Abstract: The present invention utilizes a dual polarization reception system (200) that utilizes the energy available in orthogonal polarizations to effectively increase link margin, thereby allowing for adequate signal quality reception in difficult environments. A co-polarized and a cross-polarized signal are separately downconverted and demultiplexed. The signals from each demultiplexed output are then sampled and weighted. The weighted samples for each polarity are combined in soft decision combining/decoding circuitry (255, 360), and this circuitry determines the most likely state of a received symbol's transmitted value.

Abstract: A communication system provides multiple wireless services, each potentially having a different information bit rate. A transmitter (400, FIG. 4) encodes (504, FIG. 5) relatively low rate data (430, FIG. 4) using code division multiple access (CDMA). The resulting spread data stream(s) (436, FIG. 4) are multiplexed and modulated (506, 508, FIG. 5) along with relatively high information rate, non-encoded data streams (440, FIG. 4) using a time division multiple access/frequency division multiple access (TDMA/FDMA) protocol. In other embodiments, the methods and apparatus of the present invention can be used in a CDMA only system, or in a system using a time division multiplexing/FDMA and time division multiplexing/CDMA. In one embodiment, the spread data streams are transmitted in timeslots (211-214, FIG. 2) and frequencies (201-204, FIG. 2) that are interspersed between timeslots and frequencies used for the high rate data. A receiver (600, FIG. 6) performs complementary demodulation (704, FIG.

Abstract: A satellite-based communications system (20) includes a communication satellite (22) using a Time Division Duplex (TDD) frame structure. The communication satellite (22) transmits first data (63) during a first sub-frame (150) and receives second data (65) during a second sub-frame (152) of a time division multiple access (TDMA) frame (144). A terrestrial repeater (30) receives the first data (63) using a first link (36) during the first sub-frame (150), delays the first data (63) by a sub-frame duration, and transmits the first data (63) to a subscriber unit (32) using a second link (42). The terrestrial repeater (30) receives the second data (65) from the subscriber unit (32) using the second link (42), delays the second data (65) by the sub-frame duration, and transmits the second data (65) using the first link (36) to the satellite (22) during the second sub-frame (152).

Abstract: A beam control subsystem (200, FIG. 2) provides acquisition, synchronization, and traffic beams (142, FIG. 1) to communication devices (130) within a footprint (144) of a system node (110), where each beam comprises a set of beamlets (140). The subsystem (200, FIG. 2) first acquires (302, FIG. 3) and synchronizes (304, FIG. 3 and FIG. 6) with each communication device. Acquisition involves selecting (402, 416, FIG. 4) and combining (404) sets of beamlets (506, 510, FIG. 5), and determining whether any devices within the sets are attempting to acquire the system. If so, synchronization is performed by varying (604, FIG. 6) beamlet weighting coefficients to find, based on modem feedback, a combination of coefficients that yields a maximum signal-to-interference+noise ratio for multiple users within a beam. The communication device is then handed off (612, 614) to a traffic beam. The subsystem (200) continues, based on modem feedback, to adapt (802, 804, FIG.

Abstract: A time division multiple access (TDMA) communications system (20) includes a first TDMA platform (22) for transmitting a call (32) over a circuit switched communication link (36) to a second TDMA platform (24). The call (32) exhibits a first signal type (84) and second signal type (86). A controller (42) establishes a capacity allocation (200) responsive to the first signal type (84) for the communication link (36). When the call (32) exhibits the first signal type (84), the first TDMA platform (22) transmits first packets (111) of the call (32) in a first packet format (113) using the capacity allocation (200), and when the call (32) exhibits the second signal type (86), the first TDMA platform (22) transmits second packets (140) of the call (32) in a second packet format (139) using the capacity allocation (200).

Abstract: The present invention utilizes a dual polarization reception system (200) that utilizes the energy available in orthogonal polarizations to effectively increase link margin, thereby allowing for adequate signal quality reception in difficult environments. A co-polarized and a cross-polarized signal are separately downconverted and demultiplexed. The signals from each demultiplexed output are then sampled and weighted. The weighted samples for each polarity are combined in soft decision combining/decoding circuitry (255, 360), and this circuitry determines the most likely state of a received symbol's transmitted value.

Abstract: The present invention utilizes a dual polarization reception system (200) that utilizes the energy available in orthogonal polarizations to effectively increase link margin, thereby allowing for adequate signal quality reception in difficult environments. A co-polarized and a cross-polarized signal are separately downconverted and demultiplexed. The signals from each demultiplexed output are then sampled and weighted. The weighted samples for each polarity are combined in soft decision combining/decoding circuitry (255, 360), and this circuitry determines the most likely state of a received symbol's transmitted value.

Abstract: A satellite communication system uses dual satellite coverage techniques to simulate the provision of full duplex communications in the system. Each subscriber (100) in the system communicates with two satellites (102, 104) that use complementary time division duplex (TDD) frame structures (50, 72) for communicating with the subscriber (100). In one embodiment, each satellite in the system performs a transition between a first TDD frame structure (50) and a second TDD frame structure (72) while travelling through a transition region (102) of an associated orbit (130). Preferably, the transition is performed gradually so that an abrupt reduction in system capacity is avoided. In another embodiment, individual orbital planes in the satellite system are dedicated for use with particular TDD frame structures. A subscriber thus communicates with one satellite in each of two planes during a connection.

Abstract: A method and apparatus for soft decision propagation trades off system bandwidth in return for link margin. When signal quality on an uplink is low, a satellite (20) sends soft decision data, rather than hard decision data, to a gateway (40). When path diversity exists on the uplinks, and multiple satellites (20) receive the uplink, multiple versions of soft decision data are sent to the gateway (40). The gateway combines the soft decision data resulting from multiple uplink paths, thereby increasing the effective uplink signal to noise ratio.

Abstract: A method and apparatus are provided for operating a phased-array antenna (14) on a satellite-based communications node (10) in more than one mode by controlling the number of beam-forming elements and by applying appropriate phase-control and/or amplitude-control coefficients to the selected elements. The antenna can be operated as a diffused-beam antenna at a relatively low data rate, enabling the satellite-communications node (10) to communicate with a first terrestrial communications node (22). The antenna can also be operated to generate multiple focused-beam antenna patterns each communicating at a relatively high data rate, enabling the satellite-communications node (10) to communicate with a different terrestrial communications node (20) by changing the amplitude and/or the phase coefficients as well as the number of beam-forming elements.

Abstract: In a code division multiplexed system, a subscriber unit (260, FIG. 1), which includes a pseudonoise code generator (70), is synchronized with the pseudonoise code generator (220) of a communications node (200). Synchronization between the pseudonoise code generators (70, 220) is achieved through measuring the time delay of a signal transmitted from the communications node (200) to the subscriber unit (260) and advancing the code generator of the subscriber unit in accordance with the time delay. This permits transmissions from the subscriber unit (260) to be received synchronously at the satellite. The synchronization is maintained through the periodic transmission from the communications node (200) to the subscriber unit (260) of a message which commands the subscriber unit (260) to adjust the timing of its pseudonoise code generator. The resulting synchronous code division multiplexed system offers increased capacity over conventional systems.