1 / 11

WCDMA Introduction Spreading Code

WCDMA Introduction Spreading Code. Chia-Chi Yu 2004.8.13. Outline. WCDMA two layer Spreading Channelization code – OVSF code How to generate OVSF code? Scrambling code – Gold sequence Conclusions. Spreading. Two layer spreading. Define DL and UL.

waite
Download Presentation

WCDMA Introduction Spreading Code

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. WCDMA IntroductionSpreading Code Chia-Chi Yu 2004.8.13

  2. Outline • WCDMA two layer Spreading • Channelization code – OVSF code • How to generate OVSF code? • Scrambling code – Gold sequence • Conclusions

  3. Spreading • Two layer spreading

  4. Define DL and UL • DL(downlink): Node B(BaseStation) to User Equipment(Mobile) • UL(uplink):UE to Node B

  5. Channelization Code • Usage◇Uplink: Separation of DPDCH and DPCCH from the same terminal◇Downlink: Separation of downlink connections to different users within one cell • Using OVSF code • Length◇Uplink: 4~256 chips same as SF ◇Downlink:4~512 chips same as SF

  6. OVSF code • Orthogonal Variable Spreading Factor→The Spreading Factor can be changed (e.g.,for variable bit rate service) • Orthogonality preserved across the different symbol rates

  7. OVSF code generation method

  8. Scrambling code • Usage◇Uplink: Separation of UE(Mobile) ◇Downlink: Separation of Base Station(cell) • Since WCDMA uses different scrambling codes to separate user from cells, it is not necessary to be synchronous between BS • Gold Sequence

  9. Scrambling code generator

  10. Scrambling code(DL) • Length: 38400 chips(both UL and DL) • Use a 10msec radio frame of a 218-1 shortened Gold sequence • Total number of codes : 262,143 • Use only 8,192 codes→ Broken into 512 sets of codes • Each set has 1 primary code with 15 secodary codes • Primary codes are further broken into 64 code groups, each with 8 primary codes

  11. Conclusions • Limited OVSF codes must be reused in every cell→Interference if two cells use the same code→Scrambling codes provide solutions • Asynchronous BS

More Related