KR101294105B1 - Receiver and decoding method applying the same - Google Patents

Abstract

A receiver and a decoding method applied thereto are provided. The receiver is capable of grouping a plurality of symbols included in received signals received from a plurality of transmitters, and decoding the grouped received signals by partial interface cancellation (PIC), thereby providing a high code rate and a low It is possible to implement a block-by-block transmission technique with complexity and low transmission time.

Description

Receiver and decoding method applied thereto {Receiver and decoding method applying the same}

The present invention relates to a receiver and a decoding method applied thereto, and more particularly, to a receiver using Partial Interference Cancellation (PIC) group decoding and a decoding method applied thereto.

As mobile usage increases, users want to be able to send and receive data faster. Accordingly, wireless communication technology is rapidly developing in recent years, and data rate, battery life, and network connectivity have been greatly improved with respect to wireless communication. With the advent of the YouTube and iPhone era, network reliability, data speed and battery power are increasing year by year. To provide a platform for high speed wireless connectivity and networking, a reliable high data rate is required. Thus, transmit diversity requires a plurality of antennas at the transmitter.

Accordingly, a search for a method for processing signals received from a plurality of transmitters and a plurality of antennas is required.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to group a plurality of symbols included in received signals received from a plurality of transmitters, and group the received signals into PIC ( The present invention provides a receiver for group decoding and a decoding method applied thereto.

According to an embodiment of the present invention, a receiver for receiving signals from a plurality of transmitters includes: a grouping unit for grouping a plurality of symbols included in the received signals received from the plurality of transmitters ; And a decoding unit to decode the grouped received signals by PIC group decoding.

In addition, the grouping unit may group eight symbols by two for the received signals, and group the total into four blocks.

Further, an equivalent channel matrix G for eight channels receiving eight symbols from the plurality of transmitters is

Each column vector of the matrix G is as shown below.

The grouping unit may group the eight column vectors by two into four blocks.

In addition, the grouping unit may group the two orthogonal column vectors into groups of four blocks in total.

The grouping unit may select any one of the following four schemes by grouping two orthogonal column vectors.

Scheme 1:

Scheme 2:

Scheme 3:

Scheme 4:

In addition, the grouping unit may group two non-orthogonal column vectors into groups of four blocks in total.

Meanwhile, according to an embodiment of the present invention, a decoding method of a receiver for receiving signals from a plurality of transmitters includes: grouping a plurality of symbols included in received signals received from the plurality of transmitters; And decoding the grouped received signals by partial interface cancellation (PIC) group.

In addition, in the grouping step, eight symbols may be grouped by two for the received signals and grouped into a total of four blocks.

Further, an equivalent channel matrix G for eight channels receiving eight symbols from the plurality of transmitters is

Each column vector of the matrix G is as shown below.

The grouping step,

The eight column vectors may be grouped by two and grouped into a total of four blocks.

In addition, the grouping step may be grouped into a total of four blocks by grouping two orthogonal column vectors.

The grouping step may select any one of the following four schemes by grouping two orthogonal column vectors.

Scheme 1:

Scheme 2:

Scheme 3:

Scheme 4:

In addition, in the grouping step, two non-orthogonal column vectors may be grouped in groups of four blocks.

According to various embodiments of the present disclosure, a receiver for grouping a plurality of symbols included in received signals received from a plurality of transmitters and performing a partial interface cancellation (PIC) group decoding on the grouped received signals and applied thereto It is possible to provide a decoding method, thereby implementing a block-by-block transmission technique having a high code rate, low complexity, and a low transmission time.

1 is a diagram illustrating a configuration of a wireless communication system according to an embodiment of the present invention;
2 is a graph illustrating symbol error rate (SER) performance of eight antenna layer PIC group decoding schemes, according to an embodiment of the present invention;
3 is a graph comparing SER of ML, PIC, and ZF decoding according to an embodiment of the present invention.

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

I. Introduction

Diversity based on Space-Time Block Coding (STBC) can be widely applied to future wireless communication standards such as 3GPP LTE and WiMax. Such STBC can implement transmit diversity without channel information. Although STBC was originally designed for two transmit antennas and one receive antenna, STBC has been extended to a system for four transmit antennas. In addition, research is being continued to apply the STBC system in a multi-user environment. In a multiple-input-multiple-output (MIMO) system, multiple antennas are used to increase the diversity order. Orthogonal STBC (OSTBC) with symbol-wise decoding is an Alamouti code. However, OSTBC has a low symbol rate as the number of transmit antennas increases. Accordingly, in order to achieve a high data rate, a layered OSTBC (LOSTBC) is proposed that divides the transmit antennas into different groups and codes information symbols within each group with independent OSTBCs. In contrast to the high complexity of Maximum-Likelihood (ML) decoding, the Group interface suppression method is used to detect information symbols encoded with layered space-time coding. In order to be applied to the LSTBC, the differentiated group interface removal method extracts a symbol from one STBC block corresponding to one group, removes interference with another group, and then completes decoding by performing ML decoding. Similar interface cancellation, Partial Interface Cancellation (PIC) group decoding, is used in the design of full-diversity space-time coding with low decoding complexity.

Hereinafter, a receiver 200 that performs PIC group decoding having orthogonal and non-orthogonal grouping structures will be described with reference to FIG. 1. PIC is performed here using a ZF operator. In the Alamoti structure, PIC group decoding is implemented for an interleaved Quasi orthogonal STBC having four blocks of four layers. Through this, it is intended to implement a block-by-block transmission technique having a high code rate, low complexity and low transmission time.

II. System model

1 is a diagram illustrating a configuration of a wireless communication system according to an embodiment of the present invention. As shown in FIG. 1, a wireless communication system includes a plurality of transmitters 100 and one receiver 200. In addition, the receiver 200 simultaneously receives signals from the plurality of transmitters 100.

Specifically, as shown in FIG. 1, the present embodiment considers a wireless communication system of a multiple input multiple output (MIMO) model. Here, four transmitters 100 transmit data simultaneously to one receiver. One transmitter includes two antennas.

In addition, the receiver 200 has one antenna 210, and the channels of the transmitter 100 and the receiver 200 are flat fading channels. Here, consider Alamouti Space Time Block Coding (STBC), which constitutes a high order interleaved code.

The receiver 200 performs grouping and PIC decoding of signals using the following operation process.

Alamouti STBC is represented by the following matrix.

The Alamouti matrix of equation (1) is based on two transmit antennas. The four transmit antennas can be obtained as follows using coordinated interleaved criterion.

From here,

to be.

In the same way, it can be defined as follows.

From here,

Is an information symbol (

, i = 1,2,3, ... 8 and A is the signal constellation. Here, the information symbol is an interleaved orthogonal structure. Equations (2) and (3) are block-diagonal matrices. ABBA Space-Time Block Code (STBC) for complexed square matrix

Consider.

then,

The matrix can be expressed as:

Information symbol of four transmitters 100

Are each encoded in the following block units.

Using such a block, the matrix S of Equation (5) can be expressed as follows.

The received signal of the receiver 200 can be expressed as follows.

From here,

And

Is the received signal of 4 type slots,

Is the average Signal-to-Noise-Ration (SNR) at the receiver. Also,

It is assumed that the channel matrix is a complex Gaussian distribution with an average 0 variance of 1.

From here,

to be. And,

,

,

, And

ego,

Denotes a transpose operation.

Is an additive white gaussian noise of average 0, variance 1. The received signals of four timeslots are given as follows.

From Equation (9), the following can be obtained.

Similarly, the following equations can be obtained from equations (10), (11), and (12), respectively.

Then, the following matrix can be obtained from equations (7), (13), (14), (15), and (16).

The model of Equation (17) can be expressed as follows in an equivalent form.

From here,

Is the received signal vector,

Is,

Is the noise vector,

Is an equivalent channel matrix.

Also,

Each element is as follows.

The receiver 200 receives a signal through an equivalent channel represented by such an equivalent channel matrix. It can be seen that the column vectors of the equivalent channel matrix described above satisfy the following conditions.

Using this, the following equation can be derived.

A. PIC Group Decoding

PIC group decoding performed at the receiver 200 reduces the complexity of decoding. Hereinafter, a preliminary process of decoding a partial interference cancellation (PIC) group will be described. As a preliminary process of Partial Interference Cancellation (PIC) group decoding, the grouping unit 220 of the receiver 200 groups the channel symbols of the received signal. The process is as follows.

From the equivalent channel matrix of Equation (18), it is possible to express vectors of the following general forms.

Using this, equation (18) can be expressed as follows.

Can be expressed as follows.

Here, the column vectors in the equivalent channel matrix G include four groups C ₁ , C ₂ , C ₃ and C ₄ . The projection matrix for the related groups can be expressed as follows.

As such, the receiver 200 performs grouping of channel symbols before performing PIC decoding and has different performance according to the grouping method.

B. PIC Grouping Based on Orthogonal Column Vectors

The grouping unit 220 may apply a scheme for selecting column vectors that are orthogonal to each other based on the equivalent channel matrix of Equation (17). The four orthogonal grouping schemes are shown below.

Scheme 1:

Scheme 2:

Scheme 3:

Scheme 4:

Normalizing the signal power in Eq. (24) gives the following equation.

Therefore, the orthogonal projection matrix is obtained by combining Equations (25) and (26) as follows.

Similarly, the following equation can be obtained.

Because the column vectors are orthogonal to each other, in the grouping scheme C ₁ = {1,3}, C ₂ = {2,4}, C ₃ = {5,7}, C ₄ = {6,8}

.

Then, the decoder 230 may PIC decode the grouped signals to obtain a request value of the received signal. In detail, an optimal reception signal calculated through PIC decoding of the decoding unit 230 may be obtained as follows.

That is, it is as follows.

Similarly, the decoding 230 can obtain an estimated value against the received signal through PIC decoding on other symbols.

C. PIC Grouping Based on Non-Orthogonal Column Vectors

For non-orthogonal PIC grouping, select non-orthogonal column vectors. For example,

Choose a grouping scheme. Considering non-orthogonal groupings, the following equation can be obtained.

Therefore, after applying the PIC group decoding at the receiver, the power gain for 8 symbols is calculated as follows.

After PIC is applied, the two pairs of vectors in the equivalent channel matrix are still orthogonal.

Through this process, the receiver 200 groups the received signals and performs PIC decoding.

Hereinafter, the configuration of the receiver 200 shown in FIG. 1 will be described.

The antenna 210 receives a received signal through eight channels from the plurality of transmitters 100.

The grouping unit 220 groups the plurality of symbols included in the received signals received from the plurality of transmitters 100. In detail, the grouping unit 220 groups the eight symbols by two for the received signals and groups the received signals into four blocks.

Here, the equivalent channel matrix G for eight channels receiving eight symbols from a plurality of transmitters is

Each column vector of the matrix G is as shown below.

In addition, the grouping unit 220 groups eight column vectors by two to group four blocks in total.

At this time, the grouping unit 220 groups the column vectors orthogonal to each other by two to group four blocks in total.

The grouping unit 220 may select any one of the following four schemes by grouping two orthogonal column vectors.

Scheme 1:

Scheme 2:

Scheme 3:

Scheme 4:

On the other hand, the grouping unit 220 may group two non-orthogonal column vectors into groups of four blocks in total.

The decoding unit 230 calculates an estimated value of the received signal by decoding the grouped received signals by PIC (Partial Interface Cancellation) group decoding.

Through this process, the receiver 100 can group the signals received from the plurality of transmitters 100 to PIC decode.

In the following description, a decoding method of the receiver 200 that receives signals from the plurality of transmitters 100 of FIG. 1 will be described.

First, the receiver 100 receives a reception signal through eight channels from a plurality of transmitters 100.

In addition, the receiver 200 groups a plurality of symbols included in the received signals received from the plurality of transmitters. In detail, the receiver 200 groups eight symbols by two for the received signals and groups the received signals into four blocks.

Here, the equivalent channel matrix G for eight channels receiving eight symbols from a plurality of transmitters is

And each column vector of the matrix G is as described above.

In addition, the receiver 200 groups eight column vectors by two to group four blocks in total.

At this time, the receiver 200 groups the column vectors orthogonal to each other by two to group four blocks in total. The receiver 200 may select any one of the following four schemes by grouping two orthogonal column vectors.

On the other hand, the receiver 200 may group two non-orthogonal column vectors into groups of four blocks in total.

Thereafter, the receiver 200 decodes the grouped received signals by partial interface cancellation (PIC) group to calculate an estimated value of the received signal.

Through this process, the receiver 100 can group the signals received from the plurality of transmitters 100 to PIC decode.

IV. Simulation analysis

Hereinafter, a simulation result for confirming the performance of PIC group decoding having an orthogonal grouping scheme and a non-orthogonal grouping scheme of the receiver 200 according to the present embodiment will be described. 2 is a graph illustrating symbol error rate (SER) performance of eight antenna layer PIC group decoding schemes according to an embodiment of the present invention.

Here, it can be seen that the receiver 200 according to the present embodiment shows a better SER. According to the communication system according to the present embodiment, the transmission time can be reduced. The channel model will have quasi-static Rayleigh fading. QAM modulation was applied in the simulation. As shown in FIG. 2, it can be seen that the SER performance varies according to the grouping scheme. The SER performance of orthogonal grouping is better than that of non-orthogonal scheme. 3 is a graph comparing SER of ML, PIC, and ZF decoding according to an embodiment of the present invention.

V. Conclusion

Up to now, the receiver 200 according to the present embodiment has applied PIC group decoding after detection of the quasi orthogonal STBC (QOSTBC) stratified in the signals received from the four transmitters 100. According to the present embodiment, the QOSTBC scheme of the receiver 200 achieves full diversity when PIC decoding is applied. In addition, applying the Alamouti structure, it is possible to apply PIC group decoding in four layers of interleaved QOSTBC divided into four blocks. Through this, it is possible to build a block-by-block transmission technique having a high code rate, low complexity and low transmission time.

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, but, on the contrary, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention.

100: a plurality of transmitters 200: receivers
210: antenna 220: grouping part
230: decoding unit

Claims (12)

In a receiver for receiving signals from a plurality of transmitters,
A grouping unit for grouping a plurality of symbols included in the received signals received from the plurality of transmitters; And
And a decoder configured to decode the grouped received signals by PIC group decoding.
The grouping unit,
For the received signals, eight symbols are grouped by two and grouped into a total of four blocks.
The equivalent channel matrix G for eight channels receiving eight symbols from the plurality of transmitters is

Each column vector of the matrix G is as shown below.

The grouping unit,
And grouping the eight column vectors by two into four blocks, and grouping the eight column vectors into four blocks by grouping two non-orthogonal column vectors into two groups.
delete delete The method of claim 1,
The grouping unit,
And grouping the column vectors orthogonal to each other into groups of four blocks in total.
5. The method of claim 4,
The grouping unit,
And selecting one of the following four schemes by grouping two orthogonal column vectors.
Scheme 1:

Scheme 2:

Scheme 3:

Scheme 4:

delete In the decoding method of a receiver for receiving signals from a plurality of transmitters,
Grouping a plurality of symbols included in the received signals received from the plurality of transmitters; And
And performing a partial interface cancellation (PIC) group decoding on the grouped received signals.
The grouping step,
For the received signals, eight symbols are grouped by two and grouped into a total of four blocks.
The equivalent channel matrix G for eight channels receiving eight symbols from the plurality of transmitters is

Each column vector of the matrix G is as shown below.

The grouping step,
And grouping the eight column vectors by two into four blocks, but grouping the two non-orthogonal column vectors by two into four blocks.
delete delete The method of claim 7, wherein
The grouping step,
And grouping the column vectors orthogonal to each other into groups of four blocks in total.
The method of claim 10,
The grouping step,
A decoding method comprising selecting one of the following four schemes by grouping two orthogonal column vectors.
Scheme 1:

Scheme 2:

Scheme 3:

Scheme 4:

delete

Images