A Survey on OFDM-Based Elastic Core Optical Networking <s> 2) Flexible Optical WDM (FWDM) <s> The sustained growth of data traffic volume calls for an introduction of an efficient and scalable transport platform for links of 100 Gb/s and beyond in the future optical network. In this article, after briefly reviewing the existing major technology options, we propose a novel, spectrum- efficient, and scalable optical transport network architecture called SLICE. The SLICE architecture enables sub-wavelength, superwavelength, and multiple-rate data traffic accommodation in a highly spectrum-efficient manner, thereby providing a fractional bandwidth service. Dynamic bandwidth variation of elastic optical paths provides network operators with new business opportunities offering cost-effective and highly available connectivity services through time-dependent bandwidth sharing, energy-efficient network operation, and highly survivable restoration with bandwidth squeezing. We also discuss an optical orthogonal frequency-division multiplexing-based flexible-rate transponder and a bandwidth-variable wavelength cross-connect as the enabling technologies of SLICE concept. Finally, we present the performance evaluation and technical challenges that arise in this new network architecture. <s> BIB001 </s> A Survey on OFDM-Based Elastic Core Optical Networking <s> 2) Flexible Optical WDM (FWDM) <s> We propose the flexible optical WDM network architecture, and introduce the routing, wavelength assignment, and spectrum allocation problem in transparent FWDM networks. Spectrum and cost efficiency are improved compared to fixed grid networks. <s> BIB002 </s> A Survey on OFDM-Based Elastic Core Optical Networking <s> 2) Flexible Optical WDM (FWDM) <s> We propose a network model based on format-versatile transceiver for data-rate tunability. We estimate each format's resistance to degradations and dimension a backbone network accordingly, yielding 20% savings on resources compared to single-rate networks. <s> BIB003
The FWDM network architecture was proposed in BIB002 , and is capable of dynamic allocation of network resources, in particular the optical spectrum. It supports optimized spectrum efficiency through elastic channel grids and flexible spectrum allocation for different data rates. While FWDM has a similar concept of flexible spectrum allocation and data-rate-variable optical path as SLICE, its main difference is that FWDM evolved from the current WDM Fig. 11 . Scopes of SLICE BIB001 , FWDM BIB002 , and Data-Rate Elastic Optical Network BIB003 network architecture, allowing single-carrier modulation as well as OFDM-based multi-carrier modulation schemes. Using single-carrier or multi-carrier modulation schemes may lead to some differences in the data-rate/bandwidth-variable transponder and the transmission system design. Similar to SLICE, network nodes need to be upgraded to spectrumvariable WXCs in the FWDM architecture, and their network planning technologies are equivalent, in general.