Method and apparatus for frame detection in a communications system
First Claim
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1. A method of determining a boundary of a transmission structure in a time division duplexing (TDD) system comprising:
- detecting a power level of a radio frequency (RF) signal on at least one radio frequency, the RF signal comprising at least one subframe;
time-domain correlating the detected power level of the RF signal with a predetermined known first reference signal and with a predetermined known second reference signal, wherein the first reference signal represents at least one subframe; and
determining a location in time of a boundary of the at least one subframe of the detected RF signal based on the correlation of the detected power level of the RF signal with the first reference signal and the second reference signal;
wherein time-domain correlating the detected power level of the RF signal with the first and second reference signals further comprises;
correlating the first reference signal with the detected power level of the RF signal at a first point in time to calculate a correlation result for a maximum subframe overlap;
correlating the second reference signal with the detected power level of the RF signal at the first point in time to calculate a correlation result for a minimum subframe overlap;
summing the correlation results for the minimum subframe overlap and the maximum subframe overlap to calculate the correlation of the detected power level of the RF signal for a first point in time; and
time shifting the first and second reference signals relative to the detected power level of the RF signal.
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Abstract
A method of determining a boundary of a subframe in a time division duplexing (TDD) system is provided. The method detects a power level of a signal on at least one radio frequency, the signal comprising at least one subframe. A time-domain correlation is done on the detected signal with a first reference signal, wherein the first reference signal represents at least one subframe. The location in time of a boundary of the at least one subframe of the detected signal is determined based on the correlation of the detected signal and the first reference signal.
16 Citations
27 Claims
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1. A method of determining a boundary of a transmission structure in a time division duplexing (TDD) system comprising:
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detecting a power level of a radio frequency (RF) signal on at least one radio frequency, the RF signal comprising at least one subframe; time-domain correlating the detected power level of the RF signal with a predetermined known first reference signal and with a predetermined known second reference signal, wherein the first reference signal represents at least one subframe; and determining a location in time of a boundary of the at least one subframe of the detected RF signal based on the correlation of the detected power level of the RF signal with the first reference signal and the second reference signal; wherein time-domain correlating the detected power level of the RF signal with the first and second reference signals further comprises; correlating the first reference signal with the detected power level of the RF signal at a first point in time to calculate a correlation result for a maximum subframe overlap; correlating the second reference signal with the detected power level of the RF signal at the first point in time to calculate a correlation result for a minimum subframe overlap; summing the correlation results for the minimum subframe overlap and the maximum subframe overlap to calculate the correlation of the detected power level of the RF signal for a first point in time; and time shifting the first and second reference signals relative to the detected power level of the RF signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of switching in a time division duplexing (TDD) system comprising:
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detecting a power level of a radio frequency (RF) signal on at least one radio frequency, the RF signal comprising at least one subframe; time-domain correlating the detected power level of the RF signal with a predetermined known first reference signal, wherein the first reference signal represents at least one subframe; time-domain correlating the detected power level of the RF signal with a predetermined known second reference signal, wherein the first reference signal is associated with a maximum subframe length expected to be detected and the second reference signal is associated with a minimum subframe length expected to be detected; determining a location in time of a boundary of the at least one subframe of the detected RF signal based on the correlation of the detected power level of the RF signal with the first reference signal and the second reference signal; and switching between an uplink communication path and a downlink communication path based on the determination of the location in time of the boundary of a subframe. - View Dependent Claims (10, 11, 12)
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13. An apparatus for switching in a time division duplexing (TDD) system comprising:
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a switch having a first port coupled to an uplink communication path, and a second port coupled to a downlink communication path; a power level detector configured to measure a power level of radio frequency (RF) signals propagating through the switch; a processing device configured to time-domain correlate a power level of an RF signal detected by the power level detector, and comprising at least one subframe, with a predetermined known first reference signal representing at least one subframe, the processing device configured to control the switch based on the correlation between the detected power level of the RF signal and the first reference signal; wherein the processing device is further configured to correlate the detected power level of the RF signal with a predetermined known second reference signal, wherein the first reference signal is associated with a maximum subframe length expected to be detected and the second reference signal is associated with a minimum subframe length expected to be detected; wherein the processing device is further configured to sum the correlation of the first reference signal with the correlation of the second reference signal. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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21. A distributed antenna system comprising:
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at least one hub that is configured to communicate with a base station; a plurality of remote antenna units communicatively coupled to the at least one hub, wherein the system is configured to communicatively couple signals associated with the base station between the at least one hub and a plurality of wireless terminals; wherein the at least one hub further comprises; a switch having a first port coupled to an uplink communication path, and a second port coupled to a downlink communication path; a power level detector configured to measure a power level of a radio frequency (RF) signal propagating through the switch; a processing device configured to time-domain correlate the detected power level of the RF signal, the RF signal comprising at least one subframe, with a predetermined known first reference signal representing at least one subframe, the processing device configured to control the switch based on the correlation between the detected power level of the RF signal and the first reference signal; wherein the processing device is further configured to correlate the detected power level of the RF signal with a predetermined known second reference signal, wherein the first reference signal is associated with a maximum subframe length expected to be detected and the second reference signal is associated with a minimum subframe length expected to be detected; wherein the processing device is further configured to determine the location in time of a boundary of the subframe based on the correlation of the detected power level of the RF signal with the first reference signal and the second reference signal. - View Dependent Claims (22, 23, 24, 25, 26, 27)
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Specification