1,700 research outputs found
Capacity Results for Block-Stationary Gaussian Fading Channels with a Peak Power Constraint
We consider a peak-power-limited single-antenna block-stationary Gaussian
fading channel where neither the transmitter nor the receiver knows the channel
state information, but both know the channel statistics. This model subsumes
most previously studied Gaussian fading models. We first compute the asymptotic
channel capacity in the high SNR regime and show that the behavior of channel
capacity depends critically on the channel model. For the special case where
the fading process is symbol-by-symbol stationary, we also reveal a fundamental
interplay between the codeword length, communication rate, and decoding error
probability. Specifically, we show that the codeword length must scale with SNR
in order to guarantee that the communication rate can grow logarithmically with
SNR with bounded decoding error probability, and we find a necessary condition
for the growth rate of the codeword length. We also derive an expression for
the capacity per unit energy. Furthermore, we show that the capacity per unit
energy is achievable using temporal ON-OFF signaling with optimally allocated
ON symbols, where the optimal ON-symbol allocation scheme may depend on the
peak power constraint.Comment: Submitted to the IEEE Transactions on Information Theor
The Noncoherent Rician Fading Channel -- Part I : Structure of the Capacity-Achieving Input
Transmission of information over a discrete-time memoryless Rician fading
channel is considered where neither the receiver nor the transmitter knows the
fading coefficients. First the structure of the capacity-achieving input
signals is investigated when the input is constrained to have limited
peakedness by imposing either a fourth moment or a peak constraint. When the
input is subject to second and fourth moment limitations, it is shown that the
capacity-achieving input amplitude distribution is discrete with a finite
number of mass points in the low-power regime. A similar discrete structure for
the optimal amplitude is proven over the entire SNR range when there is only a
peak power constraint. The Rician fading with phase-noise channel model, where
there is phase uncertainty in the specular component, is analyzed. For this
model it is shown that, with only an average power constraint, the
capacity-achieving input amplitude is discrete with a finite number of levels.
For the classical average power limited Rician fading channel, it is proven
that the optimal input amplitude distribution has bounded support.Comment: To appear in the IEEE Transactions on Wireless Communication
Low SNR Capacity of Noncoherent Fading Channels
Discrete-time Rayleigh fading single-input single-output (SISO) and
multiple-input multiple-output (MIMO) channels are considered, with no channel
state information at the transmitter or the receiver. The fading is assumed to
be stationary and correlated in time, but independent from antenna to antenna.
Peak-power and average-power constraints are imposed on the transmit antennas.
For MIMO channels, these constraints are either imposed on the sum over
antennas, or on each individual antenna. For SISO channels and MIMO channels
with sum power constraints, the asymptotic capacity as the peak signal-to-noise
ratio tends to zero is identified; for MIMO channels with individual power
constraints, this asymptotic capacity is obtained for a class of channels
called transmit separable channels. The results for MIMO channels with
individual power constraints are carried over to SISO channels with delay
spread (i.e. frequency selective fading).Comment: submitted to IEEE I
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