KR101395949B1 - A method of allocating radio resources of radio bearers having priorities in a wireless communication system - Google Patents

Abstract

A method of allocating radio resources for a plurality of logical channels having the same priority, comprises the steps of: calculating a sum of a bit rate of radio resources allocated for the plurality of logical channels and a priority bit rate (PBR) of the plurality of logical channels And allocating radio resources to each logical channel over a plurality of transmission time intervals (TTIs) when the bit rate of the allocated radio resource is smaller than the sum of the PBRs of the plurality of logical channels. A method for allocating radio resources to a plurality of radio bearers having the same priority is provided.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a radio resource allocation method for a radio bearer having a priority in a radio communication system,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to wireless communication, and more particularly, to a radio resource allocation method for a radio bearer having a priority in a radio communication system.

A 3rd Generation Partnership Project (3GPP) mobile communication system based on WCDMA (Wideband Code Division Multiple Access) wireless access technology is widely deployed all over the world. HSDPA (High Speed Downlink Packet Access), which can be defined as the first evolutionary phase of WCDMA, provides the 3GPP with highly competitive wireless access technology in the mid-term future. However, since the development of wireless access technology that continues to increase and compete with the requirements and expectations of users and operators continues, development of new technologies in 3GPP is required for future competitiveness. Reduced cost per bit, increased service availability, the use of flexible frequency bands, simple structure and open interfaces, and proper power consumption of terminals are becoming a requirement.

The wireless communication system should provide various wireless services such as web browsing, Voice over Internet Protocol (VoIP), and the like as well as a simple voice service. In order to provide various wireless services, at least one radio bearer (RB) must be established between the base station and the terminals. A plurality of radio bearers can be set up to support various applications and simultaneously provide various radio services.

The RB may be a logical link provided by the first and second layers of the wireless protocol between the UE and the BS. One logical channel is allocated to one RB, and a plurality of logical channels for a plurality of RBs can be multiplexed and transmitted in one transport channel.

Each RB may have a different logical channel priority or the same logical channel priority. Hereinafter, a general radio resource allocation method according to logical channel priority will be described.

First, when each RB has different logical channel priorities, the UE can determine the amount of data to be transmitted for each RB using a following rule for a given radio resource at each transmission in the MAC.

Determines the amount of data to be transmitted in descending order of logical channel priorities for the multiplexed RBs, and determines the amount of data to be transmitted corresponding to the maximum PBR (Prioritized Bit Rate) in each RB. If there is radio resources remaining, MBRs are allocated to the multiplexed RBs in descending order of logical channel priorities. For example, if the value of the logical channel priority is 1 to 8, 1 is the highest priority and 8 is the lowest priority.

Next, when each RB has the same logical channel priority, the same amount of transmission can be allocated to each RB.

The PBR is the minimum bit rate guaranteed for the RB, which means that the wireless communication system should be able to provide that bit rate even if the wireless environment is very bad. The range of PBR can be set from 0 to infinity.

The logical channel priority and PBR of each RB are transferred from the RRC of the network to the RRC of the terminal through the RB setup message when the RB is initially set. The RRC of the terminal that has received the RB setup message sets up the required RB, and delivers the logical channel priority of each RB and the PBR information to the MAC of the terminal. The MAC that receives this information determines the transmission rate of each RB for the given radio resource per transmission time interval (TTI) according to the above rule. Hereinafter, a TTI is referred to as a time required to transmit one transport channel.

FIG. 1 shows an example of allocating radio resources for each logical channel.

Here, the PBR is designated by the base station. RBG # 1 is composed of RB1 and RB2, and RBG # 2 is composed of RB3, RB4 and RB5. The RB1 has a PBR of 200, the RB2 has a PBR of 300, the RB3 has a PBR of 100, the RB4 has a PBR of 100, and the RB5 has a PBR of 100. The priorities of the plurality of RBs in the same RBG are the same, and the priority among the RBGs is different. That is, the priority of RBG # 1 is higher than that of RBG # 2, the priority of RB1 and RB2 is the same, and the priority of RB3, RB4 and RB5 are the same.

Referring to FIG. 1, in order to satisfy the PBR of all RBs in RBG # 1 and RBG # 2, a radio resource of 800 bit rate is required. However, if only a radio resource of 600 BR is allocated for each TTI, 500BR is allocated to RBG # 1 having a higher priority and RBR # 2 is assigned to the remaining 100BR. Here, radio resources can be allocated to RB3, RB4, and RB5 in RBG # 2 having the same priority in the same manner by 30 BRs.

According to the method shown in FIG. 1, if the PBR of each RB of RBG # 2 is not satisfied and the radio resource 100BR allocated to RBG # 2 is allocated to three RBs, the padding bits of 10BR remain Resulting in wasting wireless resources. In addition, in the case of video data that is vulnerable to jitter, a problem may occur that the screen is cut off. In addition, when there is a change in radio resource allocation according to a buffer status report (BSR), RLC PDU re-segmentation may occur. Overhead may occur because the header is added when the RLC PDU is re-divided.

FIG. 2 is a diagram illustrating a structure of an RLC PDU in an AM (acknowledgment mode) RLC, and FIG. 3 is a diagram illustrating a structure of a divided RLC PDU in an AM RLC. Referring to FIG. 2 and FIG. 3, when the RLC PDU is divided, data of about 2 octets including an SO field is added to the header part, and overhead occurs.

With the development of mobile communication technology, various applications can be realized in one terminal and various services can be provided at the same time. In particular, when a plurality of radio bearers having the same priority are simultaneously set up, such as using a plurality of web browsers at the same time, there is a risk that the quality of the service will deteriorate unless there is a clear data processing method therefor.

SUMMARY OF THE INVENTION The present invention provides a method for allocating radio resources to a plurality of radio bearers having the same priority.

A method of allocating a radio resource for a plurality of logical channels having the same priority according to an aspect of the present invention includes allocating a bit rate of a radio resource allocated for the plurality of logical channels and a priority bit of a plurality of logical channels Rate, and PBR) of a plurality of logical channels, and comparing radio resources to each logical channel over a plurality of transmission time intervals (TTIs) when the bit rate of the allocated radio resources is less than the sum of the PBRs of the plurality of logical channels .

A method of allocating radio resources of a plurality of radio bearers according to another aspect of the present invention is characterized in that one radio bearer group includes at least one radio bearer having the same priority and radio resources are allocated in descending order of priority of each radio bearer group And allocating radio resources to each radio bearer over a plurality of transmission time intervals (TTIs) if the bit rate of the radio resources allocated to one radio bearer group is less than the PBR of the radio bearer group do.

The priority for radio resource allocation for a plurality of radio bearers can be partially changed according to the buffer status, thereby reducing overhead due to signal generation, packet transmission delay and jitter.

4 is a block diagram illustrating a wireless communication system. This may be a network structure of an Evolved-Universal Mobile Telecommunications System (E-UMTS). The E-UMTS system may be referred to as an LTE (Long Term Evolution) system. Wireless communication systems are widely deployed to provide various communication services such as voice, packet data, and the like.

Referring to FIG. 4, an Evolved-UMTS Terrestrial Radio Access Network (E-UTRAN) includes a base station (BS) 20 that provides a control plane and a user plane.

A user equipment (UE) 10 may be fixed or mobile and may be referred to as another term such as a mobile station (MS), a user terminal (UT), a subscriber station (SS) The base station 20 generally refers to a fixed station that communicates with the terminal 10 and may be referred to as another term such as an evolved-NodeB (eNB), a base transceiver system (BTS), an access point have. One base station 20 may have more than one cell. An interface for transmitting user traffic or control traffic may be used between the base stations 20. Hereinafter, downlink refers to communication from the base station 20 to the terminal 10, and uplink refers to communication from the terminal 10 to the base station 20.

The base stations 20 may be interconnected via an X2 interface. The base station 20 is connected to an EPC (Evolved Packet Core), more specifically, an MME (Mobility Management Entity) / S-GW (Serving Gateway) 30 via an S1 interface. S1 interface supports many-to-many-relations between the base station 20 and the MME / S-GW 30.

5 is a block diagram illustrating a functional split between the E-UTRAN and the EPC.

Referring to FIG. 5, the hatched block represents a radio protocol layer, and the empty block represents a functional entity of a control plane.

The base station performs the following functions. (1) radio resource management such as radio bearer control, radio admission control, connection mobility control, and dynamic resource allocation to a terminal, (RRM) function, (2) Internet Protocol (IP) header compression and encryption of user data streams, (3) routing of user plane data to the S-GW, (4) Scheduling and transmission, (5) scheduling and transmission of broadcast information, and (6) measurement and measurement reporting setup for mobility and scheduling.

The MME performs the following functions. (2) security control, (3) idle state mobility control, (4) SAE bearer control, (5) NAS (Non-Access) Stratum signaling ciphering and integrity protection.

The S-GW performs the following functions. (1) termination of user plane packets for paging, and (2) user plane switching to support terminal mobility.

6 is a block diagram showing elements of a terminal. The terminal 50 includes a processor 51, a memory 52, an RF unit 53, a display unit 54, and a user interface unit 55 . The processor 51 implements layers of the air interface protocol to provide a control plane and a user plane. The functions of the respective layers can be implemented through the processor 51. [ The memory 52 is connected to the processor 51 and stores a terminal driving system, an application, and general files. The display unit 54 displays various information of the terminal and can use well known elements such as a liquid crystal display (LCD) and an organic light emitting diode (OLED). The user interface unit 55 may be a combination of a well-known user interface such as a keypad or a touch screen. The RF unit 53 is connected to the processor to transmit and / or receive a radio signal.

The layers of the radio interface protocol between the terminal and the network are classified into L1 (first layer), L2 (first layer), and L2 (third layer) based on the lower three layers of the Open System Interconnection (Second layer), and L3 (third layer). The physical layer belonging to the first layer provides an information transfer service using a physical channel, and a radio resource control (RRC) layer located at the third layer Controls the radio resources between the UE and the network. To this end, the RRC layer exchanges RRC messages between the UE and the network.

7 is a block diagram illustrating a radio protocol architecture for a user plane. 8 is a block diagram illustrating a wireless protocol structure for a control plane. This represents the structure of the radio interface protocol between the UE and the E-UTRAN. The data plane is a protocol stack for transmitting user data, and the control plane is a protocol stack for transmitting control signals.

Referring to FIGS. 7 and 8, a physical layer (PHY) layer of the first layer provides an information transfer service to an upper layer using a physical channel. The physical layer is connected to an upper layer MAC (Medium Access Control) layer through a transport channel, and data is transferred between the MAC layer and the physical layer through the transport channel. Data moves between physical layers between different physical layers, that is, between a transmitting side and a receiving physical layer. The physical channel is modulated by an Orthogonal Frequency Division Multiplexing (OFDM) scheme, and time and frequency can be utilized as radio resources.

The MAC layer of the second layer provides a service to a radio link control (RLC) layer, which is an upper layer, through a logical channel. The RLC layer of the second layer supports transmission of reliable data. There are three operation modes of the RLC layer according to the data transmission method, namely, a transparent mode (TM), an unacknowledged mode (UM), and an acknowledged mode (AM). The AM RLC provides a bi-directional data transmission service and supports retransmission when a RLC PDU (Protocol Data Unit) transmission fails.

The Packet Data Convergence Protocol (PDCP) layer of the second layer contains relatively large and unnecessary control information in order to efficiently transmit packets in a radio section having a small bandwidth during transmission of an IP (Internet Protocol) packet such as IPv4 or IPv6 And performs header compression to reduce the size of the IP packet header.

The third layer of Radio Resource Control (RRC) layer is defined only in the control plane. The RRC layer is responsible for the control of logical channels, transport channels and physical channels in connection with the configuration, re-configuration and release of radio bearers (RBs). RB denotes a service provided by the second layer for data transmission between the UE and the E-UTRAN. If there is an RRC connection between the RRC of the UE and the RRC of the network, the UE is in the RRC Connected Mode, and if not, the UE is in the RRC Idle Mode.

The non-access stratum (NAS) layer located at the top of the RRC layer performs functions such as session management and mobility management.

9 is a diagram illustrating a radio resource allocation method for a plurality of RBs having the same priority according to an embodiment of the present invention.

Here, the PBR is designated by the base station. RBG # 1 is composed of RB1 and RB2, and RBG # 2 is composed of RB3, RB4 and RB5. The RB1 has a PBR of 200, the RB2 has a PBR of 300, the RB3 has a PBR of 100, the RB4 has a PBR of 100, and the RB5 has a PBR of 100. The priorities of the plurality of RBs in the same RBG are the same, and the priority among the RBGs is different. That is, the priority of RBG # 1 is higher than that of RBG # 2, the priority of RB1 and RB2 is the same, and the priority of RB3, RB4 and RB5 are the same.

Referring to FIG. 9, a radio resource of 800BR is required to satisfy the PBR of all RBs in RBG # 1 and RBG # 2. However, if only a radio resource of 600 Bit Rate is allocated, 500BR is allocated to RBG # 1 having a higher priority and RBR # 2 is allocated to 100BR. Here, the PBR of each RB of RBG # 1 can be satisfied, but the PBR of each RB of RBG # 2 can not be satisfied. Accordingly, according to FIG. 9, uplink data is transmitted to each RB once every TTI period. That is, 100BR is allocated to RB3, 100BR is allocated to RB4 in the next TTI, and 100BR is allocated to RB5 in the next TTI.

Referring to FIG. 9, it is possible to solve the problem of padding bits and RLC PDU re-segmentation due to the resource allocation change according to the buffer status report. If resource allocation to the UE increases according to the buffer status report and resources of 300BR or more are allocated to RBG # 2, the corresponding operation can be stopped and PBR 100 can be allocated for each RB and transmitted.

10 is an exemplary diagram illustrating another method of allocating radio resources to a plurality of RBs having the same priority according to another embodiment of the present invention.

Here, the PBR is designated by the base station. RBG # 1 is composed of RB1 and RB2, and RBG # 2 is composed of RB3, RB4 and RB5. The RB1 has a PBR of 200, the RB2 has a PBR of 300, the RB3 has a PBR of 100, the RB4 has a PBR of 100, and the RB5 has a PBR of 100. The priorities of the plurality of RBs in the same RBG are the same, and the priority among the RBGs is different. That is, the priority of RBG # 1 is higher than that of RBG # 2, the priority of RB1 and RB2 is the same, and the priority of RB3, RB4 and RB5 are the same.

Referring to FIG. 10, a radio resource of 800BR is required to satisfy the PBR of all RBs in RBG # 1 and RBG # 2. However, if only a radio resource of 700 Bit (Bit Rate) is allocated, 500BR is allocated to RBG # 1 having a higher priority in the TTI and RBR # 2 is allocated to the remaining 200BR. Here, the PBR of each RB of RBG # 1 can be satisfied, but the PBR of each RB of RBG # 2 can not be satisfied. Therefore, according to FIG. 10, when the PBRs of the RBs of the RBG # 2 are the same, the RB with a small amount of buffer data is processed first. That is, when 200BR radio resources are allocated to the current RBG # 2, two RBs can be allocated for each TTI as much as the PBR.

For example, if the buffer data of RB3 is the smallest, radio resources of 100BR are allocated for RB3, and RB4 and RB5 use radio resources of the remaining 100BR for each TTI. When the buffer status of the RB 3 allocated to the radio resource of 100 BR is completely finished and the buffer status becomes 0, RB 4 and RB 5 allocate 100 BRs and transmit data. If RBG # 2 further includes RB6 having a PBR of 100, dedicated resources are allocated to the RBs having the smallest buffer data among RB4, RB5 and RB6 as the PBR.

If the RB having the smallest buffer data is preferentially processed, the size of the buffer status report message can be reduced to reduce the overhead. Therefore, the data service to process per RB can be completed early.

11 is an exemplary diagram illustrating another method of allocating radio resources to a plurality of RBs having the same priority according to another embodiment of the present invention.

Here, the PBR is designated by the base station. RBG # 1 is composed of RB1 and RB2, and RBG # 2 is composed of RB3, RB4 and RB5. RB1 has a PBR of 100, RB2 has a PBR of 200, RB3 has a PBR of 200, RB4 has a PBR of 150, and RB5 has a PBR of 100. The priorities of the plurality of RBs in the same RBG are the same, and the priority among the RBGs is different. That is, the priority of RBG # 1 is higher than that of RBG # 2, the priority of RB1 and RB2 is the same, and the priority of RB3, RB4 and RB5 are the same.

Referring to FIG. 11, in order to satisfy the PBR of all RBs in RBG # 1 and RBG # 2, a radio resource of 750 BR per TTI is required. However, if 500 RBs of radio resources are allocated per TTI, 300 BR is allocated to RBG # 1 having higher priority in the TTI, and remaining resources are allocated to RBG # 2. Here, the PBR of each RB of RBG # 1 can be satisfied, but the PBR of each RB of RBG # 2 can not be satisfied. 11, a bucket size is set in consideration of the delay characteristics and jitter of each RB in a manner of allocating radio resources in consideration of the buffer status, and a bucket size is set based on the PBR, which is a bucket rate, Is proposed. That is, in FIG. 11, since the PBR of RB3 is the largest, the bucket is fast, and the RB5 has the smallest PBR. Therefore, the transmission frequency of RB3 is set to the greatest, and the transmission frequency of RB5 is set to be the lowest, and transmission scheduling of RB3, RB4 and RB5 is performed for each TTI.

The present invention may be implemented in hardware, software, or a combination thereof. (DSP), a programmable logic device (PLD), a field programmable gate array (FPGA), a processor, a controller, a microprocessor, and the like, which are designed to perform the above- , Other electronic units, or a combination thereof. In software implementation, it may be implemented as a module that performs the above-described functions. The software may be stored in a memory unit and executed by a processor. The memory unit or processor may employ various means well known to those skilled in the art.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. It will be understood that various modifications and changes may be made without departing from the spirit and scope of the invention. Accordingly, modifications of the embodiments of the present invention will not depart from the scope of the present invention.

FIG. 1 shows an example of allocating radio resources for each logical channel.

2 is a diagram showing a structure of an RLC PDU in an AM (acknowledgment mode) RLC.

3 is a diagram showing a structure of a divided RLC PDU of AM RLC.

4 is a block diagram illustrating a wireless communication system.

5 is a block diagram illustrating a functional split between the E-UTRAN and the EPC.

6 is a block diagram showing elements of a terminal.

7 is a block diagram illustrating a radio protocol architecture for a user plane.

8 is a block diagram illustrating a wireless protocol structure for a control plane.

9 is a diagram illustrating a radio resource allocation method for a plurality of RBs having the same priority according to an embodiment of the present invention.

10 is an exemplary diagram illustrating another method of allocating radio resources to a plurality of RBs having the same priority according to another embodiment of the present invention.

11 is an exemplary diagram illustrating another method of allocating radio resources to a plurality of RBs having the same priority according to another embodiment of the present invention.

Claims (5)

A radio resource allocation method for a plurality of logical channels having the same priority, Comparing a bit rate of radio resources allocated to the plurality of logical channels with a sum of a priority bit rate (PBR) of the plurality of logical channels; And And allocating radio resources to each logical channel over a plurality of transmission time intervals (TTIs) when the bit rate of the allocated radio resource is less than the sum of the PBRs of the plurality of logical channels. Resource allocation method. The method according to claim 1, And allocating a radio resource to each logical channel in each TTI in order. The method according to claim 1, And allocating a radio resource to the preceding TTI preferentially according to the buffer data amount of each logical channel. The method according to claim 1, Wherein the frequency of allocating radio resources to the TTI is determined according to the PBR of each logical channel. Wherein one radio bearer group includes at least one radio bearer having the same priority, and allocating radio resources in descending order of priority of each radio bearer group; And And allocating radio resources to each radio bearer over a plurality of transmission time intervals (TTIs) when the bit rate of radio resources allocated to one radio bearer group is smaller than the PBR of the radio bearer group And allocating a radio resource to the plurality of radio bearers.

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