July 2008 | Volume 11/ Number 7
By: Richard “Zippy” Grigonis
The word “broadband” for business was until recently synonymous with fixed-line, unchannelized T-1s, Primary Rate Interfaces and DSL. At home, one had the choice of either “cable” or ADSL. Now, however, there are many broadband alternatives, including Metro or “Carrier” Ethernet and nascent Broadband over Powerline (BPL) technologies.
Not so many years ago, we would in these pages be extolling the wonders of ATM (Asynchronous Transport Mode), a technology that was surely destined to run everywhere from the WAN to the LAN. But, as things turned out, the present and future appear to belong to Ethernet, in particular so-called Carrier Ethernet, the high bandwidth Ethernet for Metro Area Networks (MAN). It is more commonly known as Metro Ethernet, since the core is still dominated by MPLS, not Ethernet (at least, not yet). “Carrier” denotes a carrier-class service, taking the positive characteristics of Ethernet and strengthening them so that they are suitable for long-range, high traffic volume usage. It’s basically the same plug-and-play Ethernet and physical Ethernet interface you’ve dealt with for decades. The Metro Ethernet Forum (News - Alert) (MEF) is the pertinent standards organization, having a Carrier Ethernet Certification Program to accelerate the delivery of industry standard products and services to the end user.
Extreme Networks (News - Alert) is one of the major players that designs, builds, and installs Ethernet infrastructure solutions for enterprises and service providers. Converged networks built with their equipment support voice, video and data, over a wired and wireless infrastructure. Extreme Networks recently announced the availability of its complete Provider Backbone Bridging — Traffic Engineering (PBB-TE) solution that spans the edge of the network through the metro core. (The PBB-TE technique can transport Carrier Ethernet services, thus natively extending Ethernet across a provider’s network rather than employing other technologies such as SONET/SDH or MPLS.) Extreme Networks’ solution is comprised of new software and hardware, as well as a strategic relationship with their control plane partner, Soapstone Networks (News - Alert).
Even more recently, as we were going to press, Extreme Networks performed a live demo of the kind of network utilization improvements you can achieve with their new PBT-to-MPLS interworking capability. Aside from the service interworking capabilities of their BlackDiamond® 12000 series carrier Ethernet switches, the demo showcased automated service creation using Soapstone’s PNC control plane and highlighted the fast-failover capabilities of the PBT solution.
Matisse Networks (News - Alert) has also entered the fray, re-engineering the last-mile optical world to make it Ethernet-friendly. Their EtherBurst technology, claimed to be the world’s first Packet WDM System, is designed specifically for scaling metro and campus networks. Their system consists of the SX-1000 Ethernet Service Node (these nodes serve as both a local Ethernet switch and the on-ramp to the packet WDM photonic layer), the PX-1000 Photonic Node (these nodes are deployed in a metro ring, and provide a fully automated optical layer, enabling incremental scaling) and the MatisseView Management System, which provides unified access to integrated optical and packet service management software.
Broadband Over Powerline
BPL — Broadband over power lines, also known as “power-line Internet” or “powerband”, is a form of PLC, or Power Line Communication, also known as power line carrier, mains communication, PLT (Power Line Telecom), or PLN (Power Line Networking). It provides Internet access (and IPTV (News - Alert)) via ordinary power lines by connecting a BPL modem-like device into any outlet of a suitably-equipped building and overlaying over the existing power cables electromagnetic waves having undergone OFDM (Orthogonal Frequency-Division Multiplex, a modulation technique wherein blocks of symbols are sent in parallel by employing a large number of orthogonal sub-carriers).
In theory, any location not served by conventional cable or xDSL is nevertheless almost certainly connected to a power grid, along with the electronic devices intended to be connected to the Internet.
Electrical power in the form of alternating current travels over long high voltage transmission lines, is distributed over medium voltage lines, and then the voltage is “stepped down” further locally for use inside buildings. Power line systems have been developed to transmit high bandwidth Internet data over and through each of these systems. Systems have been tested up to 200 Mbps by Consolidated Edison, Duke Energy (and Cinergy), FirstEnergy, National Grid, and Austin Municipal. BPL’s adherents claim that it is more secure and robust than wireless technology. Less expansive BPL-based signaling has been used for “Smart Grids” used by electricity utilities for grid management applications such as advanced remote metering, outage management, preventive maintenance, asset management and optimization and load management and control. Indeed, there are some experts who believe that the future growth BPL is directly tied to Smart Grid development. A successful Smart Grid combines two-way high-speed communications, advanced sensing technology, 24/7 monitoring and enterprise analysis software and related services to provide location-specific, real-time actionable data to all of a utility’s departments.
One section of the U.S. Government’s Energy Independence and Security Act of 2007 specifically promotes Smart Grid development and it requires both the federal and state governments and regulators to take specific actions to support the implementation of a Smart Grid. According to the U.S. Department of Energy and the Electric Power Research Institute, by 2025, the use of a Smart Grid on a portion of the U.S. electric transmission and distribution system could reduce electricity consumption by 5 percent to 10 percent, save consumers more than $50 billion over the next 20 years via a reduction in power outages, and reduce carbon dioxide emissions by up to 25 percent.
BPL can in theory easily support Smart Grid applications, since it has certain advantages over competing wireless systems (e.g., it can monitor and control sensors and switches in both overhead and underground environments). Oncor Electric Delivery Company has the world’s largest Smart Grid (serving 1.8 million homes and businesses) in Dallas, Texas, and Xcel Energy (a U.S. electric and natural gas company, serving customers in eight states with over three million electric customers) is building its Smart Grid City project in Boulder, Colorado, all constructed with equipment from CURRENT Technologies. The CURRENT Smart Grid™ solution is used by utilities worldwide. For example, CURRENT is working on a European Union-sponsored project led by Iberdrola, the world’s fourth largest electric utility, to use Smart Grid technology for EU electric utilities.
CURRENT Technologies can also provide high bandwidth Internet-based services over the same network as its Smart Grid services via its IP-based CURRENT Broadband® technology. Data, voice and video services can be delivered to residential and business users both directly and through wholesale channels. Utilities can also provide information to customers about their electric usage and allow customers to manage thermostats and other devices. CURRENT can also provide Quality of Service (QoS) solutions and you can remotely troubleshoot the network. Additional computers and other devices can be added to the network simply by plugging in another modem, eliminating the complexity of a home network or routers.
CURRENT Broadband users can send data up to 10 times faster than typical DSL or cable modem services, making it suitable for interactive games, high-bandwidth, web-based applications and the transmission of heavy volumes of digital content to the Internet, such as graphics, videos or music.
Another company, Corinex Communications, offers their AnyWire Connectivity technology, often used to leverage use of existing electrical distribution lines, twisted pair copper wires, and coaxial infrastructures, to deliver data, voice, video and broadband applications at up to 200 Mbps.
Corinex has simplified the design and architecture of Access BPL networks by utilizing the frequency division domain exclusively. They operate in a flat layer 2 architecture (Ethernet level) so that BPL deployments using their technology are kept simple and scalable and achieve better line utilization than ixed topologies. Corinex’s Access BPL technology supports Quality of Service (QoS) for VoIP, 3DES security, VLAN tagging, remote management, and programmable frequency notching to comply with any regulations and ensure amateur radio bands are not disturbed.
The Corinex BPL Regenerator (repeater across transformers) was designed with 200 Mbps technology and operates at real world speeds of up to 85 Mbps. Each Regenerator supports up to 32 users on the low voltage side, with the medium voltage backbone supporting up to 2,048 simultaneous users. The units come complete with a Corinex BPL motherboard, one low voltage BPL module, two medium voltage BPL modules, a hardened weatherproof enclosure, RF cables, power cables, power connector, grounding plate/lug, and coaxial connectors. The Regenerators are fully assembled and tested and the enclosure has a removable lid to accommodate easy installation and connections to low and medium voltage lines during deployment. Their couplers do not require a utility to bring the power down for installation.
Founded in 1999, MainNet provides BPL/PLC systems and solutions, enabling intelligent broadband access and Smart Grid applications over any electrical network. Their customizable end-to-end broadband access solutions are controlled by a web-based network management system. MainNet uses dynamic smart repeaters that are designed to create a “noise-free” environment capable of delivering clear voice, data and video services over long distances. Their “secret sauce” involves not simply relying on OFDM modulation, even though OFDM modulation detects changes within the powerline and maintains network communication, even during power spikes or other powerline disruptions. MainNet says this has proved to be insufficient for maintaining a broadband network delivering high-speed data that is subject to frequent changes, both in terms of the number of users and the bandwidth consumption. MainNet instead enhances the technology to support not only the physical layer, but also layer 2 and the application layer (layer 7). It’s PLUS solution is a combination of algorithms and mechanisms adapted from wireless and wireline technology, involving a combination of three additional communication methods:
1. CSMA/CA (News - Alert) (Carrier Sense Multiple Access/Collision Avoidance), designed for data transmission where reliable collision detection isn’t possible — such as in powerline communications. Performance improvement is achieved by reducing the probability of collision and retry. CSMA/CA improves line performance and data throughput, but it can increase data latency, so MainNet has also implemented special QoS mechanisms to enhance performance of such jitter-sensitive applications as voice and video.
2. Smart Repetition. Dynamic repeaters are installed sporadically over the network, obviating the need for complex network planning or costly maintenance. MainNet’s Smart Repetition mechanism that allows each unit to choose the best route to achieve the best performance.
3. Access Hopping. Changes in wire conditions and bandwidth fluctuations are countered by MainNet’s patented Access Hopping (AH) mechanism that uses a network cell topology reminiscent of those employed in cellular phone networks, where each mobile phone automatically migrates between base stations. This AH mechanism enables dynamic routing of up to 1,000 connected users in a single cluster, while maintaining high-frequency bandwidth. Each cluster of customer premises units (NtPLUS) is connected to a single concentrating unit (CuPLUS). In the event of a noisy electrical grid or an overloaded network, the AH mechanism allows any PLUS unit to automatically “hop” between CuPLUS units, thus avoiding speed loss and maximizing bandwidth sharing efficiency.
However, there are still some major questions over what BPL can do under large-scale, real-world conditions. Powerlines are notoriously “noisy”, which can reduce the effective bandwidth. Another concern is that BPL signals traveling over unshielded power lines will radiate away and cause interference and problems with ham radio enthusiasts. This has generally been discounted — except by ham radio operators, who have sued the U.S. Government. Moreover, BPL has no availability during blackouts and disasters when it’s most needed. Serveral years ago, the city of Burbank, California, looked at both WiFi (News - Alert) and BPL municipal systems and decided to go with WiFi.
BPL has had a faster adoption rate in Europe than in the U.S. because of a quirk in the design of their respective power networks. BPL signals do not easily pass through transformers, owing to the high-frequency filtering effects of their high inductance, so signal repeaters must be collocated and attached to the transformers. Now, in Europe, a single step-down transformer serves 10 to 100 homes at a time. In the U.S., however, many smaller, less expensive transformers hang on poles, serving only an average of five homes per transformer. American power networks thus need far more BPL repeaters (at greater expense) than European systems. However, BPL could still be used as a backhaul for WiFi mesh or WiMAX (News - Alert) wireless networks.
For example, Amperion offers Amperion PowerWiFi™, a complete hybrid BPL and WiFi end-to-end network solution. Standard WiFi is used to distribute broadband services into a customer’s home or business, which is said to be less costly per home or business passed than BPL-only solutions. With WiFi as the customer’s access point, the MV (Medium Voltage) to LV (Low Voltage) transition, and the associated cost of the MV/LV gateway equipment, is eliminated. There is no need for dedicated CPE installations at the customer premise either. Adding customers after the initial PowerWiFi network deployment requires no additional capital equipment and can even be done remotely. That’s in stark contrast to many BPL-only solutions which demand installation of a MV/LV gateway unit at every transformer with every new cluster of homes served. Amperion’s technology essentially creates WiFi hotspots that cover cell areas of 700 feet around every pole. While BPL is used as the last mile access backbone, PowerWiFi units can be deployed beyond the MV grid to increase the total coverage area in any direction. The WiFi capability also enables wireless hops (using secure WDS) across separate electric grid segments.
One interesting aspect of Amperion PowerWiFi is that it utilizes WiFi as a failover mechanism to ensure data delivery in cases of temporary interference on the MV line. The switchover between powerline and wireless hops is seamless and completely transparent to the user.
Another fascinating transmission technique for BPL over single uninsulated wires involves microwave frequencies transmitted via a surface wave propagation mechanism called E-Line. In an E-Line system, “launching horns” couple to and from a radially-symmetric planar wave propagating in the space around a single conductor, yielding low attenuation, high bandwidth, high propagation velocity and confining nearly all of the propagated energy quite close to the conductor surface. Such systems can potentially run at symmetric and full duplex bandwidths exceeding 1 Gbps in each direction. Multiple WiFi channels with simultaneous analog television in the 2.4 and 5.3 GHz unlicensed bands have been demonstrated operating over a single medium voltage line. Since E-Line technology can operate anywhere in the 100 MHz to 10 GHz region, it avoids shared spectrum interference issues while offering flexibility for modulation and protocols of a microwave system. Thus, uninsulated single or multi-strand overhead power conductors can now support very low attenuation propagation over the entire frequency range from below 200 MHz to above 10 GHz while employing a launch device of only 15-20 cm in diameter. It’s performance characteristics are second only to optical fiber.
Corridor Systems has used this E-Line technology to offer low-cost solutions for high-performance transport across many miles of overhead powerlines for information-carrying RF signals, be they cellular antenna signals, WiFi, encoded Ethernet, or TDM (T1, T3, etc). Mobile carriers can use this as part of a strategic migration path from 2G/3G to include other fixed-wireless services.
Next month we’ll take a look at the even more bewildering world of Wireless Broadband Alternatives… IT
The following companies were mentioned in this article:
Corinex Communications (www.corinex.com)
Corridor Systems (www.corridor.biz)
Current Technologies (www.currenttechnologies.com)
Extreme Networks (www.extremenetworks.com)
MainNet Communications (www.mainnet-plc.com)
Matisse Networks (www.matissenetworks.com)
Soapstone Networks (www.soapstone.com)
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