## 5 Conclusions  
Drawing lessons from the history of optical networks, it is vital to the business of NGOA network operators not to overestimate the expected bandwidth requirements and flood the market with unneeded capacity. Optical (and wireless) access technologies may move into a substantially different direction in the long run than continued capacity upgrades. In fact, in emerging 4G LTE-A HetNets a cellular paradigm shift is required that recognizes the importance of high-speed (fiber) backhaul connections and look into possible backhaul bottlenecks that might deteriorate the achievable performance gains in the wireless front-end. Beside explaining the role of NG-PON1&2 and beyond in realizing high-capacity and low-latency mobile backhaul infrastructures, we elaborated on the implications of the current global crisis and historical recurrence of once-in-a-half-century recessions as turning points, where the benefits of bimodal FiWi networking technologies may be fully realized across the entire economy, thereby offering a vast innovation and growth potential across multiple economic sectors and ushering in a sustainable global golden age. In coming years, power grids in the United States, Europe, and other regions worldwide are expected to undergo major paradigm shifts, calling for reliable and fast smart grid communications infrastructures that rely on wireless technologies and leverage the superior security and immunity features of widely installed PONs in order to create an interactive, integrated, and seamless Energy Internet infrastructure for the TIR economy and a competitive low carbon society. Recently, several major telecommunication service providers started to move into the energy market. On the other hand, utilities and municipalities are increasingly involved in offering FTTH/B coverage to households and businesses. An interesting example for this ongoing convergence is the recent  
Figure 6: Delay performance comparison.  
interest of Chinese utility companies, e.g., SGCC, in leveraging PON equipment for both smart grid and FTTH/B applications, which creates new business opportunities for PON manufacturers and vendors after major FTTX buildouts in China will be completed soon. In this paper, we have touched on network coding and real-time polling techniques to lower the latency in NG-PON based smart grid communications and mobile backhaul infrastructures. We have discussed their respective pros and cons, paying particular attention to their cost-efficient implementation and achievable performance gains. Possible future post NG-PON2 research activities include the integration of wireless and fiber optic sensors, M2M communications for smart grid applications as well as emerging device-to-device (D2D) communications for efficient mobile data offloading, and fiber backhaul sharing among converged cellular, broadband, and sensor networks.  
The author would like to thank [PERSON] and [PERSON] for their major contributions to network coding in NG-PONs. He would also like to thank [PERSON], [PERSON], and [PERSON] for their fruitful collaboration on RTP in next-generation long-reach PONs. This work was supported by NSERC Strategic Project Grant No. 413427-2011.  
The author declares no conflict of interest.