Spectrum Sensing in Relation to Distributed Antenna System for Coverage Predictions

Distributed Antenna Systems (DAS) is one of the most promising ways of network deployment now-a-days. Mostly it is used in indoor environment for shopping areas and office locations. Here the Outdoor application of DAS, where multiple service providers can install their Base Transceiver Station (BTS)/Nodes at one location known as BTS hotel and the antennas are distributed all over target area by fiber optic network, is discussed. The very concept of splitting Base Station (BS) from its antenna system and putting it at one location (BS Hotel) and distributing antenna as nodes (Remote Unit, or RU) that can be easily mounted on any pre-existing support structure that may be a street furniture like public or private street poles, hoardings, facilities or even Shop Display Frame, is very attractive in its own way. The ease of installation, high utilization of network resources, multi technology adaptability, efficient energy usage etc. make O-DAS (Outdoor-DAS) network very lucrative. However, for an O-DAS network with large distribution of Remote Units, it is required to have complete knowledge of the spectrum environment at all the locations of remote unit for understanding actual coverage predictions and network health at every corner of network. In the event of deployment of O-DAS, spectrum sensing in the frequency band is one of the prerequisites. In this paper we have given basic concepts about O-DAS, its deployment and the spectrum sensing measurements carried out in GSM 900 frequency band. The band occupancy measurements have been carried out in 935–960 MHz band at a selective location in Delhi (India). In this paper it is shown that how an O-DAS network can become a boon for future technologies that need radiating sites at a low inter-site distance, by having a sensing capability at its nodes. An operational service provider is chosen for research purpose and improvements by implementing suggestions are presented.