Transmitting and receiving apparatus and method in an orthogonal frequency division multiplexing system
A technology of orthogonal frequency division and receiving equipment, applied in the field of preprocessing equipment, which can solve problems such as high noise, poor system performance, and Q filter complexity
Inactive Publication Date: 2005-02-09
SAMSUNG ELECTRONICS CO LTD +1
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Problems solved by technology
[0011] figure 1 One of the disadvantages of the FEQ-DMT receiver shown is the complexity of the Q filter
Another disadvantage is that noise within the signal on the redundant carrier is added to the signal on the data carrier within the Q filter, resulting in increased noise
Because redundant carriers usually have poor SNR, the noise on the redundant carrier spreads to the data carrier, resulting in poorer system performance
Method used
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[0028] Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. In the following description, well-known functions or constructions will not be described in detail since they would obscure the invention in detail.
[0029] As noted above, the present invention will prevent system performance degradation caused by ICI and ISI involved in multiple carriers.
[0030] Figure 2A The structure of an OFDM data frame with a CP longer than the CIR is illustrated. Such as Figure 2A As shown, the nth frame is X n 1:N , the length of CP is L cp . Here, N is both the length of the transmission frame and the number of all carriers. Last L of N samples cp Sampled replicas are added before the nth frame as a cyclic CP. The length of the CIR is L. If L cp Equal to or greater than L, the CP prevents ICI and ISI because a CP longer than the CIR is between these frames.
[0031] Figure 2B The structure of an OFDM frame wit...
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A preprocessing apparatus and method for a transmitter and a receiver to prevent system performance degradation caused by Inter-Channel Interference (ICI) or inter-symbol interference (ISI) in an OFDM system. In the OFDM system using N carriers having different frequency bands and K carriers of the N carriers designated as redundant carriers, the transmitter renders ICI-causing parts to be zeroes in a data frame, when a cyclic prefix is not longer than a channel impulse response. Therefore, the ICI is prevented. The receiver eliminates the ISI involved in a current frame using an interference estimated from a previous data frame. Therefore, noise spread caused by the use of redundant carriers is prevented and system complexity is remarkably reduced.
Description
technical field [0001] The present invention relates generally to OFDM (Orthogonal Frequency Division Multiplexing) systems, and in particular, to preprocessing devices and methods in transmitter / receivers for preventing system performance from being affected by ICI (Inter-Channel Interference) or ISI (Inter-Symbol interference) caused by the reduction. Background technique [0002] OFDM is a multi-carrier modulation scheme that splits data on multiple carriers and transmits the split data in parallel at a low rate, thereby reducing frequency selective fading or narrowband interference, and transmitting at a high rate The conventional single-carrier scheme for data is different. In OFDM, the spectrum of the subcarriers overlaps each other orthogonally, which improves the spectral efficiency. The transmitted signal is modulated by FFT (Inverse Fast Fourier Transform), and the received signal is demodulated by FFT (Fast Fourier Transform). Thus, digital modulators and demod...
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IPC IPC(8): H04J11/00H04L25/03H04L27/26
CPCH04L5/0007H04L5/006H04L5/0046H04L2025/03414H04J11/00
Inventor 李钟赫金映秀任基弘元熙喆朴喆进
Owner SAMSUNG ELECTRONICS CO LTD