1、Rec. ITU-R F.1400 1RECOMMENDATION ITU-R F.1400*,*PERFORMANCE AND AVAILABILITY REQUIREMENTSAND OBJECTIVES FOR FIXED WIRELESS ACCESSTO PUBLIC SWITCHED TELEPHONE NETWORK(Questions ITU-R 215/8 and ITU-R 140/9)(1999)Rec. ITU-R F.14001 IntroductionWireless access systems are a viable alternative to wireli
2、ne for service access to the public switched telephone network(PSTN). It is, therefore, desirable that the performance and availability of the wireless access systems be equivalent tothat provided by wireline.2 ScopeThis Recommendation summarizes the objectives and requirements relating to performan
3、ce and availability for wirelesstechnology used for PSTN network access. Fixed wireless access (FWA) is the connection between the user networkinterface (UNI) and the PSTN local exchange (LE) service node interface (SNI) (see Fig. 1).References to and extracts of material from existing ITU Recommend
4、ations dealing with performance and availabilityparameters are made where appropriate.In the framework of the generic ITU Recommendations, performance objectives and requirements are a function of theservice carried over the access. Requirements and objectives for basic telephony and low speed data
5、services are not asstringent as required for high speed data or integrated services digital network (ISDN) services. In recognition of thediffering requirements the following three classifications of services for wireless access systems have been used indeveloping this Recommendation:Type 1: Analogu
6、e signals such as voice and voiceband data at rates up to 64 kbit/s (minimum 3.1 kHz audio asidentified in ITU-T Recommendation G.174).Type 2: Access bearer service from 64 kbit/s to bit rates below the primary rate.Type 3: Digital services operating at the primary rate or above._*This Recommendatio
7、n was developed jointly by Radiocommunication Study Groups 8 (Working Party 8A) and 9 (WorkingParty 9B), and any further revision should be undertaken jointly.*This Recommendation should be brought to the attention of Radiocommunication Study Group 8 (Working Party 8A).2 Rec. ITU-R F.14001400-01Radi
8、oterminationcustomerlocationRadioaccessnetworkInterface fordigitalsignals(Note 2)UNI(Note 1)PSTN/LESNI(Note 1)(Wireless)FIGURE 1Reference section for performance and availability objectivesNote 1 Performance and availability criteria are defined at the SNI and UNI and should be measurable at these p
9、oints.Note 2 Physical layer of the interface should be based on ITU-T Recommendation G.703.FIGURE 1 1400-013 ReferencesITU-R Recommendations Recommendation ITU-R F.697: Error performance and availability objectives for the local-grade portion ateach end of an ISDN connection at a bit rate below the
10、primary rate utilizingdigital radio-relay systems Recommendation ITU-R F.757: Basic system requirements and performance objectives for fixed wireless localloop applications using cellular type mobile technologies Recommendation ITU-R F.1104: Requirements for point-to-multipoint radio systems used in
11、 local grade portionof an ISDN connection Recommendation ITU-R F.1189: Error performance objectives for constant bit rate digital paths at or above theprimary rate carried by digital radio-relay systems which may form part of thenational portion of a 27 500 km hypothetical reference path Recommendat
12、ion ITU-R F.1330: Performance limits for bringing into service of the parts of PDH and SDHpaths and sections implemented by digital radio-relay systemsITU-T Recommendations ITU-T Recommendation E.506: Forecasting international traffic ITU-T Recommendation E.541: Overall grade of service for internat
13、ional connections (subscriber-to-subscriber) ITU-T Recommendation G.113: Transmission impairments ITU-T Recommendation G.114: One-way transmission time ITU-T Recommendation G.173: Transmission planning aspects of the speech service in digital public landmobile networksRec. ITU-R F.1400 3 ITU-T Recom
14、mendation G.174: Transmission performance objectives for terrestrial digital wireless systemsusing portable terminals to access the PSTN ITU-T Recommendation G.175: Transmission planning for private/public network interconnection of voicetraffic ITU-T Recommendation G.703: Physical/electrical charac
15、teristics of hierarchical digital interfaces ITU-T Recommendation G.711: Pulse code modulation (PCM) of voice frequencies ITU-T Recommendation G.726: 40, 32, 24, 16 kbit/s adaptive differential pulse code modulation (ADPCM) ITU-T Recommendation G.728: Coding of speech at 16 kbit/s using low delay-co
16、de excited linear prediction ITU-T Recommendation G.821: Error performance of an international digital connection operating at a bit ratebelow the primary rate and forming part of an integrated services digitalnetwork ITU-T Recommendation G.826: Error performance parameters and objectives for intern
17、ational constant bit ratedigital paths at or above the primary rate ITU-T Recommendation G.827: Availability parameters and objectives for path elements of internationalconstant bit-rate digital paths at or above the primary rate ITU-T Recommendation H.221: Frame structure for a 64 to 1 920 kbit/s c
18、hannel in audiovisual teleservices4 RecommendationsThe ITU Radiocommunication Assembly recommends the following performance and availability requirements andobjectives for FWA systems. The performance objectives specified in 4.1 to 4.3 should be met for each direction oftransmission.The error perfor
19、mance objectives apply only when the system is considered to be in an available state. The entry and exitcriteria into and from unavailability state are defined in ITU-T Recommendations G.821 and G.826.4.1 Performance requirements and objectives for Type 1 FWA4.1.1 ServicesThe service provided via F
20、WA should be basic telephony services and data transmission up to 64 kbit/s.4.1.2 Voice MOS (mean opinion score)For bit-error ratio (BER) better than 1 103at the input to the decoder, the minimum performance of the wirelessaccess should be such that the voice MOS be equivalent to or better than the
21、voice quality corresponding to 32 kbit/sADPCM under the same condition.4.1.3 Voiceband data requirementa) For PSTN networks capable of supporting 9 600 bit/s, FWA should support a minimum data bit rate of 9 600 bit/s.b) The minimum BER for satisfactory transmission of data signals should be less tha
22、n 1 105.c) For 1 000-bit data block transmission the block error ratio (BLER) should be less than 1 102.4.1.4 Coding algorithmsIn the interests of efficient use of a limited spectrum resource a number of different coding algorithms may be used toreduce the bit rate required for voice transmission ov
23、er FWA systems. The impact of use of such encoding schemes on4 Rec. ITU-R F.1400the quality of speech communications and data transmission are documented in a number of Recommendations,e.g. ITU-T Recommendations G.113 and G.174 (see Annex 1).4.2 Error performance objectives for Type 2 FWAThe error p
24、erformance should meet the performance allocation for the local grade portion of connections identified inITU-T Recommendation G.821 and Recommendation ITU-R F.697.4.3 Error performance objectives for Type 3 FWAThe error performance of wireless access systems operating at bit rates at the primary ra
25、te or above should comply withRecommendation ITU-R F.1189 for access network sections.4.4 FWA availabilityThe design objectives for the two-way availability of the FWA should not be less than the following values includingboth propagation and equipment effects. The definition of unavailability for I
26、SDN connections is given for paths belowthe primary rate by ITU-T Recommendation G.821, and for paths at or above the primary rate by ITU-TRecommendation G.826.For Types 1 and 2 (see Note 1): 99.99% for medium quality applications; 99.999% for high quality applications (see Note 2).NOTE 1 For Types
27、1 and 2 connections, the outage intensity parameters are not applicable.NOTE 2 In order to achieve this objective including the customer location equipment, the mean time to repair (MTTR)should be sufficiently short.For Type 3 the availability objectives are yet to be defined.4.5 Traffic capacity -
28、grade of service (GOS) for FWA systemsThe radio access system capacity should be designed to accommodate 1% GOS (i.e. call blocking) with traffic levelsequivalent to wireline. A value of between 0.05 and 0.09 E per wireless access subscriber have been suggested forType 1. A higher allocation would b
29、e required to accommodate higher usage due to Internet access patterns.4.6 Signal transmission delay for FWAThe total incremental delay of a voice connection should be less than 40 ms as recommended for public land mobilenetwork (PLMN) planning in ITU-T Recommendation G.173 (the delay is inclusive o
30、f signal processing andpropagation delays). It has been suggested that the maximum incremental delay for wireless access systems be below20 ms.Connection delay impacts voice GOS and therefore, it is desirable that the incremental delay due to wireless accesssystems should be kept to a minimum. Echo
31、control measures should be considered when the one-way incremental delayis 5 ms or greater.4.7 Performance requirements for FWA to networks other than PSTNFurther studies are required in order to establish the relationship between severely errored second ratio (SESR), erroredsecond ratio (ESR), back
32、ground block error ratio (BBLER) and the performance parameters specifically applicable tonew services, such as Internet, packet data and multimedia that can be transported over FWA.Rec. ITU-R F.1400 5ANNEX 1Table 1 from ITU-T Recommendation G.174 provides guidance on the suitability of coder types
33、for the transmission ofmodem type data:TABLE 1Improvements in voiceband transmission rate may be achieved by digitally encoding the modem tones and bypassing thevoice encoder. The information would be reconverted to standard modem signal format at the wireless access terminalprior to interconnection
34、 with the PSTN.Signal coding method (ITU-T Recommendations)Modem type atmaximum data rateG.71164 kbit/sG.72640 kbit/sG.726(1)32 kbit/sG.72816 kbit/sV.21300 bit/sYes Yes Yes YesV.221 200 bit/s Yes Yes Yes YesV.27ter(2)4 800 bit/s Yes Yes Yes YesV.329 600 bit/s Yes Yes Yes FSV.29(2)9 600 bit/s Yes Yes
35、 No NoV.32bis14 400 bit/s Yes FS No NoV.17(2)14 400 bit/s Yes FS No NoV.3428 800 bit/s Yes FS No No56 000 bit/s Yes FS No NoFS: Further study is needed.Encoding algorithms are such that voice performance suffers little or no perceived degradation at radio channel error rates inexcess of 1 10 4.ITU-T
36、 Recommendation G.174 suggests that for typical modem applications (e.g. facsimile) the required BER measured at thenetwork interface should be 1 105and for less demanding applications (e.g. protected bulk data using 1000-bit blocks)BLER 1 102.(1)Entries based on ITU-T Recommendation G.721 standardization.(2)This modulation scheme is used for Group 3 facsimile.
