1. A method of decoding a code block, comprising: concatenating, at a receiver, a first code block that is at least a part of a data stream from a first user, and a second code block that is at least a part of a data stream from a second user, to form a concatenated code block, at least one set of guard bits being inserted between the first and second code blocks, the concatenated code block including at least one string of zeros between the guard bits and at least one of the first and second code blocks, and the number of guard bits in the at least one set of guard bits being based on a size of the concatenated code block; and decoding, at the receiver, the concatenated code block in a single decode operation.