System and method for providing external receiver gain compensation when using an antenna with a pre-amplifier
First Claim
1. A communications system configured to improve a noise figure (NF) of a time division duplex (TDD) communications system, the system comprising:
- a pre-amplified antenna unit comprising a first plurality of antennas and first associated low-noise amplifiers (LNA) contained therein, each of said first associated LNA'"'"'s being arranged to receive a signal from a first phase-matched pair of antennas selected from the plurality of antennas; and
a variable gain circuit coupled to a TDD output signal of at least one of the first associated LNA'"'"'s, wherein the variable gain circuit is configured to provide a selected negative gain to the TDD output signal, wherein the selected negative gain ensures that an output signal from the variable gain circuit is suitable for application to a remote radio head (RRH) input such that a dynamic range of the RRH input is not reduced below a desired dynamic range.
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Accused Products
Abstract
In various embodiments, a system and method for improving a noise figure (NF) of a time division duplex (TDD) communications system includes a pre-amplified antenna unit having a plurality of antennas and associated low-noise amplifiers (LNA). Each of the associated LNA'"'"'s is arranged to receive signals from a phase-matched pair of antennas selected from the plurality of antennas. For each of the phase-matched antenna pairs, a variable negative gain circuit may be coupled to a TDD signal output of the associated LNA such that a remote radio head (RRH) may be suitably coupled to an output of the variable gain circuit. The variable gain circuit is configured to provide a negative gain to the TDD signal appropriate to ensure that a dynamic range of the RRH is not reduced from a desired dynamic range due to excess gain provided by the LNA. A method of retrofitting a conventional pre-amplified antenna unit includes inserting a variable negative gain circuit so that the modified pre-amplified antenna may be used with any vendor'"'"'s RRH.
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Citations
29 Claims
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1. A communications system configured to improve a noise figure (NF) of a time division duplex (TDD) communications system, the system comprising:
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a pre-amplified antenna unit comprising a first plurality of antennas and first associated low-noise amplifiers (LNA) contained therein, each of said first associated LNA'"'"'s being arranged to receive a signal from a first phase-matched pair of antennas selected from the plurality of antennas; and a variable gain circuit coupled to a TDD output signal of at least one of the first associated LNA'"'"'s, wherein the variable gain circuit is configured to provide a selected negative gain to the TDD output signal, wherein the selected negative gain ensures that an output signal from the variable gain circuit is suitable for application to a remote radio head (RRH) input such that a dynamic range of the RRH input is not reduced below a desired dynamic range. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13)
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12. A communications system configured to improve a noise figure (NF) of a time division duplex (TDD) communications system, the system comprising:
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a pre-amplified antenna unit comprising a first plurality of antennas and first associated low-noise amplifiers (LNA) contained therein, each of said first associated LNA'"'"'s being arranged to receive a signal from a first phase-matched pair of antennas selected from the plurality of antennas; and a variable gain circuit coupled to a TDD output signal of at least one of the first associated LNA'"'"'s, wherein the variable gain circuit is configured to provide a selected negative gain to the TDD output signal, wherein said variable gain circuit comprises; a first circulator having a first port coupled to the at least one of the first associated LNA'"'"'s, a second port coupled to a receive signal path, and a third port coupled to a transmit signal path; an adjustable negative gain amplifier coupled to the second port and configured to receive the TDD signal output of the at least one of the first associated LNA'"'"'s at an input thereof; and a second circulator having a first port coupled to an output of the adjustable negative gain amplifier on the receive signal path, a second port coupled to an output terminal configured to provide an output to the RRH, and a third port coupled to the third port of the first circulator to form the transmit signal path, wherein the adjustable negative gain amplifier is configured to be adjusted to reduce a power level of the TDD signal output of the at least one of the first associated LNA'"'"'s to a lower power level so as to avoid overdriving an input of the RRH. - View Dependent Claims (14)
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15. A variable gain circuit configured to receive a time division duplex (TDD) communication signal from a pre-amplified antenna unit at a first power level and to output the communication signal to an external remote radio head (RRH) at a second power level different than the first power level, the circuit comprising:
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an input terminal configured to receive a pre-amplified TDD communication signal from a low-noise amplifier (LNA) in the pre-amplified antenna unit; a first circulator having a first port coupled to the input terminal, a second port coupled to a receive signal path, and a third port coupled to a transmit signal path; a variable negative gain amplifier coupled to the second port and configured to receive the pre-amplified TDD communication signal at an input thereof; a second circulator having a first port coupled to an output of the variable negative gain amplifier on the receive signal path, a second port coupled to an output terminal configured to provide an output to the external RRH, and a third port coupled to the third port of the first circulator to form the transmit signal path, wherein the variable negative gain amplifier is configured to be adjusted to reduce the first power level to the second power level so as to avoid overdriving the external RRH and undesirably reducing a dynamic range associated therewith. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22)
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23. A method of improving a noise figure (NF) of a time-division duplex (TDD) communications system comprising a pre-amplified antenna arrangement, a variable gain element, and a remote radio head (RRH) operatively coupled together, the method comprising:
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measuring a TDD signal power output by the pre-amplified antenna arrangement to an input of the RRH; determining whether the RRH input is being overdriven by the TDD signal power; if said RRH input is being overdriven, increasing a negative gain provided by the variable gain element so as to reduce a TDD signal power level provided to the RRH input; and if said RRH input is not being overdriven, maintaining a current negative gain setting of the variable gain element so as to at least temporarily set the TDD signal power level provided to the RRH input at predetermined power level, wherein the predetermined power level is established to maintain a full dynamic range of the RRH by avoiding overdriving the RRH input. - View Dependent Claims (24, 25, 26)
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27. A method of retrofitting a pre-amplified antenna unit configured to operate in a time-division duplex TDD communications system comprising a remote radio head (RRH), the method comprising:
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opening the pre-amplified antenna unit; opening one or more electrical connections between a low-noise amplifier (LNA) in the pre-amplified antenna unit and an output configured to connect to the RRH; operatively coupling a variable gain circuit between the LNA and the output, wherein the variable gain circuit is configured to provide a negative gain to a TDD communications signal output from the LNA so as to reduce a power level of the TDD communications signal passed therethrough, wherein the reduced power level TDD signal is provided as an input to the RRH, and wherein the negative gain is selected to avoid overdriving the input to the RRH and to preserve a desired dynamic range of the RRH. - View Dependent Claims (28, 29)
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Specification