| 摘要 |
A method of establishing or re-establishing a digital time-division duplex radio communication link between one of a plurality of portable units and one or more base units forming a cordless telephone system. The invention is concerned particularly with the potential interference created by the use of an unsynchronised call-up transmission in the presence of synchronised signals being exchanged by the rest of the system. The method of the invention involves pre-synchronising the call-up transmission with the rest of the system so that switchovers between transmission bursts and reception windows occur at the same time as between the call-up signal and the rest of the system. This is achieved by deriving synchronisation information from a synchronisation signal which may, for example, be an existing signal on the system containing synchronisation information (i.e. an existing call on the system) or may be a beacon signal which, in some systems, is transmitted by the fixed units for the purpose of range indication. The method is particularly applicable to the MUX1/MUX2/MUX3 format of signals used in the CT2 common air interface protocol. |
