Co-ordination Between Broadband Fixed Wireless Access Systems in the 28 and 42 GHz Frequency Bands - Extended Study

Executive Summary

1. Study Overview

A further analysis has been conducted to supplement Section 3 of the original "Co-ordination between Broadband Fixed Wireless Access systems in the 28 and 42 GHz frequency bands" report (referred to hereafter as the original report). The analysis and the conclusions in the original report were based on a series of common assumptions reflecting existing standards and typical equipment and operational parameters. The purpose of this project is to modify some of these assumptions and to investigate the impact on the conclusions. Three specific aspects have been investigated:

• the effect of changing interference to noise ratio (I/N) from –10 dB to -6 dB on the analysis
• the impact of altering Base Station (BS) antenna downtilt on the analysis
• the impact of different cell sectorisation on the co-existence conclusions

2. Conclusions and recommendations

1. Boundary Power Flux Density limit for co-ordination

Our investigations have concluded that individual BFWA transmitters should be co-ordinated when the PFD generated at the network’s service area boundary exceeds the following values:

42 GHz: -95.5 dBW/MHz/m² (3 dBW/MHz/m² higher than the original limit)
28 GHz: -99.5 dBW/MHz/m² (3 dBW/MHz/m² higher than the original limit)

2. PMP Base Stations

For a PMP base station transmitter generating an EIRP of 0.5 dBW / MHz (= 15 dBW in 28 MHz bandwidth), these PFD limits correspond to maximum co-ordination distances from the service area boundary of:

42 GHz: 13.5 km (4.5 km smaller than the original limit)
28 GHz: 21 km (6.5 km smaller than the original limit)

These maximum co-ordination distances are those at which co-ordination will be required under free space propagation conditions and are functions of EIRP. These are also the minimum distances at which a base station receiver with a directly aligned line of sight path towards the network service area boundary and a 15 dBi gain antenna will be protected against interference from individual interferers in adjacent networks.

Without co-ordination, protection from interference at locations closer to the boundary will require a reduction in the antenna gain in the direction of the boundary, or additional path loss between the receiver station and the boundary.

3. Subscriber Stations (PMP and Mesh)

Where uplink ATPC is deployed, and assuming a maximum transmitter EIRP of 11.5 dBW / MHz, the maximum co-ordination distances from the network service area boundary for PMP subscriber stations and mesh network node stations are:

42 GHz: 7.5 km (2.5 km smaller than the original limit)
28 GHz: 12.5 km (3.5 km smaller than the original limit)

It is recommended that, to avoid interference from or between high density subscriber networks, operators in adjacent service areas should avoid co-channel, co-polar operation within 5 km of their network service area boundaries.

 4. Effect of multiple interferers

application of the I/N = -6 dB limits will ensure substantially interference free co-existence between adjacent service areas for both PMP and mesh architectures. Finally, this conclusion is valid regardless of the PMP network cell sectorisation deployed.

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