RF platform for WiMAX channel emulator

WiMAX is opening broader access to high-speed wireless services and is quickly gaining worldwide acceptance. It is also in the midst of a MIMO technology transition to provide ubiquitous high-speed voice, video and data transmission. As WiMAX gains popularity in wide-area wireless network applications, performance verification through rigorous testing of the WiMAX devices under real-world propagation conditions becomes very important. Real-world wireless propagation environment is highly complex and is constantly in a state of change due to many variables, such as devices, environment settings, people, cars, and buildings. Performing repeatable tests in such an environment is impractical. WiMAX channel emulators enable realistic and repeatable wireless tests on WiMAX devices by emulating real world wireless propagation in controlled laboratory conditions. Channel emulation enables vendors and service providers to test WiMAX devices using re-created real-world channel conditions, thus avoiding testing in the "actual" real world and significantly reducing the testing time and expense. The emulator has to interface with real-world devices that transmit and receive radio frequency signals. The interface does this typically by (a) down-converting the RF to a frequency low enough to be conveniently digitized, (b) performing digital signal processing under the control of emulation software residing in a controller (generally a PC) and (c) reconverting the digitally processed signals back to RF. This thesis describes the development of an RF platform that carries out this RF interfacing in the emulator. The RF platform includes frequency down/up conversion, and the IF stage. The unique demands placed on the RF platform are discussed in this thesis and the work done for the development of the RF platform is described. The test results show that the platform developed performs this interfacing function effectively with +/-0.5 dB flatness over 40 MHz bandwidth at each of the WiMAX carriers in 2 to 6 GHz range, while achieving an EVM better than -40 dB over 60 dB dynamic range.