KR101621004B1 - Adaptive modulation transmission control apparatus based on atd-ai model - Google Patents

Abstract

Disclosed is an adaptive modulation transmission control apparatus based on an adaptive transmission design for availability assurance using ITU (ATD-AI) model. In the present invention, the apparatus provides a calculation formula with respect to a ratio of an available signal to noise, based on receiving signal intensity, availability, and a distance value so as to be able to set an efficient and highly-reliable prior transmission amount with respect to a bandwidth by using the ATD-AI model. In addition, the apparatus is configured to conveniently set the prior transmission amount, satisfying a request fade margin and an adaptive transmission technique, by using the ratio of an available signal to noise. According to the present invention, the apparatus comprises: an adaptive modulation control unit; a plurality of packet grouping units; a switch; a plurality of modulation/demodulation units; and a dynamic mapping unit.

Description

[0001] The present invention relates to an ATD-AI model-based adaptive modulation transmission control apparatus,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an adaptive modulation transmission control apparatus, and more particularly, to an adaptive modulation transmission control apparatus based on an ATD-AI (Adaptive Transmission Design for Availability Assurance) model that can guarantee availability, bandwidth allocation, To an adaptive modulation transmission control apparatus.

Recently, a microwave wireless link transmission system has been improved to transmit data of a large capacity at a high speed in a stable and economical manner by maximizing efficiency. In particular, in the military, in order to cope with changes in the battleground environment to the future NCW (Network Centric Warfare), the PTP (Point-To-Point) and PTM (Point-To-Multi) network facilities, Microwave links are widely used. In addition to the economical efficiency of data transmission, reliability of the military long distance wireless communication based system is an important issue, and an improved transmission technology that can be applied by combining existing transmission methods is required in order to secure both economy and reliability.

Wireless transmission links suffer from signal distortion caused by fading and multi-path due to thermal noise and interference. Availability is generally used as a measure for designing networks with high quality reliability. Availability refers to the percentage of time that can be handled without a fault, despite problems or problems due to fading.

On the other hand, prediction of microwave radio links is an important factor in designing long distance links. The longer the distance, the higher the probability of occurrence of fading, and therefore it may be difficult to continuously guarantee a high-quality QoS (Quality of Service). In order to guarantee a high-quality wireless link continuously in a wireless link, consideration is required for a channel fading environment depending on a link distance.

In the conventional microwave radio link transmission system, fixed modulation is mainly used. Although the transmission speed does not change in the fixed modulation scheme, since the same fixed modulation scheme is applied even when the link distances are different from each other, the quality of the radio link can be changed due to an increase in the fading occurrence probability according to the link distance. That is, it is difficult to maintain high availability continuously. Adaptive Modulation (AM) technique has been proposed to improve this and to adapt to the variable radio link environment and to maintain high availability and high quality reliable network at all times. However, when the link distance is long and the fading occurrence time is long, there is a limit to guarantee QoS such as transmission delay due to variable transmission rate only by AM.

B. L. Agba, R. Morin, and G. Bergeron, "Comparison of microwave links prediction methods: Barnett-vigants vs. ITU models, in Proc. PIERS, pp. 788-792, Xi'an, China, Mar. 2010.

An object of the present invention is to provide an ATD-AI model-based adaptive modulation transmission control device capable of setting an efficient and reliable priority transmission amount in relation to a bandwidth based on the strength, availability, and distance value of a received signal using an ATD- .

According to another aspect of the present invention, there is provided an ATD-AI model-based adaptive modulation and transmission control apparatus for storing a profile of a microwave communication system, the link distance d, the bandwidth B, The ATD-AI model-based available signal-to-noise ratio (ASNR) is calculated in a predetermined manner by using the frequency f and the non-application P _u and the intensity RL of the received signal, An adaptive modulation controller for setting a priority transmission amount (C _p ) satisfying a requested fade margin (M _p ) and an adaptive transmission scheme by comparing an available signal-to-noise ratio (ASNR) with a signal-to-noise ratio (SNR) A plurality of packet grouping units for grouping a plurality of data packets received through a plurality of ports to generate a data packet group; A switch for transmitting the plurality of data packets, which are applied through a port selected according to control of the modulation control unit, among the plurality of ports to the plurality of packet grouping units; A plurality of modulation and demodulation units selectively activated in accordance with the control of the modulation control unit and modulated and transmitted according to the adaptive transmission scheme set by the adaptive modulation control unit, And a dynamic mapping unit for generating and transmitting the distributed data packet group by distributing the data packet group from the plurality of packet grouping units in response to the activated modulation and demodulation unit. .

Wherein the adaptive modulation control unit is adapted to store the profile including the requested availability, the center frequency f, the climate and topography factor C, the transmission power TP, the gain G and the loss L elements, part; A demand fade margin calculation unit for calculating the demand fade margin (M) from the link distance (d) and the required usability; A link budget calculator for analyzing the profile to calculate the received signal strength (RL); The ATD-AI model-based available signal-to-noise ratio (ASNR) is calculated from the bandwidth B, the received signal strength RL, the ratio P _u , the link distance d and the center frequency f. An ASNR calculation unit for calculating an ASNR; (ASNR) based on the calculated ATD-AI model based on a plurality of adaptive transmission schemes applicable to each of the plurality of adaptive transmission schemes to calculate a priority transmission amount satisfying the required fade margin (M) (C _p ) and a priority transmission amount setting unit for selecting the adaptive transmission scheme; A traffic attribute analyzer for analyzing an attribute of the data packet applied through the plurality of ports to determine the bandwidth (B); And a number of channels according to the bandwidth (B); And a control unit.

The ASNR calculation unit may calculate an available signal-to-noise ratio (ASNR) based on the ATD-AI model using Equation

(Where RL is the received signal strength in dBm, P _u is the ratio used and _p is the slope on the radio link path, ε _p = (receive antenna height - transmit antenna height) / d f is the center frequency (GHz) of the transmitted signal, d is the link distance (Km), and K is Boltzmann's constant of 1.37 * 10 ^-23 J / K. Difference value ").≪ / RTI >

The ASNR calculator calculates a difference value (? B) from the -3 dB bandwidth with respect to the bandwidth (B)

In accordance with the following equation:

Wherein the priority transmission amount setting unit sets the priority difference transmission scheme to a fixed transmission scheme when the ATN-AI model-based available signal-to-noise ratio (ASNR) is equal to or greater than the signal- .

Wherein the priority transmission amount setting unit determines whether the available signal-to-noise ratio (ASNR) based on the ATD-AI model is equal to or greater than the signal-to-noise ratio (SNR) of each of the plurality of adaptive transmission techniques, ASNR is equal to or greater than a signal-to-noise ratio (SNR) of each of the plurality of adaptive transmission schemes from the lowest-order transmission scheme to the highest-order transmission scheme.

The link budget calculation unit refers to the profile and calculates the received signal strength (RL) using a transmission power (TP), a gain (G), and a loss (L)

In accordance with the following equation:

And the switch selects a priority port always receiving a priority data packet corresponding to a priority transmission amount among the plurality of ports under the control of the adaptive modulation control unit.

Therefore, the ATD-AI model-based adaptive modulation and transmission control apparatus of the present invention can set an efficient and reliable priority transmission amount in relation to the bandwidth based on the strength, availability, and distance value of the received signal using the ATD-AI model And the available signal-to-noise ratios can be used to easily set the priority transmission amount and the adaptive transmission scheme satisfying the required fade margin.

FIG. 1 is a diagram illustrating the concept of an adaptive transmission scheme, illustrating the necessity of priority transmission.
FIG. 2 shows a microwave communication system to which an ATD-AI model-based adaptive modulation and transmission control apparatus according to an embodiment of the present invention is applied.
FIG. 3 shows a configuration of an adaptive modulation control unit for determining a transmission scheme of the ATD-AI model-based adaptive modulation and transmission control apparatus of FIG.
4 illustrates an ATD-AI model-based adaptive modulation transmission control method according to an embodiment of the present invention.
FIGS. 5 to 10 show simulation results for evaluating the performance of the ATD-AI model-based adaptive modulation transmission control method of the present invention.

In order to fully understand the present invention, operational advantages of the present invention, and objects achieved by the practice of the present invention, reference should be made to the accompanying drawings and the accompanying drawings which illustrate preferred embodiments of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to the preferred embodiments of the present invention with reference to the accompanying drawings. However, the present invention can be implemented in various different forms, and is not limited to the embodiments described. In order to clearly describe the present invention, parts that are not related to the description are omitted, and the same reference numerals in the drawings denote the same members.

Throughout the specification, when an element is referred to as "including" an element, it does not exclude other elements unless specifically stated to the contrary. The terms "part", "unit", "module", "block", and the like described in the specification mean units for processing at least one function or operation, And a combination of software.

FIG. 1 is a diagram illustrating the concept of an adaptive transmission scheme, illustrating the necessity of priority transmission.

In an ideal microwave communication system without a fault, the maximum value of the reception sensitivity, which indicates the strength of the reception signal, appears equal to the reception level. However, in the actual digital radio system, the intensity of the received signal can be significantly lowered as fading occurs due to various conditions such as a weather condition, as shown in (a). The overall fade margin of a microwave communication system must take into account the time rate of the probability of occurrence of faults that may be small, such as meteorological conditions.

It is desirable that the modulation scheme be changed when fading occurs and the modulation scheme should be changed to a low-order modulation scheme so that more robust modulation scheme is applied during fading. Low-order modulation techniques used when the wireless channel environment is poor may result in degraded performance due to reduced transmission, while ensuring high-quality transmission guarantees.

it can be predicted that the transmission traffic may be lost if the number of bits per symbol is high when fading occurs in (a), so it is desirable to utilize a lower modulation scheme, as shown in (b). However, the ratio of transmission time should be considered as the transmission amount is changed and transmitted in the same bandwidth.

If the adaptive modulation is applied without consideration of the transmission amount, the transmission amount is reduced because a low modulation technique is utilized at a time when the radio channel environment is bad. If the transmission amount is reduced, there is a problem that data to be transmitted essentially such as voice or real-time data may not be transmitted due to mixed data.

Accordingly, it is possible to classify and transmit the traffic of the data to be transmitted first and the data of the delayable data essential for the wireless channel environment, and to set the traffic of the data to be transmitted as the priority transmission amount. In FIG. 1 (c), it can be seen that the voice data is set as the priority transmission amount and is set to be transmitted with uniform traffic regardless of the fading change.

Here, the priority transmission amount means the amount of transmission that can be transmitted at all times. Therefore, if the criterion for the priority transmission amount is ensured by the availability, it is possible to overcome the restriction on the variable radio channel environment and optimize the wireless transmission effectively. That is, it can be confirmed that the priority transmission amount is guaranteed between the links of the microwave communication system.

Here, the modulation scheme for the variable modulation can be considered up to 1024QAM in QPSK, and an error may occur depending on each time the modulation scheme is changed and the number of switching times. Under deadly fading conditions, error-free switching is essential. Due to the configuration of priority traffic, performance degradation may occur during switching with low-order modulation techniques. However, a higher order modulation scheme with a larger number of bits per transmission symbol requires a higher signal-to-noise ratio (SNR). For example, a minimum SNR value of more than 30dB is required for 256QAM, and 15dB for QPSK. That is, the higher the order of the modulation technique, the smaller the fade margin is due to the increase of the reception sensitivity.

When switching with a higher modulation scheme, the transmission output is typically reduced as well as back off is required for linear output characteristics. This can lead to performance degradation by reducing fade margins, but with error-free switching it is possible to achieve the required fade margin in key traffic. And the benefits of low order modulation can be exploited in link design. However, in order to apply such a technique, it is necessary to consider the ratio of the time according to the strength and the availability of the received signal, the distance between links, and the probability considering priority transmission. When fading occurs, it can be predicted that transmission traffic may be lost if the number of bits per symbol is high. Therefore, when fading occurs, a lower modulation technique is utilized and a time The ratio should be considered.

FIG. 2 shows a microwave communication system to which an ATD-AI model-based adaptive modulation and transmission control apparatus according to an embodiment of the present invention is applied.

FIG. 2 is a diagram for explaining an example in which two nodes are linked in a microwave communication system. Each of the links includes a transmitting / receiving device. Each of the transceivers includes an adaptive modulation controller (AM), a switch (SW), a plurality of packet aggregation units (RAG), a dynamic mapping unit (DPM) and a plurality of modulation and demodulation units do.

First, the adaptive modulation controller (AM) derives an optimal modulation scheme that considers the fade margin change to guarantee the required usability, an adaptive transmission scheme that considers both the priority traffic and the optimal band, A plurality of packet grouping units (RAG), a dynamic mapping unit (DPM), and a plurality of modulation / demodulation units (MD) so that data can be transmitted according to the control information.

The switch SW selects some data packets among a plurality of data packets applied through the Ethernet port according to the adaptive transmission scheme set by the adaptive modulation controller AM and transmits the data packets to the plurality of packet grouping units RAG1, RAG2 to the packet grouping units RAG1 and RAG2 corresponding to the adaptive transmission scheme. In this case, a predetermined number of ports among the plurality of Ethernet ports are priority ports for receiving the priority data packet, and the switch SW is controlled by the modulation control unit (AM), regardless of the change of the adaptive transmission scheme, To the corresponding packet grouping unit (for example, RAG1) among the plurality of packet grouping units RAG1 and RAG2.

Each of the plurality of packet grouping units RAG1 and RAG2 groups the data packets supplied from the switch SW so that they can be bundled and transmitted. That is, each of the plurality of packet grouping units RAG1 and RAG2 forms a data packet group by grouping the packet signals input from the baseband port for transmission on the wireless channel.

At this time, at least one packet grouping unit RAG1 of the plurality of packet grouping units RAG1 and RAG2 is provided for the priority data packet so that the priority data packet is always received regardless of the change of the adaptive transmission scheme, And generates a ranking data packet group. The remaining packet grouping units RAG2 excluding the at least one packet grouping unit RAG1 for grouping the priority data packets receive data to be applied from the switch SW according to the adaptive transmission scheme set by the adaptive modulation controller AM, Packets can be grouped. The remaining packet grouping unit RAG2 may be inactivated when a data packet is not applied from the switch SW according to the set adaptive transmission scheme.

The dynamic mapping unit DPM receives the data packet group from each of the plurality of packet grouping units RAG1 and RAG2 and transmits the applied plurality of data packet groups to the adaptive modulation control unit AM among the plurality of modulation and demodulation units MD To the selected modulation and demodulation unit according to the set adaptive transmission scheme, that is, under the control of the AMC (AM) controller. That is, the dynamic mapping unit (DPM) distributes the grouped input data packet signals to a plurality of modulation and demodulation units (MD) in order to distribute the data packet signals over a plurality of radio channels.

Each of the plurality of modulation and demodulation units MD includes a modulation unit MOD and a demodulation unit DEM. The modulation unit MOD supplies the distributed data packet group applied by the dynamic mapping unit DPM to the adaptive modulation control unit AM ) According to the adaptive transmission scheme, and transmits the modulated signal through the wireless path. The demodulation unit (DEM) demodulates the modulated signal applied through the radio path according to the set adaptive transmission scheme, and transmits the distributed data packet group to the dynamic mapping unit (DPM).

At least one modulation and demodulation unit (MD) selected by the adaptive transmission scheme among the plurality of modulation and demodulation units (MD) receives the distributed data packet group from the dynamic mapping unit (DPM) MD) can be deactivated.

FIG. 3 shows a configuration of an adaptive modulation control unit for determining a transmission scheme of the ATD-AI model-based adaptive modulation and transmission control apparatus of FIG. 2, FIG. 4 illustrates an ATD- Control method.

The adaptive modulation controller AM includes a profile storage unit 110, a requested fade margin calculation unit 120, a link budget calculation unit 130, an ASNR calculation unit 140, a priority transmission amount calculation unit 150, An analysis unit 160, and a channel number setting unit 170.

The profile storage unit 110 stores the profile of the microwave communication system. In the profile, the inter-node link distance d and the types of modulation schemes (QPSK, 8QAM to 1024QAM in the present invention) that can be applied to the adaptive transmission scheme, the request availability designated in designing the microwave communication system, (C), transmission power (TP), gain (G), and loss (L)

The requested fade margin calculation unit 120 first analyzes the profile stored in the profile storage unit 110 to check the link distance d and the requested availability, and then, using the confirmed link distance d and the requested availability, The fade margin M is calculated (S11).

The link distance d represents a path distance of a channel that performs communication between a plurality of nodes performing communication. In the present invention, a plurality of nodes are nodes whose positions are fixed, 110).

On the other hand, the required usability required in the digital radio relay system can be applied based on the transmission quality specified by ITU-R as a performance target in the wireless transmission path. The ITU-R target values can be classified into three categories of high, middle, and local level, but it is assumed that the present invention applies to the high level. The use of a target ratio for a digital radio relay system on a link with a link distance (d) to establish an actual digital radio transmission link to form a portion of a high-grade circuit is described in ITU-R Rec. F.634-4, "Error performance objectives for real digitalradio-relay links forming part of the high-grade portion of international digital connections at a basic rate within an integrated services digital network, 1997. [67] RL Freeman & "Radio System Design for Telecommunications, John Wiley & Sons, Inc., pp. 155-162, 2007." (1) and (2).

In the present invention, it is assumed that the target availability in accordance with Equations (1) and (2) is stored in advance in the profile storage unit.

When the link distance d specified in the profile and the required usability are confirmed, the profile storage unit 110 calculates the link distance d and the required fade margin M corresponding to the required usability.

In order to calculate the required fade margin (M), the correlation between the usability and the fade margin must first be confirmed. The relationship between the availability of the microwave communication system and the fade margin is described in the prior art "B. L. Agba, R. Morin, and G. Bergeron," Comparison of microwave links prediction methods: Barnett-vigants vs. ITU models, "in Proc. PIERS, pp. 788-792, Xi'an, China, Mar. 2010."

The demand fade margin M, which is derived from the non-use (P _u (%)) of the predictive model (hereinafter ITU model) according to ITU-R P.530, is calculated as shown in equation (3).

(Where M denotes the fade margin, P _u denotes the non-application, ε _p is the slope on the radio link path, ε _p = (height of the receiving antenna - height of the transmitting antenna) / d, f is the center of the transmitted signal Frequency (GHz), d represents the link distance (Km), and K is the Boltzmann's constant, which is 1.37 * 10 ^-23 J / K.

When the required fade margin M is obtained, the link budget calculation unit 130 calculates a link budget of the microwave communication system model according to the link distance (S12).

The link budget identifies various parameters such as a communication system specification and a channel status for a link that is a communication path between nodes, and algebraically calculates an increase / decrease in signal power due to gain and loss factors. When the link distance is predefined in the wireless communication system in which the transmission frequency and the transmission power between two nodes and all the gains G and L are confirmed, the calculation unit 130 calculates the intensity . ≪ / RTI >

Since the link distance d is previously specified in the profile, the link budget calculation unit 130 calculates the transmission power (TP) in consideration of all gains G and losses L between two nodes in the radio link, And RL (Receive Level) according to Equation (4).

In Equation 4, the path loss L is calculated as Equation 5 in a free space model where a line of sight (LOS) environment is guaranteed between the transmitter and the receiver and there is no obstacle around the radio link.

(Where d is the link distance in km and f is the frequency in MHz).

The path loss value L according to the link distance d and the frequency f and the available transmission power TP and the antenna gain G are applied according to Equation 5 and the path loss value L ) To calculate the received signal strength RL for the radio link interval from Equation (4).

In addition to the received signal strength RL calculated by Equation (4), the link budget calculator 130 calculates the reception sensitivity R _th according to the modulation technique in the microwave communication system according to Equation (6).

(Where R _th represents the receiver sensitivity that varies according to the transmission technique in the adaptive transmission scheme, N _o is the thermal noise (dBm / Hz), B _n is the -3 dB bandwidth in n MHz channel bandwidth, NF is the noise figure (dB), and SNR is the target signal-to-noise ratio (dB) of the system (BER = 10 ^-n ).

In Equation (6), the value of the reception sensitivity R _th changes according to the bandwidth. Therefore, it is necessary to consider the bandwidth (B) for effective transmission of the AM scheme considering the fade margin change with respect to the link distance (d) and high-reliability QoS.

The received signal strength RL can be calculated according to Equation 4 in the link budget calculation unit 130 and the reception sensitivity R _th is calculated according to Equation 6. The fade margin can be calculated from the received signal strength RL) and the reception sensitivity ( _Rth ), it can be calculated by Equation (7).

The fade margin in equation (7) represents the fade margin calculated theoretically in the microwave communication system model separately from the required fade margin (M) in equation (3).

As shown in equation (7), fade margin has an inversely proportional relationship with the reception (R _th). As the modulation scheme is higher order modulation, a larger SNR is required, and the reception sensitivity (R _th ) increases as shown in Equation (6). As a result, the fade margin decreases with higher order modulation.

The ASNR calculation unit 140 may apply the Equation (7) to set the priority traffic setting transmission amount according to Equation (8).

Equation (8) means that the less the required fade margin (M) from the received signal strength value (RL) by substituting the fade margin requirements instead of fading margin (M) of (7) the reception sensitivity (R _th) or higher.

(9) can be obtained by substituting Equation (6) into the reception sensitivity (R _th ) in Equation (8) and sorting on the basis of the signal-to-noise ratio (SNR).

In the present invention, the available signal-to-noise ratio (ASNR) is set to Equation (9), which is based on the signal-to-noise ratio.

That is, the ASNR calculation unit 140 calculates an available signal-to-noise ratio (ASNR) as shown in Equation (10).

And the thermal noise (N ₀₎ is -174 (dBm / Hz) at room temperature in the equation (10), noise figure (NF) can be set to a common receive noise figure 3dB.

Therefore, equation (10) can be summarized by equation (11).

In Equation (11),? B is the difference value for the -3 dB bandwidth, and the relationship between the occupied bandwidth (B) and? B is set as shown in Equation (12).

Meanwhile, the ASNR calculation unit 140 may calculate the transmission capacity according to the modulation scheme in relation to the transmission capacity Rb and the symbol rate Rs for N waveforms as shown in Equation (13).

That is, the ASNR calculation unit 140 substitutes the received signal strength RL, the non-use purpose P _u , the link distance d, and the center frequency f in consideration of the bandwidth B in Equation (11) To-noise ratio (ASNR). Therefore, the available signal-to-noise ratio (ASNR) can be derived without directly receiving the receiving sensitivity from the link node receiving the signal.

The available signal-to-noise ratio (ASNR) is based on the ATD-AI (Adaptive Transmission Design for Availability Assurance) model for the adaptive transmission scheme design to guarantee availability using ITU model to be.

The priority transmission amount setting unit 150 preliminarily calculates the priority transmission amount R _b according to the modulation scheme and the bandwidth B in accordance with Equations 13 to 16 and stores it as shown in Table 1.

(Where m is the number of bits per symbol m = log ₂ N, for example N = 64 when the modulation scheme is 64QAM and N = 128 when 128QAM).

In Equation 13, the transmission capacity R _b is the theoretical data transmission capacity of the pre-modulation stage.

The bandwidth (B) can also be obtained by Equation (14).

(Where B denotes the occupied bandwidth and K (α) is recommended as a function of the roll-off factor (α) in ITU-R F. 1191 and f _CLK is the frequency .

The priority transmission amount C _p at the link distance d can be expressed by Equation (15) according to Equation (13).

(Where R _sn represents the symbol rate in n MHz channel bandwidth).

The symbol rate (R _sn ) in the n MHz channel bandwidth of Equation (15) can be calculated by Equation (16).

Wherein R _s30, R _s40, R _s26 refers to the symbol rate (R _sn) for each of the channel bandwidth 30 (MHz), 40 (MHz ), 56 (MHz). In Equation 15, m is m = log ₂ N as the number of bits per symbol, as in Equation 13. In the present invention, it is assumed that the adaptive transmission scheme can use up to 1024 QAM from QPSK. Appears as a natural number from 2 to 10.

In Table 1, SNR8Q is the SNR value at the time of 8QAM modulation, and SNR16Q ... SNR1024Q is also the same.

Then, the priority transmission amount setting unit 150 substitutes the available signal-to-noise ratio (ASNR) calculated by the ASNR calculation unit 140 into Table 1, and outputs the signal-to-noise ratio in the maximum difference transmission scheme in which the available signal- (SNR _Max.n-QAM ) (S13). In the present invention, since the maximum difference transmission scheme is set to be 1024 QAM, it is determined whether the available signal-to-noise ratio (ASNR) is _equal to or higher than the signal-to-noise ratio (SNR _1024Q ) in the 1024 QAM modulation technique.

Ten thousand and one available signal-to-noise ratio (ASNR) the maximum difference is sent a signal-to-noise ratio (SNR _Max.n-QAM) or higher in the technique, the reception can also meet the required fade margin (M) up to primary transfer technique sensitivity (R _th) Can be obtained. Accordingly, the priority transmission amount setting unit 150 sets the fixed transmission scheme to a maximum difference transmission scheme (here, 1024 QAM modulation scheme) (S15). The traffic attribute analysis unit 160 and the channel number setting unit 170 determine the bandwidth B and the number of channels in the fixed modulation scheme, respectively (S16).

On the other hand, if the available signal-to-noise ratio (ASNR) is less than the signal-to-noise ratio (SNR _Max.n-QAM ) in the maximum difference transmission scheme, the priority transmission amount setting unit 150 corresponds to the available signal- And sets a priority transmission amount corresponding to the identified lowest difference transmission scheme (S17).

In Table 1, the priority transmission amount can be calculated by confirming the number of bits per symbol (m) corresponding to the QAM modulation technique and multiplying the symbol rate (R _sn ) corresponding to the bandwidth. The maximum modulation scheme does not need to be set separately, but the highest available differential transmission scheme (here, 1024 QAM modulation scheme) is applied.

On the other hand, if the channel environment in the wireless transmission link becomes poor due to fading, the traffic attribute analysis unit 160 analyzes the traffic attribute so as to be able to compensate for link quality degradation through adaptive modulation based priority traffic transmission (S18 ). The traffic attribute analyzer 160 sets the amount of transmission based on the priority traffic attribute for guaranteeing the availability and sets the attribute of the transmission traffic at the minimum transmission amount and the maximum transmission amount through the existing bandwidth or the available bandwidth allocation considering the frequency resource And set the general traffic transmission amount.

The priority traffic transmission amount and the general traffic transmission amount by the priority traffic attribute are calculated as a formula of the ratio of the priority transmission capacity Rp to the average transmission capacity (Ra) using the link distance, availability and AM (S21).

When the priority transmission capacity ratio Ratio is calculated according to Equation 17, the traffic attribute analysis unit 160 reflects the attributes of the transmission traffic at the minimum transmission amount and the maximum transmission amount based on the calculated priority transmission capacity ratio (Ratio) Set the amount of general traffic to be transmitted.

Then, the traffic attribute analyzer 160 sets an adaptive transmission scheme according to the analyzed traffic attribute (S19). In this case, the adaptive transmission scheme is selected from among the modulation schemes among the minimum difference transmission scheme identified by the priority transmission scheme setting unit 150, and a maximum difference transmission scheme (here, 1024 QAM modulation scheme) usable.

Thereafter, the channel number setting unit 170 sets the number of channels to be subjected to distributed transmission according to the modulation scheme selected by the traffic attribute analyzer 160 (S20).

The channel number setting unit 170 determines whether the transmission amount of the entire channel is equal to or greater than the transmission amount to be transmitted and the signal-to-interference ratio (C / I) for each channel is equal to or greater than a predetermined protection ratio (S21). If it is determined that the transmission amount of the entire set channel is equal to or greater than the transmission amount to be transmitted and the signal-to-interference ratio (C / I) per channel is equal to or higher than the protection ratio, the selected modulation technique, channel number and priority transmission amount are stored.

However, if the transmission amount of the entire set channel is less than the transmission amount to be transmitted, or if the channel-specific signal-to-interference ratio (C / I) is less than the protection ratio, the available signal-to-noise ratio (ASNR) is calculated again (S13).

FIGS. 5 to 10 show simulation results for evaluating the performance of the ATD-AI model-based adaptive modulation transmission control method of the present invention.

The simulation conditions utilized in FIGS. 5 to 10 are shown in Table 2.

In order to evaluate the performance of the proposed method, simulation based on MatLab was performed using the parameters in Table 2 through operations based on FIG. 1 and Equations 11 and 15. In order to analyze the performance, the parameter values of the applicable device for the military microwave communication distance were inputted, and simulation was performed through the simulation to analyze the ASNR, transmission amount,

In the proposed Equation (11), the requirement ratio is calculated for each distance in Equation (2). Table 3 assumes that the received signal strength (RL) is -35 dBm and the SNR (BER = 10E -6)) were based on the values given in ITU-R F.1101.

Table 3 shows the calculation results of distance and maximum transmission distance for priority transmission.

The amount of transmission can be varied by Guard frame, QoS parameters, data compression transmission, and so on.

It is possible to select the minimum QAM and the maximum QAM considering the bandwidth to guarantee the required usability.

The larger the bandwidth, the lower the transmission efficiency over long distances. These results show that the difference in ASNR values depending on the bandwidth affects the bit number selection per symbol to be transmitted.

In case of fixed modulation depending on the distance, the usability may vary, and it is shown that the number of transmission bits per symbol is required to be considered for long distance when variable modulation is applied.

Diversity method is not applied. Therefore, when diversity method is applied in case of actual long distance, it is more improved than required usability.

When the diversity scheme is applied, the requested availability can be expressed by Equation (18).

(Where U _R denotes the demand ratio for the diversity path, U _d denotes the unidirectional ratio for the diversity path, and I _d denotes the diversity improvement ratio).

In the case of applying the diversity scheme to the present invention, the unidirectional ratio U _d for the diversity path of Equation 18 can be applied by replacing the non-use ratio P _u (%) of Equation 3. However, priority of guarantee always higher than demand availability

If it is intended to transmit rank traffic, the diversity scheme may be applied after the diversity scheme is not considered.

FIG. 5 shows a ratio application (P _u ) change for three bandwidths at the minimum QAM and maximum QAM at a link distance of 100 km. The priority traffic setting and transmission design according to the adaptive modulation-based distance are required to guarantee the availability. It can be seen that the QAM modulation with a large number of bits per symbol and the non-application increase with increasing bandwidth.

Also, the larger the bandwidth, the weaker the transmission efficiency over long distances. These results show that the difference in ASNR values depending on the bandwidth affects the bit number selection per symbol to be transmitted.

In case of fixed modulation depending on the distance, the usability may change, and the application of adaptive modulation shows that the number of transmission bits per symbol needs to be considered for longer range. Diversity scheme is not applied. Therefore, when the diversity scheme is applied to the long distance, it can be more improved than the required usability.

For the ASNR f (d) value when the distance is d, it can be confirmed that the modulation scheme n-QAM satisfies the priority transmission basic design condition more than the SNR value in n-QAM.

Based on this value, we can see that it is possible to design the modulation scheme that guarantees usability through the proposed model in the link with distance (d).

In the case of applying the proposed ATD-AI model, it is shown that the minimum SNR value of QAM MOD and BER = 10E-6 at 30 MHz, 40 MHz, and 56 MHz bandwidth is decreased by the adaptive modulation based transmission scheme at longer distances. It is confirmed that the transmission performance can be improved more efficiently in the wireless environment through the adaptive modulation transmission scheme of the lowest QAM MOD and the maximum QAM MOD.

The transmission capacity simulation of FIG. 6 is based on the AM scheme using the present invention at each distance, and is based on a Priority Capacity corresponding to the lowest QAM. Herein, the modulation scheme in which 10 bits are transmitted per symbol of the maximum QAM (Average Capacity) (Fixed Modulation) and the environment which is operated with fixed modulation.

6 shows simulation results for bandwidths of 30 MHz, 40 MHz, and 56 MHz. The total transmission amount to be transmitted according to the distance should be smaller than the average transmission amount and the effective transmission can be achieved through the priority transmission amount that satisfies the request usability. Even if the average transmission amount is long, the difference in priority transmission amount is smaller as the bandwidth is smaller, and the transmission efficiency is higher even if the difference is caused according to the received signal strength.

FIGS. 7 and 8 show a simulation result of the optimal transmission rate per link distance.

FIG. 7 is a graph showing the relationship between the distance of the optimal transmission rate for the lowest QAM MOD selected based on the availability criterion, the ATD-AI model of the present invention and the intensity (RL) of the received signal at a bandwidth of 30, 40, FIG. 8 shows simulation results of the optimum transmission amount ratio for the minimum QAM MOD determined based on the availability criterion, with the intensity (RL) of the received signal being -40 dBm.

As shown in FIGS. 7 and 8, even if there is a difference in the intensity RL of the received signal according to the distance d, the optimum transmission amount ratio is larger and the transmission efficiency is higher as the bandwidth is smaller. For example, two bandwidths of 30 MHz than one 56 MHz bandwidth show more optimal throughput and greater reliability. This characteristic can be used as a design basis that has an important influence on the determination of the optimal bandwidth and the number of channels.

FIGS. 9 and 10 illustrate the availability change of the ATD-AI model applied modulation transmission control technique for each link distance.

FIG. 9 is a graph illustrating a simulation result assuming that the received signal strength RL is -35 dBm as in FIG. 7, and FIG. 10 is a graph illustrating simulation results of a case where the received signal strength RL is -40 dBm . FIGS. 9 and 10 illustrate the priority transmission and the availability of the fixed 128QAM transmission according to the modulation technique of the present invention, as compared with the required availability according to the distance. As shown in FIGS. 9 and 10, when the adaptive transmission scheme according to the present invention is applied, it can be seen that the demand ratio maintains a good result value below the usage according to the distance.

The method according to the present invention can be implemented as a computer-readable code on a computer-readable recording medium. A computer-readable recording medium includes all kinds of recording apparatuses in which data that can be read by a computer system is stored. Examples of the recording medium include a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, and the like, and a carrier wave (for example, transmission via the Internet). The computer-readable recording medium may also be distributed over a networked computer system so that computer readable code can be stored and executed in a distributed manner.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art.

Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

Claims (8)

The profile of the microwave communication system is stored and the link distance d, the bandwidth B, the center frequency f and the usage ratio P _u and the intensity RL of the received signal, (ASNR) based on the AI model, and comparing the calculated ASNR-based available signal-to-noise ratio (ASNR) with the calculated signal-to-noise ratio (SNR) An adaptive modulation control unit for setting a priority transmission amount (C _p ) satisfying the following equation (M) and an adaptive transmission scheme;
A plurality of packet grouping units for grouping a plurality of data packets received through a plurality of ports to generate a data packet group;
A switch for transmitting the plurality of data packets, which are applied through a port selected according to control of the modulation control unit, among the plurality of ports to the plurality of packet grouping units;
A plurality of modulation and demodulation units selectively activated in accordance with the control of the modulation control unit and modulated and transmitted according to the adaptive transmission scheme set by the adaptive modulation control unit, And
A dynamic mapping unit for generating and transmitting the distributed data packet group by distributing the data packet group from the plurality of packet grouping units in response to the activated modulation and demodulation unit; Wherein the ATD-AI model-based adaptive modulation transmission control apparatus includes: 2. The apparatus of claim 1, wherein the adaptive modulation control unit
A profile storage section storing the profile including the required availability, the center frequency f, the climate and the terrain factor C, the transmission power TP, the gain G and the loss L elements;
A demand fade margin calculation unit for calculating the demand fade margin (M) from the link distance (d) and the required usability;
A link budget calculator for analyzing the profile to calculate the received signal strength (RL);
The ATD-AI model-based available signal-to-noise ratio (ASNR) is calculated from the bandwidth B, the received signal strength RL, the ratio P _u , the link distance d and the center frequency f. An ASNR calculation unit for calculating an ASNR;
(ASNR) based on the calculated ATD-AI model based on a plurality of adaptive transmission schemes applicable to each of the plurality of adaptive transmission schemes to calculate a priority transmission amount satisfying the required fade margin (M) (C _p ) and a priority transmission amount setting unit for selecting the adaptive transmission scheme;
A traffic attribute analyzer for analyzing an attribute of the data packet applied through the plurality of ports to determine the bandwidth (B); And
A channel number setting unit for determining the number of channels according to the bandwidth (B); Wherein the ATD-AI model-based adaptive modulation transmission control apparatus comprises: 3. The apparatus of claim 2, wherein the ASNR calculation unit
The ATD-AI model-based available signal-to-noise ratio (ASNR)

(Where RL is the received signal strength in dBm, P _u is the ratio used and _p is the slope on the radio link path, ε _p = (receive antenna height - transmit antenna height) / d f is the center frequency (GHz) of the transmitted signal, d is the link distance (Km), and K is Boltzmann's constant of 1.37 * 10 ^-23 J / K. Difference value.)
Wherein the ATD-AI model-based adaptive modulation transmission control apparatus comprises: 4. The apparatus of claim 3, wherein the ASNR calculation unit
The difference value (? B) from the -3 dB bandwidth to the bandwidth (B)

Wherein the ATD-AI model-based adaptive modulation transmission control apparatus comprises: 3. The apparatus of claim 2, wherein the priority transmission amount setting unit
Wherein the maximum difference transmission scheme is selected as a fixed transmission scheme when the available signal-to-noise ratio (ASNR) based on the ATD-AI model is equal to or greater than a signal-to-noise ratio in a maximum- ATD-AI model based adaptive modulation transmission control device. 6. The apparatus of claim 5, wherein the priority transmission amount setting unit
(ASNR) based on the ATD-AI model is greater than or equal to a signal-to-noise ratio (SNR) of each of the plurality of adaptive transmission schemes, and the available signal-to- Wherein the adaptive transmission scheme is set to the adaptive transmission scheme from the lowest order transmission scheme to the highest-order transmission scheme among the adaptive transmission schemes having a signal-to-noise ratio (SNR). 3. The apparatus of claim 2, wherein the link budget calculation unit
(RL) by using a transmission power (TP), a gain (G), and a loss (L) with reference to the profile,

Wherein the ATD-AI model-based adaptive modulation transmission control apparatus comprises: 2. The apparatus of claim 1, wherein the switch
And selects a priority port always receiving a priority data packet corresponding to a priority transmission amount among the plurality of ports under the control of the adaptive modulation control unit.

Images