Licence conditions variation support

UKBB were seeking support for a variation to their technical licence conditions.  They were seeking a relaxation of the base station and terminal block edge masks in ther licence from Ofcom to provide more flexibility regarding equipment.  The study undertook modelling of interference potential from base stations and terminals under various  block edge mask scenarios to support UKBB’s input to Ofcom.

The technical modelling focussed on the need or otherwise for guard bands between TDD & FDD Mobile WiMAX systems operating in adjacent spectrum blocks.  This was to help ascertain whether an additional frequency offset (corresponding to a guard band) should be applied to the block edge mask proposed for mobile terminals operating in the 3.5 GHz band. The assumptions at the time about the need for guard bands were largely based on the outcome of work undertaken by Motorola and reported to CEPT in document SE19(06)70. The Motorola modelling was based on a number of mobiles connected to networks operating in adjacent spectrum blocks and located in small traffic hotspot areas of 10–20 metres radius.

The modelling undertaken in the study assumed terminals based on the ETSI EN 302 326 standard for digital multipoint radio systems, using a 1x4x2 frequency reuse pattern (i.e. four-sectored cells and two available carrier frequencies). Various scenarios were analysed by varying guard bands and cell sizes . The results compared the impact on terminal signal to interference plus noise ratio (SINR) and spectrum efficiency (bits/s/Hz) under each scenario. The results of this modelling suggested that a guard band might be required in some cases, especially in the absence of co-ordination between adjacent block users.

The modelling made use of our in-house Systems Spectrum Engineering Toolkit (ASSET) platform. The output of the study was a report that could be used as input to Ofcom.