Consider the downlink of an isolated cell with a base station (BS) equipped with M multiple antennas and a single user with a single antenna. For this multiple-input single-output (MISO) channel, the capacity with perfect channel state information (CSI) the transmitter and receiver is known. In practice, however, it is actually more realistic to assume imperfect CSI at the transmitter. For inst...

Abstract—Adaptive modulation has been shown to have significant benefits for high-speed wireless data transmission when orthogonal frequency division multiplexing (OFDM) is employed. However, accurate channel state information (CSI) is required at the transmitter to achieve the benefits. Imperfect CSI arises from noisy channel estimates, which may also be outdated due to a delay in getting the ...

Multiple-input multiple-output (MIMO) antenna systems provide high capacity gain over a single-antenna system. This gain is maximised when channel state information (CSI) is available at the transmitter. In practice, however, only partial information could be obtained. In this paper, we shall present a study of the MIMO system capacity in the case of imperfect CSI. It is found that in the case ...

Abstract — For a space-time coded system in a correlated Rayleigh fading environment, we consider two receiver structures: (1) a suboptimum one in which the imperfect channel state information (CSI) is used in place of perfect CSI in a perfect CSI optimum receiver, (2) the optimum receiver in which the imperfect CSI is used in the maximum likelihood sense. Channel estimation is done by the use ...

Employing multiple transmit and receive antennas for wireless transmissions opens up the opportunity to meet the demand of high-quality high-rate services envisioned for future wireless systems with minimum possible resources, e.g., spectrum, power and hardware. Empowered by linear precoding and decoding, a spatially multiplexed multiple-input multiple-output (MIMO) system becomes a convenient ...

Channel estimation via training is a common method for providing imperfect channel state information (CSI) in a network. In a relay network, imperfect CSI can be efficiently provided at the relays by sending training signals from the source and the destination nodes to the relays. Providing imperfect CSI at the destination is more challenging since each relay is required to send training signal...

Adaptive resource allocation based on perfect Channel State Information (CSI) can significantly improve the performance of Orthogonal Frequency Division Multiple Access (OFDMA) systems. However, in real systems, accurate CSI is impossible because of noisy channel estimates, channel feedback delays, and processing delays. Therefore, only imperfect CSI can be used for resource allocation purposes...

We investigate the ergodic sum rate and required transmit power of a single-cell massive multiple-input multiple-output (MIMO) downlink system. The system considered in this paper is based on two linear beamforming schemes, that is, maximum ratio transmission (MRT) beamforming and zero-forcing (ZF) beamforming. What’s more, we use minimum mean square error (MMSE) channel estimation to get imper...

Most works on amplify and forward (AF) relaying assume that the relay obtains perfect channel state information (CSI) of the source-relay channel. This renders variable-gain relaying (VGR) an attractive technique, as the relay can ideally invert the channel at its input and thus ensure constant output power. What happens to the output power, however, if the CSI at the input is outdated? As an a...

Coordinated Multi-Point (CoMP) systems promise very high performance in terms of spectral efficiency and coverage benefits when perfect Channel State Information (CSI) is available at the transmitter. However, perfect CSI is difficult to obtain in CoMP systems due to an increased number of channel parameters to estimate at the receiver and to be fed back to the transmitter. So, the performance ...