WiMax Operator's Manual

CHAPTER 6
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Beyond Access
The previous chapter focused heavily on the physical infrastructure of the broadband
wireless network and how it is put in place. This chapter concerns itself with the higher layers
of the network having to do with the management of network traffic and the differentiation of
services. In other words, the focus is more on what the broadband wireless network has in
common with other high-speed access networks than on what sets it apart.
The Place of the Central Office in the
Business Case
Chapter 4 briefly discussed the physical requirements for a central office facility in terms of the
space itself. This chapter considers how the central office figures into the profitable administration
of the network, precisely what network elements are likely to occupy the space, and
how these elements relate to higher-layer networking functions.
The Role of the Central Office
Above all, the central office is a network hub—in point-to-multipoint networks it is a larger hub
aggregating the traffic of the smaller hubs that are the individual base stations. It is also the
point where the broadband wireless network connects to the public switched telephone system
(PSTN), the public Internet, and, in some cases, satellite networks. It can also connect to
remote storage networks, though as yet wireless broadband has played a small role in the storage
services industry.
The central office is much more than a relay point for inbound and outbound network
traffic, however. It is also generally a repository for customer records, including billing information;
the place where the entire operation is administered; the point where subscriber
authentication occurs; the nexus for service creation (that is, defining value-added services for
specific subscribers); the place where specialized content is cached and distributed; and the
home of any network security appliances in use in the operation.
Central Office Traffic Management and Distribution
As indicated earlier, wireless networks can utilize a number of transport protocols for handling
traffic to and from the subscriber premises and wide area networks (WANs), but the 802.16
standard is based on using Internet Protocol (IP). Given that, routing is the dominant traffic
distribution mode within the network.
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