Wireless telephone system with diversity transmission and method

Abstract

A wireless communication system combines time and space diversity to reduce fading and simplify receiver design. In particular, a data packet which carries digital telephone traffic, is transmitted at three different times from three different antennas. The mobile subscriber receiver thus receives the same data packet at three different times from three different antennas, and uses the best data packet or combination of the data packets to reduce the effects of fading. A transfer station receives a time division multiplex multiple access (TDMA) signal from a base station carrying telephone data packet traffic to form three data packet repeats at spatially diverse antennas locations. The transfer station further modulates a code division multiple access (CDMA) system using a TDMA signal which links the mobile subscriber receiver to the transfer station. Each data packet received at the transfer station is thus retransmitted at three different times to the mobile subscriber station on a CDMA link. In one embodiment, each transfer station includes the three space diversity antennas. In a second embodiment, three transfer stations, each with one spatially diverse antenna is used. The time division and code division multiplex signals transmitted from space diversity antennas provide the ability to determine subscriber location using the same communication signals which are used for the primary telephone data communication. Specifically, the subscriber station receiver uses the absolute and relative time of arrival of the three repeated data packets to determine the respective distances of the mobile subscriber station to the three transmitting antennas. Since the transmitting antennas are at known fixed locations, receiver location is determined.