Elements of information theory
Elements of information theory
Fundamentals of wireless communication
Fundamentals of wireless communication
Toeplitz And Circulant Matrices: A Review (Foundations and Trends(R) in Communications and Information Theory)
MIMO Wireless Communications
The capacity region of broadcast channels with intersymbol interference and colored Gaussian noise
IEEE Transactions on Information Theory
Duality, achievable rates, and sum-rate capacity of Gaussian MIMO broadcast channels
IEEE Transactions on Information Theory
Diversity–Multiplexing Tradeoff of Asynchronous Cooperative Diversity in Wireless Networks
IEEE Transactions on Information Theory
| Hi-index | 0.00 |
Consider a multiple input multiple output (MIMO) system with pulse amplitude modulation (PAM), where each transmit antenna is allowed to choose a different transmission delay. (We refer to this system as a MIMO system with asynchronous PAM.) Such MIMO systems have been studied before for increasing diversity and avoiding unintentional beam-forming. We quantify the capacity/outage capacity improvement due to asynchronism and the corresponding spectral leakage (if any) for MIMO point-to-point and MIMO broadcast channels. We show that under commonly used transmitter spectral mask constraints, the channel has unbounded degrees of freedom. Synchronous PAM exploits only a finite number of these degrees of freedom, and asynchronism helps to improve capacity. For most cases of interest, two distinct shifts attain most of the capacity improvement. These gains are robust to interference from adjacent carriers. Analysis of the spectrum of the asynchronous PAM suggests that optimal water-filling based schemes are useful for improving capacity only in directional links due to possible spectral leakage, while uniform power allocation leads to capacity improvement without any extra spectral leakage.