Abstract
Multiple-input, multiple-output (MIMO) communications have attracted considerable attention in the last years. In particular, multiuser MIMO (MU MIMO) systems are able to offer higher link capacity of MIMO systems as long as channel state information (CSI) is available at the transmitter, so that the spatial properties of the channel can be exploited by precoding. However, the time varying nature of the channel may cause CSI to be outdated, thus degrading the overall performance of the system. Within this context, channel prediction can provide up-to-date channel CSI and reduce the performance loss. This paper presents a channel predictor based on the setmembership partial update affine projection (SM-PUAP) filtering as way to compensate the outdated CSI caused by the temporal variations of the communication channel in a multiuser MIMO OFDM (orthogonal frequency division multiplexing) system. A realistic standardized channel model is considered to evaluate the predictor and its influence on the broadcast channel of a multiuser MIMO scenario. The performance of the predictor is also compared to the well-known adaptive algorithm recursive least squares (RLS). Simulation results show that the SM-PUAP predictor has lower computational cost and superior performance when compared to the classical algorithm.
Highlights
O RTHOGONAL frequency division multiplexing (OFDM) and systems with multiple antennas, or multiple-input, multiple-output (MIMO), are considered essential techniques for the generation cellular systems, referred to as 4G, considering the fact that high data rates and spectral efficiency are expected even for high mobility users [1]
It is presented a multiuser MIMO OFDM channel prediction scheme based on the concept of setmembership partial update affine projection filtering (SMPUAP) as a way to compensate the outdated channel state information (CSI) caused by the temporal variations of the communication channel
An adaptive channel predictor based on the set-membership partial update affine projection algorithm was presented for multiuser MIMO OFDM communications over time-varying channels
Summary
O RTHOGONAL frequency division multiplexing (OFDM) and systems with multiple antennas, or multiple-input, multiple-output (MIMO), are considered essential techniques for the generation cellular systems, referred to as 4G (fourth generation), considering the fact that high data rates and spectral efficiency are expected even for high mobility users [1]. Due to system constraints, such as the time-varying nature of the mobile wireless channel, scheduling algorithms and feedback delay, the CSI may be outdated, and this mismatch can severely degrade the data rate and the performance of the system In this manner, the channel response needs to be predicted far ahead for reliable transmission and to explore full capabilities offered by multiuser MIMO systems [12]. The effect of channel prediction on precoding techniques has been not yet considered in the literature Based on this exposition, the main contribution of this work is to propose the application of the SM-PUAP algorithm as an adaptive MIMO channel predictor.
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