Transmitting/receiving apparatus and method for interleaver division multiple access system
Provided is a transmitting/receiving apparatus and method for an IDMA system. The receiving apparatus includes a channel estimator, an estimator, and a determiner. The channel estimator estimates a channel using a multi-user signal received through at least one RX antenna. The estimator estimates the noise power and the signal power for each transmission layer of each user by using the estimated channel value from the channel estimator. The determiner determines the number of transmission layers for each user and an MCS level for each transmission layer by using the signal power and the noise power estimated by the estimator.
1. A receiving apparatus for an Interleaver Division Multiple Access (IDMA) system, the apparatus comprising:
a channel estimator for estimating a channel using a multi-user signal received through at least one RX antenna;
an estimator for estimating the noise power and the signal power for each transmission layer of each user by using the estimated channel value from the channel estimator; and
a determiner for determining the number of transmission layers for each user and an Modulation and Coding Scheme (MCS) level for each transmission layer of each user by using the signal power and the noise power estimated by the estimator,
wherein the multi-user signal includes multiple user signals being interleaved in different interleaving schemes with each other,
wherein the determiner comprises a preliminary determiner for preliminarily determining the number of transmission layers and the MCS level for each transmission layer on a user-by-user basis on the basis of a Signal-to-Noise Ratio (SNR) with respect to each of users that gain multiple access in different interleaving schemes, and
wherein the preliminary determiner calculates a data rate R t for selection of t transmission layers by using Equation (1) or Equation (2) depending on a structure of a corresponding transmitter
R
t
=
t
·
MCS
(
∑
l
=
1
t
P
k
,
l
/
t
σ
2
)
(
1
)
R
t
=
∑
l
=
1
t
MCS
(
P
k
,
l
t
σ
2
)
(
2
)
where P k,l denotes the signal power for the l th transmission layer of the k th user, σ 2 denotes noise power, and MCS( )denotes a function for calculating a data rate depending on the MCS level.
2. The receiving apparatus of claim 1 , wherein the determiner further comprises:
a calculator for calculating a total receive power on the basis of the determined transmission layer numbers for the users;
an adjuster for calculating a Signal-to-Interference plus Noise Ratio (SINR) for each transmission layer of each user by using the calculated total RX power to, and adjusting the preliminary MCS level by comparing the calculated SINR value with a threshold value; and
a feedback information generator for generating feedback information by using a final transmission layer number for each user and the MCS level for each transmission layer, and transmitting the generated feedback information to the corresponding user.
3. The receiving apparatus of claim 1 , wherein the preliminary determiner arranges the signal powers for the respective transmission layers in descending order of strength,
calculates the data rate for each of the transmission layers while adding the arranged transmission layers one by one,
compares a previous data rate for selection of (t-1) transmission layers with a current data rate for selection oft transmission layers,
allows (t-1) transmission layers for the corresponding user if the current data rate is smaller than the previous data rate, and
determines the preliminary MCS level for each of the allowed transmission layers.
4. The receiving apparatus of claim 2 , wherein the calculator calculates the total RX power P r as the following equation:
P
r
=
σ
2
+
∑
k
=
1
K
1
t
k
∑
l
=
1
t
k
P
k
,
l
where σ 2 denotes noise power, k denotes a user index, t k denotes the number of transmission layers for the k th user, and P k,l denotes the signal power for the l th transmission layer of the k th user.
5. The receiving apparatus of claim 2 , wherein the adjuster calculates the SINR for the l th transmission layer of the k th user as the following equation:
SINR
k
,
l
_
=
P
k
,
l
/
t
k
P
r
-
P
k
,
l
/
t
k
where P r denotes the total RX power, t k denotes the number of transmission layers for the k th user, and P k,l denotes the signal power for the l th transmission layer of the k th user.
6. The receiving apparatus of claim 2 , wherein the threshold value is determined by the SINR for the preliminarily-determined MCS level.
7. The receiving apparatus of claim 1 , further comprising a receiver unit for detecting and decoding the received multi-user signal in an IDMA scheme.
8. The receiving apparatus of claim 1 , wherein the feedback information comprises at least one of the number of transmission layers, a modulation order and a coding rate for each transmission layer, and a weight matrix for precoding.
9. A method for an operation of a receiver in an Interleaver Division Multiple Access (IDMA) system, the method comprising:
estimating, by the receiver, a channel using a multi-user signal received through at least one RX antenna;
estimating, by the receiver, the noise power and the signal power for each transmission layer of each user by using the estimated channel value; and
determining, by the receiver, the number of transmission layers for each user and an Modulation and Coding Scheme (MCS) level for each transmission layer of each user by using the estimated signal power and the estimated noise power,
wherein the multi-user signal includes multiple user signals being interleaved in different interleaving schemes with each other,
wherein the determining comprises preliminarily determining the number of transmission layers and the MCS level for each transmission layer on a user-by-user basis on the basis of a Signal-to-Noise Ratio (SNR) with respect to each of users that gain multiple access in different interleaving schemes,
wherein the preliminary determining comprises:
arranging the signal powers for the respective transmission layers in descending order of strength;
calculating a data rate for each of the transmission layer numbers while adding the arranged transmission layers one by one;
comparing a previous data rate for selection of (t-1) transmission layers with a current data rate for selection oft transmission layers;
allowing (t-1) transmission layers for the corresponding user if the current data rate is smaller than the previous data rate; and
determining the preliminary MCS level for each of the allowed transmission layers, and
wherein when the number of transmission layers is t, a data rate R t is calculated using Equation (1) or Equation (2) depending on a structure of a corresponding transmitter
R
t
=
t
·
MCS
(
∑
l
=
1
t
P
k
,
l
/
t
σ
2
)
(
1
)
R
t
=
∑
l
=
1
t
MCS
(
P
k
,
l
t
σ
2
)
(
2
)
where P k,l denotes the signal power for the l th transmission layer of the k th user, σ 2 denotes noise power, and MCS( )denotes a function for calculating a data rate depending on the MCS level.
10. The method of claim 9 , wherein the determining further comprises:
calculating a total receive power on the basis of the determined transmission layer numbers for the users;
calculating a Signal-to-Interference plus Noise Ratio (SINR) for each transmission layer of each user by using the calculated total RX power to, and adjusting the preliminary MCS level by comparing the calculated SINR value with a threshold value;
generating feedback information by using a final transmission layer number for each user and the MCS level for each transmission layer; and
transmitting the generated feedback information to the corresponding user.
11. The method of claim 10 , wherein the total RX power Pr is calculated as the following equation:
P
r
=
σ
2
+
∑
k
=
1
K
1
t
k
∑
l
=
1
t
k
P
k
,
l
where σ 2 denotes noise power, k denotes a user index, t k denotes the number of transmission layers for the k th user, and P k,l denotes the signal power for the l th transmission layer of the k th user.
12. The method of claim 10 , wherein the SINR for the l th transmission layer of the k th user is calculated as the following equation:
SINR
k
,
l
_
=
P
k
,
l
/
t
k
P
r
-
P
k
,
l
/
t
k
where P r denotes the total RX power, t k denotes the number of transmission layers for the k th user, and P k,l denotes the signal power for the l th transmission layer of the k th user.
13. The method of claim 10 , wherein the threshold value is determined by the SINR for the preliminarily-determined MCS level.
14. The method of claim 9 , further comprising restoring information data of each user by detecting and decoding the received multi-user signal in an IDMA scheme.
15. The method of claim 9 , wherein the feedback information comprises at least one of the number of transmission layers, a modulation order and a coding rate for each transmission layer, and a weight matrix for precoding.