WO2013073720A1 - Procédé de communication à relais dans un système avec plusieurs relais équipements utilisateur - Google Patents

Procédé de communication à relais dans un système avec plusieurs relais équipements utilisateur Download PDF

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WO2013073720A1
WO2013073720A1 PCT/KR2011/008718 KR2011008718W WO2013073720A1 WO 2013073720 A1 WO2013073720 A1 WO 2013073720A1 KR 2011008718 W KR2011008718 W KR 2011008718W WO 2013073720 A1 WO2013073720 A1 WO 2013073720A1
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Prior art keywords
node
relay
signal
channel
source
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PCT/KR2011/008718
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English (en)
Korean (ko)
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김동인
오경록
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성균관대학교 산학협력단
김진규
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Publication of WO2013073720A1 publication Critical patent/WO2013073720A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/14—Relay systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
    • H04L1/0076—Distributed coding, e.g. network coding, involving channel coding
    • H04L1/0077—Cooperative coding
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/14—Relay systems
    • H04B7/15—Active relay systems
    • H04B7/155—Ground-based stations
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W40/00—Communication routing or communication path finding
    • H04W40/02—Communication route or path selection, e.g. power-based or shortest path routing
    • H04W40/22—Communication route or path selection, e.g. power-based or shortest path routing using selective relaying for reaching a BTS [Base Transceiver Station] or an access point
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W40/00—Communication routing or communication path finding
    • H04W40/24—Connectivity information management, e.g. connectivity discovery or connectivity update
    • H04W40/246—Connectivity information discovery
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L2001/0092—Error control systems characterised by the topology of the transmission link
    • H04L2001/0097—Relays
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
    • H04W88/02—Terminal devices
    • H04W88/04—Terminal devices adapted for relaying to or from another terminal or user

Definitions

  • the disclosed technology relates to a relay communication method in a user equipment (hereinafter referred to as UE) relay system, and more particularly, but without limitation, relates to a method of performing relay communication by selecting an optimal relay among multiple UE relays. .
  • UE user equipment
  • the relay is introduced for the purpose of extending the service area for high speed data transmission and improving the transmission rate at the cell edge.
  • the UE relay refers to a general user equipment that plays a role of a relay.
  • Various communication terminals, including mobile communication terminals, have become widespread, and as the performance of such communication terminals improves, user terminals may perform functions of relays.
  • FIG. 1 is a diagram illustrating a decode-and-forward (DF) transmission model in a multi-terminal relay system.
  • Relay communication may be divided into a first phase (1 st phase) in which a source node transmits a signal and a second phase (2 nd phase) in which a relay node transmits a signal.
  • the source node (S) sends a signal at the same time to the relay node (R i) and a destination node (D).
  • h s, r1 , h s, r2 , h s, rN means a channel between the source node and each relay node
  • h s, d means a channel between the source node and the destination node.
  • the relay node decodes the signal received from the source node and retransmits it to the destination node.
  • h r1, d , h r2, d , h rN, d means a channel between each relay node and a destination node.
  • the destination node recovers the original signal by maximum ratio combining (MRC) the signals received from the source node and the relay node.
  • MRC maximum ratio combining
  • An object of the present disclosure is to provide a method for performing relay communication through an optimal relay node among a plurality of relay nodes.
  • relay nodes provide feedback information to a source node, so that the source node selects an optimal relay node.
  • the disclosed technology provides three transmission techniques for performing communication by selecting an optimal relay node in a wireless cooperative communication environment.
  • relay communication may be performed by selecting a method of maximizing an overall data rate among three transmission techniques.
  • a first aspect of the disclosed technology is a relay communication method in a multiple relay system, wherein a relay node transmits a signal transmitted from a destination node to a source node. Overhearing to determine a Relay-Destination (RD) channel grade; The relay node sending the R-D channel class to the source node; Selecting one of the relay nodes based on RD channel classes received by the source node from a plurality of relay nodes and source-relay (SR) channel information between the source node and the relay nodes; step; And the source node communicating with the destination node through the selected relay node.
  • RD Relay-Destination
  • a second aspect of the disclosed technology to achieve the above technical problem is a receiver for overhearing the signal transmitted by the destination node to the source node; A calculator for calculating a channel gain with the target node from the eavesdropping signal; A rating determiner configured to determine an R-D channel rating according to a section to which the channel gain belongs among channel gain sections divided into a plurality of threshold values; And a transmitter for transmitting the R-D channel class to the source node.
  • a third aspect of the disclosed technology includes: a receiver configured to receive relay-destination (R-D) channel class information from a plurality of relay nodes; A selector configured to select one of the relay nodes based on source-relay (S-R) channel information and the R-D channel class information with the relay nodes; And a transmitter for transmitting data to a target node through the selected relay node.
  • R-D relay-destination
  • S-R source-relay
  • a fourth aspect of the disclosed technology to achieve the above technical problem comprises the steps of selecting a relay node having a good connection state with the first target node and the second target node from the first relay node and the second relay node; Obtaining, by the source node, superimposed coding a signal to be transmitted to the first target node to obtain a first signal, and obtaining a second signal by overlapping the signal to be transmitted to the second target node; And transmitting, by the source node, the first signal and the second signal to the first and second destination nodes through the selected relay node, respectively.
  • a fifth aspect of the disclosed technology includes: selecting each connection from a source node to a first relay node as a first target node, and to a second relay node as a second target node; Obtaining, by the source node, superimposed coding a signal to be transmitted to the first target node to obtain a first signal, and obtaining a second signal by overlapping the signal to be transmitted to the second target node; And transmitting, by the source node, the first signal to the first relay node and the second signal to the second relay node.
  • the relay selected by the source node from the first relay node or the second relay node is an object selected from the first object node or the second object node. Selecting a node as the second relay; Obtaining, by the source node, superimposed coding a signal to be transmitted to the first target node to obtain a first signal, and obtaining a second signal by overlapping the signal to be transmitted to the second target node; And transmitting, by the source node, the first signal and the second signal to the first repeater and the second repeater.
  • a seventh aspect of the disclosed technology compares transmission rates according to three transmission techniques in a cooperative communication environment, and determines a method showing an optimal transmission rate as a transmission method and transmits according to the method. To provide.
  • Embodiments of the disclosed technology may have effects including the following advantages. However, since the embodiments of the disclosed technology are not meant to include all of them, the scope of the disclosed technology should not be understood as being limited thereto.
  • the SER performance is improved because communication can be performed by selecting an optimal relay in a multi-terminal relay system.
  • the disclosed technology provides the source node with the channel state information between the relay and the terminal with a small amount of information, and thus does not increase the system load.
  • relay communication may be performed by selecting a method of maximizing an overall data rate among a plurality of transmission techniques in advance.
  • FIG. 1 is a diagram illustrating a decode-and-forward (DF) transmission model in a multi-terminal relay system.
  • FIG. 2 is a diagram illustrating a multiple relay system according to an embodiment of the disclosed technology.
  • FIG. 3 is a flowchart illustrating a process of performing relay communication in the multiple relay system of FIG. 1.
  • FIG. 4 is a block diagram for describing in detail the source node 210 and the relay node 220 of FIG.
  • FIG. 5 is a graph showing the performance of the relay communication method of FIG.
  • FIG. 6 is a diagram illustrating a signal transmission method according to a first embodiment of three transmission schemes of the disclosed technology.
  • FIG. 7 is a diagram illustrating a signal transmission method according to a second embodiment of three transmission schemes of the disclosed technology.
  • FIG. 8 illustrates a signal transmission method according to a third embodiment of three transmission schemes of the disclosed technology.
  • FIG. 9 illustrates a simulation environment for comparing the effects of the first to third embodiments.
  • FIG. 10 is a graph showing a comparison between the simulation result of FIG. 9 and the transmission rate according to the conventional method.
  • first and second are intended to distinguish one component from another, and the scope of rights should not be limited by these terms.
  • first component may be named a second component, and similarly, the second component may also be named a first component.
  • each step may occur differently from the stated order unless the context clearly dictates the specific order. That is, each step may occur in the same order as specified, may be performed substantially simultaneously, or may be performed in the reverse order.
  • a source node 210 for generating a signal a source node 210 for generating a signal
  • a plurality of relay nodes 220 for transmitting a signal generated by the source node to a destination node and a source node are generated and transmitted. It includes a destination node 230 for receiving a signal.
  • the relay nodes 220 may be a Decode-and-Forward (DF) relay that decodes a signal received from the source node 210 and forwards it to the destination node.
  • DF Decode-and-Forward
  • the relay nodes 220 may all have different channel states from the target node 210 according to an environment, the relay nodes 220 select relays having an optimal channel state among the relay nodes 220 to perform relay communication. do.
  • the source node 210 needs to know the channel state of each relay node. However, if all relay nodes 220 feed back specific channel state information to source node 210, the load of the system may be increased. Accordingly, in the present embodiment, the relay nodes 220 feed back channel state information to the source node 210, but transmit the channel state information in a limited length, that is, a length of several bits. In FIG.
  • the relay nodes 220 divide the channel state information into three types, bad (BAD), good (GOOD), and good (BETTER) is provided to the source node 210.
  • the relay nodes 220 may compare their channel state with the thresholds and determine the channel grade as one of 0 (bad, BAD), 1 (good, GOOD), 2 (better, BETTER).
  • Each relay node of FIG. 2 is represented by a dotted line when the channel class is 0, a half dotted line when the channel class is 1, and a solid line when the channel class is 2.
  • K 1 is the number of relay nodes having a channel class of 1, which is 2 in the example of FIG. 1
  • K 2 is the number of relay nodes having a channel class of 2, which is 3 in the example of FIG. 1.
  • the source node 210 may select an optimal relay using the channel grade value fed back from the relay nodes 220. A detailed method of performing relay communication by the source node 210 selecting an optimal relay will be described with reference to FIG. 3.
  • FIG. 3 is a flowchart illustrating a process of performing relay communication in the multiple relay system of FIG. 2.
  • the source node 210 selects a relay node in consideration of the R-D channel gain and the S-R channel gain, and transmits data to the destination node 230 through the selected relay node.
  • step S310 the source node 220 transmits a signal to the surrounding relay nodes 220 and the destination node 230.
  • the destination node 230 transmits an ACK or NACK signal to the source node 220 in response to the signal transmitted from the source node 220.
  • the neighboring relay nodes 220 overhear the ACK / NACK signal transmitted from the destination node 230 to the source node 210 to determine a relay-destination (R-D) channel grade.
  • R-D relay-destination
  • the R-D channel grade may be determined according to the channel gain between each relay node 220 and the destination node 230.
  • An example in which the first relay nodes Relay-1 and 222 determine its own channel class will be described.
  • the first relay node 222 calculates a channel gain between the first relay node 222 and the destination node 230 from the intercepted signal.
  • the relay node 222 determines the RD channel grade according to the section to which the channel gain belongs among the sections divided into the plurality of threshold values.
  • the threshold values may be selected as values that minimize a symbol error rate (SER) according to a signal to noise ratio (SNR).
  • SNR signal to noise ratio
  • Equation 2 the probability of transmission error
  • k 1 is the channel gain
  • k 2 is the channel gain
  • the first term is a probability that a transmission error occurs in a first st phase where source-relay and direct-to-terminal direct transmissions occur.
  • the second term may cause an error in a second nd phase, in which a relay node 220 receiving a signal from a source node 210 transmits a signal to a terminal node 230. Means probability.
  • the channel grade is divided by 3 by using two threshold values, but the channel grade may be subdivided to more accurately reflect the RD channel gain.
  • the more detailed the channel grade the more the RD channel gain can be accurately reflected when selecting a relay.
  • the amount of information fed back to the source node 210 by the relay node 220 increases.
  • the channel grade information may be fed back to the source node 210 in 2-bit.
  • the first relay node 222 compares the calculated channel gain with the thresholds to determine the RD channel grade.
  • the first relay node 222 is a channel gain value smaller than the larger ⁇ th2 than ⁇ value th1, a first RD channel rating is determined as (Good, GOOD).
  • the relay nodes 220 transmit the determined RD channel grade to the source node 210.
  • the source node 210 may relay the nodes 220 based on the RD channel grades received from the plurality of relay nodes 220 and the SR channel information between the source node 210 and the relay nodes 220. Select one of the relay nodes. According to an embodiment, the source node 210 may select one relay node in the following manner.
  • the source node 210 selects a relay node having the highest SR channel state value among relay nodes having the same RD channel class for each RD channel class. That is, among k 1 relay nodes satisfying ⁇ th1 ⁇ ri, d ⁇ th2 , the SR link has the best value, for example, the relay node having the largest channel gain (hereinafter, R a ) and selects the channel.
  • the gain value is called ⁇ a .
  • select ⁇ th2 ⁇ ri, k 2 of the relay nodes from the SR link is the best value, for example, the largest RS channel gain (hereinafter, R b) satisfying the d and the channel gains It is called ⁇ b .
  • the source node 210 selects one relay node based on the RD channel class and the SR channel state value among the selected relay nodes for each RD channel class.
  • the source node 210 may select an optimal relay node by calculating a harmonic mean value of the RD channel state and the SR channel state. For example, as shown in Equation 5, the source node 210 selects a relay node having the largest harmonic mean value by comparing the result of the harmonic averaging of the RD channel gain and the SR channel gain ⁇ i with each other.
  • Equation 6 In the M-ary phase shift keying (M-PSK), the values of A, B, and r are shown in Equation 6.
  • P refers to the total power of the system
  • P 1 means the transmission power from the source node 210 to the relay node 220.
  • Equation 7 shows a result of calculating a harmonic mean for the selected relay nodes R a and R b .
  • a value corresponding to the RD channel gain uses an approximation value according to the RD channel class.
  • the RD channel gain may be determined as the minimum channel gain value of the corresponding RD channel class. That is, if the case of RD channel rating is 1, a ⁇ th1, the RD channel level 2, can be determined in a ⁇ th2.
  • the RD channel gain may be determined by a maximum channel gain value, an average maximum channel gain value, and the like of the corresponding RD channel grade interval.
  • the source node 210 selects the relay node having the largest harmonic mean value as the optimal relay node. do.
  • the source node 210 may transmit a signal to the destination node 230 through the selected relay node 220.
  • the source node 210 may inform the selected relay node 220 of the scheduling information before communicating with the target node 230 (S260) to enable proactive scheduling.
  • the source node communicates with the destination node 230 through the optimal relay node selected in operation S250.
  • FIG. 4 is a block diagram for describing in detail the source node 210 and the relay node 220 of FIG. Referring to FIG. 4, a process in which the source node 210 selects an optimal relay node 220 and transmits data through the selected relay node 220 will be described.
  • the source node 210 includes a receiver 410, a selector 420, and a transmitter 430.
  • the receiver 410 receives R-D channel class information from the plurality of relay nodes 220.
  • the selector 420 selects one of the relay nodes 220 based on the S-R channel information with the relay nodes 220 and the R-D channel class information received by the receiver 410.
  • the selector 420 may include a first selector 422 and a second selector 424.
  • the first selector 422 selects the relay node having the largest S-R channel gain value among the relay nodes having the same R-D channel class for each R-D channel class.
  • the second selector 424 selects a relay node having the largest harmonic mean value of the R-D channel grade value and the S-R channel gain value among the relay nodes selected by the first selector 422.
  • the second selector 424 provides the selected relay node information to the transmitter 430.
  • the transmitter 430 transmits data to the destination node through the selected relay node.
  • the transmitter 430 may provide scheduling information to the selected relay node in advance before transmitting data to the destination node 230.
  • the relay node 220 includes a receiver 440, a calculator 450, a rating determiner 460, and a transmitter 470.
  • the receiver 440 overhears the signal transmitted from the destination node 230 to the source node 210.
  • the calculator 450 calculates a channel gain with the destination node 230 from the intercepted signal.
  • the class determiner 460 determines an R-D channel class according to a section to which the calculated channel gain belongs among channel gain sections divided into a plurality of threshold values.
  • the rating determiner 460 may determine, as threshold values, a value that minimizes a symbol error rate (SER) according to a signal to noise ratio (SNR).
  • the transmitter 470 transmits the determined R-D channel class to the source node 210 so that the source node 210 can select an optimal relay.
  • SER symbol error rate
  • SNR signal to noise ratio
  • FIG. 5 is a graph showing the performance of the relay communication method of FIG. 5 is a graph comparing SER performance when transmitting 1-bit feedback information and transmitting 2-bit feedback information in the DF relay method.
  • the proposed 2-bit feedback shows better performance in both linear and nonlinear environments.
  • the graph of FIG. 4 is a result in a nonlinear environment, and it can be seen that a gain of about 1 dB is obtained compared to the existing 1-bit technique when two relays are used.
  • FIGS. 6 to 8 are diagrams for explaining three transmission schemes to which the relay communication method described in FIG. 3 may be applied in a cooperative communication environment.
  • the transmission scheme of FIGS. 6 to 8 selects an optimal relay when a plurality of relay nodes 220 and at least one destination node 230 exist, so that a signal can be transmitted using an optimal transmission scheme.
  • the transmission schemes described with reference to FIGS. 6 to 8 are transmission schemes based on partial signal transfer schemes, which are relayed by the relay node to the destination node using superposition coding and successive interference cancellation (SIC) techniques. Reduce the size of the signal and use it to reduce the transmission time. Therefore, according to the transmission scheme of FIGS. 6 to 8, it is possible to increase the overall transmission rate by a reduced time.
  • SIC superposition coding and successive interference cancellation
  • FIG. 6 is a diagram illustrating a signal transmission method according to a first embodiment of three transmission schemes of the disclosed technology.
  • the solid line represents the signal broadcast by the source node 610 in the first st phase
  • the dotted line represents the cooperative transmission through the relay node 620a in the second nd phase.
  • the source node 610 selects an optimal relay node 620a in consideration of a channel state among the plurality of relay nodes 620a and 620b, and selects two objects through the selected relay node 620a.
  • Signals are sent to nodes 630a and 630b.
  • a method of performing cooperative communication in the same manner as in FIG. 6 will be described in detail.
  • the source node 610 selects a relay node having a good channel state with the first target node 630a and the second target node 630b among the first relay node 620a and the second relay node 620b.
  • the source node 610 is the channel quality information (CQI) when the first relay node 620a is connected to the first target node 630a and the second target node 630b.
  • CQI channel quality information
  • the source node 610 selects a relay node is connected to the first destination node 630a and the second destination node 630b when the source node 610 selects the first relay node 620a.
  • the source node 610 selects the second relay node 620b, and calculates the transmission rate when the source node 610 is connected to the first target node 630a and the second target node 630b. Select the relay node with the higher rate.
  • the source node 610 may select the relay node through the same process as steps S310 to S350 of FIG. 3.
  • the destination nodes 630a and 630b respond to the source node (630).
  • the ACK / NACK signal is transmitted.
  • the relay nodes 620a and 620b listen to the signals transmitted by the destination nodes 630a and 630b to determine the R-D channel grades for the respective destination nodes 630a and 630b (S330).
  • the relay nodes 620a and 620b feed back the determined R-D channel grade to the source node 610 (S340).
  • the source node 610 selects an optimal relay node based on the RD channel grade fed back from the relay nodes 620a and 620b and the SD channel information between the source node 610 and the respective destination nodes 630a and 630b. (S350). For example, the source node 610 selects the relay nodes having the largest channel state value (ie, the harmonic mean of the channel gains) for all the destination nodes 630a and 630b, and selects the selected relay nodes. With respect to Equation 5, the relay having the highest average of the channel state values (ie, the harmonic mean of the channel gains) for each destination node can be selected.
  • the source node 610 assumes that the first relay node 620a is selected to proceed with the description.
  • the source node 610 obtains the first signal by superposition coding the signal to be transmitted to the first target node 630a, and superimposes the signal to be transmitted to the second target node 630b.
  • the first signal may be represented as in Equation 9
  • the second signal may be represented as in Equation 10.
  • ⁇ 1 , ⁇ 2 are power split coefficients, and have values of 0 ⁇ 1 ⁇ 0.5, 0 ⁇ 2 ⁇ 0.5, preferably 0 ⁇ 1 ⁇ 0.2, 0 ⁇ 2 ⁇ 0.2.
  • x b, 1 , x b, 2 are basic layer components transmitted directly from the source node 610 to the destination nodes 630a, 630b.
  • x sc, 1 , x sc, 2 are overlapping layer components transmitted through the first relay node 620a.
  • the subscript sc stands for superposed layer
  • the subscript b stands for basic layer.
  • the source node 610 transmits the first signal and the second signal to the first destination node 630a and the second destination node 630b through the first relay node 620a, respectively.
  • the source node 610 transmits the first signal and the second signal using different timeslots.
  • the first relay node 620a superimposes the overlapping layer components x sc, 1 , x sc, 2 of the first signal and the second signal received from the source node 610 again to overlap the first destination node 630a and the first signal. 2 is sent to the destination node 630b.
  • Overlapping coding at the first relay node 620a is performed in consideration of power splitting, which is represented by Equation (11).
  • ⁇ has a value of 0 ⁇ ⁇ ⁇ 1 as the power split coefficient, and preferably has a value of 0.5 ⁇ ⁇ 1.
  • the first target node 630a and the second target node 630b detect overlapping layer components of the first signal and the second signal from the received superimposed coded signal, respectively.
  • Both the first target node 630a and the second target node 630b detect x sc, 2 , and then the first target node 630a performs successive interference cancellation (SIC) to perform x sc. , 1 is detected.
  • SIC successive interference cancellation
  • a basic layer signal component is detected from the first signal and the second signal received from the source node 610. At this time, the basic layer signal is detected by the SIC.
  • the size of the signal transmitted from the relay node to the destination node can be reduced. By using this, it is possible to reduce the transmission time and increase the overall transmission rate by the reduced time.
  • the transmission rate according to the first embodiment is as follows. When the transmission rate according to the first embodiment is expressed by an equation, Equation 12 is obtained.
  • R b, 1 , R b, 2 is the transmission rate of the basic layer transmitted to each destination node (630a, 630b).
  • R sc, 1 and R sc, 2 are data rates of overlapping layers transmitted to respective destination nodes 630a and 630b.
  • R RD, 1 and R RD, 2 are transmission capacities formed between the selected first relay node 620a and each of the destination nodes 630a and 630b.
  • ⁇ is the Signal to Noise Ratio (SNR) at the instant each connection makes, and subscript 1 of ⁇ is the connection between the source node 610 and the selected first relay node 620a, 0. i is the connection between the source node 610 and the i-th destination node, subscript RD of ⁇ , 1 is the connection between the selected first relay node 620a and the first destination node 630a, and subscript RD, 2 is selected. Means a connection between the first relay node 620a and the second target node 630b.
  • ⁇ i and ⁇ are power split coefficients, and the value of ⁇ i is
  • the source node 710 selects an optimal relay node corresponding to each target node in consideration of a channel state of each of the plurality of relay nodes 720a and 720b. That is, in the first embodiment of FIG. 6, if one relay node 620a having an optimal channel state is selected with the first and second destination nodes 630a and 630b, in the second embodiment of FIG. One relay node having an optimal channel state is selected in the relationship with the node 730a, and one relay node having an optimal channel state is selected in the relationship with the second target node 730b. As a method of selecting a relay node, as described in FIG.
  • a method of selecting a relay node having a superior CQI, a method of describing a relay node having a higher transmission rate, or a process such as steps S310 to S350 of FIG. 3 may be performed.
  • a method of selecting a relay node having excellent channel state may be used.
  • the source node 710 may select a relay node having the harmonic mean value of the largest channel gain, respectively, for each of the destination nodes 630a and 630b.
  • the selected relay node is the first relay node 720a and the second relay node 720b, respectively.
  • the source node 710 obtains the first signal by overlapping the signal to be transmitted to the first destination node 730a, and overlaps the signal to be transmitted to the second destination node 730b to obtain the second signal.
  • the first signal is represented by Equation 9
  • the second signal is represented by Equation 10.
  • the source node 710 then transmits a first signal to the first relay node 720a and a second signal to the second relay node 720b. At this time, the source node 710 transmits the first signal and the second signal using different timeslots.
  • the first relay node 720a detects a basic layer component of the received first signal.
  • the second relay node 720b detects a basic layer component of the received second signal. Subsequently, the first relay node 720a detects an overlap layer component of the received first signal.
  • the second relay node 720b detects an overlap layer component of the received second signal. At this time, detection of the overlap layer component is performed by performing SIC at each relay node.
  • the above-described detection of the basic layer component and the overlapping layer component may be preceded by detection of the overlapping layer component by the SIC.
  • the first relay node 720a transmits the overlapping layer component of the detected first signal to the first destination node 730a.
  • the second relay node 720b transmits the overlapping layer component of the detected second signal to the second destination node 730b.
  • each relay node 720a and 720b transmits the detected overlapping layer components to the respective destination nodes 730a and 730b using the same timeslot.
  • the first target node 730a detects the overlapping layer component of the received first signal
  • the second target node 730b detects the overlapping layer component of the received second signal.
  • the overlapped layer component of the first signal and the overlapped layer component of the second signal may affect each other with noise.
  • the above-described second embodiment is a transmission method assuming that the first target node 730a and the second target node 730b are located at a far distance from each other, so that the noise effect is reduced by the path loss.
  • each destination node 730a, 730b can easily detect the overlap layer component sent to it.
  • the first target node 730a detects the basic layer component of the received first signal
  • the second target node 730b detects the basic layer component of the received second signal.
  • the basic layer component is detected by performing SIC.
  • the size of the signal transmitted from the relay node to the destination node can be reduced. By using this, it is possible to reduce the transmission time and increase the overall transmission rate by the reduced time. Meanwhile, the transmission rate according to the second embodiment is described below.
  • the transmission rate R tot, 2 according to the second embodiment may be calculated in the same manner as in Equation 12. However, R b, i , R sc, i , R RD, 1 , R RD, 2 are calculated as follows, unlike the case of the first embodiment.
  • the subscripts 1, i of ⁇ indicate a connection between the source node 710 and the i th relay node, and 0, i means a connection between the source node 710 and the i th destination node.
  • the subscript RD, 11 of ⁇ is a connection between the first relay node 720a and the first destination node 730a
  • RD, 21 is a connection between the second relay node 720b and the first destination node 730a
  • RD, 12 denotes a connection between the first relay node 720a and the second target node 730b
  • RD, 22 denotes a connection between the second relay node 720b and the second target node 730b.
  • FIG. 8 is a diagram illustrating a signal transmission method according to a third embodiment of the disclosed technology.
  • one destination node selected from two destination nodes 830a and 830b serves as a relay and transmits a signal.
  • the source node 810 selects an optimal relay node 820a in consideration of a channel state among the plurality of relay nodes 820a and 820b, and selects an optimal relay node 820a through the selected relay node 820a.
  • the destination node which also acts as a relay, sends a signal to the remaining destination nodes.
  • a method of performing cooperative communication in the same manner as in FIG. 8 will be described in detail.
  • the source node 810 selects one relay node from the first relay node 820a or the second relay node 820b.
  • the selected relay node is referred to as the 'first relay'.
  • the first repeater selects one destination node from the first destination node 830a and the second destination node 830b.
  • One destination node selected from two destination nodes also serves as a relay.
  • the destination node selected as the relay role is referred to as the 'second relay'.
  • the source node 810 selects the first repeater among the plurality of relay nodes 820a and 820b.
  • a method of selecting the first relay a method of selecting a relay node having a superior CQI as described in FIG. 6, a method of describing a relay node having a higher transmission rate, or a process such as steps S310 to S350 of FIG. 3.
  • the source node 810 selects relay nodes having the largest channel state value as shown in Equation 8 for all the target nodes 830a and 830b, and selects each target node as shown in Equation 5 for the selected relay nodes.
  • the relay having the highest average of the calculated channel state values may be selected.
  • the selected relay node is the first relay node 820a.
  • the second repeater may be selected among the destination nodes 830a and 830b in a similar manner to selecting the first repeater. That is, for example, the CQI when the first repeater 820a is connected with the first target node 830a and the CQI when the first repeater 820a is connected with the second target node 830b are compared. Can select the excellent destination node as the second relay. As another example, the data rate is calculated when the first repeater 820a is connected with the first destination node 830a, and the data rate is calculated when the first repeater 820a is connected with the second destination node 830b. Thus, the destination node of the higher rate can be selected as the second relay. As another example, the first relay 820a may select the destination node having the largest channel gain value among the two destination nodes 830a and 830b. Hereinafter, it is assumed that the destination node selected as the second relay is the first destination node 830a.
  • the source node 810 superimposes a signal to be transmitted to the first target node 830a to obtain a first signal, and superimposes a signal to be transmitted to the second target node 830b to perform a second signal.
  • the first signal may be expressed as shown in Equation 9
  • the second signal may be expressed as shown in Equation 9 described above.
  • the source node 810 transmits the first signal and the second signal to the first repeater 820a and the second repeater 830a. At this time, the source node 810 transmits the first signal and the second signal using different timeslots.
  • the first repeater 820a detects a basic layer component from the received first signal and the second signal, and detects an overlapping layer component from the first signal and the second signal.
  • the overlap layer component is detected using the SIC.
  • the first repeater 820a performs power division of the overlapped layer components of the detected first signal and the second signal, and transmits a signal on which the overlapping coding is performed to the second repeater 830a.
  • the second repeater 830a detects a basic layer component of the first signal from the overlap coded signal received from the first repeater 820a, the first signal broadcast from the source node 810, and the second signal. Since the first destination node 830a has been selected as the second relay 820a, a basic layer component of the first signal to be transmitted is detected.
  • the second relay 830a is directed to the second destination node 830b.
  • the second repeater 830a detects the basic layer components of the second signal from the first and second signals broadcast from the source node 810.
  • the basic layer component of the second repeater 830a is detected using SIC.
  • the second relay 830a overlaps the first signal and the second signal from the overlapped coded signal received from the first repeater 820a, the first signal and the second signal broadcast from the source node 810, and Detect layer components.
  • the second repeater 830a detects an overlapping layer component of the first signal, which is a signal transmitted to it, and detects an overlapping layer component of the second signal to be transmitted to the second target node 830b through the SIC.
  • the second repeater 830a transmits the overlapping layer component of the previously detected second signal to the second destination node 830b.
  • the second destination node 830b detects the basic layer component of the second signal by performing SIC on the overlapping layer component of the second signal transmitted from the first repeater 820a.
  • the size of the signal transmitted from the repeater to the destination node can be reduced. By using this, it is possible to reduce the transmission time and increase the overall transmission rate by the reduced time. Meanwhile, the transmission rate according to the third embodiment is described below.
  • the transmission rate according to the third embodiment is expressed by the equation (13).
  • R RD, 1 (1) is a transmission rate when x sc, 1 is transmitted from the first repeater 820a to the second repeater 830a.
  • R RD, 1 (2) is a transmission rate when x sc, 2 is transmitted from the first repeater 820a to the second repeater 830a.
  • R DD, 12 is a transmission capacity formed between the remaining destination nodes 830b not selected as the second repeater in the second repeater 830a.
  • R b, i , R sc, i , R RD, 1 (1) , R RD, 1 (2) , R DD, 12 can be calculated as follows.
  • subscript 1 of ⁇ is the connection between the source node 810 and the first destination node 830a
  • subscript 2 is the connection between the source node 810 and the second destination node 830b
  • subscript RD , 1 is the connection between the first repeater 820a and the first destination node 830a
  • subscript RD, 2 is the connection between the first repeater 820a and the second destination node 830b
  • the subscript DD, 12 is two The connection between the target nodes 830b not selected as the second repeater in the first repeater 830a.
  • FIG. 9 illustrates a simulation environment for comparing the effects of the first to third embodiments.
  • a source node Base, base station
  • a first relay node Relay 1
  • a second relay node Relay 2
  • the first and second target nodes are located in a shadow area.
  • the distance between the source node, the first relay node, and the second relay node is assumed to be a normalized distance 1, and the path loss coefficient is set to 3 to execute the simulation. Since the positions of the first relay node and the second relay node have an arbitrary distribution, the transmission rates according to the first, second and third embodiments described above are calculated according to each situation, and the calculated transmission rates are calculated. It is desirable to determine a method showing the optimal transmission rate by comparing the two methods and to transmit the method according to the method.
  • FIG. 10 is a graph showing a comparison between the simulation result of FIG. 9 and the transmission rate according to the conventional method. Looking at the graph of Figure 10, it can be seen that the transmission rate according to an embodiment of the disclosed technology brings about a gain of about 2dB compared to the conventional method.

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  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
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Abstract

L'invention concerne un procédé de communication à relais dans un système avec plusieurs relais équipements utilisateur (ci-après, UE), et plus spécifiquement mais de façon non limitative, un procédé permettant d'exécuter une communication à relais en sélectionnant un relais optimal parmi plusieurs relais UE. Dans les modes de réalisation, un procédé de communication à relais dans un système avec plusieurs relais comprend les étapes suivantes : déterminer, par un nœud relais, une classe de canaux R-D (Relais-Destination) en interceptant un signal transmis depuis un nœud de destination jusqu'à un nœud source ; transmettre, par le nœud relais, la classe de canaux R-D au nœud source ; sélectionner, par le nœud source, l'un quelconque d'une pluralité de nœuds relais sur la base des classes de canaux R-D reçues à partir de la pluralité de nœuds relais et des informations de canal S-R (Source-Relais) entre le nœud source et la pluralité de nœuds relais ; et communiquer, par le nœud source, avec le nœud de destination par l'intermédiaire du nœud relais sélectionné.
PCT/KR2011/008718 2011-11-14 2011-11-15 Procédé de communication à relais dans un système avec plusieurs relais équipements utilisateur WO2013073720A1 (fr)

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CN105682096A (zh) * 2016-01-29 2016-06-15 福建师范大学 基于agv和信誉机制的物联网可信路由选择方法及系统
CN110087278A (zh) * 2019-03-11 2019-08-02 西安电子科技大学 一种具有协作干扰的无线携能协作网络中的安全传输方法
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Publication number Priority date Publication date Assignee Title
CN105682096A (zh) * 2016-01-29 2016-06-15 福建师范大学 基于agv和信誉机制的物联网可信路由选择方法及系统
CN110087278A (zh) * 2019-03-11 2019-08-02 西安电子科技大学 一种具有协作干扰的无线携能协作网络中的安全传输方法
CN110087278B (zh) * 2019-03-11 2022-03-15 西安电子科技大学 一种具有协作干扰的无线携能协作网络中的安全传输方法
KR20220013336A (ko) * 2020-07-24 2022-02-04 한밭대학교 산학협력단 협력 다중 접속된 전력선 통신망의 df 모드의 릴레이 선택 시스템 및 방법
KR102475217B1 (ko) 2020-07-24 2022-12-09 한밭대학교 산학협력단 협력 다중 접속된 전력선 통신망의 df 모드의 릴레이 선택 시스템 및 방법

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