The Opportunities and Challenges of LTE Unlicensed in 5 GHz
David Witkowski, Executive Director, Wireless Communications Initiative
In 1998, the Federal Communications Commission established the Unlicensed National Information Infrastructure or U-NII 5 GHz bands. These are used primarily for Wi-Fi networks in homes, offices, hotels, airports, and other public spaces and also consumer devices. U-NII is also used by wireless Internet Service Providers, linking public safety radio sites, and for monitoring and critical infrastructure such as gas/oil pipelines.

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Band Reject Filter Series
Higher frequency band reject (notch) filters are designed to operate over the frequency range of .01 to 28 GHz. These filters are characterized by having the reverse properties of band pass filters and are offered in multiple topologies. Available in compact sizes.
RLC Electronics

SP6T RF Switch
JSW6-33DR+ is a medium power reflective SP6T RF switch, with reflective short on output ports in the off condition. Made using Silicon-on-Insulator process, it has very high IP3, a built-in CMOS driver and negative voltage generator.

Group Delay Equalized Bandpass Filter
Part number 2903 is a group delayed equalized elliptic type bandpass filter that has a typical 1 dB bandwidth of 94 MHz and a typical 60 dB bandwidth of 171 MHz. Insertion loss is <2 dB and group delay variation from 110 to 170 MHz is <3nsec.
KR Electronics

Absorptive Low Pass Filter
Model AF9350 is a UHF, low pass filter that covers the 10 to 500 MHz band and has an average power rating of 400W CW. It incurs a rejection of 45 dB minimum at the 750 to 3000 MHz band, and power rating of 25W CW from 501 to 5000 MHz.

LTE Band 14 Ceramic Duplexer
This high performance LTE ceramic duplexer was designed and built for use in public safety communication and commercial cellular applications. It operates in Band 14 and offers low insertion loss and high isolation to enable clear communications in the LTE network.
Networks International

See all products in this issue

December 2012

Ian Langley
Director, Aeroflex, Ltd.

Q: The importance of sustaining and developing technology has reached a point where states and cities are more actively building relationships with universities and recruiting high-tech companies. Good examples are New York State’s “East Coast Silicon Valley” and several cities in Ohio. However, there continues to be a shortage of engineering graduates, especially those focusing on RF and microwave technology. What would your company do (or is doing) to help promote careers in microwave engineering?

A: In the past year and a half, Aeroflex Limited, based in Stevenage, UK, made significant contributions to Lancaster University and the University College London to further technical education for RF and microwave engineers. Aeroflex Limited, a wholly owned subsidiary of Aeroflex Holding Corp., focuses on the design, development, and manufacturing of commercial wireless test products.

Aeroflex has a longstanding relationship with both Lancaster University and the University College London, having provided financial support and work placements for postgraduate students. Members of Aeroflex staff regularly contribute to the lecture program, and the company continues to offer placements to students on an ongoing basis.

In 2011, Aeroflex participated in the inauguration of the Aeroflex Wireless Broadband Laboratory at Lancaster University’s School of Computing and Communications at InfoLab21, Lancaster’s world-class center of excellence for research in information and communication technologies.

The new laboratory is equipped with $1.4 million worth of test equipment donated by Aeroflex. The Aeroflex laboratory will enable Lancaster University to play a leading role in the development of the next generation of wireless broadband networks and user equipment, such as smartphones, tablets, and future mobile devices.

In June 2012, Aeroflex Limited helped open the University College London (UCL)-Aeroflex Wireless Communications Laboratory in the Department of Electronic and Electrical Engineering at the university.

Aeroflex equipped this new lab with $2.4 million worth of test equipment. The Aeroflex laboratory will give UCL a major advantage in its research into technology for the next generation of wireless communication networks and user equipment.

The inauguration of this new laboratory affirms Aeroflex’s commitment to supporting academic research, and continues our program of assisting universities who are at the forefront of wireless technology in order to nurture the talented engineers that the industry needs to be competitive in the future.

Q: If your company serves the commercial markets, are you encouraged by any particular emerging application or technology?

A: Aeroflex is continually developing test systems for leading-edge commercial wireless networks. In the past year, we have seen the rise and deployment of wireless devices and networks that demand advanced testing techniques.

LTE, LTE-A, and WLAN 802.11ac are the most prominent in recent months, and will continue to be a main focus for test development throughout 2013. Important test trends and application areas include, but are not limited to:

• Carrier aggregation, which allows multiple carriers to be added together for wider channels and faster data rates

• Increasing performance of HetNets through inter-cell interference cancellation

• Emergence of WLAN and the convergence of cellular and non-cellular devices that must be supported for R&D and manufacturing test applications

• PXI modular architecture continues its ascendance as the flexible, future-proof solution for rapidly changing wireless telecommunications standards

• Support of FDD and key Chinese initiatives

In August 2012, Aeroflex and China Mobile Research Institution (CMRI) signed a Memorandum of Understanding for cooperation covering both LTE and LTE-A. China Mobile is the leading mobile services provider in China, and is the world’s largest mobile network operator in terms of its network size and mobile subscriber base. CDRI, the R&D institute of China Mobile, has spearheaded research into TD-LTE, the TDD version of LTE.

Under the agreement, CMRI and Aeroflex will cooperate on testing technologies for LTE and LTE-A. This includes testing and verification of LTE functionality and performance, as well as key LTE-A technologies such as carrier aggregation, eICIC, and UL-MIMO using Aeroflex’s TM500 Test Mobile and E500 LTE Capacity Test Systems. ZUC is a Chinese-written algorithm that passed the 3GPP plenary meeting in September 2011 and officially became the third encryption algorithm of LTE. By making available the first test mobile on the market to support ZUC for evaluation purposes, we are giving eNodeB vendors and test organizations a head start in this important technology.

In addition, Aeroflex is the first test company to support the ZUC user data security encryption algorithm. In the ZUC test of TDD-LTE Stage II large-scale trial of the Chinese Ministry of Industry and Information Technology, the TM500 LTE Test Mobile tested and verified the first eNodeB base station produced by a Chinese manufacturer.

Measurement Suites for IEEE 802.11ac Devices
Wireless devices using the WLAN IEEE 802.11ac standard will boast 6X increase in network speed over 802.11n. These devices use a less congested part of the RF spectrum, have wider bandwidth, and use more advanced digital modulation techniques.

To facilitate growth in WLAN mobile devices and support terminal testing of devices that combine cellular and non-cellular technologies, Aeroflex added WLAN 802.11ac support to our modular PXI 3000 Series and S-Series RF signal generator and analyzer product lines.

The need for increased device speed, data rates, network capacity, and wide bandwidth have put pressure on the instrument’s hardware to maintain modulation accuracy and increased bandwidth. With the S-Series’ 200 MHz factory-calibrated bandwidth, customers can easily cover the needs of 802.11ac while leaving plenty of room for future technology upgrades.

We believe that a modular architecture-based approach to test systems is undoubtedly the best value for customers. Our modular PXI systems support both transmitter and receiver testing in one compact test system. Silicon vendors, WLAN board integrators, consumer electronics, and contract manufacturers perform critical RF parametric tests on devices during manufacturing. Of key importance to many customers is our non-signaling mode that dramatically reduces test times for manufacturing test applications.

LTE and LTE-Advanced
In commercial wireless markets, Aeroflex is very active in current and future waves of testing for LTE and LTE-A networks that use both the FDD (Frequency Division Duplex) and Time Division Duplex (TDD) standards.

In 2012, Aeroflex launched support for carrier aggregation for FDD and TDD. Carrier aggregation is one of the crucial aspects of the evolution towards LTE-A—it is recognized as presenting a major challenge to the design of user equipment. Carrier aggregation allows multiple carriers comprised of contiguous or non-contiguous spectrum to be added together, allowing wider channel bandwidths and faster data rates to be achieved. For LTE-A, 3GPP Release 10 introduced several new features to augment the existing LTE standard. These features are aimed at raising the peak data rate to 1 Gbps and beyond. Achieving this speed will require a channel bandwidth that is much wider than the 20 MHz currently specified for LTE. This will not be possible with just a single carrier in the limited spectrum bands available to most operators.

Consequently, carrier aggregation will be used to achieve the wider effective bandwidth, typically up to 100 MHz. Our TM500 Test Mobile is the world’s de factor industry standard for testing LTE base stations (eNodeBs). It supports carrier aggregation scenarios and is also ready for all new scenarios currently proposed in the International Telecommunications Union’s 3GPP Release 11. Aeroflex works with leading network infrastructure vendors to enable them to develop and demonstrate a huge LTE data “pipe” that combines the capacity of different frequency bands while maximizing the benefits of the superior propagation capability in the lower frequency band.

The TDD version of LTE and LTE-A is important in China and the rest of Asia, but also in Europe as well, where some TD-LTE networks are already in place. Carrier aggregation is even more pertinent to TDD systems, since it allows small bands of unpaired spectrum to be combined and used efficiently. Providing cellular infrastructure vendors with TDD carrier aggregation at this early stage is vital to testing networks ahead of the availability of real terminals and handsets.

Enhanced Inter-cell Interference Cancellation (eICIC) key to LTE success
Aeroflex supports enhanced inter-cell interference cancellation or eICIC, completing the suite of LTE-A key test features. eICIC is designed to improve the overall performance of heterogeneous network (HetNet) deployments. The main application of eICIC is to improve cell edge performance and coverage in HetNet deployment scenarios where nodes of different types (macro- and picocells) have coverage areas that primarily overlap. HetNets are becoming a reality to address the need for increased network capacity. Self-organizing networks will be an important method for improving heterogeneous network performance and efficiency in an automated way. This brings with it the need for more sophisticated interference management techniques to exploit these benefits, and also the right instruments to verify this performance.

In short, Aeroflex continually tracks and develops test systems for all the latest LTE and LTE-A updates, ensuring that infrastructure vendors can test each capability as soon as it is needed.

Q: Last year, we asked what impact the global economic crisis was having on the markets you serve and on how you run your business. What is your current perspective?

A: We are seeing the greatest potential for growth in North America and Asia where trial LTE networks are going live and commercial networks are starting to roll out. Europe is following a similar pattern. In developing countries, 2G and 3G technologies are still predominant, and we still see ongoing investment in these areas. With our continued R&D investment in core wireless technology, Aeroflex Limited is in a strong position to compete globally in wireless test. ♦


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