Transport of signals over an optical fiber using analog RF multiplexing
First Claim
1. In a wireless communication network, a method comprising:
- a) generating at a base station a plurality of downlink RF signals having a common carrier frequency, frequency translating the downlink RF signals to produce corresponding IF downlink signals having distinct intermediate frequencies, combining the IF downlink signals to produce a combined downlink signal, and converting the combined downlink signal to a downlink optical signal centered at a downlink optical wavelength;
b) communicating the downlink optical signal over a single optical fiber to a remote site;
c) converting the downlink optical signal to recover the combined downlink signal, separating the combined downlink signal to recover the IF downlink signals, frequency translating the IF downlink signals to recover the downlink RF signals, and transmitting the downlink RF signals from antennas at the remote site;
d) receiving from the antennas at the remote site a plurality of uplink RF signals having a common carrier frequency, frequency translating the uplink RF signals to produce corresponding IF uplink signals having distinct intermediate frequencies, combining the IF uplink signals to produce a combined uplink signal, and converting the combined uplink signal to a uplink optical signal centered at an uplink optical wavelength;
e) communicating the uplink optical signal over the single optical fiber from the remote site;
f) converting the uplink optical signal to recover the combined uplink signal, separating the combined uplink signal to recover the IF uplink signals, and frequency translating the IF uplink signals to recover the uplink RF signals.
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Accused Products
Abstract
In a wireless communication network, a method for transporting signals between a base station hotel and a remote cell site allows multiple uplink and downlink signals to be communicated using a single optical fiber. In a preferred embodiment of the invention, an RF transport technique uses frequency translation to shift the common carrier frequencies of diversity and sector signals to distinct intermediate frequencies that are then combined, converted to an optical signal and transmitted over a single fiber. The RF transport technique also uses wavelength division multiplexing (WDM) to communicate both uplink and downlink signals over the same fiber. Reference clock signals are distributed to ensure accurate frequency translation at both ends of the link. Reference power signals are also transmitted in both uplink and downlink to help perform signal power equalization.
177 Citations
15 Claims
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1. In a wireless communication network, a method comprising:
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a) generating at a base station a plurality of downlink RF signals having a common carrier frequency, frequency translating the downlink RF signals to produce corresponding IF downlink signals having distinct intermediate frequencies, combining the IF downlink signals to produce a combined downlink signal, and converting the combined downlink signal to a downlink optical signal centered at a downlink optical wavelength;
b) communicating the downlink optical signal over a single optical fiber to a remote site;
c) converting the downlink optical signal to recover the combined downlink signal, separating the combined downlink signal to recover the IF downlink signals, frequency translating the IF downlink signals to recover the downlink RF signals, and transmitting the downlink RF signals from antennas at the remote site;
d) receiving from the antennas at the remote site a plurality of uplink RF signals having a common carrier frequency, frequency translating the uplink RF signals to produce corresponding IF uplink signals having distinct intermediate frequencies, combining the IF uplink signals to produce a combined uplink signal, and converting the combined uplink signal to a uplink optical signal centered at an uplink optical wavelength;
e) communicating the uplink optical signal over the single optical fiber from the remote site;
f) converting the uplink optical signal to recover the combined uplink signal, separating the combined uplink signal to recover the IF uplink signals, and frequency translating the IF uplink signals to recover the uplink RF signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A wireless communication system comprising:
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a) a base station for generating a plurality of downlink RF signals having a common carrier frequency;
b) a local hub comprising a frequency shifter for frequency translating the downlink RF signals to produce corresponding IF downlink signals having distinct intermediate frequencies, a splitter/combiner for combining the IF downlink signals to produce a combined downlink signal, and a WDM transceiver for converting the combined downlink signal to a downlink optical signal centered at a downlink optical wavelength;
c) an optical fiber for communicating the downlink optical signal to a remote site;
d) a remote hub comprising a WDM transceiver for converting the downlink optical signal to recover the combined downlink signal, and a splitter/combiner for separating the combined downlink signal to recover the IF downlink signals; and
e) a remote node comprising a frequency shifter for frequency translating the IF downlink signals to recover the downlink RF signals, and a transmitter for transmitting the downlink RF signals from antennas at the remote site. - View Dependent Claims (11)
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12. In a wireless communication network device, a method comprising:
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a) receiving from a base station a plurality of downlink RF signals having a common carrier frequency;
b) frequency translating the downlink RF signals to produce corresponding IF downlink signals having distinct intermediate frequencies;
c) combining the IF downlink signals to produce a combined downlink signal, d) converting the combined downlink signal to a downlink optical signal centered at a downlink optical wavelength;
e) transmitting the downlink optical signal over a single optical fiber to a remote site. - View Dependent Claims (13, 14, 15)
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Specification