JP5545785B1 - Wireless network control device and bandwidth distribution control method - Google Patents

Abstract

A radio network control apparatus capable of shifting a mobile device to an appropriate standby band at the end of a call.
According to one aspect of the present invention, a different frequency measurement value indicating a communication quality of a transitionable band measured by the mobile device while the different frequency measurement mode is activated by shifting the mobile device to a different frequency measurement mode. A different frequency measurement starting unit for acquiring and storing, a throughput estimating unit for estimating a throughput of the transitionable band when it is determined that the mobile device should enter an idle mode, and the stored different frequency measurement value Further, the present invention relates to a radio network control device having a standby bandwidth determination unit that determines a standby bandwidth that a mobile device that has shifted to the idle mode should be in based on the estimated throughput.
[Selection] Figure 4

Description

  The present invention relates to a wireless communication system.

  Mobile devices that can communicate in a plurality of bands or bands are widely used. In a wireless communication system capable of multiband communication, when a mobile device ends a call or data communication, the wireless network control device can control in which band the mobile device that enters the idle mode is awaited. is there.

  One of the mobile station control methods at the end of such a call is traffic distributed control. In the traffic distribution control, when a mobile station finishes talking, the radio network controller causes the serving base station and neighboring base station of the mobile station to report the free capacity of each band, and based on the reported free capacity, Estimate the throughput that indicates the communication capability. When the throughput of each band is calculated, the wireless network control device shifts the mobile device to a bandwidth that has a large free capacity and can be expected to have a high throughput, and instructs the mobile device to wait in that bandwidth. Such traffic distribution control makes it possible to distribute traffic over the entire system band.

JP2011-091587

  In the traffic distribution control described above, the radio network controller calculates the throughput from the free capacity of each band, and determines the standby band or standby cell of the mobile device based on the calculated throughput.

  However, there is a case where a band for which high throughput is expected does not necessarily have good communication quality. In this case, the mobile device waits in a band that does not have sufficient communication quality, and when the communication is resumed, the mobile device must perform cell search or handover from the standby bandwidth, and communication is temporarily performed. Possible instability.

  For example, in the conventional traffic distribution control, as shown in FIG. 1, when a mobile device capable of communicating in each band of 800 MHz, 1.7 GHz, and 2 GHz ends, the wireless network control device is the highest The mobile device is instructed to stand by in the 800 MHz band where the throughput is expected. However, since the communication quality in each band is not considered in the conventional traffic distribution control, there is a possibility that the mobile device waits in a band of 800 MHz where the communication quality is not sufficient.

  In view of the above problems, an object of the present invention is to provide a wireless network control device capable of shifting a mobile device to an appropriate standby band at the end of a call.

  In view of the above-described problems, an aspect of the present invention is to perform a different frequency measurement that indicates a communication quality of a transitionable band measured by the mobile device during the activation of the different frequency measurement mode by shifting the mobile device to the different frequency measurement mode. A different frequency measurement starting unit for acquiring and storing a value; a throughput estimating unit for estimating a throughput of the transitionable band when the mobile device is to be shifted to an idle mode; and the stored different frequency measurement. The present invention relates to a radio network controller having a standby bandwidth determination unit that determines a standby bandwidth that a mobile device that has shifted to the idle mode should be in based on a value and the estimated throughput.

  ADVANTAGE OF THE INVENTION According to this invention, the radio | wireless network control apparatus which can change a mobile apparatus to a suitable standby zone | band at the time of a call end can be provided.

FIG. 1 is a schematic diagram of conventional band dispersion control. FIG. 2 is a schematic diagram of band dispersion control according to an embodiment of the present invention. FIG. 3 is a schematic diagram of a wireless communication system according to an embodiment of the present invention. FIG. 4 is a block diagram showing a configuration of a radio network controller according to an embodiment of the present invention. FIG. 5 is a block diagram showing the configuration of the standby bandwidth determination unit according to an embodiment of the present invention. FIG. 6 is a flowchart showing band dispersion control processing according to an embodiment of the present invention. FIG. 7 is a flowchart showing a standby bandwidth determination process according to an embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  To summarize an embodiment described later, the radio network controller acquires and stores a different frequency measurement value indicating a communication quality of a band in which a mobile station can be measured, which is measured while the different frequency measurement mode is activated. When the mobile device shifts to the idle mode due to the end of a call or the completion of data communication, the wireless network control device extracts a band that exceeds a predetermined threshold value from the stored different frequency measurement value, and the throughput is maximized from the extracted band. The band that becomes is determined as the standby band.

  For example, in the embodiment shown in FIG. 2, the radio network controller extracts a band (2 GHz and 1.7 GHz) that is equal to or higher than a predetermined threshold, and determines the extracted band as a band with good communication quality. Thereafter, the wireless network control device determines a band (2 GHz) having a larger throughput among the extracted bands as a standby band, and notifies the mobile station of the standby band. When the notification is received, the mobile device enters a standby state in the notified band.

  Even in the compressed mode implemented for different frequency handover, since the report of the measurement result is a periodic report, the radio network controller holds the measurement result of each band even before the implementation of the different frequency handover. Using this measurement result for band dispersion control, it is possible to adjust whether to place importance on the traffic dispersion effect or the user quality at the time of communication return, allowing the mobile station to stand by in the best cell To. Here, “before implementation” of the different frequency handover means the different frequency measurement performed to determine whether or not the handover is executed. In this way, a predetermined communication quality can be obtained by using not only the free capacity or throughput of each band as in the conventional band dispersion control but also using different frequency measurement values acquired from the mobile device during the activation of the different frequency measurement mode. It is possible to transition to a high-bandwidth standby band that guarantees In this way, by using the different frequency measurement values acquired for determining whether or not handover is necessary during communication for bandwidth distribution control, it is possible to determine a standby band with good communication quality while suppressing additional costs. It becomes possible to do.

  A radio communication system according to an embodiment of the present invention will be described with reference to FIG. FIG. 3 is a schematic diagram of a wireless communication system according to an embodiment of the present invention.

  As illustrated in FIG. 3, the wireless communication system 10 includes a wireless network control device 100, base stations 201, 202, 203, and a mobile device 300.

  The radio network controller 100 is connected to a plurality of base stations 201, 202, and 203, and controls radio communication of the mobile device 300 via the serving base station 201 in the illustrated example. The wireless network control device 100 is connected to various upper network devices (not shown). The radio network controller 100 performs various radio communication processes such as outgoing / incoming control, radio resource scheduling, line connection, and handover control with respect to the mobile device 300 via the serving base station 201. The wireless network control device 100 is configured by hardware resources such as a processor, a memory, and a communication circuit, for example, and various wireless communication processes including functions and processes described later when the processor executes a program stored in the memory. Can be realized.

  The base stations 201, 202, and 203 provide one or more cells or bands for wireless communication, and wirelessly connect to the mobile device 300 through these bands under the control of the wireless network control device 100. For example, the base stations 201, 202, and 203 provide 1.7 GHz, 800 MHz, and 2 GHz bands, respectively, and can communicate with the mobile device 300 located in these bands. In the illustrated embodiment, the mobile device 300 uses the 1.7 GHz band provided by the base station 201 as a serving cell. In this embodiment, each of the base stations 201, 202, and 203 provides one band. However, the present invention is not limited to this, and one base station may provide a plurality of bands. In the present embodiment, the base stations 201, 202, and 203 adjacent to each other provide different frequency bands. However, the present invention is not limited to this, and it is necessary to avoid the occurrence of interference between base stations. However, the same or partially overlapping frequency bands may be provided.

  The mobile device 300 communicates with the base stations 201, 202, and 203 by radio. In addition, the mobile device 300 supports a multiband communication function and can perform communication in a plurality of bands provided by the base stations 201, 202, and 203.

  In the radio communication system 10, the radio network controller 100 causes the mobile device 300 to perform different frequency measurement in order to determine whether or not handover is necessary. Specifically, the radio network controller 100 shifts the mobile device 300 to the compressed mode in response to a predetermined trigger such as that the communication quality of the serving base station 201 falls below a predetermined threshold. In the compressed mode, the mobile device 300 temporarily stops transmission in the idle slot period (transmission gap) during communication with the serving base station 201, and measures the reception level of the different frequency band in the transmission gap ( The measurement result is reported to the radio network controller 100 via the serving base station 201.

  In the illustrated embodiment, when entering the compressed mode, the mobile station 300 communicating with the serving base station 201 sets the reception level or communication quality of the different frequency bands provided by the neighboring base stations 202 and 203 in the transmission gap. taking measurement. Based on the measurement result reported from the mobile device 300, the radio network controller 100 compares the communication quality of the serving cell with the measurement result of the different frequency band, and determines whether to hand over the mobile device 300 from the serving cell. When instructed to perform handover from the serving cell, the mobile device 300 executes a handover process under the control of the radio network control apparatus 100, and transitions to the designated target cell.

  Next, with reference to FIGS. 4-5, the structure of the radio | wireless network control apparatus by one Example of this invention is demonstrated. In this embodiment, when the mobile device 300 shifts to the idle mode when the mobile device 300 is at the end of the call or the like, the radio network control device 100 detects the different frequency measurement result reported from the mobile device 300 during the compressed mode, and the mobile device 300 Using the available capacity of the transitionable band and / or the throughput of each band calculated from the measurement result of different frequencies, the standby band of the mobile station 300 is determined, and the mobile station 300 transitions to the determined standby band. To instruct.

  FIG. 4 is a block diagram showing a configuration of a radio network controller according to an embodiment of the present invention. As illustrated in FIG. 4, the radio network control device 100 includes a different frequency measurement activation unit 110, a throughput estimation unit 120, and a standby band determination unit 130.

  The different frequency measurement activation unit 110 shifts the mobile device 300 to the different frequency measurement mode in order to determine whether handover is necessary, and the reception level of the transitionable band measured by the mobile device 300 during the activation of the different frequency measurement mode. Alternatively, a different frequency measurement value indicating communication quality is acquired and stored. The different frequency measurement mode is also called a compressed mode, and the different frequency measurement activation unit 110 determines whether or not handover is necessary, for example, when the reception level of the serving cell is lowered. The radio network controller 100 instructs the mobile device 300 to start the compressed mode and transmits information necessary for causing the mobile device 300 to measure the different frequency bands of the neighboring base stations 202 and 203.

  In the compressed mode, the radio network controller 100 temporarily stops data transmission in a partial section (transmission gap) of a frame transmitted from the serving base station 201 to the mobile device 300, and during that time, the band over destination The mobile device 300 measures the reception level of the different frequency band that is a candidate for the above. The mobile device 300 transmits the measured reception level or communication quality of the different frequency band to the radio network controller 100 via the serving base station 201 as the different frequency measurement result. The radio network controller 100 determines whether or not handover is necessary based on the received different frequency measurement result, and in the present embodiment, the different frequency measurement activation unit 110 uses the received different frequency for the subsequent band dispersion control. Stores measurement results. For example, the different frequency measurement result may indicate a reception level such as Ec / N0 in the measurement target band.

  When the throughput estimation unit 120 detects that the mobile device 300 should shift to the idle mode, the throughput estimation unit 120 estimates the throughput of the transitionable band. When the mobile device 300 shifts to the idle mode due to the end of a call or the completion of data communication, the throughput estimation unit 120 can change the mobile device 300 such as the bandwidth provided by the serving base station 201 and the neighboring base stations 202 and 203. The correct bandwidth. Throughput estimating section 120 estimates the throughput indicating the communication capability of the band according to any method for each identified band using the free capacity and / or the different frequency measurement result of each band.

  In one embodiment, the throughput estimation unit 120 may estimate the throughput of each band based on the identified free capacity of each band that can be transitioned and the communication quality of the different frequency measurement value. For example, the throughput estimation unit 120 collects the current available capacity of the transitionable band from the base stations 201, 202, and 203, and uses the different frequency measurement activation unit that has previously measured the different frequency measurement result for the transitionable band. Obtain from 110. When the free capacity of each band and the different frequency measurement result are acquired, the throughput estimation unit 120 determines the throughput of each band based on the acquired free capacity of each band and the different frequency measurement result.

In one embodiment, the throughput estimation unit 120 calculates a cell (E_Tput_Cell) in which throughput is expected, defines the cell divided by the number of users as expected throughput (E_Tput), and distributes the cells to cells having a large E_Tput. You may make it make it. In particular,
E_Tput = E_Tput_Cell / (HS User + 1)
As a result, the throughput is calculated. Here, HS User is the number of users using HS-PDSCH (High Speed-Physical Downlink Shared Channel) of the corresponding cell. E_Tput_Cell may be calculated from the following table using the number of codes (unused code) available in HS-PDSCH and CQI (obtained from EcN0 measured in compressed mode) as variables.

一実施例では、スループット推定部１２０は、遷移可能な帯域の異周波測定値の大きさに基づき異周波測定値を複数のパターンにグループ分けし、パターン毎に異なる算出式を適用して各帯域の通信品質を導出してもよい。一例として、帯域の通信品質を示すＣＱＩ（Ｃｈａｎｎｅｌ Ｑｕａｌｉｔｙ Ｉｎｄｉｃａｔｏｒ）は、
ＣＱＩ＝Ｅｃ／Ｎ０＋１０＊ｌｏｇ_１０｛（α−０．１）／（β−γ＊１０^{ＥｃＮ０／１０}）｝＋１６．６
により算出されてもよい。ここで、Ｅｃ／Ｎ０は異周波測定により測定された受信品質であり、αは総送信電力のうち下りデータチャネル（ＨＳ−ＰＤＳＣＨなど）及び下り制御チャネル（ＨＳ−ＳＣＣＨなど）に割り当てられる送信電力のパーセンテージであり、βは総送信電力のうち共通パイロットチャネル（ＰＣＰＩＣＨなど）に割り当てられる送信電力のパーセンテージを示し、γはＥｃ／Ｎ０を測定した際の共通パイロットチャネル以外の送信電力が総送信電力に占めるパーセンテージを示す。

In one embodiment, the throughput estimation unit 120 groups the different frequency measurement values into a plurality of patterns based on the magnitude of the different frequency measurement values of the transitionable band, and applies a different calculation formula for each pattern to each band. The communication quality may be derived. As an example, CQI (Channel Quality Indicator) indicating the communication quality of the band is:
CQI = Ec / N0 + 10 * log ₁₀ {(α−0.1) / (β−γ * 10 ^{EcN0 / 10} )} + 16.6
May be calculated. Here, Ec / N0 is the reception quality measured by the different frequency measurement, and α is the transmission power allocated to the downlink data channel (HS-PDSCH, etc.) and the downlink control channel (HS-SCCH, etc.) of the total transmission power. Β represents the percentage of the transmission power allocated to the common pilot channel (such as PCPICH) among the total transmission power, and γ represents the transmission power other than the common pilot channel when measuring Ec / N0. Indicates the percentage of

  It is known that the CQI indicating the communication quality of the band varies depending on the BLER (Block Error Rate) depending on the propagation environment and the number of resources at the time of measurement and includes an error. In order to reduce this error, the value of Ec / N0 is divided into three patterns of high quality, medium quality and low quality, and the CQI is calculated by a different method or different calculation formula for each pattern. For example, for low quality patterns, the error due to traffic power is small and the CQI is also small. Therefore, γ = total transmission power−common pilot channel power is set. For medium quality patterns, a fixed CQI is used because an error due to traffic power becomes large. For high quality patterns, the error due to traffic power is large and the CQI is also large, so γ = transmission power of R99CH−common pilot channel power. The grouping into high quality, medium quality, and low quality patterns is performed using any appropriate two reception level thresholds. Based on the CQI of each band calculated in this way and the notified free capacity, the throughput estimation unit 120 may estimate the throughput of each band.

  The standby band determination unit 130 determines a standby band that the mobile device 300 that has shifted to the idle mode should be in based on the stored different frequency measurement value and the estimated throughput. In one embodiment, as illustrated in FIG. 5, the standby bandwidth determination unit 130 includes a standby candidate bandwidth determination unit 131, an excluded bandwidth detection unit 132, and a maximum throughput bandwidth determination unit 133.

  Standby candidate band determining section 131 determines a band that mobile device 300 can transition to as a standby candidate band. For example, the standby candidate band determination unit 131 initially sets a band provided by the serving base station 201 and the neighboring base stations 202 and 203 to which the mobile device 300 can transition as the standby candidate band. When the exclusion band detection unit 132 detects a band to be excluded, the standby candidate band determination unit 131 excludes the detected band from the standby candidate band.

  The excluded band detection unit 132 detects a band to be excluded from the standby candidate bands. In one embodiment, the excluded band detection unit 132 compares the different frequency measurement value of each standby candidate band with a predetermined threshold value, and identifies a band having a different frequency measurement value less than the predetermined threshold as a band to be excluded. To do. When a band to be excluded is detected, the excluded band detection unit 132 notifies the standby candidate band determination unit 131 of the detected band, and the standby candidate band determination unit 131 excludes the band from the standby candidate band. Let Note that the predetermined threshold value may be set to any appropriate communication quality below which communication becomes unstable.

  The maximum throughput bandwidth determination unit 133 determines a bandwidth having the maximum throughput among the standby candidate bandwidths, and notifies the mobile device 300 of the determined standby bandwidth. Specifically, the maximum throughput band determination unit 133 refers to the throughput of each standby candidate band calculated by the throughput estimation unit 120, and determines the band having the maximum throughput as the standby band.

  Next, with reference to FIGS. 6 to 7, a description will be given of bandwidth distribution control processing in the wireless network control device according to one embodiment of the present invention. FIG. 6 is a flowchart showing band dispersion control processing according to an embodiment of the present invention.

  As shown in FIG. 6, in step S101, the radio network controller 100 causes the mobile device 300 to transmit a compressed mode in response to a predetermined trigger such as the communication quality of the serving base station 201 being lower than a predetermined threshold. To move to.

  In step S102, the radio network controller 100 receives and stores the different frequency measurement value from the mobile device 300 that has shifted to the compressed mode.

  In step S103, when the radio network controller 100 detects that the mobile device 300 has finished the call or data communication, the radio network control device 100 determines that the mobile device 300 should shift to the idle mode.

  In step S104, the radio network controller 100 identifies the bands that can be shifted by the mobile device 300, collects the free capacity of each identified band from the base stations 201, 202, and 203, and in step S102, collects the base stations 201, The different frequency measurement values acquired for 202 and 203 are extracted. As will be described in detail with reference to FIG. 7, radio network control apparatus 100 determines the standby band of mobile device 300 based on the acquired free capacity and the different frequency measurement value, and idles together with the determined standby band. The mobile device 300 is notified that it should shift to the mode.

  FIG. 7 is a flowchart showing a standby bandwidth determination process according to an embodiment of the present invention. FIG. 7 is an example of the process in step S105 of FIG.

  As shown in FIG. 7, in step S201, the radio network controller 100 sets a band in which the mobile device 300 can transition as a standby candidate band. Initially, the standby candidate band may be set to the band of the serving base station 201 and the neighboring base stations 202 and 203 of the mobile device 300.

  In step S202, the radio network controller 100 detects a band having a different frequency measurement value less than a predetermined threshold from the standby candidate band. When the band is detected (S202: Y), the flow proceeds to step S203, and in step S203, the radio network controller 100 excludes the detected band from the standby candidate bands. In other words, even if high throughput is expected, the detected bandwidth is not appropriate as the standby bandwidth because the communication quality is not sufficient. On the other hand, when a band having a different frequency measurement value less than the threshold value is not detected (S202: N), the flow proceeds to step S205. In this case, it is determined that any standby candidate band has sufficient communication quality and is appropriate as the standby band.

  In step S204, the radio network controller 100 determines whether there is one remaining standby candidate band. If there is one remaining standby candidate band, the standby candidate band is determined as the standby band, and the flow proceeds to step S206.

  On the other hand, when a plurality of standby candidate bands remain (S204: N), the flow proceeds to step S205, and in step S205, the radio network controller 100 refers to the throughput of each band calculated in step S104. Then, the bandwidth with the maximum throughput is identified from the standby candidate bandwidths. The identified band corresponds to a band having a communication quality equal to or higher than a predetermined threshold and having a maximum throughput among bands that can be shifted by the mobile device 300.

  In step S206, the radio network controller 100 instructs the mobile device 300 to shift to the idle mode and notifies the mobile device 300 of the determined standby bandwidth. When receiving the instruction, the mobile device 300 shifts to the designated standby band and shifts to the idle mode.

  As mentioned above, although the Example of this invention was explained in full detail, this invention is not limited to the specific embodiment mentioned above, In the range of the summary of this invention described in the claim, various deformation | transformation・ Change is possible.

DESCRIPTION OF SYMBOLS 10 Wireless communication system 100 Wireless network control apparatus 110 Different frequency measurement starting part 120 Throughput estimation part 130 Standby band determination part 131 Standby candidate band determination part 132 Exclusion band detection part 133 Maximum throughput band determination part 201,202,203 Base station 300 Mobile

Claims (5)

A different frequency measurement activation unit that shifts the mobile device to a different frequency measurement mode, and acquires and stores a different frequency measurement value indicating communication quality of a transitionable band measured by the mobile device during the activation of the different frequency measurement mode; ,
When it is determined that the mobile device should shift to the idle mode, a throughput estimation unit that estimates the throughput of the transitionable band;
Based on the stored different frequency measurement value and the estimated throughput, a standby band determination unit that determines a standby band in which the mobile device that has shifted to the idle mode should be located;
A wireless network control device comprising :
The throughput estimation unit obtains a free capacity of the transitionable band and groups the different frequency measurement values into a plurality of patterns based on a reception level indicating the different frequency measurement value of the transitionable band. The communication quality of the different frequency measurement value of the transitionable band is derived by applying a different calculation formula for each pattern, and the transition is possible based on the acquired free capacity and / or the derived communication quality. A wireless network control device that estimates bandwidth throughput . The throughput estimation unit is configured when the mobile station transits to the idle mode, the that Tokusu preparative space of possible transition band, the radio network control device according to claim 1. The standby bandwidth determination unit
A standby candidate band determining unit that determines a band in which the mobile device can transition as a standby candidate band;
An exclusion band detector for detecting a band to be excluded from the standby candidate bands;
A maximum throughput bandwidth determination unit for determining a bandwidth having a maximum throughput among the standby candidate bandwidths;
And the maximum throughput band determination unit determines a band having the maximum throughput among the standby candidate bands acquired by excluding the band detected by the exclusion band detection unit as a standby band of the mobile device. The radio network controller according to claim 1 or 2 , wherein the mobile network device is notified of the determined standby bandwidth to the mobile device. The excluded band detection unit compares the different frequency measurement value of the standby candidate band with a predetermined threshold, detects a band having a different frequency measurement value less than the predetermined threshold as the band to be excluded,
The radio network controller according to claim 3 , wherein the standby candidate band determination unit excludes the detected band from the standby candidate band. A bandwidth distribution control method in a wireless network control device, comprising:
Transitioning the mobile unit to a different frequency measurement mode;
Obtaining and storing a different frequency measurement value indicating communication quality of a transitionable band measured by the mobile device during activation of the different frequency measurement mode;
Determining that the mobile device should transition to idle mode, estimating a throughput of the transitionable band; and
Based on the stored different frequency measurement value and the estimated throughput, determining a standby band in which the mobile device that has shifted to the idle mode should be located;
Notifying the mobile device of the determined standby bandwidth;
I have a,
The step of estimating the throughput acquires the free capacity of the transitionable band, and converts the different frequency measurement values into a plurality of patterns based on a reception level indicating the different frequency measurement values of the transitionable band. Grouping and applying different calculation formulas for each pattern to derive the communication quality of the different frequency measurement value of the transitionable band, and based on the acquired free capacity and / or the derived communication quality, the transition A bandwidth distribution control method for estimating the throughput of a possible bandwidth .

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