APT comment to consultation final

Panli

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• Publié par: Idwa
• Nombre de lectures: 30
• Langue: English

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APT SATELLITE CO., LTD 22 Dai Kwai Street, Tai Po Industrial Estate, Tai Po, NT, Hong KongTel: [phone]3038Fax: [phone]7838

April 17, 2009 Mr. T. F.So RSAC Chairman Radio Spectrum Advisory Committee (RSAC) Office of the Telecommunication Authority (OFTA) 29/F, Wu Chung House 213 Queen’s Road East Wanchai Hong Kong Re: Comment on Consultation Paper Creation of a Class Licence for UltraWideband Radiocommunications Devices under Section 7B(2) of the Telecommunications Ordinance (Cap. 106) Ref:“Report on Consultancy Study in relation to Electromagnetic Compatibility of Ultrawideband Radiocommunications Devices” issuedby OFTA in 21 January 2009, referred as“the report” Dear Sir, APT Satellite Company Limited is one of the satellite operators in Hong Kong that would be a major victim of the deployment of UWB service in 3.4 GHz to 4.2 GHz band. The analysis and test detailed in the report have fully proved there is interference from UWB service to FSS. Whether the interference is harmful or not harmful, acceptable or not acceptable is up to further discussion in the current stage. We refer to OFTA’s paper on below 3 issues as: (a) Whether UWB radiocommunications devices should be allowed for use in Hong Kong at this stage APT notes that, no matter OFTA issues UWB license to its users or not, there are more and more UWB devices or applications flowing into Hong Kong IT market. Rather than let it grow out of control, it might be more practical for the government to issue class or individual license, depending on the device type, to the devices or equipments, stating clearly the operational constraints, i.e. the power masks and 10 meter exclusion zone for the FSS earth stations etc.

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APT SATELLITE CO., LTD 22 Dai Kwai Street, Tai Po Industrial Estate, Tai Po, NT, Hong KongTel: [phone]3038Fax: [phone]7838 (b) adoption of generic emission mask and operational criteria of UWB radiocommunications devices including requirements of primarily indoor use and no attachment to a fixed antenna in outdoor use (as proposed in paragraph 6 of RSAC Paper 3/2008) We agree with the approach to set up an emission mask and operational constraints for UWB devices, including the requirement of primarily indoor use and no attachment to a fixed antenna in outdoor use, however, APT believes an appropriate emission mark (70 dbm/MHZ) in 3.44.2 GHz shall be set in order to give enough protection to existing FSS. (c) whether the alternative limit of 41.3 dBm/MHz for the UWB radiocommunications devices employing mitigation techniques should be allowed in the 4.24.8 GHz band or in the 3.44.8 GHz band (as proposed in paragraph 14 of RSAC Paper 1/2009). APT reserves its opinion on the alternative power mask (41.3 dBm/MHz) in the 3.4 GHz to 4.2 GHz band. Specifically in the report, the calculation came to a conclusion that, if UWB devices operate under the power mask of 71.6 dBm/MHz, then the fix satellite service in the overlapping band would not be harmfully interfered. Furthermore, the report proposed a power raise because 1) there is indoortooutdoor attenuation of 1240dB; 2) the field test shows“when the C/I ratio at IF was larger than 16.8 dB (I/N<2dB), no degradation for the Cband satellite receiving station was found”, since the 71.6 dBm/MHz is based on I/N=20 dB, therefore the value 71.6 dBm/MHz should be increased accordingly. APT is of the view that, 1) theworst scenario indoortooutdoor attenuation is 12 dB, then the power mask may be raised from 71.6 dBm to 59.6 dBm/MHz. (refer to Summary in the page 48 of the report) 2) inthe field test, the satellite TV receiver is robust enough to endure a I/N of 2dB, it doesn’t mean all satellite service applications and receivers are able to take this level of interference, there are various of satellite links such as VSAT and satellite IP links that can not work in I/N = 2 dB. The proposed raise due to eased I/N criteria is not acceptable. Although APT can accept 59.6 dBm/MHz as UWB power mask, the following

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APT SATELLITE CO., LTD 22 Dai Kwai Street, Tai Po Industrial Estate, Tai Po, NT, Hong KongTel: [phone]3038Fax: [phone]7838

conditions (as described in the report) should be maintained in the UWB deployment: 1) Low Duty Cycle (LDC) and Detect and Avoid (DAA) techniques are adopted for the UWB device. APT notes that, the current LDC and DAA are not designed for protecting FSS, more study should be done on this subject. 2)10 meter exclusion zone for Cband satellite receiving system. The field test detailed in the report has proved a UWB device can cause significant interference to the satellite receiving system when it is put in the 10 meter exclusion zone. APT sees no difficulty for the UWB device holder to identify a satellite receiving system (a“satellite dish”is easy to spot by any UWB user), therefore we propose the 10 meter exclusion zone idea should be introduced into the future UWB license scheme. Especially in the preliminary phase of UWB deployment, most UWB devices are fixed or attached with no mobile ability, for them, it is simple for OFTA to enforce the 10 meter exclusion zone policy. As more mobile UWB devices flows to Hong Kong market, OFTA can either ask the UWB user to watch out the satellite dishes when they move around in the territory, or OFTA can enforce a uniform emission mask of 70 dBm/MHz to protect the FSS in close proximity. APT suggests adopting the emission mask tighter than 41.3 dBm/MHz at this stage for the purpose of protecting FSS in the 3.44.2 GHz band. After more study is done in the subject and less occurence of the real interference case after UWB massive deployment, it becomes reasonable to relax the emission mask if it’s applicable. Sincerely yours, APT Satellite Co., Ltd

______________ Pan Li Senior Spectrum Engineer

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