Method and apparatus for performing acquisition power save mode for wireless communication systems

Abstract

Techniques to efficiently attempt acquisition of a packet data system (e.g., an IS-856 system). If a terminal has acquired one or more channels in a voice/data system (e.g., an IS-2000 system), then it can attempt acquisition on channels in the packet data system that are co-located with the acquired channels in the voice/data system. Multiple acquisition modes may be used, and on-going acquisition attempts on the co-located channels may be performed using one acquisition mode at a time in order to reduce power consumption. Acquisition attempts may be performed in a “ping-pong” manner to improve the likelihood of acquisition. For a ping-pong search, an acquisition attempt is made on the most recently acquired channel prior to an acquisition attempt on each of the remaining channels. Received signal strength estimates may also be obtained for selected channels and may be used to determine whether or not to attempt acquisition on these channels.

1 . A wireless device comprising: 
 a control unit operative to obtain information for an acquired first wireless communication system, determine one or more channels in a second wireless communication system based on the information obtained for the first system, and initiate acquisition attempts on the one or more channels in the second system; and    a demodulator operative to process the one or more channels as indicated by the control unit.    
   
   
       2 . The device of  claim 1 , further comprising: 
 a memory unit operative to store a roaming list with entries for channels in the first system, entries for channels in the second system, and information indicating which channels in the second system are co-located with which channels in the first system.    
   
   
       3 . The device of  claim 1 , wherein the information obtained for the first system indicates one or more channels in the first system which the device has acquired, and wherein the one or more channels in the second system are co-located with the one or more channels in the first system.  
   
   
       4 . The device of  claim 1 , wherein the one or more channels in the second system are sorted in an order determined by amount of elapsed time since the channels were last acquired by the device.  
   
   
       5 . The device of  claim 1 , wherein the control unit is operative to forego initiating acquisition attempts if no channels in the second system are determined based on the information obtained for the first system.  
   
   
       6 . The device of  claim 1 , wherein the control unit is operative to initiate acquisition attempts on the one or more channels using a plurality of phases, each phase being associated with a respective wait time, and wherein acquisition attempts are initiated on at least one of the one or more channels for each of the plurality of phases.  
   
   
       7 . The device of  claim 6 , wherein the control unit is operative to wait for a wait time of more than 180 seconds prior to initiating an acquisition attempt in a last phase of the plurality of phases.  
   
   
       8 . The device of  claim 1 , wherein the first system supports voice and packet data services and the second system supports packet data service.  
   
   
       9 . The device of  claim 1 , wherein the first system is an IS-2000 system and the second system is an IS-856 system.  
   
   
       10 . An apparatus comprising: 
 means for obtaining information for an acquired first wireless communication system;    means for determining one or more channels in a second wireless communication system based on the information obtained for the first system; and    means for initiating acquisition attempts on the one or more channels in the second system.    
   
   
       11 . The apparatus of  claim 10 , further comprising: 
 means for storing a roaming list with entries for channels in the first system, entries for channels in the second system, and information indicating which channels in the second system are co-located with which channels in the first system.    
   
   
       12 . The apparatus of  claim 10 , wherein the information obtained for the first system indicates one or more acquired channels in the first system, and wherein the one or more channels in the second system are co-located with the one or more acquired channels in the first system.  
   
   
       13 . A method of acquisition, comprising: 
 obtaining information for an acquired first wireless communication system;    determining one or more channels in a second wireless communication system based on the information obtained for the first system; and    initiating acquisition attempts on the one or more channels in the second system.    
   
   
       14 . The method of  claim 13 , wherein the information obtained for the first system indicates one or more acquired channels in the first system, and wherein the one or more channels in the second system are co-located with the one or more acquired channels in the first system.