Channel State Information Estimation In MIMO-OFDM Wireless Systems

Abstract

Multiple Input Multiple Output (MIMO) in combination with Orthogonal Frequency Division Multiplexing (OFDM) can provide spectrally efficient and ISI free communication. Channel estimation is of great importance in order to recover the signal at the receiver side. Therefore accurate channel state information is essential for proper detection and decoding in MIMO-OFDM wireless systems. To estimate channel state information various types of techniques are being deployed in these systems. Accuracy and precision of channel estimation depends on the techniques used for the purpose of estimating channel state information. The more the accuracy of the technique, more will be the accurate performance of the system. In this paper we provide a review of the various types of techniques that are used in estimation of channel in MIMO-OFDM systems. Although the existing CE techniques for OFDM can be employed for MIMO-OFDM systems too but the computation complexity is increased in the latter. The techniques can be chosen on the basis of their performance which can be judged by Mean Square Error (MSE), convergence speed, and the stability of the algorithm. Various CE techniques like LS and MMSE can be used. Moreover adaptive CE techniques like LMS, NLMS, RLS are gaining more attention. These can be chosen based on the system requirement and the environment in which the system is to be deployed. Comparison of the techniques on the basis of above given parameters is shown in this paper. Also the improvement aspects for techniques of channel estimation are discussed.