| 摘要 |
PROBLEM TO BE SOLVED: To assign spread codes so that they will not be the same among terminals, and make a base station side easily know the codes by imposing spread modulation directly on an answer signal by using the code of a code information signal added to a call signal. SOLUTION: A central office 13 when converting its call request signal into a call signal sequence adds code information signals to respective call signals and sends them to base stations 14-1 to 14-n. A base station receives the call signal sequence by using a line terminator 21, supplies it to a transmitter 22 and a code information signal detecting circuit 23, and stores it in a memory 24. Terminals 16-1 and 16-2 for radio paging which receive call signals addressed to themselves from the call signal sequence sent from the base stations return answer signals after direct spread modulation by using the codes of the code information signals added to the call signals. The answer signals are received by a direct spread modulation signal receiver 25 of the base station 14. At this time, the receiver 25 uses a code determined with code information signals stored in the memory 24 as a spread code for answer signal reception. |
