Cellular system information capacity change at higher frequencies due to propagation loss and system parameters

In this paper, mathematical analysis supported by computer simulation is used to study cellular system information capacity change due to propagation loss and system parameters (such as path loss exponent, shadowing and antenna height) at microwave carrier frequencies greater than 2 GHz and smaller cell size radius. An improved co-channel interference model, which includes the second tier co-channel interfering cells is used for the analysis. The system performance is measured in terms of the uplink information capacity of a time-division multiple access (TDMA) based cellular wireless system. The analysis and simulation results show that the second tier co-channel interfering cells become active at higher microwave carrier frequencies and smaller cell size radius. The results show that for both distance-dependent: path loss, shadowing and effective road height the uplink information capacity of the cellular wireless system decreases as carrier frequency increases and cell size radius R decreases. For example at a carrier frequency fc = 15.75 GHz, basic path loss exponent α = 2 and cell size radius R = 100, 500 and 1000m the decrease in information capacity was 20, 5.29 and 2.68%

Sensitivity of cellular wireless network performance to system & propagation parameters at carrier frequencies greater than 2 GHz

In this paper, mathematical analysis supported by computer simulation is used to investigate the impact of both system and propagation loss parameters on the performance of cellular wireless network operating at microwave carrier frequencies greater than 2 GHz, where multiple tier of co-channel interfering cells are considered to be active. The two-slope path loss model and the uplink information capacity of the cellular network is used for the performance analysis. Results show that for carrier frequencies greater than 2 GHz and smaller cell radius multiple tier of co-channel interfering cells become active as compared to carrier frequencies lesser than 2 GHz. The multiple tier of co-channel interfering cells, leads to a decrease in the information capacity of the cellular wireless network. The results also show that the system performance is sensitive to most of the propagation model parameters such as the basic and extra path loss exponent

MODELS FOR GREENFIELD AND INCREMENTAL CELLULAR NETWORK PLANNING

Mobility, as provided in cellular networks, is largely affected by the location of the base stations. To a large extent, the location of base stations is determined by the quantity of base stations available to provide coverage. It is therefore not surprising that the quantity and subsequent location of base stations will not only impact service delivery but also have a large associated cost for implementation. Generally, the higher the quantity of base stations required to provide coverage, the greater the cost of implementation and operation of the radio network. This thesis proposes a modified optimization model to aid the cell planning process. This model, unlike those surveyed, is applicable to both green field and incremental network designs. The variation in model design is fundamental in ensuring cost effective growth and expansion of cellular networks. Numerical studies of the modified model applied to both abstract and real system configurations are carried out using MATLAB. Terrain data from Kampala, Uganda, was used to aid the study. Results show that the antenna height significantly determines the solution of the objective function. In addition, it is shown that slight variations in the cost association between the antenna height and the site construction requirements can be decisively used for predefined targeted network planning. A comparison is also made between an actual network installation and the estimates provided by the model. As expected, results from the study show that the difference between the estimated count and the actual count can be adEquately minimized by slight variations in antenna height requirements

Modelling and Analysis of Resource Management Schemes in Wireless Networks. Analytical Models and Performance Evaluation of Handoff Schemes and Resource Re-Allocation in Homogeneous and Heterogeneous Wireless Cellular Networks.

Over recent years, wireless communication systems have been experiencing a dramatic and continuous growth in the number of subscribers, thus placing extra demands on system capacity. At the same time, keeping Quality of Service (QoS) at an acceptable level is a critical concern and a challenge to the wireless network designer. In this sense, performance analysis must be the first step in designing or improving a network. Thus, powerful mathematical tools for analysing most of the performance metrics in the network are required. A good modelling and analysis of the wireless cellular networks will lead to a high level of QoS. In this thesis, different analytical models of various handoff schemes and resource re-allocation in homogeneous and heterogeneous wireless cellular networks are developed and investigated. The sustained increase in users and the request for advanced services are some of the key motivations for considering the designing of Hierarchical Cellular Networks (HCN). In this type of system, calls can be blocked in a microcell flow over to an overlay macrocell. Microcells in the HCN can be replaced by WLANs as this can provide high bandwidth and its users have limited mobility features. Efficient sharing of resources between wireless cellular networks and WLANs will improve the capacity as well as QoS metrics. This thesis first presents an analytical model for priority handoff mechanisms, where new calls and handoff calls are captured by two different traffic arrival processes, respectively. Using this analytical model, the optimised number of channels assigned to II handover calls, with the aim of minimising the drop probability under given network scenarios, has been investigated. Also, an analytical model of a network containing two cells has been developed to measure the different performance parameters for each of the cells in the network, as well as altogether as one network system. Secondly, a new solution is proposed to manage the bandwidth and re-allocate it in a proper way to maintain the QoS for all types of calls. Thirdly, performance models for microcells and macrocells in hierarchical cellular networks have been developed by using a combination of different handoff schemes. Finally, the microcell in HCN is replaced by WLANs and a prioritised vertical handoff scheme in an integrated UMTS/WLAN network has been developed. Simulation experiments have been conducted to validate the accuracy of these analytical models. The models have then been used to investigate the performance of the networks under different scenarios

Quantifying Potential Energy Efficiency Gain in Green Cellular Wireless Networks

Conventional cellular wireless networks were designed with the purpose of providing high throughput for the user and high capacity for the service provider, without any provisions of energy efficiency. As a result, these networks have an enormous Carbon footprint. In this paper, we describe the sources of the inefficiencies in such networks. First we present results of the studies on how much Carbon footprint such networks generate. We also discuss how much more mobile traffic is expected to increase so that this Carbon footprint will even increase tremendously more. We then discuss specific sources of inefficiency and potential sources of improvement at the physical layer as well as at higher layers of the communication protocol hierarchy. In particular, considering that most of the energy inefficiency in cellular wireless networks is at the base stations, we discuss multi-tier networks and point to the potential of exploiting mobility patterns in order to use base station energy judiciously. We then investigate potential methods to reduce this inefficiency and quantify their individual contributions. By a consideration of the combination of all potential gains, we conclude that an improvement in energy consumption in cellular wireless networks by two orders of magnitude, or even more, is possible.Comment: arXiv admin note: text overlap with arXiv:1210.843

Radio network planning and optimisation for WCDMA

The present thesis introduces the radio network planning process and optimisation for WCDMA (FDD mode), as defined by 3GPP. This thesis consists of three parts: modelling and tools for radio network planning, process for pre-operational network control and optimisation for the operational network. General challenges to face in 3G network control are based on the fact that many issues are interconnected and should be simultaneously considered, such as Planning means not only to meet current status and demands, but the solution should also comply with the future requirements by providing an acceptable development path. Traffic modelling is not only the question about the total amount of traffic growth, but also the question about the future service distribution and performance demands. All CDMA systems have a relation between capacity and coverage. Consequently, the network planning itself is not only based on propagation estimation but also on the interference situation in the network. Ideally, site selection consideration will be done based on the network analysis with planned load and traffic/service portfolio, taking possible co-siting constraints into account. Provision of multiple services and seamless management of at least two multiple access systems require rapid evolution of the management tools and processes. The network performance in terms of capacity, quality, and implementation and operational costs forms a multidimensional space. Operators' task will be to convert the business strategy to an operating point in the performance space in a cost efficient manner. The contribution of this thesis in terms of modelling and tools is as follows: Improvement of the accuracy of radio link budget by introducing power control headroom (also called fast fading margin). Improvement of loading equation by introducing a transmit power increase term. Development of theory and modelling for a planning tool capable of multi-service and multi-carrier interference, capacity and coverage analysis. Development and implementation an interface taking into account the true traffic distribution (not uniform) and terminal speed. In the area of pre-operational planning process the contribution of this thesis is as follows: Development of dimensioning methodology for multi-service network site density estimation, utilising the modelling of power control headroom, transmit power increase, soft handover and Eb/N0. Development of radio network planning process for multi-service environment including capacity and coverage evaluation for a given traffic mixture, quality and area requirements. Analysis of means to improve radio network performance with Mast Head Amplifier (MHA), diversity reception, sectorisation and proper antenna selection. In the area of optimisation of the operational network the contribution of this thesis is as follows: Definition for optimisation target in the case of 3G. The optimisation will be capacity-quality trade-off management instead of plain quality improvement process. Introduction of Self Organizing Map (SOM) in the analysis of cellular networks. Analysis of the applicability of SOM in WCDMA cellular network optimisation. Introduction of SOM based applications to support network capacity-quality trade-off management. It is worth noting that process and methods described in this work are not limited to 3G systems with WCDMA radio access technology, but they are applicable to other CDMA standards as well.reviewe

On the Fundamentals of Stochastic Spatial Modeling and Analysis of Wireless Networks and its Impact to Channel Losses

With the rapid evolution of wireless networking, it becomes vital to ensure transmission reliability, enhanced connectivity, and efficient resource utilization. One possible pathway for gaining insight into these critical requirements would be to explore the spatial geometry of the network. However, tractably characterizing the actual position of nodes for large wireless networks (LWNs) is technically unfeasible. Thus, stochastical spatial modeling is commonly considered for emulating the random pattern of mobile users. As a result, the concept of random geometry is gaining attention in the field of cellular systems in order to analytically extract hidden features and properties useful for assessing the performance of networks. Meanwhile, the large-scale fading between interacting nodes is the most fundamental element in radio communications, responsible for weakening the propagation, and thus worsening the service quality. Given the importance of channel losses in general, and the inevitability of random networks in real-life situations, it was then natural to merge these two paradigms together in order to obtain an improved stochastical model for the large-scale fading. Therefore, in exact closed-form notation, we generically derived the large-scale fading distributions between a reference base-station and an arbitrary node for uni-cellular (UCN), multi-cellular (MCN), and Gaussian random network models. In fact, we for the first time provided explicit formulations that considered at once: the lattice profile, the users’ random geometry, the spatial intensity, the effect of the far-field phenomenon, the path-loss behavior, and the stochastic impact of channel scatters. Overall, the results can be useful for analyzing and designing LWNs through the evaluation of performance indicators. Moreover, we conceptualized a straightforward and flexible approach for random spatial inhomogeneity by proposing the area-specific deployment (ASD) principle, which takes into account the clustering tendency of users. In fact, the ASD method has the advantage of achieving a more realistic deployment based on limited planning inputs, while still preserving the stochastic character of users’ position. We then applied this inhomogeneous technique to different circumstances, and thus developed three spatial-level network simulator algorithms for: controlled/uncontrolled UCN, and MCN deployments

Resource Allocation for Cellular/WLAN Integrated Networks

The next-generation wireless communications have been envisioned to be supported by heterogeneous networks using various wireless access technologies. The popular cellular networks and wireless local area networks (WLANs) present perfectly complementary characteristics in terms of service capacity, mobility support, and quality-of-service (QoS) provisioning. The cellular/WLAN interworking is thus an effective way to promote the evolution of wireless networks. As an essential aspect of the interworking, resource allocation is vital for efficient utilization of the overall resources. Specially, multi-service provisioning can be enhanced with cellular/WLAN interworking by taking advantage of the complementary network strength and an overlay structure. Call assignment/reassignment strategies and admission control policies are effective resource allocation mechanisms for the cellular/WLAN integrated network. Initially, the incoming calls are distributed to the overlay cell or WLAN according to call assignment strategies, which are enhanced with admission control policies in the target network. Further, call reassignment can be enabled to dynamically transfer the traffic load between the overlay cell and WLAN via vertical handoff. By these means, the multi-service traffic load can be properly shared between the interworked systems. In this thesis, we investigate the load sharing problem for this heterogeneous wireless overlay network. Three load sharing schemes with different call assignment/reassignment strategies and admission control policies are proposed and analyzed. Effective analytical models are developed to evaluate the QoS performance and determine the call admission and assignment parameters. First, an admission control scheme with service-differentiated call assignment is studied to gain insights on the effects of load sharing on interworking effectiveness. Then, the admission scheme is extended by using randomized call assignment to enable distributed implementation. Also, we analyze the impact of user mobility and data traffic variability. Further, an enhanced call assignment strategy is developed to exploit the heavy-tailedness of data call size. Last, the study is extended to a multi-service scenario. The overall resource utilization and QoS satisfaction are improved substantially by taking into account the multi-service traffic characteristics, such as the delay-sensitivity of voice traffic, elasticity and heavy-tailedness of data traffic, and rate-adaptiveness of video streaming traffic

Feasibility of wireless mesh for LTE-Advanced small cell access backhaul

Mobiilidatan määrä on muutaman viime vuoden aikana kasvanut voimakkaasti ja nykyiset ennustukset arvioivat eksponentiaalista kasvukäyrää tulevien vuosien aikana. Matkapuhelinjärjestelmät ovat kehittyneet nopeasti tämän trendin ohjaamana. Neljännen sukupolven matkapuhelinverkkostandardien myötä, uudet innovaatiot kuten heterogeeniset verkkoratkaisut tarjoavat ratkaisun nykyisiin skaalautuvuus- ja kapasiteettiongelmiin. Joitain ilmeisiä ongelmakohtiakin kuitenkin esiintyy kuten heterogeenisten verkkojen runkokytkennän toteuttaminen. Yksi lupaavimmista tavoista toteuttaa heterogeenisten verkkojen runkokytkentä on langaton ja itseorganisoituva mesh-verkko. Tämän opinnäytetyön tavoitteena on varmistaa ja testata Nokia Siemens Networksin kehittämän mesh-runkokytkentäverkkokonseptin toteutettavuutta ja toiminnallisuutta soveltuvan validointijärjestelmän avulla. Kaiken kaikkiaan validointijärjestelmä ja sen päälle toteutettu mesh-protokolla toimivat moitteettomasti koko kehitys- ja testausprosessin ajan. Konseptin eri ominaisuudet ja mekanismit todistettiin täysin toteutettaviksi ja toimiviksi. Muutamalla lisäominaisuudella ja konseptiparannuksella mesh-konsepti tarjoaa houkuttelevan ja innovatiivisen ratkaisun heterogeenisten verkkojen runkokytkentään tulevaisuudessa.Mobile traffic demands and volumes are increasing and will dramatically keep increasing in the future. Along with this, mobile networks have evolved to better match this growth. Fourth generation cellular network standard introduced a set of new innovations for mobile communications, including support for heterogeneous network deployments. Heterogeneous networking is the likely answer for future mobile data capacity shortage but also poses some challenges, the most evident being how to implement the backhauling. One of the most promising heterogeneous network backhaul solutions is a meshed radio system with self-organizing features. The main scope of this master's thesis is the verification of functionality and feasibility of a wireless mesh backhaul concept developed by Nokia Siemens Networks through a proof-of-concept system. All in all, the wireless mesh proof-of-concept system performed strongly throughout the development and testing process. The different functionalities were proven to work successfully together. With further development and enhancement, the system concept displays extreme potential for a state-of-the-art heterogeneous network backhaul technology

ENABLING SMART CITY SERVICES FOR HETEROGENEOUS WIRELESS NETWORKS

A city can be transformed into a smart city if there is a resource-rich and reliable communication infrastructure available. A smart city in effect improves the quality of life of citizens by providing the means to convert the existing solutions to smart ones. Thus, there is a need for finding a suitable network structure that is capable of providing sufficient capacity and satisfactory quality-of-service in terms of latency and reliability. In this thesis, we propose a wireless network structure for smart cities. Our proposed network provides two wireless interfaces for each smart city node. One is supposed to connect to a public WiFi network, while the other is connected to a cellular network (such as LTE). Indeed, Multi-homing helps different applications to use the two interfaces simultaneously as well as providing the necessary redundancy in case the connection of one interface is lost. The performance of our proposed network structure is investigated using comprehensive ns-2 computer simulations. In this study, high data rate real-time and low data rate non-real-time applications are considered. The effect of a wide range of network parameters is tested such as the WiFi transmission rate, LTE transmission rate, the number of real-time and non-real-time nodes, application traffic rate, and different wireless propagation models. We focus on critical quality-of-service (QoS) parameters such as packet delivery delay and packet loss. We also measured the energy consumed in packet transmission. Compared with a single-interface WiFi-based or an LTE-based network, our simulation results show the superiority of the proposed network structure in satisfying QoS with lower latency and lower packet loss. We found also that the proposed multihoming structure enables the smart city sensors and other applications to realize a greener communication by consuming a lesser amount of transmission power rather than single interface-based networks