KR100938096B1 - Method and apparatus for managing buffer in communication system - Google Patents

Abstract

The present invention provides a method for managing a buffer of a base station in a communication system, the method comprising: setting a threshold value for each service class for scheduling packet input / output of the buffer according to a priority of a service class, and transmitting a packet to the buffer. If received, estimating and storing the available space size of the buffer after receiving the packet, comparing the first threshold value corresponding to the first service class which is a service class of the packet with the estimated available space size of the buffer. Scheduling packet input and output of the buffer; Through buffer management based on priority of service class, it is possible to protect service of high priority packet from low priority packet, and threshold to decide service interruption and resumption determined by service class based on buffer size change value. If there is a slight difference from the value, a hysteresis interval or timer can be defined to prevent unnecessary repetition of switching between service interruption and resumption points, and a message indicating when the service is suspended or resumed, While the message is retransmitted according to whether or not a confirmation message is received, there is an effect of reducing a lost signal.

WIMAX, Buffer Management, Quality of Service

Description

Method and device for managing buffers in communication systems {THE METHOD AND APPARATUS FOR MANAGING BUFFER IN A COMMUNICAITON SYSTEM}

The present invention relates to a method and apparatus for managing a buffer according to a service priority in a communication system.

Hereinafter, the present invention will be described as a broadband wireless access (Wideband Wireless Access) system based on IEEE 802.16 WMAN (Wireless Metropolitan Area Networks) as an example of a communication system.

Broadband wireless access system, also called mobile WiMAX system, can provide various multimedia services such as voice service, internet access service, high-speed data service, and video service wirelessly anytime and anywhere through mobile terminal through mobile terminal. have. In addition, a high-speed data service is possible and a service fee is low compared to a conventional cellular mobile communication network. In addition, since the service area is wide and the radio wave interference is small, the service can be performed at high speed while moving. Accordingly, the mobile WiMAX system is emerging as a next generation wireless communication technology capable of meeting user's desire for rapidly increasing wireless Internet service.

The services provided by the mobile WiMAX system include UGS (Unsolicited Grant Service), ERT-VR (Extended Real-Time Variable Rate) service, RT-VR (Real-Time Variable Rate) service, NRT-VR according to service requirements. It is classified into Non-Real-Time Variable Rate (BE) service and BE (Best Effort) service. The UGS is a service for allocating a resource of a certain size per cycle, which is a service for an application such as Voice over Internet Protocol (VoIP), and the RT-VR requests new resource allocation per cycle, such as video streaming. It is a service for real-time applications that receive and generate packets of variable size. The ERT-VR service periodically allocates a certain resource when there is a packet to transmit, but repeatedly allocates or allocates less resource when there is no packet to transmit, thereby making it possible to use limited radio resources more efficiently than UGS. It is a service. The NRT-VR service is suitable for serving non real-time applications that require a minimum transmission rate, and the BE service basically does not require any service level. Different types of scheduling and resource management / allocation mechanisms have been implemented according to service classes to satisfy the quality of services having these different requirements.

1 is a block diagram of a communication system according to the prior art.

Referring to FIG. 1, the communication system includes a subnet # 1 (Subnet) 150, a subnet # 2 160, a core network 120 connecting the subnets # 1 and # 2, The PSTN 122 is connected to the coordinating network 120 and the Internet 124.

The subnet # 1 150 is an access control router (hereinafter referred to as 'ACR') # 1 100 and a base station (Radio Access Station, hereinafter referred to as 'RAS') # 1 to # 4 ( 102 to 108, and a mobile station # 1 (110), wherein the subnet # 2 (160) includes an ACR # 2 (130), RAS # 5 to # 8 (132 to 138), and a terminal. # 2 (Mobile Station) 140. At this time, the direction from the ACR to the terminal via the base station is called a down link, and the opposite direction is called an up link. The uplink / downlink service guarantees a quality of service (QoS) through each algorithm. Hereinafter, the scope of the discussion is limited to the downlink in the present invention.

2 is an internal configuration diagram of a base station according to the prior art.

Referring to FIG. 2, the channel card 200 of the base station is largely composed of a processor module 202, an interface buffer 204, and a modem module 206.

Downlink packets in the base station are serviced through the following process.

The processor module 202 buffers the packets received from the control station in the temporary storage buffer 208 for each connection, and through the interaction of the network processor unit (NPU) 210 and the modem scheduler 214, the RTC ( Packets stored in 208 are written to the interface buffer 204.

Packets stored in the interface buffer 204 are scheduled via the modem module 206 and transmitted wirelessly. The modem scheduler 214 calculates the scheduling priority of the packets for each connection in the interface buffer 204 in consideration of service requirements, channel environment, and fairness. The modem scheduler 214 selects the connection with the highest priority and services packets of that connection. In order to improve the quality of service of the real-time service, the real-time service is given an absolutely high priority compared to the non-real-time service so that the service delay can be shortened to reduce the transmission delay.

The processing speed of the processor module 202 is faster than the transmission speed of the radio channel, and the link capacity between the control station and the base station is also much larger than the radio channel capacity. In addition, the low-cost large-capacity memory is mainly used as the buffering memory of the temporary storage buffer 208 in the processor module 202, whereas the interface buffer 204 may simultaneously read and write at a precise time. High speed, low capacity memories such as Random Access Memory are used. That is, since the interface buffer 204 becomes a bottleneck in the downlink packet flow, the quality of service is greatly influenced by the method of managing the buffer.

In detail, the modem scheduler 214 schedules the packets to be output in order of high priority, reflecting the service requirements of each connection when transmitting packets wirelessly. On the other hand, when storing a packet from the processor module 202 to the interface buffer 204, it simply schedules each connection in a round-robin manner. The round robin method sequentially outputs packets stored in the temporary storage buffer 208 to the interface buffer 204 one by one. However, the modem module 206 outputs the packet from the interface buffer 204 in order of high service priority. Therefore, since a packet having a low service priority, such as a BE service, occupies the entire buffer, the service may be delayed due to a lack of available space for a packet having a high service priority, for example, a UGS or NRT-VR service. have.

That is, packets with high service priority existing in the interface buffer 204 are serviced preferentially over packets with low service priority by the modem scheduler 214. As a result, packets having a high service priority in the interface buffer 204 are output at a higher speed than packets having a low service priority, but packets flowing into the interface buffer 204 are each connected regardless of service priority. Poor input in round robin fashion. Accordingly, a packet input / output speed difference of the interface buffer 204 occurs, and as time passes, packets having a high service priority in the interface buffer 204 gradually decrease, and all available buffers of the interface buffer 204 are reduced. It may happen that the space is filled only with BE service packets with low service priority.

As a result, when the available space of the buffer becomes insufficient, the inflow of the packet is delayed until the available space occurs in order to prevent the overflow of the buffer. In this case, even if the packet is high priority, the delay time increases until the BE service packets in the buffer are serviced because there is no available space in the buffer.

As described above, in the interface buffer management scheme according to the round-robin scheme, there is a problem in that the priority of the service is inverted so that the quality of service is deteriorated and the service of packets having high priority is not guaranteed.

Accordingly, an object of the present invention, which was devised to solve the problems of the prior art operating as described above, is to provide a method and apparatus for providing differentiated interface buffer management according to the priority of a service class in a communication system.

Another object of the present invention is to provide a method and apparatus for setting a threshold value for each service class, and scheduling a corresponding service by comparing an available space size of a buffer with the threshold value.

It is still another object of the present invention to provide a method and apparatus for setting hysteresis or a timer to prevent unnecessary service suspension and resumption.

It is still another object of the present invention to provide a method for retransmitting a service stop / resume signal message when a base station does not receive the service stop / resume signal confirmation message within a predetermined time when a service stop / resume signal message is transmitted; It is to provide a device.

In accordance with an aspect of the present invention, a method for managing a buffer of a base station in a communication system includes scheduling packet input / output of a buffer according to a priority of a service class. Setting a threshold value for each service class for each service, estimating and storing an available space size of the buffer after receiving the packet, and receiving a packet corresponding to the first service class of the packet. And comparing the threshold value with the estimated available space size of the buffer to schedule packet input / output of the buffer.

In accordance with another aspect of the present invention, an apparatus for managing a buffer of a base station in a communication system includes setting a threshold value for each service class for scheduling packet input / output of the buffer according to a priority of a service class. When the packet is received in the buffer, the received space size of the buffer is estimated and stored after the packet is received, and the first threshold value corresponding to the first service class of the packet is compared with the estimated space size of the buffer. And a buffer available space determining unit for instructing scheduling of packet input and output of the buffer, and a processor module for scheduling packet input and output of the buffer according to the instruction of the buffer available space determining unit.

The present invention described above is not limited to the above-described embodiment and the accompanying drawings, and various substitutions, modifications, and changes can be made without departing from the spirit of the present invention. It will be apparent to those who have knowledge.

The present invention improves the quality of the corresponding services through buffer management in consideration of the characteristics of the service traffic and service differentiation based on the priority of the service class, and protects the service of the packet having a high priority from the packet having a low priority. It is possible to ensure the quality of service and channel efficiency. In addition, when the size change of the buffer has a slight difference from the threshold for determining service interruption and resumption for each service class, a hysteresis period or a timer may be defined to prevent unnecessary repetition of the point of time when the service interruption and resumption is switched. It can be effective. In addition, by transmitting a message indicating when the service is suspended or resumed, and retransmitting the message depending on whether or not to receive a confirmation message of the message for a certain time, there is an effect of reducing the lost signal.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First, it should be noted that in the drawings, the same components or parts denote the same reference numerals as much as possible. In describing the present invention, detailed descriptions of related well-known functions or configurations are omitted in order not to obscure the subject matter of the present invention.

The present invention provides a method and apparatus for differentiating packets according to the size of the available space of the buffer by presetting a virtual dedicated buffer space of the interface buffer for each service class, and the size of the buffer according to the requirements of each service class. We propose a method and apparatus to determine. In the following description, a device to which a buffer allocation technique is applied assumes a base station, and the buffering scheme of the present invention may be equally applied to other devices requiring buffering in addition to the base station. According to the first embodiment of the present invention, a threshold having an optimal size of the available space of the buffer is determined for each service class. In the second embodiment of the present invention, a threshold value or a timer is set to reduce unnecessary switching of the service interruption and resumption of the corresponding service by comparing the threshold value for each service class and the change in the available space size of the buffer. Thereafter, according to the first to second embodiments, the service is stopped / resumed.

3 is a conceptual diagram of managing an interface buffer according to a first embodiment of the present invention. Here, an example of three service classes, RT service class sensitive to time delay, NRT service class having high priority regardless of time delay, and BE service class having no service requirement will be described as an example. In this case, it is assumed that the UGC, RT-VR service, and ERT-VR service class are mapped to the RT service class.

Referring to FIG. 3, a method of setting an optimal threshold value for each service class is as follows.

The amount of space available in the entire interface buffer 300 is defined as B_a 302, and threshold values for the RT, NRT, and BE service classes are defined as B_RT, B_NRT, and B_BE, respectively. Here, the B_RT, the B_NRT, and the B_BE mean a reference value for determining whether to input / output a packet for a corresponding service class.

The priority of the service classes is 'RT> NRT> BE'. At this time, the threshold values of the service classes are set in the order of 'B_RT <B_NRT <B_BE'. At this time, the threshold values of the service classes are set using an appropriate Call Admission Control (CAC) algorithm considering the required capacity for the corresponding service class and the transmission speed of the wireless channel.

First, since the RT has the highest priority, the value of the B_RT is set to '0' so as not to stop the service as long as the available space of the interface buffer exists. Secondly, the NRT is configured to secure the virtual dedicated buffer space for the RT service class to protect the traffic of the RT service class. That is, the buffer amount required for stable service of the RT service class is calculated and set to the B_NRT value. Thereafter, when the B_a 302 becomes less than the set B_NRT value, the NRT service and the BE service are stopped to protect the traffic of the RT service class.

Finally, the B_BE secures virtual dedicated buffer spaces of the RT service class and the NRT service class having priority over the BE service class, and then sets the value to protect traffic of the RT service class and the NRT service class. do. That is, the buffer amount required by the RT and NRT service classes is calculated and set to the B_BE value. Thereafter, when the B_a 302 falls below the B_BE, the BE service is stopped and only the NRT and RT service classes are available.

Hereinafter, a procedure of determining a corresponding service class flowing into the interface buffer 300 according to the size of the B_a 302 and threshold values of other service classes through Equations 1 to 3 will be described. Explain.

0 <B_a ≤ B_NRT

That is, when the B_a 302 is larger than 0 and smaller than B_NRT, only packets of the RT service class may flow into the interface buffer 300.

B_NRT <B_a ≤ B_BE

That is, when the B_a 302 is larger than the B_NRT and smaller than the B_BE, only packets of the RT and NRT service classes may be introduced.

B_a> B_BE

That is, when the B_a 302 is larger than the B_BE, all packets can be introduced.

Hereinafter, a method of setting threshold values of respective service classes in the present invention will be described with specific examples.

First, a specific example of setting the threshold value of the NRT service class required for the RT service class will be described.

First, the amount of buffer considering UGS is calculated. In this case, although the transmission speed varies depending on the voice codec used, most of the times, the maximum transmission speed is VoIP which does not exceed 100 Kbps. Considering that the sampling period of VoIP packets is about 20ms and additional time delay may occur due to factors such as jitter, suppose that the transmission interval between packets is 40ms. Then, since the size of the buffer required for one connection of VoIP is 'the product of the maximum transmission rate and the transmission interval between packets', it is calculated as in Equation 4 below.

100 Kbps * 40ms = 12.5 Kbyte / s * 40 ms = 500B

In this case, assuming that the basic unit of the interface buffer is a block of 576 bytes, one buffer block is required per VoIP connection. Since the interface buffer is managed for each channel card, the buffer amount for each channel card is calculated.

For example, the maximum number of VoIP flows allowed in the WiBro mobile WiMAX system by the CAC algorithm is about 60 per subcell. At this time, if it is assumed that there are three subcells for each channel card, the required buffer amount per channel card is calculated as in Equation 5 below.

1 block / flow * 60 flows / subcell * 3 subcells / channel card = 180 blocks

Second, the buffer amount considering the RT-VR service and the ERT-VR service is calculated.

Considering the average downlink subcell throughput of the WiBro system, when the CAC algorithm is applied to RT-VR and ERT-VR services, up to 10 flows with an average transmission rate of 256 Kbps are accommodated per subcell. Up to about 40 flows with an average transmission rate can be accommodated per subcell. On the other hand, assuming a time delay of 20 ms from the moment the packet enters the interface buffer to the service through the modem scheduler, The transmission speed of an acceptable flow per block is calculated as shown in Equation 6 below.

576 * 8 bits / 20 ms = 230 Kbps

If the transmission rate required from the applications of the RT-VR service or the ERT-VR service is assumed to be approximately 64 Kbps to 1 Mbps, the maximum number of flows can be accommodated when the flow rate is 64 Kbps. This requires the largest amount of buffers. In this case, the total amount of buffer required to service 40 flows per one subcell is calculated by Equation 7 below.

1 block / flow * 40 flows / subcell * 3 of subcells / channel card = 120

Considering both the UGS case and the RT-VR (or ERT-VR) service case, the total block size required for the RT service is calculated as 300 blocks because the total of 180 blocks and 120 blocks is the sum total.

Third, an example of setting threshold values of the BE service class required for the RT service and the NRT service will be described. Here, it is assumed that the total amount of buffers required by the RT service class is 300 blocks calculated above.

When servicing the packet of the NRT service class, when the CAC algorithm is applied in consideration of the average downlink subcell throughput, the number of acceptable flows per subcell increases as the required transmission rate of the flow decreases. For example, a flow having an average transmission rate of 64 Kbps may accommodate up to approximately 100 per subcell. Therefore, the buffer amount required for the NRT service is calculated as in Equation 8 below.

1 block / flow * 100 flows / subcell * 3 of subcells / channel card = 300 blocks

Through the above calculation process, since the interface buffer needs 300 blocks of dedicated space for the RT service class and 300 blocks of dedicated space for the NRT service class, B_BE is set to 600 blocks.

Subsequently, the buffer amounts for satisfying the service requirements of the UGS, RT, and NRT service classes are calculated using Equations 5 to 8. In this case, the total size of the interface buffer should be at least greater than the sum of the size values of the calculated buffer for each service class. That is, since the size of the buffer is set larger than the B_BE value, services of the UGS, RT, and NRT service classes are smoothly guaranteed.

Hereinafter, a signal processing method for stopping / resuming a service according to the first to second embodiments of the present invention will be described.

4 is an internal configuration diagram of a base station according to the first embodiment of the present invention.

Referring to FIG. 4, the channel card 400 of the base station is largely composed of a processor module 410, an interface buffer 420, and a modem module 430. The processor module 410 includes a message receiver 412 and a service stop flag (SSF) setting unit 414, and the interface buffer 420 has a buffer available space. The determination unit 422 and the SSF irradiation unit 424 are configured. Here, a case of processing downlink packets serviced by the base station will be described as an example.

The buffer available space determiner 422 estimates the size of the available space of the interface buffer 420 each time a received packet is input / output, and when the size becomes smaller than a specific threshold set for each service class. In order to stop the packet flow of the service class, the service stop message is issued. That is, the buffer available space determiner 422 compares the size of the available space of the interface buffer 420 with a preset threshold value when a packet of a specific service class flows into the interface buffer 420. . When the comparison result is smaller than the threshold value, the service stop message of the corresponding service class is transmitted to the message receiver 412 through a separate signal channel.

When the processor module 410 receives the service stop indication message, the SSF setting unit 414 sets the 'Service Stop Flag (hereinafter referred to as' SSF') of the corresponding service class to 'ON'. A service stop confirmation message is transmitted to the buffer available space determiner 422. If the buffer available space determiner 422 does not receive the service stop confirmation message for a predetermined time, the buffer available space determiner 422 sends the service stop message to the message receiver 412. Resend.

Meanwhile, when a packet is transmitted from the processor module 412 to the interface buffer 404 in a round-robin manner for each connection, the SSF inspector 424 examines the SSF of the corresponding connection service class. When the SSF of the service class is set to 'ON', the processor module 410 does not transmit a packet of a corresponding connection, but examines the service class of another connection according to a round robin order to give priority. Send packets of high service class to the interface buffer 420.

On the other hand, when a packet of a specific service class is serviced, when the SSF of the corresponding service class is preset and the size of the available space of the interface buffer 420 is larger than the preset threshold, the buffer available space determination unit ( 422 transmits a service resume message for releasing service suspension of the corresponding service class through the specific signal channel. When the message receiving unit 412 receives the service resume message, the SSF setting unit 414 sets the SSF of the corresponding service class to 'OFF' and sets the service resume confirmation message to the buffer available space determiner ( 422). If the buffer available space determiner 422 does not receive the service resume confirmation message for a predetermined time, the buffer available space determiner 422 sends the service stop instruction message to the message receiver 412. Resend to.

In the second embodiment of the present invention, the buffer available space determination unit 422 estimates the size of the available space of the interface buffer 420 each time a received packet is input / output, and sets each service class. One particular threshold value is added to or subtracted from the hysteresis threshold delta and compared with the estimated amount of available space.

That is, when the estimated amount of available space is smaller than a value obtained by subtracting delta from a specific threshold set for each service class, the buffer available space determiner 422 separates a signal channel to stop the packet inflow of the service class. The service stop message of the corresponding service class is transmitted to the message receiving unit 412 through.

On the other hand, when the estimated size of the available space is larger than the sum of the deltas and the threshold value, the buffer available space plate end 422 is used for the service through the specific signal channel to resume packet inflow of the suspended service. Send a service resume message to release the service from the class. The delta is an arbitrary threshold value set to prevent unnecessary service suspension / resume switching when there is no difference between the estimated size of available space and a specific threshold value for each service class. The delta may be set differently or identically for each service class.

For example, when the estimated size of B_a changes around B_BE (or B_NRT), B_a does not change the service stop / resume state within the following Equation (9).

B_BE + delta <B_a <B_BE + delta

In the second embodiment of the present invention, the buffer available space determination unit 422 estimates the size of the available space of the interface buffer 420 whenever the received packet is input / output, and the estimated available space. Compares a specific threshold value whose size is set for each service class. In this case, when the estimated size of the available space moves near the threshold, a timer is set to prevent a problem of unnecessary and repetitive transmission of service interruption and resume signals. That is, a stop-timer for determining a service interruption time and a resume timer for determining a restart time of the corresponding service, wherein the time at which the estimated size of the available space changes to a range in which there is no difference from the threshold value is determined. If it is less than the time set in replay-timer, unnecessary service interruption and resume switching or message transmission / reception can be prevented.

The timer may be set to an integer multiple of a frame duration, which is the minimum unit of a radio frequency scheduler, or may be set to a predetermined time without distinguishing each service class, or may be set differently for each service class.

Specifically, when the estimated size of the available space is smaller than the threshold, the buffer available space determiner 422 stops a preset time for staying in a state where the estimated size of the available space is smaller than the threshold. If the timer is greater than or equal to the time set, the service is stopped. Thereafter, the buffer available space determiner 422 transmits a service stop message of the corresponding service class to the message receiver 412 through a separate signal channel.

 On the other hand, when the estimated size of the available space is larger than the threshold, the buffer available space determiner 422 sets a resumption timer that has been set in advance for the time in which the estimated size of the available space is larger than the threshold. If it is greater than or equal to the time set in, resume the service. Thereafter, the buffer available space determiner 422 transmits a service stop message of a corresponding service class to the message receiver 412 through a separate signal channel. FIG. 5 is an interface buffer according to a first embodiment of the present invention. If the packet is input to the flow chart showing the operation of the buffer available space determination unit.

Referring to FIG. 5, if there is a packet received from the processor module, the interface buffer proceeds to step 505. In step 505, the interface buffer estimates and stores the size of the buffer available space B_a which is reduced after the packet is received.

In step 510, the interface buffer compares whether the size of B_a is smaller than a predetermined size of B_BE. If the comparison result is small, in step 515, the interface buffer stops the BE service, that is, stops the packet inflow of the BE service class, and proceeds to step 525. If the comparison result is greater than or equal to, in step 520, the interface buffer continues to introduce packets of the BE service class.

In step 525, it is compared whether the size of B_a is smaller than a predetermined B_NRT. If the comparison result is small, in step 530, the interface buffer stops the NRT service, that is, stops the packet inflow of the NRT service, and returns to step 500. If greater than or equal to the comparison result, in step 500, the interface buffer continues to introduce packets of the NRT service class.

6 is a flowchart illustrating an operation when a packet is output to an interface buffer according to a first embodiment of the present invention.

Referring to FIG. 6, in step 600, the interface buffer proceeds to step 605 when a packet to be transmitted is generated. In step 605, the interface buffer estimates and stores the size of the buffer available space B_a after the packet transmission.

In step 610, the interface buffer compares whether the size of B_a is greater than or equal to a predetermined size of B_nrt. If the comparison result is large, in step 620, the interface buffer resumes the NRT service that has been stopped and proceeds to step 625. If the comparison result is small, in step 615, the interface buffer continues to maintain the stopped NRT service. In step 625, it is compared whether the size of B_a is larger than a predetermined B_BE. If the comparison result is greater than or equal to 1, in step 630, the interface buffer resumes the BE service which has been suspended, and returns to step 600.

If the comparison result is small, in step 615, the interface buffer continues to stop the BE service.

7 is a flowchart illustrating an operation when a packet is input to an interface buffer according to a second embodiment of the present invention.

Referring to FIG. 7, in step 700, if there is a packet received from the processor module, the interface buffer proceeds to step 705. In operation 705, the interface buffer estimates and stores the size of the buffer available space B_a that is reduced after the packet is received.

In step 710, the interface buffer compares whether the size of the B_a is smaller than the size of a value obtained by subtracting delta from a predetermined B-BE. If the comparison result is small, the interface buffer transmits a BE service stop message in step 715, and proceeds to step 720. If greater than or equal to the comparison result, the process returns to step 700.

In step 720, the interface buffer checks whether a BE service stop confirmation message is received. If the BE service stop confirmation message is not received as a result of the check, the BE service stop message is retransmitted.

In response to receiving the BE service stop confirmation message as a result of the check, in step 730, the interface buffer recognizes that the BE service is stopped, and compares whether the size of B_a is smaller than the size of B_NRT minus delta. If greater than or equal to the comparison result, the process returns to step 700.

If the comparison result is small, the interface buffer transmits an NRT service stop message in step 740, and then proceeds to step 745.

In step 745, the interface buffer checks whether an NRT service stop confirmation message is received. When the NRT service stop confirmation message is received as a result of the check, the interface buffer recognizes that the NRT service is stopped in step 755, and returns to step 700. If the NRT service stop confirmation message is not received, the interface buffer retransmits the NRT service stop confirmation message in step 750.

8 is a flowchart illustrating an operation when a packet is output to an interface buffer according to a second embodiment of the present invention.

Referring to FIG. 8, if there is a packet received from the processor module in step 800, the interface buffer estimates and stores the size of the buffer available space Ba increased after the packet is received in step 805. do.

In step 810, the interface buffer compares whether the size of the B-a is larger than the size of a predetermined value of the B-NRT plus delta. If the comparison result is large, in step 820, the interface buffer transmits the suspended NRT service resume message, and then proceeds to step 825. If greater than or equal to the comparison result, the process returns to step 800.

In step 825, the interface buffer checks whether an NRT service resume confirmation message has been received. If the NRT service stop confirmation message is not received as a result of the check, the NRT service resume message is retransmitted.

When the NRT service resume confirmation message is received as a result of the check, in step 835, the interface buffer recognizes that the NRT service is resumed, and compares whether the size of B_a is larger than the size of B_BE plus delta. If the comparison is large, the process returns to step 800.

 If the comparison result is small, in step 840, the interface buffer transmits a BE service resume message, and then proceeds to step 845.

In step 845, the interface buffer checks whether a BE service resume confirmation message is received. In step 855, if the BE service resume confirmation message is received as a result of the check, it is recognized that the BE service is resumed and the process returns to step 800. If the BE service resume confirmation message is not received, the interface buffer retransmits the BE service resume confirmation message in step 850.

9 is a flowchart illustrating an operation of an interface buffer according to a second embodiment of the present invention.

Referring to FIG. 9, when the interface buffer receives a packet in step 900, the process proceeds to step 905. In step 905, the interface buffer determines whether the size of the buffer available space B_a_n changed due to the packet is increased or decreased than the size of the buffer available space B_a_n-1 before the B_a_n.

If the result of the check decreases, that is, the B_a_n is smaller than the B_a_n-1, the process proceeds to step 915. If the result of the check increases, that is, if the B_a_n is larger than the B_a_n-1, the process proceeds to step 920.

In step 915, the interface buffer compares whether B_a_n is smaller than B_BE. If the comparison is not small, the process returns to step 900. If the comparison result is small, in step 925, the interface buffer executes the service interruption timer in step 925, and proceeds to step 930.

In step 930, the interface buffer checks whether the intermediate timer has expired, and returns to step 900 if it has not expired. If the check result expires, in step 935, B_a is estimated again in consideration of a change in the available buffer size during the timer time (B_a_n + 1), and in step 940, if B_a_n + 1 is smaller than the B_BE, in step 945 In step 950, the interface buffer transmits a BE service stop message.

In step 950, the interface buffer determines whether the BE service stop confirmation message is received. If the BE service stop confirmation message is received as a result of the check, the interface buffer stops the BE service in step 1000 and returns to step 900. If the BE service stop confirmation message is not received as a result of the check, in step 955, the interface buffer retransmits the BE service stop confirmation message.

In step 920, the interface buffer compares whether B_a_n is larger than B_NRT. If the comparison is not large, the process returns to step 900. If the comparison result is large, the interface buffer executes a service resume timer in step 960, and proceeds to step 965.

In step 965, the interface buffer checks whether the intermediate timer has expired, and returns to step 900 if it has not expired. If the check result expires, B_a is estimated again in consideration of a change in the available buffer size during the timer time in step 970 (B_a_n + 1), and greater than B_NRT in step 975]. After transmitting the NRT service resume message, the process proceeds to step 985.

In step 985, the interface buffer determines whether the NRT service resume confirmation message has been received. If the NRT service resume confirmation message is received as a result of the checking, the interface buffer resumes the NRT service in step 990 and returns to step 900. If the BE service interruption confirmation message is not received, the interface buffer retransmits the NRT service resume confirmation message in step 995.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications may be made without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by those equivalent to the scope of the claims.

1 is a block diagram of a communication system according to the prior art.

2 is an internal configuration diagram of a base station according to the prior art.

3 is a conceptual diagram of managing an interface buffer according to a first embodiment of the present invention;

4 is an internal configuration diagram of a base station according to the first embodiment of the present invention.

5 is a flowchart illustrating an operation when a packet is input to an interface buffer according to a first embodiment of the present invention.

6 is a flowchart illustrating an operation when a packet is output to an interface buffer according to the first embodiment of the present invention.

7 is a flowchart illustrating an operation when a packet is input to an interface buffer according to a second embodiment of the present invention.

8 is a flowchart illustrating an operation when a packet is output to an interface buffer according to a second embodiment of the present invention.

9 is a flowchart illustrating an operation of an interface buffer according to a second embodiment of the present invention.

Claims (21)

In the communication system for managing a buffer of the base station, Setting a threshold value for each service class for scheduling packet I / O of the buffer according to the priority of the service class; When the packet is received in the buffer, estimating and storing an available space of the buffer after receiving the packet; And scheduling a packet input / output of the buffer by comparing a first threshold value corresponding to the first service class of the packet with the estimated available space of the buffer. The method of claim 1, wherein the scheduling process comprises: Stopping the service of the first service class and stopping the packet inflow of the first service class when the estimated space available size of the buffer is smaller than the first threshold value. The method of claim 2, Transmitting a first service interruption message indicating service interruption of the first service class to a service processor module; Stopping a service of the first service class when receiving a first service stop confirmation message from the service processor module; And retransmitting the first service interruption message to the processor module if the first service interruption confirmation message is not received from the processor module during a preset retransmission time interval. The method of claim 1, wherein the scheduling process comprises: And resuming a packet inflow of the previously suspended first service class if the available space size of the estimated buffer is greater than or equal to the first threshold value. The method of claim 4, wherein Transmitting a first service resume message indicating service resumption of the first service class to a service processor module; Resuming the first service when receiving the first service resume confirmation message from the processor module; If the first service resume confirmation message is not received from the processor module, retransmitting the first service resume message to the processor module for a preset retransmission time interval. The method of claim 1, The service class is A buffer management method comprising a real-time (RT) service class, a non-real-time (NRT) service class, and a best effort (BE) service class. The method of claim 6, And determining a total size of the buffer within a size range of available space that guarantees a predetermined performance for each of the RT service class and the NRT service class. delete The method of claim 1, wherein the scheduling process comprises: Determining a second threshold value which is a minimum variation for determining when to stop and resume service of the first service class; Stopping the service of the first service class and stopping the packet inflow of the first service class when the available space of the estimated buffer is smaller than the difference between the first threshold value and the second threshold value. How to manage. The method of claim 9, wherein the scheduling process comprises: Resuming the service of the first service class and resuming the packet inflow of the first service class if the available space of the estimated buffer is greater than the sum of the first threshold value and the second threshold value. How to manage. The method of claim 1, wherein the scheduling process comprises: Determining a time interval for determining when to stop and resume the first service; Driving a timer set to the time interval when the available space of the estimated buffer is smaller than the first threshold value; Stopping the packet inflow of the first service class when the available space size of the buffer estimated after the timer is less than the first threshold value. The method of claim 11, wherein the scheduling process comprises: Determining a time interval for determining when to stop and resume service of the first service class; Driving a timer set to the time interval when the available space size of the estimated buffer is greater than the first threshold value; And resuming packet inflow of the first service class when the available space size of the buffer estimated after the timer time is greater than the first threshold value. An apparatus for managing a buffer of a base station in a communication system, Sets a threshold value for each service class for scheduling packet input / output of the buffer according to the priority of the service class, estimates the available space of the buffer after receiving the packet, and stores the received packet when the packet is received into the buffer, A buffer available space determiner for instructing scheduling of packet input / output of the buffer by comparing a first threshold value corresponding to the first service class of the packet with the estimated available space size of the buffer; And a processor module configured to schedule packet input / output of the buffer according to an instruction of the buffer available space determiner. The method of claim 13, wherein the buffer available space determination unit, If the estimated space available in the buffer is smaller than the first threshold, a first service interruption message indicating a service interruption of the first service class is transmitted to the processor module, and the first service interruption confirmation is confirmed from the processor module. When receiving the message, recognizes that the service of the first service class is stopped, And when the first service interruption confirmation message is not received from the processor module for a preset retransmission time interval, retransmit the first service interruption message to the processor module. The method of claim 14, wherein the buffer available space determination unit, If the estimated available space size of the buffer is greater than the first threshold value, a first service resume message is sent to the processor module informing the resumption of service of the interrupted first service class, and the first service resume confirmation is confirmed from the processor module. When receiving the message, recognizes that the service of the first service class is resumed, And if the first service resume confirmation message is not received from the processor module during a preset retransmission time interval, retransmit the first service resume message to the processor module. The method of claim 13, The service class is And a real-time (RT) service class, a non-real-time (NRT) service class, and a best effort (BE) service class. The method of claim 16, And a buffer size determiner configured to determine a total size of the buffer within a size range of available space for guaranteeing predetermined performance for each of the RT service class and the NRT service class. delete The method of claim 13, wherein the buffer available space determination unit, Determining a second threshold value, which is a minimum variation for determining when to stop and resume service of the first service class, and if the estimated space available in the buffer is smaller than the difference between the first threshold value and the second threshold value, Send a first service stop message to the processor module, and if the estimated space available in the buffer is greater than the sum of the first threshold value and the second threshold value, a first service resume message to the processor module; Buffer management device. The method of claim 13, wherein the buffer available space determination unit, After determining a time period for determining a service interruption and resumption time of the first service class, and if the estimated available space of the buffer is less than the first threshold value, after driving the timer set to the time period, And when the available space of the buffer estimated after the time period expires of the timer is smaller than the first threshold, the first service interruption message is transmitted to the processor module. The method of claim 20, wherein the buffer available space determination unit, When the available space size of the estimated buffer is greater than the first threshold value, the timer set to the time period is driven, and the available space size of the estimated buffer after the time period expires of the timer is greater than the first threshold value. And if greater, transmitting a first service resume message to the processor module.

Images