Flexi Multiradio BTS Module Reliability

RELIABILITY COMMUNICATION MATERIAL FLEXI MULTIRADIO BTS Module reliability Annex 1. Version 3.0

Document Code/Version Sharenet 13-516364/3.0

© 2010 Nokia Siemens Networks Oy Proprietary and Confidential

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Nokia Siemens Networks

RELIABILITY COMMUNICATION MATERIAL FLEXI MULTIRADIO BTS ANNEX1: Module reliability

1. MODULE AND SUB-MODULE RELIABILITY DATA 1.1 Introduction for this document This annex defines the module and sub-module level reliability values for Flexi WCDMA BTS (Release 1. HW) and Flexi Multiradio BTS (Release 2. HW). Values are meant to estimate a mature product spare part need, but also they are used to estimate a BTS system expected reliability in the field use. This document need to be used with Reliability Communication Material for BTS Systems and Configurations document (445958). Versioning follows that main document versioning. 1.2 Restrictions and limitations for the communicated reliability data When the field failure rates (MTBF) are compared to the predicted values, it is necessary to notice the difference of component failures used in prediction and the field failures. To make the field MTBF value comparable to predicted one, it is needed to use next restrictions for data: • • • •

•

• •

Module must have about 10 000 000 hours (1 100 years) field use hours before the field results is able to state accurate enough MTBF level. o This can be reached when > 1000 modules is one year on the field. Predicted value is valid during the product lifetime only (BTS 10 years). Failure rates (MTBF) are defined for electrical parts only and typically only for repairable items. Non-repairable items reliability is assumed to fulfil 10 years lifetime if not otherwise stated and they are not included to predicted value typically. Predicted values are valid in the calculation conditions only, not in the product specified conditions directly. o BTS air (ambient) temperature, which is used based on the common climate conditions: Humid Temperate, average +15°C. • Warmest month > 10 C (> 50 °F). • Coldest month > 0 C but < 18 C (> 32 °F but < 64.4 °F ). • Most populated, about 55 % of world's population. • Like Mid-European, Mediterranian, Mid Asia and North-America costal climates. • Value also valid for typical air-conditioned indoor site. Tropical/Sub-tropical climate, average +25°C. • Coldest month > 18 C (> 64.4 °F ). • Like South Asia, most India and equator climates. • Daily and annual temperature range about +10…+50°C. o Assumes an average RF-output power. Long-term RF-power load about 50% of maximum. o Operating more than 30 minutes in temperatures over +40°C is not recommended to avoid errors or total failure in operation. Exludes the failures, which are not direct design weaknesses. o “No Fault Found” (NFF’s). o External and misuse failures. Equipment handling and usage errors. Failures caused by other network element or external system. Exludes systematic failures caused by 3rd party. o Systematic part failures caused by manufacturer process weakness. Cooling fans are included if not otherwise stated.



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For selected units for which MTBF for repair values are not relevant (like non-repairable tiems mostly), design lifetime, MTTF (Mean Time To Failure) or L10 life or similar life values are given. It is expected that non-repairable items can work in normal conditions over the product lifetime. 1.3 Reliability terminology and calculation principles Reliability of modules in this document is expressed with next terminologies and calculation formulas. Please note that terminologies and calculation principles can differ between organizations and reliability standards. To avoid conflicts between contract participants, the details of terms need to be understood and clarified more exactly to avoid misreading. Mean (operating) Time Between Failures (MTBF) The expectation of the operating time duration between two consecutive system failures of a repaired item. MTBF for Repair comprises all failures requiring repair whether they affect the system functionality or not. It summaries the parts FIT’s (Failure In Time) and indicates the probability for unplanned site visit. Value is calculated by SN29500 Parts Stress method if any other standard or method is not mentioned. Value is calculated for nominal use conditions in the most common environmental condition. Module ambient temperature used in the calculation as a reference temperature is +25°C corresponding nominal indoor conditions and high outdoor temperature conditions (subtropical/tropical climate). In adiition it is calculated most common BTS site outdoor temperature conditions +15°C (moderate climate), which is most valid also for mast conditions in high temperature areas. Module System MTBF indicates the expected failure rate for the module including redundancy or other reliability function improving the reliability performance compared to the MTBF for Repair value. This happens in example in Flexi System Module, where 2 or 3 baseband card combinations offers clear improvement to serve full or partial baseband capacity in failure cases.



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2. MTBF FOR REPAIR FOR FLEXI MULTIRADIO MODULES AND SUB-MODULES 2.1 RF Modules and Radio Remote Heads MTBF for Repair RF Modules and RRHs

+25 °C [hours]

+15 °C [hours]

1- sector RF Module Release 1. 2- sector RF Module Release 1. 3- sector RF Module Release 2. RRH 1TX RRH 2TX

220 000 160 000 150 000 210 000 200 000

300 000 240 000 210 000 300 000 280 000

System Modules and sub-modules

+25 °C [hours]

+15 °C [hours]

FSMB SYSTEM MODULE Release 1. (including transport sub-module, fan assembly and FPFA) FSMB SYSTEM MODULE (excl. transmission) FSMD System Module, 2xBB with transmission FSMD System Module, 2xBB without transmission FSME System Module, 3xBB with transmission FSME System Module, 3xBB without transmission FPFA (AC-PSU sub-module) FPFB (DC-PSU sub-module)

120 000

160 000

160 000 120 000 160 000 100 000 140 000 2 800 000 2 000 000

220 000 160 000 220 000 140 000 200 000 3 600 000 2 800 000

Transmission sub-modules

+25 °C [hours]

+15 °C [hours]

FTEB PDH E1 asymmetric FTFA Flexbus FTIA PDH E1/T1/JT1 symm. and Ethernet FTIB PDH E1/T1/JT1 symmetric and ethernet FTJA PDH E1 asymmetric and Ethernet FTHA PDH E1/T1 High Density FTOA Optical STM-1/OC-3 FTLA Ethernet/PDH high-performance FTLB Ethernet/PDH high-performance

500 000 420 000 420 000 420 000 420 000 460 000 500 000 420 000 420 000

700 000 600 000 600 000 600 000 600 000 650 000 700 000 600 000 600 000

2.2 System Module with sub-modules data MTBF for Repair

MTBF for Repair



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MTBF for Repair Power Supply sub-modules FPAA FLEXI POWER AC/DC SUBMODULE 230V FPBA FLEXI POWER BATTERY SUBMODULE FPAB FLEXI POWER AC/DC SUBMODULE 230V FPDA FLEXI POWER DC/DC MODULE 24V

+15 °C [hours]

+25 °C [hours]

2 000 000 2 800 000 3 000 000 2 000 000

3 000 000 4 200 000

4 500 000 3 000 000

3. FLEXI SYSTEM MODULE SYSTEM MTBF This table defines the benefit of signal processor (baseband card) redundancy in whole System Module containing also transmission sub-module. Data shows the module system MTBF for possible baseband card failure scenarios. Data is for +25 °C ambient temperature. System MTBF

System MTBF

2 BB

1 BB

(A/%)

(MAIDT)

170 000h

280 000h

99.99970

< 1.6 min/y

System MTBF

System MTBF

System MTBF

3 BB

2 BB

1 BB

(A/%)

(MAIDT)

140 000

180 000

280 000

99,99964

< 1.9 min/y

FSMD 2 baseband (BB) cards

FSME 3 baseband (BB) cards

Availability Mean Down Time 2xBB

Availability Mean Down Time 3xBB

Mean Repair Time = 30 minutes in Availability calculations. .



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4. DESIGN LIFETIME DATA FOR SELECTED FLEXI MULTIRADIO BTS ITEMS Sales item

Lifetime [years]

System Module FSKA FLEXI SYSTEM EXTENSION KIT

> 10

Power Systems FPMA FLEXI POWER MODULE

> 10

Cabinets and cabinet options FCOA FLEXI CABINET OUTDOOR

> 10

FCIA FLEXI CABINET INDOOR

> 10

FCDA FLEXI CABINET FIRE DETECTOR

> 10

FCFA FLEXI CABINET AIR FILTER (see Note 1)

> 10

FCSA FLEXI CABINET SITE SUPPORT MODULE

> 10

FSEA FLEXI SYSTEM EXTERNAL ALARM

> 10

FSEB FLEXI SYSTEM EXTERNAL ALARM

> 10

FSEC FLEXI SYSTEM EXTERNAL OVP

> 10

FSFB FLEXI SYSTEM FIBRE B 50m

> 10

FSFC FLEXI SYSTEM FIBRE C 100m

> 10

FSAA FLEXI SYSTEM ALARM CABLE 15m

> 10

EXTPOWER FIXING KIT FOR POLE INSTALLATION

> 10

Mounting kits for modules FMCA 3U MOUNTING COVERS FRONT AND BACK

> 10

FMCB 2U MOUNTING COVERS FRONT AND BACK

> 10

FMUA FLEXI MOUNTING KIT VERTICAL FOR 2G ULTRASITE

> 10

FMUB FLEXI MOUNTING HORISONTAL KIT FOR 2G ULTRASITE

> 10

FTCM OD ADAPTER CABLE RJ48-C 120 ohm

> 10

FTCN OD ADAPTER CABLE SMB 75 ohm

> 10

FTCO OD ADAPTER CABLE TNC

> 10

FMFA FLEXI MOUNTING KIT

> 10

VMPB POLE MOUNTING KIT

> 10

MIBBU System FMBA FLEXI MOUNTING KIT FOR BATTERIES

> 10

FMBB FLEXI MOUNTING KIT FOR BATTERIES

> 10

Outdoor transmission cables FTCB OD CABLE RJ48C 120ohm 15M

> 10

FTCE OD CABLE SMB-F/0 75ohm 15M

> 10

FTCH OD CABLE LC SM 1310 15M

> 10

FTCA OD CABLE RJ48C-TQ-M/0 120ohm 5M

> 10

FTCD OD CABLE SMB-F/0 -BT43-F/0 75ohm 5M

> 10

FTCR OD CABLE RJ45 CAT5E 15m

> 10

FTCJ OD CABLE TNC–F/0–TNC M/0 50 ohm 2.5m

> 10



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4.1 Life and reliability data for selected Flexi Multiradio BTS items Sales item/unit

Value in

Value in

Hours

Years

93 000h

10.6

70 000

8.0

RF/System/Power module Fan assembly L10 ( one fan value) FCFA Flexi cabinet air filter *

)

Fan assembly L10 (one fan value) FCSA Flexi cabinet site support module Fan assembly L10 (one fan value) Cooling fan MTTF for spare part calculation

70 000

8.0

4 000 000

456

*) Note! Design lifetime prediction of FCFA Flexi cabinet air filter unit does not include the filtering element. Maintenance interval of the filtering element varies depending on the environmental conditions. Typical air filter replace time is from one year upto 5 years depending on the site conditions.

5. RELIABILITY BLOCK DIAGRAM MODELS Presented models represents most common BTS and module structures. 5.1 System Module FSME with three baseband card BB Power Supply

Cooling FANs

BB Control

Transmission BB

BB

FSMD is similar to FSME, but has only two baseband cards and thus 2/3 baseband capacity of FSME. Power supply includes powering and filtering to whole module. Cooling fan assembly contains two fans with fan control circuit. BB-control forms the needed clock signals and controls to the module operation. The transport sub-module forms the needed transmission functionality. Baseband cards are in BB-pool to maintain partial service capability in failure cases. Cooling fan assembly contains two fans, in which failure in other do not affect to module functionality in normal use condition (typical up to +40°C) . Other reliability techniques to optize design performance are explained in the Reliability Communication Material for Flexi Multiradio BTS Systems and Configurations Reliability.



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5.2 RF Modules and RRHs design structure All the RF Modules and RRHs contain mostly similar design structure and main difference comes in frequency bands (frequency variants). RF Module contains typically cooling fans to keep thermal conditions more efficiently on same level. This often means that module level reliability is some amount higher to RRHs. Naturally thermal design is done so that the specified environmental conditions are fulfilled in the accepted site conditions. RF Modules and RRHs typically contain the common sub-modules and then one to three TRX depending on the module. TRXs are working separately and failure in one TX-path means the loss of that sector transmitting. Similarly, loss of one RX-path means on most cases only loss of diversity and if both RX-paths fails, then loss of receiving in that sector. Failure in common parts, like internal power supply, means the loss of whole RFcapacity. To avoid this, the RF Module and whole system contains sophisticated test, alarm and recovery functions to detect the errors proactively and prevent total failures. TX+PA+Filter

Example of 3-sector RF Reliability Block Diagram

RX+Filter

RF Power Supply

RX+Filter

RF Common

TX+PA+Filter RX+Filter

FAN Assembly (2 fans)

RX+Filter TX+PA+Filter RX+Filter RX+Filter

5.3 Transport sub-modules Depending on the transmission connection type, the transport design contains connection specific parts. Because the connection types needs different component technologies, the reliability (MTBF) value can vary some amount. On the system (BTS) level transport MTBF value is so high when it is compared to whole system module content, that effect to whole module MTBF values is not very significant. Thus on the system level it is used the estimated nominal value and not calculated values with all transmission sub-module cases.



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Flexi Multiradio BTS Module Reliability

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