Radio networks normally account for around 80% of the total electricity used by an operator, and so the power consumption of each cell site is coming under intense scrutiny – but what solutions are the operators faced with, and what are the benefits to their business of going green?
Modern radio and broadcast technologies such as WCDMA, WiMAX and DVB provide consumers with high bandwidth mobile connectivity 'on the move', but at a cost – high network power consumption due to the poor efficiency of the RF power amplifiers (PAs), which often account for over half the power consumption and heat dissipation of a 3G base station.
High power consumption translates directly to high operator OPEX and a significant environmental impact, both of which are now increasingly unacceptable. The telecommunications industry is striving to improve the energy efficiency of its latest generation base stations, achieving energy consumption levels of 800W and 500W respectively for typical GSM and WCDMA base stations. Going forward, the industry has set even more ambitious targets: to further reduce the energy consumption of its GSM and WCDMA base stations to the 650W and 300W respectively by 2010.
Many operators have plans to remove air conditioning from cell-sites, or are installing more intelligent controls to minimise the power used for cooling. In addition, operators are looking at turning off selected base stations overnight (this needs to be done carefully to avoid coverage and capacity issues), and reducing the amount of equipment on 'hot standby'.
Current 3G base stations are very power-inefficient due to the (necessary) use of linear RF power amplifiers (PAs) – the PA dominates the power consumption of the base station, accounting for approximately half of the total power used, and generating large amounts of heat.
Early base stations were particularly power-hungry, and although later designs are better there is still considerable room for improvement.
The new generation of Node Bs now starting to be deployed have the potential to approximately halve the figures quoted above, but the overall power consumption of 3G radio networks, and their carbon footprint, will remain unacceptably high, and bolder solutions are required.
One solution to the power consumption problem is now becoming available through Nujira, which has developed its HAT Modulator technology. Nujira says this can make a significant contribution to the power efficiency of the Power Amplifier (PA), improving this from the 15% of 'traditional' PAs to 45% and more, together with significant knock-on effects on the overall design of the base station, in many cases allowing cooling fans and air-conditioning systems to be dispensed with, with a consequent improvement in operational and maintenance costs, and equipment reliability.
"Current power amplifier designs for WCDMA, WiMAX and LTE are very inefficient," said Julian Hildersley, VP of Strategy and Marketing at Nujira. "Nujira's High Accuracy Tracking modulator technology, allows power amplifier designers to dramatically improve power amplifier efficiency. Nujira's technology dynamically controls the power supplied to the amplifier ensuring that very little is wasted as heat – an essential requirement for next-generation technologies".
With radio networks normally accounting for around 80% of the total electricity used by an operator, the power consumption of each cell or transmitter site is a critical factor in helping operators meet their critical OPEX and environmental impact targets.
Nujira says that additional benefits arising from the use of the HAT technology include lower maintenance costs and greater reliability through reduced heat dissipation, and lower site installation and CAPEX costs as a result of the reduction in equipment size and footprint, and battery backup, which Nujira's technology allows.
Nujira's technology allows the design of smaller and cheaper base stations and transmitters that better match the increasingly challenging requirements of operators and broadcasters. In addition, the inherently broadband nature of Nujira's technology allows the design of broadband PAs that can be deployed in a flexible manner to support different frequency allocations worldwide, reducing inventory requirements.
One company that has implemented the Nujira solution is Sumitomo Electric Industries (SEI), which is bringing high power, high-efficiency WiMAX and LTE (Long Term Evolution) RF Power Amplifiers to the cellular infrastructure market.
Tim Haynes, CEO of Nujira, says, "Working with a strategic partner such as Sumitomo is very important to Nujira, especially given their strong market presence in Japan, the first country in the world to deploy LTE commercially. Nujira's technology enables infrastructure vendors to reduce the power consumption and size of base stations, reducing both network rollout costs and ongoing energy costs – an increasingly important consideration for operators worldwide."
Yoshikazu Nishiwaki, General Manager of Broadband Equipment Development Department at SEI comments, "SEI is working with Nujira to lead the way in high efficiency amplifier design. By using Nujira's HAT technology, SEI will offer customers industry-leading RF Power Amplifier efficiencies that significantly reduce operating carbon footprint. This collaboration further demonstrates SEI's continued commitment to our customers and the environment."
Under the terms of their agreement, SEI will develop and market high power RF amplifiers targeted at next generation cellular base stations using Nujira's HAT module.
But the large equipment vendors too have got in on the act. Ericsson made a point of its green credentials at the recent Mobile World Congress, and launched a "green" base station design back in 2007. Its commitment extends from materials used in base station build, to the design and efficiency of the base stations themselves. Carl-Henrik Swanberg used Australian operator Telstra, which is a significant Ericsson customer, as an example of a company that has benefited from Ericsson's approach.
Chinese telecom equipment provider Huawei has also launched a green base station solution which it says can help operators save over 60% in their energy consumption.
By adopting advanced power magnifier technologies like DPD and A-Doherty, Huawei says the solution can increase the efficiency of power magnifiers by 45%, effectively reducing the equipment's power consumption. That means each base station can help operators save up to 5700 kilowatt hours of electricity each year, which is equivalent to reducing the carbon dioxide emissions of 1.7 tons of coal.
As the power consumption of the distribution base station can be as low as 500W, it can rely on power supplies like solar power, wind power or methane for power supply. At present, the solution using solar power for power supply has been used in 12 countries in Africa.
Yu Chengdong, president of Huawei's Wireless Product Line, says that Huawei deployed up to 100,000 GSM green base stations across the world in 2007 and helped save about 570 million kilowatt hours of electricity in the year, equaling a reduction of carbon dioxide emissions of burning 139,000 tons of coal. Yu said that the company's solution could help operators better achieve sustainable development.
Also taking strides here is Nokia Siemens Networks, which with ACME Tele Power recently agreed to jointly innovate to offer efficient operation, maintenance and energy management solutions to telecom operators. Using ACME's range of passive infrastructure solutions, the companies will create solutions intended to improve networks' environmental performance and positively impact customers' competitiveness and profitability. The two companies will also establish a joint development lab in India to examine future opportunities, specifically around remote energy monitoring solutions.
"While we have made significant headway in the market with our energy efficiency solutions, we are continually exploring new ways to drive environmental sustainability and reduce costs for our customers. With ACME, we see an opportunity to break new ground with further innovative customer solutions. We are looking forward to working with them in emerging markets where the ability to provide cost effective rural connectivity is key," said Ashish Chowdhary, head of Managed Services, Nokia Siemens Networks.
"We have a good understanding of emerging markets and have devised a wide range of products and solutions that effectively address the cost efficiency and energy management challenges that typically face operators in these markets. Together with Nokia Siemens Networks' leadership in mobile networks, this collaboration is a win-win proposition for operators," says Manoj Upadhyay, Managing Director, Acme Tele Power Ltd.
A significant proportion of total cell site costs can be directly linked to energy especially in emerging markets. Energy savings go straight to the bottom line, with a consequently positive impact on operator financials. ACME's says its products reduce operation costs at cell sites by up to 40% through efficient energy management. It also claims they contribute directly towards reducing green house gas emissions through optimising diesel generator set operations. Customers can therefore contribute positively towards environmental conservation, besides deriving additional benefit from carbon credits.
Nokia Siemens Networks believes that advanced communication technology can play a significant role in creating a sustainable future; in reducing adverse environmental impacts while maintaining opportunities for economic welfare and growth. This was the motive for the company-wide launch of an environmentally sustainable business approach last year which now plays a key role in all of the company's network products and solutions. Nokia Siemens Networks is working on new models of energy management to help customers with OPEX reduction and business transformation.
"The Energy Efficiency solution makes good green business sense," said Ari Lehtoranta, head of the Radio Access business unit at Nokia Siemens Networks. "By bringing state-of the art products and software together with our Services portfolio for operators, we can reduce adverse environmental impact while also generating considerable cost savings for our operator customers."
The four main elements of the solution are: minimizing the number of base station sites; minimising the need for air conditioning to cool the sites; using the latest base station technology; and, deploying software features that optimize the use of radio access for wireless communications. The energy consumption of a base station site can be reduced by up to 70 percent with Nokia Siemens Networks' Energy Efficiency solution. This significant reduction in energy consumption creates a more environmentally friendly network operation and lower operating costs for Nokia Siemens Networks' operator customers.
Building a network with a minimum number of base station sites increases energy efficiency, and intelligent network planning is critical for identifying optimum site locations. The Nokia Siemens Networks Energy Efficiency solution uses software features to increase coverage, thus minimizing the number of required base station sites. The solutions also take advantage of innovative Nokia Siemens Networks planning products to create new types of sites in previously non-viable locations. The Nokia Siemens Networks Flexi Base station, for example, makes it possible for operators to locate complete base stations in places and positions where conventional base stations cannot be located due to limitations on size and weight.
Traditional base station sites are located indoors, where the typical temperature of 25?C is maintained with high energy-consuming air conditioning. By increasing the ambient temperature to up to 40?C, energy consumption can be reduced by up to 30 percent in existing base station equipment.
Nokia Siemens Networks utilises a wide range of software features to improve base station energy efficiency by balancing consumption according to load. For example, because nighttime base-station traffic is much lower than during peak daytime hours, part of the base station can be shut down or its capacity can be set on power save mode at night. This is handled seamlessly by Nokia Siemens Networks' intelligent network management solution, the NetAct Service Quality Manager.