A decoder unit is configured to perform a decoding on encoded data. The decoder unit includes a data bus comprising a number N of data lines, a local memory configured to store messages for a message-passing decoding and communicate the messages across the data bus, a plurality of first decoder processing units, wherein each first decoder processing unit is configured to perform the message-passing decoding by communicating with the local memory using a number A of the data channels, and a plurality of second decoder processing units, where each second decoder processing unit is configured to perform the message-passing decoding by communicating with the local memory using a number B of the data lines. N is at least two, A and B are less than or equal to N, and A is different from B.