Dual mode satellite/cellular terminal

Claim 2

A dual-mode mobile communications unit comprising: means for communicating voice or data traffic using Time Division Multiple Access (TDMA) signal bursts during allocated timeslots of repetitive TDMA frames, wherein said voice or data traffic is communicated to a land-based network station at a first data rate during a first plurality of timeslots, and wherein said voice or data traffic is communicated to an orbiting relay station at a second data rate during a second plurality of timeslots, with said second plurality of time slots being lower than said first plurality of time slots.

Claim 3

A portable satellite communications terminal using time division multiple access, comprising: TDMA burst receiving means synchronized by synchronizing means to receive and analyze signal bursts received in allocated receive timeslots of a repetitive TDMA frame period and to produce decoded information and a signal quality indication; synchronizing means for synchronizing said TDMA burst receiving means independently for even-numbered and odd-numbered ones of said TDMA frame periods; and TDMA burst transmitting means for coding information and said signal quality indication to produce coded signal bursts for transmission and transmitting coded bursts in allocated transmit timeslots in said repetitive TDMA frame period.

Claim 4

A portable satellite communications terminal using time division multiple access, comprising: TDMA burst receiving means synchronized by synchronizing means to receive and analyze signal bursts received in allocated receive timeslots of a repetitive TDMA frame period and to produce decoded information and a signal quality indication; synchronizing means for synchronizing said TDMA burst receiving means independently for even-numbered and odd-numbered ones of said TDMA frame periods; and TDMA burst transmitting means for coding information and said signal quality indication to produce coded signal bursts for transmission and transmitting coded bursts in allocated transmit timeslots in said repetitive TDMA frame period.

Claim 5

A communications system for providing a communications service to a plurality of first stations with the aid of a network of relay stations each of said relay stations, comprising: coding means for coding data for transmission to said first stations to produce signal bursts; TDMA burst transmission means for relaying said signal bursts to each of said first stations using respective timeslots of a repetitive TDMA frame period such that each of said first stations receives signal bursts in its respective timeslot; detection means for detecting when no data is temporarily required to be sent to one of said first stations; and means controlled by said detection means to transmit signal bursts intended for another of said first stations in the timeslot designated for said one of said first stations temporarily receiving no data as well as transmitting signal bursts in said another station's designated timeslot.

Claim 6

A communications system for providing a communications service to a plurality of first stations with the aid of a network of relay stations each of said relay stations, comprising: coding means for coding data for transmission to said first stations to produce signal bursts; TDMA burst transmission means for relaying said signal bursts to each of said first stations using respective timeslots of a repetitive TDMA frame period such that each of said first stations receives signal bursts in its respective timeslot; detection means for detecting when no data is temporarily required to be sent to one of said first stations; and means controlled by said detection means to transmit signal bursts intended for another of said first stations in the timeslot designated for said one of said first stations temporarily receiving no data as well as transmitting signal bursts in said another station's designated timeslot.

Claim 7

A dual-mode satellite/cellular radio telephone system using a TDMA format, comprising mobile stations, at least a cellular network station and at least a satellite relay station for transmitting TDMA signal bursts including the method of: transmitting bursts in said TDMA format intended for a specific mobile station at a first repetition rate from said cellular network station alternatively at a second repetition rate being a sub-multiple of said first repetition rate from said satellite relay station; dividing bursts transmitted at said first repetition rate into superframe groups each comprising traffic bursts, a Slow Associated Control Channel burst and an idle frame not containing a transmitted information burst; and using said idle frame at said specific mobile station to change its TDMA burst receiver channel frequency to that of a neighboring cellular network station or to the channel frequency of said satellite relay station and performing a signal analysis on the signal received on that channel frequency.

Claim 8

A dual-mode satellite/cellular radio telephone system using a TDMA format, comprising mobile stations, at least a cellular network station and at least a satellite relay station for transmitting TDMA signal bursts including the method of: transmitting bursts in said TDMA format intended for a specific mobile station at a first repetition rate from said cellular network station alternatively at a second repetition rate being a sub-multiple of said first repetition rate from said satellite relay station; dividing bursts transmitted at said first repetition rate into superframe groups each comprising traffic bursts, a Slow Associated Control Channel burst and an idle frame not containing a transmitted information burst; and using said idle frame at said specific mobile station to change its TDMA burst receiver channel frequency to that of a neighboring cellular network station or to the channel frequency of said satellite relay station and performing a signal analysis on the signal received on that channel frequency.

Claim 9

The method according to claim 4, further comprising the step of: reporting from said specific mobile station to said cellular network station the results of said signal analysis.

Claim 10

The method according to claim 4, wherein said method further includes communicating channel frequencies of said neighboring cellular network station and frequencies of said satellite relay station from said cellular network station to said specific mobile station.

Claim 11

The method according to claim 5, wherein said reported signal analysis are used at said network station to determine when said mobile station shall be switched to receive data from a satellite relay station instead of one of said network stations.