Method and system for variable state length initialization for DSL systems

ES 2 298 920 T3

DESCRIPTION

Method and system for variable state length initialization for DSL systems.

Background of the invention

Field of the invention

The present invention relates to a method for variable state length initialization in a multicarrier communication system or multicarrier transceiver, to a multicarrier communication system with variable state length initialization, to a multicarrier transceiver with variable state length initialization , to an information storage medium and to a communication protocol for variable state length initialization in a multi-carrier communication system.

The systems and methods of this invention are generally related to communication systems. In particular, the systems and methods of this invention relate to the provision of variable state length initialization.

Description of related technique

In multicarrier modulation, which is also known as Discrete Multitone Transmission (DMT), transceivers gradually pass through a plurality of initialization states before entering steady-state or "show time" communication. In particular, these various initialization states include channel discovery, transceiver training, channel analysis, and the like. These various initialization states allow, for example, the determination of the power levels of the transmitters, the characteristics of the lines, the training of the functions of the receivers, such as equalizers or echo suppressors, or any other characteristic necessary to establish communication, or to change parameters and settings, between transceivers.

DSL (Digital Subscriber Line) modems use variable length initialization states for ADSL communications. The ITU ADSL G.992.1 and G.992.2 standards, incorporated herein by reference in their entirety, specify the operation of conventional ADSL systems. For example, in "Multiple Company Proposal for Initialization", incorporated herein by reference in its entirety, the initialization state C-REVERB1 and the initialization state R-REVERB3 are of variable length. The length of a state is defined as the number of DMT symbols transmitted in that state, where DMT symbols are also known as multicarrier symbols. The length of C-REVERB1 is controlled by the ATU-R (ATU-R - ADSL Transceiver Unit - Remote) and the length of R-REVERB3 is controlled by the ATU-C (ADSL Transceiver Unit - Central Office). In this example, the ATU-C transmitter continues to send C-REVERB1 until the ATU-C receiver detects R-REVERB2 sent from the ATU-R. Similarly, the ATU-R transmitter continues to send R-REVERB3 until the ATU-R receiver detects C-REVERB2 sent from the ATU-C transmitter. For example, when the ATUC receiver has received the R-REVERB3 signal for a sufficient amount of time, the ATU-C transmitter sends the C-REVERB2 signal to the ATU-R, which, once detected by the ATU-R receiver, causes the ATU-R transmitter to exit the R-REVERB3 state. Similarly, when the ATU-R receiver has received the C-REVERB1 signal for a sufficient amount of time, the ATU-R transmitter sends the R-REVERB2 signal to the ATU-C, which, once detected by the ATU-C receiver, causes the ATU-C transmitter to exit the R-REVERB3 state.

It is important that the ATU-R receiver and ATU-C receiver control the length of the states because the ATU-C receiver uses the R-REVERB3 signals and the ATU-R receiver uses the R-REVERB3 signals. C-REVERB1 to execute adaptive signal processing algorithms such as, for example, equalizer training and frame synchronization. In general, this method of having an ATU receiver control the length of an initialization state is used in the ITU standards for ADSL G.992.2 and G.992.1.

However, at least one problem associated with this method is that it does not give the ATU transmitter the ability to control the length of the states. This is problematic, for example, because ATU transmitters can often use these signals to also perform adaptive local signal processing, adaptive analog processing, or the like. For example, the ATU-C transmitter can use the C-REVERB1 signals to train an analog or digital local echo suppressor. In this example, it is important that the ATU-C maintain control of the state longitude, as the ATU-C may not have enough time to complete the echo suppressor training if it is determined and regulated by the ATU-R. .

Accordingly, an illustrative embodiment of this invention allows, for example, the ATU transmitter and ATU receiver to exercise control of the length of one or more initialization states. For example, an ATU transmitter may send information, such as a message, to the ATU receiver before or during a variable-length initialization state. The information may specify, for example, the minimum length of the initialization state as required by the ATU transmitter. As in conventional ADSL modems, the ATU receiver controls the length of the state by sending a predefined signal to the other ATU when the ATU receiver wishes to terminate the state.

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Using the previous example, based on the C-REVERB1 state, before or during the C-REVERB1 state, the ATU-C would send a message to the ATU-R indicating the minimum length of the “MinState” state. For example, the ATU-C might indicate that MinState equals 1000 DMT symbols for C-REVERB1. In this case, the ATU-R would wait at least 1000 DMT symbols before the ATU-R transmitter sent R-REVERB2 to the ATU-C, thus ending the C-REVERB1 state.

Aspects of the invention relate to multi-carrier modulation communications.

Additional aspects of the invention relate to the variation of the lengths of the initialization states in multicarrier communication systems.

Additional aspects of the invention relate to ATU-C and ATU-R controlled initialization state lengths.

Aspects of the invention further relate to transmitter controlled initialization state lengths.

Aspects of the invention further relate to receiver controlled initialization state lengths.

Aspects of the invention further relate to ATU transmitter and / or receiver controlled initialization state lengths.

Aspects of the invention also relate to the exchange of information between transceivers that define state lengths.

Aspects of the invention also relate to advancing a subsequent initialization state based at least on the completion of a variable state-length initialization procedure.

These and other features and advantages of this invention are set forth or apparent from the following detailed description of the embodiments.

Brief description of the drawings

The embodiments of the invention will be discussed in detail with reference to the following figures, in which:

Figure 1 is a functional block diagram depicting an illustrative communication system in accordance with this invention;

Figure 2 is a functional block diagram setting forth illustrative communications between two modems in accordance with this invention;

Figure 3 is a functional block diagram setting forth illustrative communications between two modems in accordance with a second embodiment of this invention;

Figure 4 is a functional block diagram setting forth illustrative communications between two modems in accordance with a third embodiment of this invention;

FIG. 5 is a flow chart outlining an illustrative method of executing variable state length initializations in accordance with this invention; Y

FIG. 6 is a flow chart outlining a second illustrative embodiment of executing variable state length initializations in accordance with this invention.

Detailed description of the invention

Figure 1 shows an illustrative communication system 10. In particular, the communication system 10 comprises a first transceiver 100 and a second transceiver 200, connected by a link 5. The transceiver 100 comprises a state length determination module 110, a status length check module 120, a memory 130, and a message module 140. Transceiver 200 comprises a status length determination module 210, a status length verification module 220, a memory 230, and a message module 240.

Illustrative systems and methods of the invention will be described in relation to a subscriber line, such as a digital subscriber line communication system. However, in order to avoid unnecessarily obscuring the present invention, the description that follows omits well-known structures and devices that may be shown in block diagram form or otherwise summarized. For purposes of explanation, numerous specific details are set forth in order for the present invention to be fully understood. However, it should be appreciated that the present invention can be practiced in a variety of ways beyond these specific details. For example, the systems and methods of this invention can generally be applied to any type of communication system,

ES 2 298 920 T3 including wireless communication systems, such as wireless local area networks (LAN), for example based on IEEE802 systems, power line communications, or any other or combination of systems using multicarrier communications or any form of modulation that has initialization states, the lengths of which are controlled by the transceivers.

Furthermore, while the illustrative embodiments set forth herein show the various components of the assigned communication system, it is to be appreciated that the various components of the system may be located in distant parts of a distributed network, such as a telecommunications network and / or the network. computing world (Internet), or within a dedicated variable state length initialization system. Thus, it should be appreciated that the components of the communication system can be combined into one or more devices and assigned at a particular node in a distributed network, such as a telecommunications network. As will be appreciated from the following description, and for reasons of computing efficiency, the components of the communication system can be arranged anywhere within a distributed network without affecting the operation of the system.

Furthermore, it should be appreciated that the various links connecting the elements may be wired or wireless lengths, or a combination thereof, or any other technical knowledge or later developed elements that are capable of supplying and / or communicating data to and from the devices. connected elements. Additionally, the term "module" as used herein may refer to any technical knowledge or hardware, computer programs or software, or combination of hardware and later developed software that are capable of performing the functions associated with that item.

Communication system 10 in Figure 1 illustrates two transceivers 100 and 200, such as an ATU-C and an ATU-R. Communications between the two transceivers occur over link 5. However, prior to steady state communication between the two transceivers 100 and 200, an initialization has to be performed.

In particular, as described above, initialization is used to train the transceiver which allows, for example, various parameters to be detected and identified, signal processing functions to be trained, details of the communication between the two to be established. transceivers, or the like. However, certain initialization states require that a certain number of DMT symbols be sent and / or received to successfully complete the initialization state training function.

The illustrative embodiments of operation set forth in FIG. 1 will be discussed in connection with an embodiment in which the transceiver 100 is an ATU-C and the transceiver 200 is an ATU-R. In illustrative embodiments of operation, the protocols and methods are used to control the length of the states in which the ATU-C is the transmitting transceiver and the ATU-R is the receiving transceiver. One such example was described above in connection with controlling the length of C-REVERB1. Furthermore, the illustrative embodiment will be discussed in relation to the transceiver 100 determining the minimum number of DMT symbols for the selected state or, alternatively, to the transceiver 200 determining the minimum number of DMT symbols for the selected state or, alternatively, with both transceiver 100 and transceiver 200 determining the minimum number of DMT symbols for the selected state and monitoring the number of DMT symbols received or transmitted as described below.

In particular, in operation, the state length determining module 110 determines the minimum number of DMT symbols for the selected state, if any. Based on the determined MinState value, message module 140 forwards, via communication link 5, the MinState value 50 to transceiver 200. Transceiver 200, in cooperation with status length check module 220 and memory 230, monitors DMT symbols received from transceiver 100. After the status length check module 220 receives at least the minimum number of specified DMT symbols, the status length check module 220 authorizes the transceiver 200 to send a signal to the transceiver 100 such that when the signal is detected by transmitter 100, transceiver 100 will exit the current initialization state and move to a new initialization state. For example, transceiver 200 and transceiver 100 can be pre-programmed to automatically enter a next initialization state based on the signal. Alternatively, transceiver 200 may forward a message, via link 5, to transceiver 100 requesting that the next initialization state be entered.

Alternatively, transceiver 200 may specify a MinState value 25 for a particular initialization state. In particular, the state length determination module 210 determines the minimum number of DMT symbols for a selected state (MinState). Then, in cooperation with message module 240, information identifying the MinState value is forwarded, via link 5, to transceiver 100, which, for example, is stored in memory 130. Next, in cooperation with the state length check module 120, the transceiver 100 monitors the number of DMT symbols transmitted to the transceiver 200 associated with the current initialization state. After the status length check module 120 transmits at least the specified number of DMT symbols, the status length check module 120 authorizes the transceiver 100 to send a signal to the transceiver 200 which, when detected by the receiver from transceiver 200, will indicate to transceiver 200 that the current initialization state has been completed and that a transition to a new initialization state is beginning.

Figure 2 illustrates exchanged communications in accordance with an illustrative embodiment of this invention based on the illustrative C-REVERB1 state described above. In particular, the ATU-C sends information, such as

ES 2 298 920 T3 as a message or identifier, which identifies the MinState value to the ATU-R indicating the minimum length of the state. For example, the ATU-C could send information indicating that the MinState value equals 1000 DMT symbols for the C-REVERB1 250 state. In this illustrative case, the ATU-R, for example, would be required to wait at least 1000 DMT symbols before the ATU-R transmitter could send R-REVERB2 to the ATU-C. Referral of R-REVERB2 to the ATU-C would thereby terminate the C-REVERB1 state.

Alternatively, as illustrated in Figure 3, the ATU-R receiver can send the desired length of the state to the ATU-C transmitter and the ATU-C transmitter can terminate the state, for example, by sending a known signal, such as a reverse polarity (reversed) signal compared to the signal sent in the terminating state to the ATU-R receiver.

Using the C-REVERB1 state from the previous example, the ATU-R would send information, such as an identifier or a message, to the ATU-C indicating the minimum length of state 260, for example, the MinState value. For example, the ATU-R might indicate that the MinState value is equal to 1000 DMT symbols for C-REVERB1. In this case, the ATU-C would be required to wait at least 1000 DMT symbols before the ATU-C transmitter could send a known signal, for example C-SEGUE1, to the ATU-R, thus ending the state C-REVERB1.

Still alternatively, Figure 4 illustrates an illustrative embodiment in which the ATU transmitter and ATU receiver send each other the desired length of states 270 and 280. In this illustrative case, the greater of the two is used. MinState values ​​to determine the transition out of the current state, and therefore there is no need for the signal terminating the state since both transceivers know the duration of the state. However, it is to be appreciated that based on the particular embodiment, it may be desirable to include a status signal termination. As in the previous embodiments, this termination signal can be sent from the ATU-R or the ATU-C.

In operation, using the C-REVERB1 state from the previous example, the ATU-R would send a message to the ATU-C indicating the minimum length of the receiver state (MinState-Rx). For example, the ATU-R could indicate that MinState-Rx would equal 2000 DMT symbols for C-REVERB1. Similarly, the ATU-C could send information, such as a message, to the ATU-R indicating the minimum length of the ATU transmitter state (MinState-Tx). For example, the ATU-C might indicate that MinState-Tx equals 1000 DMT symbols for C-REVERB1. The duration of C-REVERB1 would therefore be equal to the greater of the MinState-TX and MinState-Rx lengths. In this example, the length of C-REVERB1 would be chosen as the greater of the two since it was specified to be 2000 DMT symbols.

Also, it is to be appreciated that while the above embodiments are described in relation to forwarding a single variable state length request from a first transceiver to a second transceiver, it is to be appreciated that it is also possible that one or more of the transceivers specify MinState values ​​for a plurality of states in a single communication to the other transceiver. For example, the MinState values ​​for a plurality of states could be stored in memory and when making a determination to switch to a next initialization state, the transceivers would have the MinState values ​​necessary to ensure that the initialization is correctly completed for the state in question. .

While the illustrative embodiments were described with the transceiver 100 being the ATU-C and the transceiver 200 being the ATU-R, these could be changed such that the transceiver 200 was the ATU-C and the transceiver 100 was the ATU-R. . In this alternative illustrative embodiment, the protocols and methods are used to control the length of the states in which the ATU-R is the transmitting transceiver and the ATU-C is the receiving transceiver. Such an example was described above for the length control of the R-REVERB3.

Figure 5 sets forth an illustrative embodiment for variable state length initialization in accordance with this invention. In particular, control begins at step S100 and continues to step S110. In step S110, a determination is made as to which state (s) requires (s) a minimum number of DMT symbols. Next, in step S120, a first initialization state is selected. Then, in step S130, assuming that the selected state requires a minimum number of DMT symbols, the minimum number of DMT symbols for the selected state is determined. Control then continues to step S140.

In step S140, information, such as a message, specific signal, or identifier, is gathered and forwarded to a second transceiver that specifies the minimum number of DMT symbols for the selected state. Next, in step S150, the number of DMT symbols received or transmitted by the second transceiver associated with the selected state is monitored. Then, in step S160, if the number of received or transmitted DMT symbols is equal to or greater than the MinState length, control continues to step S170. Otherwise, control goes back to step S150.

In step S170, it is determined whether the initialization is complete. If the initialization is complete, control continues to step S180 where the initialization ends and, for example, the transceivers enter into steady state communication. Otherwise, control jumps to step S190 where the information, which may be, for example, a predefined signal, is forwarded to the first transceiver specifying the output of the current initialization state that will allow entry into another initialization state. The control then continues again in step S130.

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Figure 6 outlines a second illustrative embodiment, in which the ATU-C and ATU-R specify a MinState value for a selected state. In particular, control begins at step S200 and continues to step S210. In step S210, it is determined which state (s) requires (s) a minimum number of DMT symbols (MinState). Next, in step S220, a first initialization state is selected. Then, in step S230, the following steps are executed for each of the ATUC and ATU-R.

In particular, in step S240, the minimum number of DMT symbols for the selected state is determined. Next, in step S250, information, such as a message or identifier, is collected and forwarded to the other transceiver specifying the minimum number of DMT symbols for the selected state. Then, in step S260, a comparison is made between the MinState value sent by the ATU-R and the MinState value sent from the ATU-C and the larger of the two MinState values ​​(MaxMinState) is selected. Control then continues to step S270.

In step S270, each of the ATU-C and ATU-R monitors the number of DMT symbols received or transmitted. Next, in step S280, it is determined whether the MaxMinState value has been met. If the MaxMinState value has been satisfied, control continues to step S290. Otherwise, control jumps back to step S270.

In step S290, it is determined whether the initialization is complete. If the initialization is complete, control continues to step S300, where the control sequence ends. Otherwise, control jumps back to step S310 where the ATU-C and ATU-R switch to the next initialization state.

The above-described initialization protocol can be incorporated into a telecommunications device, such as a modem, a DSL modem, an ADSL modem, a multi-carrier transceiver, or the like, or into a separate programmed general-purpose computer having a communications device. However, the systems and methods of this invention can also be incorporated into a special purpose computer, a programmed microprocessor or microcontroller and integrated circuit peripheral elements, an ASIC, or other integrated circuit, a digital signal processor, a logic circuit. or electronic with physical wiring, such as a circuit of individual elements, a programmable logic device, such as a PLD, PLA, FPGA, PAL, a modem, or the like. In general, any device capable of incorporating a state machine that is itself capable of carrying out the flowcharts illustrated herein can be used to implement the variable state length initialization system in accordance with this invention.

In addition, the disclosed methods can be easily implemented in software using object or object-oriented software development environments that provide portable source code that can be used on a variety of computer or workstation hardware platforms. Alternatively, the described variable state length initialization system may be partially or fully incorporated into hardware using standard logic circuits or VLSI design. The use of software or hardware to implement the systems in accordance with this invention depends on the speed and / or efficiency requirements of the system, the particular function, and the particular software or hardware systems or microprocessor systems. or microcomputer used. However, the variable state length initialization systems and methods illustrated herein can be easily incorporated into hardware and / or software, using any technical knowledge or systems or structures, devices and / or software developed later, by persons with normal knowledge of the applicable art from the functional description provided here and with a general basic knowledge of computer and telecommunications techniques.

Furthermore, the described methods can be easily practiced in software running on a programmed general-purpose computer, a special-purpose computer, a microprocessor, or the like. In these cases, the systems and methods of this invention can be incorporated as an integrated program in a personal computer such as JAVA^® or CGI script, as a resource residing on a graphics server or workstation, as a routine built into a receiving transceiver equipped with dedicated variable state length initialization or the like. The variable state length initialization system can also be implemented by physically incorporating the system and method into a software system and / or hardware, such as software systems and hardware of a length initialization enabled transceiver. variable state.