Cdma
- Use spread spectrum techniques.
- Every channel uses full frequency channel.
- Conversation are encoded with pseudo random digital signal.
- Better capacity for data and vioce.
- Common tech in 3g umts and wcdma.
- Also in gps.
- A spread spectrum technique spreads the bandwidth of the data uniformly for the same transmitted power.
- Code run at much higher speed than data.
- Data is bitwise xor with code.
- The separation of the signals is made by correlating the received signal with the locally generated code. If the signal matches User code then the correlation function will be high and the system can extract that signal. If the user's code has nothing in common with the signalthe correlation then zero (thus eliminating the signal); this is referred to as cross-correlation .
0 comments:
Post a Comment