Coding and Interleaving

Consider a TDMA system that transmits information in frames of 8 bits. The probability that a frame is subject to fading is $P_f=0.1$. If a frame is subject to fading the probability that a bit is in error is $P_{e\vert f}=0.5$. Otherwise if there is no fading the bit error probability is $P_{e\vert n}=0$.

1. What is the probability that a frame is received that does not contain any errors?
2. Assume now that the information has been coded such that one bit error per frame can be corrected. No interleaving is employed. Compute the probability that a decoded frame does not contain any bit errors.
3. Assume now that bits are interleaved over 8 frames such that each deinterleaved frame contains exactly one bit from each of the transmitted, interleaved frames. What is the probability of a bit error if no coding is used?
4. Compute the probability that a frame does not contain any errors if both coding and interleaving are employed.