System scanning method and arrangement for mobile wireless communication devices

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.

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.

DETAILED DESCRIPTION OF THE INVENTION

Referring first toFIG. 1, there is shown network arrangement100including exemplary multi-mode wireless communication device110according to one embodiment of the present invention. By way of example, multi-mode device110may be a mobile phone capable of communicating over two or more radio access technologies. According to one particular embodiment, multi-mode device110is capable of communicating over one of the several of cellular networks112in 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 networks114in accordance Wireless Local Area Networks (WLAN) protocols, for example.

As shown inFIG. 1, multi-mode device110comprises processor116coupled to memory118and to first transceiver120and second transceiver122. Programming is stored in memory118and executed by processor116for the operation of multi-mode device110. The details of the operation of multi-mode device110are described more fully below in conjunction withFIGS. 2 through 4. First transceiver120is coupled to antenna124for communication with network112, and second transceiver122is coupled to antenna16for communication with network114. Processor116is also coupled to interface128, 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 toFIGS. 2 and 3, there are shown exemplary data structures200and300for storing system search parameters according various embodiments of the invention. As noted above in conjunction withFIG. 1, memory118of multi-mode device110stores programming executed by processor116during operation. Memory118may also store a number of settings or parameters used to configure operation of multi-mode device110. Similarly, data structure200(or data structure300), which defines system search parameters, is stored in memory118. Other WLAN network parameters, such as geographical information (“GEO”) association tags, authentication and authorization parameters, are also typically stored in memory118.

Data structure200depicts one exemplary arrangement for storing system search parameters according to one embodiment. More particularly, data structure200defines system search period parameters for one of the two air interface technologies associated with transceivers120and122of multi-mode device110. In the present example, data structure200defines the system search period parameters for WLAN interface122. Thus, reference222of data structure200may include a reference to identify “WLAN” or transceiver122, for example. Parameters224A-224E may identify Service Set Identifiers (“SSIDs”), parameters226A-226E may identify a system search period for corresponding SSIDs224A-224E, and parameters228A-228E may identify whether a corresponding system search period226A-226E is enabled for user-defined values.

By way of illustration, system search period226A may be used to store a default system search period for searching the WLAN systems associated with SSID224A, and enabled flag228A may indicated whether system search period226A may be replaced with a user-defined system search period. In this particular embodiment, if enabled flag228A is set, then the user is able to input and store a user-defined value in system search period parameter226A for SSID224A. Each of SSID224B-224E has a corresponding system search period226B-226E and enabled flag228B-228E. In some cases, the same default system search period may be used for all SSIDs; however data structure200provides the ability to define a distinct default system search period for each SSID.

In operation, the system search algorithm executed by processor116, when activated, attempts to search for and acquire the system associated with SSIDs224A-224E for the system search period defined by corresponding parameter226A-226E, whether default, or user-defined. SSID values224A-224E, default search periods226A-226E, and enabled flags228A-228E may be initially defined when multi-mode device110is provisioned and/or updated during subsequent updates (e.g., over-the-air service and repair messages via cellular network112) from the network carrier. In some embodiments, certain SSIDs (e.g.,224D-224E) 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 structure200since the user, will have greater control over defining the system search period in accordance with the conditions proximate multi-mode device110, as described more fully below in conjunction withFIG. 4.

Data structure300ofFIG. 3illustrates another exemplary arrangement for storing system search parameters according to one embodiment. By way of illustration and similar to data structure200ofFIG. 2, data structure300defines the system search period parameters for WLAN interface122ofFIG. 1. Thus, reference322of data structure300may include a reference to identify “WLAN” or transceiver122, for example. Parameters224A and224B may identify a particular SSID, parameter226A may identify a default system search period for SSID224A, and parameter226B may identify a user-defined system search period for SSID224A. Parameter328A may identify whether user-defined system search period226B is enabled for input and/or modification. Similarly, parameter226C may identify a default system search period for SSID224B, parameter226D may identify a user-defined system search period for SSID224B, and parameter328B may identify whether user-defined system search period226D is enabled for input/modification. Data structure300differs from data structure200in that default system search period data326A and326C can be preserved even if user-defined system search period data326B and326D are stored. It is noted that data structures200and300are 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, memory118can 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 structure200or300.

It is further noted that although in the example data structures of200and300, 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 toFIG. 4, there is shown exemplary flowchart400for providing system searching for a multi-mode device according to one embodiment of the invention. The multi-mode system searching technique depicted inFIG. 4may be implemented in multi-mode device110ofFIG. 1, for example. Certain details and features have been left out of flow chart400ofFIG. 4that 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 blocks402through418shown in flow chart400are sufficient to describe one embodiment of the present invention, other embodiments of the invention may utilize operations different from those shown in flow chart400.

At block402, the default system search period for acquiring the WLAN system is stored in memory118of multi-mode device110. For example default search periods may be stored in parameters226A-226E in data structure200inFIG. 2or parameters326A and326C in data structure300ofFIG. 3. As noted above, the default system search period may be defined initially during provisioning of multi-mode device100.

At block403, an update message via cellular network112is received by multi-mode device110. The update message may include an update to one or more of the default system search periods or update flags initially stored during block402, 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, processor116stores the updated and/or new system search parameters in memory118(e.g., in data structure200or300).

At block404, user input representative of a user-defined system search period is received by multi-mode device100. 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 withFIGS. 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 block406, 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 network112and stored in memory118during provisioning of multi-mode device110and/or updated via over the air messages over network112. 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 memory118at block408. 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 block406, the user may be requested to enter another value (not shown).

At block410, if a system search event is detected, an attempt to search and acquire WLAN service is initiated at block412. Examples of system search events include a user-initiated command to search for WLAN, automatic search triggering event based on network conditions in cellular network112, commands issued by the network carrier via network112, and multi-mode device110start-up, among others.

At decision block414, if a WLAN network114is successfully acquired, authenticated and authorized, the system search is terminated at block418, and multi-mode device110functions as a WLAN radio. It some cases, multi-mode device110may 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 block414a WLAN network114is not successfully acquired, authenticated or authorized, a decision at block416is 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 block418; otherwise, search for WLAN service continues at block412. In one embodiment, if the search is terminated due to expiration of the system search period, multi-mode device110will not initiate a new search for WLAN service until the user or the cellular network112initiates 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 device110, 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.