A method for estimating in-phase/quadrature unbalance in ofdm system and its module

A technology for balancing and estimating values, applied in transmission systems, multi-carrier systems, multi-frequency code systems, etc., can solve problems such as IQ imbalance, high complexity, and high implementation complexity, and achieve low timing requirements, simple algorithms, and high application wide-ranging effect

CN106911607BInactive Publication Date: 2019-11-15SHANGHAI RES CENT FOR WIRELESS COMM
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Publication Date
2019-11-15
Estimated Expiration
Not applicable · inactive patent

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Abstract

The invention discloses an estimation method and module for in-phase / quadrature-phase (IQ) imbalance in an OFDM (Orthogonal Frequency Division Multiplexing) system. The estimation method comprises the following steps: S1, performing frequency offset compensation on received time domain signals; S2, after removing cyclic prefixes, transforming two different pilot symbols adjacent on time to a frequency domain; S3, extracting subcarriers occupied by the pilot symbols according to the system bandwidth; S4, for the two pilot symbols, obtaining received signals of two pilot signals on each subcarrier; and S5, removing coupling of IQ imbalance parameters and channels, and solving an IQ imbalance estimation value. The method and the module are wide in application and low in requirement for the processing time sequence of a receiver, conform to the demands of most practical application scenes, and are simple in algorithm and small in calculation quantity.
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Description

technical field

[0001] The invention relates to a method and module for estimating in-phase / quadrature-phase (In-phase / Quadrature-phase, referred to as IQ) imbalance in an OFDM (orthogonal frequency division multiplexing) system, which belongs to wireless communication technology field. Background technique

[0002] In common OFDM communication systems (such as 802.11a / g / n / ac series and LTE, etc.), in order to improve spectrum utilization efficiency, high-order modulation or MIMO technology is generally used. These complex transmission schemes require the receiver to be able to achieve a relatively high signal-to-noise ratio (SNR). However, the transceiver is limited by the production cost and may need to use relatively low-priced devices. Its non-ideal IQ imbalance characteristics will lead to a decrease in the signal-to-noise ratio at the receiving end and seriously affect the receiving performance. In order to improve the receiving performance, it is necessary to accura...

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Embodiment Construction

[0036] The technical content of the present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0037] The present invention assumes that there are two different pilots adjacent in time in the OFDM system, and the channel of the two pilot signals on the same subcarrier is flat. This assumption is generally established in common OFDM communication systems. For example, (1) STF / LTF in the 802.11a / g / n / ac system is separated by 8us in time, which is used in the LAN environment and has a high time correlation; (2) two columns of DMRS signals on the PUSCH in the LTE system, Contains different cyclic shifts, with a time interval of 0.5ms. When used in common scenarios with a speed of less than 120km / h, the time correlation is relatively high.

[0038] The following takes the IQ imbalance estimation process in the 802.11a / g / n / ac system as an example to illustrate the method for estimating the in-phase / quadrature imbala...