U.S. patent application number 14/226273 was filed with the patent office on 2014-07-24 for offline device paging.
This patent application is currently assigned to TELEFONAKTIEBOLAGET L M ERICSSON (PUBL). The applicant listed for this patent is Zu QIANG. Invention is credited to Zu QIANG.
Application Number | 20140206333 14/226273 |
Document ID | / |
Family ID | 45815924 |
Filed Date | 2014-07-24 |
United States Patent
Application |
20140206333 |
Kind Code |
A1 |
QIANG; Zu |
July 24, 2014 |
OFFLINE DEVICE PAGING
Abstract
The network resources allocated to Machine Type Communication
(MTD) devices (also referred to as Machine-to-Machine (M2M)
Devices) can be reduced through the introduction of a new device
state in a network. The network device state, referred to as a
sleep state, allows the network to offload context information
about the device to another network element so that the resources
allocated to the sleeping device can be released. When the device
needs to be contacted by a network element, the stored context
information can be retrieved to facilitate paging the otherwise
offline device.
Inventors: |
QIANG; Zu; (Kirkland,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
QIANG; Zu |
Kirkland |
|
CA |
|
|
Assignee: |
TELEFONAKTIEBOLAGET L M ERICSSON
(PUBL)
Stockholm
SE
|
Family ID: |
45815924 |
Appl. No.: |
14/226273 |
Filed: |
March 26, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13401398 |
Feb 21, 2012 |
8725160 |
|
|
14226273 |
|
|
|
|
61444923 |
Feb 21, 2011 |
|
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Current U.S.
Class: |
455/418 |
Current CPC
Class: |
H04W 8/06 20130101; Y02D
70/24 20180101; Y02D 70/10 20180101; H04W 8/24 20130101; H04W 60/04
20130101; Y02D 70/00 20180101; Y02D 70/14 20180101; H04W 8/12
20130101; Y02D 70/20 20180101; H04W 76/34 20180201; Y02D 70/21
20180101; Y02D 70/142 20180101; Y02D 30/70 20200801; H04W 4/70
20180201; H04W 52/0235 20130101 |
Class at
Publication: |
455/418 |
International
Class: |
H04W 52/02 20060101
H04W052/02; H04W 8/24 20060101 H04W008/24 |
Claims
1. A method of managing resources allocated to user equipment in a
network, the method comprising: receiving, from a user equipment
over a radio access network, an indication that the user equipment
is entering a low traffic state; transferring context information
associated with the user equipment to a secondary storage; and
de-allocating network resources associated with the user equipment
in response to the receipt of the indication.
2. The method of claim 1 wherein the step of receiving includes
receiving a SLEEP request message.
3. The method of claim 1 wherein the step of receiving further
includes receiving an indication that the user equipment is
unlikely to change network cells.
4. The method of claim 1 wherein the step of transferring includes
transferring the context information to an external secondary
storage.
5. The method of claim 4 wherein the step of transferring includes
transmitting context information stored in a local primary storage
to the secondary storage residing in a Machine Type Communication
Tracking Server.
6. The method of claim 1 wherein the step of de-allocating network
resources includes discarding a portion of the context information
transferred to the secondary storage.
7. The method of claim 1 wherein the step of de-allocating network
resources includes keeping a first part of the context information
transferred to secondary storage, and discarding a second part of
the context information transferred to secondary storage.
8. The method of claim 7 wherein the step of de-allocating network
resources includes transmitting a message to an external node
instructing the external node to release resources allocated to the
user equipment.
9. A node for storing context information about user equipment
connected to a radio access network, the node comprising: a primary
storage for storing context information associated with user
equipment; a radio interface for receiving requests transmitted
over a radio access network from user equipment; a network
interface for communicating with external nodes; and a processor
for receiving, from a user equipment over the radio interface, an
indication that the user equipment is entering a low traffic state,
for transmitting to a secondary storage context information
associated with the user equipment stored in the primary storage,
for deleting at least part of the context information transmitted
to the secondary storage from the primary storage, and for
transmitting a request to at least one external node over the
network interface to release resources allocated to the user
equipment in response to the receipt of the indication.
10. The node of claim 10 wherein the radio interface is a network
interface connecting the node to a radio access network
basestation.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 13/401,398 filed 21 Feb., 2012 and entitled
"Offline Device Paging", which claims the benefit of priority from
U.S. Provisional Patent Application No. 61/444923 filed 21 Feb.,
2011 and entitled "Offline Device Paging", the contents of which
are expressly incorporated herein by reference.
TECHNICAL FIELD
[0002] This disclosure relates generally to enabling a new status
condition for devices connected to a network through a radio access
channel.
BACKGROUND
[0003] In conventional cellular networks, a device connected
through a radio access channel has often been thought of as a
mobile device. As a result, the rules governing the behavior of the
device, and the manner in which the device is handled in the
network have been designed to account for the fact that the device
is mobile and will be prone to moving between cells.
[0004] This perception is starting to change, as there is a growing
demand for Machine-to-Machine (M2M) devices, which engage in what
is often referred to as of machine type device communication
(MTC).
[0005] The machine type device is often viewed as a sensor or a
meter, such as an electrical or water consumption meter, although
other types of connected devices are known. These devices use radio
access channels to connect to the same data network that mobile
devices connect to, but they are often less mobile and more
tolerant of many other conditions. As these devices become more
common, the expected number of deployed MTC devices will increase,
possibly into the millions. As the numbers of deployed devices
expand, the number of active devices in a network cell will also
likely increase. One skilled in the art will appreciate that there
are practical limits to the number of different devices that can
share a cell in a radio access network. Beyond that limit, the
quality of connection is degraded, and network planning must be
re-evaluated. A number of different approaches can be pursued to
mitigate the effects of a large number of MTC devices in a cell.
One solution is to restrict the number of MTC devices will a
connection to the cellular network through the use of other
networking technologies. As an example, devices can be connected to
each other through a WiFi network (IEEE 802.11x) and only one of
the devices will then connect to the radio access network. This
offers a number of benefits, but can introduce problems in allowing
a plurality of different vendors from offering solutions.
[0006] Even with the use of gateways, the number of devices in a
given network cell can increase to the point at which there are too
many MTC devices active at a single time. When this happens, the
degraded radio access network connection will be noticeable, will
adversely affect the experience of human operated devices and will
cause operational difficulties for the network. Often the
communications of an MTC device are not immediately time-sensitive,
and can easily be delayed when data traffic volumes are high,
whereas for a human operated device, this is seen by the user as
being a network outage. As the number of MTC devices increases,
there is an increased likelihood of the MTC devices contributing to
or causing network overloading. This will likely be caused if too
many machine type devices communicate with the network at the same
time. Even if each MTC device only generates a small amount of data
signaling traffic, a sufficiently large volume of devices will lead
to network overloading.
[0007] From the perspective of a network operator it is desirable
to reduce the amount of network signaling caused by these devices.
It may also be advantageous for the MTC device to remain offline if
it is not active. However, the devices often cannot be inactivated
as they must be reachable by network elements. Conventional devices
can enter a sleep mode to conserve power (which is very useful when
the device is powered by batteries) but the device typically
remains sufficiently active to respond to a network page. To the
network, this device is still attached, and consumes resources in
the network. From the network perspective, the device is either
seen as being attached to the network or detached from the network.
When a device is connected, or attached to the network, resources
are consumed in the network to allow the device to be contacted.
When the device is detached, the network no longer has enough
information to contact the device.
[0008] Many mobile network standards are developed by the 3rd
Generation Partnership Project (3GPP). Current 3GPP standards
define devices (also referred to as user equipment (UE)) as being
either REGISTERED or DEREGISTERED. A REGISTERED device can be IDLE
or connected. In the DEREGISTERED state, no UE context information
is saved in the network. The UE location (part of the context
information) of a DEREGISTERED device is not available, and as such
the network does not have sufficient information to allow it to
page the device, as such the UE is determined to be not
reachable.
[0009] In the REGISTERED state, the UE has performed a successful
registration with the network. The network has valid context
information for the UE including valid location or routing
information. This location information need not be exact but
instead can simply identify the last cell or cells that the UE was
known to be in. This allows the network to generate a page that
will reach the UE. The UE is typically required update the network
by performing a Tracking Area Update procedure, either periodically
or when moving into a new tracking area (such as a new cell). This
allows the network to have current location context for the UE, and
allows the UE to be reachable.
[0010] From a REGISTERED state, the UE enters CONNECTED state when
there is traffic between the UE and the network. In a CONNECTED
state, the network does not need to page the UE as there is an
active connection. The UE remains in an IDLE state when no
signaling between UE and network exists. An IDLE mode UE can be
reachable by a paging procedure. As will be appreciated, both IDLE
and CONNECTED devices are viewed as REGISTERED, and both consume
resources in the network, although the resources that they consume
may be different.
[0011] As the number of the machine type devices increases it is
important to provide a mechanism to help to alleviate network
overloading. To facilitate this, it is envisioned that a network
operator may benefit from the ability to force an MTC device to
remain effectively off-line when not communicating. Conventionally
this means that the device would have to be DEREGISTERED, which
would prevent to device from being reachable, and may result in
increased traffic when a plurality of such devices all register at
the same time. One skilled in the art will appreciate that
DEREGISTERING a device to conserve resources is a generally
undesirable result as the device is then no longer reachable.
[0012] There exist many prior art references, such as PCT
Publication No. WO 2011/002819 A1 entitled "Device, method and
Apparatus for Offline Discontinuous Reception (DRX) Processing in
Cellular Systems" that relate to how a mobile device can enter a
power saving state and still receive network signaling, but there
is a dearth of teachings on how the network can reduce the
resources allocated to such a device.
[0013] Therefore, it would be desirable to provide a system and
method that obviate or mitigate the above described problems
SUMMARY
[0014] It is an object of the present invention to obviate or
mitigate at least one disadvantage of the prior art.
[0015] In a first aspect of the present invention, there is
provided a method of managing resources allocated to user equipment
in a network. The method comprises the steps of receiving an
indication, transferring context information, and de-allocating
network resources. In the step of receiving, an indication is
received from a user equipment over a radio access network, that
the user equipment is entering a low traffic state. In the step of
transferring, context information associated with the user
equipment is transferred to a secondary storage. In the step of
de-allocating, network resources associated with the user equipment
are de-allocated in response to the receipt of the indication.
[0016] In an embodiment of the first aspect of the present
invention, the step of receiving includes receiving a SLEEP request
message. In another embodiment, the step of receiving further
includes receiving an indication that the user equipment is
unlikely to change network cells. In a further embodiment, the step
of transferring includes transferring the context information to an
external secondary storage, and optionally includes transmitting
context information stored in a local primary storage to the
secondary storage residing in a Machine Type Communication Tracking
Server. In another embodiment, the step of de-allocating network
resources includes discarding a portion of the context information
transferred to the secondary storage. In a yet a further
embodiment, the step of de-allocating network resources includes
keeping a first part of the context information transferred to
secondary storage, and discarding a second part of the context
information transferred to secondary storage, and optionally
includes transmitting a message to an external node instructing the
external node to release resources allocated to the user
equipment.
[0017] In a second aspect of the present invention, there is
provided a node for storing context information about user
equipment connected to a radio access network. The node comprises a
primary storage, a radio interface, a network interface, and a
processor. The primary storage is for storing context information
associated with user equipment. The radio interface receives
requests from user equipment, either directly through a radio
access network interface or through a network interface connected
to a radio access network base station. The network interface
allows communication with external nodes. The processor receives,
from a user equipment over the radio interface, an indication that
the user equipment is entering a low traffic state, transmits to a
secondary storage context information associated with the user
equipment stored in the primary storage, deletes at least part of
the context information transmitted to the secondary storage from
the primary storage, and transmits a request to at least one
external node over the network interface to release resources
allocated to the user equipment in response to the receipt of the
indication.
[0018] Other aspects and features of the present invention will
become apparent to those ordinarily skilled in the art upon review
of the following description of specific embodiments of the
invention in conjunction with the accompanying figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Embodiments of the present invention will now be described,
by way of example only, with reference to the attached Figures,
wherein:
[0020] FIG. 1 is a block diagram illustrating an exemplary system
architecture for an embodiment of the present invention;
[0021] FIG. 2 is a flow diagram illustrating the transition between
states in a system of the present invention;
[0022] FIG. 3 is a flow chart illustrating a method of the present
invention;
[0023] FIG. 4 is a flow chart illustrating a method of the present
invention;
[0024] FIG. 5 is a flow chart illustrating a method of the present
invention;
[0025] FIG. 6 is a flow chart illustrating a method of the present
invention;
[0026] FIG. 7 is a flow chart illustrating a method of the present
invention; and
[0027] FIG. 8 is a block diagram illustrating a node of the present
invention.
DETAILED DESCRIPTION
[0028] The present invention is directed to a system and method for
reducing the network resource consumption of IDLE, but connected
MTC devices.
[0029] Reference may be made below to specific elements, numbered
in accordance with the attached figures. The discussion below
should be taken to be exemplary in nature, and not as limiting of
the scope of the present invention. The scope of the present
invention is defined in the claims, and should not be considered as
limited by the implementation details described below, which as one
skilled in the art will appreciate, can be modified by replacing
elements with equivalent functional elements.
[0030] To facilitate the reduction in resources allocated to MTC
devices, it must be realized that a mobile device must be
registered so that it can update the location portion of its
context information stored in the network. If a mobile device moves
from one cell to another in the network it updates the context
information, so that the network knows how to reach it for incoming
calls or incoming data. Where the device is a low (or no) mobility
MTC device, such as a meter or sensor affixed to a structure, there
is less likelihood that the device will move from one cell to
another. As a result, as long as the last known position is stored
there is a low to zero probability that the device will need to
report a new location.
[0031] To take advantage of this lack of mobility, a new UE state
can be defined, and is hereinafter referred to as a SLEEP or
SLEEPING state. One skilled in the art will appreciate that the
name of the state can be varied in different implementations
without departing from the scope of the present invention.
Furthermore, it should be clear that this is a network state, so
that the network views the device as sleeping, not a device state
that is entered into to reduce power consumption, although it is
understood that when the network status is step to SLEEPING, it is
likely that the device will enter a sleep mode to conserve
power.
[0032] In the SLEEPING state, the context information associated
with the device is largely discarded by conventional network
elements. The location information associated with the device that
is stored in the context information is maintained, but is
offloaded to an MTC tracking server. Any remaining context
information can be discarded (although one skilled in the art will
appreciate that keeping other information would not necessarily
depart from the scope of the present invention). The UE, at this
time, can receive an indication from the network that the network
has assigned it a sleep state. This may result in the UE suspending
or terminating resident applications to enter a power saving mode,
although it may be preferable for the device to monitor the radio
paging channel. If the UE detects that is has changed cells, or
otherwise has non-signaling data to transmit, it can do so, but
otherwise it will create no signaling traffic.
[0033] Because of the low signaling traffic associated with the
SLEEPING device, the SLEEPING state shares many traits with the
DEREGISTERED state. Effectively the resources allocated to a device
can be largely released when the device enters the SLEEPING
state.
[0034] As noted above, the location data for a device in the
REGISTERED but SLEEPING state can be maintained in another node,
herein referred to as the MTC tracking server. One skilled in the
art that the MTC tracking server can be implemented, as shown in
FIG. 1 as a separate element, and may be geographically distant
from other network elements. Alternatively it can be implemented as
part of the existing network elements such as the Mobility
Management Entity, the Servicing Network Gateway, or the Packet
Data Network Gateway. As shown in FIG. 1, any MTC device 100
connects to the network and interacts with the Mobility Management
Entity (MME) 102. The MME 102 connects to the Servicing Network
Gateway (SGW 104), the Tracking Area Update server 110, and the
Home Subscriber Server 112. The SGW 104 provides a connection to
the Packet Data Network Gateway (PGW 106), which in turn provides a
connection to the MTC Tracking server 108. The MTC tracking server
108 is used to keep the UE context that was received and stored by
the network prior to the last Sleep mode tracking area update (TAU)
procedure, or Sleep Request procedure. The MTC tracking server 108
can enable new functions related to its role, such as: Sleep
Request, Sleep mode TAU, Sleep mode Detach, Wake-up Request, and
Wake-up Paging. The MTC tracking server 108 may also be connected
to the TAU server 110 so that they can directly exchange data
instead of routing their messaging through other nodes.
[0035] The state of a device, as tracked by the network, can be
understood in the context of a state change diagram such as that
illustrated in FIG. 2. The UE can take on a state such as
DE-REGISTERED 120, REGISTERED 122, CONNECTED 124, IDLE 126 AND
SLEEPING 128. A standard network attach or detach operation can be
used to move a UE between a DEREGISTERED state 120 and a REGISTERED
state 122 and vice versa. Once REGISTERED 122, the existence of
data traffic determines the movements between CONNECTED 124 and
IDLE 126. From the REGISTERED state 122, a sleep request function
can move the UE into SLEEPING state 128, while a wakeup procedure
can move the SLEEPING state 128 to a REGISTERED state 122. From a
SLEEPING state 128, a sleep mode TAU will leave the state
unchanged, but a sleep mode detach message can move the state to
DEREGISTERED 120.
[0036] FIG. 3 illustrates an exemplary embodiment of a method of a
device changing to a network sleep state. The process starts in
step 159, with the UE REGISTERED. When the UE is in the REGISTERED
or IDLE states it has a full complement of context information, and
being an MTC device, it is likely to not move. The MTC UE can then
send a Sleep Request to the MME in step 152. This request notifies
the MME that the UE is entering a state in which it is unlikely to
generate data traffic, and is not likely to leave the current
location in the network. At least a portion of the UE context is
then uploaded to the MTC tracking server for storage in step 154.
In a presently preferred embodiment, the MTC tracking server will
notify the MME that the request has been processed in step 156, and
reply to the UE with a Sleep Request Ack message in step 158. The
MME can then begin deallocating network resources associated with
the UE in step 160. This may include releasing the UE context in
the SGW/PGE through the use of a Delete Bearer Request Message. The
MME then removes the UE context that it stores and the UE can
switch into a device sleep state.
[0037] While in SLEEP mode, a TAU procedure can be triggered if the
UE is moved into a new tracking area. In one embodiment of a system
of the present invention, there is no periodicity specified for a
TAU while the UE is in the SLEEPING State. One exemplary method for
handling such a process is illustrated in FIG. 4. The process
begins in step 162 when the UE is in its sleep mode. When the UE
moves into a new tracking area in step 164, it generates a Sleep
mode TAU request that is sent to the MME in step 166. The detection
of a new tracking area can be performed using any of a number of
techniques including an analysis of the signals received on the
radio paging channel. The Sleep Mode TAU Request can be a
relatively lightweight message to reduce signaling load, and as
such may contain only a few parameters such as a UE identifier (UE
ID). The location context can be derived by the network from the
cell or base-station through which the Sleep Mode TAU is received.
At this point the MME does not have any context associated with the
UE and calculates a new Track Area list in step 168. The Sleep Mode
TAU message with the UE ID and the new track area list is then sent
to the MTC Tracking server in step 170. The MTC tracking server can
then update its UE context with the new information, and
acknowledge receipt of the message to the MME. The MME can respond
to the UE with the new track area list in step 172. The UE can save
the received track area list and remain in SLEEPING state.
[0038] When the UE needs to be reached, a Wake-up Paging procedure
can be employed, as illustrated in FIG. 5. This is typically used
when there a message in the network that should be sent to the MTC
UE. The UE state is determined to be SLEEPING, and as such the
network elements will request the UE context from the MTC Tracking
Server. In step 174, the MTC tracking server receives the paging
request. The MTC tracking server can generate a Wake-up Paging
message that includes the UE context in step 176, and forward the
generated message to the appropriate MME in step 178. The MME can
then page the UE in the tracking areas identified in the UE context
of the message. The UE, though it is sleeping, is monitoring the
radio paging channel and will detect the paging message. Upon
detecting a paging message addressed to itself, the UE will wake up
and respond to any Service Request procedure. If needed, a PDN
connection can be established between the UE and the MTC
server.
[0039] While the above procedure allows a device connected to the
mobile network to cause the UE to wake up, a procedure for the UE
to wake up on its own is also provided in FIG. 6. From the sleeping
state of step 180, the UE can perform a Wake-Up Request procedure
when it has a need to transmit data traffic. The UE generates a
Wake-Up Request message and transmits the generated message to the
MME on the radio access channel in step 182. The MME can then
retrieve the UE context from the MTC Tracking Server in step 184.
This allows the MME to avoid consuming the radio access channel
resources in a determination of a context for the essentially
unknown UE. The MME then replies to the UE with an Ack message in
step 186. At this point the UE is back to a REGISTERED state and
can then perform the Service Request procedure and establish a new
PDN connection.
[0040] A UE that is already in Sleep mode can also be provided with
a path directly to the detached state as shown in FIG. 7. Use of
this method can obviate the need to wake up the device only to
allow it to detach. From the SLEEPING state of step 188, the UE can
issue a Sleep Mode Detach request to the MME that will allow it to
detach from the network in step 190. To reduce the signaling load,
the request can contain minimal information, such as only a UE ID.
In response to receipt of the message of step 190, the Sleep Mode
Detach request is sent to the MTC tracking Server in step 192. The
MTC tracking server, in step 194, removes the UE context and
provides an acknowledgement to the MME in step 196. The MME can
then provide the confirmation to the UE at which point the UE will
be detached.
[0041] The above methods, and the use of an MTC tracking server and
the network based SLEEP state, can reduce unnecessary signaling as
the device moves between the different states illustrated in FIG.
2. The signaling can also be reduced through the use of the Sleep
mode TAU procedure. Resources in the network can be re-allocated by
storing the context information of Sleeping MTC UE in the MTC
Tracking Server. Existing devices and infrastructure need not
support the new protocols to interact with infrastructure and
devices that do, thus allowing the opportunity to offer backward
and forward compatibility which limits the impacts on existing
infrastructure. The communications of MTC devices can be improved
while the load that such communications place on the network can be
ameliorated. These methods and systems also allow for
differentiated MTC device and conventional UE device communications
handling which will diminish the impact on legacy
implementations.
[0042] FIG. 8 illustrates a generic node of the instant invention.
Node 200 includes a processor 202, storage 204, and network
interfaces 206 and 208 which may be implemented as a single
interface in some nodes. In the MTC UE, it should be noted that
only one network interface is required, and it is typically a radio
air interface. For the MME, the storage can be used to store the UE
context prior to offloading it to the MTC tracking server. In the
MTC server, the storage is used to maintain the context information
offloaded by the MME. One skilled in the art will appreciate that
in each node, the storage can also be used to store machine
readable instructions that allow the processor to execute the
method outlined in the above figures.
[0043] Embodiments of the invention may be represented as a
software product stored in a machine-readable medium (also referred
to as a computer-readable medium, a processor-readable medium, or a
computer usable medium having a computer readable program code
embodied therein). The machine-readable medium may be any suitable
tangible medium including a magnetic, optical, or electrical
storage medium including a diskette, compact disk read only memory
(CD-ROM), digital versatile disc read only memory (DVD-ROM) memory
device (volatile or non-volatile), or similar storage mechanism.
The machine-readable medium may contain various sets of
instructions, code sequences, configuration information, or other
data, which, when executed, cause a processor to perform steps in a
method according to an embodiment of the invention. Those of
ordinary skill in the art will appreciate that other instructions
and operations necessary to implement the described invention may
also be stored on the machine-readable medium. Software running
from the machine-readable medium may interface with circuitry to
perform the described tasks.
[0044] The above-described embodiments of the present invention are
intended to be examples only. Alterations, modifications and
variations may be effected to the particular embodiments by those
of skill in the art without departing from the scope of the
invention, which is defined solely by the claims appended
hereto.
* * * * *