Whitepaper
The Importance of Wireless Coexistence Testing for Connected Medical Devices
This Element white paper, written by Connected Technologies Technical Manager David Schaefer, makes the case for rigorous wireless coexistence testing as a distinct and necessary discipline for connected medical devices. Medical devices increasingly rely on a range of radio bands — including MedRadio, MICS, ISM, Medical Body Area Networks, and Wireless Medical Telemetry Service — many of which are shared with military and commercial users, creating real interference risks. The paper draws an important distinction between standard EMC testing and coexistence testing: standard IEC EMC tests contain exclusion bands that eliminate the assessment of in-band interference, meaning they cannot quantify the risk posed by other wireless devices operating on the same frequency. This gap is especially significant in healthcare environments where multiple wireless devices may operate simultaneously for extended periods. The FDA first addressed this in 2007 guidance and now requires coexistence evaluation for virtually all wirelessly-enabled medical devices. The recommended testing approach follows ANSI C63.27, covering co-channel, adjacent channel, and adjacent band interference using representative real-world signals rather than simple noise waveforms. The paper also notes that firmware bugs in Bluetooth and Wi-Fi devices can inadvertently disable cognitive radio and collision avoidance functions, undermining resistance to interference. Looking ahead, the evolving regulatory landscape — including the opening of the 6 GHz band and the growth of 5G — means coexistence testing requirements will continue to expand.