EP4674093A1 - Communication de signal d'espace temps-fréquence orthogonal à l'aide de signaux de base prédéfinis - Google Patents

Communication de signal d'espace temps-fréquence orthogonal à l'aide de signaux de base prédéfinis

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Publication number
EP4674093A1
EP4674093A1 EP24764679.7A EP24764679A EP4674093A1 EP 4674093 A1 EP4674093 A1 EP 4674093A1 EP 24764679 A EP24764679 A EP 24764679A EP 4674093 A1 EP4674093 A1 EP 4674093A1
Authority
EP
European Patent Office
Prior art keywords
signal
pilot symbols
grid
delay
communication channel
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
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EP24764679.7A
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German (de)
English (en)
Inventor
Shachar Kons
Shlomo Selim Rakib
Ronny Hadani
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Cohere Technologies Inc
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Cohere Technologies Inc
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Publication date
Application filed by Cohere Technologies Inc filed Critical Cohere Technologies Inc
Publication of EP4674093A1 publication Critical patent/EP4674093A1/fr
Pending legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2626—Arrangements specific to the transmitter only
    • H04L27/2627—Modulators
    • H04L27/2639—Modulators using other transforms, e.g. discrete cosine transforms, Orthogonal Time Frequency and Space [OTFS] or hermetic transforms
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
    • H04L1/0041—Arrangements at the transmitter end
    • H04L1/0042—Encoding specially adapted to other signal generation operation, e.g. in order to reduce transmit distortions, jitter, or to improve signal shape
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
    • H04L1/0056—Systems characterized by the type of code used
    • H04L1/0071—Use of interleaving
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0202—Channel estimation
    • H04L25/0224—Channel estimation using sounding signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2602—Signal structure
    • H04L27/261—Details of reference signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2649—Demodulators
    • H04L27/26532—Demodulators using other transforms, e.g. discrete cosine transforms, Orthogonal Time Frequency and Space [OTFS] or hermetic transforms
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0202—Channel estimation
    • H04L25/0204—Channel estimation of multiple channels
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2602—Signal structure
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0048—Allocation of pilot signals, i.e. of signals known to the receiver

Definitions

  • an OTFS waveform may be generated using pre-defined basis signals called PulsonesTM.
  • a digital communication method includes receiving a signal over a communication channel, and determining an estimate of the communication channel from one or more pilot symbols in the signal.
  • the one or more pilot symbols are assigned along a delay-Doppler resource grid.
  • the method further includes equalizing one or more non-pilot symbols in the signal by rotating the estimate of the communication channel according to grid locations of the one or more pilot symbols along the 165524628.2 PCT Patent Application 119314.8090.WO00 delay-Doppler resource grid at other grid locations, and recovering data bits from one or more equalized non-pilot symbols.
  • another digital communication method includes generating a signal comprising one or more pilot symbols and one or more non-pilot symbols having transmission resources assigned along a delay-Doppler resource grid, and transmitting the signal over a communication channel.
  • the one or more pilot symbols are configured to enable (a) a determination of an estimate of the communication channel at a receiver, and (b) a recovery of data bits from the one or more non-pilot symbols by rotating the estimate of the communication channel based on grid locations of the one or more pilot symbols along the delay-Doppler resource grid at other grid locations.
  • a wireless communication apparatus that implements the above-described methods is disclosed.
  • the wireless communication apparatus may include a transmitter circuit and/or a receiver circuit to perform signal transmissions or receptions and a processor to implement various signal processing techniques described in the present document.
  • a wireless system in which one or more of the above- described methods are implemented is disclosed.
  • the method may be embodied as processor-executable code and may be stored on a computer-readable program medium.
  • FIG.1 shows an example communication network.
  • FIG.2 shows a simplified example of a wireless communication system in which uplink and downlink transmissions are performed.
  • FIG.3 is a block diagram of an example of a transmitter.
  • FIG.4 is a block diagram of an embodiment of signal generation.
  • FIG.5 is a block diagram of another embodiment of signal generation.
  • FIG.6 is a block diagram of yet another embodiment of signal generation.
  • FIG.7 is a block diagram of an example implementation.
  • FIG.8 shows an example of a hardware platform.
  • FIGS.9 and 10 are flowcharts for various example methods of digital communication.
  • FIG.11 shows examples of fully and partially overlapping OTFS frames.
  • FIG.12 shows an example of multiple OTFS frames with intervening synchronization signals (SS).
  • FIGS.13A and 13B show implementation examples of generation of OTFS waveforms that include synchronization signals.
  • FIG.14 depicts an example of an iterative decoder in which a single forward error correction (FEC) code is processed.
  • FIG.15 shows a block diagram of an example iterative receiver apparatus.
  • FIG.16 shows an example of an iterative decoder architecture when using a multi-level- coding (MLC) FEC code.
  • MLC multi-level- coding
  • FIG.17 shows a block diagram of an example iterative receiver apparatus that uses multi-level decoding.
  • DETAILED DESCRIPTION [0028] To make the purposes, technical solutions and advantages of this disclosure more apparent, various embodiments are described in detail below with reference to the drawings. Unless otherwise noted, embodiments and features in embodiments of the present document may be combined with each other. [0029] Section headings are used in the present document to improve readability of the description and do not in any way limit the discussion or the embodiments to the respective sections only. Furthermore, certain standard-specific terms are used for illustrative purpose only, and the disclosed techniques are applicable to any wireless communication systems. [0030] 1.
  • the wireless or time-variant nature of the communication channel poses several challenges in design a transmission protocol suitable for wireless communication scenarios. These days, users expect their wireless devices to work everywhere and in a variety of mobile or stationary situations. [0032] The relative movement of transmitters and receivers with respect to each other cause signal distortions such as varying channel delay, Doppler and/or angular spread, signal degradation due to ground clutter, sea clutter, and so on. Another example of signal degradation is flat fading in which an entire channel occupied by a transmission signal will experience fading or attenuation that may be relatively constant across the channel. In practice, a transmission scheme may need to be designed to fit within a certain link budget, maximum power constraint, or linearity of electronics used for transmitting or receiving signals.
  • FIG.1 shows an example of a wireless communication system 100 in which a transmitter device 102 transmits signals to a receiver 104.
  • the signals may undergo various wireless channels and multipaths, as depicted. Some reflectors such as buildings and trees may be static, while others such as cars, may be moving scatterers.
  • the transmitter device 102 may be, for example, a user device, a mobile phone, a tablet, a computer, or another Internet of Things (IoT) device such as a smartwatch, a camera, and so on.
  • the receiver device 104 may be a network device such as the base station.
  • FIG.2 shows a simplified wireless network to highlight certain aspects of the disclosed technology.
  • a transmitter transmits wireless signals to a receiver in the wireless network.
  • a network-side node such as a base station acts as a transmitter of wireless signals and one or more user devices act as the receiver of these wireless signals.
  • the direction of transmission may be reversed.
  • Such transmissions are often called uplink or upstream transmissions.
  • one or more user devices act as transmitters of the wireless signals and a network-side node such as the base station acts as the receiver of these signals (as depicted in FIG.2).
  • Other type of transmissions in the network may include device-to-device transmissions, sometimes called direct or sideband transmissions.
  • the disclosed techniques may also be described using terms such as “inbound” and “outbound” transmission without importing any 3GPP- specific or other wireless protocol-specific meaning to the terms “uplink” and “downlink.” 165524628.2 PCT Patent Application 119314.8090.WO00 [0036]
  • FDM frequency division multiplexing
  • TDM time division multiplexing
  • the OTFS waveform is constructed from symbols assigned to a grid in a two- dimensional domain called the delay-Doppler.
  • the grid is characterized by a Doppler period ⁇ ⁇ , typically satisfying ⁇ ⁇ ⁇ 2 ⁇ ⁇ ⁇ , where ⁇ ⁇ is the maximum expected Doppler shift, and a delay period, ⁇ ⁇ ⁇ 1/ ⁇ ⁇ .
  • the grid has ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ elements along Doppler and ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ elements along delay, where ⁇ ⁇ of the OTFS signal and ⁇ is its duration.
  • the grid may include pilot symbols used for channel detection and estimation.
  • the OTFS waveform in the time domain may be considered to be a super-position of PulsonesTM multiplied by the grid elements ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ , ⁇ ⁇ ⁇ ⁇ ⁇ , ⁇ ⁇ ⁇ (1) [0040] where ⁇ ⁇ ⁇ , ⁇ ⁇ are ⁇ ⁇ ⁇ , ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇
  • the PulsonesTM may be considered to be basis signals used for the delay-Doppler grid.
  • [0043] In to the effective duration of the time window ⁇ ⁇ . 165524628.2 PCT Patent Application 119314.8090.WO00
  • 3.1 Example Implementations using Zak Theory [0045] In signal processing, it is traditional to represent signals (or waveforms) either in time or in the frequency domain. Each representation reveals different attributes of the signal.
  • Zak domain a Zak signal is a function of two variables.
  • the variable is called delay and the variable is called Doppler.
  • the function is assumed to be periodic along with period and quasi-periodic along with .
  • This factorization is referred to as the Zak factorization.
  • the Zak embodies the combinatorics of the fast Fourier transform algorithm.
  • Zak transforms are principally geometric projections: the time Zak transform is integration along the Doppler variable and reciprocally the frequency Zak transform is integration along the delay variable.
  • the information bits are encoded on the frequency domain as a signal x(f) and transmitted through the rule: [0051] where the filtering is done on the frequency domain by linear convolution with a 1D pulse w(f) (in case of standard OFDM w(f) is equal an sinc function).
  • the modulation mapping is the Fourier transform.
  • TDMA the information bits are encoded on the time domain as a signal x(t) and transmitted through the rule: [0052] where the filtering is done on the time domain by linear convolution with a 1D pulse w(t).
  • the modulation mapping in this case is identity.
  • the OTFS transceiver can be mathematically interpreted from the point of view of realization theory.
  • this approach one considers the signal space of waveforms as a representation space of the Heisenberg group or equivalently as a Hilbert space equipped with collection of Heisenberg operators, each associated with a different point in the delay Doppler plane.
  • This representation space admits multitude of realizations. The two standard ones are the time and frequency realizations and they are related through the one- dimensional Fourier transform.
  • a delay Doppler lattice is an integral span of a pair of linear independent vectors .
  • the associated lattice is the set:
  • the vectors are called the lattice basis vectors. It is convenient to arrange the basis vectors as the first and second columns of a matrix , i.e.,: the lattice , that is, the image of the standard lattice under the matrix G.
  • the volume of the lattice is by definition the area of the fundamental domain which is equal to the absolute value of the determinant of G.
  • Every lattice admits a symplectic reciprocal lattice, aka orthogonal complement lattice that we denote by .
  • the definition of is: [0059]
  • an under-sampled lattice is that the volume of its fundamental domain is > 1. From this point on we consider only under-sampled lattices.
  • a lattice is rectangular if .
  • a sub-lattice of a rectangular lattice is also rectangular.
  • a rectangular lattice is under-sampled if > 1.
  • the interesting attribute of the hexagonal lattice is that among all critically sampled lattices it has the longest distance between neighboring points.
  • the maximal rectangular sub-lattice of ⁇ ⁇ is generated by ⁇ ⁇ and 2 ⁇ ⁇ ⁇ ⁇ ⁇ .
  • an OTFS transceiver structure depends on the choice of the following parameters: a critically sampled lattice , a filter function and an information grid specified by .
  • a critically sampled lattice a filter function
  • an information grid specified by .
  • the filter function where the delay and Doppler factors are square root Nyquist with to respectively.
  • the information bits were encoded as a periodic 2D with periods (N, M).
  • Multiplying by the standard Zak signal P we obtain a Zak P.
  • We define the modulated transmit proceeds in three steps. In the first step the information block is quasi-periodized thus transformed into a discrete Zak signal.
  • the bandwidth and duration of the signal are shaped through a 2D filtering procedure defined by twisted convolution with the pulse w.
  • the filtered signal is transformed to the time domain through application of the Zak transform.
  • the Zak transform obeys the relation: can be expressed as twisted convolution . can write: [0066] where in time.
  • Formula (3.3) the transmit from the bare waveform through windowing in time followed by convolution with a pulse.
  • the OTFS transmitter encodes information bits in one or more Forward-Error-Correction (FEC) codes, corresponding to one or more symbol constellation levels (denoted by ⁇ ), interleave the coded bits and map them to symbols (typically QAM) which are then assigned to delay-Doppler grid elements. Some of the delay-Doppler grid elements may not be assigned with any symbols (value of zero) and others may be assigned with known symbols (pilots). Finally, the OTFS modulator is applied to the delay-Doppler grid.
  • FIG.3 shows an example of such a transmitter. [0071] FIG.3 shows an example of generating an OTFS waveform.
  • source bits e.g., data bits
  • FEC coded outputs are interleaved through corresponding interleavers.
  • the resulting signals are mapped to symbols and mapped to a delay-Doppler grid along with pilot signals.
  • the resulting mapped signal is processed through an OTFS modulator to generate n OTFS waveform.
  • OTFS modulator implements equation (1), generating a time-domain signal ⁇ ⁇ .
  • FIG.4 shows a method of OTFS waveform generation in which the delta trains ⁇ ⁇ , ⁇ ⁇ ⁇ ⁇ are multiplied by the delay-Doppler grid elements ⁇ ⁇ ⁇ , ⁇ ⁇ .
  • FIG.5 shows an embodiment in which the convolution operation is performed before adding the resulting signals together. In other words, signal is composed in the Doppler domain.
  • FIG.6 shows the example where PulsonesTM are multiplied by grid elements and the result is combined to obtain the transmission waveform. [0077] Note, that there may be other equivalent implementation of equations (1)-(3).
  • the time-domain signal can be rewritten as ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ , ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ (4) [0078] [0079] 6. [0080]
  • the basis signals may combine certain mathematical properties of a pulse and a tone, and may be called PulsonesTM.
  • Channel estimation may be performed by assigning to one or more delay-Doppler grid elements a known symbol (pilot) at the transmitter.
  • the received signal may be processed for finding out the grid elements and their values where the pilot symbol was transformed to by the channel interaction.
  • a receiver will transform the estimated channel response obtained from the pilot to other locations on the grid, by rotating it: h ⁇ ⁇ ⁇ ⁇ , ⁇ ⁇ ⁇ h ⁇ ⁇ ⁇ ⁇ , ⁇ , ⁇ , ⁇ , ⁇ , ⁇ , ⁇ (5) [0084]
  • ⁇ ⁇ ⁇ ⁇ is a grid dimensions ⁇ ⁇ ⁇ .
  • the receiver-side applies a rotation that is of the x- and y- coordinates of the grid location in the two-dimensional (2D) delay-Doppler grid, the x- 165524628.2 PCT Patent Application 119314.8090.WO00 and y- coordinates of the pilot location in the 2D delay-Doppler grid, and the height and width dimensions of the 2D delay-Doppler grid.
  • the equalization in the delay-Doppler domain that applies the rotation described above can be incorporated into the iterative decoder and iterative receiver architecture seen in FIGS.14 and 15 (which use a single FEC code), and FIGS.16 and 17 (which use an MLC FEC code), respectively.
  • the iterative decoder uses for an input the received delay-Doppler grid of dimensions ⁇ ⁇ ⁇ .
  • a received grid element is denoted by ⁇ ⁇ , ⁇ , where ⁇ ⁇ 0,1, ... , ⁇ ⁇ 1 and ⁇ ⁇ 0,1, , ... , ⁇ ⁇ 1.
  • the channel estimation module extracts the channel response h, from the channel estimation area in the delay-Doppler grid.
  • a delay-Doppler equalizer generates A Posteriori probability estimation of the data symbols, ⁇ ⁇ ⁇ ⁇ , based on ⁇ , h and the a priori probability ⁇ ⁇ ⁇ ⁇ , which is fed-back from a previous iteration of the decoder.
  • a symbol demapper module computes bit Log-Likelihoods Ratios (LLRs), ⁇ , from the a posteriori probability, ⁇ ⁇ ⁇ ⁇ . Extrinsic LLRs are derived by subtracting from ⁇ , the a priori LLRs, ⁇ ⁇ , computed in the previous iteration.
  • the extrinsic LLRs may be deinterleaved and then they are fed into the FEC for decoding. If decoding is successful, the decoded information bits are passed to the next module following the iterative decoder for further processing. If decoding is not successful, the FEC will output coded bit LLRs, which may be interleaved and then fed into the symbol mapper as, ⁇ ⁇ .
  • the symbol mapper computes symbol a priori symbol probabilities, ⁇ ⁇ ⁇ ⁇ ⁇ , for the next iteration. Iterations are terminated, when there is a successful decoding in the FEC, or some other criterion is met, such as maximum number of iterations.
  • iterative receivers exchange extrinsic information between the equalizer and the FEC decoder to achieve close to optimal performance, as shown in FIG.15 for an OTFS receiver 400.
  • the extrinsic information may include a priori knowledge of which transmission resources (e.g., time slots of subcarriers) use which particular FEC.
  • the equalizer 402 uses prior information on the data symbols coming from the FEC feedback path to improve the equalization of the symbols.
  • This feedback path comprises a symbol mapper 410 and OTFS transformation module 412. Then, these symbols are converted to bit likelihoods that are FEC decoded. Several iterations are performed until all the source data is decoded correctly, or until some other stopping criteria is met.
  • An inverse OTFS transform module 404 may apply inverse OTFS transform and a symbol demapper 406 may recover bits from modulation symbols.
  • the error-rate performance of the scheme 400 may be degraded.
  • One reason for the degradation may be because of the mixture of bits 165524628.2 PCT Patent Application 119314.8090.WO00 with different level of reliability in every FEC codeword that is being decoded.
  • the constellation bits with low reliability make it harder for the FEC decoder to converge to the correct codeword and therefore, the feedback to the equalizer has less information to improve the equalization.
  • the basic iterative decoder is modified to accommodate it as well, e.g., using the iterative decoder in FIG.16.
  • the LLRs from the symbol demapper are split into the different levels, optionally deinterleaved and then fed to the different FEC decoders.
  • the coded bits LLRs output of the different FEC decoders are optionally interleaved and fed back to the symbol mapper.
  • the iterative receiver 550 in each decoding iteration, decodes only a part of the constellation bits. It typically starts with the most reliable bits and then proceeds in the next iterations to less reliable ones.
  • This scheme allows the equalizer to receive in earlier iterations priors, which are dominant from the constellation symbols point of view and better improve the equalization.
  • the FEC When the FEC has successfully decoded one level, it switches to decode the next one.
  • the receiver continues to iterate until all levels have been decoded successfully or until some other stopping criteria is met.
  • the most reliable bits are often bits that are used to decide the "macro" region within the constellation map where a symbol lies--e.g., the quadrant in which a constellation symbol of a 4 or 8 QAM signal lies, followed by sub-quadrant within the quadrant, and so on.
  • the received signal may be equalized by the equalizer 402.
  • the equalized signal may undergo an inverse OTFS transform (404), and the symbols from the resulting transformed signal may be demapped for decoding by multiple different FECs FEC1 to FECq (modules 558a to 558q).
  • the decoded symbol (bit) outputs of the FEC modules may be mapped to symbols (410) and transformed into OTFS domain signals (symbols) for feedback to the equalizer 402.
  • different forward error correction codes are used for symbols from the multiple symbols corresponding to header and payload portions of the bits from the signal.
  • An OTFS waveform generated as described herein may be described using PulsonesTM and may be used in a variety of different digital communication scenarios such as Under water acoustic wave communications, Deep-space communication, communication with non-terrestrial equipment such as satellites, airborne devices such as airplanes, balloons, drones, etc.
  • the communication channel in such cases may comprise aerial-to-ground, ground-to-aerial or ariel- to-ariel communication, underwater acoustic wave communication deep space communication 165524628.2 PCT Patent Application 119314.8090.WO00 and so on.
  • the disclosed techniques may be applied in generally any frequency range - from sub-MHz (e.g., underwater acoustics that uses 10 Hz to 1 MHz), MHz, GHz or THz and beyond.
  • sub-MHz e.g., underwater acoustics that uses 10 Hz to 1 MHz
  • MHz e.g., MHz
  • GHz e.g., GHz
  • THz THz
  • OTFS Synchronization Examples may be truncated to the effective duration of the time window ⁇ ⁇ . Therefore, multiple OTFS frames can be transmitted consecutively one after the other, as shown in FIG.11. As shown in FIG.11, multiple OTFS frames may be consecutively transmitted (or received) using multiple configurations.
  • each OTFS frame is characterized by a time window.
  • the multiple frames may be: non-overlapping (top graph), or partially overlapping (bottom graph).
  • the graphs show time dimension as horizontal axis and power or amplitude as the vertical axis.
  • a receiver should know where an OTFS frame begins. The duration of the frame is assumed to be known from a high-level configuration.
  • One possible method for synchronization is to add a known transmitted signal at the beginning of every ⁇ , OTFS frames, where ⁇ ⁇ 1, as shown in FIG.12. Multiple OTFS frames with synchronization sequences examples are shown in FIG.12.
  • the multiple time windows and synchronization sequences may be: non-overlapping (top) or partially overlapping (bottom).
  • This known transmitted signal which may also be referred to as a “Synchronization Sequence” is a sequence of ⁇ ⁇ symbols derived, for example from: [0097] – A Zadoff-Chu sequence [0098] – A pseudo-random sequence [0099] – An m-sequence [00100] – A Gold code sequence [00101] Typically, these sequences are generated using a generation parameter, such as a seed or a root number. [00102] The same Synchronization Sequence may be used each time, or at different instances of the sequence, a time-varying version of it may be used, according to rules known both to the transmitter and the receiver.
  • the length of the Synchronization Sequence, ⁇ ⁇ , and its periodicity, ⁇ are system parameters designed to meet different criterions such as SNR, latency, or throughput.
  • an OTFS receiver may receive the signal of more than one OTFS transmitters. For example, a cellular network with multiple cells and a receiver at a cell edge, receiving the signal from more than one cell transmitters.
  • the 165524628.2 PCT Patent Application 119314.8090.WO00 Synchronization Sequence generation parameters (such as a seed, or a root) may be different for different transmitters.
  • Another implementation may use at the same transmitter, different Synchronization Sequences to convey information to the receiver. Each Synchronization Sequences then, corresponds to a different configuration of the system. The different Synchronization Sequences may be generated from different generation parameters. The receiver will detect which one of the Synchronization Sequence was transmitted and apply the associated configuration. [00106] At the transmitter side, the Synchronization Sequence may be inserted before or after applying the delay pulse, ⁇ ⁇ ⁇ ⁇ , as shown in FIGS. 13A and 13B. [00107] Two implementation examples are depicted in FIGS.13A and 13B.
  • FIG.13A shows a scheme for multiplexing Synchronization Sequence (SS) after a full OTFS signal is generated
  • FIG.13B shows a scheme in which SS is multiplexed with the OTFS signal before the convolution with the delay pulse, ⁇ ⁇ .
  • FIG.8 is a block diagram representation of a wireless hardware platform 800 which may be used to implement the various methods described in the present document.
  • the hardware platform 800 may be incorporated within a base station or a user device.
  • the hardware platform 800 includes a processor 802, a memory 804 (this may be optional and in some cases the memory may be internal to the processor) and a transceiver circuitry 806.
  • the processor may execute instructions, e.
  • the memory 804 and/or the transceiver circuitry 806 may be partially or completely contained within the processor 802 (e.g., same semiconductor package).
  • the following solutions may be preferably implemented by some embodiments. [00111] 1.
  • a method of digital communication comprising: receiving (902) a signal over a communication channel; determining (904) an estimate of the communication channel from one or more pilot symbols in the signal transmission, wherein the one or more pilot symbols are assigned along a delay-Doppler resource grid; equalizing (906) non-pilot symbols in the signal transmission by rotating the estimate of the communication channel according to grid locations of the one or more pilot symbols along the delay-Doppler resource grid at other grid locations; and recovering (908) data bits from the equalized non-pilot symbols.
  • the method 900 may be implemented by a receiver (e.g., 102, 104 or 800).
  • a method of digital communication comprising: generating (1002) a signal comprising one or more pilot symbols and one or more non-pilot symbols having transmission resources assigned along a delay-Doppler resource grid; and transmitting (1004) the signal over a communication channel; wherein the one or more pilot symbols are configured to enable a determination of an estimate of the transmission channel at a receiver; and wherein the one or more non-pilot symbols are configured to enable recovery of data bits from the one or more non-pilot symbols by rotating the estimate of the channel transmission based on grid locations of the one or more pilot symbols along the delay-Doppler resource grid at other grid locations.
  • the method 900 may be implemented by a device that transmits signals (e.g., 102, 104 or 800).
  • a device that transmits signals (e.g., 102, 104 or 800).
  • the one or more pilot symbols are mapped to grid locations ⁇ ⁇ ⁇ , ⁇ ⁇ ⁇ at a transmitter-side and are received at grid locations ⁇ ⁇ ⁇ , ⁇ ⁇ ⁇ at a receiver- values h ⁇ , for ⁇ ⁇ 1,2, ... , ⁇ ; and wherein the rotating the estimate at other grid determining: h ⁇ ⁇ ⁇ , ⁇ ⁇ h ⁇ ⁇ ⁇ ⁇ , ⁇ , ⁇ , ⁇ , ⁇ , ⁇ , ⁇ w here ⁇ ⁇ ⁇ ⁇ is a location ⁇ ⁇ , ⁇ ⁇ and the grid ⁇ ⁇ dimensions ⁇ ⁇ ⁇ .
  • the receiver- side applies a rotation that is a function of the x- and y- coordinates of the grid location, the x- and y- coordinates of the pilot location, and the height and width dimensions of the grid. [00114] 4.
  • any of solutions 1-3 wherein the signal is mathematically represented as a super-positions of a number of basis signals, represented in time domain as: ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ , ⁇ ⁇ ⁇ where ⁇ ⁇ ⁇ , ⁇ ⁇ are delay- signal is defined as ⁇ ⁇ ⁇ ⁇ , ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ where ⁇ ⁇ ⁇ ⁇ operation, ⁇ ⁇ ⁇ ⁇ ⁇ F ⁇ ⁇ ⁇ ⁇ ⁇ is an inverse Fourier transform of a pulse in a Doppler domain, ⁇ ⁇ ⁇ ⁇ / ⁇ and ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ are delay and Doppler grid resolutions, respectively, and ⁇ is Dirac delta function.
  • any of solutions 1-5 wherein the signal is generated by: encoding the data bits using a forward error correction code, interleaving an output of the forward error correction, mapping an output of the interleaving to the one or more non-pilot symbols, and mapping the one or more non-pilot symbols to the delay-Doppler grid. Additional examples are disclosed in Sections 4, 5, and 6. [00117] 7. The method of solution 6, wherein the signal is generated by performing an orthogonal time frequency space modulation that uses one of (1) a Zak transform, (2) a two- dimensional (2D) transform, or (3) the basis signals. [00118] 8. The method of solution 7, wherein the 2D transform comprises a symplectic Fourier transform.
  • a symplectic transform may be mathematically characterized by a non-singular, skew-symmetric matrix multiplication.
  • the communication channel comprises an underwater acoustic channel.
  • the communication channel comprises an interstellar communication channel.
  • the communication channel comprises an aerial-to-ground, a ground-to-aerial or an aerial-to-aerial communication channel.
  • the signal may be transmitted at a radio frequency in the fractional tera Hertz to multiples of tera Hertz range.
  • 13 The method of any of solutions 1-12, wherein the signal comprises multiple orthogonal time frequency space frames, each occupying a corresponding time window.
  • 14 The method of solution 13, wherein the time windows are overlapping with other neighboring time windows.
  • 15. The method of solution 14, wherein the time windows are non-overlapping.
  • 16. The method of solution 15, wherein at least some the time windows comprise intervening synchronization signals (SS). 165524628.2 PCT Patent Application 119314.8090.WO00 [00127] 17.
  • SS intervening synchronization signals
  • [00128] 18. The method of solution 16, wherein SS are partially overlapping with neighboring time windows. [00129] 19. The method of any of solutions 16-18, wherein the SS are based on a synchronization sequence. [00130] 20. The method of solution 19, wherein the synchronization sequence comprises a Zadoff-Chu sequence, a pseudo-random sequence, an m-sequence or a Gold code sequence. [00131] 21. The method of any of solutions 19-20, wherein the synchronization sequence uniquely identifies a transmitter that generated the signal. [00132] 22. The method of any of solutions 16-21, wherein the SS is inserted after applying a delay pulse during generation of the signal. [00133] 23.
  • the method of solution 24, wherein the configuration comprises one or more of an orthogonal time frequency space parameter, a power parameter, a medium access control (MAC) layer parameter, a radio resource control (RRC) layer parameter or a physical (PHY) layer parameter.
  • the receiver may identify the SS portion(s) of the signal.
  • the receiver may use blind decoding or autocorrelation based decoding for receiving the SS. Based on the SS portions, the receiver may obtain timing information for OTFS frames. Using the timing information, the receiver may decode the OTFS frame according to a technique disclosed herein. As a result of the decoding, the receiver may extract source bits that were transmitted over the signal that was received. [00137] Furthermore, the receiver may use the received SS to determined configuration parameters of the transmitter, as described herein. In some embodiments, the SS itself may include a configuration parameter that provides a configuration of how SS are interspersed among OTFS frames. [00138] Additional examples of solutions 13-25 are disclosed throughout the present document, including, e.g., section 8.
  • a receiver uses rotated versions of the channel estimation performed at pilot locations to obtain an estimate of the communication channel.
  • the disclosed techniques are flexible and may be used in many different communication scenarios such as radio access networks (RANs) for mobile device communication in various frequency bands in the mega, giga or tera hertz ranges.
  • RANs radio access networks
  • the disclosed techniques may be used in a fixed wireless access scenario in which a base station and/or user devices may be located at relatively stationary locations.
  • Other application scenarios include use of the disclosed techniques using non-terrestrial equipment such as satellites, airborne devices such as airplanes, balloons, drones, etc.
  • the communication channel in such cases may comprise aerial-to-ground, ground-to-aerial or ariel- to-ariel communication, underwater acoustic wave communication deep space communication and so on.
  • the disclosed and other embodiments, modules and the functional operations described in this document can be implemented in digital electronic circuitry, or in computer software, firmware, or hardware, including the structures disclosed in this document and their structural equivalents, or in combinations of one or more of them.
  • the disclosed and other embodiments can be implemented as one or more computer program products, i.e., one or more modules of computer program instructions encoded on a computer readable medium for execution by, or to control the operation of, data processing apparatus.
  • the computer readable medium can be a machine-readable storage device, a machine-readable storage substrate, a memory device, a composition of matter effecting a machine-readable propagated signal, or a combination of one or more them.
  • data processing apparatus encompasses all apparatus, devices, and machines for processing data, including by way of example a programmable processor, a 165524628.2 PCT Patent Application 119314.8090.WO00 computer, or multiple processors or computers.
  • the apparatus can include, in addition to hardware, code that creates an execution environment for the computer program in question, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of them.
  • a propagated signal is an artificially generated signal, e.g., a machine-generated electrical, optical, or electromagnetic signal, that is generated to encode information for transmission to suitable receiver apparatus.
  • a computer program also known as a program, software, software application, script, or code
  • a computer program does not necessarily correspond to a file in a file system.
  • a program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code).
  • a computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network.
  • Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer.
  • a processor will receive instructions and data from a read -only memory or a random access memory or both.
  • the essential elements of a computer are a processor for performing instructions and one or more memory devices for storing instructions and data.
  • a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto optical disks, or optical disks.
  • mass storage devices for storing data
  • a computer need not have such devices.
  • Computer readable media suitable for storing computer program instructions and data include all forms of non-volatile memory, media and memory devices, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and 165524628.2 PCT Patent Application 119314.8090.WO00 flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto optical disks; and CD ROM and DVD-ROM disks.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Discrete Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Power Engineering (AREA)
  • Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
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Abstract

L'invention concerne des procédés et des systèmes de communication d'espace temps-fréquence orthogonal (OTFS) à l'aide de signaux de base prédéfinis. Un exemple de procédé de communication numérique consiste à recevoir un signal sur un canal de communication, à déterminer une estimation du canal de communication à partir d'un ou de plusieurs symboles pilotes dans l'émission de signal. Le ou les symboles pilotes sont attribués le long d'une grille de ressources Doppler à retard. Le procédé consiste en outre à égaliser des symboles non pilotes dans l'émission de signal par rotation de l'estimation du canal de communication en fonction d'emplacements de grille du ou des symboles pilotes le long de la grille de ressources Doppler à retard à d'autres emplacements de grille, et à récupérer des bits de données à partir des symboles non pilotes égalisés.
EP24764679.7A 2023-03-01 2024-03-01 Communication de signal d'espace temps-fréquence orthogonal à l'aide de signaux de base prédéfinis Pending EP4674093A1 (fr)

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US9369328B2 (en) * 2014-03-10 2016-06-14 New York University System and method for providing channel equalization in orthogonal frequency division multiplexing (OFDM) wireless systems
WO2019113046A1 (fr) * 2017-12-04 2019-06-13 Cohere Technologies, Inc. Mise en oeuvre d'une modulation temporelle, fréquentielle et spatiale orthogonale pour des communications sans fil
US11632270B2 (en) * 2018-02-08 2023-04-18 Cohere Technologies, Inc. Aspects of channel estimation for orthogonal time frequency space modulation for wireless communications
US11252754B2 (en) * 2019-01-09 2022-02-15 Ofinno, Llc Configured grant for unlicensed cells
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