U.S. patent application number 14/295801 was filed with the patent office on 2015-01-15 for access point identification based on multiple pilot signature indicators.
This patent application is currently assigned to QUALCOMM Incorporated. The applicant listed for this patent is QUALCOMM Incorporated. Invention is credited to Chirag Sureshbhai Patel, Ravindra Manohar Patwardhan, Peter Hans Rauber, Peerapol Tinnakornsrisuphap, Mehmet Yavuz.
Application Number | 20150017991 14/295801 |
Document ID | / |
Family ID | 42939892 |
Filed Date | 2015-01-15 |
United States Patent
Application |
20150017991 |
Kind Code |
A1 |
Tinnakornsrisuphap; Peerapol ;
et al. |
January 15, 2015 |
ACCESS POINT IDENTIFICATION BASED ON MULTIPLE PILOT SIGNATURE
INDICATORS
Abstract
An access point is identified based on a plurality of pilot
signatures. Here, in addition to transmitting a pilot signal that
is encoded (e.g., spread/scrambled) using a particular pilot
signature, an access point transmits a message that includes at
least one indication of at least one other pilot signature. For
example, an access point may use one PN offset to generate a pilot
signal and transmit a message that identifies at least one other PN
offset. An access terminal that receives the pilot signal and the
message may then generate a pilot report that identifies all of
these pilot signatures. Upon receiving a handover message including
this pilot-related information, a target network entity with
knowledge of the pilot signatures assigned to that access point may
then accurately identify the access point as a target for handover
of the access terminal.
Inventors: |
Tinnakornsrisuphap; Peerapol;
(San Diego, CA) ; Patel; Chirag Sureshbhai; (San
Diego, CA) ; Yavuz; Mehmet; (San Diego, CA) ;
Rauber; Peter Hans; (Vienna, AT) ; Patwardhan;
Ravindra Manohar; (San Diego, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
QUALCOMM Incorporated |
San Diego |
CA |
US |
|
|
Assignee: |
QUALCOMM Incorporated
San Diego
CA
|
Family ID: |
42939892 |
Appl. No.: |
14/295801 |
Filed: |
June 4, 2014 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
12849947 |
Aug 4, 2010 |
|
|
|
14295801 |
|
|
|
|
61231635 |
Aug 5, 2009 |
|
|
|
Current U.S.
Class: |
455/437 |
Current CPC
Class: |
H04W 84/045 20130101;
H04W 36/0061 20130101; H04W 36/08 20130101 |
Class at
Publication: |
455/437 |
International
Class: |
H04W 36/00 20060101
H04W036/00; H04W 36/08 20060101 H04W036/08 |
Claims
1. (canceled)
2. A method of communication, comprising: allocating a plurality of
pilot signature indicators for an access point, wherein at least
one of the pilot signature indicators is indicative of at least one
pilot signature that is not currently allocated for pilot
scrambling use by any access points associated with an area of a
wireless network that includes at least one access point identified
by a pilot signature indicated by the pilot signature indicators;
and sending a message to the access point, wherein the message
includes the allocated pilot signature indicators.
3. The method of claim 3, wherein the pilot signature indicators
comprise pseudorandom noise (PN) offset values.
4. The method of claim 3, wherein the pilot signature indicators
comprise at least one pseudorandom noise (PN) phase value.
5. The method of claim 3, wherein the pilot signature indicators
comprise primary scrambling code values or physical cell identifier
values.
6. The method of claim 3, wherein the message further includes at
least one pilot signal strength indication associated with at least
one of the pilot signature indicators.
7. The method of claim 6, further comprising defining the at least
one pilot signal strength indication.
8. The method of claim 1, wherein one of the pilot signature
indicators is allocated for the access point to send a pilot
signal.
9. The method of claim 1, wherein the pilot signature indicators
are allocated to identify the access point for handover.
10. The method of claim 1, further comprising determining that more
than one pilot signature indicator is to be allocated for the
access point, wherein the determination is based on a type of the
access point.
11. The method of claim 10, wherein the type comprises a femto cell
type.
12. The method of claim 1, further comprising identifying a set of
unallocated pilot signatures from a set of available pilot
signatures, wherein: the set of unallocated pilot signatures
comprises pilot signatures that are not currently allocated for
pilot scrambling use by any access points associated with the area
of the wireless network; and the allocation of the plurality of
pilot signature indicators comprises selecting at least one pilot
signature from the set of unallocated pilot signatures.
13. The method of claim 1, wherein the access point comprises a
femto cell.
14. The method of claim 1, wherein the message is further sent to
at least one of the group consisting of: an access network, a femto
convergence server, and a femto gateway.
15. An apparatus for communication, comprising: a pilot processor
configured to allocate a plurality of pilot signature indicators
for an access point, wherein at least one of the pilot signature
indicators is indicative of at least one pilot signature that is
not currently allocated for pilot scrambling use by any access
points associated with an area of a wireless network that includes
at least one access point identified by a pilot signature indicated
by the pilot signature indicators; and a transmitter configured to
send a message to the access point, wherein the message includes
the allocated pilot signature indicators.
16. The apparatus of claim 15, wherein the message further includes
at least one pilot signal strength indication associated with at
least one of the pilot signature indicators.
17. The apparatus of claim 15, wherein: the pilot processor is
further configured to determine that more than one pilot signature
indicator is to be allocated for the access point; and the
determination is based on a type of the access point.
18. An apparatus for communication, comprising: means for
allocating a plurality of pilot signature indicators for an access
point, wherein at least one of the pilot signature indicators is
indicative of at least one pilot signature that is not currently
allocated for pilot scrambling use by any access points associated
with an area of a wireless network that includes at least one
access point identified by a pilot signature indicated by the pilot
signature indicators; and means for sending a message to the access
point, wherein the message includes the allocated pilot signature
indicators.
19. The apparatus of claim 18, wherein the message further includes
at least one pilot signal strength indication associated with at
least one of the pilot signature indicators.
20. The apparatus of claim 18, further comprising means for
determining that more than one pilot signature indicator is to be
allocated for the access point, wherein the determination is based
on a type of the access point.
21. A non-transitory computer-program product comprising code for
causing a computer to: allocate a plurality of pilot signature
indicators for an access point, wherein at least one of the pilot
signature indicators is indicative of at least one pilot signature
that is not currently allocated for pilot scrambling use by any
access points associated with an area of a wireless network that
includes at least one access point identified by a pilot signature
indicated by the pilot signature indicators; and send a message to
the access point, wherein the message includes the allocated pilot
signature indicators.
22. The non-transitory computer-program product of claim 21,
wherein the message further includes at least one pilot signal
strength indication associated with at least one of the pilot
signature indicators.
23. The non-transitory computer-program product of claim 21,
further comprising code for causing the computer to determine that
more than one pilot signature indicator is to be allocated for the
access point; and the determination is based on a type of the
access point.
Description
CLAIM OF PRIORITY
[0001] This application is a division of U.S. application Ser. No.
12/849,947, filed Aug. 4, 2010, which claims the benefit of and
priority to commonly owned U.S. Provisional Patent Application No.
61/231,635, filed Aug. 5, 2009, and assigned Attorney Docket No.
093165P1, which applications are hereby incorporated by reference
herein.
BACKGROUND
[0002] 1. Field
[0003] This application relates generally to communication and more
specifically, but not exclusively, to the use of multiple pilot
signature indicators for identifying an access point.
[0004] 2. Introduction
[0005] A wireless communication network may be deployed over a
geographical area to provide various types of services (e.g.,
voice, data, multimedia services, etc.) to users within that
geographical area. In a typical implementation, access points
(e.g., macro access points providing macro cell coverage) are
distributed throughout a network to provide wireless connectivity
for access terminals (e.g., cell phones) that are operating within
the geographical area served by the network.
[0006] As the demand for high-rate and multimedia data services
rapidly grows, there lies a challenge to implement efficient and
robust communication systems with enhanced performance. To
supplement conventional network access points (e.g., macro access
points), small-coverage access points may be deployed (e.g.,
installed in a user's home) to provide more robust indoor wireless
coverage or other coverage for access terminals. Such
small-coverage access points may be referred to as, for example,
femto access points, femto cells, home NodeBs, home eNodeBs, or
access point base stations. Typically, such small-coverage access
points are connected to the Internet and the mobile operator's
network via a DSL router or a cable modem.
[0007] As the access terminal roams throughout the geographical
area associated with the network, the access terminal may move away
from its serving access point and move closer to another access
point. Consequently, when an access terminal gets close to a
particular access point, it may be desired to handover (i.e., idle
or active handover) the access terminal to that particular access
point if that access point provides better radio frequency (RF)
coverage and/or additional services.
[0008] To enable such handover, access terminals in a network
regularly monitor for pilot signals from nearby access points to
identify potential target access points. To facilitate this
monitoring, each access point transmits a pilot signal with a
unique pseudo-random noise (PN) spreading code. Different access
points in the network may use a known pilot spreading code (also
sometimes known as scrambling code) with different phase
offsets--commonly referred to as PN offsets (e.g., for the case of
a cdma2000 network). Thus, an access point may be identified based
on the PN offset used by that access point. In conventional macro
networks, a target access point for handover of an access terminal
between two cells is identified based on a forward link (FL) pilot
report sent by the access terminal Such a report may be referred to
as, for example, a pilot strength measurement message (PSMM) or as
a Route Update (in CDMA high rate packet data technology). The
pilot report includes an indication of the FL signal quality
(typically pilot strength Ecp/Io) of neighboring access points and
pilot phase associated with each of these access points. The pilot
phase that is reported may then be mapped to the signature (e.g.
pilot PN offset) used by a particular access point. In this way,
the identity of the access point that transmitted given pilot
signal may be determined assuming no other access points are using
the signature.
[0009] For effective active (i.e., connected) handover of an access
terminal from one access point to another, the network needs to be
able to uniquely identify the target access point. However, the
number of available PN offsets is typically limited. In some cases,
the number of available PN offsets may be limited by the size of
the neighbor list that is used to assist access terminals in
searching for neighboring PN signals. Here, to reduce overhead and
improve efficiency, it may be desirable to limit the number of
entries in the neighbor list advertised by a macro access point to
a relatively small number (e.g., 20-40).
[0010] Consequently, in the event a relatively large number of
small-coverage access points are deployed in the same area (e.g.,
within the coverage of a single macro cell), several of these
access points may use the same PN offset for their pilot signals.
Unique identification for active handover to such an access point
may therefore be difficult due to PN offset confusion.
Specifically, confusion may exist as to which access point (e.g.,
which potential handover target) is being identified when an access
terminal in the network reports to its serving access point (e.g.,
the handover source) that a pilot signal having a given PN offset
has been received.
[0011] Conventional solutions for dealing with the above problem
include a mobile sensing scheme and a scheme where an access point
advertises a cell identifier. For example, in a mobile sensing
scheme, candidate target femto cells are requested to detect
signals from an access terminal on the reverse link (RL) and report
this information to the network. The network then identifies the
target based on which femto cell reported the best FL signal. In
practice, however, such a scheme may have scalability problems in
the event a large number of femto cells are deployed. In addition,
such a scheme may not provide a sufficient level of accuracy due to
FL/RL imbalances (e.g., the femto cell that reports the strongest
FL signal may not be the intended target).
[0012] In a cell identifier advertising scheme, a femto cell may
advertise an access point identification message that includes a
mobile switching center (MSC) related identifier (IOS_MSC_ID) and a
cell related identifier (IOS_CELL_ID) that uniquely identifies that
femto cell at the network. An access terminal may then report this
information to the network via a handoff supplementary information
notification message. However, such a scheme requires that the
macro access points be upgraded to support the handoff
supplementary information notification message. In addition such a
scheme does not support legacy access terminals. In view of the
above, there is a need for effective techniques for identifying
access points so that other nodes in the network may efficiently
communicate with the access points.
SUMMARY
[0013] A summary of sample aspects of the disclosure follows. In
the discussion herein, any reference to the term aspects may refer
to one or more aspects of the disclosure.
[0014] The disclosure relates in some aspects to using a plurality
of pilot signatures to provide a unique signature for identifying
an access point. For example, an access point may transmit a pilot
signal that is encoded (e.g., spread/scrambled) based on a
particular pilot signature, and also advertise at least one other
pilot signature (e.g., by transmitting a message that includes at
least one indication of at least one other pilot signature). As a
specific example, an access point may use one PN offset to generate
a pilot signal and transmit a message that identifies at least one
other PN offset. An access terminal that receives the pilot signal
and the message may then generate a pilot measurement report that
identifies all of these pilot signatures. Consequently, the pilot
measurement report may take the form of a legacy pilot measurement
report that may handled by a legacy network, while providing
pilot-related information (e.g., a defined set of PN offsets) that
more accurately identifies the access point. Upon receiving a
handover message including this pilot-related information, a target
network entity with knowledge of the pilot signatures assigned to
that access point may then accurately identify the access point as
a target for handover of the access terminal, as warranted.
[0015] The disclosure relates in some aspects to configuring an
access point and one or more network entities with the pilot
signature-related information that identifies an access point. For
example, a network entity may allocate a plurality of pilot
signature indicators (e.g., PN offsets) for an access point. The
network entity may then send a message including the allocated
pilot signature indicators to the access point. The network entity
also may send a message including the allocated pilot signature
indicators to one or more other network entities (e.g., entities
that may need to identify the access point based on the pilot
signature indicators).
[0016] The disclosure relates in some aspects to an access point
that advertises a plurality of pilot signatures. For example, upon
receiving an allocation of pilot signature indicators, the access
point may transmit a pilot signal based on one of these pilot
signature indicators. In addition, the access point may generate
and then transmit a message including the other allocated pilot
signature indicator(s).
[0017] The disclosure relates in some aspects to an access terminal
that generates a pilot report that includes indications of all of
the pilot signatures allocated for an access point. For example,
upon receiving the pilot signal and message transmitted by an
access point, the access terminal may generate and then transmit a
pilot report that includes at least one indication that is based on
the received pilot signature indicator(s) and one indication based
on the pilot signature associated with the received pilot
signal.
[0018] The disclosure relates in some aspects to a identifying an
access point as a handover target based on received information
that is indicative of all of the pilot signatures allocated for
that access point. For example, a network entity may determine
(e.g., obtain) a mapping that maps different access points to
different sets of cell identifiers or pilot signature indicators.
Thus, upon receiving a handover-related message for an access
terminal that includes a plurality of cell identifiers or pilot
signature indicators, the network entity may identify one of these
access points as the handover target based on the mapping and the
received cell identifiers or pilot signature indicators.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] These and other sample aspects of the disclosure will be
described in the detailed description and the appended claims that
follow, and in the accompanying drawings, wherein:
[0020] FIG. 1 is a simplified block diagram of several sample
aspects of a communication system adapted to identify an access
point based on a plurality of pilot signature indicators;
[0021] FIGS. 2 and 3 are a flowchart of several sample aspects of
operations that may be performed in conjunction with identifying an
access point based on a plurality of pilot signature
indicators;
[0022] FIG. 4 is a simplified block diagram of several sample
aspects of a communication system adapted to identify an access
point based on a plurality of cell identifiers associated with
pilot signature indicators allocated to the access point;
[0023] FIG. 5 is a simplified block diagram of several sample
aspects of a communication system adapted to identify an access
point based on a plurality of PN phases associated with pilot
signature indicators allocated to the access point;
[0024] FIG. 6 is a flowchart of several sample aspects of
operations that may be performed in conjunction with configuring
pilot signature indicators for an access point;
[0025] FIG. 7 is a flowchart of several sample aspects of
operations that may be performed in conjunction with advertising
pilot signature indicators at an access point;
[0026] FIG. 8 is a flowchart of several sample aspects of
operations that may be performed in conjunction with providing a
pilot report based on pilot signature indicators received from an
access point;
[0027] FIG. 9 is a flowchart of several sample aspects of
operations that may be performed in conjunction with identifying a
target access point based on pilot signature indicator-based
information;
[0028] FIG. 10 is a simplified block diagram of several sample
aspects of a CDMA 1.times. communication system adapted to identify
an access point based on a plurality of pilot signature
indicators;
[0029] FIG. 11 is a simplified block diagram of several sample
aspects of a CDMA HRPD communication system adapted to identify an
access point based on a plurality of pilot signature
indicators;
[0030] FIG. 12 is a simplified block diagram of several sample
aspects of components that may be employed in communication
nodes;
[0031] FIG. 13 is a simplified diagram of a wireless communication
system;
[0032] FIG. 14 is a simplified diagram of a wireless communication
system including femto nodes;
[0033] FIG. 15 is a simplified diagram illustrating coverage areas
for wireless communication;
[0034] FIG. 16 is a simplified block diagram of several sample
aspects of communication components; and
[0035] FIGS. 17-21 are simplified block diagrams of several sample
aspects of apparatuses configured to perform operations related to
identifying an access point based on a plurality of pilot signature
indicators as taught herein.
[0036] In accordance with common practice the various features
illustrated in the drawings may not be drawn to scale. Accordingly,
the dimensions of the various features may be arbitrarily expanded
or reduced for clarity. In addition, some of the drawings may be
simplified for clarity. Thus, the drawings may not depict all of
the components of a given apparatus (e.g., device) or method.
Finally, like reference numerals may be used to denote like
features throughout the specification and figures.
DETAILED DESCRIPTION
[0037] Various aspects of the disclosure are described below. It
should be apparent that the teachings herein may be embodied in a
wide variety of forms and that any specific structure, function, or
both being disclosed herein is merely representative. Based on the
teachings herein one skilled in the art should appreciate that an
aspect disclosed herein may be implemented independently of any
other aspects and that two or more of these aspects may be combined
in various ways. For example, an apparatus may be implemented or a
method may be practiced using any number of the aspects set forth
herein. In addition, such an apparatus may be implemented or such a
method may be practiced using other structure, functionality, or
structure and functionality in addition to or other than one or
more of the aspects set forth herein. Furthermore, an aspect may
comprise at least one element of a claim.
[0038] FIG. 1 illustrates several nodes of a sample communication
system 100 (e.g., a portion of a communication network). For
illustration purposes, various aspects of the disclosure will be
described in the context of one or more access terminals, access
points, and network entities that communicate with one another. It
should be appreciated, however, that the teachings herein may be
applicable to other types of apparatuses or other similar
apparatuses that are referenced using other terminology. For
example, in various implementations access points may be referred
to or implemented as base stations, access networks, or NodeBs, and
so on, while access terminals may be referred to or implemented as
user equipment, or mobile stations, and so on.
[0039] Access points in the system 100 provide one or more services
(e.g., network connectivity) for one or more wireless terminals
(e.g., access terminal 102) that may be installed within or that
may roam throughout a coverage area of the system 100. For example,
at various points in time the access terminal 102 may connect to an
access point 104, an access point 106, or some other access point
in the system 100 (not shown). Each of these access points may
communicate with one or more network entities (represented, for
convenience, by network entities 108) to facilitate wide area
network connectivity. A network entity may take various forms such
as, for example, one or more radio and/or core network entities.
Thus, in various implementations a network entity may represent
functionality such as at least one of: radio network control,
network management (e.g., via an operation, administration,
management, and provisioning entity), call control, session
management, mobility management, gateway functions, interworking
functions, or some other suitable network functionality.
[0040] In accordance with the teachings herein, a pilot signature
configuration entity 110 allocates a plurality of pilot signature
indicators for certain access points in the system 100. For
example, the pilot signature configuration entity 110 may allocate
two or more PN offsets for the access point 104 (e.g., a femto
cell). The pilot signature configuration entity 110 also may send
this information to other entities in the system 100. For example,
a target identification entity 112 may use this pilot signature
information to identify the access point as a target for a handover
procedure.
[0041] The access point 104 uses one of its allocated pilot
signature indicators for transmitting a pilot signal and advertises
the other allocated pilot signature indicator(s). That is, the
access point 104 may broadcast a message that identifies the other
allocated pilot signature indicator(s). This message also may
include a defined (e.g., artificial) indication of pilot strength
(e.g. Ecp/Io--the ratio of received pilot energy to the total
received power) associated with each pilot signature indicator
included in the message.
[0042] When the access terminal 102 is in the vicinity of the
access point 102, the access terminal 102 may receive the pilot
signal and the message transmitted by the access point 104. In
accordance with the teachings herein, the access terminal 102
generates a pilot report that includes pilot signature indicators
based on the received pilot signal and the received message. For
example, the pilot report may include an indication of the PN
offset that the access point 104 used to transmit the pilot signal
and the pilot report may include one or more indications of the PN
offsets that were identified in the message sent by the access
point 104. For each PN offset, this report may include pilot
measurement information such as, for example, the PN phase
corresponding to the PN offset, as well as a corresponding
indication of pilot strength. Also, in the event there are other
access points in the vicinity of the access terminal, the pilot
report may include similar pilot signature-related information for
these other access points.
[0043] In accordance with conventional practice, at some point in
time, the access terminal 102 sends the pilot report to its current
serving access point (e.g., access point 106). If the information
in the pilot report indicates that handover of the access terminal
is warranted, a handover message include information based on the
pilot report may be sent to another network entity (e.g., the
entity 112) that is able to determine the identity of the target
access point for handover of the access terminal 102. In accordance
with conventional practice, this handover message may include, for
example, the reported PN phases or cell identifiers corresponding
to the reported PN phases. The entity 112 may then use the pilot
signature configuration information it received from the entity 110
to identify any access points that use PN phases that match those
indicated by the pilot signature-related information received via
the handover message.
[0044] These and other aspects of the disclosure will now be
described in more detail in conjunction with the flowchart of FIGS.
2 and 3. For convenience, the operations of FIGS. 2 and 3 (or any
other operations discussed or taught herein) may be described as
being performed by specific components (e.g., components as shown
in FIGS. 1, 10, 11, and 12). It should be appreciated, however,
that these operations may be performed by other types of components
and may be performed using a different number of components. It
also should be appreciated that one or more of the operations
described herein may not be employed in a given implementation.
[0045] As represented by block 202 of FIG. 2, at some point in time
a network entity allocates pilot signature indicators for an access
point. For example, a femto management server may allocate two or
more PN offsets for a femto cell when that femto cell is deployed.
In such a case, the pilot signature indicators may identify the PN
offsets (e.g., a number from 0 to 511 for a case where 512 PN
offsets are available for use) or may identify the corresponding PN
phases (e.g., the number of chips corresponding to the phase shift
from PN phase 0). It should be appreciated that other types of
pilot signature indicators may be employed in different
implementations. For example, a pilot signature indicator may
identify a primary scrambling code (PSC) or a physical cell
identifier (PCI) that is used for spreading (scrambling) a pilot
signal.
[0046] The network entity allocates one of the pilot signature
indicators for transmitting a pilot signal and the remaining pilot
signature indicator(s) is/are used for identification of the access
point. For example, in a case where three pilot signature
indicators are allocated for an access point, the access point
generates a pilot signal based on one of the pilot signature
indicators and advertises the other two pilot signature indicators.
As discussed in more detail below, a pilot signature indicator
allocated for non-pilot signal use may be obtained from a set of
pilot signature indicators that are not allocated for pilot signal
use in a corresponding area of the network (e.g., the coverage area
managed by a particular mobile switching center).
[0047] In some cases, the network entity also defines a pilot
signal strength indication to be advertised along with each
advertised pilot signature indicator. As discussed in more detail
below, this defined pilot signal strength indication may
subsequently be used by an access terminal to generate a pilot
report.
[0048] As represented by block 204, the network entity configures
the access point by sending a message including the allocated pilot
signature indicators to the access point. If applicable, this
message also includes one or more pilot signal strength
indications. As discussed herein, the network entity may also send
this configuration information to one or more other entities in the
network.
[0049] The access point receives the pilot signature indicators as
represented by block 206. Then, based on one of the received pilot
signature indicators, the access point transmits a pilot signal as
represented by block 208. For example, the access point may
transmit its pilot signal through the use of a spreading code
(e.g., a PN spreading code) that is based on the allocated pilot
indicator (e.g., a particular PN offset).
[0050] As represented by block 210, the access point also generates
and transmits a message (e.g., an access point identifier message
(APIDM)) that includes at least one of the received pilot signature
indicators other than the received pilot signal that is used to
transmit the pilot signal. For example, the access point may
receive indications of PN offsets 0 and 2 at block 206. The access
point may then use PN offset 0 for sending the pilot signal at
block 208. In this case, the message generated at block 210 will
include an indication that is based on PN offset 2. In some
implementations, the message also may optionally include an
indication that is based on PN offset 0 in this example.
[0051] The message generated at block 210 may include a pilot
signal strength indication for each advertised pilot signature
indicator. As mentioned above, in some cases the access point is
configured with the pilot signal strength indication(s). In other
cases, however, the access point may define the pilot signal
strength indication(s).
[0052] As represented by blocks 212 and 214, an access terminal in
the vicinity of the access point may receive the pilot signal and
the message transmitted by the access point (as well as similar
information transmitted by any other nearby access points).
Accordingly, the access terminal may acquire the pilot
signature-related information transmitted by the access point. For
example, by decoding the received pilot signal, the access terminal
may identify the PN offset used to transmit the pilot signal. In
addition, the access terminal may read the PN offsets included in
the received message.
[0053] The information received at blocks 212 and 214 may trigger
the sending of a pilot report. For example, sending of a report may
be triggered if a received signal strength of a pilot signal
exceeds a certain threshold level (e.g., exceeds the received
signal strength of a signal from the serving macro cell by a
defined margin).
[0054] As represented by block 216 of FIG. 3, the access terminal
generates and transmits a pilot report that includes at least one
indication based on the pilot signature indicator(s) received via
the message. Such an indication may take various forms depending on
the form of the received pilot signature indicator and whether the
access terminal converts the received indicator to another form.
For example, in some cases the access terminal receives PN offsets
from the access point and converts these PN offsets to the
corresponding PN phases, and includes indications of these PN
phases in the pilot report. In other cases, the access terminal
receives PN phases from the access point and includes indications
of these PN phases in the pilot report.
[0055] The pilot report also includes a pilot signal strength
indication for each indication entry in the report. For example,
the access terminal may measure the signal strength of the pilot
signal received at block 212 and include an indication of this
value in the pilot report. In addition, the access terminal may
include the pilot signal strength indications received via the
message at block 214 in the pilot report.
[0056] Advantageously, this pilot report may be provided in a form
that is compatible with the operation of legacy network entities.
For example, for hard handover for legacy mobile stations (and also
in CDMA HRPD), only pilot measurements (e.g., PN phases and
strengths) are reported. As discussed herein, the pilot report
transmitted at block 216 may simply include PN phase and received
signal strength information. Thus, the pilot report may be handled
by legacy entities even though the pilot report includes additional
information (e.g., additional PN phase indications) that is
ultimately used in combination by another network entity to
uniquely identify the access point.
[0057] As represented by block 218, a network entity (e.g., a macro
access point) currently serving the access terminal receives the
pilot report. In accordance with conventional practice, this
network entity or an associated network entity (e.g., a mobile
switching center) may determine whether handover of the access
terminal is warranted. For example, handover operations may be
triggered if one of the received signal strength values in the
pilot report exceeds a similar macro signal level by a defined
margin.
[0058] In some implementations (e.g., CDMA 1.times. technology),
the source network entity converts the received pilot signature
indicators to another form of indication. For example, a macro base
station (or an associated mobile switching center) may convert each
received PN phase to a corresponding cell identifier based on a
mapping known to that network entity. In such a case, the source
operations describe here may be performed on the basis of the
corresponding cell identifiers.
[0059] The source network entity (e.g., a mobile switching center)
also may determine whether it can identify the handover target. For
example, if the highest received signal strength is associated with
a PN phase (or a cell identifier as discussed above) that the
network entity knows is being used by a particular access point,
the network entity may communicate with that access point to
facilitate handover of the access terminal. On the other hand, if
the network entity does not know the identity of the access point
associated with that PN phase (or cell identifier), the network
entity may identify another network entity (e.g., through the use
of a look-up table) that advertises that it does know the identity
of the access point. For example, configuration information in a
source macro mobile switching center may indicate that another
mobile switching center can handle a particular cell identifier,
and that yet another mobile switching center can handle another
cell identifier. In such a case, the source network entity may send
a handover message including the received or generated
handover-related information to the other network entity as
represented by block 220.
[0060] From the above it may be seen that a legacy macro access
point may need to be configured with the PN phase indicators that
are allocated for being advertized (e.g., via an APIDM). However, a
mechanism for configuring an access point in this manner is already
available in legacy systems Implementation of the teachings herein
may thus only involve configuring the legacy macro access points
with the PN phase (and, in some cases, associated cell identifier)
information using this mechanism. Advantageously, the legacy entity
does not need to know about the actual combinations allocated for
an access point. Instead, this information is provided to another
entity (e.g., a femto convergence server or a femto gateway) that
performs the actual operation of identifying the access point.
[0061] As represented by block 222, a target network entity (e.g.,
a femto convergence server or a femto gateway) may receive the
handover message sent by the source network entity at block 220.
Thus, this message may include, for example, the pilot signature
indicators (e.g., PN phase indicators) or the cell identifiers
discussed above. In addition, the handover message may include the
received pilot signal strength indications described above.
[0062] As represented by block 224, at some point in time, the
target network entity determines a pilot-related information
mapping for a set of access points (e.g., the access points under
the supervision of the network entity). This mapping may take
different forms in different implementations. For example, in some
cases, a given entry of the mapping maps a given access point with
the set of the pilot signature indicators (e.g., PN phase
indicators or PN offset indicators) allocated for that access
point. In some cases, a mapping entry maps a given access point
with a set of cell identifiers that are, in turn, assigned to the
set of the pilot signature indicators that are allocated for the
access point.
[0063] As represented by block 226, the target network entity may
therefore identify the target access point for handover of the
access terminal based on the mapping and the received pilot
signature-related information. For example, the network entity may
compare the received PN phases indicators (or cell identifiers)
with the entries in the mapping to identify the access point that
transmitted the pilot signal and the message that caused these PN
phases indicators (or cell identifiers) to be sent to the target
network entity. As a specific example, if the highest received
signal strength in the measurement report is associated with PN
phases 0 and 2, the network entity determines which entry in the
mapping contains this set of PN phases. The network entity may then
look up the identity of the corresponding access point from this
entry.
[0064] As represented by block 228, once the appropriate target has
been identified, handover of the access terminal to the target is
performed. For example, the target network entity may facilitate
communication between the source access point and the target access
point to complete the handover.
[0065] FIG. 4 illustrates a simplified example of a CDMA 1.times.
system 400 that describes sample message flow that may be used in
such a system in accordance with the teachings herein. Here, a
femto management system (FMS) maintains a pool of PN offsets
(PN1-PN15) that may be allocated to femto cells. In this example,
PN2-PN4 are allocated for a particular femto cell as represented by
the arrow 402. The FMS also provisions this information to an
appropriate network entity (e.g., a femto convergence server (FCS)
or femto MSC) as represented by the arrow 404. The femto cell
broadcasts a message (e.g., APIDM) that includes PN2-PN4 and this
message is received by a mobile station (MS) in the vicinity. The
MS then transmits a pilot strength measurement message (PSMM) that
includes the corresponding PN phase information (PN phase2-PN
phase4) to its serving macro base station (BS). The macro BS, in
turn, sends corresponding cell identifiers (cell ID2-cell ID4) to
its macro MSC (via an Alp interface) which forwards the cell
identifiers to the target FCS/MSC (via an IS-41 interface). Here,
there is a 1:1 mapping between each PN offset (and PN phase) and
each cell ID. The target FCS/MSC then determines the handover
target based on the reported cell IDs.
[0066] FIG. 5 illustrates a simplified example of a CDMA HRPD
system 500 that describes sample message flow that may be used in
such a system in accordance with the teachings herein. Again, a
femto management system (FMS) maintains a pool of PN offsets
(PN1-PN15) that may be allocated to femto cells. PN2-PN4 are
allocated for a particular femto cell as represented by the arrow
502. The FMS also provisions this information to an appropriate
network entity (e.g., a femto gateway (FGW)) as represented by the
arrow 504. The femto cell then broadcasts a message (e.g., APIDM)
that includes PN2-PN4 that may be received by an access terminal
(AT) in the vicinity. The AT transmits a Route Update message that
includes the corresponding PN phase information (PN phase2-PN
phase4) to its serving macro access network (AN). The macro AN, in
turn, sends the PN phase information to the target FGW (by
embedding the Route Update message in an A16 session transfer
request). The target FGW then determines the handover target based
on the reported PN phases.
[0067] With the above in mind, additional details of operations
that may be performed in accordance with the teachings herein will
be described with reference to FIGS. 6-9.
[0068] FIG. 6 describes sample operations that may be performed to
allocate pilot signature indications for an access point. These
operations may be performed, for example, by a network entity such
as a femto management system.
[0069] As represented by block 602, a set of unallocated pilot
signatures that may be allocated to access points (e.g., femto
cells) are identified. For example, this set may comprise all of
the PN offsets that not being used by macro access points in a
given area.
[0070] In some cases, this set of pilot signatures may be
designated for non-pilot transmission use only. For example, out of
a set of available pilot signatures (e.g., 256 available PN
offsets), a first group may be designated for use for transmitting
pilot signals, while a second group may be designated only for
being sent in a message (e.g., APIDM) by an access point. In other
words, pilot signatures of the second group may not be used for
scrambling transmitted pilot signals. Advantageously, this second
group of pilot signatures may be used to identify access points
without the need to advertise these pilot signatures in a macro
neighbor list, and without the need for access terminals to conduct
searches for these pilot signatures. In some cases, a pilot
signature that is designated for transmitting pilot signals also
may be designated for being advertised (e.g., in an APIDM).
[0071] The allocation of a set of pilot signatures may be made for
a designated area. For example, the designation of a set of pilot
signatures so that they will only be advertised in APIDMs may only
apply to an area corresponding to the coverage areas of access
points supervised or controlled by a given femto management system
or a given mobile switching center. Thus, in some aspects, a pilot
signature indicator may comprise a value that is indicative of a
pilot signature that is not currently allocated for pilot
scrambling use by any access points associated with an area of a
wireless network.
[0072] As represented by block 604, at some point in time, pilot
signature allocation for an access point is commenced. For example,
a femto management system may initiate this allocation when a femto
cell is deployed, powered-up, reset, or reconfigured.
[0073] As discussed herein, this process may involve allocating
multiple pilot signature indicators for a single access point to
provide a unique signature for that access point that may then be
used to uniquely identify the access point during handover.
Accordingly, as represented by block 606, a determination may thus
be made that more than one pilot signature indication is to be
allocated for a given access point (e.g., for access point of a
given type). For example, all femto cells in a given network may be
allocated more than one PN offset while all other access points in
that network may be allocated a single PN offset.
[0074] Thus, as represented by block 608, the allocation entity may
allocate a plurality of pilot signature indicators (e.g., each of
which comprises a specific value corresponding to a particular PN
offset or PN phase) for a given access point. As discussed above,
one of these pilot signature indicators is allocated for
transmission of a pilot signal by the access point, while the
remaining pilot signature indicator(s) is/are allocated for being
advertised by the access point (e.g., via an APIDM).
[0075] As represented by block 610, the allocation entity may
optionally define pilot signal strength information for each pilot
signature indicator that is allocated for being advertised. In some
cases, this pilot signal strength is set to a value that ensures
there will not be undue interference with network handover trigger
mechanisms (e.g., the selected value won't trigger unnecessary
initiations of handover procedures). For example, the pilot signal
strength may be defined at a value that is below a minimum received
signal strength that is specified for maintaining a call with a
macro access point.
[0076] In some implementations, the defined pilot signal strength
may be used to define the identity signature for the access point.
That is, an identity signature for a given access point may be
generated by allocating different PN offset indictors (or PN phase
indicators) and different associated pilot strength values. Thus,
as discussed below, a network entity (e.g., femto convergence
server or femto gateway) also may take these pilot signal strength
indications into account when identifying the target for a
handover.
[0077] As represented by block 612, the allocation entity sends a
message that includes the allocated pilot signature indicators to
the access point. As discussed herein, this message may include PN
offset indicators, PN phase indicators, PSC indicators, PCI
indicators, or some other type of indicators. In addition, this
message may include the pilot signal strength indication(s) defined
at block 610.
[0078] As represented by block 614, the allocation entity also
sends a message that includes the allocated pilot signature
indicators (and, optionally, defined pilot signal strength
indication(s)) to one or more other network entities. For example,
this message may be sent to a femto convergence server, a femto
gateway (also referred to as a femto cell gateway), an access
network, some other entity, or some combination of these
entities.
[0079] FIG. 7 describes sample operations that may be performed by
an access point in conjunction with advertising its pilot
signature-related information. These operations commence at block
702 where the access point receives a configuration message that
includes the pilot signature indicators allocated for that access
point. In addition, as discussed above, in some cases this message
includes defined pilot signal strength information for one or more
of the pilot signature indicators.
[0080] As represented by block 704, the access point may optionally
define pilot signal strength information for each pilot signature
indicator that is allocated for being advertised (e.g., in the
event the access point did not receive any pilot signal strength
indications from the femto management system). In some cases, a
pilot signal strength indication is set to a value that ensures
there will not be undue interference with network handover trigger
mechanisms (e.g., as discussed above).
[0081] As represented by block 706, the access point transmits a
pilot signal based on one of the allocated pilot signature
indicators. For example, the access point may use an allocated PN
offset to adjust the phase of the spreading code the access point
uses to transmit the pilot signal.
[0082] As represented by block 708, the access point generates a
message that includes at least one of the received pilot signature
indicators other than the received pilot signal that is used to
transmit the pilot signal. This message also may include a pilot
signal strength indication for each advertised pilot signature
indicator as discussed herein.
[0083] As represented by block 710, the access point transmits the
message generated at block 708. For example, the access point may
repeatedly (e.g., periodically) broadcast an APIDM message or some
other suitable message (e.g., an existing message modified to
include the pilot information or a new message including this
information).
[0084] FIG. 8 describes sample operations that may be performed by
an access terminal in conjunction with generating a pilot report.
As discussed herein, this pilot report is based, in part, on
advertised pilot signature-related information received from an
access point.
[0085] As represented by block 802, the access terminal receives a
pilot signal from an access point. As represented by block 804, the
access terminal identifies the pilot signature (e.g., PN offset or
PN phase) that was used by the access point to send the pilot
signal (e.g., using known techniques).
[0086] As represented by block 806, the access terminal also
receives a message (e.g., APIDM) from the access point. As
discussed herein, this message includes at least one pilot
signature indicator allocated for that access point and,
optionally, defined pilot signal strength information for each
pilot signature indicator.
[0087] As represented by block 808, the access terminal optionally
determines pilot phase values (e.g., PN phases) associated with the
at least one pilot signature indicator received at block 806 and,
if necessary, the pilot signature determined at block 804. For
example, in the event a received pilot signature indicator
comprises a set of PN offsets, the access terminal may use the
following formula to calculate the PN phase (designated
PN_Phase.sub.i) for each PN offset (designated PN.sub.i):
PN_Phase.sub.i=(PILOT_ARRIVAL+(64.times.PN.sub.i)) mod 2.sup.15.
Here, PILOT_ARRIVAL is the measured arrival time of the physical
femto access point pilot (e.g., as defined in section 2.6.6.2.4 of
C.S0005-E).
[0088] As represented by block 810, the access terminal generates a
pilot report that includes at least one indication based on the
pilot signature indicator(s) received at block 806 and an
indication based on the pilot signature identified at block 804.
For example, these indications may correspond directly to the
received indicator(s) and identified pilot signature or these
indications may correspond to the pilot phase values (e.g., PN
phases) determined at block 808.
[0089] The pilot report also includes a pilot signal strength
indication for each indication entry in the report. For example,
the access terminal may measure the signal strength of the pilot
signal received at block 802 and include an indication of this
value in the pilot report. In some cases, the pilot signal strength
indication for each advertised pilot signature indicator also may
be set to this same value. Alternatively, the access terminal may
include any pilot signal strength information received at block 806
in the pilot report entry for each advertised pilot signature
indicator.
[0090] As represented by block 812, the access terminal transmits
the pilot report (e.g., a PSMM or Route Update) generated at block
810. For example, the access terminal may send the report to a
serving macro access point (e.g., a macro base station or access
network) for further processing.
[0091] FIG. 9 describes sample operations that may be performed in
conjunction with identifying a handover target based on access
point pilot signature information as taught herein. Two versions of
these operations are described. One version (e.g., corresponding to
the system 500 of FIG. 5) uses pilot signature indicators such as
PN phase indicators to identify a target and the other version
(e.g., corresponding to the system 400 of FIG. 4) uses cell
identifiers to identity a target. These operations may be
performed, for example, by a network entity such as a femto
convergence server, a femto gateway, or an access network.
[0092] As represented by block 902, at some point in time, a pilot
signature indicator mapping or a cell identifier mapping is
determined for a set of access points. Here, a pilot signature
indicator mapping maps different access points with different sets
of pilot signature indicators. For example, a given access point
may be mapped to the two PN phases (corresponding to two PN
offsets) that were allocated for that access point by the femto
convergence server. Similarly, a cell identifier mapping maps
different access points with different set of cells identifiers.
For example, a given access point may be mapped to two cell
identifiers (corresponding to two PN offsets) allocated for that
access point by the femto convergence server.
[0093] An entity may determine this mapping in various ways. In
some implementations, a network entity (e.g., a femto convergence
server or a femto gateway) generates the mapping (e.g., based on
configuration information received from the femto management
system). In some implementations the network entity receives the
mapping from another network entity (e.g., from the femto
management system).
[0094] As represented by block 904, at some point in time, the
network entity receives a message for handover of an access
terminal. As discussed herein, this message may include, for
example, pilot signature indicators (e.g., for system 500) or cell
identifiers (e.g., for system 400). In addition, this message may
include received pilot signal strength indications as discussed
herein.
[0095] As represented by block 906, the network entity may
determine whether more than one pilot signature indictor or cell
identifier is needed for identifying a target access point. For
example, in accordance with conventional practice, a PN phase or
cell identifier identified in the handover message (i.e., from the
pilot report) may be uniquely associated with a single access point
(e.g., a non-femto cell). In the event this PN phase or cell
identifier is associated with the strongest received pilot
strength, the target may be identified based solely on the
corresponding pilot signature indicator or cell identifier.
[0096] For other access points (e.g. femto cells), however, unique
identification of the access point is achieved only through the use
of multiple pilot signature indicators or cell identifiers. In
accordance with the teachings herein, the network entity may
determine whether multiple pilot signature indicators or cell
identifiers need to be used to identify a target based on analysis
of the pilot signature indicators received in the message. For
example, as discussed above, a dedicated set of PN offsets may be
allocated for being advertised only (i.e., not used for sending an
actual pilot signal). Thus, the value (e.g., PN phase 2-15) of a
pilot signature indicator or cell identifier (e.g., cell ID 2-15)
may indicate that it is associated with a specific type of access
point (e.g., femto cell) and that this pilot signature indicator or
cell identifier is to be used in conjunction with at least one
other pilot signature indicator or cell identifier to uniquely
identify an access point.
[0097] As represented by block 908, the target access point for
handover of the access terminal is identified based on the mapping
and the received pilot signature-related information. For example,
the network entity may compare the received PN phase indicators (or
cell identifiers) with the entries in the mapping to identify the
access point that transmitted the pilot signal and the message that
caused these PN phases indicators (or cell identifiers) to be sent
to the target network entity. As a specific example, if the highest
received signal strength in the measurement report is associated
with PN phases 0 and 2, the network entity determines which entry
in the mapping contains this set of PN phases. The network entity
may then look up the identity of the corresponding access point
from this entry.
[0098] Also, in some cases, the identification of the target access
point is based on the received pilot signal strength indications.
For example, in a situation where multiple access points are
identified by the received pilot signature-related information, the
access point associated with the highest pilot signal strength
indication (e.g., for the actual pilot signal) may be selected.
[0099] In addition, in some implementations, the pilot signal
strength indications are used to form the identity signature for an
access point. In this case, the mapping determined at block 902
will include the pilot signal strength information that was
designated for the access points. The network entity may thus
identify a target access point by comparing the pilot signal
strength indications received at block 904 with the pilot signal
strength indicator entries in the mapping. For example, two
different access points may be allocated the same PN offsets, but
different pilot signal strength indications. Thus, the
identification of an access point may be based on both the PN
offsets and the pilot signal strength indications.
[0100] As represented by block 910, once the appropriate target has
been identified, the network entity may facilitate handover of the
access terminal to the target (e.g., by informing the source access
point of the identity of the target access point).
[0101] For purposes of illustration, FIGS. 10 and 11 illustrate how
messaging as taught herein may be implemented in different types of
network architectures. FIG. 10 depicts a simplified example of a
CDMA 1.times. femto system 1000 (e.g., corresponding to the system
400 of FIG. 4). FIG. 11 depicts a simplified example of a CDMA HRPD
femto system 1100 (e.g., corresponding to the system 500 of FIG.
5).
[0102] Referring initially to FIG. 10, a femto access point (FAP)
communicates with a core network via a femto gateway (FGW). An
IPsec tunnel is established between the femto access point and the
femto gateway for carrying, for example, user traffic, Internet
Protocol (IP) traffic, and control traffic. For example, the media
gateway control function/media gateway (MGCF/MGW) facilitates the
transfer of user traffic from the core network to the femto access
point via an Fx1 interface. Similarly, an Fx2 interface is used to
transfer IMS traffic to and from the femto access point. A femto
management system (FMS) sends configuration and other information
to the femto access point via an Fm interface and to other network
entities such as a femto convergence server (connection not
shown).
[0103] An example of handover operations performed by the system
1000 in accordance with the teachings herein follows. A mobile
station (MS) receives an APIDM including at least one PN offset
from the femto access point (FAP) and sends a PSMM including the
corresponding PN phase information to a macro base station (BS).
The macro BS converts the pilot PN phase information to cell
identifiers and sends the resulting pilot signature information to
the MSC/MSCe via the A1/A1p interface. Here, a femto convergence
server (FCS) appears as a target mobile switching center (MSC) to
the macro 1.times. infrastructure system. Thus, the FCS identifies
the target 1.times. femto access point based on information the FCS
receives via an IS-41 FACDIR2 message from the MSC/MSCe.
[0104] Referring to FIG. 11, a femto access point (FAP)
communicates with the network via a security gateway (SeGW) and a
femto gateway (FGW). An IPsec tunnel is established between the
femto access point and the security gateway for carrying, for
example, user traffic, Internet Protocol (IP) traffic, and control
traffic. For example, traffic between the femto access point and a
macro HRPD access network/packet control function (AN/PCF) is
carried over the A13, A16 and A24 interfaces. Traffic between the
femto access point and an access network--authentication,
authorization and accounting entity (AN-AAA) is carried over an A12
interface. Traffic between the femto access point and a packet data
serving node (PDSN) is carried over the A10 and A11 interfaces. A
femto management system (FMS) sends configuration and other
information to the femto access point via an Fm interface and to
other network entities such as the femto gateway (connection not
shown).
[0105] An example of handover operations performed by the system
1100 in accordance with the teachings herein follows. An access
terminal (AT) receives an APIDM including at least one PN offset
from the femto access point (FAP) and sends a PSMM including the
corresponding PN phase information to a macro access network (AN)
entity. The macro access network sends the PN phase information to
the femto gateway via an embedded Route Update message sent over
the A16 interface. Here, the femto gateway performs an A16 proxy
function to allow the macro access network to handoff to the femto
system without requiring any changes to the macro access network.
The femto gateway identifies the target femto access point based on
the information in the Route Update message.
[0106] Various fields that may be provided in a message such an
APIDM to support pilot signature indicators as taught herein. Two
examples follow.
[0107] In a first example, a first field (e.g., 1 bit)
corresponding to a variable HO_PN_GROUP_INCL is set to a 1 when a
PN offset group is advertised in the message. Otherwise the first
field is set to a 0. A second field (e.g., 0 or 4 bits)
corresponding to a variable HO_PN_GROUP_COUNT contains the number
of PN offsets following this field. A third field (e.g., 0 or
(9.times.LOC_REC_LEN) bits) corresponding to a variable
PN_OFFSET_GROUP contains an array of 9-bit fields, each listing PN
offsets. Here, LOC_REC_LEN may correspond to maximum number of
available PN offsets. Also, the numbering (or offsetting) of these
PN offsets may need to be compatible with the PN_Inc (indicative of
the phase spacing being employed) of the macro base stations.
[0108] In a second example (see Table 3.7.2.3.2.39-5 in C.S0005-E
v2.0), an APIDM includes a first field (e.g., 3 bits) corresponding
to a variable HO_INFO_TYPE that is set to different values to
indicate the type of information that is included in a third field.
For example, a value of "001" in the first field indicates that the
third field includes a signature for a PSMM message. Conversely, a
value of "010" in the first field indicates that the third field
includes a signature for a Route Update message. A second field
(e.g., 8 bits) corresponding to a variable HO_INFO_LEN is set to
the length of the third field. The third field (e.g., HO_INFO_LEN
bits) includes information that depends on the value of the first
field as described above.
[0109] For a HO_INFO_TYPE of "001", the third field includes a
PSMM_SIG_COUNT field (e.g., 3 bits) and a PSMM_SIGNATURE field
(e.g., 21 bits). The PSMM_SIG_COUNT field is set to the number of
occurrences of the PSMM_SIGNATURE field. The PSMM_SIGNATURE field
is set to the signature of the base station to be included in PSMM
during handoff. The 15 MSBs are used in PILOT_PN_PHASE field and
the 6 LSBs are used in PILOT_STRENGTH field.
[0110] For a HO_INFO_TYPE of "010", the third field includes a
RUP_SIG_COUNT field (e.g., 3 bits) and a RUP_SIGNATURE field (e.g.,
21 bits). The RUP_SIG_COUNT field is set to the number of
occurrences of the RUP_SIGNATURE field. The RUP_SIGNATURE field is
set to the signature to be included in a Route Update message
during handoff from another HRPD access network to the HRPD access
network associated with the base station. The 15 MSBs are used in
PilotPNPhase field and the 6 LSBs are used in PilotStrength
field.
[0111] Various advantages may be achieved in a system implemented
in accordance with the teachings herein. Significantly, the macro
infrastructure need not be upgraded to support handover (e.g.,
active handover to femto cells) as taught herein. Rather, existing
database structures (e.g., PN phase and cell identifier lists) only
need to be configured to include the additional allocated PN
phases, cell identifiers, etc. Moreover, due to the large number of
unique signatures that may be created (e.g., by allocating 2, 3, 4,
or more PN offsets for an access point), accurate handover may
always be achieved for any currently practical system. Also, the
described techniques are scalable since, for example, the size of
the allocated PN offset groups may be expanded as needed. Also, the
described techniques involve relatively simple algorithms in the
femto convergence server and the femto gateway.
[0112] FIG. 12 illustrates several sample components that may be
incorporated into nodes such as an access terminal 1202, an access
point 1204 (e.g., a femto cell), a network entity 1206 (e.g., a FCS
or a FGW), and a network entity 1208 (e.g., a FMS) to perform
access point identification operations as taught herein. In
practice, the described components also may be incorporated into
other nodes in a communication system. For example, other nodes in
a system may include components similar to those described for the
network entity 1208 to provide similar allocation functionality.
Also, a given node may contain one or more of the described
components. For example, an access point may contain multiple
transceiver components that enable the access point to operate on
multiple frequencies and/or communicate via different
technologies.
[0113] As shown in FIG. 12, the access terminal 1202 and the access
point 1204 include transceivers 1210 and 1212, respectively, for
communicating with other nodes. The transceiver 1210 includes a
transmitter 1214 for sending signals (e.g., messages and reports)
and a receiver 1216 for receiving signals (e.g., pilot signals and
messages). Similarly, the transceiver 1212 includes a transmitter
1218 for sending signals (e.g., pilot signals and messages) and a
receiver 1220 for receiving signals (e.g., messages, indicators,
and indications).
[0114] The access point 1204, the network entity 1206, and the
network entity 1208 include network interfaces 1222, 1224, and
1226, respectively, for communicating with other nodes (e.g., other
network nodes). For example, the network interfaces 1222, 1224, and
1226 may be configured to communicate with one or more network
nodes via a wire-based or wireless backhaul. In some aspects, each
network interface may be implemented as a transceiver configured to
support wire-based or wireless communication. For example, the
network interface 1224 is depicted as including a transmitter
component 1228 (e.g., for sending messages) and a receiver
component 1230 (e.g., for receiving messages), while the network
interface 1226 is depicted as including a transmitter component
1232 (e.g., for sending messages) and a receiver component 1234
(e.g., for receiving messages).
[0115] The access terminal 1202, the access point 1204, the network
entity 1206, and the network entity 1208 also include other
components that may be used in conjunction with access point
identification operations as taught herein. For example, the access
terminal 1202 includes a pilot processor 1236 for performing pilot
signature-related operations (e.g., generating a pilot report,
determining pilot phase values, identifying pilot signatures) and
for providing other related functionality as taught herein. The
access point 1204 includes a pilot processor 1238 for performing
pilot signature-related operations (e.g., generating messages
including pilot signature-related indications, defining pilot
signal strength indications) and for providing other related
functionality as taught herein. The network entity 1208 includes a
pilot processor 1240 for performing pilot signature-related
operations (e.g., allocating pilot signature indicators, defining
pilot signal strength indications, determining that more than one
pilot signature indicator is to be allocated, identifying
unallocated pilot signatures) and for providing other related
functionality as taught herein. The network entity 1206 includes a
handover controller 1242 for performing handover-related operations
(e.g., determining a cell identifier mapping, determining a pilot
signature indicator mapping, identifying a handover target,
determining that a target is to be identified from a plurality of
cell identifiers) and for providing other related functionality as
taught herein.
[0116] In some implementations, the components of FIG. 12 may be
implemented in one or more processors (e.g., that uses and/or
incorporates data memory for storing information or code used by
the processor(s) to provide this functionality). For example, the
functionality of block 1236 (and optionally some of the
functionality of block 1210) may be implemented by a processor or
processors of an access terminal and data memory of the access
terminal (e.g., by execution of appropriate code and/or by
appropriate configuration of processor components). Similarly, the
functionality of block 1238 (and optionally some of the
functionality of block 1212 and/or block 1222) may be implemented
by a processor or processors of an access point and data memory of
the access point (e.g., by execution of appropriate code and/or by
appropriate configuration of processor components). The
functionality of block 1242 (and optionally some of the
functionality of block 1224) may be implemented by a processor or
processors of a network entity and data memory of the network
entity (e.g., by execution of appropriate code and/or by
appropriate configuration of processor components). The
functionality of block 1240 (and optionally some of the
functionality of block 1226) may be implemented by a processor or
processors of a network entity and data memory of the network
entity (e.g., by execution of appropriate code and/or by
appropriate configuration of processor components).
[0117] As discussed above, in some aspects the teachings herein may
be employed in a network that includes macro scale coverage (e.g.,
a large area cellular network such as a 3G network, typically
referred to as a macro cell network or a WAN) and smaller scale
coverage (e.g., a residence-based or building-based network
environment, typically referred to as a LAN). As an access terminal
(AT) moves through such a network, the access terminal may be
served in certain locations by access points that provide macro
coverage while the access terminal may be served at other locations
by access points that provide smaller scale coverage. In some
aspects, the smaller coverage nodes may be used to provide
incremental capacity growth, in-building coverage, and different
services (e.g., for a more robust user experience).
[0118] In the description herein, a node (e.g., an access point)
that provides coverage over a relatively large area may be referred
to as a macro access point while a node that provides coverage over
a relatively small area (e.g., a residence) may be referred to as a
femto access point. It should be appreciated that the teachings
herein may be applicable to nodes associated with other types of
coverage areas. For example, a pico access point may provide
coverage (e.g., coverage within a commercial building) over an area
that is smaller than a macro area and larger than a femto area. In
various applications, other terminology may be used to reference a
macro access point, a femto access point, or other access
point-type nodes. For example, a macro access point may be
configured or referred to as an access network, base station,
access point, eNodeB, macro cell, and so on. Also, a femto access
point may be configured or referred to as a Home NodeB, Home
eNodeB, access point base station, femto cell, and so on. In some
implementations, a node may be associated with (e.g., referred to
as or divided into) one or more cells or sectors. A cell or sector
associated with a macro access point, a femto access point, or a
pico access point may be referred to as a macro cell, a femto cell,
or a pico cell, respectively.
[0119] FIG. 13 illustrates a wireless communication system 1300,
configured to support a number of users, in which the teachings
herein may be implemented. The system 1300 provides communication
for multiple cells 1302, such as, for example, macro cells
1302A-1302G, with each cell being serviced by a corresponding
access point 1304 (e.g., access points 1304A-1304G). As shown in
FIG. 13, access terminals 1306 (e.g., access terminals 1306A-1306L)
may be dispersed at various locations throughout the system over
time. Each access terminal 1306 may communicate with one or more
access points 1304 on a forward link (FL) and/or a reverse link
(RL) at a given moment, depending upon whether the access terminal
1306 is active and whether it is in soft handoff, for example. The
wireless communication system 1300 may provide service over a large
geographic region. For example, macro cells 1302A-1302G may cover a
few blocks in a neighborhood or several miles in rural
environment.
[0120] FIG. 14 illustrates an exemplary communication system 1400
where one or more femto access points are deployed within a network
environment. Specifically, the system 1400 includes multiple femto
access points 1410 (e.g., femto access points 1410A and 1410B)
installed in a relatively small scale network environment (e.g., in
one or more user residences 1430). Each femto access point 1410 may
be coupled to a wide area network 1440 (e.g., the Internet) and a
mobile operator core network 1450 via a DSL router, a cable modem,
a wireless link, or other connectivity means (not shown). As will
be discussed below, each femto access point 1410 may be configured
to serve associated access terminals 1420 (e.g., access terminal
1420A) and, optionally, other (e.g., hybrid or alien) access
terminals 1420 (e.g., access terminal 1420B). In other words,
access to femto access points 1410 may be restricted whereby a
given access terminal 1420 may be served by a set of designated
(e.g., home) femto access point(s) 1410 but may not be served by
any non-designated femto access points 1410 (e.g., a neighbor's
femto access point 1410).
[0121] FIG. 15 illustrates an example of a coverage map 1500 where
several tracking areas 1502 (or routing areas or location areas)
are defined, each of which includes several macro coverage areas
1504. Here, areas of coverage associated with tracking areas 1502A,
1502B, and 1502C are delineated by the wide lines and the macro
coverage areas 1504 are represented by the larger hexagons. The
tracking areas 1502 also include femto coverage areas 1506. In this
example, each of the femto coverage areas 1506 (e.g., femto
coverage areas 1506B and 1506C) is depicted within one or more
macro coverage areas 1504 (e.g., macro coverage areas 1504A and
1504B). It should be appreciated, however, that some or all of a
femto coverage area 1506 may not lie within a macro coverage area
1504. In practice, a large number of femto coverage areas 1506
(e.g., femto coverage areas 1506A and 1506D) may be defined within
a given tracking area 1502 or macro coverage area 1504. Also, one
or more pico coverage areas (not shown) may be defined within a
given tracking area 1502 or macro coverage area 1504.
[0122] Referring again to FIG. 14, the owner of a femto access
point 1410 may subscribe to mobile service, such as, for example,
3G mobile service, offered through the mobile operator core network
1450. In addition, an access terminal 1420 may be capable of
operating both in macro environments and in smaller scale (e.g.,
residential) network environments. In other words, depending on the
current location of the access terminal 1420, the access terminal
1420 may be served by a macro cell access point 1460 associated
with the mobile operator core network 1450 or by any one of a set
of femto access points 1410 (e.g., the femto access points 1410A
and 1410B that reside within a corresponding user residence 1430).
For example, when a subscriber is outside his home, he is served by
a standard macro access point (e.g., access point 1460) and when
the subscriber is at home, he is served by a femto access point
(e.g., access point 1410A). Here, a femto access point 1410 may be
backward compatible with legacy access terminals 1420.
[0123] A femto access point 1410 may be deployed on a single
frequency or, in the alternative, on multiple frequencies.
Depending on the particular configuration, the single frequency or
one or more of the multiple frequencies may overlap with one or
more frequencies used by a macro access point (e.g., access point
1460).
[0124] In some aspects, an access terminal 1420 may be configured
to connect to a preferred femto access point (e.g., the home femto
access point of the access terminal 1420) whenever such
connectivity is possible. For example, whenever the access terminal
1420A is within the user's residence 1430, it may be desired that
the access terminal 1420A communicate only with the home femto
access point 1410A or 1410B.
[0125] In some aspects, if the access terminal 1420 operates within
the macro cellular network 1450 but is not residing on its most
preferred network (e.g., as defined in a preferred roaming list),
the access terminal 1420 may continue to search for the most
preferred network (e.g., the preferred femto access point 1410)
using a better system reselection (BSR) procedure, which may
involve a periodic scanning of available systems to determine
whether better systems are currently available and subsequently
acquire such preferred systems. The access terminal 1420 may limit
the search for specific band and channel. For example, one or more
femto channels may be defined whereby all femto access points (or
all restricted femto access points) in a region operate on the
femto channel(s). The search for the most preferred system may be
repeated periodically. Upon discovery of a preferred femto access
point 1410, the access terminal 1420 selects the femto access point
1410 and registers on it for use when within its coverage area.
[0126] Access to a femto access point may be restricted in some
aspects. For example, a given femto access point may only provide
certain services to certain access terminals. In deployments with
so-called restricted (or closed) access, a given access terminal
may only be served by the macro cell mobile network and a defined
set of femto access points (e.g., the femto access points 1410 that
reside within the corresponding user residence 1430). In some
implementations, an access point may be restricted to not provide,
for at least one node (e.g., access terminal), at least one of:
signaling, data access, registration, paging, or service.
[0127] In some aspects, a restricted femto access point (which may
also be referred to as a Closed Subscriber Group Home NodeB) is one
that provides service to a restricted provisioned set of access
terminals. This set may be temporarily or permanently extended as
necessary. In some aspects, a Closed Subscriber Group (CSG) may be
defined as the set of access points (e.g., femto access points)
that share a common access control list of access terminals.
[0128] Various relationships may thus exist between a given femto
access point and a given access terminal. For example, from the
perspective of an access terminal, an open femto access point may
refer to a femto access point with unrestricted access (e.g., the
femto access point allows access to any access terminal). A
restricted femto access point may refer to a femto access point
that is restricted in some manner (e.g., restricted for access
and/or registration). A home femto access point may refer to a
femto access point on which the access terminal is authorized to
access and operate on (e.g., permanent access is provided for a
defined set of one or more access terminals). A hybrid (or guest)
femto access point may refer to a femto access point on which
different access terminals are provided different levels of service
(e.g., some access terminals may be allowed partial and/or
temporary access while other access terminals may be allowed full
access). An alien femto access point may refer to a femto access
point on which the access terminal is not authorized to access or
operate on, except for perhaps emergency situations (e.g., 911
calls).
[0129] From a restricted femto access point perspective, a home
access terminal may refer to an access terminal that is authorized
to access the restricted femto access point installed in the
residence of that access terminal's owner (usually the home access
terminal has permanent access to that femto access point). A guest
access terminal may refer to an access terminal with temporary
access to the restricted femto access point (e g, limited based on
deadline, time of use, bytes, connection count, or some other
criterion or criteria). An alien access terminal may refer to an
access terminal that does not have permission to access the
restricted femto access point, except for perhaps emergency
situations, for example, such as 911 calls (e.g., an access
terminal that does not have the credentials or permission to
register with the restricted femto access point).
[0130] For convenience, the disclosure herein describes various
functionality in the context of a femto access point. It should be
appreciated, however, that a pico access point may provide the same
or similar functionality for a larger coverage area. For example, a
pico access point may be restricted, a home pico access point may
be defined for a given access terminal, and so on.
[0131] The teachings herein may be employed in a wireless
multiple-access communication system that simultaneously supports
communication for multiple wireless access terminals. Here, each
terminal may communicate with one or more access points via
transmissions on the forward and reverse links. The forward link
(or downlink) refers to the communication link from the access
points to the terminals, and the reverse link (or uplink) refers to
the communication link from the terminals to the access points.
This communication link may be established via a
single-in-single-out system, a multiple-in-multiple-out (MIMO)
system, or some other type of system.
[0132] A MIMO system employs multiple (N.sub.T) transmit antennas
and multiple (N.sub.R) receive antennas for data transmission. A
MIMO channel formed by the N.sub.T transmit and N.sub.R receive
antennas may be decomposed into N.sub.S independent channels, which
are also referred to as spatial channels, where
N.sub.S.ltoreq.min{N.sub.T, N.sub.R}. Each of the N.sub.S
independent channels corresponds to a dimension. The MIMO system
may provide improved performance (e.g., higher throughput and/or
greater reliability) if the additional dimensionalities created by
the multiple transmit and receive antennas are utilized.
[0133] A MIMO system may support time division duplex (TDD) and
frequency division duplex (FDD). In a TDD system, the forward and
reverse link transmissions are on the same frequency region so that
the reciprocity principle allows the estimation of the forward link
channel from the reverse link channel. This enables the access
point to extract transmit beam-forming gain on the forward link
when multiple antennas are available at the access point.
[0134] FIG. 16 illustrates a wireless device 1610 (e.g., an access
point) and a wireless device 1650 (e.g., an access terminal) of a
sample MIMO system 1600. At the device 1610, traffic data for a
number of data streams is provided from a data source 1612 to a
transmit (TX) data processor 1614. Each data stream may then be
transmitted over a respective transmit antenna.
[0135] The TX data processor 1614 formats, codes, and interleaves
the traffic data for each data stream based on a particular coding
scheme selected for that data stream to provide coded data. The
coded data for each data stream may be multiplexed with pilot data
using OFDM techniques. The pilot data is typically a known data
pattern that is processed in a known manner and may be used at the
receiver system to estimate the channel response. The multiplexed
pilot and coded data for each data stream is then modulated (i.e.,
symbol mapped) based on a particular modulation scheme (e.g., BPSK,
QSPK, M-PSK, or M-QAM) selected for that data stream to provide
modulation symbols. The data rate, coding, and modulation for each
data stream may be determined by instructions performed by a
processor 1630. A data memory 1632 may store program code, data,
and other information used by the processor 1630 or other
components of the device 1610.
[0136] The modulation symbols for all data streams are then
provided to a TX MIMO processor 1620, which may further process the
modulation symbols (e.g., for OFDM). The TX MIMO processor 1620
then provides N.sub.T modulation symbol streams to N.sub.T
transceivers (XCVR) 1622A through 1622T. In some aspects, the TX
MIMO processor 1620 applies beam-forming weights to the symbols of
the data streams and to the antenna from which the symbol is being
transmitted.
[0137] Each transceiver 1622 receives and processes a respective
symbol stream to provide one or more analog signals, and further
conditions (e.g., amplifies, filters, and upconverts) the analog
signals to provide a modulated signal suitable for transmission
over the MIMO channel. N.sub.T modulated signals from transceivers
1622A through 1622T are then transmitted from N.sub.T antennas
1624A through 1624T, respectively.
[0138] At the device 1650, the transmitted modulated signals are
received by N.sub.R antennas 1652A through 1652R and the received
signal from each antenna 1652 is provided to a respective
transceiver (XCVR) 1654A through 1654R. Each transceiver 1654
conditions (e.g., filters, amplifies, and downconverts) a
respective received signal, digitizes the conditioned signal to
provide samples, and further processes the samples to provide a
corresponding "received" symbol stream.
[0139] A receive (RX) data processor 1660 then receives and
processes the N.sub.R received symbol streams from N.sub.R
transceivers 1654 based on a particular receiver processing
technique to provide N.sub.T "detected" symbol streams. The RX data
processor 1660 then demodulates, deinterleaves, and decodes each
detected symbol stream to recover the traffic data for the data
stream. The processing by the RX data processor 1660 is
complementary to that performed by the TX MIMO processor 1620 and
the TX data processor 1614 at the device 1610.
[0140] A processor 1670 periodically determines which pre-coding
matrix to use (discussed below). The processor 1670 formulates a
reverse link message comprising a matrix index portion and a rank
value portion. A data memory 1672 may store program code, data, and
other information used by the processor 1670 or other components of
the device 1650.
[0141] The reverse link message may comprise various types of
information regarding the communication link and/or the received
data stream. The reverse link message is then processed by a TX
data processor 1638, which also receives traffic data for a number
of data streams from a data source 1636, modulated by a modulator
1680, conditioned by the transceivers 1654A through 1654R, and
transmitted back to the device 1610.
[0142] At the device 1610, the modulated signals from the device
1650 are received by the antennas 1624, conditioned by the
transceivers 1622, demodulated by a demodulator (DEMOD) 1640, and
processed by a RX data processor 1642 to extract the reverse link
message transmitted by the device 1650. The processor 1630 then
determines which pre-coding matrix to use for determining the
beam-forming weights then processes the extracted message.
[0143] FIG. 16 also illustrates that the communication components
may include one or more components that perform pilot control
operations as taught herein. For example, a pilot control component
1690 may cooperate with the processor 1630 and/or other components
of the device 1610 to receive pilot-related signals from another
device (e.g., device 1650) and transmit pilot reports as taught
herein. Similarly, a pilot control component 1692 may cooperate
with the processor 1670 and/or other components of the device 1650
to send pilot signals to another device (e.g., device 1610) and
receive configuration information from another device as taught
herein. It should be appreciated that for each device 1610 and 1650
the functionality of two or more of the described components may be
provided by a single component. For example, a single processing
component may provide the functionality of the pilot control
component 1690 and the processor 1630 and a single processing
component may provide the functionality of the pilot control
component 1692 and the processor 1670.
[0144] The teachings herein may be incorporated into various types
of communication systems and/or system components. In some aspects,
the teachings herein may be employed in a multiple-access system
capable of supporting communication with multiple users by sharing
the available system resources (e.g., by specifying one or more of
bandwidth, transmit power, coding, interleaving, and so on). For
example, the teachings herein may be applied to any one or
combinations of the following technologies: Code Division Multiple
Access (CDMA) systems, Multiple-Carrier CDMA (MCCDMA), Wideband
CDMA (W-CDMA), High-Speed Packet Access (HSPA, HSPA+) systems, Time
Division Multiple Access (TDMA) systems, Frequency Division
Multiple Access (FDMA) systems, Single-Carrier FDMA (SC-FDMA)
systems, Orthogonal Frequency Division Multiple Access (OFDMA)
systems, or other multiple access techniques. A wireless
communication system employing the teachings herein may be designed
to implement one or more standards, such as IS-95, cdma2000,
IS-856, W-CDMA, TDSCDMA, and other standards. A CDMA network may
implement a radio technology such as Universal Terrestrial Radio
Access (UTRA), cdma2000, or some other technology. UTRA includes
W-CDMA and Low Chip Rate (LCR). The cdma2000 technology covers
IS-2000, IS-95 and IS-856 standards. A TDMA network may implement a
radio technology such as Global System for Mobile Communications
(GSM). An OFDMA network may implement a radio technology such as
Evolved UTRA (E-UTRA), IEEE 802.11, IEEE 802.16, IEEE 802.20,
Flash-OFDM.RTM., etc. UTRA, E-UTRA, and GSM are part of Universal
Mobile Telecommunication System (UMTS). The teachings herein may be
implemented in a 3GPP Long Term Evolution (LTE) system, an
Ultra-Mobile Broadband (UMB) system, and other types of systems.
LTE is a release of UMTS that uses E-UTRA. UTRA, E-UTRA, GSM, UMTS
and LTE are described in documents from an organization named "3rd
Generation Partnership Project" (3GPP), while cdma2000 is described
in documents from an organization named "3rd Generation Partnership
Project 2" (3GPP2). Although certain aspects of the disclosure may
be described using 3GPP terminology, it is to be understood that
the teachings herein may be applied to 3GPP (e.g., Re199, Re15,
Re16, Re17) technology, as well as 3GPP2 (e.g., 1.times.RTT,
1.times.EV-DO Re10, RevA, RevB) technology and other
technologies.
[0145] The teachings herein may be incorporated into (e.g.,
implemented within or performed by) a variety of apparatuses (e.g.,
nodes). In some aspects, a node (e.g., a wireless node) implemented
in accordance with the teachings herein may comprise an access
point or an access terminal.
[0146] For example, an access terminal may comprise, be implemented
as, or known as user equipment, a subscriber station, a subscriber
unit, a mobile station, a mobile, a mobile node, a remote station,
a remote terminal, a user terminal, a user agent, a user device, or
some other terminology. In some implementations an access terminal
may comprise a cellular telephone, a cordless telephone, a session
initiation protocol (SIP) phone, a wireless local loop (WLL)
station, a personal digital assistant (PDA), a handheld device
having wireless connection capability, or some other suitable
processing device connected to a wireless modem. Accordingly, one
or more aspects taught herein may be incorporated into a phone
(e.g., a cellular phone or smart phone), a computer (e.g., a
laptop), a portable communication device, a portable computing
device (e.g., a personal data assistant), an entertainment device
(e.g., a music device, a video device, or a satellite radio), a
global positioning system device, or any other suitable device that
is configured to communicate via a wireless medium.
[0147] An access point may comprise, be implemented as, or known as
a NodeB, an eNodeB, a radio network controller (RNC), a base
station (BS), a radio base station (RBS), a base station controller
(BSC), a base transceiver station (BTS), a transceiver function
(TF), a radio transceiver, a radio router, a basic service set
(BSS), an extended service set (ESS), a macro cell, a macro node, a
Home eNB (HeNB), a femto cell, a femto node, a pico node, or some
other similar terminology.
[0148] In some aspects a node (e.g., an access point) may comprise
an access node for a communication system. Such an access node may
provide, for example, connectivity for or to a network (e.g., a
wide area network such as the Internet or a cellular network) via a
wired or wireless communication link to the network. Accordingly,
an access node may enable another node (e.g., an access terminal)
to access a network or some other functionality. In addition, it
should be appreciated that one or both of the nodes may be portable
or, in some cases, relatively non-portable.
[0149] Also, it should be appreciated that a wireless node may be
capable of transmitting and/or receiving information in a
non-wireless manner (e.g., via a wired connection). Thus, a
receiver and a transmitter as discussed herein may include
appropriate communication interface components (e.g., electrical or
optical interface components) to communicate via a non-wireless
medium.
[0150] A wireless node may communicate via one or more wireless
communication links that are based on or otherwise support any
suitable wireless communication technology. For example, in some
aspects a wireless node may associate with a network. In some
aspects the network may comprise a local area network or a wide
area network. A wireless device may support or otherwise use one or
more of a variety of wireless communication technologies,
protocols, or standards such as those discussed herein (e.g., CDMA,
TDMA, OFDM, OFDMA, WiMAX, Wi-Fi, and so on). Similarly, a wireless
node may support or otherwise use one or more of a variety of
corresponding modulation or multiplexing schemes. A wireless node
may thus include appropriate components (e.g., air interfaces) to
establish and communicate via one or more wireless communication
links using the above or other wireless communication technologies.
For example, a wireless node may comprise a wireless transceiver
with associated transmitter and receiver components that may
include various components (e.g., signal generators and signal
processors) that facilitate communication over a wireless
medium.
[0151] The functionality described herein (e.g., with regard to one
or more of the accompanying figures) may correspond in some aspects
to similarly designated "means for" functionality in the appended
claims. Referring to FIGS. 17-21, apparatuses 1700, 1800, 1900,
2000, and 2100 are represented as a series of interrelated
functional modules. Here, a message receiving module 1702 may
correspond at least in some aspects to, for example, a receiver as
discussed herein. A pilot report generating module 1704 may
correspond at least in some aspects to, for example, a pilot
processor as discussed herein. A pilot report transmitting module
1706 may correspond at least in some aspects to, for example, a
transmitter as discussed herein. A pilot phase value determining
module 1708 may correspond at least in some aspects to, for
example, a pilot processor as discussed herein. A pilot signal
receiving module 1710 may correspond at least in some aspects to,
for example, a receiver as discussed herein. A pilot signature
identifying module 1712 may correspond at least in some aspects to,
for example, a pilot processor as discussed herein. A pilot
signature indicators receiving module 1802 may correspond at least
in some aspects to, for example, a receiver as discussed herein. A
pilot signal transmitting module 1804 may correspond at least in
some aspects to, for example, a transmitter as discussed herein. A
message generating module 1806 may correspond at least in some
aspects to, for example, a pilot processor as discussed herein. A
message transmitting module 1808 may correspond at least in some
aspects to, for example, a transmitter as discussed herein. A pilot
signal strength indication defining module 1810 may correspond at
least in some aspects to, for example, a pilot processor as
discussed herein. A pilot signal strength indication receiving
module 1812 may correspond at least in some aspects to, for
example, a receiver as discussed herein. A message receiving module
1902 may correspond at least in some aspects to, for example, a
receiver as discussed herein. A cell identifier mapping determining
module 1904 may correspond at least in some aspects to, for
example, a handover controller as discussed herein. A handover
target identifying module 1906 may correspond at least in some
aspects to, for example, a handover controller as discussed herein.
A target identified from plurality of cell identifiers determining
module 1908 may correspond at least in some aspects to, for
example, a handover controller as discussed herein. A message
receiving module 2002 may correspond at least in some aspects to,
for example, a receiver as discussed herein. A pilot signature
indicator mapping determining module 2004 may correspond at least
in some aspects to, for example, a handover controller as discussed
herein. A handover target identifying module 2006 may correspond at
least in some aspects to, for example, a handover controller as
discussed herein. A target identified from plurality of cell
identifiers determining module 2008 may correspond at least in some
aspects to, for example, a handover controller as discussed herein.
A pilot signature indicators allocating module 2102 may correspond
at least in some aspects to, for example, a pilot processor as
discussed herein. A message sending module 2104 may correspond at
least in some aspects to, for example, a transmitter as discussed
herein. A pilot signal strength indication defining module 2106 may
correspond at least in some aspects to, for example, a pilot
processor as discussed herein. A more than one pilot signature
indicator determining module 2108 may correspond at least in some
aspects to, for example, a pilot processor as discussed herein. An
unallocated pilot signatures identifying module 2110 may correspond
at least in some aspects to, for example, a pilot processor as
discussed herein.
[0152] The functionality of the modules of FIGS. 17-21 may be
implemented in various ways consistent with the teachings herein.
In some aspects the functionality of these modules may be
implemented as one or more electrical components. In some aspects
the functionality of these blocks may be implemented as a
processing system including one or more processor components. In
some aspects the functionality of these modules may be implemented
using, for example, at least a portion of one or more integrated
circuits (e.g., an ASIC). As discussed herein, an integrated
circuit may include a processor, software, other related
components, or some combination thereof. The functionality of these
modules also may be implemented in some other manner as taught
herein. In some aspects one or more of any dashed blocks in FIGS.
17-21 are optional.
[0153] It should be understood that any reference to an element
herein using a designation such as "first," "second," and so forth
does not generally limit the quantity or order of those elements.
Rather, these designations may be used herein as a convenient
method of distinguishing between two or more elements or instances
of an element. Thus, a reference to first and second elements does
not mean that only two elements may be employed there or that the
first element must precede the second element in some manner. Also,
unless stated otherwise a set of elements may comprise one or more
elements. In addition, terminology of the form "at least one of: A,
B, or C" used in the description or the claims means "A or B or C
or any combination of these elements."
[0154] Those of skill in the art would understand that information
and signals may be represented using any of a variety of different
technologies and techniques. For example, data, instructions,
commands, information, signals, bits, symbols, and chips that may
be referenced throughout the above description may be represented
by voltages, currents, electromagnetic waves, magnetic fields or
particles, optical fields or particles, or any combination
thereof.
[0155] Those of skill would further appreciate that any of the
various illustrative logical blocks, modules, processors, means,
circuits, and algorithm steps described in connection with the
aspects disclosed herein may be implemented as electronic hardware
(e.g., a digital implementation, an analog implementation, or a
combination of the two, which may be designed using source coding
or some other technique), various forms of program or design code
incorporating instructions (which may be referred to herein, for
convenience, as "software" or a "software module"), or combinations
of both. To clearly illustrate this interchangeability of hardware
and software, various illustrative components, blocks, modules,
circuits, and steps have been described above generally in terms of
their functionality. Whether such functionality is implemented as
hardware or software depends upon the particular application and
design constraints imposed on the overall system. Skilled artisans
may implement the described functionality in varying ways for each
particular application, but such implementation decisions should
not be interpreted as causing a departure from the scope of the
present disclosure.
[0156] The various illustrative logical blocks, modules, and
circuits described in connection with the aspects disclosed herein
may be implemented within or performed by an integrated circuit
(IC), an access terminal, or an access point. The IC may comprise a
general purpose processor, a digital signal processor (DSP), an
application specific integrated circuit (ASIC), a field
programmable gate array (FPGA) or other programmable logic device,
discrete gate or transistor logic, discrete hardware components,
electrical components, optical components, mechanical components,
or any combination thereof designed to perform the functions
described herein, and may execute codes or instructions that reside
within the IC, outside of the IC, or both. A general purpose
processor may be a microprocessor, but in the alternative, the
processor may be any conventional processor, controller,
microcontroller, or state machine. A processor may also be
implemented as a combination of computing devices, e.g., a
combination of a DSP and a microprocessor, a plurality of
microprocessors, one or more microprocessors in conjunction with a
DSP core, or any other such configuration.
[0157] It is understood that any specific order or hierarchy of
steps in any disclosed process is an example of a sample approach.
Based upon design preferences, it is understood that the specific
order or hierarchy of steps in the processes may be rearranged
while remaining within the scope of the present disclosure. The
accompanying method claims present elements of the various steps in
a sample order, and are not meant to be limited to the specific
order or hierarchy presented.
[0158] In one or more exemplary embodiments, the functions
described may be implemented in hardware, software, firmware, or
any combination thereof. If implemented in software, the functions
may be stored on or transmitted over as one or more instructions or
code on a computer-readable medium. Computer-readable media
includes both computer storage media and communication media
including any medium that facilitates transfer of a computer
program from one place to another. A storage media may be any
available media that can be accessed by a computer. By way of
example, and not limitation, such computer-readable media can
comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage,
magnetic disk storage or other magnetic storage devices, or any
other medium that can be used to carry or store desired program
code in the form of instructions or data structures and that can be
accessed by a computer. Also, any connection is properly termed a
computer-readable medium. For example, if the software is
transmitted from a website, server, or other remote source using a
coaxial cable, fiber optic cable, twisted pair, digital subscriber
line (DSL), or wireless technologies such as infrared, radio, and
microwave, then the coaxial cable, fiber optic cable, twisted pair,
DSL, or wireless technologies such as infrared, radio, and
microwave are included in the definition of medium. Disk and disc,
as used herein, includes compact disc (CD), laser disc, optical
disc, digital versatile disc (DVD), floppy disk and blu-ray disc
where disks usually reproduce data magnetically, while discs
reproduce data optically with lasers. Combinations of the above
should also be included within the scope of computer-readable
media. It should be appreciated that a computer-readable medium may
be implemented in any suitable computer-program product.
[0159] The previous description of the disclosed aspects is
provided to enable any person skilled in the art to make or use the
present disclosure. Various modifications to these aspects will be
readily apparent to those skilled in the art, and the generic
principles defined herein may be applied to other aspects without
departing from the scope of the disclosure. Thus, the present
disclosure is not intended to be limited to the aspects shown
herein but is to be accorded the widest scope consistent with the
principles and novel features disclosed herein.
* * * * *