Qualcomm Incorporated

David S Miller

Leonard N Schiff

Ephraim Zehavi

Judith LaRocca

Nathan Edward Tenny

Ananthanarayanan Chockalingam

Jeffrey A Lorbeck

Avneesh Agrawal

Rajiv Vijayan

Jeffrey Alexander Levin

Nadav Levanon

Sumantra Chakravarty

A satellite communication system for providing communications between user terminals and gateways constituted with m primary satellites. In one embodiment, n back up satellites are also provided. Further, each satellite, primary or back-up, is equipped to project N/m beams onto and across an area in a loosely-packed array manner. M of the m primary and n back-up satellites collectively create N beam spots to cover the area. Moreover, each sub-area is covered by a beam spot separated from another sub-area covered by another beam spot by one beam width. Each satellite is also equipped to facilitate communication over 1 of m band of frequencies on one beam. AS a result, any of the m primary satellites may be efficiently replaced on demand by a selected one of the n back-up satellites. The gateways and user terminals are configured to communicate signals through or with both or either the primary and back-up satellites.

Satellite communication system constituted with primary and back-up multi-beam satellites

A quality measure, such as a signal-to-noise ratio, of a signal arriving at a gateway for a return link is used to adjust a data rate for the link. The return link is transferred from a terminal to the gateway through a satellite, and shared by a number of user terminals at any given time, including the terminal for which the data rate is adjusted. The terminals sharing the link have a certain interference relationship. Adjusting a data rate for a message sent from one or more terminals through the return link in the presence of signal degradation or power loss does not appreciably change the interference relationship among the plurality of terminals.

Noise compensation in satellite communications

A broadband terrestrial message delivery system includes a plurality of wireless communication devices (WCDs), each including a receiver and transmitter, the WCDs capable of not only receiving messages destined for a subscriber associated with a particular WCD, but further capable of acting as a relay point to move messages to and from other subscribers. Message diffusion includes relaying the messages in accordance with all earmark that specifies both the total number of times (N) a message is to be repeated, and the number of times (i) the received message has already been repeated. Methods of improving the spectral efficiency of such a message diffusion architecture include adding a propagation ring width control parameter (J) to the earmark such that a WCD acting in relay mode transmits no more than J repetitions of the message; and providing sectorization such that several sectorized message pathways in a cell may be simultaneously active.

Wireless broadband communications network using message diffusion architecture

Time-scattering of data is employed to reduce the interference effects, such as, error rate, between terminals disposed in nearby beams, or cells, of a communication system. A scattering schedule is determined, typically by a gateway, for a terminal. Scattering instructions, based at least in part on that scattering schedule, are provided to the terminal. The scattering instructions provide terminals with information suitable for controlling the temporal scattering of time slot data to be transmitted by the terminals so that interference impact of nearby out-of-beam terminals is reduced. Time-scattered data received by a receiver remote from the terminal is returned to the desired order by sorting the data in accordance with the scattering schedule to achieve a reversing of the scattering. Time-scattering may be applied to data moving in either or both of the forward and reverse directions of a communication system.

Reducing interference between users in a communications system through time scattering

A variable rate transmission system where a packet of variable rate data is transmitted on a traffic channel if the capacity of the traffic channel is greater than or equal to the data rate of the packet. When the rate of the packet of variable rate data exceeds the capacity of the traffic channel, the packet is transmitted on a traffic channel and at least one overflow channel. Also described is a receiving system for receiving and reassembling the data transmitted on the traffic channel and at least one additional overflow channel.

Method and apparatus for providing variable rate data in a communications system using non-orthogonal overflow channels

A satellite communication system for providing communications between user terminals and gateways constituted with m primary satellites. In one embodiment, n back up satellites are also provided. Further, each satellite, primary or back-up, is equipped to project N/m beams onto and across an area in a loosely-packed array manner. M of the m primary and n back-up satellites collectively create N beam spots to cover the area. Moreover, each sub-area is covered by a beam spot separated from another sub-area covered by another beam spot by one beam width. Each satellite is also equipped to facilitate communication over 1 of m band of frequencies on one beam. As a result, any of the m primary satellites may be efficiently replaced on demand by a selected one of the n back-up satellites. The gateways and user terminals are configured to communicate signals through or with both or either the primary and back-up satellites.

A method for reducing the number of required frequency and time hypotheses to acquire an access transmission in a satellite communication system. By reducing the number of required hypotheses, the amount of hardware required to acquire the access transmission is reduced. The method of the present invention reduces the number of required hypotheses by reducing the range of possible frequency and timing values of the access transmission. The range of possible frequency and timing values is reduced by determining the frequency and time uncertainties over individual satellite beams rather than over an entire satellite footprint.

System and method for resolving frequency and timing uncertainty in access transmissions in a spread spectrum communication system

Apparatus for Doppler correction in a wireless communications system, including a first frequency synthesizer for generating a carrier signal oscillating at a rate responsive to a first input, a counter coupled to the first input for generating a Doppler compensation signal, the counter having a clock input, and a second frequency synthesizer coupled to the clock input for generating a clock signal oscillating at a rate responsive to a rate input. The rate input is adjusted over time according to a predetermined sequence so that the Doppler compensation signal compensates for the Doppler effect experienced by, for example, ground-to-satellite communications in a satellite communications system.

Apparatus for performing doppler correction in a wireless communications system

A handoff technique in which system users detect transitions in service between a current service area and an adjacent service area, and request a forward link channel in the new service area when a detected signal strength for the new service area exceeds predetermined threshold levels. The forward communications link in the current service area is maintained until the strength of the new service area signal reaches a certain level and appropriate channel quality is confirmed, as based on various known criteria. Typically, service area transitions are detected using the signal strength of pilot or paging signals associated with service areas, which are used to determine a relative signal strength of new service area signals. Pilot signal level adjustments used to counter roll-off effects are detected and compensated for in comparing signal levels. To minimize the burden on system resources, new service area signals are not selectable until a minimum time has passed, or a minimum change in energy from a prior pilot signal is detected. In addition, communications using the previous service area can be dropped almost immediately upon engaging the new service area.

Method and apparatus for adjacent service area handoff in communication systems

A new signal processing architecture for base stations and gateways ( ) used in spread spectrum communication systems ( ) that simplifies data transfer, reduces required bus capacity, and does not require special synchronization of signals that are to be combined. A series of transmission modules ( ) are used to transfer data to corresponding ones of a series of analog transmitters ( ) used to form communication circuits for each system user. Each transmission module ( ) employs a series of encoders ( ) and modulators ( ) to form spread communication signals, using appropriate PN spreading codes. Spread spectrum communication signals from each module ( ) for each system user (D), are summed together ( ) and transferred to a single analog transmitter ( ) associated with that module. The signals being combined are automatically synchronized by common timing signals used for elements within each module. The number of processing elements within each module is such that at least one processing path is available for each user or user channel over which it is desired to transmit information through the connected analog transmitter ( ). Data is output from the modules ( ) at a greatly reduced transfer rate which can be more easily accommodated using current technology. This is very useful for satellite based communication systems, or high capacity cellular systems, and this system architecture can be accomplished cost effectively using a series of easily manufactured circuit modules.

Multi-user communication system architecture with distributed transmitters

A system and method for determining a round trip delay of signals transmitted between first and second objects, such as a satellite and a mobile telephone, that move relative to each other. A first signal is transmitted from the first object to the second object. The first signal is received at the second object after a propagation delay D , the delay D being the time taken by the first signal to traverse from the first object to the second object. A frequency of the first signal is measured at the second object. The second object then transmits to the first object a second signal containing a report of the measured first frequency. The second signal is received at the first object after a propagation delay D , D being the time taken by the second signal to traverse from the second object to the first object. The first object measures a frequency of the second signal. The first object then determines the range between the first and second object from the measured overall delay and the measured frequencies of the first and second signals.

System and method for measuring round trip delay on the paging and access channels

A variable rate receiving system where a packet of variable rate data is reassembled on a traffic channel if the capacity of the traffic channel is greater than or equal to the data rate of the packet. When the rate of the packet of variable rate data exceeds the capacity of the traffic channel, the packet is received on a traffic channel and at least one overflow channel. Also described is a transmission system for transmitting the data on the traffic channel and at least one additional overflow channel.

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Auckland, New Zealand

David S Miller