| 摘要 |
In a direct spread-spectrum communication system for transmitting and receiving signals multiplexed according to a data format having a simplex (not multiplexed) portion and a multiplexed portion, a transmission error ratio of ACK and NAK signals is decreased and the transmission method is changed according to the transmission path conditions, thus improving a throughput of the system. On receipt of the header information, station B synchronizes a spread-spectrum signals, reproduces the clock according to a bit-synchronization signal and accomplishes the automatic gain control (AGC) and synchronization of the data by synchronization-pattern. The station B looks for and recognizes information about the multiplexing number and aligns its circuit to the recognized multiplexing number. The station B then knows the length of the packet received, decodes the packet and performs cyclic redundancy checking (CRC) to judge whether data was correctly received or not. On the basis of the judgment result, the upper layer (6) determines which signal ACK or NAK to be sent to the station A. The signal ACK or NAK is sent to the station A in the simplex (not multiplexed) state with information about the multiplexing number being always 1. In this instance, the signals ACK and NAK transmitted in the simplex mode can have a considerably improved error rate as compared with that of the signals transmitted in a multiplexed state. Thus, the transmission error with signals ACK and NAK can be surely reduced by transmitting them in the simplex state. This decreases the probability of re-transmission of an unnecessary packet due to the incorrect receipt of the signal ACK at the station A. <IMAGE> |
