| 摘要 |
An apparatus and a method of compensating for an I/Q imbalance in a direct up-conversion system prevents the performance of the system from being deteriorated by efficiently compensating for an I/Q timing skew, an I/Q phase imbalance, and an I/Q gain imbalance by using a characteristic of an OFDM scheme in an Orthogonal Frequency Domain Multiple (Access) (OFDM(A)) system using a direct up-conversion scheme. According to the apparatus and the method of compensating for an I/Q imbalance in the direct up-conversion system of the present invention, an OFDM(A) system using a direct up-conversion scheme may efficiently compensate for I/Q timing skew, I/Q phase imbalance, and I/Q gain imbalance by using a characteristic of an OFDMA scheme, so that a performance of the system is prevented from being deteriorated. |
| 主权项 |
1. An In-phase/Quadrature-phase (I/Q) imbalance compensation apparatus in a direct up-conversion system, the I/Q imbalance compensation apparatus comprising:
a pre-distortion factor calculator for fetching pre-measured I/Q imbalance factors and calculating pre-distortion factors A, B, C, and D; and a pre-distortion executer for executing a pre-distortion for each subcarrier through the distortion factors A, B, C, and D corresponding to each subcarrier, wherein the pre-distortion factors A, B, C, and D are calculated by following equations,Phasetiming_shew=2*π*(subcarrierindex-(N2-1))*Δf*τN2≤subcarrierindex<NpointFFTA=0.5*[(1+g)*cos(φ)+(1-g)*cos(φ)*cos(Phasetime_skew)-(1+g)*sin(φ)*sin(Phasetime_skew)]B=0.5*[(g-1)*sin(φ)+(1-g)*cos(φ)*sin(Phasetime_skew)+(1+g)*sin(φ)*cos(Phasetime_skew)]C=0.5*[(1+g)*cos(φ)-(1-g)*cos(φ)*cos(Phasetime_skew)-(1+g)*sin(φ)*sin(Phasetime_skew)]D=0.5*[(g-1)*sin(φ)+(1-g)*cos(φ)*sin(Phasetime_skew)-(1+g)*sin(φ)*cos(Phasetime_skew)], in which τ indicates I/Q timing skew, g indicates an I/Q gain imbalance, Φ indicates an I/Q phase imbalance, Δf indicates sampling rate/FFT size, and N indicates an FFT size. |
