Data receiver with improved response to long and short term fading
View Patent ↗The invention relates to apparatus for the receipt of digital data which is transmitted as a data signal from a remote location and a method by which the receiving apparatus can be designed with a configuration to improve the ability to receive the data signal. The design of the configuration is generated with reference to at least one decision metric which is adapted to suit the known characteristics of the data signal which is being received.
1. A broadcast receiver with improved response to long and short term fading which comprises:
a processor configured to receive a data signal which is assessed with respect to a decision metric derived upon utilising the probability density function of a Suzuki distribution in a closed form:
p
a
l
(
a
l
)
=
(
5
2
)
1
8
σ
2
a
1
ⅇ
-
μ
2
2
σ
2
σ
2
π
Γ
(
1
-
1
8
σ
2
-
μ
2
σ
2
)
(
-
1
8
σ
2
-
a
l
2
2
)
-
1
+
1
8
σ
2
+
μ
2
σ
2
where σ and μ denote the variance and mean value respectively of the Lognormal distribution, in order to take into account potential impairment of the said data signal.
2. A broadcast receiver according to claim 1 wherein the receiver is optimised in a plurality of conditions with respect to the geographical location to which the receiver is to be used.
3. A broadcast receiver according to claim 1 wherein the data signal impairment is with respect to the fading of the data signal channel.
4. A broadcast receiver according to claim 1 wherein when the amplitudes of the data signal are independent with first order probability density functions {pα l (a l )} l=1 Lp , and the phase and delay values are known, the decision metric derived from the Suzuki distribution is:
Λ k =ln [ p ({ r l ( t )} l=1 Lp |s k ( t ),{θ l } l=1 Lp ,{τ l } l=1 Lp )].
5. A broadcast receiver according to claim 1 wherein the decision metric used when the phase value of the data signal is known but the amplitudes and delay values are not known is:
Λ
k
=
ln
[
p
(
{
r
l
(
t
)
}
l
=
1
Lp
❘
s
k
(
t
)
,
{
θ
l
}
l
=
1
Lp
)
]
=
ln
(
K
(
B
-
A
)
∏
l
=
1
L
p
(
5
2
)
1
8
σ
2
ⅇ
-
μ
2
2
σ
2
2
σ
2
π
Γ
(
1
-
1
8
σ
2
-
μ
2
σ
2
)
[
N
l
E
k
]
-
1
+
1
+
4
μ
4
σ
2
Γ
(
1
+
4
μ
8
σ
2
-
1
2
)
F
1
1
(
1
+
4
μ
8
σ
2
-
1
2
,
1
2
,
ⅇ
-
j2θ
l
y
kl
2
(
τ
)
4
E
k
N
l
)
+
[
ⅇ
-
jθ
l
y
kl
(
τ
)
N
l
]
N
l
E
k
Γ
(
1
+
4
μ
8
σ
2
)
F
1
1
(
1
+
4
μ
8
σ
2
,
3
2
,
ⅇ
-
j2θ
l
y
kl
2
(
τ
)
4
E
k
N
l
)
)
and
Λ
k
=
ln
[
p
(
{
r
l
(
t
)
}
l
=
1
Lp
❘
s
k
(
t
)
,
{
θ
l
}
l
=
1
Lp
)
]
=
ln
(
K
(
B
-
A
)
∏
l
=
1
L
p
(
5
2
)
1
8
σ
2
ⅇ
-
μ
2
2
σ
2
2
σ
2
π
Γ
(
1
-
1
8
σ
2
-
μ
2
σ
2
)
[
N
l
E
k
]
-
1
+
1
+
4
μ
4
σ
2
Γ
(
1
+
4
μ
8
σ
2
-
1
2
)
*
2
1
-
1
8
σ
2
-
μ
2
σ
2
F
1
1
(
1
+
4
μ
8
σ
2
-
1
2
,
1
2
,
ⅇ
-
j2θ
l
y
kl
2
(
τ
)
4
E
k
N
l
)
+
[
ⅇ
-
jθ
l
y
kl
(
τ
)
N
l
]
N
l
E
k
Γ
(
1
+
4
μ
8
σ
2
)
F
1
1
(
1
+
4
μ
8
σ
2
,
3
2
,
ⅇ
-
j2θ
l
y
kl
2
(
τ
)
4
E
k
N
l
)
)
.
6. A broadcast receiver according to claim 1 wherein the decision metric used in the case of known delay and amplitude values of the data signal but the phase value is unknown is:
Λ
k
=
ln
[
p
(
{
r
l
(
t
)
}
l
=
1
Lp
❘
s
k
(
t
)
,
{
α
l
}
l
=
1
Lp
,
{
τ
l
}
l
=
1
Lp
)
]
=
K
∑
l
=
1
L
p
ln
[
ⅇ
-
a
l
2
E
k
N
l
I
o
(
a
l
N
l
y
kl
(
τ
l
)
)
]
.
7. A broadcast receiver according to claim 1 wherein the decision metric used in the case of a known delay value in the data signal but unknown amplitude and phase values is:
Λ k =ln [ p ({ r l ( t )} l=1 Lp |s k ( t ),{τ l } l=1 Lp )].
8. A broadcast receiver according to claim 1 wherein the decision metric used in the case when the delay, amplitude and phase values are unknown is:
Λ
k
=
ln
[
p
(
{
r
l
(
t
)
}
l
=
1
Lp
❘
s
k
(
t
)
)
]
=
ln
[
K
(
B
-
A
)
∏
l
=
1
L
p
(
5
2
)
1
8
σ
2
ⅇ
-
μ
2
2
σ
2
σ
2
n
Γ
(
1
-
1
8
σ
2
-
μ
2
σ
2
)
]
1
2
[
E
k
N
l
]
-
1
+
4
μ
8
σ
2
Γ
(
1
+
4
μ
8
σ
2
)
and
ln
[
K
(
B
-
A
)
∏
l
=
1
L
p
(
5
2
)
1
8
σ
2
ⅇ
-
μ
2
2
σ
2
4
σπ
2
Γ
(
1
-
1
8
σ
2
-
μ
2
σ
2
)
[
E
k
N
l
]
1
4
-
1
+
4
μ
8
σ
2
2
1
2
-
1
8
σ
2
-
μ
2
σ
2
y
kl
(
τ
l
)
N
l
(
Γ
(
1
+
4
μ
8
σ
2
-
1
4
)
F
1
1
(
1
+
4
μ
8
σ
2
-
1
4
,
1
2
,
y
kl
2
(
τ
)
4
E
k
N
l
)
-
[
y
kl
(
τ
)
E
k
N
l
]
Γ
(
1
+
4
μ
8
σ
2
+
1
4
)
F
1
1
(
1
+
4
μ
8
σ
2
+
1
4
,
3
2
,
y
kl
2
(
τ
)
4
E
k
N
l
)
)
]
.
9. A broadcast data receiver according to claim 1 wherein the configuration of the receiver includes details relating to coherent detection as well as non-coherent detection.
10. A broadcast receiver according to claim 1 wherein the configuration of the receiver includes details of possible modulation schemes to be used.
11. A broadcast receiver according to claim 1 wherein the receiver is configured to receive data signals which are provided using shaping pulses.
12. A method of configuring receiving and/or processing apparatus for at least one data signal received from a remote transmitting location, said method comprising the steps of:
identifying a data signal to be received; and
configuring a receiving and/or processing apparatus based on said identified signal with reference to a decision metric derived upon utilising the probability density function of a Suzuki distribution in a closed form:
p
a
l
(
a
l
)
=
(
5
2
)
1
8
σ
2
a
1
ⅇ
-
μ
2
2
σ
2
σ
2
π
Γ
(
1
-
1
8
σ
2
-
μ
2
σ
2
)
(
-
1
8
σ
2
-
a
l
2
2
)
-
1
+
1
8
σ
2
+
μ
2
σ
2
where σ and μ denote the variance and mean value respectively of the Lognormal distribution, in order to take into account potential impairment of the said data signal.
13. A method according to claim 12 wherein the method includes the step of identifying the geographical location at which the said apparatus is to be used.