Abstract
In recent years, distributed unique word (DUW) has been widely used in satellite single carrier TDMA signals, such as very small aperture terminal (VSAT) satellite systems. Different from the centralized structure of traditional unique word, DUW is uniformly dispersed in a burst signal, where the traditional unique word detection methods are not applicable anymore. For this, we propose a robust burst detection algorithm based on DUW. Firstly, we allocated the sliding detection windows with the same structures as DUW in order to effectively detect it. Secondly, we adopt the method of time delay conjugate multiplication to eliminate the influence of frequency offset on detection performance. Due to the uniform dispersion of DUW, it naturally has two different kinds of time delays, namely the delay within the group and the delay between the two groups. So, we divide the traditional dual correlation formula into two parts to calculate them separately and obtain a dual correlation detection algorithm, which is suitable for DUW. Simulation and experimental results demonstrate that when the distribution structure of DUW changes, detection probability of the proposed algorithm fluctuates little, and its variance is 1.56×10−5, which is 99.83% lower than the existing DUW detection algorithms. In addition, its signal to noise ratio (SNR) threshold is about 1 dB lower than the existing algorithms under the same circumstance of the missed detection probability.
Highlights
We propose a burst detection algorithm for distributed unique word (DUW) Time division multiple access (TDMA) signals in satellite communications
We analyze the principle of traditional dual correlation (TDC) and the influence of DUW structure on the delay conjugate multiplication
We combine DUW with TDC and obtain a dual correlation detection algorithm, which is suitable for DUW
Summary
There are mainly the following burst detection algorithms for TDMA signal. The energy based detection algorithm [6,7,8] can determine the existence of burst signal by detecting the energy within the window This kind of method has good anti-frequency offset performance; it is sensitive to noise and is not suitable for detection under low SNR conditions. Current signal detection algorithms based on UW mainly consider the distribution of UW in signal frame head [14,15,16,17], and we have not seen much research on DUW, except Hou and Hou algorithms [18] They have advantages of good antifrequency offset, but do not behave well at lower SNR and are greatly influenced by the structure of UW. In order to improve detection accuracy and robustness, burst detection based on DUW needs further research
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