KR101096182B1 - Cooperative Communications Method for Vehicular Communications - Google Patents

Abstract

The present invention relates to a cooperative communication method in vehicle communication.

In the present invention, in transmitting a signal from one vehicle to another vehicle, the signal of the transmitting vehicle passes through a roadside device or several vehicles, and then the signals having a plurality of paths are transmitted to the receiving vehicle and entered through the various paths in the receiving vehicle. This method combines and demodulates a signal.

The present invention can be expected to improve the communication performance according to the spatial diversity gain by defining the signal transmission scheme of the transmitting vehicle according to the position of the repeater in the vehicle communication.

Vehicle communication, cooperative communication, repeater, mobile communication, repeater

Description

Cooperative Communications Method for Vehicular Communications

The present invention relates to a cooperative communication method used in vehicle communication, and more particularly, to a cooperative communication method using a plurality of vehicles or roadside devices in vehicle communication.

The present invention is derived from a study conducted as part of the IT growth engine technology development project of the Ministry of Knowledge Economy and the Ministry of Information and Communication Research and Development. [Task management number: 2007-F-039-02, Task name: VMC technology development].

In conventional mobile communication systems, signal transmission using a repeater has been widely considered.

In particular, the standard of the next generation wireless communication system adopts a communication using a repeater as a standard.

In the case of receiving the signals of the repeaters at the receiving end, a cooperative communication technique for combining and demodulating the signals has been proposed.

This cooperative communication technique can be expected to improve communication performance through diversity gain.

Unlike a conventional mobile communication system, a vehicle communication system forms a communication network by communication devices mounted in each vehicle without control of a base station.

Vehicle communication has been considered to use one vehicle as a repeater, but the cooperative communication method using several vehicles or a roadside device (relay) has not been discussed until now. In other words, the existing cooperative communication method has not been discussed in the vehicle communication system.

In order to solve such a problem, the present invention is to provide a cooperative communication method using a plurality of vehicles or roadside devices in vehicle communication.

According to an aspect of the present invention, there is provided a cooperative communication method comprising: (a) a transmitting vehicle initializes a parameter of a transmitting vehicle, the parameter including a threshold distance and a maximum number of repeaters; Scanning signals for located repeaters; (b) selecting repeater information whose number of repeaters is within the maximum number of repeaters and confirming distances to the repeaters when receiving signals from the repeaters; (c) broadcasting the signal to the repeaters by setting a post-decoding or post-amplification transmission scheme according to the positions of the repeaters; (d) transmitting the signal to a receiving vehicle in the relays by the post-decoding transmission method or the post-decoding transmission method; And (e) storing the received signal in a buffer and combining and demodulating the received signal when the signal is received from all the repeaters.

According to an aspect of the present invention, there is provided a cooperative communication method comprising: (a) a transmitting vehicle initializes a parameter of a transmitting vehicle, the parameter including a threshold distance and a maximum number of repeaters, and sends signals for repeaters located in the vicinity of the transmitting vehicle; Scanning; (b) when the transmitting vehicle receives signals from the repeaters, selects repeater information whose number of repeaters is within the maximum number of repeaters and checks distances to the repeaters; (c) The transmitting vehicle sets the post-decoding transmission method or the post-amplification transmission method according to the positions of the repeaters, generates a space-time code matrix having a size of a predefined space-time code matrix, and then transmits all the row signals to the repeater. Broadcasting to the network; (d) transmitting the row signals of the corresponding space-time code matrix to the receiving vehicle by the post-decoding transmission method or the post-decoding transmission method, respectively, in the repeaters; And (e) storing the signals received from the repeaters in a buffer and then combining and demodulating the received signals when the signals are received from all the repeaters.

According to an aspect of the present invention, there is provided a cooperative communication method comprising: (a) a transmitting vehicle initializes a parameter of a transmitting vehicle, the parameter including a threshold distance and a maximum number of repeaters, and sends signals for repeaters located in the vicinity of the transmitting vehicle; Scanning; (b) when the transmitting vehicle receives signals from the repeaters, selecting repeater information whose number of repeaters is within the maximum number of repeaters and confirming distances to the repeaters; (c) the transmitting vehicle grouping and separating signals of a transmission group after decoding when the distance to the repeaters is smaller than the threshold distance, and determining the size of a space-time code matrix and broadcasting the signals to the repeaters; (d) demodulating the signals received from the transmitting vehicle, and then generating the space-time code matrix having the size of the space-time code matrix and transmitting a row signal corresponding to each repeater to the receiving vehicle; And (e) storing the signals received from the repeaters in a buffer and then combining and demodulating the received signals when the signals are received from all the repeaters.

By the above-described configuration, the present invention can expect the effect of improving the communication performance of the inter-vehicle communication.

The present invention can be expected to provide an effect of providing a cooperative communication method using a plurality of vehicles or roadside devices in vehicle communication.

The present invention can be expected to improve the communication performance according to the spatial diversity gain by defining the signal transmission scheme of the transmitting vehicle according to the position of the repeater in the vehicle communication.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding other components unless specifically stated otherwise. In addition, the terms “… unit”, “… unit”, “module”, “block”, etc. described in the specification mean a unit that processes at least one function or operation, which is hardware or software or a combination of hardware and software. It can be implemented as.

An embodiment of the present invention proposes a method of improving performance by applying a cooperative communication technique to vehicle communication.

1 is a diagram illustrating a conceptual diagram of a cooperative communication method in a vehicle communication system according to an exemplary embodiment of the present invention.

In a vehicle communication system according to an exemplary embodiment of the present invention, two vehicles directly transmit signals when a vehicle-S (Source) 100 tries to transmit a signal to a vehicle-D (Destination) 300. The signal transmitted from the vehicle-S 100 is transmitted to the vehicle-D 300 via the roadside device R (Relay) 200 or several vehicles (vehicle-R1, vehicle-R2) 200, rather than the scheme. Delivered. Vehicle-D 300 then demodulates the signals by combining the signals received from the various paths.

Here, the roadside device-R (200), the vehicle-R1 (200), the vehicle-R2 (200) serves as a relay for transmitting a signal received from the transmitting vehicle (100).

The relay role may be composed of one vehicle 200, one roadside device 200, several vehicles 200, and a roadside device 200 and several vehicles 200.

2 is a view showing a case in which there is only one vehicle as a repeater in the vehicle communication system of the present invention, Figure 3 is a view showing a case in which there is only one roadside device as a repeater in the vehicle communication system of the present invention.

2 and 3 may transmit a signal avoiding a shaded area to a vehicle communication system implementing cooperative communication using one repeater 200.

Here, the relays 200 may operate in a decode-and-forward (DF) or amplify-and-forward (AF) mode.

The post-decoding transmission method is a method for demodulating and remodulating a signal transmitted from the transmitting vehicle 100 and then transmitting the signal. The post-decoding transmission method simply amplifies and transmits the received signal.

The transmitting vehicle 100 may determine which mode to transmit a signal in the relay vehicle.

When there are several or one repeater, the signal can be relayed by selecting one of the post-decode transmission and post-amplification transmission. The transmitting vehicle 100 may select the relay method according to the position of the repeater.

The signal transmission method can be divided into three types.

The first cooperative communication method (Cooperative Communication Method 1, hereinafter referred to as 'CCM1') is used for general signals (Phase Shift Keying (PSK), Quadrature Amplitude Modulation (QAM), and Differential PSK When the DPSK)) is transmitted to the repeater in a broadcasting format, the repeaters 200 repeatedly transmit the signals from the transmitting vehicle 100 to the post-decoded transmission or the post-amplification transmission.

The second cooperative communication method (hereinafter referred to as 'CCM2') generates a space-time code matrix by using a space-time coding (STC) when the transmitting vehicle 100 transmits a signal. All signals of the space-time code matrix are broadcasted to the relays 200, and each of the relays 200 transmits the row signals of the corresponding space-time matrix to the receiving vehicle 300 by transmission after decoding or transmission after amplification.

In the third cooperative communication method (cooperative communication method 3, hereinafter referred to as 'CCM3'), when the transmitting vehicle 100 broadcasts a general signal to the relays 200, each of the repeaters 200 demodulates the received signal. After generating the space-time code matrix by using the demodulated signal and transmits the matrix signal of the corresponding space-time code to the receiving vehicle 300.

The receiving vehicle 300 demodulates the signal by combining the received signals in the three methods described above.

4 is a diagram for describing a cooperative communication method in vehicle communication corresponding to CCM1 according to an embodiment of the present invention.

First, the transmitting vehicle 100 initializes the parameters of the transmitting vehicle 100 and scans signals for the surrounding vehicles of the transmitting vehicle 100 (S100 and S102). Here, the parameter of the transmitting vehicle 100 means a threshold distance (Dth) and the maximum number of repeaters (Nmax).

The threshold distance is determined by the signal strength received from the surrounding vehicles 200 when the location information is received from the surrounding vehicles 200 or when there is no location information. The number of repeaters is predefined in the system.

When the transmitting vehicle 100 receives a signal from the surrounding vehicle 200 or the roadside device 200, the repeater number N selects repeater information within the maximum repeater number Nmax, and then the surrounding vehicle 200 or the roadside devices. Check the distance of 200 (S104).

The transmitting vehicle 100 separates the calls into a transmission group Gdf after decoding if the distance D of the repeater 200 is smaller than the threshold distance Dth, and splits the calls into a transmission group Gaf after the amplification if the distance D of the repeater 200 is smaller than the threshold value (S106). ).

Subsequently, the transmitting vehicle 100 determines whether there are more signals in the transmission groups after decoding than in the transmission groups after the amplification (S106).

The transmitting vehicle 100 sets the signal as a decoded transmission method when there are a lot of signals of the transmission groups after decoding, and sets the signal as a post-amplification transmission method when there are many signals of the transmission groups after amplification, and then transmits the signal to the corresponding relays 200. Broadcast (S108, S110).

Each of the repeaters 200 transmits the received signals to the receiving vehicle 300 in a transmission after decoding or transmission after amplification (S112).

The receiving vehicle 300 stores the received signals in a buffer and then demodulates the received signals by combining the received signals when the signals are received from all the repeaters 200 (S114 and S116).

5 is a diagram illustrating a cooperative communication method in vehicle communication corresponding to CCM2 according to an embodiment of the present invention.

The transmitting vehicle 100 initializes the parameters of the transmitting vehicle 100 and scans signals for the surrounding vehicles of the transmitting vehicle 100 (S200 and S202).

When the transmitting vehicle 100 receives a signal from the surrounding vehicle 200 or the roadside device 200, the number of repeaters selects repeater information within the maximum number of repeaters and then determines the distance of the surrounding vehicle 200 or the roadside device 200. Check (S204).

The transmitting vehicle 100 separates the signals into the transmission group Gdf after decoding if the distance D of the repeater 200 is smaller than the threshold distance Dth, and separates the signals into the transmission group Gaf after amplification if the distance D of the repeater 200 is smaller than the threshold value S206. ).

Subsequently, the transmitting vehicle 100 determines whether there are more signals in the transmission groups after decoding than in the transmission groups after the amplification (S206).

Subsequently, when there are many signals of the transmission groups after decoding, the transmitting vehicle 100 sets the signal as a post-decoding transmission method.

The transmitting vehicle 100 determines the transmission scheme and determines the size Nstc of the space-time code matrix.

The transmitting vehicle 100 compares the post-decoding transmission group (Gdf) and the predetermined maximum matrix size (Nstc_max) of the predetermined time-space code when the post-decoding transmission scheme is set, and the size of the matrix of the post-decoding transmission group when it is smaller than the maximum matrix size ( Gdf) is set to the size of the space-time code matrix, and when the size is larger than the maximum matrix size, the maximum matrix size is set to the size of the space-time code matrix (S208, S210, and S212). Here, the space-time code matrix means a predefined matrix.

Before space-time coding, data has digital values of 0 and 1, and the data consisting of 0 and 1 correspond to the space-time code matrix according to the number of repeaters.

The transmitting vehicle 100 compares the post-amplification transmission group Gaf with the pre-amplification transmission group Gaf and the matrix size based on the post-amplification transmission group when the transmission matrix 100 is smaller than the maximum matrix size Nstc_max. If the size Gaf is set to the size of the space-time code matrix and is larger than the maximum matrix size, the maximum matrix size is set to the size of the space-time code matrix (S214, S216, and S218).

As described above, even when the number of signals of the selected group is large when determining the size of the actual space-time code matrix of Nstc, the size of the space-time code matrix is determined by the defined space-time code matrix.

The transmitting vehicle 100 determines a transmission method (transmission after decoding or transmission after amplification), generates a space-time code matrix having a size of the space-time code matrix (Nstc by M), and serially transmits all the row signals of the matrix to the relay 200. Broadcast (S220, S222). Here, Nstc by M is M is an arbitrary integer, and depends on the format of a predefined space-time code matrix.

At this time, the transmitting vehicle 100 also transmits information about which row signals each of the repeaters 200 should transmit. That is, the transmitting vehicle 100 should inform the repeater of the specific number of row signals in the space-time code matrix-type signal.

The relays 200 transmit the row signals of the corresponding space-time matrices to the receiving vehicle 300 in a post-decode transmission or post-amplification transmission manner (S224).

The receiving vehicle 300 stores the received signals in a buffer and then demodulates the received signals by combining the received signals when the signals are received from all the repeaters 200 (S226 and S228).

The difference between the CCM1 and the CCM2 described above is that a general communication signal is transmitted in the CCM1 and a space-time code matrix is transmitted in the CCM1.

6 is a view for explaining a cooperative communication method in vehicle communication corresponding to CCM3 according to an embodiment of the present invention.

The transmitting vehicle 100 initializes the parameters of the transmitting vehicle 100 and scans signals for the surrounding vehicles 200 of the transmitting vehicle 100 (S300 and S302).

When the transmitting vehicle 100 receives a signal from the surrounding vehicle 200 or the roadside device 200, the transmitter vehicle 100 selects repeater information within the maximum number of repeaters and checks the distance of the surrounding vehicle 200 or the roadside device 200 ( S304).

The transmitting vehicle 100 groups and separates signals of the transmission group Gdf after decoding, which is a case where the distance D of the repeater 200 is smaller than the threshold distance Dth (S306).

The CM3 determines the space-time code using the general communication signal in the transmitting vehicle (100) and the general communication signal in the repeater (200), so transmission after amplification is not possible. That is, the transmission after amplification is a method of amplifying the signal itself (general communication signal or space-time code) transmitted from the transmitting vehicle 100 by the repeater 200.

The transmitting vehicle 100 compares the size of the matrix of the transmission group after decoding to the maximum matrix size (Nstc_max) of the post-decoding transmission group (Gdf) and the predetermined space time code (Nstc_max). If the size is set to be larger than the maximum matrix size, the maximum matrix size is set to the size of the space-time code matrix (S308, S310, and S312).

The transmitting vehicle 100 broadcasts a signal to the relays 200, and at this time, the relay 200 also transmits information on which row of signals the relays 200 should transmit (S314).

The repeaters demodulate the signals received by the transmitting vehicle 100, generate a space-time code matrix of size Nstc by M, and transmit a row signal corresponding to each repeater 200 to the receiving vehicle 300 (S316).

The difference between CCM3 and CCM2 described above is that a space-time code matrix is generated in the repeater 200.

The receiving vehicle 300 stores the received signal in a buffer and then demodulates the received signals by combining the received signals when the signals are received from all the repeaters 200 (S318 and S320).

The present invention contemplates defining a signal transmission scheme of the transmitting vehicle 100 according to the position of the repeater (vehicle or roadside device) 200.

Three transmission schemes have been considered: communication using a general modulation scheme, communication using a space-time code, and a hybrid scheme.

Through the cooperative communication method according to the embodiment of the present invention, it is possible to expect an improvement in communication performance according to the spatial diversity gain.

The embodiments of the present invention described above are not implemented only by the apparatus and / or method, but may be implemented through a program for realizing functions corresponding to the configuration of the embodiment of the present invention, a recording medium on which the program is recorded And such an embodiment can be easily implemented by those skilled in the art from the description of the embodiments described above.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

1 is a diagram illustrating a conceptual diagram of a cooperative communication method in a vehicle communication system according to an exemplary embodiment of the present invention.

2 is a view showing a case in which there is only one vehicle as a repeater in the vehicle communication system of the present invention.

3 is a diagram illustrating a case where only one roadside device is a repeater in the vehicle communication system of the present invention.

4 is a diagram for describing a cooperative communication method in vehicle communication corresponding to CCM1 according to an embodiment of the present invention.

5 is a diagram illustrating a cooperative communication method in vehicle communication corresponding to CCM2 according to an embodiment of the present invention.

6 is a view for explaining a cooperative communication method in vehicle communication corresponding to CCM3 according to an embodiment of the present invention.

Claims (10)

In the cooperative communication method in a vehicle communication system, (a) the transmitting vehicle initializing a parameter of the transmitting vehicle, the parameter comprising a threshold distance and a maximum number of repeaters, and scanning signals for repeaters located in the periphery of the transmitting vehicle; (b) selecting repeater information whose number of repeaters is within the maximum number of repeaters and confirming distances to the repeaters when receiving signals from the repeaters; (c) broadcasting the signal to the repeaters by setting a post-decoding or post-amplification transmission scheme according to the positions of the repeaters; (d) transmitting the signal to a receiving vehicle in the relays by the post-decoding transmission method or the post-decoding transmission method; And (e) storing the received signal in a buffer and combining and demodulating the received signal when the signal is received from all the repeaters. Cooperative communication method comprising a. The method according to claim 1, In the step (c), If the distance to the repeaters is smaller than the threshold distance, the signal is divided into a post-decoding transmission group if the distance is greater than the threshold distance, and the signal is divided into a post-decoding transmission group. If the signal of the transmission group after the amplification is a lot, setting the signal to amplification and transmission method and broadcasting to the repeaters Cooperative communication method comprising a. In the cooperative communication method in a vehicle communication system, (a) the transmitting vehicle initializing a parameter of the transmitting vehicle, the parameter comprising a threshold distance and a maximum number of repeaters, and scanning signals for repeaters located in the periphery of the transmitting vehicle; (b) when the transmitting vehicle receives signals from the repeaters, selects repeater information whose number of repeaters is within the maximum number of repeaters and checks distances to the repeaters; (c) The transmitting vehicle sets the post-decoding transmission method or the post-amplification transmission method according to the positions of the repeaters, generates a space-time code matrix having a size of a predefined space-time code matrix, and then transmits all the row signals to the repeater. Broadcasting to the network; (d) transmitting the row signals of the corresponding space-time code matrix to the receiving vehicle by the post-decoding transmission method or the post-decoding transmission method, respectively, in the repeaters; And (e) storing the signals received from the repeaters in a buffer and combining and demodulating the received signals when the signals are received from all the repeaters. Cooperative communication method comprising a. The method of claim 3, In the step (c), If the distance to the repeaters is smaller than the threshold distance, the signal is divided into a post-decoding transmission group if the distance is greater than the threshold distance, and the signal is divided into a post-decoding transmission group. And setting the signal after the amplification to a transmission method if there are many signals in the transmission group after the amplification. Cooperative communication method comprising a. The method of claim 3, In the step (c), When the post-decoding transmission scheme is set, the transmitting vehicle compares a maximum matrix size of the post-decoding transmission group with a predetermined space-time code and, when smaller than the maximum matrix size, sets the size of the matrix of the post-decoding transmission group in the space-time code matrix. And setting the maximum matrix size to the size of the space-time code matrix when the size is larger than the maximum matrix size. The method of claim 3, In the step (c), When the transmission amplification transmission scheme is set, the transmitting vehicle compares the maximum amplification matrix size of the post-amplification transmission group with a predetermined space-time code and is smaller than the maximum matrix size. And setting the maximum matrix size to the size of the space-time code matrix when the size is larger than the maximum matrix size. The method of claim 3, In the step (c), The transmitting vehicle determines the size of the space-time code matrix and broadcasts all the row signals to the repeaters together with information on which row signals each relay should transmit in the form of the space-time code matrix. Cooperative communication method comprising a. In the cooperative communication method in a vehicle communication system, (a) the transmitting vehicle initializing a parameter of the transmitting vehicle, the parameter comprising a threshold distance and a maximum number of repeaters, and scanning signals for repeaters located in the periphery of the transmitting vehicle; (b) when the transmitting vehicle receives signals from the repeaters, selects repeater information whose number of repeaters is within the maximum number of repeaters and checks distances to the repeaters; (c) the transmitting vehicle grouping and separating signals of a transmission group after decoding when the distance to the repeaters is smaller than the threshold distance, and determining the size of a space-time code matrix and broadcasting the signals to the repeaters; (d) demodulating the signals received from the transmitting vehicle, and then generating the space-time code matrix having the size of the space-time code matrix and transmitting a row signal corresponding to each repeater to the receiving vehicle; And (e) storing the signals received from the repeaters in a buffer and combining and demodulating the received signals when the signals are received from all the repeaters. Cooperative communication method comprising a. The method of claim 8, In the step (c), The transmitting vehicle sets the size of the matrix of the decoded transmission group to the size of the space-time code matrix when it is smaller than the maximum matrix size compared with the maximum matrix size of the post-decoding transmission group and a predetermined space-time code. If the size is larger than the maximum matrix size, sets the size of the space-time code matrix. The method of claim 8, In the step (c), The transmitting vehicle determines the size of the space-time code matrix and broadcasts all the row signals to the repeaters together with information on which row signals each relay should transmit in the form of the space-time code matrix. Cooperative communication method comprising a.

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