Transmit leakage cancellation in a wide bandwidth distributed antenna system
First Claim
1. A method for transmission leakage cancellation in a wireless remote unit in a distributed antenna system (“
- DAS”
), the remote unit having a first signal path coupled to a transmission antenna and a second signal path coupled to a receiving antenna, comprising;
generating a pilot signal;
introducing the pilot signal in the first signal path;
generating a cancellation signal;
receiving a received signal having a transmission leakage signal at the receiving antenna;
providing the received signal to the second signal path; and
,cancelling the transmission leakage signal by adding the cancellation signal with the received signal over a bandwidth that is narrower than the bandwidth of the DAS,wherein an input to the cancellation signal is generated by adding the pilot signal and an output of a variable voltage attenuator.
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Accused Products
Abstract
A system and methods for cancelling transmission leakage signals in a wide bandwidth Distributed Antenna System (“DAS”) having remote units is disclosed. An internal cancellation circuit within the remote unit is employed to reduce the transmitted leakage signals by generating a cancellation signal. This cancellation signal is added to the received signal to cancel the transmission leakage signal in the receiving signal path. A pilot signal generation circuit is employed to optimize the cancellation circuit operating parameters. The frequency of the pilot signal is swept over a range to determine the pilot frequency having the highest electromagnetic coupling. The amplitude and phase of the cancellation signal is then optimized to minimize the level of transmission leakage in the receiving transmission path.
75 Citations
6 Claims
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1. A method for transmission leakage cancellation in a wireless remote unit in a distributed antenna system (“
- DAS”
), the remote unit having a first signal path coupled to a transmission antenna and a second signal path coupled to a receiving antenna, comprising;generating a pilot signal; introducing the pilot signal in the first signal path; generating a cancellation signal; receiving a received signal having a transmission leakage signal at the receiving antenna; providing the received signal to the second signal path; and
,cancelling the transmission leakage signal by adding the cancellation signal with the received signal over a bandwidth that is narrower than the bandwidth of the DAS, wherein an input to the cancellation signal is generated by adding the pilot signal and an output of a variable voltage attenuator. - View Dependent Claims (2, 3, 4, 5, 6)
- DAS”
Specification