Apparatus and method for transmitting data using multiple antennas and beamforming
View Patent ↗Provided are an apparatus and method for transmitting data using multiple antennas and beamforming. The apparatus of the present invention comprises: a modulation unit which performs constellation mapping on input bits to generate modulated symbols; a pre-coding unit which multiplies a pre-coding matrix and the modulated symbols to generate pre-coded symbols; and a plurality of transmitting antennas for transmitting the pre-coded symbols. According to the present invention, a beam width is maintained constant, regardless of a radiation angle, thus preventing a loss of power caused by an angular spread and preventing the generation of shadow zone at a large radiation angle.
1. A transmission apparatus, comprising:
a modulation unit generating modulation symbols by performing constellation mapping on input bits;
a precoding unit generating precoded symbols by multiplying the modulation symbols by a precoding matrix;
a plurality of transmission antennas sending the precoded symbols, the plurality of transmission antennas divided into two antenna groups; and
a precoding matrix configuration unit controlling elements of the precoding matrix so that a specific user equipment receives, from the two antenna groups, signals having an identical phase on an identical plane,
wherein the transmission antennas of a first antenna group are arrayed at a first distance on a straight line, and the transmission antennas of a second antenna group are arrayed at the first distance on a line parallel to the transmission antennas of the first antenna group, and
wherein the first antenna group and the second antenna group are spaced apart from each other at a second distance.
2. The transmission apparatus of claim 1 , wherein the elements are mapped to the plurality of transmission antennas and comprise a phase component which determines phases of the modulation symbols.
3. The transmission apparatus of claim 2 , wherein the phase component is a function of an Angle of Departure (angle of departure) that is an angle formed by a path of the signals, transmitted from the plurality of transmission antennas to the specific user equipment, and the plurality of transmission antennas.
4. The transmission apparatus of claim 2 , wherein the phase component is a function using a value of the second distance as a parameter.
5. The transmission apparatus of claim 3 , wherein the precoding matrix configuration unit configures the precoding matrix like Equation below:
1
ⅇ
-
j
d
1
sin
θ
ⅇ
-
j
2
d
1
sin
θ
ⅇ
-
j3d
1
sin
θ
ⅇ
d
2
cos
θ
ⅇ
d
2
cos
θ
-
jd
1
sin
θ
ⅇ
d
2
cos
θ
-
j2d
1
sin
θ
ⅇ
d
2
cos
θ
-
j
3
d
1
sin
θ
wherein each of the first and the second antenna group comprises four transmission antennas, d 1 is the first distance, d 2 is the second distance, θ is the angle of departure, a first row to a fourth row of the precoding matrix are mapped to the first antenna group, and a fifth row to a eighth row of the precoding matrix are mapped to the second antenna group.
6. User equipment in a multiple antenna system, comprising:
reception antennas receiving precoded symbols from a base station based on a precoding matrix;
a de-precoding unit generating modulation symbols by multiplying the precoded symbols by an inverse precoding matrix; and
a demodulator demodulating the modulation symbols,
wherein the precoding matrix comprises a plurality of elements, and values of the plurality of elements are determined so that the user equipment receives, from two groups of transmission antennas, signals having an identical phase on an identical plane,
wherein a first group of transmission antennas are arrayed at a first distance on a straight line, and a second group of transmission antennas are arrayed at the first distance on a line parallel to the transmission antennas of the first antenna group, and
wherein the first group of transmission antennas and the second group of transmission antennas are spaced apart from each other at a second distance.
7. A transmission method, comprising the steps of:
generating modulation symbols by performing constellation mapping on input bits;
generating precoded symbols by multiplying the modulation symbols by a precoding matrix;
and sending the precoded symbols to user equipment using a plurality of transmission antennas,
wherein the plurality of transmission antennas is divided into two antenna groups, the transmission antennas of a first antenna group are arrayed at a first distance on a straight line, and the transmission antennas of a second antenna group are arrayed at the first distance on a line parallel to the transmission antennas of the first antenna group,
wherein the precoding matrix comprises elements having a number identical with a number of the plurality of transmission antennas,
wherein the elements are mapped to the plurality of transmission antennas in a one-to-one manner,
wherein each of the elements comprises a phase component determining phases of the modulation symbols, and
wherein the phase component determines the phase of the modulation symbol so that the user equipment receives signals, having an identical phase on an identical plane, from the two antenna groups.
8. A method of receiving signals in a multiple antenna system, comprising the steps of:
receiving precoded symbols from a base station based on a precoding matrix;
generating modulation symbols by multiplying the precoded symbols by an inverse precoding matrix; and
demodulating the modulation symbols,
wherein the precoding matrix comprises a plurality of elements, and values of the plurality of elements are determined so that user equipment receives signals, from two groups of transmission antennas, having an identical phase on an identical plane,
wherein a first group of transmission antennas are arrayed at a first distance on a straight line, and a second group of transmission antennas are arrayed at the first distance on a line parallel to the transmission antennas of the first antenna group, and
wherein the first group of transmission antennas and the second group of transmission antennas are spaced apart from each other at a second distance.