Impact of runlengths of dropped packets in shared time division duplexing (STDD)

There has been interest in the area of short distance wireless access to the ubiquitous telephone network. These systems are often referred to in the context of personal communication networks (PCNs) or personal communication systems (PCSs). STDD (shared time division duplexing) is a high capacity, high quality, low delay multiple access technique for microcellular systems. By sharing time slots in both directions of transmission, it provides a considerable increase in capacity over the conventional time division systems with slow speech activity detection (SAD). We investigate the temporal robustness of STDD. We consider the statistics of the runlength of dropped packets and show that both STDD and TDMA/TDD/SAD may suffer from long periods of dropped packets at full capacity. We introduce circular interleaving as a method of reducing the runlength of dropped packets, at a cost of a negligible increase in control information. A number of numerical results are included for the short frame length of 2 ms.