4. CDMA (WLL) BTS A/T

Transcription

1 Chapter 4

2 4. CDMA (WLL) BTS A/T 4-1 General: - There are two CDMA WLL systems introduced in BSNL these are: - 1 STAREX-WLL from LG for rural and urban, South Korea. 2. ZTE/ITI (UTL), Zing Tao Electronics, China. N.B. Please see block schematic, rack view of LG BTS in Figure no.s 4-1, 4-2, 4-3, 4-5, 4-6 and ZTE, LG actual rack front view in Fig LG CDMA WLL: - There are maximum 48 BTS accommodated in 1 BSC. - The number of subscriber per BTS (one FA/3 Sectors). - The number of FA/BTS are 8 (one FA=1.25MHz). - Standard BTS up to 8 FA/3 Sectors using LPA. - Outdoor BTS up to 4 FA/3 Sectors using HPA. - Two types of Antenna OMNI/3 Sectors/ Sectorial antenna. - Two E1 required out of one is Main and second is standby. - Number of sectors, α0 α1 β0 β1 γ0 γ1 - Sectorial type antenna gain 18 db, - Patch panel antenna gain 12 db. - Tx frequency = 0.03 N+ 870 (N= 347) - So Tx = MHz and Rx = Tx - 45 = MHz. RFE duplexer 10 MHz clock 10 MHz HPA P/S shelf RFIM 10 MHz TCM GPS STM- CARD 10 MHz TRx FDM aps TCM TRx TFS 1 FA system FDM Converts 10 MHz 12 MHz Frequency synthesizer BDS shell Base band digital sub Fig. 4-1 TRx Fig. 4-2 RFIM: - RF interface module Meters required for BTS A/T: - 1. Bird power meter 2. Through line watt meter model no. APM-16 50Ω (25, 50, 100 W) MHz 3. Bird antenna tester MHz 4. Site masters as mentioned in GSM Network. 117

3 4-2 Transmission A/T of BTS: Before proceeding for WLL BTS A/T, The following documents are necessary from the installer, 1. Offering memo in Performa (revised on 15 th Jan 2002) which contain all details about BTS. 2. Equipment room layout. 3. Trunking diagram of BTS and BSC. 4. SACFA clearance to be obtained. WICR WINR 2 PCM C E C BTS-0 Level D C I 2 PCM BTS O I T 2 PCM T Card A MBM Card BTS PCM Fig. 4-3 BTS Before starting A/T following Instructions are to be followed carefully, 1.Receiver sensitivity, RF frequency accuracy, spurious emission test and full band operation in the field for A/T purpose may not be carried out as these tests are already taken in Q/A testing. 2.A/T will check the digital map prepared by the vendor showing the predictable coverage with actual parameters. 3.When coverage is less than 90 % then approval of BSNL HQ is required to be obtained (As per Jt DDG (OP) circular) WLL A/T is to be carried out in two phases: - 1. Equipment A/T, 2. Coverage A/T. Please note:- - All items regarding infrastructure to be noted down as per test schedule. - Test of BTS hardware i.e. Initialization, Redundancy of device, power supply, and E1 link to be checked. - Fault handling test as per schedule to be tested. - Network test for display/ Change/ Addition/Deletion to be checked Equipment A/T i.e. RF parameters of BTS:- - Measure Trans Power by Bird power meter or by Site Master. Site Master shows reading in dbm as well as in watt also. - Open CDM- Displays parameter information and current power value Enter BTS no, sector no read out Trans Power. Limit: dbm (-4 to +2 dbm) Transpower can be monitored at BSM

4 2 Check of alarms: - Tx power, Rx power failure, and any Module Failure alarms are to be created and monitor on OMC and on card also. Write as OK/Not OK, also verify LPA alarm s LED for FAN, Loop, VSWR, P/S, Over Temp, Over power and critical, major, minor alarms. 3..Wave guide test :- Proceed as TSM BTS Test control Test VSWR BTS 0 sector α Antenna TX / Rx shows value of VSWR. Anritsu Site Master Mode Enter frequency as F1-824 MHz & F2 896 MHz Calibrate with open, short, load connectors, adjust M1 & M2 Markers.- signal Trace set markers read VSWR on display. Limit: Measure VSWR of all the six W/G cable i.e. α0 (Tx/Rx) α1 (Rx) β0 (Tx/Rx) β1 (Rx) γ0 (Tx/Rx) γ1 (Rx) 4. RF capacity test: - Purpose: - To check all the 16 calls for 32 channels holds good or not? No. of instruments (FWT)/Handset required 32. Arrange all 32 instruments in one BTS area for example say in telephone exchange first or second floor. Create all 32 numbers in OMC. - BSM CDM- Display parameters Display BTS count. Set RF capacity as: - CDMA 0 Chl no 347, TCE reserved voice 100 % and take out traffic print out. Make WLL-WLL 16 Calls and Monitor OK for10 minutes, or getting disconnected? Record as below, Time α β γ Total Check Trans media i.e. PCM links are from which system and whether it is acceptance tested or not? Coverage Test (Manual service quality test) Requirement:- 1. Obtain prediction coverage map. 2. Actual coverage road map FWT or Handsets and, Laptop with DM/SW for Recording. 4. Patch panel antenna. 5. Drive tool, Drive vehicle. Guidelines:- 1. Drive vehicle in each sector which include street, gullies,open area, Market area, some important locations and lanes of the street. 2. Make calls from inside shops and buildings. 3. Reach to the extreme of coverage area and make calls. 4. Total no of observations per sector to be minimum

5 Sl no 5. Go up to 25 Km and try calls with Patch panel antenna, beyond 25 Km also coverage may get. 6. All types of call are to be made i.e. WLL -WLL, WLL- PSTN, WLL- STD, and ISDN, Special services like, 187, 198, and Fax working WLL- WLL and WLL- PSTN. 8. The received signal strength should always be better than -99 dbm. 9. With Hand held test set ascertain call OK and Rx level 95 dbm up to 5 KM with FER less than 1x 10-2 with satisfactory call, and inside building up to 3 Km. Note down observation as follows and for sample pl. see chart. Location Radial distance Rx power Tx power FER call % status OK /Not OK. Results are to be compared with prediction coverage map. Patch panel Antenna is a 6 meters height Antenna as follows and with this antenna 25 to 30 Km coverage is possible. See Fig Abbreviations :- Fig M 1. CDMA (WLL): - Code Division Multiple Access (Wireless in Local Loop) 2. FECU : - Front End Combiner Unit. 3. LPAU-D : - Linear Power Amplifier Unit-D. 4. TSM : - Test Manager. 5. BSM : - Base Station Manager. 6. WICR : - WLL inter working Control Rack. 7. WNIR : -WLL Network Interface Rack. 8. MSIR : - Mobile Subs Interface Rack. 9. BSCR : - Base Station Control Rack. 120

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