Methods, apparatus, and computer programs for compensating phase noise

Abstract

Common phase error and / or inter-carrier interference. A technique comprising: transmitting data and / or control information; and transmitting a common phase error and / or inter-carrier interference correction reference signal, wherein the common phase error and / or inter-carrier interference correction reference signal occupies variable radio resources.

Description

[0001] This application is a divisional application of patent application no. 201680084006.9, filed on March 23, 2016, with the title "Common phase error and / or inter carrier interference".

[0002] Phase noise originating from an oscillator of a transmitting device can cause common phase error and inter carrier interference in an Orthogonal Frequency Division Multiplexing (OFDM) communication system. Such phase noise increases approximately quadratically with carrier frequency, and is therefore a particular problem for future wireless radio transmission technologies, in particular one for which high centimeter wavelength carrier frequencies and millimeter wavelength carrier frequencies (around 3400 MHz and higher) have been proposed, which are higher than currently used cellular carrier frequencies.

[0003] One conventional technique is to use an oscillator that produces less phase noise, but such an oscillator can increase the cost of producing a transmitting device, such as a user equipment (UE), which can or can not have a user interface, and includes, for example, high complexity devices such as smart phones and the like, low complexity devices such as machine type communication (MTC) devices, and other types of devices. Another conventional technique for reducing the phase noise of a given oscillator involves increasing the OFDM subcarrier spacing and reducing the OFDM symbol time period. A problem with this approach is that the increased CP overhead results in reduced spectral efficiency and achievable peak data rates. On the other hand, shortening the absolute length of the CP can result in severe performance degradation due to the delay spread of the radio channel, particularly when using multi-user multiple-input multiple-output (MU-MIMO) techniques. The use of massive MIMO planned for 5G brings even more challenges, and conventional approaches that can work with limited MU-MIMO scenarios can not work with massive MIMO deployments.

[0004] The inventors of the present application have identified a need for different techniques for handling phase noise in OFDM systems.

[0005] Accordingly, there is provided a method comprising receiving a radio transmission comprising data and / or control information, and a common phase error and / or inter carrier interference correction reference signal, wherein the common phase error and / or inter carrier interference correction reference signal occupies a variable amount of radio resources.

[0006] According to one embodiment, the common phase error and / or inter carrier interference correction reference signal is an in-band signal transmitted within a data and / or control channel for data and / or control information.

[0007] According to one embodiment, the radio resources used for the common phase error and / or inter-carrier interference correction reference signal are selected from at least two quantities: (i) zero radio resources and (ii) one or more radio resources.

[0008] According to one embodiment, the allocation of radio resources for a common phase error and / or inter-carrier interference correction reference signal is performed in one of two ways: (i) the resources are non-adjacent in frequency, and (ii) the resources are adjacent in frequency.

[0009] According to one embodiment, the variability and / or contiguousness of the radio resources occupied by the reference signal corrected by common phase error and / or intercarrier interference depends on at least one of the following: at least one nature of the data and / or control channel used for data and / or control information; the type of communication equipment for receiving and / or transmitting data and / or control information; the carrier frequency; and the subcarrier spacing.

[0010] According to one embodiment, the method further includes: determining from downlink control information the structure of a common phase error and / or inter-carrier interference correction reference signal from a set of possible structures that will be used for downlink data transmission.

[0011] According to one embodiment, the method further includes: determining from downlink control information the structure of a common phase error and / or inter-carrier interference correction reference signal from a set of possible structures that will be used for uplink data transmission.

[0012] According to one embodiment, the method further includes: using a received common phase error and / or inter-carrier interference correction reference signal to perform common phase error correction and / or inter-carrier interference cancellation.

[0013] According to one embodiment, the reception is performed at a user equipment or network infrastructure node.

[0014] According to one embodiment, the common phase error and / or inter-carrier interference correction reference signal occupies one or more subcarriers during the entire symbol time period allocated to the physical shared channel.

[0015] According to one embodiment, the common phase error and / or inter-carrier interference correction reference signal is included only when the transmission of the data and / or control information uses a modulation and / or coding scheme with a complexity order higher than a predetermined threshold.

[0016] According to one embodiment, the common phase error and / or inter-carrier interference correction reference signal occupies a predetermined portion of the radio resources allocated to the transmission of the data and / or control information.

[0017] According to one embodiment, the common phase error and / or inter-carrier interference correction reference signal occupies one or more subcarriers at predetermined positions within the entire subcarrier allocated for the transmission of the data and / or control information.

[0018] Accordingly, a method is also provided, comprising: transmitting data and / or control information; and transmitting a common phase error and / or inter-carrier interference correction reference signal, wherein the common phase error and / or inter-carrier interference correction reference signal occupies variable radio resources.

[0019] According to one embodiment, the common phase error and / or inter-carrier interference correction reference signal is an in-band signal transmitted within the data and / or control channel used for the data and / or control information.

[0020] According to one embodiment, the radio resources used for the common phase error and / or inter-carrier interference correction reference signal are selected from at least two quantities: (i) zero radio resources and (ii) one or more radio resources.

[0021] According to one embodiment, the allocation of radio resources for a common phase error and / or inter-carrier interference correction reference signal is performed in one of two ways: (i) the resources are non-adjacent in frequency, and (ii) the resources are adjacent in frequency.

[0022] According to one embodiment, the variability and / or contiguousness of the radio resources occupied by the reference signal corrected by common phase error and / or intercarrier interference depends on at least one of the following: at least one nature of the data and / or control channel used for data and / or control information; the type of communication equipment for receiving and / or transmitting data and / or control information; the subcarrier frequency; and the subcarrier spacing.

[0023] According to one embodiment, a common phase error and / or inter-carrier interference correction reference signal is transmitted so that the receiver can perform common phase error correction and / or inter-carrier interference cancellation.

[0024] According to one embodiment, the transmission takes place at a user equipment or network infrastructure node.

[0025] According to one embodiment, the method includes transmitting the common phase error and / or inter-carrier interference correction reference signal via one or more subcarriers over the entire symbol time period allocated to the transmission of the data and / or control information.

[0026] According to one embodiment, the method includes transmitting the common phase error and / or inter-carrier interference correction reference signal, as well as data and / or control information for physically sharing a channel, from one or more identical antenna ports.

[0027] According to one embodiment, the data and / or control information occupies radio resources shared by multiple communication devices according to spatial multiplexing technology, and the method includes: transmitting a common phase error and / or inter-carrier interference correction reference signal for one of the communication devices via radio resources orthogonal to radio resources used by other communication devices for the common phase error and / or inter-carrier interference correction reference signal.

[0028] According to one embodiment, the data and / or control information occupies radio resources shared by multiple communication devices according to spatial multiplexing technology, and the method includes: transmitting the common phase error and / or inter-carrier interference correction reference signal for the multiple communication devices via the same radio resources.

[0029] According to one embodiment, the data and / or control information occupies radio resources shared by multiple communication devices according to spatial multiplexing technology, and the method includes: transmitting a common phase error and / or inter-carrier interference correction reference signal for a communication device via a subcarrier that is not used by other communication devices in the communication device for the common phase error and / or inter-carrier interference correction reference signal.

[0030] According to one embodiment, the method includes transmitting the common phase error and / or inter-carrier interference correction reference signal only when the data and / or control information is transmitted using modulation with a complexity order higher than a predetermined threshold.

[0031] According to one embodiment, the method includes transmitting the common phase error and / or inter-carrier interference correction reference signal only when the data and / or control information is transmitted according to a modulation and coding scheme having a complexity order higher than a predetermined threshold.

[0032] According to one embodiment, the method includes transmitting the common phase error and / or inter-carrier interference correction reference signal within a predetermined portion of radio resources allocated to the data and / or control information.

[0033] According to one embodiment, the method includes transmitting the common phase error and / or inter-carrier interference correction reference signal via one or more subcarriers at predetermined positions within the entire subcarriers allocated for the transmission of the data and / or control information.

[0034] According to one embodiment, the amount and / or presence of radio resources for the common phase error and / or inter-carrier interference correction reference signal depends on the modulation and / or coding scheme.

[0035] According to one embodiment, the amount and / or presence of radio resources for the common phase error and / or inter-carrier interference correction reference signal depends on the receiver's ability to perform inter-carrier interference correction.

[0036] According to one embodiment, the method includes: transmitting information with a signal, the information indicating the structure of the common phase error and / or inter-carrier interference correction reference signal.

[0037] According to one embodiment, the amount of radio resources for the common phase error and / or inter-carrier interference correction reference signal is selected from the following three amounts: (i) no radio resources for the common phase error and / or inter-carrier interference correction reference signal; (ii) a first number of subcarriers for the common phase error and / or inter-carrier interference correction reference signal, so as to enable only CPE correction; and (iii) a second higher number of subcarriers for the common phase error and / or inter-carrier interference correction reference signal, so as to enable both CPE correction and ICI correction.

[0038] According to one embodiment, the common phase error and / or inter-carrier interference correction reference signal exists only in the data channel.

[0039] Accordingly, an apparatus is also provided, comprising: a processor and a memory including computer program code, wherein the memory and the computer program code are configured, together with the processor, such that the apparatus: receives radio transmissions including data and / or control information, and a common phase error and / or inter-carrier interference correction reference signal, wherein the common phase error and / or inter-carrier interference correction reference signal occupies variable radio resources.

[0040] According to one embodiment, the common phase error and / or inter-carrier interference correction reference signal is an in-band signal transmitted within a data and / or control channel used for data and / or control information.

[0041] According to one embodiment, the radio resources used for the common phase error and / or inter-carrier interference correction reference signal are selected from at least two quantities: (i) zero radio resources and (ii) one or more radio resources.

[0042] According to one embodiment, the allocation of radio resources for a common phase error and / or inter-carrier interference correction reference signal is performed in one of two ways: (i) the resources are non-adjacent in frequency, and (ii) the resources are adjacent in frequency.

[0043] According to one embodiment, the variability and / or contiguousness of the radio resources occupied by the reference signal corrected by common phase error and / or intercarrier interference depends on at least one of the following: at least one nature of the data and / or control channel used for data and / or control information; the type of communication equipment for receiving and / or transmitting data and / or control information; the carrier frequency; and the subcarrier spacing.

[0044] According to one embodiment, the memory and computer program code are further configured, together with the processor, to enable the device to: determine from the downlink control information the structure of a common phase error and / or inter-carrier interference correction reference signal from a set of possible structures that will be used for downlink data transmission.

[0045] According to one embodiment, the memory and computer program code are further configured, together with the processor, to enable the device to: determine from downlink control information the structure of a common phase error and / or inter-carrier interference correction reference signal from a set of possible structures that will be used for uplink data transmission.

[0046] According to one embodiment, the memory and computer program code are further configured, together with the processor, to enable the device to perform common phase error correction and / or inter-carrier interference cancellation using the received common phase error and / or inter-carrier interference correction reference signal.

[0047] According to one embodiment, the common phase error and / or inter-carrier interference correction reference signal occupies one or more subcarriers during the entire symbol time period allocated to the physical shared channel.

[0048] According to one embodiment, the common phase error and / or inter-carrier interference correction reference signal is included only when the transmission of the data and / or control information uses a modulation and / or coding scheme with a complexity order higher than a predetermined threshold.

[0049] According to one embodiment, the common phase error and / or inter-carrier interference correction reference signal occupies a predetermined portion of the radio resources allocated to the transmission of the data and / or control information.

[0050] According to one embodiment, the common phase error and / or inter-carrier interference correction reference signal occupies one or more subcarriers at predetermined positions within the entire subcarrier allocated for the transmission of the data and / or control information.

[0051] Accordingly, a user equipment or network infrastructure node including the apparatus described above is also provided.

[0052] Accordingly, an apparatus is also provided, comprising: a processor and a memory including computer program code, wherein the memory and the computer program code are configured, together with the processor, such that the apparatus: transmits data and / or control information; and transmits a common phase error and / or inter-carrier interference correction reference signal, wherein the common phase error and / or inter-carrier interference correction reference signal occupies variable radio resources.

[0053] According to one embodiment, the common phase error and / or inter-carrier interference correction reference signal is an in-band signal transmitted within the data and / or control channel used for the data and / or control information.

[0054] According to one embodiment, the radio resources used for the common phase error and / or inter-carrier interference correction reference signal are selected from at least two quantities: (i) zero radio resources and (ii) one or more radio resources.

[0055] According to one embodiment, the allocation of radio resources for a common phase error and / or inter-carrier interference correction reference signal is performed in one of two ways: (i) the resources are non-adjacent in frequency, and (ii) the resources are adjacent in frequency.

[0056] According to one embodiment, the variability and / or contiguousness of the radio resources occupied by the reference signal corrected by common phase error and / or intercarrier interference depends on at least one of the following: at least one nature of the data and / or control channel used for data and / or control information; the type of communication equipment for receiving and / or transmitting data and / or control information; the subcarrier frequency; and the subcarrier spacing.

[0057] According to one embodiment, a common phase error and / or inter-carrier interference correction reference signal is transmitted so that the receiver can perform common phase error correction and / or inter-carrier interference cancellation.

[0058] According to one embodiment, the memory and computer program code are further configured, together with the processor, to cause the device to transmit the common phase error and / or inter-carrier interference correction reference signal via one or more subcarriers over the entire symbol time period allocated to the transmission of the data and / or control information.

[0059] According to one embodiment, the memory and computer program code are further configured, together with the processor, to enable the device to transmit the common phase error and / or inter-carrier interference correction reference signal and data and / or control information for a physical shared channel from the same one or more antenna ports.

[0060] According to one embodiment, the data and / or control information occupies radio resources shared by multiple communication devices according to spatial multiplexing technology, and the memory and computer program code are further configured, together with the processor, such that the device: transmits the common phase error and / or inter-carrier interference correction reference signal for one of the communication devices via radio resources orthogonal to the radio resources used by the other communication devices for the common phase error and / or inter-carrier interference correction reference signal.

[0061] According to one embodiment, the data and / or control information occupies radio resources shared by multiple communication devices according to spatial multiplexing technology, and the memory and computer program code are further configured, together with the processor, such that the device: transmits the common phase error and / or inter-carrier interference correction reference signal for the multiple communication devices via the same radio resources.

[0062] According to one embodiment, the data and / or control information occupies radio resources shared by multiple communication devices according to spatial multiplexing technology, and the memory and computer program code are further configured, together with the processor, such that the device: transmits a common phase error and / or inter-carrier interference correction reference signal for a communication device via a subcarrier that is not used by other communication devices in the communication device for the common phase error and / or inter-carrier interference correction reference signal.

[0063] According to one embodiment, the memory and computer program code are further configured, together with the processor, such that the device transmits the common phase error and / or inter-carrier interference correction reference signal only when the data and / or control information is transmitted using modulation with a complexity order higher than a predetermined threshold.

[0064] According to one embodiment, the memory and computer program code are further configured, together with the processor, such that the device transmits the common phase error and / or inter-carrier interference correction reference signal only when the data and / or control information is transmitted according to a modulation and coding scheme having a complexity order higher than a predetermined threshold.

[0065] According to one embodiment, the memory and computer program code are further configured, together with the processor, to cause the device to transmit the common phase error and / or inter-carrier interference correction reference signal within a predetermined portion of the radio resources allocated to the data and / or control information.

[0066] According to one embodiment, the memory and computer program code are further configured, together with the processor, to cause the device to transmit the common phase error and / or inter-carrier interference correction reference signal via one or more subcarriers at predetermined positions within the entire subcarriers allocated for the transmission of the data and / or control information.

[0067] According to one embodiment, the amount and / or presence of radio resources for the common phase error and / or inter-carrier interference correction reference signal depends on the modulation and / or coding scheme.

[0068] According to one embodiment, the amount and / or presence of radio resources for the common phase error and / or inter-carrier interference correction reference signal depends on the receiver's ability to perform inter-carrier interference correction.

[0069] According to one embodiment, the memory and computer program code are further configured, together with the processor, to cause the device to: transmit information by signaling, the information indicating the structure of the common phase error and / or inter-carrier interference correction reference signal.

[0070] According to one embodiment, the amount of radio resources for the common phase error and / or inter-carrier interference correction reference signal is selected from the following three amounts: (i) no radio resources for the common phase error and / or inter-carrier interference correction reference signal; (ii) a first number of subcarriers for the common phase error and / or inter-carrier interference correction reference signal, so as to enable only CPE correction; and (iii) a second higher number of subcarriers for the common phase error and / or inter-carrier interference correction reference signal, so as to enable both CPE correction and ICI correction.

[0071] According to one embodiment, the common phase error and / or inter-carrier interference correction reference signal exists only in the data channel.

[0072] Accordingly, a user equipment or network infrastructure node including the above-described device is also provided.

[0073] Accordingly, a computer program product including program code components is also provided, which, when loaded into a computer, control the computer to: receive radio transmissions including data and / or control information, and common phase error and / or inter-carrier interference correction reference signals, wherein the common phase error and / or inter-carrier interference correction reference signals occupy variable radio resources.

[0074] Accordingly, a computer program product including program code components is also provided, which, when loaded into a computer, control the computer to: transmit data and / or control information; and transmit a common phase error and / or inter-carrier interference correction reference signal, wherein the common phase error and / or inter-carrier interference correction reference signal occupies variable radio resources.

[0075] Phase noise consists of common phase error (CPE) and random phase error. Random phase error causes inter-carrier interference (ICI).

[0076] Some embodiments of the present invention involve CPE and / or ICI compensation.

[0077] One technique for addressing phase noise compensation involves continuously transmitting additional reference signals from all antenna ports, within the same OFDM symbol time period in each subframe, via a continuous set of OFDM subcarriers at predetermined locations for the total carrier bandwidth of the cell. These additional reference signals facilitate compensation for phase noise (CPE and / or CPI) at the receiver; and using this same set of reference signals at the receiver to facilitate compensation for phase noise across the entire set of carriers used for radio transmission. This technique can be viewed as a single-antenna-port transmission scheme, and the frequency division multiplexing (FDM) transmission to multiple UEs can lead to distributed resource allocation within the antenna ports, which can cause problems with large carrier bandwidths and hybrid architectures that typically use distributed power amplifier architectures. Due to the large carrier bandwidth, it may be impossible to use digital predistortion to reduce intermodulation distortion, which would then require a transmission power reduction of up to approximately 10 dB at the transmitter, potentially leading to a drastic reduction in the transmitter's geographic coverage. Another approach could be to introduce several pilot subcarriers for each OFDMA symbol to facilitate CPE correction. However, the problem with this approach is that this structure cannot achieve high performance at high SNR because ICI compensation is not possible.

[0078] Therefore, it is preferable to introduce an adaptive reference signal structure that can handle both ICI and CPE compensation depending on actual needs, without incurring excessive overhead on the system.

[0079] The need for CPE and / or ICI compensation may depend on the SNR. For example, in high SNR environments, providing both ICI and CPE compensation can significantly improve performance. In medium SNR environments, ICI compensation may not be necessary, as it may introduce performance loss due to sensitivity to noise. In low SNR environments, neither CPE nor ICI compensation may be necessary, as performance is limited by thermal noise / interference.

[0080] Some embodiments relate to an adaptive reference signal (RS) structure (CPE / ICI-RS) that can address CPE and / or ICI correction. The presence and / or structure of the adaptive reference signal can depend on the modulation and coding scheme (MCS) used by the transmitted data. For example, with a higher MCS, the CPE / ICI-RS can occupy more subcarriers, and with a lower MCS, the CPE / ICI-RS can occupy fewer subcarriers. In some embodiments, with a very low MCS, the CPE / ICI-RS may not exist at all. The amount of subcarriers occupied by the CPE / ICI-RS can depend on whether both CPE and ICI correction are required, or whether only CPE correction is required.

[0081] In a non-limiting example, the CPE / ICI-RS may exist only in the data channel. This could be done, for example, if the MCS of the control section is not very high. In this case, ICI compensation may not be necessary. Furthermore, since the control channel OFDMA symbols contain a dedicated reference signal carrier, CPE compensation can be performed (if needed) through the normal channel estimation process.

[0082] In an example embodiment, the CPE / ICI-RS may exist at a predetermined location in the data portion of a subframe. The presence of the CPE / ICI-RS may depend on the MCS scheme. For example, in the case of higher-order modulation (e.g., 64QAM and higher), the CPE / ICI-RS may exist, and in the case of lower-order modulation, the CPE / ICI-RS may not exist. In some embodiments, the CPE / ICI-RS occupies a varying number of subcarriers, for example, as follows:

[0083] If the MCS is low (e.g., QPSK), no CPE / ICI correction is needed, so the RS occupies 0 subcarriers (it does not exist); if the MCS is medium (e.g., 16QAM), only CPE correction is needed, so the RS can occupy only one or a few subcarriers within the xPDSCH / xPUSCH; if the MCS is high (e.g., 64QAM or higher), both CPE and ICE corrections are needed, and the CPE / ICI corrected RS will occupy more subcarriers within the xPDSCH / xPUSCH (ICI compensation requires significantly more subcarriers than CPE compensation).

[0084] In some embodiments, the amount of resources used for the CPE / ICI reference signal, which is added to or replaces the scheme described above, may depend on the receiver's ability to perform ICI correction.

[0085] Examples of techniques according to embodiments of the present invention will be described in detail below by way of example only, with reference to the accompanying drawings, in which:

[0086] Figure 1 The illustration shows an example of an environment in which embodiments of the present invention may be implemented;

[0087] Figure 2 The diagram illustrates the use of in Figure 1 An example of a device used at the UE;

[0088] Figure 3 The diagram illustrates the use of in Figure 1 An example of a device used at an eNB;

[0089] Figure 4 The illustration shows an example of configuring CPE / ICI-RS for an uplink OFDM radio resource set allocated to four spatially multiplexed UEs;

[0090] Figure 5 The illustration shows an example of configuring CPE / ICI-RS for a set of downlink OFDM radio resources allocated to four spatially multiplexed UEs;

[0091] Figure 6 The illustration shows another example of configuring CPE / ICI-RS for a set of downlink OFDM radio resources allocated to four spatially multiplexed UEs;

[0092] Figure 7 The illustration shows an example of an uplink operation set at the eNB and UE according to an embodiment of the present invention;

[0093] Figure 8 The illustration shows another example of the downlink operation set at the UE and eNB according to another embodiment of the present invention; and

[0094] Figure 9 The illustration shows an embodiment of the invention. Figure 1 An example of operation at the transmitting device (UE or eNB).

[0095] The following describes in detail the technology according to an embodiment of the invention with reference to an example of a communication system, which is based on dividing radio resources into blocks of 14 OFDM symbol time periods, but the same technology is applicable to other communication systems.

[0096] Figure 1 An example of four user equipment (UEs) (e.g., high-complexity devices such as smartphones, low-complexity devices such as MTC devices, or any other type of wireless communication device) 8 located within the coverage area of ​​a cell operated by wireless network infrastructure nodes (wireless access points, eNBs, and the like) 2 belonging to a radio access network. Figure 1The illustration shows an example of an eNB as a cell node; however, it should be understood that any other type of wireless infrastructure node can exist in place of an eNB. Furthermore, Figure 1 Only a small number of eNBs are shown, but radio access networks typically include a large number of eNBs, each operating one or more cells.

[0097] Each eNB 2 in a radio access network is typically connected to one or more core network entities and / or mobility management entities, but for simplicity, these other entities are... Figure 1 omitted.

[0098] Figure 2 A schematic view of an example apparatus for each UE 8 is shown. The UE 8 can be used for a variety of tasks, such as making and receiving telephone calls, receiving and sending data to and from a data network, and experiencing multimedia or other content. The UE 8 can be any device that is at least capable of both recovering data / information from radio transmissions carried out by the eNB 2 and performing radio transmissions from which data / information can be recovered by the eNB 2. Non-limiting examples of the user equipment (UE) 8 include smartphones, tablets, personal computers, and devices without any user interface, such as devices designed for machine-type communications (MTC).

[0099] refer to Figure 2 The baseband processor 34, operating according to program code stored in memory 32, controls the generation and transmission of radio signals via a radio frequency (RF) front-end 36 and an antenna 38. The RF front-end 36 may include an analog transceiver, filters, a duplexer, and an antenna switch. Furthermore, the combination of the antenna 38, the RF front-end 36, and the baseband processor 34 recovers data / information from radio signals arriving at UE 8 from, for example, eNB 2. UE 8 may also include an application processor (not shown) that generates user data for transmission via radio signals and processes the user data recovered from the radio signals by the baseband processor 34 and stored in memory 32.

[0100] The application processor and baseband processor 34 can be implemented as separate chips or combined into a single chip. The memory 32 can be implemented as one or more chips. The memory 32 may include both read-only memory and random access memory. These components can be provided on one or more circuit boards.

[0101] UE may include Figure 2Other components not shown. For example, UE 8 may include a user interface, such as a keypad, a voice command recognition device, a touchscreen or touchpad, a combination thereof, or the like, through which a user can control the operation of UE 8. UE 8 may also include a display, speakers, and a microphone. In addition, UE 8 may include appropriate connectors (wired or wireless) for connecting to other devices and / or for connecting external accessories (e.g., hands-free devices).

[0102] Figure 3 It shows the use of in Figure 1 An example of a device used at eNB 2. A broadband processor 20, operating according to program code stored in memory 22, (a) controls the generation and transmission of radio signals via a combination of RF front-end 24 and antenna 26; and (b) recovers data from radio signals arriving at the eNB from, for example, UE 8. The RF front-end may include an analog transceiver, filters, a duplexer, and an antenna switch. Both processor 20 and memory 22 may be implemented as one or more chips. Memory 22 may include both read-only memory and random access memory. The aforementioned components may be provided on one or more circuit boards. The device also includes an interface 28 for transmitting data to and from one or more other entities, such as, for example, a core network entity, a mobility management entity, and other eNBs in the same access network.

[0103] It should be understood that the above description Figure 2 and Figure 3 The apparatus shown in each of the accompanying drawings may include additional elements not directly related to embodiments of the invention described below.

[0104] Figure 7 An example of uplink operation at UE 8 and eNB 2 according to one embodiment is illustrated. All operations performed by UE processor 34 follow program code stored in UE memory 32; and all operations performed by eNB processor 20 follow program code stored in eNB memory 22.

[0105] For further reference Figure 4 The OFDM time-frequency resource set for a cell operated by eNB 2 is assigned to, for example, the uplink transmission of four spatially multiplexed UE 8s. The OFDM resource set is defined by a combination of: (i) in the frequency domain, a subset of, for example, 48 OFDM subcarriers (e.g., #0 to #47) within a larger number of total OFDM subcarriers for the cell; and (ii) in the time domain, a specific subframe comprising a 14-symbol time period (also simply referred to as OFDM symbols). Figure 4As shown, OFDM symbol #2 is used for the demodulation reference signal (DMRS), and OFDM symbols #3 through #13 are allocated to the physical uplink shared channel (e.g., using xPUSCH, a term adopted for fifth-generation (5G) systems). As mentioned above, Figure 4 The illustration shows a non-limiting example of how data signals and reference signals can be multiplexed, as well as a non-limiting example of radio resource structure.

[0106] Figure 4 The OFDM radio resource set is shared by the UE baseband processor 34 at each of the four spatially multiplexed (according to MU-MIMO technology) UE 8 locations. During OFDM symbol time periods #3 to #13 (via front-end 36 and antenna 38), xPUSCH radio transmissions are performed (from which eNB 2 can extract data and / or control information), and at predetermined locations within the entire subset of 48 OFDM subcarriers, via a corresponding OFDM subcarrier in a set of four consecutive OFDM subcarriers, the CPE / ICI-RS (Common Phase Error / Inter-Carrier Interference Reference Signal) is included within the same group of OFDM symbols #3 to #13. Figure 7 Step 702). As part of the process of extracting xPUSCH data from radio transmissions within OFDM symbols #3 to #13, the CPE / ICI-RS is used by the receiver (i.e., eNB2) to correct and compensate for common phase errors and / or inter-carrier interference. The xPUSCH data is rate-matched or punctured around the CPE / ICI-RS. The location of the set of four consecutive subcarriers for the CPE / ICI-RS is known to eNB2, and eNB2 can also derive information from the indicated DMRS index regarding how the set of four consecutive subcarriers is shared among the four spatially multiplexed UEs 8. Using mutually orthogonal resources for the CPE / ICI-RS for each of the four UEs (i.e., in this example, using a corresponding dedicated OFDM subcarrier for the CPE / ICI-RS for each of the four spatially multiplexed UEs) allows eNB2 to perform CPE / ICI correction independently for each of the four UEs 8, thereby supporting MU-MIMO for the uplink.

[0107] As discussed in more detail below, UE 8 may not always include CPE / ICI-RS in the resources allocated for xPUSCH used by that UE 8. For example, UE 8 may determine whether to include CPE / ICI-RS based on information about the modulation and coding scheme (MCS) used for xPUSCH transmissions in UL scheduling assignments; and even when the complexity order of the MCS indicates the use of CPE / ICI-RS, different CPE / ICI-RS patterns can be predefined for different complexity orders of the MCS.

[0108] Each of the four spatially multiplexed UE 8 units is assigned its own CPE / ICI-RS antenna port (AP). These are numbered as follows: Figure 4 Examples include 50, 51, 52, and 53.

[0109] The eNB baseband processor 20 (via eNB antenna 26 and eNB RF front end 24) extracts xPUSCH data for each of the four UE 8s from radio transmissions in OFDM symbols #3 to #13. As part of the extraction of xPUSCH data for the respective UE 8, the eNB baseband processor 20 uses the CPE / ICI-RS for each UE 8 to correct and / or compensate for common phase errors and / or inter-carrier interference. Figure 7 Step 704).

[0110] Figure 8 The illustration shows an example of downlink operation at eNB 2 and UE 8 according to one embodiment. All operations performed by UE processor 34 follow program code stored in UE memory 32; and all operations performed by eNB processor 20 follow program code stored in eNB memory 22.

[0111] For further reference Figure 5 The OFDM time-frequency resource set for cells operated by eNB 2 is collectively assigned to downlink transmissions to, for example, four spatially multiplexed UE 8. The OFDM resource set is defined by a combination of: (i) a subset of the total number of OFDM subcarriers for the cell in the frequency domain, and (ii) a specific subframe comprising 14 OFDM symbols in the time domain. Figure 5 As shown, OFDM symbol #2 is used for demodulation reference signal (DMRS), and OFDM symbols #3 to #13 are allocated to the physical downlink shared channel (e.g., using xPDSCH, a term adopted for fifth-generation (5G) systems).

[0112] The eNB baseband processor 20 performs radio transmissions on OFDM symbols #3 to #13 (via the eNB front end 24 and the eNB antenna 26). Figure 5 The UE 8, whose OFDM radio resource set is allocated to four spatially multiplexed (according to MU-MIMO technology), can extract xPDSCH data from it; and the eNB processor 24 includes CPE / ICI-RS (Common Phase Error / Inter-Carrier Interference Reference Signal) in the same group of OFDM symbols #3 to #13 at a predetermined position within the entire subset of OFDM subcarriers jointly allocated to the four UEs, for example, in the middle of the total number of subcarriers jointly allocated to the four UEs, via a set of consecutive OFDM subcarriers. Figure 8 Step 802). As part of the process of extracting xPDSCH data from radio transmissions within OFDM symbols #3 to #13, the CPE / ICI-RS is used by four UEs 8 to correct and compensate for common phase errors and / or inter-carrier interference. The xPDSCH data is rate-matched or punctured around the CPE / ICI-RS. The location of the set of OFDM subcarriers used for the CPE / ICI-RS is known to the UE 8.

[0113] CPE / ICI-RS signals can be used via all eNB antenna ports (APs) through which they are transmitted. Figure 5 In the downlink example, the same OFDM subcarrier resources are used because receiving UE 8 performs CPE and / or ICI corrections entirely from a common source. Therefore, a more compressed structure can be used for downlink CPE / ICI-RS assigned to multiple spatially multiplexed UEs' OFDM resource sets, compared to uplink CPE / ICI-RS assigned to multiple spatially multiplexed UEs' OFDM resource sets. Figure 5 In the example, the CPE / ICI-RS occupies a relatively large number of OFDM subcarriers (e.g., seven OFDM subcarriers) to enable both CPE correction and ICI correction for PDSCH radio transmissions based on relatively complex modulation and coding schemes. The CPE / ICI-RS occupies a subset of the total number of OFDM subcarriers shared among four spatially multiplexed UEs in a localized manner; and the CPE / ICI-RS is transmitted from the same antenna port used to transmit xPDSCH to the UEs. Including the CPE / ICI-RS within the radio resources allocated to xPDSCH avoids the problems associated with distributed resource allocation.

[0114] according to Figure 6Another example shown illustrates that the downlink CPE / ICI-RS occupies only one OFDM subcarrier (e.g., an intermediate subcarrier) from a subset of carriers that are collectively allocated to the downlink PDSCH of four spatially multiplexed UEs. This pattern can be suitable for xPDSCH transmissions with relatively low-complexity modulation and coding schemes, for which there is less need for inter-carrier cancellation, and the receiver (i.e., the UE) only needs to perform common phase error correction (without performing inter-carrier cancellation) as part of extracting xPDSCH data from the radio transmission. Depending on the allocated bandwidth, more CPE / ICI-RS can be distributed within the radio resources allocated to the xPDSCH for the UE.

[0115] At each of the four spatially multiplexed UEs to which the radio resource set is jointly allocated, the UE baseband processor 34 (via UE antenna 38 and UE RF front end 36) extracts xPDSCH data from the radio transmissions and, as part of the extracted xPDSCH data, uses CPE / ICI-RS to correct / compensate common phase errors and / or inter-carrier interference. Figure 8 Step 804).

[0116] As described above, different CPE / ICI-RS patterns can be used for both downlink and uplink transmissions. The CPE / ICI-RS pattern (or the selection of the CPE / ICI-RS pattern) can be optimized independently for each of the downlink and uplink.

[0117] As discussed in more detail below, eNB 2 may not always include CPE / ICI-RS in the resources that are collectively allocated to the xPDSCH of the four spatially multiplexed UEs. For example, eNB 2 may determine whether to include CPE / ICI-RS based on which modulation and coding scheme (MCS) will be used for xPDSCH transmission, and may determine which CPE / ICI-RS pattern to adopt based on the complexity order of the MCS used for xPDSCH transmission. UE 8 is notified which MCS will be used in DL scheduling assignment, and UE memory 32 stores predetermined rules relating to how different MCSs are mapped to different CPE / ICI-RS patterns; and UE baseband processor 34 can therefore also determine whether CPE / ICI-RS will be included, and if so, based on which CPE / ICI-RS pattern.

[0118] The embodiments described above are examples of spatially multiplexed UEs sharing the same time-frequency radio resources, but the technique is equally applicable to sets of OFDM time-frequency resources allocated to a single UE.

[0119] As mentioned above, this technique can involve rules relating to when to include CPE / ICI-RS and, if included, which CPE / ICI-RS pattern to use. For example, this technique can involve rules according to which CPE / ICI-RS is included only when the modulation used for xPDSCH / xPUSCH transmission has a complexity order higher than a predetermined threshold, for example, only when 64QAM or a higher modulation order is used. This technique can also involve rules according to which CPE / ICI-RS is included only when the MCS used for xPDSCH / xPUSCH transmission has a complexity order higher than a predetermined threshold. According to a specific example, the number of OFDM subcarriers used for CPE / ICI-RS within the xPDSCH / xPUSCH allocation depends on the MCS used for xPDSCH / xPUSCH transmission, according to the following rules: (a) no CPE / ICI-RS for QPSK (Quadrature Phase Shift Keying) modulation; (b) for 16QAM (Quadrature Amplitude Modulation), the CPE / ICI-RS on a relatively small predetermined number of subcarriers within the xPDSCH / xPUSCH allocation is sufficient to support common phase error correction; and (c) for 64QAM or higher modulation, the CPE / ICI-RS on a larger predetermined number of subcarriers within the xPDSCH / xPUSCH correction is sufficient to support both common phase error correction and inter-carrier interference cancellation.

[0120] Alternatively and / or additionally, a CPE / ICI-RS may be included only if the transmitting / receiving UE is one of one or more predefined UE categories. For example, a CPE / ICI-RS may be included only if the transmitting / receiving UE has a UE category that supports high MCS and / or has sufficient processing power.

[0121] Alternatively and / or additionally, CPE / ICI-RS may be included only when operating with a predetermined carrier frequency (e.g., a carrier frequency above a predetermined threshold), and / or only when operating with a predetermined subcarrier spacing (e.g., a subcarrier spacing below a predetermined threshold). With relatively low carrier frequencies and / or relatively large subcarrier spacing, CPE / ICI may have fewer problems.

[0122] Figure 9The illustration shows an example of an operational set for determining the amount of radio resources available for CPE / ICI-RS at the transmitting device (UE 8 or eNB 2). The baseband processor determines, based on one or more of the determination factors mentioned above, whether the radio transmission of data and / or control information will be accompanied by the transmission of CPE-ICI-RS (step 902). If the determination by the baseband processor is negative, the baseband processor transmits (via the RF front end and antenna) data and / or control information without any CPE-ICI-RS (step 904). On the other hand, if the determination in step 902 is positive, the baseband processor determines the amount of radio resources available for CPE / ICI-RS based on one or more of the determination factors mentioned above (step 906); and multiplexes the determined amount of CPE / ICI-RS with data and / or control information for transmission via the RF front end and antenna.

[0123] exist Figures 4 to 6 In the example shown in the diagram, the CPE / ICI-RS only occupies the OFDM symbols in the xPDSCH / xPUSCH portion of the radio resource set allocated to the spatially multiplexed UE (or a single UE). In other words, the CPE / ICI-RS may not occupy OFDM symbols allocated to the control channel, especially if the demodulated RS (DMRS) is multiplexed into the same OFDM symbols as the control channel symbols.

[0124] In the techniques described above, from the perspective of the transmitted data channel, the CPE / ICI-RS is an "in-band signal" (i.e., not transmitted outside the set of radio resources used for xPDSCH / xPUSCH transmissions, for which they will be used to correct common phase errors and / or eliminate inter-carrier interference). This ensures that xPDSCH / xPUSCH transmissions can always remain localized, even when multiplexed with the CPE / ICI-RS.

[0125] When loaded onto a computer, a suitably adapted computer program code product can be used to implement embodiments. The program code product for providing operation can be stored on a carrier medium, such as a carrier disk, card, or tape, and provided by means of that medium. One possibility is to download the program code product via a data network. Implementations can be provided using suitable software in a server.

[0126] Embodiments of the present invention can be practiced in various components, such as integrated circuit modules. The design of integrated circuits is essentially a highly automated process. Complex and powerful software tools can be used to transform logic-level designs into semiconductor circuit designs ready to be etched and formed on semiconductor substrates.

[0127] Programs, such as those offered by Synopsys in Mountain View, California, and Cadence Design in San Jose, California, automatically route conductors and position components on semiconductor chips using well-established design rules and libraries of pre-stored design modules. Once the design for the semiconductor circuit has been completed, the resulting design in a standardized electronic format (e.g., Opus, GDSII, or similar) can be transferred to a semiconductor manufacturing facility or "wafer fab" for fabrication.

[0128] In addition to the modifications explicitly mentioned above, it will be apparent to those skilled in the art that various other modifications can be made to the described embodiments within the scope of this invention.

Claims

1. A method for wireless communication, the method comprising: determining, based at least on information about a modulation and coding scheme to be used for a transmission of data or control information for a physical downlink shared channel, orthogonal frequency-division multiplexing (OFDM) symbols in the physical downlink shared channel for a transmission of one or more common phase error / carrier phase error (CPE / ICI) reference signals; mapping the one or more CPE / ICI reference signals to the OFDM symbols in the physical downlink shared channel, wherein the OFDM symbols to which the one or more CPE / ICI reference signals are mapped are different from other OFDM symbols used as demodulation reference signals for the physical downlink shared channel, wherein the one or more CPE / ICI reference signals are in-band signals within the physical downlink shared channel, wherein the physical downlink shared channel further comprises data, and wherein an amount of the OFDM symbols in the physical downlink shared channel depends at least on the information about the modulation and coding scheme used for the transmission of the data and the one or more CPE / ICI reference signals in the physical downlink shared channel; and transmitting, by a transmission device, the data and the one or more CPE / ICI reference signals for compensation of phase noise in the physical downlink shared channel via a radio communication using a same at least one antenna port of the transmission device.

2. The method of claim 1, wherein the OFDM symbols in the physical downlink shared channel are discontinuous in frequency.

3. The method of any one of claims 1-2, wherein the same at least one antenna port of the transmission device is a same single antenna port of the transmission device.

4. The method of any one of claims 1-2, wherein the same at least one antenna port of the transmission device comprises a same plurality of antenna ports of the transmission device.

5. The method of any one of claims 1-2, wherein the transmission device comprises or is comprised in a network infrastructure node.

6. The method of claim 5, wherein the transmitting comprises: transmitting, using the network infrastructure node, the radio communication comprising the one or more CPE / ICI reference signals and the data in the physical downlink shared channel to a user device.

7. A method for wireless communication, the method comprising: at the user equipment, receiving, from a transmission device, via a radio communication, data and one or more common phase error / carrier phase interference (CPE / ICI) reference signals for compensation of phase noise within a physical downlink shared channel for receiving the one or more CPE / ICI reference signals, wherein the one or more CPE / ICI reference signals are in-band signals within the physical downlink shared channel, wherein the radio communication comprising the one or more CPE / ICI reference signals and the data is transmitted by the transmission device using a same at least one antenna port of the transmission device, and wherein the one or more CPE / ICI reference signals are mapped to orthogonal frequency-division multiplexing (OFDM) symbols in the physical downlink shared channel, wherein the OFDM symbols to which the one or more CPE / ICI reference signals are mapped are different from other OFDM symbols used as demodulation reference signals for the physical downlink shared channel, wherein the one or more CPE / ICI reference signals are received after transmission of the one or more CPE / ICI reference signals from the same one or more antenna ports used to transmit the data and the one or more CPE / ICI reference signals; at the user equipment, receiving information about a modulation and coding scheme used for scheduling a downlink allocation of the data and the one or more CPE / ICI reference signals in the physical downlink shared channel, wherein an amount of the OFDM symbols in the physical downlink shared channel depends at least on the information about the modulation and coding scheme used for scheduling a downlink allocation of the data and the one or more CPE / ICI reference signals in the physical downlink shared channel; and at the user equipment, using the one or more CPE / ICI reference signals for compensation of phase noise.

8. The method of claim 7, wherein the OFDM symbols in the physical downlink shared channel are non-contiguous in frequency.

9. The method of any one of claims 7-8, wherein the same at least one antenna port of the transmission device is a same single antenna port of the transmission device.

10. The method of any one of claims 7-8, wherein the same at least one antenna port of the transmission device comprises a same plurality of antenna ports of the transmission device.

11. The method of any one of claims 7-8, wherein the transmission device comprises a network infrastructure node, or is comprised in the network infrastructure node. at the user equipment, receiving, from the network infrastructure node, via the radio communication, the one or more CPE / ICI reference signals and the data in the physical downlink shared channel.

12. The method of claim 11, wherein the receiving comprises:

13. An apparatus for wireless communication, the apparatus comprising: at least one processor; and ​ at least one memory including instructions stored thereon that, when executed by the at least one processor, cause the apparatus to at least perform: determining, based at least on information about a modulation and coding scheme to be used for transmission of data or control information for a physical downlink shared channel, orthogonal frequency-division multiplexing (OFDM) symbols in the physical downlink shared channel for transmission of one or more common phase error / carrier phase error (CPE / ICI) reference signals; mapping the one or more CPE / ICI reference signals to the OFDM symbols in the physical downlink shared channel, wherein the OFDM symbols to which the one or more CPE / ICI reference signals are mapped are different from other OFDM symbols used as demodulation reference signals for the physical downlink shared channel, wherein the one or more CPE / ICI reference signals are in-band signals within the physical downlink shared channel, wherein the physical downlink shared channel further comprises data, and wherein an amount of the OFDM symbols in the physical downlink shared channel depends at least on the information about the modulation and coding scheme used for the transmission of the data and the one or more CPE / ICI reference signals in the physical downlink shared channel; and transmitting, via a radio communication, the data and the one or more CPE / ICI reference signals for compensation of phase noise in the physical downlink shared channel to a user equipment using the same at least one antenna port of the apparatus.

14. The apparatus according to claim 13, wherein the OFDM symbols in the physical downlink shared channel are discontinuous in frequency.

15. The apparatus according to any one of claims 13-14, wherein the same at least one antenna port of the apparatus is a same single antenna port of the apparatus.

16. The apparatus according to any one of claims 13-14, wherein the same at least one antenna port of the apparatus comprises a same plurality of antenna ports of the apparatus.

17. The apparatus according to any one of claims 13-14, wherein the apparatus comprises or is comprised in a network infrastructure node.

18. The apparatus of claim 17, wherein the transmission comprises: transmitting, using the network infrastructure node, the radio communication comprising the one or more CPE / ICI reference signals and the data in the physical downlink shared channel to the user equipment.

19. An apparatus for wireless communication, the apparatus comprising: at least one processor; and at least one memory including instructions stored thereon that, when executed by the at least one processor, cause the apparatus to at least perform: receiving, from a transmission device, data and one or more common phase error / carrier phase interference (CPE / ICI) reference signals for compensation of phase noise in a physical downlink shared channel for receiving the one or more CPE / ICI reference signals via radio communication, wherein the radio communication comprising the one or more CPE / ICI reference signals and the data is transmitted by the transmission device using a same at least one antenna port of the transmission device, and wherein the one or more CPE / ICI reference signals are mapped to orthogonal frequency-division multiplexing (OFDM) symbols in the physical downlink shared channel, wherein the OFDM symbols to which the one or more CPE / ICI reference signals are mapped are different from other OFDM symbols used as demodulation reference signals for the physical downlink shared channel, wherein the one or more CPE / ICI reference signals are received after transmission of the one or more CPE / ICI reference signals from the same one or more antenna ports used to transmit the data and the one or more CPE / ICI reference signals; receiving information about a modulation and coding scheme used for scheduling a downlink allocation of the data and the one or more CPE / ICI reference signals in the physical downlink shared channel, wherein the amount of the OFDM symbols in the physical downlink shared channel depends at least on the information about the modulation and coding scheme used for scheduling a downlink allocation of the data and the one or more CPE / ICI reference signals in the physical downlink shared channel; and using the one or more CPE / ICI reference signals for compensating phase noise.

20. The apparatus according to claim 19, wherein the OFDM symbols in the physical downlink shared channel are discontinuous in frequency.

21. The apparatus according to any one of claims 19-20, wherein the same at least one antenna port of the transmission device is a same single antenna port of the transmission device.

22. The apparatus according to any one of claims 19-20, wherein the same at least one antenna port of the transmission device comprises a same plurality of antenna ports of the transmission device.

23. The apparatus according to any one of claims 19-20, wherein the transmission device comprises a network infrastructure node, or is comprised in the network infrastructure node. receiving, from the network infrastructure node, the radio communication comprising the one or more CPE / ICI reference signals and the data in the physical downlink shared channel.

24. The apparatus of claim 23, wherein the receiving comprises: means for performing the method according to any one of claims 1 to 6.

25. A network infrastructure node, comprising: means for performing the method according to any one of claims 7 to 12.

26. A user equipment comprising:

27. A network infrastructure node comprising the apparatus according to any one of claims 13 to 18. ​ 28. A user equipment comprising the apparatus of any one of claims 19-24.

29. A computer program product for wireless communication, the computer program product comprising a non-transitory computer-readable storage medium including instructions stored on the medium that, when executed by a processor of an apparatus, cause the apparatus to perform the method of any of claims 1-6 or any of claims 7-12.

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