CN102629893B - Information sending method and device by multiple-description successive refinement coding - Google Patents

Abstract

The invention discloses an information sending method by multiple-description successive refinement coding. The information sending method is characterized by comprising the following steps: S1, mapping an information source into at least two descriptors according to the channel conditions of at least two multipath fading channels, wherein each descriptor is in one-one correspondence with a fading channel; S2, performing successive refinement coding on each descriptor to divide each descriptor into at least two layers; S3, expressing the operation of minimizing expectation distortion to be the operation of maximizing the sum of diversity gain and multiplexing gain, and solving the operation of maximizing the sum of diversity gain and multiplexing gain to obtain the channel coding rate and channel allocation parameters of each layer of each descriptor; and S4, sending at least two descriptors by respectively adopting the channel coding rate and channel allocation parameters of each layer of each descriptor through the corresponding fading channel of the descriptor. According to the invention, the channel allocation and the channel transmission rate on the subchannel after allocation are considered, so that the communication uncertainty and signal transmission distortion are reduced and the communication reliability is improved.

Description

Information sending method and device for multi-description hierarchical coding

Technical Field

The present invention relates to the field of information transmission technologies, and in particular, to an information sending method and apparatus for multiple description layered coding.

Background

In the field of information transmission technology, hierarchical Coding (SRC for short) and Multiple Description Coding (MDC for short) are two commonly used error-resistant technologies. SRC and MDC have their own advantages in different transmission conditions and application environments. The SRC generates video streams which can be adaptively adjusted in a wide code rate range, and can adapt to transmission problems caused by channel bandwidth fluctuation and heterogeneous receiving equipment. MDC is encoded using multiple encoders, each of which produces an independent source description, which can be viewed as a distorted source, with the distortion decreasing with increasing description. The MDC is mostly used in a point-to-point wireless communication scenario with a high packet loss rate, and can provide better robustness.

The existing information sending method is based on an SRC, an MDC or an encoding method combining the SRC and the MDC, the information sending method strictly follows the separation theorem of Shannon, the channel function and the information source function are separately designed, one or both of the channel function and the information source function are optimized, and then the channel and the information source are combined for information sending. For example, the existing SRC and MDC combined method only focuses on the allocation of source rate resources, i.e. only focuses on how the sources are layered, how different source descriptions are obtained, or the concatenation relationship of the above two, and does not allocate channels.

For a wired communication system, the information transmission methods of the information source part and the information channel part of the communication system are respectively optimally designed, so that the overall performance of the system is not influenced. However, in the case of a wireless communication system, since the channel quality varies with time due to fading and interference of a wireless channel, if the above-described information transmission methods for designing the source part and the channel part of the communication system respectively are still used, communication uncertainty and signal transmission distortion are caused, and reliability of communication is poor.

Disclosure of Invention

Technical problem to be solved

The technical problem to be solved by the invention is as follows: how to reduce the uncertainty of communication and signal transmission distortion and improve the reliability of communication.

(II) technical scheme

In order to solve the above technical problem, the present invention provides an information sending method of multi-description layered coding, which comprises the following steps:

s1: mapping an information source into at least two descriptors according to the channel states of at least two multipath fading channels, wherein each descriptor corresponds to one fading channel one by one;

s2: hierarchically coding each descriptor, and dividing each descriptor into at least two layers;

s3: expressing the operation of minimizing the expected distortion as the operation of the sum of the maximized diversity gain and the multiplexing gain, solving the operation of the sum of the maximized diversity gain and the multiplexing gain, and obtaining the channel coding rate and the channel distribution parameter of each layer of each descriptor; the manner in which the operation of minimizing the expected distortion is expressed as the operation of maximizing the sum of the diversity gain and the multiplexing gain is:

converting the operation of minimizing the expected distortion into:

<math> <mrow> <munder> <mi>max</mi> <mrow> <msup> <mi>r</mi> <mi>i</mi> </msup> <mo>,</mo> <msup> <mi>l</mi> <mi>i</mi> </msup> </mrow> </munder> <munder> <mi>min</mi> <mrow> <mn>0</mn> <mo>&le;</mo> <mi>j</mi> <mo>&le;</mo> <msub> <mi>n</mi> <mi>i</mi> </msub> </mrow> </munder> <mo>{</mo> <mi>d</mi> <mrow> <mo>(</mo> <msubsup> <mi>r</mi> <mrow> <mi>j</mi> <mo>+</mo> <mn>1</mn> </mrow> <mi>i</mi> </msubsup> <mo>)</mo> </mrow> <mo>+</mo> <mi>b</mi> <msubsup> <mi>&Sigma;</mi> <mrow> <mi>t</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>j</mi> </msubsup> <msubsup> <mi>l</mi> <mi>t</mi> <mi>i</mi> </msubsup> <msubsup> <mi>r</mi> <mi>t</mi> <mi>i</mi> </msubsup> <mo>}</mo> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>1</mn> <mo>)</mo> </mrow> </mrow> </math>

wherein max represents a maximization operation, min represents a minimization operation, d represents a diversity gain, b represents a bandwidth utilization rate, r represents a multiplexing gain, l represents a channel allocation parameter, i represents a descriptor number, j represents a layer number, n represents a total layer number of the descriptor, and t represents an intermediate variable for calculation;

s4: and respectively adopting the channel coding rate and the channel allocation parameter of each layer of each descriptor, and transmitting the at least two descriptors through a fading channel corresponding to the descriptor.

Wherein, the dividing of each descriptor into at least two layers in the step S2 includes:

each of the descriptors is sub-partitioned into at least two layers using direct partitioning, unequal error protection, and/or overlapping coding techniques.

Wherein, the solving the operation of the sum of the maximized diversity gain and the multiplexing gain in step S3 to obtain the channel coding rate and the channel allocation parameter of each layer of each descriptor includes:

s3.1: initializing channel allocation parameters, and allocating channel bandwidth for each layer of each descriptor according to the channel allocation parameters;

s3.2: according to the current channel distribution parameters, solving the operation of the sum of the maximized diversity gain and the multiplexing gain according to a formula (1) to obtain the multiplexing gain corresponding to each layer of each descriptor;

s3.3: according to the multiplexing gain corresponding to each layer of each descriptor, according to R_C= rlogSNR, obtaining a channel coding rate corresponding to each layer of each descriptor, wherein R_CRepresenting the channel coding rate, r the multiplexing gain, and SNR the received signal-to-noise ratio.

S3.4: and solving the operation of the sum of the maximized diversity gain and the multiplexing gain according to a formula (1) according to the multiplexing gain corresponding to each layer of each descriptor at present to obtain the channel distribution parameter corresponding to each layer of each descriptor.

Wherein, initializing the channel allocation parameter in step S3.1 makes the channel bandwidth allocated to each layer of the same descriptor the same.

Wherein, after the step S3.4 is executed, the method further includes repeatedly executing the steps S3.2 to S3.4 for several times to obtain the optimized channel coding rate and channel allocation parameter of each layer corresponding to each layer of each descriptor.

Wherein the step S4 includes:

transmitting the at least two descriptors through the fading channel corresponding to each descriptor respectively, wherein

Transmission rate ofN Bandwidth of sending each layer in each descriptor, R_CIndicating the channel coding rate, i indicating the descriptor number, j indicating the layer number, l indicating the channel allocation parameter, and N indicating the channel bandwidth of the descriptor.

The invention also provides a device for transmitting the information of the multi-description hierarchical coding, which comprises the following components:

a multiple description unit, configured to map a source into at least two descriptors according to channel states of more than one fading channel, where each descriptor corresponds to one fading channel;

a hierarchical coding unit, configured to perform hierarchical coding on each descriptor, and divide each descriptor into at least two layers;

the channel calculation unit is used for expressing the operation of minimizing the expected distortion as the operation of the sum of the maximized diversity gain and the multiplexing gain, solving the operation of the sum of the maximized diversity gain and the multiplexing gain and obtaining the channel coding rate and the channel distribution parameter of each layer of each descriptor; the manner in which the operation of minimizing the expected distortion is expressed as the operation of maximizing the sum of the diversity gain and the multiplexing gain is:

converting the operation of minimizing the expected distortion into:

<math> <mrow> <munder> <mi>max</mi> <mrow> <msup> <mi>r</mi> <mi>i</mi> </msup> <mo>,</mo> <msup> <mi>l</mi> <mi>i</mi> </msup> </mrow> </munder> <munder> <mi>min</mi> <mrow> <mn>0</mn> <mo>&le;</mo> <mi>j</mi> <mo>&le;</mo> <msub> <mi>n</mi> <mi>i</mi> </msub> </mrow> </munder> <mo>{</mo> <mi>d</mi> <mrow> <mo>(</mo> <msubsup> <mi>r</mi> <mrow> <mi>j</mi> <mo>+</mo> <mn>1</mn> </mrow> <mi>i</mi> </msubsup> <mo>)</mo> </mrow> <mo>+</mo> <mi>b</mi> <msubsup> <mi>&Sigma;</mi> <mrow> <mi>t</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>j</mi> </msubsup> <msubsup> <mi>l</mi> <mi>t</mi> <mi>i</mi> </msubsup> <msubsup> <mi>r</mi> <mi>t</mi> <mi>i</mi> </msubsup> <mo>}</mo> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>1</mn> <mo>)</mo> </mrow> </mrow> </math>

wherein max represents a maximization operation, min represents a minimization operation, d represents a diversity gain, b represents a bandwidth utilization rate, r represents a multiplexing gain, l represents a channel allocation parameter, i represents a descriptor number, j represents a layer number, n represents a total layer number of the descriptor, and t represents an intermediate variable for calculation;

and the sending unit is used for sending the at least two descriptors through a fading channel corresponding to the descriptors by respectively adopting the channel coding rate and the channel allocation parameter of each layer of each descriptor.

(III) advantageous effects

The information sending method and the information sending device comprehensively consider the information source part and the channel part during information sending, and optimize the channel, so that the information is sent in an optimal channel allocation mode according to the fading condition of the wireless channel, thereby reducing the communication uncertainty and the signal transmission distortion caused by the fading of the wireless channel and improving the communication reliability.

Drawings

Fig. 1 is a flowchart of an information sending method of multiple description hierarchical coding according to an embodiment of the present invention;

fig. 2 is a schematic diagram of a coding structure of a method for transmitting information by multiple description hierarchical coding according to an embodiment of the present invention;

FIG. 3 is a flow chart of another method for transmitting multiple description layered coding information according to an embodiment of the present invention;

fig. 4 is a schematic diagram of channel allocation of a method for transmitting information with multiple descriptions in hierarchical coding according to an embodiment of the present invention;

fig. 5 is a schematic structural diagram of an information transmitting apparatus with multiple descriptions layered coding according to an embodiment of the present invention.

Detailed Description

The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.

Fig. 1 is a flowchart of an information sending method of multiple description hierarchical coding according to the present embodiment. As shown in fig. 1, the method includes the following processes.

Step 101: according to the channel state of more than one multipath fading channel, the information source is mapped into at least two descriptors, and each descriptor corresponds to one fading channel.

Step 102: each descriptor is hierarchically encoded.

In this step, each descriptor is divided into at least two layers when hierarchically encoded.

Step 103: and expressing the operation of minimizing the expected distortion as the operation of maximizing the sum of the diversity gain and the multiplexing gain, solving the operation of maximizing the sum of the diversity gain and the multiplexing gain, and obtaining the channel coding rate and the channel allocation parameter of each layer of each descriptor.

Step 104: and respectively adopting the channel coding rate and the channel allocation parameter of each layer of each descriptor, and transmitting the at least two descriptors through a fading channel corresponding to the descriptor.

In this embodiment, a source is first mapped into a plurality of descriptors, then each descriptor is layered, then a channel coding rate and a channel allocation parameter of each layer of each descriptor are obtained by expressing an operation of minimizing an expected distortion as an operation of maximizing a sum of a diversity gain and a multiplexing gain, and one descriptor is transmitted in each fading channel according to the channel coding rate and the channel allocation parameter. Therefore, the information source part and the channel part are comprehensively considered during information transmission, and the channel is optimized, so that the information is transmitted in an optimal channel allocation mode according to the fading condition of the wireless channel, thereby reducing the communication uncertainty and the signal transmission distortion caused by the fading of the wireless channel and improving the reliability of a communication system.

Fig. 2 is a schematic diagram of an encoding structure according to an embodiment of the present invention. As shown in fig. 2, with this coding structure, a source is first mapped into multiple descriptors, each descriptor corresponding to a fading channel. In fig. 2, the number of descriptors is only two, and in practical applications, the number of descriptors is not limited. Then, each descriptor is divided into multiple layers. And then all layers corresponding to each descriptor are sent to the sink through a fading channel. And decoding the information sink by combining the information source and the information channel.

The following describes the information transmission method proposed by the present invention in detail by taking mapping a source into two descriptors as an example with reference to the coding structure shown in fig. 2. As shown in fig. 3, the method includes the following processes.

Step 301: according to the channel states of two multipath fading channels, a source is mapped into two descriptors, and each descriptor corresponds to one fading channel. In this step, the information source is subjected to multiple description coding, which may be specifically implemented by using an optimal coding transmission scheme.

In particular, the source sequence is denoted by s, with s¹And s²Two descriptors are shown separately. The multiple description encoder maps the source sequence s into two descriptors s¹And s²Two descriptors refer to two versions formed after source compression, and the encoding process can be expressed as follows:

φ_K:s[1,...,K]→{1,...,M₁}×{1,...,M₂}

wherein phi is_KRepresenting a multiple description encoder, K representing the number of symbols in the source sequence, M₁Representation descriptor s¹Number of symbols in, M₂Representation descriptor s²The number of symbols in (1).

Accordingly, the decoding of multiple description coding consists of 3 decoders, including: an independent decoder 1, an independent decoder 2 and a core decoder. The independent decoder 1 and the independent decoder 2 decode the two descriptors s respectively¹And s²Core decoder jointly decodes two descriptors s¹And s²The decoding process can be expressed as:

wherein,

it is shown that the individual decoders 1,

it is shown that the individual decoders 2 are,

which represents the core decoder, is shown,

representing the decoded information.

After obtaining the descriptors through the mapping, the source coding rate of the two descriptors is obtained as follows:

and

wherein R is_S1Representation descriptor s¹Source coding rate of R_S2Representation descriptor s²The source coding rate of.

The distortion factor of the multi-description coding of the step is as follows:

<math> <mrow> <msup> <mi>D</mi> <mi>i</mi> </msup> <mrow> <mo>(</mo> <mi>s</mi> <mo>,</mo> <mover> <mi>s</mi> <mo>^</mo> </mover> <mo>)</mo> </mrow> <mo>=</mo> <mfrac> <mn>1</mn> <mi>K</mi> </mfrac> <munderover> <mi>&Sigma;</mi> <mrow> <mi>k</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>K</mi> </munderover> <mi>d</mi> <mrow> <mo>(</mo> <mi>s</mi> <mo>[</mo> <mn>1</mn> <mo>,</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>,</mo> <mi>K</mi> <mo>]</mo> <mo>,</mo> <mover> <mi>s</mi> <mo>^</mo> </mover> <mo>[</mo> <mn>1</mn> <mo>,</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>,</mo> <mi>K</mi> <mo>]</mo> <mo>)</mo> </mrow> <mo>,</mo> </mrow> </math> i =0,1,2, wherein D represents the degree of distortion, $d(s,\hat{s})=({\left(s\right[1]-\hat{s}[1\left]\right)}^2+{\left(s\right[2]-\hat{s}[2\left]\right)}^2+...+{\left(s\right[K]-\hat{s}[K\left]\right)}^2{)}^{1/2}$ representing decoded informationEuclidean distance from original information s, where s represents the original information,

indicates decoded information, and i indicates a descriptor number.

Step 302: each descriptor is hierarchically encoded.

In this step, each descriptor is hierarchically encoded. For two descriptors s¹And s²And respectively carrying out layered coding.

In hierarchically encoding each descriptor, each descriptor is divided into at least two layers. Specifically, each descriptor may be partitioned into at least two layers, including: direct partitioning, unequal error protection, superposition coding techniques. The number of layers to be divided is not limited, and the number of layers of each descriptor may be the same or different. If the two descriptors are further divided into multi-layer code streams, n is respectively used₁And n₂Representation descriptor s¹And s²Wherein n is₁>1, and n₂>1. Descriptors s¹Obtaining after layering:

descriptors s²Obtaining after layering:

wherein

The superscript i of (a) represents the ith descriptor, i =1, 2; the subscript j represents the jth tier, j ∈ {1,2₁(n₂)}. The channel bandwidth of each descriptor is represented by N, the source orderThe total number of sources in a column is denoted by K and the bandwidth utilization is denoted by b, then b = N/K, requiring b>1。

For two descriptors s¹And s²The layers were separated. Specifically, the layered encoder may be divided into N layers, the channel bandwidth N is divided proportionally, and l is used for transmitting the channel bandwidth occupied by the j-th layer_jN represents 1>l_j>0. For descriptors s¹And s²Should satisfy respectively

With R_CIndicating the channel coding rate, the channel coding rate of each layer of the transport channel

Where the superscript i represents the ith descriptor, i =1, 2; the subscript j represents the jth tier, j ∈ {1,2₁(n₂)}. According to b = R_C/R_SThe relationship between the source coding rate and the channel coding rate can be obtained, where b represents the bandwidth utilization. With R_SRepresenting the source coding rate, layer j having a source coding rate of

The interruption probability is used for characterizing the interruption performance of the link, and the interruption probability of the j layer is expressed as

The information of the j layer is the enhancement information of the previous j-1 layer, and the information of the j layer can be obtained only if the decoding of the information of the previous j-1 layer is successful. The source distortion factor of the correct decoding of the front j layers is as follows:

where D denotes the distortion factor, t denotes the intermediate variable used for the calculation, the superscript i denotes the ith descriptor, the subscript j denotes the jth layer,

after step 302, the channel coding rate and channel allocation parameter for each layer of each descriptor are obtained by expressing the operation of minimizing the expected distortion as the operation of maximizing the sum of diversity gain and multiplexing gain, and solving the operation of maximizing the sum of diversity gain and multiplexing gain. Specifically, the following steps 303 to 304 may be included.

Step 303: and solving the minimum expected distortion to obtain the channel coding rate of each layer of each descriptor.

The present step specifically includes the following steps 1 to 4.

Step 1: the operation of minimizing the expected distortion is represented as an operation of maximizing the sum of the diversity gain and the multiplexing gain.

In particular, the amount of the solvent to be used,

is the interruption probability of the j-th layer

Where Pr represents the probability of occurrence of an event, and i (c) represents the channel capacity, that is, when the channel transmission rate is greater than the channel capacity, the transmission is interrupted and the receiving end cannot decode correctly. Under the constraint of source layered coding, satisfy

I.e., the channel transmission rate of the j-th layer information is less than the channel transmission rate of the j +1 layer, and the outage probability increases as the channel transmission rate increases, i.e.

Source ith descriptor divided into n_iLayer, the interruption probability of layer 0 is 0, n_iThe interruption probability of +1 layer is 1, i.e.

Expected distortion of the ith descriptor from the distortion level of each hierarchy of the descriptor

And the probability of interruption of the channel occupied by each hierarchical information, in EDⁱRepresents the expected distortion of the ith descriptor, namely:

<math> <mrow> <msup> <mi>ED</mi> <mi>i</mi> </msup> <mo>=</mo> <munderover> <mi>&Sigma;</mi> <mrow> <mi>j</mi> <mo>=</mo> <mn>0</mn> </mrow> <msub> <mi>n</mi> <mi>i</mi> </msub> </munderover> <mrow> <mo>(</mo> <msubsup> <mi>P</mi> <mi>out</mi> <mi>i</mi> </msubsup> <mrow> <mo>(</mo> <mi>j</mi> <mo>+</mo> <mn>1</mn> <mo>)</mo> </mrow> <mo>-</mo> <msubsup> <mi>P</mi> <mi>out</mi> <mi>i</mi> </msubsup> <mrow> <mo>(</mo> <mi>j</mi> <mo>)</mo> </mrow> <mo>)</mo> </mrow> <mo>&CenterDot;</mo> <msubsup> <mi>D</mi> <mi>j</mi> <mi>i</mi> </msubsup> <mo>=</mo> <munderover> <mi>&Sigma;</mi> <mrow> <mi>j</mi> <mo>=</mo> <mn>0</mn> </mrow> <msub> <mi>n</mi> <mi>i</mi> </msub> </munderover> <mrow> <mo>(</mo> <msubsup> <mi>P</mi> <mi>out</mi> <mi>i</mi> </msubsup> <mrow> <mo>(</mo> <mi>j</mi> <mo>+</mo> <mn>1</mn> <mo>)</mo> </mrow> <mo>-</mo> <msubsup> <mi>P</mi> <mi>out</mi> <mi>i</mi> </msubsup> <mrow> <mo>(</mo> <mi>j</mi> <mo>)</mo> </mrow> <mo>)</mo> </mrow> <mo>&CenterDot;</mo> <msup> <mn>2</mn> <mrow> <mo>-</mo> <mi>b</mi> <msubsup> <mi>&Sigma;</mi> <mrow> <mi>t</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>j</mi> </msubsup> <msubsup> <mi>l</mi> <mi>t</mi> <mi>i</mi> </msubsup> <msubsup> <mi>R</mi> <mi>Ct</mi> <mi>i</mi> </msubsup> </mrow> </msup> </mrow> </math>

when receiving a source, in order to minimize the expected distortion of the source, it is necessary to reasonably allocate a channel corresponding to each descriptor of the source, and each descriptor is further divided into a base layer and a plurality of enhancement layers. In the embodiment of the invention, each descriptor corresponds to one channel, and the transmission channels of a plurality of descriptors are independent from each other. The ith descriptor being divided into n_iLayer, then the channel of the descriptor transmission is also divided into n_iA sub-channel of

Represents the proportion of each subchannel, j =1,2_i，

j=1,2,...,n_i. And, the sum of all sub-channels conforms to the normalized characteristics of the channel, i.e.

Furthermore, according to the layering technique employed in the embodiment of the present invention, the rate relationship of each subchannel transmission is: the channel transmission rate of the j-th layer is smaller than that of the j + 1-th layer, i.e.In the embodiment of the invention, the channel allocation parameters and the transmission rate on the sub-channel are obtained by solving the minimum signal source expected distortion performance. The channel allocation parameter is the bandwidth proportion of each sub-channel occupied by each layerTo do so byAnd (4) showing. Channel transmission rate of

And (4) showing.

From the above analysis, the operation of minimizing the expected distortion can be simply summarized as the following operational equation:

$\underset{{R_C}^i,l^i}{\min }{\mathrm{ED}}^i$

s.t. <math> <mrow> <munderover> <mi>&Sigma;</mi> <mrow> <mi>j</mi> <mo>=</mo> <mn>1</mn> </mrow> <msub> <mi>n</mi> <mi>i</mi> </msub> </munderover> <msubsup> <mi>l</mi> <mi>j</mi> <mi>i</mi> </msubsup> <mo>=</mo> <mn>1</mn> </mrow> </math>

j=1,2,...,n_i

$0<R_{C1}^i<R_{C2}^i<...<R_{{\mathrm{Cn}}_i}^i$

where min represents the minimization operation. The minimization process expressed by the formula is nonlinear optimization, the complexity is high, the engineering solution is convenient, the nonlinear method is converted into a linear method for solution, and the specific conversion process is described below.

The embodiment of the invention is mainly applied to the modern mobile communication system, so the signal source expected distortion performance under the condition of high signal-to-noise ratio is considered by combining the characteristics of the modern mobile communication system. The operation of minimizing the expected distortion is converted into an operation of maximizing the sum of the diversity gain and the multiplexing gain of the system by determining the important determinant of the expected distortion of the source under the environment with high signal-to-noise ratio, namely:

<math> <mrow> <munder> <mi>max</mi> <mrow> <msup> <mi>r</mi> <mi>i</mi> </msup> <mo>,</mo> <msup> <mi>l</mi> <mi>i</mi> </msup> </mrow> </munder> <munder> <mi>min</mi> <mrow> <mn>0</mn> <mo>&le;</mo> <mi>j</mi> <mo>&le;</mo> <msub> <mi>n</mi> <mi>i</mi> </msub> </mrow> </munder> <mo>{</mo> <mi>d</mi> <mrow> <mo>(</mo> <msubsup> <mi>r</mi> <mrow> <mi>j</mi> <mo>+</mo> <mn>1</mn> </mrow> <mi>i</mi> </msubsup> <mo>)</mo> </mrow> <mo>+</mo> <mi>b</mi> <msubsup> <mi>&Sigma;</mi> <mrow> <mi>t</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>j</mi> </msubsup> <msubsup> <mi>l</mi> <mi>t</mi> <mi>i</mi> </msubsup> <msubsup> <mi>r</mi> <mi>t</mi> <mi>i</mi> </msubsup> <mo>}</mo> </mrow> </math>

wherein max represents a maximization operation, min represents a minimization operation, d represents a diversity gain, b represents a bandwidth utilization rate, r represents a multiplexing gain, r belongs to [0,1], l represents a channel allocation parameter, i represents a descriptor sequence number, j represents a layer sequence number, n represents a total layer number of the descriptor, and t represents an intermediate variable for calculation.

The multiplexing gain, channel coding rate and received signal-to-noise ratio have the following relations: r_C= rlogSNR where R_CRepresenting the channel coding rate and SNR representing the received signal-to-noise ratio.

In summary, in step 1, the operation of minimizing the expected distortion is converted into

And calculating, wherein max represents a maximization operation, min represents a minimization operation, d represents a diversity gain, b represents a bandwidth utilization rate, r represents a multiplexing gain, l represents a channel allocation parameter, i represents a descriptor number, j represents a layer number, n represents a total layer number of the descriptor, and t represents an intermediate variable for calculation. By this equivalent approximate conversion, the system design can be simplified.

Step 2: and equally distributing the channels to obtain initialized channel distribution parameters.

Specifically, assuming equal channel allocation, the channel allocation parameters in the case of equal channel allocation are taken as the preset channel allocation parameters, that is, in step 2, the preset channel allocation parameters are obtained by the following calculation formulaj=1,2,...,n_iIn the formula, in the presence of a catalyst,

j=1,2,...,n_iparameters are allocated for the initialized channel.

And 3, step 3: and solving the operation of the sum of the maximized diversity gain and the multiplexing gain according to the initialized channel distribution parameters to obtain the multiplexing gain corresponding to each layer of each descriptor.

In particular, channel allocation parameters are based on initialization

j=1,2,...,n_iSolving for <math> <mrow> <munder> <mi>max</mi> <mrow> <msup> <mi>r</mi> <mi>i</mi> </msup> <mo>,</mo> <msup> <mi>l</mi> <mi>i</mi> </msup> </mrow> </munder> <munder> <mi>min</mi> <mrow> <mn>0</mn> <mo>&le;</mo> <mi>j</mi> <mo>&le;</mo> <msub> <mi>n</mi> <mi>i</mi> </msub> </mrow> </munder> <mo>{</mo> <mi>d</mi> <mrow> <mo>(</mo> <msubsup> <mi>r</mi> <mrow> <mi>j</mi> <mo>+</mo> <mn>1</mn> </mrow> <mi>i</mi> </msubsup> <mo>)</mo> </mrow> <mo>+</mo> <mi>b</mi> <msubsup> <mi>&Sigma;</mi> <mrow> <mi>t</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>j</mi> </msubsup> <msubsup> <mi>l</mi> <mi>t</mi> <mi>i</mi> </msubsup> <msubsup> <mi>r</mi> <mi>t</mi> <mi>i</mi> </msubsup> <mo>}</mo> </mrow> </math> Calculating to obtain channel transmission rate parameter

The specific solving process comprises the following steps: will be provided with

j=1,2,...,n_iSubstitution into <math> <mrow> <mrow> <munder> <mi>max</mi> <mrow> <msup> <mi>r</mi> <mi>i</mi> </msup> <mo>,</mo> <msup> <mi>l</mi> <mi>i</mi> </msup> </mrow> </munder> <munder> <mi>min</mi> <mrow> <mn>0</mn> <mo>&le;</mo> <mi>j</mi> <mo>&le;</mo> <msub> <mi>n</mi> <mi>i</mi> </msub> </mrow> </munder> <mo>{</mo> <mi>d</mi> <mrow> <mo>(</mo> <msubsup> <mi>r</mi> <mrow> <mi>j</mi> <mo>+</mo> <mn>1</mn> </mrow> <mi>i</mi> </msubsup> <mo>)</mo> </mrow> <mo>+</mo> <mi>b</mi> <msubsup> <mi>&Sigma;</mi> <mrow> <mi>t</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>j</mi> </msubsup> <msubsup> <mi>l</mi> <mi>t</mi> <mi>i</mi> </msubsup> <msubsup> <mi>r</mi> <mi>t</mi> <mi>i</mi> </msubsup> <mo>}</mo> </mrow> <mo>,</mo> </mrow> </math> The following system of equations is obtained:

$\begin{array}{c}d\left(r_{n_i}^i\right)=b{l}_{n_i}^i{r}_{n_i}^i\\ d\left(r_{n_i-1}^i\right)=d\left(r_{n_i}^i\right)+b{l}_{n_i-1}^i{r}_{n_i-1}^i\\ ......\\ d\left(r_1^i\right)=d\left(r_2^i\right)+b{l}_1^i{r}_1^i\end{array}$

and is $d\left(r_j^i\right)=1-r_j^i,$ j=1,2,...,n_i

According to the above equation system, the multiplexing gain corresponding to each layer of each descriptor can be calculated as $r_1^i,r_2^i,...,r_{n_i}^i.$

And 4, step 4: and calculating the channel coding rate corresponding to each layer of each descriptor according to the multiplexing gain corresponding to each layer of each descriptor.

Specifically, in step 4, the rootAccording to the multiplexing gain corresponding to each layer of each descriptor, according to the calculation formula R_C= rlogSNR, obtaining channel coding rate corresponding to each layer of each descriptor

Wherein R is_CRepresenting the channel coding rate, r the multiplexing gain, and SNR the received signal-to-noise ratio.

Step 304: and solving the operation of maximizing the sum of the diversity gain and the multiplexing gain according to the multiplexing gain corresponding to each layer of the descriptor, and acquiring the optimized channel allocation parameter corresponding to each layer of each descriptor. The above steps being initialised

Further obtain by a double operation $R_{\mathrm{Cj}}^i.$

Further, such equal division as described above

Is certainly not optimal, and the present step is then using the already obtained

Then calculate the optimalAnd (6) sequentially iterating. Specifically, the multiplexing gain calculated in step 303 is used

Substituting the operation of maximizing the sum of the diversity gain and the multiplexing gain

Obtaining channel allocation parameters corresponding to each layer of each descriptor

j=1,2,...,n_i，i=1,2。

After step 304 is completed, the channel coding rate and channel allocation parameters corresponding to each layer of each descriptor can be obtained. In practical application, after the step 303 and the step 304 are executed once, the optimal value can be obtained by performing a plurality of iterative operations according to the step 303 and the step 304 and calculating

And

for example, after the first execution of step 304, the method may be performed according to the results obtained by the first execution of step 304

Step 303 is executed again, that is, the first time step 304 is executed

Substituting the operation of the sum of the maximum diversity gain and the multiplexing gain again <math> <mrow> <mrow> <munder> <mi>max</mi> <mrow> <msup> <mi>r</mi> <mi>i</mi> </msup> <mo>,</mo> <msup> <mi>l</mi> <mi>i</mi> </msup> </mrow> </munder> <munder> <mi>min</mi> <mrow> <mn>0</mn> <mo>&le;</mo> <mi>j</mi> <mo>&le;</mo> <msub> <mi>n</mi> <mi>i</mi> </msub> </mrow> </munder> <mo>{</mo> <mi>d</mi> <mrow> <mo>(</mo> <msubsup> <mi>r</mi> <mrow> <mi>j</mi> <mo>+</mo> <mn>1</mn> </mrow> <mi>i</mi> </msubsup> <mo>)</mo> </mrow> <mo>+</mo> <mi>b</mi> <msubsup> <mi>&Sigma;</mi> <mrow> <mi>t</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>j</mi> </msubsup> <msubsup> <mi>l</mi> <mi>t</mi> <mi>i</mi> </msubsup> <msubsup> <mi>r</mi> <mi>t</mi> <mi>i</mi> </msubsup> <mo>}</mo> </mrow> <mo>,</mo> </mrow> </math> By performing step 303 again, reacquire

Then according to the result obtained by executing step 303 again

Step 304 is executed, i.e. the one obtained by executing step 303 for the first time

Substituting the operation of the sum of the maximum diversity gain and the multiplexing gain again <math> <mrow> <mrow> <munder> <mi>max</mi> <mrow> <msup> <mi>r</mi> <mi>i</mi> </msup> <mo>,</mo> <msup> <mi>l</mi> <mi>i</mi> </msup> </mrow> </munder> <munder> <mi>min</mi> <mrow> <mn>0</mn> <mo>&le;</mo> <mi>j</mi> <mo>&le;</mo> <msub> <mi>n</mi> <mi>i</mi> </msub> </mrow> </munder> <mo>{</mo> <mi>d</mi> <mrow> <mo>(</mo> <msubsup> <mi>r</mi> <mrow> <mi>j</mi> <mo>+</mo> <mn>1</mn> </mrow> <mi>i</mi> </msubsup> <mo>)</mo> </mrow> <mo>+</mo> <mi>b</mi> <msubsup> <mi>&Sigma;</mi> <mrow> <mi>t</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>j</mi> </msubsup> <msubsup> <mi>l</mi> <mi>t</mi> <mi>i</mi> </msubsup> <msubsup> <mi>r</mi> <mi>t</mi> <mi>i</mi> </msubsup> <mo>}</mo> </mrow> <mo>,</mo> </mrow> </math> By performing step 304 again, the data is acquired again

According to the method, the iteration times are set to be less than 10 times according to the actual requirement of the communication system applied by the information sending method, and the optimal information can be finally obtained after the iteration of 10 times at most, namely, by repeatedly executing the step 303 and the step 304

And

fig. 4 is a schematic diagram of channel allocation in this embodiment. As shown in fig. 4, taking 2 descriptors as an example, the channel bandwidth of each descriptor is N, and the descriptor s¹Each layer of $s_1^1,{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="HDA0000148971830000022.png"\; state="\{\{state\}\}">s</figure-callout>}}_2^1,...,s_{n_1}^1$ Respectively has a bandwidth of $l_1^{1}N,{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="HDA0000148971830000022.png"\; state="\{\{state\}\}">l</figure-callout>}}_2^{1}N,...,l_{n_1}^{1}N,$ Descriptors s²Each layer of $s_1^2,{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="HDA0000148971830000022.png"\; state="\{\{state\}\}">s</figure-callout>}}_2^2,...,s_{{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="HDA0000148971830000022.png"\; state="\{\{state\}\}">n</figure-callout>}}_2}^2$ Respectively has a bandwidth of $l_1^{2}N,{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="HDA0000148971830000022.png"\; state="\{\{state\}\}">l</figure-callout>}}_2^{2}N,...,{\mathrm{<figure-callout\; id="2"\; label="l\; n"\; filenames="HDA0000148971830000022.png"\; state="\{\{state\}\}">l</figure-callout>}}_{n_{}}^{{}_2}N.$

Step 305: and respectively adopting the channel coding rate and the channel allocation parameter of each layer of each descriptor, and transmitting the at least two descriptors through a fading channel corresponding to the descriptor.

Specifically, at least two descriptors are respectively transmitted through fading channels corresponding to each descriptor, whereinTransmission rate of

Bandwidth of each descriptor, R_CRepresenting the channel coding rate, i represents a descriptorSequence number, j denotes a layer sequence number, l denotes a channel allocation parameter, and N denotes a channel bandwidth of a descriptor.

In the present embodiment, the channel coding rate and the channel allocation parameter for each layer of each descriptor are obtained by combining multiple description coding with layered coding and then by expressing an operation of minimizing an expected distortion as an operation of maximizing the sum of a diversity gain and a multiplexing gain. Therefore, the information source part and the channel part are comprehensively considered during information transmission, and the optimal channel allocation mode is adopted for transmission according to the fading condition of the wireless channel, so that the reliability of the communication system is improved.

Fig. 5 is a schematic structural diagram of an information transmitting apparatus with multiple description layers encoded according to an embodiment of the present invention. As shown in fig. 5, the information transmitting apparatus includes at least: a multiple description unit 51, a layered coding unit 52, a channel calculation unit 53, and a transmission unit 54.

The multiple description unit 51 is configured to map a source into at least two descriptors according to channel states of more than one fading channel, where each descriptor corresponds to one fading channel.

The hierarchical coding unit 52 is configured to perform hierarchical coding on each descriptor, and divide each descriptor into at least two layers.

The channel calculating unit 53 is configured to represent the operation of minimizing the expected distortion as an operation of maximizing the sum of the diversity gain and the multiplexing gain, solve the operation of maximizing the sum of the diversity gain and the multiplexing gain, and obtain the channel coding rate and the channel allocation parameter of each layer of each descriptor.

The transmitting unit 54 is configured to transmit at least two descriptors through a fading channel corresponding to each descriptor by using the channel coding rate and the channel allocation parameter of each layer of each descriptor.

On the basis of the above technical solution, specifically, the hierarchical coding unit 52 is specifically configured to partition each descriptor into at least two layers and perform hierarchical coding on each descriptor by using a direct partitioning and/or unequal error protection and/or an overlapping coding technique.

On the basis of the above technical solution, in particular, the channel calculating unit 53 is specifically configured to convert the operation of minimizing the expected distortion intoAnd calculating, wherein max represents a maximization operation, min represents a minimization operation, d represents a diversity gain, b represents a bandwidth utilization rate, r represents a multiplexing gain, l represents a channel allocation parameter, i represents a descriptor number, j represents a layer number, n represents a total layer number of the descriptor, and t represents an intermediate variable for calculation.

On the basis of the foregoing technical solution, specifically, the channel calculating unit 53 is further configured to equally allocate channels, obtain preset channel allocation parameters, solve an operation of a sum of a maximized diversity gain and a multiplexing gain according to the preset channel allocation parameters, obtain a multiplexing gain corresponding to each layer of each descriptor, and obtain a multiplexing gain corresponding to each layer of each descriptor according to R_C= rlogSNR, obtaining a channel coding rate corresponding to each layer of each descriptor, wherein R_CRepresenting the channel coding rate, r representing multiplexing gain, and SNR representing the received signal-to-noise ratio, solving the operation of maximizing the sum of diversity gain and multiplexing gain according to the multiplexing gain corresponding to each layer of the descriptor, and obtaining the channel allocation parameter corresponding to each layer of each descriptor.

Based on the above technical solution, in particular, the transmitting unit 54 is configured to transmit at least two descriptors through the fading channel corresponding to each descriptor respectively, whereinTransmission rate of

N Bandwidth of sending each layer in each descriptor, R_CDenotes the channel coding rate, i denotes the descriptor number, j denotes the layer number, l denotes the channelThe allocation parameter, N, denotes the channel bandwidth of the descriptor.

Specifically, the specific implementation manner of each constituent unit of the information sending apparatus in the above embodiment of the present invention may refer to the description of the specific process in the information method.

In the embodiment of the present invention, a multiple description unit, a hierarchical unit, and a hierarchical coding unit are used to combine a multiple description coding technique with a hierarchical coding technique, and then a channel calculation unit is used to obtain a channel coding rate and a channel allocation parameter for each layer of each descriptor by expressing an operation of minimizing an expected distortion as an operation of maximizing a sum of a diversity gain and a multiplexing gain. Therefore, the information transmitting device comprehensively considers the source part and the channel part during information transmission, and adopts an optimal channel allocation mode to transmit according to the fading condition of a wireless channel, thereby improving the reliability of a communication system.

The above embodiments are only for illustrating the invention and are not to be construed as limiting the invention, and those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention, therefore, all equivalent technical solutions also belong to the scope of the invention, and the scope of the invention is defined by the claims.

Claims (7)

1. An information sending method of multi-description hierarchical coding is characterized by comprising the following steps:

s1: mapping an information source into at least two descriptors according to the channel states of at least two multipath fading channels, wherein each descriptor corresponds to one fading channel one by one;

s2: hierarchically coding each descriptor, and dividing each descriptor into at least two layers;

s3: expressing the operation of minimizing the expected distortion as the operation of the sum of the maximized diversity gain and the multiplexing gain, solving the operation of the sum of the maximized diversity gain and the multiplexing gain, and obtaining the channel coding rate and the channel distribution parameter of each layer of each descriptor; the manner in which the operation of minimizing the expected distortion is expressed as the operation of maximizing the sum of the diversity gain and the multiplexing gain is:

converting the operation of minimizing the expected distortion into:

<math> <mrow> <munder> <mi>max</mi> <mrow> <msup> <mi>r</mi> <mi>i</mi> </msup> <mo>,</mo> <msup> <mi>l</mi> <mi>i</mi> </msup> </mrow> </munder> <munder> <mi>min</mi> <mrow> <mn>0</mn> <mo>&le;</mo> <mi>j</mi> <mo>&le;</mo> <msub> <mi>n</mi> <mi>i</mi> </msub> </mrow> </munder> <mo>{</mo> <mi>d</mi> <mrow> <mo>(</mo> <msubsup> <mi>r</mi> <mrow> <mi>j</mi> <mo>+</mo> <mn>1</mn> </mrow> <mi>i</mi> </msubsup> <mo>)</mo> </mrow> <mo>+</mo> <mi>b</mi> <msubsup> <mi>&Sigma;</mi> <mrow> <mi>t</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>j</mi> </msubsup> <msubsup> <mi>l</mi> <mi>t</mi> <mi>i</mi> </msubsup> <msubsup> <mi>r</mi> <mi>t</mi> <mi>i</mi> </msubsup> <mo>}</mo> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>1</mn> <mo>)</mo> </mrow> </mrow> </math>

wherein max represents a maximization operation, min represents a minimization operation, d represents a diversity gain, b represents a bandwidth utilization rate, r represents a multiplexing gain, l represents a channel allocation parameter, i represents a descriptor number, j represents a layer number, n represents a total layer number of the descriptor, and t represents an intermediate variable for calculation;

s4: and respectively adopting the channel coding rate and the channel allocation parameter of each layer of each descriptor, and transmitting the at least two descriptors through a fading channel corresponding to the descriptor.

2. The method for transmitting information through multiple description layered coding according to claim 1, wherein the step S2 for dividing each of the descriptors into at least two layers comprises:

each of the descriptors is sub-partitioned into at least two layers using direct partitioning, unequal error protection, and/or overlapping coding techniques.

3. The method for transmitting information through multiple description layered coding according to claim 1, wherein the step S3 of solving the operation of maximizing the sum of diversity gain and multiplexing gain to obtain the channel coding rate and the channel allocation parameter of each layer of each descriptor includes:

s3.1: initializing channel allocation parameters, and allocating channel bandwidth for each layer of each descriptor according to the channel allocation parameters;

s3.2: according to the current channel distribution parameters, solving the operation of the sum of the maximized diversity gain and the multiplexing gain according to a formula (1) to obtain the multiplexing gain corresponding to each layer of each descriptor;

s3.3: according to the multiplexing gain corresponding to each layer of each descriptor, according to R_C= rlogSNR, obtaining a channel coding rate corresponding to each layer of each descriptor, wherein R_CRepresenting the channel coding rate, r the multiplexing gain, and SNR the received signal-to-noise ratio;

s3.4: and solving the operation of the sum of the maximized diversity gain and the multiplexing gain according to a formula (1) according to the multiplexing gain corresponding to each layer of each descriptor at present to obtain the channel distribution parameter corresponding to each layer of each descriptor.

4. The method according to claim 3, wherein the step S3.1 initializes the channel allocation parameters so that the channel bandwidth allocated to each layer of the same descriptor is the same.

5. The method as claimed in claim 3, wherein the step S3.4 is further performed and then repeated several times, i.e. steps S3.2 to S3.4 are performed, so as to obtain the optimized channel coding rate and channel allocation parameter for each layer corresponding to each layer of each descriptor.

6. The method according to any one of claims 1 to 5, wherein the step S4 comprises:

transmitting the at least two descriptors through the fading channel corresponding to each descriptor respectively, wherein

Transmission rate of

N Bandwidth of sending each layer in each descriptor, R_CIndicating the channel coding rate, i indicating the descriptor number, j indicating the layer number, l indicating the channel allocation parameter, and N indicating the channel bandwidth of the descriptor.

7. An information transmitting apparatus for multiple description layered coding, comprising:

a multiple description unit, configured to map a source into at least two descriptors according to channel states of more than one fading channel, where each descriptor corresponds to one fading channel;

a hierarchical coding unit, configured to perform hierarchical coding on each descriptor, and divide each descriptor into at least two layers;

the channel calculation unit is used for expressing the operation of minimizing the expected distortion as the operation of the sum of the maximized diversity gain and the multiplexing gain, solving the operation of the sum of the maximized diversity gain and the multiplexing gain and obtaining the channel coding rate and the channel distribution parameter of each layer of each descriptor; the manner in which the operation of minimizing the expected distortion is expressed as the operation of maximizing the sum of the diversity gain and the multiplexing gain is:

converting the operation of minimizing the expected distortion into:

<math> <mrow> <munder> <mi>max</mi> <mrow> <msup> <mi>r</mi> <mi>i</mi> </msup> <mo>,</mo> <msup> <mi>l</mi> <mi>i</mi> </msup> </mrow> </munder> <munder> <mi>min</mi> <mrow> <mn>0</mn> <mo>&le;</mo> <mi>j</mi> <mo>&le;</mo> <msub> <mi>n</mi> <mi>i</mi> </msub> </mrow> </munder> <mo>{</mo> <mi>d</mi> <mrow> <mo>(</mo> <msubsup> <mi>r</mi> <mrow> <mi>j</mi> <mo>+</mo> <mn>1</mn> </mrow> <mi>i</mi> </msubsup> <mo>)</mo> </mrow> <mo>+</mo> <mi>b</mi> <msubsup> <mi>&Sigma;</mi> <mrow> <mi>t</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>j</mi> </msubsup> <msubsup> <mi>l</mi> <mi>t</mi> <mi>i</mi> </msubsup> <msubsup> <mi>r</mi> <mi>t</mi> <mi>i</mi> </msubsup> <mo>}</mo> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>1</mn> <mo>)</mo> </mrow> </mrow> </math>

wherein max represents a maximization operation, min represents a minimization operation, d represents a diversity gain, b represents a bandwidth utilization rate, r represents a multiplexing gain, l represents a channel allocation parameter, i represents a descriptor number, j represents a layer number, n represents a total layer number of the descriptor, and t represents an intermediate variable for calculation;

and the sending unit is used for sending the at least two descriptors through a fading channel corresponding to the descriptors by respectively adopting the channel coding rate and the channel allocation parameter of each layer of each descriptor.

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