## 3 The Third Industrial Revolution (TIR) and Energy Internet
These investments enable utilities and/or municipalities to (i) leverage their existing duct, sewer, and other infrastructure; (ii) create a new source of revenue in the face of ongoing liberalization of the energy sector, particularly in smart grid solutions; and (iii) provide services completely independent from incumbents' infrastructures. Furthermore, it was recently shown in [46] that cooperation among different utilities in the roll-out phase may drive down the CAPEX of FTTB/H deployments by 17%. Innovative partnerships enable utilities and other players to share smart grid communications infrastructures investments by transitioning from the traditional vertical network integration model towards splitting the value chain into a three-tier business model that consists of network infrastructure roll-out, network operation/maintenance, and service provisioning [45]. One of the most promising examples of such a multi-tier business model is the Swiss Fibre Net of OPENAXS, an association of currently 22 regional electricity utilities throughout Switzerland (see also www.openaxs.ch). The goal of Swiss Fibre Net is to create added value for consumers by having 30% of FTTB/H connected households by 2013 and 80% by 2020. The power utilities are responsible for the installation of the network infrastructure as well as its operation and maintenance, but leave its access open to all (e.g., triple-play voice, video, and data) service providers on a nondiscriminatory basis. Another interesting example is the recent interest of Chinese utility companies, e.g., State Grid Corporation of China (SGCC), in PON equipment to not only backhaul electric data on usage and outages of their power networks but also, and arguably more interestingly, to offer FTTH services to consumers and businesses. \"China's smart grid drive creates $1.5 billion opportunity for PON vendors, says Ovum\". A plethora of wired and wireless networking technologies exists to realize smart grid communications infrastructures [47]. It is important to note, however, that in general the goal of utilities is to use only a small number of low-cost, simple, reliable, and future-proof smart grid communications technologies that remain in place for decades after installation. It is also worthwhile to mention that IEEE P2030, one of the first smart grid standards, does not specify any communications technology of choice for the future smart grid gradually evolving between now and 2030, though it is favorable to rely on the exceptionally low latency characteristics of fiber optic facilities, either owned or leased by the smart grid operator, and wireless technologies, where fiber is available to some but not all points in the system [48]. In [49,50], we recently described a variety of advanced techniques to render NG-PONs and converged bimodal FiWi broadband access networks _dependable_, including optical coding based fiber fault monitoring techniques, localized optical redundancy strategies, wireless extensions, and availability-aware routing algorithms, in order to improve their reliability, availability, survivability as well security and safety. Recall from above that beside reliability, _latency_ is a key requirement of not only smart grid communications but also LTE-A fiber backhaul infrastructures. Toward this end, we elaborate on various techniques to lower the latency of NG-PON based smart grid communications and mobile backhaul infrastructures in the following. Low-Latency Techniques for NG-PON Based Smart Grid Communications and Mobile Backhaul Infrastructures  
The integration of LTE and IEEE 802.3 av 10G-EPON networks was studied in [51], where 10G-EPONs are used as the backhaul to LTE with the objective to enable intercommunication between neighboring BSs, which are attached to collocated ONUs, via LTE's X2 interface. The authors proposed the following three integration architectures: (i) native 10G-EPON/LTE integration architecture (NGLIA); (ii) loopback integration architecture (LIA); and (iii) remote node integration architecture (RNIA).