Abstract: An air circulation system includes at least one flow generator to generate an airflow, an air inlet, a first air outlet and a second air outlet each for exhausting airflow, an air conditioning device to air condition the exhausted airflow, and a controller. The controller is configured to position at least one of the first and second air outlets to be vertically separated from each other and to operate the flow generator to provide the exhaust airflow to the first and second air outlets. The exhaust airflow from the first and second air outlets are of different temperatures.

Abstract: Methods and apparatus for receiving a user message in a communication network are disclosed. In an exemplary embodiment, a method includes receiving data samples in an uplink transmission from user equipment, performing preamble detection on the data samples, generating a trigger signal that indicates when a preamble is detected, and decoding a user message in response to the trigger signal, wherein the user message follows the detected preamble.

Abstract: Methods and apparatus for distributing baseband signal processing of fifth generation (5G) new radio uplink signals. In an embodiment, a method includes receiving uplink transmissions having user data, receiving configuration parameters, and performing a first portion of baseband processing that compresses the uplink transmissions using the configuration parameters to generate compressed packets. The method also includes transmitting the compressed packets over a transmission medium to the central office that performs a second portion of the baseband processing to obtain the user data.

Abstract: Methods and apparatus for providing an adaptive beamforming antenna for OFDM-based communication systems. In one embodiment, a method includes forming a matrix (A) of cyclic prefix values and a matrix (B) of tail values from an orthogonal frequency division multiplexed (OFDM) symbol, and forming a summation matrix (S) and a difference matrix (D) from the matrix A and the matrix B. The method also includes multiplying a beamformer preset matrix (W) with the matrix S and the matrix D to determine a matrix (P) and a matrix (Q), and determining a beam identifier from the P and Q matrices.

Abstract: Methods and apparatus for preamble detection in a communication network are disclosed. In an exemplary embodiment, a method includes retrieving parameters from a parameter database, filling a buffer of preamble data received in an uplink transmission from user equipment, and frequency shifting the buffer of preamble data based on one or more first parameters to generate frequency shifted data. The method also includes oversampling the frequency shifted data to generates oversampled data, downsampling the over sampled data based on one or more second parameters to generate preamble samples, and updating the parameter database with updated values for the one or more first and second parameters. The method also includes repeating all the operations until a selected amount of preamble samples is obtained.

Abstract: Methods and apparatus for preamble detection in a communication network are disclosed. In an exemplary embodiment, a method includes retrieving parameters from a parameter database, filling a buffer of preamble data received in an uplink transmission from user equipment, and frequency shifting the buffer of preamble data based on one or more first parameters to generate frequency shifted data. The method also includes oversampling the frequency shifted data to generates oversampled data, downsampling the over sampled data based on one or more second parameters to generate preamble samples, and updating the parameter database with updated values for the one or more first and second parameters. The method also includes repeating all the operations until a selected amount of preamble samples is obtained.

Abstract: Methods and apparatus for providing an adaptive beamforming antenna for OFDM-based communication systems. In one embodiment, a method includes forming a matrix (A) of cyclic prefix values and a matrix (B) of tail values from an orthogonal frequency division multiplexed (OFDM) symbol, and forming a summation matrix (S) and a difference matrix (D) from the matrix A and the matrix B. The method also includes multiplying a beamformer preset matrix (W) with the matrix S and the matrix D to determine a matrix (P) and a matrix (Q), and determining a beam identifier from the P and Q matrices.

Abstract: Methods and apparatus for baseband signal compression of fifth generation new radio downlink signals. In an embodiment, a method includes receiving compressed packets over a transmission medium from a central office that performs a first portion of baseband processing to generate the compressed packets from downlink data, receiving configuration parameters, performing a second portion of baseband processing to decompress the compressed packets using the configuration parameters to generate the downlink data, and transmitting the downlink data. An apparatus includes an interface that receives compressed packets and configuration parameters over a transmission medium from a central office that includes a first baseband processing section that generate the compressed packets from downlink data.

Abstract: Methods and apparatus for providing an adaptive beamforming antenna for OFDM-based communication systems. In one embodiment, a method includes forming a matrix (A) of cyclic prefix values and a matrix (B) of tail values from an orthogonal frequency division multiplexed (OFDM) symbol, and forming a summation matrix (S) and a difference matrix (D) from the matrix A and the matrix B. The method also includes multiplying a beamformer preset matrix (W) with the matrix S and the matrix D to determine a matrix (P) and a matrix (Q), and determining a beam identifier from the P and Q matrices.

Abstract: Methods and apparatus for baseband signal compression of fifth generation new radio downlink signals. In an embodiment, a method includes receiving compressed packets over a transmission medium from a central office that performs a first portion of baseband processing to generate the compressed packets from downlink data, receiving configuration parameters, performing a second portion of baseband processing to decompress the compressed packets using the configuration parameters to generate the downlink data, and transmitting the downlink data. An apparatus includes an interface that receives compressed packets and configuration parameters over a transmission medium from a central office that includes a first baseband processing section that generate the compressed packets from downlink data.

Abstract: Methods and apparatus for fast Eigenvalue decomposition of Hermitian matrices are disclosed. In an exemplary embodiment, a method is provided for performing a decomposition iteration that includes identifying a largest off-diagonal term of a channel response matrix X, generating a 2×2 Hermitian matrix X2 that includes the largest off-diagonal term, and generating a 2×2 Unitary matrix ?2 from the 2×2 Hermitian matrix X2. The decomposition iteration also includes multiplying the 2×2 Unitary matrix ?2 with the 2×2 Hermitian matrix X2 to generate an updated largest off-diagonal term and updating the channel response matrix X with the updated largest off-diagonal term. The method also includes performing one or more additional decomposition iterations until all off-diagonal terms of the channel response matrix X are less than a target value.

Abstract: Methods and apparatus for frequency offset estimation are disclosed. In an exemplary embodiment, a method includes determining a demodulation reference signal (DMRS) frequency offset estimate from DMRS symbols in a received signal, and determining a cyclic prefix (CP) frequency offset estimate from cyclic prefix values in the received signal. The method also includes combining the DMRS and CP frequency offset estimates to determine a final frequency offset estimate. In an exemplary embodiment, an apparatus includes a DMRS frequency offset estimator that determines a DMRS frequency offset estimate based on DMRS symbols received in an uplink transmission, and a cyclic prefix (CP) frequency offset estimator that determines a CP frequency offset estimate based on cyclic prefix values in the uplink transmission. The apparatus also includes an offset combiner that combines the DMRS frequency offset estimate with the CP frequency offset estimate to generate a final frequency offset estimate.

Abstract: Methods and apparatus for providing an adaptive beamforming antenna for OFDM-based communication systems. In one embodiment, a method includes forming a matrix (A) of cyclic prefix values and a matrix (B) of tail values from an orthogonal frequency division multiplexed (OFDM) symbol, and forming a summation matrix (S) and a difference matrix (D) from the matrix A and the matrix B. The method also includes multiplying a beamformer preset matrix (W) with the matrix S and the matrix D to determine a matrix (P) and a matrix (Q), and determining a beam identifier from the P and Q matrices.

Abstract: Methods and apparatus for distributing baseband signal processing of fifth generation (5G) new radio uplink signals. In an embodiment, a method includes receiving uplink transmissions having user data, receiving configuration parameters, and performing a first portion of baseband processing that compresses the uplink transmissions using the configuration parameters to generate compressed packets. The method also includes transmitting the compressed packets over a transmission medium to the central office that performs a second portion of the baseband processing to obtain the user data.

Abstract: Methods and apparatus for frequency offset estimation are disclosed. In an exemplary embodiment, a method includes determining a demodulation reference signal (DMRS) frequency offset estimate from DMRS symbols in a received signal, and determining a cyclic prefix (CP) frequency offset estimate from cyclic prefix values in the received signal. The method also includes combining the DMRS and CP frequency offset estimates to determine a final frequency offset estimate. In an exemplary embodiment, an apparatus includes a DMRS frequency offset estimator that determines a DMRS frequency offset estimate based on DMRS symbols received in an uplink transmission, and a cyclic prefix (CP) frequency offset estimator that determines a CP frequency offset estimate based on cyclic prefix values in the uplink transmission. The apparatus also includes an offset combiner that combines the DMRS frequency offset estimate with the CP frequency offset estimate to generate a final frequency offset estimate.

Abstract: Methods and apparatus for providing an adaptive beamforming antenna for OFDM-based communication systems. In one embodiment, a method includes forming a matrix (A) of cyclic prefix values and a matrix (B) of tail values from an orthogonal frequency division multiplexed (OFDM) symbol, and forming a summation matrix (S) and a difference matrix (D) from the matrix A and the matrix B. The method also includes multiplying a beamformer preset matrix (W) with the matrix S and the matrix D to determine a matrix (P) and a matrix (Q), and determining a beam identifier from the P and Q matrices.

Abstract: Methods and apparatus for distributing baseband signal processing of fifth generation (5G) new radio uplink signals. In an embodiment, a method includes receiving uplink transmissions having user data, receiving configuration parameters, and performing a first portion of baseband processing that compresses the uplink transmissions using the configuration parameters to generate compressed packets. The method also includes transmitting the compressed packets over a transmission medium to the central office that performs a second portion of the baseband processing to obtain the user data.

Abstract: Methods and apparatus for distributing baseband signal processing of fifth generation (5G) new radio uplink signals. In an embodiment, a method includes receiving uplink transmissions having user data, receiving configuration parameters, and performing a first portion of baseband processing that compresses the uplink transmissions using the configuration parameters to generate compressed packets. The method also includes transmitting the compressed packets over a transmission medium to the central office that performs a second portion of the baseband processing to obtain the user data.

Abstract: Methods and apparatus for baseband signal compression of fifth generation new radio downlink signals. In an embodiment, a method includes receiving compressed packets over a transmission medium from a central office that performs a first portion of baseband processing to generate the compressed packets from downlink data, receiving configuration parameters, performing a second portion of baseband processing to decompress the compressed packets using the configuration parameters to generate the downlink data, and transmitting the downlink data. An apparatus includes an interface that receives compressed packets and configuration parameters over a transmission medium from a central office that includes a first baseband processing section that generate the compressed packets from downlink data.

Abstract: Methods and apparatus for providing an adaptive beamforming antenna for OFDM-based communication systems. In one embodiment, a method includes forming a matrix (A) of cyclic prefix values and a matrix (B) of tail values from an orthogonal frequency division multiplexed (OFDM) symbol, and forming a summation matrix (S) and a difference matrix (D) from the matrix A and the matrix B. The method also includes multiplying a beamformer preset matrix (W) with the matrix S and the matrix D to determine a matrix (P) and a matrix (Q), and determining a beam identifier from the P and Q matrices.