Topic
Channel state information
About: Channel state information is a research topic. Over the lifetime, 24615 publications have been published within this topic receiving 400910 citations.
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27 Jul 2000
TL;DR: In this paper, a diversity technique for communication over fading channels in the presence of interference is proposed. But the technique is not suitable for all channels and it is not applicable to all channels.
Abstract: FUNDAMENTALS. Fading Channel Characterization and Modeling. Types of Communication. MATHEMATICAL TOOLS. Alternative Representations of Classical Functions. Useful Expressions for Evaluating Average Error Probability Performance. New Representations of Some PDF's and CDF's for Correlative Fading Applications. OPTIMUM RECEPTION AND PERFORMANCE EVALUATION. Optimum Receivers for Fading Channels. Performance of Single Channel Receivers. Performance of Multichannel Receivers. APPLICATION IN PRACTICAL COMMUNICATION SYSTEMS. Optimum Combining: A Diversity Technique for Communication Over Fading Channels in the Presence of Interference. Direct--Sequence Code--Division Multiple Access. FURTHER EXTENSIONS. Coded Communication Over Fading Channels. INDEX.
1,955 citations
TL;DR: This paper considers the problem of secret communication between two nodes, over a fading wireless medium, in the presence of a passive eavesdropper, and assumes that the transmitter and its helpers (amplifying relays) have more antennas than the eavesdroppers.
Abstract: The broadcast nature of the wireless medium makes the communication over this medium vulnerable to eavesdropping. This paper considers the problem of secret communication between two nodes, over a fading wireless medium, in the presence of a passive eavesdropper. The assumption used is that the transmitter and its helpers (amplifying relays) have more antennas than the eavesdropper. The transmitter ensures secrecy of communication by utilizing some of the available power to produce 'artificial noise', such that only the eavesdropper's channel is degraded. Two scenarios are considered, one where the transmitter has multiple transmit antennas, and the other where amplifying relays simulate the effect of multiple antennas. The channel state information (CSI) is assumed to be publicly known, and hence, the secrecy of communication is independent of the secrecy of CSI.
1,846 citations
TL;DR: By judicious choice of the decoding radius, it is shown that this maximum-likelihood decoding algorithm can be practically used to decode lattice codes of dimension up to 32 in a fading environment.
Abstract: We present a maximum-likelihood decoding algorithm for an arbitrary lattice code when used over an independent fading channel with perfect channel state information at the receiver. The decoder is based on a bounded distance search among the lattice points falling inside a sphere centered at the received point. By judicious choice of the decoding radius we show that this decoder can be practically used to decode lattice codes of dimension up to 32 in a fading environment.
1,760 citations
TL;DR: A key finding is that the feedback rate per mobile must be increased linearly with the signal-to-noise ratio (SNR) (in decibels) in order to achieve the full multiplexing gain.
Abstract: Multiple transmit antennas in a downlink channel can provide tremendous capacity (i.e., multiplexing) gains, even when receivers have only single antennas. However, receiver and transmitter channel state information is generally required. In this correspondence, a system where each receiver has perfect channel knowledge, but the transmitter only receives quantized information regarding the channel instantiation is analyzed. The well-known zero-forcing transmission technique is considered, and simple expressions for the throughput degradation due to finite-rate feedback are derived. A key finding is that the feedback rate per mobile must be increased linearly with the signal-to-noise ratio (SNR) (in decibels) in order to achieve the full multiplexing gain. This is in sharp contrast to point-to-point multiple-input multiple-output (MIMO) systems, in which it is not necessary to increase the feedback rate as a function of the SNR
1,717 citations
25 Jul 1995
TL;DR: The authors present the MMSE and LS estimators and a method for modifications compromising between complexity and performance and the symbol error rate for a 18-QAM system is presented by means of simulation results.
Abstract: The use of multi-amplitude signaling schemes in wireless OFDM systems requires the tracking of the fading radio channel. The paper addresses channel estimation based on time-domain channel statistics. Using a general model for a slowly fading channel, the authors present the MMSE and LS estimators and a method for modifications compromising between complexity and performance. The symbol error rate for a 18-QAM system is presented by means of simulation results. Depending upon estimator complexity, up to 4 dB in SNR can be gained over the LS estimator.
1,647 citations