Abstract: In order to provide a packet transfer scheme in which various data can easily be used commonly with other communication methods and a packet can be transferred at a high speed, a mobile communication system comprises a database (20) for storing an identification number of a mobile terminal (40) and location information indicating a zone in which the mobile terminal is currently located, a packet switch (10), and another packet switch (30) capable of communication when the mobile terminal (40) is located in a zone under the packet switch (30). The packet switch (10) inquires of the database (20) about the location information of the mobile terminal (40) when the packet switch (10) receives a packet addressed to the mobile terminal (40). When the mobile terminal (40) is located in the zone under the packet switch (30), the packet is transferred to the mobile terminal (40) through the packet switch (30).

Abstract: N signals are transmitted from each of N transmitting units to a receiving unit every signal transmission cycle (N.gtoreq.2). In this case, N signal transmitting periods of N I-th signals and (N-1) I-th transmission short pausing periods for each of the I-th transmitting units are alternately placed in each of I-th signal grouping periods (1.ltoreq.I.ltoreq.N), and an I-th transmission long pausing period follows each of the I-th signal grouping periods to set one signal transmission cycle composed of one I-th signal grouping period and one I-th transmission long pausing period for each of the I-th transmitting unit. A time length of each first transmission short pausing period is equal to that of the signal transmitting period, a time length of each I-th transmission short pausing period is (2N+2I-5) times as long as that of the signal transmitting period, and a time length of the signal transmission cycle is 4N(N-1) times as long as the signal transmitting period.

Abstract: The invention relates to the organization of phase references in a data transfer system based upon the multiplexing of orthogonal frequency components, when transmissions in the system are composed of relatively short symbol sequences. In accordance with the invention, in the first symbol (OS1) of the sequence differential phase-shift keying between elementary signals is carried out, based upon a phase reference (Ref) transmitted in one or several subfrequency bands (fc) and upon a phase shift chain propagated one subfrequency thereof at a time. In each subfrequency band in the subsequent symbols of the sequence phase-shift modulation refers to the elementary signal of the preceding symbol of the same subfrequency band. The invention may be applied with benefit to digital cellular network systems which employ the OFDM method.