IMT: How technical uniformity of standards will guarantee aviation security

Air transport plays a major role in driving sustainable economic and social development in Nigeria. Since the mid-1970s, air traffic growth has defied economic recessionary cycles, expanding two-fold once every 15 years. In 2012, air transport directly and indirectly supported the employment of 56.6 million people worldwide, contributing over $2 trillion to global Gross Domestic Product (GDP), and carried over 2.5 billion passengers and $5.3 trillion worth of cargo. The Nigerian airspace is becoming more complex and the demand for frequency assignments is increasing. While some of this demand canAir transport plays a major role in driving sustainable economic and social development in Nigeria. Since the mid-1970s, air traffic growth has consistently defied economic recessionary cycles, expanding two-fold once every 15 years. In 2012, air transport directly and indirectly supported the employment of 56.6 million people worldwide, contributing over $2 trillion to global Gross Domestic Product (GDP), and carried over 2.5 billion passengers and $5.3 trillion worth of cargo. The Nigerian airspace is becoming more complex and the demand for frequency assignments is increasing. While some of this demand can be met through improved spectral efficiency of existing radio systems in frequency bands currently allocated to aeronautical services, it is inevitable that these frequency bands may need to be increased or additional aviation spectrum allocations may need to be agreed to meet this demand.

According to the Nigerian Civil Aviation Authority, NCAA, release, a number of aviation systems used for assurance of flight safety are operating below 6 000 MHz, and it is therefore essential to ensure that any new allocation to the mobile service does not adversely impact the operation of these systems. Based on recent experience with the introduction of mobile systems in the frequency band below 2 690 MHz and interference to primary surveillance radar systems in the adjacent band (2 700 – 2 900 MHz), care needs to be taken not only with any proposal for co-frequency band sharing of aeronautical services with non-aeronautical services but also with proposals for the introduction of new allocations in frequency bands, the statement said.

Radio-determination systems
The federal agency believes that studies carried out based on the parameters provided by ITU-R show that within the same geographical area, co-frequency operation of mobile broadband systems and radar is not feasible. Furthermore, there is widespread usage of this frequency range for radar systems. In addition, harmonized usage of all or a portion of this frequency range by the Mobilw System for the implementation of IMT may not be feasible, in particular on a global basis.
It however, says that studies conducted in ITU-R were between IMT base stations and UE and all relevant types of radar systems, as well as radar systems into IMT base stations and UE. The results show that sharing between IMT and land based Radar B is not feasible in the same geographical area.

In addition, studies also concluded that sharing between IMT and airborne Radar A is not feasible in the same geographical area. For one study sharing between IMT indoor and land based Radar A was shown to be possible with a separation distance up to 1.1 km. However two other studies showed that sharing would not be possible unless a separation distance from 25 to 45 km is maintained.

Aeronautical mobile systems and IMT
So far, in terms of co-channel interference, one sharing study shows large separation distances are required to protect certain types of AMS stations. In the case of protecting airborne station receivers from a single IMT base station interference, the protection distances vary between 162-509 km for aircraft altitude of 2.4 km and 19 km respectively. In the case of protecting airborne station receivers from IMT base station aggregated interference the protection distances range from 446-706 km for aircraft altitudes at 2.4 km and 19 km respectively. In this case, the corresponding protection zones encompass an area of about 623 318 km2 and 1.5 million km2, respectively. Based on this analysis, co-channel sharing between aeronautical mobile applications and IMT systems in 4 400-4 990 MHz is not practical in the geographic areas located within the required exclusion zones of up to 706 km.

The Nigerian Civil Aviation Authority, NCAAS, is of the view that the adjacent channel study assumes that incumbent systems for aeronautical/ground mobile applications do not use the entire 4 400-4 990 MHz frequency band and there could be free spectrum available to implement potential IMT systems using the adjacent channel solution in this band. Also, if systems in incumbent services, the FS and the MS, currently use the entire band, the use of adjacent channel solutions would result in a loss of spectrum for these services, which may impact operations and future planning for the incumbent services. Some administrations are of the view that the use of an adjacent channel solutions for IMT may be feasible in some countries due to incumbent aeronautical/ground mobile applications not using the entire 4 400-4 990 MHz band.
be met through improved spectral efficiency of existing radio systems in frequency bands currently allocated to aeronautical services, it is inevitable that these frequency bands may need to be increased or additional aviation spectrum allocations may need to be agreed to meet this demand.

According to the Nigerian Civil Aviation Authority, NCAA, release, a number of aviation systems used for assurance of flight safety are operating below 6 000 MHz, and it is therefore essential to ensure that any new allocation to the mobile service does not adversely impact the operation of these systems. Based on recent experience with the introduction of mobile systems in the frequency band below 2 690 MHz and interference to primary surveillance radar systems in the adjacent band (2 700 – 2 900 MHz), care needs to be taken not only with any proposal for co-frequency band sharing of aeronautical services with non-aeronautical services but also with proposals for the introduction of new allocations in frequency bands, the statement said.

Radio-determination systems
The federal agency believes that studies carried out based on the parameters provided by ITU-R show that within the same geographical area, co-frequency operation of mobile broadband systems and radar is not feasible. Furthermore, there is widespread usage of this frequency range for radar systems. In addition, harmonized usage of all or a portion of this frequency range by the Mobilw System for the implementation of IMT may not be feasible, in particular on a global basis.
It however, says that studies conducted in ITU-R were between IMT base stations and UE and all relevant types of radar systems, as well as radar systems into IMT base stations and UE. The results show that sharing between IMT and land based Radar B is not feasible in the same geographical area.

In addition, studies also concluded that sharing between IMT and airborne Radar A is not feasible in the same geographical area. For one study sharing between IMT indoor and land based Radar A was shown to be possible with a separation distance up to 1.1 km. However two other studies showed that sharing would not be possible unless a separation distance from 25 to 45 km is maintained.

Aeronautical mobile systems and IMT
So far, in terms of co-channel interference, one sharing study shows large separation distances are required to protect certain types of AMS stations. In the case of protecting airborne station receivers from a single IMT base station interference, the protection distances vary between 162-509 km for aircraft altitude of 2.4 km and 19 km respectively. In the case of protecting airborne station receivers from IMT base station aggregated interference the protection distances range from 446-706 km for aircraft altitudes at 2.4 km and 19 km respectively. In this case, the corresponding protection zones encompass an area of about 623 318 km2 and 1.5 million km2, respectively. Based on this analysis, co-channel sharing between aeronautical mobile applications and IMT systems in 4 400-4 990 MHz is not practical in the geographic areas located within the required exclusion zones of up to 706 km.

The Nigerian Civil Aviation Authority, NCAAS, is of the view that the adjacent channel study assumes that incumbent systems for aeronautical/ground mobile applications do not use the entire 4 400-4 990 MHz frequency band and there could be free spectrum available to implement potential IMT systems using the adjacent channel solution in this band. Also, if systems in incumbent services, the FS and the MS, currently use the entire band, the use of adjacent channel solutions would result in a loss of spectrum for these services, which may impact operations and future planning for the incumbent services. Some administrations are of the view that the use of an adjacent channel solutions for IMT may be feasible in some countries due to incumbent aeronautical/ground mobile applications not using the entire 4 400-4 990 MHz band.

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