Technical White Paper for the Single Antenna Solution 01 · Technical White Paper for the Single Antenna Solution Author Dongqing (56681) Issue V1.0 Date 2012-08-27 HUAWEI TECHNOLOGIES

Technical White Paper for the Single Antenna Solution

Author Dongqing (56681)

Issue V1.0

Date 2012-08-27

HUAWEI TECHNOLOGIES CO., LTD.

Issue V1.0 (2012-08-27) Huawei Proprietary and Confidential

Copyright © Huawei Technologies Co., Ltd.

i

Copyright © Huawei Technologies Co., Ltd. 2012. All rights reserved.

No part of this document may be reproduced or transmitted in any form or by any means without prior

written consent of Huawei Technologies Co., Ltd.

Trademarks and Permissions

and other Huawei trademarks are trademarks of Huawei Technologies Co., Ltd.

All other trademarks and trade names mentioned in this document are the property of their respective

holders.

Notice

The purchased products, services and features are stipulated by the contract made between Huawei and

the customer. All or part of the products, services and features described in this document may not be

within the purchase scope or the usage scope. Unless otherwise specified in the contract, all statements,

information, and recommendations in this document are provided "AS IS" without warranties, guarantees or

representations of any kind, either express or implied.

The information in this document is subject to change without notice. Every effort has been made in the

preparation of this document to ensure accuracy of the contents, but all statements, information, and

recommendations in this document do not constitute a warranty of any kind, express or implied.

Huawei Technologies Co., Ltd.

Address: Huawei Industrial Base

Bantian, Longgang

Shenzhen 518129

People's Republic of China

Website: http://www.huawei.com

Email: [email protected]

http://www.huawei.com/

mailto:[email protected]




ii

Contents

1 Overview of the Single Antenna Solution ............................................................................... 3

2 Challenges Posed by Multi-band and Multi-mode Networks to Antennas ...................... 4

2.1 Trend of Multi-band Coverage ......................................................................................................................... 4

2.2 Limited Tower Installation Space ..................................................................................................................... 4

2.3 High Building Roof Rental Fees ...................................................................................................................... 5

2.4 Increased Wind Load and Tower Reconstruction Due to Increased Antennas ................................................. 5

2.5 Smooth MIMO Evolution ................................................................................................................................ 5

3 Single Antenna Solution ............................................................................................................. 6

3.1 Reducing Antenna Dimensions by Reusing Arrays .......................................................................................... 6

3.2 Using the SBS Platform for Optimal Antenna Dimensions and Performance.................................................. 7

3.3 Lowering the Wind Load by Simulating .......................................................................................................... 8

3.4 Supporting MIMO Evolution ........................................................................................................................... 9

4 Conclusion .................................................................................................................................... 10




3

1 Overview of the Single Antenna Solution

As a node closest to users in radio networks, antennas serve as the last hop to transmit data to

users. With further expansion of the mobile broadband (MBB) network capacity, the MBB

network will adopt more frequency bands and radio network technologies in the future. The

single antenna solution is developed to meet requirements for multi-band and multi-mode

networks and plays an important role in the MBB network evolution.




4

2 Challenges Posed by Multi-band and Multi-mode Networks to Antennas

2.1 Trend of Multi-band Coverage

The MBB network data throughput is expected to witness an annual fourfold increase in the

next five years, and more frequency bands will be used in radio networks to improve system

capacity. The introduction of long term evolution (LTE) requires more new frequency bands,

such as the LTE700, LTE800, LTE1800, LTE2300, and LTE2600. Meanwhile, to meet

requirements for the coexistence between the LTE and the global system for mobile

communication (GSM) and universal mobile telecommunications system (UMTS), each

sector requires multiple frequency bands for coverage, which becomes a trend.

A European operator predicts that the radio network will use 40% more antennas with three or

more bands for coverage in the next 3 to 4 years.

2.2 Limited Tower Installation Space

Additional antennas are required as each sector requires more frequency bands for coverage.

However, solely adding antennas cannot solve all the problems due to limited tower

installation space and tower load, and high building roof rental fees. According to statistics,

more than 18% “one antenna solution” fail to be upgraded to “two antennas solution” in some

European countries, and more than 90% “two antennas solution” cannot be upgraded to three

antennas solution”.




5

2.3 High Building Roof Rental Fees

The rental fees of building roofs in dense urban areas are increasingly high. For example, in

Hong Kong, the rental fee of a building roof for a single antenna tops 4000 Hong Kong

dollars per month.

2.4 Increased Wind Load and Tower Reconstruction Due to Increased Antennas

When the wind load area increases, the tower loading capacity may increase at the same time.

The following figure shows the tower load (in the unit of 1000 kg) required at a wind speed of

40 m/s. The antenna area accounts for 30% of the total tower area, affecting the tower wind

load obviously. New antennas or an improper antenna wind load design increases the

possibility of tower reconstruction. The tower reconstruction costs are extremely high. For

example, the tower reconstruction cost usually reaches 100 thousand Euros per tower in

Europe.

Tower load at the speed of 40 m/s (in the unit of 1000 kg)

Wind pressure area

Height (40 m)

Height (45 m)

Height (50 m)

Height (55 m)

Height (60 m)

Height (65 m)

Height (70 m)

20

15

10

5

0

15 m2

30 m2

2.5 Smooth MIMO Evolution

In addition to adding frequency bands, the multiple-input multiple-output (MIMO) technology

can be used to improve system capacity. However, most operators are not sure of which

frequency band to choose to support MIMO currently. For example, an operator currently uses

the GSM900 and GSM1800. With the LTE, the operator hopes to use the LTE2600 in the

future. However, the operator is not sure whether it can obtain the management right of the

LTE2600. If the operator cannot obtain the LTE2600, the operator can implement LTE

refarming on the GSM1800, which causes uncertainties of LTE frequency bands. In addition,

the operator is not sure about the future service development requirements and the use of

2T4R or 4T4R. Therefore, to meet the requirements for the LTE MIMO evolution, antennas

must be deployed properly for once to flexibly support configuration with various frequency

bands and MIMO.




6

3 Single Antenna Solution

The single antenna solution provides multi-band and ultra-wideband antennas that require less

antennas, smaller dimensions, and lower wind load. This effectively supports upgrade of

frequency bands in the future, avoids repeated antenna installation and tower reconstruction,

and reduces building roof rental fees, meeting requirements for multi-band and multi-mode

networks.

The following figure shows a “one antenna solution” and “two antennas solution”. When the

antenna width increases slightly in the “one antenna solution”, it evolves from supporting dual

frequency bands to supporting five frequency bands and the “two antennas solution” evolves

from supporting three frequency bands to supporting five frequency bands. More frequency

bands are supported without adding antennas, meeting operator's requirements for antenna

reconstruction.

The single antenna solution is developed to tackle the challenges brought by multi-band and

multi-mode networks from the following aspects.

3.1 Reducing Antenna Dimensions by Reusing Arrays

Antenna dimensions, especially the antenna width, are key factors affecting antenna

installation. When the antenna width is larger than 350 mm, antenna installation becomes

difficult or even impossible.

Array reduction directly reduces antenna width. Traditionally, each frequency band adopts an

array for independent electrical tilt. For example, a dual-band antenna requires two arrays.

The width of multi-band antennas greatly increases. Antenna arrays can be used by multiple

frequency bands, and the key is to achieve independent electrical tilt based on different

frequency bands. Currently, filters are the most advanced technology used in the industry to

achieve independent electrical tilt. A filter divides frequency bands of independent electrical

tilt signals that are then transmitted through different frequency bands, enabling array reuse.




7

Antenna band division filters use band elimination filters for band combination. For example,

combine 790–862 MHz and 880–960 MHz to share 790-960 MHz arrays. The design of band

division filters focuses on ensuring high phase consistency, low losses and intermodulation,

and a small size.

After array reuse, antenna width is greatly reduced. The following table lists the width of

antenna with array reuse and width of antenna without array reuse. After array reuse, antenna

width is reduced by more than 40%.

Antenna Type Width of Antenna with Array Reuse

Width of Antenna Without Array Reuse

1800, 2100, 2600 tri-band 323 mm 504 mm

1800, 2100, 2600, 2600 quad-band 323 mm 744 mm

3.2 Using the SBS Platform for Optimal Antenna Dimensions and Performance




8

The use of traditional antenna platforms, especially the Stack platform, and the array reuse

technology reduces width of multi-band antennas. The Side-by-side (SBS) platform is a better

choice for antennas with three bands or above to achieve optimal antenna width and

performance. The following table takes tri-band antennas as an example. When the SBS

platform is used, the antenna width is about 350 mm (within an acceptable range) and the gain

increases by 1 to 2 dBi.

Platform Frequency Band (MHz) Width (mm) Length (mm) Gain (dBi)

SBS 790–960/1710–2690/1710

–2690

Approx. 350 Approx. 2600 15/18/18

Approx. 2000 16/18/18

Approx. 1400 15/17/17

Stack 790–960/1710–2690/1710

–2690

Approx. 290 Approx. 2600 17/17/17

Approx. 2000 16/16/16

Approx. 1400 15/15/15

3.3 Lowering the Wind Load by Simulating

The wind load is a key parameter providing information about a tower and supports for base

station antennas. Wind load simulation helps evaluate and compare the wind resistance factors

for various cross sections in the initial stage of antenna cross section design and finally select

a cross section with a favorable wind resistance factor. Optimize the thickness distribution of

the radome based on the wind load simulation result and structural mechanics result to

minimize the radome weight while ensuring radome stiffness. The following figure shows

main wind load simulation technologies in the industry.




9

CFD

A computational fluid dynamics (CFD) simulation is performed for antenna cross

sections to compare the wind speeds and wind pressures at different cross sections and

optimize antenna cross sections, which helps obtain an optimal wind resistance factor

and reduce the wind load. Increase or decrease the thickness of parts on the radome

based on the wind pressures to improve radome strength and reduce radome weight.

FSI

A fluid-structure interaction (FSI) simulation is performed for an 3D antenna model to

calculate the total wind pressure on the antenna and to radome deformation and add

internal supporting structures for thin areas on the antenna, ensuring proper antennas

stiffness under a heavy wind load.

3.4 Supporting MIMO Evolution

The tri-band antenna shown in the following figure uses two arrays. One high band array is

divided into 1710–2170 MHz and 2490–2690 MHz that share the same array, reducing

antenna dimensions. Meanwhile, the other array provides ultra-wide band (1710–2690 MHz)

for flexible band configuration. With reserved ports and frequency bands, 1800 MHz, 2100

MHz, and 2600 MHz 2T2R, 2T4R, and 4T4R can be flexibly configured, eliminating

operator's concern about uncertainties in MIMO evolution.




10

4 Conclusion

The Single Antenna Solution provides multi-band and ultra-wideband antennas that require

less antennas, smaller dimensions, and lower wind load, and supports MIMO evolution. This

effectively helps operators avoid difficulties in antenna installation and tower reconstruction,

address troubles of new high rental fees, and eliminate uncertainties in MIMO evolution.

The Single Antenna Solution uses array reuse technologies to greatly reduce antenna width,

adopts the SBS platform to obtain optimal antenna dimensions and performance (especially

for antennas with three bands or above), performs wind load simulation to reduce the wind

load, and considers MIMO evolution requirements.

Documents

Technical White Paper for the Single Antenna Solution 01 · Technical White Paper for the Single Antenna Solution Author Dongqing (56681) Issue V1.0 Date 2012-08-27 HUAWEI TECHNOLOGIES