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

A fast and efficient crosstalk-free algorithm for routing in optical multistage interconnection networks

In this paper, a fast and efficient crosstalk-free routing algorithm is proposed to enhance message routing in optical multistage interconnection networks (OMINs). The new Fast ZeroXY algorithm is designed based on the Zero algorithms, which uses the time dilation approach to eliminate the negative effect of crosstalk associated with optical switching in the optical Omega network. To evaluate the performance of the new algorithm, a crosstalk-free version of the original ZeroXY algorithm is developed extended from the Improved ZeroXY algorithm, called the Modified ZeroXY algorithm. The Fast ZeroXY algorithm is shown to efficiently route permutations without crosstalk with improved routing time compared to the original crosstalk- free ZeroXY algorithm

Fast ZeroY algorithm for efficient message routing in optical multistage interconnection networks

Limited by the properties of optical signals, it is not possible to route more than one message simultaneously, without optical crosstalk, over a switching element in an Optical Multistage Interconnection Networks (OMINs). One solution, called the time domain approach, avoids optical crosstalk by arranging the permutation in such a way that a set of crosstalk-free connections can be established and each connection set be made active in different time slots. Based on the Zero algorithms, we proposed a fast and efficient crosstalk-free algorithm for message routing in optical Omega multistage networks. The Bitwise Window Method (BWM) is used to identify potential message conflicts that may further lead to optical crosstalk. In addition, the inverse Conflict Matrix (iCM) is used to map identified conflicts between messages in the network. It is shown that the new algorithm successfully improved the execution time in comparison to the original Zero algorithm

Crosstalk-Free Scheduling Algorithms for Routing in Optical Multistage Interconnection Networks

Multistage Interconnection Networks (MINs) have been used in telecommunication networks for many years. Significant advancement in the optical technology have drawn the idea of optical implementation of MINs as an important optical switching topology to meet the ever increasing demands of high performance computing communication applications for high channel bandwidth and low communication latency. However, dealing with electro-optic switches instead of electronic switches held its own challenges introduced by optics itself. Limited by the properties of optical signals, optical MINs (OMINs) introduce optical crosstalk, as a result of coupling two signals within each switching element. Therefore, it is not possible to route more than one message simultaneously, without optical crosstalk, over a switching element in an OMIN. Reducing the effect of optical crosstalk has been a challenging issue considering trade-offs between performance and hardware and software complexity. To solve optical crosstalk, many scheduling algorithms have been proposed for routing in OMIN based on a solution called the time domain approach, which divides the N optical inputs into several groups such that crosstalk-free connections can be established. It is the objective of the research presented in this thesis to propose a solution that can further optimize and improve the performance of message scheduling for routing in the optical Omega network. Based on Zero algorithms, a Modified Zero algorithm is developed to achieve a crosstalk-free version of the algorithm. Then, the Fast Zero (FastZ) algorithm is proposed, which uses a new concept called the symmetric Conflict Matrix (sCM) as a pre-scheduling technique. Extended from the FastZ algorithms, another three new algorithms called the FastRLP, BRLP and FastBRLP algorithms are developed to achieve different performance goals. Lastly, a comparison is made through simulation between all algorithms developed in this research with previous Zero-based algorithms as well as traditional Heuristic algorithms since equal routing results can be obtained between all algorithms. Through simulation technique, all three FastZ, BRLP and FastBRLP algorithms have shown the best results when the average execution time is considered. The FastRLP and FastBRLP algorithms on the other hand have shown the best results when the average number of passes is considered. It is proven in this thesis that the new approach has by far achieved the best performance among all the algorithms being tested in this researc

Interconnection network architectures based on integrated orbital angular momentum emitters

Novel architectures for two-layer interconnection networks based on concentric OAM emitters are presented. A scalability analysis is done in terms of devices characteristics, power budget and optical signal to noise ratio by exploiting experimentally measured parameters. The analysis shows that by exploiting optical amplifications, the proposed interconnection networks can support a number of ports higher than 100. The OAM crosstalk induced-penalty, evaluated through an experimental characterization, do not significantly affect the interconnection network performance