1. Field of the Invention
The present invention relates generally to a broadcasting service, and in particular, to a broadcasting system and method for providing a broadcasting service in a weak electric field area.
2. Description of the Related Art
In general, digital broadcasting is a type of broadcasting service for providing high image quality, high sound quality, and a better service to users by replacing conventional analog broadcasting. Recently, in light of the development of digital broadcasting technology and mobile communication technology, users have become increasingly interested in a digital broadcasting service by which the users can watch a digital broadcasting program while in motion.
In the field of broadcasting service, there exists a digital multimedia broadcasting (DMB) service using a mobile communication terminal and a live streaming broadcasting service, which is a real-time multimedia service provided through a third generation (3G) network.
The DMB service is a broadcasting service that allows a user to watch various multi-channel DMB programs even while moving through the use of an omni-directional reception antenna equipped with a personal portable receiver or vehicle receiver. The DMB service is a service having active bi-directionality, personal portability, and mobility. This is achieved by subjugating a service of conventional broadcasting related to passive uni-directionality, a fixed area, and an individual media device, such as a radio or a TV; and providing a video/audio service and convergence of broadcasting and communication (e.g., Digital Audio Broadcasting (DAB)/DMB & 3G, Wideband Code Division Multiple Access (WCDMA) & portable Internet, Wireless Local Area Network (WLAN) & Wireless Internet Platform for Interoperability (WiFi), WiFi & portable Internet, and DAB/DMB & portable Internet) through a single DMB terminal. In addition, the DMB service provides a high quality multimedia service through various mobile terminals, such as cellular phones, laptop computers, Personal Digital Assistants (PDAs), and WiBro phones.
The DMB service is achieved by transmitting DMB data from the ground to a satellite and retransmitting the DMB data from the satellite back to the ground. DMB terminals receive the DMB data retransmitted by the satellite, i.e., directly from the satellite or receive the DMB data via a ground relay station. The ground relay station is a device for emitting DMB data received from a satellite by being installed at places where a satellite signal cannot reach, such as shadow areas due to tall buildings or underground areas.
When a DMB terminal receives DMB data via a ground relay station, the DMB terminal can receive the DMB data even if located in a place where a satellite signal cannot reach regardless of an orientation of a satellite or a signal transmitted directly from the satellite.
That is, in a case of Terrestrial DMB (T-DMB), a DMB terminal can receive DMB data while moving on the ground, but it may not receive the DMB data while located in underground areas. Relay stations (50˜70 Km) and gap fillers are required in order to solve a shadow area problem of T-DMB. In a case of Satellite DMB (S-DMB, the shadow area problem must also be solved, and in order to directly receive DMB data on the ground, power adjustment of S-band and installation of gap fillers for covering a radius 500 m are necessary. As such, until a solution has been provided to fully resolve the DMB shadow area problem, fringe areas and weak electric field areas will continue to exist, and therefore, cases where a DMB terminal temporarily cannot receive DMB data while moving will continue to occur, thereby limiting a seamless DMB service.
Thus, a case can occur where a user watching a DMB program using a DMB terminal temporarily cannot watch a portion of the DMB program due to a weak electric field area while moving outdoors. In this case, if the user wants to watch the missing portion of the DMB program, the user can watch a rebroadcasting program, or previously record the DMB program and watch the recorded DMB program at any time. In addition, the user can access a Video on Demand (VOD) server through the Internet or a mobile communication network, search for content corresponding to the DMB program, and watch the DMB program by downloading or streaming the found content. However, even if the user wants to watch the DMB program using the VOD server, the user can watch the DMB program only after the real-time DMB program is terminated.
As described above, a case where a user cannot watch a DMB program in a weak electric field area during a DMB service frequently occurs. According to the conventional art, there is no method of immediately watching the missing DMB program.