TECHNICAL FIELD
[0001] Embodiments of the present disclosure generally relate to the field of
telecommunication, and in particular, to methods, devices, and computer readable medium
for communication.
10 BACKGROUND
[0002] In communication systems, a handover is a process in telecommunications and
mobile communications in which a connected cellular call or a data session is transferred
from one cell site (base station) to another without disconnecting the session. Handovers
are a core element in planning and deploying cellular networks. It allows users to create
15 data sessions or connect phone calls on the move. This process keeps the calls and data
sessions connected even if a user moves from one cell site to another. During handover,
there may be expected interruptions.
SUMMARY
20 [0003] In general, example embodiments of the present disclosure provide a solution for
handling data inactivity for handover.
[0004] In a first aspect, there is provided a method for communication. The method
comprises receiving, at a terminal device and from a source network device, a configuration
of a data inactivity timer associated with the source network device. The method further
25 comprises receiving from the source network device a command to handover from the
source network device to the target network device, the terminal device being able to
connect with the target network device while maintaining a connection with the source
network device. The method also comprises in accordance with a determination that the
data inactivity timer is expired, maintaining the terminal device to be in a radio resource
30 control, RRC, connected state.
[0005] In a second aspect, there is provided a method for communication. The method
comprises transmitting, at a source network device and to a terminal device, a configuration
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of a data inactivity timer associated with the source network device. The method also
comprises transmitting to the terminal device network device a command to handover from
the source network device to the target network device, the terminal device being able to
connect with the target network device while maintaining a connection with the source
5 network device. The method further comprises in accordance with a determination that
the data inactivity timer is expired, releasing a link between the terminal device and the
source network device.
[0006] In a third aspect, there is provided a terminal device. The terminal device
comprises a processing unit; and a memory coupled to the processing unit and storing
10 instructions thereon, the instructions, when executed by the processing unit, causing the
terminal device to perform acts comprising: receiving, at the terminal device and from a
source network device, a configuration of a data inactivity timer associated with the source
network device; receiving from the source network device a command to handover from the
source network device to the target network device, the terminal device being able to
15 connect with the target network device while maintaining a connection with the source
network device; and in accordance with a determination that the data inactivity timer is
expired, maintaining the terminal device to be in a radio resource control, RRC, connected
state.
[0007] In a fourth aspect, there is provided a source network device. The source network
20 device comprises a processing unit; and a memory coupled to the processing unit and
storing instructions thereon, the instructions, when executed by the processing unit, causing
the source network device to perform acts comprising: transmitting, at the source network
device and to a terminal device, a configuration of a data inactivity timer associated with
the source network device; transmitting to the terminal device network device a command
25 to handover from the source network device to the target network device, the terminal
device being able to connect with the target network device while maintaining a connection
with the source network device; and in accordance with a determination that the data
inactivity timer is expired, releasing a link between the terminal device and the source
network device.
30 [0008] In a fifth aspect, there is provided a computer readable medium having instructions
stored thereon, the instructions, when executed on at least one processor, causing the at
least one processor to carry out the method according to any one of the first aspect, second
aspect or third aspect.
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[0009] Other features of the present disclosure will become easily comprehensible
through the following description.
BRIEF DESCRIPTION OF THE DRAWINGS
5 [0010] Through the more detailed description of some example embodiments of the
present disclosure in the accompanying drawings, the above and other objects, features and
advantages of the present disclosure will become more apparent, wherein:
[0011] Fig. 1 is a schematic diagram of a communication environment m which
embodiments of the present disclosure can be implemented;
10 [0012] Fig. 2 illustrates a signaling flow for handling data inactivity according to some
embodiments of the present disclosure;
[0013] Fig. 3 illustrates a signaling flow for handling data inactivity according to some
embodiments of the present disclosure;
[0014] Fig. 4 is a flowchart of an example method in accordance with an embodiment of
15 the present disclosure;
[0015] Fig. 5 is a flowchart of an example method in accordance with an embodiment of
the present disclosure; and
[0016] Fig. 6 is a simplified block diagram of a device that is suitable for implementing
embodiments of the present disclosure.
20 [0017] Throughout the drawings, the same or similar reference numerals represent the
same or similar element.
DETAILED DESCRIPTION
[0018] Principle of the present disclosure will now be described with reference to some
25 example embodiments. It is to be understood that these embodiments are described only
for the purpose of illustration and help those skilled in the art to understand and implement
the present disclosure, without suggesting any limitations as to the scope of the disclosure.
The disclosure described herein can be implemented in various manners other than the ones
described below.
30 [0019] In the following description and claims, unless defined otherwise, all technical and
scientific terms used herein have the same meaning as commonly understood by one of
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ordinary skills in the art to which this disclosure belongs.
[0020] As used herein, the term "network device" refers to a device which is capable of
providing or hosting a cell or coverage where terminal devices can communicate.
Examples of a network device include, but not limited to, a Node B (NodeB or NB), an
5 Evolved NodeB (eNodeB or eNB), a NodeB in new radio access (gNB) a Remote Radio
Unit (RRU), a radio head (RH), a remote radio head (RRH), a low power node such as a
femto node, a pica node, a satellite network device, an aircraft network device, and the like.
For the purpose of discussion, in the following, some example embodiments will be
described with reference to eNB as examples of the network device.
10 [0021] As used herein, the term "terminal device" refers to any device having wireless or
wired communication capabilities. Examples of the terminal device include, but not
limited to, user equipment (UE), personal computers, desktops, mobile phones, cellular
phones, smart phones, personal digital assistants (PDAs), portable computers, tablets,
wearable devices, internet of things (loT) devices, Internet of Everything (IoE) devices,
15 machine type communication (MTC) devices, device on vehicle for V2X communication
where X means pedestrian, vehicle, or infrastructure/network, or image capture devices
such as digital cameras, gaming devices, music storage and playback appliances, or Internet
appliances enabling wireless or wired Internet access and browsing and the like. In the
following description, the terms "terminal device", "communication device", "terminal",
20 "user equipment" and "UE" may be used interchangeably.
[0022] Communications discussed herein may use conform to any suitable standards
including, but not limited to, New Radio Access (NR), Long Term Evolution (LTE),
LTE-Evolution, LTE-Advanced (LTE-A), Wideband Code Division Multiple Access
(WCDMA), Code Division Multiple Access (CDMA), cdma2000, and Global System for
25 Mobile Communications (GSM) and the like. Furthermore, the communications may be
performed according to any generation communication protocols either currently known or
to be developed in the future. Examples of the communication protocols include, but not
limited to, the first generation (lG), the second generation (2G), 2.5G, 2.85G, the third
generation (3G), the fourth generation (4G), 4.5G, the fifth generation (5G) communication
30 protocols. The techniques described herein may be used for the wireless networks and
radio technologies mentioned above as well as other wireless networks and radio
technologies.
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[0023] As used herein, the singular forms "a", "an" and "the" are intended to include the
plural forms as well, unless the context clearly indicates otherwise. The term "includes"
and its variants are to be read as open terms that mean "includes, but is not limited to."
The term "based on" is to be read as "based at least in part on." The term "one
5 embodiment" and "an embodiment" are to be read as "at least one embodiment." The
term "another embodiment" is to be read as "at least one other embodiment." The terms
"first," "second," and the like may refer to different or same objects. Other definitions,
explicit and implicit, may be included below.
[0024] In some examples, values, procedures, or apparatus are referred to as "best,"
10 "lowest," "highest," "minimum," "maximum," or the like. It will be appreciated that such
descriptions are intended to indicate that a selection among many used functional
alternatives can be made, and such selections need not be better, smaller, higher, or
otherwise preferable to other selections.
[0025] To reduce handover interruption, dual active protocol stack (DAPS) handover has
15 been introduced. DAPS Handover is a handover procedure that maintains the source gNB
connection after reception of RRC message for handover and until releasing the source cell
after successful random access to the target gNB.
[0026] After receiving the DAPS handover command, the terminal device may create a
medium access control (MAC) entity for the target network device and may establish a
20 radio link control (RLC) entity and an associated logical channel for each data radio bearer
configured with DAPS. For a data radio bearer (DRB) configured with DAPS, the
terminal device may reconfigure a packet data convergence protocol (PDCP) entity with
separate security and a robust header compression (ROHC) function for the source network
device and the target network devices. The terminal device may also associate the PDCP
25 entities with the RLC entities configured by the source network device and the target
network devices, respectively. The terminal device may retain the rest configuration of
the source network device until releasing the connection with the source network device.
[0027] Further, a data inactivity timer has been introduced in long term evolution (LTE)
and new radio (NR) communication systems to fix radio resource control (RCC) state
30 mismatching problem. In legacy handover, the MAC entity is reset and the data inactivity
timer is stopped. And the data inactivity timer may not restart until the first uplink packet
is transmitted to the target network device. Therefore, the expiry of data inactivity timer
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does not happen during the legacy handover.
[0028] For DAPS handover, since the MAC entity associated with the source network
device is not reset, and a new MAC entity associated with the target network device is
established. The data inactivity timer of the MAC entity of the source network device may
5 continue running. Therefore, it is possible that data inactivity timer of the source network
device may be expired during the DAPS handover.
[0029] As the data inactivity timer configuration is still valid for the source network
device, how to handle this data inactivity timer for the source network device is not clear.
Meanwhile, a further data inactivity timer may also be configured for the target network
10 device, which will result in two data inactivity timers running for two MAC entities during
the DAPS handover.
[0030] Moreover, as listen-before-talk (LBT) monitoring may still be performed at the
MAC entity associated with the source network device, consistent LBT failure can happen
for the MAC entity associated with the source network device and the MAC entity
15 associated with the source network device, consistent LBT failure for the source network
device shall not lead to radio link failure.
[0031] Currently, if the data inactivity timer is expired, the terminal device may enter into
RRC idle state. However, this is not suitable for the DAPS handover. When the data
inactivity timer of the source network device is expired, the terminal device may enter into
20 the RRC idle state. But since the target network device is still expecting to establish
connection with the UE, it is not disable for the UE to go to IDLE mode.
[0032] In order to solve at least part of the aforementioned problems, new technologies in
handling data inactivity for handover are needed. According to embodiments of the
present disclosure, if an expiration of a data inactivity timer occurs during a handover, a
25 terminal device maintains in a RRC connected state. The terminal device releases a link
with the source network device. Further, the terminal device is able to ignore the
expiration of the data inactivity timer during the handover. In this way, the impact of data
inactivity of the source network device is properly handled. Further, it avoids the terminal
device being in RRC idle state for the target network device.
30 [0033] Fig. 1 illustrates a schematic diagram of a communication system m which
embodiments of the present disclosure can be implemented. The communication system
100, which is a part of a communication network, comprises a terminal device 310-1, a
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terminal device 110-2, ... , a terminal device 110-N, which can be collectively referred to
as "terminal device(s) 110." The number N can be any suitable integer number.
[0034] The communication system 100 further comprises network terminal device 120-1,
a network device 120-2, ... , a network device 120-M, which can be collectively referred to
5 as "network device(s) 120." The number M can be any suitable integer number. In the
communication system 100, the network devices 120 and the terminal devices 110 can
communicate data and control information to each other. Only for the purpose of
illustrations, the network device 120-1 can be regarded as a source network device and the
network device 120-2 can be regarded as a target network device. The numbers of
10 terminal devices and network devices shown in Fig. 1 are given for the purpose of
illustration without suggesting any limitations.
[0035] Communications in the communication system 100 may be implemented
according to any proper communication protocol(s), comprising, but not limited to, cellular
communication protocols of the first generation (1G), the second generation (2G), the third
15 generation (3G), the fourth generation (4G) and the fifth generation (5G) and on the like,
wireless local network communication protocols such as Institute for Electrical and
Electronics Engineers (IEEE) 802.11 and the like, and/or any other protocols currently
known or to be developed in the future. Moreover, the communication may utilize any
proper wireless communication technology, comprising but not limited to: Code Divided
20 Multiple Address (CDMA), Frequency Divided Multiple Address (FDMA), Time Divided
Multiple Address (TDMA), Frequency Divided Duplexer (FDD), Time Divided Duplexer
(TDD), Multiple-Input Multiple-Output (MIMO), Orthogonal Frequency Divided Multiple
Access (OFDMA) and/or any other technologies currently known or to be developed in the
future.
25 [0036] Embodiments of the present disclosure will be described in detail below.
Reference is first made to Fig. 2, which shows a signaling chart illustrating process 200
among network devices according to some example embodiments of the present disclosure.
Only for the purpose of discussion, the process 200 will be described with reference to Fig.
1. The process 200 may involve the terminal device 110-1 and the network device 120-1
30 in Fig. 1.
[0037] The source network device 120-1 transmits 2005 to the terminal device 110-1 a
configuration of a data inactivity timer associated with the source network device 120-1 to
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the terminal device ll 0-1. For example, the terminal device ll 0-1 may be configured by
RRC with a data inactivity monitoring functionality when the terminal device ll 0-1 is in
RRC_CONNECTED state. The data inactivity operation can be controlled by configuring
the data inactivity timer. The data inactivity timer may be restarted after the terminal
5 device ll 0-1 performs the data reception and/or transmission with the source network
device 120-1.
[0038] The source network device 120-1 transmits 2010 a command to handover from the
source network device 120-1 to the target network device 120-2. The terminal device
ll0-1 may be able to connect with the target network device 120-2 while maintaining a
10 connection with the source network device 120-1. In other words, the handover may be a
DAPS handover.
[0039] If the data inactivity timer is expired, the terminal device ll0-1 maintains 2015 the
RRC connected state. In some embodiments, if the data inactivity timer is expired, the
lower layer (for example, the MAC layer) may inform the RRC layer the expiration of the
15 data inactivity timer, for example, by transmitting an indication of the expiration. The
terminal device ll0-1 may determine whether the terminal device ll0-1 has accessed to the
target network device 120-2. For example, if the terminal device ll0-1 has not accessed
to the target network device 120-2, the terminal device ll0-1 may ignore 2020 the
expiration of the data inactivity timer and maintain itself in the RRC connected state.
20 [0040] Alternatively or in addition, the terminal device ll0-1 may release 2025 a link
between the source network device 120-1 and the terminal device ll 0-1. For example, the
terminal device ll0-1 may suspend the transmission of all DRBs with the source network
device 120-1. In addition, the terminal device ll0-1 may reset the MAC entity associated
with the source network device 120-1. In some embodiments, if the terminal device ll 0-1
25 does not access to the target network device 120-2, the terminal device ll0-1 may keep the
RRC configuration of the source network device 120-1. Alternatively or in addition, the
terminal device ll0-1 may stop 2030 the communication on a link between the source
network device 120-1 and the terminal device ll 0-1.
[0041] In some embodiments, the data inactivity timer may be expired after the terminal
30 device 110-1 succeeds in accessing to the target network device 120-2. In this situation,
the terminal device 110-1 may also stop 2025 the communication on the link between the
source network device 120-1 and the terminal device ll 0-1. The terminal device ll 0-1
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may release 2030 a link between the source network device 120-1 and the terminal device
110-1. Further, the terminal device 110-1 may release the RRC configuration of the
source network device 120-1. For example, the terminal device ll0-1 may reset the MAC
entity associated with the source network device 120-1 and the MAC configuration
5 associated with the source network device 120-1. For each DAPS bearer, the terminal
device ll0-1 may release the RLC entity associated with the source network device 120-1
and reconfigure the PDCP entity to release DAPS.
[0042] In some embodiments, if the data inactivity timer is expired after the terminal
device ll0-1 succeeds in accessing to the target network device 120-2, the terminal device
10 ll0-1 may ignore the expiration of the data inactivity timer and maintain itself in the RRC
connected state.
[0043] In other embodiments, the data inactivity timer associated with the source network
device 120-1 may be released. For example, the source network device 120-1 may
transmit an indication to the terminal device ll 0-1. The indication may be transmitted via
15 the RRC message before the configuration of the DAPS handover. The indication may be
used to release the data inactivity timer. The terminal device ll0-1 may release 2040 the
data inactivity timer based on the indication. Alternatively, the data inactivity timer may
be released upon an implicit indication. For example, if the RRC message of the handover
is received, the terminal device ll0-1 may release 2040 the data inactivity timer.
20 [0044] Alternatively, the source network device 120-1 may transmit a further
configuration of the data inactivity timer to the terminal device ll0-1. The further
configuration may indicate an updated duration of the data inactivity timer. The terminal
device ll 0-1 may extend 2050 a duration of the data inactivity timer based on the further
configuration. For example, the extended duration may be longer than T304.
25 [0045] Alternatively, after the terminal device ll0-1 succeeds in random accessing to the
target network device 120-1, a further data inactivity timer of the target network device
120-2 may be expired as well. Reference is made to Fig. 3, which shows a signaling chart
illustrating process 300 among network devices according to some example embodiments
of the present disclosure. Only for the purpose of discussion, the process 300 will be
30 described with reference to Fig. 1. The process 300 may involve the terminal device
ll 0-1 and the network device 120-1 in Fig. 1.
[0046] The source network device 120-1 may transmit 3005 a command to handover from
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the source network device 120-1 to the target network device 120-2. The terminal device
110-1 may be able to connect with the target network device 120-2 while maintaining a
connection with the source network device 120-1. In other words, the handover may be a
DAPS handover.
5 [0047] The terminal device 110-1 may activate 3010 the further data inactivity timer
associated with the target network device 120-2. In some embodiments, if the further data
inactivity timer is expired, the lower layer (for example, the MAC layer) may inform the
RRC layer the expiration of the further data inactivity timer, for example, by transmitting
an indication of the expiration. The terminal device 110-1 may enter 3035 into the RRC
10 idle state after the further data inactivity timer is expired.
[0048] Alternatively, if the further data inactivity timer is expired, the terminal device
110-1 may determine 3020 whether the link between the source network device 120-1 and
the terminal device 110-1 is maintained or not. In some embodiments, if the link between
the source network device 120-1 and the terminal device 110-1 is maintained, the terminal
15 device 110-1 may ignore 3025 the expiration of the further data inactivity timer. The
further data inactivity timer may be reset 3030 at the MAC layer of the terminal device
110-1. Alternatively, if the link between the source network device 120-1 and the terminal
device 110-1 has been released, the terminal device 110-1 may enter 3035 into the RRC
idle state.
20 [0049] In other embodiments, the further data inactivity timer associated with the target
network device 120-2 may not be configured before the data inactivity timer associated
with the source network device 120-1 is released. For example, the command transmitted
3005 from the source network device 120-1 may exclude the configuration of the further
data inactivity timer.
25 [0050] According to embodiment of the present disclosure, if an expiration of the data
inactivity timer associated with the source network device occurs during a handover, the
terminal device maintains in a RRC connected state. In this way, the impact of data
inactivity of the source network device is properly handled. Further, it avoids the terminal
device being in RRC idle state for the target network device. Moreover, the impact of data
30 inactivity of the target network device is also properly handled.
[0051] Fig. 4 shows a flowchart of an example method 400 m accordance with an
embodiment of the present disclosure. Only for the purpose of illustrations, the method
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400 can be implemented at a terminal device 110-1 as shown in Fig. 1.
[0052] At block 410, the terminal device ll 0-1 receives from the source network device
120-1 a configuration of a data inactivity timer associated with the source network device
120-1 to the terminal device ll0-1. For example, the terminal device ll0-1 may be
5 configured by RRC with a data inactivity monitoring functionality when the terminal
device ll0-1 is in RRC_CONNECTED state. The data inactivity operation can be
controlled by configuring the data inactivity timer. The data inactivity timer may be
restarted after the terminal device ll0-1 performs the data reception and/or transmission
with the source network device 120-1.
10 [0053] At block 420, the terminal device ll0-1 receives a command to handover from the
source network device 120-1 to the target network device 120-2. The terminal device
ll0-1 may be able to connect with the target network device 120-2 while maintaining a
connection with the source network device 120-1. In other words, the handover may be a
DAPS handover.
15 [0054] At block 430, if the data inactivity timer is expired, the terminal device ll 0-1
maintains the RRC connected state. In some embodiments, if the data inactivity timer is
expired, the lower layer (for example, the MAC layer) may inform the RRC layer the
expiration of the data inactivity timer, for example, by transmitting an indication of the
expiration. The terminal device ll 0-1 may determine whether the terminal device ll 0-1
20 is able to access the target network device 120-2. For example, if the terminal device
ll0-1 does not access to the target network device 120-2, the terminal device ll0-1 may
ignore the expiration of the data inactivity timer and maintain itself in the RRC connected
state. Alternatively or in addition, the terminal device ll0-1 may stop the communication
on a link between the source network device 120-1 and the terminal device ll 0-1.
25 [0055] In some embodiments, if the data inactivity timer is expired, the terminal device
ll0-1 releases a link between the source network device 120-1 and the terminal device
ll0-1. For example, the terminal device ll0-1 may suspend the transmission of all DRBs
with the source network device 120-1. In addition, the terminal device ll 0-1 may reset
the MAC entity associated with the source network device 120-1. In some embodiments,
30 if the terminal device ll0-1 does not access to the target network device 120-2, the terminal
device 110-1 may keep the RRC configuration of the source network device 120-1.
[0056] In some embodiments, the data inactivity timer may be expired after the terminal
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device 110-1 succeeds in accessing to the target network device 120-2. In this situation,
the terminal device 110-1 may also stop 2025 the communication on the link between the
source network device 120-1 and the terminal device 110-1. The terminal device 110-1
may release a link between the source network device 120-1 and the terminal device 110-1.
5 Further, the terminal device 110-1 may release the RRC configuration of the source
network device 120-1. For example, the terminal device 110-1 may reset the MAC entity
associated with the source network device 120-1 and the MAC configuration associated
with the source network device 120-1. For each DAPS bearer, the terminal device 110-1
may release the RLC entity associated with the source network device 120-1 and
10 reconfigure the PDCP entity to release DAPS.
[0057] In some embodiments, if the data inactivity timer is expired after the terminal
device 110-1 succeeds in accessing to the target network device 120-2, the terminal device
110-1 may ignore the expiration of the data inactivity timer and maintain itself in the RRC
connected state.
15 [0058] In other embodiments, the data inactivity timer associated with the source network
device 120-1 may be released. For example, the source network device 120-1 may
transmit an indication to the terminal device 110-1. The indication may be transmitted via
the RRC message before the configuration of the DAPS handover. The indication may be
used to release the data inactivity timer. The terminal device 110-1 may release the data
20 inactivity timer based on the indication. Alternatively, the data inactivity timer may be
released upon an implicit indication. For example, if the RRC message of the handover is
received, the terminal device 110-1 may release the data inactivity timer.
[0059] Alternatively, the source network device 120-1 may transmit a further
configuration of the data inactivity timer to the terminal device 110-1. The further
25 configuration may indicate an updated duration of the data inactivity timer. The terminal
device 110-1 may extend a duration of the data inactivity timer based on the further
configuration. For example, the extended duration may be longer than T304.
[0060] Alternatively, after the terminal device 110-1 succeeds in random accessing to the
target network device 120-2, a further data inactivity timer of the target network device
30 120-2 may be expired as well. In some embodiments, the terminal device 110-1 may
activate the further data inactivity timer associated with the target network device 120-2.
In some embodiments, if the further data inactivity timer is expired, the lower layer (for
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example, the MAC layer) may inform the RRC layer the expiration of the further data
inactivity timer, for example, by transmitting an indication of the expiration. The terminal
device 110-1 may enter 3035 into the RRC idle state after the further data inactivity timer is
expired.
5 [0061] Alternatively, if the further data inactivity timer is expired, the terminal device
110-1 may determine whether the link between the source network device 120-1 and the
terminal device 110-1 is maintained or not. In some embodiments, if the link between the
source network device 120-1 and the terminal device 110-1 is maintained, the terminal
device 110-1 may ignore the expiration of the further data inactivity timer. The further
10 data inactivity timer may be reset at the MAC layer of the terminal device 110-1.
Alternatively, if the link between the source network device 120-1 and the terminal device
110-1 has been released, the terminal device 110-1 may enter into the RRC idle state.
[0062] In other embodiments, the further data inactivity timer associated with the target
network device 120-2 may not be configured before the data inactivity timer associated
15 with the source network device 120-1 is released. For example, the command transmitted
3005 from the source network device 120-1 may exclude the configuration of the further
data inactivity timer.
[0063] In some embodiments, the terminal device 110-1 may perform listen -before-talk
(LBT) on the link between the terminal device 110-1 and the source network device 120-1.
20 If the number of LBT failures exceeds a threshold number, if the terminal device 110-1 has
not accessed to the target network device 120-2, the terminal device 110-1 may determine
that the radio link failure occurs on the link. In other words, if the indication of consistent
LBT failures comes from the MAC entity of the source network device 120-1, the terminal
device 110-1 may consider the radio link failure to be detected. The terminal device 110-1
25 may stay in the RRC connected state. Alternatively or in addition, the terminal device
110-1 may stop the communication on a link between the source network device 120-1 and
the terminal device 110-1. The terminal device 110-1 may release a link between the
source network device 120-1 and the terminal device 110-1. For example, the terminal
device 110-1 may suspend the transmission of all DRBs with the source network device
30 120-1. In addition, the terminal device 110-1 may reset the MAC entity associated with
the source network device 120-1.
[0064] Alternatively, the terminal device 110-1 may perform the LBT on a further link
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between the terminal device ll0-1 and the source network device 120-2. If the number of
LBT failures exceeds a further threshold number, the terminal device ll0-1 may determine
that the radio link failure occurs on the further link. In other words, if the indication of
consistent LBT failures comes from the MAC entity of the target network device 120-2, the
5 terminal device ll0-1 may consider the radio link failure to be detected. In some
embodiments, the terminal device 110-1 rna y initiate a link recovery for recover the link.
[0065] Fig. 5 shows a flowchart of an example method 500 in accordance with an
embodiment of the present disclosure. Only for the purpose of illustrations, the method
500 can be implemented at a source network device 120-1 as shown in Fig. 1.
10 [0066] At block 510, the source network device 120-1 transmits to the terminal device
ll0-1 a configuration of a data inactivity timer associated with the source network device
120-1 to the terminal device ll0-1. For example, the terminal device ll0-1 may be
configured by RRC with a data inactivity monitoring functionality when the terminal
device ll0-1 is in RRC_CONNECTED state. The data inactivity operation can be
15 controlled by configuring the data inactivity timer. The data inactivity timer may be
restarted after the terminal device ll0-1 performs the data reception and/or transmission
with the source network device 120-1.
[0067] At block 520, the source network device 120-1 transmits a command to handover
from the source network device 120-1 to the target network device 120-2. The terminal
20 device ll0-1 may be able to connect with the target network device 120-2 while
maintaining a connection with the source network device 120-1. In other words, the
handover may be a DAPS handover.
[0068] In other embodiments, the further data inactivity timer associated with the target
network device 120-2 may not be configured before the data inactivity timer associated
25 with the source network device 120-1 is released. For example, the command transmitted
from the source network device 120-1 may exclude the configuration of the further data
inactivity timer.
[0069] In other embodiments, the data inactivity timer associated with the source network
device 120-1 may be released. For example, the source network device 120-1 may
30 transmit 2035 an indication to the terminal device ll 0-1. The indication may be
transmitted via the RRC message before the configuration of the DAPS handover. The
indication may be used to release the data inactivity timer. Alternatively, the data
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inactivity timer may be released upon an implicit indication.
[0070] Alternatively, the source network device 120-1 may transmit a further
configuration of the data inactivity timer to the terminal device ll0-1. The further
configuration may indicate an updated duration of the data inactivity timer.
5 [0071] Fig. 6 is a simplified block diagram of a device 600 that IS suitable for
implementing embodiments of the present disclosure. The device 600 can be considered
as a further example implementation of the terminal device llO and the network device 120
as shown in Fig. 1. Accordingly, the device 600 can be implemented at or as at least a part
of the terminal device llO or the network device 120.
10 [0072] As shown, the device 600 includes a processor 610, a memory 620 coupled to the
processor 610, a suitable transmitter (TX) and receiver (RX) 640 coupled to the processor
610, and a communication interface coupled to the TX/RX 640. The memory 620 stores
at least a part of a program 630. The TX/RX 640 is for bidirectional communications.
The TX/RX 640 has at least one antenna to facilitate communication, though in practice an
15 Access Node mentioned in this application may have several ones. The communication
interface may represent any interface that is necessary for communication with other
network elements, such as X2 interface for bidirectional communications between eNBs,
S 1 interface for communication between a Mobility Management Entity (MME)/Serving
Gateway (S-GW) and the eNB, Un interface for communication between the eNB and a
20 relay node (RN), or Uu interface for communication between the eNB and a terminal
device.
[0073] The program 630 is assumed to include program instructions that, when executed
by the associated processor 610, enable the device 600 to operate in accordance with the
embodiments of the present disclosure, as discussed herein with reference to Fig. 2 to 4.
25 The embodiments herein may be implemented by computer software executable by the
processor 610 of the device 600, or by hardware, or by a combination of software and
hardware. The processor 610 may be configured to implement various embodiments of
the present disclosure. Furthermore, a combination of the processor 610 and memory 620
may form processing means 650 adapted to implement various embodiments of the present
30 disclosure.
[0074] The memory 620 may be of any type suitable to the local technical network and
may be implemented using any suitable data storage technology, such as a non-transitory
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computer readable storage medium, semiconductor-based memory devices, magnetic
memory devices and systems, optical memory devices and systems, fixed memory and
removable memory, as non-limiting examples. While only one memory 620 is shown in
the device 600, there may be several physically distinct memory modules in the device 600.
5 The processor 610 may be of any type suitable to the local technical network, and may
include one or more of general purpose computers, special purpose computers,
microprocessors, digital signal processors (DSPs) and processors based on multicore
processor architecture, as non-limiting examples. The device 600 may have multiple
processors, such as an application specific integrated circuit chip that is slaved in time to a
10 clock which synchronizes the main processor.
[0075] Generally, various embodiments of the present disclosure may be implemented in
hardware or special purpose circuits, software, logic or any combination thereof. Some
aspects may be implemented in hardware, while other aspects may be implemented in
firmware or software which may be executed by a controller, microprocessor or other
15 computing device. While various aspects of embodiments of the present disclosure are
illustrated and described as block diagrams, flowcharts, or using some other pictorial
representation, it will be appreciated that the blocks, apparatus, systems, techniques or
methods described herein may be implemented in, as non-limiting examples, hardware,
software, firmware, special purpose circuits or logic, general purpose hardware or
20 controller or other computing devices, or some combination thereof.
[0076] The present disclosure also provides at least one computer program product
tangibly stored on a non-transitory computer readable storage medium. The computer
program product includes computer-executable instructions, such as those included in
program modules, being executed in a device on a target real or virtual processor, to carry
25 out the process or method as described above with reference to any of Figs. 4-10.
Generally, program modules include routines, programs, libraries, objects, classes,
components, data structures, or the like that perform particular tasks or implement
particular abstract data types. The functionality of the program modules may be combined
or split between program modules as desired m variOus embodiments.
30 Machine-executable instructions for program modules may be executed within a local or
distributed device. In a distributed device, program modules may be located in both local
and remote storage media.
[0077] Program code for carrying out methods of the present disclosure may be written in
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any combination of one or more programming languages. These program codes may be
provided to a processor or controller of a general purpose computer, special purpose
computer, or other programmable data processing apparatus, such that the program codes,
when executed by the processor or controller, cause the functions/operations specified in
5 the flowcharts and/or block diagrams to be implemented. The program code may execute
entirely on a machine, partly on the machine, as a stand-alone software package, partly on
the machine and partly on a remote machine or entirely on the remote machine or server.
[0078] The above program code may be embodied on a machine readable medium, which
may be any tangible medium that may contain, or store a program for use by or in
10 connection with an instruction execution system, apparatus, or device. The machine
readable medium may be a machine readable signal medium or a machine readable storage
medium. A machine readable medium may include but not limited to an electronic,
magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device,
or any suitable combination of the foregoing. More specific examples of the machine
15 readable storage medium would include an electrical connection having one or more wires,
a portable computer diskette, a hard disk, a random access memory (RAM), a read-only
memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory),
an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage
device, a magnetic storage device, or any suitable combination of the foregoing.
20 [0079] Further, while operations are depicted in a particular order, this should not be
understood as requiring that such operations be performed in the particular order shown or
in sequential order, or that all illustrated operations be performed, to achieve desirable
results. In certain circumstances, multitasking and parallel processing may be
advantageous. Likewise, while several specific implementation details are contained in
25 the above discussions, these should not be construed as limitations on the scope of the
present disclosure, but rather as descriptions of features that may be specific to particular
embodiments. Certain features that are described in the context of separate embodiments
may also be implemented in combination in a single embodiment. Conversely, various
features that are described in the context of a single embodiment may also be implemented
30 in multiple embodiments separately or in any suitable sub-combination.
[0080] Although the present disclosure has been described in language specific to
structural features and/or methodological acts, it is to be understood that the present
disclosure defined in the appended claims is not necessarily limited to the specific features
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or acts described above. Rather, the specific features and acts described above are
disclosed as example forms of implementing the claims.

WHAT IS CLAIMED IS:
1. A communication method comprising:
receiving, at a terminal device and from a source network device, a configuration of
a data inactivity timer associated with the source network device;
receiving, from the source network device, a command to handover from the source
network device to the target network device, the terminal device being able to connect with
the target network device while maintaining a connection with the source network device;
and
m accordance with a determination that the data inactivity timer is expired,
10 maintaining the terminal device to be in a radio resource control, RRC, connected state.
15
20
25
30
2. The method of claim 1, further comprising:
ignoring the expiration of the data inactivity timer.
3. The method of claim 1, further comprising:
stopping communication with the source network device; and
releasing a link between the terminal device and the source network device.
4. The method of claim 3, further comprising:
determining whether the terminal device is able to access the target network device;
in accordance with a determination that the terminal device has accessed to the
target network device, releasing a RRC configuration of the source network device; or
in accordance with a determination that the terminal device has not accessed to the
target network device, maintaining the RRC configuration of the source network device.
5. The method of claim 1, further comprising:
receiving from the source network device an indication to release the data inactivity
timer; and
releasing the data inactivity timer associated with the source network device.
6. The method of claim 1, further comprising:
releasing the data inactivity timer associated with the source network device m
accordance with the reception of the command.
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7. The method of claim 1, further comprising:
receiving from the source network device a further configuration of the data
inactivity timer; and
extending a duration of the data inactivity timer based on the further configuration.
8. The method of claim 1, further comprising:
activating, at a terminal device, a further data inactivity timer associated with a
target network device; and
10 in response to the further data inactivity timer being expired, entering into a radio
15
20
resource control, RRC, idle state.
9. The method of claim 1, further comprising:
activating a further data inactivity timer associated with the target network device;
in accordance with a determination that the further data inactivity timer is expired,
determining whether a link with the source network device is maintained; and
in accordance with a determination that the link is maintained, 1gnonng the
expiration of the further data inactivity timer.
10. The method of claim 9, further comprising:
resetting the further data inactivity timer.
11. The method of claim 9, further comprising:
in accordance with a determination that the link is released, entering into a RRC idle
25 state.
30
12. The method of claim 1, wherein the command excludes a further data inactivity
timer associated with the target network device.
13. The method of claim 1, further comprising:
performing a listen-before-talk, LBT, on a link between the terminal device and the
source network device;
in accordance with a determination that the number of LBT failures exceeds a
threshold number, determining that a radio link failure occurs on the link;
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10
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stopping communication on the link; and
releasing the link between the terminal device and the source network device.
14. The method of claim 1, further comprising:
performing a listen-before-talk, LBT, on a further link between the terminal device
and a target network device;
in accordance with a determination that the number of LBT failures exceeds a
further threshold number, determining that a radio link failure occurs on the further link;
and
initiating a recovery of the further link.
15. A communication method comprising:
transmitting, at a source network device and to a terminal device, a configuration of
a data inactivity timer associated with the source network device;
transmitting, to the terminal device network device, a command to handover from
the source network device to the target network device, the terminal device being able to
connect with the target network device while maintaining a connection with the source
network device; and
in accordance with a determination that the data inactivity timer IS expired,
20 releasing a link between the terminal device and the source network device.
25
16. The method of claim 15, further comprising:
transmitting to the terminal device an indication to release the data inactivity timer.
17. The method of claim 15, further comprising:
transmitting to the terminal network device a further configuration of the data
inactivity timer to extend a duration of the data inactivity timer.
18. The method of claim 15, wherein the command excludes a further data inactivity
30 timer associated with the target network device.
19. The method of claim 15, further comprising:
performing a listen-before-talk, LBT, on a link between the terminal device and the
source network device; and
21
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m accordance with a determination that the number of listen-before-talk, LBT,
failures on the link between the terminal device and the source network device exceeds a
threshold number, releasing the link between the terminal device and the source network
device.
20. A terminal device, comprising:
a processing unit; and
a memory coupled to the processmg unit and storing instructions thereon, the
instructions, when executed by the processing unit, causing the terminal device to perform
10 acts comprising:
receiVmg, at the terminal device and from a source network device, a
configuration of a data inactivity timer associated with the source network device;
receiving from the source network device a command to handover from the
source network device to the target network device, the terminal device being able to
15 connect with the target network device while maintaining a connection with the source
network device; and
20
25
in accordance with a determination that the data inactivity timer is expired,
maintaining the terminal device to be in a radio resource control, RRC, connected state.
21. The terminal device of claim 20, wherein the acts further comprises:
ignoring the expiration of the data inactivity timer.
22. The terminal device of claim 20, wherein the acts further comprises:
stopping communication with the source network device; and
releasing a link between the terminal device and the source network device.
23. The terminal device of claim 22, wherein the acts further comprises:
determining whether the terminal device is able to access the target network device;
in accordance with a determination that the terminal device has accessed to the
30 target network device, releasing a RRC configuration of the source network device; or
in accordance with a determination that the terminal device has not accessed to the
target network device, maintaining the RRC configuration of the source network device.
24. The terminal device of claim 20, wherein the acts further comprises:
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15
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receiving from the source network device an indication to release the data inactivity
timer; and
releasing the data inactivity timer associated with the source network device.
25. The terminal device of claim 20, wherein the acts further comprises:
releasing the data inactivity timer associated with the source network device m
accordance with the reception of the command.
26. The terminal device of claim 20, wherein the acts further comprises:
receiving from the source network device a further configuration of the data
inactivity timer; and
extending a duration of the data inactivity timer based on the further configuration.
27. The terminal device of claim 20, wherein the acts further comprises:
activating, at a terminal device, a further data inactivity timer associated with a
target network device; and
in response to the further data inactivity timer being expired, entering into a radio
resource control, RRC, idle state.
28. The terminal device of claim 20, wherein the acts further comprises:
activating a further data inactivity timer associated with the target network device;
in accordance with a determination that the further data inactivity timer is expired,
determining whether a link with the source network device is maintained; and
in accordance with a determination that the link is maintained, 1gnonng the
25 expiration of the further data inactivity timer.
30
state.
29. The terminal device of claim 28, wherein the acts further comprises:
resetting the further data inactivity timer.
30. The terminal device of claim 28, wherein the acts further comprises:
in accordance with a determination that the link is released, entering into a RRC idle
31. The terminal device of claim 20, wherein the command excludes a further data
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inactivity timer associated with the target network device.
32. The terminal device of claim 20, wherein the acts further comprises:
performing a listen-before-talk, LBT, on a link between the terminal device and the
5 source network device;
10
in accordance with a determination that the number of LBT failures exceeds a
threshold number, determining that a radio link failure occurs on the link;
stopping communication on the link; and
releasing the link between the terminal device and the source network device.
33. The terminal device of claim 20, wherein the acts further comprises:
performing a listen-before-talk, LBT, on a further link between the terminal device
and a target network device;
in accordance with a determination that the number of LBT failures exceeds a
15 further threshold number, determining that a radio link failure occurs on the further link;
and
20
initiating a recovery of the further link.
34. A source network device, comprising:
a processing unit; and
a memory coupled to the processmg unit and storing instructions thereon, the
instructions, when executed by the processing unit, causing the source network device to
perform acts comprising:
transmitting, at the source network device and to a terminal device, a
25 configuration of a data inactivity timer associated with the source network device;
30
transmitting to the terminal device network device a command to handover from
the source network device to the target network device, the terminal device being able to
connect with the target network device while maintaining a connection with the source
network device; and
in accordance with a determination that the data inactivity timer IS expired,
releasing a link between the terminal device and the source network device.
35. The source network device of claim 34, wherein the acts further comprises:
transmitting to the target network device an indication to release the data inactivity
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timer.
36. The source network device of claim 34, wherein the acts further comprises:
receiving from the source network device a further configuration of the data
5 inactivity timer to extend a duration of the data inactivity timer.
10
37. The source network device of claim 34, wherein the command excludes a further
data inactivity timer associated with the target network device.
38. The source network device of claim 34, further comprising:
performing a listen-before-talk, LBT, on a link between the terminal device and the
source network device; and
in accordance with a determination that the number of listen-before-talk, LBT,
failures on the link between the terminal device and the source network device exceeds a
15 threshold number, releasing the link between the terminal device and the source network
device.
39. A computer readable medium having instructions stored thereon, the
instructions, when executed on at least one processor, causing the at least one processor to
20 carry out the method according to any one of claims 1-14.
40. A computer readable medium having instructions stored thereon, the
instructions, when executed on at least one processor, causing the at least one processor to
carry out the method according to any one of claims 15-19.