U.S. patent application number 14/426908 was filed with the patent office on 2015-08-20 for tracking area update method and user equipment.
This patent application is currently assigned to LG ELECTRONICS INC.. The applicant listed for this patent is LG ELECTRONICS INC.. Invention is credited to Hyunsook Kim, Jaehyun Kim, Laeyoung Kim, Taehyeon Kim.
Application Number | 20150237592 14/426908 |
Document ID | / |
Family ID | 50477641 |
Filed Date | 2015-08-20 |
United States Patent
Application |
20150237592 |
Kind Code |
A1 |
Kim; Hyunsook ; et
al. |
August 20, 2015 |
TRACKING AREA UPDATE METHOD AND USER EQUIPMENT
Abstract
The present specification provides a method for performing a
tracking area update (TAU) on user equipment. The method may
comprise the steps of: sending a TAU request message to a target
base station as user equipment moves from a source base station to
the target base station; performing a service request procedure or
a radio resource control (RRC) connection procedure shortly after
receiving, from the target base station, information related to
downlink data and/or information related to paging; and receiving a
paging signal from the target base station after performing the
procedure.
Inventors: |
Kim; Hyunsook; (Seoul,
KR) ; Kim; Jaehyun; (Seoul, KR) ; Kim;
Laeyoung; (Seoul, KR) ; Kim; Taehyeon; (Seoul,
KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LG ELECTRONICS INC. |
Seoul |
|
KR |
|
|
Assignee: |
LG ELECTRONICS INC.
Seoul
KR
|
Family ID: |
50477641 |
Appl. No.: |
14/426908 |
Filed: |
October 10, 2013 |
PCT Filed: |
October 10, 2013 |
PCT NO: |
PCT/KR2013/009064 |
371 Date: |
March 9, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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61711747 |
Oct 10, 2012 |
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61862091 |
Aug 5, 2013 |
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61869069 |
Aug 23, 2013 |
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61869761 |
Aug 25, 2013 |
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Current U.S.
Class: |
455/435.1 |
Current CPC
Class: |
H04W 68/02 20130101;
H04W 88/08 20130101; H04W 68/005 20130101; H04W 36/0011 20130101;
H04W 72/042 20130101; H04W 8/08 20130101; H04W 76/11 20180201; H04W
60/04 20130101 |
International
Class: |
H04W 60/04 20060101
H04W060/04; H04W 8/08 20060101 H04W008/08; H04W 68/02 20060101
H04W068/02; H04W 36/00 20060101 H04W036/00 |
Claims
1. A method of performing tracking area update (TAU) by a user
equipment (UE), the method comprising: transmitting a TAU request
message to a target base station as the UE moves from a source base
station to the target base station; performing a service request
procedure or an RRC (Radio Resource Control) connection procedure
immediately after receiving one or more of information regarding
downlink data and information regarding paging from the target base
station; and receiving a paging signal from the target base station
after the procedure.
2. The method of claim 1, wherein the information regarding paging
includes one or more of: information indicating that a service
request should be performed in response to the paging; information
regarding which one of a service request message and an extended
service request message should be transmitted in response to the
paging; and information indicating which one of a bearer setup
procedure for a CS (Circuit Switch) call and a bearer setup
procedure for a PS (Packet Switch) call is needed.
3. The method of claim 1, wherein the one or more information is
received through a TAU accept message or an NAS (Non Access
Stratum)-based message.
4. The method of claim 1, wherein the service request procedure
includes transmitting an NAS-based service request message.
5. The method of claim 1, wherein the RRC connection procedure
includes: receiving an RRC connection reconfiguration message from
the target base station; and transmitting an RRC connection
reconfiguration complete message to the target base station in
response to the reception of the RRC connection reconfiguration
message.
6. The method of claim 1, wherein the RRC connection procedure
includes: receiving an RRC-based radio bearer setup message from
the target base station; and transmitting an RRC-based radio bearer
setup complete message to the target base station in response to
the reception of the RRC-based radio bearer setup message.
7. The method of claim 1, wherein the RRC connection procedure
includes: transmitting an RRC connection request message to the
target base station; receiving an RRC connection setup message from
the target base station; and transmitting an RRC connection setup
complete message in response to the reception of the RRC connection
setup message.
8. A method of transferring downlink data for a user equipment from
a network node, the method comprising: when receiving downlink
supposed to be transferred to the UE, transmitting a downlink data
notification to a mobility management server for the UE; receiving
a request for processing the downlink data from the mobility
management server; maintaining buffering without deleting the
downlink data in response to the request; and retransmitting the
downlink data notification to a new mobility management server for
the UE.
9. The method of claim 8, further comprising receiving a bearer
modification request message from the new mobility management
server, wherein retransmitting the notification is performed after
receiving the bearer modification request message.
10. The method of claim 8, wherein the request for processing the
downlink data includes one or more of: a request for maintaining
the buffering of the downlink data; and a request for
retransmitting the downlink data notification after recognizing the
new mobility management server.
11. A user equipment (UE) of performing a tracking area update
(TAU) procedure, the UE comprising: a communication unit configured
to transmit a TAU request message to a target base station as the
UE moves from a source base station to the target base station; and
a controller configured to control the communication unit to
perform a service request procedure or an RRC (Radio Resource
Control) connection procedure immediately after receiving one or
more of information regarding downlink data and information
regarding paging from the target base station through the
communication unit, wherein when the procedure is performed, the
communication unit is configured to receive a paging signal from
the target base station.
12. The UE of claim 11, wherein the information regarding paging
includes one or more of: information indicating that a service
request should be performed in response to the paging; information
regarding which one of a service request message and an extended
service request message should be transmitted in response to the
paging; and information indicating which one of a bearer setup
procedure for a CS (Circuit Switch) call and a bearer setup
procedure for a PS (Packet Switch) call is needed.
13. The UE of claim 11, wherein the one or more information is
received through a TAU accept message or an NAS (Non Access
Stratum)-based message.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a tracking area update
procedure and a paging procedure.
[0003] 2. Related Art
[0004] In 3GPP in which technical standards for mobile
communication systems are established, in order to handle 4th
generation communication and several related forums and new
technologies, research on Long Term Evolution/System Architecture
Evolution (LTE/SAE) technology has started as part of efforts to
optimize and improve the performance of 3GPP technologies from the
end of the year 2004.
[0005] SAE that has been performed based on 3GPP SA WG2 is research
regarding network technology that aims to determine the structure
of a network and to support mobility between heterogeneous networks
in line with an LTE task of a 3GPP TSG RAN and is one of recent
important standardization issues of 3GPP. SAE is a task for
developing a 3GPP system into a system that supports various radio
access technologies based on an IP, and the task has been carried
out for the purpose of an optimized packet-based system which
minimizes transmission delay with a more improved data transmission
capability.
[0006] An Evolved Packet System (EPS) higher level reference model
defined in 3GPP SA WG2 includes a non-roaming case and roaming
cases having various scenarios, and for details therefor, reference
can be made to 3GPP standard documents TS 23.401 and TS 23.402. A
network configuration of FIG. 1 has been briefly reconfigured from
the EPS higher level reference model.
[0007] FIG. 1 shows the configuration of an evolved mobile
communication network.
[0008] An Evolved Packet Core (EPC) may include various elements.
FIG. 1 illustrates a Serving Gateway (S-GW) 52, a Packet Data
Network Gateway (PDN GW) 53, a Mobility Management Entity (MME) 51,
a Serving General Packet Radio Service (GPRS) Supporting Node
(SGSN), and an enhanced Packet Data Gateway (ePDG) that correspond
to some of the various elements.
[0009] The S-GW 52 is an element that operates at a boundary point
between a Radio Access Network (RAN) and a core network and has a
function of maintaining a data path between an eNodeB 22 and the
PDN GW 53. Furthermore, if a terminal (or User Equipment (UE) moves
in a region in which service is provided by the eNodeB 22, the S-GW
52 plays a role of a local mobility anchor point. That is, for
mobility within an E-UTRAN (i.e., a Universal Mobile
Telecommunications System (Evolved-UMTS) Terrestrial Radio Access
Network defined after 3GPP release-8), packets can be routed
through the S-GW 52. Furthermore, the S-GW 52 may play a role of an
anchor point for mobility with another 3GPP network (i.e., a RAN
defined prior to 3GPP release-8, for example, a UTRAN or Global
System for Mobile communication (GSM) (GERAN)/Enhanced Data rates
for Global Evolution (EDGE) Radio Access Network).
[0010] The PDN GW (or P-GW) 53 corresponds to the termination point
of a data interface toward a packet data network. The PDN GW 53 can
support policy enforcement features, packet filtering, charging
support, etc. Furthermore, the PDN GW (or P-GW) 53 can play a role
of 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), a Code Division
Multiple Access (CDMA) network, or a reliable network, such as
WiMax).
[0011] In the network configuration of FIG. 1, the S-GW 52 and the
PDN GW 53 have been illustrated as being separate gateways, but the
two gateways may be implemented in accordance with a single gateway
configuration option.
[0012] The MME 51 is an element for performing the access of a
terminal to a network connection and signaling and control
functions for supporting the allocation, tracking, paging, roaming,
handover, etc. of network resources. The MME 51 controls control
plane functions related to subscribers and session management. The
MME 51 manages numerous eNodeBs 22 and performs conventional
signaling for selecting a gateway for handover to another 2G/3G
networks. Furthermore, the MME 51 performs functions, such as
security procedures, terminal-to-network session handling, and idle
terminal location management.
[0013] The SGSN handles all packet data, such as a user's mobility
management and authentication for different access 3GPP networks
(e.g., a GPRS network and an UTRAN/GERAN).
[0014] The ePDG plays a role of a security node for an unreliable
non-3GPP network (e.g., an I-WLAN and a Wi-Fi hotspot).
[0015] As described with reference to FIG. 1, a terminal (or UE)
having an IP capability can access an IP service network (e.g.,
IMS), provided by a service provider (i.e., an operator), via
various elements within an EPC based on non-3GPP access as well as
based on 3GPP access.
[0016] Furthermore, FIG. 1 shows various reference points (e.g.,
S1-U and S1-MME). In a 3GPP system, a conceptual link that connects
two functions that are present in the different function entities
of an E-UTRAN and an EPC is called a reference point. Table 1 below
defines reference points shown in FIG. 1. In addition to the
reference points shown in the example of Table 1, various reference
points may be present depending on a network configuration.
TABLE-US-00001 TABLE 1 REFERENCE POINT DESCRIPTION S1-MME A
reference point for a control plane protocol between the E-UTRAN
and the MME S1-U A reference point between the E-UTRAN and the S-GW
for path switching between eNodeBs during handover and user plane
tunneling per bearer S3 A reference point between the MME and the
SGSN that provides the exchange of pieces of user and bearer infor-
mation for mobility between 3GPP access networks in idle and/or
activation state. This reference point can be used intra-PLMN or
inter-PLMN (e.g. in the case of Inter-PLMN HO). S4 A reference
point between the SGW and the SGSN that provides related control
and mobility support between the 3GPP anchor functions of a GPRS
core and the S-GW. Furthermore, if a direct tunnel is not
established, the reference point provides user plane tunneling. S5
A reference point that provides user plane tunneling and tunnel
management between the S-GW and the PDN GW. The reference point is
used for S-GW relocation due to UE mobility and if the S-GW needs
to connect to a non-collocated PDN GW for required PDN connec-
tivity S11 A reference point between the MME and the S-GW SGi A
reference point between the PDN GW and the PDN. The PDN may be a
public or private PDN external to an operator or may be an
intra-operator PDN, e.g., for the providing of IMS services. This
reference point corresponds to Gi for 3GPP access.
[0017] Among the reference points shown in FIG. 1, S2a and S2b
correspond to non-3GPP interfaces. S2a is a reference point
providing the user plane with related control and mobility support
between a PDN GW and a reliable non-3GPP access. S2b is a reference
point providing the user plane with mobility support and related
control between a PDN GW and an ePDG.
[0018] FIG. 2 is an exemplary diagram showing the architecture of a
common E-UTRAN and a common EPC.
[0019] As shown in FIG. 2, the eNodeB 20 can perform functions,
such as routing to a gateway while RRC connection is activated, the
scheduling and transmission of a paging message, the scheduling and
transmission of a broadcast channel (BCH), the dynamic allocation
of resources to UE in uplink and downlink, a configuration and
providing for the measurement of the eNodeB 20, control of a radio
bearer, radio admission control, and connection mobility control.
The EPC can perform functions, such as the generation of paging,
the management of an LTE_IDLE state, the ciphering of a user plane,
control of an EPS bearer, the ciphering of NAS signaling, and
integrity protection.
[0020] FIG. 3 is an exemplary diagram showing the structure of a
radio interface protocol in a control plane between UE and an
eNodeB, and FIG. 4 is another exemplary diagram showing the
structure of a radio interface protocol in a control plane between
UE and an eNodeB.
[0021] The radio interface protocol is based on a 3GPP radio access
network standard. The radio interface protocol includes a physical
layer, a data link layer, and a network layer horizontally, and it
is divided into a user plane for the transmission of information
and a control plane for the transfer of a control signal (or
signaling).
[0022] The protocol layers may be classified into a first layer
(L1), a second layer (L2), and a third layer (L3) based on three
lower layers of the Open System Interconnection (OSI) reference
model that is widely known in communication systems.
[0023] The layers of the radio protocol of the control plane shown
in FIG. 3 and the radio protocol in the user plane of FIG. 4 are
described below.
[0024] The physical layer PHY, that is, the first layer, provides
information transfer service using physical channels. The PHY layer
is connected to a Medium Access Control (MAC) layer placed in a
higher layer through a transport channel, and data is transferred
between the MAC layer and the PHY layer through the transport
channel. Furthermore, data is transferred between different PHY
layers, that is, PHY layers on the sender side and the receiver
side, through the PHY layer.
[0025] A physical channel is made up of multiple subframes on a
time axis and multiple subcarriers on a frequency axis. Here, one
subframe is made up of a plurality of symbols and a plurality of
subcarriers on the time axis. One subframe is made up of a
plurality of resource blocks, and one resource block is made up of
a plurality of symbols and a plurality of subcarriers. A
Transmission Time Interval (TTI), that is, a unit time during which
data is transmitted, is 1 ms corresponding to one subframe.
[0026] In accordance with 3GPP LTE, physical channels that are
present in the physical layer of the sender side and the receiver
side can be divided into a Physical Downlink Shared Channel (PDSCH)
and a Physical Uplink Shared Channel (PUSCH), that is, data
channels, and a Physical Downlink Control Channel (PDCCH), a
Physical Control Format Indicator. Channel (PCFICH), a Physical
Hybrid-ARQ Indicator Channel (PHICH), and a Physical Uplink Control
Channel (PUCCH), that is, control channels.
[0027] A PCFICH that is transmitted in the first OFDM symbol of a
subframe carries a Control Format Indicator (CFI) regarding the
number of OFDM symbols (i.e., the size of a control region) used to
send control channels within the subframe. A wireless device first
receives a CFI on a PCFICH and then monitors PDCCHs.
[0028] Unlike a PDCCH, a PCFICH is transmitted through the fixed
PCFICH resources of a subframe without using blind decoding.
[0029] A PHICH carries positive-acknowledgement
(ACK)/negative-acknowledgement (NACK) signals for an uplink (UL)
Hybrid Automatic Repeat reQuest (HARQ). ACK/NACK signals for UL
data on a PUSCH that is transmitted by a wireless device are
transmitted on a PHICH.
[0030] A Physical Broadcast Channel (PBCH) is transmitted in four
former OFDM symbols of the second slot of the first subframe of a
radio frame. The PBCH carries system information that is essential
for a wireless device to communicate with an eNodeB, and system
information transmitted through a PBCH is called a Master
Information Block (MIB). In contrast, system information
transmitted on a PDSCH indicated by a PDCCH is called a System
Information Block (SIB).
[0031] A PDCCH can carry the resource allocation and transport
format of a downlink-shared channel (DL-SCH), information about the
resource allocation of an uplink shared channel (UL-SCH), paging
information for a PCH, system information for a DL-SCH, the
resource allocation of an upper layer control message transmitted
on a PDSCH, such as a random access response, a set of transmit
power control commands for pieces of UE within a specific UE group,
and the activation of a Voice over Internet Protocol (VoIP). A
plurality of PDCCHs can be transmitted within the control region,
and UE can monitor a plurality of PDCCHs. A PDCCH is transmitted on
one Control Channel Element (CCE) or an aggregation of multiple
contiguous CCEs. A CCE is a logical allocation unit used to provide
a PDCCH with a coding rate according to the state of a radio
channel. A CCE corresponds to a plurality of resource element
groups. The format of a PDCCH and the number of bits of a possible
PDCCH are determined by a relationship between the number of CCEs
and a coding rate provided by CCEs.
[0032] Control information transmitted through a PDCCH is called
Downlink Control Information (DCI). DCI can include the resource
allocation of a PDSCH (also called a downlink (DL) grant)), the
resource allocation of a PUSCH (also called an uplink (UL) grant),
a set of transmit power control commands for pieces of UE within a
specific UE group, and/or the activation of a Voice over Internet
Protocol (VoIP).
[0033] Several layers are present in the second layer. First, a
Medium Access Control (MAC) layer functions to map various logical
channels to various transport channels and also plays a role of
logical channel multiplexing for mapping multiple logical channels
to one transport channel. The MAC layer is connected to a Radio
Link Control (RLC) layer, that is, a higher layer, through a
logical channel. The logical channel is basically divided into a
control channel through which information of the control plane is
transmitted and a traffic channel through which information of the
user plane is transmitted depending on the type of transmitted
information.
[0034] The RLC layer of the second layer functions to control a
data size that is suitable for sending, by a lower layer, data
received from a higher layer in a radio section by segmenting and
concatenating the data. Furthermore, in order to guarantee various
types of QoS required by radio bearers, the RLC layer provides
three types of operation modes: a Transparent Mode (TM), an
Un-acknowledged Mode (UM), and an Acknowledged Mode (AM). In
particular, AM RLC performs a retransmission function through an
Automatic Repeat and Request (ARQ) function for reliable data
transmission.
[0035] The Packet Data Convergence Protocol (PDCP) layer of the
second layer performs a header compression function for reducing
the size of an IP packet header containing control information that
is relatively large in size and unnecessary in order to efficiently
send an IP packet, such as IPv4 or IPv6, in a radio section having
a small bandwidth when sending the IP packet. Accordingly,
transmission efficiency of the radio section can be increased
because only essential information is transmitted in the header
part of data. Furthermore, in an LTE system, the PDCP layer also
performs a security function. The security function includes
ciphering for preventing the interception of data by a third party
and integrity protection for preventing the manipulation of data by
a third party.
[0036] A Radio Resource Control (RRC) layer at the highest place of
the third layer is defined only in the control plane and is
responsible for control of logical channels, transport channels,
and physical channels in relation to the configuration,
re-configuration, and release of Radio Bearers (RBs). Here, the RB
means service provided by the second layer in order to transfer
data between UE and an E-UTRAN.
[0037] If an RRC connection is present between the RRC layer of UE
and the RRC layer of a wireless network, the UE is in an
RRC_CONNECTED state. If not, the UE is in an RRC_IDLE state.
[0038] An RRC state and an RRC connection method of UE are
described below. The RRC state means whether or not the RRC layer
of UE has been logically connected to the RRC layer of an E-UTRAN.
If the RRC layer of UE is logically connected to the RRC layer of
an E-UTRAN, it is called the RRC_CONNECTED state. If the RRC layer
of UE is not logically connected to the RRC layer of an E-UTRAN, it
is called the RRC_IDLE state. Since UE in the RRC_CONNECTED state
has an RRC connection, an E-UTRAN can check the existence of the UE
in a cell unit, and thus control the UE effectively. In contrast,
if UE is in the RRC_IDLE state, an E-UTRAN cannot check the
existence of the UE, and a core network is managed in a Tracking
Area (TA) unit, that is, an area unit greater than a cell. That is,
only the existence of UE in the RRC_IDLE state is checked in an
area unit greater than a cell. In such a case, the UE needs to
shift to the RRC_CONNECTED state in order to be provided with
common mobile communication service, such as voice or data. Each TA
is classified through Tracking Area Identity (TAI). UE can
configure TAI through Tracking Area Code (TAC), that is,
information broadcasted by a cell.
[0039] When a user first turns on the power of UE, the UE first
searches for a proper cell, establishes an RRC connection in the
corresponding cell, and registers information about the UE with a
core network. Thereafter, the UE stays in the RRC_IDLE state. The
UE in the RRC_IDLE state (re)selects a cell if necessary and checks
system information or paging information. This process is called
camp on. When the UE in the RRC_IDLE state needs to establish an
RRC connection, the UE establishes an RRC connection with the RRC
layer of an E-UTRAN through an RRC connection procedure and shifts
to the RRC_CONNECTED state. A case where the UE in the RRC_IDLE
state needs to establish with an RRC connection includes multiple
cases. The multiple cases may include, for example, a case where UL
data needs to be transmitted for a reason, such as a call attempt
made by a user and a case where a response message needs to be
transmitted in response to a paging message received from an
E-UTRAN.
[0040] A Non-Access Stratum (NAS) layer placed over the RRC layer
performs functions, such as session management and mobility
management.
[0041] The NAS layer shown in FIG. 3 is described in detail
below.
[0042] Evolved Session Management (ESM) belonging to the NAS layer
performs functions, such as the management of default bearers and
the management of dedicated bearers, and ESM is responsible for
control that is necessary for UE to use PS service from a network.
Default bearer resources are characterized in that they are
allocated by a network when UE first accesses a specific Packet
Data Network (PDN) or accesses a network. Here, the network
allocates an IP address available for UE so that the UE can use
data service and the QoS of a default bearer. LTE supports two
types of bearers: a bearer having Guaranteed Bit Rate (GBR) QoS
characteristic that guarantees a specific bandwidth for the
transmission and reception of data and a non-GBR bearer having the
best effort QoS characteristic without guaranteeing a bandwidth. A
default bearer is assigned a non-GBR bearer, and a dedicated bearer
may be assigned a bearer having a GBR or non-GBR QoS
characteristic.
[0043] In a network, a bearer assigned to UE is called an Evolved
Packet Service (EPS) bearer. When assigning an EPS bearer, a
network assigns one ID. This is called an EPS bearer ID. One EPS
bearer has QoS characteristics of a Maximum Bit Rate (MBR) and a
Guaranteed Bit Rate (GBR) or an Aggregated Maximum Bit Rate
(AMBR).
[0044] FIG. 5 is a flowchart illustrating a random access process
in 3GPP LTE.
[0045] The random access process is used for UE 10 to obtain UL
synchronization with a base station, that is, an eNodeB 20, or to
be assigned UL radio resources.
[0046] The UE 10 receives a root index and a physical random access
channel (PRACH) configuration index from the eNodeB 20. 64
candidate random access preambles defined by a Zadoff-Chu (ZC)
sequence are present in each cell. The root index is a logical
index that is used for the UE to generate the 64 candidate random
access preambles.
[0047] The transmission of a random access preamble is limited to
specific time and frequency resources in each cell. The PRACH
configuration index indicates a specific subframe on which a random
access preamble can be transmitted and a preamble format.
[0048] The UE 10 sends a randomly selected random access preamble
to the eNodeB 20. Here, the UE 10 selects one of the 64 candidate
random access preambles. Furthermore, the UE selects a subframe
corresponding to the PRACH configuration index. The UE 10 sends the
selected random access preamble in the selected subframe.
[0049] The eNodeB 20 that has received the random access preamble
sends a Random Access Response (RAR) to the UE 10. The random
access response is detected in two steps. First, the UE 10 detects
a PDCCH masked with a random access-RNTI (RA-RNTI). The UE 10
receives a random access response within a Medium Access Control
(MAC) Protocol Data Unit (PDU) on a PDSCH that is indicated by the
detected PDCCH.
[0050] FIG. 6 illustrates a connection process in a radio resource
control (RRC) layer.
[0051] FIG. 6 shows an RRC state depending on whether there is an
RRC connection. The RRC state denotes whether the entity of the RRC
layer of UE 10 is in logical connection with the entity of the RRC
layer of eNodeB 20, and if yes, it is referred to as RRC connected
state, and if no as RRC idle state.
[0052] In the connected state, UE 10 has an RRC connection, and
thus, the E-UTRAN may grasp the presence of the UE on a cell basis
and may thus effectively control UE 10. In contrast, UE 10 in the
idle state cannot grasp eNodeB 20 and is managed by a core network
on the basis of a tracking area that is larger than a cell. The
tracking area is a set of cells. That is, UE 10 in the idle state
is grasped for its presence only on a larger area basis, and the UE
should switch to the connected state to receive a typical mobile
communication service such as voice or data service.
[0053] When the user turns on UE 10, UE 10 searches for a proper
cell and stays in idle state in the cell. UE 10, when required,
establishes an RRC connection with the RRC layer of eNodeB 20
through an RRC connection procedure and transits to the RRC
connected state.
[0054] There are a number of situations where the UE staying in the
idle state needs to establish an RRC connection, for example, when
the user attempts to call or when uplink data transmission is
needed, or when transmitting a message responsive to reception of a
paging message from the EUTRAN.
[0055] In order for the idle UE 10 to be RRC connected with eNodeB
20, UE 10 needs to perform the RRC connection procedure as
described above. The RRC connection procedure generally comes with
the process in which UE 10 transmits an RRC connection request
message to eNodeB 20, the process in which eNodeB 20 transmits an
RRC connection setup message to UE 10, and the process in which UE
10 transmits an RRC connection setup complete message to eNodeB 20.
The processes are described in further detail with reference to
FIG. 6.
[0056] 1) The idle UE 10, when attempting to establish an RRC
connection, e.g., for attempting to call or transmit data or
responding to paging from eNodeB 20, sends an RRC connection
request message to eNodeB 20.
[0057] 2) When receiving the RRC connection message from UE 10,
eNodeB 20 accepts the RRC connection request from UE 10 if there
are enough radio resources, and eNodeB 20 sends a response message,
RRC connection setup message, to UE 10.
[0058] 3) When receiving the RRC connection setup message, UE 10
transmits an RRC connection setup complete message to eNodeB 20. If
UE 10 successfully transmits the RRC connection setup message, UE
10 happens to establish an RRC connection with eNodeB 20 and
switches to the RRC connected state.
[0059] FIG. 7 shows an example in which a UE geographically moves,
and FIG. 8 shows a problem that may arise in the example shown in
FIG. 7.
[0060] As can be seen from FIG. 7, a first eNodeB 20a is connected
with a first MME 51a, and a second eNodeB 20b with a second MME
51b.
[0061] UE 10 remains in RRC idle state in the coverage of the first
eNodeB 20a. While UE 10 shifts from the coverage of the first
eNodeB 20a to the coverage of the second eNodeB 20b, first MME 51a
which has data to transmit to the UE sends a paging signal to the
first eNodeB 20a as shown in FIG. 8.
[0062] Since the UE 10 which has been in RRC idle state in the
coverage of the first eNodeB 20a moves into the coverage of the
second eNodeB 20b, the UE 10 transmits a tracking area update (TAU)
request to the second MME 52b through the second eNodeB 20b.
[0063] Meanwhile, the first eNodeB 20a fails to receive a response
to the paging signal from the UE 10. Assume that the paging signal
is a call. In this case, the UE 10 fails to receive a paging signal
responsive to call reception, the UE 10 does not produce a bell
sound or vibration, so that the user is not alerted. Further, the
calling side suffers from call failure without any special
reason.
SUMMARY OF THE INVENTION
[0064] The present disclosure aims to propose a method for
addressing the above issues.
[0065] To achieve the above objects, the present disclosure
provides a method of performing tracking area update (TAU). The
method may be performed by a user equipment (UE) and comprise:
transmitting a TAU request message to a target base station as the
UE moves from a source base station to the target base station;
performing a service request procedure or an RRC (Radio Resource
Control) connection procedure immediately after receiving one or
more of information regarding downlink data and information
regarding paging from the target base station; and receiving a
paging signal from the target base station after the procedure.
[0066] The information regarding paging may include one or more of:
information indicating that a service request should be performed
in response to the paging; information regarding which one of a
service request message and an extended service request message
should be transmitted in response to the paging; and information
indicating which one of a bearer setup procedure for a CS (Circuit
Switch) call and a bearer setup procedure for a PS (Packet Switch)
call is needed.
[0067] The one or more information may be received through a TAU
accept message or an NAS (Non Access Stratum)-based message.
[0068] The service request procedure may include transmitting an
NAS-based service request message.
[0069] The RRC connection procedure may include: receiving an RRC
connection reconfiguration message from the target base station;
and transmitting an RRC connection reconfiguration complete message
to the target base station in response to the reception of the RRC
connection reconfiguration message.
[0070] The RRC connection procedure may include: receiving an
RRC-based radio bearer setup message from the target base station;
and transmitting an RRC-based radio bearer setup complete message
to the target base station in response to the reception of the
RRC-based radio bearer setup message.
[0071] The RRC connection procedure may include: transmitting an
RRC connection request message to the target base station;
receiving an RRC connection setup message from the target base
station; and transmitting an RRC connection setup complete message
in response to the reception of the RRC connection setup
message.
[0072] Meanwhile, to achieve the above objects, the present
disclosure provides a method of transferring downlink data for a
user equipment from a network node. The method may comprise:
transmitting a downlink data notification to a mobility management
server for the UE when receiving downlink supposed to be
transferred to the UE; receiving a request for processing the
downlink data from the mobility management server; maintaining
buffering without deleting the downlink data in response to the
request; and retransmitting the downlink data notification to a new
mobility management server for the UE.
[0073] The method may further comprise: receiving a bearer
modification request message from the new mobility management
server, wherein retransmitting the notification is performed after
receiving the bearer modification request message.
[0074] The request for processing the downlink data may include one
or more of: a request for maintaining the buffering of the downlink
data; and a request for retransmitting the downlink data
notification after recognizing the new mobility management
server.
[0075] Meanwhile, to achieve the above objects, the present
disclosure provides a user equipment (UE) of performing a tracking
area update (TAU) procedure. The UE may comprise: a communication
unit configured to transmit a TAU request message to a target base
station as the UE moves from a source base station to the target
base station; and a controller configured to control the
communication unit to perform a service request procedure or an RRC
(Radio Resource Control) connection procedure immediately after
receiving one or more of information regarding downlink data and
information regarding paging from the target base station through
the communication unit, wherein when the procedure is performed,
the communication unit is configured to receive a paging signal
from the target base station.
[0076] The present disclosure may enhance service quality while
preventing waste of paging cancellation network resources with a
reduced call reception delay and an increased call reception
success rate.
[0077] In particular, as set forth herein, the source MME 510a may
be aware, by the TAU procedure, that the UE has been relocated
earlier than the S-GW, and thus, the source MME 510a may recognize
that paging will fail earlier than anything else. More
specifically, the source MME may be aware through context exchange
of the TAU procedure that the UE has moved his position, and the
S-GW may happen to know that through a subsequent procedure, bearer
modification process. As a result, the source MME 510a may be aware
that paging will fail earlier than anything else. Accordingly,
according to an embodiment of the present invention, the procedure
performed by the source MME 510a may come effective.
[0078] Meanwhile, according to an embodiment of the present
invention, the target MME may choose the optimal one among several
schemes. For example, although transmitting a downlink notification
is best for the S-GW, the target MME may select the most
appropriate scheme among directly triggering/performing triggering,
re-requesting the S-GW, and directly requesting the UE or eNB to
set up a user plane bearer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0079] FIG. 1 is a view illustrating the structure of an evolved
mobile communication network.
[0080] FIG. 2 is an exemplary view illustrating functions of main
nodes of a common E-UTRAN and a common EPC.
[0081] FIG. 3 is an exemplary view illustrating the structure of a
radio interface protocol in a control plane between a UE and an
eNodeB.
[0082] FIG. 4 is another exemplary view illustrating the structure
of a radio interface protocol in a user plane between a UE and a
base station.
[0083] FIG. 5 is a flowchart illustrating a random access procedure
in 3GPP LTE.
[0084] FIG. 6 illustrates a connection process in a radio resource
control (RRC) layer.
[0085] FIG. 7 illustrates an example in which a UE geographically
relocates.
[0086] FIG. 8 illustrates a problem that may arise in the example
shown in FIG. 7.
[0087] FIG. 9 is an exemplary view illustrating a TAU (Tracking
Area Update) procedure.
[0088] FIG. 10 is an exemplary view illustrating a TAU (Tracking
Area Update) procedure as proposed herein.
[0089] FIG. 11 is an exemplary view illustrating a TAU (Tracking
Area Update) according to a first embodiment of the present
invention.
[0090] FIG. 12 is an exemplary view illustrating a TAU (Tracking
Area Update) according to a second embodiment of the present
invention.
[0091] FIG. 13 is an exemplary view illustrating a TAU (Tracking
Area Update) according to a third embodiment of the present
invention.
[0092] FIG. 14 is an exemplary view illustrating a TAU (Tracking
Area Update) according to a fourth embodiment of the present
invention.
[0093] FIG. 15 is an exemplary view illustrating a TAU (Tracking
Area Update) according to a fifth embodiment of the present
invention.
[0094] FIG. 16 is an exemplary view illustrating a TAU (Tracking
Area Update) according to a sixth embodiment of the present
invention.
[0095] FIG. 17 is an exemplary view illustrating a TAU (Tracking
Area Update) according to a seventh embodiment of the present
invention.
[0096] FIG. 18 is a view illustrating an exemplary protocol and
interfaces between a UE, an eNodeB, and an MME.
[0097] FIG. 19 is a block diagram illustrating the configuration of
an MTC device 100, an MME 510, and an SGSN 520 according to an
embodiment of the present invention.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0098] The present invention is described in light of UMTS
(Universal Mobile Telecommunication System) and EPC (Evolved Packet
Core), but not limited to such communication systems, and may be
rather applicable to all communication systems and methods to which
the technical spirit of the present invention may apply.
[0099] The technical terms used herein are used to merely describe
specific embodiments and should not be construed as limiting the
present invention. Further, the technical terms used herein should
be, unless defined otherwise, interpreted as having meanings
generally understood by those skilled in the art but not too
broadly or too narrowly. Further, the technical terms used herein,
which are determined not to exactly represent the spirit of the
invention, should be replaced by or understood by such technical
terms as being able to be exactly understood by those skilled in
the art. Further, the general terms used herein should be
interpreted in the context as defined in the dictionary, but not in
an excessively narrowed manner.
[0100] The expression of the singular number in the specification
includes the meaning of the plural number unless the meaning of the
singular number is definitely different from that of the plural
number in the context. In the following description, the term
`include` or `have` may represent the existence of a feature, a
number, a step, an operation, a component, a part or the
combination thereof described in the specification, and may not
exclude the existence or addition of another feature, another
number, another step, another operation, another component, another
part or the combination thereof.
[0101] The terms `first` and `second` are used for the purpose of
explanation about various components, and the components are not
limited to the terms `first` and `second`. The terms `first` and
`second` are only used to distinguish one component from another
component. For example, a first component may be named as a second
component without deviating from the scope of the present
invention.
[0102] It will be understood that when an element or layer is
referred to as being "connected to" or "coupled to" another element
or layer, it can be directly connected or coupled to the other
element or layer or intervening elements or layers may be present.
In contrast, when an element is referred to as being "directly
connected to" or "directly coupled to" another element or layer,
there are no intervening elements or layers present.
[0103] Hereinafter, exemplary embodiments of the present invention
will be described in greater detail with reference to the
accompanying drawings. In describing the present invention, for
ease of understanding, the same reference numerals are used to
denote the same components throughout the drawings, and repetitive
description on the same components will be omitted. Detailed
description on well-known arts which are determined to make the
gist of the invention unclear will be omitted. The accompanying
drawings are provided to merely make the spirit of the invention
readily understood, but not should be intended to be limiting of
the invention. It should be understood that the spirit of the
invention may be expanded to its modifications, replacements or
equivalents in addition to what is shown in the drawings.
[0104] In the drawings, user equipments (UEs) are shown for
example. The UE may also be denoted a terminal or mobile equipment
(ME). The UE may be a laptop computer, a mobile phone, a PDA, a
smartphone, a multimedia device, or other portable device, or may
be a stationary device such as a PC or a car mounted device.
DEFINITION OF TERMS
[0105] For a better understanding, the terms used herein are
briefly defined before going to the detailed description of the
invention with reference to the accompanying drawings.
[0106] UMTS: stands for Universal Mobile Telecommunication System
and means a 3rd generation mobile communication network.
[0107] UE/MS: User Equipment/Mobile Station. Means a terminal
device.
[0108] EPC: stands for Evolved Packet Core and means a core network
supportive of a long term evolution (LTE) network. An evolved
version of UMTS
[0109] EPS: stands for Evolved Packet System and means a mobile
communication system including a UE, an access network including
LTE, and an EPC
[0110] PDN (Public Data Network): an independent network in which a
service providing server is located
[0111] PDN connection: connection from UE to PDN, i.e., association
(connection) between a UE represented with an IP address and a PDN
represented with an APN (access point name)
[0112] PDN-GW (Packet Data Network Gateway): a network node of an
EPS network performing functions such as UE IP address allocation,
packet screening & filtering, and charging data collection
[0113] Serving GW (Serving Gateway): a network node of an EPS
network performing functions such as mobility anchor, packet
routing, idle mode packet buffering, and triggering MME to page
UE
[0114] PCRF (Policy and Charging Rule Function): an EPS network
node performing policy decision for dynamically applying QoSs and
billing policies differentiated per service flow
[0115] APN (Access Point Name): name of an access point managed by
a network, provided from a UE, i.e., a character string for
denoting a PDN or distinguishing a PDN from another. Accessing a
requested service or network (PDN) gets through a corresponding
P-GW, and an APN is a name (e.g., internet.mnc012.mcc345.gprs)
pre-defined in the network to be able to discover the P-GW.
[0116] TEID (Tunnel Endpoint Identifier): End point ID of a tunnel
configured between nodes in a network. A TEID is configured per
section by the bearer of each UE.
[0117] NodeB: a UMTS network base station. A NodeB is installed
outdoors and corresponds in cell coverage size to a macro cell.
[0118] eNodeB: an EPS (Evolved Packet System) base station and is
installed outdoors. An eNodeB corresponds in cell coverage size to
a macro cell.
[0119] (e)NodeB: collectively denotes NodeB and eNodeB
[0120] MME: stands for Mobility Management Entity and plays a role
to control each entity in an EPS to provide mobility and session
for a UE.
[0121] Session: a pathway for data transmission. The unit of
session may include PDN, bearer, and IP flow which respectively
correspond the unit of the overall target network (unit of APN or
PDN), the unit distinguished by QoS therein (unit of bearer), and
unit of destination IP address.
[0122] PDN connection: a connection from a UE to a PDN, i.e., an
association (connection) between a UE represented with an IP
address and a PDN represented with an APN. This means a connection
(UE-PDN GW) between entities in a core network to form a
session.
[0123] UE Context: information on UE's context used to manage UE in
network, i.e., context information consisting of UE id, mobility
(e.g., current location), and session attribute (QoS, or
priority)
[0124] OMA DM (Open Mobile Alliance Device Management): a protocol
designed for managing mobile devices such as mobile phones, PDAs,
or portable computers and performs functions such as device
configuration, firmware upgrade, and error reporting.
[0125] OAM (Operation Administration and Maintenance): denotes a
group of network management functions displaying network faults and
providing capability information, diagnosis and data.
[0126] NAS configuration MO (Management Object): MO (Management
Object) used to configure in UE parameters associated with NAS
functionality
[0127] Hereinafter, the present disclosure is described with
reference to the accompanying drawings.
[0128] FIG. 9 shows an exemplary TAU (Tracking Area Update)
procedure.
[0129] 1) In idle mode, the UE 100 moves into the coverage of the
target eNodeB 200b. Accordingly, a TAU (Tracking Area Update)
procedure is determined to start.
[0130] 2) Then, the UE 100 sends a TAU request message to the
target eNodeB 200b.
[0131] 3) Then, the target eNodeB 200b determines a responsible
MME. In this case, assume, for example, that the target MME 510b is
determined as a proper responsible MME. The target eNodeB 200b
transfers the TAU request message to the target MME 510b. In this
case, assume that the S-GW 520 is not changed.
[0132] 4-5) Then, the target MME 510b sends the UE's context
request (e.g., Context Request) to the source MME 510a, and in
response, receives a context response (e.g., Context Response).
This is a process to obtain PDN connection-related information and
EPS bearer-related information from the source MME 510a.
[0133] 6) The UE 100 conducts an authentication/security procedure
with the target MME 510b, and the target MME 510b conducts a
security procedure with the HSS 590.
[0134] 7) Meanwhile, the target MME 510b transmits to the source
MME 510a a context acknowledge (e.g., Context Acknowledge) message
in response to obtaining the context.
[0135] 8) Subsequently, the target MME 510b, since the S-GW 520 is
not changed by the TAU, transmits to the S-GW 520 a bearer
modification request message (e.g., Modify Bearer Request), not a
session creation request message (e.g., Create Session
Request).
[0136] 9-11) Then, the S-GW 520 transmits a bearer modification
request message to the PDN-GW 530 as necessary. The PDN-GW 530
performs an IP-CAN session modification procedure as necessary. The
PDN-GW 530 transmits a bearer modification response message (e.g.,
Modify Bearer Response) to the S-GW 520.
[0137] 12) Then, the S-GW 520 transmits a bearer modification
response message to the target MME 510b.
[0138] 13) Then, the target MME 510b transmits to the HSS 590 a
location update request message (e.g., Update Location
Request).
[0139] 14-15) Then, the HSS 590 transmits a location cancel message
(e.g., Cancel Location) to the source MME 510a, and the source MME
510a transmits a location cancel acknowledgement message (e.g.,
Cancel Location Ack) to the HSS 590.
[0140] 16) Then, the HSS 590 transmits a location update
acknowledgement message (e.g., Update Location Ack) to the target
MME 510b.
[0141] 17-18) Then, the target MME 510b transmits a TAU accept
message (e.g., TAU accept) to the UE 100 through the target eNodeB
200b, and the UE 100 transmits a TAU complete message (e.g., TAU
Complete) to the target MME 510b as necessary.
[0142] Hereinafter, the following Table 2 to Table 9 show the
messages used in each process.
[0143] First, the TAU request message may contain one or more
pieces of information as shown in Table 2.
TABLE-US-00002 TABLE 2 Protocol discriminator Security header type
Tracking area update request message identity EPS update type NAS
key set identifier Old GUTI Non-current native NAS key set
identifier GPRS ciphering key sequence number Old P-TMSI signature
Additional GUTI NonceUE UE network capability Last visited
registered TAI DRX parameter UE radio capability information update
needed EPS bearer context status MS network capability Old location
area identification TMSI status Mobile station classmark 2 Mobile
station classmark 3 Supported Codecs Additional update type Voice
domain preference and UE's usage setting Old GUTI type Device
properties MS network feature support TMSI based NRI container
[0144] The EPC Update type information element shown in Table 2
above may contain the following bits.
TABLE-US-00003 TABLE 3 EPC Update Type Value 000: indicates TAU
001: indicates joint update of TAU/LA(Location Area) 010: indicates
joint update of TAU/LA (Location Area) together with IMSI attach
011: indicates periodic update 100: unused (if used, interpreted as
TAU) 101: unused (if used, interpreted as TAU) "Active" flag (octet
1, bit 4) 0: bearer creation not requested 1: bearer creation
requested
[0145] Meanwhile, the above-described context request message may
contain the information elements shown in the following Table
4.
TABLE-US-00004 TABLE 4 Information elements Conditions/descriptions
IMSI should be included in case UE successfully authen- ticated
GUTI A new target MME should include over S10 interface may be
included if SRVCC procedure from UTRAN/ GERN to E-UTRAN is
available Complete TAU a new target MME may include if previous
source request message MME needs it for acknowledgement of no
decision RAT Type indicates what radio access technology is in use
Target PLMN if available, may be included for previous MME to ID
determine whether unused authentication vector is to be distributed
MME node is transferred by a new target MME if the new name target
MME and associated S-GW both support SR
[0146] Meanwhile, the context response message may contain the
information elements shown in the following Table 5.
TABLE-US-00005 TABLE 5 Information element Conditions/descriptions
IMSI IMSI necessarily included except emergency even when UE does
not have UICC MME/SGSN UE Included in case at least one PDN
connection is EPS PDN present for UE. Connections SGW node
Indicates the identifier that has been used to identify name S-GW
by previous source MME Trace may be included in case session
tracking is activated Information Subscribed RFSP May be included
during mobility procedure between Index MMEs UE Time Zone Included
by source MME MME node name Transmitted by previous source MME in
case previous MME and associated S-GW both support ISR
[0147] The information on the PDN connection in the context
response message may contain the information elements shown in the
following Table 6.
TABLE-US-00006 TABLE 6 APN Indicates limitations on combinations of
APN types Restriction for APNs related to bearer context. Target
MME or SGSN may determine the largest APN limitation using the APN
limitations. Linked EPS Indicates basic bearer of PDN connection
Bearer ID PGW node name may be included in case source MME has the
overall name (e.g., FQDN) of PDN GW Bearer Contexts a number of
pieces of information of such type may be included Charging May be
included in case billing information is characteristics offered by
HSS to MME Change Reporting May be included whenever available by
source MME Action
[0148] The bearer context information included in the PDN
connection information in the context response may contain the
information shown in the following Table 7.
TABLE-US-00007 TABLE 7 Information elements Conditions/descriptions
PGW S5/S8 IP May be included for GTP-based S5/S8 Address and TEID
for user plane Bearer Level QoS BSS Container MME may include
packet flow ID, radio priority, SAPI, PS handover XID parameter in
TAU/RAU/ handover procedure-related message Transaction may be
transmitted over S3/S10/S16 in case UE Identifier supports A/Gb
and/or Iu mode
[0149] The TAU accept message may contain the information shown in
the following Table 8.
TABLE-US-00008 TABLE 8 Information Description TAU accept message
message identifier identifier TAU result indicate result of update,
e.g. success or fail T3412 value timer value for periodic TAU T3402
value timer starting upon TAU failure T3412 extended value extended
value of T3412 for further lengthening periodic TAU
[0150] In Table 8 above, the T3412 value is a value for allowing
the UE 100 to conduct periodic TAU. In order to reduce network load
by such periodic TAU, the T3412 extended value is present which
allows TAU to be conducted at a longer period. The T3412 extended
value may be set up in the MME or may be retained as subscriber
information in the HSS 540.
[0151] 19) Meanwhile, while the UE 100 performs a TAU procedure as
above, as described in the Background section, the source MME 510a
has data to transmit to the UE 10, it may transmit a paging signal
to the source eNodeB 200a. The UE 100 has moved to the inside of
the coverage of the target eNodeB 200b, and thus, it cannot receive
a paging signal from the source eNodeB 200a.
[0152] The source MME 510a, unless receiving from the source eNodeB
200a a response to the paging signal until before a paging-related
time value, e.g., the T3413 timer expires, the source MME 510a
re-transmits the paging signal. The paging-related time value,
e.g., the T3413 timer, may be a timer for re-transmission of the
paging signal.
[0153] Resultantly, the paging signal is re-transmitted a
predetermined number of times, and the caller is encountered with
the situation where it keeps receiving the ring back tone.
[0154] Thereafter, if reaching the predetermined number of times,
the source MME 510a reports paging failure to the S-GW. As a
result, the calling side has inconvenience of call failure without
any special reason, and the user of the UE 100 does not produce a
bell sound or vibration because he has not received the paging for
call reception, and thus, the user cannot receive any
notification.
[0155] Schemes to address such inconvenience are now described. A
brief description, prior to advancing to the details, is given
below with the following two schemes.
[0156] (1) A scheme for enhancing quality of user service by
reducing call reception delay
[0157] The target MME 510b, after receiving a context response from
the source MME 510a during a TAU procedure, i) identifies whether
there is a specific indication as suggested herein. The specific
indication indicates that the source MME 510a has done an activity
for conducting paging on the UE or that the target MME 510b has
received a downlink data notification on the UE from the S-GW.
Subsequently, the target MME 510b ii) includes the specific
indication in a TAU accept message and transmits the same to the UE
100. The specific indication may be contained in the TAU accept
message to indicate that there is an operation that should be
conducted when receiving a paging message or to inform the UE of
presence of downlink data. The target MME 510b iii) conducts an
operation for separately configuring a user plane bearer. For
example, the target MME 510b transmits an initial context setup
message to the target eNodeB 200b or may conduct a process for
activating the user plane bearer of radio section for downlink data
transmission.
[0158] (2) A scheme for avoiding waste of network resources due to
repetitive paging
[0159] The target MME 510b, when receiving a context response from
the source MME 510a during a TAU procedure, i) identifies whether
there is a specific indication as suggested herein. The specific
indication indicates that the source MME 510a has done an activity
for conducting paging on the UE or that the target MME 510b has
received a downlink data notification on the UE from the S-GW. ii)
Subsequently, the target MME 510b may transmit to the source MME
510a a message for stopping paging. iii) Further, the target MME
510b may inform the S-GW that the previous downlink data
notification should be canceled by separately sending to the S-GW
information indicating that the UE has moved. The information
allows the S-GW to stop waiting for a response to the paging
transmitted previously. More actively, the target MME 510b may send
to the source MME 510a a message for requesting to stop paging.
[0160] The above described two schemes may be summarized as follows
in light of activity.
[0161] 1) The target MME 510b determines whether the UE to which a
paging signal is to be sent has moved, and if so, whether a TAU
procedure proceeds. For example, the target MME 510b determines
whether the UE to which a paging signal is to be transmitted has
moved during the context exchange process between the target MME
510b and the source MME 510a and whether the TAU procedure is
underway, and accordingly, the target MME 510b may request the
source MME 510a to stop paging.
[0162] 2) The target MME 510b may inform the S-GW 520 of what it
has recognized in process 1) above during the message exchange for
modifying bearer between the target MME 510b and the S-GW 520. In
this process, the target MME 510b may send a request for stopping
paging to the S-GW 520. Or, when receiving what has been
recognized, the S-GW 520 may recognize that the paging procedure is
not further required and conduct a subsequent procedure for
canceling/stopping the paging procedure.
[0163] 3) When transmitting a TAU accept message to the UE, the
target MME 510b may add to the message information for enabling the
UE 100 to start a task that the UE 100 should do when receiving a
paging signal in the future. This allows the UE to get ready before
receiving a paging signal to reduce a delay before receiving the
paging signal, thus immediately enabling a user plane bearer to be
set up.
[0164] 4) When receiving the TAU accept message, the UE 100
immediately performs setup of a user plane bearer. Or, setup of a
user plane bearer which is initiated by a network is immediately
done by the network.
[0165] A more detailed description is given below in connection
with the drawings.
[0166] FIG. 10 is a view illustrating an exemplary TAU (Tracking
Area Update) procedure as proposed herein.
[0167] The overall process is similar to that described above in
connection with FIG. 9. Hereinafter, differences between the two
processes are primarily described, with no repetitive description
made.
[0168] As per the procedure illustrated in FIG. 10, a condition is
added to trigger the setup of a user plane bearer to put the setup
of the user plane bearer in an earlier time.
[0169] 1) The S-GW 520, upon reception of downlink data to be
transmitted to the UE 100, stores the downlink data in a buffer and
identifies which MME is in charge of the UE 100.
[0170] 2) The S-GW 520 transmits a downlink data notification to
the source MME 510a. The downlink data notification may include an
ARP, an EPS, a bearer ID, etc.
[0171] 3) The source MME 510a transmits a downlink data
notification acknowledgement message to the S-GW 520.
[0172] 4) Subsequently, the source MME 510a transmits paging
signals to all the eNodeBs (including the source eNodeB 200a)
belonging to the tracking area where the UE 100 is in registration
in order to convey the paging signal to the UE 100. In this case,
the source MME 510a may use the EPS bearer ID included in the
downlink data notification message received from the S-GW 520 in
order to apply and control a paging-related policy. That is, the
source MME 510a may identify the EPS bearer context information
stored in the MME by the EPS bearer ID.
[0173] However, the idle UE 100 departs from the coverage of the
source eNodeB 200a to the coverage of the target eNodeB 200b.
Accordingly, the UE 100 cannot receive the paging signal.
[0174] 5-6) Accordingly, the UE 100 transmits a TAU request message
to the target MME 510b through the target eNodeB 200b, and the
target MME 510b transmits a context request message to the source
MME 510a.
[0175] 7) The source MME 510a transmits a context response message
to the target MME 510b. In this process, the source MME 510a may
inform the target MME 510b that the paging signal has been
transmitted to the UE 100. This information may be direct
information or may be transferred in various forms of implicit
information so that the target MME 510b may recognize the same. Or,
the target MME 510b may realize any problematic situation based on
additional information collected from the eNodeB or other network
node.
[0176] 8) An authentication/security procedure is performed as
described above.
[0177] 9) The target MME 510b transmits a context acknowledgement
message to the source MME 510a. In this process, the target MME
510b may include in the message information for canceling or
stopping the existing paging.
[0178] 10) The target MME 510b transmits a bearer modification
request message to the S-GW 520. In this process, the target MME
510b may inform the S-GW 520 of what it has recognized.
Additionally, in this process, the target MME 510b may include in
the message information for canceling or stopping paging. That is,
when obtaining the recognized information, the S-GW 520 realizes no
further paging process is required, conducting a subsequent
procedure for canceling or stopping the previous paging.
[0179] 11) The S-GW 520 transmits a bearer modification response
message to the target MME 510b. In this process, the S-GW 520 may
include in the message information indicating advancing the time of
setup of a user plane bearer. This information may contain
information that may have an effect on when the target MME 510b
creates a message to be transmitted to the UE 100, and additional
information to be used for setup of a user plane bearer, if needed,
may be transmitted together. Or, the information included in the
downlink data notification may be additionally included.
[0180] 12) As described above, the target MME 510b transmits a
location update request message to the HSS 590.
[0181] 13-14) As described above, the HSS 590 transmits a location
cancel message to the source MME 510a and receives a location
cancel acknowledgement message. In this case, some of the above
mentioned pieces of information may be stored in the HSS 590.
[0182] 15) The target MME 510b transmits a TAU accept message to
the UE 100. In this process, the TAU accept message may include an
indication for indicating that setup of a user plane bearer be
immediately performed like the UE 100 is the UE targeted for the
previous paging and a service request procedure should be performed
in response to the paging. For example, the indication may be of a
form similar to the "active flag." The "active flag" is included in
the TAU request message as shown in Table 2, and this may be
included in the TAU accept message according to an embodiment of
the present invention.
[0183] Meanwhile, the target MME 510b may first initiate an
operation for user plane bearer setup. For example, in case the
active flag is conventionally included in the TAU request message,
the user plane bearer setup may be performed immediately when the
TAU accept message is transmitted. As an application thereto, the
target MME 510b may include the active flag in the TAU accept
message and transmit the same, so that the user plane bearer setup
procedure may be immediately conducted.
[0184] 16) The UE may transmit a TAU complete message to the source
MME 510a as necessary.
[0185] 17) Meanwhile, the UE 100 may perform a service request
procedure when receiving the TAU accept message like it receives a
paging signal. For example, in case the TAU accept message includes
the active flag, it may perform a service request procedure like it
received a paging signal. Or, other processes necessary for user
plane bearer setup (procedure for setup of a radio bearer between
the UE and the eNodeB) may come along.
[0186] FIG. 11 is a view illustrating an exemplary TAU (Tracking
Area Update) procedure according to a first embodiment of the
present invention.
[0187] FIG. 11 illustrates a scheme that may be conducted by the
source MME 510a according to the first embodiment of the present
invention.
[0188] All the processes shown are similar to those shown in FIGS.
9 and 10. Hereinafter, differences between the two schemes are
primarily described, with no repetitive description made.
[0189] 1-5) the same as those shown in FIG. 10
[0190] 6-7) The target MME 510b transmits a context request message
to the source MME 510a to obtain EPS bearer context information of
the UE.
[0191] 7) The source MME 510a, if receiving the context request in
the state where it has transmitted a paging signal after receiving
a downlink data notification message as described above, happens to
recognize that the paging may fail.
[0192] Accordingly, the source MME 510a includes one of the
following information pieces in the context response message to be
sent to the target MME 510b and transmits the same.
TABLE-US-00009 TABLE 9 i) Indication to simply inform occurrence of
problem in paging downlink data notification for the UE has been
received paging for the UE is underway target MME 510b requires
paging or user plane bearer setup This information may be direct or
may be transmitted in various forms of implicit information so that
target MME 510b may recognize the same ii) Information necessary to
trigger active behavior of target MME 510b Additionally, source MME
510a may transmit information necessary for target MME 510b to
directly perform paging or information necessary for user plane
bearer setup (for example, information pieces included in the
downlink data notification) iii) In CSFB MT call scenario, source
MME 510a receives a paging request from MSC, and considering this
situation, source MME 510a transmits to target MME 510b information
indicating whether the call for current paging is CS (circuit
switching) call or PS (packet switching) call also. Besides,
information received from MSC may be sent as well. iv) Source MME
510a requests target MME 510b not to perform S-GW reselection (or
relocation). S-GW swapping may occur during TAU proce- dure, e.g.,
due to load balancing. As such, in case ME with downlink data
relocates to a new MME during paging, if S-GW swapping happens, a
reception call has a high chance of failure. This is to prevent
possible S-GW swapping.
[0193] 8) Then, the source MME 510a, even when not receiving a
response from the UE until the paging timer, e.g., the T3423 timer,
expires, {circumflex over (1)} does not re-transmit a paging
signal, {circumflex over (2)} nor does the source MME 510a send a
message for the paging failure (see TS 29.274, Downlink Data
Notification Failure Indication) to the S-GW 520. According to the
prior art, the source MME 510a is able to conduct a paging
re-transmission policy, and in case the S-GW 520 receives a message
for paging failure, it deletes the downlink data buffered for the
UE. The above is to prevent this.
[0194] In a more active scheme, the source MME 510a may transmit a
downlink data handling request including one of the following
information pieces to the S-GW 520.
TABLE-US-00010 TABLE 10 Request to maintain buffering the downlink
data request to re-transmit downlink data notification after
recognizing target MME 510b
[0195] Process 8) above may be performed in conjunction with other
processes without bothered by the order as shown.
[0196] 9) similar to the process shown in FIG. 10.
[0197] 10) The target MME 510b transmits a context acknowledgement
message to the source MME 510a. In this case, the target MME 510b
may include in the context acknowledgement message information
relating to paging handling such as information to request the
source MME 510a to cancel or stop the existing paging. After
receiving this message, the source MME 510a may send a downlink
data handling request message to the S-GW 520 as in process 8)
above.
[0198] 11-17) similar to the process shown in FIG. 10.
[0199] FIG. 12 is a view illustrating an exemplary TAU (Tracking
Area Update) procedure according to a second embodiment of the
present invention.
[0200] FIG. 12 illustrates a scheme that may be conducted by the
target MME 510b according to the second embodiment of the present
invention. That is, according to the second embodiment, the target
MME 510b may immediately transmit a paging signal.
[0201] All the processes shown are similar to those shown in FIGS.
9 to 11, and accordingly, differences between the two schemes are
primarily described, with no repetitive description made.
[0202] 1-8) similar to each process shown in FIG. 11.
[0203] 9a-9b) as in process 7) of FIG. 11, when receiving a context
response, the target MME 510b immediately performs paging if
recognizing a problematic situation (where the source MME 510a has
been transmitting a paging signal to the UE or there is downlink
data for the UE).
[0204] In this case, various schemes may come along to perform
paging.
[0205] As a first scheme, the target MME 510b immediately creates a
TAI list for the UE 100 and transmits paging signals to all the
eNodeBs included in the list. Of course, even according to the
prior art, the MME may create a TAI list during a TAU procedure,
includes the list in a TAU accept message, and sends the same to
the UE while transmitting paging signals to all the eNodeBs in the
list. However, according to the second embodiment of the present
invention, the target MME 510b recognizes a problematic situation
and conducts paging immediately when receiving the context response
message, thus advancing the time of paging, which makes the present
invention distinct from the prior art.
[0206] As a second scheme, the target MME 510b may know which
eNodeB it has been through from the TAU request message, i.e., in
the coverage of which eNodeB the UE is in. Accordingly, rather than
sending paging signals to all the eNodeBs in the TAI list, the
target MME 510b may transmit a paging signal only to a
corresponding eNodeB.
[0207] As a third scheme, the target MME 510b may have information
regarding more exact location of the UE, such as the cell ID of the
UE, from the TAU request message. Accordingly, the target MME 510b
may add a specific indication or cell ID information to a paging
signal that is to be sent to a corresponding eNodeB rather than
sending paging signals to all the eNodeBs in the TAI list, so that
the paging signal is sent to the corresponding cell only.
[0208] Meanwhile, when receiving the paging signal, the UE 100 may
conduct an RRC connection configuration procedure or transmit a
service request message as shown in FIGS. 15 and 16.
[0209] Procedures 9a) and 9b) above may be done together with other
processes.
[0210] 10-17) similar to the process shown in FIG. 11.
[0211] FIG. 13 is a view illustrating an exemplary TAU (Tracking
Area Update) procedure according to a third embodiment of the
present invention.
[0212] FIG. 13 illustrates a scheme that may be performed by the
target MME 510b according to the third embodiment of the present
invention. The target MME 510b may send a request for downlink data
notification to the S-GW 520.
[0213] All of the processes shown are similar to those shown in
FIGS. 9 to 12. The description thus focuses on the differences
between the two schemes, with similar processes skipped
therefrom.
[0214] 1-8) similar to those shown in FIGS. 11 to 13.
[0215] 9a) as in process 7) of FIG. 11, when receiving a context
response, the target MME 510b may recognize a problematic situation
(where the source MME 510a has been sending a paging signal to the
UE or there is downlink data for the UE).
[0216] 10) similar to the process shown in FIG. 12.
[0217] 11) the target MME 510b transmits a bearer modification
request message to the S-GW 520. In this case, the target MME 510b
has recognized the problematic situation as described above, and
thus the target MME 510b includes in the bearer modification
request message information indicating the problematic situation or
information requesting to re-transmit a downlink data
notification.
[0218] Then, the S-GW 520 may re-transmit the downlink data
notification message to the target MME 510b. Further, the S-GW 520
may conduct a subsequent procedure and a task for organizing the
downlink data notification message sent from the source MME 510a
(for example, performing an internal procedure to cancel or stop
the previous paging or sending a message for paging canceling or
stopping to the source MME 510a).
[0219] When receiving the downlink data notification message from
the S-GW 520, the target MME 510b may conduct a procedure for
paging. Or, according to a combination of other embodiments of the
present invention, the target MME 510b may conduct paging
optimization or create and transmit a TAU accept message including
specific information or a message for user plane bearer setup.
[0220] 12) the S-GW 520 transmits a bearer modification request
response message to the target MME 510b. In this case, the bearer
modification request response message may contain information
indicating to advance the time of user plane bearer setup. This
information may have influence when the target MME 510b creates a
message to be sent to the UE 100, and if needed, additional
information used to for user plane bearer setup may be transmitted
together. Or, the information included in the downlink data
notification may be additionally included.
[0221] 13) the target MME 510b may register the UE's new location
in the HSS 590. In this case, some of what has been mentioned above
may be stored in the HSS 590.
[0222] 13-17) similar to the process shown in FIG. 11.
[0223] FIG. 14 is a view illustrating an exemplary TAU (Tracking
Area Update) procedure according to a fourth embodiment of the
present invention.
[0224] FIG. 14 illustrates a scheme that may be conducted by the
target MME 510b according to the fourth embodiment of the present
invention. The target MME 510b may transmit an indication of
transmission of a service request to the UE.
[0225] Most of the processes shown are similar to those shown in
FIGS. 9 to 13. The description focuses on the differences between
the two schemes, with similar processes skipped therefrom.
[0226] 1-8) similar to the processes shown in FIGS. 11 to 13.
[0227] 9a) as in process 7) of FIG. 11, when receiving a context
response, the target MME 510b may recognize a problematic situation
(where the source MME 510a has been sending a paging signal to the
UE or there is downlink data for the UE).
[0228] 9b) then, the source MME 510a may send to the UE 100 an
indication including one of the following information pieces
independently or in conjunction with several combinations of the
embodiments of the present disclosure. Although in the drawings the
indication is in the form of a new NAS (Non-Access Stratum)
message, the indication may be included and transmitted in a TAU
accept message.
TABLE-US-00011 TABLE 11 should immediately perform user plane
bearer setup like service request should be conducted in response
to paging information regarding, upon paging response, whether to
send a service request (for receiving general PS data) or an
extended service request (for CSFB (Circuit Switch-Fallback) MT
call) call type information indicating which one of a user plane
bearer setup procedure for CS call and a user plane bearer setup
procedure for PS call is needed
[0229] The above process may be conducted in conjunction with a TAU
procedure.
[0230] Then, the UE 100 may prepare for a subsequent procedure
based on the information shown in Table 11. Accordingly, the
subsequent procedure may be very quickly done.
[0231] 10-15) similar to the process shown in FIG. 11.
[0232] 16) the target MME 510b transmits a TAU accept message.
[0233] The TAU accept message may include an indication as provided
in process 9b as described above. The indication included in the
TAU accept message may be, e.g., Active flag as described
above.
[0234] The active flag is the one that used to be included in the
TAU request message. According to an embodiment of the present
invention, the same may be included in a TAU accept message. The
target MME 510b includes the active flag in the TAU accept message
and transmits the same, so that the UE may immediately perform a
user plane bearer setup procedure.
[0235] FIG. 15 is a view illustrating an exemplary TAU (Tracking
Area Update) procedure according to a fifth embodiment of the
present invention.
[0236] FIG. 15 illustrates a scheme that may be performed by the
target MME 510b according to the fifth embodiment of the present
invention. The target MME 510b may request the target eNodeB 200b
to set up a user plane bearer.
[0237] 1-10) similar to each process shown in FIGS. 11 to 14.
[0238] 10a) as in process 7) of FIG. 11, when receiving a context
response, the target MME 510b may recognize a problematic situation
(where the source MME 510a has been transmitting a paging signal to
the UE or there is downlink data for the UE). Then, the target MME
510b sends an initial context setup request to the target eNodeB
200b for performing user plane bearer setup. In this case, as shown
in FIG. 12, with the recognition, the target MME 510b may
immediately perform paging.
[0239] 10b) the target eNodeB 200b configures a radio section for a
user plane bearer through a process for RRC connection setup. That
is, the target eNodeB 200b may enable RRC connection setup to be
triggered by transmitting a higher level signal to the UE 100. Or,
the target eNodeB 200b may perform RRC connection setup by
transmitting an RRC connection reconfiguration message to the UE
100 and receiving an RRC reconfiguration complete message from the
UE 100. Or, the target eNodeB 200b may perform RRC connection setup
by transmitting an RRC-based radio bearer setup message to the UE
100 and receiving an RRC-based radio bearer setup complete message
from the UE 100. Or, as shown in FIG. 12, the target MME 510b may
perform a paging procedure immediately after the recognition, and
the target eNodeB 200b may receive the paging signal and transfer
the same to the UE 100, allowing RRC connection setup to be
triggered. Then, the UE 100 may transmit an RRC connection request
message to the target eNodeB 200b, and the target eNodeB 200b may
transmit an RRC connection setup message to the UE 100, and the UE
100 may transmit an RRC connection setup complete message to the
target eNodeB 200b. RRC connection setup may be done so.
[0240] The UE 100 may perform an RRC connection setup procedure
when receiving a higher level signal or paging signal from the
target eNodeB 200b.
[0241] 10c) subsequently, the target eNodeB 200b transmits an
initial context setup response message to the target MME 510b.
[0242] 11-17) similar to each process shown in FIGS. 11 to 14.
[0243] FIG. 16 is a view illustrating an exemplary TAU (Tracking
Area Update) procedure according to a sixth embodiment of the
present invention.
[0244] FIG. 16 illustrates a scheme that may be performed by the UE
100 according to the sixth embodiment of the present invention.
[0245] 1-15) similar to each process shown in FIGS. 11 to 15.
[0246] 16) as in process 7) of FIG. 11, when receiving a context
response, the target MME 510b may recognize a problematic situation
(where the source MME 510a has been transmitting a paging signal to
the UE or there is downlink data for the UE). Then, the target MME
510b transmits a TAU accept message to the UE 100.
[0247] The TAU accept message may contain the information shown in
Table 11. Alternatively, the information in Table 11 may be
transmitted in a new separate NAS message, rather than included in
the TAU accept message. The use of the new NAS message
advantageously allows the UE 100 to start user plane bearer setup
relatively earlier because the UE 100 may receive the information
earlier. The benefits that come from the method in which
information as shown in Table 11 is contained and transmitted in
the TAU accept message would not change the procedure according to
the prior art.
[0248] 17) similar to the processes shown in FIGS. 11 to 15.
[0249] 18) when receiving information indicating a request for user
plane bearer setup, the UE 100 transmits a service request message
to the target eNodeB 200b. As per the prior art, the UE 100 does
not receive information requesting user plane bearer setup from a
network during a TAU process or as a result of a TAU process. In
other words, the UE 100 does not attempt to request a service,
while according to an embodiment as shown in FIG. 16, it can be
made possible. The service request message is an NAS-based message.
When receiving the service request message, the target eNodeB 200b
includes it in an initial UE message (i.e., Initial UE Message) and
transmits the same to the target MME 510b.
[0250] 19) similar to the processes shown in FIGS. 11 to 15.
[0251] 20) the target MME 510b transmits an initial context setup
request message to the target eNodeB 200b to perform user plane
bearer setup.
[0252] 21) the target eNodeB 200b and the UE 100 configure a radio
section for user plane bearer setup through a process for RRC
connection setup. To that end, the target eNodeB 200b transmits an
RRC-based radio bearer setup message to the UE 100 and receives an
RRC-based radio bearer setup complete message from the UE 100. Or,
the UE 100 transmits an RRC connection request message to the
target eNodeB 200b, and the target eNodeB 200b transmits an RRC
connection setup message to the UE 100, and the UE 100 transmits a
connection setup complete message to the target eNodeB 200b. RRC
connection setup is done so.
[0253] 22-24) similar the processes shown in FIGS. 11 to 15.
[0254] Then, the downlink data buffered in the S-GW 520 may be
transferred to the UE 100 via the target eNodeB 200b.
[0255] FIG. 17 is a view illustrating a TAU (Tracking Area Update)
procedure according to a seventh embodiment of the present
invention.
[0256] FIG. 17 illustrates a scheme that may be performed by the
S-GW 520 according to the seventh embodiment of the present
invention.
[0257] 1-7) similar to each process shown in FIGS. 11 to 15.
[0258] 8) the source MME 510a, even when subsequently failing to
receive a response from the UE until the paging timer, e.g., T3423
timer, expires, .quadrature. does not re-transmit a paging signal,
.quadrature. nor does the source MME 510a send a message regarding
the paging failure to the S-GW 520. According to the prior art, the
source MME 510a may perform a paging re-transmission policy, and
when receiving a message regarding paging failure, the S-GW 520
deletes the downlink data buffered for the UE. The above prevents
this.
[0259] In a more active method, the source MME 510a may transmit to
the S-GW 520 a downlink data handling request message including one
or more of a request for keeping buffering the downlink data and a
request for re-transmitting a downlink data notification after
recognizing the target MME 510b.
[0260] Process 8) above may be performed in conjunction with other
processes without bothered by the order as shown.
[0261] Then, the S-GW 520 keeps buffering the downlink data and
re-transmits the downlink data notification to the target MME 510b.
When receiving the request from the target MME 510b, the S-GW 520,
even receiving a notification of paging failure from the target MME
510b, does not discard but may maintain the buffered downlink
data.
[0262] 9) similar to the process shown in FIG. 10.
[0263] 11) as in process 7) of FIG. 11, when receiving a context
response, the target MME 510b may recognize a problematic situation
(where the source MME 510a has been transmitting a paging signal to
the UE or there is downlink data for the UE). Then, the target MME
510b transmits a bearer modification request message to the S-GW
520. The bearer modification request message may contain
information indicating the problematic situation or information
requesting re-transmission of the downlink data notification.
[0264] 11a) then, the S-GW 520 may re-transmit the downlink data
notification message to the target MME 510b. Further, the S-GW 520
may organize or perform a subsequent process on the downlink data
notification message sent to the source MME 510a (e.g., performing
an internal procedure to cancel or stop the previous paging or
transmitting a message regarding canceling or stopping the paging
to the source MME 510a).
[0265] When receiving the downlink data notification message from
the S-GW 520, the target MME 510b may perform a procedure for
paging, or according to a combination of the embodiments of the
present invention, may conduct paging optimization or create a TAU
accept message containing specific information or a message for
user plane bearer setup and send the same.
[0266] 11 b) the target MME 510b transmits a downlink data
notification acknowledgement message.
[0267] 12) the S-GW 520 transmits a bearer modification response
message to the target MME 510b. The bearer modification response
message may contain information triggering a procedure for
advancing the time of user plane bearer setup. This information may
have an influence when the source MME 510a creates a message to be
sent to the UE 100, and if needed, additional information for use
in user plane bearer setup may be transmitted together. Or, the
information included in the downlink data notification may be
additionally included.
[0268] 13-17) similar to each process shown in FIGS. 11 to 16.
[0269] The above embodiments assume an E-UTRAN TAU procedure
without a change of responsible S-GW, and the description thereof
may be expanded to the situation where several TAU procedures are
performed according to the prior art or to other access
networks/core networks such as RAU/LAU.
[0270] Further, varied or added information may be obtained by
adding new parameters/fields/information, by expanding existing
parameters/fields/information or by combining various
parameters/fields/information, or may come with a newly defined
message that has not been existent in the prior art.
[0271] The above-described embodiments may be combined with one
another. It should be appreciated by those skilled in the art that
the embodiments may be easily combined with each other, and thus,
detailed description of the combinations is skipped. Nonetheless,
it should be noted that such combinations are not excluded from the
scope of the present invention.
[0272] FIG. 18 is a view illustrating an exemplary protocol and
interfaces between a UE, an eNodeB, and an MME.
[0273] As shown in FIG. 18, the messages communicated between the
UE 100 and the eNodeB 200 are based on an RRC (Radio Resource
Control) protocol. The messages communicated between the eNodeB 200
and the MME 510 are based on an S1-AP (S1 Application Protocol).
The messages communicated between the UE 100 and the MME 510 are
based on an NAS (Non-Access Stratum) protocol. The NAS
protocol-based messages are capsulated into RRC protocol-based
messages and S1-AP-based messages and transmitted.
[0274] The embodiments described thus far may be implemented in
hardware, which is described below in connection with FIG. 19.
[0275] FIG. 19 is a block diagram illustrating the configuration of
an MTC device 100, an MME 510, and an SGSN 520 according to an
embodiment of the present invention.
[0276] As shown in FIG. 19, the UE 100 includes a storage means
101, a controller 102, and a communication unit 103. The MME 510
includes a storage means 511, a controller 512, and a communication
unit 513. Likewise, the S-GW 520 includes a storage means 521, a
controller 522, and a communication unit 523.
[0277] The storage means 101, 511, and 521 store the methods
described above in connection with FIGS. 9 to 18.
[0278] The controllers 102, 512, and 522 control the storage means
101, 511, and 521, and the communication units 103, 513, and 523.
Specifically, the controllers 102, 512, and 522 respectively
execute the methods stored in the storage means 101, 511, and 521.
The controllers 102, 512, and 522 transmit the above-described
signals through the communication units 103, 513, and 523.
[0279] Although the present invention has been shown or described
in connection with preferred embodiments thereof, the present
invention is not limited thereto, and rather, various changes or
modifications may be made thereto without departing from the scope
of the present invention defined by the following claims.
* * * * *