International Core Journal of Engineering 2020-26 | Page 118

2019 International Conference on Artificial Intelligence and Advanced Manufacturing (AIAM) Application of Optical Physical Layer Network Coding on Passive Optical Interconnection Jialong Chen Maoguo Cai Ning Chen College of Electronics and Information Engineering Shenzhen University Shenzhen, China [email protected] College of Electronics and Information Engineering Shenzhen University Shenzhen, China [email protected] College of Electronics and Information Engineering Shenzhen University Shenzhen, China [email protected] and decoding operation. The codec operation can be completed in the optical domain, which reduces the complexity of signal processing of electrical decoding and the network delay caused by photoelectric conversion. However, due to its poor stability and space demanding size, the cross-phase modulation based SOA-MZ interferometer mentioned in [4] and [5] is not suitable to use in top-of-rack (ToR). In addition, the two input signals and the control signal have different wavelengths, which greatly increase the pressure of the ToR wavelength distribution. The Saganac- based all-optical XOR gate is stable due to the symmetry structure mentioned in [6], which can suppresse noise caused by thermal, acoustic, etc. It is smaller in size and lower in switching power thanks to the introduction of highly nonlinear photonic crystal fibers. The wavelength resource will not be occupied much since the input signal wavelength of the logic gate is the same. In the case that might occur a wavelength resources shortage, the dynamic allocation wavelength algorithm mentioned in [7] can resolve the wavelength resource usage problem between certain servers. We propose to replace the traditional PNC algorithm in [7] with the saganac interferometer-based all-optical XOR gate, which can reduce the delay caused by complex signal processing in the electrical decoding operation. Encoding and decoding are evaluated via simulations in transmission rate of 20 Gb/s, it is proved that both synchronous and asynchronous can be realised in an error-free operation. Abstract—The physical layer network coding (PNC) technology is introduced into the optical network in this article. The proposed scheme employs all-optical XOR logic gates that rely on cross-phase modulation-based saganac interferometer fiber optic rings to perform encoding and decoding. The encoding and decoding operations are respectively applied to the coupler and the server of the data center passive optical interconnect structure, which increases the throughput of information exchange. Complex signal processing operations are replaced by optical XOR, which effectively reduces the delay. The scheme has been tested for error-free simulation of synchronization and asynchronous in transmission rate of 20- Gb/s. Keywords—physical layer network coding; passive optical interconnect; saganac interferometer fiber optic rings; error-free simulation I. I NTRODUCTION With the rise and popularity of the applications such as mega data, cloud computing and social networking, global data flow has been grown tremendously. As a key link in information transmission, data center plays an important role in the global network. The network exchange part of data center is still heavily depend on commercial switches. Data center energy consumption and latency are greatly increased due to the mass photoelectric conversion. Therefore, new interconnect architectures and switching technologies are necessary to meet the current challenge. Rack Server A In order to improve the information exchange efficiency and capacity of data center, Physical Layer Network Coding (PNC), as an emerging methodology, has drawn much attention. The crosstalk between the two signals is utilized by the PNC to realise the codec operation, which improves the efficiency and throughput of information exchange. In [1], it is proposed to construct a private virtual network by using PNC, a remote node is set as a relay to couple and broadcast user signals. The signals of two users are simply coupled in the optical domain, then decoded in the electrical domain after photoelectric conversion at the receiving end. The solution for asynchronous isn’t given in the article. The solution for asynchronous by changing the package preamble of the IEEE 802.11 standard are presented in [2] and [3]. Although the specific system design is given and verified experimentally in [3], however, complex signal processing operations are required during electrical decoding. In [4] and [5], Semiconductor Fiber Amplifier-Mach Zehnder interferometer is introduced as a tool to perfrom the encoding 978-1-7281-4691-1/19/$31.00 ©2019 IEEE DOI 10.1109/AIAM48774.2019.00026 Server 1 Buffer XOR D AB ͰD BA Rx ¬ 1 Tx Server 2 ¬ 1 D AB (N+1)*(N+1) Coupler Server N Tx Tx Buffer Rx Dec Coupler XOR D BA Server B ONI ¬ 1 ¬ 1 Buffer XOR Rx D AB ͰD BA (a) (b) Fig. 1. (a) Passive optical interconnect structure on the ToR; (b) duplex transmission PNC-based between a pair of servers. II. C ONCEPT O VERVIEW A. Architecture Fig.1 (a) opposes the proposed the passive optical inter- connection structure on the ToR, where N represents the 96