Technical Field
The present invention relates to a communication system. The invention has
particular but not exclusive relevance to wireless communication systems and devices
thereof operating according to the 3rd Generation Partnership Project (3GPP) standards
or equivalents or derivatives thereof (including LTE-Advanced and Next Generation or
5G networks). The invention has particular, although not necessarily exclusive
relevance to transmission of small data for user equipment in inactive state.
Background Art
[0002] Recent developments of the 3GPP standards are referred to as the Long Term
[0003]
[0004]
[0005]
Evolution (LTE) of Evolved Packet Core (EPC) network and Evolved UMTS Terrestrial
Radio Access Network (E-UTRAN), also commonly referred as '4G'. In
addition, the term '5G' and 'new radio' (NR) refer to an evolving communication
technology that is expected to support a variety of applications and services. Various
details of 5G networks are described in, for example, the 'NGMN 5G White Paper'
Vl.O by the Next Generation Mobile Networks (NGMN) Alliance, which document is
available from https://www.ngmn.org/5g-white-paper.html. 3GPP intends to support
5G by way of the so-called 3GPP Next Generation (NextGen) radio access network
(RAN) and the 3GPP NextGen core network.
Under the 3GPP standards, a NodeB (or an 'eNB' in LTE, 'gNB' in 5G) is the base
station via which communication devices (user equipment or 'UE') connect to a core
network and communicate to other communication devices or remote servers. For
simplicity, the present application will use the term base station to refer to any such
base stations.
For simplicity, the present application will use the term mobile device, user device,
or UE to refer to any communication device that is able to connect to the core network
via one or more base stations.
Communication devices might be, for example, mobile communication devices such
as mobile telephones, smartphones, user equipment, personal digital assistants, laptop/
tablet computers, web browsers, e-book readers and/or the like. Such mobile (or even
generally stationary) devices are typically operated by a user. However, 3GPP
standards also make it possible to connect so-called 'Internet of Things' (loT) devices
(e.g. Narrow-Band loT (NB-IoT) devices) to the network, which typically comprise
automated equipment, such as various measuring equipment, telemetry equipment,
monitoring systems, tracking and tracing devices, in-vehicle safety systems, vehicle
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maintenance systems, road sensors, digital billboards, point of sale (POS) terminals,
remote control systems, and the like. Effectively, the Internet of Things is a network of
devices (or "things") equipped with appropriate electronics, software, sensors, network
connectivity, and/or the like, which enables these devices to collect and exchange data
with each other and with other communication devices. It will be appreciated that loT
devices are sometimes also referred to as Machine-Type Communication (MTC) communication
devices or Machine-to-Machine (M2M) communication devices.
[0006] For simplicity, the present application often refers to mobile devices in the description
but it will be appreciated that the technology described can be implemented
on any communication devices (mobile and/or generally stationary) that can connect to
a communications network for sending/receiving data, regardless of whether such
communication devices are controlled by human input or software instructions stored
mmemory.
[0007] The core network (i.e. the 'EPC' in case of LTE and '5GC' in 5G) typically hosts
[0008]
functionality for subscriber management, mobility management, charging, security,
and call/session management (amongst others), and provides connection for communication
devices to external networks, such as the Internet.
Before a UE can communicate data via a base station, it needs to perform a so-called
(contention-based) random access procedure with the base station serving the cell in
which the UE is located. Currently, in Release 15, the random access procedure is a
four-step procedure. In the first step (referred to as 'Msg1 '),the UE transmits a
Physical Random Access Channel (PRACH) preamble. If the base station detects the
preamble, the base station responds with a random access response (RAR), also known
as 'Msg2'. The RAR includes the detected preamble identifier, a time-advance
command, a temporary C-RNTI (TC-RNTI), and an uplink (UL) grant for scheduling a
Physical Uplink Shared Channel (PUSCH) transmission from the UE (referred to as
'Msg3'). The UE transmits Msg3 as scheduled and includes an identifier for contention
resolution. Upon receiving Msg3, the network transmits a contention resolution
message, also known as 'Msg4', with the contention resolution identifier. If the UE
successfully receives Msg4, and if it finds its contention resolution identifier, it sends
an acknowledgement on the Physical Uplink Control Channel (PUCCH), which
completes the four-step random access procedure.
[0009] From Release 16 of the 3GPP standards, a two-step random access procedure has
been proposed (in addition to the currently used four-step Random Access procedure).
The two-step random access is mainly intended for supporting (Ultra) Low Latency
Communications, 10ms control-plane (CP) latency, fast handover, efficient channel
access in unlicensed spectrum, and transmission of small data packets, amongst others.
As can be seen, the four-step random access procedure requires two round-trip cycles
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between the UE and the base station. The two-step random access procedure aims to
reduce latency and control-signaling overhead by using a single round trip cycle
between the UE and the base station. Effectively, this is achieved by combining the
UE's PRACH preamble (Msgl) transmission and the scheduled PUSCH transmission
(Msg3) into a single message (referred to as 'MsgA'). Similarly, the random-access
response (RAR/Msg2) from the base station to UE and the contention resolution
message (Msg4) are combined in the two-step random access procedure (and referred
to as 'MsgB ').
[0010] Following the random access procedure, the UE enters to so-called Radio Resource
[0011]
[0012]
Control (RRC) CONNECTED state and it can start sending/receiving data (both userplane
data and control-plane data) using resources allocated by (a base station of) the
network. The UE's transition between RRC states is controlled by the network (using
associated timers etc.). Typically, when a UE has no more data to send/receive, it is instructed
by the network to move to the so-called RRC IDLE state, in order to free up
network resources and to save battery at the UE' s side. Every time the UE has data to
send or receive, it needs to enter the RRC CONNECTED state again (after performing
an appropriate random access procedure with the network). Whilst generally the RRC
IDLE state is the most power efficient state, some UEs may need to transition between
RRC IDLE and RRC CONNECTED frequently which results in increasing signalling
and may adversely affect their power consumption as well.
In LTE, 3GPP attempted to address this issue in various ways, including Control-
Plane Earlier Data Transmission (CP-EDT) and User-Plane Earlier Data Transmission
(UP-EDT) which may be used by UEs in RRC IDLE state.
In case of CP-EDT, data is included in a Non-Access Stratum (NAS) container and
then put into an appropriate Common Control Channel (CCCH) RRC message. The
NAS container is forwarded to the S-GW by the MME. As the data is sent via the
Control-Plane, no Data Radio Bearer (DRB) is used. Thus, the UE remains in RRC
IDLE (unless the network instructs it to move to RRC CONNECTED). CP-EDT does
not use Access Stratum (AS) security thus the PDCP and RLC layers are not involved
in the transmission of the data (NAS container).
[0013] In case of UP-EDT, data is sent via the User-Plane, after resuming an appropriate
DRB. The data is ciphered and transmitted on the Dedicated Traffic Channel (DTCH),
multiplexed with a RRCConnectionResumeRequest in the CCCH at the MAC layer. In
this case, the base station re-activates the S1-U bearers for the UE and forwards the
data to S-GW directly.
[0014] The 3GPP NR standards introduced the so-called RRC INACTIVE state, in addition
to RRC IDLE and RRC CONNECTED. In the RRC INACTIVE state all DRBs and
Signalling Radio Bearers (SRBs) are suspended, except 'SRBO'. However the UE's
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[0015]
Ng-U and Ng-C connections are maintained (unlike in RRC IDLE), which means that
only the CCCH channel is active (for SRBO). Thus, when new data arrives from an
upper layer, it cannot be transmitted immediately. Data can only be transmitted after
performing an RRC resume procedure, which causes the UE to resume (or reconfigure)
all its DRB and SRBs. A difference compared to UP-EDT is that the DRBs are
resumed immediately upon data arrival and data can be transmitted via DRB/
DTCH/PUSCH, as appropriate.
For UEs in the RRC INACTIVE state, 3GPP intends to support certain communications
(typically, a relatively small amount of data) without the UE having to
(re-)activate/resume its RRC connection with the network. This functionality is
referred to as 'small data transmission' and it is applicable to a number of traffic types,
such as infrequent transmissions, short data bursts, and low throughput transmissions.
Some of the benefits associated with small data transmission include a reduction in
signalling overhead associated with RRC state transitions, lower battery consumption,
and lower latency (compared to the case when the UE needs to transition into RRC
connected state).
[0016] The motivation behind small data transmissions for UEs in INACTIVE state is
described in 3GPP work item no. RP-193252. In summary, the small data transmission
feature allows a UE to remain in the RRC_INACTIVE state for certain downlink
(mobile terminated, 'MT') and uplink (mobile originated, 'MO') data transmissions. In
other words, the UE does not need to resume its RRC connection (i.e. move to the
RRC CONNECTED state) for data transmission and it does not need to subsequently
release the connection (back to RRC INACTIVE state) after data transmission, thereby
the UE 3 can avoid some of the associated drawbacks (e.g. increased power consumption
and signalling overhead).
[0017] In Rel-17 small and infrequent data traffic will be allowed in INACTIVE state in the
[0018]
following use cases (amongst others):
- Smartphone applications:
traffic from Instant Messaging services (e.g. Whatsapp, QQ, Wechat etc.);
heart-beat/keep-alive traffic from instant messaging/email clients and similar applications;
· push notifications from various applications;
- Non-smartphone applications:
traffic from wearables (periodic positioning information etc.);
sensors (Industrial Wireless Sensor Networks transmitting temperature, pressure
readings periodically or in an event triggered manner etc.); and
· smart meters and smart meter networks sending periodic meter readings.
Signalling overhead from INACTIVE state UEs for small data packets is a general
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problem and will become a critical issue with more UEs in NR not only for network
performance and efficiency but also for the UE battery performance. In general, any
device that has intermittent small data packets in INACTIVE state will benefit from
enabling small data transmission in INACTIVE.
[0019] Although some of the key enablers for small data transmission in NR have already
[0020]
been specified in Rel-15 and Rel-16 (such as the RRC INACTIVE state, 2-step/4-step
random access, and configured grant type-1 ), there are still a number of issues and objectives
that need to be addressed, for example:
In case of UL small data transmissions using 2-step or 4-step random access:
· There is no procedure to enable user-plane (UP) data transmission for small
data packets from a UE in RRC INACTIVE state (e.g. using MsgA of the 2-step
random access procedure or Msg3 of the 4-step random access procedure);
· Need to enable flexible payload sizes larger than the Rel-16 CCCH message
size currently defined for RRC INACTIVE state for MsgA and Msg3 in order to
support UP data transmission in UL;
· Need to define context fetch and data forwarding procedures (with and without
anchor relocation) in RRC INACTIVE state for random access based solutions;
· In case of transmission of UL data on pre-configured PUSCH resources (using the
so-called 'configured grant type 1 '):
· There is no procedure for small data transmission over configured grant type 1
resources in RRC INACTIVE state; and
· Configured grant type1 resources are not configured for UL small data
transmission in RRC INACTIVE state.
Summary of Invention
Accordingly, preferred example embodiments of the present invention aim to provide
methods and apparatus which address or at least partially deal with one or more of the
above issues.
[0021] Although for efficiency of understanding for those of skill in the art, the invention
will be described in detail in the context of a 3GPP system (UMTS, LTE, NR), the
principles of the invention can be applied to other systems in which communication
devices or User Equipment (UE) access a core network using a radio access
technology.
[0022] In one example aspect, the invention provides a method performed by a user
equipment (UE) for small data transmission in Radio Resource Control (RRC) Inactive
state, the method comprising: receiving information configuring small data transmissions
via a control-plane; determining, whilst the UE is in the RRC Inactive state,
whether there is uplink data to be sent as a small data transmission; generating an RRC
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message comprising said small data transmission; and transmitting said RRC message
comprising said small data transmission using a Signalling Radio Bearer (SRB)
provided via a Common Control Channel (CCCH).
[0023] In another example aspect, the invention provides a method performed by a user
[0024]
[0025]
[0026]
[0027]
equipment (UE) for small data transmission in Radio Resource Control (RRC) Inactive
state, the method comprising: receiving information configuring identifying a Data
Radio Bearer (DRB) to be used for small data transmissions in the RRC Inactive state;
determining, whilst when the UE is in the RRC Inactive state, whether there is uplink
data to be sent as a small data transmission; processing the uplink data to form a small
data transmission and adding information identifying the UE; and transmitting said
small data transmission and said information identifying the UE using a Data Radio
Bearer (DRB) based on the received information the identified DRB.
In one example aspect, the invention provides a method performed by a communication
apparatus of a radio access network for communicating with a user equipment
(UE) for small data transmission in a Radio Resource Control (RRC) Inactive state, the
method comprising: transmitting information configuring small data transmissions via
a control-plane; and receiving, from the UE whilst the UE is in the RRC Inactive state,
an RRC message comprising a small data transmission using a Signalling Radio Bearer
(SRB) provided via a Common Control Channel (CCCH).
In one example aspect, the invention provides a method performed by a communication
apparatus of a radio access network for communicating with a user equipment
(UE) for small data transmission in Radio Resource Control (RRC) Inactive state, the
method comprising: transmitting information configuring small data transmissions in
the RRC Inactive state; and receiving, from the UE whilst the UE is in the RRC
Inactive state, a small data transmission and information identifying the UE using a
Data Radio Bearer (DRB) based on the transmitted information.
In one example aspect, the invention provides a user equipment (UE) for small data
transmission in Radio Resource Control (RRC) Inactive state, the UE comprising:
means for receiving information configuring small data transmissions via a controlplane;
means for determining, whilst the UE is in the RRC Inactive state, whether there
is uplink data to be sent as a small data transmission; means for generating an RRC
message comprising said small data transmission; and means for transmitting said
RRC message comprising said small data transmission using a Signalling Radio Bearer
(SRB) provided via a Common Control Channel (CCCH).
In one example aspect, the invention provides a user equipment (UE) for small data
transmission in Radio Resource Control (RRC) Inactive state, the UE comprising:
means for receiving information configuring small data transmissions in the RRC
Inactive state; means for determining, when the UE is in the RRC Inactive state,
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whether there is uplink data to be sent as a small data transmission; means for
processing the uplink data to form a small data transmission and adding information
identifying the UE; and means for transmitting said small data transmission and said
information identifying the UE using a Data Radio Bearer (DRB) based on the
received information.
[0028] In another example aspect, the invention provides a communication apparatus of a
radio access network for communicating with a user equipment (UE) for small data
transmission in a Radio Resource Control (RRC) Inactive state, the communication
apparatus comprising: means for transmitting information configuring small data transmissions
via a control-plane; and means for receiving, from the UE whilst the UE is in
the RRC Inactive state, an RRC message comprising a small data transmission using a
Signalling Radio Bearer (SRB) provided via a Common Control Channel (CCCH).
[0029] In yet another example aspect, the invention provides a communication apparatus of
[0030]
[0031]
[0032]
a radio access network for communicating with a user equipment (UE) for small data
transmission in Radio Resource Control (RRC) Inactive state, the communication
apparatus comprising: means for transmitting information configuring small data transmissions
in the RRC Inactive state; and means for receiving, from the UE whilst the
UE is in the RRC Inactive state, a small data transmission and information identifying
the UE using a Data Radio Bearer (DRB) based on the transmitted information.
Example aspects of the invention extend to corresponding systems, apparatus, and
computer program products such as computer readable storage media having instructions
stored thereon which are operable to program a programmable processor to
carry out a method as described in the example aspects and possibilities set out above
or recited in the claims and/or to program a suitably adapted computer to provide the
apparatus recited in any of the claims.
Each feature disclosed in this specification (which term includes the claims) and/or
shown in the drawings may be incorporated in the invention independently of (or in
combination with) any other disclosed and/or illustrated features. In particular but
without limitation the features of any of the claims dependent from a particular independent
claim may be introduced into that independent claim in any combination or
individually.
Brief Description of Drawings
Example embodiments of the invention will now be described, by way of example,
with reference to the accompanying drawings in which:
[fig.1]Figure 1 illustrates schematically a mobile (cellular or wireless) telecommunication
system to which example embodiments of the invention may be applied;
[fig.2]Figure 2 is a block diagram of a User Equipment (UE) forming part of the
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[0033]
[0034]
[0035]
system shown in Figure 1;
[fig.3]Figure 3 is a block diagram of a base station forming part of the system shown in
Figure 1;
[fig.4 ]Figure 4 is a block diagram of a core network node entity forming part of the
system shown in Figure 1;
[fig.5]Figure 5 is a schematic overview of the layers involved in small data
transmission in accordance with a first exemplary method;
[fig.6]Figure 6 is a schematic flowchart illustrating the main steps for small data
transmission in accordance with the first exemplary method;
[fig.7]Figure 7 is a schematic overview of the layers involved in small data
transmission in accordance with a second exemplary method;
[fig.8]Figure 8 is a schematic flowchart illustrating the main steps for small data
transmission in accordance with the second exemplary method;
[fig.9]Figure 9 illustrates schematically some modifications of the first exemplary
method; and
[fig.10]Figure 10 illustrates schematically some modifications of the first exemplary
method.
Description of Embodiments
Overview
Figure 1 schematically illustrates a mobile (cellular or wireless) telecommunication
system 1 to which example embodiments of the present invention are applicable.
In this network, users of mobile devices 3 (UEs) can communicate with each other
and other users via respective base stations 5 and a core network 7 using an appropriate
3GPP radio access technology (RAT), for example, an E-UTRA and/or 5G RAT. It
will be appreciated that a number of base stations 5 form a (radio) access network or
(R)AN. As those skilled in the art will appreciate, whilst one mobile device 3 and one
base station 5 are shown in Figure 1 for illustration purposes, the system, when Implemented,
will typically include other base stations and mobile devices (UEs).
Each base station 5 controls one or more associated cells (either directly or via other
nodes such as home base stations, relays, remote radio heads, distributed units, and/or
the like). A base station 5 that supports E-UTRA/4G protocols may be referred to as an
'eNB' and a base station 5 that supports Next Generation/50 protocols may be referred
to as a 'gNBs'. It will be appreciated that some base stations 5 may be configured to
support both 4G and 5G, and/or any other 3GPP or non-3GPP communication
protocols.
[0036] The mobile device 3 and its serving base station 5 are connected via an appropriate
air interface (for example the so-called 'Uu' interface and/or the like). Neighbouring
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[0037]
[0038]
base stations 5 are connected to each other via an appropriate base station to base
station interface (such as the so-called 'X2' interface, 'Xn' interface and/or the like).
The base station 5 is also connected to the core network nodes via an appropriate
interface (such as the so-called 'Sl ', 'Nl ', 'N2', 'N3' interface, and/or the like).
The core network 7 typically includes logical nodes (or 'functions') for supporting
communication in the telecommunication system 1. Typically, for example, the core
network 7 of a 'Next Generation' I 5G system will include, amongst other functions,
control plane functions (CPFs) and user plane functions (UPFs). It will be appreciated
that the core network 7 may also include, amongst others, a Mobility Management
Entity (MME) 11 and a Serving Gateway (S-GW) 12. In NR networks, a so-called
Access and Mobility Management Function (AMF) may be provided instead of, or in
addition to, the MME 11. From the core network 7, connection to an external IP
network 20 (such as the Internet) may also be provided.
The system supports both legacy (i.e. four-step) and two-step random access
procedures. Certain UEs 3 may also be configured to communicate without an explicit
grant from the network, using resources allocated to configured grant type-1 communications.
[0039] The nodes of this network 1 are configured to support small data transmission
[0040]
[0041]
services for UEs 3 in RRC INACTIVE state. Such small data transmissions may be
realised either via the Control-Plane (first option) or the User-Plane (second option).
In case of the first option, the UE 3 is configured (by the network) to perform small
data transmissions via the Control-Plane. The UE 3 may be configured using an RRC
release message or an RRC suspension message (and/or the like). When there is uplink
data that can be sent as small data, the UE 3 generates an RRC message (e.g. a
'smallDataTransmission' message and/or the like) and transmits this message within
an appropriately formatted CCCH message (via the signalling radio bearer 'SRBO'
which remains active during RRC INACTIVE mode). The CCCH message containing
the small data transmission (within the RRC message) may be transmitted either via a
pre-configured PUSCH resource (if available) or using an appropriate (2-step or
4-step) random access procedure. If a random access procedure is used, the above
described CCCH message may be transferred to the network (i.e. the base station 5)
within either MsgA or Msg3.
In case of the second option, the UE 3 may be configured with a DRB for small data
transmissions. When the UE 3 is in RRC INACTIVE mode, it suspends all other DRBs
and SRBs. Therefore, any uplink data may be processed through the appropriate UserPlane
protocol of the DRB configured for small data transmissions. The data may be
transmitted either via a pre-configured PUSCH resource (if available) or by triggering
an appropriate (2-step/4-step) random access procedure. In this case the MAC layer is
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[0042]
[0043]
[0044]
[0045]
configured to add appropriate information identifying the UE 3 (e.g. 'UE ID') to the
uplink transmission.
In summary, the above described system provides a number of benefits, for example:
- efficiency and flexibility for low throughput short data bursts;
-support for efficient signalling mechanisms (e.g. signalling is less than payload);
and
- reduction in overall signalling overhead.
Mobile device
Figure 2 is a block diagram illustrating the main components of the mobile device 3
shown in Figure 1 (e.g. a mobile telephone or an loT device). As shown, the mobile
device 3 has a transceiver circuit 31 that is operable to transmit signals to and to
receive signals from a base station 5 via one or more antenna 33. The mobile device 3
has a controller 37 to control the operation of the mobile device 3. The controller 37 is
associated with a memory 39 and is coupled to the transceiver circuit 31. Although not
necessarily required for its operation, the mobile device 3 might of course have all the
usual functionality of a conventional mobile telephone (such as a user interface 35) and
this may be provided by any one or any combination of hardware, software and
firmware, as appropriate. Software may be pre-installed in the memory 39 and/or may
be downloaded via the telecommunications network or from a removable data storage
device (RMD), for example.
The controller 37 is configured to control overall operation of the mobile device 3
by, in this example, program instructions or software instructions stored within
memory 39. As shown, these software instructions include, among other things, an
operating system 41, a communications control module 43, and a small data module
45.
The communications control module 43 is operable to control the communication
between the mobile device 3 and its serving base station 5 (and other communication
devices connected to the serving base station 5, such as other user equipment, core
network nodes, etc.).
[0046] The small date module 45 is responsible for communicating small data transmissions,
which may be sent (or received) without the mobile device 3 having an active RRC
connection (for example while the mobile device 3 is in the RRC INACTIVE state).
[0047] Although not shown in Figure 2, the mobile device 3 will also typically include respective
modules corresponding to the different communication layers. These modules
may be implemented as part of the communications control module 43 and include one
or more of the following: a Non-Access Stratum (NAS) module, a Radio Resource
Control (RRC) module, a Service Data Adaptation Protocol (SDAP) module, a Packet
Data Convergence Protocol (PDCP) module, a Radio Link Control (RLC) module, a
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[0048]
[0049]
[0050]
[0051]
Medium Access Control (MAC) module, and a physical layer (PHY) module.
The RRC module is operable to generate, send and receive signalling messages
formatted according to the RRC standard. For example, such messages are exchanged
between the mobile device 3 and its serving base station 5. The RRC messages may
include, for example, messages relating to small data transmission (or reception)
including messages carrying small data transmissions and associated information. The
RRC module is also responsible for managing the mobile device's Radio Resource
Control connection with the network and its RRC mode (e.g. RRC IDLE, RRC
CONNECTED, and RRC INACTIVE).
The NAS module is operable to generate, send and receive signalling messages
formatted according to the NAS standard. For example, such messages are exchanged
between the mobile device 3 and the MME/AMF 11 (via the serving base station 5,
using the RRC module). The NAS messages may include, for example, messages
relating to registering and/or updating a tracking area (or cell) where the mobile device
3 is currently located. The NAS messages may also include small data transmissions.
Base Station
Figure 3 is a block diagram illustrating the main components of a base station 5
shown in Figure 1. As shown, the base station 5 has a transceiver circuit 51 for
transmitting signals to and for receiving signals from user equipment (such as the
mobile device 3) via one or more antenna 53, a core network interface 55 (e.g. an Sl
interface, NG-C interface, and/or the like) for transmitting signals to and for receiving
signals from the core network 7, and a base station interface 56 (e.g. an X2 interface,
Xn interface, and/or the like) for transmitting signals to and for receiving signals from
neighbouring base stations. The base station 5 has a controller 57 to control the
operation of the base station 5 in accordance with software stored in a memory 59. The
software may be pre-installed in the memory 59 and/or may be downloaded via the
telecommunication network 1 or from a removable data storage device (RMD), for
example. The software includes, among other things, an operating system 61, at least a
communications control module 63, and a small data module 65.
The communications control module 63 is responsible for handling
(generating/sending/ receiving) signalling between the base station 5 and other nodes,
such as the UE 3 and the core network nodes. Such signalling may include, for
example, control data for managing operation of the mobile device 3 (e.g. NAS, RRC,
paging, system information, and/or the like).
[0052] The small date module 65 is responsible for handling small data transmissions for the
mobile device 3 (for example while the mobile device 3 is in the RRC INACTIVE
state).
[0053] Although not shown in Figure 3, the base station 5 will also typically include a base
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station to base station interface module (e.g. X2/Xn module), an appropriate core
network interface module (which may be implemented as part of the communications
control module 43), and respective modules corresponding to the different communication
layers (e.g. RRC module, SDAP module, PDCP module, RLC module, MAC
module, and PHY module).
[0054] The base station to base station interface module is operable to generate, send and
receive signalling messages (X2/Xn messages) formatted according to the X2AP (or
XnAP) standard. The X2/Xn messages may include, for example, messages relating to
paging a mobile device 3, handover, data forwarding, transferring/fetching of UE
context (and other information relating to the mobile device 3) between neighbouring
base stations.
[0055] The core network interface module is operable to generate, send and receive
[0056]
[0057]
signalling messages formatted according to the NG-C standard (or the SlAP standard
in LTE), including messages carrying small data transmissions for the UE 3. For
example, such messages are exchanged between the base station 5 and the MME/ AMP
11 and/or the S-GW 12.
The RRC module is operable to generate, send and receive signalling messages
formatted according to the RRC standard. For example, such messages are exchanged
between the base station 5 and the mobile device 3 (and other user equipment within
the cell of the base station 5). The RRC messages may include, for example, messages
relating to small data transmission (or reception) including messages carrying small
data transmissions and associated information. The RRC module is also responsible for
managing the mobile device's Radio Resource Control connection with the network
and its RRC mode (e.g. RRC IDLE, RRC CONNECTED, and RRC INACTIVE).
Core network node
Figure 4 is a block diagram illustrating the main components of a generic core
network node (or function) shown in Figure 1, for example, the MME 11 or the S-GW
12. As shown, the core network node includes a transceiver circuit 71 which is
operable to transmit signals to and to receive signals from other nodes (including the
UE 3 and the (R)AN node 5) via a network interface 75. A controller 77 controls the
operation of the core network node in accordance with software stored in a memory
79. The software may be pre-installed in the memory 79 and/or may be downloaded
via the telecommunication network 1 or from a removable data storage device (RMD),
for example. The software includes, among other things, an operating system 81 and at
least a communications control module 83. The communications control module 83 is
responsible for handling (generating/sending/ receiving) signaling between the core
network node and other nodes, such as the UE 3, the (R)AN node 5, and other core
network nodes. The signalling may comprise, for example, NAS signalling and/or
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[0058]
small data transmissions between the mobile device 3 and the MME/ AMP 11.
Detailed description
A more detailed description will now be given of some exemplary ways in which
small data transmissions may be performed by a UE in RRC INACTIVE state.
[0059] Figure 5 is a schematic overview of the layers involved in small data transmission in
accordance with a first exemplary method, using Control-Plane signalling.
[0060] In more detail, the UE 3 is configured to perform small data transmission via the
CCCH channel, using an appropriately formatted RRC message. The RRC message
may be a dedicated (e.g. newly defined) RRC message or an RRC message adapted for
this purpose. In order to facilitate small data transmissions, the RRC layer (RRC
module) is adapted to add an appropriate UE-ID when the UE 3 is transmitting small
data. In this example, the UE-ID is added as part of an RRC Resume Request message
(e.g. using a 'UE-ID' or 'Resume ID' information element and/or the like) although
other messages or information elements may also be used.
[0061] Since the SRBO is configured without PDCP, with Transparent Mode (TM) at RLC,
[0062]
[0063]
and it uses the CCCH logical channel, there are no PDCP/RLC headers for packets
sent via the SRBO (i.e. functions such as security/header compression, reordering,
ARQ, segmentation, etc. associated with PDCP/RLC are not available for such
packets).
Moreover, the size of CCCH and CCCH1 are fixed as 48bits and 64bits, respectively.
In order to allow small data transmissions of other sizes (e.g. larger than 64bits ), a new
CCCH message is defined which can accommodate the small data to be transmitted
and any necessary RRC message and/or information elements (IEs). It will be appreciated
that this new CCCH message may have a variable size (although the size
may be capped, e.g. at a multiple of 48bits or 64bits).
An exemplary CCCH is shown below, which is referred to as 'UL-CCCH2-Message'
(although any other name may be used):
- UL-CCCH2-Message
The UL-CCCH2-Message class is the set of RRC messages that may be sent from the
UE 3 to the network (e.g. base station 5) on the uplink CCCH2 logical channel.
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[Table 1]
UL -CCCH2-Message
-- ASN1 START
-- TAG-UL-CCCH2-MESSAGE-START
UL-CCCH2-Message ::=
message
UL-CCCH2-MessageType ::=
c1
},
smaiiDataTransmission
spare3 NULL,
spare2 NULL,
spare1 NULL
SEQUENCE{
UL -CCCH2-Message Type
CHOICE {
CHOICE {
SmaiiDataTransmission,
messageCiassExtension SEQUENCE {}
-- TAG-UL-CCCH1-MESSAGE-STOP
-- ASN1STOP
[0064] As can be seen, in this example, the contents of the small data transmission (i.e. data
[0065]
[0066]
from higher layers and any associated RRC IE) are included within an appropriate
element of the UL-CCCH2-Message (in this case the 'UL-CCCH2-MessageType'
element). Effectively, the 'smallDataTransmission' part of this message is an RRC
message which includes the (small) data from higher layers and appropriate information
identifying the UE 3 ('UE-ID'). Whilst in this example a new RRC message
('SmallDataTransmission') is used, it will be appreciated that an existing RRC
message may be adapted for the purpose of small data transmission, if appropriate.
The information elements of the RRC message may include for example the IEs
currently defined for the RRCResumeRequest message. In one example, the RRC
message includes the data from the UE 3, an associated UE-ID (for identifying the UE
3 and facilitating UE context retrieval), and one or more security related IE (e.g. a
resume MAC-I and/or the like). Based on this message, the network (in this example
the base station 5) can decide whether to resume the RRC connection for the UE 3.
Further details of this exemplary RRC message are given below:
- SmallDataTransmission
The SmallDataTransmission message is used for the uplink transfer of small data
when the UE 3 is in RRC INACTIVE mode.
Signalling radio bearer: SRBO
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RLC-SAP: TM
Logical channel: CCCH2
Direction: UE to Network
[Table 2]
-- ASN1 START
Small Data Transmission message
-- TAG-RRCRESUMEREQUEST-START
SmaiiDataTransmission ::=
rrcResume Request
Small Data
RRCResumeRequest-IEs ::=
resume Identity
resumeMAC-1
resumeCause
spare
SEQUENCE{
RRCResumeRequest-les
OCTET STRING (SIZE (x))
SEQUENCE{
(Short) 1-RNTI-Value
BIT STRING (SIZE (16)),
ResumeCause,
BIT STRING (SIZE (1 ))
-- TAG-RRCRESUMEREQUEST-STOP
-- ASN1 STOP
[0067] Figure 6 is a schematic flowchart illustrating the main steps for small data
transmission in accordance with the first exemplary method.
[0068] In step 1, the UE 3 receives an explicit indication/configuration from the network to
[0069]
allow small data transmission via the Control-Plane. The indication/configuration may
be sent via an appropriate broadcast message or a unicast message (e.g. an RRC release
message or an RRC suspension message and/or the like). Upon receipt of this message,
the UE 3 configures any applicable restrictions for the small data transmission service
(e.g. transport block size limitation, allowed QoS flows, etc.). If no specific restrictions
are configured, small data transmissions may be allowed up to the maximum size of
CCCH messages (or Msg3/MsgA), for example the PUSCH transport block (TB) size.
Step 2: when small data arrives from an upper layer, and if the size of the data
(optionally with necessary padding and information elements) does not exceed the
maximum size defined for small data transmission (and also pass any other restrictions
specified or configured), the UE 3 initiates the small data transmission procedure.
Specifically, the UE 3 generates the small data transmission message at the RRC layer
(using its RRC module) and sends it to lower layers for transmission (i.e. MAC and
PHY layers). Although not shown in Figure 6, if the data from upper layers cannot be
sent as 'small data' (e.g. due to its size or due to any other applicable restriction), then
16
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[0070]
the UE 3 generates an appropriately formatted RRC resume request message and sends
it to lower layers for transmission so that the data can be transmitted in the normal
manner (in RRC CONNECTED mode).
Step 3: in the MAC layer, the CCCH message transmission triggers an appropriate
random access procedure, i.e. either a 2-step or 4-step random access procedure. The
above described CCCH message is transferred to the network (base station 5) using
either a MsgA or a Msg3. It will be appreciated that, instead of using the random
access procedure, the CCCH message may also be transmitted via a pre-configured
PUSCH resource if it is available.
[0071] Step 4: when a response to the message at step 3 is received (e.g. when an MsgB/
Msg4 is detected), the MAC layer informs the RRC layer about the success of CCCH
message transfer. It will be appreciated that the network may also send an RRC resume
message with the MsgB/Msg4 if the network would like to resume the RRC
connection in response to the small data transfer.
[0072] Beneficially, this method represents a relatively small change in terms of procedures
currently specified by 3GPP. The RRC INACTIVE mode still allows suspending all
configurations (except SRBO). The method does not require any change of behaviour
in the MAC layer (although the grant size configured for MsgA and/or further
preamble partitioning for small data transmission purpose may increase).
[0073] Figure 7 is a schematic overview of the layers involved in small data transmission in
accordance with a second exemplary method. As can be seen, in this example, UserPlane
signalling is used.
[0074] In order to facilitate small data transmissions, the MAC layer (MAC module) is
aware that the UE 3 is in RRC INACTIVE mode and it is also aware of the associated
UE-ID. The MAC layer is configured to add the UE-ID (e.g. using a 'UE-ID' MAC
Control Element (CE)) to the MAC Protocol Data Unit (PDU) and transmit the UE-ID
together with the data. It will be appreciated that any other suitable information
identifying the UE 3 may be used. However, it will be appreciated that the MAC layer
does not need to be aware of the UE-ID. Instead, the UE-ID (or any other information
suitable for identifying the UE 3) may be included in an RRC message (e.g. in an
RRCresumeRequest or similar) and the MAC layer may be configured to multiplex the
RRC message with the processed small data and send them out together to the
network. In this case, the UE-ID may be included in an information element of the
RRC message instead of a MAC CE.
[0075] Figure 8 is a schematic flowchart illustrating the main steps for small data
transmission in accordance with the second exemplary method.
[0076] Step 1: an RRC release (or RRC suspension) message may be sent by the network
(the base station 5) to the UE to set up a new DRB (or to keep an existing DRB alive)
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for small data transmission. Additionally, the network may configure further restrictions
for the small data transmission service, for example, which Quality of
Service (QoS) Flow Identifier(s) (QFI(s)) can be mapped to this DRB and/or any associated
data size/frequency limitation, if applicable. It will be appreciated that a predetermined
(e.g. default) configuration may be used for the DRB which would enable
the UE 3 to continue using it after any subsequent cell (re-)selection. In other words,
the configuration of the DRB may be common for a plurality of base stations, e.g. base
stations within a specific tracking area.
[0077] Step 2: the RRC layer suspends all other DRBs and SRBs, and keeps (or sets up) the
[0078]
[0079]
User-Plane protocol for the DRB that is configured to remain active whilst the UE 3 is
in the RRC INACTIVE mode. At the end of this step, the UE 3 enters the RRC
INACTIVE mode.
Step 3: Whilst in the RRC INACTIVE mode, the UE 3 monitors the higher layers for
data. Upon data arrival, if the data conforms to the 'small data' configuration and it
belongs to a QFI mapped to the active DRB, the UE 3 processed the data through the
appropriate User-Plane protocol of the relevant DRB. It will be appreciated that when
the data from the higher layers does not belong to any QFI mapped to the active DRB
or the data is larger than the maximum size allowed by the current small data
transmission configuration, the UE 3 triggers an appropriate RRC resume procedure
(or a random access procedure) so that the data can be transmitted in the normal
manner (in RRC CONNECTED mode).
Step 4: at the MAC layer, the data may be transmitted either via a pre-configured
PUSCH resource (if available) or by triggering an appropriate (2-step/4-step) random
access procedure for uplink transmission. The MAC layer is also configured to add appropriate
information identifying the UE 3 (e.g. 'UE ID') to the initial uplink
transmission. The information identifying the UE 3 may be included in a MAC CE or
in an RRC information element. It will also be appreciated that several uplink transmissions
(without resuming the RRC connection) may be used in order to transmit data
exceeding the size limit for small data transmission, in which case segmentation may
be necessary at the RLC layer.
[0080] Beneficially, this method allows the UE 3 to cipher/compress the data. Although in
[0081]
this case the RRC INACTIVE mode is similar to the RRC CONNECTED mode, it
results in a lighter User-Plane and lower overhead compared to RRC CONNECTED
mode.
Modifications and Alternatives
Detailed example embodiments have been described above. As those skilled in the
art will appreciate, a number of modifications and alternatives can be made to the
above example embodiments whilst still benefiting from the inventions embodied
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[0082]
[0083]
[0084]
therein. By way of illustration only a number of these alternatives and modifications
will now be described.
Figures 9 and 10 illustrate some possible modifications of the first exemplary method
described above with reference to Figures 5 and 6. Specifically, AS security protection
may be provided using the PDCP layer (as shown in Figure 9) or a higher layer (e.g. a
dedicated security layer, as shown in Figure 10). In this case, security operation may
be applied to the data part by the PDCP layer or the higher layer.
Although the bearer used for small data transmissions over the Control-Plane is
referred to as 'SRBO', it will be appreciated that the SRB used for small data
transmission may have a different name in order to distinguish it from the legacy
'SRBO'.
In case of the second method, the following table provides an overview of some
potential User-Plane configuration restrictions/changes for shorter headers and lower
overall signalling overhead for small data transmissions.
[0085] [Table 3]
Existing Restrictions/changes
SOAP layer: with or without SOAP SOAP layer: restrict to configure
header depending on without SOAP header.
configuration.
POCP layer: supports 12bit/18bit POCP layer: it may be beneficial
POCP sequence number (SN) to introduce a shorter SN (e.g.
which ends up with a POCP ?bits), and target a 1 byte header
header of minimum 2-3 bytes. size.
RLC layer: TM mode is currently RLC layer: since it is one-shot
not applicable to ORB. small data transmission, it may be
beneficial to allow TM mode for
ORB subjected to small data
transmission (i.e. no header, no
ARQ, and no segmentation).
MAC layer: MAC sub-header is 2 MAC layer: it may be beneficial to
or 3 bytes for data and contains avoid LCIO and/or L field, may
Logical Channel Identifier (LCIO) I define one or multiple fix size
Length (L) fields and so on. MAC POU to accommodate data.
UE-10 can be added in for
identifying the UE.
[0086] In the above description, the UE, the (R)AN node, and the core network node are
described for ease of understanding as having a number of discrete modules (such as
the communication control modules). Whilst these modules may be provided in this
way for certain applications, for example where an existing system has been modified
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to implement the invention, in other applications, for example in systems designed
with the inventive features in mind from the outset, these modules may be built into the
overall operating system or code and so these modules may not be discernible as
discrete entities. These modules may also be implemented in software, hardware,
firmware or a mix of these.
[0087] Each controller may comprise any suitable form of processing circuitry including
(but not limited to), for example: one or more hardware implemented computer
processors; microprocessors; central processing units (CPUs); arithmetic logic units
(ALUs); input/output (IO) circuits; internal memories I caches (program and/or data);
processing registers; communication buses (e.g. control, data and/or address buses);
direct memory access (DMA) functions; hardware or software implemented counters,
pointers and/or timers; and/or the like.
[0088] In the above example embodiments, a number of software modules were described.
As those skilled in the art will appreciate, the software modules may be provided in
compiled or un-compiled form and may be supplied to the UE, the (R)AN node, and
the core network node as a signal over a computer network, or on a recording medium.
Further, the functionality performed by part or all of this software may be performed
using one or more dedicated hardware circuits. However, the use of software modules
is preferred as it facilitates the updating of the UE, the (R)AN node, and the core
network node in order to update their functionalities.
[0089] In the current 5G architecture, the gNB internal structure may be split into two parts
[0090]
known as the Central Unit (CU) and the Distributed Unit (DU), connected by an Fl
interface. It will be appreciated that a CU may be connected to (and control) a plurality
of DUs. This enables the use of a 'split' architecture, whereby the, typically 'higher',
CU layers (for example, but not necessarily or exclusively), PDCP) and the, typically
'lower', DU layers (for example, but not necessarily or exclusively, RLC/MAC/PHY)
to be implemented separately. Thus, for example, the higher layer CU functionality for
a number of gNBs may be implemented centrally (for example, by a single processing
unit, or in a cloud-based or virtualised system), whilst retaining the lower layer DU
functionality locally, in each gNB. It will be appreciated that a CU may perform communication
with the next generation core and the DU may perform communication
over an air interface with UEs in the vicinity (i.e. in a cell operated by the gNB).
In more detail, a distributed gNB includes the following functional units:
gNB Central Unit (gNB-CU): a logical node hosting Radio Resource Control (RRC),
Service Data Adaptation Protocol (SDAP) and Packet Data Convergence Protocol
(PDCP) layers of the gNB or RRC and PDCP layers of the En-gNB that controls the
operation of one or more gNB-DUs. The gNB-CU terminates the Fl interface
connected with the gNB-DU.
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gNB Distributed Unit (gNB-DU): a logical node hosting Radio Link Control (RLC),
Medium Access Control (MAC) and Physical (PHY) layers of the gNB or En-gNB,
and its operation is partly controlled by gNB-CU. One gNB-DU supports one or
multiple cells. One cell is supported by only one gNB-DU. The gNB-DU terminates
the Fl interface connected with the gNB-CU.
gNB-CU-Control Plane (gNB-CU-CP): a logical node hosting the RRC and the control
plane part of the PDCP protocol of the gNB-CU for an En-gNB or a gNB. The gNBCU-
CP terminates the El interface connected with the gNB-CU-UP and the Fl-C
interface connected with the gNB-DU.
gNB-CU-User Plane (gNB-CU-UP): a logical node hosting the user plane part of the
PDCP protocol of the gNB-CU for an En-gNB, and the user plane part of the PDCP
protocol and the SDAP protocol of the gNB-CU for a gNB. The gNB-CU-UP
terminates the El interface connected with the gNB-CU-CP and the Fl-U interface
connected with the gNB-DU.
[0091] The User Equipment (or "UE") in the present disclosure is an entity connected to a
network via a wireless interface. The UE may also be referred to as "mobile station",
"mobile device", "wireless device", or "wireless transmit/receive unit" (WTRU).
[0092] It should be noted that the present disclosure is not limited to a dedicated commu-
[0093]
nication device, and can be applied to any device having a communication function as
explained in the following paragraphs.
The terms "User Equipment" or "UE" (as the term is used by 3GPP), "mobile
station", "mobile device", and "wireless device" are generally intended to be
synonymous with one another, and include standalone mobile stations, such as
terminals, cell phones, smart phones, tablets, cellular loT devices, loT devices, and
machinery. It will be appreciated that the terms "mobile station" and "mobile device"
also encompass devices that remain stationary for a long period of time.
[0094] A UE may, for example, be an item of equipment for production or manufacture and/
or an item of energy related machinery (for example equipment or machinery such as:
boilers; engines; turbines; solar panels; wind turbines; hydroelectric generators;
thermal power generators; nuclear electricity generators; batteries; nuclear systems
and/or associated equipment; heavy electrical machinery; pumps including vacuum
pumps; compressors; fans; blowers; oil hydraulic equipment; pneumatic equipment;
metal working machinery; manipulators; robots and/or their application systems; tools;
molds or dies; rolls; conveying equipment; elevating equipment; materials handling
equipment; textile machinery; sewing machines; printing and/or related machinery;
paper converting machinery; chemical machinery; mining and/or construction
machinery and/or related equipment; machinery and/or implements for agriculture,
forestry and/or fisheries; safety and/or environment preservation equipment; tractors;
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precision bearings; chains; gears; power transmission equipment; lubricating
equipment; valves; pipe fittings; and/or application systems for any of the previously
mentioned equipment or machinery etc.).
[0095] A UE may, for example, be an item of transport equipment (for example transport
[0096]
[0097]
[0098]
[0099]
[0100]
[0101]
equipment such as: rolling stocks; motor vehicles; motor cycles; bicycles; trains;
buses; carts; rickshaws; ships and other watercraft; aircraft; rockets; satellites; drones;
balloons etc.).
A UE may, for example, be an item of information and communication equipment
(for example information and communication equipment such as: electronic computer
and related equipment; communication and related equipment; electronic components
etc.).
A UE may, for example, be a refrigerating machine, a refrigerating machine applied
product, an item of trade and/or service industry equipment, a vending machine, an
automatic service machine, an office machine or equipment, a consumer electronic and
electronic appliance (for example a consumer electronic appliance such as: audio
equipment; video equipment; a loud speaker; a radio; a television; a microwave oven; a
rice cooker; a coffee machine; a dishwasher; a washing machine; a dryer; an electronic
fan or related appliance; a cleaner etc.).
A UE may, for example, be an electrical application system or equipment (for
example an electrical application system or equipment such as: an x-ray system; a
particle accelerator; radio isotope equipment; sonic equipment; electromagnetic application
equipment; electronic power application equipment etc.).
A UE may, for example, be an electronic lamp, a luminaire, a measuring instrument,
an analyzer, a tester, or a surveying or sensing instrument (for example a surveying or
sensing instrument such as: a smoke alarm; a human alarm sensor; a motion sensor; a
wireless tag etc.), a watch or clock, a laboratory instrument, optical apparatus, medical
equipment and/or system, a weapon, an item of cutlery, a hand tool, or the like.
A UE may, for example, be a wireless-equipped personal digital assistant or related
equipment (such as a wireless card or module designed for attachment to or for
insertion into another electronic device (for example a personal computer, electrical
measuring machine)).
A UE may be a device or a part of a system that provides applications, services, and
solutions described below, as to 'internet of things' (loT), using a variety of wired and/
or wireless communication technologies.
[0 102] Internet of Things devices (or "things") may be equipped with appropriate
electronics, software, sensors, network connectivity, and/or the like, which enable
these devices to collect and exchange data with each other and with other communication
devices. loT devices may comprise automated equipment that follow software
22
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[0103]
instructions stored in an internal memory. loT devices may operate without requiring
human supervision or interaction. loT devices might also remain stationary and/or
inactive for a long period of time. loT devices may be implemented as a part of a
(generally) stationary apparatus. loT devices may also be embedded in non-stationary
apparatus (e.g. vehicles) or attached to animals or persons to be monitored/tracked.
It will be appreciated that loT technology can be implemented on any communication
devices that can connect to a communications network for sending/receiving
data, regardless of whether such communication devices are controlled by human input
or software instructions stored in memory.
[0104] It will be appreciated that loT devices are sometimes also referred to as Machine-
[0105]
Type Communication (MTC) devices or Machine-to-Machine (M2M) communication
devices. It will be appreciated that a UE may support one or more loT or MTC applications.
Some examples of MTC applications are listed in the following table
(source: 3GPP TS 22.368 V13.1.0, Annex B, the contents of which are incorporated
herein by reference). This list is not exhaustive and is intended to be indicative of some
examples of machine type communication applications.
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[Table 4]
Service Area MTC applications
Surveillance systems
Backup for landline
Security Control of physical access (e.g. to
buildings)
Car/driver security
Fleet Management
Order Management
Pay as you drive
Tracking & Tracing Asset Tracking
Navigation
Traffic information
Road tolling
Road traffic optimisation/steering
Point of sales
Payment Vending machines
Gaming machines
Monitoring vital signs
Health
Supporting the aged or handicapped
Web Access Telemedicine points
Remote diagnostics
Sensors
Lighting
Remote Pumps
Maintenance/Control
Valves
Elevator control
Vending machine control
Vehicle diagnostics
Power
Gas
Metering
Water
Heating
Grid control
Industrial metering
Digital photo frame
Consumer Devices Digital camera
eBook
Applications, services, and solutions may be an Mobile Virtual Network Operator
(MVNO) service, an emergency radio communication system, a Private Branch
eXchange (PBX) system, a PHS/Digital Cordless Telecommunications system, a Point
of sale (POS) system, an advertise calling system, a Multimedia Broadcast and
Multicast Service (MBMS), a Vehicle to Everything (V2X) system, a train radio
system, a location related service, a Disaster/Emergency Wireless Communication
Service, a community service, a video streaming service, a femto cell application
service, a Voice over L TE (VoLTE) service, a charging service, a radio on demand
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[0106]
[0107]
[0108]
service, a roaming service, an activity monitoring service, a telecom carrier/
communication NW selection service, a functional restriction service, a Proof of
Concept (PoC) service, a personal information management service, an ad-hoc
network/Delay Tolerant Networking (DTN) service, etc.
Further, the above-described UE categories are merely examples of applications of
the technical ideas and exemplary embodiments described in the present document.
Needless to say, these technical ideas and example embodiments are not limited to the
above-described UE and various modifications can be made thereto.
The RRC message may comprise the small data transmission and one or more RRC
information elements. The RRC message may comprise information identifying said
UE (e.g. a 'UE-ID' information element). The SRB may be 'SRBO'.
The RRC message comprising the small data transmission may be transmitted using
a resource associated with a 'configured grant type-1'. Altemati vel y, the RRC message
comprising said small data transmission may be transmitted via a message forming part
of a random access procedure (e.g. 'Msg3' or 'MsgA').
[0109] Access Stratum security may be provided for small data transmission via a layer
other than an RRC layer (e.g. a Packet Data Convergence Protocol (PDCP) layer and/
or a dedicated security layer).
[0110] The determining by the UE may comprise determining whether a Quality of Service
(QoS) Flow Identifier (QFI) associated with the small data transmission can be mapped
to the SRB, and the method may comprise transmitting the RRC message comprising
small data transmission based on a result of the determination.
[0111] The information configuring small data transmissions may comprise information
identifying a size limit for said CCCH and the determining by the UE may comprise
determining that said small data transmission does not exceed said size limit.
[0112] The information identifying the UE may comprise a Medium Access Control (MAC)
layer Control Element (CE) (e.g. a 'UE-ID' MAC CE) or an RRC information element.
[0113] The processing by the UE may comprise segmenting said uplink data to form a
plurality of small data transmissions and adding the information identifying the UE to
at least one of the plurality of small data transmissions.
[0114] The determining by the UE may comprise determining whether a Quality of Service
(QoS) Flow Identifier (QFI) associated with the small data transmission can be mapped
to the DRB, and the method may comprise transmitting the small data transmission and
the information identifying the UE based on a result of the determination.
[0115] The processing of uplink data to form a small data transmission may comprise configuring
at least one layer of the DRB for small data transmission. For example, the
configuring may comprise at least one of: configuring a Service Data Adaptation
Protocol (SDAP) layer without an SDAP header; using a shortened Packet Data Con25
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[0116]
[0117]
vergence Protocol (PDCP) sequence number (e.g. 7bits) and/or using a 1 byte PDCP
header size; using a Transparent Mode (TM) for small data transmission using said
DRB; configuring a Medium Access Control (MAC) layer without a Logical Channel
Identifier (LCID) and/or a Length field; and configuring a fixed size MAC Protocol
Data Unit (PDU) for small data transmission.
Various other modifications will be apparent to those skilled in the art and will not be
described in further detail here.
(Supplementary Note 1)
A method performed by a user equipment (UE) for small data transmission in Radio
Resource Control (RRC) Inactive state, the method comprising:
receiving information configuring small data transmissions via a control-plane;
determining, whilst the UE is in the RRC Inactive state, whether there is uplink data
to be sent as a small data transmission;
generating an RRC message comprising said small data transmission; and
transmitting said RRC message comprising said small data transmission using a
Signalling Radio Bearer (SRB) provided via a Common Control Channel (CCCH).
[0118] (Supplementary Note 2)
[0119]
The method according to supplementary note 1, wherein the RRC message comprises
said small data transmission and one or more RRC information elements.
(Supplementary Note 3)
The method according to supplementary note 1 or 2, wherein the RRC message
comprises information identifying said UE (e.g. a 'UE-ID' information element).
[0120] (Supplementary Note 4)
[0121]
The method according to any of supplementary notes 1 to 3, wherein the SRB is an
'SRBO'.
(Supplementary Note 5)
The method according to any of supplementary notes 1 to 4, wherein said RRC
message comprising said small data transmission is transmitted using a resource associated
with a 'configured grant type-1'.
[0122] (Supplementary Note 6)
The method according to any of supplementary notes 1 to 4, wherein said RRC
message comprising said small data transmission is transmitted via a message forming
part of a random access procedure (e.g. 'Msg3' or 'MsgA').
[0123] (Supplementary Note 7)
The method according to any of supplementary notes 1 to 6, wherein Access Stratum
security is provided for said small data transmission via other than an RRC layer (e.g. a
Packet Data Convergence Protocol (PDCP) layer and/or a dedicated security layer).
[0124] (Supplementary Note 8)
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[0125]
[0126]
The method according to any of supplementary notes 1 to 7, wherein said determining
comprises determining whether a Quality of Service (QoS) Flow Identifier (QFI) associated
with the small data transmission can be mapped to the SRB, and wherein the
method comprises transmitting said RRC message comprising said small data
transmission based on a result of said determination.
(Supplementary Note 9)
The method according to any of supplementary notes 1 to 8, wherein said Information
configuring small data transmissions comprises information identifying a
size limit for said CCCH and wherein said determining comprises determining that
said small data transmission does not exceed said size limit.
(Supplementary Note 10)
A method performed by a user equipment (UE) for small data transmission in Radio
Resource Control (RRC) Inactive state, the method comprising:
receiving information configuring small data transmissions in the RRC Inactive state;
determining, when the UE is in the RRC Inactive state, whether there is uplink data
to be sent as a small data transmission;
processing the uplink data to form a small data transmission and adding information
identifying the UE; and
transmitting said small data transmission and said information identifying the UE
using a Data Radio Bearer (DRB) based on the received information.
[0127] (Supplementary Note 11)
[0128]
[0129]
[0130]
The method according to supplementary note 10, wherein said small data
transmission is transmitted using a resource associated with a 'configured grant type-
1'.
(Supplementary Note 12)
The method according to supplementary note 10, wherein said small data
transmission is transmitted via a message forming part of a random access procedure
(e.g. 'Msg3' or 'MsgA').
(Supplementary Note 13)
The method according to any of supplementary notes 10 to 12, wherein said Information
identifying the UE comprises a Medium Access Control (MAC) Control
Element (CE) (e.g. a 'UE-ID' MAC CE) or an RRC information element.
(Supplementary Note 14)
The method according to any of supplementary notes 10 to 13, wherein said
processing comprises segmenting said uplink data to form a plurality of small data
transmissions and adding said information identifying the UE to at least one of said
plurality of small data transmissions.
[0131] (Supplementary Note 15)
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The method according to any of supplementary notes 10 to 14, wherein said determining
comprises determining whether a Quality of Service (QoS) Flow Identifier
(QFI) associated with the small data transmission can be mapped to the DRB, and
wherein the method comprises transmitting said small data transmission and said Information
identifying the UE based on a result of said determination.
[0132] (Supplementary Note 16)
The method according to any of supplementary notes 10 to 15, wherein said
processing the uplink data to form a small data transmission comprises configuring at
least one layer of said DRB for small data transmission.
[0133] (Supplementary Note 17)
[0134]
The method according to supplementary note 16, wherein said configuring the at
least one layer of said DRB for small data transmission comprises at least one of:
- configuring a Service Data Adaptation Protocol (SDAP) layer without an SDAP
header;
- using a shortened Packet Data Convergence Protocol (PDCP) sequence number
(e.g. 7bits) and/or using a 1 byte PDCP header size;
-using a Transparent Mode (TM) for small data transmission using said DRB;
- configuring a Medium Access Control (MAC) layer without a Logical Channel
Identifier (LCID) and/or a Length field; and
- configuring a fixed size MAC Protocol Data Unit (PDU) for small data
transmis sian.
(Supplementary Note 18)
A method performed by a communication apparatus of a radio access network for
communicating with a user equipment (UE) for small data transmission in a Radio
Resource Control (RRC) Inactive state, the method comprising:
transmitting information configuring small data transmissions via a control-plane;
and
receiving, from the UE whilst the UE is in the RRC Inactive state, an RRC message
comprising a small data transmission using a Signalling Radio Bearer (SRB) provided
via a Common Control Channel (CCCH).
[0135] (Supplementary Note 19)
A method performed by a communication apparatus of a radio access network for
communicating with a user equipment (UE) for small data transmission in Radio
Resource Control (RRC) Inactive state, the method comprising:
transmitting information configuring small data transmissions in the RRC Inactive
state; and
receiving, from the UE whilst the UE is in the RRC Inactive state, a small data
transmission and information identifying the UE using a Data Radio Bearer (DRB)
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[0136]
[0137]
based on the transmitted information.
(Supplementary Note 20)
A user equipment (UE) for small data transmission in Radio Resource Control (RRC)
Inactive state, the UE comprising:
means for receiving information configuring small data transmissions via a controlplane;
means for determining, whilst the UE is in the RRC Inactive state, whether there is
uplink data to be sent as a small data transmission;
means for generating an RRC message comprising said small data transmission; and
means for transmitting said RRC message comprising said small data transmission
using a Signalling Radio Bearer (SRB) provided via a Common Control Channel
(CCCH).
(Supplementary Note 21)
A user equipment (UE) for small data transmission in Radio Resource Control (RRC)
Inactive state, the UE comprising:
means for receiving information configuring small data transmissions in the RRC
Inactive state;
means for determining, when the UE is in the RRC Inactive state, whether there is
uplink data to be sent as a small data transmission;
means for processing the uplink data to form a small data transmission and adding Information
identifying the UE; and
means for transmitting said small data transmission and said information identifying
the UE using a Data Radio Bearer (DRB) based on the received information.
[0138] (Supplementary Note 22)
Communication apparatus of a radio access network for communicating with a user
equipment (UE) for small data transmission in a Radio Resource Control (RRC)
Inactive state, the communication apparatus comprising:
means for transmitting information configuring small data transmissions via a
control-plane; and
means for receiving, from the UE whilst the UE is in the RRC Inactive state, an RRC
message comprising a small data transmission using a Signalling Radio Bearer (SRB)
provided via a Common Control Channel (CCCH).
[0139] (Supplementary Note 23)
Communication apparatus of a radio access network for communicating with a user
equipment (UE) for small data transmission in Radio Resource Control (RRC) Inactive
state, the communication apparatus comprising:
means for transmitting information configuring small data transmissions in the RRC
Inactive state; and
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means for receiving, from the UE whilst the UE is in the RRC Inactive state, a small
data transmission and information identifying the UE using a Data Radio Bearer
(DRB) based on the transmitted information.
[0140] This application is based upon and claims the benefit of priority from United
Kingdom Patent Application No.2004520.9, filed on March 27, 2020, the disclosure of
which is incorporated herein in its entirety by reference.

[Claim 1]
[Claim 2]
[Claim 3]
[Claim 4]
[Claim 5]
[Claim 6]
[Claim 7]
[Claim 8]
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PCT/JP2021/008348
Claims
A method performed by a user equipment (UE) for small data
transmission in Radio Resource Control (RRC) Inactive state, the
method comprising:
receiving information configuring small data transmissions via a
control-plane;
determining, whilst the UE is in the RRC Inactive state, whether there
is uplink data to be sent as a small data transmission;
generating an RRC message comprising said small data transmission;
and
transmitting said RRC message comprising said small data
transmission using a Signalling Radio Bearer (SRB) provided via a
Common Control Channel (CCCH).
The method according to claim 1, wherein the RRC message comprises
said small data transmission and one or more RRC information
elements.
The method according to claim 1 or 2, wherein the RRC message
comprises information identifying said UE (e.g. a 'UE-ID' information
element).
The method according to any of claims 1 to 3, wherein the SRB is an
'SRBO'.
The method according to any of claims 1 to 4, wherein said RRC
message comprising said small data transmission is transmitted using a
resource associated with a 'configured grant type-1 '.
The method according to any of claims 1 to 4, wherein said RRC
message comprising said small data transmission is transmitted via a
message forming part of a random access procedure (e.g. 'Msg3' or
'MsgA').
The method according to any of claims 1 to 6, wherein Access Stratum
security is provided for said small data transmission via other than an
RRC layer (e.g. a Packet Data Convergence Protocol (PDCP) layer
and/or a dedicated security layer).
The method according to any of claims 1 to 7, wherein said determining
comprises determining whether a Quality of Service (QoS)
Flow Identifier (QFI) associated with the small data transmission can
be mapped to the SRB, and wherein the method comprises transmitting
said RRC message comprising said small data transmission based on a
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[Claim 9]
[Claim 10]
[Claim 11]
[Claim 12]
[Claim 13]
[Claim 14]
[Claim 15]
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PCT/JP2021/008348
result of said determination.
The method according to any of claims 1 to 8, wherein said information
configuring small data transmissions comprises information identifying
a size limit for said CCCH and wherein said determining comprises determining
that said small data transmission does not exceed said size
limit.
A method performed by a user equipment (UE) for small data
transmission in Radio Resource Control (RRC) Inactive state, the
method comprising:
receiving information configuring small data transmissions in the RRC
Inactive state;
determining, when the UE is in the RRC Inactive state, whether there is
uplink data to be sent as a small data transmission;
processing the uplink data to form a small data transmission and adding
information identifying the UE; and
transmitting said small data transmission and said information
identifying the UE using a Data Radio Bearer (DRB) based on the
received information.
The method according to claim 10, wherein said small data
transmission is transmitted using a resource associated with a
'configured grant type-1 '.
The method according to claim 10, wherein said small data
transmission is transmitted via a message forming part of a random
access procedure (e.g. 'Msg3' or 'MsgA').
The method according to any of claims 10 to 12, wherein said Information
identifying the UE comprises a Medium Access Control
(MAC) Control Element (CE) (e.g. a 'UE-ID' MAC CE) or an RRC mformation
element.
The method according to any of claims 10 to 13, wherein said
processing comprises segmenting said uplink data to form a plurality of
small data transmissions and adding said information identifying the
UE to at least one of said plurality of small data transmissions.
The method according to any of claims 10 to 14, wherein said determining
comprises determining whether a Quality of Service (QoS)
Flow Identifier (QFI) associated with the small data transmission can
be mapped to the DRB, and wherein the method comprises transmitting
said small data transmission and said information identifying the UE
based on a result of said determination.
wo 2021/192882
[Claim 16]
[Claim 17]
[Claim 18]
[Claim 19]
[Claim 20]
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PCT/JP2021/008348
The method according to any of claims 10 to 15, wherein said
processing the uplink data to form a small data transmission comprises
configuring at least one layer of said DRB for small data transmission.
The method according to claim 16, wherein said configuring the at least
one layer of said DRB for small data transmission comprises at least
one of:
- configuring a Service Data Adaptation Protocol (SDAP) layer without
an SDAP header;
- using a shortened Packet Data Convergence Protocol (PDCP)
sequence number (e.g. 7bits) and/or using a 1 byte PDCP header size;
- using a Transparent Mode (TM) for small data transmission using said
DRB;
- configuring a Medium Access Control (MAC) layer without a Logical
Channel Identifier (LCID) and/or a Length field; and
-configuring a fixed size MAC Protocol Data Unit (PDU) for small
data transmission.
A method performed by a communication apparatus of a radio access
network for communicating with a user equipment (UE) for small data
transmission in a Radio Resource Control (RRC) Inactive state, the
method comprising:
transmitting information configuring small data transmissions via a
control-plane; and
receiving, from the UE whilst the UE is in the RRC Inactive state, an
RRC message comprising a small data transmission using a Signalling
Radio Bearer (SRB) provided via a Common Control Channel
(CCCH).
A method performed by a communication apparatus of a radio access
network for communicating with a user equipment (UE) for small data
transmission in Radio Resource Control (RRC) Inactive state, the
method comprising:
transmitting information configuring small data transmissions in the
RRC Inactive state; and
receiving, from the UE whilst the UE is in the RRC Inactive state, a
small data transmission and information identifying the UE using a
Data Radio Bearer (DRB) based on the transmitted information.
A user equipment (UE) for small data transmission in Radio Resource
Control (RRC) Inactive state, the UE comprising:
means for receiving information configuring small data transmissions
wo 2021/192882
[Claim 21]
[Claim 22]
[Claim 23]
33
PCT/JP2021/008348
via a control-plane;
means for determining, whilst the UE is in the RRC Inactive state,
whether there is uplink data to be sent as a small data transmission;
means for generating an RRC message comprising said small data
transmission; and
means for transmitting said RRC message comprising said small data
transmission using a Signalling Radio Bearer (SRB) provided via a
Common Control Channel (CCCH).
A user equipment (UE) for small data transmission in Radio Resource
Control (RRC) Inactive state, the UE comprising:
means for receiving information configuring small data transmissions
in the RRC Inactive state;
means for determining, when the UE is in the RRC Inactive state,
whether there is uplink data to be sent as a small data transmission;
means for processing the uplink data to form a small data transmission
and adding information identifying the UE; and
means for transmitting said small data transmission and said Information
identifying the UE using a Data Radio Bearer (DRB) based
on the received information.
Communication apparatus of a radio access network for communicating
with a user equipment (UE) for small data transmission in a
Radio Resource Control (RRC) Inactive state, the communication
apparatus comprising:
means for transmitting information configuring small data transmissions
via a control-plane; and
means for receiving, from the UE whilst the UE is in the RRC Inactive
state, an RRC message comprising a small data transmission using a
Signalling Radio Bearer (SRB) provided via a Common Control
Channel (CCCH).
Communication apparatus of a radio access network for communicating
with a user equipment (UE) for small data transmission in
Radio Resource Control (RRC) Inactive state, the communication
apparatus comprising:
means for transmitting information configuring small data transmissions
in the RRC Inactive state; and
means for receiving, from the UE whilst the UE is in the RRC Inactive
state, a small data transmission and information identifying the UE
using a Data Radio Bearer (DRB) based on the transmitted information.