Management, Monitoring and QoS in Multi-cell Centralized WLANs

Introduction

The notion of Mobile Internet relies on scenarios where mobile users may have access anytime and anywhere to conventional and emerging Web applications requiring multimedia and interactive communications. Wireless access networks are the key element to implement these scenarios and much work has been done in recent years to develop and improve wireless technologies, including the introduction of support for mobility and Quality of Service. In this respect, special interest has been paid to wireless local area networks (WLANs) based on the IEEE 802.11 standard (I.S. 802.11, 2007), that exhibits characteristics useful to pursue the goals of the Mobile Internet, including a large number of installations in a wide range of contexts.

Three main trends have emerged in the last years in the evolution of wireless access networks. The first one is the deployment of large access networks based on wireless technologies, with the aim of providing uniform coverage and connectivity to wider areas. This aim has been pursued either by the installation of new large access networks, or by integrating existing networks in a single administrative federation. A major problem in this respect is the lack of standard configuration tools to manage the access network, and the consequent need for inter-operable solutions. A second trend is the integration of networks based on heterogeneous technologies to enhance connection opportunities. The most cited case is the integration of cellular data networks with IEEE 802.11 WLANs. This trend has triggered much research effort in the area of mobility management, specifically vertical hand-off among heterogeneous networks, and in the area of adaptive behavior to variations of network conditions. The third trend is the enhancement of the service provided by wireless access networks with the introduction of features like security, fast and transparent mobility support, quality of service, access control, accounting, etc.

In this chapter we discuss how the introduction of a network management protocol specifically designed for wireless networks can be of help in pursuing the above goals. To this end, in the rest of the chapter we describe the current proposal for the CAPWAP protocol and its current implementations, together with its utilization as a tool to monitor and manage wireless access networks. An attractive feature of this approach is that the resulting schema can be considered as a framework in which specific solutions to individual problems can be integrated to provide a global enhancement in the functionalities of wireless access networks.