KR100662930B1 - Frame structure for hand-off in tdma tdd type mobile system, and method for transmitting data on scanning bts by using it - Google Patents

Abstract

The present invention relates to a frame structure of a TDMA TDD mobile communication system and a data transmission method for scanning a base station using the same. Particularly, the method of the present invention provides a serving service in a mobile station when the base station signal quality transmitted from the base station falls below a predetermined reference. Requesting a scan of a neighbor base station for handoff to the base station, allowing the serving base station to scan the neighbor base station using a downlink TDM burst period of the TDD frame, and switching from the mobile station to the frequency of the neighbor base station; Performing a scan for the handoff, and if there is a downlink TDMA burst from the serving base station, and after synchronizing the mobile station with the serving base station by a preamble in the downlink TDMA burst period, the serving base station through the downlink burst in the downlink TDMA burst period; Transmitting data from to the mobile station; And performing a handoff procedure to the neighboring base station when a signal quality higher than a predetermined reference is detected from the neighboring base station in the same station. Therefore, the present invention can directly perform data transmission from the serving base station to the mobile station upon scanning of the neighbor base station for handoff by adding an additional TDMA burst to the downlink TDM burst.

TDD frame, downlink TDMA burst, data transmission

Description

FRAME STRUCTURE FOR HAND-OFF IN TDMA TDD TYPE MOBILE SYSTEM, AND METHOD FOR TRANSMITTING DATA ON SCANNING BTS BY USING IT}

1A and 1B are schematic diagrams illustrating a structure of a synchronous and asynchronous frame between base stations in a mobile communication system of a general TDMA TDD;

2 illustrates a frame structure of a TDMA TDD mobile communication system according to the present invention;

3 illustrates a preamble, burst information and data in a downlink TDMA burst period of a frame according to the present invention;

4 is a structural diagram between a mobile station and a base station for explaining a data transmission method when scanning a base station using a frame of a mobile communication system of TDMA TDD according to the present invention;

5 is a flowchart sequentially illustrating an example of a method for transmitting data during base station scan using a frame of a TDMA TDD mobile communication system according to the present invention;

<Description of the code | symbol about the principal part of drawing>

10: cell 20: serving base station

20a, 20b, 20c: neighboring base station 30: mobile station

117: downlink TDM burst 119: downlink TDMA burst

119_1, 119_5,... 119_n-1: Preamble

119_3: first down burst 119_7: second down burst

119_n: nth down burst a: burst information

b: data information

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile communication system of TDMA TDD, and more particularly, to a frame structure of a mobile communication system of TDMA TDD capable of performing handoff without loss of transmission data or transmission delay during scanning of neighboring base stations, and data during scanning of base station It relates to a transmission method.

In the TDMA TDD type mobile communication system, one frequency band is divided in time and transmitted in the uplink and the downlink, and the uplink and the downlink multiplex or multiple access time slots in basic units, respectively. The TDMA TDD type mobile communication system can dynamically allocate time intervals of uplink and downlink according to the amount of uplink and downlink traffic, which is advantageous for asymmetric data transmission such as Internet service. Examples of a system employing the TDMA TDD scheme include WLAN or WMAN such as HIPERLAN / 2, HIPERMAN, and IEEE802.16.

However, in the TDMA TDD type mobile communication system, since frequencies for uplink and downlink frame transmission are the same, if adjacent cells using the same frequency exist, performance is greatly degraded due to mutual interference of the cells. Therefore, it is difficult to set the frequency reuse coefficient to 1, and as shown in FIG. 4, the frequency reuse coefficient should be 3 or more when a hexagonal omnidirectional cell structure is assumed to minimize the interference between the cells 10. That is, one cell cluster is composed of at least three cells. If adjacent cells use different frequencies, the uplink and downlink intervals may be asymmetric for each cell. However, since the transmission signal strengths of the base station and the mobile station are different in uplink and downlink, out-of-band firing ( Inter-cell interference using adjacent bands may occur due to unwanted emission, such as out-of band emission or spurious emission.

Accordingly, in order to apply the TDD scheme to a mobile communication system in a multi-cell environment, a synchronization system between base stations is implemented as shown in FIG. 1A in order to minimize performance degradation and system capacity degradation due to interference between cells. This inter-base station synchronization system includes downlink and uplink subframe rates that are asymmetric with each other in up / down links for frequencies f1 and f2 of all cells (eg, Cell # 1 and Cell # 2) and start of a frame. And end time coincide. In this case, the TDD frame is divided into a downlink and an uplink subframe. The downlink subframe includes a preamble, a base station information transmission section, a frame information transmission section, and a downlink TDM burst. The uplink subframe consists of a contention period and an uplink TDMA burst.

Alternatively, it can also be implemented as an asynchronous system between base stations, as shown in Figure 1b, which includes the ratio of the down and up frame subframes asymmetric with each other in the up / down link for each cell and the start and end times of the frame coincide I never do that. When a sufficient guard band with adjacent frequency bands (for example, f1 and f2) is secured, it may be configured as a mobile communication network of an asynchronous system. In this case, the structure of each frame in FIG. 1B is the same as the frame structure described in FIG. 1A, and Td denotes a synchronization error between base stations and T_du denotes a difference in uplink / downlink transmission allocation between base stations.

In the TDMA TDD mobile communication system having such synchronous and asynchronous characteristics, the serving base station switches from a serving base station to a frequency used by a neighboring base station for handoff of an inter-cell mobile station, and transmits information of a neighboring base station such as a broadcast channel in HIPERLAN / 2. The procedure for acquiring the information to obtain the information and handing off to the target base station should be performed.

In this scanning process, the conventional TDMA TDD mobile communication system pauses transmission of data to be transmitted to the mobile station while scanning neighboring base stations for handoff, and stores the data in the serving base station and transmits the data while not scanning. This causes a delay or loss of data transmission. As a result, there is a problem in that the scanning of the base station and the reception of the frame from the serving base station cannot be simultaneously performed. Therefore, in the conventional system, there is a problem in that a data service which is relatively sensitive to transmission delay such as voice or streaming is cut off during the scan of the base station for handoff.

An object of the present invention is to perform the data transmission from the serving base station to the mobile station during the scan of the neighbor base station for handoff by adding an additional TDMA burst to the down TDM burst of the downlink subframe to solve the problems of the prior art as described above The present invention provides a frame structure of a mobile communication system of TDMA TDD.

Another object of the present invention is to provide a method for transmitting data during base station scan using a frame structure of a TDMA TDD mobile communication system capable of performing data transmission from a serving base station to a mobile station during scanning of an adjacent base station for handoff. .

In order to achieve the above object, the present invention provides a TDD type frame having a downlink subframe transmitted during downlink and an uplink subframe transmitted during uplink between a mobile station and a base station in a mobile communication system. And a downlink TDMA burst duration consisting of a preamble for acquiring synchronization for the base station after the downlink TDM burst and a downlink burst for transmitting data from the base station to the mobile station.

In order to achieve the above object, the present invention provides a frame in a downlink subframe of a frame in a TDD type frame having a downlink subframe transmitted during downlink and an uplink subframe transmitted during uplink in a mobile communication system. 10. A method of data transmission during base station scan using a frame structure comprising a preamble for acquiring synchronization for a base station after a downlink TDM burst and a downlink TDMA burst period consisting of a downlink burst for transmitting data from the base station to a mobile station, the base station comprising: If the transmitted base station signal quality falls below a predetermined criterion, requesting a scan of an adjacent base station for handoff from the mobile station to the serving base station; and using the downlink TDM burst interval of the TDD frame at the serving base station to approach the mobile station; Allow the base station to scan Performing a scan for handoff by switching to a frequency of an adjacent base station in the mobile station, and acquiring synchronization between the mobile station and the serving base station by a preamble in a downlink TDMA burst period when there is a downlink TDMA burst from the serving base station. Later, transmitting data from the serving base station to the mobile station through the down burst of the downlink TDMA burst period, and performing a handoff procedure to the neighboring base station if a signal quality higher than a predetermined reference is detected from the neighboring base station in the mobile station. It includes.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

2 illustrates a frame structure of a TDMA TDD mobile communication system according to the present invention.

2, a TDMA TDD mobile communication system according to the present invention synchronizes with a mobile station in a downlink TDMA burst period added after a downlink TDM burst in a downlink frame during scanning of an adjacent base station for handoff. Send downlink data accordingly.

To this end, the TDD frame 100 structure of the present invention is divided into downlink and uplink subframes 110 and 120, and the downlink subframe 110 is sequentially a preamble 111 and a base station information transmission section 113. , A frame information transmission section 115, a downlink TDM burst 117, and a downlink TDMA burst 119. The uplink subframe 120 includes a contention section 121 and an uplink TDMA burst 123.

Here, the first preamble 111 is a section for synchronizing with the base station to restore the base station / frame information (information such as broadcasting) and the downlink data bus. The base station information transmission section 113 is a section for transmitting information such as a base station ID, a frame number, and a transmission mode / length of the frame information transmission section. The frame information transmission section 115 is a section for transmitting allocation information of the burst / mobile station on the downlink / uplink. In addition, the downlink TDM burst section 117 is the beginning and end of the burst allocated to the mobile station using the base station information transmission section 113 and the frame information transmission section 115 information in synchronization with the base station from the first preamble 111 Is a section to receive in the proper transmission mode.

The downlink TDMA burst section 119 according to the present invention is divided into at least one preamble and a downlink burst which is a data section (payload). For example, the first preamble 119_1, the first down burst 119_3, the second preamble 119_5, the second down burst 119_7,. , N-th preamble 119_n-1, and n-th down burst 119_n. Here, the preambles 119_1, 119_5, and 119_n-1 may be different from the initial preamble located at the start of the frame as a section for obtaining synchronization between the mobile station and the base station during the scan.

Each downlink burst 119_3, 119_7,..., 119_n in the downlink TDMA burst 119 section includes burst information (a) and data section (b), where the burst information (a) is assigned by a mobile station approved by the base station. The data section b includes all data values transmitted to the base station as control information and service data.

Accordingly, in the downlink TDMA burst section 119 of the present invention, the start information of the downlink TDMA burst section previously known from the base station information and the frame information transmission sections 113 and 115 is not synchronized with the base station by the first preamble 111. After switching to the reception mode using the first preamble 119_1 and synchronizing with the base station, the allocation information of the mobile station is found from the burst information (a) included in the first down burst 119_3 and assigned. The data information b is transmitted to the mobile station.

Here, the contention period 121 in the uplink subframe 120, which is not described, is a random access period set for initial access, request for uplink data transmission, etc. of the mobile station, and the uplink TDMA burst 123 period is an initial preamble 111. The first and the end of the burst allocated to the mobile station are transmitted in the appropriate transmission mode using the contention section 121 information in synchronization with the base station.

3 is a diagram illustrating preambles, burst information, and data in a downlink TDMA burst period of a frame according to the present invention.

Referring to FIG. 3, the downlink TDMA burst section of the frame according to the present invention transmits at a higher transmit power than the downlink TDM burst section 117 having the same radio channel environment. Preferably, the transmission power of the downlink TDMA burst 119 section is boosted and transmitted by a predetermined value ΔP relative to the downlink TDM burst 117 section, which is another section, thereby increasing the reception probability of the mobile station.

4 is a structural diagram between a mobile station and a base station for explaining a data transmission method when scanning a base station using a frame of a TDMA TDD mobile communication system according to the present invention.

Referring to FIG. 4, in a mobile communication system divided into a plurality of cells (Cell # 1, Cell # 2, Cell # 3, Cell # 4), a base station adjacent to a serving base station 20 of a cell where a mobile station 30 is located. Transmission of data to be transmitted from the serving base station 20 to the mobile station 30 when the mobile station 30 scans information of neighboring base stations 20a, 20b, and 20c for handoff to 20a, 20b, and 20c. This operation is performed in the downlink TDMA burst period of the frame without stopping.

5 is a flowchart sequentially illustrating an example of a method for transmitting data during base station scan using a frame of a TDMA TDD mobile communication system according to the present invention. 2 to 5, a method of transmitting data during base station scan using a frame of a TDMA TDD mobile communication system according to the present invention proceeds as follows.

The mobile station 30 periodically receives the neighbor base station information from the serving base station 20 and measures signal quality such as signal strength, signal-to-noise ratio, and frame error rate according to the transmitted base station information, and the measured signal quality is equal to or less than a predetermined standard. Judge to fall. (S10-S12)

As a result of determination, when the measured signal quality falls below a predetermined criterion, the mobile station 30 requests the uplink bandwidth to the serving base station 20 using the contention period of the TDD frame, and the serving base station 20 transmits frame information of the TDD frame. The uplink bandwidth is allocated to the mobile station 30 using the interval (S14 to S16).

The mobile station 30 allocated the uplink bandwidth requests the serving base station 20 to scan the neighbor base stations 20a, 20b, and 20c for handoff. (S18) Here, the scan request is an uplink TDMA burst period of a TDD frame. In this case, the serving base station 20 may inform the information of the neighbor base stations 20a, 20b, and 20c in advance through the base station information transmission section of the TDD frame.

The serving base station 20 allows the mobile station 30 to scan the adjacent base stations 20a, 20b, and 20c using the downlink TDM burst period of the TDD frame.

The mobile station 30 receiving the scan from the serving base station 20 uses the neighbor base station information stored in advance to switch to the frequency of the neighbor base stations 20a, 20b, and 20c for handoff or to switch from an arbitrary frequency to perform the scan. (S22 to S24) In this case, frequency switching is performed during the downlink transmission period of the TDD frame of the serving base station 20, and scanning of the neighbor base stations 20a, 20b, and 20c is performed by the neighbor base stations 20a, 20b, and 20c. Proceeds during the downlink transmission interval of the TDD frame.

The mobile station 30 that is allowed to scan does not scan the neighboring base station in the downlink TDMA burst period, and checks whether there is a downlink TDMA burst delivered to itself. That is, after acquiring synchronization with the serving base station 20 in the preamble of the downlink TDMA burst period using the downlink TDMA burst period of the TDD frame without having to restore the base station information transmission period or the frame information transmission period of the TDD frame, Data such as arbitrary voice or wireless data is received from the serving base station 20 through the burst and data interval of the downlink TDMA burst interval.

More specifically, before checking whether there is a downlink TDMA burst, the serving base station 20 must send the maximum length of the downlink TDMA burst assignment to the mobile station 30 in the base station information transmission interval of the TDD frame in advance. Accordingly, the mobile station 30 finds a short preamble of the downlink TDMA burst from the point corresponding to the maximum value of the downlink TDMA burst section length, acquires synchronization thereto, and receives a control or data signal from the serving base station 20 through the downlink TDMA burst section. Receive.

In this way, since the mobile station 30 can receive data from the serving base station 20 even when the neighboring base stations 20a, 20b, and 20c are scanned, it is possible to support a radio data service sensitive to transmission delay.

When the mobile station 30 generates data to be transmitted in response to the received data, the mobile station 30 requests an uplink bandwidth to the serving base station 20 using the contention period of the TDD frame, and the serving base station 20 scans the mobile station 30 being scanned. Since the uplink TDMA burst is not known, the uplink bandwidth is allocated to the mobile station 30 using the downlink TDMA burst interval of the TDD frame. S30)

The mobile station 30 allocated with the uplink bandwidth transmits data such as arbitrary voice or wireless data from the mobile station 30 to the serving base station 20 using the uplink TDMA burst period of the TDD frame (S32).

In this procedure, the neighboring base station 20a, which transmits data between the serving base station 20 and the mobile station 30 and scans the neighboring base stations 20a, 20b, and 20c, guarantees a signal quality higher than a predetermined reference. If 20b, 20c is found, the handoff procedure is performed using the neighboring base stations 20a, 20b, and 20c as target base stations (S34 to S36).

On the other hand, the present invention is not limited to the above-described embodiment, various modifications are possible by those skilled in the art within the spirit and scope of the present invention described in the claims to be described later. For example, in the foregoing description of the method of the present invention, the serving base station 20 transmits data from the serving base station 20 to the mobile station 30 when the neighboring base stations 20a, 20b, and 20c are scanned. Although all of the uplink data transmission to the base station 20 has been described, data may be transmitted only in one of these directions between the serving base station and the mobile station when the neighboring base station is scanned for handoff.

As described above, since the present invention can perform data transmission from the serving base station to the mobile station during the scan of the neighbor base station for handoff by adding an additional TDMA burst to the downlink TDM burst, Problems such as data transmission delay can be prevented.

Claims (12)

In a TDD frame having a downlink subframe transmitted during uplink and uplink subframe transmitted during uplink between a mobile station and a base station in a mobile communication system, A downlink TDMA burst duration consisting of a preamble for acquiring synchronization for the base station after a downlink TDM burst in the downlink subframe of the frame, and a downlink burst for transmitting data from the base station to the mobile station; Frame structure of the mobile communication system of the TDMA TDD comprising a. The method of claim 1, The frame structure of the TDMA TDD mobile communication system, characterized in that at least one of the preamble and the down burst in the downlink TDMA burst period. The method according to claim 1 or 2, The downlink burst frame structure of the TDMA TDD mobile communication system, characterized in that it comprises a burst information and a data interval. The method of claim 3, wherein The burst information includes allocation information of a mobile station approved by the base station, and the data section includes control information and data transmitted to the base station. The method according to claim 1 or 2, The power of the downlink TDMA burst period is boosted by a predetermined value compared to the downlink TDM burst period frame structure of the TDMA TDD mobile communication system. In a TDD-type frame having a downlink subframe transmitted during downlink and an uplink subframe transmitted during uplink between a mobile station and a base station in a mobile communication system, synchronization is performed to the base station after a downlink TDM burst in a downlink subframe of the frame. In the base station scan data transmission method using a frame structure comprising a preamble for acquiring a downlink and a downlink TDMA burst interval consisting of a downlink burst for transmitting data from the base station to the mobile station, Requesting a scan of an adjacent base station for handoff from the mobile station to the serving base station if the base station signal quality transmitted from the base station falls below a preset criterion; Allowing the serving base station to scan the neighboring base station to the mobile station using a downlink TDM burst period of the TDD frame; Performing a scan for handoff by switching to the frequency of the adjacent base station in the mobile station; If there is the downlink TDMA burst from the serving base station, after acquiring synchronization of the mobile station and the serving base station by a preamble in the downlink TDMA burst period, the serving base station from the serving base station to the mobile station through a downlink burst of the downlink TDMA burst period; Transmitting the data; Performing, by the mobile station, a handoff procedure to a neighboring base station when a signal quality higher than a predetermined reference is detected from the neighboring base station; A base station scan data transmission method using a frame structure of a TDMA TDD mobile communication system comprising a. The method of claim 6, The base station using the frame structure of the TDMA TDD mobile communication system, characterized in that at least one preamble and the down burst in the downlink TDMA burst period is provided to perform at least one data transmission from the serving base station to the mobile station. How to send data when scanning. The method according to claim 6 or 7, The downlink burst includes a burst information having allocation information of a mobile station approved by the base station, and a data section having the control information and data transmitted to the base station. Data transmission method during the base station scan using the. The method according to claim 6 or 7, In the step of transmitting the data, the base station scan data using the frame structure of the TDMA TDD mobile communication system, characterized in that for boosting the power of the downlink TDMA burst period by a predetermined value compared to the downlink TDM burst period Transmission method. The method of claim 6, The method, Prior to the step of requesting a scan of the neighboring base station, the mobile station requests an uplink bandwidth from the mobile station to the serving base station through a contention period of the TDD frame, and is upward from the serving base station to the mobile station through a frame information transmission period of the TDD frame. A method of transmitting data during a base station scan using a frame structure of a TDMA TDD mobile communication system, the method further comprising: allocating a bandwidth. The method according to claim 6 or 7, The method, After transmitting the data, transmitting data from the mobile station to the serving base station using an uplink TDMA burst period of the TDD frame when data to be transmitted from the mobile station to the serving base station is generated. A base station scanning data transmission method using a frame structure of a mobile communication system of TDMA TDD, characterized in that. The method of claim 11, The method, Prior to the step of transmitting data to the serving base station to the mobile station, the mobile station requests an uplink bandwidth from the mobile station to the serving base station through a contention period of the TDD frame, and upstream from the serving base station to the mobile station through the downlink TDMA burst period. A method of transmitting data during a base station scan using a frame structure of a TDMA TDD mobile communication system, the method further comprising: allocating a bandwidth.

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