CDMA2000 Principle ISSUE4.0
Page 2ObjectivesAfter this presentation, you will be familiar with: the development of mobile communication system the s...
Page 3Course OrganizationChapter 1: IntroductionChapter 2: CDMA Techniques & TechnologiesChapter 3: CDMA Air InterfaceChap...
Page 41stGeneration1980s (analog)2ndGeneration1990s (digital)3rdGenerationcurrent (digital)3G provides: Complete integrat...
Page 5Transmission TechniquesTraffic channels: differentusers are assigned uniquecode and transmitted overthe same frequen...
Page 6Standards for3G3G systemCDMA20003GPP2FDD modeWCDMA3GPPFDD modeTD-SCDMACWTSTDD modeIntroduction
Page 7A Comparison b/w 3G standardsWCDMA CDMA2000 TD-SCDMAReceiver type RAKE RAKE RAKEClose loop powercontrol Supported Su...
Page 8IS95A9.6kbpsIS95A115.2kbpsCDMA2000 307.2kbps Heavier voiceservice capacity ; Longer period ofstandby timeCDMA20003...
Page 9Frequency Allocation In CDMA2000Band Class 0 and Spreading Rate 1IntroductionTransmit Frequency Band (MHz)BlockDesi...
Page 10Frequency Allocation In CDMA2000Band Class 1 and Spreading Rate 1IntroductionTransmit Frequency Band (MHz)BlockDes...
Page 11CDMA2000 1XNetworkStructureMS: Mobile Station BTS: Base Transceiver StationBSC: Base Station Controller MSC: Mobile...
Page 12Course ContentsChapter 1 IntroductionChapter 2 CDMA Techniques & TechnologiesChapter 3 CDMA Air InterfaceChapter 4 ...
Page 13Correlation(a)Correlation 100% so thefunctions are parallelCorrelation 0% so thefunctions are orthogonalCDMA Techni...
Page 14Orthogonal Function Orthogonal functions have zero correlation. Two binary sequencesare orthogonal if their “XOR” ...
Page 15Information spreading overorthogonal codesCDMA Techniques & Technologies1 0 0 1 10110 0110 0110 0110 01101001 0110 ...
Page 16Information recovery CDMA Techniques & Technologies1 0 0 1 1+1-1Rx Data1001 0110 0110 1001 10010110 0110 0110 0110 ...
Page 17Spreading and De-spreadinginformation pulse interference White noiseThe improvement of time-domain information rate...
Page 18Signal flowInterleavingSourcecodingConvolution&InterleavingScrambling Spreading ModulationRFtransmissionSourcedecod...
Page 19Common Technical Terms Bit, Symbol, Chip: A bit is the input data which contain information A symbol is the outp...
Page 20In a typical duplex call, the duty ratio is less than 35%. To achievebetter capacity and low power consumption, bas...
Page 21Channel CodingConvolution code or TURBO code is used in channel encodingConstraint length=shift register number+1.E...
Page 22Turbo CodeTurbo code is used during the transmission of large data packet. Characteristics of the Turbo code: The...
Page 23InterleavingThe direction of the data stream1 2 873 64 51 2 873 64 51 2 873 64 51 2 873 64 51 2 873 64 51 2 873 64 ...
Page 24Out0 0 11 1 0Scrambling (M) sequence Two points are important here: Maximum number of shift register (N) Mask T...
Page 25Long Code The long code is a PN sequence with period of 242-1chips The functions of a long code: Scramble the fo...
Page 26PNaPNcPNbShort CodeCDMA Techniques & Technologies Short code is a PN sequence with period of 215chips Sequence wi...
Page 27Walsh CodeW2n=Wn WnWn WnW1=0W2=0 00 1W4 =0 00 10 00 10 00 1Walsh code64-order Walsh function is used as a spreading...
Page 28 In forward direction, each symbol is spread with Walsh code Walsh code is used to distinguish the user in forwar...
Page 29Variable Walsh codes64481632129600 19200 38400 76800 153600 307200 614400Data rate -bps-W01 =0W02=00W12=01W04=0000W...
Page 30Modulation-QPSKIQI channel PN sequence1.2288McpsQ channel PN sequence1.2288McpsBaseband filterBaseband filterCos(2p...
Page 31Power ControlHandoffDiversity and RAKECDMA Techniques & Technologies
Page 32PowerControlReverse power controlOpen loop power controlClosed loop power control− Inner loop power control: 800...
Page 33Reverse Open Loop PowerControl• The transmission power required by the mobile station is determined bythe following...
Page 34Reverse Closed Loop PowerControlBTSPower Control BitEb/Nt Value FER ValueInner Loop Power ControlOuter Loop Power C...
Page 35Forward PowerControl MS measures the frame quality and informs the base station to theresult i.e. whether it is in...
Page 36Forward Closed Loop PowerControl Compared with IS-95 system, CDMA2000 the forward quickpower control is fast.Power...
Page 37HandoffSoft handoffIt is a process of establishing a link with a target sector beforebreaking the link with the ser...
Page 38Soft/SofterHandoff• Multi-path combination in the BSC during soft handoff• Multi-path combination in the BTS during...
Page 39Pilot SetActiveSetCandidateSetNeighborSetRemainingSetThe pilot set, corresponding to the basestation being connecte...
Page 40T_ADD,T_DROP,T_TDROPTimeEc/IoSectorA SectorBGuard Time(T-TDROP)Add Threshold(T_ADD)DropThreshold(T_DROP)Soft Handof...
Page 41Comparison Thresholdt0 t1 t2Pilot P1Pilot P2Pilot P0T_COMP×0.5dBT_ADDPilot strengthP0-Strengh of Pilot P0 in Candid...
Page 42Transition Between Pilot SetsT_ADDT_DROPPilot 1PilotstrengthPilot 2T_TDROPNeighborSetCandidateSetActiveSetNeighborS...
Page 43Transmit Diversity Time diversity Block interleaving, error-correction Frequency diversity The CDMA signal ener...
Page 44Transmission Diversity The forward transmission diversity types in CDMA2000 1X are TD (Transmit Diversity)− OTD (...
Page 45Transmission DiversityThe Transmission Diversity Technology enhances the receive performance of MS.Transmissiondive...
Page 46The Principle of RAKE ReceiverRAKE antennas help to overcome on the multi-path fading and enhancethe receive perfor...
Page 47Course ContentsChapter 1 IntroductionChapter 2 CDMA Techniques & TechnologiesChapter 3 CDMA Air interfaceChapter 4 ...
Page 48Physical Channel in IS-95AForward channel Forward Pilot Channel Forward Sync Channel Forward Paging Channel For...
Page 49Pilot channel(all-zeros)W064Pilot ChannelA pilot channel: Assist mobile station to be connected with CDMA network...
Page 50ToQPSKcoder2.4kbps 4.8kbps 4.8kbpsCodesymbolRepetitivecodesymbol1.2kbpsConvolutionencoderr=1/2,K=9symbolrepetitionB...
Page 51ToQPSKcoderPagingchannel bitsPaging channel addressmaskLongcode PNgeneratordecimator1.2288McpsPaging Channel The p...
Page 52Forward Traffic ChannelCDMA Air InterfaceI Ch PN sequence (1.2288 Mcps)PN 1.2288 McpsRepetitivesymbol19.2kbps8.6kbp...
Page 53Reverse Access Channelused by MS to initiate communication or respond to Paging ChannelCDMA Air Interface4.8 kbps(3...
Page 54Reverse Traffic Channel CDMA Air Interfaceused to transmit data and signaling information8.6kbps9.6kbps4.8kbps2.4kb...
Page 55Initialization of the MS Synchronous Channel message contains the LC_STATE, SYS_TIME,P_RAT, and synchronizes with ...
Page 56CDMA2000 Forward ChannelForward CDMA2000 channelF-CACH F-CPCCH F-PICH F-CCCHF-DCCH F-FCHF-PC F-SCCH F-SCHF-PICH F-T...
Page 57Forward channelThese channels are newlydefined in CDMA2000 system.CDMA physical channels are classified in common c...
Page 58F-QPCH It transmits OOK-modulated signal which can be demodulated by MSsimply and rapidly. The channel adopts 80m...
Page 59F-SCH F-SCH is typically used for high speed dataapplications, while F-FCH is used for common voiceand low speed d...
Page 60F-DCCH It is used for the transmission of specific user signalinginformation during a call. Each forward traffic ...
Page 61Forward Radio Configuration (RC)Radio Configuration(RC):A set of Forward Traffic channel and Reverse Traffic Channe...
Page 62Reverse ChannelReverse CDMA2000 channelR-ACHR-TCHoperation(RC1~2)R-EACHoperationR-CCCHoperationR-SCCHR-FCHR-TCHoper...
Page 63Types of Reverse Channel Reverse channel includes reverse common channel and reversededicated channel. Reverse co...
Page 64MUX APilot( all 0s)Power Control BitN is the Spreading Rate numberPilot PowerControlPower Control Group= 1536 NPN C...
Page 65Reverse Channels Fundamental Channel: Fundamental Channel is used for the transmission of user informationto the ...
Page 66Reverse Radio Configuration (RC)RC: Radio ConfigurationRC1~RC2:IS-95A/BRC3~RC4:CDMA2000 1XRC5~RC6: CDMA2000 3xR...
Page 67RC 1RC 2RC 3RC 4RC 5RC 1RC 2RC 3RC 4RC 5RC 3RC 4RC 4RC 3F-FCHRCsR-DCCH/SCHRCsF-DCCH/SCHRCsR-FCHRCsRC Combination Re...
Page 68Course ContentsChapter 1 IntroductionChapter 2 CDMA Techniques & TechnologiesChapter 3 CDMA Air InterfaceChapter 4 ...
Page 69Definition of Coverage AreasLocation areaMSC areaPLMN areaService areaSectorareaCDMA Number PlanningCell area
Page 70Parameters InvolvedIn a CDMA system, the following parameters are defined toidentify a user and his location:MIN/I...
Page 71MIN/IMSIMobile subscriber identity/international mobile subscriber identityFor example, 0907550001/460030907550001N...
Page 72MDNCC + MAC + H 0H1H 2H 3 + ABCDInternational mobile subscriber DNNational valid mobile subscriber numberMobile dir...
Page 73ESNA unique Electronic Serial Number (ESN) is used to identify singleMS. An ESN includes 32 bits and has the follow...
Page 74TLDN+CC MAC H0H 1H2 ABC+ ++44Temporary local directory numberFor example, 8613344755001CDMA Number Planning
Page 75SID/NIDMSCID (Exchange Identity)= System Identity (SID) + Exchange number (SWIN)is used to represent a certain set ...
Page 76Location Area Identity (LAI) PAGING message is broadcast within a local area, the size of which depends ontraffic,...
Page 77Global Cell Identity (GCI) The unique ID of a cell in PLMN Format: LAI+CI CI: Cell Identity, a 2-byte-long hexad...
Page 78Sender Identification Number(SIN)MSC numberThe MSC number stipulated by Unicom is 460 + 03 + 09 + H0H1H2H3 +1000.HL...
Page 79Sub-System Number(SSN) SSN of MSC: 8 SSN of VLR: 7 SSN of HLR: 6 SSN of AC: 10 SSN of SMC: EE SSN of SCP: EF...
Page 80Review Chips rate: 1.2288Mcps IS-95A/B is a subset, RC1/RC2 Apply the coherent demodulation to the reverse pilot...
Page 81Why CDMA2000? Increase the system capacity Forward quick power control Forward transmit diversity: OTD,STS Cohe...
Page 82Why CDMA2000? Support high rate SCH, with the maximum rate of a singlechannel being up to 307.2kbps. Improve the ...
Page 83Summary Brief Development History of Mobile Communication Analog--digital--code division Objectives of 3G and co...
Page 84Questions What power control modes are there in CDMA2000 systemand how are they implemented? Describe the soft ha...
CDMA 2000 Principle Issue4.0
Upcoming SlideShare
Loading in …5
×

CDMA 2000 Principle Issue4.0

1,248
-1

Published on

the development of mobile communication system
the structure of CDMA2000 network
the number planning in CDMA2000 network
the techniques used by CDMA system including:
source coding, channel coding, interleaving, scrambling, spreading and modulation etc.
power control, soft handoff, RAKE receiver
F-PCH,F-PICH,F-SYNCH,F-FCH,F-SCH,R-ACH,R-PICH
Long code, short code and Walsh code
Chapter 1: Introduction
Chapter 2: CDMA Techniques & Technologies
Chapter 3: CDMA Air Interface
Chapter 4: CDMA Number Planning

Published in: Education, Technology, Business
1 Comment
0 Likes
Statistics
Notes
  • Be the first to like this

No Downloads
Views
Total Views
1,248
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
0
Comments
1
Likes
0
Embeds 0
No embeds

No notes for slide
  • AMPS Advanced Mobile station System (AMPS) uses 800MHz frequency band .It is widely used in North America, South America and some round-the-Pacific countries. TACS Total Access Communication System (TACS) uses 900MHz frequency band. There are two versions of TACS: ETACS (Europe) and NTACS (Japan). This standard is widely used in England, Japan and some Asian countries. GSM Global System of Mobile Communication (GSM) uses 900MHz frequency band and the system using 1800MHz frequency band is called DCS 1800. GSM originated from Europe and was designed as the TDMA standard of global digital cellular communication. GSM supports 64kbit/s data and can be interconnected with ISDN. GSM adopts FDD duplex mode and TDMA multiple access mode. Each carrier supports 8 channels and uses 200kHz bandwidth. IS-54 North America Digital Cell (IS-54) standard uses 800MHz frequency band and is also called D-AMPS. IS-54 is the earlier one in the two North America Digital Cell standards and is specified to use TDMA. IS-95 North America Digital Cell (IS-95) standard uses 800MHz frequency band or 1.9GHz frequency band. IS-95 is specified to use CDMA, which becomes the first choice of American PCS network. Currently, there are 54% license bearers using CDMA. CDMA One is the brand name of IS-95. CDMA2000 wireless communication standard evolves based on IS-95.
  • Frequency Division Multiple Access: frequency division, sometimes called channelization, means dividing the whole available spectrum into many single radio channels (transmit/receive carrier pair). Each channel can transmit one-way voice or control information. Under the control of the system, any user can be accessed to any of these channels. Analog cellular system is a typical example of FDMA structure. Similarly, FDMA can also be used in a digital cellular system,except that pure frequency division is not adopted. For example, FDMA is adopted in GSM and CDMA. Time Division Multiple Access means that the wireless carrier of one bandwidth is divided into multiple time division channels in terms of time (or called timeslot). Each user occupies a timeslot and receives/transmits signals within this specified timeslot. Therefore, it is called time division multiple access. This multiple access mode is adopted in both a digital cellular system and a GSM. TDMA is a complex architecture and the simplest case is that a single channel carrier is divided into many different timeslots, each of which transmits one-way burst-oriented information. The key part in TDMA is the user part, in which each user is allocated with one timeslot (allocated when a call begins). The user communicates with a base station in a synchronous mode and counts the timeslot. When his own timeslot comes, the mobile station starts a receiving and demodulation circuit to decode the burst-oriented information sent from the base station. Likewise, when a user wants to send any information, he should first cache the information and waits for his timeslot to come. After a timeslot begins, the information is transmitted at a double rate and next burst-oriented transmission begins to be accumulated. CDMA is a multiple access mode implemented by Spread Spectrum Modulation. Unlike FDMA and TDMA, both of which separate the user information in terms of time and frequency, CDMA can transmit the information of multiple users on a channel at the same time. That is to say,mutual interference between users is permitted. The key is that every information before transmission should be modulated by different Spread Spectrum Code-Sequence to broadband signal, then all the signals should be mixed and send. The mixed signal would be demodulated by different Spread Spectrum Code-Sequence at the different receiver.Because all the Spread Spectrum Code-Sequence is orthogonal,only the information that was be demodulated by same Spread Spectrum Code-Sequence can be reverted in mixed signal.
  • Development motivation of CDMA2000 EV: Voice and high-speed packet data have different QoS requirements: Voice: low-speed, symmetric, low-speed burst Data: high-speed burst, asymmetric, lower BER requirements When evolving into high-speed packet data services, CDMA2000 system minimizes the influence on a base station system and terminal system. Evolution process of CDMA2000 EV: phase 1: 1XEV-DO ( Data Only / Data Optimized ) Providing the support for packet data services alone instead of real-time voice services. phase 2: 1XEV-DV ( Data and Voice ) Providing non-real time packet data services and real-time voice services
  • Mobile Station (MS) The MS is the mobile subscriber equipment, which can originate and receive calls and communicate with the BTS. Base Transceiver Station (BTS) The BTS transmits and receives radio signals, realizing communication between the radio system and the mobile station. Base Station Controller (BSC) The BSC implements the following functions: Base Transceiver Station (BTS) control and management, call connection and disconnection, mobility management, stable and reliable radio link provision for the upper-layer services by soft/hard handoff, power control, and radio resource management. Packet Control Function (PCF) The PCF implements the R-P connection management. Because of the shortage of radio resources, some radio channels should be released when subscribers do not send or receive data, but the PPP connection is maintained continuously. The PCF can shield radio mobility for the upper-layer services via handoff. Packet Data Service Node (PDSN) The PDSN implements the switching of packet data services of mobile subscribers. One PDSN can be connected to multiple PCFs. It provides the interface between the radio network and the packet data network. Home Agent (HA) The agent locates at the place where the Mobile Node open its account, receive the registration information from MN. Similar as HLR in mobile network. Broadcast the accessible information of MN. Setup the tunnel between FA&HA. Transfer the data from other computer to the MN via the tunnel. Mobile Switching Center (MSC) The MSC implements the service switching between the calling and called subscribers. One MSC is connected with multiple BSCs. The MSC can also be connected to the PSTN, ISDN or other MSCs. It provides the interface between the radio network and PSTN. Visitor Location Register (VLR) It is a dynamic database, stores the temporary information (all data necessary to set up call connections) of the roaming subscribers in the local MSC area. VLR is used to store the subscriber information of all the MSs in its local area, which can be used to establish the incoming/outgoing call connections, to support basic services, supplementary services and mobility management. Home Location Register (HLR) It is a database for mobile subscriber management, the HLR (Home Location Register) is responsible for storing subscription information (telecom service subscription information and subscriber status), MS location information, MDN, IMSI (MIN), etc. The AC (Authentication Center) is physically combined with the HLR. It is a functional entity of the HLR, specially dedicated to the security management of the CDMA system. It stores the authentication information. It also prevents unauthorized subscribers from accessing the system and prevents the radio interface data from being stolen.
  • Correlation is measure of similarity of any tow arbitrary signals. It is computed by multiplying the tow signals and then summing (integrating) the result over a defined time windows. The two signals of figure (a) are identical and therefore their correlation is 1 or 100 percent. In figure (b) , however, the two signals are uncorrelated, and therefore knowing one of them does not provide any information on the other.
  • The principle behind spreading and despreading is that when a symbol is XORed with a known pattern, and the result is again XORed with the same pattern, the original symbol is recovered. In other words, the effect of an XOR operation if performed twice using the same code is null. In orthogonal spreading, each encoded symbol is XORed with all 64 chips of the Walsh code.
  • By spreading ,each symbol is XORed with all the chips in the orthogonal sequence (Walsh Sequence) assigned to the user. The resulting sequence is processed and is then transmitted over the physical channel along with other spread symbols. In this figure, a 4-digit code is used. The product of the user symbols and the spreading code is a sequence of digits that must be transmitted at 4 times the rate of the original encoded binary signal.
  • The receiver despreads the chips by using the same Walsh code used in the transmitter. Notice that under no-noise conditions, the symbols or digits are completely recovered without any error. In reality, the channel is not noise-free, but cdma system employ Forward Error Correction techniques to combat the effects of noise and enhance the performance of the system. When the wrong Walsh sequence is used for despreading, the resulting correlation yields an average of zero. This is a clear demonstration of the advantage of the orthogonality property of the Walsh codes. Whether the wrong code is mistakenly used by the target user or other users attempting to decode the received signal, the resulting correlation is always zero because of the orthogonality property of Walsh sequences.
  • The processing gain is calculated as follows: 10*log 10 128=21db
  • Adopted in CDMA system is a QCELP vocoder with variable rates, which is actually a device converting a sound signal into the signal which can be transmitted in a circuit. The method adopted generally in a wire communication system is to first sample (8,000 sample values generated per second) a voice signal with a 8KHZ signal and then implement 8-bit quantization coding for each sample value. Therefore, each voice channel in a wired system has the rate of 64K. However, because the air resource in a wireless system is very precious, a more effective coding mode is needed to use a rate as low as possible in the case where voice quality is guaranteed. QCELP vocoder with variable rates is such a device. The main principles of it are to extract some voice feature parameters when a person speaks and transmit these feature parameters to the peer party. Then,the peer party will recover the voice with these parameters based on the promise between the two parties. Thus, a far lower rate is needed. Let’s give an example. The information of a triangle can be transmitted from one place to another in two ways: one is to obtain some points by means of sampling and transmit the information of these points to the peer party. The two parties connect these points to obtain a triangle. The other is to transmit the length of a side and the degrees of two angles of this triangle to the peer party, who can likewise recover this triangle based on these pieces of information. Obviously, there is far less information to be transmitted in the second method. What a vocoder does is similar to the latter method, but what a vocoder actually does is more complex than this. But the principles are the same. Meanwhile, the codes transmitted from the transmit end to the receive end and describing voice feature parameters vary with the rhythm or loudness of a speech. In summary, variable rates mean that a vocoder can change its own code rates based on the loudness or rhythm of a speech to further reduce a code rate. Thus, a code with a higher rate will be adopted when there is a high voice while a code with a lower rate will be adopted when there is a low voice. In a silent period (when a person makes no sound during a speech), the lowest code rate will be adopted. Thus, a code rate can be decreased to reduce the interference with other users.
  • convolution code is an error correcting code. Convolution aims to associate a previous signal with a subsequent one and the association of the previous signal and the subsequent one actually means that this signal is capable of detecting and/or correcting an error. Error correcting or error detecting certainly will increase some redundancy signals, therefore the output bit rate increases to 3 times that at the input terminal of a convolution encoder.
  • It can be seen from the figure that the data are read row by row into an interleaver at the transmit end,read column by column out (this process is called interleaving) and propagated after other modulation process. Then, the data enter the interleaver at the receive end row by row and are read out column by column (this process is called de-interleaving). Currently, we assume that in the course of propagation, when row 2 data are transmitted, consecutive error codes occur to the 2nd, 3rd and 4th bits as a result of fading or other reasons, as shown by the left side of the figure. If the original data had been transmitted after the interleaving, the second bit of row 2 ,the second bit of row 3 and the second bit of row 4 would have been error codes after being read out column by column at the receive end. Because common error correcting codes can very easily process discrete error codes, the receive end can very easily recover the signals after the anti-interleave into the original signals by means of error correcting,but always cannot recover those signals not interleaved as a result of consecutive error codes. Therefore, the interleave can overcome fast fading caused during the signals transmission in air. The interleave code seldom functions in correcting error codes caused by slow fading, because slow fading may result in long consecutive error codes,even the whole frame may be error.Therefore, there will occur consecutive error codes after de-interleaving . The above figure is the simplest interleave and the interleave in an actual application is far more complex.
  • In CDMA system, user information is encrypted by means of scrambling. The scramble code used here is M-sequence. Shown in the figure is an M-sequence generator made up of a shifting register sequence and a mask. The period of the output sequence is 2 N -1 (N being the number of shifting registers). That is to say, the shifting register sequence resumes to the initial status when every 2 N -1 pieces of codes are output. In a CDMA system, there are two kinds of M-sequence, one being the long code with its period of 2 42 -1 and the other being the short code with its period of 2 15 -1. Used for scrambling is the long code while used for subsequent demodulation is the short code. It can be seen that for different masks, a shifting register sequence outputs different M-sequences, which we call different phases. Actually, different masks in CDMA are allocated to different users,who are enabled to obtain different M-sequences.
  • In a reverse direction, different long codes are used for the information sent by different users and these are known to the base station and these users. Thus, the base station can identify different mobile stations.
  • 1 0 1 0 1 1 0 1 1 0 1 0 1 1 0 1 ……. PNa PNb PNc
  • Orthogonal codes are easily generated by starting with a seed of 0, repeating the 0 horizontally and vertically, and then complementing the 1 diagonally. This process is to be continued with the newly generated block until the desired codes with the proper length are generated. Sequences created in this way are referred as “Walsh” code. The Walsh code is used to separate the user in the forward CDMA link. In any given sector, each forward code channel is assigned a distinct Walsh code.
  • Enhancements of CDMA2000 include the use of Walsh spreading factor to attain high data rates on the forward link. Variable Walsh spreading uses the tree structure for recursively constructing Walsh codes of the longer lengths. Higher data rates for the user can be obtained by using the shorter Walsh code. However ,use of one of the shorter codes precludes using any longer code that are derived from it.
  • In an actual application, the system implements the modulation in this way: as shown above, I and Q channel sequences in the figure represent two channels of cyclic PN short code sequences. The cyclic period of each channel of PN short codes is 2 15 . For different sectors, there are different starting locations of I and Q sequence cycles (that is to say, different sectors have different time offsets). In this way, different PN short code sequences can be obtained and a mobile station can recognize the information from different sectors.
  • Reverse open loop power control means that based on the detected signals from a base station, a mobile station makes a preliminary judgement of the attenuation of an air path and specifies what transmitting power should be used to transmit signals. If the mobile station receives strong signals, it shows there is weak air attenuation and the mobile station transmits signals at a smaller power. If the mobile station receives weak signals, it shows there exists strong air attenuation and the mobile station will transmit signals at a greater power. Reverse closed loop power control means that after receiving a signal from a mobile station , a base station will judge its strength. If the signal is higher than the threshold needed by the base station, the base station sends an instruction that the mobile station should decrease the transmitting power. If the signal is lower than the threshold needed by the base station, the base station sends an instruction that the mobile station should increase its transmitting power. Forward power control is similar to reverse power control, but the former controls the signals a base station transmits to various users.
  • Inner loop power control The base station compares the measured Eb/Nt with the corresponding objective and the mobile station will be ordered to decrease the transmission power if the measured Eb/Nt exceeds the objective. Otherwise, the mobile station will be ordered to increase the transmission power. The adjustment frequency is 800HZ. Outer loop power control Estimate Eb/Nt objective based on the measured Frame Error Rate(FER) Eb/Nt=bit energy/density of interference power spectrum, similar to signal-to-noise ratio.
  • During the communication of the mobile station, the mobile station measures the Eb/Nt value of the received forward traffic channels, compares them with the threshold and orders the base station to increase or decrease the transmission power to keep constant the traffic channel Eb/Nt of whole-rate services.
  • Soft handoff means that during the handoff of a mobile station at the coverage edge areas of two or multiple base stations, the mobile station receives the signals from multiple base stations (two in most cases) at the same time and the base stations receive the signals from this mobile station at the same time. The mobile station will not disconnect from the original base station until some conditions are satisfied. The reasons for soft handoff are as follows: 1. CDMA system can implement the frequency multiplexing of adjacent cells with the same frequency. 2. For each channel, the mobile station and base station adopt multiple RAKE receivers to receive multi-path signals at the same time. In the course of soft handoff, the signals from various base stations, for a mobile station, are equal to multi-path signals and the receiving of these signals by the mobile station is equal to a kind of space diversity. This soft handoff or softer handoff can improve the quality of service during the handoff in a real sense. That is to say, the conversation quality at the coverage edge is improved and the call dropping rate greatly reduced. This is not common commercial propagation, but a fundamental solution because call dropping in a GSM system mostly takes place during the handoff.
  • Pilot Detection Threshold (T_ADD) Any Pilot that is strong but is not in the Handoff Direction Message is a source of interference. This Pilot should be immediately moved into the active set for handoff to avoid voice/data degradation or a possible drop call. T_ADD affects the percentage of MS in handoff. It should be low enough to quickly add useful Pilots and high enough to avoid false alarms due to noise. Pilot Drop Threshold (T_DROP) This affects the percentage of MS in handoff. It should be low enough to avoid dropping a good Pilot that goes into a short fade . It should be high enough not to remove quickly useful Pilots in the active or candidate state. Pilot Drop Timer (T_TDROP) This is a timer. Whenever the strength of a Pilot in the active set falls below a value of T_DROP, a timer is started by the MS. If the Pilot strength goes back above T_DROP, the timer is reset; otherwise the timer expires when a T_TDOP has elapsed since the Pilot strength has fallen below T_DROP. Every MS maintain a handoff drop timer for each Pilot in the Active and Candidate Sets.
  • The Comparison Threshold: T_COMP An additional parameter, T_COMP, is used to control handoff signaling. When the strength of a new Pilot exceeded the strength of the current serving Pilot by the amount of the comparison threshold, the MS will signal the BTS.
  • This graph illustrates the soft handoff process. The steps shown in this diagram are: Pilot 2>T_ADD.MS sends PSMM (Pilot Strength Measurement Message) and adds Pilot 2 to the Candidate Set. Pilot 2>Pilot1+T_COMP*0.5. MS sends another PSMM. BTS decides to add Pilot 2 to the Active Set and sets up the soft handoff. MS receives message and moves Pilot 2 to the Active Set. Pilot 1<T_DROP. MS starts handoff drop timer for Pilot 1. Drop timer expires. MS sends PSMM indicating that Pilot 1 should be dropped. MS receives message indication that Pilot 1 has been dropped and moves Pilot 1 to the Neighbor Set.
  • Diversity technology means that after receiving two or more input signals with mutually uncorrelated fading at the same time, the system demodulates these signals and adds them up. Thus, the system can receive more useful signals and overcome fading. A mobile communication channel is a multi-path fading channel and any transmitted signal reaches a receive end by means of multiple transmission paths, such as direct transmission, reflection, scatter, etc. Furthermore, with the moving of a mobile station, the signal amplitude, delay and phase on various transmission paths vary with time and place. Therefore, the levels of received signals are fluctuating and unstable and these multi-path signals, if overlaid, will lead to fading. The mid-value field strength of Rayleigh fading has relatively gentle change and is called “Slow fading”. And it conforms to lognormal distribution. Diversity technology is an effective way to overcome overlaid fading. Because it can be selected in terms of frequency, time and space, diversity technology includes frequency diversity, time diversity and space diversity.
  • As stated previously, a long code is used for scrambling. However, a long code has too long a period, which cannot be wholly used for scrambling. We can only sample some chips of a long code at some point of time and use them as the sequences of scrambling. This requires that a mobile station should know the following information: when the long code chip used for scrambling begins, what the mask of a generated long code is, etc. All these pieces of information are so-called long code synchronization.
  • Symbol repetition makes symbol streams at different rates adapted to those at the rate of 19.2k. The original symbol stream at the rate of 19.2Kbps will not be repeated, 9.6Kbps symbol stream will be repeated once, 4.8Kbps symbol stream will be repeated twice…. Then, after the interleaving, long code scrambling, spreading, etc., the transmitting power of repeated bits is reduced during the transmission. Thus, variable rates can be achieved and the system capacity be increased. During the long code scrambling, one chip will be sampled from every 64 long code chips for exclusive-or with a scrambled chip. A forward traffic channel includes a power control sub-channel and a power control bit is used to instruct an MS to increase or decrease the transmitting power. Each forward traffic channel frame (20ms) can be divided into 16 power control groups (each group is 1.25ms long). Each power control group contains a power control bit , therefore the rate of reverse fast power control is 16* (1s/20ms)=800bps. And the power control bit is embedded right during the long code scrambling.
  • Note that a reverse channel is first spread with WALSH to 307.2Kbps and then becomes 1.2288Mcps after long code modulation. The long code here not only spreads spectrum, but implements the function of channelization. “Data burst randomizer” means discarding repeated chips during the transmission according to a certain algorithm and implementing discontinuous transmission so as to reduce the transmission rate and increase the capacity of reverse channels. In OQPSK reverse modulation, as opposed to the data modulated by I channel PN sequence, the data modulated by Q channel PN sequence has the delay of half a PN chip (406.901ns). Thus, the maximum phase change of four-phase modulation is 90 degrees instead of 180-degree mutation.
  • LC_STATE is LongCode State SYS_TIME is system time. Search for the CDMA carrier, acquire the Pilot Channel and synchronize the short code. Receive the Synchronous Channel message containing the LC_STATE, SYS_TIME, P_RAT, acquire timing and synchronize with the system. Monitor the Paging Channel and receive the system message. The MS can register on the Access Channel .
  • The new types of pilot channels are introduced to support the new features of CDMA2000: F-TDPICH (Forward Transmit Diversity Pilot Channel) F-APICH(Forward Auxiliary Pilot Channel) F-ATDPICH (Forward Auxiliary Transmit Diversity Pilot Channel ) Now we will have a further discussion about them. F-PICH Function: Pilot channel messages are transmitted to all the mobile stations within the coverage of the base station at all times. Provide channel gains and phase estimation. Detect multi-path signals Capture the cell forward channel and handoff F-TDPICH Function: Support transmit diversity and work together with F-PICH. F-APICH F-ATDPICH Function: Beam shaping Supporting the application of a smart antenna Three new types of forward common channels are introduced into CDMA2000 to substitute for F-PCH: F-BCCH (Forward Broadcast Control Channel) F-QPCH (Forward Quick Paging Channel F-CCCH (Forward Common Control Channel) These channels are utilized to transmit messages from the base station to the mobile station, such as a paging message. Some of the functions are identical to those of the paging channel, but they are characteristic of a higher data rate and higher reliability. Now we will have a further discussion. F-BCCH Characteristics: The F-BCCH is utilized by the base station to transmit the overhead information which is transmitted on F-PCH in IS-95 system and broadcast information. The F-BCCH can work in the discontinuous mode. And it can be transmitted repeatedly while working in a slow transmit data rate. This reduces the transmit power. Function: With F-BCCH transmitted repeatedly, a mobile station achieves the time diversity gain by combining the repeated information. Thus, the base station can enhance the overall capacity of forward channels by reducing the transmission power . Q-PCH Characteristics: A quick paging channel is an OOK-modulated signal which can be demodulated by a mobile station simply and rapidly. The channel adopts 80ms as a QPCH timeslot. Each such timeslot can be divided into paging indicators, configuration change indicators and broadcast indicators, all of which are utilized to inform the mobile station whether to receive paging message, broadcast message or system parameters in the next F-CCCH or F-PCH. Function: Rapid and simple demodulation makes it unnecessary for the mobile station to monitor F-PCH for a long time, so the standby time is prolonged.
  • In a cell mobile communication network, there are many base stations and a mobile station has no fixed position. No matter where a mobile user in a service area moves, a mobile communication network must have the function of switching control so as to achieve such performance as location update, handoff and automatic roaming. In the mobile communication network architecture made up of a CDMA system, the definition of an area is shown in the figure. Service area A service area refers to the area where a mobile station can obtain services, namely, the area where the users in different communication networks (PLMN, PSTN or ISDN) can communicate with a mobile station without knowing its actual location. A service area may be made up of one or more Public Land Mobile Network (PLMN) and may be a country, part of a country or many countries. PLMN PLMN area is a geographic area where a PLMN provides communication services. PLMN can be considered as the extension of a network (such as ISDN or PSTN). One PLMN area may be made up of one or more Mobile Switching Centers (MSC). Within this area, there are common numbering systems (for example, the same national area code) and common routing plans. MSC forms the function interface between a fixed network and a PLMN and is used for call connection. MSC area An MSC area is part of the PLMN made up of the areas covered by all the cells controlled by an MSC. An MSC area can be made up of one or more location areas. Location area A location area refers to an area where a mobile station can move arbitrarily without any location update. A location area may be made up of one or more cells (or base station area). Paging signals can be transmitted simultaneously from all base stations in a location area to call a mobile station. Base station area An area covered by all cells included by one or more Base Transceiver Stations (BTS) located in the same base station point. Cell A wireless coverage area identified with a base station identification number or cell global identification. When an omni antenna is adopted, a cell is a base station area. Sector The area covered by a directional antenna in a base station is called a sector.
  • IMSI is the only number to identify a mobile user in a CDMA digital public land cellular mobile communication network. This code is valid to all location including a roaming area. IMSI adopts E.212 coded system. IMSI is stored in the mobile station/UIM card, HLR and VLR and transmitted on a wireless interface and MAP interface. Unicom uses MIN-based IMSI. IMSI is a 15-digit decimal number and its number structure is shown in the figure. MCC: Mobile Country Code, 460 for China. MNC: Mobile Network Code , 03 used in Unicom CDMA. MSIN: Mobile Subscriber Identification Number, a 10-digit decimal number. Unicom requires that MIN is the latter 10 digits of an IMSI, namely, MSIN. For the users of in the original Great Wall network in Unicom, the MSIN number structure is shown below: 3 + H 1 H 2 H 3 + ABCDEF H 1 H 2 H 3 equals that in a MDN. ABCDEF is obtained after the scrambling of ABCD in a MDN. For new Unicom users, MSIN is the IRM number resource obtained by China Unicom. Unicom first uses the number segment between 09 1000 0000 and 09 4999 9999 and the number structure is as follows: 09 + M 0 M 1 M 2 M 3 +ABCD M 0 M 1 M 2 M 3 : the same as the H 0 H 1 H 2 H 3 in a MDN. (Note: in the number segment first used by Unicom, M 0 M 1 M 2 M 3 may be the same as H 0 H 1 H 2 H 3 . Because the IRM number obtained by China Unicom is a discontinuous number segment. In the number segment used at a late time, M 0 M 1 M 2 M 3 and H 0 H 1 H 2 H 3 are different. ABCD: user number, to be obtained based on the scrambling of ABCD in a MDN in a certain mode, the scrambling mode to be defined by Unicom headquarters.
  • MDN is the number the caller needs to dial when a mobile user in home network is the called. MDN adopts E.164 coded system. MDN is stored in HLR and VLR, and transmitted on an MAP interface. The structure of a MDN is shown in the figure. CC: country code, 86 used in China. MAC: Mobile Access Code, network number plan adopted in home network, 133 used in China. H 0 H 1 H 2 H 3 : HLR identity number, allocated by Unicom headquarters on a uniform basis. ABCD: mobile user number, allocated by various HLRs. H 0 H 1 H 2 H 3 China Unicom allocation plan: This allocation plan takes into consideration IRM (international roaming MIN) number resource and user development prediction controlled by China Unicom. In actual applications, the starting point should be H 0 equal to 0~9 and MDN can be gradually used. Currently, the number segment with H 0 equal to 0 is used by users in the original Great Wall network and includes TLDN number and user number. For allocation arrangement, refer to the requirements of the Great Wall network. The numbers with H 0 equal to 1~9 are used new users. The allocation plan of H 0 H 1 H 2 H 3 is decided by Unicom headquarters on a uniform basis.
  • TLDN is a number temporarily allocated by the VLR of the visiting office to a visiting mobile user for the sake of network routing when a call is made to a mobile user. TLDN is part of a mobile user MDN and its number structure is shown in the figure: CC: country code, 86. MAC: mobile access code, 133. H 0 H 1 H 2 : identify a certain MSC/VLR. ABC: defined by MSC/VLR itself.
  • In a CDMA network, a mobile station judges whether roaming takes place based on a pair of identity numbers (SID and NID). System Identity Number (SID) includes 15 bits. Unicom first uses 512 numbers (3600~37FF) with bit 14~bit 9 being 110010. Each local mobile network is allocated with one SID and the specific number allocated to each local network is specified by Unicom headquarters. Network Identity Number is made up of 16 bits, with 0 and 65535 reserved. 0 is used to represent those base stations in a certain SID area not belonging to a specific NID area. 65535 is used to indicate that a mobile user can roam in the whole SID area. For a CDMA network side, there is no concept of NID, but an exchange number (one byte), which is used to identify the network equipment where a user is located.
  • In all messages, the GTI at the SCCP layer is set as 4. When a mobile station roams to a new visiting MSC, the visiting MSC sends messages (registration message and registration authentication message) to HLR for the first time. The caller GT at the SCCP layer of this message is set as the MSC number of this MSC, with TT set as 0. The called GT at the SCCP layer is set as the IMSI number of a mobile station, with TT set as 0. When a mobile station is called, the originating MSC sends messages to HLR. The caller GT at the SCCP layer of this message is set as the MSC number of this originating MSC, with TT set as 0. The called GT at the SCCP layer is set as the MDN number of the called mobile station, with TT set as 0. When a mobile station sends a short message, the message can be transferred by the MC where the caller mobile station belongs to. The called GT at the SCCP layer of this message sent to the MC is set as the MDN number of the mobile station, with TT set as 128. The caller GT is set as the MSC number of the caller mobile station service MSC, with TT set as 0. In all messages, the GTI at the SCCP layer is set as 4.
  • CDMA 2000 Principle Issue4.0

    1. 1. CDMA2000 Principle ISSUE4.0
    2. 2. Page 2ObjectivesAfter this presentation, you will be familiar with: the development of mobile communication system the structure of CDMA2000 network the number planning in CDMA2000 network the techniques used by CDMA system including:source coding, channel coding, interleaving, scrambling,spreading and modulation etc.power control, soft handoff, RAKE receiverF-PCH,F-PICH,F-SYNCH,F-FCH,F-SCH,R-ACH,R-PICH Long code, short code and Walsh code
    3. 3. Page 3Course OrganizationChapter 1: IntroductionChapter 2: CDMA Techniques & TechnologiesChapter 3: CDMA Air InterfaceChapter 4: CDMA Number Planning
    4. 4. Page 41stGeneration1980s (analog)2ndGeneration1990s (digital)3rdGenerationcurrent (digital)3G provides: Complete integrated servicesolutions High bandwidth Unified air interface Best spectral efficiency and……………… a step towards PCSAMPSAnalog to DigitalTACSNMTOTHERSGSMCDMAIS95TDMAIS-136PDCUMTSWCDMACDMA2000TD-SCDMADevelopment of Mobile CommunicationsIntroductionVoice to Broadband
    5. 5. Page 5Transmission TechniquesTraffic channels: differentusers are assigned uniquecode and transmitted overthe same frequency band,for example, WCDMA andCDMA2000FDMATraffic channels: different frequency bandsare allocated to different users,for example,AMPS and TACSTraffic channels: different time slotsare allocated to different users, forexample, DAMPS and GSMFrequencyTimePowerFrequencyTimePowerFrequencyTimePowerTDMACDMAUserUserUserUserUserUserIntroduction
    6. 6. Page 6Standards for3G3G systemCDMA20003GPP2FDD modeWCDMA3GPPFDD modeTD-SCDMACWTSTDD modeIntroduction
    7. 7. Page 7A Comparison b/w 3G standardsWCDMA CDMA2000 TD-SCDMAReceiver type RAKE RAKE RAKEClose loop powercontrol Supported Supported SupportedHandoff Soft/hard handoffDemodulationmodeCoherentChip rate (Mcps) 3.84 N*1.2288 1.28Transmissiondiversity modeTSTD, STTDFBTDOTD, STS NoSynchronizationmodeAsynchronous Synchronous AsynchronousCore network GSM MAP ANSI-41 GSM MAPCoherentCoherentSoft/hard handoffSoft/hard handoffIntroduction
    8. 8. Page 8IS95A9.6kbpsIS95A115.2kbpsCDMA2000 307.2kbps Heavier voiceservice capacity ; Longer period ofstandby timeCDMA20003XCDMA20001X EV1X EV-DO1X EV-DV1995 199820002003Development of CDMA Higher spectrum efficiency and network capacity Higher packet data rate and more diversified services Smooth transit to 3GIntroduction
    9. 9. Page 9Frequency Allocation In CDMA2000Band Class 0 and Spreading Rate 1IntroductionTransmit Frequency Band (MHz)BlockDesignatorCDMA ChannelValidityCDMAChannelNumberMobile Station Base StationA(10MHz) Valid 1-311 825.030-834.330 870.030-879.330B(10MHz) Valid 356-644 835.680-844.320 880.680-889.320A’(1.5MHz) Valid 689-694 845.670-845.820 890.670-890.820B’(2.5MHz) Valid 739-777 847.170-848.310 892.170-893.310The transmit frequence point for Base Station is computed by:F=870+N*0.03N: CDMA Channel Number
    10. 10. Page 10Frequency Allocation In CDMA2000Band Class 1 and Spreading Rate 1IntroductionTransmit Frequency Band (MHz)BlockDesignatorCDMAChannelValidityCDMAChannelNumberMobile Station Base StationA(15MHz) Valid 25-275 1851.250-1863.750 1931.250-1943.750D(5MHz) Valid 325-375 1866.250-1868.750 1946.250-1948.750B(15MHz) Valid 425-675 1871.250-1883.750 1951.250-1963.750E(5MHz) Valid 725-775 1886.250-1888.750 1966.250-1968.750F(5MHz) Valid 825-875 1891.250-1893.750 1971.250-1973.750C(15MHz) Valid 925-1175 1896.250-1908.750 1976.250-1988.750The transmit frequence point for Base Station is computed by:F=1930+N*0.05N: CDMA Channel Number
    11. 11. Page 11CDMA2000 1XNetworkStructureMS: Mobile Station BTS: Base Transceiver StationBSC: Base Station Controller MSC: Mobile Switching CenterHLR :Home Location Register VLR: Visitor Location RegisterPCF: Packet data Control Function PDSN: Packet Data Service NodeHA: Home Agent FA: Foreign AgentSCP: Service Control Point Radius: Remote Authentication Dial-in User ServiceAbisA1(Signaling)A2(Traffic)A11(Signaling)A10(Traffic)A3(Signaling &Traffic)A7(Singaling)Introduction
    12. 12. Page 12Course ContentsChapter 1 IntroductionChapter 2 CDMA Techniques & TechnologiesChapter 3 CDMA Air InterfaceChapter 4 CDMA Number Planning
    13. 13. Page 13Correlation(a)Correlation 100% so thefunctions are parallelCorrelation 0% so thefunctions are orthogonalCDMA Techniques & Technologies+1-1+1-1(b)+1-1+1
    14. 14. Page 14Orthogonal Function Orthogonal functions have zero correlation. Two binary sequencesare orthogonal if their “XOR” output contains equal number of 1’sand 0’s000001010101EXAMPLE:CDMA Techniques & Technologies101001011111
    15. 15. Page 15Information spreading overorthogonal codesCDMA Techniques & Technologies1 0 0 1 10110 0110 0110 0110 01101001 0110 0110 1001 1001User InputOrthogonalSequenceTx Data+1-1+1-1
    16. 16. Page 16Information recovery CDMA Techniques & Technologies1 0 0 1 1+1-1Rx Data1001 0110 0110 1001 10010110 0110 0110 0110 01101111 0000 0000 1111 1111Correct Function? ? ? ? ?Rx Data1001 0110 0110 1001 10010101 0101 0101 0101 01011100 0011 0011 1100 1100Incorrect Function
    17. 17. Page 17Spreading and De-spreadinginformation pulse interference White noiseThe improvement of time-domain information rate means that the bandwidth of spectrum-domaininformation is spread.S(f) is the energy density.fS ( f )The spectrum before spreadinginformationf0The spectrum before despreadinginformationInterference/noiseS ( f )f0 f f0The spectrum after despreadinginformationInterference/noiseS ( f )fThe spectrum after spreadinginformationf0S ( f )fCDMA Techniques & Technologies
    18. 18. Page 18Signal flowInterleavingSourcecodingConvolution&InterleavingScrambling Spreading ModulationRFtransmissionSourcedecodingdeinterleavingDecovolution&DeinterleavingUnscrambling De-spreading Demodulation RF receivingCDMA Techniques & Technologies
    19. 19. Page 19Common Technical Terms Bit, Symbol, Chip: A bit is the input data which contain information A symbol is the output of the convolution, encoder, and the blockinterleaving A chip is the output of spreading Processing Gain: Processing gain is the ratio of chip rate to the bit rate. The processing gain in IS-95 system is 128, about 21dB. Forward direction: Information path from base station to mobile station Reverse direction: Information path from mobile station to base stationCDMA Techniques & Technologies
    20. 20. Page 20In a typical duplex call, the duty ratio is less than 35%. To achievebetter capacity and low power consumption, base station reducesits transmission power.Source Coding Vocoder:8K QCELP13K QCELPEVRC CharacteristicsSupport voice activityCDMA Techniques & Technologies
    21. 21. Page 21Channel CodingConvolution code or TURBO code is used in channel encodingConstraint length=shift register number+1.Encoding efficiency= (total input bits / total output symbols)convolution encoderInput(bits)Output (symbols)CDMA Techniques & Technologies
    22. 22. Page 22Turbo CodeTurbo code is used during the transmission of large data packet. Characteristics of the Turbo code: The input information is encoded twice and the two output codes canexchange information with each other during decoding. The symbol is protected not only by the neighborhood check bits, but alsoby the separate Check Bits.The performance of a Turbo code is superior to that of a convolution code.CDMA Techniques & Technologies
    23. 23. Page 23InterleavingThe direction of the data stream1 2 873 64 51 2 873 64 51 2 873 64 51 2 873 64 51 2 873 64 51 2 873 64 51 2 873 64 51 2 873 64 51 2 873 64 51 2 873 64 51 1 111 11 12 22227 7 777 77 76 6 666 66 63 3 333 33 34 4 444 44 41 2 873 64 51 2 873 64 55 5 555 55 58 8 888 88 8interleavingCDMA Techniques & Technologies2 2 2
    24. 24. Page 24Out0 0 11 1 0Scrambling (M) sequence Two points are important here: Maximum number of shift register (N) Mask The period of out put sequence is 2N-1 bits Only sequence offset is change when the mask is changed PN stands for Pseudorandom Noise sequenceCDMA Techniques & Technologies
    25. 25. Page 25Long Code The long code is a PN sequence with period of 242-1chips The functions of a long code: Scramble the forward CDMA channel Control the insertion of power control bit Spread the information on the reverse CDMA channel to identify themobile stationsCDMA Techniques & Technologies
    26. 26. Page 26PNaPNcPNbShort CodeCDMA Techniques & Technologies Short code is a PN sequence with period of 215chips Sequence with different time offset is used to distinguish differentsectorsMinimum PN sequence offset used is 64 chips, that is, 512 PNoffsets are available to identify the CDMA sectors (215/64=512).
    27. 27. Page 27Walsh CodeW2n=Wn WnWn WnW1=0W2=0 00 1W4 =0 00 10 00 10 00 1Walsh code64-order Walsh function is used as a spreading function andeach Walsh code is orthogonal to other.Walsh Code is one kind of orthogonal code.A Walsh can be presented by Wimwhere ith(row) is theposition and m is the order. For example, W24means 0101code in W4 matrixCDMA Techniques & Technologies1 11 0
    28. 28. Page 28 In forward direction, each symbol is spread with Walsh code Walsh code is used to distinguish the user in forward link For IS95A/B, in the reverse, every 6 symbols correspond to one Walsh code.For example, if the symbol input is 110011,the output after spreading is W5164(110011=51). For CDMA2000, in the reverse, Walsh function is used to define the type ofchannel (RC 3-9)Walsh CodeCDMA Techniques & Technologies
    29. 29. Page 29Variable Walsh codes64481632129600 19200 38400 76800 153600 307200 614400Data rate -bps-W01 =0W02=00W12=01W04=0000W24=0011W14=0101W34=0110W08=00000000W48=00001111W28=00110011W68=00111100W18=01010101W58=01011010W38=01100110W78=01101001( W016,W816)( W416,W1216)( W216,W1416)( W616,W1416)( W116,W916)( W516,W1316)( W316,W1116)( W716,W1516)The different Walsh codescorresponding to different data ratesCDMA Techniques & Technologies
    30. 30. Page 30Modulation-QPSKIQI channel PN sequence1.2288McpsQ channel PN sequence1.2288McpsBaseband filterBaseband filterCos(2pfct)Sin(2pfct)I(t)Q(t)s(t)A1.2288Mcps: the PN chip rate of the system.After being spread, all the forward channels in the same carrier aremodulated by means of QPSK(OQPSK in the reverse), convertedinto simulation signals and transmitted after clustering.CDMA Techniques & Technologies
    31. 31. Page 31Power ControlHandoffDiversity and RAKECDMA Techniques & Technologies
    32. 32. Page 32PowerControlReverse power controlOpen loop power controlClosed loop power control− Inner loop power control: 800 Hz− Outer loop power controlForward power controlMessage transmission mode:− threshold transmission− periodic transmissionClosed loop power control.CDMA Techniques & Technologies
    33. 33. Page 33Reverse Open Loop PowerControl• The transmission power required by the mobile station is determined bythe following factors: Distance from the base station Load of the cell Circumstance of the code channels• The transmission power of the mobile station is relative to its receivedpower.BTSMobileReverse Open LoopPower ControlBTSBTSTransmittingPowerCDMA Techniques & Technologies
    34. 34. Page 34Reverse Closed Loop PowerControlBTSPower Control BitEb/Nt Value FER ValueInner Loop Power ControlOuter Loop Power ControlChange in Eb/Nt ValueCDMA Techniques & TechnologiesBSCBTS
    35. 35. Page 35Forward PowerControl MS measures the frame quality and informs the base station to theresult i.e. whether it is in the threshold or periodical mode. Base stationdetermines whether to change the forward transmitting power or not. In IS-95 system, the forward power control is slow but in CDMA2000system it is fast.CDMA Techniques & TechnologiesMessage Transmission Mode
    36. 36. Page 36Forward Closed Loop PowerControl Compared with IS-95 system, CDMA2000 the forward quickpower control is fast.Power Control BitEb/Nt ValueCDMA Techniques & TechnologiesBTS
    37. 37. Page 37HandoffSoft handoffIt is a process of establishing a link with a target sector beforebreaking the link with the serving sectorSofter handoffLike the soft handoff, but the handoff is occurred between multi-sectors in the same base stationHard handoffHard handoff occurs when the two sectors are not synchronizedor are not on the same frequency. Interruption in voice or datacommunication occurs but this interruption does not effect theuser communicationCDMA Techniques & Technologies
    38. 38. Page 38Soft/SofterHandoff• Multi-path combination in the BSC during soft handoff• Multi-path combination in the BTS during softer handoffsCombine all thepower from eachsectorPower received froma single sectorCDMA Techniques & Technologies
    39. 39. Page 39Pilot SetActiveSetCandidateSetNeighborSetRemainingSetThe pilot set, corresponding to the basestation being connectedThe pilot set, not in the active set butpotential to be demodulatedThe pilot set, not included in the active set orthe candidate set but being possible to beadded in the candidate setOther pilot setsthe set of the pilots having same frequency but different PN sequence offsetCDMA Techniques & Technologies
    40. 40. Page 40T_ADD,T_DROP,T_TDROPTimeEc/IoSectorA SectorBGuard Time(T-TDROP)Add Threshold(T_ADD)DropThreshold(T_DROP)Soft Handoff RegionT_ADD, T_DROP and T_TDROP affect the percentage of MS in handoff.T_ADD & T_DROP is the standards used to add or drop a pilot.T_DROP is a timer.CDMA Techniques & Technologies
    41. 41. Page 41Comparison Thresholdt0 t1 t2Pilot P1Pilot P2Pilot P0T_COMP×0.5dBT_ADDPilot strengthP0-Strengh of Pilot P0 in Candidate Set.P1,P2-Stength of Pilot P1,P2 in Active Set.t0-Pilot strength Measurement Message Sent, P0>T_ADDt1-Pilot strength Measurement Message Sent, P0>P1+T_COMP*0.5dBt2 -Pilot strength Measurement Message Sent, P0>P2+T_COMP*0.5dBCDMA Techniques & Technologies
    42. 42. Page 42Transition Between Pilot SetsT_ADDT_DROPPilot 1PilotstrengthPilot 2T_TDROPNeighborSetCandidateSetActiveSetNeighborSetTIME1 2 3 4 5 6CDMA Techniques & Technologies
    43. 43. Page 43Transmit Diversity Time diversity Block interleaving, error-correction Frequency diversity The CDMA signal energy is distributed on the whole 1.23MHZbandwidth. Space diversity The introduction of twin receive antennas . The RAKE receivers of the mobile station and the base station cancombine the signals of different time delay. During a handoff, the mobile station contacts multiple base stationsand searches for the strongest frameCDMA Techniques & Technologies
    44. 44. Page 44Transmission Diversity The forward transmission diversity types in CDMA2000 1X are TD (Transmit Diversity)− OTD (Orthogonal Transmit Diversity)▪ The data stream is divided into two parts, which will bespread by the orthogonal code sequence, andtransmitted by two antennas.− STS (Space Time Spreading)▪ All the forward code channels are transmitted by themulti-antennas.▪ Spread with the quasi-orthogonal code Non-TDCDMA Techniques & Technologies
    45. 45. Page 45Transmission DiversityThe Transmission Diversity Technology enhances the receive performance of MS.TransmissiondiversityprocessingData stream 1Data stream 2Data stream Restoring data streamPath 1Path 2Antenna 2Antenna 1CDMA Techniques & Technologies
    46. 46. Page 46The Principle of RAKE ReceiverRAKE antennas help to overcome on the multi-path fading and enhancethe receive performance of the systemReceive setCorrelator 1Correlator 2Correlator 3Searcher correlatorCalculate thetime delay andsignal strengthCombiner The combinedsignaltts(t) s(t)CDMA Techniques & Technologies
    47. 47. Page 47Course ContentsChapter 1 IntroductionChapter 2 CDMA Techniques & TechnologiesChapter 3 CDMA Air interfaceChapter 4 CDMA Number Planning
    48. 48. Page 48Physical Channel in IS-95AForward channel Forward Pilot Channel Forward Sync Channel Forward Paging Channel Forward Traffic Channel (including power control sub-channel)Reverse channel Access Channel Reverse Traffic ChannelCDMA Air Interface
    49. 49. Page 49Pilot channel(all-zeros)W064Pilot ChannelA pilot channel: Assist mobile station to be connected with CDMA network Handles multi-path searching Provide the phase reference for coherent demodulation and help the mobile stationestimate the transmission power The mobile station measures and compares the pilot channel powers from the basestations during the handoffForward pilot channel is spread over W0 and modulated with short code directlyBTS transmits the pilot channel continuouslyCDMA Air Interface
    50. 50. Page 50ToQPSKcoder2.4kbps 4.8kbps 4.8kbpsCodesymbolRepetitivecodesymbol1.2kbpsConvolutionencoderr=1/2,K=9symbolrepetitionBlockinterleavingSync Ch bitsW3264Sync Channel The sync channel is used by the mobile station to synchronize with the network.W32 is used to spread Sync Channel. The synchronization message includes:− Pilot PN sequence offset: PILOT_PN− System time: SYS_TIME− Long code state: LC_STATE− Paging channel rate: P_RAT Here note that, sync channel rate is 1200bpsCDMA Air Interface
    51. 51. Page 51ToQPSKcoderPagingchannel bitsPaging channel addressmaskLongcode PNgeneratordecimator1.2288McpsPaging Channel The paging channel transmits:− System parameters message− Access parameters− Neighbors list− CDMA channels list message The paging channel accomplishes:− Paging to MS− Assign traffic channel to MS The frame length of a paging channel is 20ms W1~W7 are spared for the Paging Channels spreadingCDMA Air Interface19.2/9.6Kbps 19.2kbps19.2kbpsCodesymbol9.6/4.8 kbpsConvolutionencoderr=1/2,K=9SymbolrepetitionBlockinterleaving19.2kbpsRepetitivecodesymbolW164
    52. 52. Page 52Forward Traffic ChannelCDMA Air InterfaceI Ch PN sequence (1.2288 Mcps)PN 1.2288 McpsRepetitivesymbol19.2kbps8.6kbps9.6kbps4.8kbps2.4kbps1.2kbpsAdd framequality indicatorbits(12,10,8,6)Add 8encoded tailbitsConvolutionencoderr=1/2,K=9SymbolrepetitionForward trafficchannal(172/80/40or16bits/frame)Blockinterleaver19.2kbpsMUXLong codegeneratorPower control bitsQ Ch PN sequence (1.2288 Mcps)BasebandfilterI(t)Q(t)decimator+∑QPSK Modulation4.0kbps2.0kbps0.8kbps19.2ksybps9.6ksybps4.8ksybps2.4ksybpsSin(2pfct)Cos(2pfct)is used to transmit data and signaling information.Walsh codedecimator++Basebandfilter++
    53. 53. Page 53Reverse Access Channelused by MS to initiate communication or respond to Paging ChannelCDMA Air Interface4.8 kbps(307.2kbps)PN chips1.2288 McpsOrthogonal spreadingRepetitivesymbol8.8 kbpsCodesymbol14.4 kbps4.4 kbps 4.8 kbpsAdd 8encoder tailbitsConvolutionencoderr=1/3,K=9SymbolrepetitionAccesschannel(80bits/frame)Blockinterleaving28.8 kbpsData burstrandomizerLong codePNgeneratorFrame rateLong code maskRepetitivesymbolWalsh codeI Ch PN sequence (1.2288 Mcps)BasebandfilterI(t)Q(t)∑QPSK ModulationSin(2pfct)Cos(2pfct)++Basebandfilter++Q Ch PN sequence (1.2288 Mcps)1/2 PN chips Delayedtime=406.9ns
    54. 54. Page 54Reverse Traffic Channel CDMA Air Interfaceused to transmit data and signaling information8.6kbps9.6kbps4.8kbps2.4kbps1.2kbpsAdd framequality indicatorbits(12,10,8,6)Add 8encoded tailbitsconvolutionencoderr=1/3,K=9SymbolrepetitionReverse trafficchannel(172/80/40 or16bits/frame)Blockinterleaver4.0kbps2.0kbps0.8kbps28.8Ksybps14.4Ksybps7.2Ksybps3.6Ksybps4.8 kbps(307.2kbps)PN chips1.2288 McpsOrthogonal spreadingData burstrandomizerLong codePNgeneratorFrame rateLong code maskWalsh codeI Ch PN sequence (1.2288 Mcps)BasebandfilterI(t)Q(t)∑QPSK ModulationSin(2pfct)Cos(2pfct)++Basebandfilter++Q Ch PN sequence (1.2288 Mcps)1/2 PN chips Delayedtime=406.9ns
    55. 55. Page 55Initialization of the MS Synchronous Channel message contains the LC_STATE, SYS_TIME,P_RAT, and synchronizes with the system.CDMA Air InterfaceBTSPilot channelSynchronous channelPaging channelAccess channel
    56. 56. Page 56CDMA2000 Forward ChannelForward CDMA2000 channelF-CACH F-CPCCH F-PICH F-CCCHF-DCCH F-FCHF-PC F-SCCH F-SCHF-PICH F-TDPICH F-APICH F-ATDPICHF-SYNCH F-TCH F-BCH F-PCH F-QPCHsubchannel (RC1~2) (RC3~9)Note: Only the channels with black color are being implemented inHuawei equipment. The function of F-PICH, F-SYNCH, F-FCH, F-PC, F-SCCH, F-PCH are the same as those of IS95. We will only discuss F-SCH,F-QPCH F-DCCH in the following slides.CDMA Air Interface
    57. 57. Page 57Forward channelThese channels are newlydefined in CDMA2000 system.CDMA physical channels are classified in common channels and dedicated channels:Common physical channels:Forward Pilot Channel(F-PICH)Forward Synchronous Channel(F-SYNC)Forward Paging Channel(F-PCH)Forward Broadcast Control Channel(F-BCCH)Forward Quick Paging Channel(F-QPCH){not compatible wid is95}Forward Common Power Control Channel(F-CPCCH)Forward Common Assignment Channel(F-CACH)Forward Common Control Channel(F-CCCH)These channels are compatiblewith IS-95 systemDedicated physical channel:Forward Dedicated Control Channel(F-DCCH)Forward Fundamental Channel(F-FCH)Forward Supplemental Channel(F-SCH)These channels are used to establish the connection between a base station and aspecific mobile station.The CDMA2000 system adopts multiple data rates and the different combinations ofchannels can achieve a performance superior to that in IS-95 system.CDMA Air Interface
    58. 58. Page 58F-QPCH It transmits OOK-modulated signal which can be demodulated by MSsimply and rapidly. The channel adopts 80ms as a QPCH timeslot. Each timeslot is divided intopaging indicators, configuration change indicators and broadcastindicators, all of which are utilized to inform the MS whether to receivepaging message, broadcast message or system parameters in the next F-PCH. Rapid and simple demodulation. MS no need to monitor F-PCH for longtime, so the standby time is prolonged.CDMA Air Interface
    59. 59. Page 59F-SCH F-SCH is typically used for high speed dataapplications, while F-FCH is used for common voiceand low speed data application. When a data call is established, firstly, F-FCH will beallocated to the user. If the speed of data for userexceeds 9.6kbps, F-SCH will be allocated.CDMA Air Interface
    60. 60. Page 60F-DCCH It is used for the transmission of specific user signalinginformation during a call. Each forward traffic channel may contain one F-DCCH. Support 5ms frame. Support discontinuous transmission.CDMA Air Interface
    61. 61. Page 61Forward Radio Configuration (RC)Radio Configuration(RC):A set of Forward Traffic channel and Reverse Traffic Channel transmissionformats that are characterized by physical parameters such as data rates,modulation characteristics, and spreading rate.Spreading Rate: Equivalent to chips rate, e.g., 1.2288Mcps.RadioConfigurationSpreadingRateMax Data Rate*(kbps)Effective FECCode RateOTDAllowedFEC Encoding Modulation1** 1 9.6 1/2 No Conv. BPSK2** 1 14.4 3/4 No Conv BPSK3 1 153.6 1/4 Yes Conv and Turbo QPSK4 1 307.2 1/2 Yes Conv and Turbo QPSK5 1 230.4 3/8 Yes Conv and Turbo QPSK6 3 307.2 1/6 Yes Conv and Turbo QPSK7 3 614.4 1/3 Yes Conv and Turbo QPSK8 3 460.8 1/4 or 1/3 Yes Conv and Turbo QPSK9 3 1036.8 1/2or 1/3 Yes Conv and Turbo QPSKCDMA Air Interface
    62. 62. Page 62Reverse ChannelReverse CDMA2000 channelR-ACHR-TCHoperation(RC1~2)R-EACHoperationR-CCCHoperationR-SCCHR-FCHR-TCHoperation(RC3~6)R-EACHR-PICHR-CCCHR-PICHR-DCCHR-PICH0~7 0~1R-SCHR-FCH0~20~1subchannelR-PCOnly the channels in dark color are used in Huaweiequipment. The function of R-ACH,R-FCH,R-SCCHare the same as those in IS95. We will only discussR-PICH,R-SCH in the following slides.CDMA Air Interface
    63. 63. Page 63Types of Reverse Channel Reverse channel includes reverse common channel and reversededicated channel. Reverse common channel: Reverse Access Channel(R-ACH) Reverse Enhanced Access Channel(R-EACH) Reverse Common Control Channel(R-CCCH) Reverse Dedicated Channel Reverse Pilot Channel(R-PICH) Reverse Dedicated Control Channel(R-DCCH) Reverse Fundamental Channel(R-FCH) Reverse Supplemental Channel(R-SCH) Reverse Supplemental Code Channel (R-SCCH)CDMA Air Interface
    64. 64. Page 64MUX APilot( all 0s)Power Control BitN is the Spreading Rate numberPilot PowerControlPower Control Group= 1536 NPN Chips384 NPN ChipsReverse Pilot ChannelR-PICH The Function of Reverse Pilot Channel Initialization Tracing Reverse Coherent Demodulation Power Control Measurement Base station enhances the receivedperformance and increases the capacity bymeans of coherent demodulation of the ReversePilot Channel.CDMA Air Interface
    65. 65. Page 65Reverse Channels Fundamental Channel: Fundamental Channel is used for the transmission of user informationto the base station during a call, and can be used to transmit defaultedvoice services as an independent Traffic Channel. Dedicated Control Channel The Dedicated Control Channel is used for the transmission of userand signaling information to a base station during a call. Supplemental Channel/Supplemental Code Channel These channels are used for the transmission of user information,mainly data services, to the MS. The Reverse Traffic Channel containsup to two supplemental channels and up to seven supplemental codechannels.CDMA Air Interface
    66. 66. Page 66Reverse Radio Configuration (RC)RC: Radio ConfigurationRC1~RC2:IS-95A/BRC3~RC4:CDMA2000 1XRC5~RC6: CDMA2000 3xRadioConfigurationSpreadingRateMax Data Rate*(kbps)Effective FECCode RateOTDAllowedFEC Encoding Modulation1** 1 9.6 1/3 No Conv 64-ary ortho2** 1 14.4 1/2 No Conv 64-ary ortho3 1 153.6 1/4 Yes Conv or Turbo BPSK(307.2) (1/2)4 1 230.4 3.8 Yes Conv or Turbo BPSK5 3 153.6 1/4 Yes Conv or Turbo BPSK(614.4) (1/3)6 3 460.8 1/4 Yes Conv or Turbo BPSK(1036.8) (1/2)** Same as IS95CDMA Air Interface
    67. 67. Page 67RC 1RC 2RC 3RC 4RC 5RC 1RC 2RC 3RC 4RC 5RC 3RC 4RC 4RC 3F-FCHRCsR-DCCH/SCHRCsF-DCCH/SCHRCsR-FCHRCsRC Combination Regulation RC1 and RC2 corresponds respectively torate set 1 and rate set 2 in IS- 95A/B system. CDMA2000 Forward RC: RC1~RC5Reverse RC: RC1~RC4 Rules: Forward RC1, Reverse RC1 Forward RC2, Reverse RC2 Forward RC3 or RC4,Reverse RC3 Forward RC5, Reverse RC4CDMA Air Interface
    68. 68. Page 68Course ContentsChapter 1 IntroductionChapter 2 CDMA Techniques & TechnologiesChapter 3 CDMA Air InterfaceChapter 4 CDMA Number Planning
    69. 69. Page 69Definition of Coverage AreasLocation areaMSC areaPLMN areaService areaSectorareaCDMA Number PlanningCell area
    70. 70. Page 70Parameters InvolvedIn a CDMA system, the following parameters are defined toidentify a user and his location:MIN/IMSI MDN ESN TLDN SID/NID LAI GCI SIN SSNCDMA Number Planning
    71. 71. Page 71MIN/IMSIMobile subscriber identity/international mobile subscriber identityFor example, 0907550001/460030907550001Not more than 15 digits3 digits 2 digitsIMSIMCC MNC MSINNMSICDMA Number Planning
    72. 72. Page 72MDNCC + MAC + H 0H1H 2H 3 + ABCDInternational mobile subscriber DNNational valid mobile subscriber numberMobile directory numberFor example, 8613307550001CDMA Number Planning
    73. 73. Page 73ESNA unique Electronic Serial Number (ESN) is used to identify singleMS. An ESN includes 32 bits and has the following structure:31......24 23......18 17......0 bitManufacturer’s number retained equipment SNFor example, FD 03 78 0A (the 10th Motorola 378 mobile phone)The equipment serial number is allocated by a manufacturer.CDMA Number Planning
    74. 74. Page 74TLDN+CC MAC H0H 1H2 ABC+ ++44Temporary local directory numberFor example, 8613344755001CDMA Number Planning
    75. 75. Page 75SID/NIDMSCID (Exchange Identity)= System Identity (SID) + Exchange number (SWIN)is used to represent a certain set of equipment in anNSS network. For example,Unicom CDMA Shenzhen MSC is labeled as 3755+01CDMA Number Planning
    76. 76. Page 76Location Area Identity (LAI) PAGING message is broadcast within a local area, the size of which depends ontraffic, paging bearer capability, signaling flow , etc. Format: MCC+MNC+LAC MCC: Mobile Country Code, 3 digits. For example, China is 460. MNC: Mobile Network Code, 2 digits. For example, the MNC ofUnicom is 03. LAC: Location Area Code, a 2-byte-long hexadecimal BCD code.0000 cannot be used with FFFE. For example, 460030100CDMA Number Planning
    77. 77. Page 77Global Cell Identity (GCI) The unique ID of a cell in PLMN Format: LAI+CI CI: Cell Identity, a 2-byte-long hexadecimal BCD code, pre definedby the engineering department. The first 3 digits and the last digitrepresent the base station number and the sector numberrespectively. For an omni-directional site, the last digit of CI is 0. For example, 4600301001230 shows base station number 123contains an omni-directional siteCDMA Number Planning
    78. 78. Page 78Sender Identification Number(SIN)MSC numberThe MSC number stipulated by Unicom is 460 + 03 + 09 + H0H1H2H3 +1000.HLR numberThe HLR number stipulated by Unicom is 460 + 03 + 09 + H0H1H2H3 +0000.SMC numberThe SMC number stipulated by Unicom is 460 + 03 + 09 + H0H1H2H3 +2000.SCP numberThe SCP number stipulated by Unicom is 460 + 03 + 09 + H0H1H2H3 +3000.CDMA Number Planning
    79. 79. Page 79Sub-System Number(SSN) SSN of MSC: 8 SSN of VLR: 7 SSN of HLR: 6 SSN of AC: 10 SSN of SMC: EE SSN of SCP: EF SSN of A interface: FE/FC SSN of SCCP management: 1CDMA Number Planning
    80. 80. Page 80Review Chips rate: 1.2288Mcps IS-95A/B is a subset, RC1/RC2 Apply the coherent demodulation to the reverse pilot channel Forward transmit diversity: OTD and STS Forward quick power control at 800HZ rate Improve the standby time by introducing the quick paging channel. Variable frames: 5ms, 20ms, 40ms and 80ms Introduce TURBO code into channel encoding The maximum rate of a physical layer is up to 307.2KCDMA Technology
    81. 81. Page 81Why CDMA2000? Increase the system capacity Forward quick power control Forward transmit diversity: OTD,STS Coherent modulation applied on the pilot channel.(about3dB) The introduction to Turbo code The stronger ability to resist interference The improved error-correcting encoding (applying Turbocode in medium/high rate data transmission)
    82. 82. Page 82Why CDMA2000? Support high rate SCH, with the maximum rate of a singlechannel being up to 307.2kbps. Improve the standby time Use the quick paging channel Forward compatibility Radio-frequency part Baseband part, such as RC
    83. 83. Page 83Summary Brief Development History of Mobile Communication Analog--digital--code division Objectives of 3G and comparison of 3 systems Technical features of CDMA Key technologies: power control, soft handoff,RAKE receiver andcell breath Other technologies: source coding, channel coding, interleaving,scrambling, spreading and modulation Channel structure: pilot, synchronization, paging, access andservice Technical features of CDMA2000 1X Walsh and Turbo codes
    84. 84. Page 84Questions What power control modes are there in CDMA2000 systemand how are they implemented? Describe the soft handoff process? Describe the process and functions of cell breath? Describe the implementation process of service channels(forward and reverse)? Describe the technical features of CDMA2000? Describe the initialization process of a mobile phone? What are the functions of a long code, short code and Walshcode in CDMA system?

    ×