Capacity analysis of a PMR system with DAB downlink

Abstract

Several trunked private mobile radio (PMR) systems have been designed over the last decade, most of which have symmetric downlink and uplink channel capacities. These systems may not be spectrally efficient in case of group or broadcast-based voice and data calls, a common feature of PMR systems. We propose a new asymmetric PMR system comprising a wideband OFDM-based downlink and a narrowband uplink, which not only achieves a better spectral efficiency but also can support high bit rate multimedia applications. The system is shown to have high trunking efficiency since all users are assumed to use the pool of channels available in the wideband downlink. In this paper, we study the performance and capacity of a private mobile radio system using a digital audio broadcasting (DAB) downlink. In particular, we study the efficiency of such a system for voice calls using voice activity detection and statistical multiplexing. Moreover, we show that, the efficiency of the system can significantly increase, if the incoming calls, which can not find an available channel, are allowed to wait a certain amount of time before occupying a channel. © 2003 IEEE

A Spectrally Efficient PMR System Utilizing Broadcast Service

“…In order to find the number of cells, considering the carrier to interference ratio, appropriate cluster size should be calculated which is applicable to both systems. When hexagonal cells are assumed to be used and the service area is assumed to be flat, cluster size is determined from the desired carrier to interference ratio from the following formula [12]; (10) where , , and stands for cluster size, path loss exponent and number of interferer cells respectively. The cells, which contribute to interference significantly in an un-sectored cellular system, are the six co-channel cells in the first tier [12], [21].…”

“…Such systems are asymmetric, which have higher data rates at the downlink. Proposals have been made in which personal access communications systems, GSM and UMTS, are complemented with Terrestrial-Digital Audio Broadcasting (T-DAB) [9], [10] and DVB-T [11]. In these studies broadband downlink is used only for multimedia applications, and voice calls are carried by the narrowband channels.…”

“…The standard method for increasing spectrum efficiency in a cellular PMR system is frequency reuse [12]. The a-PMR architecture benefits from trunking efficiency [10] in the downlink and frequency reuse can only be employed in the uplink part. This architecture may not be efficient if the number of cells in the system is increased.…”