Apurva S. Gowda

Towards Green Optical/Wireless In-Building Networks: Radio-Over-Fiber

Energy efficiency has become a major paradigm in the design and operation of future telecommunication networks. Recent studies show that the aggregate power consumption of in-building IT networks (residential and office) is massive and comparable with that of data centers due to the large number of buildings. In this paper, we analyze the energy efficiency of next-generation in-building IT networks to deliver high-speed mobile access to end users via integrated optical/wireless networks using Radio-over-Fiber (RoF) technology. Based on a validated energy efficiency model, our results show that although individual point-to-point RoF links are not as energy efficient as legacy Baseband-over-Fiber links, RoF networks may actually be more energy-efficient when designed keenly with small cells sizes and when the static energy consumption of the remote units is above a particular threshold. Under the assumptions used in this paper, we show that the DRoF-based architectures can be designed to more energy efficient for cell sizes <;17 m.

How to design an energy efficient fiber-wireless network

We analyze the energy consumption of current in-building networks and show that new network designs employing fiber-wireless technologies could lead to significant energy savings in future high-speed networks.

Green in-building networks: The future convergence of green, optical and wireless technologies

The global network energy consumption is increasing at an alarming rate due to proliferation of the Internet and its increasing bandwidth-intensive applications. In this paper, we propose an energy efficient Access/In-Building architecture that features energy efficient customer premises equipment (CPE) design in conjunction with an energy efficient access network protocol, and in-building optical/wireless integration using Radio-over-Fiber. We analyze the energy consumption of the proposed architecture and show that the use of these technologies could lead to up to 50% energy savings compared to the architectures that employ legacy technologies.

Energy consumption of indoor radio-over-fiber distribution links: Experimental findings

Radio-over-Fiber (RoF) based network architectures would allow centralization of signal processing and signal conditioning functions and simple, cost-effective remote units at the cell site. RoF technology results in remote units with few components, however, certain aspects of the technology may inadvertently lead to high power consuming components. In this paper, we experimentally investigate the effect of electrical-optical-electrical (E/O/E) loss and signal bandwidth on the energy consumption of analog and digitized RoF (ARoF and DRoF) links. We also analyze the energy efficiency of multiple services on a single RoF distribution network. Our results show that E/O/E loss significantly degrades the energy efficiency of the ARoF links. DRoF is robust to the E/O/E loss on the optical link but is affected by the loss due to reconstruction of the radio frequency signal at higher Nyquist zones. We also show that increasing the bandwidth improves the energy efficiency. Finally, we demonstrate that the extra energy savings from having multiple services on a single RoF link depends on the wireless environment.

Green optical/wireless in-building networks: The physics of design

Energy efficiency is rapidly becoming an important requirement for modern networks. In this paper, we discuss the physical limits to the power consumption of wireless and optical transmission. We show that there is an optimum cell size that results in the least power consumption in optical/wireless in-building networks and explain why. We then discuss the principles that govern the design of in-building Radio-over-Fiber (RoF) distribution networks. We use theoretical models to analyze the impact of key design factors on the energy consumption of point-to-point RoF links and how their adverse effects can be mitigated. Finally, we compare the energy consumption of several key in-building optical/wireless architectures based on several different RoF technologies, and demonstrate that centralized architectures based on RoF links can be substantially more energy efficient than baseband-over-fiber (BoF) architectures in network capacity-limited scenarios, when designed properly. Our findings also show that RoF-based architectures are energy efficient for cell sizes less than 10m.

Energy-efficient indoor networks

With the growing popularity of high-performance computing devices such as tablets and smart-phones, and the growing trends of cloud-based services, forecasts indicate that the majority of Internet traffic will originate from inside of the buildings. Thus indoor network infrastructure needs to provide both better capacity and better coverage. Meanwhile, energy efficiency of the network becomes an additional requirements on the network design, due to the rising concern of the carbon footprint of telecommunication industry over the past few years. In this paper, we discuss a few fundamental trade-offs that need to be considered when designing energy-efficient networks. We also discuss the energy efficiency of Radio-over-Fiber (RoF) links and compare RoF-based architectures with legacy Baseband-over-Fiber (BoF) for two scenarios: growing network capacity and improving network coverage. We demonstrate that the understanding and the analysis of main energy hogs and their trade-offs in various network architectures is a key factor in optimizing the design of energy-efficient network architecture.

Delay analysis of mixed fronthaul and backhaul traffic under strict priority queueing discipline in a 5G packet transport network

Virtualization of the base station for the purpose of centralization is being actively studied and researched as an implementation option for 5G mobile networks. Proposed as Cloud radio access network, the technology is expected to facilitate easier operation and maintenance than regular radio access networks. However, the base stations traffic has stringent delay requirements. In this paper, we explore the possibility of multiplexing fronthaul traffic and traditional backhaul traffic as it traverses over the metropolitan network while keeping the average fronthaul queueing delay and jitter under control. We analyze and simulate the cases of a single fronthaul flow and multiple fronthaul flows arriving at the packet switch assuming strict priority for the fronthaul queue. We propose a fronthaul frame aggregation strategy to improve the packet transmission efficiency while keeping the average fronthaul queueing delay and jitter constant regardless of the percentage of fronthaul traffic. While the criteria for aggregation is different for the 2 cases, we show that the optimal number of basic frames to aggregate is between 3-10 frames assuming the Common Public Radio Interface protocol.

Small networks, large energy: New frontiers in green IT

This paper examines the energy needs of the world IT infrastructure. We show that small networks, such as intra-building and access networks, consume more energy than large networks. We also examine topologies and technologies that can improve the energy efficiency of the foregoing small networks.

Quasi-Passive Optical Infrastructure for Future 5G Wireless Networks: Pros and Cons

Abstract—In this paper, we study the applicability of the quasi-passive reconfigurable (QPAR) device, a special type of quasi-passive wavelength-selective switch with flexible power allocation properties and no power consumption in the steady state, to implement the concept of reconfigurable backhaul for 5G wireless networks.We first discuss the functionality of the QPAR node and its discrete component implementation, scalability, and performance.We present a novel multi-input QPAR structure and the pseudo-passive reconfigurable (PPAR) node, a device with the functionality of QPAR but that is pseudo-passive during steady-state operations. We then propose mesh and hierarchical backhaul network architectures for 5G based on the QPAR and PPAR nodes and discuss potential use cases. We compare the performance of a QPAR-based single-node architecture with state-of-the-art devices. We find that a QPAR node in a hierarchical network can reduce the average latency while extending the reach and quality of service of the network. However, due to the high insertion losses of the current QPAR design, some of these benefits are lost in practice. On the other hand, the PPAR node can realize the benefits practically and is the more energy-efficient solution for high reconfiguration frequencies, but the remote optical node will no longer be passive. In this paper, we discuss the potential benefits and issues with utilizing a QPAR in the optical infrastructure for 5G networks.

Fiber-based solutions for in-door multi-Gbit/s wireless access

Growth of wireless technologies requires high-capacity and energy-efficient infrastructures. Fiber-based RoF solutions provide multi-Gbit/s capacity with easy-upgrade, cost-effective and energy efficient features.