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Analog orthogonal modulation unbalance compensating method

A technology of orthogonal modulation and compensation method, which is applied in the direction of orthogonal multiplexing system, transmission control/equalization, multi-carrier system, etc., and can solve problems such as difficult implementation, high algorithm complexity, and inability to correct unbalanced parameters in real time , to achieve the effect of small damage, simple hardware implementation, and significant compensation effect

Inactive Publication Date: 2004-06-02
SHANGHAI JIAOTONG UNIV
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  • Abstract
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Problems solved by technology

Among the various existing digital compensation algorithms, typical examples are M.Faulkner, T.Mattsson and W.Yates. In Automatic adjustment of quadrature modulators. (Electronics Letters, vol.27, no.3, pages 214-216, January 1991.) The compensation algorithm proposed in the paper adopts the algorithm based on the test tone, which has the disadvantage of not being able to correct the unbalanced parameters in real time. Another example is D.S.Hilborn, S.P.Stapleton and J.K.Cavers. In An Adaptive direct conversion transmitter.IEEE Transaction on Vehicular Technology , vol.43, no.2, pp 223-233, the algorithm based on adjacent channel power surface fitting proposed in May 1994 has too high algorithm complexity and is difficult to implement

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  • Analog orthogonal modulation unbalance compensating method
  • Analog orthogonal modulation unbalance compensating method
  • Analog orthogonal modulation unbalance compensating method

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Embodiment

[0032] This embodiment adopts a hybrid structure based on a field programmable logic array (FPGA) and a digital signal processor (DSP), as attached image 3 Shown. The quadrature modulation compensation unit (QMCU) is implemented as a separate functional module in FPGA, including the input switching part, the compensation calculation part and the interface part; the realization of the compensation control unit (QMCC) is mainly based on the DSP-based system structure, providing and packaging The interface of the network detector A / D conversion unit and the interface with FPGA.

[0033] The forward branch works as follows: After the two OFDM baseband signals IQ are processed by the shaping filter (PSF), they are sent to the quadrature modulation compensation unit (QMCU) for pre-compensation, and the data obtained is converted into the AQM device for analog positive after D / A conversion. Intermodulation, modulation to the passband, completes a transmission process.

[0034]The feedbac...

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Abstract

This invention relates to an analog compensation method for quadrature modulation of unbalance using the following steps: substep unbalance compensation based on testing phoneme in the switch-on stage and unbalance compensation based on analog Newton iteration in the receiving and sending process, a compensation control unit uses envelope detector to detect the analog quadrature-modulated signal for its peak envelope to get IQ two routes DC bias compensation coefficient, phase unbalance compensation coefficient, and gain unbalance coefficient. The base-band signals to be delivered in first sent to QMCU for pretreatment, then to analog quadrature modulator modulated on the pass-band to make output signals reach or be approximate to the performance of ideal quadrature modulators.

Description

Technical field: [0001] The invention relates to an analog quadrature modulation imbalance compensation method, which is used in an orthogonal frequency division multiplexing communication system and belongs to the technical field of communication. Background technique: [0002] Orthogonal Frequency Division Multiplexing (Orthogonal Frequency Division Multiplexing, OFDM) is a multi-carrier digital modulation technology in which a set of mutually orthogonal sinusoidal signals are modulated and superimposed as sub-carriers. OFDM technology has good anti-fading ability and channel bandwidth utilization. [0003] In the OFDM communication system, the I and Q signals are modulated to the passband spectrum by analog quadrature modulation (AQM). Due to the limited performance of physical devices, modulation errors are caused, which are mainly manifested in three aspects: gain and phase. Imbalance (IQ Channel Gain / Phase Imbalance), DC offset (DCOffset). The imbalance of AQM causes the si...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04B7/005H04J11/00H04L27/32
Inventor 陈柏南周跃峰胡亮亮宋文涛罗汉文
Owner SHANGHAI JIAOTONG UNIV