Recent Advances in Acquiring Channel State Information in Cellular MIMO Systems

Abstract

In cellular multiuser multiple input multiple output (MU-MIMO) systems the quality of the available channel state information (CSI) has a large impact on the system performance. Specifically, reliable CSI at the transmitter is required to determine the appropriate modulation and coding scheme, transmit power and the precoder vector, while CSI at the receiver is needed to decode the received data symbols. Therefore, cellular MU-MIMO systems employ predefined pilot sequences and configure associated time, frequency, code and power resources to facilitate the acquisition of high quality CSI for data transmission and reception. Although the trade-off between the resources used for pilot and user data transmission has been known for long, the near-optimal configuration of the available system resources for pilot and data transmission is a topic of current research efforts. Indeed, since the fifth generation of cellular systems utilizes heterogeneous networks in which base stations are equipped with a large number of transmit and receive antennas, the appropriate configuration of pilot-data resources becomes a critical design aspect. In this article, we review recent advances in system design approaches that are designed for the acquisition of CSI and discuss some of the recent results that help to dimension the pilot and data resources specifically in cellular MU-MIMO systems. Index Terms-Multi-antenna systems, channel state information, estimation techniques, receiver algorithms.

Detection of 2x2 MIMO signals

“…As a result, the standing constellation diagrams appear soon at the output, and remain almost constant for the rest of the measurement interval. Other Hungarian efforts concerning MIMO technique are found in [11]. A possible use of MIMO is presented in [12].…”