Optimization issues in broadband networks

Broadband networks consist of various types of network architectures and protocol stacks. Next generation network (NGN) is an integrated broadband network infrastructure, unified by the an all-IP platform, which supports various new services such as IPTV, multimedia services, mobile commerce and many other emerging applications yet to come. The single IP platform also enables the convergence of fixed and wireless services (FMC). FMC leverages on the benefits provided by both network infrastructures, on one hand, the high bandwidth support provided by a fixed line networks(such as optical networks), on the other hand, the mobility support facilitates seamless service provision. In the dissertation, we first describe the following problems and suggested solutions, we present an overview of the problems we study in the dissertation. Moreover, we describe briefly the methodologies we adopt to address these issues. We investigate the network planning problem for a general wireless broadband overlay network. This framework has applications in wireless broadband access networks, such as WiMAX (Worldwide Inter-operability for Microwave Access). We propose an approximation algorithm which decides a minimum-cost BS-SS assignment of Subscriber Stations (SS) to Base Stations (BS). The assignment decides the traffic association relationship between each BS node (Server) and SS node (Client) pair. The objective is to find a minimum-cost subset of BS nodes which can support all traffic demands from SS nodes. We consider primal-based, primal-dual, and also greedy-heuristic approaches for special cases and obtain theoretical bounds on the worst-case performance of our algorithms, with regard to the optimal solutions. We present an optimal utility-based bandwidth allocation scheme for VoD services over an experimental integrated optical and wireless broadband network. We formulate the problem using integer programming, and propose an efficient dynamic programming approach to find the optimal solution. We present a centralized antenna resource allocation scheme which provides a nearoptimal solution for an experimental integrated optical/wireless infrastructure over MIMO links. We formulate the problem using integer programming, and propose an efficient algorithm using the hungarian algorithm. We compare its performance with other heuristics via simulations. The results show that our algorithm is able to achieve a desirable load-balancing effect, while maintaining a higher aggregate throughput, compared with the traditional solution without the centralized resource allocation scheme. We study the cost and performance issues involved in the design of a joint optical and wireless broadband network infrastructure. The Next Generation Network (NGN) may be regarded as a fresh broadband architecture that best utilizes and combines the major advances in optical, wireless, and computer communication networking of the past decade. Attractive business opportunities will be opened by the NGN, but cost-effectiveness in building and operating it remains a crucial challenge that can differentiate a profitable implementation strategy from one that is merely "hype". This chapter introduces a promising optical/WiMax architecture for Optical-Wireless Integration (OWI) and describes a cost model for this architecture that includes the more important cost issues. Results from initial use of this cost model compare OWI with other existing solutions for broadband access, showing superior cost-effectiveness for the OWI solution as well as the potential for further reducing capital and operating expenses. Besides the problems mentioned above, we also carry out a set of emulations on an typical optical/wireless broadband network platform. The result demonstrates a promising flexibility and convergence gain obtained from the integration of optical and wireless networks without undermining the network efficiency.