A methodology for establishing national frameworks for spectrum sharing between MFCNs and FSS/FS in the 3.6-3.8 GHz band 20 April 2015

Contents Summary Spectrum sharing framework Operational guidelines and calculations

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.

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.

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

Contents Summary Spectrum sharing framework Operational guidelines and calculations

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

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

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.

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

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

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

Contents Summary Spectrum sharing framework Operational guidelines and calculations

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 

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)

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

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

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

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