Frequency converter and radio communications system employing the same

A radio communications system comprising a hub station and at least one subscriber station radio linked to the hub station, wherein

• the subscriber station communicates with the hub station by converting a signal in a first frequency band to a signal in a second frequency band by successively mixing the signal in the first frequency band with a plurality of subscriber station local-oscillation signals having different frequencies,
• the hub station transmits, to the subscriber station, a beacon signal having a radio frequency that is generated by mixing a signal having a hub station local-oscillation frequency with a beacon signal having a predetermined hub station intermediate frequency, and
• the subscriber station comprises an LC oscillator for providing a first one of the subscriber station local-oscillation signals in a quasi millimeter bandwidth or a millimeter bandwidth;
• and a phase-locked loop,
• wherein the phase-locked loop generates at least one of the subscriber station local-oscillation signals having a lowest frequency among the plurality of local-oscillation signals, based on an intermediate frequency beacon signal, which is generated by mixing the radio frequency beacon signal with another one of the subscriber station local-oscillation signals, and
• wherein the first frequency band and the second frequency band fall in a quasi millimeter bandwidth or a millimeter bandwidth.

A radio frequency converter for converting a signal in a first frequency band which is above a predetermined radio frequency to a signal in a second frequency band which is above the predetermined radio frequency by successively mixing the signal in the first frequency band with a plurality of local-oscillation signals having different frequencies, the frequency converter comprising an LC oscillator for providing a first one of the local-oscillation signals in a quasi millimeter bandwidth or a millimeter bandwidth;

• and a phase-locked loop,
• wherein a spread spectrum reference signal having a predetermined frequency and the first local-oscillation frequency signal are mixed into an intermediate frequency signal which is despread to result in a reference signal,
• wherein based on the reference signal, the phase-locked loop generates at least a second one of the local-oscillation signals having a lowest frequency among the plurality of local-oscillation signals having the different frequencies is generated, and
• wherein the first frequency band and the second frequency band fall in a quasi millimeter bandwidth or a millimeter bandwidth.

A radio communications system comprising a hub station and at least one subscriber station radio linked to the hub station, wherein the subscriber station communicates with the hub station by converting a signal in a first frequency band which is above a predetermined radio frequency to a signal in a second frequency band which is above the predetermined radio frequency by successively mixing the signal in the first frequency band with a plurality of subscriber station local-oscillation signals having different frequencies,

• the hub station transmits, to the subscriber station, a spread spectrum signal that is generated by spreading a predetermined reference signal and then by mixing a hub station local-oscillation frequency signal with the spread spectrum reference signal, and
• the subscriber station comprises an LC oscillator for providing a first one of the subscriber station local-oscillation signals in a quasi millimeter bandwidth or a millimeter bandwidth;
• and a phase-locked loop,
• wherein the phase-locked loop generates at least a second one of the subscriber station local-oscillation signal having a lowest frequency among the plurality of subscriber station local-oscillation signals used in the subscriber station from a reference signal that is obtained by despreading a subscriber station intermediate frequency signal which results from mixing the spread spectrum signal transmitted from the hub station and the first subscriber station local-oscillation frequency signal, and
• wherein the first frequency band and the second frequency band fall in a quasi millimeter bandwidth or a millimeter bandwidth.