Abstract:
An exemplary method for searching one of a plurality of systems on a multi-mode device capable of communicating on a first air interface technology and a second air interface technology is disclosed. The exemplary method includes storing a default system search period for one of the air interface technologies, such as WLAN system, receiving user input representative of a user-defined system search period for the WLAN system, storing the user-defined system search period, detecting a system search event for WLAN services, searching WLAN services in response to the system search event, and terminating the WLAN system search after expiration of the user-defined search period.

Description:
FIELD OF THE INVENTION 
   The present invention relates to the field of wireless communication devices. More specifically, the invention relates to a system scanning technique for wireless communication devices capable of a communication over a plurality of air interface technologies. 
   BACKGROUND OF THE INVENTION 
   A typical wireless communication device, such as a mobile phone, comprises, among other things, a processor coupled to a memory and to a transceiver, each enclosed in a housing. A mobile power source, such as a battery, is coupled to and supplies power to the processor, the memory and the transceiver. A speaker and a microphone are also enclosed within the housing for transmitting and receiving, respectively, acoustic signals to and from a user of the wireless communication device. The wireless communication device communicates information by transmitting and receiving electromagnetic (“EM”) energy in the radio frequency (“RF”) band via an antenna coupled to the transceiver. 
   More recently, mobile communication devices have been developed that communicate over a plurality of air interface technologies. For example, a mobile handset may be designed to incorporate both cellular telephony technology and wireless local area network (“WLAN”) technology. Such devices can be referred to as multi-mode handset devices, because of the multiple air interface modes in which the device may be configured. 
   A significant challenge facing the design and development of multi-mode devices is the ability to efficiently detect the presence of the networks associated with the various air interface technologies, particularly WLAN networks. The main reason for this difficulty is the fact that WLAN coverage is small and spotty (i.e., extremely limited geographically) compared to cellular network coverage, which is ubiquitous. Since the overall WLAN coverage within the cellular coverage region is comparatively small, the multi-mode device does not typically encounter a WLAN network when traveling. Because searching for WLAN services consumes a significant amount of power, the present technique requiring continuous searches for WLAN networks results in disadvantageously depleting the limited and precious mobile power source of multi-mode devices. 
   Other implementations provide for a fixed search time period in which to acquire WLAN services. A fixed setting (unchangeable to the user) is commonly implemented in mobile wireless communication devices in order to allow the network carrier to control the functionality and features of the device. This limitation is particularly true of system related functions, such as system searching, so that the device will have predictability in behavior. Having a fixed search time period helps conserve power, but has its own disadvantages. For example, in some cases the device will search longer than necessary and unnecessarily consume mobile power resources, as noted above. Yet in other situations, the search for WLAN service may terminate too early, thereby failing to acquire WLAN service within close proximity. 
   Accordingly, there is a strong need in the art for an efficient and optimized method for providing system searching or scanning for multi-mode wireless communication devices. 
   SUMMARY OF THE INVENTION 
   An exemplary method for searching one of a plurality of systems on a multi-mode device capable of communicating on a first air interface technology and a second air interface technology is disclosed. According to one embodiment, the method includes storing a default system search period for one of the air interface technologies, such as WLAN system, receiving user input representative of a user-defined system search period for the WLAN system, storing the user-defined system search period, detecting a system search event for WLAN services, searching WLAN services in response to the system search event, and terminating the WLAN system search after expiration of the user-defined search period. 
   According to one embodiment, the default system search period is overwritten with the user-defined system search period. In other embodiments, the default system search period and the user-defined system search period are both stored. In certain embodiments, the user-defined system search period is compared against a maximum system search period before storing the user-defined system search period in memory. 
   According to one embodiment, the method further includes receiving an update message via the other of the first and second air interface technologies. The update message may include an updated system search period. In response, the default system search period is overwritten with the updated system search period. 
   Other features and advantages of the present invention will become more readily apparent to those of ordinary skill in the art after reviewing the following detailed description and accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  illustrates a network arrangement including an exemplary multi-mode wireless communication device according to one embodiment of the present invention. 
       FIGS. 2 and 3  illustrate exemplary data structures for storing system searching parameters according to various embodiments of the invention. 
       FIG. 4  illustrates an exemplary flowchart for providing system searching for a multi-mode device according to one embodiment of the invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring first to  FIG. 1 , there is shown network arrangement  100  including exemplary multi-mode wireless communication device  110  according to one embodiment of the present invention. By way of example, multi-mode device  110  may be a mobile phone capable of communicating over two or more radio access technologies. According to one particular embodiment, multi-mode device  110  is capable of communicating over one of the several of cellular networks  112  in accordance with code division multiple access (CDMA), Global System for Mobile Communications (GSM), WCDMA, or other Wireless Wide Area Networks (WWAN) standard, for example, and is further capable of communication over one of the several packet data networks  114  in accordance Wireless Local Area Networks (WLAN) protocols, for example. 
   As shown in  FIG. 1 , multi-mode device  110  comprises processor  116  coupled to memory  118  and to first transceiver  120  and second transceiver  122 . Programming is stored in memory  118  and executed by processor  116  for the operation of multi-mode device  110 . The details of the operation of multi-mode device  110  are described more fully below in conjunction with  FIGS. 2 through 4 . First transceiver  120  is coupled to antenna  124  for communication with network  112 , and second transceiver  122  is coupled to antenna  16  for communication with network  114 . Processor  116  is also coupled to interface  128 , which may further be coupled to one or more user-interface (UI) devices (not shown), such as a display device, input keys, a microphone, and a speaker, for example. 
   Referring next to  FIGS. 2 and 3 , there are shown exemplary data structures  200  and  300  for storing system search parameters according various embodiments of the invention. As noted above in conjunction with  FIG. 1 , memory  118  of multi-mode device  110  stores programming executed by processor  116  during operation. Memory  118  may also store a number of settings or parameters used to configure operation of multi-mode device  110 . Similarly, data structure  200  (or data structure  300 ), which defines system search parameters, is stored in memory  118 . Other WLAN network parameters, such as geographical information (“GEO”) association tags, authentication and authorization parameters, are also typically stored in memory  118 . 
   Data structure  200  depicts one exemplary arrangement for storing system search parameters according to one embodiment. More particularly, data structure  200  defines system search period parameters for one of the two air interface technologies associated with transceivers  120  and  122  of multi-mode device  110 . In the present example, data structure  200  defines the system search period parameters for WLAN interface  122 . Thus, reference  222  of data structure  200  may include a reference to identify “WLAN” or transceiver  122 , for example. Parameters  224 A- 224 E may identify Service Set Identifiers (“SSIDs”), parameters  226 A- 226 E may identify a system search period for corresponding SSIDs  224 A- 224 E, and parameters  228 A- 228 E may identify whether a corresponding system search period  226 A- 226 E is enabled for user-defined values. 
   By way of illustration, system search period  226 A may be used to store a default system search period for searching the WLAN systems associated with SSID  224 A, and enabled flag  228 A may indicated whether system search period  226 A may be replaced with a user-defined system search period. In this particular embodiment, if enabled flag  228 A is set, then the user is able to input and store a user-defined value in system search period parameter  226 A for SSID  224 A. Each of SSID  224 B- 224 E has a corresponding system search period  226 B- 226 E and enabled flag  228 B- 228 E. In some cases, the same default system search period may be used for all SSIDs; however data structure  200  provides the ability to define a distinct default system search period for each SSID. 
   In operation, the system search algorithm executed by processor  116 , when activated, attempts to search for and acquire the system associated with SSIDs  224 A- 224 E for the system search period defined by corresponding parameter  226 A- 226 E, whether default, or user-defined. SSID values  224 A- 224 E, default search periods  226 A- 226 E, and enabled flags  228 A- 228 E may be initially defined when multi-mode device  110  is provisioned and/or updated during subsequent updates (e.g., over-the-air service and repair messages via cellular network  112 ) from the network carrier. In some embodiments, certain SSIDs (e.g.,  224 D- 224 E) may be identified as user-defined or “ad-hoc” in which case, messages from the network carrier do not modify or update its associated values. 
   Various algorithms for system searching would benefit from the flexibility provided by data structure  200  since the user, will have greater control over defining the system search period in accordance with the conditions proximate multi-mode device  110 , as described more fully below in conjunction with  FIG. 4 . 
   Data structure  300  of  FIG. 3  illustrates another exemplary arrangement for storing system search parameters according to one embodiment. By way of illustration and similar to data structure  200  of  FIG. 2 , data structure  300  defines the system search period parameters for WLAN interface  122  of  FIG. 1 . Thus, reference  322  of data structure  300  may include a reference to identify “WLAN” or transceiver  122 , for example. Parameters  224 A and  224 B may identify a particular SSID, parameter  226 A may identify a default system search period for SSID  224 A, and parameter  226 B may identify a user-defined system search period for SSID  224 A. Parameter  328 A may identify whether user-defined system search period  226 B is enabled for input and/or modification. Similarly, parameter  226 C may identify a default system search period for SSID  224 B, parameter  226 D may identify a user-defined system search period for SSID  224 B, and parameter  328 B may identify whether user-defined system search period  226 D is enabled for input/modification. Data structure  300  differs from data structure  200  in that default system search period data  326 A and  326 C can be preserved even if user-defined system search period data  326 B and  326 D are stored. It is noted that data structures  200  and  300  are only exemplary, and other data structures for storing system search parameters may be utilized in accordance with the present invention. 
   In a more complex example, memory  118  can store additional search parameters, such as the frequency of searching when in the search window. In addition, the search frequency attenuation factor (where search frequency is not constant over time) can also be stored in memory. In these cases, the user may be able to define a user-defined search frequency and/or search attenuation factors for one or more SSIDs, and stored in corresponding parameters in data structure  200  or  300 . 
   It is further noted that although in the example data structures of  200  and  300 , user-defined search periods are uniquely assigned to particular SSIDs, in other embodiments, the user-defined search period can be defined to correspond to the search period or search window for searching all SSIDs for a particular system search event. 
   Referring next to  FIG. 4 , there is shown exemplary flowchart  400  for providing system searching for a multi-mode device according to one embodiment of the invention. The multi-mode system searching technique depicted in  FIG. 4  may be implemented in multi-mode device  110  of  FIG. 1 , for example. Certain details and features have been left out of flow chart  400  of  FIG. 4  that would apparent to a person of ordinary skill in the art having the benefit of the present disclosure. For example, a step may consist of one or more sub-steps, as known in the art. While blocks  402  through  418  shown in flow chart  400  are sufficient to describe one embodiment of the present invention, other embodiments of the invention may utilize operations different from those shown in flow chart  400 . 
   At block  402 , the default system search period for acquiring the WLAN system is stored in memory  118  of multi-mode device  110 . For example default search periods may be stored in parameters  226 A- 226 E in data structure  200  in  FIG. 2  or parameters  326 A and  326 C in data structure  300  of  FIG. 3 . As noted above, the default system search period may be defined initially during provisioning of multi-mode device  100 . 
   At block  403 , an update message via cellular network  112  is received by multi-mode device  110 . The update message may include an update to one or more of the default system search periods or update flags initially stored during block  402 , and/or may include one or more new sets of system search parameters (SSID, system search period, enabled flag). Responsive to the received update message, processor  116  stores the updated and/or new system search parameters in memory  118  (e.g., in data structure  200  or  300 ). 
   At block  404 , user input representative of a user-defined system search period is received by multi-mode device  100 . The user is able to specify a user-defined system search period for a particular SSID if permitted to do so, typically by the network carrier or multi-mode handset manufacturer. In the data structure examples discussed above in conjunction with  FIGS. 2 and 3 , an enabled flag can be set to indicate whether the user is able to specify a user-defined system search period for one or more systems. User input of the user-defined system search period can be received via I/O devices, such as keypads or touchscreen displays, for example, in response to prompts communicated to the user via a display screen. 
   At decision block  406 , the received user-defined system search period can be compared to a maximum search period. For example, the maximum search period can be provisioned by network carrier of network  112  and stored in memory  118  during provisioning of multi-mode device  110  and/or updated via over the air messages over network  112 . Updates to the search periods may be provided by the network carrier if, for example, the network carriers obtains updated information indicative of the such information as signal strength, coverage area, load, etc., of a specific SSID. If the user-defined system search period does not exceed the maximum search period, the user-defined system search period is stored in memory  118  at block  408 . In other embodiments, the comparison against a maximum system search period can be omitted, e.g., in a situation where it is desirable to allow the user to specify a continuous search (without limit). If the maximum search period is exceed at block  406 , the user may be requested to enter another value (not shown). 
   At block  410 , if a system search event is detected, an attempt to search and acquire WLAN service is initiated at block  412 . Examples of system search events include a user-initiated command to search for WLAN, automatic search triggering event based on network conditions in cellular network  112 , commands issued by the network carrier via network  112 , and multi-mode device  110  start-up, among others. 
   At decision block  414 , if a WLAN network  114  is successfully acquired, authenticated and authorized, the system search is terminated at block  418 , and multi-mode device  110  functions as a WLAN radio. It some cases, multi-mode device  110  may operate simultaneously as a cellular radio at the same time as the WLAN radio, or in a hybrid mode where the cellular radio is only periodically activated. 
   If at decision block  414  a WLAN network  114  is not successfully acquired, authenticated or authorized, a decision at block  416  is made as to whether a system search period has been exceeded. A timer may be used to determine the length of the current system search period. If a user-defined system search period is not defined or is not enabled, the current search period is compared to the default system search period, but the user-defined system search period is enabled and defined, the current search period is compared to the user-defined system search period. If the system search period (default or user-defined) is exceeded, the system search is terminated at block  418 ; otherwise, search for WLAN service continues at block  412 . In one embodiment, if the search is terminated due to expiration of the system search period, multi-mode device  110  will not initiate a new search for WLAN service until the user or the cellular network  112  initiates a new search. 
   Advantageously, system searching for multi-mode devices is improved. Flexibility given to the user, when enabled, allows the user to define search parameters based on the current conditions surrounding multi-mode device  110 , while retaining network carrier control of the important device settings. For example, allowing the user to extend the search periods allows the user to acquire WLAN services in a known coverage area where a static search period may have terminated the search prematurely. Conversely, allowing the user to limit the search period in areas with known limited WLAN services can significantly reduce unnecessary system searches, thereby extending valuable mobile power resources. 
   From the above description of exemplary embodiments of the invention, it is manifest that various techniques can be used for implementing the concepts of the present invention without departing from its scope. Moreover, while the invention has been described with specific reference to certain embodiments, a person of ordinary skill in the art would recognize that changes could be made in form and detail without departing from the spirit and the scope of the invention. The described exemplary embodiments are to be considered in all respects as illustrative and not restrictive. It should also be understood that the invention is not limited to the particular exemplary embodiments described herein, but is capable of many rearrangements, modifications, and substitutions without departing from the scope of the invention.