Probability of Interference between LP-LDC and LBT MICS Implants in a Medical Care Facility

Abstract

The latest generation of medical implants incorporate RF telemetry to facilitate communication of patient data to the patient's physician. Regulatory agencies have enabled medical implant telemetry by allocating RF spectrum in the 402-405 MHz band. The first generation of regulations mandated the use of a Listen-Before-Talk (LBT) protocol. Most of these regulators, recognizing the need for expanded services, are modifying the regulations to allow a Low-Power Low-Duty-Cycle (LP-LDC) protocol as an alternative access method. Medical implant device manufacturers incorporate mitigation techniques to maintain communication in the face of expected link impairments. Designers must understand the expected operational environment and probability of interference in order to incorporate appropriate levels of such mitigation techniques. In this study the authors use the SEAMCAT-3 modeling tool to examine the probability of interference between LP-LDC and LBT medical implants in a medical care facility, where a high density of implants using either protocol can be expected. This study shows that because LP-LDC transmitters operate with very low power and low duty cycle, they can safely coexist with LBT devices, with extremely low probability of interference. Furthermore, with appropriate mitigation techniques, the probability of any harmful interference is virtually non-existent.