1、 ETSI TR 102 443 V1.1.1 (2008-08)Technical Report Satellite Earth Stations and Systems (SES);Satellite Component of UMTS/IMT-2000;Evaluation of the OFDM as a Satellite Radio InterfaceETSI ETSI TR 102 443 V1.1.1 (2008-08) 2 Reference DTR/SES-00252 Keywords satellite, UMTS ETSI 650 Route des Lucioles
2、F-06921 Sophia Antipolis Cedex - FRANCE Tel.: +33 4 92 94 42 00 Fax: +33 4 93 65 47 16 Siret N 348 623 562 00017 - NAF 742 C Association but non lucratif enregistre la Sous-Prfecture de Grasse (06) N 7803/88 Important notice Individual copies of the present document can be downloaded from: http:/www
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6、foregoing restriction extend to reproduction in all media. European Telecommunications Standards Institute 2008. All rights reserved. DECTTM, PLUGTESTSTM, UMTSTM, TIPHONTM, the TIPHON logo and the ETSI logo are Trade Marks of ETSI registered for the benefit of its Members. 3GPPTM is a Trade Mark of
7、ETSI registered for the benefit of its Members and of the 3GPP Organizational Partners. ETSI ETSI TR 102 443 V1.1.1 (2008-08) 3 Contents Intellectual Property Rights5 Foreword.5 1 Scope 6 2 References 6 2.1 Normative references .6 2.2 Informative references6 3 Definitions, symbols and abbreviations
8、.7 3.1 Definitions7 3.2 Symbols8 3.3 Abbreviations .8 4 OFDM technology and background.9 4.1 OFDM Fundamentals .9 4.1.1 OFDM Definitions9 4.1.2 OFDM Signal Generation.10 4.1.3 Guard Interval.11 4.1.4 Impact of Guard Interval.12 4.1.5 Impact of Symbol Duration 12 4.1.6 Impact of Inter-Carrier Spacing
9、12 4.1.7 OFDM Inactive Sub-Carriers12 4.1.8 Time-Frequency Multiplexing13 4.1.9 OFDM Signal Reception Using the FFT 14 4.2 OFDM for Mobile Terrestrial and Satellite Scenario .14 5 OFDM and the satellite environment .15 5.1 Non-Linearity Effects and Predistortion Techniques .15 5.1.1 Compensation Tec
10、hniques15 5.1.2 Digital Predistortion Techniques 16 5.1.3 Multi-Beam Coverage Using OFDM16 6 OFDM feasibility .17 6.1 Physical Layer Structure in the OFDM Downlink .17 6.1.1 Physical Channel 17 6.1.1.1 OFDM Physical Channel Definition .18 6.1.2 Channel Coding and Multiplexing19 6.1.3 Physical Channe
11、l Mapping .20 6.1.4 User Traffic Multiplexing Solutions.20 6.1.4.1 Solution based on a generic Costas sequence .20 6.2 Spectrum Compatibility .22 7 OFDM Evaluation Scenario .23 7.1 Reference System Scenario for OFDM S-DMB Analysis23 7.2 Reference OFDM configurations for the evaluation 24 8 Simulatio
12、n Results25 8.1 Uncoded System Performance .25 8.1.1 AWGN Channel25 8.1.2 Non-linear channel26 8.2 WCDMA Coding Performance 27 8.2.1 Non selective Rice fading .29 8.2.2 Frequency Selective Channel30 9 Link Budget Study .36 9.1 System parameters36 9.1.1 Satellite parameters.36 9.1.2 UE parameters 36
13、9.1.3 Physical layer configuration and performances 36 ETSI ETSI TR 102 443 V1.1.1 (2008-08) 4 9.2 Link budgets.37 9.2.1 Handset .37 9.2.2 Handheld.38 9.2.3 Vehicular 39 10 Conclusions 39 History 41 ETSI ETSI TR 102 443 V1.1.1 (2008-08) 5 Intellectual Property Rights IPRs essential or potentially es
14、sential to the present document may have been declared to ETSI. The information pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found in ETSI SR 000 314: “Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs not
15、ified to ETSI in respect of ETSI standards“, which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web server (http:/webapp.etsi.org/IPR/home.asp). Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee c
16、an be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web server) which are, or may be, or may become, essential to the present document. Foreword This Technical Report (TR) has been produced by ETSI Technical Committee Satellite Earth Stations a
17、nd Systems (SES). ETSI ETSI TR 102 443 V1.1.1 (2008-08) 6 1 Scope The present document entails a feasibility study that evaluates the use of the OFDM Radio Interface proposed the 3GPP TR 25.892 i.1 as Satellite Radio Interface on the satellite downlink, presenting physical layer results and link bud
18、get studies. The present document contains informative elements that should serve as a starting point for the definition and finalization of advanced Satellite Radio Interfaces. The adoption of the OFDM Radio Interface results in higher link margin under key propagation conditions such as the NLOS p
19、ropagation case and when CGCs are considered. 2 References References are either specific (identified by date of publication and/or edition number or version number) or non-specific. For a specific reference, subsequent revisions do not apply. Non-specific reference may be made only to a complete do
20、cument or a part thereof and only in the following cases: - if it is accepted that it will be possible to use all future changes of the referenced document for the purposes of the referring document; - for informative references. Referenced documents which are not found to be publicly available in t
21、he expected location might be found at http:/docbox.etsi.org/Reference. For online referenced documents, information sufficient to identify and locate the source shall be provided. Preferably, the primary source of the referenced document should be cited, in order to ensure traceability. Furthermore
22、, the reference should, as far as possible, remain valid for the expected life of the document. The reference shall include the method of access to the referenced document and the full network address, with the same punctuation and use of upper case and lower case letters. NOTE: While any hyperlinks
23、 included in this clause were valid at the time of publication ETSI cannot guarantee their long term validity. 2.1 Normative references The following referenced documents are indispensable for the application of the present document. For dated references, only the edition cited applies. For non-spec
24、ific references, the latest edition of the referenced document (including any amendments) applies. Not applicable. 2.2 Informative references The following referenced documents are not essential to the use of the present document but they assist the user with regard to a particular subject area. For
25、 non-specific references, the latest version of the referenced document (including any amendments) applies. i.1 3GPP TR 25.892 (V6.0.0): “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Feasibility Study for Orthogonal Frequency Division Multiplexing (OFDM) fo
26、r UTRAN enhancement (Release 6)“. i.2 3GPP TR 25.858 (V5.0.0): “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; High Speed Downlink Packet Access: Physical Layer Aspects (Release 5)“. ETSI ETSI TR 102 443 V1.1.1 (2008-08) 7 i.3 ETSI TS 125 212: “Universal Mobi
27、le Telecommunications System (UMTS); Multiplexing and channel coding (FDD) (3GPP TS 25.212 version 5.9.0 Release 5)“. i.4 S. Chang: “Compensation of nonlinear distortion in RF power amplifiers“, Wiley Encyclopedia of Telecommunications, J.J. Proakis Ed., 2002. i.5 S. Benedetto and E. Biglieri: “Nonl
28、inear equalization of digital satellite channels“, IEEE J. Select. Areas Comm., vol. 1, pp. 57-62, Jan. 1983. i.6 J.K. Cavers: “Amplifier Linearization using a digital predistorter with fast adaptation and low memory requirements“, IEEE Trans. Vehic. Tech., vol. 39, pp. 31-40, Nov. 1990. i.7 P. Salm
29、i, M. Neri, and G.E. Corazza: “Fractional Predistortion. Techniques with Robust Modulation Schemes for Fixed and mobile Broadcasting“, 13th IST Mobile 24:153-167, published online in Wiley InterScience (). DOI: 10.1002/sat.836. 3 Definitions, symbols and abbreviations 3.1 Definitions For the purpose
30、s of the present document, the following terms and definitions apply: cell: geographical area under Complementary Ground Component coverage downlink: unidirectional radio link for the transmission of signals from a satellite to a UE forward link: unidirectional radio link for the transmission of sig
31、nals from a gateway to a UE via a satellite guard interval / guard time: number of samples inserted between useful OFDM symbols, in order to combat inter-OFDM-symbol-interference induced by channel dispersion and to assist receiver synchronization NOTE: It may also be used to aid spectral shaping. T
32、he guard interval may be divided into a prefix (inserted at the beginning of the useful OFDM symbol) and a postfix (inserted at the end of the previous OFDM symbol). inter-carrier frequency / sub-carrier separation: frequency separation between OFDM sub-carriers, defined as the OFDM sampling frequen
33、cy divided by the FFT size OFDM unit: group of constellation symbols to be mapped onto a sub-band, a subset of the OFDM carriers OFDM samples: discrete-time complex values generated at the output of the IFFT, which may be complemented by the insertion of additional complex values (such as samples fo
34、r pre/post fix and time windowing) NOTE: Additional digital signal processing (such as filtering) may be applied to the resulting samples, prior to being fed to a digital-to-analog converter. OFDM sampling frequency: total number of samples, including guard interval samples, transmitted during one O
35、FDM symbol interval, divided by the symbol period repeater: device (e.g. CGC) that receives, amplifies and transmits the radiated or conducted RF carrier both in the down-link direction (from the satellite to the mobile area) and in the up-link direction (from the mobile to the satellite) return lin
36、k: unidirectional radio link for the transmission of signals from a UE to a gateway via a satellite rice factor: power ratio between LOS component and diffuse component ETSI ETSI TR 102 443 V1.1.1 (2008-08) 8 spot: geographical are under beam coverage uplink: unidirectional radio link for the transm
37、ission of signals from a UE to a satellite useful OFDM symbol: time domain signal corresponding to the IFFT/FFT window, excluding the guard time useful OFDM symbol duration: time duration of the useful OFDM symbol 3.2 Symbols For the purposes of the present document, the following symbols apply: F0
38、OFDM sampling frequency FdMaximum Doppler shift. N Total number of IFFT/FFT bins (sub-carriers) NpNumber of prefix samples NuNumber of modulated sub-carriers (i.e. sub-carriers carrying information) TsOFDM symbol period TgOFDM prefix duration TuOFDM useful symbol duration f Sub-carrier separation 3.
39、3 Abbreviations For the purposes of the present document, the following abbreviations apply: ACI Adjacent Channel Interference APSK Amplitude and Phase Shift Keying AWGN Additive White Gaussian Noise BER Bit Error Rate C/N Carrier to Noise power ratio CGC Complementary Ground Component CRC Cyclic Re
40、dundancy Check CPICH Common Pilot Channel DC-RF Direct Current to Radio Frequency DL Down Link EIRP Effective Isotropic Radiated Power FDM Frequency Division Multiplexing FFS For Further Study FFT Fast Fourier Transform FIR Finite Impulse Response GEO Geostationary Earth Orbit GW GateWay HARQ Hybrid
41、 Automatic Repeat reQuest HPA High Power Amplifiers HSDPA High Speed Downlink Packet Access HS-DSCH High Speed - Downlink Shared CHannel IBO Input Back-Off IFFT Inverse Fast Fourier Transform IMR Intermediate Module RepeaterISI Inter Symbol Interference LOS Line-Of-Sight LTWTA Linearized Travelling
42、Wave Tube Amplifier LUT Look-Up Table MAC Medium Access Control MIMO Multiple Input Multiple Output NL Non Linear NLOS No Line-Of-Sight OBO Output Back Off ETSI ETSI TR 102 443 V1.1.1 (2008-08) 9 OFDM Orthogonal Frequency Division Multiplexing PAPR Peak-to-Average Power Ratio PDSCH Physical Downlink
43、 Shared CHannel PER Packet Error Rate PhCh Physical ChannelPSK Phase Shift Keying QAM Quadrature Amplitude Modulation SCCH Shared Control CHannel S-DMB Satellite-Digital Mobile Broadcasting SFN Single Frequency Network SNR Signal-to-Noise Ratio T-F Time-Frequency TPCCH Transmit Power Control CHannel
44、 TTI Transmission Time Interval TWTA Travelling Wave Tube Amplifier UE User Equipment UTRAN UMTS Terrestrial Radio Access Network WCDMA Wideband Code Division Multiple Access 4 OFDM technology and background 4.1 OFDM Fundamentals 4.1.1 OFDM Definitions The technique of Orthogonal Frequency Division
45、Multiplexing (OFDM) is based on the well-known technique of Frequency Division Multiplexing (FDM). In FDM different streams of information are mapped onto separate parallel frequency channels. Each FDM channel is separated from the others by a frequency guard band to reduce interference between adja
46、cent channels. The OFDM technique differs from traditional FDM in the following interrelated ways: 1) multiple carrier multiple carriers (called sub-carriers) carry the information stream; 2) the sub-carriers are orthogonal to each other; and 3) a guard time may be added to each symbol to combat the
47、 channel delay spread and inter-symbol interference induced by linear distortion. These concepts are illustrated in the time-frequency representation of OFDM presented in figure 1. Sub-carriersFFTTimeSymbols5 MHz BandwidthGuard IntervalsFrequencyFigure 1: Frequency-Time representation of an OFDM Sig
48、nal Since the orthogonality is guaranteed between overlapping sub-carriers and between consecutive OFDM symbols in the presence of time/frequency dispersive channels the data symbol density in the time-frequency plane can be maximized. ETSI ETSI TR 102 443 V1.1.1 (2008-08) 104.1.2 OFDM Signal Genera
49、tion Data symbols are synchronously and independently transmitted over a high number of closely spaced orthogonal sub-carriers using linear modulation (either PSK, APSK or QAM). The generation of the QAM/OFDM signal can be conceptually illustrated as in figure 2, where nis the nthsub-carrier frequency (in rad/s) and 1/Tuis the QAM symbol rate. Note that the sub-carriers frequencies are equally spaced and hence the sub-carrier separation is constant. That is: 1,1,21=Nnfnn. In practice, the OFDM signal can be generated u
