JP2009284327A - Radio transceiver device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio transceiver device capable of satisfying a minimum guaranteed transmission rate specified respectively for each cell edge group and cell central group, and capable of comprehensively improving transmission rates of an MS in a sector by effectively using a radio resource. <P>SOLUTION: The radio transceiver device includes: a cell edge determination part 109 for grouping the cell under the cell edge group and the cell central group by a cell edge determination threshold value; a minimum transmission rate detection part 111 for detecting the minimum guaranteed transmission rate of the mobile radio communication terminal (MS) in each group; and a cell edge determination threshold value updating part 114 for calculating to update a cell edge determination threshold value with the use of the cell edge determination threshold value calculating formula in answer to the number of MSs of the cell edge group and the cell central group, and the minimum guaranteed transmission rate set to the detected minimum transmission rate and each group as an index. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a radio transmission / reception apparatus in a digital radio communication system, and more particularly to a radio transmission / reception apparatus that improves the transmission rate of mobile radio terminals in a sector comprehensively by effectively using radio resources.

  In a digital wireless communication system, even if a time delay required for transmission, such as the Internet, is allowed rather than a communication with a small transmission delay while allowing a certain amount of transmission error, such as conventional real-time voice communication, There is an increasing demand for reliable and high-speed data communication.

  Examples that embody these are communications such as W-CDMA (Wide Band-Code Division Multiple Access), third-generation mobile phone (3G) mobile communication systems represented by CDMA2000, WiMAX (Worldwide Interoperability for Microwave Access), etc. It is a method.

  In these systems, a wide area to be operated is divided into sectors, and radio base stations (BSs) are arranged so as to cover each sector. And communication with the mobile radio | wireless terminal (MS: Mobile Station) arrange | positioned in each sector is implement | achieved.

  Also, the quality of the radio transmission signal from the BS differs depending on the arrangement of the MS. Due to the difference in the radio quality, the MS is divided into two groups (a cell center group that satisfies the radio quality standard value and a radio quality standard value that does not meet the radio quality standard value). There is a technology called FFR (Fractional Frequency Resource), which is divided into cell edge groups), in which independent radio resources are allocated to each group, and the MSs in each group share radio resources.

[Conventional wireless transceiver: FIG. 2]
Next, a conventional wireless transmission / reception apparatus will be described with reference to FIG. FIG. 2 is a block diagram showing a configuration of a conventional wireless transmission / reception apparatus.
The wireless transmission / reception device 200 corresponds to a BS, and the wireless transmission / reception device 300 corresponds to an MS.

[Conventional wireless transceiver (transmission function)]
As shown in FIG. 2, the transmission function in the conventional wireless transmission / reception apparatus includes a scheduler 201, a primary modulation unit 202, an OFDM (Orthogonal Frequency Division Multiplexing) modulation unit 203, an RF unit 204, It has an antenna 205, an OFDM demodulator 206, a C / N information detector 207, a C / N information smoother 208, a cell edge determiner 209, and a cell edge determination threshold storage unit 210.

[Conventional wireless transceiver (reception function)]
As shown in FIG. 2, the reception function in the conventional wireless transmission / reception apparatus includes an antenna 301, an RF unit 302, an OFDM demodulation unit 303, a C / N detection unit 304, a primary modulation unit 305, and an OFDM modulation unit. 306.

[Operations in a conventional wireless transceiver]
The transmission data addressed to one or more MSs is input to the schedule 201, and the transmission data addressed to the determined MS is output to the primary modulation unit 202 according to the scheduling method.
Primary modulation section 202 receives transmission data and outputs a primary modulation signal for each subcarrier.
The OFDM modulation unit 203 performs orthogonal transform from a frequency signal to a time axis signal by inverse fast Fourier transform (IFFT), converts the signal into a radio frequency signal by the RF unit 204 as a baseband signal, and performs antenna conversion. A spatial output is made by 205.

  In radio transceiver 300 corresponding to MS, radio frequency signal is received by antenna 301, converted to a baseband signal by RF unit 302, and sub-processed by fast Fourier transform (FFT) by OFDM demodulator 303. It converts into a reception modulation signal for every carrier, demodulates, and outputs reception data.

  In addition, the C / N detection unit 304 of the wireless transmission / reception apparatus 300 measures the quality of the received modulation signal and notifies the primary modulation unit 305 of C / N information in the MS direction (downlink direction) from the BS. The notified C / N information and transmission data in the BS direction (uplink direction) from the MS are subjected to primary modulation, and a primary modulation signal for each subcarrier is output to the OFDM modulation section 306.

  The OFDM modulation unit 306 performs orthogonal transform from a frequency signal to a time axis signal by FFT to obtain a baseband signal, converts it to a radio frequency signal by the RF unit 302, and performs spatial output in the uplink direction from the antenna 301.

  The spatial output in the uplink direction is received by the antenna 205 of the radio transmission / reception apparatus 200 corresponding to the BS, converted into a baseband signal by the RF unit 204, and per-subcarrier in the uplink direction by the OFDM demodulation unit 206 by FFT. It is converted into a frequency signal, demodulated and output as received data. Further, the C / N information detection unit 207 detects C / N information in the downlink direction detected by the MS.

[Cell edge judgment method]
Next, a cell edge determination method will be described.
First, the cell edge determination unit 209 of the wireless transmission / reception apparatus 200 acquires the cell edge determination threshold held by the cell edge determination threshold holding unit 210.
The C / N information smoothing unit 208 smoothes the C / N information from the C / N information detection unit 207 for each MS, and outputs the smoothed C / N information to the cell edge determination unit 209.

  The cell edge determination unit 209 compares the smoothed C / N information for each MS and the cell edge determination threshold value. When the smoothed C / N information <the cell edge determination threshold value, the cell edge determination unit 209 determines that the MS is a cell edge group and performs smoothing C When / N information ≧ cell edge determination threshold value, the MS is determined to be a cell center group. The determination result is notified to the scheduler 201 and used for scheduling.

[Configuration of adjacent sector: FIG. 3]
The configuration of adjacent sectors will be described with reference to FIG. FIG. 3 is a configuration diagram of adjacent sectors.
FIG. 3 shows an adjacent sector arrangement when the cell is divided into three sectors by the sector antenna. This figure represents that the same sector is not adjacent.

[Distribution example of cell edge group and cell center group: FIG. 4]
The distribution of the cell edge group and the cell center group will be described with reference to FIG. FIG. 4 is a diagram illustrating a distribution example of cell edge groups and cell center groups.
The cell edge groups are distributed in areas far from the BS and out of the center of the sector antenna. The cell center group is distributed in a region close to the BS and close to the center direction of the sector antenna.

[Radio frame configuration: Fig. 5]
Next, a radio frame configuration will be described with reference to FIG. FIG. 5 is a configuration diagram of a radio frame.
The radio frame shown in FIG. 5 shows an example of use of the OFDM mapping area when FFR is applied. The vertical axis is the frequency axis, the horizontal axis is the time axis, and FIG. 5 shows the case of the TDD (Time Division Duplex) method, where the downlink subframe section is the transmission section from the BS to the MS, the uplink A frame section indicates a transmission section from the MS to the BS.

Further, the preamble section is a section in which information for the MS to establish radio synchronization with the BS is transmitted.
The MAP information section is a section in which a control message such as data burst arrangement information is transmitted to all MSs in the sector.
The cell edge section is a section in which data bursts to be transmitted to the cell edge MS are arranged.
The cell center section is a section in which data bursts to be transmitted to the cell center MS are arranged.

[Downlink subframe: Fig. 6]
Details of the downlink subframe will be described with reference to FIG. FIG. 6 is a diagram illustrating a usage example of the downlink subframe of each sector. In particular, (a) shows an example of use of a downlink subframe of sector 1, (b) shows an example of use of a downlink subframe of sector 2, and (c) shows a downlink subframe of sector 3 An example of using is shown.
FIG. 6 shows a method of using a downlink subframe section of 3 sectors.
As shown in FIG. 6, the MAP information section and the cell edge section use the respective areas obtained by dividing the entire band into three equal parts, and the cell center section uses the entire band in common with the three sectors. Yes.

The cell edge group is easily affected by interference with the transmission signal of the adjacent sector BS depending on the arrangement condition. In order to avoid the interference, a frequency band that does not compete with adjacent sectors is used.
The cell center group is not easily affected by interference with the transmission signal of the adjacent sector BS due to the arrangement condition. Therefore, a common frequency band is used between adjacent sectors.

As can be seen from FIG. 6, since the data burst transmission sections of the cell edge group and the cell center group are independent, the total transmission rate of each group is distributed among the MSs of each group according to the specifications of the scheduler 201. .
In addition, in order to satisfy the communication quality (in this case, the minimum guaranteed transmission rate) expected by the operator operating the system, the ratio between the cell edge section and the cell center section is adjusted, or the cell edge The determination threshold is adjusted.

As a related prior art, there is JP-A-2007-258844 (Patent Document 1).
In Patent Literature 1, in a radio access network apparatus, it is determined whether a mobile station belongs to a cell edge region, a cell edge frequency is assigned to a cell edge mobile station, and a cell edge is assigned to a user in a region other than the cell edge. It is described that a non-cell edge frequency different from the frequency is assigned.

JP 2007-258844 A

However, the conventional wireless transmission / reception apparatus has the following problems.
The MS is determined to be either a cell edge group or a cell center group based on the radio quality determined from the arrangement in the sector and the cell edge determination threshold. Also, considering that the MS moves, the number of MSs in the cell edge group and the number of MSs in the cell center group are not always constant and change with time.

  Therefore, even if the cell edge determination threshold is determined and used based on the assumption of the number of MSs in the cell, the MS arrangement, and the minimum guaranteed transmission rate, the number of MSs in each group that changes from moment to moment and the sector in each MS Since the optimum cell edge determination threshold varies with respect to the arrangement, there may be a case where the minimum guaranteed transmission rate cannot be satisfied.

Specifically, an example in which the cell edge determination threshold is fixed to 16 in the middle when the C / N information (CQI) is set to 32 levels will be described. At the same time, it is assumed that all MSs in the sector are located at remote locations where they can barely communicate with the BS. That is, it is assumed that all MSs are arranged at the cell edge.
At that time, the wireless communication quality is poor, and the CQI notified from all MSs to the BS is around 2-6.

Then, since the CQI is lower than the cell edge determination threshold, all the MSs enter the cell edge group. Then, the radio resources of the cell center group are not used.
At this time, the required radio resources are biased only to the cell edge group, and the radio resources in the cell edge group are insufficient and the minimum guaranteed rate cannot be satisfied.

Also, the optimal cell edge determination threshold is, for example, when there are 10 MSs in a sector, and it is desired to divide 5 radio resources into each group and to divide radio resources on average (assuming the rate at that time is desired) ).
At that time, if the cell edge determination threshold is set to 4 in the above example, the cell is roughly divided into about half and the bias of radio resources required for the entire cell is eliminated.

  As a conventional coping method, there is a method of limiting the number of MSs so that the minimum guaranteed transmission rate that is an index can be satisfied even when the ratio of the number of MSs in each group is biased. However, in the coping method, a margin corresponding to the worst condition is always ensured during operation, so that the maximum transmission rate that can be realized with respect to the total transmission rate is lowered.

  The present invention has been made in view of the above circumstances, and can satisfy the minimum guaranteed transmission rate specified for each of the cell edge group and the cell center group, and can effectively utilize radio resources, An object of the present invention is to provide a wireless transmission / reception apparatus capable of comprehensively improving the transmission rate of MS.

  The present invention for solving the problems of the above-described conventional example is a radio transmission / reception apparatus used in a digital radio system in which a plurality of radio base stations are adjacent in a cell structure, and the radio base station manages a plurality of mobile radio terminals The mobile radio terminal uses a communication method that occupies a time domain and a frequency band exclusive to neighboring cells, and schedules transmission data addressed to the mobile radio terminal in a transmission frame. A scheduler, a cell edge determination threshold holding unit for holding a cell edge determination threshold, a mobile radio terminal is classified into a cell edge group and a cell center group according to a cell edge determination threshold, and the number of mobile radio terminals in the cell edge group is detected. A cell edge determination unit that detects the number of mobile wireless terminals in the central group and outputs the detected number to the scheduler, and a cell edge A minimum transmission rate detector that detects the minimum transmission rate of the mobile radio terminal in the group and detects the minimum transmission rate of the mobile radio terminal in the cell center group, and the minimum guaranteed transmission rate and cell center specified in the cell edge group Minimum guaranteed transmission rate holding unit that holds the minimum guaranteed transmission rate specified for the group, the cell edge determination threshold calculation formula according to the number of mobile radio terminals in the cell edge group and the number of mobile radio terminals in the cell center group, and detection And a cell edge determination threshold updating unit that calculates a cell edge determination threshold using the minimum transmission rate and the stored minimum guaranteed transmission rate, and updates the cell edge determination threshold of the cell edge determination threshold holding unit.

  According to the present invention, the scheduler schedules transmission data addressed to the mobile radio terminal in a transmission frame, the cell edge determination threshold holding unit holds the cell edge determination threshold, and the cell edge determination unit determines whether the mobile radio terminal is based on the cell edge determination threshold. The cell edge group and the cell center group are classified, the number of mobile radio terminals in the cell edge group is detected, the number of mobile radio terminals in the cell center group is detected and output to the scheduler, and the minimum transmission rate detection unit, The minimum transmission rate of the mobile radio terminal in the cell edge group is detected, the minimum transmission rate of the mobile radio terminal in the cell center group is detected, and the cell edge determination threshold update unit specifies the minimum guaranteed transmission rate specified for the cell edge group And the minimum guaranteed transmission rate that holds the minimum guaranteed transmission rate specified for the cell center group. Cell edge determination threshold calculation formula according to the number of mobile radio terminals in the cell edge group and the number of mobile radio terminals in the cell center group, and the detected minimum transmission rate and the held minimum guaranteed transmission rate. Since the wireless transmission / reception apparatus calculates the determination threshold and updates the cell edge determination threshold of the cell edge determination threshold holding unit, the minimum guaranteed transmission rate specified for each of the cell edge group and the cell center group can be satisfied. There is an effect that it is possible to improve the transmission rate of MSs in a sector comprehensively by effectively utilizing resources.

[Outline of the embodiment]
Embodiments of the present invention will be described with reference to the drawings.
The radio transmitting / receiving apparatus according to the embodiment of the present invention monitors the communication status of the cell edge group and the cell center group, detects the minimum guaranteed transmission rate of each mobile radio terminal (MS) in each group, and the detection result And the minimum guaranteed transmission rate set as an index for each group, respectively, update the cell edge determination threshold so that the detected transmission rate satisfies the set minimum guaranteed transmission rate, and the updated optimum cell edge determination The cell edge is determined based on the threshold value, and communication is performed.

[Change in cell edge determination threshold and change in area of each group: FIG. 7]
Before describing the radio transmission / reception apparatus according to the embodiment of the present invention, a change in the size of the cell center group area and the cell edge group area with respect to a change in the cell edge determination threshold will be described with reference to FIG. FIG. 7 is a diagram illustrating changes in the cell edge determination threshold and changes in the area of each group.

As shown in FIG. 7, when the cell edge determination threshold value is small, the area of the cell center group is relatively wide and the area of the cell edge group is relatively narrow.
Further, when the cell edge determination threshold value is increased, the area of the cell edge group becomes relatively wide and the area of the cell center group becomes relatively narrow.

[Basic idea]
In the embodiment of the present invention, there are two control target values for the cell edge determination threshold update function: the cell edge minimum guaranteed transmission rate and the cell center minimum guaranteed transmission rate.
The number of MSs in the cell edge group and the cell center group is only a result under the conditions of the updated cell edge determination threshold and the MS arrangement in the sector, and is not a control target.

  Actually, the transmission rate varies depending on radio quality, adaptive modulation, and power control. However, as the number of users increases as resources are divided, the resources allocated per person are equally divided. Therefore, the control target is satisfied by changing the grouping of MSs.

  In other words, it is not to keep the number of MSs per group constant, but only to satisfy the minimum guaranteed transmission rate. By controlling grouping, radio resources are optimized, and the MS transmission rate in the sector is Overall improvement.

  Furthermore, when the minimum guaranteed transmission rate at the cell edge or the cell center is not satisfied, the cell edge determination threshold is updated to change the grouping of the MS, and the bias between the groups of required radio resources is eliminated. The minimum guaranteed transmission rate is maintained such that the transmission rate satisfies the minimum guaranteed transmission rate.

A radio transmission / reception apparatus according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a configuration block diagram of a radio transmission / reception apparatus according to an embodiment of the present invention. Since the configuration of the MS is the same as in FIG. 2, only the BS will be described in FIG.
As shown in FIG. 1, a wireless transmission / reception apparatus (this apparatus) according to an embodiment of the present invention includes a scheduler 101, a primary modulation unit 102, an OFDM modulation unit 103, an RF unit 104, an antenna 105, OFDM demodulation unit 106, C / N information detection unit 107, C / N information smoothing unit 108, cell edge determination unit 109, cell edge determination threshold value holding unit 110, minimum transmission rate detection unit 111, and minimum guaranteed transmission The rate holding unit 112, the update step holding unit 113, and the cell edge determination threshold update unit 114 are basically included.

  The primary modulation unit 102, OFDM modulation unit 103, RF unit 104, antenna 105, OFDM demodulation unit 106, C / N information detection unit 107, and C / N information smoothing unit 108 shown in FIG. The same configuration as the BS primary modulation section 202, OFDM modulation section 203, RF section 204, antenna 205, OFDM demodulation section 206, C / N information detection section 207, and C / N information smoothing section 208 shown in FIG. Therefore, the description is omitted.

[Each part]
The cell edge determination unit 109 acquires the cell edge determination threshold held by the cell edge determination threshold holding unit 110, inputs the smoothed C / N information from the C / N information smoothing unit 108, and performs smoothing C for each MS. / N information is compared with the cell edge determination threshold. When smoothing C / N information <cell edge determination threshold, the MS is determined to be a cell edge group. When smoothing C / N information ≧ cell edge determination threshold, The MS is determined to be a cell center group. The determination result is notified to the scheduler 101 and used for scheduling.
In addition, the cell edge determination unit 109 notifies the cell edge determination threshold update unit 114 of the number of cell edge MSs and the number of cell center MSs.

The scheduler 101 inputs transmission data for one or more MSs, and outputs the transmission data for the determined MS to the primary modulation unit 102 according to the scheduling method.
Also, the scheduler 101 outputs the transmission rate of each MS and outputs it to the minimum transmission rate detection unit 111.
Since the scheduler 101 has a function of managing the transmission opportunity and transmission data amount of each MS, it is possible to output the transmission rate of each MS.

  The lowest transmission rate detection unit 111 detects the lowest transmission rate of the MS in the cell edge group and the lowest transmission rate of the MS in the cell center group from the transmission rates of all the MSs, and notifies the cell edge determination threshold update unit 114 of them.

  The cell edge determination threshold update unit 114 calculates a new cell edge determination threshold using a cell edge determination threshold calculation formula according to the case classification of the cell edge MS number and the cell center MS number, and calculates the value of the cell edge determination threshold holding unit 110 Update with results. A method for calculating the cell edge determination threshold will be described later.

  The cell edge determination threshold value holding unit 110 stores a cell edge determination threshold value. Initially, an initial value is set, but thereafter, the cell edge determination threshold value update unit 114 is updated.

  The minimum guaranteed transmission rate holding unit 112 stores the minimum guaranteed transmission rate values specified for the cell edge group and the cell center group, and outputs the minimum guaranteed transmission rate value to the cell edge determination threshold update unit 114. To do. The minimum guaranteed transmission rate holding unit 112 also stores a minimum guaranteed transmission rate 2 described later.

  The update step holding unit 113 stores information related to the update step, an update reference amount for updating the cell edge determination threshold (including the update reference amount 2), and an update of the cell edge determination threshold described later. The weight coefficient 2 is stored and output to the cell edge determination threshold update unit 114.

[Operation]
This device is used in a digital radio system in which a plurality of base stations (BS) are adjacent in a cell structure, and one BS manages a plurality of mobile stations (MS) to transmit and receive data. The cell edge group is classified into a cell edge group and a cell center group according to the value (cell edge determination threshold), and the MS uses the FFR method that occupies a time domain and a frequency band exclusive to neighboring cells, and sets the number of MSs in the cell edge group. Detect and detect the number of MSs in the cell center group, calculate the minimum transmission rate of the MSs in the cell edge group, calculate the minimum transmission rate of the MSs in the cell center group, The cell edge determination threshold value is calculated and updated using the cell edge determination threshold value calculation formula corresponding to the number of MSs, and the cell edge determination threshold value is used to update the cell edge determination threshold value. A judgment, performs scheduling of transmission data in the scheduler.

[Cell edge MS: 1 or more, Cell center MS: 1 or more]
When the number of MSs in the cell edge group is 1 or more (1 cell edge MS or more) and the number of MSs in the cell center group is 1 or more (1 cell center MS or more), the cell edge determination threshold is updated using Equation 1 and Equation 2. To do.

[Formula 1]
Weight coefficient = 10 × log ₁₀ ([cell edge minimum transmission rate / cell center minimum transmission rate] × [cell center minimum guaranteed transmission rate / cell edge minimum guaranteed transmission rate]) (Expression 1)
[Formula 2]
Cell edge determination threshold (t + 1) = cell edge determination threshold (t) + update reference amount × weighting coefficient (Expression 2)

  Equation 1 calculates the sum of the ratio of the minimum transmission rate between the cell edge and the cell center and the ratio of the minimum guaranteed transmission rate between the cell edge and the cell center as a weighting factor for the amount of variation when updating the cell edge determination threshold. Yes.

  Formula 2 adds the multiplication result of the update reference amount, which is a control parameter, and the weighting coefficient calculated in Formula 1 to the cell edge determination threshold. This calculation represents updating the cell edge determination threshold in a direction to cancel the difference between the minimum transmission rate and the minimum guaranteed transmission rate.

The specific update of the cell edge determination threshold and the MS variation of the cell edge / cell center group will be described. Note the following relationship in Equation 1:
[Relational expression 1]
(Cell edge minimum transmission rate / cell center minimum transmission rate): (cell center minimum guaranteed transmission rate / cell edge minimum guaranteed transmission rate) (1)

First, since the cell center minimum guaranteed transmission rate and the cell edge minimum guaranteed transmission rate are setting parameters, they can be regarded as fixed values during the update process.
Therefore, the variable that affects the update of the cell edge determination threshold is the minimum transmission rate of each group measured during the update process calculation.

Therefore, the cause of fluctuations in the cell edge minimum transmission rate and the cell center minimum transmission rate and the update operation of the cell edge determination threshold will be described.
The case where the cell edge minimum transmission rate is lowered means that the number of MSs in the cell edge group is increased in order to maintain the expected transmission guaranteed rate. For this reason, the cell edge determination threshold is updated in the direction of decreasing. Then, the MS with relatively good radio communication quality that belonged to the cell edge group moves to the cell center group, and accordingly, it becomes possible to allocate radio resources to the MS with poor radio quality of the cell edge group. Thereby, the effect of increasing the minimum transmission rate of the cell edge group can be obtained.

  Contrary to the above, when the cell edge minimum transmission rate increases, it can be said that it is possible to allocate more radio resources than the expected transmission guaranteed rate to the MS of the current cell edge group. . Therefore, the cell edge determination threshold is increased until the expected transmission guarantee rate is reached, and the cell edge group is updated in the direction of increasing the MS.

  Up to this point, the case where the minimum transmission rate is increased or decreased for the cell edge has been described. As is clear from Equation 1, the minimum transmission rate is calculated as a ratio, and the cell center minimum transmission rate is also calculated for the cell edge group. The opposite effect and influence can be obtained.

[Cell edge MS: 0 units, Cell center MS: 1 unit or more]
When the number of cell edge MSs is zero and the number of cell center MSs is one or more, there is a goal of transitioning the cell center MS to a cell edge group and improving the use efficiency of radio resources. For this purpose, it is necessary to change the cell edge determination threshold value in a lowering direction.

However, the transition from the existing cell center MS to the cell edge group and transmission in the cell edge section does not uniquely lead to an improvement in the transmission rate of the MS itself.
Therefore, when the minimum transmission rate is greater than the minimum guaranteed transmission rate 2 as compared with the current cell center minimum transmission rate and the minimum guaranteed transmission rate 2 in which the maximum transmission rate when the cell edge section is occupied by one MS is set. When the minimum transmission rate is equal to or lower than the minimum guaranteed transmission rate 2 using Equation 3, the cell edge determination threshold is updated using Equation 4.

[Formula 3]
When the minimum transmission rate of the cell center group> the minimum guaranteed transmission rate 2 of the cell center group, the cell edge determination threshold value (t + 1) = the cell edge determination threshold value (t).
[Formula 4]
Cell edge determination threshold (t + 1) = cell edge determination threshold (t) + update reference amount 2 when cell center group minimum transmission rate ≦ cell center group minimum guaranteed transmission rate 2 Equation 4

The update reference amount 2 is a control step for increasing the cell edge determination threshold in order to shift the MS of the cell center group to the cell edge group.
The update reference amount is used in the above equation 2, and even if the update reference amount 2 in equation 4 and the update reference amount in equation 2 are the same value, there is no problem in the nature of the invention. The condition for updating the cell edge determination threshold value may be different, and in order to allow a different value to be used as the control value for the update step of the cell edge determination threshold value depending on the condition, Expression 4 is defined with another parameter. .

Expression 3 represents that the cell edge determination threshold is not changed because the cell center MS satisfies the minimum guaranteed transmission rate 2.
Since the cell center MS does not satisfy the minimum guaranteed transmission rate 2, Equation 4 represents an operation of increasing the cell edge determination threshold and shifting the cell center MS communicating at the minimum transmission rate to the cell edge group.

[Cell edge MS: 1 or more, Cell center MS: 0]
When the number of cell edges MS is one or more and the number of cell centers MS is zero, the cell edge determination threshold is updated using Equation 5.
[Formula 5]
Cell edge determination threshold (t + 1) = cell edge determination threshold (t) −weighting factor 2 × (cell edge determination threshold (t) −cell edge determination threshold (0)).
Although there is no problem even if the weighting coefficient of Expression 2 = weighting coefficient 2 of Expression 5, Expression 5 is defined with another parameter in order to allow control with different values.

  Expression 5 multiplies the difference between the cell edge determination threshold before update and the initial value of the cell edge determination threshold (cell edge determination threshold (0)) by the weighting factor 2, and adds the result to the cell edge determination threshold before update. This calculation is an operation for returning the cell edge determination threshold to the initial value with the weighting factor 2 of the transmission rate as a time constant.

[Effect of the embodiment]
According to the present apparatus, it is possible to update the cell edge determination threshold according to the MS arrangement in the sector that changes with time and satisfy the minimum guaranteed transmission rate specified for each of the cell edge group and the cell center group. The wireless resource (time and frequency) can be effectively utilized to improve the transmission rate of MSs in the sector comprehensively.

  The present invention can satisfy the minimum guaranteed transmission rate specified for each of the cell edge group and the cell center group, and can effectively improve the transmission rate of MSs in the sector by effectively using radio resources. This is suitable for a wireless transmission / reception device capable of transmitting data.

1 is a configuration block diagram of a wireless transmission / reception apparatus according to an embodiment of the present invention. It is a block diagram of a conventional radio transceiver apparatus. It is a block diagram of an adjacent sector. It is a figure which shows the example of distribution of a cell edge group and a cell center group. It is a radio | wireless frame block diagram. It is a figure which shows the usage example of the downlink sub-frame of each sector. It is a figure which shows the change of the cell edge determination threshold value, and the change of the area of each group.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100,200 ... Base station (BS) 101, 201 ... Scheduler, 102, 202 ... Primary modulation part, 103, 203 ... OFDM modulation part, 104, 204 ... RF part, 105, 205 ... Antenna, 106, 206 ... OFDM demodulating section 107, 207 ... C / N information detecting section 108, 208 ... C / N information smoothing section 109, 209 ... cell edge judging section 110, 210 ... cell edge judging threshold holding section 111 ... lowest transmission rate Detection unit 112 ... Minimum guaranteed transmission rate holding unit 113 113 Update step holding unit 114 ... Cell edge determination threshold update unit 300 ... Mobile wireless terminal (MS) 301 ... Antenna 302 ... RF unit 303 ... OFDM demodulation unit 304 ... C / N detector, 305 ... primary modulator, 306 ... OFDM modulator

Claims (1)

A wireless transceiver used in a digital wireless system in which a plurality of wireless base stations are adjacent in a cell structure,
The radio base station manages a plurality of mobile radio terminals to transmit and receive data, and the mobile radio terminals use a communication method that occupies an exclusive time domain and frequency band for neighboring cells,
A scheduler for scheduling transmission data addressed to a mobile radio terminal in a transmission frame;
A cell edge determination threshold holding unit for holding a cell edge determination threshold;
The mobile radio terminals are classified into a cell edge group and a cell center group according to a cell edge determination threshold, the number of mobile radio terminals in the cell edge group is detected, and the number of mobile radio terminals in the cell center group is detected and output to the scheduler A cell edge determination unit to perform,
A minimum transmission rate detector for detecting a minimum transmission rate of mobile radio terminals in a cell edge group and detecting a minimum transmission rate of mobile radio terminals in a cell center group;
A minimum guaranteed transmission rate holding unit for holding the minimum guaranteed transmission rate specified for the cell edge group and the minimum guaranteed transmission rate specified for the cell center group;
Cell edge determination using the cell edge determination threshold value calculation formula according to the number of mobile radio terminals in the cell edge group and the number of mobile radio terminals in the cell center group, the detected minimum transmission rate and the held minimum guaranteed transmission rate A wireless transmission / reception apparatus comprising: a cell edge determination threshold update unit that calculates a threshold and updates a cell edge determination threshold of the cell edge determination threshold holding unit.

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