KR100766476B1 - System and Method for Position Detection in Orthogonal Frequency Division Multiplexing Mobile Repeater - Google Patents

Abstract

The present invention relates to an apparatus and method for detecting a location of a terminal using a preamble time offset of an OFDM mobile communication system. By setting different preamble offsets for each repeater device belonging to a base station, radio resources can be efficiently utilized. The location of the terminal can be easily identified.

Repeater, OFDM, Offset, Location Information, LBS

Description

System and method for location detection in orthogonal frequency division multiplexing mobile repeater {System and mtehod for location acquisition of terminal in OFDM mobile telecommunication system}

1 is a diagram illustrating a preamble related channel structure in an orthogonal frequency division multiple modulation system.

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

3 is a conceptual diagram illustrating an offset value setting of a preamble.

4 shows an example of preamble transmission with different offsets for each repeater.

5 is a graph illustrating preamble transmission on / off control.

6 is a graph illustrating a plurality of preamble on / off transmission states.

7 is a conceptual diagram of a base station system having a plurality of repeaters.

8 is a conceptual diagram of a hierarchical repeater system.

9 is a process flow diagram according to an embodiment of the present invention.

The present invention relates to an apparatus and method for enabling efficient use of limited radio resources and for determining the location of a user.

In general, Wibro (Wireless Broadband Internet), which uses Orthogonal Frequency Division Multiplexing (OFDM), always uses the first symbol of a Tx signal transmitted from a base station as a preamble. . Referring to FIG. 1, the preamble signal is divided into 114 kinds of PN codes, which are the total number of subcells to the base station around the second tier composed of 6 sectors, and is expressed as preamble_index. That is, 114 different orthogonal codes of preambles are used to distinguish base stations. Hereinafter, in the present invention, a signal used by the preamble for identifying a base station or a cell in the base station is called a preamble.

By the way, there are a number of shaded areas in the area covered by the base station, and a plurality of repeaters are used to cover such a range.

In the mobile communication system, there is an accurate method using a terminal built-in GPS supported by a base station signal and an approximate method using a location of a base station to determine a call waiting state or a location of a terminal in a call. However, if the terminal is located in the area of the repeater installed in the underground structure, the GPS signal is not visible, the base station signal is delayed by the repeater, and the position of the terminal is linked to the repeater rather than the position of the repeater. As a result, a problem of illusion occurs, and thus, the position of the terminal cannot be grasped approximately.

Accordingly, the technical problem to be solved by the present invention to solve the above problems is to determine the position of the repeater unit under which the repeater terminal is located in the orthogonal frequency division multiple mobile communication system (WiBro, WiMAX, etc.) To understand.

Another technical problem to be achieved by the present invention is to minimize the preamble signal generated by the repeater to be considered as noise.

Another technical problem to be achieved by the present invention is to locate the terminals located in a plurality of repeater regions by using a given limited preamble resource without significant change of the conventional system, and the preamble acts as a noise to the base station preamble signal. It is to minimize the work done.

1 is a diagram illustrating a preamble related channel structure in an orthogonal frequency division multiple modulation system, FIG. 2 is a schematic diagram of a communication system according to an embodiment of the present invention, and FIG. 3 is a diagram illustrating an offset value setting of a preamble. 4 is a diagram illustrating a preamble transmission with different offsets for each repeater, FIG. 5 is a graph showing preamble transmission on / off control, and FIG. 6 is a graph showing a plurality of preamble on / off transmission states. 7 is a conceptual diagram of a base station system having a plurality of repeaters, FIG. 8 is a conceptual diagram of a hierarchical repeater system, and FIG. 9 is a process flowchart according to an embodiment of the present invention.

As shown in FIG. 1, Wibro (Wireless Broadband Internet), which generally uses orthogonal frequency division multiplexing, always uses the first symbol of a Tx signal transmitted from a base station as a preamble. In the mobile Internet, the preamble signal is divided into 114 types of preamble signals, which are the total number of subcells to the base station around the second tier composed of 6 sectors, and is expressed as preamble_index. This preamble can be found in the TTAS.KO-06.0082 / R1 (2.3 GHz portable Internet standard, physical layer and media access control layer) standard published by the Korea Information and Communication Technology Association (TTA) on December 21, 2005. "8.4. Refer to 6.1.1 Preamble and "Preamble modulation series per segment and IDcell for the 1K FFT mode" on page 777 of the standard.

Handoff process

On the other hand, the idle state (Idle) or busy terminal 200 must periodically search for the preamble signal of the neighboring base station for the handoff to the neighboring base station. The base station 100 should periodically inform the terminal 200 of the neighbor base station information through the MOB_NBR-ADV message, which should include the preamble_index of the neighbor base station. The terminal 200 searching for the preamble signal of the neighbor base station transmits the MOB_SCN_REP message to the base station 100 when the condition defined in the MOB_SCN_RSP message is met. Important information included in the MOB_SCN_REP includes the carrier-to-interference-and-noise ratio (CINR) and RSSI of the current base station (Anchor or serving BS: 100), the preamble_index of the searched neighbor base station (target BS) preamble signal, and the current base station (100). ) And the relative delay value, which is a time difference from the signal. Upon receiving the MOB_SCN_REP signal, the base station 100 determines the handoff condition and proceeds with the handoff process.

Of the present invention Example  Parameter definition

In order to implement the system according to the present invention, the following parameters are defined.

parameter Justice pre_index_R Designate one of the 114 indexes for the repeater pre_index_R_delay Time delay value for Pre_index_R signal Pre_index_R_att Relative level value of Pre_index_R signal compared to repeater DL output level Pre_index_R_period Gate on / off cycle of Pre_index_R signal Pre_index_R_duty Gating on ratio of Pre_index_R signal Pre_index_R_gate_no Gate on order

First, one preamble (pre_index_R) of the 114 preamble indexes is allocated to the repeater 10 dedicated to LBS (Location Based Service) so that it is not used by all base stations. That is, the base station 100 uses 113 preamble indexes. Inside the repeater 10 adds the following functions.

@ A function of generating a pre_index-R preamble signal synchronized with the Tx / Rx switching signal extracted from the repeater 10

A function of controlling the @ pre_index_R signal with a time delay value (pre_index_R_delay) relative to the downlink DL (base station => relay direction) signal (see FIG. 3).

@ Pre_index_R A function for controlling the size of the preamble signal to a level relative to the size of the repeater downlink (base station => relay direction) signal (pre_index_R_att) (see FIG. 5).

Function to gate on / off output of @ pre_index_R signal by pre_index_R_duty in pre_index_R_period period (refer to FIGS. 5 and 6)

Remote control of @ pre_index_R_delay and pre_index_R_att values.

@ Repeater DL signal mixed with pre_index_R signal

How to distinguish multiple repeaters using one preamble index

First, a method for distinguishing a plurality of repeaters 10 by using one preamble index will be described. Considering that up to 6 to 7 large repeaters 10 are linked to one base station 100, 6 to 7 preamble indexes should be dedicated for the repeater 10 in order to locate the repeaters. However, dedicating such a large number of indexes to repeaters in 114 indexes creates a lot of limitations in the design of the wireless network. In order not to generate such a constraint, even if a plurality of repeaters 10 are linked to one base station 10, only one preamble index is allocated for the repeater.

The interworking repeaters 10 are distinguished by offsetting the time reference of the index_R preamble signal generated by the LBS repeater 10 at a frame boundary (see FIGS. 3 to 6). The interworking repeaters are uniquely assigned pre_index_R_delay. The preamble is offset from the frame as many times as it is sent. The terminal recognizes the Pre_index_R signal and transmits the delay value measured when transmitting the MOB_SCN_REP message to the base station 100 in the message field (time difference value with the index_B signal) to the base station 100.

Upon receiving the MOB_SCN_REP message, the base station 100 reads the delay value of the message field to determine which repeater 10 exists under the terminal 200 that has sent the message. To this end, the base station 100 stores information of each preamble index and offset.

MOB_SCN_REP is a parameter transmitted from the terminal 200 to the base station 100 and reports the scanning result value in the terminal 100. This is described on page 234 of the TTA Portable Internet Standard TTAS.KO-06.0082 / R1. Among the messages of MOB_SCN_REP, "Neighbor_BS_Index" is able to transmit "BS index corresponds to position of BS in MOB_NBR-ADV message" with 8 bits, and it is defined to transmit 8 bits of information through "Relative delay". This is described in the table MOB_SCN-REP message format. The information of the neighboring base station can be known through the former parameter transmitted from the terminal 200 to the base station 100, and the time delay information between the normal preamble signal and the preamble signal given the offset can be obtained through the latter parameter. Can be.

Therefore, even if all repeaters use the same preamble, if the preamble offset is allocated differently in the repeater unit, the position information of the terminals 200 belonging to different repeaters 10 may be obtained through the MOB_SCN_REP message transmitted from the terminal. .

Repeater Preamble  Minimization of interference by signal

On the other hand, the preamble signal output from the repeater 10 inevitably lowers the CINR of the signal output from the base station 100. If the CINR value is deteriorated, a lower efficiency modulation and channel coding technique is applied to improve communication reliability in a communication system using AMC (Adaptive Modulation & Coding), resulting in a decrease in cell total throughput. . In order to prevent such a problem, the strength of the index_R preamble signal generated by the repeater 10 should be at a sufficiently low level (pre_index_R_att) compared to the present signal (index_B preamble: a signal transmitted from the base station) (see FIG. 5). If this value is too low, the effect of the CINR is minimized, but the terminal 200 has difficulty in detecting the presence of the repeater 10. If the value is too high, the CINR value of the present signal is seriously deteriorated. Therefore, the optimal value is derived through pre-index_R_att optimization.

However, due to the characteristics of the location information service, the terminal 200 under the repeater 10 does not need to detect the repeater 10 preamble signal within msec in real time. Accordingly, the repeater 10 preamble signal is gated on / off periodically without the need for continuous transmission to minimize the CINR degradation of the present signal (see FIGS. 5 and 6).

The gate period is defined as the pre_index_R_period value transmitted from the base station, and the gate on ratio is defined as pre_index_R_duty. The optimal value of this parameter is derived through optimization.

If the gate on time points of the multiple repeaters 10 linked to one base station 100 coincide, CINR degradation of all the repeater 10 signals occurs at the same time, thereby lowering the cell total throughput. In order to prevent this, the plurality of repeaters 10 sequentially advance the preamble signal Gate on time point as shown in FIG.

In other words, the portable Internet communication system using the orthogonal frequency division multiplexing scheme distinguishes the fast synchronization from the base station 100 by using one or two symbols in front of a downlink frame (one transmission / reception period: 5 msec in the case of WiBro) as a preamble. Used for the purpose of. Thus, each base station 100 uses different preamble signals or reuses the same preamble signal at a sufficiently long base station 100. Since the base station 100 is distinguished by the preamble signal, the terminal 200 which is in a call or in the call waiting state detects the quality of the neighboring base station 100 preamble signal to determine the movement to the neighbor base station 100. When the level is reached, handoff is performed to the neighboring base station 100 in consultation with the base station 100.

Hereinafter, the preamble operating method according to the present invention will be described in detail. OEC (Optic to Electronic Converter) 11 converts an optical signal into an electrical signal when the base station and an optical cable are connected. In the present invention, the preamble signal generator 12 is built into the repeater 10 to determine the position of the terminal 200 belonging to the repeater 10 separately from the base station 100. The output of the preamble signal generator 12 according to the pre_index_R information transmitted from the base station is input to the offset controller 13, and the offset controller 13 adjusts the offset according to the pre_index_R_delay value transmitted from the base station 100 to preamble signal. Outputs

This may be implemented by a time delay circuit for controlling the start of the code or sequence used for the preamble signal. The output signal of the offset regulator 13 is input to the gate on / off regulator 14. The control unit 19 of the repeater 10 detects the gate on / off control signals " Pre_index_R_duty ", " Pre_index_R_period ", and " Pre_index_R_gate_no " 14) to output a preamble signal.

The output signal of the gate on / off controller 14 is input to the output controller 15 for adjusting the relative magnitude of the output signal, and is scaled and output by "Pre_index_R_att".

The amplifier 15 amplifies the general signal received from the base station and the preamble signal generated by the repeater 10. The control unit 19 receives various control signals related to the preamble received from the base station, and thus the preamble generator 12, the offset controller 13, the gate on / off controller 14, the output controller 15, and the amplifier 15. Perform an operation to control the. In addition, means for processing a signal received from the terminal is not shown.

The repeater 10 synchronizes with the transmission / reception switching signal extracted from the downlink of the base station 100, and the generated preamble signal is mixed with the signal of the base station 100 and output through the amplifier 15.

When the plurality of repeaters 10 linked to one base station 100 cannot use different preamble signals due to the limitation of the number of preambles that can be used, the same preamble signal is used for all the repeaters 10 and each repeater ( In order to distinguish 10), the offset controller 13, which is a preamble signal time delay device, is configured so that the start point of each code or sequence used in the preamble signal is different from the start point of the frame (transmission and reception period). By such a configuration, the terminal 200 determines a time difference (set differently for each repeater) between the orthogonal frequency division multiple base station 100 signal passing through the repeater 10 and the repeater 10 preamble signal transmitted mixed with the signal. By measuring and reporting to the base station 100, it is possible to determine which repeater 10 is located below the terminal 200. This reporting function is performed by the existing base station 100 handoff function.

Meanwhile, the downlink base station 100 passing through the repeater 10 by the preamble signal of the repeater 10 using the same frequency in generating the preamble signal from the repeater 10 and mixing and transmitting the base station 100 signals. The degradation of the signal inevitably occurs. In order to minimize the performance degradation, the base station 100 signal passing through the repeater 10 by the repeater 10 preamble is controlled so that the size of the repeater 10 preamble is relatively proportional to the size of the base station 10 signal. Minimize and equalize performance degradation (see FIG. 5). 6, the signal generated by the base station 100 and transmitted through the repeater 10 has the same size as Pre_index_B_signal, and the preamble signal generated by the repeater 10 has the same size as Pre_index_R_signal. Output In addition, the preamble is not always output continuously, but does not act as a noise on other signals during the gated off time. Accordingly, as shown in FIG. 6, the gate is turned on / off at a predetermined time interval and output, but the signal may be output at a smaller ratio than the base station downlink signal passing through the repeater. Also, the repeaters 10 interlocked with one base station 100 are controlled so that the time when the repeater preamble signal is gated on does not overlap each other (see FIG. 6). As shown in FIG. 6, the gate-on time of the preamble signal output for each repeater 10 does not overlap each other, thereby minimizing interference with the base station downlink signal.

In the case of a subway repeater 10 system or a large building serving several subway stations by one base station 100 or a repeater 10, the repeater 10 has a form of a distributed repeater 10 having a hierarchical structure ( 7 and 8). In this case, the location of the preamble generator may be located in the intermediate or final stage repeater 10 in order to classify the location classification or subway history in the building, thereby increasing the accuracy of the location tracking.

When servicing a large number of subway stations (usually 2 to 4 stations) by one MHU (Main Hub Unit: 90), it becomes difficult to locate the subway station. In such a distributed structure of a subway repeater, an index_R preamble signal is generated by a RHU (Remote Hub Unit: 91, 92, 93) installed in a history unit as shown in FIG. To distinguish each RHU, it can be solved by setting different pre_index_R_delay value for each RHU. RU (Remote Unit: 94, 95) only performs the function of amplifying and receiving the received signal according to the preamble offset transmitted from the RHU (91, 92, 93). The device 96 connected to the rear end of the RHs 94 and 95 is an antenna unit, which is a substantial wireless output device.

Of the present invention Example  According to

Referring to FIG. 9, in operation 900, the base station 100 or the base station higher location information management system stores location information of the repeaters 10 allocated for each preamble index and offset.

In step 910, the base station 100 transmits index and offset information, gate on / off information, and preamble output strength information for generating a preamble to each repeater 10 using the parameters shown in the above table.

In step 920, the terminal 200 obtains the CINR from the received signal by acquiring the repeater preamble information, and compares the preamble signal transmitted from the base station to the preamble signal transmitted from the repeater 10 to which it belongs. The relative time delay value information is acquired and reported to the base station 100 through the MOB_SCN_REP (step 930). As an example in the present invention, CINR, general signal to noise ratio (SNB), signal to interference ratio (SIB), and the like may also be used.

In step 940, the base station 100 or the upper position information management system acquires the position information of the repeater 10 in which each terminal is located through the received MOB_SCN_REP information to determine the position of the repeater to which the terminal belongs. In step 950, the base station 100 compares the signal strength of the preamble transmitted by each repeater 10 with the signal strength determined as a reference value, and details the gay on / off information and the intensity information for adjusting the preamble output. Loop back to step 910 to transmit using a table parameter.

Through the above-described procedure, it is possible to determine the position of the repeater to which the base station 100 or the upper position information management system terminal belongs.

Accordingly, in the present invention, an offset of an orthogonal frequency division multiple preamble is differently allocated to each repeater, and the gate of the transmission of the repeater preamble is gated on / off, so that a terminal of a mobile communication system (WiBro, WiMAX, etc.) using the preamble is a repeater. If located below, it can determine the position of the repeater unit under which repeater it is located, minimize the preamble signal to be considered as noise, and utilize the given preamble resources without significant fluctuations in the conventional system. The location of the located terminal can be determined, and the preamble can minimize the noise.

Claims (9)

In the Orthogonal Frequency Division Multiple Mobile Communication System, One or more relays which relay and output a signal transmitted from the base station, and output a preamble signal to have different offsets according to the allocated information; And, The server stores the preamble offset information allocated to each of the repeaters and determines the location of each terminal based on the information reported from the terminals belonging to the repeater. System for positioning in the orthogonal frequency division multiple mobile communication repeater characterized in that it comprises. The method according to claim 1, The repeater, And a gate on / off controller for gate-on / off output of a preamble signal according to the allocated information. The method according to claim 1 or 2, The repeater, A preamble generator for generating a corresponding preamble according to the allocated information; An offset controller for outputting a preamble by delaying a signal output from the preamble generator for a predetermined time; And, And an output regulator for adjusting the output strength of the preamble. In the method for the identification of orthogonal frequency division multiple mobile communication system, A first step of transmitting information for generating a preamble for each repeater; Detecting a preamble offset value of a repeater to which the terminal belongs from a message transmitted from the terminal; And, Step 3 of detecting and storing the position of the repeater to which the terminal belongs through the detected offset value Method for location determination in orthogonal frequency division multiplexing mobile repeater characterized in that it comprises a. The method according to claim 4, Detection of the offset value, And detecting offset value of the repeater to which the terminal belongs from the scanning result report message. The method according to claim 4 or 5, Receives a preamble-related information for obtaining the relative size information of the signal transmitted from the terminal and the information of the repeater for the corresponding area belonging to the terminal, And generating and transmitting control information for adjusting preamble output according to the relative magnitude information of the received signal. The method according to claim 6, The size of the preamble signal is automatically adjusted in proportion to the size of the base station downlink signal passing through the repeater method for position detection in orthogonal frequency division multiplexing mobile repeater. The method according to claim 6, Receives information for generating a preamble for each repeater and gate on / off information, Generating a preamble signal according to the received signal; Outputting the generated preamble signal on / off according to the gate on / off information Method for positioning in the orthogonal frequency division multiplexing mobile repeater characterized in that it further comprises. The method according to claim 7, And a gate-on time point of the preamble signal is different for each repeater.

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