Abstract:
An apparatus for use in a wireless access terminal capable of accessing a 3G wireless network. The apparatus enables a host processing system to access the 3G wireless network using the wireless access terminal. The apparatus comprises: 1) a physical media dependent layer (PMDL) interface capable of transferring data between the wireless access terminal and the host processing system; and 2) an Ethernet emulation controller capable of communicating with the host processing system via the PMDL interface, wherein the Ethernet emulation controller emulates the operation of an Ethernet device adapter to thereby exchange data with the host processing system via an Ethernet protocol.

Description:
TECHNICAL FIELD OF THE INVENTION  
         [0001]    The present invention is directed generally to wireless communication systems and, more specifically, to an apparatus and method for emulating an Ethernet adapter in a 3G wireless mobile station.  
         BACKGROUND OF THE INVENTION  
         [0002]    In order to increase the wireless market to the greatest extent possible, wireless service providers and wireless equipment manufacturers constantly seek new ways to make wireless equipment and services as convenient, user-friendly, and affordable as possible. To that end, wireless service providers are upgrading the existing network infrastructure in order to deploy third generation (3G) wireless systems and services. The principle attractions of 3G systems are new non-voice services and higher data speeds. A number of standards have been proposed for 3G networks, including, for example, the Universal Mobile Telecommunication System (UMTS) standard. However, a key feature of all proposed 3G networks is a high-speed, always-on digital connection between the wireless network and each wireless access terminal.  
           [0003]    Consumers have been able to use cellular telephones (or similar wireless access terminals) to provide Internet connections to personal computers, especially lap top computers. This is typically accomplished by connecting the serial port of a host personal computer (PC) to the serial port of a cellular phone using a cable. The cellular phone acts as an analog modem for the host PC. The operator (or the host PC) uses the cell phone to dial the phone number of a dial-up connection to an Internet service provider. Once a connection was established, the host PC is able to browse the Internet as if the host PC was connected by an internal modem to a land line.  
           [0004]    3G cell phones and other 3G wireless access terminals will also be able to provide an Internet connection to a laptop computer or other host processing system. However, since a 3G-capable device is able to achieve a high data rate, using the 3G-capable device like an analog modem is an inefficient use of the resources of the wireless network. Among other things, operating a 3G phone like an analog modem entails unnecessary header and trailer encapsulation of IP frames. Also, the 3G phone establishes a conventional call connection to an Internet service provider (ISP). This is an always-on connection that ties up a radio channel for that cell phone, even if data is not being transferred to or from the host PC.  
           [0005]    Therefore, there is a need in the art for improved 3G wireless devices that may be connected to a host processing system in order to provide access to a data network. In particular, there is a need for 3G wireless access terminals that can provide a high-speed always-on digital data connection between a host PC and the Internet via a public wireless network.  
         SUMMARY OF THE INVENTION  
         [0006]    The present invention enables a 3G capable wireless access terminal (e.g., a UMTS cell phone) to appear like an Ethernet adapter to the operating system (e.g., Windows, Linux) of a host processing system (e.g., laptop PC). The present invention also enables the wireless access terminal to emulate the always-on nature of an Ethernet device.  
           [0007]    The present invention comprises a 3G wireless access terminal, such as a 3G cell phone, that has a Universal Serial Bus (USB) port (or similar data link) for host connectivity. A key feature of the present invention is making the cell phone (or other wireless access terminal) appear to be a USB-over-Ethernet device. According to an exemplary embodiment, the present invention comprises a USB device controller and other firmware on the cell phone and appropriate device drivers on the host PC (such as Windows, Linux). A USB cable provides connectivity between the host PC and the 3G cell phone.  
           [0008]    In alternate embodiments of the present invention, the USB connection between the host PC and the 3G wireless access terminal may be replaced with a similar suitable connection, such as a Firewire connection or a Bluetooth wireless connection. The precise physical connection used between the 3G wireless access terminal and the host PC is not critical. However, in all cases, the novelty is the ability to make a 3G wireless access terminal behave like an Ethernet device. Thus, the invention is a simple and effective way to use a 3G cell phone (or other wireless access terminal) with a host PC to get the high bandwidth advantages of a 3G connection.  
           [0009]    To address the above-discussed deficiencies of the prior art, it is a primary object of the present invention to provide, for use in a wireless access terminal capable of accessing a 3G wireless network, an apparatus for enabling a host processing system to access the 3G wireless network. According to an advantageous embodiment of the present invention, the apparatus comprises: 1) a physical media dependent layer (PMDL) interface capable of transferring data between the wireless access terminal and the host processing system; and 2) an Ethernet emulation controller capable of communicating with the host processing system via the PMDL interface, wherein the Ethernet emulation controller emulates the operation of an Ethernet device adapter to thereby exchange data with the host processing system via an Ethernet protocol.  
           [0010]    According to one embodiment of the present invention, the Ethernet emulation controller is capable of communicating with the wireless network via a wireless transceiver of the wireless access terminal.  
           [0011]    According to another embodiment of the present invention, the Ethernet emulation controller is further capable of emulating the operation of a Dynamic Host Configuration Protocol (DHCP) server to the host processing system.  
           [0012]    According to still another embodiment of the present invention, the PMDL interface comprises a wireline interface.  
           [0013]    According to yet another embodiment of the present invention, the PMDL interface comprises a wireless interface.  
           [0014]    The foregoing has outlined rather broadly the features and technical advantages of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features and advantages of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the art should appreciate that they may readily use the conception and the specific embodiment disclosed as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the invention in its broadest form.  
           [0015]    Before undertaking the DETAILED DESCRIPTION OF THE INVENTION below, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document: the terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation; the term “or,” is inclusive, meaning and/or; the phrases “associated with” and “associated therewith,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like; and the term “controller” means any device, system or part thereof that controls at least one operation, such a device may be implemented in hardware, firmware or software, or some combination of at least two of the same. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether locally or remotely. Definitions for certain words and phrases are provided throughout this patent document, those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, wherein like numbers designate like objects, and in which:  
         [0017]    [0017]FIG. 1 illustrates selected portions of a communication network in which a cellular phone emulates an Ethernet adapter according to the principles of the present invention;  
         [0018]    [0018]FIG. 2 illustrates an exemplary cellular phone in greater detail according to one embodiment of the present invention;  
         [0019]    [0019]FIG. 3 illustrates the interoperation of selected functional blocks in the cellular phone; and  
         [0020]    [0020]FIG. 4 illustrates the interoperation of selected network communication layers in the host personal computer and the exemplary cell phone according to the principles of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0021]    [0021]FIGS. 1 through 4, discussed below, and the various embodiments used to describe the principles of the present invention in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the invention. Those skilled in the art will understand that the principles of the present invention may be implemented in any suitably arranged wireless mobile station.  
         [0022]    [0022]FIG. 1 illustrates selected portions of communication network  100 , in which cell phone  130  emulates an Ethernet adapter according to the principles of the present invention. Communication network  100  comprises host processing system  110 , cell phone  130 , base station  140 , and packet data server node (PDSN)  150 . According to an exemplary embodiment of the present invention host processing system  110  is a personal computer (PC) comprising central processing unit (CPU)  112 , memory  114  (e.g., RAM), hard-disk drive (HDD)  116 , high speed digital interface (IF)  118 , and system bus  120 .  
         [0023]    Host processing system  110  can access base station  140  of a wireless network via cell phone  130 . High-speed digital interface  118  in host processing system  110  communicates with a similar high-speed digital interface  135  in cell phone  130  via data link  131 . Depending on the implementation, data link  131  may be a wireline link or a wireless link. According to the principles of the present invention, cell phone  130  emulates an Ethernet device adapter to host processing system  110 . Once an Ethernet connection is established between host processing system  110  and cell phone  130 , host processing system  110  may access the Internet via base station  140  and PDSN  150 .  
         [0024]    High-speed digital interfaces  118  and  135  may be any type of short-range wireline or wireless connections that can support an Ethernet link between host processing system  110  and cell phone  130 . For example, in a first embodiment of the present invention, high-speed digital interfaces  118  and  135  may comprise USB interfaces that communicate across a USB cable. In a second embodiment of the present invention, high-speed digital interfaces  118  and  135  may comprise Firewire interfaces that communicate across a Firewire cable. In a third embodiment of the present invention, high-speed digital interfaces  118  and  135  may comprise Bluetooth-capable wireless transceivers that communicate across a radio link.  
         [0025]    Those skilled in the art will understand that host processing system  110  and cell phone  130  are selected only for the purpose of illustrating the operation of the present invention. It will be appreciated by those skilled in the art that in other embodiments, host processing system  110  need not be a personal computer (PC) and cell phone  130  may be replaced by a number of different  3 G wireless access terminals. For example, in an alternate embodiment, host processing system  110  may be a router or switch that has a plurality of USB interfaces for interconnecting a number of network devices (e.g., a PC, a printer, a scanner, etc.) to cell phone  130 . Similarly, cell phone  130  may be replaced by a 3G-capable hand-held computer, such as a Palm or Handspring computer. Generally speaking, cell phone  130  represents any  3 G wireless access terminal and host processing system  110  represents any type of data device that can access a network via an Ethernet connection.  
         [0026]    [0026]FIG. 2 illustrates exemplary cell phone  130  in greater detail according to one embodiment of the present invention. Cell phone  130  comprises antenna  205 , radio frequency (RF) transceiver  210 , transmit (TX) processing circuitry  215 , microphone  220 , and receive (RX) processing circuitry  225 . Cell phone  130  also comprises speaker  230 , main processor  240 , high speed digital interface  135 , keypad  250 , display  255 , and memory  260 . Memory  260  stores basic operating system (OS) program  261 , Ethernet emulation control program  262 , Dynamic Host Configuration Protocol (DHCP) server program  263 , network configuration data field  264 , and Ethernet configuration data field  265 .  
         [0027]    Radio frequency (RF) transceiver  210  is a 3G wireless transceiver that receives from antenna  205  an incoming RF signal transmitted by a base station of wireless network  100 . Radio frequency (RF) transceiver  210  down-converts the incoming RF signal to produce an intermediate frequency (IF) or a baseband signal. The IF or baseband signal is sent to receiver (RX) processing circuitry  225  that produces a processed baseband signal by filtering, decoding, and/or digitizing the baseband or IF signal to produce a processed baseband signal. Receiver (RX) processing circuitry  225  transmits the processed baseband signal to speaker  230  (i.e., voice data) or to main processor  240  for further processing (e.g., web browsing).  
         [0028]    Transmitter (TX) processing circuitry  215  receives analog or digital voice data from microphone  220  or other outgoing baseband data (e.g., web data, e-mail, interactive video game data) from main processor  240 . Transmitter (TX) processing circuitry  215  encodes, multiplexes, and/or digitizes the outgoing baseband data to produce a processed baseband or IF signal. Radio frequency (RF) transceiver  210  receives the outgoing processed baseband or IF signal from transmitter (TX) processing circuitry  215 . Radio frequency (RF) transceiver  210  up-converts the baseband or IF signal to a radio frequency (RF) signal that is transmitted via antenna  205 .  
         [0029]    In an advantageous embodiment of the present invention, main processor  240  is a microprocessor or microcontroller. Memory  260  is coupled to main processor  240 . According to an advantageous embodiment of the present invention, part of memory  260  may comprise a random access memory (RAM) and another part of memory  260  may comprise a Flash memory, which acts as a read-only memory (ROM).  
         [0030]    Main processor  240  executes basic operating system (OS) program  261  stored in memory  260  in order to control the overall operation of cell phone  130 . In one such operation, main processor  240  controls the reception of forward channel signals and the transmission of reverse channel signals by radio frequency (RF) transceiver  210 , receiver (RX) processing circuitry  225 , and transmitter (TX) processing circuitry  215 , in accordance with well-known principles.  
         [0031]    Main processor  240  is capable of executing other processes and programs resident in memory  260 . Main processor  240  can move data into or out of memory  260 , as required by an executing process. Main processor  240  is also coupled to high-speed digital interface (IF)  135 . High-speed digital IF  135  provides cell phone  130  with the ability to connect to external devices, such as host processing system  110 .  
         [0032]    Main processor  240  is also coupled to keypad  250  and display unit  255 . The operator of cell phone  130  uses keypad  250  to enter data into cell phone  130 . Display  255  may be a liquid crystal display capable of rendering text and/or at least limited graphics from web sites. Alternate embodiments may use other types of displays.  
         [0033]    In accordance with the principles of the present invention, main processor  240  may execute Ethernet emulation control program  262  in order to emulate an Ethernet adapter over high-speed digital IF  135 . For the purposes of discussion, it will be assumed that basic operating system program  261  is Windows and that high-speed digital interfaces  118  and  135  are USB interface cards. However, this should not be construed so as to limit the generality of the present invention. Also, it is assumed that cell phone  130  is not initially connected to host processing system  110 .  
         [0034]    When cell phone  130  is hot-plugged into host processing system  110 , the USB drivers on host processing system  110  send configuration commands to the USB interface card in cell phone  130 . When cell phone  130  responds to the USB device driver in host processing system  110 , main processor  240 , under control of Ethernet emulation control program  262 , indicates that it is a Communications Device Class (CDC) device. At the same time, main processor  240  indicates the vendor ID and device ID to host processing system  110 . Host processing system  110  uses the vendor ID and the device ID to select the correct device driver for the CDC device associated with cell phone  130 .  
         [0035]    Next, main processor  240  indicates to host processing system  110  that the Ethernet link is DOWN. Subsequently, main processor  240  establishes a 3G data call over the air interface to base station  140  and PDSN  150 . As part of the 3G data call, main processor  240  receives an IP address, a netmask, Domain Name Server (DNS) information, and the like, from base station  140  of the wireless network. Main processor  240  stores this information in network configuration data field  264 . As soon as this information is available, main processor  240  indicates to host processing system  110  that the Ethernet link is UP.  
         [0036]    Since cell phone  130  appears to be an Ethernet device adapter to host processing system  110 , host processing system  110  issues DHCP commands to obtain the IP address and other information. Under the control of DHCP server program  263 , main processor  240  transmits the IP address, netmask, and DNS information obtained from the wireless network to host processing system  110 . Thus, host processing system  110  get its own IP address.  
         [0037]    If host processing system  110  is configured with a static IP address, then main processor  240  modifies the IP header as it traverses from the USB link (i.e., high-speed digital IF  135 ) to the air interface and vice-versa. The dynamic address given by the network is not given to host processing system  110 .  
         [0038]    Main processor  240  uses the Electronic Serial Number (ESN), or some other hardware key, of cell phone  130  along with its Public Land Mobile Network (PLMN) ID to generate two 48-bit Ethernet Medium Access Control (MAC) addresses, which are stored in Ethernet configuration data field  265 . Main processor  240  uses one of the MAC addresses as its own MAC address (i.e., as understood by host processing system  110 ). The other MAC address is used for responding to Address Resolution Protocol (ARP) requests from host processing system  110 . That is, when host processing system  110  issues ARP requests to resolve IP address to hardware address, main processor  240  responds with the second MAC address, thus indicating that the desired IP address can be reached via the USB link.  
         [0039]    [0039]FIG. 3 illustrates the interoperation of selected functional blocks in cell phone  130 . Ethernet emulation controller  320  represents main processor  240 , Ethernet emulation control program  262 , and DHCP server program  263 . On the air interface side, Ethernet emulation controller  320  controls RF transceiver  210  via 3G call stack  310 . 3G call stack  310  transfers outbound data packets from Ethernet emulation controller  320  to RF transceiver  210  and transfers inbound data packets from RF transceiver  210  to Ethernet emulation controller  320 .  
         [0040]    On the host processing system side, Ethernet emulation controller  320  emulates an Ethernet adapter in order to communicate with host processing system  110  via the physical media dependent layer (PMDL) of one or more high-speed digital interfaces  135 A,  135 B,  135 C and  135 D. In the illustrated embodiment, the physical media dependent layer (PMDL1) of high-speed digital interface  135 A is a Universal Serial Bus (USB) layer, the physical media dependent layer (PMDL2) of high-speed digital interface  135 B is a Firewire layer, the physical media dependent layer (PMDL3) of high-speed digital interface  135 C is a wireless Bluetooth layer, and the physical media dependent layer (PMDL4) of high-speed digital interface  135 D is some other conventional wireline or wireless layer. It is noted that high-speed digital interfaces  135 A,  135 B,  135 C and  135 D are shown for reference only. In most cases, due to the physical size limitations of cell phone  130 , only one of high-speed digital interfaces  135 A,  135 B,  135 C and  135 D is likely to be implemented in cell phone  130 .  
         [0041]    [0041]FIG. 4 illustrates the interoperation of selected network communication layers in the host personal computer and the exemplary cell phone according to the principles of the present invention. The illustrated network communication layers include personal computer (PC) network layers  410 , cell phone network layers  420 , and cell phone air interface (IF) layers  430 . PC network layers  410  are the conventional Windows, USB, Network Driver Interface Specification (NDIS), and Transmission Control Protocol/Internet Protocol (TCP/IP) layers found in host processing system  110 . PC network layers  410  comprise USB host controller layer  411 , USB Open Host Controller Interface/Universal Host Controller Interface (OHCI/UHCI) driver  412 , USB network driver  413 , and TCP/IP stack layer  415 .  
         [0042]    Each one of PC network layers  410  has a corresponding layer in cell phone network layers  420 , as indicated by the horizontal data flow arrows. Cell phone network layers  420  comprise USB device controller layer  421 , ARM USB driver  422 , USB network driver  423 , relay agent layer  424 , TCP/IP stack layer  425 , and DHCP server layer  426 . Relay agent layer  424  is required until an IP address is obtained from the wireless network. After that, the Ethernet packets are processed in a fast path directly from the USB driver to the air interface. USB device controller layer  421  and ARM USB driver  422  are conventional cell phone layers for controlling a USB interface. The present invention resides in the upper layers, namely USB network driver  423 , relay agent layer  424 , TCP/IP stack layer  425 , and DHCP server layer  426 . Cell phone air interface layers  430  are conventional air interface software layers in cell phone  130 . Cell phone air interface layers  430  comprise UMTS L2 and below layers  431  and Radio Access Bearer Management (RABM) layer  432 .  
         [0043]    Although the present invention has been described in detail, those skilled in the art should understand that they can make various changes, substitutions and alterations herein without departing from the spirit and scope of the invention in its broadest form.