Abstract: Systems, methods, and devices for wireless communication are included herein. An aspect of the subject matter described in the disclosure provides a device configured to detect a transmission. The device includes a receiver configured to receive an inductive communication signal having a center frequency. The device further includes an analog-to-digital converter configured to sample the signal at a rate higher than twice the center frequency. The device further includes one or more processors configured to digitally downconvert the signal. The processors are further configured to compare an energy of the downconverted signal to a detection threshold. The device further includes a transmitter configured to selectively transmit a communication based on the comparison.

Abstract: In a wireless communication system, an initiator, such as a card reader, can communicate with a target, such as a smart card or other device emulating a smart card, by amplitude modulating a radio frequency signal. In a receiver, levels of samples of a digital baseband signal of the amplitude modulated signal can vary. Apparatus and methods associate a received sample with a hard or sliced output state (such as +1, 0, or ?1) and update a value associated with the hard output state for accurate slicing of the samples. This permits the use of hard symbols in further processing rather than soft samples, which can dramatically reduce the complexity of circuitry.

Abstract: Systems, methods, and devices for wireless communication are included herein. An aspect of the subject matter described in the disclosure provides a device configured to detect a transmission. The device includes a receiver configured to receive an inductive communication signal having a center frequency. The device further includes an analog-to-digital converter configured to sample the signal at a rate higher than twice the center frequency. The device further includes one or more processors configured to digitally downconvert the signal. The processors are further configured to compare an energy of the downconverted signal to a detection threshold. The device further includes a transmitter configured to selectively transmit a communication based on the comparison.

Abstract: In a wireless communication system, an initiator, such as a card reader, can communicate with a target, such as a smart card or other device emulating a smart card, by amplitude modulating a radio frequency signal. In a receiver, levels of samples of a digital baseband signal of the amplitude modulated signal can vary. Apparatus and methods associate a received sample with a hard or sliced output state (such as +1, 0, or ?1) and update a value associated with the hard output state for accurate slicing of the samples. This permits the use of hard symbols in further processing rather than soft samples, which can dramatically reduce the complexity of circuitry.

Abstract: A method and apparatus for combining retransmitted hybrid automatic repeat-request (HARQ) messages divided into coding blocks in an orthogonal frequency-division multiplexing (OFDM)/orthogonal frequency-division multiple access (OFDMA) receiver are provided. According to such a coding-block-based HARQ combining scheme, the quality of each coding block may be compared to a threshold to determine whether the decoded bits or the HARQ combined signal should be saved for each coding block for subsequent HARQ iterations. In addition to reducing the required HARQ buffer size while preserving the combining gain, coding-block-based HARQ combining may also provide fast decoding and reduced power consumption when compared to conventional HARQ combining techniques.

Abstract: A method and apparatus for combining retransmitted hybrid automatic repeat-request (HARQ) messages at different stages in an orthogonal frequency-division multiplexing (OFDM)/orthogonal frequency-division multiple access (OFDMA) receiver are provided. The type of HARQ combiner used for a particular channel may depend on a number of selection criteria including the modulation order of the transmission, the number of bits needed for the combined signals, and the headroom in the HARQ buffer. For some embodiments, a combination of different types of HARQ combiners may be designed into a receiver and selected on a per-channel basis. Proper selection of a HARQ combining scheme may reduce the required HARQ buffer size and may provide an increased combining gain when compared to conventional HARQ combining techniques.

Abstract: Certain embodiments of the present disclosure provide techniques for channel estimation without resorting to the channel second-order statistics. Methods and systems are proposed for improving the performance of an un-constrained least squares channel interpolator by using available side information of the channel, such as signal-to-noise ratio (SNR), Doppler frequency and/or delay spread.

Abstract: A method and apparatus is provided for efficient processing of signal in a communication system. The processing of the signal for transmission may include encoding a block of data at an encoding rate 1/R. The encoding produces R number of data symbols for every data bit in the block of data. A block of RAM (299, 600) is partitioned into a plurality of blocks of RAM to allow reading simultaneously data symbols from the plurality of blocks of RAM to produce an in-phase and a quad-phase data symbols simultaneously. At least two scramblers (306 and 307) are used for simultaneously scrambling the in-phase and quad-phase data symbols. A Walsh covering/summing block (700) followed by the scramblers provides efficient Walsh covering and summing of signals for a combined transmission from the communication system.

Abstract: Certain embodiments of the present disclosure provide techniques for channel estimation without resorting to the channel second-order statistics. Methods and systems are proposed for improving the performance of an un-constrained least squares channel interpolator by using available side information of the channel, such as signal-to-noise ratio (SNR), Doppler frequency and/or delay spread.

Abstract: Space time coding (STC) may be applied at the transmitter adding redundant information in both space and time dimensions. At the receiver, the received STC signal may be decoded using a spatial multiplexing MIMO decoding, for example, based on either Minimum Mean Square Error (MMSE) or maximum-likelihood (ML) algorithms. A selective STC decoder may incorporate both the conventional maximum ratio combining (MRC) decoding scheme and a MIMO decoding scheme. One of the STC decoding schemes may be selected, for example, based on estimated channel conditions in order to achieve a trade-off between error rate performance and computational complexity. Components used for a non-selected scheme may be powered down.

Abstract: A method and apparatus for combining retransmitted hybrid automatic repeat-request (HARQ) messages at different stages in an orthogonal frequency-division multiplexing (OFDM)/orthogonal frequency-division multiple access (OFDMA) receiver are provided. The type of HARQ combiner used for a particular channel may depend on a number of selection criteria including the modulation order of the transmission, the number of bits needed for the combined signals, and the headroom in the HARQ buffer. For some embodiments, a combination of different types of HARQ combiners may be designed into a receiver and selected on a per-channel basis. Proper selection of a HARQ combining scheme may reduce the required HARQ buffer size and may provide an increased combining gain when compared to conventional HARQ combining techniques.

Abstract: A method and apparatus for combining retransmitted hybrid automatic repeat-request (HARQ) messages divided into coding blocks in an orthogonal frequency-division multiplexing (OFDM)/orthogonal frequency-division multiple access (OFDMA) receiver are provided. According to such a coding-block-based HARQ combining scheme, the quality of each coding block may be compared to a threshold to determine whether the decoded bits or the HARQ combined signal should be saved for each coding block for subsequent HARQ iterations. In addition to reducing the required HARQ buffer size while preserving the combining gain, coding-block-based HARQ combining may also provide fast decoding and reduced power consumption when compared to conventional HARQ combining techniques.

Abstract: An efficient method and apparatus for implementing a back-end channel matched filter in a receiver is disclosed. A typical channel matched filter embodiment includes a peak detector for establishing processing synchronization from a despread signal, a channel estimator producing a channel impulse response (CIR) estimate from the despread signal based on the synchronization by the peak detector and a back-end symbol combiner coherently combining dominant multipath components of the despread signal by weights based on the CIR estimate based on the synchronization by the peak detector to generate a decision variable. In a digital spread spectrum implementation, the despread signal operated on by the channel matched filter has been previously been correlated with a spreading sequence replica.

Abstract: A method and apparatus is provided for efficient processing of signal in a communication system. The processing of the signal for transmission may include encoding a block of data at an encoding rate 1/R. The encoding produces R number of data symbols for every data bit in the block of data. A block of RAM (299, 600) is partitioned into a plurality of blocks of RAM to allow reading simultaneously data symbols from the plurality of blocks of RAM to produce an in-phase and a quad-phase data symbols simultaneously. At least two scramblers (306 and 307) are used for simultaneously scrambling the in-phase and quad-phase data symbols. A Walsh covering/summing block (700) followed by the scramblers provides efficient Walsh covering and summing of signals for a combined transmission from the communication system.

Abstract: A method and apparatus for encoding multiple bits in parallel wherein outputs are generated recursively. During each clock cycle, the encoder processes multiple bits and generates outputs consistent with those generated sequentially over multiple clock cycles in a conventional convolutional encoder. In one embodiment, input data is stored in multiple memory storage units, which are then each uniquely addressed to provide data to parallel encoders.

Abstract: A method and apparatus is provided for efficient processing of signal in a communication system. The processing of the signal for transmission may include encoding a block of data at an encoding rate 1/R. The encoding produces R number of data symbols for every data bit in the block of data. A block of RAM is partitioned into a plurality of blocks of RAM to allow reading simultaneously data symbols from the plurality of blocks of RAM to produce an in-phase and a quad-phase data symbols simultaneously. At least two scramblers are used for simultaneously scrambling the in-phase and quad-phase data symbols. A Walsh covering/summing block followed by the scramblers provides efficient Walsh covering and summing of signals for a combined transmission from the communication system.

Abstract: An efficient method and apparatus for implementing a back-end channel matched filter in a receiver is disclosed. A typical channel matched filter embodiment includes a peak detector for establishing processing synchronization from a despread signal, a channel estimator producing a channel impulse response (CIR) estimate from the despread signal based on the synchronization by the peak detector and a back-end symbol combiner coherently combining dominant multipath components of the despread signal by weights based on the CIR estimate based on the synchronization by the peak detector to generate a decision variable. In a digital spread spectrum implementation, the despread signal operated on by the channel matched filter has been previously been correlated with a spreading sequence replica.

Abstract: A method and apparatus for efficient encoding of linear block codes uses a lookup table including a set of impulse responses to support faster performance by encoding in parallel. Advantages include a scalability that is lacking in existing schemes.

Abstract: A method and apparatus is provided for efficient processing of signal in a communication system. The processing of the signal for transmission may include encoding a block of data at an encoding rate 1/R. The encoding produces R number of data symbols for every data bit in the block of data. A block of RAM (299, 600) is partitioned into a plurality of blocks of RAM to allow reading simultaneously data symbols from the plurality of blocks of RAM to produce an in-phase and a quad-phase data symbols simultaneously. At least two scramblers (306 and 307) are used for simultaneously scrambling the in-phase and quad-phase data symbols. A Walsh covering/summing block 700 provides efficient Walsh covering and summing of signals for a combined transmission from the communication system.

Abstract: A method and apparatus for encoding multiple bits in parallel wherein outputs are generated recursively. During each clock cycle, the encoder processes multiple bits and generates outputs consistent with those generated sequentially over multiple clock cycles in a conventional convolutional encoder. In one embodiment, input data is stored in multiple memory storage units, which are then each uniquely addressed to provide data to parallel encoders.