that increasing variance of the log-normal shadowing amplifies the ratio between the strongest signal and all other signals thus reducing the interference. The above observations might shed new light, in particular on the design of indoor communication scenarios.

There is great interest in considering the energy efficiency aspect of wireless cellular networks. When a wireless cellular network is powered by the smart grid, only considering energy efficiency in the cellular network is not enough. In this paper, we consider not only energy-efficient communications but also the dynamics of the smart grid in operating green wireless cellular networks. We formulate the system as a two-level Stackelberg game. A backward induction method is used to analyze the proposed scheme. we prove that the Stackelberg equilibrium (SE) of the proposed game exists and is unique. An iteration algorithm is proposed to obtain the SE. Simulation results show that the smart grid has a significant impact on green wireless cellular networks, and our proposed scheme can significantly reduce operational expenditure and CO2 emissions in green wireless cellular networks.

In this paper, we consider the fair resource allocation problem for device-to-device (D2D) communications in Orthogonal Frequency Division Multiple Access (OFDMA)-based wireless cellular networks. In particular, we propose a two-phase solution approach where resource allocation for cellular downlink and uplink flows with max-min fairness is performed in the first phase and resource allocation for D2D flows with rate protection for cellular flows is conducted in the second phase. We present both optimal formulations and low-complexity algorithms to solve the corresponding problems in the two phases. We also analyze the complexity of both solutions. Finally, we present numerical results to demonstrate the efficacy of the proposed algorithms in exploiting the spatial spectrum opportunities for D2D communications.

The importance of wireless cellular communication in our daily lives has grown considerably in the last decade. Besides using cell phones for voice communication, we routinely use them to access the internet, conduct monetary transactions, send text messages and query a lot of useful information regarding the location of specific places of interest. The use of mobile devices in our day-to-day communication raises many unresolved security issues. In this paper we identify the possible attacks on the wireless cellular network architecture and propose some appropriate countermeasures. Several attacks can be prevented in order to preserve security in wireless cellular communication.

This paper introduces a solution to provide selective access in cellular wireless networks. The current best known solution for preventing users from service access in a cellular network is to deploy signal jammers. However, due to several shortcomings associated to the use of signal jammers, their deployment is facing several technical and legal issues. The proposed solution of this paper is based on deployment of small cells that allows for flexible access mechanism and full control of the operators. Coverage optimisation is one of the most important aspects that assures successful deployment of the solution whilst minimizing the service disruption to other users. Hence, depending on the application scenario and deployment priorities, a method of coverage optimisation is introduced. The overall solution is evaluated through accurate ray tracing simulations for Hynes convention centre in Boston for which the validity of the ray tracing simulation model is verified through measurements.

In this paper, we are introducing a time-based location prediction technique for wireless cellular networks. This technique is based on a two dimensional sequence mining algorithm. We have taken concepts of data partitioning methods and modified SPADE algorithm (Sequential PAttern Discovery using Equivalence classes), which has been implemented over a mining model known as mining mobile sequential patterns, and called Dynamic MobileSPADE algorithm. This algorithm mines for mobile sequential patterns based on dynamic-length item sets. In mining for mobile sequential patterns in a mobile environment, we use base stations ID data from a dataset constructed by the reality mining project at the MIT. Experiments were conducted to study and evaluate the performance of the proposed techniques. The experimental results show that the proposed technique is promising and it can be used effectively to predict future locations of mobile users with high accuracy using the generated mobile sequential patterns.

This paper examines the shared relay architecture for the wireless cellular network, where instead of deploying multiple separate relays within each cell sector, a single relay with multiple antennas is placed at the cell edge and is shared by multiple sectors. The advantage of shared relaying is that the joint processing of signals at the relay enables the mitigation of intercell interference. To maximize the benefit of shared relaying, the resource allocation and the scheduling of users among adjacent cell sectors need to be optimized jointly. Based on this motivation, this paper formulates a network utility maximization problem for the shared relay system that considers the practical wireless backhaul constraint of matching the relay-to-user rate demand with the base-station-to-relay rate supply using a set of pricing variables. In addition, zero-forcing beamforming is used at the shared relay to separate users spatially; multiple users are scheduled in the frequency domain to maximize frequency reuse. A heuristic but efficient scheduling and resource allocation algorithm is proposed accordingly. System-level simulations quantify the effectiveness of the proposed approach, and show that the incorporation of the shared relay can improve the overall network performance and in particular significantly increase the throughput of cell edge users as compared to separate relaying.

In wireless cellular network with heterogeneous services, providing guaranteed Quality of Service (QoS) poses a great challenge due to the scarce radio bandwidth. Often researchers in this field have tried to reduce the handoff call dropping probabilities (HCDP) in a cell at the sacrifice of increasing the new call blocking probabilities (NCBP). In this paper we propose a call admission control (CAC) scheme for WiMAX networks to achieve a fair trade-off between NCBP and HCDP. Numerical results showed that the proposed CAC scheme shows improvement in NCBP without affecting HCDP.

We develop an analytical approach to the performance analysis and optimization of wireless cellular networks for which different types of calls are prioritized based on a channel reservation scheme. We assume that the channel occupancy time differs for new and handover calls. We obtain simple formulas for calculating quality of service (QoS) metrics and solve some problems related to finding the optimal values of guard channels as well as present the results of numerical experiments.

Location management is one of the most challenging issues in future wireless mobile networks. In this paper, from the viewpoint of fundamental principles underlying location management schemes regardless of network types, we review and analyze a variety of existing location management schemes which have been reported for wireless cellular networks and Mobile IP-based networks, and derive common key conceptual ideas, their main design goals and common performance considerations on them, which can provide a useful guidance for understanding location management schemes regardless of network types. The goal of this paper is not to propose a new location management scheme, but to highlight various key design features involved in the existing location management schemes and enhance an insight into the common underlying principles and techniques for designing more efficient and optimized location management scheme in future wireless mobile networks.

This paper is concerned with handoff mechanisms in wireless cellular networks that employ MIMO technology. To achieve optimal performance during handoff, the mobile receiver can be linked to antennas from both the base stations of the adjacent cells. Then the handoff is termed multicell handoff. The basic idea is that in a region know as the multicell handoff region, the mobile terminal communicates simultaneously with multiple base stations. The simulation results demonstrate that the multicell handoff provides an improvement of average throughput in the high spatial correlation case.

In radio resource management for cellular networks a trade-off has to be made between the congestion level, related to cell coverage and intercell interference, and the Quality of Service (QoS) or data rates of the users. This is implemented by using a fast inner power control loop and an outer rate control algorithm, working on a slower time scale.

Several schemes have been proposed for CAC and handover in wireless cellular networks. However, during the complexity of CAC and handover in wireless environment, many simplified models and assumptions are made. Also, the CAC and handover algorithms operating in real time have to make decisions without the luxury of repeated uncorrelated measurements or the future signal strength information. It should be noted that some of CAC and handover criteria information can be inherently imprecise, or the precise information is difficult to obtain. For this reason, we propose a Fuzzy Logic (FL) based approach for CAC and handover for wireless cellular networks (called FICHS), which can operate with imprecision data and non-linear functions with arbitrary complexity. To evaluated the performance of FICHS we consider CAC with priority and enforced handover. We show that FICHS has a good behavior.

Mastes' Thesis in Applied Mathematics; Since interference is the main performance-limiting factor in most wireless networks, it is crucial to characterize the interference statistics. The two main determinants of the interference are the network geometry (spatial distribution of concurrently transmitting nodes) and the path loss law (signal attenuation). In order to explain the above, the main purpose of this thesis is of study the path-loss with respect to the serving base stations (BS) and the interference factor, defined as the ratio of the sum of the path-gains from interfering BS to the path-gain from the serving BS. In this thesis, the locations of nodes are modeled as a random Poisson process. Regarding the signal propagation model, we consider a random shadowing that characterizes in a statistical manner the effect of var- ious obstacles. We provide results on the probability distribution function of both the path-loss and the interference factors.

Mobile services have seen a major upswing driven by the bandwidth hungry applications thus leading to higher data rate requirements on the wireless networks. Spectrum being the most precious resource in the wireless industry is of keen interest. Various spectrum assignment and frequency reuse schemes have been proposed in literature. However in future networks, dynamic schemes that adapt to spatio-temporal variation in the environment are desired. We thus present a hybrid spectrum assignment scheme which adapts its allocation strategies depending on user distribution in the system. Results show that the proposed dynamic spectrum assignment strategy improves spectrum utilization thereby providing a higher data rate for the users.

This chapter presents a detailed review of existing handover schemes and focuses on an analytical model developed for a Dynamic Guard Channel Scheme (DGCS), which manages adaptively the channels reserved for handover calls depending on the current status of the handover queue. The Poisson process and Markov-Modulated-Poisson-Process (MMPP) are used to model the arrival processes of new and handover calls, respectively. The accuracy of this model is demonstrated through the extensive comparisons of the analytical results against those obtained from discrete-event simulation experiments. Moreover, the analytical model is used to assess the effects of the number of channels originally reserved for handover calls, the number of dynamic channels and the burstiness of handover calls on the performance of the DGCS scheme.

With the development and popularity of various location technologies (GPS, Wireless cellular networks and etc.), people can easily access the location information of moving objects and use a variety of location-based services. In this paper, based on the feature that the location information of moving object is consecutive, we introduce the continuity in temporal and spatial as a constraint into the Sequential Pattern Mining algorithm GSP (Generalized Sequential Patterns) [3,4], and to mine frequent trajectories, and then display them in Google maps. We evaluated our method by using a large GPS dataset in real world and verified the feasibility and effectiveness of Sequential Pattern Mining algorithm in mining the frequent trajectories of multiple moving objects.