INTERVIEW

INTERVIEW3GAtunu GoraiWCDMA Frequency and SpectrumUplink=1920MHz -1980 MHzDownlink= 2110MHz -2170MHzBandwidth=60 MHz Actual B.W assign to operator is 5MHz & out of that 3.84MHz is utilize. In WCDMA frequency reuse factor =1 because time and frequency remains constant.

Eb /NO= Bit energy/Noise energyEc/No = Chip Energy /Noise Energy.

Ec/No= Eb/No - process gainAs per Eb/No is fixed for each service for Ex: voice =2 and video=4Ec/N0= 2- 10= -8 for voice(for voice -8 is good limit)Ec/N0= 4-18= -14 for video(for video -14 is good limit)

Process gain(voice) = chip rate/bit rate= 10dBProcess gain (video) = chip rate /bit rate= 18dBChip rate = 3.84Mchips in WCDMA.

Cyclic Redundancy Check (CRC) is used to detect if there are anyuncorrected errors left after error correction

The next part in the transmitter is Forward Error Correction (FEC).The function of this block is to help the receiver correct bit errorscaused by the air interface.The error-protected signal is then multiplied by a particularchannelization code to provide the necessary channel separation.This is necessary since all the channels will be added together,which will produce a composite data stream.

Channelization codesIn the downlink, the channelization codes are used to separate thedifferent data channels coming from each cell. For the dedicatedchannels, this represents the different users since only onescrambling code is used for all downlink transmission from thecell.

In the uplink, the channelization codes are used to separate thedifferent data channels sent from the UE to the each cell. Theseparation of the different UEs will here be done with differentscrambling codes.

The number of codes used in the downlink is restricted to 8192 intotal. This is done to speed up the process for the UE to find thecorrect scrambling code. 512 of these are primary codes (the restare secondary codes, 15 codes per primary) divided into 64 codegroups each group containing 8 different codes. The UE candetermine which scrambling code group a cell is using by thesynchronization procedure (see chapter 5). Note that there are norestrictions for the number of codes generated by the 24 bits startkey in the uplink caseData Drive There is 3 modulation technique QPSK,16QAM,64QAM.For high through put 16QAM and 64QAM should have high UtilizationSo, if There is less Utilization of QPSK in downlink than data throughput is also highCQI is like SQI in speech which ensure good channel quality for data transfer.Retransmission of HS- DSCH(High-Speed Downlink Shared Channel) packet is high than also throughput is decreases.In case of stationary Data Test- 2Mbits speed can be achieved In case of moving Vehicle 800kbits to 1.2 Kbits speed can be achieved.Application throughput is always 85% of physical layer data rate throughput because at application level IP inclusion and overhead information will be there.Latency time is round trip time from server and for 3G it should be 150 ms for 32 bit data .

The modulation scheme and coding is changed on a per-user basis depending on signal quality and cell usage. The initial scheme is Quadrature phase-shift keying (QPSK), but in good radio conditions 16QAM and 64QAM can significantly increase data throughput rates. With 5 Code allocation, QPSK typically offers up to 1.8Mbit/s peak data rates, while 16QAM offers up to 3.6 Mbit/s. Additional codes (e.g. 10, 15) can also be used to improve these data rates or extend the network capacity throughput significantly.Data Throughput will be also depend on MS class which support 5,10 and 15 codes resp.CQI- Channel quality indication may include carrier level received signal strength indication (RSSI) and bit error rate (BER). IChannel quality indicators are messages that are sent on a communication system (such as a mobile communication system) that provide the remote connection (e.g. base station) with channel quality information

Notes on quantities denoting signal powerKEY PERFORMANCE INDICATORSAccessability (Call set-up success rate)Retainability (Dropped calls)Mobility (Handover success rate)Integrity (BLER and throughput)Integrity- qualityIntegrity-throughputWhat is the major difference in link budgets between UMTS and GSM/TDMA?In UMTS yougenerallyhave a link budget for each service (voice, data, video etc), in GSM you usually only use 1 for voice. Each service has a different Eb/No target. In UMTS you have to consider the target traffic load you will have and add a noise-rise margin, in GSM you may have a slight interference margin but not normally related to traffic. In UMTS some services (like voice) will show up as uplink limited butother services(like HSDPA, 384kbps service) will show as downlink limited. In UMTS you usually have to consider that all users use the same power from the BTS therefore the morenumberof users the lowerthe maximumpower available per user (maximum power per connection) which is a starting pointin the linkbudget.

KPIRequirementsFormulaCPICH RSCP-95dBmN/A(nbr_of_samples_RSCP>=-95dBm)/(tot_nbr_of_samples_RSCP)CPICH Ec/Io-12dBN/A(nbr_of_samples_EcIo>=-12dB)/(tot_nbr_of_samples_EcIo)Voice call setup success rateMin %98%(nbr_of_successful_voice_call_setup)/(nbr_of_voice_call_attemp)Voice call setup time(Mobile to 1764440)10s99%(nbr_of_voice_call_setup_time10s)/(nbr_of_successful_voice_call_setup)voice_call_setup_time =[T(CC_alerting) - T(first_RRC_connection_request)]9s95%(nbr_of_voice_call_setup_time9s)/(nbr_of_successful_voice_call_setup)voice_call_setup_time =[T(CC_alerting) - T(first_RRC_connection_request)]Voice call drop rateMax %2%(nbr_of_voice_call_drop)/[(call_duration_time)/90sec]PDP activation successful rateMin %99%(nbr_of_PDP_context_activation_accept)/(nbr_of_PDP_context_activation_request)PDP activation delay2s99%(nbr_of_PDP_activation_delay2s)/(nbr_of_PDP_context_activation_accept)PDP_activation_delay= [T(PDP_context_activation_accept)- T(PDP_context_activation_request)]PS 384k FTP DLAvg Throughput280kbps(downloaded_data_kbit)/(data_session_duration)PS 384k FTP ULAvg Throughput280kbps(uploaded_data_kbit)/(data_session_duration)HSDPA FTPAvg Throughput4.5Mbps(downloaded_data_kbit)/(data_session_duration)HSUPA FTPAvg Throughput1.1Mbps(uploaded_data_kbit)/(data_session_duration)KPI calculationCase 1: Drop due to missing neighborProblem: Detected Nighbor (DN)UE sends a Measurement Report that contains an event1a means adding a new RL (cell) to Active SetIf the reported cell is not in the current neighbor cell list and the reported Ec/No is better than the best serving cell Ec/No in AS by some dBs (set by a RNC parameter)If for any reason the new cell can not be added to AS, call will be releasedIf the UE reconnects to the network immediately after call drop and the scramble of the cell that UE camps on is different from that upon call drop, missing neighbor cell is probable. Confirm it by measurement control (search the messages back from call drop for the latest intra-frequency measurement control message. Check the neighbor cell list of this measurement control message)

UEs might report detected set information. If corresponding scramblling code information is in the monitor set before call drop, the cause must be missing neighbor cell.

11Weak Coverage Weak coverage usually refers to weak RSCP

Uplink or downlink DCH power helps to confirm the weak coverage is in uplink or downlink by the following methods.

If the uplink transmission power reaches the maximum before call drop, the uplink BLER is weak ,the call drop is probably due to weak uplink coverage.

Out of Uplink coverage may be caused by not only by low CPICH_RSCP But also by high UL_RSSI

If the downlink transmission power reaches the maximum before call drop and the downlink BLER is weak, the call drop is probably due to weak downlink coverage High downlink RSSI received by UE is an indication of weak coverage during that time UE tries to increase its target SIR to listen to the network.

Multipath propagation yields signal paths of different lengths withdifferent times of arrival at the receiver. Typical values of timedelays (s) are 0.2 in Open environment, 0.5 Suburban and 3 inUrban.

When coded data rates of services are incompatible,Rate Matching is used to equalize the data rates. Rate Matching may be performed by: Padding with extra bits Puncturing of bits using a pseudo-random algorithmCase 2: Drop due to Poor Coverage (low RSCP)Problem: Poor DL coverageWhen UE gets to an area with low RSCP ( < -105 dBm)regardless Ec/No values there is high risk for drop.UE will likely ramp up the transmitted power and reach its max power. The UL BLER will probably increase and SIR target cannot maintain anymore, finally the call drops. Explain the concept of Cell Breathing. How is the accounted forin the linkBudget?Ans: Io or No (the interference part of Ec/Io and Eb/No) increase as the traffic on the network increases since everyone is using the same frequency. Therefore as Io or No increases the UE or BTS needs to usemore powerto maintain the same Eb/No or Ec/Io. When the power required is more thanthe maximumpower allowed,the connectioncannot be made. Users at the cell edge are usually the first to lose service, hence the service area of a cell shrinks. As traffic decreases the reverse happens and the service area increases. They should say that it is accounted for in the Noise Rise Margin foundin the LinkBudget.

13Interference In downlink, when the active set CPICH RSCP is greater than 85 dBm and the active set Ec/Io is >= 12 dB, the call drop is probably due to downlink interference Downlink interference usually refers to pilot pollution

Interference in Uplink is detected when the Uplink RTWP exceeds a certain configurable Threshold. In general Expected level of RTWP is formed by sum of the the following components. 1.Thermal noise floor (KTB =-108.132dBm) 2.Node B noise figure (Typically 1.8 dB for our equipment) 3.Noise raise due to load (50% load in Uplink corresponds to 3 db) 4.Compensation for inaccuracies in Radio N/W algoriths (2dB)WHAT IS THE PILOT POLLUTION ?Area where the SIR (Signal interference ratio) is too low and below the expected value (Ec/Io >= -12 dB), there is too much interference => the mobile cannot understand the pilot channel

HOW TO REDUCE THE PILOT POLLUTION PROBLEM ?Maximise the signal inside the best server Minimise the energy overshoot from the neighbor cells with some RF consideration (tilt, azimuth,)

Pilot PollutionExcessive strong pilots exist at a point, but no one is strong enough to be primary pilot.

1. Definition of strong pilot (CPICH_RSCP > ThRSCP)

2. Definition of Excessive CPICH_Number > ThN

3. Definition of "no best server strong enough CPICH_RSCP1st-CPICH_RSCP(ThN+1)th < ThRSCP_Relative

Following is the case from cluster Mongkok West Probable Solution : adjust engineering parameters of an antenna so that a best server forms around the antenna. For handover problems caused by pilot pollution, adjust engineering parameters of other antennas so that signals from other antennas becomes weaker and the number of pilots drops For this case reduce antenna height of site SGI.

Manydefinitions:A cellthat has a highsignal strengthat a location but is not part of the active set.A cellthat meets thecriteriafor addition into the Active Set but can not enter because the active set is full.

1.UE fails to receive active set update command (Delayed Handover)

After UE reports measurement message, the Ec/Io of original cell signals decreases sharply. When the RNC sends active set update message, the UE powers off the transmitter due to asynchronization. The UE cannot receive active set update message.This may be due to, Ec/Io of original cell decreases sharply and that of the target cell increases greatly (Turnings)

2. The best server changes frequently. Two or more cells alternate to be the best server. The RSCP of the best server is strong. The period for each cell to be the best server is short.

Probable solution: Lower the triggering time for event 1a adjust antennas to expand the handover area

adjust the antenna to form a best serverreduce Ping-pong handover by setting the handover parameter of 1B event

17Radio Interface Protocol ArchitectureRadioInterfaceProtocolArchitectureTransport Channel (SAP)Physical ChannelsLogical Channel

Packet Data Convergence Protocol:Is only for PS domain services.18Radio Interface protocol architectureL2/MACL2/RLCL1 RLCMACL3RRCPHYTransportChannelsLogicalChannelsC-plane signallingU-plane informationGCNt DC RLC RLC RLCGCNTDCRRCRLCMACGeneral ControlNotificationDedicated ControlRadio Resource ControlRadio Link ControlMedium Access ControlUTRA Protocol Architecture19Logical Channel Structure

(TDD)(ODMA)(ODMA)(TDD)20Channels

Transport Channels:

Dedicated Transport Channel (DCH), UL/DL, mapped to DCCH and DTCHBroadcast Channel (BCH), DL, mapped to BCCHForward Access Channel (FACH), DL, mapped to BCCH, CCCH, CTCH, DCCH and DTCHPaging Channel (PCH), DL, mapped to PCCHRandom Access Channel (RACH), UL, mapped to CCCH, DCCH and DTCHUplink Common Packet Channel (CPCH), UL, mapped to DCCH and DTCHDownlink Shared Channel (DSCH), DL, mapped to DCCH and DTCH

The speech service in UMTS will employ the AdaptiveMulti - rate technique. This is a single integrated codec with eight source rates:12.2, 10.2, 7.95, 7.40, 6.70, 5.90, 5.15 and 4.75 kbps. Tofacilitate interoperability with existing cellular networkssome of the modes are the same as in existing networks.

21ChannelsPhysical Channels:

Primary Common Control Physical Channel (PCCPCH), mapped to BCHSecondary Common Control Physical Channel (SCCPCH), mapped to FACH, PCHPhysical Random Access Channel (PRACH), mapped to RACHDedicated Physical Data Channel (DPDCH), mapped to DCHDedicated Physical Control Channel (DPCCH), mapped to DCHPhysical Downlink Shared Channel (PDSCH), mapped to DSCHPhysical Common Packet Channel (PCPCH), mapped to CPCHSynchronisation Channel (SCH)Common Pilot Channel (CPICH)Acquisition Indicator Channel (AICH)Paging Indication Channel (PICH)CPCH Status Indication Channel (CSICH)Collision Detection/Channel Assignment Indication Channel (CD/CA-ICH)

AMRThe bit rate of the AMR speech connection is controlled by theradio access network depending on the air interface loading and thequality of the speech connections. During high loading, such asduring busy hours it is possible to use lower AMR bit rates to offerhigher capacity while providing slightly lower speech quality. Alsoif the mobile is running out of the cell coverage area and using itsmaximum transmission power a lower AMR bit rate can be used toextend the cell coverage area.

Adaptive multi-rate also contains error concealment. The purposeof frame substitution is to conceal the effect of lost speech frames.If several frames are lost muting is used to prevent possiblyannoying sounds as a result of the frame substitution.In P5, with AMR NB it is possible to use lower speech codec ratesthan 12.2 kbps. The radio network also supports 7.95 kbps, 5.9kbps and 4.75 kbps AMR codecs. There is no adaptation in thesense that AMR codecs are changed during an ongoing speechconnection; rather there is a possibility to adapt the rate at initialselection.23Link BudgetCell range & cell capacity are limited by the same parameters:Interference in uplinkPower in downlink

Cell breathing phenomenonPower Link BudgetTx power + All Gains Path Loss Other losses = Rx power

Path loss = Tx Signal + All Gains Other losses Rx power

Max Path loss = Tx Signal + All Gains Other losses Rx sensitivity

25Initial Cell SearchThe initial Cell Search is carried out in three steps:Step 1: Slot synchronisation - using the primary synchronisation channel.Step 2: Frame synchronisation and code-group identification- using the secondary synchronisation channel.Step 3: Scrambling-code identification-identified through symbol- by-symbol correlation over the primary CCPCH with all the scrambling codes within the code group.26Slot Synchronization

P-SCH1P-SCH3P-SCH2P-SCH1S-SCH1P-CCPCHP-CCPCHP-SCH2S-SCH2P-CCPCHP-CCPCHP-SCH3S-SCH3P-CCPCHP-CCPCHP-CCPCH1 Slot = 667ms

UE synchronizes on the strongest correlation peak27Frame Synchronization..2560 chipsacpSlot # ?P-SCHacpSlot #?1611S-SCHacpSlot #?2Group 4Slot 12,13,14

256 chipsS-SCH

P-SCH512 Primary Scrambling Codes divided into 64 groups28Slot Synchronization

P-SCH1P-SCH3P-SCH2P-SCH1S-SCH1P-CCPCHP-CCPCHP-SCH2S-SCH2P-CCPCHP-CCPCHP-SCH3S-SCH3P-CCPCHP-CCPCHP-CCPCH1 Slot = 667ms

UE synchronizes on the strongest correlation peak29Cell Information

P-SCH: Coverage indication, Slot SynchronizationS-SCH: Frame Synchronization, Group identificationP-CPICH: Scrambling Code IdentificationP-CCPCH: System Information BroadcastLogical ChannelBCCHTransport ChannelBCHPhysical ChannelP-CCPCHOVSF Cch,256,1Primary Scrambling CodeTransmitted during 9/10th slotBit Rate: 12.3 kbpsRLC Mode: transparentMac-B: transparent30Intra-Frequency Cell Reselection sample

31Cell selection and reselection Cell Selection criteria The cell selection criterion S is fulfilled when: where

32Cell Selection ParametersParameterObjectRangeDefault ValueRecommended ValueClassqQualMinCellSelectionInfoInt [-24..0](dB)-10-16C2qRxLevMinCellSelectionInfoInt [-115..-25]Step = 2 (dBm)-45-115C2maxAllowedUlTxPowerUlUsPowerConfInt [-50..33](dBm)3333C3P_Max = maximum UE output power (dBm) according to its classPower ClassMaximum Output Power (dBm)13322732442133Cell Reselection Procedure

SqualSintraSearchSinterSearchSinterRATMeasurement on same frequencyMeasurement on other frequenciesMeasurement on other RATIf Squal = CPICH_Ec/No qQualMin < ThresholdAssociated measurements are performedThresholds are broadcasted in SIB 11In UMTS02, 2 types of measurements are done: Intra frequency and inter RAT Threseholds given as example34Cell Reselection ParametersParameterObjectRangeDefault ValueRecommended ValueClassqHyst1CellSelectionInfoInt [0..40] (dBm)Step = 2104C2qHyst2CellSelectionInfo

Int [0..40] (dB)Step = 246C2qOffset1snGSMCell

Int [-50..50] (dB)0TBDC0qOffset2snUMTSFDDNeighbouringInt [-50..50] (dB)0TBDC0qualMeasCPICH_EcNo or CPICH_RSCPCPICH_EcNoN.A.StatictReselectionCellSelectionInfoInt [0..31] (s)316C235MeasurementsThe different types of air interface measurements are:

Intra-frequency measurements: measurements on downlink physical channels at the same frequency as the active set. A measurement object corresponds to one cell.

Inter-frequency measurements: measurements on downlink physical channels at frequencies that differ from the frequency of the active set. A measurement object corresponds to one cell.

Inter-RAT measurements: measurements on downlink physical channels belonging to another radio access technology than UTRAN, e.g. GSM. A measurement object corresponds to one cell.

36Handover (Handoff)There are following categories of handover (also referred to as handoff):

Hard handover means that all the old radio links in the UE are removed before the new radio links are established. Hard handover can be seamless or non-seamless. Seamless hard handover means that the handover is not perceptible to the user. In practice a handover that requires a change of the carrier frequency (inter-frequency handover) is always performed as hard handover.

Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN. Soft handover is performed by means of macro diversity, which refers to the condition that several radio links are active at the same time.

Softer handover is a special case of soft handover where the radio links that are added and removed belong to the same Node B (i.e. the site of co-located base stations from which several sector-cells are served. 37Handover (Handoff)The most obvious cause for performing a handover is that due to its movement a user can be served in another cell more efficiently (like less power emission, less interference). It may however also be performed for other reasons such as system load control.

Active Set is defined as the set of Node-Bs the UE is simultaneously connected to (i.e., the UTRA cells currently assigning a downlink DPCH to the UE constitute the active set).The maximum active set size at the RNC is determined by the parameter MaxAciveSetSize3 to 4 cells, the larger the active set size the more likely it is that Iub linkefficiencyis reduced (more than one resource for asingle connectiondue to SHO)

Cells, which are not included in the active set, but are included in the CELL_INFO_LIST belong to the Monitored Set.

Cells detected by the UE, which are neither in the CELL_INFO_LIST nor in the active set belong to the Detected Set. Reporting of measurements of the detected set is only applicable to intra-frequency measurements made by UEs in CELL_DCH state.

38PRIMARY CELL ELECTION ALGORITHM (MONITORED SET UPDATE)The primary cell election algorithm applies to soft HO. It is used for monitored set determination and a pointer to mobility parameter.

The Monitored Set should be updated each time the primary cell of active set changes. A measurement control message is sent (with measurement commend set to modify) is sent to the UE in order to update the monitored set. The message contains the cell to add/remove from the monitored and should follow the ACIVE SET UPDATE message.

The primary cell algorithm is called from SHO algorithm; therefore it is performed each time a MEASUREMENT REPORT is received by the SRNC.

Measurement control used for monitored set updateCompressed modeCompressed mode is when the mobile goes into a slotted transmitmode whereby it opens up an idle period (transmission gap) where it can monitor another carrier or technology (GSM). The impact isthat tomaintain the same bit rate, it halves the SF, and therefore increases power level causing higher interference to the network. If the SF cannot be halved then the bit rate of the bearer decreases. If they seem knowledgably, ask them ifthey knowwhat messages and events trigger andconfigurecompressed mode on/off. 2D event for on, 2F for off. Messages would for configuration would be RADIO BEARER RECONFIGURATION, TRANSPORT CHANNEL RECONFIGFURATION or PHYSICAL CHANNEL RECONFIGURATION.40Compressed Mode During inter-frequency handover the UEs must be given time to make the necessary measurements on the different WCDMA carrier frequency. 1 to 7 slots per frame can be allocated for the UE to perform this intra frequency (hard handover).

Why is compressed mode needed?In UTRAN FDD, transmission/reception by the mobile is continuous : no idle periods are available for monitoring other frequencies if the UE has only a single receiverHow is it done?Transmission gaps are created in the radio frame in DL and/or UL to allow the UE to switch to another frequency, perform measurements on another carrier (FDD, TDD or GSM) and switch backTransmission gaps are positioned in one radio frame or at the boundary of 2 radio frames in regular intervals referred to as a transmission gap pattern sequenceno more than 7 slots are used in any one radio frame to create the transmission gap.How is it done?Two approaches can be taken in creating the transmission gaps of the transmission gap pattern sequenceModifiy the physical layer parameters (by puncturing or spreading factor reduction) to allow all information bits to be transmitted.Restrict the bit rate (by higher layer scheduling) to match the fewer available transmission slots in a compressed radio frame.In both approaches, the goal is to not loose transmission framesWho controls it?Compressed mode is under the control of the UTRANCompressed mode is configured by the RNC per UE in the form of transmission gap pattern sequences given to the UE via RRC signallinggiven to the node B via NBAP signallinga transmission gap pattern sequence is associated with a specific measurement purpose: FDD measurements, TDD measurements, GSM initial BSIC identification, GSM BSIC reconfirmation, GSM RSSI measurement

41Physical layer Aspects Compressed Mode Methods Three methods are available to create transmission gapsPuncturing: additional puncturing/fewer repetitions are performed compared to normal mode to be used only in DLto be used only in the case of mapping to fixed positionsscrambling and channelisation code remain unchangedSpreading Factor Reduction: SF is divided by 2can be used in UL and DLcan be used with mapping to flexible positionsto be used only when SF>4only 2nd DTX insertion and physical channel mapping is modifiedmay lead to channelisation code shortage and the need to use a secondary scrambling code42Cell Shakedown PurposeTo test Call Setup (Voice and FTP) in each cellTo test Handoffs (Soft and Softer) between CellsVerify antenna orientationPrimary Pilot Ec/IoScrambling Code for each cellUE transmit powerPath Balance MethodBy driving clockwise and anticlockwise within a designated route around the the base station (about 30% of the site coverage area).

43Difference between Scanner data & UE Data CollectionScannerPrimary Common Pilot Channel (P-CPICH) scrambling code measurementsContinuous Wave (CW) measurementsSpectrum analysisSynchronization Channel (SCH) code word measurements

UEData/Voice/Video CallsLayer 3 messages loggingLayer 2 messages logging (Transport channel)RRC State loggingUE Transmit PowerSIRServing Cell / Active Set / Monitored SetEvents GSM neighbor measurements

Difference in data collectionAntenna CableSamplingSolution: Perform a calibration drive.An overview of cluster performance based on scanner Best Serving CPICH RSCP and Ec/Io measured data.

43Inner loop & ScannerIn pre-launch optimization, how are missing neighbors usually detected?Usually you use a scanner and compare the best pilots in Ec/Io from the scanner against that of the active set and monitoredset froman active UE. If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE, there is a possible missingneighbor. One would thenverifythat theneighborappears in definedneighborlist from the OSS.

Explain Inner and Outer loop power control and who controls them.If they start talking about Open andClosed LoopPC, tell them you want Inner/OuterClosed LoopPC. Inner loop power control is performed by the NodeB to set thetransmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec). Outer loop power control is performed by the RNC to set the target SIR based on the required BER/BLER for the requested services (occurs up to 100 times per sec).

45Drop after active set updateSymptom:Normally, the observed sequent messages in the UE side are:UTRAN -> UE: Active set update (to request the UE to remove a cell, e.g. SC281)UE -> UTRAN: Active set update completeUTRAN -> UE: Measurement Control (update neighbour list)UE -> UTRAN: Measurement report (to propose to add7)UTRAN -> UE: Active set update (to request the UE to add SC 137)DROP.......(since no Active set update completion was sen after 12 secs )The radio performances no matter DL and UL are very good.Possible solution: No solution, check this problem with UE vendor.

In SoftHandover the UE is connected to more than one Radio Base Station(RBS) simultaneously. At least one radio link is always active andthere is no interruption in the dataflow during the actual handover.The signals are received in the UE and combined in the RAKEreceiver to give protection against fading.46Soft/Softer Handover Radio Link Addition and Radio Link Removal.

Reference:User Description and Engineering Guidelines 75/1551-HSD 101 02/1 UenB2 Ericsson AB 2003 - All Rights Reserved 47Drop after active set update, Cont.

BLER is getting worseRF conditionis o.k.48Drop after active set update, Cont.

No Active Set Completion was sent after Active Set Update.FINAL WORDSFor network tuning, we need to relay on field measurements which require extensive drive testsFinding the best possible configuration for antenna heights, tilts, azimuths and parameter setting for all the present cells/sectors in the network and also for any new sites that might be needed to improve coveragePower adjustment can also be used for network tuning but can become complicated and result in poor network performanceUse of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antennaNeighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction). Keep neighbour list upto 20. Automated tools are needed that could suggest the best possible neighbour relations, antenna heights and tilts by using both the field measurements and the propagation models & simulations Skilled people, right methods and advanced tools are needed to perform 3G tuning and optimisationIf a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur?UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH). If they talk about inactivitytimersand mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH, that is also possible. Bonus theysay theywould see RADIO BEARER RECONFIGURATION messages when the states are changing.Name the 4 RRC Connected Modes (states) and describe the characteristics of each.Cell-DCH: UE has been allocated a dedicated physical channel inuplink and downlink.Cell-FACH: UE listens to RACH channel (DL) and is allocated a FACH channel (UL). Small amounts of UL/DL data can be transfers in this state. The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message.Cell-PCH: UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel. The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message. No data can be transferred in the UL in this state.URA-PCH: UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel. The RNC tracks the UE down to the URA level.

Power controlIn the uplink the base station measures the received Signal-to-Interference Ratio (SIR) and compares this to a target SIR. If themeasured SIR is below the target then the base station requests themobile to increase its power (and vice versa). This type of powercontrol is known as the Inner-loop power control and is capable ofadjusting the transmit power in steps of, for example 1 dB at a rateof 1500 times per second. Inner-loop power control is onlyapplicable for connections on dedicated channels

PHY

MAC

U-plane information

C-plane signalling

Logical Channels

Transport Channels

RLC

RLC

RLC

L2/BMC

RLC

RLC

L3

RLC

L2/MAC

L1

GC

Nt

DC

L2/RLC

RLC

RLC

control

Duplication avoidance

control

control

RRC

UuS boundary

control

BMC

L2/PDCP

PDCP

PDCP

GC

control

Nt

DC

ODMA Dedicated Traffic Channel (ODTCH)

ODMA Common Control Channel (OCCCH)

ODMA Dedicated Control Channel (ODCCH)

Dedicated Traffic Channel (DTCH)

Traffic Channel (TCH)

Control Channel (CCH)

Common Control Channel (CCCH)

EMBED Word.Picture.6 Dedicated Control Channel (DCCH)

Paging Control Channel (PCCH)

Broadcast Control Channel (BCCH)

Synchronisation Control Channel (SCCH)

Common Traffic Channel (CTCH)

Shared Channel Control Channel (SHCCH)

_968747715.doc

Dedicated Control Channel (DCCH)

Scrambling

Code Groupslot number

#0#1#2#3#4#5#6#7#8#9#10#11#12#13#14

Group 0112891015810162715716

Group 111516731416310512141210

Group 212115551216611216111512

Group 3123186525844637

Group 412166611155121151216112

Group 619101310111515916121413161411

Group 629111215129131311141016151416

Group 639121015131491415111113121610

Squal = Qqualmeas Qqualmin

Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation

Pcompensation max(UE_TXPWR_MAX_RACH P_MAX, 0)

for FDD cells:Srxlev > 0 AND Squal > 0

for TDD cells:Srxlev > 0

for GSM cells:Srxlev > 0