KR20150095510A

KR20150095510A - Method for measuring and reporting proximity of device to device

Info

Publication number: KR20150095510A
Application number: KR1020140016922A
Authority: KR
Inventors: 배형득; 신재욱; 송평중
Original assignee: 한국전자통신연구원
Priority date: 2014-02-13
Filing date: 2014-02-13
Publication date: 2015-08-21

Abstract

A D2D terminal calculates the reception signal intensity of a reference signal transmitted from a counterpart D2D terminal and a time difference between the reception point of the reference signal and the D2D transmission point of the D2D terminal; determines whether the condition of a preset report reference is satisfied based on the calculated reception signal intensity and time difference; and reports the reception signal intensity and the time difference to a base station, if the calculated reception signal intensity and time difference satisfy the condition of the report reference.

Description

[0001] METHOD FOR MEASURING AND REPORTING PROXIMITY OF DEVICE TO DEVICE [0002]

The present invention relates to a method for measuring and reporting proximity between terminals in direct communication between terminals.

In the direct-to-device (D2D) communication technology in the LTE / LTE-Advanced cellular mobile communication system, the D2D terminal performing the D2D communication establishes, releases and changes the D2D link under the control of the cellular network, Directly exchanges data between D2D terminals through the set D2D link.

This D2D communication technology improves the transmission speed of the cell boundary user without increasing the infrastructure cost, supports the cellular network connection to the D2D terminal in the shadow area, and aims at increasing the system capacity by reducing the interference.

The use of the uplink frequency band of LTE / LTE-A as a frequency band for D2D direct communication in 3GPP is being discussed. In the LTE / LTE-Advanced mobile communication system, the base station transmits a TAC (Timing Advance Command) to the UE, which controls the LTE uplink transmission timing of the UE. The TAC is a procedure for reducing uplink signal interference between terminals by allowing the uplink frames transmitted by the plurality of terminals to be received at the base station at the same time.

In the D2D direct communication, if the transmission time point at which the D2D terminal transmits the D2D signal is referred to as the D2D transmission point, the D2D transmission point of the D2D terminal connected to the cellular network is used as the LTE uplink transmission point. The reason for this is to reduce interference on cellular uplink communication due to D2D direct communication.

If the D2D terminal transmits a D2D channel using a D2D transmission time point (for example, an LTE downlink reception time point) different from the LTE uplink transmission time point, it overlaps with its own LTE uplink channel transmitted in an adjacent subframe Interference occurs with the LTE uplink channel of the adjacent D2D terminal. In order to prevent such interference, the D2D transmission time point of the D2D terminal is made equal to the LTE uplink transmission time point. However, in this case, the D2D terminal may differ from the D2D reception point of time when receiving the D2D signal transmitted from the relative D2D terminal, thereby causing interference due to the difference in the reception time point of the D2D signal in the D2D direct communication. This difference in reception time is because the propagation delay time between the D2D terminal and the relative D2D terminals is different and the D2D transmission time of the corresponding D2D terminals is different.

In a conventional LTE mobile communication system, a BS instructs a UE to measure a received signal strength of a serving cell and a neighboring cell, and the UE measures a received signal strength of a serving cell and a neighboring cell, and reports the received signal strength to the BS. At this time, the base station can set a report criterion such as periodic report or event report to the terminal, and the terminal reports the measurement result according to the instruction. In LTE / LTE-A, the received signal strength is RSRP (Reference Signal Received Power) and RSRQ (Reference Signal Received Quality), and measurement and reporting of the received signal strength is performed by a procedure necessary for handover to be.

In D2D direct communication measurements are proximity measurements between D2D terminals.

The D2D inter-terminal proximity measurement is used to estimate the communication channel environment between two D2D terminals when configuring the D2D bearer between D2D terminals. If the distance between two D2D terminals is too far away, the proximity measure is bad and the network can decide whether to establish a D2D bearer connection between two D2D terminals based on this proximity measurement.

The D2D inter-terminal proximity measurement is also used for service continuity of the already connected D2D bearer. If the proximity measurement falls below a certain threshold due to the moving distance between the D2D terminals, the network determines that the service through the established D2D connection is difficult and switches the D2D connection to the network connection to provide seamless service.

There are the following problems in applying the existing technology for the proximity measurement between D2D terminals. First, the proximity between D2D terminals can be measured at the D2D terminal performing D2D communication, and the base station can not know. Second, since the proximity measurement between the D2D terminals occurs between the D2D terminals, it is impossible for the base station to know the proximity measurement results without the help of the D2D terminal. Third, in the existing technology, only the received signal strength can be measured and the receiving time point of the D2D signal can not be measured.

Therefore, a separate method for realizing proximity measurement between D2D terminals in cellular mobile communication based D2D communication is needed.

A problem to be solved by the present invention is to provide a proximity measurement and reporting method between D2D terminals, which measures proximity between D2D terminals in a cellular mobile communication based D2D direct communication and reports proximity measurement results to a base station.

According to an embodiment of the present invention, a method of measuring and reporting the proximity between terminals in a D2D terminal performing D2D (Device-to-Device) communication is provided. A method for measuring and reporting a proximity measure between terminals includes calculating a time difference between a received signal strength of a reference signal transmitted from a relative D2D terminal and a reception timing of the D2D transmission point of the D2D terminal and a reception time of the reference signal, And reporting the received signal strength and the time difference to a base station if the received signal strength and the time difference satisfy a condition of the reporting criterion do.

According to the embodiment of the present invention, compared to the conventional method, not only the received signal strength of the D2D signal but also the difference between the transmission and reception time of the D2D signal is reported to the base station, so that the base station can utilize the D2D signal transmission / It is possible to identify a receiving terminal, thereby enabling identification of a terminal causing interference.

In addition, the connection between the D2D terminals having a very poor channel environment may not be established, and the service continuity of the already established D2D connection can be ensured, so that the degradation of the service quality of the D2D communication user can be reduced.

1 is a diagram illustrating a physical channel configuration for D2D communication according to an embodiment of the present invention.
2 is a diagram illustrating an example of a reception timing of a D2D terminal according to an embodiment of the present invention.
3 is a diagram illustrating a transmission position of a D2D reference signal in LTE-based D2D communication according to an embodiment of the present invention.
4 is a diagram schematically illustrating a method of measuring a difference value between a D2D transmission time point of a D2D terminal and a D2D reception time point of a relative D2D terminal according to an embodiment of the present invention.
5 is a diagram illustrating a method of measuring and reporting the proximity between terminals in the D2D communication based on the cellular mobile communication according to the embodiment of the present invention.
6 is a flowchart illustrating an event-based D2D proximity measurement reporting method of a D2D terminal according to an embodiment of the present invention.
7 is a diagram illustrating an apparatus for measuring proximity measurement of a D2D terminal according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out 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 order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification and claims, when a section is referred to as "including " an element, it is understood that it does not exclude other elements, but may include other elements, unless specifically stated otherwise.

Now, a method for measuring and reporting the proximity between terminals according to an embodiment of the present invention will be described in detail with reference to the drawings.

1 is a diagram illustrating a physical channel configuration for D2D communication according to an embodiment of the present invention.

Referring to FIG. 1, the UE1 is located within the cell coverage of the base station eNB1 and may be connected to the cellular network through the base station eNB1. And is connected between the UE1 and the eNB1 via a cellular physical channel.

The terminal UE2 is located within the cell coverage of the base station eNB2 and can be connected to the cellular network via the base station eNB2. And is connected between the UE2 and the eNB2 via a cellular physical channel.

The terminal UE3 may be located outside the cell coverage of the base stations eNB1 and eNB2.

At this time, the terminal UE2 can establish a D2D connection with the terminal UE1 and the terminal UE3 for D2D communication. The terminal UE2 is connected to the terminal UE1 and the terminal UE3 via a physical channel to perform D2D communication.

UEs UE1, UE2, and UE3 that perform D2D communication are called D2D terminals UE1, UE2, and UE3. The D2D terminals UE1, UE2, and UE3 set up, release, and change the D2D link under the control of (eNB1, eNB2), and directly transmit and receive data between the D2D terminals through the established D2D link. That is, the UEs UE1 and UE2 receive control directly from the base stations eNB1 and eNB2 such as D2D connection setup, measurement and power control, D2D transmission control and resource allocation, and the UE3 performs D2D connection setup, Control, D2D transmission / reception control and resource allocation indirectly from the base stations eNB1 and eNB2.

The UEs UE1, UE2, and UE3 measure the proximity information between the corresponding D2D terminals and report the proximity information measurement result to the base stations eNB1 and eNB2. The base stations eNB1 and eNB2 can perform control such as D2D connection setup, measurement and power control, D2D transmission / reception control and resource allocation based on the inter-terminal proximity measurement result. The relative D2D terminal can transmit the D2D reference signal for measurement of proximity information.

A D2D reference channel, a D2D shared data channel, and a D2D shared control channel are connected to the physical channels connected between the UEs UE2 and UE1 or UE2 and UE3, have.

The D2D reference channel is a non-contention based channel that is temporarily or periodically allocated to the UE. For example, a sounding reference signal may be transmitted to the D2D reference channel. The D2D reference channel can be dynamically allocated at the start of the D2D connection setup or when it is necessary to monitor the D2D radio link status and released when the D2D connection is terminated.

The D2D shared data channel is used to transmit data traffic between the UEs (UE2, UE1 or UE2, UE3) and is released when the D2D connection is terminated. In addition to data traffic, control messages may also be transmitted between the UEs (UE2, UE1 or UE2, UE3) via the D2D shared data channel.

The D2D shared control channel is used to directly transmit the control message between the UEs (UE2, UE1 or UE2, UE3) without going through the base station.

2 is a diagram illustrating an example of a reception timing of a D2D terminal according to an embodiment of the present invention.

As shown in Fig. 2, the D2D terminal UE2 has a D2D connection established with the D2D terminal UE1 and the D2D terminal UE3 for D2D communication, and the transmission time points of the D2D terminals UE1 and UE3 are respectively a And b, and it is assumed that the transmission time point of the D2D terminal UE2 is equal to f.

The D2D terminal UE2 can receive the D2D reference signal of the D2D terminal UE1 transmitted at the time point a and the D2D reference signal of the D2D terminal UE3 transmitted at the time point b at the time point c. In the D2D terminal UE2, a reception time difference e, which is a difference between the time point c and the time point d, occurs. The reception time difference e may be greater than the difference between transmission times of the D2D terminals UE1 and UE3. This is because the propagation delay time between the D2D terminals UE2 and UE3 is different from the propagation delay time of the D2D terminals UE2 and UE1 and the transmission time points of the D2D terminals UE1 and UE3 are also different. If the reception time difference is larger than a certain value, the signals of the D2D terminals UE1 and UE3 received by the D2D terminal UE2 cause mutual interference.

According to the embodiment of the present invention, the D2D terminal UE2 transmits proximity information not only to the received signal strength of the D2D reference signal but also to the D2D transmission timing of the D2D terminal UE2 and the D2D reference signal transmitted from the relative D2D terminals UE1 and UE3 The time difference value between the reception time points of the received signals.

3 is a diagram illustrating a transmission position of a D2D reference signal in LTE-based D2D communication according to an embodiment of the present invention.

Referring to FIG. 3, one radio frame (for example, Fn) includes a plurality of subframes SF1 to SF9, and each of the subframes SF1 to SF9 includes two slots SL1 and SL2. do.

The D2D reference signal (D2D RS) can be transmitted to the last symbol of the second slot (SL2) using the same kind of signal as the sounding reference signal of LTE.

4 is a diagram schematically illustrating a method of measuring a time difference value between a D2D terminal and a D2D terminal according to an embodiment of the present invention.

Referring to FIG. 4, the D2D terminal UE1 transmits a D2D RS to the last symbol of the second slot of the subframe SFn.

The D2D terminal UE1 receives the D2D RS transmitted from the D2D terminal UE1 at the time of receiving the B signal. At this time, if the transmission time of the D2D D2D terminal (UE2) is set to A, D2D terminal (UE2) calculates a difference value between A and B (T _d).

That is the difference value (T _d) refers to the time difference between the D2D transmission time point of the received point and the D2D terminal (UE2) receives the D2D RS in D2D terminal (UE2) sent from the external D2D terminal (UE1). At this time, the D2D transmission time point of the D2D terminal UE2 is set to be the same as the LTE uplink transmission time point of the D2D terminal UE2. The LTE uplink transmission time point of the D2D terminal UE2 indicates a time point of signal transmission from the D2D terminal UE2 to the base station.

5 is a diagram illustrating a method of measuring and reporting the proximity between terminals in the D2D communication based on the cellular mobile communication according to the embodiment of the present invention.

Referring to FIG. 5, the D2D terminal UE1 continuously or periodically transmits the D2D RS to the D2D terminal UE2 for a predetermined period of time (S510, S520).

D2D terminal (UE2) calculates the D2D terminal received signal strength and time difference (UE1) is transmitted a D2D RS (T _d) (S530). The time difference T _d is calculated as shown in Fig. The received signal strength may be Reference Signal Received Power (RSRP) or Reference Signal Received Quality (RSRQ).

D2D terminal (UE2) calculates the average value of received signal strength and time difference (T _d) calculated from the D2D RS transmitted continuously or periodically for the set time period (S530).

D2D terminal (UE2) is an average value of received signal strength and time difference (T _d) and L3 filtering (S540).

The D2D terminal UE2 compares the L3 filtered value with a report criterion preset by the base station eNB2 based on the L3 filtered value and if the L3 filtered value satisfies the condition of the report criterion in operation S550, format) to start the D2D proximity measurement report (S560). The D2D proximity measurement report includes received signal strength and time difference ( _Td ).

Here, the reporting criterion includes a criterion by which the D2D terminal UE2 judges the start of the proximity measurement report, and includes periodic reporting and event reporting. The reporting format also includes the objects and values to include in the proximity measurement report. Here, the object may be the received signal strength and time difference (T _d ).

If the reporting criterion is a periodic report, the D2D terminal UE2 periodically transmits the D2D proximity measurement report to the base station in accordance with the format.

On the other hand, if the report criterion is an event report, the D2D terminal UE2 sends an event D2D proximity measurement report to the base station according to the report format when the L3 filtered value satisfies the set reporting condition.

In the event-based D2D proximity measurement report of the UE2, an event generation condition may be set as follows.

First, the received signal strength measured by the D2D terminal UE2 may be smaller than the signal strength threshold value or the time difference T _d may be greater than the time threshold value. The entry condition for this event can be set as shown in Equation (1), and the departure condition can be set as shown in Equation (2).

In Equations (1) and (2), M _d represents the received signal strength measured at the D2D terminal UE2, and T _d represents the time difference value measured at the D2D terminal UE2. Thresh1 is the signal strength threshold for the event, and Thresh2 is the time threshold for the event. M _d is expressed in dBm for RSRP or in dB for RSRQ. T _d is expressed in microseconds. Thresh1 is expressed in the same unit as M _d . Thresh2 is expressed in the same unit as T _d . alpha and beta are arbitrary offset values.

Second, the event may be generated when the received signal strength of the D2D terminal UE2 is lower than the signal strength threshold value. The entry condition for this event is set as shown in Equation (3), and the departure condition can be set as shown in Equation (4).

Third, an event may occur when the time difference T _d is greater than the time threshold value. The entry condition for this event is set as shown in Equation (5), and the departure condition can be set as shown in Equation (6).

6 is a flowchart illustrating an event-based D2D proximity measurement reporting method of a D2D terminal according to an embodiment of the present invention. FIG. 6 shows a method of reporting the D2D proximity measurement for the first event described above.

Referring to Figure 6, D2D terminal (UE2) calculates the RSRP as the time difference (T _d) which corresponds to the received signal strength of one RS D2D the transmission terminal (UE1) (S602). At this time, the calculated RSRP as the time difference (T _d) may be a value of the RSRP and the average time difference (T _d) measured from the D2D RS transmitted continuously or periodically for the set time period.

The D2D terminal UE2 L3 filters the time difference T _d with RSRP (S604).

D2D terminal (UE2) is compared to the signal strength threshold (Thresh1) report set in relative to the RSRP, and compared to the time threshold (Thresh2) set in the report based on the time difference (T _d) (S606).

D2D terminal (UE2) is RSRP is less than or equal to the signal strength threshold (Thresh1), T _d is greater than the time threshold (Thresh2), and sets the entry as an event condition (S608).

The D2D terminal UE2 determines whether the event entry state continues for the set time (S610).

The D2D terminal UE2 starts reporting an event occurrence to the base station eNB2 when the event entry state continues for a preset time period (S612). The event occurrence report is a proximity measurement report and may include RSRP and T _d calculated according to the reporting format.

On the other hand, D2D terminal (UE2) is the RSRP or more signal strength thresholds (Thresh1), it is determined whether T is less than _d threshold time (Thresh2) (S614).

D2D terminal (UE2) is RSRP the signal strength threshold (Thresh1) or more and, if T _d is less than the time threshold value (Thresh2), and sets the event exit condition (S616).

The D2D terminal UE2 determines whether the event disparity state continues for a set time (S618).

The D2D terminal UE2 starts the event deviation report to the base station eNB2 when the event deviation state continues for the set time (S620).

7 is a diagram illustrating an apparatus for measuring proximity measurement of a D2D terminal according to an embodiment of the present invention. In FIG. 7, the D2D terminal UE2 is referred to for convenience.

7, the proximity measurement report apparatus 700 of the D2D terminal UE2 includes a measurement unit 710, a filtering unit 720, a determination unit 730, and a reporting unit 740. [

The measuring unit 710 measures the received signal strength and the time difference T _d from the D2D RS signal transmitted by the relative D2D terminal continuously or periodically. The received signal strength and time difference (T _d ) may be an average value of the RSRP and the time difference (T _d ) measured from the D2D RS transmitted continuously or periodically for the set period.

The filtering unit 720 L3 filters the received signal strength and the time difference T _d .

The determination unit 730 determines whether the received signal strength and the time difference T _d satisfy the conditions of the reporting criterion.

The report unit 740 generates a report message according to the set report format and transmits the report message to the base station eNB2 when the received signal strength and the time difference T _d satisfy the conditions of the report criterion. The report message may include received signal strength and time difference (T _d ).

In this way, the base station eNB2 can receive and report the inter-terminal proximity information in the D2D communication, and can control connection establishment, release, change, etc., between the D2D terminals from the reported proximity information.

The embodiments of the present invention are not limited to the above-described apparatuses and / or methods, but may be implemented through a program for realizing functions corresponding to the configuration of the embodiment of the present invention or a recording medium on which the program is recorded, Such an embodiment can be readily implemented by those skilled in the art from the description of the embodiments described above.

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

A method for measuring and reporting the proximity between terminals in a D2D terminal performing D2D (Device-to-Device) communication,
Calculating a time difference between a reception signal strength of the reference signal transmitted from the relative D2D terminal and a reception time of the D2D transmission terminal and the reference signal of the D2D terminal,
Determining whether the condition of the reporting criterion is satisfied based on the received signal strength and the time difference, and
Reporting the received signal strength and the time difference to a base station if the received signal strength and the time difference satisfy a condition of the reporting criteria;
Terminal proximity measurement and reporting method.