JP2016220121A - OFDM communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an OFDM communication system capable of achieving a high communication speed without causing a communication error even when an interference occurs between apparatuses.SOLUTION: The OFDM communication system includes: SINR estimated value calculation means 43, 47 for calculating an SINR estimated value; multilevel number determination means 44, 48 for determining a multilevel number from the SINR estimated value; and reception power measurement means 36, 37 for measuring reception power and, when determining the multilevel number from the SINR estimated value, utilizes the reception power.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an OFDM communication system that uses a large number of carrier waves (subcarriers) in wired and wireless communication and accommodates a child device in a parent device to perform user data communication.

  In an OFDM (Orthogonal Frequency Division Multiplexing) communication device, the master unit forms a fixed-length frame by transmitting a known signal at a constant period, and the slave unit is subordinately synchronized to this frame. Accommodates the child machine. The communication between the parent device and the child device includes both control information communication for exchanging communication setting information and communication band allocation information and user data communication for exchanging user data.

  In OFDM, communication is performed by placing data on each of a large number of subcarriers. A collection of these subcarriers is called an “OFDM symbol”. Each OFDM symbol avoids interference between OFDM symbols by interposing a period called a guard interval. The amount of information that can be transmitted with one OFDM symbol is the sum of the amount of information carried on each subcarrier.

  In general, user data communication and control information communication often use different communication settings. Each communication setting of user data communication and control information communication means a modulation method corresponding to the number of bits applied to one subcarrier, an error correction method, and the like. Error correction codes such as RS (Reed-Solomon) codes and convolution codes are used for error correction. As a result of these error corrections, even if bit errors occur in some subcarriers, if the amount of errors is within a predetermined range, the errors are corrected and normal communication is possible. If the amount of bit errors exceeds a predetermined range, the communication data is in a state where a part or all of the data is damaged and cannot be read correctly, that is, a CRC (Cyclic Redundancy Check) error.

  In user data communication, the modulation method is often determined according to the communication environment in order to increase the communication rate as much as possible. In order to realize a higher communication rate, modulation scheme adjustment is not performed using the same modulation for all subcarriers, but is performed for each subcarrier, or a plurality of subcarriers are handled as a group. Hereinafter, this adjustment is referred to as “mapping adjustment”. This mapping adjustment is once executed at the time of connection, and thereafter, an environment change is appropriately detected at the time of communication and continuously adjusted.

  On the other hand, control information communication uses a communication method with higher error tolerance due to the nature of sending and receiving communication setting information and the like, and a method that can maintain communication even if some environmental changes occur. Specifically, a low modulation scheme such as BPSK (Binary Phase Shift Keying) that handles only one bit in one subcarrier is used, and the above-described error correction code settings such as RS code and convolutional code are more redundant. Set to a high setting to increase error tolerance. Further, as another method for increasing error tolerance, there is a means for communicating one piece of information using a plurality of subcarriers, such as frequency diversity.

  The connection procedure for user data communication between the parent device and the child device is as follows. First, the child device performs a synchronization process on a signal transmitted from the parent device, and then requests connection to the parent device. After notifying the identification number from the master unit to the slave unit, mapping adjustment for user data communication is performed between the two units. These connection processes are performed using control information communication between the parent device and the child device.

  As a technique related to the present invention, for example, Japanese Patent Application Laid-Open No. 2007-68007 (Patent Document 1) proposes a technique for obtaining a power ratio between interference power and noise power generated in the own network for each subcarrier. Has been.

Japanese Unexamined Patent Publication No. 2007-68007 (FIG. 1 and description thereof)

  In the conventional OFDM communication apparatus, when this apparatus is connected to a plurality of parallel lines (for example, two or more twisted pair lines in an aggregate cable), there is a problem that a communication error occurs due to interference. For example, when emphasizing avoidance of communication errors, it is necessary to perform mapping with a sufficiently large margin, and there is a problem that a high communication speed cannot be obtained.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an OFDM communication system in which a communication error does not occur even when interference occurs between apparatuses and a high communication speed can be obtained. It is what.

  An OFDM communication system according to the present invention is an OFDM communication system in which a slave unit is accommodated in a master unit and communication is performed between the master unit and the slave unit using a plurality of carrier waves, and wiring is connected There is provided a connection means for connecting to a device provided side by side, and a measuring means for measuring received power when connected to the device provided side by side.

  The OFDM communication system according to the present invention includes connection means for connecting to a device provided without connecting wires, and a measurement means for measuring received power when connected to the device provided together. Even when interference occurs, a communication error does not occur, and a high communication speed can be obtained.

It is a figure explaining the OFDM communication system which concerns on Embodiment 1 of this invention, and is a block diagram which shows an example of the function of a main | base station and a subunit | mobile_unit. It is a figure explaining the OFDM communication system which concerns on Embodiment 1 of this invention, and is a figure which shows the connection between apparatuses by a crosstalk signal. It is a figure explaining the OFDM communication system which concerns on Embodiment 1 of this invention, and is a figure which shows an example of the sequence of the mapping process which considered the crosstalk signal. It is a figure explaining the utilization method of the SINR upper limit at the time of interference of the OFDM communication system which concerns on Embodiment 1 of this invention. It is a figure explaining the usage of the subcarrier at the time of control information communication of the OFDM communication system which concerns on Embodiment 1 of this invention. It is a figure explaining the calculation method of the SINR upper limit at the time of interference of the OFDM communication system which concerns on Embodiment 1 of this invention. It is a figure explaining the calculation method of the SINR upper limit at the time of interference of the OFDM communication system which concerns on Embodiment 2 of this invention. It is a figure explaining the calculation method of the SINR upper limit at the time of the OFDM communication system interference which concerns on Embodiment 3 of this invention.

  Preferred embodiments of an OFDM communication system according to the present invention will be described below with reference to the drawings. In each figure, the same reference numerals indicate the same or corresponding parts.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating an OFDM communication system according to Embodiment 1 of the present invention, and is a block diagram illustrating an example of functions of a parent device and a child device.
As illustrated in FIG. 1, the parent device and the child device in the OFDM communication system according to the first embodiment are a reception amplifier 1, a transmission amplifier 2, a demodulation / decoding processing unit 3, a modulation / coding processing unit 4, an SINR estimation. A processing unit 5, a mapping adjustment processing unit 6, a device control unit 7, a transmission / reception data control unit 8, a user data input / output unit 9, and a synchronization processing unit 10 are included. The device control unit 7 includes a sequence control unit 11 and a timeout monitoring control unit 12.

  In FIG. 1, a received signal is demodulated and decoded by a demodulation / decoding processing unit 3 through a reception amplifier 1. From the demodulated and decoded signal, user data and control information are extracted by the transmission / reception data control unit 8, the user data is passed to the user data input / output unit 9, and the control information is passed to the device control unit 7. On the other hand, when user data and control information are input to the transmission / reception data control unit 8 from the user data input / output unit 9 and the device control unit 7, respectively, the data is encoded and modulated by the modulation / coding processing unit 4 and transmitted. It is output via the amplifier 2.

  The device control unit 7 controls the device by controlling the demodulation / decoding processing unit 3, the modulation / coding processing unit 4, the SINR estimation processing unit 5, the mapping adjustment processing unit 6, the transmission / reception data control unit 8, and the synchronization processing unit 10. Control.

  In the device control unit 7, message processing between the parent device and the child device is controlled by the sequence control unit 11, and a message non-delivery is detected by the timeout monitoring control unit 12. When a timeout occurs, processing such as retransmission is executed. The apparatus control unit 7 determines that the connection process has failed, for example, when the message transmission / reception has not succeeded even after the retransmission, and detects the connection process failure. Note that a connection processing flow shown in FIG. 3 described later is controlled (executed) by the device control unit 7.

  When the apparatus is activated, the master unit starts transmission of a control channel necessary for the slave unit to synchronize as connection processing. On the other hand, the slave unit first performs synchronization processing on the master unit by the synchronization processing unit 10 based on the received signal. Thereafter, the connection control including mapping adjustment is controlled (executed) by the apparatus control unit 7 in response to a connection request from the slave unit.

  The SINR estimation processing unit 5 estimates the SINR (Signal to Interference and Noise Ratio) using the received signal. SINR is a signal-to-interference noise ratio, and is expressed as a ratio of the power of the desired terminal to the power of the interference terminal and the noise power, that is, SINR = desired terminal power / interference terminal power + noise power. . Based on the estimated SINR information, the mapping adjustment processing unit 6 calculates a mapping adapted to the SINR, and sets the mapping in the demodulation / decoding processing unit 3 that handles the received signal. At the same time as changing the setting of the own device between the parent device and the child device, this setting is notified to the partner device, so that the partner device sets the modulation / coding processing unit 4 that handles the transmission signal.

Next, signal crosstalk (interference) between OFDM communication apparatuses will be described with reference to FIG.
In FIG. 2, a first master unit 20 and a first slave unit 21, and a second master unit 22 and a second slave unit 23 are connected to each other. They are connected via twisted pair wires 24 and 25, respectively. The twisted pair wires 24 and 25 are wires that are gathered inside the same collective cable 26. In this case, crosstalk (interference) occurs in the vicinity of the two parent devices 20 and 22 as in a region 27 surrounded by a dotted line in FIG. Crosstalk here means that the communication signal of the twisted pair line 24 is also detected on the twisted pair line 25 side that is not directly connected. In FIG. 2, when the level of crosstalk is relatively large, the second master unit 22 is operated as a slave unit for the first master unit 20 by using the second master unit 22 as a signal interference component. And can be accommodated in the first base unit 20. This is because when the crosstalk phenomenon focuses on the signal to be transmitted / received, it can be treated as similar to the attenuation of the signal by normal long-distance transmission, that is, the crosstalk signal except that the signal level is small. This means that the characteristics are not significantly different from those of signals directly connected by twisted pair wires.

A mapping procedure in consideration of interference by the OFDM communication system according to Embodiment 1 configured as described above will be described with reference to FIG. In FIG. 3, the parent device, the (temporary) child device, and the child device are the first parent device 20, the (temporary) child device is the second parent device 22, and the child device is the first child device. This shows the message transmission / reception between the first parent device 20, the second parent device 22, and the first child device 21 in the connection process.
In FIG. 3, the parent device indicates the first parent device 20, the (temporary) child device indicates the second parent device 22, and the child device indicates the first child device 21. Reference numeral 30 is a control communication setting for interference power measurement, reference numeral 31 is a control channel transmission start, reference numeral 32 is a connection request reception process, reference numeral 33 is a synchronization process, reference numeral 34 is a power measurement channel transmission start, and reference numeral 35 is a power measurement. Channel transmission start, symbol 36 is power measurement processing, symbol 37 is power measurement processing, symbol 38 is normal control communication setting, symbol 39 is connection request reception processing, symbol 40 is synchronization processing, and symbol 41 is SINR estimation channel transmission. Start, reference numeral 42 indicates the start of SINR estimation channel transmission, reference numeral 43 indicates Rx side SINR estimation processing (the Rx side will be described later), reference numeral 44 indicates user data mapping determination processing (with SINR upper limit during interference), reference numeral 45 Is the end of SINR estimation channel transmission, 46 is the user data mapping setting change, 47 is the Tx side SINR estimation process (Tx Reference numeral 48 denotes user data mapping determination processing, reference numeral 49 denotes SINR estimation channel transmission end, reference numeral 50 denotes user data mapping setting change, and reference numeral 51 denotes connection processing end. Note that the operation is performed by once interconnecting with another parent device, and then performing normal connection processing.

  First, the flow from the interference power measurement control communication setting 30 to the normal control communication setting 38 will be described. This process is a device that is not directly connected to the parent device via a twisted pair line and that interferes with the communication of this parent device, that is, a device in which the crosstalk signal affects the received signal of this parent device. 2 is a process for connecting the second master unit 22 to the first master unit 20 when the configuration of FIG. 2 is taken as an example, as described above. Note that the second master unit 22 is operated as a slave unit for connection. Here, this slave is a (temporary) slave.

  After the interference power measurement control communication setting 30 for setting the second parent device 22 as a (temporary) child device, etc., at the control channel transmission start 31, the first parent device 20 starts transmission of the control channel. In the control communication setting 30 for measuring interference power, the second master unit 22 is set as a (temporary) slave unit. However, this setting change is not limited to simply changing the operation mode from the master unit to the slave unit. In some cases, setting changes such as a preamble pattern to be added to the head of the symbol are also performed. This is because when a plurality of sets of devices are installed, the above-described preamble pattern or the like may be set differently for each set in order to avoid erroneous connection or the like. The (temporary) slave unit (second master unit 22) detects the control channel transmitted by the first master unit 20 in the synchronization process 33 and performs the initial synchronization process. Note that the temporary child device (second parent device 22) continues the process for maintaining the synchronization with the first parent device 20 after the initial synchronization.

  Next, the temporary slave device (second master device 22) transmits a connection request to the first master device 20 in order to be accommodated in the first master device 20. The first master device 20 that has received the connection request notification in the connection request reception process 32 transmits a connection response to the temporary slave device (second master device 22). Details of processing of the first base unit 20 for receiving a connection request will be described later. The first master unit 20 notifies the temporary slave unit (second master unit 22) of the identification number for identifying the slave unit by this connection response notification. When a plurality of slave units are accommodated in the first master unit 20, the slave units are distinguished by this identification number.

  The temporary child device (second parent device 22) uses the identification number to identify whether the information is addressed to the own device in the notification content from the first parent device 20. As an example, this identification number is used for bandwidth allocation for user data communication.

  Next, after the first master unit 20 transmits a power characteristic measurement start request and the (temporary) slave unit (second master unit 22) transmits a power characteristic measurement start response, the first master unit 20, The (temporary) slave unit (second master unit 22) starts transmission of the power measurement channel at power measurement channel transmission start 34 and 35, respectively. Here, the power measurement channel is a dedicated channel for power measurement. This dedicated channel is the same dedicated channel as the dedicated channel for the above-described SINR estimation. In the present embodiment, a dedicated channel is used, but a normal channel may be used.

  The first master device 20 and the (temporary) slave device (second master device 22) perform power measurement processing at power measurement channel transmission start 34 and 35, respectively. As a result, the first master unit 20 measures the level of the crosstalk signal from the (temporary) slave unit under interference, that is, the second master unit 22, which is a device not directly connected by the twisted pair line 24. be able to. Here, the level of the crosstalk signal is referred to as interference power.

  The processing so far is processing for measuring crosstalk, that is, the degree of interference, specifically, interference power. Processing after the normal control communication setting 38 is a normal processing procedure in an environment without interference. It is almost the same thing. However, the user data mapping determination process (with interference SINR upper limit value) 44, which will be described later, is a unique process when there is interference, and the process without the interference SINR upper limit value here is a normal process.

  Next, the processing after the normal control communication setting 38 will be described. This process is a process of connecting a slave unit to the master unit. As described above, when the configuration of FIG. 2 is taken as an example, the first slave unit 21 is connected to the first master unit 20. It is processing. The first slave unit 21 detects the control channel transmitted by the first master unit 20 in the synchronization process 40 and performs an initial synchronization process. The first slave unit 21 is accommodated in the first master unit 20. Therefore, a connection request is transmitted to the first base unit 20. Note that the first slave unit 21 continues the process for maintaining the synchronization with the first master unit 20 even after the initial synchronization.

  The first master unit 20 that has received the connection request notification in the connection request reception process 39 transmits a connection response to the first slave unit 21. Details of processing of the first base unit 20 for receiving a connection request will be described later. The first parent device 20 notifies the first child device 21 of the identification number for identifying the child device by this connection response notification. When a plurality of slave units are accommodated in the first master unit 20, the slave units are distinguished by this identification number. The first slave unit 21 uses the identification number to identify whether or not the information is addressed to itself in the notification content from the first master unit 20. As an example, this identification number is used for bandwidth allocation for user data communication.

  Next, after the first master unit 20 transmits a mapping adjustment start request and the first slave unit 21 transmits a mapping adjustment start response, the first master unit 20 and the first slave unit 21 perform SINR. At the estimation channel transmission start 41 and the SINR estimation channel transmission start 42, transmission of the SINR estimation channel is started. Here, the SINR estimation channel is a dedicated channel for performing SINR estimation. In this embodiment, a dedicated channel is used, but a normal channel may be used.

  The first master unit 20 and the first slave unit 21 perform the Rx side SINR estimation process and the Tx side SINR estimation process in the Rx side SINR estimation process 43 and the Tx side SINR estimation process 47, respectively. Although not specifically illustrated, the SINR estimation process here may be performed a plurality of times in order to increase the reliability of the estimation result. Here, the Rx side and the Tx side mean a reception direction and a transmission direction when viewed from the parent device.

Based on the estimated SINR estimation result, user data mapping determination processing 44 and 48 determines user data mapping, and transmits a mapping result notification to the partner apparatus. That is, the user data mapping determination processes 44 and 48 serve as multi-value number determination means for determining the multi-value number from the SINR estimated value. The device that has received this notification transmits a mapping result receipt notification. The user data mapping determination process (with an interference SINR upper limit value) 44 is a special process for handling interference, and details will be described later.
Since the mapping result notification may have a relatively large size, it may be divided and notified as appropriate. In the present embodiment, mapping is determined on the side where SINR estimation is performed, and the result is notified to the other side. For example, instead of not reporting the mapping, the SINR estimation result itself is notified and the notification is sent. It is also possible to use a method for determining the mapping on the receiving side. After the transmission and reception of the Rx side and Tx side mapping results are completed, the master unit transmits a mapping adjustment end request, and the slave unit transmits a mapping adjustment end response.

  Next, the first master unit 20 and the first slave unit 21 stop transmission of the SINR estimation channel at the end of transmission of SINR estimation channels 45 and 49, and change to the user data mapping setting change 46 and 50. The user data mapping setting is changed, and the process proceeds to the connection process end 51.

  This mapping change needs to be changed with the same contents on both sides. In other words, it is necessary to change the settings of the Rx side mapping on both sides of the master unit and the slave unit and to change the settings of the Tx side mapping on both sides of the base unit and the slave unit. In the present embodiment, the Rx-side mapping notification is processed first, but there is no problem in another order.

Next, a method for using the interference upper SINR value in the OFDM communication system according to Embodiment 1 will be described with reference to FIG.
In FIG. 4, reference numeral 50 denotes an SINR estimation process, reference numeral 51 denotes a received power measurement process, reference numeral 52 denotes an interference SINR upper limit value calculation, reference numeral 53 denotes an interference power value, and reference numeral 54 denotes a user data mapping determination process. That is, the SINR upper limit value at the time of interference is determined from the received power measurement process 51 and the interference power value 53 as understood from the processing flow indicated by the arrow in FIG.

Next, communication settings for control information communication in the OFDM communication system according to Embodiment 1 will be described with reference to FIG.
FIG. 5 is a diagram comparing normal received power and received power when only interference components are connected. In FIG. 5, the horizontal axis represents frequency and the vertical axis represents received power. The graph shown by the solid line in FIG. 5 is a characteristic of received power when the master unit and the slave unit are connected at a normal long distance. On the other hand, the graph shown by the dotted line shows the power characteristics when only the interference component is connected, and when connected only with the interference component, the low-frequency level is low, contrary to the normal long-distance characteristics. It is. The dashed line drawn horizontally in FIG. 5 indicates the limit reception power. When the reception level is equal to or lower than the dashed line, it means that it cannot be used effectively for communication. Further, in FIG. 5, regions divided by A, B, C, and D indicate divisions called frequency diversity (diversity) branches.

Control communication in the range from the interference power measurement control communication setting 30 to the normal control communication setting 38 in FIG. 3 is performed using a signal having only an interference component indicated by a dotted line in FIG.
In the first embodiment, in the control communication in the range from the interference power measurement control communication setting 30 to the normal control communication setting 38, the area corresponding to the section A is set to be unused, and error correction is performed. The communication settings are changed so that the redundancy is high, and stable communication is realized. This is completely different from the setting after the normal control communication setting 38. If the redundancy of error correction is increased, the efficiency of communication deteriorates, but the communication within the range from the interference power measurement control communication setting 30 to the normal control communication setting 38 is before performing user data communication. A decrease in communication efficiency is not a problem.

  FIG. 6 is a method for calculating the interference SINR upper limit value of the OFDM communication system according to the first embodiment, where the horizontal axis represents frequency and the vertical axis represents power. In FIG. 6, the solid line is the received power Z2, and the dashed line is the interference power measurement value U2. In the first embodiment, the assumed interference power U1 is the same value as the interference power measurement value U2. The interference component is noise when viewed from the original signal, and the interference upper SINR value is obtained by subtracting the assumed interference power U1 from the received power Y2. In FIG. 6, the size of the SINR upper limit value at the time of interference at the frequency f1 is illustrated in the range of the arrows. The presence / absence of interference does not occur when the interference source is not communicating depending on the presence / absence of communication at the interference source, but in order to realize error-free communication, as shown in FIG. It is necessary to assume a state where there is communication. In Embodiment 1, the interference SINR upper limit value is obtained from the measured interference power value and used for user data mapping, but it goes without saying that the steps up to the measurement of the interference power value may be used. . Specifically, the measured value of interference power may be used for determining the quality of the communication environment.

Embodiment 2. FIG.
Next, an OFDM communication system according to Embodiment 2 of the present invention will be described.
FIG. 7 is a diagram for explaining a method of calculating an interference SINR upper limit value in the OFDM communication system according to the second embodiment, where the horizontal axis indicates frequency and the vertical axis indicates power, as in FIG. In FIG. 7, the solid line is the received power Z2, and the one-dot broken line is the interference power measurement value U2. In the second embodiment, the assumed interference power U1 is the maximum value of the interference power measurement value U2.

  Also in the second embodiment, similarly to the first embodiment shown in FIG. 6, the interference SINR upper limit value is obtained by subtracting the assumed interference power U1 from the received power Y2. The second embodiment has a smaller SINR upper limit at the time of interference than that of the first embodiment, and therefore can be said to be less likely to cause an error due to interference. Further, since the assumed interference power is a single value, there is an advantage that management is simplified. On the other hand, the communication rate is inferior to that of the first embodiment. Needless to say, the possibility of occurrence of an error and the communication rate change depending on the setting of a margin or the like.

Embodiment 3 FIG.
Next, an OFDM communication system according to Embodiment 3 of the present invention will be described.
FIG. 8 is a diagram for explaining a method for calculating the SINR upper limit value at the time of interference in the OFDM communication system according to the third embodiment. Like FIG. 6, the horizontal axis represents frequency and the vertical axis represents power. In FIG. 8, the solid line is the received power Z2, and the dashed line is the interference power measurement value U2. In the third embodiment, the assumed interference power U1 is a curve of a specific frequency characteristic, specifically, a gradually increasing characteristic in which the low frequency level is low and the level increases as the frequency increases, and the interference It is assumed that the power measurement value U2 does not exceed any frequency.

  Also in the third embodiment, similarly to the first embodiment shown in FIG. 6, the interference SINR upper limit value is obtained by subtracting the assumed interference power U1 from the received power Y2. The third embodiment is less likely to cause an error due to interference because the SINR upper limit at the time of interference is smaller than that of the first embodiment. Further, since the assumed interference power can be expressed by a characteristic curve that can be expressed by a specific parameter, there is an advantage that management is simplified. On the other hand, the communication rate is inferior to that of the first embodiment. Needless to say, the possibility of occurrence of an error and the communication rate change depending on the setting of a margin or the like.

Next, communication settings will be described. The setting here means a setting such as a modulation scheme, an error correction scheme, and further frequency diversity.
For user data communication, a setting with higher communication efficiency is used by mapping adjustment in the user data mapping determination process 54 based on the SINR estimation process 50 of FIG. In the first embodiment, this mapping adjustment is performed for each subcarrier. The amount of data that can be transmitted in one symbol is determined by the total number of bits determined by the modulation scheme selected for each subcarrier. As this value is larger, highly efficient user data communication is possible, but if the level is not suitable for the SINR of the usage environment, a communication error will occur. For this reason, mapping adjustment using such a SINR estimation processing result is required. This adjustment is processed by the mapping adjustment processing unit 6 shown in FIG.

  On the other hand, communication with control information uses a setting with high error tolerance. Normally, communication of control information increases error tolerance by using a low modulation scheme such as BPSK (Binary Phase Shift Keying). When viewed in units of individual subcarriers, errors may occur even with this modulation method. However, the error correction or frequency diversity effect described above avoids errors or corrects errors to notify control information. Prevent failed communication errors.

  As described above, the first to third embodiments of the present invention have been described. However, the present invention is not limited to this, and these configurations may be appropriately combined or may be combined with the configurations without departing from the spirit of the present invention. It is possible to add partial deformation or to omit part of the configuration.

1 reception amplifier, 2 transmission amplifier, 3 demodulation / decoding processing unit, 4 modulation / coding processing unit, 5
SINR estimation processing unit, 6 mapping adjustment processing unit, 7 device control unit, 8 transmission / reception data control unit, 9 user data input / output unit, 10 synchronization processing unit, 11 sequence control unit, 12 timeout monitoring control unit, 20 first parent Machine, 21 1st child machine, 22 2nd parent machine, 23 2nd child machine, 24, 25 twisted pair wire, 26 collective cable, 27 area

Claims (6)

  In an OFDM communication system that accommodates a slave unit in a master unit and performs communication between the master unit and the slave unit using a plurality of carrier waves, a connection unit that connects to a device provided without connecting wires; An OFDM communication system comprising: a measuring unit that measures received power when connected to the apparatus provided in parallel. Comprising communication setting means for setting communication for connection with the apparatus provided in the above;
2. The OFDM communication system according to claim 1, wherein communication is set for connection when connecting to the apparatus provided side by side without connecting wiring. 3. A SINR estimated value calculating means for calculating a SINR estimated value, a multi-value number determining means for determining a multi-value number from the SINR estimated value, and a received power measuring means for measuring received power,
2. The OFDM communication system according to claim 1, wherein when the multi-value number is determined from the SINR estimation value, received power when connected to the apparatus provided in parallel is used.   The OFDM communication according to claim 3, further comprising means for assuming interference power when determining the multi-value number from the SINR estimated value, wherein the assumed value of the interference power is set as an assumed value of the interference power. system.   4. The method according to claim 3, further comprising means for assuming interference power when determining the multi-value number from the SINR estimated value, wherein the assumed value of the interference power is set to a maximum value of the assumed value of interference power. OFDM communication system.   When determining the multi-value number from the SINR estimated value, a frequency characteristic is provided that includes means for assuming interference power, and the assumed value of the interference power is gradually increased according to a frequency at which the assumed value of the interference power does not exceed the value. 4. The OFDM communication system according to claim 3, wherein the OFDM communication system is a curve.

Images