Bit stuffing

In <a href="/facts/Data_transmission/1yAhaANd">data transmission</a> and <a href="/facts/Telecommunications/vxoj1cxR">telecommunications</a>, bit stuffing (also known—uncommonly—as positive justification) is the insertion of non-information <a href="/facts/Binary_digit/S972NSaD">bits</a> into <a href="/facts/Data/AUBFN97o">data</a>. Stuffed bits should not be confused with <a href="/facts/Overhead_bit/xuskA0wY">overhead bits</a>.
Bit stuffing is used for various purposes, such as for bringing <a href="/facts/Bit_stream/Pf9oGYyY">bit streams</a> that do not necessarily have the same or rationally related <a href="/facts/Bit_rate/ppUNMmVd">bit rates</a> up to a common rate, or to fill <a href="/facts/Buffer_(telecommunication)/tVy4j2Dc">buffers</a> or <a href="/facts/Data_frame/ltGCbJIq">frames</a>. The location of the stuffing bits is communicated to the receiving end of the <a href="/facts/Data_link/fSNk5Nus">data link</a>, where these extra bits are removed to return the bit streams to their original bit rates or form. Bit stuffing may be used to synchronize several channels before <a href="/facts/Multiplexing/YE7hK8cw">multiplexing</a> or to rate-match two single channels to each other.
Another use of bit stuffing is for <a href="/facts/Run_length_limited/WkGWpAGR">run length limited</a> coding: to limit the number of consecutive bits of the same value in the data to be transmitted. A bit of the opposite value is inserted after the maximum allowed number of consecutive bits. Since this is a general rule the receiver doesn't need extra information about the location of the stuffing bits in order to do the de-stuffing. This is done to create additional signal transitions to ensure reliable reception or to escape special reserved code words such as frame <a href="/facts/Sync_sequence/rU9xSwJV">sync sequences</a> when the data happens to contain them.

Bit stuffing does not ensure that the payload is intact (i.e. not corrupted by transmission errors); it is merely a way of attempting to ensure that the transmission starts and ends at the correct places. <a href="/facts/Error_detection_and_correction/o2rH8e3n">Error detection and correction</a> techniques are used to check the frame for corruption after its delivery and, if necessary, the frame will be re-sent.

Bit stuffing open-in-new

Bit stuffing