KR20090069060A - Method for a handover in digital multimedia broadcasting - Google Patents

Abstract

A method for a handover in a DMB(Digital Multimedia Broadcasting) is provided to supply a handover algorithm for the change of channel environment in a DMB network. Measured is the reception quality related to the first data of a high speed channel that is received from a first broadcasting channel currently connected(S1104), and it is checked over whether or not a handover is necessary by being compared with a preset first quality reference(S1106). A target channel is selected based on pre-obtained service relationship information(S1112). The reception quality of the second data of high speed information channel received from the target channel is compared with the second quality reference(S1116). It is determined whether or not the switching to the target channel is determined(S1118).

Description

Method for a Handover in Digital Multimedia Broadcasting}

The present invention relates to a method for performing handover in a digital multimedia broadcasting network. More specifically, it is more accurate and faster to perform a handover by using a reception quality of a fast information channel instead of an electric field strength in a digital broadcasting receiver. The present invention relates to a digital multimedia broadcasting handover method and a control apparatus thereof.

Recently, the viewing pattern of TV is greatly changed due to the convergence of broadcasting and communication technologies. The advent of Digital Multimedia Broadcasting (DMB), which enables users to enjoy clear broadcasts on high-speed trains, enables the viewing of personalized broadcasts that are not limited by time and space.

In other words, the advent of DMB is no longer needed to hurry up in front of the TV in the living room to watch dramas or sports broadcasts.

In Korea, terrestrial DMB has recently been activated, starting with the initial satellite DMB. Terrestrial DMB refers to providing a digital mobile multimedia broadcasting service to a subscriber mobile receiver using a terrestrial repeater.

Here, the terrestrial repeater may be assigned different frequencies for each zone, and the area serviced by the terrestrial repeater, that is, cell coverage is limited.

To ensure service continuity, the DMB receiver must perform DMB handover when moving out of the cell coverage of the currently connected terrestrial repeater to the service area of another terminator.

For DMB handover, the DMB receiver may scan the DMB signals received from the adjacent terrestrial repeater and check the currently available DMB signals. At this time, the DMB receiver processes the DMB handover in consideration of the signal strength, service ID, ensemble ID, etc. of the received DMB signal.

However, the conventional DMB receiver simply determines whether handover is necessary according to the reception field strength of the currently connected broadcast channel, so that frequent handover may occur in a fast bursting fading channel environment. . Accordingly, the channel switching occurs frequently, so that broadcast reception is frequently disconnected.

An object of the present invention for solving the problems of the prior art as described above is to provide a handover algorithm resistant to changes in the channel environment in a digital multimedia broadcasting network.

Another object of the present invention is to provide a method for performing handover in a digital broadcast receiving apparatus determining whether to initiate a handover by using a reception quality of a fast information block included in a fast information channel. It is.

Still another object of the present invention is to provide a digital broadcast receiving apparatus capable of controlling a time point at which a channel is completely switched by monitoring a time point of selecting a target channel to perform handover using a predetermined quality control parameter and monitoring the quality of the selected target channel. It is to provide a method for performing handover in.

It is still another object of the present invention to provide a method for performing handover capable of supporting continuity of a broadcast service during handover.

It is still another object of the present invention to provide a method for performing handover in a digital multimedia broadcasting network capable of maintaining higher broadcast service quality by preventing unnecessary handovers from occurring frequently due to erroneous reception quality measurement.

According to an embodiment of the present invention, a method of performing handover in a digital broadcast receiving apparatus is disclosed.

A method for performing handover in a digital broadcast reception device according to an embodiment of the present invention includes a first step of measuring a first data reception quality of a fast information channel received from a currently connected first broadcast channel; A second step of determining whether handover is necessary by comparing the first data reception quality with a first preset quality criterion; A third step of selecting a target channel using previously obtained service relationship information when handover is necessary as a result of the determination; And a fourth step of determining whether to switch to the target channel by comparing a second data reception quality of the fast information channel received from the selected target channel with a preset second quality criterion.

According to another embodiment of the present invention, a digital broadcast receiving apparatus for performing a faster and more effective handover is disclosed.

According to an embodiment of the present invention, an apparatus for receiving digital broadcasting includes a block error check unit for checking whether a corresponding fast information block is error by using an error check code included in a channel decoded fast information block; A fast information block error rate calculation unit which receives an error check result from the block error check unit, calculates a fast information block error rate of a corresponding broadcast channel, and generates a predetermined event signal by comparing the calculated block error rate with a preset quality criterion. ; And a handover control unit configured to receive the event signal from the fast information block error rate calculator and determine whether to initiate a handover procedure and whether to switch to a target channel.

The present invention is a method for performing handover in a digital broadcasting receiver more accurately and faster by determining whether to initiate a handover by using a reception quality of a fast information block included in a fast information channel. There is an advantage in providing.

In addition, by measuring the data reception quality of the accurate fast information block in real time using a feature that is not time interleaved in the fast information block of the present invention, there is an advantage of preventing the degradation of broadcast service quality due to handover decision error.

In addition, the present invention has an advantage of providing a method for performing handover in a digital broadcast receiving apparatus that is strong in a fast fading channel environment by measuring actual data reception quality, not electric field strength.

In addition, the present invention has the advantage of providing a handover method that can support the continuity of the broadcast service when the handover.

In addition, the present invention is to provide a method of performing a handover capable of maintaining a higher broadcast quality of service by preventing unnecessary handovers from occurring frequently due to erroneous reception quality measurement.

Through the above advantages, the present invention can expect the effect that more viewers use the digital multimedia broadcasting service.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component.

The term and / or includes a combination of a plurality of related items or any item of a plurality of related items. The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise.

In this application, the terms "comprising" or "mounted" and "mounted" are intended to indicate that there is a feature, number, step, action, component, part, or combination thereof described on the specification, one Or other features or numbers, steps, operations, components, parts or combinations thereof in any way should not be excluded in advance.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art, and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

Other aspects, features, and advantages other than those described above will become apparent from the following drawings, claims, and detailed description of the invention.

Hereinafter, a method of performing a handover in a digital broadcast receiving apparatus and a preferred embodiment of the apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings and the contents described in the accompanying drawings, but the present invention is not limited or limited to the embodiments.

1 is a structure of a digital multimedia broadcasting network according to an embodiment of the present invention.

As shown in FIG. 1, a portable receiver with a DMB function (hereinafter, referred to as a "DMB terminal 110" or a business card) transmits the DMB broadcast signal transmitted by the broadcasting station 120 to the DMB base station 130 or the DMB repeater ( 140).

Here, the DMB repeater 140 solves the shadow area problem and amplifies and transmits a broadcast signal received from the DMB base station 130 to expand cell coverage for a broadcast service.

The DMB terminal 110 disclosed in the present invention may include a mobile phone, a PDA, a notebook computer, a vehicle receiver, etc. equipped with a DMB function.

The broadcast station 120 encodes and multiplexes the previously generated broadcasting content in a manner defined in the DMB broadcasting standard, where the wired channel may be configured using a coaxial cable or an optical cable. Transmit to the DMB base station 130 via a radio channel, eg, a broadcast satellite.

In addition, the broadcasting station 120 may receive the processed content from the broadcast content provider 160 that processes the content to be suitable for a specific broadcast service.

In particular, the broadcast signal may include not only user data but also service relationship information in which mutual mapping relationships between ensemble, frequency, and service for DMB handover are defined.

Definitions and interrelationships for the ensemble, frequency, and service will be described in detail with reference to FIGS. 3 to 6 to be described later.

The return channel is a bidirectional control channel established between the broadcasting station 120 and the DMB terminal 110 and may be set through a mobile communication system. In general, the mobile communication system may be composed of a switch, a base station controller, a base station for mobile communication. A detailed description of the mobile communication system is not an essential component for describing the idea disclosed by the present invention and will be omitted below.

According to the present invention, the DMB terminal 110 initiates a handover procedure when the data reception quality of the fast information channel of the currently tuned broadcast channel does not satisfy a preset threshold. More specifically, the DMB terminal 110 may determine whether to initiate a handover based on an error rate of the fast information block included in the fast information channel.

When the handover procedure is started, the DMB terminal 110 selects a frequency to be searched by using relation information between the pre-obtained ensemble, service, and frequency, and currently tuned service among at least one service corresponding to the selected frequency. Check whether there is a channel capable of supporting the continuity of. If present, the DMB terminal 110 performs a handover to a channel capable of supporting the continuity of the service.

Here, the relation information between the ensemble, the service, and the frequency may be generated using at least one fast information group (FI) included in the fast information block, and may be generated in a predetermined recording area of the DMB terminal 110. maintain.

2 is an example of frequency allocation of a DMB service according to an embodiment of the present invention.

Referring to FIG. 2, a general DMB service may cover a relatively large area through one frequency band. For example, FIG. 2 shows that Chungcheongnam-do and Chungcheongbuk-do are assigned the 11th frequency and Jeollanam-do the eighth frequency.

In particular, adjacent frequencies may overlap each other, and handover may occur frequently in the overlapped periods. For example, the DMB terminal located at the border region of Chungcheongnam-do and Gyeonggi-do may perform handover in a section where the eighth frequency, the twelfth frequency, and the eleventh frequency overlap.

In particular, the DMB service network shown in FIG. 2 reuses frequencies so that the same frequencies do not overlap in order to maximize frequency use efficiency. For example, it can be seen that the thirteenth frequency allocated to Gangwon-do is used in some regions of Jeju Island.

In general, when a conventional DMB terminal is located in a region where a plurality of frequencies overlap, if it is determined that handover is necessary, electric field strength or signal to noise ratio for all frequency bands used in the region is determined. ), And handover was performed using the measurement result. However, even if the reception level is good due to the effects of multi-path, fading, adjacent channel interference, co-channel interference, etc., the field strength may actually generate a large amount of errors in the received data block.

In addition, even in the case of the signal-to-noise ratio, the SNR for providing a certain level of quality reference may be different according to the moving speed of the digital broadcast receiving apparatus. It can reduce handover performance.

In contrast, according to an exemplary embodiment of the present invention, the FIB error rate used as a reference quality criterion for determining whether to initiate a handover is a value calculated based on actual received data, and the digital broadcast receiver acquires phase synchronization. First, the FIB included in the fast information channel is decoded to check whether there is an error.

In particular, the fast information channel has a simple receiver structure because no time interleaving is performed, and thus the fast information channel can be used as a reference channel for quickly and accurately determining a channel quality state of a current access channel.

Accordingly, the handover control method based on the FIB error rate according to the present invention can prevent the handover to be performed on a channel having a low actual reception quality.

3 is a view for explaining a DMB frequency allocation method according to an embodiment of the present invention.

As shown in FIG. 3, the frequency bands allocated for the DMB service are channel 8 310 and channel 12 320. Here, each channel is divided into an A band, a B band, and a C band, and a predetermined guard band is allocated between each band to avoid inter-frequency interference.

For example, channel 12 320 is divided into 12A band 321, 12B band 322, and 12C band 323, and broadcast service providers for each band may be allocated MBC, KBS, and SBS, respectively. .

The broadcast service provider may configure various broadcast service channels by subdividing the allocated bands. For example, the KBS may provide an ensemble of KBS star, KBS heart, and KBS TTI through the allocated 12B band 322. Here, the ensemble may be uniquely identified by the ensemble identifier as a set of services transmitted in a specific frequency band.

The services constituting the ensemble include audio, video, and data services, and may be composed of one or more service components.

The service is identified by the service identifier, and the DMB terminal preferably maintains the continuity of the service by transitioning to a frequency where the same service as the service currently being viewed is provided upon handover between frequencies.

4 is a diagram for explaining inter-frequency handover for the same ensemble according to an embodiment of the present invention.

Here, the same ensemble means that a set of services provided at different frequencies are the same. That is, the ensemble identifiers are the same.

Of course, services corresponding to each other included in two identical ensembles have the same service identifier.

Accordingly, in order to perform handover between frequencies having the same ensemble, relationship information between the ensemble and the frequencies is required.

Referring to FIG. 4, the ensemble identifier 0xE084 of the 11B band allocated to the Chungcheong region is the same as the ensemble identifier 0xE084 of the 12B band allocated to the Chonbuk region. Therefore, the DMB terminal moving from the Chungjeong area to the Jeonbuk area needs to shift the reception frequency from the 11B band to the 12B band while maintaining the current service when handover between frequencies.

5 is a diagram for explaining handover between frequencies for different ensembles according to an embodiment of the present invention.

As shown in FIG. 5, it can be seen that the ensemble identifier 0xE044 corresponding to the 12B band of the Seoul area is different from the ensemble identifier 0xE084 corresponding to the 11B band of the Chungcheong area.

That is, it can be seen that the combination of services provided in the Seoul area and the Chungcheong area is different from each other. However, there is the same service in each ensemble, for example KBS star and KBS TTI.

When performing an inter-frequency handover to a region where the ensemble is different, the DMB terminal checks whether the same service as the service currently being viewed in the serving cell 510 is served by the target cell 520.

As a result of the check, when the same service is supported by the target cell 520, the DMB terminal transitions to the frequency 11B corresponding to the target cell 520 while maintaining the service provided to the serving cell 510.

Therefore, when different ensembles and the same service identifier exist, the DMB terminal may perform handover between frequencies by using mapping information about [ensemble: frequency] and [service: ensemble].

FIG. 6 is a diagram for describing a handover method between frequencies in a case where frequencies, ensembles, and services are different from each other according to an embodiment of the present invention.

As shown in FIG. 6, it can be seen that the ensemble identifier and service identifier allocated to the 11C band of the Chungcheong region are different from the ensemble identifier and service identifier allocated to the 12C band of the Jeonbuk region.

When performing an inter-frequency handover to a region where the ensemble is different, the DMB terminal checks whether the same service as the service currently being viewed in the serving cell 610 is serviced by the target cell 620.

As a result of the check, when the same service is not supported by the target cell 620, the DMB terminal checks whether a service composed of the same service component as the currently provided service exists in the target cell 620.

As a result of the check, if there is a service configured with the same service component, the DMB terminal performs handover to the corresponding service of the target cell 620.

For example, when a DMB terminal moving from Chungjeong area to Jeonbuk area receives a TV service in Chungcheong area and performs handover, it performs handover to TV service in Jeonbuk area.

Therefore, when different ensembles are present and the same service identifier exists, the DMB terminal may perform handover between frequencies using respective mapping information for [ensemble: frequency], [service: ensemble], and [service: service]. Can be.

7 is a digital broadcast frame structure according to the present invention.

As shown in FIG. 7, one digital broadcast frame 700, a synchronization channel (SC) 710, a fast information channel (FIC) 720, and a main service channel (MSC) are shown. , 730).

The sync channel 710 is a channel that is transmitted first on the digital broadcast frame to transmit phase reference data of the broadcast signal.

The fast information channel 720, hereinafter referred to as "FIC 720", is composed of a plurality of fast information blocks 740, hereinafter referred to as "FIB 740," and is a main service channel. 730-hereinafter referred to as "MSC 730"-a channel that carries control information necessary to interpret the configuration.

Here, the control information is related to Multiplex Configuration Information (MCI), Service Information (SI), Conditional Access Management Information (CA), and Fast Information Data Channel (FIDC). Contains information.

The FIC 720 supports a transmission rate of 96 Kbps, multiplexed with the MSC 730, and then is OFDM modulated and transmitted to a digital broadcast receiver through a terrestrial link.

In particular, since the FIC 720 includes very important information related to the configuration and handover of the MSC 730, the FIC 720 is configured to decode the digital broadcast receiver more quickly and safely.

In general, in the wireless communication, time interleaving is performed between a transport block and a transport block in order to prevent a burst error caused by a sudden change in the channel environment. However, when receiving the time interleaved data, the receiving end should buffer until all interleaved data is received, and then de-interleaving should be performed on the buffered data.

For example, audio and video information transmitted by a broadcasting station are compressed using MPEG-4, respectively, and the compressed video block and the audio block are MPEG-2 processed, and then Read-Solomon Code having a length of 16 bytes is added. Thereafter, channel coded and time interleave data is multiplexed and OFDM modulated and transmitted over the air.

Unlike the MSC 730, the FIC 720 not only performs time interleaving for faster decoding at the receiving end, but also forward error correction (FEC), e.g., code rate, for a high level of error correction. Performs convolution encoding, where) is 1/3. In general, relatively low convolutional code rates such as 1/2, 5/6, etc. are provided for MSCs.

In addition, since a cyclic redundancy check (CRC) code for an error check is inserted for each FIB included in the FIC 720, the receiving end can accurately determine whether the corresponding FIB is in error.

In contrast, the MSC 730 is composed of a plurality of common interleave frames (CIF, 750), hereinafter referred to as "CIF 750," and the receiver structure compared to the FIC 720 because time interleaving is applied. Can be complicated and the decoding cost can be high.

8 is a detailed structure of a digital broadcast frame according to an embodiment of the present invention.

The structure of the digital broadcast frame currently supports four transmission modes (first to fourth transmission modes). The transmission frame period, the number of FIBs per transmission frame, and the number of CIFs per transmission frame are defined differently for each transmission mode.

8 illustrates a digital broadcast frame structure corresponding to the first transmission mode.

The digital broadcast frame of the first transmission mode has a Transmission Time Interval (TTI) of 96 ms, and one TTI includes 76 Orthogonal Frequency Division Multiplex (OFDM) symbols. Here, FIC and MSC are allocated 3 and 72 symbols, respectively, and the other one is used for the synchronization channel.

Each OFDM symbol has a symbol period of 1.246 ms, and consists of a guard interval of 0.246 ms and a data transmission interval of 1 ms.

The MSC consists of four CIFs, and one CIF consists of a total of 864 capacity units (CUs), where one CU is 64 bits.

The FIC consists of a total of 12 FIBs, and each FIB consists of a FIG data field composed of a plurality of fast information groups (FIGs) and one CRC field.

9 is an internal structure of a fast information block according to the present invention.

As shown in FIG. 9, the FIB includes a total of 30 bytes of FIB data fields and a CRC of 2 bytes. The FIB data field is composed of a plurality of FIGs and end markers indicating that there are no more pictures, and padding information which is a meaningless bit sequence inserted to match the transmission speed of data.

Each FIG is composed of FIG header and FIG data field, and FIG header is composed of 3 bits of FIG type field and 5 bits of length field.

FIG may include various information such as ensemble information, subchannel configuration information included in the ensemble, relationship information between a service and a service component, and definitions of packet mode service components.

In particular, since the FIB has a size of 256 bits, it is possible to quickly measure whether there is an error per block, and it is possible to calculate an error rate for many blocks per unit time.

10 is an internal block diagram of a digital broadcast receiving apparatus according to an embodiment of the present invention.

Although the block diagram shown in FIG. 10 is shown centering on a reception module and a function module for performing a handover control procedure of the digital broadcast reception device according to the present invention, a transmission module and other functional modules included in a general digital broadcast reception device It may be further included, for convenience it should be noted that the drawing does not show a functional module that is not directly related to the spirit disclosed in the present invention.

More specifically, FIG. 10 is a digital broadcast reception apparatus according to an embodiment of the present invention checks the CRC of the FIB included in the FIC to calculate a block error rate (BLER), the handover based on the calculated BLER Figure for explaining the procedure to perform the.

Referring to FIG. 10, the OFDM demodulator 1002 demodulates an OFDM modulated received signal introduced into an antenna and transmits the demodulated signal to the symbol separator 1004.

The symbol separator 1004 separates the FIC symbol and the MSC symbol included in the transmission frame and transmits the same to the transmission frame demultiplexer 1006.

The transmission frame demultiplexer 1006 classifies the received FIC symbol for each FIB and transfers the divided FIB to the FIB channel decoder 1008. Also, the transmission frame demultiplexer 1006 classifies the received MSC symbols for each CIF and transfers them to a de-interleaver 1018.

The FIB channel decoder 1108 performs an error correction function on the received FIB, and transfers the error corrected FIB to the block error checking unit 1010.

The block error checking unit 1010 checks whether the corresponding FIB has an error by using the CRC included in the FIB, and then checks the CRC verification result by the fast information block error rate calculating unit 1012-hereinafter, "FIB BLER calculating unit 1012. ) ". In addition, the block error checking unit 1010 stores the normally confirmed FIB in the FIB storage unit 1016, and discards the FIB in which an error occurs.

The FIB BLER calculator 1012 may determine whether to initiate a handover by comparing the quality reference parameter set by the handover controller 1014 with the FIB BLER calculated to date. In addition, the FIB BLER may be measured at regular intervals, the measurement result may be compared with a predetermined quality standard, and a predetermined event signal may be generated, and the generated event signal may be transmitted to the handover controller 1014.

In this case, the quality reference parameter may include a service quality threshold value, a maximum quality of service failure, a maximum quality of service satisfaction, and the like, which are reception quality criteria of the FIB.

In particular, the maximum number of times of poor service quality and the maximum number of times of satisfying the quality of service are a phenomenon in which unnecessary handover is attempted when the channel condition is temporarily poor and is quickly recovered. Accordingly, the channel is frequently changed and the viewing screen and the service are frequently interrupted. Is a parameter to prevent the error.

The event signal includes a first event signal indicating that the quality of service of the corresponding broadcast channel does not satisfy the quality standard, and a second event signal indicating that the FIB BLER measured for the corresponding broadcasting channel satisfies the quality standard. can do. In particular, the handover controller 1014 may regard the first event signal received first as a handover procedure start event.

The maximum quality of service failure is a value for limiting the number of times that the FIB BLER measured for a unit time exceeds the quality of service threshold value before selecting a target channel to perform handover. If so, the handover control unit 1014 selects a target channel to perform handover using the service relationship information stored in the FIB storage unit 1016.

Here, the handover control unit 1014 preferably selects a channel capable of supporting the continuity of a service currently being provided as a target channel.

The maximum number of quality satisfaction satisfies the limit of the number of times the FIC BLER measured for a certain time exceeds the quality of service threshold value when the FIB BLER of the selected target channel is smaller than the quality of service threshold value, i.e., the data reception quality is good. Is a value for

The handover control unit 1014 completes the handover by switching the channel to the target channel when the maximum service quality satisfaction number arrives.

The FIB BLER calculator 1012 transmits a predetermined corresponding event to the handover controller 1014 when the maximum number of times of failing the quality of service or the maximum number of times of satisfying the quality of service arrives.

For example, when the maximum quality of service is reached, a channel discovery event for controlling the handover target channel is transmitted, the maximum quality of service is reached, and the control is performed to perform a handover to the previously discovered channel completely. A handover initiation event may be sent.

According to an embodiment of the present invention, the quality reference parameter may be received through a broadcast channel, for example, an FIC, a return channel, or the like. The broadcast station may set or change a quality reference parameter, and the set or changed quality reference parameter may be a broadcast channel, for example, a fast information channel included in the broadcast channel. It may be broadcasted to the entire broadcasting network through a return channel or the like or selectively transmitted to a specific digital broadcast receiving apparatus.

The CIF delimited by the transmission frame demultiplexer 1006 is error corrected by the CIF channel decoder 1020 after convolutional deinterleaving by the deinterleaver 1018. The ensemble demultiplexer 1022 then identifies the service component combination-i.e. the ensemble-of the received transmission frame and transmits the demultiplexed data to a processing unit corresponding to the identified ensemble.

11 is a flowchart illustrating a handover procedure in a digital broadcast reception device according to an embodiment of the present invention.

Referring to FIG. 11, the digital broadcast reception apparatus sets quality reference parameters used in the handover algorithm according to the present invention (S1102). Here, the quality reference parameter may include a quality threshold value (Qos_T), a maximum service quality miss (Ns), a maximum service quality satisfaction number (Nc), and the like. For convenience of explanation, the variable for counting the current quality of service failure count is referred to as "N", and the variable for counting the current quality of service satisfaction count will be referred to as "T".

The digital broadcast reception apparatus measures the BLER of the FIB received from the broadcasting channel currently being accessed for a certain period (S1104), and compares whether the measured BLER value is larger than the set quality threshold QoS_T (S1106).

As a result of the comparison, when the measured FIB BLER is larger than Qos_T, that is, the quality of service of the currently connected broadcast channel is lower than the standard, the digital broadcast reception apparatus increases N by one (S1108), and the N value is larger than Ns. The comparison is the same (S1110).

As a result of the comparison, if the N value is greater than or equal to Ns, the digital broadcast reception apparatus initializes the BLER value (S1126) and performs step 1104 described above.

In step 1106, if the measured BLER value of the FIB is less than or equal to Qos_T, that is, if it is determined that the quality of service of the currently connected broadcast channel is good, the N value and the BLER value are initialized to 0 ( S1124), step 1104 is performed.

In step 1110, if N is greater than or equal to Ns, the digital broadcast reception apparatus may support service continuity for a broadcast channel currently being viewed or accessed by using relation information between ensemble, frequency, and service obtained in advance. A target channel is selected (S1112). At this time, the T value and the BLER value are initialized to zero.

When reception synchronization with the selected target channel is performed, the digital broadcast reception apparatus measures the FIB BLER of the selected target channel for a predetermined period (S1114), and compares whether the measured FIB BLER is smaller than the QoS_T value (S1116). If the FIB BLER of the selected target channel is smaller than the QoS_T value, it switches to the selected target channel and increases the T value by one (S1118).

Next, the digital broadcast reception apparatus compares whether the increased T value is greater than or equal to the Nc value (S1120).

As a result of the comparison, when the T value is smaller than the Nc value, after initializing the BLER to 0 (S1130), step 1114 is performed.

In step 1120, when the T value is greater than or equal to the Nc value, the digital broadcast reception device completes handover to the selected target channel. That is, step 1104 described above may be performed with respect to the target channel on which the handover is completed.

According to an embodiment of the present invention, when handover is required, priority may be given to a channel to be searched, and the FIB BLER of the corresponding target channel is measured according to the assigned priority, and the FIB BLER of the measured target channel is If the QoS_T is not satisfied, the FIB BLER for the next higher priority target channel may be measured.

That is, in step 1116, when the target channel FIB BLER is greater than or equal to QoS_T, the target channel having the next higher priority is selected, the T and the BLER are initialized to 0, and then step 1114 is performed.

According to another embodiment of the present invention, the quality of service reference value and the FIB BLER measurement period for the channel currently being accessed are set differently from the applied quality of service reference value and the FIB BLER measurement period for the target channel when performing handover. Can be.

In addition, it should be noted that different quality reference parameters may be applied to the handover algorithm depending on the type of service of the broadcast channel currently being accessed. That is, since the required QoS level may be different according to the type of service, the setting value of the quality reference parameter may be changed accordingly.

For example, the BLER required for the audio service may be set to 10%, and the BLER required for the video streaming service may be set to 1%.

Embodiments of the invention include a computer readable medium containing program instructions for performing various computer-implemented operations. The computer readable medium may include program instructions, local data files, local data structures, or the like, alone or in combination. The media may be those specially designed and constructed for the purposes of the present invention, or they may be of the kind well-known and available to those having skill in the computer software arts.

Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tape, optical recording media such as CD-ROMs, DVDs, magnetic-optical media such as floppy disks, and ROM, RAM, flash memory, and the like. Hardware devices specifically configured to store and execute the same program instructions are included.

The medium may be a transmission medium such as an optical or metal wire, a waveguide, or the like for transmitting a signal specifying a program command, a local data structure, or the like. Examples of program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like.

Preferred embodiments of the present invention described above are disclosed for purposes of illustration, and those skilled in the art will be able to make various modifications, changes, and additions within the spirit and scope of the present invention. Additions should be considered to be within the scope of the following claims.

1 is a structure of a digital multimedia broadcasting network according to an embodiment of the present invention.

2 is a frequency allocation example of a digital multimedia broadcasting service according to an embodiment of the present invention.

3 is a view for explaining a digital multimedia broadcasting frequency allocation method according to an embodiment of the present invention.

4 is a diagram for explaining inter-frequency handovers for the same ensemble according to one embodiment of the present invention;

5 is a diagram for explaining inter-frequency handovers for different ensembles according to one embodiment of the present invention;

FIG. 6 is a diagram for explaining a handover method between frequencies for a case where frequencies, ensembles, and services are different from each other according to an embodiment of the present invention; FIG.

7 is a digital broadcast frame structure according to the present invention.

8 is a detailed structure of a digital broadcast frame according to an embodiment of the present invention.

9 is an internal structure of a fast information block according to the present invention;

10 is an internal block diagram of a digital broadcast receiving apparatus according to an embodiment of the present invention.

11 is a flowchart illustrating a handover procedure in a digital broadcast receiving apparatus according to an embodiment of the present invention.

* Key Drawing

720: Fast Information Channel (FIC)

740: Fast Information Block (FIB)

730: Main Service Channel (MSC)

1008: FIB Channel Decoder

1010: block error check unit

1012: fast information channel block error rate calculator

1014: Handover Control

1016: fast information block storage unit

1180: Channel quality information storage unit for each road section

Claims (17)

A first step of measuring a first data reception quality of a fast information channel received from a currently connected first broadcast channel; A second step of determining whether handover is necessary by comparing the first data reception quality with a first preset quality criterion; A third step of selecting a target channel using previously obtained service relationship information when handover is necessary as a result of the determination; And A fourth step of determining whether to switch to the target channel by comparing a second data reception quality of the fast information channel received from the selected target channel with a preset second quality criterion; A method for performing handover in a digital broadcast reception device comprising a. The method of claim 1, And the fast information channel comprises at least one fast information block. The method of claim 2, And a fast information block included in the fast information channel is not time interleaved. The method of claim 2, And the first to second data reception quality is a block error rate (BLER) of the fast information block accumulated for a predetermined unit time. The method of claim 1, Between the second step and the third step, Counting the number of times that the first data reception quality does not satisfy the first quality criterion The method according to claim 1, further comprising determining that handover is necessary when the number of times of not satisfied exceeds a preset reference value. The method of claim 1, In the third step, the method for performing handover in the digital broadcast reception apparatus, characterized in that the channel that can support the service continuity of the first broadcast channel is selected first. The method of claim 1, The fourth step includes counting the number of times that the second data reception quality satisfies the second reference quality. The method of claim 1, further comprising completing the handover to the target channel when the number of times of satisfaction exceeds a preset reference value. A recording medium readable by an electronic device on which a program consisting of typed instructions for executing a handover method in a digital broadcast receiving device, A first step of measuring a first data reception quality of a fast information channel received from a currently connected first broadcast channel; A second step of determining whether handover is necessary by comparing the first data reception quality with a first preset quality criterion; A third step of selecting a target channel using previously obtained service relationship information when handover is necessary as a result of the determination; And A fourth step of determining whether to switch to the target channel by comparing a second data reception quality of the fast information channel received from the selected target channel with a preset second quality criterion; And a program for executing a method for performing a handover in a digital broadcast receiving apparatus. A block error checking unit checking an error of the corresponding fast information block by using an error checking code included in the channel decoded fast information block; A fast information block error rate calculation unit which receives an error check result from the block error check unit, calculates a fast information block error rate of a corresponding broadcast channel, and generates a predetermined event signal by comparing the calculated block error rate with a preset quality criterion. ; And A handover control unit which receives the event signal from the high speed information block error rate calculator and determines whether to initiate a handover procedure and whether to switch to a target channel. Digital broadcast receiving device comprising a. The method of claim 9, And a storage unit for retaining service relationship information corresponding to a currently connected broadcast channel, wherein the service relationship information includes an ensemble, a frequency, and a mutual mapping relationship for a service. The method of claim 10, If it is determined that the handover is necessary according to the event signal, the handover controller further includes means for selecting a channel capable of supporting the service continuation of the currently connected broadcast channel as a target channel with reference to the service relationship information. Digital broadcast receiving device characterized in that. The method of claim 9, And the quality criterion is received through any one of a return channel and a fast information channel. The method of claim 12, And the handover controller sets the received quality criterion to the fast transmission block error rate calculator using a predetermined control signal. The method of claim 9, The event signal is A first event signal indicating that a fast information block error rate of a corresponding broadcast channel per unit time does not satisfy the quality criterion; And A second event signal indicating that the fast information block error rate of the broadcast channel per unit time satisfies the quality criterion Digital broadcast receiving apparatus comprising at least one of. The method of claim 14, And the handover control unit recognizes that a handover procedure is initiated when the first event signal is first received. The method of claim 14, And the handover controller selects the target channel when the first event signal is continuously received a predetermined number of times. The method of claim 16, And the handover controller completes the handover to the selected target channel when the second event signal is continuously received a predetermined number of times.

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