| 7.1 | Cross Border Frequency Coordination will abide by the Harmonised Calculation Method for Africa (HCM4A) Agreement. This follows the 3rd CRASA AGM that agreed that CRASA should implement the Cross Border Frequency Coordination HCM4A Agreement. |
| 7.2 | The ECC had noted the need for greater understanding of the concept and need for harmonisation in the signing of the HCM4A Agreement by SADC Member States if the implementation of the Agreement was to be effective. The ECC, therefore, agreed to convene a workshop on HCM4A and requested CRASA Members to consider signing the agreement. These activities were part of the Frequency Planning Sub Committee (FPSC) Operations Plan 2015/16. |
| 7.3 | At the 5th CRASA AGM, Swakopmund, Namibia – 07-08 April 2016, the subject of Cross Border Frequency Coordination using the HCM4A was discussed in detail, following similar efforts in Europe8. The Resolution CRASA/AGM/15.16/07 stipulates “The AGM urged CRASA Members to prioritise the motivation to their administrations who are yet to indicate their interest to sign the Harmonised Calculation Method for Africa (HCM4A), to do so as soon as possible”. |
| 7.3.1 | Therefore, coordination would follow the HCM4A as detailed in HIPSSA9. |
| 7.4 | A harmonised calculation method (HCM4A10) brings these benefits. |
| 7.4.1 | Based on HCM Agreement used in Europe, also under ITU Region 1; |
| 7.4.2 | Optimise spectrum usage; |
| 7.4.3 | Prevent harmful interferences; |
| 7.4.4 | Confer an adequate protection for stations; |
| 7.4.5 | Define technical provisions and administrative procedures; |
| 7.4.6 | Quick assignment of preferential frequencies; Transparent decisions through agreed assessment procedures; Quick assessment of interference through data exchange. |
| 7.5 | HCM4A involves all four (4) sub-regions of Africa. This means the HCM4A project includes performing a survey and a comparative analysis of existing administrative and technical procedures related to bilateral and multilateral cross-border frequency coordination agreements across the four (4) geographical sub-regions as defined by the AU namely: |
| 7.5.1 | Central Africa: [Burundi, Central African Republic, Chad, Congo, Democratic Republic of Congo, Equatorial Guinea, Gabon, Sao Tome, and Principe]; |
| 7.5.2 | East Africa: [Comoros, Djibouti, Eritrea, Ethiopia, Kenya, Madagascar, Mauritius, Rwanda, Seychelles, Somalia, Sudan, Tanzania, Uganda]; |
| 7.5.3 | Southern Africa: [Angola, Botswana, Lesotho, Malawi, Mozambique, Namibia, South Africa, Swaziland, Zambia, Zimbabwe]; |
| 7.5.4 | West Africa: [Benin, Burkina-Faso, Cape Verde, Côte d’Ivoire, Gambia, Ghana, Guinea, Guinea-Bissau, Liberia, Mali, Niger, Nigeria, Sierra Leone, Senegal, Togo] |
| 7.6 | HCM4A also comes with a software tool for the coordination of the spectrum resources in Sub- Saharan Africa in order to:11. |
| 7.6.1 | Optimise spectrum usage by accurate interference field strength calculations; |
| 7.6.2 | Establish general parameters, improvement, and supplementation of technical provisions, individual restrictions; |
| 7.6.3 | Establish models for computer-aided interference range calculations; |
| 7.6.4 | Harmonise parameters: objectively predictable towards transparent decisions. |
| 7.7 | Use of these frequency bands shall require coordination with the neighbouring countries within the coordination zones of 6 kilometres in case of LTE-to-LTE or 9 kilometres in case of LTE-to-other technologies from the neighbouring country. The coordination distance is continuously being reviewed and may be updated from time to time. |
| 7.8 | The following field strength thresholds have to be assured based on ECC/REC (08)0212 for 900 MHz band and ECC/REC (11)04 for 790 MHz – 862 MHz applied to the 900 MHz band. Operator-to-operator coordination may be necessary to avoid interference. |
| 7.9 | In general stations of FDD systems may be used without coordination with a neighbouring country if the mean field strength produced by the cell (all transmitters within the sector) does not exceed the value of 55 dBμV/m/5 MHz at a height of 3 m above ground at the border line between countries and does not exceed a value of 29 dBμV/m/5 MHz at a height of 3 m above ground at a distance of 9 km inside the neighbouring country. |
In the case that LTE is deployed on both sides of the border the field strength levels can be increased to 59 dBμV/m/5 MHz at the border (0 km) and 41 dBμV/m/5 MHz13 at 6 km from the border line inside the neighbouring country for preferential PCI codes (discussed in Appendix C), also measured at a height of 3 m above ground. For the use of non-preferential PCI codes and aligned centre frequencies, the trigger field strength level is 41 dBμV/m/5 MHz at the border.
| 7.10 | As per ECC/REC (11)04, if TDD is in operation across both sides of a border and is synchronised across the border, then field strength levels are the same as for the LTE-to-LTE coordination case. For unsynchronised TDD, the trigger field strength level is 24 dBμV/m/5 MHz at the border. |
For field strength predictions the calculations should be made according to Appendix B. In cases of other frequency block sizes 10*log10 (frequency block size / 5 MHz) should be added to the field strength values e.g.:
Table 2: Field Strength Adustments
If neighbouring administrations wish to agree on frequency coordination based on preferential frequencies, while ensuring a fair treatment of different operators within a country the Authority will add these mutual agreements.
As per ECC/REC (11)0415, stations of IMT systems may be operated without coordination if the mean field strength produced by the cell (all transmitters within the sector) does not exceed the value of 15 dBμV/m/5 MHz at 10% time, 50% of locations at 3 metres above ground level at the border line.
| 7.11 | Technical analysis may be conducted by the Authority before an assignment is issued according to Appendix B based on an extract from ECC/REC (11)05. |
| 7.12 | Specific information regarding coordination is based on an extract from ECC/REC (11)05. |
| 7.13 | In the event of any interference, the Authority will require affected parties to carry out coordination. In the event that the interference continues to be unresolved after 24 hours, the affected parties may refer the matter to the Authority for a resolution. The Authority will decide the necessary modifications and schedule of modifications to resolve the dispute. The Authority will be guided by the Frequency Coordination Process as outlined in Appendix D. |
| 7.14 | Assignment holders shall take full advantage of interference mitigation techniques such as antenna discrimination, tilt, polarization, frequency discrimination, shielding / blocking (introduce diffraction loss), site selection, and/or power control to facilitate the coordination of systems. |
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| 8 | https://www.itu.int/ITU-D/projects/ITU_EC_ACP/hipssa/docs/itu-j-f_le_bihan-presentation_general_du_projet-en.pdf |
| 9 | https://www.itu.int/en/ITU-D/Projects/ITU-ECACP/ |
HIPSSA/Documents/FINAL%20DOCUMENTS/FINAL%20DOCS%20ENGLISH/hcm4a_agreement.pdf.pdf
| 10 | https://www.itu.int/en/ITU-D/Projects/ITU-EC-ACP/HIPSSA/Documents/FINAL DOCUMENTS/FINAL DOCS ENGLISH/hcm4a_agreement.pdf.pdf |
| 11 | PowerPoint Presentation (itu.int) https://www.itu.int/en/ITU-D/Regional-Presence/AsiaPacific/Documents/Events/2017/May%20BKK/Presentations/HCM%20and%20HCM4A%20BKK%20201 70504%20IB.pdf |
| 12 | ECC Recommendation (08)02 “Frequency planning and frequency coordination for GSM / UMTS / LTE / WiMAX Land Mobile systems operating within the 900 and 1800 MHz bands”. Approved 21 February 2008. Amended 27 April 2012 |
| 13 | The trigger value of value of 35 dBμV/m/5 MHz at a height of 3 m above ground at a distance of 9 km inside the neighbouring country, in the frequency band 925 - 960 MHz, used in ECC/REC(08)02 may be shown to be mathematically equivalent to 41 dBμV/m/5 MHz at 6 km from the border line used in ECC/REC(11)04, as 20 x log10 (900 MHz / 700 MHz) + 20 x log10( 9 km / 6 km ) 6 dB = 41 dBμV/m/5 MHz - 35 dBμV/m/5 MHz. |
| 14 | As based on the original release of ECC/REC (11)04 (not the latest one). |
| 15 | Also, per Report ITU-R M.2241 (11/2011): Compatibility studies in relation to Resolution 224 in the bands 698-806 MHz and 790-862 MHz. |
