BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to an apparatus for transmitting broadcast signals, an apparatus for receiving broadcast signals and methods for transmitting and receiving broadcast signals.

Discussion of the Related Art

As analog broadcast signal transmission comes to an end, various technologies for transmitting/receiving digital broadcast signals are being developed. A digital broadcast signal may include a larger amount of video/audio data than an analog broadcast signal and further include various types of additional data in addition to the video/audio data.

That is, a digital broadcast system can provide HD (high definition) images, multi-channel audio and various additional services. However, data transmission efficiency for transmission of large amounts of data, robustness of transmission/reception networks and network flexibility in consideration of mobile reception equipment need to be improved for digital broadcast.

SUMMARY OF THE INVENTION

To solve the technical problem above, a broadcast signal receiver according to an embodiment of the present invention comprises a synchronization & demodulation module configured to OFDM demodulate a received broadcast signal; a frame parsing module configured to parse a signal frame of the broadcast signal; a demapping & decoding module configured to convert PLP data of the broadcast signal to the bit domain and to FEC decode the converted PLP data; and an output processing module configured to receive the PLP data and to output a data stream, wherein the signal frame comprises a bootstrap, a preamble and at least one subframe, and wherein at least one subframe includes at least one subframe boundary symbol, the subframe boundary symbol being a first symbol or a last symbol of the at least one subframe and the subframe boundary symbol has a greater scattered pilot density than data symbols of the subframe.

In a broadcast signal receiver according to the present invention, the at least one subframe has a constant FFT size, constant GI length and a constant pilot pattern respectively, and the preamble comprises FFT size information, GI information and pilot pattern information for each subframe.

In a broadcast signal receiver according to the present invention, the scattered pilots of the subframe boundary symbol are determined based on scattered pilot density (Dx) of data symbols of the subframe, and the pilot density (Dx) indicates separation of pilot bearing carriers in frequency direction.

In a broadcast signal receiver according to the present invention, the preamble comprises subframe boundary symbol mode information and the subframe boundary symbol mode information indicates whether the first symbol of the subframe is a subframe boundary symbol or whether the last symbol of the subframe is the subframe boundary symbol.

In a broadcast signal receiver according to the present invention, at least one of a last symbol of an immediately preceding subframe or a first symbol of an immediately following subframe is the subframe boundary symbol for neighboring subframes when the signal frame comprises a plurality of subframes.

In a broadcast signal receiver according to the present invention, whether a first symbol of a first subframe immediately following the preamble is the subframe boundary symbol is determined based on whether a FFT size of the preamble and a FFT size of the first subframe are same to each other.

To solve the technical problem above, a method for receiving a broadcast signal according to an embodiment of the present invention comprises OFDM demodulating a received broadcast signal; parsing a signal frame of the broadcast signal; converting PLP data of the broadcast signal to the bit domain and FEC decoding the converted PLP data; and receiving the PLP data and outputting a data stream, wherein the signal frame comprises a bootstrap, a preamble and at least one subframe, and wherein at least one subframe includes at least one subframe boundary symbol, the subframe boundary symbol being a first symbol or a last symbol of the at least one subframe and the subframe boundary symbol has a greater scattered pilot density than data symbols of the subframe.

The present invention can process data according to service characteristics to control QoS (Quality of Services) for each service or service component, thereby providing various broadcast services.

The present invention can achieve transmission flexibility by transmitting various broadcast services through the same RF signal bandwidth.

The present invention can improve data transmission efficiency and increase robustness of transmission/reception of broadcast signals using a MIMO system.

According to the present invention, it is possible to provide broadcast signal transmission and reception methods and apparatus capable of receiving digital broadcast signals without error even with mobile reception equipment or in an indoor environment.

Further aspects and effects of the present invention will be described more detail with embodiments in belows.

