Method and apparatus for providing interactive two-way communications using a single one-way channel in satellite systems

Abstract

A method and apparatus for doubling the capacity of a satellite communication system providing interactive two-way communications with a single one-way communication channel where two parties are utilizing earth stations located within a single satellite beam. Since in voice, facsimile and other types of communications only one user is usually transmitting at a time, a single one-way communication channel can be alternated between two or more users. Multiple users can thus share a single one-way channel since both earth stations are located within a single satellite beam, and therefore are effectively at both ends of the one-way channel.

What is claimed is:  
     
         1 . A method for a satellite system to use a one-way channel to provide interactive two-way communications between communication sites located within a single satellite beam from a satellite, comprising the steps of: 
 assigning the one-way channel to the communication sites;    alternating use of the one-way channel between the communication sites.    
     
     
         2 . The method of    claim 1   , wherein the two-way communications includes transmissions of information signals from a group comprising voice, audio, facsimile, modem, image, video and data.  
     
     
         3 . The method of    claim 2   , wherein said alternating step comprises the steps of: 
 monitoring transmissions on the one-way channel for a silent period;    seizing the one-way channel by a communication site upon detecting said silent period; and    transmitting information from said seizing communication site using the one-way channel.    
     
     
         4 . The method of    claim 3   , further comprising the step of suppressing transmission power at all receiving communication sites.  
     
     
         5 . The method of    claim 4   , wherein each communication site is assigned a low speed subcode to modulate the transmitted information.  
     
     
         6 . The method of    claim 4   , wherein the system uses CDMA.  
     
     
         7 . The method of    claim 6   , wherein the two-way communication is between a first communication site and a second communication site.  
     
     
         8 . The method of    claim 7   , wherein said first and second communication sites use a shared CDMA code to transmit and receive information.  
     
     
         9 . The method of    claim 8   , wherein use of said shared CDMA code is fixed.  
     
     
         10 . The method of    claim 8   , wherein use of said shared CDMA code is desynchronous.  
     
     
         11 . The method of    claim 7   , wherein said first communication site uses a first CDMA code to transmit and receive information, and said second communication site uses a second CDMA code to transmit and receive information.  
     
     
         12 . The method of    claim 7   , wherein said first communication site uses a first CDMA code to transmit information, and a second CDMA code to receive information, and wherein said second communication site uses said second CDMA code to transmit information, and said first CDMA code to receive information.  
     
     
         13 . The method of    claim 1   , wherein there are more than two communication sites using the one-way channel.  
     
     
         14 . The method of    claim 1   , wherein there are more than two users using the one-way channel.  
     
     
         15 . The method of    claim 1   , wherein the satellite system includes at least one satellite from the group comprising geosynchronous earth orbit satellites, mid-earth orbit satellites, low earth orbit satellites, balloon satellites, and airborne platform satellites.  
     
     
         16 . The method of    claim 1   , further comprising the step of suppressing self-echo at a communication site using at least one technique from a group comprising CDMA desynchronization, subtraction, correlation detection and receiver shut-off.  
     
     
         17 . The method of    claim 1   , wherein said alternating step comprises the steps of: 
 receiving a token at a first communication site;    transmitting information from said first communication site using the one-way channel;    passing said token to a second communication site after said first communication site is finished transmitting.    
     
     
         18 . The method of    claim 17   , further comprising the step of suppressing transmission power to said second communication site.  
     
     
         19 . The method of    claim 18   , wherein each communication site is assigned a low speed subcode to modulate the transmitted information.  
     
     
         20 . The method of    claim 18   , wherein said second communication site is prevented from removing said power suppression until said receiving communication site receives said token  
     
     
         21 . The method of    claim 18   , wherein a communication site having transmission power suppressed can remove said power suppression when said receiving communications site has information to transmit.  
     
     
         22 . The method of    claim 4   , wherein a communication site having transmission power suppressed is prevented from removing said power suppression until said receiving communication site detects a silent period.  
     
     
         23 . The method of    claim 4   , wherein a communication site having transmission power suppressed can remove said power suppression when said receiving communications site has information to transmit.  
     
     
         24 . The method of    claim 1   , wherein the system uses at least one medium access method from a group comprising FDMA, TDMA and CDMA.  
     
     
         25 . An apparatus for a satellite system to use a one-way channel to provide interactive two-way communications between communication sites located within a single satellite beam, comprising: 
 means for assigning the one-way channel to the communication sites;    means for alternating use of the one-way channel between the communication sites.    
     
     
         26 . The apparatus of    claim 25   , wherein the two-way communications includes transmissions of information signals from a group comprising voice, audio, facsimile, modem, image, video and data.  
     
     
         27 . The apparatus of    claim 26   , wherein said alternating means comprises: 
 means for monitoring transmissions on the one-way channel for a silent period;    means for seizing the one-way channel by a communication site upon detecting said silent period; and    means for transmitting information from said seizing communication site using the one-way channel.    
     
     
         28 . The apparatus of    claim 27   , further comprising a means for suppressing transmission power to said second communication site.  
     
     
         29 . The apparatus of    claim 28   , wherein each communication site is assigned a low speed subcode to modulate the transmitted information.  
     
     
         30 . The apparatus of    claim 29   , wherein the system uses CDMA.  
     
     
         31 . The apparatus of    claim 30   , wherein the two-way communication is between a first communication site and a second communication site.  
     
     
         32 . The apparatus of    claim 31   , wherein said first and second communication sites use a shared CDMA code to transmit and receive information.  
     
     
         33 . The method of    claim 32   , wherein use of said shared CDMA code is fixed.  
     
     
         34 . The method of    claim 32   , wherein use of said shared CDMA code is desynchronous.  
     
     
         35 . The apparatus of    claim 31   , wherein said first communication site uses a first CDMA code to transmit and receive information, and said second communication site uses a second CDMA code to transmit and receive information.  
     
     
         36 . The apparatus of    claim 31   , wherein said first communication site uses a first CDMA code to transmit information, and a second CDMA code to receive information, and wherein said second communication site uses said second CDMA code to transmit information, and said first CDMA code to receive information.  
     
     
         37 . The apparatus of    claim 25   , wherein there are more than two communication sites using the one-way channel.  
     
     
         38 . The apparatus of    claim 25   , wherein there are more than two users using the one-way channel.  
     
     
         39 . The apparatus of    claim 25   , wherein the satellite system includes at least one satellite from the group comprising geosynchronous earth orbit satellites, mid-earth orbit satellites, low earth orbit satellites, balloon satellites, and airborne platform satellites.  
     
     
         40 . The apparatus of    claim 25   , further comprising a means for suppressing self-echo at a communication site using at least one technique from a group comprising CDMA desynchronization, subtraction, correlation detection and receiver shut-off.  
     
     
         41 . The apparatus of    claim 25   , wherein said means for alternating comprises: 
 means for receiving a token at a first communication site;    means for transmitting information from said first communication site using the one-way channel;    means for passing said token to a second communication site after said first communication site is finished transmitting.    
     
     
         42 . The apparatus of    claim 41   , further comprising means for suppressing transmission power to said second communication site.  
     
     
         43 . The apparatus of    claim 42   , wherein each communication site is assigned a low speed subcode to modulate the transmitted information.  
     
     
         44 . The apparatus of    claim 42   , wherein a communication site having transmission power suppressed is prevented from removing said power suppression until said receiving communication site receives said token.  
     
     
         45 . The apparatus of    claim 42   , wherein a communication site having transmission power suppressed can remove said power suppression when said receiving communications site has information to transmit.  
     
     
         46 . The apparatus of    claim 28   , wherein a communication site having transmission power suppressed is prevented from removing said power suppression until said receiving communication site detects a silent period.  
     
     
         47 . The apparatus of    claim 28   , wherein a communication site having transmission power suppressed can remove said power suppression when said receiving communications site has information to transmit.  
     
     
         48 . The apparatus of    claim 25   , wherein the system uses at least one medium access apparatus from a group comprising FDMA, TDMA and CDMA.  
     
     
         49 . A satellite system using a one-way channel to provide interactive two-way communications between communication sites located within a single satellite beam, comprising: 
 a receiver at a first communication site for receiving a first set of information signals on the one-way channel, said first set of information signals being generated by a first user using a second communication site;    a voice activity detector coupled to said receiver for detecting said first set of information signals, and generating a first detection signal when said first set of information signals are detected, and a second detection signal when said first set of information signals are not detected;    a transmitter for transmitting a second set of information signals to said second communication site on the one-way channel, said second set of information signals being generated by a second user using said first communication site;    a silence power suppressor coupled to said voice activity detector for receiving said detection signal, and coupled to said transmitter for turning power to said transmitter off in response to said first detection signal, and turning power to said transmitter on in response to said second detection signal.    
     
     
         50 . The system of    claim 49   , wherein said second user can turn said transmitter on by generating said second set of information signals.  
     
     
         51 . The system of    claim 49   , further comprising a talkover blocking device coupled to said transmitter for preventing said second user from turning said transmitter on by generating said second set of information signals.  
     
     
         52 . The system of    claim 49   , further comprising a self-echo suppression device coupled to said receiver for canceling a delayed return signal generated by the satellite system when said second set of information signals is transmitted.  
     
     
         53 . A satellite system for providing interactive two-way communications between a first and second earth station, comprising: 
 a one-way channel;    a shared channel device operably coupled to said one-way channel for alternating use of said one-way channel between the first and second earth station.    
     
     
         54 . The satellite system of    claim 53   , wherein each earth station has a transmitter and receiver, and wherein said shared channel device comprises: 
 a voice activity detector operably coupled to the receiver for detecting information signals carried by said one-way channel, and for generating an information detection signal when said information signals are detected; and    a silence power suppressor operably coupled to said voice activity detector for receiving said information detection signal, and suppressing power to the transmitter in response to said information detection signal.    
     
     
         55 . The satellite system of    claim 54   , wherein said shared channel device further comprises a self-echo cancellation device coupled to the receiver for canceling a delayed return signal generated by the transmitter.  
     
     
         56 . The satellite system of    claim 55   , wherein power suppression to the transmitter can be removed by a user of the earth station where power suppression has been implemented.  
     
     
         57 . The shared channel device of    claim 56   , further comprising a talkover blocking device coupled to said transmitter for preventing said user from removing power suppression to the transmitter.  
     
     
         58 . The method of    claim 11   , further comprising the steps of mapping transmissions from said first communication site using said first CDMA code to said second CDMA code for reception by said second communication site, and mapping transmissions from said second communication site using said second CDMA code to said first CDMA code for reception by said first communication site.  
     
     
         59 . The method of    claim 58   , wherein said mapping step comprises the steps of: 
 receiving at the satellite information from said first communication site using said first CDMA code;    decoding said received information;    encoding said decoded information using said second CDMA code; and    transmitting from the satellite said encoded information for reception by said second communication site.    
     
     
         60 . The method of    claim 58   , wherein said mapping step comprises the steps of: 
 receiving at the satellite information from said second communication site using said second CDMA code;    decoding said received information;    encoding said decoded information using said first CDMA code; and    transmitting from the satellite said encoded information for reception by said first communication site.    
     
     
         61 . The apparatus of    claim 35   , further comprising a switch for mapping transmissions from said first communication site using said first CDMA code to said second CDMA code for reception by said second communication site, and mapping transmissions from said second communication site using said second CDMA code to said first CDMA code for reception by said first communication site.