* for both TDD and mixed TDD/FDD system deployments

** a full interference LOS is assumed

*** note that guard distances are expressed as distances between the area boundaries

**** Hub = Central Station

NOTE 7: Two scenarios are analysed by the report:

• The result of the downlink (hub to terminal) scenario is a guard distance estimation of about 20 km.
• The result of the uplink (terminal to hub) scenario is a guard distance estimation of about 55 km. The different result in respect to the above downlink scenario is due to the possibility of no rain attenuation correlation. This guard distance can be reasonably reduced to 40 km, taking into consideration the earth bulge (obstruction effect inside the 1st Fresnel ellipsoid due to the earth curvature) at typical antenna tower heights (e.g.30 m).

It is worth noting that the occurrence probability of the rain uncorrelation interference scenario in the uplink case is quite low ( according to the ISOP method). This can suggest Therefore the alternative adoption of 20 km as a reasonable minimum guard distance can be suggested.

"The European conference of Postal and Telecommunications Administrations,

considering

1. that within CEPT the use of the band 24.5 - 26.5 GHz along with other bands has also been identified as a suitable band for the implementation of Fixed Wireless Access systems (ERC/REC/13-04xyz).
2. that Fixed Wireless Access Systems in the range 24.5 - 26.5 GHz are expected to provide telecommunication services to the user with capacity requirements of up to several Mbit/s, carrying e.g. circuit –or packet-oriented traffic;
3. that within CEPT/ERC several administrations have introduced or will introduce also Point-to-Point fixed links in the band 24.5 - 26.5 GHz, following the channel plan recommended in ERC T/R 13-02;
4. that FWA in this band has substantial potential to enhance the availability of telecommunication services, particularly in urban and suburban areas;
5. that sufficient capacity and flexibility for deployment of multiple systems within a desired service area can be achieved by the aggregation of contiguous frequency slots from a homogeneous pattern;
6. that it would be beneficial if such a homogeneous pattern can be made compatible with the channel plan proposed in ERC-Recommendation T/R 13-02 for fixed service;
7. that the slot size considered for the deployment of FWA in order to satisfy the needs of the operators is 28 MHz in each duplex subband, which would be in line with ERC-Recommendation T/R 13-02;
8. that operators may advantageously deploy equipment with a variety of central frequencies and bandwidths within their block 28 MHz assignment to meet their operational needs;
9. that both time division duplex (TDD) systems and frequency division duplex (FDD) FWA systems could be accommodated, provided that appropriate co-existence criteria are met;
10. that to ensure coexistence between systems operating in the same area and in the adjacent frequency blocks, guard bands would have to be introduced between neighbouring FWA systems;
11. that the estimated size of the guard band needed is equal to the greater channel used by the two neighbouring systems;
12. that through appropriate regulations and co-operation between neighbouring operators the size of the guard bands could be reduced;
13. that guidance material is available to assist administrations with the assignment of frequency blocks to operators for fixed wireless access systems (see ERC/Report xx and yy).
14. that to ensure coexistence between systems operating in the same frequency blocks but neighbouring areas, separation guard distances would have to be introduced between neighbouring FWA systems;

noting

1. that the number of 28 MHz slots required by a system to provide service will depend on the channel width and cellular structure; it is expected that a minimum of 1 or 2 slots would be required;

recommends

1. that those administrations planning to implement FWA in the band 24.5 - 26.5 GHz, or parts of this band, should assign frequency blocks comprising slots aligned with the 28 MHz channel raster identified in T/R 13-02;
2. that the minimum number of 28 MHz slots assigned to an operator should be 1 or 2 (see noting 1);
3. that in the case of deployment of FDD systems the upper subband should be used for the transmission from the terminals to the central station (hub) and the lower for the transmission from the central station to the terminals;
4. that in the case of systems operating in adjacent frequency blocks in the same area, adequate inter-assignment protection should be ensured through the introduction of guard bands between neighbouring block assignments; such guard band may be explicit outside the blocks allocated to the operators or included within such blocks;
5. that the size of the guard bands to ensure adequate inter-assignment protection of FDD systems should be at least equal to 28 MHz (NOTE 1, NOTE 2); the guard band may consist of one unused slot of frequency, or of slots used only with one polarisation, adjacent to slots used on the opposite polarisation (see the figures in annex 1);
6. that, for deployment of TDD systems alongside TDD or FDD systems, the guard band should be when TDD systems are accommodated, the size of the guard bands to ensure adequate inter-assignment protection of TDD and mixed TDD/FDD systems should be at least equal to 2x28 MHz (NOTE 1, NOTE 2);
7. that, when TDD systems are accommodated and the size of the guard bands is 1x28MHz, a TDD hub must be at least 500m from any other hub;
8. that those administrations intending to leave to the neighbouring operators the responsibility of the inter-operator protection required by Recommends 5, 6 or 7 should consider adequate increased spectrum requirements (as specified in Recommends 4) within the assigned blocks (see annex 2);
9. that administrations may encourage co-operation between neighbouring operators in neighbouring frequency blocks and the guard band could then be considered as an "edge" band: this means that guard band may become usable by the operators by the means of mutual co-ordination involving in particular co-site or near site sharing and co-ordinated cell planning;
10. that in the case of systems operating in the same frequency block in neighbouring areas, adequate inter-assignment protection should be ensured through the introduction of reasonable guard distances between the boundaries of the neighbouring assignment areas where the same frequency block has been assigned; the size of guard distance should be chosen so that there is a minimum distance of 20 km between central stations and terminals and 40 km between central stations of neighbouring systems. (For further information on required and reasonable guard distances see section 5 of the ERC-Report xx), for FDD systems, at least 20km; when TDD systems are accommodated, the size of guard distance should be at least 40km;
11. that administrations encourage co-operation between operators in the same frequency block in neighbouring areas to reduce the size of guard distances through co-ordinated deployment and advantageous use of specific topographical or operational detail.

NOTE 1: that if an alternative pattern based on 3.5, 7 or 14 MHz slots is envisaged in some portions of the band, then the appropriate inter-assignment guard band is has to be evaluated on a case by case basis.

NOTE 2: that administrations facing the introduction of systems using channels broader than 28 MHz (e.g. 56 MHz) should take into account that the relative guard bands should be enlarged proportionally.