3 research outputs found
Optimizing the Throughput of Particulate Streams Subject to Blocking
Filtration, flow in narrow channels and traffic flow are examples of
processes subject to blocking when the channel conveying the particles becomes
too crowded. If the blockage is temporary, which means that after a finite time
the channel is flushed and reopened, one expects to observe a maximum
throughput for a finite intensity of entering particles. We investigate this
phenomenon by introducing a queueing theory inspired, circular Markov model.
Particles enter a channel with intensity and exit at a rate . If
particles are present at the same time in the channel, the system becomes
blocked and no more particles can enter until the blockage is cleared after an
exponentially distributed time with rate . We obtain an exact expression
for the steady state throughput (including the exiting blocked particles) for
all values of . For we show that the throughput assumes a maximum
value for finite if . The time-dependent throughput
either monotonically approaches the steady state value, or reaches a maximum
value at finite time. We demonstrate that, in the steady state, this model can
be mapped to a previously introduced non-Markovian model with fixed transit and
blockage times.
We also examine an irreversible, non-Markovian blockage process with constant
transit time exposed to an entering flux of fixed intensity for a finite time
and we show that the first and second moments of the number of exiting
particles are maximized for a finite intensity.Comment: 20 pages, 13 figure
Autonomous Discovery and Maintenance of Mobile Frees-Space-Optical Links
Free-Space-Optical (FSO) communication has the potential to play a significant role in future generation wireless networks. It is advantageous in terms of improved spectrum utilization, higher data transfer rate, and lower probability of interception from unwanted sources. FSO communication can provide optical-level wireless communication speeds and can also help solve the wireless capacity problem experienced by the traditional RF-based technologies. Despite these advantages, communications using FSO transceivers require establishment and maintenance of line-of-sight (LOS). We consider autonomous mobile nodes (Unmanned Ground Vehicles or Unmanned Aerial Vehicles), each with one FSO transceiver mounted on a movable head capable of scanning in the horizontal and vertical planes. We propose novel schemes that deal with the problems of automatic discovery, establishment, and maintenance of LOS alignment between these nodes with mechanical steering of the directional FSO transceivers in 2-D and 3-D scenarios. We perform extensive simulations to show the effectiveness of the proposed methods for both neighbor discovery and LOS maintenance. We also present a prototype implementation of such mobile nodes with FSO transceivers. The potency of the neighbor discovery and LOS alignment protocols is evaluated by analyzing the results obtained from both simulations and experiments conducted using the prototype. The results show that, by using such mechanically steerable directional transceivers and the proposed methods, it is possible to establish optical wireless links within practical discovery times and maintain the links in a mobile setting with minimal disruption