1、 Rec. ITU-R F.1668-1 1 RECOMMENDATION ITU-R F.1668-1 Error performance objectives for real digital fixed wireless links used in 27 500 km hypothetical reference paths and connections (Question ITU-R 210/9) (2004-2007) Scope This Recommendation provides updated information on error-performance object
2、ives for real digital fixed wireless links used in 27 500 km hypothetical reference paths and connections. It is the only Recommendation defining error-performance objectives for all real digital fixed wireless links. Performance events and objectives for connections using equipment designed prior t
3、o approval of ITU-T Recommendation G.826 in December 2002 are given in ITU-T Recommendation G.821 and Recommendations ITU-R F.634, ITU-R F.696 and ITU-R F.697. Recommendations ITU-R F.1397 and ITU-R F.1491 are superseded by this Recommendation. Example of a connection, path, link and hop are given i
4、n Annex 1. Definitions of the error performance events, derived from ITU-T Recommendations G.826 and G.828, are given in Annex 2. Examples of calculations of the error performance parameters are given in Annex 3. The ITU Radiocommunication Assembly, considering a) that ITU-T has specified the error
5、performance parameters and objectives for international constant bit rate (CBR) digital paths and connections in ITU-T Recommendation G.8261, and for international CBR synchronous digital paths in ITU-T Recommendation G.8282; b) that ITU-T has specified the error performance events and the block str
6、uctures for synchronous digital hierarchy (SDH) multiplex and regenerator sections in ITU-T Recommendation G.829; c) that any real path link for digital data transmission may be realized using a linear and/or redundant topology, depending on the needs of network providers; d) that there is a need to
7、 establish the performance objectives for real digital radio links in order to allow proper engineering of the fixed wireless links; 1It is not required to apply this Recommendation to connections which operate below the primary rate using equipment designed prior to the approval (December 2002) of
8、ITU-T Recommendation G.826 End-to-end error performance parameters and objectives for international constant bit rate digital paths and connections. 2ITU-T Recommendation G.826 deals with performance of PDH paths and of those SDH paths using equipment designed prior to the approval of ITU-T Recommen
9、dation G.828 in March 2000. ITU-T Recommendation G.828 deals with performance of SDH paths using equipment designed as of or after the adoption of ITU-T Recommendation G.828 in March 2000. 2 Rec. ITU-R F.1668-1 e) that for the purpose of this Recommendation, the national portion of a 27 500 km hypot
10、hetical reference path (HRPs) or hypothetical reference connection (HRCs) can be subdivided into three basic sections (see Fig. 1), recommends 1 that the error performance objectives (EPOs) applicable to each direction of any real fixed wireless link of length Llinkused in the international portions
11、 of a 27 500 km HRP and HRC can be derived by means of equation (1) and using the values in Tables 1a and 1b for SDH systems designed according to ITU-T Recommendation G.828 and values in Tables 2a and 2b for systems designed according to ITU-T Recommendation G.826. The lower limit of Llinkused to s
12、cale the objectives to the real case is Lmin = 50 km. jRlinkjCLLBEPO += )/( (1) where: j = 1 for Lmin Llink 1 000 km for intermediate country j = 2 for 1 000 km 5-15 2.5 103(1 + BR) 0 2.5 1031 103 BRESR 15-55 3.75 103(1 + BR) 0 3.75 1031.5 103 BRESR 55-160 8 103(1 + BR) 0 8 1033.2 103 BRESR 160-400
13、Not applicable Not applicable Not applicable Not applicable SESR 400 1 104(1 + BR) 0 1 1044 105 BRBBER 1.5-400 1 105(1 + BR) 0 1 1054 106 BRTABLE 2b Parameters for the EPO for terminating countries according to ITU-T Recommendation G.826 Lmin Llink 500 km 500 km 5-15 2.5 103(1 + BR) 0 2.5 1035 104 B
14、RESR 15-55 3.75 103(1 + BR) 0 3.75 1037.5 104 BRESR 55-160 8 103(1 + BR) 0 8 1031.6 103 BRESR 160-400 Not applicable Not applicable Not applicable Not applicable SESR 400 1 104(1 + BR) 0 1 1042 105 BRBBER 1.5-400 1 105(1 + BR) 0 1 1052 106 BR2 that the EPOs for the access and short haul sections sho
15、uld make use only of the block allocation contribution specified in ITU-T Recommendations G.826 and G.828 for the national portion of a 27 500 km HRP and HRC, and that the long haul section should make use of the distance-based allocation and part of the fixed block allowance allocation; Rec. ITU-R
16、F.1668-1 5 3 that for the EPOs applicable to each direction of any real fixed wireless link of length Llinkbelonging to the long haul inter-exchange network sections of the national portion of HRP and HRC the values in Table 3a for SDH systems designed according to ITU-T Recommendation G.828 and in
17、Table 3b for other systems designed according to ITU-T Recommendation G.826 should apply. The lower limit of Llink, used to scale the objectives to the real case, is Lmin= 50 km. TABLE 3a EPOs for real SDH fixed wireless links belonging to the long haul inter-exchange network section of the national
18、 portion of the HRP according to ITU-T Recommendation G.828 Rate (Mbit/s) 1 664 (VC-11, TC-11) 2 240 (VC-12, TC-12) 6 848 (VC-2, TC-2) 48 960 (VC-3, TC-3) 150 336 (VC-4, TC-4) ESR 0.01 A 0.01 A 0.01 A 0.02 A 0.04 A SESR 0.002 A BBER 5 105 A 1 104 A TABLE 3b EPOs for real fixed wireless links belongi
19、ng to the long haul inter-exchange network section of the national portion of the HRP and HRC according to ITU-T Recommendation G.826 Rate (Mbit/s) 5 to 15 15 to 55 55 to 160 160 to 400 ESR 0.04 A 0.04 A 0.05 A 0.075 A 0.16 A Not applicable SESR 0.002 A 0.002 A 0.002 A 0.002 A 0.002 A 0.002 A BBER(1
20、)Not applicable 2 A 1042 A 1042 A 1042 A 1041 A 104(1)BBER parameter is applicable only to paths. where: A = (A1+ 0.002) Llink/100 for 50 km Llink 100 km A = A1+ 2 105Llink for 100 km 5 to 15 15 to 55 55 to 160 160 to 400 ESR 0.04 B 0.04 B 0.05 B 0.075 B 0.16 B Not applicable SESR 0.002 B 0.002 B 0.
21、002 B 0.002 B 0.002 B 0.002 B BBER Not applicable 2 B 1042 B 1042 B 1042 B 1041 B 104The value of B has provisionally been agreed to be in the range of 0.075 to 0.085 (7.5% to 8.5%) (see Notes 3 and 4); 5 that for the EPOs applicable to each direction of any real fixed wireless link forming all of t
22、he access network sections of the national portion of the HRP and HRC the values given in Table 5a for SDH systems designed according to ITU-T Recommendation G.828 and in Table 5b for other systems designed according to ITU-T Recommendation G.826 should apply. TABLE 5a EPOs for SDH fixed wireless li
23、nks forming all of the access network section of the national portion of the HRP according to ITU-T Recommendation G.828 (see Note 6) Rate (Mbit/s) 1 664 (VC-11, TC-11) 2 240 (VC-12, TC-12) 6 848 (VC-2, TC-2) 48 960 (VC-3, TC-3) 150 336 (VC-4, TC-4) ESR 0.01 C 0.01 C 0.01 C 0.02 C 0.04 C SESR 0.002
24、C BBER 5 105 C 1 104 C Rec. ITU-R F.1668-1 7 TABLE 5b EPOs for fixed wireless links forming all of the access network section of the national portion of the HRP and HRC according to ITU-T Recommendation G.826 (see Note 6) Rate (Mbit/s) 5 to 15 15 to 55 55 to 160 160 to 400 ESR 0.04 C 0.04 C 0.05 C 0
25、.075 C 0.16 C Not applicable SESR 0.002 C 0.002 C 0.002 C 0.002 C 0.002 C 0.002 C BBER Not applicable 2 C 1042 C 1042 C 1042 C 1041 C 104The value of C has provisionally been agreed to be in the range of 0.075 to 0.085 (7.5% to 8.5%) (see Notes 3 and 4); 6 that for the EPOs evaluation in recommends
26、1 to 5 the error-performance parameters for any real link are defined as follows: ESR is the ratio of errored second (ES) events to total seconds in the available time during a fixed measurement interval; SESR is the ratio of severely errored second (SES) events to total seconds in the available tim
27、e during a fixed measurement interval; BBER is the ratio of background block error (BBE) events to total blocks in the available time during a fixed measurement interval. The count of total blocks excludes all blocks during SESs. NOTE 1 The EPOs apply only when the system is considered to be availab
28、le. The entry and exit criteria into and from the unavailable state are defined in Annex A of ITU-T Recommendations G.826 and G.828. NOTE 2 The objectives given in this Recommendation are understood to be long-term objectives to be met over an evaluation period of a month, which is understood to be
29、any period of 28 to 31 (typically 30) consecutive 24 h intervals. These objectives should be respected for any month (see Recommendation ITU-R P.581). To be able to compare measurement results taken by different parties on the same path, start time and duration of the performance evaluation period n
30、eed to be agreed between the parties concerned. NOTE 3 The sum of the percentages A1% + B% + C% should not exceed 17.5%, in accordance with the allocations to the national portion of an international CBR path or connection given in ITU-T Recommendations G.826 and G.828. NOTE 4 The provisional values
31、 agreed for B% + C% are in the range 15.5% to 16.5%. NOTE 5 Depending on national network configurations administrations may reallocate the A%, B% and C% block allowances among the sections of the national portion of a radio path. NOTE 6 A real link is defined as a portion of a path or connection co
32、ming from partitioning and it is characterized by its real length Llink. NOTE 7 There is a great variety in the architecture of access networks in different countries. If the radio path forms only part of the short haul or access network section, it is at the discretion of administrations to make an
33、 appropriate apportionment of the objectives given in Tables 4a, 4b, 5a and 5b as a block allowance to the elements forming the short haul or access network section. 8 Rec. ITU-R F.1668-1 NOTE 8 In the case of multi-hop links the objectives derived according to this Recommendation apply to the overa
34、ll links (irrespective of the date when each hop was brought into service and of the number of independent operators involved); the allocation of the objectives to each hop is under the responsibility of the network operators. NOTE 9 The ES, SES and BBE events and the block structure for SDH multipl
35、ex and regenerator sections are defined in ITU-T Recommendation G.829, the ES, SES and BBE events, and the block structure for paths and connections are defined in Annex A of ITU-T Recommendation G.826. NOTE 10 The effect of interference and all other sources of performance degradations are included
36、 in Tables 1-5. NOTE 11 In the context of this Recommendation, the link consists in section(s) and/or path(s) or connection(s). NOTE 12 Annexes 1, 2 and 3 may be used for additional guidance in the application of this Recommendation. Annex 1 Example of a connection, path, link, hop This Annex clarif
37、ies the meaning of some terms related to the connection, used in the body of the Recommendation. The definitions of path and connection are given in ITU-T Recommendation G.826; an example of a fixed wireless link forming a portion of a path is given in Fig. 2. Rec. ITU-R F.1668-1 9 Annex 2 Error per
38、formance events for different SDH fixed wireless link configurations 1 Introduction In a fixed wireless link the link end-points, which are represented by the fixed wireless terminal at the two sides of the link, may terminate a path, multiplex section and regenerator section. All configurations are
39、 possible according to the definition given in ITU-T Recommendation G.783 and Recommendation ITU-R F.750. The examples in this Annex show the relationship between the main practicable configuration for SDH link and the estimation of error performance events (ES, SES and BBE). The fixed wireless spec
40、ific performance monitoring in the presence of a protection switching is defined in Recommendation ITU-R F.750. 2 Link end-points are path end-points with and without frequency diversity The B3 or V5 byte, dealing with high order path and low order path respectively, are calculated/evaluated in both
41、 link end-points. Error performance events are defined in ITU-T Recommendation G.829. 3 Link end-points are SDH multiplex section end-points 3.1 One hop multiplex section without frequency diversity protection The B2 byte is calculated/evaluated in both link end-points, while the B3 and V5 byte are
42、passed transparently through the link end-points without modification. Error performance events are defined in ITU-T Recommendation G.829. The comparison of the values of relative error performance parameters, obtained by means of B2 byte according to ITU-T Recommendations G.829 and G.783, with the
43、objectives defined in this Recommendation could be considered as an estimation. The accuracy depends on the number of errors per burst. 3.2 One hop multiplex section with frequency diversity protection The error performance monitoring functionalities of the protected section, i.e. the section outsid
44、e the protection switching depends on the allocation of SDH fixed wireless radio protection switching (RPS) function blocks, as described in Recommendation ITU-R F.750. In case of type C allocation, defined in Recommendation ITU-R F.750, the B1 byte is calculated/evaluated in both link end-points pe
45、r each channel (i.e. working channels and protecting channel). The B2 is calculated/evaluated in both link end-points outside the protection section, so it gives directly the performance of the protected section. The B3 and V5 byte are passed through the link end-points without modification. Error p
46、erformance events are defined in ITU-T Recommendation G.829. The comparison of the values of relative error performance parameters, obtained by means of B2 byte according to ITU-T Recommendations G.829 and G.783, with the objectives defined in this Recommendation could be considered as an estimation
47、. The accuracy depends on the number of errors per burst. 10 Rec. ITU-R F.1668-1 In case of type B allocation, defined in Recommendation ITU-R F.750, the B1 and B2 bytes are calculated/evaluated in both link end-points per each channel (i.e. working channels and protecting channel). The B3 and V5 by
48、te are passed through the link end-points without modification. Two processes may, in this case, be possible for the fixed wireless protected section quality: the first one is to evaluate separately the quality of the synchronous transport module of order (STM-N) signal at the input and at the outpu
49、t from the protected radio fixed wireless section by means of not intrusive monitoring of B3 bytes and to let the/a management system provide the difference; the second one is to send forward, through a media dependent byte of the regenerator section overhead passed transparently through any intermediate repeater acting as MS, the bit interleaved parity, BIP-8 equ
