1、 Rec. ITU-R F.1330-2 1 RECOMMENDATION ITU-R F.1330-2*Performance limits for bringing into service the parts of international plesiochronous digital hierarchy and synchronous digital hierarchy paths and sections implemented by digital fixed wireless systems (Question ITU-R 161/9) (1997-1999-2006) Sco
2、pe This Recommendation provides BIS performance limits for international PDH and SDH paths and sections implemented using FWS. The approach is aligned to the ITU-T BIS approach, but some media-specific (FWS) aspects are incorporated. The Annex details the application of the performance limits for BI
3、S. The ITU Radiocommunication Assembly, considering a) that digital fixed wireless systems for use in constant bit-rate digital paths at or above the primary rate in the international portion of a 27 500 km hypothetical reference path (HRP) are being designed; b) that there is a need to specify “bri
4、nging into service” (BIS) performance limits for digital fixed wireless systems; c) that the performance limits and procedures for maintenance activities for digital fixed wireless systems have been defined in Recommendation ITU-R F.1668; d) that ITU-T has prepared performance limits for bringing-in
5、to-service and maintenance of international multi-operator plesiochronous digital hierarchy (PDH) path, connections in ITU-T Recommendation M.2100 and for international multi-operator synchronous digital hierarchy (SDH) paths and international SDH multiplex sections in ITU-T Recommendation M.2101, b
6、eing based on ITU-T Recommendation G.826 and G.828 respectively; e) that ITU-T Recommendation M.2110 provides procedures for the BIS of international multi-operator digital paths, sections and transmission systems with and without in-service monitoring (ISM); f) that ITU-R has approved Recommendatio
7、n ITU-R F.1660 for error performance objectives for real digital fixed wireless links used in 27 500 km hypothetical reference paths and connections; g) that propagation conditions may adversely affect the BIS procedures for digital fixed wireless systems; h) that the influence of propagation condit
8、ions on the BIS procedures for digital fixed-wireless systems currently under study in Radiocommunication Study Group 3; *This Recommendation should be brought to the attention of Radiocommunication Study Groups 3 and 4, and Telecommunication Standardization Study Groups 4 and 13. 2 Rec. ITU-R F.133
9、0-2 j) that performance limits and procedures for the BIS of PDH and SDH constant bit rate paths and sections based on digital fixed-wireless systems should be defined; k) that BIS performance objectives (BISPOs) should take into account a suitable margin, to minimize subsequent maintenance interven
10、tions; l) that due consideration of propagation conditions should be taken when undertaking BIS measurements; noting a) that for the purpose of allocating the performance objectives for the international portion of a constant bit rate path at or above the primary rate using digital fixed-wireless sy
11、stems, an international digital path has been partitioned in geographical terms; these portions have been titled path core elements (PCE). Two types of international PCE are used: an international PCE (IPCE) between an international gateway and a frontier station in a terminating country, or between
12、 frontier stations in a transit country (see Note 1); an inter-country PCE (ICPCE) between the adjacent frontier stations of the two countries involved. The ICPCE corresponds to the highest order digital path carried on a digital transmission system linking the two countries; recommends 1 that the l
13、imits for BIS should be based on end-to-end reference performance objectives (RPOs) shown in Tables 1a and 1b as well as allocations shown in Table 2; TABLE 1a (See Note 2) RPO PDH Primary (Note 4) Secondary Tertiary Quaternary SDH (Mbit/s) 1.5 to 5 5 to 15 15 to 55 55 to 160 160 to 3 500 Parameter
14、End-to-end RPO Errored seconds ratio (ESR) for paths designed according to G.826 0.02 0.025 0.0375 0.08 Not applicable (NA) Errored second ratio (ESR) for paths designed according to G.828 0.005 0.005 0.01 0.02 (NA) Background block error ratio (BBER) for SDH paths designed according to G.828 2.5 10
15、5 2.5 105 2.5 105 5 105 5 105 Severely errored seconds ratio (SESR) 0.001 0.001 0.001 0.001 0.001 Rec. ITU-R F.1330-2 3 TABLE 1b RPO for end-to-end international SDH multiplex sections Rate STM-0 STM-1 STM-4 Blocks/second 64 000 192 000 768 000 ESR (according to G.826) 0.0375 0.08 NA ESR (according
16、to G.828) 0.01 0.02 NA SESR 0.001 0.001 0.001 BBER (according to G.826) NA NA NA BBER (according to G.828) 2.5 105 5 105 5 105 TABLE 2 Allocation, an PCE classification (see Note 3) Allocation (% of end-to-end RPOs) IPCE Terminating/transit national networks: d 100 km 1.2 100 km 7 500 km 10.0 ICPCE
17、d 300 km 0.3 International multiplex section 0.2 2 that the allocated performance objective (APO) and the BISPO for the BIS of a path and a multiplex section should be calculated as follows: for a path APOes= A% RPOes TP 100 (convert A% to ratio) APOses = A% RPOses TP 100 (convert A% to ratio) APObb
18、e= A% RPObbe TP 2 000 100 (convert A% to ratio VC-1 and 2) APObbe = A% RPObbe TP 8 000 100 (convert A% to ratio VC-3 and 4 and VC-4-Xc) 4 Rec. ITU-R F.1330-2 for a multiplex section APOes = A% RPOes TP 100 (convert A% to ratio) APOses = A% RPOses TP 100 (convert A% to ratio) APObbe = A% RPObbe TP 64
19、 000 100 (convert A% to ratio STM-0) APObbe = A% RPObbe TP 192 000 100 (convert A% to ratio STM-1) APObbe = A% RPObbe TP 768 000 100 (convert A% to ratio STM-4) where: A% = anN1% for a path i.e., A% = a1% + a2% + . + aN% an: allocation for each IPCE and ICPCE forming the path A% = a% for a multiplex
20、 section TP : test period (s) BISPO = APO /Fm where Fm is the maintenance margin; 3 that for the definition of BISPO the following maintenance margin Fm should be specified: TABLE 3 Maintenance margins, Fm Maintenance margin, Fm For normal propagation conditions (Note 5) For adverse propagation cond
21、itions (Notes 5 and 6) PDH paths and sections SDH paths 2 0.5 PDH transmission systems SDH multiplex sections 10 0.5 4 that test periods (TPs) for BIS of digital fixed wireless systems have been designed as follows: for all radio paths and sections, a 24-h BIS test period should be used and the perf
22、ormance must satisfy the calculated S24limits for each error performance parameter (see Annex 1); for radio paths and sections with performance falling between the S1 and S2 performance limits during the 24-h test period and that are continuously monitored during operation (with in-service monitorin
23、g (ISM), a further extended 7-day BIS test period should be undertaken; for radio paths and sections with performance falling between the S1 and S2 performance limits during the 24-h test period and that are not monitored during operation (non-ISM), provisional acceptance or BIS re-testing should be
24、 undertaken, subject to agreement between the parties; Rec. ITU-R F.1330-2 5 for new radio paths and sections over routes where no radio paths or sections are present and during periods of adverse propagation conditions, an extended 7-day BIS testing period should be used and the performance must sa
25、tisfy the calculated BISPO for each error performance parameter; 5 that Annex 1 contains guidance and further details on the BIS limits, test procedures and methodology for calculating the BISPOs and their limits. NOTE 1 The definitions of an international gateway and a frontier station can be found
26、 in ITU-T Recommendation M.2101. NOTE 2 It is the responsibility of each country to design its network in a way that is consistent with its country allocation for the international path. NOTE 3 The lengths d referred to in Table 2 are actual route lengths or air-route distances multiplied by an appr
27、opriate routing factor, Rf, whichever is less; for multiplex sections the length d refers to the actual distance only (see ITU-T Recommendation M.2100): TABLE 4 PCE great circle length vs. routing factor PCE great circle length Routing factor (Rf) Calculated PCE length d 1 000 km 1.5 1.5 d km 1 000
28、km d 1 200 km 1 500/d 1 500 km d 1 200 km 1.25 1.25 d km NOTE 4 For international multi-operator connections using equipment designed according to revised ITU-T Recommendation G.826 RPO for PDH primary rate could be used. NOTE 5 The periods of normal and adverse propagation conditions may change fro
29、m country to country and therefore it is the responsibility of the interested parties to reach agreement. NOTE 6 If it is defined that the BIS procedure should take place during X month (X month is up to 3 and it is under mutual agreement between the interested parties) before or after the period wi
30、th adverse propagation conditions the value Fm = 1 may be used under mutual agreement between the interested parties. Annex 1 Performance limits and methodology for BIS 1 BIS testing procedures The BIS testing procedures for the bringing into service of international PDH paths, sections and transmis
31、sion systems and SDH paths and sections, including how to deal with any period of unavailability during the test, are defined in ITU-T Recommendation M.2110 and may be applied to digital fixed wireless paths, sections and transmission systems during periods of normal propagation. 6 Rec. ITU-R F.1330
32、-2 However, in order to take due consideration of the effects of propagation and the periods of adverse propagation that may influence the performance of fixed wireless systems, the following BIS testing procedures and steps should be used. The testing procedures are divided into two discrete steps;
33、 namely: An initial (15-min) testing period, to provide initial proof of performance of the radio system under test. BIS testing for the full TP, as appropriate to the radio system under test (see recommends 4). 1.1 Initial testing procedure (Step 1) Initial measurements should be performed over a 1
34、5-min period of time, using a measuring instrument with a framed pseudo-random bit sequence (PRBS). During this 15-min period of time there should be no errors or unavailability events. If any error or unavailability event is observed, the test should be halted and repeated. The initial testing may
35、be repeated twice. If, during the third (and the last) test, there is any error or unavailability event, the radio system should be withdrawn from testing and fault localization and correction must be performed. It is recommended that the initial (15-min) tests are performed during a period of the d
36、ay where clear-air propagation conditions exist and where the probability of adverse propagation conditions is minimal (normally this period is between 10:00 and 14:00 h local time). 1.2 Main testing procedure (Step 2) After successfully passing Step 1 (initial testing procedure), a test over a 24-h
37、 period of time is applied. Real traffic could be carried if (ISM) is available. However, if ISM is not available, the testing is performed under the same conditions as for initial testing (i.e. using a measuring instrument). At the end of the 24-h period of time, the results of the measurements are
38、 compared to the BIS limits S1 and S2 (see 2 and 3). Should an unavailability event occur at any time during the BIS testing, the cause should be investigated and a new BIS test re-scheduled. Should a further unavailability event occur in the second BIS test, then BIS testing should be suspended unt
39、il the cause of the unavailability event has been resolved. The outcome of all BIS tests should be recorded for future reference. 2 The methodology of calculation of BIS performance limits The following steps shall be followed to obtain path performance limits: Identify the bit rate of the path. Rea
40、d the RPOs for the appropriate bit rate from Table 1a or 1b for each error performance parameter (ESR, SESR and BBER). Identify all PCEs for the entire path, and set N = the total number of PCEs. Identify the length, d, of each PCE.n (n = 1 to N). The length, d, is either the actual path length or c
41、an be estimated by the great circle length between its end points multiplied by the appropriate routing factor Rf (see Note 3 above). Rec. ITU-R F.1330-2 7 Take the allocation, an%, (as a percentage of end-to-end RPO) for PCE.n (n = 1 to N) from the Table 2. Note that the allocations in Table 2 are
42、maximum values; more stringent values can be used by bilateral or multi-lateral agreement. Calculate A%, the path allocation, where: A% = anN%1 Determine the required TP in accordance with recommends 5 (24 h or 7 days). Express TP in seconds, e.g., TP = 86 400 s for a 24-h TP and TP = 604 800 s for
43、a 7-day TP. Calculate the APOs for ES and SES required from the information already obtained: APO = A% RPO% TP 100 (convert A% to ratio) Calculate the BISPOs for the path: BISPO = APO /Fm where Fm is the maintenance margin (see recommends 3). For TP = 24 h, calculate S1 and S2 values for each error
44、performance parameter: S1 = BISPO 2 BISPO S2 = BISPO + 2 BISPO round all S1 and S2 values to the nearest integer value. In some cases the BBE S limits are non-zero while the ES limits are zero or invalid (i.e. do not provide 95% confidence that the BISPO will be met long term). It is generally sugge
45、sted that a longer test be used where the ES limits are invalid. In either case, the BBE test cannot be accepted if there is more than 1 ES. Note that if any PCE within a path is changed, then the entire calculation process must be repeated, since the S1 and S2 values are non-linear. A similar proce
46、dure could be used for PDH transmission systems and SDH multiplex sections but Fm should be taken in accordance with recommends 3. 3 BIS limits and conditions The evaluation of the BIS test results, using the S1 and S2 performance limits, as calculated using the methodology contained in 2 are detail
47、ed in 3.1, 3.2, 3.3 and in Fig. 1. 8 Rec. ITU-R F.1330-2 3.1 BIS radio paths and sections not monitored during operation (with non-ISM) The two steps of the BIS testing procedure, as described above, must be performed using a measuring instrument. At the end of Step 2 testing, the following scenario
48、s are possible: if all error performance parameters are less than or equal to their respective S1 values, the radio path or section is accepted and becomes ready for service; if any error performance parameters (or all) are greater than or equal to their respective S2 values, the radio path or secti
49、on is rejected and appropriate fault localization procedures begin; if any error performance parameters (or all) are greater than their respective S1 values, but all are smaller than their respective S2 values; the radio path or section can be either provisionally accepted, or re-tested, subject to bilateral or multilateral agreement. 3.2 BIS radio paths and sections continuously monitored during operation (with ISM)
