The MITRE Tactical Channel Emulation System

We present a robust solution to the problem of predicting and evaluating the performance of fielded tactical radios. The MITRE Tactical Channel Emulation System (TCES) enables the evaluation of networked radios in a laboratory environment using digital baseband emulation of RF propagation conditions. The digital emulation approach offers significant advantages (e.g., cost, logistics, repeatability, etc.) over field testing. Furthermore, digital emulation is preferable to a purely software-based simulation approach in that it offers a high degree of accuracy and precision in radio behavior and can operate in real time. This approach also offers improvements in fidelity and scale over existing analog-based radio testing systems. With the TCES, a scenario encompassing multiple radios that are either stationary or are placed on some arbitrary combination of mobile platforms in a chosen geographical area can be readily constructed using an appropriate front-end modeling tool. The propagation information (e.g., time-varying and position-dependent path loss and carrier phase rotation) is extracted from the front-end tool and is used to control a matrix of Field-Programmable Gate Array- (FPGA-) based digital baseband channels. Each radio transmitter output is captured in real time, converted to a digital baseband signal, and passed through a digital baseband channel. The signal for each radio receiver is comprised of a linear combination of these digital baseband channel outputs. Each linear combination of channel outputs is converted to an analog RF signal and forms the input signal for a given radio receiver. An initial 16-by-16 node prototype of the system has already been used successfully by a DoD customer, and a 32-by-32 node prototype is currently under construction. We present an overview of the system, describe its implementation, and discuss future extensions, such as increasing scale to 64-by-64 and beyond, along with enhancements such as Doppler and multipath c- annels.