Numerical and Simulation Results
For single slot service, the results from the approximation and
simulation are presented, but for multiple slot service, only
results from simulation are given.
In the numerical calculations and simulations, 4 carriers, i.e.,
4x8=32 channels in a cell are assumed, from which 1 channel
is reserved for GPRS data and 31 channels are shared by
circuit switched services and GPRS. In the simulations, when
a new circuit switched call arrives, if no free channel is
available and the number of circuit calls in service is below
31, one of GPRS calls is stopped its transmission in order to
allocate one channel to the new circuit call. When resources
are available, the interrupted GPRS calls have higher priority
to be allocated resource than the queueing calls. The average
interruption time and probability of interruption are simulated.
The average service time of circuit switched services is
exponentially distributed with a mean of 180 s. This traffic
load of circuit services is 22.83 Erlang corresponding to 2%
blocking probability for 3 1 channels. The maximum number
of GPRS users allowed into network is 40.