Method and Apparatus for OFDM Spectral Diversity Using Guard Bands
AssigneeST-Ericsson SA
InventorsMerouane Debbah, Romain Couillet
Life of this patent
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Abstract
An OFDM modulation process and means for transmitting multiple carriers through a communication channel having a bandwidth arranged ion chunks with further subcarriers being allocated to form at least one guard band, comprising automatically and periodically shifting said chunks to the left or to the side in order to overlap said guard band and increase spectral diversity.
Claims10
An OFDM modulation process for transmitting multiple carriers through a communication channel having a bandwidth W split in N subcarriers arranged in K chunks of M subcarriers each, with N−K×M subcarriers being allocated to form at least one guard band,
- said process comprising the step of automatically and periodically shifting said chunks to the left or to the right sides in order to overlap said guard band and increase spectral diversity in short-time transmissions.
OFDM modulation system for transmitting multiple carriers through a communication channel having a bandwidth W split in N subcarriers arranged in K chunks of M subcarriers each, with N−K×M subcarriers being allocated to form at least one guard band,
- said system comprising means for automatically and periodically shifting said chunks to the left or to the side in order to overlap said guard band and increase diversity.
Method of OFDM-Data-Communication wherein data symbols are transformed into a frequency domain by Fourier Transformation turning a frequency-selective channel into N flat fading parallel transmission channels using a cyclic prefix (CP) to suppress inter-symbol interference (ISI) wherein a received signal r is identified from a sent signal s by r≈HF−1s+n, wherein n is Additive White Gaussian Noise with variance σ2, and H is a circulant matrix which is diagonalized in the Fourier basis F, with diagonal elements the discrete Fourier transform of the first column [h0, . . . , hL−1, 0, . . . , 0] by multiplying r in with F with
- F
- ·
- r
- =
- diag
-
- (
- H
-
- (
- 0
- )
- ,
- …
-
- ,
- H
-
- (
- N
- -
- 1
- N
- )
- )
-
- s
- +
- n
- ,
- wherein H(.) is the discrete Fourier transformation (DFT) of the first column of H.
- H
-
- (
- m
- N
- )
- =
- ∑
- j
- =
- 0
- L
- -
- 1
-
- h
- j
-
-
- -
- 2
-
- π
-
-
-
-
-
- j
-
- m
- n
- .
- characterized by multiplying the samples of the cyclic prefix by z=ρeiα where ρ is constrained to equal 1 and multiplying the OFDM signal by diag (1, e−iα/N, . . . , e−iα(N−1)/N) after the inverse DFT (IDFT), leading to α-OFDM.
Dependencies are inferred from the claim text.