WO2015071535A1

WO2015071535A1 - Power back-off arrangement and channel state information reporting to support higher order modulation

Info

Publication number: WO2015071535A1
Application number: PCT/FI2014/050844
Authority: WO
Inventors: Klaus Hugl; Cassio Ribeiro; Pekka JÄNIS
Original assignee: Nokia Technologies Oy
Priority date: 2013-11-12
Filing date: 2014-11-11
Publication date: 2015-05-21

Abstract

Systems, methods, apparatuses, and computer program products for power back-off aware CSI reporting and/or PDSCH decoding are provided. One method includes defining, by a network node, an additional configurable parameter that may be configured jointly with 256QAM DL operation. The method may further include signaling the additional configurable parameter to at least one UE. The value of the additional configurable parameter, for example, may provide the power offset for the at least one UE, for example, to assume in CSI reporting and/or for PDSCH decoding.

Description

POWER BACK-OFF ARRANGEMENT AND CHANNEL STATE INFORMATION REPORTING TO SUPPORT HIGHER ORDER MODULATION

CROSS-REFERENCE TO RELATED APPLICATIONS:

This application claims priority from United States Provisional Application No. 61/903,136, filed on November 12, 2013. The entire contents of this earlier filed application are hereby incorporated by reference in their entirety.

BACKGROUND:

Field:

Some embodiments of the invention generally relate to mobile communications networks, such as, but not limited to, the Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (UTRAN), Long Term Evolution (LTE) Evolved UTRAN (E-UTRAN), and/or LTE-A.

Description of the Related Art:

Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (UTRAN) refers to a communications network including base stations, or Node Bs, and for example radio network controllers (RNC). UTRAN allows for connectivity between the user equipment (UE) and the core network. The RNC provides control functionalities for one or more Node Bs. The RNC and its corresponding Node Bs are called the Radio Network Subsystem (RNS). In case of E-UTRAN (enhanced UTRAN), no RNC exists and most of the RNC functionalities are contained in the evolved Node B (eNodeB or eNB).

Long Term Evolution (LTE) or E-UTRAN refers to improvements of the UMTS through improved efficiency and services, lower costs, and use of new spectrum opportunities. In particular, LTE is a 3rd generation partnership project (3GPP) standard that provides for uplink peak rates of at least 50 megabits per second (Mbps) and downlink peak rates of at least 100 Mbps. LTE supports scalable carrier bandwidths from 20 MHz down to 1.4 MHz and supports both Frequency Division Duplexing (FDD) and Time Division Duplexing (TDD). As mentioned above, LTE may also improve spectral efficiency in networks, allowing carriers to provide more data and voice services over a given bandwidth. Therefore, LTE is designed to fulfill the needs for high-speed data and multimedia transport in addition to high-capacity voice support. Advantages of LTE include, for example, high throughput, low latency, FDD and TDD support in the same platform, an improved end-user experience, and a simple architecture resulting in low operating costs.

Further releases of 3GPP LTE (e.g., LTE Rel-10, LTE Rel-1 1, LTE Rel-12) are targeted towards future international mobile telecommunications advanced (IMT-A) systems, referred to herein for convenience simply as LTE-Advanced (LTE-A).

LTE-A is directed toward extending and optimizing the 3 GPP LTE radio access technologies. A goal of LTE-A is to provide significantly enhanced services by means of higher data rates and lower latency with reduced cost. LTE-A will be a more optimized radio system fulfilling the international telecommunication union- radio (ITU-R) requirements for IMT-Advanced while keeping the backward compatibility.

SUMMARY:

One embodiment is directed to an apparatus including at least one processor and at least one memory including computer program code. The at least one memory and computer program code may be configured, with the at least one processor, to cause the apparatus at least to define an additional higher layer configurable parameter that is configured jointly with 256 quadrature amplitude modulation (256QAM) downlink (DL) operation, and to send the additional higher layer configurable parameter to at least one user equipment. A value of the additional higher layer configurable parameter provides a power offset for the user equipment to assume in channel state information (CSI) reporting or for physical downlink shared channel (PDSCH) decoding of at least cell-specific reference signals (CRS) based transmissions and/or demodulation reference signals (DM-RS) based transmissions. According to one embodiment, the apparatus may be an eNB.

In an embodiment, the value of the additional higher layer configurable parameter further provides a power offset for the user equipment to assume in demodulation reference signals (DM- S) based physical downlink shared channel (PDSCH) transmissions. According to one embodiment, the additional higher layer configurable parameter may be P_256QAM_offset.

According to certain embodiments, the at least one memory and computer program code may be configured, with the at least one processor, to cause the apparatus at least to receive a channel quality indicator (CQI) report from the user equipment, where the received CQI report takes into account the power offset indicated by the value of the additional higher layer configurable parameter. In some embodiments, the at least one memory and computer program code may be configured, with the at least one processor, to cause the apparatus at least to perform scheduling and link/rank/precoder adaptation taking into account the power offset.

In an embodiment, the at least one memory and computer program code may be configured, with the at least one processor, to cause the apparatus at least to use the power offset when transmitting the physical downlink shared channel (PDSCH) to the user equipment using 256QAM.

Another embodiment is directed to a method. The method may include defining, by a network node, an additional higher layer configurable parameter that is configured jointly with 256 quadrature amplitude modulation (256QAM) downlink (DL) operation. The method may also include sending the additional higher layer configurable parameter to at least one user equipment, where a value of the additional higher layer configurable parameter provides a power offset for the user equipment to assume in channel state information (CSI) reporting or for physical downlink shared channel (PDSCH) decoding of at least cell-specific reference signals (CRS) based transmissions and/or demodulation reference signals (DM-RS) based transmissions. In one embodiment, the value of the additional higher layer configurable parameter further provides a power offset for the user equipment to assume in demodulation reference signals (DM- S) based physical downlink shared channel (PDSCH) transmissions. In some embodiments, the additional higher layer configurable parameter may be P_256QAM_offset.

According to certain embodiments, the method may further include receiving a channel quality indicator (CQI) report from the user equipment, where the received CQI report takes into account the power offset indicated by the value of the additional higher layer configurable parameter. The method may also include, in an embodiment, performing scheduling and link/rank/precoder adaptation taking into account the power offset. In some embodiments, the method may also include using the power offset when transmitting the physical downlink shared channel (PDSCH) to the user equipment using 256QAM.

Another embodiment is directed to an apparatus including means for defining, by a network node, an additional higher layer configurable parameter that is configured jointly with 256 quadrature amplitude modulation (256QAM) downlink (DL) operation. The apparatus may also include means for sending the additional higher layer configurable parameter to at least one user equipment, where a value of the additional higher layer configurable parameter provides a power offset for the user equipment to assume in channel state information (CSI) reporting or for physical downlink shared channel (PDSCH) decoding of at least cell-specific reference signals (CRS) based transmissions and/or demodulation reference signals (DM-RS) based transmissions.

Another embodiment is directed to a computer program, embodied on a computer readable medium, the computer program is configured to control a processor to perform a process including defining an additional higher layer configurable parameter that is configured jointly with 256 quadrature amplitude modulation (256QAM) downlink (DL) operation. The process may also include sending the additional higher layer configurable parameter to at least one user equipment, where a value of the additional higher layer configurable parameter provides a power offset for the user equipment to assume in channel state information (CSI) reporting or for physical downlink shared channel (PDSCH) decoding of at least cell-specific reference signals (C S) based transmissions and/or demodulation reference signals (DM-RS) based transmissions.

Another embodiment is directed to an apparatus including at least one processor and at least one memory including computer program code. The at least one memory and computer program code may be configured, with the at least one processor, to cause the apparatus at least to receive an additional higher layer configurable parameter that is configured jointly with 256 quadrature amplitude modulation (256QAM) downlink (DL) operation, and to use a value of the additional higher layer configurable parameter as a power offset to assume in channel state information (CSI) reporting or for physical downlink shared channel (PDSCH) decoding of at least cell-specific reference signals (CRS) based transmissions and/or demodulation reference signals (DM-RS) based transmissions. In an embodiment, the apparatus may be a user equipment.

In some embodiments, the value of the additional higher layer configurable parameter is further used as a power offset to assume in demodulation reference signals (DM-RS) based physical downlink shared channel (PDSCH) transmissions. In one embodiment, the additional higher layer configurable parameter may be P_256QAM_offset.

According to certain embodiment, the at least one memory and computer program code may be configured, with the at least one processor, to cause the apparatus at least to send a channel quality indicator (CQI) report to an evolved node B (eNB), where the CQI report takes into account the power offset indicated by the value of the additional higher layer configurable parameter.

Another embodiment is directed to a method. The method may include receiving, by a user equipment, an additional higher layer configurable parameter that is configured jointly with 256 quadrature amplitude modulation (256QAM) downlink (DL) operation. The method may further include using a value of the additional higher layer configurable parameter as a power offset to assume in channel state information (CSI) reporting or for physical downlink shared channel (PDSCH) decoding of at least cell-specific reference signals (C S) based transmissions and/or demodulation reference signals (DM-RS) based transmissions.

In an embodiment, the value of the additional higher layer configurable parameter may further be used as a power offset to assume in demodulation reference signals (DM-RS) based physical downlink shared channel (PDSCH) transmissions. According to one embodiment, the additional higher layer configurable parameter may be P_256QAM_offset.

According to certain embodiments, the method may also include sending a channel quality indicator (CQI) report to an evolved node B (eNB), where the CQI report takes into account the power offset indicated by the value of the additional higher layer configurable parameter.

Another embodiment is directed to an apparatus including means for receiving, by a user equipment, an additional higher layer configurable parameter that is configured jointly with 256 quadrature amplitude modulation (256QAM) downlink (DL) operation. The apparatus may further include means for using a value of the additional higher layer configurable parameter as a power offset to assume in channel state information (CSI) reporting or for physical downlink shared channel (PDSCH) decoding of at least cell-specific reference signals (CRS) based transmissions and/or demodulation reference signals (DM-RS) based transmissions.

Another embodiment is directed to a computer program, embodied on a computer readable medium, the computer program is configured to control a processor to perform a process including receiving an additional higher layer configurable parameter that is configured jointly with 256 quadrature amplitude modulation (256QAM) downlink (DL) operation. The process may further include using a value of the additional higher layer configurable parameter as a power offset to assume in channel state information (CSI) reporting or for physical downlink shared channel (PDSCH) decoding of at least cell-specific reference signals (CRS) based transmissions and/or demodulation reference signals (DM-RS) based transmissions.

BRIEF DESCRIPTION OF THE DRAWINGS:

For proper understanding of the invention, reference should be made to the accompanying drawings, wherein:

Fig. la illustrates an example operation of PDSCH modulation independent power back-off operation;

Fig. lb illustrates an example of efficient power back-off operation being PDSCH modulation dependent, with a specific time domain power adaptation example of the PDSCH area to enable power-back-off for 256QAM PDSCH, according to an embodiment;

Fig. 2 illustrates an apparatus according to one embodiment;

Fig. 3a illustrates an apparatus according to an embodiment;

Fig. 3b illustrates an apparatus according to another embodiment;

Fig. 4 illustrates a flow diagram of a method according to one embodiment; and

Fig. 5 illustrates a flow diagram of a method according to another embodiment.

DETAILED DESCRIPTION:

It will be readily understood that the components of the invention, as generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of systems, methods, apparatuses, and computer program products for power back-off aware channel state information (CSI) reporting and/or physical downlink shared channel (PDSCH) decoding, as represented in the attached figures, is not intended to limit the scope of the invention, but is merely representative of selected embodiments of the invention.

The features, structures, or characteristics of the invention described throughout this specification may be combined in any suitable manner in one or more embodiments. For example, the usage of the phrases "certain embodiments," "some embodiments," or other similar language, throughout this specification refers to the fact that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the present invention. Thus, appearances of the phrases "in certain embodiments," "in some embodiments," "in other embodiments," or other similar language, throughout this specification do not necessarily all refer to the same group of embodiments, and the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. Additionally, if desired, the different functions discussed below may be performed in a different order and/or concurrently with each other. Furthermore, if desired, one or more of the described functions may be optional or may be combined. As such, the following description should be considered as merely illustrative of the principles, teachings and embodiments of this invention, and not in limitation thereof.

As part of the "Small Cell Enhancements - Physical Layer" study item in 3GPP, the introduction of downlink (DL) 256 quadrature amplitude modulation (256QAM) for the physical downlink shared channel (PDSCH) is currently being discussed. This is in order to improve the DL spectral efficiency for terminals/UEs being in very favorable signal conditions, i.e., being close to the small cell eNB/base station.

The studies in 3GPP have shown that it is important to transmit the 256QAM signal with as little distortion as possible in order to be able to reliably detect the signals using such higher order modulation. The distortion at the transmitter given by the transmitter error vector magnitude (EVM) should be lower for 256QAM modulation when compared with lower order modulation (such as QPSK, 16QAM and 64QAM). It had been noted that the EVM of a small cell/low power eNB can achieve the low transmitter distortions required for 256QAM at a cost of needed additional clipping or some power back-off to be applied.

It is clear that, if there is a nominal output power of a small cell eNB (referred to herein as P nom), in order to achieve a lower transmitter distortion/EVM, the transmission power in case of 256QAM modulation might need be lowered by some power back-off (referred to herein as P back off). One option for the eNB may be to reduce the DL transmission (Tx) power in general to a lower value in order to support 256QAM, i.e., all DL channels and signals (including, for example, PDSCH, PDCCH, PSS, SSS, PBCH, and C S) independently of the used modulation would use the lower output power considering the power back-off (P nom-P back off). This is illustrated in Fig. la, which depicts such an example. However, by implementing this operation mode, the coverage of the eNB would be sacrificed, as indicated by the grey striped area in Fig. la, due to the overall applied power back-off. So reducing DL Tx power for all DL channels and signals is a rather suboptimal solution, as it will affect the coverage of UEs not being 256QAM PDSCH capable in general (including all the legacy devices) as well as affecting the coverage and performance for 256QAM capable UEs in channel conditions unfavorable for utilization of 256QAM modulation.

A more optimal operation mode for the eNB would be to allow the eNB to transmit other than 256QAM modulations (e.g., QPSK, 16QAM & 64QAM) with the nominal Tx power P nom (e.g., 20 or 24dBm) so as not to sacrifice the coverage of the eNB/base station as such, but also allow it to reduce the transmission power of the 256QAM PDSCH to P_256QAM=(P_nom-P_back_off) on logarithmic scale (dB/dBm) in a UE specific manner in order to serve a UE with 256QAM. As shown by recent studies in 3GPP, in case of small cell deployments, often only a single UE is served by an eNB at a time, which makes such DL transmission power adaptations possible. So the transmission power reduction would be done in time domain for the PDSCH part of subframes where PDSCH with 256QAM is transmitted. This is illustrated in Fig. lb, which depicts an example of time domain power adaptation to enable power-backoff for 256QAM PDSCH. As can been seen from Fig. lb compared to Fig. la, the coverage and related performance is not negatively affected for the physical downlink control channel (PDCCH) as well as for PDSCH area of subframes where no 256QAM is applied. Moreover, the operation as such is not limited to having all PDSCHs (independent of their modulation) transmitted with the lower power in subframes where some PDSCH with 256QAM is used. In case of low load not requiring all the available PDSCH resources, some limited frequency domain multiplexing of PDSCHs not using 256QAM with higher transmission power and PDSCHs using 256QAM using lower transmission power is possible as long as the overall maximum transmission power in the PDSCH area of that subframe is not exceeding [P nom-P back off] required for 256QAM PDSCH operation. Therefore, limited frequency domain multiplexing of non-256QAM PDSCHs and 256QAM PDSCH is also possible in this output power optimized operation mode.

Such a variation of PDSCH transmit power depending on the applied modulation has an impact on the channel state information (CSI)/channel quality indicator (CQI) reporting procedure. This is because the UE creates the CSI report based on its understanding of received signal power, as well as other channel parameters. Accordingly, embodiments of the invention provide an optimized CSI/CQI reporting that supports an operation mode where transmit power is varied depending on the applied modulation.

Currently, the UE assumes a certain energy per resource element (EP E) in the CSI reporting and the corresponding CQI definition, given in Sec. 7.2.3 of 3GPP TS 36.213. The power difference between the reference signals used for CSI measurements and the PDSCH is given in Sec. 7.2.3 of 3GPP TS 36.213 as the following:

• If CRS is used for channel measurements, the ratio of PDSCH EPRE to cell-specific RS EPRE is as given in Section 5.2 [of 3GPP TS 36.213] with the exception of p_A which shall be assumed to be o P_A = P_A ⁺ _0ffSet + 10 log_w (2) [dB] for any modulation scheme, if the

UE is configured with transmission mode 2 with 4 cell-specific antenna ports, or transmission mode 3 with 4 cell-specific antenna ports and the associated RI is equal to one;

o p_A = P_A + A₀ff_set [dB] for any modulation scheme and any number of layers, otherwise.

The shift A₀g_set is given by the parameter nomPDSCH-RS-EPRE-Offset which is configured by higher-layer signalling.

• If CSI-RS is used for channel measurements, the ratio of PDSCH EPRE to CSI-RS EPRE is as given in Section 7.2.5.

Section 7.2.5 of 3GPP TS 36.213 states:

• P_c is the assumed ratio of PDSCH EPRE to CSI-RS EPRE when UE derives CSI feedback and takes values in the range of [-8, 15] dB with 1 dB step size, where the PDSCH EPRE corresponds to the symbols for which the ratio of the PDSCH EPRE to the cell-specific RS EPRE is denoted by p_A, as specified in Table 5.2-2 and Table 5.2-3 [of 3GPP TS 36.213].

As is clear from the above outlined 3GPP specifications, the UE assumes the same nominal PDSCH transmission power (i.e., energy per resource element, PDSCH EPRE) independent of the applied modulation format in its CQI calculation and CSI reporting. This in general may work fine, but as the eNB might need to reduce its transmission power (i.e., PDSCH EPRE) for 256QAM modulations only, the reported CQI in case of 256QAM compared to the 64QAM cases will not be really usable at the eNB, assuming the eNB would optimize its operation overall as stated above and as illustrated in Fig. lb.

Moreover, the PDSCH to CRS EPRE is needed in order to demodulate higher-order modulation for CRS based transmission modes. This DL power offset/control is given in general in Sec. 5.2 of 3GPP TS 36.213:

The ratio of PDSCH EPRE to cell-specific RS EPRE among PDSCH REs (not applicable to PDSCH REs with zero EPRE) for each OFDM symbol is denoted by either p_A or p_B according to the OFDM symbol index as given by Table 5.2-2 and Table 5.2-3. In addition, p_A and p_B are UE-specific.

For a UE in transmission mode 8 or 9 when UE-specific RSs are not present in the PRBs upon which the corresponding PDSCH is mapped or in transmission modes 1 - 7, the UE may assume that for 16 QAM, 64 QAM, spatial multiplexing with more than one layer or for PDSCH transmissions associated with the multi-user MIMO transmission scheme,

• p_A is equal to<5_power__offset + P_A + 101og₁₀(2) [dB] when the UE receives a

PDSCH data transmission using precoding for transmit diversity with 4 cell-specific antenna ports according to Section 6.3.4.3 of [3J;

• _Pa is equal to <5_power__offset + P_A [ dB] otherwise where <5_power__offset is 0 dB for all PDSCH transmission schemes except multiuser MIMO and where P_A is a UE specific parameter provided by higher layers.

In case a different Tx power is used due to power back-off dynamically when applying 256QAM formulation, this would need to be informed by the eNB to the UE as well for the PDSCH decoding process of at least transmission modes using cell-specific reference signals (C S).

According to certain embodiments, one additional higher layer configurable parameter (e.g., P_256QAM_offset) is added. In an embodiment, this higher layer configurable parameter may be configured jointly with the 256QAM DL operation in general. The value of the higher layer configurable parameter can provide the power offset for the UE to be assumed in the CSI reporting between legacy modulation orders (e.g., QPSK, 16QAM and 64QAM) and 256QAM. Therefore, this higher layer configurable parameter may be included in the parts of 3 GPP TS 36.213 discussed above (i.e., the PDSCH EPRE assumption for CSI reporting would be in addition modulation order specific). This higher layer configurable parameter or a similar separate one could be of course envisioned for any kind of future introduction of even higher modulation orders (e.g. 1024QAM etc.).

In addition, the same higher layer configurable parameter (P_256QAM_offset) may be included in the DL power control information the UE assumes for CRS based transmission modes in Sec. 5.2 of 3GPP TS 36.213, which is also discussed above. More specifically, there may need to be separate clauses for 256QAM which are different from the cases of 16QAM and 64QAM including the higher layer configurable parameter (P_256QAM_offset) for 256QAM.

For demodulation reference signals (DM-RS) based transmission modes, where the DM-RS/UE-specific RS is present in the physical resource blocks (PRBs), the DM-RS/UE-specific RS power also directly reflects the PDSCH power for 16QAM and 64QAM. Accordingly, in an embodiment, this can be extended to 256QAM PDSCH operation, i.e., the DM-RS power would also be reduced by power back-off for 256QAM PDSCH. Alternatively, in another embodiment, the offset parameter P_256QAM_offset could be also applied to the ratio of DM-RS and 256QAM PDSCH, for example to avoid degradation on the channel estimation performance in PDSCH when using 256QAM modulation.

Therefore, one embodiment defines a new higher layer configurable parameter, for example P_256QAM_offset, that is configured jointly with the 256QAM DL operation by the network. According to certain embodiments, the UE takes this parameter into account in CSI reporting for all transmission modes (for CRS-based transmission modes - i.e., TM1-6, as well as UE-specific RS/DM-RS based transmission modes TM7-10). For example, in the case where the UE creates the report by choosing the modulation and coding scheme (MCS), rank, and precoder that gives highest throughput with current channel conditions, the UE will take into account P_256QAM_offset when comparing 256QAM MCS options to 64QAM MCS options. Such operation may impact not only the exact MCS selection but also the rank and corresponding precoder reporting.

Further, in certain embodiments, the UE can take this new higher layer configurable parameter into account in PDSCH decoding of transmission modes (TM1-7) as well as in P Bs of TM8-10 where UE-specific RS/DM-RS is not present. In addition, in other embodiments, the UE can take this new higher layer configurable parameter into account in PDSCH decoding of PRBs of TM8-10 where other kind of reference signal such as for example UE-specific RS/DM-RS is present.

The introduction of this higher layer signaled parameter, as discussed above, makes it possible for the eNB to operate dynamically with different output power for legacy DL modulations and a lower power due to the needed power backoff for 256QAM, without sacrificing the eNB baseline coverage as such and optimize the CSI/CQI reporting for this case.

Since one of the main reasons for power back-off in connection with 256QAM is to reduce the amount of EVM in the DL signal, in one embodiment, the UE takes into account the reduction in EVM when computing the CSI report. For example, according to an embodiment, in the case where the UE is able to estimate the power of dominant interferers directly, it can estimate how much of the interference it observes is due to EVM and it can take this into account when computing the CSI report. Alternatively, the UE might use heuristic methods to estimate the contribution from EVM, for example based on the eNB transmitter requirements. Optionally, the eNB could signal this information explicitly.

Fig. 2 illustrates an example of an apparatus 100 according to this embodiment. In one example, apparatus 100 may be a UE as discussed above. Apparatus 100 may include, for example, an estimating unit 105 configured to estimate the amount of interference that apparatus 100 observes which is due to EVM originated by transmissions from the eNB or eNBs transmitting the reference signals used to measure the CSI. Apparatus 100 may further include a computing unit 1 10 configured to compute the CSI report while taking into account the amount of interference that the estimating unit 105 estimates is due to EVM originated by transmissions from the eNB or eNBs transmitting the reference signals used to measure the CSI. Fig. 3a illustrates an example of an apparatus 20 according to another embodiment. In an embodiment, apparatus 20 may be a network node in a communications network, such as a base station or an eNB in LTE. It should be noted that one of ordinary skill in the art would understand that apparatus 20 may include components or features not shown in Fig. 3a. Only those components or features necessary for illustration of the invention are depicted in Fig. 3a.

As illustrated in Fig. 3a, apparatus 20 includes a processor 32 for processing information and executing instructions or operations. Processor 32 may be any type of general or specific purpose processor. While a single processor 32 is shown in Fig. 3a, multiple processors may be utilized according to other embodiments. In fact, processor 32 may include one or more of general-purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), field- programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), and processors based on a multi-core processor architecture, as examples.

Apparatus 20 further includes a memory 34, which may be coupled to processor 32, for storing information and instructions that may be executed by processor 32. Memory 34 may be one or more memories and of any type suitable to the local application environment, and may be implemented using any suitable volatile or nonvolatile data storage technology such as a semiconductor-based memory device, a magnetic memory device and system, an optical memory device and system, fixed memory, and removable memory. For example, memory 34 can be comprised of any combination of random access memory (RAM), read only memory (ROM), static storage such as a magnetic or optical disk, or any other type of non-transitory machine or computer readable media. The instructions stored in memory 34 may include program instructions or computer program code that, when executed by processor 32, enable the apparatus 20 to perform tasks as described herein.

Apparatus 20 may also include one or more antennas 35 for transmitting and receiving signals and/or data to and from apparatus 20. Apparatus 20 may further include a transceiver 38 configured to transmit and receive information. For instance, transceiver 38 may be configured to modulate information on to a carrier waveform for transmission by the antenna(s) 35 and demodulate information received via the antenna(s) 35 for further processing by other elements of apparatus 20. In other embodiments, transceiver 38 may be capable of transmitting and receiving signals or data directly.

Processor 32 may perform functions associated with the operation of apparatus 20 including, without limitation, precoding of antenna gain/phase parameters, encoding and decoding of individual bits forming a communication message, formatting of information, and overall control of the apparatus 20, including processes related to management of communication resources.

In an embodiment, memory 34 stores software modules that provide functionality when executed by processor 32. The modules may include, for example, an operating system that provides operating system functionality for apparatus 20. The memory may also store one or more functional modules, such as an application or program, to provide additional functionality for apparatus 20. The components of apparatus 20 may be implemented in hardware, or as any suitable combination of hardware and software.

Apparatus 20 may also include a power control unit 33, for instance a PDSCH power control unit. The power control unit 33 can be configured to perform the power adaptation according to embodiments of the invention. Apparatus 20 may also include a defining unit 37, for example, configured to perform the definition of the higher layer configurable parameter.

As mentioned above, according to one embodiment, apparatus 20 may be a network node in a communications network, such as a base station or an eNB in LTE. In this embodiment, apparatus 20 may be controlled by memory 34 and processor 32, for example via the defining unit 37, to define an additional higher layer configurable parameter that is configured jointly with 256QAM DL operation, and to send, for example via transceiver 38, the additional higher layer configurable parameter to at least one UE. In one embodiment, the value of the additional higher layer configurable parameter provides the power offset for the UE to assume in CSI reporting and/or for PDSCH decoding of at least CRS based and potentially also other kind of RS such as for example DM-RS based PDSCH transmissions.

Fig. 3b illustrates an example of an apparatus 10 according to an embodiment. In one embodiment, apparatus 10 may be a UE or mobile device. Further, it should be noted that one of ordinary skill in the art would understand that apparatus 10 may include components or features not shown in Fig. 3b. Only those components or features necessary for illustration of the invention are depicted in Fig. 3b.

As illustrated in Fig. 3b, apparatus 10 includes a processor 22 for processing information and executing instructions or operations. Processor 22 may be any type of general or specific purpose processor. While a single processor 22 is shown in Fig. 3b, multiple processors may be utilized according to other embodiments. In fact, processor 22 may include one or more of general-purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), field- programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), and processors based on a multi-core processor architecture, as examples.

Apparatus 10 further includes a memory 14, which may be coupled to processor 22, for storing information and instructions that may be executed by processor 22. Memory 14 may be one or more memories and of any type suitable to the local application environment, and may be implemented using any suitable volatile or nonvolatile data storage technology such as a semiconductor-based memory device, a magnetic memory device and system, an optical memory device and system, fixed memory, and removable memory. For example, memory 14 can be comprised of any combination of random access memory (RAM), read only memory (ROM), static storage such as a magnetic or optical disk, or any other type of non-transitory machine or computer readable media. The instructions stored in memory 14 may include program instructions or computer program code that, when executed by processor 22, enable the apparatus 10 to perform tasks as described herein.

Apparatus 10 may also include one or more antennas 25 for transmitting and receiving signals and/or data to and from apparatus 10. Apparatus 10 may further include a transceiver 28 configured to transmit and receive information. For instance, transceiver 28 may be configured to modulate information on to a carrier waveform for transmission by the antenna(s) 25 and demodulate information received via the antenna(s) 25 for further processing by other elements of apparatus 10. In other embodiments, transceiver 28 may be capable of transmitting and receiving signals or data directly.

Processor 22 may perform functions associated with the operation of apparatus 10 including, without limitation, precoding of antenna gain/phase parameters, encoding and decoding of individual bits forming a communication message, formatting of information, and overall control of the apparatus 10, including processes related to management of communication resources.

In an embodiment, memory 14 stores software modules that provide functionality when executed by processor 22. The modules may include, for example, an operating system that provides operating system functionality for apparatus 10. The memory may also store one or more functional modules, such as an application or program, to provide additional functionality for apparatus 10. The components of apparatus 10 may be implemented in hardware, or as any suitable combination of hardware and software.

In some embodiments, apparatus 10 may further include a calculating unit 24 and a decoding unit 26.

In one embodiment, apparatus 10 may be a UE or mobile device that may or may not be associated with a network. In this embodiment, apparatus 10 may be controlled by memory 14 and processor 22 to receive, for example via transceiver 28, an additional higher layer configurable parameter from the network. According to an embodiment, apparatus 10 may then be controlled by memory 14 and processor 22, via calculating unit 24, to calculate a CSI report for all transmission modes taking into account the received additional higher layer configurable parameter.

According to an embodiment, apparatus 10 may also be controlled by memory 14 and processor 22, via decoding unit 26, for PDSCH decoding where the received higher layer configurable parameter is also taken into account.

Fig. 4 illustrates an example flow diagram of a method according to one embodiment. In an embodiment, the method of Fig. 4 may be executed by a network node. The method may include, at 300, defining an additional higher layer configurable parameter that may be configured jointly with 256QAM DL operation. In an embodiment, the method may include, at 301, sending the higher layer configurable parameter to at least one UE. In some embodiments, the method may include, at 303, receiving a CQI report that has taken into account the power offset. Additionally or alternatively, in an embodiment, the method may include, at 304, performing scheduling and link/rank/precoder adaptation taking into account the power offset. The method may also include, at 305, using the power offset when transmitting PDSCH to the UE using 256QAM. In an embodiment, the value of the additional higher layer configurable parameter provides the power offset for the UE to assume in CSI reporting and/or for decoding of PDSCH transmissions.

Fig. 5 illustrates an example flow diagram of a method according to another embodiment. In an embodiment, the method of Fig. 5 may be executed by a UE associated with a network. The method includes, at 400, receiving an additional higher layer configurable parameter from the network. According to an embodiment, the method may further include, at 410, using the additional higher layer configurable parameter when estimating the CSI of a PDSCH. In an embodiment, the method may additionally or alternatively include, at 420, using the additional higher layer configurable parameter for PDSCH decoding.

In some embodiments, the functionality of any of the methods described herein, such as those illustrated in Figs. 4 or 5 discussed above, may be implemented by software and/or computer program code stored in memory or other computer readable or tangible media, and executed by a processor. In other embodiments, the functionality may be performed by hardware, for example through the use of an application specific integrated circuit (ASIC), a programmable gate array (PGA), a field programmable gate array (FPGA), or any other combination of hardware and software.

In view of the above, one embodiment includes a method of power back-off aware CSI reporting and/or PDSCH decoding. The method may include defining, by a network node, an additional configurable parameter that may be configured jointly with 256QAM DL operation. In some embodiments, the configurable parameter and 256QAM DL operation can be configured separately. The method may further include configuring the additional parameter for at least one UE, and signaling the configurable parameter to the at least one UE. In certain embodiments, the network node may take the parameter into account in scheduling and link adaptation decisions, and the parameter may be used in the PDSCH transmission. In an embodiment, the value of the parameter provides the power offset for the at least one UE to assume in CSI reporting for a UE supporting higher order modulation and/or for PDSCH decoding of a PDSCH carrying higher order modulation.

Another embodiment includes a method of power back-off aware CSI reporting. The method may include receiving, by a UE, an additional configurable parameter from the network. The method may further include using the additional configurable parameter for CSI estimation. In an embodiment, the value of the parameter provides the power offset for the UE, for example, to assume in CSI reporting.

Another embodiment includes a method of PDSCH decoding. The method may include receiving, by a UE, an additional configurable parameter from the network. The method may then include using the additional configurable parameter for decoding of PDSCH. In an embodiment, the value of the parameter provides the power offset for the UE, for example, to assume in CSI reporting.

Another embodiment is directed to a method including estimating an amount of the interference the UE observes that is due to EVM originated by transmissions from the eNB or eNBs transmitting the reference signals used to measure the CSI. The method may also include taking into account the estimated amount of interference due to EVM originated by transmissions from the eNB or eNBs transmitting the reference signals used to measure the CSI when computing the CSI report.

Another embodiment is directed to an apparatus including at least one processor, and at least one memory comprising computer program code. The at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus at least to define an additional configurable parameter that may be configured jointly with 256QAM DL operation, to configure the parameter for at least one UE, and to signal the parameter to the at least one UE. In some embodiments, the configurable parameter and 256QAM DL operation can be configured separately. In an embodiment, the value of the additional higher layer configurable parameter provides the power offset for the at least one UE, for example, to assume in CSI reporting and/or for PDSCH decoding of C S based transmissions.

Another embodiment is directed to an apparatus including at least one processor, and at least one memory comprising computer program code. The at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus at least to receive an additional configurable parameter from the network, and to use the additional higher layer configurable parameter for CSI estimation. In an embodiment, the value of the parameter provides the power offset for the UE, for example, to assume in CSI reporting.

Another embodiment is directed to an apparatus including at least one processor, and at least one memory comprising computer program code. The at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus at least to receive an additional configurable parameter from the network, and to use the additional configurable parameter for decoding of PDSCH.

Another embodiment is directed to an apparatus including at least one processor, and at least one memory comprising computer program code. The at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus at least to estimate an amount of the interference the UE observes that is due to EVM, and to take the estimated amount of interference due to EVM into account when computing the CSI report.

One having ordinary skill in the art will readily understand that the invention as discussed above may be practiced with steps in a different order, and/or with hardware elements in configurations which are different than those which are disclosed. Therefore, although the invention has been described based upon these preferred embodiments, it would be apparent to those of skill in the art that certain modifications, variations, and alternative constructions would be apparent, while remaining within the spirit and scope of the invention. In order to determine the metes and bounds of the invention, therefore, reference should be made to the appended claims.

Claims

We Claim:

1. An apparatus, comprising:

at least one processor; and

at least one memory including computer program code,

the at least one memory and computer program code configured, with the at least one processor, to cause the apparatus at least to

define an additional higher layer configurable parameter that is configured jointly with 256 quadrature amplitude modulation (256QAM) downlink (DL) operation, and

send the additional higher layer configurable parameter to at least one user equipment.

2. The apparatus according to claim 1, wherein a value of the additional higher layer configurable parameter provides a power offset for the user equipment to assume in channel state information (CSI) reporting or for physical downlink shared channel (PDSCH) decoding of at least one of cell-specific reference signals (C S) based transmissions or demodulation reference signals (DM-RS) based transmissions.

3. The apparatus according to claims 1 or 2, wherein the additional higher layer configurable parameter comprises P_256QAM_offset.

4. The apparatus according to any one of claims 1-3, wherein the at least one memory and computer program code are configured, with the at least one processor, to cause the apparatus at least to receive a channel quality indicator (CQI) report from the user equipment, wherein the received CQI report takes into account the power offset indicated by the value of the additional higher layer configurable parameter.

5. The apparatus according to any one of claims 1-4, wherein the at least one memory and computer program code are configured, with the at least one processor, to cause the apparatus at least to perform scheduling and link/rank/precoder adaptation taking into account the power offset.

6. The apparatus according to any one of claims 1-5, wherein the at least one memory and computer program code are configured, with the at least one processor, to cause the apparatus at least to use the power offset when transmitting the physical downlink shared channel (PDSCH) to the user equipment using 256QAM.

7. The apparatus according to any one of claims 1-6, wherein the apparatus comprises an evolved node B (eNB).

8. An apparatus, comprising:

means for defining an additional higher layer configurable parameter that is configured jointly with 256 quadrature amplitude modulation (256QAM) downlink (DL) operation; and

means for sending the additional higher layer configurable parameter to at least one user equipment.

9. A method, comprising:

defining, by a network node, an additional higher layer configurable parameter that is configured jointly with 256 quadrature amplitude modulation (256QAM) downlink (DL) operation; and

sending the additional higher layer configurable parameter to at least one user equipment.

10. The method according to claim 9, wherein a value of the additional higher layer configurable parameter provides a power offset for the user equipment to assume in channel state information (CSI) reporting or for physical downlink shared channel (PDSCH) decoding of at least one of cell-specific reference signals (CRS) based transmissions or demodulation reference signals (DM-RS) based transmissions.

1 1. The method according to claims 9 or 10, wherein the additional higher layer configurable parameter comprises P_256QAM_offset.

12. The method according to any one of claims 9-1 1, further comprising receiving a channel quality indicator (CQI) report from the user equipment, wherein the received CQI report takes into account the power offset indicated by the value of the additional higher layer configurable parameter.

13. The method according to any one of claims 9-12, further comprising performing scheduling and link/rank/precoder adaptation taking into account the power offset.

14. The method according to any one of claims 9-13, further comprising using the power offset when transmitting the physical downlink shared channel (PDSCH) to the user equipment using 256QAM.

15. An apparatus, comprising:

at least one processor; and

at least one memory including computer program code,

receive an additional higher layer configurable parameter that is configured jointly with 256 quadrature amplitude modulation (256QAM) downlink (DL) operation, and

use a value of the additional higher layer configurable parameter as a power offset to assume in channel state information (CSI) reporting or for physical downlink shared channel (PDSCH) decoding of at least one of cell-specific reference signals (C S) based transmissions or demodulation reference signals (DM-RS) based transmissions.

16. The apparatus according to claim 15, wherein the additional higher layer configurable parameter comprises P_256QAM_offset.

17. The apparatus according to any one of claims 15 or 16, wherein the at least one memory and computer program code are configured, with the at least one processor, to cause the apparatus at least to send a channel quality indicator (CQI) report to a network element, wherein the CQI report takes into account the power offset indicated by the value of the additional higher layer configurable parameter.

18. The apparatus according to any one of claims 15-17, wherein the apparatus comprises a user equipment.

19. An apparatus, comprising:

means for receiving, by a user equipment, an additional higher layer configurable parameter that is configured jointly with 256 quadrature amplitude modulation (256QAM) downlink (DL) operation; and

means for using a value of the additional higher layer configurable parameter as a power offset to assume in channel state information (CSI) reporting or for physical downlink shared channel (PDSCH) decoding of at least one of cell-specific reference signals (C S) based transmissions or demodulation reference signals (DM-RS) based transmissions.

20. A method, comprising:

receiving, by a user equipment, an additional higher layer configurable parameter that is configured jointly with 256 quadrature amplitude modulation (256QAM) downlink (DL) operation; and

using a value of the additional higher layer configurable parameter as a power offset to assume in channel state information (CSI) reporting or for physical downlink shared channel (PDSCH) decoding of at least one of cell-specific reference signals (CRS) based transmissions or demodulation reference signals (DM-RS) based transmissions.

21. The method according to claim 20, wherein the additional higher layer configurable parameter comprises P_256QAM_offset.

22. The method according to any one of claims 20 or 21, further comprising sending a channel quality indicator (CQI) report to a network element, wherein the CQI report takes into account the power offset indicated by the value of the additional higher layer configurable parameter.

23. A computer program, embodied on a computer readable medium, the computer program configured to control a processor to perform a method according to any one of claims 9-14 or 20-22.