HK1227187B - User equipment, evolved node b, and method for reducing signal interference - Google Patents

Abstract

Technology for reducing signal interference is disclosed. Semi-static signaling can be received at a user equipment (UE) from a neighboring evolved node (eNB). The semi-static signaling can include potential configurations of signal parameters used at the neighboring eNB. The UE can receive dynamic signaling from the neighboring eNB that includes a subset of the potential configurations of signal parameters used at the neighboring eNB. Signal interference that is caused by the neighboring eNB can be reduced using the semi-static signaling and the dynamic signaling.

Description

User equipment, evolved node B and method for reducing signal interference

Background

Wireless mobile communication technology uses various standards and protocols to communicate data between a node (e.g., a transmitting station) and a wireless device (e.g., a mobile device). Some wireless devices communicate using Orthogonal Frequency Division Multiple Access (OFDMA) in Downlink (DL) transmissions and single carrier frequency division multiple access (SC-FDMA) in Uplink (UL) transmissions. Standards and protocols for signal transmission using Orthogonal Frequency Division Multiplexing (OFDM) include the third generation partnership project (3GPP) Long Term Evolution (LTE), the Institute of Electrical and Electronics Engineers (IEEE)802.16 standards (e.g., 802.16e, 802.16m) known to the industry group as WiMAX (worldwide interoperability for microwave access), and the IEEE 802.11 standard known to the industry group as WiFi.

In a 3GPP Radio Access Network (RAN) LTE system, a node may be a combination of an evolved universal terrestrial radio access network (E-UTRAN) node B (also commonly denoted as evolved node B, enhanced node B, eNodeB, or eNB) and a Radio Network Controller (RNC), which communicates with wireless devices, referred to as User Equipment (UE). Downlink (DL) transmissions may be communications from a node (e.g., eNodeB) to a wireless device (e.g., UE), and Uplink (UL) transmissions may be communications from the wireless device to the node.

In a homogeneous network, nodes (also referred to as macro nodes) may provide basic radio coverage to wireless devices in a cell. A cell may be an area in which a wireless device is operable to communicate with a macro node. Heterogeneous networks (hetnets) can be used to handle traffic load aggravation on macro nodes due to increased usage and functionality of wireless devices. Hetnets may include a planned high power macro node (or macro eNB) layer overlaid with a layer of lower power nodes (small enbs, micro enbs, pico enbs, femto enbs, or home enbs (henbs)) that may be deployed within the coverage area (cell) of the macro node in a less planned manner or even in a completely uncoordinated manner. The Lower Power Nodes (LPNs) may be generally referred to as "low power nodes," small nodes, or small cells.

In LTE, data may be sent from an eNodeB to a UE via a Physical Downlink Shared Channel (PDSCH). A Physical Uplink Control Channel (PUCCH) may be used to confirm that data has been received. The downlink and uplink channels or transmissions may use time division multiplexing (TDD) or frequency division multiplexing (FDD).

Drawings

Features and advantages of the present disclosure will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the features of the present disclosure; and wherein:

fig. 1A illustrates intra-cell interference between multiple User Equipments (UEs) within the same cell, according to an example;

fig. 1B illustrates inter-cell interference between multiple User Equipments (UEs) within a neighboring cell, according to an example;

fig. 2 illustrates semi-static signaling between a neighboring evolved node B (eNB) and a User Equipment (UE) and dynamic signaling between the neighboring eNB and the UE for interference mitigation at the UE, according to an example;

fig. 3 illustrates semi-static signaling between a neighboring evolved node B (eNB) and a User Equipment (UE) via a serving eNB and dynamic signaling directly between the neighboring eNB and the UE for interference mitigation at the UE, according to an example;

fig. 4 illustrates functionality of a User Equipment (UE) operable to reduce signal interference according to an example;

fig. 5 depicts functionality of a neighboring evolved node B (eNB) operable to facilitate reducing signal interference according to an example;

fig. 6 depicts a flow diagram of a method for reducing signal interference according to an example; and

fig. 7 shows a diagram of a wireless device (e.g., UE) according to an example.

Reference will now be made to the exemplary embodiments illustrated, and specific language will be used herein to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended.

Detailed Description

Before the present invention is disclosed and described, it is to be understood that this invention is not limited to the particular structures, process steps, or materials disclosed herein, but is extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It is also to be understood that the terminology used herein is for the purpose of describing particular examples only and is not intended to be limiting. Like reference symbols in the various drawings indicate like elements. The numerals provided in the flowcharts and processes are provided to clarify the steps and operations and do not necessarily indicate a particular order or sequence.

Example embodiments

An initial overview of technical embodiments is provided below, followed by a further detailed description of specific technical embodiments. This initial summary is intended to assist the reader in understanding the present technology more quickly, and is not intended to identify key features or essential features of the present technology, nor is it intended to limit the scope of the claimed subject matter.

Techniques for reducing signal interference at a User Equipment (UE) using Network Assisted Interference Cancellation and Suppression (NAICS) are described. The UE may be served by a serving evolved node B (eNB). The UE may be adjacent to a cell edge within a cell served by the serving eNB. In a neighboring cell, a neighboring eNB may cause signal interference to a UE. To enable the UE to mitigate signal interference, the neighboring eNB may periodically transmit semi-static signaling to the UE. In one configuration, the neighboring eNB may send semi-static signaling to the UE via the serving eNB. For example, the neighboring eNB may send semi-static signaling to the serving eNB via the backhaul link, and the serving eNB may then forward the semi-static signaling via unicast transmission.

Semi-static signaling may include potential configurations of signal parameters used at neighboring enbs. For example, the semi-static signaling may include a physical resource fast (PRB) allocation granularity, a subset of supported transmission modes, an indication to use PRB hopping at a neighboring eNB, a maximum number of layers for downlink transmission, a maximum modulation order, an uplink-downlink configuration of a frame, a subset of power offset values, and/or a scrambling identification subset for a defined transmission mode. The UE may use the potential configuration of signal parameters in semi-static signaling to reduce signal interference from neighboring enbs. For example, the UE may perform blind detection based on potential configurations of signal parameters in order to reduce signal interference.

Further, the neighboring eNB may send dynamic signaling including a subset of the potential configurations of signal parameters directly to the UE. A subset of the potential signal parameter configurations may be used in a given downlink subframe at the neighboring eNB. In one example, the subset of potential configurations of signal parameters is the actual configuration of signal parameters used at the neighboring eNB (different from the range of possible configurations provided in semi-static signaling). The neighboring eNB may be triggered to send dynamic signaling when selecting at least one of the potential configurations of signal parameters or modifying signal parameters in an existing configuration. The dynamic signaling may also include Physical Resource Block (PRB) allocation granularity, a subset of supported transmission modes, an indication to use PRB hopping at a neighboring eNB, a maximum number of layers for downlink transmission, a maximum modulation order, an uplink-downlink configuration of a frame, a subset of power offset values, and/or a scrambling identification subset for a defined transmission mode. However, dynamic signaling may be more accurate and up-to-date than semi-static signaling. The UE may use a subset of potential configurations of signal parameters in dynamic signaling to reduce signal interference from neighboring enbs.

Capacity of third generation partnership project (3GPP) Long Term Evolution (LTE) advanced (LTE) (LTE-a) networks may be increased by deploying heterogeneous networks to achieve cell splitting gain and multi-user (MU) multiple-input multiple-output (MIMO). In both scenarios, co-channel interference from inter-cell users or co-scheduled intra-cell users is expected to be a major limiting factor in achieving higher network capacity. While MU-MIMO transmission may significantly improve cell throughput (or cell capacity) due to MU diversity compared to Single User (SU) transmission, users scheduled for MU-MIMO may experience strong signal interference if the channel state information at the base station (or evolved node B (eNB)) is outdated or in a small cell with a limited number of users available. In MU-MIMO, the throughput of a User Equipment (UE) may depend on the amount of interference from co-scheduled users. Signal interference may be managed at the eNB through efficient precoding or via interference cancellation at the UE. To mitigate signal interference at the UE, the UE may employ information about the interfering data streams in the decoding process, which may result in performance gains by reducing signal interference.

Fig. 1A illustrates intra-cell interference between multiple User Equipments (UEs) within the same cell. An evolved node B (eNB)104 may serve both the first UE 102 and the second UE 106. The first UE 102 and the second UE 106 may be within the same cell (i.e., within a cell). Further, the first UE 102 and the second UE 106 may transmit data using the same carrier frequency. Intra-cell interference between the first UE 102 and the second UE 106 may occur in either the Uplink (UL) or Downlink (DL) direction.

Fig. 1B illustrates inter-cell interference between a plurality of UEs in neighboring cells. For example, a first UE 114 may be served by a first eNB112 and a second UE 116 may be served by a second eNB 118. The first UE 114 and the second UE 116 may be within neighboring cells. The first UE 114 may experience interference from the second eNB118 and the second UE 116 may experience interference from the first eNB112 (i.e., inter-cell interference). In one example, both the first UE 114 and the second UE 116 may be located at cell edges within their respective cells, as a result of which they are more susceptible to interference from enbs in neighboring cells. The first UE 114 may experience interference when the second UE 116 is simultaneously transmitting or receiving data. Further, the first eNB112 and the second eNB118 are connected via a backhaul link.

In conventional 3GPP LTE release 11 systems, coordinated multipoint (CoMP) techniques can be used to mitigate this interference, which helps to avoid interference at the transmitting base station (i.e., the network side). These cooperative transmissions between neighboring cells may reduce interference in the downlink. Furthermore, performing interference mitigation at the UE side by taking into account the spatial properties of the interference has also shown promising gains in spectral efficiency. Furthermore, enhanced receiver-side interference mitigation may be achieved by considering more advanced receiver algorithms that may exploit additional information about the interference structure. For example, the UE may be provided with knowledge about interference aspects such as, but not limited to, transmission mode, resource allocation granularity, presence of interference, and reference symbols. The UE may also be referred to as an interference cancellation receiver or an interference suppression receiver. Thus, further enhancements to intra-cell and inter-cell interference at the receiver side can be achieved by improving the knowledge level about interfering transmissions to the UE together with possible coordination from the network. Such interference cancellation receivers may be considered for performance improvement of different physical channels (e.g., Physical Downlink Shared Channel (PDSCH), Physical Downlink Control Channel (PDCCH), enhanced downlink control channel (EPDCCH), etc.).

The UE may reduce interference and improve throughput performance by using linear processing techniques. More advanced receiver architectures may use non-linear techniques. The non-linear structure may utilize additional information (e.g., parameters) about the interfering signal. That is, the UE may perform interference suppression if the UE knows certain parameters about the interfering signal. These parameters describing the interfering signal may include modulation order, Precoding Matrix Indicator (PMI), number of layers, transmission mode, and the like. As an example, the UE may use a modulation order to know that the interfering signal is not an arbitrary signal, but is present at a particular point. The UE may utilize this information to better suppress interference from neighboring cells. In one configuration, the parameters may be estimated at the UE receiver from the received signal. That is, the UE may detect interfering signals (e.g., from an eNB of a neighboring cell) and then estimate these signal parameters from the interfering signals. However, in some cases, estimating signal parameters from interfering signals may be unreliable and complex for practical implementation. Further, estimating the signal parameters may result in additional power usage at the UE.

To reduce UE complexity and improve performance, semi-static signaling of interfering signal parameters is being considered in 3GPP Technical Report (TR) 36.866. That is, rather than the UE estimating the signal parameters itself, the UE may utilize network assistance (e.g., receiving semi-static signaling) to obtain the signal parameters of the interfering signal. One drawback of this approach is that semi-static signaling implies semi-static restriction of indicated parameters over a large number of frames. That is, the UE may use the signal parameters in semi-static signaling to perform interference suppression, but if the signal parameters change over time, the UE may not notice the change because the signaling is "semi-static" or less frequent. Thus, the UE may continue to perform interference suppression using outdated signal parameters. Such long term limitations may degrade the performance of the interfering cells and are therefore undesirable.

The eNB causing interference (via interfering signals) to the UE may be referred to as a neighboring eNB. The eNB causing the interference may also be referred to as an aggressor eNB or an interfering eNB. When the neighboring eNB reconfigures some of the signal parameters, the UE may not receive updated reconfiguration in time through semi-static signaling. In conventional techniques, a neighboring eNB may communicate reconfiguration of signal parameters to other enbs. Upon receiving the reconfigured signal parameters from the neighboring eNB, each of the other enbs may process or incorporate the reconfigured signal parameters of the interfering eNB. Thus, each reconfiguration of signal parameters at a neighboring eNB results in a relatively large amount of signaling between other enbs. As a result, the UE may not receive the updated configuration of signal parameters in a timely manner and may continue to use the outdated signal parameter configuration to perform interference reduction or suppression.

Thus, the current art describes providing semi-static signaling from a neighboring cell (or neighboring eNB) to a UE, as well as dynamic signaling. The semi-static signaling may indicate one or more possible interference configurations on the neighboring cell (or neighboring eNB). The dynamic signaling may indicate the actual interference configuration that has been implemented in a particular subframe of the neighboring eNB. Dynamic signaling may be transmitted directly from the neighboring eNB to the UE. The UE may use both semi-static signaling and dynamic signaling to reduce or suppress interference from neighboring enbs in the neighboring cells. That is, the UE may use hybrid signaling (i.e., both semi-static signaling and dynamic signaling) to reduce interference. Alternatively, the UE may use both semi-static signaling and dynamic signaling to reduce or suppress interference from other UEs within the same cell. In addition to semi-static signaling, by providing dynamic signaling to the UE, previous long-term limitations on signal parameters used to perform interference reduction may be eliminated. Furthermore, hybrid signaling may reduce complexity at the UE by relieving the UE of the burden of independently determining signal parameters.

Fig. 2 illustrates providing semi-static signaling and dynamic signaling to a User Equipment (UE)220 to enable the UE220 to perform signal interference mitigation. The UE220 may be within a cell served by a serving evolved node B (eNB) 210. In one example, the UE220 may be adjacent to a cell edge within a cell being served by the serving eNB 210. The neighboring eNB230 may be within a neighboring cell relative to the cell served by the serving eNB 210. That is, the serving eNB210 and the neighbor eNB230 may be located in neighboring cells. The neighboring eNB230 may refer to an eNB that causes signal interference to the UE220 being served by the serving eNB 210. The neighboring eNB230 may also be referred to as an aggressor eNB or an interfering eNB, i.e., because the eNB is interfering with Uplink (UL) and/or Downlink (DL) transmissions at the UE 220. The serving eNB210 may also be referred to as a victim eNB. The serving eNB210 may be considered a "victim" because the UE being served by the serving eNB210 may experience signal interference from the neighboring eNB 230. The UE220 may also be considered a "victim" because of signal interference experienced at the UE220 from the neighboring eNB 230.

The UE220 may periodically receive semi-static signaling from a neighboring evolved node B (eNB)230 via the serving eNB 210. For example, the neighboring eNB230 may communicate semi-static signaling to the serving eNB210 via the backhaul link 215, and the serving eNB210 may then forward the semi-static signaling to the UE 220. In one example, the serving eNB210 may forward the semi-static signaling to the UE220 via unicast transmission. The semi-static signaling may include possible configurations of signal parameters used at the neighboring eNB 230. That is, possible configurations of signal parameters may describe or characterize the interfering signals transmitted from the neighboring eNB 230. The UE220 may use possible configurations of signal parameters in semi-static signaling to reduce or suppress interference from the neighboring eNB 230. For example, the UE220 may perform blind decoding using possible configurations of signal parameters in order to reduce interference from the neighboring eNB 230. If the UE220 knows of possible configurations of signal parameters being implemented at the neighboring eNB230, the UE220 may use this information to reduce the impact of interfering signals on the UE 220.

In one example, semi-static signaling may include possible configurations of Physical Resource Block (PRB) allocation granularity used at the neighboring eNB 230. The neighboring eNB230 may use the PRB tiles to schedule UEs being served by the neighboring eNB 230. The neighboring enbs 230 may use different resource allocation granularities based on traffic conditions, whether voice over IP (VoIP) is being used, etc. As non-limiting examples, possible configurations of PRB allocation granularity may include one PRB or four PRBs, and these possible configurations may be provided to the UE 220. The UE220 may use PRB allocation granularity to reduce interference from neighboring enbs.

The semi-static signaling may include a subset of the transmission modes supported at the neighboring eNB 230. For example, semi-static signaling may indicate support of Transmission Modes (TM)9 and TM 10 at the neighboring eNB 230. That is, semi-static signaling may indicate that both TM 9 and TM 10 are supported at the neighboring eNB230, but may not indicate which specific TM is currently being used at the neighboring eNB 230. However, the UE220 may use a subset of the supported transmission modes to reduce interference from the neighboring eNB 230.

The semi-static signaling may include an indication that PRB hopping is used at the neighboring eNB 230. In some examples, the neighboring eNB230 does not use distributed PRBs, but rather localized (localized) PRB allocation. The neighboring eNB230 may use PRB hopping in some cases. If the neighboring eNB230 uses PRB hopping, the neighboring eNB230 may indicate that PRB hopping is used in a particular subframe. When the neighboring eNB230 performs PRB hopping, the UE220 may adjust certain processing algorithms for such resource allocation, which may allow the UE220 to reduce interference from the neighboring eNB 230.

The semi-static signaling may include a maximum number of layers for downlink transmission. That is, semi-static signaling may provide the UE220 with an upper limit on the number of layers that have been used at the neighboring eNB 230. The maximum number of layers may refer to the number of spatial layers used for downlink transmission when multiple antennas are used. In previous solutions, the UE220 would blindly detect how many layers are used in the neighboring eNB 230. In the current art, semi-static signaling may provide the maximum number of layers (or the possible range of maximum number of layers) to the UE220, so that the complexity of reducing interference may be reduced due to fewer blind decoding estimates at the UE 220.

The semi-static signaling may include a maximum modulation order used at the neighboring eNB 230. The modulation order may refer to a number of bits per Resource Element (RE). For example, the modulation order may be from 2 to 6. In one example, the semi-static signaling may include a possible range of maximum modulation orders (e.g., 4 or 6 bits per RE), such that the complexity of reducing interference may be reduced due to fewer blind decoding estimates at the UE 220. That is, providing the range of maximum modulation orders to the UE220 may reduce blind detection complexity at the UE220, as the UE220 does not need to search for all possible modulations.

The semi-static signaling may include a subset of scrambling identities for transmission mode 10(TM 10). If there are scrambling codes used for reference signals in TM 10, these scrambling codes can be initialized. That is, the neighboring eNB230 may use the set of scrambling codes. The index of the scrambled content used by the neighboring eNB230 may be included in the semi-static signaling. The scrambling identity may be included in semi-static signaling to the UE220 in order to reduce the complexity of blind detection of scrambling sequences used by neighboring enbs 230.

Thus, the semi-static signaling may include potential configurations of signal parameters, such as PRB allocation granularity, a subset of supported transmission modes, an indication of whether PRB hopping is used at the neighboring eNB230, a maximum number of layers for downlink transmission, a maximum modulation order, an uplink-downlink configuration of a frame, a subset of power offset values, and/or a subset of scrambling identities for defined transmission modes. While the UE220 may perform blind detection and reduce signal interference from the neighboring eNB230 using potential configurations of signal parameters in semi-static signaling, the performed blind detection measurements are too complex for the UE220 and consume a large amount of power for the UE. Since semi-static signaling may often only provide a range of possible values or signal parameter configurations, the UE220 still needs to consume a relatively large amount of computational power to check for possible signal parameter configurations included in the semi-static signaling. Furthermore, the periodicity of the semi-static signaling may cause potential configurations of signal parameters to be outdated. That is, the neighboring eNB230 may modify one of its signal parameters, but the UE220 may not be aware of the modification for a relatively long period of time because the updated semi-static signaling is not frequently provided to the UE 220. As a result, the UE220 may attempt to perform blind detection using outdated signal parameter configurations, which may reduce the likelihood that the UE220 successfully reduces or suppresses interference from the neighboring eNB 230.

In one configuration, the neighboring eNB230 may send dynamic signaling to the UE220 that includes a subset of the potential configurations of signal parameters. In addition to semi-static signaling, the neighboring eNB230 may also send dynamic signaling. The signal parameters included in the dynamic signaling may currently be used for a particular downlink subframe or subset of downlink subframes at the neighboring eNB 230. In one example, the subset of potential configurations of signal parameters is the actual configuration of signal parameters used at the neighboring eNB230 (as opposed to the range of possible configurations provided in semi-static signaling). Alternatively, the subset of potential configurations of signal parameters may be an exact (or reduced) range of possible signal parameter configurations as compared to potential configurations of signal parameters included in the semi-static signaling. That is, the information included in the dynamic signaling may be a subset of the information previously included in the semi-static signaling.

The neighboring eNB230 may be triggered to send dynamic signaling when selecting at least one of the potential configurations of signal parameters or modifying signal parameters in an existing configuration. In one example, the neighboring eNB230 may broadcast dynamic signaling. The UE220 may detect the broadcast and determine that one or more signal parameter configurations at the neighboring eNB230 have been modified. In an alternative configuration, the neighboring eNB230 may send dynamic signaling to the serving eNB210 via the backhaul link 215, and the serving eNB210 may forward the dynamic signaling to the UE 220. However, sending dynamic signaling via the serving eNB210 may result in additional signaling when the neighboring eNB230 updates or modifies an existing configuration of signal parameters.

The UE220 may use dynamic signaling (as well as semi-static signaling) broadcast from the neighboring eNB230 to perform blind detection and reduce interference from the neighboring eNB 230. The dynamic signaling may be the actual configuration of the signal parameters (or a reduced range of possible configurations of the signal parameters) used at the neighboring eNB 230. Thus, the UE220 may perform blind detection more efficiently (than using only semi-static signaling) in order to reduce interference from the neighboring eNB 230. Furthermore, dynamic signaling may be more accurate and up-to-date than semi-static signaling. As a result, the UE220 may more quickly be aware of the modifications at the neighboring eNB230 and change the UE's interference reduction or suppression techniques accordingly to account for the modified signal parameters used at the neighboring eNB 230.

The dynamic signaling may include a subset of potential configurations of signal parameters, e.g., an updated PRB allocation granularity, an updated subset of supported transmission modes, an updated indication of whether PRB hopping is used at the neighboring eNB230, an updated maximum number of layers for downlink transmission, an updated maximum modulation order, an updated uplink-downlink configuration of a frame, a subset of updated power offset values, and/or an updated subset of scrambling identifications for defined transmission modes. The UE may use a subset of the potential configurations of signal parameters (or updated signal parameter configurations) in the dynamic signaling to reduce signal interference from the neighboring eNB 230. As previously described, the subset may include a reduced set of possible signal parameter configurations or the actual signal parameter configuration used at the neighboring eNB 230.

In one example, the UE220 may use both dynamic signaling and semi-static signaling to reduce interference from the neighboring eNB 230. As non-limiting examples, the UE220 may use semi-static signaling for PRB allocation granularity, PRB hopping, maximum number of layers for downlink transmission, and dynamic signaling for transmission mode, maximum modulation order, and scrambling identity in order to reduce interference from the neighboring eNB 230.

In one example, the neighboring eNB230 may initially send semi-static signaling to the UE220 indicating a PRB allocation granularity of four PRBs. However, four PRBs may not be ideal for certain situations (e.g., VoIP UEs that typically have narrowband allocations). Accordingly, the neighboring eNB230 may dynamically change the resource allocation to a smaller size (e.g., one PRB) in order to deliver VoIP traffic. The neighboring eNB230 may dynamically inform the UE220 of the updated PRB allocation granularity using dynamic signaling broadcast to the UE 220. Thus, the neighboring eNB230 may indicate that the resource allocation granularity has changed from four PRBs to one PRB. The dynamic signaling may be a direct indication from the neighboring eNB230 as to the actual resource allocation granularity currently used on a particular subframe or set of subframes at the neighboring eNB 230.

In another example, the neighboring eNB230 may initially send semi-static signaling to the UE220 indicating that both TM 9 and TM 10 are supported at the neighboring eNB 230. That is, the neighboring eNB230 may indicate that either TM 9 or TM 10 may be used. Later, the neighboring eNB230 may send dynamic signaling indicating that TM 10 is currently being used in a particular subframe. Accordingly, the UE220 may use the updated transmission mode when performing interference suppression.

In another example, the neighboring eNB230 may initially transmit semi-static signaling to the UE220 indicating the determined range of the maximum number of layers for downlink transmission used at the neighboring eNB 230. Later, the neighboring eNB230 may send dynamic signaling indicating a reduced range of maximum number of layers for downlink transmission (compared to the range previously defined included in the semi-static signaling). Since the neighboring eNB230 may dynamically change the maximum number of layers from one downlink subframe to another, dynamic signaling enables the UE220 to receive an updated indication of the maximum number of layers in a timely manner. Similarly, the neighboring eNB230 may dynamically change the maximum modulation order, thus, dynamic signaling enables the UE220 to receive an indication of the updated maximum modulation order in a timely manner.

In one example, the UE220 may reduce interference based on the specific transmission mode used in a particular PRB at the neighboring eNB 230. In previous solutions, the UE220 would perform blind detection in all possible transmission modes (e.g., TM 1-10). The UE220 will blindly detect the actual transmission mode used by the neighboring eNB230 for each PRB. In the present technique, complexity at the UE may be reduced when the neighboring eNB230 generates two possible subsets of transmission modes. The first subset may be TM1-5 and the second subset may be TM 5-10. The neighboring eNB230 may transmit the first subset and the second subset to the UE220 in semi-static signaling. Subsequently, the neighboring eNB230 may indicate that the subset TM1-5 is being used via dynamic signaling provided to the UE220, which may reduce the search space (and complexity) of the UE 220. In an alternative example, the dynamic signaling may indicate to the UE220 that TM 3 or TM 4 is being used at the neighboring eNB 230. The UE220 may use this information to determine how signals in neighboring cells are constructed, and the UE220 may therefore use this information to suppress interference.

In one example, the neighboring eNB230 may be configured with two PRB allocation granularities of one PRB pair and X neighboring PRB pairs, where X is an integer greater than one. In one example, X may be equal to a Resource Block Group (RBG). The first or second allocation granularity may be signaled to the UE220 depending on the actual scheduling decision performed at the neighboring eNB 230. In another example, two subsets of transmission modes may be configured, e.g., { TM 2, TM 3, TM 4} or { TM1-10 }. Depending on the actual scheduling decisions performed at the neighboring eNB230, a set of actual transmission modes from the two subsets may be provided to the UE 220. In another example, PRB hopping may be enabled or disabled depending on scheduling decisions performed at the neighboring eNB 230. Actual information about the use of PRB hopping may be provided to the UE220 via dynamic signaling.

Based on the dynamic signaling received from the neighboring eNB230, the UE220 may understand which parameters in the semi-static signaling are actually used in a particular downlink subframe at the neighboring eNB 230. As a result, the UE220 may more effectively cancel interference from the neighboring eNB 230. By obtaining the actual signal parameters (and possibly signal parameters from semi-static signaling), the UE220 can detect how interfering signals are constructed in neighboring cells and thus suppress the interfering signals. Further, the UE220 may use less computational capacity to reduce interference based on dynamic signaling. Without dynamic signaling, the UE220 may need to perform blind detection on all possible values in the potential signal parameter configuration, which may result in a large number of computations. If the actual signal parameter values (or a reduced subset of the possible signal parameter values) are provided to the UE in dynamic signaling, the UE220 may blindly detect the reduced number of values.

Fig. 3 illustrates semi-static signaling between a neighboring evolved node B (eNB)330 and a User Equipment (UE)310 via a serving eNB 320 and dynamic signaling directly between the neighboring eNB330 and the UE 310. The neighboring eNB330 may periodically send semi-static signaling to the serving eNB 320, and the serving eNB 320 may forward the semi-static signaling to the UE 310. Semi-static signaling may include potential configurations of signal parameters used at the neighboring eNB 330. For example, the semi-static signaling may include a Physical Resource Block (PRB) allocation granularity, a subset of supported transmission modes, an indication to use PRB hopping at a neighboring eNB, a maximum number of layers for downlink transmission, a maximum modulation order, an uplink-downlink configuration of a frame, a subset of power offset values, and/or a subset of scrambling identifications for defined transmission modes. The UE 310 may use semi-static signaling to reduce interference from the neighboring eNB 330. Further, the UE 310 may receive dynamic signaling from the neighboring eNB 330. The dynamic signaling may include updated potential configurations of signal parameters used at the neighboring eNB 330. Further, the dynamic signaling may include a reduced subset of actual configurations and/or potential configurations used at the neighboring eNB 330. By using both semi-static signaling and dynamic signaling, the UE 310 may perform interference reduction or suppression with a reduced amount of computation and power consumption.

Another example provides functionality 400 of a User Equipment (UE)410 operable to reduce signal interference, as shown in fig. 4. The UE 410 may include a communication module 412 configured to receive semi-static signaling from a neighboring evolved node (eNB)430 via a serving eNB 420. Semi-static signaling may include potential configurations of signal parameters used at the neighboring eNB 430. UE 410 may be located within a cell served by serving eNB 420. The communication module 412 may be configured to receive dynamic signaling at the UE 410 directly from the neighboring eNB 430 that includes a subset of potential configurations of signal parameters used in a particular downlink subframe at the neighboring eNB 430. The UE 410 may include an interference reduction module 414, the interference reduction module 414 configured to reduce signal interference caused by the neighboring eNB 430 at the UE 410 using semi-static signaling comprising a potential configuration of signal parameters and dynamic signaling comprising a subset of the potential configuration of signal parameters.

In one example, the communication module 412 can also be configured to receive dynamic signaling from the neighboring eNB 430 via a Physical Downlink Control Channel (PDCCH) or Enhanced PDCCH (EPDCCH). The communication module 412 can also be configured to receive semi-static signaling from the serving eNB420 via Radio Resource Control (RRC) signaling. The communication module 412 may also be configured to receive semi-static signaling and dynamic signaling from the neighboring eNB 430 according to a defined periodicity.

In one example, the subset of potential configurations of signal parameters is the actual configuration of signal parameters used at the neighboring eNB 430. In another example, the UE 410 is located adjacent to a cell edge within a cell served by the serving eNB420 and experiences signal interference from the neighboring eNB 430. In yet another example, the neighboring eNB 430 is located in a neighboring cell that is close to the serving eNB420 that is serving the UE.

In one example, the communication module 412 can be further configured to receive semi-static signaling from the serving eNB420 via a unicast transmission, wherein the serving eNB420 receives semi-static signaling from the neighboring eNB 430 via a backhaul link. In another example, the subset of the potential configurations of the signal parameters in the semi-static signaling and the potential configurations of the signal parameters in the dynamic signaling includes at least one of: a Physical Resource Block (PRB) allocation granularity, a subset of supported transmission modes, an indication at a neighboring eNB to use PRB hopping, a maximum number of layers for downlink transmission, a maximum modulation order, an uplink-downlink configuration of a frame, a subset of power offset values, or a subset of scrambling identifications for UE-specific reference signals for a defined transmission mode.

In one example, the interference reduction module 414 may also be configured to perform blind detection in order to reduce signal interference caused by the neighboring eNB 430. The UE 410 may perform blind detection using at least one of a potential configuration of signal parameters in semi-static signaling or a subset of potential configurations of signal parameters in dynamic signaling. In another example, the communication module 412 may be further configured to receive dynamic signaling from the neighboring eNB 430 in response to the neighboring eNB 430 selecting at least one of the potential configurations of signal parameters or modifying signal parameters in an existing configuration. In yet another example, the communication module 412 may be further configured to receive dynamic signaling from the neighboring eNB 430 via broadcast transmission.

Another example provides functionality 500 of a neighboring evolved node B (eNB) operable to facilitate reducing signal interference, as shown in the flow diagram in fig. 5. The functionality may be implemented as a method or the functionality may be implemented as instructions on a machine, where the instructions are included on at least one computer readable medium or one non-transitory machine readable storage medium. The neighboring eNB may include one or more processors configured to transmit semi-static signaling to a User Equipment (UE) via the serving eNB, wherein the semi-static signaling includes a potential configuration of signal parameters used at the neighboring eNB, the UE being located within a cell served by the serving eNB, as in block 510. The neighboring eNB may include one or more processors configured to transmit dynamic signaling to the UE, where the dynamic signaling includes a subset of potential configurations of signal parameters used in a particular downlink subframe at the neighboring eNB, as in block 520. In one example, semi-static signaling including potential configurations of signal parameters and dynamic signaling including a subset of the potential configurations of signal parameters enable a UE to reduce signal interference caused by a neighboring eNB at the UE.

In one example, the neighboring eNB can include one or more processors further configured to transmit semi-static signaling to the UE according to a defined periodicity. In another example, the neighboring eNB may include one or more processors further configured to transmit dynamic signaling to the UE in response to selecting at least one of the potential configurations of signal parameters or modifying signal parameters in an existing configuration. In yet another example, a UE that is experiencing signal interference from a neighboring eNB is located adjacent to a cell edge within a cell being served by a serving eNB. Further, the neighboring eNB is located within a neighboring cell that is close to the serving eNB that is serving the UE.

In one example, the neighboring eNB can include one or more processors further configured to transmit semi-static signaling to the serving eNB over the backhaul link, wherein the serving eNB forwards the semi-static signaling to the UE via unicast transmission. In another example, the subset of the potential configurations of the signal parameters in the semi-static signaling and the potential configurations of the signal parameters in the dynamic signaling includes at least one of: a Physical Resource Block (PRB) allocation granularity, a subset of supported transmission modes, an indication at a neighboring eNB to use PRB hopping, a maximum number of layers for downlink transmission, a maximum modulation order, an uplink-downlink configuration of a frame, a subset of power offset values, or a subset of scrambling identifications for UE-specific reference signals for a defined transmission mode. In yet another example, the neighboring eNB may include one or more processors further configured to transmit dynamic signaling to the UE via broadcast transmission.

Another example provides a method 600 for reducing signal interference, as shown in the flow diagram in fig. 6. The method may be performed as instructions on a machine, where the instructions are included on at least one computer-readable medium or one non-transitory machine-readable storage medium. The method may include an operation of receiving semi-static signaling at a User Equipment (UE) from a neighboring evolved node B (eNB), the semi-static signaling including potential configurations of signal parameters used at the neighboring eNB, as in block 610. The method may include an operation of receiving, at the UE, dynamic signaling from a neighboring eNB, the dynamic signaling including a subset of potential configurations of signal parameters used at the neighboring eNB, as in block 620. The method may include an operation of reducing signal interference caused by a neighboring eNB at a UE using semi-static signaling and dynamic signaling, as in block 630.

In one example, the method may further include the operation of performing blind detection using semi-static signaling and dynamic signaling to reduce signal interference caused by neighboring enbs. In another example, the subset of potential configurations of signal parameters is the actual configuration of signal parameters used at the neighboring eNB. In yet another example, a method can include an operation of receiving semi-static signaling from a neighboring eNB via a unicast transmission, wherein the serving eNB receives the semi-static signaling from the neighboring eNB via a backhaul link. Further, the method may comprise the operations of: receiving semi-static signaling from a neighboring eNB according to a predetermined period; and receiving dynamic signaling from the neighboring eNB in response to the neighboring eNB selecting at least one of the potential configurations of signal parameters or modifying signal parameters in an existing configuration.

Fig. 7 provides an example illustration of a wireless device (e.g., User Equipment (UE), Mobile Station (MS), mobile wireless device, mobile communication device, tablet, handset, or other type of wireless device). A wireless device may include one or more antennas configured to communicate with a node, a macro node, a Low Power Node (LPN), or a transmission station (e.g., a Base Station (BS), an evolved node B (eNB), a baseband unit (BBU), a Remote Radio Head (RRH), a Remote Radio Equipment (RRE), a Relay Station (RS), a Radio Equipment (RE), or other type of Wireless Wide Area Network (WWAN) access point). The wireless device may be configured to communicate using at least one wireless communication standard, including 3GPP LTE, WiMAX, High Speed Packet Access (HSPA), bluetooth, and Wi-Fi. The wireless device may communicate using a separate antenna for each wireless communication standard or using a shared antenna for multiple wireless communication standards. The wireless devices may communicate in a Wireless Local Area Network (WLAN), a Wireless Personal Area Network (WPAN), and/or a WWAN.

Fig. 7 also provides an illustration of a microphone and one or more speakers that may be used for audio input and output of the wireless device. The display screen may be a Liquid Crystal Display (LCD) screen or other type of display screen, for example, an Organic Light Emitting Diode (OLED) display. The display screen may be configured as a touch screen. The touch screen may use capacitive, resistive, or another type of touch screen technology. The application processor and the graphics processor may be coupled to internal memory to provide processing and display functions. The non-volatile memory port may also be used to provide data input/output options to a user. The non-volatile memory port may also be used to extend the memory functionality of the wireless device. The keyboard may be integrated with or wirelessly connected to the wireless device to provide additional user input. A virtual keyboard may also be provided using a touch screen.

Various techniques, or certain aspects or portions thereof, may take the form of program code (i.e., instructions) embodied in tangible media, such as floppy diskettes, compact disc read only memories (CD-ROMs), hard drives, non-transitory computer-readable storage media, or any other machine-readable storage medium, wherein, when the program code is loaded into and executed by a machine, such as a computer, the machine becomes an apparatus for practicing the various techniques. The circuit may include: hardware, firmware, program code, executable code, computer instructions, and/or software. The non-transitory computer readable storage medium may be a computer readable storage medium that does not include a signal. In the case of program instructions executing on a programmable computer, the computing device may include: a processor, a storage medium readable by the processor (including volatile and non-volatile memory and/or storage elements), at least one input device, and at least one output device. The volatile and non-volatile memory and/or storage elements may be: random Access Memory (RAM), erasable programmable read-only memory (EPROM), flash drives, optical drives, hard drives, solid state drives, or other media for storing electronic data. The node and the wireless device may further comprise: a transceiver module, a counter module, a processing module and/or a clock module or timer module. One or more programs that may implement or use the various techniques described herein may use an Application Program Interface (API), reusable controls, and the like. The programs may be implemented in a high level procedural or object oriented programming language to communicate with a computer system. However, if desired, the program(s) can be implemented in assembly or machine language. In any case, the language may be a compiled or interpreted language, and combined with hardware implementations.

It should be appreciated that many of the functional units described in this specification have been labeled as modules, in order to more particularly emphasize their implementation independence. For example, a module may be implemented as hardware circuitry comprising: very Large Scale Integration (VLSI) circuits or gate arrays, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components are conventional. A module may also be implemented in programmable hardware devices (e.g., field programmable gate arrays, programmable array logic, programmable logic devices, etc.).

In one example, a plurality of hardware circuits may be used to implement the functional units described in this specification. For example, a first hardware circuit may be used to perform processing operations and a second hardware circuit (e.g., a transceiver) may be used to communicate with other entities. The first hardware circuit and the second hardware circuit may be integrated on a single hardware circuit, or alternatively, the first hardware circuit and the second hardware circuit may be separated on different hardware circuits.

Modules may also be implemented in software for execution by various types of processors. An identified module of executable code may, for instance, comprise one or more physical or logical blocks of computer instructions which may, for instance, be organized as an object, procedure, or function. Nevertheless, the executables of an identified module need not be physically located together, but may comprise disparate instructions stored in different locations which, when joined logically together, comprise the module and achieve the stated purpose for the module.

Indeed, a module of executable code may be a single instruction, or many instructions, and may even be distributed over several different code segments, among different programs, and across several memory devices. Similarly, operational data may be identified and illustrated herein within modules, and may be embodied in any suitable form and organized within any suitable type of data structure. The operational data may be collected as a single data set, or may be distributed over different locations including over different storage devices, and may exist, at least partially, merely as electronic signals on a system or network. These modules may be passive or active, including agents operable to perform desired functions.

Reference in the specification to "an example" means that a particular feature, structure, or characteristic described in connection with the example is included in at least one embodiment of the invention. Thus, the appearances of the phrase "in an example" in various places throughout this application are not necessarily all referring to the same embodiment.

As used herein, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a general list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a general group without indications to the contrary. Moreover, various embodiments and examples of the present invention may be referred to herein along with their substitution of various components. It should be understood that such embodiments, examples, and alternatives are not to be construed as actual equivalents to each other, but are to be considered as independent and autonomous representations of the present invention.

Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided (e.g., examples of layouts, distances, network examples, etc.) to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, arrangements, and so forth. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.

While the above examples are illustrative of the principles of the present invention in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the assistance of the inventors and without departing from the principles and concepts of the invention. Accordingly, the invention is not intended to be limited, except as by the appended claims.

Claims (25)

1. A User Equipment (UE) operable to reduce signal interference, the UE comprising:

a communication module configured to:

receiving semi-static signaling from a neighboring evolved node B (eNB) via a serving eNB, the semi-static signaling including a potential configuration of signal parameters used at the neighboring eNB, the UE located within a cell served by the serving eNB; and

receiving dynamic signaling at the UE directly from the neighboring eNB, the dynamic signaling comprising a subset of potential configurations of the signal parameters used in a particular downlink subframe at the neighboring eNB, wherein the communication module is stored in a digital memory device or implemented in hardware circuitry; and

an interference reduction module configured to reduce signal interference caused by the neighboring eNB at the UE using the semi-static signaling comprising a potential configuration of the signal parameter and the dynamic signaling comprising a subset of the potential configuration of the signal parameter, wherein the interference reduction module is stored in a digital memory device or implemented in hardware circuitry.

2. The UE of claim 1, wherein the communication module is further configured to receive the dynamic signaling from the neighboring eNB via a Physical Downlink Control Channel (PDCCH) or an Enhanced PDCCH (EPDCCH).

3. The UE of claim 1, wherein the communication module is further configured to receive the semi-static signaling from the serving eNB via Radio Resource Control (RRC) signaling.

4. The UE of claim 1, wherein the communication module is further configured to receive the semi-static signaling from the neighboring eNB according to a predetermined periodicity.

5. The UE of claim 1, wherein the subset of potential configurations of signal parameters is an actual configuration of signal parameters used at the neighboring eNB.

6. The UE of claim 1, wherein the UE is located adjacent to a cell edge within the cell served by the serving eNB and experiences signal interference from the neighboring eNB.

7. The UE of claim 1, wherein the neighboring eNB is located within a neighboring cell proximate to the serving eNB serving the UE.

8. The UE of claim 1, wherein the communication module is further configured to: receiving the semi-static signaling from the serving eNB via a unicast transmission, wherein the serving eNB receives the semi-static signaling from the neighboring eNB via a backhaul link.

9. The UE of claim 1, wherein the subset of the potential configurations of the signal parameters in the semi-static signaling and the potential configurations of the signal parameters in the dynamic signaling comprises at least one of:

physical Resource Block (PRB) allocation granularity;

a subset of supported transmission modes;

an indication to use PRB hopping at the neighboring eNB;

a maximum number of layers for downlink transmission;

a maximum modulation order;

an uplink-downlink configuration of the frame;

a subset of power offset values; or

A subset of scrambling identities for UE-specific reference signals for the defined transmission mode.

10. The UE of claim 1, wherein the interference reduction module is further configured to: performing blind detection to reduce signal interference caused by the neighboring eNB, wherein the UE performs the blind detection using at least one of a potential configuration of the signal parameters in the semi-static signaling or a subset of potential configurations of the signal parameters in the dynamic signaling.

11. The UE of claim 1, wherein the communication module is further configured to: receiving the dynamic signaling from the neighboring eNB in response to the neighboring eNB selecting at least one of a potential configuration of the signal parameters or modifying signal parameters in an existing configuration.

12. The UE of claim 1, wherein the communication module is further configured to receive the dynamic signaling from the neighboring eNB via a broadcast transmission.

13. A neighboring evolved node B (eNB) operable to assist in reducing signal interference, the neighboring eNB having one or more processors configured to:

transmitting semi-static signaling via a serving eNB to a User Equipment (UE), the semi-static signaling comprising a potential configuration of signal parameters used at the neighboring eNB, the UE located within a cell served by the serving eNB; and

transmitting dynamic signaling to the UE, the dynamic signaling comprising a subset of potential configurations of the signal parameters used by the neighboring eNB in a particular downlink subframe,

wherein the semi-static signaling comprising the potential configuration of the signal parameters and the dynamic signaling comprising a subset of the potential configuration of the signal parameters enable the UE to reduce signal interference caused by the neighboring eNB at the UE.

14. The neighboring eNB of claim 13, wherein the one or more processors are further configured to transmit the semi-static signaling to the UE according to a defined periodicity.

15. The neighboring eNB of claim 13, wherein the one or more processors are further configured to: sending the dynamic signaling to the UE in response to selecting at least one of the potential configurations of the signal parameters or modifying signal parameters in an existing configuration.

16. The neighboring eNB of claim 13, wherein the UE that is experiencing signal interference from the neighboring eNB is located adjacent to a cell edge within the cell served by the serving eNB.

17. The neighboring eNB of claim 13, wherein the neighboring eNB is located within a neighboring cell proximate to the serving eNB serving the UE.

18. The neighboring eNB of claim 13, wherein the one or more processors are further configured to: sending the semi-static signaling to the serving eNB over a backhaul link, wherein the serving eNB forwards the semi-static signaling to the UE via a unicast transmission.

19. The neighboring eNB of claim 13, wherein the subset of the potential configurations of the signal parameters in the semi-static signaling and the potential configurations of the signal parameters in the dynamic signaling comprises at least one of:

physical Resource Block (PRB) allocation granularity;

a subset of supported transmission modes;

an indication to use PRB hopping at the neighboring eNB;

a maximum number of layers for downlink transmission;

a maximum modulation order;

an uplink-downlink configuration of the frame;

a subset of power offset values; or

A subset of scrambling identities for UE-specific reference signals for the defined transmission mode.

20. The neighboring eNB of claim 13, wherein the one or more processors are further configured to: sending the dynamic signaling to the UE via broadcast transmission.

21. A method for reducing signal interference, the method comprising:

receiving semi-static signaling at a User Equipment (UE) from a neighboring evolved node B (eNB), the semi-static signaling including a potential configuration of signal parameters used at the neighboring eNB;

receiving, at the UE, dynamic signaling from the neighboring eNB, the dynamic signaling comprising a subset of potential configurations of the signal parameters used at the neighboring eNB; and

using the semi-static signaling and the dynamic signaling to reduce signal interference at the UE caused by the neighboring eNB.

22. The method of claim 21, further comprising: performing blind detection using the semi-static signaling and the dynamic signaling to reduce signal interference caused by the neighboring eNB.

23. The method of claim 21, wherein the subset of potential configurations of signal parameters is an actual configuration of signal parameters used at the neighboring eNB.

24. The method of claim 21, further comprising: receiving the semi-static signaling from the neighboring eNB via a unicast transmission, wherein the serving eNB receives the semi-static signaling from the neighboring eNB via a backhaul link, and wherein the UE is located within a cell served by the serving eNB.

25. The method of claim 21, further comprising:

receiving the semi-static signaling from the neighboring eNB according to a defined periodicity; and

receiving the dynamic signaling from the neighboring eNB in response to the neighboring eNB selecting at least one of a potential configuration of the signal parameters or modifying signal parameters in an existing configuration.