wcdma key technology

WCDMA Key TechnologiesZTE University

ObjectivesAt the end of this course, you will be able to:Master key technologies of WCDMAMaster characteristic of WCDMA system capacity

ContentWCDMA Key TechnologiesPower ControlHandover ControlAdmission ControlLoad ControlCode Resource AllocationRAKE ReceiverWCDMA Capacity Features

Power ControlCDMA is not a new technologyPower control is a key technology of CDMA systemPower control is the key path for launching the large scale CDMA commercial networkCDMA is a typical self-interference system, thus the chief principle is that any potential surplus transmitted power for service must be controlled.

Why Power Control?All CDMA users occupy the same frequency spectrum at the same time! Frequency and time are not used as discriminators.CDMA operates by using codes to discriminate between users.CDMA interference comes mainly from nearby usersEach user is a small voice in a roaring crowd -- but with a uniquely recoverable code.To achieve acceptable service quality, the transmit power of all users must be tightly controlled so that their signals reach the base station with the same signal strength and the absolute minimum power level demanded to avoid the Near-Far Effect.

Near-Far Effect

Each terminal is an interference source to the others. The Near-far effect will impact the capacity tremendously PowerfPower control will reduce the cross interference significantly and improve the total capacityPowerfPower control

Overcome near-far effect and compensate signal fading Reduce multi-access interference and guarantee cell capacity Extend battery lifeDownlink Power ControlUE transmitted signalPower control command (TPC)Uplink Power ControlCell transmitted powerPower control command (TPC)Purpose of Power Control

Category of Power controlUERNCNode BOpen loop power controlno feedbackClose loop power controlfeedbackUENode BRNCOuter-loopInner-loop

Open LoopMeasure the channel interference condition and adjust the initial transmitted powerClose LoopInner LoopMeasure the SIR (Signaling to Interference Ratio), compare with the target SIR value, and then send power control instruction to UE.The frequency of WCDMA inner loop power control is 1500Hz.If measured SIR>target SIR, decrease the UE transmitted power.If measured SIR target BLER, decrease the target SIR value.If measured BLER

Open Loop Power ControlGeneral principals of open loop power controlOpen loop power control is applied to estimate the initial transmitted power for a new radio link.P-CPICH signal is used in Downlink Open Loop Power Control, which is measured by UE to estimate the initial transmitted power.The following factors will also be considered, such as service QoS and data rate, Eb/No requirements of establishing service, current downlink total Transmitted Power and interference from neighbor cell etc.

Try to get the equal receiving Eb (Energy per bit) of each UE at Node BNodeBUETPC instructionMeasure receiving SIR and compare to target SIRInner loopSet SIRtar1500HzEach radio link has its own control circleClose Loop Inner Loop Power Control

Close Loop Inner Loop Power ControlGeneral principals of inner loop power controlThe receiver compares the SIR value of received signal with target SIR, and then sends back TPC instruction. According to the instruction, the sender will decide to increase/decrease the transmitted power.The adjusted rang=TPC_cmdTPC_STEP_SIZEInner loop power control is required for the following channelsDPCH, PDSCH, PCPCHInner loop power control is not required for the following channels P-CPICH(S-CPICH), P-CCPCH(S-CCPCH), PRACH etc.

NodeBUETPC instructionInner loopSet SIRtarGet data flow with stable BLERMeasure BLER of TRCHOuter LoopRNCMeasure receiving BLER and compare to target BLERSet BLERtar10-100HzMeasure receiving SIR and compare to target SIRClose Loop Inner Loop Power Control

Close Loop Outer Loop Power ControlOuter Loop Power Control algorithmEmploy the inner loop power control to keep SIR close to target SIR.Measure the quality of service, including target BLER, CRC indicator and SIR Error, then set the value of SIR_Target.Tune the target SIR with pre-defined step as the adjustment parameter for inner loop power control to keep the service in good quality in time-varying wireless propagation environment.The uplink open loop power control algorithm is executed in the RNC while the downlink one is executed in UE.

The Effect of Power ControlThe purpose of DL power control:Saving power resource of NodeB. Reducing interference to other NodeB.The purpose of UL power control:Overcoming Near-Far effect. Extending UE battery life.WCDMA system capacity depends on the effect of power control

Whats When UE is moving from the coverage area of one site to another, or the quality of service is declined by external interference during a service, the service must be handed over to an idle channel for sustaining the service. Handover is used to guarantee the continuity of service Handover is a key technology for mobile networking

Category of Handover Intra-RNC, inter-Node B Inter-RNCSoft handover (SHO) Same Node B, Inter-sectorSofter handover Intra-frequency Inter-frequency Inter-system (3G&2G) Inter-mode (FDD&TDD)Hard handover (HHO)WCDMA system support multiple handover technology

Handover DemonstrationHard Handover

Soft Handover/Softer HandoverSoft HandoverSoft-Softer HandoverSofter Handover

Hard HandoverDuring the hard handover procedure, all the old radio links with the UE are abandoned before new ones are established, so there must be service interruption during the HHO.Hard handover may occur in the following main cases When the UE is handed over to another UTRAN carrier, or another technology mode.When soft handover is not permitted (if O&M constraint)Hard HandoverNode BSRNCRNC or BSCCNNode B or BTS

Soft/Softer HandoverThe soft/softer handover allows to migrate from one cell to another without service interruption or without deleting all old radio links.UE can connecte to more than one cell simultaneously and take benefit from the macro-diversity. Soft HandoverSofter HandoverCNCNIurThe two Node Bs may belong to the same RNCThe two Node Bs may belong to the Same RNCSoft HandoverSofter HandoverSRNCDRNCCNNode BSRNCCNSoft HandoverSofter HandoverNode BCN

WCDMA General Handover Procedures---- Handover TrilogyMeasurement ControlUTRAN demands the UE to start measurement through issuing a measurement control message.Handover decisionUTRAN makes the decision based on the measurement reports from UE. The implementation of handover decision is various for different vendors. It impacts on the system performance critically.Handover executionUTRAN and UE execute different handover procedure according to the handover command .

General Procedure of Handover Control (I)MeasuringThe measurement objects are decided by RNC. Usually, either Ec/N0 or RSCP (Received Signal Code Power) of P-CPICH channel is used for handover decision.ZTE RNC adopts Ec/N0 measurement, because Ec/N0 embodies both the received signal strength and the interference. The relation of Ec/N0 and RSCP is shown as follows: Ec/N0 RSCP/RSSIIn the above equationRSSIReceived Signal Strength Indicatoris measured within the bandwidth of associated channels

General Procedure of Handover Control (II) ReportingPeriod report triggered handoverBase on the filtered measurement resultEvent report triggered handoverBase on the eventSoft HandoverHard HandoverPeriodEventMeasurement result filtered in UEEvent decided in RNCHandover decided in RNCMeasurement result filtered in UE Event decided in UEHandover decided in RNC

General Procedure of Handover Control (III) Handover algorithmAll the handover algorithms including soft handover, hard handover and so on are implemented on the event decision made according to the measurement reports. Events defined in 3GPP specificationsIntra-frequency events1A~1FInter-frequency events2A~2FInter-RAT events3A~3DNote: RAT is short for Radio Access Technology, e.g. WCDMA&GSM

Concepts Related to Handover Active Set: A set of cells that have established radio links with a certain mobile station.User information is sent from all these cells.Monitored Set: A set of cells that are not in the active set but are monitored according to the list of adjacent cells assigned by the UTRAN. Detected Set: A set of cells that are neither in the active set nor in the monitor set.

Soft handover process MeasurementRNC sends a measurement control message to UE. UE should perform measurement as required and report the measurement result.Generally, the measured parameter is the common pilots Ec/No.DecisionRNC stores data of different cells according to the measurement results.RNC makes preliminary decision according to the event decision method. e.g. When the event is reported and the target cell is acceptable, send an active set update command to add/delete the cell into/from the active set.ExecutionThe RNC sends an active set update command to UE and UE starts handover.

Soft handover eventsEventDescription1AQuality of target cell improves, entering a report range of relatively activating set quality1BQuality of target cell decreases, depart from a report range of relatively activating set quality1CThe quality of a non-activated set cell is better than that of a certain activated set cell1DBest cell generates change1EQuality of target cell improves, better than an absolute threshold1FQuality of target cell decreases, worse than an absolute threshold

An Example of SHO ProcedurePilot Ec/Io of cell 1timePilotEc/IoConnect to cell1 Event 1A Event 1C Event 1B add cell2replace cell1 with cell 3remove cell3Pilot Ec/Io of cell 2Pilot Ec/Io of cell 3ttt

Example of soft handover

RNS RelocationRNS relocation can :Reduce the Iur traffic significantlyEnhance the system adaptabilityCore NetworkCore NetworkServing RNSTarget RNSServiing RNSTarget RNSIuIuIurRNSRadio Network Sub-system

Hard HandoverHard handover measurement is much more complex for UE than soft handover measurement.Inter-frequency hard handover requires UE to measure the signal of other frequencies.WCDMA employs compressed mode technology to support inter-frequency measurement.

Admission ControlThe admission control is employed to admit the access of incoming call. Its general principal is based on the availability and utilization of the system resources.If the system has enough resources such as load margin, code, and channel element etc. the admission control will accept the call and allocate resources to it.The admission control is employed to admit the access of incoming call. Its general principal is based on the availability and utilization of the system resources.If the system has enough resources such as load margin, code, and channel element etc. the admission control will accept the call and allocate resources to it.

Purpose of Admission ControlWhen user initiates a call , the admission control should implement admission or rejection for this service according to the resource situation.The admission control will sustain the system stability firstly and try the best to satisfy the new calling services QoS request, such as service rate, quality (SIR or BER), and delay etc. basing on the radio measurement. Admission control is the only access entry for the incoming services, its strategy will directly effect the cell capacity and stability, e.g. call loss rate, call drop rate.

Admission Control in UplinkItotal_old+I >Ithreshold The current RTWP (Received Total Wide Power) value of cell, which is reported by Node B AccessThresholdInterference capacityService priorityReserved capacity for handoverIown-cellIother-cellThe forecasted interference including the delta interference brought by the incoming service is calculated by the admission algorithm, and its result depends on the QoS and transmission propagation environment

Admission Control in DownlinkPtotal_old+P>=Pthreshold Access ThresholdThe forecasted TCP value including delta power required for the incoming service is calculated by the admission algorithm, and its result depends on the QoS and transmission propagation environment.The current TCP value of cell, which is reported by Node BTransmitted Carrier Power*PmaxMax TCP of cellService priorityReserved capacity for handover

Load controlThe purpose of load control is to keep the system load under a pre-planned threshold through several means of decreasing it, so as to improve the system stability.The speed and position changing of UE may worsen the wireless environment.Increased transmitted power will increase the system load.Purpose of Load Control

Load Control FlowsStartDecisionLight loadedOver loadedNormal loaded1.Handover in andaccess are forbidden2. TCP increase isforbidden3. RAB service ratedegrade4. Handover out5. Release call (call drop)1. Handover in and access are allowed2. Transmitted code power (TCP) increase is allowed3. RAB service rate upgrade is allowed1. Handover in and access are allowed2. TCP increase is allowed

Load Control in Uplink TriggersRTWP (Received Total Wide-band Power) value from measurement report exceeds the uplink overload threshold;Admission control is triggered when rejecting the access of services with lower priority due to insufficient load capacity in uplink.Methods for decreasing loadDecrease the target Eb/No of service in uplink;Decrease the rate of none real time data service;Handover to GSM system;Decrease the rate of real time service, e.g. voice call;Release calls.Methods for increasing loadIncrease the service rate.

Load Control in Downlink TriggersTCP (Transmitted Carrier Power) value from measurement report exceeds the downlink overload threshold;Admission control is triggered when rejecting the access of services with lower priority due to insufficient load capacity in downlink. Methods for decreasing loadDecrease the downlink target Eb/No of service in downlink;Decrease the rate of none real time data service;Handover to coverage-shared light loaded carrier;Handover to GSM system;Decrease the rate of real time service, e.g. voice call;Release calls. Methods for increasing loadIncrease the service rate.

Cell breathing is one of the means for load controlThe purpose of cell breathing is to share the load of hot-spot cell with the light loaded neighbor cells, therefore to improve the utilization of system capacity.Cell Breathing Effect

Example for load controlCell Breathing EffectWith the increase of activated terminals and the increase of high speed services, interference will increase.The cell coverage area will shrink.Coverage blind spot occursDrop of call will happen at the edge of cellCoverage and capacity are interrelated

WCDMA Code ResourceWCDMA code resource includingChannelized Code (OVSF code) Uplink Channelized CodeDownlink Channelized CodeScrambling Code (PN code)Uplink Scrambling CodeDownlink Scrambling Code

Function of OVSF CodeOC1, OC2OC3, OC4OC5, OC6, OC7OC1 , OC2, OC3OC1, OC2OC1, OC2, OC3, OC4Uplink: distinguish different radio channels from the same UE.Downlink: distinguish different radio channels from the same NodeB.

Function of PN codeDownlink: distinguish different CellsUplink: distinguish different UEs

PN3PN4PN5PN6PN1PN1Cell Site 1 transmits using PN code 1PN2PN2Cell Site 2 transmits using PN code 2

Why Code Resource Planning?The OVSF (Orthogonal Variable Spreading Factor) code tree is a scarce resource and only one code tree can be used in each cell. In order to make full use of the capacity, and support as many connections as possible, it is important to plan and control the usage of channel code resource.Downlink PN code allocation should be planned to avoid the interference between neighboring cells.The uplink PN codes are sufficient, but RNC should plan the codes to use for avoiding allocating same code to different users in inter-RNC handover scenario.

Code Resource PlanningThe uplink and downlink scrambling code can be planned easily by computer.The uplink channelized code does not need planning, for every UE can use the whole code tree alone.Therefore, only the downlink channelized code is planned with certain algorithm in RNC.Each cell has one primary scrambling code, which correlates with a channel code tree. All the users under this cell share this single code tree, so the OVSF code resource is very limited.The downlink channelized code tree is a typical binary tree with each layer corresponds to a certain SF ranging from SF4 to SF512.

Generation of Channelized Code

SF = 1

SF = 2

SF = 4

Cch,1,0 = (1)

Cch,2,0 = (1,1)

Cch,2,1 = (1,-1)

Cch,4,0 =(1,1,1,1)

Cch,4,1 = (1,1,-1,-1)

Cch,4,2 = (1,-1,1,-1)

Cch,4,3 = (1,-1,-1,1)

OVSF Code Tree

Channelized Code CharactersCode allocation restriction The code to be allocated must fulfill the condition that its ancestor nodes including from father node to root node and offspring nodes in the sub tree are not allocated; Code allocation side effectThe allocated node will block its ancestor nodes and offspring nodes, thus the blocked nodes will not be available for allocation until being unblocked .

Strategy of Channelized Code AllocationFull utilizationThe fewer the blocked codes, the higher code tree utilization rate. Low ComplexityShort code first. Allocate codes for common channels and physical shared channels prior to dedicated channels.Guarantee the code allocation for common physical channels. Apply certain optimized strategy to allocate codes for downlink dedicated physical channels.

An Example of Code Allocation 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31SF = 4SF = 8SF = 16SF = 32SF = 4SF = 8SF = 16SF = 32Red spots represent the codes that have been allocatedGreen spots represent the codes that are blocked by the allocated offspring codesBlue spots represent the codes that are blocked by the allocated ancestor codes;Black spots represent the codes that to be allocated;Choose one code from three candidates

Planning of downlink PN codePN1PN2PN3PN7PN6PN4PN5PN7PN6PN4PN5PN1PN2PN3PN1PN2PN3PN7PN6PN4PN5PN1PN2PN3PN7PN6PN4PN5PN1PN2PN3PN7PN6PN4PN5PN1PN2PN3PN7PN6PN4PN5

RAKE Receiver can effectively overcome the multi-path interference, consequently improve the receiving performance.RAKE ReceiverThe multi-path signals contain some useful energy , therefore the CDMA receiver can combine these energy of multi-path signals to improve the received signal to noise ratio. RAKE receiver adopts several correlation detectors to receive the multi-path signals, and then combines the received signal energy.

RAKE Receivingd1d2tttd3transmittingReceivingRake combinationnoise

Multi-finger receiverTraditional receiverMulti-path signals are treated as interference.The receiving performance will decline because of the Multi-address Interference (MAI).Precondition of Multi-finger receiver Multi-finger receiver utilizes the Multi-path Effect.Multi-finger signals can be combined through relative processMulti-finger time delay is larger than 1 chip interval, which is 0.26us=>78m.

Multi-finger receiverreceivertransmittercodingdecodingDirect signalReflected signalDispersive time < 1 chip intervalMulti-finger receiver cant supply multi-finger diversitydecodingDirect signalReflected signaltransmitterreceiverDispersive time > 1 chip intervalMulti-finger receiver can supply multi-finger diversity, signal gain is improvedcoding

RAKE ReceivingreceiverSingle receivingSingle receivingSingle receivingsearchercalculatecombiningtts(t)s(t)signalRAKE Receiving overcomes multi-finger interference, improves receiving performance

Combination of Multi-fingersMaximal ratio combining (MRC)at each time delay phase shifting by adding Finger 1

Finger 2

Finger 3

Capacity of WCDMAUL capacity is restrained by interferenceDL capacity is restrained by the power of NodeB

Power RisingPower rising occurs because of the Multiple Access Interference (MAI) resulting from the non-orthogonal code channels.

WCDMA network Meeting RoomCode channel transmit talk with dialectsChannel power voice tonePromised channel quality listen clearlyChannel power rise voice tone risePower climb voice climbCollapse over the range can not hear each other

Power Rising

Quantity of Subscriber

Quantity of Subscriber-- The Total Bandwidth Received by Node B

The Total Bandwidth Power Received by Node B (dBm)

Capacity of WCDMA SystemUnder the circumstance of single services:

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Capacity of WCDMA System...Under the circumstance of mixed servicesXYZ++

WCDMA Capacity FeaturesWCDMA capacity featureWCDMA capacity is Soft Capacity.The Concept of Soft CapacityThe system capacity and communication quality are interconvertible.Different services have different capacity.Different proportion of services have different capacity for mixed services.The capacity is also restricted to the allocation of code resource.

Different combination of service has different capacityDifferent service has different capacityConcept of Soft CapacitySystem capacity and QoS can be interconverted

QualityCoverageCapacityAll the key technologies adopted are used to try to achieve the optimal balance of the three factorsCrucial Factors for WCDMA Network (CQC)

Coverage and CapacityWCDMA performance is determined by such factors asNumber of usersTransmission rateMoving speedWireless environmentindoorsOutdoorsThe radius of cell depends on such factors as: Local radio conditions (local interference) Traffic in neighbouring cells (remote interference)Cell Radius decrease according to the Increase of user number

Coverage/capacity VS Data RateHigher data rate needs higher powerHigh data rate transmission is only available nearby the station>12.2 kbps>64 kbps>384 kbps>144 kbpsCoverage decreaseSubscriber num increase

DL/UL: Add carrier six sectorsUL Tower Mounted Amplifier (TMA) 4 Rx Div OTSRDL transmission diversity (Tx Div) high power amplifierAdd basestation last choiceOptimization methodsTo overcome Cell Breathing Effect caused by increased traffic and meet different requirements for capacity and coverage in different environment, following solutions can be applied:

Factors affects WCDMA Capacity

FactorsImpact on WCDMA capacityPower ControlReducing interference, saving power and Increasing capacityHandover ControlImpacting the capacity through applying different proportion and algorithm of soft handover Admission ControlAdmitting a connection base on the load and the admission threshold of planned capacity Load ControlMonitoring system load and adjusting the ongoing services to avoid overloadOVSF Code The Allocation of codes impacts the maximum number of simultaneous connections.RAKE ReceiverThe advanced receiving and baseband processing technology is introduced to overcome the fast fadingWireless EnvironmentWireless environment such as interferences, UE position and mobility etc. can influent the cell capacity

Exercise what is the near-far effectwhat is the purpose of Power Control .Power control is classify into ( ) ( ) and ( )pls describe WCDMA Handover technology category.Handover procedure includes ( ) ( ) and ( )What is the Cell Breathing Effect.Whats the relation between Capacity, Quality and Coverage?

Good morning! Today we will study the WCDMA Key Technnologies ! The Target of the part ,we should master this two points: First, we should master the key technologies of WCDMASecond, we should master the characteristic of WCDMA system capacityOK! Lets talk about the key technologies of WCDMA!There are six parts of the Key Technologies: Power Control, Handover Control, Admission control, Load control, Code Resource Allocation, RAKE ReceiverWe will study these key technologies one by one,We first talk about the power control, in WCDMA system , the power control is the most important part *CDMAPower control is an import part in the WCDMA system. Provided that all UEs in a cell transmit signals with the same power. The signals reaching Node B from UEs close to Node B are stronger; while those reaching Node B from UEs far from Node B are weaker. This may lead to overpower of weak signals by stronger signals. That is the so-called near-far effect. WCDMA is a self-interference system and all UEs use the same frequency. Therefore, the near-far effect is more serious. In addition, for the WCDMA system, the downlink of Node B is power restricted. To achieve qualified call quality when the TX power is small, it is required that both Node B and UE can adjust the power needed by the transmitter in real time according to the communication distance and link quality. This process is the so-called power control. WCDMA10dBCDMA

UEP-CPICHQoSEb/N0HTpcTPCTPCTPC_cmdTPC_STEP_SIZEDPCH, PDSCH, PCPCHP-CPICH(S-CPICH), P-CCPCH(S-CCPCH), PRACHHNASQoS BLERSIRSIRBLER

SIRQoSSIRTargetSIRSIRTarget CRCISIRTargetBLERCRCSIRerrorSIRFER(BLER)FER(CRCI).

TTIRNCSIRtargetSIRtargetSo - Open loop happens before accessing the network and closed loop is during the call. More ppt if you have time ,reference. There are six parts of the Key Technologies: Power Control, Handover Control, Admission control, Load control, Code Resource Allocation, RAKE ReceiverWe will study these key technologies one by one,Intra-freq Diversity mode is different, must be hard handoverMSCmsc

GoS=Pb+10Pd PdPb

Hard handover indicates that contacts are set up between a UE and a new cell after the UEs radio link with the previous cell is broken. There is only one radio link at any moment during hard handover.Soft/Softer HO applies to dedicated physical channels and not to shared or common transport channelson the same carrier frequencySoft handover indicates a handover between two cells with the same carrier frequency. In this case, a UE will not stop the contact with the previous cell when set up contacts with a new cell. In the soft handover status, radio links can be set up between a UE and more than one cell.

RSSI(Received Signal Strength Indicator) the wide-band received power within the relevant channel bandwidth. Measurement shall be performed on a UTRAN downlink carrier. The reference point for the RSSI shall be the antenna connector of the UE.

RSCP(Received Signal Code Power) the received power on one code measured on the Primary CPICH. The reference point for the RSCP shall be the antenna connector of the UE. If Tx diversity is applied on the Primary CPICH the received code power from each antenna shall be separately measured and summed together in [W] to a total received code power on the Primary CPICH.

Ec/N0 : The received energy per chip divided by the power density in the band. The Ec/No is identical to RSCP/RSSI. Measurement shall be performed on the Primary CPICH. The reference point for the CPICH Ec/No shall be the antenna connector of the UE. If Tx diversity is applied on the Primary CPICH the received energy per chip (Ec) from each antenna shall be separately measured and summed together in [Ws] to a total received chip energy per chip on the Primary CPICH, before calculating the Ec/No.

1X 1ACPICH 1BCPICH 1CCPICHCPICH 1D 1ECPICH 1FCPICH 2X 2a 2b 2c 2d 2e 2f 3X 3aUTRAN 3b 3c 3d

The RNC sends a measurement control message to UE, which contains the measurement result report mode, measurement object, measurement physical quantity, report physical quantity and some control parameters. Control order1A~1F2A~2F3A~3D1A1B1CActive SetActive Set1D1E1F There are six parts of the Key Technologies: Power Control, Handover Control, Admission control, Load control, Code Resource Allocation, RAKE ReceiverWe will study these key technologies one by one,RTTWCDMABPSKQPSK1bite/Hz2bites/Hz5MHz3.84MHz10Mbps3G2G 35%

There are six parts of the Key Technologies: Power Control, Handover Control, Admission control, Load control, Code Resource Allocation, RAKE ReceiverWe will study these key technologies one by one,>Noise rise>>

Load balance: inter-handover, intra-blind handoverThere are six parts of the Key Technologies: Power Control, Handover Control, Admission control, Load control, Code Resource Allocation, RAKE ReceiverWe will study these key technologies one by one,CDMAOVSF-OVSFCDMAC4,1C8,1C8,3C4,1

There are six parts of the Key Technologies: Power Control, Handover Control, Admission control, Load control, Code Resource Allocation, RAKE ReceiverWe will study these key technologies one by one,CDMARAKERAKERAKEMRAKE

Radio wave propagation on radio channels is characterized by much reflection, diffraction and fading of signal energy. These are due to space obstacles, such as buildings and hills, which result in multipath propagation, as shown in Fig. 1.22 Therere Two effects of multipath propagation :1.The code chip energies arrive at the receiver at distinguishable moments. The energies received constitute a multipath delay distribution, as shown in Fig. 1.22. When the chip rate is 3.84Mcps, the duration of a code chip is 0.26s. If the time difference of the multipath components is at least 0.26s, the WCDMA receiver can distinguish these multipath components and combine them into multipath diversity. 2.At a given delay location, there are usually many radio signal transmission paths with nearly the same distance. Therefore, even when the receiver moves a very short distance, there will be signal cancellation, also known as fast fading effect. WCDMA has the following solutions to counteract fading: 1.Use the Rake receiver to gather those delayed, distributed energies by multiple Rake finger peaks (related receiver). These finger peaks are allocated to these delay locations with significant incoming energies. 2.Use rapid power control to alleviate signal power fading. 3.Use convolutional coding, interleaving, and retransmission protocol to add redundancy and time diversity, to help the receiver restore subscriber data bits from fading.

Rake Correlative: disrelated : Dispersive:CDMARAKERAKECDMARAKERAKEDPCCH4IS-95 AW-CDMA3W-CDMAW-CDMA8RAKE75%RAKESearcher(correlation)FingerNodeBUERAKEDPCCH4 UENodeB8RAKE75%RAKEThis is typically done with a single matched filter (or any similar device) matched to the primary synchronization code The slot timing of the cell can be obtained by detecting peaks in the matched filter output.

There are six parts of the Key Technologies: Power Control, Handover Control, Admission control, Load control, Code Resource Allocation, RAKE ReceiverWe will study these key technologies one by one,WCDMA++

RAKE;

OTSROmni Transmission Sectorized ReceiveBSC OTSRTEUTransmission enhanced unit

wcdma key technology

Documents

power control instruction

ue transmitted power

absolute minimum power

cdma interference

new technologypower

target sir value

multiaccess interference

interference ratio