Packetised wireless communication systems in interference limited environments
M.D. Orange · ResearchSpace (University of Auckland) · 1998
There is a strong likelihood that future wireless communication systems will employ packetised transmission techniques. Such an approach would provide a number of benefits, including the ability to integrate with emerging wired systems based on Asynchronous Transfer Mode (ATM). In addition, packet-based wireless networks would allow for diverse traffic types and in particular, speech and data traffic, to be integrated more readily. This thesis presents theoretical models and performance studies for various interference limited, packet-based, speech and data wireless communication systems. Two packetised random access protocols are considered for investigation, namely Slotted ALOHA (S-ALOHA) and Packet Reservation Multiple Access (PRMA). The S-ALOHA protocol is designed specifically for data traffic, whereas the PRMA protocol is optimised for speech traffic, with the ability to also cater for data traffic. Previously published research into S-ALOHA and PRMA has generally focused on the performance of these protocols in idealised single cell systems, free from cochannel interference. Previous studies have normally only considered simple signal propagation models that give little or no consideration to signal variability. A common assumption made in previous studies assumes that all packets involved in collisions with other packets are lost, while those packets received in the absence of other packets are received successfully. In this thesis, the performance of S-ALOHA and PRMA in more realistic multiple cell configurations, namely the outdoor cellular and in-building pico-cellular environments, has been considered. The fluctuations in received signal strengths have been modeled in this thesis using narrowband statistical propagation models. In addition, the assumption relating to packet collisions has been reconsidered in this thesis because practical receivers are often capable of locking onto one packet in the presence of other intra-cell and inter-cell interfering packets, due to the receiver capture effect. A capture probability model has been developed in this thesis, which defines the probability of a desired packet capturing the central cell base station in the presence of both intra-cell and inter-cell interfering packets. Accompanying Markov analysis theory has been developed to analyse the performance of multiple cell S-ALOHA and PRMA systems. Having developed the necessary framework, it has been possible to successfully analyse various multiple cell S-ALOHA and PRMA systems. These include a multiple cell data-only S-ALOHA system, multiple cell speech-only PRMA systems with and without selection diversity and speech packet retransmission and an integrated speech-data multiple cell PRMA system with selection diversity and speech packet retransmission.