A deletion channel is a communications channel model used in coding theory and information theory.
In this model, a transmitter sends a bit (a zero or a one), and the receiver either receives the bit (with probability
) or does not receive anything without being notified that the bit was dropped (with probability
Determining the capacity of the deletion channel is an open problem.
[1][2] The deletion channel should not be confused with the binary erasure channel which is much simpler to analyze.
The iid binary deletion channel is defined as follows: Given an input sequence of
The deletion positions are unknown to the sender and the receiver.
which were not deleted, in the correct order and with no errors.
The capacity of the binary deletion channel (as an analytical expression of the deletion rate
It has a mathematical expression[citation needed].