Abstract: A mobile telecommunications system for a large area telecommunications system, including a plurality of different networks, has a directory/network structure for minimizing data storage and transmission and switching capacity requirements for locating roaming mobile terminals. A directory/network structure is provided with a plurality of directory/switching nodes arranged such that only one logical information and transmission path exists between any two nodes.

Abstract: The invention relates to a method of frame synchronization of a digital time-division multiplex communication system and to an arrangement for performing the method.During the search for a synchronization pattern of M bits in frames, each consisting of N time slots, a shift register of N.times.M bits is usually used. The method according to the invention has for its object to reduce the number of bit storage capacity required. The method operates as follows. At the start of the synchronization process the first bit of the synchronization pattern is expected. If this expectation comes true, the second bit of the synchronization pattern is expected in that time slot in the immediately subsequent frame etc. If the expectation does not come true then the (partially) received pattern is no synchronization pattern and the procedure is performed again in that time slot.