Helsinki University of Technology

About: Helsinki University of Technology is a based out in . It is known for research contribution in the topics: Thin film & Vortex. The organization has 8962 authors who have published 20136 publications receiving 723787 citations. The organization is also known as: TKK & Teknillinen korkeakoulu.

Advanced methods for I/Q imbalance compensation in communication receivers

Abstract: I/Q signal processing is widely utilized in today's communication receivers However, all I/Q processing receiver structures, such as the low-IF receiver, face a common problem of matching the amplitudes and phases of the I and Q branches In practice, imbalances are unavoidable in the analog front-end, which results in finite and usually insufficient rejection of the image frequency band This causes the image signal to appear as interference on top of the desired signal We carry out general signal analysis of an imbalanced I/Q processing receiver and propose novel methods for I/Q imbalance compensation using baseband digital signal processing A simple structure for compensation is derived, based on a traditional adaptive interference canceller Improved image rejection can also be obtained by using more advanced blind source separation techniques Theoretical analysis of the performance of the proposed imbalance compensation structures is presented In addition, some simulation results are provided in order to further evaluate the performance of the proposed methods The results indicate that the I/Q imbalance can be effectively compensated during the normal operation of the receiver even in the rapidly changing case, as long as a linear system model for the imbalance is valid

On Unscented Kalman Filtering for State Estimation of Continuous-Time Nonlinear Systems

Abstract: This paper considers the application of the unscented Kalman filter (UKF) to continuous-time filtering problems, where both the state and measurement processes are modeled as stochastic differential equations. The mean and covariance differential equations which result in the continuous-time limit of the UKF are derived. The continuous-discrete UKF is derived as a special case of the continuous-time filter, when the continuous-time prediction equations are combined with the update step of the discrete-time UKF. The filter equations are also transformed into sigma-point differential equations, which can be interpreted as matrix square root versions of the filter equations.