What is the general formula of dropped call rate? Explain?

General formula of dropped call rate

The general formula of dropped call rate P in a whole system can be expressed as:

1. z1 and z2 are two events, z1 is the case of no traffic channel in the cell, z2 is the case of nosafe return to original cell. Assuming that z1 and z2 are independent events, then

2. (1 − β) is the probability of a call successfully connecting from the old BSC to the MSC. Also, (1 − β) is the probability of a call successfully connecting from the MSC to the new BSC. Then the total probability of having a successful call connection is

3. The call dropped rate P expressed in above Eq can be specified in two cases:

1. In a noise limited system (startup system): there is no frequency reuse, the call dropped rate PA is based on the signal coverage. It can also be calculated under busy hour conditions.

2. In an interference-limited system (mature system): frequency reuse is applied, and the dropped rate PB is based on the interference level. It can be calculated under busy hour conditions.

In a commonly used formula of dropped call rate, the values of τ , θ, and β are assumed to be very small and can be neglected. Then