A portable-device real-time locating system (RTLS) having portable devices and in-room radio-transmitting beacons. To determine which room a portable device is in, beacons broadcast radio transmissions containing motion-status information about recent history of perceived motion in a room as determined from a motion sensor in the beacon. Portable devices calculate received signal strength indications (RSSI) from nearby beacons, motion-in-room status sensed and reported by those beacons, plus their own motion status based on a portable-device-based accelerometer. A series of portable-device steps estimates the room-location of the portable based on a combination of RSSI analysis, and a comparison of portable-device-motion history to the perceived and recorded motion-status in a room. The analysis of portable-device-motion history and motion-in-room status produces a better estimate of room-level location of the portable device than an RSSI estimate can produce alone.