The performance of a high-mobility PACS radio link with time delay spread

Abstract

The PACS radio interface is the leading low-tier candidate for standardization in North America. This radio interface was originally conceived to serve pedestrian and fixed-distribution applications; there has been significant interest in extending this technology into high-mobility environments. Our previous work studied PACS at vehicular speeds; this paper continues the work to include the effects of time delay spread. It is found that RSSI with a short measurement length can better cope with high fading rates than can the quality measure in a preselection diversity system, although the quality measure has a better performance than received signal strength indicator (RSSI) at low speeds in the presence of time delay spread. The performance of preselection diversity degrades rapidly for RMS delay spreads larger than about 9% of a symbol time. Postselection diversity using two complete receiver chains is more robust than preselection diversity both to high fading rates and to delay spread. The performance of postselection diversity is relatively insensitive to changes in the fading rate and can tolerate an RMS delay spread of up to 12.5% of a symbol time.