KR20130101935A - System and method for joint transmission - Google Patents

Abstract

In order to provide a cooperative communication service to a terminal in an environment in which a cooperative communication providing system includes a cooperative communication area in which a first cell area by a first base station and a second cell area by a second base station overlap, a first base station and a first base station are provided. 2 When the first signal information and the second signal information transmitted from the base station is received, the terminal transmits and checks the first reception strength and the second reception strength of the signal received by the first base station and the second base station, respectively. If a request is made for a pause by an active timer, and the location of the terminal is changed after checking whether the location of the terminal is changed based on the first reception strength and the second reception strength, the threshold is set in advance by receiving time information from the paused timer. Check if the time is exceeded. If the threshold time is exceeded, the first base station and the second base station indicates whether the signal is transmitted to the terminal.

Description

System and method for joint transmission

The present invention relates to a cooperative communication providing system and method.

In general, joint transmission (JT) refers to a communication method in which a plurality of transmitters forming each cell cooperate with each other to achieve diversity gain to support a receiver by solving cell interference and multipath fading problems. Means. That is, when the terminal is located at a plurality of cell boundaries, it refers to a method in which cells simultaneously transmit signals to the terminal to obtain a transmission diversity gain and a multi input multi output (MIMO) effect.

Such cooperative communication facilitates information exchange between a plurality of transmitters, thereby reducing inter-cell interference and increasing frequency spectrum efficiency. However, since the cooperative communication has a sudden change in the wireless environment, the value for determining the entry / exit into the cooperative communication area is continuously changed even when the terminal is stopped, so the system must continuously look at the state of the terminal to reflect this. Accordingly, in order to reflect the state of the terminal in the system, it is necessary to provide a fast adaptation function, and in this case, there is a problem that it may cause an overload of the system.

Accordingly, the present invention provides a cooperative communication providing system and method for determining entry / exit of frequent cooperative communication areas of a terminal and processing the same according to suppression / exit.

A system for providing cooperative communication, which is a feature of the present invention, includes a cooperative communication region in which a first cell region by a first base station and a second cell region by a second base station overlap. Method for providing a cooperative communication service to the terminal in the environment,

Receiving first signal information and second signal information transmitted from the first base station and the second base station; Confirming a first reception strength and a second reception strength of a signal transmitted by the terminal from the first signal information and the second signal information respectively received by the first base station and the second base station; Requesting a pause with an active timer, and checking whether the position of the terminal has been changed based on the first reception strength and the second reception strength; If the location of the terminal is changed, receiving time information from the paused timer and checking whether a preset threshold time is exceeded; And if the threshold time has been exceeded, indicating whether the first base station and the second base station transmit a signal to the terminal.

The first signal information includes the first base station identification information, terminal identification information of the terminal, and a first reception strength received by the first base station with respect to a signal transmitted by the terminal to the first base station. The second signal information may include the second base station identification information, the terminal identification information of the terminal, and the second reception strength received by the second base station with respect to the signal transmitted by the terminal to the second base station.

Receiving the first signal information and the second signal information, confirming the terminal identification information from the first signal information and the second signal information, respectively, and the previous position of the terminal stored corresponding to the terminal identification information It may include the step of identifying.

The determining whether the location of the terminal is changed may include: determining whether a difference between the first reception strength and the second reception strength is greater than a preset entry threshold value if the previous location of the terminal is outside the cooperative communication area; If the difference between the first reception strength and the second reception strength is greater than the entry threshold, the terminal entering the cooperative communication area from the outside of the cooperative communication area and confirming that the location of the terminal has been changed; And if the difference between the first reception strength and the second reception strength is smaller than the entry threshold, the terminal may be located outside the cooperative communication area to confirm that the location of the terminal has not been changed. .

The determining whether the location of the terminal is changed may include determining whether a difference between the first reception strength and the second reception strength is smaller than a preset advance threshold if the previous location of the terminal is inside the cooperative communication area. ; If the difference between the first reception intensity and the second reception intensity is less than the advance threshold, the terminal advancing from the inside of the cooperative communication area to the outside of the cooperative communication area to confirm that the location of the terminal has been changed; And when the difference between the first reception intensity and the second reception intensity is greater than the advance threshold, confirming that the terminal is located inside the cooperative communication area and the location of the terminal has not been changed.

The step of indicating whether the signal is transmitted to the terminal may include updating and storing identification information of the terminal whose location is changed and current location information of the terminal.

In an environment including a cooperative communication region in which a first cell region by a first base station and a second cell region by a second base station overlap each other, which is another feature of the present invention for achieving the technical problem of the present invention, The system providing the cooperative communication service,

A signal information receiver configured to receive, from the first base station or the second base station, first signal information of a signal transmitted from the terminal to the first base station and second signal information of a signal transmitted to the second base station; A terminal location storage unit for storing information on a previous location of the terminal together with terminal identification information about the terminal; A timer for temporarily stopping the operating state by the control, resetting from the pause state to newly operate, changing the pause state to the operating state, and providing time information; And confirming terminal identification information from the first signal information and the second signal information to confirm previous position information of the terminal stored in the terminal location storage unit, and a signal included in the first signal information or the second signal information. And a terminal entry / exit determination unit configured to determine entry / exit of the terminal into the cooperative communication area based on reception strength information and time information received from the timer.

The cooperative communication providing system may include a transmission state change indicating unit requesting signal transmission to the first base station or the second base station in order to change the signal transmission from the terminal entry / exit determination unit to the terminal whose location information is changed. .

According to the present invention, it is possible to prevent a system overload for providing a cooperative communication service due to frequent entry / exit of a cooperative communication area of a terminal.

1 is an exemplary diagram illustrating a general cooperative communication method.
2 is a structural diagram of a cooperative communication providing system according to an embodiment of the present invention.
3 is a flowchart illustrating a cooperative communication providing method according to an embodiment of the present invention.

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. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. 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 this specification, a terminal includes a mobile station (MS), a mobile terminal (MT), a subscriber station (SS), a portable subscriber station (PSS) An access terminal (AT), and the like, and may include all or some of functions of a mobile terminal, a subscriber station, a mobile subscriber station, a user equipment, and the like.

In the present specification, a base station (BS) is an access point (AP), a wireless access station (Radio Access Station, RAS), a Node B (Node B), a transceiver station (Base Transceiver Station, BTS), MMR (Mobile Multihop Relay) -BS and the like, and may include all or part of functions such as an access point, a radio access station, a Node B, a base transceiver station, and an MMR-BS.

Hereinafter, a system and method for providing cooperative communication according to an embodiment of the present invention will be described with reference to the accompanying drawings. Before explaining the embodiment of the present invention, a general cooperation communication method will be described first.

1 is an exemplary diagram illustrating a general cooperative communication method.

As shown in FIG. 1, when the terminal 30 is located at the boundary of two sub-cells, that is, a cooperative communication area, the base stations 20 and 20 'located at different sub-cells with different identification information may simultaneously signal to the terminal. Send it. At this time, when it is determined whether the terminal 30 enters the cooperative communication area or the cooperative communication area, the terminal 30 receives a Sounding Reference Signal (SRS) transmitted to the base stations 20 and 20 'of the lower cells. Judging by the intensity.

That is, the base stations 20 and 20 'of the two lower cells check the reception strength of the SRS transmitted from the terminal 30, and the virtualization server 10 checks the magnitude of the reception strength of the two SRSs. It is judged whether the difference is larger than the preset value or smaller than the preset value to distinguish the entry or exit into the cooperative communication area. In this case, since the wireless environment such as transmitting the SRS is constantly changing, the reception strength value of the SRS is continuously changed even when the terminal 30 is not moving.

Therefore, an embodiment of the present invention describes a system and method that can provide cooperative communication by handling a change in the reception strength of a frequent SRS for a terminal. The cooperative communication providing system 100 determines whether to provide cooperative communication through information on the reception strength of the SRS transmitted from the base stations in cooperation with one or more base stations.

In the embodiment of the present invention will be described with an example that the cooperative communication providing system 100 performs the role of a virtualization server. In addition, a plurality of base stations linked to the cooperative communication providing system 100 will be described as an example of a first base station and a second base station. Assuming that an identifier of a first cell for an area of the first base station is "1", the second base station The identifier of the second cell for the region of is assumed to be "2".

2 is a structural diagram of a cooperative communication providing system according to an embodiment of the present invention.

As shown in FIG. 2, the cooperative communication providing system 100 includes a signal information receiving unit 110, a terminal entry / exit determination unit 120, a timer 130, a transmission state change indicating unit 140, and a terminal location storage unit. And 150.

The signal information receiver 110 receives signal information from the first base station and the second base station, respectively. Here, the signal information includes SRS reception strength information for receiving SRS from a terminal located at a cell area of the first base station and a second base station, cell identification information of a cell managed by each base station, and terminal identification information of a terminal transmitting the SRS. do.

That is, the terminal may be located in a place where the first cell of the first base station and the second cell of the second base station overlap (hereinafter, referred to as a `` cooperative communication area '' for convenience of description) or the area of the first cell or It may be located anywhere in the region of the second cell. In this case, when the terminal is located in the cooperative communication area, the first base station and the second base station simultaneously receive the SRS transmitted from the terminal.

If the terminal is located in any one of the region of the first cell or the region of the second cell, only the base station of the cell in which the terminal is located or the two base stations receive the SRS with different strengths. Accordingly, the signal information receiver 110 may receive SRS reception strength information for the same terminal from the first base station and the second base station at the same time, and receive the SRS reception strength information from any one of the first base station and the second base station. May be received.

The terminal entry / exit determining unit 120 checks the identification information of the terminal among the signal information received by the signal information receiving unit 110 and cooperates with a previous position of the terminal stored in the terminal position storage unit 150 to be described later. Check whether it is in the communication area or outside the cooperative communication area. First, after confirming the previous location information of the terminal, the at least one SRS reception strength information from the signal information.

When there is a plurality of SRS reception strength information, the difference between the plurality of SRS reception strengths is checked, and then it is determined whether the preset threshold is exceeded according to the position of the previous terminal. Since an embodiment of the present invention describes two base stations as an example, a difference between a first SRS reception strength value received from a first base station and a second SRS reception strength value received from a second base station is calculated.

If the previous location of the terminal is outside the cooperative communication area, the calculated difference value is determined to be larger than a threshold indicating the entry into the cooperative communication area. Check if it is smaller than the threshold indicating departure from the cooperative communication area. Here, it is known that the terminal advances from the cooperative communication area but to which area of the first base station or the second base station, and the detailed description is omitted in the embodiment of the present invention.

When the terminal entry / exit determination unit 120 confirms that the position of the terminal is changed, the terminal 130 controls the timer 130 that has been operating previously. In addition, time information is received from a timer 130 that has been previously operated and paused, and checks whether a predetermined threshold time has been exceeded.

If the threshold time is exceeded, the terminal enters the cooperative communication area or enters the cooperative communication area. Therefore, the terminal confirms that the location has changed according to the entry / exit of the terminal, and controls the timer 130 to pause. In addition, the location information of the terminal and the identification information of the terminal are transmitted to the terminal location storage unit 150 so that the previous location information is updated.

However, if the threshold time is not exceeded, it is determined that the SRS reception strength is changed according to the wireless environment. Accordingly, the terminal entry / exit determination unit 120 controls the timer 130 to pause until the separate signal information is input.

The timer 130 operates under the control of the terminal entry / exit determination unit 120. That is, the timer 130 requests that the terminal entry / exit determination unit 120 pause for the timer 130 that is already operating, or requests that the paused timer 130 continues to operate or pauses. When requesting the operation 130 newly, the operation of the timer 130 is controlled according to a request of the terminal entry / exit determination unit 120. In other words, when the location of the terminal is changed, for example, when the terminal enters or exits the cooperative communication area, the timer 130 newly resets the suspended state but does not change the location of the terminal. If not, it is operated in the paused state.

The timer 130 may be used to determine whether the terminal has entered the cooperative communication area or the time information in the paused state. In the embodiment of the present invention, a separate configuration of the timer 130 is described as an example, but the terminal entry / exit determination unit 120 may perform the function of the timer 130. In addition, the timer 130 will be described as an example of operating differently according to the identification information of the terminal.

The transmission state change indicating unit 140 transmits a signal to each base station that can communicate with the terminal according to a result of the terminal entry / exit determination unit 120 determining whether the terminal has entered the cooperative communication area or the cooperative communication area. Instructs the state change to.

That is, when the terminal entry / exit determination unit 120 determines that the terminal enters the cooperative communication area from the area of the first base station or the area of the second base station, the transmission state change indicating unit 140 determines the first base station and the second base station. Instructs to simultaneously transmit a signal to the terminal. However, if it is determined that the terminal has advanced into the area of the first base station or the area of the second base station from the cooperative communication area, the transmission state change indicating unit 140 transmits a signal to the terminal of either the first base station or the second base station. Instruct.

The terminal location storage unit 150 stores identification information of the terminal and previous state information of the terminal. The previous state information is information indicating whether the terminal is located in the cooperative communication area or in only one of the first base station area and the second base station area.

A method of providing cooperative communication through the system 100 described above will be described with reference to FIG. 3. For convenience of description, in the embodiment of the present invention, it is assumed that the terminal previously transmitted the SRS after entering the cooperative communication area from the first cell area of the first base station.

3 is a flowchart illustrating a cooperative communication providing method according to an embodiment of the present invention.

As shown in FIG. 3, when the signal information receiver 110 receives the first signal information from the first base station and receives the second signal information from the second base station (S100), the terminal entry / exit determination unit 120 is performed. The terminal confirms terminal identification information from the first signal information and the second signal information, respectively (S110). Here, the first signal information and the second signal information includes SRS reception strength information received from the terminal, identification information of each base station, and terminal identification information, respectively.

The terminal entry / exit determination unit 120 is a previous position of the terminal corresponding to the terminal identification information among the position information of the plurality of terminals already stored in the terminal location storage unit 150 based on the terminal identification information checked in step S110. Check the information (S120). In the embodiment of the present invention, since the terminal was previously assumed to be located in the first cell area of the first base station, the terminal entry / exit determination unit 120 confirms that the terminal was in the first base station area in step S120.

After confirming the previous position of the terminal, the terminal entry / exit determination unit 120 checks the SRS reception strength from the first SRS signal information and the second SRS signal information received in step S100 (S130). The SRS reception strength includes a reception strength at which the first base station receives the SRS (hereinafter referred to as P1) and a reception strength at which the second base station receives the SRS (hereinafter referred to as P2).

After checking the reception strength through step S130, the terminal entry / exit determination unit 120 requests to temporarily stop the timer operating as the timer 130 (S140). In this case, the timer 130 starts operation when the terminal is in the region of the first base station.

When the timer 130 is in the paused state, the terminal entry / exit determination unit 120 determines the position of the terminal based on the SRS reception strength P1 for the first base station and the SRS reception strength P2 for the second base station. Check whether the change (S150). That is, after calculating the difference between P1 and P2, it is determined whether the terminal enters the cooperative communication region or the cooperative communication region according to the previous position of the terminal.

To this end, the cooperative communication providing system 100 includes a threshold for identifying entry into the cooperative communication area (hereinafter referred to as an entry threshold) and a threshold for identifying entry from the cooperative communication area (hereinafter, The management system is set in advance. In step S150, the position change of the terminal may be determined using the entry threshold or the exit threshold based on the difference between P1 and P2 and the previous position information of the terminal checked in step S120.

In the embodiment of the present invention, the case of entering the cooperative communication area will be described as an example. In step S150, it is determined whether the difference between P1 and P2 is greater than the entry threshold. This may be expressed as Equation 1 below.

[Equation 1]

| Entry threshold | > | P1-P2 |

On the contrary, when determining whether or not to advance, check using the following equation (2).

&Quot; (2) "

| Entry threshold | <| P1-P2 |

If it is determined in step S150 that the difference between P1 and P2 is greater than the entry threshold, the position of the terminal is changed, so the terminal entry / exit determination unit 120 obtains and confirms time information from the paused timer 130. Then, it is checked whether the value for the obtained time information is larger than the value for the preset threshold time (S160). This is because the wireless environment in which the terminal transmits the SRS to the base station changes for various reasons, and thus it can be understood that the entry / exit of the cooperative communication area occurs frequently even when the terminal is stopped without changing its position.

Accordingly, the terminal entry / exit determination unit 120 processes the change in the SRS reception strength using not only the SRS reception strength of the base station but also the time information of the newly operated timer when the terminal changes its location, thereby providing cooperative communication. To reduce the load on the system 100. Therefore, in step S160, the terminal entry / exit determination unit 120 compares the previous time information according to the previous terminal position received from the timer 130 with a preset threshold time. The threshold time is compared as shown in Equation 3 below.

&Quot; (3) &quot;

"Previous time <entry event retention threshold time" or

"Previous time <exit event retention threshold time"

If the time length according to the previous time information is longer than the preset threshold time length, it is confirmed that the position of the terminal is changed from the first base station area to the cooperative communication area or vice versa, the terminal entry / exit determination unit 120 ) Resets the time at which transmission is stopped to the timer 130 and instructs a new timer to operate (S170). In addition, the terminal entry / exit determination unit 120 instructs to transmit a signal from both the first base station and the second base station to the corresponding terminal through the transmission state change indicating unit 140 (S180). In addition, the terminal transmits the terminal location information together with the terminal identification information to the terminal location storage unit 150 along with the signal transmission instruction to be updated.

However, when the difference between P1 and P2 calculated in step S150 is smaller than the threshold value, or when the previous time length is shorter than the threshold time length in step S160, it is confirmed that the position of the terminal has not been changed. Accordingly, the terminal entry / exit determination unit 120 maintains the state of transmitting a signal from the first base station to the terminal without any further instruction to the transmission state change indicating unit 140 (S190).

Using the timer as well as the SRS reception strength in this way, it is possible to reduce the load of the cooperative communication providing system 100 for the processing of fluctuations in the SRS reception value that changes from time to time, and enter the frequent cooperative communication area due to the actual measurement error It can reduce the processing load by entering.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

Claims (13)

A method for providing a cooperative communication service to a terminal in an environment in which a cooperative communication providing system includes a cooperative communication area in which a first cell area by a first base station and a second cell area by a second base station overlap.
Receiving first signal information and second signal information transmitted from the first base station and the second base station;
Confirming a first reception strength and a second reception strength of a signal transmitted by the terminal from the first signal information and the second signal information respectively received by the first base station and the second base station;
Requesting a pause with an active timer, and checking whether the position of the terminal has been changed based on the first reception strength and the second reception strength;
If the location of the terminal is changed, receiving time information from the paused timer and checking whether a preset threshold time is exceeded; And
If the threshold time is exceeded, indicating whether the first base station and the second base station transmit a signal to the terminal;
Cooperative communication providing method comprising a. The method of claim 1,
The first signal information includes the first base station identification information, the terminal identification information of the terminal and the first reception strength received by the first base station with respect to the signal transmitted by the terminal to the first base station,
The second signal information includes the second base station identification information, the terminal identification information of the terminal, and the cooperative communication including the second reception strength received by the second base station with respect to the signal transmitted by the terminal to the second base station. Way. The method of claim 2,
Receiving the first signal information and the second signal information,
Confirming terminal identification information from the first signal information and the second signal information, and confirming a previous position of the terminal stored corresponding to the terminal identification information;
Cooperative communication providing method comprising a. The method of claim 2,
Checking whether the location of the terminal has changed,
If the previous location of the terminal is outside the cooperative communication area,
Determining whether a difference between the first reception intensity and the second reception intensity is greater than a preset entry threshold value;
If the difference between the first reception strength and the second reception strength is greater than the entry threshold, the terminal entering the cooperative communication area from the outside of the cooperative communication area and confirming that the location of the terminal has been changed; And
If the difference between the first reception strength and the second reception strength is less than the entry threshold, confirming that the terminal is located outside the cooperative communication area and the location of the terminal has not been changed.
Cooperative communication providing method comprising a. The method of claim 2,
Checking whether the location of the terminal has changed,
If the previous location of the terminal is inside the cooperative communication area,
Determining whether a difference between the first reception intensity and the second reception intensity is smaller than a preset advance threshold;
If the difference between the first reception intensity and the second reception intensity is less than the advance threshold, the terminal advancing from the inside of the cooperative communication area to the outside of the cooperative communication area to confirm that the location of the terminal has been changed; And
If the difference between the first reception intensity and the second reception intensity is greater than the advance threshold, confirming that the terminal is located inside the cooperative communication area and the location of the terminal has not been changed.
Cooperative communication providing method comprising a. The method according to claim 4 or 5,
After confirming that the location of the terminal has been changed,
Controlling the paused timer to reset and operate
Cooperative communication providing method comprising a. The method according to claim 6,
After confirming that the location of the terminal has not changed,
Controlling the paused timer to continue running
Cooperative communication providing method comprising a. The method of claim 1,
Indicating whether to transmit a signal to the terminal,
Updating and storing identification information of the terminal whose location has been changed and current location information of the terminal;
Cooperative communication providing method comprising a. 9. The method of claim 8,
If the location of the terminal is the cooperative communication area, the first base station and the second base station is controlled to transmit a signal to the terminal,
And if the position of the terminal is any one of the region of the first base station or the region of the second base station, controlling the base station of the region where the terminal is located to transmit a signal to the terminal. A system for providing a cooperative communication service to a terminal in an environment including a cooperative communication region in which a first cell region by a first base station and a second cell region by a second base station overlap.
A signal information receiver configured to receive, from the first base station or the second base station, first signal information of a signal transmitted from the terminal to the first base station and second signal information of a signal transmitted to the second base station;
A terminal location storage unit for storing information on a previous location of the terminal together with terminal identification information about the terminal;
A timer for temporarily stopping the operating state by the control, resetting from the pause state to newly operate, changing the pause state to the operating state, and providing time information; And
Checking the terminal identification information from the first signal information and the second signal information to confirm the previous position information of the terminal stored in the terminal location storage, and receiving the signal included in the first signal information or the second signal information Terminal entry / exit determination unit for determining the entry / exit of the terminal into the cooperative communication area based on the strength information and the time information received from the timer.
Cooperative communication providing system comprising a. The method of claim 10,
Transmission state change indicating unit for requesting the signal transmission to the first base station or the second base station in order to change the signal transmission from the terminal entry / exit determination unit to the terminal whose location information is changed
Cooperative communication providing system comprising a. The method of claim 10,
The terminal entry / exit determination unit,
And controlling the change of the operation state with the timer, and transmitting and updating the location information on the terminal whose location has been changed to the terminal location storage unit. The method of claim 12,
The terminal entry / exit determination unit,
A first signal strength that is a signal strength received from the terminal by the first base station included in the first signal information, and a second signal strength that is received by the second base station included in the second signal information from the terminal; Calculate the difference in signal strength,
After determining the entry / exit into the cooperative communication area by comparing an entry threshold value for determining entry into the cooperative communication area previously set or an exit threshold value for determining entry in the cooperative communication area and the difference value,
And confirming whether the time information received from the timer exceeds a preset threshold time, and confirming entry / exit into the cooperative communication area when the threshold time is exceeded.

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