WO2011093834A1 - Techniques offrant une réduction de puissance de crête et de la diversité dans des télécommunications sans fil - Google Patents

Techniques offrant une réduction de puissance de crête et de la diversité dans des télécommunications sans fil Download PDF

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Publication number
WO2011093834A1
WO2011093834A1 PCT/US2010/000221 US2010000221W WO2011093834A1 WO 2011093834 A1 WO2011093834 A1 WO 2011093834A1 US 2010000221 W US2010000221 W US 2010000221W WO 2011093834 A1 WO2011093834 A1 WO 2011093834A1
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Prior art keywords
constellation
qam
signals
extended
representative
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PCT/US2010/000221
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English (en)
Inventor
Douglas L. Jones
Theodoros Tsiligkaridis
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The Board Of Trustees Of The University Of Illinois
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Priority to PCT/US2010/000221 priority Critical patent/WO2011093834A1/fr
Publication of WO2011093834A1 publication Critical patent/WO2011093834A1/fr

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    • 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
    • H04L27/3405—Modifications of the signal space to increase the efficiency of transmission, e.g. reduction of the bit error rate, bandwidth, or average power
    • H04L27/3411—Modifications of the signal space to increase the efficiency of transmission, e.g. reduction of the bit error rate, bandwidth, or average power reducing the peak to average power ratio or the mean power of the constellation; Arrangements for increasing the shape gain of a signal set
    • 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 invention relates to telecommunications, and more particularly, but not exclusively relates to wireless communication methods, systems, devices, and apparatus involving peak power reduction and communication signal diversity.
  • Orthogonal frequency-division multiplexing is known to be the primary modulation scheme for high data rate wireless digital communication.
  • Many standards including the emerging 802.1 In MIMO standard, the European terrestrial digital audio and television broadcast (DAB-T and DVB-T) standards, as well as the 802.16 (WiMAX) standard, all include the use of OFDM, and it is expected that many future standards will be based on OFDM.
  • OFDM has many distinct advantages, including balanced complexity between the transmitter and the receiver, highly efficient use of available bandwidth, the ability to achieve channel capacity when performing optimal power allocation, and the ability to deal effectively with frequency-selective channels through cross-channel convolutional coding.
  • PAPR peak-to-average power ratio
  • Nonlimiting examples of PAPR reduction techniques include clipping, tone reservation, partial transmit sequences, and active constellation extension (ACE). Depending on the particular implementation one or more of these techniques may be appropriate together or in the alternative.
  • ACE active constellation extension
  • PAPR reduction can increase as the number of OFDM subchannels increase, making it particularly attractive for applications using a large number of subcarriers (i.e., digital broadcasting); Indeed, ACE is an accepted PAPR reduction scheme set forth in the DVB-T2 standard.
  • diversity applications exploit the fact that individual channels experience different levels of fading and interference, such that multiple versions of the same signal may be transmitted and/or received and combined in the receiver, and/or a redundant forward error correction code may be added and different parts of the message transmitted over different channels.
  • Diversity techniques may exploit the multipath propagation, resulting in a diversity gain, often measured in decibels.
  • classes of diversity can be identified, including without limitation: (1) Time diversity in which multiple versions of the same signal are transmitted at different time instants; alternatively, a redundant forward error correction code is added and the message is spread in time by means of bit-interleaving before it is transmitted; (2)
  • Space diversity involving transfer of the signal over several different propagation paths, which for wired transmission can be achieved by transmitting via multiple wires and which for wireless transmission can be achieved by antenna diversity using multiple transmitter antennas (transmit diversity) and/or multiple receiving antennas (reception diversity); (3) Polarization diversity involving transmission/reception of multiple versions of a signal with different polanzation; (4) Multiuser diversity, which can be implemented by opportunistic user scheduling at either the transmitter or the receiver; (5) Cooperative diversity, which results in antenna diversity gain by using the cooperation of distributed antennas belonging to each node; and (6) Frequency ! diversity in which the signal is transferred using several frequency channels or spread over a wide spectrum that is affected by frequency-selective fading, including OFDM modulation in combination with subcarrier interleaving and forward error correction.
  • the DVB-T2 standard permits implementation of diversity by a rotated constellation technique or a variant of space-frequency block coded Alamouti.
  • One embodiment of the present invention is a unique technique providing both PAPR reduction and telecommunication diversity.
  • Other embodiments provide unique methods, systems, devices, and apparatus to process communication signals, including implementation of PAPR reduction, diversity, and/or other features. Further embodiments, forms, features, aspects, benefits, and advantages of the present application shall become apparent from the description and figures provided herewith.
  • Fig. 1 is a diagrammatic view of a wireless communication system including schematic representations of a transmitting device (TXR) and a receiving device (RXR).
  • TXR transmitting device
  • RXR receiving device
  • Fig. 2 is a flowchart depicting an operating procedure employing ACE with diversity for an OFDM-based wireless communication technique that may be implemented with the system of Fig. 1.
  • Fig. 3 is a constellation representative of quadrature amplitude modulation (QAM) having any of 16 possible complex numbers spaced apart in the complex number plane in terms of the Q (or equivalently quadrature or imaginary (IM)) and I (or equivalently in-phase or real (RE)) axes (collectively, 16-QAM) that corresponds to certain data encoding that may be performed by the TXR in accordance with the procedure of Fig. 4.
  • QAM quadrature amplitude modulation
  • Fig. 4 is a diagrammatic plot of the constellation depicted in Fig. 3 with rotation by a selected angle to incorporate telecommunication diversity representative of further data encoding that may be performed by the TXR in accordance with the procedure of Fig. 4.
  • Representation of this rotated constellation by each of two pulse amplitude modulation (PAM) projections is further diagrammatically depicted, with each PAM projection being capable of representing any of 16 possible modulation symbols (16-PAM).
  • PAM pulse amplitude modulation
  • Fig. 5 is a further diagrammatic plot corresponding to a rotated form of a 16-QAM constellation with a pair of 16-PAM projections each representative of the rotated constellation.
  • Fig. 6 is a plot representative of an extended 16-QAM constellation rotated by an angle of 16.8° in the complex IQ plane with constellation extensions according to the disclosed method.
  • Fig. 7 is a plot representative of an extended quadrature phase-shift Keying (QPSK or equivalently 4-QAM) constellation rotated by an angle of 29° in the complex (IQ) plane with constellation extensions according to the disclosed method.
  • QPSK quadrature phase-shift Keying
  • Fig. 8 is a plot diagrammatically depicting Active Constellation Extension (ACE) for a 16-QAM implementation.
  • ACE Active Constellation Extension
  • Fig. 9 is a graph illustrating CCDF results for a 16-QAM implementation with 256 and 1024 subcarriers, respectively.
  • Fig. 10 is a graph illustrating CCDF results for a QPSK implementation with 256 and 1024 subcarriers, respectively.
  • one embodiment of the present invention is a unique technique that combines PAPR reduction and telecommunication diversity. Furthermore, this result is surprisingly unexpected in view of its inconsistency with the content of the DVB-T2 standard. Transmit diversity may be provided by preparing multiple representations of the same encoded information for wireless transmission over different channels from a common transmitting device. Representations of unrelated information are grouped together in a composite transmission cell, while representations for the same encoded information are sent in different composite transmission cells over different channels. Each composite transmission cell is processed to provide PAPR reduction before transmission, which may include ACE.
  • Fig. 1 illustrates system 20 of another embodiment of the present application.
  • System 20 includes wireless transmission device 30 spaced apart from wireless receiving device 70.
  • Device 30 includes a wireless transmitter (TXR) and device 70 includes a wireless receiver (RXR).
  • Device 30 may be a dedicated transmitter without receiving capability, or alternatively may further include one or more receivers and/or other transmitters either partially or completely integrated together in the form of one or more transceivers or provided as separate transmitters and/or receivers in the same communication device.
  • Device 70 may be a dedicated receiver without transmitter capability, or alternatively may further include one or more transmitters and/or other receivers either partially or completely integrated together in the form of one or more transceivers or provided as separate transmitters and/or receivers in the same
  • System 20 may be implemented with devices 30 and 70 serving as transmitting and/or receiving nodes, respectively, in a wireless computer network; as equipment in a wireless telephone system; as equipment in a satellite-based communication network or dedicated communication link, and/or as equipment in a broadcasting implementation ⁇ just to
  • device 30 is a relatively high power television (or similar media) broadcasting station and device 70 is one of many televisions or other compatible broadcast reception equipment.
  • device 30 or device 70 may be a communication signal repeater that relays signals along dedicated communication pathways and/or is routed through any of a number of possible i pathways in a network arrangement, or the like.
  • wireless communication depicted is of a Radio Frequency (RF) type; the communication techniques described herein may be applied for other wireless transmission types, such as those based on Infrared (IR), acoustic waveforms (sonic and/or ultrasonic), visible light, and/or other varieties known to those skilled in the art.
  • RF Radio Frequency
  • devices 30 and/or 70 may also be equipped with "wired” or cable-based communication links/interfaces.
  • Device 30 includes processor 32 with memory 34 in operative communication with Analog Front End (AFE) 40.
  • AFE Analog Front End
  • Processor 32 executes operating logic to perform various transmission operations and procedures as further described in connection with Figs. 2-10.
  • AFE 40 operations/procedures include processing digital signals for wireless transmission that are provided to AFE 40, which may include encoding/formatting for the desired transmission protocol.
  • AFE 40 is depicted with a Digital-to- Analog (D/A) converter 42 that i converts its digital input from processor 32 to an analog format.
  • D/A converter 42 Digital-to- Analog converter 42 that i converts its digital input from processor 32 to an analog format.
  • the resulting analog signals output by D/A converter 42 are input to a High Power Amplifier (HP A) 44.
  • AFE 40 may include other components as needed to implement the operations/procedures described herein (not shown), such as modulators, filters, oscillators, power sources, limiters, comparators, multipliers, amplifiers, phase-locked loops, and the like to facilitate RF up-conversion and
  • AFE 4.0 is in operative communication with antenna 50 that wirelessly transmits RF electromagnetic signals output by AFE 40.
  • Device 70 (receiver RXR) includes antenna 60 that receives wireless communication signals transmitted by device 30 via antenna 50.
  • Device 70 includes processor 72 with memory i 74 in operative communication with Analog Front End (AFE) 80.
  • AFE Analog Front End
  • receiver operating logic to perform various operations and procedures to facilitate reception of wireless signals output by device 30 as further described in connection with Figs. 4-10. These operations/procedures include processing digital signals representative of information received from device 30, which may include decoding/formatting/restoration of information as input to ) device 30 for transmission.
  • AFE 80 is depicted with analog filter 84 and Analog-to-Digital (A/D) converter 82.
  • Filter 84 receives input corresponding to the signal received with antenna 60 and provides filtered output to A/D converter 82 that converts a filtered analog input to a digital output. This digital output is provided to processor 72.
  • AFE 80 may include other components as needed to implement the operations/procedures described herein (not shown), such as demodulators, filters, oscillators, power sources, limiters, comparators, multipliers, amplifiers, phase-locked loops, and the like to facilitate RF down-conversion and restoration of the information provided to device 30 for transmission.
  • Processors 32 and 72 each include appropriate signal conditioners to transmit and receive desired information (data), and correspondingly may include filters, amplifiers, limiters, CODECs, encoders, decoders, modulators, demodulators, multipliers, clamps, power supplies, power converters, and the like as needed to perform various control, communication, and regulation operations described herein.
  • Processor 32 and 72 each can be comprised of one or more components of any type suitable to process digital signals and provide desired output signals. Such components may include digital circuitry, analog circuitry, or a combination of both. As depicted each processor 32 and 72 is of a programmable type; a dedicated, hardwired state machine; or a combination of these; and can further include multiple processors,
  • processors 32 and 72 are each of a programmable variety that executes algorithms and processes data in accordance with its corresponding operating logic as defined by programming instructions (such as software or firmware) stored in memory 34 or 74, respectively. Alternatively or additionally, operating logic for either processor is at least partially defined by hardwired logic or other dedicated hardware.
  • Memory 34 and/or 74 may be of one or more types, such as a solid-state variety, electromagnetic variety, optical variety, or a combination of these forms; and can be volatile, nonvolatile, or a mixture of these types. Some or all of memory 34 and/or 74 can be of a portable variety, such as a disk, tape, memory stick, cartridge, or the like. Memory 34 and/or 74 can store data that is manipulated by processor operating logic, such as data representative of signals transmitted and/or received in addition to or in lieu of storing programming instructions defining such operating logic, just to name one example.
  • processor operating logic such as data representative of signals transmitted and/or received in addition to or in lieu of storing programming instructions defining such operating logic, just to name one example.
  • processor 32 and 72 may be the same type of unit each with operating logic corresponding to its associated operations/procedures, and each may include I other operating logic, including that of the other processor.
  • processor 32 and 72 may be the same type of unit each with operating logic corresponding to its associated operations/procedures, and each may include I other operating logic, including that of the other processor.
  • processors 32 and 72 may differ from each other and/or be dedicated to its specific operations.
  • Fig. 2 is a flowchart depicting OFDM communication procedure 120 that implements both transmit diversity in the form of a technique corresponding to a QAM constellation rotated by a selected angle and PAPR reduction in the form of ACE.
  • QAM refers to i any type of quadrature amplitude modulation, including but not limited to, QPSK, 4-QAM, 16- QAM, 64-QAM, and 256-QAM. It should be appreciated that in other embodiments, other PAPR reduction and/or diversity techniques may be combined and applied, PAPR reduction and diversity are combined for application with a modulation protocol other than OFDM, and/or constellations/representations other than QAM may be the used.
  • System 20, including operating > logic of processors 32 and 72, is structured to implement procedure 120.
  • a "constellation” refers to a representation of all the valid modulation symbols possible for a given digital modulation scheme (including but not limited to QAM) as a uniquely positioned points on the complex plane. Collectively, these modulation symbols comprise the modulation alphabet.
  • the real (RE) and imaginary (IM) axes may alternatively be designated the in-phase or I-axis and the quadrature or Q-axis, respectively. Accordingly, a constellation may be regarded as a form of signal space diagram.
  • tellation diagram refers to the display of an actual signal as a two-dimensional scatter diagram in the complex plane at symbol sampling instants.
  • a point in a constellation diagram typically deviates from the more ideal position of its corresponding modulation symbol in the ideal constellation because of noise, distortion, or the like.
  • Procedure 120 includes a transmission module 130 that is implemented with device 30 and reception module 170 that is implemented with device 70.
  • transmission module 130 that is implemented with device 30
  • reception module 170 that is implemented with device 70.
  • I procedure 120 begins with operation 132 of module 130.
  • operation 132 information is
  • This information is provided in the form of an input bit stream to be processed by processor 32 in accordance with- its transmission operating logic.
  • constellation C represents 16 modulation symbols of a ⁇ modulation alphabet for the 16-QAM modulation technique. Each point is shown with one of 16 unique binary values (0000-11 11) relative to the I and Q axes in the complex plane. As represented by constellation C, each potential value corresponds to a complex number. As data is encoded relative to constellation C, one of these 16 values is assigned, each corresponding to a different position along the complex space of the IQ plane. The result is a QAM-modulated data
  • IDFT inverse Discrete Fourier Transform
  • the input bit stream is modulated into blocks of QAM symbols (N symbols each)
  • the y ' th complex-valued symbol vector (X j ) is transmitted in parallel such that each QAM symbol modulates a different subcarrier from a set of N subcarriers total.
  • procedure 120 proceeds with operation 134.
  • i diversity is incorporated by applying a rotated constellation technique.
  • the rotated constellation technique may be implemented by forward mapping the unrotated constellation C into rotated constellation RC for use as the corresponding modulation symbol source.
  • Fig. 4 diagrammatically depicts a rotated 16-PAM constellation RC, rotated by angle RA.
  • > the yth complex-valued symbol vector X j established with constellation C is the y ' th N-channel- long Forward Error Correction (FEC) block outputted by a FEC encoding module (such as the LDPC encoder).
  • FEC Forward Error Correction
  • This block's real and imaginary parts are rotated by a constant rotation angle depending on the constellation size, and the imaginary part is cyclically delayed by one channel within every FEC block.
  • the output channels are given by (2a) and (2b) as follows: where the rotation phase is given by (3) as follows:
  • the in-phase (I) and quadrature (Q) i components of a rotated constellation are formed in a QAM modulation processing module.
  • the 16-QAM constellation C has two independent projections PI and P2.
  • Projections PI and P2 each correspond to a pulse amplitude modulation (PAM) representation, a 4-PAM, that are independent of each other.
  • Fig. 4 diagrammatically depicts a rotated 16-PAM constellation RC, I rotated by angle RA.
  • Constellation RC corresponds to two 16-PAM projections P3 and P4; however, unlike the unrotated constellation C, projections P3 and P4 are related, such that either can represent the same information included in constellation RC (or constellation C before rotation).
  • Fig. 5 further depicts projections P3 and P4 in terms of the binary values (0000-1 1 11) each can represent - having the same degree of quantization as the 16-QAM format from which
  • Procedure 120 continues with operation 136, in which the projections P3 and P4 are realized. It should be appreciated that projections P3 and P4 each represent the same information encoded in the underlying constellation C (and RC).
  • procedure 120 continues with operation 138.
  • operation 138 In operation 138,
  • projection P3 (a 4-PAM representation) is combined with a different 4-PAM projection
  • the 256-QAM-like composite representations have points that are non-uniformly spaced.
  • procedure 120 continues with operation 140.
  • PAPR reduction is applied using the ACE technique.
  • the analog PAPR of an OFDM symbol block can be computed according to (4) as follows:
  • CCDF complementary cumulative distribution function
  • CCDF Pr[PAPR > y ] (5)
  • ACE has gained popularity as demonstrated by its inclusion in the DVB-T2 standard.
  • This technique differs from other techniques in that it does not tend to sacrifice bandwidth or bit error rate (BER) performance.
  • BER bit error rate
  • It is an iterative scheme that works by extending the outer QAM constellation points outwards, such that the relative position of the outer points change relative to the interior constellation points in the IQ plane, as symbolically illustrated in Fig. 8 by the outward pointing arrows. Corner constellation points can be extended outwards into quarter- plane regions, while side points can only be extended in one direction. Interior points cannot move because the BER might increase.
  • a fast technique exists that is based on a smart gradient project (SGP) algorithm that can reduce PAPR significantly in as little as two iterations. This algorithm is further described in B. S. Krongold and D. L. Jones, "PAR reduction in OFDM via active constellation extension," IEEE Transactions on Broadcasting, vol. 49, pp. 258-268, September 2003, which is hereby incorporated by reference
  • SGP-implemented ACE is applied to each composite constellation to
  • procedure 120 continues with operation 142.
  • the ACE composite constellation provided by i operation 140 is encoded for OFDM transmission. Accordingly, the two PAM projections from a given rotated constellation are encoded into different OFDM cells.
  • the modified constellation-based data that has been processed for both rotated constellation diversity and ACE-based PAPR reduction from operation 142 is transmitted by device 30.
  • Procedure 120 then continues with reception module 170, in which the transmitted signal is received in operation 172 with device 70.
  • Procedure 120 continues with operation 174.
  • operation 174 the original data is restored from the received signals generally by reversing the operations of transmission module 130.
  • Procedure 120 continues with conditional 190, which tests whether to continue processing data for transmission/reception with modules 130 and 170, i respectively. If the test of conditional 190 is true (yes), procedure 120 loops back to operation 132 of transmission module 130. If the test of conditional 190 is false (no), procedure 120 then terminates.
  • SNR signal-to-noise
  • two steps may be taken with device 70 to ) avoid bit-error-rate (BER) increase due to the induced ACE extensions.
  • BER bit-error-rate
  • the extended constellation points are projected back to their rotated-and-cyclically-shifted constellation points and inverse mapping takes place to recover
  • low SNR scenarios and severe fading i.e., fading channels characterized by long delay- spreads
  • projection may not be sufficient. Thus, other alternatives might be considered.
  • a third alternative is to modify the log-likelihood ratios that are usually used to make hard or soft decisions on the coded bits. Inner and outer decoding follow to recover the information bits.
  • a further alternative is to modify the demodulator and decoder unit and use soft-input soft-output (SISO) demodulation and decoding, in a manner similar to that described for tone injection for > coded-OFDM systems.
  • SISO soft-input soft-output
  • the a posteriori coded bit information provided by the demodulator can be used to initialize the regular sum-product (or min-sum) inner LDPC decoder properly. It is envisioned that this alternative would provide a viable enhancement to the DVB-T2 standard because OFDM is almost always used in conjunction with coding and this decoding scheme is compatible with the iterative demodulation-decoding that turbo-coded
  • Figs. 6 and 7 show example runs of the extended constellations for 16-QAM and QPSK original constellations, respectively. As shown, only the outer constellation points are moved, and since the clipping threshold, A, is not set too low, the outer rotated constellation points tend to remain clustered near their original locations. It is worthwhile to note that setting the clipping threshold unrealistically low leads to convergence problems, since outer constellation points tend to shoot outwards too far and subsequent iterations have difficulty lowering the PAPR. On the other hand, setting the clipping threshold too high may not unlock the full PAPR reduction potential of ACE. Figs.
  • FIG. 6 and 7 show that the average transmit energy is slightly increased by 0.58 dB and 0.84 dB under 16-QAM and QPSK modulation respectively (for 256 subchannels), to lower the peak level of the transmit analog signal.
  • An example of the ACE- SGP algorithm results for SISO OFDM on rotated constellations is shown in Fig. 9.
  • the rotation angles were obtained with four ACE-SGP
  • ACE peak-power reduction can also be applied in the MISO mode that the DVB-T2 standard describes as an option for obtaining transmit diversity, where a variant of space- frequency block-coded Alamouti is used.
  • one embodiment is directed to a method, comprising: representing communication information with a data structure corresponding to a quadrature modulation constellation;
  • Optional variants of this embodiment include the inventions of: wirelessly receiving the one or more extended constellation signals and deriving the communication information from the one or more extended constellation signals corresponding to a projection of the rotated form of the quadrature modulation constellation, wherein the quadrature modulation constellation is at least one of: a 4-QAM, 16-QAM, 64- QAM, and 256-QAM or other QAM, and the one or more extended constellation signals are modulated with an orthogonal frequency-division modulation; which includes reducing the peak power from the transmitting of the one or more extended constellation signals in response to the adjusting of the first data set; which includes increasing transmit diversity for the transmitting of the one or more extended constellation signals in response to the processing of the data structure and the providing of the first data set and the second data set; and/or wherein the one or more extended constellation signals are representative of at least one of audio and video information and are broadcast to a number of receivers.
  • a further embodiment is directed to an apparatus, comprising a transmitter, including: means for representing communication information with a data structure corresponding to a quadrature modulation constellation; means for processing the i data structure to represent the quadrature modulation constellation in a rotated form and provide two projection data sets each corresponding to a different projection of the rotated form; means for providing a first data set representative of a first composite constellation with a first one of the projection data sets and a second data set representative of a second composite constellation with a second one of the projection data sets; means for adjusting the first data set to represent a i first extended constellation with one or more constellation points positioned further away from one or more other constellation points relative to point positioning of the first composite constellation; and means for wirelessly transmitting one or more extended constellation signals representative of the first extended constellation.
  • a further invention example comprises: transmission circuitry including a high power
  • I amplifier and at least one antenna; and a processing device to prepare communication
  • the processing device including means for encoding the communication information in correspondence to a quadrature modulation constellation, means for providing a constellation data set representative of the quadrature modulation constellation rotated by a selected angle, means for adjusting the constellation data set to correspond to an extension of one or more constellation points away from one or more other constellation points, and means for generating corresponding output signals to the transmission circuitry.
  • the processing device includes executable programming structured to define the encoding means, the providing means, the adjusting means, and the generating means; wherein the adjusting means includes means for reducing peak power of the wireless transmission;
  • the providing means includes means for increasing transmit diversity of the apparatus; further comprising means for modulating communications in accordance with orthogonal frequency-division modulation and means for representing the communication information in a quadrature modulation constellation format selected from the group consisting of: 4-QAM, 16- QAM, 64-QAM, and 256-QAM; and/or wherein the transmission circuitry includes means for broadcasting the output signal to a number of receivers each structured to receive one or more signals, the receiver including means for reconstructing the communication information from the signals ⁇ the communication information including at least one of audio and video data.
  • Yet another invention example comprises: for transmit diversity, encoding
  • communication information into a number of composite constellation data constructs each representative of at least two projections from different rotated quadrature modulation constellations; to reduce peak transmit power, preparing a number of extended constellation data constructs each from a respective one of the composite constellation data constructs, the extended constellation data constructs each being representative of extending one or more outer constellation points away from one or more other constellation points for a respective one of the different rotated quadrature modulation constellations; and transmitting one or more signals representative of each of the extended constellation data constructs.
  • Optional variants of this example include the further inventions: wirelessly receiving the one or more signals and deriving the communication information from the one or more signals; wherein the composite constellation data constructs each correspond to a rotated constellation representation of one of a 4-QAM, 16-QAM, 64-QAM, or 256-QAM type, and the extended constellation data constructs are modulated with an orthogonal frequency-division modulation; and/or wherein the
  • transmitting includes broadcasting the one or more signals to multiple receivers, the signals representing audio-visual information.
  • Another invention example is directed to a communication device, comprising a transmitter, the transmitter including: means for increasing transmit diversity including encoding communication information into a number of composite constellation data constructs each representative of at least two projections from different rotated quadrature modulation constellations, to provide transmit diversity; means for reducing peak power including preparing a number of extended constellation data constructs each from a respective one of the composite constellation data constructs, the extended constellation data constructs each being representative of extending one or more outer constellation points away from one or more other constellation points for a respective one of the different rotated quadrature modulation constellations; and means for transmitting one or more signals representative of each of the extended constellation data constructs.
  • Still another example is directed to an apparatus, comprising: transmission circuitry including a high power amplifier and at least one antenna; and a processing device to prepare communication information for wireless transmission by the transmission circuitry, the processing device being structured to: encode the communication information in correspondence to a quadrature modulation constellation, provide a constellation data set representative of the quadrature modulation constellation rotated by a selected angle, adjust the constellation data set to correspond to an extension of one or more constellation points away from one or more other constellation points, and provide corresponding output signals to the

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Abstract

L'invention porte sur une technique de traitement de signal de communication qui consiste à coder des informations de communication en un certain nombre de constructions de données de constellation composite pour augmenter la diversité d'émission. Chacune de ces constructions est représentative d'au moins deux projections de différentes constellations de modulation en quadrature tournantes. Pour réduire la puissance de crête, un certain nombre de constructions de données de constellation étendues sont préparées, chacune à partir d'une construction respective parmi les constructions de données de constellation composite qui sont représentatives chacune d'une extension d'un ou plusieurs points de constellation extérieurs à distance d'un ou plusieurs autres points de constellation pour une constellation respective parmi les différentes constellations de modulation en quadrature tournantes. Un ou plusieurs signaux représentatifs de chacune des constructions de données de constellation étendues sont transmis. Une technique d'extension de constellation active (ACE) est combinée à des constellations tournantes (telles que 16QAM) afin d'atteindre à la fois une réduction de PAPR et une diversité spatiale de signaux.
PCT/US2010/000221 2010-01-27 2010-01-27 Techniques offrant une réduction de puissance de crête et de la diversité dans des télécommunications sans fil WO2011093834A1 (fr)

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