EP0795970A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Cellular radio system with simulcast transmission of delay-adjusted downlink signals to mobiles via adjacent base stations
Assignee: NEC Corp
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Filing: 1997-03-13
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Granted: —
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Expires: 2017-03-13
Abstract
Abstract In a cellular radio communication system, a downlink signal is multicast from a cental station and multiple base stations receive the multicast downlink signal via transmission links and respectively transmit the downlink signal on radio waves of same frequencies so that a cluster of adjoining areas is illuminated with the radio waves. A mobile station having a tapped-delay line equalizer receives signals from the base stations via multipath fading channels and equalizes the received signals. Interference between the transmitted signals is avoided by adjusting the relative propagation delay times of the transmission links so that the signals received by the mobile station occur within the tapped-delay line length of the equalizer.
Inventors
- 👤 Yuzo Kurokami
- 👤 Makoto Anzai
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-27 10:35
CPC Classifications
H; H04; H04B; H04B7/00; H04B7/02; H04B7/04; H04B7/06; H04B7/0613; H04B7/0667; H04B7/0671
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
107 words
A cellular radio communication system comprising: a central station for multicasting a downlink signal; a plurality of base stations for receiving the multicast downlink signal via transmission links and respectively transmitting the downlink signal on radio waves of same frequencies so that a plurality of adjoining areas are illuminated with the radio waves; a mobile station including a tapped-delay line equalizer for receiving signals from said base stations via multipath fading channels and equalizing the received signals; and means for adjusting relative propagation delay times of said transmission links so that the signals received by the mobile station occur within the tapped-delay line length of said equalizer.
Claim 2
Dependent Claim
144 words
A cellular radio communication system as claimed in claim 1, wherein said central station comprises a multiplexer for multiplexing the downlink signal with a pilot signal and transmitting the multiplexed signal to said transmission links, and wherein each of said base stations comprises: a demultiplexer for demultiplexing the signal from the corresponding transmission link into the downlink signal and the pilot signal; a phase-locked loop including a voltage-controlled oscillator for producing a radio frequency carrier, a frequency divider for dividing the frequency of the carrier, a phase comparator for comparing the pilot signal from the demultiplexer and the output of the frequency divider, and a lowpass filter for filtering the output of the phase comparator to produce a control signal for said voltage-controlled oscillator; and a transmitter for modulating the downlink signal from the demultiplexer onto the radio frequency carrier from the voltage-controlled oscillator.
Claim 3
Dependent Claim
36 words
A cellular radio communication system as claimed in claim 2, wherein said adjusting means comprises a plurality of variable delay means connected between the corresponding transmission links and the demultiplexer of each of said base stations.
Claim 4
Dependent Claim
35 words
A cellular radio communication system as claimed in claim 2 or 3, wherein said adjusting means comprises a plurality of variable delay means connected between the multiplexer of said central station and said transmission links.
Claim 5
Dependent Claim
18 words
A system as claimed in claim 2, 3 or 4, wherein said transmission links comprise electrical transmission mediums.
Claim 6
Independent Claim
95 words
A system as claimed in any one of claims 1 to 5, wherein said transmission links comprise optical transmission mediums and said central station comprises: a transmitter for modulating the downlink signal onto a radio frequency carrier; and an electrooptical converter for converting the modulated carrier to an optical signal and transmitting the optical signal to said transmission links, wherein each of said base stations comprises: an optoelectrical converter for converting the optical signal from the corresponding transmission link to an electrical signal; and a power amplifier for amplifying the electrical signal for radio transmission.
Claim 7
Dependent Claim
38 words
A cellular radio communication system as claimed in claim 6, wherein said adjusting means comprises a plurality of variable delay means each being connected between the optoelectrical converter and said power amplifier of each of said base stations.
Claim 8
Dependent Claim
66 words
A cellular radio communication system as claimed in claim 6 or 7, wherein said adjusting means comprises a plurality of variable delay means connected to the output of said transmitter, and wherein a plurality of said electrooptical converters are provided for converting the output signals of the variable delay means to a plurality of optical signals and respectively transmitting the optical signals to said transmission links.
References Cited (Backward Citations)
No citation records indexed.
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