| 摘要 |
A subchannel within a CDMA signal is provided together with a system for receiving and decoding this subchannel. A message is transmitted over the subchannel by applying a sequence of phase rotations to the user data. A single subchannel message can be transmitted during each 1.25 ms segment of user data, resulting in a transmission rates of up to 800 messages per second over the subchannel. Each message corresponds to a fixed sequence of phases, called a phase codeword, used to rotate the user data each time that message is sent. When only two phase codewords are used, the effective data rate for the subchannel is 800 bits per second, but higher data rates may be achieved by increasing the number of codewords used by the subchannel. The subchannel may be decoded by correlating the user data with each of the possible phase codewords. |
