Method and system for providing spread scrambled coded multiple access (SSCMA)
View Patent ↗A spread scrambled multiple access (SSCMA) scheme is described. A first encoded bit stream of a first terminal is scrambled according to a first scrambling signature. A second encoded bit stream of a second terminal is scrambled according to a second scrambling signature. The first scrambled bit stream is spread to match a communication channel bandwidth. The second scrambled bit stream is spread to match the communication channel bandwidth.
1. A method, comprising:
encoding a first bit stream of a first terminal based on a turbo encoding scheme, scrambling the encoded first bit stream according to a first scrambling signature with a first initial vector, and spreading the scrambled and encoded first bit stream to match a communication channel bandwidth;
encoding a second bit stream of a second terminal based on the turbo encoding scheme, scrambling the encoded second bit stream according to a second scrambling signature with a second initial vector, and spreading the scrambled and encoded second bit stream to match the communication channel bandwidth; and
outputting a composite signal based on the turbo encoded first bit stream and the turbo encoded second bit stream;
wherein the use of the first initial vector with the first scrambling signature for the first bit stream and the second initial vector with the second scrambling signature for the second bit stream serves to distinguish the first bit stream of the first terminal from the second bit stream of the second terminal to provide a multiple access scheme; and
wherein the turbo code encoding utilizes constituent encoding having a transfer function:
G
(
D
)
=
[
n
0
(
D
)
d
(
D
)
,
n
1
(
D
)
d
(
D
)
,
…
n
6
(
D
)
d
(
D
)
]
where,
d ( D )=1+ D 3
n 0 ( D )=1
n 1 ( D )=1+ D 2
n 2 ( D )=1+ D 2 +D 3
n 3 ( D )=1+ D+D 2 +D 3
n 4 ( D )=1+ D+D 3
n 5 ( D )=1+ D+D 2
n 6 ( D )=1+ D.
2. A method according to claim 1 , wherein the encoded bit streams are based on a low code rate of R/F, where R is a forward error correction (FEC) code rate, and F is a spreading factor.
3. A method according to claim 1 , wherein the spreading is performed using at least one of direct-sequence spread spectrum, frequency-hopping spread spectrum, chirp spread spectrum, and time-hopping spread spectrum.
4. A method according to claim 1 , wherein at least one of the first and second terminals is a data collection platform or a supervisory control and data acquisition platform.
5. A system, comprising:
a first terminal, including a first encoder module configured to encode a first bit stream based on a turbo encoding scheme, a first scrambler module configured to scramble the encoded first bit stream according to a first scrambling signature with a first initial vector, and a first spreader module configured to spread the scrambled and encoded first bit stream to match a communication channel bandwidth;
a second terminal, including a second encoder module configured to encode a second bit stream based on the turbo encoding scheme, a second scrambler module configured to scramble the encoded second bit stream according to a second scrambling signature with a second initial vector, and a second spreader module configured to spread the scrambled and encoded second bit stream to match the communication channel bandwidth;
wherein a composite signal is output based on the turbo encoded first bit stream and the turbo encoded second bit stream;
wherein the use of the first initial vector with the first scrambling signature for the first bit stream and the second initial vector with the second scrambling signature for the second bit stream serves to distinguish the first bit stream of the first terminal from the second bit stream of the second terminal to provide a multiple access scheme; and
wherein the turbo code encoding utilizes constituent wherein the encoding utilizes constituent encoding having a transfer function:
G
(
D
)
=
[
n
0
(
D
)
d
(
D
)
,
n
1
(
D
)
d
(
D
)
,
…
n
6
(
D
)
d
(
D
)
]
where,
d ( D )=1+ D 3
n 0 ( D )=1
n 1 ( D )=1+ D 2
n 2 ( D )=1+ D 2 +D 3
n 3 ( D )=1+ D+D 2 +D 3
n 4 ( D )=1+ D+D 3
n 5 ( D )=1+ D+D 2
n 6 ( D )=1+ D.
6. A system according to claim 5 , wherein the encoded bit streams are based on a low code rate of R/F, where R is a forward error correction (FEC) code rate, and F is a spreading factor.
7. A system according to claim 5 , wherein at least one of the first spreader module and the second spreader module comprises at least one of a direct-sequence spreader, a frequency hopping spreader, a chip spreader, and a time-hopping spreader.
8. A system to claim 5 , wherein at least one of the first and second terminals is a data collection platform or a supervisory control and data acquisition platform.