Decision on SRSP-520, issue 3 and RSS-192, issue 5

Through the release of this document, Innovation, Science and Economic Development Canada (ISED), on behalf of the Minister of Innovation, Science and Industry (the Minister), announces the decisions resulting from the technical consultation on Standard Radio System Plan SRSP-520, issue 3, Technical Requirements for Fixed and/or Mobile Systems, Including Flexible Use Broadband Systems, in the Band 3450-3900 MHz (the SRSP) and Radio Standards Specification RSS-192, issue 5, Flexible Use Broadband Equipment Operating in the Band 3450-3900 MHz (the RSS).

In spring 2020, ISED published two technical standards, SRSP-520, issue 1, Technical Requirements for Fixed and/or Mobile Systems, Including Flexible Use Broadband Systems, in the Band 3450-3650 MHz, and RSS-192, issue 4, Flexible Use Broadband Equipment Operating in the Band 3450-3650 MHz, based on SLPB-001-20, Policy and Licensing Framework for Spectrum in the 3500 MHz Band. These standards were published in preparation for the 3500 MHz spectrum auction, which was held in June 2021. The standards provide coexistence and coordination requirements between flexible use operations and other in-band and adjacent-band services and certification requirements for 3500 MHz flexible use equipment.

In May 2021, ISED published SLPB-002-21, Decision on the Technical and Policy Framework for the 3650-4200 MHz Band and Changes to the Frequency Allocation of the 3500-3650 MHz Band (the 3800 MHz Policy Decision). This 3800 MHz Policy Decision sets rules around the treatment of incumbents, including wireless broadband services (WBS), fixed services (FS) and fixed satellite services (FSS).

Following the publication of the 3500 MHz technical rules and the 3800 MHz Policy Decision, spectrum and aviation regulators around the world, including ISED, became aware of studies that showed the possibility of interference to radio altimeters (which are crucial safety-of-life aviation sensors) operating in the 4200-4400 MHz band from signals outside their band of operation, which could include signals from flexible use 5G systems in both the 3450-3650 MHz (3500 MHz) and 3650-3900 MHz (3800 MHz) bands.

In order to protect radio altimeters, on November 18, 2021, ISED published the Decision on Amendments to SRSP-520, Technical Requirement for Fixed and/or Mobile Systems, Including Flexible Use Broadband Systems, in the Band 3450-3650 MHz, which included mitigation measures to protect radio altimeter operations from potential harmful interference from flexible use systems in the 3500 MHz band, as set forth in issue 2 of SRSP-520.

The main protection measures included:

• exclusion and protection zones to mitigate interference to aircraft around certain airport runways where automated landing is authorized
• a national antenna down-tilt requirement to protect aircraft used in low altitude military operations, search and rescue operations and medical evacuations throughout the country

On December 23, 2021, Transport Canada released a Civil Aviation Safety Alert to raise awareness of the potential risk of 5G interference and to recommend precautionary operational measures prior to fully understanding the impact of 5G systems on radio altimeters. Transport Canada’s recommendations included advising operators to identify all possible indications that might be evidence of possible radio altimeter disturbance in their aircraft and ensure that this information is provided to flight crews, to perform risk assessments and if required, to implement procedures and operational restrictions.

In June 2022, ISED published SPB-002-22, Policy and Licensing Framework for Spectrum in the 3800 MHz Band (the 3800 MHz Licensing Framework Decision), which extended the mitigation measures for the 3500 MHz band to the 3650-3900 MHz band while international and domestic studies were still underway to further assess the potential adjacent-band interference to radio altimeters from flexible use operations. The aforementioned document also provided the timeframe of October 2023 for the start of the 3800 MHz spectrum auction.

On December 19, 2022, ISED initiated the Consultation on SRSP-520, issue 3 and RSS-192, issue 5 (the Consultation) based on studies completed by ISED on the coexistence between radio altimeters and 5G operations, as well as on requirements stemming from the policy decisions in the 3800 MHz Policy Decision and the 3800 MHz Licensing Framework Decision.

Comments and reply comments on the Consultation were received from:

• Bell Mobility (Bell)
• Canadian Airports Council (CAC)
• Canadian Association of Wireless Internet Service Providers (CanWISP)
• Canadian Electronics & Communications Association (CECA)
• Coalition of Aviation and Aerospace Stakeholders - members are Airborne Public Safety Association, Airlines for America, Air Line Pilots Association Canada, AIRBUS Operations, S.A.S., Air Transport Association of Canada, Canadian Business Aviation Association, Garmin International, Inc., International Air Transportation Association, Helicopter Association of Canada, National Airlines Council of Canada, National Business Aviation Association, NAV CANADA, Raytheon Technologies, Textron Aviation, Thales Group and The Boeing Company (the Coalition)
• De Havilland Aircraft of Canada Limited (DHC)
• Department of National Defence (DND)
• Global Satellite Operators Association (GSOA)
• Government of Northwest Territories
• Kelowna International Airport
• Mobile Interest Group (MIG) - members are Bell, Rogers, SaskTel, TELUS, Ericsson, Nokia and Samsung
• National Airlines Council of Canada (NACC)
• People’s Republic of China
• Radio Advisory Board of Canada (RABC)
• Rogers Communications Inc. (Rogers)
• SaskTel
• Telesat
• TELUS
• Transport Canada (TC)

ISED sought comments on the proposed exclusion and protection zones to protect category 1 aircraft landing at the 26 airports and 43 runways where automated landing is authorized, as identified in ISED’s Map of Exclusion Zones and Protection Zones (SRSP-520).

Summary of comments on exclusion and protection zones around airports

Comments were provided by Bell, CAC, the Coalition, DHC, the Government of the Northwest Territories, Kelowna International Airport, MIG, NACC, RABC, Rogers, Sasktel, TC and TELUS.

The Coalition requested that Radio Technical Commission for Aeronautics (RTCA) user category 1 and category 2 radio altimeters be protected. The Coalition recommended that ISED work with TC and the airline industry to identify a list of en route alternate airports and critical small hubs for air service and to also define exclusion and protection zones that are based on all aspects of real-world operational flight volumes (Obstacle Clearance Surface (OCS), additional safety margins, etc.).

DHC noted the Group 4 power spectral density levels (Group 4 curve) proposed by the Federal Aviation Administration (FAA) and stressed the importance of harmonization between Canada and the United States (US). DHC further suggested that Canada should ensure the power spectral density levels arriving at the receiver port of the aircraft radio altimeter antenna in the 3700-3980 MHz band does not exceed the Group 4 curve. DHC indicated that this would require Canada to reverse engineer the 5G environment starting with the Group 4 levels at the aircraft radio altimeter antenna receiver port and working back to define the 5G environment at the base station, including the definition of the runway safety zone, assumptions concerning the proximity and orientation of aircraft with 5G base stations, and the base station data (tower height, power levels, elevation mask, etc.).

Kelowna International Airport requested to be added as a protected airport since the airport has a category 1 instrument landing systems (ILS) approach and several Required Navigation Performance (RNP) and circling approaches.

The Government of the Northwest Territories indicated that in addition to Yellowknife Airport (CYZF), which currently has exclusion and protection zones, two other airports with the ILS approach in the territory, Hay River (CYHY) and Inuvik (CYEV) airports, should also be protected. It also recommended that ISED protect alternate airports (Norman Wells (CYVQ), Fort Simpson (CYFS), Fort Smith (CYSM) etc.) from potential interference.

TC proposed that ISED adopt exclusion and protection zones for 34 airports in Canada instead of the current 26 airports. TC noted that the 8 additional airports are essential to guarantee Extended Range Twin-Engine Operations (ETOPS) service in case an aircraft engine becomes inoperable. TC also requested that exclusion and protection zones for the 3500 MHz and 3800 MHz bands be based on the international OCS, with tower separation requirements calculated using TC’s proposed power spectral density curves and taking into account appropriate spurious emissions limit.

NACC identified 87 airports and requested that all of their runways be protected, while CAC requested that all commercial airports be included on the protected list, including all runways with instrument approaches such as RNP and other technology.

Bell requested that ISED remove all mitigation measures for the 26 airports for the 3500 MHz band and keep an antenna down-tilt requirement and the 77.5 dBm per carrier equivalent isotropically radiated power (e.i.r.p.) limit in the protection zones for the 3500 MHz band. Bell, with support from Rogers and TELUS, also suggested that ISED remove Altimeter Under Test.08 (AUT.08) in table A.1 of the Consultation from its assessment as it displayed worse behavior in the 3500 MHz band than in the 3800 MHz band. Bell further indicated that it had issues with extra margins in ISED’s loop loss values and that ISED did not consider fault tolerance in its assessment. Finally, Bell proposed that a maximum e.i.r.p. of 77.5 dBm per carrier should not be applied outside of the protection zones. In its reply comments, Bell recommended that TC’s proposal be modified to account for the FAA Group 4 curve for the 3800 MHz zones around airports to align with the US. Further, Bell mentioned that aligning to the Group 4 curve would make the measures in the 3500 MHz band irrelevant.

MIG requested that ISED remove all requirements below 3700 MHz and that the e.i.r.p limit should only apply to protection zones. MIG supported increasing the e.i.r.p. limit to 80.5 dBm per carrier due to the single polarization supported by radio altimeters.

Rogers recommended that ISED remove all mitigation measures for the 26 airports in the 3450-3800 MHz band.

Sasktel objected to the establishment of zones, but acknowledged that they will exist around airports in the short term. However, it requested that ISED resolve this issue by requiring aviation stakeholders to update their radio altimeters in a reasonable timeframe.

TELUS did not oppose exclusion and protection zones around the 26 airports, nor the additional 8 airports identified in TC’s submission, but noted that the e.i.r.p. limit of 77.5 dBm per carrier should only apply to protection zones. If new airports are added, TELUS, with support from Rogers, suggested that ISED should add those prior to the publication of SRSP-520, issue 3, and that the standard be frozen until the proposed sunset date. In its reply comments, TELUS noted that TC’s protection zones based on power limitation as a function of height appeared more operationally straightforward than ISED’s skyward and exclusion zone boundary power flux density limits outlined in the Consultation. However, it highlighted that TC’s approach should be a substitute and not an additive to ISED’s proposal. It further noted that if TC’s approach were to be adopted, the e.i.r.p. limit per carrier would not be needed.

Finally, the RABC recommended that the aviation industry seek clarification on approaches and surfaces from TC and on safety margins from ISED. It indicated that the telecom industry suggested that the maximum e.i.r.p. limit should increase from 77.5 dBm per carrier to 80.5 dBm per carrier and that the 77.5 dBm per carrier limit should apply only in exclusion and protection zones as opposed to on a national basis.

Discussion

ISED notes that various countries have adopted measures to protect the operation of radio altimeters onboard aircraft. For instance, France established security and precautionary zones (available only in French) for 17 airports to protect RTCA category 1 radio altimeter operations where low visibility landings are permitted. Brazil defined zones of 2100 metres beyond the edge of the runway and 910 metres on either side of runways for 95 airports to protect landings in low visibility conditions, similar to security and exclusion zones implemented in France and in ISED’s SRSP-520, issue 2. Australia proposed exclusion and protection zones around 21 airports, to protect 4 airports with ILS and 17 airports with a Required Navigation Performance with Authorization Required approach. Australia also based their zones on those from France and ISED. Finally, the US identified 188 airports, representing 92% of all passenger traffic, that required protection for low visibility approaches from 5G operations. The FAA decided to protect aircraft using runway safety zones developed using OCS for each airport. OCS can be used to model a protection zone by incorporating lateral and vertical variation of aircraft approaching a runway.

As per SRSP-520, issue 2, ISED currently protects 26 airports with protection and exclusion zones that were defined using France’s approach. These measures are based on the protection of category 2 and category 3 ILS landings, which ensures that aircraft can land in low visibility conditions with Autoland at those airports. In the Consultation released in December 2022, these zones were refined based on the results of ISED’s studies. Since the publication of the Consultation, research and further discussions with aviation and spectrum regulators have revealed other approaches and requirements to protect radio altimeters, which could be adopted for the 3500 MHz and 3800 MHz bands in Canada.

For instance, as part of its submission to this consultation process, TC recommended that 8 additional airports be protected to account for ETOPS. These 8 new airports are required as part of domestic and international safety requirements, and are used to ensure that aircraft can safely land when mechanical issues develop. Moreover, after the closing of the reply comments, TC recommended Kelowna be included in the list of protected airports based on passenger volume and geographical challenges (e.g. mountainous terrain). Considering the importance of ensuring domestic and international aviation safety requirements are met, ISED will expand the measures to the 9 new airports requested by TC (Comox, Kelowna and Victoria British Columbia; Whitehorse, Northwest Territories; North Bay, Ontario; Sydney, Nova Scotia; Deer Lake, Happy Valley-Goose Bay and Stephenville, Newfoundland and Labrador) in addition to the 26 airports currently in ISED’s Map of Exclusion Zones and Protection Zones (SRSP-520). The 35 protected airports represent approximately 93% of passenger traffic in Canada, which is similar to the passenger coverage of the protected airports in the US.

TC and some aviation stakeholders also noted that present ILS zones do not account for aircraft operational volume. They noted that OCS accounts for vertical and lateral variabilities on aircraft approach that are not reflected in the currently adopted ILS zones. As such, they suggested that ISED adopt zones based on OCS similar to the FAA. Given the importance of accounting for operational volumes and the different aircraft approaches, ISED will adjust the protection and exclusion zones based on OCS for both the 3500 MHz and 3800 MHz bands. Further, these protection measures will be based on TC’s proposed e.i.r.p. spectral density curves, which will enable TC to identify airplanes with 5G tolerant radio altimeters that can operate safely at protected airports. With the introduction of these new OCS zones, the maximum e.i.r.p. of 77.5 dBm per carrier will be replaced with restrictions based on e.i.r.p. and tower height. However, the equation associated with the maximum permissible e.i.r.p. in paragraph 34 of the proposed SRSP (see annex B of the Consultation) will be removed to enable coexistence between existing and future base stations in the 3500 MHz and 3800 MHz bands and radio altimeters by ensuring e.i.r.p. does not exceed 61 dBm/MHz.

A key benefit of adjusting the protection and exclusion zones using OCS and TC’s e.i.r.p. spectrum density curves is the close harmonization with the FAA requirements, which will facilitate cross border air traffic between Canada and the US, while enabling deployment of 5G operations across Canada.

Finally, some stakeholders recommended the removal of mitigation measures below 3700 MHz and 3800 MHz. Based on ISED’s results described in annex A of the Consultation, 5G operations between 3450-3800 MHz can potentially impact certain radio altimeters. As such, the mitigation measures on 5G operations in this frequency range will remain for now.

Decision

ISED sought comments on the proposal to maintain the antenna down-tilt requirement outside of large population centres (LPCs) to protect low-altitude military operations, search and rescue operations and medical evacuations. ISED also sought comments on whether medium population centres (MPCs) should also be excluded from the antenna down-tilt requirement.

Summary of comments on antenna down-tilt requirement

Comments on the proposal to maintain the antenna down-tilt requirements outside of LPCs to protect low-altitude military operations, search and rescue operations and medical evacuations were provided by Bell, the Coalition, MIG, RABC, Rogers, Sasktel, TC and TELUS.

The Coalition recommended that ISED retain the national antenna down-tilt requirement. The RABC also indicated that the aviation industry in general recommended that the antenna down-tilt requirements be maintained nationally.

DND supported the removal of the antenna down-tilt requirement in LPCs only. It stated that the antenna down-tilt requirement outside LPCs was required to protect low-altitude military operations, search and rescue operations and medical evacuations, and that these operations can occur anywhere in the country, especially outside LPCs.

Bell, MIG, RABC, Rogers, Sasktel and TELUS supported the removal of the antenna down-tilt restriction in LPCs and MPCs. Bell stated that its internal analysis confirmed ISED’s results and demonstrated that shadowing and clutter losses in LPCs and MPCs will mitigate potential interference to helicopter operations. MIG stated that military, search and rescue and medical evacuations are unlikely in LPCs and MPCs, while Rogers noted that there is no evidence that military and search and rescue operations would occur in MPCs. Moreover, MIG and Rogers both noted that antenna uptilt is required to serve high-rise buildings. Sasktel added that antenna uptilt can be used to serve customers in hilly terrain, while TELUS noted that antenna uptilt can be used to optimize network coverage in some instances. Finally, Rogers recommended that a 3-degree antenna uptilt limit be adopted in non-built-up areas in Canada.

TC recommended that ISED maintain measures to limit skyward emissions to avoid an unpredictable operating environment for pilots. It recommended that ISED adopt a national e.i.r.p. elevation mask, similar to the approach taken by the FAA. It also recommended a C-band mitigation e.i.r.p. elevation mask near airports to minimize skyward emissions.

Bell and TELUS, in their reply comments, supported TC’s proposal for a national e.i.r.p. mask. Bell also believed that ISED should allow for unmitigated antenna up-tilt in LPCs, as proposed in the Consultation.

Discussion

ISED has reviewed all comments and considered the most balanced approach for both telecommunications and aviation industries to protect radio altimeters, while reducing impact on 5G deployments in Canada. ISED is of the view that a national e.i.r.p. mask and an airport e.i.r.p. mask around protected airports similar to that of the FAA and proposed by TC, will strike the right balance. As such, the SRSP will include a national e.i.r.p. mask where it will provide a limited antenna uptilt based on combined mechanical and digital tilt of 7 degrees from the horizon at maximum power, with decreasing power levels as antenna uptilt angles increase. Moreover, the SRSP will include an airport e.i.r.p. mask that will apply within protection zones defined around the 35 protected airports based on a combined mechanical and digital tilt of 0 degrees from the horizon at maximum power, with decreasing power levels as antenna uptilt angles increase for both 3500 MHz and 3800 MHz base stations. Once the exclusion zones are lifted after January 1, 2026, this airport e.i.r.p. mask will only apply to 3800 MHz base stations in those exclusion and protection areas until December 31, 2027.

Existing base stations in Canada are predominantly designed to transmit radio waves from a higher elevation to a lower elevation (e.g. from the top of a building or tower towards the ground). The height and tilt of a base station antenna is selected to ensure coverage and capacity requirements are met in the targeted area. Only a small percentage of existing base stations is used to serve multi-dwellings (MDUs) or mountainous areas from a lower elevation to a higher elevation, requiring pointing above the horizon (i.e. an uptilt angle). Consequently, ISED is of the view that imposing a national e.i.r.p. mask will have minimal impact on 5G deployments in Canada while providing protection to radio altimeters by minimizing skyward emissions from 5G base stations.

Decision

ISED sought comments on the proposed exclusion and protection zones around 58 H1 classified heliports, as listed in annex D of the Consultation document, to protect helicopters. Moreover, ISED sought comments on whether the same protection zone sizes should be applied across Canada or whether different sizes should be applied at each heliport, despite potential operational complexity for 5G operators.

Summary of comments on exclusion and protection zones around 58 H1 heliports, including size of the protection zones

CECA, the Coalition, MIG and the RABC supported the exclusion and protection zones around H1 classified heliports. The Coalition supported an exclusion zone of 80 metres in radius centered at the heliport final approach and take-off (FATO) area, and recommended protection of all approach surfaces out to 1050 metres to cover the entire approach and all critical phases of approach.

In its initial comments, TELUS did not object to introducing temporary exclusion and protection zones around heliports, but noted the approach is arguably more impactful for heliports than it is for airports given the large number of Class H1 heliports located in major urban centers. Further, TELUS requested detailed information on the heliports’ latitudes, longitudes and elevations, or the publication of maps as part of the publication of the SRSP. TELUS strongly recommended that the list of H1 heliports be frozen at time of publication of the SRSP in order to create a predictable environment for network planning. Finally, TELUS, with support from Rogers, requested that ISED extend the analysis and submission of attestations indicating compliance with any new or modified pfd limits from 15 days to 60 days in the SRSP as a more reasonable timeframe.

Bell, Rogers and SaskTel did not support exclusion and protection zones around H1 classified heliports. Rogers was of the view that exclusion zones should be enhanced protection zones rather than strict exclusion zones. Furthermore, Rogers believed that protection zones of 500 metres in radius and greater to be excessive and unnecessary.

As for the size of the protection zones, CECA, the Coalition, MIG, RABC and TELUS supported different protection zone sizes based on the heliport parameters and surrounding environment. While Bell, Rogers and SaskTel did not support the exclusion and protection zones around heliports, it was noted that if introduced, the size of the protection zones should be customized for each heliport based on the environment.

Bell, MIG and Rogers suggested that ISED and TC follow the FAA example through clear guidelines with respect to helicopter operations and by imposing mitigation measures on the aviation industry, rather than on 5G operations.

As a balanced approach to impose mitigations measures on both the aviation and the telecommunication industries, TC recommended aligning with the US on the heliports, which would see the exclusion and protection zones being removed around heliports. Bell, Rogers and TELUS supported TC’s proposal in their reply comments. TC would issue operational limitations, advisory Notice to Airmen (NOTAMs), and guidance to the Pilots in Command (PIC), including other measures such as supplementary training. However, they requested a Canadian approach to limit spurious emissions that enables TC to conclude it meets a comparable level of safety and security for the aviation industry, as achieved namely in the US TC further recommended a national e.i.r.p. elevation mask to minimize skyward emissions.

Discussion

As mentioned in the Consultation document, some countries have imposed mitigation measures on 5G operations to protect helicopters while others have instead imposed restrictions on aviation operations. For instance, France has implemented a safety zone of 1 km around 10 heliports. In Japan, 5G base stations should be kept at a physical distance of at least 50 metres for a micro-cell station and at least 20 metres for a small-cell station. In the US, the FAA has imposed restrictions on the aviation industry via advisory NOTAMs. Operators must comply with specific conditions and limitations. In April 2023, the FAA released a Notice of proposed rulemaking (NPRM) on helicopters, where prohibitions on operations would continue to apply unless susceptible radio altimeters are upgraded by July 1, 2023.

In the Consultation, ISED proposed exclusion zones of 80 metres and protection zones between 500 and 1000 metres around 58 heliports across Canada. Taking into account all comments received, ISED will not include these zones in SRSP-520, issue 3, in order to achieve a balanced approach on mitigation measures required by both the telecommunications and aviation industries.

ISED expects that TC, as per its submission, will issue operational limitations and NOTAMs on helicopter operations, and provide guidance to the PIC, including other appropriate measures deemed necessary.

As mentioned in the previous discussion, ISED will impose a national e.i.r.p. mask to reduce skyward emissions from 5G base stations, which will provide a predictable radio frequency environment for low altitude military operations, search and rescue operations and medical evacuation, while minimizing the impact on 5G operations.

Decision

ISED sought comments on whether additional mitigation measures should be imposed on 5G operations in the 3500 MHz and 3800 MHz bands.

Summary of comments on additional mitigation measures

Bell, MIG, Rogers, SaskTel and TELUS recommended that no additional mitigation measures be imposed on 5G operations in the 3500 MHz and 3800 MHz bands. Bell proposed that retrofits of aviation equipment (including helicopters) be imposed. Rogers added that if any additional temporary coexistence measures were to be considered, they should be solely borne by the aviation industry. Rogers is of the view that the current coexistence challenge between services that have 300-550 MHz of spectral separation is the result of the aviation industry’s deficient equipment. SaskTel submitted that there should be mandated installation of frequency filters for altimeters or replacement of defective aviation equipment in Canadian aircraft. TELUS noted that the proposed measures in the Consultation to address coexistence concerns would fall entirely on the telecommunication industry in the short term. TELUS suggested that no additional mitigation measures should be imposed on the telecommunication industry since the issue of radio altimeter vulnerability to the fundamental emissions of 5G systems can be resolved by the aviation industry through updating its equipment to be resilient to adjacent-band interference – a responsibility that must be enforced in a timely manner.

TC recommended that ISED, in consultation with TC, could authorize alternative agreements with individual 5G licensees and aircraft operators that would permit some differences in the means and extent to which licences and operators are to comply with the requirements stated, while maintaining a comparable level of aviation safety. Further, in its reply comments, TC highlighted the importance of coordinating with telecommunication stakeholders to provide a two-month advanced notice of the start of 5G C-band operations to facilitate TC’s planning of aviation restrictions and associated alleviations.

Bell recommended that ISED adopt a flexible approach similar to that of the US, such that deviation from the SRSP is allowed in both exclusion and protection zones, subject to regulatory approval.

Discussion

ISED has carefully reviewed all comments received. With regards to comments on a balanced approach, with mitigation measures imposed on both the telecommunication and aviation industries, ISED is of the view that the mitigation measures being adopted strike the right balance between both industries. ISED will look to TC, as the Canadian aviation regulator responsible for air safety, to release specific mitigation measures on aviation such as NOTAMs, retrofit requirements, guidance to PIC and other notices deemed necessary.

Based on TC and Bell’s recommendation on alternative agreements, ISED notes that typical language can be found in other SRSP documents, where affected parties can deviate from coordination requirements described in these standards when mutually agreed upon by these affected parties. In this case, ISED will allow alternative agreements between telecommunication and aviation industries. These agreements will need to be submitted to both ISED and TC for approval prior to implementing the alternative measures.

With regards to advanced notice from the telecommunication industry, ISED requires 3500 MHz and 3800 MHz licensees to provide pre-operation reports 15 days prior to the operation of base stations in protection zones around protected airports. ISED will extend that requirement to include the submission of these reports directly to TC to facilitate their planning process. Furthermore, there is an ongoing ISED consultation on site-upload requirements, including the requirement that terrestrial licensees upload current and accurate data information for all stations on a monthly basis in ISED’s Spectrum Management System (SMS) database as part of their conditions of licence. ISED strongly recommends that licensees upload their site data for the 3500 MHz and 3800 MHz bands in a timely manner (i.e., shortly before stations are live) rather than on a monthly basis. This information will allow stakeholders such as TC to make timely and appropriate plans. Licensees must ensure that their stations are in compliance with the applicable technical and operational requirements at all times. Failure to do so can result in ISED taking enforceable measures, including requiring licensees to cease operation of the station(s), licence revocation, and/or imposing Administrative Monetary Penalties.

If TC requires additional notifications and data beyond what is described above, they are encouraged to discuss directly with 3500 MHz and 3800 MHz licensees to obtain the information, similar to the voluntary arrangements made between the FAA and mobile operators in the US. ISED encourages licensees to collaborate with TC in providing the necessary information to facilitate TC’s planning of aviation restrictions and alleviations accordingly.

Decision

ISED also received comments on the sunset date of March 31, 2025 to remove the mitigation measures on 5G operation.

Summary of comments on sunset date

Bell, MIG and SaskTel proposed that the sunset date be changed from March 2025 to February 2024 to align with the US timelines. Sasktel suggested that ISED and TC collaborate to set a final date for resolution of the radio altimeter issue through installation of frequency filters or outright replacement of malfunctioning altimeters. Sasktel added that the FAA is ending its accommodation for the aviation industry in early 2024. In addition, the MIG suggested that ISED enforce a sunset date for all radio altimeter related mitigation measures that is more aligned with the US and ensure compliance by the aviation industry by that date.

TELUS recommended that the proposed mitigation measures be terminated by March 31, 2025, as proposed by ISED.

Rogers recommended that ISED implement time limited mitigation measures in the 3800 3900 MHz band and that these measures be removed by March 31, 2025. Rogers did not support any extension to this deadline.

TC proposed that owners or operators retrofit their aircraft to Group 4 by January 1, 2026. As such, TC requested that existing ISED mitigation measures remain in place until the end of the retrofit date. In its comments, TC highlighted that after the US retrofit to Group 4 is completed, a C-band e.i.r.p mask would remain around certain airports until January 1, 2028 following a reassessment in July 2027. In its reply comments, TC further noted that the US announced that its voluntary measures are subject to a reassessment in July 2026, and will be kept until at least 2028, depending on the status of the aviation industry’s long-term migration to next-generation radio altimeters. TC requested that ISED consider a similar approach in Canada.

In its reply comments, Bell requested a sunset date of February 1, 2024 for the 3500 MHz band. Further, Bell recommended that ISED align the sunset date for all mitigation measures to be lifted on 3800 MHz with the US date of January 1, 2028.

TELUS, in its reply comments, highlighted that if Canada were to fully align with the US’s technical rules, the US timelines for voluntary commitments must be adopted. This commitment includes TC mandating Group 4 retrofit by February 1, 2024, a reassessment of the mitigation measures after the retrofit, a mid-term check-in in July 2026, and full sunset of all mitigation measures by January 1, 2028. TELUS also questioned the need for mitigation measures on the 3500 MHz band once the radio altimeters are upgraded.

In its reply comments, Rogers disagreed with TC’s request to extend mitigation measures until all aviation retrofits are completed. ISED should not further extend the Canadian sunset date beyond March 31, 2025.

The Coalition requested that ISED remove the specific sunset date. It further requested that if a sunset date is provided, it should be 7 years after the technical standard order (TSO) for new minimum operational performance standard (MOPS) compliant radio altimeters is released and issued for a full retrofit of aircraft. Another option proposed by the Coalition is to retrofit radio altimeters to interim group 4 performance found in the FAA’s NPRM, without removing all mitigation measures on the telecommunication industry. The Coalition, in its reply comments, highlighted concerns in meeting the January 1, 2026 date from TC’s submission during the comment period due to supply chain and logistic issues, and instead recommended that the relaxation of 5G limits be determined by the progress achieved by the aviation industry for retrofits.

Discussion

As mentioned previously, certain countries such as Australia, Brazil, France, Japan and the US, have imposed or are consulting on imposing mitigation measures on 5G operations to protect aviation operations. Some of these countries have already set time limiting mitigation measures on 5G operations so that radio altimeters are retrofitted or replaced with robust solutions.

In the US, the FAA released a rulemaking process in January 2023 and a final decision in May 2023 requiring aircraft operators to retrofit or upgrade their radio altimeters to Group 4 by February 1, 2024. Based on the voluntary agreement with the 4 largest US mobile operators, a few mitigation measures may remain until January 1, 2028, with a reassessment of the agreement based on the aviation industry’s progress towards next-generation radio altimeters. In Australia, the Australian Communications and Media Authority is imposing interim mitigation measures on 5G operations between 3700 MHz and 4000 MHz until March 31, 2026.

ISED has carefully reviewed all comments received. Most telecommunication stakeholders either supported the March 31, 2025 sunset date or requested an earlier date to align with the FAA retrofit date, while the aviation stakeholders requested the mitigation measures on 5G to remain much longer, up to an additional 7 years after the TSO standard is published. With the TSO standard yet to be published, this could represent a date of 2030 or later. TC requested a slight extension of 9 months, until January 1, 2026 as Canadian aircraft operators would have retrofitted applicable radio altimeters to the FAA Group 4 curve by this date.

In order to strike the right balance between providing sufficient time for aircraft operators to retrofit and minimizing impact on 5G deployments in Canada, ISED will extend the sunset date by 9 months, to January 1, 2026. On this date, the national e.i.r.p. mask, exclusion zones and the height and power restrictions within the protection zones for 3500 MHz and 3800 MHz bands will be removed.

ISED conducted additional simulations using the FAA Group 4 curve to model interference in a three-dimensional space utilizing the same assumptions described in tables A8 and A9 of annex A of the Consultation. In these simulations, ISED adjusted the FAA Group 4 curve to account for the fact that 3800 MHz higher power commercial mobile services stop at 3900 MHz in Canada, as opposed to 3980 MHz in the United States. The results showed significantly improved coexistence between 5G base stations and FAA Group 4 radio altimeters. The adjusted FAA Group 4 curve was respected when the aircraft and base station were as close as 5 metres (16.4 feet) vertically and 14 metres (45.9 feet) horizontally. While it is theoretically possible that the FAA Group 4 interference tolerance mask (ITM) could be exceeded for cases of unmitigated antenna uptilt by 3800 MHz base stations, the results of ISED’s simulations found that these would only occur in cases of extreme antenna uptilt (e.g. combined mechanical and digital tilt greater than 25 degrees). For example, at 25 degrees antenna uptilt, the adjusted FAA Group 4 curve was respected when the aircraft and base station were as close as 11 metres (36 feet) vertically and 21 metres (69 feet) horizontally. Aircraft operating with radio altimeters that respect the FAA Group 4 curve would not be susceptible to the emissions of 3500 MHz base stations in Canada.

As aforementioned, only a small percentage of existing base stations is used to serve tall MDUs or mountainous areas from a lower elevation to a higher elevation, requiring above the horizon antenna uptilt angle. Evaluation of data in ISED’s spectrum management database showed that higher angles of uptilt (e.g. more than 25 degrees) are only used to serve MDUs. As described in the Consultation, ISED’s computational analysis determined that 5G emissions will be shadowed when pointing towards tall buildings. In addition, these uptilted antennas in ISED’s database are not located near airport runways.

Further, elevated MDUs are typically not authorized along airport runway paths to provide proper clearance for landing and take-off of aircraft. As such, an antenna uptilt would be even less expected in areas around airports. Nevertheless, ISED will maintain an airport e.i.r.p. mask in the area covered by the former 3800 MHz exclusion zones and in the 3800 MHz protection zones. This mask will only apply to base stations operating in the 3800 MHz band around the 35 protected airports until December 31, 2027 to provide a predicable radio frequency environment around these airports. Based on expected 5G deployment scenarios, retaining an airport e.i.r.p. power mask within the exclusion and protection zones until December 31, 2027, around these 35 protected airports, will have negligeable impact on 5G deployments in Canada.

ISED will continue to monitor domestic and international developments on coexistence between 5G operations and radio altimeters.

Decision

ISED sought comments on the proposed technical requirements for flexible use licensees to facilitate coexistence with FSS and FS, as specified in section 5 and in annex B of the Consultation. Comments were provided from various stakeholders related to the 3800 MHz band plan, the 3800 MHz Transition Manual and the coexistence requirements between flexible use, FSS and FS.

Summary of comments on the 3800 MHz band plan

CanWISP urged ISED to extend the definition of the 3800 MHz band to include spectrum in the frequency range 3900-3980 MHz. In addition, CanWISP noted that the operations in the 3900-3980 MHz band must be adequately protected from interference from flexible use operations in the 3450-3900 MHz band.

Summary of comments on the 3800 MHz Transition Manual

Bell, RABC and TELUS believed that WBS stations deployed after a flexible use station should not be protected from existing flexible use stations.

DND requested that Government of Canada (GoC) earth station operations in all areas should be protected.

Rogers and TELUS recommended that the transition manual be published before the auction and allow a comment period for stakeholder feedback.

Summary of comments on tiers impacted by Government of Canada earth station operations

DND, RABC, Telesat, and TELUS suggested replacing table F4 in the draft SRSP with two separate tables to address the impact of GoC earth station operations. One table would contain tiers impacted by earth stations in satellite-dependent areas that have not transitioned, while the other would contain tiers impacted by earth stations in satellite-dependent areas that have transitioned. This would eliminate the need for unnecessary coordination requests as outlined in section 10.4.3 of the draft SRSP.

Summary of comments on coexistence between flexible use systems in the 3450-3700 MHz band and site-approved non-transitioned FSS earth station operations in the 3700-4200 MHz band

Bell, DND, and Telesat supported ISED's proposed rules for coexistence between flexible use systems in the 3450-3700 MHz band and site-approved non-transitioned FSS earth station operations in the 3700-4200 MHz band, including the 25 km distance notification trigger and an unwanted emission limit of -13 dBm/MHz TRP or total conducted power. In addition, given its earth stations are located in areas where 5G deployment will be limited, DND requested that ISED revise the 3800 MHz Policy Decision to protect DND’s site-approved non-transitioned earth station operations from flexible use operations in the 3450-3700 MHz band even after the FSS transition deadline.

The 5G equipment manufacturers (through the RABC response) and TELUS recommended the removal of the -13 dBm/MHz TRP or total conducted power limit as it may not be feasible and/or could be challenging to meet. However, this removal was opposed by DND and Telesat in their reply comments. TELUS also believed that the requirement to protect earth stations is inconsistent with the 3800 MHz Policy Decision. CECA emphasized the importance of enabling the use of a global ecosystem.

In addition, the 5G equipment manufacturers (through the RABC response) and TELUS recommended replacing the 25 km distance notification trigger with a second pfd notification trigger (varying by earth station elevation angle) that would apply to unwanted emissions falling within the operating band of the non-transitioned FSS earth stations (3700-4200 MHz) in order to reduce unnecessary administrative burden for both flexible use and earth station operators.

Summary of comments on coexistence between flexible use systems in the 3700-3900 MHz band and non-transitioned FSS earth station operations in the 3700-4200 MHz band

The respondents generally agreed with ISED’s proposal to adopt the pfd coordination triggers based on earth station elevation angles for the coexistence between flexible use systems in the 3700-3900 MHz band and non-transitioned FSS earth station operations in the 3700-4200 MHz band.

However, some had different views on the interference-to-noise (I/N) criteria of -10 dB used by ISED for co-channel protection of earth stations. DND had concerns regarding the aggregation of all emissions, while Telesat proposed a stricter I/N of -12 dB to take into account interference from unwanted emissions. Bell recommended that the pfd levels proposed by ISED be relaxed by 3 dB based on FCC earth station assumptions (i.e. an earth station noise temperature of 142.8 K, an I/N of -6 dB and a -4dB margin for aggregate impact).

Summary of comments on coexistence between flexible use systems in the 3700-3900 MHz band and site-approved or generic FSS earth stations licensed only in the 4000-4200 MHz band

Bell, CECA, MIG, Rogers, SaskTel, and TELUS expressed concerns about the potential administrative burden under ISED's proposed rules, which would require each flexible use operator to reach an agreement with each FSS operator prior to deployment of any flexible use station within a 25 km radius of a transitioned FSS earth station. These respondents and 5G manufacturers (through the RABC response) recommended that ISED replace the 25 km coordination trigger distance with a second pfd limit that would apply to unwanted emissions falling within the operating band of the FSS earth stations (4000-4200 MHz). A formula-based approach to calculate the pfd, which would vary by the earth station antenna gain (see Recommendation ITU-R S.465-6) and reflected as a lookup table in the SRSP derived using the formula, was recommended by Bell, Rogers, and TELUS in the RABC response. This was further supported by DND and Telesat in a joint agreement between Bell, DND, Rogers, Telesat and TELUS. However, following the joint agreement, TELUS proposed instead an antenna pattern which is a hybrid mask incorporating the Recommendation ITU-R S.465-6 formula for higher elevation angles and a formula equal to Recommendation ITU-R S.580-6 that would apply at lower elevation angles, along with maximum gain (52.6 dBi) outside the applicability of S.580-6 for computing an antenna gain, as well as a transitional (8 dBi) value. There was also no agreement between Bell, DND, Rogers, Telesat, and TELUS on the I/N value and earth station noise temperature to derive the pfd.

Bell and TELUS suggested that the FCC's earth station assumptions used in the US (i.e., an earth station noise temperature of 142.8 K, an I/N of -6 dB and a -4 dB margin for aggregate impact) for coexistence between flexible use operations in the 3700-3980 MHz band and adjacent-band earth station operations in the 4000-4200 MHz band could equally apply to Canada. Telesat did not agree with the FCC's earth station assumptions. Telesat proposed a stricter I/N of -16 dB (or compromise of -14 dB), while maintaining ISED's assumption for receiver noise temperature (70 K). GSOA assumed an I/N of -20 dB in its study, which resulted in their recommendation of an out-of-band emission (OOBE) of -53 dBm/MHz (TRP or total conducted power) to protect FSS earth station operations in the 4000-4200 MHz band.

GSOA’s study also confirmed the benefit of using a filter at earth station receivers to prevent saturation of FSS low-noise block (LNB) downconverters’ saturation, in line with ISED’s proposed filter characteristics in annex G of SRSP-520. However, GSOA proposed that the cost of adapting earth stations with such filters should be compensated.

In addition, RABC members recommended that ISED clarify the proposed text on coordination by noting that both parties are expected to cooperate and jointly resolve any issues in a timely manner. Bell additionally recommended that ISED adopt a coordination framework with reasonable timelines.

Summary of comments on coexistence between flexible use systems in the 3700-3900 MHz band and fixed services in the 3700-3900 MHz band

DND proposed modifying coexistence rules to align with the draft SRSP and putting the responsibility on flexible use licensees to contact and coordinate with existing licensees. DND committed to disclose necessary information for its fixed system to be protected through the coordination process.

Summary of comments on international (CANADA/US) coordination

TELUS proposed a higher pfd limit of -85.7 dBW/m²/MHz at 3 metres above the border for flexible use to flexible use coordination, which accounts for synchronized operations, in addition to the pfd limit proposed by ISED for unsynchronized operations.

Bell, RABC, and TELUS recommended an increase in the pfd limit as measured at the earth station antenna for fundamental (in-band) emissions to -6.2 dBW/m²/MHz for flexible use to FSS earth station coordination. This would align with ISED’s proposal for domestic coordination.

Discussion

Discussion on the 3800 MHz band plan

ISED will develop a separate SRSP to address the non-competitive local (NCL) licensed systems in the 3900-3980 MHz (3900 MHz) band. In addition to the development of this new SRSP, ISED will also address the coexistence between 3900 MHz NCL licensed systems and 3800 MHz flexible use systems in SRSP-520.

Discussion on the 3800 MHz Transition Manual

Although out-of-scope for the present consultation, ISED will take into account the comments received on the 3800 MHz Transition Manual in its development.

Discussion on tiers impacted by Government of Canada earth station operations

Since the original release of SPB-002-22, ISED has updated its published list of Tier 4 service areas where more than 10% of the population is encumbered. To reflect this update, which considers the impact of clutter, ISED has also updated the list of tiers impacted by GoC earth station operations as in annex F. Notably, tier area 4-059 (Notre-Dame-du-Nord) has been removed from the list, while tier area 4-100 (Sudbury) has been added to it.

ISED notes that GoC has the option to transition its earth stations to the 4000-4200 MHz band any time either before or after the FSS transition deadline in satellite-dependent areas. Through coordination, it would be possible for flexible use licensees to identify which GoC earth stations fall in-band or adjacent-band to their operations, instead of relying on ISED to maintain an up-to-date list of transitioned GoC earth stations. This approach would mitigate the risk of a flexible use licensee misidentifying an earth station as either in-band or adjacent-band, given that a table of transitioned earth stations (as proposed by some respondents) may not be updated in real-time.

Discussion on FSS earth station assumptions

In terms of assumptions to derive the pfd values used to trigger notification or coordination (as applicable), ISED has decided to adopt a comprehensive approach taking into account the range of proposals and associated parameters submitted by various respondents.

With respect to the earth station receiver noise temperature, ISED acknowledges that the noise temperature for FSS systems in Canada could vary depending on a number of factors (e.g. antenna elevation angle). For the purposes of triggering notification or coordination between flexible use systems and FSS earth stations in these bands, ISED has decided to assume a value of 70K based on existing earth station licences.

Similarly, concerning the I/N value to enable in-band and adjacent-band coexistence between flexible use and FSS earth station operations, ISED notes again the divergent views by commenters. In an effort to achieve a balance between the various views, ISED has decided to assume an I/N value of -10 dB, combined with a system noise temperature of 70K, to trigger in-band and adjacent-band notification or coordination between the impacted parties.

The above assumed values represent an approach to address the specific issues in Canada, taking into account various factors and proposals received. These values are not necessarily applicable in other bands or under other scenarios.

Finally, ISED notes that the pfd values are to be used to trigger notification or coordination. However, as is the case in any coordination process for all services, ISED expects that the coexistence assessment consider actual deployment parameters and equipment specifications for the successful sharing of these frequency bands. Moreover, the affected parties should work cooperatively to resolve any potential interference issues.

Discussion on flexible use coexistence with in-band FSS earth stations

As there was general agreement on the proposed pfd triggered coordination approach in section 10.4.2 of the SRSP, ISED will maintain this coordination approach.

Discussion on flexible use coexistence with adjacent-band FSS earth stations

In paragraph 251 of the 3800 MHz Repurposing Decision, ISED recognized that implementing technical rules to protect FSS earth stations from adjacent-band flexible use systems in the 3450-3700 MHz band could potentially limit access to equipment and deployment of future flexible use operations in the long-term. Consequently, ISED decided that licensed FSS earth stations will not be protected from interference caused by adjacent-band flexible use operations after the FSS transition deadline. ISED would like to clarify that the 25 km distance notification trigger of D28 of the 3800 MHz Repurposing Decision was based on the RSS-192, issue 4 out-of-band emission limit of -13 dBm/MHz TRP or total conducted power for flexible use stations operating in the 3450-3650 MHz band.

As the band edge for flexible use has now shifted to 3900 MHz, ISED has decided that it is more appropriate to only require flexible use stations to meet the more relaxed out-of-block limits in RSS-192, issue 5, at 3700 MHz. This decision aligns with our objective to avoid limiting access to global equipment ecosystem and deployment of future flexible use operations in the 3650-3700 MHz band. ISED will remove the requirement for fixed and base stations, whose licensed frequency blocks do not extend above 3700 MHz, to meet an unwanted emission limit of -13 dBm/MHz TRP or total conducted power above 3700 MHz in the SRSP. As a result, the 25 km distance notification trigger will be replaced by a second pfd notification trigger (which applies to all emissions within the earth station’s authorized band of operation, 3700-4200 MHz) that will be varied by earth station elevation angle. This change will still enable the identification of earth stations for which operators will need to be notified and allow flexible use licensees to better identify earth stations that may be interfered with.

In addition, ISED will replace the 25 km distance coordination trigger for the coexistence between flexible use operations in the 3700-3900 MHz band and FSS earth station operations in the 4000 4200 MHz band with a second pfd notification trigger (which applies to all emissions within the earth station’s authorized band of operation, 4000-4200 MHz) that will be varied by earth station elevation angle. ISED agrees with the comments received that this change will serve the same purpose as the 25 km coordination distance trigger, while reducing the number of unnecessary coordination requests that could have been burdensome to both flexible use and FSS earth station licensees.

However, ISED will not adopt a more stringent OOBE as proposed by GSOA. ISED notes that there is a 100 MHz frequency separation between FSS operations in the 4000-4200 MHz band and flexible use operations in the 3800 MHz band, as opposed to the 20 MHz frequency separation in the GSOA study. ISED is of the view that the unwanted emission limit for flexible use systems above 4000 MHz will be well below the regulatory limit of -13 dBm/MHz and will be sufficient to protect earth station operations above 4000 MHz.

Discussion on flexible use coexistence with fixed service

ISED recognizes that coexistence with other services in the SRSP requires flexible use licensees to coordinate with existing licensees. However, in alignment with the 3800 MHz Repurposing Decision, ISED maintains that the responsibility for “initiation” of coordination within the tier of DND’s fixed point-to-point operations should be delegated to DND. This simplifies the coordination process given the limited number of fixed point-to-point licenses, the likelihood of a limited number of flexible use licensees deploying with the impacted tier, and the non-disclosure of DND station information. Additionally, this allows DND to disclose its station information only when necessary. It is recommended that, upon announcement of the 3800 MHz auction winners, DND proactively reach out to the flexible use licensees of the impacted tier to obtain information regarding the flexible use licensees’ deployment plans.

Discussion on international (CANADA/US) coordination

ISED acknowledges the feedback received on the matter of international coordination, and we will consider it in ISED’s decision-making process. However, it should be noted that the international coordination rules will be contingent upon negotiations with the US Federal Communications Commission (FCC) and that all licensees are required to comply with any requirements, as specified by ISED, as a result of the international coordination process.

Decision

In the Consultation, ISED sought comments on the proposed changes to the RSS, specified in section 6 and annex C of the Consultation.

In the proposed changes to the RSS, ISED included a spurious (unwanted) emission limit of -33 dBm/MHz in the 4200-4400 MHz band, the operating band of radio altimeters, in order to minimize the potential of harmful interference to radio altimeters.

In addition, ISED proposed to increase the limit for indoor base stations from 33 dBm to 39 dBm TRP and proposed to revise the limit for subscriber equipment other than fixed subscriber equipment from 23 dBm/10 MHz to 30 dBm e.i.r.p. per channel bandwidth. Comments were provided on these amendments, including out-of-band emission limits of equipment and the transition period between issue 4 and issue 5 of the RSS.

Summary of comments on spurious emissions in the 4200-4400 MHz band

The majority of stakeholders who responded to this proposed change did not support ISED’s proposal for a spurious emission limit of -33 dBm/MHz in the 4200-4400 MHz band.

Stakeholders from the telecommunications industry which included Bell, MIG, RABC, Rogers, Sasktel and TELUS, suggested ISED should adopt a spurious emission limit of -30 dBm/MHz instead of -33 dBm/MHz. In their comments, these stakeholders highlighted that 5G base stations transmit using two polarizations while radio altimeter antennas detect only one polarization, which means that a signal received by a radio altimeter antenna from a 5G base station would be 3 dB lower in power. Therefore, they suggested that a spurious emission limit of -30 dBm/MHz for a base station, which would translate to -33 dBm/MHz for the radio altimeter, would be a more suitable limit. In their reply comments, Bell and Rogers were of the view that the -48 dBm/MHz limit is excessive. Bell highlighted that the spurious emission limit must not be set lower than necessary to protect radio altimeters and not lower than the level at which equipment manufacturers can comply using their existing equipment.

In contrast, the Coalition and DHC recommended that ISED consider -48 dBm/MHz. DHC highlighted that the FAA and radio altimeter suppliers have conducted analysis and testing which determined that if spurious emissions are controlled to -48 dBm/MHz at the base station, radio altimeters should be able to perform without interference.

TC requested that ISED establish an approach to limiting spurious emissions that meets a comparable level of safety and security for the aviation industry, as established in the US.

Discussion

ISED recognizes that 5G equipment is designed to meet international regulatory requirements, including specifications set forth in industry standards. For instance, the 3rd Generation Partnership Project (3GPP) standard body specifies two categories of equipment that meet either a -13 dBm/MHz or -30 dBm/MHz spurious emissions limit in frequency bands above 1 GHz (as specified in TS 38.104). Equipment meeting a -30 dBm/MHz limit is typically adopted in equipment deployed in European markets to meet European regulatory requirements, while a -13 dBm/MHz limit is for North American markets to meet Canadian and US regulatory requirements.

In the US, the FAA secured a voluntary agreement with the four largest mobile operators to deploy base stations with spurious emission levels of -48 dBm/MHz or less in the 4200-4400 MHz band. This -48 dBm/MHz spurious emission level includes a 6 dB aviation safety margin and an additional 6 dB margin to account for aggregate emissions from multiple base stations (see FAA NPRM, Airworthiness Directives; Various Helicopters).

ISED notes that the agreement between the FAA and the four US mobile operators is a voluntary operational specification rather than a regulatory certification requirement mandated by the US spectrum regulator, the FCC. ISED also notes that the FCC has not adopted a more stringent spurious emission limit, as -13 dBm/MHz remains the current regulatory limit. If ISED were to adopt a limit of -48 dBm/MHz as part of the certification process for 5G base stations, it could result in a Canadian-only ecosystem, leading to higher cost of 5G services for Canadians.

In order to address the comments received by stakeholders, ISED conducted a detailed technical review of all radio altimeter susceptibility data, assessed the feasibility of constructive multipath and base station signal aggregation, and conducted additional analyses and simulations to model base station spurious emissions in three-dimensional space.

ISED reviewed its own laboratory results and radio altimeter manufacturer data, and compared it with new data shared by TC. TC’s data included margins for unit-to-unit and temperature variance. ISED found that its original ITM, described in annex A of the Consultation, sufficiently captured the performance of all radio altimeters for which ISED had data.

ISED is of the view that an additional safety margin of 6 dB was not required in its computational analysis. The ICAO Handbook notes that a minimum 6 dB safety margin is generally required to account for risk that some factors cannot be foreseen or quantified (e.g. aggregate emissions). In its computational model, ISED made multiple additive worst-case assumptions to minimize the risk of harmful interference between 5G operations and radio altimeters. ISED did not include factors that would have improved coexistence between 5G systems and radio altimeters, such as typical digital tilt of base station which limits skyward antenna lobes (up to 3 dB), base station Time Division Duplex (TDD) duty cycle (up to 3 dB) and typical traffic load (up to 3 dB), and polarization losses (up to 3 dB). Moreover, ISED’s computational analysis model assumed that the following events would all occur at the same time: worst-case antenna coupling, spurious emissions magnitude, base station antenna pointing angle and radio altimeter loop loss factor. The omission of factors that would improve coexistence and the assumption of worst-case events occurring simultaneously provided a safety margin significantly higher than the ICAO 6 dB safety margin.

ISED conducted additional analysis to assess whether constructive multipath and the aggregation of base station emissions could increase the probability of harmful interference. ISED concluded that it is not appropriate to apply two independent margins of 3-6 dB for constructive multipath and 6 dB for aggregation of base station emissions as it is implausible for these two factors to occur simultaneously. ISED concluded that constructive multipath would not increase the probability of harmful interference. ISED’s computational analysis showed that peak emissions from a single base station occur in close proximity to the base station (e.g. 10 metres (32.8 feet) horizontal separation of an aircraft). A 3 dB enhancement in constructive multipath requires the line-of-sight (LOS) and non-LOS signals to be equal in magnitude, which in close proximity is unlikely. Further, ISED did not see any evidence of constructive multipath in its deployment model with raytracing when the aircraft and base station were in close proximity. For an aggregate interference enhancement of 6 dB, the signal contributions from 4 base stations would need to have identical amplitudes at the victim receiver, which is highly unlikely. For example, base stations deployed by different operators will have different pointing (azimuth and elevation) angles, be physically separated and operate at different operational powers. In addition, deployment data in ISED’s Spectrum Management System database indicates that the maximum number of Canadian operators on a tower is two, with the vast majority of deployments having a single operator at a particular location.

Further, ISED identified and modelled three scenarios to assess the aggregation of spurious emissions:

1. a one-operator three-sector deployment using typical antenna tilt angles
2. two three-sector deployments representing two operators at the same tower using typical antenna tilt angles
3. a one-operator three-sector base station deployment with antenna tilt angle generating worst case skyward lobes

The results of these latest simulations, which included base station aggregation, continued to align with the original findings described in annex A of the Consultation. For all three scenarios, the results showed that the ITM would not be exceeded with a -30 dBm/MHz spurious emission level for a vertical separation of 50 feet (15.2 metres) between the base station and the aircraft. Specifically, the one operator three-sector base station deployment operating with a typical antenna digital tilt, did not exceed the ITM at 35 feet (10.67 metres) of vertical separation with a -30 dBm/MHz spurious emissions level. For the two-operator scenario and the one-operator scenario with worst-case skyward lobes, the ITM could only theoretically be exceeded when the aircraft’s physical location is within a horizontal separation of 5 metres (16.4 feet) from the base station, which is highly unlikely.

Further, ISED notes that 3GPP base stations typically operate below the regulatory limits imposed through equipment certification. For example, in the National Telecommunications and Information Administration (NTIA) report, Measurements of 5G New Radio Spectral and Spatial Power Emissions for Radar Altimeter Interference Analysis, Joint Interagency 5G Radar Altimeter Interference (JI-FRAI) over-the-air (OTA) measurements showed that the spurious emissions of 5G base stations were far below the regulatory limit of -13 dBm/MHz. This observation was confirmed for other 3GPP equipment in other NTIA analyses (see NTIA Technical Report TR 15-512 and TR 18-528). Therefore, equipment in compliance with a -30 dBm/MHz regulatory limit will generate spurious emission levels less than the regulatory limit. ISED also notes that the base stations evaluated in the JI-FRAI OTA test – available from major vendors – would likely be deployed in Canada by the larger mobile network operators.

While adopting a -48 dBm/MHz limit would offer an additional margin of protection, ISED is of the view that this spurious emission limit is not technically warranted and could create a Canadian-only regulatory requirement. Based on ISED’s analysis, a -30 dBm/MHz spurious emission limit provides sufficient protection from harmful interference. This value is aligned with 3GPP and European requirements, which will allow Canadian service providers to leverage a global ecosystem, including economies of scale.

Summary of comments on the power limit for indoor base stations and subscriber equipment

Comments were received from Bell, MIG, Rogers, and TELUS. All commenters supported the proposed revision to the limit for indoor base stations from 33 dBm to 39 dBm TRP and the limit for subscriber equipment other than fixed subscriber equipment from 23 dBm/10 MHz to 30 dBm per channel bandwidth.

Discussion

ISED will adopt the proposed power limits for indoor base stations and subscriber equipment. These limits are closely harmonized with the US requirements, which will allow Canada to take advantage of economies of scale. Moreover, the increased power limits will result in increased performance and coverage for users.

ISED also received comments on other technical requirements within the proposed RSS-192.

Summary of comments on out-of-band emission limits for outdoor base stations, point-to-point and point-to-multipoint equipment

In their comments, Bell and TELUS recommended ISED extend the frequency range from 3900 MHz to 3980 MHz for the unwanted emission limits for outdoor base stations, and point-to-point (P-P) and point-to-multipoint (P-MP) equipment in the 3450-3900 MHz frequency range. TELUS suggested that the -13 dBm/MHz limit be applied above 3980 MHz instead of 3900 MHz and that the limit found in table 2 of annex C would be applied above 3900 MHz.

The People’s Republic of China suggested that the out-of-band emission limit at the upper edge of the band be a step function limit, similar to the one proposed in table 2 of annex C of the Consultation, where the -13 dBm/MHz limit would be applied above 3940 MHz instead.

Discussion

ISED notes that the unwanted emission limit of -13 dBm/MHz for outdoor base stations, and P-P and P-MP equipment above 3900 MHz is aligned with the FCC limit for out-of-block emissions. This limit will allow for better coexistence with future non-competitive local licensing operations in the 3900-3980 MHz band. Consequently, no changes will be made to the proposed limits in this frequency range.

Summary of comments on out-of-band emission limits for indoor base stations

The MIG, RABC, Rogers, Sasktel and TELUS recommended that the -30 dBm/MHz limit for unwanted emissions for indoor base stations apply above 3980 MHz rather than 3910 MHz. They highlighted that the proposed recommendation would make a broad indoor base station ecosystem available to the Canadian service providers, including those designed for the US market. TELUS further recommended that the unwanted emission limit in table 5 of annex C of the Consultation only apply to frequencies below 3440 MHz.

The Aviation Coalition, in its comments, recommended ISED work with TC to determine if the -30 dBm/MHz limit could be considered an acceptable limit for unwanted emissions for indoor base stations by taking into account propagation loss and other losses due to physical obstructions, which would translate to an outdoor level of -48 dBm/MHz in the 4200-4400 MHz band.

Discussion

The out-of-block limit for indoor base stations is a step function as specified in table 5 of annex C of the Consultation, with a value of -27 dBm/MHz for an offset of more than 5 MHz. In addition, the spurious emission of -30 dBm/MHz is currently applied to frequencies above 3910 MHz, 10 MHz from the edge of the band. These limits are in alignment with 3GPP transmitter spurious emission limits. ISED recognizes that the adoption of an unwanted emission limit of -30 dBm/MHz above 3980 MHz, instead of 3910 MHz, would allow Canadian service providers to benefit from the indoor base station ecosystem including those designed for the US market. In this case, the risk of interference from indoor base station to future non-competitive local licensing outdoor equipment operating in the 3900-3980 MHz band remains minimal, as the losses from building material and clutter would attenuate the signal significantly.

Summary of comments on the transition period between issue 4 and issue 5 of RSS-192

The People’s Republic of China requested a transition period of 18 months to provide time for manufacturers and test labs to adapt to the new regulatory requirements for obtaining certification.

Discussion

ISED recognizes that a longer transition period would allow test labs to adapt to the new regulatory requirements. However, a six-month transition period is consistent with previous revisions made to other Radio Standards Specifications (RSS) to allow the new deployment of the latest technologies on the Canadian market.

ISED has updated the current SRSP-520, issue 2 and RSS-192, issue 4, in accordance with this decision, which is published as SRSP-520, issue 3, Technical Requirements for Fixed and/or Mobile Systems, Including Flexible Use Broadband Systems, in the Band 3450-3900 MHz and RSS-192, issue 5, Flexible Use Broadband Equipment Operating in the Band 3450-3900 MHz.

All spectrum-related documents referred to in this paper are available on ISED's Spectrum management and telecommunications website.