Method and apparatus for wireless data transmission subject to periodic signal blockages

1. A method, comprising:

segmenting a data stream into packets of a fixed-size for a burst-mode transmission over a wireless channel, wherein the transmission is subject to a periodic blockage, wherein the periodic blockage comprises at least two blockages occurring within a time period, and each blockage is of a respective duration and recurs at regular intervals based on the time period;

applying a forward error correction (FEC) outer code to the packets of the data stream for recovery of data erasures due to the periodic blockage, wherein the application of the FEC outer code comprises applying an error correction code to each of the packets to generate a respective codeblock;

interleaving each codeblock to substantially prevent erasure of consecutive parity bits within the codeblock by the periodic blockage, wherein the interleaving of each codeblock comprises writing each bit of the codeblock into an interleaver matrix of n rows and m columns in a row-by-row mode, shuffling the bits of each row within the row, and reading the shuffled bits from each row of the interleaver matrix in the row-by-row mode, and wherein the shuffling of the bits of each row comprises shuffling each bit of an original position k within the row to a new position within the row according to the following scheme: k→(k×c i ) mod m, where c i is a row-dependent constant; and

transmitting the encoded and interleaved codeblocks over the wireless channel, wherein a number of the data erasures occur within each codeblock due to the periodic blockage.

2. The method of claim 1 , wherein the FEC outer code comprises a low density parity check code configured to optimize the recovery of the number of data erasures within each codeblock.

3. The method of claim 1 , wherein c i and m are relatively prime.

4. The method of claim 1 , wherein the FEC outer code comprises a rate 4/5 low density parity check code, n=160, m=800, and the values of c i , i=0, 1, 2, ..., 159 are as follows:

313,

563,

667,

539,

343,

461,

 53,

181,

421,

531,

397,

703,

389,

721,

661,

551,

123,

133,

 41,

747,

789,

199,

561,

131,

 17,

629,

357,

333,

 41,

 99,

563,

233,

411,

437,

 47,

307,

779,

189,

311,

671,

603,

 83,

317,

379,

197,

769,

373,

621,

 69,

113,

553,

509,

431,

439,

673,

 9,

 23,

353,

671,

 77,

387,

401,

401,

363,

261,

797,

147,

207,

319,

649,

477,

 81,

 61,

753,

 79,

619,

 69,

267,

687,

379,

493,

187,

343,

201,

387,

757,

511,

507,

479,

677,

427,

727,

551,

559,

591,

621,

 17,

127,

237,

259,

 83,

583,

363,

731,

779,

217,

197,

103,

 29,

 19,

297,

171,

 27,

 43,

453,

307,

177,

737,

207,

259,

499,

159,

523,

783,

609,

 19,

791,

329,

281,

329,

 89,

103,

167,

353,

 9,

691,

333,

687,

153,

349,

501,

353,

457,

267,

691,

343,

317,

327,

533,

373,

393,

201,

201,

729,

431,

783,

 71,

613,

371,

441.

5. The method of claim 1 , further comprising:

adding a unique word (UW) to each of the packets of the data stream for acquisition of one or more of a frequency, carrier phase and symbol timing of the respective packet.

6. The method of claim 1 , further comprising:

applying a forward error correction (FEC) inner code to each encoded and interleaved codeblock.

7. The method of claim 6 , wherein the FEC inner code comprises one of a low density parity check code (LDPC), a convolutional code, and a turbo code.

8. The method of claim 1 , wherein:

the wireless channel comprises a channel in a satellite communications system;

the transmission comprises a data transmission of a satellite terminal installed on a helicopter having multiple rotor blades; and

each blockage within the time period comprises a blockage by a blade of a respective one of the rotors.

9. An apparatus, comprising:

at least one processor; and

at least one memory including computer program code for one or more programs,

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

segment a data stream into packets of a fixed-size for a burst-mode transmission over a wireless channel, wherein the transmission is subject to a periodic blockage, wherein the periodic blockage comprises at least two blockages occurring within a time period, and each blockage is of a respective duration and recurs at regular intervals based on the time period;

apply a forward error correction (FEC) outer code to the packets of the data stream for recovery of data erasures due to the periodic blockage, wherein the application of the FEC outer code comprises applying an error correction code to each of the packets to generate a respective codeblock;

interleave each codeblock to substantially prevent erasure of consecutive parity bits within the codeblock by the periodic blockage, wherein the interleaving of each codeblock comprises writing each bit of the codeblock into an interleaver matrix of n rows and m columns in a row-by-row mode, shuffling the bits of each row within the row, and reading the shuffled bits from each row of the interleaver matrix in the row-by-row mode, and wherein the shuffling of the bits of each row comprises shuffling each bit of an original position k within the row to a new position within the row according to the following scheme:

k→(k×c i ) mod m, where c i is a row-dependent constant; and

transmit the encoded and interleaved codeblocks over the wireless channel, wherein a number of the data erasures occur within each codeblock due to the periodic blockage.

10. The apparatus of claim 9 , wherein the FEC outer code comprises a low density parity check code configured to optimize the recovery of the number of data erasures within each codeblock.

11. The apparatus of claim 9 , wherein c i and m are relatively prime.

12. The apparatus of claim 9 , wherein the FEC outer code comprises a rate 4/5 low density parity check code, n=160, m=800, and the values of c i , i=0, 1, 2, ..., 159 are as follows:

313,

563,

667,

539,

343,

461,

 53,

181,

421,

531,

397,

703,

389,

721,

661,

551,

123,

133,

 41,

747,

789,

199,

561,

131,

 17,

629,

357,

333,

 41,

 99,

563,

233,

411,

437,

 47,

307,

779,

189,

311,

671,

603,

 83,

317,

379,

197,

769,

373,

621,

 69,

113,

553,

509,

431,

439,

673,

 9,

 23,

353,

671,

 77,

387,

401,

401,

363,

261,

797,

147,

207,

319,

649,

477,

 81,

 61,

753,

 79,

619,

 69,

267,

687,

379,

493,

187,

343,

201,

387,

757,

511,

507,

479,

677,

427,

727,

551,

559,

591,

621,

 17,

127,

237,

259,

 83,

583,

363,

731,

779,

217,

197,

103,

 29,

 19,

297,

171,

 27,

 43,

453,

307,

177,

737,

207,

259,

499,

159,

523,

783,

609,

 19,

791,

329,

281,

329,

 89,

103,

167,

353,

 9,

691,

333,

687,

153,

349,

501,

353,

457,

267,

691,

343,

317,

327,

533,

373,

393,

201,

201,

729,

431,

783,

 71,

613,

371,

441.

13. The apparatus of claim 9 , wherein the apparatus is caused to further perform the following:

add a unique word (UW) to each of the packets of the data stream for acquisition of one or more of a frequency, carrier phase and symbol timing of the respective packet.

14. The apparatus of claim 9 , wherein the apparatus is caused to further perform the following:

apply a forward error correction (FEC) inner code to each encoded and interleaved codeblock.

15. The apparatus of claim 14 , wherein the FEC inner code comprises one of a low density parity check code (LDPC), a convolutional code, and a turbo code.

16. The apparatus of claim 9 , wherein:

the wireless channel comprises a channel in a satellite communications system;

the apparatus consists of or is part of a satellite terminal located on a helicopter having multiple rotor blades;

the transmission comprises a data transmission of the satellite terminal; and

each blockage within the time period comprises a blockage by a blade of a respective one of the rotors.