U.S. patent application number 15/609495 was filed with the patent office on 2017-09-14 for method and apparatus for detecting and measuring for home node-bs.
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 Sylvie Gomes, Paul Marinier, Diana Pani.
Application Number | 20170265099 15/609495 |
Document ID | / |
Family ID | 42710666 |
Filed Date | 2017-09-14 |
United States Patent
Application |
20170265099 |
Kind Code |
A1 |
Pani; Diana ; et
al. |
September 14, 2017 |
METHOD AND APPARATUS FOR DETECTING AND MEASURING FOR HOME
NODE-BS
Abstract
Methods and apparatus are disclosed for a wireless
transmit/receive unit (WTRU) to detect and perform measurements
with respect to Home Node-Bs (HNB) and Home evolved Node-Bs
(H(e)NB) (collectively "HNB"). The methods may include generating
and transmitting a request for a measurement configuration that may
include gap allocations to detect and measure a primary scrambling
code or a physical cell identity of a target HNB for at least one
frequency or radio access technology (RAT). The request may be in
response to the WTRU entering a HNB cell for which the WTRU has
stored fingerprint information and whose closed subscriber group ID
is in the WTRU's whitelist. The network may configure the WTRU to
measure the requested frequency or RAT in response to the proximity
report/request. Methods are described for releasing the measurement
configuration.
Inventors: |
Pani; Diana; (Montreal,
CA) ; Marinier; Paul; (Brossard, CA) ; Gomes;
Sylvie; (Manhasset, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
INTERDIGITAL PATENT HOLDINGS, INC. |
Wilington |
DE |
US |
|
|
Assignee: |
INTERDIGITAL PATENT HOLDINGS,
INC.
Wilmington
DE
|
Family ID: |
42710666 |
Appl. No.: |
15/609495 |
Filed: |
May 31, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14626235 |
Feb 19, 2015 |
9686707 |
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15609495 |
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14106077 |
Dec 13, 2013 |
8996015 |
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14626235 |
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|
12818474 |
Jun 18, 2010 |
8634836 |
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14106077 |
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61218824 |
Jun 19, 2009 |
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61248003 |
Oct 2, 2009 |
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61247968 |
Oct 2, 2009 |
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61250255 |
Oct 9, 2009 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 24/10 20130101;
H04W 48/20 20130101; H04W 84/045 20130101; H04W 8/005 20130101;
H04W 48/16 20130101; H04W 36/0085 20180801 |
International
Class: |
H04W 24/10 20060101
H04W024/10 |
Claims
1. A method performed by a network entity, the method comprising:
receiving an indication from a wireless transmit/receive unit
(WTRU) that is configured to detect, based on autonomous search
functionality, that the WTRU has entered into a proximity of a home
Node-B or home evolved Node-B (HNB) cell whose closed subscriber
group (CSG) ID is in a whitelist of the WTRU, wherein the
indication includes a frequency of the HNB cell and a Radio Access
Technology (RAT) of the HNB cell; transmitting a measurement
configuration message to the WTRU to perform measurements on the
HNB cell.
2. The method of claim 1, wherein the indication is received from
the WTRU after the WTRU previously encountered the HNB cell.
3. The method of claim 1, wherein the measurement configuration
message enables the WTRU to detect one of a primary scrambling code
(PSC) or a physical cell identity (PCI) of the HNB cell on the
frequency and the RAT.
4. The method of claim 3, wherein the measurement configuration
message indicates to the WTRU to measure the frequency or the RAT
with one of a compressed mode or measurement gap.
5. The method of claim 1, wherein the measurement configuration
message comprises one of an intra-frequency measurement,
inter-frequency measurement, or inter-RAT measurement.
6. The method of claim 1, wherein the indication indicates a cell
identity of the HNB cell that triggered the indication.
7. The method of claim 1, further comprising receiving, from the
WTRU, an indication of support of HNB cell detection on the
frequency and RAT.
8. The method of claim 1, further comprising transmitting a
configuration for the RAT to the WTRU, wherein the configuration
enables proximity detection and sending/receiving of reports in
response to proximity detections on a condition that the WTRU
enters or exits the proximity of the HNB cell.
9. The method of claim 1, further comprising receiving a
notification from the WTRU that the WTRU is exiting the proximity
of the HNB cell whose CSG ID is in the whitelist of the WTRU.
10. The method of claim 9, further comprising transmitting a
configuration removing a measurement configuration.
11. The method of claim 1, wherein the indication is not received
from the WTRU more than a certain number of times during a certain
period of time
12. The method of claim 1, wherein the network entity is a base
station.
13. A network entity, comprising: a processor; a receiver in
communication with the processor; the processor and receiver
configured to receive an indication from a wireless
transmit/receive unit (WTRU) that is configured to detect, based on
autonomous search functionality, that the WTRU has entered into a
proximity a home Node-B or home evolved Node-B (HNB) cell whose
closed subscriber group (CSG) ID is in a whitelist of the WTRU,
wherein the indication includes a frequency of the HNB cell and a
Radio Access Technology (RAT) of the HNB cell; a transmitter in
communication with the processor; the transmitter configured
transmit a measurement configuration message to the WTRU to perform
measurements on the HNB cell.
14. The network entity of claim 13, wherein the indication is
received from the WTRU after the WTRU previously encountered the
HNB cell.
15. The network entity of claim 13, wherein the measurement
configuration message enables the WTRU to detect one of a primary
scrambling code (PSC) or a physical cell identity (PCI) of the HNB
cell on the frequency and the RAT.
16. The network entity of claim 15, wherein the measurement
configuration message indicates to the WTRU to measure the
frequency or the RAT with one of a compressed mode or measurement
gap.
17. The network entity of claim 13, wherein the measurement
configuration message comprises one of an intra-frequency
measurement, inter-frequency measurement or inter-RAT
measurement.
18. The network entity of claim 13, wherein the indication
indicates a cell identity of the HNB cell that triggered the
indication.
19. The network entity of claim 13, wherein the receiver is further
configured to receive, from the WTRU, an indication of support of
HNB cell detection.
20. The network entity of claim 13, wherein the transmitter is
further configured to transmit a configuration for the RAT to the
WTRU, wherein the configuration enables proximity detection and
sending/receiving of reports in response to proximity detections on
a condition that the WTRU enters or exits the proximity of the HNB
cell.
21. The network entity of claim 13, wherein the receiver is further
configured to receive a notification from the WTRU that the WTRU is
exiting the proximity of the HNB cell whose CSG ID is in the
whitelist of the WTRU.
22. The network entity of claim 21, wherein the transmitter is
further configured to transmit a configuration removing a
measurement configuration.
23. The network entity of claim 13, wherein the indication is not
received from the WTRU more than a certain number of times during a
certain period of time.
24. The network entity of claim 13, wherein the network entity is a
base station.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 14/626,235 filed Feb. 19, 2015, which is a
continuation of U.S. patent application Ser. No. 14/106,077 filed
Dec. 13, 2013, which issued as U.S. Pat. No. 8,996,015 on Mar. 31,
2015, which is a continuation of U.S. patent application Ser. No.
12/818,474 filed Jun. 18, 2010, which issued as U.S. Pat. No.
8,634,836 on Jan. 21, 2014, which claims the benefit of U.S.
provisional application No. 61/218,824 filed Jun. 19, 2009; U.S.
provisional application No. 61/248,003 filed Oct. 2, 2009; U.S.
provisional application No. 61/247,968 filed Oct. 2, 2009; and U.S.
provisional application No. 61/250,255 filed Oct. 9, 2009, the
contents of which are hereby incorporated by reference herein.
FIELD OF INVENTION
[0002] This application is related to wireless communications.
BACKGROUND
[0003] Home Node-Bs (HNBs) for Universal Mobile Telecommunications
System (UMTS) and Home e-Node-Bs (HeNBs) for Long Term Evolution
(LTE) (collectively, "Home Node-Bs" (HNBs)), have been introduced
in Release 8 of the 3rd Generation Partnership Project (3GPP)
standard, for example, to increase cellular coverage and overall
system throughput. HNBs are physical devices (e.g., similar to
wireless local area network (WLAN) access points (APs)) that
provide access to UMTS and/or LTE services over extremely small
service areas (or cells), such as private homes, small offices and
coffee shops. As opposed to WLAN APs, which are generally
accessible by wireless devices within their ranges, access to HNBs
may be limited to smaller, more select groups of users referred to
as closed subscriber groups (CSGs). Similar to WLAN APs, however,
HNBs connect their users' wireless devices to the HNB operator's
core network. For HNBs, the connection may be established using,
for example, an internet connection (e.g., a digital subscriber
line (DSL)). By way of example, a coffee shop owner (or subscriber)
may choose to deploy an HNB in his or her shop to provide patrons
(the CSG in this example) with a stronger wireless connection than
may otherwise be available inside the shop. Due to their use in
small service areas, HNBs may be densely deployed and, accordingly,
located within the coverage area of one or more macro Node-Bs.
[0004] To enable certain functionalities for wireless devices or
wireless transmit/receive units (WTRUs), such as handover (HO)
between network nodes, it may be necessary for the WTRU to perform
measurements, for example, on other frequencies or systems. To
perform these measurements, the WTRU may require gaps.
[0005] Inter-frequency measurement reporting rules do not cover
scenarios where it may be preferable for the WTRU to handover from
a macro cell frequency to an HNB frequency, even if the quality of
the macro cell frequency is still acceptable. The network typically
configures the WTRU for compressed mode with gaps to measure other
frequencies when the WTRU is at the border of one or more cells and
needs to handover to another frequency.
[0006] The inter-frequency measurement reporting rules rarely apply
to HNBs, which may be, for example, deployed in private homes
localized anywhere in the macro cell coverage area (as described
above). Nevertheless, a user may prefer to handover from a macro
cell to an HNB, even if the quality of the frequency of the serving
macro cell is above a predetermined threshold. To handover the WTRU
from a macro cell to an HNB, the network may need to configure the
user's WTRU for compressed mode in order to detect the HNB primary
scrambling codes (PSCs) (applicable to UMTS HNBs) or physical cell
identities (PCIs) (applicable to LTE HNB) on other frequencies.
SUMMARY
[0007] Methods and apparatus for a wireless transmit/receive unit
(WTRU) to detect and perform measurements with respect to Home
Node-Bs (HNB) and Home evolved Node-Bs (H(e)NB) (collectively
referred to as "HNB") on a frequency and other systems are
disclosed. The methods may include generating and transmitting a
request for a measurement configuration that may include a request
for an allocation of gaps to detect and measure a primary
scrambling code (PSC) or a physical cell identity (PCI) of a target
HNB for at least one frequency or radio access technology. The
request may be in response to the WTRU entering a HNB cell for
which the WTRU has stored fingerprint information and whose closed
subscriber group (CSG) ID is in the WTRU's whitelist. The request
sent by the WTRU may include the frequency, fingerprint
information, cell identification and other similar information. In
addition, methods are described for releasing the measurement
configuration including any gaps. The network may configure the
WTRU to measure the requested frequency or RAT in response to the
vicinity/proximity report/request.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] A more detailed understanding may be had from the following
description, given by way of example in conjunction with the
accompanying drawings wherein:
[0009] FIG. 1 is an example of a Home Node-B (HNB) or Home
(evolved) Node-B (H(e)NB) (collectively referred to as HNB)
deployment in a wireless communication system;
[0010] FIG. 2 is an example of a wireless communication system that
may be used with the system of FIG. 1;
[0011] FIG. 3 is an example functional block diagram of a wireless
transmit/receive unit (WTRU) and the Node-B of the wireless
communication system of FIG. 2;
[0012] FIG. 4 is another example of a wireless communication system
that may be used with the system of FIG. 1;
[0013] FIG. 5 is an example functional block diagram of a WTRU and
the Node-B of the wireless communication system of FIG. 4;
[0014] FIG. 6 is an example functional block diagram of another
WTRU of the wireless communication system of FIGS. 2 and 4;
[0015] FIG. 7 is an example method with respect to a WTRU entering
a cell of a HNB; and
[0016] FIG. 8 is an example method with respect to a WTRU exiting a
cell of a HNB.
DETAILED DESCRIPTION
[0017] When referred to hereafter, 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. When referred to hereafter, 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. A Home Node-Bs (HNBs) and Home e-Node-Bs (HeNBs)
(collectively referred to as (HNBs)) may be a WTRU, a base station
or a combination thereof.
[0018] HNBs have been introduced in long term evolution (LTE) and
Universal Mobile Telecommunications System (UMTS), respectively, as
part of an effort to provide improved spectral efficiency, reduced
latency, and better utilization of radio resources for faster user
experiences, richer applications and lower cost services. The HNB
provides subscribers with access to network services over extremely
small service areas, such as homes or small offices. A subscriber
(e.g., an individual or an organization) may deploy a HNB over an
area where such service is desired. In general, an HNB cell may be
any cell that broadcasts a closed subscriber group (CSG) ID. The
HNB cell may refer to a CSG cell or a hybrid cell. A CSG cell
refers to a defined area over which radio coverage provided by the
HNB may only be accessed by a group of subscribers authorized, via
the CSG ID, to use the services of the cell. A hybrid cell refers
to a cell that has a defined area over which radio coverage
provided by the HNB corresponds to a CSG ID but which is accessible
by non-member WTRUs. HNBs may be deployed on the same carrier as
open or macro base stations and may also be deployed in a dedicated
carrier. In general, a macro cell refers to a defined area over
which radio coverage is provided by a base station (also referred
to as a normal or open cell). In certain situations, the macro cell
may also refer to a CSG cell.
[0019] Although the terminology used herein generally corresponds
to Universal Mobile Telecommunications System (UMTS) technology,
the concepts described herein are applicable to other wireless
technologies such as LTE. Therefore, for example, if the term
primary scrambling codes (PSC) is used herein, this may be
considered as equivalent to physical cell identities (PCI) in LTE.
Further, the terms compressed mode gaps and measurement gaps are
used interchangeably herein and are collectively referred to
hereafter as "gaps." These "gaps" refer to the gaps that the WTRU
may require to perform measurements on at least one frequency and
on other systems. Additionally, the gaps may correspond to
compressed mode gaps for UMTS and measurement gaps for LTE. Even
further, the term Cell Global Identity (CGI) may refer to the LTE
CGI as well as to the UMTS Cell Identity (CI) broadcast in the
system information of the cell.
[0020] To enable certain functionalities for wireless devices or
wireless transmit/receive units (WTRUs), such as handover (HO)
between network nodes, it may be necessary for the WTRU to perform
measurements, for example, of cells on a certain frequency or
systems. To perform these measurements, the WTRU may require a
measurement configuration which may include a pattern in time
during which the WTRU is allowed to interrupt reception on its
serving cell for the purpose of performing measurements in the same
or other frequencies and other radio access technologies (RATs).
Such pattern may correspond to compressed mode gaps in UMTS, or
measurement gaps in LTE, and will be referred to as "gaps"
hereinafter.
[0021] Measurement configurations may include a number of
measurement types such as inter-frequency measurements,
intra-frequency measurements, and inter-RAT measurements which
assist the network for handover (HO) purposes. For both UMTS and
LTE, these measurement types are configured by the network, and the
WTRU may measure on a certain frequency or radio access technology
(RAT) if configured with such events. In some cases, in order to
make measurements on at least one frequency or RAT, the network has
to configure the WTRU with gaps. Some, inter-frequency measurement
report events specified in the 3GPP standards for UMTS and LTE
include (assuming single-radio implementation): Event 2a ("Change
of best frequency"); Event 2b ("The estimated quality of the
currently used frequency is below a certain threshold and the
estimated quality of a non-used frequency is above a certain
threshold"); Event 2c ("The estimated quality of a non-used
frequency is above a certain threshold"); Event 2d ("The estimated
quality of the currently used frequency is below a certain
threshold"); Event 2e ("The estimated quality of a non-used
frequency is below a certain threshold"); and Event 2f ("The
estimated quality of the currently used frequency is above a
certain threshold"). The measurements required to evaluate the
criteria for these events may require the WTRU to be configured
with gaps.
[0022] Measurements on at least one frequency or RAT may be power
consuming and may result in some service degradation when gaps are
required to take the measurements. Therefore, by default, wireless
devices may not be configured to measure on at least one frequency
or RAT. The network may rely on the reception of a measurement
report (e.g., Event 2D), which indicates that the quality of the
currently used frequency is below a threshold. In such a situation,
the network may then configure the WTRU to start taking
measurements on a frequency or RAT and may additionally configure
the WTRU with gaps.
[0023] For LTE, the following events may be configured for an
inter-frequency measurement type: Event A3 (Neighbor becomes amount
of offset better than serving); Event A4 (Neighbor becomes better
than absolute threshold); and Event A5 (Serving becomes worse than
absolute threshold1 and Neighbor becomes better than another
absolute threshold2). In a typical single-radio implementation,
gaps may generally need to be configured to ensure a minimum time
for the WTRU to perform measurements.
[0024] Existing measurement reporting rules do not cover scenarios
where it may be preferable for the WTRU to handover from a macro
cell frequency to an HNB frequency, even if the quality of the
macro cell frequency is still acceptable. The network typically
configures the WTRU to measure on another frequency or RAT when the
WTRU is at the border of one or more cells and needs to handover to
another cell, frequency or RAT. Given that for HNBs, the network is
not aware of the deployment or whether a WTRU is allowed to connect
to a HNB that is under the coverage of a macro cell, the network
may not know when to configure the WTRU to perform HNB measurements
on at least one frequency or RAT.
[0025] Disclosed herein are methods and apparatus for facilitating
a wireless transmit/receive unit (WTRU) to detect HNBs, measure a
frequency or RAT with respect to the HNB and release measurement
configurations that may include gaps. The methods may include
generating and transmitting a request for a measurement
configuration that may include a request for an allocation of gaps
to detect and measure a PSC or PCI of a target HNB for at least one
frequency or RAT. The request may be in response to the WTRU
entering the proximity or vicinity of a HNB cell for which the WTRU
has stored fingerprint information (i.e., autonomous search
functionality) and whose closed subscriber group (CSG) ID is in the
WTRU's whitelist. This may be determined in WTRU by means of WTRU
specific fingerprint information. The WTRU whitelist includes the
CSG IDs of the HNBs the WTRU may be allowed to access. The request
sent by the WTRU may include the frequency, RAT, cell
identification and other similar information. The network may then
configure the WTRU to measure the requested frequency or RAT in
response to the vicinity/proximity report/request. In addition,
methods are described for releasing the measurement configuration
including gaps. The request for releasing measurement configuration
may be in response to the WTRU leaving the vicinity of a HNB cell
whose CSG ID is in the WTRU's whitelist, in accordance with stored
fingerprint information (i.e. an autonomous search
functionality).
[0026] It is understood that the methods disclosed herein are
applicable and may be configured for inter-frequency, inter-radio
access technology (RAT) and intra-frequency measurements of HNB
cells or frequencies.
[0027] FIG. 1 shows an example of a HNB deployment in a wireless
communication system 100. The wireless communication system 100
includes an LTE open-cell 105, a 3GPP system cell 110, a higher
network node (e.g., gateway) 115 and/or a mobility management
entity (MME)/serving general packet radio service (GPRS) support
node (SGSN) 120. The higher network node 115 is responsible for
coordinating the operation of several HNBs 125A, 125B and 125C.
Alternatively, the MME/SGSN 120 may be responsible for coordinating
the operation of several HNBs 125A, 125B and 125C. The MME is the
LTE equivalent of a 3G/2G SGSN/GGSN. The relationship between the
LTE open-cell 105 and other 3GPP systems 110, (e.g., WCDMA/global
system for mobile communications (GSM)), is that there may be areas
where the coverage of these two technologies overlap. It is similar
to simultaneous coverage of GSM and WCDMA technologies. The higher
network node 115 may be a gateway function which interfaces with
the MME/SGSN 120. As a gateway, the role of the higher network node
115 may be to act as a single open-cell towards the MME/SGSN 120
while supporting several small home cells or CSG cells.
[0028] FIG. 2 is a block diagram of an example wireless
communication system 200 that works with system 100 and may include
a plurality of WTRUs 210, a Node-B 220, a controlling radio network
controller (CRNC) 230, a serving radio network controller (SRNC)
240, and a core network 250. The Node-B 220 and the CRNC 230 may
collectively be referred to as the Universal Terrestrial Radio
Access Network (UTRAN) 235.
[0029] The WTRUs 210 illustrated in FIG. 2 are in communication
with the Node-B 220, which is in communication with the CRNC 230
and the SRNC 240. Although three WTRUs 210, one Node-B 220, one
CRNC 230, and one SRNC 240 are shown as included in the example
system 200 of FIG. 2, any combination of wireless and wired devices
may be included in a wireless communication system.
[0030] FIG. 3 is a functional block diagram 300 of one of the WTRUs
210 and the Node-B 220 of the example wireless communication system
200 of FIG. 2. In general, the WTRU 210 illustrated in FIG. 3 is in
communication with the Node-B 220, and both the WTRU 210 and the
Node-B 220 are configured to detect HNBs, receive configuration
information, measure at least one frequency or RAT with respect to
the HNB and release measurement configurations that may include
gaps with respect to a WTRU entering or exiting a HNB cell. In the
UMTS architecture, the SRNC sends the configuration information and
processes the measurements.
[0031] In addition to the components that may be found in a typical
WTRU, the example WTRU 210 includes a processor 315, a receiver
316, a transmitter 317, a memory (not shown) and an antenna 318.
The memory may be provided to store software including, for
example, an operating system, application, and other such software.
The processor 315 may be configured to, alone or in association
with the software, detect HNBs, receive configuration information,
measure at least one frequency or RAT with respect to the HNB and
release measurement configurations that may include gaps with
respect to a WTRU entering or exiting a HNB cell. The receiver 316
and the transmitter 317 are in communication with the processor
315. The antenna 318 is in communication with both the receiver 316
and the transmitter 317 to facilitate transmission and reception of
wireless data.
[0032] In addition to the components that may be found in a typical
base station, the Node-B 220 includes a processor 325, a receiver
326, a transmitter 327, and an antenna 328. The processor 325 may
be configured to, alone or in association with the software, detect
HNBs, detect entering or leaving the vicinity/proximity of a HNB,
receive configuration information that may include gaps, measure at
least one frequency or RAT with respect to the HNB and release
measurement configurations that may include gaps with respect to a
WTRU entering or exiting the vicinity/proximity of a HNB cell. The
receiver 326 and the transmitter 327 are in communication with the
processor 325. The antenna 328 is in communication with both the
receiver 326 and the transmitter 327 to facilitate the transmission
and reception of wireless data. In the UMTS architecture, the SRNC
sends the configuration information and processes the
measurements.
[0033] FIG. 4 shows a Long Term Evolution (LTE) wireless
communication system/access network 400 that may work in system 100
and may include an Evolved-Universal Terrestrial Radio Access
Network (E-UTRAN) 405. The E-UTRAN 405 includes several evolved
Node-Bs, (eNBs) 420. The WTRU 410 is in communication with an eNB
420. The eNBs 420 interface with each other using an X2 interface.
Each of the eNBs 420 interface with a Mobility Management Entity
(MME)/Serving GateWay (S-GW) 430 through an S1 interface. Although
a single WTRU 410 and three eNBs 420 are shown in FIG. 4, it should
be apparent that any combination of wireless and wired devices may
be included in the wireless communication system access network
400.
[0034] FIG. 5 is an example block diagram of an LTE wireless
communication system 500 including the WTRU 410, the eNB 420, and
the MME/S-GW 430. As shown in FIG. 5, the WTRU 410, the eNB 420 and
the MME/S-GW 430 are configured to detect HNBs, detect entering or
leaving the vicinity/proximity of a HNB, receive configuration
information that may include gaps, measure at least one frequency
or RAT with respect to the HNB and release measurement
configurations that may include gaps with respect to a WTRU
entering or exiting the vicinity/proximity of a HNB cell.
[0035] In addition to the components that may be found in a typical
WTRU, the WTRU 410 includes a processor 516 with an optional linked
memory 522, at least one transceiver 514, an optional battery 520,
and an antenna 518. The processor 516 is configured to detect HNBs,
detect entering or leaving the vicinity/proximity of a HNB, receive
configuration information that may include gaps, measure at least
one frequency or RAT with respect to the HNB and release
measurement configurations that may include gaps with respect to a
WTRU entering or exiting the vicinity/proximity of a HNB cell. The
transceiver 514 is in communication with the processor 516 and the
antenna 518 to facilitate the transmission and reception of
wireless communications. In case a battery 520 is used in the WTRU
410, it powers the transceiver 514 and the processor 516.
[0036] In addition to the components that may be found in a typical
eNB, the eNB 420 includes a processor 517 with an optional linked
memory 515, transceivers 519, and antennas 521. The processor 517
is configured to detect HNBs, detect entering or leaving the
vicinity/proximity of a HNB, receive configuration information that
may include gaps, measure at least one frequency or RAT with
respect to the HNB and release measurement configurations that may
include gaps with respect to a WTRU entering or exiting the
vicinity/proximity of a HNB cell. The transceivers 519 are in
communication with the processor 517 and antennas 521 to facilitate
the transmission and reception of wireless communications. The eNB
520 is connected to the Mobility Management Entity/Serving GateWay
(MME/S-GW) 530 which includes a processor 533 with an optional
linked memory 534.
[0037] FIG. 6 is an example block diagram of a WTRU 600 that is
configured according to the embodiments disclosed herein. In
addition to the components that may be found in a typical WTRU, the
WTRU 600 includes an antenna 605, a transmitter 610, a receiver
615, a processor 620 and a universal subscriber identity module
(USIM) (or LTE equivalent) 625. The receiver 615 is configured to
receive a broadcast via the antenna 605 from a cell including a
cell ID. The processor 620 is electrically coupled to the
transmitter 610, the receiver 615 and the USIM (or LTE equivalent)
625. The processor 620 is configured to detect HNBs, detect
entering or leaving the vicinity/proximity of a HNB, receive
configuration information that may include gaps, measure at least
one frequency or RAT with respect to the HNB and release
measurement configurations that may include gaps with respect to a
WTRU entering or exiting the vicinity/proximity of a HNB cell.
[0038] Various embodiments are described herein to detect HNBs,
receive configuration information, measure at least one frequency
or RAT with respect to the HNB and release measurement
configurations that may include gaps with respect to a WTRU
entering or exiting a HNB cell. Such embodiments may include, for
example, methods that the WTRU may use to request a measurement
configuration that may include a request for an allocation of gaps
so that it may detect the PSC or PCI of an HNB in its neighborhood
and/or measure its PSC or PCI on other frequencies. Embodiments for
releasing the measurement configuration in addition to any gaps are
also provided.
[0039] With respect to the various embodiments, two different
scenarios may be considered. In a first scenario, the WTRU visits a
certain HNB for the first time. In a second scenario, the WTRU
subsequently encounters the same HNB (after the initial encounter).
In the second scenario, the WTRU has already stored fingerprint
information identifying the approximate location of an allowed HNB
(e.g. a CSG that is in the whitelist of the WTRU) and may use it to
determine if the WTRU is in the vicinity of an allowed HNB. Based
on the outcome of the determination, the WTRU may know whether to
measure at least one frequency or RAT. The terms vicinity and
proximity may be used interchangeably herein.
[0040] In one embodiment, when such a determination is made, the
WTRU may send a request (e.g., a report) to the network notifying
the network of the vicinity of this HNB. This may be use to send a
request (e.g., a report) to the network to perform measurements of
CSG cells in the neighborhood or in the vicinity of a given
frequency or RAT. In order to allow the WTRU to request such
measurement configurations, new measurement report types (such as
for inter-frequency or inter-RAT) or events may be introduced. In
one option, the WTRU may introduce two events. One example of an
event or measurement type may, for example, be for the first
scenario where the WTRU is in the vicinity of an inter-frequency
HNB for the first time and, as a consequence, does not have a
stored fingerprint for the HNB. Another example event or type may,
for example, be for the second scenario, where the WTRU is aware
that an allowed neighboring HNB is present in a frequency or RAT
due to stored fingerprint information.
[0041] For instance, in the first scenario, where the WTRU does not
have the capability to determine whether it is within the coverage
of an allowed HNB or not, the WTRU may introduce a new event or
report with the description "Request for gaps for detecting
inter-frequency HNBs." For example, in UMTS, this event may be
called event 2g. For LTE, the event may be called event A6.
Although this event is referred to as event 2g or A6, it may take
any other number, name or type. Although the term "Request for gaps
. . . " is used in the example, it may alternatively be a "Request
for measurement configuration . . . " or "Request for measurement
configuration and gaps . . . ."
[0042] This new event/report may be triggered as a result of the
initiation of a manual HNB search, which may now be allowed in
connected mode. Because the WTRU is in connected mode (e.g.,
CELL_DCH), it cannot measure a frequency without service
interruption. Therefore, once a manual search is initiated, the
WTRU may trigger event 2g to indicate to the network that it would
like to measure an HNB frequency Of the network had previously
configured the WTRU with a measurement command for this event). The
network may then configure the WTRU with gaps, and, accordingly,
the WTRU may detect the HNB PSC (or PCI) on at least one frequency
(if any are available). Although the CELL_DCH is shown as an
illustrative state, the methods and apparatus described herein are
also applicable to WTRUs in the CELL_FACH state.
[0043] The event 2g may be triggered in other ways in addition to
being triggered by a manual search. For example, the event 2g may
also be triggered by a location-type detection when the WTRU is
equipped with a GPS. For example, if the WTRU detects that it
entered a city area (or any specific preferred HNB area); it may
send an event 2g to the network. Otherwise, no event is triggered.
By way of another example, the event 2g may be triggered by a
periodic search for HNBs defined in the WTRU (e.g., upon expiration
of a timer). The duration of this timer may be fixed or
configurable by the network or a user. According to this example,
once the timer expires, the WTRU is triggered to perform an HNB
search in the current frequency (and, optionally, in at least one
frequency and system). The event for requesting gaps may also be
triggered if the WTRU detects that a desired PSC or PCI (or
alternatively HNB) is in a neighboring list provided to the
WTRU.
[0044] It may also be possible for the WTRU to perform measurements
on the HNB frequency without using any measurement or compressed
mode gap. This may occur when, for example, the WTRU is configured
with Continuous Packet Connectivity (CPC) Discontinuous reception
(DRX) (for UMTS) in CELL_DCH or with DRX in LTE and there is little
traffic activity. In this example embodiment, event 2f or 2g may
optionally be triggered only if the WTRU does not detect the PSC or
PCI of the HNB after a timer expires (e.g., the timer may have been
started responsive to the manual search request or detection of a
matching fingerprint). Such a timer may be stopped if/when the WTRU
detects the PSC or PCI of the HNB (e.g., due to DRX opportunities).
In another option, the timer may also be stopped after a
pre-defined or pre-signaled inter-frequency measurement duration
(performed during DRX opportunities) has elapsed.
[0045] Optionally, as part of the new measurement event, the WTRU
may indicate the reason why it was triggered, such as manual
search, periodic search by the WTRU, location and the PSC/PSI in
neighboring list. The neighboring list may be provided by the
network and includes the PSCs/PSIs of the cells located in the
neighborhood of the WTRU. As stated above, the whitelist may
contain the CSG IDs of the HNBs the WTRU may be allowed to access.
A neighbor cell may or may not have its CSG ID as part of the WTRU
whitelist.
[0046] In the second scenario, if the WTRU detects, using stored
fingerprint information, that at least one of the HNBs with a CSG
ID stored in its Universal Subscriber Identity Module (USIM) or
whitelist may potentially be using a same of different frequency or
different RAT than the serving macro cell and is close to its
current location (in the proximity of the macro cell), the WTRU may
introduce, trigger and send to the network a new
event/report/message indicating that a CSG is in the proximity
(e.g., the WTRU is entering an area in which a CSG whose CSG
identity is in the WTRU's whitelist may be available). Upon
reception of this report, the network may configure the WTRU for
measurements, optionally using gaps, so that the WTRU may measure
the PSCs or PCIs corresponding to the HNBs on the applicable
frequency(ies).
[0047] The new report may correspond to a new event within an
existing measurement type (e.g., inter-frequency type, group 2x or
Ax) and may be called, for example, event 2h for UMTS and A7 for
LTE and may be entitled "One or several HNBs on a different
frequency match the current WTRU location." Alternatively, the same
event/report may be used for both the first and second scenarios
described above. The event may, for instance, be consolidated in
one event (e.g., event 2g for UMTS and A6 for LTE). The event may
be triggered based on any of the individual or combined conditions
described above.
[0048] In another embodiment, the WTRU may use an existing event to
report a preference to measure a neighboring HNB in a frequency,
even if the estimated quality of the currently used frequency is
above a certain threshold. This may be achieved for UMTS, for
example, by extending an existing event, such as event 2f.
Extending the event may be performed, for example, by adding a one
bit information element (IE) (such as a flag) indicating that the
event was triggered for HNB and that the WTRU may like to measure
an HNB on a different frequency or system. For UMTS, the additional
IE may be added in any IE, such as measurement report structures,
event results, Inter-Frequency event results and extensions to
sub-IEs containing event 2f information. For LTE, the additional IE
may be added, for example, as a non-critical extension of the
MeasurementReport message or of the measResults IE.
[0049] In another embodiment, the WTRU may use a new type of
measurement group to notify the network about HNB related events as
described herein. These HNB events within a new measurement type
may, for example, be referred/configured as measurement type 8, and
be referred to as CSG reporting type. For example, 8x events for
UMTS and Cx events for LTE may be defined. These new measurement
types may be used for frequency or RAT measurements. For example,
the WTRU may use new event 8a ("request of gaps for detecting
inter-frequency PSC) to request gaps. Alternatively, the WTRU may
introduce two new events such as, for example, 8a and 8b. One of
the new events may be used for the first scenario where the WTRU
has no fingerprint information, and the other may be used for the
second scenario where the WTRU has fingerprint information (similar
to 2g and 2h, for example). Two separate events may be defined for
inter-frequency and inter-RAT requests for PSC detection.
Alternatively, one event or measurement type may be used for both
frequency and RAT requests. This common measurement type is used by
the WTRU to report to the network that it has detected that an
allowed CSG is in the vicinity of the current location.
[0050] Alternatively, a new Radio Resource Control (RRC) message
may be defined via which the WTRU may use to report CSGs in the
vicinity. This new message may carry the same information described
above for the other embodiments.
[0051] While the above embodiments are described in the context of
inter-frequency measurements, they are equally applicable for
requesting gaps to detect HNBs for the inter-RAT scenarios as well
(e.g., if the WTRU attempts to measure and handover from a UMTS
macro cell to an LTE HeNB) and intra-frequency scenarios. It should
also be understood that the triggering criteria may be similar to
the inter-frequency scenario. In the inter-RAT case, a new
inter-RAT event may be added (e.g., event 3e for UMTS and B3 for
LTE, "Request of gaps for detecting HNBs on another system").
Alternatively, a new event from the new HNB events may be defined
(e.g., 8x for UMTS or Cx for LTE, "Request of gaps for detecting
other system's HNBs"). An existing 3x event may alternatively be
reused as described herein.
[0052] The new event/report as part of the new measurement type, 8
may be the same one used for the inter-frequency case. For example,
one event 8a or one report may be used for "Request of gaps for
detecting HNBs" or (using the same terminology as above), "One or
several HNBs match the current WTRU location". In this case, once
the event/report is triggered, it may also contain an optional
information element indicating whether the WTRU wishes to perform
measurements on inter-frequency, inter-RAT, or both.
[0053] In general, the network may use the information provided by
the WTRU to determine whether measurement configurations that may
include gaps should be allocated and also the duration of the gaps,
if needed. The duration of the gaps, for example, may depend on the
number of frequencies the WTRU has to measure.
[0054] Optionally, a new IE may be added in the report to indicate
the reason why the event report was triggered. This may include, by
way of non-limiting example, one, or a combination of, a manual
search, a periodic search by the WTRU, a location, a fingerprint
matches the fingerprint of at least one HNB stored in the WTRU
whitelist, and a PSC is in a neighbor list. This may be combined
with any of the embodiments described herein.
[0055] In another embodiment for triggering proximity indication
reporting, a LTE macro cell connection may have a higher priority
than the UMTS HNB. Although described with respect to a LTE macro
cell and an UMTS HNB, the description herein is applicable to other
RAT combinations of macro cells and HNBs. In this embodiment, if a
WTRU is connected to a LTE macro cell and it detects by means of
its stored fingerprint information that it is close to a UMTS HNB
that it is a member of, the WTRU does not necessarily trigger an
autonomous search, (i.e., it does not send a HNB proximity
indication to the network). The autonomous search may be initiated
in such circumstances, only if the LTE macro cell channel
conditions are deteriorating (i.e. the channel quality falls below
a given threshold). The conditions to trigger a search and a
measurement report to indicate a proximity indication may occur if
1) the current macro serving cell is LTE; 2) one of the WTRUs
stored fingerprints matches a UMTS HNB (i.e., a UMTS HNB is in the
WTRU's proximity); and 3) the macro serving cell quality is below a
certain threshold. This threshold may be configured by the network,
may be a fixed value used by the WTRU or may be determined by the
WTRU. It may be a common value or a value per cell.
[0056] If these conditions are met, then the WTRU may send a
measurement report to the network in order to request a measurement
configuration that may include gaps for detecting the PSC and
acquiring a master information block (MIB) (with optionally a
Scheduling Block and a system information block 3 (SIB3) of the
UMTS HNB. If conditions 1 and 2 are fulfilled and condition 3 is
not, the WTRU may not send any report to the network to trigger the
HNB measurements.
[0057] Optionally, the WTRU may still autonomously measure the
channel quality of the PSC of the UMTS HNB that is in the WTRU's
proximity and trigger the search if the PSC of the UMTS HNB is
above a threshold. This option may be for a configured period of
time. This trigger may be used in combination with the other
triggers described herein.
[0058] Described now are examples for the information contained in
the report.
[0059] Optionally, as part of the report, additional information
may be reported to the network (if available to the WTRU),
including, by way of non-limiting example, one, or a combination
of, the known frequency of the HNB(s) which triggered the proximity
report and whose CSG is stored on the whitelist of the WTRU, and/or
the known RAT of the CSG(s) cell which triggered the report (e.g.,
LTE or UMTS).
[0060] The WTRU may optionally also include the following
information pertaining to the CSG(s) which triggered the report
such as, the known HNB's PSCs/PSIs of the CSG(s) cells stored on
the whitelist of the WTRU, and the WTRU CSG IDs part of the
whitelist. The WTRU may also include a CGI in the report sent to
the network. Such additional information may be useful to the WTRU
for detecting a "false" fingerprint match (e.g., where the WTRU
determines that an HNB included in its whitelist is in its
vicinity, but this is not actually the case). In this example, if
the eNB or RNC receives a CGI in the gap request report, it may
verify that an HNB with the corresponding CGI actually exists. If,
however, it does not recognize the CGI, the eNB or RNC may decide
to not configure the WTRU with a measurement configuration.
Accordingly, if the WTRU does not receive a gaps configuration (or
other measurement configuration) from the network within a certain
period of time after requesting the network to configure it for
measurement and/or gaps, the WTRU may decide to delete the
corresponding fingerprint from its memory to avoid unnecessary gaps
requests in the future. Alternatively, or in addition, the network
(e.g., the eNB or the RNC) may explicitly indicate to the WTRU that
a cell having a CGI corresponding to the CGI that the WTRU reported
does not exist. Using this information, the WTRU may then delete
the corresponding fingerprint as in the previous example. The
network may also use the CSG ID information (if provided by the
WTRU) for a similar purpose.
[0061] Optionally, in a deployment where the network is aware of
all CSG cell frequencies in the vicinity and realizes that no CSG
cell corresponding to the CSG cell reported by the WTRU as part of
its whitelist is available, the network may not allocate any gaps.
Instead, the network may, optionally, send an RRC message (for
example, a measurement control) back to the WTRU indicating that no
such CSG cell is available and that the WTRU does not have to
measure inter-frequency HNBs. The WTRU may then update its HNB
fingerprints accordingly.
[0062] Optionally, together with the proximity indicator, the WTRU
may signal that a given HNB that is in the WTRU's proximity has
priority. This may assist the network in allowing the WTRU to
measure the HNB and potentially providing a measurement
configuration that may include gaps.
[0063] The network may need to explicitly release measurement
configurations or gaps that it allocated to allow the WTRU to
detect HNB PSCs/PCIs on a frequency or RAT in case, for example, no
handover occurs. Different causes may trigger the
interruption/release of the measurement configuration which may
have included gaps, such as, for example: the WTRU did not detect
(and therefore did not report to the network) an HNB PSC after a
certain period of time; the quality of the detected HNBs in a
frequency or other system is below a certain threshold; the WTRU
only detected HNB PSCs that are not on its whitelist; the WTRU
detected that it is leaving the vicinity of its allowed HNBs (e.g.,
a HNB whose CSG is in the WTRU's whitelist) using its stored HNB
fingerprints (e.g., there is no longer a matching fingerprint); the
WTRU measured, but did not find, any HNBs with the CSG IDs in its
whitelist; and no acceptable HNBs were detected.
[0064] The network or the WTRU may trigger release of the gaps. For
example, if the network does not receive any HNB PSCs reported by
the WTRU after a certain period of time, it may reconfigure the
WTRU for deactivating the gaps. Alternatively, if the network knows
the WTRU's location and realizes that no inter-frequency HNB is
located in the WTRU's neighborhood, it may also release the gaps in
the WTRU. The WTRU may release the gaps according to any of the
following embodiments.
[0065] In one embodiment, the WTRU may notify the network that it
no longer requires a measurement configuration (e.g., notify the
network that it is leaving the area where there might be an allowed
CSG cell). Upon reception of this notification, the network may
reconfigure the WTRU to remove the measurement configuration, and
optionally the gaps for the WTRU. When referred to hereafter,
releasing the gaps refers to releasing the measurement
configuration for CSG cells, or removing the configuration.
[0066] This notification/report may be sent via a new
inter-frequency event. For example, for UMTS it may be type 2i,
"Request for releasing the gaps allocated for detecting
inter-frequency HNB".
[0067] Alternatively, the WTRU may use the new measurement type for
CSG reports, e.g., 8. A new event/cause for reporting this event
may be defined. As an example this may be called event 8b (or C2)
"Request for releasing gaps for detecting inter-frequency HNB," to
ask the network to release gaps (e.g., 8x for UMTS or Cx for LTE as
described in the previous section). It is understood that the
naming of events/trigger causes are illustrative and any names or
descriptors may be used. For example, when the trigger corresponds
to "the WTRU detected that it is leaving the vicinity of its
allowed HNBs (e.g., a HNB whose CSG is in the WTRU's whitelist)",
then the WTRU cause may be referred to as "the WTRU is leaving the
CSG area".
[0068] In another embodiment, the WTRU may release the gaps
autonomously, without waiting for a reconfiguration message from
the network after it detects that it no longer needs to measure
inter-frequency HNBs. The WTRU may also notify the network that it
has released the gaps with a new event, such as event 2j fro UMTS,
"Gaps allocated for detecting inter-frequency HNB have been
released." Alternatively, the WTRU may use an HNB event type, for
example, 8x for UMTS or Cx for LTE, as described herein. The new
event may be called, for example, 8c (or C3) "Gaps for detecting
inter-frequency PSC have been released."
[0069] In another embodiment, the WTRU may re-use an existing
measurement report event type and add to it a new IE to inform the
network that the gaps previously allocated for detecting HNBs on
other frequencies have to be released. Alternatively, this new IE
may indicate to the network that the WTRU has autonomously released
its gaps. For example, for UMTS, the event 2f may be modified as
such with a new optional IE of type enumeration indicating one of a
request for releasing gaps allocated for detecting inter-frequency
HNB or a notification that the WTRU has released the gaps allocated
for detecting inter-frequency HNB.
[0070] The WTRU may add an IE in the measurement report describing
why it released the gaps. The IE may indicate, for example, that
the Inter-frequency HNB search timer has elapsed or that the stored
HNB fingerprint does not match.
[0071] Alternatively, a new RRC message may be defined and used by
the WTRU to request or notify the network that one of the triggers
described above has been met. For the trigger, wherein the WTRU
detected that it is leaving the vicinity of its allowed HNBs (e.g.,
a HNB whose CSG is in the WTRU's whitelist), the new RRC message
used indicates to the network that the WTRU is leaving the area.
This new message may carry the same information as described above
for the other embodiments. This RRC message may be a new message or
the same RRC message used to indicate the request for initial
measurements (e.g. when the WTRU enters the vicinity of a CSG
cell).
[0072] The embodiments described herein for releasing the
measurement configuration and any gaps previously allocated for
detecting inter-frequency HNBs, may also be used for the inter-RAT
(IRAT) scenario as well. For example, the WTRU may try to handover
from a UMTS macro cell to an LTE HeNB. In the IRAT case, a new IRAT
event may be added. For instance, event 3f for UMTS and event B4
for LTE, "Request for releasing gaps allocated for detecting HNBs
of other system," may be added or a new event from the new HNB
events 8c "Request for releasing gaps allocated for measuring other
system" may be defined. Alternatively, a common event may be used
as 8x (e.g., 8b) to notify the network that the measurement
configuration and any gaps may no longer be needed. The common
event may be used for both inter-frequency and inter-RAT
measurement configuration and gap release when a WTRU leaves a HNB
cell.
[0073] Optionally, the gaps may also be released once a handover to
a HNB occurs.
[0074] Although the CELL_DCH is shown as an illustrative state, the
methods and apparatus described herein are also applicable to WTRUs
in the CELL_FACH state. In other connected mode states, such as
CELL_FACH states, similar messages as the ones described for
CELL_DCH may be used to notify the network.
[0075] It is understood that these methods are also applicable to
other connected mode states such as CELL_FACH, even though CELL_DCH
messages are shown above as illustrative states. The messages used
to notify the network as described herein for CELL_FACH state may
be similar to the ones described above or optionally, in the
CELL_FACH state the WTRU may use messages such as CELL UPDATE to
notify the network. A new cause or information element may be used
by the WTRU to indicate the reason why a CELL UPDATE Message is
being sent (e.g., entering or leaving the vicinity of a HNB).
[0076] One or a combination of the following example methods may be
implemented in order to prevent the WTRU from requesting gaps too
frequently.
[0077] In an example method, the WTRU may not be allowed to request
gaps for detecting HNB PSC/PCI more than a certain number of times
during a certain period of time. The periodicity (e.g., number of
times and period of time) may be signaled by the network, may be
part of the broadcast information, or stored in the WTRU.
Optionally, this periodicity may differ per HNB. For example, the
periodicity may be high for the user's home HNB, while low for
other HNBs. This periodicity may also depend on the user's
mobility.
[0078] In another example method, the network may be aware that
there are no HNBs in the WTRU's vicinity and may indicate to the
WTRU in an existing signal (e.g. new IE added in measurement
control) that it is not allowed to request gaps (or triggering
proximity reports) for detecting an HNB PSC/PCI.
[0079] In another example method, the network may indicate to the
WTRU in an existing signal that only gap requests based on
fingerprint matches are allowed and that periodic requests are
forbidden.
[0080] In another example method, the fingerprint information in
the WTRU may be maintained to make sure it is valid when the WTRU
uses it to request gaps (i.e., to make sure there is an allowed HNB
in the WTRU's neighborhood). This may be implemented using one or a
combination of the following methods.
[0081] In one example implementation, a validity timer per HNB
fingerprint may be started when the fingerprint is stored in the
WTRU. When this timer expires the WTRU may delete the fingerprint
associated to the HNB.
[0082] In another example implementation, a periodic timer may be
used to delete periodically all the HNB fingerprints stored in the
WTRU.
[0083] In another example implementation, the network may request
the WTRU to delete one or a list of all the HNB fingerprints the
WTRU has stored by sending an RRC message to the WTRU.
[0084] In another example implementation, in case the handover to a
particular HNB is rejected by the network, the WTRU may delete the
associated fingerprint.
[0085] Described herein are embodiments for HNB PSC detection via
transmission. In one embodiment, the inter-frequency PSC (or PCI)
detection may be performed via the HNBs' transmissions of the
common pilot channel (CPICH) on the serving macro cell frequency
(or transmission of primary and secondary synchronization signals
(PSS and SSS) for LTE). In this embodiment, only the CPICH (for
UMTS) or PSS/SSS (for LTE) is transmitted, without any of the
System Information Blocks (SIBs). The signals necessary to detect a
PSC or PCI (CPICH for UMTS, PSS/SSS for LTE) are transmitted by the
HNB on the serving macro cell frequency. Optionally, in addition to
the CPICH, the master information block (MIB) indicating the
frequency of the HNB and that the cell is a HNB cell may be
broadcast. The WTRU performing intra-frequency measurements may
detect the PSCs and, therefore, may request gaps from the network
to perform additional measurements on the HNB's corresponding
frequency (if known from signaling from the macro cell or otherwise
indicated). If it is not known from the macro cell's signaling or
from other indications, the WTRU may have to rely on fingerprint
information or even measure on all other frequencies.
[0086] The gaps may be requested on one, or a combination of, the
following conditions: the WTRU detects HNB's PSCs (or PCIs); the
WTRU detects an HNB PSC (or PCI) that is in its whitelist; the WTRU
detects an HNB PSC (or PCI) that is contained within a known
fingerprint location; the WTRU performs a manual search and detects
that there are HNBs in the neighboring frequencies; the WTRU
performs a periodic search; the WTRU detects an HNB PSC (or PCI)
that is in a reserved PSC or PCI range of hybrid cells; and the
WTRU detects an HNB PSC (or PCI) that is in a reserved PSC range or
PCI range of CSG cells.
[0087] Signaling of supported HNB PSC/PCI detection methods on
inbound mobility support are disclosed hereinafter.
[0088] The different HNB PSC/PCI detection methods disclosed herein
may be fully or only partially supported by the WTRU. The WTRU may
indicate to the network which methods it supports by adding new IEs
in existing RRC messages (for example, in the RRC Connection
Request or the RRC Connection Setup Complete) or in a new RRC
message. One or a combination of the following capabilities may be
indicated by the WTRU to the network: a) WTRU capable to request
for gaps for detecting HNB PSC/PCI on a frequency (e.g. inter or
intra-frequency to the same RAT as the macro cell); b) WTRU capable
to request for gaps for detecting HNB PSC/PCI in a different RAT;
and c) WTRU capable to detect PSC/PCI of inter-frequency HNB
transmitting their CPICH for UMTS or PSS/SSS for LTE on the serving
macro-cell frequency. As described above, requesting gaps may
correspond to the capability of detecting that you are in the
vicinity or proximity of a CSG cell whose CSG belongs to the WTRU's
whitelist.
[0089] In addition, the network may deactivate any of the supported
methods mentioned hereinabove in the WTRU by explicit
signaling.
[0090] Even if the WTRU supports the above mentioned capabilities,
the network also needs to support this mobility procedure. In
general, the WTRU and network both need to support mobility in the
case where a WTRU enters or exits the vicinity or proximity of a
HNB. As described herein, the WTRU may request or enable the
detection and triggering of requests for measurement configurations
and any gaps or trigger events if the WTRU knows that the network
supports inbound mobility and the WTRU also supports it.
[0091] In order to determine that the network supports inbound
mobility and more specifically the triggers described above, one or
a combination of the following methods may be used. For
illustrative purposes, inbound mobility may refer to the ability to
detect proximity to a HNB and to send/receive reports/events in
response to the proximity detection, for example, when the WTRU
enters/exits the vicinity (proximity) of the HNB. In one example
method, the events to trigger detection mechanisms for inbound
mobility are configured by the network via measurement
control/configuration messages. If such measurement types or events
are not configured (e.g., not present in the configuration
messages), the WTRU determines that inbound mobility detection is
not supported. Depending on the measurements that are configured,
the WTRU implicitly determines whether inter-frequency, inter-RAT
or intra-frequency mobility is supported. For example, in the case
where a new measurement type, 8, is introduced as described above,
inter-frequency or intra-frequency CSG detection mechanisms can be
configured for a certain RAT. If not configured then the WTRU
determines that the network does not support inbound detection
mechanism for the given RAT and therefore disables the
functionality.
[0092] In another example method, the network explicitly signals to
the WTRU upon RRC connection procedures, that inbound mobility to
HNBs is supported. If the WTRU moves to an area where inbound
mobility is not supported, the network may inform the WTRU of the
change of capability.
[0093] In another example method, the network may explicitly
indicate whether inter-frequency inbound mobility is supported,
whether inter-RAT mobility is supported, or whether intra-frequency
inbound mobility is supported. In the case of inter-RAT mobility,
the network may also explicitly indicate whether just LTE to HNB
UMTS mobility is supported, UMTS to LTE HNB mobility is supported
or any inter-RAT mobility is supported.
[0094] Events similar to the ones described above may also be used,
wherein the WTRU may provide the network with any of the
information described above.
[0095] FIG. 7 illustrates a method 700 for implementing the
examples and embodiments described herein in the case of a WTRU
entering the cell or frequency of an HNB. Upon entering the cell or
frequency of the HNB, the WTRU and network perform a capability
exchange to determine if inbound mobility is supported by the WTRU
and network. The network may need to configure the WTRU with the
events that trigger the measurements. The WTRU detects via, for
example, fingerprint information that it has entered into the
vicinity of an HNB cell whose CSG ID is in the WTRU's whitelist
(705). The WTRU then indicates to the network that it has entered
the vicinity of a HNB whose CSG ID is in its whitelist (715). The
indication or request message may include HNB information, such as
the frequency or RAT for the HNB which triggered the report. The
indication or request message may be sent via a radio resource
control (RRC) message or a Measurement Report. The Measurement
Report may contain the proximity indication. The WTRU then receives
from the network, base station or other similar entity as
determined by system architecture or structure, a measurement
configuration message that may include gaps and the PSCs/PCIs to
measure (725) and performs the measurements to detect the PSC or
PCI (735). The WTRU may then send a measurement report to the base
station (745). The measurement report may include an Information
Element (IE) containing, for example, a detection result,
measurement results for the cells that are on the frequency added
by the measurement configuration and a triggering of an existing
mobility event such as, for example event type 1D or 1A.
[0096] FIG. 8 illustrates a method 800 for implementing the
examples and embodiments described herein in the case of a WTRU
exiting the cell or frequency of an HNB. As in FIG. 7, a capability
exchange may be performed between the WTRU and the network
including the sending of configuration information for the events
that trigger the measurements. Initially, the WTRU detects, via for
example, the use of fingerprint information, that it is exiting the
vicinity of an HNB cell whose CSG ID is in the WTRU's whitelist
(805). The WTRU then indicates to the network, base station or
similar entity that may be dependent on system, that it is leaving
the HNB area (e.g., that it may no longer need the measurement
configuration or gaps allocated to acquire the HNB's PSCs or PCIs)
(815). The indication or request message may be sent via a radio
resource control (RRC) message or a measurement report. The WTRU
then receives from the network, base station or similar entity that
may be dependent on system, a configuration message to release the
measurement configuration, which may have included gaps (825) and
the WTRU then releases the configuration (835).
[0097] Described herein are additional embodiments. In an example
embodiment, the WTRU may be configured for discontinuous reception
(DRX) and may have enough idle periods to detect the PSC and read
the system information of the HNB. The WTRU may start the handover
procedure evaluation if the macro cell quality is good. A limit on
the duration during which the WTRU tries to acquire the SIBs may be
applied in order to limit the power usage of the WTRU. For example,
the WTRU may stop the inter-RAT handover procedure when a timer
expires.
[0098] In another embodiment, in case event B1 is configured by the
network, where event B1 is "Inter-RAT neighbor becomes better than
threshold", the WTRU may not report or may not trigger the event in
case it is connected to, for example, a LTE macro cell, and the
inter-RAT neighbor cell that is becoming better than a threshold
is, for example, an UMTS HNB. In this instance, the LTE macro cell
may have a higher priority than the UMTS HNB. If the WTRU detects
that the PSC corresponds to a HNB, the WTRU may trigger the
measurement report indicating the event B1 and additionally signal
a proximity indication. The proximity indication may be added to
the same measurement report or to a different measurement report
that may be used to initiate autonomous search in the WTRU. As
indicated earlier, the roles of the specific RATs may be
interchanged in the examples and are used herein as illustrative
examples.
[0099] This new restriction about inbound mobility from the macro
LTE cell to an UMTS HNB, may prevent the user who owns a LTE
capable WTRU but has a UMTS HNB, to handover to the UMTS HNB if the
UMTS HNB is in the coverage of the LTE macro cell. One method for
connecting to the UMTS HNB would be to drop the connection to the
LTE macro cell so that the WTRU may camp on the UMTS HNB in Idle
mode. Alternatively, if the user wants to switch to the UMTS HNB
while in connected mode, an optional indicator may be added in the
fingerprint information stored for the UMTS HNB that would force
the WTRU to perform an inter-RAT handover or initiate an autonomous
search from a LTE macro cell to this particular UMTS HNB. For
instance, the flag in the fingerprint information may be used as an
absolute priority indicator for the UMTS HNB. In this instance, no
matter what RAT or frequency the WTRU is connected on, the HNB
takes priority over all the other macro cells and therefore an
autonomous search is triggered and the proximity indicator is
signaled to the network. Additional information may be added in the
proximity indication including the RAT and the priority associated
with the RAT.
[0100] In another example method, such inter-RAT autonomous search
or handover may also be initiated by the user using a manual search
even if the conditions described earlier to measure the HNB in the
other RAT have not been met. In such cases, if the WTRU detects
that a search has been initiated, and the WTRU has a stored HNB on
another RAT in its fingerprint information, the WTRU may
immediately attempt to decode the NB that is in its fingerprint
information. Optionally, the manual search by the user may trigger
the WTRU to decide that a proximity indication in a measurement
report may be sent to the network to initiate measurement and
detection of the HNB even if the conditions discussed above have
not been met. In this method, the manual trigger by the user may
overrule the set priorities between the RATs and HNBs.
[0101] In another example method, it may be specified that the WTRU
gives preference to a member HNB on a different RAT than the
serving macro cell. This preferential treatment may occur when the
HNB is using the same RAT as a reference HNB that may include, for
example, a HNB installed at a user's home or any HNB as indicated
by the user. The reference HNB may be indicated in the fingerprint
information stored in the WTRU. The rules for restricting the
inter-RAT inbound handover may include fulfilling the following
conditions: 1) current macro serving cell is on a different RAT
than a target HNB; 2) target HNB, using a different RAT than the
reference HNB, matches fingerprint information stored in the WTRU;
and 3) macro serving cell quality is below a certain threshold.
This threshold may be configured by the network, may be a fixed
value used by the WTRU or may be determined by the WTRU. The
threshold may be a common value or a value per cell. Optionally,
the conditions may need to persist for a given period of time.
[0102] If all three conditions are met, then the WTRU sends a
measurement report to the network in order to request a measurement
configuration that may include gaps for detecting the PSC/PCI,
acquiring the system information or to ask for the authorization to
use autonomous gaps. If only conditions 1 and 2 are met, the WTRU
may not send any report to the network to trigger the HNB
measurements. Alternatively, the WTRU may still send a measurement
report indicating that the proximity indication corresponds to a
HNB and may include in the measurement report the RAT of the HNB.
The network may chose to allow the WTRU to start searching and
measuring the HNB belonging to a RAT other than the macro serving
cell upon explicit indication from the network.
[0103] In another example method, priorities between the RATs and
HNBs may be explicitly set by the network. The network may
explicitly indicate to the WTRU that a LTE macro cell and/or LTE
HNB have priority over a UMTS HNB. The WTRU, therefore, may
initiate a UMTS HNB search (that is in its proximity) if the
quality of the LTE macro cell or LTE HNB goes below a threshold as
described above. Other examples may include a LTE HNB that may have
priority over a UMTS macro cell or vice versa.
[0104] Priority indication for mobility between a macro cell on one
RAT and a HNB in another RAT may be different than inter-RAT
priority for macro cell to macro cell mobility. For instance, even
if LTE has higher priority for inter-RAT macro cell to macro cell,
the same rules may not be applicable if a UMTS HNB is in its
vicinity. In such a case, either the UMTS HNB may have been
signaled to have higher priority or by implicit rule it has higher
priority. If no priority indication has been signaled for the HNB
in the other RAT, the WTRU may assume: 1) that the HNB has priority
as for normal inbound mobility cases; 2) that the HNB in the other
RAT will inherit the same inter-RAT mobility priorities as the ones
indicated for macro cell to macro cell rules; or 3) it will act
according to one of the rules described above. The HNB priority
setting described herein may also be applicable for HNB to macro
cell priorities within the same frequency.
[0105] The inbound HNB priority indication (which may be applicable
to frequency or RAT) may be set for all CSGs belonging to a RAT or
frequency or may be set on a per CSG basis. Upon successful
registration, the priorities of the CSG and the RAT may be set and
optionally updated later. For instance, for some CSGs (e.g., the
user's home CSG), the network may prefer that the WTRU try to
connect to this CSG even if the WTRU is camped/connected to the
other frequency or RAT. However, for some CSGs the network may
prefer that the WTRU does not connect to this CSG (i.e., only
connects if the quality of the current macro cell is below a
threshold).
[0106] Alternatively, absolute HNB RAT priorities and optionally
absolute frequency priorities may be signaled. For instance, the
network may assign different RAT priorities. For example, if the
detected HNB has a HNB RAT priority higher than the RAT or
frequency the WTRU is connected to, the WTRU may initiate an
autonomous search in an effort to connect to this HNB. If the
detected HNB is in a lower priority HNB RAT, it may start
autonomous search if the quality of the current RAT or frequency is
below a threshold. The thresholds described in this disclosure for
the current connected RAT, may be similar to thresholds used for
normal inter-RAT mobility or alternatively HNB specific thresholds
which may be less strict and may allow the WTRU to connect to the
HNB earlier. The priorities may be indicated by signaling or in the
broadcasted system information.
[0107] In general, when a HNB in the WTRU's proximity has a higher
priority than the current macro cell (according to priorities set
with respect to any frequency and/or RAT as described above), the
WTRU may initiate an autonomous search (e.g. try to perform a
handover to this HNB). The autonomous search, for example, may
comprise the transmission of a measurement report and/or proximity
indication to the network and/or attempt to read SI. If this HNB
has a lower priority than the current RAT, an autonomous search may
be triggered if the quality of current macro cell is below a
threshold and optionally, if the quality is below a threshold for a
configured amount of time. This criteria is similar to the criteria
described above for fixed priority settings.
[0108] In certain situations, there may be an abundance of
opportunities for inter-RAT inbound handover attempts. For example,
users may purchase a HNB for one RAT and then upgrade to another
HNB with a different RAT. In other situations, they may have WTRUs
for one RAT and a HNB on another RAT and then decide to buy the HNB
of the same technology as the WTRU. In addition, some WTRUs may be
multiple RAT capable while other WTRUs may be single RAT. These
situations may lead to many inter-RAT inbound handover attempts by
the WTRU. This may be undesirable due to excessive battery usage
and service degradation. In order to limit the number of handover
evaluation procedures when the user is a macro cell coverage and
moves between HNBs of different RATs, the WTRU may use a special
CSG-inter-RAT Time to Trigger longer than the timer configured by
the network. Alternatively, there may be a CSG inter-RAT offset
added to the configured time to trigger. In these cases, when a
fingerprint match occurs the event report is therefore not
triggered too quickly. Since most HNBs are deployed for service
enhancement purposes, it is acceptable that the WTRU stays
connected on the macro cell for a longer period of time in order to
limit unnecessary inter-RAT inbound handovers. For example, if the
following conditions are fulfilled: 1) the WTRU is connected to a
macro cell of a certain RAT; 2) the WTRU detects a fingerprint
match for a HNB of a different RAT; and 3) the WTRU verifies that
the HNB quality is above a certain CSG-inter-RAT threshold during
the CSG-inter-RAT Time To Trigger duration, then the WTRU may
report a measurement event for this HNB to the network.
[0109] If conditions 1 and 2 are met but condition 3 is not met and
if the quality of the macro serving cell is not acceptable (e.g.,
below a certain threshold), the WTRU may also report a measurement
event for this HNB to the network. Otherwise the WTRU does not send
a measurement report and remains connected to the macro serving
cell.
[0110] The CSG-inter-RAT Time to Trigger may be used by the WTRU
when evaluating inter-RAT events B1, B2 for LTE, 3A, 3C events for
UMTS, or new events specified for HNB. The CSG-inter-RAT threshold
may be configured by the network, but may also be a threshold
determined by the WTRU so that the WTRU may give a certain
preference to member HNBs.
[0111] Alternatively, condition 3 may be deleted and condition 2
may be replaced by an alternative condition 2, where the WTRU may
detect a fingerprint match for a HNB on a different RAT and this
fingerprint match is verified during the CSG-inter-RAT Time To
Trigger duration. In this alternative, there may not be any
condition on the HNB signal quality, but it is assumed that in case
of a fingerprint match the quality of the HNB should be good.
[0112] In another implementation, it may be specified that the WTRU
has to stay connected to the macro serving cell for a certain
period of time before it may trigger an event to start the
inter-RAT HNB handover measurements. The timer duration may be
signaled by the network, or may be a pre-determined value known by
the WTRU. It may also be a value stored in the fingerprint
information per HNB so that the WTRU may be handed over to certain
HNBs faster than for others. If the timer has not expired yet, but
the serving macro cell quality is not acceptable anymore (e.g.,
below a certain threshold), the WTRU may be allowed to trigger an
event to start the handover measurements for the HNB in case there
is no other neighbor macro cell with good quality available. For
example, it may be decided that handovers from UMTS macro cells to
LTE HNBs may occur faster than handovers from LTE macro cells to
UMTS HNBs.
[0113] In order for the WTRU to build its fingerprint information
list for other RAT HNBs in Idle mode, the WTRU needs to be aware of
the PCI/PSC split for CSG cells of other RATs. For example, the
UMTS PSC split may be broadcast in the LTE system information while
the LTE PCI split may be broadcast in the UMTS system information.
The LTE SIB4 may be enhanced with a new IE umts-csg-PSC-Range while
the UMTS SIB11bis may be enhanced with a new IE "LTE CSG PCI Split
information". This inter-RAT HNB split information may also be
added in other existing SIBs or in new SIBs. This allows the WTRU,
during an autonomous search or a manual search, to recognize which
detected PSC/PCI belongs to other RATs CSG cells. When storing the
fingerprint information, the WTRU may also store the type of RAT of
the CSG cell (e.g., LTE or UMTS) so that once the WTRU is in
connected mode; the WTRU may apply the rules defined for inter-RAT
inbound mobility as described herein. Alternatively, the PSC/PCI
splits for the other technology may be sent to the WTRU via
dedicated RRC signaling, (e.g., measurement control). The network
may provide the PSC/PCI split for the other RAT periodically, or
the reporting may be started by one or a combination of the
following triggers including: 1) the macro serving cell
measurements reported by the WTRU to the network to show that the
macro serving cell quality is deteriorating (e.g., is below a
certain threshold); 2) the user activity is increasing leading to a
demand of higher data rates; and 3) the network detects that the
WTRU is in a neighborhood where only HNBs of a different RAT than
the macro serving cell are available or just a few HNBs of the same
RAT than the current macro serving cell are available.
[0114] Although features and elements are described above in
particular combinations, each feature or element can be used alone
without the other features and elements or in various combinations
with or without other features and elements. The methods or flow
charts provided herein may be implemented in a computer program,
software, or firmware incorporated in a computer-readable storage
medium for execution by a general purpose computer or a processor.
Examples of computer-readable storage mediums include 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).
[0115] Suitable processors include, by way of example, 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 Arrays (FPGAs)
circuits, any other type of integrated circuit (IC), and/or a state
machine.
[0116] A processor in association with software may be used to
implement a radio frequency transceiver for use in a wireless
transmit receive unit (WTRU), user equipment (UE), terminal, base
station, radio network controller (RNC), or any host computer. The
WTRU may be used in conjunction with modules, implemented in
hardware and/or software, such as a camera, a video camera module,
a videophone, a speakerphone, a vibration device, a speaker, a
microphone, a television transceiver, a hands free headset, a
keyboard, a Bluetooth.RTM. module, a frequency modulated (FM) radio
unit, a liquid crystal display (LCD) display unit, an organic
light-emitting diode (OLED) display unit, a digital music player, a
media player, a video game player module, an Internet browser,
and/or any wireless local area network (WLAN) or Ultra Wide Band
(UWB) module.
* * * * *