A Two-Priority Frame-Synchronization Algorithm.

Most digital communication involves the transmission of data in distinct and identifiable groups of bits, sometimes referred to as frames. In many types of systems, separate control channels for marking frame boundaries are unavailable and frame-synchronization information must be embedded in the data stream. The standard techniques for synchronization are inadequate in situations in which both of the following are true 1 data can be transmitted only occasionally and in amounts not necessarily corresponding to frames 2 data frames are divided into two categories, high priority and low priority, with high priority indicating time-critical information. In these situations the transmitter data queue should operate as a priority queue i.e., it should operate in a first-in-first-out fashion except that when high-priority bits enter the queue they immediately move past any low-priority bits already in the queue. Because this can result in a high-priority frame being inserted into the middle of a partially transmitted low-priority frame, the synchronization algorithm in this context needs to do two things in a compatible way 1 delimit low-priority frames and 2 mark high-priority frames in such a way that they can be detected anywhere in the low-priority data stream. This report describes such an algorithm. Author