Multi-carrier modulation and demodulation method based on orthogonal non-uniform multi-carrier spacing based on Ramanujan sum
A multi-carrier modulation and demodulation method technology, applied in the field of multi-carrier modulation and demodulation, can solve the problems of increasing inter-carrier interference, frequency fading, loss of inter-carrier orthogonality, etc., achieve low complexity and reduce inter-carrier interference Effect
Active Publication Date: 2017-02-15
BEIHANG UNIV
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Problems solved by technology
[0004] For high-speed mobile communication systems, modulation transmission technology faces two main problems: 1) frequency selective fading caused by large path delay spread; 2) time selective fading caused by Doppler effect (mainly Doppler spread)
Although the carrier spacing can be modulated, the calculation is complicated, and the orthogonality between carriers is lost, which increases the impact of inter-carrier interference.
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[0047] The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings. The present invention determines the carrier spacing according to the channel response, so as to avoid the frequency band with excessive noise in the channel. as attached figure 1 , the light color is the channel noise distribution, and the dark color is the normalized carrier spectrum.
[0048] Step 1: The transmitting end determines the non-uniformly spaced carrier according to the current channel state, and the selected carrier position can be determined by searching the Ramanujan sum frequency point distribution table, and then determine the modulation base.
[0049] Specifically include:
[0050](1.1) Normalize the channel amplitude response and frequency, and remove the frequency bands whose amplitude response is lower than the set threshold after normalization.
[0051] (1.2) Determine the selected modulation base according to the...
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The invention discloses a multi-carrier modulation and demodulation method of orthogonal non-uniform multi-carrier spacing based on Ramanujan summation. The method comprises the following steps that step 1, a sending terminal determines non-uniform spacing carriers according to the current channel state, determines positions of the carriers through searching a frequency point distribution table of the Ramanujan summation, and then determining modulation bases; step 2, carrying out inverse Ramanujan Fourier transformation and data modulation by adopting the modulation bases obtained in the step 1; and step 3, a receiving terminal carries out demodulation by using Ramanujan Fourier transformation. The multi-carrier modulation and demodulation method disclosed by the invention carries out carrier spacing allocation according to channel state information, the orthogonality of carriers is kept, and interferences among the carriers are reduced. The modulation bases can realize differential protection for different carriers, and can also carry out difference mapping at the sending terminal to acquire equal data protection. The multi-carrier modulation and demodulation method is low in implementation complexity, and can a lower transmission bit error rate than that of uniformly distributed carriers in a non-uniform channel.
Description
technical field [0001] The invention relates to a multi-carrier modulation and demodulation method based on Ramanujan sum and orthogonal non-uniform multi-carrier spacing, belonging to the technical field of communication. Background technique [0002] As a parallel data processing method, multi-carrier modulation technology can effectively resist multipath fading and improve the data transmission rate of wireless band-limited channels. As the mainstream modulation method of multi-carrier modulation, the traditional Orthogonal Frequency Division Multiplexing (OFDM) technology uses uniformly spaced sub-carriers for modulation. This equidistant division does not take into account the different degrees of channel attenuation for different carriers. When the attenuation of a certain channel is large, the increase of the bit error rate of the sub-channel will affect the transmission performance of the whole system. [0003] The main idea of non-uniform spacing multi-carrier m...
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IPC IPC(8): H04L27/26
Inventor 王祖林周丽娜黄勤
Owner BEIHANG UNIV