KR101284935B1 - Outage-based robust beam design method for mimo interference channel with channel uncertainty - Google Patents

Outage-based robust beam design method for mimo interference channel with channel uncertainty Download PDF

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KR101284935B1
KR101284935B1 KR1020120066127A KR20120066127A KR101284935B1 KR 101284935 B1 KR101284935 B1 KR 101284935B1 KR 1020120066127 A KR1020120066127 A KR 1020120066127A KR 20120066127 A KR20120066127 A KR 20120066127A KR 101284935 B1 KR101284935 B1 KR 101284935B1
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transmission
equation
robust
outage
design method
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Korean (ko)
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성영철
박주호
김동건
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한국과학기술원
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/0413—MIMO systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0617—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal for beam forming

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  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Radio Transmission System (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

PURPOSE: An outage based robust beam design method in a multiple-input multiple-output (MIMO) interference channel is provided to obtain outage probability of a MIMO channel and to maximize a transmission rate within given outage probability restriction using the outage probability. CONSTITUTION: An arbitrary transception beam with respect to given channel information and maximum allowable outage probability is set (210). The maximum rate tuple is obtained by message within the given maximum allowable outage probability with respect to the transception beam (220). A transmission beam with respect to the rate tuple and reception beam is designed (230). A reception beam is designed using the rate tuple and transmission beam (240). Each of the transmission beam and reception beam has unit length. [Reference numerals] (210) Select a random transception beam; (220) Obtain a maximum rate tuple of the beam within a maximum permittable outage rate range for each message; (230) Design a transmission beam regarding the rate tuple and a reception beam; (240) Design the reception beam using the rate tuple and the designed transmission beam; (AA) Start; (BB) End

Description

Robust beam design method based on OPTAABE in multi-input multi-output interference channel

The present invention relates to an outage-based robust beam design method in a multiple-input multiple-output (MIMO) interference channel.

Many methods have been proposed to effectively remove interference in high-interference mobile communication systems, and the importance of interference management technology has recently become more important as performance degradation caused by interference has become a serious problem in next-generation mobile communication systems. have. In particular, when a transceiver has multiple antennas, a method of effectively controlling interference by using an appropriate transmit / receive beam is particularly useful and widely studied.

Recently, there is an interference alignment technique as a representative beam design technique that can effectively control interference by using a transmission / reception beam. The interference aligning technique is a method in which each transmitter knows all channel information, so that the transmitter forms proper beamforming so that the space where interference enters and the space where a desired signal is located at each receiver is linearly independent. By using the interference-aligned transmission beam, the signal space occupied by the interference signal and the desired signal can be linearly independent, thereby obtaining a signal from which interference is removed even through a simple linear reception beam. However, interference alignment is useful at high signal-to-noise ratios, and since the edges of the cell where the actual interference is high have low signal-to-noise ratios, the interference alignment technique is not suitable for controlling inter-cell interference in real wireless communication systems. Therefore, techniques for ensuring performance at low signal-to-noise ratios in interfering channels have been studied.

The beam-forming method for achieving good performance at low signal-to-noise ratio is the `max-SINR 'algorithm. In this method, once a transmission beam is given, the reception beam is designed with a whitened matched filter that matches the transmission beam, and then the transmission beam is received using the channel's reciprocity to design the transmission beam. Design with white matched filter. This method is not optimal in theory, but performs well on real systems.

Since the actual beam design method is applied to a real mobile communication system in which the transmitter and the receiver do not know the channel information perfectly, the present invention assumes that the transceiver knows only a part of the channel and has an error in the channel estimation value in the MIMO interference channel. do. In such a situation, information cannot be sent at a desired data rate due to channel estimation error. Such an event is called an outage. The present invention proposes a transmission / reception beam design technique capable of obtaining an outage probability of a MIMO interference channel in the above situation and maximizing a transmission rate within a given outage probability constraint.

Robust beam design method, based on outage in MIMO interference channel, given channel information

Figure 112012049049823-pat00001
Transmit / receive beams for and maximum allowable outage probability ε
Figure 112012049049823-pat00002
Setting up; Maximum rate tuple within given maximum allowed outage probability for transmit and receive beams
Figure 112012049049823-pat00003
Obtaining each message; Rate Tuple and Receive Beam
Figure 112012049049823-pat00004
About the transmission beam
Figure 112012049049823-pat00005
Designing a; And Rate Tuple and Transmit Beam
Figure 112012049049823-pat00006
Receive beam using
Figure 112012049049823-pat00007
There is provided a robust beam design method comprising the step of designing.

In one side, the transmission beam

Figure 112012049049823-pat00008
And receive
Figure 112012049049823-pat00009
The beam has a unit length.

In another aspect, Rate Tuple and Receive Beam

Figure 112012049049823-pat00010
About the transmission beam
Figure 112012049049823-pat00011
In the design stage, the transmission beam is solved so that the maximum value among the outage probabilities of each message is minimized by solving the optimization problem shown in
Figure 112012049049823-pat00012
Design it.

Equation:

Figure 112012049049823-pat00013

In another aspect, a transmission beam

Figure 112012049049823-pat00014
Is optimized one by one for each message, but all other transmission beams are fixed except for the transmission beam that performs the optimization, and the optimization is performed sequentially from the first transmission beam of the first transmitter to the last transmission beam of the last transmitter. Optimization) technique.

In another aspect, the iterative optimization technique is repeated to iterate repeatedly until all transmit beams converge to a critical point.

Figure 112012049049823-pat00015
.

In another aspect, the Rate Tuple and the transmit beam

Figure 112012049049823-pat00016
Receive beam using
Figure 112012049049823-pat00017
In the design phase, each rate tuple and transmit beam
Figure 112012049049823-pat00018
Receive beam that minimizes the probability of outage for each message
Figure 112012049049823-pat00019
It is obtained by applying to the following equation.

Equation:

Figure 112012049049823-pat00020

In another aspect, the Rate Tuple and the transmit beam

Figure 112012049049823-pat00021
Receive beam using
Figure 112012049049823-pat00022
Designing the step, the receiving beam
Figure 112012049049823-pat00023
Is distributed to each message in each receiver.

In yet another aspect, a robust beam design method includes a maximum rate tuple within a maximum allowable outage probability given for a transmit / receive beam for a transmit / receive beam.

Figure 112012049049823-pat00024
Obtaining each message; Rate Tuple and Receive Beam
Figure 112012049049823-pat00025
About the transmission beam
Figure 112012049049823-pat00026
Designing a; And Rate Tuple and Transmit Beam
Figure 112012049049823-pat00027
Receive beam using
Figure 112012049049823-pat00028
Repeating the step of designing the convergence to the critical point
Figure 112012049049823-pat00029
And receive beam
Figure 112012049049823-pat00030
Design it.

In another aspect, the outage probability at a given transmit / receive beam and rate is obtained by the following equation.

Equation:

Figure 112012049049823-pat00031

Since the channel estimation error model commonly used in the real wireless communication system is used, an algorithm suitable for real situation has been developed. Using the proposed transmission / reception beam design method of the present invention, the total data rate that can be transmitted within a given outage probability may be increased in comparison with the conventional beam design method that assumes perfect channel information in a real mobile communication system having channel uncertainty. Can be.

1 illustrates a system model of a MIMO interference channel in an embodiment of the invention.
2 is a flowchart illustrating each step of the beam design method according to the embodiment of the present invention.
3 is a graph showing the total data rate obtained by the simulation of the proposed beam design method in the embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The present invention

Figure 112012049049823-pat00032
Base stations and base stations to which information is transmitted
Figure 112012049049823-pat00033
There are two receiving terminals, and each base station
Figure 112012049049823-pat00034
Two transmitting antennas, and the terminal
Figure 112012049049823-pat00035
The assumption is made with two receiving antennas. Each base station attempts to transmit information to a terminal paired with itself in pairs with one other terminal, but each terminal receives an interference signal from another base station. Such a channel model can be viewed as a multiple input multiple output (MIMO) interference channel (IC). The channel model of FIG. 1 represents such a MIMO interference channel,
Figure 112012049049823-pat00036
The phosphorus interference channel is shown. The transmitting end 110 has three base stations, the receiving end 120 has three terminals, respectively, and the base station and the terminal each have a base station.
Figure 112012049049823-pat00037
Dog
Figure 112012049049823-pat00038
Communication model with two antennas.

In the following description, an outage event that prevents communication at a desired transmission rate due to channel estimation error is defined. First, the terminal in the MIMO interference channel

Figure 112012049049823-pat00039
(Base station
Figure 112012049049823-pat00040
The signal received by the terminal) can be written as in Equation 1. Hereinafter, the base station is used interchangeably with the transmitter (end) and the terminal (end).

Figure 112012049049823-pat00041

here,

Figure 112012049049823-pat00042
Transmitter
Figure 112012049049823-pat00043
And receiver
Figure 112012049049823-pat00044
Channel between
Figure 112012049049823-pat00045
Is a matrix
Figure 112012049049823-pat00046
Is the size
Figure 112012049049823-pat00047
In the transmission beamforming matrix, assume that each column has a size of 1 (that is,
Figure 112012049049823-pat00048
,
Figure 112012049049823-pat00049
) Also,
Figure 112012049049823-pat00050
Transmitter
Figure 112012049049823-pat00051
Is the size
Figure 112012049049823-pat00052
Means the transmit image vector. Message vector
Figure 112012049049823-pat00053
And thermal noise vector
Figure 112012049049823-pat00054
Are each made up of a circular symmetric complex normal distribution,
Figure 112012049049823-pat00055
Wow
Figure 112012049049823-pat00056
Can be assumed to follow. In other words, any probability vector
Figure 112012049049823-pat00057
end
Figure 112012049049823-pat00058
If this is the probability vector
Figure 112012049049823-pat00059
Is a vector with a complex normal probability, meaning that the mean is μ and the covariance is R.

In the present invention, it is assumed that the transmitter and the receiver know only the estimated value for the actual channel value, and there is a relationship as shown in Equation 2 between the actual channel and the estimated channel.

Figure 112012049049823-pat00060

all

Figure 112012049049823-pat00061
(At this time,
Figure 112012049049823-pat00062
)

here,

Figure 112012049049823-pat00063
The The actual channel is unknown to the transceiver,
Figure 112012049049823-pat00064
Is incomplete channel information that the transceiver estimates.
Figure 112012049049823-pat00065
Denotes an error between the actual channel and the estimated channel, and assumes that the error matrix follows the Kronecker model as shown in Equation 3 below to consider the correlation of the transmitting and receiving antennas.

Figure 112012049049823-pat00066

Figure 112012049049823-pat00067
Wow
Figure 112012049049823-pat00068
Are matrices representing the correlation between the receiving antenna and the transmitting antenna, respectively.
Figure 112012049049823-pat00069
Is any positive constant
Figure 112012049049823-pat00070
About
Figure 112012049049823-pat00071
Is a probability matrix. Therefore, the channel estimation error matrix represented by Equation 3
Figure 112012049049823-pat00072
Also follows the circular symmetric normal probability and averaged, and the covariance
Figure 112012049049823-pat00073
, In other words
Figure 112012049049823-pat00074
to be.
Figure 112012049049823-pat00075
Is a value related to the accuracy of the channel estimation,
Figure 112012049049823-pat00076
A smaller value means a smaller channel estimation error, and a larger value may mean that the difference between the estimated channel and the actual channel is large. Also, channel estimation error
Figure 112012049049823-pat00077
Different transceiver pairs
Figure 112012049049823-pat00078
Is independent. Two variables are defined in Equation 4 to represent the accuracy of the channel estimation and the strength of the received signal.

Figure 112012049049823-pat00079

Figure 112012049049823-pat00080
Denotes the level of channel estimation as a 'channel K-factor' defined as the ratio of the magnitude of the estimated channel to the magnitude of the channel estimation error. This means that if the channel K-factor is large, the estimate is accurate, and if it is small, the opposite is true. Also,
Figure 112012049049823-pat00081
Denotes a signal-to-noise ratio (SNR) of the received signal. Hereinafter, the channel information known to the transceiver
Figure 112012049049823-pat00082
To indicate

receiving set

Figure 112012049049823-pat00083
Is being delivered to myself
Figure 112012049049823-pat00084
Messages out of
Figure 112012049049823-pat00085
Receive beam with unit length to restore
Figure 112012049049823-pat00086
Received on
Figure 112012049049823-pat00087
The message sent can be estimated through Equation 5.

Figure 112012049049823-pat00088

The transmit and receive beamforming matrix is channel information known to the transceiver.

Figure 112012049049823-pat00089
Assume that the design is based on. Therefore, all the contents covered by the present invention may include an interference alignment beam or other known linear transmit / receive beams. In the reception model as described above, a signal-to-interference plus noise ratio (SINR) may be expressed as in Equation 6.

Figure 112012049049823-pat00090

The denominator on the right side shows interference due to channel estimation errors, interference due to signals to other users, and noise and thermal noise caused by other messages, respectively. Channel estimation error matrix

Figure 112012049049823-pat00091
Since this is a random variable, the SINR value shown in Equation 6 is also given
Figure 112012049049823-pat00092
Wow
Figure 112012049049823-pat00093
For random variables.

Thus, the receiver

Figure 112012049049823-pat00094
Message from
Figure 112012049049823-pat00095
Outage occurs when the data rate determined by the SINR represented by Equation 6 becomes smaller than the target data rate. Thus receiver
Figure 112012049049823-pat00096
Message from
Figure 112012049049823-pat00097
The probability of occurrence of an outage event can be written as in Equation 7, and by rearranging the SINR equation in Equation 6, the outage event can be obtained as in Equation 8.

Figure 112012049049823-pat00098

Figure 112012049049823-pat00099

Figure 112012049049823-pat00100
Follows a circular symmetric complex normal probability,
Figure 112012049049823-pat00101
Figure 112012049049823-pat00102
Also a circular symmetric complex normal random variable. Therefore, the left side of Equation 8 is a quadratic form of normal random variables whose mean is not zero. The outage event of Equation 8 can be expressed more simply as shown in Equation 9 by using a vector.

Figure 112012049049823-pat00103

here,

Figure 112012049049823-pat00104
to be. vector
Figure 112012049049823-pat00105
Average of
Figure 112012049049823-pat00106
Each element of
Figure 112012049049823-pat00107
Wow
Figure 112012049049823-pat00108
Is given by Equation 10 below.

Figure 112012049049823-pat00109

And,

Figure 112012049049823-pat00110
The covariance matrix of is a block diagonal matrix,
Figure 112012049049823-pat00111
Different
Figure 112012049049823-pat00112
Because independence. In other words,
Figure 112012049049823-pat00113
Of the covariance matrix
Figure 112012049049823-pat00114
,
Figure 112012049049823-pat00115
Figure 112012049049823-pat00116
Given by
Figure 112012049049823-pat00117
of
Figure 112012049049823-pat00118
Is each
Figure 112012049049823-pat00119
(
Figure 112012049049823-pat00120
In Equation 11).

Figure 112012049049823-pat00121

As described above, an error exists between a real channel and a known channel, and if the error is given as a normal distribution, the target rate may not be sent no matter how small the target rate is. Hereinafter, when an outage event is represented as a quadratic form of a complex normal probability in which the mean is not 0, in the MIMO interference channel,

Figure 112012049049823-pat00122
Message of
Figure 112012049049823-pat00123
The probability of occurrence of an outage event can be found at.

There is an error between channel information such as Equation 2 and Equation 3 and actual channel information, and the transmission / reception beamforming matrix

Figure 112012049049823-pat00124
Wow
Figure 112012049049823-pat00125
Receiver is given
Figure 112012049049823-pat00126
Message of
Figure 112012049049823-pat00127
Target rate
Figure 112012049049823-pat00128
The probability that Outage occurs because it does not satisfy is equal to Equation 12.

Figure 112012049049823-pat00129

here,

Figure 112012049049823-pat00130
Is the same as Equation 8,
Figure 112012049049823-pat00131
Is the covariance matrix shown in equation (11).
Figure 112012049049823-pat00132
Different eigenvalues.
Figure 112012049049823-pat00133
Is eigenvalue
Figure 112012049049823-pat00134
Is the multiplicity of
Figure 112012049049823-pat00135
Is an element of the vector shown in Equation 13 below.
Figure 112012049049823-pat00136
of
Figure 112012049049823-pat00137
The eigenvalue of the first eigenvector times the mean vector
Figure 112012049049823-pat00138
The square root of.

Figure 112012049049823-pat00139

Figure 112012049049823-pat00140
The
Figure 112012049049823-pat00141
of
Figure 112012049049823-pat00142
Second element,
Figure 112012049049823-pat00143
Is defined as

Figure 112012049049823-pat00144

here,

Figure 112012049049823-pat00145
The
Figure 112012049049823-pat00146
Means the nth derivative of.

Theorems ranging from Equations 12 to 14 can be applied to provide outage probabilities in various cases.

First, the outage probability of knowing a few of the channels between the receiver and the transmitter, i.e.

Figure 112012049049823-pat00147
in
Figure 112012049049823-pat00148
Is,
Figure 112012049049823-pat00149
Receiver
Figure 112012049049823-pat00150
Message of
Figure 112012049049823-pat00151
Target rate
Figure 112012049049823-pat00152
The probability of occurrence of Outage because it does not satisfy is equal to Equation 15.

Figure 112012049049823-pat00153

Figure 112012049049823-pat00154

Equation 15 refers to the value of Equation 16,

Figure 112012049049823-pat00155
Denote different eigenvalues of the covariance matrix shown in equation (11). If you know the exact value of some channels, the number of random variables in the SINR equation
Figure 112012049049823-pat00156
Reduced to dog Thus, probability vector
Figure 112012049049823-pat00157
The size of
Figure 112012049049823-pat00158
Becomes the covariance matrix
Figure 112012049049823-pat00159
Size
Figure 112012049049823-pat00160
.

In another case, each receiver knows the channel to the transmitter that conveys information to it (i.e.,

Figure 112012049049823-pat00161
A), send and receive beam
Figure 112012049049823-pat00162
Receiver, when designed and used as an interference alignment beam
Figure 112012049049823-pat00163
Message of
Figure 112012049049823-pat00164
Target rate
Figure 112012049049823-pat00165
The probability of occurrence of Outage because it does not satisfy is equal to Equation 17.

Figure 112012049049823-pat00166

This theorem shows that using an interference aligned beam eliminates the need to calculate infinite series when calculating outage probabilities.

And in the third case, the number of messages sent by each transmitter is one (i.e.

Figure 112012049049823-pat00167
Covariance matrix
Figure 112012049049823-pat00168
When the eigenvalues of are all different, the receiver
Figure 112012049049823-pat00169
The outage probability at is given by Equation 18.

Figure 112012049049823-pat00170

And finally,

Figure 112012049049823-pat00171
If there is no correlation between the antennas (
Figure 112012049049823-pat00172
), Outage odds
Figure 112012049049823-pat00173
Transmit and receive beam vector
Figure 112012049049823-pat00174
In this case, the probability of outage may be expressed by Equation 19.

Figure 112012049049823-pat00175

here,

Figure 112012049049823-pat00176
ego,
Figure 112012049049823-pat00177
to be. Especially,
Figure 112012049049823-pat00178
According to equation (10)
Figure 112012049049823-pat00179
It can be represented by a combination.

Hereinafter, the upper limit of the probability of outage is obtained using the Chernoff upper bound. The reason why the Chernoff Bound is used is that the specific value of the outage probability described above can be calculated numerically, but since it is not easy to deal with the infinite series, it is useful to obtain the upper limit of the probability.

Using Markov Inequality, the upper limit of the probability of outage can be calculated as in Equation 20.

Figure 112012049049823-pat00180

Figure 112012049049823-pat00181
The moment generating function of is (moment generating function)
Figure 112012049049823-pat00182
)

Figure 112012049049823-pat00183

At this time,

Figure 112012049049823-pat00184
,
Figure 112012049049823-pat00185
ego,
Figure 112012049049823-pat00186
to be. Therefore, the upper limit of the outage probability can be obtained as follows.

Figure 112012049049823-pat00187

random

Figure 112012049049823-pat00188
By selecting the appropriate s at, the upper limit of the probability of outage can be calculated relatively simply.

In the embodiment of the present invention, FIG. 2 is a flowchart illustrating a robust beam design method based on outage in a MIMO interference channel. Robust beam design method given channel information

Figure 112012049049823-pat00189
Transmit / receive beams for and maximum allowable outage probability ε
Figure 112012049049823-pat00190
Setting 210; Maximum rate tuple within given maximum allowed outage probability for transmit and receive beams
Figure 112012049049823-pat00191
Obtaining 220 for each message; Rate Tuple and Receive Beam
Figure 112012049049823-pat00192
About the transmission beam
Figure 112012049049823-pat00193
Designing 230; And Rate Tuple and Transmit Beam
Figure 112012049049823-pat00194
Receive beam using
Figure 112012049049823-pat00195
It may include the step 240 of designing. Transmission beam designed through the present invention
Figure 112012049049823-pat00196
And receive beam
Figure 112012049049823-pat00197
Is proposed to have a unit length, and when the maximum probability of outage is ε for each message, a transmission / reception beam capable of maximizing the total transmission amount is obtained.

The transmission / reception beam design problem for maximizing the total transmission rate within the maximum allowable outage probability considered in the present invention is represented by Equation 23.

Figure 112012049049823-pat00198

In order to solve this, step 240 may be repeated in step 220.

Step 220 is a given transmit and receive beam

Figure 112012049049823-pat00199
Rate Tuple that maximizes the objective function while satisfying the outage constraint
Figure 112012049049823-pat00200
Can be obtained.
Figure 112012049049823-pat00201
Since the larger the outage probability is, the larger the transmission probability becomes.
Figure 112012049049823-pat00202
Rate Tuple can be obtained for each message.

In addition, step 230 is a rate tuple obtained in step 220

Figure 112012049049823-pat00203
And the received beam given in step 210
Figure 112012049049823-pat00204
About the transmission beam
Figure 112012049049823-pat00205
In this case, since each transmission beam affects the outage probability of all receivers, the transmission beam is solved by solving the optimization problem shown in Equation 24 so that the maximum value of the outage probability of each message is the minimum.
Figure 112012049049823-pat00206
Therefore, the outage probability of all messages is lowered.

Therefore, the outage probability of all messages is lowered.

Figure 112012049049823-pat00207

Transmission beam

Figure 112012049049823-pat00208
silver
Figure 112012049049823-pat00209
Since it is difficult to design two transmission beams at the same time, it is optimized for each message one by one, but all other transmission beams are fixed except for the transmission beam that performs the optimization, and the first transmission beam of the first transmitter and the last transmission beam of the last transmitter are fixed. Iterative optimization technique is used to perform optimization in order. This iterative optimization technique is repeated to repeat all transmission beams until they converge to a critical point.
Figure 112012049049823-pat00210
Can be obtained.

In step 240, the rate tuple and the transmission beam obtained in step 230

Figure 112012049049823-pat00211
Receive beam that minimizes the probability of outage for each message
Figure 112012049049823-pat00212
As to obtain, it can be obtained by applying to the following equation (25).

Figure 112012049049823-pat00213

This step 240 is the reception beam

Figure 112012049049823-pat00214
It can be obtained for each message in each receiver and distributed to each receiver.

In the robust beam design method, it is possible to design a transmission / reception beam that maximizes the total transmission rate within a given outage probability by repeating the process of step 240 until it converges to a threshold point in step 220.

Here, the outage probability ε according to the transmission / reception beam and the transmission rate, which are important criteria in the present invention, are shown in Equation 12, Equation 15, Equation 18, Equation 19, and Equation 22 according to the system situation. One of the Outage probability equations of can be applied.

The graph shown in FIG. 3 is a simulation of the robust beam design method proposed by the present invention and shows a total data rate graph.

Into the simulation environment

Figure 112012049049823-pat00215
,
Figure 112012049049823-pat00216
,
Figure 112012049049823-pat00217
ego,
Figure 112012049049823-pat00218
In this case, the transmission rate is improved compared to the known max-SINR method and the IIA method. In particular, when the SNR is low, the transmission rate is significantly improved. .

The method according to the embodiment may be embodied in the form of program instructions that can be executed by various computer means and recorded in a computer readable medium. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. The program instructions recorded on the media may be those specially designed and constructed for the purposes of the embodiments, or they may be of the kind well-known and available to those having skill in the computer software arts. Examples of the computer-readable recording medium include magnetic media such as a hard disk, a floppy disk and a magnetic tape, optical media such as CD-ROM and DVD, magnetic disks such as a floppy disk, - Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. For example, it is to be understood that the techniques described may be performed in a different order than the described methods, and / or that components of the described systems, structures, devices, circuits, Lt; / RTI > or equivalents thereof, the appropriate results may be achieved.

Therefore, other implementations, other embodiments, and equivalents to the claims are also within the scope of the following claims.

110: base station, transmitter
120: terminal, receiver

Claims (12)

In a robust beam design method,
Outage based on MIMO interference channel,
Given channel information
Figure 112012049049823-pat00219
Transmit / receive beams for and maximum allowable outage probability ε
Figure 112012049049823-pat00220
Setting up;
Maximum rate tuple within the maximum allowable outage probability given for the transmit and receive beams
Figure 112012049049823-pat00221
Obtaining each message;
The Rate Tuple and the Receive Beam
Figure 112012049049823-pat00222
About the transmission beam
Figure 112012049049823-pat00223
Designing a; And
The rate tuple and the transmit beam
Figure 112012049049823-pat00224
Receive beam using
Figure 112012049049823-pat00225
Steps to design
Robust beam design method comprising a. The method of claim 1,
The transmit beam
Figure 112012049049823-pat00226
And the receiving beam
Figure 112012049049823-pat00227
Having unit length
Robust beam design method characterized in that. The method of claim 1,
The Rate Tuple and the Receive Beam
Figure 112012049049823-pat00228
About the transmission beam
Figure 112012049049823-pat00229
In the step of designing, the transmission problem is solved by solving the optimization problem shown in the following equation and the maximum value among the outage probabilities of each message is minimized.
Figure 112012049049823-pat00230
To design
Robust beam design method characterized in that.
Equation:
Figure 112012049049823-pat00231
 The method of claim 3,
The transmit beam
Figure 112012049049823-pat00232
Is optimized one by one for each message, but all other transmission beams except for the transmission beam to be fixed are fixed, and iterative optimization is performed sequentially from the first transmission beam of the first transmitter to the last transmission beam of the last transmitter ( Using the Alternating Optimization technique,
The iterative optimization technique is repeated to repeat the transmission beam until all transmission beams converge to a critical point.
Figure 112012049049823-pat00233
To save
Robust beam design method characterized in that. The method of claim 1,
The rate tuple and the transmit beam
Figure 112012049049823-pat00234
Receive beam using
Figure 112012049049823-pat00235
In the design phase,
The rate tuple and the transmit beam
Figure 112012049049823-pat00236
A reception beam for minimizing an outage probability for each message
Figure 112012049049823-pat00237
Finding by applying to the following equation
Robust beam design method characterized in that.
Equation:
Figure 112012049049823-pat00238
 The method of claim 5,
The rate tuple and the transmit beam
Figure 112012049049823-pat00239
Receive beam using
Figure 112012049049823-pat00240
Designing step, the receive beam
Figure 112012049049823-pat00241
To perform a distributed operation for each message in each receiver
Robust beam design method characterized in that. The method of claim 1,
The robust beam design method
Maximum rate tuple within the maximum allowable outage probability given for the transmit and receive beams
Figure 112012049049823-pat00242
Obtaining each message;
The Rate Tuple and the Receive Beam
Figure 112012049049823-pat00243
About the transmission beam
Figure 112012049049823-pat00244
Designing a; And
The rate tuple and the transmit beam
Figure 112012049049823-pat00245
Receive beam using
Figure 112012049049823-pat00246
Steps to design
Repeat to converge to a threshold
Figure 112012049049823-pat00247
And the receiving beam
Figure 112012049049823-pat00248
To design
Robust beam design method characterized in that. The method of claim 1,
The outage probability of the transmission beam and the reception beam is obtained by the following equation.
Robust beam design method characterized in that.
Equation:
Figure 112012049049823-pat00249
 The method of claim 1,
The outage probability of the transmission beam and the reception beam is obtained by the following equation.
Robust beam design method characterized in that.
Equation:
Figure 112012049049823-pat00250
 The method of claim 1,
The outage probability of the transmission beam and the reception beam is obtained by the following equation.
Robust beam design method characterized in that.
Equation:
Figure 112012049049823-pat00251
 The method of claim 1,
The outage probability of the transmission beam and the reception beam is obtained by the following equation.
Robust beam design method characterized in that.
Equation:
Figure 112012049049823-pat00252
 The method of claim 1,
The outage probability of the transmission beam and the reception beam is obtained by the following equation.
Robust beam design method characterized in that.
Equation:
Figure 112012049049823-pat00253
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11252045B1 (en) 2021-10-18 2022-02-15 King Abdulaziz University Processing blind beamforming for multi-user multiple-input multiple-output (MU-MIMO) systems

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090221241A1 (en) 2006-02-22 2009-09-03 Koninklijke Philips Electronics, N.V. System, apparatus, and method for asymmetrical beamforming with equal-power transmissions

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090221241A1 (en) 2006-02-22 2009-09-03 Koninklijke Philips Electronics, N.V. System, apparatus, and method for asymmetrical beamforming with equal-power transmissions

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11252045B1 (en) 2021-10-18 2022-02-15 King Abdulaziz University Processing blind beamforming for multi-user multiple-input multiple-output (MU-MIMO) systems

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