US2015003597A1PendingUtilityA1
Method and device for adjusting a power allocation of users in a digital subscriber line environment
Est. expiryMay 12, 2030(~3.8 yrs left)· nominal 20-yr term from priority
H04B 3/32H04L 5/0007H04L 5/0037H04B 3/487H04L 5/00
51
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Claims
Abstract
A method and a device adjust a power allocation of users in a digital subscriber line environment. An intermediate power allocation is determined for at least one user initializing with the digital subscriber line environment based on a new power allocation determined for the digital subscriber line environment containing the at least one user. The intermediate power allocation provides a predefined minimum signal-to-noise ratio margin for the active users of the digital subscriber line environment. Furthermore, a communication system can contain such a device.
Claims
exact text as granted — not AI-modified1 . A method for adjusting a power allocation of users in a digital subscriber line environment, the method comprising:
determining an intermediate power allocation for at least one user initializing with the digital subscriber line environment based on a new power allocation determined for the digital subscriber line environment containing the at least one user; the intermediate power allocation providing a predefined minimum signal-to-noise ratio (SNR) margin for active users of the digital subscriber line environment.
2 . The method according to claim 1 , which further comprises determining at least one intermediate power allocation that converges towards the new power allocation.
3 . The method according to claim 1 , wherein the digital subscriber line environment contains at least one dynamic spectrum management system, which is managed by a spectrum management center.
4 . The method according to claim 1 , wherein the predefined minimum SNR margin is provided for the intermediate power allocation or individually for each of the users for which the intermediate power allocation is determined, for every subcarrier, a portion of the users or a portion of the subcarriers.
5 . The method according to claim 1 , which further comprises determining the intermediate power allocation utilizing spectral limitation masks as well as a limited power budget per the at least one user, the limited power budget being distributed among tones of a discrete multi-tone modulation scheme.
6 . The method according to claim 1 , which further comprises determining the intermediate power allocation such that a distance metric between an actual power allocation and the new power allocation is reduced.
7 . The method according to claim 6 , wherein the distance metric is reduced meeting at least one of the following constraints:
a total transmit power is limited; a transmit power on each sub-carrier or tone is limited individually by a power spectrum density mask; and for the minimum SNR margin, a data rate achieved by each of the users with an obtained power allocation equals or exceeds a predetermined target data rate.
8 . The method according to claim 6 , wherein the distance metric according to Δ(s(i), s new ) comprises at least one property selected from the group consisting of:
Δ is convex in s k n ;
Δ is separable in s k n ; and
Δ(s(i), s new ) has a unique global minimum for s(i)=s new .
9 . The method according to claim 6 , wherein the distance metric comprises a distance function selected from the group consisting of:
Δ
(
s
(
i
)
,
s
new
)
=
∑
n
∑
k
(
s
k
n
(
i
)
s
k
,
new
n
-
1
)
2
;
Δ
(
s
(
i
)
,
s
new
)
=
∑
n
∑
k
α
k
n
(
s
k
n
(
i
)
-
s
k
,
new
n
)
2
;
and
Δ
(
s
(
i
)
,
s
new
)
=
∑
n
∑
k
α
k
n
(
s
k
n5
(
i
)
s
k
,
new
n
-
s
k
,
new
n
s
k
n
(
i
)
)
2
;
wherein
s k n denotes a power spectrum density of a transmit signal of a user n;
k denotes a subchannel or tone;
s new is the new power allocation; and
s(i) is the intermediate power allocation at a step i.
10 . The method according to claim 1 , wherein the intermediate power allocation is determined by solving a following optimization problem:
min
s
k
n
(
i
)
∀
n
∈
i
,
k
Δ
(
s
(
i
)
,
s
new
)
s
.
t
.
R
n
(
γ
_
)
s
(
i
)
≥
R
target
n
∀
n
∑
k
s
k
n
(
i
)
≤
P
max
n
∀
n
0
≤
s
k
n
(
i
)
≤
s
k
,
mask
n
∀
n
,
k
wherein
n∈G i ⊂ N is the user;
G i denotes a group containing the at least one user initializing with the digital subscriber line environment;
N denotes the users sharing a same binder;
s k n denotes a power spectrum density of a transmit signal of a user n;
s k,mask n is a PSD mask determined by a band profile used;
k determines a subchannel or tone;
s new is the new power allocation;
s(i) is the intermediate power allocation at a step i;
γ is the predefined minimum SNR margin;
R n is a data rate of the user n;
R target n is a target data rate of user n; and
P max n is a maximum aggregate transmit power of the user n.
11 . The method according to claim 10 , which further comprises solving the optimization problem via a dual decomposition combined with a convex relaxation.
12 . The method according to claim 11 , which further comprises solving the optimization problem by decomposing a Lagrangian
Λ
=
Δ
(
s
(
i
)
,
s
new
)
+
∑
n
ω
n
(
R
target
n
-
R
n
(
i
)
)
+
∑
n
λ
n
(
∑
k
s
k
n
(
i
)
-
P
max
n
)
wherein
ω n is a dual variable corresponding to a data rate constraint of the user n; and
λ n is a dual variable corresponding to a power constraint,
into per-tone Lagrangians Λ k according to
Λ
=
∑
k
Λ
k
+
∑
n
ω
n
R
target
n
-
∑
n
λ
n
P
max
n
const
.
in
s
(
i
)
with
Λ
k
=
∑
n
(
s
k
n
(
i
)
s
k
,
new
n
-
1
)
2
+
∑
n
λ
n
s
k
n
(
i
)
-
f
s
∑
n
ω
n
log
2
(
1
+
1
γ
¨
Γ
g
k
n
,
n
s
k
n
(
i
)
∑
m
≠
n
g
k
n
,
m
(
i
)
+
σ
k
2
)
.
13 . The method according to claim 12 , wherein a dual problem
max
ω
n
,
λ
n
∀
n
∈
i
min
s
k
n
(
i
)
∀
n
∈
i
,
k
Λ
s
.
t
.
ω
n
,
λ
n
≥
0
∀
n
0
≤
s
k
n
(
i
)
≤
s
k
,
mask
n
∀
n
,
k
of the optimization problem is solved by solving K independent sub-problems
min
s
k
n
(
i
)
∀
n
∈
i
Λ
k
s
.
t
.
0
≤
s
k
n
(
i
)
≤
s
k
,
mask
n
∀
n
per Lagrange multiplier search step.
14 . The method according to claim 10 , wherein:
at an initial step i=0, it is determined whether the minimum SNR margin γ with 1≦ γ ≦γ target exists so that the optimization problem is feasible for s(0); in case where the minimum SNR margin γ exists, the value is used to determine the at least one intermediate power allocation; in case no such minimum SNR margin γ ≧1 exists, a set G 0 is augmented by at least one additional user whose power allocation is re-shaped at the time instant t=t 0 .
15 . The method according to claim 1 , which further comprises determining the intermediate power allocation such that a distance metric between an actual power allocation and the new power allocation is minimized.
16 . A device, comprising:
a processing unit programmed to adjust a power allocation of users in a digital subscriber line environment by determining an intermediate power allocation for at least one user initializing with the digital subscriber line environment based on a new power allocation determined for the digital subscriber line environment containing the at least one user; the intermediate power allocation providing a predefined minimum signal-to-noise ratio margin for active users of the digital subscriber line environment.
17 . The device according to claim 16 , wherein the device is selected from the group consisting of a modem, a digital subscriber line access multiplexer, a centralized network component, and a spectrum management center.
18 . A method for adjusting a power allocation of users in a digital subscriber line environment, the method comprising:
upon receiving a request by a new user to be initialized to the digital subscriber line environment, determining an intermediate power allocation for the new user initializing with the digital subscriber line environment based on a new power allocation determined for the digital subscriber line environment containing the new user; the intermediate power allocation providing for a predefined minimum signal-to-noise ratio margin for active users of the digital subscriber line environment.Cited by (0)
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