1、 Rec. ITU-R F.750-4 1 RECOMMENDATION ITU-R F.750-4*ARCHITECTURES AND FUNCTIONAL ASPECTS OF RADIO-RELAY SYSTEMS FOR SYNCHRONOUS DIGITAL HIERARCHY (SDH)-BASED NETWORKS (Questions ITU-R 160/9 and ITU-R 211/9) (1992-1994-1995-1997-2000) Rec. ITU-R F.750-4 The ITU Radiocommunication Assembly, considering
2、 a) that ITU-T Recommendation G.707 specifies the bit rates, the multiplexing structure and the detailed mappings associated with the synchronous digital hierarchy (SDH); b) that ITU-T Recommendation G.783 specifies the general characteristics and functions of synchronous multiplexing equipment and
3、ITU-T Recommendation G.784 specifies the management of SDH equipment and networks; c) that ITU-T Recommendations G.703 and G.957 specify the physical parameters of the electrical and optical interfaces of SDH equipment; d) that ITU-T Recommendations G.803 and G.831 specify the architectures and mana
4、gement capabilities of transport networks based on the SDH; e) that among the family of SDH equipment there will be synchronous digital radio-relay systems (SDH-DRRs); f) that there is a need to ensure a complete operational integration of the SDH-DRRs in a synchronous network; g) that Recommendatio
5、n ITU-R F.751 specifies transmission characteristics and performance requirements of SDH digital radio-relay systems, recommends 1 that digital radio-relay systems for the synchronous digital hierarchy should comply with the requirements described in Annex 1. ANNEX 1 Contents 1 Introduction 1.1 Scop
6、e 1.2 Abbreviations 1.3 Definitions 2 Features and layering of the SDH-based networks 2.1 SDH description 2.2 SDH layering 2.2.1 Layering 2.2.2 Layering and the SDH frame structure 2.3 Network node interfaces (NNI) 2.4 Functional blocks of SDH equipment _ *This Recommendation should be brought to th
7、e attention of Radiocommunication Study Group 4 (Working Party 4B) and Telecommunication Standardization Study Groups 13 and 15. 2 Rec. ITU-R F.750-4 3 Application of radio-relay systems to SDH-based networks 3.1 General considerations 3.1.1 Interfaces 3.1.2 Mid-air interconnectivity 3.2 Multiplex a
8、nd regenerator sections 3.3 Functional block diagrams of STM-N digital radio-relay systems 3.3.1 SDH radio synchronous physical interface function (RSPI) 3.3.1.1 Signal flow from B to R 3.3.1.2 Signal flow from R to B 3.3.1.3 Application to the transmission of N times STM-N 3.3.2 Radio protection sw
9、itching (RPS) 3.3.2.1 Signal flow 3.3.2.2 Additional functionality on the signal flow from XT (tributary side) to XL (line side) 3.3.2.3 Additional functionality on the signal flow from XL (line side) to XT (tributary side) 3.3.2.4 Switching initiation criteria 3.3.2.5 Switching performance 3.3.2.6
10、Switch restore 3.3.3 ROHA (Radio OverHead Access) 3.4 Radio terminals and repeaters arrangement of STM-N DRRS 3.4.1 Radio repeater arrangement 3.4.2 Radio protection switching (RPS) and radio terminals arrangement 3.5 Synchronization 4 Function and usage of section overhead (SOH) bytes 4.1 Multiplex
11、 and regenerator section overheads (SOH) 4.2 Media-specific bytes 4.3 Reduced SOH functionality for intra-station sections 5 Radio-relay specific functions 6 STM-0 transmission rate SDH radio-relay systems 6.1 Network interfaces 6.2 Multiplexing schemes 6.3 Multiplex and regenerator radio sections 6
12、.4 Functional block diagrams of STM-0 digital radio-relay systems 6.4.1 Radio-relay STM-0 synchronous physical interface (RR-RSPI) function 6.4.2 Radio-relay STM-0 regenerator section termination (RR-RST) 6.4.3 Radio-relay STM-0 multiplex section termination (RR-MST) 6.4.4 Radio-relay STM-0 multiple
13、x section adaptation (RR-MSA) 6.4.5 STM-0 radio-relay synchronous physical and equipment interface (RR-SPI and RR-EI) 6.5 Radio protection switching 6.6 Section overhead (SOH) for STM-0 DRRS 6.7 Techniques for transport of media-specific functions 7 Operation and maintenance aspects 7.1 Management f
14、unctions 7.2 Maintenance functions 7.2.1 RSPI and RR-RSPI maintenance functions 7.2.2 RPS maintenance functions 7.2.3 ROHA maintenance functions 7.2.4 Performance monitoring functions Appendix 1 RR-EI electrical characteristics Appendix 2 Migration strategy from an existing PDH to SDH-based networks
15、 Rec. ITU-R F.750-4 3 Appendix 3 Examples of practical implementations of the RPS function Appendix 4 Transmission of media-specific functions of STM-0 DRRS through radio complementary section overhead (RCSOH) Appendix 5 Additional primitives for operation and maintenance purpose of RSPI/RR-RSPI, RP
16、S and ROHA functional blocks Appendix 6 Performance event for RSPI, RPS and ROHA functional blocks 1 Introduction 1.1 Scope This Annex defines the architectures and functional aspects of the SDH-DRRS aiming at their complete operational integration in a SDH-based network. The architectures are defin
17、ed in terms of functional blocks without any constraint on physical implementation. 1.2 Abbreviations ADM Add/drop multiplexer ATM Asynchronous transfer mode ATPC Automatic transmitter power control AU Administrative unit AUG Administrative unit group BIP Bit interleaved parity C Container DCC Data
18、communication channel DRRS Digital radio-relay system DXC Digital cross-connect ECC Embedded communication channel FEC Forward error correction EW Early warning FOTS Fibre optics transmission system HO Higher order path HOVC Higher order virtual container HPA Higher order path adaptation HPC Higher
19、order path connection HPT Higher order path termination IOS Intra-office section IOST Intra-office section termination ISI Intra-station interface LOF Loss of frame LOP Loss of pointer LOS Loss of signal LOVC Lower order virtual container 4 Rec. ITU-R F.750-4 LPA Lower order path adaptation LPC Lowe
20、r order path connection LPT Lower order path termination MAF Management application function MCF Message communications function MS Multiplex section MSA Multiplex section adaptation MSOH Multiplex section overhead MSP Multiplex section protection MST Multiplex section termination MUX Multiplexer NE
21、 Network element NEF Network element function NNI Network node interface OAM Operation, administration and maintenance OH Overhead OHA Overhead access OLI Optical line interface OLT Optical line termination OR Optical repeater OSF/MF Operation system function/Mediation function PDH Plesiochronous di
22、gital hierarchy POH Path overhead PPI Plesiochronous physical interface RCSOH Radio complementary section overhead RF Radio frequency RFCOH Radio frame complementary overhead ROHA Radio overhead access RPI Radio physical interface (generic) RPPI Radio plesiochronous physical interface RPS Radio prot
23、ection switching RR-EI Radio-relay equipment interface RR-MSA Multiplex section adaptation for STM-0 radio-relay RR-MST Multiplex section termination for STM-0 radio-relay RRR Radio-relay regenerator RR-RP Radio-relay reference point for STM-0 radio-relay RR-RSPI Radio STM-0 synchronous physical int
24、erface Rec. ITU-R F.750-4 5 RR-RST Regenerator section termination for STM-0 radio-relay RR-SPI Synchronous physical interface for STM-0 radio-relay RRT Radio-relay terminal RS Regenerator section RSOH Regenerator section overhead RSPI Radio synchronous physical interface RST Regenerator section ter
25、mination SDH Synchronous digital hierarchy SEMF Synchronous equipment management function SETPI Synchronous equipment timing interface SETS Synchronous equipment timing source SMN Synchronous management network SMS SDH management sub-network SOH Section overhead SPI SDH physical interface STM-N Sync
26、hronous transport module of order N STM-0 Synchronous transport module of order 0 equivalent to a transport of one AU-3 as defined by ITU-T Recommendation G.861 and frame structure at 51.84 Mbit/s defined by ITU-T Recommendation G.707. Defined also as RR-STM in previous versions of this Recommendati
27、on ITU-R F.750. TMN Telecommunications management network T, T Baseband access points TU Tributary unit TUG Tributary unit group VC Virtual container 1.3 Definitions The following definitions are relevant in the context of SDH-related Recommendations. Add/drop multiplexer (ADM) They provide the abil
28、ity to access any of the constituent signals within a STM-N signal without demultiplexing and terminating the complete signal. The interface provided for the accessed signal could be either according to ITU-T Recommendation G.703 or an STM-m (m n). Asynchronous transfer mode (ATM) See ITU-T Recommen
29、dations I.150, I.311, I.321 and I.327. Administrative unit (AU) An AU is the information structure which provides adaptation between the higher order path layer and the multiplex section layer (see ITU-T Recommendation G.707 for details). Administrative unit group (AUG) An AUG consists of a homogene
30、ous, byte interleaved assembly of AU-3s or AU-4s. 6 Rec. ITU-R F.750-4 Atomic function A function which if divided into simpler functions would cease to be uniquely defined for digital transmission hierarchies. It is therefore indivisible from a network point of view. The atomic functions for SDH eq
31、uipments are defined in each network layer by ITU-T Recommendation G.783. Bit interleaved parity (BIP) BIP-X is a code defined as a method of error monitoring (see ITU-T Recommendation G.707 for details). Container (C) A container is the information structure which forms the network synchronous info
32、rmation payload for a VC (see ITU-T Recommendation G.707 for details). Data communication channel (DCC) See ITU-T Recommendation G.783. Digital cross-connect (DXC) See ITU-T Recommendation G.783. Embedded communication channel (ECC) See ITU-T Recommendation G.783. Higher order path (HO) In a SDH net
33、work, the higher order path layers provide a server network from the lower order path layers (see ITU-T Recommendation G.783). Higher order virtual container (HOVC): VC-n (n = 3, 4) This element comprises either a single C-n (n = 3, 4) or an assembly of TUGs (TUG-2s or TUG-3s), together with the VC
34、POH appropriate to that level. Higher order path adaptation (HPA) The HPA function adapts a lower order VC (VC-1/2/3) to a higher order VC (VC-3/4) by processing the TU pointer which indicates the phase of the VC-1/2/3 POH relative to the VC-3/4 POH and assembling/disassembling the complete VC-3/4 (
35、see ITU-T Recommendation G.783). Higher order path connection (HPC) The HPC function provides for flexible assignment of higher order VCs (VC-3/4) within an STM-N signal (see ITU-T Recommendation G.783). Higher order path termination (HPT) The HPT function terminates a higher order path by generatin
36、g and adding the appropriate VC POH to the relevant container at the path source and removing the VC POH and reading it at the path sink (see ITU-T Recommendation G.783). Hitless switch A switch event between a working and a protection channel which does not add any errors to those already produced
37、by the propagation medium during the switching procedure. Inter-office section See ITU-T Recommendation G.958. Intra-office section (IOS) See ITU-T Recommendations G.957 and G.958 and 3.1. Rec. ITU-R F.750-4 7 Intra-office section termination (IOST) See ITU-T Recommendation G.958 and 3.1. Intra-stat
38、ion interface (ISI) Interface with reduced SOH functionality. See ITU-T Recommendation G.707. Lower order virtual container (LOVC): VC-n (n = 1, 2) This element comprises a single C-n (n = 1, 2) plus the lower order VC POH appropriate to that level. Lower order path adaptation (LPA) The LPA function
39、 adapts a PDH signal to an SDH network by mapping/de-mapping the signal into/out of a synchronous container. If the signal is asynchronous, the mapping process will include bit level justification. Lower order path connection (LPC) The LPC function provides for flexible assignment of lower order VCs
40、 in a higher order VC. Lower order path termination (LPT) The LPT function terminates a lower order path by generating and adding the appropriate VC POH to the relevant container at the path source and removing the VC POH and reading it at the path sink. Management application function (MAF) This is
41、 the origination and termination of TMN messages. See ITU-T Recommendation G.784. Message communications function (MCF) See ITU-T Recommendation G.783. Multiplex section adaptation (MSA) The MSA function processes the AU-3/4 pointer to indicate the phase of the VC-3/4 POH relative to the STM-N SOH a
42、nd byte multiplexes the AU groups to construct the complete STM-N frame (see ITU-T Recommendation G.783). Multiplex section overhead (MSOH) MSOH comprises rows 5 to 9 of the SOH of the STM-N signal. Multiplex section protection (MSP) The MSP function provides the capability of branching the signal o
43、nto another line system for protection purposes (see ITU-T Recommendation G.783). Multiplex section termination (MST) The MST function generates and adds rows 5 to 9 of the SOH (see ITU-T Recommendation G.783). Network element (NE) This is an element of the SMS. See ITU-T Recommendation G.784. Netwo
44、rk element function (NEF) See ITU-T Recommendation G.784. Network node interface (NNI) See ITU-T Recommendation G.707 and 2.3. 8 Rec. ITU-R F.750-4 Operation, administration and maintenance (OAM) See ITU-T Recommendation G.784. Overhead access (OHA) The OHA function gives external interfaces to stan
45、dardized SOH signals (see ITU-T Recommendation G.783). Optical line interface (OLI) See ITU-T Recommendation G.957. Optical line termination (OLT) See ITU-T Recommendation G.958. Operation system function/mediation function (OSF/MF) See ITU-T Recommendation G.784. Path overhead (POH) The VC POH prov
46、ides for integrity of communication between the points of assembly of a VC and its point of disassembly. Plesiochronous digital hierarchy (PDH) See ITU-T Recommendations G.702 and G.703. Radio complementary section overhead (RCSOH) The transmission, in STM-0 DRRS, as a well identified case of RFCOH,
47、 of a capacity equivalent to the six missed columns of a full STM-1 SOH format (see 6.6 and 6.7 and Recommendation ITU-R F.751). Radio frame complementary overhead (RFCOH) The transmission capacity contained in the radio frame (see 4.4 and 6.7 and Recommendation ITU-R F.751). Radio overhead access (
48、ROHA) The ROHA function gives external interfaces to radio specific SOH or RFCOH signals and gives suitable handling for the radio specific internal communication channels (see 3.3.3 and 7.2.3). Radio physical interface (RPI) Generic terminology for the typical radio-relay functions, including modul
49、ator, demodulator, transmitter, receiver, possible radio-framer, etc. (see 6.4). Radio plesiochronous physical interface (RPPI) A common description for the typical plesiochronous radio-relay functions, including modulator, demodulator, transmitter, receiver, possible radio-framer, etc. (see 6.4). Radio protection switching (RPS) See 3.3.2. Radio-relay equipment interface (RR-EI) for STM-0 radio-relay See Appendix 1. Multiplex section adaptation for STM-0 radio-relay (RR-MSA) See 6.4. Rec. ITU-R F.750-4 9 Multiplex section termination for STM-0 ra
