A dual mode cellular modem.

The data connection method used in the modem to maintain the data connection between the cellular side of the data connection and the public switched telephone side of the data connection

This case is related to data communication, especially mobile data communication.

The cellular system used in North America today is an analog cellular system, sometimes called AMPS (Advance mobile phone service). AMPS has been standardized in a number of Long Distance Communication Industry Alliance (TIA) standards, such as TR-45.1 and this standardization is based on analog frequency modulation (FM). Each cellular radio channel is a cellular carrier, which modulates an audio signal. The frequency of each cellular radio channel is 30 Kilo Her-tz (KHz).

However, due to the rapid growth of cellular voice communication, the existing AMPS system has become very tense, because AMPS restricts each cellular wireless channel to only one voice. As a result, the long-distance communications industry is looking for different ways to make the restricted cellular system radio spectrum (RF) more efficient. Although there is a mid-term analogy plan for narrowband AMPS (NAMPS), the industry generally believes that the long-term solution is digital transmission.

An access technology based on Time Division Multiplexing (TDMA) has been defined by TIA, which is the Interim Standard (IS)-54. Generally speaking, in this TDMA method, each cellular radio channel carries three digital sound channels, where each sound channel is assigned a separate time slot within the 30kHz RF channel to handle different Conversation. The rough data rate of each time segment is 13kbps. The digital bit string representing the audio signal is coded (compressed), inserted, and transmitted over the air, using a digital modulation technique called Quadrature phase-shift-ke-ying (DQPSK) (Quadrature phase-shift-ke-ying). Digital modulation, error correction codes, and time segment insertion reduce the impact of the weakening of the general radio propagation signal, which makes the capacity of the sound channel three times, without the need for additional RF spectrum, also increases the user capacity, and makes The limited RF spectrum can be more effectively allocated to the cellular system.

Other digital methods are code-devision multi-ple access (CDMA) methods, which are defined in the TIA standard IS-95 and use spread spectrum technology. However, regardless of the final method adopted, the next generation of cellular systems, such as those defined in the TIA standard IS-54, will be a dual-mode system that supports existing AMPS mobile phones and new digital cellular access devices. This dual-mode method provides a migration path to the new digital cellular technology for mobile phone users and cellular service providers. As a result, the new mobile phone design can support both AMPS and digital, such as the use of TDMA technology. In addition, the dual-mode mobile phone will receive signals from the cellular network, and during the voice conversation, decide whether to switch between the analog mode and the digital mode. This allows the hive user to move from an AMPS-based hive to a digital-based hive without talking in the middle of the voice.

Although the main market for cellular communications is voice communications, a growing part of the cellular market is data communications for cellular systems. Although there are some methods that can be used to transmit data in analogous cellular systems, the method used today is Data Communication Equipment (DCE), such as a modem, which couples data terminal equipment, such as a laptop personal computer, to the mobile via a field RJ11 connector. Telephone. The modem modulates a data signal from the laptop computer to a typical quadrature amplitude modulation (QAM) signal. The RJ11 connector transmits the modem QAM signal through the mobile phone area signaling interface, which usually contains itself and couples it to the mobile phone. Telephone. The mobile phone modulates the QAM signal of the modem into a cellular carrier and transmits it to the cellular address transceiver. The latter demodulates the cellular carrier, and provides a QAM signal reception type to the cellular network's mobile communications exchange (MSTO) for transmission to the public switched telephone network and remote data endpoints. This establishes an end-to-end data communication link between the cellular data endpoint and the remote data endpoint. The modem of each endpoint usually has a specific procedure for bidirectional cellular connections, such as ETC^TM(Enhanced Throughpul Cellular) provides better operation.

In the migration of digital honeycomb technology, the method of passing data through the honeycomb is different from the above-mentioned analog-based method. In particular, mobile phones are directly coupled to any DTE through a standard DTE/DCE interface, such as the Electronic Industries Alliance (EIA) RS-232. This DTE/DCE interface directly provides data to the mobile phone in digital form. As a result, there is no equivalent interface connector, such as the RJ11 in the analog system, which needs to transmit data in the digital cellular system.

Unfortunately, although the dual-mode operation of the next-generation cellular system allows the mobile phone to switch between the analog mode and the digital mode during a voice call, this will weaken the data link. In particular, dual-mode mobile phones expect the digits to be serialized in digital bits, such as coupling from the DTE to the PS232 port of the mobile phone. For example, when switching from the analog mode to the digital mode, the mobile phone must compress the analog signal. When the analog signal represents data, such as a QAM modulated signal, this sound compression method distorts the analog signal, destroying the data link and degrading the quality. As a result, during the data call, the cellular data connection must be in analog mode, otherwise it is in digital mode.

We have discovered a method and device that allows cellular data users to switch between analog mode and digital mode without substantially reducing the existing data connection. In one example, the cellular modem switches between analog mode and digital mode operation.

In an embodiment of the present invention, the mobile phone includes a modem, hereinafter referred to as a cellular wireless modem, which supports two types of operations, one is the analog mode, and the cellular wireless modem provides analog signals for transmission. , The other is the digital mode, at this time the modem provides a digital bit string for transmission. During operation, that is, during the existence of a data link to the remote end, the cellular network informs the cellular wireless modem to switch to the appropriate mode-analog or digital. In this embodiment, the remote modem is a part of the modem information database in MSTO. The modem-pool mldem automatically detects the switching of the cellular wireless modem and switches to the appropriate mode. This allows mobile data users to move freely between analog mode and digital mode without interrupting the existing data link.

Fig. 1 is a block diagram of a conventional analog mobile data communication system; Fig. 2 is a block diagram of a conventional digital mobile data communication system; Fig. 3 is a block diagram of a mobile data communication system, which includes a cellular radio modem, which Designed by applying the principles of the present invention; Figure 4 is a flow chart for explaining the method for switching modes; Figure 5 is the flow chart of the cellular radio modem of Figure 5; Figure 5 is the flow chart of the cellular radio modem of Figure 3; Figure 6 is an analogy to The flow chart explaining the exchange method of digital mode, which is used in the cellular wireless modem of Fig. 5; Fig. 7 is the flow chart explaining the exchange method of digital to analog mode, which is used for modem-pool data Figure 8 is a flow chart illustrating the exchange method from digital to analog mode, which is used in the cellular radio modem of Figure 5; Figure 9 is a flow chart illustrating the exchange method from analog to digital mode, which is used for modem-information Library (modem-pool) modem.

Detailed description

Figure 1 is a block diagram of a conventional analog mobile data communication system. As shown in the figure, DTE 10 provides data via line 11 to modem 100, and receives data from it. The modem complies with the DTE/DCE interface standard, such as EIA RS-232. Line 11 represents the transmission line that complies with the EIAPS-232 standard. Letters, electronics and wiring. As mentioned above, the modem 100 modulates the signal from the DTE 10 to the Quadrature Amplitude Modulation (QAM) signal, and provides the signal to the RJ 11 adapter 135 via the line 133. Then, the QAM signal of the modem is coupled to the mobile phone 140 via the mobile phone area sending interface, which is represented by the line 136. The cellular transceiver of the mobile phone 140 further modulates the QAM signal of the modem into a cellular carrier, and the cellular carrier is transmitted to the cellular address transceiver 225. The latter demodulates the received honeycomb signal to provide the QAM signal to the MTSO 250 receiving form. The honeycomb communication channel weakens the channel 200 table. The MTSO provides the received QAM signal to the public switched telephone network (PSTN) 340, which is completed by the PSTN device 341, which is used to transmit to the remote data endpoint, which is represented by the PSTN modem 300 and the DTE 30. This establishes end-to-end data communication between the cellular data endpoint, DTE 10 and modem 100. Usually the modem of each endpoint contains special procedures, which are connected in reverse cellular connection (adverse cellular link), such as better operations on ETC.

A comparatively known data mobile data communication system is shown in Figure 2. Here, the mobile phone 150 is directly connected to the DTE 10 via the line 11, which corresponds to the above-mentioned EIA RS-232 interface. As a result, the data signal from the DTE 10 is already in digital form and can be used for the data mobile phone 150. The mobile phone 150 can use data communication, for example, is equipped with a radio link protocol (RLP). The Radio Link Procedure (RLP) is the industrial name of the procedure, which provides data in a data honeycomb. In addition, as shown in the above TIA standard, the data on the digital honeycomb needs a modem information database in the MTSO, which can be interactively connected with the PSTN. So MTSO 270 includes "Modem Information Library" 280. The modem information database provides two terminal points, one is the honeycomb part for data connection, and the other is the PSTN part for data connection.

As mentioned above, the next-generation cellular system requires a "dual mode" mobile phone, which can be exchanged between the voice mode and the analog mode during voice transmission. Unfortunately, during a data call, this exchange weakens the data link. Therefore, in the present invention, I have discovered a method and device that allows cellular data users to move between analog mode and digital mode without substantially interfering with existing data connections. Especially when a cellular modem is dynamically switched between the analog mode and the digital mode of operation.

Fig. 3 is an embodiment of the mobile data communication system of the present invention. As shown in FIG. 3, the mobile phone includes a modem, hereinafter referred to as a cellular wireless modem 400. For voice conversation, the latter is consistent with the aforementioned IS-54 standard, that is, the cellular wireless modem 400 is a dual-mode circuit. The DTE 10 is coupled to the cellular wireless modem 400 via a line 11, which is consistent with the above-mentioned EIA RS-232 interface. In order to transmit from the DTE 10, the cellular wireless modem 400 either transmits an analog signal, such as a QAM signal, or an analog bit string, to be transmitted to the cellular network 50. The latter includes an antenna 251, a cellular address transceiver 275, and an MTSO 270, which includes a modem signal library 280. The modem information database contains a cellular specific protocol, ETC, which can be used for cellular connections, that is, the connection between cellular wireless modem 400 and modem 285; only standard protocols can be used for modem 290 and PSTN modem 300. The PSTN part of the data link, such as Telephone and Telegroph Consulta-tive Committee (CCITT) v.32 bis. Therefore, only the mobile modem needs cellular specific modulation, and the remote PSTN modem can be a standard modulation. Therefore, mobile data users can call any PSTN modem and operate satisfactorily. For the purpose of the following description, it is assumed that the cellular wireless modem 400 and the modem signal library modem 285 are similar, that is, the two embody the concept of the present invention (described below). It should be noted that in addition to the concept of the present invention, a modem database modem, such as a known person, receives a data bit string on line 276. The data bit string can be a data analog signal (such as PCM or ADPCM), or data.

Fig. 4 is used for the explanation method used in this article to provide dual-mode data function in the mobile data communication system of Fig. 3, which is used when the cellular data connection exists. It is assumed that the data link is established at the beginning, and the cellular address transceiver 275 recognizes cellular calls and data calls. For example, if a voice call is in progress, any voice compression/decompression can be started, but if a data call is in progress, these algorithmic methods operate in the call address transceiver 275. In step 505. The cellular network 50 sends a signal to make the cellular wireless modem 400 enter the digital or analog mode. In the digital mode, this transmission is a part of the digital bit string, that is, if the above-mentioned TDMA method is used, each time slot has its own transmission bit. In the analog mode, this sending is a "blank and burst" operation. (bland and burst). In the blank burst operation, when the sending message is transmitted between the cellular transceiver and the mobile unit, the communication is actually interrupted for a short period of time. Whether the cellular network 50 sends a message to inform the cellular wireless modem 400 to switch to a special mode is determined by some factors. For example, the honeycomb where the honeycomb wireless modem 400 is located has a limited number of analog and digital honeycomb wireless channels. If only an analog mobile phone requests a channel, and the cellular wireless modem 400 is initially on the analog cellular infinite channel, the cellular network 50 can switch the cellular wireless modem 400 to the digital cellular channel and release the analog channel Come out, let it be used only by analog channels. Or the cellular wireless modem 400 can only move to a new cellular, which requires the cellular wireless modem 400 to switch between these two types. After receiving the notification of the switching mode, in step 510, the cellular wireless modem 400 switches the mode. As a result, in step 515, the modem database modem automatically switches the mode through the detection mode switch in the cellular wireless modem 400, as described below.

FIG. 5 shows a block diagram of a cellular wireless modem 400. In addition to the concept of the present invention, the cellular wireless modem 400 is well-known and will not be described in detail here. The cellular wireless modem 400 includes a control processor 405, a data signal processor (DSP) 410, a digital-to-analog and analog-to-digital converter (D/A, A/D converter) 420, and a radio 160. The latter is just the cellular transceiver that controls the processor 405 (described below). The voice part of the cellular wireless modem 400 is not displayed. The control processor 405 receives and provides data from the DTE 10 via the line 11. The DTE 10 complies with the EIA RS-232 specification. The control processor 405 controls the format of the signal received from the DTE 10, which is one of two methods, depending on the mode of the mobile data connection. In the analog mode, the analog signal is transmitted on the line 421, and the control processor 405 assembly procedure, such as CCITT V.42 bis; but in the digital mode, the digital bit string is transmitted on the line 424, and the control processor 405 is equipped with the above RLP procedures. The DSP processor 410 provides actual modulation in the analog mode, that is, an analog modem, while in the digital mode, other parts of the RLP procedure, such as forward error correction (FEC), are assembled. When receiving for transmission to DTE When the data is 10, a complementary function is executed.

As shown in Figure 5, the radio 16 is coupled to the control processor 405, the DSP processor 410, and the D/AA/D 420 via the line 401. The line 401 represents multiple data and control channels. For simplicity, it is divided into three Sending group. Transmitting and receiving analog signals, for example, the above-mentioned QAM signal is transmitted by the line 421, which is hereinafter referred to as the analog bus 421. The transmission and reception of digital signals, that is, a string of digital bits, is represented by the signal transmitted by the line 424, which is referred to as a signal bus hereinafter. As shown in FIG. 5, these digital buses contain at least three signals TXD (transmit data), RXD (receive data), and a CLK (clock) signal. The most-control-transmitting signal is a list of the signals transmitted by the line 423, which will be referred to as the control bus 423 hereinafter. The control processor 405 instructs the radio 160 via the control bus 423 to select an analog bus or a digital bus for the transmission and reception of information in the cellular network 50.

At this point, please refer to FIG. 6, which shows a description of the method used in the cellular wireless modem 400 to provide dual-mode functions. It is assumed that in step 605, an initial action data link is established in an analog mode. This allows the mobile data user of the DTE 10 to receive and transmit data from the remote data endpoint DTE 30, while it is located in an analog-based honeycomb, that is, there is no need for analog-based mobile communication. This data link includes modem-pool modems 285 and 290. When the mobile data user moves from an analog-based honeycomb to a digital-based honeycomb, the cellular wireless modem 400 is notified that it must switch to a digital form to make it consistent with the aforementioned IS-54 standard. In step 610, it receives a command to switch to the digital mode, the control processor 405 switches to the digital mode, and in step 615, it immediately starts to transmit the subsequent frame. When switching from analog mode to digital mode, layer 2 procedures deal with any missing or damaged frames.

Figure 9 is an illustration of the method used in the modem database modem 285, which can be switched from the analog mode to the digital mode. As shown above, the cellular wireless modem 400 starts to switch the mode after receiving the cellular network notification to switch the mode. As a result, the modem information database modem 285 needs some method of decision when the cellular wireless modem 400 switches modes. Therefore, consistent with the present invention, the modem signal modem 285 simultaneously monitors the data signals of the digital mode and the analog mode on the line 276. Particularly, the modem 285 processes the data represented by the data signal in step 810. However, the modem database modem 285 can simultaneously monitor the bit string represented by the data signal for the valid digital modem. If there is no valid digital data, the modem database modem 285 to step 825, the following steps The modem information database modem 285 is allowed to confirm via the cellular wireless modem that one of the switches can be switched from analog to digital mode. The modem 285 calculates the received data signal, and determines whether it is a bad analog signal from an analog point of view. In other words, if it is a bad signal, there will be an uncorrectable error when the signal is returned from the analog mode data signal, and if it is a good signal, the error can be corrected or there is no error. If the data machine in the data machine database calculates the data signal, which is represented by a good analog signal, the data machine in the data machine information library will continue to process in the analog mode. However, if the data base modem determines that the quality of the analog signal has deteriorated, then in step 380 the data base modem switches to the digital mode, and in step 835, the data signal is processed in the form of a digital data frame.

When in digital mode, mobile data users can move from a digital-based honeycomb to an analog-based honeycomb. Figure 7 shows the method from the analog mode to the digital mode. Similarly, at the beginning of step 705, it is assumed that the action data connection is in a digital form. When the mobile data user moves from a digital basic honeycomb to an analog basic honeycomb, the honeycomb wireless modem 400 is told to switch to the analog mode according to the aforementioned standard IS-54. In step 710, when a command to switch to the analog mode is received, the control processor 405 sends a command to the DSP processor 410 to switch to the analog mode and in step 715, a standard training sequence is sent to the modem signal library Modem 285. For example, CCITT V.32 bis signal AA or AC can be used. If the cellular wireless modem 400 is an answering modem, it sends a signal AA, and if the cellular wireless modem 400 is an initial modem, it sends a signal AC. In step 720, the cellular wireless modem 400 continues to send the training sequence until a confirmation training sequence is received from the modem 285 of the modem information database. In other words, the cellular wireless modem 400 performs a bandshaking sequence (bandshaking sequence) before sending any data.

What is shown in FIG. 7 is a corresponding method for the modem to switch from the digital to the analog mode. The modem 285 processes the data signal in the digital mode in step 750. As described above, in step 755, the modem 285 monitors the data information in the digital mode and the analog mode at the same time. Need to know the data information database data machine 285 online 276 to receive-64KPCM (pulse code modula-ted) signal. The PCM signal can be represented by a digital signal or a PCM representation of analog data. Basically, the analog-digital part of the dual-mode modem monitors the PCM signal stream for training sequences. If the standard training sequence is not detected, the data base modem continues to process the digital signal in the digital mode in step 750. However, when the standard training sequence is detected, the modem database modem 285 to the crew 765. The latter step allows the data information database modem 285 to confirm that there is a switch from the cellular wireless modem 400 from the digital mode to the analog mode. From the data point of view, the modem 285 calculates the received data to determine whether it is a bad signal. If it is a good signal, that is, there are no errors or correct errors, then the modem continues to use the digital The mode processes the signal. On the contrary, if the signal quality has deteriorated, the modem 285 switches to the analog signal and responds to a training sequence, AC or AA, and this action is performed in step 775. The training sequence from the modem information database modem 285 also depends on whether the modem 285 is a start or answer modem. When the modem of the modem information database is a positive training, the cellular wireless modem 400 continues this training. This can be seen from FIG. 3, because the honeycomb part where the data is continuous ends between the modem information database 285 and the honeycomb wireless modem 400, the standard training sequence is not used. For example, the revised V.32 The bis training sequence can be defined as a non-training echo canceller, that is, the CCITT V.33 training sequence is used. The resulting retraining is faster than the standard V.32 bis training sequence. Layer 2 procedures (error control routines) deal with any missing or corrupted data between the analog mode and the digital mode.

As shown above, the present invention allows the cellular modem to switch between analog mode and digital mode without degrading data transmission. This allows the data signal of the modem to be processed depending on the operating mode. In addition, because the cellular modem control processor can perform compression and error control in both analog and digital modes at the same time, it can easily continue compression and error control when switching between the analog and digital modes of operation.

The above only illustrates the principle of the present invention, so those skilled in the art of the present invention will be able to design a variety of different devices that realize the principle of the present invention and are within the viewpoint of the present invention.

For example, in the above embodiment of the cellular wireless modem that automatically switches between analog and digital modes, the switching operation can be performed in other ways. One example is that the cellular wireless modem first sends a command to the modem in the modem database to switch modes. This command can be a release sequence, similar to the one defined in the standard TR30.4, each time the data mode is switched, or the remote loop sequence defined in CCITT V.54 can be used as a unique character code, or used in CCITT The analog control carrier LSD blocking sequence defined in V.13. Moreover, the cellular wireless modem must be confirmed from the modem in the modem database before switching modes. Even the notification to the remote modem can be provided by the cellular network.

In addition, although the figure shows the cellular modem and the mobile phone as a unit, in fact, the two can also be separated. This will enable the mobile phone to connect to the cellular modem via the peer-to-peer line 401. However, the mobile phone can also notify the cellular modem via the control bus, which is an action that needs to be performed when the mobile phone receives a command to switch the mode from the cellular network.