Hardware in the Loop

Using hardware in the simulation loop can greatly increase the simulation speed, especially for Monte Carlo simulations. This concept can be extended to a network of simulation nodes such that the simulation load can be distributed among these nodes for optimum performance. The use of hardware in the simulation loop also supports hardware design in that hardware can be tested using simulation inputs, and the hardware outputs can drive downstream components, whether these downstream components be realized in hardware, in software, or in a combination of hardware and software. The use of hardware in the loop is especially valuable for the development of software radios.

An example of hardware in the loop is provided by the Software Communications Architecture (SCA). Using the SCA approach, it is possible to break up a MATLAB simulation into individual computational blocks. These blocks, now connected by the SCA core framework, can be swapped out with embedded modules implemented in platforms such as DSP or FPGA. By systematically swapping MATLAB blocks with embedded modules, a final configuration can be achieved that matches a functional JTRS deployment. This final configuration can then be used to create an embedded application if desired. To achieve this final configuration, the SCA communications structure needs to be changed into a custom architecture tailored to the platform. This approach is shown in Figure 3.

Figure 3 – Integration of MATLAB and embedded development using the SCA.

Beyond aiding in the design process, this approach can also aid in the testing of completed hardware.  Using the process shown in Figure 3, it is possible to swap the RF front-end of a system with a computational system that simulates the channel in a variety of conditions.  This approach can test the system implementation in a controlled environment with well-known attributes.