Abstract: Aspects of the present disclosure are directed to radar apparatuses and methods involving the communication of data with radar signals. As may be implemented with one or more embodiments, a sequence of radar waveforms are transmitted as RF signals, the RF signals carrying communication data encoded onto a ramped radar carrier signal via phase-shift keying (PSK) modulation. Such modulation may utilize a modified, reduced-angle modulation with phase angles of less than ?. Object-reflected versions of the RF signals are received and demodulated by deramping the received object-reflected versions of RF signals using a linearized version of the radar waveforms (e.g., without PSK modulation). This approach can mitigate compression peak loss.

Abstract: Aspects of the present disclosure are directed to radar apparatuses and methods involving the communication of data with radar signals. As may be implemented with one or more embodiments, a sequence of radar waveforms are transmitted as RF signals, the RF signals carrying communication data encoded onto a ramped radar carrier signal via phase-shift keying (PSK) modulation. Such modulation may utilize a modified, reduced-angle modulation with phase angles of less than ?. Object-reflected versions of the RF signals are received and demodulated by deramping the received object-reflected versions of RF signals using a linearized version of the radar waveforms (e.g., without PSK modulation). This approach can mitigate compression peak loss.

Abstract: Aspects of the present disclosure are directed to decoding signals susceptible to communication errors. As may be implemented in accordance with one or more embodiments, an input signal is decoded to produce a first decoded output, which is subsequently encoded, and error characteristics of the encoded first decoded output are assessed. The input signal is again decoded (e.g., with a delay), using the encoded first decoded output and the assessed error characteristics thereof to assess a reliability characteristic of bits in the input signal. A second decoded output is then provided with errors corrected therein based on the assessed reliability characteristic.

Abstract: Aspects of the present disclosure are directed to decoding signals susceptible to communication errors. As may be implemented in accordance with one or more embodiments, an input signal is decoded to produce a first decoded output, which is subsequently encoded, and error characteristics of the encoded first decoded output are assessed. The input signal is again decoded (e.g., with a delay), using the encoded first decoded output and the assessed error characteristics thereof to assess a reliability characteristic of bits in the input signal. A second decoded output is then provided with errors corrected therein based on the assessed reliability characteristic.

Abstract: An input selector for selecting an input of a convolution encoder of a transmitter is disclosed. The input selector comprises a shaper block and an input-select block. The shaper block is configured to receive an input comprising a first number of input bits, the shaper block configured to generate a shaped bit stream corresponding to the first number of input bits. The input-select block is configured to generate an encoder input bit stream for the encoder based on the shaped bit stream, wherein the input-select block generates the encoder input bit stream such that, when input into the encoder, a first bit of the encoder input bit stream sets a state of the encoder in order that a subsequent second bit of the encoder input bit stream causes the encoder to generate a bit of the shaped bit stream at a pre-determined position in an encoder output bit stream.

Abstract: Certain aspects of the disclosure are directed to a method for communicating data from a transmitting circuit to a receiving circuit over a noisy channel. The method can be performed by logic circuitry, and can include encoding data, for transmission over the noisy channel. The data can be encoded, as a shaped-coded modulation signal by shaping the signal based on an amplitude selection algorithm that leads to a symmetrical input and by constructing a trellis having a bounded-energy sequence of amplitude values selected by computing and storing a plurality of channel-related energy constraints based on use of a nonlinear-estimation process, and therein providing an index for the bounded-energy sequence of amplitudes. The method can also include receiving over the noisy channel, the shaped-coded modulation signal, and decoding the data from the shaped-coded modulation signal by using the index to reconstruct the bounded-energy sequence of amplitudes.

Abstract: A method for k-bit Enumerative Sphere Shaping (ESS) of multidimensional constellations includes converting a first set of a plurality of uniformly distributed data bits from a serial data bit stream to a first unsigned amplitude sequence comprising a plurality of amplitudes bounded by a spherical constellation of maximum energy levels of a plurality of energy levels, wherein the first unsigned amplitude sequence has a Gaussian distribution and each of the energy levels is determined by a respective one of the amplitudes in the amplitude sequence. The first unsigned amplitude sequence is converted to a first shaped data bit sequence. The first shaped data bit sequence is combined with a second set of a one or more uniformly distributed data bits from the serial data bit stream to form a combined data stream. The combined data stream is mapped to a combined amplitude stream.

Abstract: Certain aspects of the disclosure are directed to a method for communicating data from a transmitting circuit to a receiving circuit over a noisy channel. The method can be performed by logic circuitry, and can include encoding data, for transmission over the noisy channel. The data can be encoded, as a shaped-coded modulation signal by shaping the signal based on an amplitude selection algorithm that leads to a symmetrical input and by constructing a trellis having a bounded-energy sequence of amplitude values selected by computing and storing a plurality of channel-related energy constraints based on use of a nonlinear-estimation process, and therein providing an index for the bounded-energy sequence of amplitudes. The method can also include receiving over the noisy channel, the shaped-coded modulation signal, and decoding the data from the shaped-coded modulation signal by using the index to reconstruct the bounded-energy sequence of amplitudes.

Abstract: A method of processing a signal by non-uniform quantization of log likelihood ratios is disclosed. A method comprising the steps of: receiving a plurality of bits; calculating a log likelihood ratio, known as a LLR, for each bit; providing a LLR value for each bit based on the calculated LLR; quantizing the LLR values into a plurality of quantization bins, each quantization bin having: a width representative of one or more LLR values; and an index value having a bit length; and associating each bit with the index value that corresponds to its LLR value, wherein the width of each quantization bin is non-uniform. This compresses the LLR values in a more efficient manner, requiring lower memory usage and/or lower bandwidth. A chip for a receiver and a communication system comprising one or more receivers are also disclosed.

Abstract: An input selector for selecting an input of a convolution encoder of a transmitter is disclosed. The input selector comprises a shaper block and an input-select block. The shaper block is configured to receive an input comprising a first number of input bits, the shaper block configured to generate a shaped bit stream corresponding to the first number of input bits. The input-select block is configured to generate an encoder input bit stream for the encoder based on the shaped bit stream, wherein the input-select block generates the encoder input bit stream such that, when input into the encoder, a first bit of the encoder input bit stream sets a state of the encoder in order that a subsequent second bit of the encoder input bit stream causes the encoder to generate a bit of the shaped bit stream at a pre-determined position in an encoder output bit stream.

Abstract: According to the present disclosure, there is provided methods of processing a signal using quantized symbols. More particularly, in one example, the method comprises the steps of processing a signal (206), said method comprising the steps of: receiving a signal (206) comprising a plurality of raw symbols, each raw symbol having a plurality of bits and being conveyed in a channel; estimating a channel state information value (206) of the channel used to convey each raw symbol to generate a corresponding plurality of channel state information values; quantizing the plurality of raw symbols based on their channel state information values to generate a sequence of quantized symbols (214); and quantizing the channel state information values to generate a sequence of quantized channel state values (216).

Abstract: A receiver for a modulated signal of a communication system is disclosed. The receiver includes a demodulator to demodulate the received modulated symbols of a received signal into received soft-bits. The receiver also includes a hard-decision decoder that is configured to decode the received soft-bits into decoded bits. A feedback loop is included to provide feedback from the hard decision decoder to the demodulator. The feedback loop is configured to re-encode the decoded bits from the hard-decision decoder into re-encoded bits. The demodulator is further configured to iteratively demodulate the received modulated signal using an output of the feedback loop.

Abstract: Receivers and methods of operation are described. A receiver for a modulated signal of a communication system, comprises a demodulator to demodulate the received modulated symbols of a received signal into received soft-bits. A hard-decision decoder is arranged and configured to decode the received soft-bits into decoded bits. A feedback loop is arranged to provide feedback from the hard decision decoder to the demodulator. the feedback loop is configured to re-encode the decoded bits from the hard-decision decoder into re-encoded bits. The demodulator is further arranged and configured to iteratively demodulate the received modulated signal using an output of the feedback loop.

Abstract: Embodiments of systems and methods for performing channel estimation on Orthogonal frequency-division multiplexing (OFDM) signals are described. In one embodiment, a method for performing channel estimation on an OFDM signal involves performing blind channel phase estimation on an OFDM signal to obtain channel phase information and performing blind channel magnitude estimation on the OFDM signal to obtain channel magnitude information. Each of performing blind channel phase estimation on the OFDM signal and performing blind channel magnitude estimation on the OFDM signal involves detecting and suppressing a signal path of the OFDM signal. Other embodiments are also described.

Abstract: According to the present disclosure, there is provided methods of processing a signal using quantized symbols. More particularly, in one example, the method comprises the steps of processing a signal (206), said method comprising the steps of: receiving a signal (206) comprising a plurality of raw symbols, each raw symbol having a plurality of bits and being conveyed in a channel; estimating a channel state information value (206) of the channel used to convey each raw symbol to generate a corresponding plurality of channel state information values; quantizing the plurality of raw symbols based on their channel state information values to generate a sequence of quantized symbols (214); and quantizing the channel state information values to generate a sequence of quantized channel state values (216).

Abstract: The present invention relates to a transmitting apparatus, a receiving apparatus, a system, a signal, and a method of multi-user transmission, wherein transmission settings are divided into common signal information, containing settings/information relevant for multiple receivers and user stream specific information, containing settings/information relevant only to a related user stream. Furthermore, the common signal information may comprise at least one of a duration of the longest user stream field and multi-user resource allocation field, so that the receivers know the mapping of user streams to receivers.

Abstract: A method of processing a signal by non-uniform quantization of log likelihood ratios is disclosed. In particular a disclosed method comprising the steps of: receiving (110) a plurality of bits (12); calculating (120) a log likelihood ratio (22), known as a LLR, for each bit; providing (130) a LLR value (22) for each bit based on the calculated LLR; quantizing (140) the LLR values into a plurality of quantization bins, each quantization bin having: a width representative of one or more LLR values; and an index value (32) having a bit length; and associating (150) each bit with the index value (32) that corresponds to its LLR value (22), wherein the width of each quantization bin is non-uniform. This compresses the LLR values (22) in a more efficient manner, requiring lower memory usage and/or lower bandwidth. A chip for a receiver and a communication system comprising one or more receivers are also disclosed.

Abstract: Embodiments of systems and methods for performing channel estimation on Orthogonal frequency-division multiplexing (OFDM) signals are described. In one embodiment, a method for performing channel estimation on an OFDM signal involves performing blind channel phase estimation on an OFDM signal to obtain channel phase information and performing blind channel magnitude estimation on the OFDM signal to obtain channel magnitude information. Each of performing blind channel phase estimation on the OFDM signal and performing blind channel magnitude estimation on the OFDM signal involves detecting and suppressing a signal path of the OFDM signal. Other embodiments are also described.

Abstract: A processor (110) is disclosed for processing a plurality of Fourier-transformed instances of a symbol, each instance being comprised in one of a plurality of frequency-divided multiplexed subcarriers, said processor being arranged to estimate, for each instance, the channel gain and the inter-carrier interference contribution to said symbol from neighboring subcarriers due to a time-varying channel response of the received signal, and combine the instances into a single representation of said symbol based on the estimated channel gain and the inter-carrier interference contributions. A receiver comprising such a processor and a method for processing such signals are also disclosed.

Abstract: A channel frequency response estimator for estimating the channel frequency response of a wireless RF channel having a time or frequency varying channel frequency response is disclosed. The channel frequency response estimator includes a wireless receiver. An ambiguous channel frequency response estimator is also included and configured to establish multiple channel frequency response estimate candidates for the channel frequency response of the channel. An ambiguity resolver is configured to select a channel frequency response estimate from the multiple channel frequency response estimate candidates that maximizes a goodness of fit of the selected first channel frequency response estimate, and at least two further channel frequency response estimates to a channel model. The channel model models the time or frequency dependent variance of the channel frequency response.