Reception apparatus, reception method, program, and reception system

1. A reception apparatus comprising:

circuitry configured to:

receive an orthogonal frequency division multiplexing (OFDM) signal formed by modulating common packet sequences and data packet sequences, said common packet sequences being made up of packets common to a plurality of streams, said data packet sequences being constituted by packets unique to each of said plurality of streams;

acquire decoding information for decoding original streams from said common packet sequences and said data packet sequences obtained by demodulating the received OFDM signal; and

search for a common packet sequence needed to decode the original streams from a designated data packet sequence on the basis of the acquired decoding information; and

a memory configured to store the decoding information about the acquired common packet sequences until the decoding information about said designated data packet sequence is acquired, wherein

when the decoding information about said designated data packet sequence is acquired, said circuitry searches the stored decoding information about said common packet sequences for the decoding information identified by the decoding information about the acquired data packet sequences.

2. The reception apparatus according to claim 1 , wherein, if the decoding information cannot be identified from the stored decoding information about said common packet sequences, then said circuitry is configured to search for the decoding information identified by the decoding information about the acquired data packet sequences out of that decoding information about said common packet sequences which is acquired following the acquisition of the decoding information about said designated data packet sequence.

3. The reception apparatus according to claim 2 , wherein

said memory includes as many as n registers, the number n satisfying a relationship of n=m where m represents a maximum number of units of the decoding information about said common packet sequences, and

if the decoding information about said common packet sequences cannot be identified from within a first frame targeted for the search, then said circuitry determines that said common packet sequences do not exist.

4. The reception apparatus according to claim 3 , wherein

there exist a predetermined number of units of the decoding information about said common packet sequences which are identified by the decoding information about said designated data packet sequence, and

said circuitry searches for said predetermined number of units of the decoding information about said common packet sequences which are identified by the decoding information about said designated data packet sequence.

5. The reception apparatus according to claim 2 , wherein

said memory includes as many as n registers, the number n satisfying a relationship of 1≦n≦m where m represents a maximum number of units of the decoding information about said common packet sequences, and

if the decoding information about said common packet sequences cannot be identified from within a first frame targeted for the search, then said circuitry searches through a second frame next to said first frame.

6. The reception apparatus according to claim 5 , wherein

there exist a predetermined number x of units of the decoding information about said common packet sequences which are identified by the decoding information about said designated data packet sequence, the number x satisfying a relationship of 1≦x≦n≦m, and

said circuitry searches for said predetermined number of units of the decoding information about said common packet sequences which are identified by the decoding information about said designated data packet sequence.

7. The reception apparatus according to claim 2 , wherein

there exist an indefinite number of units of the decoding information about said common packet sequences which are identified by the decoding information about said designated data packet sequence, and

said circuitry searches for said indefinite number of units of the decoding information about said common packet sequences which are identified by the decoding information about said designated data packet sequence.

8. The reception apparatus according to claim 1 , wherein

said decoding information includes at least a first and a second identifier, said first identifier identifying each packet sequence, said second identifier distinguishing the corresponding common packet sequence from said data packet sequences, and

said circuitry identifies the decoding information about the data packet sequence having the designated first identifier, before identifying the decoding information about the common packet sequence having said second identifier included in the decoding information about said designated data packet sequence.

9. The reception apparatus according to claim 1 , wherein the circuitry is further configured to decode the original streams from said common packet sequences and said data packet sequences based on a result of the search made by said circuitry.

10. The reception apparatus according to claim 1 , wherein said common packet sequences and said data packet sequences are constituted, respectively, by common physical pipe layers (Common PLPs) and by data physical pipe layers (Data PLPs) generated from a plurality of original streams according to a multiple physical layer pipe (M-PLP) method under DVB-T2.

11. A reception method for causing a reception apparatus to execute a procedure comprising:

receiving an orthogonal frequency division multiplexing (OFDM) signal formed by modulating common packet sequences and data packet sequences, said common packet sequences being made up of packets common to a plurality of streams, said data packet sequences being constituted by packets unique to each of said plurality of streams;

acquiring decoding information for decoding original streams from said common packet sequences and said data packet sequences obtained by demodulating the received OFDM signal;

searching for a common packet sequence needed to decode the original streams from a designated data packet sequence on the basis of the acquired decoding information;

storing the decoding information about the acquired common packet sequences until the decoding information about said designated data packet sequence is acquired; and

searching, when the decoding information about said designated data packet sequence is acquired, the stored decoding information about said common packet sequences for the decoding information identified by the decoding information about the acquired data packet sequences.

12. A non-transitory computer-readable medium comprising a program for causing a computer to execute a procedure comprising:

receiving an orthogonal frequency division multiplexing signal known as an OFDM signal formed by modulating common packet sequences and data packet sequences, said common packet sequences being made up of packets common to a plurality of streams, said data packet sequences being constituted by packets unique to each of said plurality of streams;

acquiring decoding information for decoding original streams from said common packet sequences and said data packet sequences obtained by demodulating the received OFDM signal;

searching for a common packet sequence needed to decode the original streams from a designated data packet sequence on the basis of the acquired decoding information;

storing the decoding information about the acquired common packet sequences until the decoding information about said designated data packet sequence is acquired; and

searching, when the decoding information about said designated data packet sequence is acquired, the stored decoding information about said common packet sequences for the decoding information identified by the decoding information about the acquired data packet sequences.

13. A reception system comprising:

communication interface circuitry configured to acquire via a transmission channel an orthogonal frequency division multiplexing (OFDM) signal formed by modulating common packet sequences and data packet sequences, said common packet sequences being made up of packets common to a plurality of streams, said data packet sequences being constituted by packets unique to each of said plurality of streams;

processing circuitry configured to perform a transmission channel decoding process including at least a packet sequence decoding process on said OFDM signal acquired via said transmission channel;

wherein said processing circuitry is configured to:

acquire decoding information for decoding original streams from said common packet sequences and said data packet sequences obtained by demodulating said OFDM signal received via said transmission channel, and

search for a common packet sequence needed to decode the original streams from a designated data packet sequence on the basis of the acquired decoding information; and

a memory configured to store the decoding information about the acquired common packet sequences until the decoding information about said designated data packet sequence is acquired, wherein

when the decoding information about said designated data packet sequence is acquired, said processing circuitry searches the stored decoding information about said common packet sequences for the decoding information identified by the decoding information about the acquired data packet sequences.

14. A reception system comprising:

transmission channel decoding circuitry configured to perform a transmission channel decoding process including at least a packet sequence decoding process on an orthogonal frequency division multiplexing (OFDM) signal acquired via a transmission channel and formed by modulating common packet sequences and data packet sequences, said common packet sequences being made up of packets common to a plurality of streams, said data packet sequences being constituted by packets unique to each of said plurality of streams;

information source decoding circuitry configured to perform an information source decoding process including at least a data decompression process on the OFDM signal having undergone said transmission channel decoding process;

wherein said transmission channel decoding circuitry is configured to:

acquire decoding information for decoding original streams from said common packet sequences and said data packet sequences obtained by demodulating said OFDM signal acquired via said transmission channel, and

search for a common packet sequence needed to decode the original streams from a designated data packet sequence on the basis of the acquired decoding information; and

a memory configured to store the decoding information about the acquired common packet sequences until the decoding information about said designated data packet sequence is acquired, wherein

when the decoding information about said designated data packet sequence is acquired, said transmission channel decoding circuitry searches the stored decoding information about said common packet sequences for the decoding information identified by the decoding information about the acquired data packet sequences.

15. A reception system comprising:

transmission channel decoding circuitry configured to perform a transmission channel decoding process including at least a packet sequence decoding process on an orthogonal frequency division multiplexing (OFDM) signal acquired via a transmission channel and formed by modulating common packet sequences and data packet sequences, said common packet sequences being made up of packets common to a plurality of streams, said data packet sequences being constituted by packets unique to each of said plurality of streams;

output circuitry configured to output an image or a sound based on the OFDM signal having undergone said transmission channel decoding process;

wherein said transmission channel decoding circuitry is configured to

acquire decoding information for decoding original streams from said common packet sequences and said data packet sequences obtained by demodulating said OFDM signal acquired via said transmission channel, and

search for a common packet sequence needed to decode the original streams from a designated data packet sequence on the basis of the acquired decoding information; and

a memory configured to store the decoding information about the acquired common packet sequences until the decoding information about said designated data packet sequence is acquired, wherein

when the decoding information about said designated data packet sequence is acquired, said transmission channel decoding circuitry searches the stored decoding information about said common packet sequences for the decoding information identified by the decoding information about the acquired data packet sequences.

16. A reception system comprising:

transmission channel decoding circuitry configured to perform a transmission channel decoding process including at least a packet sequence decoding process on an orthogonal frequency division multiplexing (OFDM) signal acquired via a transmission channel and formed by modulating common packet sequences and data packet sequences, said common packet sequences being made up of packets common to a plurality of streams, said data packet sequences being constituted by packets unique to each of said plurality of streams; and

recording circuitry configured to record the OFDM signal having undergone said transmission channel decoding process;

wherein said transmission channel decoding circuitry is configured to

acquire decoding information for decoding original streams from said common packet sequences and said data packet sequences obtained by demodulating said OFDM signal acquired via said transmission channel, and

search for a common packet sequence needed to decode the original streams from a designated data packet sequence on the basis of the acquired decoding information; and

a memory configured to store the decoding information about the acquired common packet sequences until the decoding information about said designated data packet sequence is acquired, wherein

when the decoding information about said designated data packet sequence is acquired, said transmission channel decoding circuitry searches the stored decoding information about said common packet sequences for the decoding information identified by the decoding information about the acquired data packet sequences.