Abstract: A diversity scheme for allowing a transmitter/receiver, such as a mobile unit in a mobile telecommunications system, to exchange communication signals with more than one control station, such as a base station or satellite. According to an exemplary embodiment of the diversity scheme, the mobile unit scans for the control channel of a second satellite during idle time slots while communicating with a first satellite during active time slots. Once the mobile unit detects a control channel from a second satellite, the mobile unit stores synchronization information and establishes a communication link with the second satellite if shadowing or other severe fading causes signal quality over a communication link established with a first satellite to fall below a threshold level. The diversity scheme also allows the mobile unit to communicate simultaneously with two satellites, using alternate TDMA frames.

Abstract: A message, e.g., a control message, a short message, a voice message or a data message, is transmitted on at least one of a first communications channel having a first redundancy level or a second communications channel having a second, higher redundancy level. A radio communications signal is received on one of the first communications channel and the second communications channel. The received radio communications signal is demodulated to recover the message using a first demodulation scheme if the radio communications signal is received on the first communications channel and using a second demodulation scheme if the radio communications signal is received on the second communications channel. According to an aspect of the invention, the received radio communications signal is coherently demodulated if the radio communications signal is received over the first communications channel and non-coherently demodulated if the radio communications signal is received over the second communications channel.

Abstract: In a wireless communications system, information is communicated over one of a first communications channel having a first redundancy level or a second communications channel having a second redundancy level based on a determination of communications quality for at least one of the channels. In embodiments of the present invention, communications occur over a first channel, e.g., a “standard” channel until a measure of communications quality for that channel, such as bit error rate or frame error rate, meets a predetermined criterion. When the communications quality meets the predetermined criterion, communications shifts to a “robust” high-penetration channel that utilizes substantially the same amount of spectral resource as the first channel but provides significantly increased redundancy. In other embodiments, a terminal, e.g.

Abstract: Exemplary embodiments of the present invention describe terminal position location methods and systems. Relative powers of nearby spot beams which are generated by array antennas are determined. For example, powers from six neighboring spot beams relative to a center spot beam within which a mobile station is currently operating, can be measured relative to the power of the center spot beam. Using information from these measurements, the mobile stations position can be determined using, for example, an exponential model of the spot beam pattern.

Abstract: A diversity scheme for allowing a transmitter/receiver, such as a mobile unit in a mobile telecommunications system, to exchange communication signals with more than one control station, such as a base station or satellite. According to an exemplary embodiment of the diversity scheme, the mobile unit scans for the control channel of a second satellite during idle time slots while communicating with a first satellite during active time slots. Once the mobile unit detects a control channel from a second satellite, the mobile unit stores synchronization information and establishes a communication link with the second satellite if shadowing or other severe fading causes signal quality over a communication link established with a first satellite to fall below a threshold level. The diversity scheme also allows the mobile unit to communicate simultaneously with two satellites, using alternate TDMA frames.