NSN White paper October 2013
Nokia Solutions and Networks Active Antenna Systems: A step-change in base station site performance
CONTENTS
Executive Summary
3
Active Antennas for exibility Beamforming increases capacity
4 5
Ecient utilization of active antenna systems Carrier-specic tilting System-specic tilting Multi-Operator Network Sharing Intelligent Beamforming with SON Lower overall site costs Improved network availability Higher energy eciency and RF performance
6 6 6 6 7 7 7 7
NSN Flexi Multiradio Antenna System
8
Conclusion
10
Abbreviations
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Executive Summary Active Antennas oer an innovative way to address capacity, coverage and space requirements in the macro layer to cope with the rapidly increasing use of data typical in smartphone-dominated networks. Active antennas are characterized by radio frequency (RF) components integrated directly to the antenna radiating elements, which results in high power eciency with zero cable attenuation. This is unlike conventional passive antenna systems connected to separate RF modules by cables that attenuate the signal and power. As well as reducing the number of elements required on a mast or pole, RF component integration enables electronic software-based beam shaping and steering in various dimensions.
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Active Antennas for exibility In order to reduce cable and power losses, conventional base station systems have evolved towards Remote Radio Heads (RRHs) typically located close to the antenna with lighter and shorter RF cables. The latest RRH development is the Integrated Antenna System or IAS, also known as Antenna Integrated Radio (AIR), in which a separate RF unit is housed physically inside the antenna casing, making the solution more compact. Passive and static in nature, the IAS lacks the beam steering and beam forming features of Active Antennas. The Active Antenna System integrates several RF components (power ampliers and transceivers) directly to the antenna radiating elements, and enables precise electronic individual phase and amplitude control using signal processing to shape and steer radiated beam patterns vertically and horizontally. This oers signicant coverage and capacity gains compared to the conventional static beams of passive antennas. Smaller in size, the active antenna oers more practical and environmentally friendly deployments for crowded urban hot spots that often have limited and costly space, and where new sites are dicult - if not impossible - to nd. Active antennas are also more ecient due to their lack of RF cables, which increases the actual output power, making them even more attractive to operators. Eight Integrated RF components
Vertical beamforming (cell splitting)
TRX TRX
Two independent cell sectors from the same antenna radome increases coverage and capacity
TRX TRX TRX TRX TRX TRX Common
Fiber to baseband unit
DC power
Fig. 1: Integrated RF components enable intelligent beam forming, which boosts base station eciency
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Beam forming increases capacity One main advantage of active antennas is their ability to create and steer beams within one cell. Beam forming is achieved by constructive and destructive interference propagation control to alter the phase and relative amplitude of the emitted signal from each active radiating element. While constructive interference amplies the radiated beam in a given direction, destructive interference is used to precisely steer the beam. With vertical beamforming one sector can be split into multiple cells, each with its own dedicated resources, which improves overall sector performance, even more so at the cell edge. By deploying vertical sectorization and optimized inner/outer sector tilt separation, gains of up to 70% in the downlink and as much as 160% in the uplink have been measured in eld trials and simulations under high load situations. Nokia Solutions and Networks (NSN) active antennas deploy Intelligent Beamforming (IBF) that adapts to changing trac patterns automatically according to real-time network trac data feedback.
f 1 i n n e r
Digital beam steering
f1
f2
Carrier-specic tilting
f 1 o u t e r
Cell splitting (vertical)
Separate Tx/Rx tilting
O p .1 O p . 2
Operator-specic tilting
L T E
W C D M A
Technology-specic tilting
Receiver Diversity
SON
Enabled
Fig. 2: Active antennas oer a wide range of beamforming options to cater for varying trac patterns across macro sectors
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Ecient utilization of active antenna systems Carrier-specic tilting Carrier-specic tilting controls multiple carriers individually to address various trac demand scenarios. For example, an operator can tune each of several carriers independently to optimize capacity or peak rates to achieve the best combination of coverage and mobility. System-specic tilting System-specic tilting controls the tilt of dierent radio technologies using the same frequency. It can be used to achieve better individual control of interference and other performance characteristics of dierent radio technologies. Multi-Operator Network Sharing Network sharing is a growing trend aimed at reducing costs by sharing network infrastructure in a similar way to system-specic tilting; an active antenna system can be used to manage transmission power between operators sharing an antenna. Operator-specic bandwidth can be tilted and resources allocated independently to meet the needs of each according to subscriber density or some other factor. For example, one operator could be allocated 20W of an active antenna power, while the other would need 40W. Assymmetric tilt per carrier with separate feature and performance focus
Assymmetric carriers and power setting
Frequency
AAS Cell 1 (outer): - 1 to 2 carriers 20W + 20W
}
f4 f3 f2 f1
Inner Cell Focus on high performance
E.g. DC-HSDPA +MIMO = 84 M
}
Coverage layers
Outer Cell Focus on mobility and coverage
Cell 1 (inner): - 1 to 4 carriers 10W + 10W + 10W + 10W
Fig. 3: Carrier-specic tilting for optimizing coverage, mobility and capacity
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Intelligent Beamforming with SON Beamforming can be made intelligent through automation, such as deploying Self-Organizing Networks (SON) algorithms. With SON, dynamic beam steering enables capacity to be distributed where and when needed. SON automates the adjustment and optimization of active antenna parameters according to actual trac mix, location and user behavior based on real-time trac measurements. Lower overall site costs Integrating RF components with the antenna oers major operational cost savings. Without the need for Mast Head Ampliers (MHA) and Remote Electrical Tilt (RET) equipment, active antenna systems have fewer external components, making them faster, easier and simpler to install. Improved network availability With integrated RF components, active antennas feature greater inherent redundancy than conventional antennas, as the failure of one or more transceivers will not disrupt services. Even multiple transceiver failures can be tolerated, maintaining network availability. In the NSN active antenna solution, built-in intelligence detects any failure and automatically adjusts the beam pattern to achieve the best possible performance with the remaining available power and RF resources. This ‘soft-recovery’ feature helps reduce operational costs by reducing emergency service call-outs and by enabling a more exible maintenance program to be deployed. A faulty module can be replaced on-site without removing the entire antenna itself. Higher energy eciency and RF performance The integration of the RF component in the antenna leads to less coaxial cabling and fewer tower top components such as feeders and connectors. Increased power eciency also translates to lower carbon emissions for greener and environmentally healthier operation.
NSN Active Antenna Solution
Active antenna
Comparable solution needing two Remote Radio Heads RRH + feeder + antenna RRH + feeder + antenna
Baseband
Baseband
Fig. 4: Less hardware and easier installation reduce overall site costs compared to conventional integrated antenna systems Page 7
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NSN Flexi Multiradio Antenna System NSN has pioneered Active Antenna Systems and publicly demonstrated successful pilots of the technology since it was introduced in 2008. The NSN Flexi Multiradio Antenna System increases site capacity and coverage with several advanced features such as verticalbeam forming, higher order MIMO schemes and independent Tx and Rx tilting per frequency or Radio Access Technology (RAT). Substantial capacity and coverage increases can be achieved with vertical beam forming. Furthermore, when enabled with industry-leading NSN SON functionality, the customer experience and service quality is greatly improved. Intelligent Beam Forming (IBF) enables active trac optimization based on real-time network measurements, to address changing end-user behavior during the day in a “liquid” manner. High reliability and smart redundancy is achieved with swappable RF units and self-healing features. Future NSN active antenna development is focused on multiple columns and 3D beam forming, to further enhance capacity and address changing needs. The NSN Flexi Multiradio Antenna System is designed to t an existing site solution. Seamless integration drives down costs and speeds up rollout.
Fig. 5: The NSN Flexi Multiradio Antenna System
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• Power Amplier for each radiator element inside the antenna • Optimized design with 8 transmitters/8 receivers with 8 x 10W power ampliers • High output power, up to 2 x 40W for macro deployments. • Flexible power conguration per carrier (1 carrier at 80W, 2 carriers at 40W, etc) • High cell and carrier capacity, for example up to 4+4 WCDMA cells in one sector • Integrated 2 x 2 MIMO • 4-way Rx diversity
Fig. 6: Key elements of the NSN Multiradio Base Station using Flexi Multiradio Antenna System
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Conclusions Base station technology has undergone substantial development over the last two decades. Reduced size and decreased power consumption together with capacity and coverage gains have contributed to more ecient radio networks running at lower operational costs. Active antenna technology continues this trend The benets of an active antenna includes increased capacity and coverage, better energy eciency, lower wind load and optimized operational costs as new radio technologies arrive and as additional spectrum bands become available. As a result, active antennas help operators to not only reduce site-related costs, but to also more costeectively meet the dynamic demands of their mobile customers. Active antenna systems will bring about a step-change in the evolution of radio networks. As a vital part of the NSN Liquid Radio concept, the NSN Flexi Multiradio Antenna System is leading the way. This new technology helps operators to address unpredictable demand by adapting instantly to changing customer needs, to help create new revenue opportunities by unleashing frozen network capacity into a reservoir of resources that can ow to fulll demand, wherever and whenever broadband is used.
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Abbreviations 3GPP GSM EDGE HSPA IAS LTE MHA MIMO RAN RAT RET RF RRH SON TRX WCDMA
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Third Generation Partnership Project Global System for Mobile communications Enhanced Data rates for GSM Evolution High Speed Packet Access Integrated Antenna System Long Term Evolution Mast Head Amplier Multiple-Input Multiple-Output Radio Access Network Radio Access Technology Remote Electrical Tilt Radio Frequency Remote Radio Head Self Organizing Network Transceiver Wideband Code Division Multiple Access
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Nokia Solutions and Networks
P.O. Box 1 FI-02022 Finland Visiting address: Karaportti 3, ESPOO, Finland Switchboard +358 71 400 4000 Product code C401-00838-WP-201310-1-EN ©2013 Nokia Solutions and Networks. All rights reserved. Public NSN is a trademark of Nokia Solutions and Networks. Nokia is a registered trademark of Nokia Corporation. Other product names mentioned in this document may be trademarks of their respective owners, and they are mentioned for identication purposes only.
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