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SUMMARYWe propose an innovative agile crossbar switch architecture called contention-tolerant crossbar, denoted by CTC(N ). Unlike the conventional crossbar and the crossbar with crosspoint buffers, which require complex hardware resolvers to grant one out of multiple output requests, CTC(N ) can tolerate output contentions by a pipelining mechanism, with pipeline stages implemented as buffers in input ports. These buffers are used to decouple the scheduling task into N independent parts in such a way that N schedulers are located in N input ports, and they operate independently and in parallel. Without using arbiters and/or crosspoint buffers that require additional chip area, the CTC(N ) switch is more scalable than existing crossbars. We analyze the throughput of CTC(N ) switch, and find 63% throughput bottleneck. For achieving 100%, we consider two approaches: using internal speedup and using space multiplexing without internal speedup. We prove that 100% throughput can be achieved with internal speedup 2 or using two layers of CTC(N ) fabric mathematically. Our simulation results validate our theoretical analysis.

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Recently, vehicular ad hoc network (VANET) is receiving lots of attentions as this new networking technology is expected to improve our daily driving experience greatly and will enable a number of emerging applications. It is envisioned that the vehicles in VANETs are armed with a number of advanced technologies such as wireless transceiver, video cameras, etc. This paper investigates the potential of the advanced VANET nodes to construct an impromptu surveillance system to surround an area of interest, which can be a city block, such that any suspect of interest leaving the city block can be monitored by a VANET node participating the surveillance system. Such a system can be useful to provide an emergency response system to keep the track of suspects who are leaving the area by walk or by car after committing a crime inside the block, e.g. Boston bombing suspects. We observe that as the network bandwidth is limited, not all vehicles can participate and transmit video to the control center in real time. Therefore, we propose new scheduling algorithms for the VANET nodes, which consider the mobility of each vehicle as well as the network bandwidth and continuously provides barrier-coverage circumventing the city block over a given mission period. Via simulation, we show the efficiency of our algorithms.

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