Patent ID: 6647244
Filing Date: 2003-11-11
Classification: H04B

Abstract:
A communication system comprising:a base station, a mobile vehicular repeater unit, and a portable unit, said base station transmitting to said mobile vehicular repeater unit over an upper frequency channel portion, and said mobile vehicular repeater unit transmitting to said base station over a lower frequency channel portion and said mobile vehicular repeater unit transmitting to said portable unit over the lower frequency channel portion and said portable unit transmitting to said mobile vehicular repeater unit over the upper frequency channel portion, wherein the following four transmissions occur at different frequencies: transmission from said mobile vehicular repeater unit to said base station; transmission from said mobile vehicular repeater unit to said portable unit; transmission from said base station to said mobile vehicular repeater unit; and transmission from said portable unit to said mobile vehicular repeater; and, wherein: the difference between a frequency at which said mobile vehicular repeater unit transmits to said base station and a frequency at which said mobile vehicular repeater unit transmits to said portable unit is about 2 MHz; the difference between a frequency at which said base station transmits to said mobile vehicular repeater unit and a frequency at which said portable unit transmits to said mobile vehicular repeater unit is about 2 MHz; the difference between a frequency at which said mobile vehicular repeater unit transmits to said base station and a frequency at which said base station transmits to said mobile vehicular repeater unit is about 45 MHz; and the difference between a frequency at which said mobile vehicular repeater unit transmits to said portable unit and a frequency at which said portable unit transmits to said mobile vehicular repeater unit is about 45 MHz.