Cellular radio networks systems engineering.

by Kwan Lawrence Yeung.Thesis (Ph.D.)--Chinese University of Hong Kong, 1995.Includes bibliographical references (leaves 115-[118]).Chapter 1 --- Introduction --- p.1Chapter 1.1 --- Cellular Concept --- p.1Chapter 1.2 --- Fixed Channel Assignment --- p.2Chapter 1.3 --- Dynamic Channel Assignment --- p.2Chapter 1.4 --- Performance Evaluation of DC A --- p.3Chapter 1.5 --- Han doff Analysis --- p.3Chapter 1.6 --- Mobile Location Tracking Strategies --- p.3Chapter 1.7 --- QOS Measure --- p.4Chapter 1.8 --- Organization of Thesis --- p.4Chapter 2 --- Optimization of Channel Assignment I --- p.6Chapter 2.1 --- Introduction --- p.6Chapter 2.2 --- Generating Compact Patterns --- p.7Chapter 2.2.1 --- Regular size cells --- p.7Chapter 2.2.2 --- Irregular size cells --- p.7Chapter 2.3 --- Nominal Channel Allocation Methods --- p.10Chapter 2.3.1 --- Compact pattern allocation --- p.10Chapter 2.3.2 --- Greedy allocation --- p.11Chapter 2.3.3 --- Hybrid allocation --- p.11Chapter 2.3.4 --- The K-Optimal variations --- p.11Chapter 2.3.5 --- Backtracking strategies --- p.12Chapter 2.4 --- Performance Comparison --- p.12Chapter 2.5 --- Conclusions --- p.16Chapter 3 --- Optimization of Channel Assignment II --- p.18Chapter 3.1 --- Introduction --- p.18Chapter 3.2 --- Basic Heuristics --- p.20Chapter 3.2.1 --- Two methods for cell ordering --- p.20Chapter 3.2.2 --- Two channel assignment strategies --- p.20Chapter 3.3 --- Channel Assignments with Cell Re-ordering --- p.21Chapter 3.3.1 --- Four channel assignment algorithms --- p.21Chapter 3.3.2 --- Complexity --- p.22Chapter 3.3.3 --- An example --- p.22Chapter 3.4 --- Channel Assignment at Hotspots --- p.23Chapter 3.4.1 --- Strategy F vs strategy R --- p.23Chapter 3.4.2 --- Strategy FR --- p.24Chapter 3.5 --- Numerical Examples --- p.25Chapter 3.5.1 --- "Performance of algorithms F/CR,F/DR,R/CR and R/DR" --- p.26Chapter 3.5.2 --- Effect of X & Y on performance of algorithms FR/CR & FR/DR --- p.26Chapter 3.5.3 --- Performance of algorithms FR/CR & FR/DR --- p.27Chapter 3.6 --- Conclusions --- p.27Chapter 4 --- Compact Pattern Based DCA --- p.29Chapter 4.1 --- Introduction --- p.29Chapter 4.2 --- Compact Pattern Channel Assignment --- p.30Chapter 4.2.1 --- Data structures --- p.30Chapter 4.2.2 --- Two functions --- p.31Chapter 4.2.3 --- Two phases --- p.32Chapter 4.3 --- Performance Evaluation --- p.33Chapter 4.4 --- Conclusions --- p.36Chapter 5 --- Cell Group Decoupling Analysis --- p.37Chapter 5.1 --- Introduction --- p.37Chapter 5.2 --- One-Dimensional Cell Layout --- p.38Chapter 5.2.1 --- Problem formulation --- p.38Chapter 5.2.2 --- Calculation of blocking probability --- p.39Chapter 5.3 --- Two-Dimensional Cell Layout --- p.41Chapter 5.3.1 --- Problem formulation --- p.41Chapter 5.3.2 --- Calculation of blocking probability --- p.42Chapter 5.4 --- Illustrative Examples --- p.42Chapter 5.4.1 --- One-dimensional case --- p.42Chapter 5.4.2 --- Two-dimensional case --- p.45Chapter 5.5 --- Conclusions --- p.45Chapter 6 --- Phantom Cell Analysis --- p.49Chapter 6.1 --- Introduction --- p.49Chapter 6.2 --- Problem Formulation --- p.49Chapter 6.3 --- Arrival Rates in Phantom Cells --- p.50Chapter 6.4 --- Blocking Probability and Channel Occupancy Distribution --- p.51Chapter 6.4.1 --- Derivation of α --- p.51Chapter 6.4.2 --- Derivation of Bside --- p.52Chapter 6.4.3 --- Derivation of Bopp --- p.53Chapter 6.4.4 --- Channel occupancy distribution --- p.54Chapter 6.5 --- Numerical Results --- p.55Chapter 6.6 --- Conclusions --- p.55Chapter 7 --- Performance Analysis of BDCL Strategy --- p.58Chapter 7.1 --- Introduction --- p.58Chapter 7.2 --- Borrowing with Directional Carrier Locking --- p.58Chapter 7.3 --- Cell Group Decoupling Analysis --- p.59Chapter 7.3.1 --- Linear cellular systems --- p.59Chapter 7.3.2 --- Planar cellular systems --- p.61Chapter 7.4 --- Phantom Cell Analysis --- p.61Chapter 7.4.1 --- Call arrival rates in phantom cells --- p.62Chapter 7.4.2 --- Analytical model --- p.62Chapter 7.5 --- Numerical Examples --- p.63Chapter 7.5.1 --- Linear cellular system with CGD analysis --- p.63Chapter 7.5.2 --- Planar cellular system with CGD analysis --- p.65Chapter 7.5.3 --- Planar cellular system with phantom cell analysis --- p.65Chapter 7.6 --- Conclusions --- p.68Chapter 8 --- Performance Analysis of Directed Retry --- p.69Chapter 8.1 --- Introduction --- p.69Chapter 8.2 --- Directed Retry Strategy --- p.69Chapter 8.3 --- Blocking Performance of Directed Retry --- p.70Chapter 8.3.1 --- Analytical model --- p.70Chapter 8.3.2 --- Numerical examples --- p.71Chapter 8.4 --- HandofF Analysis for Directed Retry --- p.73Chapter 8.4.1 --- Analytical model --- p.73Chapter 8.4.2 --- Numerical examples --- p.75Chapter 8.5 --- Conclusions --- p.77Chapter 9 --- Handoff Analysis in a Linear System --- p.79Chapter 9.1 --- Introduction --- p.79Chapter 9.2 --- Traffic Model --- p.80Chapter 9.2.1 --- Call arrival rates --- p.80Chapter 9.2.2 --- Channel holding time distribution --- p.81Chapter 9.3 --- Analytical Model --- p.81Chapter 9.3.1 --- Handoff probability --- p.81Chapter 9.3.2 --- Handoff call arrival rate --- p.81Chapter 9.3.3 --- Derivation of blocking probability --- p.81Chapter 9.3.4 --- Handoff failure probability --- p.82Chapter 9.3.5 --- Finding the optimal number of guard channels --- p.83Chapter 9.4 --- Numerical Results --- p.83Chapter 9.4.1 --- System parameters --- p.83Chapter 9.4.2 --- Justifying the analysis --- p.84Chapter 9.4.3 --- The effect of the number of guard channels --- p.84Chapter 9.5 --- Conclusions --- p.85Chapter 10 --- Mobile Location Tracking Strategy --- p.88Chapter 10.1 --- Introduction --- p.88Chapter 10.2 --- Review of Location Tracking Strategies --- p.89Chapter 10.2.1 --- Fixed location area strategy --- p.89Chapter 10.2.2 --- Fixed reporting center strategy --- p.89Chapter 10.2.3 --- Intelligent paging strategy --- p.89Chapter 10.2.4 --- Time-based location area strategy --- p.89Chapter 10.2.5 --- Movement-based location area strategy --- p.90Chapter 10.2.6 --- Distance-based location area strategy --- p.90Chapter 10.3 --- Optimization of Location Area Size --- p.90Chapter 10.3.1 --- Location updating rates ´ؤ linear systems --- p.90Chapter 10.3.2 --- Location updating rates ´ؤ planar systems --- p.91Chapter 10.3.3 --- Optimal location area size ´ؤ linear systems --- p.92Chapter 10.3.4 --- Optimal location area size ´ؤ planar systems --- p.92Chapter 10.4 --- Comparison of FLA & DBLA Strategies --- p.93Chapter 10.5 --- Adaptive Location Tracking Strategy --- p.94Chapter 10.5.1 --- Mobility tracking --- p.94Chapter 10.5.2 --- Protocols for ALT strategy --- p.94Chapter 10.6 --- Numerical Examples --- p.95Chapter 10.7 --- Conclusions --- p.97Chapter 11 --- A New Quality of Service Measure --- p.99Chapter 11.1 --- Introduction --- p.99Chapter 11.2 --- QOS Measures --- p.99Chapter 11.3 --- An Example --- p.101Chapter 11.4 --- Case Studies --- p.101Chapter 11.5 --- Conclusions --- p.106Chapter 12 --- Discussions & Conclusions --- p.107Chapter 12.1 --- Summary of Results --- p.107Chapter 12.2 --- Topics for Future Research --- p.108Chapter A --- Borrowing with Directional Channel Locking Strategy --- p.110Chapter B --- Derivation of p2 --- p.112Chapter C --- Publications Derived From This Thesis --- p.114Bibliography --- p.11

Performance analysis of the interference adaptation dynamic channel allocation technique in wireless communication networks

Dynamic channel allocation (DCA) problem is one of the major research topics in the wireless networking area. The purpose of this technique is to relieve the contradiction between the increasing traffic load in wireless networks and the limited bandwidth resource across the air interface. The challenge of this problem comes from the following facts: a) even the basic DCA problem is shown to be NP-complete (none polynomial complete); b) the size of the state space of the problem is very large; and c) any practical DCA algorithm should run in real-time. Many heuristic DCA schemes have been proposed in the literature. It has been shown through simulation results that the interference adaptive dynamic channel allocation (IA-DCA) scheme is a promising strategy in Time Devision [sic] Multiple Accesss/Frequency Devision [sic] Multiple Accesss [sic] (TDMA/FDMA) based wireless communication systems. However, the analytical work on the IA-DCA strategy in the literature is nearly blank. The performance of a, DCA algorithm in TDMA/FDMA wireless systems is influenced by three factors: representation of the interference, traffic fluctuation, and the processing power of the algorithm. The major obstacle in analyzing IA-DCA is the computation of co-channel interference without the constraint of conventional channel reuse factors. To overcome this difficulty, one needs a representation pattern which can approximate the real interference distribution as accurately as desired, and is also computationally viable. For this purpose, a concept called channel reuse zone (CRZ) is introduced and the methodology of computing the area of a CRZ with an arbitrary, non-trivial channel reuse factor is defined. Based on this new concept, the computation of both downlink and uplink CO-channel interference is investigated with two different propagation models, namely a simplified deterministic model and a shadowing model. For the factor of the processing power, we proposed an idealized Interference Adaptation Maximum Packing (IAMP) scheme, which gives the upper bound of all IA-DCA schemes in terms of the system capacity. The effect of traffic dynamics is delt [sic] with in two steps. First, an asymptotic performance bound for the IA-DCA strategy is derived with the assumption of an arbitrarily large number of channels in the system. Then the performance bound for real wireless systems with the IA-DCA strategy is derived by alleviating this assumption. Our analytical result is compared with the performance bound drawn by Zander and Eriksson for reuse-partitioning DCA1 and some simulation results for IA-DCA in the literature. It turns out that the performance bound obtained in this work is much tighter than Zander and Eriksson\u27s bound and is in agreement with simulation results. 1only available for deterministic propagation model and downlink connection

Handover and Channel Allocation Mechanisms in Mobile Satellite Networks

In this work we study first handover prediction in non-geostationary mobile satellite networks. The ultimate choice of the transition path depends on UT position and signal strength. We investigate the procedure of beam monitoring and propose UT maximum residence as the criterion for path selection. The UT must operate both in full- and half-duplex mode, the latter being desirable when power limitations are imposed. We propose a scheme that achieves this goal and guarantees efficient diversity provision. Constant delay contours on the earth's surface are defined. The problem of reliable time delay acquisition is addressed, in case synchronization is lost. The SBS solves that either by using the known estimate of UT position or by requesting a measurement report by the UT. The problem of channel allocation appears in cellular networks of every kind. Calls arising in the cell overlap area have access to channels of more than one base station and may choose which base station they will use to establish connection. In that case the problems of base station and channel assignment arise jointly. We address the problem in a linear cellular network and aim at the minimumnumber of utilized channels. We present two algorithms: The first one expands Load Balancing in clique populations and is Sequential Clique Load Balancing (SCLB). The second one is named Clique Load Balancing with Inverse Water-Filling (CLB-IWF). In a dynamic environment, we unify SCLB and CLB-IWF into CLB-DA, which comprises Dynamic Allocation. CLB-DA is compared with Least Loaded Routing (LLR) policy and with Random Routing policy. We finally deduce that at light loads CLB-DA outperforms LLR, attaining smaller blocking probability, whereas at heavier loads all three policies converge

Eficiência energética avançada para sistema OFDMA CoMP coordenação multiponto

Doutoramento em Engenharia EletrotécnicaThe ever-growing energy consumption in mobile networks stimulated by the expected growth in data tra ffic has provided the impetus for mobile operators to refocus network design, planning and deployment towards reducing the cost per bit, whilst at the same time providing a signifi cant step towards reducing their operational expenditure. As a step towards incorporating cost-eff ective mobile system, 3GPP LTE-Advanced has adopted the coordinated multi-point (CoMP) transmission technique due to its ability to mitigate and manage inter-cell interference (ICI). Using CoMP the cell average and cell edge throughput are boosted. However, there is room for reducing energy consumption further by exploiting the inherent exibility of dynamic resource allocation protocols. To this end packet scheduler plays the central role in determining the overall performance of the 3GPP longterm evolution (LTE) based on packet-switching operation and provide a potential research playground for optimizing energy consumption in future networks. In this thesis we investigate the baseline performance for down link CoMP using traditional scheduling approaches, and subsequently go beyond and propose novel energy e fficient scheduling (EES) strategies that can achieve power-e fficient transmission to the UEs whilst enabling both system energy effi ciency gain and fairness improvement. However, ICI can still be prominent when multiple nodes use common resources with di fferent power levels inside the cell, as in the so called heterogeneous networks (Het- Net) environment. HetNets are comprised of two or more tiers of cells. The rst, or higher tier, is a traditional deployment of cell sites, often referred to in this context as macrocells. The lower tiers are termed small cells, and can appear as microcell, picocells or femtocells. The HetNet has attracted signiffi cant interest by key manufacturers as one of the enablers for high speed data at low cost. Research until now has revealed several key hurdles that must be overcome before HetNets can achieve their full potential: bottlenecks in the backhaul must be alleviated, as well as their seamless interworking with CoMP. In this thesis we explore exactly the latter hurdle, and present innovative ideas on advancing CoMP to work in synergy with HetNet deployment, complemented by a novel resource allocation policy for HetNet tighter interference management. As system level simulator has been used to analyze the proposed algorithm/protocols, and results have concluded that up to 20% energy gain can be observed.O aumento do consumo de energia nas TICs e em particular nas redes de comunicação móveis, estimulado por um crescimento esperado do tráfego de dados, tem servido de impulso aos operadores m oveis para reorientarem os seus projectos de rede, planeamento e implementa ção no sentido de reduzir o custo por bit, o que ao mesmo tempo possibilita um passo signicativo no sentido de reduzir as despesas operacionais. Como um passo no sentido de uma incorporação eficaz em termos destes custos, o sistema móvel 3GPP LTE-Advanced adoptou a técnica de transmissão Coordenação Multi-Ponto (identificada na literatura com a sigla CoMP) devido à sua capacidade de mitigar e gerir Interferência entre Células (sigla ICI na literatura). No entanto a ICI pode ainda ser mais proeminente quando v arios n os no interior da célula utilizam recursos comuns com diferentes níveis de energia, como acontece nos chamados ambientes de redes heterogéneas (sigla Het- Net na literatura). As HetNets são constituídas por duas ou mais camadas de células. A primeira, ou camada superiora, constitui uma implantação tradicional de sítios de célula, muitas vezes referidas neste contexto como macrocells. Os níveis mais baixos são designados por células pequenas, e podem aparecer como microcells, picocells ou femtocells. A HetNet tem atra do grande interesse por parte dos principais fabricantes como sendo facilitador para transmissões de dados de alta velocidade a baixo custo. A investigação tem revelado at e a data, vários dos principais obstáculos que devem ser superados para que as HetNets possam atingir todo o seu potencial: (i) os estrangulamentos no backhaul devem ser aliviados; (ii) bem como sua perfeita interoperabilidade com CoMP. Nesta tese exploramos este ultimo constrangimento e apresentamos ideias inovadoras em como a t ecnica CoMP poder a ser aperfeiçoada por forma a trabalhar em sinergia com a implementação da HetNet, complementado ainda com uma nova perspectiva na alocação de recursos rádio para um controlo e gestão mais apertado de interferência nas HetNets. Com recurso a simulação a níível de sistema para analisar o desempenho dos algoritmos e protocolos propostos, os resultados obtidos concluíram que ganhos at e a ordem dos 20% poderão ser atingidos em termos de eficiência energética

Frequency Selective Surface Assisted Dynamic Spectrum Access for the Wireless Indoor Environment

This thesis investigates the impact of the use of Frequency Selective Surfaces (FSS) when applied to walls to improve the performance of indoor wireless communications. FSS controlled spectrum sharing is examined using a point-to-point network topology containing two different types of users, intra-room and inter-room, and considers a system with open spectrum access where all users have equal regulatory status. This approach is used together with FSS walls to smartly control resource assignment inside the building. The FSS filter activation threshold is examined, using a threshold value measured from sensing interference in up to three spectrum bands. It is shown how using this threshold, and different FSS state activation strategies, can significantly improve the way an indoor wireless communications system can control its spectrum resources. Different FSS activation strategies are explored. It is shown how the model where a specific value of FSS threshold is set and used throughout shows much better performance compared to situations where the FSS is either continually on or continually off. This performance can be further improved if a more deterministic value is used. This is achieved by using a sliding window average assessment of performance which aims to minimize the frequency of instantaneous FSS states changes; this means a statistical value is used to determine when to activate the FSS. The result shows that a longer sliding window tends to give a better performance for inter-room users without significantly decreasing the performance of intra-room users. An analytical model of system performance using a two-dimensional Markov Chain is developed. Systems with One Available Spectrum (1AS) and Two Available Spectrums (2AS) have been analysed using a state-transition-rate diagram and global equilibrium expressions for both systems are presented

Interference mitigation and interference avoidance for cellular OFDMA-TDD networks

In recent years, cellular systems based on orthogonal frequency division multiple access – time division duplex (OFDMA-TDD) have gained considerable popularity. Two of the major reasons for this are, on the one hand, that OFDMA enables the receiver to effectively cope with multipath propagation while keeping the complexity low. On the other hand, TDD offers efficient support for cell-specific uplink (UL)/downlink (DL) asymmetry demands by allowing each cell to independently set its UL/DL switching point (SP). However, cell-independent SP gives rise to crossed slots. In particular, crossed slots arise when neighbouring cells use the same slot in opposing link directions, resulting in base station (BS)-to-BS interference and mobile station (MS)-to-MS interference. BS-to-BS interference, in particular, can be quite detrimental due to the exposed location of BSs, which leads to high probability of line-of-sight (LOS) conditions. The aim of this thesis is to address the BS-to-BS interference problem in OFDMA-TDDcellular networks. A simulation-based approach is used to demonstrate the severity of BS-to-BS interference and a signal-to-interference-plus-noise ratio (SINR) equation for OFDMA is formulated to aid system performance analysis. The detrimental effects of crossed slot interference in OFDMA-TDD cellular networks are highlighted by comparing methods specifically targeting the crossed slots interference problem. In particular, the interference avoidance method fixed slot allocation (FSA) is compared against state of the art interference mitigation approaches, viz: random time slot opposing (RTSO) and zone division (ZD). The comparison is done based on Monte Carlo simulations and the main comparison metric is spectral efficiency calculated using the SINR equation formulated in this thesis. The simulation results demonstrate that when LOS conditions among BSs are present, both RTSO and ZD perform worse than FSA for all considered performance metrics. It is concluded from the results that current interference mitigation techniques do not offer an effective solution to the BS-to-BS interference problem. Hence, new interference avoidance methods, which unlike FSA, do not sacrifice the advantages of TDD are open research issues addressed in this thesis. The major contribution of this thesis is a novel cooperative resource balancing technique that offers a solution to the crossed slot problem. The novel concept, termed asymmetry balancing, is targeted towards next-generation cellular systems, envisaged to have ad hoc and multi-hop capabilities. Asymmetry balancing completely avoids crossed slots by keeping the TDD SPs synchronised among BSs. At the same time, the advantages of TDD are retained, which is enabled by introducing cooperation among the entities in the network. If a cell faces resource shortage in one link direction, while having free resources in the opposite link direction, the free resources can be used to support the overloaded link direction. In particular, traffic can be offloaded to near-by mobile stations at neighbouring cells that have available resources. To model the gains attained with asymmetry balancing, a mathematical framework is developed which is verified by Monte Carlo simulations. In addition, asymmetry balancing is compared against both ZD and FSA based on simulations and the results demonstrate the superior performance of asymmetry balancing. It can be concluded that the novel interference avoidance approach is a very promising candidate t