PowerPoint Presentation
WCDMA BASIC CONCEPT_1 Prepared By:A.K.M.AsaduzzamanRF Optimization Engineer(RNO)Radio Network Planning & Optimization DepartmentSTAR LINK.
Metro Telworks: An Introductionwww.metrotelworks.com# / 131Power
FrequencyTimeFrequencyTimePowerFrequencyTimePowerFDMATDMAW-CDMAAccess Technologies
Metro Telworks: An Introductionwww.metrotelworks.com# / 13The transmission medium is a resource that can be subdivided into individual channels according to different criteria that depend on the technology used.Heres how the three most popular radio technologies establish channels:FDMA (Frequency Division Multiple Access)Each user is on a different frequencyA channel is a frequency.TDMA (Time Division Multiple Access)Each user is on a different window in time (time slot)A channel is a specific time-slot on a specific frequency.W-CDMA (Wide-band Code Division Multiple Access)Each user uses the same frequency all the time, but it is mixed with different distinguishing code patterns.A channel is a unique (set of) code pattern(s).Duplex Spacing: 190 MHzFDDTimeFrequencyPower5 MHz5 MHzCode MultiplexULDLUMTS USER 1UMTS USER 2TimeFrequencyPowerTDD5 MHzCode Multiplex&Time Division 666.67 msDLULDLDLULUMTS USER 2UMTS USER 1W-CDMA: FDD or TDD
Metro Telworks: An Introductionwww.metrotelworks.com# / 13The possibility to operate in either FDD or TDD mode is allowed for efficient utilization of the available spectrum according to the frequency allocation in different regions. FDD and TDD are defined as follows: FDDA duplex method whereby the uplink and downlink transmissions use 2 separate frequency bands: Uplink: 1920 MHz - 1980 MHzDownlink: 2110 MHz - 2170 MHzEach carrier is 5 MHz wide and the uplink channel is 190 MHz away from the downlink. So there are up to 12 pairs of carriers.
TDDA duplex method whereby the uplink and downlink transmissions are carried over same frequency using synchronized time intervals. The carrier still uses a 5 MHz band. FDD mode is the preferred mode for macro-cellular applications.TDD mode is the preferred mode for the unpaired part of the spectrum. Because each time-slot can be assigned a different direction, the TDD mode offers a great flexibility to manage duplex and asymmetric traffic. The TDD spectrum will be used for low mobility coverage in urban areas.
TimeFrequencyWCDMACode
Users are using different orthogonal code sequenceWCDMA (Wide-Code Division Multiple Access)WCDMATraffic channels are assigned to users at same time, same frequency band, but with different code.
Metro Telworks: An Introductionwww.metrotelworks.com# / 134Freq. 1Freq. 1Code ACode BCode CNODE B1NODE B 2Code DCode EWCDMA ApplicationUsers are distinguished by scrambling codes and OVSF codesSelf-interference system WCDMA system is restricted to interference (GSM system is restricted to frequency resources)
Metro Telworks: An Introductionwww.metrotelworks.com# / 135
Single Frequency Network
Metro Telworks: An Introductionwww.metrotelworks.com# / 1363G Spectrum Allocation60 MHz30 MHz FDDTDD100 MHz15MHz 40 MHz 155MHz178518501755188019201980201020252110217022002400 Satellite Empty Satellite 2300
Metro Telworks: An Introductionwww.metrotelworks.com# / 1373G Spectrum Planning in ChinaMain Operating Frequency BandFDD mode1920-1980 MHz / 2110-2170 MHzTDD mode1880-1920MHz2010-2025 MHzSupplementary Operating Frequency BandFDD mode1755-1785 MHz / 1850-1880 MHzTDD mode2300-2400MHzFrequency Band for Satellite Mobile Communication System1980-2010 MHz / 2170-2200 MHzThe frequency bands, 825 - 835 MHz / 870 - 880 MHz, 885 - 915 MHz / 930 - 960 MHz and 1710 - 1755 MHz / 1805 - 1850 MHz, which are currently allocated to public mobile communication system are also allocated to expanded frequency bands of 3G public communication system, but frequency using mode remains the same for both uplink and downlink.
Metro Telworks: An Introductionwww.metrotelworks.com# / 138CNUTRANUEUMTS System StructureUTRANUMTS Terrestrial Radio Access NetworkCNCore NetworkUEUser Equipment
Metro Telworks: An Introductionwww.metrotelworks.com# / 13UMTS System Architecture
Metro Telworks: An Introductionwww.metrotelworks.com# / 13UMTS Network Architecture
Metro Telworks: An Introductionwww.metrotelworks.com# / 13Terminology of UMTS RNS NetworkUTRAN: UMTS Terrestrial Radio Access NetworkRNS: Radio Network SubsystemRNC: Radio Network ControllerUE: User EquipmentUu: Radio InterfaceIub: The interface between NodeB and RNCIur: The interface between RNCsIu_CS: between RNC and CS domainIu_PS:between RNC and PS domainIu_BC:for BroadCast domain
Metro Telworks: An Introductionwww.metrotelworks.com# / 13WCDMA vs. GSMWCDMAGSMCarrier spacing5 MHz200 kHzFrequency re-use factor11-18Power control frequency1500 Hz2 Hz or lowerQuality controlRadio resource management softwareNetwork planningFrequency diversity5 MHz bandwidth gives multipath diversity with RAKE receiverFrequency hoppingPacket dataLoad-based packet schedulingTime slot based scheduling with GPRSDownlink transmit diversitySupported for improving downlink capacityNot supported
Metro Telworks: An Introductionwww.metrotelworks.com# / 1313Symbol rate SF = Chip rate=3.84McpsFor UMTSSF of uplink channelization code4~256 SF of downlink channelization code: 4~512OVSF: Orthogonal Variable Spreading Factor OVSF CodeScrambling CodeDataSpread DataSpreading Process of UMTSSymbolChip3.84Mcps3.84Mcps
Metro Telworks: An Introductionwww.metrotelworks.com# / 13The actual process of spreading is done over two phases, channelization and scrambling. Either a 38400 chip scrambling code, or a shorter 256 chip scrambling code can be to used to scramble the data. The difference between these two approaches is that with the use of shorter codes, multi-user detection schemes can be used at the base station
Scrambling CodeUMTS Scrambling code is pseudo random binary sequenceIt has similar noise array character, seemingly random but with regularity. Can make the user data further random , strengthened by scrambling a code to keep secret the user data, at the same time easy to carry out multiple access communication.UMTS scrambling code is generated from Gold sequenceGold sequence has excellent self-correlation.Cross-correlation is very week between two codes. It is used to identify cell and user for multiple access.
Metro Telworks: An Introductionwww.metrotelworks.com# / 13Characteristic of Scrambling codeThere are 224 Uplink Scrambling Codes, they are used to distinguish different users in one cell. There are 218-1 Downlink Scrambling Codes, used to distinguish different cellsScrambling codes usually used are the first 8192 codes, which are code 018191. They are divided into 512 aggregationseach aggregation has 1 primary scrambling code (PSC) and 15 secondary scrambling codes (SSC).The 512 primary scrambling codes are divided further into 64 primary scrambling code groups , with 8 primary scrambling codes in each group.
Metro Telworks: An Introductionwww.metrotelworks.com# / 13Code FunctionsChannelization code ---- for separation of physical channels in the uplink and separation of users in the downlink
Scrambling code ---- for separation of users/terminals in the uplink and cells/sectors in the downlink.
Metro Telworks: An Introductionwww.metrotelworks.com# / 13Modulation Methods in UMTSBPSK (Binary Phase Shift Keying) in Uplink channlesQPSK (Quadrature Phase Shift Keying) in Downlink channels16QAM (16-state Quadrature Amplitude Modulation) in HSDPA
Metro Telworks: An Introductionwww.metrotelworks.com# / 13UMTS Channel Concept andFrame Structure
Metro Telworks: An Introductionwww.metrotelworks.com# / 13WCDMA Protocol stack OR WCDMA OSI modelPhysical channels (Code,frequency,etc)Logical channels(What is transmitted)Transport channels(How it is transmitted)Radio Resource Control (RRC)Physical LayerMedium Access Control (MAC)RLCRLCRLC
Metro Telworks: An Introductionwww.metrotelworks.com# / 1320Logical channel: directly bear user data Control channel Traffic channelTransport channel: services Physical layer provides for MAC layer Dedicated channel Common channelPhysical channel: the final embodiment of all kinds of informationtransferred in air interfaceAccording to protocol structure, WCDMA channels can be classified as:
Metro Telworks: An Introductionwww.metrotelworks.com# / 13Control Channel (Signaling)Broadcast Control Channel (BCCH)Paging Control Channel (PCCH)Dedicated Control Channel (DCCH)Common Control Channel (CCCH)Traffic Channel (User Data)Dedicated Traffic (DTCH)Common Traffic Channel (CTCH)LOGICAL CHANNELS1. Logical channels : Used for communication between Layer 3 (RRC) & Layer 2 (RLC/MAC). Depending on the information content ,logical channels are characterized into traffic & Control channels.
Metro Telworks: An Introductionwww.metrotelworks.com# / 1322Broadcast control channel ( BCCH) : Point to multipoint ,DLIt is a broadcasting channel that supplies all the UEs with basic cell and network parameters(eg. Frequency lists , code lists etc). Paging control channel(PCCH) : Point to multipoint ,DL It transports paging information. All the UEs are required to regularly read the information on the BCCH and on the PCCH Dedicated control channel (DCCH) : Point to point ,UL/DL DCCH is provided in parallel to a DTCH for point to point signaling during an active connection Common control channel ( CCCH) : Point to multipoint ,UL/DL It enables access by a UE to the UTRAN Control channels:
Metro Telworks: An Introductionwww.metrotelworks.com# / 1323Dedicated traffic channel (DTCH): Point to point ,UL/DLDTCH is used to transport user data from Node B to a specific UE and vice versa. This means it is dedicated to a specific subscriberCommon traffic channel (CTCH) : Point to multipoint ,DL It transfers dedicated user information for all , or a group of specified UEsTRAFFIC CHANNELS:
Metro Telworks: An Introductionwww.metrotelworks.com# / 1324Characterizes HOW data is transported over the air interface . Each transport channel is accompanied by the Transport format indicator(TFI). The physical layer combines the TFI information of different transport channels to the Transport format combination indicator(TFCI).It is not necessary to transmit the TFCI for fixed data rates.Organize & Pack data from different services from the higher layers for suitable transportationUnpack incoming data and sort for delivery to upper layersOffers flexible data speeds and channel encoding Efficient usage of radio resources
Transport Channels:
Metro Telworks: An Introductionwww.metrotelworks.com# / 1325DCH (Dedicated Channel)Bi-directional channel for transporting both dedicated user and control data; carries DTCH & DCCH.DCH is characterized by fast data rate change on a frame by frame basis. BCH (Broadcast Channel)Downlink; Transports BCCH to UE; Always transmitted using the same transport format in entire cellFACH (Forward Access Channel)Downlink; Transports small amount of data from BCCH/CCCH/DCCH/CTCH to either a specific UE or over the entire cellPCH (Paging Channel)Downlink; Transports data from PCCH to UE over entire cellRACH (Random Access Channel)Uplink; Used by UE for initial access to UTRANCPCH (Common Packet Channel)Uplink; Used by UE to send packet data to UTRANDSCH (Downlink Shared Channel)With DSCH, user may be allocated different data rates,For example:384kbps with SF 8and 192kbps with SF16.DSCH may be mapped to a multicode case,Ex-3channelisation codes with spreading factor 4 provide a DSCH with 2 MBPS. Dedicated Transport Channel Common Transport Channel
Metro Telworks: An Introductionwww.metrotelworks.com# / 1326Physical Channels :By varying the SF, physical layer matches transmission rate to the current transport channel data.
Actual data transmission over the air
Metro Telworks: An Introductionwww.metrotelworks.com# / 1327Physical Channels(1)The physical channel is in a 3-layer structure by the time: Superframe One superframe lasts 720ms, and consists of 72 radio frames.radio frameOne radio frame has a period of 10ms, and comprises 15 timeslots with the same length. Corresponding to 38400 chips, it is a basic unit of the physical layer.TimeslotA timeslot is a unit composed of a bit domain, corresponding to 2560 chips. The bit number and structure of a timeslot depends on the specific type of the physical channel.
Metro Telworks: An Introductionwww.metrotelworks.com# / 1328Definition of some terms:Bit: is 0 or 1 carried in the base band signal. each digit represents/denote one bitByte: 1 byte equal to bits,Symbol:is the unit used in modulation and demodulation. The information in bits goes through convolution encoding,repetition,interleaving and CRC correction, then becomes a symbol.Chip: it can be viewed as a conception of time duration.Physical Channels(2)The frame structure of the physical channels is shown:Tslot #1Tslot #2Tslot #ITslot #15Ttimeslot= 2560 chipFrame #0Frame #1Frame #IFrame #71Tframe=10 msTsuperframe=720 ms
Metro Telworks: An Introductionwww.metrotelworks.com# / 1329Uplink physical channel2 UL Dedicated physical channel (DPDCH and DPCCH)2 UL Common physical channel (PRACH and PCPCH)
UL Common physical channelUL Dedicated physical channel Dedicated physical Control channelDPCCHDedicated physicaldata channelDPDCHPhysical randomAccess channelPRACHPhysical common Packet channelPCPCH
Metro Telworks: An Introductionwww.metrotelworks.com# / 1330Uplink Dedicated physical channel
Metro Telworks: An Introductionwww.metrotelworks.com# / 1331There are two type of uplink dedicated physical channels, the uplink dedicated physical control channel and uplink dedicated physical data channel. They are I/Q code multiplexed in each timeslot. UL DPDCH is used to carry the DCH transport channel. There are maybe 0.1.or several DPDCHs on each radio link. UL DPCCH is used to carry L1 control information . Consists of known Pilot bit: support channel estimate for coherent detection ; TPC: power control command FBI: feedback information TFCI: inform the receiver about the transport format of the transport channel. There is one and only one uplink DPCCH on each radio link.Fig show the frame structure of ul dedicated physical channel . Each radio frame of length 10ms is spilt into 15 timeslots, each of length 2560 chips. There is 10*2k bits in per DPDCH timeslot, k=0,1~6, that corresponding to SF=256,128,~4. DPCCH used SF=256 to spread ,so the bits number is fixed. There is total 10 bits in per DPCCH timeslot.
PRACHPhysical Random Access Channel PRACH consists preamble part and message partRandom access transmit 1or more 4096 chips length preambles and 10ms or 20ms length message part.Message partPreamble4096 chips10 ms (one radio frame)PreamblePreambleMessage partPreamble4096 chips20 ms (two radio frames)PreamblePreamblePRACH transmitted structure
Metro Telworks: An Introductionwww.metrotelworks.com# / 1332Random access channel is typically used for signalling purpose, to register the terminal after power-on to the network; or to perform location update after moving from one location area to another location area ; or initiate a call. Sometimes RACH alse can be used to carry user data. It is intended for low data rate operation with packet data where continuous connect is not maintained.RACH is mapped on the Physical Random Access Channel. PRACH consists preamble part and message part. Just like the fig. random access transmit 1or more 4096 chips length preambles and 10ms or 20ms length message part.Preambles that are sent prior to data transmission. These use a spreading factor of 256 and contain a signature sequence of 16 symbols, resulting in a total length of 4096 chips for the preamble. Once the preamble has been detected and acknowledged with the Acquisition Indicator Channel (AICH), the 10ms (or 20ms) message part is transmitted.
Additive Links Online Hawaii Area ALOHA
PRACHPhysical Random Access Channel 10ms message part is split into 15 timeslots, each timeslot consists of 2560chips.Each timeslot includes data part and control part. They are transmitted in parallel . Data part :SF=32~256 , control part: SF=256.
Pilot Npilot bitsDataNdata bitsSlot #0Slot #1Slot #iSlot #14Tslot = 2560 chips, 10*2k bits (k=0..3)Message part radio frame TRACH = 10 msDataControlTFCI NTFCI bits
Metro Telworks: An Introductionwww.metrotelworks.com# / 133310ms message part is divided into 15 timeslots, the length of each timeslot =2560chips. Each timeslot consists of two parts : data message and control message. They adopt I/Q code multiplexing. Data part is used to mapping to transport channel .control part is used to transmitted L1 control message.There is 10*2k bits in data part. K=0,1,2,3. that corresponding to SF=256,128,64,32.The control part consists of 8 known pilot bits to support channel estimation for coherent detection and 2 TFCI bits. This corresponds to a spreading factor of 256 for the message control part Downlink physical channelDL physical channel include Dedicated physical channel1 Shared physical channel and five Common control channels.
DPCHSCHCPICHPICHAICHCCPCHPDSCHDL common physicalchannel
Metro Telworks: An Introductionwww.metrotelworks.com# / 1334Common Downlink Physical ChannelsP-CCPCH Common Control Physical Channel (Primary)Broadcasts cell site informationBroadcasts cell SFN; Timing reference for all DL32kps SF 256 continues transmissionSCH Synchronization ChannelFast Synch. P frame, S slot, time-multiplexed with P-CCPCHS-CCPCH Common Control Physical Channel (Secondary)Transmits idle-mode signaling and control information to UE sVariable rate, with DTXP-CPICH Common Pilot ChannelS-CPICH Secondary Common Pilot Channel (for sectored cells)PDSCH Physical Downlink Shared ChannelTransmits high-speed data to multiple usersDedicated Downlink Physical ChannelsDPDCH Dedicated Downlink Physical Data ChannelDPCCH Dedicated Downlink Physical Control ChannelTransmits connection-mode signaling and control to UE s
Downlink dedicated physical channel
Metro Telworks: An Introductionwww.metrotelworks.com# / 1335The downlink dedicated physical channel can be seen as a time-multiplex of a dl DPDCH and a dl DPCCH. DL DPDCH is used to carry dedicated user traffic generated at layer 2 or above.DL DPCCH is used to carry layer1 control information. Including :TPC, TFCI , Pilot.Fig show the frame structure of dl dedicated physical channel. Each frame of length 10ms is spilt into 15timeslot. Each of length of timeslot=2560chips.there is 10*2k bits in per timeslot, K=0~7,that corresponding to SF= 512~4.CPICH
Metro Telworks: An Introductionwww.metrotelworks.com# / 1336The CPICH is a fixed rate(30kbps,SF=256) downlink physical channel that carries a pre-defined bit sequence. It is a uncoded channel.Fig show the frame structure of CPICH. Each frame of length 10ms is spilt into 15 timelsots. Each length of timeslot =2560chips. There is fixed 20 bits in per timeslot.CPICHThere is 2 types of CPICH:P-CPICH and S-PICHP-CPICH: P-CPICH of different cell uses the same Cch,256,0 OVSF code to spread ,the bit rate of P-CPICH is also fixed. The P-CPICH is scrambled by the primary scrambling code. There is one and only P-CPICH per cell. The P-CPICH is broadcast over the entire cell. it is used to search cell primary scrambling code during cell selection procedure. And it is also used for measurement and estimation during handover, cell selection and cell re-selection.S-CPICH: A arbitrary channelization code of SF=256 is used for the S-CPICH. A S-CPICH is scrambled by either the primary or a secondary scrambling code. There may be 0,1 or several S-CPICH per cell. A S-CPICH may be transmitted over the entire cell or part of the cell. It is may be a phase reference for a dl DPCH, but it is decided by high layer signalling.
Metro Telworks: An Introductionwww.metrotelworks.com# / 13P-CCPCH
Metro Telworks: An Introductionwww.metrotelworks.com# / 1338The primary common control channel is a fixed rate(30kbps,SF=256) downlink physical used to carry BCH transport channel.It is scrambled by the primary scrambling code.Fig show the frame structure of PCCPCH, the frame structure differs from DPCH in that no TPC command, no TFCI and no Pilot bit to transmitted. The PCCPCH is not transmitted during the first 256 chips of each timeslot. During this period ,SCH(P-SCH and S-SCH) is transmitted.Some important measurements which physical layer must perform and report to RRC are : MeasurementExplanationModeEvaluationCPICH Ec/NoEnergy per chip/ RSSIIdle / ConnectedPeriodic Or Upon RequestCPICH RSCPReceived Signal Code PowerIdle / Connected
Periodic Or Upon Request
RSSIReceived Signal Strength IndicatorConnectedPeriodic Or Upon Request
TrCh BLEREstimate of BLER on Rx Transport channelConnected
Periodic Or Upon Request
UE TX PwrUE Transmit powerConnected
Periodic Or Upon Request
Metro Telworks: An Introductionwww.metrotelworks.com# / 13393G drive test analysis
Metro Telworks: An Introductionwww.metrotelworks.com# / 1340Coverage, dBmServing CPICH RSCPQuality, dBServing CPICH Ec/NoAccessibility (Call setup success rate), %Voice callVideo callPSRetainability(Call drop rate), %Voice callVideo callPSMobility (Handover success rate), %Soft handover success rate, CS voiceSoft handover success rate, CS videoSoft handover success rate, PSThroughput, kbpsR99 Mean data rate DL R99 Mean data rate UL HSDPA average throughputKey performance indicator, category
Metro Telworks: An Introductionwww.metrotelworks.com# / 13
Following are 3G drive test KPI we have to achieve
Stationary test for 3GAcceptance TestFunctionality Test During Swap night Benchmarking AcceptanceFinal AcceptanceSwapped TestMandatoryMandatoryMandatoryNew TestMandatoryMandatoryMandatory
Metro Telworks: An Introductionwww.metrotelworks.com# / 13KPITargetVoice Service - End to End1Assignment Setup Success Rate(CS)92.50%2PS call setup Success Rate93%3Call Drop Rate2%4Hard Handover success Rate93%5Soft Handover Success Rate99%6Inter-RAT CS Handover success Rate92%7Assignment Setup Delay(CS)
