Emulator Takes LTE Testing Into The Real World

Emulator Takes LTE Testing Into The Real World

As a key feature of Long Term Evolution (LTE), multiple input multiple output (MIMO) introduces complex radio conditions that may be helped by emulators and other testing solutions.

Performance testing of multiple-input, multiple-output (MIMO) mobile devices must be conducted under realistic, repeatable, and controllable radio-channel conditions to ensure accurate results. To aid its efforts in this regard, Taiwan’s National Chaio Tung University (NCTU)—an institution with a dedicated fourth-generation (4G) Long Term Evolution (LTE) Broadband Mobile Lab—has chosen wireless test-equipment company Anite to provide the Propsim radio channel emulator. That emulator, which is used with Anite’s MIMO Over-the-Air (OTA) testing system, enables NCTU to simultaneously test all of the portions of a time-division LTE (TD-LTE) mobile device that have a direct influence on end-user experience (i.e., antennas, RF front end, and baseband processing).

Within a laboratory, the emulators simulate real-world radio channel conditions that are critical to MIMO and multiple-radio communications-systems performance. Radio channel parameters include path loss, multipath fading, delay spread, Doppler spread, polarization, correlation, and spatial parameters. In OTA performance testing, a wireless device under test (DUT) is tested in an anechoic chamber, without any cables connected to the DUT. Because of this, true performance testing of an entire radio design is possible. The lack of cable connections eliminates any interference while negating the need to modify designs for testing purposes.

Paul Beaver, Anite’s Product Director, hopes that the Propsim emulator will help to accelerate the development of TD-LTE-capable mobile devices.

The enhanced mobile capacity of a MIMO radio partially depends on antenna design. OTA testing is considered an optimal way of verifying MIMO antenna performance. The Anite OTA solution includes a Propsim channel emulator (FS8, F32, or F8) with MIMO OTA application, a test transmitter, and an anechoic chamber equipped with OTA antennas. The OTA performance testing system with Propsim is scalable from a single cluster to full three-dimensional (3D) platform. As a result, the location and number of test antennas in the anechoic chamber can be altered.

Technical Challenge

For IEEE 802.11ac device manufacturers, a key challenge is implementing wideband MIMO radios in high-volume commercial products. The IEEE 802.11ac standard allows throughput as high as 500 Mb/s per spatial stream and 1 Gb/s overall. Anite claims that its Propsim channel emulator enables the user to design and verify IEEE 802.11n and 802.11ac product spatial multiplexing, beamforming, and MU-MIMO algorithms—as well as the Channel State Information functionality—in shorter time and with enhanced coverage compared to other test approaches.

Commenting on the decision by NCTU to use Anite equipment, Paul Beaver, Anite’s Product Director, says, “We are delighted to see leading laboratories such as NCTU carry out true MIMO OTA testing of TD-LTE devices through the use of our Propsim channel emulators. TD-LTE device manufacturers in Taiwan can now perform pre-testing domestically, which will greatly help to speed up development of new TD-LTE capable mobile devices.”

In a similar move, Anite has been chosen by CanvasM Technologies Ltd., a subsidiary of US test laboratory Tech Mahindra. Anite will provide second-generation (2G), third-generation (3G), and LTE Conformance and Interoperability test solutions for CanvasM Technologies’ new test laboratory in New Jersey. That laboratory was established to respond to growing customer demand for testing services as mobile operators escalate LTE implementations and manufacturers intensify the development of LTE-capable devices.

To shore up its offerings, Anite also has signed an agreement with Finnish company Elektrobit Corp. (EB), whereby EB will sell its test tools business to Anite. This transaction involves the sale of the shares of EB’s subsidiary, Elektrobit System Test, and other related assets in the USA and China. EB’s Test Tools product business provides radio-channel emulation tools and testing solutions for the development of the wireless technologies.

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