Mobile networks using a mixture of radio sizes could cut energy usage by 50%
The IntelliSpektrum project brought together Bell Labs, the Fraunhofer Institute for Applied Solid State Physics, the Fraunhofer Heinrich-Hertz-Institute and Intel Mobile Communications GmbH. The project demonstrated how, even as mobile data traffic rises, and the number of devices connecting to a network increases, base stations can be dynamically adapted to better manage traffic loads and save energy without any adverse affects to end-user service quality.
Specifically the project found that significant energy savings are possible in ‘heterogeneous’ (HetNet) mobile networks that comprise a mix of radio base stations, including Macro, Metro, Pico and Femto. Energy savings of over 50% were seen in mobile networks with a high number of small cells compared to those comprised only of macro base stations.
HetNets are able to make more efficient use of infrastructure because they can better adapt to high- and low-load traffic situations.
While the number of radio base stations in close proximity within today’s ultra-broadband networks can create a risk of Inter-cell interference (ICI) and degrade service quality, when interference coordination is employed it not only reduces the risk of ICI but also shows gains in energy and performance — throughput gains of 10% in downlink (when the base station connects to the mobile device) and more than 50% in uplink (when the mobile device connects to the base station) were seen.
Marcus Weldon, President of Bell Labs & CTO Alcatel-Lucent said: “The IntelliSpektrum research project is a perfect example of how Alcatel-Lucent and Bell Labs are collaborating with other industry leaders to innovate. We are committed to research and development of energy-efficient products and technologies that offer improved network performance. Findings from the project underscore the critical importance of small cells and prove that that by deploying a mix of base station radios operators will see better energy efficiency and increased network performance — thereby improving their customers’ experience and increasing efficiency.”
The IntelliSpektrum research project was funded through the German Federal Ministry of Economic Affairs and Energy. The ministry´s “IT2Green” program is targeted to develop technology to enable intelligent spectrum management and deliver energy-efficient and service-optimized access to flexible, hierarchical mobile networks. The project concluded officially in September 2014 when the results were shared during a public workshop.
As part of the project Bell Labs worked on a flexible dualband amplifier module, covering frequency band I (2.1 GHz) and band 7 (2.6 GHz) for the base station transmitter. For the final amplifier stage, different dualband capable GaN based amplifiers were developed, such as Class-ABJ (FhG-IAF Freiburg).
The base station receiver module used a GaN based wideband low noise amplifier (FhG-IAF Freiburg), combined with triband filter solutions, supporting frequency band I (1900 MHz), band 5 (800MHz) and Band 7 (2500 MHz)
A neural network based amplifier linearization approach to different amplifier characteristics was developed. The linearization was applied to the Class-ABJ (IAF) amplifier investigating the potential to improve linearity and energy efficiency.
Management and control software was designed to dynamically adapt the base station to the network situation. It was demonstrated by controlling the flexible transceiver and adapting it to simulated scenarios.
The Fraunhofer Institute for Applied Solid State Physics (F-IAF) worked on the base station transmitter, a high power-efficiency and flexible final stage power amplifier (PA) module was designed using a novel dual-band Class-ABJ concept. The dual-band Class-ABJ PA module delivers high efficiency of up to 60% and output power up to 30 W while maintaining high linearity and gain of over 10 dB in the targeted frequency band I (UMTS – 2100 MHz) and frequency band 7 (LTE – 2600 MHz). Various PA designs and modules have been developed using GaN technology.
For the base station receiver, a linear and broadband packaged MMIC LNA with very high gain of over 30 dB and low noise figure NF of under 1 dB for the wide frequency band 0.4-3 GHz was designed. Various MMIC LNA concepts, again in AlGaN/GaN technology, were implemented, packaged and characterized.
The Fraunhofer Heinrich-Hertz-Institute published a reference implementation of the channel model QuaDRiGa under Lesser GNU Public License.
Intel Mobile Communications developed technology to monitor the cellular modem power consumption state in terminals together with context information on network environment, terminal state and application context.
Intel also provided prototypes of integrated current monitor circuits. These circuits allow observation of the actual current drain of critical cellular modem functional building blocks. The accuracy of the monitoring technology allows the terminals to have faster reactions to network transitions. The monitors can be enabled/disabled on demand and their granularity can be adapted to provide lightweight and scalable solutions required for competitive cellular devices.
