1. A methodology for establishing national frameworks for spectrum sharing between MFCNs and FSS/FS in the GHz band
20 April 2015

2. Contents Summary Spectrum sharing framework
Operational guidelines and calculations

3. Summary
This contribution proposes a methodology for establishing a spectrum sharing framework by means of identifying a toolbox of options which administrations will be able to adopt as best suited to their national circumstances.
A spectrum sharing framework can be understood as a set of sharing rules, and its development will require the involvement of all relevant stakeholders.
Such rules can be incorporated in the relevant national technical licence conditions, as is common practice today, and will also define procedures to be followed during the roll-out stage of the MFCN networks.

4. Summary Sharing framework is based on the following principle:
Regulators would specify the criteria for the protection of the incumbent users (FSS/FS) in terms of the maximum permitted interference at the input to the FSS and FS receivers.
These limits would then be used to calculate (as specified by the regulator) the maximum permitted power (EIRP) to be radiated from any given MFCN base station sector.
No specific values or value ranges are proposed for the various technical parameters involved in the calculations. These will be the subject of future contributions.
There is always a trade-off between the simplicity of a spectrum sharing framework and spectrum sharing efficiency. The proposed methodology is intended to provide the flexibility for administrations to exploit this trade-off.

5. C/(N+I) – “link aware” criterion
Summary
Protection criterion:
C/(N+I) – “link aware” criterion
has potential for more efficient spectrum sharing
can be used when link budgets are known
I/N – interference based criterion
is more conservative and therefore can be overprotective
can be used when link budgets are not known

6. Contents Summary Spectrum sharing framework
Operational guidelines and calculations

7. No incumbents MFCN has exclusive access to spectrum
MFCN BS
No incumbents MFCN has exclusive access to spectrum
MFCN BS
68 dBm/5MHz
MFCN BS
MFCN BS
MFCN BS
68 dBm/5MHz
68 dBm/5MHz
68 dBm/5MHz
MFCN BS
MFCN BS
MFCN BS
68 dBm/5MHz
68 dBm/5MHz
68 dBm/5MHz
68 dBm/5MHz

8. FSS/FS incumbents Non-exclusive access to spectrum
MFCN BS
FSS/FS incumbents Non-exclusive access to spectrum
FSS
MFCN BS
MFCN BS
MFCN BS
MFCN BS FS
MFCN BS
MFCN BS
MFCN BS

9. Accounting for multiple base stations and sectors
Three possible approaches can be identified to account for interference from multiple MFCN base station sectors (i.e., for the aggregation effect):
Single-sector calculations with inclusion of a specific ‘safety’ margin to account for the actual existence of multiple sectors.
Single-operator (multi-sector) calculations with insectors clusion of a specific ‘safety’ margin to account for the actual existence of multiple from other operators.
Multi-operator (multi-sector) calculations with no* specific safety margin.
* National regulators may specify safety margins for reasons other than aggregation.

10. Option A: MFCN operators perform calculations
Calculations are performed independently by the MFCN operators, with regulatory oversight.
Regulator
MFCN operator 1
Calculations
Sharing-specific provisions attached to the frequency usage rights
Calculations
MFCN operator 2
Calculations
(optional/reference)
Calculations
MFCN operator 3
Database of
FSS receivers
MFCN operators’ calculations may be subject to
regulator oversight
Database of
FS receivers

11. Option B: Third party performs calculations
Calculations are performed by a third party on behalf of all MFCN operators, with regulatory oversight.
Regulator
MFCN operator 1
Sharing-specific provisions attached to the frequency usage rights
Third Party
MFCN operator 2
Calculations
Calculations
(optional/reference)
Third party’s calculations may be subject to regulator oversight
MFCN operator 3
Database of
FSS receivers
Database of
FS receivers

12. Option C: Regulator performs calculations
Calculations are performed by the national regulator.
Regulator
MFCN operator 1
Sharing-specific provisions attached to the frequency usage rights
MFCN operator 2
Calculations
MFCN operator 3
Database of
FSS receivers
Database of
FS receivers

13. Contents Summary Spectrum sharing framework
Operational guidelines and calculations

14. Example geometry IFSS,T G1 G2 IFS,T P P P  f1 Most susceptible
FSS receiver
f1
f2
FSS MS
Maximum
permitted received interference:
IFSS,T FS
Frequency G1
coupling gain
including antenna gains &
angular discriminations
MS network
coverage
Most susceptible
FS receiver G2
coupling gain
including antenna gains &
angular discriminations
MFCN base station
Maximum permitted received interference:
IFS,T P P
P 

15. Calculations gTx GProp gRxGA,Rx GP Regulator may specify Calculate:
calculation of coupling gain:
Propagation and antennas
Calculate:
Maximum permitted
EIRP
Regulator specifies
maximum permitted
interference P
gTx
Propagation gain
GProp
gRxGA,Rx GP Rx
MFCN
base station
FSS
Regulator may specify:
interferer’s leakage (ACLR)
and receiver selectivity (ACS)

16. Interference from multiple sources (aggregation)
Total interference must not exceed the maximum value permitted
Maximum permitted (target) interference, IT
0.5 dB
Sector #5, I5
Sector #4, I4
Aggregated
interference I
Sector #3, I3
Sector #2, I2
Sector #1, I1

17. Partitioning of interference budget
Operator distributes its allocated interference budget among sectors
Total interference budget equally partitioned to three operators
Maximum permitted (target) interference, IT
MFCN
operator #3
Aggregated
interference I
MFCN
operator #2
MFCN
operator #1

18. Simple restriction zones (to reduce complexity)
Simple and cautious restriction zones can be used to reduce computational complexity. Base stations outside the restriction zones would not be subject to any restrictions for the avoidance of harmful interference to the FSS/FS.
f = 0
FSS/FS
receiver) 24
dBm 68
f  0
receiver
Cautious restriction zones for OMNI BS

19. More precise restriction zones
Include:
more sophisticated propagation models
digital terrain maps, and
receiver angular discrimination 60
Macro cell 40
Outdoor small cell 20
Indoor small cell
-20
-40
dBm / x MHz