Information AboutInterleaving |
| CATEGORIES ABOUT INTERLEAVING | |
| error detection and correction | |
|
It is used in: By Interleaving one denotes the process of many linearily countable objects being put in an, at first sight, unordered order. Interleaving is mainly used in data communication, Multimedia File Format s, Radio Transmission (for example in Satellite s) or by ADSL . Historically, interleaving has also been used in ordering Block Storage on Hard Disk s. The term Multiplexing is sometimes used to refer to the interleaving of Digital Signal data. INTERLEAVING IN DATA TRANSMISSION Today, interleaving is mainly used in digital data transmission technology, to protect the transmission against Burst Errors . These errors have the characteristics that they overwrite a lot of bits in a row, but occur very seldomly. Interleaving is used to solve this problem. All data is transmitted (independently from the interleaving) with some control bits that enable the channel decoder to correct a certain number of tampered bits. If a burst error occures, more than this number of bits are tampered and the codeword cannot be correctly decoded. So the bits of a number of codewords are interleaved and then transmitted. That way, a burst error affects only a correctable number of bits in each codeword, so the decoder can decode the codewords correctly. Let's take a look at an example. We apply to an error correcting code so that the channel codeword has four bits and one-bit-errors can be corrected. The channel codewords are put into a block like this: aaaabbbbccccddddeeeeffffgggg. Consider transmission without interleaving: Error-free transmission: aaaabbbbccccddddeeeeffffgggg transmission with a burst error: aaaabbbbccc____deeeeffffgggg The codeword dddd is tampered in three bits, so it cannot be decoded (decoding failure) or might be decoded into a wrong codeword (false decoding). Which of the two happens, depends on the error correcting code applied. Now, lets do the same with interleaving: Error-free transmission: abcdefgabcdefgabcdefgabcdefg transmission with a burst error: abcdefgabcd____bcdefgabcdefg De-interleaved transmission with one burst error: aa_abbbbccccdddde_eef_ffg_gg Of each of the codewords aaaa, eeee, ffff, gggg only one bit is tampered, so our one-bit-error-correcting-code can decode everything correctly. Of course, latency is added by this, because we cannot send the second bit of codeword a before awaiting the first bit of codeword gggg. Look at graphical Representation of interleaving Advantages of interleaving
Disadvantages of interleaving
|
|
|