US 4,057,758 AGranted

Mobile diversity radio communication system

AssigneeNippon Telegraph & Telephone Public Corporation

InventorsTakeshi Hattori, Fumiyuki Adachi

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Abstract

A diversity system in a mobile radio communication system provided with a plurality of antenna systems operating over a multipath medium in at least one of the sending path and the receiving path. At the sending path, a carrier wave frequency- or phase-modulated by a digital baseband signal is transmitted from a transmitting antenna. A plurality of receiving antenna systems are switched at a constant frequency higher than the signaling rate of the digital baseband signal but less than the frequency shift width of the frequency modulated wave or less than a product of the maximum phase shift of the phase modulated wave and the signaling rate, so that average-power dispersion in a signal element of the digital baseband signal received at the receiving antenna systems is effectively compressed. Alternatively, the plurality of antennas may be transmitting antennas, and switched at the same rate to achieve compression of average power dispersion in the baseband signal elements.

Claims18

Dependent claims

In a mobile diversity radio communication system, for operating over a multipath medium, of the type including a base station and at least one mobile station, wherein at least one of said stations comprises transmitting means for transmitting radio signals to another station of the system, wherein at least the other station comprises receiving means for receiving radio signals from said transmitting means, an antenna system for radiating the radio signals being transmitted and an antenna system for receiving said radio signals, and wherein at least one of said stations includes a plurality of antenna systems for operating in a space diversity mode, the improvement which comprises:

said transmitting means comprising modulation means for frequency shift modulating the radio signals being transmitted by a digital baseband signal;
and
switching means connected to said plurality of antenna systems operable for switching between ones of said antenna systems to render ones of said antenna systems active at a constant rate which rate is higher than the signaling rate of the digital baseband signal but less than the frequency shift width of the frequency shift modulated radio signal, being transmitted thereby to compress average-power dispersion in a signal element of the digital baseband signal.

said transmitting means comprising modulation means for phase modulating the radio signals being transmitted by a digital baseband signal;
and
switching means connected to said plurality of antenna systems and operable for switching between ones of said antenna systems to render ones of said antenna systems active at a constant rate which rate is higher than the signaling rate of the digital baseband signal but less than a product of the maximum phase shift of the phase-modulated radio signal and the signaling rate of the digital baseband signal, thereby to compress average-power dispersion in a signal element of the digital baseband signal.

Dependencies are inferred from the claim text.