24,366 research outputs found
Crosstalk-free Conjugate Networks for Optical Multicast Switching
High-speed photonic switching networks can switch optical signals at the rate
of several terabits per second. However, they suffer from an intrinsic
crosstalk problem when two optical signals cross at the same switch element. To
avoid crosstalk, active connections must be node-disjoint in the switching
network. In this paper, we propose a sequence of decomposition and merge
operations, called conjugate transformation, performed on each switch element
to tackle this problem. The network resulting from this transformation is
called conjugate network. By using the numbering-schemes of networks, we prove
that if the route assignments in the original network are link-disjoint, their
corresponding ones in the conjugate network would be node-disjoint. Thus,
traditional nonblocking switching networks can be transformed into
crosstalk-free optical switches in a routine manner. Furthermore, we show that
crosstalk-free multicast switches can also be obtained from existing
nonblocking multicast switches via the same conjugate transformation.Comment: 10 page
Modeling and Evaluation of Multisource Streaming Strategies in P2P VoD Systems
In recent years, multimedia content distribution has largely been moved to the Internet, inducing broadcasters, operators and service providers to upgrade with large expenses their infrastructures. In this context, streaming solutions that rely on user devices such as set-top boxes (STBs) to offload dedicated streaming servers are particularly appropriate. In these systems, contents are usually replicated and scattered over the network established by STBs placed at users' home, and the video-on-demand (VoD) service is provisioned through streaming sessions established among neighboring STBs following a Peer-to-Peer fashion. Up to now the majority of research works have focused on the design and optimization of content replicas mechanisms to minimize server costs. The optimization of replicas mechanisms has been typically performed either considering very crude system performance indicators or analyzing asymptotic behavior. In this work, instead, we propose an analytical model that complements previous works providing fairly accurate predictions of system performance (i.e., blocking probability). Our model turns out to be a highly scalable, flexible, and extensible tool that may be helpful both for designers and developers to efficiently predict the effect of system design choices in large scale STB-VoD system
Digital Switching in the Quantum Domain
In this paper, we present an architecture and implementation algorithm such
that digital data can be switched in the quantum domain. First we define the
connection digraph which can be used to describe the behavior of a switch at a
given time, then we show how a connection digraph can be implemented using
elementary quantum gates. The proposed mechanism supports unicasting as well as
multicasting, and is strict-sense non-blocking. It can be applied to perform
either circuit switching or packet switching. Compared with a traditional space
or time domain switch, the proposed switching mechanism is more scalable.
Assuming an n-by-n quantum switch, the space consumption grows linearly, i.e.
O(n), while the time complexity is O(1) for unicasting, and O(log n) for
multicasting. Based on these advantages, a high throughput switching device can
be built simply by increasing the number of I/O ports.Comment: 24 pages, 16 figures, LaTe
- …