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APPROVED FOR RELEASE: 2007/42/09: CIA-RDP82-04850R000500044414-7 FOR OFFICIAL USE ONLY - JPRS L/ 10368 4 March 1982 W~rldwi~~ Re ort _ p TEIECOMMUNICATIONS POLICY, . RESEARCH At~D DEYELOPMENT CFO~10 4/82) Fg~~ FOREIGN BROADCAST INFOF~MATION SERViCE FOR OFFICIAL USE ONLY APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 NOTE ' JPRS publications contain infor;nation primarily from foreign - newspapers, periodicals and books, but also from news agency transmissions and broadcasts. Materials from foreign-language sources are translated; those from English-language sources _ are transcribed or reprinted, with the original phrasing and other characteristics retained. Headlines, editorial reports, and material enclosed in brackets . arz supplied by JPRS. Processing indicators such as [Text] or [Excerpt] in the first line of each item, ar following the last line of a brief, indicate how the original information was processed. Where no processing indicator is given, the infor- mation was summarized or extracted. Unfamiliar names rendered phonetically or transl~terated are enclosed in parentheses. Words or names preceded by a ques- tion mark and enclosed in parentheses were not clear in the original but have been supplied as appropriate in context. Other unattributed parenthetical notes with in the body of an item originate with the source. Times within items are as ' given by source. , The contents of this publication in no way represent the poli- cies, views or attitudes of the U.S. Government. , . COPYRIGHT LAWS AND REGULATIONS GOVERNING OWNERSHIP OF MATERIALS REPRODUCED HEREIN REQUIRE' TNAT DISSEMINATION OF THIS PUBLICATION BE RESTRICTED FOR OFFICIAL USE ONLY. APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 FOR OFFICIAL USE ONZY - JPRS L/10368 4 March 198 2 WORLDWID~ REPORT TELECOI~IMUNICATIONS POLIC~I, RESEARCH AND DEVELOPMENT (FOUO 4/321 CONTENTS ~AS IA JAP AN B riefs NTT Policy on Satellites. l. _ SUB-SAHARAN AFRTCA INTE R-AF12I CAN AFFAI RS APTU Favors AFSAT Satellite for 1985-1994 (Pierre Langereux; AIR ET COSMOS, 16 Jan 82) . . . . . . . . . . . . . . . . . . . 2 ZAI RE B rie fs Agreement With Burundi 7 ZIMBABWE Briefs ~ooperation With Romanian Newa Agency 8 _ a _ [III - WW - 140 FOUO] FOR OFFICIwL USE ONLY APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 FOR OFF[CIAL USE ONLY ~ WES T EUItOx E I TALY Microproceasor Applications :Ln Transmission Systems ' (M. Calabrese, et al.; EITT~.'RONTCA E TELECpMUNICAZZpNI~ Nov-Dec 81) . 9 Digital Radio-Relay Syatems at 19 Qiz in Urban Areas (P. Amadesi, et al.; ELFTTRONICA E~LEOOMt~TICA.ZIONI, Nov-Dec 81) 21 I � - b - FOR OFFICIAL USE ONLY APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 FOR OFFICIAL USE ONLY JAPAN BRIEFS IvTT POLICY ON SATELLITES--Tokyo, 16 Feb (JIJI Press)---The quasi-governmental Nippon Telegraph and T~lephone Public Cnrp. (NTT) has fixed its policy of _ orbiting its large-capacity commLnications satellites using the space shuttle of the U.S. National Aeronautics and Space Administration (NASA). Japan's communi- cations satellites for practical i:se have hitherto been launched using domesti- cally-produced rockets. NTT, the narion's telecommi.mications monopoly, will seek approval of the Space Development Council before making a final decision on this , score. Under NTT's plans revealed so far, it will blast off a one-ton communica- tions satellite with a capacity of 25,000 telephone circuits in fiscal 1988 and a four-ton satellite with a capacity of 100,G00 circuits around fiscal 1992. Japan's fiscal year starts in April. NTT also plans to link via these satellites telephone stations exclusively for long-distance calls to be set up in each - by putting up antennas of four meters in diameter on the roofs of these ~ta.tions. Another factor behind NTT's emerging policy of launching large- capacity cor;imunications satellites is its strong wish to advance into data communications business. [Text] [OW161451 Tokyo JIJI in English 1436 GMT 16 Feb 82] r,g0: 5500/2123 1 - FOR OFFICIAL USE ONLY APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 APPROVED FOR RELEASE: 2007102/09: CIA-RDP82-00850R000500040014-7 - EOR OFF[CIAL USE ONLY ZNTER AFRIGAN AFFAIRS ~ APTU FAVORS AFSAT ~ATELLITE FOR 1985-1994 Paris AIR ET COSMOS in French 16 Jan 82 pp 34-36 [Article by Pierre Langereux: "For a Regional Telecommunications Satellite in Af- rica--The Cauntries of the APTU (African Postal and Telecommunications Union) in Favor of an 'AFSAT' Satellite ror 1?85-1994"] [Text] The study carried out, under the aegis of the Euroapace group, by a Euro- pean consultant group com~rising Satel-Canseil, the ITM [Modern Industries and Techniquea] company and the Bureau Yves Aoussin= concerning "the teleco~nimications _and radio-television needs of the 13 Francophone member countries of the AP TU~ and 4 neighbo ring cotm tries2 capable of being fulfilled by a satellite during the period 1985-1994," has shown that a regional teleco~mmunications satellite could be effectively useful Co a good number of countries of the APTU. The situation of the 17 African countr.ies concerned by the study (as well as that of the other countries of Africa, for that matter) is characterized b,y two dominant traits: low GNP per inhabitant (Er 1,000 to 2,400), and disturbing u~1~~.erequipment. , According to Mamadou Simpore, secretary general of the APTL', '�ror more than SO mil- lion inhabitants (including Chad) of the APTU member ~.ountries, there were in 1980 only 110,000 direct-exchange telephone lines, or about 1 line per 500 popula.tion!" Moreover, this insufficiency reflects some striking inequalities. As regards the APTU, nearly 80 percent of telephone subscribers are in the capitals, wi~h the rest = distributed among a few large cities; but there are practical.l.y no teleconununica- tions facilities in the rural localities and even fewer in eh~ country- side. In addition, the existing lines are subject to a variable, but always high, rate of unavailability. The satellite may o~viously appear ambitiuus, even extravaganC, in such a context. Actually, it is not so at all, Mamadou Simpore states, for three principal reasons: the satellite is the only feasible means of transmission it~ Africa, it is less ex- pensive than the other transmission means, and it can only have a considerable ef- - fect on the underequipment situation of the African continent. 1. Beni.n, Central African Republic, Comores, Congo, Ivory Coast, Djibouti, tJpper Volka, Mali, Mauritania, Niger, Rwanda, Senegal and Togo. Chad, a member of i.he APTU, did not participate in the study. 2. Zaire, Ghuna, Kenya and Sierra Leone. - 2 FOR c~FFICIAL USE ONLY J APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 APPROVED FOR RELEASE: 2047/02/09: CIA-RDP82-00850R004500040014-7 FOR OFFICIAL USE ONLY Study of Needs The Eurospace study, carried out in close coordination with the APTU secretariat and the African national administrations in the AFSAT group, began with a broad study of the needs of the countries concerned and the development they have planned. Thus, the consultants evaluated the entirety of the telecomlr,unications and radio-television needs of each country, and then they estimated the preportion of service that could reasonably necessitate a satellite rather than conventional _ telecommunications means (radio waves, cables, etc). ~ The needs were divided into three categories: international and national (�nter- urban) public telecommunications, sudio and video broadcasting, and telecommunica- tions in the rural environment--these last being distinguished from interurban telecommunications for functional reasons. " The domestic situation of the countries was evsluated in terms of four equipment levels: good, poor, or nonexistent network connection, or no network (the most com- mon situation). The first two cases relate to national interurban connections, and _ the third and fourtk,, to rural connections. For international telecoaununications, the calculation of the traffic and the number - of international circuits took account of all the APTU member countries as we11 as Cameroon, Ganon and Zaire. The assumptions made are an average annual increase for the whole of the countries' internationalconnections, but varying with the period - considered (15 percent from 1979 to 1990 and 12.5 percent thereafter). Particular stimuli to:.ard modifications of routing, transmission and general operation were also envisioned. Finally, for distribution of traffic as between earth and space f"acilities, the study adopted the following criteria: routing of traffic to region- a? satellite on demand assignment, and 100-percent direct point--to-point connec- tions via satellite when the existing infrastructure is weak, or only 25-perrent by such connections when there is radio or underwater cables. For national telecommunications (not including rural), calculation of the circuit needs was based on a spatial-temporal estimate of the subscriber demand and on traffic Forecasts, and a proposal for a distribution between satellite and earth facilities resulted. All localities that have telephone service or rare to have it between now and 1985 were taken into consideration. For the period 1985-1994, ttiere c~as close coordination with the na'.ional administrations as regards the rates of growth considered in order to adapt th~�m to each country, sometime: with growth rate differentiated as between the capital and the provinces. The number of tele- phone circuits anticipated for needs other than telephony were estimated at an overall 5 percent of the number of channels expected for public service. These circuits will be for telegraphy, leased circuits, new services (telecopying, data- transmissi.on, etc) and for replacement af certain pri�~ate networks that l:ave now reached saturation. An estimate of traffic distribution was made in function of distances, with the ex- - isting facilities taken into account. When there ~re modern facilities (cables, radio) between two Iocalities, it: was supposed that 75 percent of tre circuits - would go by satellite beyond a distance of 500 km; 50 percent for distances of 100 _ to 500 km; and that below 100 km, there would be no cirr_uita via satellite. On i:he other nand, when there are no moder~n facilities, all circuits would go via satel- 3 FOR OFFICIAL USE Ol!'LY APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000540040014-7 FOR OFFICIAL USE ONLY L1CP_--1R all countries--beyond a dietance of 100 km. Another hypothesis grouped the countries into three categories for the distribution as between earth and space facilities, with a t-,~~avier weighting than before as regards the criteria other than economic. This leads in particular to a more precise assignment of the distribu- tions in terms of the distances. For telecommunications in the rural environment (defined as the regions not pres- ently served by the national telecommunications network), two types of installation ar~ envisioned: in a locality for public service, and providing service ko all the inrcabitants; or in the countryside, mainly for the benefit of the farmers. The in- stallation strategy is the planned to have two phases: first of all, installation of network access points consisting of a"rural communications office" equipped with a telex and telephone, and pcssibly a community TVi center; and next, extension of service to subscribers who might ~ncrease the pr~fitability of the system, with more r.ur.i offices added, creation of small local r.ietworks, and installation of networks in the countryside. The total operatia:~ (the two phases) would be aver a , period of 5 to 7 years. The forecasting or rural telephone traffic was done by two methods. The basic hy- pothesis considers maximum geographical service ac the lowest cost, the objective for 1994 being the serving of 1 percent of the rural population residing in the lo- calities concerned, with doubling of use uver a 10-year period (1985-1994). Com- plementarily, a survey was made of the needs for the entirety of the rur21 zones of each APTU country as of 1994. Total APTU Half-L~uplex and Via-Satellite Circuit Needs Telephone 1985 1994 Half-Duplex V~a Via Circuits Total Satellite Total Satellite Internationa?. 600 400 1,300 1,000 Interurban* 9,600 4,200 19,999 8,400 Rural 5,200 1,900 31,000 11,000 Totals 15,400 6,500 51,300 20,400 a Radio-Television 2 to II TV programs 10 to 20 FM-radio programs Special service channels *[Sourc~~ gives no note relating to this note reference.] - It is proposed to meet the rura~ telecommunications and television needs nanly by satellite, ex~ept in ~he smgll-size countries. This would lead, as from 1985, to a cot?ununity tele~ommunications and TV service, in the proximity of a station installed i~-~ each locality, and in 1994, to a distribution of the preceding service to the other subscribers of the locality (by wire) and to those located outside (by radio- telephone). For audio and video broadcasting, the esti*.:~tion is more difEicult to make. The countries were divided into two categories. Those that havF already chosen to transmit radio-TV progran~s via satellite--by means of a leF.sed reFeater on an In- 4 = FOR OFFICIAL USIE ONLX APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 - FOR OFFICIAL USE ONLY telsat satellite--are obviously in a very good position for extension of coverage by way of an African regional satellite. For the large countries that do not ~res- ently have a sizable radio-beam infrastructure, the satellite represents the most effective means (in terms of cost and speed of service) for providing coverage of the country. But ~his assumes a complementary equipment effo~t (earth transmitting staticn, receiving stations, TV-FM transmitters, community receivers, etc) in order to make the space investinent a profitable one. For the countries that already have a radio-beam network that is dense or developing, the satellite obviously seems less attractive. As for other countries of small territory, use of the satellite does not seem justified. Conclusions in Favor of the Satellite The study thus concludes that for the 13 countries of the APTU, the interurban half-duplex-circuit needscome to 9,600 in 1985 and 19,000 in 1994--a 7-percent rate of growth. If Zaire is added, these figures are 11,600 and 23,000 half-duplex circuits, respectively. The eventual use of a regional satellite for the international traffic among the 17 countries studies (the 13 APTU countries and the 4 neighboring ones) corresponds to a capacity of 400 half-duplex circuits in 1985 and 988 in 1994. As regards nation- al (interurban) traffic, the initial estimates indicate about 4,200 half-duplex circuits in 1985 and 5,900 in 1994, including Zaire. In the case of hypotheses that further favor the ground-based systems, the tatal number of half-duplex cir- - cuits still comes to 2,700. Concerning rural telecommunications, the total half-duplex-circuit needs of the 13 countries of the APTU was estimated at 5,~00 in 1985 and 31,000 in 1994. Including Zaire, these figures are 6,300 and 49,200 half-duplex circuits, respectively. rltiiong these needs, the proportion of rural telecommunications that could go vi.a satellite was estimated at 1,900 nalf-duplex circuits in 1985 and 11,000 in 1994, which represents an average annual rate of growth of 19 percent. With ~aire, these - needs reach 2,500 and 15,700 half-duplex circuits, respectively. This 19-percent growth rate, which may seem high in comparison with the other categories of tele- communications, actually follows from the tremendous rural-telecommunications lag in Africa. The secretary general of the APTU recognizes, in fact, that a start has to be made from nothirig in order to try to reach an "acceptable" situation around - 1994--one which would still be only a 1-percent telephone density in certain local- ities and even just 0.5 percent in others! In the area of radio-television, where extreme infrastructural weakness is also noted, the equipment effort to be made is consideraole. But it is presently imped- ed by the lack of equipment, qualified personnel and financial means. The APTU study concludes that "six countries of Africa--the Cpntral African Republic, Upper Volta, rfauritania, Mali, Niger and Senegal--present very favorable characteristics for use of the satellite for meeting their radio-TV needs, and that two other coun- tries--Congo and Ivory Coast--despite the present or future large size of their radio-beam network, could find use of a satellite an attractive alternative for de- velopment of their TV-FM radio network." On the other hand, the APTU study rP- cognizes that the other five countries--Benin, Comores, Djibouti, Rwanda and Togo-- could solve their radio-TV network problems without ~ecourse to the satellite. 5 FOR OFFICIAL USE ONLY APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 APPROVED FOR RELEASE: 2047/02/09: CIA-RDP82-00850R004500040014-7 FOR OFFICIAL USE ONLY , Such are the results of the study approved by the Council of the APTU at Lome in August 1981 and presented publicly for the first time at the recent Eurospace In- ternational Conference by Mamadou Simpore, secretary general of the APTU. These data now constitute the basis for new complementary studies recently ordered from Eurospace, both by the APTU and by the Pan-African Telecommunications +.inion (PATU), in liaison with the African National Radio-Television Union (URTNA). One of the studies, for which a contract of Fr 2 million has been made, is an extension to the scale of the PATU--which incorporates all the countries of Africa (including those of the APTU)--of the telecommunicatiuns-needs study previously carried out by Eurospace. The other is a parametric study concerning the feasibility of an AFSAT satellite system covering the needs of the APTU and eventaully those of the PATU also. This second study is presently financed ~o the extent of Fr 3 million by the European Development Fund (EDF), but supplementary financing is expected from France, Italy and Great Britain, to reach the Fr Fi million needed for carrying out the ' work. These new studies will be conducted under the direction of the European Eurospace group, with the participation of the European Space Agency (ESA), the ITM company and the Fr~nch National Center for Telecommunications Studies (CNET), as - well as with the GTS (Great Britain) and Consultel (Italy) companies. COPYRIGHT: A. & C. 1982 _ 11267 CSO: 5500/5665 6 - FOR OFFICIAL USE ONII.Y APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 APPROVED FOR RELEASE: 2007142/09: CIA-RDP82-40854R040500040014-7 FOR OEFICIAL USE ONLY ZAIRE _ BRIEFS AGREEMENT WITH BURUNDI--Zaire/Burundi agreement on telecommunications. The govern- = ment of the Republic of Burundi and the Executive Council of the Republic of Zaire signed a formzl agreement on telecommunications at Bujumbura on 11 December. The purpose of the agreement is to set up and operate a direct telecommunications link between the two countries for tele~raphic services, telex, rented circuits, fac- simile, data transmission and radiophototelegrams using available and future tech- - nology. [Text] [Paris MARCHES TRQPICAUX ET MEDITERRANEENS in French No 1886, = 1 Jan 82 p 39] jCOPYRIGHT: Rene Moreux et Cie Paris 1982J 9855 CSO: 5500/5658 ~ ~ 7 FOI~ OFF[CIAL USE ONLY APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500044414-7 FOR OFFICI~L l1SE ONL1' ZIMBABWE , RRIEFS COOPERATION WITH ROMt~NIAN NEWS AGENCY--Salisbury, 25 Feb (PL)--Representatives from the News Agencies of Zimbabwe (ZIANA) and Romanian (AGERPR~SS) signed in - this capital an agreement for the exchange of information. The agreement was signed by the chairman of the amalgamated mass media of Zimbabwe Davison Sadza and the Romanian ambassador to this country Petre Bla~ovici. Sadza said he hoped the signing of the agreement would go a iong way to improve the Yelationship between the two countries. In reply Ambassador Blajovlr_i said the signing was a new step forward to improve cooperation between the two countries. [TextJ [PA242130 Havana PRELA in English 2020 GMT 24 Feb 82] CSO: SS00/5693 ~ g - FOR OFFICIAL USE 4NLY APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500044014-7 FOIt OFFICIAL USE ONLY ITALY MICROPRUCESSOR APPLICATIUNS IN TRANSMISSION SYSTEMS Turin ELETTRONICA E TELECOMUNICAZIONI ir. Italian Nov-Dec 81 np 241-246 - [Article by M. Calabrese, M. De Bortoli, G. Panarotto, G. Rocca and E. Thomas*] - [Text] Summary--Microprocessor applications in transmission systems. This paper illustrates the reasons in favor of the use of microprocessors in telecommunica- tions transmission systems. After an overview of the possible fields of applica- tion of these devices, together with the advantages and the cc~mpromises for a pro- fitable insertion within the complete system, some applications in experimental plants are described. In a modem for digital transmission at 140 Mbit/s rate, the - microprocessor controls several fundamental parameters; in another application it _ implements a new equalization algorithm and in a field trial (COS 3/FOSTER) it col- lects the significant link parameters and processes them for the overall system be- havior monitoring. A forecast is also presented on futu-e developments of these applications. 1. Introduction _ Many applications have been found for microprocessors in the telecommunications field, especially wittiin the framework of switching installations. Their introduction into transmission systems has been less immediate, though, main- ly for two reasons: the analog nature of the signal to be treated, and the high frequencies involved. The digital transmission systems offer greater possibilities for insertion of mi- croprocessor devices, since treatment of the signal is required at discrete in stants--that is, the instants at which the decision is made. * Dr of Engineering Mario Calabreses, p.i. [expansion unknown] Marco De Bortoli, - Dr of Engineering Gianfranco Panarotto, p.i. Giovanni Rocca, p.i. Ernesto Thomas, of the CSELT (Telecommunications Research ~nd Study Center), Turin. ~ Typescript received 23 July 1981. This paper ~;as presented to the annual Congress of the AICA [Italian Association for Automatic Calculation] at Pavia, 23-25 September 1981. 9 FOR OFFICIAL USE ONLY APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00854R000540040014-7 FOR OFFICIAL USE ONLY [Jithin this framework., two types of application have been individuated, distin- guished essentially by the different ratio between the processing speed of the mi- cro;~rocessor used and the speed of transmission of the symbols: 1) processing of the signal in real time, for transmission systems of sufficiently low ,speed; 2) management of the equipment through processing of statistical magnitudes and of significant signals at low speed, both through control of algorithms and through monitoring of the system's performance characteristics. These two aspects are dicussed in detail in this paper. Several sets of equipment built in the CSELT are described. For each of them, the purpose and the type of processing done cn the signals are presented. From the applications described, the advantages that can be obtained through this type of approach are obvious, especially for experimental projects: for example, the considerable flexibility in the various tests, because of the possibility of doing things through mere changes o� the software. 2. Genera: Considerations on the Use of Microprocessors in Transmission Equipment = The use of microprocessors in transmission equipment, in place of analog circuits or the traditional logical circuits, is justified when one of the f~llowing condi- - tions occurs: a) real-time processing of the signal is very complex and must be done with a low- - speed data flow. In this case, use of a microprocessor considerably simplifies the hardware of the equipment, requiring from the software a part of the funct~~ions that have to be carried out; b) the problem arises of monitoring functional blocks of the transmission equip- ment, through development of algorithms on low-speed signals. or of keeping the performance charact~ristics of such ~.pparatuses under contr~l. In such case, in addition to the advantages cited in paragraph a), use of the microprocessor gives the control or management structure considerable flexibility, tliis being an especi- ally useful characteristic when experimental equipment is developed. Attention is now drawn to the two peculiar characteristics of microprocessor archi- tecture: modularity of the hardware and flexibility of the software. Current technology makes available a considerable number of components, capable of carrying out complex and specialized opErations,that can be inserted into micro- processor systems as peripheral equipment un the system buses. Several components of special importauce in transmission systems can be taken as examples. Analog-digital (A/D) and di$ital-analog (D/A) converters, which make it possible to digitalize analog signals and restore the processing results iii analog - form, are the necessary i.nterfaces between the microprocessor and the system. In addition, if the processings are rather complex from the mathematical F~oint of view, it is possible to insert into the system a multiplier or arithmetical pro- _ cessing unit capable of carrying out the fundamental arithmetica..l operations auto- nomously, even on numbers ex~,rCssed in floating point, and of doing the conversions between that format and the entire format. ~.0 FOR OFFICIAL USE ONLY APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500044014-7 - FOR OFFICIAL USE ONLY A single well-organized system is therefore ~asily e~pandable, from the hardware point of view, to meet the individual requirements and adapt the structure to new situations that may arise from time to time it~ the experimentation. As for the software, its task is to receive the signals and process them. Through program changes, it is possible t~ modify the al~orithms, while by modifying the data it is possible to vary the static parameters of the problem, thus adapting the program to the specific application in the best way. In cases in which the processing of the signal has to be especially fast, it is ad- - visable to use bipolar microprocessors of the bit-slice ~ype instead of the more usual microprocessors built with MOS [Metal-Oxide Semiconductor] terhnologies. This choice has an effect on both the hardware and the software. The user does in fact have to construct both the central unit on the basis of the individual compo- nents and the set of instructions most appropriate for the application or. the basis of the elementary operations of logical-arithmetic type defined within the individ- - ual components (microinstructions). The set of instructions is defined by the us- _ er by accurate analysis of the slgorithm to be developed and isolation of the most elementary and repetitive steps. This approach may prove considerably burdensom in cases where support instruments are lacking, both for development of the software and for the checking-out of the system; nevertheless, the advantages obtained in terms of processing speed are notable. 2.1. Processing of the Signal Some af the main considerations relating to transmission of the signals are digital filtering, ad.aptive equalization, the algorithms for extraction of the synchron- isms, estimation of channels not known beforehand, and coding and decoding opera- tions. These functions, usually carried ouL in analog mode or with dedicated logic, are carried out by means of logical and mathematical operations done on the flow of the signal samples taken at the symbol-transmission speed. One therefore thinks immediately of the possibility of doing these operations with microprocessors. There is, however, a limitation i.n their use for these purposes, due essentisily to the reduced processing speed as compared with the transcnission _ speeds usually used. The basic cause of this limitation lies in the complexity of the a.lgorithms and in the mass of data to be treated, which necessitate use o� mi- croprocessors for processing signals whose transmission speed does not exceed some 10 kHz. In order to partly overcome that limit, it is possible to construct microprocessor architectures in which each processor is dedicated to the carrying-out of a single function, with considerable advantages in overall processing speed and therefore with the possibility of applica~ion to systems of higher transmission speed. In Chapter 4, there is described in detail, as an examrle of real-time precessing of the signal, a nonlinear equalizer of the "Decision Feedback and Eeedforward" type (Bibliography 2). 11 ' FOR OFFICIAL USE ONLY APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 FOR OFFICIAL USE ONLY The high number of processings to be done, which is connected with the necessity of _ a certain speed of the data-flow to be treated, required the use of a microprocess- of the bit-slice type. It is interesting to note that this arrangement fu1J.y met the expectations as re- gai�ds the flexibility of its use: it was in ract possible, solely with m~difica- tions of the software, to test the algorithm ir. various condition$ of number of cells and parameter values. It was also possible--aQain, solely with variations of ~ the software--to achieve a transverse linesr eQUalizer for the purpoe~ of comparine the performance characteristics of the two eQUalizers. - 2.2. Management and Con*.rol of the Systems A different class of microprocessor applications is the processin� of the statisti- _ cal parameter's connected with the information signal. Examples of these statisti- cal magnitudes, which werE used in the systems illustrated later, are the mean quadratic error and the average of the absolute values of the error encountered in the decision-making organ. By optimizin~ ~these magnitudes,.it is possible to control several parameters of fundamental importance in the system, such as the coefficients of the adaptive equalizer, the optimal ptiase for signal-sampling, the phase of the demodulator--for e:cample, in AM-SSB (Amplitude Modulation - Single Side-Ban) systems that require coherent demodulation. _ The statistical magnitudes referred to above can be obtained with dedicater: cir- cuits or by making use of the microprocessor's processing capacities. In the former case, the magnitudes are calculated by the external circuitsusing the in-line signals and are transferred to the microprocessor at lower speed. In the latter case, they are generally determined by using a data flow obtained by sub- - samplin~ of the in-line signal. The experimentation done den~onstrates that statistical magnitudes calculated in this way are equally significant for controlling the system's parameters, provided that the time interval of their integration is suitably chosen. In both cases indicated above, the microprocessor is asked to perform the task of minimizing the statistical function, in accordance with the optimization algorithms best~adapted to the situation in question, of establishing the values of the para- meters under control, and as the case may require, of f~zrnishing indications of correct system functioning to a local operator. In Ch3pter 3 is presented a transmission system, at the rate of 140 Mbit/s, that uses the microprocessor for management of the receiving terminal. The microproces- sor is used for control of the process of adaptation of the coefficients of the transverse equalizer that has to compensate for the cable distortions, for control- ling the decision thresholds and for recovery of the optimal sampling instant. - Use of the microprocessor has proved especially a~'~rantageous because it has given the designers considerable experience on the validity and the limits o� all the al- ternatives examined, testing them directly in the installations in real conditions and not only by computer simulation of th~~m. 12 . FOR OFFICIAL USE ON~.Y APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-04850R000500040014-7 FOR OFFICIAL L'5E ONLY A final field of use of this type af device is general monitoring of the correct functioning of the system and of its performance characteristics. For such pur- - poses, the microprocessor does not have to have special speed characteristics but only suitable peripheral equipment capable of collecting the magnitudes to be ex- amined and providing them to the user in the m~st appropriate forn~, and, as the case may call for, transmitting them to collection and supervision centers, as in the remote monitoring systems, for example. Microprocessors offer the advantage of being able ta coordinate collection of the most significant data on the proper functioning of the ~ystem and do the process~ ing of them, thus furnishing a complete and organic picture of the parameters to be monitored and facilitating recognition of causes of malfunction. This methodology is especially useful in the perfecting of experimental systems and in character.ization of them. In Chapter 5 is presented, as an example of this approach, the system for acquisi- - tion and processing of the measurement data of the ez;perimental optical-fiber transmission installation COS 3/FOSTER. In this system, which has the task of re- ~ lating deterioration of transmission quality to the performance characteristics of components of fundamental importance, it has been possible to distribute the pro- cessi:ig capacity to the individual terminals that are geographically dispersed, thus decentralizing the monitoring and treatment of the magnitudes measured and re- serving to the centralized control unit the job of gathering and correlating the data. 3. Microprocessor Inserted into the Hybrid-Type 140 Mbit/s Digital Transmission System 3.1. Objectives of the Application The microprocessor application concerns adaptive control of the multilevel receiv- ing tenninal of th:~ "hybrid"-type 140 Mbit/s digital transmission system developed in the CSELT (Bibliography 1). This system provides �or the insertion, between two digital regener.ators, of a num- ber of analog repeaters that only malce it possibl~ to recover the attenuation in- ~roduced by the cable into the useful signal band ~Figure 1): the effects of dis- equalization of the signal and of the related variat~~:~ accumulate along the n sections of analog repeti.tion fallinQ between two digital terminals. It is therefore necessary to provide, for a high number of sections, an adaptive- control device that makes it possible to re~over the variations of the system's characteristics in time, maintaining satisfactory and constant transmission qual- ity. For this purose, the microprocessor device inserted into the receiving terminal (Figure 2) examines the signal received, taking a sample out of every 1,000, and calculates an error function (EF)*, by minimizing which it controls: * The EF is defined thus: N iE~~li - iri~~ in which li is the level of the sym- - bol received, lri is the relative reference level, and N is the base o� integra- tion of the error function. 13 FOR OFFICIAL USF ONLY APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 FOR OFFICIAL USE ONLY 1) the phase of sampling ins~ant ~T; - 2) the values o~ the decision thresholds; 3) the coefficients of the adaptive transverse equalizer (ETA). (1) ~1) RI/ETITOHE NtNNERICO RIPETITORE NUMERICO i p R.iT. p - - p n.ITr p RIPE'fITONI ANAIOCICI ~2~ l _ J eeaz ~ ~ 3~ SE210NE DI RIGENERAZIONE NUMERICA Figure 1. Block diagram of the hybrid transmission system Key: 1. Digital repeater 2. Analog repeaters 3. Digiral regeneration section / \ (2) (3) (4) (S) (6~ (7 \ 1 / EQUALIZ� F1U350 FILTHO FLUSSO p' + SOIMMA ZqTORE ~~~0� DEC~- OATI OATI q~CEZ10NE - TORE TRASVER NATORE SOAE DECISO DALLA SALE IINEA ~8~ COEfF. CAMPIO� E.T.A. B NATONE ANELLO AD ~ ~ AGGANCIO ~ 1 O ~ ~S~~TIVO A DI FASE MICROVFOC. ~ SEGNALE SOTTOCAMV. ~12) , ~11) SFASATOHE f1/t7 VAHIA9ILE 1I1000 ~ FREOUENZA DI CAMPIONAMENTO SOGLIE 01 OECISIONE (13) Figure 2. Block diagram of the receiving terminal of the 140 Mbit/s system Key: 1. Data flow from line 8. ETA coefficient 2. Reception filter 9. Phase-hookup ring 3. Adder 10. Microprocessor 4. Transverse equalizer 11. Signal subsampled 5. Sampler 12. Variable phase-shifter 6. Decider 13. Sampling frequency 7. Data flow decided on 14. Decision thresholds = 3.2. Reascns for Adoption of a Microprocessor The device for control of the receiving terminal must carry out logical and arith- metic functions of a certain magnitude, in accordance with algorithms that are computer-simulated, only on the basis of simplified and therefore limiting wor;cing hypotheses. 14 FOR OFFICLAb USE ONLY APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 APPROVED FOR RELEASE: 2047102109: CIA-RDP82-00850R400504040014-7 FOR OFFICIAL flJ3E ON!.Y In the development phase, it is therefore indispensable to be able to make use of a device ir,~serted into the real terminal and making it possible to modify easily boll~ the test algorithms and the parameters relative to them. - A device built with a microprocessor meets these requirements, inasmuch as the hardwarestructure remains unchanged, while the behavior of the device depends on the ccntent of the program memories (algorithms) and data (parameters). In addi- tion, the various buses (addresses, data, control) existing in the microprocessing structure permit easy connection of the most diverse peripheral equipment, which makes possible rapid execution of ineasurements, recording, processing and presenta- tion of the data of preeminent interest. With the algorithms and the relative parameters defined, a aimpiified device is in- _ serted ~n the terminal; this device too is built with a microprocessor, both for easy transposition of the original device and because the complexity of the cir- cui~, dimensions, construction time, power consumption and costs are decidedly com- petitive with those of the alternative analog device built with traditional-logic circuits. 4. Microprocessor for Development of a Nonlinear Equaliz~r The application consists in the construction, by means of a microprocessor, ~f a type of nonlinear equalizer recentiy designed in the CSELT (Bibliography 2). This type of equalizer* unites with the principle of backward reaction of the deci- - sions decided on (decision feedback) the forward reaction of the same symbols (de- cision feedforward), thus permitting nearly total cancellation of the interfering signals, even in the presence of strongly distorted channels. _ The equalizer can be inserted into the receiving terminal of a digital transmission system in accordance with the block diagram of Figure 3. (1) (2) (3) (4) (S) (6) SEGNALE FILTRODI CAMVIO� fILTRONON DECISORE SIMBOL DALLA RICE210NE NATORE LINEARE OECISI LINEA ~ ] ~ FRE~UENZA DI CAMPIONAMENTO ~ Figure 3. Block diagram of receiving terminal of a digital transmission system with insertion of a nonlinear filter Key: 1. Signal from line 5. Decider 2. Reception filter 6. Symbols decided on 3. Sampler 7. Sampling frequency , 4. Nonlinear filter ~ * Patents filed. 15 FOR OFFIC[AL USE ONLY APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 APPROVED FOR RELEASE: 2007142/09: CIA-RDP82-40854R040500040014-7 FJR OFFICiAL USE ONLY The equalizer considered, the block diagram of which is given in Figure 4, presents two parallel paths: the upper one has the purpose of correcting the precursor of the input wave form, and the lower ane, the relative tails. h ~ , Kp Kp KO D + p + + p B ~ 4 f Kp� - SF~ T T - T + O A ~ ~ - + + T i D ~ - ~ - H'~ 0 w i ~ SFZ ~ 4 T T T~ ~l 0 C Kp� KO OM~ " Figure 4. Block diagram of the nonlinear equalizer YT JT 6T -T 0 T 4T t �T 0 T t �T 0+T t -T 0~T t A 8 C O ~ Figure 5. Diagram of the wave forms sampled at the various points of the equalizer The SF1 filter is a transverse filter with eight coefficients; it makes it possible to force to zero the interfering signals that are different from the precursor, which will be cancelled by the following cells with decision feedforward, and by the first tail. - The addition of an ever greater number of cells of the decision-feedforward type in cascade ensures a gradually decreasing error probability at the output of the upper branch, since, in the event of a-nistaken decision in a cell, the error can be rem- - edied in the succeeding cells. At the output of the upper path (point B), the sig- nal is affected by the residue of the first tail not completely cancelled by SF1. The SF2 filter too is a tY�ansverse filter with eight coefficients and has a role analogous to that of SF1; the residual tail is cancelled by a cell of the decision- feedback type, and the signal at point C will therefore be affected by a distortion due to the residue of the precursor. _ 16 FOR OFFICIAL USE ONLY APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 APPROVED FOR RELEASE: 2007/02/49: CIA-RDP82-00850R440500040014-7 FOR OFFICIAL USE ONLY The signals coming from the two routes flow together into an adder and from there into a double cell with feedforward and feedback reactions that provides sor elim- ination of the precursor signal and the residues tail. The diagrams of the wave farms sampled at poit~ts A, B, C and D are given in Fig- ure 5. The type of algorithm used and the type of signal worked on lend themselves very well to an arrangement using a microprocessor in which, by exploiting the flexibil- ity of the software prepared, it has been possible to develop the various internal functions of the equalizer and investigate various co~struction schemes and their relative performance characteristics. In particular, it has been possible to make a comp3rison between the performance characteristics of the nonlinear equalizer of Figure 4(with N= 3) and those of the eight-coefficient transverse equalizer of "zero-forcing" type--that is, of com- plexity equal to that of each of the twa shaping filters SF1 and SF2. From the curves of Figure 6, which indicate how the error rate at the decision point varies with the variance of the signal-to-noise (S/N) ratio at the input of the equalizing structure, it can be noted that the performance characteristics are better in the case of the nonlinear equalizer. 1: FILTRO NON LINEAR[ ~~2 2: fIITROTRALVERSAIE (3) Q , a s ~~3 Q W ~ ~ ~O~ ~ f 106 SM 14 16 18 17 1B 19 20 (dB) 6897 Figure 6. Curves comparing the performance characteristics of the nonlinear equal- izer and the transverse equalizer Key: 1. Nonlinear filter 2. Transverse filter 3. Error rate 5. Microprocessor Inserted into a System for Acquisition and Processing of the Measurement Data of the Experimental COS 3/FOSTER Installation The application consists in the construction of a microprocessor device whose task is to: 1) take the measurement data relative to the significant magnitudes of one or more transmission systems (up to a maximum of eight); 2) do several processing operations on them; , 17 FOR OFFICIAL USE ONLY APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 FOR OFF~C[AL USE ONLY 3) ti~ansrnit to a(remote) centralized organ the i:~formati~n put into memory; 4) present this intormation in viaual form for local monitoring. _ ~----~-----,r-----------,~-----r--- ~ I T. R~ T. R. T. R� T~ T� ~ I I ~ I SISTEMA U1 THA$1.115SK1NE I I I I I ~sros~rwo I~ ri~siTrvo ~ ~ I I isvos~nv I I ~srosrtrv ~ _ ( 1 4 YICRO~ I I A MICRO~ I I SU FIBHO OnIG ( 2) I ~ A MICRO~ I I A MICRO~ I7 ` vROCESS. ~I PROC ~ ~I PROCESS. II PROCESS Ii ~ ~ BUS RSm ~I I~ ~i II I li ~ IMODEM AqOEM I~ MOOE MOOEM ~ - --~I --~L-- CENTN~ CEMRALE ~ I CEN:~~LE CENTN. S. MARIA AVENTINO idpDEM MOOEM I EVR r 6~ flpAA~ r 7 1 IN VIA ~ ? SU~ ? / ~IHEA DEDICATA I ~ 3~ ~ 5~ I MOOEM "EM I ~ ISPOSITIV ~ I A MI~qO I ~ PRCCESS. ~ i~l II INTEAFA~CE ~ ~ FS zi7 ~ i ORGANODI ~ ELA80RAZIONE ~ I ~ ~ CEN7RAl122AT0 I ENTRALECOLOMBO ~ ~ 1IIk---------~ Figure 7. Block diagram of the measurement-data acquisition and processing system of the COS 3/FOSTER experimental installation Key: 1. Microprocessar device 5. EUR center 2. Optical-fiber transmission system 7. Rome-South center 3. Santa Maria in Via center 8. 5 RS-232 interfaces _ 4. Avention center 9. Centralized processing organ 5. Dedicated line 10. Colombo center , The device in question is inserted into a measurement-data acquisition and proces~- ing system, the block diagram of which is given in Figure 7 and that has the pur- pose of monitoring the performance characteristics of the COS 3/FOSTER experimental digital-transmission systems installed on optical cable between the Sax~ata Maria in Via and Rome-South exchanges, in Rome (Bibliography 3, 4, S). Because of the experimental aspect of the installation, it is necessary to relate the deterioration of transmission quality to the course of the per�ormance charac- teristics of thE principal system components to be monitored. It is therefore necessary for the microprocessor to take, at regular time inter- vals, a certain number of digital and analog magnitudes that characterize the sys- tems' transmission and reception terminals and store them in memory. The magnitudes to be memorized for each transmission system are the following: 1) number of erroneous bits within a suitable time window; . 2) alarms of ~he receiving and transmitting terminal and power-supply alarms; 3) pilot current of the LED (Light-Emitting Diode) in the transmission terininal; 4) temperature of the LED container in the transmission terminal; 5) current of the AGC (Automatic Gain Control) reaction ring in the reception ter- minal; _ 18 FOR OFFICIAL USE ONLY APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 APPROVED FOR RELEASE: 2007/02/49: CIA-RDP82-00850R440500040014-7 FOR OFFICIAL USE ONLY 6) polarization voltage of the APD (Avalanf�he Photodiode) in the reception ter- minal. The microprocessor assigns a sequential number to each data block, consisting of the abovementioned magnitudes relative to all the systems monitored, and in addi- " tion, calculates for each system the EFT*--a magnitude very significant for estab- lishing, together with the error rate,** the quality of the transmission. All these parameters characterize, for the time-interval considered, the state of the transmission systems being mon~tored, and t~ey constitute the data block that will be sent to the centralized processing organ on its request. The centralized processing organ synchronizes the ir~dividual microprocessors and periodically issues to them the order to send the last block memorized. In this way, it is capable of deducing the cause of any deterioration of transmission qual- ity. The error rate is checked as follows: when the centralized processing organ per- ceives that it has gone beyond preestablished thresholds, it memorizes on magnetic _ support the "history" of the transmission system whose quality has deteriorated. These measurement data are printed out and can be processed off-line to determine any eventual functions of statistical distribution of the errors. The measurement-data acquisition and processing system described is thus a typical example of a distributed-intelligence system; indeed, some of the functions to be performed have been assigned to the peripheral microprocessors. In this way, the - following advantages over a completely centralized structure were obtained: a) greater processing speed; - b) greater flexibili~.y of the structure; c) increase in overall reliability of the system. The microprocessor also performs the function of local monitoring of transmission systems: all the magnitudes stored in memory can in fact be visualized on a screen and the local operator is therefore enabled to perceive any malfunctions of the systems being monitored or deterioration of transmission quality. 6. Outlooks and Conclusions The continual technological evolution in the field of integrated circuits opens up n.ew prospects for the users of these devices. There are essentially two lines of approach identifiable in the construction of microprocessors apparatuses for trans- mission systems: a) In the cases in which these apparatuses have to process the signal in real time, the approach is to individuate very specific functions of the transmzssion system * EFT = minutes without error minutes of observation number of erreneous bits error rate - number of bits received 19 FOR OFFICIAL USE ONLY APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 FOR OFFICIAI. USE ONLY (for example: filtering, coding) and develop them with microprocessors specialized for such applications, which make possible a speed of treatment of the input sym- bols of some 10's of kHz. If it is necessary to increase the input-symbol processing speed beyond that limit, the approach expected is to design ad-hoc (custom) integrated circuits. Such a choice entails an integration of the tasks of the custom-circuit designer and of the person who defines th~ architecture af the system to be integrated. b) In those cases in which the m~croproc:essor apparatuses are intended to have sys- tem management or control functions, th~ approach is to use "single chips" in the minimal applications and 16-bit microprocessors when the data-processing problem is - complex. In both cases, the approach is to distribute the processing capacity in peripheral equipment, when the action of the controt or management system has to extend over a broad territory. BIBLIOGRAPHY 1. Fabbri, B., Sacchi, L., Tosco, F. and Veglio, G., "Hybrid-Type 140-Mbit/s Digi- tal Transmission System on Coaxial Cable," CSELT Technical Reports, Vol III, No 1, April 1975, pp 3-18. ELETTRONICA E TELECOMUNICAZIONI, XXV, 1976, p 135. 2. Tamburelli, G., "Digital Receiver with Distributed and Integrated Decision Feedback and Feedforward (to Overcome the Nyquist Barrier)," CSELT Technical Reports, Vol IV, No 4, December 1976, pp 199-209. 3. Bonaventura, G., Costa, B., Cottatellucci, 0., Daino, B., Esposto, F. and Lom- bardo, F., "COS 3/FOSTER Field Trial with an Optical Cable in Rome," paper pre- sented to the Sixth European Conference on Optical Communication, York, Septem- ber 1980. 4. Bonaventura, G., Catania, B., Gagliardi, D., Paladin, G. and Tosco, F., "COS 3/FOSTER: First Optical Fibre System for Operational Service in Italy," paper presented to the International Conference on Communications, Denver, June 1981. S. Esposto, F., Lombardi, F. and Paladin, G., "Results and Evaluations of the COS 3/FOSTER Optical-Fiber Experimenta~ilnstallation," ELETTRONICA E TELECOMUN- ICAZIONI, XXX, 1981, pp 79-85. COPYRIGHT: 19i4 by ERI-EDIZIONI RAI RADIOTELEVISIONE ITALIANA 11.267 CSO: 5500/2098 20 FOR OFF[CIAL USE ONLY APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500044014-7 FOR OFFICIAL 1!SE ONLY IT'ALY DIGITAL ftADIO-RELAY SYSTEMS AT 19 GHz IN URBAN AREAS _ Turin ELETTRUNICA E 1'E:LECOMIiNICAZIONI in Italian Nov-Dec 81 pp 247-252 _ [Article by P. Amadesi, R. Failli, G. Masone and L. rforeno*] [Text] Summary--Digital radio-relay systems operating at 19 GHz for metropolitan areas. In the near future, digital radio-relay links should connect telephdne ex- changes in metropolitan areas. The main problems related to the design and devel- opment of such systems are considered and some proposed solutions are discussed. First, the general system characteristics are dealt with and the choice of the 17.7 to 19.7 GHz band is justified, taking into account the expected hop length, link capacity, availability required, etc. The criteria for an efficient spectrum util- ization are next examined. The four-phase PSK seems to be the most feasible be- cause it represents the best compromise between bandwidth occupancy and interter- ence sensitivity in a multiple interference environment. Moreover, an effective procedure for automatic carrier frequency assignment has been adopted in ordFr to minimize the number of radio channels required. Finally the compatibility with satellite systems sharing the same frequency band is discussed and some preliminary _ results on coordination procedures are presented. 1. Introducticn The linl: network that connects urban telephone exchanges has until now used almost excliisi.vely paired cables installed in condui.t. In recent years, though, digital systems on cable have been introduced especially for the longer links, wtiere they offer the greatest advantages from the technical and economic point of view. The introduction of digital-type exchanges will broad- en the field of application of such systems, while in the future, optical-fiber _ cables will also be used in the same type of network. The digital radio-relay systems are a valid alternative or a complementary means in this field ot application, and they offer the following advantages: * k:ngineer Paolo Amadesi, En~ineer Luigi Moreno of the CSELT (Telecommunications Research and Study Center), Turin; Engineer Renzo Failli, Engineer Giorgio Masone ~f the SIP [Italian Telephone Company], General Administration, Rome. _ Typescript received 29 July 1981. This paper was presented to the In:ernatianal Conference on Communications, 1981. - 21 FOR OFF[CIAL USE ONLY APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 APPROVED FOR RELEASE: 2047102109: CIA-RDP82-00850R400504040014-7 ~'OR OFFICIAL USE ONLY ---~~ussibili.ty of i,nproving network availability by adopting diversified means of transmission (ca~le and radio) that are subject to breakdowns that have practic- - a11y no correlation with one another; --F~ossibility of making inexpensive relay links in areas of difficult topography; --possibility of making urgent connections in a short time. 'rurthermore, cost comparisons have shown that medium- and high-:apacity radio sys- tems are suitable, as against coaxial-cable systems, for connections longer than about 2 km ~Bibliography 1). _ The introduction o~ radio-rel~y systems into this new field requires a detailed ex- amination of various questio~~s. - The purpose of the present paper is to provide a concise description o� the main J problems to be tackled in the design and develapment of the new radio systema to be used in urban relay networks, illustratir.g also the principal solutions adopted. _ Section 2, in particular, presents the characteristics of the system anticipated for the 17.7-19.7 GHz band. In section 3 are discussed the criteria for efficient ' utilization of the spectrum within the urban environment, and an automatic proce- dure for a;signment of frequencies in a close-mesh radio network is cited. Section 4 examines the problem of the sharing of the 17.7-19.7 GHz band as between radio relays on lard and fixed services via satellite. L. Characteristics of the System ]n order to define the principal characteristics of the radio equipment to be used i.n the urban environment, and in particular the frequency band, the modulation method and the capacity per carrier, it is necessary to determine sufficiently closely the networic conFiguration, the distribution of the hop lengths ~nd the num- f~er oL circuits to be transmitted on each run. As tl~e first step, the visibility conditions between the urban telephone exchanges in the major Italian cities, both with a direct connection and through intermediale ~ centers, including the existing radio stations, were checked. The height of tt~e trestli~work possibly necessary for achieving the visibility conditions was assumed to be. limited to reasonable values, in order to respect the cities' environmental and esthetic requiremen~~ Vext, the compl?te co~ifigurations of the networks were determined, taking into ac- ~ount f~oth the visibilit}~ conditions and the preliminary assumptions relative to rlie breakdown, as between cable systems and radio systems, of the digital relay syste~ms anticipated in the next 20 years. In particular, it was assumed that the _ riini.miim r.un length would be limited to 1.5 km and that connecl-ions would not be made with more than 4 runs. ~~s an example, Figure 1 shows the network configuration planned in the metropolitan area of Rome; for each run, the capacity, expressed in number of 35.368-Mbit/s sys- tt_~ms (the third level of the European digital hierarchy), is indicated, _ 'I't~~~ final conLiguration of each urban network will necess,3rily depend on more pre- technical and economic considerations, including overall network availability, 22 FUR OFFICIAL USE ONLY APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 F~JR OFFICIAL USE ONL.Y tf~at will be possible only after an adequate period of experience with sy::tems in use. Never[heless, the preliminary results already obtained are sufficient for op- timizing the principal charac;:eristics of the system. ~ 1 2 2 ~ 8 2 _ 1 1 3 3 3 - 6 4 3 - 2 1 4 ~ 8 1 ~ 1 ~ ~ 2 t 2 ~ 1 4 5 1 3 i 4 2 6 1 1 1 5 7 6 1 3 Z 4 5 2 p 1 7 1 2 3 2 ~ 5 0 ~ 1 1 2 _ ~ 2 3 ~ ` 1 2 2 2 9905 Fi~;ure 1. Digital radio-relay network at 19 GHz planned in the area of the city of - Rome for the year 2000. The number marked on each run is the number oI 34-Mbit/s groups required for the run. w 30 ~~o~~ . J ~ J ~ W J Q ~ro f - 1 ~ ~ . r ~Q ~6 f i~f 3 l:~ ~ Z ~ ~ Y 10 ~ 4.:. f; ff ~4: ~ .i~l f43~ O a O ,e.y,~k' < S ~r� "r'S a ~~::a.: . ~ ~ t~ ~ O . 2 4.. 6 e ~ ( 2) ~UNGHEZZA OELLA TRATTA ( km) P'igure 2. Distribution of the run lengths Ke}~: 1. Percentage of the runs 2. I.ength of run (km) I~irst of all, two radio-channel capacity values were chosen: 34 Mbit/s and 140 ~lbit/s. It stiould be kept in mind that in the network planned for the ~irban - area of Rome, which will certainly be one of the biggest ones, the number of 34-Mbit/s systems required for each run is between 1 and 11, and the percentage of runs that require at least eight 34-hlbit/s systems, which would justify a digit speed of 280 Mbit/s, is very Zow. 23. FOR OFFICIAL USE ONLY APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 APPROVED FOR RELEASE: 2007/02/49: CIA-RDP82-00850R440500040014-7 FOR OFFICIAL USE ONLY G'i~ura 'L presents a histogram of the distribution uf the run lengths; it can be noted that the maximum length is approximately 10.5 km and that most of the runs are shorter than 6 km. In order to keep the unavailability times due to rain below reasonable limits (10 to 20 prime minutes per year) for each of the runs, using normal fading margins on the order of 40 dB, it emerges that ltaly's climatic conditions do not permit the use of bands higher than about 20 GHz (Bibliography 2). On the other hand, it is not suitable to use frequencies lower than 13 GHz, which would make it possible to have longer run lengths, since they are already assigned and used for medium- and long-distance connections. ~ A further requirement of the systems under consideration is that a rather high to- tal radio band be available in order to meet the capacity requirements of the nodes in whicil many runs converge. The 17.7-19.7 GHz band therefore appears the most suitable for this type of application. The ICCR [International Consultative Committee on Radiotelegriphy] recently ap-. ~roved the provisional text of a new recommendation relative to the plans for chan- nelization of this frequency band for radio-relay systems with capacity of about 280 Mbit/s, 140 Mbit/s and 34 Mbir/s (Bibliography 3). The plans recommended for the configuration with cochannel reuse of frequencies for the capacities of 14U rlbit/s and 34 :Ibit/s are shown in 'r'igure 3. As regards the modulation techniques, the considerations set out in section 3 in relation to dense radio networks indicate that four-phase PSK [expansion unknown] is the most suitable technique for the application examined in this paper. 'I'he radio-relay systems that operate at lower frequencies generally adopt some form of prote~tion (for example, difference of frequency or of spacing) in order to re- duce the effects oF the phenomena due to propagation and to improve the availabil- ity of tt,.e system as regards equipment breakdowns aLso. In the 17.7-I9.7 GHz band, attenuation from rain is the dominant effect of propagation because of the limited lengths of the runs, and therefore it is not possible to improve the system's availability due to the propagation factors except by careful choice of the run lengths and of the fading margins. Fur thes~. reasons, use of protection systems of the 1+ 1 type or the multiple-beam ty~~e could only improve availability as regards equipment breakdowns. In a~:~J~lications in urban areas where there is generally a diversified transmission, such as a cable network, it appears more appropriate to use unprotected svstems, with consequent economic and spectrum-use advantages. The equipment must, of co~�rse, be protected with sufficient reliability to obtain availability of the ronnections similar to that of the cable systems. 'fable 1 presents the typical values of the parameters relative ta the equipment and - the radio runs. In runs longer than 6 km, antennas of greater diameter (1.5 m) _ wi11 be used in order to augment the fading margin availahle. _ 24. . FOR OFFICIAL USE ONLY APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 APPROVED FOR RELEASE: 2047102109: CIA-RDP82-00850R400504040014-7 FOR OFFICIAL USE ONLY i W N ~ O ~ I 1 U G 41 y U O I ul cd N O U ~ a > G u ~ vai a~i v u G�~ j ~n T v w ~ ro s~ I N1 ~ e~~ u ~ o ~ ~ ~ G 'L7 3~ ~ w I~r O N~ ~ na. ~ - f~'I � 'G U 'L 'b '17 'Ll Cl' 1 "N ~ R1 Q1 N N ~ N M rl O~`1 n u N ~O b ch y.r C~ ~ G O ~ ^ ^ G u) cU ~ + I C~1 rA � ~ �C . ~ ^ i i = ro r~ ~G b a~ ~v v~ ~n E i F ~ v o � cn -d v v .a a rn a u~ ~n .c ~n ~ N u r-~ � ~p � t~ O ~.G x ~ I~t N O N G~. ~ C7 N~O n 7 d' y o0 b'' 1ro+ I y u � I~ t~ tn .C C 00 _ T N ~ . ~ ~ ~ a o u o I rn o N ~ oa a~ ca a�~ ~ a~ .o ~o a ~ ~ ^ v-d u ~ s~+ E a~i m~ tn ~ G G m cC N f~+ ~ c0 D, cn + I a L w v ~ ~ ~ ~ bD a1 O ~ L a'.� ~ I N m" v ro G aui ca o N w u G v a = w H ~ ~ ~ 3-i � ~ ~ O E o ~ x ~f ~n a~ u v ~ V G �o~ N 1 ~ a u M a~.~ G a c~C ~ w v o o ~ a~ .c 3 c~o c~o ~ u~ - ~ c~o � ~ a vo o a+ G 'b a m - - - - - .n N ~ G ~ a~ m v, m � ~ � ~ a1 ~ rn ~ v t~ 3-~ O O N U a1 a.~ O U G t1. ~ .L G ^O � ~ � r+ .a RS U O ~ N p,p p, tb 4J 3-+ O H T, i w a a u w a~ ~ i ~ u H o o v~ 0 4+ ~ ~ ~ ~ o v v s~ or~.~ i p'~ ~ .c >o o ~ a~i b r--~ cn ? s~ a o ~ v ~ � co N w 3~ y G w 41 ,C ~0 ~ cV - - - - - - ~ ~ S-+ 3 cAV avi ~ I4+ ~ ~ ~ ~ ~ � ~ ~ f~ al al E-~ H N u ~ O w p ~�a ~ a' w a~i ,N.~ 'x ~i~ ~ ~ ~ 0 " O 7 0~o v~ ~ u�~ ~O cts. � ~ ~n � v G ro ~ N w F u w ~ c~ v�,~ oo u ~d o a~ oa - - - - - - c cv v~ a' ~d 3 ~v ~ ~ 3 ~ � v N~ 4J �r+ OJ l~ O�~ �'-I �rl f~+ �~-1 u f~+ 7, .C .n a v a. v o ~ v v.c r+ u a w m u w ~ a u-+ a G'-+ v.a -d u u, o C~~, 4-, ~'tl o n� N G C a1 ctl 3-i �~-1 3-i cC � cv T p cv u C~+ a a~ f+ a�~ o cu v o0 3 u, cc o .n o v a+~ .o a co w o a 1 ~I ^ y 3�~ G ~ f~+ 41 N�a O N a C~ ~~0 O~n O Rl w v~ cU cd l~ u,~ 3~ ~ u�,~ ~n a s~ o i~ i�,~ .c~ o a, p � a a~ w o ~ � ~ u ,n 41 tSf ~ u~ o y al d0 N V' W r~ y~�.~ a1 3 G u v ~ N v+ a v~ v, o�.~ m y a~ v v v ro u � ~ ~n a ~o � ~ ~v �-a ~ s~ o~+ a a~ ~ o ~c c~ v, u ~ w~.HOxc~a w a o a ' ~ r~ f-G+ ~ ~u H a L~+ - .25. FOR OFF~CIAL USE ONLY APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-04850R000500040014-7 FOR OFF'ICIAL USE ONLY lation procedures have been developed for fast and accurate evaluation of the de- teriorations of PS~ signals in a multiple-interference environment (Biblio~;rapliy 7). In the preliminary phase of system definition, it was sought to evaluate the influ- ence of various design parameters on utilization of the spectz~im, by means of a generalized model based on the criteria and fundamental definitions of spectral ef- ficiency (Bibliography 8). The basic concept is that each radio connection, operated on a given frequency, prevents other connections from operating on that same frequency within a given re- gion, which depends on the transmitting power, the antenna pattert!s, the propaga- - tion characteristics, the demodulator's sensitivity to interferences, etc. Taking into accoucit the fact that the radio spectrum can be defined in the three dimensions of frequencies, physical space and time (Bibliography 8), one can evalu- ate the "quantity of spectrum (band X area X time) used" by any connection of the network. Finally, the efficiency of utilization of the spectrum can be expressed ~ as tt~e ratio between the quantity of information transmitted on a given connection _ and the spectrum used by that connection. ln a previous article (Bibliography 9), a detailed description was given of the model adopted. Below, several results are presented relative to the cfioice of mod- t~lation method in digital radia-relay networks at 19 GHz. 3.1. Examination of Modulation Methods The analysis model for utilization of the spectrum was applied vis-a-vis coherent PSK modulation systems with M phases. It is know that with the increase of M, the band occupied reduces, at equal transmission speed in terms of bit/s; neverttieless, with increase of M a more limited number of frequeucy reuses is acceptable, since _ sensitivity to interferences rises. e i E N t 0 6 ae /7=a ~ a 2a (1)~ ! ~r:2 e~ N 2 ~ z ~ ~ t6 p - ~ o . W o i z a a ( 2 ~ BIT/FORMA D'ONDA F'igiire 4. Efficiency of utilization of spectrum in a radio network with PSK modu- . lation with M phases. On the abscissa is the number of bits associated - with eac}~ wave form. Ke;: l. Spectral efCiciency (bit/s � Hz) 2. $it/wave-form Fig~lre 4 presents, for various values of M, spectral efficiency E, which is equiva- lent to the traffic capacity per band unit (bit/s�Hz) in a region of area equal to 26.~ FOR OFFICIAL USE ONLY APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-04850R000500040014-7 FOR OFFICIAL USE ONLY the mean quadratic value of the run length. Reference is also made to a parameter Y, which is indicative of the network density and is defined as follows: _ ~ Mean quadratic value of run length - Y N Total area covered by radio network in which N is the number of radio cente:-s in the network. Analysis of several actual cases has shown that Y= 2 and Y= 4 can be taken as re- presentative values for urban networks of inedium and high density, respectively. The results of Figure 4 are based on the following hypotheses: Transmission power equal on all runs Performance-characteristics threshold error probability = 10-3 with 40 dB fading margin Antenna pattern (diameter of paraboloid ICCR mask ~Iteport 614) with gain of = 1 m) 42.5 dB Performance-characteristics deterioration from total of interference 3 dB ( X= 1.6 PSK 2 and 4 phases Standardized channelization pitch ( X= 2.0 PSK 8 phases ( X= 2.3 PSK 16 phases Frequency reuse on cross-polarization ~ frequential %so YSK 2 and 4 phases ( interstitial' PSK 8 and 16 phases Parameter of density Y= 2 and Y= 4 Various other calculations were carried out, with different sets of parameters, in order to check, in the various cases, the best compromises for optimal use of the spectrum. In any case, Figure 4 can be considered quite significant. It shows that 4-phase PSK modulatiAn can be advised in this kind of application inasmuch as it achieves the best compromise between band occupation and sensitivity to inter- ferences, in a broad range of real situations. On the other hand, 2-phase PSK is the most efficient in very crowded networks and/or with antenna patterns that are not very directional. Eight-phase PSK, or - other multilevel modulations of high order, may be preferable when limited band oc- cupation becomes the dominant factor of spectral efficiency--that is, in low-dens- ity networks, such as the long-range ones. 3.2. Assignment of Transmission Frequencies - In the designing of a specific radio network, spectral efficiency can be optimized by careful coordination of the interferences. Since the number of connections may be very high, it is advisable for the assignment of the transmission frequencies to each run to be done by means of an automatic procedure. The procedure described in Bibliography 10 meets this requirement, assigning the frPquencies with the restriction of not exceeding a maximum level of interferinK * in the case of frequency reuse with interstitial method, it is intended that the carrier frequencies on horizontal and vertical polarization be staggered by one- half a channelization pitch. ,27. , FOR OFFICIAL USE ONLY APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000540040014-7 FOR OFFICIAL USE ONLY ~ower in each recE�iver and with ttie objective of minimizing the total number ~i carrier frequencies necessary in the entire network. The main advantage of thi.s procedure is represented by the possibility of easily various restrictions and of handling connections both of 34 Mbit/s and of 140 Mbit/s. In the system-defin~tion phase also, this procedure can be useful for analyzing the influence that various parameters (transmission power, antenna patterns, fading margins) have on the number of carrier frequencies required. Several preliminary tests of this procedure were carried out, using a network with topological characteristics similar to those expected in the major Italian cities (see section 2). These tests have confirmed the validity of the frequency-assign- = ment procedure and the possibility of intensive frequency resue. _ It was also verified ttiat the number of carrier frequencies required depends con- siderat~ly on the choice of the transmission powers and the fading mzrgins. Consid- er, for example, the two cases presented in Table 2. In the first case, it is as- sumed that the power transmitted and the fading margin are fixed independently of the run length, while in the second, the power transmitted in the shorter connec- tions (under 4 km) is considered reduced by 6 dB, so as to reduce overal interfer- - ence. In the shorter connections, it is also assumed thatthere is a reduced fading margin, but nevertheless one that is suffi.cient to ensure the availability required (t3ibliography 2). Table 2--Parameters Adopted for Automatic Assignment of Carrier Frequencies Hypothesis A Hypothesis B nigit Frequency Transmitted Fading Run Transmitted Fading _ Power Margin Length Power Margin 34 Ptbit/s 16 dBm 40 dB < 4 km 10 dBm 35 dB _ > 4 km 16 dBm 40 dB 14Q ,~1bit/s 22 dB 40 dB < 4 km ~6 dBm 35 dB > 4 km 22 dBm 40 dB In the second case, it emerges that the necessary number of carrier Erequencies is 25-percent less than in the first case. At present, other possible choices of transmitted power are being considered, keeping in mind the restrictions imposed by - tiie simplicity required for the operations of tuning and maintaining the equipment. The abovementioned calculations were done with adoption of the antenna-directional- ity ~nask proposed in ICCR Report 614 and assuming a 1-meter diameter of the parabo- lid antenna. This mask was used merely as the first point of reference, while fur- ther calculations are planned that will use the radiation patterns of antennas de- _ siKned for these applications. 4. Sharing of Frequencies with Fixed Services via Satellite '['he possible presence of fixed services via satellite t}iat share the entire 17.7- 19.7 Gtiz band, or part of it, with the fixed services on land, with primary-level allocation, is a fundamental problem to be examined for correct planning of a radio-relay network in an urban area. 28. FOR OFF[CIAL USE ONLY APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000540040014-7 FOR OFFICIAL USE ONLY " In the Iirst place, the antennas' t:ansmissions adhere to appropriate restrictions in ICCR Recommendations 358-2 and 406-4, so as to limit direct interference space transmitters in the ground receivers and from ground transmitters in the space receivers. Furthermore, the possible coexistence of radio-relay systems and earth stations re- ceiving or trans~;itting from a satellite in a common geographical area requires that the mutual interference~ be analyzed carefully, for correct coordination of the services. We illustrate several preliminary results relative to this question, obtained from from the case of two satellite systems that are being planned in Italy. a) ihe first problem examined concerns the earthward connection oF a national sat- - ~llite for telephonic communication with spot-beam coverages (Bibliography 11, - 13) of the nation's major cities. The connection planned for the satellice-to- earth run uses the 17.7-20.2 GHz band and transports high-capacity channels. 7'he earth stations receiving from the satellite must necessarily be situated within the metropolitan areas or in the immediate vicinity in order to be connected easily _ with the principal telephone-traffic switching centers. Consequently, all the ra- dio channels via satellite that are not comprised within the 19.7-20.2 GHz part of the band (which are assigned exclusively to service via satellite) undergo the in- terferences caused by the urban radio relays. ~ For an initial quantitative evaluation of this interference, we established con- servative hypotheses, assigning to the various par;imeters the numerical values giv- en in Bihliography 11, considering the antenna radiation pattern of ICCR Report - 390-3 for the earth-station antennas and examining the radio channels interfered wity in the most unfavorable way. The calculation results relative to the interferenc~ of a single transmitter of the radio-relay network in an earth station receiving from satellite are presented in Fifiure 5 in the form of "interference contours" on a topographical n?ap. Eact~ con- to�r is characterized by a constant value of the gain GR of the radio-rel.ay antenna in the direction of the earth station (ES) and represents the total of the minimum distances around the ES i.n which a network transmitter with antenna gain GR can be sited in such a way that tt~e C/I ratio at the earth-receiver input is equalto 35 dB. C/I is the ratio between the powers of the useful signal coming from the satellite in the sev~re fading conditions that cause rhe threshold condition of error rate of 10-3 and tne power of the nonfaded network interfering signal. The 35-d13 value of C/I is rather protective in a case in which there is only one interferin~; signal, and proves not very severe even if the radio network is dense; for example, 10 interfering signals with /equal frequency/ and with C/I = 35 dB each cause a total C/I ratio of 25 dB, which is therefore responsible for a consid- erable deterioration of the receiver's performance characteristics. Figure 5 shows that the distance required for limiting the interference from a single transmitter is a notable function of antenna gain GR and unfortunately can have values of several 10's of kilometers. Consequently, when the number of inter- fering transmitters of the network is high, tl-ie possible inclusion of stations re- 29 - FOR OFFICIAL USE ONLY APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000540040014-7 FOR OFFiCIAL USE ONLY 9 ceiving from the satellite to earth in an urban area of inedium extent appears - rather critical. zo ,Gp =20dB ~km~ ~ 1 ~ SA7 t3 ~ } ~ S \ 5 1p (km) _ 0 10 C~1 . 35dB - ~ 20 ~ Fi~ure 5. Sharing of frequency with the downward run of a national satellite for digital fixed services. Contours of interference in the case of a re- ceiving earth station (ES) and an earth radio-relay transmitter with an- tenna gain GR in the ES direction. C/I = 35 dB. The satellite's angle of elevation is 40�, a val~ie typical for Italy. Key: 1. Satellite ~ Gq ~ 1 - , 20d8 SAT 83 f 55 3 1 ~ ES 20 1 p p b C/I:25d8 i~f 0 0 ~ Fi~;ur~ 6. St~aring of freyuency with the upward connection of. a television-broad- casting satellite. Contours of interference in the case of a transmit- ting earth station (ES) and an earth radio-relay receiver with antenna gain C~ in tt~e rS direction. C/I = 25 dIi. The television satellite's angle of elevation is 30�, a value typical for Italy. Key: l. Satellite Assignment of the largest possible number of separate carrier frequencies to the two services therefore appears to be a requirement for reducing the complexity of coordination of the services. 30 FOR OFFICIAL USE ONLY APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500044014-7 FOR OFFICIAL USE ONLY b) The second problem concerns the earth-satellite connection (feeder link) for direct broadcasting of television signals that couZd operate in ~he 17.3-18.1 C:I1z band and therefore share the spectrum portion between 17.7 and 18.1 GHz with the other fixed services. - In the Italian case, the five channels assigned to Italy anci to the Vatican will probably fall within the sharing band (Bibliography 12), so that the power emitted from the transmitting earth station will cause interference in every earth receiver operating on those frequencies. The possibility of siting the earth transmitting station within the metropolitan area has been examined with che aid of the interference contours of Figure 6, ob- tained in a manner analogous to those for Figure 5. It was assumed that the EIRP (Effective Isotropic Radiated Power) of the eartti sta- tion in the direction of the satellite is equal to 65 dBW and that the transmittinb antenna has a diameter of 5 m radiation pattern in conformity with the ICCN charac- teristic (Report 39U-3); the curves relate to the most severe interferential situa- tion czused by the TV/FM channel most unfav~rably positioned in relation to a 34-Mbit/s digital channel. In Figure 6 there is only one source of interference--that is, the earth transmit- ting station--and the C/I ratio is therefore fixed at the critical value of 25 dEi. The situation certainly appears more severe than in the preceding case of Figure 5, - and topological coordination of the two services proves quite complex i_n those cases in which the metropolitan network is rather dense. Coordination of the ground services and those via satellite therefore constitutes - an open problem that calls for further investigation in depth. More detailed and closer analysis of the interferences examined in this section was subsequently un- dertaken and is reported in Bibliography 14. Acknowledgements Ttie authors thank ~ir L. Bassis and Pfr M. Ercolin for their efFective cooperation in carrying-out of this work. BIBLIOGRAPHY 1. "Uigital Radio Relays for Urban Areas in the 19-GHz band." SIP Internal Re- port, May ]980. " 2. Colavito, C., "New Systems in Radio Networks," Conference on Radio Relays, L'Aquila, May 1979. 3. ICCR, Study Group 9, "Radio Frequer..c~ Channel Arrangements for Digital Radio- Relay Systems in the 17.7-19.7 GHz Frequency Band," Proposal for New Recommend- ation, Doc 9/209, Interim Meeting, Geneva, October 1980. 31 FOR OFFIC[AL USE ONLY APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7 APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-04850R000500040014-7 FOR OFFICIAL USE ONLY 4. Colavito, C. and Sant'Agostino, M., "Binary and Quaternary PSK Radio Systems in a Multiple Interferer.ce Environment," IEEE TRANS. CONL'~ILiNICATIONS, Vol COr1-21, ~ Septembei� 1973, pp 1056-1067. 5. Ruthroff, C.L., Tillotson, L.C. and Prabhu, V.K., "Efficient Use of the Radio Spectrum and Bandwidth Expansion," PROC. IEEE, Vol 61, April 1973, pp 445-452. 6. Masone, G. and Moreno, L., "Optimal Use of Digital Radio Relays in Big Urban Areas," 22nd International Conference on Communications, Genoa, October 1974. 7. Amadesi, P., "A Fast Evaluation of the Error RatE in CPSK Systems with Inter- symbol and Multiple Cochannel Interferences by Means of Local Approximations of the Error Function," International Symposium on Information Theory, Santa Monica, Calif, February 1981, and CSELT TECHNICAL REPORTS, Vol 8, June 1981, pp 199-206. 8. lierry, L.A., "Spectrum Metrics and SpP~trum Efficiency: Praposed Definitons," IEEE TRANS. ELECTROMAGNETIC COMPATIBILITY, Vol EMC-19, August 1977, pp254-260. 9. Moreno, L., "Spectrum Utilization in a Digital Radio-Relay Network," to be published in IEEE TRANS. ELECTROMAGNETIC COMPATIBILITY. 10. Barberis, G. and Zingarelli, V., "Application of Network Optimization Algo- rithms to the Radio Frequenc~ Assignment Problems," International Conference on Communications, Denv~~r, June 1981. 11. Tirro, S. and Drioli, B., "Possibilities Offered by Artificial Satellites for National Communications in a Large European Country," TELECOM '79, Geneva. 12, Tomati, L., "Planning of a Television-Broadcasting System from Satelli.te," ELETTRONICA E TELECOMUNICAZIONI, September 1977, pp 182-194. 13. 13erretta, G. and Tirro, S., "New Telecommunications Systems at 20/30 GHz," International Conference on Communications, Seattle, June 1980. 14. Amadesi, P. and Failli, R., "Criteria for Sharing of Frequencies by Radio Re- lays and Earth Stations for Telecommunications via Satell.ite in a Large Urban ~rea," 29th International Conference on Communications, Genoa, October 1981. Cc)E'YItIGHT: 1974 by ERI-EDIZIONI RAI RADIOTELEVISIONE ITALIANA 11267 cs0: 55UU/2099 END 32 - FOR OFFICIAL USE ONLY APPROVED FOR RELEASE: 2007/02/09: CIA-RDP82-00850R000500040014-7