HK1228116A1 - Apparatus of user equipment, apparatus of an enhanced node b and storage medium - Google Patents

Abstract

The invention relates to enhanced node B and methods for network assisted interference cancellation with reduced signaling. Embodiments of an enhanced node B (eNB) and methods for network-assisted interference cancellation with reduced signaling in a 3GPP LTE network are generally described herein. In some embodiments, the number of transmission options is reduced by introducing a smaller signaling codebook. In some embodiments, higher-layer feedback from the UE to the eNodeB is established to inform the eNB about certain NA-ICS capabilities of the UE. In some embodiments, the number of signaling options is reduced by providing only certain a priori information. In some embodiments, correlations in the time and/or frequency domain are exploited for reducing the signaling message. In some embodiments, differential information is signaled in the time and/or frequency domain for reducing the signaling message.

Description

Enhanced node B and method for network assisted interference cancellation with reduced signaling

Description of divisional applications

The present application is a divisional application of chinese patent application No.201480031508.6 entitled "enhanced node B and method for network assisted interference cancellation with reduced signaling" filed as 2014, month 07, 08.

RELATED APPLICATIONS

This application claims priority to U.S. patent application serial No. 14/134,461 filed on 19.12.2013 and U.S. provisional patent application serial No. 61/843,826 filed on 8.7.2013, each of which is incorporated herein by reference in its entirety.

Technical Field

Embodiments relate to wireless communications. Some embodiments relate to interference cancellation, including network assisted interference cancellation in 3GPP-LTE networks.

Background

Inter-cell, as well as intra-cell, co-channel interference mitigation is one of the most critical tasks in Long Term Evolution (LTE) User Equipment (UE) receivers in order to optimize Downlink (DL) throughput and minimize radio link failure. The type of interference experienced by the UE may vary with Physical Resource Blocks (PRBs) and with Transmission Time Intervals (TTIs). Furthermore, the type of interference experienced by the UE depends on the type of allocation received by the UEs in the neighboring cells from their serving enhanced node b (enb). Conventional interference mitigation techniques do not effectively address these types of interference.

Accordingly, there is a general need for improved interference mitigation techniques in LTE networks. There is a general need for more efficient interference mitigation techniques in LTE networks.

Drawings

Fig. 1 illustrates a portion of an end-to-end network architecture of an LTE (long term evolution) network having various components of the network, according to an embodiment;

fig. 2 illustrates interference variation with PRBs and with TTIs, according to some embodiments.

Fig. 3 illustrates a structure of a downlink resource grid for downlink transmission from an eNB to a UE, in accordance with some embodiments.

Fig. 4 illustrates a functional block diagram of a UE in accordance with some embodiments.

Detailed Description

The following description and the drawings sufficiently illustrate specific embodiments to enable those skilled in the art to practice them. Other embodiments may incorporate structural, logical, electrical, process, and other changes. Portions and features of some embodiments may be included in or substituted for those of others. Embodiments set forth in the claims encompass all available equivalents of those claims.

Fig. 1 illustrates a portion of an end-to-end network architecture of an LTE network having various components of the network, in accordance with some embodiments. The network includes a radio access network (e.g., the depicted E-UTRAN or evolved universal terrestrial radio access network) 102 and a core network (EPC)120, the radio access network 102 and EPC 120 being coupled together by an S1 interface 115. Note that for convenience and brevity, only a portion of the core network and RAN are shown.

The core network (EPC)120 includes a Mobility Management Entity (MME)122, a serving gateway (serving GW)124, and a packet data network gateway (PDN GW) 126. The RAN 102 includes a macro base station (also referred to as macro eNodeB or eNB)105, Low Power (LP) base stations (or LP enbs) 106, 107, and UEs (user equipment or mobile terminals) 110.

The MME is functionally similar to the control plane of a conventional Serving GPRS Support Node (SGSN). The MME manages mobility aspects in access such as gateway selection and tracking area list management. The serving GW 124 terminates the interface towards the RAN and routes data packets between the RAN and the core network. Further, it may be a local mobility anchor (anchor point) for inter eNode-B handover, and may also provide an anchor for inter 3GPP mobility. Other responsibilities may include lawful interception, billing, and some policy enforcement. The serving GW and MME may be implemented in one physical node or in separate physical nodes. The PDNGW terminates the SGi interface towards the Packet Data Network (PDN). It routes data packets between the EPC and the external PDN, and may be a key node for policy enforcement and charging data collection. It may also provide an anchor point for mobility with non-LTE access. The external PDN may be any kind of IP network, as well as an IP Multimedia Subsystem (IMS) domain. The PDN GW and the serving GW may be implemented in one physical node or in separate physical nodes.

The eNode-bs (macro eNode-B and micro eNode-B) terminate the air interface protocol and are typically (although not necessarily) the first contact point for the UE 110. In some embodiments, the eNode-B may implement various logical functions of the RAN including, but not limited to, RNC (radio network controller functions) such as radio bearer management, uplink and downlink dynamic radio resource management and data packet scheduling, and mobility management.

The S1 interface is an interface that separates the RAN and the EPC. The S1 interface is divided into two parts: S1-U and S1-MME, wherein S1-U carries traffic data between eNode-B and serving GW, and S1-MME is the signaling interface between eNode-B and MME. The X2 interface is an interface between eNode-bs (at least between most eNode-bs, as will be discussed below with respect to micro enbs). The X2 interface includes two parts: X2-C and X2-U. X2-C is a control plane interface between eNode-Bs, while X2-U is a user plane interface between eNode-Bs.

For cellular networks, LP cells are typically used to extend coverage to indoor areas where outdoor signals do not reach well, or to increase network capacity in areas where telephone usage is very dense (e.g., train stations). As used herein, the term Low Power (LP) eNB refers to any suitable relatively low power eNode-B used to implement a narrower cell (narrower than a macro cell), such as a femto cell, pico cell, or micro cell. A femtocell eNB is typically provided to its residential or enterprise users by a mobile network operator. A femto cell is typically the size of a residential gateway or smaller and is typically connected to a subscriber's broadband line. Once plugged in, the femto cell connects to the mobile operator's mobile network and provides additional coverage for the residential femto cell, typically in the range of 30 to 50 meters. Thus, LPeNB 107 may be a femto cell eNB because it is coupled through PDN GW 126. Similarly, a pico cell is a wireless communication system that generally covers a small area, such as inside a building (office, shopping center, train station, etc.), or recently on an airplane. A picocell eNB may typically connect to another eNB (e.g., a macro eNB) through an X2 link through its Base Station Controller (BSC) functionality. Thus, LP eNB 106 may be implemented with a picocell eNB since it is coupled to a macro eNB via an X2 interface. Thus, a pico cell eNB or other LP eNB may contain some or all of the functionality of a macro eNB. In some cases, it may be referred to as an access point base station, or an enterprise femtocell.

According to embodiments, the eNB may be arranged to provide Network Assisted (NA) interference cancellation signaling (NA-ICS) to the UE 110 for coordinating interference mitigation, Interference Cancellation (IC) or for performing Interference Suppression (IS). In some embodiments, the number of transmission options is reduced by introducing a smaller signaling codebook. In some embodiments, higher layer feedback from the UE to the eNodeB is established to inform the eNB about certain NA-ICS capabilities of the UE. In some embodiments, the number of signaling options is reduced by providing only certain a priori information. In some embodiments, correlation in the time and/or frequency domain is used to reduce signaling messages. In some embodiments, the difference information is signaled in the time and/or frequency domain for reducing the NA-ICS message. These embodiments are discussed in more detail below. In some embodiments, the eNB may include physical layer circuitry and processing circuitry to provide network assistance to the UE 110 for coordinated interference mitigation as discussed herein.

Fig. 2 illustrates how the type of interference varies from PRB to PRB and from TTI to TTI, according to some embodiments. As mentioned above, inter-cell, as well as intra-cell, co-channel interference mitigation is one of the more and more critical tasks in UE receivers in order to optimize Downlink (DL) throughput and minimize radio link failure. Mitigation of co-channel interference would benefit from network assistance when optimizing UE receiver performance or when balancing performance with UE receiver power consumption and/or UE cost. In these embodiments, the LTE network may provide side information (side information) or coordination or a combination of both in order to simplify, enable, or optimize Interference Cancellation (IC) or Interference Suppression (IS) in the UE receiver. The network assistance information may be referred to as "IC/IS side information", and (1) a modulation order and (2) precoder information (e.g., codebook, # TX, # layer, PMI) of the interfering signal may be part of the IC/IS side information provided to the UE. For example: with such IC/IS side information, a (approximate) maximum likelihood detector in the UE detecting resource blocks 202 (fig. 2) would (ideally) also be able to demodulate interfering (UE allocated RBs 204) signals falling into the allocated resource blocks of the desired UE, so that the cancellation of the UE allocated signals (RBs 204) can be done ideally, improving the DL throughput of the UE in the serving cell 201. For inter-cell co-channel interference scenarios in all deployment scenarios (especially in homogeneous macro networks), the appropriate/efficient method(s) for signaling IC/IS side information to LTE UEs for general inter-cell co-channel interference scenarios may need to be addressed: particularly methods that meet signaling requirements, minimize changes to LTE standards and/or UE receiver implementations, and optimize network assistance.

Some embodiments disclosed herein address minimizing the amount of IC/IS side information, and in some embodiments, minimizing the amount of resources needed to provide network assistance information. Embodiments disclosed herein provide several methods for reducing network assisted interference cancellation and/or suppressing the amount of side information that a receiver has to transmit. Minimization of signaling is not only an optimization of the possible NA-ICS scheme, but also may be seen as a requirement in case of very limited available signaling bandwidth and a large number of interfering transmission schemes that can be used and need to be signalled. In a simple implementation, all information sent via the PDCCH will need to be available to the interfering UE as well.

According to an embodiment, a signaling method for minimizing NA-ICS side information is provided. Depending on the kind of signaling method used, the serving eNB or each interfering eNB may signal NA-ICS side information to the UE.

In the first part of this section, possible transmission options in LTE are outlined and the reason why signaling overhead should be minimized is explained. The second section discloses several embodiments that can achieve significant signaling reduction.

Possible transmission configurations for each interfering signal:

depending on the transmission mode of the interfering cell and its configuration, the effective channel can be estimated directly from the precoded demodulated reference symbols or has to be calculated from the estimates of the interfering channel (derived from the cell-specific reference symbols) and the precoding (has to be explicitly signaled). In any case, a set of modulation symbols for a single transport block (i.e., QPSK, 16QAM, or 64QAM) or a pair of modulation schemes for two transport blocks must be explicitly signaled. The number of transmit antenna ports (applicable to transmission modes 1-6) used by the interferer, as well as the cell-id, may be derived by the UE or signaled (semi-) statically.

The following table (table 1) provides an overview of each transmission mode used by the interfering cells. In the last column of the table, the number of possible configuration options is listed. These numbers are primarily intended to show the range of possible configuration options rather than the exact number, as this depends on further assumptions for some transmission modes.

Table 1: overview of Transmission mode and IC/IS Signaling requirements

SFBC transmissions may be used as fallback (fallback) in almost all other transmission modes. Embodiments disclosed herein do not need to distinguish between fallback/non-fallback operation in other transmission modes, as SFBC/TM2 may be signaled to indicate fallback operation.

From the above summary, for the LTE Rel-11 system, approximately 800 different transmission options would need to be distinguished for signaling NA-ICS side information to the UE. An appropriate message would therefore require 10 bits and would only be valid for transmissions from one eNodeB on one PRB and TTI. A single eNodeB would therefore have to provide up to 100 x 10 ═ 10 kilobits of signaling information for transmission on 100 PRBs (20MHz system bandwidth) per 1ms TTI, yielding a signaling data rate of 10 megabits per second (10 Mbit/s). A NA-ICS capable UE may want to suppress multiple interfering enodebs so that the required signaling rate will scale further. Clearly, such high signaling rates would be prohibitive or at least severely limit the possible performance gains.

Method for minimizing the required signaling information:

the basis for the following method is the presence of a master codebook that includes all possible interfering transmission configurations (and possibly more) as exemplified in the table above.

The method A comprises the following steps: the number of transmission options is reduced by introducing smaller signaling codebooks:

although there are a large number of different transmission possibilities in LTE, only a subset of them will be used in practical systems. This forces limiting the amount of information exchanged per TTI to a subset of the most relevant possibilities for longer periods of time, e.g., seconds (thousands of TTIs) or even longer. A master codebook may be provided, the master codebook containing all of the more than 800 transmission options shown in the table above, for example. The entries in such a codebook may be encoded with 10 bits or even more. A smaller signaling codebook may be provided that allows the most relevant interfering transmission options to be distinguished from those available from a larger main codebook. Such a codebook may have a small size, e.g. 8 entries (3 bits) or 16 entries (4 bits), and will therefore significantly limit the amount of information that has to be signaled TTI by TTI. The signaling codebook may be established semi-statically based on higher layer signaling between the eNodeB and the UE, e.g. when it registers in the system or initiates high data rate transmission (NA-ICS support would be beneficial for high data rate transmission). Higher layer signaling would require the eNodeB to communicate which entries in the smaller signaling codebook are to be populated with (i.e., associated with) which entries from the main codebook. For example, in the case of a 16 entry signaling codebook, 160(16 x 10 ═ 160) bits would be required to signal the full codebook or 14(4+10 ═ 14) bits would be sufficient to update a single entry in the signaling codebook.

Since only a few bits are needed to update the entries of the signaling codebook, the eNB may also adapt to signaling codebooks within shorter time frames (e.g., on the order of 50 to 1000 TTIs) to reflect the current scheduling situation. For example, based on the downlink traffic situation, the eNB serving a user in the interfering cell may predict that the user will be scheduled in the recent future and that it is likely that only a single or at least only a very limited number of transmission configurations will be used (e.g., only a single transmission mode, the same number of layers, the same modulation scheme, etc.). In this case, the transmission configuration may be dynamically added to the signaling codebook.

The signaling codebook may also contain default entries (e.g., 0) that only indicate that none of the previously exchanged options are applicable, such that the UE must operate without NA-ICS support.

As mentioned above, embodiments disclosed herein are directed to reducing NA-ICS signaling messages. The expected signaling codebook may be established using (higher layer) RRC signaling between the UE and its serving eNB. Short-term per-TTI signaling using the reduced codebook may then be implemented with DCI indications from the serving eNB to the interfered UE. However, especially for short-term signaling, different signaling mechanisms that do not rely on extended DCI signaling are feasible. For example, the short-term signaling may be provided by the serving eNB using a non-DCI message, or it may come directly from the interfering eNB.

There are many reasons why a smaller signaling codebook may be sufficient to capture the most important transmission options from the many transmission options shown in the table:

the interfering eNodeB may have hardware limitations (e.g. only 2 Tx antennas) that permanently exclude a large number of options. For example, it would not be possible to have all options with a rank greater than 2.

The interfering enodebs are configured to operate only with specific transmission schemes or even not support these specific transmission schemes based on their hardware or firmware implementations.

In the case of high-proportion line-of-sight transmissions, typical propagation conditions in interfering cells can, for example, make very rare use of, for example, more than 2 transmission layers.

Some interfering transmission options may be inappropriate candidates for NA-ICS operation, e.g. (assuming) that the UE may not benefit from the knowledge that the interferer has a 4-layer transmission with 64QAM, since such transmission is already very similar to AWGN (AWGN corresponds to an infinite number of layers or other kind of transmission, higher order modulation is also close to AWGN).

With codebook based precoding (in TM 4), the eNodeB may apply codebook subset restriction such that some PMIs will never be used in the cell.

Some theoretically feasible transmission options in LTE may be very rare, such as operation with CDD open loop MIMO in TM3, where the modulation on the two transport blocks is (very) different.

Some LTE transmission modes may never be used in practice, as they are optional (e.g. TM5) or will only be used in faulty systems (e.g. TM1 with an eNB equipped with two antennas).

The method B comprises the following steps: establishing higher layer feedback from UE to eNodeB to inform of specific NA-ICS capabilities

The signaling codebook approach mentioned in approach a may be extended by including feedback from the UE, i.e. by introducing a handshake (handshake), where the UE indicates that NA-ICS would be a very advantageous or completely disadvantageous use case based on a NA-ICS receiver implemented in the UE. In this way, the eNodeB may limit signaling to only those use cases that are most promising to assist the UE receiver. For example (assuming), a particular UE receiver implementation may not benefit from knowledge that the interference is modulated with 64QAM or that it is using DM-RS based transmission, or that it cannot cancel more than the maximum number of layers.

The method C comprises the following steps: reducing the number of signaling options by providing only certain a priori information

The UE receiver may be able to blindly detect the presence and structure of a particular interfering transmission. For example, for intra-cell or inter-cell DM-RS based interference, the UE may be able to autonomously detect the presence of an interfering layer and thus may only be interested in information about the modulation scheme. Or as another example, the UE receiver may be a large part of a structure that is very powerful and capable of autonomously detecting interfering transmissions, but would require prohibitive amounts of time or computational resources and power to do so. To accommodate such a situation, some embodiments may increase the master codebook of all possible transmission options to additionally include the categories of transmission options (by signaling these categories of transmission options via the signaling codebook), providing the UE with the most helpful a priori side information. As an example, the master codebook would then contain entries for transmission schemes such as:

o SFBC

codebook based precoding

o CDD open loop precoding

Omicron DM-RS based transmission

Omicron DM-RS based multi-user

DM-RS based CoMP

o modulation of only one transport block

Modulation combination of o two transport blocks

Additionally or separately, the provision of side information may also be done by providing the UE with transmission statistics. For example, if the eNodeB semi-statically provides a histogram of the frequencies used in the cell for different transmission modes, the UE can align its blind decoding strategy by testing the transmission hypotheses for the likelihood of transmission. The histogram information may be provided with more or less quantized details (e.g., low to single digit percentage or coarse binary, such as "top 5%", "top 10%", "top 35%", "remaining"). Such statistical side information may be provided instead of (and thus completely save) short-term signaling or as backup information for assisting the UE in blind decoding, if the particular transmission option is not included in the current signaling codebook.

The method D comprises the following steps: the correlation in time and frequency domain is used to reduce signaling messages:

the allocation of interfering transmissions may change per PRB and per TTI because the schedulers in the interfering cells are free to schedule their users in the way they want. However, there is often a dependency in the time and frequency domain, since interfering users are typically allocated more than 1 PRB, e.g. because PRBs have to be allocated per resource block group, depending on the type of resource allocation used. The LTE standard requires that all PRBs belonging to one user in the considered TTI show the same number of layers and that each layer shows the same modulation scheme. Furthermore, precoding may be different between different PRBs, but since the CSI (PMI) feedback, from which the eNodeB selects the downlink precoder (in FDD systems), is only subband specific and therefore identical for multiple adjacent PRBs, the precoders for adjacent PRBs will typically be the same (in fact, for TM9 and TM10 which rely on frequency domain PMI/RI reporting, the precoding for adjacent PRB groups must be the same, see 7.1.6.5 "PRB bundling" in 36.213). Furthermore, the PRBs used for transmission to one user cannot be distributed in an arbitrary manner over the frequency range. On the one hand, the downlink control information only allows for signaling of a specific allocation type (e.g. resource block group) and on the other hand, the CQI feedback may also be subband specific only, so that the scheduler will typically allocate contiguous PRBs (contiguous PRB group).

Therefore, the NA-ICS feedback message may be designed to differentially encode only the status of the neighbor PRBs. One example implementation of this signaling would signal one entry of a signaling codebook (e.g., 4 bits) for a set of 4 PRBs and provide a bitmap to which of the 4 PRBs (4 bits) the message is valid. Instead of 4 bits, it may be sufficient to signal only 3 bits, because there is less motivation to indicate a configuration that is not related to any PRB (one case), or only to a single PRB (4 cases), and it is not possible to apply it to two non-adjacent PRBs (3 cases: XooX, XoXo, oXoX), leaving the remaining 8(16-1-4-3 ═ 8) cases to be transmitted with 3 bits. That way, the NA-ICS side information may be provided with 7 bits (or 8 bits) instead of 16 bits for up to 4 PRBs in this example. To enable a larger PRB group (where one NA-ICS signaling information is valid for as many PRBs as possible), the eNodeB scheduler may be caused to schedule the compatible PRB group accordingly. However, such scheduling restrictions may result in system performance penalties.

Another way to reduce the signaling would be to exploit the correlation in the time domain between TTIs. This may be done in a similar manner as before, and may for example additionally consider a semi-persistent scheduling (SPS) configuration. Finally, scheduling in neighboring cells may be made more predictable by the interfered UE so that it will already know the NA-ICS information in advance. Furthermore, however, such restrictions on scheduling in the system are likely to cause large performance degradation.

The method E comprises the following steps: signaling difference information in the time and/or frequency domain to reduce signaling messages:

this method is similar to the previous method, but it does not rely on the same configuration in adjacent PRBs, but rather signals the differences. The method is advantageous in the following cases: the configuration for the two UEs is similar, which is likely the case, since the UEs are located in the same cell and may therefore experience similar channels (at least when located in similar regions of the cell), e.g. experience similar ranks of channels and thus similar numbers of layers. The configuration of the first UE will be signaled as usual, but only the difference is signaled for the second UE. In the simplest case (and the most common case), two configurations of two UEs are signaled, and it is divided which PRBs are used for one configuration and which are used for the other configuration. The latter information may be signaled using bitmap type signaling as mentioned above, but it is likely to be sufficient to give one range (or pair of ranges) to which each UE is scheduled.

Fig. 3 illustrates a structure of a downlink resource grid for downlink transmission from an eNB to a UE, in accordance with some embodiments. The depicted grid shows a time-frequency grid (referred to as a resource grid), which is the physical resource in the downlink in each slot. Such a time-frequency plane representation is a common practice for OFDM systems, which makes it intuitive for radio resource allocation. Each column and each row of the resource grid corresponds to one OFDM symbol and one OFDM subcarrier, respectively. The duration of the resource grid in the time domain corresponds to one time slot in a radio frame. The smallest time-frequency unit in the resource grid is represented as a resource element. Each resource grid comprises a number of resource blocks, which describe the mapping of a particular physical channel to resource elements. Each resource block includes many resource elements, and in the frequency domain this represents the minimum amount of resources that can currently be allocated. There are several different physical downlink channels that are transmitted using such resource blocks. Particularly relevant to the present disclosure, two of these physical downlink channels are a physical downlink shared channel and a physical downlink control channel.

The Physical Downlink Shared Channel (PDSCH) conveys user data and higher layer signaling to UE 110 (fig. 1). A Physical Downlink Control Channel (PDCCH) transmits information on a transport format and resource allocation related to a PDSCH channel, and the like. The PDCCH also informs the UE about transport format, resource allocation, and H-RAQ information related to the uplink shared channel. In general, downlink scheduling (assigning control and shared channel resource blocks to UEs within a cell) is performed at the eNB based on channel quality information fed back from the UE to the eNB, and then downlink resource allocation information is transmitted to the UE on a control channel (PDCCH) for (assigned to) the UE.

The PDCCH transmits control information using CCEs (control channel elements). The PDCCH complex-valued symbols are first organized into quads (quadruplets) before being mapped to resource elements, which are then aligned for rate matching using a sub-block interleaver. Each PDCCH is transmitted using one or more of these Control Channel Elements (CCEs), where each CCE corresponds to nine sets of four physical resource elements, referred to as Resource Element Groups (REGs). Four QPSK symbols are mapped to each REG. The PDCCH may be transmitted using one or more CCEs (depending on the DCI size and channel conditions). There may be four or more different PDCCH formats defined in LTE with different numbers of CCEs (e.g., aggregation level, L ═ 1, 2, 4, or 8).

Fig. 4 illustrates a functional block diagram of a UE in accordance with some embodiments. UE 400 may be adapted to function as UE 110 (fig. 1). The UE 400 may include physical layer circuitry 402 to transmit signals to the eNB 104 (fig. 1) and receive signals from the eNB 104 using one or more antennas 401. The UE 400 may also include a medium access control layer (MAC) circuitry 404 to control access to the wireless medium. The UE 400 may also include processing circuitry 406 and memory 408 arranged to perform the operations described herein. According to an embodiment, the UE 400 may be arranged to receive Network Assistance (NA) Interference Cancellation Signaling (ICS) (NA-ICS) side information from the eNB for performing the interference mitigation discussed above.

In some embodiments, the UE 400 may be part of a portable wireless communication device: for example, a Personal Digital Assistant (PDA), a laptop or portable computer with wireless communication capability, a web tablet, a wireless telephone, a smartphone, a wireless headset, a pager, an instant messaging device, a digital camera, an access point, a television, a medical device (e.g., a heart rate monitor, a blood pressure monitor, etc.), or other device that may receive and/or transmit information wirelessly. In some embodiments, the UE 400 may include one or more of the following: a keyboard, a display, a non-volatile memory port, multiple antennas, a graphics processor, an application processor, speakers, and other mobile device elements. The display may be an LCD screen including a touch screen.

The one or more antennas 401 utilized by the UE 400 may include one or more directional or omnidirectional antennas, including, for example, dipole antennas, monopole antennas, patch antennas (patch antennas), loop antennas (loopantennas), microstrip antennas or other types of antennas suitable for transmission of RF signals. In some embodiments, instead of two or more antennas, a single antenna with multiple apertures may be used. In these embodiments, each aperture may be considered a separate antenna. In some multiple-input multiple-output (MIMO) embodiments, antennas may be effectively separated to take advantage of spatial diversity and different channel characteristics that may result between each antenna and the antennas of a transmitting station. In some MIMO embodiments, the antennas may be separated by up to 1/10 wavelengths or more.

Although the UE 400 is illustrated as having several separate functional elements, one or more of the functional elements may be combined and may be implemented by combinations of software-configured elements, such as processing elements including Digital Signal Processors (DSPs), and/or other hardware elements. For example, some elements may comprise one or more microprocessors, DSPs, Application Specific Integrated Circuits (ASICs), Radio Frequency Integrated Circuits (RFICs), and combinations of various hardware and logic circuitry for performing at least the functions described herein. In some embodiments, a functional element may refer to one or more processing elements operating on one or more processing elements.

Embodiments may be implemented in one or a combination of hardware, firmware, and software. Embodiments may also be implemented as instructions stored on a computer-readable storage medium, which may be read and executed by at least one processor to perform the operations described herein. A computer-readable storage medium may include any non-transitory mechanism for storing information in a form readable by a machine (e.g., a computer). For example, a computer-readable storage medium may include Read Only Memory (ROM), Random Access Memory (RAM), magnetic disk storage media, optical storage media, flash memory devices, and other storage devices and media. In these embodiments, one or more processors of UE 400 may be configured with instructions to perform the operations described herein.

In some embodiments, the UE 400 may be configured to receive OFDM communication signals over a multicarrier communication channel in accordance with an OFDMA communication technique. The OFDM signal may include a plurality of orthogonal subcarriers. In some broadband multicarrier embodiments, the eNB may be part of a Broadband Wireless Access (BWA) network communication network: such as a Worldwide Interoperability for Microwave Access (WiMAX) communication network or a third generation partnership project (3GPP) Universal Terrestrial Radio Access Network (UTRAN) Long Term Evolution (LTE) or Long Term Evolution (LTE) communication network, although the scope of the invention is not limited in this respect. In these wideband multicarrier embodiments, the UE 400 and eNB may be configured to communicate in accordance with Orthogonal Frequency Division Multiple Access (OFDMA) techniques.

In some LTE embodiments, the basic unit of radio resources is a Physical Resource Block (PRB). A PRB may include 12 subcarriers in the frequency domain x 0.5ms in the time domain. PRBs may be allocated in pairs (in the time domain). In these embodiments, the PRB may include a plurality of Resource Elements (REs). The RE may include one subcarrier × one symbol.

The eNB may transmit two types of reference signals including demodulation reference signals (DM-RS), channel state information reference signals (CIS-RS), and/or Common Reference Signals (CRS). The DM-RS may be used by the UE for data demodulation. The reference signal may be transmitted in a predetermined PRB.

In some embodiments, the OFDMA technique may be one of a Frequency Domain Duplexing (FDD) technique using different uplink and downlink frequency spectrums or a Time Domain Duplexing (TDD) technique using the same frequency spectrum for uplink and downlink.

In some other embodiments, UE 400 and eNB may be configured to transmit signals transmitted using one or more other modulation techniques, such as spread spectrum modulation (e.g., direct sequence code division multiple access (DS-CDMA) and/or frequency hopping code division multiple access (FH-CDMA)), Time Division Multiplexing (TDM) modulation, and/or Frequency Division Multiplexing (FDM) modulation, although the scope of the embodiments is not limited in this respect.

In some LTE embodiments, the UE 400 may calculate several different feedback values that may be used to perform channel adaptation for the closed-loop spatial multiplexing transmission mode. These feedback values may include a Channel Quality Indicator (CQI), a Rank Indicator (RI), and a Precoding Matrix Indicator (PMI). With the CQI, the transmitter selects one of several modulation symbol sets and coding rate combinations. The RI informs the transmitter about the number of useful transport layers of the current MIMO channel, and the PMI indicates a codebook index of a precoding matrix applied at the transmitter (depending on the number of transmit antennas). The coding rate used by the eNB may be based on the CQI. The PMI may be a vector calculated by the UE and reported to the eNB. In some embodiments, the UE may send a Physical Uplink Control Channel (PUCCH) containing CQI/PMI or RI in format 2, 2a, or 2 b.

In these embodiments, the CQI may be an indication of the downlink mobile radio channel quality experienced by the UE 400. The CQI allows the UE 400 to propose to the eNB the best modulation scheme and coding rate to use for a given radio link quality so that the resulting transport block error rate will not exceed a certain value (e.g., 10%). In some embodiments, the UE may report a wideband CQI value, which refers to the channel quality of the system bandwidth. The UE may also report a subband CQI value for each subband of a particular number of resource blocks that may be configured by higher layers. The complete set of sub-bands may cover the system bandwidth. In the case of spatial multiplexing, the CQI for each codeword may be reported.

In some embodiments, the PMI may indicate an optimal precoding matrix to be used by the eNB for given radio conditions. The PMI value refers to a codebook table. The network configures the number of resource blocks represented by the PMI report. In some embodiments, to cover system bandwidth, multiple PMI reports may be provided. PMI reports may also be provided for closed-loop spatial multiplexing, multi-user MIMO, and closed-loop rank 1 precoding MIMO modes.

In some coordinated multipoint (CoMP) embodiments, a network may be configured for joint transmission to a UE, where two or more cooperating/cooperating points (e.g., Remote Radio Heads (RRHs)) transmit jointly. In these embodiments, the joint transmission may be a MIMO transmission and the cooperating points are configured to perform joint beamforming.

The abstract is provided to comply with section 37 c.f.r 1.72(b), which requires an abstract that will allow the reader to ascertain the nature and gist of the technical disclosure. It is submitted with the understanding that it will not be used to limit or interpret the scope or meaning of the claims. The following claims are hereby incorporated into the detailed description, with each claim standing on its own as a separate embodiment.

Claims (24)

1. An apparatus of a User Equipment (UE), the apparatus comprising a memory and processing circuitry configured to:

encoding Radio Resource Control (RRC) signaling for transmission to an enhanced node B (eNB), the RRC signaling indicating that the UE supports network assisted interference cancellation mitigation (NAICS);

decoding RRC signaling received from the eNB to determine neighbor cell information for the NAICS, the neighbor cell information including cell Identifications (IDs) and one or more Transmission Modes (TMs) of neighbor cells; and

performing interference mitigation techniques to eliminate or suppress interference based on neighbor cell information of the NAICS.

2. The apparatus of claim 1, wherein the processing circuitry is further configured to: decoding RRC signaling received from the eNB to determine cell-specific reference signal (CRS) information for use in performing the interference mitigation technique.

3. The apparatus of claim 2, wherein the processing circuitry is further configured to:

decoding RRC signaling received from the eNB to determine whether codebook subset restrictions apply to a transmission mode to be used by the UE.

4. The apparatus of claim 3, wherein the codebook subset restriction is configured to restrict transmission options of the UE that are restricted to reduce co-channel cell interference with the neighboring cell.

5. The apparatus of claim 1, wherein the processing circuitry is further configured to: decoding RRC signaling received from the eNB to determine whether codebook subset restrictions apply to transmission modes used within the neighboring cell.

6. The apparatus of claim 1, wherein the neighbor cell information of the NAICS further includes a modulation order and encoder information, and

wherein the processing circuitry includes maximum likelihood detection circuitry to demodulate interfering signals falling within resource blocks allocated to the UE based on the modulation order and precoder information.

7. The apparatus of claim 1, wherein the RRC signaling received from the eNB to determine neighbor cell information for the NAICS is transmitted using a signaling codebook.

8. The apparatus of claim 7, wherein the signaling codebook is a subset of a master signaling codebook.

9. The apparatus of claim 7, wherein subsequent RRC signaling received from the eNB to determine neighbor cell information for the NAICS is conveyed differently for the signaling codebook.

10. The apparatus of claim 7, wherein the one or more transmission modes comprise transmission options comprising: modulation and multiplexing options, transmission rank, and antenna configuration options.

11. The apparatus of claim 10, wherein the one or more transmission modes are transmission modes of a plurality of transmission modes defined by the signaling codebook, and

wherein the transmission options for the one or more transmission modes are defined by a subset of the signaling codebook.

12. The apparatus of claim 1, wherein the RRC signaling for transmission to the eNB to indicate the UE supports NAICS is transmitted via uplink control information on a Physical Uplink Control Channel (PUCCH), and

wherein the RRC signaling is received via Downlink Control Information (DCI) on a Physical Downlink Control Channel (PDCCH).

13. A non-transitory computer-readable storage medium having instructions stored thereon for execution by processing circuitry of a User Equipment (UE) to configure the UE to:

encoding Radio Resource Control (RRC) signaling for transmission to an enhanced node B (eNB), the RRC signaling indicating that the UE supports network assisted interference cancellation/suppression (NAICS);

decoding RRC signaling received from the eNB to determine neighbor cell information for the NAICS, the neighbor cell information including cell-specific reference signal (CRS) information for neighbor cells; and

performing interference mitigation techniques to eliminate or suppress interference based on neighbor cell information of the NAICS.

14. The non-transitory computer-readable storage medium of claim 13, wherein the processing circuit is further configured to: decoding RRC signaling received from the eNB to determine one or more Transmission Modes (TMs) of the neighboring cell for use in performing the interference mitigation technique.

15. The non-transitory computer-readable storage medium of claim 14, wherein the processing circuit is further configured to:

decoding RRC signaling received from the eNB to determine whether codebook subset restrictions apply to a transmission mode to be used by the UE.

16. The non-transitory computer-readable storage medium of claim 15, wherein the codebook subset restriction is configured to restrict transmission options of the UE that are restricted to reduce co-channel cell interference with the neighboring cell.

17. The non-transitory computer readable storage medium of claim 13, wherein the processing circuit is further configured to: decoding RRC signaling received from the eNB to determine whether codebook subset restrictions apply to transmission modes used within the neighboring cell.

18. The non-transitory computer-readable storage medium of claim 13, wherein the RRC signaling received from the eNB to determine neighbor cell information for the NAICS is transmitted using a signaling codebook that is a subset of a primary signaling codebook.

19. An apparatus of an enhanced node b (enb), the apparatus comprising memory and processing circuitry configured to:

decoding Radio Resource Control (RRC) signaling received from a User Equipment (UE), the RRC signaling indicating that the UE supports network assisted interference cancellation/suppression (NAICS);

in response to the indication that the UE supports NAICS, encoding RRC signaling for transmission to the UE to indicate neighbor cell information of the NAICS, the neighbor cell information including cell Identifications (IDs) and one or more Transmission Modes (TMs) of neighbor cells.

20. The apparatus of claim 19, wherein the processing circuitry is further configured to:

encoding signaling to limit a transmission mode of a UE operating in the neighboring cell to mitigate co-channel interference with the UE.

21. The apparatus of claim 19, wherein the processing circuitry is further configured to:

encoding signaling transmitted to the UE to limit a transmission mode of the UE to mitigate co-channel interference with UEs operating in the neighboring cell.

22. The apparatus of claim 21, wherein the signaling for restricting the transmission mode of the UE is transmitted with a signaling codebook that is a subset of a master signaling codebook.

23. The apparatus of claim 19, wherein the processing circuitry is configured to: selecting neighbor cell information for the NAICS to allow the UE to perform interference mitigation techniques to cancel or suppress interference.

24. The apparatus of claim 19, wherein the processing circuitry is configured to: encoding RRC signaling for transmission to the UE to provide cell-specific reference signal (CRS) information for use by the UE in performing the interference mitigation technique.