A protocol controlled, four level radio communication system for use in a local area such as a hospital, that provides transceivers for fixed users such as patients, transceivers for mobile users such as health care providers, transceiver stations for each area within which a group of fixed and mobile...http://www.google.fr/patents/US5537459?utm_source=gb-gplus-shareBrevet US5537459 - Multilevel cellular communication system for hospitals
Multilevel cellular communication system for hospitals
