How to Reverse Access Channel Work in CDMA?
Reverse Access Channel used by MS Initiate Communication or Respond to Paging Channel.
- A reverse channel is first spread with WALSH to 307.2Kbps and then becomes 1.2288Mcps after long code modulation. The long code here not only spreads spectrum, but implements the function of channelization.
- “Data burst randomizer” means discarding repeated chips during the transmission according to a certain algorithm and implementing discontinuous transmission so as to reduce the transmission rate and increase the capacity of reverse channels.
- In QPSK reverse modulation, as opposed to the data modulated by I channel PN sequence, the data modulated by Q channel PN sequence has the delay of half a PN chip (406.901ns). Thus, the maximum phase change of four-phase modulation is 90 degrees instead of 180-degree mutation.