KR20070090446A - Method and apparatus for deciding credit using channel quality indicator in a mobile communication system - Google Patents

Abstract

A method and an apparatus for determining a credit by using a CQI(Channel Quality Indicator) in a mobile communication system are provided to optimally maintain the buffer capacity of a node B by calculating a new credit, which indicates the amount of data to be requested from an RNC(Radio Network Controller), by using the communication state between UE(User Equipment) and the node and the remaining buffer capacity of the node B. A node B receives a CQI from UE, checks its own idle buffer capacity in accordance with call setup, and calculates a buffer-based credit(300-310). Then, the node B compares the received CQI with the first threshold(315). If the CQI is smaller than the first threshold, the node B increases a buffer-based credit reduction rate 'alpha' by an appointed value(315,320). In case the CQI is larger than the first threshold, however, the node B decreases 'alpha' by an appointed value(325,330). The node B calculates a new credit, based on the increased or decreased rate 'alpha' and the calculated buffer-based credit(335). Then, the node B transmits the calculated new credit to an RNC through a capacity allocation message(345).

Description

Method and apparatus for determining credit using channel quality indication in mobile communication system {method and apparatus for deciding credit using Channel Quality Indicator in a mobile communication system}

1 is a timing diagram showing a credit calculation based on a buffer capacity according to the prior art.

2 is a timing diagram showing credit calculation using channel quality indication according to a preferred embodiment of the present invention.

3 is a flowchart for calculating a new credit in a mobile communication network according to a preferred embodiment of the present invention.

4 is a block diagram of a base station for calculating a new credit according to a preferred embodiment of the present invention.

5 is a block diagram of a mobile communication system according to a preferred embodiment of the present invention.

The present invention relates to a mobile communication system, and in particular, provides a method and apparatus for transmitting a new credit to a wireless network controller after calculating a new credit using a channel quality indication.

High Speed Downlink Packet Access (hereinafter referred to as HSDPA) based communication network is a 3.5 generation communication network that transmits data in downlink channel in 3rd generation Wideband Code Division Multiple Access (WCDMA). It is a form that has been improved by improving ability.

In providing a multimedia service, unlike the WCDMA supporting a maximum of 2 Mbps (mega bit per second), the HSDPA may support a maximum of 14 Mbps depending on the communication state between the base station and the repeater. This high speed can be supported by a packet dedicated channel called a High Speed Downlink Shared Channel (HS-DSCH) and a base station instead of a Radio Network Controller (hereinafter referred to as RNC). This is because the packet data scheduling function is in charge.

In the HSDPA, the RNC requests credit information indicating the number of packet data to be transmitted in downlink to the base station while transmitting packet data to the base station, or the base station can transmit the credit information to the RNC at any time, and the base station buffers Credit calculated based on the capacity is sent to the RNC. The RNC then provides the downlink data to the base station based on the credit.

1 is a timing diagram illustrating a credit calculation based on a buffer capacity according to the prior art. When the RNC 110 transmits a capacity request message (hereinafter referred to as CAPACITY REQUEST) to the base station 100, the base station 100 buffer capacity. Calculate 130 based on the credit. Credit calculated based on the buffer capacity is carried in the capacity allocation message (hereinafter referred to as CAPACITY ALLOCATION) 140 is transmitted to the RNC 110, the RNC 110 is based on the buffer-based credit based on the base station ( 100 transmit packet data. The CAPACITY ALLOCATION may be transmitted to the RNC 110 at any time or when the CAPACITY REQUEST is received at the base station 100.

When the communication state between the user equipment (hereinafter referred to as UE) and the base station is good, the above operation is normally performed. However, if the communication state is not good and the packet data transmitted from the base station to the UE is delayed, the amount of packet data that the base station can receive is inevitably reduced, but due to buffer-based credit, the RNC continues to transmit the packet data to the base station. The transmission causes an overload on the buffer of the base station, resulting in inconvenience in communication.

The present invention devised to solve this problem relates to a mobile communication system, and in particular, provides a method and apparatus for transmitting a new credit to a wireless network controller after calculating a new credit using a channel quality indication.

According to a preferred embodiment of the present invention, in a method for obtaining a new credit for overload protection of a buffer in a base station in a mobile communication system,

Receiving a channel quality indication (CQI) according to a communication state between a terminal and a base station;

Calculating a buffer-based credit according to the idle buffer capacity of the base station;

Determining, by the channel quality indication, α;

Calculating a new credit representing the amount of data requested by the radio network controller by subtracting the ratio by the α from the buffer-based credit;

And transmitting the new credit to the radio network controller.

Apparatus of the present invention is a device for obtaining a new credit for overload protection of the buffer in the base station in a mobile communication system,

A channel quality indication (CQI) receiver for receiving a channel quality indication (CQI),

A wireless network controller interface for receiving a capacity request message from the wireless network controller;

A credit calculator for receiving the capacity request message and calculating a new credit using an idle buffer capacity and a channel quality indication (CQI);

And a radio frequency scheduler for instructing the channel quality indicating receiver and the HS-DSCH buffer to operate according to a schedule.

The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that those skilled in the art may better understand the detailed description of the invention that follows.

Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. Those skilled in the art should recognize that the disclosed concepts and specific embodiments of the invention may be readily used as a basis for modifying or designing other structures for achieving the same purposes of the present invention. Those skilled in the art should also recognize that structures equivalent to the invention do not depart from the spirit and scope of the broadest form of the invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, detailed descriptions of well-known functions and configurations that may obscure the gist of the present invention will be omitted.

The main point of the present invention is that the base station calculates a new credit using the channel quality indication received from the terminal as well as its buffer capacity, and transmits the new credit to the wireless network controller so that packet data is transmitted to the base station according to the communication state. To be transmitted.

Although a communication network based on High Speed Downlink Packet Access (hereinafter referred to as HSDPA) is composed of a large number of network elements (NEs), a minimum required radio network controller (hereinafter referred to as RNC) is referred to as RNC. ) And only a base station and a user equipment (hereinafter referred to as UE).

2 is a timing diagram illustrating credit calculation using a channel quality indication according to a preferred embodiment of the present invention.

With a Channel Quality Indicator (hereinafter referred to as CQI) 230 transmitted from the UE 200, the base station 210 may determine a communication state with the UE 200, and the RNC 220 may determine the communication state. When a capacity request message (hereinafter referred to as CAPACITY REQUEST) 240 is transmitted to 210, the base station 210 calculates 250 a new credit using the CQI 230. The new credit is calculated in consideration of the CQI 230 indicating the communication status between the UE 200 and the base station 210 as well as the buffer capacity of the base station 210, and according to the CQI 230 in the buffer-based credit It is calculated by subtracting by the reduction rate α of the buffer-based credit to be determined. The new credit is sent in the capacity allocation message 260 from the base station 210 to the RNC 220.

In this case, the CAPACITY ALLOCATION may be transmitted to the RNC 220 at any time or when the CAPACITY REQUEST is received at the base station 210.

That is, the new credit is calculated by the formula = [buffer-based credit-buffer-based credit * α].

3 is a flowchart for calculating a new credit in a mobile communication network according to a preferred embodiment of the present invention.

In step 300, the base station receives a channel quality indication (CQI) from a user equipment (hereinafter referred to as a UE), and in step 305, checks the buffer capacity of the base station according to the call setup. Calculate buffer-based credits based on buffer capacity. Here, the buffer capacity of the base station refers to the idle buffer capacity of the base station, and the buffer-based credit refers to the number of packet data to be received from the RNC in consideration of the idle buffer capacity.

In step 315, the CQI is compared to be smaller than a predetermined first threshold value, and if it is smaller, the flow proceeds to step 320 to increase α by a predetermined value from the previous α value. In addition, if the CQI is not smaller than the first threshold value, the method proceeds to step 325 to compare whether the CQI is larger than the second threshold value. Decrease by value On the other hand, if the CQI is not greater than the second threshold, the process proceeds to step 340 and the current communication state is good, so that the buffer-based credit is determined to be equal to the new credit (hereinafter referred to as CAPACITY ALLOCATION). Wherein the second threshold has a value not less than the predetermined first threshold.

In step (335), using the formula of [buffer-based credit-buffer-based credit * α] according to the α added or subtracted in the step (330) or the step (330) and the buffer-based credit calculated in the step (310). Calculate the new credit.

In step 345, the base station includes the new credit information in the CAPACITY ALLOCATION message and transmits it to the RNC.

As such, the base station adjusts such that the new credit is not greater than the buffer-based credit.

4 is a block diagram of a base station for calculating a new credit according to a preferred embodiment of the present invention.

The base station 410 serves as a bridge that connects the UE 400 and the RNC 480, and various devices are built in the base station 410 to perform this role, but only essential elements of the present invention will be described herein. do.

A channel quality indication (CQI) receiver 440 receives the CQI from the UE 400 and delivers the CQI to a radio frequency scheduler 430. The RNC 480 transmits packet data to be transmitted through the High Speed Downlink Shared Channel (hereinafter referred to as HS-DSCH) to the HS-DSCH buffer 450 and receives credits through the RNC interface 470. Send a capacity request message requesting information. The capacity request message is transmitted to the credit calculator 460, which calculates the buffer capacity read from the HS-DSCH buffer 450 and the CQI provided from the channel quality indication (CQI) receiver 440. The new credit is calculated as shown in FIG. 3.

The new credit is transmitted to the RNC 480 in a capacity allocation message via the RNC interface 470, and the RNC 480 transfers the amount of packet data to the HS-DSCH buffer 450 based on this. By adjusting, the capacity of the HS-DSCH buffer 450 is not exceeded. The packet data read from the HS-DSCH buffer 450 is transmitted to the UE 400 through the HS-DSCH by the HS-DSCH transmitter 420 under the control of the RF scheduler 430.

The new credit may be calculated based on the CQI received from the UE 400 at the present time or at any time when credit information is requested by the RNC 480 or otherwise.

5 is a block diagram of a mobile communication system according to a preferred embodiment of the present invention. In view of the overall flow, the base station 510 receives the CQI (1), CQI (2)... Channel quality indications of the respective terminals from the plurality of terminals 520, 530, 540 in the area. Receive CQI (n) periodically. Upon receiving the CAPACITY REQUEST message from the RNC 500, the base station 510 receives CQI (1), CQI (2)... The new credits for the terminals 520, 530, and 540 are calculated using CQI (n) and its buffer capacity and transmitted to the RNC 500 through a CAPACITY ALLOCATION message.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. As an example of the modification, only the example using the base station has been described. However, the present invention can be easily applied to a base station apparatus for transmitting and receiving packet data using a terminal or a buffer that provides a CQI without significant modification.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by those equivalent to the scope of the claims.

The present invention is characterized in that the base station calculates a new credit and transmits the new credit to the radio network controller using the channel quality indication received from the terminal, and transmits packet data so that the radio network controller does not exceed the buffer capacity of the base station.

In the present invention, by using the communication status of the terminal and the base station and the remaining buffer capacity of the base station, by calculating a new credit indicating the amount of data to be requested to the RNC, the buffer capacity of the base station can be always maintained properly. There is an advantage.

Claims (7)

In the method for obtaining a new credit for preventing overload of the buffer in the base station in the mobile communication system, Receiving a channel quality indication (CQI) according to a communication state between a terminal and a base station; Calculating a buffer-based credit according to the idle buffer capacity of the base station; Determining a reduction ratio of the buffer-based credit according to the channel quality indication; Calculating a new credit indicating the amount of data requested by the radio network controller by subtracting the reduction ratio from the buffer-based credit; And transmitting the new credit to the wireless network controller. The method of claim 1, wherein the determining of the reduction ratio comprises: If the channel quality indication is less than a predetermined first threshold value, the reduction ratio is increased by a predetermined value compared to a previous value, And if the channel quality indication is greater than a second threshold value that is not less than the first threshold value, reduce the reduction ratio by a predetermined value from a previous value. 3. The credit according to claim 2, further comprising: setting the new credit equal to the buffer-based credit if the channel quality indication is greater than the first threshold and less than the second threshold. Calculation method. In the device for obtaining a new credit for preventing overload of the buffer in the base station in the mobile communication system, A channel quality indication (CQI) receiver for receiving a channel quality indication (CQI), A buffer for storing the packet data provided from the radio network controller until transmission to the terminal; A credit calculator for calculating a new credit using at least one of an idle buffer capacity of the buffer and the channel quality indication (CQI); A wireless network controller interface for transmitting the new credit to the wireless network controller by putting the new credit in a capacity request message; A radio frequency scheduler for scheduling transmission of packet data stored in the buffer according to the CQI; And a transmitter for transmitting the packet data stored in the buffer to the terminal according to the scheduling result. The method of claim 4, wherein the credit calculator, And calculating the new credit by subtracting the reduction ratio of the buffer-based credit according to the channel quality indication from the buffer-based credit. The method of claim 5, wherein the credit calculator, If the channel quality indication is less than a predetermined first threshold value, the reduction ratio is increased by a predetermined value compared to a previous value, And if the channel quality indication is greater than a second threshold value not smaller than the first threshold value, reduce the reduction rate by a predetermined value from a previous value. 7. The credit according to claim 6, wherein the credit calculator sets the new credit equal to the buffer-based credit if the channel quality indication is greater than the first threshold and less than the second threshold. Computing device.

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