Motorola Corporation

James P Redden

David Terris

Keith Andrew Olds

Michael William Krutz

Daniel Richard Tayloe

Kenneth Lee Sowles

Christopher N Kurby

Peter J Armbruster

Shawn Wesley Hogberg

Gerald Joseph Davieau

Bradley Robert Schaefer

William Robert Worger

Steven Paul Sawyer

Richard Lawrence Astrom

A narrowband communication system provides wideband data services in a secondary service band. This limits the impact on primary services in peak traffic regions in that the primary service band is not required to download wideband data from a communication node (e.g., a satellite) to a mobile terminal. The narrowband communication system implements a handoff protocol ( ) that rate negotiates a channel bandwidth of an active connection ( ) to the amount of channels that are available in a new cell. The narrowband communication system preempts ( ) lower priority subscribers when a higher priority ( ) high-speed data terminal requires access to the system and a requested channel assignment is not available ( ). The complexity of a high-speed data terminal communication chipset is reduced by a receiver design that minimizes the range of frequencies that are required to be demodulated.

Channel management technique for asymmetric data services

A plurality of orbiting satellites ( ), each comprised of an onboard computer ( ). Each of the orbiting satellites and a plurality of ground-based computers ( ) are utilized to perform delay-insensitive functions associated with the orbiting satellites. An ubiquitous data link ( ) is maintained between each satellite and one or more of the ground-based computers. The integrated system is configured to allow a satellite to generate a remote procedure call (RPC), transmit the RPC to a ground-based computer, whereupon the ground-based computer processes the RPC and transmits a response back to the satellite. Delay-sensitive tasks and functions are performed by the computer onboard the satellite; delay-insensitive tasks are advantageously performed by the ground-based computer assets.

Methods and apparatus for using ground based processing resources to support orbiting satellites

A communication system is established for providing dual-coverage areas using communication satellites, one or more terrestrial stations and one or more dual-coverage subscriber units (DCSU). The communication system determines when and where to establish dual-coverage areas. Dual-coverage areas are provided using separate beams from two or more satellites. The satellites can be located in a variety of orbits around the earth. DCSUs receive signals and process data from at least two satellites at one time. DCSUs can also transmit signals to at least two satellites at one time. Data packets which are missing from one channel are replaced by data packets on another channel. Path delays are compensated for on the transmit side to minimize processing requirements on the receive side.

Method and apparatus for reducing signal blocking in a satellite

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.

Communication system and method for single channel hand-offs

A subscriber unit (26) contains location data that expires after predetermined time periods that are based on the subscriber's mobility. When the location data has not expired, the subscriber unit requests access (108) to a satellite communication system (10) by providing location data within an access request message. The communication system performs a quick check (214) to validate the location data. Accordingly, time-consuming geo-location procedures are avoided when a call is initiated or being received. When the location data has expired, the subscriber unit requests access (110) without providing location data within the access request message. The communication system performs a complete geolocation procedure (210) to determine valid location data for the subscriber unit. The location data is sent (211) to the subscriber unit and time stamped (113).

Method and apparatus for call establishment in a satellite communication

A method and apparatus for specialized call handling transmits (224) and receives (194) a specialized call request message, determines (196) a location of a remote communication unit (100, 110, 140) sending the specialized call request message, determines (200) at least one service center telephone number which the remote communication unit (100, 110, 140) may use to establish a specialized call, transmits (202, 206) a returned message to the remote communication unit (100, 110, 140) containing a selected service center telephone number, and sets up the specialized call (204, 232) using the selected service center telephone number.

Specialized call routing method and apparatus for a cellular

Handoff methods perform cell-to-cell handoff between cells of the same satellite and between cells of different satellites. Handoff is initiated by an individual subscriber unit (ISU) based on local conditions. Once handoff is needed, the ISU chooses a candidate cell to transfer its communication based on a dynamic handoff candidate list provided by the satellite. After selecting a candidate cell, the ISU requests handoff, the satellite or satellites perform the handoff and communication begins over a new channel in the candidate cell.

Satellite cellular communication methods for performing cell-to-cell

A communication system qualifies access to the services it provides to subscriber units based upon the locations of the subscriber units. Subscriber unit location data are routed through a satellite to a gateway where a home subscriber information manager for the subscriber unit resides. This home gateway selects a service control area and corresponding serving gateway to use in establishing calls to and from the subscriber unit. When an area of uncertainty for the subscriber unit's location overlies a boundary between service control areas, additional location data may be obtained to shrink the area of uncertainty. If the area still overlies a boundary, a serving gateway is selected based upon the current serving gateway, the home gateway, and the service control area where the center of the area of uncertainty resides.

Method and apparatus for qualifying access to communication system

A network includes a system and a population of subscriber units. System satellites move in low earth orbits and form moving cells on the surface of the earth. A pattern of static areas that covers the service area of the system is defined in a map. The system discovers the static areas for the subscriber units. When an incoming call needs to be directed to a subscriber unit, the subscriber unit's static area is converted into identities of beams that form the cells that coincide with the static area. A ring signal is transmitted in only these cells. Subscriber units monitor area identification signals that identify the static areas coincident with the cells where the signals are transmitted. When the static area known by the system is not among the identified static areas, a subscriber unit engages in re-registration communications.

Communication network with incoming calls directed through moving cells

A radio subscriber communication unit maintains an annunciation memory which stores a repertoire of annunciations. When the subscriber unit receives annunciation data messages from a communication network, a particular one of the annunciations is selected and presented to the user of the subscriber unit. An audible segment of the annunciation is passed through a vocoder, amplified, and routed to a speaker for presentation to the user. When annunciations are repeated, a second message may be received to instruct subscriber unit to cease presenting an annunciation.

Subscriber unit which is responsive to annunciation messages

In a satellite cellular communication system, subscriber unit traffic within any cell is managed by changing the signal level of the broadcast channel of the cells. Subscriber units located within the cells monitor the signal levels of the broadcast channels and initiate handoff requests when the signal level of the cell in which the subscriber unit is located falls below the signal level. As demand for communication services within a cell approaches the maximum capacity of the cell, the communication system reduces the signal level of the broadcast channel within the cell encouraging subscriber units within that cell to seek service from other cells. Thus the apparent cell size is reduced as to the subscriber units within the cell.

Method and apparatus for varying apparent cell size in a cellular

A cellular telecommunication system comprised of low-Earth orbiting satellites featuring allocation of communication channels among users in cells is disclosed. Each subscriber unit is programmed with an embedded class identifier. During periods when it is desirable to limit acquisition of a satellite to some restricted class or set of classes, such as periods of heavy use, the satellite broadcasts a list of inhibited class identifiers allowing only uninhibited classes access to the communication system. The method reduces thrashing by allowing access to users on a hierarchy class basis. The method uses both real time cell loading data and historical cell loading information based on previous experiences and can be programmed to limit access to emergency services in the case of natural disasters.

Radio channel access control

Ongoing communications over radio links between communication stations and subscriber units may be unexpectedly broken. Where the communication stations include low-Earth orbit satellites, communication links are difficult to re-establish because of the timing differential and Doppler-frequency shift associated with the satellite's movement. The communication link is re-established by initially changing the modulation technique in an attempt to re-synchronize the communication station and the subscriber unit. If this fails, the subscriber unit performs an acquisition attempt on another antenna beam of the communication station. If this is not successful, the subscriber may perform an acquisition attempt on antenna beams of another communication station.

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Mesa, AZ, United States of America

James P Redden