Signalling for interference management in HETNETs

The method and apparatus disclosed herein enable interference suppressed information (information about interference after interference suppression to be provided to the Radio Network Controller (RNC) and/or to surrounding Radio Base Stations (RBSs)), thereby providing better radio resource management for hot spots and/or allowing the RBSs to better understand their impact on surrounding cells. Generally, a network node in the wireless network signals interference suppressed information, e.g., an interference suppressed load or overload indicator, an interference suppressed neighbor cell interference, and/or an interference suppressed noise floor to a remote node in the wireless network to facilitate radio resource management. Further, a radio network controller in the wireless network may manage the interference in cells based on the interference suppressed information by generating an interference management instruction based on the interference suppressed information, and sending the interference management instruction to the radio base station to control one or more interference management settings, e.g., a power control setting, a load threshold, etc.

The present invention relates generally to signaling information between network nodes, e.g., between a Radio Base Station (RBS) and a Radio Network Controller (RNC), and more particularly relates to signaling of information about the interference after suppression information to facilitate network management operations, particularly those in heterogeneous networks (HETNETs).

BACKGROUND

There has been an increased interest in recent years in deploying low-power nodes, e.g., pico, micro, and femto base stations as well as relay nodes, home NodeBs/eNodeBs, relays, remote radio heads, etc., to enhance the macro network performance of the wireless network in terms of the network coverage, capacity, and service experience of individual users. With the increased interest in such deployments has come the realization that there is a need for enhanced interference management techniques to address the arising interference issues caused, for example, by the transmit power variations among different cells. In the past, such interference management techniques have not been necessary because lower-power nodes have generally been used for indoor environments, and therefore, have been isolated from most forms of interference. Thus, conventional radio resource management techniques do not consider information about the interference after suppression, referred to herein as interference suppressed information. For example, indoor environments generally experience good isolation from interference caused by macro-layer transmissions. However, lower-power nodes are now being considered for outdoor environments, and for capacity enhancement in general, where interference management is more critical.

Heterogeneous networks, where low-power nodes of different transmit powers are placed throughout a macro-cell layout to cope with nonuniform traffic distribution, have been subject to standardization in 3GPP. Deployment of such technology is effective for capacity extension in certain areas, e.g., small geographical areas with higher user density and/or higher traffic intensity known as traffic hot spots. Further, heterogeneous deployments may also be used to adopt the wireless network to the traffic needs and the environment. However, the mix of all of these different nodes introduces interaction between the cells in new ways, e.g., reuse-one networks where the inter-cell isolation is poor.

To address this interaction, some types of mobile communication systems, such as Wideband Code Division Multiple Access (WCDMA) systems, may use interference suppression (IS) to achieve better performance in terms of peak data rates, coverage, system throughput, and system capacity. Examples of commonly used interference suppressing receivers include the G-rake+ receiver, the Frequency Domain Equalizer (FDE) receiver, and the Frequency Domain Pre-Equalize (FDPE) receiver. As future wireless networks become more heterogeneous in terms of wireless devices, deployed radio network nodes, traffic demand, service types, radio access technologies, etc., incorporating such interference suppression with network management operations becomes increasingly important. However, the air interface load interaction, e.g., the effects of the interference created in one cell for the surrounding cells, becomes particularly difficult in WCDMA heterogeneous networks equipped with interference suppression receivers. Appendix A provides some details regarding existing technologies in this area.

To illustrate, consider a low power cell with limited coverage intended to serve a traffic hotspot, where the low-power cell is located in the interior and at the boundary of a specific macro cell. In this case, the low-power cell may use an interference suppression receiver, e.g., a G-RAKE+ receiver, to provide sufficient coverage for the hot spot. Surrounding macro cells interfere with the low-power cell, rendering a high level of neighbor cell interference in the low power cell that does not allow coverage of the hotspot, despite the use of an advanced IS receiver. Such interference only increases when transmissions in the low-power cells are at the maximum power level. As a result, the users of the hot spot are connected to the surrounding macro cells, which further increase the neighbor cell interference experienced by the low-power cell.

Recent work by the inventors of the present application has provided ways to estimate various types of interference suppressed information, e.g., interference suppressed neighbor cell interference. However, there are currently no provisions for signaling such interference suppressed information between an RBS and an RNC, between two RNCs, etc. Further, there are currently no provisions for radio resource management using such interference suppressed information. Thus, there remains a need for further network management options based on interference suppressed information.

SUMMARY

The solution disclosed herein addresses these problems by providing a method and apparatus that enable interference suppressed information comprising information about the interference after suppression to be provided to the RNC and/or to surrounding radio network nodes, e.g., Radio Base Stations (RBSs) and/or Location Management Units (LMUs), thereby providing better radio resource management for hot spots and/or allowing the RBSs to better understand their impact on surrounding cells. Generally, a network node in the wireless network signals interference suppressed information, e.g., an interference suppressed load or interference suppressed overload indicator, an interference suppressed neighbor cell interference, and/or an interference suppressed noise floor to a remote node in the wireless network to facilitate radio resource management. Further, a radio network controller in the wireless network may manage the interference suppressed information by generating an interference management instruction based on the interference suppressed information, and sending the interference management instruction to the radio network node to control one or more interference management settings. Exemplary interference management instructions include but are not limited to power setting instructions, admission control instructions, congestion control instructions, scheduling instructions, handover instructions, load balancing instructions, etc.

One exemplary embodiment provides a network node configured to signal interference suppressed information to one or more remote nodes in a wireless network. Accordingly, the network node comprises an information unit and a signaling unit. The information unit determines the interference suppressed information comprising at least one of an interference suppressed load or interference suppressed overload indicator, an interference suppressed neighbor cell interference, and an interference suppressed noise floor associated with a radio network node (e.g., an RBS or an LMU) in the wireless network. For example, when the network node comprises a radio base station, the information unit determines the interference suppressed information by suppressing interference from a received signal and determining the interference suppressed information from the interference-suppressed signal. Alternatively, when the network node comprises a radio network controller, the information unit determines the interference suppressed information by requesting and receiving the interference suppressed information from the radio base station. In any event, the signaling unit signals the interference suppressed information to a remote node in the wireless network, e.g., a radio network controller, a radio base station, etc., via an interface communicatively coupling the network node to the remote node.

Another exemplary embodiment provides a method of signaling interference suppressed information between network nodes in a wireless network. The method comprises determining the interference suppressed information comprising at least one of an interference suppressed load or interference suppressed overload indicator, an interference suppressed neighbor cell interference, and an interference suppressed noise floor associated with a base station in the wireless network. The method further comprises signaling the interference suppressed information to a remote network node in the wireless network via an interface communicatively coupling the network node to the remote network node.

In another exemplary embodiment, a management node manages interference suppressed information in a wireless network, where the management node comprises a receiver, a processor, and a signaling unit. The receiver receives interference suppressed information comprising at least one of an interference suppressed load or interference suppressed overload indicator, an interference suppressed neighbor cell interference, and an interference suppressed noise floor associated with a first base station in the wireless network from the first base station. The processor processes the interference suppressed information to generate an interference management instruction. The signaling unit signals the interference management instruction to one or more base stations in the wireless network.

According to an exemplary method of managing interference suppressed information in a wireless network, interference suppressed information is received, where the interference suppressed information comprises at least one of an interference suppressed load or interference suppressed overload indicator, an interference suppressed neighbor cell interference, and an interference suppressed noise floor associated with a first base station in the wireless network from the base station. The method further includes processing the interference suppressed information to generate an interference management instruction, and signaling the interference management instruction to one or more base stations in the wireless network to control one or more interference management control settings at each of the one or more base stations.

DETAILED DESCRIPTION

The methods and apparatus disclosed herein enable interference suppressed information to be provided to the Radio Network Controller (RNC) and/or to surrounding Radio Base Stations (RBSs) and/or Location Management Units (LMUs) to provide better management of traffic hot spot operations and/or to allow the RBSs to better understand their impact on surrounding cells. As used herein, the term “interference suppressed information” refers to information about the interference after interference suppression, such as may be provided by a G-RAKE+, a Frequency-Domain Equalizer (FDE), a Frequency-Domain Pre-Equalizer (FDPE), etc., and includes e.g., an interference suppressed load or interference suppressed overload indicator, an interference suppressed neighbor cell interference, and/or an interference suppressed noise floor. Generally, a network node in the wireless network signals the interference suppressed information to a remote node in the wireless network. When the network node comprises an RNC, the RNC may also manage the RBS/LMU operations by generating an interference management instruction based on the interference suppressed information, and send the interference management instruction to an RBS/LMU to control one or more interference management settings. Exemplary interference management instructions include but are not limited to power setting instructions, admission control instructions, congestion control instructions, scheduling instructions, handover instructions, load balancing instructions, etc.

FIG. 1shows an RBS100communicatively coupled to an RNC200in a mobile communication network10via an interface50, which may comprise a wireless or a wired interface50. RBS100provides service to a plurality of user terminals20within a cell12served by the RBS100. The RBS100receives signals of interest from the mobile terminals20on an uplink (UL) channel, and also receives interfering signals from user terminals20in neighboring cells. Thus, for example, mobile terminal “A” would likely experience interfering signals from mobile terminals “B” and “C” which reside in neighboring cells. In WCDMA systems, the RBS100controls the transmit power of the mobile terminal20over the UL channel so that the received signal power from each mobile terminal20is approximately equal. While not explicitly shown inFIG. 1, the RBS100inFIG. 1may alternatively represent a Location Management Unit (LMU). It will be appreciated that operations herein attributed to the RBS100may alternatively be implemented in LMU.

Exemplary embodiments will be described herein in terms of a Wideband Code Division Multiple Access (WCDMA) Heterogeneous Network (HETNET). Those skilled in the art will appreciate, however, that the method(s) and apparatus(es) disclosed herein are more generally applicable to any wireless communication systems that signal and manage interference suppressed information.

FIG. 2shows an exemplary network node300, which comprises one of the RBS100and the RNC200. Network node300comprises an interference suppression (IS) information unit310and a signaling unit330. Generally, IS information unit310determines interference suppressed information comprising at least one of an interference suppressed load or interference suppressed overload indicator, an interference suppressed neighbor cell interference, and an interference suppressed noise floor associated with an RBS100in the wireless network. Subsequently, the signaling unit330signals the interference suppressed information to a remote node in the wireless network via an interface50communicatively coupling the network node300to the remote node. For example, the signaling unit330may signal the interference suppressed load in terms of an interference suppressed rise-over-thermal, or in terms of an interference suppressed noise rise determined based on the interference suppressed neighbor cell interference. Alternatively or additionally, the signaling unit330may signal a total wideband cell power in terms of the interference suppressed noise floor, or may signal the interference suppressed neighbor cell interference.

FIG. 3shows an exemplary method400for signaling the interference suppressed information between network nodes in a wireless network. The method400includes determining interference suppressed information (block410), where the interference suppressed information includes an interference suppressed load or interference suppressed overload indicator, an interference suppressed neighbor cell interference, and/or an interference suppressed noise floor associated with a base station in the wireless network. For example, the interference suppressed information may be calculated at an RBS100or it may be requested and received by an RNC200. The interference suppressed information is subsequently signaled from the network node300that determined the interference suppressed information to a remote network node in the wireless network via an interface (block420). For example, when RBS100determines the interference suppressed information, the RBS100may signal the interference suppressed information to an RNC200. Alternatively, when the RNC200determines the interference suppressed information, the RNC200may signal the interference suppressed information to an RBS100or another RNC200. Appendix B provides a non-limiting list of examples of signaling operations.

While not required, the signaled information may be signaled for a subset of time and/or frequency domain resources, e.g., a subset of transmission time intervals (TTIs) and/or a subset of frequency sub-carriers. The subset of TTIs may be organized by, for example, node layers. For example, pica nodes may transmit in the first subset of TTIs and macro nodes may transmit in a second subset of TTIs, where the two subsets of TTIs may or may not overlap in time. In this case, an indicator, e.g., a carrier, a pattern reference/index, an indication of using specially designed as low-interference subframes, etc., may be transmitted together with the signaled interference suppressed information to indicate that the signaled information corresponds to a subset of resources. It will further be appreciated that different interference suppressed information may be obtained for and signaled for different TTIs.

In one exemplary embodiment, the network node300comprises an RBS100, and the remote network node comprises a network controlling node, e.g., RNC200, an Operation and Maintenance (O&M) node, or a Self-Organizing Network (SON) node. Accordingly,FIG. 4shows an exemplary IS information unit310for an RBS network node300. In this embodiment, IS information unit310comprises an interference suppression unit312and a measurement unit314. A receiver110in the RBS100processes an input signal provided by an antenna (not shown) to generate a received signal input to the IS unit312. IS unit312suppresses interference from the received signal to determine an interference suppressed signal. Exemplary IS units312include, but are not limited to, G-RAKE+ units, frequency domain equalization units, and frequency domain pre-equalization units. Measurement unit314processes the interference suppressed signal to determine the interference suppressed information. For example, measurement unit314may determine an interference suppressed rise-over-thermal based on the interference suppressed signal to determine an interference suppressed load. Alternatively, the measurement unit314may determine interference-suppressed neighbor cell interference based on the interference suppressed signal to determine the interference suppressed load, and/or may determine an interference suppressed noise rise based on the interference suppressed neighbor cell interference. It will be appreciated that the IS information unit310in the RBS100may use any method for determining the interference suppressed information, including but not limited to those techniques disclosed in Appendices C-H. In another example, RBS300may comprise a multi-standard RBS, and the remote network node may comprise another RBS or a network node, e.g., a SON, O&M, etc. It will further be appreciated that the interference may be measured on a pre-defined time domain and/or frequency domain radio resources, which may be useful when, e.g., radio resources are divided into sets and the interference is different in different sets.

Responsive to the interference suppressed information determined by the IS information unit310in the RBS100, the signaling unit330signals the interference suppressed information to the remote network node, e.g., the RNC200, another RBS100, etc. For example, to signal the interference suppressed information, the interface between the RBS100and the RNC200, e.g., the lub interface, may be augmented with Information Elements (IEs) used to signal the desired interference suppressed information. For example, the Common Measurement Report message and the Common Measurement Response message may be augmented with IEs. Alternatively or additionally, the desired interference suppressed information values may be encoded relative to the noise power floor given by the Reference Received Total Wideband Power IE in the same message. In this case, the interference suppressed information would be encoded in dBs in the same manner as the existing IE for the Received Total Wideband Power (RTWP). In another embodiment, the desired interference suppressed information values may be encoded as the existing IE Received Scheduled E-DCH Power Shared (RSEPS), which uses a relative coding to RTWP. The encoding could alternatively be made relative to a new Reference Received Total Wideband Power after interference suppressions, provided such an IE is standardized according to the implementation disclosed herein. Alternatively, the interference suppressed information may be transparently signaled between RBSs100via a user terminal20. In still another embodiment, when the RBS100comprises a multi-RAT or multi-standard RBS, the interference suppressed information may be signaled from the RBS100using single-RAT or specific multi-RAT interfaces, per RAT and per cell.

In another exemplary embodiment, the network node300comprises an RNC200, and the remote network node comprises an RBS100or a network controlling node, e.g., another RNC200, O&M node, or a SON node. Accordingly,FIG. 5shows an exemplary IS information unit310when the network node300comprises the RNC200. In this embodiment, IS information unit310comprises a requesting unit316and a receiver318. The requesting unit316sends a request for the interference suppressed information to a RBS100, while the receiver318receives the requested interference suppressed information from the RBS100. For example, the requesting unit316may request the interference suppressed information by sending a Common Measurement Type message that includes a corresponding indicator. The request may indicate that the interference suppressed information should be reported periodically to the RNC200, or may be event triggered. Further, the request may be specific to each cell12or to each RBS100in a cell12.

Responsive to the interference suppressed information determined by the IS information unit310in the RNC200, the signaling unit330signals the interference suppressed information to the remote network node, e.g., another RNC200, the RBS100that provided the interference suppressed information, another RBS100, etc. For example, to signal the interference suppressed information between two controlling nodes, e.g., between two RNCs200, the Common Measurement Report message and the Common Measurement Response message may be augmented with IEs for signaling any one or more of the interference suppressed information values. To signal the interference suppressed information from the RNC200to an RBS100, the lub interface may be used. In still another embodiment, when the RBS100comprises a multi-RAT or multi-standard RBS, the interference suppressed information may be signaled from the RNC200to the RBS100using single-RAT or specific multi-RAT interfaces, per RAT and per cell.

Network node300may also implement management operations directed to controlling various communication parameters, e.g., power control, load threshold control, etc., based on the interference suppressed information. In this case, the network node300may additionally comprise a coordinating node, e.g., an RNC200, an O&M node, a SON, or a coordinating Radio Resource Management (RRM) node, where the IS information unit310in the coordinating node includes a coordinating unit320, as shown inFIG. 5, that further processes the received interference suppressed information to generate an interference management instruction. The signaling unit330subsequently signals the interference management instruction to an RBS100in the network10, e.g., the RBS100that calculated the interference suppressed information and/or another RBS100. In this case, the RBS100may also include a management unit325(FIG. 4), where the receiver110provides the received interference management instruction to the coordinating unit325, and the coordinating unit325executes the received interference management instruction. For example, the coordinating unit325may implement power control, admission control, congestion control, scheduling control handover control, and/or load balancing control responsive to the interference management instruction. While not required, the signaled management instruction may be obtained from interference suppressed information determined for a subset of time and/or frequency domain resources, e.g., a subset of transmission time intervals and/or a subset of frequency sub-carriers. When the RBS100comprises a multi-RAT or multi-standard RBS, the signaled management instruction may be used by joint functional blocks, e.g., for multi-RAT admission control, scheduling, load balancing, interference management, or power sharing. Appendix I provides a non-limiting list of examples of coordinating operations.

In one exemplary embodiment, the interference suppressed information includes the uplink neighbor cell interference and/or uplink load estimates after interference suppression, where the RBS100adjusts the maximum downlink transmit power based on this interference suppressed information. In this example, the downlink power control may be implemented dynamically, and may also be used for power sharing in multi-RAT and/or multi-standard RBSs100. One advantage of such downlink power control is that such downlink power control can be done autonomously by a radio network node100, e.g., home NodeB. This advantage is based on the observation that the estimated high uplink interference at a radio network node100with small coverage may indicate the presence of a nearby mobile terminal20transmitting at a high power when, e.g., being served by a large neighbor cell, e.g. a macro cell. Some decision examples for adjusting the transmit power of the radio network node100with small coverage are, e.g., reducing the transmit power of the radio network node100with small coverage in order to reduce the interference in the downlink to the nearby mobile terminals20. Alternatively, if the load of the radio network node100with small coverage allows, e.g. is not too high, then in some examples it may be better to increase the coverage of this radio network node100, e.g., to increase its transmit power, to push away the cell boundary and get the nearby macro cell mobile terminal to reselect and get served to the adjusted radio network node100, and thus avoid uplink interference at the radio network node100and downlink interference at the nearby mobile terminal20. The power adjusting decision may also depend on whether the radio network node100with small coverage uses Closed-Subscriber Groups (CSGs) and whether the mobile terminal20belongs to that group.

In another exemplary embodiment, the interference suppressed information may be used to decide a configuration subset of time resources e.g., the density of blank or low interference time instances. Such resources may be configured, for example, in less loaded cells to temporarily improve interference conditions in a highly loaded or relatively weak (e.g., pica) neighbor cell, or in CSG cells to reduce interference to non-CSG terminals in the corresponding coverage area. The configuration of the time resources may be performed by the RNC200or the RBS100. Further, the configuration of the time resources may be performed by a centralized node, such as the O&M and subsequently distributed to other network nodes.

In still another exemplary embodiment, the interference suppressed information may be used to set an overload indicator, which is subsequently signaled to a network node. The overload indicator may be set based on a comparison between the interference suppressed information and a pre-defined threshold, and may be signaled between any node, e.g., from the RBS100to the RNC200, from the RNC200to a network controlling node, e.g., the O&M, between RBSs100, etc. The overload indicator may also be transparently transmitted between RBSs100via a user terminal20.

The management operations generally address the previously described load interaction problems, which are shown inFIG. 6, which shows the reduced coverage of the center cell as a result of higher or overestimated interference, by executing the following exemplary algorithm, which is intended to be run consecutively in the background for the cells of the system. In one exemplary embodiment, the coordinating unit320in the RNC200coordinates management of the interference suppressed information by implementing the following:1. Determine if the received interference suppressed rise-over-thermal is too high (indicating a loss of coverage. If not, proceed to step 5; else proceed to step 2.2. Determine if the interference suppressed neighbor-cell interference is also too high. If not, proceed to step 2b; else proceed to step 2a.a. If the interference suppressed neighbor-cell interference is too high, proceed to step 4.b. If the interference suppressed own-cell interference is too high, proceed to step 3.3. Use an algorithm to change the admission control threshold of the own-cell, to accept fewer user terminals20in the own cell (or to allocate another frequency carrier for a multi-RAT or multi-carrier system)) and shrink the coverage of this cell, with a first predefined step (in dBs). Proceed to step 5. In one example, the admission threshold may be any of the number of user terminals20, the worst target service quality or GBR level, the lowest received signal strength, etc.4. Use an algorithm to change the admission control thresholds of the surrounding cells, to admit fewer user terminals20in the surrounding neighbor cells and shrink their coverage areas.a. Check the own-cell noise rise level relevant for stability after interference suppression (not the RoT level which is corrupted by neighbor cell interference) of each of the surrounding cells, and select the surrounding with the highest value (most likely to cause problems).b. Generate a management instruction to reduce the admission control threshold of the surrounding cell with the highest value of the interference suppressed noise rise relevant for stability, with a second predefined step (in dBs) to accept fewer user terminals20in that cell12(or to allocate another frequency carrier for a multi-RAT or multi-carrier system) and shrink its coverage area.c. Mark the cell12as one with a reduced admission control threshold.d. Proceed to step 5.5. In case the cell is marked as one with a reduced threshold, determine if the interference suppressed rise-over-thermal is too high. If it is too high, end; else proceed to step 6.6. Generate a management instruction to increase the admission control threshold with a third predefined step (in dBs), maximally up to the pre-defined admission control threshold.
It will be appreciated that the above algorithm represents a typical non-limiting embodiment. Thus, other alternatives may be used.

Upon receipt of the interference management instruction from the RNC200at the RBS100, the coordinating unit325in RBS100may execute the received interference management instruction. For example, coordinating unit325may:1. Determine if the interference suppressed noise rise is among the predetermined number with the highest value of the cells signaled from the RNC200, indicating that this RBS100is creating too much neighbor cell interference. If so, proceed to step 2; else proceed to step 3.2. Reduce the scheduling threshold for the own UL load a first pre-determined step (in dBs). Mark the threshold as reduced. Start a timer during which increases of the threshold are blocked, where the scheduling threshold may be the number of scheduled user terminals20over a given period of time.3. Determine if the scheduling threshold for the own UL load is marked as reduced, and if the interference suppressed noise figure is among the predetermined number with the highest value of the cells signaled from the RNC200, indicating that this RBS100is still creating too much neighbor cell interference. If so, proceed to step 5; else proceed to step 4.4. Determine if the scheduling threshold for the own UL load is marked as reduced. If the increase of the threshold is blocked, end; else proceed to step 5.5. Increase the scheduling threshold for the own UL load a second predetermined step (in dBs), maximally up to the pre-defined or default scheduling threshold for the own UL load.

The signaling and/or management operations associated with interference suppressed information as disclosed herein provide previously unavailable information to any network node300in the wireless network. The RNC200, for example, can then perform HETNET load management by the use of novel admission control algorithms. The RNC200can also signal the above information, valid for a specific cell ID to all surrounding RBSs, thereby allowing also RBSs to perform HETNET load management by the use of novel algorithms.

The interference suppressed information being signaled between network nodes and/or used for management operations is determined by the RBS100. It will be appreciated that the RBS node may use any method for determining the interference suppressed information, including those techniques disclosed in Appendices C-H. The following provides one example for providing the interference suppressed information comprising interference suppressed neighbor cell interference estimation, which may, e.g., be implemented in the measurement unit314.

First, the neighbor cell interference is estimated using the received signal before interference suppression. The idea is to modify a Kalman filter of a front end of a receiver so that the internally estimated state becomes the sum of neighbor cell interference and thermal noise. More particularly, the modified Kalman filter performs a joint estimation of the RTWP power, PRTWP(t), and the sum of the neighbor cell interference power and the thermal noise power floor, Pneighbor(t)+PN(t), before interference suppression. It will be appreciated that the modified Kalman filter may be implemented as part of the IS information unit310. Alternatively, when receiver110comprises an interference suppression receiver, and the received signal output by receiver110comprises an interference suppressed received signal the modified Kalman filter may be implemented in a processing unit, e.g., processor108, preceding the receiver110in the signal chain.

The modified Kalman filter performs the joint estimation using measurements of PRTWP(t) determined by the IS information unit310, with a sampling rate of TRTWP=kRTWPTTI for kRTWPεZ+, where Z+ represents a set of positive integers, and using computed own-cell load factors Lown(t), with a sampling of TL(t)=kLεZ+ for kLεZ+. For example, the own-cell load factors may be computed in a load factor processor106and input into processor108. The IS information unit310subsequently selects the state as:
x1(t)=Pneighbor(t)+PN(t).  (1)

The measured signal available for processing is PRTWP(t), which may be generated by process108. The Lown(t) is a computed quantity, e.g., based on signal-to-noise ratio measurements. For example, Lown(t) may be computed according to:

⁢Lown=∑u=1U⁢⁢PuPRTWP=∑u=1U⁢⁢(C/I)u1+(C/I)u⁢⁢⁢where(2)(C/I)u⁢(t)=SINRu⁡(t)Wu⁢RxLossG×(1+βDPDCH,u2⁡(t)+βEDPCCH,u2⁢(t)+ncodes,u⁡(t)⁢βEDPDCH,u2⁡(t)+βHSDPCCH,u2⁡(t)βDPCCH2⁡(t)).(3)
Here Wurepresents the spreading factor for user u, RxLoss represents missed receiver energy, G represents the diversity gain, and the β's represent the beta factors of the respective channels (assuming non-active channels have zero beta factors). A measured model of PRTWP(t) may then be generated in terms of the states, computed quantities, and a measurement uncertainty. To that end, Equation (2) is used together with a delay TDthat models the scheduling loop delay of WCDMA to compute PRTWP(t) according to:
PRTWP(t)=Lown(t−TD)PRTWP(t)+Pneighbor(t)PN(t),  (4)
which results in:

PRTWP⁡(t)=11-Lown⁡(t-TD)⁢(Pneighbor⁡(t)+PN⁡(t)).(5)
After the addition of a zero-mean white measurement noise eRTWP(t) and replacement of variables by Equation (1), the following time variable measurement equation results:

yRTWP⁡(t)=x1⁡(t)1-Lown⁡(t-TD)+eRTWP⁡(t)(6)R2,RTWP⁡(t)=E⁢eRTWP2⁡(t).(7)
Here, yRTWP(t)=PRTWP(t) and R2,RTWP(t) represents the scalar covariance matrix of eRTWP(t) Note: Lown(t) is computed using both enhanced uplink and R99 traffic, and therefore, the delay is valid for both.

To set up the optimal filtering algorithm, it is necessary to generate a model for propagation of the state. This may be solved by postulating the most simple such model, e.g., a random walk as given by Equation (8), which is a standard statistical model often used in Kalman filtering.
x(t+TTTI)≡x1(t+Tm)=x1(t)+w1(t)  (8)
R1(t)=E[w1(t)]2.  (9)
Here, R1(t) represents the covariance matrix of the zero mean white disturbance. The state space model behind the Kalman filter is:
x(t+T)=A(t)x(t)+B(t)u(t)+w(t)  (10)
y(t)=C(t)x(t)+e(t)  (11)
Here, x(t) represents the state vector, u(t) represents an input vector, y(t) represents an output measurement vector comprising the power measurements performed cell, e.g., the total received wideband power RTWP, w(t) represents the so-called systems noise that represents the modeled error, and e(t) represents the measurement error. The matrix A(t) represents the system matrix describing the dynamic modes, the matrix B(t) represents the input gain matrix, and the vector C(t) represents the measurement vector, which may be time varying. Finally, t represents the time and T represents the sampling period.

The general case with a time varying measurement vector is considered here. The Kalman filter is then given by the following matrix and vector iterations after the initialization, where the initialization is given by t=t0, {circumflex over (x)}(0|−1)=x0, and P(0|−1)=P0.
t=t+T
Kf(t)=P(t|t−T)CT(t)(C(t)P(t|t−T)CT(t)+R2(t))−1
{circumflex over (x)}(t|t)={circumflex over (x)}(t|t|T)+Kf(t)(y(t)−C(t){circumflex over (x)}(t|t−T))
P(t|t)=P(t|t−T)−Kf(t)C(t)P(t|t−T)
{circumflex over (x)}(t+T|t)=Ax(t|t)+Bu(t)
P(t+T|t)=AP(t|t)AT+R1(t)  (12)

where {circumflex over (x)}(t|t−T) represents the state prediction based on data up to time t−T, {circumflex over (x)}(t|t) represents the filter update based on data up to time t, P(t|t−T) represents the covariance matrix of the state prediction based on data up to time t−T, P(t|t) represents the covariance matrix of the filter update based on data up to time t, C(t) represents the measurement matrix, Kf(f) represents the time variable Kalman gain matrix, R2(t) represents the measurement covariance matrix, and R1(t) represents the system noise covariance matrix. It will be appreciated that R1(t) and R2(t) often used as tuning variables for the filter. In principle, the bandwidth of the Kalman filter is controlled by the matrix quotient of R1(t) and R2(t).

The quantities of the Kalman filter for estimation of the sum of neighbor cell interference and noise power can now be defined. Using the state and measurement equations it follows that:

The final processing step is provided by the algorithms for noise power floor estimation, which operate on the Gaussian distribution of the state {circumflex over (x)}1(t). Representing the estimated noise floor by PN(t), it follows that the estimated neighbor cell interference becomes:
Îneighbor(t)≡{circumflex over (P)}neighbor(t)={circumflex over (x)}(t)−PN(t).  (18)
As explained in Appendix D, and particularly Equation D2, the interference suppressed neighbor cell interference via G-RAKE+ is obtained by scaling Equation (18) according to:
Îu,neighborG+=wHwÎneighbor(19)
In Equation (19), the user dependence shown in Equation D2 has been removed because Equation (18) is obtained for the complete cell. Similar expressions may be obtained for the FDE and FDPE by using the neighbor cell interference before interference suppression in Equations H3 and F3, respectively. The interference suppressed noise floor may be computed in the baseband of the RBS100from a scale factor expressing the effect of the interference suppression and the noise floor calculated before interference suppression, e.g., as calculated in Equation (19).

In addition to signaling the interference suppressed information, the signaling unit330may also signal a network nodes' capability using a capability indication, where “capability” refers to the network node's ability to deal with various levels of interference and report the interference suppressed information. While not required, the capability indication may also indicate whether interference suppression has been applied to the reported information. In any event, such capability signaling may be especially beneficial in high-interference scenarios or heterogeneous network deployments, where network nodes300having different capabilities are deployed in the same area. It will be appreciated that the capability indication may be provided responsive to a request, or may be provided independent of a request, e.g., with a measurement reporting or when an RBS100registers with the network10, and that the capability information may be signaled to any controlling network node300, e.g., an RNC and/or an O&M. A controlling network node300may factor in the capability information with the interference suppressed information when making decisions about future wireless communications in the network10.