JP4215726B2 - Modem and communication method of modem - Google Patents

Description

  The present invention relates to a modem and a modem communication method, and more particularly, to an ADSL (Asymmetric Digital Subscriber Line) modem and a modem communication method for setting a communication speed based on line quality information in handshaking.

  The ADSL communication system is a digital subscriber line transmission system that uses an existing telephone line wired to a subscriber's house as it is and uses carriers with different frequencies in the upstream and downstream directions. In an ADSL communication system, a handshake for setting communication parameters is executed between a DSLAM (Digital Subscriber Line Access Module), which is a telecommunications carrier facility, and an ADSL modem installed in a user's home. When this handshake is performed, line quality information such as electrical characteristics on the ADSL communication and the state of the communication line is exchanged, and communication is performed at the maximum communication speed of ADSL communication capable of guaranteeing communication quality.

  In addition, after the ADSL communication is started, the error state on the communication line is monitored, and if an error occurs more than a certain level due to external noise or the like, it is determined that the communication quality cannot be guaranteed, and handshaking is performed again. Communication is performed at the maximum communication speed of ADSL communication that can guarantee communication quality based on the line quality information in this handshake. In this case, the maximum communication speed after a new handshake is reduced with respect to the initial maximum communication speed.

  Further, after the ADSL communication is started after that, when the line quality on the communication line is improved, the maximum communication speed of the ADSL communication can be improved. Therefore, a simple DRA (Dynamic Rate Adaptation) function is provided, and automatic communication speed restoration of ADSL communication is possible by performing automatic handshaking of the ADSL modem at an appropriate communication timing.

  An example of an ADSL modem that performs such an operation is disclosed in Patent Document 1. This ADSL modem restarts itself when the communication speed of the data transmitted over the communication line is below the preset minimum communication speed and the communication line has been in a no-communication state for a predetermined time or longer. It operates so as to start communication on the communication line at a predetermined maximum communication speed.

  Patent Document 2 discloses that each of the DSLAM device and the ADSL termination device has a channel quality for each subchannel used in the ADSL line when the channel quality deteriorates during communication between the station-side terminal and the termination-side terminal. And a communication system is disclosed that stops the use of subchannels whose line quality has deteriorated based on the results of the investigation. This communication system can eliminate the occurrence of data error and line disconnection when the line quality deteriorates during communication.

JP 2003-264603 A (FIG. 4) Japanese Patent Laid-Open No. 2004-48213 (FIG. 1)

  However, in the conventional communication system, the maximum communication speed of ADSL communication capable of guaranteeing the communication quality is determined based on the line quality information at the time of executing the handshake. Therefore, after starting ADSL communication, if the line quality on the communication line deteriorates, that is, if the condition on the communication line deteriorates due to external noise, etc., an error of a certain level or more will occur. Therefore, it is determined that the communication quality cannot be guaranteed. Then, handshaking is performed again. For this reason, when ADSL communication is interrupted (ADSL link disconnection occurs) and data is transmitted or received, it is necessary to retransmit the data again in an upper layer such as an application. Or, in the case where data transmission / reception with high real-time characteristics is performed, the data transmission / reception must be abandoned.

  An object of the present invention is to provide an ADSL modem and an ADSL communication method that reduce the occurrence of interruption (ADSL link disconnection) in ADSL communication.

A modem according to one aspect of the present invention is a modem that is connected to a terminal-side device and transmits / receives data to / from the line side, at different points in time when the past n (n is an integer of 1 or more) handshaking is performed. Based on the line quality control unit that holds the line quality information, the communication speed setting unit that sets the communication speed by performing a handshake to communicate with the partner device, and the line quality information that is held in the line quality control unit. A communication speed control unit that controls communication speed setting for the communication speed setting unit, and the line quality information includes a set maximum communication speed and an error occurrence rate in communication at the maximum communication speed. Each time the communication speed setting unit performs the handshake, the communication speed to be set is lowered step by step and the error occurrence rate at each stage. The maximum communication speed corresponding to the error occurrence rate when the measured error occurrence rate falls below at least one of the error occurrence rates held in the line quality control unit is set by the handshake. Communication speed is assumed .

A communication method according to one aspect of the present invention is a communication method in which a modem connected to a terminal side device transmits and receives data to and from the line side, and establishes a communication link with a partner device at a predetermined communication speed. Determining whether or not a communication error rate when establishing the communication link is equal to or greater than a predetermined value; and as a result of the determination, if the error rate is less than the predetermined value, The line quality information at the time of the determination is stored, and when the error occurrence rate is equal to or greater than the predetermined value, the stored past n handshakes (n is an integer of 1 or more) are performed at different times. Based on the line quality information, a step of setting a communication speed by performing a handshake to communicate with the partner apparatus, and a handshake is performed at the set communication speed. The channel quality information is data composed of n sets of a set maximum communication speed and an error occurrence rate in communication at the maximum communication speed, and is set every time the handshake is performed. Decrease the speed step by step and measure the error rate at each step, and the maximum error rate corresponds to the error rate when the measured error rate falls below at least one of the stored error rates The communication speed is the communication speed set by the handshake.

  According to the present invention, since the communication speed is set based on the line quality information monitored periodically, the occurrence of interruption in ADSL communication can be reduced.

  FIG. 1 is a block diagram showing a configuration of an ADSL modem according to an embodiment of the present invention. In FIG. 1, an ADSL modem 10 is connected to a terminal-side device such as a personal computer 40, and sends and receives data to and from the ADSL network 30 via a splitter 20 that separates a voice signal and a data signal. The ADSL modem 10 includes an ADSL interface unit 11, a LAN interface unit 19, a line quality monitoring unit 14, and a main control unit 15.

  The ADSL interface unit 11 includes a communication speed setting unit 12 that sets an appropriate communication speed on the ADSL communication, and a data transmission / reception unit 13 that transmits / receives data to / from the line side in the ADSL communication. Connected to the network 30.

  The main control unit 15 includes a line quality control unit 16 that periodically acquires and stores the line quality information in the ADSL communication monitored by the line quality monitoring unit 14 (a database of line quality information), and a line quality control. The communication speed control unit 17 that determines the communication speed of ADSL communication based on the line quality information stored in the database in the unit 16, and transmission / reception data between the data transmission / reception unit 13 in the ADSL interface unit 11 and the LAN interface unit 19 And a data transmission / reception control unit 18 for controlling the delivery of the ADSL modem 10.

  The ADSL modem 10 first determines the maximum communication speed of ADSL communication capable of guaranteeing communication quality based on the line quality information at that time in the handshake executed for performing ADSL communication, and starts ADSL communication. To do. After the start, the line quality monitoring unit 14 periodically monitors the line quality, and the line quality control unit 16 periodically acquires and stores the line quality information in the ADSL communication.

  Then, when the line quality of ADSL communication is deteriorated, that is, when the state on the communication line is deteriorated due to external noise or the like, the ADSL modem 10 determines that a certain error occurs and the communication quality cannot be guaranteed. At that stage, handshaking is performed again. As for the line quality information when performing the handshake, the communication speed control unit 17 determines the new maximum communication speed of ADSL communication based on the past line quality information stored so far.

  The ADSL modem configured as described above periodically monitors the line quality, periodically acquires and stores the line quality information of the currently connected line, and the maximum communication speed of ADSL communication at the next handshake Reflect in the settings. Since more line quality information is collected over time, more stable communication speed can be set with the passage of time. Hereinafter, a detailed description will be given in accordance with examples.

  In FIG. 1, the ADSL modem 10 first determines the maximum communication speed of the ADSL communication that can guarantee the communication quality based on the line quality information at that time in the handshake executed to perform the ADSL communication. ADSL communication is started. After the start, the line quality monitoring unit 14 periodically monitors the line quality and gives the acquired line quality information to the line quality control unit 16. The line quality control unit 16 statistically analyzes the line quality information in the ADSL communication and stores the line quality information data.

  The communication speed control unit 17 determines the communication speed of ADSL communication based on the line quality information stored in the line quality control unit 16 and instructs the communication speed setting unit 12 about the communication speed. Thereby, the communication speed setting unit 12 sets the communication speed in the data transmitting / receiving unit 13. The personal computer 40 can transmit / receive data to / from the ADSL network 30 through the LAN interface unit 19, the data transmission / reception control unit 18, the data transmission / reception unit 13, and the splitter 20 at a set appropriate communication speed. That is, the ADSL modem 10 optimizes the communication speed for a long time and enables stable and reliable ADSL communication.

  The ADSL modem 10 generates an error exceeding a certain level when the line quality on the communication line monitored by the line quality monitoring unit 14 is deteriorated, that is, when the communication state of the communication line is deteriorated due to external noise or the like. Thus, it is determined that the predetermined communication quality cannot be guaranteed. Then, the data transmission / reception control unit 18 is controlled to perform handshaking again.

  As for the line quality information at the time of performing the handshake, the communication speed control unit 17 is based on the past line quality information by the line quality control unit 16 that stores the data of the line quality obtained by analyzing so far. The maximum communication speed of the new ADSL communication is determined.

  The ADSL modem 10 stores past line quality information and determines the maximum communication speed of ADSL communication based on the past line quality information, so that the occurrence of ADSL link disconnection due to line quality deterioration due to external noise or the like The communication speed is optimized over a long time, and stable and reliable ADSL communication is enabled.

  Next, the operation of the ADSL modem 10 will be described. FIG. 2 is a flowchart showing the operation of the ADSL modem. The ADSL modem 10 first performs handshaking to perform ADSL communication. The line quality monitoring unit 14 monitors the line quality, and the communication speed control unit 17 determines the maximum communication speed of ADSL communication that can guarantee communication quality based on the line quality information at the time of the past handshake execution. The communication speed setting unit 12 sets the determined maximum communication speed (step S11).

  Thereafter, an ADSL communication link is established with the ADSL network 30 from the ADSL interface unit 11 via the splitter 20 at the set maximum communication speed, and ADSL communication is started (step S12).

  After the ADSL communication is started, the ADSL modem 10 periodically monitors the line quality in the line quality monitoring unit 14 for any change in the line quality due to an outpatient or the like (step S13).

  As one of the line quality monitoring methods, the line quality monitoring unit 14 monitors the error occurrence status, and if an error has occurred, a specific error occurrence rate is confirmed (step S14). If an error has occurred, the process proceeds to step S15, and if no error has occurred, the process proceeds to step S16.

  In step S15, the line quality control unit 16 determines whether the error occurrence rate is above or below a certain ratio (here, X%), and if it is below, the error is below the certain ratio X%. Therefore, it is determined that the current communication quality can be guaranteed, and this line quality information and the maximum communication speed of ADSL communication are stored as data as the maximum communication speed of ADSL communication optimized at the present stage (line quality Information database) (step S16), and the series of operations is completed.

  In step S15, if the error rate exceeds a certain ratio, it is determined that an error exceeding the certain ratio X% has occurred and the communication quality cannot be guaranteed, and the data transmission / reception control unit 18 retrains at the determination stage. And handshake is performed again (step S17). Regarding the line quality information when handshaking is performed again, the communication speed control unit 17 determines the new maximum communication speed of ADSL communication based on the past line quality information in the line quality control unit 16 (step S11). ).

  As described above, during the ADSL communication, the ADSL modem 10 periodically monitors the line quality by the line quality monitoring unit 14 for any change in the line quality due to an outpatient or the like. The line quality information of the currently connected line is periodically acquired, statistically analyzed by the line quality control unit 16, and stored as data. When the next handshake is performed, the communication speed control unit 17 determines a new maximum communication speed of ADSL communication based on the line quality information stored so far.

  As a specific example, in a certain ADSL communication, when the maximum communication speed of ADSL communication is A [kbps] and the error occurrence rate is S [%] (> X [%]), the communication quality Therefore, retraining is started at that stage, and handshaking is performed again.

  At this time, the previous maximum communication speed A [kbps] and the error occurrence rate S [%] are stored as data and statistically analyzed, so that this parameter cannot guarantee the communication quality in the previous line state. Judge. When this handshake is performed, control is performed so that B [kbps] equal to or lower than A [kbps] is set as the maximum communication speed of ADSL communication.

  In this way, by periodically monitoring the line quality and setting the maximum communication speed for stable ADSL communication during the next handshake, the possibility of causing ADSL link disconnection due to line quality deterioration due to outpatients, etc. is reduced In addition, stable and highly reliable ADSL communication is possible while maintaining a proper communication speed for a long time.

Next, the method for setting the maximum communication speed of ADSL communication in the above example will be described in more detail. When the maximum communication speed determined in the first handshake is A [kbps], the ADSL modem 10 starts ADSL communication at the maximum communication speed A [kbps]. After the start, the ADSL modem 10 periodically monitors the line quality in the line quality monitoring unit 14 for any change in the line quality due to external noise or the like, and sets the error occurrence rate at that time to S [%]. If the error occurrence rate is S [%] (> X [%]), it is determined that the communication quality cannot be guaranteed. Then, retraining is started at the judgment stage, and handshaking is performed again. The maximum communication speed determined in the second handshake is B [kbps], and the error rate at that time is T [%]. For example, when this is repeated 5 times and the error rate W falls below X [%], it is assumed that the following data is obtained.
First handshake: Maximum communication speed A [kbps], error rate S [%] (> X [%])
Second handshake: Maximum communication speed B [kbps], error rate T [%] (> X [%])
Handshake third time: Maximum communication speed C [kbps], error rate U [%] (> X [%])
Handshake 4th time… Maximum communication speed D [kbps], error rate V [%] (> X [%])
Handshake 5th time… Maximum communication speed E [kbps], error rate W [%] (<X [%])
In this example, since handshaking is always triggered by the fact that the error occurrence rate is larger than X [%], the relationship between the maximum communication speeds is A>B>C>D> E.

  In this way, from the relationship with the error occurrence rate in ADSL communication, it is possible to find a communication speed that enables more stable communication by gradually decreasing the maximum communication speed in stages. Therefore, occurrence of ADSL link disconnection can be reduced.

In the above example, the maximum communication speed at the time of the previous handshake is controlled to set the maximum communication speed of the lower ADSL communication at the time of the next handshake, but the optimization method is It may be other than that. For example, regarding the setting method of the maximum communication speed, if the data by each handshake is as follows,
First handshake: Maximum communication speed A [kbps], error rate S [%]
Second handshake: Maximum communication speed B [kbps], error rate T [%]
Handshake third time: Maximum communication speed C [kbps], error rate U [%]
Handshake 4th time… Maximum communication speed D [kbps], error rate V [%]
Handshake 5th time… Maximum communication speed E [kbps], error rate W [%]
The maximum communication speed F [kbps] determined in the next handshake may be an average of F [kbps] = (A + B + C + D + E) / 5.

  In such a setting method, the maximum communication speed can be appropriately restored even if the maximum communication speed is once lowered due to the instantaneous deterioration of the line quality due to the outpatient.

  As described above, the ADSL modem of this embodiment periodically monitors the line quality in ADSL communication and reflects it in the setting of the maximum communication speed of ADSL communication at the next handshake. Thereby, as time passes, more line quality information can be collected during that time, and a more appropriate maximum communication speed of ADSL communication can be set with the passage of time. Therefore, occurrence of ADSL link disconnection in the ADSL communication system can be reduced.

It is a block diagram which shows the structure of the ADSL modem which concerns on the Example of this invention. It is a flowchart which shows operation | movement of the ADSL modem based on the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ADSL modem 11 ADSL interface part 12 Communication speed setting part 13 Data transmission / reception part 14 Line quality monitoring part 15 Main control part 16 Line quality control part 17 Communication speed control part 18 Data transmission / reception control part 19 LAN interface part 20 Splitter 30 ADSL line network 40 Personal computer

Claims (4)

In a modem that is connected to the terminal side device and sends / receives data to / from the line side,
A line quality control unit for holding line quality information at different points in time when the past n (n is an integer of 1 or more) handshaking is performed ;
A communication speed setting unit that sets a communication speed by performing a handshake to communicate with a partner apparatus;
Based on the line quality information held in the line quality control unit, a communication speed control unit that controls setting of a communication speed for the communication speed setting unit;
With
The line quality information is data consisting of n sets of a set maximum communication speed and an error occurrence rate in communication at the maximum communication speed ,
Each time the communication speed setting unit performs the handshake, the communication speed to be set is lowered stepwise and the error occurrence rate at each step is measured. The measured error occurrence rate is held in the line quality control unit. A modem characterized in that a maximum communication speed corresponding to an error occurrence rate when it falls below at least one of a certain error occurrence rate is a communication rate set by the handshake . The modem according to claim 1 is an ADSL (Asymmetric Digital).
Subscriber Line) A modem characterized by being a communication modem. A communication method in which a modem connected to a terminal side device transmits and receives data to and from the line side,
  Establishing a communication link with a partner device at a predetermined communication speed;
  Determining whether a communication error rate when establishing the communication link is equal to or greater than a predetermined value;
  As a result of the determination, if the error occurrence rate is less than the predetermined value, the line quality information at the time of the determination is stored, and if the error occurrence rate is greater than or equal to the predetermined value, the stored past a step of setting a communication speed by performing a handshake to communicate with a counterpart device based on line quality information at different points in time when n (n is an integer of 1 or more) handshaking;
  Performing handshaking at the set communication speed;
Including
  The line quality information is data consisting of n sets of a set maximum communication speed and an error occurrence rate in communication at the maximum communication speed,
  Each time the handshake is performed, the communication speed to be set is lowered step by step and the error occurrence rate at each step is measured, and the measured error occurrence rate falls below at least one of the stored error occurrence rates. A communication method characterized in that a maximum communication speed corresponding to an error occurrence rate is a communication speed set by the handshake. The communication method according to claim 3 is an ADSL (Asymmetric Digital).
A communication method characterized by being a communication method in Subscriber Line).

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