KR100592596B1 - Transmission Scheme Allocation Method in Adaptive Transmission Systems - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a transmission method selection method in an adaptive transmission system.

2. The technical problem to be solved by the invention

The present invention provides an adaptive communication system that switches to an appropriate transmission method according to a channel state among a plurality of transmission methods, while satisfying a specific bit error rate required by a communication service according to a reception signal-to-noise ratio while avoiding unnecessary frequent switching. It is intended to provide a transmission method selection method for appropriately selecting a transmission method having efficiency.

3. Summary of the Solution of the Invention

According to the present invention, in a transmission method selection method applied to an adaptive transmission system, a slope is calculated from a signal-to-noise ratio with respect to the past and the present of a received signal, and a cumulative parameter calculation is performed to calculate a cumulative parameter for adjusting a cumulative weight according to the slope. step; A transmission efficiency calculating step of calculating each transmission efficiency according to a current received signal-to-noise ratio for each transmission scheme; A cumulative transmission efficiency calculating step of calculating cumulative transmission efficiency for each transmission scheme by using the respective transmission efficiency and the cumulative parameter; And a transmission method selection step of selecting a transmission method having the maximum transmission efficiency among the cumulative transmission efficiencies, determining whether the selected transmission method is a stable transmission method, and determining switching to the selected transmission method according to the result. Included.

4. Important uses of the invention

The present invention is used in a communication system and the like using an adaptive transmission scheme.

Adaptive transmission system, transmission method selection, received signal-to-noise ratio, data rate, cumulative parameters

Description

Transmission Scheme Allocation Method in Adaptive Transmission Systems             

1 is an exemplary configuration diagram of an adaptive transmission system having multiple transmission and reception schemes to which the present invention is applied.

FIG. 2 is an explanatory diagram showing frequent switching of a transmission scheme caused when the magnitude of a received signal changes rapidly in the vicinity of a threshold for which switching of the transmission scheme is required in an adaptive transmission system to which the present invention is applied; FIG.

3 is a flowchart illustrating an embodiment of a method of selecting a transmission method according to the present invention.

4 is a diagram illustrating an example of a correlation between a slope of a received signal and a cumulative parameter for selecting a transmission scheme according to the present invention.

5A and 5B are detailed flowcharts of one embodiment of a transmission method selection method according to the present invention;

6 is a detailed flowchart illustrating a transmission method selection method including a step of calculating a recursive cumulative transmission efficiency according to the present invention.

7 is a detailed flowchart illustrating a method of selecting a transmission method including a process of calculating a transmission efficiency using a minimum threshold for each retransmission method according to the present invention.

8 is a detailed view illustrating a transmission method selection method including calculating a transmission efficiency using a minimum threshold for each retransmission method and calculating a recursive cumulative transmission efficiency in the adaptive transmission system according to the present invention. Flowchart.

9 is an exemplary diagram illustrating a change in a received signal-to-noise ratio used in an experiment for showing operating characteristics of a selection scheme presented in a transmission method selection method according to the present invention.

FIG. 10 is an exemplary diagram illustrating a change in a received signal-to-noise ratio that vibrates rapidly within a specific range used in an experiment for showing an operating characteristic of the selection scheme presented in the transmission method selection method according to the present invention. FIG.

FIG. 11 is an exemplary diagram illustrating switching of a transmission scheme selected by a technique proposed for a change in the received signal-to-noise ratio of FIG. 9 according to sample time. FIG.

FIG. 12 is an exemplary diagram illustrating a transmission mode switching rate with respect to the change in the received signal-to-noise ratio of FIG. 10. FIG.

The present invention provides a method of selecting a transmission method that can select an appropriate transmission method according to a received signal-to-noise ratio (or a received signal size, that is, a signal-to-noise ratio can be replaced by the size of a received signal) in a communication system using an adaptive transmission scheme. It is about.

Techniques for selecting an appropriate one from several service methods according to the size of a received signal have been similarly handled in a method of selecting an appropriate one among handoff and various diversity antennas in a cellular mobile communication system.

That is, in the cellular mobile communication system, when the communication service is determined to be switched to the proximity base station according to the size of the signal transmitted from the proximity base station and received by the mobile station, or the antenna is switched to an antenna having a large reception signal and excellent reception quality among several reception antennas. In the case of determining, when the magnitude of the received signal from the corresponding base station or antenna is greater than a predetermined threshold, the switching is determined.

At this time, a frequent change occurs between two or more base stations or antennas due to a slight change in the magnitude of the received signal near the threshold value, and a specific value is added to the threshold value to avoid such frequent changeover and to have a hysteresis of the switch. In addition, or by setting a timer to suppress the transition to take hold of the transition decision for a period of time after the transition.

However, the conventional switching determination method as described above is difficult to avoid frequent switching when a signal having a fluctuation range out of the hysteresis range for the threshold is received, and for the hysteresis phenomenon when the difference between each threshold value for the selection target is small. There is a problem that the interval between added thresholds may become narrower or larger than an adjacent threshold.

The present invention has been proposed to solve the above problems, and in an adaptive communication system for switching to an appropriate transmission method according to a channel state among a plurality of transmission methods, a communication service according to a received signal-to-noise ratio while avoiding unnecessary frequent switching It is an object of the present invention to provide a transmission method selection method for appropriately selecting a transmission method that satisfies a specific bit error rate required by the MS and has a maximum transmission efficiency.

In order to achieve the above object, the present invention provides a method for selecting a transmission method applied to an adaptive transmission system, comprising: calculating a slope from a signal-to-noise ratio with respect to the past and present of a received signal, and adjusting a cumulative weight according to the slope; A cumulative parameter calculating step of calculating; A transmission efficiency calculating step of calculating each transmission efficiency according to a current received signal-to-noise ratio for each transmission scheme; A cumulative transmission efficiency calculating step of calculating cumulative transmission efficiency for each transmission scheme by using the respective transmission efficiency and the cumulative parameter; And a transmission method selection step of selecting a transmission method having the maximum transmission efficiency among the cumulative transmission efficiencies, determining whether the selected transmission method is a stable transmission method, and determining switching to the selected transmission method according to the result. Include.

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That is, the present invention intends to select an appropriate transmission scheme according to a received signal-to-noise ratio in an adaptive transmission system in which an appropriate transmission scheme is selected and used according to a channel state among a plurality of transmission schemes.
Each transmission scheme has a different bit error rate and transmission efficiency for the received signal-to-noise ratio, and satisfies a specific bit error rate required by the service in the switching decision, and has a selection preference for a transmission method having a high transmission efficiency.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is an exemplary configuration diagram of an adaptive transmission system having a plurality of transmission and reception schemes to which the present invention is applied, and FIG. 2 is near a threshold where switching of transmission schemes is required in an adaptive transmission system to which the present invention is applied. Is an explanatory diagram showing the frequent switching of the transmission method caused when the magnitude of the received signal changes rapidly.

The signal received over the radio channel changes in signal magnitude and phase due to fading and rainfall, thereby degrading the received signal-to-noise ratio.

The adaptive transmission system detects a change in received signal quality due to a change in channel state and selects an appropriate transmission method that can satisfy a specific service quality required by a communication service among N transmission methods, thereby selecting a transmitter and a receiver. To provide communication services.

In this case, a technique for proper selection is required, and the present invention proposes a determination technique for selecting an appropriate transmission scheme according to the magnitude of a received signal-to-noise ratio.

If the channel condition is good and the received signal-to-noise ratio is relatively large, the higher transmission efficiency is selected to provide a communication service. On the other hand, if the signal-to-noise ratio decreases due to a change in channel state, the transmission efficiency is Select a lower transmission scheme that can provide satisfactory quality of service with a small but reduced signal-to-noise ratio.

Here, the higher transmission method has a higher preference than the lower transmission method because it can provide a communication service with a faster data rate. However, if the reduction of the signal-to-noise ratio does not satisfy the specific required bit error rate (BER) required by the service with a high transmission efficiency, the switch immediately switches to the lower transmission method, although the transmission efficiency decreases. The quality of service below the required bit error rate shall be provided.

On the other hand, when the signal-to-noise ratio increases, the switch immediately switches to a higher scheme that can satisfy the required bit error rate, thereby increasing the transmission efficiency of the communication service.

However, as shown in FIG. 2, when the signal-to-noise ratio changes rapidly near the threshold at which switching of the transmission scheme is required, the adaptive transmission system undergoes frequent switching of the transmission scheme, and thus frequently between the transmitter and the receiver. Delays in the processing required during the exchange and switching of control messages result in a reduction in the amount of transmission for the actual user data.

Therefore, the present invention accumulates the transmission efficiency calculated by the received signal-to-noise ratio of the present as well as the past in order to avoid frequent switching more than necessary, and selects a transmission method having the maximum transmission efficiency at the present time.

In addition, when there is a need to switch from a lower transmission method to a higher transmission method, when the same transmission method continuously has a maximum transmission efficiency for a specific time or more in order to suspend switching until the magnitude of the received signal-to-noise ratio becomes stable, By performing the conversion, it has a hysteretic effect on time and transmission efficiency.

3 is a flowchart illustrating a method of selecting a transmission method according to the present invention, and FIG. 4 is a diagram illustrating an example of a correlation between a slope of a received signal and a cumulative parameter for selecting a transmission method according to the present invention.

The first process and the second process of the transmission method selection method determine the cumulative parameters that can control how much the transmission efficiency calculated by the past received signal-to-noise ratio is reflected in the current selection process (301, 302). In the case of a large signal change, the cumulative parameter is made smaller to give more weight to the present transmission efficiency than in the past, and in the opposite case, the cumulative parameter is increased to reflect the transmission efficiency calculated in the past.

R(t)를 하기의 [수학식 1]과 같이 얻는다. To do this, first, the slope of the past and present received signal-to-noise ratio

R (t) is obtained as shown in Equation 1 below.

를 하기의 [수학식 2]와 같이 계산한다. In Equation 1, R (t) denotes a received signal-to-noise ratio measured at the present time, and R (t-1) denotes a signal-to-noise ratio of the previous past. In addition, t means a sampling time and is an integer represented by 0 or a positive integer. Accumulated parameter at this time using the calculated instantaneous slope

Is calculated as shown in Equation 2 below.

는 덜 민감해지며, 0.5 이상 또는 1에 가까운 값을 갖게 됨으로써 과거의 전송 효율에 많은 비중을 갖게 할 수 있으며, x의 값을 증가시키게 되면 기울기에 대해

는 민감해지고, x의 값을 1 부근의 값으로 선택할 경우,

는 기울기 1을 전후로 하여 가장 민감하다. In Equation 2, x is a positive real constant, and as shown in FIG. 4, the value of the cumulative parameter for the slope may be adjusted according to the value. If you choose a value smaller than 0.5 for the constant x,

Is less sensitive and can have a greater weight on past transmission efficiencies by having values greater than 0.5 or close to 1, and increasing the value of x

Becomes sensitive, and if you choose a value of x around 1,

Is most sensitive with slope 1 before and after.

In addition, when the value of x is greater than or equal to 1, it is again less sensitive to the change in the slope, but as compared with the case where the value of x is smaller than 1, the specific gravity for past transmission efficiency decreases.

On the other hand, the third process is a process of calculating the transmission efficiency for each of the N transmission schemes according to the current received signal size (or received signal to noise ratio) (303).

 Here, the transmission efficiency S (t) is defined as the rate of information bits successfully received without error as shown in Equation 3 below.

In Equation 3, P _b (R, D) is a bit error rate of the transmission scheme D and has different values according to the current received signal-to-noise ratio R and the type D of the transmission scheme, and R _b (D) is the transmission scheme D. Bit rate for the case of providing a communication service.

For relative comparison for each transmission scheme, the present invention uses transmission efficiency normalized by the bit rate R _b (D) of each transmission scheme.

In addition, the bit error rate for a transmission method having an error rate greater than a specific bit error rate P _b ^* required by the communication service is assumed to have a constant P close to 1 (for example, a value of 1), and thus for a transmission method that does not satisfy the service quality. Reduce the transmission efficiency to a very small value That is, the transmission efficiency for each transmission scheme is calculated as shown in Equation 4 below.

The fourth process is a process of calculating the cumulative transmission efficiency for each transmission method using the cumulative parameter calculated by Equation 2 above (304).

는 하기의 [수학식 5]와 같이 과거 일정 기간 L동안의 전송 효율에 대해 누적 파라미터

의 지수 승의 가중치를 갖는 합으로 계산된다. Cumulative Transmission Efficiency

Is a cumulative parameter for the transmission efficiency for a certain period L in the past, as shown in Equation 5 below.

Is calculated as the sum with the weight of the exponent.

In a fifth process, for each transmission scheme, a transmission scheme in which the cumulative transmission efficiency calculated by Equation 5 is maximized is selected (305).

In the sixth process, when the selected transmission scheme is lower than the transmission scheme selected in the past, commands are transmitted to the transmitter and the receiver to switch to the selected transmission scheme (306 and 309).

On the other hand, if the method is higher than the past transmission method, it is checked whether the same transmission method is selected for a specific time to determine whether the current selection is a stable selection (306, 307).

If the result of the check is 307, if the same selection has been made continuously for a period of time or longer, the switchover is instructed to the currently selected transmission scheme (309); Avoid. At this time, just before the currently selected transmission scheme is selected, the current transmission scheme is converted to the past transmission scheme (308) and then converted back to the currently selected transmission scheme (309), thereby maintaining the past transmission scheme.

5A and 5B are detailed flowcharts illustrating an embodiment of a method of selecting a transmission method in an adaptive transmission system according to the present invention, which illustrates the procedure of FIG. 3 in more detail.

The transmission method selection method according to the present invention has a register and a table as shown in Table 1 below. Initially, the register and the table contents are initialized to predetermined values (501 and 502). In Table 1 below, T_max, BER_table, BER_req, and P are initialized to predetermined values at design time of the adaptive communication system, and do not change during the operation process.

After the initialization process, the slope is calculated by Equation 1 from the received signal-to-noise ratios of the current and past time points (503) (see the description of process "301"), and the cumulative parameter is obtained by Equation 2 above. 504,505 (see process description 302 above).

The following process calculates the cumulative transmission efficiency for each transmission scheme (see process description of "303" and "304" above).

First, the variable i to distinguish the transmission scheme is initialized to 1 (506). By obtaining a bit error rate BER from BER_table according to the current received signal-to-noise ratio (507), and if BER is greater than the required bit error rate BER_req, replace BER by a constant P close to 1 (508,509) to have a high bit error rate, The transmission efficiency is calculated to be close to zero (510). On the other hand, if the BER is less than or equal to the requested bit error rate BER_req, the process proceeds directly to "510".

After that, the calculated transmission efficiency is recorded in S_table for the cumulative transmission efficiency (511), and the cumulative transmission is performed as the sum of the exponential power of the cumulative parameter with respect to the transmission efficiency for the past L period by Equation (5). The efficiency is calculated and recorded in S_acc (512). Cumulative transmission efficiency is achieved for all N transmission schemes (513,514).

Next, the transmission method having the maximum cumulative transmission efficiency is selected using the cumulative transmission efficiency obtained through the above process, and the same transmission is continuously performed during the T_max period when the selected transmission method is higher than the previous transmission method. The method determines whether an optimal transmission scheme is selected by checking whether a scheme has been selected (see the above description of steps “305” to “309”).

First, the transmission scheme D having the maximum transmission efficiency is selected from the S_acc table (528), and it is checked whether the previous transmission scheme is higher than the past transmission scheme (515).

As a result of the check, in the case of the lower method, the timer T_hold value is set to T_max to switch to the lower method in the next process (516).

As a result of the check, it is checked whether the currently selected transmission scheme is the same as the past continuous selective transmission scheme D_cont in the case of the higher scheme (517).

As a result, in the same manner, the value of T_hold is increased by 1 (518).
As a result of the check, if it is not the same method, the currently selected transmission method is replaced with the continuous selection transmission method D_cont (519), and the timer T_hold is initialized to 0 (520).

Next, it is checked whether the T_hold value is greater than or equal to T_max (521).

If the current transmission scheme is lower or higher than the past scheme but is continuously selected for the T_max time in the above process, T_hold has a value of T_max or more, and commands the switching of the transmission scheme.

In this case, D_cont is replaced with the transmission scheme D to be switched currently (523), and T_hold is initialized to 0 (524).

On the other hand, when T_hold is smaller than T_max, the switching of the transmission scheme is not required. Therefore, the transmission scheme currently selected to maintain the past transmission scheme is replaced with the past transmission scheme D_prev (522).

Finally, if a transmission scheme different from the past transmission scheme is selected (525), the transmitter and receiver are instructed to switch the transmission scheme (526), and the current transmission scheme is recorded in the past transmission scheme D_prev (527).

After performing such a series of processes, the process returns to the slope calculation process 503 to repeatedly determine the transmission mode at the next time 500. To this end, the slope is calculated in a state in which T is increased by one.

At this time, in order to obtain the cumulative transmission efficiency for the past L period, S_table ( NL size table) that records L transmission efficiencies for each transmission scheme is required. In order to reduce the storage space, Equation 5, which is a cumulative transmission efficiency calculation method, may be replaced by Equation 6 below.

은 바로 전 과거 시간에 계산된 누적 전송 효율이다. 상기 [수학식 6]을 사용할 경우, 바로 전 과거의 누적 전송 효율만을 필요로 하기 때문에 S_table은 필요로 하지 않고 누적 전송 효율은 S_acc(N1크기)에 기록하여 사용한다.In Equation 6,

Is the cumulative transmission efficiency calculated just in the past. In case of using Equation 6, since only the cumulative transmission efficiency of the previous past is required, S_table is not required and the cumulative transmission efficiency is recorded and used in S_acc (N1 size).

In the case of using Equation 6, the operation of FIG. 5A is modified as in FIG.

FIG. 6 is a detailed flowchart illustrating a method of selecting a transmission method including a step of calculating a recursive cumulative transmission efficiency according to an exemplary embodiment of the present invention. 304 "process description).

That is, after the step 303 of calculating the current transmission efficiency, the current transmission efficiency is sequentially decreased by C , 2 C , ...., mC , ... for the lower transmission scheme that satisfies the required bit error rate. 601 to 603 are added, where C is a constant having a value between 0 and 1.

In the case of using only Equation 6, since the lower transmission method cannot recover from the higher transmission method, an extremely small constant of 1 or less is artificially accumulated from the transmission efficiency for the transmission method that satisfies the required bit error rate. It enables recovery to the transmission method. Therefore, the smaller the value of the constant C is, the more constrained the transition to the higher way.

At this time, the determination method in the operation of FIG. 5 requires a table that records the bit error rate for the received signal-to-noise ratio for each transmission method, and calculates the bit error rate and the transmission efficiency therefrom.

On the other hand, without calculating the transmission efficiency from the direct bit error rate, the minimum received signal-to-noise ratio, which cannot satisfy the required bit error rate for each transmission scheme, is determined in advance, and the current received signal-to-noise ratio is compared with the minimum threshold for each transmission scheme. Thus, when the current received signal-to-noise ratio is greater than or equal to the minimum threshold for each transmission scheme, it may be calculated to have a transmission efficiency of 1 and a transmission efficiency of 1-P if less.

This method does not require a table for the bit error rate, and can reduce the required storage space by requiring only a minimum threshold value for each transmission scheme as shown in Table 2 below. FIG. 7 and FIG. 8 are flowcharts illustrating a case where current transmission efficiency is determined by comparing thresholds. FIG. 7 is accumulated by Equation 5, and FIG. 8 is accumulated by Equation 6. It is for the case of calculating the transmission efficiency.

FIG. 7 is a detailed flowchart illustrating a method of selecting a transmission method including a process of calculating transmission efficiency using a minimum threshold value for each retransmission method according to the present invention. Parts 507 to 510 for calculating transmission efficiency (see process description of "303" above).

That is, a comparison between the threshold values selects a transmission method corresponding to an area in which the current signal-to-noise ratio is larger than the threshold value of the corresponding transmission method and smaller than the threshold value of the immediately higher transmission method (701 to 711).

Compared with the transmission scheme selected in this process, the higher transmission scheme has a transmission efficiency of 1-P, and the lower transmission scheme has a transmission efficiency of one. The transmission efficiency for each transmission scheme determined as described above is used to calculate the cumulative transmission efficiency together with the transmission efficiency recorded in the past.

8 is a detailed view illustrating a transmission method selection method including calculating a transmission efficiency using a minimum threshold for each retransmission method and calculating a recursive cumulative transmission efficiency in the adaptive transmission system according to the present invention. As a flowchart, the method of FIGS. 6 and 7 is applied to FIG. 5.

That is, the portions 602 to 604 (see the "304" process description) for which the cumulative transmission efficiency is calculated by Equation 6 are the same as those in FIG. 6, and the current transmission efficiency is determined by comparing the thresholds. Portions 701 to 710 (see process description "303" above) are the same as in FIG. 7, and the remaining portions are the same as in FIG. 5.

Next, in order to show the operation characteristics of the transmission scheme selection method of the present invention, an experimental result of an adaptive transmission system having eight transmission schemes is shown as an example.

The 8th transmission method has the largest data rate for the lower subordinate transmission methods, the data rate decreases in the order of 7, 6, ..., and the received signal-to-noise ratio required to satisfy a specific bit error rate. Has a lower number of lower levels than the higher level.

FIG. 9 is an exemplary view illustrating a change in a received signal-to-noise ratio used in an experiment for showing operating characteristics of a selection scheme presented in a transmission scheme selection method according to the present invention, and FIG. 10 is a diagram illustrating a transmission scheme selection method according to the present invention. This is an example showing the change of the received signal-to-noise ratio which vibrates rapidly within the specific range used in the experiment to show the operating characteristics of the selection technique.

9 and 10 show the change in the received signal-to-noise ratio used in the experiment with time, and FIG. 9 illustrates the characteristics of the selection technique for the case where the magnitude of the signal-to-noise ratio continuously decreases and then inverts and rises. 10 is an example for showing a characteristic of a case of rapidly changing around a specific value.

FIG. 11 is an exemplary view illustrating switching of a transmission scheme selected by the technique proposed for the change in the reception signal-to-noise ratio of FIG. 9 according to a sample time, and FIG. 12 is a transmission scheme switching rate of the change in the reception signal-to-noise ratio of FIG. It is an example showing the.

That is, FIG. 11 illustrates the transmission scheme selected by the technique described with reference to FIGS. 5A and 5B over time with respect to the change in the received signal-to-noise ratio of FIG. 9. Here, 0.1 is used as the value of parameter x in [Equation 2], and sample lengths for three received signal-to-noise ratios are used as window lengths.

In the falling portion of the signal-to-noise ratio, an immediate switching is performed in a transmission scheme that has the largest cumulative transmission efficiency, and in the rising portion, there is a delay to suspend switching to a higher transmission scheme according to the maximum duration value. When the maximum duration is 3 samples or more, the switching from the lowest transmission scheme 1 to the highest transmission scheme 8 is performed without switching to the intermediate transmission scheme. Therefore, if the signal-to-noise ratio continues to increase, it is shown that the selection of the maximum duration avoids unnecessary switching to the intermediate transmission scheme.

In addition, FIG. 12 illustrates the transmission method switching ratio with respect to the window length when the technique described in FIGS. 5A and 5B is used for the change in the received signal-to-noise ratio of FIG. 10. Here, 0.1 was used as the value of the parameter x as in the above example.

As the length of the window increases, the conversion rate decreases. Similarly, as the maximum duration increases, the conversion rate decreases by suppression of switching to a higher transmission scheme. If the maximum duration is 0, it may be considered that the hold process for switching the higher transmission mode is not applied, and a significant decrease in conversion rate can be seen by using the hold process by the maximum duration. In addition, an increase in window length from 1 to 3 shows a marked decrease in conversion rate.

When used in a practical adaptive transmission system, only unconditional reduction of the conversion rate should not be preferred, and the window length and maximum duration should be appropriately selected in consideration of the transmission efficiency that is reduced on average by suppression of switching to higher transmission schemes. . In addition, the value of the parameter x which adjusts the transmission efficiency accumulation ratio according to the change rate of the signal-to-noise ratio should also be appropriately selected.

In order to effectively explain the present invention, as an example, an adaptive communication system providing a communication service by appropriately applying a plurality of transmission schemes according to the size of a received signal-to-noise ratio due to a change in the characteristics of a radio channel is targeted.

However, the selection method of the present invention can be applied to other communication systems having a plurality of selection targets, and other channel state information other than the received signal-to-noise ratio is used as the information for selection, or the required quality of service is transmitted to other service request information other than the bit error rate. Can be used.

The method of the present invention as described above may be implemented as a program and stored in a computer-readable recording medium (CD-ROM, RAM, ROM, floppy disk, hard disk, magneto-optical disk, etc.).
The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes are possible in the art without departing from the technical spirit of the present invention. It will be clear to those of ordinary knowledge.

As described above, the present invention provides a transmission scheme that satisfies a specific quality required by a communication service and has a maximum transmission efficiency in an adaptive communication system that switches to an appropriate transmission scheme according to a channel state among a plurality of transmission schemes. There is an excellent effect that can be properly selected according to the noise ratio.

In addition, the present invention has a history action that can avoid the switching of the frequent transmission method in the selection process, and in particular, when switching from the lower transmission method to the higher transmission method is required, the frequent switching by holding the switch until the switching request is continued There is an excellent effect that can reduce the transmission efficiency and the degradation of the quality of service.

Claims (6)

In the transmission method selection method applied to the adaptive transmission system, A cumulative parameter calculating step of calculating a slope from a signal-to-noise ratio with respect to past and present of the received signal and calculating a cumulative parameter for adjusting a cumulative weight according to the slope; A transmission efficiency calculating step of calculating each transmission efficiency according to a current received signal-to-noise ratio for each transmission scheme; A cumulative transmission efficiency calculating step of calculating cumulative transmission efficiency for each transmission scheme by using the respective transmission efficiency and the cumulative parameter; And A transmission method selection step of selecting a transmission method having the maximum transmission efficiency among the cumulative transmission efficiencies, determining whether the selected transmission method is a stable transmission method, and determining switching to the selected transmission method according to the result; Transmission method selection method in the adaptive transmission system comprising a. The method of claim 1, The transmission efficiency calculation step, A transmission method selection method in an adaptive transmission system, characterized in that the transmission efficiency is calculated using a minimum threshold for each retransmission method. The method according to claim 1 or 2, The cumulative transmission efficiency calculating step, A transmission method selection method in an adaptive transmission system, characterized in that the cumulative transmission efficiency is calculated by a recursive cumulative transmission efficiency calculation method. The method of claim 3 The cumulative parameter calculating step, Obtaining a slope from a difference between a past received signal to noise ratio and a current received signal to noise ratio, and recording the current ratio as a past ratio; And Calculating a cumulative parameter in inverse relation to the slope from the slope Transmission method selection method in the adaptive transmission system comprising a. The method of claim 3 The transmission method selection step, Selecting a transmission scheme having a maximum transmission efficiency among the calculated cumulative transmission efficiencies; A determination step of determining whether the selected transmission scheme is higher than a past transmission scheme; Switching to the selected method if it is not an upper method as a result of the determination of the determining step; And As a result of the determination in the determining step, switching to the selected method when the same selection is made for a continuous time if it is a higher method Transmission method selection method in the adaptive transmission system comprising a. delete

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