WO2016144041A1

WO2016144041A1 - Packet encoding device and method

Info

Publication number: WO2016144041A1
Application number: PCT/KR2016/002122
Authority: WO
Inventors: 박홍원; 장석호; 신미수
Original assignee: 한국항공우주연구원
Priority date: 2015-03-09
Filing date: 2016-03-03
Publication date: 2016-09-15

Abstract

Provided is a device for encoding a plurality of packets in a multi-antenna system, the packet encoding device comprising: a processor for sequentially determining space time codes of the packets from subordinate packets for the plurality of transmitted packets such that an average throughput of the plurality of packets is maximized; and a transmission unit for transmitting the plurality of packets to an antenna.

Description

Packet encoding apparatus and method

It is associated with a packet encoding technique. More specifically, the present invention relates to a technique of determining a space-time code of a packet and encoding the optimal transmission capacity in a multi-antenna wireless communication system.

After dividing the hierarchical multimedia source into multiple packets, the number of possible cases of transmitting an independent spatiotemporal code to each packet is M ^Np .

In the above equation, M is the number of types of space-time codes that can be allocated, and Np is the number of packets. As described above, it is necessary to find the maximum throughput of the multimedia source among M ^Np possible cases. As shown in the above equation, as the number of packets increases, the number of assignable cases increases exponentially.

In order to optimize the packet transmission, since the transmission capacity is numerically calculated for all M ^Np assignable cases, the case having the maximum transmission capacity is selected, which requires a lot of computational complexity.

In an apparatus for encoding a plurality of packets in a multi-antenna system according to an embodiment, the apparatus sequentially orders from the descending priority packet for the plurality of transmitted packets such that an average transmission throughput of the plurality of packets is maximized. The processor may include a processor configured to determine a space time code of the packet, and a transmitter configured to transmit the plurality of packets to an antenna.

In the apparatus for encoding a plurality of packets in a multi-antenna system according to an embodiment, when the processor determines the space time code, the space time code may be sequentially determined from the last packet to the first packet. In the apparatus for encoding a plurality of packets in a multi-antenna system according to an embodiment, the average transmission capacity of the multimedia may be expressed using the data rate and the packet error rate of each packet. In an apparatus for encoding a plurality of packets in a multi-antenna system according to an embodiment, the space-time code may be associated with a wireless communication system of a multi-antenna. In an apparatus for encoding a plurality of packets in a multi-antenna system according to an embodiment, the plurality of packets may be associated with a hierarchical multimedia source. In an apparatus for encoding a plurality of packets in a multi-antenna system according to an embodiment, the multimedia source may be associated with a scalable video or a progressive image.

A method of encoding a plurality of packets in a multi-antenna system, the method comprising sequentially space-time code from the descending priority packet for the plurality of transmitted packets so that the average throughput of the plurality of packets to the maximum Determining, and transmitting the plurality of packets to an antenna.

A method of encoding a plurality of packets in a multi-antenna system, the method may further include determining the space-time code sequentially from the last packet to the first packet when determining the space-time code.

In the method of encoding a plurality of packets in a multi-antenna system, the average transmission capacity of the multimedia may further comprise the step of using the data rate and the packet error rate of each packet. In a method of encoding a plurality of packets in a multi-antenna system, the space-time code may further include a step associated with a multi-antenna wireless communication system. In a method of encoding a plurality of packets in a multi-antenna system, the plurality of packets may be associated with a hierarchical multimedia source.

1 is an exemplary diagram of a block diagram of a packet encoding apparatus according to an embodiment.

2 is an exemplary graph illustrating a packet error rate of a space time code according to an embodiment.

3 is an exemplary diagram illustrating a method of maximizing an average transmission capacity according to an embodiment.

4 is an exemplary graph illustrating an average transmission capacity according to a space time code according to an embodiment.

5 is a flowchart illustrating an algorithm for a packet encoding method, according to an embodiment.

6 is a flowchart illustrating an algorithm for a packet encoding method, according to another embodiment.

Specific structural or functional descriptions of the embodiments are disclosed for purposes of illustration only, and may be practiced in various forms. Accordingly, the embodiments are not limited to the specific disclosure, and the scope of the present specification includes changes, equivalents, or substitutes included in the technical idea.

Terms such as first or second may be used to describe various components, but such terms should be interpreted only for the purpose of distinguishing one component from another component. For example, 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.

When a component is referred to as being "connected" to another component, it should be understood that there may be a direct connection or connection to that other component, but there may be other components in between.

Singular expressions include plural expressions unless the context clearly indicates otherwise. As used herein, the terms "comprise" or "have" are intended to designate that the described feature, number, step, operation, component, part, or combination thereof exists, but includes one or more other features or numbers, It is to be understood that it does not exclude in advance the possibility of the presence or addition of steps, actions, components, parts 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. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art, and are not construed in ideal or excessively formal meanings unless expressly defined herein. Do not. Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings. Like reference numerals in the drawings denote like elements.

Referring to FIG. 1, the packet encoding apparatus 100 provided herein may include a processor 110 and a transmitter 120. The processor 110 may sequentially determine the space-time code of the packet from a lower priority packet to the plurality of transmitted packets such that an average throughput of the plurality of packets is maximized. The transmitter may transmit the plurality of packets to an antenna.

Due to the nature of hierarchical multimedia, one bit at a time is transmitted as a stream of data continuously transmitted through a serial communication line.In this case, when an error occurs in a packet transmitted at a higher priority, the overall packet validity is considered. Packets located behind the packet cannot be used for decoding even if transmitted without error. That is, in order to be transmitted without error up to a lower priority packet, it is essential that the priority packet is transmitted without error. Therefore, it is possible to optimize the transmission of multimedia sources by determining the space-time code from the packet in the lower priority to the space-time code determined independently for each packet, and determining the space-time code of the packet in the more important order sequentially or in reverse order. have. In the following, an example of transmitting a multimedia source consisting of four packets is provided for convenience of description, but the present invention is not limited thereto and may be equally applicable to the transmission of more packets. The concept of average throughput in transmitting four packets is shown as 310 in FIG. 3 and the following equation.

In the apparatus for encoding a plurality of packets in a multi-antenna system according to an embodiment, the average transmission capacity of the multimedia may be expressed using the data rate and the packet error rate of each packet. In the above equation, ATP is an abbreviation of average throughput, Ri (bits) can represent the data rate or packet size of each packet, and Pi corresponds to the packet error rate. The first term is for the number of cases where the first packet with a packet size of R1 is transmitted with a probability of (1-P1), but the second packet has an error with a probability of P2. Similarly, the second term is the first and second packets (R1 + R2) are sent, with the probability of (1-P1) and (1-P2), the first and second packets are sent, but the probability of P3 in the third packet. The number of cases where an error occurred. Similarly, the third and fourth terms are also calculated to calculate the average transmission capacity. In the space-time coding scheme used in a multiple antenna system (MIMO SYSTEM), as shown in Equation 1 above, the value of the overall average transmission capacity also varies according to which space-time code is determined for a packet. In the past, since the average transmission capacity had to be calculated for all cases of the space-time code to maximize, the processor was often overloaded. According to the packet encoding method provided herein, the overload can be prevented. Will be. However, since Ri and Pi in Equation 1 vary according to which packet and what space-time code is determined, and each Ri and Pi have a tradeoff, determine the space-time code that maximizes the overall average transmission capacity. It is not easy to do. Hereinafter, the trade-off relationship will be described.

In an apparatus for encoding a plurality of packets in a multi-antenna system according to an embodiment, the space-time code may be associated with a wireless communication system of a multi-antenna. In general, there is a trade-off between data rate and packet error rate in space-time coding schemes. In the present application, description will be made using space-time codes of OSTBC, D-STTD, and V-BLAST which are generally used. However, the invention presented herein is not limited to this and can be applied to all space time codes. In a 4 * 4 MIMO system having four transmit / receive antennas, a tradeoff between data rate and packet error rate of a space-time code is shown in Table 1, and SNR versus packet error rate per symbol is shown in FIG. 2.

In other words, if the data rate Ri is high, the packet error rate Pi is also high. Therefore, it is not easy to determine which space-time code is optimal for a particular packet. If three space-time codes such as OSTBC, D-STTD, and V-BLAST are allocated to the four packets illustrated above, the number of possible cases is 81. The space-time encoding technique provided by the present invention can significantly reduce the number of cases instead of the exhaustive search described above. This will be described in detail later with reference to FIG. 3.

In the apparatus for encoding a plurality of packets in a multi-antenna system according to an embodiment, when the processor determines the space time code, the space time code may be sequentially determined from the last packet to the first packet. By sequentially determining the space-time code from the last packet and performing the same process from the first packet, the number of cases can be drastically reduced compared to the conventional algorithm. Previously, although the number of packets and the space-time code increased exponentially, the number of cases can be reduced by the number of packets * the number of space-time codes. In order to learn more about the above method, when Equation 1 is bound to R4 and modified, it is the same as 320 of FIG. 3 and Equation 2 below.

After the modification as shown in Equation 2, it is possible to determine which of the various space time codes (three space time codes of OSTBC, D-STTD and V-BLAST) for the last packet (Equation 2). In Equation 2, only the variables related to the fourth packet are R4 and P4, and the values for the remaining packets are treated as constants. That is, since R4 and P4 are determined according to which space-time code is used for the fourth packet, the space-time code for maximizing ATP in the above equation can be determined.

The important point here is that when R4 and P4 are defined, R3, P3, R2, P2, R1, and P1 need not be determined yet. That is, the spatiotemporal code of the fourth packet maximizing ATP can be determined regardless of which spatiotemporal code is assigned to the first, second and third packets.

The equation can be modified in the same way to determine the sign of the next third packet. This is shown in Equation 3 below.

When the space-time code of the last packet is determined, it determines which space-time code is used for the preceding packet (the third packet in the above example). That is, in the state where R4 and P4 are determined by the space-time code determined in the previous step, the space-time code of the third packet maximizing the average transmission capacity can be determined. Also important here is that when R3 and P3 are determined, R2, P2, R1, and P1 do not have to be determined yet. Regardless of which space-time code is assigned to the first and second packets, that is, the space-time code and data rate for the first and second packets are treated constant and the space-time code of the third packet can be determined to maximize the average transmission capacity. have.

The equation can be modified in the same way to determine the sign of the next second packet. This is shown in Equation 4 below.

Again, it determines which space-time code is to be used for the preceding packet (the second packet in the example above). That is, in the state where R4, P4, R3, and P3 are determined by the space time code determined in the above steps, the space time code of the second packet maximizing the average transmission capacity is determined. Similarly, when defining R2 and P2, R1 and P1 do not have to be determined yet and can be treated as constants. That is, regardless of which space-time code is assigned to the first packet, the space-time code of the second packet maximizing the average transmission capacity may be determined. Once the space time code of the second packet is determined, the space time code of the first packet can be determined to maximize the average transmission capacity.

In an apparatus for encoding a plurality of packets in a multi-antenna system according to an embodiment, the plurality of packets may be associated with a hierarchical multimedia source. The multimedia source may be associated with scalable video or progressive image. Hierarchical multimedia sources may be associated with hierarchically encoded multimedia. Hierarchical coding is a coding technique based on a qualitative layer. The hierarchical encoding is a method in which the lowest layer has minimal information and the continuous layer is encoded so as to have more information in terms of quality. This compression scheme is effective in packet-switched networks where traffic streams with many resources are shared or delays and losses are expected. Due to the nature of the hierarchical multimedia, since the data is transmitted through the serial communication line one bit at a time, the burden on the processor can be reduced by applying the packet encoding method provided herein. Scalable Video Coding is the name for the Annex G extension of the H.264 / MPEG-4 AVC video compression standard. Scalable video coding enables the encoding of high quality video bit streams that include one or more sub bit streams, which can be low spatial resolution (small screen), low time resolution (low frame rate), or low quality. Can represent a video signal. The scalable video coding may be performed using the packet encoding apparatus of the present application to encode multimedia that can be used in digital standard television (SDTV) and digital multimedia broadcasting (DMB). Progressive image transmissioin refers to a method of progressively transmitting part of an image instead of all of the image information, and is effectively used for interactive image transmission with a user through a narrow channel such as a telephone line. Corresponds to the technique. The transmitted image data takes a different method according to various techniques of image encoding. Initially, a schematic form of an image may be expressed, and additional information may be transmitted to reconstruct an image of progressively improved image quality. Since the progressive image is also encoded and transmitted based on hierarchical multimedia, encoding may be performed using the packet encoding apparatus of the present application.

4 is a graph showing the transmission capacity of the space-time code when OSTBC, D-STTD, and V-BLAST are used alone or in a mixture on a 4 * 4 MIMO system. In OSTBC, D-STTD, and V-BLAST, there are sections in which the average transmission capacity is maximized in comparison to other space-time codes. Therefore, by determining the space-time code for a packet using all of OSTBC, D-STTD, and V-BLAST, the transmission capacity can be maximized.

For example, the number of cases in which three space time codes are allocated to 16 packets is 3 ¹⁶ . The results of applying exhaustive search and the packet encoding algorithm provided herein to compare the ATP and find the allocation that maximizes the possible 3 ¹⁶ cases are as follows. The same result can be obtained.

By using the method proposed here, the amount of computation can be reduced by comparing the average transmission capacity only for a total of 16x3 = 48 cases. That is, the present invention can perform encoding of optimization when transmitting scalable video or progressive image, which is a hierarchical multimedia source composed of several packets, in a wireless communication system. The amount of computation required to decide whether to apply the technique can be greatly reduced. In particular, since a large amount of computation is required to allocate an optimal spatio-temporal code in real-time in a situation where a large number of packets is required, the present application can greatly contribute to making an efficient real-time multimedia transmission system.

5 is a flowchart illustrating an algorithm for a packet encoding method, according to an embodiment. 6 is a flowchart illustrating an algorithm for a packet encoding method, according to another embodiment.

A packet encoding method according to an embodiment includes determining a space-time code of the packets sequentially from a lower priority packet to the plurality of transmitted packets so that an average transmission throughput of the plurality of packets is maximized. It may be 610. In addition, the packet encoding method of the present application may include transmitting the plurality of packets to the antenna (620). 5, the packet encoding method provided herein may be used in a process of hierarchically encoding multimedia. Due to the nature of hierarchical multimedia, one bit at a time is transmitted as a stream of data continuously transmitted through a serial communication line.In this case, when an error occurs in a packet transmitted at a higher priority, the overall packet validity is considered. Packets located behind the packet cannot be used for decoding even if transmitted without error. That is, in order to be transmitted without error up to a lower priority packet, it is essential that the priority packet is transmitted without error. Therefore, it is possible to optimize the transmission of multimedia sources by determining the space-time code from the packet in the lower priority to the space-time code determined independently for each packet, and determining the space-time code of the packet in the more important order sequentially or in reverse order. have.

As described above, the present application will use a method of determining the space-time code from the last packet to maximize the average throughput in transmitting n packets. The space-time code may correspond to the space-time code of OSTBC, D-STTD, V-BLAST, and the like, but this is merely an example and is not limited thereto.

In a method of encoding a plurality of packets in a multi-antenna system according to an embodiment, the average transmission capacity of the multimedia may be expressed by using a data rate and a packet error rate of each packet. In the space-time coding scheme used in a multiple antenna system (MIMO SYSTEM), the overall average transmission capacity depends on which space-time code is determined for a packet. In the related art, as described above, since the average transmission capacity had to be calculated for all cases of the space-time code, the processor was often overloaded, and according to the packet encoding method to be provided herein, It can be prevented. However, Ri (packet data rate) and Pi (packet error rate) vary depending on which packet determines which space-time code, and each of Ri and Pi has a tradeoff. It is not easy to determine the spatiotemporal code that leads to

In a method of encoding a plurality of packets in a multi-antenna system according to an embodiment, the space-time code may be associated with a wireless communication system of a multi-antenna. In general, there is a trade-off between data rate and packet error rate in space-time coding schemes. In other words, if the data rate Ri is high, the packet error rate Pi is also high. Therefore, it is not easy to determine which space-time code is optimal for a particular packet. For example, if you want to assign m space-time codes to n packets, the number of possible cases is m ⁿ . The space-time encoding technique provided by the present invention can significantly reduce the number of cases to m * n instead of the exhaustive search described above.

In the apparatus for encoding a plurality of packets in a multi-antenna system according to an embodiment, when the processor determines the space time code, the space time code may be sequentially determined from the last packet to the first packet. Referring to FIG. 5, in case of transmitting n packets, the space time code of the n th packet may be determined. At this time as well, the space-time code for maximizing the average transmission capacity is determined. When the space-time code of the n-th packet is determined, the space-time code of the n-th packet may be determined, and the same process may be performed until the first packet is continuously determined (503). By using the above method, the number of cases has been reduced by the number of packets * the number of time-space codes, although the number of packets and the time-space code previously increased exponentially. In this case, when determining the space time code, the space time code of other packets may be treated as a constant to maximize the average transmission capacity. When the space-time code of the packet is determined, it is checked whether the average transmission capacity is maximum (510). If the average transmission capacity is maximum, n packets are transmitted to the antenna (520). If the average transmission capacity is not maximum, the method of determining the space-time code from the last (nth) packet may be repeated. Through the feedback, optimal space-time code determination can be performed. That is, the present invention can perform optimal encoding when transmitting scalable video or progressive image, which is a hierarchical multimedia source composed of multiple packets, in a wireless communication system. The amount of computation required to decide whether to apply the technique can be greatly reduced.

In a method of encoding a plurality of packets in a multiple antenna system according to an embodiment, the plurality of packets may be associated with a hierarchical multimedia source. The multimedia source may be associated with scalable video or progressive image. Hierarchical multimedia sources may be associated with hierarchically encoded multimedia. Hierarchical coding is a coding technique based on a qualitative layer. The hierarchical encoding is a method in which the lowest layer has minimal information and the continuous layer is encoded so as to have more information in terms of quality. This compression scheme is effective in packet-switched networks where traffic streams with many resources are shared or delays and losses are expected. Due to the nature of the hierarchical multimedia, since the data is transmitted through the serial communication line one bit at a time, the burden on the processor can be reduced by applying the packet encoding method provided herein. Scalable Video Coding is the name for the Annex G extension of the H.264 / MPEG-4 AVC video compression standard. Scalable video coding enables the encoding of high quality video bit streams that include one or more sub bit streams, which can be low spatial resolution (small screen), low time resolution (low frame rate), or low quality. Can represent a video signal. The scalable video coding may be performed using the packet encoding apparatus of the present application to encode multimedia that can be used in digital standard television (SDTV) and digital multimedia broadcasting (DMB). Progressive image transmissioin refers to a method of progressively transmitting part of an image instead of all of the image information, and is effectively used for interactive image transmission with a user through a narrow channel such as a telephone line. Corresponds to the technique. The transmitted image data takes a different method according to various techniques of image encoding. Initially, a schematic form of an image may be expressed, and additional information may be transmitted to reconstruct an image of progressively improved image quality. Since the progressive image is also encoded and transmitted based on hierarchical multimedia, encoding may be performed using the packet encoding apparatus of the present application. Since a detailed description of the packet encoding method is the same as that of the packet encoding apparatus, a description thereof will be omitted.

The embodiments described above may be implemented as hardware components, software components, and / or combinations of hardware components and software components. For example, the devices, methods, and components described in the embodiments may include, for example, processors, controllers, arithmetic logic units (ALUs), digital signal processors, microcomputers, field programmable gates (FPGAs). It may be implemented using one or more general purpose or special purpose computers, such as an array, a programmable logic unit (PLU), a microprocessor, or any other device capable of executing and responding to instructions. The processing device may execute an operating system (OS) and one or more software applications running on the operating system. The processing device may also access, store, manipulate, process, and generate data in response to the execution of the software. For convenience of explanation, one processing device may be described as being used, but one of ordinary skill in the art will appreciate that the processing device includes a plurality of processing elements and / or a plurality of types of processing elements. It can be seen that it may include. For example, the processing device may include a plurality of processors or one processor and one controller. In addition, other processing configurations are possible, such as parallel processors.

The software may include a computer program, code, instructions, or a combination of one or more of the above, and configure the processing device to operate as desired, or process it independently or collectively. You can command the device. Software and / or data may be any type of machine, component, physical device, virtual equipment, computer storage medium or device in order to be interpreted by or to provide instructions or data to the processing device. Or may be permanently or temporarily embodied in a signal wave to be transmitted. The software may be distributed over networked computer systems so that they may be stored or executed in a distributed manner. Software and data may be stored on one or more computer readable recording media.

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

Although the embodiments have been described with reference to the accompanying drawings, those skilled in the art may apply various technical modifications and variations based on the above. For example, the described techniques may be performed in a different order than the described method, and / or components of the described systems, structures, devices, circuits, etc. may be combined or combined in a different form than the described method, or other components. Or even if replaced or substituted by equivalents, an appropriate result can be achieved.

Claims

In the apparatus for encoding a plurality of packets in a multi-antenna system,

A processor configured to sequentially determine a space-time code of the packet from a lower priority packet to the plurality of packets so that an average transmission throughput of the plurality of packets is maximized; And

It includes a transmission unit for transmitting the plurality of packets to the antenna

Packet encoding device.
The method of claim 1,

When the processor determines the space-time code, the processor sequentially determines the space-time code from the last packet to the first packet.

Packet encoding device.
The method of claim 1,

The average transmission capacity is expressed using the data rate and packet error rate of each packet.

Packet encoding device.
The method of claim 1,

The space-time code is associated with a wireless communication system of multiple antennas.

Packet encoding device.
The method of claim 1,

The plurality of packets is associated with a hierarchical multimedia source

Packet encoding device.
The method of claim 1,

The plurality of packets may be associated with a scalable video or a progressive image.

Packet encoding device.
In the method of encoding a plurality of packets in a multi-antenna system,

Determining a space-time code sequentially from a lower priority packet for the plurality of transmitted packets such that an average throughput of the plurality of packets is maximized; And

Transmitting the plurality of packets to an antenna

Packet encoding method.
The method of claim 7, wherein

Determining the space-time code sequentially from the last packet to the first packet when determining the space-time code

Packet encoding method.
The method of claim 7, wherein

The average transmission capacity further comprises the step of expressing using the data rate and packet error rate of each packet.

Packet encoding method.
The method of claim 7, wherein

The space-time code further comprising: being associated with a multi-antenna wireless communication system

Packet encoding method.
The method of claim 7, wherein

The plurality of packets is associated with a hierarchical multimedia source

Packet encoding method.
A computer-readable recording medium having recorded thereon a program for performing the packet encoding method according to any one of claims 7 to 11.