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A time change channel estimating method for OFDM system

A technology of time-varying channel and channel, which is applied in the field of channel estimation of OFDM system, and can solve problems such as noise

Inactive Publication Date: 2008-04-23
UNIV OF ELECTRONIC SCI & TECH OF CHINA
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Problems solved by technology

However, in an actual channel, only a few of the L taps are channel taps (that is, the discrete impulse response, denoted as L'), and the taps other than the L' channel taps are noise
Therefore, due to the influence of noise, the above channel estimation algorithm has a certain estimation error, especially in the case of low received SNR

Method used

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  • A time change channel estimating method for OFDM system
  • A time change channel estimating method for OFDM system
  • A time change channel estimating method for OFDM system

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Embodiment Construction

[0084] The implementation method of this patent under a specific OFDM configuration is given below. It should be noted that the parameters in the following examples do not affect the generality of this patent.

[0085] This implementation method adopts the simulation tool matlab, and the useful symbol length of OFDM is N=512; the system simulation parameters are shown in Figure 6 , for the channel model parameters used see Figure 7

[0086] 1. Origin:

[0087] 20 OFDM symbols constitute a frame (that is, M=20), the number of pilot carriers in the first symbol is 256, 4 pilot carriers form a cluster, and each cluster is evenly spaced by 4 carriers. The number of pilot carriers of the remaining symbols is 64, and 4 pilot carriers form a cluster, and each cluster is evenly spaced by 32 carriers. After IFFT transformation, a cyclic prefix with a length of 144 is added to each OFDM original symbol and transmitted.

[0088] Second, the receiving end

[0089] Perform channel e...

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Abstract

When normalized Doppler shift is less than 0.2, the method uses characteristic of linear variation of time varying channel to carry out iterative noise cancellation for taps needed to estimate in order to restrain influence on channel estimation from noise so as to obtain tap coefficient of channel as well as transition matrix of channel. The receiving end carries out iterative channel estimation for first symbol of each frame and removing noise influence so as to obtain locations of channel taps. Subsequent symbol estimates tap coefficients of channel for assured locations without need of iteration. The method can remove influence on time varying channel estimation caused by noise, raises accuracy for estimating channel and spectrum utilization ratio. Moreover, the invention possesses features of low complexity of integral calculation.

Description

technical field [0001] The invention belongs to the field of wireless communication, and particularly relates to a channel estimation method of an OFDM system. Background technique [0002] Orthogonal Frequency Division Multiplexing (OFDM: Orthogonal Frequency Division Multiplexing) technology has been paid more and more attention due to its advantages of high data transmission rate, strong anti-multipath interference capability, and high spectrum efficiency. It has been successfully used for wired and wireless communications. Such as: DAB (Digital Audio Broadcasting), DVB, IEEE802.11a and HyperLAN / 2. OFDM, a new modulation technology, can also be used in a new generation of mobile communication systems. OFDM technology will greatly improve the transmission data rate and spectrum efficiency of the new generation mobile communication system, and has a good anti-multipath ability, see the literature: Bingham, J.A.C., "Multicarrier modulation for data transmission: an idea wh...

Claims

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Application Information

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IPC IPC(8): H04L27/26H04J11/00H04L12/26H04B17/00
Inventor 雷霞李筝李少谦
Owner UNIV OF ELECTRONIC SCI & TECH OF CHINA
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