In the design of an error correcting code, what can be the impact of such channel parameters.
Dear Abraham,
This is really a good question and it needs investigations to precisely answer it.
In order to answer it, i will stick to the basic principles and concepts of the channel performance and the channel coding.
Assume you have a communication channel that has multipath effects such that the delay spread of the symbols is Tau, The coherence bandwidth Bc = 1/ Tau. The consequence of this delay spread is the channel bandwidth is limited to certain bandwidth Bc which is termed the coherence bandwidth. It means that as the signal bandwidth is smaller than the channel coherence band width, the signal will suffer only from flat fading and the signal can be detected with correctly with very few errors. In case of that the bandwidth of the transmitted signal is greater than the coherent channel bandwidth the fading will be selective deep fading such that some signal frequencies will be severely attenuated. Such selective fading must be treated by frequency domain equalizers. Such that the channel response becomes flat at all signal frequencies.
Such frequency selective fading may be severe such that that one can not completely eliminate it by equalizers. Fast fading has also the same effect in case of
doppler spread which can be reduced by time domain equalizers. One can additionally utilize channel coding to reduce the bit error rate by detecting and correcting the errors in the bits.
There are two major types, the block codes and the convolutional codes. The convolutional codes are capable to correct discrete bit errors while Reed Solomon codes are capable to correct complete symbols and therefore are capable to combat burst errors. By adding interleaves to the the convolutional encoders they become capable to correct burst errors. To combat deep fading errors, a method capable to combat burst type error is required.
In summary ,It is so that one can use:
-RS encoders
- Interleavers + convolutional encoders,
- Turbo encoders which are composed of two recursive convolutionl encoders with inerleaver between the outer and the inner one.
It must be said the channel coding is basically used to enhance also, the white Guassian noise channels. and consequently all types of the channels.
Best wishes
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