WO2016041463A1 - Signalisation à faible facteur de crête pour un canal de diffusion commun dans des systèmes mimo - Google Patents

Signalisation à faible facteur de crête pour un canal de diffusion commun dans des systèmes mimo Download PDF

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Publication number
WO2016041463A1
WO2016041463A1 PCT/CN2015/089353 CN2015089353W WO2016041463A1 WO 2016041463 A1 WO2016041463 A1 WO 2016041463A1 CN 2015089353 W CN2015089353 W CN 2015089353W WO 2016041463 A1 WO2016041463 A1 WO 2016041463A1
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Prior art keywords
broad
transmitter
signal
sequence
papr
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PCT/CN2015/089353
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English (en)
Inventor
Ming Jia
Jianglei Ma
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Huawei Technologies Co., Ltd.
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Publication date
Priority claimed from US14/490,483 external-priority patent/US9973362B2/en
Application filed by Huawei Technologies Co., Ltd. filed Critical Huawei Technologies Co., Ltd.
Priority to JP2017515158A priority Critical patent/JP2017535996A/ja
Priority to CN201580047003.3A priority patent/CN106716947B/zh
Priority to EP15842853.2A priority patent/EP3186938A4/fr
Publication of WO2016041463A1 publication Critical patent/WO2016041463A1/fr

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    • 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
    • H04B7/0413—MIMO systems
    • H04B7/0456—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
    • H04B7/0482—Adaptive codebooks
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B15/00—Suppression or limitation of noise or 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
    • H04L27/2614—Peak power aspects

Definitions

  • the present disclosure relates generally to wireless communications, and more particularly to low Peak-to-Average-Power-Ratio (PAPR) signaling for common broadcast channels in massive Multiple-Input Multiple-Output (MIMO) systems.
  • PAPR Peak-to-Average-Power-Ratio
  • MIMO Multiple-input multiple-output
  • spectral efficiency e.g., link reliability, etc.
  • spectral efficiency e.g., link reliability
  • MIMO offers significant increases in data throughput and link range without additional bandwidth or increased transmit power.
  • Large scale antenna systems known as Massive MIMO also referred to as very large MIMO, and hyper MIMO
  • use a very large number of service antennas at the base station e.g., hundreds or thousands
  • the number of user equipment serviced e.g., tens or hundreds
  • M-MIMO uses M-MIMO designs to allow for the extensive use of inexpensive low-power components, reduced latency, simplification of the media access control (MAC) layer, and robustness to intentional jamming. Accordingly, techniques for integrating M-MIMO systems into next-generation wireless networks are desired.
  • MAC media access control
  • Power density is a value used to describe how the transmit power in a communications signal is distributed over frequency. It is expressed in terms of power divided by a relatively small unit of bandwidth (e.g. dBW/kHz) and is usually referenced to the input of the antenna.
  • the speed at which digital information flows is the data rate of the signal. In general, as the data rate of a signal increases, so does the range of frequencies occupied by that signal. Assuming total power in the signal is constant; increasing the data rate will spread power over a wider range of frequencies and decrease power density. The inverse is also true.
  • LTE-Advanced networks should target a downlink (DL) peak data rate of 1 Gbps.
  • DL downlink
  • LTE-Advanced introduces “multicarrier” which refers to the aggregation of multiple carriers to increase data rates.
  • multi-carrier signals exhibit high peak-to-average-power-ratio (PAPR) and require expensive highly linear power amplifiers. Linear power amplifiers are also very power inefficient.
  • PAPR peak-to-average-power-ratio
  • PAPR reduction includes peak windowing, scaling, and clipping but such techniques induce interference and introduce distortion in an OFDM signal and require the signal to undergo filtering to reduce the interference and distortion to an acceptable level.
  • Block coding is another technique to reduce PAPR.
  • LTE Long Term Evolution
  • 3GPP Third Generation Partnership Project
  • PSS Primary Synchronization Signal
  • SSS Secondary Synchronization Signal
  • the PSS and SSS signals are transmitted twice per ten millisecond radio frame and are fixed at the central sixty-two subcarriers of the channel. The detection of these signals allows the UE to complete time and frequency synchronization and to acquire useful system parameters such as cell identity, cyclic prefix length, and access mode (FDD/TDD) .
  • FDD/TDD access mode
  • the UE also decodes the Physical Broadcast Control Channel (PBCH) common broadcast signal from which it obtains important system information.
  • PBCH Physical Broadcast Control Channel
  • the PBCH is transmitted using a Space Frequency Block Code (SFBC) , which repeats every forty milliseconds, and carries what is termed as the Master Information Block (MIB) message.
  • SFBC Space Frequency Block Code
  • MIB Master Information Block
  • the MIB message on the PBCH is mapped onto the central seventy-two subcarriers of the channel.
  • the Physical Downlink Control Channel (PDCCH) common broadcast signal carries the resource assignment for UEs which are contained in a Downlink Control Information (DCI) message.
  • DCI Downlink Control Information
  • SI-RNTI System Information Radio Network Temporary Identifier
  • SIBs broadcast System Information Blocks
  • the Physical Downlink Shared Channel (PDSCH) common broadcast signal is the main data bearing channel which is allocated to users on a dynamic and opportunistic basis.
  • the PDSCH carries data in so-called Transport Blocks (TB) .
  • Transport Blocks TB
  • Phase rotation techniques search the optimum set of phase factors. However, the search complexity of the optimum phase increases exponentially with the number of sub-blocks, and the phase factors in the receiver must be known.
  • An active constellation extension (ACE) technique can reduce PAPR by extending a constellation point toward the outside of the original constellation. Compared with the previously mentioned techniques, ACE induces no BER degradation and requires no special processing. However, it introduces a power increase and high complexity because of an iterative constellation extension process.
  • PAPR Peak-to-Average-Power-Ratio
  • a method of transmitting a broad-beam signal with a Multiple-Input Multiple-Output (MIMO) transmitter to User Equipment (UE) comprises the steps of modulating the broad-beam signal with a low Peak-to-Average-Power Ratio, PAPR, sequence; and transmitting the modulated broad-beam signal over a frequency band narrower than an available bandwidth.
  • MIMO Multiple-Input Multiple-Output
  • the low PAPR sequence is one of a Zadoff-Chu sequence and a Golay complementary sequence.
  • the broad-beam signal is a Primary Synchronization Signal and optionally the available bandwidth comprises a plurality of subcarriers and the frequency band is defined as central 62 subcarriers of the available bandwidth.
  • the broad-beam signal is a Secondary Synchronization Signal, and optionally the available bandwidth comprises a plurality of subcarriers and the frequency band is defined as central 62 subcarriers of the available bandwidth.
  • the method further includes introducing transmit diversity through vector hopping without affecting the low PAPR sequence, and optionally the vector hopping weights two antennas alternating between [+1, +1] T and [+1, -1] T from subframe to subframe.
  • the vector hopping is reset with each new radio frame.
  • the broad-beam signal is a Physical Broadcast Control Channel signal, and optionally the available bandwidth comprises a plurality of subcarriers and the frequency band is defined as central 72 subcarriers of the available bandwidth.
  • the low PAPR sequence is Discrete Fourier Transform Spread Orthogonal Frequency Division Multiplexing (DFT-S-OFDM) where the DFT-S-OFDM can optionally be used with Space-Time block coding based Transmit Diversity (STTD) .
  • the broad-beam signal is a Physical Downlink Control Channel signal, and optionally the Physical Downlink Control Channel signal is modulated with Orthogonal Frequency Division Multiplexing (OFDM) and Space-Frequency Transmit Diversity (SFTD) and optionally the low PAPR sequence is QPSK with iterative clipping to further reduce PAPR.
  • OFDM Orthogonal Frequency Division Multiplexing
  • SFTD Space-Frequency Transmit Diversity
  • the broad-beam signal is a Physical Downlink Shared Channel signal that is optionally modulated with Orthogonal Frequency Division Multiplexing (OFDM) and Space-Frequency Transmit Diversity (SFTD) and optionally the low PAPR sequence is QPSK with iterative clipping to further reduce PAPR.
  • OFDM Orthogonal Frequency Division Multiplexing
  • SFTD Space-Frequency Transmit Diversity
  • the low PAPR sequence is QPSK with iterative clipping to further reduce PAPR.
  • the Multiple-Input Multiple-Output (MIMO) transmitter has a number of antennas greater than a number of User Equipment (UE) serviced by the transmitter.
  • UE User Equipment
  • a Multiple-Input Multiple-Output (MIMO) transmitter for transmission of a broad-beam signal to User Equipment (UE) .
  • the MIMO transmitter comprises a power amplifier set configured to amplify the broad-beam signal, the power amplifier set transmitting the broad-beam signal over a frequency band narrower than an available bandwidth, the power amplifier set configured to modulate the broad-beam signal with a low Peak-to-Average-Power-Ratio, PAPR, sequence.
  • the low PAPR sequence is one of a Zadoff-Chu sequence and a Golay complementary sequence.
  • the broad-beam signal is a Primary Synchronization Signal and optionally, the available bandwidth comprises a plurality of subcarriers and the frequency band is defined as central 62 subcarriers of the available bandwidth.
  • the broad-beam signal is a Secondary Synchronization Signal and optionally the available bandwidth comprises a plurality of subcarriers and the frequency band is defined as central 62 subcarriers of the available bandwidth.
  • the transmitter further comprises vector hopping circuitry to introduce transmit diversity without affecting the low PAPR sequence, and optionally the vector hopping circuitry weighs two antennas alternating between [+1, +1] T and [+1, -1] T from subframe to subframe, where the vector hopping circuitry is optionally reset with each new radio frame.
  • the broad-beam signal is one of a Physical Broadcast Control Channel signal, Physical Downlink Control Channel signal, or Physical Downlink Shared Channel signal.
  • the broad-beam signal is encoded with Orthogonal Frequency Division Multiplexing (OFDM) and Space-Frequency Transmit Diversity (SFTD) .
  • OFDM Orthogonal Frequency Division Multiplexing
  • SFTD Space-Frequency Transmit Diversity
  • the transmitter modulates the broad-beam signal with a low PAPR sequence is performed by is QPSK with iterative clipping to further reduce PAPR.
  • the transmitter includes a second power amplifier set configured to amplify unicast signals.
  • the Multiple-Input Multiple-Output (MIMO) transmitter has a number of antennas greater than a number of User Equipment (UE) serviced by the transmitter.
  • UE User Equipment
  • a method for execution in a mobile device comprises receiving broad-beam signals from a transmitter over a frequency band narrower than an available bandwidth, the broad-beam signal modulated with a low Peak-to-Average-Power-Ratio, PAPR, sequence; and demodulating the broad-beam signals to extract content.
  • the demodulation of the broad-beam signals uses Discrete Fourier Transform Spread Orthogonal Frequency Division Multiplexing (DFT-S-OFDM) .
  • DFT-S-OFDM Discrete Fourier Transform Spread Orthogonal Frequency Division Multiplexing
  • the broad-beam signals are broadcast signals.
  • a mobile device comprising a receiver and a demodulator.
  • the receiver is configured to receive broad-beam signals from a transmitter over a frequency band narrower than an available bandwidth, the broad-beam signal modulated with a low Peak-to-Average-Power-Ratio (PAPR) sequence.
  • PAPR Peak-to-Average-Power-Ratio
  • the demodulator is configured to demodulate the broad-beam signals to extract content.
  • the demodulator uses Discrete Fourier Transform Spread Orthogonal Frequency Division Multiplexing (DFT-S-OFDM) .
  • DFT-S-OFDM Discrete Fourier Transform Spread Orthogonal Frequency Division Multiplexing
  • FIG. 1 illustrates a diagram of an embodiment wireless communications network
  • FIG. 2 illustrates a diagram of an embodiment transmitter architecture for M-MIMO
  • FIG. 3 illustrates diagrams of embodiment radio frequency channel structures for M-MIMO
  • FIG. 4 illustrates a diagram of another embodiment transmitter architecture for M-MIMO
  • FIG. 5 illustrates a diagram of another embodiment radio frequency channel structures for M-MIMO
  • FIG. 6 illustrates a physical layer diagram of a platform that may be used for implementing the devices and methods described herein, in accordance with an embodiment
  • FIG. 7 illustrates an exemplary block diagram of a mobile device for practicing principles of the present disclosure
  • FIG. 8 illustrates an exemplary block diagram of a system employing iterative clipping and filtering (ICF) as a low PAPR mechanism
  • FIG. 9 illustrates an exemplary flow diagram of iterative clipping and filtering (ICF) using FFT/IFFT.
  • aspects of the present disclosure may be embodied as a method, system, or computer program product. Accordingly, aspects of the present disclosure may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc. ) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a "circuit, " "module” , “mechanism” or “system” .
  • Field Programmable Gate Arrays (FPGAs) Field Programmable Gate Arrays
  • ASICs Application Specific Integrated Circuits
  • DSPs Digital Signal Processors
  • general purpose processors alone or in combination, along with associated software, firmware and glue logic may be used to construct the present disclosure.
  • aspects of the present disclosure may take the form of a computer program product on a computer-usable storage medium having computer-usable program code embodied in the medium.
  • Any suitable computer usable or computer readable medium may be utilized.
  • the computer-usable or computer-readable medium may be, for example but not limited to, a random access memory (RAM) , a read-only memory (ROM) , or an erasable programmable read-only memory (EPROM or Flash memory) .
  • Computer program code for carrying out operations of the present disclosure may be written in, for example but not limited to, an object oriented programming language, conventional procedural programming languages, such as the "C" programming language or other similar programming languages.
  • Various units, circuits, or other components may be described or claimed as “configured to” perform a task or tasks.
  • “configured to” is used to connote structure by indicating that the units/circuits/components include structure (e.g., circuitry) that performs the task or tasks during operation.
  • the unit/circuit/component can be configured to perform the task even when the specified unit/circuit/component is not currently operational (e.g., is not on) .
  • the units/circuits/components used with the "configured to” language include hardware -for example, circuits, memory storing program instructions executable to implement the operation, etc.
  • a unit/circuit/component is “configured to” perform one or more tasks is expressly intended not to invoke 35 U.S.C. 112 (f) , for that unit/circuit/component.
  • "configured to” can include generic structure (e.g., generic circuitry) that is manipulated by software and/or firmware (e.g., an FPGA or a general-purpose processor executing software) to operate in manner that is capable of performing the task (s) at issue.
  • "Configured to” may also include adapting a manufacturing process (e.g., a semiconductor fabrication facility) to fabricate devices (e.g., integrated circuits) that are configured to implement or perform one or more tasks.
  • a “module, ” a “unit” , an “interface, ” a “processor, ” an “engine, ” a “detector, ” a “mechanism, ” or a “receiver, ” typically includes a general purpose, dedicated or shared processor and, typically, firmware or software modules that are executed by the processor.
  • the module, unit, interface, processor, engine, detector, mechanism or receiver can be centralized or its functionality distributed and can include general or special purpose hardware, firmware, or software embodied in a computer-readable (storage) medium for execution by the processor.
  • a computer-readable medium or computer-readable storage medium is intended to include all mediums that are statutory (e.g., in the United States, under 35 U.S.C. 101) , and to specifically exclude all mediums that are non-statutory in nature to the extent that the exclusion is necessary for a claim that includes the computer-readable (storage) medium to be valid.
  • Known statutory computer-readable mediums include hardware (e.g., registers, random access memory (RAM) , non-volatile (NV) storage, to name a few) , but may or may not be limited to hardware.
  • the number of transmit antennas used by the access point exceeds the number of simultaneously served user equipments (UEs) to ensure data coverage via beam-forming gain.
  • UEs user equipments
  • Higher ratios of transmit antennas to simultaneously served UEs may achieve increased coverage, while lower ratios of transmit antennas to simultaneously served UEs may achieve increased throughput.
  • the network can trade throughput for coverage (and vice-versa) by adjusting the number of active UEs scheduled to receive simultaneous transmissions.
  • system information e.g., control, scheduling, etc.
  • system information is generally broadcast to many users in different spatial locations, and consequently it is typically desirable to maintain a uniform wave radiation pattern (i.e. broad-beam signals) for broadcast channels so that acceptable signal to noise (SNR) ratios can be maintained over the entire cell.
  • SNR signal to noise
  • unicast signals derive beam-forming gain performance benefits (i.e. with narrow-beam signals) by virtue of spatial selectivity, e.g., by achieving higher SNR ratios at the location of an intended receiver at the expense of lower SNR ratios at other locations.
  • a coverage gap between the broadcast and unicast channels may result if the same transmission drive circuitry (e.g., same amplifier set) is used to emit the unicast and broadcast signals.
  • the coverage gap would be approximately equal to the M-MIMO beam-forming gain for the unicast User Equipment (UE) and the isotropic radiation pattern for the broadcast signals.
  • UE User Equipment
  • the power distribution among antennas will have to be uneven, which further reduces coverage. Accordingly, techniques for allowing M-MIMO systems to efficiently communicate broadcast and unicast signals simultaneously without significant coverage gaps and/or uneven antenna power distributions are desired.
  • aspects of this disclosure use multiple power amplifier sets to communicate over a M-MIMO antenna array in order to improve signal performance when simultaneously emitting unicast and broadcast signals.
  • one power amplifier set is used for amplifying broad-beam signals (e.g. broadcast signals)
  • another power amplifier set is used for amplifying narrow-beam signals (e.g. unicast signals) .
  • the amplified narrow-beam and broad-beam signals are then combined, e.g., using radio frequency (RF) combiners, and the combination signal is broadcast over the M-MIMO array.
  • the broad-beam signals carry system information (e.g., control, scheduling, etc.
  • the narrow-beam signals carry non-system information (e.g., data, etc. ) .
  • Embodiments of this disclosure maintain transmit diversity for broadcast signals without significantly impacting the beam-forming gain experienced by narrow-beam signals.
  • the broad-beam power amplifier set is turned off (or powered down) during intervals in which broad-beam signals are not being emitted.
  • the broad-beam power amplifiers may require less functionality than those used in other systems (e.g., may only need to transmit over certain sub-bands) , which may allow for implementation of less complex and/or smaller power amplifiers (e.g., less expensive components) than those used in other systems, e.g., conventional M-MIMO and non-M-MIMO networks.
  • aspects of the disclosure may include antennas spaced significantly apart from one another in an antenna array for the broadcast signals to achieved improved diversity for broadcast information.
  • FIG. 1 illustrates a network 100 for communicating data.
  • the cellular communications network is a Long Term Evolution (LTE) cellular communications network.
  • LTE Long Term Evolution
  • the present invention is not limited thereto.
  • the present disclosure is applicable to any type of cellular communications network or wireless communications network having a downlink channel including multiple sub-carrier frequencies over which data is communicated.
  • the network 100 comprises an access point (AP) 110.
  • AP 110 may also be referred to as an enhanced node B (eNode B) .
  • Network 100 also has a coverage area 101, a plurality of mobile devices 120, and a backhaul network 130.
  • the AP 110 may comprise any component capable of providing wireless access by, inter alia, establishing uplink (dashed line) and/or downlink (dotted line) connections with the mobile devices 120, such as a base station, an enhanced base station (eNode B) , a femtocell, and other wirelessly enabled devices.
  • the mobile devices 120 may comprise any component capable of establishing a wireless connection with the AP 110, such as a user equipment (UE) , a mobile station (STA) , or other wirelessly enabled devices.
  • the backhaul network 130 may be any component or collection of components that allow data to be exchanged between the AP 110 and a remote end (not shown) .
  • the network 100 may comprise various other wireless devices, such as relays, low power nodes, etc.
  • FIG. 2 illustrates an embodiment of a power amplifier transmitter architecture 616a for M-MIMO.
  • the embodiment transmitter architecture 616a includes different power amplifier sets for broadcast (BC) data and unicast (UC) data.
  • the UC power amplifier set includes one amplifier for each antenna in the M-MIMO array 200, and only a subset of the M-MIMO array 200 (e.g. 2 antennas) are used for transmitting the BC signal. For each antenna in this subset, only one BC PA is connected to it. Since all the antennas are used for UC data transmission, each antenna in this subset can have a UC PA (i.e. M-MIMO PA) connected to it as well.
  • an RF combiner 202 is used to combine the signals before sending the signals to the respective antenna in the M-MIMO array 200.
  • the BC power amplifier set is periodically turned off or powered down between broadcast transmissions to save power.
  • the unicast and broadcast signals can be transmitted simultaneously.
  • the unicast and broadcast signals are communicated over different frequency bands.
  • the BC power amplifier sets may be adapted for narrow band broadcast transmission.
  • the UC power amplifier sets may be adapted for broadband unicast transmissions.
  • FIG. 3 illustrates embodiment radio frequency channel structures for M-MIMO.
  • the broadcast signals are communicated via narrowband transmissions, while the unicast signals are communicated via broadband transmissions, e.g., over portions of the frequency spectrum not occupied by the broadcast signals.
  • the broadcast signals may be transmitted over fewer than all the time intervals, and the broadcast PAs may be powered down during intervals in which the broadcast signals are not communicated. In such intervals, the unicast signals may be communicated over portions of the spectrum that were otherwise reserved for the broadcast signals, as demonstrated by the lower-most frequency channel structure.
  • Embodiments of this disclosure use two separate PAs specifically for system wide information broadcast.
  • the broadcast signal and the data signal are combined through an RF combiner 202 and then fed to the antennas.
  • the PAs for the broadcast signal can be periodically turned off when not being in use.
  • aspects of this disclosure provide comparable (to the data) coverage for the cell-wide system information broadcast, which may be a crucial technical component in M-MIMO networks.
  • Embodiments may be implemented in infrastructure equipment, e.g., access-points, etc.
  • FIG. 4 illustrates an alternative embodiment of a transmitter architecture 616b for M-MIMO.
  • the transmitter architecture 616b uses two separate power amplifiers to achieve system wide broadcast (high power PAs for unicast as well) .
  • unicast data is transmitted over different antennas than broadcast data in the M-MIMO array.
  • FIG. 5 illustrates an embodiment of radio frequency channel structures for M-MIMO.
  • the broadcast PAs are used for unicast transmission during intervals when the broadcast signal is not being transmitted.
  • Such a scenario may be particularly well adapted for highly mobile UEs, as the broadcast power amplifiers can occupy a broader portion of the bandwidth when they are also used for unicast.
  • the PAPR is a power characteristic that defines the average output power level of a power amplifier in a transmitter relative to the peak power.
  • a higher PAPR means that the power amplifier of the transmitter has to operate at a lower average power level.
  • a low PAPR means that the power amplifier at the transmitter can operate at a higher average power level relative to the peak power.
  • the PAPR of OFDM signals x (t) is defined as the ratio between the maximum instantaneous power and its average power:
  • x n the transmitted OFDM signals which are obtained by taking an Inverse Fast Fourier Transform (IFFT) operation on modulated input symbols x k .
  • IFFT Inverse Fast Fourier Transform
  • W represents the so-called “twiddle factor” wherein
  • a low PAPR sequence refers to a collection of information that has a relatively good autocorrelation characteristic.
  • the autocorrelation of a low PAPR sequence is the autocorrelation provided by a delta impulse function (also referred to as a Dirac delta function) .
  • a delta impulse function also referred to as a Dirac delta function
  • a Zadoff-Chu sequence is a complex-valued mathematical sequence which, when applied to a signal to be communicated wirelessly, results in an electromagnetic signal of constant amplitude.
  • Other low PAPR sequences can also be used, including binary sequences with a low PAPR.
  • Another example of a low PAPR sequence is a Golay complementary sequence.
  • a Golay complementary sequence has the property that their Fourier transform has a PAPR of at most 2, which is equivalent to 3 dB.
  • Other low PAPR sequences include so called Discrete Fourier Transform Spread Orthogonal Frequency Division Multiplexing (DFT-S-OFDM) (also known as single carrier FDMA in LTE) .
  • DFT-S-OFDM Discrete Fourier Transform Spread Orthogonal Frequency Division Multiplexing
  • FIG. 8 illustrating an exemplary block diagram of a system employing iterative clipping and filtering (ICF) as a low PAPR mechanism.
  • Input data is converted from a serial stream to a parallel output with serial to parallel converter 802.
  • QPSK mapper 804 modulates the parallel data representation and IFFT module 806 performs an Inverse Fast Fourier transform on the QPSK modulated data.
  • Parallel to serial converter 808 converts the parallel output of the IFFT module 806 back to a serial data stream for presentation to the low PAPR mechanism 810.
  • the low PAPR mechanism 810 (described in more detail herein below) has an input coupled to the parallel to serial converter 808 and an output coupled to a digital to analog converter 812.
  • FIG. 9 illustrating an exemplary flow diagram of the steps for iterative clipping and filtering (ICF) module 810 using FFT/IFFT. It should be appreciated that those skilled in the art will recognize other low PAPR clipping and filtering mechanisms (e.g. using DCT/IDCT transforms) without departing from the scope of the present disclosure.
  • the modulated symbol from parallel to serial converter 808 is coupled to the iterative clipping and filtering (ICF) module 810 and the number of iterations is set.
  • the peak of the incoming symbol is detected, and the clipping level is calculated for generating a symbol with clipped magnitude at step 902.
  • the clipped magnitude symbol is converted to a frequency domain signal using a FFT.
  • Step 906 filters the signal from step 904 to reduce noise.
  • the output from step 906 is converted into the time domain by using an IFFT. If the number of iterations set at step 900 is met, step 912 outputs the low PAPR symbol, otherwise another iteration of steps 902 –910 is made.
  • low or “reduced” PAPR in the context of OFDMA-based communications refers to any PAPR that is reduced according to a PAPR reduction mechanism (such as by using clipping and filtering or any of the sequences discussed above) such that the PAPR associated with the OFDMA-based communications is lower or reduced when compared to conventional OFDMA-based communications that are associated with relatively high PAPR.
  • the low PAPR that can be achieved using techniques according to some embodiments is on the order of the PAPR provided by a single-carrier, frequency division multiple access (SC-FDMA) communications system.
  • SC-FDMA frequency division multiple access
  • the low PAPR that can be achieved in OFDMA communications can be accomplished without having to apply a Digital Fourier Transform (DFT) to spread data over multiple sub-carriers, as performed with SC-FDMA.
  • DFT Digital Fourier Transform
  • Information to be transmitted may also be mapped to a selected at least one of the pool of low PAPR sequences.
  • the selected at least one low PAPR sequence is then modulated and transmitted wirelessly over the OFDMA-based wireless link.
  • an Orthogonal Frequency Division Multiple Access (OFDMA) channel is used as a downlink channel between the access point 110 and the UEs 120
  • a Single-Carrier Frequency Division Multiple Access (SC-FDMA) channel is used as an uplink channel for uplinks from the UEs 120 to the access point 110.
  • OFDMA and SC-FDMA are digital multi-carrier modulation schemes by which a number of closely-spaced sub-carrier frequencies are used to carry data.
  • a bandwidth (referred to herein as a full bandwidth) of the channel includes a number of sub-bands having corresponding sub-carrier frequencies.
  • the access point 110 identifies a subset of the sub-carrier frequencies in the full bandwidth of the downlink channel as a reduced bandwidth channel for the downlink to the UE 120.
  • FIG. 3 depicts PSS and SSS common broadcast signals being transmitted in accordance with the principles of the present disclosure over the narrow band of sixty-two subcarriers.
  • transmit power density, or signal power density is concentrated on the sixty-two sub-carrier frequencies in the reduced bandwidth channel rather than spread across the sub-carrier frequencies in the full bandwidth of the downlink channel.
  • a power boost is provided for the downlink to the UE 120.
  • Vector hopping can be used to introduce transmit diversity.
  • Precoding vector hopping is a known transmit diversity scheme in which each symbol is multiplied by a constant, which would not affect the low PAPR property.
  • the weighting of the two antennas preferably alternates between [+1, +1] T and [+1, -1] T from subframe to subframe, and is reset at the beginning of a new radio frame, wherein T denotes vector transpose.
  • PSS and SSS are transmitted from the same antenna port in any given subframe. However, between different subframes they are preferably transmitted from different antenna ports thus benefitting from time-switched antenna diversity.
  • the antenna ports do not necessarily correspond to physical antennas, but rather are logical entities distinguished by their reference signal sequences. Multiple antenna port signals can be transmitted on a single transmit antenna. Correspondingly, a single antenna port can be spread across multiple transmit antennas.
  • DFT-S-OFDM with space-time block coding based transmit diversity can be used to reduce PAPR in PBCH.
  • DFT-S-OFDM has very low PAPR for Quadrature Phase Shift Keying (QPSK) modulation and negligible performance degradation from DFT-S-OFDM transmission is observed.
  • QPSK Quadrature Phase Shift Keying
  • the seventy-two subcarriers cover an almost flat channel.
  • PBCH is preferably designed for the worst case UE, where degradation of STTD due to UE mobility is small.
  • STTD Space time transmit diversity
  • STBC space time block code
  • One aim of STTD is to smooth the Rayleigh fading and drop out effects observed when using only a single antenna at both ends of a radio link in a multipath propagation environment. Diversity improves link reliability for each UE, especially near cell edges and also the average performance of an ensemble of users at any particular instant.
  • STTD is applied to subcarrier symbols taking consecutive pairs of data symbols ⁇ S1, S2 ⁇ , normally sent directly from one antenna. For two transmit antennas the symbols ⁇ S1, S2 ⁇ are transmitted unchanged from antenna #1 while simultaneously from antenna #2 is sent the sequence ⁇ -S2*, S1* ⁇ .
  • SFTD Space-Frequency Transmit Diversity
  • SFBC Space-Frequency Block Coding
  • PAPR reduction can be “more aggressive” because even though UE transparent PAPR reduction usually causes larger Error Vector Magnitude (EVM) , PDCCH and PDSCH use QPSK modulation and QPSK modulation is able to endure larger EVM.
  • UE transparent PAPR reduction refers to the fact that a UE does not need to know what PAPR reduction technique is used at the transmitter to receive the data.
  • EVM is a measure used to quantify the performance of a transmitter (or receiver) .
  • a signal sent by an ideal transmitter or received by an ideal receiver would have all constellation points precisely at the ideal locations, however various imperfections in the implementation (such as carrier leakage, low image rejection ratio, phase noise etc. ) cause the actual constellation points to deviate from the ideal locations.
  • EVM is a measure of how far the points are from the ideal locations.
  • EVM Since noise, distortion, spurious signals, and phase noise all contribute to the deviation of the constellation points from the ideal location, EVM therefore provides a comprehensive measure of the quality of the radio receiver or transmitter for use in digital communications.
  • One of the stages in a typical phase-shift keying demodulation process produces a stream of I-Q points which can be used as a reasonably reliable estimate for the ideal transmitted signal in EVM calculation.
  • the EVM is determined by how severely the signals are clipped. The more severely the signals are clipped, the lower the PAPR, but the higher the EVM. Since QPSK can endure more severe EVM than higher modulations, more clipping can be done, or alternatively stated -lower PAPR can be achieved.
  • the phrase “more aggressive” refers to more reduction in PAPR. Usually when PAPR reduction is performed the modulation order for a given signal is not known. When the signal is known to be QPSK, lower PAPR can be achieved at the cost of higher EVM. The phrase "more aggressive” is relative to the modest PAPR reduction when the modulation order of the signal is not known.
  • FIG. 6 depicting an exemplary but not exclusive physical layer diagram of a platform that may be used for implementing systems, devices and methods described herein, in accordance with embodiments.
  • Transport block data is passed through a cyclic redundancy check (CRC) module 600 for error detection.
  • CRC cyclic redundancy check
  • the CRC module 600 appends a CRC code to the transport block data received from a MAC layer before being passed through the physical layer.
  • the transport block is divided by a cyclic generator polynomial to generate parity bits. These parity bits are then appended to the end of transport block.
  • the physical layer comprises a channel coding module 601, a rate matching module 602, a scrambler module 604, a modulation mapper module 606, a layer mapping module 608, a pre-coding module 610, a resource element mapper 612, a signal generator (OFDMA) module 614, and a power amplifier module 616.
  • a channel coding module 601 a rate matching module 602, a scrambler module 604, a modulation mapper module 606, a layer mapping module 608, a pre-coding module 610, a resource element mapper 612, a signal generator (OFDMA) module 614, and a power amplifier module 616.
  • OFDMA signal generator
  • Channel coding module 601 turbo codes the data with convolutional encoders having certain interleaving between them.
  • the rate matching module 602 acts as a rate coordinator or buffer between preceding and succeeding transport blocks.
  • the scrambler module 604 produces a block of scrambled bits from the input bits.
  • a RB is a collection of resource elements.
  • a resource element is a single subcarrier over one OFDM symbol, and carries multiple modulated symbols with spatial multiplexing.
  • a RB represents the smallest unit of resources that can be allocated.
  • a RB is a unit of time frequency resource, representing 180 KHz of spectrum bandwidth for the duration of a 0.5 millisecond slot.
  • Modulation mapper module 606 maps the bit values of the input to complex modulation symbols with the modulation scheme specified.
  • the modulation scheme is Discrete Fourier Transform Spread Orthogonal Frequency Division Multiplexing (DFT-S-OFDM) .
  • the modulation scheme is OFDM with aggressive PAPR reduction.
  • Layer mapper module 608 splits the data sequence into a number of layers.
  • Precoding module 610 is based on transmit beam-forming concepts allowing multiple beams to be simultaneously transmitted in the M-MIMO system by a set of complex weighting matrices for combining the layers before transmission.
  • Vector hopping is preferably used for transmit diversity.
  • Precoding module 610 preferably vector hops with the weighting of the two antennas alternating between [+1 , +1] T and [+1 , -1] T from subframe to subframe, and resetting at the beginning of a new radio frame.
  • the resource element mapping module 612 maps the data symbols, the reference signal symbols and control information symbols into a certain resource element in the resource grid.
  • the PA array 616 drives the antenna array 200 and preferably has a form substantially that of either PA array 616a or 616b depicted in FIGs 2 and 4, respectively.
  • the PA array 616 transmits the common broadcast channels (e.g. PSS, SSS, PBCH, PDCCH and PDSCH) over a narrow sub-band resource as depicted in FIG. 3.
  • Discrete Fourier Transform Spread Orthogonal Frequency Division Multiplexing (DFT-S-OFDM) or OFDM is preferably used with aggressive PAPR reduction for the broadcast signal to further lower the rating requirement of the dedicated PAs within the PA array 616.
  • a processing module 700 performs radio baseband functions. These functions can be carried out using a number of different implementations including Digital Signal Processors (DSPs) , Field Programmable Gate Arrays (FPGAs) , Application Specific Integrated Circuits (ASICs) , general purpose processors, software, or a combination thereof.
  • DSPs Digital Signal Processors
  • FPGAs Field Programmable Gate Arrays
  • ASICs Application Specific Integrated Circuits
  • the methods used to modulate and demodulate the input and outputs signals may use a variety of methodologies, including but not limited to, middleware, e.g., common object request broker architecture (CORBA) , or virtual radio machines, which are similar in function to JAVA virtual machines.
  • middleware e.g., common object request broker architecture (CORBA)
  • CORBA common object request broker architecture
  • virtual radio machines which are similar in function to JAVA virtual machines.
  • Processing module 700 performs the methods of receiving broad-beam signals from a transmitter over a frequency band which is much narrower than an available bandwidth and demodulating the broad-beam signals to extract content, in accordance with principles of the present disclosure.
  • the demodulator preferably demodulates Discrete Fourier Transform Spread Orthogonal Frequency Division Multiplexing (DFT-S-OFDM) coded signals.
  • DFT-S-OFDM Discrete Fourier Transform Spread Orthogonal Frequency Division Multiplexing
  • An antenna or antennas 702 provides gain versus direction characteristic to minimize interference, multipath, and noise.
  • the RF signal is picked up by the antenna (s) 702, filtered, amplified with a low noise amplifier (LNA) , and down converted with a local oscillator (LO) to baseband (or IF) by flexible RF hardware 704.
  • the incoming signal is digitizing with an analog to digital converter (ADC) 706.
  • ADC analog to digital converter
  • DAC digital to analog converter
  • Digital filtering (channelization) and sample rate conversion are provided by module 708 to interface the output of the ADC 706 to the processing module 700.
  • module 708 provides digital filtering and sample rate conversion to interface the processing module 700 that creates the modulated waveforms to the digital to analog converter 706.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

L'invention concerne des procédés et des dispositifs de signalisation à faible facteur de crête (PAPR) pour un canal commun, comprenant un ensemble amplificateur de puissance conçu pour transmettre des signaux à faisceau large sur une bande de fréquences plus étroite que la largeur de bande disponible et modulée par une séquence à faible valeur de crête (PAPR). Un deuxième ensemble amplificateur de puissance peut être conçu pour transmettre des signaux de monodiffusion à faisceau étroit.
PCT/CN2015/089353 2014-03-07 2015-09-10 Signalisation à faible facteur de crête pour un canal de diffusion commun dans des systèmes mimo WO2016041463A1 (fr)

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JP2017515158A JP2017535996A (ja) 2014-03-07 2015-09-10 マッシブｍｉｍｏシステムにおける共通ブロードキャストチャネルの低ｐａｐｒシグナリング
CN201580047003.3A CN106716947B (zh) 2014-03-07 2015-09-10 一种用于向ue传输宽波束信号的方法及mimo发射器
EP15842853.2A EP3186938A4 (fr) 2014-09-18 2015-09-10 Signalisation à faible facteur de crête pour un canal de diffusion commun dans des systèmes mimo

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WO2018006982A1 (fr) * 2016-07-08 2018-01-11 Telefonaktiebolaget Lm Ericsson (Publ) Procédé et appareil d'émission avec antennes multiples
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WO2018130093A1 (fr) * 2017-01-13 2018-07-19 维沃移动通信有限公司 Procédé de transmission de groupe de signaux d'accès de synchronisation, procédé de réception de groupe de signaux d'accès de synchronisation, dispositifs associés et système
CN108418646A (zh) * 2017-02-10 2018-08-17 维沃移动通信有限公司 同步接入信号组的发送方法、接收方法、相关设备及系统
CN110719625A (zh) * 2019-10-18 2020-01-21 海能达通信股份有限公司 一种ssb的发送方法及装置、基站、系统

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CN105790813A (zh) * 2016-05-17 2016-07-20 重庆邮电大学 一种大规模mimo下基于深度学习的码本选择方法
CN105790813B (zh) * 2016-05-17 2018-11-06 重庆邮电大学 一种大规模mimo下基于深度学习的码本选择方法
JP2018006866A (ja) * 2016-06-28 2018-01-11 Kddi株式会社 被制御側装置における所定機能の起動時刻を制御する制御側装置、プログラム及び方法
WO2018006982A1 (fr) * 2016-07-08 2018-01-11 Telefonaktiebolaget Lm Ericsson (Publ) Procédé et appareil d'émission avec antennes multiples
WO2018130093A1 (fr) * 2017-01-13 2018-07-19 维沃移动通信有限公司 Procédé de transmission de groupe de signaux d'accès de synchronisation, procédé de réception de groupe de signaux d'accès de synchronisation, dispositifs associés et système
CN108307496A (zh) * 2017-01-13 2018-07-20 维沃移动通信有限公司 同步接入信号组的发送方法、接收方法、相关设备及系统
CN108418646A (zh) * 2017-02-10 2018-08-17 维沃移动通信有限公司 同步接入信号组的发送方法、接收方法、相关设备及系统
CN110719625A (zh) * 2019-10-18 2020-01-21 海能达通信股份有限公司 一种ssb的发送方法及装置、基站、系统
CN110719625B (zh) * 2019-10-18 2024-02-02 海能达通信股份有限公司 一种ssb的发送方法及装置、基站、系统

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