KR20140142643A - Method of controlling interference in a multi-hop network based on mimo system and a relay node and node pair enabling the method - Google Patents
Method of controlling interference in a multi-hop network based on mimo system and a relay node and node pair enabling the method Download PDFInfo
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- H04B7/14—Relay systems
- H04B7/15—Active relay systems
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Abstract
A relay node and a node pair using an interference control method and an interference control method in a multi-hop network based on a MIMO system are disclosed. A method of controlling interference in a multi-hop network according to an exemplary embodiment of the present invention is a method for relaying a signal received from source nodes among node pairs in a relay node to destination nodes in a pair with the source nodes, So that at least some of the interference signals between the two or more node pairs can be removed. Also, in the node pairs, the residual interference signal among the interference signals between two or more node pairs can be removed using the signal received from the destination nodes.
Description
The following embodiments relate to a relay node and a node pair using an interference control method and an interference control method in a multi-hop network based on a MIMO system.
Until now, communication systems have been used mainly as means for connecting people and people. Therefore, only about 1% of the devices currently on the planet are connected to each other by the network. However, due to the development of communication technology and the unification trend due to the integration of devices, various devices including smart phones, sensor devices and other communication functions constitute a huge network. In addition, users of many communication terminals are making easier use of various applications such as content sharing, synchronization, output, and games through direct connection between devices. There are wireless access technologies that can support device-to-device (D2D) communication beyond cellular communication using existing infra-structure to respond to the market demand change.
Although the initial D2D communication scheme is a transmission scheme that assumes a single hop, future D2D communication seems to utilize multi-hop. In addition, the relay technique to date has used a plurality of relay nodes to obtain a diversity gain or a multiplexing gain assuming that there is one source node and one destination node. In the future, it is expected that a plurality of node pairs transmit signals at a time, such as a multi-unicast multi-hop network. Accordingly, research is continuing to control interference between a plurality of node pairs and a plurality of relay nodes.
A method of controlling interference in a multi-hop network according to an exemplary embodiment is a method for controlling interference between two or more relay nodes and a pair of nodes in a multi-hop network, the method comprising: ) Relaying a signal received from nodes to destination nodes that are paired with the source nodes and adjusting a channel coefficient of the relay nodes so that interference signals between the two or more node pairs Removing at least some of the interference signals; And removing, in the node pairs, a residual interference signal among the interference signals between the two or more node pairs using a signal received at the destination nodes.
The steps may be performed during the signal transmission between the relay nodes and the node pairs.
Wherein removing the at least some interfering signal comprises: generating an effective interfering channel matrix corresponding to the at least some interfering signal based on interfering channel matrices between the source nodes and the destination nodes; Generating a reference matrix representing a null space of the effective interfering channel matrix by adjusting the channel coefficient; And removing the at least some of the interference signals using the effective interference channel matrix and the reference matrix.
Wherein the step of generating the effective interfering channel matrix comprises the steps of: generating a first channel matrix corresponding to an interference signal of at least a portion of a first interfering signal between the source nodes and the relay nodes, Obtaining a second channel matrix corresponding to at least a portion of the interfering signal of the second interfering signal; And generating the effective interfering channel matrix based on the first channel matrix and the second channel matrix.
Wherein generating the effective interfering channel matrix comprises: transposing the first channel matrix; And computing a Kronecker product of the second channel matrix and the transposed first channel matrix.
The reference matrix may be included in the null space of the effective interfering channel matrix and may include a plurality of null space vectors excluding a zero vector.
The number of relay nodes may be less than the number of relay nodes designed to remove the entire interference signal between the node pairs.
The signal transmission process may be performed using either a time division scheme or a frequency division scheme.
The source node or the destination node may be a multiple-input multiple-output (MIMO) scheme, and may further include removing an internal interference signal between two or more antennas included in each of the node pairs .
Wherein the step of removing the inner interference signal comprises the steps of: when a full-channel state information at transmitter (Full-CSIT) exists between the source nodes and the destination nodes, Forcing Beamforming: ZFBF) technique to remove the internal interference signal of the node pairs.
Wherein the step of removing the internal interference signal comprises the steps of: when no channel information is present between the source nodes and the destination nodes (No-Channel State Information at transmitter: No-CSIT) And removing the internal interference signal using a Successive Interference Cancellation (SIC) technique based on a part of the signals received by the nodes.
The removing of the residual interference signal may include removing the residual interference signal based on a part of the signals received by the destination nodes in the other signal transmission process.
The number of signal transmission processes may be equal to or greater than the number of the signals.
When there are two relay nodes, the steps may be performed in the first signal transmission process to the third signal transmission process.
Wherein the step of removing the at least a part of the interference signal comprises the step of transmitting, in the first signal transmission process, an interference signal included in the second destination node from any one antenna included in the first source node among the interference signals between the node pairs Removing remaining interference signals except an interference signal transmitted to one antenna; The method of
In the third signal transmission process, the relay node transmits an interference signal transmitted from one of the antennas included in the first source node to one of the antennas included in the second destination node in the first signal transmission process Signal from the first source node and transmits the same signal as an interference signal transmitted from one of the antennas included in the second source node to one of the antennas included in the first destination node in the second signal transmission process From the second source node.
In the third transmission process, the removing the residual interference signal may include removing the residual interference signal based on a part of the signals received by the destination nodes in the first transmission process and the second transmission process .
According to another aspect of the present invention, there is provided a method of controlling interference between two or more relay nodes and a pair of nodes in a multi-hop network, the method comprising: and relaying the real component signal and the imaginary component signal received from the source nodes to the destination nodes that are paired with the source nodes by adjusting the channel coefficient of the relay nodes, Removing at least some of the interference signals among the pair of nodes; And removing, in the node pairs, a residual interference signal among the interference signals between the two or more node pairs using at least one of the real component signal and the imaginary component signal received at the destination nodes .
The steps may be performed during the signal transmission between the relay nodes and the node pairs.
A method of controlling interference of a relay node in a multi-hop network according to an embodiment includes receiving signals from source ones of the pair of nodes; And relaying the received signal to destination nodes that are paired with the source nodes, wherein the channel coefficient of the relay node is adjusted so that at least a part of the interference signals between the two or more node pairs And removing the interference signal of the signal.
The steps may be performed during the signal transmission between the relay nodes and the node pairs.
A method of controlling interference of two or more node pairs in a multi-hop network according to an exemplary embodiment of the present invention includes: transmitting signals from source nodes of the source node pairs to the destination nodes through relay nodes; And removing residual interference signals among the interference signals between the two or more node pairs using signals received at the destination nodes.
The steps may be performed during the signal transmission between the relay nodes and the node pairs.
FIG. 1 illustrates a multi-hop network and alternating topology according to an exemplary embodiment of the present invention. Referring to FIG.
FIG. 2 is a diagram for explaining a multi-hop network based on a MIMO system according to an embodiment.
3 is a diagram for explaining the cancellation of at least a part of the interference signal among the interference signals between the node pairs according to the embodiment.
FIGS. 4A and 4B are diagrams for illustrating removal of a residual interference signal among interference signals between node pairs when there is no transmission channel information according to an exemplary embodiment.
FIG. 5 is a diagram for explaining the removal of a residual interference signal among interference signals between node pairs when all transmission channel information according to an exemplary embodiment exists.
6 is a view for explaining a method of controlling interference in a multi-hop network in an SISO system according to an embodiment.
7 is a flowchart illustrating an interference control method in a multi-hop network according to an exemplary embodiment of the present invention.
8 is a flowchart illustrating an interference control method in a multi-hop network in an SISO system according to an exemplary embodiment of the present invention.
Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to or limited by the embodiments. In addition, the same reference numerals shown in the drawings denote the same members.
<Multi-hop network and Alternating Topology >
FIG. 1 illustrates a multi-hop network and alternating topology according to an exemplary embodiment of the present invention. Referring to FIG.
Referring to FIG. 1, a
Specifically, in the
In the time slot k,
[Equation 1]
&Quot; (2) "
here,
An interference control scheme in a multi-hop network according to an exemplary embodiment can control interference in a multi-hop network using cooperation between relay nodes and node pairs. Relay nodes may create an alternating topology such as
For example, in the
< MIMO System-based multi-hop network>
FIG. 2 is a diagram for explaining a multi-hop network based on a MIMO system according to an embodiment.
Referring to FIG. 2, a multi-hop network based on a MIMO system according to an exemplary embodiment includes two or more source nodes, two or more relay nodes, and two or more destination nodes. For example, the network may comprise K source nodes, L relay nodes, and K destination nodes.
Hereinafter, for convenience of explanation, it is assumed that K is 2 and L is 2. Here, the source nodes include concurrent transmission nodes using the same frequency, and the relay nodes may include cooperative relay nodes operating in half-duplex.
The source node and the destination node each include at least two antennas, and each relay node may include at least one antenna. For example, both the source terminal and the destination terminal may include M antennas, and the i-th relay terminal may include N i antennas.
The source node may form a node pair with the destination node. Hereinafter, it is assumed that the first source node S 1 tries to transmit data to the first destination node D 1 and the second source node S 2 tries to transmit data to the second destination node D 2 . In this case, the first source node S 1 and the first destination node D 1 form a pair, and the second source node S 2 and the second destination node D 2 form a pair.
The first source node S 1 may transmit data to the first destination node D 1 through two relay nodes. And the second source node S 2 can transmit data to the second destination node D 2 through the two relay nodes.
A channel between a plurality of antennas included in each of the source nodes and at least one antenna included in each of the relay nodes may be represented by a first channel matrix H as a first hop channel. For example, referring to equation (3), the first channel matrix H
&Quot; (3) "
The received signal vector received by the i < th > relay node through the first hop channel is given by Equation (4).
&Quot; (4) "
here,
The i < th >
&Quot; (5) "
here,
Meanwhile, a channel between a plurality of antennas included in each of the at least one antenna and each of the destination nodes included in each of the relay nodes may be expressed as a second channel matrix G as a second-hop channel have. For example, referring to equation (6), the second channel matrix G
&Quot; (6) "
The received signal vector received by the j-th destination node via the second hop channel is given by Equation (7).
&Quot; (7) "
here,
Hereinafter, inter-user interference and intra-user interference between node pairs in a MIMO-based multi-hop network according to an exemplary embodiment will be described in detail.
< MIMO In a system-based multi-hop network, Pair Interference cancellation technique>
3 is a diagram for explaining the cancellation of at least a part of the interference signal among the interference signals between the node pairs according to the embodiment.
Referring to FIG. 3, the relay node can relay the signal received from the source node among the node pairs to the destination nodes that are paired with the source nodes. At this time, the relay node can remove the interference of at least part of the interference signals between two or more node pairs through an interference neutralization technique by adjusting the channel coefficient.
In one embodiment, the relay node uses a relay beamforming matrix in which the first hop channel and the second hop channel are simultaneously considered, so that the signal transmitted from the remaining source nodes other than the source node in which the destination node is paired with the corresponding destination node It is possible to prevent interference with the signal. In this case, the relay node may perform linear beamforming.
Depending on the number of relay nodes, the interference signal between the node pairs may be eliminated altogether, at least partly. The number of relay nodes may be smaller than the number of relay nodes designed to eliminate the entire interference signal between the node pairs. In the interference neutralization scheme, the number of relay nodes that can eliminate the entire interference signal between the node pairs is
(1) When the number of relay nodes is L? K (K-1) +1
Number of relay nodes
&Quot; (8) "
Where x i is the symbol transmitted by the ith source node. Also, h ij is the MIMO channel from the j-th source node to the i-th relay node, and g ij is the MIMO channel from the j-th relay terminal to the i-th destination terminal. w i is a beamforming matrix of the i-th relay terminal and can be generated by adjusting the channel coefficient.
In Equation (8)
In this case, all but w i can be given environmental values. For example, a relay node may know values other than wi by receiving feedback from a base station or the like. The relay node may use w i to make the entire effective channel a block diagonal matrix.
The condition for eliminating the interference between the node pairs can be expressed as Equation (9).
&Quot; (9) "
g 11 w 1 h 12 + g 12 w 2 h 21 + g 13 w 3 h 32 = 0 MxM
g 21 w 1 h 11 + g 22 w 2 h 21 + g 23 w 3 h 31 = 0 MxM
Equation 10 is the Kronecker product < RTI ID = 0.0 >
&Quot; (10) "
Here, vec (X) is an operation for vectorizing a matrix called X. For example, if the size of the matrix X is mxn, the magnitude of the vector vec (X) is mn x 1. Equation (9) can be modified as shown in Equation (11) according to Equation (10).
&Quot; (11) "
here,
The plurality of linear equations included in Equation (11) can be expressed in a matrix form of Equation (12).
&Quot; (12) "
At this time, the solution satisfying the expression (12) can be expressed by the expression (13). Since the matrix T is not a square matrix,
&Quot; (13) "
Here, null (A) is a null space of the matrix A. The null space of matrix A may be the set of all vectors y satisfying Ay = 0. Therefore, the relay node calculates the relay node < RTI ID = 0.0 >
(2) When the number of relay nodes is L < K (K-1) +1
The number of relay nodes
&Quot; (14) "
Where x i is the symbol transmitted by the ith source node. Also, h ij is a MIMO channel from a j-th source node to an i-th relay node, and g ij is a MIMO channel from a j-th relay terminal to an i-th destination terminal. w i is a beamforming matrix of the i-th relay terminal and can be generated by adjusting the channel coefficient.
The condition for eliminating interference between node pairs can be expressed as shown in Equation (15) and Equation (15) can be modified as shown in Equation (16) according to the Kronacker product operation.
&Quot; (15) "
g 11 w 1 h 12 + g 12 w 2 h 21 = 0 MxM
g 21 w 1 h 11 + g 22 w 2 h 21 = 0 MxM
&Quot; (16) "
here,
The plurality of linear equations included in Equation (16) can be expressed in a matrix form of Equation (17).
&Quot; (17) "
In this case, since the effective interference channel matrix T is a square matrix,
In one embodiment, the node pair and the relay node can remove the interfering signal and the interfering signal between the node pairs by transmitting a signal over the first to third transmission steps. (a), (b), and (c) illustrate an example of an interference cancellation technique for eliminating at least some interference signals among interference signals between node pairs. The number of source antennas included in the source node and the number of destination antennas included in the destination node may be M. An antenna included in a first node pair may be represented by 1 to M, and an antenna included in a second node pair may be represented by M + 1 to 2M.
(a) shows a step (first transmission step) of allowing only the interference signal from the
The first transmission step to the third transmission step may be performed using either the time division method or the frequency division method. When the first to third transmission steps are performed using the time division scheme, each transmission step may correspond to each time slot. When the first to third transmission steps are performed using the frequency division scheme, each transmission step may correspond to each frequency band. In one embodiment, the number of transmission steps may be equal to or greater than the number of signals that the source node transmits to the destination node that is a pair with the source node.
(a) shows a first transmission step. Each antenna of the first source node transmits signals a 1 through a M , and each antenna of the second source node can transmit signals b 1 through b M. In order to remove at least some of the interference signals between the node pairs, the relay node only allows the interference signal from the
&Quot; (18) "
Here, h ij denotes a MIMO channel from the jth antenna to the i-th relay node included in the source node, and represents a first channel matrix corresponding to at least a part of the interference signal between the source nodes and the relay nodes. Expressed in equation (18)
(b) shows a second transmission step. Each antenna of the first source node may transmit signals a M + 1 through a 2M and each antenna of the second source node may transmit signals b M +1 through b 2M . In order to remove at least some of the interference signals between the node pairs, the relay node only allows the interference signal from the antenna M + 1 included in the second source node to the
&Quot; (19) "
(b), only the interference signal from the antenna M + 1 included in the second source node to the
(c) shows a third transmission step. Each antenna of the first source node transmits signals a 1 , a 2 M +1 through a 3 M -1 and each antenna of the second source node transmits signals b M +1, b 2 M + 1 through b 3 M -1 Lt; / RTI > In order to eliminate at least some of the interference signals of the interference signals between the node pairs, the relay node transmits an interference signal from
&Quot; (20) "
In the third transmission step of (c), the relay node transmits an interference signal transmitted from one of the antennas included in the first source node to one of the antennas included in the second destination node in the first transmission step , a 1 ) from the first source node, and in a second transmission step, an interference signal (a 1) transmitted from one of the antennas included in the second source node to one of the antennas included in the first destination node For example, b M +1 ) from the second source node.
Only the interference signal from the
< No - CSIT Internal interference in the environment and node Pair Residual interference cancellation technique>
FIGS. 4A and 4B are diagrams for explaining the removal of the residual interference signal among the interference signals between the node pairs when there is no transmission channel information according to an embodiment (No-CSIT (Channel State Information at Transmitter) environment) to be.
Referring to FIG. 4A, in the No-CSIT environment, internal interference between node pairs can be removed by applying a Successive Interference Cancellation (SIC) technique to a destination node. In the example of FIGS. 4A and 4B, the serial interference cancellation technique is a technique in which the number of signals received at each antenna of a destination node and the number of equations of a destination are equal to each other, The number of antennas of the node must be the same.
(a) shows a technique of eliminating internal interference and residual interference between node pairs in the first transmission step of FIG. (a), each of the M antennas of the first destination node receives M signals (e.g., signals a 1 to a M ) including M-1 interference signals from M antennas of the first source node can do. The serial interference cancellation technique is applied to the first destination node, so that the first destination node can extract the signals a 1 to a M. Accordingly, the internal interference between the node pairs at the first destination node can be eliminated.
Each of the antennas M + 2 to 2M of the second destination node can receive M signals including M-1 interference signals from M antennas of the second source node. The antenna M + 1 of the second destination node receives M signals (e.g., signals b 1 to b M ) from the M antennas of the second source node and receives one interference Signal (e.g., signal a 1 ). Since the second destination node receives M + 1 signals, the number of signals received by each antenna of the second destination node and the number of antennas of the second destination node may be different. Therefore, the serial interference cancellation technique can not be applied to the second destination node of (a).
(b) shows the inner interference and residual interference cancellation technique between the node pairs in the second transmission step of FIG. (b), each of
Each of the M antennas of the second destination node may receive M signals (e.g., signals b M +1 through b 2M ) containing M-1 interfering signals from the M antennas of the second source node . Therefore, the serial interference cancellation technique is applied to the second destination node, and the second destination node can extract signals b m +1 through b 2M . Accordingly, the internal interference between the node pairs at the first destination node can be eliminated.
(c) shows a technique of eliminating internal interference and residual interference between node pairs in the third transmission step of FIG. (c), the antenna M + 1 of the second destination node receives M signals (e.g., signals a 1 , a 2M + 1 to a 3M -1 ) from the M antennas of the second source node , One interfering signal (e.g., signal b M + 1 ) from
Referring to FIG. 4B, (d) shows a residual interference cancellation technique of the first node pair in the second transmission step of FIG. 4A. (d),
(e) shows a residual interference cancellation technique of the second node pair in the first transmission step of FIG. 4A. (e), the antenna M + 1 of the second destination node receives M signals (e.g., signals b 1 to b M ) from the M antennas of the second source node, 1 (for example, signal a 1) one of the interference signals from the can receive. Since the second destination node receives M + 1 signals, the number of signals received by each antenna of the second destination node and the number of antennas of the second destination node may be different from each other. Therefore, The serial interference cancellation technique can not be applied to the destination node. In order to apply the serial interference cancellation technique to the second destination node of (e), the second destination node may exclude the signal a 1 extracted in the third transmission step of (c) from the application of the serial interference cancellation technique . The signal a 1 is excluded from the application, so that the number of variables and the number of equations to be applied to the serial interference cancellation technique become equal. Accordingly, the serial interference cancellation technique is applied to the second destination node, so that the second destination node can extract the signal L 4 (a 1 , b 1 ), the signal b 2 to the signal b M. Here, the signal L 4 (a 1 , b 1 ) may mean an equation in which the signal a 1 and the signal b 1 are linearly combined. By applying the serial interference cancellation technique to the second destination node, the internal interference between the node pairs of the second destination node can be eliminated. The second destination node may signal a 1 by applying the extract in a third transmission step of (c) to the signal L 4 (a 1, b 1 ), extracts the signal b 1. The second antenna M + 1 by the signal b 1 a 1 and the interference signal is received to extract the destination node, whereby the residual interference between the node pair in the first transmission stage may be removed.
In the first transmission step and the second transmission step, each of the first source node and the second source node can transmit M signals, which are not interference signals. In the third transmission step, the first source node and the second source node can transmit M-1, respectively. In the first to third transmission steps, each of the first destination mode and the second destination node can receive 3M signals including one interfering signal and extract 3M-1 signals. For each transmission step, each node pair can obtain Degrees of Freedom (DoF), and the node pairs
< Full - CSIT Internal interference in the environment and node Pair Residual interference cancellation technique>
FIG. 5 is a diagram for explaining the removal of a residual interference signal among interference signals between node pairs when all transmission channel information according to an embodiment exists (Full-CSIT environment).
Referring to FIG. 5, in a full-CSIT environment, internal interference between node pairs can be removed by applying a Zero-Forcing Beamforming (ZFBF) technique to a source node.
(a) and (b) illustrate a technique of eliminating residual interference between node pairs and internal interference in the first transmission step of FIG. (a), each of the M antennas of the first source node transmits M signals (e.g., signals a 1 to a M ) including M-1 interference signals to M antennas of the first destination node . At this time,
(c) and (d) illustrate a technique for eliminating internal interference and residual interference between node pairs in the second transmission step of FIG. (c), each of the M antennas of the first source node transmits M signals (e.g., signals a M +1 through a 2M ) including M-1 interference signals to M antennas of the first destination node, Can be transmitted. Each of the M antennas of the second source node can transmit M signals (e.g., signals b M +1 through b 2M ) including M-1 interfering signals to M antennas of the second destination node . At this time, antenna M + 1 of the second source node can transmit one interference signal (e.g., signal b M +1 ) to
(e) and (f) show a residual interference cancellation technique between the internal interference and the node pairs in the third transmission step of FIG. (e), each of the M antennas of the first source node transmits M signals (e.g., signals a 1 , a 2 M +1 to signal A 1 , a 2 M +1) including M-1 interference signals to M antennas of the first destination node a 3M -1 ), and
A first destination node can be extracted by applying the first signal a first extraction step in the transmitted signal to L 3 (a 1, b M +1), M +1 signal b. The second destination node can extract the signal a 1 by applying b M +1 extracted in the second transmission step to the signal L 4 (a 1 , b M +1 ). A first antenna being the first antenna M + 1 is the interference signal received a1 extraction of the received interference signal b M +1 and the second destination node, the destination node, the residual interference between the node pair in the third transfer step, it is removed .
In the first transfer step, the second destination node may extract the third by applying the interference signals a 1 extracted from the transmission step to the first signal L 1 (a 1, b 1) of the transfer phase, the signal b 1. The second antenna M + 1 by the signal b 1 a 1 and the interference signal is received to extract the destination node, whereby the residual interference between the node pair in the first transmission stage may be removed.
In the second transmission step, the first destination node applies the interference signal b M + 1 extracted in the third transmission step to the signal L 2 (a M +1 , b M +1 ) in the second transmission step to generate the signal b M +1 can be extracted. Since the signal a M + 1 and the
For each transfer phase, each node pair can acquire Degrees of Freedom (DoF), and the node pairs
For the sake of convenience, the interference control technique in the above-described multi-hop network is only for the case where the number of node pairs is 2 and the number of relay nodes is 2, but the present invention is not limited thereto. For example, when the number of node pairs is 3, the number of relay nodes is 6, so that interference control techniques in a multi-hop network can be performed.
< SISO Interference control using signal separation in a system-based multi-hop network>
6 is a view for explaining a method of controlling interference in a multi-hop network in an SISO system according to an embodiment.
Referring to FIG. 6, in a single input single output (SISO) system, a relay node can relay a signal received from a source node among node pairs to destination nodes that are paired with source nodes. The source node can separate the signal into a real component signal and an imaginary component signal and transmit it to the destination node that is paired with the source node. The relay node may relay the real component signal and the imaginary component signal to the destination nodes that are paired with the source nodes. In one embodiment, the channel matrix from the source node to the relay node may appear as, which may correspond to a channel matrix from the source node to the relay node with two antennas in a MIMO system. Therefore, when the SISO system separates the signal into the real component signal and the imaginary component signal, the interference cancellation technique between the node pairs in the multi-hop network and the residual interference cancellation technique between the internal interference and the node pairs, Lt; / RTI >
In one embodiment, when the number of node pairs is two and the number of relay nodes is two, the relay node may adjust channel coefficients to remove at least some of the interference signals among the node pairs. The destination node may remove the residual interference signal among the interference signals between the two or more node pairs using at least one of a real component signal and an imaginary component signal received by the relay node. For example, the node pair and the relay node can transmit signals through the first transmission step to the third transmission step.
(a) shows a first transmission step. In the first transmission step, the first source node transmits the real component signal a R1 and the imaginary component signal a I1 , and the second source node can transmit the real component signal b R1 and the imaginary component signal b I1 . In order to remove at least some of the interference signals among the node pairs, the relay node adjusts the channel coefficient to allow only the transmission of the real component signal a R1 of the first source node to the second destination node, Can be removed.
(b) shows a second transmission step. In the second transmission step, the first source node transmits the real component signal a R2 and the imaginary component signal a I2 , and the second source node can transmit the real component signal b R2 and the imaginary component signal b I2 . To remove at least some of the interfering signals of the interfering signals between the node pairs, the relay node adjusts the channel coefficients to only allow the transmission of the real component signal b R2 of the second source node to the first destination node, Can be removed.
(c) shows a third transmission step. In the third transmission step, the first source node transmits the real component signal a R1 and the imaginary component signal a I3 , and the second source node can transmit the real component signal b R2 and the imaginary component signal b I3 . In order to remove at least some of the interfering signals of the interfering signals between the node pairs, the relay node adjusts the channel coefficient so that the transmission of the real component signal a R1 of the first source node to the second destination node and the transmission of the real component Only the transmission of the signal b R2 to the first destination node is allowed, and the remaining interference signals can be removed.
In a no-CSIT environment, internal interference between node pairs can be eliminated by applying a serial interference cancellation technique to the destination node. In the first transmission step, the first destination node can extract the real component signal a R1 and the imaginary component signal a I1 by removing internal interference between the first node pair using the serial interference cancellation technique.
In the second transmission step, the second destination node can extract the real component signal a R2 and the imaginary component signal a I2 by removing the internal interference between the second node pairs using the serial interference cancellation technique.
In the third transmission step, the first destination node excludes the real component signal a R1 extracted in the first transmission step from the application of the serial interference cancellation technique, and outputs the signal L 1 (a R1 , b R2 ) and the imaginary component signal a I3 And the second destination node extracts the signal L 2 (a R1 , b R2 ) and the imaginary component signal b I3 by excluding the real component signal b R2 extracted in the second transmission step from the application of the serial interference cancellation technique. can do. By applying the serial interference cancellation technique to the first destination node and the second destination node, the internal interference between the node pairs at the first destination node and the second destination node can be eliminated. A first destination node may extract a real component signal b R2 by applying the real component signal a R1 extracted from the first transfer step to the signal L 1 (a R1, b R2 ). The second destination node may extract a real component signal R1 by applying the real component signal b R2 extracted in the second transmitting step the second signal L (R1 a, R2 b). The interference signal b R2 received by the first destination node and the interference signal a R1 received by the second destination node are extracted so that the residual interference signal between the node pairs can be removed in the third transmission step.
In the second transmission step, a first destination node, the signals L 3, by removing the inner interference between a first node pair and excluded from the subject of the real component signal b R2 an interference cancellation technique derived from three transmission steps (a R2 , b R2 ) and the imaginary component signal a I2 can be extracted. The first destination node can extract the signal a R2 by applying the real component signal b R2 extracted in the third transmission step to the signal L 3 (a R2 , b R2 ). The signal a R2 received by the first destination node And the interference signal b R2 are extracted, the residual interference between the node pairs in the second transmission step can be eliminated.
In the first transmission step, the second destination node removes the real component signal a R1 extracted in the third transmission step from the application of the serial interference cancellation technique, thereby removing the internal interference between the second node pairs, thereby generating the signal L 4 (a R1 , b R1 and imaginary component signal b I1 can be extracted. The second destination node can extract the signal b R1 by applying the real component signal a R1 extracted in the third transmission step to the signal L 4 (a R1 , b R1 ). The signal b R1 received by the second destination node And the interference signal a R1 are extracted, the residual interference between the node pairs in the first transmission step can be eliminated.
In the full-CSIT environment, the internal interference between the node pairs can be removed using a zero-forcing beamforming technique at the source node. In the first transmission step, a zero forcing beamforming technique is applied to the first source node and the second source node, so that the internal interference between the node pairs can be eliminated. The internal interference between the node pairs is eliminated, so that the first destination node can extract the signal a R1 and the signal a I1 , and the second destination node can extract the signal b I1 from L 1 (a R1 , b R1 ) .
In the second transmission step, a zero forcing beamforming technique is applied to the first source node and the second source node to eliminate internal interference between the node pairs, so that the first destination node transmits the signals L 2 (a R 2 , b R 2 ) a it is possible to extract the I2, the second destination node can extract a signal b and R2 b signal I2.
In the third transmission step, the zero forcing beamforming technique is applied to the first source node and the second source node to eliminate internal interference between the node pairs, so that the first destination node transmits the signal L 3 (a R1 , b R2 ) a it is possible to extract the I3, the second destination node may extract the L 4 (R1 a, R2 b) and the signal b I3. A first destination node may extract a real component signal b R2 by applying the real component signal a R1 extracted from the first transfer step to the signal L 3 (R1 a, R2 b). The second destination node may extract a real component signal R1 by applying the real component signal b R2 extracted in the second transfer step to a signal L 4 (R1 a, R2 b). The interference signal b R2 received by the first destination node and the interference signal a R1 received by the second destination node are extracted so that the residual interference signal between the node pairs can be removed in the third transmission step.
In the second transmission step, the first destination node can extract the signal a R2 by applying the real component signal b R2 extracted in the third transmission step to the signal L 2 (a R2 , b R2 ). The signal a R2 received by the first destination node And the interference signal b R2 are extracted, the residual interference between the node pairs in the second transmission step can be eliminated.
In the first transmission step, the second destination node can extract the signal b R1 by applying the real component signal a R1 extracted in the third transmission step to the signal L 1 (a R1 , b R1 ). The signal b R1 received by the second destination node And the interference signal a R1 are extracted, the residual interference between the node pairs in the first transmission step can be eliminated.
In the No-CSIT environment and the Full-CSIT environment, through the first to third transmission steps, the first destination node and the second destination node receive the DoF (5/3)
<Interference Control Method in Multi-hop Network>
7 is a flowchart illustrating an interference control method in a multi-hop network according to an exemplary embodiment of the present invention.
Referring to FIG. 7, in an interference control method in a multi-hop network according to an exemplary embodiment, in a relay node, a signal received from source nodes among node pairs is relayed to destination nodes that are paired with source nodes, At least some of the interference signals between the two or more node pairs may be removed (710) by adjusting the channel coefficients of the relay nodes.
Also, in an interference control method in a multi-hop network according to an embodiment, residual interference signals among the interference signals between the two or more node pairs can be removed using signals received from the destination nodes in the node pairs 720).
8 is a flowchart illustrating an interference control method in a multi-hop network in an SISO system according to an exemplary embodiment of the present invention.
Referring to FIG. 8, in an interference control method in a multi-hop network in an SISO system according to an embodiment, in a relay node, a real component signal and an imaginary component signal received from source nodes of node pairs are transmitted to source nodes (810) at least some of the interference signals between the two or more node pairs by removing the interfering signals of the two or more node pairs by controlling the channel coefficients of the relay nodes.
In addition, the interference control method in a multi-hop network in a SISO system according to an exemplary embodiment uses at least one of a real component signal and an imaginary component signal received at destination nodes in an interference pair, The remaining interfering signals of the signal may be removed (820).
The interference control method in the multi-hop network according to the embodiment shown in FIG. 7 and the interference control method in the multi-hop network in the SISO system according to the embodiment shown in FIG. The contents may be applied as they are, so that detailed description is omitted.
The method according to an embodiment may be implemented in the form of a program command that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions to be recorded on the medium may be those specially designed and configured for the embodiments or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.
While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. For example, it is to be understood that the techniques described may be performed in a different order than the described methods, and / or that components of the described systems, structures, devices, circuits, Lt; / RTI > or equivalents, even if it is replaced or replaced.
Therefore, other implementations, other embodiments, and equivalents to the claims are also within the scope of the following claims.
Claims (20)
Wherein the relay node relays signals received from source nodes of the node pairs to destination nodes that are paired with the source nodes, Coefficient to remove at least some of the interference signals between the two or more node pairs; And
Removing, in the node pairs, a residual interference signal among the interference signals between the two or more node pairs using a signal received at the destination nodes
Lt; / RTI >
Wherein the steps are performed in the signal transmission process between the relay nodes and the node pairs,
A method for controlling interference in a multi - hop network.
Wherein the removing the at least some of the interference signals comprises:
Generating an effective interfering channel matrix corresponding to the at least some interfering signal based on interfering channel matrices between the source nodes and the destination nodes;
Generating a reference matrix representing a null space of the effective interfering channel matrix by adjusting the channel coefficient; And
Removing the at least a portion of the interference signal using the effective interference channel matrix and the reference matrix
Hop network in a multi-hop network.
Wherein generating the effective interfering channel matrix comprises:
A first channel matrix corresponding to an interference signal of at least a part of the first interference signal between the source nodes and the relay nodes and a second channel matrix corresponding to an interference signal of at least a part of the second interference signal between the relay nodes and the destination nodes Acquiring a second channel matrix to be transmitted; And
Generating the effective interfering channel matrix based on the first channel matrix and the second channel matrix
Hop network in a multi-hop network.
Wherein generating the effective interfering channel matrix comprises:
Transposing the first channel matrix; And
Computing a Kronecker product of the second channel matrix and the transposed first channel matrix;
Hop network in a multi-hop network.
Wherein the reference matrix comprises:
And a plurality of null space vectors included in the null space of the effective interfering channel matrix except for a zero vector.
Wherein the number of relay nodes
Wherein the number of relay nodes is less than the number of relay nodes designed to remove the entire interference signal between the node pairs.
The signal transmission process includes:
A method for controlling interference in a multi-hop network, the method being implemented using either a time division scheme or a frequency division scheme.
The source node or the destination node may be a multiple-input multiple-output (MIMO)
Removing an internal interference signal between two or more antennas included in each of the node pairs
Further comprising the steps of:
Wherein the removing the internal interference signal comprises:
When there is full-channel state information at transmitter (Full-CSIT) between the source nodes and the destination nodes, the ZFBF Removing the inner interference signal of the node pairs,
A method for controlling interference in a multi - hop network.
Wherein the removing the internal interference signal comprises:
When there is no transmission channel information between the source nodes and the destination nodes (No-Channel State Information at transmitter: No-CSIT), a part of the signals received by the destination nodes As a basis, the step of removing the inner interference signal using Successive Interference Cancellation (SIC)
A method for controlling interference in a multi - hop network.
The step of removing the residual interference signal comprises:
Removing the residual interference signal based on a part of the signals received by the destination nodes in another signal transmission process,
A method for controlling interference in a multi - hop network.
Wherein the number of the signal transmission processes includes:
Wherein the number of signals is equal to or greater than the number of the signals.
If there are two relay nodes,
Wherein the steps are performed in a first signal transmission process to a third signal transmission process,
A method for controlling interference in a multi - hop network.
Wherein the removing the at least some of the interference signals comprises:
The method of claim 1, wherein, in the first signal transmission step, the remaining interference, excluding an interference signal transmitted from one of the antennas included in the first source node to one of the antennas included in the second destination node among the interference signals between the node pairs, Removing the signal;
The method of claim 1, wherein, in the second signal transmission step, the interference signal transmitted from one of the antennas included in the second source node to one of the antennas included in the first destination node, among the interference signals between the node pairs, Removing the signal; And
The interference signal transmitted from one of the antennas included in the first source node to one of the antennas included in the second destination node among the interference signals between the node pairs in the third signal transmission process, Removing the remaining interference signals from any one of the antennas included in the source node except an interference signal transmitted to one of the antennas included in the first destination node;
Hop network in a multi-hop network.
In the third signal transmission process, the relay node
Receiving, from the first source node, a signal identical to an interference signal transmitted from one of the antennas included in the first source node to one of the antennas included in the second destination node in the first signal transmission process,
Receiving from the second source node a signal identical to an interference signal transmitted from one of the antennas included in the second source node to one of the antennas included in the first destination node in the second signal transmission process,
A method for controlling interference in a multi - hop network.
In the third transmission step, the step of removing the residual interference signal includes:
Wherein the residual interference signals are removed based on a part of the signals received by the destination nodes in the first transmission process and the second transmission process,
A method for controlling interference in a multi - hop network.
And relaying the real and imaginary component signals received from the source nodes of the node pairs to destination nodes that are paired with the source nodes at the relay nodes, Adjusting channel coefficients of the nodes to remove interference signals of at least some of the interference signals between the two or more node pairs; And
Removing at least one residual interference signal among the two or more node pairs using at least one of a real component signal and an imaginary component signal received at the destination nodes in the node pairs,
Lt; / RTI >
Wherein the steps are performed in the signal transmission process between the relay nodes and the node pairs,
A method for controlling interference in a multi - hop network.
Receiving signals from source ones of the node pairs; And
And relaying the received signal to destination nodes that are paired with the source nodes and adjusting a channel coefficient of the relay node so that at least some of the interference signals between the two or more node pairs The step of removing the interference signal
Lt; / RTI >
Wherein the steps are performed in the signal transmission process between the relay nodes and the node pairs,
A method for controlling interference of a relay node.
Transmitting a signal from the source nodes of the source node pairs to the destination nodes via relay nodes; And
Removing residual interference signals among the interference signals between the two or more node pairs using signals received at the destination nodes
Lt; / RTI >
Wherein the steps are performed in the signal transmission process between the relay nodes and the node pairs,
A method for controlling interference of a node pair.
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| JP2014114019A JP6506919B2 (en) | 2013-06-04 | 2014-06-02 | Interference control method in multi-hop network and relay node using the interference control method |
| US14/293,348 US9531449B2 (en) | 2013-06-04 | 2014-06-02 | Method of controlling interference in multi-hop network based on MIMO system and relay node and node pair using the method |
| EP14170907.1A EP2819315B1 (en) | 2013-06-04 | 2014-06-03 | Method of controlling interference in multi-hop network based on mimo system and relay node and node pair using the method |
| CN201410245145.8A CN104218980B (en) | 2013-06-04 | 2014-06-04 | Control the method for interference and relay node and node pair using this method |
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