12,557 research outputs found
Distortion Exponent in MIMO Channels with Feedback
The transmission of a Gaussian source over a block-fading multiple antenna
channel in the presence of a feedback link is considered. The feedback link is
assumed to be an error and delay free link of capacity 1 bit per channel use.
Under the short-term power constraint, the optimal exponential behavior of the
end-to-end average distortion is characterized for all source-channel bandwidth
ratios. It is shown that the optimal transmission strategy is successive
refinement source coding followed by progressive transmission over the channel,
in which the channel block is allocated dynamically among the layers based on
the channel state using the feedback link as an instantaneous automatic repeat
request (ARQ) signal.Comment: Presented at the IEEE Information Theory Workshop (ITW), Taormina,
Italy, Oct. 200
Joint source-channel coding with feedback
This paper quantifies the fundamental limits of variable-length transmission
of a general (possibly analog) source over a memoryless channel with noiseless
feedback, under a distortion constraint. We consider excess distortion, average
distortion and guaranteed distortion (-semifaithful codes). In contrast to
the asymptotic fundamental limit, a general conclusion is that allowing
variable-length codes and feedback leads to a sizable improvement in the
fundamental delay-distortion tradeoff. In addition, we investigate the minimum
energy required to reproduce source samples with a given fidelity after
transmission over a memoryless Gaussian channel, and we show that the required
minimum energy is reduced with feedback and an average (rather than maximal)
power constraint.Comment: To appear in IEEE Transactions on Information Theor
An Adaptive Source-Channel Coding with Feedback for Progressive Transmission of Medical Images
A novel adaptive source-channel coding with feedback for
progressive transmission of medical images is proposed here. In
the source coding part, the transmission starts from the region of
interest (RoI). The parity length in the channel code varies with
respect to both the proximity of the image subblock to the RoI and
the channel noise, which is iteratively estimated in the receiver.
The overall transmitted data can be controlled by the user
(clinician). In the case of medical data transmission, it is vital
to keep the distortion level under control as in most of the cases
certain clinically important regions have to be transmitted
without any visible error. The proposed system significantly
reduces the transmission time and error. Moreover, the system is
very user friendly since the selection of the RoI, its size,
overall code rate, and a number of test features such as noise
level can be set by the users in both ends. A MATLAB-based TCP/IP
connection has been established to demonstrate the proposed
interactive and adaptive progressive transmission system. The
proposed system is simulated for both binary symmetric channel
(BSC) and Rayleigh channel. The experimental results verify the
effectiveness of the design
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