U.S. patent application number 13/829642 was filed with the patent office on 2013-11-14 for methods and apparatus for handling mtc long drx cycle/sleep lengths.
This patent application is currently assigned to INTERDIGITAL PATENT HOLDINGS, INC.. The applicant listed for this patent is INTERDIGITAL PATENT HOLDINGS, INC.. Invention is credited to Samian J. Kaur, Kai Liu, Ulises Olvera-Hernandez, Ghyslain Pelletier, Marian Rudolf, Michael F. Starsinic, Guanzhou Wang, Peter S. Wang.
Application Number | 20130301501 13/829642 |
Document ID | / |
Family ID | 48045734 |
Filed Date | 2013-11-14 |
United States Patent
Application |
20130301501 |
Kind Code |
A1 |
Olvera-Hernandez; Ulises ;
et al. |
November 14, 2013 |
METHODS AND APPARATUS FOR HANDLING MTC LONG DRX CYCLE/SLEEP
LENGTHS
Abstract
Current wireless networks do not allow machine type
communication (MTC) devices to have long discontinuous reception
(DRX) cycles or sleep lengths. A long DRX cycle may allow MTC
systems and devices to operate with much longer DRX/Sleep
cycles/periods. This may facilitate the MTC operations for
infrequent system access or infrequent system reaching (e.g. paged
once in a week) with no or low mobility and may allow MTC devices
to sleep for a long time with low power consumption.
Inventors: |
Olvera-Hernandez; Ulises;
(Kirkland, CA) ; Pelletier; Ghyslain; (Laval,
CA) ; Wang; Peter S.; (E. Setauket, NY) ; Liu;
Kai; (S. Huntington, NY) ; Wang; Guanzhou;
(Longueuil, CA) ; Rudolf; Marian; (Montreal,
CA) ; Kaur; Samian J.; (Plymouth Meeting, PA)
; Starsinic; Michael F.; (Newtown, PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
INTERDIGITAL PATENT HOLDINGS, INC. |
Wilmington |
DE |
US |
|
|
Assignee: |
INTERDIGITAL PATENT HOLDINGS,
INC.
Wilmington
DE
|
Family ID: |
48045734 |
Appl. No.: |
13/829642 |
Filed: |
March 14, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61644922 |
May 9, 2012 |
|
|
|
61653706 |
May 31, 2012 |
|
|
|
Current U.S.
Class: |
370/311 |
Current CPC
Class: |
H04W 76/28 20180201;
H04W 52/0216 20130101; H04W 4/70 20180201; Y02D 30/70 20200801 |
Class at
Publication: |
370/311 |
International
Class: |
H04W 76/04 20060101
H04W076/04 |
Claims
1. A WTRU, the WTRU comprising: a processor, the processor being
configured to: determine a cycle base unit type and a length of a
long discontinuous reception (DRX) cycle; generate a number of base
units of the cycle base unit type using the length of the long DRX
cycle; and generate the long DRX cycle from the number of base
units.
2. The WTRU of claim 1, wherein the cycle base unit type is an
extended subframe number (SFN) cycle type.
3. The WTRU of claim 2, wherein the processor is configured to
generate the number of base units of the cycle base unit type using
the length of the long DRX cycle by: determining n number of SFN
cycles to be used for an extended SFN cycle type base unit; and
generating a number of extended SFN cycles needed to make up the
length of the long DRX cycle, wherein each extended SFN cycle in
the number of extended SFN cycles comprises n number of SFN
cycles.
4. The WTRU of claim 3, wherein the processor is configured to
generate the long DRX cycle from the number of base units by
generating the long DRX cycle from the number of extended SFN
cycles.
5. The WTRU of claim 1, wherein the cycle base unit type is a time
unit type.
6. The WTRU of claim 5, wherein the processor is configured to
generate the number of base units of the cycle base unit type using
the length of the long DRX cycle by: determining a length of time
for the time unit type; determining a number of time units needed
to make up the length of the long DRX cycle; generating the number
of time units, wherein each time unit in the number of time units
comprises the length of time for the time unit type.
7. A wireless transmit/receive unit (WTRU) for determining when to
receive a signal, the WTRU comprising: a processor, the processor
being configured to: determine a system frame number cycle number
(SCN) within a total DRX period; determine a long DRX cycle length;
and generate an offset SCN using the SCN and the long DRX cycle
length.
8. The WTRU of claim 7, wherein the processor is further configured
to determine a page timing using the offset SCN.
9. The WTRU of claim 8, wherein the processor is further configured
to receive a paging signal from a network using the page
timing.
10. The WTRU of claim 7, wherein the processor is further
configured to: determine a number of short DRX cycles to be used to
receive a signal; and schedule a long DRX cycle using the offset
SCN and the long DRX cycle length.
11. The WTRU of claim 10, wherein the processor is further
configured to schedule the number of short DRX cycles within the
long DRX cycle using the short DRX cycle length.
12. The WTRU of claim 10, wherein the processor is further
configured to schedule the number of short DRX cycles before the
long DRX cycle using the short DRX cycle length.
13. The WTRU of claim 10, wherein the processor is further
configured to schedule the number of short DRX cycles after the
long DRX cycle using the short DRX cycle length.
14. The WTRU of claim 7, wherein the processor is further
configured to: determine a number of short DRX cycles to be used to
receive a signal; schedule a first long DRX cycle and a second long
DRX cycle using the offset SCN and the long DRX cycle length; and
schedule the number of short DRX cycles between the first long DRX
cycle and the second long DRX cycle.
15. A wireless transmit/receive unit (WTRU) for minimizing clock
drift impact, the WTRU comprising: a processor, the processor
configured to: determine a long sleep length, a clock drift rate
for a WTRU, and a wake-up time; and generate an adjustment window
using the long sleep length, the clock drift rate, and the wake-up
time.
16. The WTRU of claim 15, wherein the processor is further
configured to receive a signal from a network using the adjustment
window.
17. The WTRU of claim 15, wherein the processor is configured to
generate the adjustment window using the long sleep length, the
clock drift rate, and the wake-up time by: determining the
adjustment window using the long sleep length; scheduling the
adjustment window using the wake-up time; adjusting the adjustment
window using the clock drift rate such that a signal may be
received from a network during the adjustment window.
18. The WTRU of claim 15, wherein the processor is further
configured to determine a clock drift direction.
19. The WTRU of claim 18, wherein the processor is configured to
generate the adjustment window using the long sleep length, the
clock drift rate, and the wake-up time by: determining the
adjustment window using the long sleep length; scheduling the
adjustment window using the wake-up time; decreasing a length of
the adjustment window using the clock drift rate when the clock
drift direction indicates that a clock is drifting towards longer
time.
20. The WTRU of claim 18, wherein the processor is configured to
generate the adjustment window using the long sleep length, the
clock drift rate, and the wake-up time by: determining the
adjustment window using the long sleep length; scheduling the
adjustment window using the wake-up time; increasing a length of
the adjustment window using the clock drift rate when the clock
drift direction indicates that a clock is drifting towards shorter
time.
21. A WTRU comprising: a processor, the processor configured to:
receive a first system frame number (SFN) cycle order number from a
network; determine a second SFN cycle order number; and calculate a
drift range using the first SFN cycle order number and the second
SFN cycle order number.
22. The WTRU of claim 21, wherein the processor is configured to
receive the first SNF cycle order number from the network via a
system information.
23. The WTRU of claim 21, wherein the processor is further
configured to align a local SFN cycle number with the first SFN
cycle order number when the drift range indicates that first SFN
cycle order number and the second SFN cycle order number are not
aligned.
24. The WTRU of claim 23, wherein the processor is further
configured to determine a time to receive a signal from the network
using the aligned SFN cycle number.
25. The WTRU of claim 21, wherein the processor is further
configured to receive a signal from the network in a next SFN cycle
when the drift range indicates the network is scheduled to transmit
the signal in the next SFN cycle.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Patent Application No. 61/644,922, filed May 9, 2012; and U.S.
Provisional Patent Application No. 61/653,706, filed on May 31,
2012; the contents of which are hereby incorporated by reference
herein.
BACKGROUND
[0002] Machine type communication (MTC) devices may not need to
frequently connect to a network to deliver or receive data.
Additionally, a network may schedule a radio resource for a MTC
device on a small number of occasions. Accordingly, MTC devices may
not need to monitor a network for a signal or page as often as
non-MTC devices. However, current wireless networks do not allow
for long discontinuous reception (DRX) cycles or sleep lengths.
SUMMARY
[0003] Disclosed herein are methods and apparatus to enable
wireless networks to provide a long discontinuous reception (DRX)
cycle or sleep length. The embodiments may allow systems and MTC
devices, such as a wireless transmit/receive unit (WTRU), to
operate with long DRX cycles, sleep cycles, and/or periods. The
embodiments may provide and/or enable MTC operations to permit
infrequent system access or system reaching. The embodiments may
allow MTC devices to sleep for a long period with low power
consumption. The embodiments may also allow wireless networks to
use an eNodeB (eNB) to perform energy saving algorithms.
[0004] A WTRU may be provided that may include a processor
configured to perform a number of actions. For example, the
processor may be configured to determine a cycle base unit type and
a length of a discontinuous reception (DRX) cycle. A number of base
units of the cycle base unit type may be generated using the length
of the long DRX cycle. The long DRX cycle may be generated from the
number of base units.
[0005] A WTRU for determining when to receive a signal may be
provided. The WTRU may include a processor that may be configured
to perform a number of actions. For example, the processor may be
configured to determine a system frame number cycle number (SCN)
within a total DRX period. A long DRX cycle length may be
determined. An offset SCN may be generated using the SCN and the
long DRX cycle length.
[0006] A WTRU for minimizing clock drift impact may be provided.
The WTRU may include a processor that may be configured to perform
a number of actions. For example, the processor may be configured
to determine a long sleep length, a clock drift rate for a WTRU,
and a wake-up time. An adjustment window may be generated using the
long sleep length, the clock drift rate, and the wake up time.
[0007] A WTRU may be provided that may include a processor
configured to perform a number of actions. For example, the
processor may be configured to receive a first system frame number
(SFN) cycle order number from a network. A second SFN cycle order
number may be determined A drift range may be calculated using the
first SFN cycle order number and the second SFN cycle order
number.
[0008] The Summary is provided to introduce a selection of concepts
in a simplified form that are further described below in the
Detailed Description. This Summary is not intended to identify key
features or essential features of the claimed subject matter, not
is it intended to be used to limit the scope of the claimed subject
matter. Furthermore, the claimed subject matter is not limited to
any limitations that solve any or all disadvantages noted in any
part of this disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] A more detailed understanding may be had from the following
description, given by way of example in conjunction with the
accompanying drawings.
[0010] FIG. 1A depicts a system diagram of an example
communications system in which one or more disclosed embodiments
may be implemented.
[0011] FIG. 1B depicts a system diagram of an example wireless
transmit/receive unit (WTRU) that may be used within the
communications system illustrated in FIG. 1A.
[0012] FIG. 1C depicts a system diagram of an example radio access
network and an example core network (CN) that may be used within
the communications system illustrated in FIG. 1A.
[0013] FIG. 1D depicts a system diagram of an example radio access
network and an example core network that may be used within the
communications system illustrated in FIG. 1A.
[0014] FIG. 1E depicts a system diagram of an example radio access
network and an example core network that may be used within the
communications system illustrated in FIG. 1A.
[0015] FIG. 2 depicts an example of a short discontinuous reception
cycle (DRX) cycle scheduled within a long DRX cycle.
[0016] FIG. 3 depicts an example of a short cycle being used in
between long DRX cycles.
[0017] FIG. 4 depicts an example method for DRX configuration that
may be initiated by a service capability server (SCS).
[0018] FIG. 5 depicts an example method for a DRX cycle
configuration that may be initiated by a radio access network
(RAN).
[0019] FIG. 6 depicts another example method for a DRX cycle
configuration that may be initiated by a RAN.
[0020] FIG. 7 depicts example network and WTRU procedures for busy
reaching and monitoring.
[0021] FIG. 8 depicts example SFN cycle order numbers 0 and 1.
[0022] FIG. 9 depicts example local SFN cycle order numbers 0, 1,
2, and 3.
[0023] FIG. 10 depicts an example WTRU clock realignment.
[0024] FIG. 11 depicts another example WTRU clock realignment.
DETAILED DESCRIPTION
[0025] A detailed description of illustrative embodiments will now
be described with reference to the various Figures. Although this
description provides a detailed example of possible
implementations, it should be noted that the details are intended
to be exemplary and in no way limit the scope of the
application.
[0026] Some mobile networks may be optimized for human-to-human
communications and may be less optimal for machine-to-machine (M2M)
communications. Support for machine-type communications (MTC) may
be used to accommodate the demand for machine type communications
in wireless networks, such as 3GPP LTE wireless networks.
[0027] Machine Type Communication (MTC) devices may include
wireless transmit/receive units, such as cell phones, metering
devices, or the like that may access the network less frequently
than devices used for human-to-human use. The MTC devices may be
wireless sensors or the like that may be deployed to remote areas
for monitoring tasks or other tasks, where there may be limited
access to power.
[0028] MTC devices may not request to be continually connected for
deliver or receive data. For example, a network may allocate radio
resources for an MTC device on a reduce number of occasions, which
may follow a pattern. MTC devices may not be requested listen to
network signaling or network paging for long periods. MTC devices
may monitor network signaling or paging less often than non-MTC
devices.
[0029] A network may have knowledge of the location of a MTC device
or may have knowledge of a geographic location where an MTC device
may be found. MTC devices may perform less mobility related tasks
(e.g. TAU) or cell measurements, or may not perform mobility
related tasks during a sleep/dormant period.
[0030] MTC devices deployed in a remote area or in an inconvenient
area may operate on battery power and may wish to save power. In
some cases, MTC battery life may be expected to last for an
extended amount of time, such as ten years.
[0031] For power saving purposes, a device may shut down for a long
period of time, which may be scheduled, and may not listen to a
network during this scheduled period of time. In some cases, the
MTC device may continue timing and timer maintenance procedures
during this period. After this period is over, the device may wake
up and may listen to signals, such as MTC downlink paging signals,
triggering signals, reaching signals, or the like. This may be
done, for example, to determine if the network wishes to
communicate with the device.
[0032] There may be a number of scenarios where a device may wake
up. For example, a device may wake up and may attempt a system
access to deliver user data content. As another example, a device
may wake up to read system information where the network may try to
deliver user data content.
[0033] As an example, a device may wake up and may attempt to
access a system to delivery data. This may occur, for example, when
a power meter wakes up a month at a time to report a power meter
reading. As another example, a device may wake up to read system
information in case the network may try to deliver data. This may
occur, for example, when a device wakes up once a week to determine
if the network has an administrative request or task for it, such
as an instruction to cut off electric supply for a tenant who may
be moving out of an apartment.
[0034] A prolonged sleeping period may be referred to as a long DRX
cycle or an extended DRX cycle. A long DRX cycle may be a cycle
length of a month, a week, a day, or the like. Provisioning of a
long or DRX cycle may place a MTC device into an offline shutdown
state where the device may not measure the serving cell frequently
to ensure coverage for a long period. This may provide
opportunities for base stations to perform energy saving tasks,
such as planned power downs.
[0035] Although devices may simply shut off and power back on as
requested, this uncoordinated behavior may lead to having a large
amount of devices that may waking up around the same time. This may
result in congestion surges. An uncoordinated scheme may rely on a
device pulling mechanism where the device may check at regular
intervals whether there may be data waiting instead of having the
network push data upon arrival based on paging slots.
[0036] A DRX-like mechanism may be provided for devices that may
sleep longer than the current LTE System Frame Number (SFN) cycle
may allow. This may provide a device-network synchronization
mechanism that may allow a manageable distribution of devices
waking up to access the system. This may also enable the network to
deliver user data to devices that may have slept for long periods
of time without relying on data pulling mechanisms.
[0037] A Long-DRX length unit and/or a Total-DRX-Definition-Period
may be a time, a SFN cycle, a combination thereof, or the like, and
may be used to allow a device to sleep in days/weeks/months, etc.
Scheduling formulas may be provided for configuring WTRUs for
long-DRX in a Total-DRX-Definition-Period. Methods may be provided
to arrange short DRX within a long-DRX period. An adjustment-window
length may be provided and may be a function of the long DRX cycle
length and the clock drift rate. Procedures may be provided to
schedule an adjustment window for a network and/or a WTRU that may
assure that the WTRU may not miss network paging/signaling when the
WTRU wakes up with misaligned timing that may be caused by, for
example, drift. Network assisted WTRU resynchronization and WTRU
autonomous adjustment may be provided. Procedures for coordination
of long DRX cycles between a RAN, a WTRU, and Service Capability
Server (SCS) may be provided.
[0038] To provide device-network synchronization, a DRX mechanism
may be used for devices that may use a cycle that may be longer
than the current LTE System Frame Number cycle. This may allow a
manageable distribution of devices to wake up and access a system.
Additionally, this may ensure that the network may deliver data to
devices that may have slept for long periods of time without
relying on data pulling mechanisms.
[0039] In current LTE, a default paging cycle length for a WTRU is,
in general, configured to be between 32 to 256 LTE frames (i.e. a
device sleeps for about 32 to 256 frames or 0.32 to 2.56 seconds,
then wakes up) within a complete SFN cycle (1024 LTE frames).
[0040] The current complete LTE SFN cycle is 1024 frames=10.24
seconds or 4096 UMTS frames=40.96 seconds. This time period
definition may not be long enough to accommodate longer DRX
requirements for MTC devices that may request long sleeping
periods, such as days, hours, or the like. Thus, the devices may
request longer periods than what is offered by the current LTE or
UMTS complete SFN cycle.
[0041] If a MTC device, such as a WTRU, were to go into a long
sleep for a period long than a SFN cycle, synchronization issues
may occur and the local clock may not be adjusted by the network
clock. Additionally, the WTRU may not be able to receive network
paging messages that were previously scheduled. For example, a WTRU
may be in a power saving mode for a long sleep that may last days
or weeks. During this period the WTRU may not have contact with the
network. A clock used by the WTRU to count timing for a scheduled
wake-up may drift. The longer the long-deep-sleep, the more the
timing may drift when the device wakes-up. When the WTRU wakes up,
the monitoring clock may have drifted. If local clock has drifted
beyond a limit, the WTRU may not be able to synchronize and the
WTRU may not be able to receive network signaling or paging around
the scheduled time.
[0042] The current LTE SFN cycle may not evenly distribute delay
tolerant MTC device traffic and network access during low system
load periods with a long DRX cycle. Additionally, the current LTE
SNF cycle may not allow for different DRX or sleep time length
units, such as a calendar time unit, that may be used to enable the
configuration of MTC DRX or sleep period in order to wake up at the
service desired time or moment.
[0043] Extended DRX cycles may allow for closer coordination
between the RAN and the Service Capability Server (SCS) and/or MTC
interworking function (IWF).
[0044] Long DRX cycles may be used to limit when other entities may
be able to contact the device as the device may be contacted when
the device may be available. For example, the SCS may contact the
device over the user plane or via a trigger. Since SCS operation
may be impacted by the DRX cycle of its registered devices, the SCS
may be part of the DRX cycle negotiation or the SCS may be made
aware of the DRX cycle of its registered devices.
[0045] When the SCS may not be aware of the DRX cycles or of its
connected devices, then the SCS may attempt to contact the device
over the SGi/Gi user plane or via T.sub.sp trigger requests while
the device may be sleeping. These contact attempts may cause
unwanted signaling between the core network (CN) and the SCS.
Mechanisms may be provided to allow the RAN to inform the SCS of
the MTC device's DRX cycle.
[0046] The core network may reject any communication attempt
towards a device that may be is in a long DRX cycle. Additional
measures may be taken to ensure that the SCS and its associated
network applications may not attempt to continuously reach sleeping
devices.
[0047] The core network may not know how long devices may be
allowed to sleep without breaking application level functionality.
The SCS may know this information or may be able to learn it when
the MTC device registers with the SCS. Mechanisms may be provided
to allow the SCS to inform the RAN of the DRX requests of an MTC
device, such as how long the device may sleep without breaking the
application requirements.
[0048] There may be some cases where the device may simply inform
the RAN of its DRX requests. However, it may be more efficient if
the SCS coordinated when it may poll the meters, how often they may
be polled, and when they may be available for SW upgrades.
[0049] Embodiments described herein may provide units and
mechanisms for long-drx time scenarios that may allow and support
the LTE time unit for time periods longer than a complete SFN
cycle.
[0050] Procedures and messages may be provided to allow the SCS to
coordinate the allowable DRX cycle lengths with the RAN.
[0051] Embodiments disclosed herein may provide methods to mitigate
synchronization issues that may occur when the local WTRU clock
drifts beyond a recovering period. These methods may include
mechanisms that may allow the reception of paging messages within a
time window, which may be affected by factors such as the long
sleep time, WTRU speed, WTRU capabilities, or the like. For
example, given a clock drift rate, the length of the
adjustment-window may be a function of the long-deep-sleep length
such that the longer the long-deep-sleep length, the greater the
adjustment-widow length/size. Embodiments may allow for a
relationship between an adjustment-window and a
long-deep-sleep-length. The embodiments may also provide actions
that may be taken by a WTRU, a network (such as eNB and MME), or
both the WTRU and network before or during the adjustment-window
period.
[0052] As used herein, the term extended DRX cycle, the term long
DRX cycle, and the term long sleep cycle/period may be used
interchangeably. The term adjustment-window and the term
receive-window may also be used interchangeably.
[0053] Although the embodiments may be described in terms of an LTE
network, the embodiments may also apply to other radio access
technologies, networks, devices, and periodic operations, such as
network broadcast/multicast and WTRU receptions.
[0054] The long DRX cycle and its operation configuration may be
configured for WTRUs that may request a long sleep. As used herein,
a serving node and may refer to mobile switching center (MSC), a
serving general packet radio service (GPRS) support node (SGSN), or
mobility manager gateway (MME).
[0055] FIG. 1A is a diagram of an example communications system 100
in which one or more disclosed embodiments may be implemented. The
communications system 100 may be a multiple access system that
provides content, such as voice, data, video, messaging, broadcast,
etc., to multiple wireless users. The communications system 100 may
enable multiple wireless users to access such content through the
sharing of system resources, including wireless bandwidth. For
example, the communications systems 100 may employ one or more
channel access methods, such as code division multiple access
(CDMA), time division multiple access (TDMA), frequency division
multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier
FDMA (SC-FDMA), and the like.
[0056] As shown in FIG. 1A, the communications system 100 may
include wireless transmit/receive units (WTRUs) 102a, 102b, 102c,
and/or 102d (which generally or collectively may be referred to as
WTRU 102), a radio access network (RAN) 103/104/105, a core network
106/107/109, a public switched telephone network (PSTN) 108, the
Internet 110, and other networks 112, though it will be appreciated
that the disclosed embodiments contemplate any number of WTRUs,
base stations, networks, and/or network elements. Each of the WTRUs
102a, 102b, 102c, 102d may be any type of device configured to
operate and/or communicate in a wireless environment. By way of
example, the WTRUs 102a, 102b, 102c, 102d may be configured to
transmit and/or receive wireless signals and may include user
equipment (UE), a mobile station, a fixed or mobile subscriber
unit, a pager, a cellular telephone, a personal digital assistant
(PDA), a smartphone, a laptop, a netbook, a personal computer, a
wireless sensor, consumer electronics, and the like.
[0057] The communications systems 100 may also include a base
station 114a and a base station 114b. Each of the base stations
114a, 114b may be any type of device configured to wirelessly
interface with at least one of the WTRUs 102a, 102b, 102c, 102d to
facilitate access to one or more communication networks, such as
the core network 106/107/109, the Internet 110, and/or the networks
112. By way of example, the base stations 114a, 114b may be a base
transceiver station (BTS), a Node-B, an eNode B, a Home Node B, a
Home eNode B, a site controller, an access point (AP), a wireless
router, and the like. While the base stations 114a, 114b are each
depicted as a single element, it will be appreciated that the base
stations 114a, 114b may include any number of interconnected base
stations and/or network elements.
[0058] The base station 114a may be part of the RAN 103/104/105,
which may also include other base stations and/or network elements
(not shown), such as a base station controller (BSC), a radio
network controller (RNC), relay nodes, etc. The base station 114a
and/or the base station 114b may be configured to transmit and/or
receive wireless signals within a particular geographic region,
which may be referred to as a cell (not shown). The cell may
further be divided into cell sectors. For example, the cell
associated with the base station 114a may be divided into three
sectors. Thus, in one embodiment, the base station 114a may include
three transceivers, i.e., one for each sector of the cell. In
another embodiment, the base station 114a may employ multiple-input
multiple output (MIMO) technology and, therefore, may utilize
multiple transceivers for each sector of the cell.
[0059] The base stations 114a, 114b may communicate with one or
more of the WTRUs 102a, 102b, 102c, 102d over an air interface
115/116/117, which may be any suitable wireless communication link
(e.g., radio frequency (RF), microwave, infrared (IR), ultraviolet
(UV), visible light, etc.). The air interface 115/116/117 may be
established using any suitable radio access technology (RAT).
[0060] More specifically, as noted above, the communications system
100 may be a multiple access system and may employ one or more
channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA,
and the like. For example, the base station 114a in the RAN
103/104/105 and the WTRUs 102a, 102b, 102c may implement a radio
technology such as Universal Mobile Telecommunications System
(UMTS) Terrestrial Radio Access (UTRA), which may establish the air
interface 115/116/117 using wideband CDMA (WCDMA). WCDMA may
include communication protocols such as High-Speed Packet Access
(HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-Speed
Downlink Packet Access (HSDPA) and/or High-Speed Uplink Packet
Access (HSUPA).
[0061] In another embodiment, the base station 114a and the WTRUs
102a, 102b, 102c may implement a radio technology such as Evolved
UMTS Terrestrial Radio Access (E-UTRA), which may establish the air
interface 115/116/117 using Long Term Evolution (LTE) and/or
LTE-Advanced (LTE-A).
[0062] In other embodiments, the base station 114a and the WTRUs
102a, 102b, 102c may implement radio technologies such as IEEE
802.16 (i.e., Worldwide Interoperability for Microwave Access
(WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard
2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856
(IS-856), Global System for Mobile communications (GSM), Enhanced
Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and the
like.
[0063] The base station 114b in FIG. 1A may be a wireless router,
Home Node B, Home eNode B, or access point, for example, and may
utilize any suitable RAT for facilitating wireless connectivity in
a localized area, such as a place of business, a home, a vehicle, a
campus, and the like. In one embodiment, the base station 114b and
the WTRUs 102c, 102d may implement a radio technology such as IEEE
802.11 to establish a wireless local area network (WLAN). In
another embodiment, the base station 114b and the WTRUs 102c, 102d
may implement a radio technology such as IEEE 802.15 to establish a
wireless personal area network (WPAN). In yet another embodiment,
the base station 114b and the WTRUs 102c, 102d may utilize a
cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, etc.)
to establish a picocell or femtocell. As shown in FIG. 1A, the base
station 114b may have a direct connection to the Internet 110.
Thus, the base station 114b may not be requested to access the
Internet 110 via the core network 106/107/109.
[0064] The RAN 103/104/105 may be in communication with the core
network 106/107/109, which may be any type of network configured to
provide voice, data, applications, and/or voice over internet
protocol (VoIP) services to one or more of the WTRUs 102a, 102b,
102c, 102d. For example, the core network 106/107/109 may provide
call control, billing services, mobile location-based services,
pre-paid calling, Internet connectivity, video distribution, etc.,
and/or perform high-level security functions, such as user
authentication. Although not shown in FIG. 1A, it will be
appreciated that the RAN 103/104/105 and/or the core network
106/107/109 may be in direct or indirect communication with other
RANs that employ the same RAT as the RAN 103/104/105 or a different
RAT. For example, in addition to being connected to the RAN
103/104/105, which may be utilizing an E-UTRA radio technology, the
core network 106/107/109 may also be in communication with another
RAN (not shown) employing a GSM radio technology.
[0065] The core network 106/107/109 may also serve as a gateway for
the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the
Internet 110, and/or other networks 112. The PSTN 108 may include
circuit-switched telephone networks that provide plain old
telephone service (POTS). The Internet 110 may include a global
system of interconnected computer networks and devices that use
common communication protocols, such as the transmission control
protocol (TCP), user datagram protocol (UDP) and the internet
protocol (IP) in the TCP/IP internet protocol suite. The networks
112 may include wired or wireless communications networks owned
and/or operated by other service providers. For example, the
networks 112 may include another core network connected to one or
more RANs, which may employ the same RAT as the RAN 103/104/105 or
a different RAT.
[0066] Some or all of the WTRUs 102a, 102b, 102c, 102d in the
communications system 100 may include multi-mode capabilities,
i.e., the WTRUs 102a, 102b, 102c, 102d may include multiple
transceivers for communicating with different wireless networks
over different wireless links. For example, the WTRU 102c shown in
FIG. 1A may be configured to communicate with the base station
114a, which may employ a cellular-based radio technology, and with
the base station 114b, which may employ an IEEE 802 radio
technology.
[0067] FIG. 1B is a system diagram of an example WTRU 102. As shown
in FIG. 1B, the WTRU 102 may include a processor 118, a transceiver
120, a transmit/receive element 122, a speaker/microphone 124, a
keypad 126, a display/touchpad 128, non-removable memory 130,
removable memory 132, a power source 134, a global positioning
system (GPS) chipset 136, and other peripherals 138. It will be
appreciated that the WTRU 102 may include any sub-combination of
the foregoing elements while remaining consistent with an
embodiment. Also, embodiments contemplate that the base stations
114a and 114b, and/or the nodes that base stations 114a and 114b
may represent, such as but not limited to transceiver station
(BTS), a Node-B, a site controller, an access point (AP), a home
node-B, an evolved home node-B (eNodeB), a home evolved node-B
(HeNB), a home evolved node-B gateway, and proxy nodes, among
others, may include some or all of the elements depicted in FIG. 1B
and described herein.
[0068] The processor 118 may be a general purpose processor, a
special purpose processor, a conventional processor, a digital
signal processor (DSP), a plurality of microprocessors, one or more
microprocessors in association with a DSP core, a controller, a
microcontroller, Application Specific Integrated Circuits (ASICs),
Field Programmable Gate Array (FPGAs) circuits, any other type of
integrated circuit (IC), a state machine, and the like. The
processor 118 may perform signal coding, data processing, power
control, input/output processing, and/or any other functionality
that enables the WTRU 102 to operate in a wireless environment. The
processor 118 may be coupled to the transceiver 120, which may be
coupled to the transmit/receive element 122. While FIG. 1B depicts
the processor 118 and the transceiver 120 as separate components,
it will be appreciated that the processor 118 and the transceiver
120 may be integrated together in an electronic package or
chip.
[0069] The transmit/receive element 122 may be configured to
transmit signals to, or receive signals from, a base station (e.g.,
the base station 114a) over the air interface 115/116/117. For
example, in one embodiment, the transmit/receive element 122 may be
an antenna configured to transmit and/or receive RF signals. In
another embodiment, the transmit/receive element 122 may be an
emitter/detector configured to transmit and/or receive IR, UV, or
visible light signals, for example. In yet another embodiment, the
transmit/receive element 122 may be configured to transmit and
receive both RF and light signals. It will be appreciated that the
transmit/receive element 122 may be configured to transmit and/or
receive any combination of wireless signals.
[0070] In addition, although the transmit/receive element 122 is
depicted in FIG. 1B as a single element, the WTRU 102 may include
any number of transmit/receive elements 122. More specifically, the
WTRU 102 may employ MIMO technology. Thus, in one embodiment, the
WTRU 102 may include two or more transmit/receive elements 122
(e.g., multiple antennas) for transmitting and receiving wireless
signals over the air interface 115/116/117.
[0071] The transceiver 120 may be configured to modulate the
signals that are to be transmitted by the transmit/receive element
122 and to demodulate the signals that are received by the
transmit/receive element 122. As noted above, the WTRU 102 may have
multi-mode capabilities. Thus, the transceiver 120 may include
multiple transceivers for enabling the WTRU 102 to communicate via
multiple RATs, such as UTRA and IEEE 802.11, for example.
[0072] The processor 118 of the WTRU 102 may be coupled to, and may
receive user input data from, the speaker/microphone 124, the
keypad 126, and/or the display/touchpad 128 (e.g., a liquid crystal
display (LCD) display unit or organic light-emitting diode (OLED)
display unit). The processor 118 may also output user data to the
speaker/microphone 124, the keypad 126, and/or the display/touchpad
128. In addition, the processor 118 may access information from,
and store data in, any type of suitable memory, such as the
non-removable memory 130 and/or the removable memory 132. The
non-removable memory 130 may include random-access memory (RAM),
read-only memory (ROM), a hard disk, or any other type of memory
storage device. The removable memory 132 may include a subscriber
identity module (SIM) card, a memory stick, a secure digital (SD)
memory card, and the like. In other embodiments, the processor 118
may access information from, and store data in, memory that is not
physically located on the WTRU 102, such as on a server or a home
computer (not shown).
[0073] The processor 118 may receive power from the power source
134, and may be configured to distribute and/or control the power
to the other components in the WTRU 102. The power source 134 may
be any suitable device for powering the WTRU 102. For example, the
power source 134 may include one or more dry cell batteries (e.g.,
nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride
(NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, and
the like.
[0074] The processor 118 may also be coupled to the GPS chipset
136, which may be configured to provide location information (e.g.,
longitude and latitude) regarding the current location of the WTRU
102. In addition to, or in lieu of, the information from the GPS
chipset 136, the WTRU 102 may receive location information over the
air interface 115/116/117 from a base station (e.g., base stations
114a, 114b) and/or determine its location based on the timing of
the signals being received from two or more nearby base stations.
It will be appreciated that the WTRU 102 may acquire location
information by way of any suitable location-determination method
while remaining consistent with an embodiment.
[0075] The processor 118 may further be coupled to other
peripherals 138, which may include one or more software and/or
hardware modules that provide additional features, functionality
and/or wired or wireless connectivity. For example, the peripherals
138 may include an accelerometer, an e-compass, a satellite
transceiver, a digital camera (for photographs or video), a
universal serial bus (USB) port, a vibration device, a television
transceiver, a hands free headset, a Bluetooth.RTM. module, a
frequency modulated (FM) radio unit, a digital music player, a
media player, a video game player module, an Internet browser, and
the like.
[0076] FIG. 1C is a system diagram of the RAN 103 and the core
network 106 according to an embodiment. As noted above, the RAN 103
may employ a UTRA radio technology to communicate with the WTRUs
102a, 102b, 102c over the air interface 115. The RAN 103 may also
be in communication with the core network 106. As shown in FIG. 1C,
the RAN 103 may include Node-Bs 140a, 140b, 140c, which may each
include one or more transceivers for communicating with the WTRUs
102a, 102b, 102c over the air interface 115. The Node-Bs 140a,
140b, 140c may each be associated with a particular cell (not
shown) within the RAN 103. The RAN 103 may also include RNCs 142a,
142b. It will be appreciated that the RAN 103 may include any
number of Node-Bs and RNCs while remaining consistent with an
embodiment.
[0077] As shown in FIG. 1C, the Node-Bs 140a, 140b may be in
communication with the RNC 142a. Additionally, the Node-B 140c may
be in communication with the RNC 142b. The Node-Bs 140a, 140b, 140c
may communicate with the respective RNCs 142a, 142b via an Iub
interface. The RNCs 142a, 142b may be in communication with one
another via an Iur interface. Each of the RNCs 142a, 142b may be
configured to control the respective Node-Bs 140a, 140b, 140c to
which it is connected. In addition, each of the RNCs 142a, 142b may
be configured to carry out or support other functionality, such as
outer loop power control, load control, admission control, packet
scheduling, handover control, macrodiversity, security functions,
data encryption, and the like.
[0078] The core network 106 shown in FIG. 1C may include a media
gateway (MGW) 144, a mobile switching center (MSC) 146, a serving
GPRS support node (SGSN) 148, and/or a gateway GPRS support node
(GGSN) 150. While each of the foregoing elements are depicted as
part of the core network 106, it will be appreciated that any one
of these elements may be owned and/or operated by an entity other
than the core network operator.
[0079] The RNC 142a in the RAN 103 may be connected to the MSC 146
in the core network 106 via an IuCS interface. The MSC 146 may be
connected to the MGW 144. The MSC 146 and the MGW 144 may provide
the WTRUs 102a, 102b, 102c with access to circuit-switched
networks, such as the PSTN 108, to facilitate communications
between the WTRUs 102a, 102b, 102c and traditional land-line
communications devices.
[0080] The RNC 142a in the RAN 103 may also be connected to the
SGSN 148 in the core network 106 via an IuPS interface. The SGSN
148 may be connected to the GGSN 150. The SGSN 148 and the GGSN 150
may provide the WTRUs 102a, 102b, 102c with access to
packet-switched networks, such as the Internet 110, to facilitate
communications between and the WTRUs 102a, 102b, 102c and
IP-enabled devices.
[0081] As noted above, the core network 106 may also be connected
to the networks 112, which may include other wired or wireless
networks that are owned and/or operated by other service
providers.
[0082] FIG. 1D is a system diagram of the RAN 104 and the core
network 107 according to an embodiment. As noted above, the RAN 104
may employ an E-UTRA radio technology to communicate with the WTRUs
102a, 102b, 102c over the air interface 116. The RAN 104 may also
be in communication with the core network 107.
[0083] The RAN 104 may include eNode-Bs 160a, 160b, 160c, though it
will be appreciated that the RAN 104 may include any number of
eNode-Bs while remaining consistent with an embodiment. The
eNode-Bs 160a, 160b, 160c may each include one or more transceivers
for communicating with the WTRUs 102a, 102b, 102c over the air
interface 116. In one embodiment, the eNode-Bs 160a, 160b, 160c may
implement MIMO technology. Thus, the eNode-B 160a, for example, may
use multiple antennas to transmit wireless signals to, and receive
wireless signals from, the WTRU 102a.
[0084] Each of the eNode-Bs 160a, 160b, 160c may be associated with
a particular cell (not shown) and may be configured to handle radio
resource management decisions, handover decisions, scheduling of
users in the uplink and/or downlink, and the like. As shown in FIG.
1D, the eNode-Bs 160a, 160b, 160c may communicate with one another
over an X2 interface.
[0085] The core network 107 shown in FIG. 1D may include a mobility
management gateway (MME) 162, a serving gateway 164, and a packet
data network (PDN) gateway 166. While each of the foregoing
elements are depicted as part of the core network 107, it will be
appreciated that any one of these elements may be owned and/or
operated by an entity other than the core network operator.
[0086] The MME 162 may be connected to each of the eNode-Bs 160a,
160b, 160c in the RAN 104 via an S1 interface and may serve as a
control node. For example, the MME 162 may be responsible for
authenticating users of the WTRUs 102a, 102b, 102c, bearer
activation/deactivation, selecting a particular serving gateway
during an initial attach of the WTRUs 102a, 102b, 102c, and the
like. The MME 162 may also provide a control plane function for
switching between the RAN 104 and other RANs (not shown) that
employ other radio technologies, such as GSM or WCDMA.
[0087] The serving gateway 164 may be connected to each of the
eNode-Bs 160a, 160b, 160c in the RAN 104 via the S1 interface. The
serving gateway 164 may generally route and forward user data
packets to/from the WTRUs 102a, 102b, 102c. The serving gateway 164
may also perform other functions, such as anchoring user planes
during inter-eNode B handovers, triggering paging when downlink
data is available for the WTRUs 102a, 102b, 102c, managing and
storing contexts of the WTRUs 102a, 102b, 102c, and the like.
[0088] The serving gateway 164 may also be connected to the PDN
gateway 166, which may provide the WTRUs 102a, 102b, 102c with
access to packet-switched networks, such as the Internet 110, to
facilitate communications between the WTRUs 102a, 102b, 102c and
IP-enabled devices.
[0089] The core network 107 may facilitate communications with
other networks. For example, the core network 107 may provide the
WTRUs 102a, 102b, 102c with access to circuit-switched networks,
such as the PSTN 108, to facilitate communications between the
WTRUs 102a, 102b, 102c and traditional land-line communications
devices. For example, the core network 107 may include, or may
communicate with, an IP gateway (e.g., an IP multimedia subsystem
(IMS) server) that serves as an interface between the core network
107 and the PSTN 108. In addition, the core network 107 may provide
the WTRUs 102a, 102b, 102c with access to the networks 112, which
may include other wired or wireless networks that are owned and/or
operated by other service providers.
[0090] FIG. 1E is a system diagram of the RAN 105 and the core
network 109 according to an embodiment. The RAN 105 may be an
access service network (ASN) that employs IEEE 802.16 radio
technology to communicate with the WTRUs 102a, 102b, 102c over the
air interface 117. As will be further discussed below, the
communication links between the different functional entities of
the WTRUs 102a, 102b, 102c, the RAN 105, and the core network 109
may be defined as reference points.
[0091] As shown in FIG. 1E, the RAN 105 may include base stations
180a, 180b, 180c, and an ASN gateway 182, though it will be
appreciated that the RAN 105 may include any number of base
stations and ASN gateways while remaining consistent with an
embodiment. The base stations 180a, 180b, 180c may each be
associated with a particular cell (not shown) in the RAN 105 and
may each include one or more transceivers for communicating with
the WTRUs 102a, 102b, 102c over the air interface 117. In one
embodiment, the base stations 180a, 180b, 180c may implement MIMO
technology. Thus, the base station 180a, for example, may use
multiple antennas to transmit wireless signals to, and receive
wireless signals from, the WTRU 102a. The base stations 180a, 180b,
180c may also provide mobility management functions, such as
handoff triggering, tunnel establishment, radio resource
management, traffic classification, quality of service (QoS) policy
enforcement, and the like. The ASN gateway 182 may serve as a
traffic aggregation point and may be responsible for paging,
caching of subscriber profiles, routing to the core network 109,
and the like.
[0092] The air interface 117 between the WTRUs 102a, 102b, 102c and
the RAN 105 may be defined as an R1 reference point that implements
the IEEE 802.16 specification. In addition, each of the WTRUs 102a,
102b, 102c may establish a logical interface (not shown) with the
core network 109. The logical interface between the WTRUs 102a,
102b, 102c and the core network 109 may be defined as an R2
reference point, which may be used for authentication,
authorization, IP host configuration management, and/or mobility
management.
[0093] The communication link between each of the base stations
180a, 180b, 180c may be defined as an R8 reference point that
includes protocols for facilitating WTRU handovers and the transfer
of data between base stations. The communication link between the
base stations 180a, 180b, 180c and the ASN gateway 182 may be
defined as an R6 reference point. The R6 reference point may
include protocols for facilitating mobility management based on
mobility events associated with each of the WTRUs 102a, 102b,
102c.
[0094] As shown in FIG. 1E, the RAN 105 may be connected to the
core network 109. The communication link between the RAN 105 and
the core network 109 may defined as an R3 reference point that
includes protocols for facilitating data transfer and mobility
management capabilities, for example. The core network 109 may
include a mobile IP home agent (MIP-HA) 184, an authentication,
authorization, accounting (AAA) server 186, and a gateway 188.
While each of the foregoing elements are depicted as part of the
core network 109, it will be appreciated that any one of these
elements may be owned and/or operated by an entity other than the
core network operator.
[0095] The MIP-HA may be responsible for IP address management, and
may enable the WTRUs 102a, 102b, 102c to roam between different
ASNs and/or different core networks. The MIP-HA 184 may provide the
WTRUs 102a, 102b, 102c with access to packet-switched networks,
such as the Internet 110, to facilitate communications between the
WTRUs 102a, 102b, 102c and IP-enabled devices. The AAA server 186
may be responsible for user authentication and for supporting user
services. The gateway 188 may facilitate interworking with other
networks. For example, the gateway 188 may provide the WTRUs 102a,
102b, 102c with access to circuit-switched networks, such as the
PSTN 108, to facilitate communications between the WTRUs 102a,
102b, 102c and traditional land-line communications devices. In
addition, the gateway 188 may provide the WTRUs 102a, 102b, 102c
with access to the networks 112, which may include other wired or
wireless networks that are owned and/or operated by other service
providers.
[0096] Although not shown in FIG. 1E, it will be appreciated that
the RAN 105 may be connected to other ASNs and the core network 109
may be connected to other core networks. The communication link
between the RAN 105 the other ASNs may be defined as an R4
reference point, which may include protocols for coordinating the
mobility of the WTRUs 102a, 102b, 102c between the RAN 105 and the
other ASNs. The communication link between the core network 109 and
the other core networks may be defined as an R5 reference, which
may include protocols for facilitating interworking between home
core networks and visited core networks.
[0097] Embodiments may provide Long DRX cycle length definition and
configuration of the long DRX cycle for MTC devices. Some MTC
devices require low power consumption. Thus, frequent monitoring,
paging, and/or listening to system information may unnecessarily
waste the battery power of these MTC devices. Extended DRX cycle or
the long DRX cycle length units may be used for these types of MTC
devices to enable these devices to sleep/DRX under scheduling or
configuration.
[0098] A long DRX cycle may be provided. To accommodate the long
DRX cycle operation, one or more cycle length base units may be
described herein. A long DRX cycle may be one or more of the base
units.
[0099] To align with the current 3GPP wireless DRX cycle base unit,
a long DRX cycle length unit may be based on an SFN cycle. For
example, one or more of the SFN cycle(s) may be used as the base
unit. This may be referred to as an extended SFN cycle(s). A long
DRX cycle length, which may be the extended SFN cycle, may be of n
SFN cycle(s), where the n value may be:
[1, 2, 4, 8, . . . ] or [1, 3, 6, 12, . . . ] or [k.sup.mb, where
k=2, 3, 4, . . . and m=0, 1, 2, . . . and b=1, 2, 3, 4, . . . ],
etc
[0100] The n value or the values used for deriving n, such as k, m,
and b, may be predefined or network configured. The long DRX cycle,
the extended DRX cycle, or the long-deep-sleep period may consist
of one or more of the extended SFN cycles described herein.
[0101] To align with possible MTC operation service time
definitions, a long DRX cycle, an extended DRX cycle, or a long
deep sleep period unit may be based on time units or calendar time
units, such as a second, a minute, an hour, a day, a week, a month,
a combination of those units, or the like. For example, a long DRX
cycle may be two-days, two-weeks, or one-month-plus-two-days, etc.
Depending on the service the MTC device may be configured for, the
network may assign the MTC devices with service specific extended
DRX cycle length. A system may use broadcast or MTC specific
messages to convey the MTC extended DRX cycle and parameters to MTC
devices. When using a time unit for sleep/DRX in a configuration
and if the configured time does not start or end on an SFN cycle
boundary, then the counting of the start and the end of such a time
unit may be rounded forward to the next SFN cycle boundary.
[0102] To align with the MTC service time and to facilitate DRX
operation with frame-based 3GPP DRX operations, a combination of
the two units described above may be used, i.e. the time
unit(s)+the extended SFN cycles. For example, a long DRX cycle
length unit (definition-C) may be 2-week+5*extended SFN cycles or
may be one-week+7*SFN cycles. This may be used to provide a long
DRX cycle that may have a length of in days and a low activity
period of the day. A mechanism may be provided to distribute the
MTC device evenly among the low activity period in the
extended/long DRX cycle.
[0103] To ensure that an MTC server may have a chances to trigger a
MTC device, the system may configure the MTC device to stay in a
normal DRX cycle for some time after one or more long DRX cycles.
For example, the long DRX cycle may be a three-tuple, such as:
[0104] extended DRX cycle=number of Day+low Activity
Period+OnTimePeriod where the "number of Days" may be the days of
the extended DRX cycle, the "low Activity Period" may be the period
of low activity during the day (e.g. 4 am), and the "OnTimePeriod"
may be the length of time the WTRU may monitor the paging over a
shorter or regular DRX.
[0105] A Total-DRX-Definition-Period may be provided. The
Total-DRX-Definition-Period may be a multiple of a long DRX cycle.
The Total-DRX-Definition-Period may be a combination of some
multiples of the DRX base units described herein. For example, a
Total-DRX-Definition-Period may be based on an extended SFN cycle,
a time unit, a calendar time unit, or combination of an extended
SNF cycle and a time unit, or any combination thereof, or the
like.
[0106] A Total-DRX-Definition period may be as a combination of one
or more of the descriptions provided in the following
paragraphs.
[0107] A Total-DRX-Definition-Period may be a multiple of an
extended SFN cycle base unit as described herein. For example, the
Total-DRX-Definition-Period may be a multiple of an extended SFN
cycle, such as 32 extended SFN cycles. A
Total-DRX-Definition-Period may be a combination of an extended SFN
cycle and a base unit, such as 36 extended SFN cycle plus 12-SFN
cycles. If the Total-DRX-Definition-Period may be m extended SFN
cycles, each with (n) SFN cycles, the Total-DRX-Definition-Period
may have (m*n) SFN cycles. This may be numbered as [0, 1, . . .
m.times.n-1]. If the Total-DRX-Definition-Period may be a
combination of multiples of some of the base units described
herein, then the Total-DRX-Definition-Period may have a combination
of (j) extended SFN cycles and (k) SFN cycles and it may have
(j*n)+k SFN cycles. This may be numbered as [0, 1, . . . , j*n,
j*n+1, j*n+2, . . . j*n+k-1]. The MTC device, such as a WTRU, and
the network supporting the long-DRX operation may count the SFN
Cycle Number (SCN) from 0 to the end of the
Total-DRX-Definition-Period (i.e. the m*n-1 or the j*n+k-1 SFN
cycles) and may wrap-around to the next period from the 0 SFN cycle
again.
[0108] A Total-DRX-Definition-Period may be a base unit, such as
6-months, or a combination of multiples time units, such as
9-months plus 12-weeks. In some scenarios, the conversion of the
Total-DRX-Definition-Period to the number of extended DRX cycle or
the number of SNF cycles may be rounded up to the nearest Extended
DRX cycle or to the nearest SNF cycle.
[0109] A Total-DRX-Definition-Period may be some combination of the
base units described herein, such as a combination of an extended
SNF cycle and a time unit. For example, the
Total-DRX-Definition-period may be 24 weeks plus 42 extended SFN
cycles. In some scenarios, the conversion of the
Total-DRX-Definition-Period to the number of extended DRX cycle or
the number of SNF cycles may be rounded up to the nearest extended
DRX cycle or to the nearest SNF cycle.
[0110] A Total-DRX-Definition-Period may also be a combination of
any of the embodiments described herein. MTC device configurations
may be provided for utilizing the long DRX cycle. As described
herein, the Total-DRX-Definition-Period and the Long-DRX-base-units
(which may include the extended SFN cycle, a base unit, or
combinations thereof) may provide MTC devices for long dormant
periods of sleep that may preserve power. The
Total-DRX-Definition-Period and/or the long DRX base unit may be
configured for a MTC device to allow the device to operate in a
discontinuous reception mode, idle mode, an offline mode, or the
like. This may allow the MTC device, such as a WTRU, to identify
its paging time after the long sleep or long DRX.
[0111] A formula may be used for scheduling a page/signal/reach for
a MTC device that may have been in a long sleep. For example, one
or more SFN cycle(s) may be identified in a
Total-DRX-Definition-period such that the network may page the
device in that cycle and the device may perform monitoring and
reception. The SNF cycle may also be identified such that the MTC
device may find its paging frame(s) and the paging subframe
occasion(s) either with the an idle mode paging reception formula
or with some other formula or rules.
[0112] For example, a WTRU may obtain the monitoring/reception
N.sup.th SFN cycle while configured for long DRX or long deep sleep
using the following:
SCN % ConfiguredLongDRXCycleLength=OffsetSCN, [0113] where the SCN
may be the counting of the SFN cycle number, described herein,
within the Total-DRX-Definition-Period; [0114] the
ConfiguredLongDRXCycleLength may be the extended DRX cycle or the
long DRX cycle length configured to the WTRU in numbers of SFN
cycles; and [0115] the OffsetSCN may be an offset in unit of SCN
given by the network
[0116] As shown in FIG. 2, a shorter DRX cycle may be scheduled
inside a long DRX cycle. Temporary network congestion or RAN
resource jamming may cause a MTC device, such as a WTRU, to miss a
network paging or signal after a long-sleep. For the network and/or
the MTC device to avoid missing a network paging or signaling after
a long-sleep, a short DRX cycle within a long DRX cycle may be
configured. The short DRX cycle may be configured in a second long
DRX cycle that may occur after a first long DRX cycle. For example,
as shown in FIG. 2, long DRX cycle 202 may be configured such that
it may not include one or more short cycles. Long DRX cycle 204 may
occur after long DRX cycle 202. One or more short DRX cycles may be
configured within long DRX cycle 204, such as short DRX cycles 206.
A short DRX cycle, such as short DRX cycles 206, may be used, for
example, to provide occasions for a network to re-transmit and/or
for a WTRU to re-receive a signal. Network paging/signaling
repetitions may run with the one or more short DRX cycles from
short DRX cycles 206. Network paging/signaling may be scheduled
from the long DRX cycle boundary.
[0117] A network may configure a WTRU with a long DRX cycle, which
may be followed a number, M, DRX cycles. After a MTC device, such
as a WTRU, wakes up from a long DRX, it may use a short DRX cycle
for a period of time.
[0118] Configured LongDRXCycleLength may be a multiple (m) of the
ShortDRXLength in the following formula such that the short DRX
occasions may be on the SCNs with ((SCN-OffsetSCN) %
ConfiguredLongDRXCycleLength)=(n*ShortDRXLength), where n=(1, 2, .
. . m-1) configurable.
[0119] Short DRX cycles may be placed before, around, or after a
long DRX cycle boundary; before, around, or after a scheduled
paging SFN cycle; or before, around, or after the network
paging/signaling frames. These schedules may be configured by the
WTRU or the network. Network paging/signaling may be scheduled at
those boundary, cycle, or frames.
[0120] As shown in FIG. 3, short cycles may be used in between long
DRX cycles. A network may configure a WTRU with an extended/long
DRX cycle followed with m number of DRX cycles. In this
configuration, after a MTC device wakes up from the extended DRX,
it may take shorter DRX cycles for a period of time and then may
start another long or extended DRX cycle. For example, as shown in
FIG. 3, extended DRX cycle 300 may be scheduled. Short DRX cycles
302 may be scheduled after extended DRX cycle 300. Extended DRX
cycle 304 may be scheduled after short DRX cycles 302.
[0121] The MTC device may be configured with an extended DRX cycle
that may follow the extended DRX cycle in idle mode. If the
extended DRX cycle may be configure through a WTRU dedicated
message, a network may configure a MTC device with an extended DRX
cycle using a RRC message, or a NAS message. For example, a WTRU
may trigger a tracking area update (TAU) procedure and may send a
TAU message to the network. In the message, the WTRU may indicate
its ongoing MTC applications. Based on the ongoing WTRU
applications, or the changes in the ongoing WTRU applications, the
network may configure the MTC device with an extended DRX cycle or
may modify the configured extended DRX cycle.
[0122] When MTC device is configure with extended DRX cycle, MTC
device may calculate its wake up time. For example, the MTC may use
the following formula:
StartTime=(number of Day) % (LongDRXCycleUnit)+low Activity Start
Time+(low Activity length) % (LongDRXCycleUnit)
where LongDRXCycleUnit may be a number that given by the system or
calculated from UeID.
[0123] An uneven sleep period assignment may be provided. For MTC
devices, the uneven sleep period or periods may be assigned by the
network to the WTRU such that the WTRU may sleep for a different
period from time to time according to the assigned long sleep
length. For example, a WTRU may sleep for 5 hours, wake up, and
then may sleep for 5 months. The uneven sleep period may be
assigned by a message or may be assigned by rules. The uneven sleep
period(s) may be assigned one a time or several uneven periods may
be assigned at once.
[0124] DRX cycle configuration may be provided. DRX configurations
determination may be provided by an operator. Information may be
obtained from the SCS before calculating the DRX cycle. A MTC-IWF
and a SCS may be informed of the DRX configuration.
[0125] A SCS may initiate a DRX cycle configuration. FIG. 4 depicts
a method for DRX configuration that may be initiated by a SCS. The
allowable length of a long DRX cycle may depend on an application
and may be dynamic. When an MTC device first connects to a network,
the network may assume that the device may be using existing DRX
methods. When the MTC device application registers with the SCS,
the SCS may indicate the application requested sleep parameters to
the core network and RAN (eNB or RNC). The RAN (eNB or RNC) may
then calculate the long DRX cycle parameters that may be used by
the device.
[0126] For example, as shown in FIG. 4, at 416, MTC WTRU 402 may
register with a core network, which may include RNC/eNodeB 404,
MSC/SGSN/MME 406, and HSS 408. Subscription information for MTC
WTRU 402 in HSS 408 may include an indication that MTC WTRU 402 may
support Long DRX. A long DRX cycles may not have been configured.
At 418, one or more MTC Applications on MTC WTRU 402 may register
with the service layer using application/service layer procedures,
which may involve RNC/eNodeB 404, MSC/SGSN/MME 406, HSS 408,
MTC-IWF 410, and SCS 412. At 420, SCS 412 may register the
application(s) DRX parameters with the core network. This
information may be passed to MTC-IWF 410 via, for example, a Tsp
reference point. This may occur, for example, using a message on
the Tsp reference point. This message may be provided as shown in
Table 1:
TABLE-US-00001 TABLE 1 Application DRX Request Message Information
Element M/O Description Device External M The device external ID
(e.g. MSISDN, FQDN, Identifier etc) Note: This field may be
populated with a group identifier so that the SCS may request DRX
parameters for a group of devices. SCS Identifier M The SCS ID
(e.g. MSISDN, FQDN, etc) Application O The application ID (e.g.
Port Number, SCS Identifier assigned name, etc.) Note: This field
may be populated with a group identifier so that the SCS may
request DRX parameters for a group of applications. Max Off Time O
The maximum amount of time that the appli- cation may be allowed to
sleep. The units of this field may be seconds or some period of
time. Min On Time O The minimum amount of time that the device may
stay on when coming out of sleep. The units of this field may be
seconds or some period of time. Mandatory O Periods of the day when
the device may be On Times reachable. The units of this field may
be seconds or some period of time. Permitted O Periods of the day
when the device may not Off Times be reachable. The units of this
field may be seconds or some period of time.
[0127] Referring again to FIG. 4, at 424, MTC-IWF 410 may use an
S6m reference point to resolve the device and SCS identifiers to
subscription identifiers. The MTC-IWF may also identify the serving
node of the device. This may include a check of the HSS
subscription parameters to verify that MTC WTRU 402 supports long
DRX cycles. At 426, MTC-IWF 410 may pass updated DRX information to
the serving node using, for example, a T5 reference point. This may
be done, for example, using a message, such as the message shown
below in Table 2:
TABLE-US-00002 TABLE 2 Application DRX Update Message Information
Element M/O Description Device Internal M The device internal ID
(e.g. IMSI) Identifier Note: This field may be populated with a
group identifier so that the SCS may request DRX parameters for a
group of devices. MTC-IWF M IP Address, SS7 address, ISDN, etc.
Identifier Application O The application ID (e.g. Port Number, SCS
Identifier assigned name, etc.) The serving node or RAN may use
this ID to keep track of the multiple applications that may be on a
device and how their DRX parameter re- quests may overlap. Note:
This field may be populated with a group identifier so that the SCS
may request DRX parameters for a group of devices. Max Off Time O
The maximum amount of time that the appli- cation may be allowed to
sleep. The units of this field may be seconds or some period of
time. Min On Time O The minimum amount of time that the device may
stay on when coming out of sleep. The units of this field be
seconds or some period of time. Mandatory O Periods of the day when
the device may be On Times reachable. The units of this field may
be seconds or some period of time. Permitted O Periods of the day
when the device may not Off Times be reachable. The units of this
field be seconds or some period of time.
[0128] At 428, the serving CN node may use an Iu or S 1-MME
reference point to pass the updated DRX information to the RAN.
This may be done using, for example, a NAS message that may be sent
to the RAN, which may include the information shown in Table 2 (the
MTC-IWF address may not be requested). At 430, DRX parameters may
be calculated and the device may be configured with the DRX
parameters. The CN serving node may inform/configure the MTC device
directly with a NAS message, such as described above, on the long
DRX or long sleep activity.
[0129] At 432, the RAN may pass the DRX parameters to the serving
node via the Iu or S 1-MME reference points. This message may
include the information that may be shown in Table 2. The MTC-IWF
address may not be included. The RAN may configure the device with
parameters that may be different than what was requested. Different
parameters may be selected due to network congestion or the RAN may
select different parameters in order to accommodate other
applications on the same device may have different DRX parameter
requests (i.e. another application may request to be on at
different times).
[0130] At 434, the serving note may pass DRX parameters received at
432 to MTC-IWF 410. This may be done, for example, using a T5
reference point. MTC-IWF 410 may store updated DRX parameters so
that it may manage trigger requests. At 436, MTC-IWF 410, may send
the DRX parameters to SCS 412 using, for example, a Tsp reference
point. The DRX parameters may be different than what may have been
requested at 420.
[0131] DRX cycle configuration may be initiated by a WTRU or a RAN.
FIG. 5 depicts a method for DRX cycle configuration that may be
initiated by a RAN. When network conditions change, when an MTC
devices moves, or when an MTC application wakes up, the WTRU or RAN
may reconfigure a DRX cycle for the WTRU. When the WTRU and RAN
(eNB and RNC) change the DRX parameters for the WTRU, the SCS may
be informed.
[0132] As shown in FIG. 5, at 516, MTC WTRU 504 and a RAN, such as
RNC/eNodeB 504, may negotiate a DRX cycle. This may be initiated by
the WTRU or the RAN (eNB or RNC). The information exchanged may be
the same as what is shown in Table 1. An MTC-IWF address may or may
not be used.
[0133] At 518, the RAN (eNB/RNC 504) may inform the serving node,
MSC/SGSN/MME 506, of the DRX cycle parameters. The serving node may
be a MSC, SGSN, or a MME. This may be done, for example, by sending
a message using the Iu and S1-MME reference points. The fields of
the message may be the same as what is shown in Table 2. An MTC-IWF
address may or may not be included.
[0134] At 520, MSC/SGSN/MME 506 may send a get MTC-IWF address
message to HSS 508. This may be done, for example, to allow the
serving node to query HSS 508 with the international mobile
subscriber identify (IMSI) for a device for the MTC-IWF, such as
MTW-IWF 510, that may be used to reach the SCS, such as SCS 512,
that the device may be registered to. The message may be sent on an
S6m reference point.
[0135] At 522, MSC/SGSN/MME 506 may inform MTC-IWF 510 of the DRX
cycle parameters. This may be done, for example, sending a message
using the T5 reference point. The fields of this message may be the
same as what may be shown in Table 2.
[0136] At 524, MTC-IWF 510 may inform SCS 512 of the DRX cycle
parameters. This may be done, for example, by sending a message
using on the Tsp reference point. The fields of this message may be
the same as what may be shown in Table 1.
[0137] DRX cycle configuration may be initiated by a WTRU or a RAN.
For example, the SCS may be informed of a DRX cycle for a device.
FIG. 6 depicts another method for DRX cycle configuration that may
be initiated by RAN.
[0138] As shown in FIG. 6 at 618, MTC WTRU 602 and a RAN, such as
RNC/eNodeB 604, may negotiate a DRX cycle. This may be initiated by
the WTRU or RAN (eNB or RNC). The information exchanged may be
similar to what may be shown in Table 1. The MTC-IWF address may or
may not be used.
[0139] At 620, the service layer of MTC WTRU 602 may inform SCS 612
of a DRX update over a user plane connection. This communication
may happen between service layers (i.e. European Telecommunications
Standards Institute (ETSI)). This message may include the fields
that may be shown in Table 1. The MTC-IWF address may or may not be
used. MSC/SGSN/MME 606 and MTC-IWF 610 may not be informed of the
of the DRX cycle. SCS 612 may be trusted not to continuously
attempt to contact the device when it may be sleeping.
[0140] Device trigger requests may be provided. For example, device
triggering procedures may occur over a Tsp reference point. The
procedures on this interface may be updated to account for the
where a SCS may attempt to trigger a device that may be in a long
DRX cycle. The MTC-IWF may choose to reject or buffer the trigger
request. For example, the device may not be scheduled to be awake
for several hours and MTC-IWF policies may determine how long the
MTC-IWF may buffer triggers.
[0141] If the MTC-IWF chooses to reject the trigger request, the
MTC-IWF may send the SCS a Device Trigger Confirm message with a
value that may indicate that the request may be rejected because
the device may be in a long DRX cycle. The Device Trigger Confirm
message may indicate a time when the trigger may be attempted
again.
[0142] If the MTC-IWF chooses to cache the trigger request until
the device may be reachable, the MTC-IWF may send the SCS a Device
Trigger Confirm message with a value the may indicate that the
request may be buffered because the device may be in a long DRX
cycle. The Device Trigger Confirm message may indicate an estimate
as to when the trigger may be delivered. The SCS may know the DRX
cycle of the MTC applications that may be registered to it. The SCS
may avoid making triggering requests to an application that may not
be reachable.
[0143] DRX classes may be provided. To reduce the amount of
signaling inside of the CN, between the CN and SCS, or between the
WTRU and RAN, a set of DRX classes may be defined. The Max On and
Max Off times of Table 1 may then be determined by a predefined
class number. An example may be shown in Table 3. The predefined
classes may be used to determine the duty cycle of the DRX cycle,
and may not be used to determine when the duty cycle starts.
TABLE-US-00003 TABLE 3 DRX Class Example Class MIN ON MAX OFF
Number TIME TIME Example Use-Case 0 30 Seconds 1 Hour Environmental
Sensor, Asset Tracking 1 1 Minute 23 Hour Smart Meter, Patient
Surveillance 2 10 Minutes 1 Week Retail Monitoring, Product
management, Vehicle diagnostics 3 15 Minutes 1 Month Disaster
Detection (sensor may initiate contact at any time - SCS may
initiate contact one a month)
[0144] An adjustment-window may be defined from the length of the
scheduled long-sleep period. The WTRU and/or network may perform
procedures for the adjustment. A receiving window or an
adjustment-window may be defined at the WTRU side and may be used
interchangeably. With the receiving window, a WTRU may monitor the
paging channel as it may do in an IDLE state. The receiving window
may start as a WTRU may wake up from the long sleep and the window
may end when the WTRU may have received the paging or may end after
a period of time (such as a receiving window length). The receiving
window length may be predefined, indicated by the network, or
calculated from the long sleep period. When the receiving window
starts, WTRU may perform synchronizing with the network, reading
MIB and SIBs. The WTRU may start monitoring the paging channel with
a DRX cycle, which may be a paging cycle. The paging occasions may
be related to SFN. Since the WTRU and the network may be
synchronized with SFN, the WTRU may not miss the paging. The
receiving window length for the WTRU may be long enough to cover
the drifted time and the receiving window for the WTRU may start
earlier than the network starts the transmitting window.
[0145] An adjustment window may be defined from the length of the
scheduled long sleep period. When a MTC WTRU goes dormant, it may
not perform any activities that may involve contact with the
network to save power. For example, the MTC WTRU may not perform
measurement of the cell or perform any mobility area update. The
WTRU may not have a chance to learn the network timing and adjust
its own clock and the WTRU clock may drift from the network clock.
This may occur at a certain rate and may depend on the make of the
clock. The longer the MTC WTRU may sleep, the more it may drift
from the network timing on which the activity of communication
synchronization may be based.
[0146] When the long sleep MTC WTRU wakes up for a scheduled
activity with the network, it may fail because of missed timing or
synchronization. This may occur, for example, with schedule
activities such as monitoring or receiving network paging or work
signals. This may also occur when accessing the network.
[0147] An adjustment window period may be provided to avoid missed
timing or synchronization due to clocking drifting during a long
sleep period. During the adjustment window period, the MTC WTRU
and/or the network may take action to resynchronize or to remediate
the negative impact of the missed timing.
[0148] The adjustment window may be defined as a function of the
long sleep period and the clock drift rate, known or estimated:
Adjustment window
length=Long-Sleep-Length*ClockDriftRate+RoundUpTime
where the RoundUpTime maybe predefined, configured or a value
related to the Long-Sleep-Length or the ClockDriftRate
[0149] The adjustment window may also be defined using the
following formula:
Adjustment window length=(Long-Sleep-Length*ClockDriftRate)*N
where the N could be [1, 1.2, 1.4, 1.6, . . . , 2].
[0150] The adjustment window length unit may be a unit such as the
LTE SFN cycle, an LTE frame, or the like. The length of the
receiving window (i.e. the adjustment window) length may also be a
value of time (e.g. 512 ms), a number of default paging cycles
(e.g. 2.times.Paging Cycles), a number of radio frames (e.g.
20.times.Radio Frames), or the like.
[0151] The receiving window length or the ClockDriftRate may be
broadcasted in the system information.
[0152] A network may start paging before the calculated receive
window starts in a WTRU and may use a longer window length to cover
the drifted time to make the paging more reliable.
[0153] A WTRU may determine a window length to be used for the
WTRU. The WTRU may notify the network of its receiving window
length or the clock drift rate in the initial Attach or TAU
message. In this case, the network paging message may also carry
the receiving window length or clock drift rate information.
[0154] WTRU and network procedures may be performed during the
adjustment window. FIG. 7 depicts network and WTRU procedures for
busy reaching and/or monitoring. The network, such as network 702,
and a long sleep WRTU, such as WTRU 708, may avoid an issued caused
by clock drift when the WTRU has computed the adjustment window
length (i.e. the drift estimates). At 706, network 702 may employ a
Busy Reaching Window around scheduled wake up time 704, which may
be a boundary of a Long DRX cycle such as Long-DRX cycle 715.
During Busy Reaching Window 706, the network may send paging or
other reaching signal to a WTRU that may be waking up from a long
sleep. The length of Busy Reaching Window 706 may be based on the
estimated longest adjustment window length. For example, three
quarters, one, one and one half or twice the length of an estimated
longest adjustment window length may be used for the length of Busy
Reaching Window 706; however, any length may be used. Network 702
may place Busy Reaching Window 706 centered on scheduled wake-up
time 704 (in FIG. 7 centered O). Busy Reaching Window 706 length
may be predetermined or configured and may be broadcast to the
WTRUs via system information.
[0155] Busy Reaching Window 706 may be selected to be as short as
may be possible to reduce overhead and inefficiency. Additionally,
Busy Reaching Window 706 may not be employed if the WTRU clock does
not drift.
[0156] At 710, WTRU 708 may know its clock drift direction. That
is, WTRU 708 may know whether its clock may drift towards shorter
time (-drift) or towards longer time (+drift). The adjustment
window or the drift window may be used to compensate the long DRX
cycle counting (i.e. add the drift length if the "-drift" and
subtract the drift length if the "+drift"), so WTRU 708 may know or
learn approximately when scheduled wake-up time 704 may be. WTRU
708 may then configure WTRY Busy Monitoring Window 716 around or
centered the estimated the scheduled wake-up time, which may
overlap the network busy reaching window for activity. WTRU Busy
Monitoring Window 716 may be any length. For example, WTRU Busy
Monitoring Window 716 may be one or one and one half or twice of
the computed adjustment-window length.
[0157] At 712 and 714, WTRU 708 may not know the clock drift
direction. WTRU 708 may set the length of a WTRU Busy Monitor
Window, such as WTRU Busy Monitor Window 718 and WTRU Busy Monitor
Window 720, to at least twice the computed adjustment window
length. WTRU 708 may start the Busy Monitoring Window, such as at
722 and 724, one adjustment-window earlier than the scheduled wake
up time, such as at 726 and 728, so that approximately half of the
Busy Monitoring Window or one adjustment-window time may overlap
with the network Busy Reach Window for activity. For example, WTRU
Busy Monitor Window 718 and/or WTRU Busy Monitoring Window 720 may
overlap with Network Busy Reaching Window 706.
[0158] During period of the Busy Reaching Window 706, network 702
may send paging or other signaling at the configured normal paging
frames (PF) and paging subframe occasions (PO) in any of the SFN
cycles within the period, which may be in addition to the PFs and
POs in the scheduled SFN cycle. During the period of the Busy
Monitoring Window, such as at 716, 718, and/or 720, WTRU 708 may
perform the monitoring and reception of the scheduled network
paging or signaling in any SFN cycle during the period in the PFs
and POs configured by network 702 in terms of "paging" and
signaling.
[0159] To assist this busy compensation method, network 702 may
store information regarding WTRU 708 its associated
adjustment-window length in an MME when the long sleep DRX or sleep
is configured. For example, when a WTRU may be configured for long
sleep, the network may save a copy of WTRU information and the
adjustment-window-length in the MME node. This WTRU information may
be used by the network to provide the busy window to the WTRU.
[0160] The WTRU may flag this long sleep nature of the operation
and the possible clock drift rate related indication to the network
when the WTRU registers with the network.
[0161] Network assisted SFN cycle adjustment methods may be
provided. The network may provide information that may assist a
WTRU that may have woken-up to self-adjust to the scheduled SFN
cycle for the network paging or signaling.
[0162] The network may publish a SFN cycle order number within the
Total-DRX-Definition-Period in the system information. This may be
done, for example, so that when the long sleep WTRU wakes up, it
may use the network published SFN cycle order number to align its
own SFN cycle to the network SFN cycle number. The WTRU may then
perform the monitoring of the PFs and POs in the right SFN cycle
for the network paging or signaling.
[0163] The network may provide the current
count-number/order-number of the SFN cycle (e.g. the 15.sup.th or
the 234.sup.th SFN cycle within the Total-DRX-Definition-Period) to
the public or to the MTC devices. When the long sleep WTRU wakes
up, it may use the SFN cycle count-number/order-number from the
system information to adjust its number/order of the SFN cycle with
the systems. This count-number/order-number quantity in the system
may take a log.sub.2(SCN.sub.inTotalDRXDefinitionPeriod) bit
quantity in the SIB space, e.g. 18 bit for a wrap-around period in
31 days. Depending on the space the SCN order number may take and
the urgency of WTRU realignment to the order of the SFN cycle, the
system may publish it eight to sixteen times per SFN cycle evenly
distributed.
[0164] Another method may be to have the system indicate a local
SFN cycle (from 0 to 2.sup.n-1) order number it may be in (where
n=1 or 2 or 3) to help the WTRU that may have woken up to figure
out the SFN cycle number so as to tolerate the drift of 1, 2 and 4
SFN cycles. For example, if the WTRU may wake up at the SFN-0 of
the beginning of SFN cycle 0 and let n=1, the network indication
(which may be a SIB bit) of the SFN cycle order may be an
alternating 0 and 1.
[0165] FIG. 8 depicts local SFN cycle order number 0 and 1. For
example, FIG. 8 shows a drift range 0 case at 802 that with a 0 on
the SFN cycle 0 at 804, a 1 on SFN cycle 1 at 808, and a 1 on SFN
cycle -1 at 806. If the WTRU wakes up and sees the network
indicating a local-SFN cycle order value of 1, it may know it may
be in the previous cycle, such as the SFN cycle -1 at 806. This may
not be cycle 1 at 808, because cycle 1 at 808 may be beyond the
basic clock drifting range assumption of no greater than .+-.1 SFN
cycle.
[0166] FIG. 9 depicts local SFN cycle order number 0, 1, 2, and 3.
In the case that the drift range may be estimated larger than one
full SFN cycle but less than two full SFN cycles, the 0 to
2.sup.n-1 (with n=2) local SFN cycle order number range
configuration may be used, i.e. the local-SFN cycle order values
would be 0, 1, 2 and 3. As shown in FIG. 9, using SFN 0 at SFN
cycle 0 (shown at 902) as the reference wake-up time, a WTRU may
see the local-SFN cycle order value 2 or 3 at 906 or 904 at wake-up
and may know that the clock may be on the left (earlier) of the
intended reference wake-up time over the time axis. A WTRU that may
see a local SFN cycle order value 0 or 1 at 908 or 910 may know it
is on the right (right or late) of the wake-up reference time.
Using a localized-SFN cycle-number indication may cost less
signaling overhead than the order number uses (e.g. 18 bits).
[0167] A system may provide time information. The network system or
the eNB may provide the time+n-SFN cycle based long DRX cycle
adjustment information to a MTC WTRU. For example, the eNB may
provide SIB-8 or an equivalent for the time information. The eNB
may provide the Nth SFN cycle order number in the intervals of a
day or a half day or a time interval, such as a hour, minute, or
the like via SIB or a message. A NAS may provide a universal time
and a local time zone to a MTC device when the MTC device may
access the network, such as a periodic TAU. A network may reuse EPS
mobility management (EMM) information message or may include the
universal time information element (IE) in the TAU accept message
or other NAS message. The WTRU may obtain the time information
using any of the methods described herein
[0168] A WTRU may perform autonomous synchronization of SFN and/or
SFN cycle. A SFN Sync Timer may also be pre-configured in a WTRU.
The timer may be a configured fixed value or the timer value may be
adjusted with respect to the cycle end based on previous
measurement. When the timer expires, the WTRU may wake up, read and
align the SFN, and may align the SFN cycle with the network.
[0169] The timer may be counting the SFN cycles; the value of the
timer may be the integer times of SFN cycle. The value of the timer
may ensure that the timing drift in the WTRU may not be greater
than 512 radio frames before the timer expires. However, the timer
may also be configured to stop at the turn of the SFN cycles (i.e.
SFN=0), or stop in the middle of a SFN cycle or any other frame
number within a SFN cycle.
[0170] If the SFN Sync timer for the WTRU expires (i.e. the WTRU
"wakes up"), the SFN sync timer may be reset and restarted again at
the SFN cycle boundary after WTRU goes back to sleep.
[0171] If the WTRU clock and the network clock may not or may not
be estimated to drift apart beyond plus/minus 512 SFNs (.+-.5.12
seconds), the MTC WTRU may resynchronize with the network by
itself.
[0172] Self-recovery schemes described herein may be used if the
estimated drift, or the computed adjustment window show that the
clock drift may be within half (512 SFNs) of the SFN cycle.
[0173] FIG. 10 depicts WTRU clock realignment. At 1001, a WTRU may
be scheduled during long DRX cycle 1006 to wake up in the middle of
a SFN cycle, such as at SFN cycle -1 at 1002, which may be between
frame number (FN) 500 to FN 524. This may be prior to SFN cycle 0
at 1004 where the network may be scheduled to send paging or
signaling to the WTRU in the early half of the SFN cycle. The WTRU
may align itself (its clocking) with the network on the LTE frame
numbers via MIB and SIB acquisition. The WTRU may get ready to
monitor/receive the network paging in the next SFN cycle (SFN cycle
0) on the PFs and POs scheduled and configured.
[0174] FIG. 11 depicts another WTRU clock realignment. At 1100, a
WTRU may be scheduled to wake up at the end of long DRX cycle 1102
to the SFN cycle (SFN cycle 0, SFN=0). The network may be scheduled
to send paging or signaling to the WTRU in the latter half of the
SFN cycle at 1104. When the sync timer expires and the WTRU may the
network SFN, the SFN cycle may be aligned by comparing the stored
SFN (=0) on the WTRU with the derived network SFN. If the derived
SFN>=512, then the SFN cycle for the WTRU may fall in the
previous SFN cycle (SFN cycle -1) for the network, such as at 1106.
If the derived SFN<=512, then the WTRU and the network may be in
the same SFN cycle (SFN cycle 0), at 1108. The WTRU may be able to
adjust or confirm its SFN cycle and the LTE frame number, and may
be ready to monitor/receive the network paging/signaling at the
scheduled PF and PO.
[0175] Network paging coordination may be performed with respect to
the receiving window. Upon the start of the receiving window (i.e.
wake-up from the long sleep), the WTRU may follow camping
procedures and may start monitoring the paging channel
discontinuously. The paging cycle during the period of the
receiving window may be the normal default paging cycle, or it may
be the WTRU specific paging cycle. The paging occasion may be
calculated.
[0176] If the network has a paging message waiting for the UE, it
may delay the transmission of the paging message until the WTRU may
be within the receiving window. The calculated start of the
receiving window for the WTRU at the network side may not be
exactly aligned with the start of the receiving window for the WTRU
at the WTRU side due to the clock shift. By implementation, the
network may start transmission in advance to the start of window
and may extend the length of the window to make the paging delivery
more reliable.
[0177] A network system may keep alive time. The system may depend
on periodic TAU to know whether the concerned device may still be
up to its designated or prescribed functions or technically alive.
To preserve the keep-alive-time in the network system while
implementing a long DRX cycle scheme, the longest periodic TAU
timer may be longer than the longest long DRX cycle, for example,
twice as long.
[0178] The MTC WTRU configured with the long DRX cycle may use the
wake up time to perform the periodic TAU if the long periodic TAU
timer expires between two scheduled wake-up times with one long DRX
cycle.
[0179] Those MTC WTRUs that may usually be offline with the long
DRX cycle may register or attach themselves with a flag that may
indicate their long-dormant operational nature. The network system
may then not rely on the periodic TAU to maintain their functional
status. The monitoring of those MTC WTRUs may be the responsibility
of the MTC-server or the relevant MTC-applications.
[0180] A MTC WTRU may have multiple applications running and a MTC
server may know the status of those applications. The network or
the MTC server may configure the MTC WTRU to report the status of a
configured application. The report may be done in several ways. The
MTC WTRU may report application status directly to MTC server on a
PDN connection. The MTC WTRU may report application status using
SMS. MTC application status may be combined with alive time method
and the MTC application status may be attached in the NAS message.
After receiving the MTC WTRU application status via a NAS message,
a MME may forward the status report to MTC server. The MTC device
may report application status by synchronizing its time with
network when it access to the network.
[0181] A WTRU may be provided. The WTRU may include a processor
that may be configured to perform a number of actions. For example,
the processor may be configured to determine a cycle base unit type
and a length of a long discontinuous reception (DRX) cycle. A
number of base units of the cycle base unit type may be generated
using the length of the long DRX cycle. The cycle base unit type
may be an extended subframe number (SFN) cycle type, a time unit
type, or the like.
[0182] The processor may be configured to generate the number of
base units of the cycle base unit type using the length of the long
DRX cycle in a number of ways. For example, the processor may
determine n number of SFN cycles to be used for an extended SFN
cycle type base unit. A number of extended SFN cycles to make up
the length of the long DRX cycle may be generated. Each extended
SFN cycle in the number of extended SFN cycles may include n SFN
cycles. As another example, the processor may determine a length of
time for the time unit type. A number of time units to make up the
length of the long DRX cycle may be determined. The number of time
units may be generated. Each time unit in the number of time units
may include the length of time for the time unit type.
[0183] A long DRX cycle may be generated from the number of base
units. For example, the long DRX cycle may be generated from the
number of base units by generating the long DRX cycle from the
number of extended SFN cycles.
[0184] A WTRU may be provided for determining when to receive a
signal. The WTRU may include a processor that may be configured to
perform a number of actions. For example, the processor may be
configured to determine a system frame number cycle number (SCN)
within a total DRX period. A long DRX cycle length may be
determined. An offset SCN may be generated using the SCN and the
long DRX cycle length. A page timing may be determined using the
offset SCN. A paging signal may be received from a network using
the page timing. A number of short DRX cycles may be determined to
be used to receive the paging signal.
[0185] A long DRX cycle may be scheduled using the offset SCN and
the long DRX cycle length. For example, the number of short DRX
cycles may be scheduled within the long DRX cycle using the short
DRX cycle length, before the long DRX cycle using the short DRX
cycle length, after the long DRX cycle using the short DRX cycle
length, or the like.
[0186] A number of short cycles may be scheduled and may be used to
receive the paging signal. For example, a first long DRX cycle and
a second long DRX cycle may be scheduled using the offset SCN and
the long DRX cycle length. The number of short DRX cycles may be
scheduled between the first long DRX cycle and the second long DRX
cycle.
[0187] A WTRU for minimizing clock drift impact may be provided.
The WTRU may include a processor that may be configured to perform
a number of actions. For example, the processor may be configured
to determine a long sleep length, a clock drift rate for the WTRU,
and a wake-up time. An adjustment window may be generated using the
long sleep length, the clock drift rate, and the wake-up time. A
clock drift direction may be determined A signal maybe received
from a network using the adjustment window.
[0188] The processor may be configured to generate the adjustment
window using the long sleep length, the clock drift rate, and the
wake-up time. For example, the processor may determine the
adjustment window using the long sleep length. The adjustment
window may be scheduled using the wake-up time. The adjustment
window may be adjusted using the clock drift rate such that a
signal may be received from a network during the adjustment
window.
[0189] As another example, the processor may be configured schedule
the adjustment window using the wake-up time. A length of the
adjustment window may be decreased using the clock drift rate when
the clock drift direction indicates that a clock is drifting
towards longer time. A length of the adjustment window may be
increased using the clock drift rate when the clock drift direction
indicates that a clock is drifting towards shorter time.
[0190] A WTRU may be provided to adjust a SFN cycle using
assistance from a network. The WTRU may include a processor. The
processor may be configured to receive a first system frame number
(SFN) cycle order number from a network. The first SNF cycle order
number may be received from the network via a system information. A
second SFN cycle order number may be determined A drift range may
be calculated using the first SFN cycle order number and the second
SFN cycle order number. The drift range may be used to receive a
signal from the network. For example, the processor may be
configured to receive a signal from the network in a next SFN cycle
when the drift range indicates the network is scheduled to transmit
the signal in the next SFN cycle.
[0191] The processor may be configured to align a local SFN cycle
number with the first SFN cycle order number when the drift range
indicates that first SFN cycle order number and the second SFN
cycle order number may not be aligned. The aligned SFN cycle number
may be used to receive a signal from the network using the aligned
SFN cycle number.
[0192] Although features and elements are described above in
particular combinations, one of ordinary skill in the art will
appreciate that each feature or element can be used alone or in any
combination with the other features and elements. In addition, the
methods described herein may be implemented in a computer program,
software, or firmware incorporated in a computer-readable medium
for execution by a computer or processor. Examples of
computer-readable media include electronic signals (transmitted
over wired or wireless connections) and computer-readable storage
media. Examples of computer-readable storage media include, but are
not limited to, a read only memory (ROM), a random access memory
(RAM), a register, cache memory, semiconductor memory devices,
magnetic media such as internal hard disks and removable disks,
magneto-optical media, and optical media such as CD-ROM disks, and
digital versatile disks (DVDs). A processor in association with
software may be used to implement a radio frequency transceiver for
use in a WTRU, UE, terminal, base station, RNC, or any host
computer.
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