JP5119413B2 - Wireless network - Google Patents

Description

  The present invention relates to a wireless network, and more particularly, to a wireless network including an access point and a wireless device that accesses the access point.

  Wireless LANs (Local Area Networks) are widely used in hot spots such as schools and event venues. However, disconnection of the direct link between the mobile terminal and the access point may occur due to the movement of the mobile terminal and the instantaneous fluctuation of the radio wave propagation state. For the same reason, when the quality of the radio link between the mobile terminal and the access point deteriorates, the number of retransmissions increases rapidly and the packet loss also increases. Such a direct link disconnection, an increase in retransmission, and an increase in packet loss have a serious adverse effect on the throughput of the entire network.

  In order to solve such problems, conventionally, the link quality between a mobile terminal and an access point is measured by RTS (Request To Send) and CTS (Clear To Send), and transmission is performed using the measured link quality. Calculate the rate and compare the total transmission time when the terminal directly accesses the access point using the calculated transmission rate and the total transmission time when the terminal accesses the access point via the repeater. A method for determining whether or not to use the selected repeater is proposed (Non-Patent Document 1).

Also, a technique for relaying wireless communication using network coding has been proposed (Non-Patent Document 2).
Hao Zhu, Guohong Cao, rDCF: a relay-enabled medium access control protocol for wireless ad hoc networks, INFOCOM'05, Vol. 1, pp. 12-22, 2005. Y.-D. Chen, S. Kishore, and J. Li, Wireless diversity through network coding, WCNC, Vol. 3, pp. 1681-1686, 2006.

   However, since the method disclosed in Non-Patent Document 1 is intended only for a single flow, the efficiency is poor. In the method disclosed in Non-Patent Document 2, the receiving terminal cannot decode a received packet if an error occurs in two or more of the received three packets. As a result, there is a problem that communication reliability is lowered.

  Accordingly, the present invention has been made to solve such a problem, and an object thereof is to provide a wireless network capable of improving the reliability of communication.

  According to the present invention, the wireless network includes a first wireless device, a second wireless device, a third wireless device, and a fourth wireless device. The third wireless device calculates a first parity check bit, which is a parity check bit of the first message, and adds the calculated first parity check bit to the first message to generate a first packet. And the generated first packet is transmitted to the first and second wireless devices. The fourth wireless device calculates a second parity check bit, which is a parity check bit of the second message, and adds the calculated second parity check bit to the second message to generate a second packet. And the generated second packet is transmitted to the first and second radio apparatuses. Then, the second radio apparatus receives the first and second packets, decodes the first and second messages based on the received first and second packets, and decodes the first and second packets. The exclusive OR of the second message is calculated to generate the third message, the third parity check bit that is the parity check bit of the third message is calculated, and the calculated third parity check A bit is added to the third message to generate a third packet, and the generated third packet is transmitted to the first wireless device. The first wireless device receives the first to third packets, performs a decoding process on the first to third messages based on the received first to third packets, When only one message among the first to third messages can be correctly decoded, the logarithmic likelihood indicating one message of the two messages that could not be decoded correctly by using the one message that was correctly decoded. A frequency ratio is calculated, and a channel decoding process for returning the parity check bit to the original information is performed on the calculated log likelihood ratio, so that one message is correctly decoded, and one message and one message are When the exclusive OR is calculated to correctly decode the other message of the two messages and all of the first to third messages cannot be correctly decoded, the first to third packets are decoded. The first to third log-likelihood ratios are calculated based on the first to third received signals that are the received signals, and the calculated first log-likelihood ratio and third log-likelihood ratio are calculated. A fourth log likelihood ratio indicating the second message is calculated based on the second log likelihood ratio, and a fifth log likelihood indicating the first message is calculated based on the second log likelihood ratio and the third log likelihood ratio. A first log likelihood ratio and a fifth log likelihood ratio are input to perform channel decoding processing to calculate a first log likelihood ratio, and the second log likelihood ratio and the first log likelihood ratio Channel decoding is performed with the log likelihood ratio of 4 as an input, and the process of calculating the second log likelihood ratio is repeatedly executed a predetermined number of times to correctly decode the first and second messages.

  According to the invention, the wireless network includes the first wireless device, the second wireless device, the third wireless device, and the fourth wireless device. The third wireless device calculates a first parity check bit, which is a parity check bit of the first message, and adds the calculated first parity check bit to the first message to generate a first packet. And the generated first packet is transmitted to the first and second wireless devices. The fourth wireless device calculates a second parity check bit, which is a parity check bit of the second message, and adds the calculated second parity check bit to the second message to generate a second packet. And the generated second packet is transmitted to the first and second wireless devices. Then, the second radio apparatus receives the first and second packets, decodes the first and second messages based on the received first and second packets, and decodes the first and second packets. The third message is generated by calculating the exclusive OR of the second message, interleaved with the third message, and a third parity check bit of the third message subjected to the interleaving. The parity check bit is calculated, a third packet including the calculated third parity check bit is generated, and the generated third packet is transmitted to the first radio apparatus. In addition, the first wireless device receives the first to third packets, and indicates the first message indicating the third message from the first and second received signals that are the received signals of the first and second packets. A log likelihood ratio is calculated, a second log likelihood ratio indicating a third parity check bit is calculated from the received signal when the third packet is directly received, and the calculated first and second log likelihoods are calculated. Decoding a third message based on the degree ratio, and using the third message that has been correctly decoded, calculating a third log likelihood ratio indicating one of the first and second messages; A channel decoding process for returning the parity check bit to the original information is performed on the calculated third log likelihood ratio to correctly decode one message, and the exclusive OR of the third message and one message To calculate the two The other message is correctly decoded the message.

  Furthermore, according to the present invention, the wireless network includes a first wireless device, a second wireless device, a third wireless device, and a fourth wireless device. The third wireless device calculates a first parity check bit, which is a parity check bit of the first message, and adds the calculated first parity check bit to the first message to generate a first packet. And the generated first packet is transmitted to the first and second wireless devices. The fourth wireless device calculates a second parity check bit, which is a parity check bit of the second message, and adds the calculated second parity check bit to the second message to generate a second packet. And the generated second packet is transmitted to the first and second wireless devices. Then, the second radio apparatus receives the first and second packets, decodes the first and second messages based on the received first and second packets, and decodes the first and second packets. The third message is generated by calculating the exclusive OR of the second message, interleaved with the third message, and a third parity check bit of the third message subjected to the interleaving. The parity check bit is calculated, the calculated third parity check bit is added to the third message to generate a third packet, and the generated third packet is transmitted to the first wireless device. . In addition, the first wireless device receives the first to third packets, and indicates the first message indicating the third message from the first and second received signals that are the received signals of the first and second packets. A log likelihood ratio is calculated, a second log likelihood ratio indicating the third message is calculated from a received signal when the third packet is directly received, and the calculated first and second log likelihood ratios are calculated. To obtain a third log likelihood ratio, and based on the obtained third log likelihood ratio and the fourth log likelihood ratio indicating the third parity check bit, the third message And the fifth log likelihood ratio indicating one of the first and second messages is calculated using the third message that has been correctly decoded, and the calculated fifth log likelihood Channel decoding process to return parity check bit to original information for ratio Subjected to decode one of the messages correctly, exclusive OR calculates decodes the two messages of the other message correctly with the third message and one message.

  Preferably, the first wireless device is an access point.

  Preferably, each of the third and fourth wireless devices is an access point.

  According to the present invention, the first wireless device can select one of the first to third messages based on the received signals of the first to third packets received from the second to fourth wireless devices, respectively. Even when only one message can be decoded, or even when all of the first to third messages cannot be decoded, the first and second messages are correctly decoded.

  Accordingly, communication reliability can be improved.

  Further, according to the present invention, the second wireless device transmits only the parity check bit to the first wireless device instead of the original information. The first wireless device decodes only one message from the first to third messages based on the received signals of the first to third packets received from the second to fourth wireless devices, respectively. Even when the first and third messages cannot be decoded or when all of the first to third messages cannot be decoded, the first and second messages are correctly decoded.

  Therefore, communication reliability can be improved and communication efficiency can be improved.

  Embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 1 is a schematic diagram of a wireless network according to an embodiment of the present invention. The wireless network 10 according to the embodiment of the present invention includes an access point AP1 and wireless devices A, B, and R.

  The access point AP1 and the wireless devices A, B, R are arranged in the wireless communication space. The access point AP1 is connected to the Internet (not shown) by a wired cable. In addition, the wireless devices A, B, and R are disposed within the communication range of the access point AP1.

  Each of radio apparatuses A and B generates a packet to be transmitted to access point AP1, performs channel coding on the generated packet by a method described later, and transmits the channel-coded coding packet.

  Radio apparatus R receives packets from radio apparatuses A and B, performs network coding on the two received packets, and transmits the network-coded coding packet to access point AP1.

  The access point AP1 receives the coding packets from the wireless devices A, B, and R, and decodes the packets transmitted from the wireless devices A and B by a method described later based on the received three coding packets.

[Embodiment 1]
FIG. 2 is a schematic block diagram showing the configuration of the wireless device A shown in FIG. 1 in the first embodiment.

  Radio apparatus A includes antenna 1, channel coding means 2 and 3, channel decoding means 4, error check circuit 5, additional circuit 6, message receiving means 7, and message generating means 8.

  The antenna 1 receives a packet from the access point AP1 and the other wireless devices B and R, and outputs a received signal of the received packet to the channel decoding means 4.

  The antenna 1 receives a packet from the channel coding means 2 and transmits the received packet to the access point AP1 and the other wireless devices B and R.

  The channel coding means 2 belongs to the physical layer. The channel coding means 2 receives the packet from the additional circuit 6 and performs channel coding on the received packet by a method described later. Then, the channel coding means 2 transmits the coding packet subjected to the channel coding via the antenna 1.

  The channel coding means 3 belongs to the physical layer. The channel coding unit 3 receives the received signal from the channel decoding unit 4 and performs channel coding on the received signal by a method described later. Then, the channel coding unit 3 outputs the received signal subjected to the channel coding to the channel decoding unit 4.

  The channel decoding means 4 belongs to both a link / MAC (Media Access Control) layer and a physical layer. The channel decoding unit 4 receives a reception signal from the antenna 1 and receives a reception signal subjected to channel coding from the channel coding unit 3. Then, the channel decoding means 4 decodes the packet by a method described later based on the received signal and the received signal subjected to channel coding, and corrects the error of the decoded packet. Then, the channel decoding means 4 outputs the packet with the error corrected to the error checking circuit 5.

  The error checking circuit 5 belongs to the link / MAC layer and receives a packet from the channel decoding means 4. Then, the error check circuit 5 performs an error check on the received packet and outputs a message after the error check to the message receiving means 7.

  The additional circuit 6 belongs to the link / MAC layer. The addition circuit 6 receives the packet from the message generation unit 8, adds an error check code to the received message, and outputs the message with the error check code added to the channel coding unit 2.

  The message receiving means 7 receives the message from the error checking circuit 5, receives the message when the destination of the received message is the wireless device A, and when the destination of the received message is other than the wireless device A, The received message is output to the message generation means 8.

  The message generation means 8 generates a message addressed to the access point AP1 and outputs the generated message to the additional circuit 6. Further, when the message generation means 8 receives the message from the message reception means 7, the message generation means 8 performs network coding on the received message and outputs the network coded message to the additional circuit 6.

  Note that each of wireless devices B and R and access point AP1 shown in FIG. 2 has the same configuration as wireless device A shown in FIG.

  FIG. 3 is a circuit block diagram showing the configuration of the channel coding means 2 shown in FIG. The channel coding means 2 includes computing units 21 and 24, delay units 22 and 23, a coupling circuit 25, and a modulation circuit 26.

Calculator 21, a message _X iU from adding circuit 6 (i = A, B, R) to receive, receives the delayed message _X iU _D from delayer 22 receives a delayed message _X iU _2D from the delay circuit 23. Then, the arithmetic unit 21, a message _{X iU} and delay message _X iU _{_D,} calculates the exclusive OR of X iU _2D, and outputs the operation result to the delay unit 22.

In this case, the arithmetic unit 21, a message _{X iU} by calculating the exclusive OR of the message _{X iU} the delay message _X iU _D, calculates the exclusive OR of the calculation result to the delay message _X iU _2D And the exclusive OR of the delayed messages X _iU —D and X _iU —2D.

  The delay unit 22 delays the output of the computing unit 21 by the delay time D, and outputs the delayed output to the computing units 21 and 24 and the delay unit 23.

  The delay unit 23 delays the output of the delay unit 22 by a delay time D, and outputs the delayed output to the computing units 21 and 24.

The computing unit 24 computes the exclusive OR of the output of the computing unit 21 and the output of the delay unit 23, and outputs the computation result to the connection circuit 25. The output of the calculator 24 is the parity check bit X _iC = Γ (X _iU ) of the message X _iU that is an input.

The connection circuit 25 receives the message X _iU from the additional circuit 6 and receives the parity check bit X _iC = Γ (X _iU ) from the arithmetic unit 24. The concatenating circuit 25 concatenates the message X _iU and the parity check bit X _iC = Γ (X _iU ) to generate a bit sequence x (t), and the generated bit sequence x (t) is converted to the modulation circuit 26. Output to.

  The modulation circuit 26 modulates the bit sequence x (t) and transmits the modulated bit sequence x (t) via the antenna 1.

  FIG. 4 is a diagram for explaining a channel decoding process method. The channel coding means 2 performs channel coding of the input signal using the arithmetic units 21 and 24 and the delay units 22 and 23 shown in FIG.

In this case, the input signal is u _t and the output signal is x _t . Table 1 represents the state transition and Table 2 represents the coding output.

In Table 1, when the current state S ₁ S ₀ is “00”, if the input signal u _t is “0”, a transition is made to a new state S ₁ S ₀ = “00”, and the input signal u _t is If “1”, the state transits to a new state S ₁ S ₀ = “10”.

If the current state S ₁ S ₀ is “01” and the input signal u _t is “0”, the state transitions to a new state S ₁ S ₀ = “10”, and the input signal u _t is “1”. "", A transition is made to a new state S ₁ S ₀ = “00”.

Further, when the current state S ₁ S ₀ is “10”, if the input signal u _t is “0”, the state transits to a new state S ₁ S ₀ = “11”, and the input signal u _t is “1”. "", A transition is made to a new state S ₁ S ₀ = “01”.

Further, when the current state S ₁ S ₀ is “11” and the input signal u _t is “0”, the state transits to a new state S ₁ S ₀ = “01”, and the input signal u _t is “1”. "", A transition is made to a new state S ₁ S ₀ = “11”.

In Table 2, when the current state S ₁ S ₀ is “00”, the arithmetic unit 24 outputs the coding output x _t = “00” if the input signal u _t is “0”. If the input signal u _t is “1”, the coding output x _t = “11” is output.

When the current state S ₁ S ₀ is “01”, the arithmetic unit 24 outputs the coding output x _t = “00” if the input signal u _t is “0”, and the input signal u _t. If “1”, the coding output x _t = “11” is output.

Furthermore, if the current state _S 1 _{S 0} is "10", the arithmetic unit 24, if the input signal _{u t} is "0", and outputs the coded output _x t = "01", the input signal _{u t} If “1”, the coding output x _t = “10” is output.

Further, when the current state S ₁ S ₀ is “11”, the arithmetic unit 24 outputs the coding output x _t = “01” and the input signal u _t if the input signal u _t is “0”. If “1”, the coding output x _t = “10” is output.

Table 1 coding output x _t when the bit stream of the input signal is composed of "10010" will be explained with reference to Table 2 and FIG.

When the arithmetic unit 21 receives the first input signal u _t = “1” of the bit stream, the state transitions from the current state S ₁ S ₀ = “00” to the new state S ₁ S ₀ = “10”. The calculator 24 outputs the coding output x _t = “11” (see Table 2 and the arrow ARW1 in FIG. 4).

Thereafter, when the arithmetic unit 21 receives the second input signal u _t = “0” of the bit stream, the state changes from the current state S ₁ S ₀ = "10" to the new state S ₁ S ₀ = "11". After the transition (see Table 1), the arithmetic unit 24 outputs the coding output x _t = “01” (see Table 2 and the arrow ARW2 in FIG. 4).

Subsequently, when the arithmetic unit 21 receives the third input signal u _t = "0" of the bit stream, the state changes from the current state S ₁ S ₀ = "11" to the new state S ₁ S ₀ = "01". (See Table 1), the computing unit 24 outputs a coding output x _t = “01” (see Table 2 and arrow ARW3 in FIG. 4).

When the arithmetic unit 21 receives the fourth input signal u _t = “1” of the bit stream, the state changes from the current state S ₁ S ₀ = “01” to the new state S ₁ S ₀ = “00”. After the transition (see Table 1), the arithmetic unit 24 outputs the coding output x _t = “11” (see Table 2 and the arrow ARW4 in FIG. 4).

Thereafter, when the arithmetic unit 21 receives the fifth input signal u _t = “0” of the bit stream, the state changes from the current state S ₁ S ₀ = “00” to the new state S ₁ S ₀ = “00”. After the transition (see Table 1), the arithmetic unit 24 outputs the coding output x _t = “00” (see Table 2 and the arrow ARW5 in FIG. 4).

  As a result, the channel coding means 2 performs channel coding on the bit stream = “10010” by the arithmetic units 21 and 24 and the delay units 22 and 23, and outputs a coding output consisting of 11-01-01-11-00.

  Therefore, when performing channel decoding in which the channel coding unit 2 returns the coding output channel coded by the channel coding unit 2 to the original bit stream, the channel decoding unit 4 is based on channel coding output = “11-01-01-11-00”. A path represented by arrows ARW1 to ARW5 shown in FIG. 4 is specified, and channel coding output = “11-01-01-11-00” is returned to bit stream = “10010” and channel decoding is performed according to the specified path. To do.

More specifically, the channel decoding means 4 starts from the state S ₁ S ₀ = “00” according to the first coding output = “11” of the channel coding output = “11-01-01-11-00”. The transition to the state S ₁ S ₀ = “10” (see arrow ARW1) is specified, and the input signal u _t = indicating the transition from the state S ₁ S ₀ = “00” to the state S ₁ S ₀ = “10” “1” is detected.

Thereafter, the channel decoding means 4 changes the state S ₁ S ₀ = “10” to the state S ₁ according to the second coding output = “01” of the channel coding output = “11-01-01-11-00”. S ₀ = "11" identifies the transition to (see arrow ARW2), state _S 1 _S 0 = input signal _u t = "0" which indicates a transition to state from _{"10" S 1 S 0 =} "11" Is detected.

Subsequently, the channel decoding means 4 changes the state S ₁ S ₀ = “11” to the state S according to the third coding output = “01” of the channel coding output = “11-01-01-11-00”. identify ₁ transition to S ₀ = "01" (see arrow ARW3), state _S 1 _S 0 = "11" input signal _u t = "0 indicating a transition to the state _S 1 _S 0 =" 01 " ”Is detected.

Further, subsequently, the channel decoding means 4 starts from the state S ₁ S ₀ = “01” according to the fourth coding output = “11” of the channel coding output = “11-01-01-11-00”. The transition to the state S ₁ S ₀ = “00” (see arrow ARW4) is specified, and the input signal u _t = indicating the transition from the state S ₁ S ₀ = “01” to the state S ₁ S ₀ = “00” “1” is detected.

Further, subsequently, the channel decoding means 4 starts from the state S ₁ S ₀ = “00” according to the fifth coding output = “00” of the channel coding output = “11-01-01-11-00”. state _S 1 _S 0 = identify "00" transition to (see arrow ARW5), state _S 1 _S 0 = input signal indicating the transition of the "00" from the state _{S 1 S 0 = "00"} u t = “0” is detected.

  As a result, the channel decoding means 4 performs channel decoding of the channel coding output = “11-01-01-11-00” to the bit stream = “10010”.

  Therefore, the channel decoding means 4 holds the lattice structure shown in FIG. 4 in advance, and channel decodes the channel coding output into a bit stream with reference to the lattice structure.

A method in which wireless devices A and B transmit messages X _AU and X _BU to access point AP1 will be described.

The message generation means 8 of the wireless device A generates a message X _AU addressed to the access point AP 1 and outputs the generated message X _AU to the additional circuit 6. Then, the additional circuit 6 of the wireless device A receives the message X _AU from the message generation means 8, adds an IEEE 802.11 error check code CRC-32 to the received message X _AU , and adds the error check code. The added message X _AU is output to the channel coding means 2.

Thereafter, the channel coding means 2 of the wireless device A receives the message X _AU from the additional circuit 6 and generates a bit sequence X _A according to the following expression based on the received message X _AU .

That is, the channel coding means 2 of the wireless device A performs the channel coding of the message X _AU by the method described above to generate the parity check bit X _AC = Γ (X _AU ), and the message X _AU and the parity check bit X _AC = Γ (X _AU ) is concatenated to generate a bit sequence X _A.

Then, the channel coding means 2 of the wireless device A modulates the bit sequence X _A by substituting the bit sequence X _A into x _i (t) of the following equation and calculating the signal ψ _A (t).

Then, the channel coding means 2 of the wireless device A transmits a signal ψ _A (t) obtained by modulating the bit sequence X _A.

Similarly to the wireless device A, the wireless device _B transmits a signal ψ _B (t) obtained by modulating the bit sequence X _B.

The wireless devices A and B transmit a signal ψ _A (t) and a signal ψ _B (t), respectively, by a CSMA (Carrier Sense Multiple Access) method or a TDMA (Time Division Multiple Access) method.

Channel decoding means 4 of the radio device R, the signal ψ _A (t), receives ψ _B (t), the received signal ψ _A (t), demodulates the ψ _B (t), the signal [psi was demodulated _The messages X ′ _AU and X ′ _BU are calculated by channel decoding _A (t) and ψ _B (t) by the method described above.

Then, channel decoding means 4 of the radio device R, the message X _'AU, X' and correct errors _BU, and outputs the message X _'AU, X' after the error correction _BU to the error check circuit 5.

Then, the error check circuit 5 of the wireless device R performs error check of the messages X ′ _AU and X ′ _BU using the error check code CRC-32 added after the messages X ′ _AU and X ′ _BU . Then, the error check circuit 5 of the wireless device R outputs error check messages X _AU and X _BU to the message receiving means 7.

Message receiving means 7 of the wireless device R receives message _{X AU,} the _{X BU} from the error check circuit 5 detects that the received message _{X AU,} the destination of _{X BU} is an access point AP1, the message _{X AU,} X _BU is output to the message generation means 8.

Then, the message generation means 8 of the wireless device R receives the messages X _AU and X _BU from the message reception means 7 and calculates the exclusive OR of the received messages X _AU and X _BU to generate the message X _RU. The generated message _XRU is output to the additional circuit 6.

Then, the addition circuit 6 of the wireless device R appends the error check code CRC-32 behind the message _{X RU,} and outputs the message _{X RU} added with error check code CRC-32 to the channel coding means 2.

Then, the channel coding means 2 of the wireless device R calculates the bit sequence X _R by substituting the message X _RU into the equation (1), and the calculated bit sequence X _R is converted to x _i (t) of the equation (2). And signal ψ _R (t) is calculated. Then, the channel coding means 2 of the wireless device R transmits the signal ψ _R (t) via the antenna 1.

The channel decoding means 4 of the access point AP1 receives the signal ψ _A (t) from the wireless device A, receives the signal ψ _B (t) from the wireless device B, and receives the signal ψ _R (t) from the wireless device R. To do.

Channel gain in radio link L _A-AP1 between radio apparatus A and access point AP1, channel gain in radio link L _B-AP1 between radio apparatus B and access point AP1, radio apparatus R and access point AP1 Channel gains in the radio link L _R-AP1 between h _A , h _B and h _R , respectively. In addition, the noise signals on the radio links L _A-AP1 , _{LB -AP1} and _LR-AP1 are n _A , n _B and n _R , respectively, and the powers of n _A , n _B and n _R are all equal to σ ² . And

If the received signals of the signal ψ _A (t), the signal ψ _B (t), and the signal ψ _R (t) are s _A , s _B , and s _R , respectively, the received signals s _A , s _B , and s _R are It can be expressed by the following formula.

Thereafter, the channel decoding means 4 of the access point AP1 obtains signals ψ _A (t), ψ _B (t), ψ _R (t) from the received signals s _A , s _B , s _R. In this case, for example, if s _A > 0, the channel decoding means 4 of the access point AP1 sets ψ _A (t) = 1, and if s _A ≦ 0, the signal is set as ψ _A (t) = − 1. ψ _A (t) is obtained. Similarly, the channel decoding means 4 of the access point AP1 obtains signals ψ _A (t), ψ _B (t), ψ _R (t). Then, the channel decoding means 4 of the access point AP1 performs channel decoding of the obtained signals ψ _A (t), ψ _B (t), ψ _R (t) by the method described above, and messages X _AU , X _BU , X _{Get RU} .

(I) When only one of the messages X _AU , X _BU , and X _RU is correctly decoded The channel decoding means 4 of the access point AP1 substitutes the received signals s _A , s _B , and s _R into the following equation The log likelihood ratios L _A , L _B , and _LR are calculated.

Then, the channel decoding means 4 of the access point AP1 sets one message that has been correctly decoded as a message _XRU, and outputs the message _XRU to the channel coding means 3. Channel coding means 3 of the access point AP1 receives the message _{X RU} from the channel decoding unit 4 obtains a bit sequence _{X R} by substituting the received message _{X RU} in equation (1). Then, channel coding means 3 of the access point AP1, it outputs a bit sequence X _R to channel decoding unit 4.

Thereafter, the channel decoding unit 4 of the access point AP1 receives the bit sequence X _R from the channel coding unit 3, and the log likelihood ratios L _A and L _B are respectively expressed by the following equations L _A (t) and L _B (t). Substituting and substituting the bit sequence X _R into x _R (t) in the following equation, the log likelihood ratio L ″ _A (t) indicating the message X _AU is obtained.

Since the first term on the right side of Equation (5) indicates the log likelihood ratio of message X _AU , Equation (5) represents the log likelihood ratio of message X _AU .

Accordingly, channel decoding means 4 of the access point AP1, using Equation (5), a message _X AU that could not be decoded _correctly, the log likelihood ratio _{L "A} indicating one of the message _{X AU} of _{X BU} (t) of Ask.

When the channel decoding means 4 of the access point AP1 obtains the log likelihood ratio L ″ _A (t), it performs channel decoding on the obtained log likelihood ratio L ″ _A (t) by the above-described method to generate the message X _AU . get.

Then, channel decoding section 4 of the access point AP1 decrypts the message _{X BU} calculates the message _{X AU,} the exclusive OR of the message _{X RU.}

Then, channel decoding section 4 of the access point AP1, the message _{X AU,} performs error correction of _{X BU,} and outputs the message _X AU after the error _correction, the _{X BU} to the error check circuit 5, the error checking circuit 5, message _{X AU,} the message _X AU by using the error check code CRC-32, which is appended to the _{X BU,} examine the errors in _{X BU,} message _X AU after the error _checking, the _{X BU} to the message receiving means 7 Output. Then, the message receiving means 7 of the access point AP1 receives the messages X _AU and X _BU from the error check circuit 5, detects that the destination of the received messages X _AU and X _BU is the access point AP1, and receives the message X _AU and _XBU are accepted.

As a result, the access point AP1 can correctly receive the messages X _AU and X _BU transmitted from the wireless devices A and B.

In Embodiment 1, the channel decoding means 4 of the access point AP1 changes the log likelihood ratio L _B (t) of the first term on the right side of the equation (5) to the log likelihood ratio L _A (t). The log likelihood ratio L _A (t) of the second term on the right side of the equation (5) is changed to the log likelihood ratio L _B (t), and the log likelihood ratio L ″ _B (t) of the message X _BU is changed. In this case, the channel decoding means 4 of the access point AP1 obtains the message X _BU by channel decoding the log likelihood ratio L ″ _B (t) by the method described above, and the message X _The message _XAU is decoded by calculating an exclusive OR of the _BU and the message _XRU .

In addition, a method of decoding the messages X _AU and X _BU by the above-described method is referred to as “Maximal ratio combining”.

(Ii) When all of the messages X _AU , X _BU , and X _RU cannot be decoded correctly The channel decoding means 4 of the access point AP1 substitutes the received signals s _A , s _B , and s _R into the equation (4) to logarithmic The degree ratios L _A , L _B and _LR are calculated.

FIG. 5 is a schematic diagram showing the configuration of the decoding circuit held by the channel decoding means 4 shown in FIG. When all of the messages X _AU , X _BU , and X _RU cannot be decoded correctly, the channel decoding means 4 of the access point AP1 decodes the messages X _AU and X _BU using the decoding circuit 40 shown in FIG.

  The decoding circuit 40 includes SISO (Soft Input Soft Output) decoders 41 to 43, calculators 44 and 45, and determiners 46 and 47.

The SISO decoder 41 receives the log likelihood ratio L _A = [L _AU , L _AC ] in the first calculation, and the received log likelihood ratio L _A = [L _AU , L _AC ] by a method described later. The logarithmic likelihood ratio / L _AU of the message X _AU is output to the calculator 44 and the determiner 46 after decoding. The notation / L _AU represents L with the bar shown in FIG. 5 drawn upward.

The SISO 41 receives the log likelihood ratio L _A = [L _AU , L _AC ] in the second and subsequent calculations, receives the log likelihood ratio L ′ _AU from the calculator 45, and receives the log likelihood ratio L _A = _{[L AU,} L _AC] and based on the log likelihood ratio L _'AU calculates a log likelihood ratio _{/ L AU} and _{L e} of the message _{X AU,} the calculator and the log-likelihood ratio _{/ L AU} that computed 44 and the determiner 46.

In the first calculation, the SISO decoder 42 receives the log likelihood ratio L _B = [L _BU , L _BC ], and receives the log likelihood ratio L _B = [L _BU , L _BC ] by a method described later. The logarithmic likelihood ratio / L _BU of the message X _BU is output to the calculator 45 and the determiner 47 after decoding.

The SISO 42 receives the log likelihood ratio L _B = [L _BU , L _BC ] in the second and subsequent calculations, receives the log likelihood ratio L ′ _BU from the calculator 44, and receives the log likelihood ratio L _B = _{[L BU,} L _BC] and log likelihood ratio L 'based on the _BU calculates the log likelihood ratio _{/ L BU} and _{L e} of the message _{X BU,} log likelihood ratio _{/ L BU} a calculator that the calculated 45 and the determination unit 47.

SISO decoder 43, the log likelihood ratio _{L R = [L RU, L} RC] undergo, the received log likelihood ratios _{L R = [L RU, L} RC] message _{X RU} by decoding by a method to be described later and outputs the LLR _{/ L RU} to the arithmetic unit 44.

The computing unit 44 receives the log likelihood ratio / L _AU from the SISO decoder 41 and the log likelihood ratio / L _RU from the SISO decoder 43. Then, the computing unit 44 computes the log likelihood ratio L ′ _BU (t) by the following equation based on the log likelihood ratios / L _AU , / L _RU , and the calculated log likelihood ratio L ′ _BU ( t) is output to the SISO decoder 42.

That is, the calculator 44 calculates a log likelihood ratio _{/ L AU} illustrating message _{X AU,} the log likelihood ratio L _'BU illustrating message _{X BU} and a log likelihood ratio _{/ L RU} illustrating message _{X RU} .

The arithmetic unit 45 receives the log likelihood ratio / L _BU from the SISO decoder 42 and the log likelihood ratio / L _RU from the SISO decoder 43. Then, the computing unit 45 computes a log likelihood ratio L ′ _AU (t) based on the log likelihood ratios / L _BU , / L _RU by the following equation, and the calculated log likelihood ratio L ′ _AU ( t) is output to the SISO decoder 41.

That is, the computing unit 45 computes a log likelihood ratio _{/ L BU} illustrating message _{X BU,} the log likelihood ratio L _'AU illustrating message _{X AU} and a log likelihood ratio _{/ L RU} illustrating message _{X RU} .

The determiner 46 receives the signal / L _AU from the SISO decoder 41, converts the received signal / L _AU into a bit value (“1” or “0”), and outputs a message X _AU .

The determination unit 47 receives the signal / L _BU from the SISO decoder 42, converts the received signal / L _BU into a bit value (“1” or “0”), and outputs a message X _BU .

  FIG. 6 is a diagram for explaining a decoding method in SISO decoder 41 shown in FIG.

Let u ₁ , u ₂ ,..., U _t be input bit sequences of the channel coding means 2 on the transmission side. Channel coding means 2 on the transmission side, with respect to _{u t,} when the ^{_{u t = + 1, x +}} t = (x + t, 1, x + t, 2, ···, x + t, n) the , U _t = −1, x− _t = (x− _{t, 1} , x− _{t, 2} ,..., X− _{t, n} ) is output. When the transmission side channel coding means 2 is composed of the circuit shown in FIG. 3, if u _t = + 1, x ⁺ _t = (x ⁺ _{t, 1} , x ⁺ _{t, 2} ) and u _t = −1. If so, x- _t = (x- _{t, 1} , x- _{t, 2} ) is output.

It is assumed that reception or signal on the receiving side is y _t = (y _{t, 1} , y _{t, 2} ,..., Y _{t, n} ). s is the state S ₁ S ₀ . The transition from s _{i at} time t-1 to s _{j at} time t is called a branch. In the following, the signal +1 corresponds to the bit “1”, and the signal −1 corresponds to the bit “−1”.

The branch metric at time t is β ⁺ _t when u _t = + 1, β ⁻ _t when u _t = −1, and the state metric of path i at time t is M ⁽ⁱ⁾ _t .

  The branch metric at time t is expressed by the following equation.

In equation (8), L _c (y _{t, k} ) = (2E _s / N ₀ ) y _{t, k} is a soft demodulation result, and (2E _s / N ₀ ) is a signal calculated by the gain of the received signal The noise to noise ratio.

  Then, the state metric at time t is calculated by the following equation.

  In this case, at time t, only the path with the maximum metric remains in all paths to one state. At time t + δ (δ is the update interval), the original bit up to time t is determined by the path path (i) with the largest metric among the remaining four paths to the four states.

For the remaining path path (i) at time t + δ, the state of the l-th stage in δ + 1 states from t + 0 to t + δ is represented by s ^(il) . In the l-th stage, a path having the largest metric among other paths excluding the path path (i) is referred to as a competitive path. ^Let s ^(i′l) be the state of the competitive path. Then, the difference between the metric of the path path (i) and the competitive path in the l-th state is expressed by the following equation.

The output of decoding by SOVA (Soft Output Viterbi Algorithm) is expressed by the following equation. Min operation in equation (10), and _{u t + 1} decoded by the path path (i) in l-th stage, considered only when _{the u t + 1} decoded by the competition path is different.

  And the external information produced | generated by channel decoding is represented by following Formula.

Therefore, the SISO decoder 41 receives the log likelihood ratio L _A (t) as the input L _c , receives the log likelihood ratio L ′ _AU as the input L _apriori , and receives the input L _c = L _A (t), based on the _{L 'AU} = L _apriori, and outputs an output _{/ L AU} consisting of _{L SOVA,} an output _{L e.}

SISO decoder 42, by the same method as SISO decoder _41, and outputs an output _{/ L BU} consisting _{L SOVA,} an output _{L e.} The SISO decoder 43 also outputs / L _RU by the same method as the SISO decoder 41.

Channel decoding means 4 of the access point AP1, the log likelihood ratio _{L A,} L B, when calculating the _{L R,} the calculated log likelihood ratio _{L A,} L B, the _{L R} to a decoding circuit 40 shown in FIG. 5 Input and perform a predetermined number of times (for example, 10 times) to decode the messages X _AU and X _BU .

As described above, even when all of the messages X _AU , X _BU , and X _RU cannot be decoded, the messages X _AU and X _BU can be decoded by using the decoding circuit 40 shown in FIG.

  Note that the decoding method according to the above-described method is referred to as “iterative decoding”.

(Iii) Message _{X AU, X BU,} of the _{X RU,} If you can decode more than one message correctly message _{X AU, X BU,} of the _{X RU,} 2 single message _{X AU, X BU} can correctly decode Or when all of the messages X _AU , X _BU , and X _RU are correctly decoded, the channel decoding means 4 of the access point AP1 acquires the messages X _AU and X _BU transmitted from the wireless devices A and B, respectively. Therefore, the acquired messages X _AU and X _BU are output to the error check circuit 5.

If two messages X _AU and X _RU can be correctly decoded among the messages X _AU , X _BU , and X _RU , the channel decoding means 4 of the access point AP1 exclusive of the message X _AU and the message X _RU A logical sum is calculated to decode the message _XBU .

Furthermore, when the two messages X _BU and X _RU can be correctly decoded among the messages X _AU , X _BU and X _RU , the channel decoding means 4 of the access point AP1 excludes the message X _BU and the message X _RU exclusively. The logical sum is calculated to decode the message _XAU .

In this way, when two or more messages can be correctly decoded among the messages X _AU , X _BU , and X _RU , the channel decoding means 4 of the access point AP 1 has three messages X _AU , X _BU , and X _RU. Are independently decoded.

FIG. 7 is a flowchart for explaining the decoding method according to the first embodiment. When a series of operations is started, the access point AP1 receives the reception signals s _A , s _B , and s _R of the messages X _AU , X _BU , and X _RU from the wireless devices A, B, and R, respectively (step S1). .

Then, the channel decoding means 4 of the access point AP1 decodes the received signals s _A , s _B , and s _R (step S2), and uses the received signals s _A , s _B , and s _R using equation (4). Log likelihood ratios L _A , L _B , and _LR are calculated (step S3).

Thereafter, the channel decoding means 4 of the access point AP1 determines whether or not two or more messages among the messages X _AU , X _BU , and X _RU have been correctly decoded (step S4).

In step S4, when it is determined that two or more messages can be correctly decoded among the messages X _AU , X _BU , and X _RU , the channel decoding unit 4 of the access point AP1 determines the three messages X _AU , X _BU , X _RU are independently decoded (step S5).

On the other hand, when it is determined in step S4 that two or more messages out of the messages X _AU , X _BU , and X _{RU have} not been correctly decoded, the channel decoding unit 4 of the access point AP1 determines that the message X _AU , X _BU , X _RU , it is further determined whether only one message has been correctly decoded (step S6).

In step S6, when it is determined that only one message can be correctly decoded among the messages X _AU , X _BU , and X _RU , the channel decoding means 4 of the access point AP1 determines one message that has been correctly decoded. The messages X _AU and X _BU are decoded by the above-described method (Maximal Ratio Combining) (step S7).

On the other hand, when it is determined in step S6 that only one message among the messages X _AU , X _BU , and X _RU has not been correctly decoded, the channel decoding means 4 of the access point AP1 determines the log likelihood ratio L _A , L _B and L _R , the messages X _AU and X _BU are decoded by the above-described method (Iterative decoding) (step S8).

  And after any of step S5, step S7, and step S8, a series of operation | movement is complete | finished.

As described above, in the first embodiment, only one message out of the three messages X _AU , X _BU , X _RU from the wireless devices A, B, R can be decoded correctly, or 3 Even when all of the messages X _AU , X _BU , and X _RU cannot be correctly decoded, the messages X _AU and X _BU are correctly decoded.

  Accordingly, communication reliability can be improved.

[Embodiment 2]
FIG. 8 is a schematic block diagram showing the configuration of the radio apparatuses A, B, and R shown in FIG. 1 in the second embodiment.

  The wireless devices A, B, and R shown in FIG. 1 are composed of the wireless device A-1 shown in FIG. 8 in the second embodiment. The wireless device A-1 is obtained by replacing the channel coding unit 2 of the wireless device A shown in FIG. 2 with the channel coding unit 2A and replacing the channel decoding unit 4 with the channel decoding unit 4A. The same.

If the wireless device A-1 is a wireless device R, channel coding means 2A receives the message _{X RU} from adding circuit 6, the received message _{X RU} calculates Π the _{(X RU)} to the message _{X RU} Interleave.

Thereafter, channel coding means 2A calculates Γ (Γ (X _RU )) using the same channel coding method as channel coding means 2. This Γ (Π (X _RU )) represents the parity check bit of the interleaved message X _RU .

Then, channel coding means 2A modulates signal ψ _R (t) composed of Γ (Π (X _RU )) using equation (2), and transmits the modulated signal ψ _R (t) to access point AP1. To do.

When the wireless device A-1 is the wireless device A or the wireless device B, the channel coding unit 2A performs channel coding of the message X _AU or the message X _BU by the same method as the channel coding unit 2 to the access point AP1. Send.

As described above, in the second embodiment, the radio apparatus R that is a repeater performs parity check bit = Γ (Π (Π () of the message X _RU obtained by calculating the exclusive OR of the messages X _AU and X _{BU. XRU} )) only is transmitted to the access point AP1.

  Therefore, communication can be made efficient.

The channel decoding means 4A uses the equation (4) to logarithmize the received signal s _A of the message X _AU transmitted from the wireless device _A and the received signal s _B of the message X _BU transmitted from the wireless device B, respectively. Likelihood ratios L _A and L _B are calculated.

Then, the channel decoding means 4A substitutes the calculated log likelihood ratios L _A and L _B into the following equation to calculate the log likelihood ratio L ′ for the bit sequence X _R = [X _RU , X _RC ] of the message X _{RU. R} is calculated.

That is, the channel decoding means 4A calculates a log likelihood ratio L ′ _R representing the message X _RU from the log likelihood ratio L _A representing the message X _AU and the log likelihood ratio L _B representing the message X _BU .

Thereafter, the channel decoding means 4A calculates the received signal s ′ _R = [s ′ _RU , s ′ _RC ] of the message X _RU by substituting the calculated log likelihood ratio L ′ _R into the following equation.

Then, the channel decoding unit 4A calculates the log likelihood ratio / L _RU of the message X _RU by a method described later based on the received signal s ′ _R = [s ′ _RU , s ′ _RC ] and the received signal s _R. The calculated log likelihood ratio / L _RU is determined to be bit “1” or bit “0”, and the message X _RU is decoded. Then, the channel decoding unit 4A decodes the messages X _AU and X _BU by using the above-described Maximum Ratio Combining or Iterative Decoding using the message X _RU .

  Note that the access point AP1 shown in FIG. 1 also has the same configuration as that of the wireless device A-1 shown in FIG.

  FIG. 9 is a schematic diagram showing a configuration of a decoding circuit held by the channel decoding means 4A shown in FIG. The channel decoding means 4A holds the decoding circuit 50 shown in FIG. Decoding circuit 50 includes arithmetic circuits 51 to 54, SISO decoders 55 and 57, interleave circuit 56, deinterleave circuits 58 and 59, and a determiner 60.

The arithmetic circuit 51, the received signal _{s A} calculates the log likelihood ratios _{L A} of substituted into _s i (t) received signal _{s A} of the formula (4), calculating the calculated log likelihood ratios _{L A} Output to the circuit 53.

Calculation circuit 52 substitutes the _s i (t) calculates the log likelihood ratio _{L B} of the received signal _{s B} of formula (4) the received signal _{s B,} calculating the calculated log likelihood ratio _{L B} Output to the circuit 53.

The arithmetic circuit 53 calculates the log likelihood ratio L ′ _R by the equation (13) based on the log likelihood ratio L _A and the log likelihood ratio L _B, and the calculated log likelihood ratio L ′. _R is output to the SISO decoder 55.

Arithmetic circuit 54, the received signal _{s R} a calculates the log likelihood ratio _{L RC} of substituted into _s i (t) the received signal _{s R} of formula (4), the calculated log likelihood ratio _{L RC} SISO Output to L _{c of the} decoder 57.

The SISO decoder 55 calculates the log likelihood ratio / L _RU by the same method as the SISO decoder 41 based on the log likelihood ratios L ′ _RU and L ′ _RC and the output signal of the deinterleave circuit 58. The calculated log likelihood ratio / L _RU is output to the interleave circuit 56.

Interleave circuit 56 interleaves the LLR _{/ L RU,} and outputs the interleaved log likelihood ratio _{/ L RU} to SISO decoder 57.

SISO decoder 57 calculates L _e and L _SOVA based on the output of interleave circuit 56 and the log likelihood ratio L _RC from calculation circuit 54, and outputs the calculated L _e to deinterleave circuit 58. , L _SOVA = / L _RU is output to the deinterleave circuit 59.

Deinterleave circuit 58 deinterleaves the _{L e,} and outputs the de-interleaved _{L e} to SISO decoder 55.

Deinterleave circuit _59, L SOVA = _/ a _{L RU} deinterleaves, and outputs the de-interleaved _L SOVA = _{/ L RU} to determiner 60.

The determinator 60 receives the deinterleaved L _SOVA = / L _RU from the deinterleave circuit 59, determines the received L _SOVA = / L _RU to bit “1” or bit “0”, and outputs a message X _RU To do.

As described above, the channel decoding means 4A decodes the message _XRU using the decoding circuit 50 shown in FIG. 9 based on the received signals s _A , s _B , and s _R.

And since the channel decoding means 4A was able to correctly decode only one message _XRU among the messages _XAU , _XBU , and _XRU , the channel decoding means 4A is implemented based on the one message _XRU that has been correctly decoded. The messages X _AU and X _BU are decoded using the Maximum Ratio Combining described in the first embodiment.

That is, the channel decoding means 4A outputs the message _{X RU} to the channel coding unit 3 receives a bit sequence _{X R} message _{X RU} from the channel coding unit 3. Then, the channel decoding unit 4A decodes the messages X _AU and X _BU by the above-described method based on the log likelihood ratios L _A and L _B and the bit sequence X _R.

FIG. 10 is a flowchart for explaining the decoding method according to the second embodiment. When a series of operations starts, the access point AP1 receives the received signals s _A , s _B , and s _R of the messages X _AU , X _BU , and X _RU from the wireless devices A, B, and R, respectively (step S11). . In this case, the received signal s _A is a received signal of a signal composed of a message X _AU and a parity check bit X _AC of the message X _AU , and the received signal s _B is a parity check bit X of the message X _BU and the message X _{BU. The} reception signal s _R is a reception signal of a signal consisting of a parity check bit X _RC of the message _XRU .

Then, channel decoding means 4A of the access point AP1, the received signal _{s A,} s B, _s each of _R log-likelihood ratios _{L A,} L B, calculates the _{L R} (step S12).

Thereafter, the channel decoding means 4A of the access point AP1 calculates the log likelihood ratio L ′ _R by substituting the log likelihood ratios L _A and L _B into the equation (13) (step S13).

In this case, _RU 'L of _R' log likelihood ratio L represents a message _{X RU, RC} 'L of _R' log likelihood ratio L represents a parity check bits = gamma message _{X RU (X RU)} .

Then, channel decoding means 4A of the access point AP1, the log likelihood ratio L _'RU, L' _RC, based on _{L R,} by the above-described method, decoding the message _{X RU} (step S14).

Thereafter, the channel decoding means 4A of the access point AP1 decodes the messages X _AU and X _BU by the above-described method (Maximum Ratio Combining) based on the decoded one message X _RU (step S15). Thus, a series of operations is completed.

As described above, in the second embodiment, the wireless device A transmits a message _{X AU,} the bit sequence _{X A} consisting of the parity check bits _{X AC} message _{X AU,} the wireless device B, the message _{X BU} If the message to send the _{X BU} parity check bits _{X BC} and the bit sequence _{X B} consisting of wireless device R, the parity check bits X of the message _{X RU} consisting exclusive OR of the message _{X AU} and message _{X BU} send a bit sequence _{X R} consisting of _RC, the access point AP1, the bit sequence _{X a,} X B, the received signal _s a of _{X R,} s B, based on the _{s R,} decodes the message _{X RU} by the above-described method and, the method described above using one message _{X RU} that the decoded (Maximal ATiO the Combining) by decrypting the message _{X AU,} the _{X BU.}

That is, the access point AP1 decodes the messages X _AU and X _BU using one message X _RU decoded based on the received signals s _A , s _B and s _R.

  Accordingly, communication reliability can be improved.

The radio apparatus R is a relay device transmits only the parity check bits X _RC to the access point AP1.

  Therefore, communication can be made efficient.

[Embodiment 3]
FIG. 11 is a schematic diagram showing the configuration of the radio apparatuses A, B, and R shown in FIG. 1 according to the third embodiment. The wireless device A shown in FIG. 1 includes the wireless device A-2 shown in FIG. 11 in the third embodiment.

  The wireless device A-2 is obtained by replacing the channel coding unit 2 of the wireless device A shown in FIG. 2 with the channel coding unit 2B and replacing the channel decoding unit 4 with the channel decoding unit 4B. The same.

If the wireless device A-2 is a wireless device R, channel coding section 2B receives the message _{X RU} from adding circuit 6, the received message _{X RU} calculates Π the _{(X RU)} to the message _{X RU} Interleave.

Thereafter, the channel coding means 2B calculates Γ (Π (X _RU )) using the same channel coding method as the channel coding means 2. This Γ (Π (X _RU )) represents the parity check bit of the interleaved message X _RU .

Then, the channel coding means 2B modulates the signal ψ _R (t) composed of Π (X _RU ) and Γ (Π (X _RU )) using the equation (2), and the modulated signal ψ _R (t ) To the access point AP1.

When the wireless device A-2 is the wireless device A or the wireless device B, the channel coding unit 2B performs channel coding of the message X _AU or the message X _BU by the same method as the channel coding unit 2 to the access point AP1. Send.

The channel decoding means 4B uses a logarithmic likelihood from the received signal s _A of the message X _AU transmitted from the wireless device _A and the received signal s _B of the message X _BU transmitted from the wireless device B using equation (4). The degree ratios L _A and L _B are calculated.

Then, the channel decoding means 4B substitutes the calculated log likelihood ratios L _A and L _B into the equation (13), and the log likelihood ratio for the bit sequence X _R = [X _RU , X _RC ] of the message X _RU. L ′ _R = [L ′ _RU , L ′ _RC ] is calculated.

Further, the channel decoding unit 4B receives the signal s _RU corresponding to Π (X _RU ) from the radio apparatus R, substitutes the received signal s _RU for the equation (4), and uses the log likelihood ratio L _RU. Is calculated.

Then, the channel decoding unit 4B deinterleaves the log likelihood ratio L _RU to calculate Π ^-1 (L _RU ), and the calculated Π ^-1 (L _RU ) and the log likelihood ratio L ' _R = The total value L ″ _RU is calculated by substituting the log likelihood ratio L ′ _{RU of} [L ′ _RU , L ′ _RC ] into the following equation.

Then, the channel decoding unit 4B calculates the received signal s ′ _RU by substituting the total value L ″ _RU into L ′ _R (t) in the equation (14), and the log likelihood ratio L ′ _R = [L ′ _RU. , L and _RC 'are substituted into _R (t) received signal s' L of the formula (14) calculates the _{RC 'RC]} log likelihood ratio L' of the received signal _{s 'R = [s' RU} , s ' _RC ]

Thereafter, the channel decoding means 4B, based on the received signal s _RC corresponding to Γ (Π (X _RU )) from the radio apparatus R and the received signal s ′ _R = [s ′ _RU , s ′ _RC ], The message X _RU is decoded by the decoding method in the second embodiment, and the message X _AU and X _BU are decoded by the decoding method (Maximum Ratio Combining) in the first embodiment using the decoded one message X _RU. To do.

  Note that the access point AP1 shown in FIG. 1 also has the same configuration as that of the wireless device A-2 shown in FIG. 11 in the third embodiment.

  FIG. 12 is a schematic diagram showing the configuration of the decoding circuit held by the channel decoding means 4B shown in FIG. The channel decoding means 4B holds the decoding circuit 70 shown in FIG. Decoding circuit 70 includes arithmetic circuits 71 to 74, deinterleave circuits 75, 80, 81, SISO decoders 77, 79, interleave circuit 78, and determiner 82.

Calculation circuit 71 substitutes the _s i (t) calculates the log likelihood ratios _{L A} of the received signal _{s A} of the formula (4) the received signal _{s A,} calculating the calculated log likelihood ratios _{L A} Output to the circuit 73.

Calculation circuit 72 substitutes the _s i (t) calculates the log likelihood ratio _{L B} of the received signal _{s B} of formula (4) the received signal _{s B,} calculating the calculated log likelihood ratio _{L B} Output to the circuit 73.

The arithmetic circuit 73 calculates the log likelihood ratio L ′ _R = [L ′ _RU , L ′ _RC ] according to the equation (13) based on the log likelihood ratio L _A and the log likelihood ratio L _B. outputs log likelihood ratio L _'R = [L' _RU, L and the operation of the _{RU 'RC]} log likelihood ratio L' of the adder 76, the log likelihood ratio L _'R = [L' _RU, The log likelihood ratio L ′ _RC of L ′ _RC ] is output to L _{c of the} SISO decoder 77.

The arithmetic circuit 74 substitutes the received signal s _R for s _i (t) in the equation (4) to calculate the log likelihood ratio L _R = [L _RU , L _RC ] of the received signal s _R and performs the calculation. log likelihood ratio _{L R = [L RU, L} RC] outputs the log likelihood ratio _{L RU} to de-interleave circuit 75, the log likelihood ratio _{L R = [L RU, L} RC] log likelihood ratio L and outputs the _RC to _{L c} of the SISO decoder 79.

Deinterleave circuit 75 deinterleaves the log likelihood ratio _{L RU} calculates the Π ^-1 _{(L RU),} and outputs ^-1 [pi was the operation of the _{(L RU)} to the adder 76.

The adder 76 substitutes the log likelihood ratio L ′ _RU and Π ⁻¹ (L _RU ) into the equation (15) to calculate the total value L ″ _RU, and calculates the calculated total value L ″ _RU to the SISO decoder. and outputs it to the 77 of the _{L c.}

The SISO decoder 77 calculates the log likelihood ratio / L _RU by the same method as the SISO decoder 41 based on the log likelihood ratios L ″ _RU , L ′ _RC and the output signal of the deinterleave circuit 80. The calculated log likelihood ratio / L _RU is output to the interleave circuit 78.

Interleave circuit 78 interleaves the LLR _{/ L RU,} and outputs the interleaved log likelihood ratio _{/ L RU} to SISO decoder 79.

SISO decoder 79, an output of the interleaving circuit 78, based on the log likelihood ratio _{L RC} from the arithmetic circuit 74 calculates the _{L e} and _{L SOVA,} and outputs the calculated _{L e} to de-interleave circuit 80 , L _SOVA = / L _RU is output to the deinterleave circuit 81.

Deinterleave circuit 80 deinterleaves the _{L e,} and outputs the de-interleaved _{L e} to SISO decoder 77.

Deinterleave circuit _81, L SOVA = _/ a _{L RU} deinterleaves, and outputs the de-interleaved _L SOVA = _{/ L RU} to determiner 82.

The determiner 82 receives the deinterleaved L _SOVA = / L _RU from the deinterleave circuit 81, determines the received L _SOVA = / L _RU to bit “1” or bit “0”, and outputs the message X _RU To do.

Thus, the channel decoding means 4B decodes the message _XRU using the decoding circuit 70 shown in FIG. 12 based on the received signals s _A , s _B and s _R.

And since the channel decoding means 4B was able to correctly decode only one message X _RU among the messages X _AU , X _BU , and X _RU , the channel decoding means 4B is implemented based on the one message X _RU that has been correctly decoded. The messages X _AU and X _BU are decoded using the Maximum Ratio Combining described in the first embodiment.

That is, the channel decoding means 4B outputs a message _{X RU} to the channel coding unit 3 receives a bit sequence _{X R} message _{X RU} from the channel coding unit 3. Then, the channel decoding unit 4B decodes the messages X _AU and X _BU by the method described above based on the log likelihood ratios L _A and L _B and the bit sequence X _R.

In the third embodiment, the wireless device R is repeater, since a [pi interleaved message _{X RU (X RU),} Π and _{(X RU)} gamma was channel coding _{(Π (X RU))} Since the following bit sequence X _R = [Π (X _RU ), Γ (Ｘ (X _RU ))] is transmitted to the access point AP1, wireless communication can be performed using an existing wireless LAN protocol. .

FIG. 13 is a flowchart for explaining the decoding method according to the third embodiment. When a series of operations is started, the access point AP1 receives the received signals s _A , s _B , and s _R of the messages X _AU , X _BU , and X _RU from the wireless devices A, B, and R, respectively (step S21). . In this case, the received signal s _A is a received signal of a signal composed of a message X _AU and a parity check bit X _AC of the message X _AU , and the received signal s _B is a parity check bit X of the message X _BU and the message X _BU. is the received signal of the signal consisting of _BC, the received signal _{s R} is composed of a [pi interleaved message _{X RU (X RU),} Π and parity check bits _{(X RU) Γ (Π (} X RU)) This is a received signal.

Then, channel decoding means 4B access point AP1, the received signal _{s A,} s B, _s each of _R log-likelihood ratios _{L A,} L B, calculates the _{L R} (step S22).

Thereafter, the channel decoding unit 4B of the access point AP1 calculates the log likelihood ratio L ′ _R = [L ′ _RU , L ′ _RC ] by substituting the log likelihood ratios L _A and L _B into the equation (13). (Step S23).

Subsequently, the channel decoding means 4B of the access point AP1 is deinterleaves the _{L RU} LLR _{L R} calculates a Π ^-1 _{(L RU)} (Step S24).

Then, channel decoding means 4B of the access point AP1, the operation of the overall value _{L "RU} of [pi ^-1 and _{(L RU)} log likelihood ratio _{L 'R = [L' RU} , L and _{RU 'RC]} L of' (Step S25).

Then, the channel decoding means 4B of the access point AP1 decodes the message _XRU by the method described above based on the log likelihood ratios L ″ _RU , L ′ _RC , L _RC (step S26).

Thereafter, the channel decoding means 4B of the access point AP1 decodes the messages X _AU and X _BU by the above-described method (Maximum Ratio Combining) based on the decoded one message X _RU (step S27). Thus, a series of operations is completed.

As described above, in the third embodiment, the wireless device A transmits a message _{X AU,} the bit sequence _{X A} consisting of the parity check bits _{X AC} message _{X AU,} the wireless device B, the message _{X BU} Then, the wireless device R transmits the bit sequence X _B composed of the parity check bit X _BC of the message X _BU , and the wireless device R interleaves the message X _RU composed of exclusive OR of the message X _AU and the message X _BU ( send a _{X RU), Π (X RU} ) parity check bits gamma of _{(Π (X RU))} consisting of the bit sequence _{X R = [Π (X RU} ), Γ (Π (X RU))] and, the access point AP1, the bit sequence _{X a,} X B, the received signal _s a of _{X R,} s B, based on the _{s R,} the above-described method Te decrypts the message _{X RU,} decodes message _{X AU,} the _{X BU} by the above-described method (Maximal Ratio Combining) using one message _{X RU} that the decoding.

That is, the access point AP1 decodes the messages X _AU and X _BU using one message X _RU decoded based on the received signals s _A , s _B and s _R.

  Accordingly, communication reliability can be improved.

The radio device R is repeater, a [pi interleaved message _{X RU (X RU), Π} (X RU) Γ was channel coding _{(Π (X RU))} consisting of the bit sequence _X R = [ Since Π (X _RU ), Γ (Π (X _RU ))] is transmitted to the access point AP1, wireless communication can be performed using an existing wireless LAN protocol.

  In the above description, the method of improving the reliability of communication in the case where the wireless devices A and B transmit a message to the access point AP1, that is, in the uplink, has been described. In the embodiment of the present invention, Not limited to this, in the downlink, the reliability of communication may be improved by any one of the above-described first to third embodiments. In this case, the wireless network includes the wireless network 20 shown in FIG. FIG. 14 is a schematic diagram of another wireless network according to the embodiment of the present invention.

  The wireless network 20 includes access points AP1 and AP2 and wireless devices A and R.

  In the wireless network 20, the access points AP 1 and AP 2 correspond to the wireless devices A and B of the wireless network 10, respectively, and the wireless device A corresponds to the access point AP 1 of the wireless network 10.

Accordingly, the wireless device A receives the received signals s _A , s _B , and s _R from the access points AP 1 and AP 2 and the wireless device R, respectively, and based on the received received signals s _A , s _B , and s _R , The messages X _AU and X _BU respectively transmitted from the access points AP1 and AP2 are decoded by the method of any one of the first to third embodiments.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

  The present invention is applied to a wireless network capable of improving communication reliability.

1 is a schematic diagram of a wireless network according to an embodiment of the present invention. FIG. 2 is a schematic block diagram illustrating a configuration of the wireless device illustrated in FIG. 1 according to the first embodiment. It is a circuit block diagram which shows the structure of the channel coding means shown in FIG. It is a figure for demonstrating the method of a channel decoding process. It is the schematic which shows the structure of the decoding circuit which the channel decoding means shown in FIG. 2 hold | maintains. FIG. 6 is a diagram for explaining a decoding method in the SISO decoder shown in FIG. 5. 5 is a flowchart for explaining a decoding method according to the first embodiment. FIG. 3 is a schematic block diagram illustrating a configuration of a wireless device illustrated in FIG. 1 in a second embodiment. It is the schematic which shows the structure of the decoding circuit which the channel decoding means shown in FIG. 8 hold | maintains. 12 is a flowchart for illustrating a decoding method according to the second embodiment. FIG. 6 is a schematic diagram illustrating a configuration of a wireless device illustrated in FIG. 1 in a third embodiment. It is the schematic which shows the structure of the decoding circuit which the channel decoding means shown in FIG. 11 hold | maintains. 12 is a flowchart for explaining a decoding method according to the third embodiment. It is the schematic of the other radio | wireless network by embodiment of this invention.

Explanation of symbols

  1 antenna, 2, 2A, 2B, 3 channel coding means, 4, 4A, 4B channel decoding means, 5 error checking circuit, 6 additional circuit, 7 message receiving means, 8 message generating means, 10, 20 wireless network, 21, 24, 44, 45 arithmetic unit, 22, 23 delay unit, 25 connection circuit, 26 modulation circuit, 40, 50 decoding circuit, 41-43, 55, 57, 77, 79 SISO decoder, 46, 47, 60, 82 determination 51, 54, 71-74 arithmetic circuit, 56, 78 interleave circuit, 58, 59, 75, 80, 81 deinterleave circuit, 76 adder, A, B, R wireless device, AP1, AP2 access point.

Claims (5)

A first wireless device;
A second wireless device;
A first parity check bit that is a parity check bit of the first message is calculated, and the calculated first parity check bit is added to the first message to generate a first packet. A third wireless device for transmitting the first packet to the first and second wireless devices;
A second parity check bit that is a parity check bit of the second message is calculated, and the calculated second parity check bit is added to the second message to generate a second packet. And a fourth wireless device that transmits the second packet to the first and second wireless devices,
The second wireless device receives the first and second packets, decodes the first and second messages based on the received first and second packets, and receives the decoded first And calculating the exclusive OR of the second message and generating a third message, calculating a third parity check bit which is a parity check bit of the third message, and calculating the calculated third Adding a parity check bit to the third message to generate a third packet, and transmitting the generated third packet to the first wireless device;
The first wireless device receives the first to third packets, performs a decoding process on the first to third messages based on the received first to third packets, When only one message among the first to third messages can be correctly decoded, one of the two messages that could not be correctly decoded is indicated by using the one message that has been correctly decoded. A log likelihood ratio is calculated, and the calculated log likelihood ratio is subjected to a channel decoding process for returning a parity check bit to the original information to correctly decode the one message. An exclusive OR operation with one message is calculated to correctly decode the other message of the two messages, and all of the first to third messages can be correctly decoded. The first to third log likelihood ratios are calculated based on the first to third received signals that are received signals of the first to third packets, and the calculated first log likelihood is calculated. A fourth log likelihood ratio indicating the second message is calculated based on the ratio and the third log likelihood ratio, and the second log likelihood ratio and the third log likelihood ratio are calculated. A fifth log-likelihood ratio indicating the first message is calculated based on the first log-likelihood ratio and the fifth log-likelihood ratio as inputs, and the channel decoding process is performed to input the first log-likelihood ratio and the fifth log-likelihood ratio. A process of calculating the second log likelihood ratio by calculating the log likelihood ratio of 1 and performing the channel decoding process with the second log likelihood ratio and the fourth log likelihood ratio as inputs Is repeatedly executed a predetermined number of times to correctly decode the first and second messages. A first wireless device;
A second wireless device;
A first parity check bit that is a parity check bit of the first message is calculated, and the calculated first parity check bit is added to the first message to generate a first packet. A third wireless device for transmitting the first packet to the first and second wireless devices;
A second parity check bit that is a parity check bit of the second message is calculated, and the calculated second parity check bit is added to the second message to generate a second packet. And a fourth wireless device that transmits the second packet to the first and second wireless devices,
The second wireless device receives the first and second packets, decodes the first and second messages based on the received first and second packets, and receives the decoded first The third message is generated by calculating the exclusive OR of the second message and the second message, and the third message is interleaved and the parity check bit of the third message subjected to the interleaving. Calculating a third parity check bit, generating a third packet comprising the calculated third parity check bit, and transmitting the generated third packet to the first wireless device;
The first wireless device receives the first to third packets, and indicates the third message from the first and second received signals that are received signals of the first and second packets. A log likelihood ratio of 1 is calculated, a second log likelihood ratio indicating a third parity check bit is calculated from the received signal when the third packet is directly received, and the calculated first and second A third log likelihood indicating one of the first and second messages using the third message decoded correctly based on a log-likelihood ratio of 2; The degree ratio is calculated, and the third log likelihood ratio is subjected to a channel decoding process for returning the parity check bit to the original information to correctly decode the one message, and the third message and the One message Chromatography and calculates the exclusive OR of the di-and the other message decoding correctly the two messages, the wireless network. A first wireless device;
A second wireless device;
A first parity check bit that is a parity check bit of the first message is calculated, and the calculated first parity check bit is added to the first message to generate a first packet. A third wireless device for transmitting the first packet to the first and second wireless devices;
A second parity check bit that is a parity check bit of the second message is calculated, and the calculated second parity check bit is added to the second message to generate a second packet. And a fourth wireless device that transmits the second packet to the first and second wireless devices,
The second wireless device receives the first and second packets, decodes the first and second messages based on the received first and second packets, and receives the decoded first The third message is generated by calculating the exclusive OR of the second message and the second message, and the third message is interleaved and the parity check bit of the third message subjected to the interleaving. A third parity check bit is calculated, the calculated third parity check bit is added to the interleaved third message to generate a third packet, and the generated third packet is added to the first packet. To the wireless device
The first wireless device receives the first to third packets, and indicates the third message from the first and second received signals that are received signals of the first and second packets. 1 calculates the log-likelihood ratio, the third packet calculates a second log likelihood ratio showing the third message from the received signal when it receives directly, a second logarithmic likelihood that the calculated The third log likelihood ratio is calculated by deinterleaving the frequency ratio, the fourth log likelihood ratio is calculated by calculating the sum of the calculated first and third log likelihood ratios, and the calculation is performed. decoding the third message based on the fifth log likelihood ratio showing the third parity-check bits and the fourth log likelihood ratio, by using the third message can be decrypted that correctly, wherein the first and sixth showing one of the messages of the second message Calculates the number likelihood ratio, it performs a channel decoding process of returning the parity check bits to the original information correctly decode the one message to the sixth log likelihood ratio which is the operation, the third message A wireless network that calculates an exclusive OR of the one message and correctly decodes the other message of the two messages.   The wireless network according to claim 1, wherein the first wireless device is an access point.   The wireless network according to any one of claims 1 to 3, wherein each of the third and fourth wireless devices is an access point.

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