Transmit and admission control for cdma satellite communication system

Abstract

A system for performing transmit power and admission control for a satellite based wireless communication systems. Admission control uses centralized admission and distributed admission controls. Centralized admission control uses a maximum persistence value broadcasted from a hub to terminals. Persistence is the probability that a transmission will timely occur. Each terminal transmits a persistence that is no greater than the maximum persistence value. If the transmission fails, the transmission is repeated using the same probability. Lowering the persistence introduces a delay for alleviateing congestion. Power control is performed using centralized and distributed power control. Centralized power control uses power control commands transmitted from the hub to each terminal. When an acknowledge is not received, a backoff and recovery procedure is performed. Distributed power control is performed during the recovery process when a terminal fails to receive an acknowledgment message after a predetermined number of attempts.

I (we) claim: 
     
         1 . A method for operating a terminal in a satellite based wireless communication system that includes a hub comprising the steps of:
 a) transmitting a data message to the hub at a persistence Tx_Per equal to a value Per_Max and with a transmit power Tx_Power set to a first value;   b) adjusting the transmit power Tx_Power by an amount Power_Step if an acknowledgment message containing the amount Power_Step is received from the hub; and   c) performing a failed transmission recovery procedure if the acknowledgment message is not received   
     
     
         2 . The method of  claim 1  wherein step c) is comprised of the steps of:
 c.1) repeatedly transmitting the data message at the transmit power Tx_Power and at the persistence Tx_Per set to less than Per_Max up to a first maximum number of retransmissions R if the acknowledgment message is not received; and 
 c.2) repeatedly transmitting the data message at the persistence Tx_Per set to less than Per_Max and at a transmit power Tx_Power greater than the first value up to a maximum transmit power Power_Max and up to a second maximum number of retransmissions Tx_Max if the acknowledgment message is not received. 
 
     
     
         3 . The method of  claim 2  further comprising the steps of:
 performing a second failed transmission recovery procedure after waiting a random period of time; and 
 entering an initial acquisition mode if the acknowledgment messages not received. 
 
     
     
         4 . The method of  claim 2  wherein step c.1) is comprised of the steps of:
 incrementing a backoff counter i after each transmission; and 
 setting the persistence Tx_Per to set maximum persistence Per_Max divided by the backoff counter I plus 1 raised to a power X after transmission. 
 
     
     
         5 . The method of  claim 2  wherein step c.2) is comprised of the steps of:
 incrementing a backoff counter I after each transmission; and 
 setting the transmit power Tx_Power to Power_Max if less than the Tx_Power plus an amount Power_Up, and otherwise to the Tx_Power plus an amount Power_Up after each transmission. 
 
     
     
         6 . The method of  claim 5  wherein the step of transmitting a data message at a persistence is comprised of the steps of:
 repeatedly generating a random number having a probability of being true equal to the persistence Tx_Per until a true is generated; and 
 transmitting the data message. 
 
     
     
         7 . A terminal in a satellite based wireless communication system that includes a hub comprising:
 a transmitter for transmitting a data message to the hub at a persistence Tx_Per equal to a value Per_Max and with a transmit power Tx_Power set to a first value;   a controller for adjusting the transmit power Tx_Power by an amount Power_Step if an acknowledgment message containing the amount Power_Step is received from the hub; and   the controller for performing a failed transmission recovery procedure if the acknowledgment message is not received.   
     
     
         8 . The terminal of  claim 7  further comprising:
 the transmitter for repeatedly transmitting the data message at the transmit power Tx_Power and at the persistence Tx_Per set to less than Per_Max up to a first maximum number of retransmissions R if the acknowledgment message is not received; and 
 the transmitter for repeatedly transmitting the data message at the persistence Tx_Per set to less than Per_Max and at a transmit power Tx_Power greater than the first value up to a maximum transmit power Power_Max and up to a second maximum number of retransmissions Tx_Max if the acknowledgment message is not received. 
 
     
     
         9 . The terminal of  claim 8  further comprising:
 the controller performing a second failed transmission recovery procedure after waiting a random period of time; and 
 the terminal entering initial acquisition mode if the acknowledgment messages are not received. 
 
     
     
         10 . The terminal of  claim 8  wherein the transmitter for repeatedly transmitting the data message at the transmit power Tx_Power and at the persistence Tx_Per set to less than Per_Max up to a first maximum number of retransmissions R if the acknowledgment message is not received further comprises:
 a backoff counter to increment i after each transmission; and 
 a backoff system to set the persistence Tx_Per to set maximum persistence Per_Max divided by the backoff counter I plus  1  raised to a power X after transmission. 
 
     
     
         11 . The terminal of  claim 8  wherein the transmitter for repeatedly transmitting the data message at the persistence Tx_Per set to less than Per_Max and at a transmit power Tx_Power greater than the first value up to a maximum transmit power Power_Max and up to a second maximum number of retransmissions Tx_Max if the acknowledgment message is not received further comprises:
 a backoff counter to increment I after each transmission; and 
 a backoff system to set the transmit power Tx_Power to Power_Max if less than the Tx_Power plus an amount Power_Up, and otherwise to the Tx_Power plus an amount Power_Up after each transmission. 
 
     
     
         12 . The terminal of  claim 11  wherein the transmitter for transmitting a data message at a persistence comprises:
 a random number generator for repeatedly generating a random number having a probability of being true equal to the persistence Tx_Per until a true is generated; and 
 the transmitter transmitting the data message. 
 
     
     
         13 . A system for operating a terminal in a satellite based wireless communication system that includes a hub comprising the steps of:
 means for transmitting a data message to the hub at a persistence Tx_Per equal to a value Per_Max and with a transmit power Tx_Power set to a first value;   means for adjusting the transmit power Tx_Power by an amount Power_Step if an acknowledgment message containing the amount Power_Step is received from the hub; and   means for performing a failed transmission recovery procedure if the acknowledgment message is not received.   
     
     
         14 . The system of  claim 13  wherein the means for performing further comprises:
 means for repeatedly transmitting the data message at the transmit power Tx_Power and at the persistence Tx_Per set to less than Per_Max up to a first maximum number of retransmissions R if the acknowledgment message is not received; and 
 means for repeatedly transmitting the data message at the persistence Tx_Per set to less than Per_Max and at a transmit power Tx_Power greater than the first value up to a maximum transmit power Power_Max and up to a second maximum number of retransmissions Tx_Max if the acknowledgment message is not received. 
 
     
     
         15 . The system of  claim 14  further comprising:
 means for performing a second failed transmission recovery procedure after waiting a random period of time; and 
 means for entering initial acquisition mode if the acknowledgment messages not received. 
 
     
     
         16 . The system of  claim 14  wherein the means for repeatedly transmitting the data message at the transmit power Tx_Power and at the persistence Tx_Per set to less than Per_Max up to a first maximum number of retransmissions R if the acknowledgment message is not received further comprises:
 means for incrementing a backoff counter i after each transmission; and 
 means for setting the persistence Tx_Per to set maximum persistence Per_Max divided by the backoff counter I plus  1  raised to a power X after transmission. 
 
     
     
         17 . The system of  claim 14  wherein the means for repeatedly transmitting the data message at the persistence Tx_Per set to less than Per_Max and at a transmit power Tx_Power greater than the first value up to a maximum transmit power Power_Max and up to a second maximum number of retransmissions Tx_Max if the acknowledgment message is not received further comprises:
 means for incrementing a backoff counter i after each transmission; and 
 means setting the transmit power Tx_Power to Power_Max if less than the Tx_Power plus an amount Power_Up, and otherwise to the Tx_Power plus an amount Power_Up after each transmission. 
 
     
     
         18 . The system of  claim 17  wherein the means for transmitted a data message at a persistence comprises:
 means for repeatedly generating a random number having a probability of being true equal to said persistence Tx_Per until a true is generated; and 
 means for transmitting said data message. 
 
     
     
         19 . A non-transitory computer-executable storage medium comprising program instructions which are computer-executable to operate a terminal in a satellite based wireless communication system that includes a hub, the storage medium comprising:
 program instructions that cause a transmission of a data message to the hub at a persistence Tx_Per equal to a value Per_Max and with a transmit power Tx_Power set to a first value;   program instructions that cause an adjustment of the transmit power Tx_Power by an amount Power_Step if an acknowledgment message containing the amount Power_Step is received from the hub; and   program instructions that cause a performance of a failed transmission recovery procedure if the acknowledgment message is not received.   
     
     
         20 . The non-transitory computer-executable storage medium of  claim 19  wherein the program instructions that cause a performance of a failed transmission recovery procedure if the acknowledgment message is not received further comprises:
 program instructions that cause repeated transmission the data message at the transmit power Tx_Power and at the persistence Tx_Per set to less than Per_Max up to a first maximum number of retransmissions R if the acknowledgment message is not received; and 
 program instructions that cause repeated transmission of the data message at the persistence Tx_Per set to less than Per_Max and at a transmit power Tx_Power greater than the first value up to a maximum transmit power Power_Max and up to a second maximum number of retransmissions Tx_Max if the acknowledgment message is not received. 
 
     
     
         21 . The non-transitory computer-executable storage medium of  claim 20  further comprising:
 program instructions that cause a performance of a second failed transmission recovery procedure after waiting a random period of time; and 
 program instructions that cause an entrance to an initial acquisition mode if the acknowledgment message is not received. 
 
     
     
         22 . The non-transitory computer-executable storage medium of  claim 20  wherein the program instructions that cause repeated transmission of the data message at the transmit power Tx_Power and at the persistence Tx_Per set to less than Per_Max up to a first maximum number of retransmissions R if the acknowledgment message is not received comprises:
 program instructions that cause a backoff counter to increment i after each transmission; and 
 program instructions that cause the persistence Tx_Per to be set at maximum persistence Per_Max divided by the backoff counter I plus 1 raised to a power X after transmission. 
 
     
     
         23 . The non-transitory computer-executable storage medium of  claim 20  wherein the program instructions that cause repeated transmission of the data message at the persistence Tx_Per set to less than Per_Max and at a transmit power Tx_Power greater than the first value up to a maximum transmit power Power_Max and up to a second maximum number of retransmissions Tx_Max if the acknowledgment message is not received comprises:
 program instructions that cause a backoff counter to increment I after each transmission; and 
 program instructions that cause the transmit power Tx_Power to be set at Power_Max if less than the Tx_Power plus an amount Power_Up, and otherwise to the Tx_Power plus an amount Power_Up after each transmission. 
 
     
     
         24 . The non-transitory computer-executable storage medium of  claim 23  wherein the program instructions that cause a transmission of a data message at a persistence comprises:
 program instructions that cause a repeated generation of a random number having a probability of being true equal to said persistence Tx_Per until a true is generated; and 
 program instructions that cause the data message to be transmitted. 
 
     
     
         25 . A method for operating a wireless telecommunications system having a hub and a terminal that communicate via radio frequency signals relayed from a satellite comprising the steps of:
 transmitting a set of global variables from the hub;   
       transmitting information from said terminal at a transmit power level determined by the global variables; 
       transmitting an acknowledgment message terminal specific power control information from the hub; and
 transmitting information at a second transmit power level determined by the terminal specific power control information. 
 
     
     
         26 . An apparatus for operating a wireless telecommunications system having a hub and a terminal that communicate via radio frequency signals relayed from a satellite comprising:
 a hub transmitter for transmitting a set of global variables from the hub;   a terminal transmitter for transmitting information from said terminal at a transmit power level determined by said global variables;   the hub transmitter for transmitting an acknowledgment message terminal specific power control information from said hub; and   the terminal transmitter for transmitting information at a second transmit power level determined by said terminal specific power control information.   
     
     
         27 . A system for operating a wireless telecommunications system having a hub and a terminal that communicate via radio frequency signals relayed from a satellite comprising:
 means for transmitting a set of global variables from the hub;
 means for transmitting information from said terminal at a transmit power level determined by said global variables; 
 means for transmitting an acknowledgment message terminal specific power control information from said hub; and 
 means for transmitting information at a second transmit power level determined by said terminal specific power control information. 
   
     
     
         28 . A non-transitory computer-executable storage medium comprising program instructions which are computer-executable to operate a wireless telecommunications system having a hub and a terminal that communicate via radio frequency signals relayed from a satellite, the storage medium comprising:
 program instructions that cause a transmission of a set of global variables from the hub;   program instructions that cause a transmission of information from said terminal at a transmit power level determined by said global variables;   program instructions that cause a transmission of an acknowledgment message terminal specific power control information from said hub; and   program instructions that cause a transmission of information at a second transmit power level determined by said terminal specific power control information.   
     
     
         29 . A method for operating a satellite based wireless telecommunication system comprising the steps of:
 a) establishing a communication between a terminal and a hub;   b) repeatedly transmitting messages at a transmit power adjusted in response to acknowledgment messages and overhead transmissions from the hub with a persistence adjusted in response to the overhead transmission; and   c) performing an error recovery procedure when an acknowledgment is not received in response to a message.   
     
     
         30 . The method of  29  wherein step c) is comprised of the steps of:
 incrementing a backoff counter I after each transmission; and
 setting said persistence Tx_Per according to the following equation:
     Tx _Per=Per_Max/( i+ 1)̂ X,  
 
 
 
 wherein, X is a value greater than 1 and less than 2, and Per_Max is a value between 0 and 1. 
 
     
     
         31 . An apparatus for operating a satellite based wireless telecommunication system comprising:
 a terminal and a hub for establishing communication;   the terminal configured to repeatedly transmit messages at a transmit power adjusted in response to acknowledgment messages and overhead transmissions from the hub with a persistence adjusted in response to the overhead transmission; and   the terminal configured to perform an error recovery procedure when an acknowledgment is not received in response to a message.   
     
     
         32 . The apparatus of  claim 31  wherein the terminal configured to perform an error recovery procedure further comprises:
 a backoff counter for incrementing I after each transmission; and 
 setting said persistence Tx_Per according to the following equation:
     Tx _Per=Per_Max/( i+ 1)̂ X,  
 
 
 wherein, X is a value greater than 1 and less than 2, and Per_Max is a value between 0 and 1. 
 
     
     
         33 . A system for operating a satellite based wireless telecommunication system comprising:
 means for establishing a communication between a terminal and a hub;   means for repeatedly transmitting messages at a transmit power adjusted in response to acknowledgment messages and overhead transmissions from the hub with a persistence adjusted in response to the overhead transmission; and   means for performing an error recovery procedure when an acknowledgment is not received in response to a message.   
     
     
         34 . The system of  33  wherein the means for performing an error recovery procedure comprises:
 means for incrementing a backoff counter I after each transmission; and 
 means for setting said persistence Tx_Per according to the following equation:
     Tx _Per=Per_Max/( i+ 1)̂ X,  
 
 
 wherein, X is a value greater than 1 and less than 2, and Per_Max is a value between 0 and 1. 
 
     
     
         35 . A non-transitory computer-executable storage medium comprising program instructions which are computer-executable to operate a wireless telecommunications system for operating a satellite based telecommunication system, the storage medium comprising:
 program instructions that cause an establishment of communication between a terminal and a hub;   program instructions that cause a repeated transmission of messages at a transmit power adjusted in response to acknowledgment messages and overhead transmissions from the hub with a persistence adjusted in response to the overhead transmission; and   program instructions that cause an error recovery procedure when an acknowledgment is not received in response to a message.   
     
     
         36 . The non-transitory computer-executable storage medium of  35  wherein the program instructions that cause an error recovery procedure comprises:
 program instructions that cause a counter to increment I after each transmission; and 
 program instructions that cause the persistence Tx_Per to be set according to the following equation:
     Tx _Per=Per_Max/( i+ 1)̂ X,  
 
 
 wherein, X is a value greater than 1 and less than 2, and Per_Max is a value between 0 and 1.