Combined URN and TDMA scheme for multiple-access protocols

Local area networks provide communications facilities for high-speed data transfer between computers and erminals within a limited geographical district. The investigation of methods of improving the throughput-delay behaviour of such systems, even under heavy traffic conditions, is an open and challenging research area. A new family of hybrid multiple-access protocols is proposed for contention resolution in local networks. These protocols are a combination of random and deterministic multiple-access protocols. A dynamic frame construction is used. The frame consists of a status slot, followed by an RTDMA period and a URN period. This scheme provides stability under any circumstances and allows for control mechanisms so that good throughput-delay characteristics can be achieved. Analysis shows that the proposed protocols behave better than the isolated URN or RTDMA schemes, exhibiting low access time under normal traffic, while under heavy traffic, channel utilization remains high and the delay at acceptable levels.     

Performance of Integrated Packet Voice/Data Token-Passing Rings

This paper presents performance results that indicate that packetized voice service can be provided on a token-passing ring without adversely affecting the performance of data traffic. This is accomplished by introducing a relatively mild priority structure: stations are limited to a single packet transmission per medium access, and voice packets are given access priority over data packets at the same station. In addition, voice traffic is allowed longer packet lengths than data traffic. Several versions of this basic scheme are considered: 1) the number of active stations is constrained so that voice packets are guaranteed access within one packetization period, 2) no guarantee on access time is provided and voice packets are discarded when the waiting time exceeds one packetization period, and 3) no guarantee on access time is provided and voice packets are buffered until they can be transmitted.     

The no slot wasting bandwidth balancing mechanism for dual busarchitectures

A bandwidth balancing (BWB) mechanism has been added to the distributed queueing algorithm of the distributed-queue dual bus (DQDB) network. BWB can provide the requested throughputs by lightly loaded stations and evenly distribute the remaining channel bandwidth among overloaded stations. However, its operation requires the wastage of channel slots. The authors introduce a new bandwidth balancing mechanism for DQDB. The operation of the new mechanism requires one additional bit in the access control field (ACF) of the slot but has the advantage of exhibiting a similar behavior with the current BWB mechanism of DQDB without wasting any channel slots. For this reason, it can converge faster to the steady state in which fair bandwidth allocation is achieved. The authors investigate the throughput and delay performance of the proposed mechanism under one traffic class and examine its capacity to support multiple priority classes of traffic. They also compare its performance with the corresponding performance of the BWB mechanism of DQDB     

Delay analysis of various service disciplines in symmetric tokenpassing networks

An approach to the delay analysis of various service disciplines in symmetric token passing networks is presented. It is shown that exact or approximate accurate expressions for the average packet delay of different service disciplines can be directly derived by the delay expression of the exhaustive service system. This can be accomplished by inflating, by an appropriate factor, the packet size of the discipline whose performance is analyzed and then using the inflated packet in the delay expression of the exhaustive service system. The method is applied to the analysis of the limited service and TTS disciplines, and its accuracy is verified by simulation results. The advantages of the analytic method presented are its generality, higher accuracy over previous analytic methods, and insensitivity to network latency and other system parameters