KR20140106727A - Identification of target node for wireless handoff - Google Patents

Abstract

The identification of the access point to which the access terminal is to be handed off entails, in some aspects, identifying an access point in the set of access points that can be detected by the access terminal. For example, the access terminal may receive a signal having an identified characteristic (e.g., a particular phase offset) from the access point. Each access point in the set of access points associated with the identified characteristic may be directed to attempt to decode the signal from the access terminal. The access point of the candidate set to be used for the handoff operation can be determined based on the signal received from the access terminal, if any, by each of the candidate access points.

Description

IDENTIFICATION OF TARGET NODE FOR WIRELESS HANDOFF < RTI ID = 0.0 >

This application claims the benefit of priority to U.S. Provisional Application Serial No. 60 / 979,801, filed October 12, 2007, co-owned and assigned to Attorney Docket No. 080054P1, the disclosure of which is incorporated herein by reference .

This application relates generally to wireless communications, and more particularly, to improving communication performance not exclusively.

Wireless communication systems are widely deployed to provide various types of communication (e.g., voice, data, multimedia services, etc.) to multiple users. As the demand for high-speed and multimedia data services increases rapidly, there is a challenge to implement efficient and robust communication systems with improved performance.

In order to complement conventional mobile telephone network bases such as macro base stations, small-coverage base stations may be used (e.g., installed in the user's home) to provide more robust indoor wireless coverage for mobile units. Such small-coverage base stations are generally known as access point base stations, Home Node B, or femtocells. Typically, such small-coverage base stations are connected to the Internet and the mobile operator's network via a DSL router or cable modem.

When the mobile unit moves all over a given geographical area, the mobile unit may need to be handed off from one of the base stations of the wireless communication system to another base station. In such a system, the small-coverage base stations may be deployed in an ad-hoc manner. For example, small-coverage base stations may be deployed based on the individual decisions of the owners installing the base stations. Thus, within a given area, there can be a relatively large number of these small-coverage base stations to which the mobile unit can be handed off. As a result, there is a need for efficient handoff methods in wireless communication systems that use a large number of base stations.

A summary of exemplary aspects of the disclosure is described below. It is to be understood that any reference in the specification to the terms of the disclosure may refer to one or more aspects of the disclosure.

In some aspects, the present disclosure is directed to an access terminal identifying an access point to be handed off. For example, when an access terminal detects a signal from an access point, there may be ambiguity about the identity of the access point. In such a case, identifying the access point to be handed off by the access terminal may involve determining which of the set of access points in the given area transmitted the signal detected by the access terminal.

In some aspects, the present disclosure is directed to identifying a set of candidate access points for a handoff operation. For example, the network node may receive a message from the access terminal indicating that the access terminal has received a signal having an identified characteristic (e.g., a particular phase offset). In such a case, the network node may define a set of candidate access points by determining which access point generates signals with the identified characteristics in the vicinity of the access terminal.

In some aspects, the present disclosure is directed to identifying an access point for a handoff operation based on a signal received at the access point. For example, each access point in a candidate set of access points may be instructed to detect a signal from the access terminal and attempt to transmit, if any, a report to the network node indicating the signal received from the access terminal have. The network node may then determine which of the candidate sets will be used for handoff operation. For example, an access point receiving a signal from the access terminal at the highest signal strength may be selected as the target access point for handoff.

In some aspects, the access points of the candidate set may include femto nodes having coverage areas that are smaller than the coverage area provided by the macro access point. In some aspects, these access points may be deployed ad hoc.

These and other exemplary aspects of the present disclosure will be described in the detailed description, the appended claims below, and the accompanying drawings.
1 is a simplified block diagram of several exemplary aspects of a communication system configured to perform handoff operations in accordance with the teachings herein.
2 is a simplified diagram of a wireless communication system including access points and access terminals.
3 is a simplified diagram of a wireless communication system including femto nodes.
4 is a simplified diagram illustrating exemplary coverage areas for wireless communication.
5A and 5B are flow diagrams illustrating some aspects of exemplary operations that may be performed to perform handoff operations in accordance with the teachings herein.
6 is a simplified block diagram of several exemplary components of nodes configured to perform handoff operations in accordance with the teachings herein.
7 is a simplified block diagram of several exemplary aspects of communication components.
Figures 8 and 9 are simplified block diagrams of several exemplary aspects of devices configured to facilitate communication handoff as described herein.
According to a common implementation, the various features shown in the figures may not be drawn to scale. Thus, the dimensions of the various features may optionally be expanded or reduced for clarity. In addition, some of the figures may be simplified for clarity. Accordingly, the drawings do not depict all components of a given device (or device) or method. Finally, like reference numerals can be used to designate like features throughout the specification and figures.

Various aspects of the present disclosure are described below. It should be apparent that the teachings herein may be implemented in a wide variety of forms and that any particular structure, function, or all of the features disclosed herein is merely exemplary. Based on the teachings herein, one of ordinary skill in the art should understand that the aspects disclosed herein may be implemented independently of any other aspects, and that such 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 number of aspects described herein. Additionally, those devices may be implemented or performed using other structures, functions, or other structures and functions in addition to or in addition to one or more aspects described herein. In addition, aspects may include at least one element of the claim.

1 illustrates several nodes in an exemplary communication system 100 (e.g., a portion of a communication network). For illustrative purposes, various aspects of the present disclosure will be described in the context of one or more network nodes, access points, and access terminals in communication with one another. It should be understood, however, that the teachings herein may be applied to other similar devices or other types of devices that are referenced using other terms.

The access points 102, 104, and 106 in the system 100 may include one or more terminals (e.g., access terminals 108, 104, and 106) that may be installed within the associated geographic area, (E.g., network connectivity). In addition, the access points 102-106 may communicate with one or more network nodes (represented as network nodes 110 for convenience) to facilitate broadband network connectivity. Such network nodes may have various forms, for example, one or more wireless and / or core network entities (e.g., a mobility manager such as a base station controller, a mobility management entity, a wireless network controller, etc.).

When the access terminal 108 is in a connected state (e.g., during an active call), the access terminal 108 may access the access points (e.g., the macro access point 102) ). ≪ / RTI > However, when the access terminal 108 moves closer to the access point 104, the access terminal 108 may receive stronger signals from the access point 104 than the access point 102. Consequently, in order to maintain the best possible radio signal quality for the access terminal 108, the access terminal 108 may receive a signal from the access point 102 (e.g., a source access point) Lt; / RTI > access point).

However, the identification of an access point that actually transmits signals received by the access terminal 108 may not be readily known. For example, in some scenarios, multiple access points in a given area may transmit using similar parameters, where signals (e.g., pilots or beacons) transmitted by these access points are not easily distinguished .

1 illustrates a method for identifying an access point 104 from which an access terminal 108 may be handed off. When the access terminal 108 is in a connected state, it can analyze signals received 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 a pseudorandom number ("PN") sequence. The access terminal 108 may also measure specific characteristics of each signal, e.g., received signal strength. In order to facilitate the handoff by allowing the network node 110 to determine whether the access terminal 108 should be handed off and / or by adjusting the handoff using the source and target access points, Information to the network node (110).

The network node 110 may determine the identity of an access terminal transmitting signals reported by the access terminal 108 in cooperation with one or more access points in the system 100. For example, the access point ("AP") candidate set identifier 112 may identify a set of candidate target access points that may be transmitting these signals. As will be described in more detail below, a macro access point 102 (e. G., A macro as a neighbor) that transmits signals having the same characteristics (e. G., Phase offset) as the signals received by the access terminal 108 The candidate set may be selected by identifying nearby access points (as indicated by neighbor cell information of all femto access points having access point 102). Thus, the candidate set identifier 112 may make this determination based on measurement report information provided by the access terminal 108 and neighbor cell information of the femtocells stored in the system configuration database. Once the candidate set is identified, the candidate set identifier 112 may send a request to the access points to each access point in the candidate set to attempt to obtain an uplink signal from the access terminal 108.

In response to the acquisition request, each access point in the candidate set may acquire and monitor the uplink signal of the access terminal 108 and attempt to report back to the network node 110. For example, upon receipt of an acquisition request, the signal processor 114 of the access point 104 may begin to retrieve the signal 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 may transmit the report back to the network node 110. [ To reduce the complexity of FIG. 1, components 114 and 116 are shown only for access point 104. FIG. However, it should be understood that these or similar components may also be integrated into other access points (e.g., access point 106) within system 100.

The target identifier 118 at the network node 110 processes the responses (e.g., signal strength reports) received from the candidate access points that have reported detection of the uplink signal from the AT 108, And identifies the access point that transmitted the signals reported by the access terminal 108. For example, as will be described in greater detail below, the identified access point may correspond to an access point that has reported the highest received signal quality on the uplink from the access terminal 108. Once such an access point is identified, the network node 110 may perform a handoff of the access terminal 108 from a source access point (e.g., access point 102) to a target access point (e.g., access point 104) It may send appropriate handoff request messages to initiate.

In some aspects, such a handoff scheme as such may be used for macro coverage (e.g., a large area cellular network such as a 3G network, generally referred to as a macro cell network or WAN) and smaller coverage (e.g., Based network environment, generally referred to as a LAN). Here, when an access terminal ("AT") moves through such a network, the access terminal may be served by access points providing macro coverage at certain locations, while at other locations, Lt; RTI ID = 0.0 > a < / RTI > area. In some aspects, smaller coverage nodes may be used to provide increased capacity growth, in-building coverage, and different services (e.g., a more robust user experience). In such a case, a relatively large number of smaller coverage nodes may be present in a given area. As a result, in a system in which there is a limited number of transmission parameter values (e.g., phase offsets) that can be used by these nodes, the likelihood of more than one such node using the same parameter values may increase. In such a case, the teachings herein may be used to distinguish nodes that use the same parameters to identify a target node for a handoff operation.

In the description herein, a node providing coverage over a relatively large area may be referred to as a macro node, while a node providing 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, the picode may provide coverage (e.g., coverage within a commercial building) over an area that is smaller than the macro area and larger than the femto node. In various applications, other terms may be used to refer to macro nodes, femto nodes, or other access point-type nodes. For example, a macro node may consist of or be referred to as an access node, a base station, an access point, an eNodeB, a macrocell, and so on. The femto node may also be referred to as a Home Node B, a Home eNode B, an access point base station, a femtocell, or the like. In some implementations, a node may be associated (e.g., partitioned) with one or more cells or sectors. A cell or a sector associated with a macro cell, a femtocell, or a picocell may be referred to as a macro cell, a femtocell, or a picocell, respectively. A brief example of how femtocells are deployed in a network will be described with reference to Figures 2-4.

FIG. 2 illustrates a wireless communication system 200 that is configured to support multiple users, where the teachings of the present disclosure may be implemented. The system 200 provides communications for a plurality of cells 202, such as macro cells 202A-202G, and each cell is associated with a corresponding access point 204 (e.g., access points 204A-204G) ). ≪ / RTI > As shown in FIG. 2, access terminals 206 (e.g., access terminals 206A-206L) may be distributed over various locations throughout the system over time. Each access terminal 206 may communicate on a forward link ("FL") and / or a reverse link ("RL") at a given moment, for example, depending on whether the access terminal 206 is active and whether it is in soft hand- And may communicate with one or more access points (204). The wireless communication system 200 may provide services over a wide geographic area. For example, the macrocells 202A-202G may cover a few square blocks of neighboring small blocks or rural environments.

3 illustrates an exemplary communication system 300 in which one or more femto nodes are deployed within a network environment. In particular, the system 300 includes a plurality of femto nodes 310 (e.g., femto nodes 310A and 310B) that are installed in a relatively small coverage network environment (e.g., in one or more user residences 330) . Each femto node 310 may be coupled to a broadband network 340 (e.g., the Internet) and a mobile operator core network 350 via a DSL router, cable modem, wireless link, or other connection means .

The owner of the femto node 310 may subscribe to a mobile service, such as a 3G mobile service, for example, provided via the mobile operator core network 350. In addition, the access terminal 320 may operate in both macro environments and in smaller coverage (e.g., residential) network environments. That is, depending on the current location of the access terminal 320, the access terminal 320 may be controlled by the macro cell access point 360 associated with the mobile operator core network 350 or by the femto nodes 310 (e.g., , Or a set of femto nodes 310A and 310B residing within the corresponding user residence 330). For example, when a subscriber is outside his home, the subscriber may be served by a standard macro access point (e.g., access point 360), and when the subscriber is near or inside his home, , Node 310A). Here, the femto node 310 may be backwards compatible with the legacy access terminals 320.

FIG. 4 shows an example of a coverage map 400 in which several tracking areas 402 (or routing areas or location areas) are defined, each of which is comprised of several macro coverage areas (404). Here, areas of coverage associated with the tracking areas 402A, 402B, and 402C are depicted as bold lines, and the macro coverage areas 404 are represented as hexagons. The tracking areas 402 also include femto coverage areas 406. [ In this example, each of the femto coverage areas 406 (e.g., femto coverage areas 406C) is shown within a macro coverage area (e.g., macro coverage area 404B). It should be understood, however, that the femto coverage area 406 may not be completely within the macro coverage area 404. In addition, one or more pico coverage areas (not shown) may 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 as a given tracking area 402 or macro coverage area 404. As a result, when an access terminal detects a signal in such a network, the teachings of the present disclosure can be used to efficiently identify which access point (e.g., which femto node) has transmitted the signal. If such an access point is identified, the access terminal may be handed off to the access point if desired.

Additional details regarding handoff operations that may be performed in accordance with the teachings herein will now be described with reference to the flow charts of FIGS. 5A and 5B. In the example of FIG. 1, these operations are initially served by the macro access point 102 and then handed-over to a femto node (e.g., access point 104). The term "hand-in" refers to handoff from the macrocell to the femtocell. It should be understood that the teachings herein may be applied to other types of handoff operations (e.g., handoff from one femto node to another).

The network including the femto nodes may include one or more network entities that facilitate macro-to-femto interoperability. For example, such an entity may 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 standalone components or may be incorporated into other common network components. For convenience, the discussion that follows will describe such functionality as implemented in the network node 110.

5A and 5B (or any of the other operations discussed and disclosed herein) may be implemented as part of certain components (e.g., system 100 and / or as shown in FIG. 6 (E.g., components of the same system 600). However, it should be understood that these operations may be performed by other types of components and may be performed using different numbers of components. It should also be understood that one or more operations described herein may not be used in a given implementation.

Figure 6 illustrates several exemplary components that may be integrated 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 described for a given one of these nodes may also be integrated into other nodes in the communication system. For example, the access point 106 may include components similar to those described for the access point 104 or the access point 102. For example, It should be appreciated that a node may include one or more given components, e.g., an access point may include multiple receivers to operate on multiple frequencies, and may serve multiple access terminals simultaneously.

The access terminal 108, the access point 102, the network node 110 and the access point 104 are connected to the transceivers 602, 604, 606 and 608, respectively, for communication with each other and with other nodes, ). Each transceiver includes a separate transmitter (transmitters 610, 612, 614, and 616) for transmitting signals (e.g., messages) and an individual receiver (receivers 618, 620, 622, 624).

The nodes of FIG. 6 also include other components that may be used with handoff operations as described herein. For example, the nodes may communicate with individual communication controllers 626 (e. G., ≪ / RTI > as described herein) to manage communications with other nodes (e. G., Send and receive messages / indications) , 628, 630, and 632). The nodes may include separate handoff controllers 634, 636, 638 and 640 for facilitating handoff operations and providing other related functions as described herein. Exemplary operations of the other components of Fig. 6 are described below. For purposes of explanation, it is shown in Fig. 6 that certain nodes have certain functions related to supporting handoff. However, one or more of the described components may be utilized in one of these nodes or some other node.

Referring now to FIG. 5A, as indicated at block 502, the femto nodes in the system transmit pilots (or beacons) so that any nearby access terminals can detect the presence of the femto nodes. As described above, a relatively large number of femto nodes may be deployed within the macro coverage area. As a result, there may be some reuse of communications resources between neighboring femto nodes. For example, a given network may allocate a fixed number of PN phase offsets (e.g., 64). Reuse of the phase offsets can occur if there are more femto nodes than the phase offsets in a given area (e.g., within the coverage of the macro AP). As a result, a plurality of femto nodes may transmit signals having similar characteristics in a given area.

The femto nodes in the network may be configured to operate on a single frequency or on multiple frequencies. For example, in some implementations, all femto nodes (or all restricted femto nodes) within a region may operate on a designated femto channel (or femto channels). Depending on the particular implementation, a single frequency or one or more multiple frequencies may overlap with one or more frequencies used by the macro access point. As a result, the access terminal operating on a given frequency on the macro node can be prepared to ensure that it receives at least some of the beacons transmitted by the femto node. For example, a femto node may use frequency hopping, so that at various times the femto node transmits beacons at each of a defined set of frequencies (corresponding to femtos and macrochannels).

As indicated by block 514, the access terminal 108 (e.g., receiver 618) may periodically monitor the downlink for pilot signals. When in the active call, the access terminal 108 searches and monitors the downlink for pilots almost continuously. Along with this monitoring, the access terminal 108 may identify one or more characteristics associated with any detected signals. For example, based on the neighbor report received from the serving macro access point 102, the access terminal 108 may monitor signals with specific PN sequence phase offsets. When such signals are detected, the access terminal 108 may measure the corresponding received signal strength of these signals.

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

As indicated by block 508, the access terminal 108 (e. G., Measurement report generator 642) may generate a report on the downlink signals received by the access terminal 108, And provide it to the access point 102. The access point 102 may then forward this information to the network (e.g., network node 110). As described above, the measurement report may include information such as received signal strength and phase offset for a given signal. For example, the report may include a received signal strength value (e.g., Ec / Io) for each pilot received by the access terminal 108, PN sequence offsets of all pilots received by the access terminal 108, And the PN sequence offset of the access terminal 108 (e.g., the terminal uses as its timing reference).

As indicated by blocks 510-514, the access point 102 and the network node 110 may selectively monitor signals or other related conditions associated with the access terminal 108 to determine whether handoff is ensured Or determine the optimal timing for handoff. For example, the macro network may monitor channel performance at macro level and / or femto level. In the example of FIG. 6, the condition monitor 644 of the access point 102 may monitor channel performance conditions, such as power levels and / or frame errors, associated with communication with the access terminal 108 . Here, without immediately proceeding with a handoff as a result of the threshold condition satisfied at block 506, the macro network may monitor conditions for a period of time, e.g., to ensure that the handoff trigger is not a transient event. In addition, the macro network may choose not to proceed with 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 the access point 102 and the access terminal 108, the handoff may not be guaranteed. Similarly, if the signal strength of the signals received at the access terminal 108 from the access point 102 is high enough (e.g., greater than the signal strength from the measurement report at block 508), the handoff may not be guaranteed have.

Thus, as indicated at block 514, the macro network (e.g., the access point 102) may continue to monitor the selected conditions until it determines whether a handoff should be performed. In the case of deciding not to proceed with the handoff operation, the access terminal 108 may remain on the macro network.

The network node 110 (e.g., candidate set identifier 646) may analyze the measurement report from the access terminal 108 to determine whether to proceed with the handoff, as indicated at block 516, May identify one or more signal characteristics associated with the signal received by the access terminal 108. In some implementations, the network node 110 may determine based on one or more of these characteristics that the signal has been transmitted by the femto node. For example, a known subset of available PN phase offsets in the macro network may be dedicated for use by the femto nodes.

If it is determined that the access terminal 108 has received a signal from the femto node, the candidate set identifier 646 will identify subsets of the femto nodes in the system that may have transmitted the signal. For example, the network node 110 may maintain or obtain information indicating where the femto nodes are deployed in the network (e.g., neighbor and other configurations of the access points). Therefore, the candidate set identifier 646 may use this information to identify femto nodes that are deployed, for example, near the current serving access point (e.g., access point 102) to the access terminal 108 . In this manner, the network node 110 can identify a subset of the femto nodes that are neighbors of the access terminal 108 and therefore capable of generating signals that can be received by the access terminal 108 have.

In addition, the candidate set identifier 646 may determine which femto nodes may generate signals matched with the signals received by the access terminal 108. For example, the network node 110 may maintain or obtain information indicating the PN phase offset (or some other appropriate parameters) used by each femto node in the network. The candidate set identifier 646 may thus use this information to more accurately identify the femto nodes that generated the signal. As a result of these tests, a set of target femto nodes that are candidates for being the target femto node for the access terminal 108 is defined.

If the above tests indicate that only a single femto node is generating the signal (i. E., The candidate set includes only one femto node), for subsequent handoff operations to this target femto node The operational flow may proceed to block 526. [ Alternatively, if more than one candidate femto node is identified at block 516, the operational flow proceeds to blocks 518-524 to identify a single target femto node.

As indicated at block 518, the network node 110 sends a message to each femto node in the candidate set, where each message is processed (e.g., Acquisition) to the femto node. In some aspects, these requests may have the form of handoff request messages that notify femto nodes of potential emergency handoffs, thereby causing the femto nodes to send handoff messages from the access terminal 108 Lt; RTI ID = 0.0 > uplink < / RTI >

In some aspects, it may include information about channel parameters assigned to a connection of the access terminal 108 to allow the femto nodes to process 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. Additionally, 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.

Also, in some implementations, the request may include information about how the femto node should respond to the request. For example, the femto nodes may be instructed to respond irrespective of whether the femto node has successfully acquired signals from the access terminal 108. In addition, the femto nodes may be instructed to respond using specific information regarding the acquired signals. It should be understood that the manner in which the femto node must respond to the request in other implementations may be preconfigured or controlled in some other way.

As indicated at block 520, upon receipt of a request, each femto node in the candidate set attempts to obtain uplink transmissions from the access terminal 108. For example, the acquisition request processor 648 of the access point 104 may direct the receiver 624 to monitor the signals on the uplink, and the parameters received (e.g., scrambling code, frequency, Etc.) to process any signals received by the receiver 624. For example, the signal processor 650 may attempt to demodulate and decode the received signals. Additionally, if the access point 104 successfully acquires a signal from the access terminal 108, the signal processor 650 may generate information about the obtained signals. For example, in some implementations, an indication of the signal energy received from the access terminal 108 is generated.

Based on the results of the acquisition operations, the acquisition response generator 652 (e.g., corresponding to the report generator 116) may be configured to cause the access point 104 to successfully acquire (e.g., ) To the network node (110). For example, in some implementations, a response is sent only when the access point 104 has successfully obtained a signal from the access terminal 108. [ In other implementations, if the access point does not acquire a signal from the access terminal 108, a negative acknowledgment may be sent. In some implementations, the response may include information about the obtained signals (e.g., received signal strength).

As indicated at block 522, the network node 110 receives one or more reports from one or more of the candidate set femto nodes. In the case where only one response is received, it can be assumed that the femto node that transmitted the response is the only femto node that was able to transmit the signal received by the access terminal 108. In this case, the operational flow may proceed to block 526 for subsequent handoff operations.

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

In some implementations, as shown in blocks 526 and 528, the network (e.g., authentication controller 656) may verify that the access terminal 108 is authorized to access the identified femto node . If the access terminal 108 is not authorized (block 530), the network may stop handing off the access terminal 108, which may result in the access terminal 108 remaining on the macro network. . In some cases, the network may hand off the access terminal 108 to operate at a different frequency, e.g., a macro-dedicated frequency. This may be done, for example, to mitigate potential interference between the unauthorized access terminal 108 and the identified femto node.

The authentication operations of blocks 526 and 528 may be used, for example, when the identified femto node is restricted in some manner. For example, a given femto node may only be configured to provide services specific to particular access terminals. In deployments using so-called limited (or closed) associations, a given access terminal may only exist in a macrocell mobile network and a defined set of femto nodes (e.g., in a corresponding user residence 330 as shown in FIG. 3) (E. G., Femto nodes 310). ≪ / RTI > For example, in FIG. 3, each femto node 310 may include associated access terminals 320 (e.g., access terminal 320A) and optionally guest access terminals 320 (e.g., access terminal 320B) Lt; / RTI > In other words, access to the femto nodes 310 may be restricted and the given access terminal 320 may be served by a set of designated (e.g., assumed) femto node (s) 310, May not be served by non-designated femto nodes 310 (e.g., neighboring femto node 310).

In some aspects, a restricted femto node (also referred to as a Closed Subscriber Group Home Node B) is a node that serves a limited provisioned set of access terminals. Such a set can be extended as needed or temporarily or permanently. In some aspects, a CSG (Closed Subscriber Group) 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, a node may be constrained to not provide at least one of signaling, data access, registration, paging, or service to at least one node.

Thus, there can be various relationships between a given femto node and a given access terminal. For example, from the perspective of an access terminal, an open femto node may refer to a femto node having an open association (e.g., a femto node that is allowed to access any access terminal). A restricted femto node may refer to a femto node that is restricted in some manner (e.g., restricted for association and / or registration). A home femto node may refer to a femto node to which the access terminal is authorized to access and operate (e.g., a permanent access is provided for a defined set of one or more access terminals). A guest femto node may refer to a femto node to which the access terminal is temporarily allowed to access or operate. An alien femto node may refer to a pen node that is not allowed to access and operate by an access terminal, except perhaps for emergency situations (e.g., 911 calls).

From the perspective of a restricted femto node, a home access terminal may refer to an access terminal that is authorized to access a restricted femto node (e.g., the access terminal has permanent access to the femto node). A guest access terminal may refer to an access terminal having a temporary access to the restricted femto node (e.g., limited based on deadlines, usage times, bytes, connection counts, or some other criteria or criteria). An external access terminal may refer to an access terminal that does not have permission to access a restricted femto node, except perhaps in emergency situations, such as, for example, 911 (e.g., access with no femto nodes to register with entitlements or permissions Terminal).

Referring again to FIG. 5B, if the access terminal 108 is authorized to access the identified access point at block 528, the operational flow proceeds to blocks 532 and 534 to proceed with the handoff operation. Herein, the one or more handoff controllers 634, 636, 638, and 640 may communicate the urgent handoff and the identification (and, optionally, the operating frequency) of the target femto node (block 532) (E. G., Send a handoff request to the access point 104), and may cooperate to complete the handoff (block 534). ≪ RTI ID = 0.0 > For example, the network node 110 may send a handoff indication message to the access terminal 108, where the only member of the active pilot set is the target femto node (e.g., a hard handoff on the same frequency). The access terminal 108 and the target femto node initiate demodulation over the link between the nodes and the access terminal 108 and send a handoff complete message to the target femto node.

Thus, efficient techniques for providing handoffs between communication nodes are disclosed. Advantageously, these techniques can be used with legacy terminals that are already in operation because changes in wireless signaling procedures may not be required to implement these techniques. Additionally, such techniques may enable maximum utilization of the femto nodes to which a given terminal is authorized to be used. In addition, when the access terminal is allowed to access the femto node, these techniques enable relatively quick handoff to a frequency different from the frequency used by the femto node.

It is to be understood that the teachings herein may be implemented in various types of communication devices. In some aspects, the techniques described herein may be implemented in wireless devices that can be deployed in a multiple-access communication system capable of simultaneously supporting communication for multiple wireless access terminals. Here, each terminal may communicate with one or more access points via transmissions on the forward or 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-input-single-output system, a multiple-input-multiple-output ("MIMO") system, or some other type of system.

A MIMO system uses multiple (N _T ) transmit antennas and multiple (N _R ) receive antennas for data transmission. A MIMO channel formed by N _T transmit antennas and N _R receive antennas may be decomposed into N _S independent channels, where the independent channel is also referred to as spatial channels, and N _{S <} min {N _T , N _R }. Each of the N _S independent channels corresponds to a dimension. If additional orders generated by the multiple transmit and receive antennas are used, the MIMO system can provide improved performance (e.g., higher throughput and / or greater reliability).

A MIMO system may support time division duplex ("TDD") and frequency division duplex ("FDD"). In TDD systems, the forward and reverse link transmissions are on the same frequency domain, so that the reciprocity principle enables estimation of the forward link channel from the reverse link channel. This allows the access point to extract the transmit beam-forming gain on the forward link when multiple antennas are available at the access point.

The teachings herein may be combined into a node (e.g., a device) that utilizes various components for communication with at least one other node. FIG. 7 illustrates several exemplary components that may be utilized to facilitate communication between nodes. In particular, FIG. 7 illustrates a wireless device 710 (e.g., access point) and a wireless device 750 (e.g., access terminal) of a MIMO system 700. At 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. The TX data processor 714 formats, codes, and interleaves the traffic data for each data stream based on a particular coding scheme selected for the data stream to provide coded data.

The coded data for each data stream may be multiplexed with the pilot data using OFDM techniques. In general, the pilot data is a known data pattern that can be processed in a known manner and used in 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 the particular modulation scheme (e.g., BPSK, QSPK, or M-QAM) selected for that data stream Lt; / RTI > The data rate, coding, and modulation for each data stream may be determined by instructions performed by the processor 730. The data memory 732 may store program code, data, and other information used by the processor 730 or other components of the apparatus 710. [

Thereafter, modulation symbols for all data streams are provided to TX MIMO processor 720, which may further process the modulation symbols (e.g., for OFDM). The TX MIMO processor 720 then provides the N _T modulation symbol streams to the N _T transceivers ("XCVR") 722A through 722T. In some aspects, the TX MIMO processor 720 applies beam-forming weights to the symbols of the data streams and to the antenna over which the symbols are transmitted.

Each transceiver 722 receives and processes each symbol stream to provide one or more analog signals and further conditions (e.g., amplifies, filters, and upconverts) the analog signals to provide modulation suitable for transmission over a MIMO channel Signal. N _T modulation symbols from transceivers 722A through 722T are then transmitted from N _T antennas 724A through 724T, respectively.

At the device 750, the transmitted modulated signals are received by N _R antennas 752A through 752R and the received signal from each antenna 752 is provided to each transceiver ("XCVR") 754A through 754R ). Each transceiver 754 conditions (e.g., filters, amplifies, and downcovers) each received signal, digitizes the conditioned signal to provide samples, and further processes the samples to generate a corresponding " And provides a symbol stream.

Receive ( "RX") data processor 760 is a particular receiver processing technique to N _R transceivers to (754) N _T of "detected" symbol streams to receive N _R received symbols streams, and processing from the basis of the Lt; / RTI > The RX data processor 760 then demodulates, deinterleaves, and decodes each detected symbol stream to recover traffic data for the data stream. The processing by the RX data processor 760 is complementary to the processing performed by the TX MIMO processor 720 and the TX data processor 714 at the device 710.

Processor 770 periodically determines what pre-coding matrix to use (described below). The processor 770 forms a reverse link message including a matrix index portion and a rank value portion. The data memory 722 may store program code, data, and other information used by the processor 770 or other components of the apparatus 750.

The reverse link message may include various types of information regarding the communication link and / or the received data stream. The reverse link message is also processed by a TX data processor 738 that receives traffic data for a number of data streams from a data source 736, modulated by a modulator 780, and transmitted by transceivers 754A- 754R, and is sent back to the device 710. [

At device 710 the modulated signals from device 750 are received by antennas 724 and conditioned by transceivers 722 and demodulated by a demodulator ("DEMOD") 740. [ And processed by an RX data processor 742 to extract the reverse link message transmitted by the device 750. The processor 730 determines which pre-coding matrix to use to determine the beam-forming weights and processes the extracted messages.

FIG. 7 also illustrates communication components that may include one or more components that perform handoff operations as disclosed herein. For example, the handoff control component 790 may communicate with other components of the device 710 to transmit / receive handoff-related signals to / from another device (e.g., the device 750) And / or cooperate with the processor 730. Similarly, the handoff control component 792 may be coupled to other components of the device 750 and / or to the processor 750 to transmit / receive handoff-related signals to / from another device (e.g., the device 710) (770). It should be understood that the functionality of two or more of the described components for each device 710 and 750 may be provided by a single component. For example, a single processing component may provide the functionality of the handoff control component 790 and the processor 730, and a single processing component may provide functionality of the handoff control component 792 and the functionality of the processor 770 Can be provided.

The teachings herein may be combined with various types of communication systems and / or communication components. In some aspects, the teachings herein may be implemented in a multi-access (e. G., Multiple access) system that can support communication with multiple users by sharing available system resources (e.g., by specifying one or more bandwidths, transmit power, coding, interleaving, System. ≪ / RTI > For example, the teachings herein may be applied to any one or a combination of the following techniques: Code Division Multiple Access ("CDMA") systems, Multi-Carrier CDMA ("MCCDMA" WCDMA "), high-speed packet access (" HSPA ", "HSPA +" systems, time division multiple access ("TDMA") systems, frequency division multiple access "SC-FDMA") systems, orthogonal frequency division multiple access ("OFDMA") systems, or other multiple access techniques. A wireless communication system utilizing the teachings herein may be configured to implement one or more standards such as IS-95, cdma2000, IS-856, W-CDMA, TDSCDMA, and other standards. A CDMA network may implement wireless technologies such as Universal Terrestrial Radio Access (UTRA), cdma 2000, or some other technology. UTRA includes W-CDMA and LCR (Low Chip Rate). cdma2000 technology covers IS-2000, IS-95 and IS-856 standards. The TDMA network may implement a radio technology such as Global System for Mobile Communications (GSM). The OFDMA network may implement wireless technologies such as Evolved UTRA (E-UTRA), IEEE 802.11, IEEE 802.16, IEEE 802.20, Flash-OFDMDM, and the like. UTRA, E-UTRA, and GSM are part of the Universal Mobile Telecommunications System (UMTS). The teachings herein may be implemented in 3GPP Long Term Evolution (LTE), Ultra Mobile Broadband (UMB) systems, and other types of systems. LTE is a release of UMTS using E-UTRA. Although the specific aspects of this disclosure are described using 3GPP terminology, the teachings of the present disclosure are not limited to 3GPP (Re199, Re15, Re16, Re17) technology as well as 3GPP2 (IxRTT, IxEV-DO RelO, RevA, RevB) It should be understood that the invention may also be applied to other applications.

The teachings herein may be combined (e.g., implemented in or performed by) various devices (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.

For example, an access terminal may include, be embodied as, or be embodied in a user equipment, subscriber station, subscriber unit, mobile station, mobile, mobile node, remote station, remote terminal, user terminal, user agent, user equipment, It can be known as that. In some implementations, the access terminal may be a cellular telephone, a wireless telephone, a Session Initiation Protocol ("SIP") telephone, a wireless local loop ("WLL ") station, a personal digital assistant , Or some other suitable processing device connected to the wireless modem. Accordingly, one or more aspects disclosed herein may be embodied in any computer-readable medium, such as a telephone (e.g., a cellular phone or smartphone), a computer (e.g., a laptop), a portable communication device, a portable computing device Device, video device, or satellite radio), a global positioning system device, or any other suitable device configured to communicate over a wireless medium.

The access point includes a Node B, 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) Or may be embodied in, or be known as, a service ("TF"), a wireless transceiver, a wireless router, a base service set ("BSS"), have.

In some aspects, a node (e.g., an access point) may include an access node for a communication system. Such an access node provides connectivity to or over a network (e.g., a broadband network such as the Internet or a cellular network) over a wired or wireless communication link to the network. Thus, an access node may allow another node (e.g., an access terminal) to access the network or some other function. In addition, it should be understood that one or both of the nodes may be portable, or in some cases, relatively non-portable.

It should also be appreciated that the wireless node may transmit and / or receive information in a non-wireless manner (e.g., via a wired connection). Thus, the receiver and transmitter as described herein may comprise suitable communication interface components (e.g., electrical or optical interface components) for communicating over a non-wireless medium.

The wireless node may communicate over one or more underlying wireless communication links or otherwise support any suitable wireless communication technology. For example, in some aspects, a wireless node may be associated with a network. In some aspects, the network may include a local area network or a broadband network. A wireless device may support or otherwise utilize one or more of a variety of wireless communication technologies, protocols, or standards as discussed herein (e.g., CDMA, TDMA, OFDM, OFDMA, WiMAX, Wi-Fi, have. Similarly, a wireless node may support or otherwise utilize one or more of a variety of corresponding modulation or multiplexing schemes. Accordingly, the wireless node may communicate and establish over one or more wireless communication links using the above and other wireless communication technologies, including appropriate components (e.g., wireless interfaces). For example, a wireless node may include a wireless transceiver with associated transmitter and receiver components that may include various components (e.g., signal generators, non-signal processors) that facilitate communication over a wireless medium.

The components described herein may be implemented in a variety of ways. Referring to Figures 8 and 9, devices 800 and 900 are represented as a series of interrelated functional blocks. In some aspects, the functionality of such blocks may be implemented as a processing system comprising one or more processor components. In some aspects, the functionality of such blocks 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 blocks may also be implemented in some other manner as described herein.

The devices 800 and 900 may include one or more modules capable of performing one or more of the functions described above in connection with the various figures. For example, the candidate identification means 802 may correspond to a candidate set identifier, e.g., as discussed herein. Transmitting means 804 may correspond to a candidate set identifier, e.g., as discussed herein. Receiving means 806 may correspond to a target identifier, e.g., as discussed herein. The access point identification means 808 may correspond to a target identifier, e.g., as discussed herein. Receiving means 902 may correspond to, for example, a communication controller as discussed herein. The processing means 904 may correspond to, for example, a signal processor as discussed herein. Transmitting means 906 may correspond to a communication controller as discussed herein, for example.

It should be understood that any reference to an element herein, using assignments such as "first", "second", etc., generally does not limit the number or order of these elements. Rather, such assignments may be used herein as a convenient way to distinguish between two or more elements or examples of elements. Thus, references to the first and second elements do not mean that only two elements can be used there or that the first element must precede the second element in some way. Also, unless stated otherwise, a set of elements may include one or more elements. In addition, the term "at least one of the forms A, B, or C" as used in the detailed description or the claims means "A or B or C, or any combination of these elements."

Those skilled in the art will appreciate 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 include voltages, currents, electromagnetic waves, magnetic fields or particles, Particles or particles, and any combination thereof.

Those skilled in the art will 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., digital, (Which may be designed using a combination of the two, source coding, or some other technique), various types of programs or design codes incorporating instructions (referred to herein for convenience as "software" or "software modules" ), Or a combination of the two. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps are generally described for 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.

The various illustrative logical blocks, modules, and circuits described in connection with the aspects disclosed herein may be implemented by or implemented within an integrated circuit ("IC"), an access terminal, or an access point have. The IC may be implemented as 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, and executes instructions or codes that reside within the IC, outside the IC, or both can do. A general purpose processor may be a microprocessor, but, in the alternative, the processor may be a 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, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

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

The functions presented herein may be implemented in hardware, software, firmware, or a combination thereof. When implemented in software, the functions may be stored on or transmitted via one or more instructions or code on a computer readable medium. Computer-readable media includes computer storage media and communication media including any medium for facilitating transfer of a computer program from one place to another. The storage medium may be any suitable medium that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise any form of computer readable medium, such as RAM, ROM, EEPROM, CD-ROM or other optical disk storage media, magnetic disk storage media or other magnetic storage devices, And may include, but is not limited to, a general purpose computer, a special purpose computer, a general purpose processor, or any other medium that can be accessed by a particular processor. Also, any connection is properly named as a computer-readable medium. For example, if the software is transmitted from a web site, server, or other remote source via wireless technologies such as coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or infrared radio, and microwave, Wireless technologies such as fiber optic cable, twisted pair, DSL, or infrared radio, and microwave may be included within the definition of such medium. As used herein, a disc and a disc are referred to as compact discs (CD), laser discs, optical discs, DVDs, floppy discs, and Blu- In which a disc magnetically reproduces data, while a disc reproduces data optically through a laser. The combinations may also be included within the scope of computer readable media. In summary, it should be appreciated that a computer-readable medium may be implemented in any suitable computer-program article.

The description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features presented herein.

Claims (1)

Identifying a plurality of candidate target access points for a handoff operation to an access terminal;
Sending a message to each of the candidate target access points to request each access point to attempt to process the signal from the access terminal;
Receiving at least one response to at least one of the messages; And
And identifying one of the access points for the handoff operation based on the at least one response.
Communication method.

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