By Scott Wilkinson
The bottom line of the green imperative in telecommunications is cost savings, which is not necessarily a new concept. What is new is the industry’s collective agreement on a common path to this goal.
Green” has evolved from a buzzword thrown around by environmentalists and politicians into a powerful technical and business driver in telecommunications. Telecommunications companies and personnel now recognize the economic as well as public relations benefits of energy efficiency.
As a result, the green imperative in telecommunications has increased, manifested in green standards, requirements, and new challenges. The challenges are being pushed down from the carriers to the equipment vendors, who are pushing down onto the component vendors, who are pushing the fundamental researchers to come up with new, green solutions to very difficult problems.
At the carrier level, the primary driver for green initiatives is to reduce costs. The public relations benefits are welcome and widely touted, but the bottom line is the bottom line and carriers have recognized the tangible economic benefits of going green. The primary goal of the carrier green initiatives is to reduce energy consumption costs, but this reduction can take many forms.
The most obvious way to reduce energy costs is to reduce the energy consumed by the network elements. Initiatives like Verizon’s TPR 9205, “Energy Efficiency Requirements for Telecommunications Equipment,” place hard numbers on the required reduction in energy consumed per bandwidth provided (among other metrics) with an overall target of 20% energy consumption reduction over 2008 levels. For example, the telecommunications equipment energy efficiency rating (TEEER) for a 40-Gbps transport element would be calculated as follows:
- Throughput: 40Gbps
- Pmax = 2kW
- P50%load = 1150W
- Psleep = 900W
- Pt = 0.35*Pmax + 0.4*P50%load +0.25*Psleep= 1385W
- TEER = -log(Pt / Throughput) = 7.46
Larger numbers are better, and smaller numbers are worse. Note that, according to Verizon’s standards, the minimum allowable TEEER for transport equipment is 7.54, a reduction of 17% from the example shown.
Additionally, there are other energy-reduction initiatives within the carriers that are less immediately obvious. These include:
- requirements to reduce maintenance costs (fewer truck rolls means less energy burned);
- requirements to reduce real
- estate costs (less air conditioning means lower energy bills);
- requirements to reduce operational costs (the more automatic the network, the fewer resources consumed to manage it);
- requirements to reduce materials costs (fewer materials means fewer resources consumed).
Each of these requirements creates additional challenges, especially when one requirement conflicts with another. For example, the requirements to reduce materials and real estate costs become a requirement for denser network elements. However, denser network elements typically require higher power in a smaller area, which conflicts not only with the TEEER requirements, but also with industry standards such as Network Equipment Building System (NEBS).
Carriers are implementing much of their green evolution by putting pressure on their equipment vendors to come up with denser, yet less power-hungry elements. However, the carriers are also taking the initiative to migrate their networks to greener architectures overall, including collapsed networks, passive optical networks (PONs), and automated provisioning.
In a collapsed network, a single network carries all carrier traffic (Figure 1). Traditionally, carriers deployed a Frame Relay network next to an ATM network next to an Ethernet network next to a TDM network. While there was some overlap, the overlap was minimal. New network designs show a single core network based on technologies such as MPLS-TP and OTN that enable a much more efficient overall network architecture. Within the core of the network, traffic is switched at the lower layer of the OSI stack to reduce the need for expensive and power-hungry router ports.
|Figure 1. In the collapsed network concept, most of the traffic can be switched optically and only dropped into an OTN switch when necessary. Most OTN traffic is switched at the OTN layer and only dropped into a common Layer 2 (such as MPLS-TP) switch when necessary. Only a small minority of the traffic is dropped from Layer 2 into the more expensive Layer 3 router|
PONs, meanwhile, are now the access network of choice for most of the major worldwide carriers. Whether fiber to the home (FTTH), fiber to the curb (FTTC), or some other FTTx variant, all carriers recognize the green savings associated with a PON. PONs have no electronics in the field, which reduces not only energy consumption but also real estate, cooling, and maintenance costs—all of which add to the green bottom line.
Automated provisioning, via GMPLS typically, promises an intelligent network that allocates resources as needed with minimal operator involvement. Reducing operator involvement can potentially reduce real estate, truck roll, and equipment requirements, which results in an overall green improvement.
Verizon says it began its green initiative as a way to help define the requirements itself before a standards body or the government defined the requirements for it. AT&T began a similar initiative for the same reason. Starting in July 2008, these carriers were vindicated when the Alliance for Telecommunications Industry Standards (ATIS) launched its green initiative and used the carrier programs as the basis for a universal (at least in the U.S.) standard.
ATIS published a standard that defines what it calls the Telecommunication Energy Efficiency Ratio (TEER) in March 2009. Other than the extra “E,” the ATIS TEER is very similar to the Verizon TEEER. ATIS continues to work on industry standards for green technology, with the initial report from the Exploratory Group on Green, ATIS Report on Environmental Sustainability, released in May 2009. (For more information on the ATIS Green Initiative, visit http://www.atis.org/Green/index.shtml).
Equipment vendor challenges
The emerging carrier-specific, industry-wide green standards for telecommunications equipment pose a significant challenge to network element vendors. Not only do they need to build equipment that uses less power, but the equipment must also operate at higher speeds with more functionality while occupying less space and costing less than previous generations. To meet these requirements, equipment vendors not only are taking advantage of emerging technologies to build smaller and faster equipment, but are also innovating in element design and network concepts.
The multi-service provisioning platform (MSPP) was a very popular concept among startup companies during the telecommunications boom of the last decade. However, most MSPPs—often denigrated as “god boxes”—were never successful with major carriers for a variety of reasons. Recently, the MSPP has arisen anew as the potential green network savior with new names like packet-optical transport platform (POTP).
An MSPP allows network element vendors and, consequently, their customers to reduce the overall size of the equipment needed to perform specific functions by combining these functions into a single element. The POTP, for example, combines DWDM, transport, TDM switching, and packet switching in a single platform, which reduces the need for separate switches, routers, ROADMs, and transport elements. Vendors thus can demonstrate energy savings versus the traditional method of operations and enable network providers to reduce the total power required per bit-per-second in their networks.
Other green innovations from the equipment vendors include advanced power management schemes that, for example, put end-user equipment into a “sleep mode” when not in use. FTTH equipment sold to major carriers worldwide are now required to “sleep” during hours that voice, video, and data are not actively delivered to the customer. The sleep-mode requirement includes a fast restart so that the end user does not experience a noticeable lag when picking up the phone or turning on the television. This sleep option not only reduces the energy consumed by the end device (energy that the service provider rarely pays for), but also extends battery life and increases component lifetimes.
Component vendor challenges and opportunities
Green requirements eventually filter down to the component vendors, who are asked to make lower-power components with more functionality, higher speeds, increased complexity, higher reliability, and smaller sizes—all at the same price points as previous component generations. Some of these issues can only be solved via fundamental research, but other concepts have also been employed.
A “green” approach that has recently moved from the research phase to mass acceptance and deployment is alternative modulation schemes for optical transmission. In the past, higher-speed transmission meant faster on/off-keyed equipment, resulting in increasingly more powerful equipment, more complex network designs, and more ancillary network components (chromatic dispersion compensators, gain tilt compensators, polarization-mode dispersion compensators, etc.). At 40 Gbps, however, the industry has accepted a move to amplitude and phase modulation schemes (generically referred to as APSK, or amplitude and phase-shift keying; see Figure 2) that reduce network complexity by lowering the effective symbol rate of the signal. Further innovations at 100 Gbps such as dual polarization will continue to allow networks designed for much lower speeds to support tremendous amounts of traffic without any expensive and green-unfriendly upgrades.
Figure 2. As speeds have increased, modulation formats have moved from on/off keying to schemes that combine amplitude and phase shift keying (APSK). Developers currently have focused on dual polarization (DP) combined with APSK for 100-Gbps requirements.
Research continues at the most fundamental levels of telecommunications. At the chip and board level, research into optical chip-to-chip and board-to-board signal transmission is nearly ready to break through to the mainstream, with silicon photonics research such as IBM’s Terawave project and the innovations proposed by startup companies like INSiAVA and Kotura promising revolutions in power consumption and signal speed.
Photonic integrated circuit (PIC) innovators like Infinera and Luxtera, meanwhile, are producing the ever smaller emitters, modulators, and detectors required for advanced transmission systems, resulting in lower-power devices that operate at ever higher speeds.
System-on-chip innovations continue to put more functionality into smaller and lower power packages as well. Further research into low-power designs for high-speed circuitry is just starting to emerge from the laboratories and will make an impact in the next three to five years.
For component vendors and researchers, the challenges are significant, but there are also great opportunities. For the first time in many years, significant research is required to meet customer requirements, which means that the industry is ripe for another wave of innovative products, technologies, and perhaps even a new startup company or two.
Opportunities throughout the supply chain
Green initiatives are creating opportunities at all layers of the supply chain. At the systems level, the new requirements for green networks indicate a willingness among carriers to discuss new equipment, new designs, and perhaps new vendors outside of the traditional incumbents. Power reduction and other green initiatives are showing up as requirements in formal RFPs from both large and small carriers. Equipment vendors who are able to develop new concepts for power, maintenance, and network complexity reduction have a new opportunity to make an impact.
The bottom line of the green imperative in telecommunications is cost savings, which is not necessarily a new concept. What is new is the industry’s collective agreement on a common path to such savings that is given the same priority as capacity expansion and feature innovation. And when the industry agrees on a common path, there are always opportunities for innovative vendors, researchers, and entrepreneurs.
Scott Wilkinson is vice president of product management and system engineering at Hitachi Communication Technologies America Inc.