Delay-reliability tradeoffs in wireless networked control systems

摘要: Networked control systems (NCS) require the data to be communicated timely and reliably. However, random transmission errors incurred by wireless channels make it difficult achieve these qualities simultaneously. Therefore, a tradeoff between reliability latency exists in NCSs with channels. Previous work on usually assumed fixed delay, which implied that failed packet will discarded without retransmission, thus is reduced. When channel are severe, NCS cannot afford resulting loss. In this paper, delay-bounded (DB) packet-dropping strategy associated automatic repeat request (ARQ) at link layer such packets retransmitted unless they out-of-date. On one hand, delay controlled below predetermined bound. other improved because given more retransmission opportunities. This paper investigates loss rate DB strategies. Due multihop topology of NCS, medium access (MAC) schemes needed schedule multiple nodes. Moreover, spatial reuse should taken into account improve network throughput. two MAC considered, m-phase time division (TDMA) slotted ALOHA. They compared for different sampling rates bounds. TDMA outperforms ALOHA terms both end-to-end (e2e) when reception probability above 0.5 and/or traffic heavy. shows self-regulating ability node effective transmit depends only probability, but essentially independent ALOHA-dependent parameters. Then, light traffic, simple 1 preferred over NCSs. The derived relationship rate, e2e (or bound), accurate realistic can used performance analyses.