• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
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    • 专利摘要:
    The invention relates to a mode selection method for a MIMO transmission system on a multi-mode optical fiber. It comprises a step of measuring the transfer matrix of the transmission channel constituted by a set of modes of the optical fiber (110), a step of transformation (120) of the transfer matrix into a diagonal matrix by blocks, each block being associated with a subset of modes, a step (130) of determining the gain and / or the transmission capacity for each of the subsets of modes, and a selection (140) of the subset of modes corresponding to the gain and / or the highest capacity (e), the MIMO transmission system then using only the modes of the subset thus selected to transmit on the optical fiber. The invention also relates to a method for selecting cores for a multi-core optical fiber MIMO transmission system.
    公开号:FR3025676A1
    申请号:FR1458379
    申请日:2014-09-08
    公开日:2016-03-11
    发明作者:Elie Awwad；Othman Ghaya Rekaya-Ben；Yves Jaouen
    申请人:Telecom ParisTech；
    IPC主号:
    专利说明:

    [0001] TECHNICAL FIELD The present invention relates generally to the field of optical telecommunications and more particularly to those using optical fibers of the multi-mode type. BACKGROUND OF THE INVENTION or multi-heart. STATE OF THE PRIOR ART Long-distance optical transmissions (a few hundred to a few thousand kms) use single-mode optical fibers. These have the advantage of not having any modal dispersion (apart from the polarization mode dispersion) and of being able to withstand high rates of several tens of Gbits / s per wavelength, and this for a plurality of lengths. 'wave. However, for short-distance transmissions, especially for wideband local area networks (LANs), multimode or multi-core fibers are a particularly interesting alternative to single-mode fibers. Multi-mode fibers are currently available in the form of plastic fibers (or POFs) or silica fibers. The multi-mode fibers have a large diameter core allowing the propagation of several guided spatial modes, denoted LPep for a linear polarization where is the azimuthal mode index and p the radial mode index. The LPoi mode is the fundamental mode, the only mode that can be propagated in a single-mode fiber. The total number of LP modes depends on the optogeometric parameters (core diameter, index profile). In addition, for each LPep spatial mode, two orthogonal polarization states can be defined. The information to be transmitted is distributed over the various guided modes (and, where appropriate, over the different polarizations of these modes). When the number of guided modes is low, it is called low-multi-mode optical fiber. More precisely, an optical fiber is said to be weakly multi-mode if its normalized frequency parameter V is such that V <8.
    [0002] The capacity of the multimode fibers is generally greater than that of the monomode fibers, each mode being separately modulated and the signal to be transmitted being multiplexed on the different modes. This capacity is, however, limited by the coupling between L.ep modes during propagation (inter-mode cross-talk). Multi-core fibers comprise a plurality of cores (typically 2 to 7 hearts) within a common sheath. The size of the cores is generally small enough to allow only one-mode propagation in each of them. In this case, they do not exhibit modal dispersion. On the other hand, the evanescent waves create a coupling between the different cores (inter-heart crosstalk), the level of crotch is all the higher as the number of cores is high and the inter-heart distance is small. Like the inter-mode coupling discussed above, inter-core coupling limits the scope of these systems. MIMO (Multiple Input Multiple Output) techniques can be implemented to separate the transmission on the different modes or different cores and thus increase the transmission capacity, like diversity multi-antennal wireless telecommunication systems. Space. A description of a multimode optical fiber MIMO optical transmission method can be found in the article by S. Randel et al. entitled "6x56 Gb / s mode-division multiplexed transmission over 33-km few-mode fiber enabled by 6x6 MIMO equalization" published in Opt. Express 19, 16697-16707 (2011).
    [0003] More recently, application FR-A-2977099 in the name of the present applicant has proposed using a spatio-temporal coding to transmit symbols on a plurality of modes (in a weakly multi-mode fiber) or cores. This technique makes it possible to substantially reduce the bit error rate with respect to the uncoded MIMO optical transmission system, mentioned above.
    [0004] However, MIMO optical transmissions, with or without spatio-temporal coding, on multi-mode or multi-core type fibers, are complex to implement for a large number of modes / cores, the complexity of the treatment to the varying reception, depending on the decoding type, at best in O (M3) where M is the number of modes / cores of the fiber.
    [0005] In addition, the treatment in question requires M RF chains in parallel, which in turn increases the cost of transmitters / receivers. To reduce both processing complexity and costs, it is necessary to select the modes / hearts by which the transmission will be performed. The object of the present invention is to provide an original mode selection method in multi-mode / core fiber in multi-core optical fiber for a MIMO optical transmission system. DISCLOSURE OF THE INVENTION The present invention is defined by a mode selection method for a multi-mode optical fiber MIMO transmission system comprising: (a) a step of measuring the transfer matrix of the transmission channel consisting of a set of modes of said optical fiber; (b) an operation of transforming said transfer matrix into a block diagonal matrix, each block relating to a subset of modes of said optical fiber; (c) a step of determining a gain and / or a transmission capacity (130) for each of the subsets of modes associated with said blocks; (d) a step of selecting the subset of modes corresponding to the gain and / or the highest capacity (e), the MIMO transmission system then using only the modes of the subset thus selected to transmit on said fiber optical. The transformation of the transfer matrix advantageously comprises a thresholding step in which all the elements of the matrix lower than a predetermined threshold value are set to zero, followed by a reorganization step of the transfer matrix thus obtained. by permutating its rows and columns, the permutations on the rows and those on the columns being identical. According to a first variant, the subset of modes is selected according to the gain criterion nopt = argmax (yn) where yn Tr (HnlinH), N being the number of sub-n = 1,, N 5 sets of modes, Hn being the transfer matrix of the reduced transmission channel to the modes of the subset n, HH being the conjugated transposed matrix of Hn and Tr (.) being the trace function. According to a second variant, the subset of modes is selected according to the (where yn = Tr (linlinH), where N is the number of sub-criteria of gain nopt = argmax n = 1,, N Mn 10 sets of modes, Mn being the cardinal of the subset n, Hn being the transfer matrix of the reduced transmission channel to the modes of the subset n, HH being the conjugated transposed matrix of Hn and Tr (.) being the trace function. , the subset of modes is selected according to a Mn (, Mn being the cardinal criterion of capacity nopt = arg max (Cn)) where Cn = Ilog 1+ y 'n MN n = 1, .., N m = 1 , n 0/15 of the subset n, where y is the transmission channel gain on the m mode of the subset n, where Pe is the distributed transmit power on the Mn modes and No is the noise power at In a fourth variant, the subset of modes is selected according to a hybrid criterion of gain and of capacity nopt = argmax (cD ( Cn, yn)) where Cn is the capacity n = 1,, N 2 0 of the reduced transmission channel to the modes of the subset n,) where Hn is the transfer matrix of the reduced transmission channel to the modes of the subset n, HH being the conjugated transposed matrix of Hn and Tr (.) being the trace function, and where 1 (.,.) is an increasing function of Cn and yn.
    [0006] Following the selection of the subset of modes, the degree of modulation of the symbols to be transmitted on the different modes may be chosen equal to a value Q 'such that M' log Q '= M log Q where M is the cardinal of all the modes before selection, M 'is the cardinal of the selected subset of modes and Q is the degree of modulation of the symbols to be transmitted before the selection of the subset of modes. Alternatively, following the selection of the subset of modes, the degree of modulation of the symbols to be transmitted on the different modes is chosen different for the different modes of the subset of modes. Finally, the symbols to be transmitted may be subjected to space-time coding, the elements of the space-time code being then transmitted only on the modes of said selected subset of modes. The invention also relates to a method for selecting cores for a multi-core optical fiber MIMO transmission system comprising: (a) a step of measuring the transfer matrix of the transmission channel constituted by a set of cores of said fiber optical; (b) transforming said transfer operation into a block diagonal matrix, each block relating to a subset of cores of said optical fiber; (c) a step of determining a gain and / or a transmission capacity for each of the subsets of cores associated with said blocks; (d) a step of selecting the subset of cores corresponding to the gain and / or the highest capacity (e), the MIMO transmission system then using only the cores of the subset thus selected to transmit on said optical fiber .
    [0007] The transformation of the transfer matrix advantageously comprises a thresholding step in which all the elements of the matrix lower than a predetermined threshold value are set to zero, followed by a reorganization step of the transfer matrix thus obtained. by permutating its rows and columns, the permutations on the rows and those on the columns being identical.
    [0008] According to a first variant, the subset of cores is selected according to the gain criterion nopt = argmax (yn) where yn = Tr (HnlinH), N being the number of sub-n = 1,, N sets of cores , Hn being the transfer matrix of the reduced transmission channel at the core of the subset n, HH being the conjugated transpose matrix of Hn and Tr (.) Being the trace function. According to a second variant, the subset of cores is selected according to the (where yn = Tr H, N being the number of sub-criteria of gain nopt = argmax n = 1, .., N Mn sets of cores, Mn being the cardinal of the subset n, Hn being the transfer matrix of the reduced transmission channel at the cores of the subset n, HH being the conjugated transposed matrix of Hn and Tr (.) being the trace function. , the subset of cores is selected according to one, Mn being the cardinal M (the heart m of the sub-criterion of capacity n pt = arg max (Cn) where Cn = log 1+ n = 1, .., N m = 1 of the subset n, y being the gain of the transmission channel yin, mnNo, on set n, Pe being the distributed transmit power on the Mn cores and No being the power of noise on reception on a core According to a fourth variant, the subset of cores is selected according to a hybrid criterion of gain and of capacity nopt = argmax (cD (Cn, yn)) where Cn is the capacity n = 1,, N of the reduced transmission channel at the core of the subset n, yi, = Tr (HnHnH) where Hn is the transfer matrix of the reduced transmission channel at the core of the subset 20 n, HH being the conjugated transposed matrix of Hn and Tr (.) being the trace function, and where 1 (.,.) is an increasing function of Cn and yn. Following the selection of the subset of cores, the degree of modulation of the symbols to be transmitted on the different cores can be chosen equal to a value Q 'such that M' log Q '= M log Q where M is the cardinal of the all of the cores before selection, M is the cardinal of the selected subset of cores and Q is the degree of modulation of the symbols to be transmitted before selecting the subset of cores. Alternatively, following the selection of the subset of cores, the degree of modulation of the symbols to be transmitted on the different cores can be chosen different for the different cores of the subset. Advantageously, the symbols to be transmitted are subject to spatio-temporal coding, the elements of the space-time code being then transmitted only on the cores of said selected subset of modes.
    [0009] BRIEF DESCRIPTION OF THE DRAWINGS Other features and advantages of the invention will be apparent from the reading of preferred embodiments of the invention, with reference to the appended figures in which: FIG. 1 schematically illustrates a mode selection method for a multi-mode optical fiber MIMO transmission system according to a first embodiment of the invention; Fig. 2 schematically represents a method for selecting cores for a multi-core optical fiber MIMO transmission system, according to a second embodiment of the invention.
    [0010] DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS We will first discuss the invention in the case of a multi-mode optical fiber MIMO transmission system. In such a system, the symbols to be transmitted at a given instant are multiplexed over a plurality of M modes of the fiber (and where appropriate for a given mode on two different polarizations). On reception, the signals received on the different modes are provided for example by a maximum likelihood detector (ML) for estimating the transmitted symbols. The transmission channel constituted by the M modes of the optical fiber can then be modeled by: Y = HX + N (1) where X is a vector of size M whose elements are the transmitted complex symbols, 5H is a matrix of size MxM representing the function of the transmission channel and called the transfer matrix of the channel, Y is a vector of size M representative of the complex signals received on the different modes and N is a vector of size M whose elements are samples of supposed noise white additive Gaussian and variance No by mode.
    [0011] The multi-mode fiber comprises in fact a plurality L of sections, an amplifier being provided between each pair of consecutive segments. Each fiber section can be conceptually divided into K consecutive sections, the characteristics of the fiber being stationary along the length of each section. The transfer matrix on each section can be obtained by a matrix product TÆkRÆkoù 1: t, ek, of size MxM, is the coupling matrix between modes, relative to the section k of the section L, and Te k is a diagonal matrix , also of size M xM, whose diagonal elements give the respective phase shifts of the different modes on the section k of the section L. Each coupling matrix 1: t, ek can be modeled as an orthogonal random matrix (1Z, ek.R ,, Tk = lm where Im is the identity matrix), which reflects the conservation of the distributed energy over the different modes. The non-diagonal coefficients of the coupling matrix are the coupling coefficients between modes. Their values depend on the overlapping integrals of the field distributions between the different modes propagating in the section of the section in question. The overlay integrals themselves depend on the imperfections and curvature of the fiber section in this section. The matrix Te k is a matrix whose diagonal coefficients are of the form eek OÙ 912k is the result of the drawing of a random variable uniformly distributed on [0,24.
    [0012] Finally, the amplifier between two sections £ and £ + 1 can be modeled by a gain matrix G. More precisely G, e is a diagonal matrix of size M xM whose elements give the respective gains of the amplifier for the different modes. The matrix G, e may be represented by the product of a mean gain (scalar) with an offset matrix around this gain. Finally, the transfer matrix of the transmission channel can be expressed in the form: LIK (2) H = fJ G, H (T ,, k ,, k = 1, the product over k being relative to a same section and the product on £ being relative to the same section In practice, the matrix H brings out subsets of modes, the modes belonging to the same subset being coupled together and the modes belonging to in other words, the coupling of modes only plays a significant role in subsets of specific modes. by subassembly, for example by performing permutations on the lines and corresponding permutation on the columns of the transfer matrix of the transmission channel, H, we obtain a diagonal matrix in blocks, that is to say presenting the following form: (111 0 --- 0 0 H, - .-.
    [0013] Where the matrices (or blocks) Hn, n = 1, ..., N are square matrices of sizes Mn xMr, such that IMn = M. Terms outside the diagonal Hn blocks are represented in n = 1 (3) as zero but in practice they may be simply below a minimum threshold coupling.
    [0014] The idea underlying the invention is to select on transmission, a subset of modes corresponding to one of the blocks Hn, n = 1,..., N, among the M modes of the fiber. This selection is advantageously performed according to a gain criterion and / or a capacity criterion, as described below. At the reception, it will be possible to use only the subset of selected modes or a superset of the latter, or even all 10 modes, to decode the information. Indeed, it may be interesting to retrieve information in modes that, although not selected and therefore not used by the issuer, contain information, the choice being made according to a compromise criterion between performance and complexity. . The gain criterion can be considered according to different variants. The term gain is to be understood here in its broadest sense, since the gain value may be less than 1. If it is assumed that the transmission of the symbols is effected by means of the modes associated with the block Hn, the power gain can be expressed by: 20 yn = Tr (linlinH) (4) According to this variant, the gain values, yr, are calculated for the different subsets n = 1, ..., N and the nopt subset is used to obtain the maximum gain (the minimum loss): 25 nopt = arg max) (5) n = 1, .., N 3025676 11 According to another variant, it is possible to select the subset of modes for which the average gain per mode is the highest, in other words: n0 r = arg max P n = 1, .., N Mn 5 Other variants may alternatively be considered by those skilled in the art without departing from the scope of the invention. The matrices HnHnH, n = 1, ..., N being diagonalizable and their eigenvalues being real and positive, denoted yn, m = 1, ..., Mn, for the matrix HnHnH, it will be possible to use other functions of gain that the M 'sum of the eigenvalues given in (4), for example their product nym (or, of m = 1 equivalent way, Ilog y: 1). m = 1 The second selection criterion is a capacity criterion. If it is assumed that the transmission of the symbols is carried out by means of the modes associated with the block Hn, the capacity of the channel, assumed to be linearly responsive, is given by: 11.4 1 Cn = log 1+; 'm = 1 Mn1 10) (7) where Pe is the total transmission power distributed over the Mn modes. The ratio ym MnNo 20 represents the signal-to-noise ratio at reception on the m mode. At a high signal-to-noise ratio, the channel capacity can be approximated by: (n (6) Cn = Mn log (11.4 (8) + 11og (7.7) it / InNo) m = 1 3025676 12 We can then choose the subset of nut modes to obtain the maximum transmission capacity, ie: nopt = arg max (C '(9) n = 1, .., N Finally, we can use a criterion of hybrid selection based on both the gain and the transmission capacity, in which case the subset of nopt modes satisfying this criterion is given by: 10 nopt = arg max (c (Cn, yn)) (10 n = 1, .., N where (13 is an increasing function of Cn and yn) This function could be, for example, a linear or non-linear combination of Cn and yn, the weighting coefficients depending on the priority that is If we wish to attribute to the transmission capacity and the gain, whatever the criterion chosen, the above-mentioned method of selection makes it possible to reduce the number of modes from M to noP. This is done at a constant useful rate by increasing the degree of modulation of the transmitted symbols. More precisely, if Q were the cardinal of the modulation alphabet before reduction of the number of modes, it will be possible to choose a cardinal modulation alphabet Q 'such that: M' log Q 'M log Q (11) 25 For example if the initial number of modes is M = 6 with a 4-QAM modulation one can use an 8-QAM modulation on M '= 4 modes or a 16-QAM modulation on M' = 3 modes. The increase in the degree of modulation is necessarily accompanied by a corresponding performance degradation in terms of bit error rate (BER). It is then possible to compensate for this degradation by using spatio-temporal coding as described in application FR-A-2977099 cited in the introductory part. In general, in the case where spatio-temporal coding is implemented, the symbols are transmitted in blocks, a block of symbols being transmitted over a transmission interval (TTI), using a matrix of spatio-temporal code, C, whose lines correspond to the different modes and the columns to successive uses of the channel (channel uses) during the transmission interval. Spatiotemporal coding makes it possible to combat the disparities of gain that may exist within the selected subset of modes. Fig. 1 represents a flowchart of a mode selection method for a multi-mode optical fiber MIMO transmission system, according to a first embodiment of the invention.
    [0015] It is important to note that this selection can be made once and for all, at the time of installation of the system or receiver. Alternatively, if a return path is provided to the transmitter, this selection can be made periodically, to take account of drift / aging or replacement of components (amplifiers in particular), the index itp, then being transmitted on this channel 20 by the receiver. In any case, the selection method comprises in a first step, 110, a measurement of the transfer matrix of the transmission channel, H, on a set of modes, or even all modes of the optical fiber. The measurement of the transfer matrix can be carried out, in a manner known per se, by means of pilot symbols transmitted by the transmitter. In step 120, the transfer matrix H is transformed into a diagonal block matrix. This transformation can include a thresholding of the elements of the matrix. For example, all (complex) elements of the matrix whose module is less than a predetermined threshold are set to zero. If, after thresholding, the matrix does not have a diagonal block structure, the rows and columns of the matrix are reorganized so as to group the modes into subsets of modes. The subsets of modes are such that the modes belonging to the same subset are coupled together and the modes belonging to distinct subsets are not coupled. The reorganization consists of making a series of permutations on the rows and columns, the permutations on the rows and the columns being identical (H is a square matrix). In step 130, a gain and / or transmission capacity is determined for each of the subsets of modes associated with the blocks of the transfer matrix. In other words, the values yr,, and / or Cri n = 1, ..., N are calculated as explained previously.
    [0016] In step 140, the subset of modes corresponding to the gain and / or the highest capacity (e) in the sense of a predetermined criterion is selected, for example according to one of the criteria (5), ( 6), (9) or (10). The MIMO transmission system then uses only the subset of modes selected to transmit the symbols.
    [0017] If necessary, this reduction in the number of modes may be accompanied by a corresponding increase in the degree of modulation of the symbols to be transmitted, or even a spatio-temporal coding as previously described. The degree of modulation may furthermore be chosen different for the different modes. It will be understood that a degree of modulation may in particular be chosen all the higher for a mode that the signal / noise ratio received on this mode will itself be higher. The second embodiment of the invention relates to a method for selecting cores for a multi-core optical fiber MIMO transmission system. The presentation made for the subset selection of modes will not be fully repeated for reasons of brevity. However, it will be clear to those skilled in the art that the couplings between cores in a multi-core fiber will have to be treated in the same way as the couplings between modes of a multi-mode fiber. Only the general presentation of the heart selection method will be described in connection with FIG. 2.
    [0018] As for the selection of modes of FIG. 1, the selection of cores according to FIG. 2 can be performed once and for all, during the installation of the system, or periodically and adaptively, if the system has a return path. The selection method comprises in a first step, 210, a measurement of the transmission channel transfer matrix, H, on a set of cores of the multi-core fiber, preferably on all the cores of this fiber. Here again, the transfer matrix can be measured in a manner known per se, by means of pilot symbols transmitted by the transmitter. In step 220, the transfer matrix H is transformed into a diagonal matrix 10 in blocks. This transformation can include a thresholding of the elements of the matrix and a reorganization of the modes into subsets by permutations of the rows and columns. The subsets of cores are such that the cores belonging to the same subset are coupled together and the cores belonging to distinct subsets are not coupled.
    [0019] In step 230, a gain and / or transmission capacity is determined for each of the subsets of the cores associated with the blocks of the transfer matrix. In other words, we calculate the values yr,, and / or Cri n = 1, ..., N as explained above, the calculations on the hearts instead of modes of the fiber. In step 240, the heart subset corresponding to the gain 20 and / or the highest capacity (e) is selected in the sense of a predetermined criterion, for example according to one of the criteria (5), ( 6), (9) or (10). The MIMO transmission system then uses only the subset of cores selected to transmit the symbols. Finally, this reduction in the number of cores may be accompanied by a corresponding increase in the degree of modulation of the symbols to be transmitted, or even a spatio-temporal coding as previously described. As in the first embodiment, the degree of modulation may be chosen different for the different cores, depending on the signal-to-noise ratio on each of these cores.
    权利要求:
    Claims (18)
    [0001]
    REVENDICATIONS1. A mode selection method for a multi-mode optical fiber MIMO transmission system comprising: (a) a step of measuring (110) the transmission channel transfer matrix consisting of a set of modes of said optical fiber; (b) transforming (120) said transfer matrix into a block diagonal matrix, each block relating to a subset of modes of said optical fiber; (c) a step of determining a gain and / or a transmission capacity (130) for each of the subsets of modes associated with said blocks; (d) a step of selecting (140) the subset of modes corresponding to the gain and / or the highest capacity (e), the MIMO transmission system then using only the modes of the subset thus selected to transmit on said optical fiber.
    [0002]
    Mode selection method according to claim 1, characterized in that the transformation of the transfer matrix comprises a thresholding step in which all elements of the matrix lower than a predetermined threshold value are set to zero, followed by a reorganization step of the transfer matrix thus obtained, by permutation of its rows and columns, the permutations on the rows and those on the columns being identical.
    [0003]
    Mode selection method according to claim 1 or 2, characterized in that the subset of modes is selected according to the gain criterion nopt = argmax (rn) where yn = Tr (HnHH), where N is the number of subsets of n = 1,, N modes, where Hn is the transfer matrix of the reduced transmission channel to the modes of subset n, HH being the conjugated transposed matrix of Hn and Tr (.) being the trace function .
    [0004]
    A method of selecting modes according to claim 1 or 2, characterized in that the subset of modes is selected according to the criterion of (name gain = arg max where yn Tr (11nHnH), where N is the number of subsets of n = 1,, N modes, Mn being the cardinality of the subset n, Hn being the transfer matrix of the reduced transmission channel to the modes of the subset n, HH being the conjugated transposed matrix of Hn and Tr (.) Being the trace function.
    [0005]
    Mode selection method according to claim 1 or 2, characterized in that the subset of modes is selected according to a capacity criterion nopt = arg max (Cn) where Cn = log 1+ n = 1, .. , N m = 1 M nN 0) Pe, where Mn is the cardinality of the subset n, y11 'being the gain of the transmission channel on the mode m of the subset n, Pe being the transmission power distributed over the Mn modes and No being the noise power at the reception on a mode.
    [0006]
    A method of selecting modes according to claim 1 or 2, characterized in that the subset of modes is selected according to a hybrid gain and capacity criterion nopt = argmax (413 (Cn, rn)) where Cn is the capacity of the reduced transmission channel n = 1,, N to the modes of the subset n, rn = Tr (HnHnH) where Hn is the transfer matrix of the reduced transmission channel to the modes of the subset n, HH being the conjugated transpose matrix of Hn and Tr (.) being the trace function, and where 1 (.,.) is an increasing function of Cn and yn. 25 3025676 18
    [0007]
    7. Mode selection method according to one of the preceding claims, characterized in that following the selection of the subset of modes, the degree of modulation of the symbols to be transmitted on the different modes is chosen equal to a value Q ' such that M log Q '= M log Q where M is the cardinal of all the modes before selection, M' is the cardinal of the subset of modes selected and Q is the degree of modulation of the symbols to be transmitted before selection of the subset of modes.
    [0008]
    8. mode selection method according to one of claims 1 to 6, characterized in that, following the selection of the subset of modes, the degree of modulation of the symbols to be transmitted on the different modes is chosen different for the different modes of the subset of modes.
    [0009]
    9. mode selection method according to one of the preceding claims, characterized in that the symbols to be transmitted are subjected to a spatio-temporal coding, the elements of the space-time code being then transmitted only on the modes of said subsystem. set of modes selected.
    [0010]
    A method of selecting cores for a multi-core optical fiber MIMO transmission system comprising: (a) a step of measuring (210) the transfer matrix of the transmission channel consisting of a set of cores of said optical fiber ; (b) transforming (220) said transfer operation into a block diagonal matrix, each block relating to a subset of cores of said optical fiber; (C) a step of determining a gain and / or transmission capacity (230) for each of the subsets of cores associated with said blocks; (d) a step of selecting (240) the subset of cores corresponding to the gain and / or the highest capacity (e), the MIMO transmission system then using only the cores of the subset thus selected to transmit on said optical fiber. 3025676 19
    [0011]
    A method of selecting cores according to claim 10, characterized in that the transformation of the transfer matrix comprises a thresholding step in which all elements of the matrix smaller than a predetermined threshold value are set to zero, followed by a reorganization step of the transfer matrix thus obtained, by permutation of its rows and columns, the permutations on the rows and those on the columns being identical.
    [0012]
    A method of selecting cores according to claim 10 or 11, characterized in that the subset of cores is selected according to the gain criterion nopt = argmax (rn) where yn = Tr (HnlinH), where N is the number of subsets of n = 1,, N cores, Hn being the transfer matrix of the reduced transmission channel at the core of the subset n, HH being the conjugated transposed matrix of Hn and Tr (.) being the trace function. 15
    [0013]
    A method of selecting cores according to claim 10 or 11, characterized in that the subset of cores is selected according to the criterion of (where yn = Tr (finite), where N is the number of nopt gain subsets. = arg max n = 1, .., N Mn / hearts, Mn being the cardinal of the subset n, Hn being the transfer matrix of the reduced transmission channel at the hearts of the subset n, HH being the transposed matrix conjugate of Hn and Tr (.) being the trace function.
    [0014]
    Mode selection method according to claim 10 or 11, characterized in that the subset of cores is selected according to a firing capacity criterion (25 nopt = argmax (Cn) where Cn = log 1 + e, Mn being the cardinal of the subset n = 1, .., N m = 1 M nN 0 / n, where y is the gain of the transmission channel on the core m of the subset n, P, being the power of d distributed emission on the Mn hearts and No being the power of noise on reception on a heart.
    [0015]
    15. A method of selecting cores according to claim 10 or 11, characterized in that the subset of cores is selected according to a hybrid gain and capacity criterion n0 = argmax (413 (Cn, yn)) where Cn is the capacity of the reduced transmission channel n = 1,, N at the subset of the subset n, yn = Tr (finite) where Hn is the transfer matrix of the reduced transmission channel at the subset of the subset n, H being the conjugated transpose matrix of Hn and Tr (.) being the trace function, and where 1 (.,.) is an increasing function of Cn and yn.
    [0016]
    16. A method of selecting cores according to one of claims 10 to 15, characterized in that following the selection of the subset of cores, the modulation degree of the symbols to be transmitted on the different cores is chosen equal to a value Q 'such that MlogQ' = M log Q where M is the cardinal of all the cores before selection, M 'is the cardinal of the selected subset of cores and Q is the degree of modulation of the symbols to be transmitted before the selection. selection of the subset of hearts.
    [0017]
    17. A method of selecting cores according to one of claims 10 to 15, characterized in that following the selection of the subset of cores, the degree of modulation of the symbols to be transmitted on the different cores is chosen different for the different hearts of the subset.
    [0018]
    18. A method of selecting cores according to one of claims 10 to 17, characterized in that the symbols to be transmitted are subjected to spatio-temporal coding, the elements of the space-time code being then transmitted only on the cores of said subset of modes selected.
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    同族专利:
    公开号 | 公开日
    WO2016037930A1|2016-03-17|
    CN107078804A|2017-08-18|
    EP3192192B1|2018-06-13|
    CN107078804B|2019-11-19|
    KR101989709B1|2019-09-30|
    KR20170115477A|2017-10-17|
    US20170264367A1|2017-09-14|
    EP3192192A1|2017-07-19|
    US10122461B2|2018-11-06|
    FR3025676B1|2016-12-23|
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    优先权:
    申请号 | 申请日 | 专利标题
    FR1458379A|FR3025676B1|2014-09-08|2014-09-08|METHOD OF SELECTING MODES / HEARTS FOR TRANSMISSION ON OPTICAL FIBERS OF THE MULTI-MODE / MULTI-HEART TYPE|FR1458379A| FR3025676B1|2014-09-08|2014-09-08|METHOD OF SELECTING MODES / HEARTS FOR TRANSMISSION ON OPTICAL FIBERS OF THE MULTI-MODE / MULTI-HEART TYPE|
    US15/508,775| US10122461B2|2014-09-08|2015-09-04|Method for selecting modes for transmission over multimode or multicore optical fibres|
    PCT/EP2015/070202| WO2016037930A1|2014-09-08|2015-09-04|Method for selecting modes for transmission over multimode or multicore optical fibres|
    EP15763253.0A| EP3192192B1|2014-09-08|2015-09-04|Method for selecting modes for transmission over multimode or multicore optical fibres|
    KR1020177006258A| KR101989709B1|2014-09-08|2015-09-04|Method for selecting modes for transmission over multimode or multicore optical fibres|
    CN201580047888.7A| CN107078804B|2014-09-08|2015-09-04|Method for selecting the mode for transmitting in multimode or multi-core optical fiber|
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