KR100826629B1 - Method for Link Synchronization Using Received Power in RF Repeater - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a link synchronization method of an RF repeater using received power.

2. The technical problem to be solved by the invention

The present invention provides a link synchronization method of an RF repeater for link link switching at an accurate time point by measuring and accumulating a received power for a predetermined time interval at a predetermined period, comparing with a reference level and detecting a link termination time point. There is a purpose.

3. Summary of Solution to Invention

The present invention provides a link synchronization method of an RF repeater using received signal power, comprising: an initial link path setting step of setting an initial link path; A received signal power measuring step of measuring received signal power in a set initial link path; A received power accumulation step of accumulating the received signal power for a predetermined time at a predetermined period when the received signal power is detected; A reference level setting step of setting a reference level for link switching based on the accumulated received signal power; A link end point detection step of detecting an end point of the link by finding an edge point of the accumulated detected received power waveform based on the set reference level; And a link path switching step of switching the link path using the detected link termination time point.

4. Important uses of the invention                 

The present invention is used in orthogonal frequency division multiplexing / time division duplex (OFDMA / TDD) systems.

Time Division Duplex, Repeater, Link Sync, Receive Power

Description

Method for Link Synchronization Using Received Power in RF Repeater}             

1 is a flowchart illustrating an embodiment of a link path synchronization method using received power according to the present invention;

2 is a temporary flowchart illustrating a method of switching a link path from a downlink path to an uplink path according to the present invention;

3 is an embodiment diagram illustrating a method of taking a cumulative operation of received power;

4 is a temporary flowchart illustrating a method of switching a link path from an uplink path to a downlink path according to the present invention;

FIG. 5 is a diagram illustrating a measurable power section when receiving power is detected in an uplink / downlink path;

6 is a flowchart illustrating a method of detecting a link termination time point.

The present invention relates to a link synchronization method of an RF repeater, and more particularly, to a link synchronization method using received power in a TDD (Time Division Duplex) type RF repeater.

Recently, a wireless communication system capable of transmitting and receiving data at high speed wirelessly has been developed. In such a wireless communication system, a repeater is used to connect a wireless terminal and a base station in a shaded area.

In this case, in the wireless communication system, the same frequency band is used as a reverse channel (a base station to a base station) channel and a forward channel (a base station to a wireless terminal) channel, and a time division duplex for distributing the reverse channel and the forward channel in time. TDD) method. Therefore, in the repeater, the link path switching should be performed at the correct time.

In general, a frame synchronization method in an orthogonal frequency division multiple access (OFDMA) system includes a method using a correlation of a cyclic prefix (CP) section, a method using a correlation between a preamble section, a pilot pattern detection method, and the like.

All of these schemes can be used as a link path synchronization method of a TDD repeater. However, when the pilot pattern detection method is used, since a demodulator must be implemented in the TDD repeater, it is inefficient because it increases the complexity of the system and requires a high cost. Therefore, methods using a correlation between the CP section and the preamble section may be applied.

However, when using the method using the correlation between the CP section and the preamble section as the link path synchronization method of the TDD repeater, since the level variation of the correlation value may seriously occur due to the characteristics on the radio channel, a separate correlation level is required. There is a problem that the signal processing of.

In addition, when using the method using the correlation between the CP section and the preamble section as the link path synchronization method of the TDD repeater, the start time and the end time of the downlink can be known accurately, but the end time of the uplink is the TTG and the downlink. Since it calculates using only the ratio of, there is a problem that an undesired switching time delay occurs when switching from the RF repeater to the downlink.

The present invention has been proposed to solve the above problems, by measuring and accumulating the received power for a certain period of time in a certain period to compare with the reference level and to detect the end point of the link, so that the link path switching at the correct time, It is an object of the present invention to provide a link synchronization method of an RF repeater.

Other objects and advantages of the present invention can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. Also, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

In order to achieve the above object, the present invention provides a link synchronization method of an RF repeater using received signal power, comprising: an initial link path setting step of setting an initial link path; A received signal power measuring step of measuring received signal power in a set initial link path; A received power accumulation step of accumulating the received signal power for a predetermined time at a predetermined period when the received signal power is detected; A reference level setting step of setting a reference level for link switching based on the accumulated received signal power; A link end point detection step of detecting an end point of the link by finding an edge point of the accumulated detected received power waveform based on the set reference level; And a link path switching step of switching the link path by using the detected link termination time point.

In addition, the present invention, the repeater having a processor, the initial link path setting function for setting the initial link path; A received signal power measurement function for measuring received signal power in a set initial link path; A received power accumulation function that accumulates the received signal power for a predetermined time at a predetermined period when the received signal power is detected; A reference level setting function for setting a reference level for link switching based on accumulated received signal power; A link end point detection function for detecting an end point of a link by finding an edge point of a cumulatively detected received power waveform based on a set reference level; And a computer readable recording medium having recorded thereon a program for realizing a link path switching function for switching the link path using the detected link termination time point.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, whereby those skilled in the art may easily implement the technical idea of the present invention. There will be. In addition, in describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a flowchart illustrating an embodiment of a link path synchronization method using received power according to the present invention.

As shown, first, the repeater sets an initial link path as a downlink path (D / L: down link) (110).

Thereafter, the downlink termination point is detected using the received power (120), and a time delay for changing the link path is set (130) according to the situation.

Next, in consideration of the guard time, the repeater converts the initially set downlink path to the uplink path (140), and detects an uplink end time in the same manner as the downlink termination detection (150).

In addition, in accordance with a situation, a time delay for changing the link path is provided to delay the switching time point from the uplink path to the downlink path (160).

Thereafter, in consideration of the guard time, the repeater converts the uplink path (U / L: Up Link) into the downlink path (170).                     

The above process is repeated until the power of the repeater is turned off.

Meanwhile, in order to apply the link path synchronization method using the received power according to the present invention, first, a threshold level for detecting an uplink / downlink end point should be set.

That is, when the repeater detects the received power. Even if the link environment between the base station and the repeater is in the line of sight state, the envelope change of the received signal power may be severely affected by the field loss and fading (rician / rayleigh) effects depending on the distance. In order to distinguish the up / down link termination time through the detection of the received power, a certain criterion should be set.

FIG. 2 is a temporary flowchart illustrating a method of switching a link path from a downlink path to an uplink path according to the present invention, and FIG. 3 is a diagram illustrating a method of taking a cumulative operation of received power.

As shown in FIG. 2, first, the repeater sets an initial link path as a downlink path (210) and measures reception power on the downlink path (220). In this case, the reference numeral 210 may be a state in which the downlink path is switched from the uplink path instead of the initial link path setting.

When the received power on the downlink path is not detected, that is, when the base station is inactivated, the initial link path is maintained.

When the received power on the downlink path is detected, i.e., when the base station is activated, during the constant power measurement interval T_p at one frame interval T_f as shown in FIG. 3 to attenuate the variation in the detected received power level. The received power is accumulated (230). At this time, in order to reduce the change of the envelope due to the radio channel characteristic when the reception power is detected, the reception power is detected only for a predetermined time interval based on the on-time of the repeater.

Next, a reference level for the accumulated received power value is set (240).

Thereafter, the downlink termination time is detected based on the reference level (250), and a time delay for changing the link path is delayed according to a situation to delay the switching time from the downlink path to the uplink path (260).

Finally, in consideration of the protection time, the path is switched from the downlink path to the uplink path (270).

4 is a temporary flowchart illustrating a method of switching a link path from an uplink path to a downlink path according to the present invention.

As shown in FIG. 4, first, in a state in which the link path is switched to the uplink path (410), the repeater measures the power of the received signal (420).

When the received signal power is not detected, that is, when there is no wireless terminal in the service area, the end point of the uplink path is detected by using the TTG section, which is a guard period, and a fixed uplink ratio, based on the downlink end point. (430). In this case, the uplink / downlink ratio and the guard interval ratio are preset values.                     

Thereafter, depending on the situation, a time delay for changing the link path is provided to delay the switching time point from the uplink path to the downlink path (440).

Thereafter, the path is switched from the uplink path to the downlink path (450).

When the received signal power is detected, that is, when there is a wireless terminal in the service area, the received power is accumulated for a constant power measurement interval T_p at one frame interval T_f to set a reference level for link path switching. (460). At this time, in order to reduce the change of the envelope due to the radio channel characteristic when the reception power is detected, the reception power is detected only for a predetermined time interval based on the on-time of the repeater.

Next, a reference level for the accumulated received power value is set (470).

Thereafter, the uplink termination time is detected based on the reference level and the downlink termination time (480), and a time delay for changing the link path is delayed according to a situation to delay the switching time from the uplink path to the downlink path. (440).

Finally, the path is switched from the uplink path to the downlink path (450).

FIG. 5 is a diagram illustrating a measurable power section when detecting received power in an uplink / downlink path, and FIG. 6 is a flowchart illustrating a method of detecting a link termination point.

5 (a) shows a power section in the downlink path measurable by the repeater when the base station is activated. Reference numeral ① denotes a case in which the accumulated power waveform values are higher than or equal to the reference level in all sections, and reference numerals ②, ③, and ④ denotes a case in which the accumulated power waveform values are not higher than or equal to the reference level in all sections.

FIG. 5B illustrates a power section in an uplink path that can be measured by the repeater when the wireless terminal exists in the repeater service area. Reference numeral ⑦ denotes a case where the accumulated power waveform value is higher than or equal to the reference level in all sections, and reference numerals ⑤, ⑥, and ⑧ denotes cases where the accumulated power waveform values are not higher than or equal to the reference level in all sections.

As shown in FIG. 6, in order to detect the end point of a link, first, a reception is performed during a constant power measurement interval T_p at one frame interval T_f based on the relay on-time or the downlink end time. The power is accumulated N times (610).

It is determined whether the accumulated power waveform value is greater than or equal to the reference level in all sections (620).

If the accumulated power waveform value is greater than or equal to the reference level in all sections, that is, in the case of reference numerals 1 and ⑦ of FIG. 5, the power measurement section is moved to the right (630). It is determined whether the reference level or more in the interval (610, 620).

When the accumulated power waveform value is less than or equal to the reference level in all sections, that is, in the case of reference numerals ②, ③, ④, ⑤, ⑥ and ⑧ of FIG. 5, it is determined whether the accumulated power waveform value is less than or equal to the reference level in all sections. (640).

When the accumulated power waveform value is less than or equal to the reference level in all sections, that is, in the case of reference numerals 3 and ⑤ of FIG. 5, the power measurement section is moved to the left (650), and starts again from the reference numeral 610.                     

Meanwhile, when the accumulated power waveform value is not below the reference level in all sections but below the reference level in only some sections, that is, in the case of reference numerals ②, ④, ⑥, and ⑧ of FIG. 5, the falling edge of the accumulated power waveform is detected. It is determined whether this is possible (660).

When the falling edge of the accumulated power waveform is not detected, that is, in the case of reference numerals ④ and ⑥ of FIG. 5, the power measurement section is shifted to the right and starts again from the reference numeral 610.

When the falling edge of the accumulated power waveform is detected, that is, in the case of reference numerals 2 and 8 of FIG. 5, the up / down link end time is detected (670).

On the other hand, as described above, in the present embodiment has been described by limiting the initial configuration link path to the downlink path at the time of the on-time of the repeater, in the present invention by using the initial configuration link path as an uplink path Obviously, the link synchronization method can be implemented.

As described above, the method of the present invention may be implemented as a program and stored in a recording medium (CD-ROM, RAM, ROM, floppy disk, hard disk, magneto-optical disk, etc.) in a computer-readable form. Since this process can be easily implemented by those skilled in the art will not be described in more detail.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by the drawings.

As described above, the present invention has an effect of enabling smooth and reliable data transmission by accurately switching uplink / downlink paths when using a TDD repeater.

In addition, the present invention has the effect of not need to accumulate the measurement power of all the frames because it performs the measurement and cumulative calculation of the received power of only a certain time interval for link path synchronization.

Claims (9)

In the link synchronization method of the RF repeater using the received signal power, An initial link path setting step of setting an initial link path; A received signal power measuring step of measuring received signal power in a set initial link path; A received power accumulation step of accumulating the received signal power for a predetermined time at a predetermined period when the received signal power is detected; A reference level setting step of setting a reference level for link switching based on the accumulated received signal power; A link end point detection step of detecting an end point of the link by finding an edge point of the accumulated detected received power waveform based on the set reference level; And Link path switching step of switching the link path using the detected link termination time point Link synchronization method of the RF repeater comprising a. The method of claim 1, The initial link path is Downlink path, Initial link path maintenance step, if the received signal power is not measured, to maintain the initial setup path Link synchronization method of the RF repeater further comprising. The method of claim 2, An uplink received power measurement step of measuring received signal power of the switched uplink path; An uplink received power accumulating step of accumulating received signal power for a predetermined time at a predetermined period when the received signal power is detected in the uplink received power measuring step; A second reference level setting step of setting a reference level for link switching based on the accumulated received signal power; An uplink termination point detection step of detecting an uplink termination point by finding an edge point of the cumulatively detected received power waveform based on the set second reference level and the downlink termination point; And A second link path switching step of switching the link path using the detected uplink termination point; Link synchronization method of the RF repeater further comprising. The method of claim 3, wherein If the received signal power is not detected in the uplink reception power measurement step, an uplink termination time calculation step of calculating an uplink termination time using a preset protection time and uplink path ratio based on the downlink termination time Link synchronization method of the RF repeater further comprising. The method of claim 4, wherein Link end time detection step, Receiving power is accumulated for a predetermined time at regular intervals based on the on-time, and shifting the receiving power detection time until the falling edge of the accumulated waveform is detected based on the set reference level. Link synchronization method of an RF repeater characterized in that. The method according to any one of claims 1 to 5, Time delay insertion step of inserting a time offset before switching the link path Link synchronization method of the RF repeater further comprising. In a repeater with a processor, An initial link path setting function for setting an initial link path; A received signal power measurement function for measuring received signal power in a set initial link path; A received power accumulation function that accumulates the received signal power for a predetermined time at a predetermined period when the received signal power is detected; A reference level setting function for setting a reference level for link switching based on accumulated received signal power; A link end point detection function for detecting an end point of a link by finding an edge point of a cumulatively detected received power waveform based on a set reference level; And Link path switching function to switch the link path using the detected link termination time point A computer-readable recording medium having recorded thereon a program for realizing this. The method of claim 1, The initial link path is Downlink path, Initial link path hold function maintains the initial set path when no received signal power is measured A computer-readable recording medium that records a program for further realization. The method of claim 8, An uplink received power measurement function for measuring received signal power of the switched uplink path; An uplink received power accumulation function that accumulates received signal power for a predetermined time at a predetermined period when the received signal power is detected in the uplink received power measurement step; A second reference level setting function for setting a reference level for link switching based on accumulated received signal power; An uplink termination point detection function for detecting an uplink termination point by finding an edge point of the cumulatively detected received power waveform based on the set second reference level and the downlink termination point; And A second link path switching function for switching the link path using the detected uplink termination point; A computer-readable recording medium that records a program for further realization.

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