A system (10) and method delivers simplex signals (26, 28) to a communication unit (24) located within an area (20) (e.g., a building) where an obstruction exists between the signal transmitter (12, 18) and the communication unit (24). The system (10) uses an infrastructure retransmission...http://www.google.co.uk/patents/US5784028?utm_source=gb-gplus-sharePatent US5784028 - Method and apparatus for simplex delivery of signals to obstructed geographical areas 
