Patent Application
20190021069
The present invention relates to a wireless communication system and, more particularly, to a method and apparatus for transmitting/receiving data.
A wireless communication system has been widely deployed to provide a diverse range of communication services such as a voice communication service and a data communication service. Generally, the wireless communication system is a sort of multiple access system capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc.). For example, the multiple access system may include one of a code division multiple access (CDMA) system, a frequency division multiple access (FDMA) system, a time division multiple access (TDMA) system, an orthogonal frequency division multiple access (OFDMA) system, a single carrier frequency division multiple access (SC-FDMA) system, a multi-carrier frequency division multiple access (MC-FDMA) system, and the like.
With appearance and spread of machine-to-machine (M2M) communication and a variety of devices such as smartphones and tablet PCs and technology demanding a large amount of data transmission, data throughput needed in a cellular network has rapidly increased. To satisfy such rapidly increasing data throughput, carrier aggregation technology, cognitive radio technology, etc. for efficiently employing more frequency bands and multiple input multiple output (MIMO) technology, multi-base station (BS) cooperation technology, etc. for raising data capacity transmitted on limited frequency resources have been developed.
In addition, a communication environment has evolved into increasing density of nodes accessible by a user at the periphery of the nodes. A node refers to a fixed point capable of transmitting/receiving a radio signal to/from the UE through one or more antennas. A communication system including high-density nodes may provide a better communication service to the UE through cooperation between the nodes.
Due to introduction of new radio communication technology, the number of user equipments (UEs) to which a BS should provide a service in a prescribed resource region increases and the amount of data and control information that the BS should transmit to the UEs increases. Since the amount of resources available to the BS for communication with the UE(s) is limited, a new method in which the BS efficiently receives/transmits uplink/downlink data and/or uplink/downlink control information using the limited radio resources is needed.
With the development of smart devices, a new method for efficiently transmitting/receiving a small amount of data or infrequently occurring data is required.
The technical objects that can be achieved through the present invention are not limited to what has been particularly described hereinabove and other technical objects not described herein will be more clearly understood by persons skilled in the art from the following detailed description.
According to an aspect of the present invention, provided herein is a method of receiving data by a user equipment in a wireless communication system. The method may include receiving a paging message; if the paging message includes downlink data for the user equipment, transmitting a radio resource control (RRC) connection request message including acknowledgement information indicating an acknowledgement of the downlink data; and receiving an RRC connection reject message including information indicating that the acknowledgement information is confirmed.
In another aspect of the present invention, provided herein is a user equipment for receiving data in a wireless communication system. The user equipment may include a transceiver, and a processor configured to control the transceiver. The processor may be configured to: control the transceiver to receive a paging message; if the paging message includes downlink data for the user equipment, control the transceiver to transmit a radio resource control (RRC) connection request message including acknowledgement information indicating an acknowledgement of the downlink data; and control the transceiver to receive an RRC connection reject message including information indicating that the acknowledgement information is confirmed.
In another aspect of the present invention, provided herein is a method of transmitting data by a base station in a wireless communication system. The method may include transmitting a paging message for a user equipment; and receiving a radio resource control (RRC) connection request message from the user equipment. If the paging message includes downlink data for the user equipment and the RRC connection request message includes acknowledgement information indicating an acknowledgement of the downlink data, an RRC connection reject message including information indicating that the acknowledgement information is confirmed may be transmitted to the user equipment.
In another aspect of the present invention, provided herein is a base station for transmitting data in a wireless communication system. The base station may include a transceiver, and a processor configured to control the transceiver. The processor may be configured to: control the transceiver to transmit a paging message for a user equipment; and control the transceiver to receive a radio resource control (RRC) connection request message from the user equipment. If the paging message includes downlink data for the user equipment and the RRC connection request message includes acknowledgement information indicating an acknowledgement of the downlink data, the processor may be configured to control the transceiver to transmit an RRC connection reject message including information indicating that the acknowledgement information is confirmed to the user equipment.
In each aspect of the present invention, the downlink data may be transmitted or received in a non-access stratum (NAS) message in the paging message.
In each aspect of the present invention, an RRC layer of the user equipment may deliver paging information in the paging message and the downlink data to a non-access stratum (NAS) layer of the user equipment.
In each aspect of the present invention, upon receiving the RRC connection reject message, the user equipment may terminate an RRC connection establishment procedure started by transmission of the RRC connection request message.
In each aspect of the present invention, the downlink data may be transmitted or received through the paging message when the user equipment is in a discontinuous reception mode or a power saving mode.
In each aspect of the present invention, the paging message may further include information indicating that the downlink data is included in the paging message.
The above technical solutions are merely some parts of the embodiments of the present invention and various embodiments into which the technical features of the present invention are incorporated can be derived and understood by persons skilled in the art from the following detailed description of the present invention.
According to the present invention, uplink/downlink signals can be efficiently transmitted/received. Therefore, overall throughput of a radio communication system can be improved.
According to the present invention, a low-complexity/low-cost UE can communicate with the network while maintaining backward compatibility with the legacy system.
According to an embodiment of the present invention, it is possible to implement a low-complexity/low-cost UE.
According to an embodiment of the present invention, a UE can communicate with the network in narrowband.
According to an embodiment of the present invention, a small amount of data can be efficiently transmitted/received.
It will be appreciated by persons skilled in the art that that the effects that can be achieved through the present invention are not limited to what has been particularly described hereinabove and other advantages of the present invention will be more clearly understood from the following detailed description.
The accompanying drawings, which are included to provide a further understanding of the invention, illustrate embodiments of the invention and together with the description serve to explain the principle of the invention.
Although the terms used in the present invention are selected from generally known and used terms while considering functions of the present invention, they may vary according to intention or customs of those skilled in the art or emergence of new technology. Some of the terms mentioned in the description of the present invention may have been selected by the applicant at his or her discretion, and in such cases the detailed meanings thereof will be described in relevant parts of the description herein. Thus, the terms used in this specification should be interpreted based on the substantial meanings of the terms and the whole content of this specification rather than their simple names or meanings.
The embodiments of the present invention described hereinbelow are combinations of elements and features of the present invention. The elements or features may be considered selective unless mentioned otherwise. Each element or feature may be practiced without being combined with other elements or features. Further, an embodiment of the present invention may be constructed by combining parts of the elements and/or features. Operation orders described in embodiments of the present invention may be rearranged. Some constructions or features of any one embodiment may be included in another embodiment and may be replaced with corresponding constructions or features of another embodiment.
In the description of the attached drawings, a detailed description of known procedures or steps of the present invention will be avoided lest it should obscure the subject matter of the present invention. In addition, procedures or steps that could be understood to those skilled in the art will not be described either.
Throughout the specification, when a certain portion “includes” or “comprises” a certain component, this indicates that other components are not excluded and may be further included unless otherwise noted. The terms “unit”, “-or/er” and “module” described in the specification indicate a unit for processing at least one function or operation, which may be implemented by hardware, software or a combination thereof. In addition, the terms “a” (or “an”), “one”, “the”, etc. may include a singular representation and a plural representation in the context of the present invention (more particularly, in the context of the following claims) unless indicated otherwise in the specification or unless context clearly indicates otherwise.
The embodiments of the present invention can be supported by standard specifications disclosed for at least one of wireless access systems including an institute of electrical and electronics engineers (IEEE) 802.xx, a 3rd generation partnership project (3GPP) system, a 3GPP Long Term Evolution (3GPP LTE) system, and a 3GPP2 system. That is, steps or parts that are not described to clarify the technical features of the present invention may be explained with reference to the above standard specifications.
In addition, all terms set forth herein may be explained by the above standard specifications. For example, one or more of standard specifications, such as 3GPP TS 36.211, 3GPP TS 36.213, 3GPP TS 36.321, 3GPP TS 36.322, 3GPP TS 36.323, 3GPP TS 36.331, 3GPP TS 23.401, 3GPP TS 24.301, 3GPP TS 23.228, 3GPP TS 29.228, 3GPP TS 23. 218, 3GPP TS 22.011, and 3GPP TS 36.413 may be referenced.
Reference will now be made in detail to the embodiments of the present disclosure with reference to the accompanying drawings. The detailed description, which will be given below with reference to the accompanying drawings, is intended to explain exemplary embodiments of the present disclosure, rather than to show the only embodiments that can be implemented according to the invention.
Specific terms used for the embodiments of the present invention are provided to aid in understanding of the present invention. These specific terms may be replaced with other terms within the scope and spirit of the present invention.
The terms used in this specification are defined as follows.
The EPC is a core element of system architecture evolution (SAE) for improving performance of 3GPP technology. SAE corresponds to a research project for determining a network structure supporting mobility between various types of networks. For example, SAE aims to provide an optimized packet-based system for supporting various radio access technologies and providing an enhanced data transmission capability.
Specifically, the EPC is a core network of an IP mobile communication system for 3GPP LTE and can support real-time and non-real-time packet-based services. In conventional mobile communication systems (i.e. second-generation or third-generation mobile communication systems), functions of a core network are implemented through a circuit-switched (CS) sub-domain for voice and a packet-switched (PS) sub-domain for data. However, in a 3GPP LTE system which is evolved from the third generation communication system, CS and PS sub-domains are unified into one IP domain. That is, in 3GPP LTE, connection of terminals having IP capability can be established through an IP-based business station (e.g., an eNodeB (evolved Node B)), EPC, and an application domain (e.g., IMS). That is, the EPC is an essential structure for end-to-end IP services.
The EPC may include various components.
The SGW (or S-GW) operates as a boundary point between a radio access network (RAN) and a core network and maintains a data path between an eNodeB and the PDN GW. When. When a terminal moves over an area served by an eNodeB, the SGW functions as a local mobility anchor point. That is, packets. That is, packets may be routed through the SGW for mobility in an evolved UMTS terrestrial radio access network (E-UTRAN) defined after 3GPP release-8. In addition, the SGW may serve as an anchor point for mobility of another 3GPP network (a RAN defined before 3GPP release-8, e.g., UTRAN or GERAN (global system for mobile communication (GSM)/enhanced data rates for global evolution (EDGE) radio access network).
The PDN GW (or P-GW) corresponds to a termination point of a data interface for a packet data network. The PDN GW may support policy enforcement features, packet filtering and charging support. In addition, the PDN GW may serve as an anchor point for mobility management with a 3GPP network and a non-3GPP network (e.g., an unreliable network such as an interworking wireless local area network (I-WLAN) and a reliable network such as a code division multiple access (CDMA) or WiMax network.
Although the SGW and the PDN GW are configured as separate gateways in the example of the network structure of
The MME performs signaling and control functions for supporting access of a UE for network connection, network resource allocation, tracking, paging, roaming and handover. The MME controls control plane functions associated with subscriber and session management. The MME manages numerous eNodeBs and signaling for selection of a conventional gateway for handover to other 2G/3G networks. In addition, the MME performs security procedures, terminal-to-network session handling, idle terminal location management, etc.
The SGSN handles all packet data such as mobility management and authentication of a user for other 3GPP networks (e.g., a GPRS network).
The ePDG serves as a security node for a non-3GPP network (e.g., an I-WLAN, a Wi-Fi hotspot, etc.).
As described above with reference to
Additionally,
Among the reference points shown in
As shown in the figure, while radio resource control (RRC) connection is activated, an eNodeB may perform routing to a gateway, scheduling transmission of a paging message, scheduling and transmission of a broadcast channel (BCH), dynamic allocation of resources to a UE on uplink and downlink, configuration and provision of eNodeB measurement, radio bearer control, radio admission control, and connection mobility control. In the EPC, paging generation, LTE_IDLE state management, ciphering of the user plane, SAE bearer control, and ciphering and integrity protection of NAS signaling.
The radio interface protocol is based on the 3GPP wireless access network standard. The radio interface protocol horizontally includes a physical layer, a data link layer, and a networking layer. The radio interface protocol is divided into a user plane for transmission of data information and a control plane for delivering control signaling which are arranged vertically.
The protocol layers may be classified into a first layer (L1), a second layer (L2), and a third layer (L3) based on the three sublayers of the open system interconnection (OSI) model that is well known in the communication system.
Hereinafter, description will be given of a radio protocol in the control plane shown in
The physical layer, which is the first layer, provides an information transfer service using a physical channel. The physical channel layer is connected to a medium access control (MAC) layer, which is a higher layer of the physical layer, through a transport channel. Data is transferred between the physical layer and the MAC layer through the transport channel. Transfer of data between different physical layers, i.e., a physical layer of a transmitter and a physical layer of a receiver is performed through the physical channel.
The physical channel consists of a plurality of subframes in the time domain and a plurality of subcarriers in the frequency domain. One subframe consists of a plurality of symbols in the time domain and a plurality of subcarriers. One subframe consists of a plurality of resource blocks. One resource block consists of a plurality of symbols and a plurality of subcarriers. A Transmission Time Interval (TTI), a unit time for data transmission, is 1 ms, which corresponds to one subframe.
According to 3GPP LTE, the physical channels present in the physical layers of the transmitter and the receiver may be divided into data channels corresponding to Physical Downlink Shared Channel (PDSCH) and Physical Uplink Shared Channel (PUSCH) and control channels corresponding to Physical Downlink Control Channel (PDCCH), Physical Control Format Indicator Channel (PCFICH), Physical Hybrid-ARQ Indicator Channel (PHICH) and Physical Uplink Control Channel (PUCCH).
The second layer includes various layers. First, the MAC layer in the second layer serves to map various logical channels to various transport channels and also serves to map various logical channels to one transport channel. The MAC layer is connected with an RLC layer, which is a higher layer, through a logical channel. The logical channel is broadly divided into a control channel for transmission of information of the control plane and a traffic channel for transmission of information of the user plane according to the types of transmitted information.
The radio link control (RLC) layer in the second layer serves to segment and concatenate data received from a higher layer to adjust the size of data such that the size is suitable for a lower layer to transmit the data in a radio interface.
The Packet Data Convergence Protocol (PDCP) layer in the second layer performs a header compression function of reducing the size of an IP packet header which has a relatively large size and contains unnecessary control information, in order to efficiently transmit an IP packet such as an IPv4 or IPv6 packet in a radio interface having a narrow bandwidth. In addition, in LTE, the PDCP layer also performs a security function, which consists of ciphering for preventing a third party from monitoring data and integrity protection for preventing data manipulation by a third party.
The Radio Resource Control (RRC) layer, which is located at the uppermost part of the third layer, is defined only in the control plane, and serves to configure radio bearers (RBs) and control a logical channel, a transport channel, and a physical channel in relation to reconfiguration and release operations. The RB represents a service provided by the second layer to ensure data transfer between a UE and the E-UTRAN.
If an RRC connection is established between the RRC layer of the UE and the RRC layer of a wireless network, the UE is in the RRC Connected mode. Otherwise, the UE is in the RRC Idle mode.
Hereinafter, description will be given of the RRC state of the UE and an RRC connection method. The RRC state refers to a state in which the RRC of the UE is or is not logically connected with the RRC of the E-UTRAN. The RRC state of the UE having logical connection with the RRC of the E-UTRAN is referred to as an RRC_CONNECTED state. The RRC state of the UE which does not have logical connection with the RRC of the E-UTRAN is referred to as an RRC_IDLE state. A UE in the RRC_CONNECTED state has RRC connection, and thus the E-UTRAN may recognize presence of the UE in a cell unit. Accordingly, the UE may be efficiently controlled. On the other hand, the E-UTRAN cannot recognize presence of a UE which is in the RRC_IDLE state. The UE in the RRC_IDLE state is managed by a core network in a tracking area (TA) which is an area unit larger than the cell. That is, for the UE in the RRC_IDLE state, only presence or absence of the UE is recognized in an area unit larger than the cell. In order for the UE in the RRC_IDLE state to be provided with a usual mobile communication service such as a voice service and a data service, the UE should transition to the RRC_CONNECTED state. A TA is distinguished from another TA by a tracking area identity (TAI) thereof. A UE may configure the TAI through a tracking area code (TAC), which is information broadcast from a cell.
When the user initially turns on the UE, the UE searches for a proper cell first. Then, the UE establishes RRC connection in the cell and registers information thereabout in the core network. Thereafter, the UE stays in the RRC_IDLE state. When necessary, the UE staying in the RRC_IDLE state selects a cell (again) and checks system information or paging information. This operation is called camping on a cell. Only when the UE staying in the RRC_IDLE state needs to establish RRC connection, does the UE establish RRC connection with the RRC layer of the E-UTRAN through the RRC connection procedure and transition to the RRC_CONNECTED state. The UE staying in the RRC_IDLE state needs to establish RRC connection in many cases. For example, the cases may include an attempt of a user to make a phone call, an attempt to transmit data, or transmission of a response message after reception of a paging message from the E-UTRAN.
The non-access stratum (NAS) layer positioned over the RRC layer performs functions such as session management and mobility management.
Hereinafter, the NAS layer shown in
The ESM (Evolved Session Management) belonging to the NAS layer performs functions such as default bearer management and dedicated bearer management to control a UE to use a PS service from a network. The UE is assigned a default bearer resource by a specific packet data network (PDN) when the UE initially accesses the PDN. In this case, the network allocates an available IP to the UE to allow the UE to use a data service. The network also allocates QoS of a default bearer to the UE. LTE supports two kinds of bearers. One bearer is a bearer having characteristics of guaranteed bit rate (GBR) QoS for guaranteeing a specific bandwidth for transmission and reception of data, and the other bearer is a non-GBR bearer which has characteristics of best effort QoS without guaranteeing a bandwidth. The default bearer is assigned to a non-GBR bearer. The dedicated bearer may be assigned a bearer having QoS characteristics of GBR or non-GBR.
A bearer allocated to the UE by the network is referred to as an evolved packet service (EPS) bearer. When the EPS bearer is allocated to the UE, the network assigns one ID. This ID is called an EPS bearer ID. One EPS bearer has QoS characteristics of a maximum bit rate (MBR) and/or a guaranteed bit rate (GBR).
Referring to
Referring to
A description of the protocol stacks and interfaces illustrated in
The random access procedure is used for a UE to obtain UL synchronization with a base station or to be assigned a UL radio resource.
The UE receives a root index and a physical random access channel (PRACH) configuration index from an eNB. Each cell has 64 candidate random access preambles defined by a Zadoff-Chu (ZC) sequence. The root index is a logical index used for the UE to generate 64 candidate random access preambles.
Transmission of a random access preamble is limited to a specific time and frequency resources for each cell. The PRACH configuration index indicates a specific subframe and preamble format in which transmission of the random access preamble is possible.
The random access procedure, in particular, a contention-based random access procedure, includes the following three steps. Messages transmitted in the following steps 1, 2, and 3 are referred to as msg1, msg2, and msg4, respectively.
As shown in
A UE in the connected state has RRC connection, and thus the E-UTRAN may recognize presence of the UE in a cell unit. Accordingly, the UE may be efficiently controlled. On the other hand, the eNB cannot recognize presence of a UE which is in the idle state. The UE in the idle state is managed by the core network in a tracking area unit which is an area unit larger than the cell. The tracking area is a unit of a set of cells. That is, for the UE which is in the idle state, only presence or absence of the UE is recognized in a larger area unit. In order for the UE in the idle state to be provided with a usual mobile communication service such as a voice service and a data service, the UE should transition to the connected state.
When the user initially turns on the UE, the UE searches for a proper cell first, and then stays in the idle state. Only when the UE staying in the idle state needs to establish RRC connection, does the UE establish RRC connection with the RRC layer of the eNB through the RRC connection procedure and then transition to the RRC connected state.
The UE staying in the idle state needs to establish RRC connection in many cases. For example, the cases may include an attempt of a user to make a phone call, an attempt to transmit data, or transmission of a response message after reception of a paging message from the E-UTRAN.
In order for the UE in the idle state to establish RRC connection with the eNodeB, the RRC connection procedure needs to be performed as described above. The RRC connection procedure is broadly divided into transmission of an RRC connection request message from the UE to the eNB, transmission of an RRC connection setup message from the eNB to the UE, and transmission of an RRC connection setup complete message from the UE to eNB, which are described in detail below with reference to
Only when the UE successfully transmits the RRC connection setup complete message, does the UE establish RRC connection with the eNB and transition to the RRC connected mode.
In order for the UE of an idle state to transition to an activation state in which traffic transmission/reception can be performed due to occurrence of new traffic, a service request procedure is performed. If traffic to be transmitted by the UE occurs or traffic to be transmitted to the UE by a network occurs in a state in which the UE is registered with the network but an S1 connection is released and a wireless resource is not allocated to the UE due to traffic inactivation, i.e., in a state in which the UE is in an EMM registered state (EMM-Registered) but is in an ECM-Idle state, the UE requests that the network provide a service. Upon successfully completing the service request process, the UE transitions to an ECM connected state (ECM-Connected) and configures an ECM connection (RRC connection+S1 signaling connection) in a control plane and an E-RAB (a data radio bearer (DRB) and an S1 bearer) in a user plane, thereby transmitting/receiving traffic. If the network desires to transfer traffic to the UE of an ECM idle state (ECM-Idle), the network informs the UE, through a paging message, that there is traffic to be transmitted so that the UE may request that the network provide a service.
For a detailed network triggered service request procedure according to
In step 5 of the procedure of
If traffic to be transmitted occurs, the UE transmits an RRC connection request to the eNB through a random access procedure including steps 1) to 3) of
For details of the UE triggered service request procedure according to
Recently, machine type communication (MTC) has come to the fore as a significant communication standard issue. MTC refers to exchange of information between a machine and an eNB without involving persons or with minimal human intervention. For example, MTC may be used for data communication for measurement/sensing/reporting such as meter reading, water level measurement, use of a surveillance camera, inventory reporting of a vending machine, etc. and may also be used for automatic application or firmware update processes for a plurality of UEs. In MTC, the amount of transmission data is small and UL/DL data transmission or reception (hereinafter, transmission/reception) occurs occasionally. In consideration of such properties of MTC, it would be better in terms of efficiency to reduce production cost and battery consumption of UEs for MTC (hereinafter, MTC UEs) according to data transmission rate. Since the MTC UE has low mobility, the channel environment thereof remains substantially the same. If an MTC UE is used for metering, reading of a meter, surveillance, and the like, the MTC UE is very likely to be located in a place such as a basement, a warehouse, and mountain regions which the coverage of a typical eNB does not reach. In consideration of the purposes of the MTC UE, it is better for a signal for the MTC UE to have wider coverage than the signal for the conventional UE (hereinafter, a legacy UE).
It is expected that a number of devices will be wirelessly connected to each other through the Internet of Things (IoT). The IoT means internetworking of physical devices, connected devices, smart devices, buildings, and other items with electronics, software, sensors, actuators, and network connectivity that enable these objects to collect and exchange data. In other words, the IoT refers to a network of physical objects, machines, people, and other devices that enable connectivity and communication for the purpose of exchanging data for intelligent applications and services. The IoT allows objects to be sensed and controlled remotely through existing network infrastructures, thereby providing opportunities for the direct integration between the physical and digital worlds, which result in improving efficiency, accuracy and economic benefits. Particularly, in the present invention, the IoT using the 3GPP technology is referred to as cellular IoT (CIoT). In addition, the CIoT that transmits/receives IoT signals using a narrowband (e.g., a frequency band of about 200 kHz) is called NB-IoT.
The CIoT is used to monitor traffic transmitted over a relatively long period, e.g., from a few decades to a year (e.g., smoke alarm detection, power failure notification from smart meters, tamper notification, smart utility (gas/water/electricity) metering reports, software patches/updates, etc.) and support ‘IoT’ devices characterized as ultra-low complexity, power limitation and low data rates.
In the prior art, a connection with the network should be established for transmitting data to a UE in an EMM-Idle mode. To this end, the UE should successfully complete the service request procedure illustrated in
The User Plane CIoT EPS optimization and Control Plane CIoT optimization can be referred to U-plane CIoT EPS optimization and C-plane CIoT EPS optimization, respectively.
In the case of a Control Plane CIoT EPS optimization solution, there is no setup data radio bearer, but data packets are transmitted through signaling radio bearers. Thus, this solution is most suitable for transmission of infrequent small data packets. When a UE and MME use the Control Plane CIoT EPS optimization, the UE and MME may transfer IP or non-IP data through NAS signaling depending on data types selected for a PDN connection supported at PDN connection establishment. The Control Plane CIoT EPS optimization can be achieved by using NAS transport capabilities of RRC and S1-AP protocols and data transfer through GTP (Evolved General Packet Radio Service (GPRS) Tunneling Protocol) tunnels between an MME and an S-GW and between an S-GW and a P-GW.
An MME detects that the UE is in a power saving state (e.g. Power Saving Mode) and cannot be reached by paging at the moment, shall invoke extended buffering depending on operator configuration, except for cases described in next paragraphs. MME derives the expected time before radio bearers can be established to the UE. The MME then indicates DL Buffering Requested to the S-GW in the Downlink Data Notification Ack message and includes a DL Buffering Duration time and optionally a DL Buffering Suggested Packet Count. The MME stores a new value for the DL Data Buffer Expiration Time in the mobility management (MM) context for the UE based on the DL Buffering Duration time and skips the remaining steps of this procedure. The DL Data Buffer Expiration Time is used for UEs using power saving state and indicates that there are buffered data in the S-GW and that the user plane setup procedure is needed when the UE makes signalling with the network. When the DL Data Buffer Expiration Time has expired, the MME considers no DL data to be buffered and no indications of Buffered DL Data Waiting are sent during context transfers at tracking area update (TAU) procedures.
If there is an “Availability after DDN Failure” monitoring event configured for the UE in the MME, the MME/SGSN does not invoke extended buffering. Instead, the MME sets the Notify-on-available-after-DDN-failure flag to remember to send an “Availability after DDN Failure” notification when the UE becomes available. If there is a “UE Reachability” monitoring event configured for the UE in the MME, the MME/SGSN does not invoke extended buffering.
NOTE: When “Availability after DDN failure” and “UE reachability” monitoring events are used for a UE, the application server is assumed to send data when the UE is reachable, hence no extended buffering is needed. If there are multiple application servers, the event notifications and extended buffering may be needed simultaneously. It is assumed this is handled through additional information based on SLA as described in the next paragraph.
The MME may use additional information based on a SLA with the MTC user for when to invoke extended buffering, e.g. only invoke it for a certain APN, do not invoke it for certain subscribers, invoke extended buffering in conjunction with “Availability after DDN failure” and “UE reachability” monitoring events, etc.
A S-GW that receives a DL Buffering Requested indication in a Downlink Data Notification Ack message stores a new value for the DL Data Buffer Expiration Time based on the DL Buffering Duration time and does not send any additional Downlink Data Notification if subsequent downlink data packets are received in the S-GW before the buffer time DL Data Buffer Expiration Time has expired for the UE.
If the S-GW, while waiting for the user plane to be established, is triggered to send a second Downlink Data Notification for a bearer with higher priority (i.e. ARP priority level) than the first Downlink Data Notification was sent for, the S-GW sends a new Downlink Data Notification message indicating the higher priority to the MME. If the S-GW receives additional downlink data packets for a bearer with same or lower priority than the first Downlink Data Notification was sent for or if the S-GW has sent the second Downlink Data Notification message indicating the higher priority and receives additional downlink data packets for this UE, the S-GW buffers these downlink data packets and does not send a new Downlink Data Notification.
If the S-GW, while waiting for the user plane to be established, receives a Modify Bearer Request message from MME other than the one it sent a Downlink Data Notification message to, the S-GW re-sends the Downlink Data Notification message only to the new MME from which it received the Modify Bearer Request message.
Upon reception of a Downlink Data Notification Ack message with an indication that the Downlink Data Notification message has been temporarily rejected and if the Downlink Data Notification is triggered by the arrival of downlink data packets at the S-GW, the S-GW may start a locally configured guard timer and buffers all downlink user packets received to the given UE and waits for a Modify Bearer Request message to come. Upon reception of a Modify Bearer Request message, the S-GW re-sends the Downlink Data Notification message only to the new MME from which it received the Modify Bearer Request message. Otherwise the S-GW releases buffered downlink user packets at expiry of the guard timer or receiving the Delete Session Request message from MME.
Paging priority indication is included only if the MME receives a Downlink Data Notification with an ARP priority level associated with priority services, as configured by the operator.
One Paging Priority level can be used for multiple ARP priority level values. The mapping of ARP priority level values to Paging Priority level (or levels) is configured by operator policy.
During a congestion situation the eNB may prioritise the paging of UEs according to the Paging Priority indications.
If the MME, while waiting for a UE response to the Paging Request message sent without Paging Priority indication, receives a Downlink Data Notification which indicates an ARP priority level associated with priority services, as configured by the operator, the MME shall send another paging message with the suitable Paging Priority.
Paging strategies may be configured in the MME. Paging strategies may include:
NOTE: The Paging priority in the Paging message is set based on priority level of the ARP IE received in Downlink Data Notification or Create/Update Bearer Request message and is independent from any paging strategy.
The MME and the NB-IOT RAN may support further paging optimisations in order to reduce the signalling load and the network resources used to successfully page a UE by one or several following means:
When implementing such optimisations/strategies, the MME shall take into account any PSM active timer and the DRX interval for the UE.
If the UE Radio Capability for Paging Information is available in the MME, the MME adds the UE Radio Capability for Paging Information in the S1 Paging message to the eNB.
If the Information On Recommended Cells and eNBs For Paging is available in the MME, the MME shall take that information into account to determine the eNBs for paging and, when paging an eNB, the MME may transparently convey the information on recommended cells to the eNB.
The MME may include in the S1AP Paging message(s) the paging attempt count information. The paging attempt count information shall be the same for all eNBs selected by the MME for paging.
If the MME receives no response from the UE after this paging repetition procedure, it shall use the Downlink Data Notification Reject message to notify the S-GW about the paging failure, unless the MME is aware of an ongoing MM procedure that prevents the UE from responding, i.e. the MME received a Context Request message indicating that the UE performs TAU with another MME. When a Downlink Data Notification Reject message is received, the S-GW deletes the buffered packet(s). The S-GW may invoke the procedure P-GW Pause of Charging if UE is in ECM IDLE and the P-GW has enabled “PDN charging pause” feature.
NOTE: The S-GW may initiate the procedure P-GW Pause of Charging at any time before step 5 if the UE is in ECM IDLE and the P-GW has indicated that the feature is enabled for this PDN.
NOTE: if the RAT currently used is NB-IOT this shall be reported as different from E-UTRA.
If the Modify Bearer Request message is not sent because of above reasons and the P-GW charging is paused, then the S-GW shall send a Modify Bearer Request message with PDN Charging Pause Stop Indication to inform the P-GW that the charging is no longer paused. Other IEs are not included in this message.
Referring to
A CIoT network or technology refers to providing an optimized communication service to an IoT UE mainly in terms of a core network and a narrowband Internet of things (NB-IoT) network or technology refers to optimizing a radio interface of a legacy LTE technology for IoT.
As known by the name of NB-IoT, NB-IoT is radio technology for providing an IoT service using a narrowband frequency of about 200 kHz. As compared with the legacy LTE technology using a frequency band of a minimum of 1.25 MHz, NB-IoT uses a significantly narrow frequency band. Therefore, processing power can be minimized and power consumption can be minimized in terms of the UE.
CIoT is technology for minimizing power consumption of the UE through a scheme (C-plane solution) in which an MME processes data or a scheme (U-plane solution) in which the UE and the eNB maintain a context and use the context for the next connection even when the UE is in a state similar to an RRC_IDLE state, in order to solve waste of power of the UE caused by exchange of numerous messages in a legacy attach procedure or service request procedure (refer to
Therefore, NB-IoT radio technology and CIoT technology are individually applicable. That is, even when the NB-IoT radio technology is not used, it is possible to apply the CIoT technology through a legacy LTE radio network. This means that the CIoT technology is applicable to a UE incapable of using the NB-IoT radio technology, for example, a UE which has already been released by applying only the LTE radio technology. This also means that a cell based on the legacy LTE radio technology may support a legacy LTE UE such as a smartphone and simultaneously support an IoT UE.
A power saving mode (PSM) or extended discontinuous reception (eDRX) is under consideration. If traffic is queued for a UE, a normal LTE paging cycle during which the UE can be contacted by a network is 1.28 s. eDRX extends a cycle during which the UE may be in an idle state to more than 1.28 s. Accordingly, when there is no need to frequently awake, as in the case of an MTC UE, eDRX may be applied to reduce battery consumption. The PSM is a mode in which the UE informs the network that the UE will enter an indefinitely dormant state. At a predefined time or if data to be transmitted is present, the UE in the PSM wakes up and transmits data to the network, and remains in an idle state during a predetermined time so that the UE is reachable if needed. Since the UE is dormant during the entire PSM window, power consumption of the UE is extremely low.
In a legacy system prior to introduction of the PSM or eDRX, if an S1-U is in an idle state, the S-GW transmits a downlink data notification (DDN) message to an MME while buffering a downlink packet and the MME that has received the DDN message transmits a paging message to eNB(s). The UE that has received the paging message starts to perform a service request procedure. As the PSM or eDRX, which is a state in which the UE cannot be reachable even though the UE is in an idle state, i.e., a state in which the UE cannot respond even though the network transmits the paging message, is introduced, a situation may occur in which an S-GW has received downlink data but transmission of the DDN message is invalid. Therefore, in some cases, the S-GW needs to perform buffering for a longer period than in the legacy system.
Accordingly, a more efficient method capable of transmitting downlink data to the UE which is using the PSM or eDRX mode is demanded.
The present invention relates to a method of effectively delivering data transmitted to the UE from a server or the Internet. According to the present invention described hereinbelow, for delivery of data arriving at a network on downlink for the UE to the UE, connection between the network and the UE may be rapidly configured through minimum signaling between the UE and the network and the downlink data may be rapidly delivered to the UE through connection between the UE and the network. According to the present invention, the downlink data is delivered through a paging message to the UE which is using the eDRX mode or PSM for optimizing power consumption so that the downlink data can be rapidly delivered to the UE.
Proposals of the present invention may be applied to the UE which is using optimization of power consumption or requires optimization of power consumption. For example, the present invention may be used in a communication system supporting data transmission/reception of an IoT UE which uses CIoT and/or NB-IoT.
As illustrated in
Therefore, the present invention proposes a method of rapidly delivering data to the UE with minimum latency through minimum signaling when a data packet of a terminating call occurs.
Referring to
The MME may include the data packet to which the security and/or header compression protocol is applied in a general NAS message and transmit the NAS message. For example, the MME may use a NAS message configured to transmit the data packet, for example, a downlink general NAS transport message or a NAS message having a purpose equivalent to the downlink general NAS transport message, for delivery of the data packet for the UE.
Upon sending the paging message to the eNB, the MME may inform the eNB of whether the paging message additionally includes the data packet which should be delivered to a paged UE.
When the paging message that the MME sends to the eNB additionally includes the data packet which is to be delivered to the paged UE, the MME may transmit information about whether (the ciphering and/or integrity protection or) the header compression protocol has been applied to the data packet, upon sending the paging message.
In Step 3, when the paging message that the MME sends to the eNB additionally includes the data packet which is to be delivered to the paged UE, the MME may send, to the eNB, information as to whether the eNB is allowed to transmit the packet data when the paging message is sent to the UE in each cell for the data packet.
When the paging message that the MME transmits to the eNB additionally includes the data packet which is to be delivered to the paged UE, the MME may transmit, to the eNB, information as to whether the eNB should send the data packet after additionally applying the security or header compression protocol when the eNB sends the data packet to the paged UE.
When the paging message that the MME transmits to the eNB additionally includes the data packet which is to be delivered to the paged UE, the MME may transmit, to the eNB, information as to whether the eNB should send the data packet using a signaling radio bearer (SRB) when the eNB sends the data packet to the paged UE. That is, the MME may transmit, to the eNB, information as to whether or not the eNB should send the data packet through an RRC message or a NAS message.
If the MME informs the eNB that the data packet which should be delivered to the paged UE is present, the eNB may include the data packet in a paging message that the eNB transmits to the UE and include, in the paging message, information indicating that the data packet for the UE is present.
If the MME informs the eNB that the MME has applied the security (ciphering and/or integrity protection) or header compression protocol to the data packet that should be delivered to the paged UE, the eNB may include the data packet in the paging message that the eNB transmits to the UE and include, in the paging message, the information indicating that the data packet for the UE is present.
If the data packet that should be delivered to the UE is included in the paging message received by the eNB from the MME and the MME informs the eNB that eNB should send the data packet when the paging message is transmitted to the UE in each cell, the eNB may include the data packet in the paging message that the eNB transmits to the UE and include, in the paging message, the information indicating that the data packet for the UE is present.
If the data packet that should be delivered to the UE is included in the paging message received by the eNB from the MME and the MME informs the eNB that the data packet may be transmitted without additionally applying the security or header compression protocol, the eNB may include the data packet in the paging message that the eNB transmits to the UE and include, in the paging message, the information indicating that the data packet for the UE is present.
If the data packet that should be delivered to the UE is included in the paging message received by the eNB from the MME and the MME informs the eNB that the SRB should be used when the eNB transmits the data packet to the paged UE, the eNB may include the data packet in the paging message that the eNB transmits to the UE and include, in the paging message, the information indicating that the data packet for the UE is present.
In Step 4, the data packet may be included in an RRC message (e.g., downlink NAS transport message) used to transmit a NAS message in an RRC layer and then may be transmitted. Alternatively, the structure of an RRC paging message may be changed so that a container, which is used to transmit the NAS message, such as a NAS container may be included in the RRC paging message and a field indicating whether the container is included may be additionally included in the RRC paging message.
In Step 9, the data packet delivered to the NAS layer from the RRC layer may conform to a NAS PDU or message structure. For example, the UE may perform decoding on the assumption that the data packet received from the RRC layer is the NAS message.
For the UE to inform the network that the NAS message or the data packet included in the NAS message has been successfully received, the NAS layer of the UE may perform the following procedures after Step 9.
The NAS layer may perform a network initiated service request procedure.
The NAS layer may simply make the RRC layer establish an RRC connection. For example, if the data packet is delivered to the NAS layer of the UE together with the paging, the NAS layer may request that the RRC layer send a paging acknowledge in order to inform the network that the data packet and the paging have been successfully received. The RRC layer which is requested to send the paging acknowledgement may perform an RRC connection establishment procedure and set an establishment cause value as a paging response or the paging acknowledgement. The eNB may check whether the establishment cause value in an RRC connection establishment request message received from the UE is set as the paging response or the paging acknowledgement. For the RRC connection establishment request message of which establishment cause is set as the paging response or the paging acknowledgement, the eNB may additionally check an ID included in the RRC message. If the ID included in the RRC message is included in a paging message that the eNB has previously transmitted to each cell and if the eNB includes the data packet for the UE in the paging message, the eNB notifies the MME that paging and data delivery have been successfully performed. If the UE does not make any further request, for example, if the UE informs the eNB that there is no additional data to be transmitted, the eNB transmits an RRC connection reject message to the UE. In this case, the eNB may set a cause value in the RRC connection reject message as a value indicating paging acknowledge has been confirmed. Upon receiving the value indicating that paging acknowledge has been confirmed together with the RRC connection reject message for the RRC connection establishment request message that the UE has transmitted, the UE considers that the paging acknowledgement that the UE has transmitted has been successfully transmitted to the network and does not start the RRC connection establishment procedure unless other reasons for establishing a connection are present. That is, upon receiving the value indicating paging acknowledge has been confirmed together with the RRC connection reject message for the RRC connection establishment request message that the UE has transmitted, the UE may terminate the RRC connection establishment procedure unless other reasons for completing an RRC connection establishment are present. Conventionally, upon receiving an RRC connection message for the RRC connection establishment request message, the UE starts a timer and, if a predetermined time elapses, the UE again starts the RRC connection establishment procedure. However, according to the present invention, the UE does not attempt to automatically perform the RRC connection establishment procedure using the timer even though the UE receives the RRC connection rejection message. If the RRC connection establishment procedure is needed for other reasons, the UE may start the RRC connection establishment procedure. Accordingly, if the eNB sets a cause value as a value indicating that the paging response of the UE has been received and transmits the RRC connection reject message to the UE, the UE may maintain an RRC connection release state unless other reasons are present.
The NAS layer may start a process of transmitting a service request message in order to transmit an acknowledgement for the paging and the data packet. The NAS layer may set a cause value in a NAS message as a value indicating that the paging and the data have been received, and transmit the NAS message. The service request message may be submitted to the RRC layer and the RRC layer may perform the RRC connection establishment procedure. Through the RRC connection establishment procedure, the NAS service request message may be transmitted to the MME and the MME may be aware of whether downlink data has been successfully transmitted by receiving the NAS service request message.
In the step (e.g., Step 8) of
Meanwhile, in a general IoT system, a response should be transmitted to an entity that has transmitted the data packet in some cases but the response need not be transmitted in other cases. In consideration of this viewpoint, it may be unnecessary for the UE to transmit a response to the received downlink data at every time. Therefore, the MME or the eNB may provide the UE with information as to whether the UE should transmit an acknowledgement to the MME or the eNB. The UE may be configured such that the UE performs the above-described acknowledgement procedure only when this information indicates that the acknowledgement should be transmitted. Such indication information may be included in the NAS message that the MME transmits to the UE.
Conventionally, the UE sets a cause of the RRC connection request message as a mobile originated service request message or a mobile terminated service request and transmits the RRC connection request message. Meanwhile, according to the present invention, the UE may set the cause of the RRC connection request message as a paging response and transmit the RRC connection request message without the NAS message (i.e., without carrying the NAS message in the container of the RRC connection request message). As in the above-described proposal of the present invention, if the UE transmits the paging response through the RRC connection request message, there is no need to unnecessarily establish a NAS connection between the UE and the network. Therefore, the RRC connection request message including the above-described acknowledgement of the paging and the data packet may serve to inform the eNB that there is no need to establish a connection with the MME.
Conventionally, the RRC layer recognizes the paging and informs the NAS layer of the paging. The NAS layer which is informed by the RRC layer that there is paging transmits a service request and the RRC layer transfers a NAS message corresponding to the service request in a container of the RRC message. In other words, conventionally, the NAS message is transmitted after an RRC connection is established, whereas, according to the present invention, an RRC connection procedure may be ended after only the RRC connection is established. According to the Control Plane CIoT EPS optimization procedure (e.g., refer to
The UE 100 according to the present invention may include a transceiver 110, a processor 120, and a memory 130. The transceiver 110 may be referred to as a radio frequency (RF) unit. The transceiver 110 may be configured to transmit and receive various signals, data and information to and from an external device. The UE 100 may be connected to the storage device by wire and/or wirelessly. The processor 150 may control overall operation of the UE 100, and be configured to calculate and process information for the UE 100 to transmit and receive to and from the external device. In addition, the processor 120 may be configured to perform the proposed operations of the UE. The memory 130 may store the calculated and processed information for a predetermined time, and may be replaced by another constituent such as a buffer (not shown).
Referring to
For configuration of the UE 100 and the network apparatus, the details described in various embodiments of the present invention may be independently applied or implemented such that two or more embodiments are simultaneously applied. For simplicity, redundant description is omitted.
The embodiments of the present invention may be implemented through various means. For example, the embodiments may be implemented by hardware, firmware, software, or a combination thereof.
When implemented by hardware, a method according to embodiments of the present invention may be embodied as one or more application specific integrated circuits (ASICs), one or more digital signal processors (DSPs), one or more digital signal processing devices (DSPDs), one or more programmable logic devices (PLDs), one or more field programmable gate arrays (FPGAs), a processor, a controller, a microcontroller, a microprocessor, etc.
When implemented by firmware or software, a method according to embodiments of the present invention may be embodied as an apparatus, a procedure, or a function that performs the functions or operations described above. Software code may be stored in a memory unit and executed by a processor. The memory unit is located at the interior or exterior of the processor and may transmit and receive data to and from the processor via various known means.
As described above, the detailed description of the preferred embodiments of the present invention has been given to enable those skilled in the art to implement and practice the invention. Although the invention has been described with reference to exemplary embodiments, those skilled in the art will appreciate that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention described in the appended claims. Accordingly, the invention should not be limited to the specific embodiments described herein, but should be accorded the broadest scope consistent with the principles and novel features disclosed herein.
The communication method described above is applicable to various wireless communication systems including IEEE 802.16x and 802.11x systems as well as a 3GPP system. Furthermore, the proposed method is applicable to a millimeter wave (mmWave) communication system using an ultrahigh frequency band.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/KR2017/000739 | 1/20/2017 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62281198 | Jan 2016 | US |
