In this dissertation, we are concerned with a slotted packet code division multiple access (CDMA) system to efficiently multiplex various traffic at a wireless interface.
First, we propose a new packet Multi-Code (MC)-CDMA protocol
with a variable request pool (VRP) scheme. In the proposed protocol (E-Protocol), VRP has a varying number of codes for acc
ess requests on the vertical axis and a number of mini-slots on the horizontal axis, and the number of codes for access requests may be different from time slot to time slot depending on the number of mobile calls with transmission permission, and request packets in mini-slots are transmitted concurrently with the data (voice/video) packets of other calls during a time slot.
The proposed protocol preserves the good features of the original DQRUMA/MC-CDMA protocol, and can avoid severe collisions for access requests which may occur in the original protocol.
The efficiency of receiver utilization in a base station (BS) is also improved in the proposed protocol.
Unlike the E-Protocol, we previously proposed another protocol (P-Protocol) using a lattice pool for request accesses (LPRA) scheme,
which requires additional receivers relatively to the original protocol in order to reduce request collisions at a BS.
The structures of the receivers and their operations in the P-Protocol are simpler than for the E-Protocol.
There is little difference in performance between the E- and P-Protocols.
Thus, in configuring the cost-effective system, the E-Protocol is better than the P-Protocol.
Second, we modify the original DQRUMA/MC-CDMA protocol to accommodate
real-time and non-realtime traffic and call this the modified protocol (A-Protoc ol).
Useful features of the original DQRUMA/MC-CDMA protocol are preserved
in the proposed changes with the additional advantage of reduction
of the number of collisions during access requests, which may occur
in the original protocol.
We analyze a system model to analy...