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Environmentally Friendly Wireless Backhaul for WiMAX and LTE
by Erik Boch, CTO & VP of Engineering
2/11/2009
With the current deployment of high bandwidth access networks happening at an ever-increasing pace, the need for efficient, high bandwidth backhaul infrastructure becomes more and more relevant. In fact, the construction of these new access networks depends upon the backhaul network for both technical and financial performance.
Traditional backhaul for legacy [voice] cellular networks was done largely using T1/E1 circuits. These circuits were realized using cabled or wireless tail links to connect the base-station sites to the rest of the network infrastructure.
As bandwidth demands increase, alternatives for backhaul infrastructure become necessary. In today's decision-making environment, traditional business and technology drivers are now also mixed with eco-friendliness in order to optimize the decisions.
So how is it that a backhaul radio system relates to"environmental friendliness"?
Although, many positive environmental impacts are obvious (i.e. reduced power consumption), many of them are not so obvious or secondary in nature. In this latter category, among other things, are factors such as the use of safe and/or recyclable materials, ability/option to use solar (or other) powering and reductions in the consumption of earth minerals, minimization of the disruption of natural habitats during network build-outs.
Broadband Backhaul Implementation Options -- Which is"Greener"?
Generally, there are two basic methods used to provide high bandwidth backhaul connectivity to a given base station site in a mobile network;
1. fiber/cable
2. wireless
Costs of installing fiber/cable have risen steadily due to the escalating costs of;
rights-of-way
zoning permits
public disruption permits
environmental impacts assessments
manual & skilled labor
cost of heavy equipment (which is largely driven be rising fuel costs)
Wireless backhaul deployments, on the other hand, are less dependant on a number of these cost-driving factors and therefore have seen significant declines in deployment costs. The result of this is that overall wireless backhaul deployment costs become somewhat more related to pure capital cost reductions in the associated equipment.
From an eco-friendliness perspective, wireless backhaul deployments are largely unaffected by factors such as environmental impacts and use of heavy machinery. The reduction in environmental impacts and the reduced fuel consumption lend to better overall environmental friendliness.
Wired/Cabled backhaul solutions often involve trenching/digging using heavy machinery. In urban areas, this causes obvious impacts to roadways and traffic (etc). The increased costs and deployment timelines are heavily impacted by zoning, permitting, rights-of-way, public consultations, etc., activities, but incremental environmental impacts are not concerning. On the other hand, rural deployments typically have less zoning, permitting and rights-of-way impairments/costs, but their incremental impacts to the environment are more severe. Increasingly, these impacts are receiving a heightened level of scrutiny … driving up the associated costs and deployment timelines.
Additionally, wired installations require large consumptions of base earth minerals, which are often not mined in an eco-friendly manner or have ecologically stressful post-mining processing associated with them.
Making Wireless Backhaul Even More Environmentally Friendly
Basic wireless backhaul costs and environmental-friendliness can be further improved by understanding other impacting factors and using this information in making good equipment selection choices.
For example, a base station location within a mobile network requires basic electrical power feeds to drive not only the network and wireless equipment, but also HVAC and battery-back-up systems.
Designing backhaul equipment to be low power-consumption and all-outdoors has a significant impact on the site electrical power demands. Aside from needing less battery-back-up infrastructure to maintain a given hold-up performance during power outages, a significant amount of power consumption benefit can be had.
For instance, in comparing an all-outdoor, high-efficiency, low power-consumption wireless backhaul system1 (~ 30W consumption) with a conventional split mount (IDU + ODU) system drawing ~ 100W, it can be seen that there are large overall energy savings2;
1. operating power consumption benefit = ~ $400 per site over 10 years, or $800 per link over 10 years
2. HVAC power consumption reduction benefit = $175 per site over 10 years, or $350 per link over 10 years
The benefit totals ~ $1150/link over 10 years. A large multi-city mobile backhaul network deployment may easily involve thousands or even tens of thousands of links resulting in a cumulatively saving ~ $10M over 10 years in energy costs alone! The key environmental benefit lies of course in the reduction of the amount of hydro carbons produced in the generation of the electricity to start with.
Ultra-low power consumption equipment also enables the possibility of solar [or other "off grid" alternate] powering. Practical installations for solar powering require small solar panel size and therefore low power consumption. Highly integrated, low-part count electronics can be used to achieve a very low overall power consumption level in the radio electronics, thereby enabling it to be "solar-friendly".
Other environmentally-positive aspects of wireless backhaul equipment can take the form of less obvious benefits. For example;
1. use of environmentally friendly materials and processes. These are governed by WEEE3/RoHS4, which defines numerous environmentally unacceptable elements that can be avoided when designing and manufacturing electronic equipment
2. use of WEEE/RoHS compliant assembly processes (i.e. pcb fabrication and CCA fabrication using lead-less solders
3. use of powder-coated painting processes. These processes are largely free of solvents and are highly efficient, as compared to conventional"spray" processes5.
4. outdoor systems with no fans help reduce overall audible noise levels to a minimum.
Hence, there are a number of green attributes that are not apparent when looking at a given product or reviewing its specification sheet.
Summary
Wireless networking technology delivers an interesting and unparalleled solution that not only delivers cost-effectiveness, reduced-time-to-deploy and high performance, yet they also deliver an environmentally-friendly solution whose impact benefit goes well beyond"carbon footprint". Many of these advantages are attained in the product creation processes (i.e. environmentally friendly painting and PCB fabrication) and some even exist after the useful life of the equipment is over (use of RoHS compliant materials).
1 DragonWave Horizon Compact SP product used as an example
2 Assumes 10¢/KW-Hr costs
3 Waste Electrical and Electronic (WEEE) governs environmentally friendly/responsible design and production of electronics (see DIRECTIVE 2002/96/EC OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL)
4 Restriction on Hazardous Substances (RoHS) defines materials that should not be used due to their negative environmental impacts (see also DIRECTIVE 2002/95/EC OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL)
5 Non-water-based spray processes are assumed
About the Author
Erik Boch holds a Masters degree in Electrical Engineering from Carleton University in Ottawa and is a registered professional engineer. Erik has held senior engineering or technical management positions at a number of communications and aerospace companies namely Litton Systems, ComDev, Lockheed Martin and Alcatel Networks (formerly Newbridge). While at Alcatel, Erik was AVP of the Wireless Systems Group and was involved in various aspects of microwave & millimeter wave subsystem and system design for more than 22 years. Erik led the R&D team at Alcatel (formerly Newbridge) that introduced the first ATM-based Fixed Wireless Access System in the industry.
About DragonWave
DragonWave designs, markets and supports broadband, wireless networking products for service providers and enterprises requiring reliable, predictable, interference-free, high-bandwidth transmission of real-time, IP applications. DragonWave products meet the demands of a wide range of applications as well as delivering a value proposition that enables operators and service providers an "invest as you grow" capability that leverages profitable growth. DragonWave is headquartered in Ottawa, Canada's high-technology capital.
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