PATENT DOCUMENT

Publication Number: US-9042888-B2
Application Number: US-201113311444-A
Country: US
Kind Code: B2

Title: Mobile device network signaling management

Abstract:
A mobile wireless device maintains a radio sector database. When receiving no response or a negative response from a radio sector to a transmitted signaling message, the mobile wireless device adds or updates the radio sector database. When receiving a positive response from the radio sector, the mobile wireless device deletes the radio sector from the radio sector database. Before transmitting signaling messages to a radio sector, the mobile device determines a time delay value if the radio sector is in the radio sector database. The mobile wireless device discards the signaling message when an elapsed time since a most recently transmitted signaling message to the radio sector does not exceed the determined time delay value. In an embodiment, each radio sector in the radio sector database includes a failure count value, and the determined time delay value depends on the failure count value.

Claims:
What is claimed is: 
     
       1. A method to conserve battery power at a mobile wireless device by managing signaling connections between the mobile wireless device and a wireless network, the method comprising:
 at the mobile wireless device:
 maintaining a radio sector database identifying radio sectors from which the mobile wireless device has received at least one negative response message or no response message, in response to at least one transmitted signaling message from the mobile wireless device, wherein the radio sector database comprises a failure count value for each radio sector identified within the radio sector database; 
 receiving a trigger to transmit a signaling message to a target radio sector in the wireless network; 
 in response to determining that the target radio sector is identified within the radio sector database maintained at the mobile wireless device:
 determining a time delay value associated with the target radio sector and an elapsed time since a most recently transmitted signaling message of the mobile wireless device, wherein the determined time delay value corresponds to a failure count value for the target radio sector; and 
 comparing the elapsed time since the most recently transmitted signaling message to the determined time delay value, 
 wherein the signaling message is not transmitted to the target radio sector when the elapsed time since the most recently transmitted signaling message does not exceed the determined time delay value associated with the target radio sector; and 
 
 in response to determining that the target radio sector is not identified within the radio sector database maintained at the mobile wireless device:
 transmitting the signaling message to the target radio sector; and 
 adding an indication of the target radio sector to the radio sector database maintained at the mobile wireless device when a negative response message or no response message is received from the target radio sector via the wireless network, in response to the transmitted signaling message. 
 
 
 
     
     
       2. The method as recited in  claim 1 , wherein the failure count value is a number of failed connections with a radio sector to which the mobile wireless device is unable to establish a connection. 
     
     
       3. The method as recited in  claim 1 , further comprising transmitting the signaling message to the target radio sector when an indication of the target radio sector is in the radio sector database maintained at the mobile wireless device and the elapsed time since the most recently transmitted signaling message exceeds the determined time delay value associated with the target radio sector. 
     
     
       4. The method as recited in  claim 3 , further comprising deleting an indication of the target radio sector from the radio sector database maintained at the mobile wireless device when a positive response message is received from the target radio sector, in response to the transmitted signaling message. 
     
     
       5. The method as recited in  claim 2 , further comprising incrementing the failure count value associated with the target radio sector in the radio sector database maintained at the mobile wireless device when a negative response message or no response message is received from the target radio sector, in response to the transmitted signaling message. 
     
     
       6. The method as recited in  claim 1 , wherein the radio sector database maintained at the mobile wireless device includes at least one signal quality metric for each radio sector stored in the radio sector database, including the target radio sector, and the method further comprises storing a most recent value for at least one signal quality metric associated with the target radio sector when adding information associated with the target radio sector to the radio sector database or when updating information associated with the target radio sector in the radio sector database. 
     
     
       7. The method as recited in  claim 6 , further comprising:
 determining a current value of the at least one signal quality metric associated with the target radio sector in the radio sector database; and 
 transmitting the signaling message to the wireless network irrespective of the determined time delay value associated with the target radio sector when the determined current value of the at least one signal quality metric exceeds the stored most recent value for the at least one signal quality metric associated with the target radio sector by at least a signal quality threshold value. 
 
     
     
       8. The method as recited in  claim 1 , wherein the trigger to transmit the signaling message to the target radio sector is at least one of a location area update, a routing area update, or a tracking area update. 
     
     
       9. A mobile wireless device configured to communicate via a wireless network, the mobile wireless device comprising:
 one or more processors; 
 at least one transceiver that is configurable to communicate with one or more radio sectors via the wireless network; and 
 a radio sector database identifying problematic radio sectors from which the mobile wireless device has received a negative response message or no response message, in response to a connection request, wherein the radio sector database comprises a connection request failure count value for each radio sector identified within the radio sector database, and 
 wherein the one or more processors are operable to cause the mobile wireless device to:
 generate a request to establish a radio connection with a target radio sector of the wireless network; 
 consult the radio sector database to determine whether to establish the radio connection with the target radio sector 
 in response to determining that the target radio sector is identified within the radio sector database:
 determine a time delay value associated with the target radio sector, wherein the determined time delay value corresponds to a connection request failure count value for the target radio sector; 
 compare an elapsed time since transmitting a most recent request to establish a radio connection with the target radio sector to the determined time delay value; and 
 discard the request to establish the radio connection with the target radio sector when the elapsed time since transmitting a most recent request to establish a radio connection with the target radio sector is less than the determined time delay value; and 
 
 in response to determining that the target radio sector is not identified within the radio sector database, transmit the request to establish the radio connection with the target radio sector via the wireless network. 
 
 
     
     
       10. The mobile wireless device as recited in  claim 9 , wherein the one or more processors are further operable to cause the mobile wireless device to add an indication of the target radio sector to the radio sector database when a radio resource reject message is received from the target radio sector, in response to the transmitted request to establish the radio connection with the target radio sector. 
     
     
       11. The mobile wireless device as recited in  claim 10 , wherein the one or more processors are further operable to cause the mobile wireless device to increment the connection request failure count for the target radio sector in the radio sector database when a radio resource reject message is received from the target radio sector, in response to the transmitted request to establish the radio connection with the target radio sector. 
     
     
       12. The mobile wireless device as recited in  claim 9 , wherein an indication of each radio sector in the radio sector database comprises at least one of a location area identifier, a routing area identifier, or a tracking area identifier. 
     
     
       13. The mobile wireless device as recited in  claim 9 , wherein the one or more processors are further operable to cause the mobile wireless device to delete an indication of the target radio sector from the radio sector database when a radio resource setup message is received from the target radio sector, in response to the transmitted request to establish the radio connection with the target radio sector. 
     
     
       14. The mobile wireless device as recited in  claim 9 , wherein the one or more processors are further operable to cause the mobile wireless device to determine the time delay value associated with the target radio sector based at least in part on the connection request failure count associated with the target radio sector. 
     
     
       15. A mobile wireless device configured to communicate via a wireless network, the mobile wireless device comprising:
 one or more processors; 
 at least one transceiver that is configurable to communicate with one or more radio sectors via the wireless network; and 
 a radio sector database identifying problematic radio sectors from which the mobile wireless device has received a negative response message or no response message, in response to a connection request, wherein the radio sector database comprises a connection request failure count for each radio sector identified within the radio sector database, and 
 wherein the one or more processors are operable to cause the mobile wireless device to:
 generate a request to establish a radio connection with a target radio sector via the wireless network; 
 consult the radio sector database to determine whether to establish the radio connection with the target radio sector, wherein at least one signal quality metric is stored in the radio sector database maintained at the mobile wireless device for each radio sector in the radio sector database; and 
 in response to determining that the target radio sector is identified within the radio sector database:
 determine a current value of at least one signal quality metric associated with the target radio sector; 
 determine a time delay value associated with the target radio sector, wherein the time delay value corresponds to a connection request failure count value for the target radio sector; 
 compare an elapsed time since transmitting a most recent request to establish a radio connection with the target radio sector via the wireless network to the determined time delay value; and 
 discard the request to establish the radio connection with the target radio sector when: 
 i. the current value of the at least one signal quality metric associated with the target radio sector does not exceed a stored value of at least one signal quality metric associated with the target radio sector by at least a signal quality threshold value, and 
 ii. the elapsed time since transmitting a most recent request to establish a radio connection with the target radio sector is less than the determined time delay value. 
 
 
 
     
     
       16. The mobile wireless device as recited in  claim 15 , wherein the one or more processors are further operable to cause the mobile wireless device to add an indication of the target radio sector to the radio sector database when the target radio sector is not identified within the radio sector database and no response message is received from the target radio sector via the wireless network, in response to a transmitted request to establish the radio connection with the target radio sector. 
     
     
       17. The mobile wireless device as recited in  claim 15 , wherein the one or more processors are further operable to cause the mobile wireless device to:
 maintain the connection request failure count for each radio sector in the radio sector database; and 
 increment a connection request failure count for the target radio sector when no response message is received from the target radio sector via wireless network, in response to a transmitted request to establish the radio connection with the target radio sector. 
 
     
     
       18. The mobile wireless device as recited in  claim 15 , wherein each indication of a radio sector within the radio sector database comprises at least one of a location area identifier, a routing area identifier, or a tracking area identifier. 
     
     
       19. The mobile wireless device as recited in  claim 15 , wherein the one or more processors are further operable to cause the mobile wireless device to delete an indication of the target radio sector from the radio sector database when a radio resource setup message is received from the target radio sector via the wireless network, in response to a transmitted request to establish the radio connection with the target radio sector. 
     
     
       20. A non-transitory computer-readable medium having instructions stored thereon that, when executed at a mobile wireless device, causes the mobile wireless device to perform a method comprising:
 maintaining a radio sector database of radio sectors from which the mobile wireless device has received at least one negative response message or no response message, in response to at least one transmitted request message from the mobile wireless device; 
 maintaining a time delay database of time delay values associated with one or more failure count threshold values, wherein each of the one or more failure count threshold values is associated with a number of failed access attempts for a radio sector with which the mobile wireless device is unable to establish communications; 
 receiving a request to establish a radio connection between the mobile wireless device and a target radio sector via a wireless network; 
 determining whether to establish the radio connection with the target radio sector based at least in part on one or more radio sector properties associated with the target radio sector, wherein the one or more radio sector properties associated with the target radio sector are stored in the radio sector database or in the time delay database, and based at least in part on a comparison of an elapsed time since a most recent request to a establish a radio connection with the target radio sector to a time delay value associated with the target radio sector; 
 in response to determining not to establish the radio connection with the target radio sector, discarding the request at the mobile wireless device; and 
 in response to determining to establish the radio connection with the target radio sector:
 transmitting the request to the target radio sector; 
 adding an indication of the target radio sector to the radio sector database and updating the one or more radio sector properties associated with the target radio sector stored in the radio sector database or the time delay database when a negative response message or when no response message is received from the target radio sector via the wireless network, in response to the transmitted request; and 
 removing an indication of the target radio sector from the radio sector database when a response message is received from the target radio sector via wireless network, in response to the transmitted request. 
 
 
     
     
       21. The non-transitory computer-readable medium as recited in  claim 20 , wherein the one or more radio sector properties associated with the target radio sector comprise at least one of a local area identifier, a failure count value, or a signal quality metric. 
     
     
       22. The non-transitory computer-readable medium as recited in  claim 20 , wherein updating the one or more radio sector properties associated with the target radio sector comprises incrementing a failure count value associated with the target radio sector. 
     
     
       23. The non-transitory computer-readable medium as recited in  claim 20 , wherein removing the indication of the target radio sector from the radio sector database maintained at the mobile wireless device comprises at least one of clearing a local area identifier associated with the target radio sector from the radio sector database, clearing a signal quality metric associated with the target radio sector from the radio sector database, or resetting a failure count value associated with the target radio sector within the radio sector database. 
     
     
       24. The non-transitory computer-readable medium as recited in  claim 20 , wherein determining whether to establish the radio connection with the target radio sector further comprises:
 retrieving a failure count value associated with the target radio sector from the radio sector database maintained at the mobile wireless device; 
 determining a time delay value from information stored in the time delay database based at least in part on comparing the retrieved failure counter count value to a corresponding failure count threshold value in the time delay database; and 
 determining not to establish the radio connection between the mobile wireless device and the target radio sector when a time elapsed since a most recently transmitted request is less than the determined time delay value. 
 
     
     
       25. The non-transitory computer-readable medium as recited in  claim 24 , wherein the method further comprises:
 measuring a current signal quality value associated with the target radio sector; 
 retrieving a stored signal quality value associated with the target radio sector from the radio sector database; and 
 determining to establish the radio connection between the mobile wireless device and the target radio sector when the measured current signal quality value associated with the target radio sector exceeds the stored signal quality value associated with the target radio sector by at least a signal quality threshold value.

Description:
TECHNICAL FIELD 
     The described embodiments generally relate to methods and apparatuses for managing network signaling for mobile wireless devices. More particularly, the present embodiments describe network signaling management for mobile wireless devices to minimize power consumption during congested or poor signal quality network conditions. 
     BACKGROUND 
     Wireless networks and mobile wireless devices continue to evolve as new communication technologies develop and standardize. Current mobile wireless devices can include support to connect to one or more wireless networks that can use different wireless communication technologies. A representative mobile wireless device can include support for one or more releases of the Third Generation Partnership Project (3GPP) Global System for Mobile Communications (GSM), Universal Mobile Telecommunications System (UMTS), and/or Long Term Evolution (LTE) wireless communication standards and/or one or more releases of the Third Generation Partnership Project 2 (3GPP2) CDMA2000 1x (also referred to as 1xRTT or 1x) wireless communication standard. A representative wireless network can support connections to different mobile wireless devices that each can use one or more different wireless communication standards. 
     A mobile wireless device, upon power up initialization, can search for suitable radio sectors of one or more wireless networks that support compatible wireless communication standards with which the mobile wireless device can associate. The mobile wireless device can register with a located wireless network through one of the wireless network&#39;s radio sectors and can “camp” on the radio sector of the wireless network in an idle state. When in an idle state, no active signaling or data connections exist between the mobile wireless device and the wireless network; thus, the location of the mobile wireless device is provided to the wireless network through a periodic and/or random location update. In order to perform the initial registration of the mobile wireless device with the wireless network and also to communicate the location update to the wireless network, the mobile wireless device can send a signaling message to the wireless network to request that a signaling connection be established with the wireless network. The signaling connection can be used to transport one or more signaling messages between the mobile wireless device and the wireless network to complete the registration and/or the location update processes. Additionally, the mobile wireless device can seek to establish a signaling connection with the wireless network when there is a request for a circuit switched or packet switched connection. 
     During congested network conditions, the wireless network can reject the request from the mobile wireless device to establish the signaling connection, and the mobile wireless device can subsequently resend the request to establish the signaling connection, as without the signaling connection the information exchange required for the registration and/or location update can be unable to be completed. Each time the mobile wireless device receives a rejection from the wireless network, another signaling request can be sent. By repeatedly sending signaling connection requests to the wireless network, the mobile wireless device can drain its own limited battery resources. Similarly, when the mobile wireless device is located in an area of weak signal coverage, the mobile wireless device can receive no response from the wireless network to the request to establish the signaling connection, and again the mobile wireless device can repeatedly send the signaling request, thereby draining the battery more rapidly than desired. The mobile wireless device can also be configured to prefer connections to a wireless network that uses a later generation wireless communication protocol, such as to a 3G wireless network, over connections to an earlier generation wireless communication protocol, such as to a 2G wireless network. When rejected by or receiving no response from a more preferred 3G wireless network, the mobile wireless device can associate with a less preferred 2G wireless network and can attempt to switch back to the more preferred 3G wireless network. The mobile wireless device can repeatedly attempt to associate with the rejecting or non-responsive more preferred 3G wireless network rather than the less preferred 2G wireless network resulting in unnecessary battery drain. Thus, there exists a need for a method to manage network signaling between the mobile wireless device and the wireless network that minimizes power consumption during congested and/or poor signal quality conditions. 
     SUMMARY OF THE DESCRIBED EMBODIMENTS 
     In one embodiment, a method to conserve battery power by managing signaling connections between a mobile wireless device and a wireless network is described. The method includes at least the following steps. In a first step, the mobile wireless device maintains a radio sector database. Subsequently, the mobile wireless device receives a trigger to transmit a signaling message to a radio sector in the wireless network. When the radio sector is in the radio sector database, the mobile wireless device determines a time delay value for the radio sector and an elapsed time since a most recently transmitted signaling message. The mobile wireless device discards the signaling message when the elapsed time does not exceed the predetermined time delay value. When the radio sector is not in the radio sector database, the mobile wireless device transmits the signaling message to the radio sector in the wireless network. When receiving a negative response or receiving no response from the wireless network in response to the transmitted signaling message, the mobile wireless device adds the radio sector to the radio sector database. In an embodiment, each radio sector in the radio sector database includes a failure count value, and the determined time delay value depends on the failure count value for the radio sector. 
     In another embodiment, a mobile wireless device including a receiver and a configurable processor is described. The processor is configured to process higher layer signaling messages. The receiver is configured to transmit to and receive from the wireless network lower layer signaling messages based on the higher layer signaling messages. The processor is further configured to generate a request to establish a radio resource connection with the wireless network. The transceiver is further configured to determine whether to establish the requested radio resource connection based on a database of rejected radio sectors stored in the mobile wireless device. When the radio sector is in the database of rejected radio sectors, the transceiver is configured to determine a time delay value for the radio sector and to discard the request to establish the radio resource connection when an elapsed time since transmitting a most recent request to establish a radio resource connection with the wireless network is less than the determined time delay value for the radio sector. Otherwise, the transceiver is configured to transmit the request to establish the radio resource connection. 
     In a further embodiment, a mobile wireless device including a receiver and a configurable processor is described. The processor is configured to process higher layer signaling messages. The receiver is configured to transmit to and receive from the wireless network lower layer signaling messages based on the higher layer signaling messages. The processor is further configured to generate a request to establish a radio resource connection with the wireless network. The transceiver is further configured to determine whether to establish the requested radio resource connection based on a database of non-responsive radio sectors stored in the mobile wireless device. The transceiver is also configured to store at least one signal quality metric for each radio sector in the database of non-responsive radio sectors. When the radio sector is in the database of non-responsive radio sectors, the transceiver is configured to determine a time delay value for the radio sector and to discard the request to establish the radio resource connection when the current value for the at least one signal quality metric does not exceed the stored value for the at least one signal quality metric for the radio sector by at least a signal quality threshold value and an elapsed time since transmitting a most recent request to establish a radio resource connection with the wireless network is less than the determined time delay value for the radio sector. Otherwise, the transceiver is configured to transmit the request to establish the radio resource connection. 
     In yet a further embodiment, computer program product encoded in a non-transitory computer readable medium for managing signaling connections between a mobile wireless device and a plurality of wireless networks is described. The computer program product in the mobile wireless device includes the following computer program code. Computer program code for initializing a radio sector database and a delay database in the mobile wireless device. Computer program code for camping on or re-selecting to a radio sector in the wireless network. Computer program code for receiving a request to establish a signaling connection between the mobile wireless device and the wireless network. Computer program code for determining whether to establish the signaling connection with the radio sector based on radio sector properties of the radio sector stored in the radio sector database and in the delay database. Computer program code for discarding the request when determining not establish the signaling connection. Computer program code for transmitting the request to the radio sector when determining to establish the signaling connection. Computer program code for adding the radio sector the radio sector database and computer program code for updating radio sector properties of the radio sector stored in the radio sector database when receiving a rejection and when receiving no response from the wireless network in response to the transmitted request. Computer program code for clearing the radio sector in the radio sector database when receiving a setup message from the wireless network in response to the transmitted request. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The described embodiments and the advantages thereof may best be understood by reference to the following description taken in conjunction with the accompanying drawings. 
         FIG. 1A  illustrates components of a generic wireless communication network. 
         FIG. 1B  illustrates a mobile wireless device and several overlapping radio sectors (cells) for multiple wireless networks. 
         FIG. 2  illustrates components of a UMTS wireless communication network. 
         FIG. 3  illustrates components of a CDMA2000 1x wireless communication network. 
         FIG. 4  illustrates components of a LTE wireless communication network. 
         FIG. 5  illustrates several representative architectures for a mobile wireless communication device. 
         FIG. 6  illustrates a state transition diagram for a mobile wireless communication device for a UMTS wireless network and a GSM wireless network. 
         FIG. 7  illustrates a state transition diagram for a mobile wireless communication device for a UMTS wireless network, an LTE wireless network and a GSM wireless network. 
         FIG. 8  illustrates a state transition diagram for a mobile wireless communication device for an LTE wireless network and a CDMA2000 1x wireless network. 
         FIGS. 9 and 10  illustrate two mobile wireless devices attempting communication with several different overlapping radio sectors of a wireless network. 
         FIG. 11  illustrates a sequence of messages between the mobile wireless device and a radio access subsystem of a wireless network with an unsuccessful rejected connection request. 
         FIG. 12  illustrates a sequence of messages between the mobile wireless device and the radio access subsystem of the wireless network with an unsuccessful non-responsive connection request. 
         FIG. 13  illustrates a sequence of messages between the mobile wireless device and two different radio access subsystems from two different wireless networks. 
         FIG. 14  illustrates a representative database array for a set of radio sectors (cells) and a representative database array for delays. 
         FIG. 15  illustrates a representative method to manage signaling messaging between the mobile wireless device and one or more rejecting radio sectors (cells) in the wireless network. 
         FIG. 16  illustrates a representative method to manage signaling messaging between the mobile wireless device and one or more non-responsive radio sectors (cells) in the wireless network. 
         FIG. 17  illustrates another representative method to manage signaling messaging between the mobile wireless device and one or more rejecting radio sectors (cells) in the wireless network. 
         FIG. 18  illustrates a set of steps to determine whether to establish connections between the wireless mobile device and the wireless network. 
         FIG. 19  illustrates another representative method to manage signaling messaging between the mobile wireless device and one or more non-responsive radio sectors in the wireless network. 
     
    
    
     DETAILED DESCRIPTION OF SELECTED EMBODIMENTS 
     In the following description, numerous specific details are set forth to provide a thorough understanding of the concepts underlying the described embodiments. It will be apparent, however, to one skilled in the art that the described embodiments may be practiced without some or all of these specific details. In other instances, well known process steps have not been described in detail in order to avoid unnecessarily obscuring the underlying concepts. 
     Each of the wireless communication standards can provide a set of services for the user of the mobile wireless device, with more recent generation standards typically supporting higher uplink and downlink transmission rates. The mobile wireless device can be configured to connect preferentially to a radio sector of a wireless network that supports a later generation standard over an earlier generation standard, e.g. LTE over UMTS over GSM. 
     The examples and embodiments provided below describe various methods and apparatuses for managing network signaling between a wireless mobile device and a wireless network, and in particular to network signaling management in a mobile wireless device to minimize power consumption during congested or poor signal quality network conditions. It should be understood that implementations of the methods and apparatuses can apply to mobile wireless devices used in a variety of wireless networks. For example, the same teachings can apply to a GSM network, a UMTS network, an LTE network, a CDMA2000 1x network or any combination of these networks that can be supported by the mobile wireless device. In general, the teachings described herein can apply to a mobile wireless device operating in a cellular wireless network based on radio access technology. 
     Wireless communication network deployments continue to evolve as wireless communication network technology advances and new or updated wireless communication protocols are standardized. Circuit switched networks continue to offer voice services while packet switched networks expand from data oriented services to include a multiplicity of services including video and packet voice. Wireless mobile devices also continue to increase in functionality to supplement voice connections with multimedia internet connectivity. A typical “smart phone” can include wireless circuitry that can communicate over several different types of wireless networks including short range wireless, e.g. Bluetooth, medium range wireless, e.g. WiFi, and long range wireless, e.g. GSM, UMTS, CDMA2000 and LTE. A mobile wireless device can be designed to a particular form factor, manufacturing cost point, and power consumption requirement based on a level of integrated circuitry available that can limit the total battery life available. A user of the mobile wireless device can prefer both the increased functionality offered by more recent generation wireless protocols (e.g. higher data transfer rates) and simultaneously require maximized battery life (i.e. minimized power consumption) from the mobile wireless device. Recognizing by the mobile wireless device network conditions that can result in frequently repeated transmissions, e.g. signaling requests to initiate connections, and adapting behavior in the mobile wireless device to minimize the required number of transmissions within a given time period can reduce power consumption and thereby extend battery life of the mobile wireless device. 
     Rapid battery drain can occur when the mobile device associates with the wireless network during a registration process as well as when the mobile wireless attempts to perform a location update with the wireless network. A radio sector in the wireless network with which the mobile wireless device can be associated can respond negatively or not respond to signaling messages from the mobile wireless device, such as requests to establish a signaling connection between the mobile wireless device and the wireless network. The signaling connection can needed for the mobile wireless device to communicate registration and/or location update information to the wireless network. When receiving a negative response from the wireless network, the mobile wireless device can be redirected to continue to use the same radio sector, with or without a wait time accompanying the negative response. The mobile wireless device can subsequently reattempt to establish the signaling connection by resending the signaling messages to the same negatively responding (or to a non-responsive radio sector) of the wireless network. This cycle of transmitting signaling messages and receiving a negative response or no response can repeat many times in a relatively short time interval and can lead to unnecessary battery drain in the mobile wireless device. 
     The mobile wireless device can be unaware of the reason for the negative response or lack of response from the wireless network. Under congested network conditions, the wireless network can be unable to grant the request for a signaling connection, and under poor radio frequency signal conditions, signaling messages to or from the wireless network can be lost or corrupted during transmission. The mobile wireless device, however, can continue to send signaling messages, e.g. to request to establish a connection, as the current radio sector can have a highest priority among radio sectors with which to associate and connect. Even when the mobile wireless device can “back down” to a radio sector that uses an earlier generation wireless communication protocol, such as to a radio sector in a 2G wireless network, the mobile wireless device can re-select to the radio sector in the 3G wireless network and re-attempt to exchange signaling messages with the 3G radio sector, as the 3G wireless network can be preferred over the 2G wireless network. Under adverse network conditions, prioritization of different wireless network can cause the mobile wireless device to “bounce” between multiple radio sectors of one or more wireless networks resulting in an undesirable battery drain. 
     To recognize network conditions, the mobile wireless device can maintain one or more databases containing information about connectivity behavior for radio sectors with which the mobile wireless device is presently associated and has been previously associated. In particular, the mobile wireless device can maintain a database of radio sectors to which one or more transmitted signaling messages have returned negative responses and/or from which no response has been received. For each radio sector in the database, the mobile wireless device can include information about the radio sector, such as a unique identifier, values for one or more signal quality indicators, and a failure count that can indicate a number of successive signaling message failures. In addition, the mobile wireless device can maintain a database that relates the failure count values to time delay values. Negatively responsive and non-responsive radio sectors can be added to the one or more databases, and positively responsive radio sectors can be deleted from the one or more databases. In an embodiment, a database of negatively responsive radio sectors can be separate from a database of non-responsive radio sectors. In another embodiment, both negatively responsive and non-responsive radio sectors can be in the same database. In an embodiment, each type of signal quality indicator can have associated a signal quality threshold value. 
     The mobile wireless device can be configured to ensure that the time between successively transmitted signaling messages to a particular radio sector can depend on one or more observed and/or measured characteristics of the particular radio sector. For a negatively responsive or non-responsive radio sector, the mobile wireless device can space transmission messages further apart as the number of successive failures increases, thereby reducing the number of transmissions within a given time interval and conserving battery power. The mobile wireless device can also compare current radio frequency signal conditions for the particular radio sector, e.g. receive radio frequency signal qualities measured at the mobile wireless device, to past measurements to determine if and when changes in radio frequency conditions for the mobile wireless device within the particular radio sector occur. When radio frequency signal conditions for a non-responsive radio sector improve, the mobile wireless device can increase the frequency of transmissions to the non-responsive radio sector, as previously lost or corrupted signaling messages can be able to be received more successfully by the radio sector (and by the mobile wireless device) under the improved radio frequency signal conditions. By limiting transmissions to non-responsive radio sectors, the battery life of the mobile wireless device can be improved. 
     These and other embodiments are discussed below with reference to  FIGS. 1-19 . However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these figures is for explanatory purposes only and should not be construed as limiting. 
       FIG. 1A  illustrates a representative generic wireless communication network  100  that can include multiple mobile wireless devices  102  connected by radio links  126  to radio sectors  104  provided by a radio access network  128 . Each radio sector  104  can represent a geographic area of radio coverage emanating from an associated radio node  108  using a radio frequency carrier at a selected frequency. Radio sectors  104  can have different geometric shapes depending on antenna configuration, such as radiating outward in an approximate circle or hexagon from a centrally placed radio node  108  or cone shaped for a directional antenna from a corner placed radio node  108 . Radio sectors  104  can overlap in geographic area coverage so that the mobile wireless device  102  can receive signals from more than one radio sector  104  simultaneously. Each radio node  108  can generate one or more radio sectors  104  to which the mobile wireless device  102  can connect by one or more radio links  126 . 
     In some wireless networks  100 , the mobile wireless device  102  can be connected to more than one radio sector  104  simultaneously. The multiple radio sectors  104  to which the mobile wireless device  102  is connected can come from a single radio node  108  or from separate radio nodes  108  that can share a common radio controller  110 . A group of radio nodes  108  together with the associated radio controller  110  can be referred to as a radio access subsystem  106 . Typically each radio node  108  in a radio access subsystem  106  can include a set of radio frequency transmitting and receiving equipment mounted on an antenna tower, and the radio controller  110  connected to the radio nodes  108  can include electronic equipment for controlling and processing transmitted and received radio frequency signals. The radio controller  110  can manage the establishment, maintenance and release of the radio links  126  that connect the mobile wireless device  102  to the radio access network  128 . 
     The radio access network  128 , which provides radio frequency air link connections to the mobile wireless device  102 , connects also to a core network  112  that can include a circuit switched domain  122 , usually used for voice traffic, and a packet switched domain  124 , usually used for data traffic. Radio controllers  110  in the radio access subsystems  106  of the radio access network  128  can connect to both a circuit switching center  118  in the circuit switched domain  122  and a packet switching node  120  in the packet switched domain of the core network  112 . The circuit switching center  118  can route circuit switched traffic, such as a voice call, to a public switched telephone network (PSTN)  114 . The packet switching node  120  can route packet switched traffic, such as a “connectionless” set of data packets, to a public data network (PDN)  116 . 
       FIG. 1B  illustrates a set of overlapping radio sectors for a wireless network  130  that can use more than one radio frequency access technology. (In some wireless technologies, the term radio sector can be replaced by the term cell to indicate an area of geographic coverage. Without loss of generality, the generic term “radio sector” will be used in this application.) The mobile wireless device  102  can be associated with a serving radio sector  132  generated by a serving radio access subsystem  134 . A neighbor radio sector  140  for a neighbor radio network subsystem  138  can be within range of the mobile wireless device, albeit at a greater distance than the current serving radio access subsystem  134 . An “inter-RAT” (radio access technology) neighbor radio sector  144  generated by an inter-RAT radio access subsystem  142  can also overlap with the serving radio sector  132  and the neighbor radio sector  140 . The mobile wireless device  102  can periodically measure radio frequency signals received from each of the radio sectors  132 / 140 / 144  and can choose to change association from the current serving radio sector  132  to either the neighbor radio sector  140  or the inter-RAT neighbor radio sector based on the measured receive radio frequency signals and one or more radio sector selection criteria. The mobile wireless device  102  can be configured to prefer associating with “stronger” radio sectors having higher measured radio frequency signal quality over “weaker” radio sectors having lower measured radio frequency signal quality. The mobile wireless device  102  can be configured to attempt to switch from a “weaker” radio sector to a “stronger” radio sector, when a currently measured radio frequency signal quality value exceeds a stored measured radio frequency signal quality value by a signal quality threshold value. The mobile wireless device  102  can also be configured to prefer associating with a radio sector that uses a later generation wireless communication protocol (e.g. an LTE network) over a radio sector that uses an earlier generation wireless communication protocol (e.g. a GSM network). 
     Under acceptable network conditions, e.g. adequate radio frequency resources and good radio frequency signal quality, the mobile wireless device  102  can transfer associations between different radio sectors seamlessly. Under adverse network conditions, the mobile wireless device can be unable to receive a positive response from a preferred radio sector to one or more signaling messages. For example, the mobile wireless device  102  can be initially associated with the serving radio sector  132  and can prefer to be associated with the neighbor radio sector  140  as the receive signal quality from the neighbor radio sector  140  can be higher than the receive signal quality from the serving radio sector  140  by at least a signal quality threshold value. The neighbor radio network subsystem  138 , however, can negatively respond to signaling messages from the mobile wireless device  102  due to unspecified adverse network conditions, such as network congestion. Despite the negative response received from the neighbor radio network subsystem  138 , the mobile wireless device  102  can persist in sending signaling messages to the neighbor radio sector  140 , as the neighbor radio sector can have “higher priority” over the serving radio sector  132 . Repeatedly sending signaling messages and receiving negative responses can drain limited battery resources. Similarly when the mobile wireless device seeks to associate with the inter-RAT radio sector  144  (e.g. when the inter-RAT neighbor radio sector offers a preferred set of network capabilities), the mobile wireless device  102  can repeatedly attempt to re-select to the inter-RAT neighbor radio sector  144 , even when receiving multiple negative responses or no response from the inter-RAT neighbor radio sector  144 . As described further below, the mobile wireless device  102  can improve its battery life by recognizing the adverse network conditions and moderating the transmission of signaling messages until the network conditions improve. 
       FIG. 2  illustrates a representative UMTS wireless communication network  200  that can include one or more user equipment (UE)  202  that can communicate with a UMTS terrestrial radio access network (UTRAN)  242  that can connect to a core network (CN)  236 . The core network  236  can include a circuit switched domain  238  that can connect the UE  202  to a public switched telephone network (PSTN)  232  and a packet switched domain  240  that can connect the UE  202  to a packet data network (PDN)  234 . The UTRAN  242  can include one or more radio network sub-systems (RNS)  204 / 214  each of which can include a radio network controller (RNC)  208 / 212  and one or more Node-Bs (base stations)  206 / 210 / 216  managed by a corresponding RNC. The RNC  208 / 212  within the UTRAN  242  can be interconnected to exchange control information and manage packets received from and destined to the UE  202 . Each RNC  208 / 212  can handle the assignment and management of radio resources for the cells  244  through which the UE  202  connect to the wireless network  200  and can operate as an access point for the UE  202  with respect to the core network  236 . (Cells  244  in the UMTS network  200  can be considered equivalent to radio sectors  104  in the generic wireless communication network  100 .) The Node-B  206 / 210 / 216  can receive information sent by the physical layer of UE  202  through an uplink and transmit data to UE  202  through a downlink and can operate as access points of the UTRAN  242  for UE  202 . Signaling messages exchanged between the UE  202  and the RNS  204 / 214  in the wireless network  200  can be transported using the radio links  220  through one or more cells  244 . Setting up and tearing down the radio links  220  can be under the control of the RNC  212  in the RNS  204 , and the UE  202  can request one or more radio links  220  to transport signaling messages during registration, location updates or other maintenance processes. 
     UTRAN  242  can construct and maintain a radio access bearer (RAB) for communication between UE  202  and the core network  236 . Services provided to a specific UE  202  can include circuit switched (CS) services and packet switched (PS) services. For example, a general voice conversation can be transported through a circuit switched service, while a Web browsing application can provide access to the World Wide Web (WWW) through an internet connection that can be classified as a packet switched (PS) service. To support circuit switched services, the RNC  208 / 212  can connect to the mobile switching center (MSC)  228  of core network  236 , and MSC  228  can be connected to gateway mobile switching center (GMSC)  230 , which can manage connections to other networks, such as the PSTN  232 . To support packet switched services, the RNC  208 / 212  can also be connected to serving general packet radio service (GPRS) support node (SGSN)  224 , which can connect to gateway GPRS support node (GGSN)  226  of core network  236 . SGSN  224  can support packet communications with the RNC  208 / 212 , and the GGSN  226  can manage connections with other packet switched networks, such as the PDN  234 . A representative PDN  234  can be the “Internet”. 
       FIG. 3  illustrates a representative CDMA2000 wireless network  300  that can include elements comparable to those described earlier for the generic wireless network  100  and the UMTS wireless network  200 . Multiple mobile stations  302  can connect to one or more radio sectors  304  through radio frequency links  326 . Each radio sector  304  can radiate outward from a base transceiver station (BTS)  308  that can connect to a base station controller (BSC)  310 , together forming a base station subsystem (BSS)  306 . Multiple base station subsystems  306  can be aggregated to form a radio access network  328 . Base station controllers  310  in different base station subsystems  306  can be interconnected. The base station controllers  310  can connect to both a circuit switched domain  322  that use multiple mobile switching centers (MSC)  318  and a packet switched domain  324  formed with packet data service nodes (PDSN)  320 , which together can form a core network  312  for the wireless network  300 . As with the other wireless networks  100 / 200  described above, the circuit switched domain  322  of the core network  312  can interconnect to the PSTN  114 , while the packet switched domain  324  of the core network  312  can interconnect to the PDN  116 . As described above for the generic wireless network  100  and the UMTS wireless network  200 , signaling messages can be exchanged between the mobile station  302  and the BSS  306  in the wireless network  300  over radio links  326  through one or more radio sectors  304 . Establishing and releasing the radio links  326  can be under the control of the BSC  310  in the BSS  306 , and the mobile station  302  can request one or more radio links  326  to transport signaling messages during registration, location updates or other maintenance processes. 
       FIG. 4  illustrates a representative Long Term Evolution (LTE) wireless network  400  architecture designed as a packet switched network exclusively. A mobile terminal  402  can connect to an evolved radio access network  422  through radio links  426  associated with radio sectors  404  that emanate from evolved Node B&#39;s (eNodeB)  410 . The eNodeB  410  includes the functions of both the transmitting and receiving base stations (such as the radio nodes  108  in the generic wireless communication network  100 , the Node B  206  in the UMTS network  200  and the BTS  308  in the CDMA2000 network  300 ) as well as the base station radio controllers (such as the radio controller  110  in the generation wireless network, the RNC  212  in the UMTS network  200  and the BSC  310  in the CDMA2000 network  300 ). The equivalent core network of the LTE wireless network  400  is an evolved packet core network  420  including serving gateways  412  that interconnect the evolved radio access network  422  to public data network (PDN) gateways  416  that connect to external internet protocol (IP) networks  418 . Multiple eNodeB  410  can be grouped together to form an evolved UTRAN (eUTRAN)  406 . The eNodeB  410  can also be connected to a mobility management entity (MME)  414  that can provide control over connections for the mobile terminal  402 . Signaling messages can be exchanged between the mobile terminal  402  and the eUTRAN  406  in the wireless network  400  over radio links  426  through one or more radio sectors  404 . The eNodeB  410  can control establishing and releasing the radio links  426 . The mobile station  302  can request one or more radio links  426  to transport signaling messages during registration, location updates or other maintenance processes. 
       FIG. 5  illustrates select elements of a mobile wireless device  500 . The mobile wireless device  500  can include a transceiver  504  that can process signals according to one or more wireless communication protocols. In some embodiments, the mobile wireless device  500  can include multiple transceivers (not illustrated). The transceiver  504  can be connected to an application processor (AP)  502  that can provide higher layer functions, such requesting establishment and release of connections for various resident application services. The transceiver(s)  504  can provide lower layer functions that can support the transport of data for higher layer services ordered by the application processor  502 . In some embodiments, the AP  502  and the transceiver  504  can be part of the same integrated circuit, while in other embodiments, the AP  502  and the transceiver  504  can be separate devices. In some embodiments, the division of higher layer and lower layer functions between the AP  502  and the transceiver  504  can be flexible. In some embodiments, at least some of lower layer functions and/or management of lower layer functions can be executed by the AP  502 , with the transceiver  504  dedicated to lowest layer (e.g. physical layer) functions. The transceiver  504  can be connected to one or more antennas  506  that can transmit and receive signals according to the one or more wireless communication protocols. The use of multiple antennas for certain wireless communication protocols can provide improved performance (e.g. higher data rates or better immunity to interference) compared to a single antenna configuration. 
       FIG. 6  illustrates a state transition diagram  600  having several states for a radio resource control (RRC) portion of a protocol stack for a UE  202  in a wireless network that supports both UMTS and GSM/GPRS wireless communication protocols. The UE  202  can be in an unconnected IDLE state  624 , in a UTRA RRC connected state  610  or in a GSM/GPRS connected state  616 . In IDLE state  624 , UE  202  can request to establish a signaling connection with the wireless network. The UE  202  can use the signaling connection for communication with the wireless network, such as when registering with the network or providing location updates. In an embodiment, the signaling connection can be referred to as an RRC connection. The UE  202  can also request to establish an RRC connection in order to allocate radio resources (e.g. radio access bearers) for communication with the wireless network whenever data is available to exchange between UE  202  and the UTRAN  242 . Establishing the RRC connection can occur when an application on UE  202  requires a connection to send data or retrieve data from the network, when initiating a mobile voice connection, and when terminating a connection for the UE  202  after receiving a page on a paging channel from the UTRAN  242  or SGSN  224  indicating data available from an external data network. Once UE  202  has sent a request to UTRAN  242  to establish a radio connection, UTRAN  242  can choose a state for the RRC connection. The UTRA RRC connected state can include four separate states, CELL_DCH state  606 , CELL_FACH state  608 , CELL_PCH state  604  and URA_PCH state  602 . 
     From a UTRAN “idle” state  612  within the IDLE state  624 , UE  202  can transition to the CELL_FACH state  608 , in which it can make an initial data transfer, subsequent to which the wireless network can determine which RRC connected state to use for continued data transfer. The wireless network can move UE  202  into the Cell Dedicated Channel (CELL_DCH) state  606  or keep UE  202  in the Cell Forward Access Channel (CELL_FACH) state  608 . In CELL_DCH state  606 , a dedicated channel can be allocated to UE  202  for both uplink and downlink to exchange data. Alternatively, rather than place the UE  202  in the CELL_DCH state, UTRAN  242  can maintain UE  202  in a CELL_FACH state  608 . In a CELL_FACH state  608  no dedicated channel can be allocated to UE  202 . Instead, common channels can be used to send signaling in relatively small bursts of data. 
     The UE  202  can transition between the UTRAN “idle” state  612  to the GSM/GPRS “idle” state  614  through a process known as inter-radio access technology (RAT) reselection  622 . Transitioning by reselection  622  from the UTRAN IDLE  612  to GSM/GPRS IDLE  614  state can occur when the wireless network can be unable to support a UMTS (3G) connection and a GSM/GPRS (2G) connection can serve as a backup. The UE  202  can also transition between the UTRA “RRC connected” state  610  to the GSM/GPRS “connected” state  616  through a process referred to as inter-RAT handover  618 . For certain wireless communication protocols, a handover between one wireless network using one wireless communications technologies and a second network using a different wireless technology can occur while maintaining an active connection. For other wireless communication protocols, the handover can occur only in an idle state, i.e. active connections cannot be maintained upon handover, which can thus require releasing and establishing connections (transitions  620 ). A signaling connection between the UE  202  and the RNS  204 / 214  in the UTRAN  242  can be required to effect the establishment and release of data/voice connections (transitions  620 ) and to switch between different wireless communication protocols, e.g. inter-RAT reselection  622  in the idle state and inter-RAT handover  618  in the connected state. 
       FIG. 7  illustrates a state transition diagram  700  that extends the state transition diagram of  FIG. 6  to include states for the LTE network  400 . Transitions between an active E-UTRAN connected state  704  and the connected states of the GSM/UMTS networks can be accomplished through inter-RAT handovers  618 . Transitions between the E-UTRAN connected state  704  and the E-UTRAN idle state  702  can be effected by establishing and releasing connections  620 . Transitions between the E-UTRAN idle state  702  and the idle states of the GSM/GPRS/UMTS networks can use inter-RAT reselection  622  processes. In addition to transitions between connected states and between idle states, a mobile wireless device can also transition from a UTRA RRC connected state  610  or a GSM/GPRS connected state  616  to a E-UTRAN idle state  702  by inter-RAT reselection  622 . A mobile wireless device can also transition between the UTRA RRC connected state  610  and the GSM/GPRS connected state  616  by an inter-RAT handover as shown previously in  FIG. 6  and repeated in  FIG. 7 . 
       FIG. 8  illustrates a state transition diagram  800  between states in an LTE network  400  and a CDMA2000 1x network  300 . A mobile wireless device in the CDMA2000 1x network  300  can be in a 1xRTT/EV-DO idle state  802  and can establish and release connections  620  to transition between the /EV-DO idle state  802  and a 1xRTT/EV-DO connected state  804 . Transition between the /EV-DO idle state  802  and the E-UTRAN IDLE state  702  can be effected through an inter-RAT reselection  622  process, while transition between the 1xRTT/EV-DO connected state  804  can be realized using the inter-RAT handover  618  procedure. The inter-RAT handover  618  can permit maintaining a current active connection while transitioning between two networks that use two different wireless communication protocols. The inter-RAT reselection  622  can provide a mechanism to select between two different radio access technologies while associated with but not actively connected to one of the wireless networks  300 / 400 . 
     For any of the state transition diagrams illustrated in  FIGS. 6 ,  7  and  8 , a mobile wireless device  102  can require a signaling connection in order to register with a wireless network (i.e. to enter an idle state initially), to update a location, to establish a connection, to reselect between different radio access technologies and other functions. In addition, when reselecting between radio sectors that use the same radio access technology, the mobile wireless device  102  can also require a signaling connection to effect a transition between radio sectors in the same wireless network when the two radio sectors are located in separate locating areas, routing areas and/or tracking areas. A location area for a wireless network  100  can include multiple radio nodes  108  and one or more radio controllers  110 . Each location area can have a unique location area identity (LAI). When switching between radio sectors  104  within a location area, no update can be required; however, when switching between radio sectors  104  located in different location areas, a location area update from the mobile wireless device  102  to the wireless network  100  can be required. Crossing location area boundaries can depend on the movement of the mobile wireless device  102 , which can vary substantially for different mobile wireless devices  102  and at different times. A location area update precipitated by a change of location can be referred to as a “random” location area update. The mobile wireless device  102  can also update its location to the wireless network  100  periodically after a set time interval, and these updates can be referred to as “periodic” location area updates. 
     Some wireless networks can include “routing areas” which can differ from “location areas” in geographic coverage, where the routing area is used for packet switched data traffic and the location area is used for circuit switched voice traffic. Typically, routing areas are smaller than location areas, with multiple routing areas per location area. The mobile wireless device  102  can perform routing area updates in a similar manner to location area updates. Some wireless networks refer to these location updates more generally as tracking area updates, and the description herein can refer equally to location area updates, routing area updates and/or tracking area updates. 
       FIG. 9  illustrates a scenario  900  in which mobile wireless devices  102  attempt to establish communication with one or more radio access subsystems  106  in a set of three overlapping radio sectors  104  A, B and C. A first mobile wireless device  102  A can be positioned in a region covered by all three radio sectors  104  A, B and C, while a second mobile wireless device  102  B can be within range of only one radio sector  104  C. The first mobile wireless device  102  A can be initially not associated with any of the radio sectors  104  and can transmit one or more signaling messages, such as one or more requests (REQ) to establish a signaling connection in order to register with one or more of the radio sectors  104 . In return, each radio access subsystem  106  as shown can transmit to the mobile wireless device  102  A signaling messages that reject (REJ) the request to establish the signaling connection. A rejection can occur based on one or more network conditions, e.g. network congestion, prioritization of available radio resources and interference levels at the radio access subsystem  106  receiving the request. The mobile wireless device can continue to send requests to the wireless network and can receive rejections in a continuous cycle that can rapidly drain battery power. 
     Even after a successful registration, while in an idle state, the mobile wireless device  102  can transmit a series of requests for signaling connections and receive rejections in a rapid cycle that can consume limited available energy stored in the mobile wireless device  102 . The mobile wireless device  102  A can be associated with one of the radio sectors, e.g. radio sector  104  A emanating from radio access subsystem  106 , and can request a signaling connection in order to re-select to another radio sector  104 , e.g. radio sector  104  B or radio sector  104  C. The mobile wireless device  102  A can prefer to be associated with and/or connected to the wireless network through one of several radio sectors  104 , e.g. a radio sector  104  having the strongest signal quality as measured by the mobile wireless device  102  A. The mobile wireless device  102  A can persistently request signaling connections with the preferred radio sector  104  over a current radio sector  104  even when receiving multiple rejections to the repeated requests. This request and reject cycle can unnecessarily drain limited battery resources, when the signaling requests repeatedly fail. Similarly, battery drain can occur for any sequence of signaling messages sent persistently from the mobile wireless device  102  to the wireless network when receiving negative responses from one or more radio access subsystems in a wireless network. 
       FIG. 10  illustrates another scenario  1000  in which the mobile wireless devices  102  can receive no response from the one or more radio access subsystems  106 . Signaling messages from the mobile wireless devices  102  to the radio access subsystems  106 , e.g. requests to establish radio resource signaling connections, can be “lost” or corrupted in transmission, in which case, the radio access subsystem can provide no response to the transmitted signaling messages. Similarly, responses to the signaling messages can be transmitted by one or more of the radio access subsystems  106  but can be corrupted and/or severely attenuated during transmission and can be not received or be decodable by the mobile wireless devices  102 . In the absence of receiving a response, the mobile wireless device  102  can resend the signaling messages, e.g. requests to establish a signaling connection, requests to register the mobile wireless device  102  with the wireless network, request to setup a data or voice connection, or requests to update a current location of the mobile wireless device  102  in the wireless network. Repeated transmissions of signaling messages by the mobile wireless device  102  to non-responsive radio access subsystems  106  can result in an undesirable excessive battery drain. 
       FIG. 11  illustrates a sequence of signaling messages  1100  between the mobile wireless device  102  and the radio access subsystem  106  of the wireless network  100 , the sequence including rejected connection requests. (Initially the mobile wireless device  102  can be not attached to the wireless network  100 . The mobile wireless device  102  can send a radio resource control (RRC) connection request signaling message to the radio access subsystem  106 . The radio access subsystem  106  can respond to the RRC connection request signaling message with one of several different responses. In one response to the RRC connection request, the radio access subsystem  106  can transmit an RRC connection reject signaling message that can include a redirection indication to the mobile wireless device  102  to the same radio sector  104  of the radio access subsystem  106 . After a back-off time interval, the mobile wireless device  102  can re-transmit another RRC connection request signaling message to the radio access subsystem  106 . In another response to the RRC connection request, the radio access subsystem  106  can respond with an RRC connection reject signaling message that can include a wait time interval. After delaying transmission for the specified wait time interval, the mobile wireless device  102  can re-send an RRC connection request signaling message. When the radio access subsystem  106  chooses not to assign radio resources to the RRC connection request signaling message, the mobile wireless device  102  can transmit numerous requests and receive in turn numerous rejections. As a random back-off time period between successively transmitted requests can be relatively short, and a specified wait time can also be relatively short time intervals, persistent rejections by the radio access subsystem  106  can result in a relatively large number of transmitted RRC connection requests that can drain the battery of the mobile wireless device  102 . Thus, it can be preferred that the mobile wireless device  102  recognize this situation and temporarily delay transmissions to the radio access subsystem  106  of the wireless network  100  in order to avoid fast battery drain. 
       FIG. 12  illustrates a different scenario  1200  in which fast battery drain can occur when a series of RRC connection requests are transmitted by the mobile wireless device  102  to the radio access subsystem  106  of the wireless network  100  where no response can be received by the mobile wireless device  102 . In an embodiment, the mobile wireless device  102  can send up to a pre-determined maximum number of RRC connection requests in the absence of receiving a response from the radio access subsystem  106 , and the pre-determined maximum number can be specified by the radio access subsystem  106  of the wireless network  100 . Each request can be sent by the mobile wireless device  102  after receiving no response from the radio access subsystem  106 . After transmitting the series of RRC connection requests, the mobile wireless device  102  can wait a random back-off period of time and then resend again up to the pre-determined maximum number of RRC connection requests to the radio access subsystem  106 . Successive sequences of bursts of RRC connection requests can persist when no response is received from the radio access subsystem  106  and can result in a power consumption drain on the limited battery resources available in the mobile wireless device  102 . Thus again, it can be preferred that the mobile wireless device  102  recognize this situation and temporarily avoid transmissions to the radio access subsystem  106  of the wireless network  100  in order to avoid fast battery drain. 
       FIG. 13  illustrates another scenario  1300  during which fast battery drain can occur in the mobile wireless device  102  where one radio access subsystem  106  can be preferred to another radio access subsystem  106  by the mobile wireless device  102 ; however, the preferred radio access subsystem  106  can negatively respond or provide no response to signaling messages from the mobile wireless device  102 . Initially the mobile wireless device  102  can be not attached to either a radio access subsystem  106  A that can have a lower priority or to a radio access subsystem  106  B that can have a higher priority. Priority within the mobile wireless device  102  can be determined based on measured and/or received characteristics of the radio access subsystems  106 , such as measured receive signal properties or network service information broadcast by the radio access subsystems  106 . In a representative embodiment, the higher priority radio access subsystem  106  B can use a more recent generation wireless communication protocol, while the lower priority radio access subsystem  106  A can use an earlier generation wireless communication protocol. More recent generation wireless communication protocols can be preferred to earlier generation wireless communication protocols based on services that can be provided, e.g. higher data transmission rates or specific quality of service factors. In another representative embodiment, the mobile wireless device  102  can measure a higher receive signal quality from the higher priority radio access subsystem  106  B that exceeds a lower receive signal quality from the lower priority radio access subsystem  106  A by at least a signal quality threshold value. 
     The mobile wireless device  102  can initially send a signaling message to the higher priority radio access subsystem  106  B to request an RRC connection. The higher priority radio access subsystem  106  B can send a signaling message in response that rejects the RRC connection request, and the mobile wireless device  102  can send an RRC connection request to the lower priority radio access subsystem  106  A instead. The lower priority radio access subsystem  106  A can respond positively with an RRC connection setup signaling message to which the mobile wireless device  102  can respond with an RRC connection setup complete signaling message. The mobile wireless device  102  and the lower priority radio access subsystem  106  A can then exchange a number of signaling messages using the established RRC connection to register the mobile wireless device  102  with a wireless network through the lower priority radio access subsystem  106  A. After registration completes, the mobile wireless device  102  can be attached to the lower priority radio access subsystem  106  A in an idle state. The higher priority radio access subsystem  106  B can be still observable by the mobile wireless device  102 , and based on re-selection criteria, the mobile wireless device  102  can re-select to the higher priority radio access subsystem  106 B. The mobile wireless device  102  can then transmit an RRC connection request to the higher priority radio access subsystem  106  B to register with (and thereby complete re-selection to) the wireless network through the higher priority radio access subsystem  106  B. When an adverse network condition persists, the higher radio access subsystem  106  B can again respond negatively to the RRC connection request by sending an RRC connection reject signaling message to the mobile wireless device  102 . The mobile wireless device  102  in response can then re-select back to the lower priority radio access subsystem  106  A and repeat the registration process. This cycle of reselection and registration between radio access subsystems  106  can repeat and can thereby cause excessive battery drain. 
     In a representative embodiment, the mobile wireless device  102  can attempt to camp on a strong RF 3G radio sector  104  that rejects the mobile wireless device  102 . The mobile wireless device  102  can then camp on a lower priority 2G radio sector  104  but subsequently reselect to the strong RF 3G radio sector  104 . The strong RF 3G radio sector  104  can again reject the mobile wireless device  102 , and the cycle of rejection and reselection can repeat. As described further herein, the mobile wireless device  102  can recognize this scenario  1300  and can manage the signaling connections to reduce power consumption in the mobile wireless device  102 . 
     The scenario  1300  illustrated in  FIG. 13  in which the mobile wireless device  102  can re-select between two different radio sectors  104  of two different radio access subsystems  106  can be extended to multiple radio sectors  104 . In a representative embodiment, the mobile wireless device  102  can attempt to “camp on” and register with a radio sector  104  having a higher priority or a stronger radio frequency signal. The higher priority or “stronger RF” radio sector  104  can reject the mobile wireless device  102 , and the mobile wireless device  102  in turn can camp on and register with other radio sectors  104  that can have a lower priority and/or weaker radio frequency signals. The mobile wireless device  102  can prefer the higher priority and/or stronger RF signal radio sector  104 , resulting in a cycle of reselection. In a representative embodiment, the mobile wireless device  102  can attempt to camp on a 3G radio sector having a poor RF signal. The mobile wireless device can reselect to another radio sector, such as a limited range/service type radio sector  104  having a strong RF signal (e.g. the mobile wireless device  102  can be within range of a “femto cell”). The limited range/service type radio sector  104  can reject the mobile wireless device  102 , such as when the mobile wireless device  102  does not have permission to connect through the radio sector  104 . In response to the rejection, the mobile wireless device  102  can reselect to and register with a lower priority 2G radio sector  104 . While camped on the lower priority 2G radio sector  104 , the mobile wireless device can later reselect to either the stronger signal 3G radio sector  104  or to the limited range/service type radio sector  104  and can again be rejected by either of the “preferred” radio sectors  104 . This cycle of reselection and rejection can repeat causing a drain of battery resources in the mobile wireless device  102 . 
       FIG. 14  illustrates two database arrays  1400 / 1410 , which the mobile wireless device  102  can maintain internally, that can identify characteristics of radio sectors  104  from which negative responses or no responses have been received after the mobile wireless device  102  transmits signaling messages. Each radio sector  104  entry in a first database array  1400  can be indexed by a number that can be used to also retrieve information for the same radio sector  104 . A radio sector  104  can be represented by a location area identifier (LAI). The radio sector  104  can be entered into the database  1400  when either receiving a negative response or no response to a transmitted signaling message. A counter in the database  1400  can be incremented each successive time that a negative response or no response is received from the radio sector  104 . A radio sector  104  can be deleted from the database  1400  when a positive response is received to a transmitted signaling message. 
     In an embodiment, signal quality measurements, e.g. received signal code power (RSCP) and/or signal to noise/interference rations (EcNo) can be recorded and updated periodically for non-responsive radio sectors  104 . Signal quality threshold values can be associated with each of the signal quality measurements. Counter values for a particular radio sector  104  can be used to determine a minimum time delay between successive transmitted signaling messages to the particular radio sector  104  by the mobile wireless device  102 . A second database array  1410  can correlate time delay values with thresholds for the counter values. For a particular radio sector  104  (e.g. Radio Sector 2) having a particular counter value (e.g. Cnt 2) that does not exceed a threshold value N, the mobile wireless device  102  can ensure that at least T time units elapse between successively transmitted signaling messages to the same radio sector  104 . When the particular count value is in the range from N+1 to 2N, the mobile wireless device  102  can increase the time delay between successively transmitted signaling messages to at least 2T time units. The table of entries in the database  1410  can be pre-configured or can be adjusted dynamically depending on observed network conditions. 
     In an embodiment, the mobile wireless device  102  can measure one or more current signal quality values, e.g. current RSCP and/or EcNo of a non-responsive radio sector, and can compare the current signal quality values to previously measured and stored signal quality values in the database  1400  for the particular non-responsive radio sector  104 . When at least one (or both) of the current signal quality values exceeds previously stored signal quality values by at least an associated signal quality threshold value, the mobile wireless device  102  can transmit signaling messages to the non-responsive radio sector  104  without delay. Different signal quality metrics can be associated with different signal quality threshold values. In an embodiment, the signal quality threshold values can be pre-determined. When at least one (or both) of the current signal quality values do not exceed the previously stored signal quality values by at least the associated signal quality threshold values, the mobile wireless device  102  can be configured to delay a signaling message until at least a time delay indicated in the second database  1410  based on the counter value for the non-responsive radio sector  104  has elapsed since the last signaling message to the non-responsive radio sector  104  was transmitted. 
       FIG. 15  illustrates a representative method  1500  for signaling connection management to conserve battery power in a mobile wireless device  102 . In step  1502 , the mobile wireless device  102  maintains a database  1400  of radio sectors  104  that send negative responses to signaling messages transmitted by the mobile wireless device  102 . In step  1504 , the mobile wireless device  102  receives a trigger to transmit a signaling message to a radio sector  104  in the wireless network  100 . In step  1506 , the mobile wireless device  102  determines whether the radio sector  104  is in the radio sector database  1400 . When the radio sector  104  is in the radio sector database  1400 , the mobile wireless device  102  determines a time delay value in step  1508 . In an embodiment, the time delay value depends on a measured characteristic of the radio sector  104  (e.g. a count of negative or no responses to previously transmitted signaling messages). In step  1510 , the mobile wireless device  102  compares an elapsed time since a most recently transmitted signaling message to the radio sector  104  to the determined time delay value. When the elapsed time does not exceed the time delay value, the signaling message discards the mobile wireless device  102  in step  1512 . When the radio sector  104  is not in the negative response database  1400  or when the elapsed time exceeds the time delay value, the mobile wireless device in step  1514  transmits the signaling message to the radio sector  104 . When the mobile wireless device  102  receives a negative response to the transmitted signaling message from the radio sector  104 , in step  1518 , one or more stored values for characteristics of the radio sector  104  are added to or updated in the negative response radio sector database  1400 . When the mobile wireless device  102  receives a positive response from the radio sector  104 , entries for the radio sector in the negative response sector database  1400  are deleted. 
       FIG. 16  illustrates another representative method  1600  for signaling connection management in a mobile wireless device  102 . In step  1602 , the mobile wireless device maintains a database  1400  of non-responsive radio sectors  104 . In step  1604 , the mobile wireless device  102  receives a trigger to transmit a signaling message to a radio sector  104  in the wireless network  100 . In step  1606 , the mobile wireless device  102  determines whether the radio sector  104  is in the non-responsive radio sector database  1400 . When the radio sector  104  is in the non-responsive radio sector database  1400 , the mobile wireless device  102  determines a time delay value in step  1608 . In step  1610 , the mobile wireless device  102  compares an elapsed time since a most recently transmitted signaling message to the radio sector  104  to the determined time delay value. When the elapsed time does not exceed the time delay value, the mobile wireless device  102  in step  1612  determines a receive signal quality for the radio sector  104 . In step  1614 , the mobile wireless device compares the determined receive signal quality to a stored receive signal quality for the radio sector  104 . When the determined receive signal quality does not exceed the stored receive signal quality for the radio sector  104  by at least an associated signal quality threshold value, the mobile wireless device  102  in step  1616  discards the signaling message. When the radio sector  104  is not in the non-responsive radio sector database  1400  or when the elapsed time exceeds the determined time delay value or when the determined receive signal quality exceeds the stored receive signal quality for the radio sector  104  by at least the associated signal quality threshold value, the mobile wireless device  102  transmits the signaling message to the radio sector  104  in step  1618 . When no response is received from the radio sector  104  to the transmitting signaling message, the mobile wireless device  102  in step  1622  adds or updates entries for the radio sector  104  in the non-responsive radio sector database  1400 . When a positive response is received from the radio sector  104  to the transmitted signaling message, the mobile wireless device  102  in step  1626  deletes entries for the radio sector from the non-responsive radio sector database  1400 . 
       FIG. 17  illustrates another representative method  1700  to manage signaling connections between the mobile wireless device  102  and radio sectors  104  of the wireless network  100 . In step  1702 , the mobile wireless device initializes a radio sector database, including an area identifier and counter entry for each radio sector in the radio sector database. The mobile wireless device also initializes a delay database. In step  1704 , the mobile wireless device camps on or reselects to a radio sector  104 . In step  1706 , the mobile wireless device  102  receives an upper layer request to establish a connection between the mobile wireless device  102  and the radio sector  104 . In step  1708 , the mobile wireless device  102  determines whether to establish the connection requested by the upper layer. The determination in step  1708  depends on one or more measured and/or observed properties of the radio sector  104 . When the mobile wireless device  102  determines it is not OK to establish the requested connection, the mobile wireless device  102  discards the request to establish a connection with the radio sector  104 . When the mobile wireless device  102  determines it is OK to establish the requested connection, then in step  1712 , the mobile wireless device  102  transmits a connection establishment request to the radio sector  104  in the wireless network  100 . When receiving a rejection from the radio sector  104  in the wireless network, in step  1714 , the mobile wireless device subsequently updates entries for the radio sector in the radio sector database  1400 . In an embodiment, the mobile wireless device  102  records an area identifier of the radio sector  104  and increments a failure counter in the radio sector database. When the mobile wireless device  102  does not receive a rejection from the radio sector  104  to the transmitted connection request, the mobile wireless device  102  in step  1716  clears entries for the radio sector  104  in the radio sector database  1400 . In an embodiment, the area identifier is cleared and failure counters are reset. 
       FIG. 18  illustrates steps for a method  1800  to determine whether it is OK for the mobile wireless device  102  to establish a connection to the radio sector  104  in the wireless network  100  in response to a request to establish a connection. In step  1802 , the mobile wireless device  102  determines whether the radio sector  104  is in the radio sector database  1400 . When the radio sector  104  is not in the radio sector database  1400 , then in step  1812 , the mobile wireless device  102  determines it is OK to establish a requested connection to the radio sector  104 . When the radio sector  104  is in the radio sector database  1400 , the mobile wireless device  102  retrieves a counter for the radio sector  104  from the radio sector database  1400 . In step  1806 , the mobile wireless device  102  retrieves a delay from the delay database  1410  based on the retrieved counter value. In step  1808 , the mobile wireless device  102  determines whether the radio sector  104  requires additional delay to establish the connection based on the retrieved delay value. When no additional delay is required, the mobile wireless device  102  determines it is OK to establish a connection with the radio sector  104 . When additional delay is required, the mobile wireless device determines in step  1810  it is not OK to establish a connection to the radio sector  104 . In an embodiment, the requirement for additional delay depends on an elapsed time since a previous request to establish a connection was sent to the radio sector  104 . 
       FIG. 19  illustrates steps of another method  1900  to manage signaling connections between the mobile wireless device  102  and radio sectors  104  in the wireless network  100 . In step  1902 , the mobile wireless device initializes a radio sector database  1400  that includes an area identifier, a counter and at least one signal quality for each radio sector  104  in the radio sector database  1400 . The mobile wireless device  102  also initializes a delay database  1410 . In step  1904 , the mobile wireless device  102  camps on or reselects to a radio sector  104 . In step  1906 , the mobile wireless device  102  receives a request from an upper layer to establish a connection with the radio sector  104 . In step  1908 , the mobile wireless device  102  determines whether it is OK to establish a connection with the radio sector  104 . When it is determined to be OK to establish a connection with the radio sector  104 , the mobile wireless device  102  in step  1914  transmits a request to establish a connection with the radio sector  104 . When no response is received from the radio sector  104  in step  1916 , the mobile wireless device updates entries for the radio sector  104  in the radio sector database  1400  including recording the area identifier, incrementing the counter value and recording at least one signal quality value for the radio sector  104 . When a response is received from the radio sector, the mobile wireless device  102  in step  1918  clears entries for the radio sector  104  in the radio sector database  1400  including clearing the area identifier, resetting the counter value and clearing the at least one signal quality value. When the mobile wireless device  102  determines it is not OK to establish a signaling connection, in step  1910 , the mobile wireless device determines if at least one signal quality metric for the radio sector  104  has improved. In an embodiment, the improvement in the at least one signal quality metric can be required to be greater than an associated signal quality threshold value. When signal quality for the radio sector  104  has not improved, the request to establish a signaling connection is discarded in step  1912 . When signal quality has improved, the request to establish a signaling connection with the radio sector  104  is transmitted. 
     The various aspects, embodiments, implementations or features of the described embodiments can be used separately or in any combination. Various aspects of the described embodiments can be implemented by software, hardware or a combination of hardware and software. The described embodiments can also be embodied as computer program product encoded in a non-transitory computer readable medium. The non-transitory computer readable medium is any data storage device that can store data which can thereafter be read by a computer system. Examples of the non-transitory computer readable medium include read-only memory, random-access memory, CD-ROMs, DVDs, magnetic tape and optical data storage devices. The non-transitory computer readable medium can also be distributed over network-coupled computer systems so that the computer program product is stored and executed in a distributed fashion. 
     The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. They are not target to be exhaustive or to limit the embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings. 
     The advantages of the embodiments described are numerous. Different aspects, embodiments or implementations can yield one or more of the following advantages. Many features and advantages of the present embodiments are apparent from the written description and, thus, it is intended by the appended claims to cover all such features and advantages of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, the embodiments should not be limited to the exact construction and operation as illustrated and described. Hence, all suitable modifications and equivalents can be resorted to as falling within the scope of the invention.

Metadata:
Filing Date: 20111205
Publication Date: 20150526
Grant Date: 20150526
Priority Date: 20111205
Inventors: JUANG BEN-HENG
AYYAPPAN RAVI
WANG SHIEHLIE
Assignee: APPLE INC
CPC Classifications: [{"code": "H04W48/08", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W48/18", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y02D30/70", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W52/0222", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W52/0245", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W48/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W48/20", "inventive": true, "first": true, "tree": "[]"}, {"code": "Y02D30/70", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W24/10", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W48/18", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W52/0222", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W48/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W52/0245", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W60/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W24/10", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W48/08", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W52/02", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 48524380