Abstract: The present method provides for a session initiation protocol timing arrangement which facilitates instant communications in a packet data communication system (50). Each network server (15-25) sets a time out timer (92) which is coordinated with each of the downstream network servers. Network server (15), for example, sets a time out timer value which is selectable by the system operator. Subsequent network servers (20 and 25) then set the value of the time out timer to be that of the originating server (15) or client (10) less a fixed time such as one second. Further, a provisional message (118) is sent through the network to avoid expiration of the time out timer in upstream stages.

Abstract: A communication system (100) includes an aircraft (120) that acts as a repeater between ground equipment (101) and communication units (128) on the ground. The ground equipment (101) includes multiple base transceiver stations (104, 106, 108) that provide traffic channels, control channels, and access channels. The channels are all in a single beam (124) projected from aircraft (120). Relative loading on access channels is influenced by access class lists (200, FIG. 2) assigned to control channels. Access classes can be transferred from one list to another, or they can be removed from a list. Relative loading of traffic channels on the base transceiver stations is influenced by assigning different time offsets to base transceiver station so that calls can be transferred from one base transceiver station to another.

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 method manages an internet protocol address and time of validity. The method obtains (52) the IP address and validity time period for a mobile station (10). The IP address and validity time period are transmitted (53) to the mobile station (10). Prior to expiration of the validity time period the network (20) renews the IP address for a new validity time period.

Abstract: A terrestrial cell site handoff list is dynamically maintained for an airborne cellular system. A beam pattern is maintained relative to an airborne cellular system repeater, but rotates relative to the geographic area of coverage. A location and heading of the airplane, locations of respective beams transmitted from the airplane based on airplane flight pattern data, and locations of respective cell sites within a vicinity of footprints of the respective beams transmitted from the airplane are determined. A list of viable handoff terrestrial cell site candidates is then calculated based on the beam pattern, the location and heading of the airplane, the locations of respective beams transmitted from the airplane based on airplane flight pattern data, and the locations of respective cell sites.

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 CDMA cellular communications network (400, FIG. 4) includes one or more aircraft (410), which relay pilot channel and control channel signals between base transceiver stations (BTS's 406, 413) and subscriber units (401). Over the control channel, the BTS transmits a handoff candidate list to the subscriber units. The handoff candidate list identifies candidate BTS's to which the subscriber unit, theoretically, could hand off. In addition, the list indicates at which offsets the subscriber units should search for short codes transmitted by the candidate BTS's over the pilot channel. Based on the path length between the BTS, aircraft, and subscriber unit, the candidate BTS's actually generate their short codes at an offset that is equal to or earlier than the offset reported to the subscriber unit by some delta. In addition, the BTS's can impose a variable delay on the generated short code bits to compensate for variations in the path delay as the aircraft flies in its flight pattern.

Abstract: A method of locating a billing area associated with a cell phone call initiated in an airborne cellular communications system enables service providers to more accurately identify system user locations within the system's area of coverage. In operation, propagation delay and beam number location of an initiated call are identified to determine a current handset radial beam location. The propagation delay is then mapped to a stored closest corresponding radial geographic billing location, and the call is then associated with the closest corresponding radial geographic billing location. Additional system accuracy may be provided by determining azimuthal position within a beam footprint by determining a handoff location of a signal from a first beam to a second beam, and then mapping handoff information to a closest corresponding azimuthal geographic billing location. Both the closest corresponding radial and azimuthal geographic billing locations are then used to identify a current handset location.

Abstract: An aircraft based communication system (10) defining a wireless service area (20) is disclosed. The communication system (10) includes a communication gateway (30) connected to a terrestrial based communication network. A first aircraft (12) is located in proximity to the wireless service area (20). The first aircraft (12) communicates with the gateway (30) and communicates with at least one subscriber (24) located within the wireless service area (20). The first aircraft (12) transmits a first control signal (16) within the wireless service area (20). A second aircraft (14) is located in proximity to the wireless service area (20). The second aircraft (14) being operable for communicating with the gateway (30) and being operable for communicating with the subscriber (24) located within the wireless service area (20).

Abstract: A method of increasing satellite communication quality by using a MEO satellite constellation (12) and a LEO satellite constellation (14) in combination with a decision algorithm which selects the appropriate constellation to route a communication signal through. The decision algorithm can be embodied in three ways: gateway based (18), individual subscriber unit based (22) and satellite based (12, 14). The MEO constellation (12) and LEO (14) constellation may be cross-linked, allowing for switching of service between satellites, as needed, during a communication session.

Abstract: The present invention corrects for Doppler shift in both forward and reverse links in a cellular communications system including an airborne repeater. A reverse link pilot reference signal in a band similar to a communications signal band is received at a reverse link processor, and the Doppler shift in the reverse feeder link is corrected based on the reverse link pilot reference signal. The Doppler shift in the forward feeder link is also corrected based on the reverse link pilot reference signal prior to the forward feeder link being affected by the Doppler shift. The present invention also compensates for signal strength variations due to changing flight pattern positions of the repeater. Pre-compensation for forward feeder link path losses due to movement of the airplane is performed to cause communications signals transmitted to and from the cellular communications system repeater to have identical strength before the signals are transmitted to the system user cell phones within the area of coverage.

Abstract: An airborne repeater antenna array (70) in which beams transmitted from multiple antenna elements (80) of the array to form terrestrial communications. cells are shaped according to predetermined system parameters. At least one of airplane telemetry data (58) indicating an airplane flight pattern location, adjacent cellular system beam footprint data, and call distribution load within a terrestrial cell are received, and a complex gain is dynamically computed for each of the multiple antenna elements based on such data to thereby output a plurality of beams that form desired geographic communications coverage cells (100, 102, 104, 108).

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 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: A cellular communications network (200, FIG. 2) includes one or more aircraft (210), which provide communication channels to cellular communications units, and also communicate with one or more base transceiver stations (206) and a control center (214). The control center receives (502, 602) telemetry and flight parameter information from the aircraft, and calculates (510, 606) network parameters based on the information. The control center transmits (512, 608) messages to the cellular network, including the aircraft, based on the calculated network parameters, and the aircraft and cellular network controls (612) its operations according to information within these messages.

Abstract: Due to the large up front cost in fielding a full capacity satellite constellation (100), it is desirable to have the ability to modify the constellation after deployment to add more capacity in a fashion that does not interrupt service, in order to satisfy a variable or growing market demand. In a satellite constellation including a plurality of orbital planes, each of the orbital planes precesses at a known rate. This invention employs deliberate dynamic manipulation of the orbital precession rates for different satellite planes to increase the separation distance between two adjacent planes. A new plane is then inserted between the two adjacent planes to increase the number of planes and increase the capacity. By continuing a gradual variation, a new orbital plane can be added periodically, e.g. once a year, and the variation can be stopped when no additional orbital planes are desired.

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 multicast message is transmitted from an originating subscriber unit (110, FIG. 1) through a network of satellite communications nodes (120, 130, and 140) to a plurality of receiving subscriber units (150, 160, and 170). Each message is distributed through the network of satellite communications nodes (120, 130, and 140) and replicated at the node nearest to the receiving subscriber unit. Receiving subscriber units (150, 160, and 170) are mapped into geographic cells which allows a single multicast transmission to be transmitted from the satellite communications node to those subscriber units within the same geographic cell. Multicast groups and membership rules are established by the originating subscriber unit (110) through a service provider (180). A multicast session manager (185) manages the multicast session.