On the outage probability in single frequency networks for digital broadcasting

Abstract

The new digital modulation schemes (OFDM) proposed for broadcasting of sound and television allow for the use of simulcasting, i.e., letting all transmitters in a radio network transmit on the same frequency. Such single-frequency networks (SFNs) have the potential of providing good coverage and very good frequency economy in wide-area (nationwide) applications. An OFDM-based SFN is analyzed with respect to its coverage properties. The network performance is measured by the outage probability and frequency economy. Both wide and local area systems are considered. Results show that in wide-area networks, very low outage probabilities may be achieved with very modest transmitter powers. The main reason for this is the inherent diversity, the efficiency is of which is primarily dependent on the transmitter density. However, in local area systems with only a few transmitters in each region, the performance is shown to drop drastically, mainly due to the low degree of diversity. This work implies that good network planning results in low-power, closely spaced transmitters. >