RU2722587C9 - Method of generating and breaking up a message text in information binary application layer packets - Google Patents

Abstract

FIELD: data processing.SUBSTANCE: method of generating and breaking up a message text based on use of a range of changes of transmitted parameters and their allowable accuracy, which consists in the fact that the length of the field for each parameter is determined by a natural number which characterizes the value of variation of said parameter in conditional units, which is the permissible accuracy of the parameter, fields for parameters in message text are placed in series, value of each parameter is transferred by its offset relative to minimum value in standard units, and formation and breaking up of message text is carried out by unified algorithms.EFFECT: achieved technical result of disclosed method of generating and breaking up message text is simplification and acceleration of development, generation and breaking up of extremely short texts of messages in binary protocols of application level by formation of optimal unified text structure of message based on data on range of changes and permissible accuracy of transmitted parameters using universal machine-oriented algorithms.1 cl

Description

The invention relates to the field of information messages generation and can be used for optimal automated generation and decomposition of the message text in information binary packages of the application level based on the available information about the range of changes and the permissible accuracy of the transmitted parameters.

When transmitting information messages, regardless of the chosen method of encoding and transmitting information, developers are faced with the task of developing application-level protocols. At the application level, in a packet of any protocol, a "container" part can be distinguished, the task of which is to bring the packet to the desired addressee and inform about the type of the message text, and the message text itself, the transmission of which is the goal of interaction between the sending and receiving sides.

The text of the message is a set of bytes, where, in accordance with the type of the message in binary form, information about predetermined transmitted parameters of various purposes is placed, for example, identifiers and addresses of the transmitting side, the time of message formation, indications of the object's speed, its location, and the state of sensors. In a binary protocol, for each of these parameters, the required number of bits must be allocated, which together form the structure of the message text. One of the main tasks of the developer is to define structures and allocate fields for transmitted parameters in accordance with the types of transmitted messages. In some cases, the number of bits to allocate is obvious. If, for example, it is necessary to transmit one of 14 possible commands, then it is enough to allocate 4 bits, on which any command in the form of a natural number can be placed in binary form, and there will still be a reserve for expansion to 16 commands. But the parameters in the initial state can be both fractional and negative, and in the general case they are expressed as a real number with a certain range of variation, while on the receiving side the parameter must be restored with the required accuracy. Binary protocols, as a rule, are used where the information transfer rate is critical, which is usually typical for transmissions over radio channels with relatively low reliability. In such cases, from the point of view of information transmission, one should strive to form the shortest possible text of the message, thereby increasing the information transmission rate and increasing the noise immunity and transmission reliability.

To save space in binary protocols, the transmitted parameter is often presented in the form of a natural number with the least significant bit (conventional unit) equal to the permissible error. The maximum value of this number, and hence the number of bits allocated for it, is determined by the range of the parameter change in conventional units. The fields of the transmitted parameters combined into a set of bytes form the structure of the message text. The procedures for the formation and decomposition of the message text are quite laborious, so developers and programmers try to place the fields in the package in the most convenient way for themselves with minimal splitting of bytes, which sometimes leads to unjustified expansion of the message text to the detriment of reliability and information transfer speed. Moreover, any addition or change to the protocol leads to significant software improvements. Meanwhile, if we take as a basis the continuous arrangement of fields in the package, and the parameters are packed according to uniform rules, the processes of forming and decomposing message texts can be fully automated. In this case, with changes in the protocol, the basic procedures will remain unchanged, and the developers will not even need to know explicitly the structure of the message text.

Of the known methods of forming the text of the message, the closest (prototype) is the method of forming navigation messages broadcast by satellites of the GLONASS system (Global satellite system GLONASS / Ed. By V.N. Kharisov, A.I. Perov, V.A. Boldin - M. : IPRZhR, 1998.). It can be noted that in the lines of each navigation frame (Navigation frame structure, pp. 147, 148), the parameters are transmitted as natural numbers in conventional units equal to the least significant bit (acceptable precision), the length of the fields of most of the parameters is determined by the minimum number of bits that allows the range of the parameter change in conventional units, and the fields themselves, in most cases, have no spaces. But these message rules are optional. For example, in the selected prototype the number of digits for satellite accelerations is excessive, and there are gaps in the lines of the navigation frame. The absence of uniform, unified rules for the formation of messages does not allow achieving automation of the procedures for their formation and disbandment.

The aim of the invention is to simplify and accelerate the development, formation and decomposition of extremely short message texts of binary protocols of the application level by forming the optimal unified structure of the message text based on the data on the range of changes and the permissible accuracy of the transmitted parameters using universal machine-oriented algorithms.

To achieve the goal, a universal, machine-oriented method of forming and decomposing the message text is proposed, based on the use of the range of changes in the transmitted parameters and their permissible accuracy, which consists in the fact that the length of the field for each parameter is determined by a natural number characterizing the magnitude of the change in this parameter in arbitrary units , representing the permissible accuracy of the parameter, the fields for the parameters in the message text are arranged sequentially, the value of each parameter is transmitted by its offset with respect to the minimum value in arbitrary units, and the formation and disbandment of any message text is carried out according to unified algorithms.

To implement the proposed method, it is necessary, based on the available information on the number of transmitted parameters (k), the boundaries of changes (L _i P _i ) of each i-th parameter a _i ( a _i , ∈ [L _i , P _i ]) and its permissible accuracy d _i automate processes:

- formation by the transmitting side of the text of the message with information about the current values of the parameters,

- disbanding by the receiving side of the test message with the restoration of the current parameters with the required accuracy in the usual form.

Before describing the algorithms, it is necessary to find some preliminary relationships.

Since for each parameter a _{i the} range of its variation is known: a _i ∈ [L _i , P _i ], then taking the specified accuracy d _i as a conventional unit (the price of the least significant digit), we can find the natural number n _i to be transmitted, expressing the parameter shift in conventional units relative to the left border (the specified precision and boundaries are set in the same units as the parameter). Taking into account rounding to an integer (round), the required natural number is determined by the formula:

необходимое для его размещения, можно найти, решив показательное уравнение 2^х-1=(P_i-L_i)/d_i и округлив результат до целого значения (ceil) в большую сторону:The maximum value of the number and takes on the parameter equal to the upper limit ( a _i = P _i ). Number of bits

necessary for its placement, can be found by solving the exponential equation 2 ^x -1 = (P _i -L _i ) / d _i and rounding the result to an integer value (ceil) upwards:

The total estimated number of bytes N required to form the message text with the number of parameters k, with continuous sequential filling of the bit fields, is found by the formula:

Let us now give a brief description of easily formalized algorithms for the formation and decoding of the message text.

Formation of the message text (array {b _j } _N ) by the transmitting side is carried out by sequential processing of each i-th parameter of the total number of k parameters { a _i } _k in the following order:

1. According to the formula (3), the number of bytes allocated for the current i-th parameter is determined

2. According to the formula (1), the natural number n _{i to} be transferred is determined.

3. For the first parameter (i = 1), the number of the first of the involved bytes and the beginning of the location of the parameter in this byte (offset) are taken equal to zero, for all other parameters (i> 1) the number of the first of the involved bytes and the beginning of the location of the parameter in it are determined taking into account the previous cycle (item 4 for the (i-1) -th parameter).

4. For the next parameter, the boundaries of its location are determined: the number of bytes where it is located, and the number of bits used in each involved byte.

5. For each of the involved bytes:

- define a mask for the current parameter (a byte in which all involved bits are assigned the value "1"),

- taking into account the value of the last involved byte of the previous cycle (for i> 1), the values of the current involved bytes b _j are found using the bit shift n _i and the bit logical operation "and" with the corresponding mask.

6. If the parameter is not the last (i <k), go to step 1.

7. If the last parameter (i = k), consider the process of forming the message text array {b _j } _N finished.

с заданной точностью, для чего должно выполняться условие:The formed message text is attached to the container part of the message, encoded and broadcast to the desired addressee or several addressees. On the receiving side, the message is decoded, the number of transmitted parameters (k), the boundaries of their changes (L _i P _i ) and the permissible accuracy d _{i are} determined by the packet type, and the array {b _j } _{N is} decomposed. The purpose of the disbandment is to restore the original parameters

with a given accuracy, for which the condition must be met:

The disbanding of the message text {b _j } _N by the receiving party is carried out by sequential processing of the attributes of each i-th of the total number of k parameters in the following order (when obtaining the structure, the same relations are used as during the formation process):

1. According to the formula (3), the number of bytes allocated for the current i-th parameter is determined

2. For the first parameter (i = 1) the number of the first of the involved bytes and the beginning of the location of the parameter in this byte are taken equal to zero, for all other parameters (i> 1) the number of the first of the involved bytes and the beginning of the location of the parameter in it are determined taking into account the previous cycle (item 3 for the (i-1) -zo parameter).

3. For the next parameter, the boundaries of its location are determined: the number of bytes where it is located and the number of bits used in the last used byte.

4. For each of the involved bytes for the current parameter:

- define his mask,

- determine the component of a natural number and „using the bit logical operation" and "with the corresponding mask and bitwise shift,

- summing up the next component, sequentially form a natural number, receiving after processing the last of the involved bytes the desired value n _i .

5. Transformations inverse to formula (1) restore the original parameter with a given accuracy:

6. If the parameter is not the last (i <k), go to step 1.

законченным.7. If the parameter is the last (i = k), consider the process of decomposition of the message text array and restoration with a given parameter accuracy

finished.

As follows from the algorithms of formation and decomposition, the structure of the message text is completely determined by the initial information on the range of changes and the permissible accuracy of the transmitted parameters, and knowing it explicitly is of interest only as a reference material. It should also be noted that when developing complex systems, the nomenclature of transmitted messages can be very large and the calculated number of bytes N (see formula (4)) can vary within wide limits. For the convenience of coding and transmission over a communication channel, the real length of the message text is often unified either for all messages or for a certain class of messages close in length. In this case, the calculated number of bytes N serves as a guideline for classifying and choosing the optimal message lengths. All unused bits are filled with zeros, while the procedures for forming and disbanding message texts remain unchanged.

Example.

The service transport monitoring system consists of a control center (DP) and vehicles (TS) interacting with it via VHF radio channels. In the normal mode, the DP sequentially polls the vehicle and receives navigation messages from them. Obviously, for noise immunity and a decrease in the polling cycle, when drawing up a protocol, one should strive to develop the shortest messages possible.

According to the terms of reference, the system must serve up to 500 vehicles. The controlled area (part of the Pskov region) is limited by coordinates (in the Gauss-Kruger coordinate system):

- along the X axis: 6356 km - 6424 km

- along the Y axis: 5564 km - 5604 km

Possible vehicle speed up to 160 km / h.

The main and most loaded navigation message should include: vehicle address, vehicle state (up to 16 values), its planned coordinates with an accuracy of 4 m, speed with an accuracy of 3 km / h, heading with an accuracy of 5 °.

Both the transmitting and receiving sides have the characteristics of the parameters corresponding to the type of navigation message: Parameters (k = 6):

-address ( a ₁ ): d ₁ = 1, L ₁ = 0, P ₁ = 499;

- state ( a ₂ ): d ₂ = 1, L ₂ = 0, P ₂ = 15;

- coordinate X ( a ₃ (km)): d ₃ = 0.004, L ₃ = 6356, P ₃ = 6424;

- Y coordinate ( a ₄ (km)): d ₄ = 0.004, L ₄ = 5564, P ₄ = 5604;

- speed ( a ₅ (km / h)): d ₅ = 3, L ₅ = 0, P ₅ = 160;

- course ( a ₆ (degree)): d ₆ = 5, L ₆ = 0, P ₆ = 355;

Both in the formation and in the decomposition of the message text, the lengths of the fields for the parameters are sequentially determined (see formula (3)) and the general structure of the packet:

Masks for each of the parameters take the following values:

- for the 1st parameter (bytes 1, 2 are involved): 255, 1;

- for the 2nd parameter (the 2nd byte is involved): 30;

- for the 3rd parameter (bytes 2, 3, 4 are involved): 224, 255, 15;

- for the 4th parameter (bytes 4, 5, 6 are involved): 240, 255, 3;

- for the 5th parameter (the 6th byte is involved): 252;

- for the 6th parameter (the 7th byte is involved): 127.

We assume that the parameters intended for transmission have the following meanings:

a ₁ = 356; a ₂ = 7; a ₃ = 6404.336; a ₄ = 5581.222; a ₅ = 87.6; a ₆ = 46.5;

After processing on the transmitting side, we get:

a) natural forms of parameters (1):

n ₁ = 356; n ₂ = 7; n ₃ = 12084; n ₄ = 4305; n ₅ = 29; n ₆ = 9;

b) bytes of the message text:

b ₁ = 100; b ₂ = 143; b ₃ = 230; b ₄ = 21;

b ₅ = 13; b ₆ = 117; b ₇ = 9.

After disbanding on the receiving side and using formula (5), we get:

The obtained values coincide with the initial parameters within the permissible accuracy.

The achievable technical result of the proposed method for the formation and decomposition of the message text is to simplify and accelerate the development, formation and decomposition of extremely short message texts in binary protocols of the application level by forming an optimal unified structure of the message text based on the data on the range of changes and the permissible accuracy of the transmitted parameters using universal machine tools. -oriented algorithms.

Claims (1)

A method of forming and decomposing a message text in information binary packages of the application level, in which the transmitted parameters are packed in the form of natural numbers in arbitrary units equal to the permissible accuracy of the transmitted parameter, characterized in that when forming and decomposing the message text, only data on permissible accuracy and range is used changes in the transmitted parameters, and the formation and decomposition of the message text is carried out according to uniform unified rules, according to which the value of each parameter is determined by its displacement with respect to the minimum value in conventional units, the length of the field allocated for the parameter is determined by a natural number characterizing the range of its change in conventional units, and the fields in the message text are strictly ordered.