ABSTRACT
CONTENTS 8.1 Introduction ............................................................................................... 147 8.2 802.16 Time Division Multiple Access ................................................... 150
8.2.1 802.16 Physical Layer ................................................................... 150 8.2.2 TDMA Framing and Transmission Timing ............................... 151 8.2.3 Transmission Scheduling in the Logical Channels .................. 154
8.2.3.1 The Basic Channel ......................................................... 154 8.2.3.2 Distributed Election Scheduling Broadcast
Channels ......................................................................... 154 8.2.3.3 Tree-Based Scheduling Broadcast Channels .............. 157 8.2.3.4 Best Effort Broadcast Channel ..................................... 158 8.2.3.5 Transmission Scheduling in the Data Channels ........ 158
8.2.4 Network Entry and Synchronization ........................................ 161 8.3 802.16 Mesh Networking ......................................................................... 162
8.3.1 802.16 MAC Connections ............................................................ 162 8.3.2 Mesh Network Addressing ......................................................... 164 8.3.3 QoS-Aware Convergence Sublayer ............................................ 165
8.4 Network Security ...................................................................................... 168 8.4.1 Network Authentication .............................................................. 168 8.4.2 Backbone Hop-by-Hop Security ................................................ 169 8.4.3 User End-to-End Security ............................................................ 170
8.5 Conclusion ................................................................................................. 171 References ........................................................................................................... 171
Wireless mesh networks interconnect access points (APs) spread out over a large geographical area. Wireless terminals (WTs) connect to the APs on
and
their first hop. Then, their traffic is carried by the wireless mesh to the pointof-presence (POP) where it can go to the Internet (Figure 8.1). The POP is the only node in the network connected to the Internet and can act as a base station (mesh coordinator). In urban areas, mesh networks interconnect wireless hot spots. Mesh networks decrease the cost of running the hot spots since they only require a single POP broadband connection for the whole network. For example, using a mesh network to interconnect 133 existing hot spots in the Toronto downtown area would decrease the total cost of running the hot spots by 70% [1]. Mesh networks can also be used to provide the wireless last mile in rural areas where it is impractical to provide wired connectivity due to sparseness of customers. This is the idea behind rooftop networks [2], where each house has a mesh node connecting it to neighboring houses while providing wireless access to the devices in the house.
