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Energy Efficiency Solution Optimizes Energy Use in Mobile Networks

Anne Larilahti, Nokia Siemens Networks

Introduction:

Most of the energy in a typical mobile network is consumed by the base station site. In response to this, Nokia Siemens Networks focuses on the first phase of its environmentally sustainable business solutions offerings that dramatically improve the energy efficiency of its wireless networks, particularly the base stations and base station sites.

“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 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.

Nokia Siemens Networks has made remarkable achievements in reducing energy consumption throughout its base station portfolio, achieving energy consumption levels of 800W and 500W respectively for typical GSM and WCDMA base stations at 2007. Going forward, the company 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.

A step forward towards this target is the new Nokia Siemens Networks Flexi Multimode Base Station that was launched in the Mobile World Congress, Barcelona in February 2008. This cutting-edge base station is more energy efficient than previous versions of Flexi WCDMA base stations, as 3-sector Flexi WCDMA base station site will now consume on average only 430W.

The four main elements of the solution are:

1. Minimization the number of base station sites
The foundation for an energy-efficient mobile network is a good network design that minimizes the number of base station sites required for coverage and capacity. This increases energy efficiency as well. Intelligent network planning is critical for identifying optimum site locations. 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 optimum positions where conventional base stations cannot be located due to limitations on size and weight. This reduces the required number of base station sites. Small equipment has also the added benefit of less visual impact on the environment.

Planning a network for energy efficiency depends on base station site performance and the capabilities of the site solutions deployed. In the area of base station performance, it is important that radio frequency performance is as high as possible at the transmitter and receiver sides in order to maximize the system value for both uplinks and downlinks. This performance improvement will increase the cell size, which in turn minimizes the number of base station sites required in the network. This design is especially important in rural areas.

Another method to improve energy efficiency on network level is Network sharing. Operators can share a tower or they can lease network capacity from a third-party and share the whole network with 2 or more operators. Operator strategy, regulatory environment etc are key aspects to take into account while deploying these types of solutions. Two operators with one fully shared network can bring savings up to 50 percent.

2. Minimization the need for air conditioning
Traditional base station sites are located indoors, where the typical temperature of 25C is maintained with high energy-consuming air conditioning. By increasing the ambient temperature to up to 40C, energy consumption can be reduced by up to 30 percent in existing base station equipment. Depending on the climate, increasing the site’s temperature could be done by using fresh-air cooling with fans instead of an air conditioner, or by setting the air conditioner temperature to 40C instead of 25C.

3. Use the latest base station and Node-b technology
The industry has made remarkable strides in improving the energy efficiency of base stations. The clear leaders in the field are our Flexi Base Station and Radio Server with radio Heads providing up to 60 percent savings on energy. Due to its small size, Flexi base station is also best in class in material consumption as well as bringing benefits by the ease of implementation, as modules can be hand-carried as opposed to moved by heavy equipment.

4. Deployment of software features that optimize the use of radio access for wireless communications
Nokia Siemens Networks utilizes a wide range of software features to improve base station energy efficiency by balancing consumption according to load. Operators can take advantage of low-traffic periods to reduce energy consumption. For example, at night the traffic of a base station is much lower than in the peak period of daytime traffic. During this low-traffic period, a major part of the base station capacity is unused for many hours. This portion could be set to power save mode, shutting down part of the base station to save energy. An extreme case is to shut down the complete capacity of the base station during low-traffic periods. This is handled seamlessly by Nokia Siemens Networks’ intelligent network management solution, the NetAct Service Quality Manager. By leveraging the latest innovations in its software solutions, Nokia Siemens Network is helping operators reduce costs by lowering the energy consumption of base stations during off-peak hours -- without any impact on service levels for users of the network.

Energy efficiency solutions for existing and new networks

Whether an operator is building new coverage or improving an existing network, the Nokia Siemens Networks Energy Efficiency Solution provides the tools to minimize energy consumption at both the site and network levels. At the top level, the methods could be divided into two categories:

1. Improving energy efficiency at existing base station sites
2. Decreasing the number of base station sites in a new network

Energy efficiency for existing networks

In the case of an existing radio access network, it is assumed the operator already has a live and working network with proper coverage and capacity. In this case, appropriate methods focus on improving the energy efficiency of the base station site. The most significant energy consumption savings could be obtained by:

- Decreasing the amount of air conditioner-based cooling by increasing the indoor base station temperature range up to +40C.
- Using software features to balance the base station energy consumption versus traffic.

Higher energy savings could be obtained if the old base station hardware is replaced with the latest technology while still using the existing site locations.

There are many options that can be used individually or in various combinations to save energy in an existing Base Transceiver Station (BTS) site. For example, one operator may just reduce cooling and use the software features, while another operator may use a new base station site with reduced cooling and the software features.

Energy efficiency for new network

In a case of new radio access network, a broader range of methods can be used to improve energy efficiency. These methods include improving energy efficiency at the base station site and optimizing the number of needed base station sites.

Methods to decrease the number of required base station sites could include use of:
- Best RF sensitivity products in industry without Mast head Amplifier ( Flexi RF Module and RF Head)
- Feederless sites ((either with Flexi Radio Head or Flexi RF Module)
- Use of lower frequencies when available
- Use of four-way receiver diversity

For a new base station site, the following methods can minimize the site-level energy consumption:
- Use of an outdoor base station or indoor base station with reduced cooling
- Use of software features to balance energy consumption versus traffic
- Use of the latest base station equipment

Nokia Siemens Networks target is to improve even more

The telecommunications industry is striving to improve the energy efficiency of its latest-generation base stations. As the leader in wireless communication solutions that connect people and businesses in an environmentally sustainable way, Nokia Siemens Networks has made remarkable achievements in reducing energy consumption throughout its base station portfolio, achieving energy consumption levels of 800W and 500W respectively for typical GSM and WCDMA base stations. Going forward, the company 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.

Nokia Siemens Networks environmental vision

Nokia Siemens Networks places a strong emphasis on an environmentally sustainable business approach that consists of minimizing the environmental impact of its network solutions and services. The goal is to connect the world in a way that creates a net positive impact to the environment by maximizing the benefits telecommunications can bring to people and businesses, while minimizing the environmental footprint of Nokia Siemens Networks products and operations.