“W-CDMA” PRESENTED BY-GYANENDRA PRASAD PANIGRAHI REGD.NO-0901304190 GUIDED BY- Mr. SHAKTI NARAYANA MISHRA DEPT.-ELECTRONICS AND COMMUNICATION ENGINEERINGGANDHI INSTITUTE OF TECHNOLOGY AND MANAGEMENT BHUBANESWAR
INTRODUCTION WCDMA stands for Wide Band Code Division Multiple Access. W-CDMA is a Third-Generation(3G) mobile wireless technology that promises much higher data speeds to mobile and portable wireless devices than commonly offered in todays market. It is specified by 3rd Generation Partnership Project (3GPP). It is the key technology for UMTS.
HISTORYQUALCOMM , the first company to succeed in developing a practical and cost effective CDMA implementation for consumer cell phones.The worlds first commercial W-CDMA service was launched by NTT DoCoMo in Japan.
DUPLEXING It means to allow the Subscriber to send simultaneously information to the base station while receiving information from the base station. It is of two types. (a) FDD (b) TDD In FDD , (1) Forward Band :- Traffic from base station to mobile (2) Reverse Band :- Traffic from mobile to base station
DUPLEXING(cont…) In FDD Duplexer is used. The frequency separation between each forward & reverse channel is constant through out the system. In TDD , Time is used to provide both a forward & reverse link. Each duplex channel has forward & reverse time slots. Duplexer is not required. It is effective when all the users are stationary.
MULTIPLE ACCESS TECHNIQUES These are used to allow many mobile users to share a finite amount of radio spectrum simultaneously. The sharing of spectrum is required to achieve high capacity by simultaneously allocating the available bandwidth (or) available amount of channels to multiple users. Multiple access techniques are of three types.1) FDMA2) TDMA3) CDMA
MULTIPLE ACCESSTECHNIQUES(cont…) In FDMA, It assigns individual channels to individual users. Each user is allocated a unique frequency band. In TDMA, It divides radio spectrum into time slots and in each slot only one user is allowed to either transmit or receive. In CDMA, It allows numerous signals to occupy a single Transmission channel, optimizing the use of available bandwidth. It employs analog-to-digital conversion & Spread Spectrum Technology. Each user has a unique code word. Unlike TDMA or FDMA CDMA has a soft capacity limit.
SPREAD SPECTRUM TECHNIQUE-I A kind of modulation system in which the modulated signal bandwidth is much greater than the message signal bandwidth. The spectral spreading is performed by a code that is independent of the message signal. Codes are fully orthogonal. It is of two types . 1) DS-SS 2) FH-SS
SPREAD SPECTRUM TECHNIQUE-II In DS-SS, it spreads the base band data by directly multiplying the base band data pulses with a pseudo- noise (PN) sequence. In FH-SS, frequency hopping means periodic change of transmission frequency. A frequency hopping signal may be regarded as a sequence of modulated data with time varying pseudo random carrier frequencies. The DS-Multiple Access is known as CDMA.
WCDMA APPLICATIONSFor the consumer Video streaming, TV broadcast Video calls, video clips – news, music, sports Enhanced gaming, chat, location services…For business High speed teleworking Sales force automation Video conferencing Real time financial information
CONCLUSION WCDMA has many advantages like much higher B.W (5 MHz),high chip rate(3.84Mcps),high data rate(up to 2 Mbps),enhanced security and so on… Thus it is the growing technology for mobile generations.
REFERENCES T.S.Rappaport “ Wireless Communications” Forouzan “Data Communication And Networking” http://www.google.com http://www.google.com/wikipedia