Title :
Modified delay-locked loop for fading channels
Author_Institution :
Inst. of Commun. Technol., German Aerosp. Res. Establ., Wessling, Germany
Abstract :
The delay-locked loop (DLL) is well suited to guarantee fine synchronization for direct-sequence spread spectrum systems. In fading channels the mean time to lose lock (MTLL) of a DLL is very important because a loss of loci during a fade makes a re-acquisition process necessary. Using a two state model for the fading channel and a modified DLL will improve the MTLL considerably. The modified DLL operates in two different modes: a normal tracking mode for good channel conditions, and a “fade” mode for bad channel conditions, i.e. during a deep fade. The modified DLL is more robust against bad channel conditions
Keywords :
delay circuits; digital radio; fading; pseudonoise codes; spread spectrum communication; synchronisation; telecommunication channels; bad channel conditions; channel conditions; deep fade; direct-sequence spread spectrum system; fading channels; fine synchronization; mean time to lose lock; modified delay-locked loop; re-acquisition process; tracking mode; two state model; Clocks; Delay; Fading; Jitter; Phase estimation; Signal to noise ratio; Spread spectrum communication; Timing; Tracking loops; Voltage-controlled oscillators;
Conference_Titel :
Signals, Systems, and Electronics, 1995. ISSSE '95, Proceedings., 1995 URSI International Symposium on
Conference_Location :
San Francisco
Print_ISBN :
0-7803-2516-8
DOI :
10.1109/ISSSE.1995.497968
