WO2001011903A1 - Ultra-thin client wireless terminal - Google Patents

Ultra-thin client wireless terminal Download PDF

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Publication number
WO2001011903A1
WO2001011903A1 PCT/US2000/021295 US0021295W WO0111903A1 WO 2001011903 A1 WO2001011903 A1 WO 2001011903A1 US 0021295 W US0021295 W US 0021295W WO 0111903 A1 WO0111903 A1 WO 0111903A1
Authority
WO
WIPO (PCT)
Prior art keywords
wireless
data
packet
terminal
wireless terminal
Prior art date
Application number
PCT/US2000/021295
Other languages
French (fr)
Inventor
Adisak Mekkittikul
Original Assignee
Berkeley Concept Research Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US09/513,367 external-priority patent/US6690657B1/en
Application filed by Berkeley Concept Research Corporation filed Critical Berkeley Concept Research Corporation
Publication of WO2001011903A1 publication Critical patent/WO2001011903A1/en

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Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04WWIRELESS COMMUNICATION NETWORKS
    • H04W4/00Services specially adapted for wireless communication networks; Facilities therefor
    • H04W4/18Information format or content conversion, e.g. adaptation by the network of the transmitted or received information for the purpose of wireless delivery to users or terminals
    • GPHYSICS
    • G06COMPUTING; CALCULATING OR COUNTING
    • G06FELECTRIC DIGITAL DATA PROCESSING
    • G06F1/00Details not covered by groups G06F3/00 - G06F13/00 and G06F21/00
    • G06F1/16Constructional details or arrangements
    • G06F1/1613Constructional details or arrangements for portable computers
    • G06F1/1626Constructional details or arrangements for portable computers with a single-body enclosure integrating a flat display, e.g. Personal Digital Assistants [PDAs]
    • GPHYSICS
    • G06COMPUTING; CALCULATING OR COUNTING
    • G06FELECTRIC DIGITAL DATA PROCESSING
    • G06F1/00Details not covered by groups G06F3/00 - G06F13/00 and G06F21/00
    • G06F1/16Constructional details or arrangements
    • G06F1/1613Constructional details or arrangements for portable computers
    • G06F1/1633Constructional details or arrangements of portable computers not specific to the type of enclosures covered by groups G06F1/1615 - G06F1/1626
    • G06F1/1684Constructional details or arrangements related to integrated I/O peripherals not covered by groups G06F1/1635 - G06F1/1675
    • G06F1/1698Constructional details or arrangements related to integrated I/O peripherals not covered by groups G06F1/1635 - G06F1/1675 the I/O peripheral being a sending/receiving arrangement to establish a cordless communication link, e.g. radio or infrared link, integrated cellular phone
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04WWIRELESS COMMUNICATION NETWORKS
    • H04W28/00Network traffic management; Network resource management
    • H04W28/02Traffic management, e.g. flow control or congestion control
    • H04W28/06Optimizing the usage of the radio link, e.g. header compression, information sizing, discarding information
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04WWIRELESS COMMUNICATION NETWORKS
    • H04W4/00Services specially adapted for wireless communication networks; Facilities therefor
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04WWIRELESS COMMUNICATION NETWORKS
    • H04W88/00Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
    • H04W88/02Terminal devices
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04WWIRELESS COMMUNICATION NETWORKS
    • H04W88/00Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
    • H04W88/14Backbone network devices
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02DCLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00Reducing energy consumption in communication networks
    • Y02D30/70Reducing energy consumption in communication networks in wireless communication networks

Definitions

  • This invention pertains generally to personal computing devices, and more particularly to components of a personal computing device having separate CPU (central processing unit) and graphical user interface devices connected by a wireless link
  • the "desktop" computer offers the most computing functionality, e g , the latest, fastest (and most power-hungry) processors— even multiple processors — large banks of memory, multiple magnetic and optical storage media, extra bus slots for expandability, large, high-resolution displays, and the ability to connect to a large number of peripherals
  • the tradeoff for all this power and flexibility is that the desktop computer is generally large and heavy, requires an AC power supply, and, practically, must remain tethered in a generally fixed location by a my ⁇ ad of wired connections
  • a user mav alternately select a "portable”, “laptop”, or “notebook” computer instead of a desktop computer when portability is a high priority
  • Laptop computers generally have a footprint roughly the size of a sheet of notebook paper, are one to two inches thick, and have a display screen that flips up to reveal a full-size keyboard
  • some laptops offer fast processors, large memory banks, and multiple storage media, this generally involves a tradeoff between functionality and weight and/or battery life
  • Those laptops with greater functionality may weight six to eight pounds, while those with lesser functionality may weigh as few as three to five pounds
  • Most laptops can function on battery power for only a few hours without recharging
  • laptops can run the same software as desktop computers, although some applications may run noticeably faster on a desktop.
  • Handheld computers use much slower processors and have no disk drive, relying instead on flash memory cartridges for non-volatile data and program storage. These devices generally weigh less than two pounds, with the smallest devices fitting in a shirt pocket and weighing less than half a pound. Battery life is generally on the order of eight hours, although some small devices can function much longer on one charge.
  • the present disclosure presents a new type of personal computing and entertainment device for use in a wireless local network.
  • this device combines the strengths of desktop, laptop, and handheld computers while minimizing their weaknesses — and adding additional functionality.
  • the disclosed embodiments accomplish this by offloading tasks that are typically performed by a central processing unit (CPU), random access memory (RAM), and/or peripheral storage devices to a server computer. With these tasks offloaded, the remaining device needs no complex operating system, CPU, program storage, or data storage.
  • the simplified device communicates with the server wirelessly, and can thus be described as a "wireless terminal".
  • the wireless terminal is reduced, essentially, to graphics processing and display, user input sensing, and wireless communication with a server.
  • the wireless terminal When connected to the server over the wireless network, the wireless terminal functions as a "virtual" personal computer.
  • the server has the computing power and data handling capability necessary to perform demanding computing tasks such as Internet browsing, e-mail management, word processing, spreadsheets, and multimedia applications;
  • the terminal provides user input capability and display capability in a preferably lightweight, low-power, and inexpensive device.
  • all of the functionality of a powerful desktop can appear to be available, e.g., in the form factor of an untethered handheld device.
  • a wireless terminal comprises a display device, a graphics processor, a wireless transceiver, and an input bridge (e.g., a peripheral controller).
  • the input bridge accepts user input and supplies that input to the wireless transceiver as packet- formatted user input data.
  • the wireless transceiver transmits packet-formatted user input data to a remote computing system over a first wireless data channel.
  • the wireless transceiver also receives packet-formatted graphics data generated by the remote computing system in response to the input data, over a second wireless channel.
  • a graphics processor converts the graphics data into a format compatible with the display device.
  • a wireless graphical user interface for a computing system comprises a wireless transceiver to communicate over a wireless channel with a wireless terminal.
  • the interface further comprises a video adapter to convert display data to packet-formatted graphics data, and to submit the packet- formatted graphics data to the wireless transceiver for transmission to the wireless terminal.
  • the wireless interface also comprises an input driver to accept packet-formatted user input data received by the wireless transceiver from the wireless terminal, and to convert those packets to user inputs for the computer.
  • the input driver converts the packet-formatted user input data into user input compatible with a computing system coupled to the interface.
  • a method of interfacing a computer with a user via a wireless terminal is also disclosed.
  • an input device coupled to a wireless terminal accepts user input.
  • the user input is converted to packet format and transmitted over a wireless channel to a remote computing system.
  • the wireless terminal receives digitally-compressed graphical data packets back from the remote computing system over the same, or a different, wireless channel.
  • the wireless terminal converts the graphical data packets to a display format for display on a display device coupled to the wireless terminal.
  • Figure 1 shows an exemplary deployment of wireless network components in a wireless local area network capable of supporting operation of an embodiment of the invention
  • Figure 2 shows selected components from Figure 1 in one operational configuration including a personal computer
  • Figure 3 shows network stack components for a computing device configured to serve a wireless terminal
  • Figure 4 shows selected components from Figure 1 in a second operational configuration including a wireless entertainment gateway
  • Figure 5 shows a high-level block diagram for a wireless terminal according to an embodiment of the invention
  • Figure 6 shows a top view of the physical appearance of a wireless terminal according to an embodiment of the invention
  • Figure 7 shows a high-level block diagram for the wireless terminal shown in Figure 6; and Figure 8 shows network stack components for a wireless terminal according to an embodiment of the invention
  • a wireless channel is a communication channel or subchannel that uses RF transmission methods to convey digital information
  • a channel is not limited to any particular modulation scheme
  • Packet-formatted data is data that is partitioned into finite- length blocks of digital symbols for individual block transmission from a data source to a data sink
  • a graphics processor manipulates graphical digital information, e g , from a compressed digital format to a bitmapped format or vice versa
  • a video adapter generally includes a graphics processor, and produces an output in a format compatible with a display device
  • a wireless device can appear (to the video adapter) to be the display device — thus the compatible format can be a format compatible with wireless transmission
  • a computing device or system accepts digital input and executes stored program instructions in response to that input to produce a digital output
  • Figure 1 shows one possible operational environment useful with the present invention As this is a preferred environment, a short explanation of the operation of the underlying wireless networking infrastructure is appropriate as an introduction to the detailed embodiments
  • the networking infrastructure depicted in Figure 1 uses multiple types of wireless channels to provide desired network functionality
  • This channel is used to provide control communications between the va ⁇ ous devices served by the network and base station 24
  • This channel also provides a highly-reliable, low bit-rate data path for networked devices
  • At least one high bit-rate channel (an N3 link) can also exist within the network
  • the high bit-rate channel can provide the data transfer capability needed for video, graphics, and high-speed data communications.
  • the high bit- rate channel As compared to the low bit-rate channel, the high bit- rate channel generally achieves high data transfer rates at the expense of range, security, interference immunity, and/or overall reliability.
  • a wireless RF channel operating in a GHz band In order to serve high bit-rate devices, a wireless RF channel operating in a GHz band
  • At least three related exemplary approaches are available for providing both high data-rate and high-reliability, long-range wireless communication.
  • a primary, relatively low bit-rate NO channel is implemented using a spread spectrum RF channel, e.g., in the 900 MHz ISM band, while secondary, relatively high bit-rate N3 channels are implemented using one of the GHz bands.
  • a primary NO channel and a secondary N3 channel are both implemented using one of the GHz bands, with at least the primary channel using spread spectrum modulation.
  • NO and N3 channel transmission can overlap in time, as long as the NO and N3 signals themselves are substantially non-overlapping.
  • the two channels can use different DSSS (Direct Sequence Spread Spectrum) spreading codes with a common RF carrier, with the NO channel having a substantially higher chip rate than the N3 channel due to the NO channel's lower bit rate.
  • the third approach is similar to the second, except that the two channels are also time- division multiplexed onto the same physical carrier and are logically separated by the receiver.
  • the operational concepts described below can be deployed in a network using any of these three approaches.
  • the NO channel capabilities are imbedded in all network devices. Using the NO channel, the base station 24 admits authorized devices into network 20. The base station uses the NO channel to control and configure the wireless operation of each other network device, including establishing N3 links between network peers.
  • the N3 channel is optimized for streaming information at relatively high data rates from one high data-rate (HD) device to another HD device.
  • an N3 channel will generally use a high RF carrier frequency to allow high data rate transmission.
  • High bit-rate modulation i.e., high bps/Hz
  • An N3 link can be a one-way, peer-to-peer connection between two HD devices.
  • a two-way channel can be created by placing both an N3 transmitter and an N3 receiver at each HD device and configuring a two-way channel between them.
  • Each HD device also incorporates an NO link, with N3 links being under the control of the NO link.
  • wireless terminal 22 can communicate over an NO link with base station 24 when given permission by base station 24.
  • Wireless terminal 22 can use the NO link to request that an N3 channel be set up from PC 26 to terminal 22.
  • the base station uses its NO links to pass configuration requests to PC 26, wireless terminal 22, and any other devices (e.g., wireless repeater 30) that may be needed to create an end-to-end N3 channel from 26 to 22. If these requests are acknowledged, an N3 channel is created by base station 24 to serve the desired connection.
  • Wireless terminal 22 can display graphical output produced by desktop PC 26. Alternately, wireless terminal 22 can display video from wireless entertainment gateway 28.
  • NO control channel terminal 22 can readily switch between PC 26 and gateway 28 as a graphical input supplier.
  • NO channel as a data channel, terminal 22 can pass user input to PC 26 or to gateway 28 via base station 24. The selected computing system can then respond to the user input as if it were generated by an input device physically attached to that computing system.
  • Figure 2 shows a portion of wireless network 20 — the portion needed to utilize wireless terminal 22 with PC 26.
  • wireless terminal 22 and PC 26 each communicate with base station 24 over their respective NO links.
  • terminal 22 wishes to send user input data to PC 26, it transmits the data in a packet to base station 24 over NO; base station 24 forwards the packet over NO to PC 26.
  • PC 26 transmits high-rate packet-formatted graphics over an N3 link to wireless repeater 30, which repeats the data from the N3 link to wireless terminal 22 over a second N3 link.
  • no repeater is necessary.
  • PC 26 is shown as a high-level block diagram.
  • Host CPU 32 and RAM 34 communicate across a frontside bus 38.
  • a bridge 36 allows host CPU 32 to communicate with various peripherals across a PCI local bus 40, and also allows the peripherals to initiate direct memory access (DMA) operations to RAM 34.
  • One of these peripherals is a network interface card (NIC) that connects PC 26 to a wired network, such as a 10/100 or Gigabit Ethernet local area network, a cable data services network, or the PSTN (e.g., through an ISDN, DSL, or analog modem).
  • Video adapter 44 converts bit-mapped graphics, e.g., stored in VRAM (video RAM), to a video format compatible with a local display device.
  • PC 26 contains several other components not typical of a prior art PC.
  • a wireless controller 46 connects to PCI local bus 40.
  • Wireless controller 46 controls wireless transceiver 48, which is capable of NO and N3 operation as described above.
  • video adapter 44 supplies packet-formatted graphics data to wireless controller 46 (although shown as a separate connection for clarity, the connection can be implemented across PCI local bus 40 if sufficient bandwidth is available).
  • these components form a "wireless" graphical user interface to the computer, where user input and output take place across a wireless link.
  • the interaction between video adapter 44, wireless controller 46, wireless transceiver 48, and host CPU 32 will now be further explained with reference to Figure 3.
  • Wireless transceiver 48 receives wireless packets over NO that have the MAC address assigned to 802.11 MAC 54. Each received packet passes through logical link controller (LLC) 56, which may be implemented in either wireless controller 46 or transceiver 48.
  • LLC logical link controller
  • Channel control packets from the base station are passed up to NO channel control manager 58, and to N3 channel access control manager 62 if the packets relate to an N3 channel.
  • Data packet received over the NO channel are passed up to the appropriate network layer handler, e.g., IP layer 70 of Figure 3.
  • graphics data packets slated for transmission over the N3 channel pass in the reverse direction.
  • NO channel control manager 58 and N3 channel access control manager 62 peer with the base station to effectuate control of the wireless links.
  • Channel management controls 60 ensure that operation of the wireless LLC, MAC, and PHY conform to the access granted by the base station, e.g., time slots, frequency, modulation, spreading codes, power, etc., as assigned for each channel.
  • Wireless controller 46 preferably implements managers 58 and 62 and channel management controls 60, although it is possible to implement at least some of this functionality in software running on host CPU 32.
  • wireless controller 46 transfers the data packet to RAM 34 using a DMA operation.
  • Wireless controller 46 can then interrupt host CPU 32 to notify it that a packet has arrived.
  • the host CPU processes the packet using wireless controller driver software, network driver interface software, and TCP/IP software (when the packet is a TCP/IP packet).
  • the data packet is passed from TCP 64 up to the application assigned to the TCP port.
  • a wireless terminal When a wireless terminal is linked to PC 26, user inputs sensed at the wireless terminal are transmitted to PC 26 in NO data packets. These data packets are passed up stack 50, as described above, to input driver 66 (an application running on host CPU 32). Input driver 66 interprets each user input data packet to produce an appropriate input, e.g., to higher-level applications. For instance, when the user moves a pointing device attached to the wireless terminal, the terminal generates a wireless NO packet describing the movement. Input driver 66 interprets this packet and reports the movement to a higher-level application as if the pointing device were physically connected to PC 26. The higher-level application can respond to the movement as if it were performed on a local pointing device.
  • Video adapter 44 normally reads data from the VRAM in a raster order at a designated refresh rate (e.g., 72 Hz) to produce a video signal for an attached local display.
  • a refresh rate e.g. 72 Hz
  • the video adapter must take a different approach (even at eight-bit resolution, wireless transmission of VRAM digital data at this resolution and refresh rate would require roughly a 500 million bps data rate).
  • video adapter 44 takes advantage of spatial and temporal redundancy in the VRAM contents, thereby compressing the VRAM data to a more manageable data transfer rate.
  • video adapter 44 can apply a well-known compression algorithm such as MPEG-2 or JPEG2000 to the VRAM data.
  • video adapter 44 could potentially use host CPU 32 to effect compression, it is preferable that the computational burden of compression be absorbed by video adapter hardware.
  • the video adapter may have particular insight into how the VRAM image is being manipulated. This insight can allow image coding to avoid exhaustive image block matching that must occur when the coder has no prior knowledge of how the image is changing from frame to frame.
  • Video adapter 44 blocks the compressed display data into graphics data packets.
  • the packets are supplied to, e.g., a UDP transport layer 68 for transmission over the N3 channel to the linked wireless terminal.
  • Figure 4 shows a different subset of wireless network 20 than Figure 2 shows.
  • This subset allows a user to utilize wireless terminal 22 with entertainment gateway 28.
  • the communication between terminal 22 and gateway 28 generally follows what has been described in relation to Figures 2 and 3. But the function of entertainment gateway 28 differs from that of PC 26.
  • Entertainment gateway 28 allows any one of several video sources to be viewed on wireless terminal 22. These sources can include digitally-compressed video sources, such as data streams read from a Digital Video Disk (DVD) or digital video tape, received with a Digital Satellite System (DSS) receiver or High-Definition TV (HDTV) receiver, stored on a computer-readable disk, or received over a packet data or digital cable network. Such sources have generally already been compressed to a bandwidth suitable for the N3 link.
  • entertainment gateway can also accept analog video sources, such as standard broadcast NTSC or PAL signals, cable television signals, video cassette player output, etc. These sources require digitization and compression before they can be placed on the N3 link.
  • a wireless terminal when linked to entertainment gateway 28, can control the function of gateway 28 via a wireless terminal input device. For instance, a user depressing an appropriate button on the wireless terminal can generate an input data packet containing a request for a menu. Gateway 28 interprets the request and sends a graphical menu to wireless terminal 22 for display. The user can then select from the menu a desired source.
  • Input driver 88 functions much like input driver 66 ( Figure 3) of PC 26, interpreting user input data packets and sending user commands to source selector 84.
  • source selector 84 can switch the source data stream directly to wireless controller 82.
  • the source may already be arranged in suitable packets; if not, either the source selector can block the data stream into packets, or supply the data stream to wireless controller 82 for packetization.
  • the source signal is switched to video compressor 86, which uses real time video coding to compress the source video into graphics data.
  • the graphics data may leave video compressor 86 as a series of packets, or as a data stream that will be packetized further downstream.
  • FIG. 5 shows a high-level block diagram for a simple wireless terminal embodiment 22.
  • a wireless transceiver 100 receives packet- formatted graphics data from a remote computing system such as PC 26 of Figure 2.
  • the transceiver also transmits packet- formatted user input data to the remote computing system, preferably over a separate channel than that used for the graphics data.
  • Wireless transceiver 100 supplies received graphics data to graphics processor 102.
  • This processor has the capability to run a companion decoder to the remote computing system's video encoder.
  • Graphics processor 102 uses the decoder to convert the packet- formatted graphics data into a format compatible with the display device.
  • Memory 104 can buffer previously-received display frames and packets that are awaiting the decode process. Memory 104 may also have a current frame buffer that graphics processor 102 (or display device 106) reads to create a displayable image format.
  • Input/output bridge 108 interfaces wireless transceiver 100 with user input devices coupled to terminal 22.
  • Bridge 108 accepts user input from the input devices and supplies that input to wireless transceiver 100 as packet-formatted user input data.
  • Bridge 108 preferably can also bridge output to output devices, such as an audio amplifier and speaker pair.
  • the potentially CPU-less wireless terminal can potentially place the full power and user output capability of the remote computing system "at" the wireless terminal. Because the terminal requires only the basic hardware needed for user input, display output, and wireless communication, it becomes a much smaller challenge to reduce the size, weight, and power consumption of the device to levels far below those required for a full-function laptop computer.
  • Figure 6 shows, in top view, one potential physical configuration for a wireless terminal 200 according to the invention.
  • the surface of the device is dominated by active matrix display 210, e.g. a commercially-available 15.1 -inch diagonal, 1024x768 pixel color thin-film-transistor (TFT) liquid crystal display.
  • active matrix display 210 e.g. a commercially-available 15.1 -inch diagonal, 1024x768 pixel color thin-film-transistor (TFT) liquid crystal display.
  • TFT thin-film-transistor
  • buttons 214, 216, 218 allow a user a familiar point-and-chck interface Touchscreen capability, along with stylus 208, allow a user to directly access displayed "buttons” and other graphical controls, input handw ⁇ ting as strokes, etc And a set of programmable buttons 220 arranged below display 210 can be used to access common functions
  • a USB port allows a conventional mouse, keyboard, etc to be attached to terminal 200 as well
  • An auxiliary serial port offers similar functionality
  • a number of output ports are preferably integrated into device 200
  • audio and video output ports allow the terminal's output to be directed to other devices, such as recording devices
  • An IEEE 1394 port allows terminal 200 to accept — or output — high- rate digital data
  • all input and output ports are optional, as well as their locations on terminal 200
  • Figure 7 shows a high-level block diagram for the internal electronics of terminal 200
  • the electronic components are generally arranged as several subsystems wireless communication, output, input, power, and device control Each subsystem connects to a system bus 244
  • the wireless communication subsystem comprises wireless transceiver 240 and wireless controller 242 Generally, transceiver 240 and controller 242 function in the same manner as their counterparts in PC 26 ( Figure 2) Wireless transceiver 240 generally needs to transmit and receive on NO, but only needs to receive on N3 Depending on the wireless channel scheme employed, this may or may not lead to a wireless subsystem design that differs slightly from that used in PC 26
  • the output subsystem comprises graphics/audio processor 250, audio interface 252, video interface 254, video memory 256, and display controller 258
  • Graphics/audio processor 250 decodes graphics and audio packets received from a remote computing system, updating video memory 256 with a bitmapped version of the most current display output and supplying decoded audio to audio interface 252
  • Display controller 258 reads video memory 256 and produces appropriate signals to display 210 to display the image contained in video memory 256
  • Terminal 200 can also be configured such that video is output to video interface 254 as well
  • the input subsystem comprises peripheral controllers 260 A controller handles each type of user input, producing input data that can be supplied to wireless controller 242 and/oi another subsystem of terminal 200
  • Power management 270 couples to system bus 244 and power subsystem 272 Power management 270 can notify other components to enter "low-power” or “sleep” modes when they are unneeded and the system is running on battery, as well as monitoring the condition of power subsystem 272 and alerting the user when power is low
  • the device control subsystem comprises CPU 280, b ⁇ dge/memory controller 282, main memory 284, and nonvolatile (e g , flash) memory 286
  • a CPU is not strictly necessary for the device to interface with a remote computing system
  • the CPU/memory system can provide several advantages First, it provides for the ability to run lightweight applications, such as control of a wireless home security system, remote control of audio/video equipment, or configuration of the terminal itself, in a standalone mode with no wireless server computer attached Second, it provides a straightforward way to change or upgrade the functionality of other system components, e g , by storing firmware for those components in nonvolatile memory 286
  • Another advantage is the ability to run some software in support of the other system components, such as TCP/IP, etc
  • the availability of a CPU and memory although not st ⁇ ctly necessary, adds flexibility to the device operation
  • CPU 280 and memory 284 are fairly minimal devices, e.g., with insufficient capacity to run high-end PC operating systems and related applications
  • the wireless terminal's principal operational feature as it relates to the invention regardless, remains as the ability to serve as a remote wireless graphical user interface for a computing device.
  • Figure 8 shows a partial stack 300 for wireless terminal 200.
  • the function of stack 300 is generally analogous to that already described for stack 50 ( Figure 3) of PC 26.
  • User inputs entered on a USB input device pass to peripheral controller 260, and are packaged in TCP/IP packets for transmission as NO data packets to, e.g., PC 26.
  • Resulting graphics data packets are received on the N3 channel, and pass upwards to graphics processor 250 for decoding and display.
  • Channel control from the wireless base station is handled in a similar manner to that administered in PC 26.
  • the remote computer can prioritize wireless transmission of screen changes due to user control manipulation to partially alleviate this problem.
  • the wireless terminal can be left in charge of tracking and visually indicating cursor positioning using a bitmap overlay function of the graphics processor. Current absolute cursor position is supplied to the remote computer. When the remote computer changes the cursor appearance, the remote computer can simply supply a new cursor bitmap to the wireless terminal.

Abstract

A wireless terminal (22), companion circuitry for a remote computer (26), and a method for their operation is disclosed. The architecture of the terminal is designed to leverage a high data rate wireless network to remove the necessity for a general-purpose CPU and associated storage devices in the terminal. The terminal (22) wirelessly linked to a centralized server (24) having the CPU and storage capacity to run desired applications. User inputs at the terminal are wirelessly transmitted to the server, which runs the applications and produces a corresponding graphical display output. The display output is digitally compressed and wirelessly transmitted to the terminal. A graphics processor at the terminal decompresses the display output for display at the terminal. When operating in this mode, the wireless terminal can become a lightweight, low power 'virtual PC' or entertainment display device.

Description

ULTRA-THIN CLIENT WIRELESS TERMINAL
FIELD OF THE INVENTION
This invention pertains generally to personal computing devices, and more particularly to components of a personal computing device having separate CPU (central processing unit) and graphical user interface devices connected by a wireless link
BACKGROUND OF THE INVENTION
Personal computing devices are available in a variety of different form factors, each generally optimized for a given set of user needs The "desktop" computer offers the most computing functionality, e g , the latest, fastest (and most power-hungry) processors— even multiple processors — large banks of memory, multiple magnetic and optical storage media, extra bus slots for expandability, large, high-resolution displays, and the ability to connect to a large number of peripherals The tradeoff for all this power and flexibility is that the desktop computer is generally large and heavy, requires an AC power supply, and, practically, must remain tethered in a generally fixed location by a myπad of wired connections
A user mav alternately select a "portable", "laptop", or "notebook" computer instead of a desktop computer when portability is a high priority Laptop computers generally have a footprint roughly the size of a sheet of notebook paper, are one to two inches thick, and have a display screen that flips up to reveal a full-size keyboard Although some laptops offer fast processors, large memory banks, and multiple storage media, this generally involves a tradeoff between functionality and weight and/or battery life Those laptops with greater functionality may weight six to eight pounds, while those with lesser functionality may weigh as few as three to five pounds Most laptops can function on battery power for only a few hours without recharging In general, laptops can run the same software as desktop computers, although some applications may run noticeably faster on a desktop. A user can choose to trade away some of this capability for even smaller size by selecting a "handheld" computer. Handheld computers use much slower processors and have no disk drive, relying instead on flash memory cartridges for non-volatile data and program storage. These devices generally weigh less than two pounds, with the smallest devices fitting in a shirt pocket and weighing less than half a pound. Battery life is generally on the order of eight hours, although some small devices can function much longer on one charge.
Larger handheld computers can run trimmed-down versions of desktop computer operating system and application software on a smaller display screen with a smaller keyboard. Smaller handheld computers have even smaller displays, use a stylus and handwriting recognition software for text input, and run small, special-purpose software programs to perform a limited subset of computing tasks.
SUMMARY OF THE INVENTION
The present disclosure presents a new type of personal computing and entertainment device for use in a wireless local network. Preferably, this device combines the strengths of desktop, laptop, and handheld computers while minimizing their weaknesses — and adding additional functionality. In general, the disclosed embodiments accomplish this by offloading tasks that are typically performed by a central processing unit (CPU), random access memory (RAM), and/or peripheral storage devices to a server computer. With these tasks offloaded, the remaining device needs no complex operating system, CPU, program storage, or data storage. The simplified device communicates with the server wirelessly, and can thus be described as a "wireless terminal". The wireless terminal is reduced, essentially, to graphics processing and display, user input sensing, and wireless communication with a server. When connected to the server over the wireless network, the wireless terminal functions as a "virtual" personal computer. The server has the computing power and data handling capability necessary to perform demanding computing tasks such as Internet browsing, e-mail management, word processing, spreadsheets, and multimedia applications; the terminal provides user input capability and display capability in a preferably lightweight, low-power, and inexpensive device. To the user, all of the functionality of a powerful desktop can appear to be available, e.g., in the form factor of an untethered handheld device.
In one aspect of the invention, a wireless terminal is disclosed. The terminal comprises a display device, a graphics processor, a wireless transceiver, and an input bridge (e.g., a peripheral controller). The input bridge accepts user input and supplies that input to the wireless transceiver as packet- formatted user input data. The wireless transceiver transmits packet-formatted user input data to a remote computing system over a first wireless data channel. The wireless transceiver also receives packet-formatted graphics data generated by the remote computing system in response to the input data, over a second wireless channel. A graphics processor converts the graphics data into a format compatible with the display device.
In another aspect of the invention, a wireless graphical user interface for a computing system is disclosed. The wireless interface comprises a wireless transceiver to communicate over a wireless channel with a wireless terminal. The interface further comprises a video adapter to convert display data to packet-formatted graphics data, and to submit the packet- formatted graphics data to the wireless transceiver for transmission to the wireless terminal. The wireless interface also comprises an input driver to accept packet-formatted user input data received by the wireless transceiver from the wireless terminal, and to convert those packets to user inputs for the computer. The input driver converts the packet-formatted user input data into user input compatible with a computing system coupled to the interface. A method of interfacing a computer with a user via a wireless terminal is also disclosed. In this method, an input device coupled to a wireless terminal accepts user input. The user input is converted to packet format and transmitted over a wireless channel to a remote computing system. The wireless terminal receives digitally-compressed graphical data packets back from the remote computing system over the same, or a different, wireless channel. The wireless terminal converts the graphical data packets to a display format for display on a display device coupled to the wireless terminal.
BRIEF DESCRIPTION OF THE DRAWINGS
The embodiments described below can be best understood with reference to the drawing, wherein:
Figure 1 shows an exemplary deployment of wireless network components in a wireless local area network capable of supporting operation of an embodiment of the invention;
Figure 2 shows selected components from Figure 1 in one operational configuration including a personal computer;
Figure 3 shows network stack components for a computing device configured to serve a wireless terminal;
Figure 4 shows selected components from Figure 1 in a second operational configuration including a wireless entertainment gateway; Figure 5 shows a high-level block diagram for a wireless terminal according to an embodiment of the invention;
Figure 6 shows a top view of the physical appearance of a wireless terminal according to an embodiment of the invention;
Figure 7 shows a high-level block diagram for the wireless terminal shown in Figure 6; and Figure 8 shows network stack components for a wireless terminal according to an embodiment of the invention
DETAILED DESCRIPTION OF THE EMBODIMENTS
Throughout the following description, several terms have defined meanings As used herein a wireless channel is a communication channel or subchannel that uses RF transmission methods to convey digital information A channel is not limited to any particular modulation scheme Packet-formatted data is data that is partitioned into finite- length blocks of digital symbols for individual block transmission from a data source to a data sink A graphics processor manipulates graphical digital information, e g , from a compressed digital format to a bitmapped format or vice versa A video adapter generally includes a graphics processor, and produces an output in a format compatible with a display device In the present invention, a wireless device can appear (to the video adapter) to be the display device — thus the compatible format can be a format compatible with wireless transmission A computing device or system accepts digital input and executes stored program instructions in response to that input to produce a digital output
Figure 1 shows one possible operational environment useful with the present invention As this is a preferred environment, a short explanation of the operation of the underlying wireless networking infrastructure is appropriate as an introduction to the detailed embodiments The networking infrastructure depicted in Figure 1 uses multiple types of wireless channels to provide desired network functionality This includes at least one low bit-rate channel (an NO link) that is designed for high reliability This channel is used to provide control communications between the vaπous devices served by the network and base station 24 This channel also provides a highly-reliable, low bit-rate data path for networked devices At least one high bit-rate channel (an N3 link) can also exist within the network The high bit-rate channel can provide the data transfer capability needed for video, graphics, and high-speed data communications. As compared to the low bit-rate channel, the high bit- rate channel generally achieves high data transfer rates at the expense of range, security, interference immunity, and/or overall reliability. In order to serve high bit-rate devices, a wireless RF channel operating in a GHz band
(such as one of the Industrial, Scientific, and Medical (ISM) bands or a low-power Unlicensed National Information Infrastructure (U-NII) band) is generally required. But signals in these bands fade extremely rapidly due to absorption. Thus it can be difficult to implement a high data rate, highly reliable channel over any appreciable distance in one of the GHz bands. Thus in the examples below, the channel characteristics used for control communications and user input, which have relatively low data rate requirements (albeit at a high reliability), differ from the characteristics of the channel used for high bit-rate data transfer. Also, repeaters (shown) and/or wireless switches (not shown) can be used to extend the coverage of a high data-rate (N3) channel. At least three related exemplary approaches are available for providing both high data-rate and high-reliability, long-range wireless communication. In the first approach, a primary, relatively low bit-rate NO channel is implemented using a spread spectrum RF channel, e.g., in the 900 MHz ISM band, while secondary, relatively high bit-rate N3 channels are implemented using one of the GHz bands. In the second approach, a primary NO channel and a secondary N3 channel are both implemented using one of the GHz bands, with at least the primary channel using spread spectrum modulation. NO and N3 channel transmission can overlap in time, as long as the NO and N3 signals themselves are substantially non-overlapping. For instance, the two channels can use different DSSS (Direct Sequence Spread Spectrum) spreading codes with a common RF carrier, with the NO channel having a substantially higher chip rate than the N3 channel due to the NO channel's lower bit rate. The third approach is similar to the second, except that the two channels are also time- division multiplexed onto the same physical carrier and are logically separated by the receiver. The operational concepts described below can be deployed in a network using any of these three approaches. The NO channel capabilities are imbedded in all network devices. Using the NO channel, the base station 24 admits authorized devices into network 20. The base station uses the NO channel to control and configure the wireless operation of each other network device, including establishing N3 links between network peers.
The N3 channel is optimized for streaming information at relatively high data rates from one high data-rate (HD) device to another HD device. For instance, an N3 channel will generally use a high RF carrier frequency to allow high data rate transmission. High bit-rate modulation (i.e., high bps/Hz) is also generally preferred, even if this lowers the channel's reliability somewhat. An N3 link can be a one-way, peer-to-peer connection between two HD devices. A two-way channel can be created by placing both an N3 transmitter and an N3 receiver at each HD device and configuring a two-way channel between them. Each HD device also incorporates an NO link, with N3 links being under the control of the NO link.
For instance, in Figure 1, wireless terminal 22 can communicate over an NO link with base station 24 when given permission by base station 24. Wireless terminal 22 can use the NO link to request that an N3 channel be set up from PC 26 to terminal 22. The base station uses its NO links to pass configuration requests to PC 26, wireless terminal 22, and any other devices (e.g., wireless repeater 30) that may be needed to create an end-to-end N3 channel from 26 to 22. If these requests are acknowledged, an N3 channel is created by base station 24 to serve the desired connection.
In Figure 1, two possible remote computing systems for wireless terminal 22 are shown. Wireless terminal 22 can display graphical output produced by desktop PC 26. Alternately, wireless terminal 22 can display video from wireless entertainment gateway 28. Using the NO control channel, terminal 22 can readily switch between PC 26 and gateway 28 as a graphical input supplier. Using the NO channel as a data channel, terminal 22 can pass user input to PC 26 or to gateway 28 via base station 24. The selected computing system can then respond to the user input as if it were generated by an input device physically attached to that computing system.
Figure 2 shows a portion of wireless network 20 — the portion needed to utilize wireless terminal 22 with PC 26. Again, wireless terminal 22 and PC 26 each communicate with base station 24 over their respective NO links. When terminal 22 wishes to send user input data to PC 26, it transmits the data in a packet to base station 24 over NO; base station 24 forwards the packet over NO to PC 26. PC 26 transmits high-rate packet-formatted graphics over an N3 link to wireless repeater 30, which repeats the data from the N3 link to wireless terminal 22 over a second N3 link. Of course, if the terminal 22 and PC 26 are in close enough proximity that a direct N3 link can be established, no repeater is necessary. In Figure 2, PC 26 is shown as a high-level block diagram. Many of the hardware components of PC 26 (and their configuration) are well-known in the art. Host CPU 32 and RAM 34 communicate across a frontside bus 38. A bridge 36 allows host CPU 32 to communicate with various peripherals across a PCI local bus 40, and also allows the peripherals to initiate direct memory access (DMA) operations to RAM 34. One of these peripherals is a network interface card (NIC) that connects PC 26 to a wired network, such as a 10/100 or Gigabit Ethernet local area network, a cable data services network, or the PSTN (e.g., through an ISDN, DSL, or analog modem). Video adapter 44 converts bit-mapped graphics, e.g., stored in VRAM (video RAM), to a video format compatible with a local display device. Many other peripherals, such as magnetic or optical mass storage media, are typically also accessible through PCI local bus 40, but have not been shown in Figure 2. In the embodiment of Figure 2, PC 26 contains several other components not typical of a prior art PC. First, a wireless controller 46 connects to PCI local bus 40. Wireless controller 46 controls wireless transceiver 48, which is capable of NO and N3 operation as described above. And video adapter 44 supplies packet-formatted graphics data to wireless controller 46 (although shown as a separate connection for clarity, the connection can be implemented across PCI local bus 40 if sufficient bandwidth is available). Together, these components form a "wireless" graphical user interface to the computer, where user input and output take place across a wireless link. The interaction between video adapter 44, wireless controller 46, wireless transceiver 48, and host CPU 32 will now be further explained with reference to Figure 3.
Wireless transceiver 48 receives wireless packets over NO that have the MAC address assigned to 802.11 MAC 54. Each received packet passes through logical link controller (LLC) 56, which may be implemented in either wireless controller 46 or transceiver 48. Channel control packets from the base station are passed up to NO channel control manager 58, and to N3 channel access control manager 62 if the packets relate to an N3 channel. Data packet received over the NO channel are passed up to the appropriate network layer handler, e.g., IP layer 70 of Figure 3. Likewise, graphics data packets slated for transmission over the N3 channel pass in the reverse direction.
NO channel control manager 58 and N3 channel access control manager 62 peer with the base station to effectuate control of the wireless links. Channel management controls 60 ensure that operation of the wireless LLC, MAC, and PHY conform to the access granted by the base station, e.g., time slots, frequency, modulation, spreading codes, power, etc., as assigned for each channel. Wireless controller 46 preferably implements managers 58 and 62 and channel management controls 60, although it is possible to implement at least some of this functionality in software running on host CPU 32. When a data packet arrives over the wireless link, wireless controller 46 transfers the data packet to RAM 34 using a DMA operation. Wireless controller 46 can then interrupt host CPU 32 to notify it that a packet has arrived. The host CPU processes the packet using wireless controller driver software, network driver interface software, and TCP/IP software (when the packet is a TCP/IP packet). The data packet is passed from TCP 64 up to the application assigned to the TCP port.
When a wireless terminal is linked to PC 26, user inputs sensed at the wireless terminal are transmitted to PC 26 in NO data packets. These data packets are passed up stack 50, as described above, to input driver 66 (an application running on host CPU 32). Input driver 66 interprets each user input data packet to produce an appropriate input, e.g., to higher-level applications. For instance, when the user moves a pointing device attached to the wireless terminal, the terminal generates a wireless NO packet describing the movement. Input driver 66 interprets this packet and reports the movement to a higher-level application as if the pointing device were physically connected to PC 26. The higher-level application can respond to the movement as if it were performed on a local pointing device.
One common response to user input is an update to bitmapped display data, e.g., a 1024-pixel-wide by 768-pixel-high, eight-, sixteen-, or thirty-two-bit-deep array stored in VRAM. Video adapter 44 normally reads data from the VRAM in a raster order at a designated refresh rate (e.g., 72 Hz) to produce a video signal for an attached local display. When the display is directed to a wireless terminal, the video adapter must take a different approach (even at eight-bit resolution, wireless transmission of VRAM digital data at this resolution and refresh rate would require roughly a 500 million bps data rate).
Preferably, video adapter 44 takes advantage of spatial and temporal redundancy in the VRAM contents, thereby compressing the VRAM data to a more manageable data transfer rate. For instance, video adapter 44 can apply a well-known compression algorithm such as MPEG-2 or JPEG2000 to the VRAM data. Although video adapter 44 could potentially use host CPU 32 to effect compression, it is preferable that the computational burden of compression be absorbed by video adapter hardware. Note that, particularly where the video adapter incorporates a graphics accelerator, the video adapter may have particular insight into how the VRAM image is being manipulated. This insight can allow image coding to avoid exhaustive image block matching that must occur when the coder has no prior knowledge of how the image is changing from frame to frame.
Video adapter 44 blocks the compressed display data into graphics data packets. The packets are supplied to, e.g., a UDP transport layer 68 for transmission over the N3 channel to the linked wireless terminal.
Turning now to a second operational configuration, Figure 4 shows a different subset of wireless network 20 than Figure 2 shows. This subset allows a user to utilize wireless terminal 22 with entertainment gateway 28. The communication between terminal 22 and gateway 28 generally follows what has been described in relation to Figures 2 and 3. But the function of entertainment gateway 28 differs from that of PC 26.
Entertainment gateway 28 allows any one of several video sources to be viewed on wireless terminal 22. These sources can include digitally-compressed video sources, such as data streams read from a Digital Video Disk (DVD) or digital video tape, received with a Digital Satellite System (DSS) receiver or High-Definition TV (HDTV) receiver, stored on a computer-readable disk, or received over a packet data or digital cable network. Such sources have generally already been compressed to a bandwidth suitable for the N3 link. Preferably, entertainment gateway can also accept analog video sources, such as standard broadcast NTSC or PAL signals, cable television signals, video cassette player output, etc. These sources require digitization and compression before they can be placed on the N3 link. A wireless terminal, when linked to entertainment gateway 28, can control the function of gateway 28 via a wireless terminal input device. For instance, a user depressing an appropriate button on the wireless terminal can generate an input data packet containing a request for a menu. Gateway 28 interprets the request and sends a graphical menu to wireless terminal 22 for display. The user can then select from the menu a desired source. Input driver 88 functions much like input driver 66 (Figure 3) of PC 26, interpreting user input data packets and sending user commands to source selector 84.
When the user selects a compressed video source, source selector 84 can switch the source data stream directly to wireless controller 82. The source may already be arranged in suitable packets; if not, either the source selector can block the data stream into packets, or supply the data stream to wireless controller 82 for packetization.
When the user selects an analog or uncompressed digital video source, the source signal is switched to video compressor 86, which uses real time video coding to compress the source video into graphics data. The graphics data may leave video compressor 86 as a series of packets, or as a data stream that will be packetized further downstream.
The remaining description focuses on embodiments of a wireless terminal. Figure 5 shows a high-level block diagram for a simple wireless terminal embodiment 22. A wireless transceiver 100 receives packet- formatted graphics data from a remote computing system such as PC 26 of Figure 2. The transceiver also transmits packet- formatted user input data to the remote computing system, preferably over a separate channel than that used for the graphics data.
Wireless transceiver 100 supplies received graphics data to graphics processor 102. This processor has the capability to run a companion decoder to the remote computing system's video encoder. Graphics processor 102 uses the decoder to convert the packet- formatted graphics data into a format compatible with the display device. Memory 104 can buffer previously-received display frames and packets that are awaiting the decode process. Memory 104 may also have a current frame buffer that graphics processor 102 (or display device 106) reads to create a displayable image format.
Input/output bridge 108 interfaces wireless transceiver 100 with user input devices coupled to terminal 22. Bridge 108 accepts user input from the input devices and supplies that input to wireless transceiver 100 as packet-formatted user input data. The following are some examples of the types of input devices that can be used with terminal 22: a mouse, a trackball, a joystick, a j-stick (i.e., a cursor stick), a touchpad, a touchscreen, a stylus, a keyboard, a scroll wheel, function buttons, and a microphone. Bridge 108 preferably can also bridge output to output devices, such as an audio amplifier and speaker pair.
With these basic components and the companion components that have been described for a remote computing system, the potentially CPU-less wireless terminal can potentially place the full power and user output capability of the remote computing system "at" the wireless terminal. Because the terminal requires only the basic hardware needed for user input, display output, and wireless communication, it becomes a much smaller challenge to reduce the size, weight, and power consumption of the device to levels far below those required for a full-function laptop computer.
Figure 6 shows, in top view, one potential physical configuration for a wireless terminal 200 according to the invention. The surface of the device is dominated by active matrix display 210, e.g. a commercially-available 15.1 -inch diagonal, 1024x768 pixel color thin-film-transistor (TFT) liquid crystal display. Near the upper corners of display 210, left and right speakers 202, 204 provide audio output. Audio input is provided by microphone 206 near the bottom of display 210. Terminal 200 offers several built-in input devices besides microphone 206. A control stick 212 and "mouse" buttons 214, 216, 218 allow a user a familiar point-and-chck interface Touchscreen capability, along with stylus 208, allow a user to directly access displayed "buttons" and other graphical controls, input handwπting as strokes, etc And a set of programmable buttons 220 arranged below display 210 can be used to access common functions A USB port allows a conventional mouse, keyboard, etc to be attached to terminal 200 as well An auxiliary serial port offers similar functionality
A number of output ports are preferably integrated into device 200 For instance, audio and video output ports allow the terminal's output to be directed to other devices, such as recording devices An IEEE 1394 port allows terminal 200 to accept — or output — high- rate digital data Of course, all input and output ports are optional, as well as their locations on terminal 200
Figure 7 shows a high-level block diagram for the internal electronics of terminal 200 The electronic components are generally arranged as several subsystems wireless communication, output, input, power, and device control Each subsystem connects to a system bus 244
The wireless communication subsystem comprises wireless transceiver 240 and wireless controller 242 Generally, transceiver 240 and controller 242 function in the same manner as their counterparts in PC 26 (Figure 2) Wireless transceiver 240 generally needs to transmit and receive on NO, but only needs to receive on N3 Depending on the wireless channel scheme employed, this may or may not lead to a wireless subsystem design that differs slightly from that used in PC 26
The output subsystem comprises graphics/audio processor 250, audio interface 252, video interface 254, video memory 256, and display controller 258 Graphics/audio processor 250 decodes graphics and audio packets received from a remote computing system, updating video memory 256 with a bitmapped version of the most current display output and supplying decoded audio to audio interface 252 Display controller 258 reads video memory 256 and produces appropriate signals to display 210 to display the image contained in video memory 256 Terminal 200 can also be configured such that video is output to video interface 254 as well
The input subsystem comprises peripheral controllers 260 A controller handles each type of user input, producing input data that can be supplied to wireless controller 242 and/oi another subsystem of terminal 200
Power management 270 couples to system bus 244 and power subsystem 272 Power management 270 can notify other components to enter "low-power" or "sleep" modes when they are unneeded and the system is running on battery, as well as monitoring the condition of power subsystem 272 and alerting the user when power is low
The device control subsystem comprises CPU 280, bπdge/memory controller 282, main memory 284, and nonvolatile (e g , flash) memory 286 Although a CPU is not strictly necessary for the device to interface with a remote computing system, the CPU/memory system can provide several advantages First, it provides for the ability to run lightweight applications, such as control of a wireless home security system, remote control of audio/video equipment, or configuration of the terminal itself, in a standalone mode with no wireless server computer attached Second, it provides a straightforward way to change or upgrade the functionality of other system components, e g , by storing firmware for those components in nonvolatile memory 286 Another advantage is the ability to run some software in support of the other system components, such as TCP/IP, etc In short, the availability of a CPU and memory, although not stπctly necessary, adds flexibility to the device operation Preferably, CPU 280 and memory 284 are fairly minimal devices, e.g., with insufficient capacity to run high-end PC operating systems and related applications. It should be noted that this is a design issue, however, and that an embodiment with a high-level standalone capability is also possible. The wireless terminal's principal operational feature as it relates to the invention, regardless, remains as the ability to serve as a remote wireless graphical user interface for a computing device.
Figure 8 shows a partial stack 300 for wireless terminal 200. The function of stack 300 is generally analogous to that already described for stack 50 (Figure 3) of PC 26. User inputs entered on a USB input device pass to peripheral controller 260, and are packaged in TCP/IP packets for transmission as NO data packets to, e.g., PC 26. Resulting graphics data packets are received on the N3 channel, and pass upwards to graphics processor 250 for decoding and display. Channel control from the wireless base station is handled in a similar manner to that administered in PC 26.
It is noted that with user inputs handled remotely, the possibility exists for occasional disconcerting delays between when a user attempts to manipulate, e.g., a cursor, and when the cursor actually moves on the display. The remote computer can prioritize wireless transmission of screen changes due to user control manipulation to partially alleviate this problem. Alternately, the wireless terminal can be left in charge of tracking and visually indicating cursor positioning using a bitmap overlay function of the graphics processor. Current absolute cursor position is supplied to the remote computer. When the remote computer changes the cursor appearance, the remote computer can simply supply a new cursor bitmap to the wireless terminal.
Those of ordinary skill will understand that various aspects of the embodiments described above can be combined or altered to create additional embodiments. Partitioning of the described functions between different hardware components, as well as between hardware, firmware, and software, is largely a design consideration. The display screen size, display technology, and resolution are also design considerations, although preferably a color display with sufficient resolution to represent common PC application displays is provided. It is further noted that the remote computer that is behind the wireless terminal need not have a wireless connection itself — for instance, a wired Ethernet connection can be used to tie a server or other remote computer to a separate device that actually provides a wireless link to the wireless terminal. One PC can potentially serve multiple wireless terminals concurrently, each wireless terminal running a separate instance of the PC's serving capability. Such alternate implementations are intended to fall within the scope of the invention as claimed below.
The preceding embodiments are exemplary. Specific standards and protocols illustrate a few possible configurations; the invention is applicable to configurations using alternate, additional, and/or new standards and protocols. Although the specification may refer to "an", "one", "another", or "some" embodiment(s) in several locations, this does not necessarily mean that each such reference is to the same embodiment(s), or that the feature only applies to a single embodiment.

Claims

WHAT IS CLAIMED IS:
1. A wireless terminal comprising: a wireless transceiver to transmit packet-formatted user input data to a remote computing system over a first wireless data channel and to receive packet- formatted graphics data, generated by the remote computing system in response to the packet- formatted user input data, over a second wireless data channel; a display device; a graphics processor to convert the packet- formatted graphics data into a format compatible with the display device; and an input bridge to accept user input and supply that input to the wireless transceiver as packet-formatted user input data.
2. The wireless terminal of claim 1, wherein the wireless transceiver comprises a wireless controller to operate the transceiver according to an access profile granted by a remote base station.
3. The wireless terminal of claim 1, wherein the wireless transceiver has the capability to receive packet- formatted audio data from the remote computing system, the terminal further comprising an audio processor to convert the packet-formatted audio data into a format compatible with an audio output device.
4. The wireless terminal of claim 1, further comprising an input device to generate the user input, the input device coupled to the input bridge.
. The wireless terminal of claim 4, wherein the input device comprises at least one of the devices selected from the list consisting of a mouse, a trackball, a joystick, a j-stick, a touchpad, a touchscreen, a stylus, a keyboard, a scroll wheel, function buttons, and a microphone.
6. The wireless terminal of claim 1, wherein the wireless transceiver has the capability to receive packet terminal configuration data from the remote computing system, the terminal configuring itself according to the terminal configuration data.
7. The wireless terminal of claim 1 , further comprising a central processing unit and associated read/write memory to control configuration of the terminal.
8. The wireless terminal of claim 1, further comprising a video memory coupled to the graphics processor, the video memory storing the graphics data as a bitmapped image.
9. The wireless terminal of claim 8, further comprising a display controller to read the bitmapped image from the video memory.
10. The wireless terminal of claim 1, wherein the packet-formatted graphics data arrive at the wireless terminal in a digitally-compressed video format, the" graphics processor comprising a digital video decoder capable of decompressing the graphics data.
11. A wireless terminal comprising: means for wirelessly transmitting digital data packets to a remote computing system over a first channel and receiving digital data packets from the remote computing system over a second channel; a display device; means for converting digital compressed video data packets received from the remote computing system over the second channel into a video format compatible with the display device; and means for encapsulating user inputs into digital data packets and placing those packets on the first channel.
12. A wireless graphical user interface for a computing system, the interface comprising: a wireless transceiver capable of communication over a wireless channel with a wireless terminal; a video adapter to convert display data to packet-formatted graphics data, and to submit the packet-formatted graphics data to the wireless transceiver for transmission to the wireless terminal; and an input driver to accept packet- formatted user input data received by the wireless transceiver from the wireless terminal, and to convert the packet-formatted user input data into user input compatible with a computing system coupled to the interface.
13. The interface of claim 12, wherein the video adapter comprises a video compressor to compress the display data.
14. The interface of claim 12, further comprising a source selector to select, in response to the user input, one of a plurality of sources of display data for conversion to packet-formatted graphics data.
5. The interface of claim 12, wherein the wireless transceiver comprises a wireless controller to operate the transceiver according to an access profile granted by a remote base station.
16. A method of interfacing a computer with a user via a wireless terminal comprising: accepting user input generated by an input device coupled to the wireless terminal; converting the user input to packet format; transmitting the packet-foπnatted user input over a first wireless channel to a remote computing system; receiving packet-formatted digital compressed video data back from the remote computing system over a second wireless channel; converting the packet-formatted graphical data to a display format compatible with a display device coupled to the wireless terminal; and displaying the display-formatted graphical data on the display device.
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