Limitations in Wireless Networking
With the local, fixed telephone network, where all end-users are static, a wireless communications system is extremely complex.
- First, the wireless network requires an air interface between base stations and subscribers to provide telephone grade communications under a wide range of propagation conditions and for any possible user location.
- Each of these base stations must be connected to the MSC.
- The MSC must eventually provide connection for each of the mobile users to the PSTN.
- A central office (CO) telephone switch may handle up to a million landline subscribers simultaneously; the most sophisticated MSCs of the mid 1990s are only able to handle 100,000 to 200,000 simultaneous cellular telephone subscribers.
- A problem unique to wireless networks is the extremely hostile and random nature of the radio channel, and since users may request service from any physical location while traveling over a wide range of velocities, the MSC is forced to switch calls imperceptibly between base stations throughout the system.
- The radio spectrum available for this purpose is limited, thus wireless systems are constrained to operate in a fixed bandwidth to support an increasing number of users over time.
- Wireless systems grow; the necessary addition of base stations increases the switching burden of the MSC.
- Because the geographical location of a mobile user changes constantly, extra overhead is needed by all aspects of a wireless network, particularly at the MSC, to ensure seamless communications, regardless of the location of the user.