Patent Abstract:
One illustrative technique for use in a mobile device having a visual display includes monitoring an operating temperature at the device and, when the monitored operating temperature is greater than a first threshold temperature, allowing only emergency communication and providing a visual indication indicating that only emergency communication is allowed.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of and claims priority to U.S. non-provisional patent application having application Ser. No. 13/150,703 and filing date of 1 Jun. 2011, now U.S. Pat. No. 8,238,871, which is a continuation of and claims priority to U.S. non-provisional patent application having application Ser. No. 12/704,052 and filing date of 11 Feb. 2010, now U.S. Pat. No. 8,045,969, which is a continuation of and claims priority to application having application Ser. No. 11/683,283 and filing date of 7 Mar. 2007, now U.S. Pat. No. 7,689,256, which is a continuation of and claims priority to application having application Ser. No. 10/704,846 and filing date of 10 Nov. 2003, now U.S. Pat. No. 7,206,567, each application being hereby incorporated by reference herein. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     The present invention relates generally to mobile communication devices which operate in wireless communication networks, and more particularly to methods and apparatus for limiting communication capabilities at the mobile device based on predetermined conditions detected at the mobile device. 
     2. Description of the Related Art 
     Modern-day mobile communication devices which operate in wireless communication networks provide end users with the ability to place and receive two-way voice calls, send and receive text messages and e-mail messages, and send and receive other information such as Internet data. Such communication devices utilize a radio frequency (RF) transceiver for transmitting and receiving such information. 
     Unfortunately, adverse conditions (such as adverse temperature conditions) may compromise the performance or utility of the mobile device. For example, when a mobile device is communicating information with use of its RF transceiver, the RF transceiver heats up and its temperature rises. If the temperature of the RF transceiver is outside certain specification parameters, the RF transceiver undesirably emits spurious signals at unacceptable levels. These spurious signals may be outside certain standards, such as those established by the Federal Communications Commission (FCC) or Industry Canada, for example, and/or cause interference with other communications in the network. In addition, if the temperature of a rechargeable battery of the mobile device is outside certain specification parameters for too long, the battery may experience permanent damage and require replacement or could even explode. 
     Under such adverse conditions, the mobile station could power down its circuitry and inhibit all communications, but the end user would be left with no ability to communicate information. This would be undesirable in at least some circumstances, such as in emergency situations. What are needed are methods and apparatus which overcome the deficiencies of current practices. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of present invention will now be described by way of example with reference to attached figures, wherein: 
         FIG. 1  is a block diagram which illustrates pertinent components of a mobile communication device which communicates within a wireless communication network; 
         FIG. 2  is a more detailed diagram of a preferred mobile communication device of  FIG. 1 ; 
         FIG. 3  is a state diagram showing various communicating states of the mobile communication device of  FIGS. 1 and 2 ; and 
         FIG. 4  is a flowchart for describing a method of limiting communication capabilities in the mobile communication device of  FIGS. 1 and 2 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  is a block diagram of a communication system  100  which includes a mobile station  102  which communicates through a wireless communication network  104 . Mobile station  102  preferably includes a visual display  112 , a keyboard  114 , and perhaps one or more auxiliary user interfaces (UI)  116 , each of which is coupled to a controller  106 . Controller  106  is also coupled to radio frequency (RF) transceiver circuitry  108  and an antenna  110 . 
     Typically, controller  106  is embodied as a central processing unit (CPU) which runs operating system software in a memory component (not shown). Controller  106  will normally control overall operation of mobile station  102 , whereas signal processing operations associated with communication functions are typically performed in RF transceiver circuitry  108 . Controller  106  interfaces with device display  112  to display received information, stored information, user inputs, and the like. Keyboard  114 , which may be a telephone type keypad or full alphanumeric keyboard, is normally provided for entering data for storage in mobile station  102 , information for transmission to network  104 , a telephone number to place a telephone call, commands to be executed on mobile station  102 , and possibly other or different user inputs. 
     Mobile station  102  sends communication signals to and receives communication signals from network  104  over a wireless link via antenna  110 . RF transceiver circuitry  108  performs functions similar to those of a radio network (RN)  128 , including for example modulation/demodulation and possibly encoding/decoding and encryption/decryption. It is also contemplated that RF transceiver circuitry  108  may perform certain functions in addition to those performed by RN  128 . It will be apparent to those skilled in art that RF transceiver circuitry  108  will be adapted to particular wireless network or networks in which mobile station  102  is intended to operate. 
     Mobile station  102  may consist of a single unit, such as a data communication device, a cellular telephone, a multiple-function communication device with data and voice communication capabilities, a personal digital assistant (PDA) enabled for wireless communication, or a computer incorporating an internal modem. Alternatively, mobile station  102  may be a multiple-module unit comprising a plurality of separate components, including but in no way limited to a computer or other device connected to a wireless modem. In particular, for example, in the mobile station block diagram of  FIG. 1 , RF transceiver circuitry  108  and antenna  110  may be implemented as a radio modem unit that may be inserted into a port on a laptop computer. In this case, the laptop computer would include display  112 , keyboard  114 , one or more auxiliary UIs  116 , and controller  106  embodied as the computer&#39;s CPU. It is also contemplated that a computer or other equipment not normally capable of wireless communication may be adapted to connect to and effectively assume control of RF transceiver circuitry  108  and antenna  110  of a single-unit device such as one of those described above. Such a mobile station  102  may have a more particular implementation as described later in relation to mobile station  202  of  FIG. 2 . 
     Mobile station  102  includes a battery interface  122  for receiving one or more rechargeable batteries  124  or a battery pack. Battery  124  provides electrical power to electrical circuitry in mobile station  102 , and battery interface  122  provides for a mechanical and electrical connection for battery  124 . Battery interface  122  is coupled to a regulator  126  which regulates power to the device. Mobile station  102  also operates using a memory module  120 , such as a Subscriber Identity Module (SIM) or a Removable User Identity Module (R-UIM), which is connected to or inserted in mobile station  102  at an interface  118 . As an alternative to a SIM or an R-UIM, mobile station  102  may operate based on configuration data programmed by a service provider into a memory module within controller  106  which is a non-volatile memory. 
     Mobile station  102  also includes one or more temperature sensors and a battery voltage sensor  154  which are used to control its operational states and communication capabilities (described later in detail in relation to  FIGS. 3-4 ). In the present embodiment, two temperature sensors are included in mobile station  102 . One temperature sensor  150  is located adjacent RF transceiver  108  and, more specifically, adjacent to a power amplifier (PA) of RF transceiver  108 . Temperature sensor  150  is coupled to controller  106  which continually monitors a temperature from temperature sensor  150 . Temperature sensor  150  may be, for example, a thermistor having a resistance which varies in accordance with temperature changes which are detected as voltage changes at controller  106 . When mobile station  102  is communicating information with use of RF transceiver  108  (e.g. with its transmitter on), for example, RF transceiver  108  heats up and its temperature rises. The ambient temperature also affects the operating temperature of RF transceiver  108 . If the temperature of RF transceiver  108  is outside certain specification parameters, spurious signals would be undesirably emitted at unacceptable levels. However, mobile station  102  operates to eliminate or reduce the possibility of such occurrences as will be described later below in relation to  FIGS. 3 and 4 . 
     Note that, although only a single temperature sensor  150  is shown and described for RF transceiver  108 , a temperature sensor may be utilized for each one of multiple PAs in mobile station  102  which correspond to multiple frequency bands within which the mobile station  102  may operate (e.g. cellular band, PCS band, etc.). 
     Another temperature sensor  152  may be located in battery or battery pack  124 . Temperature sensor  152  is coupled to controller  106  through battery interface  122 . Temperature sensor  152  may be, for example, a thermistor which fluctuates its resistance in accordance with changes in temperature to provide a change in voltage which is detected at controller  106 . When mobile station  102  is communicating information with use of RF transceiver  108  (e.g. with its transmitter on), for example, battery  124  heats up and its temperature rises. The ambient temperature also affects the temperature of battery  124 . If the temperature of battery  124  is outside certain specification parameters for too long of a time period, battery  124  may experience permanent damage and require replacement or could even explode. However, mobile station  102  operates to eliminate or reduce the possibility of such occurrences as will be described later below in relation to  FIGS. 3 and 4 . 
     Battery voltage sensor  154  is also coupled to controller  106  through battery interface  122 . Battery voltage sensor  154  may be implemented using an analog-to-digital (A/D) converter, for example. Battery voltage sensor  154  is used to continually measure the voltage of battery  256 , so that controller  106  may appropriately control RF transceiver  108 . In particular, when the battery voltage becomes low, mobile station  102  operates to limit the use of RF transceiver  108  to extend the life of battery  124  as will be described later below. 
     Mobile station  102  communicates in and through wireless communication network  104 . In the embodiment of  FIG. 1 , wireless network  104  is a Third Generation (3G) supported network based on Code Division Multiple Access (CDMA) technologies. In particular, wireless network  104  is a Cdma2000™ network which includes fixed network components coupled as shown in  FIG. 1 . Cdma2000™ is a trademark of the Telecommunications Industry Association (TIA). Wireless network  104  of the Cdma2000™ type includes a Radio Network (RN)  128 , a Mobile Switching Center (MSC)  130 , a Signaling System 7 (SS7) network  140 , a Home Location Register/Authentication Center (HLR/AC)  138 , a Packet Data Serving Node (PDSN)  132 , an IP network  134 , and a Remote Authentication Dial-In User Service (RADIUS) server  136 . SS7 network  140  is communicatively coupled to a network  142  (such as a Public Switched Telephone Network or PSTN), whereas IP network is communicatively coupled to a network  144  (such as the Internet). 
     During operation, mobile station  102  communicates with RN  128  which performs functions such as call-setup, call processing, and mobility management. RN  128  includes a plurality of base station transceiver systems that provide wireless network coverage for a particular coverage area commonly referred to as a “cell”. A given base station transceiver system of RN  128 , such as the one shown in  FIG. 1 , transmits communication signals to and receives communication signals from mobile stations within its cell. The base station transceiver system normally performs such functions as modulation and possibly encoding and/or encryption of signals to be transmitted to the mobile station in accordance with particular, usually predetermined, communication protocols and parameters, under control of its controller. The base station transceiver system similarly demodulates and possibly decodes and decrypts, if necessary, any communication signals received from mobile station  102  within its cell. Communication protocols and parameters may vary between different networks. For example, one network may employ a different modulation scheme and operate at different frequencies than other networks. The underlying services may also differ based on its particular protocol revision. 
     The wireless link shown in communication system  100  of  FIG. 1  represents one or more different channels, typically different radio frequency (RF) channels, and associated protocols used between wireless network  104  and mobile station  102 . An RF channel is a limited resource that must be conserved, typically due to limits in overall bandwidth and a limited battery power of mobile station  102 . Those skilled in art will appreciate that a wireless network in actual practice may include hundreds of cells depending upon desired overall expanse of network coverage. All pertinent components may be connected by multiple switches and routers (not shown), controlled by multiple network controllers. 
     For all mobile station&#39;s  102  registered with a network operator, permanent data (such as mobile station  102  user&#39;s profile) as well as temporary data (such as mobile station&#39;s  102  current location) are stored in a HLR/AC  138 . In case of a voice call to mobile station  102 , HLR/AC  138  is queried to determine the current location of mobile station  102 . A Visitor Location Register (VLR) of MSC  130  is responsible for a group of location areas and stores the data of those mobile stations that are currently in its area of responsibility. This includes parts of the permanent mobile station data that have been transmitted from HLR/AC  138  to the VLR for faster access. However, the VLR of MSC  130  may also assign and store local data, such as temporary identifications. Mobile station  102  is also authenticated on system access by HLR/AC  138 . In order to provide packet data services to mobile station  102  in a Cdma2000™ based network, RN  128  communicates with PDSN  132 . PDSN  132  provides access to the Internet  144  (or intranets, Wireless Application Protocol (WAP) servers, etc.) through IP network  134 . PDSN  132  also provides foreign agent (FA) functionality in mobile IP networks as well as packet transport for virtual private networking. PDSN  132  has a range of IP addresses and performs IP address management, session maintenance, and optional caching. RADIUS server  136  is responsible for performing functions related to authentication, authorization, and accounting (AAA) of packet data services, and may be referred to as an AAA server. 
     Those skilled in art will appreciate that wireless network  104  may be connected to other systems, possibly including other networks, not explicitly shown in  FIG. 1 . A network will normally be transmitting at very least some sort of paging and system information on an ongoing basis, even if there is no actual packet data exchanged. Although the network consists of many parts, these parts all work together to result in certain behaviours at the wireless link. We use a Cdma2000™ network as an example for the description, but these techniques in the present application are not limited to the use of cdma2000™. 
       FIG. 2  is a detailed block diagram of a preferred mobile station  202 . Mobile station  202  is preferably a two-way communication device having at least voice and advanced data communication capabilities, including the capability to communicate with other computer systems. Depending on the functionality provided by mobile station  202 , it may be referred to as a data messaging device, a two-way pager, a cellular telephone with data messaging capabilities, a wireless Internet appliance, or a data communication device (with or without telephony capabilities). Mobile station  202  may communicate with any one of a plurality of base station transceiver systems  200  within its geographic coverage area. 
     Mobile station  202  will normally incorporate a communication subsystem  211 , which includes a receiver  212 , a transmitter  214 , and associated components, such as one or more (preferably embedded or internal) antenna elements  216  and  218 , local oscillators (LOs)  213 , and a processing module such as a digital signal processor (DSP)  220 . Communication subsystem  211  is analogous to RF transceiver circuitry  108  and antenna  110  shown in  FIG. 1 . As will be apparent to those skilled in field of communications, particular design of communication subsystem  211  depends on the communication network in which mobile station  202  is intended to operate. 
     Mobile station  202  may send and receive communication signals over the network after required network registration or activation procedures have been completed. Signals received by antenna  216  through the network are input to receiver  212 , which may perform such common receiver functions as signal amplification, frequency down conversion, filtering, channel selection, and like, and in example shown in  FIG. 2 , analog-to-digital (A/D) conversion. A/D conversion of a received signal allows more complex communication functions such as demodulation and decoding to be performed in DSP  220 . In a similar manner, signals to be transmitted are processed, including modulation and encoding, for example, by DSP  220 . These DSP-processed signals are input to transmitter  214  for digital-to-analog (D/A) conversion, frequency up conversion, filtering, amplification and transmission over communication network via antenna  218 . DSP  220  not only processes communication signals, but also provides for receiver and transmitter control. For example, the gains applied to communication signals in receiver  212  and transmitter  214  may be adaptively controlled through automatic gain control algorithms implemented in DSP  220 . 
     Network access is associated with a subscriber or user of mobile station  202 , and therefore mobile station  202  requires a memory module  262 , such as a Subscriber Identity Module or “SIM” card or a Removable User Identity Module (R-UIM), to be inserted in or connected to an interface  264  of mobile station  202  in order to operate in the network. Alternatively, flash memory  224  may be a non-volatile memory which is programmed with configuration data by a service provider so that mobile station  202  may operate in the network. Since mobile station  202  is a mobile battery-powered device, it also includes a battery interface  254  for receiving one or more rechargeable batteries  256 . Such a battery  256  provides electrical power to most if not all electrical circuitry in mobile station  202 , and battery interface  254  provides for a mechanical and electrical connection for it. The battery interface  254  is coupled to a regulator (not shown in  FIG. 2 ) which provides power V+ to all of the circuitry. 
     Mobile station  202  includes a microprocessor  238  (which is one implementation of controller  106  of  FIG. 1 ) which controls overall operation of mobile station  202 . This control includes network selection techniques of the present application. Communication functions, including at least data and voice communications, are performed through communication subsystem  211 . Microprocessor  238  also interacts with additional device subsystems such as a display  222 , a flash memory  224 , a random access memory (RAM)  226 , auxiliary input/output (I/O) subsystems  228 , an external communication port  230 , a keyboard  232 , a speaker  234 , a microphone  236 , a short-range communications subsystem  240 , and any other device subsystems generally designated at  242 . Some of the subsystems shown in  FIG. 2  perform communication-related functions, whereas other subsystems may provide “resident” or on-device functions. Notably, some subsystems, such as keyboard  232  and display  222 , for example, may be used for both communication-related functions, such as entering a text message for transmission over a communication network, and device-resident functions such as a calculator or task list. Operating system software used by microprocessor  238  is preferably stored in a persistent store such as flash memory  224 , which may alternatively be a read-only memory (ROM) or similar storage element (not shown). Those skilled in the art will appreciate that the operating system, specific device applications, or parts thereof, may be temporarily loaded into a volatile store such as RAM  226 . 
     Microprocessor  238 , in addition to its operating system functions, preferably enables execution of software applications on mobile station  202 . A predetermined set of applications which control basic device operations, including at least data and voice communication applications, will normally be installed on mobile station  202  during its manufacture. A preferred application that may be loaded onto mobile station  202  may be a personal information manager (PIM) application having the ability to organize and manage data items relating to user such as, but not limited to, e-mail, calendar events, voice mails, appointments, and task items. Naturally, one or more memory stores are available on mobile station  202  and SIM  262  to facilitate storage of PIM data items and other information. 
     The PIM application preferably has the ability to send and receive data items via the wireless network. In a preferred embodiment, PIM data items are seamlessly integrated, synchronized, and updated via the wireless network, with the mobile station user&#39;s corresponding data items stored and/or associated with a host computer system thereby creating a mirrored host computer on mobile station  202  with respect to such items. This is especially advantageous where the host computer system is the mobile station user&#39;s office computer system. Additional applications may also be loaded onto mobile station  202  through network, an auxiliary I/O subsystem  228 , communication port  230 , short-range communications subsystem  240 , or any other suitable subsystem  242 , and installed by a user in RAM  226  or preferably a non-volatile store (not shown) for execution by microprocessor  238 . Such flexibility in application installation increases the functionality of mobile station  202  and may provide enhanced on-device functions, communication-related functions, or both. For example, secure communication applications may enable electronic commerce functions and other such financial transactions to be performed using mobile station  202 . 
     In a data communication mode, a received signal such as a text message, an e-mail message, or web page download will be processed by communication subsystem  211  and input to microprocessor  238 . Microprocessor  238  will preferably further process the signal for output to display  222  or alternatively to auxiliary I/O device  228 . A user of mobile station  202  may also compose data items, such as e-mail messages, for example, using keyboard  232  in conjunction with display  222  and possibly auxiliary I/O device  228 . Keyboard  232  is preferably a complete alphanumeric keyboard and/or telephone-type keypad. These composed items may be transmitted over a communication network through communication subsystem  211 . 
     For voice communications, the overall operation of mobile station  202  is substantially similar, except that the received signals would be output to speaker  234  and signals for transmission would be generated by microphone  236 . Alternative voice or audio I/O subsystems, such as a voice message recording subsystem, may also be implemented on mobile station  202 . Although voice or audio signal output is preferably accomplished primarily through speaker  234 , display  222  may also be used to provide an indication of the identity of a calling party, duration of a voice call, or other voice call related information, as some examples. 
     Communication port  230  in  FIG. 2  is normally implemented in a personal digital assistant (PDA)-type communication device for which synchronization with a user&#39;s desktop or laptop computer is a desirable, albeit optional, component. Examples of such a port include an RS-232 port and a Universal Serial Bus (USB). Communication port  230  enables a user to set preferences through an external device or software application and extends the capabilities of mobile station  202  by providing for information or software downloads to mobile station  202  other than through a wireless communication network. The alternate download path may, for example, be used to load an encryption key onto mobile station  202  through a direct and thus reliable and trusted connection to thereby provide secure device communication. 
     Short-range communications subsystem  240  of  FIG. 2  is an additional optional component which provides for communication between mobile station  202  and different systems or devices, which need not necessarily be similar devices. For example, subsystem  240  may include an IrDA™ communication module or a Bluetooth™ communication module to provide for communication with similarly-enabled systems and devices. IrDA™ and Bluetooth™ are trademarks of Infrared Data Association and Bluetooth SIG Inc., respectively. A PDA-type communication device may also use IrDA or Bluetooth technology for synchronization with a user&#39;s desktop or laptop computer. 
     Mobile station  202  also includes one or more temperature sensors and a battery voltage sensor  290  which are used to control its operational states and communication capabilities (described later in detail in relation to  FIGS. 3-4 ). In the present embodiment, two temperature sensors are included in mobile station  202 . One temperature sensor  280  is located adjacent communication subsystem  211  and, more specifically, adjacent to a power amplifier (PA) of communication subsystem  211 , for example. Temperature sensor  280  is coupled to microprocessor  238 , which continually monitors a temperature from temperature sensor  280 . Temperature sensor  280  may be, for example, a thermistor having a resistance which varies in accordance with changes in temperature to provide a change in voltage detected at microprocessor  238 . When mobile station  202  is communicating information with use of communication subsystem  211  (e.g. with its transmitter  214  on), for example, communication subsystem  211  heats up and its temperature rises. The ambient temperature also affects the temperature of components in communication subsystem  211 . If the temperature of communication subsystem  211  is outside certain specification parameters, spurious signals would be undesirably emitted by transmitter  214  at unacceptable levels. However, mobile station  202  operates to eliminate or reduce the possibility of such occurrences as will be described later below in relation to  FIGS. 3 and 4 . 
     Note that, although only a single temperature sensor  280  is shown and described for communication subsystem  211 , a temperature sensor may be utilized for each one of multiple PAs in mobile station  202  which correspond to multiple frequency bands within which the mobile station  202  may operate (e.g. cellular band, PCS band, etc.). 
     Another temperature sensor  282  is located in battery or battery pack  256 . Temperature sensor  282  is coupled to microprocessor  238  through battery interface  254 . Temperature sensor  282  may be, for example, a thermistor which fluctuates its resistance in accordance with changes in temperature to provide a change in voltage detected at microprocessor  238 . When mobile station  202  is communicating information with use of communication subsystem  211  (e.g. with its transmitter  214  on), for example, battery  256  heats up and its temperature rises. The ambient temperature also affects the temperature of battery  256 . If the temperature of battery  256  is outside certain specification parameters for too long of a time period, battery  256  may experience permanent damage and require replacement or could even explode. However, mobile station  202  operates to eliminate or reduce the possibility of such occurrences as will be described later below in relation to  FIGS. 3 and 4 . 
     Battery voltage sensor  290  is also coupled to microprocessor  238  through battery interface  254 . Battery voltage sensor  290  may be implemented using an analog-to-digital (A/D) converter, for example. Battery voltage sensor  290  is used to continually measure the voltage of battery  256 , so that microprocessor  238  may appropriately control communication subsystem  211 . In particular, when the battery voltage becomes low, mobile station  202  operates to limit the use of communication subsystem  211  to extend the life of battery  256  as will be described later below. 
       FIG. 3  is a state diagram  300  which illustrates various operating states of a mobile communication device such as the mobile station shown and described in relation to  FIGS. 1 and 2 . More particularly, state diagram  300  illustrates various communication states which are responsive to different operating conditions of the mobile station. In the present embodiment of  FIG. 3 , the different communication states of the mobile station are responsive to different temperature conditions of the mobile station. The changes in communication states, however, could be responsive to other changing operating conditions of the mobile station, such as low battery conditions or automatic location-based power down conditions (e.g. automatic airplane power down). 
     As shown in state diagram  300 , the communication states of the mobile station include a full communication state  302 , a limited communication state  304 , an emergency-only text communication state  306 , and an off state  308 . In general, the mobile station continually monitors a reading from a sensor and selects one of the communication states  302 ,  304 ,  306 , and  308  based on the reading. In particular in  FIG. 3 , the mobile station monitors an operating temperature T based on a reading from a temperature sensor and selects one of the communication states  302 ,  304 ,  306 , and  308  based on temperature. Several predetermined temperature thresholds are known by and stored in memory of the mobile station. In this exemplary embodiment, six (6) different temperature thresholds T 1 , T 2 , T 3 , T 4 , T 5 , and T 6  are known by and stored in the mobile station, where T 1 &lt;T 2 &lt;T 3 &lt;T 4 &lt;T 5 &lt;T 6 . These six different temperature thresholds are associated with different operating temperature ranges which may include a normal operating temperature range T 3 -T 4 ; one or more poor operating temperature ranges T 2 -T 3  and T 4 -T 5  (lower and upper, respectively); one or more very poor operating temperature ranges T 1 -T 2  and T 5 -T 6  (lower and upper, respectively); and one or more extremely poor operating temperature ranges less than T 1  or greater than T 6 . 
     Preferably, the mobile station selects one of the communication states  302 ,  304 ,  306 , and  308  based on readings from more than one sensor. For example, the mobile station may select one of the communication states based on both the temperature of the RF PA and the temperature of the battery. As another example, the mobile station may select one of the communication states based on both the temperature of the RF PA and the battery voltage of the battery. Using this type of approach, each sensor has a corresponding set of predetermined thresholds which are stored in memory of the mobile station. Accordingly, a communication state of the mobile station is determined and selected based on readings and decisions from all of relevant sensors. For example, the mobile station may select the most limiting communication state associated with any one of the sensors as the current communication state. 
     For clarity, state diagram  300  of  FIG. 3  will be described where a single operating temperature (which may be viewed as a composite reading from all sensors) drives the selection of a communication state. Under normal operating circumstances, the mobile station identifies the operating temperature T to be within a predetermined temperature range of T 3 ≦T≦T 4 . T 3  may be about −10° C. and T 4  may be about 60° C., for example. In this case, the mobile station will operate in full communication state  302 . In full communication state  302 , the mobile station allows its full communication capabilities for the end user. The mobile station permits two-way voice calls and data packet communication sessions (e.g. e-mail message and Internet data communications). The wireless transceiver of the mobile station is kept operational, although the transmitter and receiver may be powered down intermittently in sleep modes when necessary to conserve power as is conventional. The coding and modulation methods utilized by the wireless transceiver are not limited in any way in state  302 . Preferably, a visual indication of this communication state is provided in the visual display of the mobile station (e.g. “FULL”). 
     In poor temperature conditions, the mobile station identifies the operating temperature T to be within one of the poor operating temperature ranges, where T 2 ≦T&lt;T 3  or T 4 &lt;T≦T 5 . T 2  may be about −20° C. and T 5  may be about 80° C., for example. If the operating temperature T is poor, spurious signals may be undesirably emitted by the transmitter at unacceptable levels when transmitting at the allowed maximum transmit power level in normal operating circumstances. Also, the battery may experience permanent damage and require replacement. Thus, if T 2 ≦T&lt;T 3  or T 4 &lt;T≦T 5 , the mobile station controls itself to operate in limited communication state  304 . In limited communication state  304 , the mobile station allows only limited communication capabilities for the end user. The transmitter is normally powered off while the receiver is kept operational (albeit powered down intermittently in sleep modes to conserve power as is conventional). Alternatively, the transmitter and receiver are both powered off. In limited communication state  304 , the mobile station does not permit any non-emergency communications such as non-emergency voice calls, non-emergency data service (e.g. communicating any normal e-mail message, Internet browsing, etc.), and over-the-air service provisioning. 
     In limited communication state  304 , however, the mobile station does permit the placement of emergency two-way voice calls (e.g. 911 voice call) and permits any emergency data packet communication (e.g. emergency message or Internet data communication). If an emergency communication request is received at the user interface, the transmitter (and receiver where applicable) is powered on and the maximum transmit power is limited to a lower power level to reduce the likelihood of unacceptable spurious emissions. Also, the coding and modulation methods of the wireless transceiver may be limited for the same reasons. Preferably, after a mobile-initiated emergency communication, the mobile station invokes an emergency callback period during which mobile station enables and allows network-initiated position location services as well as incoming voice calls. Typically, a mobile station enters an emergency callback period lasting for five (5) minutes after an emergency call is terminated. This allows a Public Safety Answer Point (PSAP) the ability to call back and/or locate the user with use of technology such as Assisted Global Positioning System (A-GPS). Preferably, a visual indication of this communication state is provided in the visual display of the mobile station (e.g. “LIMITED” or “EMERGENCY ONLY”). 
     Under more adverse temperature conditions, the mobile station identifies the operating temperature T to be within one of the very poor operating temperature ranges, where T 1 ≦T&lt;T 2  or T 5 &lt;T≦T 6 . T 1  may be about −25° C. and T 6  may be about 100° C., for example. If the operating temperature T is at such a level, spurious signals may be undesirably emitted by the transmitter at unacceptable levels when transmitting at the allowed maximum transmit power level in normal operating circumstances. Also, the battery may experience permanent damage and require replacement. Furthermore, the receiver performance may be degraded. Thus, if T 1 ≦T&lt;T 2  or T 5 &lt;T≦T 6 , the mobile station controls itself to operate in emergency-only text communication state  306 . In emergency-only text communication state  306 , the transmitter and the receiver are kept powered down (i.e. completely powered off, not merely in a sleep mode of operation). The mobile station does not permit any services including non-emergency or emergency (e.g. 911) two-way voice calls, or non-emergency data packet transmissions for end-user communication (e.g. ordinary e-mail message and Internet data communications), and over-the-air service provisioning. The mobile station also does not permit the reception of ordinary data packet communications (e.g. ordinary e-mail messages). In emergency-only text communication state  306 , the mobile station only permits a mobile-initiated communication of text-based emergency messages. Preferably, a visual indication of this communication state may be provided in the visual display of the mobile station (e.g. “EMERGENCY ONLY TEXT”), assuming that the visual display can operate under such conditions. 
     These emergency text messages may be in the form of a short message service (SMS) message and/or an e-mail message, for example, which are communicated to some form of a Public-Safety Answering Point (PSAP) supporting messages. Preferably, the text-based emergency message is a predefined, prestored emergency text message in the mobile station (e.g. “EMERGENCY—PLEASE HELP”). In general, the sending of the emergency text message is the only time that the transceiver is powered on in state  306 . The maximum transmit power is preferably limited at an even lower level to reduce the likelihood that no unacceptable spurious emissions exist. Also preferably, the emergency message is transmitted at a low data rate which requests a lower transmit power to achieve a given reliability of communication. Further, the coding and modulation methods of the wireless transceiver may be limited if necessary. The information may be sent over a control channel (e.g. an access channel) which eliminates the need of setting up a traffic channel. For example, the emergency text message may be in the form of an emergency SMS message transmitted over an access channel. The emergency message may or may not be accompanied by user-identifying information and/or location information (e.g. pilot phase information). Preferably, such information is included in the emergency message. An audible indication may be provided at the user interface to confirm that the emergency text message has been successfully transmitted and/or received (especially important where the visual display of the mobile station may not be operable under such conditions). 
     Under even more adverse operating conditions, the mobile station identifies the operating temperature T to be below temperature T 1  or above temperature T 6 . If the operating temperature T is at such a level, spurious signals may be undesirably emitted by the transmitter at unacceptable levels or the battery may experience permanent damage and require replacement or could even explode. In this case, the mobile station controls itself to power down to the off state  308 . In off state  308 , the mobile station is completely shut down and no communication capabilities are provided for the end user. Not even emergency communications can be provided by the mobile station in off state  308 . 
     Thus, when a communication request for communicating information is received through a user interface (e.g. keypad, keyboard, or touch screen display) of the mobile station, the mobile station will inhibit or allow the communication request depending on which communication state it is operating in. In the limited communication state, for example, the mobile station will inhibit a non-emergency communication but allow an emergency communication. 
       FIG. 4  is a flowchart which describes a method of limiting communication capabilities in a mobile communication device such as the mobile station described in relation to  FIGS. 1 and 2 . The communication states and temperatures/temperature ranges correspond to those described in relation to state diagram  300  of  FIG. 3 . A computer program product may include computer instructions stored on a computer storage medium (memory of the mobile station, a floppy disk or CD-ROM) which are written in accordance with the described logic. 
     Beginning at a start block  402  of  FIG. 4 , the mobile station detects whether its operating temperature T is within temperature range T 3 -T 4  (step  404 ). If so, the mobile station operates in its full communication state (step  406 ). If the operating temperature T is not within temperature range T 3 -T 4 , the mobile station detects whether the operating temperature T is within temperature range T 2 -T 3  or T 4 -T 5  (step  408 ). If so, the mobile station operates in its limited communication state (step  410 ). If the operating temperature T is not within temperature range T 2 -T 3  or T 4 -T 5 , the mobile station detects whether its operating temperature T is within temperature range T 1 -T 2  or T 5 -T 6  (step  412 ). If so, the mobile station operates in its emergency-only communication state (step  414 ). If the operating temperature T is not within T 1 -T 2  or T 5 -T 6 , the mobile station detects whether its operating temperature T is less than T 1  or greater than T 6  (step  416 ). If so, the mobile station powers itself down completely (step  418 ). The mobile station will remain powered down from step  418  until the end user powers it back up and the adverse condition is gone. Upon power up, the mobile station starts again at start block  402  and may operate to follow the previous decision to obtain the device state. For example, if the mobile station is determined to be in OFF state again, the mobile station powers itself off after an audible or visual indication to the user; if the adverse condition is gone, however, the mobile station will remain in a different state corresponding to current conditions. 
     Although  FIGS. 3 and 4  are primarily directed to limiting communication capabilities based on temperature, the techniques apply to limiting communication capabilities based on low battery voltage in the same way (or limiting communication capabilities based on the combined use of temperature(s) and low battery voltage). 
     Final Comments. Methods and apparatus for limiting communication capabilities in mobile communication devices have been described. In one illustrative example, a predetermined condition such as an unsatisfactory temperature or a low battery voltage is detected at the mobile communication device. At this time, a communication request for communicating information through a wireless communication network is received through a user interface. If the communication request is for a non-emergency communication, the non-emergency communication is inhibited during the existence of the predetermined condition. If the communication request is for an emergency communication, however, the emergency communication is allowed despite the existence of the predetermined condition. The emergency communication may be a “911” voice call or an emergency message. The maximum allowed transmit power may be limited to a certain level to reduce the likelihood that unacceptable spurious emissions exist. The coding and modulation methods may also be limited to a subset of that which the mobile station would otherwise support. 
     The above-described embodiments of the present application are intended to be examples only. Those of skill in the art may effect alterations, modifications and variations to the particular embodiments without departing from the scope of the application. For example, instead of using temperature-based conditions, low battery conditions or automatic location-based power down conditions (e.g. automatic airplane power down) may be utilized. The invention described herein in the recited claims intends to cover and embrace all suitable changes in technology.

Technology Classification (CPC): 8