Abstract: A satellite communications system (10) provides for digital beamforming acquisition. The communications system (10) has an antenna configuration (20) for maintaining communications links with satellite networking equipment, and a signal processing system (30) for processing signals resulting from the communications links. A beamforming subsystem (40) dynamically forms traffic beams and overhead beams, wherein the overhead beams scan overhead areas of the satellite footprint. Overhead areas are defined by areas of the satellite footprint without active traffic channels. The beamforming subsystem (40) includes a channel database configuration (50) containing traffic channel input data and overhead channel input data. A beamforming processor (60) converts the input data contained in the channel database configuration (50) into traffic beams schedules and overhead beam schedules. An antenna management system (70) dynamically forms traffic beams and overhead beams based on the beam schedules.

Abstract: A satellite communications system (10) provides for snap to grid variable beam size digital beamforming. The communications system (10) has an antenna configuration (20) for maintaining communications links with satellite networking equipment, and a signal processing system (30) for processing signals resulting from the communications links. The beamforming subsystem (40) forms beams based on the processed signals wherein the beams match predetermined grid information. The beamforming subsystem (40) includes a grid database (50) containing predetermined grid information. A beamforming processor (60) converts the predetermined grid information contained in the grid database (50) antenna coefficients. An antenna management system forms beams based on the antenna coefficients.

Abstract: A conflict resolution center (130 FIG. 1) is used to manage and resolve resource allocation conflicts in communications system (100) including a number of semi-autonomous communications nodes (SACNs). SACN (110) operates semi-autonomously because SACNs cannot independently allocate and de-allocate resources but rather operate within the confines of at least one local neighborhood. SACNs (110) allocate and de-allocate resources locally based on local neighborhood information. A conflict occurs when at least two SACNs try to allocate the same resource. Conflict resolution center (130) resolves conflicts using a number of different procedures. When a conflict can be resolved, conflict resolution center (130) provides resource reallocation data to at least one SACN (110). When a conflict cannot be resolved, conflict resolution center (130) notifies a system administrator.

Abstract: In a communications system, an earth-based subscriber unit (40, FIG. 1) receives at least one communications beam (50, 60, FIG. 1) transmitted from one or more moving satellite communications nodes (10, 20). The earthbased subscriber unit evaluates which communications beam should be selected based on the power received (FIG. 2, 210), Doppler frequency shift (270), link quality, (290), interference level (300), and satellite and network specific parameters (310). By considering these factors, the earth-based subscriber unit selects the communications beam (50, 60) that will provide the optimum service and reduce the likelihood that an inter-satellite hand over of the call will be required while the call is in progress.

Abstract: A satellite (110 FIG. 1) is used to make channel allocations for SUs (120) in communications system (100). Satellite (110) operate within the confines of at least one subset of satellites. Satellites (110) allocate channels using a maximum cost list that is based on a cost function methodology. A list of potentially interfering antennas is determined using a cost function analysis. A list of active channels on each one the potentially interfering antennas is also established. Another list that includes a set of potentially interfering channels for each active channel is established. Cost functions are computed for each pair of active channels and its potentially interfering channels. These cost functions establish interference potentials for the available channels in the maximum cost list (400). Channels are allocated using the maximum cost list and interference potential thresholds. Cost functions are based on spatial isolation, spectral isolation, and temporal isolation.

Abstract: A channel management process (68) is performed by a parent base station (36) of a radio telecommunications system (20) that exchanges channel usage data with neighbor base stations (38) within its local group (34). When channel usage data indicates a channel assignment conflict, that conflict is resolved in the base station (22) having the lesser loading of the pair of conflicting base stations (22). Channel usage requests received by a base station (22) are prioritized and sequentially processed, channels (58) being assigned for inter-cell handoff requests, then intra-cell handoff requests after inter-cell handoff requests, even when that assignment creates a conflict, and then channels (58) being assigned to new call requests after handoff requests if that assignment does not create a conflict.

Abstract: A method and apparatus for controlling the initiation of new user communication links in a communication system (10), by evaluating the present in-use resources in a particular cell against reserved resources for servicing handoff communications from neighboring cells, evaluating total in-use resources of satellite (12), and determining if present conditions in satellite (12) exceed defined parameters thus inhibiting access by new users. A status is posted and transmitted in a broadcast channel (18) for subscriber units (26) to evaluate prior to initiating requests for communication services.

Abstract: The system (10) and method (100) adjust reuse units when nodes (e.g., satellites (20, 22)) move in a communication system (10), such as satellites (20,22) moving in their orbits around the earth in a space-based communication system (10). The method (100) and system (10) computes interference potentials between a reference reuse unit in a first reuse unit table of a first satellite (20) and reuse units being used in second reuse unit tables in second satellites (20) that are adjacent to the first satellite (20); and when the interference potentials is less than a predetermined threshold, then assigns the satellite a non-interfering reuse unit for the specific time interval.

Abstract: A cellular communication system (10) requests from subscriber units (30) to volunteer for handoff when a call resource shortage is about to occur. The subscriber units (30) may volunteer to handoff to another cell (24) depending on whether any adjacent or neighbor cell (24) provides adequate signal strength for servicing the on-going call. If there is another adjacent or neighbor cell (24) which provides adequate signal strength, the subscriber unit (30) can volunteer for handoff to the other cell. The cellular communication system (10) may accept the volunteer handoff request, whereby the subscriber unit (30) volunteering for handoff is handed-off to the other cell (24). However, the cellular communication system (10) may deny the handoff request. If the handoff request is denied, the subscriber unit (30) may have to drop the call or try to locate another cell to handoff its call before a predetermined amount of time expires.

Abstract: In a satellite communication system (10), a subscriber unit (26) is assigned a communication channel (17). The channel is used in the present cell (54) as well as subsequent cells (54) as the cells move relative to the earth. The channel is assigned using a cost function which includes a distance factor and an isolation factor. The distance factor which is based on a geographic distance between the nearest use of an interfering channel and the subscriber unit's cell. The isolation factor includes an interference potential between two channels. As a result of this channel assignment process, channels become associated with the geographic location of the subscriber unit. Accordingly, subscriber unit communications on the same satellite are handed-off between cells using the same channel making hand-offs invisible to the subscriber unit (26). When a hand-off is needed to another satellite, the same channel may also be used, or a new channel assigned using the cost function.

Abstract: A satellite cellular communication system includes satellites in motion that project cells upon the surface of the Earth. These cells are in motion and pass over individual subscriber units (26) engaged in communications, thus requiring individual subscriber units (26) to perform handoffs as an active current cell (300) currently servicing them advances. Selection of a subsequent servicing cell requires evaluation of active neighboring cells. A pre-computation of candidate cells is performed in advance according to a cell activation schedule. Active neighboring cells of an active current cell (300) are evaluated and prioritized in advance of individual subscriber unit's need for them. A candidate handoff cell list is then delivered to a satellite (12). A candidate handoff cell list is broadcast to all individual subscriber units (26) located within active current cell (300) for use in handoff decisions.