CN101951305A - Control channel information transfer approach and base station and the terminal of using this method - Google Patents

Abstract

There is a problem that if MIMO is applied for transmission, the number of variable parameters increases, thereby increasing the number of information bits required for the control channel (FIG. 6, III). There is also a problem that if the number of simultaneous multiplexed users is increased in a single frame, the control channel information is increased in proportion to the number of users. In order to solve these problems, an error correction coding process is performed on the control channel information using an adaptive modulation coding scheme; then the error correction coded control channel information is modulated by using a predetermined coding scheme, and then the control channel information is transmitted; and further set as This makes it possible to change the encoding rate in the error correction encoding process according to the propagation state.

Description

Control channel information transmission method and base station and terminal using the method

This application is an invention patent application with the original application number 200580051722-9 (international application number: PCT/JP2005/018117, application date: September 30, 2005, invention name: control channel information transmission method and base station and Terminal) divisional application.

technical field

The present invention relates to a control channel information transmission method and a base station and a terminal using the method, more specifically, to a control channel information transmission method for packet communication that uses a control channel to adaptively control communication parameters, and uses A base station and a terminal of the method.

Background technique

In third generation mobile communication systems, adaptive radio links such as adaptive modulation/demodulation, HARQ (Hybrid Automatic Repeat Request) and scheduling are used to increase the transmission efficiency of data packets.

Such an adaptive radio link is controlled using an individual or common control channel, and each user terminal is informed of the link parameters used in the data channel transmitted substantially simultaneously with the control channel.

For example, in case of an Adaptive Modulation and Coding (AMC) scheme, the control channel conveys the modulation scheme and coding rate of the data channel. In the case of HARQ, the control channel conveys information such as the packet number and the number of retransmissions of the packet to be transmitted on the data channel. In case of scheduling, the control channel conveys information such as user ID.

HSDPA (High Speed Downlink Packet Access) standardized according to 3GPP (Third Generation Partnership Protocol) of the third generation mobile communication system, as described in Non-Patent Document 1, uses The control information transmission shown in Table 1 is performed on the common control channel of the shared control channel of the HS-DSCH.

Table 1

Channelization code group information 7 bits

Modulation scheme information 1 bit

Transmission block size information 6 bits

Mixed ARQ processing information 3 bits

Redundancy and constellation version 3 bits

New data indicator 1 bit

Ue identity 16 bits

Furthermore, according to the above-mentioned HSDPA, when the AMC scheme is applied in FIG. 1 showing the relationship between the radio environment and the transmission speed, in a good propagation state (over a threshold level TH) in a changing radio environment I, by Setting the modulation scheme to 16QAM (Quadrature Amplitude Modulation) performs high-speed data transmission with an increased coding rate.

On the other hand, in a bad propagation state (below the threshold level TH), data transmission is performed at a low speed with a reduced coding rate by setting the modulation scheme to QPSK (Quadrature Phase Shift Keying).

In this way, by using the AMC scheme to change the user's transmission speed, the quality remains unchanged. That is, as shown in FIG. 1 above, according to HSDPA, the modulation scheme and coding rate of the HS-DSCH, and user data can be changed according to the propagation state I. In addition, HS-SCCH, which is control information related to the above-mentioned user data, is also transmitted together with user data (HS-DSCH).

However, at this time, regarding the HS-SCCH, that is, the control information, as shown in FIG. 2 showing the relationship between the radio environment and the amount of information, the encoding rate of the error correction encoding for the control information IV is constant, whereby , the amount of information to be transmitted remains constant regardless of whether the radio environment I is good or bad.

In the case described above, when the radio environment I is in a good state, the quality becomes excessive for the transmitted control information.

Furthermore, in the next-generation mobile communication system, in order to realize high-speed data transmission, multi-carrier transmission and MIMO (Multiple Input Multiple Output) transmission using multiple antennas are employed. In this case, transmission characteristics can be further improved by using radio parameter adaptive control on a subcarrier-by-subcarrier basis and on an individual transmission antenna basis.

When using MIMO as described above, control of whether to apply MIMO is performed according to whether the propagation state I is good or not, as shown in FIG. 3 . That is, in FIG. 3 showing the relationship between whether MIMO is applied and the transmission speed, the transmission speed becomes high when MIMO is applied, and in the opposite case, the transmission speed becomes low.

In addition, the applicant of the present invention has previously proposed an invention in which one control channel format is selected from a plurality of control channel formats each having a different amount of information according to a predetermined state (whether MIMO is applied) in a transmission system employing MIMO , and use the above selected control channel format to transmit the control channel (International Application WO/2006/070466: hereinafter referred to as the previous application for short).

The above-mentioned prior application addresses the assumption that the number of control channel information bits is different depending on whether MIMO is applied or not. As a prerequisite, when MIMO is applied to user data (period III), the number of information bits IV increases, as shown in FIG. 4 , and when MIMO is not applied to user data, the number of information bits IV decreases, as shown in FIG. 5 .

Thus, as shown in FIG. 6 showing the relationship between MIMO application and control channel information amount, in period III of propagation environment I to which MIMO is applied, there is a problem that the number of variable parameters increases , and the number of information bits required for the control channel increases. Furthermore, when the number of simultaneous multiplexed users in a single frame increases, there is a problem that control channel information also increases in proportion to the number of users.

[Non-Patent Document 1]

3GPP TS 25.212V5.9.0(2004-06)

Contents of the invention

The problem to be solved by the present invention

Thus, the present invention focuses on solving the above-mentioned problems in packet-type data transmission to which the AMC (Adaptive Modulation and Coding) scheme is applied by making the coding rate variable for error correction coding of HS-SCCH, ie, control channel information.

means of solving problems

As a first aspect of the present invention to solve the above-mentioned problems, a control channel information transmission method includes the steps of: performing error correction coding on control channel information based on an adaptive modulation and coding scheme; The control channel information is modulated and transmitted; and, the coding rate in the error correction coding is made different according to the propagation state.

Furthermore, as a second aspect of the present invention that solves the above-mentioned problems, the control channel information transmission method includes the steps of: performing error correction coding on the control channel information based on an adaptive modulation and coding scheme using a constant coding rate; According to the scheme, the error-correction coded control channel information is modulated and transmitted; and, before modulation, code extraction or code repetition is performed on the error-correction coded signal according to the propagation state.

In addition, as a third aspect of the present invention that solves the above-mentioned problems, the control channel information transmission system based on an adaptive modulation and coding scheme includes: an error correction coding unit that performs error correction coding on the control channel information at the base station side; and a modulation unit , which modulates the coded output of the error correction coding unit according to a predetermined modulation scheme. Also, it is set such that the coding rate in the error correction coding unit is made to differ according to the propagation state.

Also, in the above aspect, the coding rate of the control channel when MIMO is applied is set higher than that when MIMO is not applied, so that the number of transmission code bits is constant regardless of whether MIMO is applied.

In the above aspect, on the reception side, each error correction decoding unit corresponding to a coding rate that differs according to the propagation state performs error correction decoding of a commonly received signal, and furthermore, determines the likelihood of the error correction decoded signal , and output an error-corrected decoded signal determined to be valid based on the likelihood determination result.

Features of the present invention will become apparent through the embodiments of the present invention described with reference to the accompanying drawings.

Description of drawings

FIG. 1 is a graph showing the relationship between radio environment and transmission speed in AMC control of HS-DSCH of HSDPA which is the prior art.

FIG. 2 is a graph showing the relationship between the radio environment and the amount of information in the HS-SCCH of HSDPA which is the prior art.

FIG. 3 is a graph showing the relationship between radio environment and transmission speed in HS-DSCH to which MIMO is applied in the previous application.

Fig. 4 is a diagram showing an embodiment of a control channel format when MIMO is applied.

Figure 5 is a diagram showing an embodiment of a control channel format when MIMO is not applied.

FIG. 6 is a diagram showing a diagram of a relationship between a radio environment and an information amount in an HS-SCCH when MIMO is applied.

FIG. 7 shows a structural block diagram of a transmission system including a base station 1 and a user terminal 2 to which the present invention is applied.

FIG. 8 is a diagram showing the structure of the control channel generation section 12 corresponding to the invention of the previous application.

FIG. 9 is a diagram showing a first exemplary structure of the control channel generating section 12 according to the present invention.

FIG. 10 is a graph showing the relationship between the application of MIMO and the amount of control channel information when the present invention is applied.

FIG. 11 is a diagram showing another exemplary structure of the control channel generation section 12 according to the present invention.

FIG. 12 is a diagram showing an exemplary structure of a control channel demodulation section in a user terminal according to the present invention.

FIG. 13 is a graph showing a comparison of the effect of the present invention with the case of using the invention of the previous application.

Detailed ways

Hereinafter, embodiments of the present invention are described with reference to the drawings.

FIG. 7 shows a structural block diagram of a transmission system including a base station 1 and a user terminal 2 to which the present invention is applied. Specifically, the present invention is characterized by the structure of the embodiment of the control channel generation unit 12 .

Regarding the downlink control channel transmission from the base station 1 to the user terminal 2, the characteristics of the present invention are described using the embodiment of the previous application to which MIMO is applied. However, the application of the present invention is not limited to the transmission system structure shown in FIG. 7 .

Format selection/designation section 10 in base station 1 selects a control channel format based on information including the number of multiplexing users, transmission/reception functions of user terminals, downlink QoS, and downlink CQI (Channel Quality Indicator).

Here, examples of control channel formats to be selected are as previously shown in FIG. 4 (Table 2) and FIG. 5 (Table 3).

Control format A shown in FIG. 4 includes modulation scheme (antenna 1 )-modulation scheme (antenna 4 ), coding rate, spreading factor, and code set as adaptive control parameters. For example, in modulation scheme (antenna 1 )-modulation scheme (antenna 4 ), four (4) modulation scheme types (QPSK, 8PSK, 16QAM, 64QAM) are set as variable ranges. In the above-mentioned control channel format A shown in Table 2, the type and variable range of adaptation parameters are wide, for example, at the time of MIMO transmission, the modulation scheme can be changed antenna by antenna.

Meanwhile, the control format B shown in FIG. 5 includes a modulation scheme (common to antennas), a coding rate, a spreading factor, and a code set as adaptive control parameters. For example, in the modulation scheme (common), two modulation scheme types (QPSK, 16QAM) are set as variable ranges. In the above-mentioned control channel format B shown in Table 3, compared with control channel format A, types and variable ranges of adaptive control parameters are limited, and the number of bits is approximately 1/2 of control channel format A.

Referring back to FIG. 7 , information representing specification of the control channel format selected in format selection/designation section 10 is notified from signaling generation section 11 to user terminal 2 via selector 15 and transmitter 16 as signaling information. Furthermore, the format specifying information is notified to the control channel generation unit 12 and the data channel generation unit 13 .

The control channel generating section 12 is a characteristic part of the present invention, and has a different structure and function corresponding to an embodiment described later, but as a basic structure, the structure includes an error correction coding unit and a modulation unit.

The control channel and data channel generated in the control channel generation unit 12 and the data channel generation unit 13 are multiplexed based on the format designation information in the multiplexing unit 14, and thereafter, the control channel and the data channel are transmitted through the downlink by the transmitter 16. sent to the user terminal 2.

The signaling demodulation section 22 in the user terminal 2 demodulates the signaling information (format specifying information) notified from the base station 1 through the receiver 20, and notifies the control channel demodulation section 23 of the downlink control channel format . The control channel demodulation unit 23 demodulates the control channel based on the downlink control channel format notified from the signaling demodulation unit 22 . The control channel demodulation unit 23 notifies the data channel demodulation unit 21 of the downlink adaptive control parameters demodulated from the control channel.

The data channel demodulation unit 21 demodulates the data channel using the adaptive control parameters notified from the control channel demodulation unit 23 .

The propagation channel measurement unit 24 in the user terminal 2 measures a downlink CQI for selecting a downlink control channel format. The downlink CQI is transmitted to the base station 1 together with the uplink QoS and the transmission/reception function of the user terminal 2 through the uplink control channel from the user terminal 2 to the base station 1 .

Next, uplink control channel transmission from the user terminal 2 to the base station 1 will be described.

Similar to the downlink control format, the uplink control channel format is selected in the format selection/designation section 10 of the base station 1 . In order to select an uplink control channel format, information sets including the number of multiplexed users, transmission/reception functions of user terminals, uplink QoS, uplink CQI (Channel Quality Indicator) and the like are used.

The selected uplink control format is notified from the signaling generator 11 to the user terminal 2 via the selector 15 and the transmitter 16 as signaling information. The signaling demodulation unit 22 demodulates the signaling information notified from the base station 1, specifies the designation (multiplexing method) of the control channel and the data channel on the uplink, and notifies the above-mentioned format designation information to the control channel generation Section 25 and data channel generation section 27.

In the base station 1, the uplink control channel demodulation section 18 for uplink is notified of the uplink control channel format selected by the format selection/designation section 10 .

The control channel demodulation unit 18 demodulates the control channel based on the uplink control channel format notified from the format selection/designation unit 10 . The control channel demodulation unit 18 notifies the data channel demodulation unit 19 of the demodulated uplink adaptive control parameters.

The data channel demodulation unit 19 executes demodulation processing on the data channel using the adaptive control parameters notified from the control channel demodulation unit 18 . The uplink CQI for selecting the format of the uplink control channel is measured by the channel measurement unit 17 in the base station 1 .

In addition, the channel measurement unit 17 notifies the format selection/designation unit 10 of the measured uplink CQI. Also, the uplink QoS, downlink CQI, and transmission/reception function of the user terminal 2 transmitted to the base station 1 through the uplink control channel from the user terminal 2 to the base station 1 are transmitted to the format selection/designation section 10 .

Next, in FIG. 7 , an exemplary structure of the control channel generation section 12 constituting a feature of the present invention will be described. Here, in the previous application, a case where MIMO is applied has been assumed, in which the number of control channel information bits differs according to whether MIMO is applied, as shown in FIGS. 4 and 5 .

That is, from a plurality of control channel formats, one control channel format is selected and used such that the number of control channel information sets is large when MIMO is applied to user data (refer to FIG. 4 ), while the control channel The number of information sets is small (Fig. 5).

In the above case, the structure of the control channel generating section 12 is as shown in FIG. 8 .

An error correction encoding unit 120 and a modulation unit 121 are provided. Error correction encoding is performed in the error correction encoding unit 120, and correspondingly, error correction decoding is performed in the control channel demodulation unit 23 on the user terminal 2 side.

Now, let the encoding rate R be R=0.241, where R is the ratio of the number of code information bits to be transmitted to the number of transmitted code bits obtained by error correction encoding. When MIMO is not applied in FIG. 8, the number of code information bits in a frame to be transmitted is 68, and the number of transmission code bits becomes 282=(68×1/0.241) bits.

Meanwhile, when MIMO is applied, if the number of code information bits in a frame to be transmitted is 141, the number of transmission code bits becomes 585=(141×1/0.241) bits.

In this way, since the coding rate is fixed, there is a problem that the number of transmission code bits becomes large when MIMO is applied, as shown in FIG. 6 .

Accordingly, the object of the present invention is to solve the above-mentioned problems.

FIG. 9 is a diagram showing a first exemplary structure of the control channel generating section 12 according to the present invention. Similar to the structure shown in FIG. 8 , the control channel generation section 12 includes an error correction encoding unit 120 and a modulation unit 121 .

A feature different from the structure shown in FIG. 8 is that the encoding rate in the error correction encoding unit 120 is variable.

The case of a large coding rate is weaker with respect to propagation path errors, while the case of a small coding rate is stronger with respect to propagation path errors. Meanwhile, MIMO is applied when propagation errors rarely exist, and MIMO is not applied when propagation errors occur frequently.

Therefore, according to the present invention, when MIMO is applied to user data, the coding rate of the error correction coding unit that generates the control channel increases. In contrast, when MIMO is not applied to user data, the coding rate of the error correction coding unit that generates the control channel decreases.

As one embodiment, when MIMO is applied to user data, the coding rate of the error correction coding unit 120 in the control channel generation section 12 is set to 0.5.

Thus, the number of transmission code bits is 282 (=141÷0.5), and when MIMO is not applied to user data, as in the exemplary case shown in FIG. 8, the coding rate in the error correction coding unit 120 is set to 0.24, And thus 282 (=141÷0.5) bits are transmitted.

Thus, no matter whether MIMO is applied or not, the number of transmitted codes is the same, and constant control information quality can be obtained without wasting radio resources.

FIG. 10 is a graph showing the relationship between the application of MIMO and the amount of control channel information when the present invention is applied. Compared with FIG. 6, even if MIMO is applied, the number of transmission code bits of error correction coding can be made constant. Therefore, waste of resources can be prevented.

FIG. 11 is a diagram showing another exemplary structure of the control channel generation section 12 according to the present invention. In the present embodiment, there is a feature that a unit 122 for selectively applying a puncture function or a repetition function is provided between the error correction encoding unit 120 and the modulation unit 121 .

That is, according to the present embodiment, the coding rate of error correction coding section 120 is made constant regardless of whether MIMO is applied or not. Meanwhile, it is set as follows: By providing a unit 122 having a puncturing function or a repeating function at the output of the error correction encoding unit 120, the encoding rate is changed in an equivalent manner.

In this way, the coding rate is made variable at the input of modulation section 121, which has the same meaning as the structure of control channel generator 12 shown in FIG. 9 .

Now, in the case where the puncturing function is provided, by the puncturing function, when MIMO is applied, the unit 122 performs decimation processing of the output data of the error correction encoding unit 120 at certain time intervals. When MIMO is not applied, the output data of the error correction encoding unit 120 is passed through unchanged. Thus, regardless of whether MIMO is applied or not, when the output of error correction coding section 120 is input to modulation section 121, the bit count is the same.

Furthermore, when the repetition function is provided, by the repetition function, the unit 122 repeatedly outputs the same bit of the output data of the error correction encoding unit 120 when MIMO is not applied. Also in this case, the number of transmission bits when MIMO is not applied can be made substantially equal to the number of transmission bits when MIMO is applied.

Figure 12 shows another embodiment of the present invention. In the transmission system shown in FIG. 7 , as a function of the signaling generating section 11 in the base station 1 , whether MIMO is applied and the format in the control channel generating section 12 is notified. The embodiment shown in FIG. 12 makes the above-mentioned functions of the signaling generating section 11 unnecessary.

That is, on the receiving side that is the user terminal 2, reception is performed using two control channel formats corresponding to cases where MIMO is applied and when MIMO is not applied. Then, whichever format appears to be correct is detected from the received data. Thus, the base station 1 , that is, the transmitting side, can notify the receiving end whether to apply MIMO without using information bit resources to notify whether to apply MIMO.

In the control channel demodulation section 23 shown in FIG. 12 , on the output side of the demodulator 230 that demodulates the signal transmitted from the base station 1 side without performing signaling demodulation, two error correction decoding Units 231a and 231b respectively correspond to the above two control channel formats.

The first error correction decoding unit 231a can obtain a correct output when performing error correction decoding on a frame signal with 68 bits when MIMO is not applied. For this reason, the error correction decoding unit 231a performs error correction decoding based on the assumed encoding rate=0.24.

At the same time, the second error correction decoding unit 231b can obtain a correct output when performing error correction decoding on the frame signal with 141 bits when MIMO is applied. For this reason, error correction decoding is performed based on an assumed encoding rate=0.5.

The reliability determination and selection unit 232 determines which decoding result appears to be correct based on the output of the first error correction decoding unit 231a and the second error correction decoding unit 231b, and selects either side of the error correction decoding unit 231a, 231b based on the above results Output.

Thereby, it is possible to save information bit resources for notifying whether MIMO is applied.

FIG. 13 is a graph showing a comparison of the effect of the present invention with the case of using the invention of the previous application.

FIG. 13A shows the transmission power ratio from a base station using HSDPA. The remaining power not shown in Figure 13A corresponds to the power assigned to the traffic channel.

Figure 13B shows the available power in traffic channels obtained from Figure 13A based on the number of channels in the HS-SCCH. As previously described, according to the invention in the previous application, the coding rate of the HS-SCCH is constant even if the amount of information is large. Depending on whether MIMO is applied, the available power of the traffic channel becomes different (refer to III in FIG. 13B ). In contrast, according to the present invention, the aforementioned power is constant (cf. IV in FIG. 13B ).

For example, in the case of two traffic channels (shown by arrows in FIG. 13B ), in terms of power, the effect of the present invention is 1.5 times greater than that of the invention in the previous application.

Industrial applicability

As already described with reference to the drawings, in the present invention, by making the coding rate of the error correction code changeable according to the control channel mode, the transmission quality can be kept constant regardless of whether the propagation state is good or bad, and furthermore, even if MIMO is applied , which also prevents excess quality of transmission of control information bits.

Claims (12)

1. A method of transmitting control channel information for adaptive coding and modulation, the method comprising the steps of: performing error correction encoding on the control channel information at a predetermined encoding rate; modulate and transmit the error correction coded control channel information according to a predetermined modulation scheme; and Before the modulation, code decimation or code repetition is also performed on the error correction coded signal according to whether multiple-input multiple-output is applied. 2. The method according to claim 1, Wherein, the amount of code extraction of the control channel information is set to be greater than the amount of code extraction when MIMO is not applied when MIMO is applied, so that the number of bits of the transmission code becomes constant, regardless of whether MIMO is applied Input and output are irrelevant. 3. according to the method for claim 1 or 2, this method also comprises the following steps: receiving and demodulating said control channel information transmitted from a transmitting site according to said predetermined modulation scheme; and The demodulated control channel information is error-corrected decoded corresponding to a coding rate based on said code decimation or said code repetition, respectively, depending on whether multiple-input multiple-output is applied. 4. The method according to claim 1 or 2, further comprising: error-correcting decoding of the commonly received signal by means of respective error-correcting decoding units corresponding to encoding rates based on said code extraction or said code repetition, respectively, according to whether multiple-input multiple-output is applied; determining the likelihood of these error correction decoded signals; and Based on this likelihood determination result, an error correction decoded signal determined to be valid is output. 5. A control channel information transmission system for transmitting control channel information for adaptive coding and modulation, the control channel information transmission system comprising: on the base station side, an error correction encoding unit configured to perform error correction encoding on the control channel information at a predetermined encoding rate; a modulation unit configured to modulate the coded output of the error correction coding unit according to a predetermined modulation scheme, and A unit configured to perform code decimation or code repetition of an error-correcting encoded signal on the output of the error-correcting encoding unit depending on whether multiple-input multiple-output is applied. 6. The control channel information transmission system according to claim 5, Wherein, the unit configured to perform code extraction or code repetition of the error correction coded signal sets the amount of code extraction of the control channel information when multiple-input multiple-output is applied to be greater than that when multiple-input multiple-output is not applied so that the number of bits of the transmission code becomes constant regardless of whether MIMO is applied or not. 7. The control channel information transmission system according to claim 5, the control channel information transmission system further comprising: at the receiving site, a unit configured to receive and demodulate said control channel information transmitted from a transmitting site according to said predetermined modulation scheme, and further configured to extract Or the code repeats the code rates corresponding to the error correction decoding. 8. The control channel information transmission system according to claim 5 or 6, the control channel information transmission system further comprising: at the receiving site, a plurality of error correction decoding units, which are respectively configured to perform error correction decoding on a commonly received signal corresponding to a coding rate respectively based on the code decimation or the code repetition according to whether multiple-input multiple-output is applied; determining the likelihood of these error-corrected decoded signals; and An error correction decoded signal determined to be valid is output based on the likelihood determination result. 9. A base station in a control channel information transmission system for transmitting control channel information for adaptive coding and modulation, the base station comprising: an error correction coding unit configured to perform error correction coding on the control channel information at a predetermined coding rate; a modulation unit configured to modulate the error correction encoded control channel information obtained in the error correction encoding unit using a predetermined modulation scheme; and A unit configured to perform code decimation or code repetition on the output of the error correction coding unit before the modulation of the modulation unit according to whether multiple-input multiple-output is applied. 10. The base station according to claim 9 , wherein said unit arranged to perform code decimation or code repetition sets the amount of code decimation when multiple-input multiple-output is applied to be greater than the amount of code decimation when multiple-input multiple-output is not applied amount so that the number of bits of the transfer code becomes constant regardless of whether MIMO is applied or not. 11. A user terminal for receiving control channel information corresponding to the base station according to claim 9 or 10, the user terminal comprising: A unit configured to receive and demodulate said control channel information transmitted from a transmission site according to said predetermined modulation scheme, and this unit is also configured to, according to whether multiple-input multiple-output is applied, respectively and said code The code rate corresponding to the decimation or code repetition performs error correction decoding on the demodulated control channel information. 12. A user terminal for receiving control channel information corresponding to the base station according to claim 9 or 10, the user terminal comprising: a plurality of error correction decoding units, which are respectively configured to perform error correction decoding on a commonly received signal corresponding to a coding rate respectively based on the code decimation or the code repetition according to whether multiple-input multiple-output is applied; and An output unit configured to determine the likelihood of the error-correction decoded signals and output the error-correction decoded signal determined to be valid based on the likelihood determination result.

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