ime-varying channel gains, such as fading, are taken into account by adding some margin depending on the anticipated severity of its effects. The amount of margin required can be reduced by the use of mitigating techniques such as antenna diversity or frequency hopping. An abstract description of the link budget in any direction (downlink/uplink) has the following form: [8] Received Power (dBm) = Transmitted Power (dBm) + Gains (dB) - Losses (dB) (12-1) 12.1 Definition of the performance metrics Link budget evaluation is a well-known method for initial cell planning that needs to be carried out separately for downlink and uplink. Although the link budget can be calculated separately for each link, it is the combination of the links that determines the performance of the system. Using the margins in the link budget, the expected signal-to-noise ratio can be evaluated at given distances. Using these results, the noise limited range can be evaluated for the system. The typical link budget parameters are given in Table 12-1. Although a user may be sufficiently covered within certain areas of a cell for a given service, when multiple users are in a cell the radio resources (time, frequency, space, power) are shared among the active users. It can be expected that a user's average data rate may be reduced by a factor of N when there are N active users, assuming resources are equally shared among active users, and there is no multi-user diversity gain, relative to that of a single user. Therefore, any coverage assessment for any particular service must be coupled with the number of active users in the cell and their associated quality of service requirements. If users with poor channel conditions are provided with more radio resources, it would adversely impact the total cell throughput. Thus, there is a trade-off between coverage and capacity. The performance metric that is typically used is the number of admissible users, parameterized by the service minimum bit rate, maximum tolerable latency, permissible outage proba