Integrated voice/data services on a plastic optical fiber local area network

Abstract

An integrated voice/data services local area network access protocol designed to work efficiently over a plastic optical fiber slotted ring is described. The proposed control mechanism ensures that delays to time-critical voice service are bounded and that synchronous transmissions are kept during speech active periods. An adequate network architecture is described. Analytical models for the voice traffic and for the data traffic are utilized for the performance evaluation of a local area network using the proposed access mechanism and network architecture. The performance of the modified Cambridge Ring Access Mechanism (mCRAM) was analyzed for the cases of voice traffic only and data traffic only. For the voice traffic, a simple binomial model for the steady-state probability distribution of the number of active voice sources has been used. The analysis indicates that the efficiency of slot utilization can be improved with negligible effect on speech quality. The adapted cyclic server model of H. Takagi (1986) has been used for determining the message delays in mCRAM for data traffic. It is shown that mCRAM is able to perform well over a wide range of stations and transmission rates. >