HK1179067B - Cqi estimation in a wireless communication network - Google Patents

Description

CQI estimation in a wireless communication network

The present application claims priority from us provisional application S/n.61/323,822 entitled "CQI estimation in wireless communication NETWORKS" filed on 13.4.2010 and us provisional application S/n.61/323,770 entitled "method and apparatus for downlink power control in Long Term Evolution (LTE) NETWORKS" filed on 13.4.2010.

Background

FIELD

The present disclosure relates generally to communication, and more specifically to techniques for estimating Channel Quality Indicator (CQI) in a wireless communication network.

Background

Wireless communication networks are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These wireless networks may be multiple-access networks capable of supporting multiple users by sharing the available network resources. Examples of such multiple-access networks include Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, Frequency Division Multiple Access (FDMA) networks, orthogonal FDMA (ofdma) networks, and single carrier FDMA (SC-FDMA) networks.

A wireless communication network may include a number of base stations capable of supporting communication for a number of User Equipments (UEs). The base station may transmit data to the UE. Good performance may be achieved by having the UE estimate the quality of the communication channel from the base station to the UE, determine a CQI based on the estimated channel quality, and send the CQI to the base station. The CQI may indicate an estimated channel quality or a modulation and coding scheme that may be used for data transmission over the communication channel. It may be desirable to accurately estimate and report the CQI so that good performance can be achieved for data transmission.

SUMMARY

Techniques for estimating and reporting CQI are described herein. Neighboring base stations may cause strong interference to each other and may be allocated different resources, e.g., different subframes. The resources allocated to each base station may have reduced or no interference from other base stations. Resources not allocated to each base station may have strong interference from other base stations. UEs communicating with a base station may observe different levels/amounts of interference on different resources.

In an aspect, a UE may determine a CQI for resources allocated to a base station and having reduced or no interference from at least one interfering base station. In one design, a UE may receive signaling conveying resources (e.g., subframes) allocated to a base station. The UE may determine at least one resource allocated to the base station based on the received signaling. The UE may determine a CQI based on the at least one resource allocated to the base station and may exclude resources allocated to the at least one interfering base station. The UE may send a CQI to the base station and may subsequently receive a data transmission sent by the base station based on the CQI.

In another aspect, the UE may determine multiple CQIs for resources of different types and associated with different levels of interference. In one design, a UE may receive resource partitioning information that conveys subframes semi-statically allocated to a base station and subframes semi-statically allocated to at least one interfering base station. The UE may determine at least one first subframe allocated to the base station and at least one second subframe allocated to the at least one interfering base station based on the resource partitioning information. The at least one first subframe may have reduced or no interference from the at least one interfering base station. The UE may determine a first CQI based on the at least one first subframe and may determine a second CQI based on the at least one second subframe. The UE may send the first CQI and the second CQI to the base station. The UE may then receive a data transmission sent by the base station based on the first CQI and/or the second CQI.

The base station may perform complementary functions to support CQI estimation and reporting by the UE, as described below. Various aspects and features of the disclosure are described in greater detail below.

Brief description of the drawings

Fig. 1 illustrates a wireless communication network.

Fig. 2 shows an exemplary frame structure.

Fig. 3 shows two exemplary subframe formats.

Fig. 4 illustrates an exemplary interleaving structure.

Fig. 5 shows an example of resource partitioning for two base stations.

Fig. 6 illustrates a process for determining a clean CQI for an allocated resource.

Fig. 7 illustrates a process for receiving a clean CQI for an allocated resource.

Fig. 8 illustrates a process for determining multiple CQIs for different resources.

Fig. 9 shows a process for receiving multiple CQIs for different resources.

Fig. 10 shows a process for transmitting data.

FIG. 11 shows a block diagram of a design of a base station and a UE.

FIG. 12 shows a block diagram of another design of a base station and a UE.

Detailed Description

The techniques described herein may be used for various wireless communication networks such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA and other networks. The terms "network" and "system" are often used interchangeably. CDMA networks may implement methods such as Universal Terrestrial Radio Access (UTRA), CDMA2000, etc. radio technologies. UTRA includes wideband CDMA (wcdma), time division synchronous CDMA (TD-SCDMA), and other CDMA variants. cdma2000 covers IS-2000, IS-95 and IS-856 standards. TDMA networks may implement radio technologies such as global system for mobile communications (GSM). OFDMA networks may implement methods such as evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE802.11(Wi-Fi), IEEE802.16(WiMAX), IEEE802.20, and,And so on. UTRA and E-UTRA are parts of the Universal Mobile Telecommunications System (UMTS). The 3GPP Long Term Evolution (LTE) and LTE-advanced (LTE-a) in both Frequency Division Duplex (FDD) and Time Division Duplex (TDD) forms are new versions of UMTS that use E-UTRA, employing OFDMA on the downlink and SC-FDMA on the uplink. UTRA, E-UTRA, UMTS, LTE-A and GSM are described in literature from an organization named "3 rd Generation partnership project" (3 GPP). cdma2000 and UMB are described in documents from an organization named "3 rd generation partnership project 2" (3GPP 2). The techniques described herein may be used for the above-mentioned wireless networks and radio technologies as well as other wireless networks and radio technologies. For clarity, certain aspects of the techniques are described below for LTE, and LTE terminology is used in much of the description below.

Fig. 1 shows a wireless communication network 100, which may be an LTE network or some other wireless network. Wireless network 100 may include several evolved node bs (enbs) and other network entities. An eNB may be an entity in communication with a UE and may also be referred to as a base station, a node B, an access point, etc. Each eNB may provide communication coverage for a particular geographic area and may support communication for UEs located within that coverage area. To improve network capacity, the overall coverage area of an eNB may be divided into multiple (e.g., three) smaller areas. Each smaller area may be served by a respective eNB subsystem. In 3GPP, the term "cell" can refer to a coverage area of an eNB and/or an eNB subsystem serving this coverage area. In general, an eNB may support one or more (e.g., three) cells.

An eNB may provide communication coverage for a macro cell, a pico cell, a femto cell, and/or other types of cells. A macro cell may cover a relatively large geographic area (e.g., an area with a radius of several kilometers) and may allow unrestricted access by UEs with service subscriptions. Picocells may cover a relatively small geographic area and may allow unrestricted access by UEs with service subscriptions. A femtocell may cover a relatively small geographic area (e.g., a residence) and may be restrictively accessible by UEs associated with the femtocell (e.g., UEs in a Closed Subscriber Group (CSG)). The eNB of a macro cell may be referred to as a macro eNB. An eNB for a picocell may be referred to as a pico eNB. An eNB for a femtocell may be referred to as a home eNB (henb). In the example shown in fig. 1, eNB110a may be a macro eNB for macro cell 102a, eNB110b may be a pico eNB for pico cell 102b, and eNB110c may be a home eNB for femto cell 102 c. The terms "eNB" and "base station" are used interchangeably herein.

Wireless network 100 may also include relays. A relay may be an entity that can receive a transmission of data from an upstream station (e.g., an eNB or UE) and send a transmission of the data to a downstream station (e.g., a UE or eNB). The relay may also be a UE that can relay transmissions for other UEs. In the example shown in fig. 1, relay 110d may communicate with macro eNB110a and UE120d to facilitate communication between eNB110a and UE120 d. A relay may also be referred to as a relay station, relay eNB, relay base station, etc.

Wireless network 100 may be a heterogeneous network (HetNet) including different types of enbs, e.g., macro eNB, pico eNB, home eNB, relay, etc. These different types of enbs may have different transmit power levels, different coverage areas, and different effects on interference in wireless network 100. For example, macro enbs may have a higher transmit power level (e.g., 5 to 40 watts), while pico enbs, henbs, and relays may have a lower transmit power level (e.g., 0.1 to 2 watts).

Network controller 130 may be coupled to a set of enbs and may provide coordination and control for these enbs. Network controller 130 may communicate with the enbs via a backhaul. The enbs may also communicate with each other, directly or indirectly, e.g., via a wireless or wired backhaul.

UEs 120 may be dispersed throughout wireless network 100, and each UE may be stationary or mobile. A UE may also be referred to as a mobile station, terminal, access terminal, subscriber unit, station, etc. A UE may be a cellular phone, a Personal Digital Assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a Wireless Local Loop (WLL) station, a smart phone, a netbook, a smartbook, a tablet, and so forth. The UE may communicate with the eNB via the downlink and uplink. The downlink (or forward link) refers to the communication link from the eNB to the UE, and the uplink (or reverse link) refers to the communication link from the UE to the eNB node. In fig. 1, a solid line with double arrows indicates the desired transmission between a UE and a serving eNB, which is an eNB designated to serve the UE on the downlink and/or uplink. The dashed line with double arrows indicates interfering transmissions between the UE and the eNB.

Fig. 2 shows an exemplary frame structure 200 for FDD in LTE. The transmission timeline for each of the downlink and uplink may be partitioned into units of radio frames. Each radio frame may have a predetermined duration, e.g., 10 milliseconds (ms), and may be divided into 10 subframes with indices of 0 through 9. Each subframe may include two slots. Each radio frame may thus comprise 20 time slots with indices 0 to 19. Each slot may include L symbol periods, e.g., 7 symbol periods for a normal cyclic prefix (as shown in fig. 2) or 6 symbol periods for an extended cyclic prefix. The 2L symbol periods in each subframe may be assigned indices 0 through 2L-1.

LTE utilizes Orthogonal Frequency Division Multiplexing (OFDM) on the downlink and single carrier frequency division multiplexing (SC-FDM) on the uplink. OFDM and SC-FDM divide a frequency range into multiple (N)_FFTMultiple) orthogonal subcarriers, which are also often referred to as tones, bins, etc. Each subcarrier may be modulated with data. Generally, modulation codesThe bins are sent in the frequency domain under OFDM and in the time domain under SC-FDM. The spacing between adjacent subcarriers may be fixed, and the total number of subcarriers (N)_FFT) May depend on the system bandwidth. For example, the subcarrier spacing may be 15 kilohertz (KHz), and N_FFTThe system bandwidth may be equal to 128, 256, 512, 1024 or 2048 for 1.25, 2.5, 5, 10 or 20 megahertz (MHz), respectively. The system bandwidth may also be divided into sub-bands. Each sub-band may cover a frequency range, e.g., 1.08MHz or some other range.

The time-frequency resources available for each of the downlink and uplink may be divided into resource blocks. The number of resource blocks available in a slot per link may depend on the system bandwidth and may range from 6 to 110 for system bandwidths of 1.25 to 20MHz, respectively. Each resource block may cover 12 subcarriers in one slot and may include several resource elements. Each resource element may cover one subcarrier in one symbol period and may be used to transmit one modulation symbol, which may be a real or complex value.

In LET, an eNB may transmit Primary Synchronization Signals (PSS) and Secondary Synchronization Signals (SSS) on the downlink in the central 1.08MHz of the system bandwidth for each cell supported by the eNB. The PSS and SSS may be transmitted in symbol periods 6 and 5, respectively, in subframes 0 and 5 of each radio frame with the normal cyclic prefix, as shown in fig. 2. The PSS and SSS may be used by the UE for cell search and acquisition. An eNB may transmit cell-specific reference signals (CRSs) across a system bandwidth for each cell supported by the eNB. The CRS may be transmitted in certain symbol periods of each subframe and may be used by UEs to perform channel estimation, channel quality measurement, and/or other functions. The eNB may also transmit a Physical Broadcast Channel (PBCH) in symbol periods 0 to 3 in slot 1 of certain radio frames. The PBCH may carry some system information. The eNB may transmit other system information such as System Information Blocks (SIBs) on a Physical Downlink Shared Channel (PDSCH) in certain subframes.

FIG. 3 shows the operation with normal circulation beforeTwo exemplary subframe formats 310 and 320 for the downlink are interspersed. Subframe format 310 may be used by an eNB equipped with two antennas. The CRS may be transmitted from antennas 0 and 1 in symbol periods 0, 4, 7, and 11. The reference signal is a signal known a priori by both the transmitter and the receiver and may also be referred to as a pilot. A CRS is a cell-specific reference signal, e.g., generated based on a cell Identity (ID). In FIG. 3, for a reference R_aMay transmit modulation symbols from antenna a on the resource element, and may not transmit modulation symbols from other antennas on the resource element. Subframe format 320 may be used by an eNB equipped with four antennas. The CRS may be transmitted from antennas 0 and 1 in symbol periods 0, 4, 7, and 11 and from antennas 2 and 3 in symbol periods 1 and 8. For both subframe formats 310 and 320, CRS may be transmitted on evenly spaced subcarriers, which may be determined based on the cell ID. Different enbs may transmit their CRSs on the same or different subcarriers depending on their cell IDs. For both subframe formats 310 and 320, resource elements not used for CRS may be used to transmit data (e.g., traffic data, control data, and/or other data).

PSS, SSS, CRS and PBCH in LTE are publicly available under the heading "evolvedUniversal TerriesterRadioaccess (E-UTRA); physical channels and modulation is described in 3gpp ts36.211 of evolved universal terrestrial radio access (E-UTRA); physical channel and modulation).

Fig. 4 shows an exemplary interleaving structure 400 that may be used for each of the downlink and uplink for FDD in LTE. As shown in FIG. 4, Q interlaces may be defined with indices of 0 through Q-1, where Q may equal 6, 8, 10, or some other value. Each interlace may include subframes that are spaced Q subframes apart. Specifically, interlace Q may include subframe Q, Q + Q, Q +2Q, etc., where Q ∈ { 0., Q-1 }.

A wireless network may support data transmission with hybrid automatic repeat request (HARQ) on the downlink and/or uplink. For HARQ, a transmitter (e.g., an eNB) may send an initial transmission of a data packet and may then send one or more additional transmissions of the packet, if needed, until the packet is decoded correctly by a receiver (e.g., a UE), or a maximum number of transmissions have been sent, or some other termination condition is encountered. After each transmission of a packet, the receiver may decode all received transmissions of the packet in an attempt to recover the packet. The receiver may send an Acknowledgement (ACK) if the packet is decoded correctly or a Negative Acknowledgement (NACK) if the packet is decoded in error. The transmitter may send another transmission of the packet if a NACK is received and may terminate transmission of the packet if an ACK is received. The transmitter may process (e.g., encode and modulate) the packet based on a Modulation and Coding Scheme (MCS) that may be selected to enable correct decoding of the packet with a high probability after a target number of transmissions of the packet. This target number of transmissions may be referred to as HARQ target termination.

For synchronous HARQ, all transmissions of a packet may be sent in subframes of a single interlace. For asynchronous HARQ, each transmission of a packet may be sent in any subframe.

The UE may be located within the coverage of multiple enbs. One of the enbs may be selected to serve the UE. The serving eNB may be selected based on various criteria such as received signal strength, received signal quality, path loss, and so on. The received signal quality may be quantified by a signal-to-noise-and-interference ratio (SINR), a carrier-to-interference ratio (C/I), a Reference Signal Received Quality (RSRQ), and the like. For clarity, SINR is used in much of the description below to represent received signal quality.

The UE may operate in a dominant interference scenario where the UE may observe strong interference from one or more interfering enbs. A strong interference scenario may occur due to constrained association. For example, in fig. 1, the UE120c may be close to the HeNB110c and may have high received power to the eNB110 c. However, the UE120c may not be able to access the HeNB110c due to the restricted association and may then connect to the macro eNB110a with lower received power. UE120c may then observe strong interference from HeNB110c on the downlink and may also cause strong interference to HeNB110c on the uplink.

A dominant interference scenario may also occur due to range extension, which is a scenario in which the UE is connected to an eNB with lower path loss and possibly lower SINR among all enbs detected by the UE. For example, in fig. 1, UE120b may be closer to pico eNB110b than macro eNB110a and may have a lower path loss for pico eNB110 b. However, because pico eNB110b has a lower transmit power level than macro eNB110a, UE120b may have a lower received power for pico eNB110b than macro eNB110 a. However, due to lower path loss, it may be desirable for UE120b to connect to pico eNB110 b. This results in less interference to the wireless network for a given data rate for UE120 b.

Communication in a dominant interference scenario may be supported by performing inter-cell interference coordination (ICIC). In one design of ICIC, resource partitioning/coordination may be performed to allocate resources to enbs located near the vicinity of the strong interfering enbs. The interfering eNB may refrain from transmitting or transmit at a lower power level (possibly except for CRS) on the allocated resources. In the presence of the interfering eNB, the UE may then reliably communicate with the eNB on the allocated resources, and may observe reduced interference or no interference from the interfering eNB (possibly except for CRS). For example, in fig. 1, some resources may be allocated to pico eNB110b and may have reduced or no interference from interfering macro eNB110 a. Pico eNB110b may then reliably communicate with UE120b on the allocated resources.

In general, time and/or frequency resources may be allocated to an eNB via resource partitioning. In one design, the system bandwidth may be divided into a number of subbands, and one or more subbands may be allocated to an eNB. In another design, a set of subframes may be allocated to an eNB. In yet another design, a set of resource blocks may be allocated to an eNB. For clarity, much of the description below assumes a Time Division Multiplexing (TDM) resource partitioning scheme in which one or more interlaces may be allocated to an eNB. Subframes of the allocated interlace may observe reduced or no interference from a strong interfering eNB. TDM resource partitioning may be particularly applicable to co-channel deployments in which macro enbs and other types of enbs operate on the same frequency channel.

In general, resource partitioning can be performed by a set of enbs (e.g., through negotiation via a backhaul) or by a designated network entity (e.g., network controller 130 in fig. 1) for the set of enbs. In one design, each eNB may be allocated some resources (e.g., some subframes) that may be used by the eNB and that have reduced or no interference from other enbs in the group. In one design, resource partitioning may be performed in a semi-static manner. In another design, resource partitioning may be performed in a semi-static and dynamic/adaptive manner. For example, some minimum resources (e.g., a minimum number of subframes) may be semi-statically allocated to an eNB, and additional resources (e.g., additional subframes) may be dynamically or adaptively allocated to the eNB. The semi-statically allocated resources may ensure that each eNB has sufficient resources to reliably transmit control data to support communication with its UEs. The dynamically allocated resources may depend on the traffic load of different enbs and may be used to transmit traffic data and/or other data. For clarity, much of the description below assumes semi-static and dynamic resource allocation.

Fig. 5 shows an example of TDM resource partitioning for supporting communication in a dominant interference scenario involving two enbys and Z. In this example, interlace 0 may be allocated to eNBY and interlace 7 may be allocated to eNBZ in a semi-static manner, e.g., via negotiation between enbs over the backhaul. eNBY may transmit in subframes of interlace 0 and may avoid transmitting in subframes of interlace 7 or may transmit at lower power in subframes of interlace 7. Conversely, eNBZ may be transmitted in subframes of interlace 7 and may avoid transmitting in subframes of interlace 0 or may transmit at lower power in subframes of interlace 0. The subframes of the remaining interlaces 1 to 6 may be dynamically/adaptively allocated to eNBY and/or eNBZ.

Table 1 lists different types of subframes according to one design. From the perspective of eNBY, the interlace allocated to eNBY may include "protected" subframes (denoted as U subframes) that can be used by eNBY and have reduced or no interference from interfering enbs. The interlace allocated to another eNBZ may include "prohibited" subframes (denoted as N subframes) that cannot be used by eNBY or that can be used at lower transmit power levels. The interlaces not allocated to any eNB may include "common" subframes (denoted as C subframes) that can be used by different enbs. The dynamically allocated subframes are labeled with AN "a" prefix and may be protected subframes (noted AU subframes), or prohibited subframes (noted AN subframes), or common subframes (noted AC subframes). These different types of subframes may also be referred to by other names. For example, protected subframes may be referred to as reserved subframes, allocated subframes, and the like.

TABLE 1 subframe types

In one design, an eNB may transmit (e.g., broadcast) Static Resource Partitioning Information (SRPI) to its UEs. In one design, the SRPI may include Q fields for Q-strand interlaces. In one design, the field for each interlace may be set to (i) U to indicate that the interlace is allocated to the eNB and includes U subframes, or (ii) N to indicate that the interlace is allocated to another eNB and includes N subframes, or (iii) X to indicate that the interlace is dynamically allocated to any eNB and includes X subframes. The X subframe may be AN AU subframe allocated to AN eNB, AN subframe allocated to another eNB, or AN AC subframe usable by a different eNB.

The UE may receive an SRPI from an eNB and identify U and N subframes with respect to the eNB based on the SRPI. For each interlace labeled "X" in the SRPI, the UE may not know whether the X subframes in that interlace will be AU subframes, AN subframes, or AC subframes. The UE may have only partial knowledge of the resource partitioning and may only know the semi-static part of the resource partitioning via SRPI. The eNB may have full knowledge of the resource partitioning and may know both the semi-static and dynamic portions of the resource partitioning.

The UE may estimate the SINR of the eNB based on the CRS received from the eNB. The UE may determine a CQI based on the estimated SINR and may report the CQI to the eNB. The eNB may use the CQI for link adaptation to select a Modulation and Coding Scheme (MCS) for data transmission to the UE. Different types of subframes may have different interference levels and may therefore be associated with very different CQIs. In particular, protected subframes (e.g., U and AU subframes) may be characterized by better CQI because the dominant interfering eNB does not transmit or transmits at a lower power level in these subframes. Conversely, the CQI may be much worse for other subframes (e.g., N, AN, C, and AC subframes) in which one or more dominant interfering enbs may transmit at a higher power level. From a CQI perspective, AN AU subframe may be equivalent to a U subframe (since both are protected subframes) and AN subframe may be equivalent to AN N subframe (since both are prohibited subframes). The AC subframes may be different from the U and AU subframes and also different from the N and AN subframes. Thus, the AC sub-frame may be characterized by a CQI that is completely different from the CQIs of the U and AU sub-frames and the CQIs of the N and AN sub-frames. To achieve good link adaptation performance, the eNB should have a relatively accurate CQI for each subframe in which the eNB can transmit data to the UE.

In an aspect, a UE may determine a CQI for protected subframes with reduced or no interference from an interfering eNB. The protected subframes may be selected first by the eNB for data transmission to the UE because the CQI for these subframes is likely to be higher due to being protected from the interfering eNB. The CQI for one or more protected subframes may be referred to as a "clean" CQI to emphasize that the CQI is measured over subframes in which the dominant interfering eNB is not transmitting or transmitting at a lower power level.

In another aspect, the UE may determine multiple CQIs for different types of subframes that may observe different levels of interference and may therefore be associated with different CQIs. In one design, a clean CQI may be obtained for one or more protected subframes and at least one additional CQI may be obtained for at least one reference subframe. The reference subframe is a subframe for determining/estimating additional CQI. The reference subframe may be a subframe that is not a protected subframe and may be AN N, AN, C, or AC subframe. The CQI for one or more reference subframes may be referred to as an "unclean" CQI to emphasize that the CQI is measured over one or more subframes in which one or more interfering enbs may transmit at a higher power level.

In one design, several CQI modes may be supported, and the UE may determine one or more CQIs in each CQI mode. Table 2 lists three CQI modes that may be supported according to one design.

TABLE 2 CQI modes

CQI mode 1 may be compatible with CQI modes that do not support unclean CQI. However, clean CQI alone may not be sufficient for the eNB scheduler, especially if there is a large amount of traffic data on the downlink and all traffic data cannot be scheduled in U subframes. If the eNB schedules UEs on AC subframes, the clean CQI may be too optimistic because the AC subframes are unprotected and the performance of data transmission in these AC subframes may be poor. CQI mode 2 may be used to determine and report both clean CQI and unclean CQI. CQI mode 3 may be used to determine and report a clean CQI and a plurality of unclean CQIs. The number of unclean CQIs to be reported may be selected based on a trade-off between the signaling overhead for reporting unclean CQIs and the improvement of data transmission performance with multiple unclean CQIs. CQI modes 2 and 3 may provide the eNB more flexibility to schedule UEs on a protected subframe or some other subframe and still achieve good performance for data transmission. For CQI modes 2 and 3, the combination of clean and unclean CQI may be referred to as vector CQI.

Unclean CQI may be determined with respect to one or more reference subframes, which may be selected in various ways. In one design, subframes used to determine unclean CQI may be selected by the UE. The UE may select one or more reference subframes for determining unclean CQI based on its limited knowledge only of the location of the U and N subframes of the eNB. In another design, subframes used to determine unclean CQI may be selected by the eNB and signaled to the UE.

In a first design, the unclean CQI may be determined based on only one or more N subframes (but not other types of subframes). The N subframes for determining unclean CQI may be selected in various ways. In one design, the N subframes may be configured by the eNB and signaled to the UE. For example, the UE may be configured to determine an unclean CQI for each pth subframe in one or more interlaces containing N subframes, where P may be any value. In another design, the UE may be configured to determine an unclean CQI for N subframes as close as possible to the subframe in which the CQI report is transmitted by the UE. For example, the UE may send a CQI report in subframe N, and the N subframes used to determine unclean CQI may be subframe N-m, where m may be equal to or greater than m_minIs the smallest integer of (i.e., m.gtoreq.m)_min) Such that subframes N-m are N subframes. m is_minMay be the minimum delay between CQI estimation and reporting and may be equal to 4 or some other value. The N subframes used to determine unclean CQI may also be selected in other manners. The UE may not be scheduled for data transmission in the N subframes, which may be protected subframes of another eNB. The unclean CQI determined based on N subframes may represent a worst case CQI for the UE.

In a second design, the unclean CQI may be determined by averaging over a set of subframes that may not include U subframes. In one design, the set of subframes may be configured by the eNB and signaled to the UE. For the example shown in fig. 5, the UE may be configured to determine unclean CQIs for subframes 1 through 7. In another design, the set of subframes may depend on when a CQI report is sent by the UE. For example, the UE may send a CQI report in subframe n and be used to determine not toThe set of subframes for the clean CQI may include subframes n-k (where k is_min≤k≤k_max) But does not include any U subframes. In one design, k_minAnd/or k_maxMay be a fixed value, for example as specified in the standard. E.g. k_minMay be equal to a fixed value of 4 or some other value. As another example, k_max-k_minMay be equal to a fixed value of 8 or some other value. In another design, k_minAnd/or k_maxMay be determined by the UE based on resource partitioning and/or other information. E.g. k_minMay be equal to a fixed value of 4, and k_maxMay be determined based on the number of interlaces Q (e.g., k)_max＝k_min+ Q-1). For the example of Q-8 shown in fig. 5, the subframe set may include up to 8 non-U subframes that are 4 to 11 subframes earlier than subframe n. In another design, k_minAnd/or k_maxMay be configured by the eNB and signaled to the UE. For all designs, the UE may estimate the SINR for each subframe in the set of subframes. The UE may then average the SINRs for all subframes in the set to obtain an average SINR. The UE may then determine an unclean CQI based on the average SINR.

In a third design, the unclean CQI may be determined by averaging over a set of subframes that may not include N and U subframes. In one design, the set of subframes may be configured by the eNB and signaled to the UE. In another design, the set of subframes may depend on when a CQI report is sent by the UE. For example, the UE may send a CQI report in subframe n, and the set of subframes used to determine unclean CQI may include subframe n-k (where k is_min≤k≤k_max) But does not include any U subframes and any N subframes.

In a fourth design, the unclean CQI may be determined by separately estimating interference in the N and U subframes and estimating the total interference observed by the UE. The U subframes may not include interference from a dominant interfering eNB (except possibly CRS), but may include interference from other enbs. The N subframes may include interference from interfering enbs that are allocated the subframes, but may not include interference from other enbs. For example, subframes may be allocated to enbs of different power classes, U subframes may be allocated to macro enbs, and N subframes may be allocated to pico and/or home enbs. The UE may communicate with the macro eNB and may observe interference from other macro enbs at the same power level in the U subframes. The UE may observe interference from pico and home enbs in the N subframes.

Thus, the UE may observe interference from different interfering enbs in different subframes, and neither U or N subframes may capture the total interference observed by the UE. The eNB may wish to know the total (worst case) interference observed by the UE. In this case, the UE may estimate interference in N subframes and U subframes separately. The UE may then combine the estimated interference for the N subframes and the estimated interference for the U subframes based on a suitable combining function to obtain the total interference. The combining function should avoid counting interference repeatedly from any given interfering eNB. For example, if an interfering eNB transmits in both N and U subframes, the estimated interference from either the N or U subframes (rather than both subframes at the same time) for this interfering eNB may be used to calculate the total interference.

The UE may estimate interference for each interfering eNB based on the CRSs transmitted by that eNB. Depending on the cell IDs of different enbs, CRSs from these enbs may or may not collide. The UE may perform Reference Signal Interference Cancellation (RSIC) if CRSs from different enbs collide. For example, if CRS from eNBY and Z collide, the UE may estimate and cancel interference due to CRS from eNBY before measuring CRS from eNBZ, and vice versa. More accurate measurements of CRS from an eNB may be obtained by canceling interference due to CRS from other enbs. Interference caused by a given eNB in a given subframe may be estimated based on received power of CRSs from the eNB in the subframe (possibly after estimating and cancelling CRSs from other enbs in the subframe).

The total interference may be determined based on estimated interference for different types of subframes, including U and N subframes. The combining function may be designed to provide an accurate estimate of the total interference based on the estimated interference for the U subframes, the estimated interference for the N subframes, and the estimated interference for the other subframes. The UE may determine an unclean CQI based on the total interference.

In a fifth design, an unclean CQI may be determined for one or more reference subframes selected in a predetermined manner. In one design, different subframes may be selected in a manner to determine unclean CQI by cycling through different offsets and selecting one or more subframes in each CQI reporting period. For example, the UE may send a CQI report in subframe n, and subframes n-m_min-k_iCan be used to determine unclean CQI, where k_iDenotes the subframe offset of the reporting period i and m_minIs a fixed delay (e.g., m)_min＝4)。

The reporting index i may range from 0 to K-1, where K may represent the number of offsets and may be any value. The index i may be initialized to 0 after a successful access procedure, or after an cqi-pmi-configIndex update from the upper layers, or based on some other event. The index i may be incremented by 1 after each CQI report, e.g., i ═ i +1) modK.

Number of offsets (K) and/or K offsets (K) for K reporting periods (0 to K-1)₀To k_K-1) May be determined in various ways, respectively. In one design, the number of offsets and/or the K offsets may be fixed values. For example, the number of offsets may be equal to a fixed value of 2, 4, or some other value, and the K offsets may include offsets 0 through K-1. In another design, the number of offsets and/or the K offsets may depend on the resource partitioning. For example, the number of offsets may be equal to the number of interlaces (or K — Q), and Q offsets may include 0 to Q-1. In a further embodiment, the number of offsets (K) and/or K offsets K₀To k_K-1May be configured by the eNB and signaled to the UE.

For the fifth design, the unclean CQI reported in subframe n may be based on a single subframe n-m_min-k_iAs described above. Unclean CQI may also be based on multiple subframes (e.g., subframe n-m)_min-k_iTo sub-frame n-m_min-k_i-S +1), where S is to beThe unclean CQI is taken as the number of subframes averaged. For both cases, multiple unclean CQIs may be efficiently determined and reported by cycling through different offsets in a manner that selects different subframes in which to determine the unclean CQI.

Five exemplary designs for selecting one or more reference subframes for determining unclean CQI have been described above. Unclean CQI may also be determined with respect to one or more reference subframes that may be otherwise selected.

The UE may select a reference subframe for determining a plurality of unclean CQIs in various manners. In a first design, one unclean CQI may be determined for one or more N subframes and another unclean CQI may be determined for one or more X subframes. In a second design, multiple unclean CQIs may be determined for multiple subframes with different offsets. The subframes used to determine the plurality of unclean CQIs may also be determined in other manners.

The eNB may select a reference subframe for determining unclean CQI and may signal the selected subframe to the UE. In one design, one or more reference subframes used to determine unclean CQI may have a fixed offset relative to one or more subframes used to determine clean CQI. In another design, one or more reference subframes used to determine unclean CQI may have a fixed offset from subframes used for CQI reporting. For example, the UE may send a CQI report in subframe n, and the reference subframe for determining unclean CQI may be subframe n-k_iWherein k is_iMay be a fixed offset. For both designs, the offset may be determined by the eNB and signaled to the UE, e.g., via a new cqi-pmi-configIndex configuration or a new field of an applicable Radio Resource Control (RRC) message. The eNB may change the offset (e.g., from time to time) and may send the new offset to the UE. The eNB may also select reference subframes for determining unclean CQI in other manners.

For the offset-based design described above, the offset may be determined differently for FDD and TDD. For FDD (e.g., as shown in fig. 2 and 5), all 10 subframes of a radio frame may be used for downlink, and the offset may be determined in a straightforward manner. For TDD, only some of the 10 subframes of each radio frame may be used for downlink, and the offset may account for valid subframes for downlink. For example, offset 3 in TDD may represent 3 valid subframes for downlink before the subframe used to determine clean CQI or unclean CQI.

The clean and unclean CQIs may be determined and reported at any periodicity. In one design, the clean and unclean CQIs may be determined and reported with the same periodicity (e.g., in the same subframe or different subframes). In another design, the clean and unclean CQIs may be determined and reported at different periodicities. For example, a clean CQI may be determined and reported more frequently than an unclean CQI. In one design, periodic Q or an integer multiple of Q may be used for the clean CQI. Any periodicity of values other than integer multiples of Q may implicitly be unclean CQI cycles for each subframe. For example, if Q is 8 as shown in fig. 5, a periodicity of 9 may cycle all subframes in different reporting periods. In one design, the same or different periodicities for clean and unclean CQIs may be configured for and signaled to the UE by the eNB.

In one design, the same CQI configuration may be used for both clean and unclean CQIs. In another design, different CQI configurations may be used for clean and unclean CQIs. The CQI configuration may be associated with various parameters for estimating and/or reporting CQI. For example, the CQI configuration may indicate a periodicity at which CQI is reported, a particular subframe in which CQI is reported, a particular offset determined for one or more subframes used to estimate CQI, and/or the like.

The eNB may maintain a set point for data (e.g., traffic data and/or control data) transmission on the downlink to the UE. The set point may correspond to a target SINR for the data transmission. The set point may be adjusted based on a power control loop (which may be referred to as an outer loop) to achieve a desired level of performance for data transmission. The desired performance level may be quantified by a target error rate, a target erasure rate, or some other metric. For example, the setpoint may be increased to a higher target SINR (i) if the performance is worse than the target error rate, or decreased to a lower target SINR (ii) if the performance is better than the target error rate. The set point and the estimated SINR may be used to determine a transmit power level for the data transmission. For example, if a transmit power level of P1 results in an estimated SINR of X decibels (dB), the transmit power level may be adjusted (Y-X) to (P1+ Y-X). In general, a higher set point and/or a lower estimated SINR may correspond to a higher transmit power, and vice versa. The transmit power may be given by a transmit Power Spectral Density (PSD), which may indicate the transmit power per unit frequency (e.g., per subcarrier). The estimated SINR may be obtained from one or more CQIs reported by the UE.

Different types of subframes may observe different levels of interference and, therefore, may be associated with different SINRs for a given amount of transmit power from the eNB. A single set point may be used for all subframes of different types and may be adjusted by the outer loop based on widely varying SINRs for different types of subframes. However, the outer loop may not converge due to large fluctuations in SINR, or may converge to a very conservative value, both of which are undesirable.

In another aspect, the eNB may maintain multiple set points for different types of subframes. In one design, an eNB may maintain a first setpoint for protected subframes (e.g., U and AU subframes) and a second setpoint for remaining subframes. In another design, the eNB may maintain a first setpoint for U and AU subframes, a second setpoint for N and AN subframes, and a third setpoint for AC subframes. In general, the eNB may maintain any number of setpoints for any number of subframe types. Different subframe types may be associated with different levels of interference, and thus different SINRs.

In one design, the eNB may maintain multiple set points for different subframe types for each UE of interest. In another design, the eNB may maintain multiple set points for different subframe types for a group of UEs or all UEs. In one design, the eNB may maintain multiple set points for different subframe types for each transmission type (e.g., for each physical channel). In another design, the eNB may maintain multiple set points for different subframe types for all transmission types (e.g., for all physical channels). In yet another design, the eNB may maintain multiple set points for different subframe types for each transmission type (e.g., for each physical channel) for each UE. The eNB may also maintain multiple set points for different subframe types in other manners.

The eNB may determine multiple setpoints for different subframe types in various ways. In one design, the eNB may set a set point for a subframe type based on a target performance level and a measured performance for the subframe type, as described above. For data transmission with HARQ, the eNB may use a lower set point for longer HARQ target termination and vice versa. In another design, the eNB may set a set point for a subframe type based on estimated interference in subframes of the subframe type. For example, the eNB may use a lower set point for a higher estimated interference and vice versa.

In one design, the eNB may determine the set point for each subframe type independently. In another design, the eNB may determine a first setpoint for a first subframe type and may determine a second setpoint for a second subframe type based on the first setpoint and an offset. The offset may be a fixed value or an adjustable value that may be changed based on the measured interference or the measured performance. The eNB may determine one or more additional setpoints for one or more other subframe types based on the one or more additional offsets.

The eNB may transmit control data and/or traffic data to a UE in a subframe based on a set point for the UE with respect to the subframe. The setpoint may be used to determine a transmit power level for transmitting data to the UE in the subframe.

The eNB may transmit a Physical Control Format Indicator Channel (PCFICH), a Physical HARQ Indicator Channel (PHICH), and a Physical Downlink Control Channel (PDCCH) in a control region of the subframe. The PCFICH may be transmitted in the first symbol period of the subframe and may communicate the size of the control region. The PHICH may carry ACK/NACK for data transmission with HARQ transmitted by the UE on the uplink. The PDCCH may carry control data/information regarding downlink grants, uplink grants, power control information, and the like. The PDCCH may be transmitted in 1, 2, 4, or 8 Control Channel Elements (CCEs), where each CCE includes 36 resource elements. The eNB may transmit the PDSCH in the data region of the subframe. The PDSCH may carry data for UEs scheduled for traffic data transmission on the downlink.

The eNB may send control data on the PDCCH to the UE in a subframe. In one design, for the PDCCH, the eNB may maintain multiple setpoints (or target PDCCHSINR) for different subframe types for the UE. The eNB may set a transmission power of the PDCCH based on a set point for a subframe in which the PDCCH is transmitted. For example, the eNB may use (i) a higher transmit power for the PDCCH for a higher setpoint or (ii) a lower transmit power for the PDCCH for a lower setpoint. The eNB may also set the transmit power of the PDCCH based on the CQI received from the UE for the subframe. For example, the eNB may use (i) a higher transmit power for the PDCCH for lower CQI values indicating poor channel quality, or (ii) a lower transmit power for the PDCCH for higher CQI values indicating better channel quality. The eNB may also set the transmit power of the PDCCH based on other factors. Alternatively, the eNB may use a fixed transmit power level for the PDCCH, but may change the number of CCEs used for control data transmission on the PDCCH. For example, the eNB may transmit the PDCCH (i) using more CCEs for higher set points and/or lower CQI values, or (ii) using fewer CCEs for lower set points and/or higher CQI values.

The eNB may send ACK/NACK on PHICH to the UE in a subframe. In one design, for PHICH, the eNB may maintain multiple setpoints (or targets PHICHSINR) for different subframe types for the UE. The eNB may set the transmit power of the PHICH based on the target PHICHSINR and the CQI received from the UE regarding the subframe in which the PHICH is sent.

The eNB may send traffic data on the PDSCH to the UE in a subframe. In one design, for PDSCH, the eNB may maintain multiple set points (or targets PDSCHSINR) for different subframe types for the UE. The eNB may set the transmit power of the PDSCH based on the target PDSCHSINR and the CQI received from the UE for the subframe in which the PDSCH is sent. The eNB may also set the transmit power of the PDSCH based on a target performance level for traffic data sent on the PDSCH. For example, the transmit power of the PDSCH may be set to meet a target Packet Error Rate (PER) of 1% (or some other value) based on a target number of packet transmissions. The eNB may also set the transmit power of the PDSCH based on the HARQ target termination. For example, the transmit power of the PDSCH may be set to meet the target PER based on the first transmission of the packet. In one design, progressively lower set points may be selected for progressively higher HARQ target terminations. Adjusting the transmit power of the PDSCH to obtain the desired HARQ target termination may be useful for certain traffic types such as, for example, voice over internet protocol (VoIP).

Using multiple set points for different subframe types may provide certain advantages. In wireless networks that use TDM resource partitioning for ICIC (e.g., as described above), interference on the downlink may vary significantly across subframes. The use of multiple set points may enable the eNB to apply appropriate transmit power levels in different subframes to achieve desired coverage within the cell under different interference scenarios.

Fig. 6 shows a design of a process 600 for determining a clean CQI. Process 600 may be performed by a UE (as described below) or by some other entity. The UE may receive signaling conveying resources allocated to the base station (block 612). The UE may determine at least one resource allocated to the base station with reduced or no interference from at least one interfering base station, e.g., based on the received signaling (block 614). The at least one resource may correspond to at least one subframe, or at least one sub-band, or at least one resource block, or some other type of resource allocated to the base station. The at least one resource may be semi-statically allocated to the base station via resource partitioning for the base station and the at least one interfering base station. The UE may determine a CQI based on the at least one resource (block 616). The UE may determine the CQI by excluding resources allocated to the at least one interfering base station. The UE may send the CQI to the base station (block 618). The UE may then receive a data (e.g., traffic data and/or control data) transmission sent by the base station based on the CQI (block 620).

Fig. 7 shows a design of a process 700 for receiving a clean CQI. Process 700 may be performed by a base station/eNB (as described below) or by some other entity. The base station may send signaling conveying resources allocated to the base station (block 712). The base station may receive a CQI determined by the UE based on at least one resource allocated to the base station with reduced or no interference from at least one interfering base station (block 714). The base station may send a data transmission to the UE based on the CQI (block 716).

Fig. 8 shows a design of a process 800 for determining multiple CQIs for different resources. Process 800 may be performed by a UE (as described below) or by some other entity. The UE may receive resource partitioning information from a base station (block 812). The resource partitioning information may convey subframes (e.g., U subframes) semi-statically allocated to the base station and subframes (e.g., N subframes) semi-statically allocated to at least one interfering base station. The UE may determine at least one first subframe allocated to the base station and at least one second subframe allocated to the at least one interfering base station based on the resource partitioning information (block 814).

The UE may determine a first CQI based on the at least one first subframe allocated to the base station with reduced or no interference from the at least one interfering base station (block 816). The UE may determine a second CQI based on the at least one second subframe allocated to the at least one interfering base station (block 818). The UE may send a first CQI and a second CQI to the base station (block 820). The UE may then receive a data transmission sent by the base station based on the first CQI and/or the second CQI (block 822).

The UE may determine the second CQI in various ways. In a first design, the UE may determine the second CQI based only on the at least one second subframe (e.g., N subframes only) allocated to the at least one interfering base station and not based on any subframes semi-statically allocated to the base station. In a second design, the UE may determine the second CQI by averaging over a set of subframes including the at least one second subframe. In one design, the set of subframes may not include subframes (e.g., U subframes) semi-statically allocated to the base station. In another design, the set of subframes may not include subframes semi-statically allocated to the base station (e.g., U subframes) and subframes semi-statically allocated to the at least one interfering base station (e.g., N subframes). The number of subframes in the set of subframes may be a fixed value, or configured by the base station and signaled to the UE, or determined based on resource partitioning for the base station and the at least one interfering base station, or otherwise ascertained.

In a third design, the UE may determine the second CQI based on total interference in the at least one first subframe and the at least one second subframe. The UE may estimate interference in the at least one first subframe (e.g., U subframe) allocated to the base station. The UE may also estimate interference in the at least one second subframe (e.g., N subframes) allocated to the at least one interfering base station. The UE may estimate the total interference based on the estimated interference in the at least one first subframe and the estimated interference in the at least one second subframe. The UE may then determine a second CQI based on the estimated total interference.

In a fourth design, the UE may determine the at least one second subframe based on an offset with respect to a subframe in which the second CQI is reported (or a subframe used to determine the first CQI). In one design, the UE may receive signaling from the base station conveying the offset. In another design, the UE may determine the offset by cycling through a set of offsets and selecting different subframes in different periods to determine the second CQI. The UE may receive signaling from the base station conveying the set of offsets and/or the number of offsets.

The UE may also determine a second CQI based on the at least one subframe determined in other manners. The UE may also determine at least one additional CQI based on the at least one additional subframe.

The UE may report the first and second CQIs in various manners. In one design, the UE may report the first and second CQIs with the same periodicity (e.g., in the same subframe or different subframes). In another design, the UE may report the first CQI at a first periodicity and may report the second CQI at a second periodicity different from the first periodicity (e.g., a second periodicity less frequent than the first periodicity). In one design, the UE may report a first CQI based on a first CQI configuration and may report a second CQI based on a second CQI configuration different from the first CQI configuration. Each CQI configuration may be associated with various parameters for reporting CQI, such as periodicity for reporting CQI, which subframes are used for transmitting CQI, etc.

Fig. 9 shows a design of a process 900 for receiving multiple CQIs for different resources. Process 900 may be performed by a base station/eNB (as described below) or by some other entity. The base station may transmit (e.g., broadcast) resource partitioning information conveying subframes allocated to the base station and subframes allocated to at least one interfering base station (block 912). The base station may receive a first CQI and a second CQI from the UE (block 914). The first CQI may be determined based on at least one first subframe allocated to the base station with reduced or no interference from the at least one interfering base station. The second CQI may be determined based on at least one second subframe allocated to the at least one interfering base station. The second CQI may be determined by the UE in various ways, e.g., as described above. The base station may send a data transmission to the UE based on the first CQI and/or the second CQI (block 916).

FIG. 10 shows a design of a process 1000 for transmitting data. Process 1000 may be performed by a base station/eNB (as described below) or by some other entity. The base station may maintain multiple set points for multiple subframe types associated with different interference levels (block 1012). The base station may select a setpoint from the plurality of setpoints based on a subframe in which data is transmitted to the UE (block 1014). The base station may receive CQI from the UE applicable for the subframe (block 1016). The base station may transmit data to the UE in the subframe based on the selected set point and possibly also based on the CQI (block 1018). The base station may transmit data on PDCCH, PHICH, PDSCH, or some other physical channel.

In one design of block 1012, the base station may determine the set point for each subframe type based on one or more metrics, such as estimated interference for subframes of the subframe type, a target performance level, a target error rate, a HARQ target termination, some other metric, or a combination thereof.

In one design, a base station may maintain multiple set points for multiple subframe types for a UE. The base station may maintain multiple set of setpoints for multiple UEs, one set of setpoints for each UE. In another design, the base station may maintain multiple set points for multiple subframe types for a particular physical channel. The base station may maintain multiple set of setpoints for multiple physical channels, one set of setpoints for each physical channel. In yet another design, the base station may maintain multiple set points for multiple subframe types for a particular physical channel with respect to the UE. The base station may also maintain multiple set points for multiple subframe types in other manners.

In one design, the base station may determine the transmit power level based on a selected set point and the CQI. The base station may transmit data to the UE based on the determined transmit power level. In another design, the base station may determine an amount of resources (e.g., a number of CCEs or resource blocks) to transmit data to the UE based on the selected set point and the CQI. The base station may transmit data to the UE based on the determined amount of resources. The base station may also determine other parameters for data transmission based on the set point and the CQI.

FIG. 11 shows a block diagram of a design of base station/eNB 110x and UE120x, which may be one of the base stations/eNBs and one of the UEs in FIG. 1. Within UE120x, a receiver 1110 may receive and process downlink signals from base station 110x and other base stations. Module 1112 may process (e.g., demodulate and decode) the received data transmission. Module 1114 may estimate interference in different types of subframes. Module 1116 may determine a clean CQI and an unclean CQI based on the estimated interference for different types of subframes, as described above. Module 1118 may generate and send a CQI report as configured for UE120 x. Module 1122 can receive signaling (e.g., SRPI) indicating subframes allocated to base station 110x and can determine different types of subframes. Various modules within UE120x may operate as described above. A controller/processor 1124 may direct the operation of various modules within UE120 x. Memory 1126 may store data and program codes for UE120 x.

Within base station 110x, module 1152 may generate data transmissions to UE120x and/or other UEs. Module 1154 may determine the transmit power level for each data transmission based on a set point applicable for that data transmission. A transmitter 1154 may generate a downlink signal including the data transmission and may transmit the downlink signal to UE120x and other UEs. Receiver 1156 may receive and process uplink signals transmitted by UE120x and other UEs. Module 1158 may process the received signal to recover the CQI report sent by UE120 x. Module 1160 may obtain clean CQI and unclean CQI from CQI reports sent by UE120x and may select a modulation and coding scheme for each data transmission to UE120x based on applicable CQI and/or other information. Module 1162 may determine subframes allocated to base station 110x and may generate resource partitioning information (e.g., SRPI) indicating different types of subframes for base station 110 x. Various modules within base station 110x may operate as described above. A controller/processor 1164 may direct the operation of various modules within base station 110 x. A memory 1166 may store data and program codes for base station 110 x. A scheduler 1168 may schedule UEs for data transmission.

The modules in fig. 11 may comprise processors, electronics devices, hardware devices, electronics components, logic circuits, memories, software codes, firmware codes, etc., or any combination thereof.

FIG. 12 shows a block diagram of a design of base station/eNB 110y and UE120y, which may be one of the base stations/eNBs and one of the UEs in FIG. 1. Base station 110y may be equipped with T antennas 1234a through 1234T and UE120y may be equipped with R antennas 1252a through 1252R, where T ≧ 1 and R ≧ 1 in general.

At base station 110y, a transmit processor 1220 may receive traffic data from a data source 1212 for one or more UEs, select one or more Modulation and Coding Schemes (MCSs) for each UE based on the CQI received from the UE, process (e.g., encode and modulate) the traffic data for the UE based on the MCS selected for the UE, and provide data symbols to all UEs. Transmit processor 1220 may also process system information (e.g., SRPI, etc.) and control data/information (e.g., regarding offsets, grants, upper layer signaling, etc.), and provide overhead symbols and control symbols. Processor 1220 may also generate reference symbols for reference signals (e.g., CRS) and synchronization signals (e.g., PSS and SSS). A Transmit (TX) multiple-input multiple-output (MIMO) processor 1230 may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, the overhead symbols, and/or the reference symbols, if applicable, and may provide T output symbol streams to T Modulators (MODs) 1232a through 1232T. Each modulator 1232 may process a respective output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator 1232 may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. T downlink signals from modulators 1232a through 1232T may be transmitted via T antennas 1234a through 1234T, respectively.

At UE120y, antennas 1252a through 1252r may receive the downlink signals from base station 110y and/or other base stations and may provide received signals to demodulators (DEMODs) 1254a through 1254r, respectively. Each demodulator 1254 may condition (e.g., filter, amplify, downconvert, and digitize) its received signal to obtain input samples. Each demodulator 1254 may further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. A MIMO detector 1256 may obtain received symbols from all R demodulators 1254a through 1254R, perform MIMO detection on the received symbols as applicable, and provide detected symbols. A receive processor 1258 may process (e.g., demodulate and decode) the detected symbols, provide decoded traffic data for UE120y to a data sink 1260, and provide decoded control data and system information to a controller/processor 1280. A channel processor 1284 may estimate interference in different types of subframes and determine clean and unclean CQIs based on the estimated interference, as described above.

On the uplink, at UE120y, a transmit processor 1264 may receive and process traffic data from a data source 1262 and control data (e.g., for CQI reports) from a controller/processor 1280. Processor 1264 may also generate reference symbols for one or more reference signals. The symbols from transmit processor 1264 may be precoded by a TXMIMO processor 1266 if applicable, further processed by modulators 1254a through 1254r (e.g., for SC-FDM, OFDM, etc.), and transmitted to base station 110 y. At base station 110y, the uplink signals from UE120y, as well as other UEs, may be received by antennas 1234, processed by demodulators 1232, detected by a MIMO detector 1236 if applicable, and further processed by a receive processor 1238 to obtain the decoded traffic data and control data sent by UE120 y. Processor 1238 may provide decoded traffic data to a data sink 1239 and decoded control data to controller/processor 1240.

Controllers/processors 1240 and 1280 may direct the operation at base station 110y and UE120y, respectively. Processor 1280 and/or other processors and modules at UE120y may perform or direct process 600 in fig. 6, process 800 in fig. 8, and/or other processes for the techniques described herein. Processor 1240 and/or other processors and modules at base station 110y may perform or direct process 700 in fig. 7, process 900 in fig. 9, process 1000 in fig. 10, and/or other processes for the techniques described herein. Memories 1242 and 1282 may store data and program codes for base station 110y and UE120y, respectively. A scheduler 1244 may schedule UEs for data transmission on the downlink and/or uplink.

Those of skill in the art would understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

Those of skill would further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the disclosure herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure.

The various illustrative logical blocks, modules, and circuits described in connection with the disclosure herein may be implemented or performed with a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

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

In one or more exemplary designs, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code means in the form of instructions or data structures and which can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a web site, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk (disk) and disc (disc), as used herein, includes Compact Disc (CD), laser disc, optical disc, Digital Versatile Disc (DVD), floppy disk and blu-ray disc where disks (disks) usually reproduce data magnetically, while discs (discs) reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. A method for wireless communication, comprising:

receiving signaling from a base station conveying resources allocated to the base station;

determining, based on the received signaling, at least one resource allocated to the base station with reduced or no interference from at least one interfering base station, the at least one resource being semi-statically allocated to the base station via resource partitioning for the base station and the at least one interfering base station; and

determining a Channel Quality Indicator (CQI) based on the at least one resource.

2. The method of claim 1, further comprising:

transmitting the CQI to the base station; and

receiving a data transmission sent by the base station based on the CQI.

3. The method of claim 1, wherein the CQI is determined by excluding resources allocated to the at least one interfering base station.

4. The method of claim 1, wherein the at least one resource corresponds to at least one subframe allocated to the base station.

5. An apparatus for wireless communication, comprising:

means for receiving signaling from a base station conveying resources allocated to the base station;

means for determining, based on the received signaling, at least one resource allocated to the base station and having reduced or no interference from at least one interfering base station, the at least one resource semi-statically allocated to the base station via resource partitioning for the base station and the at least one interfering base station; and

means for determining a Channel Quality Indicator (CQI) based on the at least one resource.

6. An apparatus for wireless communication, comprising:

at least one processor configured to receive signaling from a base station conveying resources allocated to the base station, determine at least one resource allocated to the base station with reduced or no interference from at least one interfering base station based on the received signaling, the at least one resource semi-statically allocated to the base station via resource partitioning for the base station and the at least one interfering base station, and determine a Channel Quality Indicator (CQI) based on the at least one resource.

7. A method for wireless communication, comprising:

sending signaling to a User Equipment (UE) conveying resources allocated to a base station;

receiving a Channel Quality Indicator (CQI) determined by the UE based on at least one communicated resource allocated to the base station and having reduced or no interference from at least one interfering base station, the at least one resource semi-statically allocated to the base station via resource partitioning for the base station and the at least one interfering base station; and

sending a data transmission to the UE based on the CQI.

8. The method of claim 7, wherein the at least one resource corresponds to at least one subframe.

9. An apparatus for wireless communication, comprising:

means for transmitting signaling conveying resources allocated to a base station to a User Equipment (UE);

means for receiving a Channel Quality Indicator (CQI) determined by the UE based on at least one communicated resource allocated to the base station and having reduced or no interference from at least one interfering base station, the at least one resource semi-statically allocated to the base station via resource partitioning for the base station and the at least one interfering base station; and

means for sending a data transmission to the UE based on the CQI.

10. An apparatus for wireless communication, comprising:

at least one processor configured to send signaling conveying resources allocated to a base station to a User Equipment (UE), receive a Channel Quality Indicator (CQI) determined by the UE based on at least one conveyed resource allocated to the base station and having reduced or no interference from at least one interfering base station, the at least one resource semi-statically allocated to the base station via resource partitioning for the base station and the at least one interfering base station, and send a data transmission to the UE based on the CQI.