Application-Specific Equipment for the Central Office

Directing network traffic is the primary function of the central office, but it is far from the
only function. The central office also houses equipment that supports specialized services
and applications.
What this equipment will be depends on the suite of services the operator has elected to
offer. I have discussed some of the value-added services in Chapter 3, including mobile voice, conferencing, telemetry, storage, and entertainment multimedia content. One can envision
further applications, including interactive video commerce, such as has been done to a limited
extent in some European broadband networks; Web hosting, which is normally the function of
large specialized ISPs; Web mirroring, a subset of the latter; and so-called walled-garden content
that generally consists of local advertising and news items, which are not available over
the public Internet.
Conferencing equipment requirements vary according to whether the conferencing takes
place over IP, ATM, or Integrated Services Digital Network (ISDN). ATM-based video conferencing
has been the gold standard for the industry, but it is expensive to support, both for the
subscriber, who requires a special hardware component, and for the service provider. ISDN is
an obsolescent data standard that was commonly used for videoconferencing services in the
past despite the fact that it is expensive and difficult to administer. The trend today is to
migrate toward IP.
IP conferencing may involve special dedicated hardware components or simply software
installed in the subscriber’s computer. When it is offered as a fully supported service by a
broadband access provider, it usually involves not one but several dedicated hardware
components.
A complete discussion of conferencing will follow in Chapter 7. Here I will deal only with
the central office requirements for the service.
In an IP videoconferencing implementation within the central office, the service provider
will normally purchase equipment that can also be used for ordinary IP voice telephony; in
other words, it will be dual use. A gateway—generally occupying a separate computing platform—
will mediate between the metro network and the WAN and in most current equipment
will allow a video conference to take place across protocols. In other words, the individuals in
the broadband wireless network using IP-based equipment can conference with someone in a
remote location having only an ISDN connection. A separate component called a multiconferencing
unit (MCU), which is a kind of specialized switch that allows any number of callers to
participate in the conference, is necessary when more than two parties are involved. Finally, a
gatekeeper handles the administrative functions associated with the conferencing session,
including billing. The gatekeeper software may have its own dedicated computing platform or
may simply be a blade in a server running other operations support systems (OSS) software.
To maintain high image and sound quality, the IP transmissions must take place over a
network that is MPLS enabled from end to end. Thus, the broadband operator will have to put
in place agreements with long-distance service providers that will ensure that such arrangements
prevail.
Videoconferencing is a rare offering among wireless broadband operators, but it is within
the capabilities of an 802.16 network. In my view it is an attractive value add that will be
increasingly in demand in the future.