Making the Case for Using Computer Simulations to Gauge Spectrum Interference
As demand for spectrum for commercial use continues to grow, policymakers are exploring spectrum sharing as a way to expand capacity while still fulfilling the needs of federal agencies. This model can work only if rules are designed to maximize the value of spectrum resources without compromising the quality and reliability of telecommunications.
To minimize the probability of interference, spectrum managers separate systems in distance and frequency. The amount of separation is determined by interference protection criteria (IPC), which can be estimated through analysis, measurement, or computer simulation.
Although the analytic method is fast it can also be highly inaccurate. Accurate and repeatable measurements may also be difficult to obtain. One reason is that IPC measurements are often hindered by restrictions on equipment availability. In some cases, spectrum managers need estimates for systems that have not been built yet, so measurements are not possible. In other cases, the systems can only be tested for a brief period of time to avoid service interruptions.
To overcome the limitations of measurement, NTIA’s Office of Spectrum Management and Institute for Telecommunication Sciences (ITS) have made significant investments in computer simulation capabilities. This has provided a tool to use when measurements are not possible, especially when trying to assess a multitude of spectrum sharing scenarios. ITS is NTIA’s spectrum engineering laboratory.