1、European Radiocommunications Committee (ERC) within the European Conference of Postal and Telecommunications Administrations (CEPT) COMPATIBILITY BETWEEN MSS (SPACE-TO-EARTH) IN THE BAND 1559 - 1567 MHz AND ARNS/RNSS INCLUDING GNSS IN THE BAND 1559 - 1610 MHz Marbella, February 1999 STD-CEPT ERC REP
2、ORT 70-ENGL L777 .P 232b414 001b23b Y23 ERC REPORT 70 Copyright 1999 the European Conference of Postai and Telecommunications Administrations (CEFT) . INDEX TABLE 1 INTRODUCTION 1 2 MSS SYSTEMS 1 3 RNSS SYSTEMS 1 4 SCENARIOS . 2 5 SUMMARY OF RESULTS . 2 5.1 5.2 5.3 5.4 INTERFERENCE FROM MSS INTO GPS
3、 . 2 INTERFERENCE FROM MSS INTO E-NSS-1 3 INTERFERENCE FROM MSS INTO LSATNAV 3 INTERFERENCE FROM E-NSS-1 INTO MSS . 3 DISCUSSION OF RESULTS 4 GENERAL CONSIDERATIONS OF BAND SHARING 4 SHARING BETWEEN PROPOSED MSS AND GPS 4 SHARING BETWEEN PROPOSED MSS AND NEW PROPOSED RNSS NETWORKS . 4 5.5 INTERFEREN
4、CE FROM MSS INTO PSEUDOLS 3 6 6.1 6.2 6.3 7 CONCLUSIONS . 5 Annex I Annex 2 Annex 3 Annex 4 Annex 5 Annex 6 Interjerence from MSS into GPS current and planned networks 7 Interjerence from MSS into ESA E-NSS-1 Network including Consideration of Mutual Interference between MSS and RNSS Networks 18 Sha
5、ring study between MSS (Space-to-Earth) and the LSATNAV system 29 Interjerence from E-NSS-I into MSS 36 Interference from MSS into Pseudolites . 39 Discussion of multiple MSS networks . 40 STD-CEPT ERC REPORT 70-ENGL 1777 W 232b419 00Lb238 2Tb ERC REPORT 70 Page 1 COMPATIBILITY BETWEEN MSS (SPACE-TO
6、-EARTH) IN THE BAND 1559 - 1567 MHz AND ARNSRNSS INCLUDING GNSS IN THE BAND 1559 - 1610 MHz 1 INTRODUCTION ITU Resolution 220 (WRC-97) “requests the ITU to study the technical criteria and operational and safety requirements to determine if sharing between the aeronautical radionavigation and radion
7、avigation-satellite services operating, or planned to operate in the band 1559 - 1610 MHz, and the mobile-satellite service in a portion of the 1559 - 1567 MHz frequency range, is feasible”. GPS and GLONASS are established RNSS systems operating in the 1559 - 1610 MHz band. These systems are widely
8、used with a range of different applications. In particular, it should be noted that these systems are already used for safety-of-life applications. In addition to GPS and GLONASS plans have been published for second-generation RNSS systems, among others by ESA as E-NSS-1 and by France as LSATNAV (kn
9、own as INES). Also, plans for terrestrial, GPS-like transmissions from so- called pseudolites are being discussed. This report presents studies on the compatibility between proposed MSS (space-to-Earth) in the 1559 - 1567 MHz band and GPS, GLONASS, E-NSS-1, LSATNAV and pseudolites in the 1559 - 1610
10、 MHz band. 2 MSSSYSTEMS Various types of MSS services can be provided with a range of PFD levels. The required PFD depends mainly on modulation and access technique, MES receiver G/T and required link margin. For example, TDMA systems using QPSK modulation and providing service to handheld terminals
11、 require PFD levels of up to around -100 dB (W/m2/MH.z). Other types of MSS services could be operated at lower PFDs using MES terminals with some antenna directivity. In particular, it is estimated that a range of viable MSS services can be implemented at a PFD of around -1 12 dB(W/m2/MHz). Broadba
12、nd services, for example as part of the UMTS, would have to be provided through MES terminals with some antenna gain, due to the increased MES EIRP requirements. Some types of vehicular applications also use MES terminals with some directivity. In addition, various types of semi-fixed and fixed appl
13、ications using directional antennas are provided today as extensions of the main-stream MSS services. Thus, while a PFD-constrained MSS allocation would limit the range of applications and types of MSS systems that could be implemented, such an allocation would nevertheless benefit the MSS, especial
14、ly if the band was used as a complement to other allocations. Based on the discussion in Annex 6, the assumption should be that only one MSS system will be operating at a given frequency in a given coverage area. 3 RNSS SYSTEMS The GPS system i uses the carrier frequency 1575.42 MHz which is modulat
15、ed by two different codes, a Precision Code (P-Code) and a Coarse / Acquisition Code (UA-Code). The chip rates of these codes are 10.23 Mchip/s and 1.023 Mchip/s respectively, corresponding to 3 dB bandwidths of approximately 24.5 MHz and 0.45 MHz respectively. As the analysis in Annex 1 shows, sign
16、ificant discrimination would therefore be available between GPS and a MSS allocation in the band 1559 - 1567 MHz. The calculations in Annex 1, of interference from the MSS into the GPS system, were based on the GPS interference protection requirements defined in Recommendation ITU-R M. 1088 2. The G
17、LONASS-M 3 frequency plan will have three stages of development. The lowest carrier frequency used will be 1598.0625 MHz (as of stage 2). GLONASS-M uses P- and C/A-Code chip rates of 5.11 and 0.5 11 Mchip/s respectively. Thus, it will be fair to assume that if GPS is protected, GLONASS would also be
18、 protected, since the frequency separation from the proposed MSS allocation to GLONASS is greater than to GPS. The increased discrimination from larger frequency separation would offset the differences due to more stringent protection requirements for GLONASS. STD=CEPT ERC REPORT 70-ENGL 1779 I232b4
19、14 001b239 132 ERC REPORT 70 Page 2 The European Space Agency, ESA, with the support of the European Commission and of user groups including Eurocontrol, is planning a second-generation RNSS network which has been advance published by ITU under the name E- NSS-I, which would use the bands 1559 - 156
20、3 MHz and 1588 - 1592 MHz 4. The parameters of this system were used as an example of a possible future RNSS system for the assessment of the Co-frequency sharing feasibility. CNES, the French Space Agency, and Alcatel are currently studying the implementation of a second-generation RNSS system. Alc
21、atel, under contract from the European Commission, is planning this RNSS system, known as INES (Innovative Navigation European System), which has been advance published by ITU under the name of LSATNAV 5. This system would also use the frequency bands 1559 - 1563 MHz and 1588 - 1592 MHz. 4 SCENARIOS
22、 Five scenarios are analysed: 1) 2) 3) 4) 5) Interference from MSS into GPS (See Annex 1) Interference from MSS into E-NSS-1 (See Annex 2) Interference from MSS into LSATNAV (See Annex 3) Interference from E-NSS-1 into MSS (See Annex 4) Interference from MSS into pseudolites (See Annex 5) In additio
23、n, considerations of the mutual interference between MSS and E-NSS-1 are included in Annex 2 and a justification for the assumption that only one MSS network will be received in any place in any part of the frequency spectrum is given in Annex 6. 5 SUMMARY OF RESULTS 5.1 The single entry interferenc
24、e power flux density limit to protect existing GPS receivers against a MSS signal in a portion of the band 1559 - 1567 MHz is dependent on the proportion of the band used and the GPS receiver type against which this is being assessed. Interference from MSS into GPS Five scenarios are developed in An
25、nex 1, all assuming that one fourth of the interference allowance is allocated to the MSS. The worst case found is for existing GPS receivers using the CIA-Code for civil aviation. The power flux density (PFD) limit needed to protect these systems from a MSS signal in the band 1559 - 1567 MHz is -1
26、14 dB (W/m*) in any 1 MHz. This figure is based on the ICA0 assumption that the worst-case RNSS receiver antenna may have a peak gain of +7 dBi and a minimum gain, at 85“ off axis, of -4.5 dBi. The feasibility of such an antenna has been questioned. Calculations based on an alternative antenna, char
27、acterised by a +3 dBi maximum gain, relax the PFD limit to -1 10 dB (W/mz) in any 1 MHz. In the future though, enhancements and additional frequencies are being offered to the civil community. One of these frequencies is likely to be 1565.19 MHz. In this instance, a MSS signal in the band 1559 - 156
28、7 MHz will overlay this signal. In this case a PFD limit of -139.5 dB (W/m2) in any 1 MHz is required to protect the new GPS frequency. If the MSS band is reduced to only 4 MHz, i.e. 1559 - 1563 MHz, the required PFD limit would be -121.8 dB (W/m2) in any 1 MHz. There was also concern that these PFD
29、 levels correspond to a tolerable increase of noise of only about 2%, which implies that GPS is much more sensitive to interference than either E-NSS-1 or LSATNAV. Annex 1 derives the maximum PFD limits that need to be applied to MSS signals to protect the use of GPS and to allow the satisfactory de
30、velopment of its various applications. However, it has been assumed that the spectra of transmitted MSS signals may be considered as approximating to gaussian white noise. Further study would be required to determine the interference effect if the actual modulations used are such that this assumptio
31、n is not tenable. In addition the ITU defines PFD in three different ways, as an absolute limit, as an aggregate limit and as an effective limit. The latter two relate to the operation of non-GSO satellite systems. However, the interference from the proposed GSO MSS systems into the RNSS is static,
32、so that the PFD limits derived in Annex 1 have no statistical element and no reduction in PFD levels can be considered. STD-CEP“ ERC REPORT 70-ENGL 1799 9 232bVlV 00lb240 954 - ERC REPORT 70 Page 3 5.2 Annex 2 shows that the current design of E-NSS-I, based on a transmitter with 80 W output power an
33、d an optimised Earth- coverage antenna, there is a 3 dB margin between the carrier to (thermal plus intra-system) noise, C/No+Po, of 44.3 dBHz and the required overall C/No (= C/No+Po+Io) of 41.2 dBHz. On this basis, the maximum tolerable single-entry interference power spectral density at the outpu
34、t of the antenna of an E-NSS-1 receiver is -207.3 dB (W/Hz), which corresponds to a maximum power flux density limit for a geostationary MSS satellite of -125 dB (W/mz) in any 1 MHz and to a tolerable noise increase of 27%. Interference from MSS into E-NSS-1 This limit is based on the assurance (sup
35、ported by Annex 6) that only one satellite could be visible in any part of the frequency band from any RNSS receiver, and on the assumptions that one fourth of the interference allowance is allocated to the MSS and that the MSS signal can be approximated as additive gaussian white noise. It has been
36、 suggested that E-NSS-1 could overcome the interference from the proposed MSS networks by increasing its satellite transmitter power. Annex 2 shows that the imposition of MSS (at the stated operating power flux density of -1 12 dB (W/m2) in each 1 MHz) in the band 1559 - 1567 MHz would cause the max
37、imum tolerable interference to E-NSS-1 to be exceeded by 5.4 dB and that increasing the E-NSS-1 transmitter power to the point where the negative margin caused by the MSS network is been balanced out would require an increase in transmitter power from 80 watts to 310 watts (which, it should be recal
38、led, can not be achieved using current predictions of technological capability). Moreover, as is discussed in Section 5.4 below, Annex 2 also shows that this increased E-NSS-1 transmitter power would appear to decrease the operating margin of the MSS networks by 4 dB. 5.3 Annex 3 presents analysis o
39、f the tolerable interference into LSATNAV based on degradation of noise by the MSS system in the LSATNAV receiver. The MSS PFD limits corresponding to noise degradations of 6% (0.25 dB) and 25% (1 dB) are respectively -135.4 dB (W/mz) and -129.0 dB (W/m2) in any 1 MHz. Interference from MSS into LSA
40、TNAV However, as sharing between MSS systems on a Co-frequency and Co-coverage basis is not practical, regulatory provisions should be adopted in order to preclude this (for instance a footnote stating that sharing between MSS systems in 1559 - 1567 MHz should only be permitted on a band segmentatio
41、n basis). The PFD limit obtained for 25% of noise degradation would then correspond to the contribution of a single MSS system. With this limitation, the introduction of a new allocation to MSS in the Space-to-Earth direction in the 1559 - 1567 MHz band would be compatible with the planned LSATNAV s
42、ystem under the condition that a maximum PFD level of -129 dB (W/m2) in any 1 MHz be respected by each MSS network. 5.4 The analysis of mutual interference between MSS and RNSS networks presented in Annex 2 shows that the penalty to the MSS network of band sharing exceeds 3 dB if the planned charact
43、eristics of E-NSS-1 are used and exceeds 7 dB if the transmitter power of E-NSS-1 is augmented to overcome the interference from the MSS network. Interference from E-NSS-1 into MSS However, Annex 4 shows that it is nevertheless possible to design a mobile-satellite system which would operate satisfa
44、ctorily in the presence of Co-frequency interference generated by the E-NSS- 1 system, even if the E-NSS-1 power is augmented in order to overcome the MSS interference, if the mobile earth station (MES) is equipped with a directional receiving antenna having a gain of some 12.5dBi and uses robust mo
45、dulation and coding techniques, such as QPSK modulation and 1/2-rate convolutional forward-error-correction (FEC) coding. 5.5 Annex 5 presents an analysis of the possible interference from MSS networks into pseudolites at 1561.19 MHz. Assuming that the signal level received by the RNSS receiver woul
46、d be similar to that received from GPS satellites, it is calculated that a PFD limit between -121.6 and -125.4 dB (W/m2) in any 1 MHz would be needed. Interference from MSS into pseudolites However, it may be assumed that the pseudolites will need to transmit at higher powers than satellites at the
47、equivalent range. Airborne receivers of pseudolites are expected to use the same antennas as for satellites, so will see the pseudolites with low gain at negative elevation angles. Land-based receivers will see the pseudolites with increased path losses due to terrain obstruction. Being ground-based
48、, higher pseudolite transmitter powers will be practicable. As a consequence, the STD*CEPT ERC REPORT 70-ENGL 1979 .I 232b4111 001b241 870 ERC REPORT 70 Page 4 interference into MSS receivers (MES) from pseudolites may be significantly higher than from navigation satellites. However, this is a local
49、ised problem. 6 DISCUSSION OF RESULTS 6.1 Successful sharing requires the loss of orthogonality in frequency and thus depends on that availability of orthogonality in space or time. For example, MSS (space-to-Earth) shares successfully with FS because satellites operate when they are above the horizon while terrestrial stations are fixed to the Earths surface. Also, RNSS shares successfully with certain radar systems because RNSS uses continuous signals while radar uses pulsed signals. Also, RNSS can support limited out- of-band interference from MSS (Earth-to-space) because
