1、- STD-CEPT ERC REPORT 59-ENGL 1997 2326434 0013474 327 = ERC REPORT 59 v European Radiocommunications Committee (ERC) .- within the European Conference of Postal and Telecommunications Administrations (CEPT) REPORT ON CO-FREQUENCY CO-COVERAGE SHARING ISSUES BETWEEN TWO CDMA SYSTEMS Bucharest, Decemb
2、er 1997 STD.CEPT ERC REPORT 57-ENGL 1797 = 2326434 O033475 263 Copyright i 998 the European Conference of Postal and Telecommunications Administrations (CEPT) 5TD.CEPT ERC REPORT 59-ENGL L997 232b4L4 00L347b LTT REPORT ON CO-FREQUENCY CO-COVERAGE SHARING ISSUES BETWEEN TWO CDMA SYSTEMS 1 EXECUTIVE S
3、UMMARY 1 2 INTRODUCTION 3 3 THE AVERAGE CASE STUDY . 3 3.1 METHODOLOGY . 3 3.1.1 Introduction 3 3.1.2 The maximum external interference 3 3.1.3 Average noise produced by the system A into the system B 4 CALCULATIONS AND WORKING ssunos . 7 3.2. I For the calculation of Iext . 7 3.2.2 For the calculat
4、ion of the total noise produced by one system into the other 9 3.2.3 Conclusion on the working assumptions . 13 3.3 APPLICATION WITH THE CHARACTERISTICS OF GLOBALSTAR AND ODYSSEY SYSTEMS . 15 3.5 CONCLUSION . 25 3.2 3.4 RESULTS 17 4 THE OUTAGE CASE 26 4.1 INTRODUCTION 26 4.2 PROBABILITY CALCULATON 2
5、6 4.3 ALGORITHM . 27 3.4 APPLICATION TO GLOBALSTAR AND ODYSSEY SYSTEMS . 27 4.4 RESULTS AND CONCLUSION . 29 5 CONCLUSION . 30 ANNEX A CALCULATION OF FADING FACTOR AND RESULTS . 33 APPLICATION WITH THE GLOBALSTAR CHARACTERISTICS . 35 APPLICATION WITH COURIER FIGURES . 39 ANNEX B SELF-SHARING SCENARIO
6、 ANNEX C STD*CEPT ERC REPORT 59-ENGL 1997 = 2326434 0013Y77 U36 ERC REPORT 59 Page i REPORT ON CO-FREQUENCY CO-COVERAGE SHARING ISSUES BETWEEN TWO CDMA SYSTEMS 1 EXECUTIVE SUMMARY This paper is the synthesis of the studies presented in SE28 meetings on the co-frequency co-coverage frequency sharing
7、issues between CDMA systems. These studies have been performed by simulations of two CDMA systems sharing the uplink frequencies. As synchronisation between mobiles is not possible in the uplink, the internal noise of a CDMA system is greater in the uplink than in the downlink. Thus, it is generally
8、 agreed that the downlink is less critical than the uplink for the co-frequency co- coverage sharing issues. Some preliminary studies have been made also on the downlink, but the efforts have been concentrated on the uplink issue. The presented simulations have been run with the following working as
9、sumptions: The chosen fading probabiliy law applies for the ral environment (Goldhirsh, Julius and Woljhard J. Vogel, Propagation Effects for Land Mobile Satellite Systems: Overview of Experimental and Modeling Results, NASA Reference Publication 1274, 1992); It is assumed that the two systems have
10、coordinated their CDMA codes according to the ITU-Rec I186 so that they dont use the same CDMA codes; The traffic volume distribution between vehicle mounted mobile and handheld mobile is assumed to be 90% for the handheld terminals and 10% for vehicle mounted mobiles. This distribution is used in t
11、he average case via the fading factor calculation and in the blinding interference scenario; The user terminal power range depends on the type of the terminals (handheld or vehicle mounted mobile); Simulations based on the average case used characteristics of Globalstar and Odyssey systems. Simulati
12、ons to determine outage probability (blinding interference) assume identical systems with Globalstar characteristics. It should be noted that some preliminary studies have been made with the Courier system.; The value of the cross polarisation between the two systems can be estimated to be between O
13、 and 5 dB. It should be noted that, in case of sharing between more than two systems, the cross polarisation advantage is not available (3 OdB). 0 A first set of simulations was based on an average case. These simulations showed that, if no cross polarisation is taken into account, the maximum globa
14、l capacity of two sharing CDMA systems is equal to the larger maximum capacity of one single system. Thus, with no cross-polarisation and the characteristics of Globalstar and Odyssey, the calculations give the following figures: For Odyssey the maximum capacity is 3,3.10- active users per Hz. Globa
15、lstar maximum capacity is 4,4.10- active users per Hz. And in the case of co-frequency co-coverage sharing between Globalstar and Odyssey, the maximum global capacity is 4,4.10- active users per Hz. If a cross-polarisation advantage of 5 dB is considered, then the maximum global capacity of the 2 sh
16、aring CDMA systems is greater than the larger capacity of one single system: in the case of co-frequency co-coverage sharing between Globalstar and Odyssey, the maximum global capacity is 6,5.10- active users per Hz. In order to quanti the loss of capacity, when the two systems have the same volume
17、of traffic with no cross-polarisation advantage, the study of a theoretical self sharing scenario was proposed. That means that two CDMA systems have exactly the same characteristics. Considering two systems with Globalstar characteristics and the same volume of traffic, the simulation results show
18、that the loss of the capacity is from 9% to 28%, depending on the volume of traffic. The scenario, where one terminal of one system blinds one spot beam of the other system, has also been discussed: The percentage of ( blinding n interference with 5 dB cross polarisation isolation, given by the simu
19、lation with the working assumptions described above and the Globalstar and Odyssey characteristics, is from 0,02% in the case of a low volume of traffic (3.iO“active users /Hz) for the interference produced by Globalstar into Odyssey to 3,4% in the case of a high volume of traffic ( 1,7.lO“active us
20、ers /Hz). According to the CDMA operators at SE2 of CDM system is grealer h th; ,2lplink than in the downlink. Thus, it is generally agreed that the downlink is less critical than the uplink for the co- - frequency “_ - co-coverage - sharing issue. .- That is why .- this methodology includes only th
21、e uplink study. 3.1.2 The maximum external interference The maximum external interference level bearable by one system can be derived from the following equation: N total = Nth + Next + Nint The total noise in one channel of one spot beam equals the thermal noise in this spot beam and in this channe
22、l plus the external noise in this spot beam and in this channel plus the internal noise in this spot beam and in this channel. ERC REPORT 59 Page 4 The internal noise in one spot beam and in one channel is the noise of the other users in this spot beam and in this channel plus the noise of the users
23、 of the other spot beams of all the satellites operating this channel. The noise of the other channels is considered as insignificant. With: Othn spots. same channel =r. A. M. C. same spot. rame channel =A. (M-1). C. and r A M C = Aggregated spatial rejection factor of the spot beams. = Power contro
24、l factor models the imperfection of the power control. = Capacity: number of active users per beam and per channel. = Received power at the satellite for one user per spot and per channel. Moreover, the total noise can be expressed thanks to C, the received power at the satellite for one user (in a
25、spot beam and in a channel), and the required carrier to noise ratio. Thus, we can obtain: C.($).)- = Nth+Iextrn,+C.A. (M.(i+r)-1). Thus, the equation giving the maximum external interference bearable by a system can be derived as follows: With: IeXt C r A M Nth = Maximum external interference beara
26、ble by the system per spot and per channel. = Received power at the satellite for one user per spot and per channel. = Aggregated spatial rejection factor of the spot beams which are not perfectly disjoined. = Power control factor models the imperfection of the power control. = Capacity: number of a
27、ctive users per beam and per channel. = Thermal noise at the satellite of the system. = Required carrier to noise ratio. “9 Nota Bene: For the moment, it is not an average case. The received power at the satellite is assumed to be the same for each mobile operating in this spot beam and this channel
28、 thanks to the power control in order to maximise the capacity of the system. This is an intrinsic feature of all CDMA systems. 3.1.3 Average noise produced by the system A into the system B Considering two CDMA systems, system A and system B with a Co-frequency Co-coverage sharing. These two system
29、s have their own characteristics and a specific volume of traffic. The total noise produced for example by A into one channel and one spot beam of the system B is the addition of the following types of noise: 0 0 the noise produced by one channel of one spot beam of the system A into the co-frequenc
30、y channel and the co- coverage spot beam of the system B. the aggregated spatial rejection of the adjacent spot beams noise of the system B. the noise of non-Co-frequency channels from A into the system B, but this type of noise is considered as insignificant. ERC REPORT 59 Page 5 To summarise, the
31、total noise produced by the system A into one spot beam and one channel of the system B is the noise produced by one spot beam and one channel of A into the spot beam of B (shown as ( 1 ) in the Figure I) plus the noise spatially rejected from the adjacent spot beams of system B (shown as ( 2 ) in t
32、he Figure 1). The Figure 2.1.a explains these two types of noise. Figure 1: Noise produced by the system A into the system B. / /i / / / / i / w- / i SYSTEM A SYSTEM B ( 1 : Noise produced by A into one spot beam and one channel of B. i ( 2 D: Noise spatially rejected from the adjacent spot beams of
33、 system B. 71 i he total noise produced by the system A into one spot beam and one channel of the system B is given by the following :quation: N-total mm A into = -k rB . by onespoi beam of A into B With: N-total from A into rB N by = Total noise produced by A into one spot beam and one channel of B
34、. = Aggregated spatial rejection factor of the system B. = Noise produced by one spot beam of A into one spot beam of B. beam of A into The noise produced by the system A into the system B, considering only one spot beam, can be calculated thanks to the following formulae: With: N byoncspotbeamof MA
35、 =Noise produced by the user terminals of A into the satellite of B. = Capacity of A (number of active users per beam and per channel). = Spot area ratio between the system B and the system A. Spot- size, Spot- size, sTD.CEPT ERC REPORT 59-ENGL 1997 = 2326434 0013482 413 ERC REPORT 59 Page 6 = Satel
36、lite antenna gain ratio between the systems B and A. Ant- Gainsateliiie-B Ant- Gainsateiiite-A B+A CA = Altitude ratio. = Frequency bandwidth ratio. = Fading factor which models the propagation difference. = Received power at the satellite of A for one user of A (/spot.channel). Thus, by combining t
37、he two previous equations, we can easily derive the equation given the total noise produced by the system A into one spot of the system B: . With: Ntotal from A into B. it i rB MA Spot- size, Spot- size, Sat- ant- gain, Sat- ant- gainA = Total noise produced by A into one spot and one channel of B,
38、at one instant t. = Aggregated spatial rejection factor of the system B. = Capacity of A (number of active users per beam and per channel). = Spot area ratio between the system B and the system A. = Satellite antenna gain ratio between the systems B and A. = Altitude ratio between system A and B. =
39、Frequency bandwidth ratio. = Fading factor which models the propagation difference, at one instant t. = Received power at the satellite of A for one user of A (/spot.channel). Nota Bene: At one instant 2 the equation (2) does not model an average case, but a real case. To study the average case, the
40、 average value of the fading factor B+A over the time shall be used. This average value leads to the average total noise produced by one system into the other. (See paragraph 2.2.2 on the calculation of the fading factor for more details). .*.pq *,“ -, T-w“-9 -, -C.L“.-IIII.V-.-il-“-, “.-c-n- - .*-
41、I x _. *.(* -,- If in one spot beam and in one channel, the fading factor isghigher, we can expect that it will not be the case Ci*) 0,75 3- Minimum receivedpower in a spot beam for one Odys. voice user min. receivedpow. (d W/2,5MHr) -161,17 C/Nth (dB) -22,68 (Odys. - GI*) I ,26 4- Average receivedp
42、ower in a spo beam for one Odys. voice user m. receivedpow. (d W/2,5MHz) -149,65 C/Nth (dB) -1 1,15 r (Odys. - GI*) 0,93 STD-CEPT ERC REPORT 59-ENGL 1777 D 232b414 0033492 342 ERC REPORT 59 Page 16 Globalstar system I- System values altitude (m) spot size ratio: G*/Odys. ratio: Gsat-G* / Gsat-Odys.
43、bandwidth ratio: G*/Odys. bandwidth (Hz) channel number (Eb/NO)req (dB) average user data rate (bids) k delta alpha r system noise temperature (K) Nth (dBW/1,23MHz) frequency (MHz) frequency re-use factor capacity max per channel cross-polarisation with Odyssey (dB) (CWreq (dB) 1414000 1,28 0,04 0,4
44、9 1,23E+06 9 491 2880 -22,20 1,38E-23 1,35 0,375 1-1 520 -140,55 1,6 1E+09 1 4,40E+O1 5 2- Maximum receivedpower in a spot beam for one G*. voice user Avg. mobile satellite distance(m) 2,80E+06 tx power (dBW/1,23MHz) 0 Free space loss (dB) -165,52 Sat antenna Gain (dB) 13,89 max receivedpow. (dBW/1,
45、23MHz) -151,63 C/Nth (dB) -1 1,08 (GI*- Odys.) 1,41 3- Minimum receivedpower in a spot beam for one G*. voice user min receivedpow.(dB W/1,23MHz) -160,75 CNth (dB) -20,20 r (Gl*- Odys.) 2,34 4- Average receivedpower in a spot beam for one G*. voice user avg. receivedpow. (dB W/1,23MHz) -154.13 C/Nth
46、 (dB) -1339 (GI*- Odys.) 1,65 ERC REPORT 59 Page 17 3.4 Results If no cross-polarisation isolation is considered: Consider both systems operating at the minimum level. In Figure 3, we can see 4 curves: IexLmax bearable by Globalstar in one of its carriers, assuming a capacity of active users per Hz,
47、 the noise produced by Globalstar into one Odyssey channel of a spot in function of the capacity of the Globalstar system, and the same type of curves for Odyssey. Figure 3 G (Cmin) - Odys. (Cmin) -1 90,oo -195,OO -200,oo -2 05, O O N F 2 -210,oo U -21 5,OO -220,oo -225,OO -230,OO users per Hz 1 I I
48、 ext rnax G*. - G - odys. - I ext rnax 0dys.l - - 0dy. - G I- With: for Globalstar: Creceived=Cmin for Odyssey: Creceived=Cmin This figure shall be interpreted as follows: The horizontal axis represents the active users per Hz of each system. For example, the point at 1,3e-5 users per Hz means for G
49、lobalstar 1,3e-5*1,23MHz, thus i6 active users per channel and per beam. For Odyssey, it means 1,3e-5*2,5MHz, thus 32,5 active users per channel. This is twice as large as for Globalstar, but it is logical because the Odyssey channel bandwidth is twice that of the Globalstar one. The active users per Hz concept is one way to compare efficiently the level of traffic, because its independent of the channel bandwidth of the systems. The IeXt max curve represents the external interferenc
