The proposed model takes into account that in IEEE
802.16 MAC based systems there is no packet capture. This
is due to the fact that subscriber stations always transmit
with the minimum transmit power to achieve a specific Bit
Error Rate (BER) at the base station. This policy avoids cochannel
interference with other cells. Consequently, when
two o more stations transmit a bandwidth request in the
same contention minislot, a collision occurs and it is not
possible to recover any of the bandwidth requests. Our
model is based on a few assumptions. The system is
considered to be operating in steady state and it is
considered that all active SSs are continuously backlogged.
It also makes use of a constant value to represent the size of
the backoff window of the Exponential Backoff Algorithm
(EBA) as we will explain in Section 4.