Method for adaptively allocating resources in communication system
View Patent ↗A method for adaptively allocating resource can be simply implemented for reducing degradation of performance by effectively separating operations of sub-channel and time slot allocation and selection of modulation method and sequentially processing each of operations. A method for adaptively allocating resource in a communication system to sequentially process sub-carrier/time slot allocation and modulation method selection efficiently includes the step of a) computing average channel gains of sub-carriers/time slots for each user by using channel gains of sub-carriers/time slots for each user; b) computing average numbers of bits for each user by using required data rates and average channel gains of sub-carriers/time slots for each user; c) computing the number of sub-carriers/time slots allocated to each user and allocating the sub-carriers/time slots to each user; and d) selecting a modulation method with respect to each sub-carrier/time slot.
1. A method for adaptively allocating resources in a communication system by subsequently performing sub-carrier/time slot allocation and modulation selection processes, the method comprising the steps of:
a) computing average channel gains of sub-carriers/time slots for each user based on channel gains of sub-carriers/time slots for each user;
b) computing average numbers of bits of sub-carriers/time slots for each user based on required data rates and the computed average channel gains of sub-carriers/time slots for each user;
c) computing the number of sub-carriers/time slots to be allocated to each user based on the computed average numbers of bits of the sub-carriers/time slots for each user and allocating the sub-carriers/time slots to each user based on the computed average numbers of bits of the sub-carriers/time slots for each user and the computed number of sub-carriers/time slots to be allocated to each user;
d) selecting a modulation process to modulate data according to a magnitude of the sub-carrier/time slot allocated to each user; and
e) modulating data to be transmitted for each user through the selected modulation process, and transmitting said modulated data.
2. The method as recited in claim 1 , wherein the average channel gain of each user in the step a) is computed by using an equation as:
α
_
k
2
=
1
N
∑
n
=
1
N
α
k
,
n
2
,
for
k
=
1
…
K
wherein α k 2 is the average channel gain of sub-carrier for each user and α 2 k,n is the channel gain of sub-carrier/time slot for each user.
3. The method as recited in claim 1 , wherein the average number of bits for each user in the step b) is a solution of K+1 non-linear equations formulated by an equation as:
c
_
k
f
'
(
c
_
k
)
-
f
(
c
_
k
)
α
_
k
2
=
ɛ
,
for
k
=
1
,
…
,
K
∑
k
=
1
K
R
k
/
c
_
k
=
N
wherein c k is an average number of bits for each user, f(c) is a power to receive c bits data within a range of bit error rate, and R k is the total number of bits for each user.
4. The method as recited in claim 1 , wherein the number of sub-carriers/time slots in the step c) is computed by using an equation as:
n k =R k / c k , for k =1, . . . , K
wherein, n k is the number of allocated sub-carriers/time slots for each user.
5. The method as recited in claim 1 , wherein the allocation of sub-carrier/time slot in the step c) is an optimal solution of an equation as:
Minimize
P
i
-
∑
k
=
1
K
∑
n
=
1
N
r
k
,
n
ρ
k
,
n
Subject
to
∑
n
=
1
N
ρ
k
,
n
=
n
k
,
for
all
k
∑
k
=
1
K
ρ
k
,
n
=
1
,
for
all
n
wherein p k,n is a variable number which determines whether a K-th user uses an n-th sub-carrier and r k,n is a cost for the K-th user to use the n-th sub-carrier.
6. The method as recited in claim 5 , wherein the cost for the K-th user to use the n-th sub-carrier is determined by an equation as:
r k,n =ƒ( c k )/α 2 k,n , for k= 1, . . . , K and n= 1, . . . , N.
7. The method as recited in claim 5 , wherein a linear optimal solution is solved by applying a Vogel's method.
8. A computer readable recording medium for storing programs for executing a method for adaptively allocating resources in a communication system including a microprocessor by subsequently performing sub-carrier/time slot allocation and modulation selection processes, comprising the steps of:
a) computing average channel gains of sub-carriers/time slots for each user based on channel gains of sub-carriers/time slots for each user;
b) computing average numbers of bits of sub-carriers/time slots for each user based on required data rates and the computed average channel gains of sub-carriers/time slots for each user;
c) computing the number of sub-carriers/time slots to be allocated to each user based on the computed average numbers of bits of the sub-carriers/time slots for each user and allocating the sub-carriers/time slots to each user based on the computed average numbers of bits of the sub-carriers/time slots for each user and the computed number of sub-carriers/time slots to be allocated to each user;
d) selecting a modulation process to modulate data according to a magnitude of the sub-carrier/time slot allocated to each user; and
e) modulating data to be transmitted for each user through the selected modulation process, and transmitting said modulated data.