摘要:
The invention relates to the formation of a wide-band data transfer link (WB) as an extension to a data transfer system, which comprises narrow frequency bands (f2) for the organization of narrow-band data transfer calls using one frequency band. In accordance with the invention the data stream (S) which is to be trans-mitted is divided into substreams (S5 - S9), each of which modulates a different frequency band (f5 - f9). The signals thus obtained are combined (C) for trans-mission. The received signal is divided into frequency bands, which are de-modulated separately, and from the data substreams thus obtained the original data stream is reconstructed. The wide-band communication in accordance with the invention (WB) may further be divided among many users on the principle of time or frequency-division multiple access.
摘要:
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 said 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.
摘要:
The invention relates to a communication method for a digital cellular mobile telephone system and a digital cellular mobile telephone system comprising several base stations and mobiles utilizing time division multiple access. In the system communication is carried out on a predetermined frequency band in a predetermined number of time slots having a predetermined length. In the communication between the mobiles and the base station within the TDMA time slot with the predetermined length, the transmissions to communicate information comprising a few bits or several bits from the mobiles communicating with the same base station at least within the same time slot are mutually substantially orthogonal. Preferably, in order to communicate information, preferably information of the on-off type, such as acknowledgments and channel allocation requests, the mobiles communicating with the same base station use substantially orthogonal transmissions at least to the same base station in the same time slot. Preferably each mobile transmits within the TDMA burst of said TDMA time slot of the predetermined length as a part of the burst a predetermined bit sequence corresponding to the transmitted information bit combination, whereby the predetermined frequency band is unchanged. The bit sequences transmitted by different mobiles to the same base station are mutually substantially orthogonal. By using such substantially orthogonal transmissions it is possible to avoid collisions between the communications of information comprising a few or several bits, typically 1 to 10 bits, such as acknowledgments and channel allocation requests, which typically occur in a time division multiple access system.
摘要:
A digital mobile radio communication system, in which a burst of speech or data, is transmitted, and an error check is carried out for each burst and when the burst is incorrect, information about the incorrect burst is transmitted to the transmitter. Hereby, the transmitter retransmits the same burst or a burst containing information related thereto, preferably prior to producing a subsequent burst. With the procedure the delay in transmission can be made shorter.
摘要:
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 said 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.
摘要:
The invention relates to the formation of a wide-band data transfer link (WB) as an extension to a data transfer system, which comprises narrow frequency bands (f2) for the organization of narrow-band data transfer calls using one frequency band. In accordance with the invention the data stream (S) which is to be trans-mitted is divided into substreams (S5 - S9), each of which modulates a different frequency band (f5 - f9). The signals thus obtained are combined (C) for trans-mission. The received signal is divided into frequency bands, which are de-modulated separately, and from the data substreams thus obtained the original data stream is reconstructed. The wide-band communication in accordance with the invention (WB) may further be divided among many users on the principle of time or frequency-division multiple access.
摘要:
The invention relates to a communication method for a digital cellular mobile telephone system and a digital cellular mobile telephone system comprising several base stations and mobiles utilizing time division multiple access. In the system communication is carried out on a predetermined frequency band in a predetermined number of time slots having a predetermined length. In the communication between the mobiles and the base station within the TDMA time slot with the predetermined length, the transmissions to communicate information comprising a few bits or several bits from the mobiles communicating with the same base station at least within the same time slot are mutually substantially orthogonal. Preferably, in order to communicate information, preferably information of the on-off type, such as acknowledgments and channel allocation requests, the mobiles communicating with the same base station use substantially orthogonal transmissions at least to the same base station in the same time slot. Preferably each mobile transmits within the TDMA burst of said TDMA time slot of the predetermined length as a part of the burst a predetermined bit sequence corresponding to the transmitted information bit combination, whereby the predetermined frequency band is unchanged. The bit sequences transmitted by different mobiles to the same base station are mutually substantially orthogonal. By using such substantially orthogonal transmissions it is possible to avoid collisions between the communications of information comprising a few or several bits, typically 1 to 10 bits, such as acknowledgments and channel allocation requests, which typically occur in a time division multiple access system.