1、 TIA STANDARD Regenerative Satellite Mesh-A (RSM-A) Air Interface - Physical Layer Specification - Part 7: Synchronization TIA-1040.1.07 May 2006TELECOMMUNICATIONS INDUSTRY ASSOCIATION The Telecommunications Industry Association represents the communications sector of NOTICE OF COPYRIGHT This docume
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17、rty Rights4 Foreword 4 1 Scope5 2 References 5 3 Definitions and abbreviations.5 3.1 Definitions. 5 3.2 Abbreviations 5 4 General description of synchronization system6 4.1 System timing structure 8 4.2 General requirement 8 4.2.1 Timing and frequency reference point 8 4.2.2 ST requirement 8 4.2.3 N
18、etwork requirement. 8 4.2.4 Measurement conditions . 8 5 Timing synchronization9 5.1 Introduction . 9 5.2 Frequency accuracy and stability 9 5.2.1 ST Frequency accuracy and stability 9 5.3 Timing error 9 5.3.1 Initial ST timing error . 9 5.3.2 ST Timing error. 9 5.4 Time of Day information 9 5.4.1 T
19、oD definition . 9 5.4.2 ToD format 10 5.4.3 UTC time. 11 5.5 Beacon transmission (Satellite to ST direction). 11 5.5.1 Superframe 11 5.5.2 Frame alignment 11 5.5.3 Beacon burst structure. 12 5.5.3.1 Beam settling bit pattern 13 5.5.3.2 Unique Word bit pattern 14 5.5.3.3 PN sequence bit pattern. 14 5
20、.6 Early/Late timing measurement field . 15 5.7 Initial timing acquisition. 15 5.8 Timing synchronization maintenance. 15 6 Frequency synchronization 16 6.1 Calculate the Initial Doppler value. 16 Annex A (normative): Timing calculations17 A.1 General description 17 A.1.1 Calculation of Path Length
21、. 17 A.1.2 GPS accuracy 17 A.2 Calculate the timing offset .17 Annex B (informative): Bibliography.18 History 19 TIA 1040.1.07 2Intellectual Property Rights IPRs essential or potentially essential to the present document may have been declared to ETSI. The information pertaining to these essential I
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24、 server) which are, or may be, or may become, essential to the present document. Satellite Earth Stations and Systems (SES); Regenerative Satellite Mesh - A (RSM-A) air interface; Physical layer specification; Part 7: Synchronization Foreword This Technical Specification (TS) has been produced by ET
25、SI Technical Committee Satellite Earth Stations and Systems (SES). The present document is part 7 of a multi-part deliverable covering the BSM Regenerative Satellite Mesh - A (RSM-A) air interface; Physical layer specification, as identified below: Part 1: “General description“; Part 2: “Frame struc
26、ture“; Part 3: “Channel coding“; Part 4: “Modulation“; Part 5: “Radio transmission and reception“; Part 6: “Radio link control“; Part 7: “Synchronization“. TIA 1040.1.07 31 Scope The present document presents the requirements for synchronizing timing and frequency between the ST and the satellite ne
27、twork within the TC-SES BSM Regenerative Satellite Mesh - A (RSM-A) air interface family. 2 References The following documents contain provisions which, through reference in this text, constitute provisions of the present document. References are either specific (identified by date of publication an
28、d/or edition number or version number) or non-specific. For a specific reference, subsequent revisions do not apply. For a non-specific reference, the latest version applies. Referenced documents which are not found to be publicly available in the expected location might be found at http:/docbox.ets
29、i.org/Reference. 1 ETSI TS 102 189-2: “Satellite Earth Stations and Systems (SES); Regenerative Satellite Mesh - A (RSM-A) air interface; MAC/SLC layer specification; Part 2: MAC layer“. 2 IETF RFC 1305: “Network Time Protocol (Version 3) Specification, Implementation and Analysis“. 3 Definitions an
30、d abbreviations 3.1 Definitions For the purposes of the present document, the following terms and definitions apply: Network Operations Control Centre (NOCC): centre that controls the access of the satellite terminal to an IP network and also provides element management functions and control of the
31、address resolution and resource management functionality satellite payload: part of the satellite that provides air interface functions NOTE: The satellite payload operates as a packet switch that provides direct unicast and multicast communication between STs at the link layer. Satellite Terminal (
32、ST): terminal installed in the user premises terrestrial host: entity on which application level programs are running NOTE: It may be connected directly to the Satellite Terminal or through one or more networks. 3.2 Abbreviations For the purposes of the present document, the following abbreviations
33、apply: AWGN Additive White Gaussian Noise BPSK Binary Phase Shift Keying ECEF Earth Centred Earth Fixed IP Internet Protocol kbps kilo bits per second (thousands of bits per second) LHCP Left Hand Circular Polarization TIA 1040.1.07 4LLA Latitude, Longitude and Altitude LSB Least Significant Bit MIP
34、 Management Information Packet MMI Man Machine Interface NOCC Network Operations Control Centre PHY PHYsical PN Pseudo NoisePTP Point-to-Point QPSK Quaternary Phase Shift Keying RHCP Right Hand Circular Polarization RSM Regenerative Satellite Mesh SLC Satellite Link Control ST Satellite Terminal TDM
35、A Time Division Multiple Access TIP Transmission Information Packet ToD Time of Day ULPC UpLink Power Control UTC Universal Coordinated Time UW Unique Word 4 General description of synchronization system BSM RSM-A is a multi-spot beam, multicarrier, synchronous system where the timing and frequency
36、on the satellite serve as the reference to synchronize the TDMA transmissions for the STs, and other network elements. The satellite includes a packet switch designed to provide single-hop, point to point packet routing between downlink cells. The functions of the physical layer are different for th
37、e uplink and downlink. The major functions are illustrated in figure 4. The present document describes the synchronization functions - this group of functions is highlighted in figure 4. TIA 1040.1.07 5UPLINK DOWNLINK Part 3:Channel coding Part 2:Frame structure Part 4:Modulation Part 5:Radio transm
38、ission and reception Part 7:Synchronization Block interleaving Inner coding(convolutional)Downlink burst building Downlink modulation (QPSK) ST receiver ScramblingAssemble packets into code blocks Outer coding (Reed-Solomon)No interleavingInner coding(hamming)Uplink burst building Uplink modulation(
39、OQPSK) Part 6: Radio link controlScramblingAssemble packets into code blocks Outer coding (Reed-Solomon) Timing and frequency control ST transmitter Figure 4: Physical layer functions The timing synchronization requirements are described in clause 5, and the frequency synchronization requirements ar
40、e described in clause 6. Synchronization in the RSM-A system is composed of three major tasks: timing synchronization; frequency synchronization; frame synchronization; A master oscillator onboard the RSM-A spacecraft is the primary reference for all synchronization processes. The fundamental goal o
41、f synchronization is to have all STs operate such that all bursts arrive at the satellite synchronized in timing and frequency. TIA 1040.1.07 64.1 System timing structure The RSM-A satellite system is a TDMA system. Timing configuration in the system is composed of superframe, frame, timeslot, symbo
42、l and bit. One superframe equals to 768 ms, and is divided into eight uplink frames or 256 downlink frames. The downlink frame counter is called the Time of Day (ToD) counter. Each uplink frame has 32 timeslots. The uplink frame duration is 96 ms, one timeslot duration is 3 ms. Each symbol correspon
43、ds to 2 bits. The complete uplink and downlink frame structure is defined in BSM RSM-A Physical Layer Specification, TS 102 188-2. A superframe always starts from the first time slot in a frame that meets ToD mod 256 = 0. An Uplink frame always starts with time slot 0 when ToD mod 32 = 0. 4.2 Genera
44、l requirement 4.2.1 Timing and frequency reference point The satellite is selected to be the reference point for both timing and frequency. 4.2.2 ST requirement The ST timing and frequency requirements are: Both transmitter and receiver timing shall be derived from the same timebase. Both transmitte
45、r and receiver frequency shall be derived from the same frequency source. The ST shall use the same source for both RF frequency generation and the timebase generator. All return link signals (control and user data) transmitted from the STs shall achieve frame/timeslot alignment on the satellite tim
46、ing reference point, i.e. input of satellite antenna. In various operation modes, synchronization shall be maintained under the worst case timing and frequency drift rate due to ST-satellite relative motion and ST master oscillator stability. The ST oscillator short-term stability shall maintain all
47、 timing offset, frequency offset and symbol rate requirement specified in BSM RSM-A physical layer specification, TS 102 188-5. 4.2.3 Network requirement The Network timing and frequency requirements are: The network should make multiple rate and volume timeslot assignments on the same uplink freque
48、ncy or with the same carrier designator (see BSM RSM-A physical layer specification, TS 102 188-5) as far as possible. When assigning timeslots on different carrier designators the network shall provide at least 3 ms guard time for the ST to switch between the two different transmit frequencies. An
49、ST may ignore assignments which it cannot use. At ST initialization, the network shall be able to estimate the slotted aloha signal arrival to the accuracy better than 15 Hz 1-sigma in frequency, 2,6 s 1-sigma in timing, under the condition of AWGN channel. 4.2.4 Measurement conditions In the present document, all timing and frequency related parameters are defined under the condition of AWGN channel, when the Beacon is received at a C/No = 78 dB-Hz minimum. Unless specified otherwise, all timing and frequency related parameters are defined as 1-sigma v
