The present invention generally relates to packet mobile communication
networks and systems.
Descriptions of packet mobile networks and systems can be found in the
literature, such as in particular in Technical Specifications published by
standardization bodies such as for example 3GPP (3rd Generation Partnership
Project).
An example of packet mobile system is EPS (Evolved Packet System). An
EPS network comprises a Core Network called EPC (Evolved Packet Core) that can
be accessed via different access networks including E-UTRAN access or
GERAN/UTRAN access. EPC nodes in particular include Mobility Management
Entity (MME) for E-UTRAN access, Serving GPRS Support Node (SGSN) for
GERAN/UTRAN access, Serving Gateway (SGW) and PDN Gateway (PDN GW).
EPS is specified in particular in 3GPP TS 23.401 for E-UTRAN access and in 3GPP
TS 23.060 for GERAN/UTRAN access. An example of architecture for EPS is
recalled in figure 1 taken from 3GPP TS 23.401 .
In a system such as EPS, a User Equipment (UE) may communicate with
various applications in various external networks (also referred to as Packet Data
Network PDN), via an EPS network providing communication services, including
providing connectivity (referred to as PDN connectivity, or IP connectivity) between
the UE and a PDN represented by a PDN identifier such as Access Point Name
APN.
Mobile terminated communications towards UEs in idle mode are
supported in a system such as EPS via a network triggered service request
procedure, defined in 3GPP TS 23.401 .
Optimizations or enhancements are now introduced in such networks and
systems, for the support of new types of communications having new service
requirements, such as Machine Type Communications (MTC) also known as
Internet of Things (loT).
An example of such new service requirements is that mechanisms should
be provided for MTC Device triggering, allowing the network to trigger a MTC Device
(or UE equipped for MTC) to initiate communication with a MTC Server based on a
trigger indication received from the MTC Server.
Mechanisms for Device triggering are described in particular in 3GPP TS
23.682 specifying architecture enhancements to facilitate communications with
packet data networks and applications. An example of triggering flow over user
plane, wherein a DT-AS (Device Trigger Application Server) delivers the trigger to
the UE over the user plane, is recalled in figure 2 taken from 3GPP TS 23.682,
Annex D, Figure D-1 . Triggering over control plane (using Short Message Service
SMS) is also described in 3GPP TS 23.682.
Another example of such new service requirements is that mechanisms
should be provided to lower the power consumption of MTC Devices.
An example of mechanism to lower the power consumption of Devices (or
User Equipments), called UE Power Saving Mode (PSM) is specified in particular in
3GPP TS 23.682 and 3GPP TS 23.401 . A UE may adopt the PSM for reducing its
power consumption. That mode is similar to power-off, but the UE remains
registered with the network and there is no need to re-attach or re-establish PDN
connections. A UE in PSM is not immediately reachable for mobile terminating
services. A UE using PSM is available for mobile terminating services only for the
period of an Active Time after a mobile originated event like data transfer or
signalling, e.g. after a periodic TAU/RAU (Tracking Area Update/Routing Area
Update) procedure.
Another example of mechanism to lower the power consumption of Devices
(or User Equipments), called Extended DRX (Discontinuous Reception) is
considered in particular in 3GPP TR 23.887. A UE with extended DRX applies
longer period of discontinuous reception, up to several minutes, between the times
when it wakes up to listens to possible paging occurences.
As recognized by the inventors, and as will be explained with more detail
later, there is a need to improve the support of mobile-terminated communication
(such as Device Triggering) towards an UE in idle mode using a power saving
mechanism whereby the UE is transiently non reachable (examples of such power
saving mechanism including, though not limited to, Power Saving Mode or Extended
DRX). For example, there is a need to avoid network load increase due to deletion
of DL (Downlink) packets towards an UE in PSM mode, causing DL packet
retransmissions by retransmission schemes on higher layers. There is also a need
to improve reachability of UEs in idle mode using such power saving mechanism.
As also recognized by the inventors, there is a need to improve the support
of Mobile Terminated SMS for a User Equipment UE using extended DRX.
As also recognized by the inventors, there is a need to improve the support
of Mobile Terminated Location Request towards a User Equipment UE using a
power saving mechanism whereby the UE is transiently not reachable (examples of
such power saving mechanism including, though not limited to, Power Saving Mode
or Extended DRX).
Embodiments of the present invention in particular address such needs.
These and other objects are achieved, in one aspect, by a method for
support of mobile-terminated communication in an Evolved Packet System, towards
a User Equipment UE in idle mode using a power saving mechanism whereby said
UE is transiently not reachable, said method comprising:
- allowing one or more Downlink DL packets received for said UE to be
buffered in a Serving Gateway SGW, upon request, for up to a duration referred to
as DL buffering duration.
These and other objects are achieved, in another aspect, by a method for
support of Mobile Terminated SMS for a User Equipment UE in idle mode using
extended DRX, said method comprising:
- upon receipt of said Mobile Terminated SMS, a Mobility management
Entity MME or a Serving GPRS Support Node SGSN serving said UE immediately
reporting towards a Short Message Service Centre SMSC that the UE is not
reachable, and paging the UE,
- upon receipt of a paging response from the UE, the MME or the SGSN
alerting the SMSC via the HSS to trigger the SMSC to re-send the SMS.
These and other objects are achieved, in another aspect, by a method for
support of Mobile Terminated Location Request towards a User Equipment UE
using a power saving mechanism whereby the UE is transiently not reachable, said
method comprising:
- upon receipt of a network initiated location request from a Gateway Mobile
Location Centre GMLC, a Mobility management Entity MME or a Serving GPRS
Support Node SGSN, serving said UE immediately returning an answer towards the
GMLC containing a last known location for the UE, with an indication that the UE is
transiently not reachable, and paging the UE if the UE is using extended DRX,
- upon receipt of a paging response from the UE or upon the next signalling
activity for the UE, the MME or the SGSN sending towards the GMLC a Subscriber
Location Report.
These and other objects are achieved, in other aspects, by entities
configured for performing at least one step of such method(s), said entities
including, in particular (though not exclusively) in an EPS network: Serving Gateway
SGW, Mobility Management Entity MME, Serving GPRS Support Node SGSN,
Home Subscriber Server HSS.
Some embodiments of apparatus and/or methods in accordance with
embodiments of the present invention are now described, by way of example only,
and with reference to the accompanying drawings, in which:
- Figure 1 is intended to recall an example of EPS architecture,
- Figure 2 is intended to recall an example flow for user-plane device
triggering,
- Figure 3 is intended to illustrate an example flow for user-plane device
triggering towards an UE in idle mode using a power saving mechanism whereby
the UE is transiently not reachable, according to embodiments of the present
invention,
- Figure 4 is intended to illustrate an example flow for Tracking Area Update
TAU procedure with an SGW change, for support of mobile terminated
communication towards an UE in idle mode using a power saving mechanism
whereby the UE is transiently not reachable, according to embodiments of the
present invention, whereby the Downlink DL packet(s) buffered at the old SGW are
forwarded to the new SGW;
- Figure 5 is intended to illustrate an example flow for Mobile Terminating
Short Message for UE with extended DRX, according to embodiments of the present
invention,
- Figure 6 is intended to illustrate an example flow for Mobile Terminating
Location Request towards an UE in idle mode using a power saving mechanism
whereby the UE is transiently not reachable, according to embodiments of the
present invention.
The description below is made by way of example for a mobile system
corresponding to 3GPP Evolved Packet System EPS. It should however be
understood that some embodiments of the present invention are not limited to
3GPP EPS.
The Internet-of-Things (loT) is a concept where many things (e.g., devices)
can be uniquely identified and communicated with. One study forecasted that the
number of devices representing the loT will grow to 26 Billion units by 2020. Many of
these devices will be constrained in terms of low-cost, low-energy and low-bitrate.
3GPP has specified a new Power Saving Mode feature (PSM) in Release
12 (see 3GPP TS 23.401 and 23.682), whereby the UE enters long sleep periods
during which the UE remains registered in the network but is no longer reachable.
3GPP is further considering extending the DRX period (discontinuous reception
period, i.e. the period at which the UE may receive paging requests from the
network) of UEs in idle mode in Release 13, to several minutes (e.g. 5 , 10 or 15
minutes) to provide more battery saving gains for UEs which require to support
Mobile Terminated data communications. See for example document 3GPP S2-
143324 .
Mobile terminating data communications towards UEs in PSM or with an
extended DRX period would be inefficient in many aspects with the current network
behaviour, which is reminded below:
- When downlink data is sent to a UE that is in ECM-IDLE mode, at
least one IP packet is buffered in the SGW and the UE is paged. When the
UE responds to the paging, the buffered IP packets are transmitted to the
UE.
- When downlink data is sent to a UE that is in ECM-IDLE mode and
is applying a sleep mode function e.g. PSM, the IP packets are discarded in
the SGW. No paging is done of the UE.
Issues the packet discard behaviour of the current system may lead to
include:
- Higher load on the network, caused by the retransmission
schemes applied by transport or application protocols to ensure a successful
transmission of packets (e.g. causing additional Downlink Data Notification
signalling from SGW to MME/SGSN, requiring additional resources at the
sender/application server side, sender side falling back to SMS-based device
triggering via the Tsp interface after retransmission timeout causing
additional signalling and processing in the entire network);
- Difficulty to reach devices that use power saving mechanisms, that
could make cellular a less preferred choice for Internet-of-Things and MTC
applications.
The very large number of such devices makes it especially important that
the 3GPP access is efficient when accessing these constrained devices. 3GPP is
thus in the process of studying optimizations to the EPS to support Mobile
Terminated data communications with UEs (devices) which are not reachable for a
long period (e.g. several minutes or more). Applications at the network side may
trigger the devices using the Tsp reference point (towards an MTC-IWF) and SMSbased
delivery mechanisms, as per 3GPP TS 23.682. But this would entail very
inefficient downlink data transmission, due to excessive signalling and processing in
many network entities (MTC-IWF, HSS, SMS Service Center, MME, SGSN, MSC) to
trigger the device via SMS upon every downlink data communication. In the case of
extended DRX to be up to 5 minutes, also, it is in principle efficient to have the data
ready in the SGW for DL delivery rather than just trigger by SMS.
There is a need for a different approach, in particular avoiding abovementioned
drawbacks. Embodiments and/or aspects of the invention in particular
address such needs.
Some embodiments and/or aspects of the invention, related to support of
mobile terminated communication (e.g. device triggering) towards a UE in idle mode
using a power saving mechanism whereby the UE is transiently not reachable (e.g.
UE in PSM or using Extended DRX), are based on following ideas:
In situations where the UE's IP connectivity is established (i.e the UE has
already established a PDN connection), the UE IP address is known and a NAT or
firewall isn't blocking downlink packet transmission, the applications on the network
side trigger the device via the established IP connectivity (i.e. PDN connection), and
with the SGW being instructed by the MME/SGSN to store the DL user plane packet
(encapsulating the device trigger request) for up to a duration covering one or more
DRX periods of the UE. Also, this may work for PSM (power saving mode) by
indicating a storage period equal to the PSM periodic TAU or RAU value sent to the
UE.
Some embodiments and/or aspects of the invention, related to support of
mobile terminated communication (e.g. device triggering) towards a UE in idle mode
using a power saving mechanism whereby the UE is transiently not reachable (e.g.
UE in PSM or using Extended DRX), will now be described in connection with the
example flow of figure 3 .
When desiring to initiate data communication with a UE making use of a
power saving mechanism (e.g. PSM or extended DRX), the application (at the
network side) may send a device trigger request to the UE:
a) by sending a downlink user plane packet towards the IP address
of the UE, optionally via an intermediate SCS (Service Capability Server)
that acknowledges receipt of the packet, if IP connectivity is available
(normal case); as per figure D-1 of 3GPP TS 23.682.
b) or using the Tsp and SMS delivery mechanism otherwise (as per
subclause 5.2.1 of TS 23.682)
Note 1: use of device triggering for UEs in extended DRX mode is
new.
In some embodiments, one or more of following steps may be provided,
referring to the example flow of figure 3 .
Some of these steps may require modifications to be introduced in the
network triggered service request procedure (as defined in particular in 3GPP TS
23.401).
The PGW forwards the DL user plane packet to the SGW over the S5/S8-U
bearer, per existing procedures.
Upon receipt of the DL user plane packet (encapsulating the device
trigger), the SGW sends a Downlink Data Notification (DDN) request to the MME or
SGSN (depending on whether the UE is under E-UTRAN or UTRAN/GERAN
coverage), per existing procedure.
Based on operator policies (e.g. user's subscription, the APN for which a
DL packet was received), if the UE has negotiated with the network the use of a
power saving mechanism (e.g. PSM, extended DRX), the MME/SGSN decides
whether to proceed with the DDN request (normal case) or reject it.
When proceeding with the request, the MME or SGSN initiates the Network
Triggered service request procedure (as specified in TS 23.401 subclause 5.3.4.3
and TS 23.060), i.e. sends a paging request towards eNBs or RNCs pertaining to
the desired paging area. The eNBs or RNCs store the paging request until the next
paging occurrence of the UE. As an exception for UEs in PSM mode, the
MME/SGSN does not page the UE (cf step 3 in Figure 5.3.4.3-1 of TS 23.401) but
waits for the next uplink signalling activity of the UE (e.g. next periodic TAU/RAU
request) to trigger the Service Request procedure (step 5 and following steps).
Note 2 : UEs do not listen to paging channels when in PSM.
In the Downlink Data Notification Acknowledge, the MME or SGSN
indicates to the SGW that the UE is "transiently not reachable" (e.g. new value of
the Cause IE in DDN Acknowledge message, see 3GPP TS 29.274 subclause
7.2.1 1.2) and provides the SGW with the duration up to which the SGW can buffer
the downlink packets for that UE (via a new DL Buffering Duration IE added to the
DDN Acknowledge message). This duration is set such as to cover the duration of
one or more DRX periods for a UE with extended DRX OR the PSM specific
periodic TAU/RAU value for a UE in PSM.
Note 3 : "more DRX periods" aims at accommodating cases where
paging the UE at its first DRX occurrence would fail (e.g. UE not reachable
or paging channel overload).
Note 4 : for UEs in PSM, the MME/SGSN may estimate a shorter
buffering time in the SGW based on the periodic TAU/RAU timer and the
time elapsed since the last UE signalling procedure.
The DDN Acknowledge message to the SGW may also contain a limit to
the number of buffered DL packets per PDN connection or per UE for the UE (there
can be a per UE or per APN subscription to the buffering - if a APN has zero set for
buffering, then the SGW discards DL data for this APN PDN connection when the
device is transiently not reachable). If subsequent DL data arrives after this
notification, no more DDN is triggered and data is stored up to the indicated packets
limit.
Note 5 : the SGW may alternatively be configured with the limit to
the number of buffered DL packets per APN and/or per UE.
The MME/SGSN may determine whether the SGW supports the extensions
defined by this invention by configuration, or e.g. by the SGW notifying support of
this feature/extensions via GTP-C signalling to MME/SGSN (using the existing
feature discovery mechanism, see 3GPP TS 29.274 clause 11).
Upon receipt of that response, the SGW buffers the downlink packets
received for that UE until either the UE responds to the paging request (UE with
extended DRX) or triggers any uplink signalling (UE with extended DRX or PSM)
and establishes downlink user radio and S1-U bearers, as per the existing Service
Request procedure (see TS 23.401 subclause 5.3.4.3 and 23.060), or the duration
provided by the MME/SGSN elapses (in which case the SGW drops the DL packets
for that UE), whichever occurs first. In the former case, user plane exchanges can
then take place between the UE and the application at the network side.
When rejecting the request, the MME or SGSN sends a Downlink Data
Notification Acknowledge with the indication that the UE is not reachable (per
existing procedure). The SGW then drops the downlink packets and ceases to send
downlink data notification requests for subsequent DL user packets received during
a given period.
Some embodiments and/or aspects of the invention are related to a
Tracking Area Update or Routing Area Update procedure for support of mobile
terminated communication (e.g. device triggering) towards an UE in idle mode using
a power saving mechanism whereby the UE is transiently not reachable (e.g. UE in
PSM or using Extended DRX). Such embodiments and/or aspects of the invention
will now be described in connection with the example flow of figure 4 , by way of
example for the TAU procedure. Though not illustrated by a specific example flow,
such embodiments and/or aspects of the invention also apply to the Routing Area
Update RAU procedure.
In some embodiments, one or more of following steps may be provided,
referring to the example flow of figure 4 .
Some of these steps may require modifications to be introduced in the
Tracking Area Update TAU procedure (as defined in particular in 3GPP TS 23.401).
Though not illustrated, similar modifications may require to be introduced in the
Routing Area Update RAU procedure (as defined in particular in 3GPP TS 23.401 or
3GPP TS 23.060).
If the UE initiates an intra MME Tracking Area Update (TAU) or intra
SGSN Routing Area Update (RAU) (i.e. UE moving to a new Tracking Area /
Routing Area) before responding to paging, the MME or SGSN leverages the
signalling connection used for the TAU/RAU signalling to establish DL connectivity
at that time to transfer DL packets (as per existing procedure - TS 23.401
subclause 5.3.4.3: " If the MME already has a signalling connection over S1-MME
towards the UE but the S1-U tunnel has not yet been established, then the
messages sequence performed start from the step when MME establishes the
bearer(s).")
Upon an inter-MME TAU or inter-SGSN TAU, i.e. when the UE moves to a
different CN node, the new MME or SGSN behaves as per existing TAU or RAU
procedure (see e.g. TS 23.401 subclause 5.3.1); during that procedure, the new
MME or SGSN takes over the control of the SGW, by sending a GTP-C Modify
Bearer Request to the SGW (e.g. see step 9 of TS 23.401 Figure 5.3.3.1 - 1 ) . The
SGW then sends a new Downlink Data Notification to the new MME/SGSN if DL
data are still buffered in the SGW for that UE.
If the UE does a TAU/RAU which requires an SGW change, if the
MME/SGSN has requested the old SGW to buffer some data, the MME/SGSN
requests the new SGW to provide a GTP-U IP@/TEID for DL data forwarding, to
allow the old SGW to forward the buffered DL packets to the new SGW. E.g. taking
the example of a TAU with SGW change (see TS 23.401 subclause 5.3.3.1 ) , the
MME requests the new SGW in the Create Session Request (step 8 , new IE) to
provide an IP@ and TEID for DL data forwarding, which the new SGW provides in
the Create Session Response (step 11 - new IE). The MME passes on the new
SGWs IP@ and TEID to the old SGW in the Delete Session Request (step 18, new
lEs). The old SGW forwards any DL buffered packets to the new SGW, and once
done, send one or more GTP-U End Markers packets (existing message, see TS
29.281) to inform the new SGW that no new DL packets need to be forwarded.
In inter-MME/SGSN Inter-SGW mobility scenario, the old MME/SGSN indicates in
the Context Response message whether DL data needs to be forwarded to the
target SGW, and if so, the new MME/SGSN passes on the new SGW IP@ and TEID
for DL data forwarding in the Context Acknowledge (e.g. step 7 in TS 23.401
subclause 5.3.1 , which shall then take place after step 11).
Note 6 : Handover scenarios already support transfer of DL packets
from old to new SGW. See e.g. TS 23.401 subclause 5.5.1 .2.2 steps 6 and
8 . See also TS 29.281 subclause13.2. DL data forwarding is currently not
supported though for TAU/RAU, but is added as part of embodiments and/or
aspects of the invention.
Some embodiments and/or aspects of the invention, related to support of
Mobile Terminated SMS for a User Equipment UE in idle mode using extended
DRX, will now be described in connection with the example flow of figure 5 . The
Short Message Service (SMS) for EPS network supported via "SMS in MME" is
considered by way of example in figure 5 .
In some embodiments, a serving node MME or SGSN is enhanced to
support delivery of SMS for UEs in idle mode using extended DRX, based on one or
more of following steps.
Upon receipt of a Mobile Terminated SMS (as illustrated at step 3), the
MME or SGSN pages the UE at once (as illustrated at step 4), and responds to the
SMSC (as illustrated at step 5) that the UE is not reachable and that the SMSC will
be alerted at the next activity of the UE (such response can use existing procedures,
see TS 23.272 Annex C.6, with MME setting the Mobile-Not-Reachable flag).
The eNB then pages the UE at a next UE's paging occurrence, as
illustrated at step 8 .
Upon receipt of the paging response (during a service request procedure)
or upon uplink signaling activity, as illustrated at step 9 , the MME or SGSN alerts the
SMSC via the HSS to trigger the SMSC to re-send the SMS as illustrated at step 10
(per existing procedures, see TS 23.272 Annex C.6, i.e. with e.g. MME sending a
Ready for SM message to the HSS and the HSS triggering the SMS alert procedure
as defined in TS 23.040).
Some embodiments and/or aspects of the invention, related to support of
Mobile Terminated Location Request towards a UE in idle mode using a power
saving mechanism (such as Power saving Mode PSM or Extended DRX) whereby
the UE is transiently not reachable, will now be described in connection with the
example flow of figure 6 .
Some of these steps may require modifications to be introduced in the
Mobile Terminating Location Request procedure (as defined by 3GPP TS 23.271).
In some embodiments, a MME or SGSN is enhanced to support EPC
Mobile Terminated Location Request (see TS 23.271 , subclause 9.1 .15) towards
UEs using a power saving mechanism, based on one or more of following steps.
Upon receipt of a network initiated location request from a GMLC (Provide
Subscriber Location Request), the MME or SGSN returns an answer (Provide
Subscriber Location Response) immediately to the GMLC, containing the last known
location, with the optional indication that the UE is "transiently not reachable". If this
optional indication is set, the MME or SGSN also stores the address of the GMLC.
The MME/SGSN also pages the UE if the UE is using extended DRX. Upon
receipt of the paging response from the UE, or upon the next uplink signalling
activity for a UE (for UEs using extended DRX or PSM), the MME or SGSN sends a
Subscriber Location Report (with the UE's current location) to the GMLC (as if this
was an EPC network induced Location Request, see TS 23.271 subclause 9.1 .17;
or TS 29.172 subclause 6.3.2). This assumes the GMLC has indicated support of
this new procedure ("deferred location report supported") in the original Provide
Subscriber Location Request.
If the UE moves to another MME/SGSN change prior to reporting the
location to the GMLC, the old MME/SGSN sends a Subscriber Location Report to
the GMLC with the indication that it cannot proceed with the request as a result of
UE mobility. The GMLC may reiterate then its request towards the new MME/SGSN.
It is assumed that UEs configured with power saving mechanisms do not
use dedicated EPS bearers (e.g. this is the case of MTC communications), and thus
any PGW initiated signalling (e.g. GTP-C Create Bearer Request) received by the
MME or SGSN for such UEs are rejected. Note that otherwise, it would also be
possible for the MME/SGSN to reject the request with the indication that the UE is
transiently not reachable, and to wake up the PGW by sending a Modify Bearer
Request message when the UE responds to the page request to let the PGW know
that the UE is reachable.
Some embodiments and/or aspects of the invention enable to support
efficient downlink data communication in EPS for UEs or devices configured with
power saving mechanisms, e.g; Power Saving Mode or extended DRX period.
Especially for applications constrained by cost and low operator ARPU, it should be
preferential to avoid high usage of SMS based device triggering for a large number
of MTC devices.
Some embodiments and/or aspects of the invention present the following
main benefits:
- minimum impacts for 3rd party applications and EPS
- require minimum buffering in the EPC (just the device triggers), since
application does not start downlink data transfers until getting the trigger response
from the UE
- no buffering of other applicative packets that may be worthless to buffer
anyway (e.g. TCP).
In one aspect, there is provided a method for support of mobile-terminated
communication in an Evolved Packet System, towards a User Equipment UE in idle
mode using a power saving mechanism whereby said UE is transiently not
reachable.
Various embodiments are provided, which may be taken alone or in
combination, according to various combinations, including (though not limited to)
following embodiments.
In an embodiment, said method comprises:
- allowing one or more Downlink DL packets received for said UE to be
buffered in a Serving Gateway SGW, upon request, for up to a duration referred to
as DL buffering duration.
In an embodiment, said method comprises:
- a serving MME or a serving SGSN sending said request to said SGW,
such as in a Downlink Data Notification Acknowledge message or in a Downlink
Data Notification Failure Indication message.
In an embodiment:
- said request includes one or more of: an indication that said UE is
transiently not reachable, said DL buffering duration, a limit to the number of
buffered DL packets for the UE or per Packet Data Network PDN connection for the
UE.
In an embodiment:
- said buffering is controlled via user's subscription data stored in a Home
Subscriber Server HSS or via the serving MME or SGSN's operator's policy
configured in said serving MME or SGSN.
In an embodiment, said method comprises:
- upon TAU, respectively RAU, requiring a change of Serving Gateway
SGW, from an old SGW to a new SGW, allowing said one or more DL packets
buffered in the old SGW to be forwarded to the new SGW.
In an embodiment, said method comprises:
- upon TAU, respectively RAU, requiring a change of Serving Gateway
SGW, from an old SGW to a new SGW, a serving MME, respectively SGSN,
requesting the new SGW, such as in a Create Session Request message, to
provide addressing information for forwarding of said one or more buffered DL
packets from said old SGW to said new SGW.
In an embodiment, said method comprises:
- upon TAU, respectively RAU, requiring a change of Serving Gateway
SGW, from an old SGW to a new SGW, the new SGW providing to a serving MME,
respectively SGSN, such as in a Create Session Response message, addressing
information for forwarding of said one or more buffered DL packets from said old
SGW to said new SGW.
In an embodiment, said method comprises:
- upon TAU, respectively RAU, requiring a change of Serving Gateway
SGW, from an old SGW to a new SGW, a serving MME, respectively SGSN,
providing to the old SGW, such as in a Delete Session Request message,
addressing information for forwarding of said one or more buffered DL packets from
said old SGW to said new SGW.
In an embodiment, said method comprises:
- upon TAU, respectively RAU, requiring a change of Serving Gateway
SGW, from an old SGW to a new SGW, the old SGW forwarding said one or more
buffered DL packets to the new SGW, and once done, sending one or more GTP U
End Markers Packets.
In an embodiment, said method comprises:
- upon TAU, respectively RAU, requiring a change of Serving Gateway
SGW from an old SGW to a new SGW, and a change of serving node from an old
MME or old SGSN to a new MME, respectively a change of serving node from an
old MME or old SGSN to a new SGSN, the old MME or old SGSN sending to the
new MME, respectively to the new SGSN, such as in a Context Response message,
an indication that forwarding of said one or more buffered DL packets from said old
SGW to said new SGW is required.
In an embodiment, said method comprises:
- upon TAU, respectively RAU, requiring a change of Serving Gateway
SGW from an old SGW to a new SGW, and a change of serving node from an old
MME or old SGSN to a new MME, respectively a change of serving node from an
old MME or old SGSN to a new SGSN, the new MME, respectively the new SGSN,
passing to the old MME or old SGSN, such as in a Context Acknowledge message,
addressing information for forwarding of said one or more buffered DL packets to
the new SGW.
In an embodiment, said method comprises:
- a Serving Gateway SGW signalling to a serving MME or to a serving
SGSN its support of said buffering, such as via GTP-C signalling.
In an embodiment, said method comprises:
- a serving MME or a serving SGSN determining if a Serving Gateway
SGW supports said buffering.
In an embodiment, said method comprises:
- a serving MME or a serving SGSN deciding, based on configured
operator's policy or user's subscription data received from a Home Subscriber
Server HSS, whether or not to reject a Downlink Data Notification Request sent by a
Serving Gateway SGW for a UE using a power saving mechanism.
In an embodiment, said method comprises:
- in the case of a power saving mechanism corresponding to Extended
DRX, allowing said buffering until either the UE responds to a paging request, or
said DL buffering duration covering one or more DRX periods elapses, whichever
occurs first.
In an embodiment, said method comprises:
- in the case of a power saving mechanism corresponding to Power Saving
Mode PSM, allowing said buffering until either the UE triggers any uplink signalling,
or said DL buffering duration covering the UE's periodic TAU or RAU timer optionally
reduced by the time elapsed since the last UE signalling procedure, whichever
occurs first.
Other aspects relate to entities for performing related step(s) of such
method, said entities including, in particular (though not exclusively), in an EPS
network: Serving Gateway SGW, Mobility Management Entity MME, Serving GPRS
Support Node SGSN, Home Subscriber Server HSS.
In an aspect, there is provided a Mobility management Entity MME, or a
Serving GPRS Support Node SGSN, configured to, in an embodiment:
- send to a Serving Gateway SGW, such as in a Downlink Data Notification
Acknowledge message, at least one of: an indication that an User Equipment UE in
idle mode served by said MME or by said SGSN is transiently not reachable, a
Downlink DL buffering duration whereby one or more Downlink DL packets received
for said UE should be buffered in said SGW for a duration up to said DL buffering
duration.
In another aspect, there is provided a Mobility management Entity MME,
respectively a Serving GPRS Support Node SGSN, configured to, in an
embodiment:
- send to a Serving Gateway SGW, during a TAU, respectively RAU,
procedure requiring a change of Serving Gateway SGW from an old SGW to a new
SGW, such as in a Create Session Request message, an indication that forwarding
of buffered Downlink DL packets from said old SGW to said new SGW is required.
In another aspect, there is provided a Serving Gateway SGW, configured
to, in an embodiment:
- send to a Mobility management Entity MME, respectively to a Serving
GPRS Support Node SGSN, during a TAU, respectively RAU, procedure requiring
a change of Serving Gateway SGW from an old SGW to said SGW referred to as
new SGW, such as in a Create Session Response message, addressing information
for forwarding of buffered Downlink DL packets from said old SGW to said new
SGW.
In another aspect, there is provided a Mobility management Entity MME,
respectively a Serving GPRS Support Node SGSN, configured to, in an
embodiment:
- send to a Serving Gateway SGW, during a TAU, respectively RAU,
procedure requiring a change of Serving Gateway SGW from an old SGW to a new
SGW, such as in a Delete Session Request message, addressing information for
forwarding of buffered Downlink DL packets from said old SGW to said new SGW.
In another aspect, there is provided a Serving Gateway SGW, configured
to, in an embodiment:
- during a TAU, respectively RAU, procedure requiring a change of Serving
Gateway SGW from said SGW referred to as old SGW to a new SGW, forward one
or more buffered DL packets to said new SGW, and once done, send one or more
GTP_U End Markers Packets.
In another aspect, there is provided a Mobility management Entity MME, or
a Serving GPRS Support Node SGSN, configured to, in an embodiment:
- upon TAU, respectively RAU, procedure requiring a change of Serving
Gateway SGW from an old SGW to a new SGW, and a change of serving node
from said MME or SGSN, referred to as old MME or SGSN, to a new MME,
respectively new SGSN, send to the new MME, respectively to the new SGSN, such
as in a Context Response message, an indication that forwarding of buffered
Downlink DL packets from said old SGW to said new SGW is required.
In another aspect, there is provided a Mobility Management Entity MME, or
a Serving GPRS Support Node SGSN, configured to, in an embodiment:
- upon TAU, respectively RAU, requiring a change of Serving Gateway
SGW from an old SGW to a new SGW, and a change of serving node from an old
MME or SGSN, to a new MME, respectively to a new SGSN, pass to said old MME
or SGSN, such as in a Context Acknowledge message, addressing information for
forwarding of buffered DL packets from said old SGW to said new SGW.
In another aspect, there is provided a Home Subscriber Server, configured
to, in an embodiment:
- store user's subscription data allowing control of buffering in a Serving
Gateway, upon request and for up to a duration referred to a DL buffering duration,
of Downlink DL packets received for a User Equipment in idle mode using a power
saving mechanism whereby said UE is transiently not reachable.
In another aspect, there is provided a method for support of Mobile
Terminated SMS for a User Equipment UE in idle mode using extended DRX.
In an embodiment, said method comprises:
- upon receipt of said Mobile Terminated SMS, a Mobility management
Entity MME or a Serving GPRS Support Node SGSN serving said UE immediately
reporting towards a Short Message Service Centre SMSC that the UE is not
reachable, and paging the UE,
- upon receipt of a paging response from the UE, the MME or the SGSN
alerting the SMSC via the HSS to trigger the SMSC to re-send the SMS.
Other aspects relate to entities for performing related step(s) of such
method, said entities including, in particular (though not exclusively), in an EPS
network: Mobility Management Entity MME, Serving GPRS Support Node SGSN.
In an aspect, there is provided a Mobility Management Entity MME or a
Serving GPRS Support Node SGSN, configured to, in an embodiment:
- upon receipt of a Mobile Terminated SMS for a User Equipment UE in idle
mode using extended DRX served by said MME or said SGSN, immediately report
towards a Short Message Service Centre SMSC that the UE is not reachable, and
page the UE,
- upon receipt of a paging response from the UE, alert the SMSC via the
HSS to trigger the SMSC to re-send the SMS.
In another aspect, there is provided a method for support of Mobile
Terminated Location Request towards a User Equipment UE using a power saving
mechanism whereby the UE is transiently not reachable.
In an embodiment, said method comprises:
- upon receipt of a network initiated location request from a Gateway Mobile
Location Centre GMLC, a Mobility management Entity MME or a Serving GPRS
Support Node SGSN, serving said UE immediately returning an answer towards the
GMLC containing a last known location for the UE, with an indication that the UE is
transiently not reachable, and paging the UE if the UE is using extended DRX,
- upon receipt of a paging response from the UE or upon the next signalling
activity for the UE, the MME or the SGSN sending towards the GMLC a Subscriber
Location Report.
Other aspects relate to entities for performing related step(s) of such
method, said entities including, in particular (though not exclusively), in an EPS
network: Mobility Management Entity MME, Serving GPRS Support Node SGSN.
In an aspect, there is provided a Mobility Management Entity MME or a
Serving GPRS Support Node SGSN, configured to, in an embodiment:
- upon receipt of a network initiated location request from a Gateway Mobile
Location Centre GMLC, immediately return an answer towards the GMLC containing
a last known location for a User Equipment UE served by said MME or SGSN, with
an indication that the UE is transiently not reachable, and page the UE if the UE is
using extended DRX,
- upon receipt of a paging response from the UE or upon the next signalling
activity for the UE, send towards the GMLC a Subscriber Location Report.
A person of skill in the art would readily recognize that steps of various
above-described methods can be performed by programmed computers. Herein,
some embodiments are also intended to cover program storage devices, e.g., digital
data storage media, which are machine or computer readable and encode machineexecutable
or computer-executable programs of instructions, wherein said
instructions perform some or all of the steps of said above-described methods. The
program storage devices may be, e.g., digital memories, magnetic storage media
such as a magnetic disks and magnetic tapes, hard drives, or optically readable
digital data storage media. The embodiments are also intended to cover computers
programmed to perform said steps of the above-described methods.

CLAIMS
1. A method for support of mobile-terminated communication in an Evolved
Packet System, towards a User Equipment UE in idle mode using a power saving
mechanism whereby said UE is transiently not reachable, said method comprising:
- allowing one or more Downlink DL packets received for said UE to be
buffered in a Serving Gateway SGW, upon request, for up to a duration referred to
as DL buffering duration.
2 . A method according to claim 1, comprising:
- a serving MME or a serving SGSN sending said request to said SGW,
such as in a Downlink Data Notification Acknowledge message.
3 . A method according to claim 1 or 2 , wherein:
- said request includes one or more of: an indication that said UE is
transiently not reachable, said DL buffering duration, a limit to the number of
buffered DL packets for the UE or per Packet Data Network PDN connection for the
UE.
4 . A method according to any of claims 1 to 3 , wherein:
- said buffering is controlled via user's subscription data stored in a Home
Subscriber Server HSS or via the serving MME or SGSN's operator's policy
configured in said serving MME or SGSN.
5 . A method according to any of claims 1 to 4 , comprising:
- upon TAU, respectively RAU, requiring a change of Serving Gateway
SGW, from an old SGW to a new SGW, allowing said one or more DL packets
buffered in the old SGW to be forwarded to the new SGW.
6 . A method according to any of claims 1 to 5 ,comprising:
- upon TAU, respectively RAU, requiring a change of Serving Gateway
SGW, from an old SGW to a new SGW, a serving MME, respectively SGSN,
requesting the new SGW, such as in a Create Session Request message, to
provide addressing information for forwarding of said one or more buffered DL
packets from said old SGW to said new SGW.
7 . A method according to any of claims 1 to 6 , comprising:
- upon TAU, respectively RAU, requiring a change of Serving Gateway
SGW, from an old SGW to a new SGW, the new SGW providing to a serving MME,
respectively SGSN, such as in a Create Session Response message, addressing
information for forwarding of said one or more buffered DL packets from said old
SGW to said new SGW.
8 . A method according to any of claims 1 to 7 , comprising:
- upon TAU, respectively RAU, requiring a change of Serving Gateway
SGW, from an old SGW to a new SGW, a serving MME, respectively SGSN,
providing to the old SGW, such as in a Delete Session Request message,
addressing information for forwarding of said one or more buffered DL packets from
said old SGW to said new SGW.
9 . A method according to any of claims 1 to 8 , comprising:
- upon TAU, respectively RAU, requiring a change of Serving Gateway
SGW , from an old SGW to a new SGW, the old SGW forwarding said one or more
buffered DL packets to the new SGW, and once done, sending one or more GTP U
End Markers Packets.
10. A method according to any of claims 1 to 9 , comprising:
- upon TAU, respectively RAU, requiring a change of Serving Gateway
SGW from an old SGW to a new SGW, and a change of serving node from an old
MME or old SGSN to a new MME, respectively a change of serving node from an
old MME or old SGSN to a new SGSN, the old MME or old SGSN sending to the
new MME, respectively to the new SGSN, such as in a Context Response message,
an indication that forwarding of said one or more buffered DL packets from said old
SGW to said new SGW is required.
11. A method according to any of claims 1 to 10 , comprising:
- upon TAU, respectively RAU, requiring a change of Serving Gateway
SGW from an old SGW to a new SGW, and a change of serving node from an old
MME or old SGSN to a new MME, respectively a change of serving node from an
old MME or old SGSN to a new SGSN, the new MME, respectively the new SGSN,
passing to the old MME or old SGSN, such as in a Context Acknowledge message,
addressing information for forwarding of said one or more buffered DL packets to
the new SGW.
12. A method according to any of claims 1 to 11, comprising:
- a serving MME or a serving SGSN deciding, based on configured
operator's policy or user's subscription data received from a Home Subscriber
Server HSS, whether or not to reject a Downlink Data Notification Request sent by a
Serving Gateway SGW for a UE using a power saving mechanism.
13. A method according to any of claims 1 to 12, comprising:
- in the case of a power saving mechanism corresponding to Extended
DRX, allowing said buffering until either the UE responds to a paging request, or
said DL buffering duration covering one or more DRX periods elapses, whichever
occurs first.
14. A method according to any of claims 1 to 13, comprising:
- in the case of a power saving mechanism corresponding to Power Saving
Mode PSM, allowing said buffering until either the UE triggers any uplink signalling,
or said DL buffering duration covering the UE's periodic TAU or RAU timer optionally
reduced by the time elapsed since the last UE signalling procedure, whichever
occurs first.
15. A method for support of Mobile Terminated SMS for a User Equipment
UE in idle mode using extended DRX, said method comprising:
- upon receipt of said Mobile Terminated SMS, a Mobility management
Entity MME or a Serving GPRS Support Node SGSN serving said UE immediately
reporting towards a Short Message Service Centre SMSC that the UE is not
reachable, and paging the UE,
- upon receipt of a paging response from the UE, the MME or the SGSN
alerting the SMSC via the HSS to trigger the SMSC to re-send the SMS.
16. A method for support of Mobile Terminated Location Request towards a
User Equipment UE using a power saving mechanism whereby the UE is transiently
not reachable, said method comprising:
- upon receipt of a network initiated location request from a Gateway Mobile
Location Centre GMLC, a Mobility management Entity MME or a Serving GPRS
Support Node SGSN, serving said UE immediately returning an answer towards the
GMLC containing a last known location for the UE, with an indication that the UE is
transiently not reachable, and paging the UE if the UE is using extended DRX,
- upon receipt of a paging response from the UE or upon the next signalling
activity for the UE, the MME or the SGSN sending towards the GMLC a Subscriber
Location Report.
17. An entity configured to perform at least one step of a method according
to any of claims 1 to 16, related to said network entity.