KR20120027925A - Apparatus and method for scheduling based on velocity of terminal in broadband wireless access system - Google Patents

Abstract

PURPOSE: A scheduling method considering of the moving speed of a terminal in a broadband wireless connection system and method thereof are provided to reduce the static calculation rate of a signal-to-noise ratio in a broad band wireless connecting system by measuring the change rate of channels. CONSTITUTION: A terminal receives an establishment information for measuring a channel change rate from a base station(1001). The terminal measures the channel change rate according to the establishment information(1005). The terminal determines the change of a resource permutation method according to the change rate(1011). The terminal requests the change of the resource permutation method to the base station(1013).

Description

A scheduling apparatus and method considering the moving speed of a terminal in a broadband wireless access system {APPARATUS AND METHOD FOR SCHEDULING BASED ON VELOCITY OF TERMINAL IN BROADBAND WIRELESS ACCESS SYSTEM}

The present invention relates to a broadband wireless access system, and more particularly, to an apparatus and method for efficiently scheduling a base station according to a speed of a terminal in a broadband wireless access system.

Currently, the mobile communication system is evolving in the form of providing various services such as broadcasting, multimedia video, and multimedia messages mainly in voice communication. As a next-generation communication system, a commercially available Institute of Electrical and Electronics Engineers (IEEE) 802.16e system and 3GPP Long Term Evolution (LTE), IEEE 802.20 Ultra Mobile Broadband (UMB), and IEEE 802.16m system are currently being standardized. Etc.

The services to be provided in the next generation communication system require high data rates. As one of the techniques for satisfying the high data rate, MIMO (Multiple Input Multiple Output) technology using a plurality of transmit and receive antennas is drawing attention. The MIMO technology is a technology that can significantly improve the channel capacity than when using a single antenna by performing communication using a plurality of streams through a plurality of antennas. For example, if both transmitters and receivers use M transmit and receive antennas, the channels between each antenna are independent, and the bandwidth and total transmit power are fixed, the average channel capacity can be increased by up to M times compared to a single antenna. do.

For example, the IEEE 802.16m system considers the application of the MIMO technology. In the IEEE 802.16m system, when the MIMO mode using the MIMO technology is applied, a subband logical resource unit (SLRU) that binds physically adjacent subcarriers of a resource used and a sub-carrier that is distributed to a miNibnad Logical Resource (NLRU) Unit and DLRU (Distributed Logical Resource Unit). In general, since the SLRU is a bundle of physically adjacent resources, it is advantageous for resource allocation of a mobile station that is not moving or is moving slowly, whereas the NLRU and the DLRU are bundles of physically distributed resources, so that the channel change moves at a high speed. It is advantageous for resource allocation of a mobile station. Accordingly, the base station should provide an efficient scheduling method in consideration of the movement speed and the characteristics of the resource to the base station to properly allocate the resource allocation scheme to each terminal to increase the overall system capacity and performance.

Accordingly, an object of the present invention is to provide an apparatus and method for efficient scheduling in consideration of the movement speed and resource characteristics of a terminal in a broadband wireless access system.

Another object of the present invention is to provide an apparatus and method for determining a low speed mode and a high speed mode of a terminal in a broadband wireless access system.

Another object of the present invention is to provide an apparatus and method for selecting a distributed resource region and a local resource region according to a moving speed of a terminal in a broadband wireless access system.

According to a first aspect of the present invention for achieving the above object, a method of operating a terminal in a broadband wireless access system, the process of receiving the configuration information for measuring the channel change amount from the base station, and measuring the channel change amount in accordance with the configuration information And determining whether to convert the resource permutation scheme according to the channel change amount, and requesting to convert the resource permutation scheme.

According to a second aspect of the present invention for achieving the above object, a method of operating a base station in a broadband wireless access system, the process of transmitting the configuration information for measuring the channel change amount from the base station, and the conversion of the resource permutation scheme from the terminal And receiving a request and performing a scheduling according to the requested resource permutation scheme.

According to a third aspect of the present invention for achieving the above object, in a broadband wireless access system, a terminal device receives a setting information for measuring channel change amount from a base station, and measures the channel change amount according to the setting information, And determining whether to convert the resource permutation scheme according to the channel change amount, and controlling the request to convert the resource permutation scheme.

According to a fourth aspect of the present invention for achieving the above object, in a broadband wireless access system, a base station apparatus receives a request for conversion of a resource permutation method from a modem and a terminal for transmitting configuration information for measuring channel variation from a base station; The controller may include a controller that performs scheduling according to the requested resource permutation scheme.

The complexity of the implementation of the terminal is reduced by greatly reducing the statistical calculation of the signal-to-noise ratio used for the speed estimation of the terminal in the broadband wireless access system. Accordingly, the implementation burden of the terminal can be reduced, and the calculation speed and the determination speed can also be improved. In addition, there is an advantage that can increase the existing system capacity and performance even while reducing the complexity of the terminal.

1 is a diagram illustrating an example of a frame structure of a broadband wireless access system according to an embodiment of the present invention;
2 is a diagram illustrating an example of resource region permutation of a broadband wireless access system according to an embodiment of the present invention;
3 is a view illustrating operation of a feedback channel in a broadband wireless access system according to an embodiment of the present invention;
4 is a diagram illustrating local frequency domain resource allocation and distributed frequency domain resource allocation according to channel characteristics in a broadband wireless access system according to an embodiment of the present invention;
5 is a diagram illustrating a simulation result of speed estimation using channel quality of a subband in a broadband wireless access system according to an embodiment of the present invention;
6 is a diagram illustrating an error probability of estimating a moving speed of a terminal using channel quality of all subbands in a broadband wireless access system according to an embodiment of the present invention;
7 is a diagram illustrating an error probability of estimating a moving speed of a terminal using channel quality of one subband in a broadband wireless access system according to an embodiment of the present invention;
8 is a diagram illustrating a procedure for changing a permutation method of resources in a broadband wireless access system according to an embodiment of the present invention;
9 is a diagram illustrating an operation procedure of a base station in a broadband wireless access system according to an embodiment of the present invention;
10 is a diagram illustrating an operation procedure of a terminal in a broadband wireless access system according to an embodiment of the present invention;
11 is a block diagram of a base station in a broadband wireless access system according to an embodiment of the present invention;
12 is a block diagram of a terminal in a broadband wireless access system according to an exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

Hereinafter, the present invention will be described an efficient scheduling technique in consideration of the characteristics of the movement speed and resources of the terminal in a broadband wireless access system. Hereinafter, the present invention will be described using an orthogonal frequency division multiplexing (OFDM) / orthogonal frequency division multiple access (OFDMA) wireless communication system as an example.

1 illustrates an example of a frame structure of a broadband wireless access system according to an exemplary embodiment of the present invention.

Referring to FIG. 1, a frame includes a super frame 110 of a unit. The super frame 110 is composed of four frames 120. The frame 120 is composed of eight subframes 134. The subframe 134 is composed of five to seven symbols 140. A super frame header 132 is transmitted through the start subframe of the super frame 110. System information necessary for accessing the system is transmitted through the super frame header 132. For example, the length of the super frame 110 may be 20 ms, and the length of the frame 120 may be 5 ms.

2 illustrates an example of resource region permutation of a broadband wireless access system according to an exemplary embodiment of the present invention.

Referring to FIG. 2, in the frequency domain, resources are composed of physical resource units (PRUs). The PRU consists of 18 subcarriers and 6 symbols. Subbands are formed by grouping four adjacent PRUs. According to the embodiment shown in FIG. 2, the permutation begins with initial subband partitioning. By the subband division, some of the subbands of the entire subbands are also used in a state including a physically adjacent frequency domain, and the remaining subbands are permutated in units of PRU. As a result, subbands composed of adjacent subcarriers and PRUs subjected to permutation are distinguished.

Subbands composed of the adjacent subcarriers are allocated and used without further permutation, and a Resource Unit (RU) belonging to the subband is referred to as a Subband Logical Resource Unit (SLRU) or a local resource. In addition, some PRUs in the subbands passing through the miniband permutation 220 of the PRU unit are used in a state in which 18 adjacent subcarriers are bundled without further permutation. An RU composed of 18 adjacent subcarriers passing through the miniband permutation 220 is called a NLRU (miNibnad Logical Resource Unit) or distributed resource. Finally, the remaining PRUs in the subbands that go through the miniband permutation 220 of the PRU unit go through the subcarrier permutation 230. Here, the subcarrier permutation 230 is performed in units of two adjacent subcarriers. An RU that has passed through both the miniband permutation 220 and the subcarrier permutation 230 is called a DLRU (Distributed Logical Resource Unit) or distributed resource.

In a broadband wireless access system according to an embodiment of the present invention, a feedback channel is used to receive feedback of downlink channel information of a terminal. The report period of the feedback channel is determined into two types, a short-term period and a long-term period according to a MIMO feedback mode and a feedback format. . The MFM depends on the MIMO mode and the permutation type. In addition, according to the MFM, the content of the feedback information transmitted from the terminal to the base station is different. For example, the content of permutation type, MIMO mode, and feedback information for each MFM may be defined as shown in Table 1 below.

MFM Perm type MIMO mode Feedback information 0 DLRU, NLRU MIMO mode 0, 1 (OL SU SFBC / SM switching)
STC rate 1 = SFBC
STC rate> 1 = SM
Max Mt: DLRU = 2, NLRU = 4 STC rate
Wideband CQI One N / A N / A N / A 2 SLRU MIMO mode 1 (OL SU SM)
1 <= STC rate <= 4 STC rate
Subband CQI
Subband selection 3 SLRU MIMO mode 2 (CL SU SM)
1 <= STC rate <= 4 STC rate
Subband CQI
Subband PMI
Subband selection
Wideband corr. Matrix 4 NLRU MIMO mode 2 (CL SU SM)
1 <= STC rate <= 4 Wideband CQI
Wideband PMI
Wideband corr.
Matrix 5 SLRU MIMO mode 3 (OL MU)
1 <= MaxMt <= 4 Subband CQI
Subband selection
MIMO stream
indicator 6 SLRU MIMO mode 4 (CL MU)
1 <= MaxMt <= 4 Subband CQI
Subband PMI
Subband selection
Wideband corr. Matrix 7 NLRU MIMO mode 4 (CL MU)
1 <= MaxMt <= 4 Wideband CQI
Wideband PMI
Wideband corr. Matrix

When the MFM is determined, a feedback format is determined. When the feedback format is determined, the content and the period of the feedback information transmitted from the terminal to the base station are determined. As a specific example, Table 2 below shows a feedback format when the MFM is 0, 4, 7. Referring to Table 2 below, in case of MFM 0, feedback format 0 is determined, and if feedback format 0 is determined, a channel for transmitting feedback information becomes a primary fast-feedback channel (PFBCH) and transmits the same. Periods include both short and long periods, which include the full-band wideband channel quality indicator (CQI) and space time coding rate (STC) or event driven indocator (EDI). Full-band CQI and STC rates are transmitted.

MFM Feedback
format FBCH Num of
reports Report
period Feedback fields Note 0 0 PFBCH 2 short Wideband CQI and
STC rate
Or EDI Encoding type 0 (Joint encoding of CQI and STC rate) long Wideband CQI and
STC rate Encoding type 0 (Joint encoding of CQI and STC rate)
Long-term FPI for FFR No long-term report when q = 0 4 0 PFBCH 2 short Wideband CQI and
STC rate
Or EDI Encoding type 0 (Joint encoding of CQI and STC rate) long Wideband PMI PMI Encoding type 2 No long-term report when q = 0 One SFBCH 2 short Wideband CQI
Wideband STC rate
Wideband PMI
PFBCH indicator 7 0 PFBCH 2 short Wideband CQI
Or EDI STC rate = 1
Encoding type 0 long Wideband PMI PMI for rank 1
Encoding type 2
No long-term report
when q = 0 One SFBCH 2 short Wideband CQI
Wideband PMI
PFBCH indicator

3 illustrates operation of a feedback channel in a broadband wireless access system according to an exemplary embodiment of the present invention.

Referring to FIG. 3, the terminal determines positions of feedback channels allocated to the user through feedback channel allocation information 310. Here, the feedback channel allocation information may be referred to as 'Feedback Allocation AMAP IE'. Accordingly, the terminal transmits feedback information through the PFBCHs 321-1 and 321-2 and the Secondary Fast-feedback Channel (SFBCH) 322. In other words, when the MFM is determined, the terminal transmits feedback information through the PFBCH or SFBCH to the base station. The PFBCH is mainly used for transmission of a fullband CQI (Wideband CQI) and a resource request of the UE, a switch request of the MIMO mode, buffer status information of a hybrid-automatic repeat reQuest (HARQ), and the SFBCH is mainly a narrowband CQI Narrowband CQI) and MIMO feedback is used for the transmission of information. In addition, the period of each control channel varies depending on the MFM and the allocation information. In this case, the base station informs the terminal of the corresponding information through the feedback channel allocation information.

4 illustrates local frequency domain resource allocation and distributed frequency domain resource allocation according to channel characteristics in a broadband wireless access system according to an exemplary embodiment of the present invention.

In the OFDMA radio channel environment, there are relatively good and bad areas according to the frequency domain. In this case, a region having a relatively good channel characteristic varies depending on the terminal. In addition, a phenomenon in which the degree of change in channel characteristics varies depending on the speed of the terminal. For example, the wireless channel characteristics of a terminal moving at a high speed change rapidly, and the wireless channel characteristics of a terminal moving at a slow speed change slowly. Therefore, a terminal moving at a high speed generally uses a distributed frequency allocation scheme to ensure a steady performance even if the channel characteristics are changed. A terminal moving at a slow speed changes its channel characteristics slowly so that only a region having good channel characteristics is selectively selected. Selecting and assigning can maximize frequency efficiency, resulting in improved overall system capacity and performance.

In the broadband wireless access system according to an embodiment of the present invention, the terminal may request to change the MIMO mode through the PFBCH. For example, the information requesting the change of the MIMO mode may be configured as shown in Table 3 below.

Index Content (Value) Description / Notes 57 Event-driven Indicator (EDI) for request for switching MFM Indicates request to switch MIMO feedback Mode between distributed and localized allocations

In requesting the change of the MIMO mode, the UE should determine whether and how to change the MIMO mode according to a defined criterion. Parameters representing the determination criteria should be delivered to the terminals. For example, all terminals may use a broadcast message that can be received. In the case of an 802.16m system, an AAI_SCD (Advanced Air Interface_System Configuration Descriptor) message may be used. Here, the parameters representing the determination criteria may be defined as shown in Table 4 below.

M / O Attributes size
(bits) Values / Note Condition M MIMO Mode
Trigger Period 2 The observation window size of the each measured subband CINR to calculate the standard deviation
0b00: 4 frames
0b01: 8 frames
0b10: 16 frames
0b11: 32 frames N.A
M MIMO Mode
Trigger Throshold 6 Threshold of the standard deviation of the each measured subband CINR over the given period to trigger MIMO mode transition between distributed and localized allocations.
Range: 0.00 to 2.00 dB (0.05dB unit) N.A M MIMO Mode
Trigger Number of
selected
subbands 2 The number of subbands of which the AMS shall calculate the standard deviation trigger MIMO mode transition between distributed and localized allocations.
0b00: 1 subband
0b01: 2 subbands
0b10: 6 subbands
0b11: 12 subbands N.A

The UE measures a change in channel quality, for example, a carrier to interference and noise ratio (CINR), observed for a specific time as a criterion for changing the MIMO mode. The most representative indicator used for measuring the change amount is Standard Deviation. In Table 4, the parameter 'Period' means a specific time interval for calculating the standard deviation of the CINR values in each subband. When the standard deviation of the CINR value is higher than a specific threshold, the terminal determines that the channel change amount is high due to the high speed, and accordingly, requests the base station to use a distributed resource. On the other hand, if the standard deviation is lower than the specific threshold, the terminal determines that the channel change amount is small due to the low speed, and accordingly, requests the base station to use localized resources. In Table 2, the parameter 'threshold' means the specific threshold. In addition, when the standard deviation is measured, the calculation for each subband may be a large operation in actual implementation. In other words, the MIMO mode change request of the UE is delayed due to the time delay and the calculation amount generated in calculating the standard deviation of all the subbands, and the complexity of the UE may increase the cost required in actual implementation. have. Accordingly, the present invention proposes a method of measuring the standard deviation using only one subband.

However, when the standard deviation is measured using only one subband, using only a single threshold causes a large difference in performance depending on the value of the threshold. For example, the larger the threshold value, the higher the probability that the high speed mode is incorrectly determined as the low speed mode, while the smaller the threshold value, the higher the probability that the low speed mode is incorrectly determined as the high speed mode. Therefore, when using only one threshold value, determination of the low speed mode and the high speed mode of the terminal may be biased to one side. In other words, when operating with a small threshold value, the possibility of erroneously determining the high speed mode as the low speed mode is reduced, while increasing the probability of erroneously judging the low speed mode as the high speed mode. On the contrary, when operating with a large threshold value, the possibility of erroneously judging the low speed mode as the high speed mode is lowered while the possibility of erroneously judging the high speed mode as the low speed mode increases.

Accordingly, in order to solve the trade-off problem as described above, the present invention proposes a method of supporting a plurality of thresholds. That is, a first threshold value, which is a criterion for switching a high speed mode using distributed resources, to a low speed mode using local resources, and a second reference, which is a reference for switching a low speed mode using local resources to a high speed mode using distributed resources. By separately defining the thresholds, the trade off problem can be solved. For example, the parameters representing the determination criteria in consideration of the plurality of thresholds may be defined as shown in Table 5 below.

M / O Attributes size
(bits) Values / Note Condition M MIMO Mode
Trigger Period 2 The observation window size of the each measured subband CINR to calculate the standard deviation
0b00: 4 frames
0b01: 8 frames
0b10: 16 frames
0b11: 32 frames N.A
M MIMO Mode
Trigger Threshold 1 6 Threshold of the standard deviation of the each measured subband CINR over the given period to trigger MIMO mode transition from distributed to localized allocations.
Range: 0.00 to 2.00 dB (0.05dB unit) N.A
M MIMO Mode
Trigger Threshold 2 6 Threshold of the standard deviation of the
each measured subband CINR over the given period to trigger MIMO mode transition from localized to distributed allocations.
Range: 0.00 to 2.00 dB (0.05dB unit) N.A M MIMO Mode
Trigger Number of
selected
subbands 2 The number of subbands of which the AMS
shall calculate the standard deviation
trigger MIMO mode transition between
distributed and localized allocations.
0b00: 1 subband
0b01: 2 subbands
0b10: 6 subbands
0b11: 12 subbands N.A

FIG. 5 illustrates a simulation result of speed estimation using channel quality of a subband in a broadband wireless access system according to an exemplary embodiment of the present invention.

In the simulation, observations were made for several frames to measure channel variation of the terminals, and the graph of FIG. 5 shows a cumulative distribution function of standard deviations calculated for subband CINRs for each of four frames. function). In the legend, 'Max' means using data only of the maximum value among the standard deviations of all 12 subbands, and 'Random' means the standard deviation of only one subband instead of the whole. It means using only. As shown in the graph of FIG. 5, it can be seen that the high speed terminal and the low speed terminal can be sufficiently distinguished even when only one subband data is used. For the UE, it is clear that continuously calculating the CINR standard deviation of each of the subbands in every instant is a burden, so even without using the standard deviation value of only one subband, there is no significant performance degradation. Being able is a big advantage. That is, the terminal determines that the CINR standard deviation of the specific section measured by the terminal is higher than the threshold using the information received from the base station as a high speed, and determines that it is a low speed if it is lower than the threshold.

FIG. 6 illustrates an error probability of estimating a moving speed of a terminal using channel quality of all subbands in a broadband wireless access system according to an exemplary embodiment of the present invention, and FIG. 7 illustrates movement of a terminal using channel quality of one subband. Error probability of velocity estimation is shown.

6 and 7 illustrate a probability that a determination error occurs when the terminal estimates the high speed or the low speed using a specific threshold. In the case of FIG. 6, the threshold is 1.35, and in the case of FIG. 7, the threshold is 0.6. 6 and 7, the horizontal axis represents the number of consecutive observations, and the vertical axis represents the probability of error occurrence. The number of observations refers to the number of times that the terminal should compare the standard deviation and the threshold to determine the high speed or the low speed. For example, when the number of consecutive observations is 5, the terminal determines that the terminal is high speed only when it is determined that all five times are high speeds. That is, the terminal determines that it is high speed if the standard deviation of the CINR exceeds the threshold in all five consecutive times.

FIG. 6 shows the result of determining with the highest standard deviation value using all standard deviations of all subbands. In FIG. 6, 'Period' of Table 4 is set to 4 frames as 0b00, 'threshold' is set to 1.35, and 'Number of selected subbands' is set to 12 subbands as 0b11. As shown in FIG. 6, when the number of consecutive observations is 1, about 7% of cases of determination errors occur at low speed, and about 24% of cases of determination errors occur at high speed. 7 illustrates a case where only one subband standard deviation is used, and the threshold is set to 0.6. As shown in FIG. 7, the determination error occurs at a low speed of about 6%, and the determination error occurs at a high speed of about 22%. Increasing the number of consecutive observations to five or more reduces the probability of error to about 1% in both cases. That is, FIG. 6 and FIG. 7 demonstrate that it is possible to show sufficient performance even if only one subband statistics are used without utilizing the CINR statistics of the entire subbands. In other words, even if only one subband is used, the complexity and system capacity of the terminal can be improved without deterioration of performance.

8 illustrates a procedure of changing a permutation scheme of resources in a broadband wireless access system according to an embodiment of the present invention. FIG. 8 illustrates an operation of both a base station and a terminal during a process of determining a resource permutation method, that is, a change between a distributed resource and a local resource. The change in presentation method is shown.

Referring to FIG. 8, in step 801, the base station transmits a system configuration descriptor (SCD) message. The SCD message is a broadcasting message including system information. The SCD message includes information about an observation period for calculating CINR standard deviation, a threshold for referencing an MFM transform, and the number of subbands to be observed. Thereafter, in step 803, the terminal acquires information such as the observation period, the threshold value, the number of subbands, etc. by receiving the SCD message. Thereafter, in step 805, the UE measures the CINR of the observed subband through a midamble every frame. Subsequently, in step 807, the UE determines whether the CINR measurement period for the observation subband is the same as the observation period included in the SCD message. If the measurement period is not the same as the observation period, the flow returns to step 805 and the terminal continues the CINR measurement. On the other hand, if the measurement period is the same as the observation period, in step 809, the terminal calculates the standard deviation of the CINRs for the observation subband.

In step 811, the terminal determines whether the MFM conversion condition is satisfied in consideration of the current MFM and the threshold. For example, when using an NLRU, that is, an MFM mode using a distributed area allocation mode, the terminal compares the threshold with the CINR standard deviation, and if the standard deviation is small, the MFM transformation should be requested. To judge. In this case, when there are a plurality of thresholds, a threshold corresponding to the current MFM mode of the terminal is used. If the MFM conversion condition is satisfied, in step 813, the terminal transmits an EDI requesting MFM conversion to the base station, and in step 815, the base station receives the EDI. Accordingly, in step 817, the base station transmits a feedback allocation MAP IE (Feedback Allocation A-MAP IE) according to the converted MFM. Then, in step 819, the base station schedules according to the converted MFM for the terminal. Subsequently, in step 821, the terminal receives the feedback allocation MAP IE, confirms that the MFM conversion request is normally performed, and then performs communication according to the converted MFM. Thereafter, returning to step 805, the UE continuously calculates the CINR standard deviation of the observed subbands every frame and determines whether the MFM conversion condition is satisfied.

An embodiment of the present invention described with reference to FIG. 8 is a specific embodiment of converting a permutation method of a resource by converting an MFM (MIMO feedback mode). However, the permutation scheme transformation of the present invention may be performed through a procedure other than the format of the MFM transformation, for example, directly changing the resource permutation. In this case, since the feedback allocation MAP IE of step 817 indicates a change of the MFM mode, step 817 may be omitted or may be replaced by transmitting a message other than the feedback allocation MAP IE.

9 is a flowchart illustrating an operation procedure of a base station in a broadband wireless access system according to an exemplary embodiment of the present invention.

Referring to FIG. 9, the base station transmits configuration information for measuring channel variation in step 901. The configuration information includes information such as an observation period for calculating a standard deviation of channel quality, at least one threshold value as a reference for determining whether to convert a permutation scheme, and the number of subbands to be observed. The configuration information may be broadcast so that all of the terminals connected to the base station can be received, and may be transmitted periodically. For example, the configuration information may be part of a super frame header or an SCD message. For example, the setting information may be configured as shown in <Table 4> or <Table 5>.

Thereafter, the base station proceeds to step 903 and checks whether the resource permutation scheme conversion is requested from the terminal. In other words, the base station determines whether the local resource is requested from the terminal using the distributed resource, or whether the distributed resource is requested from the terminal using the local resource. In this case, according to a specific embodiment, the conversion request of the permutation method may be made through various procedures. For example, the resource permutation type conversion request may be performed through a format of the MFM conversion request. For example, the conversion of the resource permutation scheme may be requested through an indicator as shown in Table 3 above.

If the conversion of the resource permutation scheme is not requested, the base station proceeds to step 905 to perform scheduling according to the current permutation scheme. That is, the base station allocates a resource in a resource region, for example, a local resource region or a distributed resource region, according to the current permutation scheme of the terminal to the terminal, and performs communication through the allocated resource.

On the other hand, if the conversion of the resource permutation scheme is requested, the base station proceeds to step 907 and transmits a message indicating the transformation of the permutation scheme. For example, when the resource permutation type conversion request is performed through a format of the MFM conversion request according to an embodiment of the present invention, the message indicating the conversion of the permutation type may be a feedback allocation MAP IE. However, when the permutation scheme conversion is performed through another format according to another embodiment of the present invention, step 907 may be omitted or replaced by transmitting a message other than the feedback allocation MAP IE.

In step 909, the base station performs scheduling according to the converted permutation scheme. That is, the base station allocates a resource in a resource region, for example, a local resource region or a distributed resource region, according to the transformed permutation scheme of the terminal to the terminal and performs communication through the allocated resource.

10 illustrates an operation procedure of a terminal in a broadband wireless access system according to an embodiment of the present invention.

Referring to FIG. 10, in step 1001, the terminal receives configuration information for measuring channel variation. The configuration information includes information such as an observation period for calculating a channel change amount, at least one threshold value as a reference for determining whether to convert a permutation scheme, and the number of subbands to be observed. The configuration information may be broadcast so that all of the terminals connected to the base station can be received, and may be transmitted periodically. For example, the configuration information may be part of a super frame header or an SCD message. For example, the setting information may be configured as shown in <Table 4> or <Table 5>.

Thereafter, the terminal proceeds to step 1003 and determines whether a time point of measuring channel quality for the subband arrives. Since the channel quality should be measured according to a predetermined period in order to measure the channel change amount, the terminal determines whether a time point for measuring the channel quality for the subband arrives. For example, the measurement of the channel quality may be performed in units of frames, that is, one frame.

When a time point of measuring channel quality for the subband arrives, the terminal proceeds to step 1005 and measures channel quality for at least one subband indicated by the configuration information. In selecting at least one subband to be subjected to the channel quality measurement, the terminal randomly selects at least one subband. For example, the terminal generates a random number and selects a subband based on the random number. However, during one observation period, it is preferable that at least one selected subband remains the same. In this case, the terminal may measure the channel quality for the subband using at least one of preamble, midamble and general pilot signals.

Subsequently, the terminal proceeds to step 1007 to determine whether an observation time point for calculating a standard deviation of channel quality arrives. The calculation of the standard deviation is performed in accordance with the period indicated by the setting information. Therefore, the terminal determines whether a time point for calculating the channel change amount arrives according to the period indicated by the configuration information. If the observation time does not arrive, the terminal returns to step 1003.

On the other hand, when the observation time arrives, the terminal proceeds to step 1009 to calculate the channel variation, that is, the standard deviation of the channel quality. That is, the terminal calculates the standard deviation of the channel qualities measured during one period of the observation period. The standard deviation reflects the change in channel quality on the time axis. If the channel qualities of the plurality of subbands are measured, the terminal uses the average channel quality of the frame or calculates an average of standard deviations for each subband.

After calculating the standard deviation, the terminal proceeds to step 1011 and determines whether the conversion condition of the resource permutation scheme is satisfied. Whether the conversion condition is satisfied is determined by comparing the standard deviation with the at least one threshold. For example, when one threshold value is used as shown in Table 4, the terminal compares the standard deviation with the one threshold value, and if the standard deviation is larger, the distributed resource is smaller and the standard deviation is smaller. If so, decide to use local resources. That is, the conversion condition is that the standard deviation is less than the threshold if the terminal is currently using distributed resources, and the conversion condition is that the standard deviation is greater than the threshold if the terminal is currently using local resources. do. As another example, when two thresholds, that is, a first threshold for conversion to local resources and a second threshold for conversion to distributed resources are used as shown in Table 5, the terminal is currently distributed resources. The conversion condition is that the standard deviation is less than the first threshold value when the value is in use, and the standard deviation is greater than the second threshold value when the terminal is currently using local resources. If the conversion condition is not satisfied, the terminal returns to step 1003.

On the other hand, if the conversion condition is satisfied, the terminal proceeds to step 1013 and requests the permutation scheme conversion to the base station. In this case, the terminal may explicitly request the transformation of the permutation scheme, or may request the transformation in another format related to the selection of the permutation scheme. For example, the terminal may request conversion of the permutation method through a conversion request of the MFM. In this case, the terminal may request through the indicator as shown in Table 3. However, according to another embodiment of the present disclosure, the terminal may determine whether to request a conversion based on a plurality of consecutive comparison results instead of one comparison result as in step 1011. In other words, for the accuracy of the determination of the necessity of conversion, the terminal may request the conversion when the conversion condition is satisfied N times in succession for N observation periods.

After requesting the conversion of the permutation scheme, the terminal proceeds to step 1015 and checks whether a message indicating the transformation of the permutation scheme is received from the base station. For example, when the resource permutation type conversion request is performed through a format of the MFM conversion request according to an embodiment of the present invention, the message indicating the conversion of the permutation type may be a feedback allocation MAP IE. However, when the permutation scheme conversion is performed through another format according to another embodiment of the present invention, step 1015 may be omitted or may be replaced by transmitting a message other than the feedback allocation MAP IE.

If a message indicating the conversion of the permutation scheme is received, the terminal proceeds to step 1017 to perform communication according to the converted permutation scheme.

11 is a block diagram of a base station in a broadband wireless access system according to an embodiment of the present invention.

As illustrated in FIG. 11, the base station includes a radio frequency (RF) processor 1110, a modem 1120, a storage unit 1130, and a controller 1140.

The RF processor 1110 performs a function for transmitting and receiving a signal through a wireless channel such as band conversion and amplification of the signal. That is, the RF processor 1110 up-converts the baseband signal provided from the modem 1120 to an RF band signal and transmits the signal through an antenna, and downlinks the RF band signal received through the antenna to a baseband signal. To convert. In FIG. 11, only one antenna is shown, but the base station may include a plurality of antennas.

The modem 1120 performs a baseband signal and bit string conversion function according to the physical layer standard of the system. For example, during data transmission, the modem 1120 generates complex symbols by encoding and modulating a transmission bit stream, maps the complex symbols to subcarriers, and then performs an Inverse Fast Fourier Transform (IFFT) operation and CP ( Cyclic Prefix) is used to configure OFDM symbols. In addition, upon receiving data, the modem 1120 divides the baseband signal provided from the RF processor 1110 in OFDM symbol units and restores signals mapped to subcarriers through a fast fourier transform (FFT) operation. After that, the received bit stream is recovered by demodulation and decoding. In addition, the modem 1120 performs coding and encoding according to MIMO technology, for example, space time coding (STC).

The storage unit 1130 stores data such as a basic program, user traffic, configuration information, and system information for the operation of the base station. The storage unit 1130 provides stored data at the request of the controller 1140.

The controller 1140 controls the overall operations of the base station. For example, the controller 1140 configures downlink data, provides the downlink data to the modem 1120, and interprets uplink data provided from the modem 1120. The controller 1140 includes a scheduler 1142 for performing scheduling, and the scheduler 1142 performs scheduling for the terminal under the control of the controller 1140. In particular, according to an embodiment of the present invention, the controller 1140 controls the function for the resource permutation scheme conversion of the terminal as follows.

First, the controller 1140 transmits setting information for measuring a channel change amount through the modem 1120 and the RF processor 1110. The configuration information includes information such as an observation period for calculating a standard deviation of channel quality, at least one threshold value as a reference for determining whether a permutation scheme is converted, the number of subbands to be observed, and the like. The setting information may be configured as shown in <Table 4> or <Table 5>. Subsequently, when a request for conversion of the resource permutation method is requested from the terminal, the controller 1140 transmits a message indicating the conversion of the permutation method. For example, the resource permutation type conversion request may be performed through a format of the MFM conversion request. For example, the conversion of the resource permutation scheme may be requested through an indicator as shown in Table 3 above. In this case, the message for notifying the permutation scheme may be a feedback allocation MAP IE. However, when the permutation scheme conversion is performed through another format according to another embodiment of the present invention, the function of transmitting the message may be excluded or replaced by a function of transmitting a message other than the feedback allocation MAP IE. have. When the permutation scheme is converted, the controller 1140 performs scheduling according to the converted permutation scheme. That is, the scheduler 1142 allocates a resource in a resource region, for example, a local resource region or a distributed resource region, according to the converted permutation scheme of the terminal to the terminal, and the controller 1140 allocates the allocated resource. Control to perform communication through.

12 is a block diagram of a terminal in a broadband wireless access system according to an exemplary embodiment of the present invention.

As illustrated in FIG. 12, the base station includes an RF processor 1210, a modem 1220, a storage 1230, and a controller 1240.

The RF processor 1210 performs a function for transmitting and receiving a signal through a wireless channel such as band conversion and amplification of the signal. That is, the RF processor 1210 up-converts the baseband signal provided from the modem 1220 to an RF band signal and then transmits the signal through an antenna, and downlinks the RF band signal received through the antenna to a baseband signal. To convert. In FIG. 12, only one antenna is illustrated, but the terminal may include a plurality of antennas.

The modem 1220 performs a baseband signal and bit string conversion function according to the physical layer standard of the system. For example, during data transmission, the modem 1220 generates complex symbols by encoding and modulating a transmission bit stream, maps the complex symbols to subcarriers, and then configures OFDM symbols through IFFT operation and CP insertion. do. In addition, upon receiving data, the modem 1220 divides the baseband signal provided from the RF processor 1210 in OFDM symbol units, restores signals mapped to subcarriers through an FFT operation, and then demodulates and decodes the signal. Restore the received bit string through. In addition, the modem 1220 performs coding and encoding according to MIMO technology, for example, space time coding (STC).

The storage unit 1230 stores data such as a basic program, an application program, and user content for the operation of the terminal. The storage unit 1230 provides stored data at the request of the controller 1240. In particular, the storage unit 1230 stores information about fixed resources for group data of a service group subscribed to the terminal.

The controller 1240 controls the overall operations of the terminal. For example, the controller 1240 configures downlink data, provides the downlink data to the modem 1220, and interprets uplink data provided from the modem 1220. In particular, according to an embodiment of the present disclosure, the controller 1240 includes a channel change calculator 442 and a permutation determiner 444, and controls a function for converting a resource permutation scheme of the terminal as follows. do.

First, the control unit 1240 receives the setting information on the channel variation measurement transmitted from the base station through the RF processing unit 1210 and the modem 1220, and stores the setting information in the storage unit 1230. . The configuration information includes information such as an observation period for calculating a standard deviation of channel quality, at least one threshold value as a reference for determining whether a permutation scheme is converted, the number of subbands to be observed, and the like. The setting information may be configured as shown in <Table 4> or <Table 5>. Subsequently, the channel change calculator 1242 measures channel quality for at least one subband indicated by the configuration information according to a predetermined period, and according to the observation period indicated by the configuration information, the channel change amount, that is, Calculate the standard deviation of the channel quality. Here, the channel quality may be measured in one frame period. When the standard deviation is calculated, the permutation determiner 444 determines whether the resource permutation conversion condition is satisfied using the standard deviation and at least one threshold included in the configuration information. For example, when one threshold is used as shown in Table 4, if the terminal is currently using distributed resources, the conversion condition is that the standard deviation is smaller than the threshold, and the terminal is currently in local resources. Is the conversion condition that the standard deviation is greater than the threshold. As another example, when two thresholds, that is, a first threshold for conversion to local resources and a second threshold for conversion to distributed resources are used as shown in Table 5, the terminal is currently distributed resources. The conversion condition is that the standard deviation is less than the first threshold value when using a value, and the conversion condition is that the standard deviation is greater than the second threshold value when the terminal is currently using local resources. When the conversion condition is satisfied, the controller 1240 requests the base station to convert the permutation scheme. In this case, the terminal may explicitly request the transformation of the permutation scheme, or may request the transformation in another format related to the selection of the permutation scheme. For example, the controller 1240 may convert the MFM. A request for conversion of the permutation scheme may be requested through the request. In this case, the controller 1240 may use an indicator as shown in Table 3 above. However, according to another embodiment of the present disclosure, the permutation determiner 444 may determine whether to request a conversion based on a plurality of consecutive comparison results instead of one comparison result as in step 1011. After requesting the conversion of the permutation scheme, the controller 1240 checks whether a message indicating the transformation of the permutation scheme is received from the base station. For example, when the resource permutation type conversion request is performed through a format of the MFM conversion request according to an embodiment of the present invention, the message indicating the conversion of the permutation type may be a feedback allocation MAP IE. However, when the permutation scheme conversion is performed through another format according to another embodiment of the present invention, the function of receiving a message indicating the transformation of the permutation scheme is excluded or a message other than the feedback allocation MAP IE is excluded. It can be replaced by the function of receiving. Thereafter, the controller 1240 controls to perform communication according to the converted permutation scheme.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by the equivalents of the claims.

Claims (38)

In the method of operating a terminal in a broadband wireless access system,
Receiving configuration information for measuring channel variation from a base station;
Measuring a channel change amount according to the setting information;
Determining whether to convert the resource permutation scheme according to the channel change amount;
Requesting conversion of the resource permutation scheme.
The method of claim 1,
The setting information may include at least one of an observation period for calculating a channel change amount, at least one threshold value as a reference for determining whether a permutation scheme is converted, and the number of subbands to be observed.
The method of claim 2,
Wherein the configuration information is received via one of a super frame header and an SCD message.
The method of claim 2,
The process of measuring the channel change amount,
Measuring channel quality for the number of subbands indicated by the configuration information according to a first period;
And calculating a standard deviation of the channel quality measured during one second period according to the second period.
The method of claim 4, wherein
The first period is one frame,
And the second period is two or more frames.
The method of claim 4, wherein
The process of measuring the channel quality,
Randomly selecting as many subbands as the indicated number;
Measuring channel quality for the selected subband.
The method of claim 2,
Wherein said at least one threshold comprises one threshold for transforming to local resources and to distributed resources.
The method of claim 7, wherein
The process of determining whether to convert the resource permutation method according to the channel change amount,
If the terminal is currently using the distributed resource, determining that the standard deviation is smaller than the threshold, and converting to a resource permutation method corresponding to the local resource;
And when the terminal is currently using the local resource, determining that the standard deviation is greater than the threshold to convert to a resource permutation method corresponding to the distributed resource.
The method of claim 2,
Wherein the at least one threshold comprises a first threshold for conversion to local resources and a second threshold for conversion to distributed resources.
10. The method of claim 9,
The process of determining whether to convert the resource permutation method according to the channel change amount,
If the terminal is currently using the distributed resource, determining that the standard deviation is less than the first threshold value, and converting to a resource permutation method corresponding to the local resource;
And when the terminal is currently using the local resource, determining that the standard deviation is greater than the second threshold to convert to a resource permutation method corresponding to the distributed resource.
The method of claim 1,
The process of requesting the transformation of the resource permutation scheme may include:
And sending an indicator requesting a conversion to one of the MIMO feedback mode with the NLRU or DLRU as the permutation type and the MIMO feedback mode with the SLRU as the permutation type.
The method of claim 11,
And after the request for conversion to the MIMO feedback mode, receiving a MAP IE including feedback resource allocation information for the requested MIMO feedback mode.
In the method of operating a base station in a broadband wireless access system,
Transmitting setting information for measuring channel variation from a base station;
Receiving a request for conversion of a resource permutation scheme from a terminal;
Performing scheduling according to the requested resource permutation scheme.
The method of claim 13,
The setting information may include at least one of an observation period for calculating a channel change amount, at least one threshold value as a reference for determining whether a permutation scheme is converted, and the number of subbands to be observed.
The method of claim 14,
Wherein the configuration information is received via one of a super frame header and an SCD message.
The method of claim 14,
Wherein said at least one threshold comprises one threshold for transforming to local resources and to distributed resources.
The method of claim 14,
Wherein the at least one threshold comprises a first threshold for conversion to local resources and a second threshold for conversion to distributed resources.
The method of claim 13,
The process of requesting the conversion of the resource permutation scheme,
And receiving an indicator requesting a conversion to one of the MIMO feedback mode with the NLRU or DLRU as the permutation type and the MIMO feedback mode with the SLRU as the permutation type.
The method of claim 18,
And after receiving a request for conversion to the MIMO feedback mode, transmitting a MAP IE including feedback resource allocation information for the requested MIMO feedback mode.
A terminal device in a broadband wireless access system,
A modem receiving configuration information for measuring channel variation from a base station;
And a controller for measuring a channel change amount according to the setting information, determining whether to convert the resource permutation scheme according to the channel change amount, and then controlling to request the resource permutation scheme to be converted.
The method of claim 20,
The configuration information may include at least one of an observation period for calculating a channel change amount, at least one threshold value as a reference for determining whether a permutation scheme is converted, and the number of subbands to be observed.
The method of claim 21,
Wherein the configuration information is received via one of a super frame header and an SCD message.
The method of claim 21,
The controller measures channel quality for the number of subbands indicated by the configuration information according to the first period and calculates a standard deviation of the measured channel quality during one second period according to the second period. Characterized in that the device.
The method of claim 23, wherein
The first period is one frame,
And the second period is two or more frames.
The method of claim 23, wherein
The controller may randomly select as many subbands as the indicated number and then measure channel quality of the selected subbands.
The method of claim 21,
And the at least one threshold comprises one threshold for conversion to local resources and conversion to distributed resources.
The method of claim 26,
The controller, when the terminal is currently using the distributed resources, if the standard deviation is less than the threshold value determines that the conversion to the resource permutation method corresponding to the local resources, the terminal currently uses the local resources And if the standard deviation is greater than the threshold, converting to a resource permutation method corresponding to the distributed resource.
The method of claim 21,
And the at least one threshold comprises a first threshold for conversion to local resources and a second threshold for conversion to distributed resources.
The method of claim 28,
The control unit, when the terminal is currently using the distributed resources, if the standard deviation is less than the first threshold value, determines that the resource permutation method corresponding to the local resources, and the terminal is currently the local resources If the standard deviation is greater than the second threshold value is used, characterized in that for determining the resource permutation method corresponding to the distributed resources.
The method of claim 1,
The control unit transmits an indicator requesting conversion to one of the MIMO feedback mode using the NLRU or DLRU as the permutation type and the MIMO feedback mode using the SLRU as the permutation type to request the conversion of the resource permutation method. And control to make it.
The method of claim 30,
And the modem, after requesting the conversion to the MIMO feedback mode, receives the MAP IE including feedback resource allocation information for the requested MIMO feedback mode.
A base station apparatus in a broadband wireless access system,
A modem for transmitting setting information for measuring channel variation from a base station;
And a controller for receiving a request for conversion of the resource permutation scheme from the terminal and performing scheduling according to the requested resource permutation scheme.
33. The method of claim 32,
The configuration information may include at least one of an observation period for calculating a channel change amount, at least one threshold value as a reference for determining whether a permutation scheme is converted, and the number of subbands to be observed.
The method of claim 33, wherein
Wherein the configuration information is received via one of a super frame header and an SCD message.
The method of claim 33, wherein
And the at least one threshold comprises one threshold for conversion to local resources and conversion to distributed resources.
The method of claim 33, wherein
And the at least one threshold comprises a first threshold for conversion to local resources and a second threshold for conversion to distributed resources.
33. The method of claim 32,
The control unit receives an indicator for requesting conversion to one of the MIMO feedback mode using the NLRU or the DLRU as the permutation type and the MIMO feedback mode using the SLRU as the permutation type to receive the request for the resource permutation method. Device characterized in that.
The method of claim 37,
The control unit, after receiving a request for conversion to the MIMO feedback mode, characterized in that for controlling to transmit a MAP IE including feedback resource allocation information for the requested MIMO feedback mode.

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