Extra 56MHz Channel In The 28GHz Exclusive FS Allocation

Date: 28th April 2000

Use of an "extra" 56MHz paired channel in the 28GHz Band

Introduction

At the last Consultative Group meeting the RA presented the proposals to issue licences in the 28GHz band for BFWA in three equal packages in a number of regions. The spectrum packages are paired blocks of 2x112MHz arranged on the 27.5-29.5GHz band CEPT channel plan in a manner consistent with developments regarding the anticipated ERC Decision for FS/FSS use of the band.

Developments with the draft ERC Decision have resulted in the possibility of an "extra" 56MHz paired channel being available to the Fixed Service in the FS exclusive part of the 28GHz band.

The Technical Sub Group has discussed this "extra" channel and sees a number of possibilities for its use.

This "extra" channel is subject to approval of the ERC Decision relating to geographical band segmentation in the 28GHz band.

Option1

One use of this channel could be to insert a "hard" 28MHz wide guard band between the 112MHz licences to help reduce some of the co-ordination issues between operators and provide at least some minimum level of protection.

There was a fair amount of support within the Technical Group for this approach which could have a number of advantages:

	Some degree of protection is provided between operators providing a level of comfort.
	Amount of inter-operator co-operation needed is reduced.
	Greater capacity within the licensed bands for coping with co-ordination difficulties.
	The operator in the centre 112MHz block is less constrained by the need to co-operate with competing operators at each end of the assignment.
	Some studies suggest that a guard band equivalent to one channel width reduces the interference problems (same area, adjacent frequencies) to a negligible and predictable level. This may be as low as 1-3% of total cell area and being predictable can be planned for by the operator.

Some members considered this use as wasteful. However, it may be argued that this is not necessarily true as this has to balanced against the potential greater use of the licensed blocks that can be made as a result . In order not to appear wasteful of spectrum these 28MHz channels could be considered as "edge channels" as defined within the CEPT SE19 co-existence work. This means that they could be used for deployment subject to close inter-operator co-operation perhaps at a later date.

Option 2

Alternatively these guard bands in Option 1 could be split in two and added to the 112MHz assignments. This would increase the assignments to the operators at each end by 14MHz and the operator in the middle by 28MHz.

Although on paper this appears to make full use of the "extra" spectrum, some operators expressed concern with increasing the size of the assignments over 112MHz.

 Option 3

A further option discussed was to leave the "extra" 56MHz unassigned and as spare capacity in case of difficult co-ordination problems which could be assigned on case by case basis when justified. This may be difficult to implement from the point of view of deciding who gains access to this channel and the need for further guard bands depending on which operator gains access.

Option 4

Finally the possibility of using this "extra" channel as a further channel for assignment to an operator requiring only a narrow assignment was highlighted. Depending on the positioning within the band this could increase the co-operation burden on one other operator if at the end of the band. If placed between two operators their burden would remain unchanged except that they might need to protect narrower systems in this extra assignment. One would also need to question how much spectrum might be fully useable in this extra channel bearing in mind the implied inclusive guard bands.

Appendix 1 illustrates these options.

Group considerations

Having considered these options, the group majority was in favour of Option 1.

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