Patent Publication Number: US-2020305031-A1

Title: Broadcast signal reception method using network switching and apparatus for the same

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of Korean Patent Application No. 10-2019-0030896, filed Mar. 19, 2019, which is hereby incorporated by reference in its entirety into this application. 
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates generally to broadcast signal reception technology, and more particularly, to technology that can seamlessly provide a broadcasting service in a broadcasting environment in which a digital broadcast network and a broadband network are operable in conjunction with each other. 
     2. Description of the Related Art 
     With the development of recent broadcasting and communication technology, research into technology based on which two different types of networks are operated in conjunction with each other to provide a service has been conducted. 
     Because Advanced Television Systems Committee (ATSC) 3.0, which is the next-generation broadcasting standard, adopts an Internet Protocol (IP)-based broadcasting scheme, it is suitable for a service in which both a broadcast network and a broadband network are utilized. However, in order to provide a single service over two or more networks, there are many cases in which it is difficult to guarantee seamless communication when switching from one network to another. 
     PRIOR ART DOCUMENTS 
     Patent Documents 
     (Patent Document 1) 
     Korean Patent Application Publication No. 10-2015-0001914, Date of Publication: Jan. 7, 2015 (Title: Method and Apparatus for Supporting Handover of Contents in Mobile Broadcast and Broadband network”) 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a seamless broadcasting service in an environment in which a broadcast network and a broadband network are used. 
     Another object of the present invention is to seamlessly implement convergence, cooperation, handoff, etc., which utilize a broadband network in ATSC-3.0-based broadcasting. 
     In accordance with an aspect of the present invention to accomplish the above objects, there is provided a broadcast signal reception method using network switching, including determining, by a broadcast signal reception apparatus, a network-switching time point based on a network-switching condition that is set in consideration of at least one of a characteristics of a broadcast signal received over a broadcast network during a preset time period and a continuity of packets received over the broadcast network during the preset time period; and receiving, by the broadcast signal reception apparatus, the broadcast signal by performing network switching to a broadband network at the network-switching time point. 
     The characteristics of the broadcast signal may include a signal strength and a Signal-to-Noise Ratio (SNR), and the continuity of the packets includes information about whether audio/video packets are continuously received. 
     Determining the network-switching time point may be configured to determine that the network-switching condition is satisfied when a current state corresponds to at least one of a case where the signal strength becomes less than a preset reference signal strength, a case where the SNR becomes lower than a preset reference SNR, and a case where the audio/video packets are not continuously received. 
     Receiving the broadcast signal may include, when packet loss attributable to the broadcast network occurs, requesting a lost packet from a broadcasting server based on the broadband network, receiving the lost packet in a unicast manner, and then recovering the packet loss. 
     The broadcast signal reception method may further include, when the SNR becomes higher than the preset reference SNR while the signal strength is greater than the preset reference signal strength after the network switching, performing, by the broadcast signal reception apparatus, network re-switching to the broadcast network. 
     Performing the network re-switching may be configured to perform the network re-switching in additional consideration of the information about whether the audio/video packets are continuously received. 
     The broadcast signal reception method may further include performing time synchronization between the broadcast signal reception apparatus and at least one server and at least one transmission module for transmitting the broadcast signal and the packets. 
     In accordance with another aspect of the present invention to accomplish the above objects, there is provided a broadcast signal reception apparatus, including a processor for determining a network-switching time point based on a network-switching condition that is set in consideration of at least one of characteristics of a broadcast signal received over a broadcast network during a preset time period and a continuity of packets received over the broadcast network during the preset time period, performing network switching to a broadband network at the network-switching time point, and then receiving the broadcast signal, and a memory for storing the network-switching condition. 
     The characteristics of the broadcast signal may include a signal strength and a Signal-to-Noise Ratio (SNR), and the continuity of the packets includes information about whether audio/video packets are continuously received. 
     The processor may be configured to determine that the network-switching condition is satisfied when a current state corresponds to at least one of a case where the signal strength becomes less than a preset reference signal strength, a case where the SNR becomes lower than a preset reference SNR, and a case where the audio/video packets are not continuously received. 
     The processor may be configured to, when packet loss attributable to the broadcast network occurs, request a lost packet from a broadcasting server based on the broadband network, receive the lost packet in a unicast manner, and then recover the packet loss. 
     The processor may be configured to, when the SNR becomes higher than the preset reference SNR while the signal strength is greater than the preset reference signal strength after the network switching, perform network re-switching to the broadcast network. 
     The processor may be configured to perform the network re-switching in additional consideration of the information about whether the audio/video packets are continuously received. 
     The processor may be configured to perform time synchronization between the broadcast signal reception apparatus and at least one server and at least one transmission module for transmitting the broadcast signal and the packets. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a diagram illustrating a broadcast signal reception system using network switching according to an embodiment of the present invention; 
         FIG. 2  is an operation flowchart illustrating a broadcast signal reception method using network switching according to an embodiment of the present invention; 
         FIG. 3  is a diagram illustrating an example of switching between a broadcast network and a broadband network according to the present invention; 
         FIG. 4  is a diagram illustrating an example in which a lost packet is received over a broadband network according to the present invention; 
         FIG. 5  is a flow diagram illustrating in detail a network switching process according to an embodiment of the present invention; 
         FIG. 6  is a flow diagram illustrating in detail a network re-switching process according to an embodiment of the present invention; 
         FIG. 7  is a flow diagram illustrating in detail a lost packet acquisition process according to an embodiment of the present invention; 
         FIG. 8  is a block diagram illustrating a broadcast signal reception apparatus according to an embodiment of the present invention; and 
         FIG. 9  is a diagram illustrating a computer system according to an embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will be described in detail below with reference to the accompanying drawings. Repeated descriptions and descriptions of known functions and configurations which have been deemed to make the gist of the present invention unnecessarily obscure will be omitted below. The embodiments of the present invention are intended to fully describe the present invention to a person having ordinary knowledge in the art to which the present invention pertains. Accordingly, the shapes, sizes, etc. of components in the drawings may be exaggerated to make the description clearer. 
     In the present specification, it should be understood that terms such as “include” or “have” are merely intended to indicate that features, numbers, steps, operations, components, parts, or combinations thereof are present, and are not intended to exclude the possibility that one or more other features, numbers, steps, operations, components, parts, or combinations thereof will be present or added. 
     Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. 
       FIG. 1  is a diagram illustrating a broadcast signal reception system using network switching according to an embodiment of the present invention. 
     Referring to  FIG. 1 , cases to which the broadcast signal reception system using network switching according to an embodiment of the present invention is applied may be classified into the case  101  where a broadcast network is used and the case  102  where a broadband network is used through network switching. 
     First, a broadcast signal reception apparatus in the case  101  where the broadcast network is used determines a network-switching time point based on a network-switching condition that is set in consideration of at least one of the characteristics of a broadcast signal and the continuity of packets. Here, the broadcast signal characteristics may mean the characteristics of the broadcast signal received over the broadcast network during a preset time period, and the packet continuity may mean the continuity of packets received over the broadcast network during the preset time period. 
     Here, the broadcast signal characteristics may include signal strength and a Signal-to-Noise Ratio (SNR), and the packet continuity may include information about whether audio/video packets are continuously received. 
     In this case, when the current state corresponds to at least one of the case where signal strength becomes less than a preset reference (threshold) signal strength, the case where an SNR becomes lower than a preset reference SNR, and the case where audio/video packets are not continuously received, it may be determined that the network-switching condition is satisfied. 
     Thereafter, the broadcast signal reception apparatus in the case  101  where the broadcast network is used receives the broadcast signal by performing network switching to the broadband network at the network-switching time point. 
     Thereafter, the broadcast signal reception apparatus in the case  102  where the broadband network is used may request a lost packet from a broadcasting server based on the broadband network when packet loss attributable to the broadcast network occurs, may receive the lost packet in a unicast manner, and may then recover packet loss. 
     When the SNR of a broadcast signal, transmitted over the broadcast network, becomes higher than the preset reference SNR while the signal strength of the broadcast signal is greater than the preset reference signal strength after network switching to the broadband network, the broadcast signal reception apparatus may perform network re-switching to the broadcast network. 
     Here, the network re-switching may also be performed in additional consideration of information about whether audio/video packets are continuously received. 
     Here, both in the case  101  where the broadcast network is used and in the case  102  where the broadband network is used through network switching, time synchronization may be performed between the broadcast signal reception apparatus and at least one server and at least one transmission module for transmitting the broadcast signal and the packets. 
     In this way, network switching is performed by monitoring, in real time, physical-layer parameters and Audio/Video (A/V) signal packets, and thus a seamless broadcasting service may be provided. 
       FIG. 2  is an operation flowchart illustrating a broadcast signal reception method using network switching according to an embodiment of the present invention. 
     Referring to  FIG. 2 , in the broadcast signal reception method using network switching according to an embodiment of the present invention, a broadcast signal reception apparatus determines a network-switching time point based on a network-switching condition that is set in consideration of at least one of the characteristics of a broadcast signal received over the broadcast network during a preset time period and the continuity of packets received over the broadcast network during the preset time period at step S 210 . 
     For example, referring to  FIG. 3 , a broadcast network service based on a broadcast network transmission apparatus  310  that utilizes a high-power/high-tower structure may transmit a broadcast signal to broadcast network coverage  311 , but it may be difficult to receive a broadcast signal in an indoor area. Therefore, in the indoor area, as illustrated in  FIG. 3 , the broadcast signal may be transmitted to a broadcast signal reception apparatus  302  through a Wi-Fi network using a broadband network transmission apparatus  330 , such as a home gateway. Also, even in an outdoor area, there may occur the situation in which a user who carries a broadcast signal reception apparatus  301  moves out of the area of the broadcast network coverage  311 . Thus, in this case, the corresponding service may be provided using a broadband network transmission apparatus  320  corresponding to a mobile base station, such as for 4G/5G communication. 
     In this way, when a single service is to be provided over multiple networks (e.g. networks for broadcasting, mobile communication, Wi-Fi, etc.), there is a need to perform seamless network switching that enables a service to be provided seamlessly from the aspect of a viewer who watches broadcasting through a broadcast signal reception apparatus, and thus the present invention intends to propose a method for such a seamless service. 
     Here, the broadcast signal characteristics may include signal strength and a Signal-to-Noise Ratio (SNR), and the packet continuity may include information about whether audio/video packets are continuously received. 
     That is, the broadcast signal reception apparatus may predict the time point at which a broadcast signal will be actually interrupted by monitoring, in real time, physical-layer parameters, such as the signal strength or SNR of the broadcast signal that is transferred over the broadcast network, or by monitoring, in real time, whether audio/video packets are continuously received. 
     In this case, when the current state corresponds to at least one of the case where signal strength becomes less than a preset reference (threshold) signal strength, the case where the SNR becomes lower than a preset reference SNR, and the case where audio/video packets are not continuously received, it may be determined that the network-switching condition is satisfied. 
     At this time, the case where the signal strength becomes less than the preset reference (threshold) signal strength may include the case where the signal strength is less than or equal to the preset reference signal strength, and the case where the SNR becomes lower than the preset reference SNR may include the case where the SNR is lower than or equal to the preset reference SNR. 
     If it is determined at step S 215  that the current time point is the network-switching time point, the broadcast signal reception apparatus receives the broadcast signal by performing network switching to the broadband network at step S 220 . 
     For example, when only the signal strength and SNR of the broadcast signal received over the broadcast network are taken into consideration, network switching from the broadcast network to the broadband network may be performed based on the following [Logic 1]: 
       If (SS≤SS_thr) OR (SNR≤SNR_thr) for Time_Period  [Logic 1]
 
     Switch to Broadband 
     Here, SS denotes signal strength, SS_thr denotes the threshold value of signal strength, SNR may denote a Signal-to-Noise Ratio (SNR), SNR_thr denotes the threshold value of SNR, and Time_Period denotes a time period. 
     Here, each of SS_thr, SNR_thr, and Time_Period may be set and changed through the broadcast signal reception apparatus. 
     For example, in the case of a system in which an ATSC 3.0 broadcasting mode is operated at SNR=5 dB, the broadcast signal reception apparatus inputs the value of SNR_thr as 6 dB, thus enabling seamless network switching from the broadcast network to the broadband network before the broadcast signal is actually interrupted. Similarly, the value of SS_thr may be set to a value higher than the minimum signal strength operating in the broadcast signal reception apparatus depending on a physical-layer mode, thus enabling seamless network switching from the broadcast network to the broadband network. 
     Here, a Time_Period condition is input, so that, when the corresponding condition is satisfied during a specific time period in which a broadcast signal is input, network switching to the broadband network may be performed. 
     In another example, when information about whether audio/video packets are continuously received, together with the signal strength and SNR of the broadcast signal received over the broadcast network, is additionally taken into consideration, network switching from the broadcast network to the broadband network may be performed based on the following [Logic 2]: 
       If (SS≤SS_thr) OR (SNR≤SNR_thr) OR (A/V Out) for Time_Period  [Logic 2]
 
     Switch to Broadband 
     Here, A/V Out may denote the case where the loss of audio/video packets is detected in the buffer of the broadcast signal reception apparatus, that is, the case where audio/video packets are not continuously received over the broadcast network. 
     Here, when packet loss attributable to the broadcast network occurs, a lost packet may be requested from the broadcasting server based on the broadband network, and may be received in a unicast manner, and thus packet loss may be recovered. 
     For example, in the coverage edge and shadow area of an ATSC 3.0 broadcast network and a mobile environment, interruption of broadcast signals may occur, and at this time, IP packet loss may occur. Therefore, as illustrated in  FIG. 4 , in the present invention, a broadcast signal reception apparatus  430  may request a lost IP packet attributable to the broadcast network from a broadcasting server  410  through a broadband network transmission apparatus  420 , and only the lost packet may be transmitted over the broadband network in a unicast manner, thus providing a seamless service. 
     Such a broadcast network/broadband network cooperation service may also be provided at an A/V frame level, as well as at a Multi-mode Mobile Terminal/Internet Protocol (MMT/IP) (or a router/IP) level. That is, when an A/V frame sequence lost due to the broadcast network is found and requested based on the broadband network, the broadcasting server  410  may provide an IP packet including the requested A/V frame sequence in a unicast manner over the broadband network. 
     Here, if it is determined at step S 215  that the current time point is not a network-switching time point, monitoring may be continuously performed, and thus whether the current time point is a network-switching time point may be determined. 
     Further, although not illustrated in  FIG. 2 , in the broadcast signal reception method using network switching according to an embodiment of the present invention, when the SNR of a broadcast signal becomes higher than the preset reference SNR while the signal strength of the broadcast signal is greater than the preset reference signal strength after network switching, the broadcast signal reception apparatus may perform network re-switching to the broadcast network. That is, when the quality of a signal transferred over the broadcast network is improved, network re-switching from the broadband network to the broadcast network may be performed. 
     At this time, the case where the signal strength becomes greater than the preset reference signal strength may include the case where the signal strength is equal to or greater than the preset reference signal strength, and the case where the SNR becomes higher than the preset reference SNR may include the case where the SNR is equal to or higher than the preset reference SNR. 
     For example, network re-switching to the broadcast network may be performed based on the following [Logic 3]: 
       If (SS&gt;SS_thr) AND (SNR&gt;SNR_thr) for Time_Period  [Logic 3]
 
     Switch to Broadcast 
     Here, similar to network switching, network re-switching may be seamlessly performed by monitoring the SNR and signal strength in real time. 
     Here, network re-switching may also be performed in additional consideration of information about whether audio/video packets are continuously received. 
     For example, network re-switching may be performed in consideration of information about whether audio/video packets are continuously received based on the following [Logic 4]: 
       If (SS&gt;SS_thr) AND (SNR&gt;SNR_thr) AND (A/V On) for Time_Period  [Logic 4]
 
     Switch to Broadcast 
     Here, A/V On may denote the case where it is detected, by the buffer of the broadcast signal reception apparatus, that audio/video packets are continuously received over the broadcast network. 
     Further, although not illustrated in  FIG. 2 , in the broadcast signal reception method using network switching according to an embodiment of the present invention, time synchronization may be performed between the broadcast signal reception apparatus and at least one server and at least one transmission module for transmitting the broadcast signal and the packets. 
     For example, when all of an A/V player, a signaling server, an A/V encoder, an IP multiplexer, a broadcast gateway, and a transmitter that are used in a studio and a television tower may be operated in a time-synchronized manner, time synchronization may be performed using a Network Time Protocol (NTP), a Precision Time Protocol (PTP), a Global Positioning System (GPS), or the like. In this case, the broadcast signal reception apparatus may also perform time synchronization using a GPS or a broadband network protocol (e.g. NTP, PTP, or the like), and may search the broadcast network or the broadband network for a required IP packet or an A/V frame through a Presentation Time Stamp (PTS) set by the studio. This configuration may also be used for seamless service switching between the broadcast network and the broadband network. 
     Further, although not illustrated in  FIG. 2 , the broadcast signal reception method using network switching according to an embodiment of the present invention may store various types of information, generated during the broadcast signal reception process according to an embodiment of the present invention, in a separate storage module, as described above. 
     By means of the broadcast signal reception method using network switching according to the embodiment of the present invention, a seamless broadcasting service may be provided in an environment in which a broadcast network and a broadband network are used. 
     Also, convergence, cooperation, handoff, etc., which utilize a broadband network, may be seamlessly implemented in ATSC 3.0-based broadcasting. 
       FIG. 5  is a flow diagram illustrating in detail a network switching process according to an embodiment of the present invention. 
     Referring to  FIG. 5 , first, a broadcasting server  540  may configure an environment in which a broadcast signal may be provided to a broadcast signal reception apparatus  510  over a broadcast network  520  or a broadband network  530  by transmitting the broadcast signal and a packet to each of the broadcast network  520  and the broadband network  530  at step S 502 . 
     Next, the broadcast signal reception apparatus  510  may receive the broadcast signal and the packet over the broadcast network  520  at step S 504 . 
     Thereafter, the broadcast signal reception apparatus  510  may determine a network-switching time point based on a preset network-switching condition at step S 506 . 
     In this case, the network-switching condition may be set in consideration of at least one of the characteristics of a broadcast signal received during a preset time period and the continuity of packets received during the preset time period. 
     Thereafter, if it is determined at step S 508  that the current time point is the network-switching time point, the broadcast signal reception apparatus  510  may perform network switching at step S 510 , and may then receive a broadcast signal and a packet over the broadband network  530  at step S 512 . 
       FIG. 6  is a flow diagram illustrating in detail a network re-switching process according to an embodiment of the present invention. 
     Referring to  FIG. 6 , first, a broadcasting server  640  may configure an environment in which a broadcast signal may be provided to a broadcast signal reception apparatus  610  over a broadcast network  620  or a broadband network  630  by transmitting the broadcast signal and a packet to each of the broadcast network  620  and the broadband network  630  at step S 602 . 
     In this case, as illustrated in  FIG. 6 , if it is assumed that the broadcast signal reception apparatus  610  has already been receiving the broadcast signal and the packet from the broadband network  630  through network switching at step S 604 , the broadcast signal reception apparatus  610  may receive the broadcast signal and the packet from the broadcast network  620  so as to determine network re-switching in the future at step S 606 . 
     Thereafter, the broadcast signal reception apparatus  610  may determine a network re-switching time point based on the broadcast signal and the packet received from the broadcast network  620  at step S 608 . 
     Here, when the SNR of the broadcast signal received from the broadcast network  620  becomes higher than a preset reference SNR while the signal strength of the broadcast signal is greater than a preset reference signal strength, it may be determined that the current time point is a network re-switching time point. Also, the network re-switching time point may also be determined in additional consideration of information about whether audio/video packets are continuously received from the broadcast network  620 . 
     Thereafter, if it is determined at step S 610  that the current time point is the network re-switching time point, the broadcast signal reception apparatus  610  performs network re-switching at step S 612 , and may then receive again a broadcast signal and a packet over the broadcast network  620  at step S 614 . 
       FIG. 7  is a flow diagram illustrating in detail a lost packet acquisition process according to an embodiment of the present invention. 
     Referring to  FIG. 7 , first, a broadcasting server  740  may configure an environment in which a broadcast signal may be provided to a broadcast signal reception apparatus  710  over a broadcast network  720  or a broadband network  730  by transmitting the broadcast signal and a packet to each of the broadcast network  720  and the broadband network  730  at step S 702 . 
     In this case, as illustrated in  FIG. 7 , if it is assumed that the broadcast signal reception apparatus  710  has already been receiving the broadcast signal and the packet from the broadband network  730  through network switching at step S 704 , whether packet loss has occurred through the broadcast network  720  during network switching or before network switching may be determined at step S 706 . 
     If it is determined at step S 706  that packet loss has occurred, the broadcast signal reception apparatus  710  may request a lost packet from the broadband network  730  at step S 708 . 
     Thereafter, the broadcast signal reception apparatus  710  may recover the packet loss by receiving the lost packet in a unicast manner from the broadband network  730  at step S 710 . 
       FIG. 8  is a block diagram illustrating a broadcast signal reception apparatus according to an embodiment of the present invention. 
     Referring to  FIG. 8 , the broadcast signal reception apparatus according to an embodiment of the present invention may include a communication unit  810 , a processor  820 , and memory  830 . 
     The communication unit  810  may function to transmit/receive information required in order to receive a broadcast signal over a broadband network such as a typical network. In particular, the communication unit  810  according to an embodiment of the present invention may send a message for requesting a lost packet from a broadcasting server when packet loss occurs, and may receive the lost packet in response to the request. 
     The processor  820  determines a network-switching time point based on a network-switching condition that is set in consideration of at least one of the characteristics of a broadcast signal received over the broadcast network during a preset time period and the continuity of packets received over the broadcast network during a preset time period. 
     For example, referring to  FIG. 3 , a broadcast network service based on a broadcast network transmission apparatus  310  that utilizes a high-power/high-tower structure may transmit a broadcast signal to broadcast network coverage  311 , but it may be difficult to receive a broadcast signal in an indoor area. Therefore, in the indoor area, as illustrated in  FIG. 3 , the broadcast signal may be transmitted to a broadcast signal reception apparatus  302  through a Wi-Fi network using a broadband network transmission apparatus  330 , such as a home gateway. Also, even in an outdoor area, there may occur the situation in which a user who carries a broadcast signal reception apparatus  301  moves out of the area of the broadcast network coverage  311 . Thus, in this case, the corresponding service may be provided using a broadband network transmission apparatus  320  corresponding to a mobile base station, such as for 4G/5G communication. 
     In this way, when a single service is to be provided over multiple networks (e.g. networks for broadcasting, mobile communication, Wi-Fi, etc.), there is a need to perform seamless network switching that enables a service to be provided seamlessly from the aspect of a viewer who watches broadcasting through a broadcast signal reception apparatus, and thus the present invention intends to propose a method for such a seamless service. 
     Here, the broadcast signal characteristics may include signal strength and a Signal-to-Noise Ratio (SNR), and the packet continuity may include information about whether audio/video packets are continuously received. 
     That is, the broadcast signal reception apparatus may predict the time point at which a broadcast signal will be actually interrupted by monitoring, in real time, physical-layer parameters, such as the signal strength or SNR of the broadcast signal that is transferred over the broadcast network, or by monitoring, in real time, whether audio/video packets are continuously received. 
     In this case, when the current state corresponds to at least one of the case where signal strength becomes less than a preset reference (threshold) signal strength, the case where the SNR becomes lower than a preset reference (threshold) SNR, and the case where audio/video packets are not continuously received, it may be determined that the network-switching condition is satisfied. 
     At this time, the case where the signal strength becomes less than the preset reference signal strength may include the case where the signal strength is less than or equal to the preset reference signal strength, and the case where the SNR becomes lower than the preset reference SNR may include the case where the SNR is lower than or equal to the preset reference SNR. 
     Further, the processor  820  receives the broadcast signal by performing network switching to the broadband network at the network-switching time point. 
     For example, when only the signal strength and SNR of the broadcast signal received over the broadcast network are taken into consideration, network switching from the broadcast network to the broadband network may be performed based on the following [Logic 1]: 
       If (SS≤SS_thr) OR (SNR≤SNR_thr) for Time_Period  [Logic 1]
 
     Switch to Broadband 
     Here, SS denotes signal strength, SS_thr denotes the threshold value of signal strength, SNR may denote a Signal-to-Noise Ratio (SNR), SNR_thr denotes the threshold value of SNR, and Time_Period denotes a time period. 
     Here, each of SS_thr, SNR_thr, and Time_Period may be set and changed through the broadcast signal reception apparatus. 
     For example, in the case of a system in which an ATSC 3.0 broadcasting mode is operated at SNR=5 dB, the broadcast signal reception apparatus inputs the value of SNR_thr as 6 dB, thus enabling seamless network switching from the broadcast network to the broadband network before the broadcast signal is actually interrupted. Similarly, the value of SS_thr may be set to a value higher than the minimum signal strength operating in the broadcast signal reception apparatus depending on a physical-layer mode, thus enabling seamless network switching from the broadcast network to the broadband network. 
     Here, a Time_Period condition is input, so that, when the corresponding condition is satisfied during a specific time period in which a broadcast signal is input, network switching to the broadband network may be performed. 
     In another example, when information about whether audio/video packets are continuously received, together with the signal strength and SNR of the broadcast signal received over the broadcast network, is additionally taken into consideration, network switching from the broadcast network to the broadband network may be performed based on the following [Logic 2]: 
       If (SS≤SS_thr) OR (SNR≤SNR_thr) OR (A/V Out) for Time_Period  [Logic 2]
 
     Switch to Broadband 
     Here, A/V Out may denote the case where the loss of audio/video packets is detected in the buffer of the broadcast signal reception apparatus, that is, the case where audio/video packets are not continuously received over the broadcast network. 
     Here, when packet loss attributable to the broadcast network occurs, a lost packet may be requested from the broadcasting server based on the broadband network, and may be received in a unicast manner, and thus packet loss may be recovered. 
     For example, in the coverage edge and shadow area of an ATSC 3.0 broadcast network and a mobile environment, interruption of broadcast signals may occur, and at this time, IP packet loss may occur. Therefore, as illustrated in  FIG. 4 , in the present invention, a broadcast signal reception apparatus  430  may request a lost IP packet attributable to the broadcast network from a broadcasting server  410  through a broadband network transmission apparatus  420 , and only the lost packet may be transmitted over the broadband network in a unicast manner, thus providing a seamless service. 
     Such a broadcast network/broadband network cooperation service may also be provided at an A/V frame level, as well as at a Multi-mode Mobile Terminal/Internet Protocol (MMT/IP) (or a router/IP) level. That is, when an A/V frame sequence lost due to the broadcast network is found and requested based on the broadband network, the broadcasting server  410  may provide an IP packet including the requested A/V frame sequence in a unicast manner over the broadband network. 
     Further, when the SNR of a broadcast signal becomes higher than the preset reference SNR while the signal strength of the broadcast signal is greater than the preset reference signal strength after network switching, the processor  820  may perform network re-switching to the broadcast network. That is, when the quality of a signal transferred over the broadcast network is improved, network re-switching from the broadband network to the broadcast network may be performed. 
     At this time, the case where the signal strength becomes greater than the preset reference signal strength may include the case where the signal strength is equal to or greater than the preset reference signal strength, and the case where the SNR becomes higher than the preset reference SNR may include the case where the SNR is equal to or higher than the preset reference SNR. 
     For example, network re-switching to the broadcast network may be performed based on the following [Logic 3]: 
       If (SS&gt;SS_thr) AND (SNR&gt;SNR_thr) for Time_Period  [Logic 3]
 
     Switch to Broadcast 
     Here, similar to network switching, network re-switching may be seamlessly performed by monitoring the SNR and signal strength in real time. 
     Here, network re-switching may also be performed in additional consideration of information about whether audio/video packets are continuously received. 
     For example, network re-switching may be performed in consideration of information about whether audio/video packets are continuously received based on the following [Logic 4]: 
       If (SS&gt;SS_thr) AND (SNR&gt;SNR_thr) AND (A/V On) for Time_Period  [Logic 4]
 
     Switch to Broadcast 
     Here, A/V On may denote the case where it is detected, by the buffer of the broadcast signal reception apparatus, that audio/video packets are continuously received over the broadcast network. 
     Further, the processor  820  may perform time synchronization between the broadcast signal reception apparatus and at least one server and at least one transmission module for transmitting the broadcast signal and the packets. 
     For example, when all of an A/V player, a signaling server, an A/V encoder, an IP multiplexer, a broadcast gateway, and a transmitter that are used in a studio and a television tower may be operated in a time-synchronized manner, time synchronization may be performed using a Network Time Protocol (NTP), a Precision Time Protocol (PTP), a Global Positioning System (GPS), or the like. In this case, the broadcast signal reception apparatus may also perform time synchronization using a GPS or a broadband network protocol (e.g. NTP, PTP, or the like), and may search the broadcast network or the broadband network for a required IP packet or an A/V frame through a Presentation Time Stamp (PTS) set by the studio. This configuration may also be used for seamless service switching between the broadcast network and the broadband network. 
     The memory  830  stores the network-switching condition. 
     Furthermore, the memory  830  may store various types of information generated during the broadcast signal reception process according to the embodiment of the present invention, as described above. 
     In accordance with an embodiment, the memory  830  may be configured independently of the broadcast signal reception apparatus, thus supporting a function for receiving broadcast signals. Here, the memory  830  may function as a separate large-capacity (mass) storage, and may include a control function for performing operations. 
     Meanwhile, the broadcast signal reception apparatus may be equipped with memory, and may internally store information in the apparatus. In an embodiment, the memory may be a computer-readable storage medium. In an embodiment, the memory may be a volatile memory unit, and in another embodiment, the memory may be a nonvolatile memory unit. In an embodiment, a storage device may be a computer-readable storage medium. In various different embodiments, the storage device may include, for example, a hard disk device, an optical disk device or any other mass storage device. 
     By utilizing the broadcast signal reception apparatus according to the embodiment of the present invention, a seamless broadcasting service may be provided in an environment in which a broadcast network and a broadband network are used. 
     Also, convergence, cooperation, handoff, etc., which utilize a broadband network, may be seamlessly implemented in ATSC 3.0-based broadcasting. 
       FIG. 9  is a diagram illustrating a computer system according to an embodiment of the present invention. 
     Referring to  FIG. 9 , the embodiment of the present invention may be implemented in a computer system such as a computer-readable storage medium. As illustrated in  FIG. 9 , a computer system  900  may include one or more processors  910 , memory  930 , a user interface input device  940 , a user interface output device  950 , and storage  960 , which communicate with each other through a bus  920 . The computer system  900  may further include a network interface  970  connected to a network  980 . Each processor  910  may be a Central Processing Unit (CPU) or a semiconductor device for executing processing instructions stored in the memory  930  or the storage  960 . Each of the memory  930  and the storage  960  may be any of various types of volatile or nonvolatile storage media. For example, the memory  930  may include Read-Only Memory (ROM)  931  or Random Access Memory (RAM)  932 . 
     Therefore, the embodiment of the present invention may be implemented as a non-transitory computer-readable medium in which a computer-implemented method is recorded or in which computer-executable instructions are recorded. When the computer-executable instructions are executed by the processor, the instructions may perform the method according to at least one aspect of the present invention. 
     In accordance with the present invention, there can be provided a seamless broadcasting service in an environment in which a broadcast network and a broadband network are used. 
     Also, the present invention may seamlessly implement convergence, cooperation, handoff, etc., which utilize a broadband network, in ATSC 3.0-based broadcasting. 
     As described above, in the broadcast signal reception method and the apparatus for the method according to the present invention, the configurations and schemes in the above-described embodiments are not limitedly applied, and some or all of the above embodiments can be selectively combined and configured such that various modifications are possible.