Abstract:
An apparatus including a wireless local area network transceiver, a wireless wide area network transceiver, and a portable power source. The wireless local area network transceiver is configured to wirelessly communicate with a client station using a wireless local area network protocol. The wireless wide area network transceiver is configured to wirelessly communicate with a base station. The portable power source has a state of charge and is configured to provide power to the wireless local area network transceiver and the wireless wide area network transceiver. The wireless wide area network transceiver is configured to suspend wireless communication with the base station in response to no packets of data having been received at the wireless wide area network transceiver from the base station for more than a predetermined period of time. The predetermined period of time is adjusted based on the state of charge of the portable power source.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This present disclosure is a continuation of U.S. application Ser. No. 13/269,766, filed Oct. 10, 2011, which is a continuation of U.S. application Ser. No. 12/711,577, filed on Feb. 24, 2010, which is a continuation of U.S. application Ser. No. 11/295,106 (now U.S. Pat. No. 7,672,695), filed Dec. 6, 2005. The disclosures of these applications are hereby incorporated by reference in their entireties. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to access points for networks, and more particularly to portable access points. 
     BACKGROUND OF THE INVENTION 
     Referring now to  FIG. 1 , a functional block diagram of a wireless router  100  according to the prior art is presented. The wireless router  100  includes a wireless LAN (Local Area Network) transceiver  102 , which uses IEEE 802.11 to communicate with multiple wireless client devices (not shown). The wireless LAN transceiver  102  communicates with a routing module  104  and with a processor  106 . The processor  106  communicates with system storage  108  and with a WAN (Wide Area Network) Ethernet port  110 , which provides an RJ-45 connector for connecting to a cable modem, DSL (Digital Subscriber Line) modem, or any other suitable WAN connection. The wireless router  100  is powered via a power cable socket  112  that receives power from an electrical outlet, usually through a transformer (not shown). 
     The routing module  104  also communicates with a firewall  114  and a DHCP (Dynamic Host Configuration Protocol) server  116 . The routing module  104  communicates packets between the WAN Ethernet port  110  and the wireless LAN transceiver  102 , subject to firewall  114  restrictions. The firewall  114  protects against malicious traffic, and may also allow for parental control. The routing module  104  can also send packets between wireless devices communicating with the wireless LAN transceiver  102 . The DHCP server  116  answers requests received by the wireless LAN transceiver  102  for IP (Internet Protocol) addresses. These IP addresses are dynamically assigned to wireless devices as they attempt to connect to the wireless router  100 . 
     The firewall  114  may also provide NAT (Network Address Translation) capability for sharing a common IP address among the multiple wireless devices communicating with the wireless LAN transceiver  102 . The processor  106  controls operation of the wireless LAN transceiver  102 , the routing module  104 , system storage  108 , the WAN Ethernet port  110 , the firewall  114 , and the DHCP server  116 . The processor  106  retrieves instructions from system storage  108 , and may also store operating parameters in system storage  108 . The processor  106  may also function as a web server to provide a convenient interface to client devices for updating various settings of the wireless router  100 . The firewall  114  and DHCP server  116  may be implemented as functions of the processor  106 . 
     SUMMARY OF THE INVENTION 
     A portable access point comprises a wireless LAN transceiver that is capable of establishing a plurality of Ethernet wireless links with a plurality of wireless client devices, respectively. A wireless WAN transceiver establishes an Ethernet data connection with an Internet Service Provider (ISP), receives and forwards Ethernet data packets from at least one of said wireless client devices to said ISP and receives and forwards Ethernet data packets from said ISP to said one of said wireless client devices. A routing device routes Ethernet data packets between said wireless LAN transceiver and said wireless WAN transceiver. A control module controls operation of said wireless LAN transceiver and said wireless WAN transceiver. A first storage device stores operating system and application instructions for said control module. 
     In other features, a charging connection provides power from the power source to an external battery-powered device. The wireless LAN transceiver includes a sleep mode that stops transmission and waits for a resume signal to be received, and wherein the control module places the wireless LAN transceiver in the sleep mode to conserve power. The control module places the wireless LAN transceiver in the sleep mode when packets have not been received at the wireless LAN transceiver for a first period of time. 
     In further features, the control module monitors a state of charge of the power source, the first period of time varying in accordance with the state of charge. The control module monitors a state of the power source to determine a power saving feature level. A second storage device is used for storing at least one of backup data and media information. The second storage device includes a universal file system to allow the second storage device to appear as a removable storage device to the wireless devices. 
     In still other features, the wireless WAN transceiver includes a Bluetooth transceiver operable to communicate with a Bluetooth mobile phone that can establish a data service with the ISP. The wireless WAN transceiver includes a digital cellular transceiver operable to communicate with the ISP via a data service of a mobile telephony service provider. A belt clip permits wearing of the portable access point. A firewall protects the wireless devices from malicious activity. The firewall provides Network Address Translation (NAT) for the wireless devices. A DHCP server leases Internet Protocol (IP) addresses to the wireless devices. 
     In other features, an expansion port is operable for connecting to a headset. The expansion port is operable for connecting to physiological sensors. The physiological sensors include at least one of a thermometer, a blood glucose meter, a blood pressure monitor, a stethoscope, a pedometer, an ECG recorder, and an EEG recorder. The expansion port includes at least one analog to digital converter for converting analog physiological data to a digital format. The expansion port includes at least one preamplifier to boost a signal level from one of the physiological sensors. 
     In further features, a Global Positioning System receiver determines a physical location of the portable access point, wherein the control module is operable to transmit the physical location to a remote site when an alarm condition is detected. A display displays information pertaining to collected data from the physiological sensors. An input device accepts input from the input device to determine when to sample data from the physiological sensors. A web server module provides a secure web interface to authorized users for accessing collected data from the physiological sensors. 
     In still other features, the control module receives media information, and at least one of records and streams the media information. Media information is received from the satellite radio tuner and the AM/FM tuner. An audio port is operable to connect to at least one of headphones and a stereo system. The portable access point also includes a microphone, a speaker, an input device that receives information including telephone numbers, and a display for displaying the telephone numbers and call status. Wired ports communicate with wired network devices. 
     A portable access point comprises providing mobile access point that supports a wireless local area network (LAN) and a wide area network; selectively establishing a plurality of Ethernet wireless links with a plurality of remote wireless client devices, respectively; selectively establishing an Ethernet data connection with a remote Internet Service Provider (ISP); receiving and forwarding Ethernet data packets from at least one of said wireless client devices to said ISP; receiving and forwarding Ethernet data packets from said ISP to said one of said wireless client devices; routing packets between said wireless LAN and said wireless WAN; controlling operation of said wireless LAN and said wireless WAN; and storing operating system and application instructions. 
     In other features, the method further comprises providing power to an external battery-powered device. The method further comprises operating in a sleep mode until a resume signal is received from one of the plurality of wireless devices. 
     In further features, operating in sleep mode is performed when packets have not been received from the plurality of wireless devices for a first period of time. Operating in sleep mode includes monitoring a state of charge and varying the first period of time in accordance with the state of charge. The method further comprises monitoring a state of charge to determine a power saving feature level. The method further comprises storing at least one of backup data and media information. 
     In still other features, the method wherein the establishing includes communicating with a mobile phone capable of establishing a data service with the ISP. Establishing includes communicating directly with a data service of a mobile telephony service provider. The method further comprises protecting the wireless devices from malicious activity. The method further comprises providing Network Address Translation (NAT) to the wireless devices. The method further comprises providing IP address leases to the wireless devices. 
     In still further features, the method further comprises receiving data from physiological sensors. The physiological sensors include at least one of a thermometer, a blood glucose meter, a blood pressure monitor, a stethoscope, a pedometer, an ECG recorder, and an EEG recorder. The method further comprises converting analog physiological data into a digital format. The method further comprises boosting a signal level from one of the physiological sensors. 
     In other features, the method further comprises determining a physical location and transmitting the physical location to a remote site when an alarm condition is detected. The method further comprises displaying information pertaining to collected data from the physiological sensors. The method further comprises accepting input to determine when to sample data from the physiological sensors. The method further comprises providing a secure web interface to authorized users for accessing collected data from the physiological sensors. 
     In further features, the method further comprises receiving media information, and at least one of recording and streaming the media information. Receiving includes receiving media information from a satellite radio tuner. Receiving includes receiving media information from an AM/FM tuner. 
     A portable access point comprises wireless LAN transceiving means for establishing a plurality of Ethernet wireless links with a plurality of wireless client devices, respectively. Wireless WAN transceiving means establishes an Ethernet data connection with an Internet Service Provider (ISP), receives and forwards Ethernet data packets from at least one of said wireless client devices to said ISP and receives and forwards Ethernet data packets from said ISP to said one of said wireless client devices. Routing means routes Ethernet data packets between said wireless LAN transceiving means and said wireless WAN transceiving means. Control means controls operation of said wireless LAN transceiving means and said wireless WAN transceiving means. Storing means stores operating system and application instructions for said control means. 
     In other features, charging means provides power from the charge storage means to an external battery-powered device. The wireless LAN transceiving means includes a sleep mode that stops transmission and waits for a resume signal to be received, and wherein the control means places the wireless LAN transceiving means in the sleep mode to conserve power. The control means places the wireless LAN transceiving means in the sleep mode when packets have not been received at the wireless LAN transceiving means for a first period of time. 
     In further features, the control means monitors a state of charge of the charge storage means, the first period of time varying in accordance with the state of charge. The control means monitors a state of the charge storage means to determine a power saving feature level. Second storage means stores at least one of backup data and media information. The second storage means includes universal file means for allowing the second storage means to appear as a removable device to the wireless devices. 
     In still other features, the wireless WAN transceiving means includes Bluetooth transceiving means for communicating with Bluetooth mobile means for establishing a data service with the ISP. The wireless WAN transceiving means includes digital cellular means for communicating with the ISP via a data service of a mobile telephony service provider. Belt clip means allows wearing of the portable access point. Firewall means protects the wireless devices from malicious activity. The firewall means provides Network Address Translation (NAT) for the wireless devices. DHCP means leases Internet Protocol (IP) addresses to the wireless devices. 
     In still further features, expansion port means connects to a stereo system. Expansion port means connects to a headset. Expansion port means receives data from physiological sensors. The physiological sensors include at least one of a thermometer, a blood glucose meter, a blood pressure monitor, a stethoscope, a pedometer, an ECG recorder, and an EEG recorder. The expansion port means includes at least one analog to digital converting means for converting analog physiological data to a digital format. The expansion port means includes at least one preamplifying means for boosting a signal level from one of the physiological sensors. 
     In other features, Global Positioning System means determines a physical location of the portable access point, wherein the control means is operable to transmit the physical location to a remote site when an alarm condition is detected. Display means displays information pertaining to collected data from the physiological sensors on the display means. Input means accepts input to determine when to sample data from the physiological sensors. Web server means provides a secure web interface to authorized users for accessing collected data from the physiological sensors. 
     In further features, the control means receives media information, and at least one of records and streams the media information. Satellite radio tuning means receives satellite radio media information. AM/FM tuning means receives AM/FM media information. Audio port means connects to at least one of headphones and a stereo system. The portable access point also includes microphonic means for receiving audio information, speaker means for producing audio information, input device means for receiving user information including telephone numbers, and display means for displaying the telephone numbers and call status. Wired LAN means communicates with wired network devices. 
     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
         FIG. 1  is a functional block diagram of a wireless router according to the prior art; 
         FIG. 2  is a functional block diagram of an exemplary system according to the principles of the present invention; 
         FIG. 3  is a functional block diagram of an alternative exemplary system according to the principles of the present invention; 
         FIG. 4  is a functional block diagram of an exemplary implementation of a low-power portable access point according to the principles of the present invention; 
         FIG. 5  is a functional block diagram of an exemplary implementation of a more richly featured portable access point according to the principles of the present invention; and 
         FIG. 6  is a functional block diagram of an exemplary portable access point tailored to physiological monitoring applications according to the principles of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. For purposes of clarity, the same reference numbers will be used in the drawings to identify similar elements. As used herein, the term module refers to an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality. As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A or B or C), using a non-exclusive logical or. It should be understood that steps within a method may be executed in different order without altering the principles of the present invention. 
     Referring now to  FIG. 2 , a functional block diagram of an exemplary system according to the principles of the present invention is presented. A portable access point  202  is shown communicating with various client devices  204 . Device  204 - 1  may be a personal computer, device  204 - 2  may be a printer device, device  204 - 3  may be a digital camera, and device  204 - 4  may be a laptop computer. Additional or fewer devices may be connected to the portable access point  202 , and may be of many different types. The portable access point  202  communicates with the Internet, represented graphically at  210 , via an Internet Service Provider. The portable access point  202  may communicate with the Internet  210  via GPRS (General Packet Radio Service), CDMA2000 (indicating a 3G service using Code Division Multiple Access), UMTS (Universal Mobile Telecommunications System), WiMax or I.E.E.E. 802.16, which is hereby incorporated by reference in its entirety, Evolution Data Optimized (EVDO) broadband wireless access based on 3G, or any other suitable wide area network mechanism. 
     Alternately, the portable access point  202  may communicate with the Internet  210  via the scheme depicted in  FIG. 3 . In  FIG. 3 , the portable access point  202  communicates with a mobile phone  220  via a short-range wireless protocol such as Bluetooth. Alternately, a physical connection could be established between the mobile phone  220  and the portable access point  202 . The mobile phone  220  communicates with a wireless service provider  222 , which in turn communicates with the Internet  210 . The portable access point  202  uses the mobile phone  220  as a data service conduit to the wireless service provider  222 . 
     Referring again to  FIG. 2 , the portable access point  202  allows the wireless devices  204  to communicate with each other, and to communicate with hosts on the Internet  210 . The portable access point  202  may provide IP addresses via DHCP to the wireless devices  204 . The portable access point  202  may also include NAT capability to allow an IP address visible to the Internet  210  to be shared by the wireless devices  204 . The portable access point may also include a firewall to protect the devices  204  from malicious activity, and may include a web server for easy configuration of the portable access point  202 . 
     The portable access point  202  may further include storage such that media and/or data information can be stored in the portable access point  202 . This information may include pictures from the digital camera  204 - 3  or backup files from the laptop computer  204 - 4 . The information may also include recorded or downloaded audio/video content and/or physiological information, discussed in further detail below. The portable access point  202  is powered by a portable power source, such as a battery. Solar power or a hand crank may also provide power to the portable access point  202 . The portable access point  202  may be configured so as to be worn on a user&#39;s belt, placed in a briefcase, or located in a purse. 
     Referring now to  FIG. 4 , a functional block diagram of an exemplary implementation of a low-power portable access point  300  according to the principles of the present invention is presented. The portable access point  300  includes a processor  302  that communicates with system storage  304 . The system storage  304  includes instructions for the processor  302 , and also includes operating parameters. Based on instructions from system storage  304 , which may include an operating system and application programs, the processor  302  directs operation of a routing module  308 , a wireless LAN transceiver  310 , a DHCP server  312 , a firewall  314 , a wireless WAN transceiver  316 , and a battery pack  320 . The routing module  308  communicates with the DHCP server  312 , the firewall  314 , the wireless WAN transceiver  316 , the wireless LAN transceiver  310 , and the processor  302 . 
     The wireless LAN transceiver  310  can communicate with multiple wireless devices (not shown) via a wireless networking protocol, such as IEEE 802.11, proprietary extensions of IEEE 802.11, and/or other suitable wireless networking protocols. The wireless WAN transceiver  316  establishes a connection to the Internet (not shown) as discussed in  FIGS. 2 and 3 . In the implementation of  FIG. 2 , the wireless WAN transceiver  316  may implement a suitable wireless packet data protocol such as GPRS, CDMA2000, and/or UMTS. In the implementation of  FIG. 3 , the wireless WAN transceiver  316  may implement a Bluetooth (or other suitable short range wireless network) protocol to communicate with a data-enabled mobile phone. Alternately, the wireless WAN transceiver  316  may be replaced with a wired connection to the mobile phone. 
     The routing module  308 , as controlled by the processor  302 , allows packets to be communicated among and between wireless devices connected to the wireless LAN transceiver  310  and the Internet via the wireless WAN transceiver  316 . Additionally, the routing module  308  may route packets to and from an optional wired network connection (not shown), such as Ethernet. The DHCP server  312  assigns IP addresses to wireless devices requesting such addresses through the wireless LAN transceiver  310 . The processor  302  may also be capable of requesting a DHCP lease from the ISP (Internet Service Provider) via the wireless WAN transceiver  316 . The routing module  308  communicates with the DHCP server  312 , the firewall  314 , the wireless WAN transceiver  316 , the wireless LAN transceiver  310 , and the processor  302 . 
     The firewall  314  protects wireless devices connected to the wireless LAN transceiver  310  from malicious activity, and may also filter malicious activity originating from the wireless devices. The firewall  314  may implement other functions such as parental controls, intrusion detection, MAC (Media Access Control) filtering, URL (Uniform Resource Locator) filtering, time/date restrictions, and IP address filtering. The firewall  314  may further offer Network Address Translation (NAT) capability to allow the wireless devices to share a single Internet-visible IP address. The portable access point  300  may be configured to attach to a user&#39;s belt via a belt clip  330 . An optional charging connection  332  may be adjacent to, or integrated with, the belt clip  330 . The charging connection  332  allows another device to be charged from the battery pack  320 . This device may be a mobile telephone, a PDA, or any other battery-powered device. 
     The processor  302  communicates with a universal file system  306 , which in turn communicates with a storage device  307 . The universal file system  306  allows the portable access point  300  to be connected to any wired or wireless client device (e.g., desktop or laptop computer) running any major operating system (e.g., Windows, MacOS, Linux. OpenBSD, etc.). The universal file system  306  can make the storage device  307  appear as a removable storage device to the client operating system. The user can then easily transfer multimedia files (data/audio/video) between the portable access point  300  and the remote device via standard file transfer operations such as drag-and-drop. 
     The battery pack  320  communicates with a power input  322 , to which a user of the portable access point  300  can connect a power source to charge the battery pack  320 . The processor  302  may direct charging of the battery pack  320 , or the battery pack  320  may have built-in circuitry that controls its charging. The processor  302  may also be able to monitor the charge remaining in the battery pack  320  and/or modulate its output voltage. The battery pack  320  provides power to the modules within the portable access point  300 . The battery pack  320  may operate in conjunction with buck or boost converters (DC to DC) to provide various voltages to different modules. The power input  322  may accept the output of a transformer, or may accept mains voltages (such as 125V 60 Hz AC) so that an outboard transformer does not need to be carried. 
     The processor  302  controls power consumption to maximize the operating time from the battery pack  320 . The processor  302  may monitor a state of the battery pack  320  to determine how aggressively to implement power saving features. One such feature is to either power down or place a module in a sleep mode. This decision may be made based on the length of time since the module was last used. The length of time may vary in accordance with the state of charge of the battery pack  320 ; i.e., when the battery pack  320  has less charge, a module is powered down after a shorter period of time. 
     For instance, the processor  302  may power down the wireless WAN transceiver  316  when packets have not been communicated to the Internet for a period of time. If incoming connections from the Internet are expected, the wireless WAN transceiver  316  may also support a sleep mode whereby the wireless WAN transceiver  316  awaits a wake signal from the WAN. Alternately, the processor may power down the wireless WAN transceiver  316  when the firewall  314  determines there are no open TCP (Transmission Control Protocol) connections between the wireless devices and the Internet. 
     The processor  302  may also place the wireless LAN transceiver  310  in sleep mode when packets have not been received at the wireless LAN transceiver for a period of time. The wireless LAN transceiver  310  may be in a sleep mode until it receives a wake-up signal from a wireless device. In sleep mode, the wireless LAN transceiver  310  does not need to perform any transmission or decoding; only the receiver must be powered. 
     If the system storage module  304  is not being used, it can be directed to go into a sleep mode where it draws only enough power to maintain its contents. A storage technology such as flash RAM would require no power to maintain its state. The DHCP server  312  and firewall  314  may be implemented as functions of the processor  302 , and the processor  302  may cease executing these functions to conserve power. The processor  302  may reduce its operating frequency, or may itself enter into a sleep mode. In such a sleep mode, the processor  302  would wait for a wake signal to be received from the wireless LAN transceiver  310 . Additionally the portable access point  300  may have an on/off switch to allow all functions to be turned off to save power. 
     Referring now to  FIG. 5 , a functional block diagram of an exemplary implementation of a more richly featured portable access point  400  according to the principles of the present invention is presented. In this example, portable access point  400  includes mobile phone capability, which uses a display  402  to communicate information to a user, an input device  404  to receive information such as phone numbers from the user, a speaker  406  to provide audio information to the user, and a microphone  408  to receive audio information, such as the user&#39;s voice. A processor  410  controls the display  402 , the input device  404 , the speaker  406 , and the microphone  408 , using an operating system and applications retrieved from a system storage module  414 . 
     The display  402  may include a LCD (Liquid Crystal Display) or LED (Light Emitting Diode) display, may be color, and may be capable of full-motion video. The display  402  may display dialed telephone numbers and/or call status. The input device  404  may include buttons, a touchpad, scroll wheels, and/or a touch screen. The speaker  406  may include a DAC (Digital to Analog Converter) and/or an amplifier. The microphone  408  may include an ADC (Analog to Digital converter) and/or an amplifier. 
     The processor  410  may also communicate information to the user via a set of indicators  416 . These indicators may display the status of a wireless LAN transceiver  418  or a wireless WAN transceiver  420 . The wireless LAN transceiver  418  is capable of communicating with a plurality of wireless devices and may attach to an external antenna  422 , which may or may not be removable. The wireless WAN transceiver  420  communicates with a mobile telephone service provider that offers data service and may attach to an external antenna  424 , which may or may not be removable. A routing module  426  allows packets to be directed between and among devices communicating with the wireless LAN transceiver  418  and the wireless WAN transceiver  420 . The routing module  426  may also route to one or more wired ports  428  for connecting to devices with a wired LAN capability, such as Ethernet (IEEE 802.3). 
     A DHCP server  440  and a firewall  442  communicate with the routing module  426 . The DHCP server  440  provides IP addresses (in the form of a DHCP lease) to wireless devices connecting to the wireless LAN transceiver  418  or to devices connecting to the wired ports  428 . The firewall  442  filters packets and protects the wired and wireless devices from malicious activity. The processor  410  communicates with a storage device  444  that is capable of storing media information and/or user data. The media information may have originated from a variety of sources, such as on-board recording, or uploading from a user device such as a computer or media player. This content may be downloaded to wireless devices, or provided as streaming content by the processor  410 . In addition, the processor  410  may provide such content to the display  402 , the speaker  406 , or an audio port  446 . The processor accesses the storage device  444  via a universal file system module  445 , as described above with respect to  FIG. 4 . 
     The audio port  446  may allow the connection of headphones or may allow connection of the portable access point  400  to a stereo system. The portable access point  400  may also include an AM/FM tuner  448  and/or a satellite radio tuner  450 , either or both of which may utilize external antennas, represented as  452  and  454 , respectively. The processor  410  directs the tuning of the AM/FM and satellite radio tuners  448  and  450 , and may stream their media to wireless devices via the wireless LAN transceiver  418  or may store their content in the storage device  444  for later upload or playback. 
     An expansion port  460  allows the portable access point  400  to communicate with additional devices, such as a headset, an automobile phone connection, or physiological sensors as discussed below. A battery pack  470  provides power to the portable access point  400 . The battery pack  470  can be charged by a power cord connected from a mains receptacle to a charging connection  472 . The charging connection  472  may receive a DC voltage that is appropriate for charging the battery pack  470 , or may have to transform incoming AC or DC into an appropriate DC voltage for the battery pack  470 . 
     Referring now to  FIG. 6 , a functional block diagram of an exemplary portable access point  500  tailored to physiological monitoring applications according to the principles of the present invention is presented. The portable access point  500  includes a processor  502 , system storage  504 , a routing module  506 , a wireless LAN transceiver  508 , a DHCP server  510 , a firewall  512 , a wireless WAN transceiver  514 , a display  516 , an input device  518 , a storage device  520 , indicators  522 , a battery pack  524 , a charging connection  526 , and optional antennas  530  and  532 , all of which operate similarly to modules described above with respect to  FIG. 5 . In addition, the storage device  520  may incorporate a universal file system, described above with respect to  FIG. 4 . 
     The portable access point  500  contains an expansion port  534  which is adapted to be connected to various physiological sensors and recorders  550 . These sensors can include a thermometer  550 - 1 , a blood glucose meter  550 - 2 , a blood pressure monitor  550 - 3 , a stethoscope  550 - 4 , a pedometer  550 - 5 , an ECG (Electrocardiogram) recorder  550 - 6 , and an EEG (Electroencephalogram) recorder  550 - 7 . Many other types of physiological sensors can be connected, including but not limited to, mass sensors (such as digital scales), pulse oximeters (for measuring oxygenated hemoglobin proportion in blood), spirometers (for measuring air capacity of the lungs), and/or sensors for measuring international normalized ratio of prothrombin time (PT/INR). 
     These physiological sensors provide physiological data to the expansion port  534 , which is optionally processed by the processor  502  and stored in the storage device  520 . This information can be retrieved by a wireless device connected to the wireless LAN transceiver  508 , or may be available through the Internet via the wireless WAN transceiver  514 . The expansion port  534  may include ADCs to convert analog data from sensors into digital data. In addition, the expansion port  534  may include preamplifiers to boost the amplitude of incoming analog signals and/or level shifters to receive digital signals from a wide variety of digital logic families. 
     Physiological sensors  550  may alternately communicate with the wireless LAN transceiver  508  if they have wireless capability. The input device  518  may allow users to, for example, enter how often certain readings are to be taken or identify the various sensors connected to the expansion port  534 . Data being recorded, data that has previously been recorded, information pertaining to when data should be uploaded, and interpretations of readings can be conveyed to the user via the display  516 . Additionally, an optional secure web server allows physiological data to be accessed remotely, such as by clinician or hospital staff. 
     The portable access point  500  may additionally include a GPS (Global Positioning System) receiver  556  having an optional external antenna  558 . When the processor  502  detects an alarm condition, the processor  502  can obtain the current physical location of the portable access point  500  using the GPS receiver  556 . The alarm condition may be derived from abnormal readings from a physiological sensor  550 , or from manual input from the user, such as to the input device  518 . The processor  502  may periodically update its physical location information, so that if the GPS receiver cannot locate a signal (such as when inside), at least recent position information is available. 
     Upon detecting the alarm condition, the processor  502  generates an alarm message that contains the position information. The position information can help Emergency Medical Services to locate the patient. The alarm message may also include stored patient information, and historical and/or current physiological sensor  550  readings. The portable access point  500  then sends the alarm message wirelessly to a pre-programmed address. The alarm message is preferably encrypted, and may be sent in any suitable format (e.g., Short Message Service text message, email, eXtensible Markup Language message, etc.). The alarm message may also contain authentication information to prevent forged alarm messages. 
     Those skilled in the art can now appreciate from the foregoing description that the broad teachings of the present invention can be implemented in a variety of forms. Therefore, while this invention has been described in connection with particular examples thereof, the true scope of the invention should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, the specification and the following claims.