WO2011132827A1

WO2011132827A1 - Apparatus and method for transmitting data in multi-antenna based multi-hop ad hoc network

Info

Publication number: WO2011132827A1
Application number: PCT/KR2010/006643
Authority: WO
Inventors: 박준상
Original assignee: 홍익대학교 산학협력단
Priority date: 2010-04-20
Filing date: 2010-09-29
Publication date: 2011-10-27
Also published as: KR101076962B1

Abstract

The present invention provides an apparatus and method for transmitting data in a multi-antenna based multi-hop ad hoc network, comprising: a transmission device including two or more antennas; a reception device including two or more antennas; and relay nodes for constituting a plurality of mutually independent data transmission paths between the transmission device and the reception device, each of the data transmission paths including a plurality of relay nodes, each of the relay nodes including two or more antennas, wherein: the transmission device transmits signals, obtained by performing a dirty paper coding on mutually different original signals, to relay nodes constructing each of the data transmission paths; each of the relay nodes transmits the signals, which has been transmitted from the transmission device, to a next relay node or the reception device at the same time as receiving the signals; and the reception device receives each signal from the last relay node of each of the data transmission paths, decodes the received signal, thereby detecting the original signal.

Description

Apparatus and method for data transmission in multi-antenna based multihop ad hoc network

The present invention relates to a data transmission apparatus and method for increasing data transmission in a multi-antenna-based multi-hop ad hoc network, and more particularly, to apply a dirty paper coding technique and a beamforming technique in a multi-antenna-based multi-hop ad hoc network. The present invention relates to a data transmission apparatus and a method capable of increasing the amount of data transmission.

Recently, in order to provide a multimedia service, research on a multiple antenna system (MIMO (Multiple Input Multiple Output)) capable of efficiently using a limited frequency is being actively conducted as the capacity of transmission data and the speed of data transmission are increased.

Such a multi-antenna system can transmit data using channels independent of each antenna to increase transmission reliability and transmission rate compared to a single antenna system without additional frequency or transmission power allocation. A multi-antenna system in a multi-user environment eliminates interference between users or antennas by using dirty paper coding, which is a nonlinear precoding scheme.

Dirty paper coding is an interference signal cancellation technique at the transmitting end so that the receiving end is not affected by the interference signal when the transmitting end knows the interference signal in the presence of an interference signal other than the noise signal in the channel. That is, assuming that signal A is a signal to be sent to user A, and signal B is a signal to be sent to user B, signal A is first processed from an appropriate association with signal B, such as noise (A '). ) Is added to signal B and sent to the channel. Receiving this signal, User B considers both the noise from the channel and the processed signal (A ') as noise in the original signal B and decodes it, and User A completely recovers signal A from the processed noise (A'). This is called dirty paper coding.

The DPC technology has been developed as a multi-input multi-output (MIMO) multi-antenna utilization technology in single-hop wireless networks such as cellular mobile telephone networks.

Meanwhile, in the current wireless network, single-hop wireless networks such as cellular or Wi-Fi dominate the mainstream, but next-generation wireless networks such as 4G, WiBro, and mesh are required to form multi-hop networks. I'm going. Therefore, there is an urgent need for a method of increasing data throughput in a multi-antenna-based multihop ad hoc network.

Disclosure of Invention The present invention is to overcome the above-described problems, and an object of the present invention is to solve the problem of data transmission in which a multi-antenna-based multi-hop ad hoc network applies a dirty paper coding technique and a beamforming technique to increase data transmission amount. To provide an apparatus and method.

According to an exemplary embodiment of the present invention, there is provided a transmission apparatus including two or more antennas; A receiving device including two or more antennas; And a relay node forming a plurality of data transmission paths independent of the transmitting device and the receiving device, wherein each data transmission path includes a plurality of relay nodes, and each of the relay nodes includes two or more antennas. The transmitting device transmits a signal obtained by performing dirty paper coating on different original signals to the relay nodes constituting the respective data transmission paths, and each relay node simultaneously receives the signal transmitted from the transmitting device. And transmitting to a next relay node or the receiving device, wherein the receiving device receives signals from the last relay node of each data transmission path, and decodes the received signal to detect the original signal. A data transmission apparatus in a hop ad hoc network is provided.

According to another aspect of the present invention, there is provided a method comprising: establishing a plurality of independent data transmission paths within a multi-hop ad hoc network; The transmitting device calculates a weight vector matrix for removing interference components between the antenna of the relay node or the antennas of the receiving device; Generating a transmission signal by applying dirty pattern coding to mutually different original signals to be transmitted through the plurality of data transmission paths; Transmitting the generated transmission signal to each relay node through a plurality of antennas; Each of the relay nodes receiving a transmission signal and calculating a weight vector for use in transmitting the received transmission signal to a subsequent terminal; And applying a beamforming to the received transmission signal using the calculated weight vector, and then transmitting the beamforming to a next terminal, thereby providing a data transmission method in a multi-antenna based multihop ad hoc network.

As in the present invention, when the dirty paper coding technique and the beamforming technique are applied to the multi-antenna-based multi-hop ad hoc network, the end-to-end throughput can be improved as compared to the existing multi-hop ad-hoc network under the same conditions. .

1 is a conceptual diagram of a general multi-antenna system.

2 is a diagram illustrating a multiple antenna system.

3 is a schematic structural diagram of a data transmission apparatus in a multi-antenna-based multihop ad hoc network according to an embodiment of the present invention.

4 is a conceptual diagram illustrating a method of transmitting multiple signals in a transmitting device.

5 is a diagram illustrating a process of receiving multiple signals from a relay node in a receiving apparatus.

FIG. 6 is a schematic configuration diagram of the transmitting apparatus shown in FIG. 3.

FIG. 7 is a schematic diagram of the relay node illustrated in FIG. 3.

8 is a schematic structural diagram of the receiving device shown in FIG. 3.

9 is a flowchart illustrating a data transmission method in a multi-antenna based multihop ad hoc network according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

In IEEE 802.11 series of communication standards called Local Area Network (LAN), each terminal (corresponding to 'node') and an access point (AP) agree to use the same frequency band. It is. As a result, the terminal (node) and the access point (AP) can mutually recognize each other as one network member, and from this point of time, data and control packets are exchanged. There are two modes in the IEEE 802.11 standard, one of which is 'Infrastructured Mode' which only allows communication between access point (AP) and normal node, and does not allow direct communication between each node. The other is an 'ad-hoc mode' method in which nodes exchange information with each other without an entity connected to a network backbone such as an access point (AP).

In the present invention, relay nodes serving as routers in an ad hoc wireless network, which is an autonomous wireless network in which wirelessly communicating nodes communicate with each other without an access point, are transmitted and received nodes. The present invention provides an optimal data transmission method for improving data transmission rate and an apparatus for implementing the same in an environment in which data is transmitted in a multi-hop manner.

1 is a conceptual diagram of a general multi-antenna system, and FIG. 2 is a diagram illustrating a multi-antenna system.

1 and 2, MIMO is a kind of intelligent antenna made by a combination of a plurality of antennas and a signal processing device, and the intelligent antennas are mounted at both ends of communicating with each other as shown in FIG. Generally refers. As described above, in the MIMO environment, since a plurality of antennas are installed at both ends, a relationship between a plurality of signals simultaneously transmitted, received, and transmitted and the received signals is expressed by Equation (1) below.

[Equation 1]

y (k) = Hx (k) + n (k)

Where x is a transmitted signal vector, y is a received signal vector, n is a noise vector, and H is a matrix representing a channel between two nodes. (k represents time.) If we can find H in advance and ignore n, we can get x sent from y. The MIMO antenna can be modeled in various forms. In the present invention, the MIMO antenna is modeled as a linear time-invariant system.

In the MIMO environment, there is a signal processing device. The performance and the function vary depending on which algorithm is used in the signal processing devices of both ends. Therefore, the MIMO model considering the signal processing device is required for the development of the MIMO algorithm. Is shown.

If the model shown in Figure 1 is formulated, it can be represented by the following equation (2).

[Equation 2]

y (k) = VHUx (k) + Vn (k)

That is, the signal vector y received at time k is the product of the matrix V representing the signal processing method of the sender, the channel matrix H, and the U representing the signal processing method of the receiver, and the original signal x (assuming that noise n is ignored). .

In this case, t and r represent the number of antennas on the transmitter side and the receiver side, respectively. Looking at this in detail as shown in FIG. 2 illustrates an abstract model of a MIMO system with m (= n ) antennas.

The sender can receive multiple signals at the same time as s ₁ , s ₂ , ..., s _m (ignoring the time variable t in the figure). In addition, the receiver can receive and output multiple signals simultaneously indicated by r ₁ , r ₂ , ..., r _m (ignoring the time variable t in the figure). Each original signal s ₁ , s ₁ , ..., s _m , which can appear as a complex number, is transformed and mixed before being sent to the receiver, where w ₁ = defines how each signal is transformed. [w ₁₁ w ₁₂ ... w _1m ] ^T , w ₂ = [w ₂₁ w ₂₂ ... w _2m ] ^T is a weight vector and a combination of weight vectors W = [w ₁ w ₂ w ₃ ... w _m ] is called a steering matrix or a weight vector matrix. The signal transmitted from each antenna is the angle of W · s = u = [u ₁ u ₂ ... u _m ] ^{T which} is the product of the weight vector matrix and the original signal vector s = [s ₁ s ₂ ... s _m ] ^T Element. That is, u _k is transmitted in the k th antenna. The receiver also performs the necessary tasks using the weight vector. When formulating the model illustrated in FIG. 2, r (t) = VHW s (t).

Manipulation of the weight vector can produce the desired signal or waveform. Manipulation of the weight vector is called beamforming, and the result of the beamforming is essentially the product of the signal and the weight vector, or when processing multiple signals. It can be represented by the product of a vector matrix.

3 is a schematic configuration diagram of a data transmission apparatus in a multi-antenna-based multi-hop ad hoc network according to an embodiment of the present invention, FIG. 4 is a conceptual diagram illustrating a method of transmitting multiple signals in a transmission apparatus, and FIG. 5 is a reception diagram. A diagram illustrating a process of receiving multiple signals from a relay node in an apparatus.

Referring to FIG. 3, a data transmission apparatus in a multi-antenna based multihop ad hoc network includes a transmitting apparatus 100, a relay node 200, and a receiving apparatus 300. The transmitting device 100 includes at least two antennas. In the present embodiment, only one transmitting apparatus is shown, but the data transmitting apparatus according to the present invention may be configured with a plurality of transmitting apparatuses. In addition, in the case of the present embodiment, the transmitting apparatus is described as having two antennas, but the transmitting apparatus is equally applicable to the case of having N antennas.

The relay node 200 includes a plurality of relay nodes, the plurality of relay nodes constitute a plurality of data transmission paths, and each data transmission path includes at least one relay node. Each relay node 200 also includes at least two antennas, and includes the number of antennas corresponding to the number of antennas of the transmitting device. In the present embodiment, two data transmission paths are configured, and each data transmission path P _A and P _B includes three relay nodes. At this time, the data transmission path is set by a routing technique for setting an optimal path.

The receiving device 300 also includes at least two antennas, and includes an antenna corresponding to the number of antennas of the transmitting device 100. In the present embodiment, only one receiving apparatus is illustrated, but the data transmitting apparatus according to the present invention may be configured with a plurality of receiving apparatuses. In addition, in the case of the present embodiment, the receiving apparatus has been described as having two antennas, but the same applies to the case where the receiving apparatus has N antennas.

Two independent data transmission paths, that is, an A data transmission path P _A and a B data transmission path P _B , are formed between the transmitting device 100 and the receiving device 300. This data transmission path is set up a path that minimizes the collision between nodes using a routing technology to set up multiple paths. At this time, each data transmission path is composed of different relay nodes.

The transmitting device 100 transmits a signal obtained by performing dirty paper coating on different original signals to the relay node configuring each data transmission path. Each relay node receives a different signal transmitted from a transmitting device, and simultaneously transmits to the next relay node or receiving device. The receiving device 300 receives signals from the last relay node of each data transmission path, and decodes the received signal to detect the original signal.

Referring to FIGS. 4 and 5, the transmission device A simultaneously transmits two signals to two relay nodes B and C using the following dirty paper coding technique. When transmitting device A intends to transmit two signals s1 (t) and s2 (t) to relay node B and relay node C, signal r (t) = [r _B1 (t) r _C1 (t)] is determined as follows.

r _B1 (t) = s ₁ (t) R _1,1,

r _C1 (t) = s ₁ (t) R _1,2 + s ₂ (t) R _2,2

In Figure 4, H _AB is the channel between node A and node B, H _AC is the channel between node A and node C, w _B is the weight vector matrix of B, w _C is the weight vector matrix of C, and R is It is defined as the result of QR factorization. The transmission signal thus determined is transmitted to the relay nodes B and C without causing mutual interference.

The relay nodes B and C transmit each signal transmitted from the transmitting device A to the next relay node at the same time as the reception. This is possible through the adjustment of the respective weight vector matrices W _B and W _C. Assume that W _C is a combination of two weight vectors [w _C1 w _C2 ] and that channel between antennas i and j of C is h _ij , and N is the number of antennas of relay node C, as shown in FIG. 4. When w _C1 is used to receive a signal from the transmitting device A, w _C2 is used for signal transmission by setting the w _C2 and w _C1 relations to satisfy the following expression (3).

[Equation 3]

w _C2 ^H Hw _C1 = 0

Where _{H = [h ij], i} , j = 1, ..., N and for all k = 1 h _kk.

5, it receives the final destination R Knowing each channel H _CR between the channel H _BR, C, and R between the weight vector and the B and R used in the B and C the signals from each of the relay nodes at the same time, Decoded to detect the original signal s1 (t) and s2 (t) transmitted from the transmitting device.

FIG. 6 is a schematic configuration diagram of the transmission apparatus illustrated in FIG. 3, FIG. 7 is a schematic configuration diagram of the relay node illustrated in FIG. 3, and FIG. 8 is a schematic configuration diagram of the reception apparatus illustrated in FIG. 3. .

Referring to FIG. 6, a transmission apparatus 100 of a data transmission apparatus in a multi-antenna-based multihop ad hoc network includes a transmission weight vector adjusting unit 110, an encoding unit 120, a transmission unit 130, and a transmission control unit 140. And a transmit antenna 150.

The transmission waiter vector controller 110 performs a function of calculating a weight vector matrix, and when the signal is transmitted through a plurality of antennas, the weight vector matrix adds weights according to the state of the channel to provide a signal for the terminal. To receive it. This weight vector matrix removes the interference component between the antenna of the relay node or the antenna of the receiving device.

The encoder 120 performs dirty paper coding on the original signal under the control of the transmission weight vector adjusting unit 110 to remove interference between the relay nodes or the antennas of the receiving apparatus. That is, the encoder 120 aligns the signals using the weight vector matrix provided from the transmission weight vector controller 110 and performs dirty paper coding.

The transmitter 130 receives a signal output from the encoder 120, that is, a dirty paper coded signal, and transmits the signal to each relay node through the transmit antenna 150. The transmission control unit 140 controls operations of each component of the transmission apparatus, that is, the transmission weight vector adjusting unit 110, the encoding unit 120, and the transmission unit 130.

Referring to FIG. 7, each relay node includes a relay receiver 210, a relay weight vector controller 220, a relay transmitter 230, a relay controller 240, and a relay antenna 250.

The relay receiving unit 210 receives a signal transmitted from the transmitting device 100, and the relay weight vector adjusting unit 220 calculates and applies a weight vector to be used when transmitting to the next relay node based on the weight vector used when receiving the signal. It performs the function. In detail, a weight vector used when receiving a signal from a transmitting apparatus and a weight vector satisfying the above-described Equation 3 are set and used to transmit a signal to a next relay node.

The relay transmitter 230 beamforms the weight vector calculated by the relay weight vector controller 220 to the signal received by the relay receiver 210, and then transmits the weight vector to the next relay node or the receiver through the relay antenna 250. do.

Referring to FIG. 8, the receiver 300 includes a receiver 310, a decoder 320, a receiver controller 330, and a receiver antenna 340.

The receiving unit 310 receives a signal from each relay node through the receiving antenna 340 and transmits the signal to the decoding unit 320. The decoding unit 320 decodes the dirty paper coded signal performed by the transmitter to detect the original signal transmitted by the transmitter.

Referring to FIG. 9, first, a plurality of data transmission paths that are independent of each other in a multi-hop ad hoc network are set (S10).

When the data transmission path is established, the transmitting apparatus calculates a weight vector matrix for removing the interference component between the antenna of the relay node or the antennas of the receiving apparatus (S20).

Then, the dirty signal coding is applied to mutually different original signals to be transmitted through the plurality of data transmission paths to generate a transmission signal (S30). A process of transmitting the generated transmission signal to each relay node through a plurality of antennas is performed (S40).

Each relay node performs a process of receiving a transmission signal and calculating a weight vector to be used when transmitting the received transmission signal to a terminal (node) (S50). After beamforming is applied to the received transmission signal using the calculated weight vector, a process of transmitting to the next terminal is performed (S60).

After determining whether the terminal is a receiving device or a relay node (S70), if the terminal is a relay node, the process returns to step S50 and repeats the above process. On the other hand, when the terminal is a receiving device performs a process of decoding the received transmission signal to detect the original signal transmitted by the transmitting device.

What has been described above is merely an exemplary embodiment of a data transmission apparatus and method in a multi-antenna-based multi-hop ad hoc network according to the present invention, and the present invention is not limited to the above-described embodiment and is claimed in the following claims. As will be appreciated, those skilled in the art to which the present invention pertains will have the technical spirit of the present invention to the extent that various modifications can be made without departing from the gist of the present invention.

Claims

A data transmission apparatus in a multi-antenna based multihop ad hoc network,

A transmission device comprising two or more antennas;

A receiving device including two or more antennas; And

And a relay node forming a plurality of data transmission paths independent of the transmitting device and the receiving device, wherein each data transmission path includes a plurality of relay nodes, and each relay node includes two or more antennas. ,

The transmitting device transmits a signal obtained by performing dirty paper coating on different original signals to a relay node configuring each data transmission path,

Each of the relay nodes receives a signal transmitted from the transmitting device and simultaneously transmits the signal to the next relay node or the receiving device.

The receiving device receives a signal from each of the last relay nodes of each data transmission path, and decodes the received signal to detect the original signal, the data transmission device in a multi-antenna based multi-hop ad hoc network.
The method of claim 1,

The transmitting device,

A transmission waiter vector adjusting unit configured to calculate a weight vector matrix for allowing the relay node or the receiving device to receive a desired signal by applying weights according to channel states when transmitting signals through a plurality of antennas; And

In order to remove the interference between the antennas of the relay node or the receiving device, in the multi-antenna-based multi-hop ad hoc network, characterized in that it comprises an encoder for performing a dirty paper coding on the original signal using the weight vector matrix and outputs it. Data transmission device.
The method of claim 2,

The transmitting device,

A transmitter which receives the signal output from the encoder and transmits the signal to each relay node through a transmission antenna; And

And a transmission control unit for controlling operations of the transmission weight vector adjusting unit, the encoding unit, and the transmitting unit.
The method of claim 1,

Each relay node,

A relay receiver which receives a signal transmitted from the transmitter;

A relay weight vector adjusting unit configured to calculate and apply a weight vector to be used for transmission to the next relay node based on the weight vector used when the signal is received; And

And applying a beamforming to the signal received by the relay receiver, the weight vector calculated by the relay weight vector control unit, and then transmitting the signal to the next relay node or receiving device through a relay antenna. Data transmission device in a multi-hop ad hoc network.
The method of claim 4, wherein

The relay weight vector adjusting unit sets a weight vector used to receive a signal and a weight vector satisfying the following expression, and is used to transmit a signal to a next relay node or a receiving device.

[expression]

w C2 H Hw C1 = 0

Where H = [ h ij ], i, j = 1, ..., N, h kk = 1 for all k ,

Assume that the weight vector matrix of any relay node is W C , where W C is a combination of weight vectors [w C1 w C2 ], h ij is a channel between antennas i and j of the relay node, N Is an arbitrary number of relay node antennas, w C1 is a weight vector used when receiving the signal, and w C2 is a weight vector used when transmitting a signal to a next relay node or a receiving device. Data transmission device in hop ad hoc network.
The method of claim 1,

The receiving device,

Receiving unit for receiving a signal from each relay node through a receiving antenna; And

And a decoding unit to decode the received signal and detect an original signal transmitted from the transmitting apparatus.
The method of claim 1,

The data transmission path is a data transmission apparatus in a multi-antenna-based multi-hop ad hoc network, characterized in that the optimal path is set by a routing technique.
A data transmission method in a multi-antenna based multihop ad hoc network,

Establishing a plurality of mutually independent data transmission paths within a multi-hop ad hoc network;

The transmitting device calculates a weight vector matrix for removing interference components between the antenna of the relay node or the antennas of the receiving device;

Generating a transmission signal by applying dirty pattern coding to mutually different original signals to be transmitted through the plurality of data transmission paths;

Transmitting the generated transmission signal to each relay node through a plurality of antennas;

Each of the relay nodes receiving a transmission signal and calculating a weight vector for use in transmitting the received transmission signal to a subsequent terminal; And

And applying beamforming to the received transmission signal by using the calculated weight vector, and transmitting the beamforming to a next terminal.
The method of claim 8, wherein

Determining whether the terminal is a receiving device or a relay node; And

As a result of the determination, when the terminal is a relay node, the method returns to calculating a weight vector to be used when transmitting the received transmission signal to the terminal. When the terminal is a receiving device, decoding is performed on the received transmission signal. And detecting the original signal transmitted by the transmitting apparatus.
The method of claim 8,

The step of calculating the weight vector to be used when transmitting the received transmission signal to a subsequent terminal may be used when transmitting a signal to a next relay node or receiving apparatus by setting a weight vector used for receiving a signal and a weight vector satisfying the following expression. ,

[expression]

w C2 H Hw C1 = 0

Where H = [ h ij ], i, j = 1, ..., N, h kk = 1 for all k ,

Assume that the weight vector matrix of any relay node is W C , where W C is a combination of weight vectors [w C1 w C2 ], h ij is a channel between antennas i and j of the relay node, N Is an arbitrary number of relay node antennas, w C1 is a weight vector used when receiving the signal, and w C2 is a weight vector used when transmitting a signal to a next relay node or a receiving device. Method of data transmission in hop ad hoc network.