WO2019073029A1 - Procédé et dispositif de codage et de modulation adaptatifs - Google Patents

Procédé et dispositif de codage et de modulation adaptatifs Download PDF

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Publication number
WO2019073029A1
WO2019073029A1 PCT/EP2018/077863 EP2018077863W WO2019073029A1 WO 2019073029 A1 WO2019073029 A1 WO 2019073029A1 EP 2018077863 W EP2018077863 W EP 2018077863W WO 2019073029 A1 WO2019073029 A1 WO 2019073029A1
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ary
channel
signal constellation
constellation
geometric transformation
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PCT/EP2018/077863
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English (en)
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Farbod KAYHAN
Alireza HAQIQATNEJAD
Bhavani SHANKAR
Björn OTTERSTEN
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Université Du Luxembourg
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0002—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission rate
    • H04L1/0003—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission rate by switching between different modulation schemes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/0012—Modulated-carrier systems arrangements for identifying the type of modulation
    • 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
    • H04L27/3444—Modifications of the signal space to increase the efficiency of transmission, e.g. reduction of the bit error rate, bandwidth, or average power by applying a certain rotation to regular constellations
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0009—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the channel coding
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0023—Systems modifying transmission characteristics according to link quality, e.g. power backoff characterised by the signalling
    • H04L1/0026—Transmission of channel quality indication

Definitions

  • the present invention lies in the field of digital communications.
  • data is encoded into signals using a digital modulation technique before being transmitted from a transmitter to a receiver using a communication channel.
  • a digital modulation scheme is typically defined by a signal constellation in a complex plane or in a higher dimensional space, wherein each signal point of the constellation corresponds to a data symbol.
  • the transmitted constellation point may be retrieved using the received signal, based on the signal constellation's geometry.
  • the type and parameters of the communication channel linking the transmitter to the receiver generally has an impact on the digital modulation and coding scheme that is employed.
  • Real-time adaptation of transmission parameters according to channel conditions is one of the main features of the ever growing high-throughput communication systems. Time and/or user varying channel conditions are inherent characteristics of many communication systems such as satellite, cellular networks and broadcast systems. Adaptive Coding and Modulation, ACM, schemes are used in such systems to provide significant capacity gains by allowing the transmission format to be changed, depending on the application and/or channel quality.
  • ACM Adaptive Coding and Modulation
  • the transmitter is able to switch between several Modulation and Coding schemes, MODCODs, choosing the largest available modulation and code rate which ensures a target detection error rate, and thus providing the maximum reliable spectral efficiency to each user.
  • ACMs have been adopted in several standards such as Digital Video Broadcasting, DVB, and Consultative
  • CCSDS Committee for Space Data Systems, CCSDS, see for example " CCSDS protocols over DVB -S; Summary of definition, implementation and performance, CCSDS 130.12G-1, Nov. 2016".
  • MODCODs are predefined and known to both the transmitter and receiver nodes in a communication system.
  • Several factors affect the design of MODCODs for a given system, including the noise model (Additive White Gaussian Noise, AWGN, phase noise, etc, the channel model (fading channel, linear channel, non-linear channel, ...), the operating frequency band (Ka band, X band%), the target error rate, and the target spectral efficiency. While the coding scheme is not usually affected by these parameters, poor choice of the modulation set may result in a significant performance loss.
  • each MODCOD must be protected by a highly redundant code word in the preamble of each transmitted frame, thereby increasing the data transmission overhead.
  • Some of the current ACM schemes use over 100 MODCODs, and even higher number of MODCODs may be needed in the next generations due to higher granularity requirements, aiming at providing specific near-optimal MODCODs for a large array of communication channel parameters. Therefore the unique identifier may be large in such cases.
  • Patent document WO2017/005874 Al discloses a coding and modulation apparatus using non- uniform constellations. The use of, for example, rotated base signal constellations is described therein. However, the receiver is unaware of such geometric transformations. Technical problem to be solved
  • a method for transmitting and receiving a digital data stream over a communication channel comprises the following steps: a) at a transmitting node, modulating the data stream using modulation means to convert digital data in the data stream into symbols forming a modulated signal for transmission by transmission means, each symbol being one of M possible symbols of a first M-ary signal constellation;
  • said first M-ary signal constellation is such that there exists an M-ary base signal constellation of which the first M-ary signal constellation is a geometric transformation, and in that
  • said M-ary base signal constellation and said geometric transformation defining said first M-ary signal constellation are selected by selection means, based on channel state information.
  • a method for transmitting a digital data stream over a communication channel at a transmitting node comprises the following steps:
  • said method is remarkable in that said first M-ary signal constellation is such that there exists an M- ary base signal constellation of which the first M-ary signal constellation is a geometric transformation, and in that said M-ary base signal constellation and said geometric transformation defining said first M-ary signal constellation are selected by selection means, based on channel state information.
  • said first M-ary signal constellation and said geometric transformation may be selected exclusively based on channel state information.
  • it may be preferred that said first M-ary signal constellation and said geometric transformation may be selected based on channel state information and based on other information, preferably comprising an energy constraint.
  • both first and second information identifying respectively said selected M-ary base signal constellation and said selected geometric transformation may be transmitted from the transmitting node to the receiving node as a preamble to said modulated signal.
  • an M-ary base signal constellation may be optimized for a predetermined channel parameter value, for example for a specific value of Signal-to-Noise Ratio, SNR.
  • An M-ary base signal constellation may preferably be optimized for an AWGN communication channel.
  • said modulation means may be implemented by a processing unit coupled to a memory element and programmed to transform digital data comprised in said memory element into a modulated signal.
  • said detection means selection means may preferably be implemented by a processing unit programmed to achieve the described effect.
  • the corresponding code instructions may preferably be stored in a memory element to which said processing unit has at least read access.
  • said transmission and receiving means may comprise a networking interface configured to transmit/receive data over a communication channel.
  • Said communication channel may be a satellite link, a wireless channel or a wired channel.
  • the transmitting node may preferably transmit said modulated signal to at least one receiving node over said communication channel.
  • the transmitting node may transmit said modulated signal to a single receiving node, or to a plurality of receiving nodes.
  • information identifying said M-ary base signal constellation and said geometric transformation may be provided at the receiving node.
  • the identifying information may preferably be transmitted from the transmitting node to the receiving node as a preamble to said modulated signal.
  • At least part of said channel state information preferably information indicating a time-varying parameter of the channel, may preferably be transmitted as channel state feedback from the receiving node to the transmitting node.
  • said channel state information may comprise information indicating the type of the communication channel and information indicating a time -varying parameter of the channel, preferably the channel's signal-to-noise ratio, SNR or Bit Error Rate, BER.
  • said M-ary base signal constellation may be selected based on said information indicating a time-varying parameter of said channel, preferably SNR, and the geometric transformation may be selected based on the channel's type.
  • Said M-ary base signal constellation may preferably be a constellation having symbols distributed on a plurality of C concentric squares.
  • Said geometric transformation may further be either of a rotation about the constellation origin, or a bijective mapping of the symbols on a given square to symbols on one of an equal plurality of concentric circles.
  • said geometric transformation may preferably be a bijective mapping of the symbols on a given square of the M-ary base constellation to symbols on one of said concentric circles.
  • the coding rate may be selected by said selection means based at least partly on said channel state information.
  • the method may preferably comprise the additional step of
  • Information identifying said code may preferably be provided at the receiving node.
  • said code identifying information may be transmitted from the transmitting node to the receiving node as a preamble to said modulated signal.
  • the preamble is in the form of a data header followed of a data frame, followed by the frame's data payload comprising said modulated data-
  • a data transmission device comprising modulation means, transmission means and selection means.
  • the device is configured for
  • modulating a data stream by converting digital data in the data stream into symbols forming a modulated signal for transmission by transmission means, each symbol being one of M possible symbols of a first M-ary signal constellation;
  • the device is remarkable in that the first M-ary signal constellation is such that there exists an M- ary base signal constellation of which the first M-ary signal constellation is a geometric transformation, and in that said selection means are configured to select said M-ary base signal constellation and said geometric transformation defining said first M-ary signal constellation based on channel state information.
  • a data receiving device comprising demodulation means and reception means.
  • the device is configured for receiving a modulated signal using said receiving means, and detecting/demodulating the symbols detected in said modulated signal into said data stream.
  • the device is remarkable in that the signal constellation and coding scheme used for detecting/demodulating the symbols are selected based on information identifying a base M-ary signal constellation and a geometric transformation.
  • the M-ary signal constellation used for detecting/demodulating the symbols is said selected base M-ary signal constellation, which is transformed by said selected geometric transformation.
  • the device may be further configured for carrying out the method steps in accordance with aspects of the invention.
  • a computer program comprising computer readable code means, which when run on a computer, causes the computer to carry out at least method steps (a) and (b) or (c) and (d) according to aspects of the invention.
  • a computer program comprising computer readable code means, which when run on a computer, causes the computer to carry out the method according to any aspects of the invention.
  • a computer program product is provided.
  • the computer program product comprises a computer-readable medium on which the computer program according to previous aspects of the invention is stored.
  • the presented method can be used in any digital communication system which modulates digital data into constellation points prior to transmission.
  • Embodiments of the present invention allow to introduce a set of base Modulation and Coding schemes, MODCODs, which may for example be optimized over the AWGN channel. This set is then modified for the use over other channel models.
  • the set of base MODCODs may for example comprise optimized non-uniform QAM constellations.
  • the MODCODs over nonlinear and fading channels are related to the base set through a predetermined geometric transformation applied on the base constellations.
  • a radial mapping may be used over the non-linear channel, and the constellation rotation over the fading channel.
  • Radial constellation mappings are for example discussed by F. Kayhan, "QAM to circular isomorphic constellations," in Proc. Advanced Satellite Multimedia Syst. Conf, Palma de Alba, Spain, 2016.
  • some MODCODs are dedicated only to the linear channel and some others to the non- linear channel. These two sets of MODCODs can be merged by introducing an additional block in the communication chain.
  • these MODCODs are related to each other through a deterministic geometric transformation.
  • a radially mapped or rotated signal constellation is used at the transmitter, only the base MODCOD, as well as an indication of the respective geometric transform, need to be identified for proper decoding at the receiver. This reduces the transmission overhead while at the same time making a high number of MODCODs - all geometrically related to the base MODCODs - available for use with different channel conditions and types.
  • the invention enables a new ACM scheme which can potentially unify the MODCOD design for several existing standards. This is done by introducing a new block, called channel-adapted transformation, CAT, to the communication chain.
  • the functionality of CAT is to adapt an existing MODCOD to the given new channel condition through a deterministic geometric transformation.
  • the MODCODs designed for the linear channel can also be used over non-linear or fading channels by passing them through the CAT block.
  • Another consequence of introducing the CAT block is to reduce the number of existing MODCODs and hence reducing the length of physical layer header.
  • figure 1 illustrates the main steps according to a preferred embodiment of the method according to the invention
  • figure 2 is a schematic illustration of a data transmission device according to a preferred embodiment of the invention.
  • figure 3 is a schematic illustration of a system for implementing a preferred embodiment of the invention.
  • figure 4(a) shows part of the data frame structure as used in the DVB-S2X standard
  • figure 4(b) shows part of the data frame structure resulting from a preferred embodiment of the method according to the invention
  • FIG. 5(a)-(c) illustrates an optimized 256-QAM signal constellation and geometric transformations thereof
  • FIGS. 6(a)-(b) plot PAMI against SNR/PSNR values for various 16-ary signal constellations and for two different channel types
  • FIGS 7(a)-(b) plot PAMI against SNR/PSNR values for various 64-ary signal constellations and for two different channel types
  • FIG. 8(a)-(b) plots PAMI against SNR/PSNR values for various 256-ary signal constellations and for two different channel types
  • FIG. 10(a)-(b) plot BER against SNR/PSNR values for various 64-ary signal constellations and for two different channel types
  • FIG. 1 l(a)-(b) plot BER against SNR/PSNR values for various 256-ary signal constellations and for two different channel types;
  • FIGS. 12(a)-(c) plot BER against SNR values for various M-ary rotated and non-rotated signal constellations and for a Rayleigh fading channel. Detailed description of the invention
  • a transmitting node transmits data to at least one receiving node using a data communication channel.
  • a data communication channel may be a wireless channel, for example a satellite link.
  • a transmitting node modulates a data stream using modulation means onto a carrier wave to generate a modulated signal.
  • the modulation comprise for example a data processor programmed to convert digital data in the data stream, which is read from a memory element to which said data processor has read access, into symbols for transmission by
  • the transmission means comprise a networking interface operatively connected to the data processor.
  • Each symbol generated by the data processor is one of M possible symbols of a first M-ary signal constellation, where M is the modulation order and is in general a power two, equalling for example 16, 64, 256, etc...
  • the resulting modulated signal is put onto said communication channel using the networking interface.
  • the communication channel connects the transmitting node to at least one receiving node, which comprises receiving means such as a networking interface.
  • the networking interface of the receiving node is configured for receiving the modulated signal that was sent by the transmitting node - possibly contaminated by channel noise and/or losses.
  • Detection means which in accordance with an embodiment of the invention comprise a data processor, are programmed and configured for detecting and/or demodulating the symbols contained in the received modulated signal.
  • the first M-ary signal constellation is designed such that there exists an M-ary base signal constellation of which the first M-ary signal constellation is a geometric transformation.
  • the first M-ary signal constellation may be obtained by rotating a base signal constellation by a predetermined angle about the
  • the base signal constellation may be a non-uniform QAM signal constellation having C concentric squares on which its symbols are distributed.
  • the geometric transformation may bijectively map each symbol of a given square onto a circle associated with that square, the resulting first M-ary signal constellation comprising an equal number of C concentric circles. Other geometric transformations may be chosen without departing from the scope of the invention.
  • the base M-ary signal constellation and the transformation, both of which define the first M-ary signal constellation that is used for generating the modulated signal, are selected based on channel state information.
  • the channel state information comprises information on the channel type (linear, non-linear, fading, ...) and/or information on the channel's state, described by at least one parameter such as SNR or BER. All or part of the channel state information is obtained at the transmitting node as feedback information using a feedback channel connecting the receiving node to the transmitting node.
  • the base M-ary signal constellation and the selected geometric transformation are identified at the receiving node.
  • the receiving node is capable of detecting/demodulating the received modulated signal, and to extract the original data stream for further use by a data processor.
  • the receiving node may able to detect the used signal constellation based on a power spectral analysis of the received modulated signal.
  • the information identifying the base M-ary signal constellation and the selected geometric transformation is transmitted to the receiving node in a header or preamble to the actual modulated data stream. The preamble only needs to identify a base M-ary signal constellation, and a geometric transformation.
  • the receiving node only needs to store the base M-ary signal constellation. As this constellation is identified in the preamble, the receiving node selects it. It then applies the geometric transform, which is also identified in the preamble, to the selected base M-ary signal constellation. The resulting constructed M-ary signal constellation allows for proper detection/demodulation of the received symbols.
  • the transmitting node has access to a set of base M-ary signal constellations, each base M-ary signal constellation being optimized for a specific SNR value or value range and for an AWGN linear channel. At least part of the channel state information, for example an observed SNR value, is transmitted to the transmitting node as feedback from the receiving node. Using this observed SNR value, the transmitting node selects a corresponding M- ary signal constellation from the base set.
  • the transmitting node has knowledge of the channel type of the communication on which it transmits data, so that it selects a corresponding geometric transform and thereby identifies the M-ary signal constellation that is used for modulating the data stream. Alternatively, the channel type may also be obtained via feedback from the receiving node.
  • FIG. 2 schematically illustrates an example of a device for implementing the steps (a) and (b) outlined here above.
  • the data transmission device 10 comprises a memory element 1 1 , which may be a volatile memory for storing the data that is to be transmitted, a consistent memory element 13 in which the base and/or transformed M-ary signal constellations are stored, and modulation means 12 for modulating the data onto a carrier wave in accordance with the first M-ary signal constellation. While the consistent memory element 13 is shown to be physically collocated with the device 10, it may as well be remote to the device. In such a case, the device 10 has remote access to the networked memory resource 13 using a communication channel. The resulting modulated signal is transmitted using transmission means 14 over a communication channel 30.
  • the device 10 further comprises selection means 16. Based on channel state information, shown in Figure 2 in a non-limiting way as being obtained through channel feedback 5, the selection means determine the base M-ary signal constellation and the geometric transform that match the channel type and channel parameters best, thereby defining the first M-ary signal constellation to be used by the modulation means. In order to perform the selection, the selection means have preferably access to a look-up table stored in a memory element, which associates channel types and parameters to base constellations and geometric transforms.
  • a corresponding receiver which is not illustrated, received a noisy version of the modulated signal and demodulates/detects the symbols that have been transmitted. Using the information identifying the base MODCOD and the geometric transform that were used by the modulation means at the transmitter, the receiver is able to identify the M-ary signal constellation used to generate the modulated signal - which is the information it needs to retrieve the transmitted data from the received symbols.
  • a system model is outlined in Section 2. This is followed by defining the channel-adapted transformation block. In Section 3, a mutual information analysis for various constellations of interest is provided. Simulation results are reported in Section 4 and the Bit Error Rate, BER, of the proposed ACM scheme is compared to those of DVB-S2X and DVB-T2. 2 System Model
  • the input sequence of data bits u are first encoded to a longer sequence c in order to increase the robustness of detection against non-deterministic effects of the physical medium (e.g., wireless channel).
  • the physical medium e.g., wireless channel.
  • LDPC low- density parity check codes
  • the encoded data sequence is then mapped into symbols x with a specific constellation set ⁇ .
  • the number of bits per symbol also known as modulation order) affects the transmission bit rate. More bits per symbol ensures higher throughput, but deteriorates the accuracy of detection at the receiver if the SNR is kept fixed.
  • the same process is usually performed in reverse order at the receiver, i.e., first detecting the transmitted symbol x and then decoding the coded sequence to obtain the estimated data sequence u . Due to the stochastic nature of the channel, the knowledge of short-term or long-term status of the channel is useful to increase the reliability of the communication. Having the channel estimation, for example, the transmitter can adapt the instantaneous transmission rate and modulation order according to the current channel condition. There are several ways to adjust the transmission rate in order to have a reliable communication over a physical channel. Changing the modulation order and the coding rate are two most common mechanisms which are used in an Adaptive Coding and Modulation, ACM, system.
  • ACM Adaptive Coding and Modulation
  • a conventional ACM scheme is able to switch between a number of MODCODs as a function of the instantaneous channel state and the target spectral efficiency.
  • the MODCOD is selected based on the channel estimation at the receiver which is available to the transmitter using a finite rate feedback channel.
  • a sufficiently wide range of received SNRs is divided into several intervals, each of which is assigned a MODCOD with respect to the spectral efficiency requirements. Therefore, any given spectral efficiency is supported by changing either the number of bits per modulated symbol or the coding rate.
  • an ACM scheme that can be adapted to different channel models is proposed. This is done by first defining a set of base MODCODs and then modifying this set as a function of channel model using a deterministic geometric transformation.
  • the MODCOD set for any given channel model is related to the base MODCOD set through an additional system block, which is referred to as channel-adapted transformation, CAT.
  • the CAT block is basically a multicriteria deterministic function.
  • One of the advantages of adding the CAT block in the ACM scheme is the reduced number of required bits to distinguish all the predefined MODCODs.
  • the basic frame structure of the current DVB satellite standard is compared to the frame structure of the proposed scheme.
  • DVB-S2X some bits in the PLS header are defined to determine the MODCOD.
  • the number of allocated bits can be decreased as a result of having less number of MODCODs, while covering the same range of SNR with the same granularity. This reduction is achieved by having a base MODCOD set designed only for the linear channel and then extended to the non- linear channel through the CAT block.
  • the transmitter only has to declare the channel model (i.e., the functionality of the CAT block) once at the beginning of the transmission of the superframe. This can be considered as an initialization step and is depicted by the CAT header in Figure 4.
  • the length of the CAT header depends on the number of functions defined in the CAT block. For example, for a two-mode unified ACM system (e.g., operating over linear and non-linear channel models), only one bit per superframe is needed for this one-time header.
  • CAT block is just a systematic way to distinguish between the MODCODs designed for different channel models or conditions.
  • the channel model is fixed during the frame (or superframe) time, one may define a header similar to the CAT header to indicate the channel model without specifically going to the CAT block.
  • all the MODCODs are defined off-line but only a portion of them is used at any given frame (or superframe).
  • the first step in designing the unified ACM framework in accordance with the invention is to find a base MODCOD set. Only the modulation scheme to be used in each MODCOD is defined in this preferred embodiment, and therefore the coding scheme is not changed. In alternative
  • the coding scheme may also be varied as a function of the channel state information available at the transmitter.
  • the MODCODs in DVB-S2X and DVB-T2 standards cannot be interchangeably used without a substantial loss in one or the other system.
  • the DVB-S2X standard mainly adopts APSK constellations in the MODCODs targeted for non-linear channels. In general, APSK constellations are not optimal over linear channels. Therefore, some MODCODs in DVB-S2X are specifically designed for use over linear channels.
  • DVB-T2 uses QAM constellations in its MODCODs, but it is well known that the QAM signaling leads to noticeable performance loss over non-linear channels. The opposing performance of these MODCODs over different channel models leads the inventors to design channel-adapted MODCODs with competitive performance over both linear and non- linear channels.
  • Non-uniform QAM constellations have been studied by several authors due to their potential shaping gain and higher mutual information with respect to the conventional uniform QAM over the AWGN channel - see for example B. Mouhouche, D. Ansorregui, and A. Mourad, "High order non-uniform constellations for broadcasting UHDTV, " in Proc. IEEE Wirel. Commun. and Netw. Conf, Istanbul, Turkey, 2014, and references cited therein. These constellations also allow for a low complexity detection, as they can be obtained by the Cartesian product of two non-uniform pulse amplitude modulation, PAM, constellations. This family of QAM constellations is considered to be employed in ATSC 3.0 broadcasting standard as outlined in "ATSC Standard, Physical Layer Protocol, Doc.
  • non-uniform QAM constellations obtained by optimization over the linear AWGN channel, are used as the set of base MODCODs. These constellations are referred to as non-uniform (NU) QAM for simplicity.
  • NU non-uniform
  • a simulated annealing algorithm is used to perform ID optimization at any given SN, as discussed in F. Kayhan and G. Montors, "Constellation design for memoryless phase noise channels, " IEEE Trans. Wirel.
  • the next step is to define the functions in the CAT block in order to obtain the MODCODs for other channel models.
  • a class of circular constellations has been introduced in F. Kayhan, "QAM to circular isomorphic constellations," in Proc. Advanced Satellite Multimedia Syst. Confi, Palma de Tempe, Spain, 2016.
  • the proposed constellation exhibit achievable mutual information being very close to the peak-power limited channel capacity.
  • This type of constellations named QCI, is in fact the transformation of QAM points under the radial isomorphism, which converts the concentric squares into concentric rings.
  • Let (u,v) £ denote a QAM constellation point, then the radial mapping is defined as
  • the radial mapping in Eq. (1) can also be applied to NU QAM signal set.
  • the result will be a QCI constellation with concentric rings of non-uniform radii (see Figure 5(b)). Even though the resulting QCI constellations are not optimal over the non-linear channel, as will be outlined in Section 3, they perform very close to the state of the art. These signal constellations as NU QCI in the remainder of the present description.
  • Such a CAT block enables the base MODCOD set to be adapted to use over non-linear and fading channels by a simple geometric transformation of symbols. This will not only reduce the number of MODCODs needed but also allow for lower transmitter and receiver complexities and decrease the amount of MODCOD signaling overhead.
  • the definition in Eq. (3) can be regarded as one possible realization of the unified ACM scheme; in general, one may define extra criteria to extend the compatibility of CAT with a diverse range of wireless applications.
  • BICM bit- interleaved coded modulation
  • BICM capacity also known as pragmatic average mutual information PAMI, which is defined as follows:
  • ⁇ and x are respectively the constellation set and its constituting points
  • ⁇ is the symbol labeling with ⁇ '( ⁇ ) representing the z ' -th bit of the label assigned to x
  • y denotes the received signal at the output of the channel.
  • the mutual information of a number of possible MODCODs in the proposed unified ACM in accordance with embodiments of the invention are compared with some of the MODCODs used in DVB-S2X and DVB-T2 standards, where PAMI is plotted versus SNR (linear channel) and PSNR (non-linear channel).
  • the PAMIs over the non-linear channel are compared with the capacity of peak-power constrained channels derived by Shamai et al. in "The capacity of average and peak-power-limited quadrature Gaussian channels," IEEE Trans. Inform. Theory, vol. 41, no. 4, pp. 1060- 1071, Jul. 1995.
  • M 16
  • M 64
  • M 256 points optimized for target SNRs of 10 dB, 15 dB and 20 dB, respectively.
  • DVB-S2X MODCOD designed for the same range of SNR (or PSNR) with highest PAMI over the linear (or nonlinear) channel is considered.
  • 64-APSK 132/180 refers to the MODCOD designed for the non- linear channel with LDPC code identifier 132/180
  • 64-APSK 128/180-L is the MODCOD designed for the linear channel with LDPC code identifier 128/180.
  • Figure 6 compares the PAMI of various constellations with 16 points.
  • the linear channel in Figure 6(a) there is a slight difference (always below 0.05 bits/symbol in the depicted range of SNR) between the PAMI of 16-APSK 20/30-L constellation and that of NU 16-QAM.
  • NU 16-QAM has higher PAMI than 16-QAM which is clearly the result of optimization over the linear AWGN channel.
  • Table I the results are summarized in Table I.
  • Table I the comparison of the sum capacity gap and the overall loss with respect to the capacity limits for four different MODCOD pairs is presented.
  • the sum capacity gap is obtained by adding the PAMI loss of the linear MODCOD with respect to the Shannon limit and the PAMI loss of the non-linear MODCOD with respect to the Shamai limit for a given SNR value.
  • the Overall loss is computed by adding the SNR loss of linear and non- linear MODCODs with respect to the corresponding capacity limits for a fixed value of PAMI.
  • Table I the best result is obtained by selecting two different MODCODs
  • Table I Numerical comparison of sum capacity gap and overall loss for the MODCODs with 16- ary constellations.
  • Table II Numerical comparison of sum capacity gap and overall loss for the MODCODs with 64- ary constellations.
  • MODCOD achieves about 0.1 bits/symbol higher PAMI than NU 256-QAM. Over the non-linear channel, 256-APSK 135/180 and NU 256QCI both achieve the same PAMI in the desired SNR range, as shown in Figure 8(b).
  • 256-APSK 135/180 and NU 256QCI both achieve the same PAMI in the desired SNR range, as shown in Figure 8(b).
  • employing the CAT-related MODCODs of the unified ACM does not lead to significant performance loss in terms of achievable spectral efficiency.
  • Table III The numerical comparison of the four MODCOD pairs is shown in Table III. The overall conclusion is similar to the previous cases; the loss due to using the CAT scheme is about 0.27 dB when compared to the 2-MODCOD DVB-S2X scenario.
  • the Bit Error Rate, BER, simulation results are shown for all the constellations analyzed in the previous section.
  • the results are obtained over various channel models according to DVB-S2X and DVB-T2 scenarios.
  • DVB-S2X the simulations are performed over both linear and non-linear channels. Comparisons under the DVB-T2 scenario are drawn assuming an i.i.d Rayleigh fading channel.
  • Table III Numerical comparison of sum capacity gap and overall loss for the MODCODs with 256-ary constellations.
  • NU 16-QAM MODCOD refers to the combination of NU 16-QAM and the selected LDPC code with rate 3/4.
  • Figure 9 compares the BER performance of various MODCODs that use 16-ary constellations. As it can be seen in Figure 9(a), the performance of NU 16-QAM over the linear channel is quite close to 16-APSK 20/30-L and superior to 16-QAM. Over the non-linear channel ( Figure 9(b)), NU 16- QCI shows a slight loss (less than 0.1 dB) with respect to 16-APSK 13/18 MODCOD. One can further observe that the difference between NU 16-QCI and 16-QCI is insignificant.
  • the BER curves are plotted in Figures 10(a) and 10(b) for linear and non-linear channels, respectively. As before, the BER simulations confirm closely the PAMI results. A loss of 0.1 dB is resulted from using NU 64-QAM compared to 64-APSK
  • FIG. 1 The BER performance of various MODCODs with 256-ary constellations is depicted in Figure 1 1.
  • NU 256-QAM MODCOD shows a performance loss of about 0.25 dB compared to 256-APSK 22/30-L, but a gain of 0.5 dB against the uniform 256-QAM.
  • Figure 1 1(b) shows that NU 256-QCI performs around 0.1 dB better than the best DVB-S2X non-linear MODCOD in this SNR range (256-APSK 138/180). It follows from the BER results that the CAT-related MODCODs provide competitive performance with respect to the separate linear and non- linear MODCODs of DVB-S2X, which is in line with the PAMI results obtained in the previous section.
  • the BER results show that NU QAM performs better than QAM over fading channels for all the constellation sizes of interest.
  • the BER of the best linear DVB-S2X MODCOD for each constellation size has also been simulated. All the considered DVB-S2X linear MODCODs show a loss with respect to both QAM and NU QAM, even if RQD is employed.
  • the cyclic Q-delay without constellation rotation has been aplied. The BER results in that case were slightly worse than those obtained with RQD, and thus are not presented here.

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Abstract

L'invention concerne un procédé et un dispositif de codage et de modulation adaptatifs dans lequel une constellation de signaux de base est transformée puis utilisée pour moduler un flux de données. La constellation de signaux de base et la transformation sont déterminées par les informations d'état de canal, comprenant un modèle de canal et des paramètres de canal.
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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113132290A (zh) * 2021-04-23 2021-07-16 焦作大学 一种信号调制装置及其调制方法
CN114567530A (zh) * 2022-04-27 2022-05-31 华中科技大学 一种信道信噪比自适应的油气井无线通信方法
WO2022252952A1 (fr) * 2021-06-02 2022-12-08 中兴通讯股份有限公司 Procédé de transmission de données, dispositif et support de stockage
WO2023239916A1 (fr) * 2022-06-10 2023-12-14 Hughes Network Systems, Llc Constellation adaptative pour transmodulation dans des systèmes de communication par satellite

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017005874A1 (fr) 2015-07-09 2017-01-12 Sony Corporation Appareil de codage et de modulation utilisant une constellation non uniforme
WO2017202823A1 (fr) * 2016-05-24 2017-11-30 Université Du Luxembourg Procédé et dispositif d'émission de données utilisant des constellations apsk non uniformes

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017005874A1 (fr) 2015-07-09 2017-01-12 Sony Corporation Appareil de codage et de modulation utilisant une constellation non uniforme
WO2017202823A1 (fr) * 2016-05-24 2017-11-30 Université Du Luxembourg Procédé et dispositif d'émission de données utilisant des constellations apsk non uniformes

Non-Patent Citations (13)

* Cited by examiner, † Cited by third party
Title
"CCSDSprotocols over DVB-S; Summary of definition, implementation and performance", CCSDS 130.12G-1, November 2016 (2016-11-01)
"Digital Video Broadcasting (DVB)Part II: DVBS2-Extensions (DVB-S2X))", DVB-S2X, SEE ETSI 302-307-2, 2014
ATSC STANDARD, PHYSICAL LAYER PROTOCOL, June 2017 (2017-06-01)
B. MOUHOUCHE; D. ANSORREGUI; A. MOURAD: "High order non-uniform constellations for broadcasting UHDTV", PROC. IEEE WIREL. COMMUN. AND NETW. CONF., 2014
F. KAYHAN: "QAM to circular isomorphic constellations", PROC. ADVANCED SATELLITE MULTIMEDIA SYST. CONF., 2016
F. KAYHAN; G. MONTORS: "Constellation design for memoryless phase noise channels", IEEE TRANS. WIREL. COMMUN., vol. 13, no. 5, May 2014 (2014-05-01), pages 2874 - 2883, XP011548060, DOI: doi:10.1109/TWC.2014.040714.130731
G. CAIRE; G. TARICCO; E. BIGLIERI: "Bit-interleaved coded modulation", IEEE TRANS. INFORM. THEORY, vol. 44, no. 3, May 1998 (1998-05-01), pages 927 - 946, XP011027046
H. MERIC: "Approaching the Gaussian Channel Capacity With APSK Constellations", IEEE COMMUN. LETT., vol. 19, no. 7, July 2015 (2015-07-01), pages 1125 - 1128, XP011662607, DOI: doi:10.1109/LCOMM.2015.2431674
J. BOUTROS; E. VITERBO: "D VB- T2: Signal space diversity: A power- and bandwidth-efficient diversity technique for the Rayleigh fading channel", IEEE TRANS. INFORM. THEORY, vol. 44, no. 4, July 1998 (1998-07-01), pages 1453 - 1467, XP003001157, DOI: doi:10.1109/18.681321
J. BOUTROS; E. VITERBO: "DVB-T2: Signal space diversity: A power- and bandwidth-efficient diversity technique for the Rayleigh fading channel", IEEE TRANS. INFORM. THEORY, vol. 44, no. 4, July 1998 (1998-07-01), pages 1453 - 1467
J. ZOELLNER; N. LOGHIN: "Optimization of high-order non-uniform QAM constellations", PROC. IEEE INT. SYMP. BROADBAND MULTIMEDIA SYST. AND BROADCASTING, 2013
N. LOGHIN ET AL.: "Non-uniform constellations for ATSC 3. 0", IEEE TRANS. BROADCASTING, vol. 62, no. 1, March 2016 (2016-03-01), pages 197 - 203, XP011608957, DOI: doi:10.1109/TBC.2016.2518620
SHAMAI ET AL.: "The capacity of average and peak-power-limited quadrature Gaussian channels", IEEE TRANS. INFORM. THEORY, vol. 41, no. 4, July 1995 (1995-07-01), pages 1060 - 1071, XP055107950, DOI: doi:10.1109/18.391243

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113132290A (zh) * 2021-04-23 2021-07-16 焦作大学 一种信号调制装置及其调制方法
WO2022252952A1 (fr) * 2021-06-02 2022-12-08 中兴通讯股份有限公司 Procédé de transmission de données, dispositif et support de stockage
CN114567530A (zh) * 2022-04-27 2022-05-31 华中科技大学 一种信道信噪比自适应的油气井无线通信方法
WO2023239916A1 (fr) * 2022-06-10 2023-12-14 Hughes Network Systems, Llc Constellation adaptative pour transmodulation dans des systèmes de communication par satellite

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