CA2153148A1 - Method and apparatus of providing time sensitive message over a variable delay channel - Google Patents
Method and apparatus of providing time sensitive message over a variable delay channelInfo
- Publication number
- CA2153148A1 CA2153148A1 CA002153148A CA2153148A CA2153148A1 CA 2153148 A1 CA2153148 A1 CA 2153148A1 CA 002153148 A CA002153148 A CA 002153148A CA 2153148 A CA2153148 A CA 2153148A CA 2153148 A1 CA2153148 A1 CA 2153148A1
- Authority
- CA
- Canada
- Prior art keywords
- digital data
- message
- terminal equipment
- stream
- receiving
- Prior art date
- Legal status (The legal status 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 status listed.)
- Abandoned
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W28/00—Network traffic management; Network resource management
- H04W28/02—Traffic management, e.g. flow control or congestion control
- H04W28/06—Optimizing the usage of the radio link, e.g. header compression, information sizing, discarding information
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/12—Arrangements for detecting or preventing errors in the information received by using return channel
- H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
- H04L1/18—Automatic repetition systems, e.g. Van Duuren systems
- H04L1/1809—Selective-repeat protocols
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M11/00—Telephonic communication systems specially adapted for combination with other electrical systems
- H04M11/06—Simultaneous speech and data transmission, e.g. telegraphic transmission over the same conductors
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
- H04N1/00095—Systems or arrangements for the transmission of the picture signal
- H04N1/00103—Systems or arrangements for the transmission of the picture signal specially adapted for radio transmission, e.g. via satellites
- H04N1/00106—Systems or arrangements for the transmission of the picture signal specially adapted for radio transmission, e.g. via satellites using land mobile radio networks, e.g. mobile telephone
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W76/00—Connection management
- H04W76/10—Connection setup
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W92/00—Interfaces specially adapted for wireless communication networks
- H04W92/16—Interfaces between hierarchically similar devices
- H04W92/18—Interfaces between hierarchically similar devices between terminal devices
Abstract
An apparatus and method of providing communications between standard unmodified terminal equipment over a telephone link that includes a digital wireless link. The digital wireless link introduces substantial time variable delay. In order to pass time sensitive messages over the link, time sensitive messages are recognized and translated into time insensitive messages for transmission over the wireless link. The time insensitive messages indicate the information contained in the time sensitive messages and in the timing of the time sensitive messages. At the receiving end, the time insensitive messages are recognized and the time sensitive messages reconstructed with the appropriate timing.
Description
~ W095/14356 21S 3~48 PCT/US94/130S'1 METHOD AND APPARATUS OF PROVIDING TIME SENSI'rIVE
MESSAGE OVER A VARL~ E DELAY CHANNEL
BACKGROUND OF THE INVENTION
I. Field of the Invention The present invention relates to communication. More particularly, the present invention relates to a novel and improved method and 10 apparatus for providing communication over a digital link.
II. Description of the Related Art A variety of apparatus exists today that use standard telephone 15 networks to convey data from one terminal to another. One of th~ most coIrunon terminals that uses a standard te~ephone network to convey data is the facsimile (FAX) machine. Like other terminal equipment that use standard telephone networks, a FAX machine uses a modem to translate digital information to audible analog tones for transmission over the 20 telephone networlc. At the receiving PAX machine, a modem is used to convert the tones Dack into an estimate of the original digital information sent by the transmitting FAX machin~.
With the deployment of cellular and personal communications wireless systems, the end ~ser may wish to connect his terminal equipment 25 to a mobile communications device instead of directly to a land telephone network. However, if the user attempts to send the audible tones produced by a modem over a standard analog FM cellular channel, it is doubtful that he will be successful. In general, the FM cellular channel introduces a substantial amount of noise into the link compared to the standard land 30 telephone network. The additional noise translates into errors in the estimation of the digital information wn~n the signal is converted at the receiving end. The errors on the link can be overcome by constraining communications to very low transmission rates.
If the end user attempts to send the audible tones produced by a 35 modem over a standard digital wireless channel, it is also doubtful that he will be successful. Digital wireless communication equipment typically uses vocoders to convert incoming voice signals into digital bits for transmission over the channel. Vocoders are tailored to sample and compress human voice. Because modem tones differ significantly from human voice, the 40 vocoder can cause noticeable degradation to the modem tones. Also, 2 1 ~ 3 ~ 4 8 PCT/US94113091 maximizing the capacity of the system in terms of the number of simultaneous users that can be handled is extremely important in a system using a wireless link. Digitizing modem tones with a vocoder and sending them over the digital wireless link is an ineffic ellt use of the radio channel..7 A more efficient, flexible, and reliable transmission means is to provide a mechanism to transmit the digital data over the digital wireless link directly. This configuration presents some unique opportunities to take advantage of the digital link to provide high quality service.
A typical digital wireless link is not an error free channel. To provide 1~ error free communication, the wireless link protocol may provide re-transmission of lost or corrupted data. The re-transmissions introduce arbitrary and significant delays in the data. When the time sensitive messages are transmitted over the wireless link, the timing of the signals may be lost thus prohibiting proper communications.
It is therefore the object of the present invention to provide an efficient method and apparatus for communication with standard terminal equipment over a digital wireless link.
It is a further object of the present invention to provide a means of communicating time sensitive information over a variable time delay link.
SUMMARY OF THE INVENTION
The present invention is a novel apparatus and method of providing communications between standard unmodified terminal equipment over a 25 telephone link that includes a digital wireless link. The present invention eplaces the standard local modem with a mobile unit capable of digital communications and a base station comprising digital signal processing and a modem and capable o~ digital comrnunications. The functions of the original local modem are divided among the new elements.
One function of the new elements is to compensate for the time varying delay of the digital wireless link. The new elements recognize time sensitive messages, translate them into time insensitive messages indicating the time sensitive message for transmission over the wireless link. At the receiving end, the time insensitive messages are recognized 35 and the time sensitive messages reconstructed with the appropriate timing.
WO 95/14356 2 1 5 3 ~ 4 ~ PCT/us94/l309l BRIEF DESCRIPTION OF THE DRAWINGS
The features, objects, and advantages of the present invention will become more apparent from the detailed description set forth below when 5 taken in conjunction with the drawings in which like reference characters identify col~esl,ondingly throughout and wherein:
Figure 1 is an apparatus that uses standard telephone networks to convey data from one terminal to another;
Figure 2 is an apparatus that uses standard telephone networks and a 10 digital wireless link to convey data from one terminal to another;
Figure 3 is a detailed representation of an exemplary configuration of a mobile unit used to connect terminal equipment to a telephone network;
Figures 4A - 4C illustrate the transmission of five frames of data across a wireless link;
Figure 5 illustrates the issuance of a special time sensitive escape sequence; and Figure 6 is a detailed representation of a possible configuration of a base station and also illustrates several alternative configurations for connection to the telephone network.
DETAILED DESCRIPTION OF THE PREFERRED
EMBODIMENTS
Several methods exist today that use standard telephone networks to 25 convey data from one terminal to another. Terminals that connect by telephone networks can be FAX machines, personal computers, credit card veAfication machines, and telemetry devices. The standard connection of these type of devices is shown in Figure 1. For example assume terminal equipment 10 is transmitting information to terminal equipment 50.
30 Terminal equipment 10 produces digital data 110 representative of the information. Modem 20 converts digital data 110 to analog signal 120.
Analog signal 120 is of a proper bandwidth and power level to be transferable over standard telephone network 30. Telephone network 30 conveys analog signal 120 to its destination. The telephone network may 35 introduce noise such that output audible signal 130 is an estimate of analog signal 120. Modem 40 converts audible signal 130 to digital data 140 which is an estimate of digital data 110. Terminal equipment 50 receives digital data 140 and can act on an estimate of the information sent by terminal WO 95tl4356 PCI~/US94/13091 21~3148 4 equipment 10. Most such links are bi-directional with the reverse functions working in the same manner as the forward.
Figure 1 is a simplified diagram. Actual implementations of these connections can take on a variety of forms. For example in some S equipment, such as a standard FAX machines, the terminal equipment and the modem reside in the same housing. Also telephone network 30 may use any of a variety of methods well known in the art to convey analog signal 120 to its destination. Such methods may include digitizing the signal and transmitting the signal via satellite to a remote location where 10 audible signal 130 is created.
A wireless link is introduced into the configuration of Figure 1 when a user would like to connect his terminal equipment but does not have access to a land telephone network. The user may instead have a digital mobile communications device. Figure 2 is an exemplary embodiment of 15 such a configuration. In Figure 2, modem 20 has been replaced with mobile unit 60, wireless link 160, and digital signal processor (DSP) and modem 70.
DSP and modem 70 resides in base station 80 which could be a standard cellular or personal communications base station also capable of handling digital and analog voice communications. Figure 2 assumes that just one of 20 the connections has been replaced with a wireless link. The description that follows applies equally if communication is achieved with two wireless links.
Referring to Figure 2, assume again that terminal equipment 10 is transmitting information to terminal equipment 50. Terminal 25 equipment 10 produces digital dah 110 representative of the information.
Mobile unit 60 modulates digital data 110 and provides output over wireless link 160. The signal from wireless link 160 is received by base station 80 and DSP and modem 70. DSP and modem 70 converts the digital signal to analog signal 120 which is the same signal output by modem 20 in Figure 1.
30 Telephone network 30 conveys analog signal 120 to its destination.
Telephone network 30 may introduce noise such that output audible signal 130 is an estimate of analog signal 120. Modem 40 converts audible signal 130 to digital data 140 which is an estimate of digital data 110.
Terminal equipment 50 receives digital data 140 and can act on an estimate 35 of the information sent by terminal equipment 10. This link is bi-directional with the reverse functions working in the same manner as the forward.
Because in Figure 2 modem 20 has been replaced with mobile unit 60, wireless link 160, and DSP and modem 70, a new partitioning of the WO 95/14356 2 1 ~ 3 1 ~ ~ PCT/US94/13091 functions of modem 20 is necessary. In addition, some new commands and new functionality are necessary to use the wireless link. Ideally this new functionality should operate independent of the terminal equipment so that no modification of the terminal equipment is necessary to support the 5 wireless link. Figure 3 provides a more detailed representation of an exemplary configuration of mobile unit 60. In Figure 3, mobile unit 60 is assumed to be a mobile telephone that provides both voice and data capabilities. In an alternative embodiment, mobile unit 60 might be a dedicated single use mobile unit.
In Figure 3, digihl data 110 is connected to protocol stack 230 within mobile unit 60. Protocol stack 230 is capable of bi-directional communication with terminal equipment 10, mobile unit control processor 240 and radio modulator/demodulator 220. When protocol stack 230 receives digital data 110 for transmission over wireless link 160, it 15 provides any required encoding and passes the encoded information to radio modulator/demodulator 220 through switch 210. Radio modulator/demodulator 220 modulates the encoded information and provides the signal for transmission to wireless link 160. Inversely when a signal containing information for terminal equipment 10 arrives, radio 20 modulator/demodulator220 demodulates the signal and provides it to protocol stack 230 through switch 210.
Likewise when vocoder 200 receives analog information from speaker/microphone 260 for transmission over wireless link 160, it encodes the information and passes the encoded information to radio 25 modulator/demodulator 220 through switch 210. Radio modulator/demodulator 220 modulates the encoded information and provides the signal for transmission to wireless link 160. When a signal containing information for output on speaker/microphone 260 arrives on wireless link 160, modulator/demodulator 220 demodulates the signal and 30 provides it to vocoder 200 through switch 210. Vocoder 200 decodes the signal and provides audible output to speaker/microphone 260.
Mobile unit control processor 240 provides control over the functions of mobile unit 60. Information intended for mobile unit control processor 240 might come either over wireless link 160 or from digital 35 data 110. Protocol stack 230 directs information intended for mobile unit control processor 240 to it and receives commands and information for transmission from mobile unit control processor 240. Mobile unit control processor 240 also provides control functions for vocoder 200, switch 210 and radio modulator/demodulator 220.
WO 95114356 2 1 ~ 3 1 4 8 PCT/US94/13091 Protocol stack 230 provides the main control center for communication with terminal equipment 10 over the wireless link.
Protocol stack 230 must recognize and operate under a variety of protocols.
For instance, digital data 110 may use a different format or protocol from the 5 wireless link. Standard voice wireless connections do not provide the error free communication that is necessary for data transfer. Protocol stack 230 can provide a mechanism of error detection and error correction of both link directions.
Plolocol stack 230 may need to provide flow control. Digital data 110 10 may have a data rate that is higher than that of which wireless link 160 is capable. In this case protocol stack 230 may store the excess data and recall data at a rate a~E,rol,riate for output on the link. The inverse situation could also be true that wireless link 160 is capable of operating at a higher data rate than terminal equipment 10 is capable of receiving. Protocol 15 stack 230 may be capable of commanding the higher rate transmitting device to pause the flow of data.
Protocol stack 230 also packetizes and unpacketizes data. Typically digital data 110 provided by terminal equipment 10 is a steady stream of characters. Typically wireless link 160 is packetized meaning that certain bits 20 of information are grouped together for processing and transmission. A
group of data is called a frame. Frames aid in error detection and correction.
Protocol stack 230 must packetize digital data 110 provided by terminal equipment 10 into frames for radio modulator/demodulator 220 and unpacketize frames from radio modulator/demodulator 220 for digital 25 data 110.
r~olocol stack 230 must also recognize an array of special commands.
Referring again to Figures 1 and 2, terminal equipment 10 can produce several categories of output. Terminal equipment 10 can produce information for transfer to terminal equipment 50. Terminal equipment 10 30 can produce commands for modem 20 which are not to be transferred to terminal equipment 50. Terminal equipment 10 can also produce conunands for modem 40 which are not to be transferred to terminal equipment 50. Because in Figure 2, mo~len 20 of Figure 1 has been replaced with mobile unit 60, wireless link 160, and DSP and modem 70, if terminal 35 equipment sends a message intended for the local modem the message must be sent over wireless link 160. If the command intended for the local modem is related to a function now performed by protocol stack 230, protocol stack 230 must recognize and act upon the command with the aid of mobile unit control processor 240. Protocol stack 230 must autonomously WO 95/14356 2 1 ~ 3 1 4 8 PCT/US94113091 support these functions without additional direction from terminal equipment 10.
One of the challenges of the digital wireless link is that the time delay of the channel is variable. In a standard high capacity digital wireless link, 5 frame error rates of about 1% are co~ on. Using error detection methods, these errors can be correcled. One method to improve the resulting error rate is to provide a retransmission of lost or corrupted frames. Protocol stack 230 supports the retransmission of frames.
To illustrate the retran~micsiQn mechanism, refer again to Figure 3.
10 Assume that terminal equipment 10 issues a single command consisting of a stream of digital bits. In this example protocol stack 230 divides the digitalbits into five frames of data and passes the five frames to radio modulator/demodulator 220. Radio modulator/demodulator 220 modulates the data and sends the frames over wireless link 160. The 15 tra~smicsion of the five frames is illustrated in Figure 4A. Data stream 300 represents the five frames of data to be sent to DSP and modem 70. In Figure 4B, an estimate of data stream 300 has been received by DSP and mo~ 70 and has been recovered as data streams 305A and 305B. Within data stream 305B, frame four has been corrupted and DSP and modem 70 is 20 requesting that mobile unit 60 retransmit frame four. Figure 4C show the re-trallsmicsion of frame four. In Figure 4B notice that DSP and modem 70 outputs frames one, two, and three as audible signal 130 before the re-transmitted frame four is received thus introducing a substantial arbitrary delay between frame three and frame four. The co~les~onding 25 reverse mechanism works in the same manner. This entire process including packetization, flow control, and the transmission and retran~mission over the digital wireless link, is highly likely to destroy any timing relation between the data bits coming from terminal equipment 10.
Thus the time variable delay of the link must be overcome to support 30 reliable communications.
The destruction of the timing relationship between data bits coming from terminal equipment 10 can ~revent proper communication of time sensitive messages over the link. Standard time sensitive messages include escape, break, voice request for FAX, ring indications, result codes, 35 command termination, and data carrier detection. For example, a time sensitive message might follow a pattern such as one second where no input is made, three consecutive characters at a predetermined spacing, and then another second wherein no input is made. Typically such messages require timing with precision on the order of a millisecond. Using the example above, 0.99 seconds where no input is made, three consecutive characters at a predetermined spacing, and then another second wherein no input is made would not be recognized as the time sensitive command because 0.99 seconds is 10 milliseconds different than 1 second. The time 5 delay associated with the digital wireless link can exceed 10 milliseconds and thus destroy the information in a time sensitive message.
The present invention resolves Ws problem by using a special radio link protocol (RLP) to recognize the time sensitive messages. For example refe~ring again to Figure 3, assume a time sensitive message is received by 10 protocol stack 230 from digital data 110. Protocol stack 230 recognizes time sensitive messages and invokes the radio link protocol. Protocol stack 230, instead of repeating the time sensitive message to radio modulator/demodulator 220, translates the time sensitive message into a special message designating the type of time sensitive message received.
For example refer to Figure 5. In Figure 5, terminal equipment 10 has issued a special time sensitive escape sequence. The escape sequence is one second where no input is made, three consecutive "plus" characters at a predetermined spacing, and then another second wherein no input is made.
The escape sequence is used to alert the modem that a command or series of 20 commands from the terminal equipment is to follow. The commands are not intended for transfer as data to the receiving terminal equipment and instead are intended for action at the local or receiving modem. The local modem must recognize the escape sequence so that it does not erroneously pass the comm~nd as data. If the timing of the escape sequence is destroyed, 25 the modem will not recognize the escape sequence and the subsequent command.
In Figure 5, assume that the escape sequence is intend for transfer to the receiving mo-lPm Mobile unit 60 has recognized that a time sensitive message has been received and invoked the RLP. Within mobile unit 60, 30 protocol stack 230 translates the time sensitive message into a time insensitive message designating the time sensitive message received. The time insensitive translation, in this case "escape sequence issued," is transmitted over wireless link 160. At base station 80 the time insensitive translation is recognized and reconstructed with the proper timing for 35 transmission as analog signal 120 for action at modem 40. Alternatively if the escape sequence is solely intended for action by DSP and modem 70, DSP
and modem 70 may act upon the mess~ge and refrain from re-transmission of the regenerated sequence over analog signal 120. This function operates WO 95/14356 2 ~ ~ 3 1 4 ~ PCI~/US94/13091 bi-directionally with the reverse function working in the same manner as the forward.
Base station 80 and DSP and modem 70 provide similar functions to those found in mobile unit 60. Base station 80 receives and provides the 5 radio link signal over wireless link 160 and analog telephone network signal 120 while mobile unit 60 receives and provides radio link signal and terminal equipment signal, digital data 110.
Figure 6 illustrates in more detail base station 80. Figure 6 also illustrates several alternative configurations to the standard configuration 10 discussed thus far. In Figure 6, DSP and modem 70 is made up of four parts:
radio modulator/demodulator 72, radio link protocol 74, protocol stack 76, and modem 78. Radio modulator/demodulator 72 demodulates the incoming signal from wireless link 160 and provides the signal to radio link protocol 74. Radio modulator/-lPrno lulator 72 also modulates the outgoing 15 signal from radio link protocol 74 and provides it to wireless link 160.
Together radio link protocol 74 and protocol stack 76 performs similar functions to that of protocol stack 230 in mobile unit 60. Radio link protocol 74 provides functions for wireless link 160 such as supporting re-transmissions for error free communication as discussed in conjunction 20 with Figure 4.
Protocol stack 76 provides the recognition, packetization, transfer, or translation of commands from modem 78. For example protocol stack 76 translates any time sensitive mess~ges received from modem 78. Protocol stack 76 provides the depacketization, recognition, transfer, or translation of 25 mess~es to modem 78 including the recognition and reconstruction of time sensitive messages. Digital data 111 is analogous to digital data 110.
Modem 78 receives and produces digital data 111 and communicates analog signal 120 to and from telephone network 30.
The partitioning of DSP and modem 70 shown in Figure 6 enables a 30 variety of alternative configurations for the base station. The packetized data 355 between radio link protocol 74 and protocol stack 76 is encoded for transmission over the wireless link and is error free in both directions.
Packetized data 355 is encoded for transfer over a time variable channel thus if the base station is part of a public network, packetized data 355 may be 35 suitable for direct communication over the network. For example, packetized data 355 can be connected to gateway 375 which provides connection to public packet switched network 380. Generally packet switched networks also have path delays that are time varying. Thus the configuration makes good use of the encoded time sensitive messages.
WO 95/14356 2 1 53 1 4 8 PCTtUS94/13091 Protocol stack 390 performs the same functions protocol stack 76 including the recognition and translation of time sensitive message into time insensitive commands and the recognition and reconstruction time insensitive mess~es into time sensitive messages. Host 400 may be variety 5 of devices including a server computer, a bulletin board or a modem network.
If the base station is part of a private network, packetized data 355 may be directly communicated on private packet switched network 360 again making good use of the encoded time sensitive messages. Protocol stack 390 10 performs the same functions as protocol stack 76. Likewise modem 370 provides the same functions as modem 78.
A fourth possible connection communicates digital data 111 to remote modem 350. Remote modem 350 provides the same functions as modem 78 but may not be located within base station 80. This configuration 15 might be used if the data serviced provider and the wireless service provider are di~rerent entities.
The previous description of the ~refelred embodiments is provided to enable any person skilled in the art to make or use the present invention.
The various modiffcations to these emborliments will be readily apparent to 20 those skilled in the art, and the generic principles defined herein may be applied to other embodiments without the use of the inventive faculty.
Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
WE CLAIM:
MESSAGE OVER A VARL~ E DELAY CHANNEL
BACKGROUND OF THE INVENTION
I. Field of the Invention The present invention relates to communication. More particularly, the present invention relates to a novel and improved method and 10 apparatus for providing communication over a digital link.
II. Description of the Related Art A variety of apparatus exists today that use standard telephone 15 networks to convey data from one terminal to another. One of th~ most coIrunon terminals that uses a standard te~ephone network to convey data is the facsimile (FAX) machine. Like other terminal equipment that use standard telephone networks, a FAX machine uses a modem to translate digital information to audible analog tones for transmission over the 20 telephone networlc. At the receiving PAX machine, a modem is used to convert the tones Dack into an estimate of the original digital information sent by the transmitting FAX machin~.
With the deployment of cellular and personal communications wireless systems, the end ~ser may wish to connect his terminal equipment 25 to a mobile communications device instead of directly to a land telephone network. However, if the user attempts to send the audible tones produced by a modem over a standard analog FM cellular channel, it is doubtful that he will be successful. In general, the FM cellular channel introduces a substantial amount of noise into the link compared to the standard land 30 telephone network. The additional noise translates into errors in the estimation of the digital information wn~n the signal is converted at the receiving end. The errors on the link can be overcome by constraining communications to very low transmission rates.
If the end user attempts to send the audible tones produced by a 35 modem over a standard digital wireless channel, it is also doubtful that he will be successful. Digital wireless communication equipment typically uses vocoders to convert incoming voice signals into digital bits for transmission over the channel. Vocoders are tailored to sample and compress human voice. Because modem tones differ significantly from human voice, the 40 vocoder can cause noticeable degradation to the modem tones. Also, 2 1 ~ 3 ~ 4 8 PCT/US94113091 maximizing the capacity of the system in terms of the number of simultaneous users that can be handled is extremely important in a system using a wireless link. Digitizing modem tones with a vocoder and sending them over the digital wireless link is an ineffic ellt use of the radio channel..7 A more efficient, flexible, and reliable transmission means is to provide a mechanism to transmit the digital data over the digital wireless link directly. This configuration presents some unique opportunities to take advantage of the digital link to provide high quality service.
A typical digital wireless link is not an error free channel. To provide 1~ error free communication, the wireless link protocol may provide re-transmission of lost or corrupted data. The re-transmissions introduce arbitrary and significant delays in the data. When the time sensitive messages are transmitted over the wireless link, the timing of the signals may be lost thus prohibiting proper communications.
It is therefore the object of the present invention to provide an efficient method and apparatus for communication with standard terminal equipment over a digital wireless link.
It is a further object of the present invention to provide a means of communicating time sensitive information over a variable time delay link.
SUMMARY OF THE INVENTION
The present invention is a novel apparatus and method of providing communications between standard unmodified terminal equipment over a 25 telephone link that includes a digital wireless link. The present invention eplaces the standard local modem with a mobile unit capable of digital communications and a base station comprising digital signal processing and a modem and capable o~ digital comrnunications. The functions of the original local modem are divided among the new elements.
One function of the new elements is to compensate for the time varying delay of the digital wireless link. The new elements recognize time sensitive messages, translate them into time insensitive messages indicating the time sensitive message for transmission over the wireless link. At the receiving end, the time insensitive messages are recognized 35 and the time sensitive messages reconstructed with the appropriate timing.
WO 95/14356 2 1 5 3 ~ 4 ~ PCT/us94/l309l BRIEF DESCRIPTION OF THE DRAWINGS
The features, objects, and advantages of the present invention will become more apparent from the detailed description set forth below when 5 taken in conjunction with the drawings in which like reference characters identify col~esl,ondingly throughout and wherein:
Figure 1 is an apparatus that uses standard telephone networks to convey data from one terminal to another;
Figure 2 is an apparatus that uses standard telephone networks and a 10 digital wireless link to convey data from one terminal to another;
Figure 3 is a detailed representation of an exemplary configuration of a mobile unit used to connect terminal equipment to a telephone network;
Figures 4A - 4C illustrate the transmission of five frames of data across a wireless link;
Figure 5 illustrates the issuance of a special time sensitive escape sequence; and Figure 6 is a detailed representation of a possible configuration of a base station and also illustrates several alternative configurations for connection to the telephone network.
DETAILED DESCRIPTION OF THE PREFERRED
EMBODIMENTS
Several methods exist today that use standard telephone networks to 25 convey data from one terminal to another. Terminals that connect by telephone networks can be FAX machines, personal computers, credit card veAfication machines, and telemetry devices. The standard connection of these type of devices is shown in Figure 1. For example assume terminal equipment 10 is transmitting information to terminal equipment 50.
30 Terminal equipment 10 produces digital data 110 representative of the information. Modem 20 converts digital data 110 to analog signal 120.
Analog signal 120 is of a proper bandwidth and power level to be transferable over standard telephone network 30. Telephone network 30 conveys analog signal 120 to its destination. The telephone network may 35 introduce noise such that output audible signal 130 is an estimate of analog signal 120. Modem 40 converts audible signal 130 to digital data 140 which is an estimate of digital data 110. Terminal equipment 50 receives digital data 140 and can act on an estimate of the information sent by terminal WO 95tl4356 PCI~/US94/13091 21~3148 4 equipment 10. Most such links are bi-directional with the reverse functions working in the same manner as the forward.
Figure 1 is a simplified diagram. Actual implementations of these connections can take on a variety of forms. For example in some S equipment, such as a standard FAX machines, the terminal equipment and the modem reside in the same housing. Also telephone network 30 may use any of a variety of methods well known in the art to convey analog signal 120 to its destination. Such methods may include digitizing the signal and transmitting the signal via satellite to a remote location where 10 audible signal 130 is created.
A wireless link is introduced into the configuration of Figure 1 when a user would like to connect his terminal equipment but does not have access to a land telephone network. The user may instead have a digital mobile communications device. Figure 2 is an exemplary embodiment of 15 such a configuration. In Figure 2, modem 20 has been replaced with mobile unit 60, wireless link 160, and digital signal processor (DSP) and modem 70.
DSP and modem 70 resides in base station 80 which could be a standard cellular or personal communications base station also capable of handling digital and analog voice communications. Figure 2 assumes that just one of 20 the connections has been replaced with a wireless link. The description that follows applies equally if communication is achieved with two wireless links.
Referring to Figure 2, assume again that terminal equipment 10 is transmitting information to terminal equipment 50. Terminal 25 equipment 10 produces digital dah 110 representative of the information.
Mobile unit 60 modulates digital data 110 and provides output over wireless link 160. The signal from wireless link 160 is received by base station 80 and DSP and modem 70. DSP and modem 70 converts the digital signal to analog signal 120 which is the same signal output by modem 20 in Figure 1.
30 Telephone network 30 conveys analog signal 120 to its destination.
Telephone network 30 may introduce noise such that output audible signal 130 is an estimate of analog signal 120. Modem 40 converts audible signal 130 to digital data 140 which is an estimate of digital data 110.
Terminal equipment 50 receives digital data 140 and can act on an estimate 35 of the information sent by terminal equipment 10. This link is bi-directional with the reverse functions working in the same manner as the forward.
Because in Figure 2 modem 20 has been replaced with mobile unit 60, wireless link 160, and DSP and modem 70, a new partitioning of the WO 95/14356 2 1 ~ 3 1 ~ ~ PCT/US94/13091 functions of modem 20 is necessary. In addition, some new commands and new functionality are necessary to use the wireless link. Ideally this new functionality should operate independent of the terminal equipment so that no modification of the terminal equipment is necessary to support the 5 wireless link. Figure 3 provides a more detailed representation of an exemplary configuration of mobile unit 60. In Figure 3, mobile unit 60 is assumed to be a mobile telephone that provides both voice and data capabilities. In an alternative embodiment, mobile unit 60 might be a dedicated single use mobile unit.
In Figure 3, digihl data 110 is connected to protocol stack 230 within mobile unit 60. Protocol stack 230 is capable of bi-directional communication with terminal equipment 10, mobile unit control processor 240 and radio modulator/demodulator 220. When protocol stack 230 receives digital data 110 for transmission over wireless link 160, it 15 provides any required encoding and passes the encoded information to radio modulator/demodulator 220 through switch 210. Radio modulator/demodulator 220 modulates the encoded information and provides the signal for transmission to wireless link 160. Inversely when a signal containing information for terminal equipment 10 arrives, radio 20 modulator/demodulator220 demodulates the signal and provides it to protocol stack 230 through switch 210.
Likewise when vocoder 200 receives analog information from speaker/microphone 260 for transmission over wireless link 160, it encodes the information and passes the encoded information to radio 25 modulator/demodulator 220 through switch 210. Radio modulator/demodulator 220 modulates the encoded information and provides the signal for transmission to wireless link 160. When a signal containing information for output on speaker/microphone 260 arrives on wireless link 160, modulator/demodulator 220 demodulates the signal and 30 provides it to vocoder 200 through switch 210. Vocoder 200 decodes the signal and provides audible output to speaker/microphone 260.
Mobile unit control processor 240 provides control over the functions of mobile unit 60. Information intended for mobile unit control processor 240 might come either over wireless link 160 or from digital 35 data 110. Protocol stack 230 directs information intended for mobile unit control processor 240 to it and receives commands and information for transmission from mobile unit control processor 240. Mobile unit control processor 240 also provides control functions for vocoder 200, switch 210 and radio modulator/demodulator 220.
WO 95114356 2 1 ~ 3 1 4 8 PCT/US94/13091 Protocol stack 230 provides the main control center for communication with terminal equipment 10 over the wireless link.
Protocol stack 230 must recognize and operate under a variety of protocols.
For instance, digital data 110 may use a different format or protocol from the 5 wireless link. Standard voice wireless connections do not provide the error free communication that is necessary for data transfer. Protocol stack 230 can provide a mechanism of error detection and error correction of both link directions.
Plolocol stack 230 may need to provide flow control. Digital data 110 10 may have a data rate that is higher than that of which wireless link 160 is capable. In this case protocol stack 230 may store the excess data and recall data at a rate a~E,rol,riate for output on the link. The inverse situation could also be true that wireless link 160 is capable of operating at a higher data rate than terminal equipment 10 is capable of receiving. Protocol 15 stack 230 may be capable of commanding the higher rate transmitting device to pause the flow of data.
Protocol stack 230 also packetizes and unpacketizes data. Typically digital data 110 provided by terminal equipment 10 is a steady stream of characters. Typically wireless link 160 is packetized meaning that certain bits 20 of information are grouped together for processing and transmission. A
group of data is called a frame. Frames aid in error detection and correction.
Protocol stack 230 must packetize digital data 110 provided by terminal equipment 10 into frames for radio modulator/demodulator 220 and unpacketize frames from radio modulator/demodulator 220 for digital 25 data 110.
r~olocol stack 230 must also recognize an array of special commands.
Referring again to Figures 1 and 2, terminal equipment 10 can produce several categories of output. Terminal equipment 10 can produce information for transfer to terminal equipment 50. Terminal equipment 10 30 can produce commands for modem 20 which are not to be transferred to terminal equipment 50. Terminal equipment 10 can also produce conunands for modem 40 which are not to be transferred to terminal equipment 50. Because in Figure 2, mo~len 20 of Figure 1 has been replaced with mobile unit 60, wireless link 160, and DSP and modem 70, if terminal 35 equipment sends a message intended for the local modem the message must be sent over wireless link 160. If the command intended for the local modem is related to a function now performed by protocol stack 230, protocol stack 230 must recognize and act upon the command with the aid of mobile unit control processor 240. Protocol stack 230 must autonomously WO 95/14356 2 1 ~ 3 1 4 8 PCT/US94113091 support these functions without additional direction from terminal equipment 10.
One of the challenges of the digital wireless link is that the time delay of the channel is variable. In a standard high capacity digital wireless link, 5 frame error rates of about 1% are co~ on. Using error detection methods, these errors can be correcled. One method to improve the resulting error rate is to provide a retransmission of lost or corrupted frames. Protocol stack 230 supports the retransmission of frames.
To illustrate the retran~micsiQn mechanism, refer again to Figure 3.
10 Assume that terminal equipment 10 issues a single command consisting of a stream of digital bits. In this example protocol stack 230 divides the digitalbits into five frames of data and passes the five frames to radio modulator/demodulator 220. Radio modulator/demodulator 220 modulates the data and sends the frames over wireless link 160. The 15 tra~smicsion of the five frames is illustrated in Figure 4A. Data stream 300 represents the five frames of data to be sent to DSP and modem 70. In Figure 4B, an estimate of data stream 300 has been received by DSP and mo~ 70 and has been recovered as data streams 305A and 305B. Within data stream 305B, frame four has been corrupted and DSP and modem 70 is 20 requesting that mobile unit 60 retransmit frame four. Figure 4C show the re-trallsmicsion of frame four. In Figure 4B notice that DSP and modem 70 outputs frames one, two, and three as audible signal 130 before the re-transmitted frame four is received thus introducing a substantial arbitrary delay between frame three and frame four. The co~les~onding 25 reverse mechanism works in the same manner. This entire process including packetization, flow control, and the transmission and retran~mission over the digital wireless link, is highly likely to destroy any timing relation between the data bits coming from terminal equipment 10.
Thus the time variable delay of the link must be overcome to support 30 reliable communications.
The destruction of the timing relationship between data bits coming from terminal equipment 10 can ~revent proper communication of time sensitive messages over the link. Standard time sensitive messages include escape, break, voice request for FAX, ring indications, result codes, 35 command termination, and data carrier detection. For example, a time sensitive message might follow a pattern such as one second where no input is made, three consecutive characters at a predetermined spacing, and then another second wherein no input is made. Typically such messages require timing with precision on the order of a millisecond. Using the example above, 0.99 seconds where no input is made, three consecutive characters at a predetermined spacing, and then another second wherein no input is made would not be recognized as the time sensitive command because 0.99 seconds is 10 milliseconds different than 1 second. The time 5 delay associated with the digital wireless link can exceed 10 milliseconds and thus destroy the information in a time sensitive message.
The present invention resolves Ws problem by using a special radio link protocol (RLP) to recognize the time sensitive messages. For example refe~ring again to Figure 3, assume a time sensitive message is received by 10 protocol stack 230 from digital data 110. Protocol stack 230 recognizes time sensitive messages and invokes the radio link protocol. Protocol stack 230, instead of repeating the time sensitive message to radio modulator/demodulator 220, translates the time sensitive message into a special message designating the type of time sensitive message received.
For example refer to Figure 5. In Figure 5, terminal equipment 10 has issued a special time sensitive escape sequence. The escape sequence is one second where no input is made, three consecutive "plus" characters at a predetermined spacing, and then another second wherein no input is made.
The escape sequence is used to alert the modem that a command or series of 20 commands from the terminal equipment is to follow. The commands are not intended for transfer as data to the receiving terminal equipment and instead are intended for action at the local or receiving modem. The local modem must recognize the escape sequence so that it does not erroneously pass the comm~nd as data. If the timing of the escape sequence is destroyed, 25 the modem will not recognize the escape sequence and the subsequent command.
In Figure 5, assume that the escape sequence is intend for transfer to the receiving mo-lPm Mobile unit 60 has recognized that a time sensitive message has been received and invoked the RLP. Within mobile unit 60, 30 protocol stack 230 translates the time sensitive message into a time insensitive message designating the time sensitive message received. The time insensitive translation, in this case "escape sequence issued," is transmitted over wireless link 160. At base station 80 the time insensitive translation is recognized and reconstructed with the proper timing for 35 transmission as analog signal 120 for action at modem 40. Alternatively if the escape sequence is solely intended for action by DSP and modem 70, DSP
and modem 70 may act upon the mess~ge and refrain from re-transmission of the regenerated sequence over analog signal 120. This function operates WO 95/14356 2 ~ ~ 3 1 4 ~ PCI~/US94/13091 bi-directionally with the reverse function working in the same manner as the forward.
Base station 80 and DSP and modem 70 provide similar functions to those found in mobile unit 60. Base station 80 receives and provides the 5 radio link signal over wireless link 160 and analog telephone network signal 120 while mobile unit 60 receives and provides radio link signal and terminal equipment signal, digital data 110.
Figure 6 illustrates in more detail base station 80. Figure 6 also illustrates several alternative configurations to the standard configuration 10 discussed thus far. In Figure 6, DSP and modem 70 is made up of four parts:
radio modulator/demodulator 72, radio link protocol 74, protocol stack 76, and modem 78. Radio modulator/demodulator 72 demodulates the incoming signal from wireless link 160 and provides the signal to radio link protocol 74. Radio modulator/-lPrno lulator 72 also modulates the outgoing 15 signal from radio link protocol 74 and provides it to wireless link 160.
Together radio link protocol 74 and protocol stack 76 performs similar functions to that of protocol stack 230 in mobile unit 60. Radio link protocol 74 provides functions for wireless link 160 such as supporting re-transmissions for error free communication as discussed in conjunction 20 with Figure 4.
Protocol stack 76 provides the recognition, packetization, transfer, or translation of commands from modem 78. For example protocol stack 76 translates any time sensitive mess~ges received from modem 78. Protocol stack 76 provides the depacketization, recognition, transfer, or translation of 25 mess~es to modem 78 including the recognition and reconstruction of time sensitive messages. Digital data 111 is analogous to digital data 110.
Modem 78 receives and produces digital data 111 and communicates analog signal 120 to and from telephone network 30.
The partitioning of DSP and modem 70 shown in Figure 6 enables a 30 variety of alternative configurations for the base station. The packetized data 355 between radio link protocol 74 and protocol stack 76 is encoded for transmission over the wireless link and is error free in both directions.
Packetized data 355 is encoded for transfer over a time variable channel thus if the base station is part of a public network, packetized data 355 may be 35 suitable for direct communication over the network. For example, packetized data 355 can be connected to gateway 375 which provides connection to public packet switched network 380. Generally packet switched networks also have path delays that are time varying. Thus the configuration makes good use of the encoded time sensitive messages.
WO 95/14356 2 1 53 1 4 8 PCTtUS94/13091 Protocol stack 390 performs the same functions protocol stack 76 including the recognition and translation of time sensitive message into time insensitive commands and the recognition and reconstruction time insensitive mess~es into time sensitive messages. Host 400 may be variety 5 of devices including a server computer, a bulletin board or a modem network.
If the base station is part of a private network, packetized data 355 may be directly communicated on private packet switched network 360 again making good use of the encoded time sensitive messages. Protocol stack 390 10 performs the same functions as protocol stack 76. Likewise modem 370 provides the same functions as modem 78.
A fourth possible connection communicates digital data 111 to remote modem 350. Remote modem 350 provides the same functions as modem 78 but may not be located within base station 80. This configuration 15 might be used if the data serviced provider and the wireless service provider are di~rerent entities.
The previous description of the ~refelred embodiments is provided to enable any person skilled in the art to make or use the present invention.
The various modiffcations to these emborliments will be readily apparent to 20 those skilled in the art, and the generic principles defined herein may be applied to other embodiments without the use of the inventive faculty.
Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
WE CLAIM:
Claims (9)
1. A method of communicating between a first terminal equipment unit and a second terminal equipment unit using a mobile unit and a base station each capable of digital communications, said first terminal equipment unit producing digital data intended for said second terminal equipment unit, comprising the steps of:
receiving at said mobile unit said digital data from said first terminal equipment unit;
packetizing at said mobile unit said digital data from said first terminal equipment unit;
modulating at said mobile unit said packetized digital data;
transmitting from said mobile unit said modulated packetized digital data on a wireless link;
receiving at said base station said transmitted modulated packetized digital data;
demodulating at said base station said received modulated packetized digital data to produce an copy of said packetized digital data converting at said base station said copy of said packetized digital data to a plurality of analog tones;
transmitting said stream of analog tones over a telephone network;
receiving at a remote modem said stream of analog tones;
converting at said remote modem said stream of analog tones to a copy of said digital data; and providing from said remote modem said copy of said digital data to said second terminal equipment unit.
receiving at said mobile unit said digital data from said first terminal equipment unit;
packetizing at said mobile unit said digital data from said first terminal equipment unit;
modulating at said mobile unit said packetized digital data;
transmitting from said mobile unit said modulated packetized digital data on a wireless link;
receiving at said base station said transmitted modulated packetized digital data;
demodulating at said base station said received modulated packetized digital data to produce an copy of said packetized digital data converting at said base station said copy of said packetized digital data to a plurality of analog tones;
transmitting said stream of analog tones over a telephone network;
receiving at a remote modem said stream of analog tones;
converting at said remote modem said stream of analog tones to a copy of said digital data; and providing from said remote modem said copy of said digital data to said second terminal equipment unit.
2. The method of claim 1 wherein said step of transmitting said modulated packetized digital data on said wireless link introduces a delay in said received modulated packetized digital data and wherein said delay has a value that depends on the time of transmission.
3. The method of claim 2 wherein said step of packetizing said digital data further comprises the steps of:
recognizing a message having a fixed timing within said digital data wherein said fixed timing of said message conveys information; and converting said message into a representative message having a unessential timing comprising said information wherein said unessential timing of said representative message conveys no information.
recognizing a message having a fixed timing within said digital data wherein said fixed timing of said message conveys information; and converting said message into a representative message having a unessential timing comprising said information wherein said unessential timing of said representative message conveys no information.
4. A telephone modem apparatus having a wireless link, comprising:
a mobile unit for receiving a stream of standard digital data from a terminal equipment unit and for transmitting an information signal; and a wireless link for conveying said information signal;
a base station for receiving said information signal and providing analog tones comprising:
a digital signal processor for receiving said information signal and for providing a copy of said stream of standard digital data; and a modem for receiving said stream of standard digital data and providing said analog tones.
a mobile unit for receiving a stream of standard digital data from a terminal equipment unit and for transmitting an information signal; and a wireless link for conveying said information signal;
a base station for receiving said information signal and providing analog tones comprising:
a digital signal processor for receiving said information signal and for providing a copy of said stream of standard digital data; and a modem for receiving said stream of standard digital data and providing said analog tones.
5. The apparatus of claim 4 wherein said modem is also for receiving an input analog signal and providing an second stream of standard digital data, wherein said digital signal processor is also for receiving said second stream of standard digital data and for transmitting a reverse information signal, wherein said wireless link is for conveying said reverse information signal, and wherein said mobile unit is also for receiving said reverse information signal and for providing a copy of said second stream of standard digital data.
6. The apparatus of claim 4 wherein said mobile unit comprises:
a protocol stack for receiving said stream of standard digital data and providing a set of data packets; and a radio modulator for receiving said set of data packets and for providing said information signal.
a protocol stack for receiving said stream of standard digital data and providing a set of data packets; and a radio modulator for receiving said set of data packets and for providing said information signal.
7. The apparatus of claim 4 wherein said protocol stack is further for recognizing a time sensitive message in said stream of standard digital data, and for encoding said time sensitive message into a corresponding time insensitive message and providing said corresponding time insensitive message within said set of data packets.
8. The apparatus of claims 5 wherein said digital signal processor is further for recognizing said corresponding time insensitive message and reconstructing said time sensitive message and providing said time sensitive within said copy of said stream of standard digital data.
9. A method of providing time sensitive messaging over a variable time delay channel, comprising the steps of:
recognizing a time sensitive message within a set of messages;
encoding said time sensitive message into an encoded representative message wherein said encoded representative message is time insensitive;
conveying said encoded representative message though said variable time delay channel;
recognizing said encoded representative message output from said variable time delay channel; and reconstructing said time sensitive message.
recognizing a time sensitive message within a set of messages;
encoding said time sensitive message into an encoded representative message wherein said encoded representative message is time insensitive;
conveying said encoded representative message though said variable time delay channel;
recognizing said encoded representative message output from said variable time delay channel; and reconstructing said time sensitive message.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US152,158 | 1993-11-15 | ||
US08/152,158 US5479475A (en) | 1993-11-15 | 1993-11-15 | Method and system for providing communication between standard terminal equipment using a remote communication unit |
PCT/US1994/013091 WO1995014356A2 (en) | 1993-11-15 | 1994-11-14 | Method and apparatus of providing time sensitive message over a variable delay channel |
Publications (1)
Publication Number | Publication Date |
---|---|
CA2153148A1 true CA2153148A1 (en) | 1995-05-26 |
Family
ID=22541729
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CA002153148A Abandoned CA2153148A1 (en) | 1993-11-15 | 1994-11-14 | Method and apparatus of providing time sensitive message over a variable delay channel |
Country Status (14)
Country | Link |
---|---|
US (2) | US5479475A (en) |
EP (1) | EP0679323B1 (en) |
JP (1) | JP3351533B2 (en) |
KR (1) | KR100362456B1 (en) |
CN (1) | CN1130086C (en) |
AT (1) | ATE301908T1 (en) |
AU (1) | AU683706B2 (en) |
BR (1) | BR9405750A (en) |
CA (1) | CA2153148A1 (en) |
DE (1) | DE69434451T2 (en) |
FI (3) | FI114073B (en) |
HK (1) | HK1015217A1 (en) |
RU (1) | RU2225683C2 (en) |
WO (1) | WO1995014356A2 (en) |
Families Citing this family (69)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5864560A (en) | 1993-01-08 | 1999-01-26 | Multi-Tech Systems, Inc. | Method and apparatus for mode switching in a voice over data computer-based personal communications system |
US5452289A (en) | 1993-01-08 | 1995-09-19 | Multi-Tech Systems, Inc. | Computer-based multifunction personal communications system |
US5535204A (en) | 1993-01-08 | 1996-07-09 | Multi-Tech Systems, Inc. | Ringdown and ringback signalling for a computer-based multifunction personal communications system |
US6009082A (en) | 1993-01-08 | 1999-12-28 | Multi-Tech Systems, Inc. | Computer-based multifunction personal communication system with caller ID |
US5812534A (en) | 1993-01-08 | 1998-09-22 | Multi-Tech Systems, Inc. | Voice over data conferencing for a computer-based personal communications system |
US5757801A (en) | 1994-04-19 | 1998-05-26 | Multi-Tech Systems, Inc. | Advanced priority statistical multiplexer |
US5682386A (en) | 1994-04-19 | 1997-10-28 | Multi-Tech Systems, Inc. | Data/voice/fax compression multiplexer |
CA2148179A1 (en) | 1994-05-13 | 1995-11-14 | Said S. Saadeh | Cordless modem system having multiple base and remote stations which are interusable and secure |
GB2301987B (en) * | 1995-06-05 | 2000-01-12 | Nokia Mobile Phones Ltd | Radio telephone text transmission system |
ZA965340B (en) | 1995-06-30 | 1997-01-27 | Interdigital Tech Corp | Code division multiple access (cdma) communication system |
GB2306854B (en) * | 1995-10-20 | 1998-04-08 | At & T Corp | Apparatus for radio local loop system |
US6029072A (en) * | 1996-01-25 | 2000-02-22 | Oki Telecom, Inc. | Portable telephone with terminal mode facility |
DE19640220A1 (en) * | 1996-01-31 | 1997-08-07 | Siemens Ag | DECT cordless communication system with protocol-evaluating base stations |
US5889816A (en) * | 1996-02-02 | 1999-03-30 | Lucent Technologies, Inc. | Wireless adapter architecture for mobile computing |
US8117298B1 (en) | 1996-02-26 | 2012-02-14 | Graphon Corporation | Multi-homed web server |
US5884187A (en) | 1996-03-13 | 1999-03-16 | Ziv; Noam A. | Method and apparatus for providing centralized power control administration for a set of base stations |
US5995547A (en) * | 1996-11-26 | 1999-11-30 | Ericsson Inc. | Method and apparatus for mapping between cellular bit streams and wireline waveforms |
FR2760920B1 (en) * | 1997-03-12 | 2000-08-04 | Sagem | METHOD FOR TRANSMITTING DATA BETWEEN DATA PROCESSING MEANS AND A RADIO COMMUNICATION NETWORK AND MOBILE MODULE AND TERMINAL FOR IMPLEMENTING THE METHOD |
WO1998053573A2 (en) * | 1997-05-19 | 1998-11-26 | Integrated Data Communications, Inc. | System and method to communicate time stamped, 3-axis geo-position data within telecommunication networks |
US6690681B1 (en) * | 1997-05-19 | 2004-02-10 | Airbiquity Inc. | In-band signaling for data communications over digital wireless telecommunications network |
US6493338B1 (en) * | 1997-05-19 | 2002-12-10 | Airbiquity Inc. | Multichannel in-band signaling for data communications over digital wireless telecommunications networks |
US6026292A (en) * | 1997-08-19 | 2000-02-15 | Qualcomm Incorporated | Truck communication system |
US5991615A (en) * | 1997-08-18 | 1999-11-23 | Transcommunications, Inc. | Truck communication system |
US6434125B1 (en) * | 1997-10-24 | 2002-08-13 | Lucent Technologies Inc. | Automatic data service selection method and apparatus for digital wireless communication networks |
US6976080B1 (en) * | 1998-03-27 | 2005-12-13 | Hewlett-Packard Development Company, L.P. | Multiple-protocol communication subsystem controller |
US6765901B1 (en) | 1998-06-11 | 2004-07-20 | Nvidia Corporation | TCP/IP/PPP modem |
US6201827B1 (en) | 1998-09-09 | 2001-03-13 | Qualcomm Incorporated | System and method for probability based lock detection |
US6229841B1 (en) | 1998-12-11 | 2001-05-08 | Qualcomm Incorporated | Method and apparatus for energy estimation in a wireless receiver capable of receiving multiple instances of a common signal |
US6130923A (en) * | 1998-12-11 | 2000-10-10 | Qualcomm Incorporated | Lock detection for multipath wireless receiver |
US6353748B1 (en) | 1999-05-18 | 2002-03-05 | Semax Wireless, Inc. | Digital wireless local loop fax/data interface |
KR100414367B1 (en) * | 1999-12-29 | 2004-01-07 | 엘지전자 주식회사 | Apparatus and method for detecting data conversion error in mobile switching system |
US6591114B1 (en) | 2000-02-24 | 2003-07-08 | Qualicom Systems, Inc. | Fixed cellular communications system |
US6794457B2 (en) * | 2001-04-30 | 2004-09-21 | 3M Innovative Properties Company | Fluoropolymer curing system containing a nitrogen cure site monomer |
US7215965B2 (en) * | 2001-11-01 | 2007-05-08 | Airbiquity Inc. | Facility and method for wireless transmission of location data in a voice channel of a digital wireless telecommunications network |
US6895474B2 (en) * | 2002-04-29 | 2005-05-17 | Micron Technology, Inc. | Synchronous DRAM with selectable internal prefetch size |
US7151949B2 (en) * | 2003-07-09 | 2006-12-19 | Lexmark International, Inc. | Wireless facsimile adapter and system for printer and all-in-one devices and methods using the same |
US8606590B2 (en) * | 2004-12-22 | 2013-12-10 | At&T Intellectual Property I, L.P. | Methods, systems, and computer program products for providing personalized, just-in-time information services |
US7508810B2 (en) | 2005-01-31 | 2009-03-24 | Airbiquity Inc. | Voice channel control of wireless packet data communications |
US8920343B2 (en) | 2006-03-23 | 2014-12-30 | Michael Edward Sabatino | Apparatus for acquiring and processing of physiological auditory signals |
US7924934B2 (en) * | 2006-04-07 | 2011-04-12 | Airbiquity, Inc. | Time diversity voice channel data communications |
US7657286B2 (en) * | 2006-05-11 | 2010-02-02 | Nokia Corporation | Multiradio control interface element in modem |
US7664532B2 (en) * | 2006-06-02 | 2010-02-16 | Nokia Corporation | Radio transmission scheduling according to multiradio control in a radio modem |
US7949364B2 (en) * | 2006-10-03 | 2011-05-24 | Nokia Corporation | System for managing radio modems |
US7827245B2 (en) * | 2007-03-06 | 2010-11-02 | International Business Machines Corporation | Methods and computer program products for securing display of message content |
US20080291830A1 (en) * | 2007-05-25 | 2008-11-27 | Nokia Corporation | Multiradio control incorporating quality of service |
US7979095B2 (en) | 2007-10-20 | 2011-07-12 | Airbiquity, Inc. | Wireless in-band signaling with in-vehicle systems |
US8958441B2 (en) | 2008-06-05 | 2015-02-17 | Qualcomm Incorporated | System and method of an in-band modem for data communications over digital wireless communication networks |
US8503517B2 (en) * | 2008-06-05 | 2013-08-06 | Qualcomm Incorporated | System and method of an in-band modem for data communications over digital wireless communication networks |
US8725502B2 (en) * | 2008-06-05 | 2014-05-13 | Qualcomm Incorporated | System and method of an in-band modem for data communications over digital wireless communication networks |
US8825480B2 (en) * | 2008-06-05 | 2014-09-02 | Qualcomm Incorporated | Apparatus and method of obtaining non-speech data embedded in vocoder packet |
US9083521B2 (en) | 2008-06-05 | 2015-07-14 | Qualcomm Incorporated | System and method of an in-band modem for data communications over digital wireless communication networks |
US8964788B2 (en) * | 2008-06-05 | 2015-02-24 | Qualcomm Incorporated | System and method of an in-band modem for data communications over digital wireless communication networks |
US8594138B2 (en) | 2008-09-15 | 2013-11-26 | Airbiquity Inc. | Methods for in-band signaling through enhanced variable-rate codecs |
US7983310B2 (en) | 2008-09-15 | 2011-07-19 | Airbiquity Inc. | Methods for in-band signaling through enhanced variable-rate codecs |
ES2603987T3 (en) * | 2009-03-03 | 2017-03-02 | Airbiquity Inc. | System control on board a vehicle (IVS) for emergency data communications |
US8036600B2 (en) * | 2009-04-27 | 2011-10-11 | Airbiquity, Inc. | Using a bluetooth capable mobile phone to access a remote network |
US8743864B2 (en) * | 2009-06-16 | 2014-06-03 | Qualcomm Incorporated | System and method for supporting higher-layer protocol messaging in an in-band modem |
US8855100B2 (en) * | 2009-06-16 | 2014-10-07 | Qualcomm Incorporated | System and method for supporting higher-layer protocol messaging in an in-band modem |
US8418039B2 (en) | 2009-08-03 | 2013-04-09 | Airbiquity Inc. | Efficient error correction scheme for data transmission in a wireless in-band signaling system |
US8249865B2 (en) | 2009-11-23 | 2012-08-21 | Airbiquity Inc. | Adaptive data transmission for a digital in-band modem operating over a voice channel |
US8848825B2 (en) | 2011-09-22 | 2014-09-30 | Airbiquity Inc. | Echo cancellation in wireless inband signaling modem |
US10756860B2 (en) | 2018-11-05 | 2020-08-25 | XCOM Labs, Inc. | Distributed multiple-input multiple-output downlink configuration |
US10812216B2 (en) | 2018-11-05 | 2020-10-20 | XCOM Labs, Inc. | Cooperative multiple-input multiple-output downlink scheduling |
US10432272B1 (en) | 2018-11-05 | 2019-10-01 | XCOM Labs, Inc. | Variable multiple-input multiple-output downlink user equipment |
US10659112B1 (en) | 2018-11-05 | 2020-05-19 | XCOM Labs, Inc. | User equipment assisted multiple-input multiple-output downlink configuration |
US11063645B2 (en) | 2018-12-18 | 2021-07-13 | XCOM Labs, Inc. | Methods of wirelessly communicating with a group of devices |
US10756795B2 (en) | 2018-12-18 | 2020-08-25 | XCOM Labs, Inc. | User equipment with cellular link and peer-to-peer link |
US11330649B2 (en) | 2019-01-25 | 2022-05-10 | XCOM Labs, Inc. | Methods and systems of multi-link peer-to-peer communications |
US10756767B1 (en) | 2019-02-05 | 2020-08-25 | XCOM Labs, Inc. | User equipment for wirelessly communicating cellular signal with another user equipment |
Family Cites Families (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4926448A (en) * | 1986-05-06 | 1990-05-15 | Hayes Microcomputer Products, Inc. | Method and apparatus for implementing an escape sequence |
US5005478A (en) * | 1987-12-16 | 1991-04-09 | Precision Engineered Systems Inc. | Blanket wash system with sub-ambient pressure circulation |
US5012489A (en) * | 1988-11-07 | 1991-04-30 | Hayes Microcomputer Products, Inc. | Method for sending a plurality of data channels over a single communications line |
IE62649B1 (en) * | 1990-07-06 | 1995-02-22 | Clancy Martin | A natural and renewable organic compost/fertilizer |
GB2246268B (en) * | 1990-07-19 | 1994-05-18 | Motorola Inc | Facsimile-to-cellular telephone system interface |
TW327488U (en) * | 1991-05-29 | 1998-02-21 | Video Tech Eng | Digital cordless telephone apparatus |
FR2682549B1 (en) * | 1991-10-11 | 1994-01-14 | Apple Computer Inc | METHOD FOR DETECTING AN EXHAUST SEQUENCE FOR THE PASSAGE OF A MODEM FROM A DATA TRANSMISSION MODE TO A CONTROL MODE, AND MODEM PROVIDED FOR IMPLEMENTING THE METHOD. |
US5452289A (en) * | 1993-01-08 | 1995-09-19 | Multi-Tech Systems, Inc. | Computer-based multifunction personal communications system |
USH1413H (en) * | 1993-01-08 | 1995-02-07 | Gunn; Timothy D. | Escape methods for modem communications |
-
1993
- 1993-11-15 US US08/152,158 patent/US5479475A/en not_active Expired - Lifetime
-
1994
- 1994-11-14 RU RU95117903/09A patent/RU2225683C2/en active
- 1994-11-14 CA CA002153148A patent/CA2153148A1/en not_active Abandoned
- 1994-11-14 AU AU10558/95A patent/AU683706B2/en not_active Ceased
- 1994-11-14 DE DE69434451T patent/DE69434451T2/en not_active Expired - Lifetime
- 1994-11-14 JP JP51453895A patent/JP3351533B2/en not_active Expired - Lifetime
- 1994-11-14 KR KR1019950702894A patent/KR100362456B1/en not_active IP Right Cessation
- 1994-11-14 AT AT95901241T patent/ATE301908T1/en not_active IP Right Cessation
- 1994-11-14 WO PCT/US1994/013091 patent/WO1995014356A2/en active IP Right Grant
- 1994-11-14 CN CN94190922A patent/CN1130086C/en not_active Expired - Lifetime
- 1994-11-14 EP EP95901241A patent/EP0679323B1/en not_active Expired - Lifetime
- 1994-11-14 BR BR9405750A patent/BR9405750A/en not_active IP Right Cessation
-
1995
- 1995-07-12 FI FI953418A patent/FI114073B/en not_active IP Right Cessation
-
1996
- 1996-09-20 US US08/717,147 patent/US5761204A/en not_active Expired - Lifetime
-
1998
- 1998-12-28 HK HK98116171A patent/HK1015217A1/en not_active IP Right Cessation
-
2003
- 2003-06-03 FI FI20030828A patent/FI114774B/en not_active IP Right Cessation
-
2004
- 2004-07-14 FI FI20040983A patent/FI116926B/en not_active IP Right Cessation
Also Published As
Publication number | Publication date |
---|---|
FI116926B (en) | 2006-03-31 |
US5761204A (en) | 1998-06-02 |
US5479475A (en) | 1995-12-26 |
EP0679323B1 (en) | 2005-08-10 |
JPH08505995A (en) | 1996-06-25 |
DE69434451T2 (en) | 2006-06-14 |
CN1130086C (en) | 2003-12-03 |
FI953418A (en) | 1995-07-12 |
BR9405750A (en) | 1995-12-05 |
FI114774B (en) | 2004-12-15 |
KR960700614A (en) | 1996-01-20 |
FI953418A0 (en) | 1995-07-12 |
ATE301908T1 (en) | 2005-08-15 |
WO1995014356A3 (en) | 1995-08-10 |
AU1055895A (en) | 1995-06-06 |
HK1015217A1 (en) | 1999-10-08 |
AU683706B2 (en) | 1997-11-20 |
CN1116481A (en) | 1996-02-07 |
EP0679323A1 (en) | 1995-11-02 |
JP3351533B2 (en) | 2002-11-25 |
DE69434451D1 (en) | 2005-09-15 |
RU2225683C2 (en) | 2004-03-10 |
FI114073B (en) | 2004-07-30 |
FI20030828A (en) | 2003-06-03 |
FI20040983A (en) | 2004-07-14 |
WO1995014356A2 (en) | 1995-05-26 |
KR100362456B1 (en) | 2003-02-11 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US5761204A (en) | Method and apparatus of providing time sensitive messages over a variable delay channel | |
CA2158659C (en) | Method and apparatus of providing audio feedback over a digital channel | |
US6611804B1 (en) | Universal TTY/TDD devices for robust text and data transmission via PSTN and cellular phone networks | |
CA2176590C (en) | Method of invoking and cancelling voice or data service from a mobile unit | |
US5726764A (en) | Apparatus and method for providing data and facsimile services in a RF communication system | |
US6400724B1 (en) | Method and apparatus for efficient data transmission in a voice-over-data communication system | |
EP0529104B1 (en) | Telecommunication system | |
KR100417169B1 (en) | Circuitry for transmitting voice and data signals over wireless communication channels | |
US6754265B1 (en) | VOCODER capable modulator/demodulator | |
IL111606A (en) | Method for providing a voice request in a wireless environment | |
US6914965B1 (en) | Method and apparatus of providing a single state mobile unit in a modem connection comprising a wireless link | |
HU217142B (en) | Process for transmitting data first of all gsm data | |
KR100246991B1 (en) | Provision of proprietary and enhanced capabilities in group 3 facsimile for mobile satellite communications | |
US6665312B1 (en) | Synchronous data transmission method and arrangement | |
EP0781062A2 (en) | Radiotelephone system | |
WO2000031984A2 (en) | Improved in-call dtmf transport for geostationary mobile satellite communication system | |
JP2002541746A (en) | Method and apparatus for transmitting data over a voice channel | |
WO1998052368A1 (en) | Transmission of data within a digital wireless communication system | |
WO2002039762A2 (en) | Method of and apparatus for detecting tty type calls in cellular systems | |
WO2001006750A1 (en) | Tty/tdd interoperable solution in digital wireless system | |
MXPA01000422A (en) | Method and apparatus for establishing tdd/tty service over vocoded channels |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
FZDE | Discontinued | ||
FZDE | Discontinued |
Effective date: 20021114 |