System and method for improved waveform and enhanced receiver algorithm for high penetration alerting in a mobile satellite communications system

1. A method comprising:

generating, by a processor, a message for transmission to a wireless terminal, wherein the message comprises a number of bits;

partitioning the message into a number of symbols, each symbol being composed of a distinct equal length portion of the message;

encoding the symbols via an FEC outer coding to generate a number of outer coded symbols;

encoding each of the outer coded symbols based on an orthogonal sequence inner coding to generate a respective inner coded symbol, wherein each outer coded symbol is coded based on a distinct corresponding one of a plurality of binary orthogonal sequences; and

modulating the inner coded symbols based on a binary modulation scheme, and pulse shaping the modulated inner coded symbols to generate a plurality of message bursts for transmission to the wireless terminal; and

wherein each message burst reflects a group of a uniform number of the inner coded symbols, wherein the grouping of the inner coded symbols within the message bursts facilitates joint sequence detection by a receiver of the wireless terminal, and wherein each message burst exhibits relatively low peak-to-average power ratio.

2. The method of claim 1 , wherein the binary modulation scheme comprises one of binary phase shift keying (BPSK), π/2 BPSK, quadrature phase shift keying (QPSK), and offset quadrature phase shift keying (OQPSK).

3. The method of claim 1 , wherein the encoding of the outer coded symbols further comprises scrambling each message burst based on a binary scrambling sequence.

4. The method of claim 1 , wherein the distinct corresponding binary orthogonal sequence, based upon which each outer coded symbol is encoded, is based on a value of the respective outer coded symbol.

5. The method of claim 4 , wherein each outer coded symbol is four bits in length, and the orthogonal sequence inner coding comprises a 16-ary coding based on sixteen binary orthogonal sequences with each sequence corresponding to a respective one of the potential four-bit values of the outer coded symbols.

6. The method of claim 5 , wherein the sixteen four-bit value outer coded symbol values and corresponding binary orthogonal sequences are as follows:

4-Bit Outer

Coded Symbol

Value

Binary Orthogonal Sequences (76 elements per Sequence)

0000

0001001100001111001100000000111111001111111100111111000000001100111100001100

0001

0011000100110000111100110000000011111100111111110011111100000000110011110000

0010

0000001100010011000011110011000000001111110011111111001111110000000011001111

0011

0011110000110001001100001111001100000000111111001111111100111111000000001100

0100

0011001111000011000100110000111100110000000011111100111111110011111100000000

0101

0000001100111100001100010011000011110011000000001111110011111111001111110000

0110

0000000000110011110000110001001100001111001100000000111111001111111100111111

0111

0011110000000011001111000011000100110000111100110000000011111100111111110011

1000

1111000000111111110011000011110011101100111100001100111111110000001100000000

1001

1100001100000011111111001100001111001110110011110000110011111111000000110000

1010

1100000000110000001111111100110000111100111011001111000011001111111100000011

1011

1100110000000011000000111111110011000011110011101100111100001100111111110000

1100

1100000011000000001100000011111111001100001111001110110011110000110011111111

1101

1111110000001100000000110000001111111100110000111100111011001111000011001111

1110

1111111111000000110000000011000000111111110011000011110011101100111100001100

1111

 1111001111111100000011000000001100000011111111001100001111001110110011110000.

7. The method of claim 6 , wherein the encoding of the outer coded symbols further comprises scrambling each message burst based on a 228-bit binary scrambling sequence, as follows:

00010011000110111100010000100101000011111000110000010101111

01111110011010110101011101100100110010110111000100011011010

00011110110110000010100100100000011000111000000010000101111

111100000110101010111111011001100101010010001000110

8. The method of claim 7 , wherein the message comprises 36 information bits, the message is partitioned into nine 4-bit symbols, the FEC outer coding generates fifteen 4-bit outer coded symbols, and each message burst reflects a group of three of the inner coded symbols.

9. The method of claim 8 , wherein the binary modulation scheme comprises a π/2 BPSK scheme applied as follows:

S l =(−1) d l *e jl(π/2)

where d l denotes the scrambled bits, and S l denotes the π/2 BPSK modulated symbol, and the outer coding comprises a Reed-Solomon (15,9) outer code, with a Galois field of 2 4 (GF(2 4 )).

10. An apparatus comprising:

a processor module configured to generate a message for transmission to a wireless terminal, wherein the message comprises a number of bits, and to partition the message into a number of symbols, each symbol being composed of a distinct equal length portion of the message;

an encoder module configured to encode the symbols via an FEC outer coding to generate a number of outer coded symbols, and to encode each of the outer coded symbols based on an orthogonal sequence inner coding to generate a respective inner coded symbol, wherein each outer coded symbol is coded based on a distinct corresponding one of a plurality of binary orthogonal sequences; and

a modulator module configured to modulate the inner coded symbols based on a binary modulation scheme; and

one or more pulse shaping filters to pulse shape the modulated inner coded symbols to generate a plurality of message bursts for transmission to the wireless terminal; and

wherein each message burst reflects a group of a uniform number of the inner coded symbols, wherein the grouping of the inner coded symbols within the message bursts facilitates joint sequence detection by a receiver of the wireless terminal, and wherein each message burst exhibits relatively low peak-to-average power ratio.

11. The apparatus of claim 10 , wherein the binary modulation scheme comprises one of binary phase shift keying (BPSK), π/2 BPSK, quadrature phase shift keying (QPSK), and offset quadrature phase shift keying (OQPSK).

12. The apparatus of claim 10 , wherein, as part of the encoding of the outer coded symbols, the encoder is further configured to scramble each message burst based on a binary scrambling sequence.

13. The apparatus of claim 10 , wherein the distinct corresponding binary orthogonal sequence, based upon which each outer coded symbol is encoded, is based on a value of the respective outer coded symbol.

14. The apparatus of claim 13 , wherein each outer coded symbol is four bits in length, and the orthogonal sequence inner coding comprises a 16-ary coding based on sixteen binary orthogonal sequences with each sequence corresponding to a respective one of the potential four-bit values of the outer coded symbols.

15. The apparatus of claim 14 , wherein the sixteen four-bit value outer coded symbol values and corresponding binary orthogonal sequences are as follows:

4-Bit Outer

Coded Symbol

Value

Binary Orthogonal Sequences (76 elements per Sequence)

0000

0001001100001111001100000000111111001111111100111111000000001100111100001100

0001

0011000100110000111100110000000011111100111111110011111100000000110011110000

0010

0000001100010011000011110011000000001111110011111111001111110000000011001111

0011

0011110000110001001100001111001100000000111111001111111100111111000000001100

0100

0011001111000011000100110000111100110000000011111100111111110011111100000000

0101

0000001100111100001100010011000011110011000000001111110011111111001111110000

0110

0000000000110011110000110001001100001111001100000000111111001111111100111111

0111

0011110000000011001111000011000100110000111100110000000011111100111111110011

1000

1111000000111111110011000011110011101100111100001100111111110000001100000000

1001

1100001100000011111111001100001111001110110011110000110011111111000000110000

1010

1100000000110000001111111100110000111100111011001111000011001111111100000011

1011

1100110000000011000000111111110011000011110011101100111100001100111111110000

1100

1100000011000000001100000011111111001100001111001110110011110000110011111111

1101

1111110000001100000000110000001111111100110000111100111011001111000011001111

1110

1111111111000000110000000011000000111111110011000011110011101100111100001100

1111

 1111001111111100000011000000001100000011111111001100001111001110110011110000.

16. The apparatus of claim 15 , wherein, as part of the encoding of the outer coded symbols, the encoder is further configured to scramble each message burst based on a 228-bit binary scrambling sequence, as follows:

00010011000110111100010000100101000011111000110000010101111

01111110011010110101011101100100110010110111000100011011010

00011110110110000010100100100000011000111000000010000101111

111100000110101010111111011001100101010010001000110

17. The apparatus of claim 16 , wherein the message comprises 36 information bits, the message is partitioned into nine 4-bit symbols, the FEC outer coding generates fifteen 4-bit outer coded symbols, and each message burst reflects a group of three of the inner coded symbols.

18. The apparatus of claim 17 , wherein the binary modulation scheme comprises a π/2 BPSK scheme applied as follows:

S l =(−1) d l *e jl(m/2)

where d l denotes the scrambled bits, and S l denotes the π/2 BPSK modulated symbol, and the outer coding comprises a Reed-Solomon (15,9) outer code, with a Galois field of 2 4 (GF(2 4 )).