Abstract:
A method for establishing wireless communication comprising transmitting a request signal indicative of a request to establish communication with an external device external to a wireless communication device; determining at the wireless communication device based upon the request signal whether the external device communicates using a packet transmission protocol or a circuit switched transmission protocol; and if said external device communicates using a packet transmission protocol, transmitting subsequent communications from the wireless communication device directed to the external device using the packet transmission protocol.

Description:
BACKGROUND 
     1. Field of the Inventions 
     The field of the present inventions pertains to wireless communication systems, including among other things, a method and apparatus for wireless transmission of signals using both packet protocols and circuit switched protocols. 
     2. Description of the Related Art 
     Wireless communication systems are growing in size and number through out the world. A service that more and more wireless networks are providing is the transmission of data. Wireless networks also connect and interface with landline networks that do not use the same transmission protocols as the wireless networks. One group of popular protocols developed and used in landline networks for transmitting data are referred to as packet transmission protocols. These landline protocols are favored for transmitting data due to their robustness and flexibility. 
     Packet transmission protocols are especially common as Wide Area Network Protocols (WAN). Known packet protocols include X.25, TCP/IP and Frame Relay protocols. The TCP/IP protocol is used for transmission in Internet applications such as the World Wide Web (WWW), File Transfer Protocol (FTP) and Simple Mail Transfer Protocol (SMTP). 
     A wireless communication unit operating according to the CDPD (Cellular Digital Packet Data) protocol revision 1.1 established by the Wireless Data Forum, can transmit messages using a packet transmission protocol. Preferably, the wireless unit that is capable of transmitting data utilizing a CDPD protocol for data, should be able to switch between the packet data protocol and a circuit switched protocol depending on the service requested. However, in known wireless units switching between a packet protocol and a circuit switched protocol has required either manual user intervention or switching through the personal computer that the user is operating. Manual switching by the user either by physical switching or changing program settings is both time consuming and unreliable. Switching through the personal computer increases the processing overhead thereby decreasing the transmission rate. Further, switching by either the user or through the computer itself decreases the transmission rate since multiple interfaces may be required between the computer and the wireless transmission unit. An additional difficulty with having the switching capability reside in the computer or data device is that the computer operates using multiple clients, one for each protocol. The use of multiple clients increases the processing overhead and the complexity of the system. 
     SUMMARY OF THE INVENTIONS 
     The present invention comprises a wireless communication unit capable of communicating using both circuit switched transmission protocols and packet transmission protocols. The wireless communication unit is preferably able to switch between a circuit switched transmission protocol and a packet transmission protocol in a way which is transparent to the user, while at the same time minimizing the number of interfaces on the wireless communication unit and the number of clients that are required on a computer connected to the wireless communication unit. 
     In one embodiment a method for establishing wireless communication comprises transmitting a request signal to establish communication with an external device external to a wireless communication device; determining using the request signal the transmission protocol to be used for communication with the external device; if the external device communicates using a packet transmission protocol, transmitting from the wireless communication device to the external device using the transmission protocol of the external device. 
     In another embodiment a wireless communication device comprises a data terminal adapter that communicates with an external device using a particular protocol. A mobile subsystem communicates with the data terminal adapter. The mobile subsystem also communicates with the external device using a different transmission protocol. When the mobile subsystem receives a signal comprising a request to establish communication with the external device, it is determined which transmission protocol to use to communicate with the external device. 
     In yet another embodiment a wireless communication device comprises a multiple input and output switch. The switch couples the appropriate input to the appropriate output in response to a protocol signal. A packet server communicates with the switch and a data terminal adapter. A transceiver is coupled to the data terminal adapter and the packet server. A decoder is also coupled to the switch, wherein when the decoder receives a request signal for connection to a service capable of communicating using a particular protocol the decoder provides a protocol signal to the switch. 
     It is an object of an aspect of the present invention to create a wireless unit that can transmit signals both using a packet transmission protocol and a circuit switched transmission protocol, while maintaining an interface that is transparent to the user regardless of the transmission protocol used. 
     It is another object of an aspect of the present invention to create a wireless unit that can transmit signals both using a packet transmission protocol and a circuit switched transmission protocol, while minimizing the amount of configuration performed by the user. 
     It is yet another object of an aspect of the present invention to create a wireless unit that can transmit signals both using a packet transmission protocol and a circuit switched transmission protocol that has a uniform interface to the user regardless of the transmission protocol used. 
     This and other objects and aspects of the present invention are depicted and describe in the following drawings and detailed description thereof. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a diagram showing a wireless network capable of communicating using packets in conjunction with the present inventions. 
     FIG. 2 is a diagram of a packet enabled wireless communication unit according to a preferred embodiment of the present inventions. 
     FIG. 3 is a functional diagram showing the division of functions and the interfaces between the subsystems in a preferred embodiment of a wireless communication unit according to a preferred embodiment of the present inventions which is divided according to CDPD specifications. 
     FIG. 4 is a diagram showing the communication between the subsystems of a preferred wireless communication unit during a successful initialization of a packet data link between the wireless communications unit and an external data network according to a preferred embodiment of the present inventions. 
     FIG. 5 is a diagram showing the communication between the subsystems of a preferred wireless communication unit during a failed initialization of a packet data link between the wireless communication unit and an external data network according to a preferred embodiment of the present inventions. 
     FIG. 6 is a diagram showing the protocol layers used in a preferred embodiment of the present inventions which is compliant with the CDPD specifications. 
     FIG. 7 is a diagram showing the IP address allocation scheme according to the present invention. 
     FIG. 8 is a diagram showing the signaling paths and signal relay between the subsystems of a wireless communication system according to a preferred embodiment of the present inventions. 
     FIG. 9 is a first embodiment of a physical integration of the preferred components of a wireless communication system according to the present inventions. 
     FIG. 10 is a second embodiment of a physical integration of the preferred components of a wireless communication system according to the present inventions. 
     FIG. 11 is a third embodiment of a physical integration of the preferred components of a wireless communication system according to the present inventions. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1, mobile unit  5  communicates with a wireless base station  10 . Mobile unit  5  is able to connect to a network  15  through base station  10 . The network  15  can be a Public Service Telephone Network (PSTN), a data network or other communications network. Network  15  can for instance be a packet network that communicates using the Internet Protocol (IP). 
     A mobile unit  5 , is any sort of end-user product; from Laptop Computers to Vending Machines to a Package being tracked en route. The Mobile End System (MES) is the means by which the Network subscribers gain access to the available wireless communication services and is a functional description of the mobile unit and any attached data processing devices used in the wireless communication process. Mobile Unit  5  may be physically mobile or stationary, but is considered as always being potentially mobile. Furthermore, the physical location of mobile unit  5  may change with time, but continuous network access is maintained. Mobile unit  5  moves transparently from cell to cell or network to network in a fashion that is transparent to the end-user applications, for instance a web browser. 
     Referring to FIG. 2, a mobile unit  5  is the wireless device that is used for sending and receiving communications between the user and the network. In one embodiment the mobile unit is a customer premises radio unit (CPRU). The mobile unit  5  and user terminal  50  may be separate elements or an integrated device, various levels of integration between user terminal  50  and mobile unit  5  are discussed with respect to FIGS. 9-11 below. User terminal  50  runs the user applications such as e-mail clients, web browsers, word processors, etc. 
     User terminal  50 , which can also be referred to as the Data Terminal Equipment, can be a personal computer, a laptop computer, a Personal Digital Assistant (PDA), a Hand Held device or other device capable of processing data. User terminal  50  is connected to mobile unit  5  through a physical interface, which is preferably a serial port  55  although other interfaces such as parallel ports or busses can be used with the present inventions without departing from the scope of the present inventions. A factor in determining the interface type and method to be used is the level of integration between the user terminal  50  and the mobile unit  5 . 
     Communication Port  55 , which in personal computers is a serial port, is coupled to a switch  60  within mobile unit  5 . Switch  60  directs signals input into through port  55  to the Data Terminal Adapter (DTA)  65  or the Packet Data Server  70  depending on the communication protocol that the mobile unit  5  is utilizing. 
     Packet data server  70  frames outgoing packets and unframes incoming packets received by the mobile unit  5 . Packet data server  70  can be configured to support a number of packet transmission protocols including TCP/IP, X.25, Frame Relay or other packet transmission protocols. The packet data server  70  can be used to support one or more of the protocols in the same mobile unit, depending on the usage of the system. It is preferred in the case of a wireless modem that the system be able to support a number of different packet transmission protocols. 
     Number decoder  75  can be a database or other functionality that determines whether a specific telecommunications number associated with a request for connection to an external network is for a network that can communicate using a packet transmission protocol. In a preferred embodiment, the number decoder reads the telecommunications number input by the user unit  50  and then determines whether the telecommunications number corresponds to an stored list of numbers that support a packet transmission protocol that the packet data server  70  supports. The telecommunications number and connection type can be updated over the air by transmissions from the base station  10  and network  15 . It is further possible to store the network address of the network associated with the telecommunications number in the database. 
     In this way mobile unit  5  is capable of supporting transmission protocols for both circuit switched and packet based transmission. By using an intelligent switching system in the mobile unit  5 , the transmission mode used by the mobile unit  5  and network  15  is transparent to the user terminal  50 . Further, the preferred system allows for the use of a single client for communicating in both circuit switched and packet transmission protocols. The functionality of the preferred mobile unit  5  allows a user to simply transmit data to the mobile unit without having to determine whether the protocol is a packet transmission protocol or a circuit switched transmission protocol. The intelligent switching system of the present inventions saves the user time, computer processing overhead, increases reliability, and prevents errors and problems associated with manual user switching. 
     Data terminal adapter  65  and packet data server  70  are coupled to the communication circuitry  80  which is the circuitry that performs the over the air transmission, reception, modulation, and demodulation of signals and other functions required for the transmission of signals between the mobile unit  5  and the base station  10  (FIG.  1 ). 
     In the embodiment of FIG. 2 the mobile unit can be divided into the subscriber unit data terminal adapter (SU-DTA)  140  and a subscriber unit mobile station (SU-MS)  150  which would show the division of the physical system for the purposes of complying with revision 1.1 of the CDPD specification. 
     Referring to FIG. 3, Mobile Application Subsystem (MAS)  100  includes the Subscriber Applications  110  that function independently of the packet transmission protocol. The Subscriber Applications  110  include those functions that are required for general communication and data transmission, as well as the user applications and are independent of the network communication environment. Potential Subscriber Applications  110  include file transfer applications, electronic mail applications, remote terminal applications, remote monitoring applications, etc. The MAS  100  is a function or set of functions that preferably reside in the user terminal  50 . 
     MAS  100  communicates with SU-DTA  140  across a MAS-SU interface  130 . The SU-DTA  140  is the subsystem that supports both packet and circuit switched data protocols and related functions. The SU-MS  150  is the other communication circuitry  80  as seen in FIG.  2 . The SU-DTA  140  and the SU-MS  150  may be integrated to form a single subscriber unit (SU)  120 . Alternatively, the SU-DTA  140  and the SU-MS  150  may be separate physical entities. 
     The SU-DTA  140  supports the packet transmission protocols and functionality, and preferably supports a communication protocol that is compliant with the CDPD protocol. SU-DTA  140  and SU-MS  150  communicate across an MS-DTA interface  160 . Both the SU-DTA  140  and the SU-MS  150  both preferably reside within the mobile unit  5 . Subscriber Identity Module (SIM)  170  is the subsystem that defines the identity and access rights of the Mobile Unit  5  to the external network. Information contained in the SIM  170  includes the one more or unique Internet Protocol Address(es) assigned by the operator for use by mobile unit  5  and user device  50 . The SIM  170  also contains the telecommunications number database from which the number decoder  75  determines whether the desired communication service utilizes a packet transmission protocol for communication. The SIM further may contain the network address of each individual network  15  that corresponds to a specific telecommunications number. 
     SIM  170  communicates with the SU  120  across an SIM interface  180 . Alternatively, SIM  170  can be a subsystem of the SU  120  or the SU-MS  150 . Preferably, the SIM  170  communicate across the SIM interface  180  and does not communicate with the MAS  100  directly for security reasons. 
     The MAS-SU interface  130 , the MS-DTA interface  160  and the SIM interface  180  can be implemented as Application Program Interfaces (API&#39;s), hardware interfaces or a combination of the two, so long as communication between the subsystems is facilitated. The physical interface of the MAS-SU interface  130  can be a serial or bus connection, which creates a signal path between MAS  100  and SU-DTA  140 . The interface preferably is an AT interface that transfers signals in either a command or on-line data transmission mode. The entities of the MAS  100  and the SU-DTA  140  that communicate with each other are the communication drivers. The MAS  100  communications driver is preferably a standard communications driver that is shipped with the operating system of a PC or other similar device. The SU-DTA  140  communications driver is dependent on the type of SU  120  being used and preferably supports an AT interface. An interworking function which is one of the functions performed by the SU-DTA  140  communication driver, translates the AT commands to a command set which is used by the SU-DTA  140 . 
     Referring to FIG. 4, to initiate communication with an external network capable of packet based communication a reset signal  200  is sent from the MAS  100  to the SU-DTA  140 . SU-DTA  140  resets the mobile unit and then transmits a “resetok” signal  210  to the MAS  100 . The MAS  100  then sends the dial command with the telecommunications number  220 . Once the telecommunications number  220  is dialed and an initial connection is established, connect signal  230  is transmitted from the DTA  65  to the MAS  100 . Next the MAS  100  and SU-DTA  140  exchange a login sequence  240 . The login sequence  240  is dependent on the service type and software used by the mobile unit  5  and the service provider. 
     Once the login sequence  240  is completed the DTA  65  issues a connection request to the SU-MS  150  which begins a registration sequence with the data packet network. Once the SU-MS  150  establishes a link to the data packet network the SU-MS  150  transmits a signal indicating that a link with the data packet network has been established. Upon receiving to signal indicating that a link with the packet data network has been established, the SU-DTA  140  transmits a signal to the MAS  100  that the system can begin communication using a packet data format, i.e., using a SLIP or PPP network in the case of a wireless modem. 
     It should be noted that in the preferred embodiment of FIG. 4 the command mode used for communicating between the MAS  100  and the SU-DTA  140  is an AT command set which is compatible with most standard modems in use today. However, other command modes can be used for communication between the MAS  100  and the SU-DTA  140 , including proprietary manufacturer command modes. It is preferred for the purposes of being able to interchange mobile unit in many different systems that an industry standard command set, such as the preferred AT command set is used. 
     Referring to FIG. 5, the sequence for communication is the same as described with respect to FIG. 4 except that a registration failure command  300  is issued as opposed to a registration command  260 . The registration failure is transmitted from the mobile subsystem to the data terminal adapter at  310 . At  320 , a disconnect command is issued from the data terminal adapter to the user equipment. 
     Referring to FIG. 6, the protocol stack  350  describes the layers used for the purposes of transmitting information, i.e. packets. The physical layer  370  includes the components of the system in the packet data server  70 . MAC/RLC layer  380  provides for reliable low-level data transfer between the SU-MS  150  and the base station  10  and the means for establishing the link. MAC/RLC layer  380  is used for the transfer of user and control data. Logical link layer  390  provides end-to-end link control and establishment between SU-MS  150  and the base station  10 . Logical link layer  390  may also be used for the transfer of user and control data. The Sub Network Dependent Convergence Protocol (SNDCP) layer  400  translates the packets from an IP format to a format that can be transmitted over the logical link layer  390  for transmission within the base station  10 . Internet Protocol Layer  410  contains communications which are in the transparent packet format as well as the Internet Control Message Protocol which is used to inform the host system and routers of errors that occur in the network  15 . Internet Protocol Layer  410  may comprise sublayers for Point to Point (PPP) protocol and a Serial Link Internet Protocol (SLIP). Transfer Control Protocol Layer  420  is used to transfer and control the transmission of the packets between the mobile unit  5  and the network  15 . 
     SNDCP layer  400  is the highest layer in the protocol stack that preferably is able to communicate messages to the base station IO that are not routed on to the network  15 . The SNDCP layer  400  is also used to interface with MAS  100 . In this way information can be transferred from the SA  110  and can be translated into both IP packets and control signals immediately. Additionally, Internet Protocol header compression and encryption occurs in the SNDCP layer  400 . 
     Internet Protocol Layer  410  contains the functionality to allow the mobile unit  5  to be able to transfer packet data in the appropriate format with external networks. To be able to communicate with user terminal  50  through a serial port  55 , internet protocol layer will preferably operate using a Point to Point Protocol. The point to point protocol comprises three basic functions: (1) A method for encapsulating multi-protocol datagrams (packets); (2) Link Control Protocol for establishing, configuring and testing the data-link connection; and (3) Network Control Protocols for establishing different network-layer protocols. In a preferred embodiment of the present invention Internet Protocol Control Protocol as described in Internet Request For Comments No. 1332, “The PPP Internet Protocol Control Protocol (IPCP),” May 26, 1992. 
     In a preferred embodiment the SU  120  is the network host to the client MAS  100 . As can be seen in FIG. 7, the SU has an IP address that is assigned to it by the landline network  15 . The network  15  includes physical server with which the mobile unit  5  is communicating data using the packet protocol at issue, for instance IP. It can be seen that each MAS  100  is assigned a separate IP address, which is individual to each mobile unit  5  and can be stored in SIM  170 . The IP address assigned to each MAS  100  is invisible to the outside world, that is, the PPP connection established between MAS  100  and the SU  120  exists only between the two and all packets addressed to mobile unit  5  will be addressed to SU  120 . 
     Referring to FIG. 8, the SU-DTA  140  and the SU-MS  150  relay the packets between the network and the MAS  100 . The SU  120  also is capable of handling the standard IP header compression used. This compression/decompression occurs at the SNDCP layer  240  level (FIG.  6 ). Alternatively, the compressed headers may only be detected at the SNDCP layer  240  and the SU  120  can transmit the compressed header to the MAS  100  this would then perform the decompression. ICMP messages are transmitted between the SU  120  and the MAS  100 , and the SU  120  and the network  15 . The ICMP messages are the error messages that are supported by the IP. The SU  120  is preferably able to transmit the ICMP messages from the network to the MAS  100 . The following ICMP messages are preferably supported by the SU  120 : (1) The packet received from the MAS  100  is larger than the maximum transmission size of the mobile unit  5 ; (2) The network to which connection is attempted does not support the required packet transmission protocol; (3) That the header transmitted by the MAS has been determined by the network to be non-compliant with the appropriate transmission standard, it is also preferred that the exact header byte that contains the error is denoted by a pointer; (4) That the SU  120  buffer has reached overflow; and (5) That the received packets are overlarge and cannot be fragmented for transmission to the MAS  100 . The ICMP messages are addressed to the SU  120  by the network  15 . However, the SU  120  does not act on the message but simply routes them to the MAS  10  for action. 
     Referring to FIG. 9, DTA  65  translates the data from a wireless type to a serial type when the CPRU is operating using a circuit switched transmission mode. DTA  65  can connect to User Terminal  50  through a number of different methods in this embodiment amongst them being a PC card which resides in the PC, a cable connection to the PC&#39;s RS- 232  type serial port, or other any method which can be used to connect a PC to an external device. Mobile Station  600  transmits data and control information from the network  15  to the DTA  65 . In this embodiment, a separate circuit switched data path  610  and packet switched data path  620  exist between DTA  65  and MS  600 . Another data path  630  is used to communicate all information between the DTA  65  and the User Station  50 . 
     The MS  600  transmits signals to network  15  using forward communication channel  650  and receives signals from the network using reverse communication channel  640 . 
     Referring to FIG. 10, DTA  65  is an integrated portion of MS  600 , see FIG.  2 . In this arrangement signals are transmitted in the system similar to the transmissions described in FIG. 4, however the connection between DTA  65  and MS  600  is preferably a bus type connection. 
     Referring to FIG. 11, User Terminal  50 , DTA  65  and MS  600  are contained in an integrated unit. The arrangement in FIG. 11 is designed to perform data services, voice services and application services similar to a Personal Digital Assistant (PDA). 
     In the embodiments depicted in FIGS. 9,  10  and  11  it is preferred that SU-MS  150  subsystem resides in MS  600 , the SU-DTA  140  subsystem resides in DTA  65 , the application software of the MAS  100  subsystem resides in User Terminal  5 , and functions of SIM  170  subsystem reside in MS  600 . Other divisions of the functional components are possible, and the above divisions are not to be construed as limiting in any way. 
     While the embodiments, applications and advantages of the present invention have been depicted and described, there are many more embodiments, applications and advantages possible without deviating from the spirit of the inventive concepts described herein. The invention should therefore should only be restricted in accordance with the spirit of the claims appended hereto and is not restricted by the preferred embodiments, specification or drawings.