As users expect better quality voice service and more features such as caller ID and call forwarding, etc. All of these changes are made to improve the quality of the service, add features, and serve more users on the system. The wireless industry has made projections on how they expect the rollout of technology to progress in the next few years, as shown in Table 2. Table 2 shows that the number of wireless service users is expected to nearly double. The Figure below shows a normal cellular area coverage scheme.
Base stations provide multiple channels that users gain access to, through their mobile phones.
The cells have overlapping coverage to provide redundancy and allow for handoffs as the user moves from one cell to the next. The Figure depicts perfect circular-signal coverage from the cell center. Normal cellular area coverage scheme, showing base stations. In order to predict the more realistic coverage, ITS and other research organizations are developing and evaluating propagation models that are more responsive to the needs of the cellular and private land mobile radio service providers for signal coverage predictions. Another common model is the Okumura-Hata model.