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In the view of the third generation of mobile systems, how to
increase the system capacity under limited bandwidth becomes
an increasingly considerable issue, in which the multiple access
technique is a key point of designing an efficient wireless
communication system. Goodman and Wei proposed a PRMA
protocol based on the packet reservation of slotted ALOHA. By
the use of the speech activity detector, PRMA utilizes the
channel bandwidth more efficiently. However the
contention-type multiple access scheme leads to bandwidth
wastes in the sense that several packets may collide together,
and the system is unstable since the throughput would shrink to
zero at heavy load. Thus Wen and Wang introduced a modified
protocol, named NC-PRMA (Non-collision PRMA). The NC-PRMA
protocol uses separate control channel and information
channel to centrally control the packet transmissions which can
eliminate the collision problem and instability issue in PRMA
and hence raise the system capacity. In this thesis, the
further studies of NC-PRMA adopting fast speech activity
detector (SAD) under different duplexing schemes (FDD and
STDD), as well as the multi-channel structure are
respectively investigated. Then a new proposed scheduling
algorithm is applied to the NC-PRMA system, that is SNC-
PRMA (Scheduling NC-PRMA). In the SNC-PRMA system the base
station (BS) dynamically allocates the packet transmissions
without a fixed frame-reservation mechanism, hence the channel
utilization is more flexible and efficient. From simulation
results, we observe that SNC-PRMA obtains performance
improvement compared to the original NC-PRMA. Especially
for the system capacity term, with the service quality
constraint of packet dropping rate being less than 1%, numerical
results indicate that the system can support 40 (45), 46 (51)
simultaneous conversations respectively under the FDD and STDD
schemes if slow (fast) SAD is adopted. In addition, SNC-PRMA
with multi-channel structure is also explored in this thesis.
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