JP5586043B2 - Power allocation method and power allocation apparatus in MIMO-OFDM system - Google Patents

Description

  The present invention relates to a power allocation method and power allocation apparatus in a MIMO-OFDM system, and more particularly to a power allocation method and power allocation apparatus for allocating power to a plurality of channels in a MIMO-OFDM system.

  In MIMO (Multi Input Multi Output), a plurality of antennas are used to transmit and receive data via radio. With MIMO, the amount of communication per unit time can be increased.

  Further, as a wireless communication system, OFDM (Orthogonal Frequency Division Multiplexing access) and TDMA (Time Division Multiple Access) are known. OFDMA and TDMA are communication methods for increasing the spectrum (frequency band) utilization efficiency. In OFDMA, spectrum utilization efficiency is improved by sharing a subchannel among a plurality of user terminals.

  A MIMO-OFDMA / TDMA system in which the above-described MIMO and OFDMA / TDMA are combined is known (for example, see Patent Document 1). In this MIMO-OFDMA / TDMA system, a base station (BS) needs to allocate radio resources to user terminals for both the uplink channel and the downlink channel. Here, the radio resources include power and subcarriers. A subcarrier is one of the components constituting a subchannel. In other words, a collection of a plurality of subcarriers is a subchannel.

  In the MIMO-OFDMA / TDMA system, if radio resources are not allocated with certainty, the spectrum efficiency of the channel is lowered. Therefore, a water filling algorithm is used for power allocation. The water injection algorithm assigns power to multiple channels under a constant total power. By using this water injection algorithm, the capacity (communication channel capacity) of the wireless communication system can be maximized.

  However, the term “capacity” used in the water injection algorithm is only a theoretical parameter, and the capacity cannot be measured or evaluated in a practical radio communication system. Therefore, in the conventional wireless communication system, other parameters cannot be changed according to the capacity evaluation result, and the parameters cannot be changed as the user terminal moves, which is not practical. Specifically, when a conventional water injection algorithm is used, more power than necessary may be allocated, and the excessively allocated power causes a reduction in the throughput of the wireless communication system.

Special table 2008-501284

  Accordingly, the main object of the present invention is to provide a practical solution to the above-described problem.

  Specifically, the present invention has been made paying attention to throughput, which is a parameter that can be evaluated in a MIMO-OFDM system, and provides a power allocation method and a power allocation device that can maximize the throughput. The purpose is to do. Another object of the present invention is to provide an improved or expanded water injection algorithm (power allocation program).

  A first aspect of the present invention relates to a method for allocating power to each of a plurality of channels in a MIMO-OFDM system. In this method, a plurality of channels are sorted in the order of SINR values, and power is allocated to the sorted channels according to a water injection algorithm. Subsequently, for each of the plurality of channels, the first power value of the allocated power is compared with the necessary power amount necessary to maximize the data rate as much as possible. Is larger, the required power is allocated to the channel. As a result, it is possible to avoid excessive power allocation to the channel. On the other hand, power allocation is performed according to the water injection algorithm for channels whose first power value is smaller than the required power amount. The second power value assigned at this time is higher than the first power value because the total amount of power that can be assigned is large. Thereby, it is possible to avoid a shortage or waste of power allocated to the channel.

  As a result, according to this aspect, the performance of the MIMO-OFDM system can be maximized. Moreover, according to this aspect, since the data rate is taken into consideration, the capacity is not taken into consideration. As a result, according to this aspect, the conventional problems in the MIMO-OFDM system can be solved, and the MIMO-OFDM system can be made practical.

  In a preferred aspect of the present invention, when the second power value is larger than the required power amount, the required power amount is assigned to the channel instead of the second power value. On the other hand, for a channel whose second power value is smaller than the required power amount, power allocation is performed according to a water injection algorithm similar to the water injection algorithm. As a result, the performance of the MIMO-OFDM system can be maximized more reliably.

  In a preferred aspect of the present invention, the required power amount is calculated based on MCS (MCS: modulation and coding scheme), which is a combination of a modulation scheme and a coding rate. Here, by considering MCS, it is possible to reliably calculate the required power amount so that the data rate is maximized.

  In a more preferred aspect of the present invention, the required power amount is calculated before assigning the first power value. Thereby, the first electric power value and the required electric energy can be quickly compared.

  Also, in a preferred aspect of the present invention, before assigning the first power value, the required power amount is calculated based on MCS that is a combination of a modulation scheme and a coding rate, and after assigning the first power value. Thus, before the second power value is assigned, the required power amount is updated to a small value. That is, the required power amount is determined according to the available (supportable) MCS. As a result, the highest possible data rate can be ensured.

  Further, in a more preferable aspect of the present invention, by using MCS from a group of a plurality of MCSs ranging from an optimal MCS to an unsuitable MCS from the optimal MCS to the optimal MCS in the order of the next best MCS, The required electric energy is calculated to be a value lower than the water filling constant in the water injection algorithm, and is updated to that value. As a result, the required electric energy can be updated to a value close to the water filling constant and smaller than the water filling constant. That is, the required power amount is determined according to the available (supportable) MCS. As a result, the highest possible data rate can be ensured.

  The second aspect of the present invention relates to a power allocation device for allocating power to each of a plurality of channels in a MIMO-OFDM system. The power allocation device includes a sorting unit, a first power allocation unit, a comparison unit, and a second power allocation unit.

  The means for sorting is means for sorting a plurality of channels in the order of SINR values. The first power allocation unit is a unit that allocates power to a plurality of sorted channels according to a water injection algorithm. The comparison unit is a unit that compares, for each of the plurality of channels, the first power value of the power allocated by the first power allocation unit and the necessary power amount necessary to maximize the data rate. If the first power value is larger than the required power amount as a result of the comparison by the comparing means, the second power allocation unit allocates the required power amount to the channel instead of the first power value, and This is a means for allocating power according to a water injection algorithm similar to the water injection algorithm for a channel whose power value is smaller than the required power amount.

  Also by this second side surface, the same effect as the first side surface can be obtained.

  Another aspect of the present invention relates to a program for executing the first aspect described above by a computer or the power allocation apparatus according to the second aspect, and a recording medium storing the program. Also by these side surfaces, the same effects as the first side surface and the second side surface can be obtained.

  According to the present invention, power is allocated to a plurality of channels in consideration of a data rate in a MIMO-OFDM system. Thereby, the throughput of the MIMO-OFDM system can be maximized. That is, the power use efficiency can be increased.

FIG. 1 is a diagram schematically showing a configuration of a wireless communication system of the present invention. FIG. 2 is a flowchart showing a processing procedure of power allocation processing executed by the base station of the wireless communication system. FIG. 3 is a diagram illustrating an example of the relationship between the channel and the power value corresponding to steps S10 to S12 in FIG. FIG. 4 is a diagram illustrating an example of a relationship between a channel corresponding to steps S20 to S22 of FIG. 2 and a power value (required power amount). FIG. 5A is a diagram showing an example of the relationship between the channel and the power value corresponding to steps S30 to S38 in FIG. 2, and FIG. 5B shows the power not allocated in FIG. 5A. It is a figure which shows a value. FIG. 6 is a diagram illustrating an example of a relationship between a channel and a power value (required power amount) when the second power allocation (water injection algorithm) is performed. FIG. 7 is a diagram illustrating an example of a relationship between a channel and a power value (required power amount) when the third power allocation (water injection algorithm) is performed. FIG. 8 is a diagram illustrating an example of a relationship between a channel and a power value (required power amount) when the fourth power allocation (water injection algorithm) is performed. FIG. 9 is a diagram illustrating an example of a relationship between a channel and a power value (necessary power amount) when the fifth power allocation (water injection algorithm) is performed. FIG. 10A is a diagram showing an example of the relationship between the channel and the power value (required power amount) after the power allocation is completed, and FIG. 10B is assigned in FIG. 10A. It is a figure which shows no power value.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. However, the form described below is an example, and can be appropriately modified within a range obvious to those skilled in the art.

  FIG. 1 is a diagram schematically showing a configuration of a wireless communication system of the present invention.

  A wireless communication system 1 shown in FIG. 1 includes one base station 10 and a plurality of user terminals 20. In this aspect, the wireless communication system 1 is a MIMO-OFDM system that combines MIMO and OFDMA.

  The base station 10 includes a plurality of antennas and functions as a channel allocation device or a radio resource allocation device that allocates a channel to each of a plurality of user terminals 20 (also simply referred to as “users”). Specifically, the base station 10 enables radio communication between the user terminals 20 by assigning radio resources to the user terminals 20 (RRA). Radio resources include power and subchannel subcarriers. Radio resource allocation is performed for both the uplink channel and the downlink channel. In this aspect, eigen model transmission (EMT) is applied to MIMO data transmission, whereby user terminals are assigned to all corresponding eigen channels. In addition, although the base station 10 was mentioned as an example of a radio | wireless resource allocation apparatus, what kind of thing may be used as long as it is a device or a controller which can allocate electric power with respect to the user terminal 20. FIG.

  The user terminal 20 includes a plurality of antennas. The user terminal 20 may be any device capable of wireless communication, and may be, for example, a portable device (mobile terminal) or a stationary device. The user terminal 20 performs wireless communication (data transmission / reception) with another user terminal 20 using the channel assigned by the base station 20.

  Next, power allocation by the base station 10 will be described. Note that description of subcarrier allocation by the base station 10 is omitted.

  FIG. 2 is a flowchart showing a processing procedure of power allocation processing executed by the base station 10 of the wireless communication system 1. In this aspect, one base station 10 allocates power to a plurality of channels in the wireless communication system 1 by the processing of FIG. Such power allocation processing is performed according to a power allocation program (algorithm). In the present invention, the power allocation process is executed a plurality of times.

  First, in step S5, information on SINR of a plurality of available channels is obtained.

  In subsequent step S10, the plurality of channels are rearranged so that the SINR is in descending order.

  In step S12, power allocation (first power allocation) is performed according to the water injection algorithm. The water injection algorithm is a program that preferentially allocates the total amount of available power (total power P1) from a channel with less power. As a result, the channel power values (water filling constant, first power value) are equal. The water filling constant at this time is α1. Note that power is not allocated to a channel having a power value higher than the water filling constant α1.

  Subsequently, in step S20, information regarding the optimum MCS is acquired for the channel to which power allocation has been performed. Here, the optimal MCS is an MCS that maximizes the data rate as much as possible. In step S22, a power value required for the corresponding channel (hereinafter also referred to as a required power value) is determined from the acquired information regarding the optimum MCS. That is, according to the MCS, it is possible to determine the necessary power amount necessary to maximize the data rate as much as possible.

In the subsequent step S30, the difference between the water filling constant α (for example α1) and the necessary power value (water filling constant−necessary power value) is calculated for the channel to which power is allocated. In step S32, the difference value is calculated. It is determined whether to take a negative value (less than 0). That is, when this difference value takes a negative value, it can be said that the first power value (water filling constant α) of the allocated power is less than the required power amount. On the contrary, when this difference value is 0 or more, it can be said that the first power value (water filling constant α) of the allocated power is not less than the required power amount. For this reason, in this aspect, when this difference value takes a negative value (that is, when the first power value of the allocated power is less than the required power amount), it is predicted that the corresponding channel will be short of power. Therefore, the process proceeds to step S36 described later without completing the power allocation of the channel. On the other hand, when the difference value is 0 or more (that is, when the first power value of the allocated power is greater than or equal to the required power amount), the process proceeds to S34 in order to perform control for adjusting the power of the corresponding channel. .

As a result of the determination in step S32, when the difference value is 0 or more ( NO in step S30), in step S34, power reassignment (adjustment ) is performed so that the power value of the corresponding channel becomes the required power value. (Ie, set the power value low) to complete power allocation for that channel. Therefore, in the subsequent processing, channels for which power allocation has been completed are excluded from consideration. Thereafter, in step S36, the remaining total power P ′ that can be allocated is calculated for a channel having a negative difference value (YES in step S30) . The remaining total power P ′ that can be allocated is obtained by subtracting the amount of power allocated to a channel for which power allocation has already been completed from all the total power P1 that can be allocated.

  In step S38, it is determined whether or not the power allocation target channel is the remaining one. For example, it may be determined whether or not the result of subtracting the number of channels excluded from consideration (number of excluded channels) from the number of channels to be allocated power (total number of channels) is 1.

  Subsequently, in step S40, power allocation is performed again according to the water injection algorithm. At this time, the power allocation target channel is a channel for which power allocation has not been completed in step S34. Further, the total amount of power that can be allocated at this time is the total power P 'calculated in step S36.

  Subsequently, in step S42, information on the next best MCS is acquired for the channel to which power allocation has been performed. Thereafter, the process returns to step S22 and the subsequent processing is executed. That is, the power value assigned by the water injection algorithm is adjusted in accordance with the acquired information on MCS.

  On the other hand, if the result of determination in step S38 is that there is only one channel to which power is to be allocated, in step S80, information on the next best MCS (in some cases, the least suitable MCS) is obtained for that channel. Allocate power corresponding to the required amount of power. That is, the required electric energy is updated to a small value by changing the MCS. Specifically, the required power amount is updated by using MCS from the optimum MCS to the optimum MCS in the order of the next best MCS from the plurality of MCS groups from the optimum MCS to the least suitable MCS. It is done. As a result, the required electric energy is calculated to be a value lower than the water filling constant in the water injection algorithm, and updated to that value. As a result, the required electric energy can be updated to a value close to the water filling constant and smaller than the water filling constant. That is, the required power amount is determined according to the available (supportable) MCS. As a result, most of the total power P can be allocated to all channels.

  As a result of the processing in step S80, the remaining power that is not allocated may be allocated to the channel for which power was allocated last, may be allocated to other channels, or may be allocated to any channel. It may not be assigned. Also, in order to avoid complication of the processing procedure, the necessary power amount determined from the MCS after the power allocation is performed according to the water injection algorithm for the last channel as well as the other channels. You may adjust it.

  According to the processing of FIG. 2 described above, power is allocated to each of a plurality of channels in the wireless communication system 1 (MIMO-OFDM system). Then, the plurality of channels are sorted in the order of SINR values (step S10), and the first power allocation is performed on the sorted channels according to the water injection algorithm (step S12). Subsequently, for each of the plurality of channels, the first power value (water filling constant α1) of the allocated power is compared with the necessary power amount necessary to maximize the data rate (step S32). If the first power value is larger than the required power amount, the required power amount is assigned to the channel (step S34). As a result, it is possible to avoid excessive power allocation to the channel. On the other hand, for a channel whose first power value is smaller than the required power amount, power allocation is performed according to a second (or subsequent) water injection algorithm (step S40). The second power value assigned at this time is higher than the first power value (water filling constant α1) because the total power amount that can be assigned is large. Thereby, it is possible to avoid a shortage or waste of power allocated to the channel.

  Therefore, according to the processing of FIG. 2 described above, the performance of the wireless communication system 1 can be maximized. Further, according to the processing of FIG. 2, since the data rate (that is, MCS) is taken into consideration, the capacity is not taken into consideration. As a result, according to this aspect, the conventional problem in the MIMO-OFDM system can be solved and the wireless communication system 1 can be made practical. The major difference between data rate and capacity (channel capacity) is that the former is a measurable parameter, while the latter is a theoretical parameter that cannot be measured.

  Further, according to the process of FIG. 2, when the second power value is larger than the required power amount, the updated required power amount is assigned to the channel instead of the second power value (step S42). , S22). On the other hand, for a channel whose second power value is smaller than the required power amount, power allocation is performed according to a water injection algorithm similar to the water injection algorithm. Thereby, the performance of the wireless communication system 1 can be maximized more reliably.

  Further, according to the processing of FIG. 2, in step S22, the required power amount is calculated based on MCS that is a combination of a modulation scheme and a coding rate. Here, by considering MCS, it is possible to reliably calculate the required power amount so that the data rate is maximized.

Further, according to the process of FIG. 2, the necessary power amount is calculated after the first power value is assigned (step S22). Thereby, the first electric power value (water filling constant α1) and the required electric energy can be quickly compared.

In addition, according to the process of FIG. 2, after assigning the first power value, the required power amount is calculated based on the MCS that is a combination of the modulation scheme and the coding rate, and the first power value is assigned. The required power amount is updated to a small value after the time before the second power value is assigned. That is, the required power amount is determined according to the available (supportable) MCS. As a result, the highest possible data rate can be ensured.

  Further, according to the processing of FIG. 2, the required power amount is updated from the plurality of MCS groups from the optimal MCS to the least suitable MCS, from the optimal MCS to the optimal MCS in the order of the next best MCS. This is done by using MCS. In this way, the required power amount is determined according to available (supportable) MCS. As a result, the highest possible data rate can be ensured.

  2 is executed by the base station 10 as described above. That is, the base station 10 functions as a power allocation device for allocating power to each of a plurality of channels. In the wireless communication system 1, a device or device that functions as a power allocation device is not limited to the base station 10 and may be a user terminal 20. Further, an apparatus capable of executing a program corresponding to the process of FIG. 2 and an apparatus including a storage medium storing the program can also achieve the same effect.

  The process shown in FIG. 2 uses an existing water injection algorithm or resource allocation program, and this water injection algorithm is executed a plurality of times (with water filling constants over multiple stages). That is, it can be said that the process of FIG. 2 is an extension or improvement of the existing water injection algorithm.

  In the above-described aspect, when a plurality of channels are below the water filling constant, the power allocation of these channels can be completed. Alternatively, power allocation may be completed one by one by determining whether the SINR value is smaller than the water filling constant in order from the smallest channel. Thereby, the algorithm (program) corresponding to the process of FIG. 2 can be simplified.

  Next, examples of the present invention will be described.

  In this embodiment, the following cases are considered as scenarios.

  First, in a MIMO-OFDM system composed of a plurality of wireless transmitters and wireless receivers, there are six data subchannels that can be used. That is, the number of channels targeted by the multistage water injection algorithm according to the present invention is six.

Furthermore, the following points (1) to (3) were considered as preconditions for the above system.
(1) The signal-to-interference noise ratio (SINR) signal of each subchannel is known in both the wireless transmitter and the wireless receiver.
(2) The multi-stage water injection algorithm according to the present invention is used in a wireless transmitter.
(3) The mapping table shown in Table 1 below can be used in the wireless transmitter. In this mapping table, MCS1 is the optimum MCS and maximizes the data rate, and MCS2 is the suboptimal MCS of the optimum MCS (that is, the second most suitable MCS). As the value of the MCS index increases, the data rate decreases, and the MCS with the largest index (that is, MCSn) is the least suitable MCS, the data rate is the lowest, and the robustness is the strongest.

  Then, the processing (simulation) as shown in FIG. 1 was performed in the system as described above.

  In step S10, as shown in FIG. 3, the six channels are sorted so that the SINR is in descending order. As a result, the channels were sorted in the order of channels CH3, CH4, CH1, CH6, CH5, and CH2. In the subsequent step S12, as shown in FIG. 3, power was poured into the sorted channels according to the water injection algorithm (that is, power allocation was performed). In the example shown in FIG. 3, no power is assigned to the channels CH5 and CH2 having a power value higher than the water filling constant.

  In steps S20 to S22, the required power amount determined according to the optimum MCS is obtained for the channels CH3, CH4, and CH1. The required power amount of each channel CH3, CH4, and CH1 is as shown in FIG. As shown in FIG. 4, when the required power amount exceeds the water filling constant α1 in the channel CH1, it is not necessary to obtain the required power amount for the subsequent channels CH6, CH5 and Ch2. May be).

  In steps S30 to S38, the power allocated to the channels CH3 and CH4 in excess of the required power amount was removed (in other words, the excessive power allocation was stopped). Then, the channels for which power allocation has been completed (channels CH3 and CH4 in FIG. 5A) are excluded from power allocation targets. FIG. 5B shows the remaining power (total power P ′ that can be allocated).

  In steps S40 to S42, power is allocated to a channel for which power allocation has not been completed (second power allocation process). Specifically, the amount of power allocation was determined by recalculating the water filling constant from the remaining power (total power P ′).

  FIG. 6 shows the results when the second power allocation (water injection algorithm) is performed for channels CH1, CH6, CH5, and CH2. In the second power allocation, the water filling constant (α2) was higher than in the first power allocation. Therefore, the required power amount determined according to the optimum MCS can be satisfied for the channel CH1, and the required power amount cannot be satisfied for the channels CH6, CH5, and CH2.

  Therefore, as shown in FIG. 7, the power of the channel CH1 is set to the necessary power amount determined according to the optimum MCS, the excessive power is removed (the allocation of the excessive power is stopped), and the channel CH1 Power allocation has been completed (that is, channel CH1 has been excluded from power allocation targets). On the other hand, for channel CH6, since the required power amount determined according to the optimal MCS exceeds the water filling constant α2, the required power amount determined according to the suboptimal MCS (in this case, the second optimal MCS) is set. Obtained (update of required power).

  Subsequently, as shown in FIG. 7, the third power allocation (water injection algorithm) was performed for the channels CH6, CH5, and CH2. The water filling constant at this time was α3. The required power value after updating channel CH6 (the required power amount determined according to the second optimum MCS) is smaller than the water filling constant α3, specifically, the water filling constant α1 as shown in FIG. It was between ˜α3.

  Therefore, as shown in FIG. 8, the power of the channel CH6 is set to the necessary power amount determined according to the second optimum MCS, the excessive power is removed (allocation is stopped), and the power of the channel CH6 is removed. Completed assignment.

  Subsequently, as shown in FIG. 8, the fourth power allocation (water injection algorithm) was performed for the channels CH5 and CH2. The water filling constant at this time was α4. As shown in FIG. 8, the power value required for the channel CH5 (required power amount determined according to the second optimum MCS) is smaller than the water filling constant α4, specifically, the water filling constants α1 to α4. It was between.

  Therefore, as shown in FIG. 9, the power of the channel CH5 is set to the necessary power amount determined according to the second optimum MCS, the excessive power is removed (allocation is stopped), and the power of the channel CH5 is removed. Completed assignment. On the other hand, for channel CH2, the required power amount determined according to the second best MCS (in this case, the third most suitable MCS) was obtained.

  Subsequently, as shown in FIG. 9, the fifth power allocation (water injection algorithm) was performed for the channel CH2. The water filling constant at this time was α5. The power value required for the channel CH2 (the required power amount determined according to the second optimum MCS) has a water filling constant exceeding α5 and could not be supported. Finally, the power value that can support the water filling constant α5 (the power value smaller than α5) for the channel CH2 is the required power amount determined according to the least suitable MCS.

  Therefore, as shown in FIG. 10 (a), the power of the channel CH2 is set to the necessary power amount determined according to the least suitable MCS, the excessive power is removed (allocation is stopped), and the channel CH5 Completed power allocation for. After all power allocation was completed, the power that was not allocated was small as shown in FIG.

  The present invention can be suitably used in the field of wireless communication (for example, WPAN (Wireless Personal Area Network) defined in IEEE 802.15), in particular, MIMO / OFDMA. Further, the present invention can be suitably used for a next-generation mobile communication system (for example, WPAN (Wireless Metropolitan Area Network) defined in IEEE 802.16).

1 wireless communication system 10 base station
20 User terminal

Claims (3)

A power allocation method for allocating power to each of a plurality of channels in a MIMO-OFDM system,
Sorting the plurality of channels in order of SINR values;
A first power allocation step of allocating power to the sorted plurality of channels according to a water injection algorithm;
Based on MCS, which is a combination of a modulation scheme and a coding rate, a required power amount calculating step for calculating a required power amount necessary to maximize the data rate that can be set on the system as much as possible;
For each of the plurality of channels, a comparison step of comparing the first power value of the power allocated by said first power allocating step, and said required power amount,
As a result of the comparison step, when the first power value is larger than the required power amount, the required power amount is allocated to the channel instead of the first power value, and the first power value is assigned. A second power allocation step of allocating power according to the same algorithm as the water injection algorithm for a channel whose power is smaller than the required power amount;
Including
This maximizes the performance of the MIMO-OFDM system,
Power allocation method. When the second power value of the power allocated in the second power allocation step is larger than the required power amount, the required power amount is allocated to the channel instead of the second power value, and Allocating power to a channel having a second power value smaller than the required power amount according to the same water injection algorithm as the water injection algorithm;
Further including
The power allocation method according to claim 1. A power allocation apparatus for allocating power to each of a plurality of channels in a MIMO-OFDM system,
Means for sorting the plurality of channels in the order of SINR values;
First power allocating means for allocating power to the sorted plurality of channels according to a water injection algorithm;
Based on MCS, which is a combination of a modulation scheme and a coding rate, a required power amount calculating step for calculating a required power amount necessary to maximize the data rate that can be set on the system as much as possible;
For each of the plurality of channels, and comparing means for comparing a first power value of the power to be allocated is the first power allocation means and the required power amount,
As a result of the comparison by the comparison means, if the first power value is larger than the required power amount, the required power amount is assigned to the channel instead of the first power value, and the first power value is assigned. Second power allocating means for allocating power to a channel having a power value smaller than the required power amount according to the same water injection algorithm as the water injection algorithm;
Including
This maximizes the performance of the MIMO-OFDM system,
Power allocation device.

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