Systems and methods for adaptive hybrid automatic retransmission requests
View Patent ↗Packet transmission is performed in a wireless adaptive hybrid automatic repeat request transmission system. An optimized assignment rate for a packet is determined based at least in part on a maximal number of transmission attempts and a long term signal to noise ration of the wireless transmission system, an optimized quadrature amplitude modulation set is determined for the packet based at least in part on the maximal number of transmission attempts and the long term signal to noise ration of the wireless transmission system, and information related to the packet is transmitted based at least in part on the determined optimized assignment rate and determined optimized quadrature amplitude modulation set.
1. A method of packet transmission in a wireless adaptive hybrid automatic repeat request transmission system with incremental redundancy comprising:
determining an assignment rate and modulation set {(λ l ,M l ) l=1, . . . , L} for a packet based at least in part on a maximal number of L transmission attempts and a long term signal to noise ration of the wireless transmission system which maximize the average throughput of the hybrid automatic repeat request transmission system given by
η
TC
=
(
1
-
p
(
L
)
)
r
0
λ
1
2
m
1
(
1
+
∑
l
=
1
L
-
1
λ
l
+
1
2
m
l
+
1
p
(
l
)
)
,
where λ l ,
∑
l
=
1
L
λ
l
≤
1
,
and M l denote the assignment rate and the M l -QAM modulation for the lth transmission block in a hybrid ARQ transmission of a packet, respectively, 2m l is the number of bits in the M 1 -QAM modulation where
m
l
=
log
2
M
l
2
,
l=1, . . . , L and p(l), denotes the packet error probability after l transmissions; and
transmitting information related to the packet based at least in part on the determined assignment rate and a determined quadrature amplitude modulation (λ l ,M l ), l=1 , . . . , L for the lth transmission of a maximal number of L transmission attempts for a packet in a hybrid ARQ transmission process.
2. The method of claim 1 further comprising:
determining the maximal number of transmission attempts; and
determining the long term signal to noise ration of the wireless transmission system.
3. The method of claim 1 further comprising:
assigning coded bits to a codeword based on the determined optimized assignment rate;
modulating the codeword using quadrature amplitude modulation into a block of quadrature amplitude modulation symbols; and
wherein transmitting information related to the packet comprises transmitting the block of quadrature amplitude modulation symbols.
4. The method of claim 1 wherein determining an optimized said assignment rate for the modulation set using a genetic process further comprises:
determining a modulation candidate from the modulation set;
determining a number of randomized candidates, a maximal iteration number, and a step size; and
determining an optimized said assignment rate and throughput for the modulation set using the genetic process.
5. The method of claim 4 wherein determining an optimized assignment rate and throughput for the modulation set using the genetic process comprises repeating the steps of:
(a) generating a determined number of sets of candidate assignment rates randomly;
(b) determining the error rates of every set of candidate assignment rates p(l);
(c) determining the throughput of the candidate assignment rates
η
TC
=
(
1
-
p
(
L
)
)
r
0
λ
1
2
m
1
+
∑
l
=
1
L
-
1
λ
l
+
1
2
m
l
+
1
p
(
l
)
;
(d) determining an optimal said assignment rate and throughput;
(e) determining if the maximal iteration number has been reached; and
if the maximal iteration number has not been reached, performing steps b through e.
6. The method of claim 5 further comprising:
outputting the determined optimized said assignment rate; and
outputting the determined throughput.
7. A non-transitory machine readable medium having program instructions stored thereon, the instructions capable of execution by a processor and defining the steps of:
determining an assignment rate and modulation set {(λ l , M l ), l=1 , . . . , L } for a packet based at least in part on a maximal number of L transmission attempts and a long term signal to noise ration of the wireless transmission system which maximize the average throughput of the hybrid automatic repeat request transmission system given by
η
TC
=
(
1
-
p
(
L
)
)
r
0
λ
1
2
m
1
(
1
+
∑
l
=
1
L
-
1
λ
l
+
1
2
m
l
+
1
p
(
l
)
)
,
where λ l ,
∑
l
=
1
L
λ
l
≤
1
,
and M l denote the assignment rate and the M l -QAM modulation, for the lth transmission block in a hybrid ARQ transmission of a packet respectively, 2m l is the number of bits in the M l -QAM modulation where
m
l
=
log
2
M
l
2
,
l=1, . . . , L and p(l), denotes the packet error probability after l transmissions;
and
transmitting information related to the packet based at least in part on the determined assignment rate and a determined quadrature amplitude modulation (λ l , M l ), l=1, . . . , L for the lth transmission of a maximal number of L transmission attempts for a packet in a hybrid ARQ transmission process.
8. The machine readable medium of claim 7 wherein the instructions further define the steps of:
determining the maximal number of transmission attempts; and
determining the long term signal to noise ration of the wireless transmission system.
9. The machine readable medium of claim 7 wherein the instructions further define the steps of:
assigning coded bits to a codeword based on the determined optimized assignment rate;
modulating the codeword using quadrature amplitude modulation into a block of quadrature amplitude modulation symbols; and
wherein transmitting information related to the packet comprises transmitting the block of quadrature amplitude modulation symbols.
10. The machine readable medium of claim 7 wherein the instructions further define the steps of:
determining a modulation set;
determining an optimized said assignment rate for the modulation set using a genetic process; and
determining if the determined optimized said assignment rate for the modulation set maximizes throughput for the modulation set.
11. The machine readable medium of claim 10 wherein the instructions for determining an optimized said assignment rate for the modulation set using a genetic process further define the steps of:
determining a modulation candidate from the modulation set;
determining a number of randomized candidates, a maximal iteration number, and a step size; and
determining an optimized said assignment rate and throughput for the modulation set using the genetic process.
12. The machine readable medium of claim 11 wherein the instructions for determining an optimal said assignment rate and throughput for the modulation set using the genetic process further define repeating the steps of:
(a) generating a determined number of sets of candidate assignment rates randomly;
(b) determining the error rates of every set of candidate assignment rates p(l);
(c) determining the throughput of the candidate assignment rates
η
TC
=
(
1
-
p
(
L
)
)
r
0
λ
1
2
m
1
+
∑
l
=
1
L
-
1
λ
l
+
1
2
m
l
+
1
p
(
l
)
;
(d) determining the optimized said assignment rate and throughput;
(e) determining if the maximal iteration number has been reached; and
if the maximal iteration number has not been reached, performing steps b through e.