Question

Consider a (48, 36) block error correcting code used in the downlink control channel of a cellular system. This code can correct up to 5 bit errors in a block of 48 bits.

If the 48 bit blocks are buffered until 10 blocks are collected and then they are interleaved and transmitted, what is the maximum error burst size that can be tolerated and still have correct reception of the data?

What is the delay incurred in buffering the data for interleaving and de-­interleaving at a 48 kbps rate?

Answer 1

First Question:

The Burst error detection theorem states that the maximum burst error that can be detected is n - k.

According to the question n = 48 and k = 36

So, the maximum detectable burst error = (48 - 36) = 12

The theorem of burst error correction states that the maximum number of burst errors that can be corrected for any (n, k) block of code is l <= n - k - log_q(n - l) + 2

We have n = 48, k = 36 and l = 5.

For the given scenario l <= 48 - 36 - log(48 - 5) + 2

or, l<= 14 - 5.2

or, l <= 8.7

So, the possible value is 8.

Hope this helps.