介绍CDMA和WCDMA.ppt

1、Introduce CDMA and WCDMA,Reference,CDMA及第三代移动通信系统( WCDMA系统的关键技术( WCDMA principles of wireless communications,Outline,The develop of mobile communication technology Principle of CDMA Multi-path interference WCDMA,The Develop of Mobile Communication Technology,The Basic Framework of 3G,Ability of tran

2、smission: To provide a wide range of business,3GPP and 3GPP2,3rd Generation Partnership Project,Principle of CDMA(1/3),Spread spectrum,Certain signal transmission of broadband data,The send,The receive,Bandwidth much larger than a signal bandwidth,High-speed pseudo-random,Carrier wavemodulation,Sign

3、al bandwidth,The spread spectrum,Original data,Principle of CDMA(2/3),PN: Is a regular periodic binary sequences. Long code Short code Different purposes: Forward channel: Long code scramble code, short code orthogonal modulation (identify base station) Reverse channel: Long code spread spectrum (id

4、entify user),Principle of CDMA(3/3),A: 0 0 0 1 1 0 1 1 A: (-1-1-1+1+1-1+1+1) B: 0 0 1 0 1 1 1 0 B: (-1-1+1-1+1+1+1-1) C: 0 1 0 1 1 1 0 0 C: (-1+1-1+1+1+1-1-1) D: 0 1 0 0 0 0 1 0 D: (-1+1-1-1-1-1+1-1) Three examples: 1 1 1 1 0 ,The Advantages of CDMA,Due to spread spectrum to expand spectra of signal

5、. Multiple access capability. Anti-interference ability to multi-path. Privacy. Anti-interference to Man-made ability. Anti-interference ability to narrow-band.,Compare Narrow-Band and Wide-Band,Essence of CDMA(1/3),A wireless is the method that resources statistical multiplex. Mobile communication

6、systems need to resolve the question how multiple users to share wireless media which is to solve the problem multiple access.,Essence of CDMA(2/3),CDMA is the system that is interference themselves-the system users there is the interference between each other. When the increase in the number of use

7、rs, the system performance should be to reduce.,Essence of CDMA(3/3),Multiple Access Technology Icon,Several Different Forms of CDMA,DSCDMA, FHCDMA, THCDMA,Key Technology of CDMA,Power control technology Receiver RAKE technology Soft-Switch technology,Technical of RAKE Receive,Signal channel is a mu

8、lti-path fade channel, technical of RAKE receive is the way that receive each of the signal separately to demodulate and then superimposed output reached to enhance reception.,Soft-Switch Technology,More soft-switch,CDMA Need to Resolve Issue,Due to CDMA users rely on the signature to distinguish, r

9、esolve the multi-path interference: RAKE physical layer technology to receive Multi-user detection Smart antennas,Multi-User Detection,CDMA take the other users interfere as noise. The best receiver is joint detection all the signals and deduct the other users interfere from expectant signal. MUD re

10、duce the interference of multi-path, enhance the capacity of the system. MUD can alleviate the problem of near-far effectively.,Principle of Smart Antennas(1/2),To reduce interference from the other direction, raising the direction of necessary signal reception sensitivity. Expand the range of cover

11、age of base stations, improve the quality of the signal transmission.,Principle of Smart Antennas(2/2),Smart antenna make use of space users in different locations to distinguish between different users. Bring in SDMA.,Smart Antenna Configuration of The area,The Advantages of Smart Antenna,For high-

12、speed users carry on beam track, play the spatial segregation and elimination disturbance. Increasing the system capacity. Increasing the range of coverage. To improve signal reception quality. To reduce their transmitting power.,WCDMA,It adopt MC FDD duplex mode and has a good compatibility and int

13、eroperability with the GSM network. WCDMA adopt the latest Asynchronous Transfer Mode(ATM),Micro-Cell Transfer Protocol.,FDD and TDD,Acronyms,GSM: Global System for Mobile Communications. CDMA: Code Division Multiple Access. WCDMA: Wideband Code Division Multiple Access. HSDPA: High Speed Downlink Packet Access. TDMA: Time Division Multiple Access. FDMA: Frequency Division Multiple Access. OFDM: Orthogonal Frequency Division Multiplexing RRM: Radio Resource Management. QoS: Quality of Service. U