Abstract: A wireless communication method includes receiving, by a first wireless device during a training phase, reference tones using a first number of resource elements from a transmitter of a second wireless device, wherein the first wireless device comprises multiple receiving antennas, estimating, by the first wireless device, from the receiving the reference tones, a second order statistics of wireless channels between the multiple receiving antennas and the transmitter of the second wireless device, and performing channel estimation, during an operational phase subsequent to the training phase, using the second order statistics and reference tones received on a second number of resource elements, wherein the second number is less than the first number.

Abstract: Methods, devices and systems for communication techniques that use the quasi-static properties of wireless channels are described. One example method to improve communication performance includes receiving a set of pilots over a transmission channel between the wireless communication apparatus and a far-end communication apparatus, the transmission channel comprising a first portion that is time-invariant and a second portion that is time-variant, processing the received set of pilots to generate an estimate of the first portion, processing the received set of pilots to generate an estimate of the second portion, and performing a communication based on a channel state information that is a weighted combination of a first term based on the estimate of the first portion and a second term based on the estimate of the second portion.

Abstract: Methods, systems and devices for providing transmission resources that achieve transmission diversity while reducing pilot signal overhead are described. An exemplary wireless communication method may be implemented in a wireless communication system in which transmission resources are allocated on a per physical resource block (PRB) basis, where a PRB corresponds to a two dimensional resource pattern comprising a first number of subcarriers along a frequency dimension and a second number time slots along a time dimension. The method includes logically dividing subcarriers in each PRB into an integer number of sub-groups of subcarriers, wherein the integer number is greater than one, allocating, to a transmission, transmission resources corresponding to one or more of the sub-groups of subcarriers, performing the transmission in the wireless communication system.

Abstract: A wireless communication method for transmitting wireless signals from a transmitter includes dividing bits of the transport block into a number of code blocks, wherein each code block corresponds to a bit-level of a multi-level modulation scheme used for transmission, and wherein a size of each code block is inversely proportional to a corresponding coding rate used for coding the code block.

Abstract: Methods, systems and devices for distributed cooperative operation of wireless cells based on sparse channel representations are described. One example method includes providing, using a server, seamless wireless connectivity in an area in which a plurality of network nodes are organized as clusters, where each network node is configured to provide wireless connectivity via N angular sectors covering a surrounding area, where N is an integer and wherein angular sectors of the plurality of network nodes collectively cover the area; controlling, by the server, network nodes in a cluster to collect channel condition information for the N angular sectors and communicate the channel condition information to the network-side server, and operating the server to use the channel condition information collected from the network nodes in the cluster to control communication for the network nodes in the cluster at a different time or a different frequency or a different spatial direction.

Abstract: Methods, systems and devices for forward error correction in orthogonal time frequency space (OTFS) communication systems using non-binary low-density parity-check (NB-LDPC) codes are described. One exemplary method for forward error correction includes receiving data, encoding the data via a non-binary low density parity check (NB-LDPC) code, wherein the NB-LDPC code is characterized by a matrix with binary and non-binary entries, modulating the encoded data to generate a signal, and transmitting the signal. Another exemplary method for forward error correction includes receiving a signal, demodulating the received signal to produce data, decoding the data via a NB-LDPC code, wherein the NB-LDPC code is characterized by a matrix with binary and non-binary entries, and providing the decoded data to a data sink.

Abstract: Orthogonal Time Frequency Space (OTFS) is a novel modulation scheme with significant benefits for 5G systems. The fundamental theory behind OTFS is presented in this paper as well as its benefits. We start with a mathematical description of the doubly fading delay-Doppler channel and develop a modulation that is tailored to this channel. We model the time varying delay-Doppler channel in the time-frequency domain and derive a new domain (the OTFS domain) where we show that the channel is transformed to a time invariant one and all symbols see the same SNR. We explore aspects of the modulation like delay and Doppler resolution, and address design and implementation issues like multiplexing multiple users and evaluating complexity. Finally we present some performance results where we demonstrate the superiority of OTFS.

Abstract: A fixed wireless access system is implemented using orthogonal time frequency space multiplexing (OTFS). Data transmissions to/from different devices share transmission resources using—delay Doppler multiplexing, time-frequency multiplexing, multiplexing at stream and/or layer level, and angular multiplexing. Time-frequency multiplexing is achieved by dividing the time-frequency plan into subgrids, with the subsampled time frequency grid being used to carry the OTFS data. Antenna implementations include a hemispherical antenna with multiple antenna elements arranged in an array to achieve multiplexing.

Abstract: Methods, systems and devices for lattice reduction in decision feedback equalizers for orthogonal time frequency space (OTFS) modulation are described. An exemplary wireless communication method, implementable by a wireless communication receiver apparatus, includes receiving a signal comprising information bits modulated using OTFS modulation scheme. Each delay-Doppler bin in the signal is modulated using a quadrature amplitude modulation (QAM) mapping. The method also includes estimating the information bits based on an inverse of a single error covariance matrix of the signal, with the single error covariance matrix being representative of an estimation error for all delay-Doppler bins in the signal.

Abstract: One example wireless communication method includes transforming an information signal to a discrete sequence, where the discrete sequence is a Zak transformed version of the information signal, generating a first ambiguity function corresponding to the discrete sequence, generating a second ambiguity function by pulse shaping the first ambiguity function, generating a waveform corresponding to the second ambiguity function, and transmitting the waveform over a wireless communication channel. Another communication method includes transforming an information signal to a discrete lattice domain signal, shaping bandwidth and duration of the discrete lattice domain signal by a two-dimensional filtering procedure to generate a filtered information signal, generating, using a Zak transform, a time domain signal from the filtered information signal, and transmitting the time domain signal over a wireless communication channel.

Abstract: An Orthogonal Time Frequency Space Modulation (OTFS) modulation scheme achieving multiple access by multiplexing multiple signals at the transmitter-side performs allocation of transmission resources to a first signal and a second signal, combining and converting to a transmission format via OTFS modulation and transmitting the signal over a communication channel. At the receiver, multiplexed signals are recovered using orthogonality property of the basis functions used for the multiplexing at the transmitter.

Abstract: Methods, systems and devices for forward error correction in orthogonal time frequency space (OTFS) communication systems using non-binary low-density parity-check (NB-LDPC) codes are described. One exemplary method for forward error correction includes receiving data, encoding the data via a non-binary low density parity check (NB-LDPC) code, wherein the NB-LDPC code is characterized by a matrix with binary and non-binary entries, modulating the encoded data to generate a signal, and transmitting the signal. Another exemplary method for forward error correction includes receiving a signal, demodulating the received signal to produce data, decoding the data via a NB-LDPC code, wherein the NB-LDPC code is characterized by a matrix with binary and non-binary entries, and providing the decoded data to a data sink.

Abstract: Methods, devices and systems for communication techniques that use the quasi-static properties of wireless channels are described. One example method to improve communication performance includes receiving a set of pilots over a transmission channel between the wireless communication apparatus and a far-end communication apparatus, the transmission channel comprising a first portion that is time-invariant and a second portion that is time-variant, processing the received set of pilots to generate an estimate of the first portion, processing the received set of pilots to generate an estimate of the second portion, and performing a communication based on a channel state information that is a weighted combination of a first term based on the estimate of the first portion and a second term based on the estimate of the second portion.

Abstract: A method for modulating data for transmission within a communication system. The method includes establishing a time-frequency shifting matrix of dimension N×N, wherein N is greater than one. The method further includes combining the time-frequency shifting matrix with a data frame to provide an intermediate data frame. A transformed data matrix is provided by permuting elements of the intermediate data frame. A modulated signal is generated in accordance with elements of the transformed data matrix.

Abstract: A system and method for orthogonal time frequency space communication and waveform generation. The method includes receiving a plurality of information symbols and encoding an N×M array containing the plurality of information symbols into a two-dimensional array of modulation symbols by spreading each of the plurality of information symbols with respect to both time and frequency. The two-dimensional array of modulation symbols is then transmitted using M mutually orthogonal waveforms included within M frequency sub-bands.

Abstract: A wireless communication method for transmitting wireless signals from a transmitter includes dividing bits of the transport block into a number of code blocks, wherein each code block corresponds to a bit-level of a multi-level modulation scheme used for transmission, and wherein a size of each code block is inversely proportional to a corresponding coding rate used for coding the code block.

Abstract: Methods, systems and devices for lattice reduction in decision feedback equalizers for orthogonal time frequency space (OTFS) modulation are described. An exemplary wireless communication method, implementable by a wireless communication receiver apparatus, includes receiving a signal comprising information bits modulated using OTFS modulation scheme. Each delay-Doppler bin in the signal is modulated using a quadrature amplitude modulation (QAM) mapping. The method also includes estimating the information bits based on an inverse of a single error covariance matrix of the signal, with the single error covariance matrix being representative of an estimation error for all delay-Doppler bins in the signal.

Abstract: An Orthogonal Time Frequency Space Modulation (OTFS) modulation scheme achieving multiple access by multiplexing multiple signals at the transmitter-side performs allocation of transmission resources to a first signal and a second signal, combining and converting to a transmission format via OTFS modulation and transmitting the signal over a communication channel. At the receiver, multiplexed signals are recovered using orthogonality property of the basis functions used for the multiplexing at the transmitter.

Abstract: A wireless data transmission technique includes encoding information bits as a periodic sequence of quadrature amplitude modulation (QAM) symbols, convolving the periodic sequence with a periodic pulse function, thereby generating a filtered periodic sequence, transforming the filtered periodic sequence to a delay-Doppler domain waveform, converting the delay-Doppler domain waveform to a time domain waveform, and transmitting the time domain waveform.

Abstract: In a transmitter apparatus, a known reference signal is superimposed on top of a data signal that is typically not known a priori to a receiver and the combined signal is transmitted. At a receiver, an iterative channel estimation and equalization technique is used to recover the reference signal and the unknown data signal. In the initial iteration, the known reference signal is recovered by treating the data signal as noise. Subsequent iterations are used to improve estimation of received reference signal and the unknown data signal.