Updated Propagation Model for DPA Protection

Wireless Innovation Forum CBRS Committee, Working Group 1

Source: Masoud Olfat. (Masoud.olfat@federatedwireless.com) On behalf of Amdocs, CommScope, FW, Google, Nokia, RED Technologies, Sony

Date: 1/25/2023

Distribution: WG1

Document Summary: WINNF-TS-1020

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4.6 Clutter Loss and Activity Factor Loss for Federal Incumbent Protection

REL1Ext-R2-SGN-03: Apply the following text deletion (text strike) and addition (in square bracket) to R2-SGN-03 specified in WINNF-TS-0112-V1.9.1:

R2-SGN-03: For Initial Certification, SAS shall use the NTIA ITS Irregular Terrain Model (ITM)1 in point-to-point mode for propagation determination for use in FSS earth station, DPA protection, and ESC sensor protection. Consideration of propagation models, including hybrid or application-specific models, may advance beyond this initial model, subject to FCC approval. If the CBSD is indoors, add 15 dB to the computed loss to account for attenuation due to building loss. [For DPA protection, the median ITM propagation loss for each CBSD is increased by the following losses:

• a. For all CBSDs with Antenna Height Above Ground Level (AGL) less than or equal 6 meters, SAS shall apply median clutter loss by the equations obtained from Recommendation ITU-R P.21082 , section 3.2 (Terrestrial Terminal Within the Clutter) to the ITM propagation loss. The following equations are derived from ITU-0R P.2108, Section 2 equations, by seeting the following parameters:

f: Operational Frequency: Set to 3600, and the unit is MHz.
p: Percentage Location Range, set to 50, and the unit is %
d: Path Length from CBSD to the DPA protection point in km.
Lctt: The median clutter loss, to be calculated by Equation xx and is limited by Statements yy and zz.

$$L_{ctt}(dB) = 15\log(10^{-6.1024} + 10^{-6.9298 - 4.78d})$$

The clutter loss, Lctt shall be limited by the following statements:

$$L_{ctt} \le L_{ctt2km}$$

where Lcc-2km is the value of Lctt at d = 2 km, and

$$L_{ctt} = 0 \ dB \ \text{for} \ d < 0.25 \ km$$

Figure tt: Median Path loss at 3600 MHz

• b. For all CBSDs, SAS shall apply an additional 8 dB loss to account for Time Division Duplex (TDD) and Network Loading Factor.

Note: For practical implementation reasons, if the antenna height of a CBSD or a protected entity is lower than 1 meter above the ground level, the antenna height is taken to be 1 meter above the ground level in the ITM model for initial certification.

Note 2: The reference implementation is maintained in the WInnForum code repository.

REL1Ext-R2-SGN-12 Apply the following text deletion (text strike) and addition (in square bracket) to R2-SGN-12 specified in WINNF-TS-0112-V1.9.1:

R2-SGN-12: Aggregate Interference Calculations

• a. The aggregate interference calculations done by the SAS shall employ a method that results in no smaller aggregate interference than that calculated by a Monte Carlo method using 1000 sampling iterations. Each iteration uses interference realizations from a specified set of interfering CBSDs, determined by drawing a random contribution from the Cumulative Distribution Function (CDF) of the interference caused by that CBSD. [The interference value caused by each CBSD to any DPA point is modified as in REL1Ext-R2-SGN-03 (a) and REL1Ext-R2-SGN-03 (b)].
• b. For the ITM model, the CDF to be used for interference realizations shall be that given by fixing the confidence parameter at 0.5 and varying the reliability parameter. [The ITM value calculated for all CBSDs for the protection of any DPA point is increased as specified in REL1Ext-R2- SGN-03 (a) and REL1Ext-R2-SGN-03 (b)]. Note: this value can be calculated relative to a median value for a specific path by using the 'avar' method in the reference implementation.

4.7 DPA Neighborhood for Federal Incumbent Protection

REL1Ext-R2-SGN-24: Apply the following text deletion (text strike) and addition (in square bracket) to R2-SGN-124 specified in WINNF-TS-0112-V1.9.1:

R2-SGN-24: DPA Protection Procedure

a. In the case of co-channel frequency range protection for offshore or inland DPAs, for each protection point, p, under consideration within the given DPA and for any co-channel frequency range ch, designate the protection constraint c = <p,ch> and define Nc to be the total number of CBSDs having or requesting a co-channel grant that includes any portion of the frequency range ch, and that are within a neighborhood of protection point p.

For each protection constraint c, the SAS shall determine the Nc CBSDs that are considered to be within the neighborhood of protection constraint <p,ch> in a manner that is substantially similar4 to the following procedure:

• i. A Category A [Outdoor] CBSDi [with AGL <= 6m] shall be included in the neighborhood of protection constraint <p,ch> if and only if CBSDi is less than or equal to [R_C_Out_<=6m_DPAA km] from protection point p
• ii. A Category A Outdoor CBSDi with AGL > 6m shall be included in the neighborhood of protection constraint <p,ch> if and only if CBSDi is less than or equal to R_C_Out_>6m_DPAA km from protection point p.
• iii. A Category A Indoor CBSDi with AGL <= 6m shall be included in the neighborhood of protection constraint <p,ch> if and only if CBSDi is less than or equal to R_C_In_<=6m_DPAA km from protection point p.
• iv. A Category A Indoor CBSDi with AGL > 6m shall be included in the neighborhood of protection constraint <p,ch> if and only if CBSDi is less than or equal to R_C_In_>6m_DPAA km from protection point p. ]
• v. A Category B CBSDi [with AGL <= 6m] shall be included in the neighborhood of protection constraint <p,ch> if and only if CBSDi is less than or equal to [R_C_<=6m_DPAB km] from protection point p.
• vi. [A Category B CBSDi with AGL > 6m shall be included in the neighborhood of protection constraint <p,ch> if and only if CBSDi is less than or equal to R_C_>6m_DPAB km from protection point *p.]*

The values of R_C_DPAA and R_C_DPAB [ R_C_Out_<=6m_DPAA , R_C_Out_>6m_DPAA , R_C_In_<=6m_DPAA , R_C_In_<=6m_DPAA , R_C_<=6m_DPAB , and R_C_>6m_DPAB] for co-channel in-land and offshore DPAs are captured in DPA KML files determined in [Ref-14].

b. In the case of out-of-band frequency range protection for inland DPAs, for each protection point, p, under consideration within the given DPA and for any protected out-of-band frequency range, ch, designate the protection constraint c = <p,ch> and define Nc to be the total number of CBSDs having or requesting any grant, and that are within a neighborhood of protection point p.

For each protection constraint c, the SAS shall determine the Nc CBSDs that are considered to be within the neighborhood of protection constraint <p,ch> in a manner that is substantially similar5 to the following procedure:

• i. A Category A CBSDii shall be included in the neighborhood of protection constraint <p,ch> if and only if CBSDi is less than or equal to R_O_DPAA km from protection point p.
• ii. A Category B CBSDi shall be included in the neighborhood of protection constraint <p,ch> if and only if CBSDi is less than or equal to R_O_DPAB km from protection point p.

The values of R_O_DPAA and R_O_DPAB for co-channel in-land and offshore DPAs are captured in DPA KML files determined in [Ref-14].

• c. For every protection constraint, c (i.e., for each of the protection constraints <p,ch> corresponding to every protection point p under consideration within a given protection area DPA and for every applicable frequency range ch), the SAS shall determine the associated DPA Move List Mc (see [R2-SGN-24 (d)]) using a method that generates results that are substantially similar to the following procedures:
  • i. Form the ordered list Sc,sorted = [CBSD1, CBSD2, … CBSDNc], sorted according to increasing values of (PCBSD,ch + GCBSDi->c - LCBSDi,c), where PCBSD,ch is the CBSD conducted power (in dBm) on frequency range ch, GCBSDi->c is the CBSD antenna gain in the direction of the protection point p (in dBi) [R2-SGN-20], and LCBSDi,c is the median path loss based on ITM model as defined in [R2-SGN-03 REL1Ext-R2-SGN-03] from CBSDi to the protection point p (in dB).
  • ii. In case of out of band frequency range protection of inland DPAs,
    • For CBSDs having multiple grants, the grant closest to "ch" is taken into account.
    • The CBSD conducted power PCBSD,ch, is replaced with one of the three values, -13 dBm/MHz, -25 dBm/MHz*,* or -40 dBm/MHz*,* depending on the distance of closest edge of the grant operational frequency range to "ch", as defined in R0-DEV-05(e)
    • If the out of band inland DPA is operating below 3550 MHz and is always activated, ch is assumed to be the frequency range 3540-3550 MHz.
  • iii. DPA Move List analysis is performed using increments of half of beamwidth (beamwidth/2), where beamwidth is defined in the appropriate KML file in [Ref-14], over the azimuth range of the given DPA, where the azimuth range is defined in the appropriate KML file in [Ref-14].
  • iv. Find the largest nc, 1<=nc<=Nc, such that CDFc,a(nc) does not violate 95% threshold for all potential azimuths, a, where CDFc,a(nc) is the CDF of sum of the interference from the fundamental emission (in case of co-channel DPA protection) or the out-of-band emission (in case of out-of-band inland DPA protection) of the first nc elements of Sc,sorted (i.e., CBSD1, CBSD2, …, CBSDnc) given radar gain Gr,c->a (per [R2-IPM-04]) for a federal incumbent radar r, hypothetically located at the protection point p associated with constraint c, in the direction of azimuth a.
  • v. The associated DPA Move List, Mc, corresponding to protection constraints c is determined to be {CBSDnc+1, CBSDnc+2, …, CBSDNc}.

Note: e.g., if the upper edge of ch falls at or below 3530 MHz, the value of -40 dBm/MHz, and if ch falls at or below 3540 MHz but above 3530 MHz, the value of -25 dBm/MHz is assumed for all grants.

See NTIA – ITS Irregular Terrain Model (ITM) (Longley-Rice) ( 20MHz-20 GHz)