Method for quasi-synchronous code division multiple access based on synchronization clock by piloting

A method for quasi-synchronous code division multiple access (CDMA) based on a synchronization clock by piloting, comprising:

• adopting a mode of CDMA spread spectrum transmission to share power resources to transmit signals at multiple transmitting stations in open wireless channels;
• adopting an external pilot signal to provide the synchronization clock for CDMA signals transmitted by multiple terminal stations in the open wireless channels, wherein the external pilot signal comprises stable and continuous synchronization clock information and continuous reference timing information;
• eliminating path delay differences from the multiple terminal stations to a relay node or a receiving terminal station;
• making multi-channel CDMA signals received at the relay node or the receiving terminal station realize a clock synchronization and a phase alignment, so as to realize a quasi-synchronous reception of the multi-channel CDMA signals;
• receiving the external pilot signal to ensure that the multiple terminal stations in a system realize a clock quasi-synchronization based on an external clock and establish a time reference;
• transmitting a test frame to a receiving terminal station respectively at multiple transmitting terminal stations on a basis of realizing the clock quasi-synchronization by the external pilot signal;
• receiving a test response responded by the receiving terminal station;
• measuring a distance between each of the transmitting terminal stations and the receiving terminal station, if there is no relay node in the open wireless channels and the multiple terminal stations transmit the CDMA signals to the same terminal station;
• performing phase compensation for a distance difference of the multiple terminal stations transmitting the CDMA signals relative to corresponding receiving terminal stations to make transmitted multi-channel CDMA signals realize the phase alignment when reaching the corresponding receiving terminal stations;
• and
• realizing the clock synchronization and the phase alignment based on the external pilot signal by combining with the clock quasi-synchronization based on the external pilot signal, so as to ensure a quasi-synchronous combination of the transmitted multi-channel CDMA signals at the receiving terminal stations.

A method for quasi-synchronous code division multiple access (CDMA) based on a synchronization clock by piloting, comprising:

• adopting a mode of CDMA spread spectrum transmission to share power resources to transmit signals at multiple transmitting stations in open wireless channels;
• adopting an external pilot signal to provide the synchronization clock for CDMA signals transmitted by multiple terminal stations in the open wireless channels;
• eliminating path delay differences from the multiple terminal stations to a relay node or a receiving terminal station;
• making multi-channel CDMA signals received at the relay node or the receiving terminal station realize a clock synchronization and a phase alignment , so as to realize a quasi-synchronous reception of the multi-channel CDMA signals;
• maintaining the synchronization clock by continuously or intermittently receiving the external pilot signal after realizing a clock quasi-synchronization based on the external pilot signal;
• transmitting periodically a probe frame to the relay node or a receiving terminal station at the transmitting terminal stations due to a change of distances accumulated with time between the transmitting terminal stations and the relay node, or between the transmitting terminal stations and the receiving terminal station;
• and
• re-measuring the distance and resetting a phase to realize the phase alignment.