1、 Rec. ITU-R S.1149-2 1 RECOMMENDATION ITU-R S.1149-2 Network architecture and equipment functional aspects of digital satellite systems in the fixed-satellite service forming part of synchronous digital hierarchy transport networks (Question ITU-R 201/4) (1995-1997-2005) Scope This Recommendation ad
2、dresses network architecture and equipment functions relevant for the design of synchronous digital satellite systems in the FSS forming parts of, or providing syhcronous interconnections between, transport networks based on the SDH. A general architectural diagram of FSS systems with SDH network tr
3、ansport capability is introduced. The basic requirement is transparent transport of SDH signal elements (referred to as virtual containers) through the satellite system. This Recommendation focuses on SDH functionalities in the satellite system synchronous baseband equipment (SBE) necessary to reali
4、ze three different scenarios for satellite system integration in SDH transport networks. The ITU Radiocommunication Assembly, considering a) that digital satellite systems of the FSS are constituent elements of public/private networks in which synchronous digital hierarchy (SDH)-based transmission t
5、echnologies are deployed; b) that ITU-T Recommendations G.707 and G.708 specify the network node interfaces (NNIs) for the SDH transport systems and reference all the other SDH Recommendations in ITU-T; c) that ITU-T Recommendations G.803 and G.805 define the architecture of SDH transport systems in
6、 way that is independent of the transmission technology; d) that ITU-T Recommendation G.780 defines the terminology of SDH and that ITU-T Recommendation G.783 specifies the characteristics of SDH functional blocks; e) that ITU-T Recommendations G.702, G.703, G.704 and G.957 define the bit rates, the
7、 synchronous frame structures and the physical parameters of the electrical and optical interfaces of SDH systems; f) that SDH timing requirements are covered in ITU-T Recommendations G.781, G.813, G.822 and G.825; g) that ITU-T Recommendations G.831, G.784, G.773 and G.774 define the management cap
8、abilities of SDH, the management functions, the protocols, interfaces and the management information model from the network element viewpoint; h) that integration with the telecommunications management network (TMN), defined in ITU-T Recommendation M.3000 Overview of TMN Recommendations, is supporte
9、d by these management recommendations and that the TMN Recommendations for SDH satellite systems are Recommendations ITU-R S.1250, ITU-R S.1251 and ITU-R S.1252; 2 Rec. ITU-R S.1149-2 j) that the performance of hypothetical reference digital paths (HRDPs) through SDH systems is defined in ITU-T Reco
10、mmendations G.826 and G.828. With the corresponding ITU-R Recommendations being ITU-R S.1062 and ITU-R S.1521; k) that the availability requirements for all transport systems are given in ITU-T Recommendation G.827 and the corresponding ITU-R Recommendations are ITU-R S.579 and ITU-R S.1522; l) prot
11、ection switching architectures are described in ITU-T Recommendations G.841 and G.842; m) that ITU-T Recommendation G.861 Radio and satellite SDH integration guidelines, describes the principles and guidelines for the integration of satellite and radio systems in SDH transport networks, including th
12、e concept of point-to-multipoint topologies; n) that the inherent multidestination and multipoint capabilities of satellite systems provide significant operational advantages; o) that Recommendations ITU-R F.750 and ITU-R F.751 define architectures, functional aspects, and transmission characteristi
13、cs and performance of radio-relay systems in SDH-based networks; p) that ITU-T Recommendation G.832 defines the method of transporting PDH elements over SDH systems but that interconnection and interworking between PDH and SDH networks may be handled differently within a satellite system providing t
14、hat the external interfaces and functionalities are compatible with terrestrial systems; q) that there are ongoing studies in ITU-R on transmission systems, their performance, multiple access methods and operation and maintenance (OAM) aspects, recommends 1 that digital satellite systems in the FSS
15、comply with the network architecture and equipment functional requirements described in this Recommendation to support their integration into SDH transport systems. Rec. ITU-R S.1149-2 3 CONTENTS Page 1 Introduction 5 1.1 Scope. 5 1.2 Abbreviations 6 1.3 Definition of satellite specific terms. 8 2 S
16、DH transport network description 9 2.1 SDH multiplexing techniques. 9 2.1.1 Basic structure 9 2.1.2 Sub-STM-1 multiplex signals for radio systems 10 2.2 Layered network modelling 12 2.2.1 ATM supported on SDH layer networks 12 3 Applications of the FSS in SDH transport networks 15 3.1 Service aspect
17、s 15 3.2 Network management aspects 15 3.2.1 General 15 3.2.2 SDH equipment and management functional blocks 16 3.3 FSS system operational aspects 18 3.3.1 Multiplexing flexibility and efficiency. 18 3.3.2 Timing. 18 4 FSS-SDH network scenarios, modelling and description 19 4.1 Digital sections (sce
18、nario 1) . 19 4.1.1 Description 19 4.1.2 Layered network model 19 4.2 Wide-area single-rate cross-connect (scenario 2). 20 4.2.1 Description 20 4.2.2 Layered network model 21 4.3 Wide-area multi-rate cross-connect (scenario 3) 22 4.3.1 Description 22 4.3.2 Layered network model 22 4 Rec. ITU-R S.114
19、9-2 Page 5 FSS-SDH synchronous baseband equipment . 23 5.1 SBE for SDH digital section (scenario 1). 23 5.1.1 Digital section at 155.52 Mbit/s (STM-1) 23 5.1.2 PDH embedded transmission of SDH signals 24 5.1.3 Satellite digital section at 51.84 Mbit/s (STM-0) . 24 5.1.4 AU pointer processing and Dop
20、pler buffers. 24 5.1.5 Alarm conditions and consequent actions 25 5.2 SBE for wide-area single-rate cross-connect (scenario 2) 26 5.2.1 SSOH functions including multidestination for S-IOs . 27 5.2.2 Section layer frame format and multiplex structure . 29 5.2.3 AU pointer processing and Doppler buffe
21、rs. 29 5.2.4 Alarm conditions and consequent actions 29 5.3 SBE for wide-area multi-rate cross-connect (scenario 3). 30 5.3.1 SSOH functions including multidestination for satellite intra-office sections . 32 5.3.2 Satellite tributary unit groups 1/2 multiplex structures 34 5.3.3 Satellite section l
22、ayer frame structures . 35 5.3.4 SSOH allocation . 36 5.3.5 Control channel mechanism . 37 5.3.6 Section bit rates. 39 5.3.7 Pointer processing and Doppler buffers . 39 5.3.8 TU pointer byte interleaving. 40 5.3.9 Alarm conditions and consequent actions 40 Annex 1 SSOH DCC serial channel protocol .
23、41 Rec. ITU-R S.1149-2 5 1 Introduction 1.1 Scope This Recommendation addresses network architecture and equipment functions relevant for the design of synchronous digital satellite systems in the FSS forming parts of, or providing synchronous interconnections between, transport networks based on th
24、e SDH. A general architectural diagram of FSS systems with SDH network transport capability is shown in Fig. 1. The basic requirement is transparent transport of SDH signal elements (referred to as virtual containers) through the satellite system. This Recommendation focuses on SDH functionalities i
25、n the satellite system synchronous baseband equipment (SBE) necessary to realize three different scenarios for satellite system integration in SDH transport networks: Scenario 1: SDH multiplex section Scenario 2: wide-area single-rate cross-connect (common internal section bit rate of 51.84 Mbit/s)
26、Scenario 3: wide-area multi-rate cross-connect (a range of internal section bit rates 51.84 Mbit/s) This Recommendation follows the “ITU-T Recommendation G.861 radio and satellite SDH integration guidelines”. 6 Rec. ITU-R S.1149-2 NOTE 1 Synchornous baseband equipment and satellite transmission equi
27、pment are illlustrated as separate units for the purpose of explanation; they may be implemented physically as one unit. NOTE 2 Reference point A: open EI for scenario 1; NNI and NNRP for scenarios 2 and 3. NOTE 3 Reference point B: SRP and open SEI for scenarios 1 and 2, SRP and closed SEI for scen
28、ario 3 (see the “ITU-T Recommendation G.861 radio and satellite SDH integration guidelines”). The basic functions of the SBE are one or more of the following, depending on the scenario: perform SDH multiplex set of functions, adapted to satellite applications and dependent on scenario; conversion an
29、d adaptation of section and path layers to satellite system internal interfaces or reference points; establishment of section and possibly path layer asymmetrical multidestination connections, and support point-to-point symmetrical path layer cross-connected connections; perform specific section fun
30、ctions for signal transmission over the satellite medium; integration of SDH pointer and satellite system timing; SBE SDH multiplex based management functions. The basic functions of the satellite transmission equipment are: modem functions; multiple access system protocols, procedures and their man
31、agement functions; timing preservation. 1.2 Abbreviations AIS: alarm indication signal APS: automatic protection switching AU: administrative unit AUG: administrative unit group BIP: bit interleaved parity DCC: data communication channel DXC: digital cross connect EI: equipment interface FDMA: frequ
32、ency division multiple access HOVC: higher order virtual container HPA: higher order path adaptation HPC: higher order path connection HPOM: higher order path overhead monitor HPT: higher order path termination HSPA: higher order satellite path adaptation HSPT: higher order satellite path terminatio
33、n HSSA: higher order satellite section adaptation HSUG: higher order supervisory unequipped generator Rec. ITU-R S.1149-2 7 HSUM: higher order supervisory unequipped monitor IOS: intra-office section ISI: internal satellite interface LOVC: lower order virtual container LPA: lower order path adaptati
34、on LPC: lower order path connection LPOM: lower order path overhead monitor LPT: lower order path termination LSSA: lower order satellite section adaptation LSUG: lower order supervisory unequipped generator LSUM: lower order supervisory unequipped monitor LT: line termination MCF: message communica
35、tions function MDSS: multi-destination satellite server MSA: multiplex section adaptation MSOH: multiplex section overhead MSP: multiplex section protection MST: multiplex section termination NNI: network node interface NNRP: network node reference point OAM: operation, administration and maintenanc
36、e OHA: overhead access PDH: plesiochronous digital hierarchy POH: path overhead RDI: remote defect indication REI: remote error indication RSOH: regenerator section overhead RST: regenerator section termination SBE: synchronous baseband equipment SDH: synchronous digital hierarchy SEI: satellite equ
37、ipment interface SETPI: synchronous equipment timing physical interface SETS: synchronous equipment timing source S-IOS: satellite intra-office section SOH: section overhead 8 Rec. ITU-R S.1149-2 SPI: synchronous physical interface SRP: satellite reference point SRT: satellite regenerator terminatio
38、n SSOH: satellite section overhead SSPI: synchronous satellite physical interface SST: satellite section termination SSTM-n: satellite synchronous transport module-n STM-N: synchronous transport module-N STUG-ij: satellite tributary unit group ij TDMA: time division multiple access TMN: telecommunic
39、ation management network TU: tributary unit TUG: tributary unit group VC: virtual container VOW: voice order wire 1.3 Definition of satellite specific terms HSPA: higher order satellite path adaptation a higher order adaptation function within the satellite system synchronous baseband equipment. HSP
40、T: higher order satellite path termination a higher order path termination function within the satellite system synchronous baseband equipment. HSSA: higher order satellite section adaptation a higher order section adaptation function within the satellite system synchronous baseband equipment. ISI:
41、internal system interface a system specific internal interface which is not subject to standardization. LSP: lower order satellite path a lower order path through the satellite system. LSSA: lower order satellite section adaptation a lower order section adaptation function within the satellite syste
42、m synchronous baseband equipment. MDSS: multidestination satellite server layer the layer in the model which represents the multidestination capability of the satellite transmission system. SFCOH: satellite frame complementary overhead an overhead to the baseband composite signal to accommodate sate
43、llite transmission systems OAM functions (e.g. modem alarms and VOW). S-IOS: satellite intra office section an SDH section which is internal to the satellite system and which may have multipoint topology. It may cover a wide geographical area. SLT: satellite line terminal performs normal RST, MST an
44、d MS APS functions on the satellite side of the NNI. SRP: satellite reference point the point between the synchronous baseband equipment and the satellite transmission equipment. Rec. ITU-R S.1149-2 9 SSOH: satellite section overhead the overhead used within the satellite section between the synchro
45、nous baseband equipment. SSPI: satellite synchronous physical interface the physical interface between the synchronous baseband equipment and the satellite transmission equipment. SST: satellite section termination the function where the section overhead may be manipulated. SS-TDMA: satellite switch
46、ed time-division multiple access a fixed TDMA system with on-board burst-to-burst cyclic inter-beam connection reconfigurations. SSTM-n: satellite synchronous transport module order n similar to STM-n of terrestrial transport systems but consisting of STUG payload multiplex and satellite section spe
47、cific overhead. STUG-ij: satellite tributary unit group ij similar to a terrestrial tributary unit group TUG but represents a new multiplexing stage in between the G.708 TUG-2 level and TUG-3/VC-3 level. 2 SDH transport network description 2.1 SDH multiplexing techniques 2.1.1 Basic structure The ba
48、sic SDH multiplexing techniques (bit rates, frame formats and structures) are described in ITU-T Recommendation G.707. The SDH multiplex hierarchy has a level 1 bit rate of 155.52 Mbit/s (STM-1) with several higher and some lower bit rates. The bit rates listed in Table 1 constitute the current SDH
49、but higher speeds may be added in the future: TABLE 1 SDH hierarchical bit rates Identity SDH level Hierarchical bit rate (kbit/s) STM-0 0 51 840 STM-1 1 155 520 STM-4 4 622 080 STM-16 16 2 488 320 STM-64 64 9 953 280 STM-256 256 39 813 120 NOTE The specification of levels higher than 256 requires further study. Figure 2 shows the basic 125 s frame structure of the STM-1 signal in a 270 9 bytes matrix format. This SDH element is referred to as a virtual container (VC). 10 Rec. ITU-R S.1149-2 1149-021931459FIGURE 2STM-1 (155.
