MIMO-FBMC transmitter/receiver with linear precoding implemented in the frequency domain

• US 9,948,373 B2
• Filed: 05/11/2017
• Issued: 04/17/2018
• Est. Priority Date: 05/13/2016
• Status: Active Grant

• Current Assignee: Commissariat a L'Energie Atomique (French Alternative Energies and Atomic Energy Commission)
• Original Assignee: Commissariat a L'Energie Atomique (French Alternative Energies and Atomic Energy Commission)
• Inventors: Cassiau, Nicolas
• Primary Examiner(s): Malek, Leila
• Application Number:
  US15/592,535
• Publication Number:
  US 20170331536A1
• Time in Patent Office: 341 Days
• Field of Search: 375260, 375259, 375295
• CPC Class Codes: H04B 7/0456 Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
• CPC Class Codes: H04B 7/046 taking physical layer constraints into account
• CPC Class Codes: H04L 27/26416 Filtering per subcarrier, e.g. filterbank multicarrier [FBMC]
• CPC Class Codes: H04L 27/2654 Filtering per subcarrier, e.g. filterbank multicarrier [FBMC]
• CPC Class Codes: H04L 27/2698 double density OFDM/OQAM system, e.g. OFDM/OQAM-IOTA system

Abstract

The invention relates to a MIMO-FBMC transmitter/receiver with linear precoding implemented in the frequency domain. In one embodiment, at the transmitter the linear precoding is performed (525₁, . . . ,525_KN) after filtering and spectral spreading, before the IFFT and combination of FBMC symbols in the time domain, such that the precoding does not introduce interference between data streams. In a second embodiment the linear precoding may be combined with the beamforming at transmission or at reception so as to spatially separate the data streams.

Claims

1. A Multiple Input Multiple Output Filter Bank Multi-Carrier (MIMO-FBMC) transmitter for transmitting a plurality U of data streams on a transmission channel using a plurality N^T of transmission antennas characterised in that it comprises:

a plurality U of Offset Quadrature Amplitude Modulation (OQAM) modulators associated with the U data streams, each modulator receiving a stream data vector and supplying a vector of N alternating real and imaginary components for N sub-channels, where N is equal to an integer greater than 1

a plurality U of filtering and spectral spreading modules associated with the U modulators, each filtering and spectral spreading module spreading each component over 2K−

1 adjacent sub-carriers and filtering them using a prototype filter transfer function, where K is the overlap factor equal to an integer greater than 1, in order to supply KN spread and filtered components that represent KN subcarriers;

a plurality KN of linear precoders, associated respectively with the KN sub-carriers, each linear precoder multiplying the spread and filtered components relating to a sub-carrier (j) by a precoding matrix (P_j) in order to supply a plurality KN of precoded vectors;

a plurality (N^T) of inverse Fast Fourier Transform (IFFT) modules each receiving elements with the same index as the precoded vectors, where each IFFT module supplies a time signal which represents an FBMC symbol;

a plurality (N^T) of FBMC symbol combination modules in the time domain, associated respectively with the IFFT modules in order to supply combined time signals;

a plurality (N^T) of modules for translation of frequency to radio frequency (RF) band to generate, from said combined time signals, a plurality N^T of antenna signals destined to be transmitted by said transmission antennas.

2. The MIMO-FBMC transmitter according to claim 1 characterised in that a number of said plurality of IFFT modules, a number of said plurality of FBMC symbol combination modules and a number of said plurality of translation to RF band modules are all equal to the number N^T of transmission antennas, the antenna signals being generated by translation to the RF band of said combined time signals.

3. The MIMO-FBMC transmitter according to claim 2, characterised in that the precoding matrices are of size N^T ×

U.

4. The MIMO-FBMC transmitter according to claim 3, characterised in that, the number U of data streams is chosen to be equal to the number N^T of transmission antennas, and that the precoding matrices associated with the various sub-carriers are respectively equal to the inverse of the matrix of the transmission channel at the frequencies of said sub-carriers.

5. The MIMO-FBMC transmitter according to claim 1, characterised in that a number of said plurality of IFFT modules, a number of said plurality of FBMC symbol combination modules and a number of said plurality of RF band translation modules are all equal to a number N^B of beams, said combined time signals translated to RF band by said modules for translation to RF band each being multiplied by a phase-shift vector, with the antenna signals being generated by summing the components of the vectors thus obtained.

6. The MIMO-FBMC transmitter according to claim 5, characterised in that the precoding matrices are of size N^B ×

U.

7. The MIMO-FBMC transmitter according to claim 6, characterised in that the number N^B of beams is chosen to be equal to the number U of data streams, and the precoding matrices associated with the various sub-carriers are respectively equal to the inverse of the product of a matrix (W_RF) resulting from concatenation of the phase-shift vectors, with the matrix of the transmission channel for the various sub-carriers.

8. A Multiple Input Multiple Output Filter Bank Multi-Carrier (MIMO-FBMC) receiver for receiving a plurality U of data streams on a transmission channel using a plurality N^R of reception antennas characterised in that it comprises:

a plurality (N^R) of Fast Fourier transform (FFT) modules of size KN where N is the number of FBMC sub-channels equal to an integer greater than 1 and K is the overlap factor equal to an integer greater than 1, for transforming blocks of KN samples of reception signals generated from antenna signals and translated to a base band, into vectors of KN frequency components;

a plurality KN of linear precoders, respectively associated with KN sub-carriers, each linear precoder multiplying a vector of frequency components at the sub-carrier which is associated with it by a precoding matrix (V_j) to supply a plurality KN of precoded vectors of size U;

a plurality U of filtering and frequency despreading modules, where each module filters and despreads the frequency components of the precoded vectors associated with a sub-carrier to provide a plurality U of filtered and despread component vectors;

a plurality U of Offset Quadrature Amplitude Modulation (OQAM) demodulation modules in order to demodulate, respectively, the U filtered and despread component vectors and to provide U estimated data flows.

9. The MIMO-FBMC receiver according to claim 8, characterised in that a number of said plurality of FFT modules is equal to the number N^R of reception antennas, where the reception signals are equal to the antenna signals.

10. The MIMO-FBMC receiver according to claim 9, characterised in that the number U is chosen to be equal to the number N^R of reception antennas, and that the precoding matrices (V_j) associated with the various sub-carriers are respectively equal to the inverse of the matrix of the transmission channel at the frequencies of said sub-carriers.

11. The MIMO-FBMC receiver according to claim 8, characterised in that a number of said plurality of FFT modules is equal to a predetermined number N^B of beams, the reception signals being obtained by multiplying all of the antenna signals by N^B phase-shift vectors of size N^B to obtain N^B vectors of phase-shift signals, the components of each vector of phase-shift signals then being summed to provide a reception signal.

12. The MIMO-FBMC receiver according to claim 11, characterised in that the precoding matrices are of size N^B ×

U.

13. The MIMO-FBMC receiver according to claim 12, characterised in that the number N^B of beams is chosen to be equal to the number U of data streams, and that the precoding matrices associated with the various sub-carriers are respectively equal to the inverse of the product of a matrix (W_RF) resulting from concatenation of the phase-shift vectors, with the matrix of the transmission channel for the various sub-carriers.