 to be closer to their base stations. In the case of a pure fan-out network without a major backbone, this can reduce backhaul costs sig- nificantly. Also, having distributed MSC locations avoids having a single point of fail- ure for the entire wireless telephone system. This is only partial consolation for the ser- vice provider because having one MSC fail still takes all the base stations that supports out of service. For MSC locations, we are looking for places that are central in the transport net- work for base stations, PSTN, PPDN, private networks, and signaling. Where there is a cheap backbone transport network, this becomes less important than the availability of real estate and electrical power. Where there is no backbone, or where the backbone has no extra transport available for a wireless service provider, we have to do some se- rious MSC location planning, scouting locations, evaluating transport costs, and find- ing the locations for MSCs that minimize transport costs. The planning process also should have an eye toward the future. A system with three MSCs is expected to grow and will require a fourth and a fifth MSC over time. The MSC plan should take into account the space, power, and transport requirements of future switches as well as the present ones. The MSC location process is done when there is a clear decision where to put the MSCs for the system, whether they should be colocated or separated, and how their power and transport needs will be met. Further, there should be a clear plan as to where future MSCs will be located. 34.3 Equipment Provisioning for MSCs There are many components of the MSC in a wireless telephone system. The individ- ual vendors and equipment will determine the specific MSC equipment needed, but we can go over some of the basic issues here. 20 the United States and western Europe, any city or large town has a telephone transport backbone. There may not be such a thing in more remote parts of the world. Downloaded from Digital Engineering Library @ McGraw-Hill (www.d