KR20080051999A - Method and system for repeating with spatial division multiplexing - Google Patents

Abstract

A relay method and system using spatial division multiplexing are provided to combine a BS including multi-antennas and repeaters efficiently, thereby improving sector throughput and performing data stream transceiving easily using SDMA(Space Division Multiple Access) regardless of a sub channel structure even in an OFDM(Orthogonal Frequency Division Multiplexing) system. A relay system performs wireless communication with a terminal positioned at a shadow zone or the outside of a cell. The relay system includes at least one repeater and a BS(Base Station). The at least one repeater performs wireless communication with a terminal positioned in a relay zone managed by a relay antenna. The BS includes BS antennas more than the number of repeaters. Each of the BS antennas corresponds to each of relay antennas one to one. The each BS antenna transceives signals for wireless communication in correspondence to each different relay antenna.

Description

Relay method and system using space division multiple access method {Method and System for Repeating with Spatial Division Multiplexing}

1 is a view briefly illustrating a connection method between a base station and an optical repeater using a single antenna;

2 is a diagram briefly illustrating a connection method between a base station and an optical repeater using multiple antennas;

3 is a view briefly illustrating a connection method between a base station and an RF repeater using multiple antennas;

4 is a diagram schematically illustrating a connection structure between a base station and a repeater using a space division multiple access scheme according to a first embodiment of the present invention;

5 is a diagram schematically illustrating a connection structure between a base station and a repeater using a space division multiple access scheme according to a second embodiment of the present invention;

6 is a signal flow diagram between a base station, a repeater, and a terminal for explaining a relay method using a space division multiple access scheme according to an embodiment of the present invention.

The present invention relates to a relay method and system using a space division multiple access scheme. More specifically, the present invention relates to a connection structure and a relay method between a base station and a repeater in a mobile communication system using a space division multiple access scheme.

Among wireless transmission technologies, many techniques for improving sector throughput using multiple antennas have been studied. Spatial Division Multiplexing (SDM) is a method of obtaining multiplexing gains by transmitting different signals to multiple antennas among various techniques for improving sector throughput. .

Recently, a precoding SDM technique for forming multiple beams orthogonal to each other or having low interference with each other and carrying each data stream is also widely used as a technique for increasing capacity. The SDM or precoding SDM scheme can transmit multiple streams to a single terminal or simultaneously transmit data streams to multiple terminals. Such a scheme is called a spatial division multiple access scheme (SDMA: SDMA) or precoding SDMA. The SDMA scheme or the precoding SDMA scheme may be applied when transmitting a data stream to the terminal through the downlink or receiving a data stream from the terminal through the uplink.

In order to obtain the maximum transmission gain through SDMA or precoding SDMA, as many data streams as possible must be transmitted at the same time, which is possible only when the signal-to-noise ratio (SNR) of the terminals participating in the multiple transmission is high. .

At this time, the terminal located near the base station has a high reception signal-to-noise ratio, so that it is easy to apply the SDMA method, but the reception signal-to-noise ratio of the terminal located far from the base station is lowered, so it is easy to apply the SDMA method. Not. Accordingly, the base station can use the SDMA method only in a part of the cell (area close to the base station), and thus does not meet the original purpose of increasing the sector capacity.

Meanwhile, in the mobile communication system, a repeater is used to solve the shadow area in the cell or to expand the coverage. Repeaters installed in the shadow area improve the received signal-to-noise ratio to eliminate the shadow area, and repeaters installed outside the cell radius of the base station extend the coverage of the base station.

As such a repeater, an optical repeater, an RF repeater, a microwave repeater, and the like are used. At this time, the connection between the repeater and the base station may be made in various ways.

1 is a diagram briefly illustrating a connection method between a base station and an optical repeater using a single antenna.

A base station using a single antenna and an optical repeater (first repeater and second repeater) located in a shadow area are connected by using an optical fiber. Here, the first repeater is an optical repeater installed in a shaded area in the base station, and the second repeater is an optical repeater installed in an area outside the cell radius of the base station to expand the coverage of the base station.

At this time, the demodulator of the base station converts the RF signal to be transmitted into a digital or analog signal, and then transmits it to the first repeater and the second repeater through an optical cable connected to a single antenna. The first repeater and the second repeater converts the received digital or analog signal back to an RF signal, amplifies it, and sends the same to the relay area in charge.

According to the connection method between the base station and the optical repeater using a single antenna conventionally used as shown in Figure 1, the connection between the base station and the optical repeater of the MIMO (Multi-Input Multi-Out) method for transmitting and receiving data using a plurality of antennas The method can be estimated.

2 is a diagram schematically illustrating a connection method between a base station and an optical repeater using multiple antennas.

A base station using multiple antennas and an optical repeater located in the shaded area are also connected using an optical cable. At this time, each optical repeater must include the same number of antennas as the base station, and the multiple antennas of the optical repeater and the multiple antennas of the base station must be matched one-to-one.

According to this connection, it is possible to transmit the data stream using the SDMA method to the terminal located in the relay area. However, as a plurality of antennas and a plurality of optical cables are used for such a connection, a problem arises in that a large installation cost is consumed.

3 is a diagram schematically illustrating a connection method between a base station and an RF repeater using multiple antennas.

In a relay system using an RF repeater, the RF signal transmission between the base station and the RF repeater is performed over the air. Accordingly, in the implementation of the relay system, the installation cost of the optical cable can be reduced, and the design of the relay system can be easily performed.

The base station using multiple antennas and the RF repeater located in the shadow area receive the RF signal from the base station using the same number of receive antennas as the multiple antennas of the base station. Then, each received signal is amplified and transmitted to the relay region through the same number of transmit antennas as the multiple antennas of the base station. That is, the RF repeater should include the same number of receive antennas and transmit antennas as the number of multiple antennas of the base station. Accordingly, the connection between the base station and the RF repeater can transmit the data stream using the SDMA method, and it has advantages such as the reduction of the installation cost of the optical cable and the ease of design of the relay system, but each repeater must have a plurality of antennas. There is a problem that occurs a lot of installation costs.

In order to solve this problem, the present invention has no economic burden compared to the implementation of the relay system in the base station using a single antenna when implementing the relay system of the multi-antenna base station for increasing the sector capacity, Provided is a connection structure between a base station and a repeater which can be efficiently used, and a relay method using the same.

In order to achieve the above technical problem, the relay system according to the first embodiment of the present invention is a relay system for performing wireless communication with a terminal located outside a shadowed area or a cell, and in a relay area controlled by one relay antenna. One or more repeaters for performing wireless communication with a located terminal; And a base station antenna having more than the number of repeaters, each base station antenna corresponding to the relay antenna one-to-one, each corresponding to a different relay antenna includes a base station for transmitting and receiving signals for wireless communication.

In addition, the relay system according to the second embodiment of the present invention is a relay system for performing wireless communication with a terminal located outside the shadowed area or cell, the terminal and wirelessly located within the relay area jurisdiction using two or more relay antennas One or more repeaters to perform communication; And a base station antenna more than the number of all the relay antennas of the one or more repeaters, each base station antenna corresponding to one relay antenna in one-to-one correspondence, each corresponding to a different relay antenna for transmitting and receiving signals for wireless communication It includes.

In addition, the relay method according to the present invention is a relay method in a repeater for transmitting a data stream received from a base station to a terminal located in a relay area that has jurisdiction. Receiving a pilot signal and transmitting the pilot signal to a jurisdiction relay area; (b) receiving relay region identification information including location information from a terminal and transmitting the relay area identification information to a base station antenna connected one-to-one; And (c) transmitting the data stream transmitted from the base station antenna using a spatial division multiple access scheme.

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.

In addition, when a part is said to "include" a certain component, this means that it may further include other components, except to exclude other components unless otherwise stated.

4 is a diagram schematically illustrating a connection structure between a base station and a repeater using a space division multiple access scheme according to a first embodiment of the present invention.

In the connection structure between the base station and the repeater according to the embodiment of the present invention, the base station includes N multiple antennas, and the repeater includes a single antenna. The single antenna of the repeater is connected one-to-one with each antenna of the base station. Accordingly, the base station can accommodate N repeaters.

In order to use the space division multiple access scheme, the antennas of the base station and the antennas of the repeater are independently connected one by one. As the antenna of the base station and the antenna of the repeater are independently connected, signals for each base station antenna are transmitted without interfering with each repeater.

As such, it is preferable to use an optical cable to independently connect the antenna of the base station and the antenna of the repeater, and the repeater uses an optical repeater. In this case, a microwave repeater using a different frequency for each antenna may be used since interference does not occur in signal transmission. However, in the RF repeater, since the RF signal of the first antenna of the base station can be received in the second repeater, the antenna of the base station and the antenna of the repeater are not independently connected. Accordingly, in the connection structure between the base station and the repeater according to the first embodiment of the present invention, it is not preferable to use an RF repeater.

In the connection structure between the base station and the repeater illustrated in FIG. 4, the terminal may identify the relay area currently located using the base station antenna identifier. For example, the terminal located in the first relay region receives a pilot signal transmitted from the first base station antenna through the first repeater. The terminal located in the second relay region receives the pilot signal transmitted from the second base station antenna through the second repeater.

In order to use a MIMO (Multi-Input Multi-Out) scheme in which a base station including a plurality of antennas transmits and receives different data using each antenna, each base station antenna transmits a unique pilot signal. Accordingly, the terminals located in each relay region compare the power of the received pilot signal to identify the base station antenna identifier of the pilot signal having the high power. Accordingly, the terminal can check whether it is located in the area of the repeater connected to the antenna of the base station.

In this case, since the pilot signal for each antenna is uniformly received, the terminal not belonging to the relay region may be located in the hydrometer region, that is, the base station region, to receive the data stream directly from the base station antenna.

At this time, in order to confirm the relay region, it is also possible to use a training signal for synchronizing with a terminal other than the pilot signal.

After confirming the relay area in which the terminal is located, the terminal generates the relay area confirmation information including information on the identified relay area and feeds it back to the base station, and the base station receiving the feedback information uses the received relay area confirmation information to generate a space. Performs data stream transmission through the division multiple access method. Here, the terminal located in the base station area also feeds back relay area confirmation information indicating that the terminal receives the data stream directly from the base station.

The base station selects terminals for each antenna that do not generate mutual interference during transmission and reception using the relay region identification information received from the plurality of terminals. Then, the data stream is simultaneously transmitted and received to the terminal selected for each antenna using the SDMA scheme.

SDM in Orthogonal Frequency Multiplexing Division Access (OFMDA) is mainly used in a subchannel structure in which subcarriers are adjacent to form a band. The band subchannel structure is applicable to a region in which the movement speed of the terminal is low. In a diversity subchannel structure in which subcarriers are separated from each other, it is difficult to use SDM because channel characteristics are different for each subcarrier. However, in the structure according to FIG. 4, terminals are already divided according to each relay area, and this is a classification irrespective of the subchannel structure, so that SDM can be efficiently applied. That is, SDM is applied irrespective of the subchannel structure, and since the diversity subchannel structure that is robust to the movement speed of the terminal can be used, the SDM is also robust to mobility.

The connection structure between the base station and the repeater according to FIG. 4 is the same as a conventional single antenna base station, and one optical cable is wired in connecting the base station and each repeater, and the repeater is also provided with one RF transceiver module. Accordingly, the repeater can be installed at the same cost as the repeater installation cost in the existing single antenna base station.

In the connection structure between the base station and the repeater according to FIG. 4, the repeater uses only one antenna. However, the repeater may include a plurality of antennas and transmit and receive data streams using the MIMO scheme.

5 is a diagram schematically illustrating a connection structure between a base station and a repeater using a space division multiple access scheme according to a second embodiment of the present invention.

5 shows a connection structure between a repeater using two relay antennas and a base station including four base station antennas. At this time, each relay antenna is connected to the base station antenna, respectively. That is, as shown in the example of FIG. 5, the first base station antenna and the second base station antenna are connected to the first repeater, and the third base station antenna and the fourth base station antenna are connected to the second repeater.

Through such a connection structure, the terminals located in each relay region check the base station antenna identifier through the pilot signal of the base station transmitted from the relay antenna, thereby determining whether they are located in the repeater's area connected to the antenna of which base station. It may be determined whether to receive a data stream transmitted from the base station through the antenna. As such, when the relay region check is completed in the terminal, the relay region check information including the identified relay region information is generated and transmitted to the base station.

The base station that receives the relay region identification information from the relay antenna connected through the optical cable classifies the terminal for each relay region or the base station antenna and performs scheduling so that the SDMA scheme can be performed without mutual interference.

At this time, in the connection structure between the base station and the repeater according to FIG. 4, only one antenna is installed in the relay area, whereas the structure according to FIG. 5 uses multiple antennas, so that the maximum data per terminal in the relay area is larger than that in FIG. 4. It is possible to increase the peak data rate.

Here, in the connection structure between the base station and the repeaters according to FIGS. 4 and 5, only some antenna signals of the base station antennas are transmitted to the relay region. At this time, if common control information that should be received by all terminals provided with the corresponding base station is transmitted only to the first antenna of the base station, a situation in which the terminal of some relay region may not receive the common control information may occur.

In order to prevent such a situation, the base station and repeater connection structure according to the present invention should use the antennas of all base stations in transmitting common control information. Accordingly, the common control information is cyclically delayed and transmitted through all base station antennas according to the cyclic delay diversity, so that all terminals located in the base station area and the relay area controlled by the repeater receive the common control information. Do it.

6 is a signal flow diagram between a base station, a repeater, and a terminal for explaining a relay method using a space division multiple access scheme according to an embodiment of the present invention.

As shown in FIG. 4 or FIG. 5, a base station connected by using a plurality of repeaters and an optical cable transmits pilot signals including respective base station antenna identifiers using a plurality of antennas included (S610).

The pilot signal is transmitted to the repeater that is one-to-one correspondence with each antenna through the optical cable. The repeater amplifies the transmitted pilot signal and transmits it to an unspecified terminal located in the relay region. At this time, when the repeater includes a plurality of antennas, the pilot signal is transmitted as many as the antenna number, and each pilot signal amplified through the repeater antenna connected one-to-one with the base station antenna is transmitted.

The terminal located in the relay region of the repeater that has transmitted the pilot signal receives the pilot signal transmitted from the relay antenna (S620).

Upon receiving the pilot signal, the terminal compares the power values of the pilot signals of the received antennas and checks information regarding the number of antennas of the base station in the area of the repeater (S630).

In addition, the terminal generates relay area confirmation information including information on the located relay area in order to notify the base station of the located relay area (S640) and transmits the information to the relay. The repeater transfers the received relay region confirmation information to the base station using the optical cable (S640).

The base station confirms the position information of the terminal, that is, the information of the repeater in charge of the terminal, through the relayed region confirmation information fed back (S650).

Then, the base station distinguishes terminals that do not generate mutual interference during transmission and reception using the relay region identification information (S660), and transmits a data stream to the terminal using SDMA (S670).

In this case, the terminal that does not belong to the relay area that the relay is in control, and receives the data stream directly from the base station antenna receives the pilot signal directly from the base station antenna in step S620, and transmits the relay area information directly to the base station in step S640, S670 In step the data stream is received directly from the base station antenna.

6, only the downlink transmission for transmitting the data stream from the base station to the terminal is described in FIG. 6, but the data stream may be transmitted from the terminal to the base station through uplink transmission.

6, in step S620 for transmitting a pilot signal, S640 for transmitting relay area information, and S670 for transmitting a data stream, a portion indicated by a solid line between the base station and the repeater is piloted through a wired network such as an optical cable. The signal, the relay region information and the data stream are transmitted. The dotted line between the repeater, the terminal, the base station and the terminal means that the pilot signal, the relay region information and the data stream are transmitted through the wireless network.

However, when using a microwave repeater, transmission and reception of pilot signals, relay region information, and data streams between the base station and the repeater indicated by solid lines are performed wirelessly.

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

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.

As described above, according to the present invention, the sector capacity can be increased by efficiently combining a base station and a repeater including multiple antennas, and even in a mobile communication system using OFDM transmission, regardless of the subchannel structure, the spatial division multiple access Data stream transmission and reception using the scheme can be easily implemented.

In addition, since the number of antennas is not increased in order to increase the capacity of the base station, an economic effect of implementing a relay system at a cost similar to that of installing a repeater in a base station including a single antenna can be expected.

Claims (12)

In a relay system for performing wireless communication with a terminal located outside the shadow area or cell, At least one repeater for performing wireless communication with a terminal located in a relay area under jurisdiction using one relay antenna; And A base station including more base station antennas than the number of repeaters, each base station antenna having a one-to-one correspondence with the relay antenna, and corresponding to a different relay antenna to transmit and receive signals for wireless communication Relay system comprising a. In a relay system for performing wireless communication with a terminal located outside the shadow area or cell, One or more repeaters for wirelessly communicating with a terminal located in a relay area under jurisdiction using two or more relay antennas; And A base station antenna having more than the number of all the relay antennas of the one or more repeaters, each base station antenna corresponding to one relay antenna one-to-one, each corresponding to a different relay antenna to transmit and receive signals for wireless communication Relay system comprising a. The method of claim 2, A first antenna of the repeater, wherein the first antenna is one antenna arbitrarily selected from the relay antennas; a first base station antenna, wherein the first base station antenna is a randomly selected base station antenna among a plurality of base station antennas; And a second antenna of the repeater, wherein the second antenna is an arbitrarily selected antenna among the relay antennas other than the first antenna in the relay antenna. Relay system, characterized in that connected to the base station antenna. The method according to claim 1 or 2, And a wireless communication with the terminal using a spatial division multiplexing access (SDAMA). The method of claim 4, wherein The repeater is an optical repeater, wherein the relay antenna and the base station antenna is a relay system, characterized in that connected using an optical cable. The method of claim 4, wherein The repeater is a microwave repeater, And the plurality of base station antennas transmit and receive signals for the wireless communication to the one-to-one corresponding relay antennas using different frequencies. The method of claim 4, wherein The base station, And transmitting common control information for transmission to all terminals in the relay system using all of the base station antennas according to cyclic delay diversity. In a relay method for a repeater for transmitting a data stream received from a base station to a terminal located in the relay area jurisdiction, (a) receiving a pilot signal from a base station antenna connected one-to-one among a plurality of antennas included in the base station, and transmitting the pilot signal to the jurisdiction relay area; (b) receiving relay region identification information including location information from the terminal and transmitting the relay area identification information to the base station antennas connected one-to-one; And (c) transmitting a data stream transmitted from the base station antenna using a space division multiple access scheme; Relay method comprising a. The method of claim 8, Step (a) is, As the repeater includes two or more relay antennas, when a pilot signal is transmitted from two or more base station antennas connected in a one-to-one manner, each of the relay signals transmits the pilot signals through the two or more relay antennas. . The method according to claim 8, wherein Receiving the pilot signal and the data stream from the base station antenna in steps (a) and (c), or transmitting the relay area identification information to the base station antenna in step (b), wherein the base station antenna And an optical cable connecting the relay antenna one to one. The method of claim 8, Step (b) is, And relay region identification information including position information of the terminal identified through a comparison of power included in a pilot signal received from the terminal. The method of claim 8, Between step (b) and step (c), Confirming location information of the terminal included in the relay area identification information through a base station; And Distinguishing terminals which do not generate interference when the data stream is transmitted and received according to the relay region where the terminals are located; Relay method, characterized in that it further comprises.

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