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OFDM system frequency offset synchronization method based on constant envelope modulation

A constant envelope, frequency offset synchronization technology, applied in the direction of synchronization devices, transmission systems, multi-frequency code systems, etc., can solve problems such as only considering, not considering the applicability of algorithms, and limited application of algorithms

Inactive Publication Date: 2014-07-16
CHONGQING UNIV
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Problems solved by technology

[0005] At present, there are two main problems in the frequency offset blind tracking algorithm for SISO- and MIMO-OFDM systems: ① The algorithm uses a constant modulus constellation diagram, while most modern communication systems use QAM modulation with a higher modulation order, etc., and often in Different constellation maps are used on different subcarriers, so the application of the algorithm is limited; ② only considers the case of full load of the system, that is, all subcarriers are used for data transmission, and does not consider the applicability of the algorithm when there is an empty carrier in the OFDM system. There is still a distance from the actual application

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  • OFDM system frequency offset synchronization method based on constant envelope modulation
  • OFDM system frequency offset synchronization method based on constant envelope modulation
  • OFDM system frequency offset synchronization method based on constant envelope modulation

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Embodiment Construction

[0017] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0018] figure 1 It is a block diagram of the OFDM system of the present invention. Due to the complexity of the OFDM system, it is very difficult to describe it completely, and the established model is also difficult to analyze. Therefore, in the modeling process, some conditions of the system can be simplified or ignored: ①Assume that the channel frequency response has been estimated by the training symbols and remains unchanged in a frame, that is, the quasi-static fading channel (Quasi-Static Fading Channel); ②In At the receiving end, there are usually symbol timing errors and carrier frequency offsets. Since OFDM symbols contain cyclic prefixes, the impact of symbol timing errors is much smaller than carrier frequency offset. Here, it is assumed that the symbol synchronization algorithm has eliminated the timing errors, and only the im...

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Abstract

The invention discloses an OFDM system frequency offset synchronization method based on constant envelope modulation, and belongs to the technical field of wireless communication. According to the OFDM system frequency offset synchronization method based on constant envelope modulation, a transmitter carries out constant envelope transformation on a signal processed through constellation diagram mapping again, so that data have the constant modulus characteristic before being processed through IFFT, and channels obey quasi-static fading; a receiver synchronizes frequency offset through the energy difference between a minimized receipt signal and a known channel frequency response. The OFDM system frequency offset synchronization method has the advantages of being applicable to frequency offset blind synchronization of an MIMO-OFDM system of any constellation diagram, and applicable to the situation that null carrier waves exist in the OFDM system.

Description

technical field [0001] The invention belongs to the technical field of wireless communication, and relates to an OFDM system frequency offset synchronization method based on constant envelope modulation. Background technique [0002] With the continuous increase of multimedia services, the future wireless communication system puts forward higher requirements for transmission rate, bit error rate and spectrum efficiency, etc., and the traditional single-carrier narrowband transmission technology can no longer meet the requirements. How to effectively improve spectrum utilization, data transmission rate and communication quality has become one of the current hot research topics. Orthogonal Frequency Division Multiplexing (OFDM) is an orthogonal multi-carrier modulation technology, which converts the wideband frequency selective fading channel into a series of narrowband flat fading channels by expanding the symbol period, so it has a strong Anti-multipath fading and pulse int...

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Application Information

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IPC IPC(8): H04L27/26H04L7/00
Inventor 许炜阳王雨晴李有均
Owner CHONGQING UNIV
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