1、 Rep. ITU-R M.2080 1 REPORT ITU-R M.2080 Consideration of sharing conditions and usage in the 4-10 MHz band (2006) Scope In preparing the text for the draft CPM-07 Report, there were a number of input documents providing information on sharing conditions in the 4-10 MHz band. Although these document
2、s have been taken into account in the revision of the draft CPM text for WRC-07 Agenda item 1.13, they contain valuable information for ITU-R studies in HF bands and have been used to create a new Report. Introduction This Report gathers together texts submitted during the study period 2003-2007. Do
3、cuments referenced are from this study period unless otherwise indicated. These texts address sharing issues between various allocated services and other information on the use in the HF bands. During the discussions on the various input documents, diverging views on the conclusions of the input doc
4、uments were expressed by some administrations. Structure of the Report On the following pages an executive summary is given for each annex. Following this summary two views are expressed: View I represents comments supporting the conclusions of the study contained in the annex. View II represents th
5、e comments contrary to the conclusions of the study contained in the annex. In order to have a complete understanding on the issues both views and the relevant annexes must be read. 2 Rep. ITU-R M.2080 TABLE OF CONTENTS Page Annex 1 Information on feasibility of frequency sharing between different r
6、adiocom-munication services in the frequency range 4-10 MHz 10 Annex 2 Spectrograms from monitoring campaigns 27 Annex 3 Sharing analysis of specific sharing conditions in the 4-10 MHz band. 44 Annex 4 HF compatibility considerations 62 Annex 5 Spectrum sharing considerations in relation to Agenda i
7、tem 1.13 WRC-07 . 71 Annex 6 Considerations regarding a primary fixed service or mobile service allocation and secondary amateur service allocation within the same band. 76 Rep. ITU-R M.2080 3 EXECUTIVE SUMMARY Annex 1 Information on feasibility of frequency sharing between different radiocommunicat
8、ion services in the frequency range 4-10 MHz Analysis shows that proposed sharing between adaptive systems in the fixed and maritime mobile services would result in unacceptable and harmful interference between these services. Although constraints could be applied to the fixed service to reduce this
9、 interference it would prevent optimal operation of that service. The analysis also shows that the use of narrow-beam antennas in the frequency range 4 to 10 MHz is impractical as a means of establishing compatibility between these services. View I The Annex considers an analysis of long-range commu
10、nications using multi-hopping techniques. The results of evaluation clearly show that the increasing of antenna gain or its directivity is not the key factor which permits to improve the sharing between the services due to multiple reflection from ionosphere. The Annex clearly shows that the impleme
11、ntation of the frequency-adaptive systems resulting in the usage of the same frequency at the same time and at the same area by the different systems will result in harmful interference between services. Therefore sharing between services could cause unacceptable and harmful interference. That is wh
12、y the satisfaction of the increasing requirements of any service should be realized by the improvement of the existing systems in the interested service and without prejudice to other services. View II Sharing between services is already included in the procedures of the Radio Regulations, establish
13、ed techniques developed in ITU-R through various WRC Resolutions and ITU-R Recommendations. Taking into account the dimensions of frequency, time, and space in use of HF services, compatible and more efficient operation in the HF bands is feasible when bands are allocated for shared use. This Annex
14、does no more than state the obvious fact that trying to make use of the same frequency to provide communications at the same time to the same general location will fail. This observation is extended to construct an argument that consolidates frequency use over a 24-hour period and concludes that no
15、inter or intra service sharing is possible. The type of links analysed have powers and coverage areas that would not be out of place in broadcast planning and are not typical of the short duration point to point links that characterize many of todays data exchange functions. Neither do the analyses
16、recognize that even a single HF frequency can be reused at the same time if care is taken to ensure that sufficient isolation is obtained through a combination of distance separation and antenna directivity. Thus, while the examples correctly demonstrate that attempts to reuse a frequency to the sam
17、e place at the same time will fail, this conclusion ignores the key factor of being able to manage HF spectrum effectively to allow both the multiple use of frequencies within a band or the reuse of single frequencies to different locations or at different times. 4 Rep. ITU-R M.2080 The frequency sp
18、ectrum is limited and the only way to accommodate additional requirements is to increase sharing arrangements between services. Annex 2 Spectrograms from monitoring campaigns To support the work in developing proposals for the WRC-07 on AI 1.13, monitoring stations in a part of Region 1 conducted mo
19、nitoring campaigns (2 per year, since 2004) to collect information on the actual use of the spectrum between 4-10 MHz. The results of the monitoring campaigns were analysed together by experts from participating monitoring stations and representatives from all services involved in the agenda item. T
20、he Annex presents per MHz a summary of this analysis. View I In conducting the monitoring campaigns, all issues were carefully considered to ensure that the maximum number of emissions could be detected taking into account equipment availability, timescale and area covered. Before the monitoring cam
21、paigns were started, a common set of parameters had to be defined to be applied to automatic measurements. Considering modern measuring equipment as well as equipment available at monitoring stations, experts found a sweep time of 10 s for a frequency range of 200 kHz was a good compromise. Although
22、 emissions with a shorter duration than 10 s may be partly missed, the probability of this was reduced by multiple stations monitoring the same range simultaneously. By monitoring identical frequency ranges at up to 4 locations, the impact of equipment failures was minimized and a much greater part
23、of the CEPT area could be covered. Although the monitoring campaigns were conducted in Region 1, propagation conditions allow emissions emanating from other Regions to be taken into account if they were received with a sufficient level at the participating monitoring stations. The database of manual
24、 observations confirms reception of emissions emanating from outside Region 1. The results of these monitoring campaigns should be combined with the results of equivalent campaigns conducted in Region 1 outside the European Conference of Postal and Telecommunications Administrations (CEPT) area, Reg
25、ion 2 and Region 3 if there are any, to provide knowledge of up-to-date frequency usage which can be used in any discussions on changes to Article 5 of the Radio Regulations. It does not seem feasible to monitor all emissions; notably adaptive short-time-emissions which are to be received at the noi
26、se floor, within a 6 MHz broad range (4-10 MHz). The number of missed emissions will be reduced by monitoring very small bands at a large number of monitoring stations using fast equipment. Comparison of the spectrograms with the data collected by manual monitoring confirms that short duration emiss
27、ions and signals just above the noise floor are shown. Administrations concerned about the possibility of missed emissions are invited to take part in monitoring campaigns and to contribute the results to provide an overview of frequency usage worldwide. Rep. ITU-R M.2080 5 View II The monitoring ca
28、mpaign overlooked many issues that cause it to underestimate the number of fixed and mobile transmissions. It is specific to only one region and does not consider the impact to other regions for the sharing situations that are identified. By utilizing a 200 kHz bandwidth and 10 s cut-off for transmi
29、ssions, as well as the schedule to divide the bands monitored between groups of 3 to 4 monitoring stations, it is very likely that a majority of fixed and mobile transmissions were missed. Most adaptive systems in use today pass data instead of voice and most transmissions are very short to a specif
30、ic location. There are usually multiple transmissions per hour but each of these individual transmissions would be lost in the large bandwidth and transmission time cut-off. In addition the received adaptive system signal is at the noise floor at the receive site given the need to maintain large net
31、 communications. These transmissions, including voice, would have been missed by this monitoring campaign. Annex 3 Sharing analysis of specific sharing conditions in the 4-10 MHz band Sharing situations between services is determined by receiver location and very rarely by transmitter location. HF t
32、ransmission footprints can be thousands of kilometres in width and length. Co-frequency sharing situations are likely when frequency bands are allocated to different services. For adaptive systems, increasing the number of frequencies in the user group pool allows for an increase in the user group s
33、ize but leaves less spectrum that is not in contention between user groups thus increasing congestion. View I Additional sharing between services is problematic. Adaptive systems can also experience difficulties sharing. As a result of propagation, harmful co-frequency and co-coverage interference w
34、ould be a consequence if the Radio Regulations provided additional sharing. View II The allocation of bands for shared use by the fixed, mobile and broadcasting services is considered to offer all the services access to spectrum in a compatible manner, noting that: the band 3 950-4 000 kHz (R1 and R
35、3) is allocated to the fixed and broadcasting service without there being any specific sharing criteria; there are already examples of geographical managed coexistence between the fixed and broadcasting service, e.g. coexistence between the fixed and mobile services and the broadcasting service, ope
36、rating in accordance with RR No. 4.113, in the bands 4 850-4 995 kHz, 4 995-5 005 kHz and 5 060-5 250 kHz is long established and generally succeeds because of the predominance of near vertical incidence skywave (NVIS) techniques for the broadcasting service which, for transmissions to or from the s
37、ame general location/area, naturally operate at lower frequencies than for longer distance oblique incidence skywave paths in the fixed and mobile services; there are already examples of time managed sharing between the maritime mobile service and the broadcasting service which, as both services ope
38、rate on a time scheduled basis with a good degree of regularity, could be further developed; 6 Rep. ITU-R M.2080 frequency agile fixed and mobile links can be designed to avoid collisions with scheduled broadcasting transmissions; there are already examples of geographical managed coexistence betwee
39、n the fixed and broadcasting service. Annex 4 HF compatibility considerations Review of the Joint Interim Working Party (JIWP) Report for WARC-92, supported by later developments and studies on HF systems, particularly as regards techniques for improving spectrum efficiency, demonstrates that severa
40、l types of sharing scenarios including possibilities for broadcasting sharing directly with other services are feasible. The convergence in modulation and control techniques lead to similar operating characteristics. Once the circuit planning considerations, operational functions and characteristics
41、 have become so close as to be indistinguishable, the applications involved could coexist since their compatibility criteria will naturally be much the same. View I The allocation of bands for generic shared use by the fixed and mobile services is considered to offer a compatible and more efficient
42、use of the HF bands, noting that: several frequency bands between 4 and 30 MHz are already allocated on a shared basis to various radio services including the fixed and mobile services and, after 29 March 2009, the majority of bands between 4 and 10 MHz will have multiple uses, and that adaptive sys
43、tems require access to as wide a range of spectrum as possible for optimum operation (see considering a) of Resolution 729 (WRC-97); distinctions between the fixed and mobile services have become less obvious as new applications and technologies are developed and deployed. Sharing or coexistence for
44、 fixed and mobile applications can be accomplished in real time by using: a combination of automated channel conflict avoidance techniques, as required by resolves 2 and 3 of Resolution 729 (WRC-97); a compatible digital modulation scheme with adaptable channel bandwidth and data traffic capabilitie
45、s; and natural time sharing possibilities of the differing patterns of use of the various services and the relatively short transmission times of the packet based protocols of the new digital data exchange systems. The increasing convergence between the operational characteristics of modern data exc
46、hange systems developed for fixed and mobile use in the HF bands is further demonstrated by the fact that most of these new systems now employ orthogonal frequency division multiplexing (OFDM) as a common transmission standard. There is even convergence with HF broadcasting, since the Digital Radio
47、Mondiale (DRM) system, developed to replace analogue modulation for MF/HF sound broadcasting, operates within an OFDM envelope. A characteristic of OFDM based systems is that it is possible to tailor the transmission coding characteristics to give the best match to the service requirements and radio
48、 propagation factors at the time of transmission. Rep. ITU-R M.2080 7 The convergence in modulation and control techniques for modern fixed and mobile applications means that their operations will increasingly take place within a similar envelope of characteristics, including the spectrum mask. Once
49、 the circuit planning considerations, operational functions and characteristics have become so close as to be indistinguishable, the applications involved could coexist since their compatibility criteria will naturally be much the same. View II The basis of this Annex is information contained in CCIR JIWP 10-6-8-9/1 formed prior to WARC-92. The information in that document only addresses regulatory issues and does not address the actual technical feasibility of additional sharing in the 4-10 MHz band. At the time that document was written HF usage for the fix
