HK1151165A

HK1151165A - Identification of target node for wireless handoff

Info

Publication number: HK1151165A
Application number: HK11105062.9A
Authority: HK
Inventors: A‧M‧戈吉奇
Original assignee: 高通股份有限公司
Priority date: 2007-10-12
Filing date: 2008-10-09
Publication date: 2012-01-20

Description

Identification of target nodes for wireless handover

Requesting priority based on 35 U.S.C.S.119

The present application claims priority and benefit from commonly owned U.S. provisional patent application No.60/979,801, attorney docket number 080054P1, filed on 12/10/2007, the disclosure of which is hereby incorporated herein by reference.

Technical Field

The present disclosure relates generally to wireless communications, and more specifically to improving communication performance.

Background

Wireless communication systems are widely deployed to provide various types of communication (e.g., voice, data, multimedia services, etc.) to multiple users. With the rapidly increasing demand for high-rate multimedia data services, challenges arise in implementing efficient and robust communication systems with enhanced performance.

To supplement conventional mobile phone network base stations, such as macro base stations, small-coverage base stations may be deployed (e.g., installed in a user's home) to provide more robust indoor wireless coverage for mobile units. Such small-coverage base stations are generally referred to as access point base stations, home nodebs, or femtocells. Typically, such small-coverage base stations are connected to the internet and the mobile operator's network through DSL routers or cable modems.

As a mobile unit moves through a given geographic area, the mobile unit may need to be handed off from one base station to another base station in the wireless communication system. In such a system, small-coverage base stations may be deployed in an ad-hoc manner. For example, small-coverage base stations may be deployed according to the personal decisions of the owner who installed the base station. Thus, there may be a relatively large number of such small-coverage base stations within a given area to which a mobile unit may be handed off. Therefore, there is a need for an efficient handover method in a wireless communication system in which a large number of base stations are deployed.

Disclosure of Invention

The following presents a simplified summary of exemplary aspects of the invention. It should be understood that any reference herein to a term aspect may refer to one or more aspects of the present invention.

In some aspects, the present invention relates to identifying an access point to which an access terminal is to be handed off. For example, when an access terminal detects a signal from an access point, confusion may arise as to the identity of the access point. In this case, identifying the access point to which the access terminal is to be handed over may include determining which access point of a set of access points within a given area transmitted a signal detected by the access terminal.

In some aspects, the present disclosure relates to identifying a set of candidate access points for a handover operation. For example, the network node may receive a message from the access terminal indicating that the access terminal received a signal having a certain characteristic (e.g., a particular phase offset). In this case, the network node may define a set of candidate access points by deciding which of the access points in the vicinity of the access terminal generated a signal having the determined characteristic.

In some aspects, the present invention relates to identifying an access point for a handover operation from signals received at the access point. For example, each access point in the candidate set of access points is instructed to attempt to detect signals from the access terminal and send a report to a network node (if any) indicating the signals received from the access point. The network node may then determine which access point in the candidate set is to be used for a handover operation. For example, the access point that received the signal with the highest signal strength from the access terminal may be selected as the target access point for handover.

In some aspects, the access points in the candidate set may include femto nodes having smaller coverage than that provided by macro access points. In some aspects, the access points may be deployed in an ad hoc network.

Drawings

These and other exemplary aspects of the present invention are described in the following detailed description and appended claims, and in the accompanying drawings, in which:

fig. 1 is a simplified block diagram of several exemplary aspects of a communication system for performing a handover operation in accordance with the teachings herein;

fig. 2 is a simplified block diagram of a wireless communication system including an access point and an access terminal;

fig. 3 is a simplified block diagram of a wireless communication system including a femto node;

fig. 4 is a simplified block diagram illustrating an exemplary coverage area for wireless communications;

FIGS. 5A and 5B are flow diagrams illustrating aspects of example operations that may be performed to perform a handover operation according to the teachings herein;

fig. 6 is a simplified block diagram of several exemplary components of a node for performing a handover operation in accordance with the teachings herein.

FIG. 7 is a simplified block diagram of several exemplary aspects of a communications component; and

fig. 8 and 9 are simplified block diagrams of several exemplary aspects of an apparatus for facilitating a communication handoff as taught herein.

In accordance with common practice, the various features shown in the drawings are not drawn to scale. Accordingly, the dimensions of the various features may be arbitrarily expanded or reduced for clarity. Moreover, 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 are used to denote like features throughout the specification and drawings.

Detailed Description

Various aspects of the invention are described below. It will 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. In light of the teachings herein, those skilled in the art will appreciate that an aspect disclosed herein may be implemented independently of any other aspects and that two or more aspects may be combined in various ways. For example, an apparatus may be implemented or a method may be practiced using any of several aspects described herein. Further, such an apparatus or such a method may be implemented or realized by using 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.

Fig. 1 illustrates several nodes (e.g., portions of a communication network) in an example communication system 100. For ease of explanation, various aspects of the invention will be described in the context of one or more network nodes, access points, and access terminals communicating with each other. It should be understood that the teachings herein may be applied to other types of devices or other similar devices that are referenced using other terminology.

Access points 102, 104, and 106 in system 100 provide one or more services (e.g., network connections) to one or more wireless terminals (e.g., access terminal 108) installed or roaming in an associated geographic area. Further, access point 102 can communicate with one or more network nodes (shown as network node 10 for convenience) to facilitate wide area network connectivity. Such a network node may take various forms, such as one or more radio and/or core network entities (e.g., a mobility manager such as a base station controller, a mobility management entity, a radio network controller, etc.).

When the access terminal 108 is in a connected state (e.g., during an active call), the access terminal 108 will be served by an access point (e.g., macro access point 102) in the system 100. However, as the access terminal 108 moves closer to the access point 104, the access terminal 108 may receive a stronger signal from the access point 104 than from the access point 102. Therefore, there is a need to handoff an access terminal 108 from an access point 102 (e.g., a source access point) to an access point 104 (e.g., a target access point) to maintain the best possible wireless signal quality for the access terminal 108.

In practice, however, the identity of the access point transmitting the signal received by the access terminal 108 may not be readily known. For example, in some scenarios, multiple access points within a given area transmit signals using similar parameters, and therefore signals (e.g., pilots or beacons) transmitted by those access points are not readily distinguishable.

Fig. 1 and the following discussion illustrate one scheme for identifying an access point 104 to which an access terminal 108 may be handed off. When the access terminal 108 is in the connected state, the access terminal 108 may analyze signals it receives from any nearby signal sources. Here, the access terminal 108 may identify different signals from different sources based on one or more characteristics of the received signals. For example, in some implementations different communication nodes may transmit signals using different phase offsets of pseudo-random number ("PN") sequences. The access terminal 108 may also measure a particular characteristic of each signal, such as received signal strength. The access terminal may report such information to the network node 110 to enable the network node 110 to determine whether the access terminal 108 should handover and/or to facilitate handover by coordinating handover with the source access point and the target access point.

Network node 110 may cooperate with one or more access points in system 100 to determine the identity of the access point transmitting the signal reported by access terminal 108. For example, the access point ("AP") candidate set identifier 112 may identify a set of candidate target access points that may be transmitting the signal. As will be described in more detail below, such a candidate set may be selected by: access points that transmit signals having the same characteristics (e.g., phase offsets) as signals received by access terminal 108 are identified as being in the vicinity of macro access point 102 (e.g., as indicated by neighbor cell information for all femto access points that have macro access point 102 as a neighbor). In this way, the candidate set identifier 112 may make this determination based on measurement report information provided by the access terminal 108 and neighbor cell information for the femto cell stored in the system configuration database. Once the candidate set is identified, the candidate set identifier 112 may send a request to each access point in the candidate set to instruct the access points to attempt to acquire an uplink signal from the access terminal 108.

In response to the acquisition request, each access point in the candidate set may attempt to acquire and monitor the uplink signal of the access terminal 108 and report back to the network node 110. For example, upon receiving an acquisition request, the signal processor 114 of the access point 104 may begin searching for signals from the access terminal 108 on the uplink. If an uplink signal is detected, the signal strength report generator 116 may generate a report indicating the corresponding received signal strength and send the report back to the network node 110. To reduce the complexity of fig. 1, components 114 and 116 are depicted only for access point 104. It should be understood that these or similar components may be incorporated into other access points of system 100, such as access point 106.

The target identifier 118 AT the network node 110 processes responses (e.g., signal strength reports) received from candidate access points that have reported detecting uplink signals from the AT 108 to identify the access point that sent the signal reported by the access terminal 108. For example, as detailed below, the identified access point corresponds to the access point that reported the highest received signal strength on the uplink from the access terminal 108. Once this access point is identified, network node 110 may send an appropriate handover request message to initiate handover of access terminal 108 from a source access point (e.g., access point 102) to a target access point (e.g., access point 104).

In some aspects, such a handover scheme may be used in a network that includes macro coverage (e.g., a large area cellular system such as a 3G network, commonly referred to as a macro cell network or WAN) and smaller coverage (e.g., a residential-based or building-based network environment, commonly referred to as a LAN). Here, as an access terminal ("AT") moves through such a network, the access terminal may be served AT a particular location by an access point that provides macro coverage while the access terminal is served AT other locations by an access point that provides smaller coverage. In some aspects, smaller coverage nodes may be used to provide increased capacity growth, indoor coverage, and different services (e.g., to obtain a more robust user experience). In this case, there may be a relatively large number of small coverage nodes within a given particular region. Thus, in a system having a limited number of transmission parameter values (e.g., phase offsets) that may be used by the nodes, the likelihood of two or more of the nodes using the same parameter values may increase. In such a case, the teachings herein may be used to differentiate between nodes using the same parameters in order to identify a target node for a handover operation.

In the description herein, a node that provides coverage over a relatively large area may be referred to as a macro node, while a node that provides coverage over a relatively small area (e.g., a residence) may be referred to as a femto node. It should be understood that the teachings herein may be applied to nodes associated with other types of coverage areas. For example, a pico node may provide coverage over an area that is smaller than a macro area and larger than a femto area (e.g., coverage within a commercial building). In various applications, other terminology may be used to refer to macro nodes, femto nodes, or other types of nodes. For example, a macro node may be configured or referred to as an access node, base station, access point, enodeb, macro cell, and so on. Further, a femto node 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., divided into) one or more cells or sectors. The cells or sectors associated with a macro, femto, or pico node may be referred to as a macro, femto, or pico cell, respectively. Simplified examples of how femto nodes may be deployed in a network will be described with reference to fig. 2-4.

Fig. 2 illustrates a wireless communication system 200 for supporting multiple users in which the teachings herein may be implemented. The system 200 provides communication for a plurality of cells 202, such as macro cells 202A-202G, where each cell is served by a respective access point 204 (e.g., access points 204A-204G). As shown in fig. 2, over time, access terminals 206 (e.g., access terminals 206A-206L) can be distributed at various locations throughout the system. For example, each access terminal 206 may communicate with one or more access points 204 on a forward link ("FL") and/or a reverse link ("RL") at a given moment, depending on whether the access terminal 206 is active and in soft handoff. The wireless communication system 200 may provide service over a large geographic area. For example, the macro cells 202A-202G may cover several blocks of neighborhood or several square miles in a rural environment.

Fig. 3 illustrates an example communication system 300 that deploys one or more femto nodes within a network environment. In particular, the system 300 includes a plurality of femto nodes 310 (e.g., femto nodes 310A and 310B) installed within a relatively small-coverage network environment (e.g., in one or more user residences 330). Each femto node 310 can be coupled to a wide area network 340 (e.g., the internet) and a mobile operator core network 350 through a DSL router, cable modem, wireless link, or other connectivity means (not shown).

The owner of the femto node 310 may subscribe to mobile services, such as 3G mobile services provided through the mobile operator core network 350. Further, the access terminal 320 is capable of operating in both macro environments and smaller coverage (e.g., residential) network environments. In other words, depending on the current location of the access terminal 320, the access terminal 320 may be served by a macro cell access point 360 associated with the mobile operator core network 350 or by any one of the femto nodes in the set of femto nodes 310 (e.g., the femto nodes 310A and 310B located within the respective user residence 330). For example, when a user is outdoors, it may be served by a standard macro access point (e.g., access point 360), and when the user is near or at home, it may be served by a femto node (e.g., node 310A). Here, the femto node 310 may be backward compatible with legacy access terminals 320.

Fig. 4 shows an example of an overlay 400 in which several tracking areas 402 (or routing areas or location areas) are defined, each area comprising several macro coverage areas 404. Here, the coverage areas associated with the tracking areas 402A, 402B, and 402C are drawn with wide lines and the macro coverage area 404 is represented by a hexagon. The tracking area 402 also includes a femto coverage area 406. In this example, each femto coverage area 406 (e.g., femto coverage area 406C) is depicted as being in a macro coverage area 404 (e.g., macro coverage area 404B). It should be understood that the femto coverage area 406 may not be entirely within the macro coverage area 404. In addition, one or more pico coverage areas (not shown) may also be defined within a given tracking area 402 or macro coverage area 404.

In practice, a large number of femto coverage areas 406 may be defined within a given tracking area 402 or macro coverage area 404. Thus, when an access terminal detects a signal in such a network, the teachings herein can be used to efficiently identify which access point (e.g., which femto node) sent that signal. Once this access point is identified, the access terminal may handoff to the access point, if desired.

Additional details regarding handover operations that may be performed in accordance with the teachings herein will be described below with reference to the flowcharts of 5A and 5B. In the example of fig. 1, these operations may involve an access terminal 108, the access terminal 108 initially being served by a macro access point 102 and then handing off to a femto node (e.g., access point 104). The term "hand-in" refers to a handover from a macrocell to a femtocell. It should be understood that the teachings herein may be applicable to other types of handoff operations (e.g., handoff from one femto node to another femto node).

A network including femto nodes may include one or more network entities capable of facilitating macro-to-femto interoperability. For example, such an entity can maintain information (e.g., connectivity, location, and configuration information) for each femto node in the network. In various implementations, such entities may be implemented as stand-alone components or integrated into other general-purpose network components. For convenience, this functionality is described in the following discussion as being implemented in the network node 110.

For ease of illustration, the operations of fig. 5A and 5B (or any other operations taught or discussed herein) may be described as being performed by specific components (e.g., components in system 600 and/or system 100 as shown in fig. 6). It should be understood that these operations may be performed by other types of components and may be performed using a different number of components. It should also be understood that one or more of the operations described herein may not be used in a given implementation.

Fig. 6 illustrates several example components that may be included into an access terminal 108, an access point 102, a network node 110, and an access point 104 in accordance with the teachings herein. It should be understood that the components shown for a given one of the nodes may also be included in other nodes in the communication system. For example, access point 106 may include similar components to those described for access point 104 or access point 102. It should be understood that a node may comprise one or more given components, e.g., an access point may comprise multiple receivers to operate on multiple frequencies and serve multiple access terminals simultaneously.

Access terminal 108, access point 102, network node 110, and access point 104 include transceivers 602, 604, 606, and 608, respectively, for communicating with each other and with other nodes. Each transceiver includes a respective transmitter (transmitters 610, 612, 614, and 616) for transmitting signals (e.g., messages) and a respective receiver (receivers 618, 620, 622, and 624) for receiving signals.

The node in fig. 6 also includes other components that may be used in conjunction with handover operations as taught herein. For example, the nodes include respective communication controllers 626, 628, 630, and 632 for managing communications (e.g., sending and receiving messages/directives) with other nodes, as well as for providing other related functionality as taught herein. These nodes may include respective handover controllers 634, 636, 638 and 640 for facilitating handover operations and for providing other related functionality as taught herein. Exemplary operation of the other components in fig. 6 is as follows. For ease of illustration, particular nodes are depicted in fig. 6 as having particular functionality with respect to supporting handoffs. It should be understood that one or more of the illustrated components may be used in another of these nodes or in some other node.

Referring now to fig. 5A, as shown at block 502, femto nodes in the system transmit pilots (or beacons) so that any access terminal in the vicinity can detect the presence of a femto node. As described above, a relatively large number of femto nodes may be deployed within a macro coverage area. Thus, there may be some reuse of communication resources between neighboring femto nodes. For example, a given network may assign a fixed number (e.g., 64) of PN phase offsets. Reuse of the phase offset may occur when there are more femto nodes within a given area (e.g., within the coverage area of a macro AP) than phase offsets. As such, multiple femto nodes may transmit signals with similar characteristics within a given area.

Femto nodes in a network may be configured to operate on one or more frequencies. For example, in some implementations, all femto nodes (or all restricted femto nodes) within an area may operate on a designated femto channel (or femto channels). Due to the particular configuration, a single frequency or one or more frequencies may overlap with one or more frequencies used by the macro access point. Accordingly, provisions may be made to ensure that an access terminal operating on a particular frequency on the macro node may receive at least a portion of a beacon transmitted by the femto node. For example, a femto node can employ frequency hopping such that at different times the femto node transmits a beacon on each of a set of defined frequencies (e.g., corresponding to a femto channel and a macro channel).

As shown at block 504, the access terminal 108 (e.g., receiver 618) can periodically monitor the downlink pilot signal. While in an active call, the access terminal 108 searches for and monitors the downlink pilot almost continuously. In conjunction with such monitoring, the access terminal 108 may identify one or more characteristics associated with any detected signals. For example, the access terminal 108 may monitor for signals having a particular PN sequence phase offset based on neighbor reports received from the serving macro access point 102. If such signals are detected, the access terminal 108 may measure the corresponding received signal strengths of the signals.

As indicated at block 506, one or more conditions may be specified as potential triggers for a handover operation. For example, if the received signal strength of the pilot signal is greater than or equal to a threshold, a potential handoff may be indicated.

As shown at block 508, the access terminal 108 (e.g., measurement report generator 642) can generate a report related to a downlink signal received by the access terminal 108 and provide the report to the access point 102. Access point 102 may then forward the information to the network (e.g., network node 110). As described above, the measurement report may include information such as the received signal strength and phase offset of a given signal. For example, the report includes pilot strength measurements that include a received signal strength value (e.g., E) for each pilot received by the access terminal 108_C/I₀) The PN sequence offset for all pilots received by the access terminal 108, and the PN sequence offset for the access terminal 108 (e.g., which the access terminal 108 uses as a timing reference).

As shown at block 510 and 514, access point 102 and/or network node 110 may selectively monitor signals or other related conditions associated with access terminal 108 to determine whether a handover should occur or to determine an optimal timing for the handover. For example, the macro cellular network may monitor channel performance at the macro level and/or the femto level. In the example of fig. 6, condition monitor 644 of access point 102 may monitor channel performance conditions, such as power levels and/or frame errors associated with communication with access terminal 108. Here, rather than immediately switching as a result of the threshold condition being met at block 506, the macro network may monitor conditions over a period of time to ensure, for example, that the handover trigger is not a transient event. Further, the macro network may choose not to perform a handoff operation if acceptable signal conditions exist between the access point 102 and the access terminal 108. For example, if there is a low error rate and/or a high quality of service on the link between access point 102 and access terminal 108, then a handoff should not occur. Likewise, if the signal strength of the signal received by the access terminal 108 from the access point 102 is sufficiently high (e.g., higher than the signal strength from the measurement report in block 508), then a handover should not be performed.

Thus, as shown at block 514, the macro network (e.g., access point 102) may continue to monitor the selected conditions until it determines whether a handoff should be performed. The access terminal 108 may remain within the macro network if a decision is made not to perform a handoff operation.

As shown at block 516, if a handover operation is decided upon, the network node 110 (e.g., the candidate set identifier 646) may analyze the measurement reports received from the access terminal 108 to identify one or more signal characteristics associated with the signals received by the access terminal 108. In some implementations, the network node 110 can determine that the signal was transmitted by the femto node based on one or more of these characteristics. For example, a known subset of PN phase offsets available in the macro network may be used exclusively by femto nodes.

If it is determined that the access terminal 108 has received a signal from a femto node, the candidate set identifier 646 will identify a subset of femto nodes in the system that have transmitted the signal. For example, network node 110 may maintain or obtain information (e.g., neighbors and other configurations of access points) indicating where femto nodes are deployed in the network. Accordingly, the candidate set identifier 646 can utilize the information to identify femto nodes deployed, for example, in the vicinity of a currently serving access point (e.g., access point 102) of the access terminal 108. In this manner, the network node 110 can identify a subset of femto nodes that are in the vicinity of the access terminal 108 and thus can generate signals that the access terminal 108 can receive.

In addition, the candidate set identifier 646 can determine which identified nodes generated signals that match the signals received by the access terminal 108. For example, the network node 110 can maintain or obtain information indicating the PN phase offset (or other matching parameter) used by each femto node in the network. In this way, the candidate set identifier 646 may utilize this information to more accurately identify the femto node that generated the signal. According to the above test, a set of target femto nodes as candidates is defined for the target femto node as the access terminal 108.

If any of the tests described above indicate that only a single femto node generated the signal (i.e., the candidate set includes only one femto node), the operational flow may proceed to block 526 for subsequent handover operations for the target femto node. Alternatively, if more than one candidate femto node is identified in block 516, the operational flow proceeds to block 518 and 524 to identify a single target femto node.

As shown at block 518, the network node 110 sends a message to each femto node in the candidate set, where each message requests that the femto node attempt to process (e.g., acquire) an uplink signal from the access terminal 108. In some aspects, these requests may take the form of a handoff request message that is used to inform the femto node of a potential impending handoff and thereby cause the femto node to monitor the uplink for handoff messages from the access terminal 108.

In some aspects, the requests may include information related to channel parameters for connections assigned to the access terminal 108 to enable the femto node to handle uplink transmissions from the access terminal 108. For example, the request may indicate a scrambling code used by the access terminal 108 on the uplink. Further, if a given femto node is operating on a different frequency than the access terminal 108, the request may indicate the operating frequency (e.g., carrier frequency) of the access terminal 108.

Additionally, in some implementations, the request can include information regarding how the femto node responded to the request. For example, the femto node can be instructed to reply to the request regardless of whether the femto node successfully acquired the signal from the access terminal 108. Further, the femto node can be instructed to reply with specific information related to any signal acquired. It should be appreciated that in other implementations, the manner in which the femto node should respond to the request can be preconfigured or otherwise controlled.

Upon receiving the request, each femto node in the candidate set attempts to acquire uplink transmissions from the access terminal 108, as shown at block 520. For example, an acquisition request processor 648 of an access point 104 can instruct the receiver 624 to monitor signals on the uplink and instruct the signal processor 650 to process any signals received by the receiver 624 in accordance with parameters (e.g., scrambling code, frequency, etc.) received in the request. For example, the signal processor 650 may attempt to demodulate and decode the received signal. Further, if access point 104 successfully acquires a signal from access point 108, signal processor 650 may generate information related to the acquired signal. For example, in some implementations, an indication of signal energy received from the access terminal 108 is generated.

Depending on the results of the acquisition operation, an acquisition response generator 652 (e.g., corresponding to the report generator 116) may send a response to the network node 110 indicating whether the access point 104 successfully acquired the (e.g., decoded) signal from the access terminal 108. For example, in some implementations, the response is only sent if the access point 104 successfully acquires a signal from the access terminal 108. In other implementations, a negative acknowledgement may be sent if the access point does not acquire a signal from the access terminal 108. In some implementations, the response may include information related to the acquired signal (e.g., received signal strength).

As shown at block 522, the network node 110 receives a report from one or more femto nodes in the candidate set of femto nodes. If only one response is received, it can be assumed that the femto node that sent the response is the only node that has sent the signal received by the access terminal 108. In this case, the operational flow may proceed to block 526 for a subsequent handover operation.

Alternatively, if more than one candidate femto node indicates that it acquired a signal from the access terminal 108, operational flow proceeds to block 524 to identify a single target femto node. In some implementations, the identification of the target femto node is based on signals received by each femto node from the access terminal 108. For example, the handover target identifier 654 of the network node 110 is used to select a target femto node based on the magnitude of the received signal strength reported by the candidate femto node. Here, it may be assumed that the femto node reporting the highest received signal strength is closer to the access terminal 108 than other femto nodes. Accordingly, it may be determined that the femto node is the best candidate femto node for a handoff operation.

As shown at blocks 526 and 528, in some implementations, the network (e.g., authentication controller 656) can verify whether the access terminal 102 is authorized to access the identified femto node. If the access terminal 102 is not authorized (block 530), the network may terminate the handover of the access terminal 108, which may result in the access terminal 108 remaining within the macro network. In some cases, the network may switch the access terminal 108 to operate on a different frequency (e.g., macro-only frequency). This may, for example, mitigate potential interference between the unauthorized access terminal 108 and the identified femto node.

For example, where the identified femto node is restricted in some manner, the authentication operations in blocks 526 and 528 may be used. For example, a given femto node may be configured to provide only certain services to certain access terminals. In deployments with so-called restricted (or closed) associations, a given access terminal is served only by the macrocell mobile network and a defined set of femto nodes (e.g., femto nodes 310 residing within respective user residences 330, as shown in fig. 3). For example, each femto node 310 in fig. 3 may be configured to serve associated access terminals 320 (e.g., access terminal 320A), and optionally guest access terminals 320 (e.g., access terminal 320B). In other words, access to femto nodes 310 is restricted such that a given access terminal 320 may be served by a designated (e.g., home) set of femto nodes 310 but may not be served by any unspecified femto nodes 310 (e.g., neighbor's femto nodes 310).

In some aspects, a restricted femto node (also referred to as a closed subscriber group home node B) is a type of femto node that provides service to a defined restricted set of access terminals. The set may be expanded temporarily or permanently as desired. In some aspects, a closed subscriber group ("CSG") may be defined as a set of access points (e.g., femto nodes) that share a common access control list of access terminals. In some implementations, the nodes are restricted to not provide at least one of the following for at least one node: signaling, data access, registration, paging, or service.

Thus, various relationships may exist between a given femto node and a given access terminal. For example, from the perspective of an access terminal, an open femto node refers to a femto node that has an open association (e.g., the femto node allows access to any access terminal). A restricted femto node refers to a femto node that is restricted in some manner (e.g., restricted to association and/or registration). A home femto node refers to a femto node on which an access terminal is authorized to access and operate (e.g., provide permanent access for a defined set of one or more access terminals). A guest femto node refers to a femto node on which an access terminal is temporarily authorized to access or operate. A foreign femto node refers to a femto node (except for possible emergency situations, such as 911 calls) on which an access terminal is not authorized to access or operate.

From the perspective of a restricted femto node, a home access terminal refers to an access terminal that is authorized to access the restricted femto node (e.g., the access terminal has permanent access to the femto node). A guest access terminal refers to an access terminal that has temporary access to a restricted femto node (e.g., restricted by a deadline, a time of use, a byte, a connection count, or some other criteria or criteria). An alien access terminal refers to an access terminal that does not have permission to access a restricted femto node except for possible emergency situations such as 911 calls (e.g., an access terminal that does not have credentials or permission to register with a restricted femto node).

Referring again to fig. 5B, if the access terminal 102 is authorized to access the identified access point in block 528, the operational flow proceeds to blocks 532 and 534 for a handoff operation. Here, one or more handover controllers 634, 636, 638, and 640 may cooperate to inform the access terminal 108 of the impending handover and the identity (and optionally operating frequency) of the target femto node (block 532), provide appropriate information to the target femto node (e.g., send a handover request to the access point 104), and complete the handover (block 534). For example, the network node 110 may send a handoff direction message to the access terminal 108 where the only member in the active pilot set is the target femto node (e.g., hard handoff on the same frequency). The access terminal 108 and the target femto node begin demodulating on the link between the nodes and the access terminal 108 sends a handoff completion message to the target femto node.

Thus, the present invention discloses efficient techniques for providing handovers between communication nodes. Advantageously, these techniques may be used with legacy terminals that are already operational, as no changes to the wireless signaling procedures are required to implement these techniques. In addition, these techniques allow for maximum use of femto nodes that a given terminal is authorized to use. Further, these techniques allow for relatively fast handovers to frequencies other than those used by the femto node when the access terminal is not authorized to access the femto node.

It should be understood that the teachings herein may be implemented in various types of communication devices. In some aspects, the teachings herein may be implemented in a wireless device deployed in a multiple access communication system that simultaneously supports communication for multiple wireless access terminals. Here, each terminal can communicate with one or more access points via transmissions on 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. Such communication links may be established through a single-in single-out system, a multiple-in multiple-out ("MIMO") system, or other type of system.

MIMO systems employing multiple (N)_TMultiple) transmitting antenna and multiple (N)_RAnd) receiving antennas for data transmission. From N_TA transmitting antenna and N_RThe MIMO channel formed by the receiving antennas can be decomposed into N_SIndependent channels, also called spatial channels, in which N_S≤min{N_T，N_R}。N_SEach of the individual channels corresponds to a dimension. MIMO systems may provide improved performance (e.g., higher throughput and/or higher reliability) if the additional dimensionalities created by the multiple transmit and receive antennas are utilized.

MIMO systems support time division duplexing ("TDD") and frequency division duplexing ("FDD"). In a TDD system, the forward link transmission and the reverse link transmission are in the same frequency domain, such 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 beamforming gain on the forward link when multiple antennas are available at the access point.

The teachings herein may be incorporated into a node (e.g., a device) that employs various means for communicating with at least one other node. FIG. 7 depicts several example components that facilitate inter-node communication. Specifically, fig. 7 illustrates a wireless device 710 (e.g., an access point) and a wireless device 750 (e.g., an access terminal) of a MIMO system 700. At the device 710, traffic data for a number of data streams is provided from a data source 712 to a transmit ("TX") data processor 714.

In some aspects, each data stream is transmitted over a respective transmit antenna. TX data processor 714 formats, codes, and interleaves the data stream based on a particular coding scheme selected for that data stream to provide coded data.

The coded data for each data stream is 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 selected modulation scheme (e.g., BPSK, QSPK, M-PSK, or M-QAM) 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 processor 730. A data memory 732 may store program code, data, and other information used by the processor 730 or other components of the device 710.

The modulation symbols for all data streams are then provided to a TX MIMO processor 720, and the TX MIMO processor 720 further processes the processed modulation symbols (e.g., for OFDM). TX MIMO processor 720 then provides N_TA stream of modulation symbols to N_TAnd transceivers ("XCVR") 722A through 722T. In some aspects, TX MIMO processor 720 applies beamforming weights to the symbols of the data streams and to the antenna from which the symbol is being transmitted.

Each transceiver 722 receives and processes a respective symbol stream to provide one or more analog signals, and further processes (e.g., amplifies, filters, and upconverts) the analog signals to provide a modulated signal suitable for transmission over the MIMO channel. Then, N from transceivers 722A through 722T_TEach modulated signal being from N_TThe antennas 724A through 724T transmit.

At apparatus 750, the transmitted modulated signal is represented by N_REach antenna 752A to 752R is connectedEach received signal from each antenna 752, received through 754R, is then provided to a respective transceiver 754A ("XCVR"). Each transceiver 754 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.

A receive ("RX") data processor 760 then couples the slave N signals according to a particular receiver processing technique_RA stream of symbols received by a transceiver 754 is received and processed to provide N_TA stream of "detected" symbols. The RX data processor 760 then demodulates, deinterleaves, and decodes each detected symbol stream to recover the traffic data for the data stream. The processing by RX data processor 760 is complementary to that performed by TX MIMO processor 720 and TX data processor 714 at the device 710.

A processor 770 periodically decides which pre-coding matrix to use (discussed below). Processor 770 generates a reverse link message that includes a matrix index portion and a rank value portion. A data memory 772 may store program codes, data, and other information used by processor 770 or other components of device 750.

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 738, which receives traffic data for a number of data streams from a data source 736, modulated by a modulator 780, processed by transceivers 754A through 754R, and transmitted back to device 710.

At the device 710, the modulated signals from the device 750 are received by the antennas 724, conditioned by the transceivers 722, demodulated by a demodulator ("DEMOD") 740, and processed by a RX data processor 742 to extract the reverse link message transmitted by the device 750. Processor 730 then determines which pre-coding matrix to use for determining the beamforming weights then processes the extracted message.

Fig. 7 also shows that the communication means comprises one or more means for performing the handover operations taught herein. For example, handover control component 790 may cooperate with 730 the processor and/or other components of device 710 to send handover-related signals to or receive handover-related signals from another device (e.g., device 750), as taught herein. Likewise, handover control component 792 may cooperate with processor 770 and/or other components of device 750 to send and receive handover-related signals to and from another device (e.g., device 710). It should be understood that the functionality of two or more of the described components may be provided by a single component for each of devices 710 and 750. For example, a single processing element provides the functionality of the handover control element 790 and the processor 730, and a single processing element provides the functionality of the handover control element 792 and the processor 770.

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 available system resources (e.g., by specifying one or more bandwidths, transmit powers, encoding, interleaving, and so forth). For example, the teachings herein may be applied to any one or combination of the following technologies: code division multiple access ("CDMA") systems, multi-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, WCDMA, TDSCDMA, among others. The CDMA network may implement techniques such as universal terrestrial radio access ("UTRA"), CDMA2000, or other techniques. UTRA includes W-CDMA and low chip rate ("LCR"). cdma2000 technology covers IS-2000, IS-95 and IS-856 standards. TDMA networks may implement radio technologies such as global system for mobile communications ("GSM"). OFDMA network can realize such as evolutionUTRA(“E-UTRA”)、IEEE 802.11、IEEE 802.16、IEEE 802.20、And the like. UTRA, E-UTRA and GSM are parts of the Universal Mobile Telecommunications System ("UMTS"). The teachings herein may be implemented in 3GPP long term evolution ("LTE") systems, ultra mobile broadband ("UMB") systems, and other types of systems. LTE is a release of UMTS that uses E-UTRA. While 3GPP terminology may be employed to describe certain aspects of the present invention, it should be understood that the teachings herein are applicable to 3GPP (Re199, Re15, Re16, Re17) technology as well as 3GPP2(IxRTT, 1xEV-DO RelO, RevA, RevB) technology and other technologies.

The teachings herein may be incorporated into (e.g., implemented in or performed by) multiple apparatuses (e.g., nodes). In some aspects, a node (e.g., a wireless node) implemented in accordance with the teachings herein comprises an access point or an access terminal.

An access terminal includes, for example, (implemented or referred to as) user equipment, subscriber station, subscriber unit, mobile station, mobile node, remote station, remote terminal, user agent, user device, or other terminology. In some implementations, an access terminal includes 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 other suitable processing device connected to a wireless modem. Accordingly, one or more aspects taught herein may include a connection to a telephone (e.g., a cellular telephone or smart phone), a computer (e.g., a notebook computer), a portable communication device, a portable computing device (e.g., a personal digital 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 for communicating over a wireless medium.

An access point includes (implemented or referred to as) node B, e node B, radio network controller ("RNC"), base station ("BS"), radio base station ("RBS"), base station controller ("BSC"), base transceiver station ("BTS"), transceiver function ("TF"), radio transceiver, radio router, basic service set ("BSs"), extended service set ("ESS"), or other similar terminology.

In some aspects, a node (e.g., an access point) comprises an access node of a communication system. Such an access node may provide a connection to a network (e.g., a wide area network such as the internet or a cellular network), for example, through a wired or wireless communication link to the network. Thus, an access node may enable another node (e.g., an access terminal) to access a network or perform other functions. Further, it should be understood that one or both of the nodes may be portable or, in some cases, relatively non-portable.

Additionally, it should be understood that wireless nodes may be capable of transmitting and/or receiving information in a non-wireless manner (e.g., through a wired connection). Thus, the receivers and transmitters described herein include appropriate communication interface components (e.g., electrical or optical interface components) to communicate over a non-wireless medium.

The wireless nodes may communicate via one or more wireless communication links based on or supporting any suitable wireless communication technology. For example, in some aspects, a wireless node is associated with a network. In some aspects, the network comprises a local area network or a wide area network. The wireless device may support or use one or more wireless communication technologies, protocols, or standards, such as those discussed herein (e.g., CDMA, TDMA, OFDM, OFDMA, WiMAX, or Wi-Fi, etc.). Likewise, the wireless node may support or use one or more corresponding modulation or multiplexing schemes. The wireless node thus includes appropriate components (e.g., air interface) to establish and communicate over one or more wireless communication links using the above-described or other wireless communication techniques. For example, a wireless node includes a wireless transceiver associated with transmitter and receiver components including various components (e.g., signal generators and signal processors) that facilitate communication over a wireless medium.

The components described herein may be implemented in a variety of ways. Referring to fig. 8 and 9, the apparatus 800 and 900 are represented as a series of interrelated functional blocks. In some aspects, the functions of these functional blocks may be implemented as a processing system including one or more processor components. In some aspects, these functional blocks may be implemented, for example, using at least a portion of one or more integrated circuits (e.g., an ASIC). As described above, an integrated circuit includes a processor, software, other related components, or some combination thereof. The functionality of these blocks may also be implemented in other ways as taught herein.

The devices 800 and 900 include one or more modules that can perform one or more of the functions described above with respect to the various figures. For example, candidate identification module 802 corresponds to a candidate set identifier, such as described herein. The sending module 804 corresponds to, for example, a candidate set identifier as described herein. The receiving module 806 corresponds to, for example, an object identifier as described herein. The access point identification module 808 corresponds to, for example, an object identifier as described herein. The receiving module 902 corresponds to, for example, a communication controller as described herein. The processing module 904 corresponds to, for example, a signal processor as described herein. The transmitting module 906 corresponds to, for example, a communication controller as described herein.

It should be understood that any reference to elements herein using a name such as "first," "second," etc., does not generally limit the order or number of such elements. Rather, these names may be used herein as a convenient way to distinguish between two or more elements or instances of elements. Thus, reference to a first element and a second element does not mean: only two elements may be used or a first element must somehow precede a second element. Further, unless specified otherwise, a group of elements includes one or more elements. Furthermore, the term "A, B or at least one of C" used in the specification or claims means "A or B or C or a combination of these elements".

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.

Those of skill would further appreciate that 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 other techniques), various forms of program or design code incorporating instructions (which are referred to herein, for convenience, as "software" or a "software module"), or combinations of both. To clearly illustrate this reciprocity 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. Although those of skill in the art may implement the described functionality in varying ways for each particular application, such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

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 includes 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 code or instructions that are internal to the IC, external to 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.

It should be understood that any particular order or hierarchy of steps in any disclosed process is an example of an exemplary method. It should be understood that the specific order or hierarchy of steps in the processes may be rearranged according to design preferences while remaining within the scope of the present invention. The accompanying method claims present elements of the various steps in a sample order, and are not intended to be limited to the specific order or hierarchy presented.

The functions described may be implemented as 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 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. Further, 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. In general, it should be understood that the computer-readable medium may be implemented in any suitable computer program product.

The previous description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present invention. 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 invention. Thus, the present invention 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.

Claims

1. A method of communication, comprising:

identifying a plurality of candidate target access points for handover operations of the access terminal;

sending a message to each of the candidate target access points requesting each access point to attempt to process a signal from the access terminal;

receiving at least one response to at least one of the messages; and

identifying one of the access points for the handover operation based on the at least one response.

2. The method of claim 1, wherein the identification of the candidate target access points comprises:

receiving an indication that a signal having a defined characteristic is detected by an access terminal; and

access points within a defined geographic area that transmit signals having the defined characteristics are identified.

3. The method of claim 2, wherein the identification of access points within the defined geographic area comprises: identifying neighboring access points of a serving access point of the access terminal.

4. The method of claim 2, wherein the defined characteristic comprises a phase offset.

5. The method of claim 1, wherein the at least one response indicates a signal strength of a signal received from the access terminal at one of the access points.

6. The method of claim 1, wherein the identification of one of the access points comprises:

determining, for each of the candidate target access points, a signal strength of a signal received from the access terminal;

determining which of the candidate target access points is associated with a highest signal strength of the determined signal strengths.

7. The method of claim 1, wherein each message indicates at least one of the group consisting of: the uplink spreading code used by the access terminal, the carrier frequency used by the access terminal, and how to respond to the message.

8. The method of claim 1, wherein the at least one response indicates whether at least one of the candidate target access points decoded a signal from the access terminal.

9. The method of claim 1, wherein each candidate target access point comprises a femto node or a pico node.

10. The method of claim 1, wherein the handover comprises a hand-in from a macro access point to the identified one of the access points.

11. The method of claim 1, wherein:

each candidate target access point is restricted to not provide at least one of the group consisting of: signaling, data access, registration, and service; and

the decision to perform the handover operation is based on whether the access terminal is authorized to access one of the identified access points.

12. The method of claim 11, wherein the access terminal switches to a femto channel used by the identified one of the access points if the access terminal is authorized to access the identified one of the access points.

13. An apparatus for communication, comprising:

means for identifying a plurality of candidate target access points for a handover operation of an access terminal;

means for sending a message to each of the candidate target access points requesting each access point to attempt to process a signal from the access terminal;

means for receiving at least one response to at least one of the messages; and

means for identifying one of the access points for the handover operation based on the at least one response.

14. The apparatus of claim 13, wherein the identification of the candidate target access points comprises:

15. The apparatus of claim 14, wherein the identification of access points within the defined geographic area comprises: identifying neighboring access points of a serving access point of the access terminal.

16. The apparatus of claim 14, wherein the defined characteristic comprises a phase offset.

17. The apparatus of claim 13, wherein the at least one response indicates a signal strength of a signal received from the access terminal at one of the access points.

18. The apparatus of claim 13, wherein the identification of one of the access points comprises:

19. The apparatus of claim 13, wherein each message indicates at least one of the group consisting of: the uplink spreading code used by the access terminal, the carrier frequency used by the access terminal, and how to respond to the message.

20. The apparatus of claim 13, wherein the at least one response indicates whether at least one of the candidate target access points decoded a signal from the access terminal.

21. The apparatus of claim 13, wherein each candidate target access point comprises a femto node or a pico node.

22. The apparatus of claim 13, wherein the handover comprises a hand-in from a macro access point to the identified one of the access points.

23. The apparatus of claim 13, wherein:

24. The apparatus of claim 23, wherein the access terminal is handed off to a femto channel used by the identified one of the access points if the access terminal is authorized to access the identified one of the access points.

25. An apparatus for communication, comprising:

a candidate identifier for identifying a plurality of candidate target access points for handover operation of an access terminal and sending a message to each of the candidate target access points requesting each access point to attempt to process a signal from the access terminal; and

a target identifier for receiving at least one response to at least one of the messages to identify one of the access points for the handover operation based on the at least one response.

26. The apparatus of claim 25, wherein the identification of the candidate target access points comprises:

27. The apparatus of claim 26, wherein the identification of access points within the defined geographic area comprises: identifying neighboring access points of a serving access point of the access terminal.

28. The apparatus of claim 26, wherein the defined characteristic comprises a phase offset.

29. The apparatus of claim 25, wherein the identification of one of the access points comprises:

30. A computer program product, comprising:

a computer-readable medium comprising code for causing a computer to:

receiving at least one response to at least one of the messages; and

31. The computer program product of claim 30, wherein the identification of the candidate target access points comprises:

32. The computer program product of claim 31, wherein the identification of access points within the defined geographic area comprises: identifying neighboring access points of a serving access point of the access terminal.

33. The computer program product of claim 31, wherein the defined characteristic comprises a phase offset.

34. The computer program product of claim 30, wherein the identification of one of the access points comprises:

35. A method of communication, comprising:

receiving, at an access point, a request for the access point to attempt to process a signal transmitted by an access terminal;

processing signals received from the access terminal; and

transmitting a response to the request, wherein the response indicates a signal strength of the received signal.

36. The method of claim 35, wherein:

the processing includes decoding; and

the response also indicates that the access point decoded the received signal.

37. The method of claim 35, wherein the request indicates a carrier frequency used by the access terminal.

38. The method of claim 35, wherein the request indicates how to respond to the request.

39. The method of claim 35, wherein the request indicates an uplink spreading code used by the access terminal.

40. The method of claim 35, further comprising: a handover request is received in response to the response.

41. The method of claim 35, wherein the access point comprises a femto node or a pico node.

42. The method of claim 35, wherein the handover comprises a hand-in from a macro access point to the access point.

43. The method of claim 35, wherein the access point is restricted to not provide at least one other access terminal with at least one of the group consisting of: signaling, data access, registration, and service.

44. An apparatus for communication, comprising:

means for receiving, at an access point, a request for the access point to attempt to process a signal transmitted by an access terminal;

means for processing signals received from the access terminal; and

means for transmitting a response to the request, wherein the response indicates a signal strength of the received signal.

45. The apparatus of claim 44, wherein:

the processing includes decoding; and

the response also indicates that the access point decoded the received signal.

46. The apparatus of claim 44, wherein the request indicates a carrier frequency used by the access terminal.

47. The apparatus of claim 44, wherein the request indicates how to respond to the request.

48. The apparatus of claim 44, wherein the request indicates an uplink spreading code used by the access terminal.

49. The apparatus of claim 44, wherein the means for receiving is configured to receive a handover request in response to the response.

50. The apparatus of claim 44, wherein the access point comprises a femto node or a pico node.

51. The apparatus of claim 44, wherein the handover comprises a hand-in from a macro access point to the access point.

52. The apparatus of claim 44, wherein the access point is restricted to not provide at least one other access terminal with at least one of the group consisting of: signaling, data access, registration, and service.

53. An apparatus for communication, comprising:

an acquisition request processor for receiving, at an access point, a request for the access point to attempt to acquire a signal transmitted by an access terminal;

a signal processor for processing signals received from the access terminal; and

a response generator to transmit a response to the request, wherein the response indicates a signal strength of the received signal.

54. The apparatus of claim 53, wherein:

the processing includes decoding; and

the response also indicates that the access point decoded the received signal.

55. The apparatus of claim 53, wherein the request indicates at least one of the group consisting of: the uplink spreading code used by the access terminal, the carrier frequency used by the access terminal, and how to respond to the request.

56. The apparatus of claim 53, further comprising: a handover controller to receive a handover request in response to the response.

57. A computer program product, comprising:

a computer-readable medium comprising code for causing a computer to:

processing signals received from the access terminal; and

58. The computer-program product of claim 57, wherein:

the processing includes decoding; and

the response also indicates that the access point decoded the received signal.

59. The computer program product of claim 57, wherein the request indicates at least one of the group consisting of: the uplink spreading code used by the access terminal, the carrier frequency used by the access terminal, and how to respond to the request.