Channel sounding techniques
First Claim
1. A method, comprising:
- a channel sounding transmitter transmitting a repeated Constant Amplitude Zero Autocorrelation (CAZAC) sequence over a wireless channel in response to a first timing signal at the transmitter;
a channel sounding receiver receiving a circularly-shifted CAZAC sequence over the wireless channel in response to the transmission; and
processing the received circularly-shifted CAZAC sequence to generate a time of arrival (TOA) and a channel impulse response (CIR) estimate for the wireless channel, wherein the processing begins based on samples received after a point in time and includes correlation of received samples with at least a portion of a local version of the transmitted CAZAC sequence, wherein the point in time corresponds to the length of the CAZAC sequence after a second timing signal that is synchronized to occur at a same target time as the first timing signal, and wherein the correlation operates only on samples received after the point in time.
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Accused Products
Abstract
Techniques are disclosed relating to channel sounding. In some embodiments a transmitter transmits a periodic CAZAC sequence beginning at a point in time that corresponds to a timing signal (e.g., a pulse-per-second signal). In some embodiments, a receiver waits to begin processing received sequences for a time interval corresponding to the length of the CAZAC sequence, where the time interval begins at the same time as the timing signal. This may avoid a need for timing synchronization prior to processing, reduce processing and latency in receiver implementations, and may allow determination of a TOA as well as a channel impulse response estimate by correlating a received cyclically-shifted CAZAC sequence with a local version of the transmitted CAZAC sequence.
16 Citations
17 Claims
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1. A method, comprising:
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a channel sounding transmitter transmitting a repeated Constant Amplitude Zero Autocorrelation (CAZAC) sequence over a wireless channel in response to a first timing signal at the transmitter; a channel sounding receiver receiving a circularly-shifted CAZAC sequence over the wireless channel in response to the transmission; and processing the received circularly-shifted CAZAC sequence to generate a time of arrival (TOA) and a channel impulse response (CIR) estimate for the wireless channel, wherein the processing begins based on samples received after a point in time and includes correlation of received samples with at least a portion of a local version of the transmitted CAZAC sequence, wherein the point in time corresponds to the length of the CAZAC sequence after a second timing signal that is synchronized to occur at a same target time as the first timing signal, and wherein the correlation operates only on samples received after the point in time. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A system, comprising:
one or more processors configured to; receive a circularly-shifted Constant Amplitude Zero Autocorrelation (CAZAC) sequence from a wireless channel; detect a timing signal that is synchronized to occur at a same target time as a timing signal at a transmitter of the CAZAC sequence that is used by the transmitter to initiate transmission of the sequence, wherein the CAZAC sequence is transmitted in a repeated manner by the transmitter; and process the received circularly-shifted CAZAC sequence to generate a time of arrival (TOA) and a channel impulse response (CIR) of the wireless channel, wherein the processing begins based on samples received after a point in time and includes correlation of received samples with at least a portion of a local version of the transmitted CAZAC sequence, wherein the point in time corresponds to the length of the CAZAC sequence after the timing signal and wherein the correlation operates only on samples received after the point in time. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16)
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17. A non-transitory computer readable storage medium having stored thereon design information that specifies a design of at least a portion of a hardware circuit in a format recognized by a computing system configured to process the design information to implement the circuit according to the design, wherein the design information specifies that the implemented circuit includes:
one or more processors configured to; receive a circularly-shifted Constant Amplitude Zero Autocorrelation (CAZAC) sequence from a wireless channel; detect a timing signal that is synchronized to occur at a same target time as a timing signal at a transmitter of the CAZAC sequence that is used by the transmitter to initiate transmission of the sequence, wherein the CAZAC sequence is transmitted in a repeated manner by the transmitter; and process the received circularly-shifted CAZAC sequence to generate a time of arrival (TOA) and a channel impulse response (CIR) of the wireless channel, wherein the processing begins based on samples received after a point in time and includes correlation of received samples with at least a portion of a local version of the transmitted CAZAC sequence, wherein the point in time corresponds to the length of the CAZAC sequence after the timing signal and wherein the correlation operates only on samples received after the point in time.
Specification