Technology - Mobile 5 - 3G Technologies, Spreading & Scrambling

Synopsis

We discuss 3G’s background and spectrum allocations, DoCoMo’s FOMA WCDMA system, the Time Division Duplex WCDMA technologies TD-CDMA and TD-SCDMA - the latter being developed by China. We also provide a tutorial on frequency spreading and scrambling, which are the two key techniques underlying CDMA, CDMA2000 and the WCDMA 3G technologies.

Table of Contents

• 1. Synopsis
  
• 2. 3G background
  
  • 2.1 No single global 3G standard
    
• 3. 3G Technologies
  
  • 3.1 DoCoMo FOMA WCDMA
    
    • 3.1.1 DoCoMo’s 4G plans
      
  • 3.2 TD-CDMA and TD-SCDMA
    
    • 3.2.1 Timing disadvantages of Time Division Duplexing (TDD)
      
    • 3.2.2 Inter-cell interference
      
    • 3.2.3 TD-SCDMA in China
      
    • 3.2.4 TD-CDMA for broadcasting
      
  • 3.3 3GPP2 CDMA2000
    
  • 3.4 IMT-SC - GSM EDGE
    
  • 3.5 IMT-FT - DECT
    
  • 3.6 UWC-136
    
  • 3.7 3G Spectrum
    
• 4. Spreading and Scrambling
  
  • 4.1 The spreading code
    
    • 4.1.1 Rejecting narrowband interference
      
    • 4.1.2 Multipath reception
      
    • 4.1.3 Rejecting other data channels
      
    • 4.1.4 Orthogonal spreading patterns
      
  • 4.2 Pseudo-noise and non-orthoganality
    
    • 4.2.1 Separating signals to and from handsets
      
    • 4.2.2 Variable length spreading codes
      
  • 4.3 The scrambling code
    
    • 4.3.1 UMTS WCDMA base-station ID
      
• 5. Related reports