Citation
Abstract
The current DSN frame synchronization procedure is based on monitoring the decoded bit stream for the appearance of a sync marker sequence that is transmitted once every data frame. This article explores the possibility of obtaining frame synchronization by processing the raw received channel symbols rather than the decoded bits. Performance results are derived for three channel symbol sync methods, and these are compared with results for decoded bit sync methods reported elsewhere. It is shown that each class of methods has advantages or disadvantages under different assumptions on the frame length, the global acquisition strategy, and the desired measure of acquisition timeliness. It is shown that the sync statistics based on decoded bits are superior to the statistics based on channel symbols, if the desired operating region utilizes a probability of miss many orders of magnitude higher than the probability of false alarm. This operating point is applicable for very large frame lengths and minimal frameto-frame verification strategy. On the other hand, the statistics based on channel symbols are superior if the desired operating point has a miss probability only a few orders of magnitude greater than the false alarm probability. This happens for small frames or when frame-to-frame verifications are required. Among the three channel symbol methods examined, the squared-distance statistic offers the best performance in the range of normal signal-to-noise ratios, but it degrades more rapidly than the correlation statistic or the hard-limited symbol discrepancy count statistic when the signal-to-noise ratio is extremely low.
Details
- Volume
- 42-98
- Published
- August 15, 1989
- Pages
- 121–137
- File Size
- 705.2 KB