HK1157110A - Transmit power selection for user equipment communicating with femto cells - Google Patents

Description

Transmit power selection for user equipment communicating with femto cells

Claiming priority based on 35U.S.C. § 119

The present invention claims priority from U.S. provisional patent application No.61/052,930, attorney docket No.081592P1, filed on 13/5/2008, and incorporated herein by reference.

Technical Field

The present invention relates generally to wireless communications, and more particularly, but not exclusively, 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 rapid increase in demand for high-speed and multimedia data services, challenges are presented to implementing efficient and robust communication systems with enhanced performance.

To supplement base stations of conventional mobile telephone networks (e.g., macrocellular networks), small-coverage base stations may be deployed, for example, in a user's home. Such small-coverage base stations are commonly referred to as access point base stations, home nodebs, or femtocells, and may be used to provide more robust indoor wireless coverage to mobile units. Typically, such small coverage base stations are connected to the internet and mobile operator networks via Digital Subscriber Line (DSL) routers or cable modems.

In a typical macro cellular deployment, RF coverage is planned and managed by the cellular network operator to optimize coverage between macro base stations. On the other hand, a user may personally install and deploy a femto base station in an ad hoc fashion. Thus, the femto cell may cause interference on both Uplink (UL) and Downlink (DL) of the macro cell. For example, a femto base station installed near a residential window may cause significant downlink interference to any access terminal outside the premises not served by the femto cell. Furthermore, on the uplink, home access terminals served by femto cells may cause interference on macro cell base stations (e.g., macro node bs).

Femto cells may also interfere with each other and with macro cells due to unplanned deployments. For example, in a multi-dwelling apartment, a femto base station installed near a wall separating two dwellings may cause significant interference to femto base stations in adjacent dwellings. Here, the strongest femto base station (e.g., strongest RF signal strength received at the access terminal) as viewed from the home access terminal is not necessarily the serving base station for that access terminal due to the restricted association policy imposed by the femto base station.

Thus, interference problems may arise in communication systems where the Radio Frequency (RF) coverage of a femto base station is not optimized by a mobile operator and the base station is an ad hoc deployment. Therefore, there is a need for improved interference management for wireless networks.

Drawings

Fig. 1 is a simplified diagram of exemplary aspects of a communication system including a macro coverage area and a smaller scale coverage area;

FIG. 2 is another representation of a wireless communication system for supporting multiple users in which various disclosed embodiments and aspects may be implemented;

fig. 3 is a simplified diagram illustrating the coverage of wireless communications;

fig. 4 is a simplified diagram of exemplary aspects of a communication system including neighboring femtocells;

fig. 5 is a simplified diagram of a wireless communication system including a femto node;

FIG. 6 depicts a number of exemplary components that may be used to facilitate communications between nodes;

fig. 7 is a simplified block diagram of exemplary aspects of a femto node for supporting transmit power selection among user equipment in communication therewith;

fig. 8 is a simplified flow diagram of a process for setting transmit power of a user equipment in communication with a femto node;

fig. 9 is a more detailed flow diagram of a process for setting the transmit power of a user equipment in communication with a femto node by monitoring a busy indicator from a macro cell;

fig. 10 is a more detailed flow diagram of a process for setting the transmit power of user equipment communicating with a femto node by monitoring the received signal power from a macro cell;

fig. 11 is a simplified block diagram of various exemplary aspects of an apparatus for setting transmit power of a user equipment in communication with a femto node.

In accordance with common practice, the various features shown in the drawings may not be drawn to scale. Accordingly, the dimensions of the various features may be arbitrarily expanded or reduced for clarity. In addition, some of the figures may be simplified for clarity. Accordingly, the drawings may not depict all of the components of a given apparatus (e.g., device) or method. In addition, like reference numerals refer to like features throughout the specification and drawings.

Detailed Description

The word "exemplary" is used herein to mean "serving as an example, instance, or illustration. Any "exemplary" embodiment described herein is not to be construed as preferred or advantageous over other embodiments.

The detailed description set forth below in connection with the appended drawings is intended as a description of exemplary embodiments of the present invention and is not intended to represent the only embodiments in which the present invention can be practiced. The term "exemplary" as used herein means "serving as an example, instance, or illustration" and should not be construed as preferred or advantageous over other embodiments. The detailed description includes specific details provided for a thorough understanding of exemplary embodiments of the invention. It will be apparent to one of ordinary skill in the art that the exemplary embodiments of the present invention may be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form in order to better understand the novelty of the exemplary embodiments described herein.

Various embodiments of the invention are described below. It should be recognized that the present disclosure may be embodied in a wide variety of forms and that any specific structure and/or function disclosed herein is merely representative. Based on the disclosure herein, one of ordinary skill in the art should recognize that an embodiment disclosed herein can be implemented independently of any other embodiments and that two or more of these embodiments can be combined in any manner. For example, an apparatus may be implemented or a method may be practiced using any number of the embodiments described herein. In addition, the apparatus may be implemented or the method may be practiced using other structure, functionality, or structure and functionality in addition to or other than one or more of the embodiments described herein.

The disclosure herein may be combined with various types of communication systems and/or system components. In some aspects, the disclosure herein may be applied in a multiple-access system capable of supporting communication for multiple users by sharing available system resources (e.g., by specifying one or more of bandwidth, transmit power, coding, interleaving, and so forth). For example, the disclosure herein may be applied to any one or any combination of techniques: code Division Multiple Access (CDMA) systems, multi-carrier CDMA (MCCDMA), wideband CDMA (W-CDMA), high speed packet access (HSPA, HSPA +) systems, High Speed Downlink Packet Access (HSDPA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, Orthogonal Frequency Division Multiple Access (OFDMA) systems, single carrier FDMA (SC-FDMA) systems, or other multiple access techniques. A wireless communication system employing the disclosure herein may be designed to implement one or more standards, such as IS-95, CDMA2000, IS-856, W-CDMA, TDSCDMA, and others. A CDMA network may implement a radio technology such as Universal Terrestrial Radio Access (UTRA), CDMA2000, and so on. UTRA includes WCDMA and Low Chip Rate (LCR). cdma2000 technologies include IS-2000, IS-95, and IS-856 standards. TDMA networks may implement radio technologies such as global system for mobile communications (GSM). OFDMA networks may implement methods such as evolved UTRA (E-UTRA), IEEE 802.11, IEEE 802.16, IEEE 802.20, and,And so on. UTRA, E-UTRA and GSM are part of the Universal Mobile Telecommunications System (UMTS). The disclosure 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 is used to describe particular embodiments of the present application, it is understood that the disclosure herein may be applied to 3GPP (Re199, Re15, Re16, Re17) technologies as well as 3GPP2(IxRTT, 1xEV-DO, RelO, RevA, RevB) technologies and other technologies.

Fig. 1 illustrates a network system 100 that includes a macro-scale coverage area (e.g., a large-scale cellular network such as a 3G network, which is commonly referred to as a macrocell network) and a smaller-scale coverage area (e.g., a residential-based or building-based network environment). As a node, such as access terminal 102A, moves through the network, a macro access node 104 (also referred to herein as a macro node) serves access terminal 102A at a particular location, where macro access node 104 provides a macro coverage area represented by coverage area 106, while a small scale access node 108 (also referred to herein as a small scale node) serves access terminal 102A at other locations, where small scale access node 108 provides a smaller scale coverage area represented by small scale coverage area 110. In some aspects, the small scale access nodes 108 may be used to provide increased capacity growth, in-building coverage, and different services (e.g., for a more robust user experience).

In the detailed discussion that follows, the macro access node 104 is limited in that it may only provide certain services to certain nodes (e.g., a visitor (visitor) access terminal 102B). Thus, a coverage hole (coverage hole) is caused within the macro coverage area 106.

The size of the coverage hole depends on whether the macro access node 104 and the small scale node 108 operate on the same frequency carrier. For example, when nodes 104 and 108 are on the same channel (e.g., using the same frequency carrier), the coverage hole may correspond closely to the small-scale coverage area 110. In this case, therefore, the access terminal 102A may lose macro coverage (e.g., as indicated by the phantom of the access point 102B) when the access terminal 102A is located in the small-scale coverage area 110.

The small scale node 108 may be, for example, a femto node or a pico node. A femto node may be an access node with a limited coverage area, such as a home or apartment. A node that provides coverage over an area that is smaller than a macro area and larger than a femto area may be referred to as a pico node (e.g., providing coverage within a commercial building). It should be understood that the disclosure herein may be implemented with various types of nodes and systems. For example, a pico node or some other type of node may provide the same or similar functionality as a femto node for a different (e.g., larger) coverage area. Thus, similar to femto nodes, pico nodes are limited, which may be associated with one or more home access terminals, and so on, as will be discussed more fully below.

When the nodes 104 and 108 are on adjacent channels (e.g., using different frequency carriers), a smaller coverage hole 112 may be created in the macro coverage area 104 due to adjacent channel interference from the small scale node 108. Thus, when the access terminal 102A is operating on a neighboring channel, the access terminal 102A may receive macro coverage at a location closer to the small-scale node 108 (e.g., just outside of the smaller coverage hole 112).

The co-channel coverage hole may be relatively large, depending on system design parameters. For example, assuming free-space propagation loss and, at worst, no wall separation between the small-scale node 108 and the access terminal 102B, if the interference of the small-scale node 108 is at least as low as the thermal noise floor (floor), the coverage hole will have a radius of about 40 meters for a CDMA system where the transmit power of the small-scale node 108 is 0 dBm.

Thus, there is a tradeoff between minimizing failures in the macro coverage area 106 while maintaining adequate coverage within a specified smaller scale environment (e.g., femto node 108 coverage in a home). For example, when a restricted femto node 108 is at the edge of a macro coverage area 106, a visitor access terminal may lose macro coverage and a call may drop as the visitor access terminal approaches the femto node 108. In this case, one solution for the macro cellular network is to move the visitor access terminal to another carrier (e.g., when the adjacent channel interference from the femto node is small). However, the use of separate carrier frequencies is not always feasible due to the limited spectrum available to each operator. In any case, another operator may be using the carrier used by femto node 108. As a result, a visitor access terminal associated with another operator may encounter a coverage hole on the carrier caused by the restricted femto node 108.

Fig. 2 illustrates another representation of a wireless communication system 100 for supporting a large number of users in which various embodiments and aspects disclosed herein may be implemented. As shown in fig. 1B, for example, the wireless communication system 100 provides communication for a plurality of cells 120 (e.g., macro cells 102A-102G), each of which is served by a corresponding Access Point (AP)104 (e.g., APs 104A-104G). Each cell may also be divided into one or more sectors. Various Access Terminals (ATs) 102 (e.g., ATs 102A-102K), also interchangeably referred to as User Equipment (UE), are dispersed throughout the system. Each AT 102 may communicate with one or more APs 104 on a Forward Link (FL) and/or a Reverse Link (RL) AT a given moment, depending on, for example, whether the AT is active and whether it is in soft handoff. The wireless communication system 100 may provide service over a large geographic area, for example, the macro cells 102A-102G may cover some adjacent neighborhoods.

Other terminology may be used to refer to macro nodes 104, femto nodes 108, or pico nodes in various applications. For example, the macro node 104 may be configured or referred to as an access node, base station, access point, enodeb, macro cell, Macro Node B (MNB), and so on. Also, femto node 108 may be configured or referred to as a Home Nodeb (HNB), home enodeb, access point base station, femto cell, and so forth. Cells associated with a macro, femto, or pico node may be referred to as a macro, femto, or pico cell, respectively.

As previously described, femto node 108 may be restricted in certain aspects. For example, a given femto node 108 may only provide service to a limited set of access terminals 106. Thus, in deployments with so-called restricted (or closed) associations, a given access terminal 106 may be served by a macro cell mobile network and a limited set of femto nodes 108 (e.g., femto nodes within a corresponding user residence).

A restricted, defined set of access terminals 106 (also referred to as a closed subscriber group home node B) associated with a restricted femto node 108 may be temporarily or permanently extended when necessary. In some aspects, a Closed Subscriber Group (CSG) may be defined as a set of access nodes (e.g., femto nodes) that share a common access control list of access terminals. In some implementations, all femto nodes (or, all restricted femto nodes) in an area can operate on designated channels referred to as femto channels.

Various relationships may be defined between restricted femto nodes and a given access terminal. For example, an open femto node may refer to a femto node with unrestricted association from the perspective of an access terminal. A restricted femto node refers to a femto node that is restricted in some respect (e.g., association and/or registration restricted). A home femto node refers to a femto node that an access terminal is authorized to access and operate. A guest femto node refers to a femto node to which an access terminal is temporarily authorized to access or operate. An alien femto node refers to a femto node where an access terminal is not authorized to access or operate except for possible emergency situations (e.g., 911 calls).

From the perspective of the restricted femto node, a home access terminal (or home user equipment "HUE") refers to an access terminal that is authorized to access the restricted femto node. A guest access terminal refers to an access terminal that is capable of temporarily accessing a restricted femto node. An alien access terminal refers to an access terminal that is not allowed access to a restricted femto node except for possible emergency situations (e.g., 911 calls). Thus, in some aspects, an alien access terminal may be defined as an access terminal that is ineligible or not allowed to register with a restricted femto node. Access terminals that are currently restricted (e.g., denied access) by restricted femto nodes are referred to herein as visitor access terminals. Thus, a visitor access terminal may correspond to a foreign access terminal and to a guest access terminal when service is not allowed.

Fig. 3 shows an example of an overlay 300 of a network in which a plurality of tracking areas 302 (or routing areas or positioning areas) are defined. In particular, the thick lines of fig. 3 depict the coverage areas associated with tracking areas 302A, 302B, and 302C.

The system provides wireless communication via a plurality of cells 304 (represented by hexagons, e.g., macro cells 304A and 304B), each of which is served by a corresponding access node 306 (e.g., access nodes 306A-306C). As shown in fig. 3, at a given point in time, access terminals 308 (e.g., access terminals 308A and 308B) can be dispersed at various locations in the network. For example, each access terminal 308 can communicate with one or more access nodes 306 on a Forward Link (FL) and/or a Reverse Link (RL) at a given moment, depending on whether the access terminal 308 is active and whether it is in soft handoff.

The tracking area 302 also includes a femto coverage area 310. In this example, each femto coverage area 310 (e.g., femto coverage areas 310A-310C) is depicted as being within a macro coverage area 304 (e.g., macro coverage area 304B). However, it should be understood that the femto coverage area 310 may not be entirely within the macro coverage area 304. In practice, a large number of femto coverage areas 310 may be defined with a given tracking area 302 or macro coverage area 304. Likewise, one or more pico coverage areas (not shown) may be defined within a given tracking area 302 or macro coverage area 304. To reduce the complexity of fig. 3, only some of the access nodes 306, access terminals 308, and femto nodes 710 are shown.

Fig. 4 illustrates a network 400 in which a femto node 402 is deployed in an apartment building. Specifically, in this example, femto node 402A is deployed in apartment 1 and femto node 402B is deployed in apartment 2. The femto node 402A is a home femto node for the access terminal 404A. The femto node 402B is a home femto node for the access terminal 404B.

As shown in fig. 4, for the case where femto nodes 402A and 402B are restricted, each access terminal 404 (e.g., 404A and 404B) may only be served by the femto node 402 associated (e.g., home). However, in some cases, limited association may lead to negative geometry and disruption of femto nodes. For example, in fig. 4, the femto node 402A is closer to the access terminal 404B than the femto node 402B, and thus may provide a stronger signal at the access terminal 404B. Thus, the femto node 402A may unduly interfere with reception at the access terminal 404B. This situation can therefore affect the coverage radius around the femto node 402B where the associated access terminal 404 can initially acquire the system and remain connected to the system.

Fig. 5 illustrates an exemplary communication system 500 in which one or more femto nodes are deployed in a network environment. In the communication system 500, connections of a femto node environment may be established in various ways. In particular, system 500 includes a plurality of femto nodes 510 (e.g., femto nodes 510A and 510B) installed in a relatively small scale network environment (e.g., in one or more user residences 530). Each femto node 510 may be coupled to a wide area network 540 (e.g., the internet) and a mobile operator core network 550 via a DSL router, cable modem, wireless link, or other connectivity means (not shown). As described herein, each femto node 510 can be utilized to provide service to an associated access terminal 520 (e.g., access terminal 520A) and, optionally, to other access terminals 520 (e.g., access terminal 520B). In other words, access to femto nodes 510 may be restricted such that a given access terminal 520 may be served by a set of designated (e.g., home) femto nodes 510 and not be served by any non-designated femto nodes 510 (e.g., neighbor's femto nodes 510). Access terminal 520 may also be referred to herein as user equipment 520 (UE). Femto node 510 may also be referred to herein as a Home Node B (HNB).

The owner of the femto node 510 may subscribe to mobile services, for example, 3G mobile services provided through the mobile operator core network 550. In addition, the access terminal 520 may be capable of operating in both macro environments and smaller scale (e.g., residential) environments. In other words, depending on the current location of the access terminal 520, the access terminal 520 may be served by an access node 560 of the macro cell mobile network 550 or by any one of a set of femto nodes 510 (e.g., femto nodes 510A and 510B located within a corresponding user residence 530). For example, a subscriber may be served by a standard macro access node (e.g., node 560) when he is outside his home, and by a femto node (e.g., node 510A) when he is at home. Here, it should be appreciated that femto node 510 may be backward compatible with existing access terminals 520.

In the embodiments described herein, the owner of the femto node 510 subscribes to mobile services, e.g., 3G mobile services provided through the mobile operator core network 550, and the UE520 is capable of operating in both macro cellular environments and smaller scale residential network environments.

A home femto node is a base station on which an AT or UE is authorized to operate. A visitor femto node refers to a base station on which an AT or UE may be temporarily authorized to operate, and a foreign femto node is a base station on which an AT or UE is not authorized to operate.

Femto node 510 may be deployed on a single frequency or, alternatively, on multiple frequencies. Depending on the particular configuration, the single frequency and one or more of the multiple frequencies may overlap with one or more frequencies used by the macro node (e.g., node 560).

An access terminal 520 may be configured to communicate with one of a macro network 550 or a femto node 510 but not both at the same time. Additionally, an access terminal 520 served by a femto node 510 may not be in a soft handoff state with the macro network 550.

In some aspects, the access terminal 520 may be configured to connect to a preferred femto node (e.g., a home femto node for the access terminal 520) as long as the connection is feasible. For example, it may be desirable for the access terminal 520 to communicate only with the home femto node 510 as long as the access terminal 520 is in the user's home 530.

In some aspects, if the access terminal 520 is operating within the macro cellular network 550, but is not on its most preferred network (e.g., as defined by the preferred roaming list), the access terminal 520 may continue to search for the most preferred network (e.g., the preferred femto node 510) using preferred system reselection (BSR), which may include periodically scanning for available systems to determine if a preferred system is currently available, and then attempting to associate with the preferred system. With acquisition entry (acquisition entry), the access terminal 520 may be limited to searching for specific frequency bands and channels. For example, the search for the most preferred system may be repeated periodically. Upon discovering the preferred femto node 510, the access terminal 520 may select the preferred femto node 510 to camp within its coverage area.

The disclosure herein may be applied to a wireless multiple-access communication system that simultaneously supports communication with multiple wireless access terminals. As described above, each terminal may communicate with one or more base stations via transmissions on the forward and reverse links. The forward link (or downlink) refers to the communication link from the base stations to the terminals, and the reverse link (or uplink) refers to the communication link from the terminals to the base stations. The communication link may be established via a single-input single-output system, a multiple-input multiple-output (MIMO) system, or some other type of system.

A MIMO system employs multiple (NT) transmit antennas and multiple (NR) receive antennas for data transmission. The MIMO channel formed by the NT transmit antennas and NR receive antennas can be decomposed into multiple (NS) independent channels, also referred to as spatial channels, where NS ≦ min { NT, NR }. Each of the NS independent channels corresponds to a dimension. MIMO systems may provide improved performance (e.g., higher throughput and/or greater reliability) if the additional dimensionalities created by the multiple transmit and receive antennas are utilized.

MIMO systems may support Time Division Duplexing (TDD) and Frequency Division Duplexing (FDD). In a TDD system, the forward and reverse link transmissions are on the same frequency domain, so that the forward link channel can be estimated from the reverse link channel according to reciprocity principles. This enables the access point to extract transmit beamforming gain on the forward link when multiple antennas are available at the access point. The disclosure herein may be incorporated into a node (e.g., a device) that uses various components to communicate with at least one other node.

FIG. 6 depicts a number of example components that may be employed to facilitate communications between nodes. In particular, fig. 6 illustrates a wireless device 1510 (e.g., an access point) and a wireless device 1550 (e.g., an access terminal) of a MIMO system. At access point 1510, traffic data for a number of data streams is provided from a data source 1512 to Transmit (TX) data processor 1514.

In some aspects, each data stream is transmitted over a respective transmit antenna. TX data processor 1514 formats, codes, and interleaves the traffic data for each data stream based on a particular coding scheme selected for that data stream to provide coded data.

The coded data for each data stream can be multiplexed with pilot data using Orthogonal Frequency Division Multiplexing (OFDM) techniques. The pilot data is typically a known data pattern that is processed in a known manner and may be used at the receiver system to estimate the channel response. The multiplexed pilot and coded data for each data stream is then modulated (i.e., symbol mapped) based on a particular modulation scheme selected for that data stream to provide modulation symbols. As a non-limiting example, some suitable modulation schemes are: binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK), multi-level phase shift keying (M-PSK), and multi-level quadrature amplitude modulation (M-QAM).

The data rate, coding, and modulation for each data stream can be determined by instructions performed by processor 1530. A data memory 1532 may store program codes and other information used by the processor 1530 or other components of the access point 1510.

The modulation symbols for all data streams are then provided to a TX MIMO processor 1520, which may further process the modulation symbols (e.g., for OFDM). The TX MIMO processor 1520 then provides NT modulation symbol streams to NT transceivers (XCVR)1522 (e.g., 1522A through 1522T). In some aspects, the TX MIMO processor 1520 applies beamforming weights to the symbols of the data streams and to the antenna from which the symbol is being transmitted.

Each transceiver 1522 receives and processes a respective symbol stream to provide one or more analog signals, and further conditions (e.g., amplifies, filters, and upconverts) the analog signals to provide a modulated signal suitable for transmission over the MIMO channel. NT modulated signals from transceivers 1522A through 1522T are then transmitted from corresponding NT antennas 1524 (e.g., 1524A through 1524T).

At access terminal 1550, the transmitted modulated signals can be received by NR antennas 1552 (e.g., 1552A through 1552R) and the received signal from each antenna 1552 can be provided to a respective transceiver 1554 (e.g., 1554A through 1554R). Each transceiver 1554 may condition (e.g., filter, amplify, and downconvert) a respective received signal, digitize the conditioned signal to provide samples, and further process the samples to provide a corresponding "received" symbol stream.

A Receive (RX) data processor 1560 then receives and processes the NR received symbol streams from NR transceivers 1554 based on a particular receiver processing technique to provide NT "detected" symbol streams. The RX data processor 1560 then demodulates, deinterleaves, and decodes each detected symbol stream to recover the traffic data for the data stream. Thus, the processing by RX data processor 1560 is complementary to that performed by TX MIMO processor 1520 and TX data processor 1514 at access point 1510.

A processor 1570 periodically determines which pre-coding matrix to use (as described below). Processor 1570 formulates a reverse link message comprising a matrix index portion and a rank value portion. A data memory 1572 may store program codes, data, and other information used by processor 1570 or other components of access terminal 1550.

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 1538, modulated by a modulator 1580, conditioned by transceivers 1554A through 1554R, and transmitted via respective antennas 1522A through 1552R back to access point 1510, where TX data processor 1538 also receives traffic data for a number of data streams from a data source 1536.

At the access point 1510, the modulated signals from the access terminal 1550 are received by the antennas 1524, conditioned by the transceivers 1522, demodulated by a demodulator (DEMOD)1540, and processed by a RX data processor 1542 to extract the reverse link message transmitted by the access terminal 1550. The processor 1530 then determines which coding matrix to use for determining the beamforming weights then processes the extracted message.

Fig. 6 also illustrates communication components that may include one or more components for performing the transmit power control operations described herein. For example, as disclosed herein, a code control component 1590 may cooperate with the processor 1530 and/or other components of the access point 1510 to send signals to another device (e.g., access terminal 1550) and/or receive signals from another device (e.g., access terminal 1550). Similarly, the code control component 1592 may cooperate with the processor 1570 and/or other components of the access terminal 1550 to send and/or receive signals to/from another device (e.g., the access point 1510). It should be appreciated that for each wireless device 1510 and 1550, the functionality of two or more of the described components can be provided by a single component. For example, a single processing component may provide the functionality of the code control component 1590 and the processor 1530 and a single processing component may provide the functionality of the code control component 1592 and the processor 1570.

An access terminal as described herein can be called a mobile station, user equipment, subscriber unit, subscriber station, remote terminal, user agent, or user device. In some implementations, the node may include, be implemented in, or consist of: 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.

Thus, one or more aspects disclosed herein may comprise, be implemented in, or be comprised of various types of apparatus. The apparatus may include a telephone (e.g., a cellular telephone or smart phone), a computer (e.g., a laptop), a portable communication device, a portable computing device (e.g., a personal data assistant), an entertainment device (e.g., a music or video device or a satellite radio), a global positioning system device, or any other suitable device configured to communicate via a wireless medium.

As described above, in some aspects, a wireless node may comprise an access node (e.g., an access point) for a communication system. The access node may provide a connection to, or for, a network (e.g., a wide area network such as the internet or a cellular network), for example, via a wired or wireless communication link. Thus, an access node may enable another node (e.g., an access terminal) to access a network or implement some other functional element. Additionally, it is to be appreciated that one or both of the nodes may be portable or, in some cases, relatively non-portable. Further, it is to be appreciated that a wireless node (e.g., a wireless device) can also be capable of transmitting and/or receiving information in a non-wireless manner via a suitable communication interface (e.g., via a wired connection).

The wireless nodes may communicate via one or more wireless communication links that are based on or 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 comprise a local area network or a wide area network. The wireless device may support or use one or more of various wireless communication technologies, protocols, or standards (e.g., CDMA, TDMA, OFDM, OFDMA, WiMAX, Wi-Fi, etc.) as described herein. Similarly, the wireless node may support or use one or more of various corresponding modulation or multiplexing schemes. The wireless node thus includes suitable components (e.g., air interfaces) for establishing or communicating via one or more wireless communication links using the above-described or other wireless communication techniques. For example, a wireless node may include wireless transceivers associated with transmitter and receiver components, which may include various components (e.g., signal generators and signal processors) for facilitating communication over a wireless medium.

Fig. 7 illustrates various components of an access node 700 (also referred to herein as a femto node 700) that may be used in one or more implementations illustrated herein. However, it is to be appreciated that in some implementations the femto node 700 may not include all of the components depicted in fig. 7, while in other implementations the femto node 700 may utilize most or all of the components depicted in fig. 7.

Briefly, a femto node 700 includes a transceiver 710 for communicating with other nodes (e.g., access terminals). The transceiver 710 includes a transmitter 712 for transmitting signals and a receiver 714 for receiving signals.

The femto node 700 may also include a transmit power controller 740 for determining the transmit power of the transmitter 712 and user equipment 520 (fig. 5) in communication with the femto node 700. The femto node 700 includes a communication controller 782 for managing communications with other nodes and for providing other related functionality illustrated herein. The femto node 700 may also include an authorization controller 784 for managing access to other nodes and for providing other related functionality as illustrated herein. The node detector 786 may determine whether a node of a particular type is in a given coverage area.

The transmit power controller 740 may include an interference monitor 744 for monitoring interference on the macro cell caused by the user equipment 520 communicating with the femto node 700. The interference may be based on the total received signal strength and the received pilot strength. The transmit power controller 740 may also include a signal-to-noise ratio (SNR) determiner 742 for determining an SNR value associated with the femto node 700.

The signal strength determiner 720 may determine a total received signal strength value (e.g., received signal strength indication, RSSI). The received pilot strength determiner 730 may determine a signal strength value associated with the pilot signal. The path/coupling loss determiner 760 may determine the coupling loss between the HUE and the macrocell in various ways, as described in detail below.

As described in detail below, the transmit power determiner 750 determines an acceptable transmit power to use when the HUE is communicating with the femto node 700 in order not to generate undue interference on the macro cell.

As described in detail below, busy indication determiner 770 may monitor broadcasts from the macro cell that include a busy indicator 772, which may indicate the amount of traffic and interference on the macro cell. The busy indicator determiner 770 may also generate a femto busy indicator 774 for transmission to the HUE520 in order to adjust the transmit power of the HUE 520.

The memory 790 may store a number of useful parameters associated with the operation of some of the functional elements. As a non-limiting example, memory 790 may include a pilot/total signal strength relationship 732 corresponding to a known or estimated relationship between pilot strength and total strength as determined by signal strength determiner 720 and received pilot strength determiner 730. The path/coupling loss value 718 may be a predefined design parameter or may be a value derived by the path/coupling loss determiner 760. The receive/transmit (RX/TX) relationship 762 may be a predefined design parameter or may be a derived value indicating the relationship between downlink path loss on the femtocell 200 and uplink path loss on the femtocell 200. The HNB/HUE relationship 764 may be a predefined design parameter or may be a derived value indicating the relationship between the uplink path loss on the femtocell 200 and the uplink path loss on the HUE 520. The transmit power value 762 may include a value indicating the transmit power used by the macrocell 560.

Referring to fig. 5 and 7, when the HUE520 communicates with the femto node 700, it may cause interference to a nearby macrocell base station 560. This interference may be very high when the HUE520 is very far away from the femto node 700, such that the HUE520 must adjust its transmit power to be very high. This interference is even more pronounced if the macrocell base station 560 is very close to the HUE520 and the femto node 700. Embodiments of the present invention monitor and detect interference on the macrocell base station 560, estimate whether the interference is caused by the HUE520 communicating with the femto node 700, and adjust the transmit power of the HUE520 in an attempt to reduce interference on the macrocell 560.

In many cases, the HUE520 may be handed off from the femto node to the macro cell 560 if the path loss from the HUE520 to the femto node 700 is very large, for example, if they are a large distance apart, or an obstacle is interfering with the communication. However, in many cases, it is desirable to keep the HUE520 in communication with the femto node 700 as much as possible, rather than with the macro cell 560. As a non-limiting example, users have an economic advantage in operator cost when using the HUE520 relative to the macro cell 560. Additionally, to free up communication bandwidth on the macro cell 560, it may be desirable to keep the HUE520 in communication with the femto node 700 if the interference level on the macro cell 560 can be managed. Thus, in many circumstances, there is a bias towards the HUE520 communicating with the femto node 700 rather than the macro cell 560.

Of course, it may not always be desirable to adjust the transmit power of the HUE 520. If the HUE520 does not cause any interference on the macro cell 560, it is desirable for the HUE520 to manage its transmit power based on normal communications with the femto node 700.

Fig. 8 is a simplified flow diagram of a process for setting transmit power of a user equipment communicating with a femto node. Reference will be made to fig. 5, 7 and 8 in describing the transmit power setting procedure 800.

In operation block 810, the femto node 700 (e.g., HNB) monitors the impact that the user equipment 520 (e.g., HUB) may have on the macro cell 560 when the user equipment 520 is communicating with the femto node 700. This monitoring may take different forms depending on the communication system described below with reference to fig. 9 and 10. In most cases regarding embodiments of the present invention, the femto node 700 only wants to adjust the transmit power of the user equipment 520 if the user equipment 520 causes interference to the macro cell 560. Accordingly, the femto node 700 monitors the macro cell 560 for information that may indicate whether the macro cell 560 is subject to interference from the user equipment 520.

In operation block 830, the femto node 700 determines a desired transmit power of the user equipment 520 that can reduce interference caused by the user equipment 520 on the macro cell 560.

In operation block 850, the femto node 700 sends a message to the user equipment 520 indicating how to adjust the transmit power of the user equipment 520. In operation block 870, if the user equipment 520 is informed that its transmit power needs to be adjusted in accordance with the communication in operation block 850, the user equipment 520 does so.

Of course, it is not always necessary to reduce the transmit power of the user equipment 520. For example, if at some point in time the femto node 700 determines that interference with the visiting access terminal is unlikely, the femto node 700 may decide to direct the user equipment 520 to increase its transmit power.

Decision block 890 represents that the process can continue, if desired, while communication between the user equipment 520 and the femto node 700 is active to further reduce interference on the macro cell 560 by further adjusting the transmit power of the user equipment 520. This loop thus creates a feedback system in which the transmit power of the user equipment 520 can be periodically adjusted to minimize interference to the macro cell 560 while still maintaining sufficient transmit power to communicate with the femto node 700.

Fig. 9 is a more detailed flow diagram of a process 900, the process 900 setting transmit power of a user equipment communicating with a femto node by monitoring a busy indicator from a macro cell. Reference will be made to fig. 5, 7, 8 and 9 in describing a busy indicator procedure 900 for adjusting the transmit power of the user equipment 520. In describing the process of fig. 9, the blocks shown by the dotted lines correspond to the operation blocks having the same reference symbols as those in fig. 8. Thus, fig. 9 shows details of the operations of fig. 8, where the additional details correspond to a busy indicator procedure 900.

In some systems (e.g., CDMA 2000), the macrocell 560 periodically transmits a busy indicator. The macro cell 560 of the access network tracks the total interference level. The access network is configured to determine whether the total interference level is above or below a threshold. If the interference level is below the threshold, which indicates activation of a low level, the access network negates a "busy bit" (which may also be referred to herein as a busy indicator) as being negative (negate). If the interference level is above the threshold, which indicates activation of a high level, the access network causes the busy indicator to be affirmative (alert). The busy indicator is then broadcast to all access terminals in range to inform them of the activation/interference level in the system.

Thus, as shown in operational block 812, some embodiments of the present invention use a busy indication determiner 770 to monitor a busy indicator from the macrocell 560 and store the value or history of values of the indicator in the memory 790 as a busy indicator 772. It is noted that for purposes of embodiments of the present invention, the femto node 700 typically only monitors the busy indicator as a proxy for determining whether the user equipment 520 is causing interference to the macro cell 560. In addition, the femto node 700 correlates the busy indicator 772 with the transmit power of the user equipment 520 to analyze whether the busy indicator 772 is due to the user equipment 520.

In operation block 814, the busy indicator determiner 770 uses the busy indicator 772 from the macrocell 560, a possible past busy indicator 772, and possibly the transmit power of the user equipment 520 to generate a femto busy indicator 774. The femto busy indicator 774 is used to adjust the transmit power of the user device 520 without indicating a level of busy between the femto node 700 and the user device 520.

In the simplest form, the femto busy indicator 774 may simply reflect the value of the busy indicator 772 from the macro cell. However, busy indicator 772 may be transmitted every slot. Thus, for each slot, the femto node 700 may decode the busy indicator 772 and, in some embodiments, generate a filtered version of the busy indicator 772 over time. The filter may include a relatively small time constant to include only busy indicators 772 from a few slots. Alternatively, the time constant may be relatively large to include busy indicator 772 from multiple slots.

In other embodiments, the femto node 700 can monitor the busy indicator 772 both when the user equipment 520 is inactive (e.g., prior to initiating communication with the femto node 700) and when the user equipment 520 is active (e.g., during communication with the femto node 700). If the busy indicator 772 is inactive when the user equipment 520 is inactive and the busy indicator 772 is active when the user equipment 520 is active, the femto node 700 can infer that the change in the busy indicator 772 was caused by the user equipment 520. Thus, the femto node asserts the femto busy indicator 774.

Decision block 832 tests the current value of the femto busy indicator 774 to determine what the femto node 700 should transmit to the user device 520.

If the femto busy indicator 774 is affirmative, then the femto node 700 sends an affirmative version of the femto busy indicator 774 to the user device 520, per block 854. On the other hand, if the femto busy indicator 774 is negative, then the femto node 700 sends a negative version of the femto busy indicator 774, or does not send the femto busy indicator 774 at all, to the user device 520, per block 854.

In operation block 870, the user equipment 520 receives the femto busy indicator 774 and decodes it into a regular busy indicator, and if the user equipment 520 receives the busy indicator from the macro cell 560 while communicating with the macro cell 560, the user equipment 520 typically responds by reducing or increasing its transmit power. As a non-limiting example, one means for adjusting the transmit power of the user equipment 520 is by decreasing or increasing its uplink data rate.

Decision block 890 is the same as discussed above for creating a feedback system when desired to continue adjusting the transmit power of user equipment 520 while communication is active.

Fig. 10 is a more detailed flow diagram of a process 1000 for setting the transmit power of user equipment communicating with a femto node by monitoring the received signal power from a macro cell. Reference will be made to fig. 5, 7, 8 and 10 in describing a received signal power process 1000 for adjusting the transmit power of user equipment 520. In describing the process of fig. 10, the blocks shown by the dotted lines correspond to the operation blocks of the same reference symbols as in fig. 8. Accordingly, fig. 10 shows details of the operation of fig. 8, with additional details corresponding to a received signal power procedure 1000.

In process 1000, the femto node 700 monitors for signals from the macro cell 560, as is done by conventional UEs. With this signal monitoring, the femto node can estimate the interference caused by the user equipment 520 on the macro cell 560 using the interference monitor 744 in conjunction with the signal strength determiner 720, the received pilot strength determiner 730, and the path/coupling loss determiner 760.

At operation block 822, the femto node 700 detects the received signal power from the macro cell 560. In some embodiments, the signal strength determiner 720 may determine a total received signal strength value (e.g., received signal strength indication, RSSI). In some embodiment values, the received pilot strength determiner 730 may determine a signal strength value (e.g., received signal code power, RSCP) associated with the pilot.

In some systems, the broadcast control channel BCCH carries a repeating pattern of system information messages that are used to describe the configuration and available characteristics of the system. These messages may include the current transmit power of the macrocell base station 560.

At decision block 824, the femto node 700 determines whether a broadcast value of the current transmit power is available. If so, operation block 826 instructs the femto node pair to detect the current transmit power and use the broadcast value.

If the broadcast value of the current transmit power is not available, operation block 828 instructs the femto node 700 to obtain a transmit power value 762 from the memory 790. The transmit power value 722 may be a preset value of the most likely transmit power of the macro cell, or the transmit power value 722 may be sent to the femto node 700 by other means (e.g., the wide area network 540).

Operation block 829 represents path/coupling loss determiner 760 determining the downlink path loss. The path loss on the downlink experienced at the femto node 700 may be estimated as:

PL (dB) ═ CPICH _ Tx _ Power-received Power equation 1

Where CPICH _ Tx _ Power is the common pilot channel transmit Power, whether from a broadcast value or a transmit Power value 762 determined by non-broadcast means, the received Power is the determined received signal strength.

The received signal strength (e.g., received signal code power, RSCP) may be measured by the signal strength determiner 720 or the received pilot strength determiner 730, which may determine a signal strength value associated with the pilot signal as Ecp/Io (e.g., pilot signal ratio).

The signal strength determiner 720 may determine the signal strength in various ways. For example, in some implementations, the femto node 700 measures signal strength (e.g., the receiver 714 monitors the appropriate channel). In some implementations, information regarding signal strength may be received from another node (e.g., a home access terminal). This information may take the form of, for example, actual signal strength measurements (e.g., from a node measuring signal strength) or information that may be used to determine a signal strength value.

In some implementations, the received pilot strength can be estimated from the total received signal strength. For example, the determination may be based on a known or estimated relationship between pilot strength and total strength embodied in the form of a pilot/total signal strength relationship 732 (e.g., a function, table, or graph) stored in memory 790. In this implementation, the signal strength determiner 720 may include a received pilot signal strength determiner 720.

Operation block 842 represents interference monitor 744 correlating the femto uplink path loss with the downlink path loss. The correlation may be estimated based on RX/TX relationship 762 information from memory 790. Operation block 844 illustrates the interference monitor 744 estimating the user equipment uplink pathloss from the femto uplink pathloss using HNB/HUE relationship 764 information from memory 790. If the user equipment 520 is relatively close to the femto node, the estimation will be very correct and less correct as the user equipment 520 moves away from the femto node 700. Accordingly, the femto node 700 can add a margin (margin) in the estimation to account for the bias.

Operation block 846 represents that transmit power determiner 750 determines an acceptable transmit power value for user equipment 520 based on the estimated user equipment uplink path loss. As a non-limiting example, in some systems, the femto node 700 may specifically signal a maximum limit on the total power of the user equipment 520. In other systems, this signaling may not be present. However, the femto node 700 may still limit the data rate of the user equipment 520 by: the busy indicator is sent or the user equipment 520 is made more conservative when signaling a more conservative Medium Access Control (MAC) parameter to determine the data rate.

Thus, the femto node 700 may send an "up" command to instruct the HUE520 to increase its transmit power or a "down" command to instruct the HUE520 to decrease its transmit power. Or transmit power level commands to set specific power levels.

In operational block 870, the user equipment 520 receives and decodes the TPC command and responds by decreasing or increasing its transmit power according to the indication of the TPC command.

Decision block 890 is the same as described above for creating a feedback system when desired to continue adjusting the transmit power of user equipment 520 while communication is active.

The components described herein may be implemented in various ways. Referring to fig. 11, an apparatus 1100 is represented as a series of interrelated functional blocks. In some aspects, the functionality of these blocks may be implemented as a processing system including one or more processor components. In some aspects, the functionality of these blocks may be implemented using, for example, at least a portion of one or more integrated circuits (e.g., an ASIC). As described 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 disclosed herein.

Apparatus 1100 may include one or more modules for performing one or more of the functions described above with respect to the various figures. For example, the interference level monitoring module may correspond to an interference monitor, such as described herein. For example, acceptable transmit power determination module 1104 may correspond to a transmit power determiner as described herein. Power limit transmitting module 1106 may correspond to, for example, a transmitter as described herein. Busy indicator receiving module and femto busy indicator generating module 1108 may correspond to, for example, a busy indicator determiner as described herein.

It will be understood that the use of designations such as "first", "second", etc. to indicate elements generally does not limit the number or order of such elements. Rather, these designations may be used herein as a convenient method for distinguishing between two or more elements or instances of an element. Thus, reference to first and second elements does not mean that only two elements may be employed or that the first element must precede the second element. Further, unless otherwise specified, a set of elements may include one or more 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, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

The various illustrative logical blocks, modules, and circuits described in connection with the embodiments disclosed herein may be implemented or performed with 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, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the general purpose 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.

The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in storage media such as Random Access Memory (RAM), flash memory, read-only memory (ROM), Electrically Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In the alternative, the processor and the storage medium may reside as discrete components in a user terminal.

In one or more exemplary embodiments, the functions described herein may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a computer. Such computer-readable media can include, for example, but is not limited to, RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code in the form of computer-accessible instructions or data structures. Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc (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.

The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to these disclosures will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the spirit or 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 disclosed herein.

Claims (25)

1. A method for wireless communication, comprising:

at a femto node:

monitoring an interference level from user equipment communicating with the femto node to a macrocell base station;

determining an acceptable transmit power for the user equipment based on the interference level;

sending a power limit from the femto node to the user equipment based on the acceptable transmit power;

on the user equipment:

adjusting the transmit power of the user equipment if the power limit indicates.

2. The method of claim 1, wherein:

monitoring the interference level further comprises:

receiving a busy indicator from the macrocell base station;

generating a femto busy indicator from the busy indicator;

determining the acceptable transmit power further comprises:

determining that the acceptable transmit power needs to be reduced from a current transmit power if the femto busy indicator is affirmative;

transmitting the power limit further comprises:

sending a negative femto busy indicator to the user equipment if the acceptable transmit power needs to be maintained;

sending a positive femto busy indicator to the user equipment if the acceptable transmit power needs to be reduced.

3. The method of claim 1, wherein:

monitoring the interference level further comprises:

detecting a received signal power from the macrocell base station;

determining a transmit signal power from the macrocell base station;

evaluating the transmit signal power and the receive signal power to determine a downlink path loss;

determining the acceptable transmit power further comprises:

estimating from the user equipment to the macro cell based on the downlink path loss

An uplink path loss of the base station;

determining the acceptable transmit power from the downlink path loss;

transmitting the power limit comprises transmitting the acceptable transmit power.

4. The method of claim 3, wherein the transmit signal power is determined from a broadcast message received from the macrocell base station.

5. The method of claim 3, wherein the transmit signal power is determined according to a preset value or a value received through a wide area network.

6. The method of claim 3, wherein estimating the uplink path loss comprises:

correlating a femto uplink pathloss with the downlink pathloss;

estimating the uplink pathloss from the femto uplink pathloss.

7. The method of claim 1, further comprising:

repeating the following actions to further fine tune the transmit power of the user equipment:

the level of said interference is monitored and,

the acceptable transmit power is determined and,

the acceptable transmit power is transmitted at the time of the transmission,

adjusting the transmit power.

8. A femto node, comprising:

a busy indicator determiner for detecting a busy indicator from a macrocell base station in proximity to the wireless communication device and generating a femto busy indicator from the busy indicator;

a communication controller to send the femto busy indicator to a user equipment in communication with the femto node.

9. The femto node of claim 8, wherein the busy indication determiner is further to: generating the femto busy indicator by filtering a plurality of busy indicators received from the macrocell base station over time.

10. The femto node of claim 8, wherein the busy indication determiner is further to:

detecting a previous busy indicator from the macrocell base station prior to a communication link between the femto node and the user equipment;

detecting a current busy indicator from the macrocell base station during the communication link;

if the current busy indicator is negative, then causing the femto busy indicator to be negative;

if the previous busy indicator is negative and the current busy indicator is positive, then the femto busy indicator is made positive.

11. A femto node, comprising:

a signal strength determiner for measuring received signal power from a macro cell base station proximate to the femto node;

a path loss determiner to calculate a downlink path loss at the femto node;

an interference monitor to correlate an uplink pathloss on user equipment in communication with the femto node with the downlink pathloss on the femto node;

a transmit power determiner for determining an acceptable transmit power for the user equipment based on the uplink path loss at the user equipment; and

a communication controller for transmitting the acceptable transmit power to the user equipment.

12. The femto node of claim 11, wherein the path loss determiner calculates the downlink path loss by:

decoding a broadcast value of a current transmit power from the macrocell base station;

subtracting the received signal power from the current transmit power.

13. The femto node of claim 11, wherein the path loss determiner calculates the downlink path loss by:

estimating a current transmit power from the macrocell base station based on at least one of a predetermined value and a value received from a communication over a wide area network;

subtracting the received signal power from the current transmit power.

14. The femto node of claim 11, wherein the path loss determiner is further configured to:

correlating a femto uplink pathloss with the downlink pathloss at the femto node;

estimating the uplink pathloss at the user equipment from the femto uplink pathloss.

15. The femto node of claim 11, wherein the communication controller transmits the acceptable transmit power to the user equipment as a limit on the transmit power, a limit on the data rate, or a combination thereof.

16. A femto node, comprising:

means for monitoring an interference level from a user equipment communicating with the femto node to a macrocell base station;

means for determining an acceptable transmit power for the user equipment based on the interference level;

means for transmitting a power limit from the femto node to the user equipment based on the acceptable transmit power.

17. The femto node of claim 16, wherein:

the means for monitoring interference levels further comprises:

means for receiving a busy indicator from the macrocell base station; and

means for generating a femto busy indicator from the busy indicator;

the means for determining acceptable transmit power further comprises:

means for determining that the acceptable transmit power needs to be reduced from a current transmit power if the femto busy indicator is affirmative;

the means for transmitting a power limit further comprises:

means for sending a negative femto busy indicator to the user equipment if the acceptable transmit power needs to be maintained;

means for sending a positive femto busy indicator to the user equipment if the acceptable transmit power needs to be reduced.

18. The femto node of claim 16, wherein:

the means for monitoring interference levels further comprises:

means for detecting a received signal power from the macrocell base station;

means for determining a transmit signal power from the macrocell base station; and

means for evaluating the transmit signal power and the receive signal power to determine a downlink path loss;

the means for determining acceptable transmit power further comprises:

means for estimating an uplink pathloss from the user equipment to the macrocell base station according to the downlink pathloss;

means for determining the acceptable transmit power based on the downlink path loss;

the means for transmitting a power limit comprises transmitting the acceptable transmit power.

19. The femto node of claim 18, wherein the transmit signal power is determined from a broadcast message received from the macrocell base station.

20. The femto node of claim 18, wherein the transmit signal power is determined according to a preset value or a value received over a wide area network.

21. The femto node of claim 18, wherein the means for estimating uplink pathloss comprises:

means for correlating a femto uplink pathloss with the downlink pathloss; and

means for estimating the uplink pathloss from the femto uplink pathloss.

22. A computer program product, comprising:

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

monitoring an interference level from a user equipment in communication with a femto node to a macrocell base station;

determining an acceptable transmit power for the user equipment based on the interference level;

sending a power limit from the femto node to the user equipment based on the acceptable transmit power.

23. The computer program product of claim 22, wherein:

the code for causing the computer to monitor the interference level further causes the computer to:

receiving a busy indicator from the macrocell base station;

generating a femto busy indicator from the busy indicator;

the code for causing the computer to determine the acceptable transmit power further causes the computer to:

determining that the acceptable transmit power needs to be reduced from a current transmit power if the femto busy indicator is affirmative;

the code for causing the computer to transmit the power limit further causes the computer to:

sending a negative femto busy indicator to the user equipment if the acceptable transmit power needs to be maintained;

sending a positive femto busy indicator to the user equipment if the acceptable transmit power needs to be reduced.

24. The computer program product of claim 22, wherein:

the code for causing the computer to monitor the interference level further causes the computer to:

detecting a received signal power from the macrocell base station;

determining a transmit signal power from the macrocell base station;

evaluating the transmit signal power and the receive signal power to determine a downlink path loss;

the code for causing the computer to determine the acceptable transmit power further causes the computer to:

estimating an uplink path loss from the user equipment to the macrocell base station from the downlink path loss;

determining the acceptable transmit power from the downlink path loss;

the code for causing the computer to transmit the power limit also causes the computer to transmit the acceptable transmit power.

25. The computer program product of claim 24, wherein the code for causing the computer to estimate the uplink path loss further causes the computer to:

correlating a femto uplink pathloss with the downlink pathloss;

estimating the uplink pathloss from the femto uplink pathloss.