KR101291465B1 - Method and system for handover in digital broadcasting system - Google Patents

Abstract

The present invention provides a handover that can continuously provide a service provided to the MS when a mobile station (MS: Mobile Station, hereinafter referred to as 'MS') joined to a digital broadcasting system moves between service areas. It relates to a method and a system. A method for handover in a digital broadcasting system comprising a receiver according to the present invention and a transmitter for transmitting a broadcast frame for providing a broadcast service to the receiver, when the receiver detects that the handover should be performed, the broadcast is performed. Searching for a frame providing the same broadcast service as the at least one currently provided broadcast service in a frame list included in the frame; and a frame for providing the same broadcast service as the at least one currently provided broadcast service is not found. If it is determined that the handover is impossible, and a frame providing the same broadcast service as the at least one currently provided broadcast service is searched for, the same broadcast service as the searched at least one currently provided broadcast service is searched for. The priority of the frames Determining one frame based on the region identifier information, selecting one frame among the frames providing the same broadcast service as the searched at least one currently provided broadcast service according to the determined priority, and then providing the selected frame And handing over to the transmitter.

Digital Broadcast Systems, Broadcast Frames, Handovers, Transmitters, Receivers

Description

Method and system for handover in digital broadcasting system {METHOD AND SYSTEM FOR HANDOVER IN DIGITAL BROADCASTING SYSTEM}

1 schematically illustrates the structure of a DAB system.

2 is a view schematically showing the structure of a DAB frame in a DAB system according to an embodiment of the present invention.

3A and 3B schematically illustrate an SI structure of a DAB frame in a DAB system according to an embodiment of the present invention.

4 is a diagram schematically illustrating multiplexing of a broadcast service in a DAB system according to an embodiment of the present invention.

5 is a diagram schematically illustrating a structure of a receiver for receiving a DAB frame in a DAB system according to an embodiment of the present invention.

6 is a diagram illustrating an operation of the receiver in a DAB system according to an embodiment of the present invention.

The present invention relates to a digital broadcasting system. In particular, when a mobile station (MS), which is subscribed to a digital broadcasting system, moves between broadcasting service areas, the broadcasting service provided by the MS is changed. It relates to a handover method and system that can be continuously provided without interruption.

Today, with the development of the telecommunications industry, the services provided by wireless communication systems are evolving into communication systems that transmit not only voice services but also large amounts of data such as packet data and circuit data. As a technology capable of receiving a digital broadcasting system has been proposed. The digital broadcasting system may be divided into systems such as digital audio broadcasting, digital video defense, and digital multimedia broadcasting. In particular, digital audio broadcasting (DAB) systems are known in Europe. It is a digital broadcasting system proposed for audio and data service for the purpose of digitizing AM and FM broadcasting.

1 is a view schematically showing the structure of a DAB system.

Referring to FIG. 1, the DAB system includes a plurality of DAB transmitters 112, 122, 132, and 142 having one or more service areas and managing the service areas 110, 120, 130, and 140, respectively. That is, each of the DAB transmitters 112, 122, 132, and 142 provides a digital broadcast service to MSs within the area that they manage. In this case, the DAB transmitters 112, 122, 132, and 142 transmit DAB frames to MSs, and the serviceable areas 110, 120, 130, and 140 are determined by the transmission power of the DAB transmitters 112, 122, 132, and 142. ) Is determined.

In this DAB frame, each DAB transmitter 112, 122, 132, 142 may transmit the same DAB frame, or may transmit another DAB frame to MSs for each DAB transmitter 112, 122, 132, 142. For example, suppose that DAB transmitter 1 112, DAB transmitter 3 132, and DAB transmitter 4 142 transmit DAB frame 1, and DAB transmitter 2 122 transmits DAB frame 2. The DAB transmitters 112, 122, 132 and 142 transmit each DAB frame to MSs located in the service areas 110, 120, 130 and 140 that they manage. In addition, MSs located in the service area 1 (110), the service area 3 (130), and the service area 4 (140) among the service areas (110, 120, 130, 140), that is, the same DAB frame from the DAB transmitters (112, 132, 142), that is, The DAB frame 1 is received.

In this case, when the MS1 114 located in the service area 1 110 and receiving the DAB frame 1 from the DAB transmitter 1 112 moves to the service area 3 130, the service area 3 130 manages the service area 3 130. Since DAB Transmitter 3 132 also transmits DAB Frame 1, MS1 114 receives the same DAB Frame 1 from DAB Transmitter 3 132 as in Service Area 1 110. That is, even though the MS1 114 moves from the service area 1 110 to the service area 3 130, the DAB transmitters 112 and 132 that manage the service areas 110 and 130 are equally configured to select the DAB frame 1 from the MS1. Since it is transmitted to the 114, the MS1 114 continuously receives the digital broadcasting service provided from the DAB transmitter 1 112 from the DAB transmitter 3 132 without interruption.

On the other hand, when the MS2 116 located in the service area 1 110 and receives the DAB frame 1 from the DAB transmitter 1 112 moves to the service area 2 120, the service area 2 120 is managed. Since DAB transmitter 2 122 transmits DAB frame 2, MS2 116 receives DAB frame 2 from DAB transmitter 2 122. Accordingly, the MS2 116 cannot receive the DAB frame 1 received from the DAB transmitter 1 112 of the service area 1 110. In other words, when the MS2 116 moves from the service area 1 110 to the service area 2 120, the DAB transmitter 2 122 transmits a DAB frame different from the DAB transmitter 1 112 and thus, the MS2 ( 116 cannot continuously receive the digital broadcasting service provided from the DAB transmitter 1 112 which manages the service area 1 110.

As described above, in the digital broadcasting system, when the MS moves between service areas, especially when moving between service areas managed by transmitters transmitting different broadcast frames, the MS receives different broadcast frames from each transmitter. Accordingly, there is a problem in that the MS cannot continuously provide a digital broadcasting service without interruption.

Accordingly, an object of the present invention is to provide a method and system for handover so that a MS subscribed to a digital broadcasting system can continuously receive a broadcast service without interruption when moving between different service areas.

A method for handover in a digital broadcasting system comprising a receiver according to the present invention and a transmitter for transmitting a broadcast frame for providing a broadcast service to the receiver, when the receiver detects that the handover should be performed, the broadcast is performed. Searching for a frame providing the same broadcast service as the at least one currently provided broadcast service in a frame list included in the frame; and a frame for providing the same broadcast service as the at least one currently provided broadcast service is not found. If it is determined that the handover is impossible, and a frame providing the same broadcast service as the at least one currently provided broadcast service is searched for, the same broadcast service as the searched at least one currently provided broadcast service is searched for. The priority of the frames Determining one frame based on the region identifier information, selecting one frame among the frames providing the same broadcast service as the searched at least one currently provided broadcast service according to the determined priority, and then providing the selected frame And handing over to the transmitter.

In addition, a system for handover in a digital broadcasting system including a receiver according to the present invention and a transmitter for transmitting a broadcast frame for providing a broadcast service to the receiver, the system for handover, the strength of the received signal of the broadcast frame If it is detected that the handover is to be detected, the frame list included in the broadcast frame is searched for a frame providing the same broadcast service as at least one currently provided broadcast service, and the at least one currently provided broadcast service If the frame providing the same broadcast service is not found, the handover is determined to be impossible, and if the frame providing the same broadcast service as the at least one currently provided broadcast service is found, the searched at least one Same as the broadcasting service currently provided A priority of a frame providing a broadcast service is determined based on region identifier information, and one frame is selected from among frames that provide the same broadcast service as the searched at least one currently provided broadcast service corresponding to the determined priority. After selection, the receiver to perform the handover to a transmitter providing the selected frame.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, only parts necessary for understanding the operation according to the present invention will be described, and the description of other parts will be omitted so as not to obscure the gist of the present invention.

According to the present invention, when a user or mobile station (MS, hereinafter referred to as 'MS') moves between broadcast service areas, the MS continuously provides a broadcast service provided in the current service area without interruption. We suggest a handover plan to receive. In particular, when the MS moves between service areas managed by transmitters transmitting different broadcast frames in a digital broadcasting system, the MS proposes a handover scheme so that the MS can continuously receive the broadcast service without interruption. do.

In the following description, the digital broadcasting system will be described based on a digital audio broadcasting (DAB) system among the digital broadcasting systems, but the present invention is not limited thereto. That is, the present invention is applicable to all digital broadcasting systems including the digital video broadcasting and the digital multimedia broadcasting system as well as the DAB system. In addition, for convenience of description, it is assumed that the digital broadcasting system transmits and receives signals in an Orthogonal Frequency Division Multiplexing (OFDM) scheme, but according to the embodiment of the present invention. The present invention can be applied to all digital broadcasting systems that transmit and receive signals through other communication methods as well as methods.

FIG. 2 is a diagram schematically illustrating a structure of a DAB frame transmitted from a DAB transmitter providing a broadcast service to a receiver of MSs in a DAB system according to an embodiment of the present invention.

Referring to FIG. 2, the DAB frame includes a sync channel region 210, a fast information channel (FIC) region 230, and a main service channel (MSC). Channel, hereinafter referred to as 'MSC'). In addition, the DAB frame is composed of one null symbol and 76 symbols. When the DAB system is an OFDM system, that is, when a signal is transmitted and received by the OFDM system between the DAB transmitter and MSs, The first OFDM symbol is a null symbol, and the second OFDM symbol is a phase reference symbol (PRS). Since no signal is transmitted in the null symbol of the first OFDM symbol, the energy during the null symbol period is lower than that of other symbols. Accordingly, the receiver receiving the symbol can find the start time point of the DAB frame by finding the null symbol period by using an energy detection algorithm. In addition, the PRS of the second OFDM symbol transmits phase information necessary for data demodulation.

These two symbols, that is, the channel constituted by the null symbol and the PRS, are the synchronization channels, and the synchronization channel region 210 is the two symbol intervals of the fastest part of the DAB frame. The next area of the sync channel area 210 is the FIC area 230 and three symbols of the FIC area 230 are used to transmit the FIC. The remaining 72 symbols of the 76 symbols are used to transmit the MSC of the MSC region 750.

The FIC region 230 includes a plurality of fast information blocks (FIBs) 231, which are transmitted through one FIC region 230. Are determined by the transmission mode. In other words, four transmission modes are possible, including 12 FIBs 231 in transmission mode 1, three FIBs 231 in transmission mode 2, and four in transmission mode 3. The FIB 231 includes six FIBs 231 in the transmission mode 4.

In addition, the FIBs 231 are 256 bits each, and the 256-bit FIBs 231 are a 240-bit FIB data region 233 and a 16-bit cyclic redundancy check (CRC). It is composed of a CRC region 235 including a bit). In addition, the FIB data area 233 includes a plurality of Fast Information Groups (FIGs) (hereinafter referred to as 'FIGs') 237, and each FIG 237 is connected to the FIG header 239. It consists of the FIG data section area 245.

The FIG header 239 includes a FIG type region 241 indicating a type of data transmitted through the FIG data interval region 245 and a FIG length region 243 indicating a length of the FIG data interval region 245. Can be divided into In this case, the FIGs 237 are transmitted through the FIB data area 233, and when the total length of the FIGs 237 to be transmitted is not equal to the length of the FIB data area 233, the end indicator area 247 ) To indicate the end point of a valid data interval and fill the remaining padding with "0". Here, the end indicator region 235 is 8 bits, and all of them are "1".

In addition, the MSC area 250 includes a common interleaved frame (CIF) 251 as an area in which data to be transmitted is located, and the number of CIFs 251 is It is determined by the transmission mode. That is, the transmission mode 1 includes four CIFs 251, the transmission mode 2 includes two, the transmission mode 3 includes one, and the transmission mode 4 includes two CIFs 251. The included CIFs 251 are transmitted to one MSC region 250. In addition, the CIF 251 is composed of 55296 bits of subchannels 253. At this time, if the subchannels 253 to be transmitted do not fill all of the 55296 bits of the CIF 251, the remaining padding is filled with “0”.

The FIC area 230 of the DAB frame includes an FIC data service signal for transmitting traffic information or an emergency message, multiplex configuration information (MCI), and service information (SI :). Service information, hereinafter referred to as "SI"), and the like. The MCI includes position and length information of each subchannel 253 included in the MSC region 250 and information on channel coding rates of the subchannels 253. In addition, when various broadcast services are provided through one DAB frame, the MCI includes information on a connection relationship such as which service components each broadcast service is connected to. In addition, the MCI includes information such as on which subchannels each service component is transmitted when each service is connected to one or various service components, and the reconstructed information when the multiplexed configuration information is reconfigured. It includes.

The SI informs information not included in the aforementioned MCI, that is, information on each service. In more detail, the SI includes information related to a broadcast service that can be provided by a currently transmitted DAB frame with information about a service component, information about time and country, program related information, and the like. In addition, the SI may include frequency information (FI), transmitter identifier information (TII), and transmitters of other service areas. DAB frame information to be transmitted (OFI: Other Frame Information, hereinafter referred to as 'OFI'), service linking information (SLI: hereinafter, referred to as 'SLI'), and information about regional boundaries (RDI: Other DAB frames such as Region Definition Information, hereinafter referred to as 'RDI'), and local service area information (LSAI: Local Service Area Information, hereinafter referred to as 'LSAI') and broadcast service information. do.

In this case, the FIC data service signal refers to a signal of a service for transmitting data, not control information, through the FIC region 230. A paging and traffic message channel (TMC) is included in the FIC data service. , Hereinafter referred to as 'TMC'), an emergency warning system (EWS), and the like. In addition, the case where the data service is transmitted through the FIC region 230 is referred to as a fast information data channel (FIDC).

The MCI, the SI, and the FIDC are transmitted through the FIG data section region 245, which is a data section of FIG 237, and as described above, the FIG header (FI) corresponds to the data transmitted by the FIG data section region 245. Different values are set in 239). Accordingly, the receiver receiving the DAB frame, that is, the MS, may determine the type of data transmitted to the FIG data interval region 245 through the FIG header 239. In addition, the sizes of the FIG 237 are determined according to the amount of data to be transmitted in the FIG 237, and information on the size of each FIG 237 may also be known through the FIG header 239. These FIG 237 are multiplexed by having various forms, and the multiplexed FIGs 237 constitute one FIB 231 and one FIC 230 by the FIB 231.

In addition, the MCI and SI need to be aware that the MS receives and demodulates the DAB signal to provide a digital broadcasting service to the user. Demodulates each broadcast service and then provides a broadcast service selected by the user.

3A and 3B schematically illustrate an SI structure of a DAB frame in a DAB system according to an embodiment of the present invention. As described above, the SI includes information related to each broadcast service. Hereinafter, an SI structure including service information of a frame different from FI and LSAI and RDI among the information will be described.

3A and 3B, the FI 310 of the SI includes frame identifier (FId) information of neighboring DAB frames and frequency information used by each DAB frame. do. In detail, the FI 310 is divided into a plurality of FI areas 311, and the FI area 311 indicates a service area in which each DAB frame is transmitted, that is, an area indicating location information of each DAB frame. An identifier (Region Identification) area 313, a plurality of FI list areas 317, and an area 315 indicating the size of the FI list area 317. The FI list area 317 includes an FId area 319 of each DAB frame, an R & M area 321, a continuous flag area 323, a frequency list area 327 of each DAB frame, and the frequency. It consists of an area 325 representing the size of the list.

Here, the region identifier included in the region identifier region 313 indicates that frames having the same identifier as information representing the division of the service region are the same service region. In the FI 310, the FIG type region is set to "0" in the FIG header, and the extended section of the FIG data interval region is set to "21" and transmitted. The MS that receives the FI 310 constructs a frame list using the FI 310.

The service information of another frame of the SI (OFSI: hereinafter referred to as 'OFSI') 330 is a service identifier (SId) of each frame (hereinafter referred to as 'SId'). Information, that is, identification information of a broadcast service provided by each frame. The OFSI 330 is divided into a number of other frame service (OFS) areas 331 representing OFSIs. The OFS areas 331 are divided into frames. SId region 333 indicating SId having, Rfa region 335, FId regions 339 indicating identifiers of respective frames for providing a broadcast service, and indicating the number of FIds included in the FId regions 339. It consists of an area 337.

When the MS receives such OFSI 330, the MS recognizes the FId of the frame providing the same broadcast service as the broadcast service currently selected and provided through the OFSI 330. Accordingly, the MS searches in the frame list configured using the FI 610 whether the same FId as the FId recognized by the OFSI 330 exists. At this time, the OFSI 330 is transmitted with the FIG type region set to "0" in the FIG header, and the extended section of the FIG data interval region set to 24. Using the transmitted OFSI 330, the MS obtains information on candidate frames.

In addition, the LSAI 350 of the SI includes location information of a corresponding service area of a DAB frame providing a current broadcast service. In more detail, the LSAI 350 is divided into a plurality of areas 351 representing LSAI, and the areas 351 are an SId area 353 and an Rfa area indicating an SId of a frame providing a current service. 355, a region identifier region 357 indicating what service region the current service has, that is, region information of the currently provided broadcast service region. Here, the area identifier area 357 is composed of an upper area 359 and a lower area 361.

When the MS receives the LSAI 350, the MS recognizes the region identifier information to which each SId belongs through the LSAI 350. Also, the LSAI 350 is transmitted with the FIG type region set to "0" in the FIG header, and the extended section of the FIG data interval region set to 23. Using the transmitted LSAI 350, the MS recognizes in which region the frame transmitted by the transmitter providing the current service belongs, that is, in which service region it is currently located.

The RDI 370 includes actual position information of each region identifier of the peripheral DAB frames. In other words, the RDI 370 is divided into a plurality of regions 371 representing a region boundary, and the regions 371 are a GATy region 373, a G / E flag region 375, and a region identifier region 377. ), And geographic region 383. Here, the region identifier region 377 is composed of an upper region 379 and a lower region 381, and the geographic region 383 includes a region 385 indicating latitude, a region 387 indicating longitude, and the region 387. It consists of regions 389 and 391 which can respectively extend latitude and longitude.

When the MS receives such an RDI 370, the MS knows via the RDI 370 which location identifier of each area identifier of the surrounding DAB frames actually represents. That is, as the RDI 370 has the latitude and longitude of each region identifier, the RDI 370 recognizes the actual geographical position of the region identifier. In addition, the RDI 370 is transmitted with the FIG type region set to "0" in the FIG header, and the extended section of the FIG data interval region set to 11.

When the MS recognizes the local information of the surrounding frame, that is, the location information, the MS already recognizes the relationship between each region identifier and the FId, and since the MS has already selected a candidate frame through the relationship between the FId and the SId, the MS Recognize regional information of candidate frames having the same SId as the SId of the currently provided service. In addition, since the MS already knows the location of the region where the current frame is transmitted, the MS recognizes how the candidate frames are related to distance with the frame currently received.

As a result, the MS sets a candidate frame close to the frame currently providing the broadcast service to the candidate among the candidate frames as a high priority frame, and sequentially sets the priority of the candidate frames according to the proximity. The frame to be handed over is selected according to the set priority, and this is a candidate frame to be handed over from the highest priority frame. That is, the handover object is sequentially subject to the order of the prioritized frames, and the MS determines whether the handover is performed based on the strength of the received signal of the candidate frame.

As described above, the DAB frame having such a structure can provide various broadcast services in one frame, and one or more other services are multiplexed and transmitted in one frame. That is, the MS provides an audio service, a video service, a data service, and the like, multiplexed with one frame.

4 is a diagram schematically illustrating multiplexing of a broadcast service in a DAB frame in a DAB system according to an embodiment of the present invention. For convenience of explanation, it is assumed that one DAB frame is DAB frame 1 401.

Referring to FIG. 4, the DAB frame 1 401 has alpha 1 radio 403, beta radio 405, and alpha 2 radio 407 services. The services are composed of a plurality of service components 409, 411, 413, 415, 417 and 419, and the service components 409, 411, 413, 415, 417 and 419 may be a plurality of service components in one service. More specifically, alpha 1 radio 403 includes service components of audio 1 409, alpha-TMC 411, alpha-SI 413, and alpha 2 radio 407 is audio 1 403. , Service components of Audio3 419, Alpha-TMC 411, and Alpha-SI 413. The beta radio 405 also includes service components of audio 2 415 and secondary-ry audio 417.

The services have a main service component, i.e., in the case of alpha 1 radio 403, audio 1 409 is the main service component, and in the case of alpha 2 radio 407, audio 1 409 and audio 3 ( The switching operation of 419 becomes one of the main service components. Accordingly, unlike the alpha 1 radio 403 having only one service component as the main service component, in the case of the alpha 2 radio 407, the main service component changes in time. In the case of the beta radio 405, audio 2 415 becomes the main service component. These service components 409, 411, 413, 415, 417, and 419 are each transmitted on one subchannel 423. The subchannels 423 transmitting the respective service components 409, 411, 413, 415, 417, and 419 constitute an MSC, and where the subchannels 423 are transmitted in the MSC can be known through MCI as described in FIG. 2. have.

As such, the DAB frame is transmitted to the MS by multiplexing multiple services. Accordingly, when two different DAB frames of DAB frame 1 and DAB frame 2 exist, the same service may exist in the two DAB frames. That is, when the MS moves between service areas in which different DAB frames are transmitted, if the same service exists in the DAB frames, the MS may continuously receive the currently provided service even if receiving the other DAB frame. Can be.

5 is a diagram schematically illustrating a structure of a DAB frame receiver of an MS receiving a DAB frame in a DAB system according to an embodiment of the present invention.

Referring to FIG. 5, the receiver includes an RF receiver 501, a measurer 503, a data demodulator 505, a control information processor 507, a data processor 509, and a controller 511.

The RF receiver 501 receives a broadcast signal transmitted from a transmitter, that is, a DAB frame, and the received signal is transmitted to the measurement unit 503 and the data demodulator 505. The measurement unit 503 measures the intensity of the received signal, and the intensity of the measured signal is transmitted to the controller 511. In addition, a predetermined threshold value is transmitted to the controller 511, and the threshold value is set to a minimum signal strength value necessary for demodulating the data received by the receiver. If the strength of the signal measured by the measurement unit 503 is less than the threshold value, the receiver cannot demodulate data normally received by the RF receiver 501. Here, the threshold value may be set differently according to the performance of the receiver, and may be previously determined by the system and transferred to the receiver. That is, the receiver receives the threshold value from the system, or the threshold value is set by the user according to the performance of the receiver and the set threshold value is transmitted to the control unit 511 of the receiver.

The controller 511 compares the signal strength transmitted from the measurement unit 503 with the threshold value. If the signal strength is smaller than the threshold, the RF receiver 501 determines that a signal of a frame currently being serviced is weak and receives a signal for other candidate frames. In this case, the other candidate frames include a frame of a service currently being received, and the RF receiver 501 needs information about other candidate frames in order to receive the other candidate frames. Accordingly, the controller 511 receives control information of other candidate frames from the control information processor 507 and controls the RF receiver 501 to receive other candidate frames using the control information.

The data demodulator 505 demodulates data input from the RF receiver 501, and the demodulated data is divided into MSC data and FIC data. That is, the data demodulator 505 demodulates the input data into the MSC data and the FIC data, transfers the demodulated MSC data to the data processing unit 509, and transfers the FIC data to the control information processing unit 507. do. The control information processor 507 demodulates the MCI and the SI from the input FIC data and transmits the demodulated MCI and SI to the data processor 509. The data processor 509 receiving the MCI, SI and MSC data decodes the MSC data for each service using the control information, that is, the MCI and the SI.

In addition, the SI data is transmitted to the controller 511, and the controller 511 receiving the SI data recognizes information on the other candidate frames using the SI data. As the controller 511 recognizes information on other candidate frames through the SI data, the controller 511 determines which candidate frame to handover to when the MS moves to another service area. The information is transmitted to the RF receiver 501. The RF receiver 501 which has received the determined information from the controller 511 changes the frequency of the RF according to the information transmitted from the controller 511, and thus the receiver makes a new frame to handover through the changed frequency. Receive

6 is a diagram illustrating an operation process of a DAB frame receiver of an MS receiving a DAB frame in a DAB system according to an embodiment of the present invention.

Referring to FIG. 6, in step 601, when a receiver receives a broadcast signal, that is, a DAB frame through the RF receiver 501, the receiver measures the strength of the received signal. Then, in step 603, the strength of the measured signal is compared with a preset threshold value, and if the strength of the measured signal is greater than the threshold value, since handover is unnecessary, the received signal is periodically received while decoding. The signal strength is continuously compared and judged. On the other hand, if the strength of the measured signal is less than the threshold value, handover is required and the flow proceeds to step 605.

In step 605, the receiver searches for candidate frames in a frame list included in the received frame. Here, as described above, the candidate frame is a frame that provides the same service as the currently selected service among frame lists already received by the receiver through the frame, and the frame list is obtained by using the SI received by the receiver through the FIC. It is every frame from which information can be obtained. If there is no candidate frame including the same service as the currently selected service among the frame lists, handover is impossible, and the flow proceeds to step 613 to terminate the currently provided service. Meanwhile, if there is a candidate frame including the same service as the selected service in the frame list, the receiver finds the RDI in the SI received through the FIC. Since the RDI is configured with information about latitude and longitude of the region identifier, the region identifier becomes an identifier for locally assigning frames, and frames having the same region identifier are likely to be adjacent to each other. Accordingly, since the region information of the region identifier is recognized through the RDI, the positions of the frames designated as the candidate frames can be determined.

Then, in step 607, the receiver determines the priority of candidate frames using the determined positions of the frames, that is, using RDI. That is, the receiver determines the frames having a shorter distance from the current frame as high priority frames and the frames having a long distance as low priority frames. Then, the receiver first selects a frame having a high priority corresponding to the priority of the frames and proceeds to step 609. In step 609, the receiver measures the strength of the received signal of the selected frame and then compares the strength of the measured signal with a threshold. If the signal strength is greater than the threshold as a result of the comparison, the process proceeds to step 611. In step 611, the receiver determines handover to the selected frame.

On the other hand, if the signal strength of the comparison result is less than the threshold value, the process proceeds to step 615, in step 615, the receiver determines whether a frame having the next priority exists. In this case, if a frame having a next priority does not exist, the receiver cannot receive a signal of a frame larger than a threshold value and thus handover is impossible. Therefore, the receiver proceeds to step 613 to terminate the currently provided service. On the other hand, if there is a frame having the next priority, that is, if there is a frame to be measured, the process proceeds to step 617. In step 617, the receiver selects a new frame by switching to a frame identifier having the highest priority among existing frames. Then, after measuring the strength of the received signal for the selected frame, the process proceeds to step 609 to compare the measured intensity of the received signal and the threshold again. If the received signal is greater than the threshold as a result of the comparison, the process proceeds to step 611 to determine the handover to the selected frame. On the other hand, if the strength of the received signal of the selected frame is less than the threshold value and proceeds to step 615 again to perform the above-described process again.

In this way, the receiver roughly determines the positions of the candidate frames using RDI, determines the priority of the candidate frames according to the determined positions, and then selects the frames to be handed over according to the priorities.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited by the illustrated embodiments, but should be determined by the scope of the appended claims and equivalents thereof.

According to the present invention as described above, when the MS moves between service areas, by performing a handover to the frame providing the same broadcast service as the currently provided broadcast service, the currently provided broadcast service can be continuously received without interruption. Can be. In addition, the present invention can perform handover quickly by determining the frame to be handed over by setting the priority of the frames based on the position information of the surrounding frames.

Claims (20)

A method for handover in a digital broadcasting system comprising a receiver and a transmitter for transmitting a broadcast frame for providing a broadcast service to the receiver, Searching for a frame providing the same broadcast service as at least one currently provided broadcast service in a frame list included in the broadcast frame when the receiver detects that the handover should be performed; Determining that the handover is impossible when a frame providing the same broadcast service as the at least one currently provided broadcast service is not found; When a frame providing the same broadcast service as the at least one currently provided broadcast service is searched, the priority of the frame providing the same broadcast service as the searched at least one currently provided broadcast service is based on region identifier information. The process of determining Selecting one frame from among frames providing the same broadcast service as the searched at least one currently provided broadcast service according to the determined priority, and then handing over to the transmitter for providing the selected frame; Handover method. delete delete The method of claim 1, The determining of the priority may include determining that a frame closer to the position of the broadcast frame has a higher priority among frames providing the same broadcast service as the searched at least one currently provided broadcast service. Handover method. The method of claim 1, And the area identifier information includes latitude and longitude information of a frame providing the same broadcast service as the found at least one currently provided broadcast service. The method of claim 1, The selecting of the one frame may include comparing a received signal strength of a frame providing the same broadcast service and a preset threshold value with the at least one currently provided broadcast service sequentially according to the priority. And selecting the one frame according to the comparison result. The method of claim 6, The step of comparing the intensity of the received signal of the frame providing the same broadcast service with the searched at least one currently provided broadcast service and a preset threshold value may include: searching for the at least one currently provided broadcast service; When the frame having the highest priority is unselected by comparing the received signal strength of the frame having the highest priority and the threshold value among the frames providing the same broadcast service, the received signal strength of the frame having the next priority Handover method characterized in that the process of comparing the threshold value. The method of claim 6, The threshold value is a handover method, characterized in that the value of the minimum signal strength for demodulation of the data received by the receiver. The method of claim 1, The broadcast frame includes information indicating that at least one broadcast service provided by the broadcast frame, identification information of the broadcast service, and list information of a frame providing the same broadcast service as the at least one currently provided broadcast service. Handover method characterized in that it comprises a. 10. The method of claim 9, List information of a frame providing the same broadcast service as the at least one currently provided broadcast service may include identification information, frequency information, location information of a frame providing the same broadcast service as the at least one currently provided broadcast service, and And at least one identification information of a broadcast service provided by a frame providing the same broadcast service as the at least one currently provided broadcast service. A system for handover in a digital broadcasting system comprising a receiver and a transmitter for transmitting a broadcast frame for providing a broadcast service to the receiver, If it is detected that the handover should be performed by measuring the strength of the received signal of the broadcast frame, the system searches for a frame providing the same broadcast service as at least one currently provided broadcast service in a frame list included in the broadcast frame, When the frame providing the same broadcast service as the at least one currently provided broadcast service is not found, it is determined that the handover is impossible, and the frame providing the same broadcast service as the at least one currently provided broadcast service is searched. In this case, the priority of a frame providing the same broadcast service as the searched at least one currently provided broadcast service is determined based on region identifier information, and the searched at least one currently provided search is corresponding to the determined priority. Same broadcast as broadcast service And a receiver configured to select one frame from among frames providing a service and to perform the handover to a transmitter providing the selected frame. delete delete 12. The method of claim 11, The receiver determines the priority to have a higher priority as the frame closer to the position of the broadcast frame among the frames providing the same broadcast service as the searched at least one currently provided broadcast service. system. 12. The method of claim 11, And the area identifier information includes latitude and longitude information of a frame providing the same broadcast service as the found at least one currently provided broadcast service. 12. The method of claim 11, The receiver compares the received signal strength of a frame providing the same broadcast service with the searched at least one currently provided broadcast service sequentially and the preset threshold value according to the priority, and then corresponds to the comparison result. And select the one frame. 17. The method of claim 16, The receiver has the highest priority by comparing the received signal strength of the frame having the highest priority among the frames providing the same broadcast service as the searched at least one currently provided broadcast service and the threshold value. And when the frame is unselected, comparing the received signal strength of the frame having the next priority with the threshold. 17. The method of claim 16, The threshold value is a handover system, characterized in that the minimum signal strength for demodulation of data received by the receiver. 12. The method of claim 11, The broadcast frame includes information indicating that at least one broadcast service provided by the broadcast frame, identification information of the broadcast service, and list information of a frame providing the same broadcast service as the at least one currently provided broadcast service. Handover system characterized in that it comprises a. 20. The method of claim 19, List information of a frame providing the same broadcast service as the at least one currently provided broadcast service may include identification information, frequency information, location information of a frame providing the same broadcast service as the at least one currently provided broadcast service, and And at least one identification information of a broadcast service provided by a frame providing the same broadcast service as the at least one currently provided broadcast service.

Images