5 research outputs found
A Multi-Floor Arrayed Waveguide Grating Based Architecture with Grid Topology for Datacenter Networks
This paper proposes a grid topology based passive optical interconnect (POI) architecture that is composed of multiple floors of arrayed waveguide grating routers (AWGRs) to offer high connectivity and scalability for datacenter networks. In the proposed POI signal only needs to pass one AWGR, and thus can avoid the crosstalk accumulation and cascaded filtering effects, which exist in many existing POI architectures based on cascaded AWGRs. Meanwhile, due to high connectivity, the proposed grid topology based POI also has the potential advantage of high reliability. Simulation results validate the network performance. With a proper node degree, the proposed grid topology can achieve acceptable blocking probability. Besides, steady performance is kept when the number of floors increases, indicating good scalability of the proposed POI
Optical Networks and Interconnects
The rapid evolution of communication technologies such as 5G and beyond, rely
on optical networks to support the challenging and ambitious requirements that
include both capacity and reliability. This chapter begins by giving an
overview of the evolution of optical access networks, focusing on Passive
Optical Networks (PONs). The development of the different PON standards and
requirements aiming at longer reach, higher client count and delivered
bandwidth are presented. PON virtualization is also introduced as the
flexibility enabler. Triggered by the increase of bandwidth supported by access
and aggregation network segments, core networks have also evolved, as presented
in the second part of the chapter. Scaling the physical infrastructure requires
high investment and hence, operators are considering alternatives to optimize
the use of the existing capacity. This chapter introduces different planning
problems such as Routing and Spectrum Assignment problems, placement problems
for regenerators and wavelength converters, and how to offer resilience to
different failures. An overview of control and management is also provided.
Moreover, motivated by the increasing importance of data storage and data
processing, this chapter also addresses different aspects of optical data
center interconnects. Data centers have become critical infrastructure to
operate any service. They are also forced to take advantage of optical
technology in order to keep up with the growing capacity demand and power
consumption. This chapter gives an overview of different optical data center
network architectures as well as some expected directions to improve the
resource utilization and increase the network capacity
PAM Performance Analysis in Multicast-Enabled Wavelength-Routing Data Centers
Multilevel pulse amplitude modulation (M-PAM) is gaining momentum for high-capacity and power-efficient cloud computing. Compared to the classic on-off keying (OOK) modulation, high-order PAM yields better spectral efficiency but is also more susceptible to physical layer degradation effects. We develop a cross-layer analysis framework to examine the PAM transmission performance in data center network environments supporting both optical multicasting and wavelength routing. Our analysis is conducted on a switch architecture based on an arrayed-waveguide grating (AWG) core and distributed broadcast domains, exhibiting different physical paths, and random, uncontrolled crosstalk noise. Reed-Solomon coding with rate adaptation is incorporated into PAM transceivers to compensate for impairments. Our Monte Carlo simulations point to the significant impact of AWG crosstalk on higher order PAM in wavelength-reuse architectures and the importance of code rate adaptation for signals traversing multiple routing stages. According to our study, 8-PAM offers the highest effective bit rates for signals terminating in one broadcast domain and performs poorly when considering interdomain connectivity. On the other hand, the impairment-induced degradation of interdomain capacity for 4-PAM can be limited to 20.7%, making it better suited for connections spanning two broadcast domains and a crosstalk-rich stage. Our results call for software-defined PAM transceiver designs in support of both modulation order and code rate adaptation