Abstract: This disclosure provides systems, methods, and apparatus for reducing or avoiding interference between communications of one base station-user equipment pair and communications of another base station-user equipment pair. A first user equipment can monitor a timing offset between the communications and send the timing offset to a first base station that services the first user equipment. The first base station time advances a window of time during which it receives uplink signals from the first user equipment. The base station also sends a time advance value and instructions to the first user equipment to advance a window of time during which the first user equipment transmits uplink signals to the first base station. The timing advance value is based on the timing offset value determined by the first user equipment. Thus, a gap period between uplink and downlink windows is increased, thereby reducing interference.

Abstract: Systems, devices and techniques for wireless communications include receiving a plurality of wireless transmissions over an observation period from a transmitter of a mobile terminal, calculating a plurality of frequency offset values based on the received plurality of wireless transmissions and estimating a speed value based on the plurality frequency offset values. In some implementations, the speed value is determined as a function of a computed frequency offset measurement error. Implementations can be made to include estimating channel characteristics in communication between a base station and the mobile terminal based on the estimated speed and optimizing a property in communications with the mobile terminal based on the estimated channel characteristics. In some implementations, the property can include a modulation scheme or scheduling of transmissions for communications between the base station and the mobile terminal.

Abstract: A telecommunication system includes base stations, a backhaul network transmitters, a backhaul network in communication with the base stations, and a synchronizing system in communication with the base stations. The base stations are configured to transmit/receive signals to/from user equipment and the backhaul network is configured to convey information to and from at least one of the base stations. The synchronizing system is configured to synchronize a communication timing between the base stations over a synchronizing network. The synchronizing network is separate from the backhaul network and is configured to provide the communication timing between the synchronizing system and a corresponding synchronization port at each of the base stations.

Abstract: An improved DPD system includes a predistortion module having at least one predistortion function. The predistortion module is configured to receive and subsequently process a baseband signal. The system also includes a power amplifier configured to receive the processed baseband signal from the predistortion module. The system further includes a model calculator configured to program priorities for predistortion functions so that the processed baseband signal transmitted from the predistortion module corresponds to the transmission power of the power amplifier. The model calculator is further configured to send a trigger signal to indicate when data capture from the power amplifier should begin so as to update the predistortion functions. A trigger module in the system is configured to receive the trigger signal and to initiate data capture from the power amplifier upon receipt of the trigger signal.

Abstract: The disclosed methods and systems for improved OFDM channel estimation filtering take advantage of the presence of highly correlated adjacent subcarriers to reduce the computational intensiveness of channel estimation filtering. Specifically, baseband signals corresponding to a channel are received. The cyclic prefixes of the baseband signals are removed, and the resulting signal is transformed into the frequency domain, and compensated by a first time offset of the baseband receive signal. Subcarrier signals used to transmit the baseband signal are then extracted. Adjacent subcarriers having channel responses highly correlated to the subcarriers of the channel are identified, and the signal is compensated by a second time offset that corresponds to a minimal angle of the autocorrelation function of the subcarrier and adjacent subcarriers.

Abstract: The document discloses a pre-distorter, which comprises: a pre-distortion module, which is configured to pre-distort a plurality of baseband input signals by an equal number of pre-distortion functions to obtain an equal number of pre-distorted signals respectively, wherein all of the baseband input signals input into every pre-distortion function, and each pre-distortion function has one output; an adder, which is configured to combine all of the pre-distorted signals output from every pre-distortion function into one combined signal; and a power amplifier (PA), which is configured to amplify the combined signal, wherein the cascade of the pre-distortion functions and the PA are linear overall. And the document also discloses a method for distorting. The document reduces the implementation cost of a pre-distorter.

Abstract: Techniques for performing channel estimation in an orthogonal frequency domain multiplexing (OFDM) communications system include receiving a plurality of reference signals on a plurality of subcarriers, performing channel estimation to obtain a plurality of raw channel estimates based on the received plurality of reference signals, determining a number of raw channel estimates to be used for a channel estimate refinement and calculating a refined channel estimate using the number of raw channel estimates from the plurality of raw channel estimates.

Abstract: An improved DPD system includes a predistortion module having at least one predistortion function. The predistortion module is configured to receive and subsequently process a baseband signal. The system also includes a power amplifier configured to receive the processed baseband signal from the predistortion module. The system further includes a model calculator configured to program priorities for predistortion functions so that the processed baseband signal transmitted from the predistortion module corresponds to the transmission power of the power amplifier. The model calculator is further configured to send a trigger signal to indicate when data capture from the power amplifier should begin so as to update the predistortion functions. A trigger module in the system is configured to receive the trigger signal and to initiate data capture from the power amplifier upon receipt of the trigger signal.

Abstract: Systems, devices and techniques for wireless communications include receiving a plurality of wireless transmissions over an observation period from a transmitter of a mobile terminal, calculating a plurality of frequency offset values based on the received plurality of wireless transmissions and estimating a speed value based on the plurality frequency offset values. In some implementations, the speed value is determined as a function of a computed frequency offset measurement error. Implementations can be made to include estimating channel characteristics in communication between a base station and the mobile terminal based on the estimated speed and optimizing a property in communications with the mobile terminal based on the estimated channel characteristics. In some implementations, the property can include a modulation scheme or scheduling of transmissions for communications between the base station and the mobile terminal.

Abstract: An apparatus and method for compensating for transmit power losses that are caused by the addition of a clipping or crest factor reduction module in the TX path of a communications system. The method includes applying a gain to a signal input into the crest factor reduction module, so that a power of a signal output from the crest factor reduction module is equal to a power of a signal output from a baseband signal generation module in the TX chain. The apparatus and method have the benefit that the peaks of the signal to be transmitted will be consistent over a wide range of TX power values.

Abstract: The present invention discloses a pre-distorter, which comprises: a pre-distortion module, which is configured to pre-distort a plurality of baseband input signals by an equal number of pre-distortion functions to obtain equal number of pre-distorted signals respectively, wherein all of the baseband input signals input into every pre-distortion function, and each pre-distortion function has one output; an adder, which is configured to combine all of the pre-distorted signals output from every pre-distortion functions into one combined signal; and a power amplifier (PA), which is configure to amplify the combined signal, wherein the cascade of the pre-distortion functions and the PA are linear overall. And the present invention also discloses a method for distorting. The present invention reduces the implementation cost of a pre-distorer.

Abstract: An apparatus and method for linearizing a non-linear power amplifier. The method comprises: performing an iteration algorithm by using a desired output signal of the non-linear power amplifier, to calculate an input signal of the non-linear power amplifier, whereby with the calculated input signal of the non-linear power amplifier, the non-linear power amplifier is linearized. The apparatus and method can produce a signal on the output of the non-linear power amplifier with an arbitrarily high quality of performance.

Abstract: The disclosed methods and systems for improved OFDM channel estimation filtering take advantage of the presence of highly correlated adjacent subcarriers to reduce the computational intensiveness of channel estimation filtering. Specifically, baseband signals corresponding to a channel are received. The cyclic prefixes of the baseband signals are removed, and the resulting signal is transformed into the frequency domain, and compensated by a first time offset of the baseband receive signal. Subcarrier signals used to transmit the baseband signal are then extracted. Adjacent subcarriers having channel responses highly correlated to the subcarriers of the channel are identified, and the signal is compensated by a second time offset that corresponds to a minimal angle of the autocorrelation function of the subcarrier and adjacent subcarriers.

Abstract: Techniques for performing channel estimation in an orthogonal frequency domain multiplexing (OFDM) communications system include receiving a plurality of reference signals on a plurality of subcarriers, performing channel estimation to obtain a plurality of raw channel estimates based on the received plurality of reference signals, determining a number of raw channel estimates to be used for a channel estimate refinement and calculating a refined channel estimate using the number of raw channel estimates from the plurality of raw channel estimates.

Abstract: An apparatus and method for linearizing a non-linear power amplifier. The method comprises: performing an iteration algorithm by using a desired output signal of the non-linear power amplifier, to calculate an input signal of the non-linear power amplifier, whereby with the calculated input signal of the non-linear power amplifier, the non-linear power amplifier is linearized. The apparatus and method can produce a signal on the output of the non-linear power amplifier with an arbitrarily high quality of performance.

Abstract: A digital predistortion circuit and method with extended operating range includes a predistortion function, a D/A converter, a multiplier for performing frequency translation and a power amplifier. The digital predistortion circuit includes a multiplier for receiving a signal to be transmitted and a gain correction factor, multiplying the gain correction factor with the signal to be transmitted, and outputting a result of the multiplication to the predistortion function, as well as a device for calculating the gain correction factor by using a predetermined reference gain and an estimated gain of the power amplifier, and outputting the calculated gain correction factor to the multiplier, whereby a gain of the power amplifier is quickly corrected. The digital predistortion circuit and the method thereof produce acceptable results for a more expanded range of TX power levels.

Abstract: An apparatus and method for compensating for transmit power losses that are caused by the addition of a clipping or crest factor reduction module in the TX path of a communications system. The method includes applying a gain to a signal input into the crest factor reduction module, so that a power of a signal output from the crest factor reduction module is equal to a power of a signal output from a baseband signal generation module in the TX chain. The apparatus and method have the benefit that the peaks of the signal to be transmitted will be consistent over a wide range of TX power values.