KR20130021832A - Method and apparatus for adjusting timing in communication system - Google Patents

Abstract

PURPOSE: A timing control method in a communication system and a device thereof are provided to increase accuracy of timing estimation in a base station. CONSTITUTION: A memory(330) stores cyclic shifts(CS) assigned in accessed terminals. A timing detection unit determines detection areas of the CS corresponding to intervals of the CS and the number of terminals. The timing detection unit detects sounding reference signals(SRS) of the terminals in the detection areas. A control unit(320) controls the timing of the terminals corresponding to intervals of the SRS and the CS in the detection areas. [Reference numerals] (310) Wireless communication unit; (320) Control unit; (330) Memory

Description

METHOD AND APPARATUS FOR ADJUSTING TIMING IN COMMUNICATION SYSTEM}

The present invention relates to a communication method and apparatus in a communication system, and more particularly, to a timing adjustment method and apparatus in a communication system.

In general, a communication system provides various kinds of communication services such as voice or data. In such a communication system, a base station controls data transmission and reception corresponding to a plurality of terminals. That is, the base station performs scheduling for downlink (DL) and uplink (UL), and allocates resources for data transmission and reception to each terminal. At this time, the base station performs scheduling for uplink according to the uplink state identified by each terminal. For example, in a Long Term Evolution (LTE) system, a base station receives a sounding reference signal (SRS) at each terminal and uses it to determine an uplink state. Here, the base station can perform channel estimation and timing estimation through the sounding reference signal. That is, the base station allocates a different cyclic shift code (CS) for each terminal, detects a peak sample in a predetermined detection area around each CS, and estimates timing.

However, in the above communication system, the farther the distance between the base station and the terminal, the larger the timing gap between the base station and the terminal. At this time, if the timing gap is large, the base station may not detect the peak sample in the detection area for the terminal. As a result, it is difficult to estimate timing at the base station.

Accordingly, it is an object of the present invention to improve the accuracy for estimating timing at a base station. That is, the present invention is to variably determine the detection area in the base station.

The timing adjustment method of the base station in the communication system according to the present invention for solving the problem, the process of allocating CS to each of the connected terminals, and corresponding to the CS according to the number of the terminal and the interval of the CS Determining detection areas, detecting SRSs of the terminals in the detection areas, and adjusting timing with the terminal according to an interval between the CS and the SRS in each of the detection areas. It is done.

In addition, the timing adjustment apparatus of the base station in the communication system according to the present invention for solving the above problems, the memory for storing corresponding to each of the CS assigned to the connected terminals, the number of the terminals and the interval between the CS Determining detection areas corresponding to the CSs and adjusting a timing with the terminal according to an interval between the CS and the SRS in each of the detection areas, and a timing detector for detecting the SRSs of the terminals in the detection areas. It characterized in that it comprises a control unit for.

According to the timing adjustment method and apparatus in the communication terminal of the present invention, the base station can variably determine the detection area for estimating the timing of the terminal. Therefore, even if the timing gap between the base station and the terminal increases, the base station can efficiently detect the timing of the terminal. Accordingly, the accuracy of estimating timing at the base station can be further improved.

1 is a conceptual diagram illustrating a structure of a general communication system;
2 is a flowchart illustrating a communication procedure in a general communication system;
3 is a conceptual diagram illustrating a radio frame structure of a general communication system;
4 is a conceptual diagram illustrating a slot structure in FIG. 3;
5 is a conceptual diagram illustrating a subframe structure used for downlink in a general communication system;
6 is a conceptual diagram illustrating a subframe structure used for uplink in a general communication system;
7 is a conceptual diagram illustrating a CS allocation structure in a general communication system;
8 is a conceptual diagram illustrating a general detection area determination method;
9 is a block diagram showing an internal configuration of a timing adjustment device in a base station according to an embodiment of the present invention;
10 is a block diagram illustrating a detailed configuration of a control unit in FIG. 9;
11 is a flowchart illustrating a timing adjustment procedure in a base station according to an embodiment of the present invention;
12 is a flowchart illustrating a timing adjusting method in FIG. 11;
FIG. 13 is an exemplary diagram for describing an example of a detection region determination method in FIG. 11; and
14 is an exemplary diagram for describing another example of the detection area determination method in FIG. 11.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this case, the same components in the accompanying drawings should be noted that the same reference numerals as possible. And a detailed description of known functions and configurations that can blur the gist of the present invention will be omitted.

1 is a conceptual diagram showing the structure of a general communication system.

Referring to FIG. 1, a communication system includes a user equipment (UE) 110 and a base station (BS) 120 that provides a communication service to the terminals 110. The terminal 110 may be fixed or mobile. The terminal 110 connects to the base station 120 to transmit and receive data. The base station 120 controls data transmission and reception corresponding to the terminals 110. That is, the base station 120 performs scheduling for downlink and uplink, and allocates resources for data transmission and reception to each terminal 110.

2 is a flowchart illustrating a communication procedure in a general communication system.

Referring to FIG. 2, in step 211, the terminal 110 transmits a random access channel message (RACH preamble) to the base station 120. At this time, the terminal 110 requests resource allocation to the base station 120 through a random access request message. In step 213, the base station 120 transmits a random access response message to the terminal 110. That is, when the terminal 110 receives the random access request message, the base station 120 performs scheduling to allocate resources for the terminal 110.

Next, the terminal 110 transmits an RRC connection request message to the base station 120 in step 215. At this time, the terminal 110 transmits an RRC connection request message by using the resources allocated by the base station 120. In step 217, the base station 120 transmits an RRC connection setup message to the terminal 110. At this time, the base station 120 transmits the SRS configuration information. Here, the SRS configuration information includes bandwidth, SRS sequence, transmission period and frequency information of the SRS transmission region. In addition, the terminal 110 transmits the SRS to the base station 120 in step 219. At this time, the terminal 110 transmits the SRS by using the SRS configuration information.

3 is a conceptual diagram illustrating a radio frame structure of a general communication system.

3, a radio frame (radio frame) is comprised of 10 subframes (subframe) made of a uniform size having a length of 10 ms (327200 o T _S). Each subframe has a length of 1 ms and consists of two slots. Each slot has a length of 0.5 ms (15360 T _S ). Here, T _S represents a sampling time and may be expressed as T _S = 1 / (15 ㅧ 2048) = 3.2552 ㅧ 10 ⁻⁸ ≒ 33 ns. Each slot consists of a plurality of symbols in the time domain and a plurality of resource blocks (RBs) in the frequency domain. At this time, in each slot, the number of resource blocks is determined according to the transmission bandwidth (bandwidth). For example, in an LTE system, each slot may consist of six or seven symbols, and each resource block may consist of twelve tones.

4 is a conceptual diagram illustrating a slot structure in FIG. 3.

Referring to FIG. 4, a slot consists of a plurality of symbols in the time domain and a plurality of resource blocks in the frequency domain. As each resource block consists of 12 tones, each slot may consist of N ^DL ㅧ 12 tones in the frequency domain. Each slot may consist of six or seven symbols. However, the number of tones and the number of symbols in each slot can be changed. For example, the number of symbols in each slot may vary depending on the length of the cyclic prefix (CP). In addition, each slot is composed of a plurality of resource elements (REs), and resource elements are formed by tones and symbols. That is, the resource element is formed by one tone and one symbol, and is indicated by the index of the tone and the index of the symbol. In this way, in one slot, one resource block is composed of 12 ㅧ 7 resource elements.

5 is a conceptual diagram illustrating a subframe structure used for downlink in a general communication system.

Referring to FIG. 5, a downlink subframe includes a plurality of Orthogonal Frequency Division Multiplexing (OFDM) symbols. For example, a downlink subframe consists of 12 or 14 OFDM symbols. At this time, in the downlink subframe, a part of the OFDM symbols disposed at the front end is used as the control region, and the rest of the OFDM symbols are used as the data region. Here, the number of OFDM symbols for the control region may be set independently for each subframe. The control region is used to transmit scheduling information and other L1 / L2 (Layer 1 / Layer 2) control information. Such a control region includes a physical control format indicator channel (PCFICH), a physical hybrid-automatic repeat request (HARQ) indicator channel (PHICH), and a physical downlink control channel (PDCCH). The data area is used to carry traffic. This data area includes a Physical Downlink Shared Channel (PDSCH).

6 is a conceptual diagram illustrating a subframe structure used for uplink in a general communication system.

Referring to FIG. 6, the uplink subframe includes a plurality of SC-FDMA symbols. For example, an uplink subframe consists of 12 or 14 SC-FDMA symbols. In this case, the uplink subframe is divided into a control region and a data region. The control region is used for transmitting downlink status information, downlink reception ACK / NACK, uplink scheduling request, and the like in the terminal. This control region includes a Physical Uplink Control Channel (PUCCH). The data area is used to transmit data in the terminal. This data area includes a PUSCH (Physical Uplink Shared Channel). At this time, in the data area, any one of the SC-FDMA symbols arranged at the end is used to transmit the SRS in the terminal.

At this time, in each resource block, the SRS is divided into two comb types. Here, the SRSs are classified according to the indexes of tones arranged in corresponding SC-FDMA symbols. That is, if the tone index is even, the SRS is classified into an even comb type, and if the tone index is odd, the SRS is classified into an odd comb type. In addition, multiplexing for 16 terminals is possible in each resource block. On the other hand, there are eight CSs in each comb type. That is, each resource block is used to transmit SRSs in up to eight terminals.

7 is a conceptual diagram illustrating a CS allocation structure in a general communication system.

Referring to FIG. 7, at least one of CS0, CS2, CS4, CS6, CS8, CS10, CS12, and CS14 is allocated to at least one terminal in each resource block. That is, the base station configures an SRS sequence for the terminal to transmit the SRS in CS0, CS2, CS4, CS6, CS8, CS10, CS12, or CS14, and transmits the SRS configuration information to the terminal. And CS1, CS3, CS5, CS7, CS9, CS11, CS13, and CS15 correspond to any two center points adjacent to each other in CS0, CS2, CS4, CS6, CS8, CS10, CS12, and CS14, respectively. It is used to determine the detection region corresponding to each of CS2, CS4, CS6, CS8, CS10, CS12, and CS14. Here, 128 samples are arranged between any two adjacent ones in CS0, CS1, CS2, CS3, CS4, CS5, CS6, CS7, CS8, CS9, CS10, CS11, CS12, CS13, CS14, and CS15.

8 is a conceptual diagram illustrating a general detection area determination method.

Referring to FIG. 8, as the SRS is configured to be transmitted in tones of even or odd indexes in each resource block, detection regions corresponding to CS0, CS2, CS4, CS6, CS8, CS10, CS12, and CS14, respectively. Is determined to correspond to wh 64 samples on each basis. For example, corresponding to the terminal to which CS0 is assigned, the base station determines the detection area in the interval of the center point between CS15 and CS0 and the center point between CS0 and CS1. The base station detects the SRS for the terminal in the corresponding detection area and estimates the timing of the terminal. However, when the timing of the terminal is delayed or advanced to exceed 64 samples, the base station cannot estimate the timing of the terminal in the corresponding detection area.

9 is a block diagram showing an internal configuration of a timing adjustment device in a base station according to an embodiment of the present invention. 10 is a block diagram illustrating a detailed configuration of a controller in FIG. 9.

Referring to FIG. 9, in the present embodiment, the timing adjusting device of the base station 300 includes a wireless communication unit 310, a control unit 320, and a memory 330.

The wireless communication unit 310 performs a wireless communication function of the base station 300. The wireless communication unit 310 includes a transmitter for up-converting a frequency of a transmitted signal to a transmission band, and a receiver for down-converting a frequency of a received signal to a base band.

The controller 320 performs a function of controlling the overall operation of the base station 300. The controller 320 allocates CSs to terminals connected to the base station 300, respectively. The controller 320 includes a data processor including a transmitter for encoding and modulating transmitted data and a receiver for demodulating and decoding a received signal. Here, the data processing unit may be composed of a modem and a codec.

10, the control unit 320 includes a fast fourier transformer (FFT) 321, a sequence combiner 323, an inverse discrete fourier transformer (325), a cyclic shift unit 327, and a timing detector 329. ). FFT 321 applies a Fast Fourier Transform to the received data. The sequence combiner 323 multiplies the data output from the FFT 321 by the SRS sequence. The IDFT 325 applies an inverse discrete Fourier transform to the data output from the sequence combiner 323. The circular movement unit 327 restores the circular movement of the data output from the IDFT 325. That is, the circular movement unit 327 restores the circular movement corresponding to the CSs assigned to the terminals. The timing detector 329 determines detection areas corresponding to the CSs according to the number of terminals and the interval of the CSs according to an exemplary embodiment of the present invention. In addition, the timing detector 329 detects SRSs of terminals in the detection areas, and estimates timing. In addition, the controller 320 adjusts the timing with the terminal according to the interval between the CS and the SRS in each of the detection areas.

The memory 330 is composed of a program memory and data memories. The program memory stores programs for controlling the general operation of the base station 300. At this time, the program memory stores programs for adjusting timing according to an embodiment of the present invention. The data memory stores data generated while executing programs. The memory 330 stores corresponding CSs respectively assigned to terminals according to an exemplary embodiment of the present invention.

11 is a flowchart illustrating a timing adjustment procedure in a base station according to an embodiment of the present invention. FIG. 13 is an exemplary view for explaining an example of a detection area determination method in FIG. 11, and FIG. 14 is an exemplary view for explaining another example of the detection area determination method in FIG. 11.

Referring to FIG. 11, in the present embodiment, the timing adjustment procedure of the base station 300 starts from the control unit 320 assigning CSs to terminals connected to the base station 300 in step 411.

Next, when the SRS is received, the control unit 320 detects this in step 413 and determines the detection area for detecting the SRS in step 415. In this case, the controller 320 determines detection areas corresponding to the CSs according to the number of terminals and the intervals of the CSs. The controller 320 determines the detection areas based on the CSs allocated to the terminals. Here, the controller 320 may determine detection areas corresponding to the CSs based on the center points of two adjacent intervals in the CSs allocated to the terminals.

For example, a terminal corresponding to index 0, that is, a terminal 0 (UE0) and a terminal corresponding to index 1, that is, terminal 1 (UE1) is connected to the base station 300, CS0 is assigned to UE0, and CS4 is assigned to UE1. Assume that is assigned. In this case, the controller 320 may determine the detection area corresponding to CS0 according to the interval of CS2 corresponding to the center point between CS0 and CS4. In this case, as illustrated in FIG. 13, the controller 320 may determine a preceding section corresponding to CS14 and CS0 as a detection region corresponding to CS0 at intervals corresponding to the delay section and the delay section corresponding to CS0 and CS2. Alternatively, the controller 320 may determine a detection area corresponding to CS4 according to the interval of CS4 from CS2 corresponding to the center point between CS0 and CS4. Here, as illustrated in FIG. 14, the controller 320 may determine a delay section corresponding to CS4 and CS6 as a detection region corresponding to CS4 in a size corresponding to the preceding section and the preceding section corresponding to CS2 and CS4.

Meanwhile, as illustrated in FIG. 14, the controller 320 may determine a detection area by applying a preset delay offset corresponding to CS4. That is, the controller 320 may determine the detection area corresponding to CS4 by applying intervals corresponding to the delay section and the preceding section, respectively, based on the point where the delay offset is applied to CS4. Meanwhile, as illustrated in FIG. 14, the controller 320 may manage the detection area corresponding to CS0 as a delay section, an on time section, and a preceding section. That is, the controller 320 may set the time intervals at predetermined intervals in the detection area corresponding to CS4.

Next, the controller 320 detects a peak sample in the detection area in step 417. That is, the controller 320 detects any one of the maximum received strengths of the samples corresponding to each detection area corresponding to the CSs assigned to the terminals. At this time, the controller 320 estimates the peak sample at the timing of the actual SRS. In operation 419, the controller 320 detects a timing offset according to the interval between the CS and the peak sample. That is, the controller 320 detects the timing offset according to the delay or the degree of precedence of the peak sample corresponding to each of the CSs assigned to the terminals.

For example, if the peak sample corresponds to a position delayed by 10 samples from CS4 in the detection region corresponding to CS4, the controller 320 may determine that the timing offset corresponding to CS4 is 10 samples. In this case, when the delay offset is applied in determining the detection region, the controller 320 may detect the timing offset by removing the delay offset from the interval between the CS and the peak sample. That is, if the delay offset is 20 samples, the controller 320 may determine that the timing offset corresponding to CS4 is zero. On the other hand, if the peak sample is located in the time period of the detection area, the controller 320 may determine that the timing offset is 0 even if the interval between the CS and the peak sample is not zero.

Next, the controller 320 adjusts timing according to the timing offset in step 421. That is, the controller 320 controls the terminal to adjust the timing according to the timing offset. Here, the procedure of the controller 320 to adjust the timing with each terminal may proceed as follows.

FIG. 12 is a flowchart for explaining a timing adjusting method of FIG. 11.

Referring to FIG. 12, the controller 320 determines whether the timing is delayed in step 511. That is, the controller 320 determines whether a peak sample is detected in the delay section of the detection area corresponding to the CS of the terminal. If it is determined that the timing is delayed, the controller 320 transmits a command to advance the timing to the terminal in step 513 and then returns to FIG. 11. In this case, the controller 320 may request the terminal to advance timing at an interval corresponding to the timing offset.

On the other hand, if it is determined in step 511 that the timing is not delayed, the controller 320 determines whether the timing is preceded in step 521. That is, the controller 320 determines whether the peak sample is detected in the preceding section of the detection area corresponding to the CS of the terminal. If it is determined that the timing has been preceded, the control unit 320 transmits a command to delay the timing to the terminal in step 523, and then returns to FIG. 11. In this case, the controller 320 may request the terminal to delay the timing at an interval corresponding to the timing offset.

On the other hand, if it is determined in step 521 that the timing is not preceded, the control unit 320 returns to FIG. That is, when a peak sample is detected in the CS of the terminal, the controller 320 maintains timing with the terminal. In this case, the controller 320 may selectively transmit a command for maintaining timing to the terminal. Here, the controller 320 may set the timing offset to 0 and transmit the timing offset to the terminal.

According to the present invention, the base station can variably determine a detection area for estimating the timing of the terminal. Therefore, even if the timing gap between the base station and the terminal increases, the base station can efficiently detect the timing of the terminal. Accordingly, the accuracy of estimating timing at the base station can be further improved.

It should be noted that the embodiments of the present invention disclosed in the present specification and drawings are only illustrative of the present invention in order to facilitate the understanding of the present invention and are not intended to limit the scope of the present invention. That is, it will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention can be implemented.

Claims (12)

In the timing adjustment method of a base station in a communication system,
Allocating CSs to the connected terminals,
Determining detection areas corresponding to the CSs according to the number of terminals and the interval of the CSs;
Detecting SRSs of the terminals in the detection regions;
And adjusting the timing with the terminal according to the interval between the CS and the SRS in each of the detection areas. The method of claim 1, wherein the determining process,
And detecting detection areas corresponding to the two CSs based on a center point between any two adjacent ones in the CSs. The method of claim 1, wherein the detection process,
And detecting a peak sample in each of the detection areas with the SRS. The method of claim 1, wherein the adjusting process,
In response to the timing delay, transmitting a command to advance the timing to the terminal,
And transmitting a command for delaying the timing to the terminal when the timing is preceded. The method of claim 1, wherein the adjusting process,
If the interval between the CS and the SRS is zero, maintaining a timing with the terminal. The method of claim 1, wherein the adjusting process,
And adjusting the timing according to a value obtained by removing a preset offset so as to be delayed from the CS in the interval between the CS and the SRS. In the timing adjustment device of a base station in a communication system,
A memory for storing corresponding CSs allocated to the connected terminals, respectively;
A timing detector for determining detection regions corresponding to the CSs according to the number of terminals and the interval of the CSs, and detecting SRSs of the terminals in the detection regions;
And a control unit for adjusting timing with the terminal according to the interval between the CS and the SRS in each of the detection regions. The method of claim 7, wherein the timing detector,
And determining detection areas corresponding to the two CSs based on a center point between any two adjacent ones in the CSs. The method of claim 7, wherein the timing detector,
And the peak sample is detected by the SRS in each of the detection areas. The method of claim 7, wherein
Under the control of the control unit, when the timing delay, the wireless communication unit for transmitting a command for preceding the timing to the terminal, and when the timing is prior to, transmitting a command for delaying the timing to the terminal further comprises; The timing adjustment device characterized by the above-mentioned. The method of claim 7, wherein the control unit,
And if the interval between the CS and the SRS is 0, maintaining the timing with the terminal. The method of claim 7, wherein the control unit,
And adjusting the timing according to a value obtained by removing a preset offset so as to be delayed from the CS in the interval between the CS and the SRS.

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