Downloaded 28 times
Uploaded byAbidur Rahman
WCDMA
WCDMA (Wideband Code Division Multiple Access), also known as UMTS, is a 3G cellular technology that uses CDMA with a bandwidth of 5MHz. It offers greater spectral efficiency and bandwidth than previous standards. Key features include high spectral efficiency through frequency multiplexing, soft capacity control through variable transmission power, and compatibility with GSM networks. WCDMA differs from earlier CDMA standards by using a wider bandwidth and supporting both circuit-switched and packet-switched networks for data and voice.
WCDMA
- 1.
- 2. Hello! I AM ABIDURRAHMAN Student of 4th year 1st term, Department of E.E.E. Khulna University of Engineering & Technology Contact: abidurrahman.425@gmail.com
- 3. Contents ◦ Features ofWCDMA. ◦ Concept of WCDMA. ◦ How it differs from CDMA. ◦ Comparison between GSM & WCDMA.
- 4. WCDMA Wideband Code DivisionMultiple Access
- 5. Wideband Code DivisionMultiple Access , also known as Universal Mobile Telecommunication System (UMTS) , is a specific air interface used by 3rd Generation mobile cellular system that uses CDMA technique and modulated at 5MHz. UMTS was developed & maintained by 3GPP (3rd Generation Partnership Project). UMTS uses wideband code division multiple access (W- CDMA) radio access technology to offer greater spectral efficiency and bandwidth to mobile network operators.
- 6. Features • High SpectralEfficiency -Frequency multiplex coefficient is 1. • Soft capacity -Quality -Coverage -Interference • Self-interference system -A UE transmission power is interference for another UE. • Wideband system • Compatible with GSM-MAP core network • Support open loop and closed loop transmit diversity mode • Support different fast power control algorithms and open loop, out loop power control
- 7. Technical Features ofWCDMA- FDD
- 8.
- 9. Starting from GSMtechnique (the Room Concept) • 200KHz for each channel (room)--- FDM • Each channel (room) is separated from one another through Guard-band (walls) • Each channel (room) is used by 8 users --- TDM Let’s Consider, BW= 11MHz i.e. the size of House (here)
- 10. Starting from GSMtechnique (the Room Concept) Now select just one room (red in this case)
- 11. Explaining GSM 200KHZ channel InnerView of each room 8 people sharing the same room but in different times i.e. TDM
- 12. Explaining GSM • Bothare talking with the Base Station at the same time but in different frequencies. • Enough spacing between two rooms. • So person in one room shouldn’t hear person in another room i.e. less interference. BUT WAIT… WALLS HAVE EAR… • Talk at a low voice ( i.e. transmit less power). • POWER CONTROL • Power can be controlled in every 480ms.
- 13. Explaining WCDMA Once againroom concept…
- 14. Explaining WCDMA • Inthis case, every user in every room transmits at same frequency i.e. 5MHz. • Each room may have more than one (usually a lot) users.
- 15. Explaining WCDMA 5 MHz5 MHz 5 MHz 5 MHz 5 MHz 5 MHz 5 MHz At Same Frequency At Same Time
- 16.
- 17. Explaining WCDMA 5 MHz5 MHz 5 MHz 5 MHz 5 MHz 5 MHz 5 MHz Different Languages
- 18. Explaining WCDMA • Differentlanguages means different codes. • Different codes within this same channel is called Channel Codes. • Also known as Walsh Code or Spreading Code. • These Channel Codes are Orthogonal in nature. Here Orthogonal means the codes within a channel don’t interfere with each other.
- 19. Explaining WCDMA 5 MHz5 MHz 5 MHz 5 MHz 5 MHz 5 MHz 5 MHz Different Languages SHOUTING LOUD
- 20. Explaining WCDMA • PowerControl i.e. changing the transmission power for both Up-Link and Down-Link. • Goal is to transmit minimum possible power. • In WCDMA power control is done 1500 times per seconds which requires really first switching.
- 21. Explaining WCDMA What ifwe assign same codes to neighboring Channels !!!!! Of course they might interfere with each other. So Scrambling Codes are used to reduce the inter-base- station interference.
- 22. Basic Diagram ofthe WCDMA System Source coding Channel coding and interleaving Spreading Scrambling Modulation RF transmission R a di o li n k Source Decoding DemodulationDescramblingDe-spreading Channel decoding and de- interleaving RF reception
- 23. Comparision between WCDMA& CDMA • The basic difference between the CDMA and WCDMA is bandwidth, CDMA uses 1.25MHz frequency bandwidth while WCDMA uses 5MHz bandwidth. • So, CDMA is a modulation technique and WCDMA is specific standards that uses it. • CDMA is 2g telecommunication standard and provide very less data rates compared to WCDMA which is third generation technology. • CDMA being 2g standard provide mainly circuit switched services while WCDMA being used in UMTS system is used in both circuit switched and packet switched networks.
- 24. A Comparision betweenWCDMA & GSM
- 25. Hopefully it washelpful to you all.
- 26.