A real-time wireless control system is required to provide an information exchange between a controller and a large number of slaves within a limited cycle time, e.g. 1 ms. To shorten preamble transmission time, we have proposed uplink preamble-less transmission [1] and subcarrier-selected short preambles (SSSP) [2] for wireless control systems. Since the preambles are shortened, the packet errors are more likely to occur and consequently the system needs more retransmissions. This leads to a trade-off between shortened preamble transmission time and iterated retransmissions. In this paper, we perform MAC/PHY cross-layer evaluation of total transmission time including the retransmission delay in a wireless control system. Comparing with traditional full-length preambles, the result shows that the shortened preambles yield less transmission time.
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