JP2010130261A - Communication device, and method of determining modulation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To execute communication by a modulation method suitable for a communication quality value which considers the situation of the change of the communication quality value, in a communication device for executing communication by adaptive modulation. <P>SOLUTION: A base station device 101 includes: a communication quality value storage part 105 for acquiring and storing a communication quality value representing quality of communication executed between a communication counterpart and the base station device; a reference period determination part 106 for determining a reference period based on a communication quality value in a period included between a time before a predetermined period and the present; and a modulation method determination part 107 for determining a modulation method applied to the communication based on the communication quality value in the period from the time before the reference period to the present. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a communication apparatus and a modulation scheme determination method, and more particularly to a communication apparatus and a modulation scheme determination method that perform communication by adaptive modulation.

  A communication apparatus that performs communication by adaptive modulation determines a data modulation method in communication according to communication quality. An adaptive modulation system is described in Patent Document 1, for example.

  Such a communication apparatus determines the modulation method based on the average of the communication quality values indicating the communication quality in the most recent predetermined period.

For example, the communication apparatus determines a modulation scheme based on an average value of SINR (Signal to Interference and Noise Ratio) values acquired in a past predetermined period. FIG. 3 is a diagram illustrating a relationship between an SINR value and each modulation class (CMC: Current Modulation Class) in which a modulation method and a transmission data rate determined by the SNR value are defined. In FIG. 3, the SINR value defined for each modulation class is an SINR value indicating the required quality in communication performed in each modulation class. When an SINR value equal to or greater than this value is obtained, the modulation scheme is Selected.
JP 2006-14205 A

  However, in mobile communication, the communication quality is changing rapidly with a sudden change in the communication environment due to the movement of an obstacle or a communication device as a communication partner. Therefore, a communication apparatus that determines a modulation scheme based on the average value of communication quality values described above may not be able to determine a modulation scheme that is suitable for the communication environment when the communication quality changes rapidly.

  For example, when the communication quality is temporarily very low and then suddenly recovers to a very high communication quality, it is actually suitable for high communication quality, for example, communication using a modulation method with a high modulation multi-level number. However, since the average value of the communication quality values becomes low due to the influence of the past low communication quality value, the determined modulation scheme is also a modulation scheme with a low number of modulation multi-values.

  Also, when the communication quality temporarily becomes very high and then suddenly recovers to a very low communication quality, it is actually a communication with a low modulation multi-level modulation method suitable for low communication quality. Even if it cannot be executed, the average value of the communication quality value becomes high due to the influence of the past high communication quality value. It occurs frequently.

  The present invention has been made in view of the above problems, and in a communication apparatus that performs communication by adaptive modulation, performs communication using a modulation scheme suitable for the communication quality value, taking into account the state of change of the communication quality value. With the goal.

  In order to solve the above problems, a communication apparatus according to the present invention includes a communication quality value acquisition unit that acquires a communication quality value indicating the quality of communication performed with a communication partner, and a predetermined period before and to the present. Reference period determining means for determining a reference period based on the communication quality value in a period included in the period, and modulation applied in the communication based on the communication quality value in a period from before the reference period to the present Modulation scheme determining means for determining a scheme.

  ADVANTAGE OF THE INVENTION According to this invention, the communication apparatus which concerns on this invention can perform the communication by the modulation system suitable for the communication quality value also considering the condition of the change of a communication quality value.

  Further, in the communication apparatus according to the present invention, the reference period determining unit determines the reference period when a change amount of the communication quality value in a period included between the predetermined period and the present is less than a predetermined amount. When the amount of change in the communication quality value in the period included between the predetermined period and the present is determined to be the first period, the reference period is set to a second shorter than the first period. Decide on the period.

  In the communication device according to the present invention, the first period is equal to the predetermined period.

  Furthermore, in the communication apparatus according to the present invention, the second period is a period after the time point when the change in the communication quality value is greater than or equal to the predetermined amount, which is included in the predetermined period.

  ADVANTAGE OF THE INVENTION According to this invention, the communication apparatus which concerns on this invention can perform communication by a suitable modulation system with respect to a communication quality value, even when a communication quality value changes rapidly.

  Further, in the communication apparatus according to the present invention, the modulation scheme determining means determines the modulation scheme based on an average value of the communication quality values at the present before the reference period.

  Further, in the communication device according to the present invention, the communication quality value is a value obtained based on a signal transmitted from the communication device and received by the communication partner, and the modulation method is transmitted from the communication device to the communication device. This is a modulation method of a signal transmitted to the other party.

  Further, in the communication device according to the present invention, the communication quality value is a value obtained based on a signal transmitted from the communication partner and received by the communication device, and the modulation scheme is transmitted from the communication partner. This is a modulation method of a signal transmitted to the apparatus.

  The modulation method determining method according to the present invention includes a step of obtaining a communication quality value indicating the quality of communication performed with a communication partner, and the communication in a period included between a predetermined period before and the present. Determining a reference period based on a quality value, and determining a modulation scheme applied in the communication based on the communication quality value in a period from before the reference period to the present.

  In the present embodiment, a base station apparatus in which a modulation scheme is determined based on an average of SINR values in a period determined based on a change state with reference to a change state of a communication quality value in a most recent predetermined period The structure of is shown.

  FIG. 1 is a diagram showing a configuration of a base station apparatus 101 according to the present invention. Base station apparatus 101 communicates with a mobile station apparatus.

  FIG. 7 is a diagram illustrating communication performed by the base station apparatus 101 according to the present embodiment and a mobile station apparatus that is a communication partner. The mobile station apparatus and the base station apparatus 101 transmit uplink signals 701, 703, 705, and 707 and downlink signals 702, 704, 706, and 708 alternately in each frame.

Mobile station apparatus, the frame _{i n (i} n = odd number), notifies the SINR error report indicating the communication quality of the downlink signal received from the base station apparatus 101 in the second previous frame, the base station apparatus 101 in uplink signal 701 To do.

The base station apparatus 101 determines the downlink signal modulation scheme based on the notified SINR error report, and notifies the mobile station apparatus with the downlink signal 704 in the frame i _{n + 1} (i _{n + 1} = even number). The downlink signal 704 is transmitted after being modulated by the same modulation method as the downlink signal 702.

  The base station apparatus 101 performs modulation using the modulation scheme determined above from the modulation processing of the downlink signal 706.

Further, the mobile station apparatus calculates the communication quality of the downlink signal 702, and notifies the base station apparatus 101 of the obtained SINR error report with the uplink signal 705 in the frame i _{n + 2} (i _{n + 2} = odd number).

The base station apparatus 101 determines the downlink signal modulation scheme based on the notified SINR error report, and notifies the mobile station apparatus with the downlink signal 708 in the frame i _{n + 3} (i _{n + 3} = even number). The downlink signal 708 is modulated and transmitted by the same modulation method as the downlink signal 706.

  By repeating the above processing, the base station apparatus 101 determines a downlink signal modulation scheme based on the SINR error report notified from the mobile station apparatus.

  Next, the configuration of base station apparatus 101 will be described below. The base station apparatus 101 includes a radio communication unit 102, a demodulation unit 103, a decoding unit 104, a communication quality value storage unit 105, a reference period determination unit 106, a modulation scheme determination unit 107, an encoding unit 108, a modulation unit 109, a memory 110, An antenna 111 is included. Among these, the demodulation part 103, the decoding part 104, the communication quality value memory | storage part 105, the reference period determination part 106, the modulation system determination part 107, the encoding part 108, and the modulation | alteration part 109 are comprised by CPU or DSP, for example.

  Antenna 111 receives a signal transmitted from a mobile station apparatus that is a communication partner of base station apparatus 101, and outputs the signal to radio communication section 102. The antenna 111 transmits a signal input from the wireless communication unit 102 as a radio wave.

  The wireless communication unit 102 includes a low noise amplifier, a power amplifier, a local oscillator, a mixer, a filter, and the like. The radio communication unit 102 performs processing such as down-conversion and amplification on the signal input from the antenna 111 and outputs the obtained signal to the demodulation unit 103. In addition, the wireless communication unit 102 performs processing such as up-conversion on the signal input from the modulation unit 109 and outputs the obtained signal to the antenna 111.

  The demodulator 103 includes an A / D converter, a serial / parallel converter, an FFT calculator, a parallel / serial converter, and the like. Demodulation section 103 performs processing such as A / D conversion, serial-parallel conversion, discrete Fourier transform, parallel-serial conversion on the signal input from radio communication section 102 and outputs the obtained signal to decoding section 104. .

  Decoding section 104 generates reception data from the signal input from demodulation section 103 and outputs the received data obtained to communication quality value storage section 105 and an upper layer (not shown).

  The communication quality value storage unit 105 acquires SINR target values and stores the latest five SINR target values (the latest 10 frames). The SINR target value is an SINR value of a signal transmitted from the base station apparatus 101 received by the mobile station apparatus that is a communication partner, and is a signal (reception received from the mobile station apparatus and received by the base station apparatus 101). Data).

  As shown in FIG. 3, in communication using adaptive modulation performed by the base station apparatus 101, an SINR value (required SINR value) required for each modulation class, that is, for each modulation method corresponding to the modulation class is specified. Has been. When the mobile station apparatus receives the signal transmitted from the base station apparatus 101, the mobile station apparatus calculates, based on the received signal, the SINR value of the signal and the required SINR value in the modulation scheme (modulation class) in which the signal is modulated. A SINR error report, which is a difference, is calculated once every two frames and transmitted to the base station apparatus 101. The communication quality value storage unit 105 calculates the SINR target value from the received SINR error report using Equation (1).

  SINR target value = required SINR value-SINR error report (1)

  The communication quality value storage unit 105 stores the five latest values of the SINR target value thus obtained, that is, the values of the last 10 frames. Details of the operation of the communication quality value storage unit 105 will be described later.

  Based on the communication quality value stored in the communication quality value storage unit 105, the reference period determination unit 106 determines a reference period that is a parameter for determining the modulation scheme. Details of the operation of the reference period determination unit 106 will be described later.

  Based on the communication quality value stored in communication quality value storage section 105, modulation scheme determining section 107 determines the modulation scheme (modulation class) applied in the modulation of the downlink signal transmitted by base station apparatus 101. This modulation scheme is determined using the reference period determined by the reference period determining unit 106. The determined modulation scheme is notified to the modulation unit 109 and also to the mobile station apparatus via a downlink signal. Details of the operation of the modulation scheme determination unit 107 will be described later.

  Encoding section 108 performs an encoding process on the transmission data transmitted from base station apparatus 101 and outputs the obtained signal to modulation section 109.

  Modulation section 109 modulates the data input from encoding section 108 based on the modulation scheme notified from modulation scheme determination section 107 and outputs the obtained data to radio communication section 102.

  The memory 110 includes a semiconductor memory or a hard disk, and stores data processed by the base station apparatus 101, parameters used, and the like. For example, the memory 110 stores the relationship between the modulation class and the SINR value shown in FIG.

  Here, operations of the communication quality value storage unit 105, the reference period determination unit 106, and the modulation scheme determination unit 107 will be described in detail.

  The communication quality value storage unit 105 calculates and stores the SINR target value from the SINR error report included in the data transmitted from the mobile station apparatus. The communication quality value storage unit 105 has, for example, a FIFO structure. FIG. 2 is a schematic diagram illustrating a structure of the communication quality value storage unit 105 that stores SINR target values. When the SINR target value is calculated, the variables VAR [0] to VAR [4] are shifted one step to the right (in the direction in which the argument increases), and the calculated SINR target value is newly set as VAR [0]. Remembered. Thus, SINR target values for the most recent predetermined period (in this embodiment, corresponding to five, that is, 10 frames) are always stored as VAR [0] to VAR [4].

  The reference period determination unit 106 refers to the SINR target value stored in the communication quality value storage unit 105. At this time, the reference period determining unit 106 refers to the amount of change between the SINR target value in a specific frame included in the most recent predetermined period and the SINR target value acquired immediately thereafter included in the most recent predetermined period. is doing. Then, it is determined whether the amount of change between the two SINR target values is equal to or greater than a predetermined amount (10 dB in the present embodiment).

  Then, when the change amount of the SINR target value is less than 10 dB, the reference period determining unit 106 determines the reference period as a period (first period) equal to a predetermined period (five SINR target values, that is, 10 frames). To do. On the other hand, when the change amount of the SINR target value is 10 dB or more, the reference period determination unit 106 determines the reference period as a period (second period) from the time when the predetermined amount of change ends to the present.

  Modulation method determination section 107 calculates an average value of the values determined by reference period determination section 106 among the SINR target values stored in communication quality value storage section 105, and modulates based on this average value. Determine the method.

FIG. 4 is a diagram illustrating an example of a change in SINR target value. In FIG. 4, frame numbers i ₁ , i ₃ , i ₅ , i ₇ ,... Are odd numbers added by two. Since the SINR error report is transmitted in odd frames, FIG. 4 also shows only for odd frames. A case where communication capable of obtaining the SINR target value shown in FIG. 4 is performed will be described.

When the data of the frame i ₉ is received, the communication quality value storage unit 105 stores the SINR target values of the frames i ₁ to i ₉ as VAR [4] to VAR [0].

  The reference period determination unit 106 refers to these values stored in the communication quality value storage unit 105 and determines whether a change of 10 dB or more has occurred. In this case, since a change of 10 dB or more has not occurred, the reference period determining unit 106 sets the reference period to a period corresponding to five SINR target values, that is, 10 frames, and notifies the modulation scheme determining unit 107 of the period.

  Modulation scheme determination section 107 calculates the average value of SINR value target values for the period notified from reference period determination section 106, that is, 10 frames (five), and determines the modulation scheme based on this average value. Since the average value is (6.2 + 5.7 + 6.0 + 6.2 + 6.4) /5=6.1 dB, the modulation scheme is a modulation scheme corresponding to the modulation class 3 according to the relationship shown in FIG.

Next, when the data of the frame i ₁₁ is received, the communication quality value storage unit 105 stores the SINR target values of the frame i ₃ to the frame i ₁₁ as VAR [4] to VAR [0].

Since the SINR target value has changed by 10 dB or more from frame i ₃ to frame i ₁₁ , the reference period determining unit 106 sets the reference period to one SINR target value that is a period from when the change ends. Is determined to be a period corresponding to, i.e., 2 frames, and notified to the modulation scheme determination unit 107.

The modulation scheme determination unit 107 calculates the average value of the period notified from the reference period determination unit 106 and determines the modulation scheme based on the average value. Here, since the reference period is two frames, the modulation scheme determination unit 107 determines the modulation scheme based on the value 20.2 dB of the frame i ₁₁ stored in VAR [0]. The modulation scheme to be determined is a modulation scheme corresponding to the modulation class 8 according to the relationship shown in FIG.

Next, when the data of the frame i ₁₃ is received, the communication quality value storage unit 105 stores the SINR target values of the frame i ₅ to the frame i ₁₃ as VAR [4] to VAR [0].

Since the SINR target value has changed by 10 dB or more from frame i ₅ to frame i ₁₃ , the reference period determining unit 106 changes the reference period to two SINR target values that are periods from the end of the change. The corresponding period, that is, 4 frames is determined, and the modulation scheme determining unit 107 is notified.

  The modulation scheme determination unit 107 calculates the average value of the SINR target values for the period notified from the reference period determination unit 106, that is, four frames, and determines the modulation scheme based on the average value. Since the average value is (VAR [0] + VAR [1]) / 2 = (20.2 + 21.0) /2=20.6 dB, the modulation scheme corresponds to the modulation class 8 according to the relationship shown in FIG. It becomes a modulation system.

  The above process is repeated, and when the change of 10 dB or more comes before the latest predetermined period (10 frames), the reference period determination unit 106 sets the reference period to 10 frames again.

  FIG. 5A is a diagram illustrating the modulation scheme determination processing performed by the base station apparatus 101 according to the present embodiment described above. FIG. 5B is a diagram illustrating modulation scheme determination processing performed by the base station apparatus according to the related art. It can be seen that the modulation scheme of base station apparatus 101 according to the present embodiment responds faster to changes in the SINR value than in the case of the prior art.

  Next, modulation scheme determination processing performed in base station apparatus 101 according to the present embodiment will be described using a flowchart. FIG. 6 is a flowchart showing modulation scheme determination processing performed in base station apparatus 101 according to the present embodiment.

When the base station apparatus 101 receives the data of the frame _{i n} from the mobile station apparatus (S601), the communication quality value storage unit 105, the frame number of the received data or to confirm odd (S602). If it is an odd number (corresponding to Yes in S602), the communication quality value storage unit 105 calculates the SINR target value from the SINR report included in the received data, and is stored as VAR [0] to VAR [4]. The SINR target value being updated is updated (S603). If the frame number of the received data is not an odd number (corresponding to No in S602), the communication quality value storage unit 105 waits for reception of the next data.

  When the SINR target value stored in the communication quality value storage unit 105 is updated, the reference period determination unit 106 checks whether a change of 10 dB or more has occurred in these values (S604).

  If no change of 10 dB or more has occurred (corresponding to No in S604), the reference period determining unit 106 determines the reference period as 10 frames (S606). On the other hand, if a change of 10 dB or more has occurred (corresponding to Yes in S604), the reference period determining unit 106 determines that the reference period is a period from when the change of 10 dB or more has ended (S605).

  The modulation scheme determination unit 107 calculates an average value of VAR [j] (j is a value within the reference period), that is, an average value of SINR target values in the reference period determined by the reference period determination unit 106 ( S607) A modulation class is determined, and a modulation method corresponding to the modulation class is determined (S608).

  The base station apparatus 101 confirms whether the received frame data is the last data (S609). If it is the last, the process ends, and if it is not the last, it waits for the reception of the next data.

  With the configuration described above, the base station apparatus 101 can execute communication using a modulation scheme suitable for the communication state, taking into account the change state of the communication quality value.

  For example, even when the SINR target value changes abruptly, the base station apparatus 101 can execute communication using a modulation scheme with an appropriate modulation multilevel number for the SINR target value.

  It is needless to say that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

  For example, in the present embodiment, a configuration is shown in which it is determined whether a change of 10 dB or more has occurred in the five most recent SINR target values. However, the number of SINR target values to be referred to and the reference change amount are set to these values. It is not limited.

  In the present embodiment, the predetermined period and the first period have the same number of frames. However, the present invention is not limited to this, and the predetermined period is the period set in the first period (the number of frames). ) It may be the following. In this case, the first period is a predetermined period (the number of frames), and the second period is a period after the time point when the change of the SINR target value exceeds a predetermined amount.

  Furthermore, in the present embodiment, the configuration in which the reference period is changed when a sudden change occurs between two consecutive SINR target values is shown. However, the present invention is not limited to this, and three or more SINR targets are used. It is possible to change to a configuration in which the reference period is changed when the total amount of change in value exceeds a predetermined amount.

  In the present embodiment, the configuration using the SINR value and the SINR target value as the communication quality value is shown. However, the present invention is not limited to this, and can be applied to a configuration using, for example, an SN ratio or an error rate. is there.

  Moreover, although the case where the communication quality value is rapidly improved has been described in the present embodiment, the present invention is not limited to this, and the reference period is similarly determined even when the communication quality value rapidly decreases. Thus, the same effect can be obtained.

  Furthermore, in the present embodiment, the configuration for the case where the communication quality value changes rapidly has been shown, but the present invention is not limited to this, and various configurations that change the reference period according to the tendency of the communication quality value. including.

  Further, in the present embodiment, the configuration has been described in which the reference period is set to the period from the end of the change when a change of a predetermined amount or more occurs, but the present invention is not limited to this, and the normal period If the configuration is changed to a period shorter than the reference period, the effect can be obtained.

  In the present embodiment, the SINR target value is obtained based on a signal transmitted from the base station apparatus and received by the mobile station apparatus, and transmitted from the base station apparatus to the mobile station apparatus based on the obtained SINR target value. Although the configuration for determining the modulation method of the signal to be processed is shown, the present invention is not limited to this. For example, a modulation scheme of a signal transmitted from the mobile station apparatus to the base station apparatus based on the obtained SINR target value is obtained based on a signal transmitted from the mobile station apparatus and received by the base station apparatus. It is good also as a structure to determine.

  Further, in the present embodiment, the configuration in which the present invention is applied to a base station apparatus in a mobile communication system has been described. However, the present invention is not limited to this, and is based on the communication status regardless of wireless or wired. The present invention can be applied to any communication device that determines a modulation method.

It is a figure which shows the structure of the base station apparatus which concerns on this invention. It is a schematic diagram which shows the structure which memorize | stores SINR target value of a communication quality value memory | storage part. It is a figure which shows the relationship between a SINR value and a modulation class. It is a figure which shows an example of the change of a SINR target value. It is a figure which shows the determination method of the modulation system performed by the base station apparatus which concerns on this Embodiment. It is a figure which shows the determination method of the modulation system performed by the base station apparatus which concerns on a prior art. It is a flowchart which shows the determination process of the modulation system performed with the base station apparatus which concerns on this Embodiment. It is a figure which shows the communication performed by the base station apparatus and mobile station apparatus which concern on this Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 101 Base station apparatus, 102 Wireless communication part, 103 Demodulation part, 104 Decoding part, 105 Communication quality value storage part, 106 Reference period determination part, 107 Modulation system determination part, 108 Encoding part, 109 Modulation part, 110 Memory, 111 Antenna, 701 Up signal, 702 Down signal, 703 Up signal, 704 Down signal, 705 Up signal, 706 Down signal, 707 Up signal, 708 Down signal

Claims (8)

Communication quality value acquisition means for acquiring a communication quality value indicating the quality of communication performed with a communication partner;
A reference period determining means for determining a reference period based on the communication quality value in a period included between a predetermined period before and the present;
A modulation scheme determining means for determining a modulation scheme applied in the communication based on the communication quality value in the period from the reference period to the present period;
A communication device comprising: The communication device according to claim 1,
The reference period determining means includes
When the change amount of the communication quality value in a period included between the predetermined period and the present is less than a predetermined amount,
Determining the reference period as a first period;
When the change amount of the communication quality value in the period included between the predetermined period and the present is equal to or greater than the predetermined amount,
Determining the reference period to be a second period shorter than the first period;
A communication device. The communication device according to claim 2,
The first period is equal to the predetermined period;
A communication device. The communication device according to claim 3,
The second period is a period after the time point when the change in the communication quality value is greater than or equal to the predetermined amount, included in the predetermined period.
A communication device. The communication device according to any one of claims 1 to 4,
The modulation scheme determining means includes
Determining the modulation scheme based on an average value of the communication quality values at the present from before the reference period;
A communication device. The communication device according to any one of claims 1 to 5,
The communication quality value is a value obtained based on a signal transmitted from the communication device and received by the communication partner,
The modulation method is a modulation method of a signal transmitted from the communication device to the communication partner.
A communication device. The communication device according to any one of claims 1 to 5,
The communication quality value is a value obtained based on a signal transmitted from the communication partner and received by the communication device,
The modulation method is a modulation method of a signal transmitted from the communication partner to the communication device.
A communication device. Obtaining a communication quality value indicating the quality of communication performed with a communication partner;
Determining a reference period based on the communication quality value in a period included between a predetermined period before and the present time;
Determining a modulation scheme to be applied in the communication based on the communication quality value in a period from before the reference period to the present time;
A modulation method determination method comprising:

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