Spectrum Sharing Optimization and Analysis in Cellular Networks under Target Performance and Budget Restriction

Dynamic Spectrum Sharing (DSS) aims to provide opportunistic access to under-utilised spectrum in cellular networks for secondary network operators. In this paper we propose an algorithm using stochastic and optimisation models to borrow spectrum bandwidths under the assumption that more resources exist for secondary access than the secondary network demand by considering a merchant mode. The main aim of the paper is to address the problem of spectrum borrowing in DSS environments, where a secondary network operator aims to borrow the required spectrum from multiple primary network operators to achieve a maximum profit under specific grade of service (GoS) and budget restriction. We assume that the primary network operators offer spectrum access opportunities with variable number of channels (contiguous and/or non-contiguous) at variable prices. Results obtained are then compared with results derived from an algorithm in which spectrum borrowing are random. Comparisons showed that the gain in the results obtained from our proposed stochastic-optimisation framework is significantly higher than random counterpart

Dynamic Spectrum Sharing Optimization and Post-optimization Analysis with Multiple Operators in Cellular Networks

Dynamic spectrum sharing aims to provide secondary access to under-utilised spectrum in cellular networks. The main aim of the paper is twofold. Firstly, secondary operator aims to borrow spectrum bandwidths under the assumption that more spectrum resources exist considering a merchant mode. Two optimization models are proposed using stochastic and optimization models in which the secondary operator (i) spends the minimal cost to achieve the target grade of service assuming unrestricted budget or (ii) gains the maximal profit to achieve the target grade of service assuming restricted budget. Results obtained from each model are then compared with results derived from algorithms in which spectrum borrowings are random. Comparisons showed that the gain in the results obtained from our proposed stochastic-optimization framework is significantly higher than heuristic counterparts. Secondly, post-optimization performance analysis of the operators in the form of blocking probability in various scenarios is investigated to determine the probable performance gain and degradation of the secondary and primary operators respectively. We mathematically model the sharing agreement scenario and derive the closed form solution of blocking probabilities for each operator. Results show how the secondary operator perform in terms of blocking probability under various offered loads and sharing capacit

Efficient resource allocation and call admission control in high capacity wireless networks

Resource Allocation (RA) and Call Admission Control (CAC) in wireless networks are processes that control the allocation of the limited radio resources to mobile stations (MS) in order to maximize the utilization efficiency of radio resources and guarantee the Quality of Service (QoS) requirements of mobile users. In this dissertation, several distributed, adaptive and efficient RA/CAC schemes are proposed and analyzed, in order to improve the system utilization while maintaining the required QoS. Since the most salient feature of the mobile wireless network is that users are moving, a Mobility Based Channel Reservation (MBCR) scheme is proposed which takes the user mobility into consideration. The MBCR scheme is further developed into PMBBR scheme by using the user location information in the reservation making process. Through traffic composition analysis, the commonly used assumption is challenged in this dissertation, and a New Call Bounding (NCB) scheme, which uses the number of channels that are currently occupied by new calls as a decision variable for the CAC, is proposed. This dissertation also investigates the pricing as another dimension for RA/CAC. It is proven that for a given wireless network there exists a new call arrival rate which can maximize the total utility of users, while maintaining the required QoS. Based on this conclusion, an integrated pricing and CAC scheme is proposed to alleviate the system congestion

Generalised Radio Resource Sharing Framework for Heterogeneous Radio Networks

Recent years have seen a significant interest in quantitative measurements of licensed and unlicensed spectrum use. Several research groups, companies and regulatory bodies have conducted studies of varying times and locations with the aim to capture the over- all utilisation rate of spectrum. The studies have shown that large amount of allocated spectrum are under-utilised, and create the so called \spectrum holes", resulting in a waste of valuable frequency resources. In order to satisfy the requirements of increased demands of spectrum resources and to improve spectrum utilisation, dynamic spectrum sharing (DSS) is proposed in the literature along with cognitive radio networks (CRNs). DSS and CRNs have been studied from many perspectives, for example spectrum sensing to identify the idle channels has been under the microscope to improve detection proba- bility. As well as spectrum sensing, the DSS performance analysis remains an important topic moving towards better spectrum utilisation to meet the exponential growth of traffi�c demand. In this dissertation we have studied both techniques to achieve different objectives such as enhancing the probability of detection and spectrum utilisation. In order to improve spectrum sensing decisions we have proposed a cooperative spec- trum sensing scheme which takes the propagation conditions into consideration. The proposed location aware scheme shows an improved performance over conventional hard combination scheme, highlighting the requirements of location awareness in cognitive radio networks (CRNs). Due to the exponentially growing wireless applications and services, traffi�c demand is increasing rapidly. To cope with such growth wireless network operators seek radio resource cooperation strategies for their users with the highest possible grade of service (GoS). However, it is diffi�cult to fathom the potential benefits of such cooperation, thus we propose a set of analytical models for DSS to analyse the blocking probability gain and degradation for operators. The thesis focuses on examining the performance gains that DSS can entail, in different scenarios. A number of dynamic spectrum sharing scenarios are proposed. The proposed models focus on measuring the blocking probability of secondary network operators as a trade-o� with a marginal increase of the blocking probability of a primary network in return of monetary rewards. We derived the global balance equation and an explicit expression of the blocking probability for each model. The robustness of the proposed analytical models is evaluated under different scenarios by considering varying tra�c intensities, different network sizes and adding reserved resources (or pooled capacity). The results show that the blocking probabilities can be reduced significantly with the proposed analytical DSS models in comparison to the existing local spectrum access schemes. In addition to the sharing models, we further assume that the secondary operator aims to borrow spectrum bandwidths from primary operators when more spectrum resources available for borrowing than the actual demand considering a merchant mode. Two optimisation models are proposed using stochastic optimisation models in which the secondary operator (i) spends the minimum amount of money to achieve the target GoS assuming an unrestricted budget or (ii) gains the maximum amount of pro�t to achieve the target GoS assuming restricted budget. Results obtained from each model are then compared with results derived from algorithms in which spectrum borrowings were random. Comparisons showed that the gain in the results obtained from our pro- posed stochastic optimisation model is significantly higher than heuristic counterparts. A post-optimisation performance analysis of the operators in the form of analysis of blocking probability in various scenarios is investigated to determine the probable per- formance gain and degradation of the secondary and primary operators respectively. We mathematically model the sharing agreement scenario and derive the closed form solution of blocking probabilities for each operator. Results show how the secondary and primary operators perform in terms of blocking probability under various offered loads and sharing capacity. The simulation results demonstrate that at most trading windows, the proposed opti- mal algorithms outperforms their heuristic counterparts. When we consider 80 cells, the proposed pro�t maximisation algorithm results in 33.3% gain in net pro�t to the secondary operators as well as facilitating 2.35% more resources than the heuristic ap- proach. In addition, the cost minimisation algorithm results in 46.34% gain over the heuristic algorithm when considering the same number of cells (80)

A new charging scheme for ATM based on QoS

PhDNew services are emerging rapidly within the world of telecommunications. Charging strategies that were appropriate for individual transfer capabilities are no longer appropriate for an integrated broadband communications network. There is currently a range of technologies (such as cable television, telephony and narrow band ISDN) for the different services in use and a limited number of charging schemes are applicable for each of the underlying technologies irrespective of the services used over it. Difficulties arise when a wide range of services has to be supported on the same integrated technology such as asynchronous transfer mode (ATM); in such cases the type of service in use and the impact it has on the network becomes much more important. The subject of this thesis, therefore, is the charging strategies for integrated broadband communications networks. That is, the identification of the requirements associated with ATM charging schemes and the proposal of a new approach to charging for ATM called the “quality of service based charging scheme”. Charging for ATM is influenced by three important components: the type and content of a service being offered; the type of customer using the services; and the traffic characteristics belonging to the application supporting the services. The first two issues will largely be dependent on the business and regulatory requirements of the operators. The last item, and an essential one for ATM, is the bridge between technology and business; how are the resources used by a service quantified? Charging that is based on resource usage at the network level was the prime focus of the research reported here. With the proposed charging scheme, a distinction is first made between the four different ATM transfer capabilities that will support various services and the different quality of service requirements that may be applicable to each of them. Then, resources are distributed among buffers set-up to support the combination of these transfer capabilities and quality of services. The buffers are dimensioned according to the M/D/1/K and the ND/D/1 queuing analysis to determine the buffer efficiency and quality of service requirements. This dimensioning provides the basis for fixing the price per unit of resource and time. The actual resource used by a connection is based on the volume of cells transmitted or peak cell rate allocation in combination with traffic shapers if appropriate. Shapers are also dimensioned using the quality of service parameters. Since the buffer 4 efficiency is dependent on the quality of service requirements, users (customers) of ATM networks buy quality of service. The actual price of a connection is further subjected to a number of transformations based on the size of the resource purchased, the time of the day at which a connection is made, and the geographical locality of the destination switch. It is demonstrated that the proposed charging scheme meets all the requirements of customers and of network operators. In addition the result of the comparison of the new scheme with a number of existing, prominent, ATM charging schemes is presented, showing that the performance of the proposed scheme is better in terms of meeting the expectations of both the customers and the network operators

Satellite Networks: Architectures, Applications, and Technologies

Since global satellite networks are moving to the forefront in enhancing the national and global information infrastructures due to communication satellites' unique networking characteristics, a workshop was organized to assess the progress made to date and chart the future. This workshop provided the forum to assess the current state-of-the-art, identify key issues, and highlight the emerging trends in the next-generation architectures, data protocol development, communication interoperability, and applications. Presentations on overview, state-of-the-art in research, development, deployment and applications and future trends on satellite networks are assembled

Smart PIN: performance and cost-oriented context-aware personal information network

The next generation of networks will involve interconnection of heterogeneous individual networks such as WPAN, WLAN, WMAN and Cellular network, adopting the IP as common infrastructural protocol and providing virtually always-connected network. Furthermore, there are many devices which enable easy acquisition and storage of information as pictures, movies, emails, etc. Therefore, the information overload and divergent content’s characteristics make it difficult for users to handle their data in manual way. Consequently, there is a need for personalised automatic services which would enable data exchange across heterogeneous network and devices. To support these personalised services, user centric approaches for data delivery across the heterogeneous network are also required. In this context, this thesis proposes Smart PIN - a novel performance and cost-oriented context-aware Personal Information Network. Smart PIN's architecture is detailed including its network, service and management components. Within the service component, two novel schemes for efficient delivery of context and content data are proposed: Multimedia Data Replication Scheme (MDRS) and Quality-oriented Algorithm for Multiple-source Multimedia Delivery (QAMMD). MDRS supports efficient data accessibility among distributed devices using data replication which is based on a utility function and a minimum data set. QAMMD employs a buffer underflow avoidance scheme for streaming, which achieves high multimedia quality without content adaptation to network conditions. Simulation models for MDRS and QAMMD were built which are based on various heterogeneous network scenarios. Additionally a multiple-source streaming based on QAMMS was implemented as a prototype and tested in an emulated network environment. Comparative tests show that MDRS and QAMMD perform significantly better than other approaches

Pricing in Multi-Service Communication Networks: A Game-theoretic Approach

The promise of multi-class communication networks is gradually becoming a reality. The term multi-class means that the network provides different classes of service that can support diverse application requirements and heterogeneous users demand. This dissertation focuses on establishing an equitable price for each class of service in multi-class networks, considering fairness among the classes and economic efficiency. We adopt a game-theoretic approach to the problem in order to take into account the interdependence among users' service choices.We investigate subsidy-free prices for each class of service under two distinct service architectures: in multi-class priority-based networks, traffic from each class is assigned priority level in the queue; in multi-class DiffServ networks, network resource is allocated to each class. In both cases, classes of traffic having longer average waiting time receive monetary compensations from other classes and the subsidy-free price for each class of service is developed based on inter-class compensations. This work provides a framework to set subsidy-free price or sustainable price for each class of service which is assumed crucial to network providers if they are to survive the competition in the market place.We further consider market-clearing prices for each class of service in a competitive market in which each user endowed with an initial budget will purchase bandwidth from each class of the network resource to maximize his or her utility function. A competitive equilibrium is reached when the total bandwidth is allocated, each user spends all his or her budget, and the utility functions are independently and simultaneously maximized. Our research shows that such equilibrium always exists and, under fixed bandwidth supply for each class of service, the equilibrium is also unique. Furthermore, we discuss how to adjust the initial endowment of each user to meet his or her individual bandwidth constraint, either from constraint on the access network or from the limitation of the user equipment. Under this bandwidth constraint condition, the proposed competitive equilibrium yields the price for each class of service, the budget redistribution and the bandwidth allocation among all users. We also develop an iterative algorithm for budget allocation to satisfy each user's bandwidth constraint. The presented competitive market model provides a solution for pricing a multi-class network and allocating network resource among users. And we find this solution achieves higher social utilization, better individual satisfaction and the QoS of each class.Another advanced topic in communication networks is net neutrality, which has become the subject of fierce debate among the stakeholders of public telecommunication services. Broadband access providers argue that preservation of the integrity of the network services requires them to use discriminatory traffic management practices to slow down certain applications or to purge certain packets that would compromise the integrity of the network. We propose a solution based on the idea of inter-user compensations that could control network congestion and yet maintain fairness among heavy and light users without violating net neutrality. Users consuming less network resource will receive compensations from heavy users. Our research provides a method for broadband access providers to shape the traffic characteristics of users and thus controlling network congestion and maintaining network performance without inflicting discriminatory treatment on network traffic