Radio communication method and system for performing communication among a plurality of radio communication terminals

• US 7,302,236 B2
• Filed: 01/09/2003
• Issued: 11/27/2007
• Est. Priority Date: 02/18/2002
• Status: Expired due to Fees

• Current Assignee: National Institute of Information and Communications Technology
• Original Assignee: National Institute of Information and Communications Technology
• Inventors: Ogawa, Hiroyo, Hamaguchi, Kiyoshi, Shoji, Yozo
• Primary Examiner(s): Maung; Nay
• Assistant Examiner(s): Nguyen; Tuan H.
• Application Number:
  US10/504,059
• Publication Number:
  US 20050176377A1
• Time in Patent Office: 1,783 Days
• Field of Search: 455/42, 455/68, 455/500, 455/41.2, 455/41.3, 455255-259, 455265-266, 370/338
• US Class Current: 455/68
• CPC Class Codes: H03B 2202/027 the noise being essentially proportional to the inverse of the frequency, i.e. the so-called 1/f noise
• CPC Class Codes: H04B 1/405 with multiple discrete channels

Abstract

A reference local oscillation signal transmission station 1 radiates a reference local oscillation signal to a service zone. A portion of the signal received by each radio slave station terminal 2 is branched and fed to an injection locked oscillator 6. As a result, a local oscillation signal which is synchronized with the reference local oscillation signal is obtained. In the slave station terminal 2, the thus-obtained local oscillation signal is fed to a transmission frequency converter (mixer) 7 and a reception frequency converter (mixer) 8. An IF band transmission modulated signal is fed to the mixer 7 for frequency conversion to a radio frequency band, and the thus-obtained radio-frequency modulated signal is transmitted. Meanwhile, a received radio-frequency modulated signal is fed to the mixer 8 for down conversion, and the thus-obtained signal is fed to an IF band demodulator 10 so as to restore an information signal. The present invention not only solves the problem of deterioration of signal quality stemming from phase noise and frequency offset generated in a millimeter wave band oscillator, but also improves the efficiency of frequency use.

Claims

1. A radio communication method for communications between a plurality of radio communication terminals, wherein each of the plurality of radio communication terminals has a transmission section in which a product of an intermediate-frequency-band modulated signal and a local oscillation signal is obtained so as to generate a radio-frequency modulated signal, and a reception section in which a product of the radio-frequency modulated signal and a local oscillation signal is obtained for down conversion to an intermediate-frequency-band modulated signal, the method being characterized in that

each of the plurality of radio communication terminals has an injection locked oscillator whose state is switched to either of a master mode and a slave mode by means of a switch;

a selected one of the plurality of radio communication terminals which serves as a base station or master station is switched to the master mode by controlling the switch, so that the selected radio communication terminal uses, as a local oscillation signal, a free-run signal from the injection locked oscillator, and transmits, along with a radio-frequency modulated signal, the free-run signal as a reference local oscillation signal; and

each of the remaining radio communication terminals, which serve as slave stations, is switched to the slave mode by controlling the switch, so that each of the remaining radio communication terminals receives and amplifies the reference local oscillation signal transmitted from the base station or the master station, passes the amplified reference local oscillation signal through a band-pass filter, feeds the filtered reference local oscillation signal to the injection locked oscillator so as to reproduce the reference local oscillation signal, and uses the reference local oscillation signal as the local oscillation signals in frequency conversion sections of the transmission section and the reception section.

2. A radio communication system for communications between a plurality of radio communication terminals, wherein each of the plurality of radio communication terminals has a transmission section in which a product of an intermediate frequency-band modulated signal and a local oscillation signal is obtained so as to generate a radio-frequency modulated signal, and a reception section in which a product of the radio-frequency modulated signal and a local oscillation signal is obtained for down conversion to an intermediate-frequency-band modulated signal, the system being characterized in that

each of the plurality of radio communication terminals has an injection locked oscillator whose state is switched to either of a master mode and a slave mode by means of a switch;

a selected one of the plurality of radio communication terminals which serves as a base station or master station is switched to the master mode by controlling the switch, so that the selected radio communication terminal uses, as a local oscillation signal, a free-run signal from the injection locked oscillator, and transmits, along with a radio-frequency modulated signal, the free-run signal as a reference local oscillation signal; and

each of the remaining radio communication terminals, which serve as slave stations, is switched to the slave mode by controlling the switch, so that each of the remaining radio communication terminals receives and amplifies the reference local oscillation signal transmitted from the base station or the master station, passes the amplified reference local oscillation signal through a band-pass filter, feeds the filtered reference local oscillation signal to the injection locked oscillator so as to reproduce the reference local oscillation signal, and uses the reference local oscillation signal as the local oscillation signals in frequency conversion sections of the transmission section and the reception section.