Method and transmitter unit for synchronisation in a CDMA system

Method of synchronisation in a CDMA radio access system comprising one or more fixed units and various remote units. Within the coverage cell or cells, the fixed units communicate with the remote units by making use of a CDMA or TDM/CDMA radio frame. To facilitate synchronisation, the method is characterised by the division of the time slot(s) T carrying information into two sub-fields, one S for transmitting a synchronism pattern, and the other V/D for transmitting the signal with user data, encoded voice or signalling. The simultaneous CDMA channels transmitted by the fixed unit or units, use different, allocated spreading codes PN(i, j) during the voice or data sub-field, whereas in the synchronisation sub-fields they use a common code C(S)i. In the uplink direction, from remote units to fixed unit, each remote unit employs a unique spreading code that is common for the synchronisation sub-fields of the various synchronous CDMA channels transmitted in the same time slot.