JP2009044768A - Wireless receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the number of receiver antennas of a wireless receiver used for a multi-input/multi-output (MIMO) radio system smaller than that of a conventional system. <P>SOLUTION: In the MIMO radio communication system comprising a wireless transmitter for transmitting a plurality of transmission signal sequences from a plurality of antennas by radio and the wireless receiver for separating the signals received by a plurality of antennas and restoring the transmission signal sequences, there is provided the radio communication system wherein the wireless transmitter transmits the same signal several times and time diversity transmission is performed. The wireless receiver performs signal separation processing over a plurality of steps and further estimates one transmission signal on the basis of one received signal and a plurality of transmission signals obtained as the estimated result in the preceding step. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention generally belongs to the technical field of wireless communication, and particularly relates to a multi-input multi-output (MIMO) wireless communication system and a wireless transmitter and a wireless receiver used therein.

  In MIMO wireless communication, different transmission signal sequences are transmitted from the plurality of antennas at the same time and at the same frequency. On the receiving side, they are received by a plurality of antennas, and signal transmission is performed to restore the transmission signal sequence. By using a plurality of antennas for transmission and reception, it becomes possible to use space effectively and increase transmission capacity. For example, the signal transmission rate can be increased by several times the number of transmission antennas. The MIMO communication technology is disclosed in Non-Patent Document 1, for example.

  For signal separation for obtaining a transmission signal from a received signal, for example, a ZF (Zero Forcing) method, an MMSE (Minimum Mean Square Error) method, an MLD (Maximum Likelihood Decision) method, or the like can be used. For example, Non-Patent Document 2 discloses a method of detecting using MLD. The detection method of Non-Patent Document 2 is generally a technique using MLD, which estimates a channel response value or a channel impulse response value (CIR: channel impulse response value) using a pilot signal and receives all of them. Are generated, the square Euclidean distance between the actual received signal and the generated signal is obtained, and the signal point at which the signal point is minimized is obtained, thereby estimating the transmission signal.

For example, it is assumed that signals s1 and s2 are transmitted from two transmission antennas, received as received signals r1 and r2, and the modulation method is QPSK. In this case, there are 16 combinations of signals to be transmitted. For each of the 16 patterns, the square distance (error) between the actual received signals r1 = h11s1 + h12s2 and r2 = h21s1 + h22s2 is obtained, and a combination of signals (s1, s2) that minimizes the error is estimated as a transmission signal. It is.
G. J. et al. Foschini, Jr. , "Layered space-time architecture for wireless communication in a fading environment when multi-element antennas", Bell Labs Tech. J. et al. , Pp. 41-59, Autumn 1996 A. V. Zelst, R.A. V. Nee, and G.C. A. Awater, “Space Division Multiplexing (SDM) for OFDM systems,” in Proc. VTC spring '00, vol. 2, pp. 1070-1074, May 2000

  As described above, in MIMO wireless communication, a transmission signal sequence is restored by signal separation of signals obtained from a plurality of antennas. Therefore, the wireless receiver used for this communication method needs to include a plurality of antennas. For example, a device having a wireless communication function such as a portable computer or a personal digital assistant (PDA) can be provided with a sufficient number of such antennas.

  However, it is difficult for a small-sized mobile terminal such as a mobile phone to have many receiving antennas in a radio receiver. For this reason, the problem that the applicability (use) of a MIMO system will be restrict | limited.

  On the other hand, in the MIMO scheme, (separate) signals simultaneously transmitted from a plurality of transmission antennas at the same frequency are received by a plurality of antennas, and an attempt is made to detect based on the plurality of reception signals. Therefore, if the number of reception antennas provided in the wireless receiver is small, reception characteristics may be deteriorated due to interference caused by the same frequency, and the accuracy of signal separation may deteriorate.

  The present invention has been made to cope with such a problem, and the subject thereof is to be used in a MIMO wireless communication system capable of reducing the number of reception antennas as compared with the prior art and the wireless communication system thereof. It is to provide a wireless transmitter and a wireless receiver.

The wireless communication system used in the present invention is:
A wireless transmitter that wirelessly transmits a plurality of transmission signals from a plurality of antennas;
A radio receiver that separates signals received by a plurality of antennas and restores the transmission signal;
In a multiple input multiple output (MIMO) wireless communication system comprising:
In the wireless communication system, the wireless transmitter transmits the same signal a plurality of times and performs time diversity transmission.

  According to the present invention, it is possible to reduce the number of receiving antennas compared to the conventional art, and it is possible to expand the use of MIMO communication.

  According to one embodiment of the present invention, a wireless transmitter transmits the same signal a plurality of times (K times), and a signal separation is performed based on a signal received by the wireless receiver a plurality of times, thereby obtaining a time diversity effect. . For this reason, even if the number of receiving antennas is reduced, it is possible to obtain reception characteristics comparable to those of the conventional art.

  According to one aspect of the present invention, the transmission interval is appropriately adjusted according to the propagation path environment. For this reason, it is possible to avoid the disadvantage that the transmission time is unnecessarily prolonged.

  According to one embodiment of the present invention, when a signal is transmitted by a certain antenna and then retransmitted, the signal is retransmitted by an antenna different from the antenna. Since the transmission path between the previous transmission and the retransmission is different, the possibility that the retransmitted signal is appropriately received can be increased. Furthermore, it is possible to further improve reception quality by performing retransmission using an antenna used before retransmission and an antenna different from the antenna.

  According to one aspect of the present invention, for example, when the error detection result is good, retransmission of the same signal is stopped. For this reason, excessive retransmission can be avoided.

A MIMO wireless receiver according to an aspect of the present invention is provided.
First estimation means for estimating each of the transmission signals from a plurality of reception signals received by a plurality of antennas;
A plurality of subtracting means, wherein each subtracting means is obtained by multiplying one received signal included in the plurality of received signals and at least one transmission signal estimated by the first estimating means by a channel impulse response value. A plurality of subtraction means for obtaining the difference between
And second estimation means for estimating transmission signals transmitted from a plurality of antennas based on a plurality of differences obtained by a plurality of subtraction means.

  Since the transmission signal is estimated repeatedly, the transmission signal can be estimated with high accuracy.

  According to one aspect of the present invention, there is further provided error detection means for detecting errors of a plurality of transmission signals estimated by the first estimation means. According to an aspect of the present invention, there is further provided an error correction unit that corrects each of the plurality of transmission signal errors estimated by the first estimation unit and outputs a likelihood based on the error correction result. Since the subsequent estimation is performed based on the reliable transmission signal, it is possible to further improve the accuracy of the transmission signal.

  According to one aspect of the present invention, a plurality of signal blocks included in at least one received signal are transmitted in the order rearranged by the interleaver.

  FIG. 1 is a conceptual diagram of a MIMO wireless communication system 100 according to an embodiment of the present invention. The wireless communication system 100 includes a wireless transmitter 102 having M antennas and a wireless receiver 104 having N ′ antennas. M is an appropriately selected integer of 2 or more and N ′ is 1 or more. Here, N ′ is a value defined by N ′ = N / K, K is the number of retransmissions of the same signal according to the present invention, and N is when the present invention is not used (when K = 1). The number of receiving antennas required. The number of retransmissions K will be described later. For convenience of explanation, 102 is a wireless transmitter and 104 is a wireless receiver. However, any of them may actually have a transmission / reception function.

  Radio transmitter 102 transmits a transmission signal sequence from each of M antennas. In general, the M transmission signal sequences are different from each other, but as described later, in one embodiment, they may be the same signal sequence. Unlike the prior art, the wireless transmitter 102 includes a diversity transmission control unit 106. Diversity transmission control section 106 performs control for performing time diversity. In particular, the diversity transmission control unit 106 performs operations such as adjusting the transmission interval T of the same signal repeatedly transmitted and selecting an antenna that transmits the same signal.

  The radio receiver 104 receives signals through N ′ antennas and performs signal separation to restore a transmission signal sequence. Unlike the prior art, the wireless receiver 104 includes a diversity reception control unit 108. Diversity reception control section 108 performs control for performing time diversity reception. In particular, the diversity reception control unit 108 performs operations such as determining the number of receptions of a signal received repeatedly and creating and notifying a transmission stop signal according to an error detection result.

  FIG. 2 is a diagram illustrating a state of wireless transmission according to the present embodiment. Each shaded block indicates the same signal content. For example, when the wireless packets (or transmission signal sequences) 1 to M are transmitted from the antennas 1 to M of the wireless transmitter at the first transmission, respectively, at the time of k (1 ≦ k <K) transmission and K transmission Also, wireless packets 1 to M are transmitted from antennas 1 to M of the wireless transmitter, respectively. Here, K is 2 or more.

  In this embodiment, unlike the conventional MIMO wireless communication system, the same signal is transmitted a plurality of times (K times), and time diversity is performed. By performing time diversity, the transmission signal sequence is repeatedly transmitted K times, so that the signal sequence is received K times more on the receiving side. Therefore, even if the number of antennas on the reception side is reduced to 1 / K, the reception quality on the reception side is maintained constant, and the reception characteristics are not impaired. In the present embodiment, information that has been received once by N antennas is received by (N ′ = N / K) antennas K times in this embodiment.

  It is desirable that the transmission interval T at which the transmission signal sequence is repeatedly transmitted is set to be sufficiently separated so that the correlation becomes small so that the signal separation on the receiving side can be accurately performed. For example, it is possible to reduce such correlation by setting a sufficiently long transmission interval. However, the longer the transmission interval, the longer the delay time. Therefore, it is desirable that the transmission interval T is appropriately adjusted (shortened) according to the propagation path environment. For example, it is advantageous to adjust the length of the transmission interval according to the magnitude of fading time fluctuation. It is possible to adjust the transmission interval by decreasing the transmission interval when fading time variation is large (when the maximum Doppler frequency is large), and by increasing the transmission interval when fading time variation is small. Such adjustment of the transmission interval T is performed by, for example, feeding back transmission path parameters (received signal-to-noise power ratio, maximum Doppler frequency, number of received paths, delay spread, etc.) measured on the receiving side to the transmitting side. It is possible to do. Alternatively, it is also possible to determine the transmission interval T on the receiving side based on the transmission path parameter measured on the receiving side and notify the transmitting side of it.

  FIG. 3 is a diagram illustrating signal transmission according to an embodiment of the present invention. In the above embodiment, instead of reducing the number of antennas on the receiving side by (1 / K) times, the same signal is repeatedly transmitted, so the number of repetitions is in principle K. For this reason, as shown in FIG. 3A, after the same signal is received K times on the receiving side, signal separation and other processes for restoring the transmission signal sequence are started.

  However, the present invention is not limited to such examples. For example, as shown in FIG. 3B, signal separation processing or the like can be performed each time the same signal is received while performing error detection. When no error is detected (or when the error rate becomes a predetermined value or less), it is possible to save communication resources and improve transmission efficiency by stopping subsequent repeated transmission of the same signal. It becomes possible. In the example shown in FIG. 3B, it is detected that there is no error when the wireless receiver receives the signal transmitted at the kth time (1 ≦ k <K), and the subsequent transmission (from the k + 1th time) The wireless receiver notifies the wireless transmitter that the transmission of the same signal up to the Kth time should be stopped. This notification can be made through an appropriate control channel. Upon receiving the notification, the wireless transmitter stops the subsequent repetitive transmission, and can transmit a new transmission signal sequence to the wireless receiver, or transmit to another wireless receiver.

  FIG. 4 is a conceptual diagram for explaining another embodiment. In this embodiment, in addition to time diversity being performed in MIMO wireless communication, an automatic repeat request (ARQ) process is performed. In a communication system that performs ARQ, a retransmission request signal is notified to the transmission side so that a packet in which an error is detected on the reception side is retransmitted. The transmitting side retransmits the designated packet in response to this signal. In this way, the technique using ARQ enables error-free transmission by performing retransmission in response to a retransmission request signal. In this embodiment, in addition to the same signal being retransmitted at an appropriate transmission interval T, when the wireless transmitter receives an automatic retransmission request from the wireless receiver, the packet specified by the automatic retransmission request signal Will be resent.

  As shown in the upper side of FIG. 4, it is assumed that the wireless transmitter wirelessly transmits the first packet from the first antenna 402 and the second packet from the second antenna 404. Then, it is assumed that the radio receiver that has received the error detects no error for the first packet and detects an error for the second packet. The wireless receiver transmits an automatic retransmission request signal so as to retransmit the second packet to the wireless transmitter. In response to the automatic retransmission request signal, the wireless transmitter retransmits the second packet. In this case, the wireless transmitter can retransmit the second packet from the second antenna 404 as in the initial transmission. However, if the conditions of the radio propagation path at the time of initial transmission and retransmission are the same, there is a high possibility that an error will be detected again in the retransmitted second packet. Therefore, as shown in FIG. 5 (lower side of FIG. 5), it is advantageous to transmit the second packet from the first antenna 402 at the time of retransmission. Since the second packet passes through a radio propagation path different from that at the time of initial transmission, there is a high possibility that the second packet is received well. Furthermore, as shown in FIG. 6 (lower side of FIG. 6), it is also advantageous to copy a plurality of packets indicated in the automatic retransmission request signal and transmit them from a plurality of antennas. In the illustrated example, it is possible to transmit the second packet reliably by transmitting the second packet not only from the first antenna 402 but also from the second antenna 404. In addition to transmitting the same packet, it is also possible to apply space-time channel coding (Space Time Coding). Furthermore, the above methods can be adaptively switched. For example, using the reception quality (reception SIR, reliability obtained from the channel decoder, etc.), if the quality is poor, it is transmitted from two antennas. By performing control such as transmission, throughput can be improved.

  For simplicity of explanation, two antennas have been described as an example, but it is naturally possible to use more antennas. In response to the automatic retransmission request signal or when retransmitting the same signal by time diversity, the transmission diversity control unit 106 can appropriately set which antenna among the plurality of antennas to transmit the signal.

  As described above, when the number of reception antennas decreases, there is a risk that the reception characteristics are degraded. In the above embodiment, the transmission signal is repeatedly transmitted to cope with the deterioration of the reception signal. In the embodiment described below, an attempt is made to cope with degradation of reception characteristics by improving the accuracy of signal separation. This embodiment can be used in place of or in conjunction with the first embodiment described above.

  FIG. 7 is a conceptual diagram of a MIMO wireless communication system according to an embodiment of the present invention. The system includes a wireless transmitter 702 having M antennas and a wireless receiver 704 having N antennas. The wireless receiver 704 includes a first signal separation processing unit 706, N subtracters 708_1 to 708_N, and K signal separation processing units 706_1, 706_2,... 706_K.

  The wireless transmitter 702 receives M signal sequences and transmits them as transmission signals s1, s2,..., SM from the first antenna, the second antenna,. .

  The wireless receiver 704 receives signals including transmission signals s1, s2,..., SM as reception signals r1, r2,. In this case, channel impulse response values (CIR) h11,..., HNM between the antennas of the wireless transmitter 702 and the wireless receiver 704 are estimated in advance using pilot signals. . The radio receiver 704 generally functions to output (separate) M transmission signals separately based on reception signals r1, r2,..., RN received by N antennas.

  The first signal separation processing unit 706_1 receives the reception signals r1, r2,..., RN received by the N antennas, and the estimated transmission signals s1 ′, s2 ′,. Is estimated. The estimation method is not limited to a specific method, and various methods such as a ZF method, an MMSE method, and an MLD method can be used. In this embodiment, the MLD method is used. The subtracters 708_1 to 708_N obtain the differences between the received signals r1, r2,..., RN and the replica sets 1,.

  Similarly, a subtractor and a signal separation processing unit are repeatedly provided, and the wireless receiver 704 is provided with a total of K signal separation processing units and (K−1) × N subtractors. .

  Next, signal separation processing according to the present embodiment will be described.

  Here, the signals transmitted from the M transmitting antennas estimated by the i-th (i = 1 to K−1) signal processing unit 706 — i are denoted as s1 (i), s2 (i),. Let sM (i). A channel impulse response value between the β-th (β = 1 to M) transmitting antenna and the α-th (α = 1 to N) receiving antenna is assumed to be hαβ.

  In the (i + 1) th signal processing unit 706_i + 1, M transmission signals s1 (i), s2 (i),..., sM () estimated by the i-th (i = 1 to K−1) signal processing unit 706_i. From i), M transmission signals s1 (i + 1), s2 (i + 1),..., sM (i + 1) are estimated again. In order to estimate the first transmission signal s1 (i + 1), the following processing is performed.

  A component related to a transmission signal other than the first transmission signal s1 (i) (this component is referred to as a “replica set”) is removed from the reception signal r1 received by the first reception antenna. For example, if N = 2 and M = 3, then r1 = h11s1 (i) + h12s2 (i) + h13s3 (i). Components (replica sets) related to transmission signals other than s1 (i) are h12s2 (i)) + h13s3 (i). The individual terms h12s2 (i) and h13s3 (i) in the replica set are simply called “replicas”. By subtracting this replica set from the reception signal r1 of the first antenna, a signal component h11s1 (i) relating to the first transmission signal is obtained.

  Next, signal components related to the first transmission signal s1 (i) are removed from the reception signal r2 received by the second reception antenna by removing components related to the transmission signal other than the first transmission signal s1 (i). Ask for. Similarly, by removing components related to the transmission signal other than the first transmission signal s1 (i) from the reception signal rN received by the Nth reception antenna, the first transmission signal s1 (i) is related. Find the signal component. In the case of N = M = 2, the signal component h21s1 (i) relating to the first transmission signal is obtained by subtracting the replica (h22s2 (i)) from the reception signal r2.

  The first transmission signal s1 (i + 1) can be obtained based on the N signal components related to the first transmission signal s1 (i) thus obtained and the known channel impulse response value hαβ. is there. When N = M = 2, s1 (i + 1) is estimated from the signal component h11s1 (i) obtained from the received signal r1 and the signal component h21s1 (i) obtained from the received signal r2.

  By repeating the same procedure, updated estimated values s2 (i + 1),..., SM (i + 1) of the second and subsequent transmission signals are obtained.

  Note that the replica set in the case of N = M = 2 is only represented by one term, but the replica set in the case where there are more signal components is, in principle, M−1 transmission signals. Expressed by linear combination, the coupling coefficient is a channel impulse response value.

  According to this embodiment, one transmission signal (for example, s1 (i + 1)) is obtained based on the estimated values s1 (i), s2 (i),..., SM (i) of M transmission signals. Estimated with high accuracy. By repeating such processing K times, signal separation can be performed with high accuracy.

  FIG. 8 is a diagram showing how a replica set is generated in one embodiment of the present invention. In this example, a plurality of error detection decoding units 802_1 to 802_M and a replica generation unit 804 connected to them and outputting a replica set or replica are provided.

  Error detection decoding sections 802_1 to 802_M detect errors in a plurality of (M) transmission signals estimated by signal separation processing section 706, respectively, and provide the transmission signals together with the detection results to replica generation section 804.

  In the above example, the replica set is represented by a linear combination of M−1 transmission signals in principle, and the coupling coefficient is a channel impulse response value. However, using the transmission signal in which an error is detected as it is to execute the calculation is not preferable from the viewpoint of achieving high accuracy. Therefore, when the replica generation unit 804 generates a replica set, the replica set is generated by excluding the estimated value of the transmission signal in which an error is detected. In the illustrated example, since an error is detected in the second transmission signal s2, the replica generation unit 804 creates a replica set that does not include the second transmission signal s2. According to this method, since the signal separation calculation is performed using only the transmission signal in which no error is detected, it is possible to increase the estimation accuracy of the transmission signal.

  FIG. 9 is a diagram showing how a replica set is generated in one embodiment of the present invention. In this example, a plurality of multiplication units 902_1 to 902_M connected to the signal separation processing unit 706 and a replica generation unit 904 are provided.

  Each of the plurality of multipliers 902_1 to 902_M gives certain weights or weights α1 to αN to the transmission signal estimated by the signal separation processing unit 706, respectively. These weights αk (0 ≦ αk ≦ 1) are determined based on the likelihood (likelihood) of the transmission signals s1 to sM. The likelihood can be obtained by various methods. For example, a method obtained directly from a received signal, a method obtained in the course of decoding processing of error correction coding, or the like can be used.

  The replica generation unit 904 calculates a replica set based on the weighted transmission signals s1 to sM.

  In this example, when creating a replica set, the transmission signals s1 to sM are not used as they are, but transmission signals weighted by likelihood are used. In the method described with reference to FIG. 8, eliminating a transmission signal in which an error is detected corresponds to setting a weight for the transmission signal to 0 in the example of FIG. 9. According to this example, it is possible to create a replica set in consideration of the probability of the transmission signal, and it is possible to improve the estimation accuracy of the transmission signal.

  FIG. 10 is a diagram illustrating a state in which an interleaved signal is transmitted in an embodiment of the present invention. In this example, the first transmission signal (first packet) s (1) is divided into n blocks and transmitted in order, and the second transmission signal (second packet) s (2) is also divided into n blocks. Although divided, they are transmitted in a different order. Similarly, the Mth transmission signal (Mth packet) s (M) is also divided into n blocks and transmitted in a different order. In this example, it is possible to improve the reliability of communication by rearranging the time order of transmitting transmission signals.

  Hereinafter, the means taught by the present invention will be listed as an example.

(Section 1)
A wireless transmitter that wirelessly transmits a plurality of transmission signals from a plurality of antennas;
A radio receiver that separates signals received by a plurality of antennas and restores the transmission signal;
In a multiple input multiple output (MIMO) wireless communication system comprising:
The wireless communication system, wherein the wireless transmitter transmits the same signal a plurality of times and performs time diversity transmission.

(Section 2)
The wireless communication system according to claim 1, wherein the wireless transmitter has means for adjusting a transmission interval for transmitting the same signal a plurality of times depending on a temporal variation in fading.

(Section 3)
The wireless communication according to claim 1, wherein the wireless transmitter retransmits the signal through one or more antennas different from the one or more antennas after wirelessly transmitting a signal through the one or more antennas. system.

(Section 4)
The wireless transmitter retransmits the signal through one or more antennas and one or more antennas different from the one or more antennas after wirelessly transmitting a signal through the one or more antennas. A wireless communication system according to item 1.

(Section 5)
2. The radio according to claim 1, wherein the radio receiver has means for measuring the number of receptions of the same signal, and performs signal separation in response to receiving the signal a predetermined number of times. Communications system.

(Section 6)
2. The wireless communication system according to claim 1, wherein the wireless receiver has means for notifying the wireless transmitter that transmission of the same signal should be stopped depending on an error detection result.

(Section 7)
A multi-input multiple-output (MIMO) wireless transmitter that wirelessly transmits a plurality of transmission signals from a plurality of antennas includes a transmission control unit that transmits the same signal a plurality of times and performs time diversity transmission. Wireless transmitter.

(Section 8)
A multi-input multiple-output (MIMO) wireless receiver that separates signals received by multiple antennas and restores the transmitted signal transmitted from the wireless transmitter has a means for measuring the number of receptions of the same signal. The radio receiver performs signal separation in response to receiving the signal a predetermined number of times.

1 shows a conceptual diagram of a MIMO wireless communication system according to an embodiment of the present invention. FIG. It is a figure which shows the mode of the signal transmission by one Example of this invention. It is a figure which shows the mode of the signal transmission by one Example of this invention. It is a conceptual diagram for demonstrating another Example. It is a conceptual diagram for demonstrating another Example. It is a conceptual diagram for demonstrating another Example. 1 shows a conceptual diagram of a wireless communication system according to an embodiment of the present invention. It is a figure which shows a mode that a replica set is produced | generated in one Example of this invention. It is a figure which shows a mode that a replica set is produced | generated in one Example of this invention. It is a figure which shows a mode that the signal interleaved in one Example of this invention is transmitted.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Wireless communication system 102 Wireless transmitter 104 Wireless receiver 106 Diversity transmission control part 108 Diversity reception control part 402,404 Antenna 702 Wireless transmitter 704 Wireless receiver 706 Signal separation processing part 708 Subtractor 802 Error detector 804 Replica generation part 902 Multiplier 904 Replica generation unit

Claims (4)

In a multi-input multiple-output (MIMO) wireless receiver that receives multiple transmission signals transmitted from multiple antennas with multiple antennas,
First estimation means for estimating each of the transmission signals from a plurality of reception signals received by a plurality of antennas;
A plurality of subtracting means, wherein each subtracting means applies an estimated channel impulse response value to one received signal included in the plurality of received signals and to at least one transmission signal estimated by the first estimating means. A plurality of subtracting means for obtaining a difference from the multiplied one;
A radio receiver comprising: second estimation means for estimating transmission signals transmitted from a plurality of antennas based on a plurality of differences obtained by a plurality of subtraction means. The radio receiver according to claim 1, further comprising error detection means for detecting errors of a plurality of transmission signals estimated by the first estimation means. 2. The radio receiver according to claim 1, further comprising: an error correction unit that corrects errors of a plurality of transmission signals estimated by the first estimation unit and outputs a likelihood based on an error correction result.   The radio receiver according to claim 1, wherein a plurality of signal blocks included in at least one received signal are transmitted in an order rearranged by an interleaver.

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