U.S. patent application number 15/386807 was filed with the patent office on 2017-04-27 for method and apparatus for supporting home node b services.
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 Christopher R. Cave, Rocco Di Girolamo, Paul Marinier, Diana Pani, Benoit Pelletier, Stephen E. Terry.
Application Number | 20170118702 15/386807 |
Document ID | / |
Family ID | 40352267 |
Filed Date | 2017-04-27 |
United States Patent
Application |
20170118702 |
Kind Code |
A1 |
Di Girolamo; Rocco ; et
al. |
April 27, 2017 |
METHOD AND APPARATUS FOR SUPPORTING HOME NODE B SERVICES
Abstract
A method and apparatus for supporting home Node B (HNB) services
are disclosed. A wireless transmit/receive unit (WTRU) receives HNB
access restriction information from an HNB and accesses the HNB if
an access to the HNB is allowed based on the HNB access restriction
information. The HNB access restriction information may be a closed
subscriber group identity (CSG ID), a status bit indicating whether
an HNB cell is available or not, an identity of WTRUs that are
allowed to access the HNB, information indicating whether an access
to a cell is barred or not. The WTRU may trigger measurements for
cell reselection even though signal strength on a currently
connected cell is above a threshold. The measurement may be
triggered manually, periodically, under the instruction from the
network, or based on a neighbor cell list including information
about HNB cells located nearby.
Inventors: |
Di Girolamo; Rocco; (Laval,
CA) ; Cave; Christopher R.; (Dollard-des-Ormeaux,
CA) ; Marinier; Paul; (Brossard, CA) ; Pani;
Diana; (Montreal, CA) ; Pelletier; Benoit;
(Roxboro, CA) ; Terry; Stephen E.; (Northport,
NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
InterDigital Patent Holdings, Inc. |
Wilmington |
DE |
US |
|
|
Assignee: |
InterDigital Patent Holdings,
Inc.
Wilmington
DE
|
Family ID: |
40352267 |
Appl. No.: |
15/386807 |
Filed: |
December 21, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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12239253 |
Sep 26, 2008 |
9572089 |
|
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15386807 |
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61048104 |
Apr 25, 2008 |
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60975835 |
Sep 28, 2007 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04J 11/0093 20130101;
H04W 84/045 20130101; H04W 48/16 20130101; H04W 48/12 20130101;
H04W 64/003 20130101 |
International
Class: |
H04W 48/16 20060101
H04W048/16; H04J 11/00 20060101 H04J011/00; H04W 64/00 20060101
H04W064/00; H04W 48/12 20060101 H04W048/12 |
Claims
1-72. (canceled)
73. A method comprising: a wireless transmit/receive unit (WTRU)
receiving an indication from a Node B that a cell is restricted,
wherein the indication is capable of being interpreted by the WTRU
and other WTRUs; the WTRU receiving a closed subscriber group (CSG)
broadcast that indicates that the cell is reserved for a CSG,
wherein the CSG broadcast is configured to be interpreted by the
WTRU, and wherein the CSG broadcast is configured to be unable to
be interpreted by the other WTRUs; the WTRU interpreting the CSG
broadcast; and the WTRU ignoring the indication that the cell is
restricted and trying to connect to the Node B based on the
interpretation of the CSG broadcast that indicates that the cell is
reserved for the CSG.
74. The method of claim 73, further comprising the WTRU receiving a
closed subscriber group identity (CSG ID), wherein the CSG ID is
included in a system information block (SIB) broadcast by the Node
B.
75. The method of claim 73, wherein the CSG broadcast comprises a
status bit indicating whether the cell is available or
unavailable.
76. The method of claim 73, wherein the WTRU supports HNB services,
and wherein the other WTRUs fail to support HNB services.
77. The method of claim 76, wherein the other WTRUs comprise legacy
WTRUs.
78. The method of claim 77, wherein the indication that the cell is
restricted indicates that the legacy WTRUs are barred from
accessing the cell.
79. The method of claim 77, wherein the WTRU is a release 8 (R8)
WTRU.
80. The method of claim 73, wherein the indication that the cell is
restricted comprises an access restriction indicating that the cell
is barred, reserved for future extension, or reserved for operator
use.
81. A wireless transmit/receive unit (WTRU) comprising: a
transceiver configured to transmit and receive signals; and a
controller configured to: receive, via the transceiver, an
indication from a Node B that a cell is restricted, and wherein the
indication is capable of being interpreted by the WTRU and other
WTRUs, receive, via the transceiver, a closed subscriber group
(CSG) broadcast that indicates that the cell is reserved for a CSG,
wherein the CSG broadcast is configured to be interpreted by the
WTRU, and wherein the CSG broadcast is configured to be unable to
be interpreted by the other WTRUs, interpret the CSG broadcast, and
ignore the indication that the cell is restricted and try to
connect to the Node B based on the interpretation of the CSG
broadcast that indicates that the cell is reserved for the CSG.
82. The WTRU of claim 81, wherein the controller is configured to
receive, via the transceiver, a closed subscriber group identity
(CSG ID), wherein the CSG ID is received in a system information
block (SIB) broadcast by the Node B.
83. The WTRU of claim 81, wherein the other WTRUs comprise legacy
WTRUs.
84. The WTRU of claim 83, wherein the indication that the cell is
restricted indicates that the legacy WTRUs are barred from
accessing the cell and that the legacy WTRUs are not allowed to use
a frequency of the cell for future cell reselections.
85. The WTRU of claim 83, wherein the WTRU is a release 8 (R8)
WTRU.
86. The WTRU of claim 81, wherein the CSG broadcast comprises a
status bit indicating whether the cell is available or
unavailable.
87. The WTRU of claim 81, wherein the WTRU supports HNB services,
and wherein the other WTRUs fail to support HNB services.
88. The WTRU of claim 81, wherein the indication that the cell is
restricted comprises an access restriction indicating that the cell
is barred, reserved for future extension, or reserved for operator
use.
89. A method comprising: transmitting an indication from a Node B
to one or more wireless transmit/receive units (WTRUs) that a cell
is restricted; transmitting a closed subscriber group (CSG)
broadcast from the Node B, wherein the CSG broadcast is configured
to be interpreted by at least one WTRU, and wherein the CSG
broadcast is configured as being unable to be interpreted by other
WTRUs; receiving a connection request at the Node B from the at
least one WTRU, which ignored the indication that the cell is
restricted based on the CSG broadcast; and allowing the at least
one WTRU to camp on the cell in response to the connection
request.
90. The method of claim 89, further comprising the Node B
transmitting a closed subscriber group identity (CSG ID), wherein
the CSG ID is transmitted in a system information block (SIB)
broadcast by the Node B.
91. The method of claim 89, wherein the CSG broadcast comprises a
status bit indicating whether the cell is available.
92. The method of claim 89, wherein the other WTRUs do not support
home Node B (HNB) features.
93. The method of claim 89, wherein the other WTRUs comprise legacy
WTRUs.
94. The method of claim 93, wherein the indication indicates that
the legacy WTRUs are barred from accessing the cell.
95. The method of claim 93, wherein the at least one WTRU is a
release 8 (R8) WTRU.
96. The method of claim 89, wherein the CSG broadcast comprises an
indication that WTRUs that support CSG features are allowed access
to the cell.
97. A Node B comprising: a transceiver configured to transmit and
receive signals; and a controller configured to: transmit, via the
transceiver, an indication to one or more wireless transmit/receive
units (WTRUs) that a cell is restricted, transmit, via the
transceiver, a closed subscriber group (CSG) broadcast, wherein the
CSG broadcast is configured to be interpreted by at least one WTRU,
and wherein the CSG broadcast is configured as being unable to be
interpreted by other WTRUs, receive a connection request from the
at least one WTRU, which ignored the indication that the cell is
restricted based on the CSG broadcast, and allow the at least one
WTRU to camp on the cell in response to the connection request.
98. The Node B of claim 97, wherein the controller is further
configured to transmit, via the transceiver, a closed subscriber
group identity (CSG ID), wherein the controller is configured to
broadcast the CSG ID in a system information block (SIB).
99. The Node B of claim 97, wherein the CSG broadcast comprises a
status bit indicating whether the cell is available.
100. The Node B of claim 97, wherein the other WTRUs do not support
home Node B (HNB) features.
101. The Node B of claim 97, wherein the other WTRUs comprise
legacy WTRUs.
102. The Node B of claim 101, wherein the indication indicates that
the legacy WTRUs are barred from accessing the cell.
103. The Node B of claim 101, wherein the at least one WTRU is a
release 8 (R8) WTRU.
104. The Node B of claim 97, wherein the CSG broadcast comprises an
indication that WTRUs that support CSG features are allowed access
to the cell.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. provisional
application Nos. 60/975,835 filed Sep. 28, 2007 and 61/048,104
filed Apr. 25, 2008, which are incorporated by reference as if
fully set forth.
FIELD OF INVENTION
[0002] This application is related to wireless communications.
BACKGROUND
[0003] With the evolution of the third generation (3G) network and
the increase of the number of wireless transmit/receive units
(WTRUs) being used, operators are pursuing solutions for new
services with higher data rates at reduced costs. An introduction
of home Node B (HNB) is considered as a viable candidate solution
and is currently being studied as part of third generation
partnership project (3GPP) Release 8. The HNB offers services over
relatively small service areas, such as home or office. It has a
similar role to a wireless local area network (WLAN) access point
(AP). The service may be provided where cellular coverage is poor
or non-existent. A subscriber typically will own the HNB and have
control over its final deployment location. The backhaul link from
the HNB to the network may be achieved through the conventional
access technologies, (e.g., digital subscriber line (DSL), cable
modem, wireless, etc.). A set of HNBs are connected to a HNB
gateway (GW) that provides an interface to the core network.
[0004] A subscriber is able to configure the HNB as its "desired"
or "preferred" HNB by using the concept of a closed subscriber
group (CSG). A CSG identifies WTRUs that are permitted to access
the HNB. An HNB cell may be configured to only allow access from a
set of WTRUs that are part of the CSG. This has implications for
initial access registration during WTRU power up, or roaming while
in an idle mode. Although legacy (pre-Release 8) mobility
management signaling can be used to address the access control
problem, it is not efficient. Once a WTRU camps on a cell or
reselects a cell, the WTRU sends a location area (LA) update
message to a network mobility management entity every time the WTRU
changes an LA. The LA is broadcast in the non-access stratum (NAS)
specific information within the system information block 1. (SIB1)
message. If the WTRU is not part of the CSG for the HNB cell, the
network will respond with a location area reject message. The WTRU
may then add this LA to its "forbidden LA" list.
[0005] An idle mode WTRU may make multiple registration attempts
(in vain) as the WTRU roams through an area with a high
concentration of HNBs that do not have the WTRU in their CSG. This
results in an increased signaling load and should be avoided.
[0006] With respect to cell reselection, a WTRU in the vicinity of
its "preferred" HNB should reselect the preferred HNB cell. This
implies that some mechanism must be in place to encourage this cell
reselection. For 3GPP Release 7 and earlier, cell reselection
measurements on neighbour cells are only triggered when the quality
level of the current cell (S) is not met for N.sub.serv DRX cycles,
or is less than S.sub.intrasearch, S.sub.intersearch, or
S.sub.searchRATm. These parameters are broadcast as part of the
system information. This poses a problem if the WTRU should always
select its preferred HNB cell if it is in its vicinity. In
particular, additional mechanisms are required to trigger the
measurements and once triggered, the HNB cells should be favoured.
In addition, as the penetration of HNBs could be quite high, a
method is needed to restrict the amount of measurements that WTRUs
make in cells that are inaccessible.
[0007] All WTRUs may need to be allowed to camp on a CSG cell in
order to make an emergency call. With respect to localization, an
operator should be able to know the location of the HNBs in order
to provide emergency services.
[0008] Another issue with respect to the HNBs is that a WTRU in
URA_PCH state will send UTRAN routing area (URA) update messages
when the WTRU crosses a URA boundary. URAs typically encompass a
group of adjacent cells, and are defined to reduce the amount of
reselection signaling as WTRUs move across cells. The network knows
the location of the WTRUs at the URA level and pages a WTRU across
all cells belonging to the URA. In addition, each cell may belong
to more than one URA. The list of URAs is broadcast from the cell
as part of the system information. For HNB deployments, the HNBs
are not tied to a physical location and the user or owner of the
HNB has some flexibility in terms of placement of the HNBs.
Therefore, the scheme of a cell belonging to a static list of URAs
may not apply in the HNB scenario. In addition, the flexible HNB
deployment may also imply that idle mode paging procedures can be
improved.
SUMMARY
[0009] A method and apparatus for supporting HNB services are
disclosed. A WTRU receives HNB access restriction information from
an HNB and accesses the HNB if it is determined that an access to
the HNB is allowed based on the HNB access restriction information.
The HNB access restriction information may be a closed subscriber
group identity (CSG ID), a status bit indicating whether an HNB
cell is available or not, an identity of WTRUs that are allowed to
access the HNB, information indicating whether an access to a cell
is barred/reserved or not. The WTRU may perform measurements on
neighbor cells for cell reselection. In order to ensure that the
WTRU uses a suitable HNB cell when available, the measurement may
be triggered even though signal strength on a currently connected
cell is above a threshold for cell reselection. The measurement may
be triggered manually, periodically, under the instruction from the
network, or based on a neighbor cell list including information
about HNB cells located nearby. Parameters S.sub.intrasearch and
S.sub.intersearch may be set to lower values when the WTRU enters a
macro cell that includes an HNB cell for which the WTRU is part of
a CSG. The measurement may be triggered if it is determined that
the WTRU has entered a macro cell including an HNB based on the
detected location area (LA) or cell identity. An idle mode WTRU may
be paged across all cells in the LA. If this LA spans across more
than one HNB gateway (GW), the WTRU may be paged first on the last
accessed HNB GW and then paged in a remaining GWs that make up the
LA if the WTRU is not found through the last accessed HNB GW. The
URA list within an HNB cell may be changed dynamically to take into
account possible HNB relocation. Alternatively, the concept of URA
may be modified for HNB applications.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] A more detailed understanding may be had from the following
description, given by way of example in conjunction with the
accompanying drawings wherein:
[0011] FIG. 1 shows an example HNB deployment scenario;
[0012] FIG. 2 shows an example network architecture for HNB
deployment;
[0013] FIG. 3 is a block diagram of an example WTRU;
[0014] FIG. 4 is a block diagram of an apparatus, such as an HNB
GW, for supporting HNB services; and
[0015] FIG. 5 is a block diagram of an example Node B.
DETAILED DESCRIPTION
[0016] When referred to hereafter, the terminology "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
user device capable of operating in a wireless environment. When
referred to hereafter, the terminology "Node B" includes but is not
limited to a base station, 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
"HNB GW" includes any device used to interface between the HNBs and
the core network.
[0017] The terminology "supporting HNB features" refers to the
capability of a WTRU to read and use new HNB specific information
and to support and perform new HNB specific procedures. The
terminology "R8 WTRU" refers to a WTRU having a capability of
supporting HNB features, and the terminology "non-R8 WTRU" or
"legacy WTRU" refers to a WTRU that does not have such capability.
HNBs should support both R8 WTRUs and pre-R8 (legacy) WTRUs. R8
WTRUs will be able to take advantage of the new features, while the
legacy WTRUs will not be able to read or interpret any of the new
information elements (IEs) and will not be able to use any of the
new procedures. The terminology "low speed" refers to the WTRU
speed that allows a WTRU to access an HNB cell. The "low speed"
limit may be controlled by the network.
[0018] FIG. 1 shows an example HNB deployment scenario. HNBs 120a,
120b, 120c are deployed in three homes (not shown) and each HNB
120a, 120b, 120c is connected to a higher network node 140, (e.g.,
HNB GW). The HNBs 120a, 120b, and 120c cover a cell 122a, 122b, and
122c, respectively. HNBs 120a and 120b are covered by a 3G macro
cell 132 that is controlled by a macro Node B 130. HNB 120c is
deployed in an area where there is no 3G coverage, but covered by
another system. A WTRU 110 is currently close to the HNB 120a, but
may roam freely. For example, the WTRU 110 connected to HNB 120a
may move to HNB 120b, to the 3G macro cell 132, or to other system
cells.
[0019] FIG. 2 shows an example network architecture for HNB
deployment. The network 200 includes an HNB access network 142 and
a core network 150. The HNB access network 142 includes at least
one HNB 120 and at least one HNB gateway (GW) 140. HNBs 120 support
WTRUs 110 with a low speed, such as less than 30 km/hr. HNBs 120
are connected to the HNB GW 140, and the HNB GW 140 communicates
directly with the core network 150 through an Iu-like
interface.
[0020] Embodiments for access restriction are disclosed below.
[0021] In accordance with a first embodiment, a WTRU 110 and an HNB
120 are configured with a closed subscriber group identity
(CSG_ID). As stated above, only WTRUs that belong to the CSG for
the HNB are allowed to access the HNB 120. The CSG_ID identifies
the CSG for the HNB 120. The HNB 120 may be configured either
manually or through some operation and maintenance (OAM) procedure.
The WTRU 110 may be configured manually, through non-access stratum
(NAS) signaling, or through access stratum (AS) signaling. The HNB
120 may broadcast its CSG_ID as part of its system information and
only those WTRUs that have been configured with the same CSG_ID are
allowed to attempt registration with the HNB 120. Legacy WTRUs
would not be able to interpret the CSG_ID and would require an
alternate method to prevent an attempt to register with the network
through the HNB 120.
[0022] In accordance with a second embodiment, an HNB 120 may keep
track of all WTRUs within its CSG and if all of the WTRUs in the
CSG are either registered with or connected to the HNB 120, the HNB
120 may broadcast a status bit indicating to other WTRUs (those
that do not belong to the CSG) that the cell is not available. This
indication may be sent based on other criteria. For example, this
indication may be sent when it is determined that the cell is
unavailable based on high uplink or downlink load, too many WTRUs
registered, high backhaul load, or the like. Alternatively, the HNB
120 may use other mechanism to indicate its busy status (such as
barring the cell). This requires that the HNB 120 only bar the cell
to WTRUs that are not currently registered or connected.
[0023] In accordance with a third embodiment, an HNB 120 broadcasts
an identification of WTRUs that are allowed to access the HNB cell
in its system information. A WTRU 110 receives the identification
and cross-references its address with this information to determine
if the WTRU 110 is allowed for access. For example, WTRUs may be
grouped and may be identified through the group identity
(GROUP_ID). The grouping may be based on one of the WTRU identities
in an idle mode, (e.g., international mobile subscriber identity
(IMSI)). The HNB 120 broadcasts all GROUP_IDs that are part of its
CSG. A WTRU 110 attempts to register with the network via the HNB
120 if the WTRU 110 is part of one of these groups. This will
reduce the number of registration attempts, as only those WTRUs
that belong to the group will attempt for registration.
[0024] A flag in a bit mask may be used to indicate which group is
part of the CSG. The number of bits in the mask may correspond to
the number of groups. A K-bit mask would correspond to K groups,
and the group would be part of the CSG if the corresponding bit is
a `1`. For example, 16 bit mask 0000 1100 0000 0001 may imply that
groups 0, 10 and 11 are part of this CSG, where the least
significant bit is used as a flag for group 0 and the most
significant bit for group 15. As the number of WTRUs belonging to
each CSG increases, the bit mask size may be increased to
accommodate the larger number of GROUP IDs that would be
required.
[0025] In accordance with a fourth embodiment, in order to prevent
legacy WTRUs from trying to access the HNB 120, the HNB 120 may
broadcast the cell as being "barred", "reserved for further
extension", or "reserved for operator use". Upon detection of the
message indicating these restrictions, legacy WTRUs refrain from
accessing the HNB cell. If a cell is marked as "barred", the HNB
may use the "intra-frequency cell reselection indicator" to further
tailor cell selection/reselection. For instance, if the HNB 120 is
on a separate frequency from the macro Node B 130, the HNB 120 may
also broadcast the cell as being "not allowed" in an information
element "intra-frequency cell re-selection indicator" which bars
the entire frequency from future cell reselection attempts for the
legacy WTRUs.
[0026] Broadcasting the cell as being reserved for future extension
has an effect of barring the cell and not allowing the frequency to
be used in future cell reselections. As a result, it requires that
the HNB 120 and the macro Node B 130 be on separate frequencies.
Broadcasting the cell as being reserved for operator use has an
effect of barring the cell and not allowing the frequency to be
used in future cell reselections, (for all WTRUs of Class 0-9 and
12-14). As a result, it requires that the HNB 120 and the macro
Node B 130 be on separate frequencies.
[0027] An additional indication may be required to indicate that
the cell is an HNB cell, so that R8 WTRUs, (WTRUs supporting HNB
features), are allowed access to the HNB cell. For example, this
may be done by a new 2-bit IE, (Cell_Status bits), to indicate the
cell is an HNB cell as shown in Table 1.
TABLE-US-00001 TABLE 1 Cell_Status Interpretation 00 Non-Home Node
B cell 01 Home Node B cell (not barred) 10 Home Node B cell
(barred) 11 Reserved for future use
[0028] Alternatively, the R8 WTRUs may implicitly detect that this
cell is an HNB cell by means of other SIB information transmitted
from the cell, such a CSG broadcast from the cell or any other
HNB-only information. Once the cell is determined to be an HNB
cell, the R8 WTRUs ignore the barring of the cell and try to
connect or camp on it.
[0029] Embodiments for cell reselection to HNB are disclosed
below.
[0030] The conventional cell reselection procedure starts taking
measurements on other frequencies or other cells once the signal
strength of the currently connected cell, goes below a configured
threshold. However, with the introduction of HNBs the WTRU may
prefer to be connected to the HNB even if the signal strength of
the current cell, is above the configured threshold. The
conventional cell reselection triggering criteria is modified such
that the cell reselection measurement to an HNB cell, is triggered
even if the signal strength of the current cell is above the
threshold.
[0031] The cell reselection measurement to the HNB cell may be
triggered manually. A user may ask for a cell reselection when the
user is in vicinity of his/her preferred HNB.
[0032] The cell reselection measurement to the HNB cell may be
triggered periodically. A WTRU 110 that is part of the CSG may be
configured to periodically check for HNBs. Periodic searching may
be performed all the time, when the WTRU 110 is in the vicinity of
the HNB 120, or when the WTRU 110 is connected to a configured
public land mobile network (PLMN).
[0033] The cell reselection to the HNB cell may be facilitated by
setting the parameters S.sub.intrasearch and S.sub.intersearch
properly. A network, (e.g., radio network controller (RNC)), may
set S.sub.intrasearch and S.sub.interSearch parameters to a very
low values when a WTRU 110 enters a macro cell 132 that includes an
HNB cell for which the WTRU 110 is part of the CSG. This would
trigger the cell reselection measurements more frequently. This
would trigger more frequent cell reselection measurements for
legacy WTRUs as well. Therefore, as an alternative, new HNB
S.sub.intrasearch and HNB S.sub.intersearch parameters may be
broadcast only for the WTRUs that support HNB features.
[0034] Alternatively, the macro cell 132 may send a flag or a
dedicated message indicating to the WTRU 110 to start periodic cell
search.
[0035] The network may be aware of the location of HNBs 120a, 120b
(with respect to the macro cell 132) and the macro cell 132 may
include information about the HNB cells 122a, 122b in the neighbor
list broadcast by the macro cell 132 to the WTRUs 110, (for
example, as part of the intrafrequency/interfrequency cell info
list). Alternatively, the macro cell 132 may broadcast a list of
all CSG IDs that are supported by all the HNBs 120a, 120b covered
by that macro cell. When the WTRU 110 reads the CSG ID to which the
WTRU 110 belongs, the WTRU 110 triggers an HNB cell search.
[0036] Alternatively, the WTRU 110 may keep in memory the LA (or
tracking area (TA) or routing area (RA), hereinafter collectively
"LA") or CELL ID of the macro cell 132 in which the HNB 120 is
located. When the WTRU 110 detects that the WTRU 110 has entered a
macro cell 132 with the stored LA or CELL ID, the WTRU 110
automatically triggers a cell search for its HNB 120. If the HNB
120 is not detected the WTRU 110 may trigger a periodic search as
long as the WTRU 110 stays connected to the macro cell 132 with the
stored LA or CELL ID.
[0037] If the HNBs 120 use a separate frequency, the measurements
for cell reselection from the macro cell 132 to the HNB cell 122a,
122b may be performed during forward access channel (FACH)
measurement occasions, provided that the WTRU 110 prioritizes
searching on the HNB inter-frequencies.
[0038] Once the WTRU 110 has triggered measurements on neighbor
cells, the WTRU 110 should favor the HNB cells 122a, 122b during
evaluation of its cell reselection criteria. This may be achieved
by using the cell individual offsets which biases the measurements
in favor of the HNB cells 122a, 122b. Alternatively, the cell
reselection evaluation criteria may be modified to include
priorities. Alternatively, the HNBs 120a, 120b may be configured
with a different PLMN ID which may be given priority, (i.e.,
configured as preferred PLMN), over the macro cell's PLMN.
[0039] Release 8 WTRUs may tailor the cell reselection procedure
based on stored history of camping on HNB cells. The WTRU 110 may
either increase or reduce monitoring of HNB cells 122a, 122b and
macro-cells 132, depending on this history. For example, if the
WTRU 110 is camped or has recently been camped on an HNB cell 122a,
122b, the WTRU 110 may continue to monitor HNB cells 122a, 122b and
a macro cell 132. If on the other hand the WTRU 110 has not been
camped on an HNB cell 122a, 122b for some time, the WTRU 110 may
monitor the HNB cells 122a, 122b less frequently. The parameters
for determining the state may be configured through dedicated radio
resource control (RRC) signaling, through broadcast of system
information, or specified (hardcoded).
[0040] As there may be a requirement that HNBs 120 need to support
only WTRUs 110 with a low speed, (e.g., less than 30 km/hr),
Release 8 WTRUs may use mobility information to restrict cell
selection and reselection to HNB cells. The WTRU 110 may monitor
high mobility as in Release 7 by counting the number of cell
reselections in a time window. If this number exceeds a threshold,
the WTRU 110 declares itself a high mobility WTRU. The threshold
and window size are configured by the network and may be tailored
to declare high mobility when there is a high probability that the
WTRU 110 is not a low speed WTRU.
[0041] A new high mobility determination procedure may be defined
for WTRUs camped on HNBs, to better take into account the smaller
cell size of a HNB cell. In addition, it may base the count only on
cell reselection to HNB cells. For instance, a WTRU 110 may
determine high mobility based on the changes or variability in best
ranked cell (rather than cell reselections). The WTRU 110 may
monitor the best cell in successive intervals (the duration may be
based on the typical size of an HNB cell) and declare high mobility
if the best cell changes frequently.
[0042] While in CELL_DCH, a WTRU 110 reports measurement results to
the RNC through RRC signaling. As part of these measurements, a
WTRU 110 may report that an HNB cell has become part of its
detected set. If the WTRU 110 is permitted to access this HNB cell,
the RNC may signal (through RRC message) to the WTRU 110 to
continue monitoring this cell. If the WTRU 110 is not permitted to
access the cell, the WTRU 110 may be told to ignore the cell in
future measurements. In addition, if HNB cells are on a separate
frequency carrier, the RNC may further block future measurements on
this entire frequency if the WTRU 110 is not permitted to access
the HNB. The network may have different configuration parameters
(thresholds) for triggering the measurement report for a detected
HNB cell vs. a macro cell.
[0043] The network may determine the location of the HNB 120 using
one of the embodiments disclosed hereinafter. The HNB 120 may be
provided with the capability to measure transmissions from other
Node Bs. This information may be sent to the network for the HNB
location determination.
[0044] Alternatively, WTRUs 110 may be told to monitor or scan all
frequencies and send measurement information back to the network so
that the network may determine where the HNB 120 is located based
on the measurement information from the WTRUs 110. The measurement
may be triggered by the macro Node B 130 through a flag in its
broadcast information. Alternatively, a new RRC message may be sent
to request the measurements to the network. This may require a
compressed-mode like operation.
[0045] Alternatively, the WTRU 110 may simultaneously camp on two
cells (a macro cell 132 and an HNB cell 122a or 122b if one is
available). The WTRU 110 may time multiplex the transmissions to
both cells (in uplink and downlink) so that the WTRU 110 may
communicate with both cells. The network may then determine the
general location of the HNB 120 with respect to the macro cell 132.
The network may then direct the WTRU 110 to one of the Node Bs.
[0046] Embodiments for paging WTRUs are disclosed below.
[0047] WTRUs 110 that are camped on an HNB cell 122a, 122b (either
in IDLE, CELL_PCH, or URA_PCH states), need to be paged by the
network for any mobile terminated call. For IDLE mode, the network
knows the location of the WTRU 110 at the LA or RA level, and pages
the WTRU 110 in all cells belonging to the LA or RA. For CELL_PCH
WTRUs, the network knows the location of the WTRU 100 at the cell
level and WTRUs 110 are paged only in the particular cell. For
URA_PCH WTRUs, the network knows the location of the WTRU 110 at
the URA level and pages the WTRU 100 in all cells of the URA.
[0048] If the LA (or RA or TA) spans across more than one HNB GWs,
the HNB GW may append a GW identifier to each TA/LA/RA update
message. The network may then page a WTRU 110 in the last accessed
HNB GW first and then in the remaining GWs that make up the
TA/RA/LA.
[0049] If the TA/LA/RA spans a single HNB GW, the HNBs under the
single HNB GW may be subdivided into HNB paging areas (HPAs). The
HPA identity may be broadcast as part of the system information and
read during cell reselection. An HPA update may be triggered when
the WTRU 110 crosses an HPA boundary. The HPA update may terminate
at the HNB GW. The network may send the paging message to the HNB
GW, and the HNB GW forwards it to the last accessed HPA. This
embodiment may also be used if the TA/RA/LA spans across more than
one HNB GWs.
[0050] An HNB 120 may be provided with the capability to
dynamically change (or input to the network to allow it to change)
the URA list associated with an HNB cell as the HNB 120 is moved.
This may be achieved by using HNB localization information. One or
any combination of the following techniques can be used.
[0051] The network may assign URAs based on the overlay macro cell.
That is, the URA list may be made identical to the URA list of the
overlay macro cell. If the HNB 120 is moved to a new macro cell
coverage area, the network may update the URA list in the HNB 120
accordingly.
[0052] Alternatively, the HNB 120 may use some location device to
determine its position, (e.g., global positioning system (GPS)).
The HNB 120 provides the location information to the network. The
network cross-references the actual HNB location with the URA
boundaries and updates the URA list if the HNB 120 is moved.
[0053] Alternatively, the network may use reported WTRU
measurements to retrieve neighbor cell information and determine
the general location of the HNB. The network may use this
information to set up the HNB URA list.
[0054] Alternatively, the URA list may be tied to some other
criteria. For instance, in campus-type deployments the managing
entity may decide to segregate its HNBs according to physical
location, type, or capability of the HNB (considering parameters
such as capacity of HNB backhaul), or organizational structure
(e.g., each department in a warehouse can have its own URA). The
URA address space may be divided into K levels. For each level, a
set of URA addresses are available. This set may be referenced by a
group URA address. Each managing entity is assigned one or more
group URA addresses, and each of these group URA addresses is
associated with a set of URAs. The URA addresses within this first
level are assigned by the managing entity. The HNBs may be
configured with the URA list manually or through some OAM
procedure. When the network pages a WTRU, a gateway may determine
where to forward the paging message after it establishes the URA
from the WTRU ID.
[0055] Although presented as separate embodiments, it should be
noted that the embodiments disclosed above may be used alone or in
combination, with other embodiments. It should be further noted
that many of the techniques may be applied to other radio access
technologies (such as 3G long term evolution (LTE)).
[0056] FIG. 3 is a block diagram of an example WTRU 300. The WTRU
includes a transceiver 302 and a controller 304. The controller 304
is adapted to receive HNB access restriction information from an
HNB and access the HNB if it is determined that an access to the
HNB is allowed based on the HNB access restriction information, as
disclosed above.
[0057] The WTRU 300 may further include a measurement unit 306
adapted to perform measurement on neighbor cells or other
frequencies. The measurement for cell reselection is triggered and
performed even though signal strength on a currently connected cell
is above a threshold for cell reselection, as disclosed above. The
controller 304 performs a cell reselection to an HNB cell if cell
reselection criteria to the HNB cell are satisfied. The measurement
may be triggered manually, periodically, by setting parameters
S.sub.intrasearch and S.sub.interSearch to lower values when a WTRU
300 enters a macro cell that includes an HNB cell for which the
WTRU 300 is part of a CSG, in accordance with a message from a
network requesting a periodic cell search, based on a neighbor cell
list received from a macro cell including information about HNB
cells located nearby. The measurement may be triggered if it is
determined that the WTRU 300 has entered a macro cell including an
HNB based on the detected LA or cell identity of a macro cell. The
measurement may be performed depending on WTRU mobility.
[0058] FIG. 4 is a block diagram of an apparatus 400, (such as HNB
GW), for supporting HNB services. The apparatus 400 includes a
transceiver 402 and a controller 404. The controller 404 is
configured to perform the functions and procedures stated above.
For example, when a WTRU makes an LA update, the controller 404 may
append a GW identifier, allowing the network to send a paging
message for a WTRU to the last accessed HNB GW. The controller 404
may send the paging message to remaining GWs that make up the LA if
the WTRU is not found through the last accessed HNB GW. The
controller 404 may send the paging message to the last accessed HNB
Paging Area (HPA) if HNBs under an HNB gateway are subdivided into
HPAs. In accordance with another embodiment, the controller 404 may
update a URA list associated with an HNB cell as the HNB is
moved.
[0059] FIG. 5 is a block diagram of an example Node B 500. The Node
B 500 includes a transceiver 502 and a controller 504. The
controller 504 is adapted to perform the functions and procedures
for supporting the HNB services as stated above. For example, the
controller 504 is adapted to send HNB access restriction
information to WTRUs and accept a WTRU that is allowed to register
based on the HNB access restriction information.
[0060] 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).
[0061] 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.
[0062] 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) Ultra Wide Band (UWB)
module.
* * * * *