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WO2024231961A1 - Génération de formes d'onde de multiplexage par répartition en temps fréquence orthogonale (otfdm) avec diversité de retard circulaire dans le domaine fréquentiel - Google Patents

Génération de formes d'onde de multiplexage par répartition en temps fréquence orthogonale (otfdm) avec diversité de retard circulaire dans le domaine fréquentiel Download PDF

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Publication number
WO2024231961A1
WO2024231961A1 PCT/IN2024/050521 IN2024050521W WO2024231961A1 WO 2024231961 A1 WO2024231961 A1 WO 2024231961A1 IN 2024050521 W IN2024050521 W IN 2024050521W WO 2024231961 A1 WO2024231961 A1 WO 2024231961A1
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Prior art keywords
sequence
sequences
otfdm
filter
phase
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PCT/IN2024/050521
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English (en)
Inventor
Koteswara Rao GUDIMITLA
Sibgath Ali Khan MAKANDAR
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Wisig Networks Private Limited
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Publication of WO2024231961A1 publication Critical patent/WO2024231961A1/fr

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    • 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
    • H04L5/0001—Arrangements for dividing the transmission path
    • H04L5/0014—Three-dimensional division
    • H04L5/0023—Time-frequency-space
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/068—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission using space frequency diversity
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/0008—Modulated-carrier systems arrangements for allowing a transmitter or receiver to use more than one type of modulation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/18—Phase-modulated carrier systems, i.e. using phase-shift keying
    • H04L27/20—Modulator circuits; Transmitter circuits
    • H04L27/2003—Modulator circuits; Transmitter circuits for continuous phase modulation
    • H04L27/2007—Modulator circuits; Transmitter circuits for continuous phase modulation in which the phase change within each symbol period is constrained
    • H04L27/2017—Modulator circuits; Transmitter circuits for continuous phase modulation in which the phase change within each symbol period is constrained in which the phase changes are non-linear, e.g. generalized and Gaussian minimum shift keying, tamed frequency modulation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/18—Phase-modulated carrier systems, i.e. using phase-shift keying
    • H04L27/20—Modulator circuits; Transmitter circuits
    • H04L27/2032—Modulator circuits; Transmitter circuits for discrete phase modulation, e.g. in which the phase of the carrier is modulated in a nominally instantaneous manner
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/18—Phase-modulated carrier systems, i.e. using phase-shift keying
    • H04L27/20—Modulator circuits; Transmitter circuits
    • H04L27/2032—Modulator circuits; Transmitter circuits for discrete phase modulation, e.g. in which the phase of the carrier is modulated in a nominally instantaneous manner
    • H04L27/2035—Modulator circuits; Transmitter circuits for discrete phase modulation, e.g. in which the phase of the carrier is modulated in a nominally instantaneous manner using a single or unspecified number of carriers
    • H04L27/2042—Modulator circuits; Transmitter circuits for discrete phase modulation, e.g. in which the phase of the carrier is modulated in a nominally instantaneous manner using a single or unspecified number of carriers with more than two phase states
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/18—Phase-modulated carrier systems, i.e. using phase-shift keying
    • H04L27/20—Modulator circuits; Transmitter circuits
    • H04L27/2032—Modulator circuits; Transmitter circuits for discrete phase modulation, e.g. in which the phase of the carrier is modulated in a nominally instantaneous manner
    • H04L27/2053—Modulator circuits; Transmitter circuits for discrete phase modulation, e.g. in which the phase of the carrier is modulated in a nominally instantaneous manner using more than one carrier, e.g. carriers with different phases
    • H04L27/206—Modulator circuits; Transmitter circuits for discrete phase modulation, e.g. in which the phase of the carrier is modulated in a nominally instantaneous manner using more than one carrier, e.g. carriers with different phases using a pair of orthogonal carriers, e.g. quadrature carriers
    • 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
    • H04L27/2634—Inverse fast Fourier transform [IFFT] or inverse discrete Fourier transform [IDFT] modulators in combination with other circuits for modulation
    • H04L27/2636—Inverse fast Fourier transform [IFFT] or inverse discrete Fourier transform [IDFT] modulators in combination with other circuits for modulation with FFT or DFT modulators, e.g. standard single-carrier frequency-division multiple access [SC-FDMA] transmitter or DFT spread orthogonal frequency division multiplexing [DFT-SOFDM]
    • 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
    • H04L27/2634—Inverse fast Fourier transform [IFFT] or inverse discrete Fourier transform [IDFT] modulators in combination with other circuits for modulation
    • H04L27/26362—Subcarrier weighting equivalent to time domain filtering, e.g. weighting per subcarrier multiplication
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
    • H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
    • 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
    • H04L5/0001—Arrangements for dividing the transmission path
    • H04L5/0028—Variable division
    • 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

  • Embodiments of the present disclosure are related, in general to communication, but exclusively relate to methods for generating and transmitting orthogonal time frequency division multiplexing (OTFDM) waveform with circular delay diversity in frequency domain.
  • OFDM orthogonal time frequency division multiplexing
  • Orthogonal Frequency Division Multiplexing is widely used in telecommunication and Wireless Fidelity (Wi-Fi) systems.
  • OFDM allows resourceful utilization of a bandwidth.
  • OFDM involves creating sub-carriers from a wideband carrier. Each sub-carrier is an orthogonal frequency, and each sub-carrier carriers a sequence of data. The procedure of mapping data sequence to sub-carriers is known as sub-carrier mapping.
  • the use of orthogonal frequencies helps in reducing guard bands, thus utilizing the bandwidth completely. Because of these advantages, OFDM has been used as a basic waveform for downlink in LTE, LTE advanced, and 5G-NR. However, OFDM use multiple sub-carriers, using OFDM for uplink leads to high Peak Power to Average Ratio (PAPR).
  • PAPR Peak Power to Average Ratio
  • DFT-s-OFDM Discrete Fourier Transform (DFT) spread OFDM
  • the DFT-s-OFDM is essentially a single carrier modulation scheme.
  • DFT-s-OFDM has lower PAPR compared to OFDM.
  • DFT-s-OFDM has similar robustness to the frequency selective fading as OFDM as cyclic prefix is introduced to reduce Inter Symbol Interference (ISI) .
  • a DFT-s-OFDM symbol comprises a data sequence or a pilot sequence (reference sequence).
  • the reference sequence is necessary for enabling channel equalization.
  • the data sequence and the reference sequence are time multiplexed and are sent as independent symbols, i.e., in one symbol data sequence is transmitted and, in another symbol, the reference sequence is transmitted. Hence, in every symbol reference signal may be present.
  • mm wave systems there is a need to track the phase variation caused by Oscillator drift within/on each OFDM symbol.
  • uplink transmitter employs DFT-S-OFDM there is need for a provision to enable phase tracking within one OFDM symbol or across OFDM symbols.
  • 3GPP (3rd Generation Partnership Project) has developed 5G-NR standards to support use cases like eMBB, URLLC, MMTC. It has been agreed to use CP-OFDM waveform and DFT-s-OFDM waveform for uplink transmission in 5G-NR.
  • CP-OFDM is mainly used for higher data rates, while, because of its low PAPR and high-power efficiency, DFT-s-OFDM is used to serve the cell edge UEs.
  • Current 5G standards uses slot structure, where user data is transmitted in series of OFDM symbols.
  • a typical slot structure comprises of one or more data symbols and one or more reference symbols.
  • 6G Mobile Communication System requires a method of information transmission and that offers extremely low latency, very high data rate, and very high-power efficiency.
  • DFT-S-OFDM waveform which is power efficient and supports high data rates is well suitable for this purpose.
  • information like user data, RS, and control information
  • conventional DFT-S-OFDM requires at least one data symbol and at least one reference symbol (RS).
  • the RS is required for the purpose of estimating the channel state information (CSI) and subsequent equalization of data symbol.
  • the current two-symbol structure in 5G-NR not only doubles the latency (compared to single symbol case), but also has a higher RS overhead i.e., 50%.
  • RS overhead i.e. 50%.
  • control information requires appropriate spreading methods of control/data /RS for at least one-shot transmission waveform with high-power efficiency.
  • a method for transmitting a plurality of OTFDM waveforms with circular transmit diversity comprising generating, by a communication system, at least one data sequence and at least one reference sequence (RS). Also, the method comprising time-multiplexing the at least one data sequence with the at least one RS, to generate a multiplexed sequence, and transforming the multiplexed sequence using a Discrete Fourier Transform (DFT) to generate a transformed sequence. Further, the method comprising obtaining a plurality of precoded sequences from the transformed sequence, wherein each of the plurality of precoded sequences is generated by applying a distinct frequency domain phase rotation vector on the transformed sequence.
  • RS reference sequence
  • DFT Discrete Fourier Transform
  • the method comprising mapping, by the communication system, each of the plurality of precoded sequences to a corresponding antenna port of the communication system to obtain a plurality of mapped sequences. Thereafter, the method comprises generating an OTFDM waveform corresponding to each antenna port using the associated mapped sequence, wherein each of antenna port specific OTFDM waveform is transmitted using the corresponding antenna port.
  • FIG. 1A and IB shows orthogonal time frequency division multiplexing (OTFDM) symbol structures with data and RS;
  • Figures 1C-1D shows an illustration of pre-DFT symbols or multiplexed symbols, in accordance with another embodiment of the present disclosure
  • Figure IE shows an illustration of a pre-DFT or multiplexed symbol with data RS CP, RS, data CP, and data;
  • Figure 2A shows a communication system for generating an orthogonal time frequency division multiplexing (OTFDM) waveform with circular delay diversity in frequency domain, in accordance with an embodiment of the present disclosure
  • Figure 2B shows a block of orthogonal time frequency division multiplexing (OTFDM) symbol generation unit, in accordance with an embodiment of the present disclosure
  • FIG. 2C shows a block diagram illustration of the processing unit of the OTFDM symbol generation unit, in accordance with another embodiment of the present disclosure
  • FIG. 2D shows a block diagram illustration of the processing unit of the OTFDM symbol generation unit, in accordance with another embodiment of the present disclosure
  • FIG. 3 shows a block of a communication system for generating and transmitting a plurality of orthogonal time frequency division multiplexing (OTFDM) waveforms, in accordance with some embodiments of the present disclosure
  • Figure 4 shows a block of a communication system for generating OTFDM waveforms with circular delay diversity in frequency domain, in an embodiment of the present disclosure
  • Figures 5A-5C show examples illustrating generation of a plurality of precoded sequences from a transformed sequence for transmission on the associated antennas, in accordance with an embodiment of the present disclosure
  • FIGS 6A-6B shows an illustration of Orthogonal Time Frequency Division Multiplexing (OTFDM) symbol structures with data and RS;
  • OTFDM Orthogonal Time Frequency Division Multiplexing
  • Figure 7A shows a block of a communication system for generating OTFDM waveform with circular delay diversity using STBC, in accordance with an embodiment of the present disclosure
  • Figure 7B shows a block diagram of an OTFDM symbol generation unit 700, in accordance with some embodiments of the present disclosure.
  • Figure 8 shows a block diagram of receiver, in accordance with an embodiment of the present disclosure.
  • Embodiments of the present disclosure relate to generate at least an orthogonal time frequency division multiplexing (OTFDM) waveform using at least one of an input pre- DFT/multiplexed symbol.
  • the at least one pre-DFT/multiplexed symbol is DFT precoded and applied with antenna specific weights to generate one or more precoded sequences.
  • the present disclosure a method for generating a waveform is disclosed. The method comprising generating at least one data sequence or at least one reference sequence (RS). Also, the method comprises time-multiplexing the data sequence with the RS to generate a multiplexed sequence. The time multiplexed sequence is referred as a pre-DFT symbol.
  • the multiplexed sequence also includes at least one of RS cyclic prefix (CP), RS cyclic suffix/ post fix (CS), data CP and optional phase tracking reference signal (PT-RS).
  • CP RS cyclic prefix
  • CS RS cyclic suffix/ post fix
  • PT-RS phase tracking reference signal
  • Figures 1A and IB shows orthogonal time frequency division multiplexing (OTFDM) symbol structures with data and RS.
  • Figure 1A shows an illustration of a symbol with RS pre-fix, RS, RS post-fix and data.
  • Figure IB shows an illustration of a symbol with data CP, data, RS pre-fix, RS, and data.
  • the one OTFDM symbol length is M, comprising of data and RS.
  • the data may optionally include PT-RS for phase compensation at the receiver.
  • Figures 1C-1D shows an illustration of pre-DFT symbols or multiplexed symbols, in accordance with another embodiment of the present disclosure.
  • Figure IE shows an illustration of a pre-DFT or multiplexed symbol with data RS CP, RS, data CP, and data.
  • FIG. 2A shows a communication system for generating an orthogonal time frequency division multiplexing (OTFDM) waveform with circular delay diversity in frequency domain, in accordance with an embodiment of the present disclosure.
  • the communication system is referred to as a transmitter or OTFDM transmitter or a base station (BS).
  • the communication system is a user equipment (UE).
  • UE user equipment
  • the communication system comprises a multiplexing unit 202, a Discrete Fourier Transform (DFT) unit 204, a phase rotation unit 206, a port mapping unit 208, an OTFDM symbol generation unit 210, and a plurality of antennas (212A, 212B, . . . 212Nt).
  • the multiplexing unit 202 is also referred as time multiplexing unit or pre-DFT multiplexing unit.
  • the DFT unit 204 is also referred to as transform unit.
  • the phase rotation unit 206 is also referred as a frequency domain phase rotation unit or phase rotator or frequency domain rotation unit or precoder.
  • the plurality of antennas (212A, 212B, ... 212Nt) together is represented using 212 or referred to as antennas 212.
  • the communication system comprises a pre-DFT generator or inputs generator to generate at least one data 201 A and at least one RS 20 IB.
  • the at least one data is also referred as at least one data sequence or data.
  • the RS 20 IB is also referred as RS.
  • the at least one data sequence is one of a pi/2 binary phase shift keying (pi/2-BPSK) sequence, a BPSK sequence, a Quadrature Phase Shift Keying (QPSK) sequence, M-ary Quadrature Amplitude Modulation (QAM) sequence, and an M-ary Phase Shift Keying (PSK) sequence.
  • the at least one data sequence comprises at least one of a user data, a control information, system information, and paging messages.
  • the user data, control information, system information, and paging messages is a modulated alphabet or sequences of modulated alphabets.
  • the at least one data sequence is appended with a data cyclic prefix (CP), in an embodiment as shown in Figure IB.
  • the at least one data sequence may comprise a user data and at least one phase tracking reference sequence (PTRS).
  • a spreading operation is performed on the at least one data sequence with a spread code to generate a spread data sequence.
  • the spread data sequence is multiplexed with the at least one RS, in an embodiment of the present disclosure.
  • the at least one RS is one of a pi/2 binary phase shift keying (pi/2 -BPSK) sequence, a BPSK sequence, a Zadoff-Chu (ZC) sequence, a Quadrature Phase Shift Keying (QPSK) sequence, and a M-ary Phase Shift Keying (PSK) sequence.
  • the at least one RS is appended with at least one of a cyclic prefix (CP) and a cyclic suffix (CS). As shown in Figure 1A, the RS is prefixed and post-fixed using a CP or RS CP.
  • the multiplexing unit 202 performs multiplexing of the at least one data sequence 201 A and the at least one RS 201B to generate amultiplexed sequence.
  • the multiplexed sequence is one of the sequences or symbols as shown in the Figures 1A-1E.
  • the multiplexed sequence is also referred to as a pre-DFT symbol or pre-DFT sequence.
  • a spreading operation is performed on the multiplexed sequences with a corresponding spread code to generate a spread multiplexed sequences. Thereafter, the spread multiplexed sequences are transformed using the DFT unit 204
  • the DFT unit 204 transforms the multiplexed sequence, generated by the multiplexing unit 202, using a Discrete Fourier Transform (DFT) to generate a transformed multiplexed sequence.
  • the phase rotation unit 206 applies a distinct frequency domain phase rotation vector on the transformed sequence to obtain a plurality of precoded sequences. In an embodiment, the number of times the phase rotation vector is applied on the transformed multiplexed sequence is same as the number of antennas (Nt). Each of the frequency domain phase rotation vector is distinct and is generated using a complex exponential sequence with antenna port specific phasor sequence.
  • the frequency domain phase rotation vector is a phase ramp sequence.
  • the phase ramp sequence vector s phase varies across a plurality of subcarriers, the phase ramp sequence is generated using an antenna specific cyclic shift index.
  • the frequency domain phase rotation vector is a phase ramp sequence in an embodiment.
  • the phase ramp sequence is constant within a physical resource group (PRG) and varies across other PRGs, wherein the phase ramp sequence is generated using an antenna specific cyclic shift index.
  • PRG physical resource group
  • Each of the PRGs comprises a predefined number of subcarriers, said predefined number is an integer. In an embodiment, the predefined number is 6 or multiples of 6.
  • the frequency domain phase rotation vector is a predetermined precoder.
  • the phase and amplitude of the predetermined precoder varies across at least one of subcarriers and PRGs.
  • the frequency domain phase rotation vector for a specific antenna port is same for a predetermine time period or predetermine number of time units.
  • the predetermined umber of time units is referred to as radio frames.
  • the frequency domain phase rotation vector is indicated by a receiver to the communication system.
  • the receiver is a user equipment (UE).
  • the UE provides a feedback of W i.e. frequency domain phase rotation vector to the base station which will be applied by the base station on the transmit data corresponding to that particular UE to generate a plurality of precoded sequences, which is referred as closed loop precoding.
  • the receiver may feedback the index of the frequency domain phase rotation vectors that are defined a priory at the transmitter and receiver.
  • the frequency domain phase rotation vectors are obtained from the DFT weights.
  • the communication system may apply a frequency domain phase rotation vector on the transmit data without any feedback from the receiver (UE).
  • the frequency domain phase rotation vectors may be obtained from a set of predefined vectors.
  • the predefined vector may be obtained from DFT weights.
  • the port mapping unit 208 is also referred to as antenna port mapping unit or antenna port mapper or mapping unit.
  • the mapping unit 208 performs port mapping of each of the plurality of precoded sequences to a corresponding antenna port of the communication system to obtain a plurality of mapped sequences.
  • the OTFDM symbol generation unit 210 generates an OTFDM waveform corresponding to each antenna port using the associated mapped sequence. Each plurality of mapped sequences is fed to the OTFDM symbol generation unit 210 to generate a plurality of OTFDM waveforms specific to a particular antenna. Each of antenna port specific OTFDM waveform is transmitted using the corresponding antenna port.
  • the communication unit achieves a circular delay diversity by transmitting the plurality of OTFDM waveforms from a plurality of antenna ports with different phase rotations.
  • FIG. 2B shows a block of orthogonal time frequency division multiplexing (OTFDM) symbol generation unit, in accordance with an embodiment of the present disclosure.
  • the OTFDM symbol generation unit 210 is also referred to as OTFDM generation unit 210 or an excess bandwidth (BW) DFT-s-OFDM symbol generation unit or OTFDM generator.
  • the OTFDM symbol generation unit 210 comprises an excess BW addition unit 222, a spectrum shaping unit 224, a sub-carrier mapping unit 226, an inverse Fast Fourier transform (IFFT) unit 228 and a processing unit 230.
  • IFFT inverse Fast Fourier transform
  • the excess BW extension unit 222 performs padding operation by prefixing each of the plurality of mapped sequences with a first predefined number (Nl) of subcarriers and postfixing the transformed multiplexed sequence with a second predefined number (N2) of subcarriers to obtain corresponding plurality of extended bandwidth mapped sequences.
  • Nl predefined number
  • N2 second predefined number
  • the value of the Nl is at least zero
  • the values of Nl and N2 may be same or different.
  • the value of Nl and N2 may depend on the excess power that is sent by the transmitter.
  • the spectrum shaping unit 224 also referred as a shaping unit or a filter, performs shaping of the plurality of extended bandwidth mapped sequences to obtain a plurality of shaped sequences or shaped sequences.
  • the filter used for the shaping operation on the extended bandwidth transformed multiplexed sequence is one of a Nyquist filter, square root raised cosine filter, a raised cosine filter, a hamming filter, a Hanning filter, a Kaiser filter, an oversampled GMSK filter and any filter that satisfies predefined spectrum characteristics.
  • the distributed subcarrier mapping includes insertion of zeros in to the extended bandwidth transformed multiplexed sequence.
  • the Inverse Fast Fourier Transform (IFFT) unit 228 performing IFFT on each of the plurality of shaped sequences to produce a plurality of time domain sequences.
  • IFFT Inverse Fast Fourier Transform
  • the processing unit 230 processes the plurality of time domain sequences to generate a plurality of OTFDM waveforms, also referred to as a filtered-extended bandwidth DFT-s- OFDM waveform.
  • FIG. 2C shows a block diagram illustration of the processing unit of the OTFDM symbol generation unit, in accordance with another embodiment of the present disclosure.
  • the processing unit 230 comprises a cyclic prefix (CP) addition unit 242, a weighted with overlap and add operation (WOLA) unit 246, bandwidth parts (BWP) rotation unit 248, a radio frequency (RF) conversion unit 250 and a digital to analog converter (DAC) 252.
  • CP cyclic prefix
  • WOLA weighted with overlap and add operation
  • BWP bandwidth parts
  • RF radio frequency
  • DAC digital to analog converter
  • the processing unit 230 processes an input 240 i.e. the plurality of time domain sequences to generate a plurality of OTFDM waveforms or also referred to as output 254.
  • the processing unit 230 processes each of the plurality of time domain sequences by performing at least one of a symbol specific phase compensation, an addition of symbol cyclic prefix or addition of symbol cyclic suffix using the CP addition unit 242, windowing or weighted with overlap and add operation (WOLA) operation using the WOLA unit 246, a BWP rotation using the BWP rotation unit 248, an additional time domain filtering, sampling rate conversion using RF up conversion unit 250 to match DAC rate, frequency shifting on the time domain waveform and digital to analog conversion using DAC 252, to generate an OTFDM waveform.
  • WOLA overlap and add operation
  • the OTFDM symbol generation unit generates a plurality of OTFDM waveforms corresponding to the plurality of time domain sequences. Thereafter, the communication system transmits an OTFDM waveform by mapping the generated OTFDM symbols to the corresponding antenna ports of the communication system.
  • the generated OTFDM waveform which eventually offers low PAPR.
  • FIG. 2D shows a block diagram illustration of the processing unit of the OTFDM symbol generation unit, in accordance with another embodiment of the present disclosure.
  • the processing unit 230A comprises a weighted with overlap and add operation (WOLA) unit 246, bandwidth parts (BWP) rotation unit 248, a radio frequency (RF) conversion unit 250 and a digital to analog converter (DAC) 252.
  • WOLA weighted with overlap and add operation
  • BWP bandwidth parts
  • RF radio frequency
  • DAC digital to analog converter
  • the processing unit 230A processes each of the plurality of time domain sequences, also referred to as an input, 240 to generate a plurality of OTFDM waveform 254.
  • the time domain sequence is obtained for the IFFT unit, which is configured in the OTFDM symbol generation unit, in an embodiment.
  • the input to OTFDM symbol generation is a plurality of time domain sequences as shown in Figures 1C-1D.
  • the processing unit processes each of the plurality of mapped sequences by performing at least one of a windowing or weighted with overlap and add operation (WOLA) operation using the WOLA unit 246, a BWP rotation using the BWP rotation unit 248, an additional time domain filtering, sampling rate conversion using RF up conversion unit 250 to match DAC rate, frequency shifting on the time domain waveform and digital to analog conversion using DAC 252, to generate the OTFDM waveform.
  • the OTFDM symbol generation unit generates a plurality of OTFDM waveforms corresponding to the plurality of time domain sequences. Thereafter, the communication system transmits an OTFDM waveform by mapping the generated OTFDM symbols to the corresponding antenna ports of the communication system.
  • FIG. 3 shows a block of a communication system for generating and transmitting a plurality of orthogonal time frequency division multiplexing (OTFDM) waveforms, in accordance with some embodiments of the present disclosure.
  • the communication system 300 is referred to as a transmitter or OTFDM transmitter or a base station (BS).
  • the communication system is a user equipment (UE).
  • the communication system 300 performs transmission of the OTFDM waveform with circular delay diversity in frequency domain.
  • the communication system 300 comprises a Discrete Fourier Transform (DFT) unit 304, a phase rotation unit 308, a spectrum shaping unit 310, an inverse Fast Fourier Transform (IFFT) unit 312, and a plurality of antennas (314A, 314B, ..., 314Nt).
  • DFT Discrete Fourier Transform
  • phase rotation unit 308 a phase rotation unit 308
  • spectrum shaping unit 310 a spectrum shaping unit 310
  • IFFT inverse Fast Fourier Transform
  • 314A, 314B, ..., 314Nt a plurality of antennas
  • the communication system 300 includes an input pre- DFT/multiplexed sequence generator also referred as input pre-DFT generation unit or input generator.
  • the input generator generates at least one data sequence and at least one RS.
  • the at least one data sequence is multiplexed with the at least one RS to generate input pre-DFT symbol to the communication system.
  • the pre-DFT sequence or multiplexed sequence is transformed using the DFT unit to generate a transformed sequence, also referred to as transformed pre-DFT sequence or symbol.
  • the at least one pre-DFT symbol is one of the multiplexed symbols shown in Figures 1A, IB, 1C, ID and IE.
  • the transformed sequence is directly fed to the excess BW spectrum shaping unit, along J27T Dk with the precoded sequences of the transformed sequence using e M , where i value ranges from 1 to number of antennas.
  • D is a variable which is a function of the plurality of antennas. Also, the D is antenna specific variable.
  • the transformed sequence is directly fed to the excess BW spectrum and shaping unit, along with the precoded sequence of the transformed sequence, also referred to as phase shifted symbols or plurality of precoded sequences.
  • a spectrum extension is performed on the shifted phase symbols using spectrum shaping unit 310, such that last d/2 samples of the phase shifted symbol are copied and placed at the beginning of the symbol as pre-fix and then the initial d/2 samples of the phase shifted symbol are copied and placed at the end of the symbol as post-fix, where d is the spectrum extension factor.
  • the precoded sequences are mapped to antenna port to obtain plurality of mapped sequences.
  • the spectrum shaping unit 310 also referred as an excess BW spectrum shaping unit or shaping unit or a filter, performs shaping on the plurality of mapped sequences to generate a plurality of shaped excess BW transformed sequences or also referred to as shaped sequences.
  • the excess BW spectrum shaping unit or the filter used for the shaping operation on the transformed sequences is one of a Nyquist filter, square root raised cosine filter, a raised cosine filter, a hamming filter, a Hanning filter, a Kaiser filter, an oversampled GMSK filter and any filter that satisfies predefined spectrum characteristics.
  • the IFFT unit 312 performs inverse FFT on the shaped sequences to generate a plurality of time domain sequences specific to the each of the corresponding plurality of antennas.
  • Each of the symbol sequence is sent to one of the associated plurality of antennas (314A, 314B, . . . , 314Nt) based on the value variable D, for transmission.
  • Figure 4 shows a block of a communication system for generating OTFDM waveforms with circular delay diversity in frequency domain, in an embodiment of the present disclosure.
  • the communication system 400 is also referred as a transmitter or a base station (BS).
  • the communication system is a user equipment (UE).
  • the communication system as shown in Figure 4 comprises an input generation unit or pre-DFT/multiplexed symbol generation unit, a DFT unit 404, a phase rotation unit with a variable W for each PRB unit 408, an excess BW spectrum shaping unit 410, an IFFT unit 412 and a plurality of antennas (414A, 414B, . . . , 414Nt) .
  • the input pre-DFT generator also referred as input pre-DFT generation unit or input generator, generates a plurality of pre-DFT symbols.
  • the symbols are as shown in Figures 1A-1E.
  • the input pre DFT symbol 401 is fed to the DFT unit 404 to generate transformed sequence.
  • the phase rotation unit with a variable W for each PRB unit 408 performs phase rotation on the transformed sequence to generate one or more rotated sequences.
  • the phase rotation depends on a variable W which is constant for each PRB unit, where W is a column vector with elements being phase rotations.
  • W is fixed in time for several frames but changes every PRG, where in PRG is a group of subcarriers or Physical Resource Blocks (PRBs), the group can be 1, 2, 3, 4 or multiples of 6 subcarriers or multiples of PRBs, each resource block contains predefined set of subcarriers, for example multiples of 6.
  • PRG is a group of subcarriers or Physical Resource Blocks (PRBs)
  • the group can be 1, 2, 3, 4 or multiples of 6 subcarriers or multiples of PRBs
  • each resource block contains predefined set of subcarriers, for example multiples of 6.
  • the excess BW spectrum shaping unit 410 also referred as a shaping unit or a filter, performs shaping on the one or more rotated sequences to generate a plurality of shaped excess BW transformed sequences or also referred to as shaped sequences.
  • the excess BW spectrum shaping unit or the filter used for the shaping operation on the transformed sequences is one of a Nyquist filter, square root raised cosine filter, a raised cosine filter, a hamming filter, a Hanning filter, a Kaiser filter, an oversampled GMSK filter and any filter that satisfies predefined spectrum characteristics.
  • the IFFT unit 412 performs inverse FFT on the shaped sequences to generate a plurality of time domain sequences specific to the each of the corresponding plurality of antennas.
  • Each of the symbol sequence is sent to a corresponding antenna (414A, 414B, ..., 414Nt) based on the value variable D, for transmission.
  • Figures 5A-5C show examples illustrating generation of a plurality of precoded sequences from a transformed sequence for transmission on the associated antennas, in accordance with an embodiment of the present disclosure.
  • Figure 5A shows an illustration of generating a plurality of precoded sequences from the transformed sequence, each of the generated preceded sequence is associated with one of the Nt antennas.
  • the antennas are also referred to as transmit antennas.
  • Each antenna is having a corresponding transformed sequence which is obtained by shifting the previous transformed sequence in frequency domain, for all the antennas i.e. each sample of the previous transformed sequence is multiplied with corresponding weights associated with the antenna.
  • the associated sequence- N t or precoded sequence- N t is obtained by multiplying each element of [xo, xi, X2...XM-1] with the corresponding weights of [1, e .
  • Figure 5B shows an illustration of generating a plurality of precoded sequences from the transformed sequence in accordance with another embodiment of the present disclosure, each of the generated preceded sequence is associated with one of the Nt antennas. As shown in Figure 5B, there are Nt precoded sequences corresponding to Nt antennas which are obtained by circularly left shifting the base sequence in frequency domain.
  • each sample of the transformed sequence is multiplied with a corresponding weights associated with the antenna.
  • the associated sequence-3 or precoded sequence-3 is obtained by multiplying each element of [xo, xi, X2...XM-1] with the corresponding weights of [1, e M , e M ,
  • the associated sequence- N t or precoded sequence- Nt is obtained by multiplying each element of [xo, xi, X2...XM-1] with the corresponding weights of [1, e M , e M , e M
  • FIG. 5C shows an illustration of generating a plurality of precoded sequences from the transformed sequence, in accordance with yet another embodiment of the present disclosure.
  • the transformed sequence is grouped into a plurality of groups, where each group comprises a set of samples/ elements.
  • each group is referred as a physical resource group (PRG).
  • PRG physical resource group
  • Each of the plurality of groups is applied with a corresponding weight associated with one of the plurality of antenna, for transmission. For example, for antenna-1 (ANT-1), the first group of precoded sequences jOl j02 is multiplied with ne , the second group is multiplied with ne and this multiplication is performed till the last group, which is associated with the antenna-Nt.
  • ANT-1 antenna-1
  • spectrum extension factor ‘d’ When spectrum extension factor ‘d’ is zero, no spectrum extension is performed, for example modulation schemes like pi/2-BPSK.
  • spectrum shaping can be performed either in time-domain by circular convolving the data-RS multiplexed symbol with impulse response of the spectrum shaping filter or in frequency domain, where the DFT-pre-coded symbol is simply multiplied with the frequency response of the spectrum shaping filter.
  • the spectrum shaping help in reduction of PAPR, which eventually results in better power efficiency.
  • One embodiment of the present disclosure is a receiver.
  • the received signal is first processed with front processing elements like ADC, CP removal and FFT.
  • the allocated sub-carriers are de-mapped in the sub-carrier de-mapper, where M+d allocated sub-carriers are de-mapped from entire FFT output. If spectrum shaping performed at the transmitter is with square root of the frequency response of the spectrum shaping filter and filter is known at the receiver, then de-mapped “M+d” subcarriers are multiplied with the same filter used at the transmitter before further processing. This helps in maximizing the receiver SNR. If the filter is not known at the receiver, then the demapped data is processed without any receiver shaping.
  • the filter used at the receiver can be called as subcarrier filters.
  • Each of the subcarrier filters is one of SQRC, RC, Hanning, Hamming, Blackman, or LGMSK pulses, or square root of these pulses.
  • the method includes a base sequence that is obtained by taking a BPSK sequence that goes through pi/2 constellation rotation. Various cyclic shifts of the base sequence may be used as inputs. The base sequences and the number of cyclic shifts that result in low PAPR and low correlation among the base sequences and zero correlation among the cyclic shifts of a base sequence may be obtained through a computer search. The base sequences are optimized such that the generated waveforms have optimized or low PARP. [0089] In an embodiment of the present disclosure, a method for transmitting a plurality of OTFDM waveforms with circular transmit diversity is disclosed. The method comprising generating, by a communication system, at least one data sequence and at least one reference sequence (RS).
  • RS reference sequence
  • the method comprising time-multiplexing the at least one data sequence with the at least one RS, to generate a multiplexed sequence, and transforming the multiplexed sequence using a Discrete Fourier Transform (DFT) to generate a transformed sequence. Further, the method comprising obtaining a plurality of precoded sequences from the transformed sequence, wherein each of the plurality of precoded sequences is generated by applying a distinct frequency domain phase rotation vector on the transformed sequence. Furthermore, the method comprising mapping, by the communication system, each of the plurality of precoded sequences to a corresponding antenna port of the communication system to obtain a plurality of mapped sequences. Thereafter, the method comprises generating an OTFDM waveform corresponding to each antenna port using the associated mapped sequence, wherein each of antenna port specific OTFDM waveform is transmitted using the corresponding antenna port.
  • DFT Discrete Fourier Transform
  • Embodiments of the present disclosure relates to a method for generating an Orthogonal Time Frequency Division Multiplexing (OTFDM) waveform using space time block coding (STBC).
  • OTFDM waveform enables 6G Mobile communication system a method of information transmission and that offers extremely low latency, very high data rate, and very high-power efficiency.
  • OTFDM with STBC encoding provides transmission diversity in conditions where one antenna signal has low received power and other antenna higher power.
  • the OTFDM-STBC receiver provides the diversity benefit.
  • the method of generating OTFDM waveform comprises generating at least one data sequence or at least one reference sequence (RS). Also, the method comprises time-multiplexing data sequences SI, S2 with a first RS (RSI) along with cyclic prefix (CP) of the first RS to generate a first multiplexed sequence. Also, time-multiplexing complex conjugate and time reversed data sequence with a negative symbol S2 i.e. -S2*, complex conjugate and time reversed data sequence SI* with a second RS (RS2) along with cyclic prefix (CP) of the second RS to generate a second multiplexed sequence.
  • RSI first RS
  • CP cyclic prefix
  • the first RS and second RS are orthogonal to each other.
  • the data sequence (SI, S2) is a sequence of real/complex modulation alphabets.
  • the first multiplexed sequence and second multiplexed sequence are collectively referred as multiplexed sequences or time multiplexed sequences.
  • the multiplexed sequences are referred as a pre-DFT symbol.
  • the first multiplexed sequence and second multiplexed sequence are as shown in Figures 6A and 6B respectively.
  • Figures 6A-6B shows an illustration of Orthogonal Time Frequency Division Multiplexing (OTFDM) symbol structures with data and RS.
  • Figure 6A shows an illustration of an OTFDM symbol with RSI pre-fix, RSI, data SI and data S2.
  • Figure 6B shows an illustration of an OTFDM symbol with RS2 pre-fix, RS2, complex conjugatetime reversed data with a negative symbol S2 i.e. -S2*, and complex conjugate-time reversed data S 1.
  • the data sequence may optionally include PT-RS for phase compensation at the receiver.
  • FIG. 7A shows a block of a communication system for generating OTFDM waveform with circular delay diversity using STBC, in accordance with an embodiment of the present disclosure.
  • the communication system is also referred to as an OTFDM transmitter or transmitter or base station (BS).
  • the communication systems is a user equipment (UE).
  • the transmitter comprises an OTFDM symbol generation unit 700, input pre-DFT generator, and a plurality of antennas.
  • the transmitter comprises two antennas (703A, 703B).
  • the input pre-DFT generator also referred as input pre-DFT generation unit or input generator, generates one or more pre-DFT symbols or multiplexed symbols or symbols.
  • the input to the transmitter are the symbols 701 A, 70 IB as shown in Figures 6A-6B.
  • Each of the symbols, also referred to as multiplexed sequences are processed through the excess bandwidth (BW) symbol generation unit, to generate corresponding excess BW symbols or waveforms specific to a particular antenna.
  • the transmitter comprises two antennas.
  • the waveforms generated are transmitted by the corresponding two antennas i.e. first waveform generated using the symbol of Figure 6A is transmitted by ANT-1 703A and second waveform generated using the symbol of Figure 6B is transmitted by ANT-2 703B.
  • FIG. 7B shows a block diagram of an OTFDM symbol generation unit 700, in accordance with some embodiments of the present disclosure.
  • the OTFDM symbol generation unit 700 also referred to as an extended BW symbol generator, comprises a Discrete Fourier Transform (DFT) unit 708, an excess BW addition unit 710, a spectrum shaping unit 712, a subcarrier mapping unit 714, an IFFT unit 716, a WOLA unit 718, a DAC 720.
  • DFT Discrete Fourier Transform
  • the DFT unit 708 transforms an input 730 i.e. a multiplexed sequence using a Discrete Fourier Transform (DFT) to generate a transformed multiplexed sequence.
  • the input are the symbols as shown in Figures 6A and 6B.
  • each of the data sequences SI and S2 as shown in Figures 6A and 6B will includes a data cyclic prefix (CP).
  • the symbols may include data CP are provided as input 730 to the OTFDM symbol generation unit 700, in an embodiment.
  • the excess BW extension unit 710 performs padding operation on the transformed multiplexed sequence i.e. prefixing the transformed multiplexed sequence with a first predefined number (Nl) of subcarriers and post-fixing the transformed multiplexed sequence with a second predefined number (N2) of subcarriers to obtain an extended bandwidth transformed multiplexed sequence.
  • Nl predefined number
  • N2 second predefined number
  • the value of the Nl is at least zero, and value of the N2 is at least zero.
  • the values of Nl and N2 may be same or different. The value of Nl and N2 may depend on the excess power that is sent by the transmitter.
  • the spectrum shaping unit 712 also referred as a with shaping unit with excess BW unit or excess BW unit shaping unit or shaper or a filter, performs shaping of the extended bandwidth transformed multiplexed sequence to obtain a shaped extended bandwidth transformed multiplexed sequence or shaped sequence.
  • the filter used for the shaping operation on the extended bandwidth transformed multiplexed sequence is one of a Nyquist filter, square root raised cosine filter, a raised cosine filter, a hamming filter, a Hanning filter, a Kaiser filter, an oversampled GMSK filter and any filter that satisfies predefined spectrum characteristics.
  • the sub carrier mapping unit 714 also referred as a mapper or a sub carrier mapper or a mapping unit, performs subcarrier mapping on the shaped extended bandwidth transformed multiplexed sequence or shaped sequence with at least one of localized and distributed subcarriers to generate a mapped extended bandwidth transformed multiplexed sequence.
  • the distributed subcarrier mapping includes insertion of zeros in to the extended bandwidth transformed multiplexed sequence.
  • the IFFT unit 716 performing an Inverse Fast Fourier Transform (IFFT) on the shaped extended bandwidth transformed multiplexed sequence to produce a time domain sequence. Thereafter, the WOLA unit 718 performs weighted with overlap and add operation on the time domain sequence to produce windowed sequence.
  • the DAC 720 generates an analog signal or waveform using the windowed sequence, the generated waveform is transmitted using one or more antennas, configured in the transmitter.
  • the output of the IFFT unit 716 i.e. time domain sequence is padded with CP and processed though WOLA unit 718 and DAC 720 to generate waveform for transmission.
  • the generated waveforms are transmitted using the two antennas, ANT- 1 703A and ANT-2 703B.
  • the transmitter 700 may comprise a processing unit after the subcarrier mapping unit 714.
  • the processing unit processes the time domain sequence to generate the filtered-extended bandwidth DFT-s-OFDM symbol.
  • the processing unit performs an Inverse Fast Fourier Transform (IFFT) on the shaped extended bandwidth transformed multiplexed sequence to produce a time domain sequence and processing the time domain sequence to generate the OTFDM symbol or filtered-extended bandwidth DFT-s-OFDM symbol.
  • IFFT Inverse Fast Fourier Transform
  • the processing of the time domain sequence to generate a OTFDM symbol comprises performing at least one of a symbol specific phase compensation, an addition of symbol cyclic prefix, addition of symbol cyclic suffix, windowing, weighted with overlap and add operation (WOLA), bandwidth parts (BWP) rotation, an additional time domain filtering, sampling rate conversion to match DAC rate, frequency shifting on the time domain waveform and a digital to analog converter (DAC), to generate an OTFDM waveform or filtered-extended bandwidth DFT-s-OFDM symbol for transmission.
  • WOLA overlap and add operation
  • BWP bandwidth parts
  • DAC digital to analog converter
  • FIG. 8 shows a block diagram of receiver, in accordance with an embodiment of the present disclosure.
  • the receiver 800 comprises a Discrete Fourier Transform (DFT) unit 802, a channel estimation unit 804, a space frequency equalizer 806 and an inverse Discrete Fourier Transform (IDFT) unit 808.
  • the channel estimation unit 804 is also referred to as a channel estimator or channel estimation unit on first RS and second RS.
  • the receiver receives an input referred as a received signal 812, which is first processed with front end processing unit comprising ADC and CP removal to produce processed received signal.
  • the DFT unit 802 is a fast Fourier transform (FFT).
  • FFT fast Fourier transform
  • the transformed sequence is de-mapped using allocated sub-carriers using a sub-carrier de-mapper, where M+d allocated sub-carriers are de-mapped from entire FFT output. If spectrum shaping performed at the transmitter is with square root of the frequency response of the spectrum shaping fdter and fdter is known at the receiver, then de-mapped “M+d” subcarriers are multiplied with the same fdter used at the transmitter before further processing. This helps in maximizing the receiver SNR. If the fdter is not known at the receiver, then the de-mapped data is processed without any receiver shaping. The fdter used at the receiver is referred as subcarrier fdter. The subcarrier fdter is one of SQRC, RC, Hanning, Hamming, Blackman, or LGMSK fdters, or square root of these fdters.
  • the channel estimation unit 804 estimates a channel from the de-mapped sequence based on an estimation method.
  • the space frequency equalizer 806 performs equalization on the de-mapped sequence using the estimated channel to obtain an equalized sequence.
  • the IDFT unit 808 performs an ID FT on the equalized sequence to generate a time domain sequence and de-multiplexing the time domain sequence to obtain an output 814 i.e. at least one of a reference sequence (RS) and a data sequence.
  • RS reference sequence

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Abstract

Des modes de réalisation de la présente invention concernent un procédé de génération de formes d'onde de multiplexage par répartition en temps fréquence orthogonale (OTFDM). Le procédé comprend la génération, par un système de communication, d'au moins une séquence de données et d'au moins une séquence de référence (RS). Le procédé comprend également le multiplexage temporel de la ou des séquences de données avec le ou les RS, pour générer une séquence multiplexée, et la transformation de la séquence multiplexée à l'aide d'une DFT pour générer une séquence transformée. En outre, le procédé consiste à obtenir des séquences précodées à partir de la séquence transformée, par application d'un vecteur de rotation de phase de domaine fréquentiel distinct sur la séquence transformée. En outre, la mise en correspondance de chaque séquence précodée avec un port d'antenne correspondant du système de communication pour obtenir une pluralité de séquences mises en correspondance. Ensuite, la génération d'une forme d'onde OTFDM correspondant à chaque port d'antenne à l'aide de la séquence mise en correspondance associée.
PCT/IN2024/050521 2023-05-11 2024-05-11 Génération de formes d'onde de multiplexage par répartition en temps fréquence orthogonale (otfdm) avec diversité de retard circulaire dans le domaine fréquentiel WO2024231961A1 (fr)

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Citations (4)

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Publication number Priority date Publication date Assignee Title
US8773974B2 (en) * 2005-03-30 2014-07-08 Apple Inc. Method and system for combining OFDM and transformed OFDM
US9794039B2 (en) * 2007-04-26 2017-10-17 Lg Electronics Inc. Method of transmitting reference signal in wireless communication system
WO2018231626A1 (fr) * 2017-06-14 2018-12-20 Idac Holdings, Inc. Procédés, appareil, systèmes, architectures et interfaces de transmission d'informations de commande de liaison montante (uci) par l'intermédiaire d'un canal de données partagées de liaison montante
US11349622B2 (en) * 2016-12-02 2022-05-31 Wisig Networks Private Limited Method and a system for transmitting DFT-s-OFDM symbols

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8773974B2 (en) * 2005-03-30 2014-07-08 Apple Inc. Method and system for combining OFDM and transformed OFDM
US9794039B2 (en) * 2007-04-26 2017-10-17 Lg Electronics Inc. Method of transmitting reference signal in wireless communication system
US11349622B2 (en) * 2016-12-02 2022-05-31 Wisig Networks Private Limited Method and a system for transmitting DFT-s-OFDM symbols
WO2018231626A1 (fr) * 2017-06-14 2018-12-20 Idac Holdings, Inc. Procédés, appareil, systèmes, architectures et interfaces de transmission d'informations de commande de liaison montante (uci) par l'intermédiaire d'un canal de données partagées de liaison montante

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