Methods and apparatus for synchronization of data frames

1. A method comprising:

assigning a first bit sequence of a first length to a first group of signaling bits;

generating a first scrambling sequence and scrambling the first bit sequence with the first scrambling sequence;

assigning a first orthogonal frequency division multiplexing symbol to the first scrambled bit sequence; and

transmitting the first orthogonal frequency division multiplexing symbol as synchronization symbol of a data frame, wherein the first group of signaling bits indicates whether a next symbol comprises a second orthogonal frequency division multiplexing symbol as an additional synchronization symbol, wherein the second orthogonal frequency division multiplexing symbol comprises a second bit sequence scrambled by a second scrambling sequence and assigned to a second group of signaling bits, wherein the first and second bit sequences have the same length, wherein the first scrambling sequence is generated by a pseudo random binary sequence generator using a first initialization value, and wherein the second scrambling sequence is generated by the pseudorandom binary sequence generator using a second initialization value.

2. The method according to claim 1 , wherein the second group of signaling bits comprises information different from the first group of signaling bits.

3. The method according to claim 1 , wherein the data frame is a data frame of a digital video broadcast.

4. A method comprising:

receiving an orthogonal frequency division multiplexing signal comprising a first orthogonal frequency division multiplexing symbol;

synchronizing a data frame based at least in part on the first orthogonal frequency division multiplexing symbol, wherein the first orthogonal frequency division multiplexing symbol corresponds to a first scrambled bit sequence;

descrambling the first scrambled bit sequence with a first scrambling sequence; and

decoding a first group of signaling bits from the first descrambled bit sequence, wherein the first group of signaling bits indicates whether a next symbol comprises a second orthogonal frequency division multiplexing symbol as an additional synchronization symbol

determining from the first group of signaling bits whether the second orthogonal frequency division multiplexing synchronization symbol is present, and

in response to determining that the second orthogonal frequency division multiplexing synchronization symbol is present:

receiving the second orthogonal frequency division multiplexing synchronization symbol corresponding to a second scrambled bit sequence;

descrambling the second scrambled bit sequence with a second scrambling sequence; and

decoding a second group of signaling bits from the second descrambled bit sequence, wherein the first and second bit sequences have the same length, wherein the first scrambling sequence is generated by a pseudorandom binary sequence generator using a first initialization value, and wherein the second scrambling sequence is generated by the pseudorandom binary sequence generator using a second initialization value.

5. The method according to claim 4 , wherein the second group of signaling bits comprises information different from the first group of signaling bits.

6. An apparatus, comprising:

at least one hardware processor; and

at least one memory including computer program code,

the at least one memory and the computer program code configured to, with the at least one hardware processor, cause the apparatus to perform at least the following:

assign a first bit sequence of a first length to a first group of signaling bits;

generate a first scrambling sequence and scramble the first bit sequence with the first scrambling sequence;

assign a first orthogonal frequency division multiplexing symbol to the first scrambled bit sequence; and

transmit the first orthogonal frequency division multiplexing symbol as synchronization symbol of a data frame, wherein the first group of signaling bits indicates whether a next symbol comprises a second orthogonal frequency division multiplexing symbol as an additional synchronization symbol, wherein the second orthogonal frequency division multiplexing symbol comprises a second bit sequence scrambled by a second scrambling sequence and assigned to a second group of signaling bits, wherein the first and second bit sequences have the same length, wherein the first scrambling sequence is generated by a pseudo random binary sequence generator using a first initialization value, and wherein the second scrambling sequence is generated by the pseudorandom binary sequence generator using a second initialization value.

7. A non-transitory computer program product comprising a computer-readable medium bearing computer program code embodied therein for use with a computer, the computer program code comprising:

code for assigning a first bit sequence of a first length to a first group of signaling bits;

code for generating a first scrambling sequence and code for scrambling the first bit sequence with the first scrambling sequence;

code for assigning a first orthogonal frequency division multiplexing symbol to the first scrambled bit sequence; and

code for transmitting the first orthogonal frequency division multiplexing symbols as synchronization symbol of a data frame, wherein the first group of signaling bits indicates whether a next symbol comprises a second orthogonal frequency division multiplexing symbol as an additional synchronization symbol, wherein the second orthogonal frequency division multiplexing symbol comprises a second bit sequence scrambled by a second scrambling sequence and assigned to a second group of signaling bits, wherein the first and second bit sequences have the same length, wherein the first scrambling sequence is generated by a pseudo random binary sequence generator using a first initialization value, and wherein the second scrambling sequence is generated by the pseudorandom binary sequence generator using a second initialization value.

8. A non-transitory computer-readable medium encoded with instructions that, when executed by a computer, perform:

assigning a first bit sequence of a first length to a first group of signaling bits;

generating a first scrambling sequence and scrambling the first bit sequence with the first scrambling sequence;

assigning a first orthogonal frequency division multiplexing symbol to the first scrambled bit sequence; and

transmitting the first and second orthogonal frequency-division multiplexing symbols as synchronization symbols of a data frame, wherein the first group of signaling bits indicates whether a next symbol comprises a second orthogonal frequency division multiplexing symbol as an additional synchronization symbol, wherein the second orthogonal frequency division multiplexing symbol comprises a second bit sequence scrambled by a second scrambling sequence and assigned to a second group of signaling bits, wherein the first and second bit sequences have the same length, wherein the first scrambling sequence is generated by a pseudo random binary sequence generator using a first initialization value, and wherein the second scrambling sequence is generated by the pseudorandom binary sequence generator using a second initialization value.

9. An apparatus, comprising:

at least one hardware processor; and

at least one memory including computer program code,

the at least one memory and the computer program code configured to, with the at least one hardware processor, cause the apparatus to perform at least the following:

receive an orthogonal frequency-division multiplexing signal comprising a first orthogonal frequency-division multiplexing symbol;

synchronize a data frame based at least in part on the first orthogonal frequency division multiplexing symbol, wherein the first orthogonal frequency division multiplexing symbol corresponds to a first scrambled bit sequence;

descramble the first scrambled bit sequence with a first scrambling sequence; and

decode a first group of signaling bits from the first descrambled bit sequence, wherein the first group of signaling bits indicates whether a next symbol comprises a second orthogonal frequency division multiplexing symbol as an additional synchronization symbol

determine from the first group of signaling bits whether the second orthogonal frequency division multiplexing synchronization symbol is present, and

in response to determining that the second orthogonal frequency division multiplexing synchronization symbol is present:

receive the second orthogonal frequency division multiplexing synchronization symbol corresponding to a second scrambled bit sequence;

descramble the second scrambled bit sequence with a second scrambling sequence; and

decode a second group of signaling bits from the second descrambled bit sequence, wherein the first and second bit sequences have the same length, wherein the first scrambling sequence is generated by a pseudorandom binary sequence generator using a first initialization value, and wherein the second scrambling sequence is generated by the pseudorandom binary sequence generator using a second initialization value.

10. A computer program product comprising a non-transitory computer-readable medium bearing computer program code embodied therein for use with a computer, the computer program code comprising:

code for receiving an orthogonal frequency division multiplexing signal comprising a first orthogonal frequency division multiplexing symbol;

code for synchronizing a data frame based at least in part on the first orthogonal frequency division multiplexing symbols, wherein the first orthogonal frequency division multiplexing symbol corresponds to a first scrambled bit sequence;

code for descrambling the first scrambled bit sequence with a first scrambling sequence; and

code for decoding a first group of signaling bits from the first descrambled bit sequence and, wherein the first group of signaling bits indicates whether a next symbol comprises a second orthogonal frequency division multiplexing symbol as an additional synchronization symbol

code for determining from the first group of signaling bits whether the second orthogonal frequency division multiplexing synchronization symbol is present, and

in response to determining that the second orthogonal frequency division multiplexing synchronization symbol is present:

code for receiving the second orthogonal frequency division multiplexing synchronization symbol corresponding to a second scrambled bit sequence;

code for descrambling the second scrambled bit sequence with a second scrambling sequence; and

code for decoding a second group of signaling bits from the second descrambled bit sequence, wherein the first and second bit sequences have the same length, wherein the first scrambling sequence is generated by a pseudorandom binary sequence generator using a first initialization value, and wherein the second scrambling sequence is generated by the pseudorandom binary sequence generator using a second initialization value.