KR101730238B1 - Method and apparatus for transmitting bitstream in a multiple input multiple output system - Google Patents

Abstract

The present invention discloses a bit stream transmission apparatus and method in a multi-antenna system. In a multi-antenna system according to the present invention, a bit stream transmission apparatus includes a coding and modulation unit for coding and modulating each of a plurality of packets obtained by packetizing the bit stream into a plurality of packets; And a second space-time coding method and a third space-time coding method, wherein each of the plurality of packets modulated by the coding and modulation section is combined with at least two coding methods among a first space-time coding method, a second space- A space-time coding unit for performing optimal space-time coding on packets; And a transmitter for transmitting the plurality of space-time coded packets.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an apparatus and a method for transmitting a bit stream in a multi-

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmission method using a multiple-input multiple-output (MIMO) channel, and more particularly, to a method and apparatus for transmitting a bitstream using a space- Technology.

 The demand for communication services such as generalization of communication services, appearance of various multimedia services and emergence of high quality services is rapidly increasing. Various wireless communication technologies are being investigated in various fields to satisfy this demand.

The next generation wireless communication system should be able to transmit high-quality, high-capacity multimedia data at high speed by using limited frequency resources. To enable this in a bandwidth-limited radio channel, it is necessary to overcome inter-symbol interference and frequency selective fading occurring during high-speed transmission while maximizing spectral efficiency. In addition, multiple input multiple output (MIMO) technology using multiple antennas is employed in various communication systems to maximize spectral efficiency.

The MIMO scheme can be used for two purposes. First, it can be used for the purpose of increasing the diversity gain to reduce the performance degradation due to the channel fading environment. Second, it can be used to increase the data rate in the same frequency band. In addition, in recent years, rapid packet processing has been required in a multi-antenna system in accordance with the trend of bandwidth expansion for high-speed communication.

Therefore, in order to process high-speed data, it is necessary to select an optimal coding method in coding data, and in particular, an optimal coding method is required in connection with various space-time coding methods.

An object of the present invention is to provide an apparatus and method for transmitting a bitstream in a multi-antenna system in which a bitstream can be transmitted by determining an optimal space-time coding scheme for transmitting data through a MIMO channel.

According to an aspect of the present invention, there is provided a bitstream transmission apparatus in a multi-antenna system, comprising: a coding and modulating unit for coding and modulating a plurality of packets each packetized into a plurality of packets; And a second space-time coding method and a third space-time coding method, wherein each of the plurality of packets modulated by the coding and modulation section is combined with at least two coding methods among a first space-time coding method, a second space- A space-time coding unit for performing optimal space-time coding on packets; And a transmitter for transmitting the plurality of space-time coded packets.

According to another aspect of the present invention, there is provided a method of transmitting a bitstream in a multi-antenna system, comprising the steps of: coding and modulating each of a plurality of packets obtained by packetizing the bitstream into a plurality of packets; Simulating each of the plurality of coded and modulated packets by combining at least two space-time coding schemes among a first space-time coding scheme, a second space-time coding scheme, and a third space-time coding scheme; Performing optimal space-time coding on the plurality of packets according to a simulation result of space time coding; And transmitting the plurality of space-time coded packets.

According to the present invention, an optimal space-time coding scheme can be selected through a minimum space-time coding simulation in the transmission of a bitstream, thereby enabling a bitstream to be transmitted at a high speed.

1 is a block diagram illustrating one embodiment of a station performing methods in accordance with the present invention.
2 is a reference diagram illustrating a narrowband MIMO system including multiple transmit and receive antennas.
3 is a graph showing the outage probability of two space-time codes at the same spectral efficiency.
4 is a graph showing DMT characteristics of D-BLAST, V-BLAST and OSTBC.
5 is a block diagram of an embodiment of a bitstream transmission apparatus in a multi-antenna system according to the present invention.
6 is a graph showing the outage probability of D-BLAST and OSTBC.
7 is a graph showing the outage probability of D-BLAST and V-BLAST.
8 is a graph showing an example of the outage probability of D-BLAST, V-BLAST, and OSTBC.
FIG. 9 is a graph illustrating another example of the outage probability of D-BLAST, V-BLAST, and OSTBC.
10 is a graph illustrating an example of PSNR performance.
11 is a graph of another example showing PSNR performance.
12 is a graph illustrating another example of the outage probability of D-BLAST, V-BLAST, and OSTBC.
13 is a graph illustrating another example of the outage probability of D-BLAST, V-BLAST, and OSTBC.
14 is a graph of another example showing PSNR performance.
15 is a graph of another example showing PSNR performance.
16 is a flowchart illustrating a method of transmitting a bitstream in a multi-antenna system according to an embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the relevant art and are to be interpreted in an ideal or overly formal sense unless explicitly defined in the present application Do not.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the present invention, the same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

Throughout the specification, the network can be, for example, a wireless Internet such as WiFi (wireless fidelity), a wireless broadband internet (WiBro) or a portable internet such as world interoperability for microwave access (WiMax) A 3G mobile communication network such as Wideband Code Division Multiple Access (WCDMA) or CDMA2000, a high speed downlink packet access (HSDPA), or a high speed uplink packet access (HSUPA) A 3.5G mobile communication network, a 4G mobile communication network such as an LTE (Long Term Evolution) network or an LTE-Advanced network, and a 5G mobile communication network.

Throughout the specification, a terminal is referred to as a mobile station, a mobile terminal, a subscriber station, a portable subscriber station, a user equipment, an access terminal, And may include all or some of the functions of a terminal, a mobile station, a mobile terminal, a subscriber station, a mobile subscriber station, a user equipment, an access terminal, and the like.

Here, a desktop computer, a laptop computer, a tablet PC, a wireless phone, a mobile phone, a smart phone, a smart watch, smart watch, smart glass, e-book reader, portable multimedia player (PMP), portable game machine, navigation device, digital camera, digital multimedia broadcasting (DMB) A digital audio recorder, a digital audio player, a digital picture recorder, a digital picture player, a digital video recorder, a digital video player ) Can be used.

Throughout the specification, a base station is referred to as an access point, a radio access station, a node B, an evolved node B, a base transceiver station, an MMR mobile multihop relay) -BS, and may include all or some of the functions of a base station, an access point, a radio access station, a Node B, an eNodeB, a base transceiver station, and a MMR-BS.

1 is a block diagram illustrating one embodiment of a station performing methods in accordance with the present invention.

Referring to FIG. 1, a station 100 may include at least one processor 110, a memory 120, and a network interface device 130 for communicating with a network. In addition, the station 100 may further include an input interface device 140, an output interface device 150, a storage device 160, and the like. Each component included in the station 100 may be connected by a bus 170 and communicate with each other.

The processor 110 may execute a program command stored in the memory 120 and / or the storage device 160. The processor 110 may refer to a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which the methods of the present invention are performed. The memory 120 and the storage device 160 may be composed of a volatile storage medium and / or a non-volatile storage medium. For example, memory 120 may be comprised of read only memory (ROM) and / or random access memory (RAM).

Hereinafter, related arts for explaining a bit stream transmission apparatus and method in a multi-antenna system according to the present invention will be described.

1. Cross-point analysis of outage probability for DMT (diversity multiplexing tradeoff) function

2 is a reference diagram illustrating a narrowband MIMO system including multiple transmit and receive antennas. Referring to FIG. 1, a narrowband MIMO system is presented that includes a transmit antenna N _t and a receive antenna N _r over a frequency flat fading channel.

size

Space-time code

Is transmitted over the transmit antenna N _t during the symbol duration T. [ The baseband equivalent model of the MIMO system in the k-th symbol duration (k = 1, 2, ..., T) is given by:

Here, S _k denotes an N _t × 1 transmission signal vector, y _k denotes an N _r × 1 reception signal vector, n _k denotes an N _r × 1 noise vector at the output of the matched filter, H is N _r x N _t channel metrics.

Next, an outage probability expression of the space-time code for a given distributed-linear DMT function can be derived.

Where r and d represent the multiplexing and diversity gain.

Quot; means spectral efficiency, and "

Means the probability of outliers.

Equation (2) can be expressed by the following equation (4) by L'Hopital's theorem.

Equation (4) can be expressed as Equation (5).

Integrating both sides of Equation (5) is expressed by Equation (6).

Here, c _r means a temporary real number.

Can be expressed by the following Equation (7).

In a similar way, from the theorem of L'Hopital, Equation 3 can be expressed as Equation 8:

And

Can be expressed by the following equation (10).

Here, let us consider a space-time code given by the DMT characteristic function as shown in the following equation (11).

here,

Represents an outage probability for a space-time code having a DMT characteristic function of Equation (11). From Equation (10) and Equation (11)

If

Can be expressed by the following equation (12).

Equation (7) can be expressed by the following Equation (13).

Herein, the inequality is

And

. Equation (13) is substituted into Equation (12)

If so,

Can be expressed by the following equation (14).

here,

Is derived as follows: < RTI ID = 0.0 >

(13), < RTI ID = 0.0 >

=

. Therefore, the inequality of the equation (13) and the inequality of the equation (11)

(14)

Range can be obtained.

The spectral efficiency, < RTI ID = 0.0 >

Is assumed to be unchanged. That is, regardless of the SNR

Is fixed. The reason for this will be described later. Therefore, future spectral efficiency,

Lt; / RTI > Hereinafter, a crossover point of outage probabilit curves will be described for a given piecewise-linear DMT function of space-time codes.

A. If there is a crossover point in the DMT function

First, a case where an intersection exists in the DMT characteristic function will be described.

Let us consider two space-time codes with linear DMT characteristics as shown in Equation (15).

Here, it is defined as follows.

That is, for two DMT functions

There is a crossover in the range.

And

The DMT function

And

And outage probabilities of the space-time codes given to each of them. From Equation 14,

, The following expression (19) can be obtained.

At this time,

to be.

From equation (19), at a given spectral efficiency R, the SNR

, And

And

Are identical. Also,

About,

Is expressed by the following equation (20).

Hereinafter, within the range of SNR in Equation 19

Will exist. And

, To be precise,

.

i) From equations (17) and (18)

, Or equivalently,

. Also,

Can be expressed as

Ii)

And

(17) and (18)

And

Respectively. From this and the inequality of Equation 13, the following Equation 21 can be obtained.

Furthermore,

And

Lt; RTI ID = 0.0 >

Quot;

, It is a strictly increasing function in R. In other words, as the spectral efficiency increases, the crossover point of the outage probability curve increases monotonically in the SNR.

Given by equation (20)

Is substituted into the equation (19), the corresponding outage probability,

Is given by the following equation (22).

In R

Is a strictly decreasing function:

And

≪ RTI ID = 0.0 >

Can be expressed as Assumption (15)

And < RTI ID = 0.0 >

From this,

. therefore,

Can be obtained. From this,

And

ego,

. Also,

The following equation (23) is obtained.

And

(22) and (23) for R <

Is an absolute decreasing function. That is, as the spectral efficiency increases, the crossover point in the outage probability decreases monotonically.

Further, equations (19) and

The following equation (24) is obtained.

And

Spectral efficiency < RTI ID = 0.0 >

Quot; indicates a crossover point when used,

And

Spectral efficiency < RTI ID = 0.0 >

Is the crossover point in the case where the above is adopted.

Quot;

And

Is a strictly decreasing and increasing function at R, respectively, and the following equation 25 can be obtained.

Based on equations (24) and (25), the outage probabilities of the two space-time codes for the same given spectral efficiency are qualitatively shown in FIG. Target outage probability,

The

Though smaller,

. By the way, referring to FIG. 3, spectral efficiency,

Given by equation (15)

Time-space code with DMT of

Of the time-space code with DMT of. However, spectral efficiency,

The latter is more preferable than the former. It should be noted that the analysis so far

And

Is effective.

B. If the DMT function matches the minimum Multiplexing Gain

Next, the DMT function

(Multiplexing Gain) in the range of < / RTI > Let us consider two space-time codes having linear DMT characteristics given by the following equations (26) to (28) and (15).

Below,

And

.

I)

, From this assumption and from Equation 27 and Equation 28,

And

. From this,

Result that does not match

. ≪ / RTI >

Ii) Next, it is assumed that u ₁ = u ₂ . Then, from equations (27) and (28), v ₁ = v ₂ and v ₁ < v ₂ are derived, which is a contradiction.

Iii) Finally, it is assumed that u ₁ > u ₂ . Then, according to equations (27) and (15)

, V ₁ > v ₂ is derived.

v ₁ > v ₂ , and from equation (27)

. Therefore,

Is in the range of the SNR given by Equation (19) in the same way as the following Equation (29).

Furthermore, from u ₁ > u ₂ and v ₁ > v ₂ ,

Quot;

If it is a range, it is an absolute increasing function in R. From u ₁ > u ₂ and v ₁ > v ₂ , equation

. In Equation 15, And u ₂ > 0

Can be obtained. therefore,

Can be obtained. From u ₂ > 0 and u ₁ > u ₂ ,

Lt; / RTI > Further, from v ₁ &gt; v ₂ , the following equation (30) is shown.

From equations (22) and (30), for k _d > 0 and k _r > 0,

Is a strictly decreasing function. That is, as the spectral efficiency increases, the crossover point in the outage probability decreases simply.

Further, from the equation (19) and v ₁ > v ₂ , the following equation (31) is expressed.

From Equation (31), any spectral efficiency R and target outage probability

, The maximum SNR

Except where otherwise provided,

Space-time code with a DMT given by

It is preferable to the space time code having the DMT given by Note that this differs from the result shown in equation (25). However, as shown in Equations (29) and (30), the crossover point

And

(32) &lt; / RTI &gt;

C. If the DMT function matches only in the maximum multiplexing gain

here,

, The DMT function is matched only at the maximum multiplexing gain. In the following equations (33) to (35), two space time codes having a linear DMT characteristic given by equation (15) are assumed.

By the method of the following equation (36), the following equation

Is within the range of the SNR given by Equation (19).

Further, the following equation 37 is shown.

That is, with the exception of the minimum SNR,

About,

The space-time code with the DMT given by

Is preferable to the space time code having the DMT given by &lt; RTI ID = 0.0 &gt;

D. For any DMT function for any Multiplexing Gain

If the DMT function has a full range

We will consider other cases throughout. Consider two time-space codes having linear DMT characteristics given by the following equations (38) to (40) and (15).

For all u _i and v _i (i = 1, 2) that satisfy equations 38 through 40,

,

And

to be. For each of the above sets,

Lt; / RTI &gt; does not lie within the range of the SNR given by equation (19).

I)

: &Lt; RTI ID = 0.0 &gt;

And from Equation 39,

, ie,

to be.

Ii)

: From equation (19)

And

This same

Is not present.

Iii)

: &Lt; RTI ID = 0.0 &gt;

And from equation (40)

, ie,

to be.

Next, the following equation 41 is shown for each of the sets.

I)

From equation (19)

in

Is an absolute decreasing function. already

Lt; RTI ID = 0.0 &gt; (41) &lt; / RTI &gt;

Ii)

: From Equation (19) and Equation (13), from Equation (41), Equation (41) holds.

Iii)

From equation (19)

in,

Is an absolute increasing function.

, Equation (41) is valid.

From equation (41), it can be seen that any R and

About,

The space-time code with the DMT given by

It is preferable to the space-time code having the DMT given by Eq.

E. If the DMT functions match

Finally,

Consider a case where the DMT functions match over the entire range. We consider two space-time codes with linear DMT characteristics given by: &lt; EMI ID = 15.0 &gt;

From the equations (19) and (42), the following equation (43) is established.

That is, both space-time codes are both equally preferable.

2. Cross-point analysis of outage probability curves for D-BLAST, V-BLAST and OSTBC

We will analyze the behavior of the crossover point of the outage probability curves for a particular space-time code. For example, three space-time codes corresponding to two-layer D-BLAST with a group zero-forcing receiver, V-BLAST with an MMSE receiver, and OSTBC with an decorrelator .

Group decoding is a recent decoding scheme. By dividing all the symbols into multiple groups, the group zero-forcing decoding is performed in two stages, the interference from all other groups disappears and the coding of the symbols in the current group is maximized It is expected. D-BLAST, V-BLAST, and OSTBC are considered together with the specific receiver.

each

,

And

The DMT characteristics of D-BLAST, V-BLAST, and OSTBC, denoted by Equation 44, 45 and 46,

For example, the DMT characteristic for a 3x3 MIMO system is shown in FIG. 4 is a graph showing DMT characteristics of D-BLAST, V-BLAST and OSTBC. To compare the space-time codes,

.

A. Two-layer D-BLAST with a Group Zero-Forcing Receiver and V-BLAST with MMSE receiver

First, D-BLAST and V-BLAST are analyzed. The range of multiple gains given by equations (44) and (45) is such that the DMT function of both D-BLAST and V-BLAST is linear over the whole

,

,

And

. For each range, analyze the intersection of the out- put probability curves of D-BLAST and V-BLAST.

I)

: For this range, the result according to equation (41)

(I.e., D-BLAST is preferable to V-BLAST).

Ii)

: For this case, the results according to equations (24) and

(I. E., The intersection in the outlier probability curve,

And

Lt; / RTI &gt;

V-BLAST is preferable to D-BLAST. In other cases, D-BLAST is preferred; As the spectral efficiency increases,

And

Exhibit monotonic behavior.

Iii)

: In this case, the result according to equation (37)

(I. E., &Lt; / RTI &gt;

V-BLAST is preferred to D-BLAST, except when the &lt; / RTI &gt;

Iv)

: For this range, the result according to equation (43)

(I.e., both D-BLAST and V-BLAST are preferred).

And

Represent the outage probabilities of D-BLAST and V-BLAST. The results of i), ii), iii), and iv) are summarized as in the following equation (47).

here,

The

Lt; / RTI &gt; And a monotonic behavior as shown by equation (25).

Target outage probability,

The

Smaller than

. Then, from equations (47) and (48), the spectral efficiency

D-BLAST is preferable to V-BLAST. But,

V-BLAST is preferable.

B. Two-Layer D-BLAST with Group Zero-Forcing Receiver and OSTBC with Decorrelator Next, D-BLAST and OSBTC are analyzed. For DMT functions of both D-BLAST and OSTBC to be linear in each range, the range of multiple gains given by equations 44 and 46 is

,

,

, And

. first,

Is considered.

Case 1:

I)

: For this range, the results according to equations (24) and

(I. E., The intersection in the outlier probability curve,

And

Lt; / RTI &gt;

D-BLAST is preferable to OSTBC. In other cases, OSTBC is preferred. As the spectral efficiency increases,

And

Shows a forging movement.

Ii)

: The result according to equation (41)

(I.e., D-BLAST is preferred over OSTBC).

Iii)

: The result according to equation (37)

(Ie, D-BLAST maintains the range

&Lt; / RTI &gt; is preferred over OSTBC).

Iv)

: The result according to equation (43)

(I.e., both D-BLAST and OSTBC are preferred).

Represents the outage probability of the OSTBC. The results of i), ii), iii), and iv) are summarized as follows.

here,

Within the range of

Lt; / RTI &gt; And this represents the monotonic motion given by equation (25).

Case 2:

I)

: The result according to equation (37)

(Ie, OSTBC maintains a range of

Is preferable to D-BLAST).

Ii)

: The results according to equations (31) and (32)

(Ie, D-BLAST will maintain a range of

&Lt; / RTI &gt; is preferred over OSTBC;

, As the spectral efficiency increases, the crossing point

And

Shows a forging movement).

Iii)

: The same result as Case 1.

Iv)

: The same result as Case 1.

The results of i), ii), iii), and iv) may be summarized as in Equation 49; However, the crossover point is exactly

to be; This also represents the monotonic behavior given by equation (32), as shown in equation (50).

Case 3:

I)

: For this range, the result according to equation (41)

(Ie, OSTBC is preferable to D-BLAST).

Ii)

: The results according to equations (24) and (25)

(I.e., a crossover point within the outage probability curves)

And

Lt; / RTI &gt; D-BLAST

, And in other cases, OSTBC is preferred; As the spectral efficiency increases, the crossover point increases,

And

Shows a forging motion.

Iii)

: The result is the same as Case 1.

Iv)

: The result is the same as Case 1.

The results of i), ii), iii), and iv) may be summarized as in equation 49; But,

The

Lt; / RTI &gt;; This also shows the monotonic motion given by Eq. (25), as shown in equation (50).

Target outage probability,

silver

Though small

. And, for Cases 1, 2 and 3, in Equations 49 to 50, the spectral efficiency,

OSTBC is preferable to D-BLAST. But,

D-BLAST is preferable (see Fig. 3).

C. V-BLAST with MMSE receiver and OSTBC with decorrelator

In a similar manner, V-BLAST and OSTBC can be expressed as: &lt; EMI ID = 51.0 &gt;

here,

The

&Lt; / RTI &gt; And this represents a monotonic motion as given by equation (25): &lt; RTI ID = 0.0 &gt;

Outage probability,

this

Smaller,

. Then, from equations (51) and (52), the spectral efficiency,

OSTBC is preferable to V-BLAST. But,

V-BLAST is preferable. Note that the results are consistent with the analytical results for V-BLAST and OSTBC with zero-forcing receiver. Since the DMT function of the MMSE Re-Server and the zero-forcing receiver for V-BLAST are exactly the same, the results do not miss our expectation.

3. Optimal space-time coding of progressive bitstream

For a progressive source, in terms of a target error rate and a transmission data rate.

Progressive encoders generate encoded data with progressive differences in importance in the bitstream.

5 is a block diagram of an embodiment of a bitstream transmission apparatus in a multi-antenna system according to the present invention. Referring to FIG. 5, it is assumed that a bitstream from a progressive source encoder is converted into a sequence of a plurality of packets N _P. In order to achieve optimal performance as measured by the expected distortion of the source, each of the plurality of packets may be encoded with different time-space codes as well as different transmission data rates. In progressive transmission, since the importance decreases gradually, the error rate of a packet ahead of a later packet needs to be smaller or equal. Therefore, at the same transmission power, the preceding packet requires a transmission data rate equal to or smaller than the latter packet.

N _R is defined as the number of candidate transmission data rates adopted in the system. As N _P increases, the number of possible tasks of the Nr data rate for the N _P packet increases exponentially. Moreover, in a MIMO system, the task of data rate for N _P packets as well as space-time codes can be more complex (e.g., D-BLAST, V-BLAST or OSTBC) if each packet can be encoded with different time- Resulting in optimization problems. Each source, such as an image, has inherent bit-distortion characteristics from which the performance of the expected distortion is measured. Thus, for example, when a continuous image is transmitted, the optimization must be performed in a real-time manner and consideration must be given to which particular image (i.e., bit-distortion characteristic) is transmitted in the slot of the current time. To address this problem, there has been research into the optimization problem of the data rate for a sequence of progressive packets for the SISO system.

For a progressive source, the error rate of the preceding packet must be less than or equal to the error rate of the late packet. The preceding packet needs to be smaller than or equal to the transmission data rate of the late packet.

First, focus on D-BLAST and V-BLAST. D-BLAST or V-BLAST may be adopted for each progressive packet. In the sequence of N _P packets, the kth packet should be encoded by V-BLAST rather than D-BLAST. This analysis then requires that the k + 1th, k + 2th ... N _P th packet also be encoded as V-BLAST rather than D-BLAST. That is, V-BLAST is preferred for packets with a data rate of Rf (ie, spectral efficiency), and if the target error rate of the latter packet is greater than or equal to the target error rate of the electronic packet, Rg > Rf) must also be encoded in V-BLAST (see FIG. 3). That is, in the sequence of Np progressive packets, consecutive packets of the last i should be encoded in V-BLAST and the rest N _P -i packets in D-BLAST (

).

Next, it is assumed that D-BLAST or OSTBC can be adopted for each packet, and the kth packet is encoded to OSTBC. Then, the 1st, 2nd ...., k-1th packets should also be encoded in OSTBC. If OSTBC is desired for a packet with a rate of Rg, then the conclusion is drawn that if the latter target error rate is less than or equal to the former target error rate, then the packet with a rate of Rf (< Rg) can do. Therefore, even if the remaining Np-i packets are encoded in D-BLAST, the successive packets of the first i should be encoded in OSTBC (

).

From the above conclusion, the optimization strategy for D-BLAST, V-BLAST and OSTBC can be derived as follows. It is assumed that the system can employ D-BLAST, V-BLAST or OSTBC for each progressive packet. The consecutive packets of the initial i must be encoded with OSTBC, the contiguous packets of the last j must be encoded with V_BLAST, and the remaining Np-ij packets must be encoded with D-BLAST (

). The optimization technique is based on the characteristics of the progressive source in relation to the irregular target error rate and spectral efficiency in the bitstream.

In conclusion, the number of possible tasks of the three space-time codes for the Np packet is

in

. The computational complexity of optimization techniques can be exponentially simple.

Hereinafter, an apparatus and method for transmitting a bitstream in a multi-antenna system according to an embodiment of the present invention will be described in detail.

FIG. 5 is a block diagram of an embodiment of a bitstream transmission apparatus in a multi-antenna system according to the present invention, which includes a coding and modulation unit 200, a space-time coding unit 210, and a transmission unit 220.

A progressive source bitstream is packetized into a plurality of packets. An embedded bitstream may be input and packed into a plurality of packets.

The coding and modulation unit 200 codes and modulates each of a plurality of packets obtained by packetizing the bit stream into a plurality of packets, and delivers the coded and modulated packets to the space time coding unit 210. For example, the coding and modulation unit 200 codes and modulates the input N packets based on the respective transmission data rates. N packets arranged on a predetermined basis are described as a first packet (first packet), a second packet (second packet), ..., and an Nth packet (Npacket). And the first packet (1st packet), the second packet (2nd packet), ..., the transmitted data rate (Transmission data rate) corresponding to the N-th packet (Npacket) R1, R2, ... , R N-1, R _N ).

The coding and modulation unit 200 codes and modulates the packets arranged according to importance. In the case where the arranged packets are arranged in descending order of importance from the order of importance, coding and modulation can be performed based on a relatively low coding order or a transmission data rate in the case of relatively high priority packets And allows coding and modulation to be performed based on a relatively high coding order or a transmission data rate in the case of packets with relatively low importance. For example, the first packet (1st packet), the second packet (packet 2nd), ..., the transmitted data rate (Transmission data rate) corresponding to the N-th packet (Npacket) has R1, R2, ..., R _{N -1} and R _N and the importance decreases from the first packet to the N-th packet (Npacket), the coding and modulation unit 200 generates a first packet having a relatively high priority, The second packet or the like may be coded and modulated on the basis of a relatively low coding order or a transmission data rate and the N-1th packet (N packet) or So that coding and modulation can be performed based on a relatively high coding order or a transmission data rate in the case of the Nth packets.

The space-time coding unit 210 converts each of a plurality of packets, which are coded and modulated by the coding and modulation unit 200, into at least two coding schemes among a first space-time coding scheme, a second space-time coding scheme and a third space- And performs optimal space time coding on the plurality of packets according to the combined simulation result.

The space-time coding unit 210 combines at least two coding schemes among the first space-time coding scheme, the second space-time coding scheme, and the third space-time coding scheme to simulate space-time coding. Here, the first space-time coding scheme corresponds to an OSTBC (Orthogonal Space Time Block Codes) scheme, the second space-time coding scheme corresponds to a D-BLAST (Diagonal-Bell Laboratories Layered Space Time) scheme, Coding scheme may correspond to a V-BLAST (Vertical-Bell Laboratories Layered Space-Time) scheme.

 However, the first space-time coding scheme, the second space-time coding scheme, and the third space-time coding scheme are not limited to this, but may be applied to other schemes. Hereinafter, it is assumed that the first space-time coding scheme corresponds to the OSTBC scheme, the second space-time coding scheme corresponds to the D-BLAST scheme, and the third space-time coding scheme corresponds to the V-BLAST scheme.

When the plurality of packets are composed of first through N-th (where N is a positive integer greater than 1) packets, the space-time coding unit 210 sequentially arranges the first through the I- , I is a positive integer greater than 1 and less than N) time-space coding using the first space-time coding scheme, and for each of the sequentially arranged I + 1 to Nth packets, Time-space coding can be simulated using a space-time coding scheme. Also, when the plurality of packets are composed of first through N-th (where N is a positive integer greater than 1) packets, the space time coding unit 210 sequentially transmits the first through I (Where I is a positive integer greater than 1 and less than N) packets using the first space-time coding scheme, and sequentially arranges the I + 1 packets through K, (K + 1) th packet to the (N + 1) th packet arranged sequentially, using the second space-time coding scheme for packets having positive integers larger than I + 1 and smaller than N, You can also use a coding scheme to simulate space-time coding.

The space-time coding unit 210 sequentially transmits at least two coding schemes among the first space-time coding scheme, the second space-time coding scheme and the third space-time coding scheme sequentially from the order of high packet importance to the plurality of packets Can be combined to simulate space-time coding. At this time, the target outage probability for the packet after the adjacent two packets among the arranged packets is equal to or greater than the target outage probability for the preceding packet. This is because the less significant the packets behind the arranged packets are. That is, the space-time coding unit 210 can simulate space-time coding considering at least one of a target outage probability and a target bit error rate for a plurality of packets .

The space-time coding unit 210 performs a space-time coding based on the first space-time coding scheme, the second space-time coding scheme, and the third space-

(Where N is the number of packetized packets of the bit stream). The space time coding unit 210 does not simulate all the methods for space-time coding each packet by applying all the methods of the first space time coding method, the second space time coding method and the third space time coding method,

Simulate only for the number of branches. Since at least one of the first space time coding method, the second space time coding method and the third space time coding method is used in the method of space-time coding one packet, the number of all cases The

. However, the present invention does not simulate all cases,

Simulate only the branch method.

Referring to FIG. 2 described above, the outage probabilities of two space-time codes for the same spectral efficiency are qualitatively shown. Target outage probability,

The

Though smaller,

. Spectral efficiency,

Given by equation (15)

Time-space code with DMT of

Of the time-space code with DMT of. However, spectral efficiency,

The latter is more preferable than the former.

A space-time coding unit 210 for performing optimal space-time coding on a plurality of packets by combining at least two coding schemes among a first space-time coding scheme, a second space-time coding scheme, and a third space- Is as follows.

In comparison of a 2-layer D-BLAST with a Group Zero-Forcing Receiver and a V-BLAST with an MMSE receiver, the range of multiple gains given by Equations 44 and 45 is

,

,

And

.

I)

, The result according to the above-described equation (41)

D-BLAST is preferable to V-BLAST in that it maintains the range of &quot; V-BLAST &quot;. therefore,

The space-time coding unit 210 performs D-BLAST coding.

Ii)

, The results of the above-described expressions (24) and (25)

In the range of &lt; RTI ID = 0.0 &gt;

V-BLAST is preferable to D-BLAST. therefore,

, The space time coding unit 210

And performs D-BLAST coding in other cases.

Iii)

, The result according to the above-described expression (37)

In the range of &lt; RTI ID = 0.0 &gt;

V-BLAST is preferable to D-BLAST. therefore,

, The space time coding unit 210

V-BLAST coding is performed.

Iv)

, The result according to the above-mentioned equation (43)

, Both D-BLAST and V-BLAST are preferable. therefore, The space time coding unit 210 may selectively perform D-BLAST or V-BLAST coding.

Also, when comparing a two-layer D-BLAST with a group zero-forcing receiver and an OSTBC with a decorrelator, the range of multiple gains given by equations 44 and 46 is

,

,

, And

. first,

Is considered.

Case 1:

I)

, The results of the above-described expressions (24) and (25) In terms of maintaining the range of

D-BLAST is preferable to OSTBC. In other cases, OSTBC is preferred. therefore,

, The space time coding unit 210

D-BLAST coding is performed on the D-BLAST coding, and OSTBC coding is performed in other cases.

Ii)

, The result according to the above-described equation (41)

D-BLAST is preferable to OSTBC in that it maintains the range of &quot; D-BLAST &quot;. therefore,

The space-time coding unit 210 performs D-BLAST coding.

Iii)

, The result of Equation (37)

In keeping with the range, D-BLAST

Is preferable to OSTBC. therefore,

, The space time coding unit 210

D-BLAST coding is performed.

Iv)

, The result according to the above-mentioned equation (43)

D-BLAST and OSTBC are all preferable in terms of maintaining the phosphorus range. therefore,

The space time coding unit 210 may selectively perform D-BLAST or OSTBC coding.

Case 2:

I)

, The result according to the above-described expression (37)

OSTBC, in terms of maintaining a range of

Is preferable to D-BLAST. therefore,

, The space time coding unit 210

OSTBC coding is performed.

Ii)

, The results of the above-described expressions (31) and (32)

D-BLAST has the potential to

Is preferable to OSTBC. therefore,

, The space time coding unit 210

D-BLAST coding is performed.

Iii)

, Which is the same as Case 1.

Iv)

, Which is the same as Case 1.

Case 3:

I)

, The result according to the above-described equation (41)

OSTBC is preferable to D-BLAST in that it maintains the range. therefore,

The space time coding unit 210 performs OSTBC coding.

Ii)

, The results of the above-described expressions (24) and (25)

D-BLAST has the potential to

, And in other cases, OSTBC is preferable. therefore,

, The space time coding unit 210

D-BLAST coding is performed in a range of 0 to 5, and OSTBC coding is performed in other cases.

Iii)

, The result of Case 1 is the same.

Iv)

, The result of Case 1 is the same.

Target outage probability,

silver

Though small

. And, for Cases 1, 2 and 3, in Equations 49 to 50, the spectral efficiency,

OSTBC is preferable to D-BLAST. But,

, D-BLAST is preferable.

In addition, a comparison between the V-BLAST having the MMSE receiver and the OSTBC having the decorrelator can be expressed as Equation (51). here,

The

&Lt; / RTI &gt; And this shows forging motion as given by equation (25).

Outage probability,

this

Smaller,

. Then, from Equations 51 and 52 described above, the spectral efficiency,

OSTBC is preferable to V-BLAST. But,

V-BLAST is preferable. The results are consistent with the analytical results for V-BLAST and OSTBC with a zero-forcing receiver.

Space-time coding unit 210 performs time-space coding based on the OSTBC sequentially for each of the arranged packets when performing a simulation to obtain an optimal space-time coding method for each packet, and sequentially encodes the D-BLAST and V When performing space-time coding based on -BLAST, a method of performing space-time coding based on OSTBC again on a packet arranged after a time-space coded packet based on the initial D-BLAST or V-BLAST is not simulated.

Packets arranged after a time-space coded packet based on D-BLAST or V-BLAST for the first time among the arranged packets are better than space-time coding based on D-BLAST or V-BLAST than space-time coding with OSTBC. Also, when coding the first packet among the arranged packets into V-BLAST, only the last packet is coded based on V-BLAST.

That is, when space-time coding is performed based on any one of OSTBC, D-BLAST, or V-BLAST sequentially for a plurality of packets, when a specific packet is space-time coded on the basis of V-BLAST, The packets arranged after the coded packet are time-space coded based on V-BLAST.

Therefore, the space time coding unit 210 can apply the bit error rate (BER) instead of the outage probability or the target bit error rate instead of the target outage probability.

The transmitting unit 220 may transmit a signal based on a multiplexer. The transmitting unit 220 according to the embodiment of the present invention may include a plurality of antennas (not shown), and may transmit different signals for each antenna. In particular, the transmitting unit 220 transmits the plurality of time-space-coded packets to the receiving end.

 If the transmitter 220 transmits the space-time coded stream according to the OSTBC scheme, the receiver can receive the space-time coded stream through the decorrelator in accordance with the OSTBC scheme. In addition, when the transmitter 220 transmits the space-time coded BIS stream according to the D-BLAST scheme, the receiver receives the space-time coded BIS stream according to the D-BLAST scheme through a group zero forcing receiver . In addition, if the transmission unit 220 transmits the space-time coded BIS stream according to the V-BLAST scheme, the receiving unit transmits the space-time coded BIS stream according to the V-BLAST scheme to the group zero forcing receiver .

The above-described features of the present invention will be described with reference to the graphs.

First, the outage probability of D-BLAST, V-BLAST and OSTBC is numerically evaluated for various spectral efficiency and number of transmit and receive antennas. The results for the 2x3 and 2x4 MIMO systems are shown in Figures 6 and 7, respectively.

FIG. 6 is a graph showing the outage probability of D-BLAST and OSTBC, and FIG. 7 is a graph showing outage probability of D-BLAST and V-BLAST.

Here, the solid curve represents the exact outage probability, and the dash curve represents the outage probability about the high SNR, which is derived from equations (11), (14) and (44) to (46). is effective at an outage probability of about a high SNR for a range of k _d > 0 and k _r > 0.

6 and 7, the constant kd is matched in equation (14), and at low SNR,

. Here, the third quality follows the last line of equations (11), (14) and (44) to (46) (i.e., u = v = 0 is substituted into equation (14)). At low SNR, another constant kr is selected such that the SNR gap between the outlier probability about the high SNR and the correct outage probability is small.

Referring to FIG. 6 and FIG. 7, the accurate outlier probability can be calculated by the following equation [12, 20, 14, 15, and 22 for the OSTBC, D-BLAST, and V- (6) and (9). Note that in the above equation, for the calculation of the outage probability, the mutual information is normalized by the time duration of the space-time codeword (i.e., denoted by T in Equation 1). Figures 6 and 7 show that, with increasing spectral efficiency, the exact intersection point and the approximate intersection point behave in a manner predicted in the analysis given by equations (48) and (50).

8 is a graph showing an example of the outage probability of D-BLAST, V-BLAST, and OSTBC. In FIG. 8, the exact outage probabilities of D-BLAST, V-BLAST and OSTBC for a 2x2 MIMO system with some spectral efficiency are shown together. Focusing on the outage probability of 10 ^-3 , OSTBC is the best for 8 and 10 bits / s / Hz, while D-BLAST shows the best performance for 12 bits / s / Hz spectral efficiency. This preference is a function of the spectral efficiency as well as the target outage probability of the application. For example, if the target is 2 · 10 ^-1 , V-BLAST is best for 12 bits / s / Hz, whereas D-BLAST is best for 8 and 10 bits / s / Hz.

FIG. 9 is a graph illustrating another example of the outage probability of D-BLAST, V-BLAST, and OSTBC. Figure 9 shows the exact outage probability for a 4x4 MIMO system. As the spectral efficiency increases, it can be seen that the intersection acts according to the predictions of equations (48) and (50), similar to the 2x2 MIMO system. Compared to a 2 × 2 MIMO system, OSTBC performs better only at high SNRs. This is partially due to the fact that unlike the case of Nt = 2 where the Alamouti scheme achieves a multiplexing rate of 1, the multiplexing rate defined by the ratio of the number of symbols packed in the space-time codeword to the time duration of the space- multiplexing rate of Nt = 3 is only 3/4 for complex OSTBCs.

Hereinafter, the best space-time coding for the progressive transmission and the space-time coding of the lane are compared. Evaluate performance using a SPIHT (Equation 34) source coder for a 512 x 512 Lena image with a transmission rate of 8 bits per pixel (bpp) and 0.5 bpp. Optimal performance is measured by the expected distortion of the image.

The system accepts a compressed progressive bit stream and converts it into a sequence of N _P packets with error detection and error correction capability. At the receiver, if the received packet is correctly decoded, the next packet is predicted by the source decoder. Otherwise, decoding stops. And the source is rebuilt from the correctly decoded packet. Consider an image channel consisting of a sequence of N _P progressive packets with a slower fading channel that is almost equal to the constant channel coefficient.

Represents the probability of a decoding error of the i &lt; th &gt; packet (

). here

Is the instantaneous SNR per symbol for the i-th packet. Then, the probability that there is an error in the next packet but no decoding error occurs in the first n packets,

Is given by equation (53).

Is the probability of error occurrence in the first packet,

Is the probability that all N _P packets will be correctly coded. The first n packets (&lt; RTI ID = 0.0 &gt;

), The source distortion is

Can be expressed as

Represents the number of source bits in the ith packet,

Represents an operational distortion-rate function of the source. Then, the expected distortion of the source, E [D], is given by the following equation (54).

here,

Is given by equation (53), and for the i &lt; th &gt; packet,

The instantaneous SNR (

) &Lt; / RTI &gt; When n = 0,

to be. From Eqs. 53 and 53, E [D] can be written as

Is a symbol ( ) As well as the spectral efficiency and the average SNR per space-time code assigned to the i-th packet; Thus, E [D] is also a function of these parameters. D (0) SMS in Equation 55 indicates distortion for an event that an error exists in the first packet. For a still image, D (0) means reconstructing all the images in the average pixel A, so the image is useless. On the other hand, in the case of video, the decoder will repeat the previous frame for that frame. For low motion video, D (0) will not be large.

Ci represents the space-time code allocated to the i-th packet. An optimal set of space-time codes that minimizes the expected distortion for the range of SNRs using a weighted cost function such as Equation 56,

Can be found.

here,

Is a weighting function. For example,

About

Lt; / RTI &gt;

Is adopted, and if not

to be. In a broadcast or multicast system, the weighting function is defined as the SNR of multiple receivers &lt; RTI ID = 0.0 &gt;

Indicating that they are uniformly distributed in the range.

Equation (56)

A function of the space-time code, such that the total sum of the expected distortions of the receiver in the range is minimized,

Is adopted. Notice that the computational complexity associated with equation 56 increases exponentially with increasing N _P. Alternatively, a contiguous packet of the first i must be encoded by OSTBC, a contiguous packet of the last j must be encoded with V-BLAST, and the rest N _P -ij packets must be encoded with D-BLAST According to the code function,

Can be adopted (

).

To compare the quality of the images,

(dB) is used as the peak signal-to-noise ratio PSNR. PSNR performance can be evaluated as follows. First, the weight function given by Equation 56 and Equation 56 using the expected distortion, E [D], given by Equation 55,

. Next, the optimal code set obtained from equation (56)

, The range of SNR given by equation 56,

&Lt; / RTI &gt; As an example,

&Lt; / RTI &gt; is transmitted to a 2x2 MIMO system. 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 7.0, 8.0] (bits / sHz) when the i th component, Ri, is the spectral efficiency assigned to the ith packet So that the spectral efficiency is assigned. For this particular setup, the optimized set of space-time codes computed from equation 56 is C ₁ = OSTBC, C ₂ = C ₃ = ... = C ₉ = D-BLAST, and C ₁₀ = C ₁₁ = V-BLLAST. Figure 10 shows the worst case code set showing the best set of such space-time codes, the PSNR of the set of other interrupts, such as the 75th and 50th percentile set in the code set, and worst performance. Figure 10 also shows PSNR corresponding to the expected distortion averaged over a possible set of all space-time codes. From this example, the PSNR performance of the progressive source is seen to be sensitive to the manner in which the space-time code is assigned to the packet sequence, due in part to the unequal target error rate and the spectral efficiency of the bitstream.

Figure 10 also shows the PSNR performance when Equation 56 is calculated according to the constraints presented in Section IV. In this case, the number of possible sets of space-time codes is

to be. Note that the same optimization code set is obtained when Equation (56) is calculated, with or without the above constraints. That is, without any PSNR performance loss, the computational complexity of the optimization is lowered by the monotonic behavioral development of the intersection shown in FIG. Further, we can see that the PSNR performance corresponding to the expected distortion averaged over all possible code sets is better, which is, on average, a good strategy for space-time coding of progressive sources. The simulation parameters related to PSNR performance evaluation are summarized in Table 1.

Figure 11 shows the PSNR performance of the optimal space-time code set for 3x3 and 4x4 MIMO systems. Furthermore, this shows the performance of the optimization code set for events when only V-BLAST and OSTBC are adopted (i.e. excluded D-BLAST). For reference, FIG. 11 shows the performance when the outage probability is calculated from the mutual information of the MIMO channel. That is, for the i-th packet, the outage probability is obtained from the following equation (57).

here,

Is the spectral efficiency assigned to the packet. And

silver

&Lt; / RTI &gt; As shown in FIG. 11, the PSNR performance gap between the case where D-BLAST is included and the case where D-BLAST is included is significant. This suggests that when a progressive source is transmitted in a MIMO system, the performance of the PSNR may be improved if many space-time codes are considered for the packet sequence. This motivates the user to establish an optimization strategy for a variety of space-time codes, rather than staying in V-BLAST with a zero-forcing receiver and OSTBC that was considered in the prior art. Only three space-time coding, D-BLAST, V-BLAST and OSTBC, are considered. However, a receiver with a given DMT characteristic function and a progressive transmission employing various time-space codes can be optimized.

Hereinafter, i. Let us consider spatially correlated Rayleigh attenuation and Rician attenuation channels instead of MIMO Rayleigh attenuation channels. The multiplexing and DMT characteristics with the diversity gain at the high SNRs shown in equations (2) and (3) are not affected by spatial phase or line-of-sight (LOS) signal elements. In other words, the spatially correlated Rayleigh attenuation or Rician attenuation are the same for the i.i.d Raieigh attenuation. This is because, when the SNR converges to infinity, the number of channel eigenmodes determines the performance. That is, the relative intensity of the eigenmodes does not affect the high SNR behavior. The spatial correlation or LOS factor mainly affects the number of states of the channel matrix (ie, the ratio of the maximum single value to the minimum single value), and the effect of this transmission is not observed at high SNRs. From this, crossing analysis is valid for mutual Rayleigh attenuation or Rician attenuation channels at high SNR.

We numerically examine the characteristics of the intersection in the propagation channel. This propagation channel can be modeled as the following equation (58).

Where K> 0 is the Rician element. And

Represents the average channel matrix associated with the LOS signal element.

Of the Frobenius norm

Can be generalized as follows. And

Are known to the transmitter and receiver sides.

The

&Lt; / RTI &gt;

The

&Lt; / RTI &gt;

Represents the Hermitian square root of the matrix. And,

The

Represents the iid channel matrix.

And

Lt; RTI ID = 0.0 &gt; a &lt; / RTI &gt; here

Represents the (i, j) th element of the matrix,

And

Represents the transmit and receive spatial correlation coefficients between adjacent antennas, respectively. For example, for a 2x2 spatially correlated Rayleigh fading channel with various correlation coefficients, the exact outage probability is numerically evaluated.

The results in the case of FIG. 12 are shown in FIG. It can be seen that the intersection in the correlated Rayleigh attenuation channel behaves as in the iid Rayleigh attenuation channel. Next, an accurate outlier probability is evaluated for a 2 x 2 Rician attenuation channel. And the result for the Rician element corresponding to K = 2 is shown in FIG. Also, it can be seen that the intersection point behaves the same as in the iid Rayleigh attenuation channel.

Fig. 14

Value indicates a PSNR performance for a spatially correlated Rayleigh attenuation channel and a Rician attenuation channel with K = 2. Here, the other system parameters are the same as those for the iid Rayleigh attenuation channel. This result is shown in FIG. The following should be noted. For each propagation channel, an optimization set of the same space-time code can be obtained when equation (56) is computed depending on the presence or absence of constraints. Moreover, as with the results for iid Rayleigh attenuation, the PSNR performance corresponding to the expected distortion averaged over all possible sets of space-time codes is improved.

In FIG. 15, performance is checked for a 512 × 512 Pepper of 8 bpp and another image representing a 256 × 256 size photographer. Each of the images has a rate of 0.5 bpp in the Rayleigh attenuation channel.

In a hierarchical image, the base layer is more important than the enhancement layer. If the base layer is divided into multiple packets, the packets are often of similar importance. However, the enhancement layer can be divided into multiple packets with successively decreasing importance. Thus, for a real-time hierarchical image, this analytical result can be applied to a sequence of higher-importance base layers and successively less important enhancement layer packets.

When we transmit a sequence of multimedia progressive packets over MIMO channels due to significant differences in the bitstream, the tradeoffs between the space-time codes considered for encoding each packet are their target error rate and the efficiency of the spectrum . By utilizing DMT functions, we have analyzed the intersection of outage probability curves of space-time codes. The result shows that as long as there is an intersection of the outage probability, the efficiency of the spectrum increases and the crossing point at the SNR constantly increases while the crossing point at the outage probability decreases uniformly. In this paper, work extends to the more general case, i.e., the results can be applied to any space-time codes, receivers, and propagation channels with given DMT functions .

As a specific example, we considered D-BLAST with a group zero-forcing receiver, V-BLAST with an MMSE receiver, and OSTBC as well as spatial correlation Rayleigh and Rician fading channels as well as i.i.d. Showed monotonous behavior of intersections in Rayleigh fading channels. Based on them, we have derived an optimization method for D-BLAST, V-BLAST, and OSTBC for optimal space-time coding of a sequence of many progressive packets.

Numerical evaluation shows that PSNR performance is improved (almost 2dB at 34dB PSNR) when D-BLAST is introduced in addition to V-BLAST and OSTBC. This has motivated us to deal with optimal strategies for a variety of space-time codes than previously considered optimal strategies for V-BLAST and OSTBC. The evaluation shows that the computational complexity associated with optimal space-time coding without any PSNR degradation is exponentially reduced by use of the derived optimization method. In addition, it indicates that the PSNR performance averages for all possible sets of space-time codes are better when the derived optimization method is used, which on average is a good strategy for space-time coding of multimedia progressive sources.

Our analysis allows tradeoffs between time-space codes in terms of their target error rate and transmission data rate (i.e., spectrum efficiency), and an optimal strategy for progressive transmission is their target error rate and transmission Data rate. &Lt; / RTI &gt;

16 is a flowchart illustrating a method of transmitting a bitstream in a multi-antenna system according to an embodiment of the present invention.

And a plurality of packets obtained by packetizing the bit stream into a plurality of packets are encoded and modulated (S300). And coded and modulated according to the importance of the arranged packets. In the case where the arranged packets are arranged in descending order of importance from the order of importance, coding and modulation can be performed based on a relatively low coding order or a transmission data rate in the case of relatively high priority packets And allows coding and modulation to be performed based on a relatively high coding order or a transmission data rate in the case of packets with relatively low importance.

After step S300, the plurality of coded and modulated packets are simulated by combining at least two space-time coding schemes among a first space-time coding scheme, a second space-time coding scheme, and a third space-time coding scheme at step S302. Wherein the first space-time coding scheme corresponds to an OSTBC (Orthogonal Space Time Block Codes) scheme, the second space-time coding scheme corresponds to a D-BLAST (Diagonal-Bell Laboratories Layered Space Time) May correspond to a V-BLAST (Vertical-Bell Laboratories Layered Space-Time) method.

Wherein when the plurality of packets are composed of first through Nth (where N is a positive integer greater than 1) packets, the first packet through the I sequentially arranged I, where I is greater than 1 and N Space-time coding using the first space-time coding scheme and the second space-time coding scheme for sequentially sequentially arranged I + 1 to N packets, Can be simulated. In addition, when the plurality of packets are composed of first to Nth (where N is a positive integer greater than 1) packets, the first packet to the first packet sequentially arranged I 1) -th packet to K (where K is larger than I + 1 and smaller than N), and a second time-space coding method using the first space- Space-time coding using the second space-time coding scheme for the (K + 1) -th to (N + 1) -th packets arranged in a sequence, and space-time coding using the third space- Can be simulated.

Space-time coding is performed by combining at least two coding schemes among the first space-time coding scheme, the second space-time coding scheme, and the third space-time coding scheme sequentially from the order of high packet importance to the plurality of packets . Space-time coding may be performed for the plurality of packets in consideration of at least one of a target outage probability and a target bit error rate.

Wherein the step of simulating space time coding for the plurality of packets comprises:

(Where N is the number of packetized packets of the bit stream).

The details of step S302 are the same as those described in the bit stream transmission apparatus, and therefore, detailed description thereof will be omitted.

After step S302, optimum space-time coding is performed on the plurality of packets according to a simulation result of space time coding (S304). For a plurality of packets

The optimal space-time coding is determined from the simulated space-time coding by the number of times.

After step S304, the plurality of time-space coded packets are transmitted (S306). If it is transmitted to the time-space coded bit stream according to the OSTBC scheme, the receiver can receive the time-space coded bit stream according to the OSTBC scheme through a decorrelator. If the B-stream is transmitted to the space-time coded B-stream according to the D-BLAST scheme, the receiver can receive the space-time coded B-stream according to the D-BLAST scheme through a group zero forcing receiver. Also, if the V-BLAST scheme is used to transmit the space-time coded BIS stream, the receiving end can receive the space-time coded BIS stream according to the V-BLAST scheme through a group zero forcing receiver.

The methods according to the present invention can be implemented in the form of program instructions that can be executed through various computer means and recorded on a computer readable medium. The computer readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions recorded on the computer readable medium may be those specially designed and constructed for the present invention or may be available to those skilled in the computer software.

Examples of computer readable media include hardware devices that are specially configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those generated by a compiler, as well as 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 with at least one software module to perform the operations of the present invention, and vice versa.

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 invention as defined in the appended claims. It will be possible.

200: coding and modulation unit
210: space-time coding unit
220:

Claims (16)

1. A bit stream transmission apparatus in a multi-antenna system,
A coding and modulating unit for coding and modulating each of a plurality of packets obtained by packetizing the bit stream into a plurality of packets;
Simulation results of combining each of the plurality of packets with an OSTBC (Orthogonal Space Time Block Codes) scheme, a D-BLAST (Diagonal-Bell Laboratories Layered Space Time) scheme, and a V-BLAST (Vertical-Bell Laboratories Layered Space- A space-time coding unit that performs space-time coding in a space-time coding scheme satisfying a target outage probability of each of the plurality of packets with a minimum signal-to-noise ratio; And
And a transmitter for transmitting a plurality of space-time coded packets,
Wherein the space time coding unit arranges the plurality of packets in the order of the lowest target error rate, performs the simulation sequentially according to the order of the packets,
The OSTBC method and the D-BLAST method combination are applied first, and the D-BLAST method and the V-BLAST method are applied to the OSTBC method and the D-BLAST method, A bit stream transmission device that simulates only the combination. delete The apparatus of claim 1, wherein the space-
The method of claim 1, wherein when the plurality of packets are composed of first to Nth (where N is a positive integer greater than 1) packets, the sequentially arranged first to Ith packets, where I is greater than 1 and N Space-time coding is simulated using the OSTBC scheme for packets with a smaller positive integer, and time-space coding is simulated using the D-BLAST scheme for sequentially-arranged I + 1 to Nth packets Bit stream transmission device. The apparatus of claim 1, wherein the space-
Wherein when the plurality of packets are composed of first through Nth (where N is a positive integer greater than 1) packets, the first packet through the I sequentially arranged I, where I is greater than 1 and N 1 &lt; / RTI &gt; packets to K (where K is a positive integer greater than I + 1 and less than N) Space-time coding is simulated for the packets using the D-BLAST scheme, and time-space coding is simulated for the (K + 1) -th to N-th packets sequentially arranged using the V-BLAST scheme. Stream transmission device. delete delete The apparatus of claim 1, wherein the space-
For the plurality of packets

(Where N is the number of packetized packets of the bit stream). &Lt; / RTI &gt; The method according to claim 1,
A space-time coded bitstream according to the OSTBC scheme is received by a decorrelator at a receiving end, and a space-time coded bitstream according to the D-BLAST scheme is received by a group zero forcing receiver And a time-space coded bitstream according to the V-BLAST scheme is received by a minimum mean square error receiver (MMSE) receiver at a receiving end. A method for transmitting a bitstream in a multi-antenna system,
Coding and modulating each of a plurality of packets obtained by packetizing the bit stream into a plurality of packets;
Arranging the plurality of packets in order of decreasing target error rate;
Simulating each of the plurality of packets by combining at least two coding schemes among an OSTBC scheme, a D-BLAST scheme, and a V-BLAST scheme;
Performing space-time coding in a space-time coding scheme satisfying a target outage probability of each of the plurality of packets with a minimum signal-to-noise ratio according to a simulation result of space-time coding; And
And transmitting a plurality of space-time coded packets,
Wherein the simulating step sequentially performs the simulation according to the order in which the plurality of packets are listed,
BLAST scheme and the D-BLAST scheme are applied to the OSTBC scheme and the combination of the D-BLAST scheme and the D-BLAST scheme and the V-BLAST scheme, A method of transmitting a bitstream that simulates only a combination of methods. delete 10. The method of claim 9, wherein simulating space-time coding for the plurality of packets comprises:
Wherein when the plurality of packets are composed of first through Nth (where N is a positive integer greater than 1) packets, the first packet through the I sequentially arranged I, where I is greater than 1 and N Space-time coding is simulated using the OSTBC scheme for packets with a smaller positive integer, and time-space coding is simulated using the D-BLAST scheme for sequentially-arranged I + 1 to Nth packets Wherein the bitstream is transmitted to the base station. 10. The method of claim 9, wherein simulating space-time coding for the plurality of packets comprises:
Wherein when the plurality of packets are composed of first through Nth (where N is a positive integer greater than 1) packets, the first packet through the I sequentially arranged I, where I is greater than 1 and N 1 &lt; / RTI &gt; packets to K (where K is a positive integer greater than I + 1 and less than N) Space-time coding is simulated for the packets using the D-BLAST scheme, and time-space coding is simulated for the (K + 1) -th to N-th packets sequentially arranged using the V-BLAST scheme. Stream transfer method delete delete 10. The method of claim 9, wherein simulating space-time coding for the plurality of packets comprises:
For the plurality of packets

(Where N is a packetized number of bit streams). The method of claim 9,
A space-time coded bitstream according to the OSTBC scheme is received by a decorrelator at a receiving end, and a space-time coded bitstream according to the D-BLAST scheme is received by a group zero forcing receiver And a time-space coded bitstream according to the V-BLAST scheme is received by a minimum mean square error receiver (MMSE receiver) at a receiving end.

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