Marco Chiani — Page 4

arXiv2007

Pragmatic Space-Time Trellis Codes for Block Fading Channels

A pragmatic approach for the construction of space-time codes over block fading channels is investigated. The approach consists in using common convolutional encoders and Viterbi decoders with suitable generators and rates, thus greatly simplifying the implementation of space-time codes. For the design of pragmatic space-time codes a methodology is proposed and applied, based on the extension of the concept of generalized transfer function for convolutional codes over block fading channels. Our search algorithm produces the convolutional encoder generators of pragmatic space-time codes for various number of states, number of antennas and fading rate. Finally it is shown that, for the investigated cases, the performance of pragmatic space-time codes is better than that of previously known space-time codes, confirming that they are a valuable choice in terms of both implementation complexity and performance.

cs.IT↗

arXiv2005

On the Capacity of Doubly Correlated MIMO Channels

In this paper, we analyze the capacity of multiple-input multiple-output (MIMO) Rayleigh-fading channels in the presence of spatial fading correlation at both the transmitter and the receiver, assuming that the channel is unknown at the transmitter and perfectly known at the receiver. We first derive the determinant representation for the exact characteristic function of the capacity, which is then used to determine the trace representations for the mean, variance, skewness, kurtosis, and other higher-order statistics (HOS). These results allow us to exactly evaluate two relevant information-theoretic capacity measures--ergodic capacity and outage capacity--and the HOS of the capacity for such a MIMO channel. The analytical framework presented in the paper is valid for arbitrary numbers of antennas and generalizes the previously known results for independent and identically distributed or one-sided correlated MIMO channels to the case when fading correlation exists on both sides. We verify our analytical results by comparing them with Monte Carlo simulations for a correlation model based on realistic channel measurements as well as a classical exponential correlation model.

cs.IT↗