1,764 research outputs found
Analysis of cyclic delay diversity on DVB-H systems over spatially correlated channel
The objective of this work is to research and analyze the performance of Cyclic Delay Diversity (CDD) with two transmit antenna on DVB-H systems operating in spatially correlated channel. It is shown in this paper that CDD can achieve desirable transmit diversity gain over uncorrelated channel with or without receiver diversity. However, in reality, the respective signal paths between spatially separated antennas and the mobile receiver is likely to be correlated because of insufficient antenna separation at the transmitter and the lack of scattering effect of the channel. Under this spatially correlated channel, it is apparent that CDD cannot achieve the same diversity gain as obtained under the uncorrelated channel. In this paper, a new upper bound on the pairwise error probability (PEP) of the CDD with spatial correlation of two transmit antennas is derived. The upper bound is used to study the CDD theoretical error performance and diversity gain losses over a generalized spatially correlated Rayleigh channel. This theoretical analysis is validated by the simulation of DVB-H systems with two transmit antennas and the CDD scheme. Both the theoretical and simulated results give the valuable insight that the CDD ability to perform well with a certain amount of channel correlation
On Outage Probability and Diversity-Multiplexing Tradeoff in MIMO Relay Channels
Fading MIMO relay channels are studied analytically, when the source and
destination are equipped with multiple antennas and the relays have a single
one. Compact closed-form expressions are obtained for the outage probability
under i.i.d. and correlated Rayleigh-fading links. Low-outage approximations
are derived, which reveal a number of insights, including the impact of
correlation, of the number of antennas, of relay noise and of relaying
protocol. The effect of correlation is shown to be negligible, unless the
channel becomes almost fully correlated. The SNR loss of relay fading channels
compared to the AWGN channel is quantified. The SNR-asymptotic
diversity-multiplexing tradeoff (DMT) is obtained for a broad class of fading
distributions, including, as special cases, Rayleigh, Rice, Nakagami, Weibull,
which may be non-identical, spatially correlated and/or non-zero mean. The DMT
is shown to depend not on a particular fading distribution, but rather on its
polynomial behavior near zero, and is the same for the simple
"amplify-and-forward" protocol and more complicated "decode-and-forward" one
with capacity achieving codes, i.e. the full processing capability at the relay
does not help to improve the DMT. There is however a significant difference
between the SNR-asymptotic DMT and the finite-SNR outage performance: while the
former is not improved by using an extra antenna on either side, the latter can
be significantly improved and, in particular, an extra antenna can be
traded-off for a full processing capability at the relay. The results are
extended to the multi-relay channels with selection relaying and typical outage
events are identified.Comment: accepted by IEEE Trans. on Comm., 201
Impact of Spatial Correlation on the Finite-SNR Diversity-Multiplexing Tradeoff
The impact of spatial correlation on the performance limits of multielement
antenna (MEA) channels is analyzed in terms of the diversity-multiplexing
tradeoff (DMT) at finite signal-to-noise ratio (SNR) values. A lower bound on
the outage probability is first derived. Using this bound accurate finite-SNR
estimate of the DMT is then derived. This estimate allows to gain insight on
the impact of spatial correlation on the DMT at finite SNR. As expected, the
DMT is severely degraded as the spatial correlation increases. Moreover, using
asymptotic analysis, we show that our framework encompasses well-known results
concerning the asymptotic behavior of the DMT.Comment: Accepted for publication to IEEE Transaction on Wireless
Communication on June 4th 200
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