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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 inability to correct unbalanced parameters in real time, difficult implementation, high algorithm complexity, etc. , to achieve significant compensation effect, less damage, and simple hardware implementation

Inactive Publication Date: 2003-01-22
SHANGHAI JIAO TONG UNIV
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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

[0029] This embodiment adopts a hybrid structure based on Field Programmable Logic Array (FPGA) and Digital Signal Processor (DSP), as attached image 3 shown. Quadrature Modulation Compensation Unit (QMCU) is implemented in FPGA as a separate functional module, including input switching part, compensation calculation part and interface part; the realization of compensation control unit (QMCC) is mainly based on the system structure of DSP, which provides and includes The interface of the network detector A / D conversion unit and the interface with FPGA.

[0030] The forward branch works as follows: After the OFDM baseband signal IQ is processed by the shaping filter (PSF), it is sent to the quadrature modulation compensation unit (QMCU) for pre-compensation, and the obtained data enters the AQM device for analog normalization after D / A conversion. Intermodulation, modulation to the passband, completes a transmission process.

[0031] Feedback branch consists of envelope dete...

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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 (OFDM) is a multi-carrier digital modulation technique in which a transmitted signal is superimposed by a group of mutually orthogonal sinusoidal signals as subcarrier modulation. OFDM technology has good anti-fading ability and channel bandwidth utilization rate. [0003] In the OFDM communication system, I and Q signals are modulated onto the passband spectrum by analog quadrature modulation (AQM). Due to the limited performance of physical devices, modulation errors are caused, which mainly manifests in three aspects: gain and phase Imbalance (IQ Channel Gain / Phase Imbalance), DC Offset (DCOffset). The imbalance of AQM causes adjacent channel power ACP ...

Claims

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Application Information

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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 JIAO TONG UNIV
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