Method of Providing Range Extension Through Data Proxy
Original Publication Date: 2005-Jan-12
Included in the Prior Art Database: 2005-Jan-12
In typical land-mobile wireless communications systems, conventional (non-trunked) subscriber units (SU) typically transmit signals on an uplink frequency that is monitored by a repeater and receive signals on a downlink frequency that is sourced by a repeater. Referring to the communications system 100 shown in Figure 1, vehicles 104, 106, 110, 112, 114 each contain a subscriber unit (SU) and are located within the nominal RF coverage contour of the system. While within the RF coverage contour of the communication system 100, these subscriber units may intercommunicate by way of a repeater 101 using wireless communication links 151, 153, 155, 157, 159. When a subscriber unit roams out of system coverage (e.g., away from the repeater, or into a building), the subscriber unit user typically manually switches to "talkaround" or "direct" mode, whereby the subscriber unit continues to receive signals on the repeater's downlink frequency, but transmits signals on the downlink frequency instead of the uplink frequency. This allows out-of-range subscriber unit users to communicate with nearby users that may or may not be within system coverage. Again referring to the communications system 100 shown in Figure 1, vehicles 108, 116, 118 are geographically located beyond the nominal RF coverage contour of the communication system 100. Additionally, vehicle 102, while located within the outer boundaries of the nominal RF coverage contour, is positioned in an RF "hole" (e.g., an RF "shadow" cast by a large building or a mountain) and is not able to be served directly by repeater 101. When not able to be served by repeater 101, subscriber units 102, 108, 116, 118 may use wireless communication links 161, 163, 165, 167, 169, 171, 173, 175 to communicate with their respective neighboring subscriber units.