Signaling Channels -> carry user data

Key requirement for 3G: high-data rate.

The physical layer should be more efficient to do that.
In IS-95, the signaling information is carried by traffic(fundamental) channel.

In IS-2000, separate signaling channels are the option.

F-DCCH:
可以用來傳輸零星的SMS之類的Low-rate data 而不用浪費資源開一個CHANNEL
有兩種 20ms/5ms 的FRAME