Weighted random selection of transmission resources based on device position

A communication method for transmitting via a satellite from a communication terminal to a base station code division multiple access (CDMA)-spread transmission data, comprising:

• receiving a forward link signal transmitted from the base station via the satellite;
• selecting randomly a spreading code channel for CDMA spreading of transmission data generated upon receiving the forward link signal that includes disaster service initiation information;
• selecting randomly a time slot channel for transmitting the CDMA-spread transmission data;
• selecting randomly a frequency channel for transmitting the CDMA-spread transmission data;
• and
• transmitting to the base station via the satellite as a return link signal the CDMA-spread transmission data in the selected spreading code channel, using the selected time slot channel, at a frequency corresponding to the selected frequency channel;
• wherein
• the selecting randomly the time slot channel comprises;
• when the communication terminal is within a predetermined region, compared with the communication terminal being outside the predetermined region, randomly selecting a relatively early time slot channel, from among time slot channels within a selectable range, and/or
• when the communication terminal is outside the predetermined region, compared with the communication terminal being within the predetermined region, randomly selecting a relatively late time slot channel, from among the time slot channels within the selectable range.

A communication terminal that transmits code division multiple access (CDMA)-spread transmission data to a base station via a satellite, comprising;

• a receiver that receives a forward link signal transmitted from the base station via the satellite;
• a CDMA spreader that CDMA spreads transmission data generated upon the receiver receiving the forward link signal that includes disaster service initiation information;
• a controller that generates a spreading code to be used by the CDMA spreader for CDMA spreading;
• a time division multiple access (TDMA) processor that delays transmission of the transmission data CDMA spread by the CDMA spreader according to a transmitting time slot;
• a frequency division multiple access (FDMA) processor that performs a frequency conversion on the transmission data delayed by the TDMA processor;
• a transmitter that transmits to the base station via the satellite as a return link signal the transmission data frequency-converted by the FDMA processor;
• and
• a global positioning system (GPS) receiver that acquires GPS information,
• wherein the controller commands random selection of a spreading code channel used by the controller, commands random selection of a time slot channel which is a basis of a time for delaying the transmission of the transmission data by the TDMA processor, and commands random selection of a frequency channel for the frequency conversion of the FDMA processor, and
• wherein when a position of the communication terminal obtained from positional information including in the GPS information is within a predetermined region, compared with the position being outside the predetermined region, the controller increases a probability of selecting, from relatively early time slot channels, the time slot which is the basis of the time for delaying the transmission of the transmission data by the TDMA processor;
• and/or
• when the position is outside the predetermined region, compared with the position being within the predetermined region, the controller decreases the probability of selecting, from the relatively early time slot channels, the time slot which is the basis of the time for delaying the transmission of the transmission data by the TDMA processor.

A communication terminal that transmits code division multiple access (CDMA)-spread transmission data to a base station via a satellite, comprising:

• a receiver that receives a forward link signal transmitted from the base station via the satellite;
• a CDMA spreader that CDMA spreads transmission data generated upon the receiver receiving the forward link signal that includes disaster service initiation information;
• a controller that generates a spreading code to be used by the CDMA spreader for CDMA spreading;
• a time division multiple access (TDMA) processor that delays transmission of the transmission data CDMA spread by the CDMA spreader according to a transmitting time slot;
• a frequency division multiple access (FDMA) processor that performs a frequency conversion on the transmission data delayed by the TDMA processor;
• a transmitter that transmits to the base station via the satellite as a return link signal the transmission data frequency-converted by the FDMA processor;
• and
• a global positioning system (GPS) receiver that acquires GPS information,
• wherein the controller commands random selection of a spreading code channel used by the controller, commands random selection of a time slot channel which is a basis of a time for delaying the transmission of the transmission data by the TDMA processor, and commands random selection of a frequency channel for the frequency conversion of the FDMA processor, and
• wherein when a position of the communication terminal obtained from-positional information included in the GPS information is within a predetermined region, compared with the position being outside the predetermined region, the controller selects randomly, from relatively early time slot channels within a selectable range, a time slot which is the basis of the time for delaying the transmission of the transmission data by the TDMA processor;
• and/or
• when the position is outside the predetermined region, compared with the position being within the predetermined region, the controller randomly selects, from relatively late time slot channels within a selectable range, a time slot which is the basis of the time for delaying the transmission of the transmission data by the TDMA processor.

A communication system that communicates between a base station and a plurality of communication terminals via a satellite, wherein

• the base station transmits a forward link signal to the plurality of communication terminals;
• and
• each of the plurality of communication terminals comprises:
• a receiver that receives the forward link signal;
• a transmitter that code division multiple access (CDMA) spreads transmission data generated upon the receiver receiving the forward link signal that includes disaster service initiation information, delaying transmission of the CDMA-spread transmission data according to a transmitting time slot, performing a frequency conversion of the delayed transmission data, and transmitting the frequency-converted transmission data to the base station via the satellite as a return link signal;
• a global positioning system (GPS) receiver that acquires GPS information obtained from the satellite or a GPS satellite;
• and
• a controller that generates, according to a spreading code start timing synchronized among the plurality of communication terminals, a spreading code generated from time information obtained from the GPS information to be used for CDMA spreading by the transmitter, that commands random selection of a spreading code channel used by the controller, that commands random selection of a time slot channel which is a basis of a time for delaying the transmission of the transmission data by the transmitter, and that commands random selection of a frequency channel for the frequency conversion by the transmitter,
• wherein the receiver acquires information of a predetermined region from the received forward link signal;
• and
• wherein when the communication terminal is within the predetermined region, compared with the communication terminal being outside the predetermined region, the controller increases a probability of selecting, from relatively early time slot channels, a time slot which is the basis of the time for delaying the transmission of the transmission data by the transmitter;
• and/or
• when the communication terminal is outside the predetermined region, compared with the communication terminal being within the predetermined region, the controller decreases the probability of selecting, from the relatively early time slot channels, the time slot which is the basis of the time for delaying the transmission of the transmission data by the transmitter.

A communication system that communicates between a base station and a plurality of communication terminals via a satellite, wherein

• the base station transmits a forward link signal to the plurality of communication terminals;
• and
• each of the plurality of communication terminals comprises:
• a receiver that receives the forward link signal;
• a transmitter that code division multiple access (CDMA) spreads transmission data generated upon the receiver receiving the forward link signal that includes disaster service initiation information, delays transmission of the CDMA-spread transmission data according to a transmitting time slot, performs a frequency conversion of the delayed transmission data, and transmits the frequency-converted transmission data to the base station via the satellite as a return link signal;
• a global positioning system (GPS) receiver that acquires GPS information obtained from the satellite or a GPS satellite;
• a controller that generates, according to a spreading code start timing synchronized among the plurality of communication terminals, a spreading code generated from time information obtained from the GPS information to be used for CDMA spreading by the transmitter, that commands random selection of a spreading code channel used by the controller, that commands random selection of a time slot channel which is used as a basis of a time for delaying the transmission of the transmission data by the transmitter, and that commands random selection of a frequency channel for the frequency conversion by the transmitter,
• wherein the receiver acquires information of a predetermined region from the received forward link signal;
• and
• wherein when the communication terminal is within the predetermined region, compared with the communication terminal being outside the predetermined region, the controller selects randomly, from relatively early time slot channels within a selectable range, a time slot which is the basis of the time for delaying the transmission of the transmission data by the transmitter;
• and/or
• when the communication terminal is outside the predetermined region, compared with the communication terminal being within the predetermined region, the controller selects randomly, from relatively late time slot channels within a selectable range, a time slot which is the basis of the time for delaying the transmission of the transmission data by the transmitter.