This study considered the feasibility of co-channel co-existence between IMT and DTT systems operating in the 470 – 694/698 MHz band. The study focussed on the impact of interference from IMT into DTT systems. Due to relatively high antenna gains, EIRP values and fixed antenna masts positioned above the clutter, the protection of DTT receivers from IMT base station (BS) interference was assumed to be the key issue to investigate in this context.
A review of relevant reference documents was conducted to establish IMT BS transmitter and DTT receiver modelling parameters and sharing criteria. This was followed by the interference analysis based on a number of sharing scenarios developed during the course of the study. SEAMCAT was used to undertake the modelling.
In this short study the feasibility of co-channel co-existence between IMT and DTT systems operating in the 470 MHz – 694 / 698 MHz band was examined. The aim of the interference analysis was to assess the impact of aggregate interference from IMT BS transmitters into DTT. The analysis used SEAMCAT (a Monte Carlo analysis tool developed within the frame of the CEPT) to undertake the modelling.
SEAMCAT (the analysis tool developed within the frame of the CEPT) Monte Carlo simulations were implemented for an assumed set of separation distances between the edge of the IMT cluster and the edge of the DTT coverage area by varying the location of the receiver within the DTT coverage area as shown below.
In each Monte Carlo trial, the DTT wanted power and the aggregate IMT BS interference power were calculated at the DTT receiver. Calculations were repeated over a number of trials and the resultant C/N+I statistics were compared against the co-channel protection ratio to determine the probability of interference within the DTT coverage area.
The output of the study was used to develop a draft GSM Association input into the ITU JTG 4-5-6-7 meeting in February 2014 in respect of the WRC-15 agenda item 1.1.