JP2005510116A - System and method for initiating communication between transceivers - Google Patents

Abstract

  Disclosed are methods and systems for initiating and synchronizing communications between transceivers. The transceiver can communicate with any of a number of communication schemes. The method of operation of the first communication transceiver includes a step (400) of starting operation in a setting mode so that a preference order of a plurality of communication methods is established, and switching to a re-training mode if necessary. Retraining (500) the selected communication scheme as dictated by the communication scheme preference order and communicating with the second communication transceiver in the selected communication scheme.

Description

RELATED APPLICATION This application claims the benefit of US Provisional Application No. 60 / 344,486, entitled “Installation Mode for DSL Transceivers”, filed on Nov. 9, 2001, It is incorporated herein by reference in its entirety.

TECHNICAL FIELD The present invention relates generally to data communication systems, and more particularly to systems and methods for initiating communication between transceivers.

Background Art There is an ever-increasing demand for higher speed and larger volume transmission of voice and data. One solution that meets these requirements is Digital Subscriber Line (DSL) technology. DSL technology has been introduced in the field of broadband networking to overcome the problems faced by traditional voice band technology, among other reasons. Such a problem includes, but is not limited to, bandwidth limitations. Includes rate adaptive DSL (RADSL), symmetric DSL (SDSL), multirate SDSL (M / SDSL), high bit rate DSL (HDSL), very high bit rate DSL (VDSL), and asymmetric DSL (ADSL), There are many DSL technologies without being limited thereto.

  ADSL technology takes advantage of the infrastructure already deployed in the public switched telephone network (PSTN), which includes a copper loop built with copper wire between the subscriber premises and the central office. ADSL technology advantageously does not require the replacement of network equipment such as routers, switches, firewalls, and web servers that are commonly used in today's broadband access paradigms.

  DSL modems provide communication capabilities for transmitting and receiving information, for example using ADSL technology. In general, discrete multitone (DMT) line coding is utilized by DSL modems for transmission of DMT symbols from a source to a destination. Several DMT communication schemes, sometimes referred to as line coding techniques, are known in the art, each having advantages and disadvantages based on several variables such as bit rate, error rate, and reach. The following are some communication schemes well known in the art.

  The first set of DMT communication systems is a G.264 standard created by the International Telecommunication Union (ITU-T). 992 Annex A, ADSL Recommendation. In general, Appendix A covers a portion of the North American, Asian, and European markets. Two common types of communication schemes in Annex A are frequency division multiplexing (FDM) and echo cancellation (EC). In FDM mode, the downstream and upstream signals use separate frequency bands. The available upstream band is defined as 0 to 138 kHz, and the downstream band is defined as 138 kHz to 1.104 MHz. In EC mode, the downstream signal can coexist in the same band as the upstream signal and thus has a larger downstream band. Therefore, in the EC mode, the downstream signal can use 0 Hz to 1.104 MHz, while the upstream band is the same as that in the FDM mode. The advantage of EC technology over FDM technology is clearly an increase in downstream bandwidth. The disadvantage is that crosstalk can occur due to overlap in the 0 to 138 kHz range, and the necessary resources are required to counter this.

  In Japan, there are basically two major DSL technologies. Another set of DMT communication systems is G. It is defined by Annex C of the 922 recommendation and is based on the special network characteristics of Japan. These factors include the existence of a very large ISDN user base. ISDN is a kind of “Ping-Pong” type time division transmission with a poor low-pass filter that causes high transmission signal levels and significant levels of crosstalk interference, time compression multiplexed (TCM) ISDN Point to. In addition to the presence of TCM-ISDN, paper insulated cables are used, which causes high attenuation at high frequencies. Together, these factors create a situation where a high level of interference occurs when using the ADSL of Annex A, making this type of device unusable with many copper loops. Annex C employs advanced techniques of synchronization and noise margin calculation (to mitigate the harmful effects of interference and attenuation) to meet the high level quality and efficiency requirements of Japanese ADSL. ing.

  Within Annex C, there are two types of transmissions, Far End Crosstalk Bitmap (FBM) and Dual Bitmap (DBM), and it is generally understood that FBM is simpler of the two. Yes. The FBM transmits only during the far-end crosstalk (FEXT) cycle and matches the transmission direction of ISDN. Since the FBM limit uses only 37% of the symbols, the bit rate can be limited. This means a downstream data rate of just over 3 Mbps in the case of full rate ADSL.

  The second type of transmission, or DBM, is more difficult to implement because some transmission occurs in the next cycle. However, a line with little ISDN noise can achieve the same rate as Appendix A, so it is worth overcoming the difficulties.

  G. Annex H of 992 is another communication scheme that is symmetric and uses all available frequency bins, but transmits only during the FEXT cycle. The same as FBM. This technology requires a digital signal processing (DSP) core that is powerful enough to handle up to 255 bins upstream and downstream. The advantages of Annex H line coding techniques are obvious. That is, it provides DSL for the Japanese market and can achieve higher speeds than Annex C FBM because more downstream bins are used.

  As mentioned above, there are currently several communication schemes, each with its own advantages and disadvantages. However, as is well known, the loop states are very diverse. A communication scheme that works best for one loop may be better for a different loop. Unfortunately, loop characteristics (of the same loop) can change over time, so a communication system or line coding technique that works best on one day is better on another day. It may be.

  There is therefore a need to find solutions to these problems.

DISCLOSURE OF THE INVENTION The present invention is directed to a method, apparatus, and program for initiating and synchronizing communications between transceivers so that the best communication scheme is realized based on the state of the loop. The transceiver can communicate in any of a plurality of communication schemes. An exemplary method is to detect a remote transceiver that is communicatively connected to a central office transceiver, to determine a suitable communication scheme to be utilized by the central transceiver and the remote transceiver, and to communicate with the central office transceiver in a suitable communication scheme. Training the transceiver and the remote transceiver, and initiating communication between the central office transceiver and the remote transceiver.

  Another embodiment can be interpreted as a method for operating a first communication transceiver capable of communicating in a plurality of communication schemes. The method starts the operation in the setting mode so that the order of preference of the multiple communication methods is established, switches to the retraining mode if necessary, and selects as ordered by the preference order of the multiple communication methods. Retraining with the selected communication scheme and communicating with the second communication transceiver with the selected communication scheme.

  Another embodiment can be interpreted as a communication system. The system includes a first transceiver configured to communicate in any of a plurality of communication schemes, and a second transceiver communicatively coupled to the first transceiver, the second transceiver including a plurality of communications. It is configured to communicate with at least one of the schemes. The first and second transceivers are further configured to negotiate a suitable communication scheme. The first and second transceivers are also configured to train to communicate in a suitable communication scheme if necessary and to initiate and synchronize communication in a suitable communication scheme.

  Another embodiment is in a situation where the first transceiver is configured to communicate in any of a plurality of communication schemes and the second transceiver is configured to communicate in at least one of the plurality of communication schemes. It can be interpreted as a first transceiver including means for communicatively connecting with a second transceiver and means for negotiating a suitable communication scheme. The first transceiver also has means for training the first and second transceivers to communicate in a suitable communication manner and means for initiating and synchronizing communications in the preferred communication manner. Including.

  Yet another embodiment is provided in a situation where the central office transceiver is configured to communicate in any of a plurality of communication schemes and the remote transceiver is configured to communicate in at least one of the plurality of communication schemes. It can be interpreted as a program for initiating and synchronizing communications between the transceiver and the remote transceiver, and the program is stored on a computer readable medium. The program includes logic configured to detect a remote transceiver communicatively connected to the central office transceiver, logic configured to determine a preferred communication scheme to be utilized by the central office transceiver and the remote transceiver, Logic configured to train the station transceiver and the remote transceiver to communicate in a suitable communication scheme and configured to initiate communication using the preferred communication scheme between the central office transceiver and the remote transceiver Included logic.

Detailed Description of the Invention The drawings will now be described. Like reference numerals refer to corresponding parts throughout the drawings. FIG. 1 is a block diagram illustrating a communication system 12 that can provide an embodiment of the present invention. Specifically, FIG. 1 shows communication between the central office 20 and the customer premises 22 via the local loop 24. Customer premises 22 can be detached houses, small businesses, or other entities, but typically have POTS equipment such as telephones 26, PSTN modems 27, facsimile machines (not shown), etc. Characterized as Customer premises 22 can also include an xDSL communication device such as an xDSL modem 28 with an ADSL interface card 100A for handling ADSL services. Without being limited thereto, a POTS filter 30 can be interposed between the POTS device 26 and the local loop 24 when an xDSL service such as ADSL is provided. Needless to say, Lite, ADSL. When Lite or other similar communication method is used, it is not necessary to provide the POTS filter 30. As is well known, the POTS filter 30 includes a low pass filter to filter out high frequency transmissions from the xDSL communication device 28 and protect the POTS equipment.

  It should be noted that although the present disclosure is made in the context of ADSL technology, those skilled in the art will appreciate that other DSL technologies that require different modulation and communication schemes can be used.

  The central office 20 is provided with an additional circuit mechanism. In general, an xDSL modem 40 including line interface circuitry is provided for electrical connection to the local loop 24. Indeed, a plurality of modems 40, 42 can be provided to handle a plurality of local loops 24. Similarly, the central office 20 is typically provided with an additional circuit card to handle different types of services. For example, a digital integrated services network (ISDN) interface card (not shown) and other circuit cards can be provided to support similar and other communication services. In particular, in the synchronization system of the present invention, the ADSL interface card 100B can be provided in the central office 20 in order to handle the ADSL service. Note that alternatively, the ADSL interface card 100A (or 100B) can be located only at the central office 20 or only at the customer premises 22.

  A digital switch 50 is also typically provided at the central office 20 and is arranged for communication with each of the various modems 40 and 42. A plurality of trunk cards 52, 54, 56 are generally provided on the exit side of the central office 20 (ie, on the opposite side of various local loops). These cards typically support multiple multiplexed transmissions and have outgoing lines that are typically addressed to other central stations or long-range central stations.

  FIG. 2 is a block diagram further illustrating a connection between the xDSL modem 40 (hereinafter referred to as CO modem 40) of the central office 20 and the xDSL modem 28 (hereinafter referred to as CP modem 28) of the customer premises 22 (FIG. 1). Data transmission can be directed in both directions simultaneously from the customer premises 22 to the central office 20, from the central office 20 to the customer premises (CP) 22, or via a local loop 24. In general, each modem 28 and 40 may include a processor 120, a memory 110, and an ADSL interface card 100, all coupled via a local interface 130. The CO modem 40 can include a network interface 140 that facilitates communication with the digital switch 50 (see FIG. 1) of the CO 20. Similarly, the CP modem 28 may include an I / O interface 150 that facilitates connection to a computing device such as a PC. A home local area network (LAN) (not shown) can be connected to the CP modem 28, in which case the I / O interface 150 is between the appropriate hardware (ie, server or router and CP modem 28) over the LAN. Communication can be interfaced. In the discussion below, a single reference number is designated when referring to similar elements of two modems. When referring to one modem element, specify a reference number with letters. For example, reference numeral 130 is used to refer to both local interfaces 130A and 130B. When referring to only one local interface, either 130A or 130B is used. Those with “A” represent components of the CP modem 28, and those with “B” represent components of the CO modem 40.

  The local interface 130 can be, for example, but not limited to, one or more buses or other wired or wireless connections, as is well known in the art. The local interface 130 can have additional elements such as controllers, buffers (caches), drivers, repeaters, and receivers to allow communication, but they are omitted for the sake of brevity. Has been. Further, the local interface 130 can include address, control, and / or data connections to allow proper communication between the components described above.

  The processor 120 is preferably a hardware device for executing software or firmware stored in the memory 110 in particular. The processor 120 can be any custom or commercially available processor, central processing unit (CPU), auxiliary processor among several processors associated with the modem 28 or 40, semiconductor based (in the form of a microchip or chipset). It can be a microprocessor, a macro processor, or generally a device for executing software instructions.

  The memory 110 is one or a combination of a volatile memory element (for example, random access memory (RAM such as DRAM, SRAM, SDRAM, etc.)) and a non-volatile memory element (for example, hard disk drive, tape, NVRAM, CDROM, etc.). Can be included. Further, memory 110 may incorporate electronic, magnetic, optical, and / or other types of storage media. The memory 110 may have a distributed architecture in which various components are remotely located with respect to each other and can be accessed by the processor 120.

  The memory includes appropriate resources or drivers 111 for various communication schemes. For example, drivers necessary to prepare for frequency division multiplexing (FDM) discrete multitone (DMT) modulation can be stored in memory 110. The CP modem 28 can include a driver 111A similar to that of the CO modem 40 for the corresponding communication scheme. In other cases, the CP modem 28 can communicate with another set of communication schemes similar to the CO modem 40, so the memory 110 A of the CP modem 28 includes a different set of drivers 111 A than that of the CO modem 40. It is.

  Also stored in the memory 110 of both modems 28 and 40 is a program 115 for determining a suitable communication scheme and then establishing and synchronizing communication between the modems 28 and 40. Program 115 can be a segmented modular program, so segments 116 through 119 of program 115 can be distributed and / or duplicated between the two modems 28 and 40. For purposes of illustration, several segments 116-119 are shown in FIG. The training segment 116 of the program 115 can provide resources for training one or both of the CO modem 40 and the CP modem 28 for communication in a particular communication scheme, thereby enabling for this communication scheme. Appropriate resources can be included in the driver 111.

  Other segments of program 115 include monitor segment 117, synchronization segment 118, and test segment 119. Each provides resources for various functional aspects of program 115. As described above, the segments can be included in the CP modem program 115B and / or program 115A like the others. This provides flexibility in the configuration of the communication link between the two modems 28 and 40. In general, in the preferred embodiment, the CP modem 28 acts as a slave of the CO modem 40 and therefore the CO modem 40 tends to provide the majority of the control of the link.

  In general, program 115 provides for the execution of various algorithms and methods disclosed herein. The various functions and methods of the present invention are further discussed in the following figures. Various functional aspects of the program 115 will become apparent from these figures.

  In alternative embodiments, resources for communicating in various communication schemes and programs and / or algorithms for performing the methods disclosed herein may be located in memory remote from modem 28 or 40. A remote server or PC coupled to the CP modem 28 or a remote location at the CO 20 is a non-limiting example of an alternative location. Modems that have available resources to communicate in various communication schemes are sometimes referred to in the industry as multimode modems, and similarly, another term often used in the industry for modems in general is transceiver. .

  The ADSL interface card 100 is generally a hardware component that serves to properly transmit and receive electronic signals carrying line encoded information in a particular communication scheme. In brief, the processor 120 executes related software and / or firmware instructions stored in the memory 110 of the ADSL interface card 100. Signaling instructions, encoding instructions, modulation instructions, and instructions involved in the method of the present invention are non-limiting examples of instructions executed by the ADSL interface card 100. ADSL interface card 100 typically includes a digital signal processor (DSP), which receives information from either network interface 140 or I / O interface 150 and sends information to an analog front end (AFE). The AFE interfaces between the local loop 24 and the DSP and functions to convert digital data from the DSP into a continuous time analog signal. The analog signal is sent via a line driver. Incoming signals are generally processed through the interface card 100 in a similar manner. The front end hybrid of loop 24 separates the transmitted and received signals. A DSP and other components may be required to execute the various instructions described above.

  In the upstream direction, digital data is basically received by the CP modem 28 via the I / O interface 150, processed and provided to the ADSL interface card 100A via the local interface 130A. The data is then modulated according to the communication method used, converted to analog form and transmitted along the loop 24. The information is then converted to digital by the ADSL interface card 100B of the CO modem 40. It is then demodulated using the same communication scheme and provided to the network interface 140 for further transmission and / or processing.

  Before the data is transmitted on the local loop 24, several operations are performed. An initial handshake algorithm is utilized by modems 28 and 40 to determine whether a local loop connection has been established. The International Telecommunication Union (ITU) Standardized the handshake procedure for DMT communication in 994 recommendation. Modem training is performed to measure performance and / or error rate in connection with the local loop 24. Appropriate synchronization is also performed between the two modems. These operations may vary depending on various communication schemes or line coding techniques. Note that in this document, the term “line coding technology” is used interchangeably with the term “communication scheme”. The result of the operation depends on the state of the local loop 24, which can change at any time. The operation of system 12, particularly the operation of modems or transceivers 40 and 28 according to embodiments of the present invention, can best be described in the flowchart provided below.

  In the following description, a flowchart is provided. A process step or block in these flowcharts is intended to represent a module, segment, or portion of code that includes one or more executable instructions for performing a particular logical function or process step. I want you to understand. To that end, some or all of these steps or blocks may be performed in software, hardware, firmware, or a combination thereof. While specific example process steps are described, it should be understood that alternative embodiments are possible. Further, the steps can be performed in a different order than shown or described, including substantially the same order, or in reverse order, depending on the functionality involved, as will be appreciated by those skilled in the art.

  The methods and alternative embodiments of the present invention described herein can include an ordered list of executable instructions for performing a logical function, such as a computer-based system, a system including a processor, etc. Any instruction execution system, device, or apparatus, or any other system that can retrieve instructions from and execute instructions from an instruction execution system, apparatus, or device, or any computer-readable device for use in connection with them Can be embedded in media. In the context of this document, a “computer-readable medium” is any means that can contain, store, communicate, propagate, or transfer a program for use by or in connection with an information system, device, or apparatus. can do. Further specific examples (non-exclusive list) of computer readable media include: Electrical connection (electronic) with one or more wires, portable computer diskette (magnetic), random access memory (RAM) (electronic), read only memory (ROM) (electronic), erasable read only memory (EPROM or Flash memory) (electronic), optical fiber (optical), and portable compact disc read only memory (CDROM) (optical). The program can be captured electronically on paper or other media, for example by optical scanning, and then compiled, interpreted, or otherwise processed as appropriate, if necessary, and then stored in computer memory The computer readable medium may even be paper or other suitable medium on which the program is printed.

  FIG. 3 is a flowchart illustrating a method 200 for initiating and synchronizing communications between a central office transceiver and a remote transceiver, performed in accordance with an embodiment of the present invention. The central office transceiver can be the CP modem 40 of FIGS. 1 and 2 and the remote transceiver can be the CP modem 28. Method 200 begins when they detect that the CO and CP transceivers are communicatively connected to each other (step 210). This can start from either end, but more generally it starts from the CP end. This can mean several things. First, a loop is established between the two transceivers. Secondly, if both transceivers are powered on, otherwise they can do so. The detection of a connection between two devices can be done in several possible ways known in the art, and the specific way to do so is outside the scope of this document.

  The method 200 proceeds to determine a preferred communication scheme among several communication schemes (step 220). Non-limiting examples of schemes are the DMT modulation scheme described above, Echo Cancellation (EC) in Appendix A, Frequency Division Multiplexing (FDM), Far End Crosstalk Bitmap (FBM) Dual Bitmap (DBM) in Appendix C It can be. Other communication schemes can be used, including those that do not use DMT modulation. A method for determining a suitable communication method will be described in the following flowchart.

  Once the preferred communication scheme is determined, the CO and CP can be trained to communicate in the preferred communication scheme in a predetermined loop (step 230). In some embodiments, both devices need to be trained, while in other embodiments, only one device needs to be trained. In yet another embodiment, neither device needs to be trained, in which case this step can be completely eliminated. In order to train the device, each modem (or transceiver) can transmit a specific signal as defined in a given DSL standard. Using these known signals, each transceiver can synchronize with each other and estimate the signal-to-noise ratio (SNR) of the channel, which in turn determines the final data rate, negotiation rate, performance margin, etc. To do. In general, there are many different ways to train a transceiver. Equipment training is well known in the art and is outside the scope of this document.

  After the transceiver is properly trained, communication between the two devices begins (step 240). Communication is a suitable communication method.

  While communication between the two devices is being performed, communication performance is monitored, including channel characteristics monitoring (step 250). Several parameters of performance can be measured and are described in more detail in this document. Either or both of the devices can be configured to monitor communication performance. After monitoring communications, several things can be done. In this embodiment, the communication method used can be changed (step 260). This may require re-determining the preferred communication scheme from the various communication schemes available for the two devices (subtracting the scheme used now). In short, steps 220 through 250 can be repeated as often as necessary until the communication scheme yields consistent results after the start of communication. After monitoring the communication system, a prompt to change the communication system can be automatically issued. In some embodiments, this can be done by setting a default parameter for the performance variable. Once these parameters are exceeded, step 260 can begin. In other embodiments, this can be done manually by a CP technician or user. The device can do both. That is, in the normal operation, the method can be changed automatically, but the communication method can be changed by overriding the system. In that case, step 220 can be used, or any device can specify a particular scheme. The preferred embodiment has the ability to override the system and change the communication method if a CO transceiver is required. A well-known method in the art for sending commands from one device to another is performed via the Embedded Operations Channel (EOC). EOC is a dedicated channel used in some xDSL technologies apart from the standard data channel and is generally used for maintenance purposes. A command can be transmitted from one device to another device from the CO device to the CP device to instruct which communication method to use. Other methods for communicating these commands can also be used.

  FIG. 4 is a flowchart illustrating a general method 290 of operation of a communication transceiver according to an embodiment of the present invention. In general, this method can be performed by a master transceiver in a master-slave configuration. There is no need to have a master-slave configuration, but it may be useful to set the priority for which communication method to use. In a preferred embodiment, the CO transceiver can be a master device and the CP transceiver can be a slave device. In other embodiments, the reverse can certainly be used. Also, the method of operation 290 disclosed herein is configured for a multimode modem or multimode transceiver, and more particularly for a multimode xDSL modem that utilizes DMT modulation techniques or DMT communication schemes. Please pay attention to. In general, however, this method of operation 290 can be utilized with any transceiver configured to communicate with any communication scheme on any medium. In that sense, single mode transceivers can also utilize this method of operation.

  Method 290 begins in configuration mode (IM) (step 400). In general, the initiation of communication between two devices by a suitable communication scheme can be achieved with IM. Therefore, the determination of a suitable communication method can be achieved by IM as well. IM starts when the transceiver is first powered on on any line. If any device is subsequently started, it can begin operating in a suitable communication manner, thus potentially eliminating timely IM. On subsequent startups, if the preferred communication method is not available, the next preferred communication method can be attempted, and so on until a connection is established or no communication method is currently in effect, The latter means a serious defect in the channel. IM will be further described in FIG.

  Once the IM is complete, the start of communication begins with a suitable communication scheme. Communication between the two devices is labeled as a device operating in data mode (DM) (step 440). That is, data is communicated between the two devices. However, if necessary, the transceiver can switch to a retraining mode (RM) in order to properly start proper training of the two devices before starting operation in the DM (step 500). Even at the time of DM, the transceiver can be returned to the configuration mode. This can be done automatically after monitoring the communication performance. This can also be done manually by overriding the system and returning to IM. The technician may wish to test a particular communication scheme, so this can be achieved by switching to IM. The system can override at any point in operation, including during RM.

  The RM mode can be started if (re) training has to be done for a communication scheme that utilizes one or all of the devices of the communication system. After (re) training, the device can be returned to the DM. RM will be described in more detail with reference to FIG.

  FIG. 5 is a flowchart illustrating a method 400 for setting communications performed during the setting mode of operation method 290 of FIG. Method 400 or IM begins when the master transceiver is first powered up (step 410). In this embodiment, the CO transceiver is the master transceiver, but in other embodiments the reverse may be true.

  When powered up, the CO transceiver starts detecting the CP transceiver at the opposite end of a given line. As mentioned above, many methods for detecting another transceiver are known in the art, and therefore this description excludes the description of a particular method. In general, a CO transceiver attempts to detect a CP transceiver until one is detected or until the algorithm times out.

  Once detected, several communication modes, or several communication schemes can be evaluated (step 300). The CO transceiver may be able to communicate with a different group of communication schemes than the CP. After evaluation, a list of compatible communication methods and a log of each related performance measurement can be generated. An ordered list of communication system preferences can also be generated. This step is discussed in more detail in FIG.

  Next, an attempt is made to initiate communication with the preferred communication scheme from the communication scheme ordering list (step 430). If necessary, the CO transceiver can be switched to RM (see FIG. 4) to initiate an appropriate training sequence for the newly determined preferred communication scheme.

  From there, the DM operation begins (step 440). The performance of communication between the two devices is monitored. Either one or both of the devices can monitor performance. Records can be made to track and store performance over time. If an abnormal or dramatic change occurs in the line status, the CO transceiver can be switched to the setting mode. As described above, the preferred embodiment utilizes an xDSL transceiver configured to utilize DMT line coding. Not only some line coding techniques discussed in the background, but also some other techniques can be utilized. Instead of switching to IM immediately, a restart can be attempted with the communication method used. If this attempt times out, the next communication method in the ordered communication method list can be attempted, or the device can be returned to the IM. If necessary, the retry time of the used communication method until the line is released can be set to several minutes.

  After that, the timely step 300 for evaluating various communication schemes can be omitted. Startup can begin with the first communication scheme available in the ordered list of communication schemes. If an attempt to start with the next communication scheme fails, that is, if the attempt times out, the next communication scheme can be attempted. The length of the timeout can generally vary by a matter of seconds.

  FIG. 6 is a flowchart illustrating a retraining method 500 performed during the retraining mode of the method of operation 290 of FIG. The method 500 can begin at any time. For example, the method 500 can begin as soon as a suitable communication scheme is determined at the IM. Training can then be performed in that manner. In another example, the method 500 may begin when it is determined during DM that performance will be enhanced by retraining of the utilized communication scheme.

  In general, method 500 begins when a transceiver switches to RM. If it is not yet known whether the device needs retraining, the transceiver confirms it (step 510). This can be accomplished in several ways, such as communicating with a reciprocal transceiver via EOC (see FIG. 3). If it is determined that no retraining is required, the transceiver can switch to DM (step 440). If it is determined that the receiver needs to be retrained, an appropriate training sequence is initiated (step 520). As mentioned above, several training sequences are known in the art, and any particular training method or sequence is outside the scope of this document.

  FIG. 7 is a flowchart illustrating a general method 300 for determining a preferred communication scheme according to an embodiment of the present invention. Method 300 is generally not only in the mode of operation 290 configuration mode, but also in method 200 for initiating and synchronizing communications between a central office transceiver and a remote transceiver performed by embodiments of the present invention. This is the method used. In the latter case, the method 300 corresponds to step 220, ie “determining a suitable communication method”. The method 300 determines that a first transceiver (preferably a CO transceiver, but not necessarily) detects a second transceiver (preferably a CP transceiver, but not necessarily). To be started. The first step is to try to communicate with the first communication scheme, which is clearly the scheme with which the first transceiver can communicate. The second transceiver may not be able to communicate with any one, some, or all of the communication schemes within the capabilities of the first transceiver. Regardless, the first communication scheme is attempted. After this attempt, several performance characteristics are measured. One example is connectivity, i.e. whether the second transceiver can communicate in this manner. For the purposes of this document, connectivity shall be taken to mean whether a communication connection can be established with the second transceiver in a predetermined communication scheme. In contrast to this qualitative measurement, several quantitative measurements can be made. These quantitative measurements include, but are not limited to, downstream rate, upstream rate, downstream SNR margin, upstream SNR margin, and the like. Several variables can affect the performance measurement of each communication scheme. For example, in Japan, a paper insulated cable is generally used for the local loop. DMT schemes for Annex A xDSL (eg EC and FDM) may not be the best suited for these conditions because high attenuation occurs at high frequencies, which can lead to high levels of interference. Absent. Annex C techniques such as FBM and DBM use techniques that mitigate the effects caused by attenuation. The disadvantage is that Annex C can only use about one third of the downstream bit rate.

  In the preferred embodiment, a multi-mode xDSL modem that utilizes the DMT communication scheme is utilized. In this case, the test of each communication method is performed by G.I. This can be done according to the standards defined by the 994 recommendation. This allows compatibility with components already compliant with the standards recommended by ITU-T. Ease of design, marketing, and other business decisions makes compliance with this industry standard beneficial. However, it should be noted that in other embodiments, the method of testing and the parameters to be tested will depend on the technology at hand, and thus the preferred embodiment should not be considered as a limiting example.

  After each communication scheme is tried and tested, performance data can be collected (step 320). After monitoring, a performance data log is created and maintained. Steps 310 and 320 can be repeated for all communication schemes attempted.

  Further calculations can be performed on various performance characteristics to generate a preference order (step 330). These calculations will vary not only depending on the customer profile of the serving market but also on the technical and functional aspects of the plant under test. In general, methods, algorithms, equations, etc. for determining the order of preference of communication schemes may vary and can be created and manipulated as required by the service provider. It should also be noted that the order of preference and subsequent preferred communication schemes can be overridden by the service provider. After the order of preference is created, the best mode of operation, or the preferred communication method, can be selected (step 340).

  Referring now to FIG. 8, a flowchart of a general method 600 for synchronizing and training a remote transceiver to communicate in a suitable communication scheme in accordance with an embodiment of the present invention is shown. Method 600 begins when a remote transceiver or CP transceiver is powered on (step 610). The CO transceiver detects both during setup mode and data mode.

  In the setting mode, various communication schemes are tried and performance is tested. The particular order in which the various communication schemes are tested can vary, and method 600 describes a preferred method. As soon as power is turned on, a first set of communication schemes can be attempted (step 620). In this embodiment, the method of Appendix A is tested. For example, echo cancellation DMT can be tested for a period of time. Once connectivity is found, the performance of the scheme on the line can be measured. After a predetermined period, another Annex A scheme, such as FDM DMT, can be tested. The performance measurement can be performed again. The method of Annex C can then be tested by toggling various communication schemes compliant with Appendix C (step 640). Once all communication schemes have been tested, the CO transceiver can have all the information necessary to determine an ordered list of communication schemes in order of preferred communication schemes.

  After starting, the same general sequence can be performed. Here, the CP transceiver simply acts as a slave of the CO transceiver. A first communication method is attempted. If it is detected that it is the method of Appendix A, the method proceeds to step 625 and communication is started in that communication method. If necessary, the CP transceiver can prepare for a retraining sequence for the current communication scheme (step 630). If the first communication scheme is not the Annex A scheme, step 620 times out and the method 600 can proceed to step 640 and attempt the Annex C scheme. Again, the CP transceiver waits for a period of time for the CO to establish a communication link with the communication method of Annex C. If one is established, thus indicating that the first communication method is that of Appendix C, communication can begin with the first communication method (step 645). Again, if necessary, the CP transceiver can be ready for a retraining sequence for the current communication scheme (step 650).

  In general, the time allocated to steps 620 and 640 can vary, but the allocated time allows for self-synchronization. In other words, there is no need for manual adjustment.

  It should be emphasized that the above-described embodiments of the present invention are merely possible implementations and are set forth for a clear understanding of the principles of the invention. Many changes and modifications may be made to the above-described embodiments of the invention without departing substantially from the spirit and principles of the invention. All such changes and modifications are intended to be included herein within the scope of this disclosure and the present invention and protected by the following claims.

The invention can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present invention. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.
The block diagram which shows the communication system which can provide this invention. FIG. 2 is a block diagram further illustrating the connection between the xDSL modem at the central office of FIG. 1 and the xDSL modem at the customer premises. 6 is a flowchart illustrating a method for initiating and synchronizing communications between a central office transceiver and a remote transceiver performed by an embodiment of the present invention. 6 is a flowchart illustrating a general method of operation of a communication transceiver according to an embodiment of the present invention. FIG. 5 is a flowchart showing a method for setting communication to be executed during the setting mode of the method of operation of FIG. 4. FIG. 5 is a flowchart illustrating a method for retraining performed during a retraining mode of the method of operation of FIG. 6 is a flowchart illustrating a general method for determining a preferred communication scheme according to an embodiment of the present invention. 6 is a flowchart illustrating a general method for synchronizing and training a remote transceiver to communicate in a preferred communication scheme according to an embodiment of the present invention.

Claims (47)

Initiating and synchronizing communication between a central office transceiver configured to communicate in any of a plurality of communication schemes and a remote transceiver configured to communicate in at least one of the plurality of communication schemes A method for
Detecting a remote transceiver communicatively coupled to the central office transceiver;
Determining a preferred communication scheme to be utilized by the central office transceiver and the remote transceiver from the plurality of communication schemes;
Initiating communication between the central office transceiver and the remote transceiver in the preferred communication scheme;
Including methods.   The method of claim 1, further comprising training the central office transceiver and the remote transceiver to communicate in the preferred communication manner.   The method of claim 1, further comprising monitoring communications between the central office transceiver and the remote transceiver.   4. The method of claim 3, further comprising switching a communication scheme utilized by the central office transceiver and the remote transceiver to another of the plurality of communication schemes. The switching step includes
Re-determining different communication schemes utilized by the central office transceiver and the remote transceiver;
Resuming communication between the central office transceiver and the remote transceiver utilizing the different communication scheme;
The method of claim 4 comprising:   The method of claim 1, wherein the central office transceiver and the remote transceiver are digital subscriber line (DSL) transceivers, and the plurality of communication schemes utilize discrete multitone (DMT) line codes. The plurality of DMT communication methods are:
Frequency division multiplexing (FDM) system;
Echo cancellation (EC) overlap method,
A far-end crosstalk bitmap (FBM) system;
Dual bit map (DMB) method,
The method of claim 6 comprising: The plurality of DMT communication methods are:
International Telecommunication Union-Telecommunication Standardization Sector (ITU-T) A communication method conforming to the standard defined by Annex A of the 992 standard;
International Telecommunication Union-Telecommunication Standardization Sector (ITU-T) A communication system conforming to the standard defined by Annex C of the 992 standard;
The method of claim 6 comprising: Determining the preferred communication method comprises:
Testing the plurality of communication schemes for performance characteristics at the central office transceiver and the remote transceiver;
Recording performance characteristics of the plurality of communication methods;
Determining the order of preference of communication schemes including preferred communication schemes based on the performance characteristics;
The method of claim 1 comprising:   The test is based on G. of the International Telecommunication Union-Telecommunication Standardization Sector (ITU-T). The method of claim 9, wherein the method is performed according to a standard defined by 994. The performance characteristics are
Connectivity and
Various communication bit rates,
The method of claim 9 comprising: Determining the preferred communication method comprises:
Communicating a command configured to request initiation in the preferred communication scheme from the central office transceiver to the remote transceiver;
The method of claim 1 comprising:   The method of claim 12, wherein the command is communicated via an Embedded Operations Channel (EOC). A method for operation of a first communication transceiver capable of communicating in a plurality of communication modes, comprising:
Starting an operation in a setting mode so that a preference order of the plurality of communication methods is established;
Switching to retraining if necessary, and retraining with the communication method selected as commanded by the order of preference of the plurality of communication methods;
Communicating with a second communication transceiver in the selected communication scheme;
Including methods. After the subsequent start,
Attempting communication until communication is established in the plurality of communication schemes in the order ordered by the preference order; and
Retraining if necessary,
15. The method of claim 14, further comprising: Said communicating step comprises:
Communicating with the selected communication method;
Monitoring communication between the first transceiver and the second transceiver;
Switching to a setting mode if necessary and re-establishing the order of preference of the plurality of communication methods;
15. The method of claim 14, comprising: 15. The method of claim 14, further comprising switching to a setting mode at any point in operation.   15. The method of claim 14, wherein the first transceiver and the second transceiver are digital subscriber line (DSL) transceivers, and the plurality of communication schemes utilize discrete multitone (DMT) line codes. The plurality of DMT communication methods are:
Frequency division multiplexing (FDM) system;
Echo cancellation (EC) overlap method,
A far-end crosstalk bitmap (FBM) system;
Dual bit map (DMB) method,
The method of claim 18 comprising: The plurality of DMT communication methods are:
International Telecommunication Union-Telecommunication Standardization Sector (ITU-T) A communication method conforming to the standard defined by Annex A of the 992 standard;
International Telecommunication Union-Telecommunication Standardization Sector (ITU-T) A communication system conforming to the standard defined by Annex C of the 992 standard;
The method of claim 18 comprising: A first transceiver configured to communicate in any of a plurality of communication methods;
A second transceiver communicatively coupled to the first transceiver, the second transceiver configured to communicate in at least one of the plurality of communication schemes;
Means for negotiating a preferred communication scheme between the first and second transceivers;
Means for training the first and second transceivers to communicate in the preferred communication scheme, if necessary;
Means for initializing and synchronizing communications between the first and second transceivers in the preferred communication scheme;
A communication system including: Means for monitoring communication between the first and second transceivers;
Means for switching a communication scheme utilized by the first and second transceivers to another of the plurality of communication schemes;
The system of claim 21 further comprising:   23. The system of claim 21, wherein the communication system is a digital subscriber line (DSL) communication system, and the plurality of communication schemes utilize discrete multitone (DMT) line codes. The plurality of DMT communication methods are:
Frequency division multiplexing (FDM) system;
Echo cancellation (EC) overlap method,
A far-end crosstalk bitmap (FBM) system;
Dual bit map (DMB) method,
24. The system of claim 23, comprising: The plurality of DMT communication methods are:
International Telecommunication Union-Telecommunication Standardization Sector (ITU-T) A communication method conforming to the standard defined by Annex A of the 992 standard;
International Telecommunication Union-Telecommunication Standardization Sector (ITU-T) A communication system conforming to the standard defined by Annex C of the 992 standard;
24. The system of claim 23, comprising: Means for alternating attempts to initialize and synchronize communication between a first set and a second set of communication schemes, each attempt being performed for a predetermined period of time Said means;
The preferred communication method is selected by the first transceiver and is included in at least one of the plurality of communication methods of the first set and the second set, and communicates with the preferred communication method. Means for initializing and synchronizing;
The system of claim 21 further comprising: Means for performing a test of the plurality of communication schemes for performance characteristics in the communication system;
Means for recording the performance characteristics of the plurality of communication schemes;
Means for determining an order of preference of communication schemes including the preferred communication scheme based on the performance characteristics;
Means for initializing the start of the communication system utilizing the preferred communication scheme;
The system of claim 21 further comprising:   The test is based on G. of the International Telecommunication Union-Telecommunication Standardization Sector (ITU-T). 28. The system of claim 27, implemented according to a standard defined by 994. The performance characteristics are
Connectivity and
28. The system of claim 27, comprising various communication bit rates. A first transceiver configured to communicate in any of a plurality of communication methods,
Means for communicatively coupling to a second transceiver configured to communicate in at least one of the plurality of communication schemes;
Means for negotiating a preferred communication method;
Means for training the first and second transceivers in the preferred communication scheme;
Means for initializing and synchronizing communications in the preferred communication scheme;
Including the first transceiver. Means for monitoring communication between said first and second transceivers;
Means for switching a communication scheme utilized by the first and second transceivers to another of the plurality of communication schemes;
The first transceiver of claim 30 further comprising:   31. The first transceiver of claim 30, wherein the first and second transceivers are digital subscriber line (DSL) transceivers, and the plurality of communication schemes utilize discrete multitone (DMT) line codes. The plurality of DMT communication methods are:
Frequency division multiplexing (FDM) system;
Echo cancellation (EC) overlap method,
A far-end crosstalk bitmap (FBM) system;
Dual bit map (DMB) method,
The first transceiver of claim 32, comprising: The plurality of DMT communication methods are:
International Telecommunication Union-Telecommunication Standardization Sector (ITU-T) A communication method conforming to the standard defined by Annex A of the 992 standard;
International Telecommunication Union-Telecommunication Standardization Sector (ITU-T) A communication system conforming to the standard defined by Annex C of the 992 standard;
The first transceiver of claim 32, comprising: Said means for negotiating a suitable communication method;
Means for performing a test of the plurality of communication schemes for performance characteristics in the communication system;
Means for recording the performance characteristics of the plurality of communication schemes;
Means for determining an order of preference of communication schemes including the preferred communication scheme based on the performance characteristics;
The first transceiver of claim 30 further comprising:   Said means for carrying out the test is described in G.I. of the International Telecommunication Union-Telecommunication Standardization Sector (ITU-T). 36. The first transceiver of claim 35, which conforms to a standard defined by 994. The performance characteristics are
Connectivity and
Various communication bit rates,
36. The first transceiver of claim 35. Initiates and synchronizes communication between a central office transceiver configured to communicate in any of a plurality of communication schemes and a remote transceiver configured to communicate in at least one of the plurality of communication schemes A program for storing the program stored in a computer-readable medium,
Logic configured to detect the remote transceiver communicatively coupled to the central office transceiver;
Logic configured to determine a preferred communication scheme utilized by the central office transceiver and the remote transceiver;
Logic configured to train communication of the central office transceiver and the remote transceiver in the preferred communication scheme;
Logic configured to initiate communication between the central office transceiver and the remote transceiver using the preferred communication scheme;
Including programs. Logic configured to monitor communications between the central office transceiver and the remote transceiver;
Logic configured to switch a communication scheme utilized by the central office transceiver and the remote transceiver to another of the plurality of communication schemes;
The program according to claim 38, further comprising: The logic configured to perform the switching is
Logic configured to redeterminate different communication schemes utilized by the central office transceiver and the remote transceiver;
Logic configured to resume communication between the central office transceiver and the remote transceiver utilizing a different communication scheme;
40. The program according to claim 39.   40. The program product of claim 38, wherein the central office transceiver and the remote transceiver are digital subscriber line (DSL) transceivers and the plurality of communication schemes utilize discrete multitone (DMT) line codes. The plurality of DMT communication methods are:
Frequency division multiplexing (FDM) system;
Echo cancellation (EC) overlap method,
A far-end crosstalk bitmap (FBM) system;
Dual bit map (DMB) method,
42. The program according to claim 41, comprising: The plurality of DMT communication methods are:
International Telecommunication Union-Telecommunication Standardization Sector (ITU-T) A communication method conforming to the standard defined by Annex A of the 992 standard;
International Telecommunication Union-Telecommunication Standardization Sector (ITU-T) A communication system conforming to the standard defined by Annex C of the 992 standard;
42. The program according to claim 41, comprising: The logic configured to determine the preferred communication method comprises:
Logic configured to test a plurality of communication schemes for performance characteristics at the central office transceiver and the remote transceiver;
Logic configured to record performance characteristics of the plurality of communication schemes;
Logic configured to determine a preference order of communication schemes including the preferred communication scheme based on the performance characteristics;
The program according to claim 38, further comprising:   The logic configured to test the plurality of communication schemes is implemented by G.I. of the International Telecommunication Union-Telecommunication Standardization Sector (ITU-T). 45. The program of claim 44 including logic configured to test according to a standard defined by 994. The performance characteristics are
Connectivity and
Various communication bit rates,
45. The program according to claim 44, comprising: The logic configured to determine the preferred communication method comprises:
40. The program product of claim 38, comprising logic configured to communicate a command configured to request initiation in the preferred communication scheme from the central office transceiver to the remote transceiver.

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