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Basic Telecom concepts
Various Wireless Technologies
Cellular concepts & Principal of cellular Comm.
GSM Network Architecture
GSM channel Architecture
Call Flows in GSM
GSM Planning steps (Nominal Plan & RF surveys)
GSM Optimization Steps ( Performance, Drive testing & Benchmarking)

Published in: Business, Technology


  1. 1. Telecom TutorialsMonday, June 03, 2013www.tempustelcosys.comRF & GSM Concepts
  2. 2. Monday, June 03, 2013www.tempustelcosys.comBasic Telecom conceptsVarious Wireless TechnologiesCellular concepts & Principal of cellular Comm.GSM Network ArchitectureGSM channel ArchitectureCall Flows in GSMGSM Planning steps (Nominal Plan & RF surveys)GSM Optimization Steps ( Performance, Drive testing & Benchmarking)
  3. 3. Monday, June 03, 2013www.tempustelcosys.comTill 1982 Cellular Systems were exclusively Analog Radio Technology.Advanced Mobile Phone Service (AMPS)U.S. standard on the 800 MHz BandTotal Access Communication System (TACS)U.K. standard on 900 MHz bandNordic Mobile Telephone System (NMT)Scandinavian standard on the 450 & 900 MHz band
  4. 4. Monday, June 03,
  5. 5. Monday, June 03, 2013www.tempustelcosys.comGSM - 900The term GSM-900 is used for any GSM system which operates in any 900 MHz band.P-GSM - 900P-GSM-900 band is the primary band for GSM-900 Frequency band for primary GSM-900 (P-GSM-900) : 2 x 25 MHz890 – 915 MHz for MS to BTS (uplink)935 – 960 MHz for BTS to MS (downlink)E-GSM - 900In some countries, GSM-900 is allowed to operate in part or in all of the following extension band. E-GSM-900 (Extended GSM-900) band includes the primary band (P-GSM-900) and the extension band :880 – 890 MHz for MS to BTS (uplink)925 – 935 MHz for BTS to MS (downlink)R-GSM-900R-GSM-900 (Railway GSM-900) band includes the primary band (P-GSM-900) and the following extension band:876 – 890 MHz for MS to BTS (uplink)921 – 935 MHz for BTS to MS (downlink)GSM-1800Frequency band: 2 x 75 MHz1710 – 1785 MHz for MS to BTs (uplink)1805 – 1880 MHz for BTS to MS (downlink)
  6. 6. Monday, June 03, 2013www.tempustelcosys.comTelecom Service Providers/OperatorsGSMCDMABasic-WLLInternet ServicesLong DistanceVendorTelecom Consultancy
  7. 7. Monday, June 03, End of 1980‟s Analog Systems unable to meet continuing demands Severely confined spectrum allocations Interference in multipath fading environment Incompatibility among various analog systems Inability to substantially reduce the cost of mobile terminals and infrastructure required
  8. 8. Monday, June 03, 2013www.tempustelcosys.comSpectrum space - most limited and precious resourceSolution - further multiplex traffic (time domain)Can be realized with Digital Techniques only
  9. 9. Monday, June 03, 1979 Europe wide frequency band reserved for Cellular 1982 “Groupe Speciale Mobile” created within CEPT 1986 GSM had full time in Paris 1988 ETSI takes over GSM Committee 1990 The phase 1 GSM Recommendationsfrozen 1991 GSM Committee renamed “Special Mobile Group” andGSM renamed as “Global System for Mobile Communication” 1992 GSM launched for commercialoperations
  10. 10. Monday, June 03, 2013www.tempustelcosys.comService Provider is not a Equipment Manufacturer.The Service Provider has a license to operate in a geographical boundary (state/circle/ country).It buys equipment from OEM Suppliers (Vendors).Installs & commissions the equipment thus making it‟s own Network.Provides the desired service to it‟s subscribers.
  11. 11. Monday, June 03, 2013www.tempustelcosys.comVendor is a Equipment Manufacturer.It supplies Product, Consultancy and TrainingsService provider has the option of taking the Consultancy and Training
  12. 12. Monday, June 03, 2013www.tempustelcosys.comA cellular system links Mobile subscribers to PublicTelephone System or to another Mobile subscribers.It removes the fixed wiring used in a traditional telephone installation.Mobile subscriber is able to move around, perhaps can travelin a vehicle or on foot & still make & receive call.
  13. 13. Monday, June 03, 2013www.tempustelcosys.comMobilityFlexibilityConvergenceGreater QOSNetwork ExpansionRevenue/Profit
  14. 14. Monday, June 03, 2013www.tempustelcosys.comCONSIDERATIONS - FREQUENCY SUBSCRIBER DENSITY COVERAGE14Base StationBase StationBase StationBase StationBase StationBase Station
  15. 15. Monday, June 03, 2013www.tempustelcosys.comCellular Radio involves dividing a large service area into regions called “cells.”Each cell has the equipment to switch, transmit and receive calls.Cells - Reduce the need of High powered transmissionCells - Conventionally regarded as being hexagonal, but in reality they are irregularly shaped.Cell shape is determined by the nature of the surroundingarea e.g. Hills , tall building etc.
  16. 16. Monday, June 03, 2013www.tempustelcosys.comLarge Cells35 KmRemote AreasHigh Transmission PowerFew subscribersSmall CellsNear about 1 KMUrban AreasLow Transmission PowerMany Subscribers
  17. 17. Monday, June 03, 2013www.tempustelcosys.comCoveragePercentage of the geographical area covered by cellular service where mobile telephony is availableCapacity -Number of calls that can be handled in a certain area within a certain period of time.Capacity can also refer to the probability that users will be denied access to a system due to thesimple unavailability of radio channels.
  18. 18. Monday, June 03, 2013www.tempustelcosys.comDesignation Abbreviation Frequencies Free-space WavelengthsVery Low Frequency VLF 9 kHz - 30 kHz 33 km - 10 kmLow Frequency LF 30 kHz - 300 kHz 10 km - 1 kmMedium Frequency MF 300 kHz - 3 MHz 1 km - 100 mHigh Frequency HF 3 MHz - 30 MHz 100 m - 10 mVery High Frequency VHF 30 MHz - 300 MHz 10 m - 1 mUltra High Frequency UHF 300 MHz - 3 GHz 1 m - 100 mmSuper High Frequency SHF 3 GHz - 30 GHz 100 mm - 10 mmExtremely High Frequency EHF 30 GHz - 300 GHz 10 mm - 1 mm
  19. 19. Monday, June 03, 2013www.tempustelcosys.comEach Cell in the Cellular Network consists of one or more RF carriers.An RF carrier is a pair of radio frequenciesOne used in upward direction by MS - UplinkOther used in downward direction by BTS - DownlinkThe transmit and receive frequencies are separated by a gap of 45 MHz in GSM of 75 MHz in DCS.There are 124 carries in GSM Band. With each carrier carrying 7 timeslots, only124 x 7 = 868 calls can be made!Frequency Reuse is the solution
  20. 20. Monday, June 03, 2013www.tempustelcosys.comFul(n) = 890.0 + (0.2) *n MHzFdl(n) = Ful + 45 MHzwhere n =ARFCN ; 1 n 124
  21. 21. Monday, June 03, 2013www.tempustelcosys.comPowerFrequencyTimeFDMAFrequencyPower TimeTDMAFrequencyCDMAPowerTime
  22. 22. Monday, June 03, 2013www.tempustelcosys.comPowerTDMAPowerFDMAPowerCDMAFDMA: AMPS & NAMPS•Each user occupies a private Frequency,protected from interference through physicalseparation from other users on the samefrequency•TDMA: IS-136, GSM•Each user occupies a specific frequency butonly during an assigned time slot. Thefrequency is used by other users duringother time slots.•CDMA•Each user occupies a signal on a particularfrequency simultaneously with many otherusers, but is uniquely distinguishable bycorrelation with a special code used only bythis user
  23. 23. Monday, June 03, 2013www.tempustelcosys.comThree types of frequency reusepatterns7 Cell reuse pattern4 cell reuse pattern3 cell reuse pattern
  24. 24. Monday, June 03, 2013www.tempustelcosys.comc2c1c3a1a2a3b1b2b3c1c2c3Cell Re-use
  25. 25. Monday, June 03, 2013www.tempustelcosys.comFrequency Re-useCell Dia = R7/21 cell cluster1234567D D=R (3N)where N is Cluster size
  26. 26. Monday, June 03, 2013www.tempustelcosys.comOmni Directional Cells120 degree Sectors60 Degree sectorsEach Sector in a Site has its own allocation of Radio CarriersAdvantageBy frequent reuse of frequency more capacity can be achieved
  27. 27. Monday, June 03, Multipath Fading results in variations in signal strength which is known as RaleighFading. Raleigh Fading phenomenon is dependent on path difference and hencefrequency of reception. A fast moving mobile may not experience severe effect of this fading since thepath difference is continuously changing. A slow moving mobile ( or a halted mobile ) may experience severe deterioration inquality. But, if the frequency of reception is changed when this problem occurs ,couldsolve it. The fading phenomenon is fast and almost continuos, this means the frequencychange should also be continuos. This process of continuously changing frequency is known as Frequency Hopping.
  28. 28. Monday, June 03, 2013www.tempustelcosys.comReduction in Average Interference With Frequency Hopping consistent interference will become bursty. So even though, both the co-channel cells will be using the same set of ARFCNs for Hopping,interference will not be continuos. This is because, GSM cells are not Frame synchronized, and change in frequency is related to Framenos. If same HSN is used in two cells, then either the interference will be nil , or if a phase correlation existsthen it will be continuos. So the two cells should preferably use different HSNs . Sectorial cells ( controlled by the same BTS) can use same HSN, since the sectors dont come up at thesame time. Cells if they are synchronized, can use same HSN, if each cell has an offset of some TDMA frames. Offset of TDMA frames is also required to avoid SACCH occurring at the same time in all synchronizedcells, as they kills away the objective of DTX.
  29. 29. Monday, June 03, 2013www.tempustelcosys.coma1a2a3a3a4a6a5OMNI CELL1 ANTENNAb1b2b3120O CELLS3 ANTENNAS60O CELLS6 ANTENNAS
  30. 30. Monday, June 03, Compatibility Noise Robust Increased Capacity & Flexibility Use of Standard Open Interfaces Improved Security & Confidentiality Cleaner Handovers Subscriber Identification ISDN Compatibility Enhanced Range of Services
  31. 31. Monday, June 03, 2013www.tempustelcosys.comHard HandoffAnalog, TDMA and GSMSoft HandoffCDMABreak before Make Make before Break
  32. 32. Monday, June 03, 2013www.tempustelcosys.com1201811982001324144246975113287173708078111213 161718192022253240171173175182187197199201213214215216218219220221222225
  33. 33. Monday, June 03, 2013www.tempustelcosys.comThe mobile measures up to 32 adjacent cells forSignal Strength (RxLevel)Signal Quality (RxQual)updated every 480 mS and sends to BTSSophisticated Handover based onRxLevelInterferenceRxQualTiming AdvancePower Budget
  35. 35. Monday, June 03, 2013www.tempustelcosys.comMSISDN : Human Identity used to call a Mobile StationIMEI: Serial number unique to every Mobile StationIMSI : Network Identity unique to a SIM3 digits 2 digits 10digits TMSI : Identity unique in a LAIMSRN : Mobile Station Roaming NoCC NDC SN98 XXX 12345MCC MNC MSIN404 XX 12345TAC FAC SNR S6 digits 2 digits 6 digits 1 digit
  36. 36. Monday, June 03, 2013www.tempustelcosys.comMobile Station consists of two parts-Mobile Equipment (ME)Subscriber Identity Module (SIM)MEHardware e.g. Telephone, Fax Machine, Computer.SIMSmart Card which plugs into the ME.
  37. 37. Monday, June 03, Revision Level Phase of the GSM specs ME comply with. RF Power Capability Max power ME is able to Transmit. Ciphering Algorithm Used Presently A5 Phase 2 specifies Algorithms A5/0 to A5/7. Frequency Capability SMS Capability
  38. 38. Monday, June 03, 2013www.tempustelcosys.comClass PowerO/p1 20 W2 8 W3 5 W4 2 W5 0.8 WTypicalSettings
  39. 39. Monday, June 03, 2013www.tempustelcosys.comIMSI(International Mobile Subscriber Identity)Transmitted over Air Interface on initializationPermanently stored on SIM card15 digit Decimal
  40. 40. Monday, June 03, MSISDN 10 digit number to which a subscriber is being called. PIN (Personal Identification Number) Four digit PIN An internal security to Protect the SIM from illegal use. Card blocks itself after three wrong entries PUK (Personal Unblocking Key) 8 digit code to unblock the SIM Card Ki (Authentication Key), A3 & A8 Algorithms
  41. 41. Monday, June 03, Temporary Mobile Subscriber Identity Periodically changed by the System Management on instances like location update etc. Reason for use of TMSI To prevent a possible intruder from identifying GSM users, TMSI is used Management Assignment, Administration & Updating is performed by VLR.
  42. 42. Monday, June 03, 2013www.tempustelcosys.comConverts 64 Kbps PCM circuits from MSC to 16 Kbps BSS circuits.Each 30 channel 2 Mbps PCM link can carry 120 GSM - specified voicechannels.
  43. 43. Monday, June 03, 2013www.tempustelcosys.comBSS (Base StationSystem)BSC (Base Site Controller)BTS (Base TransceiverStation)XCDR (Transcoder)NetworkSwitchingSystem(NSS)XCDRBSCBTS
  44. 44. Monday, June 03, 2013www.tempustelcosys.comBSCControls upto 40 BTSConveys information to/from BTSConnects terrestrial circuits & Air Interface ChannelsControls handovers between BTSs under itselfBTSContains RF HardwareLimited control functionality1 - 6 carriers in a BTS Cabinet7 - 48 simultaneous calls per BTS
  45. 45. Monday, June 03, 2013www.tempustelcosys.comCollocated BTSRemote BTSStar ConfigurationDaisy Chain BTSBSCBTSBTSBTSAllBTSon1E1BSCBTSBTSBTSBTS
  46. 46. Monday, June 03, 2013www.tempustelcosys.comNSS (Network Switching System)MSC (Mobile Switching Centre)HLR (Home Location Register)VLR (Visitor Location Register)EIR (Equipment Identity Register)AUC (Authentication Centre)IWF (Interworking Function)EC (Echo Canceller)
  47. 47. Monday, June 03, 2013www.tempustelcosys.comMSCCall SwitchingOperation & Management SupportInternetwork InterworkingCollects call billing dataGateway MSCMSC which provides interface between PSTN & BSS‟s in the GSM Network.
  48. 48. Monday, June 03, 2013www.tempustelcosys.comReference database for the Subscriber profiles-Subscriber ID (IMSI & MSISDN)Current VLR AddressSupplementary Services subscribedSupplementary Service InformationSubscriber Status (Registered/deregistered)Authentication Key and AUC functionalityTMSIMSRN
  49. 49. Monday, June 03, 2013www.tempustelcosys.comTemporary Data, which exists as long as the subscriber isactive in a particular Coverage area.Contains the following-Mobile Status (Busy/ Free/ No Answer/etc.)Location Area Identity (LAI)TMSIMSRN (Mobile Station Roaming Number)
  50. 50. Monday, June 03, 2013www.tempustelcosys.comContains Database for validating IMEIWhite List (valid ME)Black List (Stolen ME)Grey List (Faulty ME)
  51. 51. Monday, June 03, 2013www.tempustelcosys.comProvides function to enable the GSM System to interface with Public/Private Data Networks.The basic feature of the IWF areRate ConversionProtocol adaptationIWF incorporates Modem Bank.e.g. GSM DTE PSTN DTEIWF Analogue Modem
  52. 52. Monday, June 03, Echo is apparent only in Mobile - Land conversation & is generatedat the 2 wire to 4 wire interface. To avoid it, Echo Canceller (EC) is used. Echo is irritating to MS Subscriber Total Round Trip delay of 180 ms in the GSM system EC is placed on the PSTN side of the Switch Cancellation up to 68 ms with EC
  53. 53. Monday, June 03, 2013www.tempustelcosys.comEvent & Alarm ManagementFault ManagementPerformance ManagementConfiguration ManagementSecurity Management
  54. 54. Monday, June 03, 2013www.tempustelcosys.comBroadly classified into two types of interfaces-Standard Interfaces2 Mbps Trunks (E1)Signalling System No. 7 SS7 ( CCS7)X.25 (Packet Switched Mode)GSM Interfaces
  55. 55. Monday, June 03, 2013www.tempustelcosys.comUm MS - BTSAbis BTS - BSCA BSC - MSCB MSC - VLRC MSC - HLRD VLR - HLRE MSC - MSCF MSC - EIRG VLR - VLRH HLR - AUC
  56. 56. Monday, June 03, 2013www.tempustelcosys.comGSM protocols are basically divided into three layers:Layer 1: Physical layerEnables physical transmission (TDMA, FDMA, etc.)Assessment of channel qualityExcept on the air interface (GSM Rec. 04.04), PCM 30 or ISDNlinks are used (GSM Rec. 08.54 on Abis interface and 08.04 onA to F interfaces).Layer 2: Data link layerMultiplexing of one or more layer 2 connectionson control/signaling channelsError detection (based on HDLC)Flow controlTransmission quality assuranceRoutingLayer 3: Network layerConnection management (air interface)Management of location dataSubscriber identificationManagement of added services (SMS, call forwarding, conferencecalls, etc.)
  59. 59. Monday, June 03, 2013www.tempustelcosys.comData protection is required onair interface.A specific key called CipheringKey (Kc), is generated fromRAND and A8 algorithm.A8 is on the SIM.A8RANDKiKc
  60. 60. Monday, June 03, 2013www.tempustelcosys.comA5DataKcCipheredDataA5KcData
  61. 61. Monday, June 03, 2013www.tempustelcosys.comAccess NetworkMicrowave 15 /23 GHzBackbone NetworkMicrowave 7 GHzOptical FibersLeased Line( From Dot or any other service provider on any media)
  62. 62. Monday, June 03, 2013www.tempustelcosys.comDifferent Possible CombinationsMono Mode Step Index 10 / 125 mMono Mode Graded indexMulti Mode Step Index 100 / 300 mMulti Mode Graded Index 75 / 130 mMono Mode Graded Index would have been the best but fabrication not possible140 Mbps OLTE , Mono Mode Step Index in our case
  63. 63. Monday, June 03,
  64. 64. Monday, June 03, 2013www.tempustelcosys.comPhysical ChannelLogical ChannelPhysical ChannelPhysical channel is the medium over which the information is carried.Logical ChannelLogical channels consists of the information carried over the Physical Channel.
  65. 65. Monday, June 03, 2013www.tempustelcosys.com0 1 2 3 4 5 6 7357encrypted57encrypted26training1S1S3T8.25GP3T577 S577 S x 8 = 4.615mSTDMA FrameNormal Burst26 Frame Multi-frame
  66. 66. Monday, June 03,
  67. 67. Monday, June 03, Time is divided into discrete periods called“Timeslots”• TCH carries payload data - speech, fax, data• Connection may be:- Circuit Switched - voice or data or- Packet Switched – data• TCH may be:• Full Rate (TCH/F)- one channel per user- 13 kb/s voice, 9.6 kb/s data or• Half Rate (TCH/H)- one channel shared between two users- 6.5 kb/s voice, 4.8 kb/s dataTraffic ChannelsTCH/FFull rate 22.8kbits/sTCH/HHalf rate 11.4 kbits/s
  68. 68. Monday, June 03, 2013www.tempustelcosys.comDCCH(Dedicated Channels)Downlink & UplinkCCCH(Common Control Chan)Downlink & UplinkSynch.ChannelsRACHRandomAccess ChannelCBCHCell BroadcastChannelSDCCHStandalonededicatedcontrol channelACCHAssociatedControl ChannelsSACCHSlow associatedControl ChannelFACCHFast AssociatedControl ChannelPCH/AGCHPaging/Access grantFCCHFrequencyCorrection channelControl ChannelsBCH ( Broadcast channels )Downlink onlyBCCHBroadcastcontrol channelSCHSynchronizationchannel
  69. 69. Monday, June 03, 2013www.tempustelcosys.comBCH channels are all downlink and are allocated to timeslot zero.Channels are:• FCCH: Frequency control channel sends the mobile a burst of all „0‟bits which allows it to fine tune to the downlink frequency• SCH: Synchronization channel sends the absolute value of the frame number (FN), which is theinternal clock of the BTS, together with the Base Station Identity Code (BSIC)• BCCH: Broadcast Control Channel sends radio resourcemanagement and control messages, Location Area Code and so on.Some messages go to all mobiles, others just to those that are in theidle state
  70. 70. Monday, June 03,•CCCH contains all point to multi-point downlink channels (BTS toseveral MSs) and the uplink Random Access Channel:• CBCH: Cell Broadcast Channel is an optional channel for generalinformation such as road traffic reports sent in the form of SMS• PCH: Paging Channel sends paging signal to inform mobile of a call• RACH: Random Access Channel is sent by the MS to request achannel from the BTS or accept a handover to another BTS.A channel request is sent in response to a PCH message.• AGCH: Access Grant Channel allocates a dedicated channel(SDCCH) to the mobile• NCH: Notification Channel informs MS about incoming group orbroadcast calls
  71. 71. Monday, June 03, 2013www.tempustelcosys.comSDCCH( Standalone Dedicated Control Channel )Uplink and DownlinkUsed for call setup, location update and SMS.SACCH( Slow Associated Control Channel )Used on Uplink and Downlink only in dedicated mode.Uplink SACCH messages - Measurement reports.Downlink SACCH messages - control info.FACCH( Fast Associated Control Channel )Uplink and Downlink.Associated with TCH only.
  72. 72. Monday, June 03, 2013www.tempustelcosys.comThe Time Slots are arranged in a sequence , conventionally numbered 0 to 7.Each repetition of this sequence is called a TDMA Frame.The information content carried in one time slot is called a “burst”.
  73. 73. Monday, June 03, Information Main Area where the Speech, Data or Control info is held Guard Period To enable the burst to hit the time slot (0.031ms) Stealing Flags 2 bits are set when TCH is to stolen by a FACCH Training Sequence For estimation of transfer characteristics of physical media Tail Bits Used to indicate beginning and end of the burst.
  74. 74. Monday, June 03, 2013www.tempustelcosys.com0 1 2 3 4 5 6 7 2 4 5 6 730 1FRAME 1 FRAME 2Training SequenceInformation InformationGUARDPERIODGUARDPERIODTAIL BITS TAIL BITS
  75. 75. Monday, June 03, Normal BurstTraffic & Control Channels Bi-directional Frequency Correction BurstFCCH Downlink Synchronization BurstSCH Downlink Dummy BurstBCCH Carrier Downlink Access BurstRACH Uplink
  76. 76. Monday, June 03, 2013www.tempustelcosys.comMobile to MobileIntra-cityInter-cityMobile to LandIntra-cityInter-cityLand to MobileIntra-cityInter-city
  79. 79. Monday, June 03,• Calling Line Identification– Present– Absent• Connect Line Identification– Present– Absent• Closed User Group - CUG– Only incoming– Only outgoing• Operator Controlled Barring
  80. 80. Monday, June 03,Data rates supported as of today are 2.4 Kbps 4.8 Kbps 9.6 Kbps GPRS & EDGE implementation takes the data capability to higher level of the order of 184kbps and more
  81. 81. Monday, June 03,• Good coverage – where ever he goes• Good quality• No blocking• Value added services– SMS– Voice mail– MMS– Call forward/call waiting– Data/internet at high data rates– prepaid
  82. 82. Monday, June 03, 2013www.tempustelcosys.comThe basic objectives of a wireless system are:– COVERAGE: provide sufficient cell sites to deliver RF coverage of the entire desired area.– BUILDING/VEHICLE PENETRATION: deliver sufficient signal levels to adequately penetratebuildings and vehicles where appropriate.– TRAFFIC: ensure that no cell captures more traffic than it can handle at the desired grade ofservice (i.e., blocking percentage)– PERFORMANCE: design, construct, and adjust the network to deliver reliable service freefrom excessive origination and call delivery failures, dropped calls, quality impairments, andservice outages.– ECONOMICS: provide return on investment sufficient to support operating and capitalexpenses, expand the network to take advantage of growth opportunities, and retire costs ofconstruction prior to depreciation of the network equipment
  83. 83. Monday, June 03, 2013www.tempustelcosys.comInputs– Coverage objectives• Area coverage objectives• Coverage penetration objectives– Morphology data/clutter information– Terrain data and Vector maps– Traffic objectives• Number of subscribers defined• Traffic per subscriber defined• Desired grade of service defined– City regulations– BTS Hardware specifications– Link Budget– Business and Logistical objectives• Capital budget• Timing: launch data• Operating revenue Vs. total costs• Output– Cell database and traffic model– Composite coverage plot– Equal power handoff boundaries plot
  84. 84. Monday, June 03,• Site acquisition– Availability of suitable candidate (building or land)– Owner interest– Cost of leasing– Frequency clearance (SACFA)– Government authority approval– Space constraints and other construction issues• Candidate Location – line of sight to the objective• Clutter type• Terrain variations• Physical Blocking – buildings, hoardings• Water• Mumbai – High end, high traffic areas are very close to water….Makes RF design much more challenging• Deviation from desired location impacts surrounding site locations
  85. 85. Monday, June 03,• Understand geographical area as per license agreement• Define coverage expectations in terms– On road coverage– In-building coverage (different penetration margins)• Capacity considerations – busy hour per subscriber call attempts and minutes of use(Erlangs)• 1 Erlang is 1 call of 1 hour duration• Decide number of sites based on coverage capacity requirement• Propagation tools used for this analysis• Finalize exact site locations after field survey• Initiate candidate identification process• Site acquisition/antenna positioning• Modify existing design if site location changes
  86. 86. Monday, June 03, 2013www.tempustelcosys.comTraffic &GrowthAnalysisSystemOptimisationSite CoverageConfirmationSite Search &SelectionPropagationmodelverificationSystem/SiteDimensioningRF &NetworkPlanningMarketRequirementSite AcquisitionSite BuildOperationalNetworkSite SearchPlanPerformanceMonitoring
  87. 87. Monday, June 03, Various steps are listed below CW survey Model Tuning Nominal Planning RF site Surveys Realized Planning Frequency Planning Implementation Optimization Drive Testing Performance Analysis
  88. 88. Monday, June 03, 2013www.tempustelcosys.comIt consists of planning a set of sites on planning tool so as to predict the coverage of the target areaTool needs to be made intelligent so as to predict the coverage as close as possible to actual coverageCoverage plots are based on customer intension of providing indoor and outdoor coverage
  89. 89. Monday, June 03,
  90. 90. Monday, June 03, 2013www.tempustelcosys.comColabaMalabar HillMazgaon>=30dB:: 3-4 wall coverage25-30dB : 3 Wall Coverage23-25 dB : 2-3 Wall Coverage18-23dB: 2-3 Wall Coverage16-18 dB : 2 Wall Coverage8-16dB : 1-2wall Coverage08 dB : On Road-1 Wall Coverage00 dB : On Road/No CoverageIndoor Coverage:Penetration Margin Legend
  91. 91. Monday, June 03,• Propagation models are used to predictcoverage from a particular site• A composite coverage plot shows theoverall coverage produced by each sectorin the field of view• The color of each pixel corresponds to thesignal level of the strongest server at thatpoint• Such plots are useful for identifyingcoverage holes and overall coverageextent
  92. 92. Monday, June 03, 2013www.tempustelcosys.comClutter typesDense UrbanUrbanSub UrbanRuralWaterVegetationIndustrialForest
  93. 93. Monday, June 03, 2013www.tempustelcosys.comEach nominal has a search ring defined by the RF PlannerCandidates needs to be identified as close as possible to the nominal within the search ringHeight, orientations & antenna placement at site are the key RF parameter which are based upon thecoverage requirement in the areaMajor obstructions and clutter type in various directions to be observed on RF survey
  94. 94. Monday, June 03, 2013www.tempustelcosys.comEquipment required for RF SurveyGPSDigital CameraBinocularsMagnetic CompassThere might be 3 or more candidates surveys for one siteEach candidate would have an RF survey form and panoramicassociated with it
  95. 95. Monday, June 03,•Drive testing is an important activity to get statistics & graphs on coverage, quality &capacity in the downlink direction• Drive test setup – DT tool, Engineering Handset, GPS,accessories• Call in 2 modes• Dedicated – while the mobile is on call• Idle – while the mobile is idleImportant parameters observed during drive testing• Coverage – Rx level (Full & Sub)• Quality – RxQual & SQI• Handover, Dropped call, Neighbor list, TA
  96. 96. Monday, June 03,• Parameters of propagationmodels must be adjusted for bestfit to actual drive-test measureddata in the area where the modelis applied• The figure at right shows drive-test signal strengths obtainedusing a test transmitter at anactual test site• Tools automate the process ofcomparing the measured datawith its own predictions, andderiving error statistics• Prediction model parametersthen can be “tuned” to minimizeobserved error
  97. 97. Monday, June 03,• The words “performance optimization” mean different things to different people, viewedfrom the perspective of their own jobs• System Performance Optimization includes many different smaller processes at manypoints during a system’s life– recognizing and resolving system-design-related issues (can’t build a crucial site, toomuch overlap/soft handoff, coverage holes, etc.)– “cluster testing” and “cell integration” to ensure that new base station hardware worksand that call processing is normal– “fine-tuning” system parameters to wring out the best possible call performance– identifying causes of specific problems and customer complaints, and fixing them– carefully watching system traffic growth and the problems it causes - implementingshort-term fixes to ease “hot spots”, and recognizing problems before they becomecritical
  98. 98. Monday, June 03, 2013www.tempustelcosys.comOptimisation is an ongoing process of analysing network performanceagainst Quality of Service targets:
  99. 99. Monday, June 03,•Measurements of network performance cover:• Traffic in erlangs• TCH and SDCCH Grade of Service (Congestion)• Call success rate• Handover failure• Coverage area• Coverage quality• Subscriber base and growth• Key Performance Indicators (KPI) are measurable dynamicparameters that help to target areas of concern
  100. 100. Monday, June 03, 2013www.tempustelcosys.comAppropriate KPIs to use depend on:• The nature of the network• Data sources available• Measurement tools available• Ability of engineering team• Cost of network infrastructure• Sources of data include:• Surveyed data - from drive tests• Network statistics - from OMC• Field engineer reports
  101. 101. Monday, June 03, 2013www.tempustelcosys.comTransmission TimingPower ControlVAD Voice Activity Detector and DTXMultipath FadingEqualizationDiversityFrequency HoppingAntenna Parameters ( Height, Azimuth, Tilts )
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  104. 104. Monday, June 03,•Surveyed data from test-mobile measurements can be used tobenchmark system performance against that of a competitor• Problems that may be identified from surveyed data:• Poor coverage• Unexpected interference• Missing handover definitions• Installation problems at BTS• Test-mobile measurements should include:• continuous calls to test coverage• repetitive short calls to test call-success
  105. 105. Monday, June 03, 2013www.tempustelcosys.comRF Planning ToolDrive Test ToolOptimization ToolMapInfo