Routing, Modulation Format, Baud Rate and Spectrum Allocation in Optical Metro Rings With Flexible Grid and Few-Mode Transmission

Abstract

Application of few-mode transmission (FMT) in transport optical network is currently under scrutiny, especially for metro networks, where shorter distances and pressing traffic increase (e.g., due to a growing need for metro datacenter interconnection) represent promising conditions for FMT deployment. In this paper, we analyze, from a network-level perspective, the benefits introduced by FMT in metro networks. We consider the application in a flexi-grid network of a FMT system employing hybrid optical/digital mode demultiplexer and low-complexity MIMO-based digital signal processing (DSP). Under this system model, we derive the reach values associated to different modulation formats, baud rates, and number of modes. For the first time to the best of our knowledge, we formulate using linear programming the routing, modulation format, baud rate, and mode assignment problem, for two different switching policies (spatially flexible and spatially and spectrally flexible switching). Using our proposed modes, we identify the configurations that ensure minimum spectrum occupation or minimum cost of installed transceivers, and contrast them to the benchmark case of single-mode transmission.

Impact of Spatial and Spectral Granularity on the Performance of SDM Networks Based on Spatial Superchannel Switching

“…Note that the spatial Sp-Ch allocation policy was not investigated in any of these works. In [26], exploiting the spatial Sp-Ch allocation policy, the routing, modulation format, baud rate, and mode assignment problem was addressed with the aim of showing the benefits of FMFs in metro networks. Note that, the two main technology areas limiting channel allocation and routing options in an SDM based optical network are fiber type and switching paradigms.…”

Migration Planning from Elastic Optical Networks to Spectrally-Spatially Flexible Optical Networks

“…The considered SS-FON is composed of SMFBs, where each fiber provides 4 THz bandwidth divided into frequency slices of 12.5 GHz width. We assume that the network is equipped with coherent transceivers, each one operating at a fixed baud rate and transmitting/receiving an optical carrier (OC) that occupies 37.5 GHz (3 frequency slices) [5]. We consider 4 available MFs, namely, BPSK, QPSK, 8-QAM,16-QAM that support bit-rates of 50, 100, 150 and 200 Gbps, since a fixed guardband of 12.5 GHz width is assumed to separate adjacent SChs.…”

Predeployment of Transponders for Dynamic Lightpath Provisioning in Translucent Spectrally–Spatially Flexible Optical Networks

“…A SCh can contain a number of optical carriers (OCs), each using ∆OC frequency slices, where an OC is transmitted/received by one transponder. As proposed in [26] and [27], we assume that ∆OC = 3 slices, what is equivalent to 37.5 GHz. A set of modulation formats M = {m1, …, m|M|} is defined.…”

“…To illustrate the considered B2B regeneration approach and the effect of transponder placement, we consider a simple example shown in Figure 2. We assume four modulation formats, namely, BPSK, QPSK, 8-QAM, and 16-QAM, with the bit rates transmitted by OCs and the transmission reaches of considered modulation formats based on data presented in [26] and [27] and shown in Table 1. A request (lightpath) is allocated on a routing path (a, b, c, d) of an overall length 3800 km consisting of three links: (a, b) 1000 km, (b, c) 2300 km, and (c, d) 500 km.…”

“…In particular, we considered four modulation formats, namely, BPSK, QPSK, 8-QAM, and 16-QAM. Based on the data presented in References [26,27], we assumed that coherent transponders transmitted/received the signals of 3 slices (i.e., 37.5 GHz). The bit rates supported by a transponder depended on the applied modulation format and are presented in Table 1.…”