Evolution of data centers: A critical analysis of standards and challenges for FSO links

As the bandwidth-intensive and performance-sensitive application portfolio broadens, so does the interest in data center networks (DCNs) by network research community. Most DCNs deployed today are wired DCNs in which copper and optical fiber cables are used for communication. Despite recent advances in DCN design, there are two inevitable problems facing wired DCNs; hotspots and cabling complexity. To alleviate these problems, recent research works explore the integration of wireless technologies, such as, free space optical (FSO) communication or 60 GHz radio frequency, into DCNs. Wireless links can be used to augment conventional wired DCNs, or to realize a pure wireless DCN. In this paper, we discuss and analyze challenges that may face FSO-DC designers, and identify standardization needs and opportunities to help accelerate the development of FSO links for DCNs. To this end, we review state of the art of wireless DCNs using FSO links. We also briefly review and summarize physical layer specifications of existing standards related to indoor FSO communication, such as, IEEE 802.11 standard, IEEE 802.15.7 standard for visible light communications (VLC), and the families of standards developed by the Infrared Data Association (IrDA) and the VLC Association (VLCA).