KR100582902B1 - Power allocation device and power allocation method of mobile communication system - Google Patents

Abstract

The present invention relates to a power allocation device and a power allocation method of a mobile communication system. According to the present invention, first, each user is selected to satisfy the QoS required for each traffic with minimum power as a criterion for selecting a plurality of users that can be transmitted at a specific time. It then reassigns power by comparing the total power allocated to the selected users with the total power allowed.

According to the present invention as described above it is possible to improve the overall system performance through power optimization in two stages.

Packet Scheduling, QoS, Minimum Power Allocation, AMC Options

Description

Power allocating apparatus and power allocating method in mobile communication system {A POWER ALLOCATION APPARATUS AND A POWER ALLOCATION METHOD IN A MOBILE COMMUNICATION}

1 is a view showing a power allocation device according to an embodiment of the present invention.

2 is a diagram illustrating an example of a two-dimensional transmission structure in which power allocation is performed for each user according to a time axis.

3 is a diagram illustrating the packet scheduler shown in FIG. 1 in detail.

4 is a flowchart illustrating a power allocation algorithm according to an embodiment of the present invention.

5 is a diagram illustrating an example of allocation of minimum power according to an embodiment of the present invention.

6 is a diagram illustrating an example of power reallocation according to an embodiment of the present invention.

The present invention relates to a power allocation apparatus and a power allocation method of a mobile communication system, and more particularly, to a power allocation apparatus and a power allocation method associated with packet scheduling in an orthogonal frequency divisional multiple access (OFDMA) system.

In order to efficiently use limited resources in a wireless communication environment, researches on packet scheduling algorithms for evenly distributing radio resources to a large number of users have been actively conducted. That is, as multimedia services requiring various Quality of Service (QoS) are realized, various methods for fairly allocating bandwidth of an output link of a packet scheduler that can efficiently use limited radio resources are proposed. have.

The packet scheduler algorithm of the mobile communication system is left to the implementation. In this case, the performance of the entire system depends heavily on the performance of the algorithm. In particular, there is a need for an efficient algorithm that increases performance efficiency by minimizing power allocation while satisfying QoS using limited resources in a mobile communication environment.

In general, an OFDMA system allocates one user to subcarriers, and the method of allocating the user is divided into two types. Here, a bundle of subcarriers is called a subchannel.

(1) A method of mapping users in the order of subchannels created by the order of subcarriers having good characteristics

(2) A method of allocating a user in each subchannel unit after creating several subchannels by arbitrarily selecting subcarriers.

Like the second method, in the packet scheduler that allocates users in sub-channel units every scheduling time, various methods for maximizing system performance and reducing total transmission power while satisfying QoS such as the minimum guaranteed data rate are provided. Tried.

However, these methods have a problem in that they are complicated to implement or are not related to the commonly used Adaptive Modulation and Coding (AMC) option. Therefore, there is a need for a practical algorithm that is easy to implement and yet fully utilizes the AMC optional features.

The technical problem to be achieved by the present invention is to solve the problems of the prior art, a power allocation device utilizing the AMC option to maximize the overall performance while allocating the minimum power to satisfy the QoS required for each traffic and It is to provide a power allocation method.

The power allocation method of the mobile communication system according to an aspect of the present invention for achieving the above object is

(a) selecting a user from among the total users for packet scheduling;

(b) comparing the total allowable power and the allowable total power for the users selected in step (a); And

(c) reassigning power allocated to the users according to the comparison result in step (c).

On the other hand, the power allocation device of a mobile communication system according to an aspect of the present invention

A packet separator for dividing IP packets input from an upper layer for each user;

A storage unit having a plurality of queues for users identified by the packet separator; And

After scheduling the user to be serviced among the plurality of users, and compares the total allocated power allocated to the selected users and the allowable total power, and includes a packet scheduler for reallocating power according to the comparison result.

Here, the packet scheduler

A user selector which selects users to be serviced from among a plurality of users by performing packet scheduling based on various information including channel information stored in the user queue and QoS; An AMC option selector configured to select an AMC option satisfying a minimum target PER for the user selected by the user selector; A power calculator configured to calculate power to be allocated based on each user's AMC option selected by the AMC option selector; And a power comparison unit for comparing the total power to be allocated and the allowable total power calculated by the power calculator.

Meanwhile, the recording medium according to an aspect of the present invention is a recording medium in which a program for allocating power of a mobile communication system is recorded.

The program

Selecting a user for packet scheduling among the total users;

Comparing total allocated power and allowable total power for the selected users; And

And reassigning power allocated to the users by adjusting each user's AMC option according to the comparison result.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention. Like parts are designated by like reference numerals throughout the specification.

1 illustrates a power allocation apparatus associated with packet scheduling according to an embodiment of the present invention.

As shown in FIG. 1, a power allocation apparatus 100 according to an embodiment of the present invention is included in a base station (not shown), and the base station is connected to at least one user terminal 200a to 200i. Through data transmission and reception, information on a channel state (buffer state, etc.) is provided to a power allocation device.

The power allocation device 100 schedules (prioritizes) traffic data to be transmitted to at least one or more user terminals 200a to 200i, and then allocates power by adjusting an AMC option for selected users.

As described above, in the embodiment of the present invention, the power allocation apparatus 100 is included in the base station to perform scheduling and power allocation for traffic data. However, the present invention is not limited thereto, and the packet is included in various mobile communication systems. The same applies to scheduling and power allocation.

As shown in FIG. 1, an apparatus 100 for allocating power according to an exemplary embodiment of the present invention includes a packet separator 120, a storage 130, and a packet scheduler 140.

The packet separator 120 classifies IP packets input from an upper layer by user and by session of each user. According to an embodiment of the present invention, traffic having a service having the same QoS is defined as a session. That is, the packet separator 120 performs session classification according to QoS for each user and user for the input IP packets, and then stores data for each user and data for each session in the storage 130.

The storage unit 130 includes queues 130a, 130b, ... 130n for each user, and each queue stores sessions according to user QoS (QoS1, QoS2, ..., QoSm). .

The packet scheduler 140 schedules queues with different priorities and then allocates the final power by adjusting the AMC option taking into account the total power allocated to the selected users and the previously serviced data rate. .

FIG. 2 illustrates a two-dimensional transmission structure in which the packet scheduler 140 according to the embodiment of the present invention, allocates and transmits power to users who are finally selected at each scheduling time.

Referring to FIG. 2, several users (user k, user j........ User i) transmitted at a specific scheduling time are allocated different powers. Therefore, it is necessary to allocate power to maximize system performance effects depending on the allocated power.

3 is a diagram illustrating in detail a packet scheduler 140 according to an embodiment of the present invention, and FIG. 4 is a flowchart of a power allocation algorithm performed by the packet scheduler 140 according to an embodiment of the present invention. Hereinafter, a packet scheduling and power allocation algorithm according to an embodiment of the present invention will be described in detail with reference to FIGS. 3 and 4.

As shown in FIG. 3, the packet scheduler 140 according to an embodiment of the present invention may include a user selector 141, an AMC option selector 142, a power calculator 143, and a power comparator 144. Include.

The user selector 141 performs packet scheduling based on various information including channel information stored in the user queues 130a, 130b, ... 130m and QoS for each user and session by using a packet scheduling algorithm. , Select users. In this case, although the minimum guaranteed data rate required for each user is used as an example of QoS according to an embodiment of the present invention, the present invention is not necessarily limited thereto. In addition, as a packet algorithm according to an embodiment of the present invention, various scheduling algorithms including a propagationally fair (PF) algorithm and the like may be used, but are not necessarily limited thereto.

The AMC option selector 142 then selects an AMC option that satisfies the minimum target PER (packet error rate) for the user selected by the user selector 141. In this case, according to an embodiment of the present invention, the AMC option of each user is determined based on a signal-to-interference ratio (SIR) received from each user, but is not necessarily limited thereto. The power calculator 143 calculates a total power to be allocated based on the AMC option for each user selected by the AMC option selector 142.

After performing the above procedure, the power comparator 144 compares the allowable total power with the allocated total power calculated by the power calculator 143. (S30)

As a result of the comparison in step S30, if the total power calculated by the power calculation unit 142 is larger than the allowable total power, the power is repeatedly reduced from the user having a large amount of previously serviced data. If the total power calculated by the power calculation unit 142 is smaller than the allowable total power, the power is increased from the user with a small amount of previously serviced data. (S50) And this process is repeated until the total power allocated to the total allowable power is similar. (S60) By performing the above process, the fairness (fairness) between users is maximized. This process is then repeated while the call continues.

At this time, according to an embodiment of the present invention, the increase or decrease of the power allocated to the corresponding user is performed by adjusting (ie, raising or lowering the AMC option level) the AMC option assigned to each user, as described below. Is achieved.

5 is a diagram illustrating an example of an AMC option that may be used in an OFDMA system. Referring to FIG. 5, when the value of the received SIR is between 4.0 and 7.0 dB, an AMC option stage 2 is selected, and a QPSK modulation scheme and a half coding rate are used.

6 is a diagram illustrating an example of performing a power reallocation algorithm based on the AMC example of FIG. 5.

According to an exemplary embodiment of the present invention, as an example of power reassignment for users allocated with the minimum power, it is assumed that 6 users are finally selected. Referring to FIG. 6, the AMC option selector 142 determines each user's AMC option based on the received signal-to-interference ratio (SIR) value, and the power calculator 143 based on the user-specific AMC option. Calculate the total power allocated. If the calculated total power is less than the total allowable power, select the AMC option one step higher, starting with the user with the lowest data rate previously served.

For example, in FIG. 6, since the data rate previously provided by the user 2 is the smallest at 2 kbps, the AMC option selector 142 converts the user's 2 AMC option from the existing 4 steps to 5 steps. Carry out the reassignment AMC option. The power calculator 143 recalculates the total power (ie, 50 W) increased by the primary reassignment AMC option.

In this case, referring to FIG. 6, since the total power by the first reassigned AMC option is 50 W and the allowable total power is 70 W, again, 2.5 kbps, which is the second lowest data rate among the previously serviced data rates, is used. Perform a second reassignment AMC option by moving user 13's AMC option up one level (that is, converting from step 4 to step 5). This process repeats the above procedure until the total power by the AMC option adjustment is greater than the allowable total power. Referring to FIG. 6, the power allocation method according to the embodiment of the present invention is summarized as follows.

Step 1: Perform total primary reassignment AMC option since total allocated power (50 W) <total allowable total power (70 W)

Step 2: Perform the second reassignment AMC option, because total allocated power (60 W) <total allowable power (70 W)

Step 3: Total allocated power (71 W)> Total allowable power (70 W), so final selection with the previously allocated secondary reassigned AMC option

In the description with reference to FIG. 6, the case in which the AMC option is increased from a user whose data rate is lowered before when the total allocated power is smaller than the allowable total power has been described. If it is larger than the total available power, the AMC option is lowered from the users with a higher data rate previously served. And, since this description is easily understood by those skilled in the art from the above description through FIG. 6, a detailed description thereof will be omitted.

According to the embodiments of the present invention described above, since the packet scheduler of the OFDMA system satisfies the QoS and performs packet scheduling with minimum power for each user, the user can minimize the total power. In addition, system performance can be increased by reallocating power by adjusting AMC options to maximize fairness for users based on data rates previously serviced to selected users.

As mentioned above, although the Example of this invention was described, this invention is not limited only to the Example mentioned above, A various other change and a deformation | transformation are possible. For example, the power allocation device according to the embodiment of the present invention shown in FIG. 1 may be implemented in hardware and may also be implemented in the form of software. The present invention can also be embodied as computer readable code on a computer readable recording medium.

As described above, according to the present invention, it is possible to maximize system overall performance by adjusting AMC options while allocating minimum power to satisfy QoS required for each traffic.

Claims (11)

In the power allocation method of the mobile communication system, (a) selecting a user from among the total users for packet scheduling; (b) comparing the total allowable power and the allowable total power for the users selected in step (a); And (c) reassigning power allocated to users according to the comparison result in step (b). The method of claim 1, In step (c), reallocating power allocated to users by adjusting each user's AMC option. The method of claim 1, Step (b) is Setting a minimum AMC option that satisfies the minimum target PER for the users selected in step (a); And Calculating a total allocated power allocated to each user based on the AMC option set for each user. The method of claim 3, Step (c) is Comparing the calculated total allocated power and the total allowable power of the users; And Reallocating power allocated to users by adjusting each user's AMC option according to the comparison result. The method according to claim 2 or 4, If the total allocation power is less than the total allowable power as a result of the comparison in step (b), the power allocation method is to reallocate the power by increasing the AMC option in the order of the data rates previously serviced in descending order. The method according to claim 2 or 4, If the total allocation power is greater than the total allowable power as a result of the comparison in step (b), the power allocation method is to reallocate the power by decreasing the AMC option in the order of the previous data rate being greater. A packet separator for dividing IP packets input from an upper layer for each user; A storage unit having a plurality of queues for users identified by the packet separator; And After scheduling a user to be serviced among the plurality of users, the total power allocated to the selected users is compared with the allowable total power, and the power of the mobile communication system including a packet scheduler for reallocating power according to the comparison result. Allocation unit. The method of claim 7, wherein The packet scheduler A user selector which selects users to be serviced from a plurality of users by performing packet scheduling based on various information including channel information stored in the user queue and QoS; An AMC option selector configured to select an AMC option satisfying a minimum target PER for the user selected by the user selector; A power calculator configured to calculate power to be allocated based on each user's AMC option selected by the AMC option selector; And And a power comparator for comparing the total power to be allocated and the allowable total power calculated by the power calculator. The method of claim 8, And the AMC option selector increases the AMC options in a descending order of the data rate previously serviced when the total allocated power is less than the allowable total power as a result of the comparison of the power comparator. The method of claim 8, And the AMC option selector decreases the AMC option in a larger order of the data rate previously serviced when the total allocated power is greater than the allowable total power as a result of the comparison of the power comparator. In the recording medium recording a program for allocating power of a mobile communication system, Selecting a user for packet scheduling among the total users; Comparing total allocated power and allowable total power for the selected users; And And a program for reallocating power allocated to users by adjusting each user's AMC option according to the comparison result.

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