KR102164988B1 - Method of receiving data for user equipment - Google Patents

Abstract

A method for receiving data performed in a terminal to which dual connectivity is applied is disclosed. The terminal's data reception method is that the PDCP layer of the terminal receives at least one protocol data unit (PDU) from a lower layer, performs rearrangement of at least one protocol data unit, and then rearranges the service data unit (SDU) to an upper layer. ). Accordingly, it is possible to perform a seamless handover between different radio access technologies, and to guarantee quality of service.

Description

How to receive data from the terminal {METHOD OF RECEIVING DATA FOR USER EQUIPMENT}

The present invention relates to mobile communication technology, and more particularly, to a data receiving method of a terminal applicable to a terminal connected to a macro cell and a small cell at the same time.

Due to the widespread spread of portable mobile terminals and tablet PCs, and the rapid expansion of mobile computing based on wireless Internet technology, a significant increase in wireless network capacity is required.

Currently, the LTE (Long Term Evolution) system, which is a 4th generation mobile communication system, has been commercialized worldwide and provides users with a higher transmission rate compared to the 3rd generation mobile communication system, but it is insufficient to prepare for the explosion of mobile data.

At the 3GPP (3rd Generation Partnership Project)'s Long Term Evolution (LTE)-Advanced standardization meeting, technology for Small Cell Enhancement is being standardized in order to efficiently accommodate the rapidly increasing demand for mobile data. .

As a major issue of small cell enhancement technology, carrier aggregation between base stations, which is a dual connectivity technology in which a terminal is simultaneously connected to a macro base station and a small cell base station using multiple communication links, to provide services is drawing attention.

In order to simplify security and handover issues in dual connectivity technology, the PDCP (Packet Data Convergence Protocol) function is performed only at the macro base station, and the macro base station divides the PDCP's Protocol Data Unit (PDU). ) And transmitted to the small cell base station has been proposed. However, in such a user plane structure, there is a high probability that the order of PDUs is changed in the PDCP layer of the terminal to be received, and thus, a problem of deteriorating the quality of a user's experience may occur.

Meanwhile, mobile communication operators mainly use a method of offloading traffic to a WiFi network to prepare for an explosion of mobile data in a cellular network. However, in the current network structure, since the cellular network and the WiFi network are interlocked in the core network of the cellular network, there is a disadvantage in that it cannot provide seamless handover and quality of service (QoS).

An object of the present invention for solving the above-described problem is to provide a data receiving method of a terminal capable of delivering SDUs to a higher layer in an order from a PDCP layer of a terminal in an environment in which dual connectivity is applied to a terminal. will be.

In addition, another object of the present invention is to provide a network structure and a method for receiving data of a terminal to efficiently perform interworking between different radio access technologies.

A method of receiving data of a terminal according to an aspect of the present invention for achieving the object of the present invention described above includes the steps of receiving at least one protocol data unit (PDU) from a lower layer by a PDCP layer of the terminal, and the PDCP layer And performing the rearrangement of the at least one protocol data unit, and transmitting a service data unit (SDU) rearranged by the PDCP layer to an upper layer.

According to the data reception method of the terminal as described above, in a dual connectivity application environment in which the terminal is simultaneously connected to the macro base station and the small cell base station to provide services using multiple communication links, the order of PDUs in the PDCP layer of the terminal is reversed. When received, the order is guaranteed and delivered to the upper layer. Therefore, it is possible to improve the quality of the user's experience.

In addition, it provides a method for supporting dual connectivity in which a terminal is simultaneously connected to a base station of a cellular mobile communication network and an access point of a WiFi network to receive a service. Accordingly, seamless handover between different wireless access technologies such as a cellular mobile communication network and a WiFi network can be performed, and service quality can be improved through this.

1 shows examples of the configuration of a user plane of base stations for supporting dual connectivity.
2 is a flowchart illustrating a method of processing downlink data by a terminal according to an embodiment of the present invention.
3 is a flowchart illustrating a method of processing downlink data by a terminal according to another embodiment of the present invention.
4 is a flowchart illustrating a method of processing downlink data by a terminal according to another embodiment of the present invention.
5 is a conceptual diagram showing a general interworking structure between a cellular mobile communication network and a WiFi network.
6 is a conceptual diagram illustrating an interworking structure between a cellular mobile communication network and a WiFi network according to an embodiment of the present invention.
FIG. 7 is a conceptual diagram illustrating a data processing process of a terminal in an interworking structure between a cellular mobile communication network and a WiFi network as shown in FIG. 5.
FIG. 8 is a conceptual diagram illustrating a data processing process of a terminal in an interworking structure between a cellular mobile communication network and a WiFi network as shown in FIG. 6.

In the present invention, various modifications may be made and various embodiments may be provided, and specific embodiments will be illustrated in the drawings and described in detail.

However, this is not intended to limit the present invention to a specific embodiment, it is to be understood to include all changes, equivalents, and substitutes included in the spirit and scope of the present invention.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present application, terms such as "comprise" or "have" are intended to designate the presence of features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, but one or more other features. It is to be understood that the presence or addition of elements or numbers, steps, actions, components, parts, or combinations thereof, does not preclude in advance.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms as defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and should not be interpreted as an ideal or excessively formal meaning unless explicitly defined in the present application. Does not.

The'terminal' used in this application is a user equipment (UE), a mobile station (MS), a mobile terminal (MT), a user terminal, a user terminal (UT), a wireless terminal, Access Terminal (AT), Subscriber Unit, Subscriber Station (SS), Wireless Device, Wireless Communication Device, Wireless Transmit/Receive Unit (WTRU), Mobile Node, Mobile Or may be referred to by other terms.

In addition, the'base station' used in the present application generally refers to a fixed point communicating with the terminal, and the base station, node-B, eNode-B, BTS (Base Transceiver System), access point (Access Point), etc. may be called other terms.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings. In describing the present invention, in order to facilitate an overall understanding, the same reference numerals are used for the same elements in the drawings, and duplicate descriptions for the same elements are omitted.

1 shows examples of configuration of a user plane of base stations for supporting dual connectivity. In FIG. 1, when a macro base station (or Anchor eNB) and a small cell base station (or an assistant eNB) support dual connectivity to a terminal, four different user planes are illustrated as an example of a user plane of each base station. Here, the small cell base station may be configured as a base station or point conforming to the 3GPP LTE (or LTE-Advanced) standard, or may be configured as an access point (AP) conforming to the IEEE 802.11 Wireless Local Area Networks (or WiFi) standard. May be.

In addition, FIG. 1 shows an example of supporting dual connectivity for E-RAB1 among a plurality of E-UTRAN Radio Access Bearers (E-RABs). The PDCP (Packet Data Convergence Protocol), RLC (Radio Link Control), MAC (Medium Access Control) and PHY (Physical) layers shown in FIG. 1 each basically have functions defined in the 3GPP LTE standard standard or the IEEE 802.11 WLAN standard standard. Can be done with

Figure 1 (a) is a protocol layer for supporting E-RAB1, the macro base station 110 includes a PDCP (111), RLC (112), MAC (113) layer, the small cell base station 120 is a PHY (121) This shows the case where only the layer is included. When only the PHY (121) layer is present in the small cell base station 120, it can operate similarly to the existing carrier aggregation, but it is difficult to guarantee a hybrid automatic repeat request (HARQ) round trip time (RTT), making the HARQ operation complicated. there is a problem.

(B) of FIG. 1 is a protocol layer for supporting E-RAB1. The macro base station 130 includes a PDCP 131 and an RLC 132 layer, and the small cell base station 140 includes a MAC 141 and a PHY. (142) Shows the case of including a hierarchy. When the MAC (141) / PHY (142) layer is present in the small cell base station 140, the HARQ function can be normally performed, but the RLC 132 layer and the MAC 141 layer are separated to efficiently use radio resources. There is a drawback of not being able to use it.

1C is a protocol layer for supporting E-RAB1. The macro base station 150 includes a PDCP 151 layer, and the small cell base station 160 includes an RLC 161, a MAC 162, and a PHY. (163) Shows a case including a layer. When the RLC 161, MAC 162, and PHY 163 layers exist in the small cell base station 160, radio resources can be efficiently used. However, since the PDCP 151 layer and the RLC 161 layer are separated, an interface between the PDCP and RLC may not be efficient.

Figure 1 (d) is a protocol layer for supporting E-RAB1, the macro base station 170 does not include a PDCP, RLC, MAC, PHY layer for E-RAB1, the small cell base station 180, PDCP ( 181), RLC 182, MAC 183, and PHY 184 are included in the case. If the PDCP (181), RLC (182), MAC (183) and PHY (184) layers are present in the small cell base station 180, it can operate according to the standard protocol of the existing LTE system, but security and handover procedures are not required. There is a downside to being complicated.

Among the user planes shown in FIGS. 1A to 1D, the structure of the user plane shown in FIG. 1C is attracting attention as a structure that does not cause problems in performing an operation according to the protocol while increasing the data transmission rate of the user. have.

2 is a flowchart showing a method of processing downlink data by a terminal according to an embodiment of the present invention, and downlink data performed in the PDCP layer (or PDCP entity) of a terminal in which dual connectivity is supported by a macro cell and a small cell It is an illustration of the treatment method.

2, the PDCP layer of the terminal receives a PDCP Protocol Data Unit (PDU) whose PDCP SDU (Service Data Unit) sequence number (SN: Sequence Number, hereinafter, abbreviated as'SN') is an RSN from a lower layer. Do (S201).

The PDCP layer performs deciphering and header restoration on the received PDCP PDU, and stores the PDCP SDU in the PDCP buffer when the PDCP PDU is not discarded (S202).

The PDCP layer compares the SN (ie, RSN) of the received PDCP SDU with the NEXT value and sets the NEXT value to RSN+1 when the RSN is greater than or equal to the NEXT value (S203). Here, NEXT means the SN of the PDCP PDU to be received next by the PDCP layer.

The PDCP layer determines whether the received PDCP SDU has been received due to RLC re-establishment (S204).

If it is determined in step S204 that the PDP SDU has been received due to the RLC reconfiguration, the PDCP layer determines whether the SN (ie, RSN) of the received PDCP SDU is equal to LAST+1 (S205). Here, LAST means the SN of the last PDCP SDU delivered by the PDCP layer to the upper layer.

As a result of determination in step S205, if the RSN and LAST+1 are the same, the received PDCP SDU (SN=RSN) means that the received PDCP SDUs (SN=RSN) are received in an orderly manner. Therefore, the PDCP layer has a continuous SN greater than or equal to the RSN among the stored PDCP PDUs. PDCP PDUs with SNs are delivered to the upper layer as PDCP SDUs (S207).

Thereafter, the PDCP layer sets the SN of the last PDCP SDU delivered to the upper layer as the LAST value (S208).

If it is determined in step S205 that the RSN and LAST+1 are not the same, the PDCP layer suspends delivery of the SDU until the order of the PDCP SDUs is guaranteed through retransmission after the handover.

On the other hand, if it is determined in step S204 that the received PDCP SDU is received in a situation other than RLC reconfiguration, the PDCP layer sequentially delivers PDUs having an SN smaller than the RSN to the upper layer as PDCP SDUs (S206).

Thereafter, the PDCP layer delivers the PDCP SDU to the upper layer according to the order of the PDCP PDU SN by performing steps S207 and S208.

In a dual connectivity environment in which a terminal is simultaneously connected to a macro base station and a small cell base station through multiple links to provide services through carrier aggregation between base stations, the base stations are user planes as shown in FIG. 1(c). In the case of applying the structure, since the RLC layer of the link between the macro base station and the link between the mobile station and the small cell base station in the terminal individually performs reordering and in-sequence delivery, the terminal In the PDCP layer, the order of PDUs received from the lower layers is often reversed. Excluding the RLC reconfiguration, if the existing PDCP layer function of delivering SDUs to the upper layer in the order in which PDUs are received is performed as it is, the order of data is transferred to the upper layer in an inverted state, thereby reducing the user's service experience quality. A problem of deterioration occurs.

In order to solve the above-described problem in the present invention, a method of delivering PDUs received from the PDCP layer to a higher layer in order is provided.

3 is a flowchart illustrating a method of processing downlink data by a terminal according to another embodiment of the present invention, illustrating a method of processing downlink data of a PDCP layer when an RLC layer of a terminal operates in an unacknowledged mode (UM). . In FIG. 3, it is assumed that the PDCP layer of the terminal waits for reception of a missing PDCP SDU, and it is assumed that a timer t_loss_recovery for loss recovery is in operation.

Referring to FIG. 3, the PDCP layer of the UE determines whether the timer t_loss_recovery for loss recovery has expired (S301).

The PDCP layer stores the received PDCP SDU in the PDCP buffer when a PDCP PDU of which the SN is an RSN is received (S302) while the timer t_loss_recovery has not expired (S303). .

The PDCP layer compares the SN (ie, RSN) of the received PDCP SDU with the NEXT value and sets the NEXT value to RSN+1 when the RSN is greater than or equal to the NEXT value (S304).

Thereafter, the PDCP layer determines whether the RSN is the same as LAST+1, which is the SN value of the PDU that finally delivered the SDU to the upper layer (S305).

As a result of determination in step S305, if the RSN is the same as LAST+1, it means that the received SDUs have been delivered in order, so the PDCP layer checks whether the t_loss_recovery timer is operating and releases the operation when the t_loss_recovery timer is operated ( S306).

Thereafter, the PDCP layer delivers PDCP PDUs having consecutive SNs having an SN greater than or equal to the RSN among the stored PDCP PDUs as PDCP SDUs to a higher layer (S311).

Then, the PDCP layer sets the SN of the last PDCP SDU delivered to the upper layer as the LAST value (S312).

Thereafter, the PDCP layer compares the LAST+1 value and the NEXT value (S313). Here, when the LAST+1 value is different from the NEXT value, it means that at least one PDU has not been received between LAST+1 and NEXT. In this case, since the corresponding PDU may be received within a predetermined time, the PDCP layer drives the t_loss_recovery timer if the t_loss_recovery timer is not running and sets LR_SN to LAST+1 (S314). Here, LR_SN means the SN of the PDU to be lost.

If it is determined in step S305 that the RSN is not the same as LAST+1, the PDCP layer compares the RSN+1 value and the NEXT value, and compares the LAST+1 value and the NEXT value (S307).

As a result of the determination in step S307, if the LAST+1 value is different from the NEXT value, it means that at least one PDU has not been received between LAST+1 and NEXT. In this case, since the corresponding PDU may be received within a predetermined time, the PDCP layer drives the t_loss_recovery timer and sets LR_SN to LAST+1 if the t_loss_recovery timer is not running (S308).

Alternatively, when the RSN is the largest SN among the SNs of the PDUs received so far (that is, the RSN+1 value and the NEXT value are the same), it means that at least one PDU has not been received between the LAST and the RSN. In this case, too, since the corresponding PDU may be received within a certain time, the PDCP layer drives the t_loss_recovery timer and sets LR_SN to RSN if the t_loss_recovery timer is not running.

Meanwhile, when the RSN is not the largest SN among the SNs of the PDUs received so far (that is, when the RSN+1 value and the NEXT value are different), at least one PDU between LAST and RSN is not received. However, in this case, since the corresponding PDU cannot be received within a predetermined time, the PDCP layer sequentially delivers all stored PDCP SDUs having an SN smaller than the RSN to the upper layer (S310).

Thereafter, the PDCP layer delivers PDCP PDUs having consecutive SNs equal to or greater than the RSN among the stored PDCP PDUs to the upper layer as PDCP SDUs (S311), and the SN of the last PDCP SDU delivered to the upper layer is the LAST value. It is set to (S312). Then, the PDCP layer compares the LAST+1 value and the NEXT value (S313), and if the LAST+1 value is different from the NEXT value, if the t_loss_recovery timer is not running, it drives the t_loss_recovery timer and sets LR_SN to LAST+1 ( S314).

On the other hand, when it is determined in step S301 that the t_loss_recovery timer has expired, the corresponding PDU cannot be received within a predetermined time. Accordingly, the PDCP layer sets the LR_SN value to the RSN value (S309), and sequentially delivers all stored PDCP SDUs having an SN smaller than LR_SN to the upper layer (S310).

Then, the PDCP layer performs steps S311 to S314.

4 is a flowchart illustrating a method of processing downlink data of a terminal according to another embodiment of the present invention, illustrating a method of processing downlink data of a PDCP layer when an RLC layer of a terminal operates in an Acknowledged Mode (AM). will be. In FIG. 4, it is assumed that the PDCP layer of the terminal waits for reception of a missing PDCP SDU, and it is assumed that the SDU delivery timer t_sdu_delivery for delivering the SDU to the upper layer and the timer t_loss_recovery for loss recovery are in operation.

4, the PDCP layer of the UE determines whether t_sdu_delivery, a timer for SDU delivery, has expired (S401), and when the t_sdu_delivery timer has not expired, determines whether t_loss_recovery, a timer for loss recovery, has expired ( S402).

When the t_sdu_delivery timer has not expired and the t_loss_recovery timer has expired, the PDCP layer immediately transmits a PDCP status report to the transmitter so that the corresponding PDU can be retransmitted from the transmitter (S403). The PDCP status report may include SDU missing information.

On the other hand, if the PDCP layer receives a PDCP PDU whose SN is an RSN from a lower layer while the t_loss_recovery timer has not expired (S404), the PDCP PDU is not discarded after decoding and header restoration of the received PDCP PDU, The received PDCP SDU is stored in the PDCP buffer (S405).

The PDCP layer compares the SN (ie, RSN) of the received PDCP SDU with the NEXT value and sets the NEXT value to RSN+1 when the RSN is greater than or equal to the NEXT value (S406).

Thereafter, the PDCP layer determines whether the RSN is the same as the LAST+1 value, which is the SN of the PDU that finally delivered the SDU to the upper layer (S407).

As a result of determination in step S407, if the RSN is equal to the LAST+1 value, it means that the received SDUs are delivered in an orderly manner. Therefore, the PDCP layer checks whether the t_loss_recovery timer is operated, and when the t_loss_recovery timer is operated, the operation is canceled. In addition, the PDCP layer checks whether the t_sdu_delivery timer is running, and releases the t_sdu_delivery timer if it is running (S408).

Thereafter, the PDCP layer transmits PDCP PDUs having consecutive SNs having an SN greater than or equal to the RSN among the stored PDCP PDUs as PDCP SDUs to a higher layer (S414).

Then, the PDCP layer sets the SN of the last PDCP SDU delivered to the upper layer as the LAST value (S415).

Thereafter, the PDCP layer compares the LAST+1 value and the NEXT value (S416). Here, when the LAST+1 value is different from the NEXT value, it means that at least one PDU has not been received between LAST+1 and NEXT. In this case, since the corresponding PDU may be received within a certain time, the PDCP layer drives the t_loss_recovery timer if the t_loss_recovery timer is not running and sets LR_SN to LAST+1. In addition, the PDCP layer checks whether the t_sdu_delivery timer is running, drives the t_sdu_delivery timer if it is not running, and sets D_SN to the LAST+1 value (S417). Here, D_SN means the SN of the SDU to be delivered.

If it is determined in step S407 that the RSN is not equal to LAST+1, the PDCP layer compares the RSN+1 value and the NEXT value, and compares the LAST+1 value and the NEXT value (S409).

As a result of determination in step 409, if the LAST+1 value is different from the NEXT value, it means that at least one PDU has not been received between LAST+1 and NEXT. In this case, since the corresponding PDU can be received within a certain time, the PDCP layer drives the t_loss_recovery timer and sets LR_SN to LAST+1 if the t_loss_recovery timer is not running. Further, if the t_sdu_delivery timer is not running, the PDCP layer drives the t_sdu_delivery timer and sets D_SN to LAST+1 (S410).

Alternatively, when the RSN is the largest SN among the SNs of the PDUs received so far (that is, the RSN+1 value and the NEXT value are the same), it means that at least one PDU has not been received between the LAST and the RSN. In this case, too, since the corresponding PDU may be received within a certain time, the PDCP layer drives the t_loss_recovery timer if the t_loss_recovery timer is not running and sets the LR_SN to RSN. In addition, the PDCP layer drives the t_sdu_delivery timer if the t_sdu_delivery timer is not running, and sets D_SN to LAST+1.

Meanwhile, if the RSN is not the largest SN among the SNs of the PDUs received so far (i.e., the RSN+1 value and the NEXT value are different), at least one PDU between LAST and RSN is not received, so immediately The PDCP status report is transmitted so that the PDU can be retransmitted from the transmitting side (S411).

As a result of the determination in step S401, if the t_sdu_delivery timer has expired, it is difficult to receive the D_SN PDU. In this case, the PDCP layer sets the RSN to D_SN (S412), and sequentially delivers all stored PDCP SDUs having an SN smaller than D_SN to the upper layer (S413).

Thereafter, the PDCP layer delivers PDCP PDUs having consecutive SNs equal to or greater than the RSN among the stored PDCP PDUs to the upper layer as PDCP SDUs (S414), and the SN of the last PDCP SDU delivered to the upper layer is the LAST value. It is set to (S415). In addition, the PDCP layer compares the LAST+1 value and the NEXT value (S416), and if the LAST+1 value is different from the NEXT value, if the t_loss_recovery timer is not running, it drives the t_loss_recovery timer and sets LR_SN to LAST+1, If the t_sdu_delivery timer is not running, it is driven and D_SN is set to LAST+1 (S417).

Hereinafter, a method for efficient interworking between a cellular mobile communication network and a WiFi network and a method for receiving data by a terminal will be described.

5 is a conceptual diagram showing a general interworking structure between a cellular mobile communication network and a WiFi network.

Cellular mobile communication providers such as the LTE system use a method of offloading data over a WiFi network (or wireless LAN) in order to prepare for the explosion of mobile data. However, until now, as shown in FIG. 5, since the cellular mobile communication network and the WiFi network are interlocked in the core network, a seamless handover and quality of service (QoS) cannot be provided according to the movement of the terminal. There is.

That is, as shown in FIG. 5, an access point (AP) 501 of a WiFi network exists in an Evolved Packet Core (EPC) 510 of a Visited Public Land Mobile Network (VPLMN) Since it is connected to the evolved packet data gateway) 511 or connected to the PDN GW (Packet Data Network Gateway) 521 existing in the core network 520 of the HPLMN (Home PLMN), the terminal is connected to WiFi in the cellular mobile communication network. When moving to a network or moving between different access points in a WiFi network, there is a problem in that a processing delay occurs due to a handover, and the quality of service is deteriorated.

FIG. 6 is a conceptual diagram illustrating an interworking structure between a cellular mobile communication network and a WiFi network according to an embodiment of the present invention, and illustrates a network structure for efficiently distributing data from a cellular mobile communication network to a WiFi network.

As shown in FIG. 6, the present invention provides a structure for interworking between a cellular mobile communication network (eg, an LTE system) and a WiFi network at the level of a wireless access network. That is, in the present invention, the access point (AP) 601, 602 of the WiFi network is connected to the base station (eNB) 610 of the cellular mobile communication network, so that the access point 601, 602 of the WiFi network and the cellular mobile communication By allowing the base stations 610 of the network to interwork with each other at the level of the radio access network, it is possible to reduce the processing delay time during handover of the terminal, and to guarantee the quality of service through carrier aggregation between different radio access technologies (Inter-RAT). I can.

FIG. 7 is a conceptual diagram illustrating a data processing process of a terminal in an interworking structure between a cellular mobile communication network and a WiFi network as shown in FIG. 5, and shows a process of transferring data from a WiFi interface provided in the terminal to an upper layer. The WiFi interface provided in the terminal may be a WiFi Ethernet driver 701.

When the WiFi Ethernet driver 701 of the terminal receives the frame, it sees the protocol field among the Ethernet frame types in the header of the frame and performs demultiplexing to transmit the MAC SDU to the appropriate protocol entity. Deliver. For example, if the EtherType field of the frame header is 0x0800, this means an IP PDU, and the WiFi Ethernet driver 701 transfers data to the IP layer 702. The IP layer 702 transmits the IP SDU to the appropriate protocol entity by demultiplexing by looking at the protocol type field of the transmitted IP header. For example, the IP layer 702 may be assigned to an Internet Control Message Protocol (ICMP) 705, Internet Group Message Protocol (IGMP) 706, or Transport protocol 707 entity depending on the protocol type of the IP header. IP SDU can be delivered.

Alternatively, if the EtherType field is 0x0806, it is an Address Resolution Protocol (ARP) PDU, so the Ethernet driver 701 can transfer data to the ARP layer 703, and if the EtherType field is 0x8035, RARP ( Data can be delivered to the Reverse Address Resolution Protocol) layer 704.

FIG. 8 is a conceptual diagram illustrating a data processing process of a terminal in the structure of interworking a cellular mobile communication network and a WiFi network as shown in FIG. 6, and in a structure in which the cellular mobile communication network and the WiFi network are interlocked at the radio access network level, It shows the process of transferring data from the WiFi interface to the upper layer.

When the terminal's WiFi Ethernet driver 801 receives the frame, it sees the protocol field among the Ethernet frame types in the header of the received frame and performs demultiplexing to determine the MAC as an appropriate protocol entity. It delivers the SDU.

For example, when the type (EtherType) field is 0x0800, the Ethernet driver 801 can transfer data to the IP layer 811, and when the type (EtherType) field is 0x0806, the Ethernet driver 801 can transfer data to the ARP layer 812. And, when the type (EtherType) field is 0x8035, data may be delivered to the RARP layer 813. The IP layer 811 transmits the IP SDU to an appropriate protocol entity by demultiplexing by looking at the protocol type field of the transmitted IP header. For example, the IP layer 811 may deliver an IP SDU to the ICMP 814, User Datagram Protocol (UDP) 815, or Transport Control Protocol (TCP) 816 entity according to the protocol type of the IP header.

In addition, in the present invention, values representing PDCP, RLC, MAC, and PHY of the cellular mobile communication system are defined and used in values of the existing type (EtherType) protocol field. The newly defined type protocol field values are, for example, PDCP 802, RLC 803, MAC 804, PHY 805 of UMTS (Universal Mobile Telecommunication System), PDCP 805, and RLC of LTE system. Values representing 806 and MAC 807 may be defined. However, the technical idea of the present invention is not limited thereto, and the newly defined type protocol field value may be configured with various values according to the type of the interlocked cellular mobile communication system.

For example, if the received frame type (EtherType) protocol field is 0xXXXX and this value is defined as an LTE PDCP PDU, the Ethernet driver 801 demultiplexes the received frame and then transfers the received frame to the LTE PDCP 802 layer. Can pass data.

The present invention provides an interworking structure at the level of a wireless access network of a 3GPP network including LTE and a WiFi network through the above method, and carrier aggregation between different radio access technologies (Inter-RAT) such as a 3GPP network and a WiFi network. Through this, the access point (AP) of the WiFi network can be used like a small cell base station to increase the data transmission rate of the user, provide seamless handover, and guarantee quality of service.

Although described with reference to the above embodiments, those skilled in the art will understand that various modifications and changes can be made to the present invention without departing from the spirit and scope of the present invention described in the following claims. I will be able to.

110: macro base station 111: PDCP
112: RLC 113: MAC
120: small cell base station 121: PHY
130: macro base station 131: PDCP
132: RLC 140: small cell base station
141: MAC 142: PHY
150: macro base station 151: PDCP
160: small cell base station 161: RLC
162: MAC 163: PHY
170: macro base station 180: small cell base station
181: PDCP 182: RLC
183: MAC 184: PHY
510: EPC 511: ePDG
520: EPC 521: PDN GW
610: base station 601: AP
602: AP 701: Ethernet driver
702: IP 703: ARP
704: RARP 705: ICMP
706: IGMP 707: Transport Protocol
801: Ethernet driver 802: UMTS PDCP
803: UMTS RLC 804: UMTS MAC
805: LTE PDCP 806: LTE RLC
807: LTE MAC 811: IP
812: ARP 813: RARP
814: ICMP 815: UDP
817: TCP

Claims (14)

As a communication method of a terminal receiving downlink data,
Receiving, by a PDCP layer of the terminal, downlink data from a plurality of radio link control (RLC) layers;
Obtaining, by the PDCP layer, a plurality of protocol data units (PDUs) from the downlink data;
Rearranging, by the PDCP layer, the plurality of PDUs based on a comparison result of a sequence number of each of the plurality of PDUs and a sequence number of a PDU scheduled to be received by the PDCP layer;
Obtaining at least one SDU from the PDUs in which the PDCP layer is rearranged; And
Including the step of delivering the at least one SDU to an upper layer of the PDCP layer,
The plurality of RLC layers,
A communication method of a terminal comprising a first RLC layer connected to a first base station and a second RLC layer connected to a second base station. In claim 1,
The first RLC layer operates in an unacknowledged mode (UM),
The communication method of the terminal,
Further comprising driving a loss recovery timer, which is a timer for recovering data loss,
The step of delivering the at least one SDU to the upper layer,
The communication method of the terminal, characterized in that executed after the driving of the loss recovery timer is terminated. In claim 2,
The communication method of the terminal,
Terminal further comprising the step of terminating the driving of the loss recovery timer when the value obtained by adding 1 to the sequence number of the PDU last obtained by the PDCP layer of the terminal and the PDU sequence number obtained from the downlink data match. Method of communication. In claim 1,
The second RLC layer operates in an acknowledged mode (AM),
The communication method of the terminal,
Driving a loss recovery timer, which is a timer for recovering data loss; And
Driving an SDU delivery timer, which is a timer for transferring a service data unit (SDU) obtained from the downlink data to an upper layer of the PDCP layer,
The step of delivering the at least one SDU to the upper layer,
The communication method of the terminal, characterized in that executed after the driving of the loss recovery timer and the SDU delivery timer is terminated. According to claim 4,
The communication method of the terminal,
When the PDCP layer of the UE does not match the PDU sequence number of the downlink data with the value obtained by adding 1 to the sequence number of the PDU last acquired,
The communication method of the terminal further comprising the step of transmitting a PDCP status message including information on the loss of data. According to claim 4,
The communication method of the terminal,
When a value obtained by adding 1 to a sequence number of a PDU last acquired by the PDCP layer of the UE and a PDU sequence number of the downlink data match,
Terminating the driving of the loss recovery timer;
Terminating the driving of the SDU delivery timer; And
The communication method of the terminal further comprising the step of transmitting the at least one SDU to the upper layer. In claim 1,
After the step of obtaining the PDUs,
The communication method of the terminal further comprising the step of determining whether the obtained PDU is a PDU for radio link control (RLC) re-establishment. According to claim 7,
The communication method of the terminal,
If the acquired PDU is not a PDU for RLC reconfiguration,
The communication method of the terminal further comprising the step of sequentially transmitting the at least one SDU obtained from PDUs having a sequence number smaller than the sequence number of the obtained PDU to the upper layer. According to claim 7,
If the acquired PDU is a PDU for RLC reconfiguration,
Determining whether the obtained sequence number of the PDU and the sequence number of the last PDCP PDU delivered by the PDCP layer to a higher layer, plus 1, match. According to claim 9,
When the obtained sequence number of the PDU and the value obtained by adding 1 to the sequence number of the last PDCP PDU do not match,
The communication method of the terminal, characterized in that to withhold delivery of the at least one SDU obtained from the plurality of PDUs. According to claim 9,
When the obtained sequence number of the PDU and the value obtained by adding 1 to the sequence number of the last PDCP PDU match,
Transferring the acquired PDU and the at least one SDU acquired from PDUs having a sequence number and a sequence number of the acquired PDU to a higher layer; The communication method of the terminal further comprising a. A communication method of a terminal including a first communication protocol entity supporting a first communication protocol and a second communication protocol entity supporting a second communication protocol that is a protocol separate from the first communication protocol,
Receiving data by the first communication protocol entity from a base station;
Routing data in a packet data control protocol (PDCP) layer of the first communication protocol entity;
Generating a media access control (MAC) service data unit (SDU) by demultiplexing the data; And
And transmitting the MAC SDUs to the second communication protocol entity according to a value indicated by a protocol type field included in the data received by the first communication protocol entity. According to claim 12,
The first communication protocol is one of a long-term evolution (LTE) protocol and a universal mobile telecommunication system (UMTS) protocol, and the second communication protocol is a WiFi protocol. According to claim 12,
The protocol type field,
A communication method of a terminal, comprising an Ethernet frame type protocol field.

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