System and method for coordination of wireless maintenance channel power control

Abstract

In a wireless communication system, wireless channels are maintained for communication between users and the base station. Often, a wireless user may be switched on, but not actively sending or receiving data. Accordingly, wireless users may be “active,” and currently allocated a wireless traffic channel for sending or receiving, or “idle,” and not currently sending or receiving. A wireless user may be maintained in an idle state through a periodic sequence of synchronization messages. A method for controlling a power level of a wireless message includes determining the presence of data to be transmitted, and adjusting the power level of the synchronization message depending on the presence of data. The synchronization messages corresponding to the idle state employ a lower power level than the active state transmissions which employ a higher power level. The system therefore controls the power accordingly such that synchronization messages are sent at a lower power level when no data is present, thereby reducing power consumption and interference.

What is claimed is:  
     
         1 . A method for wireless communication comprising: 
 defining at least one wireless maintenance channel operable to transmit synchronization messages, the synchronization messages having a power level;    determining the presence of data to be transmitted from a wireless access terminal; and    adjusting the power level of the synchronization message sent from the access terminal via the maintenance channel as a result of the determining the presence of data.    
     
     
         2 . The method of  claim 1  further comprising determining a data transmission state indicative of the presence or absence of data to be transmitted from a wireless access terminal.  
     
     
         3 . The method of  claim 2  further comprising computing the power level of the synchronization message in response to the data transmission state.  
     
     
         4 . The method of  claim 3  further comprising transmitting at a first power level in a first data transmission state and transmitting at a second power level in a second data transmission state.  
     
     
         5 . The method of  claim 4  wherein the first power level corresponds to an idle state wherein the synchronization messages are operable to maintain synchronization between the wireless access terminal and the base station.  
     
     
         6 . The method of  claim 1  further comprising establishing a maintenance connection over the maintenance channel, the maintenance connection operable for wireless communication of the synchronization message between a wireless access terminal and a base station.  
     
     
         7 . The method of  claim 6  wherein the maintenance channel is a pilot channel operable to transmit pilot information.  
     
     
         8 . The method of  claim 7  wherein the pilot channel is operable to transmit unmodulated signals corresponding to time tracking and power control.  
     
     
         9 . The method of  claim 1  further comprising defining at least one wireless data traffic channel operable to transmit data payload messages.  
     
     
         10 . The method of  claim 9  wherein the data traffic channels are operable to transmit modulated information corresponding to a data payload.  
     
     
         11 . The method of  claim 4  wherein the second power level corresponds to an active state wherein the synchronization messages correspond with a wireless traffic message on at least one of the data traffic channels.  
     
     
         12 . The method of  claim 4  wherein transmitting at the second power level further comprises transmitting messages having phase reference information.  
     
     
         13 . The method of  claim 2  further comprising detecting a change in the data transmission state.  
     
     
         14 . The method of  claim 2  further comprising receiving return messages in response to the synchronization messages, the return messages indicative of power control.  
     
     
         15 . The method of  claim 14  wherein the return messages are power control messages indicative of a target power level for successive messages.  
     
     
         16 . The method of  claim 15  wherein sending the synchronization messages further comprises sending from an access terminal to a base station, and sending the power control messages further comprises sending from the base station to an access terminal.  
     
     
         17 . The method of  claim 15  wherein the target power level further comprises an idle target power level and an active target power level, the idle target power level corresponding to the idle state and the active target power level corresponding to the active state.  
     
     
         18 . The method of  claim 17  wherein the active target power level is a multiple of the idle target power level.  
     
     
         19 . The method of  claim 14  further comprising ignoring the return messages for a predetermined interval after changing the data transmission state.  
     
     
         20 . The method of  claim 19  wherein the predetermined interval corresponds to a number of power control groups.  
     
     
         21 . The method of  claim 1  wherein the synchronization messages are sent in a gated manner at a gating rate.  
     
     
         22 . The method of  claim 21  wherein sending the synchronization messages in a gated manner occurs during the idle period.  
     
     
         23 . The method of  claim 1  wherein sending the synchronization messages further comprises sending over a reverse link in a wireless CDMA system.  
     
     
         24 . The method of  claim 1  wherein the maintenance channel and the data traffic channels are orthogonal wireless channels.  
     
     
         25 . The method of  claim 15  wherein the target power level is computed in response to at least one of received signal quality, Signal-to-Noise (SNR) Ratio, and Carrier-to-Interference (C/I) ratio.  
     
     
         26 . A communication system comprising: 
 at least one wireless maintenance channel operable to transmit synchronization messages, the synchronization messages having a power level;    a wireless access terminal operable to determine the presence of data to be transmitted; and    a power level controller operable to adjust the power level of the synchronization message sent from the access terminal via the maintenance channel as a result of the determining the presence of data.    
     
     
         27 . The system of  claim 26  further comprising a data transmission state indicative of the presence or absence of data to be transmitted from a wireless access terminal.  
     
     
         28 . The system of  claim 27  wherein the wireless access terminal is further operable to compute the power level of the synchronization message in response to the data transmission state.  
     
     
         29 . The system of  claim 28  wherein the power level controller is responsive to the data transmission state and operable to transmit at a first power level in a first data transmission state and transmit at a second power level in a second data transmission state.  
     
     
         30 . The system of  claim 29  wherein the first power level corresponds to an idle state wherein the synchronization messages are operable to maintain synchronization between the wireless access terminal and the base station.  
     
     
         31 . The system of  claim 26  wherein the maintenance channel is operable to maintain a maintenance connection, the maintenance connection operable for regular, periodic wireless communication of the synchronization message between the wireless access unit and a base station.  
     
     
         32 . The system of  claim 31  wherein the maintenance channel is a pilot channel operable to transmit pilot information.  
     
     
         33 . The system of  claim 32  wherein the pilot channel is operable to transmit unmodulated signals corresponding to time tracking and power control.  
     
     
         34 . The system of  claim 29  further comprising defining at least one wireless data traffic channel operable to transmit data payload messages.  
     
     
         35 . The system of  claim 34  wherein the data traffic channels are operable to transmit modulated information corresponding to a data payload.  
     
     
         36 . The system of  claim 35  wherein the second power level corresponds to an active state wherein the synchronization messages correspond with a data payload message on at least one of the data traffic channels.  
     
     
         37 . The system of  claim 36  wherein the second power level is operable to transmit synchronization messages having phase reference information.  
     
     
         38 . The system of  claim 27  further comprising a return message, the return message responsive to the synchronization messages and indicative of power control of successive messages.  
     
     
         39 . The system of  claim 38  further comprising a target power level wherein the return messages are indicative of a target power level for successive messages.  
     
     
         40 . The system of  claim 39  wherein the target power level further comprises an idle target power level and an active target power level, the idle target power level corresponding to an idle data transmission state and the active target power level corresponding to an active data transmission state.  
     
     
         41 . The system of  claim 39  wherein the return message further comprises a power step corresponding to increments of the target power level.  
     
     
         42 . The system of  claim 39  wherein the base station is further operable to detect a change in the data transmission state and recompute the target power level accordingly.  
     
     
         43 . The system of  claim 38  wherein the wireless access terminal is further operable to ignore the return messages for a predetermined interval after changing the data transmission state.  
     
     
         44 . The system of  claim 43  wherein the predetermined interval corresponds to a number of power control groups.  
     
     
         45 . The system of  claim 26  wherein the wireless access terminal is further operable to send the synchronization messages in a gated manner at a gating rate.  
     
     
         46 . The system of  claim 26  wherein the wireless access terminal is further operable to send the synchronization messages during a data transmission state of idle.  
     
     
         47 . The system of  claim 26  wherein the maintenance channel further comprises a reverse link in a wireless CDMA system.  
     
     
         48 . The system of  claim 34  wherein the maintenance channel and the data traffic channels are orthogonal wireless channels.  
     
     
         49 . The system of  claim 39  wherein the base station is further operable to compute the target power level in response to at least one of received signal quality, signal strength, perceived signal strength, Signal-to-Noise (SNR) Ratio, and Carrier-to-Interference (C/I) ratio.  
     
     
         50 . A method for controlling a power level of a wireless signal over a maintenance channel comprising: 
 providing a subscriber unit and a base station operable for wireless communications;    defining a plurality of channels for wireless communication between the base station and the subscriber unit;    establishing a maintenance link over at least one of the channels for maintaining the channel in at least an idle state, the maintenance channel operable for transmitting synchronization messages, the synchronization messages having a power level;    determining a data transmission state indicative of the presence or absence of data to be transmitted from a wireless access terminal;    computing a power level of the synchronization message based on the data transmission state; and    adjusting the power level of a message sent from the subscriber unit as a result of the computed power level.    
     
     
         51 . A computer program product having computer program code for controlling a power level of a wireless message comprising: 
 computer program code for defining at least one wireless maintenance channel operable to transmit synchronization messages, the synchronization messages having a power level;    computer program code for determining the presence of data to be transmitted from a wireless access terminal; and    computer program code for adjusting the power level of the synchronization message sent from the access terminal via the maintenance channel as a result of the determining the presence of data.    
     
     
         52 . A computer data signal having program code for controlling a power level of a wireless message comprising: 
 program code for defining at least one wireless synchronization channel operable to transmit synchronization messages, the synchronization messages having a power level;    program code for determining the presence of data to be transmitted from a wireless access terminal; and    program code for adjusting the power level of the synchronization message sent from the access terminal via the maintenance channel as a result of the determining the presence of data.    
     
     
         53 . A system for controlling the power level of a signal sent over a wireless maintenance channel comprising: 
 means for defining at least one wireless maintenance channel operable to transmit synchronization messages, the synchronization messages having a power level;    means for determining the presence of data to be transmitted from a wireless access terminal; and    means for adjusting the power level of the synchronization message sent from the access terminal via the maintenance channel as a result of the determining the presence of data.