Trunked Mobile Radio Systems Research Articles

Traffic-Aware Joint Allocation of Uplink Control and Communication Channels in Multicast Systems

In multicast wireless access systems such as a trunked mobile radio system, channel allocation is performed based on multicast groups instead of radio units. Thus, in these systems, the call source units are these groups, which we also call the users . In a practical system, these users are finite in number, and each user or group may consist of many radio units. In this paper, we discuss the coupling of uplink control and communication segments (layers) of such finite source systems, in which the performance of one layer directly affects that of the other. The conventional studies model these system segments separately and, thus, are unable to capture the coupling issues in networks with the finite sources' constraint. We first propose a novel model that incorporates this coupling by jointly quantifying both the collision loss at the control layer and congestion loss at the communication layer. Under our proposed framework, we further optimize the number of uplink control and communication channels to minimize the joint total loss rate given a constraint on the total number of available channels. In addition, we demonstrate the capability of our proposed model in estimating the invisible actual traffic load and provide guidelines for developing an algorithm for the traffic-aware allocation of channels, based on the proposed model.

Analysis of Public Safety Traffic on Trunked Land Mobile Radio Systems

Mobile radio systems for public safety and agencies engaged in emergency response and disaster recovery operations must support multicast voice traffic. In this paper, we analyze the distribution of call interarrival and call holding times for multicast voice (talk group) traffic on a transmission trunked mobile radio system. In such systems, the channel is held only while a user is making a call (while the push-to-talk key is pressed and the radio is transmitting). We find that the call interarrival time distributions are exponential and exhibit tendency toward long-range dependence. The call holding times best fit lognormal distributions and are not correlated. A potentially important implication of these findings is that performance estimation methods that assume memoryless Markov arrival and departure processes may not be viable approaches.

Comparative analysis of the standards for digital trunked mobile radio systems

For building Private Mobile Radio (PMR), analogous and digital trunked mobile radio systems are used today. Due to many advantages, trunked systems of digital mobile radio are gradually pushing out analogous trunked systems. Digital trunked systems are produced and built in the field, according to specific standards. The most famous and spread standards of the world are "EDACS", "TETRA", "APCO 25", "TETRAPOL" and "IDEN". A short description and characteristics of the above mentioned standards are given in the paper, as well as their comparative analysis.

M/D/C queue with priority: application to trunked mobile radio systems

A procedure is presented for estimating the mean waiting time in an M/D/C queue with two levels of nonpre-emptive priority. The approximation gives a maximum relative error of 10% for heavy load and is greater than the simulated results. This makes the procedure useful for evaluating trunked radio systems.

Simulation study of a signalling protocol for mobile radio systems

An essential component of any trunked mobile radio system is the signalling protocol used for the purpose of call establishment. The paper presents computer simulation results of one such protocol designed for use with dedicated signalling channels and incorporated within the Advanced Mobile Phone Service. The latter is a high-accuracy cellular-structured mobile radio system currently being implemented by AT & T in Chicago, Illinois. In particular, the paper examines the signalling channel blocking probability, the effect of varying system parameters on this blocking probability and the mean delays encountered in obtaining a signalling channel. Also of concern is the influence of the signalling protocol on the subsequent voice-channel blocking probability. To this end, a fixed voice-channel assignment scheme and an Erlang B service discipline were included in the simulation model. It is determined that if two or more automatic reattempts to gain access to the system are permitted, then only one signalling channel per cell is required in order to maintain the signalling-channel blocking probability below 2% for all traffic loads likely to be encountered in practice.