Therefore, the channel emulator needs to have the RF fidelity and scalability to address and test these capabilities. Below is a checklist of key technical specifications and capabilities engineers should look for when selecting a channel emulator for testing devices and networks. Figure 2 illustrates a test case with channel emulation supporting these items.

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• Scalability/multiple channels: up to 4x4 architecture to support spatial multiplexing, space-time coding/maximal ratio combining, and beamforming

• Flexible configuration: including the ability to configure point-to-point and point-to-multipoint, unidirectional, and bidirectional for throughput and handoff-type testing

• Bi-directional: time-division duplex (TDD), frequency-division duplex (FDD), beamforming, etc., require real-world upstream and downstream

• High-RF fidelity: error vector magnitude (EVM), noise floor, and dynamic power range broad enough to not impair testing.

• Channel models: standard and custom user-defined channel models are required to test a variety of scenarios

• Real-time dynamic channel modeling: long model repeat and playback times

• Control and automation: emulation control from the graphical user interface (GUI) and scripts to build test automation.

• Ease of use: Simple setup, configuration, and test execution, as well as results collection to allow independent or integrated testing

Summary

The complexity of broadband wireless technologies like LTE and Mobile WiMAX that employ MIMO and OFDM technologies, combined with the high expectations from the users of newly delivered mobile broadband services, is driving the need for more intensive testing to ensure interoperability and performance in the network. The use of channel emulators to test devices using recreated, real-world channel conditions facilitates much more comprehensive testing.

By providing a broad and cost-effective solution to test whether RF and MIMO algorithms are working properly and predict performance of MIMO-based products in a real-world environment, laboratory-controlled channel emulation can accurately characterize the effect of RF interactions on the conformance, performance, and interoperability of equipment and networks. Only through such comprehensive testing can manufacturers ensure that new, data-intensive applications and devices will successfully work on 4G mobile networks.