Power consumption of wired access network technologies

Problem statement: Wired broadband Internet access can be realized using various technologies, configurations and protocols. It is widely deployed and able to provide both high data rates and high reliability. These features are of strong importance for many advanced applications. Since the number of broadband subscribers worldwide grows exponentially, the power efficiency of access networks becomes increasingly important. Approach: The aim of this study is to study power consumption of different wired broadband access technologies including both those already widely used and those which are state-of-the-art, but not yet widely deployed. For this purpose, we developed a model for evaluating energy efficiency of wired access networks. The model is presented and applied to study energy efficiency of various access networks such as Hybrid Fiber Coax (HFC), Digital Subscriber Line (DSL), 1 and 10 Gbit/s point-to-point ethernet and Passive Optical Networks (1G-PON and 10G-PON). The metric for energy efficiency we used in this study is energy consumed per bit transmitted. Results: Results of the comparative study on energy efficiency of different access networks are shown and discussed. Additionally, we estimated environmental implications of different access options by means of reductions in Green House Gas (GHG) emissions caused by the electricity consumption of access network infrastructure. Conclusion: We found out that high-speed optical access technologies providing up to 10 Gbit/s per user have the potential to achieve the highest energy efficiency when assuming future broadband Internet access and broad use of advanced services and applications. However, for lower access data rates, 1G-PONs are the most energy efficient access options. Coper-based access technologies provide generally lower energy efficiency than the fiber based solutions. For transferring a large amount of data and when network equipment is switched off during its inactivity times, optical access technologies have the highest potential to reduce GHG emissions caused by the electricity consumption of access network infrastructure.

Network infrastructure plays a key role in the success of added services and in user satisfaction. It is widely accepted that Passive Optical Networks (PON) are the most promising, cost-effective, and high-performance access network solutions. Access networks are also commonly referred to as either ‘the last mile’ by the operators, or ‘the first mile of the network’ in IEEE terminology. The term ’mile’ is often related to the path portion that is used to reach the user from a network node, however access networks go as far as 20 km depending on the technology used. An access network comprises connections between different subscribers and a Central Office (CO), which is attached to the metro or core network. The wired technology deployed varies significantly from one country to another, i.e. Digital Subscriber line (xDSL), based on copper wires; Hybrid Fiber-coax (HFC), and optical fiber. The trends for Next Generation Access Networks (NGA) based on PON are: Wavelength Division Multiplexing (WDM), 10 Gb/s or more, and longer reach/higher splits. NGA must be able to cope with challenges, such as delivering diverse broadband services and facilitating the integration of different technologies. Moreover, NGA should provide higher bandwidths or further reduce the cost of existing delivering services, and serve as backhaul of wireless access networks (WiFi, WiMAX). The last one constitutes a relevant issue for the convergence between wireless and wired technologies.

Dominant broadband access technologies today are Digital Subscriber Line (DSL) and hybrid fiber coaxial (HFC) networks. DSL leads, with global subscribers exceeding 100 million, while cable-modem subscribers worldwide total 55 million in 2005 [1]. Recently, fiber-to-the-home (FTTH) and fiber-to-the-curb (FTTC) scenarios are also on the rise. In all these access networks, optical fiber plays an imperative role. Fiber carries multimedia signals such as video, audio and Internet data with a combination of subcarrier multiplexed radio over fiber (SCM-ROF) and digital baseband formats. Despite the IPTV hype, the most bandwidth hungry video (especially HDTV) is predominantly transmitted in SCM-ROF format. In addition, wireless broadband multimedia access using the ROF technique is also on the rise. Newly released 71-76 GHz, 81-86 GHz, and 92-95 GHz bands for wireless multimedia delivery will trigger wide deployment of ROF technology. Therefore, ROF plays key role in both wired and wireless broadband multimedia access networks [2]. However, there are number of issues in the design and deployment of ROF links for multimedia access. Nonlinearity of the optical modulator (either direct or external); loss due to electrical-optical-electrical conversion and increasing intensity noise are key concerns. Some of our recent work involves with adaptive digital nonlinearity and noise cancelation [3], optical domain reduction in unmodulated carrier [4] and all optical de-multiplexing of closely spaced RF signals by Bragg grating filters [5] and multi system signals over fiber [6].

The potential for sharing infrastructure costs between a large number of customers and the high data rates allowed by optical fibres make passive optical networks (PONs) an attractive solution to the problem of upgrading current copper-based access networks. Optically-amplified, long reach, time division multiple access (TDMA) PONs or 'SuperPONs' offer the potential to further reduce bandwidth transport costs by enabling the direct connection of access networks and inner core networks, thereby eliminating the costs of the outer core/metro backhaul network. The use of dense wavelength division multiplexing (DWDM) could also allow sharing the same feeder fibre and PON head end equipment between a number of such TDMA SuperPONs, each working at different ITU-grid wavelengths. However, a cost effective access solution should employ a customer optical network unit (ONU), which is independent of the PON wavelength, or colorless, in order to reduce the high inventory and deployment costs of using expensive, wavelength-specified sources at the customer. In this paper we demonstrate for the first time the use of a monolithically-integrated, electroabsorption modulator-semiconductor optical amplifiers (EAM-SOAs) as a colorless ONU in a high performance DWDM SuperPON system. These compact devices offer the potential for low-cost optoelectronic integration with other ONU components together with the ability to modulate at rates up to 10Gbps and beyond. We have used this approach to investigate the feasibility of supporting up to 17 SuperPONs from a single feeder fibre and PON head end, each of 100km-reach accommodating 512 users at 2.5Gb/s or 128 at 10Gb/s.

We investigate the challenges in designing the network architecture for running EPON (Ethernet Passive Optical Network) Protocol over Coax, or EPoC in short. EPoC is the transparent extension of EPON over a cable operator's Hybrid Fiber-Coax (HFC) network, and uses a hybrid of optical and coaxial technologies to carry traffic to and from end-users and the Internet backbone. For managing and controlling such a hybrid network, a network operator will prefer to have a unified scheduling, management, and quality-of-service (QoS) environment that includes both the optical and coax portions of the network. This can be achieved by extending the EPON Medium Access Control (MAC) to run over the coax physical layer, to have a centralized end-to-end network control from the cable head-end to the end-users' premises. The use of the coax portion of the network is transparent to EPON protocol operation in the headend, as the same MAC runs over the entire network. In this article, we describe the architecture of EPoC, and outline how the EPON MAC Control, i.e., the EPON Multi-Point Control Protocol (MPCP) can be extended for designing an end-to-end Multi-Point MAC Control for EPoC. We explain the design of several MAC functions and their operation, including framing for coax, Ethernet frame fragmentation, generation of upstream and downstream Media Allocation Plans, and automatic discovery and registration of user equipment. With strong backing from both service operators and equipment vendors, EPoC is set to become a rapidly-evolving standard within the next few years, and the creation of the IEEE 802.3bn Task Force for EPoC is a major step in that direction.

Ethernet passive optical networks (EPONs) have emerged as the one of the most promising candidates for next-generation access networks. These new architectures couple low-cost optics with advanced edge electronics to offer vastly improved scalability over competing digital subscriber line and cable modem offerings. This paper proposes several novel architectural enhancements for EPON, which will help increase the viability of optical access over a broader range of subscriber access scenarios. Specifically, this paper proposes a two-stage EPON architecture that allows more end-users to share an optical line terminal link, and enables longer access reach/distances (beyond the usual 25 km distance). In addition, a new dynamic bandwidth allocation (DBA) algorithm is proposed to effectively allocate bandwidths between end users. This DBA algorithm can support differentiated services in a network with heterogeneous traffic. We conduct detailed simulation experiments to study the performance and validate the effectiveness of the proposed architecture and algorithms.

With the growing interest on wireline network architectures for residential triple-play and business Ethernet services there is a renewed demand for efficient and reliable packet-based transport capabilities between the content providers and the end users. Voice and data traffic carried over a variety of access technologies is collected via technology-specific access networks (e.g., digital subscriber line [xDSL], passive optical network [xPON], and wireless fidelity [WiFi]). Metro and core networks need to aggregate the various user flows from different access network nodes and provide scalable and cost-effective distribution of various flow types (e.g., Internet access, voice, video on demand, and broadcast TV services) to the relevant service access points. Varying quality of service and resiliency requirements for these services are being reflected in a new breed of converged Ethernet and optical network elements with capabilities to interwork the bearer-planes of these two networking technologies seamlessly. Network elements based on Ethernet/Optical converged technology are able to select the most fitting mechanisms from each networking technology to meet the transport requirements for each individual service demand better while providing significantly enhanced implementation and operational efficiencies. This paper discusses network architecture models and network elements addressing these goals. © 2007 Alcatel-Lucent.

In today’s connected world, choosing the right broadband technology is key to delivering fast and reliable internet. This paper takes a closer look at three major players in the field: DSL (Digital Subscriber Line), DOCSIS (Data Over Cable Service Interface Specification), and PON (Passive Optical Network). Each of these technologies uses a different kind of infrastructure—DSL runs over traditional telephone lines, DOCSIS relies on cable TV networks, and PON uses cutting-edge fiber-optic cables. DSL is widely available and cost-effective but struggles with speed over long distances. DOCSIS offers better speeds and is commonly used in cities, though bandwidth is shared among users. PON, on the other hand, delivers ultra-fast speeds and is ideal for future internet demands, but comes with higher installation costs. By comparing their performance, scalability, and costs, this paper helps understand where each technology fits best and how they can meet the growing demands of digital life.

Using proxies to enhance TCP performance over hybrid fiber coaxial networks

Next-generation access/mobile networks have set high standards in terms of providing wireless services at high data rates in order to keep up with the vast demands for other mobility and multiple services. Wireless-optical broadband access network (WOBAN) technology, also known as fibre-wireless (FiWi), has uncovered incredible opportunities for the future of next-generation networks because it gets the best of both domains: huge bandwidth provided by the optical fibre and high ubiquity of the wireless domain. The objective of FiWi networks is to integrate the high data rate and long reach provided by optical networks and the ubiquity and mobility of wireless networks, with the target to decrease their expense and complexity. Multiple-input–multiple-output (MIMO) is an inevitable technique for most of the new mobile/wireless networks that are driven by the huge data rates required by today’s users. Consequently, to construct any FiWi system for next-generation (NG) access/broadband networks, an MIMO technique has to be considered. This article presents a comprehensive, contemporary review of the latest subsystems, architectures and integrated technologies of MIMO wireless signals backhauling using optical fibre or fibre access networks, such as passive optical networks (PONs). An overview for FiWi, PONs and MIMO wireless systems is provided. In addition, advanced techniques of accommodating the MIMO wireless signals over optical fibre are explained and compared. Different types of wireless MIMO signals over fibre, such as 5G, WiFi and related transport technologies, are reviewed. Moreover, future research trends are also discussed.

Radio over Fibre (RoF) technology provides distribution of broadband signals to base station using an optical access network. This technology reduces the complexity at base station. On the other hand, giga bit passive optical network (GPON) has gained much of the interest in today's network due to its high data rate (1.2 GHz-2.4 GHz), simplicity, flexibility and low costs. The combination of GPON with RoF technology provides high capacity and high data rate solution. This paper provides characterization of RoF GPON by various simulations performed on OPTSIM software. The statistical analysis of simulation results are based on received signal strength and eye pattern obtained for various modulation schemes at different distances.

Edge computing provides crucial support to next-generation mobile services that demand high data rates, low latency, and high reliability. The development of high data rate communication has lead to the emergence of cell densification as a key enabler for 5G. Unfortunately, the cost of fiber for backhaul and fronthaul poses hindrance to wide-scale adoption of small cells. Free Space Optics (FSO) offers a cost-effective alternative, though its performance is vulnerable to adverse weather, particularly fog. Recent advances in adaptive optics and automatic steering/tracking have improved FSO reliability by reducing pointing errors and enabling dynamic link reconfiguration, which further supports intelligent traffic diversion and load balancing across edge servers. In this paper, we propose a multi-hop mesh optical access network that integrates fiber-based Passive Optical Networks (PONs) with steerable FSO links to provide reliable and scalable backhaul for dense Radio Access Networks (RANs). A joint optimization framework for dynamic routing and edge server load balancing is developed. Extensive simulations demonstrate that the proposed design ensures fairness, reduces the number of required FSO transceivers, and delivers data rates comparable to established benchmarks.

Optical fibre step by step substitutes existing copper cable infrastructure in the carriers' access networks, enabling new broadband services. One common approach, a passive optical network (PON) infrastructure, basically consists of optical fibres and splitters, which are lit up by G-PON (Gigabit/s-PON) or XG-PON (10 Gigabit/s-PON). These systems are attenuation limited, therefore the loss budget of a PON is of high importance. For the deployment process the total attenuation of the PON, between Central Office (CO, OLT) and customer site (ONT), must be accurately monitored and kept below the values specified in G.984.x and G.987.x standards. In FTTH scenarios the PON attenuation measurements must include the in-house networks up to the subscriber fibre cable termination unit. During operation, the Optical Line Supervision (OLS) parameters (e.g. G.984.2, Amd2) are continuously monitored, processed and correlated for appropriate alarm generation. In the case of a fibre failure, additionally non-intrusive in-service measurements from the CO site must be supported for fault localisation. This is enabled by an appropriate WDM-filter per PON in the CO, providing access to the PON for OTDR measurements at wavelengths of 1625/1650 nm. In this paper possible solutions for PON measurement and monitoring for the deployment and operation of FTTH networks will be described in detail from a carrier's perspective. All these activities must be carried out in a minimum of time and with low operational efforts in order to guarantee a cost efficient network operation.

FiberVista is a fiber-to-the-home (FTTH) or fiber-to-the-curb (FTTC) system that provides more bandwidth for emerging broadband services, such as Internet data, than existing deployed residential systems, while tapping predictable revenue streams from telephony and analog- and digital-video broadcast television service. At the same time, FiberVista minimizes development costs by reusing existing or emerging technology from other systems, such as cable modems and low-cost residential optical transceivers. It also allows for incremental, “pay-as-you-grow” provisioning of capacity. Like cable-television (CATV) hybrid fiber-coax (HFC) networks, FiberVista uses subcarrier multiplexing to offer a flexible mix of services. The system is superior to HFC in that it offers more total bandwidth, both upstream and downstream, which can be shared among fewer homes. By limiting the coax plant to a small passive run in FTTC, or eliminating it altogether in FTTH, FiberVista minimizes the most unreliable and maintenance-intensive portion of the HFC network. Furthermore, it utilizes new technologies, such as high-power erbium-doped fiber amplifiers (EDFAs), coarse wavelength division multiplexing (CWDM), and passive optical networks (PONs), to make the extension of optical fiber deep into the network practical. In this paper, we describe the FiberVista network architecture, potential upgrade scenarios, and experimental system demonstrations.

Multiple Input Multiple Output (MIMO) communication technology has received recently significant attention triggered by the rapid development of Orthogonal Frequency Division Multiplexing (OFDM) broad-band wireless and high speed wireline communication systems. Such systems are very sensitive to Narrowband Interferences (NBI) due to their relatively low transmission power. This type of signal interference can be found in the new unlicensed frequency bands, e.g., the Industrial Scientific Medical (ISM) band, coming from systems such as Bluetooth or microwave ovens which interfere with OFDM based Wireless Local Area Networks (WLAN), like Hiperlan II. Other examples of NBI, typical for Digital Subscriber Line (DSL) communications, are strong Radio Frequency Interferences (RFI) from short-wave radio, Citizen's Band (CB) radio and amateur “ham” radio which interfere with Hybrid Fiber Coaxial (HFC) networks and high speed DSL. Ineffective shielding of a cable network may also cause the ingress from external home electrical devices, such as cordless phones, TVs and computers. Let’s consider a strong NBI signal which resides within the same frequency band as a wideband OFDM signal. In this case, severe Signal to Noise Ratio (SNR) degradation is likely to occur across all OFDM subcarriers due to spectral leakage of the NBI signal from block processing in the OFDM receiver. In Fig. 1, the magnitude-squared of the received