Base transceiver station and channel rate control method

The present invention relates to a radio base station apparatus and a transmission line rate control method used in a radio communication system using an HSDPA (High Speed Downlink Packet Access) communication method.

Conventionally, in a wireless communication system including a wireless base station device, one using the HSDPA communication method is known. A wireless communication system using this HSDPA communication method is a wireless access consisting of a wireless network controller (RNC: Radio Network Controller) and a wireless base station device (BTS: Base Transceiver Station) located below the wireless network controller. It consists of a network and a mobile terminal device (UE: User Equipment) connected to the wireless access network, and improves wireless utilization efficiency and high-speed transmission by varying the throughput according to the wireless environment of the mobile terminal device and the number of connected terminals. It has been realized.

Further, in the wireless communication system using this HSDPA communication method, the throughput varies depending on the wireless environment of the mobile terminal device and the number of connected terminals, so that the transmission speed between the wireless network control device and the wireless base station device is wireless. When it is faster than the transmission speed of the section, the amount of data retained in the wireless base station device increases, and when the transmission speed between the wireless network control device and the wireless base station device is slower than the transmission speed of the wireless section. Has a problem that the utilization efficiency of the radio section is lowered. In order to solve this problem, in a wireless communication system using the HSDPA communication method, flow control is performed between the wireless network control device and the wireless base station device according to the transmission speed of the wireless section.

Specifically, the wireless base station device calculates the transmission quality based on the amount of data loss such as data destruction, omission, and disposal with the wireless network device, and the wireless environment of the mobile terminal device and the number of connected terminals. The radio quality is calculated based on the throughput assumed by the above and the amount of buffer retention in the radio base station equipment, and the allowable amount of data transmitted from the radio network device to the radio base station is calculated from this transmission line quality and radio quality. By notifying the wireless network control device of this permissible amount of data, the amount of data transmitted from the wireless network device is controlled.<patcit num="1"><text>Japanese Unexamined Patent Publication No. 2008-053851</text></patcit>

<p> However, in the above-mentioned wireless communication system, when a data amount exceeding the processing capacity of the wireless base station apparatus is transmitted from the wireless network control apparatus to the wireless base station apparatus, the wireless base station apparatus has only a receiving function. There was a possibility that other functions such as call processing control and monitoring control would also malfunction. In particular, a small wireless base station device for indoor use is designed to have a low processing capacity, so that there is a possibility of malfunction.</p><p> The present invention has been made in view of this point, and an object of the present invention is to provide a wireless base station apparatus and a transmission line rate control method capable of performing stable processing in a wireless communication system compatible with the HSDPA communication system.</p>

<p> The wireless base station device of the present invention is a wireless base station device that supports high-speed downlink packet access, and is a wireless quality calculation means for obtaining wireless quality between a wireless access network and a mobile terminal device, and a wireless network control device. Allowable data using the transmission line quality calculating means for obtaining the transmission line quality between the two, the CPU usage rate measuring means for measuring the CPU usage rate of the own device, and the wireless quality, the transmission line quality, and the CPU usage rate. Allowable data amount calculation means to calculate the amount,<u style="single">The permissible data amount calculation means calculates the permissible data amount by correcting the permissible data amount obtained by the radio quality and the transmission line quality with a correction value based on the CPU usage rate.</u>It is characterized by that.</p><p> The transmission line rate control method of the present invention includes a step of obtaining wireless quality between a wireless access network and a mobile terminal device in a wireless base station device corresponding to high-speed downlink packet access, and wireless in the wireless base station device. The step of obtaining the transmission line quality with the network control device, the step of measuring the CPU usage rate in the wireless base station device, and the wireless quality, the transmission line quality, and the CPU usage in the wireless base station device. A process of calculating the allowable data amount from the rate, a step of sending the allowable data amount to the wireless network control device, and a transmission line between the wireless network control device and the wireless base station device based on the allowable data amount. Equipped with a process to control the rate<u style="single">However, the permissible data amount is a correction permissible data amount obtained by correcting the permissible data amount obtained by the radio quality and the transmission line quality with a correction value based on the CPU usage rate.</u>It is characterized by that.</p><p> According to this configuration, since the CPU usage rate is included in the calculation condition of the allowable data amount, the allowable data amount is calculated in consideration of the processing capacity of the wireless base station apparatus. Therefore, since the wireless network control device does not transmit data exceeding the processing capacity of the wireless base station device, the wireless base station device can perform stable processing.</p><p> According to this configuration, the allowable data amount obtained for the radio quality and the transmission line quality can be corrected by the correction value based on the CPU usage rate.</p><p> Further, the present invention is characterized in that, in the radio base station apparatus, the correction value is an allowable data amount reduction amount corresponding to at least one CPU usage rate threshold value and / or at least one correction release threshold value.</p><p> Further, the present invention is characterized in that, in the transmission line rate control method, the correction value is changed corresponding to at least one CPU usage rate threshold value and / or at least one correction release threshold value.</p><p> According to this configuration, the correction value can be changed with a simple control configuration. In addition, when a plurality of CPU usage rate threshold values and a plurality of correction release threshold values are provided, the correction value can be changed step by step, and a more appropriate allowable data amount can be obtained in response to a change in the CPU usage rate. Can be calculated.</p><p> Further, the present invention is characterized in that, in the radio base station apparatus, the permissible data amount calculation means cancels the correction of the permissible data amount by using the correction cancellation threshold value.</p><p> Further, the present invention is characterized in that, in the transmission line rate control method, the correction of the allowable data amount is canceled by using the correction cancellation threshold value.</p><p> According to this configuration, when the CPU usage rate falls below the correction cancellation threshold value, the correction of the allowable data amount can be canceled.</p><p> Further, the present invention is characterized in that, in the wireless base station apparatus, the wireless base station apparatus is a small wireless base station apparatus having a carrier number of 1 or less and a maximum simultaneous connection number of 4 or less.</p><p> According to this configuration, a wireless communication system can be constructed at low cost by adopting a small wireless base station apparatus.</p>

<p> According to the present invention, stable processing can be executed in a wireless communication system compatible with the HSDPA communication method.</p>

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a block diagram of a wireless communication system.

As shown in FIG. 1, the wireless communication system 1 is wirelessly connected to a wireless access network 2 and a wireless access network 2 including a wireless network control device 4 and a wireless base station device 5 wiredly connected to the wireless network control device 4. It is composed of the mobile terminal device 6 and the mobile terminal device 6. Further, in the wireless communication system 1, the HSDPA communication method is used, and the wireless network control device 4 and the wireless base station device 5 are adjusted according to the fluctuation of the throughput according to the wireless environment of the mobile terminal device 6 and the number of connected terminals. Flow control is performed between and.

The wireless network control device 4 monitors the wireless line between the mobile terminal device 6 and the wireless base station device 5, and also performs wireless control such as allocating a wireless channel between the mobile terminal device 6 and the mobile terminal device 6. .. The wireless network control device 4 provides the HSDPA service to the mobile terminal device 6 by allocating a high speed downlink shared channel (HS-DSCH) as a wireless channel.

The wireless base station device 5 is a small wireless base station device having a carrier number of 1 or less and a maximum simultaneous connection number of 4 or less, and the data received from the wireless network control device 4 is used as a wireless radio wave in the mobile terminal device 6. I'm sending. Further, the wireless base station device 5 has the radio quality between the wireless access network 2 and the mobile terminal device 6, the transmission path quality between the wireless network control device 4 and the wireless base station device 5, and the processing capacity of the wireless base station device 5. The allowable data amount is calculated based on the allowable data amount, and the allowable data amount is included in the allowable data amount control signal (CA: Capacity Allocation) and notified to the wireless network control device 4, so that the amount of data transmitted from the wireless network control device 4 can be determined. I'm in control.

That is, in the wireless communication system 1, the amount of data transmitted from the wireless network control device 4 is controlled in consideration of the transmission quality from the wireless network control device 4 to the mobile terminal device 6. Hereinafter, the details of the radio base station apparatus will be described with reference to FIG. FIG. 2 is a control block diagram of a radio base station.

As shown in FIG. 2, the wireless base station device 5 is located between the FP transmission / reception function unit 11 which is an interface between the wireless network control device 4 and the mobile terminal device 6 and the wireless network control device 4 and the wireless base station device 5. It is configured to include a flow control function unit 12 that controls the flow in the above. Further, the flow control function unit 12 includes a CA calculation unit 14, a Ui rate calculation unit 15, a Uu rate calculation unit 16, and a CPU usage rate measurement function unit 17.

The FP transmission / reception function unit 11 communicates with the wireless network control device 4 by the HS-DSCH frame protocol, performs reception processing of transmission data from the wireless network control device 4, and data output from the flow control function unit 12. Is converted to FP and transmitted to the wireless network control device 4.

The Ui rate calculation unit 15 measures data corruption, omission, destruction, etc. in Iub (Interface between an RNC and a Node B), which is an interface between the wireless network control device 4 and the wireless base station device 5, and Iub. The transmission line quality (hereinafter referred to as Ui rate) is calculated.

Specifically, the Ui rate calculation unit 15 monitors the sequence number and checksum included in the transmission data from the wireless network control device 4 when congestion occurs in the Iub, and whether or not the sequence numbers are continuous, and whether or not the sequence numbers are continuous. The Ui rate of Iub is calculated by measuring data corruption, omission, destruction, etc. in Iub depending on whether the checksums match. The Ui rate calculation unit 15 outputs the calculated Ui rate to the CA calculation unit 14.

The Uu rate calculation unit 16 calculates the buffer retention data sweep time, which is the time that the transmission data from the wireless network control device 4 stays in the buffer of the wireless base station device 5 until it is sent to the mobile terminal device 6. Calculate the radio quality (hereinafter referred to as Uu rate) in the radio section.

Specifically, the Uu rate calculation unit 16 monitors the estimated throughput estimated by the radio wave reception state of the mobile terminal device 6 and the number of connected terminals, and addresses this estimated throughput and the mobile terminal device 6 staying in the buffer. The Uu rate is calculated by calculating the buffer retention data sweep time from the amount of data. The Uu rate calculation unit 16 outputs the calculated Uu rate to the CA calculation unit 14.

The CPU usage rate measurement function unit 17 measures the CPU usage rate of the wireless base station device 5, and outputs the measured CPU usage rate to the CA calculation unit 14.

The CA calculation unit 14 allows the wireless base station device 5 to receive allowable data from the wireless network control device 4 based on the Ui rate output by the Ui rate calculation unit 15 and the Uu rate output by the Uu rate calculation unit 16. Calculate the amount. Further, the CA calculation unit 14 corrects the calculated allowable data amount according to the CPU usage rate output from the CPU usage rate measurement function unit 17.

Specifically, the radio base station apparatus 5 has an allowable data amount correction table showing the relationship between the threshold value and the correction amount as shown in FIG. 3, and the allowable data amount is corrected by the allowable data amount correction table. There is. This permissible data amount correction table is set in association with the CPU usage rate threshold value, the correction release threshold value, and the CA rate reduction amount (allowable data amount reduction amount) for each threshold value. The CPU usage threshold is the CPU usage threshold that starts the correction of the allowable data amount, the correction release threshold is the CPU usage threshold that ends the correction of the allowable data amount, and the CA rate reduction amount is the correction amount of the allowable data amount. Shown.

For example, when threshold # 1 and threshold # 2 are set in the wireless base station device 5, if the CPU usage rate output from the CPU usage rate measurement function unit 17 exceeds 60%, the allowable data amount is 100. It is corrected to be [kbps] lower, and when the CPU usage exceeds 80%, the allowable data amount is corrected to be 200 [kbps] lower. In addition, when the CPU usage rate output from the CPU usage rate measurement function unit 17 falls below 60%, the correction amount of the allowable data amount drops from 200 [kbps] to 100 [kbps], and the CPU usage rate drops to 40%. If it falls below the limit, the correction of the allowable data amount is canceled.

Further, when the CA calculation unit 14 calculates the allowable data amount, the CA calculation unit 14 includes the allowable data amount in the allowable data amount control signal and outputs it to the FP transmission / reception function unit 11. The permissible data amount control signal is converted into FP by the FP transmission / reception function unit 11 and transmitted to the wireless network control device 4, and the transmission data amount of the wireless network control device 4 is controlled. In this way, the CA calculation unit 14 calculates the allowable data amount in consideration of not only the Ui rate and the Uu rate but also the CPU usage rate.

Next, the relationship between CPU usage and throughput will be described with reference to FIGS. 4 (a) and 4 (b). FIG. 4A shows the CPU usage rate and throughput of the conventional wireless base station device that does not include the CPU usage rate in the calculation conditions of the CPU usage rate, throughput, and allowable data amount of the wireless base station device according to the present embodiment. 4 (b) is an allowable data amount correction table of the radio base station apparatus according to the present embodiment. In FIG. 4A, the curve graph of the solid line W1 is the CPU usage rate of the wireless base station device according to the present embodiment, and the curve graph of the broken line W2 is the CPU usage rate of the conventional wireless base station device and the solid line B1. The columnar graph shows the throughput of the wireless base station apparatus according to the present embodiment, and the columnar graph of the broken line B2 shows the throughput of the conventional wireless base station apparatus.

As shown in FIG. 4A, in the conventional wireless base station device, the CPU usage rate is not included in the calculation condition of the allowable data amount, and the allowable data amount is calculated based on the Ui rate and the Uu rate. When transmitted from the wireless network control device 4 with a transmission data amount exceeding the processing capacity of the conventional wireless base station device, the CPU usage rate of the conventional wireless base station device exceeds 100% as shown in time Ta1 and Ta2. It was closed. For this reason, the operation of the conventional wireless base station apparatus becomes unstable, and there is a possibility that not only the reception function but also other functions such as call processing control and monitoring control may malfunction.

However, in the radio base station apparatus 5 according to the present embodiment, the CPU usage rate is included in the calculation condition of the allowable data amount, and the allowable data amount calculated based on the Ui rate and the Uu rate is based on the CPU usage rate. The CPU usage rate of the wireless base station device 5 is suppressed to 100% or less. In this case, the radio base station apparatus 5 has thresholds # 1 and thresholds # 2 set in the allowable data amount correction table shown in FIG. 4 (b), and the CPU usage threshold of threshold # 1 is 60%. The correction cancellation threshold is 40%, the CA rate reduction is 100 [kbps], the CPU usage threshold of threshold # 2 is 80%, the correction cancellation threshold is 60%, and the CA rate reduction is 200 [kbps].

Then, in the time Tb1 from when the CPU usage rate shown in the solid line W1 exceeds 60% to when it exceeds 80%, the allowable data amount is corrected so as to decrease by 100 [kbps], so that the throughput is compared with the conventional example. Then, the throughput decreases by 100 [kbps], and the throughput is corrected so that the allowable data amount decreases by 200 [kbps] in Tb2, which is the time from when the CPU usage exceeds 80% to when it falls below 60%. It is 200 [kbps] lower than that. Furthermore, in the time Tb3 from when the CPU usage falls below 60% to when it exceeds 80% again, the throughput drops by 100 [kbps] compared to the conventional example, and 60 after the CPU usage exceeds 80% again. Time to fall below% At Tb4, the throughput is reduced by 100 [kbps] compared to the conventional example.

By correcting the permissible amount of data according to the CPU usage rate in this way, the throughput of the wireless base station device 5 decreases, so that the CPU usage rate is suppressed to 100% or less, and the wireless base station device 5 The operation is stable. In the present embodiment, the threshold value # 1 and the threshold value # 2 are set in the allowable data amount correction table, but any number of threshold values may be set. Further, although the CPU usage rate threshold value and the correction release threshold value are associated with the CA rate decrease amount, either one of the CPU usage rate threshold value and the correction release threshold value may be associated with the CA rate decrease amount.

Next, the allowable data amount calculation process of the wireless base station apparatus will be described. FIG. 5 is a flowchart of the allowable data amount calculation process of the wireless base station apparatus. In this flowchart, for convenience of explanation, only the CPU usage rate threshold and the CA rate decrease amount are associated with the allowable data amount correction table of the wireless base station device, and the allowable data amount when the CPU usage rate threshold is exceeded. Shall be corrected.

First, the Uu rate calculation unit 16 calculates the Uu rate from the assumed throughput for the mobile terminal device 6 and the amount of data accumulated in the buffer (step S1). Next, when the Uu rate is calculated by the Uu rate calculation unit 16, the Ui rate calculation unit 15 measures the data corruption, omission, and destruction in Iub, and calculates the Ui rate (step S2).

Next, the Uu rate and the Ui rate calculated by the Uu rate calculation unit 16 and the Ui rate calculation unit 15 are input to the CA calculation unit 14, and the radio base station device 5 receives from the wireless network control device 4 by the CA calculation unit 14. The possible permissible amount of data is calculated (step S3). Next, when the allowable data amount is calculated by the CA calculation unit 14, the CPU usage rate of the wireless base station device 5 is calculated by the CPU usage rate measurement function unit 17 (step S4).

Next, the CPU usage rate calculated by the CPU usage rate measurement function unit 17 is input to the CA calculation unit 14, and the CA calculation unit 14 reads the CPU usage rate threshold value from the allowable data amount correction table, and the CPU usage rate is calculated. Whether or not it is equal to or higher than the CPU usage threshold is determined (step S5).

When the CA calculation unit 14 determines that the CPU usage rate is equal to or higher than the CPU usage rate threshold value (step S5: Yes), the CA rate reduction amount is read from the allowable data amount correction table, and the allowable data amount is the CPU. It is corrected according to the usage rate (step S6). Then, the CA calculation unit 14 includes the corrected allowable data amount in the allowable data amount control signal and outputs it to the FP transmission / reception function unit 11, and the FP transmission / reception function unit 11 converts the allowable data amount control signal into FP and converts it into a wireless network. Sent to controller 4 (step S8) .

On the other hand, when the CA calculation unit 14 determines that the CPU usage rate is smaller than the CPU usage rate threshold (step S5: No), the permissible data amount control signal is not corrected (step S7). It is included in the FP transmission / reception function unit 11 and is output to the FP transmission / reception function unit 11, and the allowable data amount control signal is converted into an FP in the FP transmission / reception function unit 11 and transmitted to the wireless network control device 4 (step S8).

Then, when the wireless network control device 4 receives the allowable data amount control signal, the wireless network control device 4 controls the amount of transmitted data to the wireless base station device 5 based on the allowable data amount included in the allowable data amount control signal. This prevents transmission of data in an amount larger than the processing capacity of the radio base station device 5.

As described above, according to the wireless base station apparatus 5 according to the present embodiment, the CPU usage rate is included in the calculation condition of the allowable data amount, so that the allowable data amount is taken into consideration in consideration of the processing capacity of the wireless base station apparatus 5. Is calculated. Therefore, since the wireless network control device 4 does not transmit data in an amount larger than the processing capacity of the wireless base station device 5, the wireless base station device 5 can perform stable processing.

In the present embodiment, the wireless base station apparatus 5 has been described by exemplifying a small wireless base station apparatus having a carrier number of 1 or less and a maximum simultaneous connection number of 4 or less, but the configuration is limited to this configuration. is not it. For example, the present invention may be applied to a large-scale radio base station device installed outdoors.

Moreover, the embodiment disclosed this time is an example in all respects and is not limited to this embodiment. The scope of the present invention is shown not only by the above-described embodiment but also by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

As described above, the present invention has the effect of being able to execute stable processing in a wireless communication system compatible with the HSDPA communication method, and particularly has a low processing capacity, a small size, and an inexpensive wireless base station apparatus and transmission line rate control. Useful for the method.

<figref num="1">It is a figure which shows the embodiment of the wireless base station apparatus which concerns on this invention, and is the block diagram of the wireless communication system.</figref><figref num="2">It is a figure which shows the embodiment of the wireless base station apparatus which concerns on this invention, and is the control block diagram of a wireless base station.</figref><figref num="3">It is a figure which shows the embodiment of the radio base station apparatus which concerns on this invention, and is the figure which shows an example of the permissible data amount correction table.</figref><figref num="4">It is a figure which shows the embodiment of the wireless base station apparatus which concerns on this invention, (a) is the conventional wireless base which does not include the CPU usage rate in the calculation condition of the CPU usage rate and the throughput and the permissible data amount of the wireless base station apparatus. A graph comparing the CPU usage rate and throughput of a station device, (b) is a diagram showing an example of an allowable data amount correction table.</figref><figref num="5">It is a figure which shows the embodiment of the wireless base station apparatus which concerns on this invention, and is the flowchart of the permissible data amount calculation processing of a wireless base station apparatus.</figref>

Code description

1 Wireless communication system 2 Radio access network 4 Wireless network controller 5 Radio base station equipment 6 Mobile terminal device 11 FP transmission / reception function unit 12 Flow control function unit 14 CA calculation unit (allowable data amount calculation means) 15 Ui rate calculation unit (transmission line quality calculation means) 16 Uu rate calculation unit (wireless quality calculation means) 17 CPU usage rate measurement function unit (CPU usage rate measurement means)