U.S. patent application number 15/046634 was filed with the patent office on 2016-06-16 for managing power consumption in base stations and remote access points.
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 Lujing Cai, Virgil Comsa, Sylvie Gomes, Joseph S. Levy, Diana Pani, Benoit Pelletier.
Application Number | 20160174150 15/046634 |
Document ID | / |
Family ID | 44306174 |
Filed Date | 2016-06-16 |
United States Patent
Application |
20160174150 |
Kind Code |
A1 |
Comsa; Virgil ; et
al. |
June 16, 2016 |
MANAGING POWER CONSUMPTION IN BASE STATIONS AND REMOTE ACCESS
POINTS
Abstract
A wireless transmit/receive unit (WTRU) in communication with a
wireless network that may include a base station (or base node) and
a cell that may be in a dormant mode is contemplated. The WTRU may
determine that the WTRU may be within a vicinity of the cell and
may generate a report that includes one or more measurements
related to a location of the WTRU. The WTRU may transmit the report
to the network and may receive an indication to perform one or more
measurements related to the cell. The one or more measurements
related to the cell may be based on a Common Pilot Channel (CPICH),
a Synchronization Channel (SCH), and/or a Broadcast Channel
(Primary Common Control Physical Channel) (BCH P-CCPCH) that may be
transmitted by the cell upon a command from a base node.
Inventors: |
Comsa; Virgil; (Montreal,
CA) ; Pani; Diana; (Montreal, CA) ; Levy;
Joseph S.; (Merrick, NY) ; Gomes; Sylvie;
(Manhasset, NY) ; Pelletier; Benoit; (Roxboro,
CA) ; Cai; Lujing; (Morganville, NJ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
InterDigital Patent Holdings, Inc. |
Wilmington |
DE |
US |
|
|
Assignee: |
InterDigital Patent Holdings,
Inc.
Wilmington
DE
|
Family ID: |
44306174 |
Appl. No.: |
15/046634 |
Filed: |
February 18, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12986677 |
Jan 7, 2011 |
9301225 |
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15046634 |
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61293432 |
Jan 8, 2010 |
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61304236 |
Feb 12, 2010 |
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61304027 |
Feb 12, 2010 |
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61355687 |
Jun 17, 2010 |
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Current U.S.
Class: |
370/311 ;
370/329 |
Current CPC
Class: |
H04L 5/0055 20130101;
Y02D 30/70 20200801; H04W 36/0088 20130101; H04W 48/16 20130101;
H04W 64/003 20130101; H04L 5/0048 20130101; H04W 36/0094 20130101;
H04W 24/10 20130101; H04W 52/0206 20130101; H04W 72/04
20130101 |
International
Class: |
H04W 52/02 20060101
H04W052/02; H04W 64/00 20060101 H04W064/00; H04W 24/10 20060101
H04W024/10; H04W 72/04 20060101 H04W072/04; H04L 5/00 20060101
H04L005/00 |
Claims
1.-15. (canceled)
16. A base node in communication with a wireless network, the base
node comprising: a processor, the processor configured to:
determine an energy-saving mode; place the base node into the
determined energy-saving mode; and provide an indication of an
energy-saving mode status.
17. The base node of claim 16, wherein the providing the indication
of the energy-saving mode status includes at least one of: setting
one or more flags in a transmitted Master Information Block (MIB),
changing a Common Pilot Channel scrambling code, sending a paging
message, or sending a dedicated message.
18. The base node of claim 16, wherein the determining the
energy-saving mode includes at least one of: determining an
energy-saving mode schedule provided by a controlling radio network
controller (CRNC) or determining a low amount of activity based on
a low activity detection algorithm.
19. The base node of claim 16, wherein the base node is a home Node
B (HNB) and the processor is further configured to transition the
base node from the determined energy-saving mode to an active mode
based, at least in part, on a Minimization Drive Test measurement
for the HNB.
20. The base node of claim 16, wherein the energy-saving mode
includes at least one of: a first energy-saving mode, wherein the
first energy-saving mode includes broadcasting only a Master
Information Block (MIB) message and System Information Block (SIB)
messages that include cell access information; a second
energy-saving mode, wherein the second energy-saving mode includes
broadcasting only a MIB message; a third energy-saving mode,
wherein the third energy-saving mode includes broadcasting only on
a Common Pilot Channel (CPICH); or a fourth energy-saving mode,
wherein the fourth energy-saving mode includes transmitting
user-plane data and not transmitting on access-related downlink
channels.
21. A method performed by a base node, the base node in
communication with a wireless network, the method comprising:
determining an energy-saving mode; placing the base node into the
determined energy-saving mode; and providing an indication of an
energy-saving mode status.
22. The method of claim 21, wherein the providing the indication of
the energy-saving mode status includes at least one of: setting one
or more flags in a transmitted Master Information Block (MIB),
changing a Common Pilot Channel scrambling code, sending a paging
message, or sending a dedicated message.
23. The method of claim 21, wherein the determining the
energy-saving mode includes at least one of: determining an
energy-saving mode schedule provided by a controlling radio network
controller (CRNC), or determining a low amount of activity based on
a low activity detection algorithm.
24. The method of claim 21, wherein the base node is a home Node B
(HNB) and the method further includes transitioning the base node
from the determined energy-saving mode to an active mode based, at
least in part, on a Minimization Drive Test measurement for the
HNB.
25. The method of claim 21, wherein the energy-saving mode includes
at least one of: a first energy-saving mode, wherein the first
energy-saving mode includes broadcasting only a Master Information
Block (MIB) message and System Information Block (SIB) messages
that include cell access information; a second energy-saving mode,
wherein the second energy-saving mode includes broadcasting only a
MIB message; a third energy-saving mode, wherein the third
energy-saving mode includes broadcasting only on a Common Pilot
Channel (CPICH); or a fourth energy-saving mode, wherein the fourth
energy-saving mode includes transmitting user-plane data and not
transmitting on access-related downlink channels.
26. A wireless transmit/receive unit (WTRU), the WTRU being in
communication with a wireless network, the WTRU comprising: a
receiver, the receiver configured at least to: receive a
measurement configuration from a node of the wireless network, the
measurement configuration including instructions to perform one or
more location measurements related to a location of the WTRU
relative to a remote access point cell; a processor, the processor
configured at least to: generate a first report, the first report
including a first location measurement related to the location of
the WTRU relative to the remote access point cell; and a
transmitter, the transmitter configured at least to: transmit the
first report to the node of the wireless network, the processor
being further configured to: generate up to N further reports
including up to N more location measurements related to the
location of the WTRU relative to the remote access point cell, N
indicting a maximum number of reports to be generated by the WTRU
that include the one or more location measurements related to the
location of the WTRU relative to the remote access point cell, N
being determined by the WTRU autonomously; determine that at least
one of the first location measurement or the up to N more location
measurements requires a wireless network service; and utilize the
wireless network service for the at least one of the first location
measurement or the up to N more location measurements, the
transmitter being further configured to: transmit the generated up
to N further reports to the node of the wireless network; and
transmit a vicinity indication to the node upon any one of the
first report or the up to N reports indicating that the WTRU has
satisfied a vicinity criteria for the remote access point cell.
27. The WTRU of claim 26, wherein the transmitter is further
configured to: transmit a request to the node for the wireless
network service, and the receiver being further configured to:
receive an acknowledgement for the wireless network service, the
acknowledgement including one or more parameters for the wireless
network service.
28. The WTRU of claim 26, wherein the at least one of the first
location measurement or the up to N more location measurements are
based on at least one of a Common Pilot Channel (CPICH), a
Synchronization Channel (SCH), or Broadcast Channel (Primary Common
Control Physical Channel) (BCH P-CCPCH) being transmitted by the
remote access point cell upon a command from the wireless
network.
29. The WTRU of claim 26, wherein the at least one of the first
location measurement or the up to N more location measurements are
made on a designated frequency.
30. The WTRU of claim 26, wherein the one or more parameters for
the wireless network service include parameters for at least one of
an Idle Period in Downlink (IPDL) support or a compressed mode
support.
31. The WTRU of claim 26, wherein the remote access point cell is
at least one of a pico cell or a femto cell.
32. A method performed by a wireless transmit/receive unit (WTRU),
the WTRU being in communication with a wireless network, the method
comprising: receiving a measurement configuration from a node of
the wireless network, the measurement configuration including
instructions to perform one or more location measurements related
to a location of the WTRU relative to a remote access point cell;
generating a first report, the first report including a first
location measurement related to the location of the WTRU relative
to the remote access point cell; transmitting the first report to
the node of the wireless network; generating up to N further
reports including up to N more location measurements related to the
location of the WTRU relative to the remote access point cell, N
indicting a maximum number of reports to be generated by the WTRU
that include the one or more location measurements related to the
location of the WTRU relative to the remote access point cell, N
being determined by the WTRU autonomously; determining that at
least one of the first location measurement or the up to N more
location measurements requires a wireless network service;
utilizing the wireless network service for the at least one of the
first location measurement or the up to N more location
measurements; transmitting the generated up to N further reports to
the node of the wireless network; and transmitting a vicinity
indication to the node upon any one of the first report or the up
to N reports indicating that the WTRU has satisfied a vicinity
criteria for the remote access point cell.
33. The method of claim 32, further comprising: transmitting a
request to the node for the wireless network service; and receiving
an acknowledgement for the wireless network service, the
acknowledgement including one or more parameters for the wireless
network service.
34. The method of claim 32, wherein the at least one of the first
location measurement or the up to N more location measurements are
based on at least one of: a Common Pilot Channel (CPICH), a
Synchronization Channel (SCH), or Broadcast Channel (Primary Common
Control Physical Channel) (BCH P-CCPCH) being transmitted by the
remote access point cell upon a command from the wireless
network.
35. The method of claim 32, wherein the at least one of the first
location measurement or the up to N more location measurements are
made on a designated frequency.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 61/293,432, filed Jan. 8, 2010, titled
"ENERGY-SAVING MODES FOR A BASE STATION", U.S. Provisional
Application No. 61/304,236, filed Feb. 12, 2010, titled
"ENERGY-SAVING MODES FOR A BASE STATION", U.S. Provisional
Application No. 61/304,027, filed Feb. 12, 2010, titled "METHOD AND
APPARATUS FOR REDUCING POWER CONSUMPTION OF REMOTE ACCESS POINTS",
and U.S. Provisional Application No. 61/355,687, filed Jun. 17,
2010, titled "METHOD AND APPARATUS FOR REDUCING POWER CONSUMPTION
OF REMOTE ACCESS POINTS", the contents of all four applications
being hereby incorporated by reference in their respective
entirety, for all purposes.
BACKGROUND
[0002] Cellular technology has evolved over the past decade. For
example, with the evolution of Third Generation Mobile Systems
towards High-Speed Downlink Packet Access (HSDPA) in Release 5 and
High-Speed Uplink Packet Access (HSUPA) in Release 6, higher data
rates may be obtained. This has opened to the door to new mobile
devices that offer constant connectivity to the Internet, while
continuing to offer good quality voice services. The desire to
maintain connectivity to virtual communities and the Internet, in
conjunction to the arrival of new devices capable of offering a
satisfying user experience has increased the demand on the existing
network infrastructures.
[0003] To satisfy this increasing demand, network operators have
deployed new infrastructure and/or acquired additional spectrum.
One strategy that is also being used to satisfy the increase in
traffic is to deploy smaller cells, also referred to as femto or
pico cells, in areas where the demand is higher. These femto cells
are typically located under the umbrella of a larger macro cell and
while they do not extend the coverage they increase the available
throughput in buildings and other public areas such as subways
stations, coffee shops, shopping malls and so on.
[0004] Femto cell NodeBs (i.e., NodeBs, eNB, base stations (or base
nodes), access points, and the like) have the advantage of being
low-cost and small when compared to typical macro cells NodeBs.
However, they typically serve a smaller number of user equipment
(UE) or wireless transmit/receive units (WTRUs) and are thus not
very power-efficient compared to a macro cell NodeB.
[0005] The NodeBs in a typical wireless network (for macro or femto
cells) may consume a large amount of energy. While a portion of the
energy consumed is used to carry data information, a large portion
of that energy is also used on overhead control channels. Also,
cellular networks may include devices such as base stations and
wireless transmit/receive devices (WTRU), for example, that may
consume more power than necessary for the respective operations and
functions that the devices may implement at any particular time or
in particular periods of time.
SUMMARY
[0006] This 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,
nor is it intended to be used to limit the scope of the claimed
subject matter. Furthermore, the claimed subject matter is not
limited to limitations that solve any or all disadvantages noted in
any part of this disclosure.
[0007] Embodiments contemplate that management of a base station's
and a WTRU's operations and functions may assist in the
conservation of energy (or power) for the respective base stations
and also to preserve other network resources. In a period of low
utilization, it is desirable from an operator perspective to be
more energy efficient and reduce the power consumption of any cell
site, macro or femto. Saving on energy at NodeB may be beneficial
for the Universal Mobile Telecommunications System (UMTS) and Long
Term Evolution (LTE).
[0008] Embodiments contemplate that, from an energy saving
perspective, it may be desirable to reduce the power consumption of
one or more NodeBs. Also contemplate are femto cells, which may
serve only a handful of wireless transmit/receive units (WTRUs) at
any particular time and may be idle for a long period of time.
Embodiments contemplate determinations of when to put these cells
in power-saving mode and when to bring them back to the normal
state. Also contemplated are mechanisms that may be taken by the
network (e.g., controlling radio network controller (CRNC)) to
place cells into a power saving mode. Also contemplate are
mechanisms for a WTRU to measure dormant cells.
[0009] Embodiment contemplate methods and apparatuses for reducing
power consumption of remote access points. Methods for measuring
cells in a dormant mode are also contemplated. Embodiments also
contemplate methods for determining cell vicinity and methods for
controlling a target cell for measurements in a low activity
state.
[0010] Embodiments contemplate a base node (or base station) may be
communication with a wireless network and the base node may be
configured to determine one or more energy-saving modes and may
place the base node into the determined one or more energy-saving
modes. The base node may also be configured to provide an
indication of an energy-saving mode status. The indication of the
energy-saving mode status may include at least one of: setting one
or more flags in a transmitted Master Information Block (MIB),
changing a Common Pilot Channel scrambling code, sending a paging
message, or sending a dedicated message. Embodiments contemplate
that the determining the one or more energy-saving modes may
include at least one of: determining an energy-saving mode schedule
provided by a controlling radio network controller (CRNC) or
determining a low amount of activity based on a low activity
detection algorithm.
[0011] Embodiments contemplate that one or more base stations (or
base nodes) may operate according to one or more energy-saving
modes. The energy-saving modes may involve the use of less
signalling than during normal operation, in order to save energy.
According to an exemplary first energy-saving mode, the base
station may broadcast, and in some embodiments may broadcast
exclusively, a Master Information Block (MIB) message and System
Information Block (SIB) messages that may include cell access
information. According to an exemplary second energy-saving mode,
the base station may broadcast, and in some embodiments may
broadcast exclusively, an MIB message. According to an exemplary
third energy-saving mode, the base station may broadcast, and in
some embodiments may broadcast exclusively, on a Common Pilot
Channel (CPICH). According to an exemplary fourth energy-saving
mode, the base station may transmit, and in some embodiments may
transmit exclusively, user-plane data and may not transmit on
access-related downlink channels.
[0012] Embodiments contemplate a wireless transmit/receive unit
(WTRU), may be in communication with a wireless network and that
the WTRU may be configured, at least in part, to determine that the
WTRU may be within a vicinity of a cell in a dormant mode. The WTRU
may also be configured to generate a first report that may include
one or more measurements related to a location of the WTRU. The
WTRU may also be configured to transmit the first report to the
network and to receive an indication that the WTRU is to perform
one or more measurements related to the cell. The WTRU may perform
the one or measurements related to the cell and generate a second
report that may include results of the one or more measurements
related to the cell and may transmit the second report to the
network.
[0013] Embodiments contemplate a base node that may be in
communication with a wireless network. The base node may be
configured at least in part, to provide an indicator that a
wireless transmit/receive unit (WTRU) may use to determine if the
WTRU may be within a vicinity of a cell in a dormant mode. The base
node may be configured to receive a first report that may include
one or more measurements related to a location of the WTRU. The
base node may also provide an indication to the cell based at least
in part on the first report. The indication to the cell may direct
the cell to exit the dormant mode. Embodiments contemplate that the
indication to the cell may include a WAKE-UP Common Pilot Channel
(CPICH) message. The WAKE-UP CPICH message may cause the cell to
transmit at least one of the CPICH or a Broadcast Channel (Primary
Common Control Physical Channel) (BCH P-CCPCH). The base node may
be further configured to receive an indication that the cell may
have exited the dormant mode and the base node may provide an
indication to the WTRU to generate a second report that may include
results of one or more measurements related to the cell. The based
node may also be configured to determine a handover condition and
to provide an indication to the cell based at least in part on the
handover condition. Embodiments contemplate that the indication to
the cell may cause the cell to enter an active mode. The WAKE-UP
CPICH message may cause the cell to transmit the CPICH or a
Broadcast Channel (Primary Common Control Physical Channel) (BCH
P-CCPCH) for a limited period of time.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] A more detailed understanding my be had from the following
description, given by way of example in conjunction with the
accompanying drawings wherein:
[0015] FIG. 1A is a system diagram of an example communications
system in which one or more disclosed embodiments may be
implemented;
[0016] FIG. 1B is a system diagram of an example wireless
transmit/receive unit (WTRU) that may be used within the
communications system illustrated in FIG. 1A;
[0017] FIG. 2 is 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;
[0018] FIG. 3 shows an exemplary timing diagram consistent with
embodiments where a WTRU may use location-based triggers for
dormant cell activation;
[0019] FIG. 4 shows an exemplary timing diagram consistent with
embodiments where a WTRU may use location-based triggers for
dormant cell activation determinations whether or not to proceed
with a handover to a target cell;
[0020] FIG. 5 shows an exemplary timing diagram consistent with
embodiments where a WTRU may provide a vicinity indication and may
measure a cell in low activity mode after configuration;
[0021] FIG. 6 shows an exemplary timing diagram consistent with
embodiments where the network may decide whether to proceed with a
handover to a target cell;
[0022] FIG. 7 shows an exemplary timing diagram consistent with
embodiments where the WTRU may continuously measure a cell in low
activity mode where a handover may be carried out;
[0023] FIG. 8 shows an exemplary timing diagram consistent with
embodiments where the WTRU may continuously measure a cell in low
activity mode where there may be no handover;
[0024] FIG. 9 shows a WTRU exemplary autonomous measurement and
report method consistent with embodiments; and
[0025] FIG. 10 shows an exemplary method of managing modes of a
base station consistent with embodiments.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0026] 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), the time division multiple access (TDMA), frequency
division multiple access (FDMA), orthogonal FDMA (OFDMA),
single-carrier FDMA (SC-FDMA), and the like.
[0027] As shown in FIG. 1A, the communications system 100 may
include wireless transmit/receive units (WTRUs) 102a, 102b, 102c,
102d, a radio access network (RAN) 104, a core network 106, 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.
[0028] 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, 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.
[0029] The base station 114a may be part of the RAN 104, 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.
[0030] The base stations 114a, 114b may communicate with one or
more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116,
which may be any suitable wireless communication link (e.g., radio
frequency (RF), microwave, infrared (IR), ultraviolet (UV), visible
light, etc.). The air interface 116 may be established using any
suitable radio access technology (RAT).
[0031] More specifically,, as noted, 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 104 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 116 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).
[0032] 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 116 using Long Term Evolution (LTE) and/or LTE-Advanced
(LTE-A).
[0033] 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.
[0034] 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 required to access the
Internet 110 via the core network 106.
[0035] The RAN 104 may be in communication with the core network
106, 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 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
104 and/or the core network 106 may be in direct or indirect
communication with other RANs that employ the same RAT as the RAN
104 or a different RAT. For example, in addition to being connected
to the RAN 104, which may be utilizing an E-UTRA radio technology,
the core network 106 may also be in communication with another RAN
(not shown) employing a GSM radio technology.
[0036] The core network 106 may also server 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 plan 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 104 or a different RAT.
[0037] 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 and IEEE 802 radio
technology.
[0038] 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.
[0039] 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.
[0040] 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 116. 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.
[0041] 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 116.
[0042] 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, 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.
[0043] 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 106 and/or the removable memory 132. The
non-removable memory 106 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).
[0044] 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.
[0045] 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 116 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.
[0046] 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.
[0047] FIG. 2 is a system diagram of the RAN 104 and the core
network 106 according to an embodiment. As noted above, the RAN 104
may employ a UTRA radio technology to communicate with the WTRUs
102a, 102b, and/or 102c over the air interface 116. The RAN 104 may
also be in communication with the core network 106. As shown in
FIG. 2, the RAN 104 may include Node-Bs 140a, 140b, 140c, which may
each include one or more transceivers for communicating with the
WTRUs 102a, 102b, and/or 102c over the air interface 116. The
Node-Bs 140a, 140b, 140c may each be associated with a particular
cell (not shown) within the RAN 104. The RAN 104 may also include
RNCs 142a, 142b. It will be appreciated that the RAN 104 may
include any number of Node-Bs and RNCs while remaining consistent
with an embodiment.
[0048] As shown in FIG. 2, 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.
[0049] The core network 106 shown in FIG. 2 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.
[0050] The RNC 142a in the RAN 104 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.
[0051] The RNC 142a in the RAN 104 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-enable
devices.
[0052] 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.
[0053] When referred to herein, the terminology "wireless
transmit/receive unit (WTRU)" includes but is not limited to a user
equipment (UE), a mobile station, a fixed or mobile subscriber
unit, a pager, a cellular telephone, a personal digital assistant
(PDA), a computer, or any other type of device capable of operating
in a wireless environment. Also when referred to herein, the
terminology "base station" includes but is not limited to a Node-B,
a site controller, an access point (AP), or any other type of
interfacing device capable of operating in a wireless environment.
When referred to hereafter, the terminology "network" includes a
Radio Network Controller (RNC), CRNC or Drift RNC as appropriate.
Further, the terminology "RNC" may also include a CRNC or Drift
RNC.
[0054] Examples are provided herein in terms of Universal Mobile
Telecommunications System (UMTS)/UMTS Terrestrial Radio Access
Network (UTRAN) systems. However, the concepts described herein are
equally applicable to systems based on technologies such as:
Evolved UMTS Terrestrial Radio Access Network (E-UTRAN); Long Term
Evolution (LTE); LTE-Advanced; Institute of Electrical and
Electronics Engineers (IEEE) Wireless Local Area Network (WLAN);
IEEE Worldwide Interoperability for Microwave Access (WiMax);
Wireless Broadband (WiBro); Global System for Mobile Communications
(GSM); GSM Enhanced Data Rates For GSM Evolution (EDGE) Radio
Access Network (GERAN); Code Division Multiple Access 2000
(CDMA2000); or any other wireless communications technology. Where
a specific example of a UMTS/UTRAN concept is provided, it should
be appreciated that an analogous concept in any wireless technology
may be used, mutatis mutandis. While specific UTRAN channels (such
as a Broadcast Control Channel (BCCH)) are described, analogous
channels may be used in different technologies. Where specific
types of messages (such as, for example, specific System
Information (SI) messages or Master Information Block (MIB)
messages) are described, analogous messages may be used. For
example, where a Node-B is described, a different type of base
station (such as, for example, an eNodeB, a base transceiver
station (BTS), a radio base station (RBS), an access point, or any
other type of base station) may be used. As an additional example,
wherever a Primary Scrambling Code (PSC) in a UTRAN is described, a
Physical Cell Identifier (PCI) may be used in an E-UTRAN.
[0055] Although one or more examples are provided herein in terms
of a WTRU in idle mode, the principles described below are equally
applicable to other modes, such as but not limited to URA_PCH,
CELL_PCH, and CELL_FACH states, for example.
[0056] Embodiments contemplate that when referred to herein, a base
station may be referred to as being in "dormant mode" when its
transmitter may be turned off and the base station may not be
transmitting on any channels. Also, when referred to hereafter, a
base station is referred to as being in an "energy-saving mode" or
an "energy-saving state" when it may have reduced its energy
requirements from normal operation but may not have fully turned
off its transmitter. "Energy saving state" and "energy-saving mode"
may be used interchangeably. A base station may be referred to as
"entering" or "activating" an energy-saving mode. A base station
that has the capability of operating in an energy-saving mode may
be said to "support" an energy-saving mode. Also when referred to
hereafter, a base station that "deactivates" an energy-saving state
or energy-saving mode can be considered to move from an
energy-saving state to a normal operating state.
[0057] Embodiments also contemplate that a "legacy" WTRU may be,
for example, a WTRU that may not support features that are specific
to a base station energy-saving mode. A legacy WTRU may communicate
with a base station while the base station may be in an
energy-saving mode and/or while the base station may be operating
according to normal operation. A legacy WTRU may not, however,
support energy-saving mode-specific features.
[0058] Embodiments contemplate that in UTRAN, for example, the
following System Information Block (SIB) messages may contain at
least the following information:
[0059] SIB1: which may contain information related to timer and
constants and contains a domain-specific discontinuous reception
(DRX) cycle length coefficient;
[0060] SIB3: which may contain information related to cell
reselection, cell selection rules, cell identity, and access
restrictions;
[0061] SIB4: which may contains information related to cell
identity and access restrictions, in some circumstances, a WTRU may
receive a SIB 4 message while in connected mode (e.g., not an idle
mode), if the SIB 4 message is broadcasted by a Node-B;
[0062] SIB5 and SIB5bis: which contain information related to
access rules, DRX cycles, and paging information; and
[0063] SIB6: which may contain information related to the Physical
Random Access Channel (PRACH) and the Secondary Common Control
Physical Channel (S-CCPCH), in some circumstances, a WTRU may
receive SIB 6 messages while in connected mode (e.g., not in idle
mode), if the SIB 6 message is broadcasted by a Node-B.
[0064] Embodiments contemplate that a Radio network Controller
(RNC) may send a cell configuration message to a NodeB. The cell
configuration message may include one or more information elements
(IEs) that indicate that the NodeB may, and in some embodiments
should, enter one or more energy-saving modes. The cell
configuration message may additionally include related system
information parameters. The related system information parameters
may be included in the same IEs which indicate that the NodeB may
or should enter an energy-saving mode, or may be included in one or
more different IEs. Alternatively, a cell configuration message may
include a flag indicating that the NodeB may or should enter the
energy-saving mode. Upon receiving a cell configuration message
from the RNC, the NodeB may activate an energy-saving mode
according to one or more of the received parameters. For example, a
controlling RNC may use the SYSTEM INFORMATION UPDATE REQUEST
message to inform the NodeB about new MIB/SIB transmission
requirements which may be implemented to achieve a specific energy
saving mode.
[0065] Alternatively or additionally, the NodeB may store a
definition of a configuration for the energy-saving mode. The
definition may describe, for example, which SIB messages that NodeB
may or may not transmit, and/or may be related to other system
information parameters. The RNC may send a message to the NodeB
containing an indicating information element. Upon receipt of the
information element, the NodeB may activate the energy-saving mode
according to the stored configuration for the energy-saving mode.
Additionally, the NodeB may store multiple definitions of
configurations, and the indicating information element may indicate
which definition the NodeB should use.
[0066] Additionally, an RNC may configure network nodes related to
the NodeB (for example, neighboring cells or drift RNCs (DRNCs)),
to accommodate the energy-saving mode of the NodeB and to ensure
proper operation of the network on the whole. This may include the
RNC communicating with network nodes related to the NodeB. Network
nodes that may be related to the NodeB include, for example, one or
more of the nodes (such as other NodeBs) in geographical proximity
to the NodeB. The RNC may store a list of related nodes. The RNC
may send messages to the related network nodes to configure them
appropriately. These messages may include one or more parameters
that include but are not limited to: enhanced neighbor lists (a
modified neighbor list adapted for energy saving network
operation); neighbor lists that include indicators that the NodeB
may be in an energy-saving mode; measurement control messages that
that include indicators that the NodeB may be in an energy-saving
mode (for example, a default Random Access Channel (RACH) or
enhanced-RACH (E-RACH) configuration may be utilized for WTRU
uplink measurement messages in one or more energy saving modes);
access mode parameters; reselection rules that reflect that the
NodeB may be in an energy-saving sate; and a reduced set of MIBs
and SIBs.
[0067] The related network nodes may be, for example, one or more
of the nodes in the vicinity of the cell going to energy saving
mode. The list of related network nodes may be determined by the
network.
[0068] The controlling RNC may use a new cell configuration
message, or one or a combination of existing cell configuration
messages to reconfigure neighboring nodes. The cell configuration
messages may include: SYSTEM INFORMATION UPDATE REQUEST, PHYSICAL
SHARED CHANNEL RECONFIGURATION REQUEST, or COMMON TRANSPORT CHANNEL
RECONFIGURATION REQUEST. The message may use existing modified IEs
and/or newly defined IEs to convey the energy saving mode related
cell parameters.
[0069] A NodeB may indicate that is has entered an energy-saving
mode by sending one or more messages. It may do so by, for example,
using one or more flags. The flags may be included, for example, in
one or more MIB messages. Alternatively or additionally, a WTRU may
detect whether a NodeB is an energy-saving mode by detecting the
SIB messages present or that the NodeB may be using and comparing
the detected SIB messages to a list that may include the messages
used in the energy-saving mode (e.g., this may be referred to as a
blind detection).
[0070] Alternatively or additionally, an NodeB may enter energy
saving mode autonomously based on a schedule supplied by the
controlling RNC or operation and maintenance (OAM) system, or based
on a low activity detection algorithm. Upon detection of a low
activity or no activity state, the NodeB may use a RESOURCE STATUS
INDICATION message to inform the controlling RNC that it is
entering an energy saving mode. The NodeB may use, for example, the
Resource Operational State IE and the Availability Status IE with
an appropriate cause IE or a newly defined cause such as "entering
energy saving mode."
[0071] Embodiments contemplate that upon reception of a RESOURCE
STATUS INDICATION with the "entering energy saving mode" cause set
to TRUE, the serving RNC may reconfigure the source NodeB with the
appropriate energy savings-related parameters using the existing
cell configuration messages. The controlling RNC may reconfigure
the neighboring nodes to allow for full service coverage or
appropriate mobility parameters, for example.
[0072] Alternatively or additionally, the NodeB may apply an energy
saving mode default configuration and use the RESOURCE STATUS
INDICATION with the "entering energy saving mode" cause set to TRUE
message to inform the controlling RNC of entering an energy saving
mode, and thus reducing the Iub interface signaling load. The Iub
may be an interface between the RNC and the NodeB, for example.
[0073] The NodeB may signal that it has entered an energy-saving
mode by sending one or more messages to one or more of the WTRUs
that it is serving. The one or more messages may include, for
example, a Paging Message. The Paging Message may be a Paging Type
1 message and may carry Multicast Control Channel (MCCH)
modification information. Embodiments contemplate that for an MCCH,
such as a Multimedia Broadcast Multicast Service (MBMS)
point-to-multipoint control channel, the channel/service
configuration may be changed in a NodeB while in an energy saving
mode. The WTRU may need to be informed, via a message for example,
that such a change has been or may be implemented. The one or more
messages may also include a Paging Type 2 message that may include
one or more fields describing a reason. The reason may be described
as, for example, "MIB Change." The one or more messages may include
a SYSTEM INFORMATION CHANGE INDICATION message. The SYSTEM
INFORMATION CHANGE INDICATION message may include MCCH modification
information. Alternatively or additionally, the one or more
messages may include one or more dedicated messages. Upon receiving
one or more messages indicating that the NodeB has entered the
energy-saving mode, a WTRU may re-configure itself to operate
according to the energy-saving mode. Additionally, one or more
neighboring nodes that are reconfigured to support interoperability
with the cell entering energy saving mode may use the embodiments
described herein to inform WTRUs under the neighboring nodes'
coverage that the network parameters have changed or may have
changed. Alternatively, a legacy WTRU may reselect to another base
station that is not operating in an energy-saving mode.
[0074] Embodiments contemplate instances where a legacy WTRU is in
connected mode while a base station changes to an energy-saving
mode, the base station may explicitly move the legacy WTRU to a
different base station upon receiving a connection release
indication.
[0075] Alternatively or additionally, a base station may transmit
an MIB to a legacy WTRU upon receiving a connection release
indication. The MIB may include an indication of the base station's
energy-saving mode as described previously. The legacy WTRU that
may not support energy saving cells may not be able to camp on the
cell in such an energy saving mode indicated by the base station,
and so may (perhaps in some embodiments according to the WTRU's
normal operation) search for a different base station.
Alternatively, a legacy WTRU may not know how to interpret the
information in the MIB which indicates the base station's energy
saving mode and may ignore it or declare it invalid.
[0076] Embodiments contemplate that a NodeB, upon activating an
energy-saving mode, may change the Common Pilot Channel (CPICH)
scrambling code it may be using for its cell, thereby effectively
changing the Cell Identity (Cell ID). The scrambling code may be
changed in such a way that WTRUs may be able to determine that the
base station is entering an energy-saving mode. A legacy WTRU may
not understand that the base station is entering an energy-saving
mode. Embodiments contemplate that a legacy WTRU may reselect a new
cell that may not be configured in an energy saving mode.
[0077] A base station may also use a multi-phase approach to enter
an energy-saving mode. For example, in a first phase, before the
energy-saving mode is activated, the base station may change its
cell offset values (for example, Qoffset1 and Qoffset2) to a value
such that legacy WTRUs may naturally reselect to a different cell.
In some embodiments, the base station may then pause for a time. In
a second phase, the base station may then inform one or more WTRUs
that it is entering an energy-saving mode, by using paging or any
of the other methods described previously. Again in some
embodiments, the base station may then pause for a time. In a third
and perhaps final phase, the base station may activate an
energy-saving mode. After entering an energy-saving mode, a NodeB
may broadcast a reduced set of SIBs that allow for initial access
by a WTRU capable of operating in the energy-saving mode. Also, the
reduced set of SIBs may allow initial access by a legacy WTRU,
which may be a WTRU that may not be specifically designed to
operate in the energy-saving mode, but perhaps may be able to
access a NodeB in an energy-saving mode.
[0078] Embodiments contemplate that a base station may exit an
energy-saving mode based on one or more criteria. For example, a
base station may exit an energy-saving mode based on monitored
activity in the cell. As an example, a base station may measure the
number of WTRU-originated and/or WTRU-terminated calls and compare
it to a threshold value; if the measurement is higher than the
threshold value, it may exit the energy-saving mode for the
cell.
[0079] When a base station exits an energy-saving mode, it may
notify WTRUs that it is exiting the energy-saving mode. The base
station may do so by using messages that correspond to any of the
messages described herein for the notification of entry into an
energy-saving mode. For example, the base station may set an
energy-saving flag in the MIB to indicate that the base station is
exiting the energy-saving mode.
[0080] When the base station exits an energy-saving mode, it may
send a paging message with one or more fields that indicate that
the base station has exited the energy-saving mode and/or that the
base station will begin to send SIBs according to normal operation.
The base station may then begin to broadcast SIBs per normal
operation, for example. Thus the paging message may motivate the
WTRUs to monitor the MIB and the one or more SIBs. Alternatively or
additionally, embodiments contemplate that if the MIBs/SIBs are
changing due to the base station exiting the energy-saving mode,
then the base station configuration may be changing and the paging
message may cause the WTRU to read the new information so that it
may continue to be configured in a compatible manner for
control/communication with the base station. This may allow, for
example, refreshing of normal activity parameters, such as but not
limited to: periodic location area update parameters; periodic
routing area update parameters; access mode parameters; and/or
other parameters. Alternatively, the base station may reconfigure
the cell SIBs for normal operation and let the WTRUs on the cell
operate seamlessly.
[0081] Embodiments contemplate that a cell may autonomously exit
energy saving mode based on detection of activity (for example,
incoming calls or WTRU reselections such as location updates
received or handovers) or based on a schedule supplied by a
controlling Radio Network Controller (RNC) or Operation and
Maintenance (OAM) system. The cell, while moving to normal active
state, may send an indication to the controlling RNC using a
RESOURCE STATUS INDICATION message to inform the controlling RNC of
exiting an energy saving mode. The cell may use, for example, the
Resource Operation State IE and the Availability Status IE with an
appropriate cause IE or a newly defined cause "exit energy saving
mode." Alternatively, the NodeB may use a new message over Iub
interface to inform the controlling RNC of exiting an energy saving
mode.
[0082] Upon reception of an exiting energy saving mode indication,
the RNC may reconfigure to the normal active sate specific
parameters by using the existing Node B Application Part (NBAP)
cell configuration messages, downloading the full cell
configuration, or using a new dedicated message to revert to the
normal active state configuration. Alternatively, the NodeB may
store the normal active state configuration before entering energy
saving mode, and may restore it upon leaving the energy saving
mode.
[0083] Embodiments contemplate that upon reception of an exiting
energy saving mode indication, the controlling RNC may reconfigure
one or more of the neighboring nodes to normal active state
operation to allow for normal cells inter operability. The RNC may
use the existing NBAP cell configuration messages to restore the
normal active state parameters in the one or more neighboring
nodes. The RNC may also use a new flag to indicate to the one or
more neighboring nodes that normal active state is invoked and that
normal configuration may be sent or that the one or more
neighboring nodes may restore the normal active state configuration
from their own memory.
[0084] Alternatively, embodiment contemplate that the controlling
RNC may decide to move a cell from energy saving mode to the normal
active state dynamically, based on, for example, mobility
thresholds, traffic, a specific schedule, or an OAM order. The
controlling RNC may use a flag to indicate that the energy state is
changing. The controlling RNC may also use a new dedicated NBAP
message, followed by the cell reconfiguration procedures described
above.
[0085] A WTRU may signal to a NodeB that is it is capable of
supporting operation by the NodeB according to at least one
energy-saving mode. A WTRU may indicate its capability using one or
more fields or bit flags in one or more messages. A WTRU may
indicate which types of energy-savings modes it can support. A
NodeB may use this capability information to determine when and/or
where to enter an energy-saving mode and/or which energy-saving
mode to enter. This WTRU capability information may also be
provided to an RNC, and the RNC may use the information to provide
commands to one or more NodeBs as to when to enter energy-saving
modes.
[0086] Embodiments contemplate that a NodeB may autonomously make a
determination to enter an energy-saving mode. It may send one or
more messages to the network (for example, the RNC) to indicate
that it has done so. The network (RNC) may then configure one or
more neighboring NodeBs to ensure proper operation of the network
as described herein. Alternatively, embodiments contemplate a base
station may be configured to enter an energy-saving mode when, in
some embodiments perhaps only when, it receives a command to do so
from its network (RNC).
[0087] Embodiments contemplate one or more energy-saving modes. For
example, embodiments contemplate that a NodeB may send the MIB and
SIB messages that may include cell access information, and in some
embodiments may only send the MIB and SIB messages that include
cell access information.
[0088] According to an exemplary first energy-saving mode, a NodeB
may send MIB messages and cell access information SIB messages, and
in some embodiments may only send MIB messages and cell access
information SIB messages. The MIB may contain only the schedule for
the cell access information elements. Cell access information
elements may be found in, for example, SIB5 and/or SIB5bis
messages. A WTRU may interpret the reduced MIB/SIB combination set
as an indication that the energy-saving mode is activated for that
cell. Alternatively, the MIB may contain one or more fields
indicating that the NodeB is in an energy-saving mode. The use of
the label "first energy-saving mode" (and "second energy-saving
mode", etc., disclosed infra) is done for the purpose of
illustration and does not imply any required order, prerequisite,
dependency, and/or relative level of importance or utility among
the disclosed energy-saving modes.
[0089] When a NodeB sends only MIB messages and cell access
information SIB messages, this may be sufficient information for
other WTRUs to establish access to the NodeB. However, other
information that may typically be included in the SIB messages
(which are not being broadcasted) may be needed by a WTRU. To
obtain this other information, the WTRU may send a Location Update
message to the NodeB. The WTRU may send the Location Update message
using the parameters received in the SIB5 and/or SIB5bis messages.
In an instance where the WTRU is in idle mode prior to sending the
Location Update message, the WTRU may first send an RRC Connection
Request message to the base station. The RRC Connection Request
message may indicate an establishment cause to the network. For
example, the establishment cause may indicate that the WTRU needs
to reselect to a cell in energy-saving state. Also by way of
example, the establishment cause may indicate a "Cell Reselection
Request" or "System Information Request", among others.
[0090] Embodiments contemplate that in response to the Location
Update request message, the NodeB may send a Location Update
Acknowledge message to the WTRU. The Location Update Acknowledge
message may include the remainder of information that would
typically be included in the SIB messages according to normal
operation, for example. Alternatively, the Location Update
Acknowledge message may indicate that the WTRU should use a default
system information configuration. The default system information
configuration may be pre-configured, or may be sent by the network
to the WTRU via one or more other cells.
[0091] In an instance where the WTRU uses discontinuous reception
(DRX) in idle mode, the WTRU may need a "CN domain-specific DRX
cycle length coefficient" parameter that is broadcast in SIB1, for
example. This parameter may be used to calculate the DRX cycle
length. In such an instance, the base station may additionally
broadcast SIB1 in addition to SIB5 and/or SIB5bis. An SIB1 message
transmitted by the NodeB may include some or all of the typical
SIB1 field, or may include only the "CN domain-specific DRX cycle
length coefficient" field. Alternatively, a different SIB message
may be used to contain the "CN domain-specific DRX cycle length
coefficient" field. This different SIB message may be, for example,
"SIB20," or it may be a different message.
[0092] Further, a SIB message may be used to broadcast only the
information necessary to configure the RACH (Random Access Channel)
and the Forward Access Channel (FACH) and to allow for a WTRU to
send an RRC Connection Request message. This SIB message may be,
for example, "SIB 5" and/or "SIB 6", or a different message. It may
contain, for example, a "Physical Random Access Channel (PRACH)
system information list" field and/or a "Secondary Common Control
Physical Channel (S-CCPCH) system information" field.
[0093] According to an exemplary second energy-saving mode, a NodeB
may transmit the MIB, and in some embodiments may only transmit the
MIB. This may be used, for example, where a target cell may
broadcast only the MIB and where access information requested for
cell reselection may be broadcast to WTRUs in the source cell.
[0094] A NodeB, when in energy-saving mode, may transmit only the
MIB and may use a default configuration for cell system
information. In conjunction with information provided by another
NodeB (which may not be in an energy-saving mode), a WTRU may
reselect and access the NodeB that is in the energy-saving mode.
Access information required for cell reselection may be provided to
the WTRU in the source cell. This may be done according to one or
any combination of the following approaches, as well as via other
approaches not listed herein.
[0095] Embodiments contemplate that default cell system information
may be used. When a target base station is in energy-saving mode,
it may use a special configuration, in addition to dedicated cell
information. The default configuration may depend on the
capabilities of the NodeB, and/or may be defined according to a
standard, for example.
[0096] Embodiments contemplate that the information may be
pre-configured per one or more energy-saving neighboring cells.
This information may include the minimum required information for
cell access, or may include the entire system information.
[0097] Embodiments contemplate that a WTRU may receive a neighbor
cell list which contains energy-saving mode parameters for
neighboring cells. The neighbor cell list may contain information
related to the energy-saving state of one or more neighboring
NodeBs (if applicable), and/or may contain SIB information for the
one or more neighboring NodeBs (if applicable).
[0098] Embodiment contemplate that a WTRU may receive, in one or
more dedicated messages, information for energy-saving mode
parameters and/or SIB information related to a neighboring NodeBs.
The WTRU may send a query for this information to a NodeB and/or
RNC, and this information may be received in a response
message.
[0099] To obtain system information that may not be broadcast by
the target NodeB and that cannot be acquired in a source cell,
and/or is not in a default system information configuration, a WTRU
may send a Location Update message to the NodeB and/or the RNC
associated with the NodeB, by using default access parameters
and/or parameters received in the source cell. Alternatively, the
WTRU may send an RRC Connection Request message or other RRC
message. The RRC Connection Request message may indicate an
establishment cause to the network. For example, the establishment
cause may indicate that the WTRU needs to reselect to a cell in an
energy-saving state.
[0100] The NodeB and/or RNC may respond to the RRC Connection
Request or other RRC message by sending a Location Update
Acknowledge message to the WTRU. The Location Update Acknowledge
message may contain information that may be required by the WTRU to
access the target NodeB in an idle or connected mode, for example.
In an instance where an entire system information configuration was
made available to the WTRU in the previous cell and/or the new base
station is not an energy-saving cell, the message may be a Location
Update Acknowledge message that has contents per normal
operation.
[0101] Alternatively, the NodeB and/or RNC may respond to the RRC
Connection Request or other RRC message by sending the WTRU at
least one paging message. The paging message may be a Paging Type 1
message carrying Broadcast Channel (BCCH) modification information.
The paging message may also be a Paging Type 2 message with new
information, such as a system information change indicator. The
NodeB may broadcast the MIB and/or SIBs for some period of time,
and then return to an energy-saving mode. SIB3, SIB5, and SIB7 may
not be schedule in the MIB that is broadcast. So that the WTRU will
not determine that the Node B is barred, or to avoid such a
determination, the MIB may contain a flag indicating that the NodeB
is in an energy-saving mode.
[0102] Alternatively, the NodeB and/or RNC may respond to the RRC
Connection Request or other RRC message according to the following:
Before the base station enters an energy-saving mode, it may send a
message to its RNC to indicate that it is doing so. The RNC may
then indicate to the WTRU (via one or more other base stations)
which neighboring base stations are in an energy-saving mode. When
a base station is leaving an energy-saving mode, it may send
another message to the RNC, indicating that it is doing so. The RNC
may then update data that it is storing regarding the base
station's state, and may reconfigure the neighboring base station
for normal operation. One or more messages may be used to indicate
whether one or more neighboring base stations are in an
energy-saving mode and which are not using the procedures described
previously. The messages may be include, for example, one or more
measurement control messages used for controlling WTRUs in cell_DCH
state. Alternatively or additionally, the messages may include
SIB11 and/or SIB12 messages.
[0103] Upon receiving the information that indicates which
neighboring base stations are in an energy-saving mode and which
are not, the WTRU may perform a cell reselection procedure to
reselect to a cell that is in an energy-saving mode.
[0104] Embodiments contemplate an exemplary third energy-saving
mode in which a NodeB may broadcast the Common Pilot Channel
(CPICH) and/or Synchronization Channels (SCH), and in some
embodiments may only broadcast the Common Pilot Channel (CPICH)
and/or Synchronization Channels (SCH). In doing so, the NodeB may
not transmit the MIB and SIBs as per normal operation. The NodeB
specific energy saving mode configuration and neighboring nodes may
be achieved using the one or more of the procedures described
previously.
[0105] Embodiments contemplate that access information required for
cell reselection, or at least minimum access information, may be
provided to the WTRU in the source cell. This may be done according
to one or any combination of the following approaches, as well as
via other approaches not listed herein.
[0106] Embodiments contemplate that default cell system information
may be used. The default cell system information may include a
subset of channels such that a WTRU may make determinations for
mobility or modulation purposes. By way of example, a default set
of information may be standardized or signaled by a RRC,
predetermined, or otherwise known to the WTRU and the NodeB so that
the system can operate with out the customary MIBs and SIBs. When a
target base station is in energy-saving mode, it may use a special
configuration, in addition to dedicated cell information. The
default configuration may depend on the capabilities of the NodeB,
and/or may be defined according to a standard, for example.
[0107] Embodiments contemplate that the information may be
pre-configured per energy-saving neighboring cell. This information
may include the minimum required information for cell access, or
may include the entire system information.
[0108] Embodiments contemplate that a WTRU may receive a neighbor
cell list which contains energy-saving parameters for neighboring
cells. The neighbor cell list may contain information related to
the energy-saving mode of one or more neighboring NodeBs (if
applicable), and/or may contain SIB information for the one or more
neighboring NodeBs (if applicable).
[0109] Embodiments contemplate that a WTRU may receive, in one or
more dedicated messages, information for energy-saving mode
parameters and/or SIB information related to one or more
neighboring NodeBs. The WTRU may send a query for this information
to a NodeB and/or RNC, and this information may be received in a
response message.
[0110] To obtain system information that may not be broadcast by
the target NodeB and that cannot be acquired in a source cell,
and/or is not in a default system information configuration, a WTRU
may send a Location Update message to the NodeB and/or the RNC
associated with the NodeB, by using default access parameters
and/or parameters received in the source cell. Alternatively, the
WTRU may send an RRC Connection Request message or other RRC
message. The RRC Connection Request message may indicate an
establishment cause to the network. The RRC Connection Request
message may indicate an establishment cause to the network,
indicating that the WTRU may need to reselect to a cell in an
energy-saving mode.
[0111] The NodeB and/or RNC may respond to the RRC Connection
Request or other RRC message by sending a Location Update
Acknowledge message to the WTRU. The Location Update Acknowledge
message may contain information required by the WTRU to access the
target NodeB in an idle or connected mode. In an instance where an
entire system information configuration was made available to the
WTRU in the previous cell and/or the new base station is not an
energy-saving cell, the message may be a Location Update
Acknowledge message that has contents per normal operation.
[0112] Alternatively, the NodeB and/or RNC may respond to the RRC
Connection Request or other RRC message by sending the WTRU a
paging message. The paging message may include a system information
change indicator. The NodeB may broadcast for a time the MIB and
SIBs, and then return to an energy-saving mode. In an instance
where a WTRU is in a cell_FACH state, the NodeB may send a SYSTEM
INFORMATION CHANGE INDICATION message to the WTRU.
[0113] Under normal operation, when a WTRU does not receive a MIB
from a NodeB, the WTRU may interpret the NodeB as being barred. To
prevent this from occurring, the NodeB may include in CPICH frames
an indicator that indicates that that the NodeB is in an
energy-saving mode. A WTRU may receive a CPICH frame that may
include the indicator and process the indicator. Based on the
indicator, the WTRU may determine that the NodeB is in an
energy-saving mode. Additionally, because the WTRU may determine
that the NodeB is in an energy-saving mode, the WTRU may make a
determination to not try to read the MIB (as not MIB is being
transmitted). Alternatively or additionally, the source NodeB may
transmit one or more messages to the WTRU, the one or more messages
including one or more fields that indicate that the target NodeB is
in an energy-saving mode. Based on the one or more messages, the
WTRU may determine that the target NodeB is in an energy-saving
module and know that the target NodeB is not barred.
[0114] Embodiments contemplate that, in addition to or as an
alternative to the approaches described above, an exemplary fourth
energy-saving mode may include that the NodeB may transmit on data
channels, and in some embodiments may only transmit on data
channels, and may not transmit on access-related downlink channels
(such as, for example, the Acknowledge Indication Channel (AICH)
and/or the BCCH). This may be achieved using any of the procedures
described previously. This energy-saving mode may be referred to as
a "traffic-only" energy-saving mode. The NodeB may continue to
transmit only the CPICH, and/or in some embodiments the SCH, for
measurement purposes. The NodeB may communicate only with WTRUs
that are in connected mode. According to this energy-saving mode, a
WTRU may not be able to camp on the NodeB using normal reselection
methods. Alternatively or additionally, this energy-saving mode may
provide signals that may be required for a WTRU to measure and
report to one or more networks. Embodiments contemplate that this
energy-saving mode may be enabled temporarily, perhaps for some
period of time (predetermined or otherwise), to allow one or more
WTRUs to perform measurements. The NodeB may leave the
energy-saving mode and enter a dormant mode upon the end of the
period of time or upon receipt of a message from the RNC or other
controlling node to enter a dormant mode.
[0115] it should be understood that any of the embodiments
described herein directed to the function or capability of the WTRU
and/or a base node (or base station) may be implemented by one or
more processors configured to perform the disclosed function or
capability. For example, the processor 118 described with regard to
FIG. 1B may be configured to perform some or all of the various
WTRU functions and capabilities disclosed herein, in whole or in
part. Also by way of example, a processor included in an RNC or
Node-B described with regard to FIG. 2 may be configured to perform
some or all of the various base node functions and capabilities
disclosed herein, in whole or in part.
[0116] A WTRU may camp on a cell that is operating according to
normal operation. When the WTRU moves to connected mode, the source
NodeB may handover the WTRU to the cell that is operating in the
traffic-only energy-saving mode.
[0117] Embodiments contemplate that traffic-only NodeBs may be
advertised to WTRUs using Measurement Control messages. The
Measurement Control messages may be sent to WTRUs in a DCH
Connected state. Traffic-only NodeBs may be included is part of a
soft handover active set. Some or all of the operations involved in
normal DCH Connected State operations may be applicable to
traffic-only NodeBs.
[0118] A WTRU may participate in a call and/or packet data
transmission on a traffic-only NodeB. Embodiments contemplate that
at the end of a call/packet data transmission, the WTRU may be
handed over to a normal cell in the same network, or to a different
radio access technology, based on existing procedures.
Alternatively or additionally, the NodeB and/or RNC may send the
WTRU a connection release message. In response to the connection
release message, the WTRU may be moved to a FACH state, and may be
handed over to a NodeB in a normal active state. By way of example,
a FACH is the Forward Access Channel, which may be carried by the
Secondary CCPCH. Also by way of example the PCH (Paging Channel),
may also be carried by the Secondary CCPCH. The FACH may be used to
answer the RACH (Random Access Channel) on an uplink (UL)
channel.
[0119] Embodiments contemplate energy saving modes for micro-cell
base stations. Although the examples provided previously are with
respect to macro NodeBs, the principles described are equally
applicable to Home NodeBs (HNBs) and other micro-cell base
stations.
[0120] A HNB may be required to transmit the MIB and SIB3/4. A home
eNodeB (HeNB) may also be required to transmit the MIB and SIB1.
These requirements are in place to address at least some issues
that may arise due to the use of a PSC (at HNBs) and a PCI (at
HeNBs). For example, for Primary Synchronization Code (PSC), there
may be a limited number of PSC codes, which may cause issues when
there are many HNBs since the number of unique codes may be
limited. Similar issues may also exist for Physical Cell Identity
(PCI) in LTE. RRC functions may be located in the HNB and the
interface with an HNB management system (HMS) entity may control
configuration. Embodiments contemplate that the controlling RNC may
be the HNB.
[0121] A WTRU may receive and store system information and cell
access parameters related to a HNB. The WTRU may store the
parameters as part of fingerprint-type information the WTRU stores
from the HNB. The WTRU may include the information in an
information element that may be used when the HNB is in
energy-saving mode.
[0122] In an instance where a PSC or PCI is changed or reconfigured
(due to a reboot, power cycle, or other cause, for example), a WTRU
may automatically reacquire additional system information blocks.
Alternatively or additionally, system parameters may be
maintained/stored by a HNB-GW and/or a HNB Management System (HMS).
When the PSC or PCI is changed, the maintained/stored system
parameters may be used for HNB configuration.
[0123] The energy consumption of an HNB as a user/watts ratio may
be higher, perhaps significantly higher, than the ratio for a macro
cell, due to the reduced number of users served by a femto cell (or
HNB). However an HNB may be considered customer premises equipment
(CPE), so the consumed energy may be billed to the customer. The
following may address the HNB energy savings modes and describe a
service subscription concept for a HNB owner. For purpose of
efficient description, the term HNB as used herein may be
understood to include a femto cell. Also, the term femto cell as
used herein may be understood to include an HNB.
[0124] Embodiments contemplate a new Minimization of Drive Test
(MDT) measurement type that may allow for WTRU location
determination in relation to a HNB. This measurement may be set up
by the macro layer network or a HNB (for example, in a campus
network scenario) in the vicinity of a HNB based on the WTRU
mobility history that the network may have stored. This measurement
setup may be carried by a dedicated RRC Measurement Control message
for UMTS or may be autonomously established by the WTRU based on
information carried in MIB or other SIBs. This measurement report
may be a one-time report or a periodic report, for example.
[0125] Alternatively, the WTRU may begin autonomously sending this
report when approaching a HNB from a stored white list with a valid
fingerprint, for example. Alternatively or additionally, the
measurement report may be triggered manually by the user as a
one-time report.
[0126] Embodiments contemplate that this measurement request/report
message, hereinafter referred to as MDT HNB, may contain one, all,
or any combination of the following parameters: Trigger type (for
example, Energy saving HNB), Configuration parameters (for example,
Energy Saving Mode or Active Normal State), or Measurement
parameters. Measurement parameters may include, for example, HNB
(CSG ID, PLMN, RAT, or Frequency), Location (GPS or other type of
location information), Time Stamp (time report), Delay (time to
leave or enter energy saving mode), and/or Radio Environment
measurements.
[0127] Embodiments contemplate that the network may use the MDT
HNB-related report to move a HNB in energy saving mode into a
normal active state. The measurement report may have at least the
Configuration parameter Active Normal State flag set. Additionally,
this action may be based on a delay time set in the report.
[0128] Alternatively, the report may be sent with at least the
configuration parameter Energy Saving Mode flag set. This may
include sending the HNB with these measurements to Energy Saving
Mode. This report may be triggered manually by the subscriber, for
example. Upon reception of this message, the network may check the
membership of the WTRU with this Closed Subscriber Group
identification (CSG ID), check for any other WTRUs served by the
HNB and, if all conditions for entering energy saving mode are met,
reconfigure the HNB for energy saving mode. This action may be
based on a delay time set in the report. For example, HNB's may
have CSGs which may limit which WTRUs can use the HNB.
[0129] Upon receiving the MDT HNB report type, the network may
update the energy status bits in the HMS database and core network
and may perform a HNB state change according to the measurements,
delay time, and Energy Saving Mode/Active Normal State flags. The
network may use the HMS provisioning procedures or a new message
containing the energy savings mode parameters. The HNB may
enter/exit Energy Saving Mode based on the HMS orders.
[0130] Embodiments contemplate that if the MDT network node entity
may be used as an end point for the MDT type of reports, a new
interface between MDT node and HMS entity may be required to
exchange the energy savings-related orders and HNB state
synchronization. In addition, the HNB neighboring nodes may be
informed of the HNB energy state, perhaps to allow for
inter-operability regarding MDT HNB measurements triggers. This
feature may be a network subscription service. Thus, WTRUs
subscribed to this feature may be allowed to use the feature for
energy savings operations for their own HNB cells.
[0131] Embodiments contemplate that the new measurement type
capability may be signaled through a new capability bit or by
release number of the WTRU. This capability signaling may be
conditioned by service subscription. Alternatively, the network may
signal this capability through a new bit in the MIB or other system
information element or in a dedicated RRC message such as
Measurement Control or any other RRC message, for example.
[0132] A HNB that may be capable of energy savings may signal this
capability through a capability bit or through a release number
during its registration procedure with the network. Upon detection
of this capability, the HMS may configure the HNB for energy saving
operation or may disable the feature if not supported.
Alternatively, the energy savings feature, if supported, may be
disabled/enabled based on a service subscription basis.
[0133] A new bit may be added in the HMS (HNB Management System)
database to maintain the Energy Saving State: Energy Saving
Mode/Active Normal State. This bit may be replicated in the core
network for the CSG ID and cell identity and synchronized with the
HMS database. This may allow the HMS to perform the energy saving
mode operations based on mobility in a dynamic fashion.
[0134] In combination with one or any of the energy-saving modes
and/or other features described above, different statistical
techniques may be used to determine when a NodeB should enter an
energy-saving mode. Operation and Maintenance (OAM) statistics, for
example, may be used. OAM statistics, in some instances, may be
non-dynamic and/or include semi-static decision-making techniques.
OAM statistics may be long-term collected statistics. Alternatively
or additionally, Transport Network Layer (TNL) statistics may be
used. TNL statistics are based on transport network activity, and
may include statistics and interfaces for energy savings decisions.
Alternatively or additionally, Radio Network Layer (RNL) statistics
may be used. RNL statistics may be based on RNC statistics. In some
instances, RNL statistics may be considered a dynamic for of
statistics.
[0135] FIG. 10 illustrates an exemplary embodiment of a base node
determining and entering one or more energy-saving modes. At 1002,
a base node may determine an energy saving mode or one or more
energy-saving modes. At 1004, the base node may be placed into the
determined energy saving mode or one or more energy-saving modes.
At 1006, the base node may provide an indication of an
energy-saving mode status. At 1008, the base node may transition
from the determined energy saving mode or one or more energy-saving
modes to an active mode.
[0136] Embodiments contemplate that a cell may be said to be in a
dormant mode when it may not be transmitting any signals over the
air. A cell in dormant mode may not be detected, or may not be
detectable, by a WTRU. Further, a cell may be said to be in low
activity mode when it is transmitting only a subset of the control
channels, for instance a reference signal, common pilot channel
(CPICH), a synchronization signal such as a synchronization channel
(SCH) and, in some embodiments, the broadcast channel (BCH),
possibly, with extended periods of discontinuous transmission
(DTX).
[0137] When referred to hereafter, a target cell may be a regular
NodeB, covering a macro, or more likely a femto or pico cell. The
target cell may be assumed to be in an energy saving mode (either
dormant or in low activity mode). When referred to herein, the
(CPICH) refers to a reference channel that may be used for
measurement purposes in other technologies.
[0138] Embodiments contemplate that the reference pilot channel
(e.g. CPICH) of the target cell may broadcast/activate the SCH
(both primary and secondary channels) that may help the WTRU
perform one or more required measurements properly. Thus, when
referring to CPICH herein, it may be understood that it may refer
to any combination of reference signals required for
measurements.
[0139] Embodiments contemplate one or more protocol
aspects/framework for measuring cells in dormant mode. For example,
to FIG. 3 shows a timing diagram of an exemplary embodiment in
which the WTRU may use location-based triggers for dormant cell
activation.
[0140] Embodiments contemplate that the WTRU may be configured with
measurements that may be triggered once the WTRU is in the vicinity
of a target dormant cell (at 301). By way of example, being in the
vicinity of a target dormant cell may mean or include the location
where a WTRU would be served by the target dormant cell if the cell
were not dormant or a location where the WTRU would be measuring
the target dormant cell if the cell were not dormant. The WTRU may
be configured to signal the network that it is in the vicinity of
the dormant cell using RRC signaling once the WTRU may detect that
it is in the vicinity of the dormant cell. For example, the WTRU
may use a MEASUREMENT REPORT message that may carry the
measurements that caused the trigger (at 302).
[0141] Embodiment described herein may be described in terms of one
dormant cell, but it may be understood that the embodiments are
equally applicable to one or more dormant cells. More specifically,
if more than one cell may be dormant in the vicinity of the WTRU
and in the scenario where the network may not know the exact
location of the WTRU, more than one dormant cell may be reported
and may be woken up using any of the embodiments described
herein.
[0142] The network may be configured to wake up the dormant target
cell. This may be accomplished, for example, by signaling a wake up
signal to the dormant cell via Iur/Iub or S1/X2 interfaces in the
LTE scenario. The wake up signal may indicate that the cell needs
to power up the reference channel(s) and the other channels that
may be necessary for the WTRU measurement. Regarding UMTS, this may
correspond to the CPICH and/or, in some embodiments, the SCH. The
CPICH for a WTRU to measure is shown in a WAKE UP CPICH message (at
303). In response to this wake up message, the target cell may be
configured to send a confirmation message to the RNC once its CPICH
has been activated (e.g., WAKE UP CPICH Confirm) (at 304). The WAKE
UP CPICH and WAKE UP CPICH Confirm messages may be new messages
and/or existing messages such as, for example, the CELL
RECONFIGURATION MESSAGE carrying the dormant mode Indicator
Information Element (IE).
[0143] Embodiments contemplate that once the target cell starts
transmitting its CPICH or reference signal, the network may
reconfigure the WTRU to measure this cell (at 305). This may be
achieved, for example, by sending a new MEASUREMENT CONTROL message
to the WTRU requesting for measuring a particular cell on a
particular frequency. If necessary, the network may also provide
the necessary measurement gap for inter-frequency (or inter-RAT)
measurement. Optionally, the network may also provide any
parameters that allow measuring that cell (e.g., extended DTX or
dormant cell parameters) along with the MEASUREMENT CONTROL
message. The WTRU may further be configured to send the MEASUREMENT
REPORT with the requested measurement to the RNC using RRC
signaling (at 306). Then, the RNC may be configured to make a
handover decision (at 307).
[0144] Alternatively or additionally, the target cell upon
reception of a WAKE UP CPICH order may also start broadcasting the
BCH transport channel on the primary common control physical
channel (P-CCPCH). This may occur, for example, in case the system
frame number (SFN) is requested in the WTRU Measurement control (at
305) of the previously described procedure or for LTE systems
wherein the WTRU may need some information from the master
information block/system information block (MIB/SIB) to operate
properly.
[0145] In some embodiments, only the MIB may be broadcasted and
without the other SIBs, or alternatively, only the SIB1 and/or SIB3
may be broadcasted in combination with MIB. Alternatively, all SIBs
may be activated or only the ones with relevant information.
[0146] If not activated during the measurement period (at 305-306),
the BCH transport channel on the P-CCPCH physical channel may be
activated upon activation of the target cell (moving to ACTIVE
STATE).
[0147] In order to avoid other WTRUs in idle mode camping on this
cell, the target cell may be barred or reserved during the cell
measurement allowed period or even once fully activated.
Embodiments contemplate that a fully activated cell may bar other
WTRUs from camping on this cell. For example, once the connected
mode WTRU moves out of the coverage of this cell the network may
again deactivate this particular cell without having to move the
idle mode WTRUs out of this cell. The cell barring may be
implemented using existing procedures or alternatively, a new
indicator on the BCH may indicate that the cell may be only active
for measurements purposes and WTRUs may not camp on it.
[0148] Assuming that the network makes the decision to proceed with
the handover, the network may, if necessary, indicate to the target
cell that it needs to fully wake up to an active state. This may be
accomplished by sending an ACTIVE STATE signal to the target cell
over Iur/Iub (at 308). The target cell may then respond when it is
fully activated with an ACTIVE STATE Confirm message (at 309).
[0149] Once the target cell is fully activated, the network may
proceed with the handover procedure (at 310). If the cell barred
during step 305-306, upon moving to ACTIVE STATE, the barring
option may be turned off allowing for normal operation access.
[0150] FIG. 4 shows another exemplary timing diagram where the WTRU
may use location-based triggers for dormant cell activation and the
network may make the decision to not proceed with a handover to the
target cell (at 407). In this case, the network may indicate the
target cell to turn off its reference channels (CPICH, SCH and
possibly BCH (P-CCPCH) if broadcasted), for example, by sending a
SLEEP CPICH signal via Iur/Iub effectively sending the cell to a
dormant state (at 408). The target cell may, in some embodiments,
respond with a SLEEP CPICH Confirm to indicate to the network that
is now in a dormant state (at 409). As for the WAKE UP CPICH
message, this SLEEP CPICH message may be a new message or may also
be an existing message such as, for example, the CELL
RECONFIGURATION MESSAGE IE carrying the Dormant mode Indicator IE.
Elements 401-406 in FIG. 4 are similar to elements 301-306
described with reference to FIG. 3.
[0151] The elements described previously and otherwise herein may
be performed in any combination or order and some elements may not
be executed depending on the particular implementation of the
embodiments.
[0152] Alternatively, the network may fully wake up the cell upon
indication of the WTRU's vicinity instead of just wake up the
CPICH. The network may configure the cell in normal operation, as
described previously. The cell may be, in some embodiments, barred
or reserved, and once a handover decision is performed, the network
may setup the radio link resources associated with the cell and
perform the handover.
[0153] Embodiments contemplate that the previously described
elements may also be applicable to a scenario where the cell is in
a low activity mode instead of a dormant mode. More specifically,
once the WTRU triggers a report, the network may move the cell out
of low activity mode and may optionally wake up the CPICH or
alternatively may fully wake up the cell.
[0154] FIG. 5 shows a timing diagram of an exemplary embodiment
where the WTRU may provide a vicinity indication and may measures a
cell in low activity mode after configuration.
[0155] Embodiments contemplate that the WTRU may be configured with
measurements that may be triggered once the WTRU is in the vicinity
of a target cell in low activity mode (at 501). The WTRU is not
configured to measure the cell in low activity mode. Once the WTRU
detects that it is in the vicinity of the target cell, it indicates
it to the network via RRC signaling, for example using a
MEASUREMENT REPORT message optionally carrying the measurements
that caused the trigger (at 502).
[0156] the network may be configured to request the WTRU to measure
the target cell in a low activity mode. The WTRU may receive a
MEASUREMENT CONTROL message providing the measurement information
(at 503). The WTRU may be configured to perform the measurement and
reports the result to the network, for example via a MEASUREMENT
REPORT (at 504).
[0157] The network may be configured to make the decision to
perform a handover (at 505). In this case, the network signals to
the target cell in low activity mode to change to normal mode of
operations, for example by sending an ACTIVE STATE message via
Iub/Iur signaling (at 506). The target cell may then respond to the
RNC with an ACTIVE STATE Confirm message after it has resumed to
normal mode of operations (at 507). After the target cell is in
normal mode of operations, the handover procedure may be carried
out (at 508).
[0158] FIG. 6 shows an exemplary timing diagram where the network
decides to not proceed with a handover to the target cell (at 605).
Because the target cell may already be in low activity mode, no
further actions may be required. Elements 601-604 of FIG. 6 are
similar to elements 501-504 described with reference to FIG. 5.
[0159] Embodiments contemplate that the WTRU may be configured to
measure the target cell which may be in a low activity mode. FIG. 7
shows a timing diagram of an exemplary embodiment where the WTRU
may continuously measure a cell in low activity mode where a
handover is carried out.
[0160] Embodiments contemplate that the WTRU may be configured to
receive a MEASUREMENT CONTROL message by the network via RRC
signaling (at 701). This measurement control may carry specific
information regarding the target cell to measure, including
potential extended DTX information. The WTRU may trigger and send a
MEASUREMENT REPORT when appropriate carrying the measurement
related to the target cell (at 702). The network may make a
handover decision (at 703).
[0161] Alternatively or additionally, the target cell may broadcast
the Broadcast Channel Primary Common Control Physical channel (BCH
(P-CCPCH)) and organize the DTX cycles based on the MIB and
required SIBs. In order to avoid the WTRUs camping on the cell
during the low activity state, the network may keep the cell barred
or reserved and return it to normal service only when moving to
ACTIVE STATE. Alternatively, the target cell may be kept barred or
reserved even once fully activated.
[0162] In some embodiments, only the MIB may be broadcasted without
the other SIBs, or alternatively, only the SIB1 and/or SIB3 may be
broadcasted in combination with MIB. Alternatively, all SIBs may be
activated or perhaps only the ones with relevant information.
[0163] The BCH (P-CCPCH) channel may be required to read the System
Frame Number (SFN), which may be useful, and in some embodiments
perhaps necessary, to understand the frame structure of the DL
signal. The WTRU may be configured to read SFN for the target cell
but, in some embodiments, may not be capable of decoding it due to
the DTX cycles or P-CCPCH channel not being broadcasted.
Embodiments contemplate allowing the WTRU to report the measured
cell required quantity (CPICH RSCP or Ec/No) without SFN or with a
dummy value, and/or setting a flag in the measurement report
meaning "SFN not readable".
[0164] If the BCH (P-CCPCH) channel is not broadcasted in low
activity mode, then it may be activated (e.g. at 704 described
below), and the WTRU may perform a blind handover (perhaps with SFN
reading at the handover time).
[0165] Embodiments contemplate that where the network may decide to
proceed with the handover, the RNC may signal the target cell to go
into a full active state for example by sending a ACTIVE STATE
message via Iub/Iur (at 704). Alternatively or additionally, the
target cell may transmit a confirmation message back to the RNC
when the full active state has been reached, for example by sending
an ACTIVE STATE Confirm message (at 705). Once the target cell may
be fully activated, the network may proceed with the handover
procedure (at 706).
[0166] FIG. 8 shows an exemplary timing diagram where the WTRU may
continuously measure a cell in low activity mode where there is not
handover (at 803). Because the target cell is already in low
activity mode, no further actions are required. Elements 801 and
803 in FIG. 8 are similar to elements 701 and 702 described with
regard to FIG. 7.
[0167] Embodiments contemplate that the WTRU location information
used to determining cell vicinity may be useful elements to the
successful application of the embodiments described herein.
Embodiments contemplate methods for obtaining location information
using one or more WTRU measurements.
[0168] Embodiments contemplate a number of measurements that may be
performed by the WTRU to assist in acquiring the location
information at one or more different levels of estimation
precision. The measurements may range from radio environment
measurements to dedicated position measurements. More specifically,
the measurements may include: receive power of downlink pilot tone
(the downlink pilot is carried on CPICH channel for WCDMA and
carried on common reference signal (CRS) for LTE); signal quality
parameters, such as Signal to Interference Ratio (SIR) or Energy
per Chip/Noise (Ec/No, which may be a measure of the signal to
noise ratio of the received signal) of a common channel; channel
condition parameters such path loss calculated by power attenuation
between the transmitted and received signals; and location
information obtained by the IPDL measurement procedures, which is a
location service achieved by time difference measurement from Idle
Period in Down Link (IPDL).
[0169] Based on one or more of the previously described
measurements performed with respect to multiple non-collocated
neighbor NodeBs, the WTRU, or RNC, may have the capability of
providing appropriate estimation of WTRU locations, for example,
pattern matching technologies.
[0170] Embodiments contemplate that the WTRU may be equipped with a
globe positioning system (GPS), and as such, accurate position
information may be available from the WTRU. However, the GPS
negatively may impact the power consumption impact of a WTRU
battery. As a result, embodiments contemplate that frequent GPS
measurement may be avoided if it is possible for the purpose of
saving batter power.
[0171] Embodiments contemplate that one or more types of
measurements, such as GPS measurements in the WTRU, may be
triggered by the network. The network may determine that a WTRU is
in a geographical area where energy saving mechanisms may be taking
place. For example, cells in the area may be dormant or in low
activity state. Alternatively, this may be determined autonomously
by the WTRU.
[0172] The WTRU may also store the fingerprint information that
maps the measured radio environment parameters to the WTRU's
geographic position relative to the NodeBs from which the
measurement is performed. For example, this fingerprint map may be
obtained through historical information recorded by the WTRU and/or
may be preconfigured downlink transmission from the network. Using
this fingerprint map, it may also possible for the WTRU to know the
distribution of the remote access points.
[0173] Embodiments contemplate that a Minimization of Driving Test
(MDT) feature may provide the WTRU the capability of logging and
transmitting to the network important measurement information, for
example in an effort to reduce the deployment and operation cost
for the cellular operators. As the specified measurement parameters
in this feature may already include the required location
information, this feature may be a convenient way to achieve power
savings. WTRU measurement and reporting methods may be based on the
WTRU measurement parameters described previously.
[0174] Additionally, the WTRU may also use the following criteria
and triggers individually or in any combination to trigger the
report. The criteria include the WTRU in connected mode and the
load in the WTRU may be above a threshold, perhaps for a defined
period of time. The threshold and/or time may be explicitly
configured by the network or predefined in the WTRU. The threshold
and/or time may be configured when the event, measurement type,
and/or capability is configured as described above, or when one of
the thresholds from other measurement types, for example, traffic
volume measurement (TVM)) may be used. Also, triggering a report
may be through a predetermined service or application configured in
the WTRU and whether the WTRU may be in a specific mobility state
such as a high mobility state, for example.
[0175] Alternatively, the WTRU may send the vicinity report
additional times based upon a network signal, WTRU standard, or an
autonomously determined timer expiration. This may be based on
determining that the WTRU is in the same location and there was no
reaction at the first report from the network side. In some
embodiments, the number of the vicinity reports may be limited by
the network to a signaled value or determined by a standard value.
This may be done, for example, in order to limit the WTRU attempts
and reduce the network signaling load.
[0176] Embodiments contemplate that if the WTRU sends the vicinity
report based on the previously discussed triggers and/or a
combination of triggers, the WTRU may send a new report informing
the network that the WTRU may be moving away from the current
vicinity area. This report may be based on one or any combination
of the following triggers. The triggers may be based on detecting
positioning methods indicating the WTRU may be leaving the
previously signaled vicinity area. They may include a network
configured location algorithm that may be combined with a time to
trigger timer and/or based on a WTRU location approximation
algorithm that may be combined with a time to trigger timer. The
triggers may include detecting a high mobility state for a defined
period of time that may be signaled by the network and/or the WTRU
autonomously. The triggers may also include the measured dormant
cell falling below a threshold for a defined period of time, for
example.
[0177] The status of a handover command may be network signaled or
WTRU determined upon expiration of a timer which was started after
sending the vicinity report. This may be combined optionally with a
counter for maximum number of reports that the WTRU may be allowed
to send. The maximum number of reports may be network signaled,
standard fixed value, or a WTRU autonomously determined value.
[0178] Embodiments contemplate that in order to provide vicinity
information, the network may configure the WTRU with one or more
new measurement events. Such events, which may be referred to as
VICINITY Event, may include a combination of one or more criteria
that either individually met and/or once all are net may trigger
the event.
[0179] Alternatively, an existing measurement type or event may be
used and extended to include criteria for reporting such
information. Alternatively, a new measurement type may be
introduced. The WTRU may be configured with new measurement types,
existing measurement types, new events, and/or existing events that
may enable the search capabilities to allow the WTRU to report its
vicinity.
[0180] Alternatively, an explicit message from the network may be
used to enable/disable this search capability in the WTRU. In some
embodiments, if the event or mechanism is not configured by the
network, the WTRU may disable this functionality.
[0181] Embodiments contemplate one or more potential measurement
configurations. In a potential measurement configuration, one set
of criteria may include the measured path loss from one or more
cells being within a configured range. For example, the network may
configure the WTRU with one or more criteria each referring to a
specific cell and a measurement quantity and reporting range.
Measurement quantity may be comprised of path loss, Common Pilot
Channel Received Signal Code Power (CPICH RSCP), CPICH Ec/No, or
any other measurement. Table 1 shows an example where the WTRU may
be configured with three different measurements. Once the WTRU
determines that the measured quantities are within their respective
configured range, a MEASUREMENT REPORT with event VICINITY may be
triggered by the WTRU.
[0182] Additionally, other possible configurations may also include
the primary synchronization code (PSC) or physical cell identity
(PCI) associated to a cell. Alternatively, only one threshold may
be provided for a number of PSCs or PCI. Once the WTRU determines
that the quality of the requested cells, for example one or more,
may be above a threshold, the WTRU may trigger one or more
reports.
[0183] Table 1 may be used for example purposes. The configuration
provided to the WTRU may include one or more cells with one or more
thresholds that may not necessarily have a one to one mapping. In
some embodiments, all of these conditions may need to persist for a
time to trigger or other defined timer prior to triggering the
report.
TABLE-US-00001 TABLE 1 Target cell Measured Min range Max range
Criterion ID information quantity value value 1 Cell Info 1 Path
Loss X1 dB Y1 dB 2 Cell Info 1 CPICH RSCP X2 dB Y2 dB 3 Cell Info 1
Path Loss X3 dB Y3 dB
[0184] Alternatively or additionally, the network may also provide
location-base triggers when the WTRU or network may support
positioning. In such cases, the network may configure the WTRU with
a location position (e.g.: in actual coordinates) information and a
range (e.g., radius in meters). A measurement report may be
triggered at the WTRU when the WTRU detects that its location is
within the configured range. Table 2 illustrates an example where
the WTRU may be configured to trigger a measurement report when it
is within X meters of Position1.
TABLE-US-00002 TABLE 2 Criterion ID Target position Range (radius
in m) 4 Position1 X
[0185] Embodiments contemplate that assisted positioning mechanisms
other than GPS may used such as Observed Time Different Of Arrival
(OTDOA), in which case the network may configure the WTRU
appropriately, perhaps with the inclusion of Idle Periods in
Downlink (IPDL) configuration. Embodiments also contemplate
position and CPICH-based measurements may also be combined in order
to provide an extended set of criteria. For example, Criterion 1-4
of Tables 1 and/or 2 may be combined and when all of these are met,
a single MEASUREMENT REPORT may be sent to the network. The
MEASUREMENT REPORT may contain the measured quantity and/or
positioning measured results from all configured criterion, in
addition to the cause, e.g. VICINITY EVENT. Alternatively, this may
be autonomously determined by the WTRU based on previously measured
and connected cells. The network may configure the WTRU to start
measurements and determination on its side. For example, based on
fingerprint information, measurements of the neighboring cells or
other location services such as GPS, the WTRU may determine to be
in the vicinity of a previously connected cell and the WTRU may
rigger a report.
[0186] Embodiments contemplate that the report may indicate that
the WTRU triggers may be based on any of the triggers discussed
previously. The WTRU may indicate the cell identify or global cell
identity of the cell it was previously connected to but may be no
longer available in the current location. Optionally, the WTRU may
report the cell identity of more than one cell.
[0187] Additionally, the WTRU may also indicate the frequency and
potentially the radio access technology (RAT) of this cell. This
level of specific information may help the network determine
exactly which cell the WTRU may potentially connect to if it was
power-on. Based on the cell identity, or cell identities, the
network may determine exactly which cell to power on using any of
the solutions described above. In some embodiments, any of these
reports may be triggered using any radio resource control (RRC)
message or a measurement report. Alternatively, the WTRU may report
this capability to the network, upon initial RRC setup procedures,
such RRC Connection Setup Complete, RRC Connection Request, and/or
using the WTRU radio access capability.
[0188] Embodiments contemplate that the network may issue an
initial measurement configuration message to the WTRU. During the
period over which the WTRU may be performing measurements, the WTRU
may be configured to send a request for network services, which may
be needed to accomplish certain types of measurements, to the RNC.
For example, such services may include but are not limited to: IPDL
support from network and/or compressed mode support from
network.
[0189] FIG. 9 shows an example of a WTRU autonomous measurement and
report method. At 901, the WTRU may be configured to receive a
measurement configuration from the RNC (via RRC signaling for
example). At 902, the WTRU may be configured to perform the
measurement configuration. At 903, the WTRU may determine that it
needs a network service for carrying a specific measurement and the
WTRU sends a (new) NETWORK SERVICE REQUEST message with the type of
service specified as parameter (e.g., IPDL, Compressed mode, etc.).
At 904, the WTRU may be configured to receive a NETWORK SERVICE
ACKNOWLEDGE message potentially carrying additional parameter
information (e.g., IPDL, Compressed mode parameters). At 905, the
request network service may remain ongoing. At 906, the WTRU may be
configured to perform measurements and, when vicinity criteria may
be met, report to the RNC that it is within the vicinity of a
remote access point. For example, the WTRU may transmit a
MEASUREMENT REPORT or a new message (e.g., VICINITY REPORT). At
907, the RNC may be configured to instruct the WTRU to stop the
measurement via MEASUREMENT CONTROL message or upon the HANDOVER
decision made by the RNC.
[0190] Embodiments contemplate one or more methods by which a
target cell may be controlled for measurement in a low activity
state. For example, embodiments contemplate that, the controlling
RNC (CRNC) may be informed by the way of a measurement report or a
new message over the Iur interface from the (DRNC) that may control
the source cell, about the vicinity of a WTRU to the femto cell,
and the femto cell may be marked as being in dormant mode. The Iur
may be the link between the network entities of the RNC (Radio
Network Controller) and DRNC (Drift Radio Network Controller), for
example. When this occurs, the CRNC may perform the following in
any combination actions or in order to allow the WTRU to measure
the femto/pico cell.
[0191] If the WTRU may be on an intra frequency and the femto cell
may be an intra frequency cell, the CRNC may send a WAKE UP CPICH
message to the dormant cell. The WAKE UP CPICH may contain a period
of time if the CPICH, and potentially the SCH and/or Broadcast
Channel Primary Common Control Physical Channel (BCH (P-CCPCH))
channels, may be broadcast by the femto cell for a limited period
of time, for example. Embodiments also contemplate that if the
femto cell is an CSG (Closed Subscriber Group) HNB, then the CRNC
may, and in some embodiments perhaps must, inform the core network
that the HNB cell may, and in some embodiments perhaps must, be put
back in service. Due to what may be the particular architecture of
the HNB's connection to the core network, a specific WAKE UP
message from the HNB's core network controlling node may be sent to
the HNB_GW (HNB gateway). The gateway may then convey this WAKE UP
message to the appropriate HNB that the gateway controls.
Embodiments contemplate that a communication tunnel may, and in
some embodiments must, be created between the CRNC and the HNB
during this operation. Alternatively or additionally, a
communication tunnel may exist temporarily or permanently under the
form of an Iur type interface since the HNB may be partly an RNC as
well. This message may, and in some embodiments must, be
acknowledged and the acknowledge message may, and in some
embodiments must, be conveyed to the CRNC that initiated the WAKE
UP. This message may contain some or all of the parameters
specified in the message for the dormant cell.
[0192] Embodiments contemplate that for a time limited wake up, the
control channels (MIB and SIB3 at least for CSG ID identification)
may, and in some embodiments must, be transmitted for a period of
time, for example approximately several seconds, in order to allow
the WTRU to acquire the MIB and the CSG ID).
[0193] Embodiments contemplate that WRTU may not be a member of the
CSG HNB cell. If the WRTU is not a member of the CSG HNB cell, the
CRNC may send a message to the HNB that may allow the HNB to go
back to sleep/dormant mode at the end of the procedure.
Alternatively, if the WRTU is a CSG member of the HNB, the CRNC may
start the inbound mobility procedure in order to handover the WRTU
to the HNB. If the WTRU is a member of the CSG HNB, the HNB may
start a timer and if it does not receive the dormant/sleep message
order before the timer expiration, it may return to normal
operation as in inbound handover procedure may be ongoing.
Alternatively, the CSG HNB may return to normal operation upon
handover confirmation, perhaps when the WRTU may already be in
connected mode and served by the CSG HNB.
[0194] Upon reception of the WAKE UP CPICH message, the dormant
femto cell may turn ON its transceiver and may start broadcasting
the CPICH, and in some embodiments, the SCH and/or BCH (P-CCPCH)
channels. If the limited period of time is indicated, then after
expiration the femto cell may turn OFF the CPICH, and in some
embodiments the SCH and/or BCH (P-CCPCH) channels, and may turn off
its transceiver as per dormant mode requirements. Upon returning to
dormant mode, the femto cell may send an indication to the CRNC
informing it about the transition, perhaps over the communication
tunnel opened at the initiative of the CRNC, for example.
[0195] If the femto cell receives another WAKE UP CPICH message
from the CRNC while executing the first CPICH WAKE UP order, the
femto cell may extend the CPICH, and in some embodiments, the SCH
and/or BCH (P-CCPCH) channels, broadcast with the indicated time
period, or indefinitely if the period of time is not indicated.
[0196] Alternatively, if the period of time element is not present
in the WAKE UP CPICH message, the femto cell may turn ON its CPICH,
and in some embodiments the SCH and/or BCH (P-CCPCH) channels, and
may keep the CIPCH ON until a new entry into dormant mode order may
be received from the CRNC.
[0197] Alternatively, the limited period of time for CPICH, and in
some embodiments the SCH and/or BCH (P-CCPCH) channels broadcast,
may start after a time delay that may be calculated by the CRNC
based on initial vicinity measurements that may be provided by the
WTRU, for example. If the CPICH, and in some embodiments the SCH
and/or BCH (P-CCPCH) channels, may broadcast for a limited time,
the CRNC may send a measurement control to the WTRU containing at
least one of the PSC to measure, the period of time for CPICH
broadcast (if is limited), and the delay offset if there is a time
delay.
[0198] Embodiments contemplate that the CPICH, and in some
embodiments the SCH and/or BCH (P-CCPCH) channels, may broadcast a
period of time which may be computed based on (but not limited to)
the period measurements interval, time to trigger for intra
frequency events, and/or location measurements as described
herein.
[0199] Alternatively, the CRNC may not use a limited period of time
for CPICH broadcast, and in some embodiments the SCH and/or BCH
(P-CCPCH) channels, and once started may keep it ON until the WTRU
may send measurement reports. Upon received measurement reports
and/or events from WTRU, the CRNC may decide to turn on in active
mode the femto cell and perform a handover or to return it to
dormant mode.
[0200] If the femto cell is operating on inter frequency, the CRNC
may adapt the CPICH, and in some embodiments the SCH and/or BCH
(P-CCPCH) channels, broadcast period to the inter frequency
reporting interval, and may provide the WTRU with at least one of a
measurement gaps configuration, the CPICH broadcast activation
time, the gaps activation time or time offset, and/or the CPICH
broadcast limited time if the cell is operating in this mode (inter
frequency), for example. The CRNC may use a Measurement Control RRC
message with one or more new IE to send the previously described
parameters or a new dedicated RRC message.
[0201] Embodiments contemplate that in the case of a limited time
broadcast of the CPICH, and in some embodiments the SCH and
possibly BCH (P-CCPCH) channels, the target cell may be barred for
service in order to avoid other WTRUs accidentally camping on the
target cell. In such an instance, the target cell may return to
normal service (e.g., not be barred) upon full activation.
[0202] Embodiments contemplate methods that may allow a NodeB to go
autonomously in dormant mode based on a set of measurements and
triggers. For example, the femto cell may receive from the CRNC a
dormant mode time to trigger parameter. This may occur in case of
inactivity as one of the femto cell configuration parameters as a
new IE, as well as the low activity detection parameters to
supervise that may or perhaps will serve as a trigger. For example,
if the femto cell is configured as described with criteria to
trigger it to go into dormant mode, this criteria may be provided
as a new IE (information element) in the femto cell configuration
parameters. If the inactivity criteria described/defined by the IE
or the femto cell configuration is met, then the cell may
autonomously become dormant.
[0203] Upon detection of a low activity, meaning no WTRU context
for the time to trigger interval, or very few WTRU contexts
registered with the femto cell with no connected mode activity for
a time to trigger interval, the femto cell may send a message over
the NBAP interface informing the CRNC of its intention to go in
dormant mode. Alternatively, low activity when no WTRUs are
registered with the femto cell may be triggered by the lack of
access request for a defined time to trigger interval. Also
alternatively, the femto cell may receive a defined time schedule
for its CRNC for active state/dormant mode. In such embodiments,
the femto cell may follow the schedule supplied by its CRNC and go
into dormant mode without considering other low activity triggers,
for example.
[0204] Alternatively, in some embodiments, the femto cell may apply
the previously described self-decision algorithm for going in
dormant mode only in the periods scheduled by CRNC. The CRNC may
confirm the femto cell with a cell reconfiguration message with the
dormant mode indicator set to enter dormant mode, or alternatively,
just mark the cell as in dormant mode and start a supervision
algorithm described in the above sections.
[0205] Embodiments contemplate methods that may allow a NodeB to
autonomously exit the dormant mode based at least on a set of
measurements and triggers. For example, embodiments contemplate
that the CRNC may include in the cell configuration parameters a
new IE for the dormant mode schedule. In particular, defined time
intervals may be specified for the dormant mode and active state in
which the femto cell may follow. Based on the previously described
schedule, the femto cell may decide to wake up and stay active
based on the schedule, which in some embodiments may be a strict
schedule.
[0206] Alternatively, the CRNC may provide the femto cell with a
more complex schedule, where the dormant mode may be conditioned by
activity parameters and/or the dormant mode may be a DTX cycle or a
dormant mode with short wake up periods, for example. The CRNC may
specify a periodic wake up schedule while the femto cell is
dormant. This wake up schedule may include the full active state
and the criteria to go back to sleep may be any or a combination of
the methods described herein based on the strict schedule or a low
activity detection, for example.
[0207] Alternatively, in some embodiments, the CRNC may wake up the
femto cell only with CPICH in DTX mode while in dormant mode based
on a strict schedule that can be used to synchronize measurements
for the WTRUs in vicinity as described previously.
[0208] 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 incorporate 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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