Multiple-input and multiple-output demodulation of non-uniformly modulated constellations

Abstract

Some wireless communication systems modulate signals for transmission via a channel. Probability shaping can utilize a non-uniformly distributed modulation constellation to improve spectral efficiency. In some cases, wireless fading can occur in a multiple-input and multiple-output (MIMO) channel, which can result in a loss of shaping gain from probability shaping. Some examples of methods for linear MIMO demodulation using probability shaping with an auxiliary dimension are provided. A wireless device can receive information indicating a non-uniform probability distribution for a modulation constellation of a MIMO signal. One or more symbols of the MIMO signal can be transmitted or received via a channel. The wireless device can demodulate the symbols based at least in part on a transformation of the modulation constellation to a subspace using a dimension associated with the non-uniform probability distribution and a nearest point of the transformed modulation constellation to a projected symbol in the subspace.

Description

Cross-references

[0001] This patent application claims priority to U.S. Patent Application No. 18 / 607,969, filed March 18, 2024, entitled “MULTIPLE-INPUT AND MULTIPLE-OUTPUT DEMODULATION FOR NON-UNIFORM MODULATION CONSTELLATIONS”, which is assigned to the assignee of this application and is expressly incorporated herein by reference in its entirety. Technical Field

[0002] The following pertains to wireless communication, including multiple-input and multiple-output demodulation of non-uniform modulation constellations. Background Technology

[0003] Wireless communication systems are widely deployed to provide various types of communication content, such as voice, video, packet data, message sending and receiving, broadcasting, and so on. These systems can support communication with multiple users by sharing available system resources (e.g., time, frequency, and power). Examples of such multiple access systems include fourth-generation (4G) systems (such as Long Term Evolution (LTE) systems, LTE-A Advanced (LTE-A) systems, or LTE-A Pro systems) and fifth-generation (5G) systems (which may be referred to as New Radio (NR) systems). These systems may employ technologies such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal FDMA (OFDMA), or Discrete Fourier Transform Extended Orthogonal Frequency Division Multiplexing (DFT-S-OFDM). A wireless multiple access communication system may include one or more base stations, each supporting wireless communication of communication devices, which may be referred to as User Equipment (UE). Summary of the Invention

[0004] Some examples of the techniques described herein provide methods for linear multiple-input multiple-output (MIMO) demodulation using probabilistic shaping with an auxiliary dimension. A wireless device can receive information indicating a non-uniform probability distribution of a modulation constellation used for a MIMO signal. The MIMO signal can be modulated using probabilistic shaping (e.g., a modulation constellation with a non-uniform probability distribution). One or more symbols of the MIMO signal can be transmitted or received via a channel. For example, a wireless device can receive one or more symbols of a MIMO signal. The wireless device can demodulate a symbol based on a transformation of the modulation constellation to a subspace using a dimension associated with the non-uniform probability distribution and the point in the transformed modulation constellation closest to the projected symbol corresponding to the symbol in the subspace. In some aspects, the wireless device can add an auxiliary dimension to the modulation constellation to account for probabilistic shaping. For example, the modulation constellation can be transformed to a subspace using a dimension associated with the non-uniform probability distribution. The wireless device can project symbols into the subspace to generate projected symbols to determine the point in the transformed modulation constellation closest to the projected symbol in the subspace.

[0005] A method performed by a wireless device is described. The method may include: receiving information indicating a non-uniform probability distribution of a modulation constellation for a MIMO signal; receiving a symbol of the MIMO signal modulated with the non-uniform probability distribution; and demodulating the symbol based on a transformation of the modulation constellation to a subspace using a dimension associated with the non-uniform probability distribution and the point of closest projection of the transformed modulation constellation to the corresponding symbol in the subspace.

[0006] A wireless device is described. The wireless device may include: one or more memories storing processor-executable code; and one or more processors coupled to the one or more memories. The one or more processors may be able to operate individually or jointly to execute the code to cause the wireless device to: receive information indicating a non-uniform probability distribution for a modulation constellation used for a MIMO signal; receive symbols of a MIMO signal modulated with the non-uniform probability distribution; and demodulate the symbols based on a transformation of the modulation constellation to a subspace using a dimension associated with the non-uniform probability distribution and the point of nearest projection of the transformed modulation constellation to the corresponding symbol in the subspace.

[0007] Another wireless device is described. This wireless device may include: components for receiving information indicating a non-uniform probability distribution of a modulation constellation for a MIMO signal; components for receiving symbols of a MIMO signal modulated with a non-uniform probability distribution; and components for demodulating the symbols based on a transformation of the modulation constellation to a subspace using a dimension associated with the non-uniform probability distribution and the nearest point of the transformed modulation constellation to the corresponding projected symbol in the subspace.

[0008] A non-transitory computer-readable medium storing code is described. The code may include instructions executable by one or more processors to: receive information indicating a non-uniform probability distribution for a modulation constellation used for a MIMO signal; receive a symbol of the MIMO signal modulated with the non-uniform probability distribution; and demodulate the symbol based on a transformation of the modulation constellation to a subspace using a dimension associated with the non-uniform probability distribution and the point of the transformed modulation constellation closest to the projected symbol corresponding to the symbol in the subspace.

[0009] The methods, wireless devices, and some examples of nontransitory computer-readable media described herein may also include operations, features, components, or instructions for demodulating symbols by projecting the symbols into a subspace to generate projected symbols, thereby determining the point of the transformed modulation constellation closest to the projected symbol.

[0010] The methods, wireless devices, and some examples of nontransitory computer-readable media described herein may also include operations, features, components, or instructions for receiving signals to generate a channel estimate, wherein symbols are received via the channel, and wherein the transformation of the modulation constellation includes a transformation of the channel estimate and a combination of modulation constellations.

[0011] In some examples of the methods, wireless devices, and nontransitory computer-readable media described herein, the number of dimensions associated with a non-uniform probability distribution can be correlated with the number of layers in a MIMO signal.

[0012] In some examples of the methods, wireless devices, and nontransitory computer-readable media described herein, the subspace includes a number of dimensions that can be twice the number of layers of a MIMO signal, and can be associated with a space that is four times the number of layers of a MIMO signal.

[0013] The methods, wireless devices, and some examples of nontransitory computer-readable media described herein may also include operations, features, components, or instructions for decoding a non-discrete estimate of the symbol vector of a set of symbols comprising multiple symbol layers to determine the point of the transformed modulation constellation closest to the projected symbol.

[0014] In some examples of the methods, wireless devices, and nontransitory computer-readable media described herein, a non-uniform probability distribution may be associated with a first layer of a MIMO signal, and the methods, apparatus, and nontransitory computer-readable media may also include operations, features, components, or instructions for: receiving a second symbol of a second layer of a MIMO signal, the second layer of which is modulated with a second non-uniform probability distribution different from the non-uniform probability distribution associated with the first layer; and demodulating the second symbol of the second layer of the MIMO signal based on a second transformation of the modulation constellation in a second subspace using a dimension associated with the second non-uniform probability distribution and a second point of the transformed modulation constellation closest to the second symbol in the second subspace.

[0015] The methods, wireless devices, and some examples of nontransitory computer-readable media described herein may also include operations, features, components, or instructions for receiving an indication of a second non-uniform probability distribution associated with a second layer of a MIMO signal.

[0016] In some examples of the methods, wireless devices, and non-transitory computer-readable media described herein, the modulation constellation may be a quadrature amplitude modulation (QAM) constellation. Attached Figure Description

[0017] Figure 1 An example of a wireless communication system supporting multiple-input multiple-output (MIMO) demodulation of a non-uniform modulation constellation, according to one or more aspects of this disclosure, is shown.

[0018] Figure 2 An example of a wireless communication system supporting MIMO demodulation of a non-uniform modulation constellation according to one or more aspects of this disclosure is shown.

[0019] Figure 3 A diagram illustrating an example of demodulation of a modulation constellation supporting one or more aspects of this disclosure is shown.

[0020] Figure 4 A diagram illustrating an example of demodulation supporting a non-uniform modulation constellation for MIMO demodulation according to one or more aspects of this disclosure is shown.

[0021] Figure 5 An example of a process flow for MIMO demodulation supporting a non-uniform modulation constellation is shown according to one or more aspects of this disclosure.

[0022] Figure 6 and Figure 7 A block diagram of an apparatus supporting MIMO demodulation of a non-uniform modulation constellation is shown according to one or more aspects of this disclosure.

[0023] Figure 8A block diagram of a communication manager supporting MIMO demodulation of a non-uniform modulation constellation according to one or more aspects of this disclosure is shown.

[0024] Figure 9 A diagram of a system including a device supporting MIMO demodulation of a non-uniform modulation constellation, according to one or more aspects of this disclosure, is shown.

[0025] Figure 10 and Figure 11 A flowchart illustrating a method for MIMO demodulation supporting a non-uniform modulation constellation according to one or more aspects of this disclosure is shown. Detailed Implementation

[0026] Some wireless communication systems modulate signals used for transmission via a channel. For example, wireless devices may use Quadrature Amplitude Modulation (QAM) to modulate signals. Some modulation schemes use modulation constellations, where each point in the modulation constellation has a uniform probability for the modulation symbol. Probabilistic shaping can utilize non-uniformly distributed modulation constellations to improve spectral efficiency. In some methods, the Maxwell-Boltzmann (MB) distribution can be utilized, which can increase (e.g., maximize) the source entropy for a given average power. Different methods can be used to perform probabilistic shaping, such as the Constant Composition Distributed Matcher (CCDM) method with an MB distribution. Probabilistic shaping can be performed to attempt to close the shaping gap (e.g., a 1.53 dB shaping gap) toward log(1 + signal-to-noise ratio (SNR)) on an additive white Gaussian noise (AWGN) channel.

[0027] In some cases, radio fading can occur in multiple-input multiple-output (MIMO) channels, potentially leading to a loss of shaping gain from probabilistic shaping. For example, some methods for linear MIMO demodulation can be performed using linear methods such as zero-forcing or linear minimum mean square error (MMSE) techniques, which may not fully realize the shaping gain from probabilistic shaping. In some variations of linear MIMO demodulation, the inverse (or pseudo-inverse of a non-matrix) or regularized version of the channel (e.g., via linear MMSE) can first be applied to the corresponding (e.g., individual and distinct) MIMO layer of the received signal, and then single-input single-output (SISO) demodulation can be performed independently for each layer. Performing linear demodulation in this manner may waste the gain from probabilistic shaping and may exhibit some performance loss compared to linear demodulation of older QAM constellations. Therefore, a linear demodulation scheme that improves the performance of probabilistic shaping constellations is needed.

[0028] This paper provides some examples of methods for linear MIMO demodulation using probabilistic shaping with auxiliary dimensions. A wireless device can receive information indicating a non-uniform probability distribution of a modulation constellation used for a MIMO signal. The MIMO signal can be modulated using probabilistic shaping (e.g., a modulation constellation with a non-uniform probability distribution). One or more symbols of the MIMO signal can be transmitted or received via a channel. For example, the wireless device can receive one or more symbols of a MIMO signal. The wireless device can demodulate the symbol based on a transformation of the modulation constellation to a subspace using a dimension associated with the non-uniform probability distribution and the point in the transformed modulation constellation closest to the projected symbol corresponding to the symbol in the subspace. In some aspects, the wireless device can add auxiliary dimensions to the modulation constellation to account for probabilistic shaping. For example, the modulation constellation can be transformed to a subspace using a dimension associated with the non-uniform probability distribution. The wireless device can project the symbol into the subspace to generate projected symbols to determine the point in the transformed modulation constellation closest to the projected symbol in the subspace.

[0029] Considering non-uniform probability distributions with auxiliary dimensions can provide improved demodulation performance and spectral efficiency for modulation constellations with non-uniform probability distributions. For example, using an additional dimension during demodulation can achieve improved spectral efficiency while avoiding wasting the gain from probability shaping that would occur when performing SISO demodulation independently for each layer.

[0030] In some methods, different probability distributions can be used for different layers of the MIMO signal due to one or more SNR gaps between different MIMO layers; this can occur in a variety of scenarios. Some examples of demodulation methods using different distributions and modulation sizes for different MIMO layers are provided.

[0031] The aspects of this disclosure are first described in the context of a wireless communication system. The aspects of this disclosure are also described in the context of diagrams illustrating examples of demodulation. Additionally, the aspects of this disclosure are described in the context of a process flow. The aspects of this disclosure are further illustrated and described with reference to apparatus diagrams, system diagrams, and flowcharts related to MIMO demodulation of non-uniform modulation constellations.

[0032] Figure 1An example of a wireless communication system 100 supporting MIMO demodulation of a non-uniform modulation constellation according to one or more aspects of this disclosure is shown. The wireless communication system 100 may include one or more devices, such as one or more network devices (e.g., network entity 105), one or more UEs 115, and a core network 130. In some examples, the wireless communication system 100 may be a Long Term Evolution (LTE) network, an Advanced LTE (LTE-A) network, an LTE-A Pro network, a New Radio (NR) network, or a network operating under other systems and radio technologies including future systems and radio technologies not explicitly mentioned herein.

[0033] Network entity 105 may be distributed across a geographical area to form wireless communication system 100, and may include devices employing different forms or having different capabilities. In various examples, network entity 105 may be referred to as a network element, mobility element, radio access network (RAN) node, or network equipment, etc. In some examples, network entity 105 and UE 115 may wirelessly communicate via communication link 125 (e.g., a radio frequency (RF) access link). For example, network entity 105 may support coverage area 110 (e.g., a geographical coverage area) within which UE 115 and network entity 105 may establish communication link 125. Coverage area 110 may be an example of a geographical area within which network entity 105 and UE 115 may support the transmission of signals according to one or more radio access technologies (RATs).

[0034] UE 115 can be distributed throughout the coverage area 110 of wireless communication system 100, and each UE 115 can be stationary or mobile, or stationary and mobile at different times. UE 115 can be devices in different forms or with different capabilities. Figure 1 Examples of UE 115 are illustrated herein. The UE 115 described herein may be able to support communication with various types of devices in the wireless communication system 100 (e.g., other wireless communication devices, including UE 115 or network entity 105), such as... Figure 1 As shown.

[0035] As described herein, nodes of the wireless communication system 100 (which may be referred to as network nodes or wireless nodes) may be network entity 105 (e.g., any network entity described herein), UE 115 (e.g., any UE described herein), network controller, apparatus, device, computing system, one or more components, or another suitable processing entity configured to perform any of the techniques described herein. For example, a node may be UE 115. Alternatively, a node may be network entity 105. Furthermore, a first node may be configured to communicate with a second or third node. In one aspect of this example, the first node may be UE 115, the second node may be network entity 105, and the third node may be UE 115. In another aspect of this example, the first node may be UE 115, the second node may be network entity 105, and the third node may be network entity 105. In other aspects of this example, the first node, the second node, and the third node may be different from these examples. Similarly, references to UE 115, network entity 105, device, equipment, computing system, etc., may include disclosures of UE 115, network entity 105, device, equipment, computing system, etc., as nodes. For example, a disclosure that UE 115 is configured to receive information from network entity 105 also discloses that a first node is configured to receive information from a second node.

[0036] In some examples, network entity 105 may communicate with core network 130, or with each other, or both. For example, network entity 105 may communicate with core network 130 via backhaul communication link 120 (e.g., according to S1, N2, N3, or other interface protocols). In some examples, network entities 105 may communicate with each other directly (e.g., directly between network entities 105) or indirectly (e.g., via core network 130) via backhaul communication link 120 (e.g., according to X2, Xn, or other interface protocols). In some examples, network entities 105 may communicate with each other via midhaul communication link 162 (e.g., according to midhaul interface protocol) or fronthaul communication link 168 (e.g., according to fronthaul interface protocol) or any combination thereof. Backhaul communication link 120, midhaul communication link 162, or fronthaul communication link 168 may be or include one or more wired links (e.g., electrical links, fiber optic links), or one or more wireless links (e.g., radio links, wireless optical links), etc., or various combinations thereof. UE 115 can communicate with core network 130 via communication link 155.

[0037] One or more of the network entities 105 or network equipment described herein may include or be referred to as base station 140 (e.g., transceiver base station, radio base station, NR base station, access point, radio transceiver, node B, eNodeB (eNB), next-generation node B or gigabit node B (any of which may be referred to as gNB), 5G NB, next-generation eNB (ng-eNB), home node B, home evolution node B, or other suitable terms). In some examples, network entity 105 (e.g., base station 140) may be implemented in an aggregated (e.g., monolithic, standalone) base station architecture that may be configured to utilize a protocol stack that is physically or logically integrated within a single network entity (e.g., network entity 105 or a single RAN node, such as base station 140).

[0038] In some examples, network entity 105 may be implemented in a decomposed architecture (e.g., a decomposed base station architecture, a decomposed RAN architecture) that can be configured to utilize protocol stacks physically or logically distributed across multiple network entities (e.g., network entity 105) such as an Integrated Access and Backhaul (IAB) network, an Open RAN (O-RAN) (e.g., a network configuration sponsored by the O-RAN Alliance), or a Virtualized RAN (vRAN) (e.g., a Cloud RAN (C-RAN)). For example, network entity 105 may include one or more of the following: a Central Unit (CU) such as CU 160, a Distributed Unit (DU) such as DU 165, a Radio Unit (RU) such as RU 170, a RAN Intelligent Controller (RIC) such as RIC 175 (e.g., a near real-time RIC (near RT RIC), a non-real-time RIC (non-RT RIC)), a Service Management and Orchestration (SMO) system such as SMO system 180, or any combination thereof. RU170 may also be referred to as a radio headend, intelligent radio headend, remote radio headend (RRH), remote radio unit (RRU), or transmit / receive point (TRP). One or more components of network entity 105 in a decomposed RAN architecture may be co-located, or one or more components of network entity 105 may be located in distributed locations (e.g., separate physical locations). In some examples, one or more network entities in network entity 105 of a decomposed RAN architecture may be implemented as virtual units (e.g., virtual CU (VCU), virtual DU (VDU), virtual RU (VRU)).

[0039] The functional splitting among CU 160, DU 165, and RU 170 is flexible and can support different functionalities depending on which functions (e.g., network layer functions, protocol layer functions, baseband functions, RF functions, or any combination thereof) are performed at CU 160, DU 165, or RU 170. For example, a protocol stack functional splitting can be used between CU 160 and DU 165, allowing CU 160 to support one or more layers of the protocol stack, and DU 165 to support one or more different layers of the protocol stack. In some examples, CU 160 can host higher protocol layer (e.g., Layer 3 (L3), Layer 2 (L2)) functionalities and signaling (e.g., Radio Resource Control (RRC), Serving Data Adaptation Protocol (SDAP), Packet Data Convergence Protocol (PDCP)). CU 160 (e.g., one or more CUs) may connect to DU 165 (e.g., one or more DUs) or RU 170 (e.g., one or more RUs) or some combination thereof, and DU 165, RU 170, or both may host lower protocol layers, such as Layer 1 (L1) (e.g., Physical (PHY) layer) or L2 (e.g., Radio Link Control (RLC) layer, Medium Access Control (MAC) layer) functionality and signaling, and may each be at least partially controlled by CU 160. Additionally or alternatively, a functional split of the protocol stack may be employed between DU 165 and RU 170, such that DU 165 may support one or more layers of the protocol stack, and RU 170 may support one or more different layers of the protocol stack. DU 165 may (e.g., via one or more different RUs, such as RU 170) support one or more different cells. In some cases, functional decomposition between CU 160 and DU 165, or between DU 165 and RU 170, can be performed within the protocol layer (e.g., some functions of the protocol layer can be performed by one of CU 160, DU 165, or RU 170, while other functions of the protocol layer can be performed by a different one of CU 160, DU 165, or RU 170). CU 160 can be further functionally decomposed into CU control plane (CU-CP) functions and CU user plane (CU-UP) functions. CU 160 can be connected to DU 165 via midhaul communication link 162 (e.g., F1, F1-c, F1-u), and DU 165 can be connected to RU 170 via fronthaul communication link 168 (e.g., open fronthaul (FH) interface). In some examples, the midhaul communication link 162 or the fronthaul communication link 168 may be implemented based on the interfaces (e.g., channels) between the layers of the protocol stack, which are supported by corresponding network entities (e.g., one or more network entities in network entity 105) that communicate via such communication links.

[0040] In some wireless communication systems (e.g., wireless communication system 100), the infrastructure and spectrum resources for radio access can support wireless backhaul link capabilities to supplement wired backhaul connections, thereby providing an IAB network architecture (e.g., to core network 130). In some cases, in an IAB network, one or more network entities in network entity 105 (e.g., network entity 105 or IAB node 104) may be partially controlled by each other. IAB node 104 may be referred to as a donor entity or IAB donor. DU 165 or RU 170 may be partially controlled by CU 160 associated with network entity 105 or base station 140 (such as a donor network entity or donor base station). One or more donor entities (e.g., IAB donors) may communicate with one or more additional devices (e.g., IAB node 104) via supported access and backhaul links (e.g., backhaul communication link 120). IAB node 104 may include IAB mobile terminals (IAB-MTs) controlled (e.g., scheduled) by one or more DUs (e.g., DU 165) of a coupled IAB donor. IAB-MTs may be equipped with a separate set of antennas for relaying communication with UE 115, or may share the same antennas (e.g., those of RU 170) for access to IAB node 104 via DU 165 of IAB node 104. (e.g., referred to as virtual IAB-MT (vIAB-MT)). In some examples, IAB node 104 may include one or more DUs (e.g., DU 165) that support communication links with additional entities (e.g., IAB node 104, UE 115) within a relay chain or configuration (e.g., downstream) of the access network. In such cases, one or more components of the decomposed RAN architecture (e.g., IAB node 104, or components of IAB node 104) may be configured to operate according to the techniques described herein.

[0041] For example, the access network (AN) or RAN may include communication between an access node (e.g., an IAB donor), IAB node 104, and one or more UEs 115. The IAB donor may facilitate connectivity between the core network 130 and the AN (e.g., via a wired or wireless connection to the core network 130). That is, an IAB donor may refer to a RAN node having a wired or wireless connection to the core network 130. The IAB donor may include one or more of CU 160, DU 165, and RU 170, in which case CU 160 may communicate with the core network 130 via an interface (e.g., a backhaul link). The IAB donor and IAB node 104 may communicate via an F1 interface according to a protocol defining the signaling messages (e.g., the F1 AP protocol). Additionally or alternatively, CU 160 may communicate with core network 130 via an interface (which may be part of a backhaul link) and may communicate with other CUs (e.g., including CU 160 associated with an alternative IAB donor) via an Xn-C interface (which may be another part of a backhaul link).

[0042] IAB node 104 may refer to a RAN node that provides IAB functionality (e.g., access for UE 115, radio self-backhaul capability, etc.). DU 165 may act as a distributed scheduling node toward child nodes associated with IAB node 104, and IAB-MT may act as a scheduled node toward a parent node associated with IAB node 104. That is, an IAB donor may be referred to as a parent node communicating with one or more child nodes (e.g., an IAB donor may be relayed by other IAB nodes 104 for UE transmission). Additionally or alternatively, IAB node 104 may also be referred to as a parent or child node of other IAB nodes 104, depending on the AN's relay chain or configuration. The IAB-MT entity of IAB node 104 can provide a Uu interface for child IAB nodes (e.g., IAB node 104) to receive signaling from parent IAB nodes (e.g., IAB node 104), and the DU interface (e.g., DU 165) can provide a Uu interface for parent IAB nodes to send signals to child IAB nodes or UE 115.

[0043] For example, IAB node 104 may be referred to as a parent node supporting communication to child IAB nodes, or as a child IAB node associated with an IAB donor, or both. An IAB donor may include a CU 160 having a wired or wireless connection to core network 130 (e.g., backhaul communication link 120) and may act as a parent node of IAB node 104. For example, an IAB donor's DU 165 may relay transmissions to UE 115 via IAB node 104, or may signal transmissions directly to UE 115, or both. An IAB donor's CU 160 may signal the establishment of a communication link to IAB node 104 via an F1 interface, and IAB node 104 may schedule transmissions (e.g., transmissions relayed from the IAB donor to UE 115) via one or more DUs (e.g., DU 165). In other words, data can be relayed to and from IAB node 104 via signaling through the NR Uu interface of the MT to IAB node 104 (e.g., other IAB nodes). Communication with IAB node 104 can be scheduled by the DU 165 of the IAB donor or the DU 165 of IAB node 104.

[0044] When the techniques described herein are applied in the context of a decomposed RAN architecture, one or more components of the decomposed RAN architecture may be configured to support the tests described herein. For example, some operations described as being performed by UE 115 or network entity 105 (e.g., base station 140) may additionally or alternatively be performed by one or more components of the decomposed RAN architecture (e.g., components such as IAB node, DU 165, CU 160, RU 170, RIC 175, SMO system 180).

[0045] UE 115 may include or be referred to as a mobile device, wireless device, remote device, handheld device, or subscriber device, or any other suitable term, wherein "device" may also be referred to as a cell, station, terminal, or client, etc. UE 115 may also include or be referred to as a personal electronic device, such as a cellular phone, personal digital assistant (PDA), tablet computer, laptop computer, or personal computer. In some examples, UE 115 may include or be referred to as a wireless local loop (WLL) station, Internet of Things (IoT) device, Internet of Everything (IoE) device, or machine-type communication (MTC) device, etc., which may be implemented in various objects such as appliances, vehicles, or meters.

[0046] The UE 115 described herein may be able to communicate with various types of devices, such as the UE 115 which may sometimes operate as a relay, as well as network entity 105 and network equipment including macro eNBs or gNBs, small cell eNBs or gNBs, or relay base stations, etc. Figure 1 As shown.

[0047] UE 115 and network entity 105 can wirelessly communicate with each other via communication link 125 (e.g., one or more access links) using resources associated with one or more carriers. The term "carrier" can refer to a collection of RF spectrum resources having a defined PHY layer structure for supporting communication link 125. For example, a carrier for communication link 125 may include a portion of the RF spectrum band (e.g., a bandwidth portion (BWP)) operating according to one or more PHY layer channels for a given RAT (e.g., LTE, LTE-A, LTE-A Pro, NR). Each PHY layer channel may carry acquisition signaling (e.g., synchronization signals, system information), control signaling coordinating operation for the carrier, user data, or other signaling. Wireless communication system 100 can support communication with UE 115 using carrier aggregation or multi-carrier operation. Depending on the carrier aggregation configuration, UE 115 can be configured to utilize multiple downlink component carriers and one or more uplink component carriers. Carrier aggregation can be used in conjunction with both frequency division duplex (FDD) component carriers and time division duplex (TDD) component carriers. Communication between network entity 105 and other devices can refer to communication between these devices and any part of network entity 105 (e.g., entity, sub-entity). For example, the terms “send,” “receive,” or “communicate” when referring to network entity 105 can refer to any part of the RAN’s network entity 105 (e.g., base station 140, CU 160, DU 165, RU 170) communicating with another device (e.g., directly or via one or more other network entities, such as one or more network entities in network entity 105).

[0048] In some examples, such as in carrier aggregation configurations, carriers may have acquisition or control signaling that coordinates operation against other carriers. Carriers may be associated with a frequency channel (e.g., an Evolved Universal Mobile Telecommunications System Terrestrial Radio Access (E-UTRA) Absolute RF Channel Number (EARFCN)) and may be identified according to a channel grating used for discovery by UE 115. Carriers may operate in standalone mode, in which case initial acquisition and connection can be performed by UE 115 via that carrier, or carriers may operate in non-standalone mode, in which case different carriers (e.g., of the same or different RATs) are used to anchor the connection.

[0049] The communication link 125 of the wireless communication system 100 may include downlink transmission (e.g., forward link transmission) from network entity 105 to UE 115, uplink transmission (e.g., return link transmission) from UE 115 to network entity 105, or both, as well as other transmission configurations. The carrier may carry downlink communication or uplink communication (e.g., in FDD mode), or may be configured to carry both downlink and uplink communication (e.g., in TDD mode).

[0050] A carrier may be associated with a specific bandwidth of the RF spectrum, and in some examples, the carrier bandwidth may be referred to as the carrier or the “system bandwidth” of the wireless communication system 100. For example, the carrier bandwidth may be one of a set of bandwidths for a carrier for a specific RAT (e.g., 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz, 20 MHz, 40 MHz, or 80 MHz). Devices of the wireless communication system 100 (e.g., network entity 105, UE 115, or both) may have hardware configurations that support communication using a specific carrier bandwidth, or may be configured to support communication using one of a set of carrier bandwidths. In some examples, the wireless communication system 100 may include network entity 105 or UE 115 that supports concurrent communication using carriers associated with multiple carrier bandwidths. In some examples, each served UE 115 may be configured to operate using a portion (e.g., subband, BWP) or all of the carrier bandwidth.

[0051] The signal waveform transmitted via a carrier may include multiple subcarriers (e.g., using multi-carrier modulation (MCM) techniques, such as orthogonal frequency division multiplexing (OFDM) or discrete Fourier transform extended OFDM (DFT-S-OFDM)). In a system employing MCM, a resource element may refer to a resource of one symbol period (e.g., the duration of one modulation symbol) and one subcarrier, where the symbol period and subcarrier spacing may be inversely related. The number of bits carried by each resource element may depend on the modulation scheme (e.g., the order of the modulation scheme, the decoding rate of the modulation scheme, or both), such that a relatively high number of resource elements (e.g., in the transmission duration) and a relatively high modulation scheme order correspond to a relatively high communication rate. Wireless communication resources may refer to a combination of RF spectrum resources, temporal resources, and spatial resources (e.g., spatial layers or beams), and the use of multiple spatial resources may increase the data rate or data integrity used for communication with UE 115.

[0052] It can support one or more sets of parameters for a carrier, and the set of parameters may include subcarrier spacing ( (and cyclic prefix). A carrier can be divided into one or more BWPs with the same or different sets of parameters. In some examples, UE 115 can be configured to utilize multiple BWPs. In some examples, a single BWP of a carrier can be active at a given time, and communication for UE 115 can be constrained to one or more active BWPs.

[0053] The time interval for network entity 105 or UE 115 can be expressed as a multiple of a basic time unit, such as the sampling period. seconds, in response This can represent the supported subcarrier spacing, and The supported Discrete Fourier Transform (DFT) size can be represented. Time intervals for communication resources can be organized according to radio frames, each with a specified duration (e.g., 10 milliseconds (ms)). Each radio frame can be identified by a System Frame Number (SFN) (e.g., ranging from 0 to 1023).

[0054] Each frame may include multiple consecutively numbered subframes or time slots, and each subframe or time slot may have the same duration. In some examples, a frame may (e.g., in the time domain) be divided into subframes, and each subframe may also be divided into a number of time slots. Alternatively, each frame may include a variable number of time slots, and the number of time slots may depend on the subcarrier spacing. Each time slot may include a number of symbol periods (e.g., depending on the length of the cyclic prefix appended to each symbol period). In some wireless communication systems, such as wireless communication system 100, time slots may be further divided into multiple micro-time slots associated with one or more symbols. Excluding the cyclic prefix, each symbol period may be associated with one or more (e.g., The duration of a symbol period is associated with a (number) sampling period. The duration of a symbol period can depend on the subcarrier spacing or the operating frequency band.

[0055] A subframe, time slot, micro-time slot, or symbol can be the smallest scheduling unit of the wireless communication system 100 (e.g., in the time domain) and can be referred to as a transmission time interval (TTI). In some examples, the duration of the TTI (e.g., the number of symbol periods in the TTI) can be variable. Additionally or alternatively, the smallest scheduling unit of the wireless communication system 100 can be dynamically selected (e.g., in a burst of shortened TTIs (sTTIs)).

[0056] Depending on the technology, carriers can be used to multiplex physical channels for communication. For example, one or more of Time Division Multiplexing (TDM), Frequency Division Multiplexing (FDM), or hybrid TDM-FDM techniques can be used to multiplex physical control channels and physical data channels for signaling via a downlink carrier. The control region (e.g., control resource set (CORESET)) of the physical control channel may be defined by a set of symbol periods and may extend across the system bandwidth of the carrier or a subset of that bandwidth. One or more control regions (e.g., CORESET) can be configured for a set of UEs 115. For example, one or more UEs in UE 115 may monitor or search for control regions to obtain control information based on one or more search space sets, and each search space set may include one or more control channel candidates in one or more aggregation levels arranged in a concatenated manner. The aggregation level of control channel candidates may refer to the amount of control channel resources (e.g., control channel elements (CCEs)) associated with coded information for a control information format having a given payload size. The search space set may include a public search space set configured to transmit control information to UE115 (e.g., one or more UEs) or a UE-specific search space set configured to transmit control information to UE115 (e.g., a particular UE).

[0057] Network entity 105 may provide communication coverage via one or more cells (e.g., macro cells, small cells, hotspots, or other types of cells, or any combination thereof). The term "cell" may refer to a logical communication entity used (e.g., using a carrier) to communicate with network entity 105 and may be associated with an identifier used to distinguish adjacent cells (e.g., Physical Cell Identifier (PCID), Virtual Cell Identifier (VCID)). In some examples, a cell may also refer to a coverage area 110 or a portion of coverage area 110 (e.g., a sector) in which a logical communication entity operates. Depending on various factors such as the capabilities of network entity 105, the range of such cells may be from smaller areas (e.g., structures, subsets of structures) to larger areas. For example, a cell may be a building, a subset of buildings, or external space between or overlapping coverage areas 110, etc., or may include buildings, subsets of buildings, or external space between or overlapping coverage areas, etc.

[0058] Macro cells typically cover a relatively large geographic area (e.g., a radius of several kilometers) and allow unrestricted access to UE 115 that has a service subscription with a network provider supporting the macro cell. In contrast to macro cells, small cells may be associated with network entities 105 operating at lower power (e.g., base station 140 operating at lower power) and may operate using the same or different (e.g., licensed, unlicensed) frequency bands as macro cells. Small cells may provide unrestricted access to UE 115 that has a service subscription with a network provider, or restricted access to UE 115 associated with a small cell (e.g., UE 115 in a closed subscriber group (CSG), or UE 115 associated with a user in a home or office). Network entity 105 may support one or more cells and may also support communication via one or more cells using one or more component carriers.

[0059] In some examples, a carrier can support multiple cells and can be configured with different cells based on different protocol types that can provide access for different types of devices (e.g., MTC, Narrowband IoT (NB-IoT), Enhanced Mobile Broadband (eMBB)).

[0060] In some examples, network entity 105 (e.g., base station 140, RU 170) may be mobile, and thus provide communication coverage to mobile coverage areas such as coverage area 110. In some examples, coverage areas 110 associated with different technologies (e.g., different coverage areas) may overlap, but coverage areas 110 (e.g., different coverage areas) may be supported by the same network entity (e.g., network entity 105). In some other examples, overlapping coverage areas such as coverage area 110 associated with different technologies may be supported by different network entities (e.g., network entity 105). Wireless communication system 100 may include, for example, a heterogeneous network in which different types of network entities 105 use the same or different RATs to support communication for coverage areas 110 (e.g., different coverage areas).

[0061] The wireless communication system 100 can support synchronous or asynchronous operation. For synchronous operation, network entities 105 (e.g., base station 140) can have similar frame timing, and transmissions from different network entities (e.g., different network entities within network entity 105) can be roughly aligned in time. For asynchronous operation, network entities 105 can have different frame timing, and in some examples, transmissions from different network entities (e.g., different network entities within network entity 105) may not be aligned in time. The techniques described herein can be used for both synchronous and asynchronous operation.

[0062] Some UE 115 devices (such as MTC or IoT devices) can be relatively low-cost or low-complexity devices and can provide automated communication between machines (e.g., via machine-to-machine (M2M) communication). M2M communication or MTC can refer to data communication technologies that allow devices to communicate with each other or with network entity 105 (e.g., base station 140) without human intervention. In some examples, M2M communication or MTC may include communication from devices with integrated sensors or instruments to measure or acquire information and relay such information to a central server or application that uses the information or presents it to people interacting with the application. Some UE 115 devices may be designed to collect information or enable automated behavior of machines or other devices. Examples of applications for MTC devices include smart metering, inventory monitoring, water level monitoring, equipment monitoring, healthcare monitoring, wildlife monitoring, weather and geological event monitoring, fleet management and tracking, remote security sensing, physical access control, and transaction-based service charging.

[0063] Some UE 115s can be configured to operate in reduced-power modes, such as half-duplex communication (e.g., a mode that supports unidirectional communication via transmission or reception but does not transmit and receive concurrently). In some examples, half-duplex communication can be performed at reduced peak rates. Other power-saving techniques for UE 115 may include entering a power-saving deep sleep mode when not engaged in active communication, operating with limited bandwidth (e.g., according to narrowband communication), or a combination of these techniques. For example, some UE 115s may be configured to operate using a narrowband protocol type associated with a defined portion or range (e.g., a set of subcarriers or resource blocks (RBs)) within a carrier, within a carrier's guard band, or outside a carrier.

[0064] Wireless communication system 100 may be configured to support ultra-reliable communication or low-latency communication, or various combinations thereof. For example, wireless communication system 100 may be configured to support ultra-reliable low-latency communication (URLLC). UE 115 may be designed to support ultra-reliable, low-latency, or critical functions. Ultra-reliable communication may include private or group communication and may be supported by one or more services, such as push-to-talk, video, or data. Support for ultra-reliable, low-latency functions may include prioritizing services, and such services may be used for public safety or general business applications. The terms “ultra-reliable,” “low-latency,” and “ultra-reliable low-latency” are used interchangeably herein.

[0065] In some examples, UE 115 may be configured to support direct communication with other UEs (e.g., one or more UEs in UE 115) via a device-to-device (D2D) communication link (such as D2D communication link 135) (e.g., according to a peer-to-peer (P2P), D2D, or sidelink protocol). In some examples, one or more UEs 115 in a group performing D2D communication may be within the coverage area 110 of network entity 105 (e.g., base station 140, RU 170), which may support aspects of such D2D communication configured (e.g., scheduled by network entity 105). In some examples, one or more UEs 115 in such a group may be outside the coverage area 110 of network entity 105, or may otherwise be unable or not configured to receive transmissions from network entity 105. In some examples, a group of UEs 115 communicating via D2D communication can support a one-to-many (1:M) system, in which each UE 115 transmits to one or more UEs within the group. In some examples, network entity 105 can facilitate the scheduling of resources used for D2D communication. In some other examples, D2D communication can be performed between UEs 115 without involving network entity 105.

[0066] In some systems, the D2D communication link 135 may be an example of a communication channel (such as a sidelink communication channel) between vehicles (e.g., UE 115). In some examples, vehicles may communicate using vehicle-to-vehicle (V2X) communication, vehicle-to-vehicle (V2V) communication, or some combination of these. Vehicles may signal information related to traffic conditions, signaling, weather, safety, emergencies, or any other information relevant to the V2X system. In some examples, vehicles in a V2X system may communicate with roadside infrastructure (such as roadside units), or communicate with the network via one or more network nodes (e.g., network entity 105, base station 140, RU 170) using vehicle-to-network (V2N) communication, or both.

[0067] Core network 130 provides user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. Core network 130 can be an evolved packet core (EPC) or a 5G core (5GC), which may include at least one control plane entity (e.g., a mobility management entity (MME), access and mobility management function (AMF)) for managing access and mobility, and at least one user plane entity (e.g., a serving gateway (S-GW), packet data network (PDN) gateway (P-GW), or user plane function (UPF)) for routing packets or interconnecting to external networks. The control plane entity manages non-access stratum (NAS) functions, such as mobility, authentication, and bearer management of UE 115 served by network entity 105 (e.g., base station 140) associated with core network 130. User IP packets can be transferred through user plane entities, which provide IP address allocation and other functions. User plane entities can connect to one or more network operator IP services 150. IP services 150 may include access to the Internet, intranets, IP Multimedia Subsystem (IMS), or packet-switched streaming services.

[0068] Wireless communication system 100 can operate using one or more frequency bands in the range of 300 MHz to 300 GHz. Generally, the area from 300 MHz to 3 GHz is referred to as the Ultra High Frequency (UHF) band or decimeter band because the wavelength range is approximately one decimeter to one meter in length. UHF waves may be blocked or redirected by buildings and environmental features (which may be referred to as clusters), but these waves are sufficient to penetrate structures so that macrocells can provide service to UE 115 located indoors. Compared to communication using smaller frequencies and longer wavelengths in the lower frequency (HF) or very high frequency (VHF) portions of the spectrum below 300 MHz, communication using UHF waves can be associated with smaller antennas and shorter ranges (e.g., less than one hundred kilometers).

[0069] The wireless communication system 100 can also operate in the ultra-high frequency (SHF) region (also known as the centimeter band) in the range of 3 GHz to 30 GHz or in the extremely high frequency (EHF) region (e.g., 30 GHz to 300 GHz) (also known as the millimeter band) using the spectrum. In some examples, the wireless communication system 100 can support millimeter-wave (mmW) communication between the UE 115 and network entity 105 (e.g., base station 140, RU 170), and the EHF antennas of the corresponding devices can be smaller and closer together than UHF antennas. In some examples, such techniques facilitate the use of antenna arrays within the device. However, compared to SHF or UHF transmission, EHF transmission may experience even greater attenuation and shorter distances. The techniques disclosed herein can be adopted for transmission across one or more different frequency regions, and the frequency band usage specified across these frequency regions may vary by country or regulatory authority.

[0070] Wireless communication system 100 may utilize both licensed and unlicensed RF spectrum bands. For example, wireless communication system 100 may employ licensed assisted access (LAA), LTE-Unlicensed (LTE-U) RAT, or NR technology using unlicensed frequency bands (such as the 5 GHz Industrial, Scientific, and Medical (ISM) band). When operating with unlicensed RF spectrum, devices such as network entity 105 and UE 115 may employ carrier sensing for collision detection and avoidance. In some examples, operation using unlicensed frequency bands may be based on carrier aggregation configurations combined with component carriers operating with licensed frequency bands (e.g., LAA). Operation using unlicensed spectrum may include downlink transmission, uplink transmission, P2P transmission, or D2D transmission, etc.

[0071] Network entity 105 (e.g., base station 140, RU 170) or UE 115 may be equipped with multiple antennas that can be used to employ techniques such as transmit diversity, receive diversity, MIMO communication, or beamforming. The antennas of network entity 105 or UE 115 may be located within one or more antenna arrays or antenna panels, which can support MIMO operation or transmit or receive beamforming. For example, one or more base station antennas or antenna arrays may be co-located at an antenna assembly (such as an antenna tower). In some examples, the antennas or antenna arrays associated with network entity 105 may be located at different geographical locations. Network entity 105 may include an antenna array having a collection of multiple rows and columns of antenna ports that network entity 105 can use to support beamforming for communication with UE 115. Similarly, UE 115 may include one or more antenna arrays that can support various MIMO or beamforming operations. Additionally or alternatively, the antenna panel may support RF beamforming for signals transmitted via the antenna ports.

[0072] Network entity 105 or UE 115 can use MIMO communication to leverage multipath signal propagation and improve spectral efficiency by transmitting or receiving multiple signals via different spatial layers. This technique is known as spatial multiplexing. The multiple signals can be transmitted, for example, by a transmitting device via different antennas or different combinations of antennas. Similarly, the multiple signals can be received by a receiving device via different antennas or different combinations of antennas. Each of the multiple signals can be referred to as a separate spatial stream and can carry information associated with the same data stream (e.g., the same codeword) or different data streams (e.g., different codewords). Different spatial layers can be associated with different antenna ports used for channel measurement and reporting. MIMO techniques include: single-user MIMO (SU-MIMO), where multiple spatial layers are transmitted to the same receiving device; and multi-user MIMO (MU-MIMO), where multiple spatial layers are transmitted to multiple devices.

[0073] Beamforming (also known as spatial filtering, directional transmission, or directional reception) is a signal processing technique that can be used at a transmitting or receiving device (e.g., network entity 105, UE 115) to shape or guide an antenna beam (e.g., a transmit beam, a receive beam) along a spatial path between the transmitting and receiving devices. Beamforming can be achieved by combining signals transmitted via antenna elements of an antenna array such that some signals propagating along a particular orientation relative to the antenna array experience constructive interference, while other signals experience destructive interference. Adjustments to the signals transmitted via the antenna elements may include applying amplitude shifts, phase shifts, or both to the signals carried via the antenna elements associated with the device. The adjustments associated with each of these antenna elements may be defined by a beamforming weight set associated with a particular orientation (e.g., relative to the antenna array of the transmitting or receiving device or for some other orientation).

[0074] Network entity 105 or UE 115 may use beam scanning technology as part of beamforming operations. For example, network entity 105 (e.g., base station 140, RU 170) may use multiple antennas or antenna arrays (e.g., antenna panels) to perform beamforming operations for directional communication with UE 115. Some signals (e.g., synchronization signals, reference signals, beam selection signals, or other control signals) may be transmitted multiple times by network entity 105 in different directions. For example, network entity 105 may transmit signals according to different beamforming weight sets associated with different transmission directions. Beam directions may be identified (e.g., by a transmitting device (such as network entity 105) or by a receiving device (such as UE 115)) by transmission along different beam directions for later transmission or reception by network entity 105.

[0075] Some signals (such as data signals associated with a specific receiving device) may be transmitted by a transmitting device (e.g., network entity 105 or UE 115) along a single beam direction (e.g., the direction associated with a receiving device (such as another network entity 105 or UE 115). In some examples, the beam direction associated with transmission along a single beam direction may be determined based on the signals transmitted along one or more beam directions. For example, UE 115 may receive one or more signals transmitted by network entity 105 in different directions and may report to network entity 105 an indication of signals received by UE 115 with the highest signal quality or other acceptable signal quality.

[0076] In some examples, transmissions performed by a device (e.g., network entity 105 or UE 115) may be performed using multiple beam directions, and the device may use a combination of digital pre-decoding or beamforming to generate a combined beam for transmission (e.g., from network entity 105 to UE 115). UE 115 may report feedback indicating pre-decoding weights for one or more beam directions, and this feedback may correspond to a configured set of beams across the system bandwidth or one or more sub-bands. Network entity 105 may transmit reference signals (e.g., cell-specific reference signals (CRS), channel state information reference signals (CSI-RS)) that may or may not be pre-decoded. UE 115 may provide feedback for beam selection, which may be a pre-decoding matrix indicator (PMI) or codebook-based feedback (e.g., multi-panel codebook, linear combination codebook, port selection codebook). Although these techniques are described with reference to signals transmitted by network entity 105 (e.g., base station 140, RU 170) along one or more directions, UE 115 may use similar techniques to transmit signals multiple times along different directions (e.g., to identify the beam direction used by UE 115 for subsequent transmission or reception), or to transmit signals along a single direction (e.g., to transmit data to a receiving device).

[0077] A receiving device (e.g., UE 115) may perform reception operations according to multiple reception configurations (e.g., directional listening) when receiving various signals (such as synchronization signals, reference signals, beam selection signals, or other control signals) from a transmitting device (e.g., network entity 105). For example, the receiving device may perform reception according to multiple reception directions by: receiving via different antenna subarrays; processing the received signal according to different antenna subarrays; receiving according to different sets of reception beamforming weights applied to signals received at multiple antenna elements of the antenna array (e.g., different directional listening weight sets); or processing the received signal according to different sets of reception beamforming weights applied to signals received at multiple antenna elements of the antenna array. Any of these operations may be referred to as “listening” according to different reception configurations or reception directions. In some examples, the receiving device may use a single reception configuration to receive along a single beam direction (e.g., when a data signal is received). A single receiver configuration can be aligned along a beam direction determined by listening according to different receiver configuration directions (e.g., a beam direction determined to have the highest signal strength, highest signal-to-noise ratio (SNR), or other acceptable signal quality based on listening according to multiple beam directions).

[0078] The wireless communication system 100 can be a packet-based network operating according to a layered protocol stack. In the user plane, communication at the bearer or PDCP layer can be IP-based. The RLC layer performs packet segmentation and reassembly for transmission via logical channels. The MAC layer performs priority processing and multiplexing of logical channels to transport channels. The MAC layer can also implement error detection, error correction, or both to support retransmission and improve link efficiency. In the control plane, the RRC layer can provide the establishment, configuration, and maintenance of RRC connections between the UE 115 and network entity 105 or core network 130 supporting user plane data radio bearers. The PHY layer maps transport channels to physical channels.

[0079] UE 115 and network entity 105 can support data retransmission to increase the likelihood of successful data reception. Hybrid Automatic Repeat Request (HARQ) feedback is a technique used to increase the likelihood of correctly receiving data via communication links (e.g., communication link 125, D2D communication link 135). HARQ may include a combination of error detection (e.g., using Cyclic Redundancy Check (CRC)), forward error correction (FEC), and retransmission (e.g., Automatic Repeat Request (ARQ)). HARQ can improve throughput at the MAC layer under relatively poor radio conditions (e.g., low signal-to-noise ratio conditions). In some examples, the device may support same-slot HARQ feedback, in which case the device can provide HARQ feedback in a specific time slot for data received via a previous symbol in that time slot. In some other examples, the device may provide HARQ feedback in subsequent time slots or according to a different time interval.

[0080] Some wireless communication systems modulate signals used for transmission via a channel. For example, wireless devices may use QAM to modulate signals. Some modulation schemes use modulation constellations, where each point in the modulation constellation has a uniform probability for the modulation symbol. Probability shaping can utilize non-uniformly distributed modulation constellations to improve spectral efficiency. In some methods, MB distributions (e.g., This can increase (e.g., maximize) the source entropy for a given average power. Different methods can be used to perform probabilistic shaping, such as the CCDM method with an MB distribution. Probabilistic shaping can be performed to attempt to close the shaping gap (e.g., a 1.53 dB shaping gap) toward log(1+SNR) on an AWGN channel.

[0081] In some cases, radio fading can occur in MIMO channels, potentially leading to a loss of shaping gain from probabilistic shaping. For example, some methods for linear MIMO demodulation can be performed using linear approaches such as zero-forcing or linear MMSE techniques, which may not fully realize the shaping gain from probabilistic shaping. In some variations of linear MIMO demodulation, the inverse (or pseudo-inverse of a non-matrix) or regularized version of the channel (e.g., via linear MMSE) can first be applied to the corresponding (e.g., individual and distinct) MIMO layers of the received signal, and then SISO demodulation can be performed independently for each layer. Performing linear demodulation in this manner may waste the gain from probabilistic shaping and may exhibit some performance loss compared to linear demodulation of older QAM constellations. Therefore, a linear demodulation scheme that improves the performance of probabilistic shaping constellations is needed.

[0082] This document provides some examples of methods for linear MIMO demodulation using probabilistic shaping with auxiliary dimensions. A wireless device (e.g., UE 115 or network entity 105) may receive information indicating a non-uniform probability distribution of a modulation constellation used for a MIMO signal. The MIMO signal may be modulated using probabilistic shaping (e.g., a modulation constellation with a non-uniform probability distribution). One or more symbols of the MIMO signal may be transmitted or received via a channel. For example, a wireless device (e.g., UE 115 or network entity 105) may receive one or more symbols of a MIMO signal. The wireless device may demodulate a symbol based on a transformation of the modulation constellation to a subspace using a dimension associated with the non-uniform probability distribution and the point of the transformed modulation constellation closest to the projected symbol corresponding to the symbol in the subspace. In some aspects, the wireless device may add auxiliary dimensions to the modulation constellation to account for probabilistic shaping. For example, the modulation constellation may be transformed to a subspace using a dimension associated with the non-uniform probability distribution. The wireless device may project symbols into the subspace to generate projected symbols to determine the point of the transformed modulation constellation closest to the projected symbol in the subspace.

[0083] Considering non-uniform probability distributions with auxiliary dimensions can provide improved demodulation performance and spectral efficiency for modulation constellations with non-uniform probability distributions. For example, using an additional dimension during demodulation can achieve improved spectral efficiency while avoiding wasting the gain from probability shaping that would occur when performing SISO demodulation independently for each layer.

[0084] In some methods, different probability distributions can be used for different layers of the MIMO signal due to one or more SNR gaps between different MIMO layers; this can occur in a variety of scenarios. Some examples of demodulation methods using different distributions and modulation sizes for different MIMO layers are provided.

[0085] Figure 2 An example of a wireless communication system 200 supporting MIMO demodulation of a non-uniform modulation constellation according to one or more aspects of this disclosure is shown. The wireless communication system 200 may implement, or be implemented by, aspects of the wireless communication system 100. For example, the wireless communication system 200 includes a first wireless device 220, which may be related to… Figure 1 The described UE 115 or network entity 105, or another wireless device, is an example. The wireless communication system 200 also includes a second wireless device 225, which may be as described above. Figure 1 The example described is UE 115 or network entity 105, or another wireless device.

[0086] The first wireless device 220 can use communication link 230 to communicate with the second wireless device 225. In some examples, communication link 230 can be about Figure 1 An example of the described communication link 125. Communication link 230 may include a bidirectional link enabling uplink or downlink network communication. For example, a first wireless device 220 may use communication link 230 to send one or more transmissions 205, such as control signals or data signals, to a second wireless device 225, or the second wireless device 225 may use communication link 230 to send one or more transmissions 210, such as control signals or data signals, to the first wireless device 220.

[0087] The second wireless device 225 may transmit information 245 to the first wireless device 220 indicating a non-uniform probability distribution of the modulation constellation used for the MIMO signal. The first wireless device 220 may receive information 245. A modulation constellation may be a set of points representing symbols (e.g., modulation symbols). For example, a signal may be modulated to produce one or more symbols. These symbols may differ from each other in phase, amplitude, or frequency. A modulation constellation may include points that can be transmitted for each symbol. For example, each point of a modulation constellation may be expressed using an orthogonal dimension and an in-phase dimension. Examples of modulation constellations may include QAM (e.g., 8 QAM, 16 QAM, 32 QAM, 64 QAM, or 128 QAM, etc.) constellations, quadrature phase shift keying (QPSK) constellations, amplitude shift keying (ASK) constellations, or frequency shift keying (FSK) constellations, etc. In some modulation constellations, in a space having in-phase and orthogonal dimensions, some points may be closer to the origin than other points. For example, points relatively close to the origin can transmit using relatively less energy or power, while points relatively far from the origin can transmit using relatively more energy or power.

[0088] A non-uniform probability distribution of a modulation constellation can be a distribution of points within the constellation, where at least two points have different transmission probabilities. In some non-uniform probability distributions, points relatively close to the origin (or transmitting using lower energy or power) may transmit more frequently or have a greater transmission probability than points relatively far from the origin (or transmitting using higher energy or power), which may transmit less frequently or have a lower transmission probability. For example, some modulation constellations may utilize an MB distribution. , where Pr(x) represents the probability of transmitting point x (e.g., a 2N-dimensional modulation point with a transmission power or a distance from the origin), and v is a scaling factor. Therefore, the probability of a transmitting point decreases as the transmission power or distance from the origin increases.

[0089] In some examples, the information 245 indicating a non-uniform probability distribution may include one or more indices associated with the non-uniform probability distribution, one or more factors (e.g., one or more scaling factors) for determining the non-uniform probability distribution, one or more values ​​indicating the transmission probability of one or more points of a modulation constellation, or one or more other indications of the non-uniform probability distribution. For example, a second wireless device 225 (e.g., a network entity) may use downlink control information (DCI) or RRC messages to transmit information 245.

[0090] In some aspects, information 245 may indicate one or more non-uniform probability distributions relative to one or more modulation constellations having a uniform probability distribution. For example, information 245 indicating a non-uniform probability distribution may indicate one or more probability values ​​for one or more corresponding points of a modulation constellation. In some examples, information 245 may include an index indicating a non-uniform probability distribution associated with a modulation constellation.

[0091] In some respects, non-uniform probability distributions are included in the set of probability distributions. For example, the second wireless device 225, the first wireless device 220, or both may store a record of the set of probability distributions or associated modulation constellations. Information 245 may indicate a non-uniform probability distribution (or a modulation constellation with a non-uniform probability distribution) selected from the set of probability distributions. For example, the second wireless device 225 may transmit an indicator indicating the modulation and decoding scheme (MCS) of the selected non-uniform probability distribution (or modulation constellation with a non-uniform probability distribution).

[0092] The first wireless device 220 can receive one or more symbols 240 of a MIMO signal. The MIMO signal can be modulated using a non-uniform probability distribution. For example, the first wireless device 220 can receive one or more symbols 240 via multiple antennas of the first wireless device 220.

[0093] The first wireless device 220 can demodulate one or more symbols 240 of a MIMO signal. In some methods, the symbol 240 may be demodulated based on a modulation constellation-to-subspace transformation using a dimension associated with a non-uniform probability distribution, or the point of the transformed modulation constellation closest to the projected symbol (corresponding to symbol 240) in the subspace. In some examples, demodulating symbol 240 may include performing a modulation constellation transformation. Additionally or alternatively, demodulating symbol 240 may include determining (e.g., selecting) the point of the transformed modulation constellation closest to the projected symbol. In some methods, the transformation or determination of the point may be performed separately from demodulation. In some aspects, demodulation may include determining one or more bits corresponding to the point of the transformed modulation constellation closest to the projected symbol.

[0094] Demodulation of one or more symbols 240 may be based on the channel of the MIMO signal (e.g., channel estimation). In some methods, the first wireless device 220 may receive a signal (e.g., one or more reference signals) to generate a channel estimate. One or more symbols 240 of the MIMO signal may be received via the channel.

[0095] In some aspects, probabilistically shaped MIMO demodulation can be performed using an added auxiliary dimension (for the MB distribution). In one example, the first wireless device 220 can transform the modulation constellation to a subspace to demodulate one or more symbols 240. For example, probabilistically shaped MIMO demodulation can utilize a dimension associated with a non-uniform probability distribution (e.g., an added auxiliary dimension). In some methods, the number of dimensions associated with the non-uniform probability distribution can be associated with the number of layers of the MIMO signal (e.g., N). For a MIMO signal with N layers and an MB prior (e.g., ... The input-scaled MB distribution can be used to reduce the transformed 2N-dimensional lattice of MIMO constellation points in a multidimensional (e.g., 4N-dimensional) space using lattice basis reduction. Due to the maximum a posteriori (MAP) geometry of the MB distribution, transforming the modulation constellation may lead to channel matrix skew. (See reference...) Figure 4 An example of transforming a modulation constellation into a subspace is provided.

[0096] Transformation of the modulation constellation may include estimation of the channel (e.g., H) and transformation of the combination of modulation constellations. If {x} is a 2N-dimensional modulation point from the modulation constellation (e.g., from a QAM constellation) and H is the channel matrix, then, for example, Hx may represent a noise-free receiving point (e.g., a lattice point of the modulation constellation), and Hx+w may represent the modulation point received at the first wireless device (e.g., the receiver) after the influence of an additive noise vector (e.g., w).

[0097] In some respects, demodulating symbol 240 may include determining the AND points in 4N-dimensional real space (or 2N-dimensional complex space). The nearest grid point For example, in the case of the geometric effects of probabilistic MAP decoding, demodulating symbol 240 may include determining the points in the 4N-dimensional real space (or 2N-dimensional complex space). The nearest grid point , where y represents the received symbol 240. In some examples, the coefficients... a (exist ax The value (in the middle) can depend on one or more parameters of the MB distribution and the noise power (or the channel's signal-to-noise ratio (SNR)). In some examples, the coefficients... a (exist ax The fading channel (C) may depend on one or more other parameters of the signal transmission or channel (e.g., statistics of the fading channel).

[0098] In some aspects, demodulating symbol 240 of the MIMO signal may include projecting the symbol into a subspace to generate projected symbols, thereby determining the point of the transformed modulation constellation closest to the projected symbols. In some examples, a linear solution may involve converting the received signal... Projected to The subspace it spans, where I denotes the identity matrix. In some examples, projection can be performed to obtain points. Where P represents the projection matrix ,in This indicates the conjugate transpose.

[0099] In some respects, the first wireless device 220 can be based on Point x is determined by the following: Application The pseudo-inverse (or Moore-Penrose inverse), where ,and .quantity It can be a non-discrete linear estimate of the transmitted symbol vector x. The described formula can also be applied to N MIMO layers in N-dimensional complex space (with N additional auxiliary dimensions for MIMO demodulation with probabilistic shaping).

[0100] Some examples of the techniques described in this article can be utilized. Instead To perform demodulation (e.g., in addition to projections into subspaces within a larger space). Utilizing One type of regularization can be provided to help reduce the orthogonality defect of H. In some methods, regularization (e.g., linear minimum mean square error (MMSE) instead of zero-forcing) can be applied to introduce a certain bias to reduce the effective variance of the noise (e.g., reduce the variance of the estimate). This paper applies regularization to provide an improved MAP estimate (instead of maximum likelihood). Another enhancement to regularization can also be provided (e.g., reducing the orthogonality defect and reducing the effective variance of the noise). The amount of regularization can be chosen based on the prior distribution of the constellation (e.g., to achieve MAP rather than maximum likelihood (ML) estimation). As described in this paper, regularization can be applied to produce reduced variance in the estimate as a trade-off with the added bias introduced.

[0101] In some examples, the first wireless device 220 can perform non-discrete estimation (e.g., x) of symbol vectors comprising multiple symbol layers. Decoding is performed to determine the point of the transformed modulation constellation closest to the projected symbol. For example, in determining a non-discrete linear estimate (e.g., Afterward, this non-discrete linear estimate can be used for hard or soft decoding of each layer of the data symbols. In some methods, one or more SISO techniques can be used to determine the nearest point in the corresponding complex plane for hard decoding or detection of uncoded symbols.

[0102] Additionally or alternatively, one or more modified SISO techniques can be used to calculate the log-likelihood ratio (LLR) (or other soft decoding metrics can be obtained separately for each layer). For the LLR calculation of each layer, the LLR is calculated at the constellation point on the j-th layer. The distance metric can be given by the following: ,in yes arrive The distance across the subspaces traversed. In some examples, for some (e.g., all) layers and some (e.g., all) constellation points, They can be the same. For example, It may depend on the received signal vector (e.g., it may depend only on the received signal vector).

[0103] In some respects, the first wireless device 220 may utilize different probability distributions of at least two layers (e.g., spatial layers) to demodulate one or more symbols 240. For example, the first wireless device 220 may perform MIMO demodulation with probability shaping of each layer having a different rate or modulation distribution.

[0104] In some examples, a first non-uniform probability distribution may be associated with a first layer of the MIMO signal. A first wireless device 220 may receive a second symbol 240 of a second layer of the MIMO signal, wherein the second layer of the MIMO signal is modulated with a second non-uniform probability distribution different from the first non-uniform probability distribution associated with the first layer. The first wireless device 220 may demodulate the second symbol of the second layer of the MIMO signal based on a transformation (e.g., a second transformation) of the modulation constellation in a second subspace using a dimension associated with the second non-uniform probability distribution, and a second point in the second subspace closest to the second symbol of the transformed modulation constellation (e.g., transformed using the second transformation).

[0105] In some examples, the first wireless device 220 may receive an indication of a second non-uniform probability distribution associated with the second layer of the MIMO signal. For example, information 245 may provide an indication of the second non-uniform probability distribution.

[0106] In some methods, MIMO demodulation with probability shaping of each layer having a different rate or modulation distribution can be applied. For example, coefficient vectors corresponding to the BM distributions of the N MIMO layers can be used. (in and These correspond to, for example, the correlation coefficients of the k-th MIMO layer. Each coefficient can be associated with the geometric interpretation of MAP decoding.

[0107] The first wireless device 220 can project the received 4N-dimensional points onto the probabilistic shaping and demodulation equivalent receiving constellation points. The 2N-dimensional subspace traversed to obtain , where T denotes matrix transpose. In some methods, the first wireless device can perform operations similar to those described herein (which can be used for the same probability distribution at each layer), only... and Due to the potential SNR gap between different MIMO layers, each layer can enhance its demodulation performance by utilizing different non-uniform distributions.

[0108] In some examples, the first wireless device 220 may send capability signaling to the second wireless device 225, indicating the capability of the first wireless device 220 to receive or demodulate one or more symbols 240 of a MIMO signal modulated with one or more non-uniform probability distributions. For example, the capability signaling may indicate that the first wireless device 220 can demodulate the symbol 240 based on one or more non-uniform probability distributions.

[0109] In some examples, the second wireless device 225 may send one or more configuration signaling messages to the first wireless device 220, which are used to configure the first wireless device 220 to receive or demodulate one or more symbols 240 of a MIMO signal modulated with one or more non-uniform probability distributions. For example, the configuration signaling may instruct the first wireless device 220 to demodulate the symbol 240 based on one or more non-uniform probability distributions. In some examples, the configuration signaling may be transmitted in response to receiving capability signaling.

[0110] In some examples, one or more symbols 240 demodulated by the first wireless device 220 may indicate data or control information. In some examples, the first wireless device 220 may perform one or more operations on the demodulated symbols. For example, the first wireless device 220 may perform decoding or deformatting to obtain data or control information.

[0111] Figure 3 Figure 300 illustrates an example of demodulation of a modulation constellation supporting one or more aspects of this disclosure. Specifically, Figure 3 A first example of demodulation 305 using uniform QAM for SISO, a second example of demodulation 340 using probabilistic integer constellation for SISO, and a third example of demodulation 365 using probabilistic integer constellation with MB prior for SISO are illustrated.

[0112] In the first example, a QAM constellation with uniform probabilities is utilized, where points in the QAM constellation have the same transmission probability. For example, a first received signal 315 (e.g., y) can be received, and a first distance 310 from the first received signal 315 to a constellation point can be determined to select the constellation point closest to the first received signal 315. In the first example, the first received signal 315 is depicted after equalization. The first distance 310 can be expressed as a distance metric. .

[0113] To demodulate uniform QAM (in Gaussian noise), the log-likelihood... It can be equivalent to a distance metric: In this case, the maximum likelihood can be expressed as Log-maximal a posteriori (LOG-MAP) can be expressed as: The maximum log-map can be expressed as: In the second example, a probabilistically shaped QAM constellation is used, where points in the QAM constellation have different transmission probabilities. For example, a second received signal 335 (e.g., y) can be received, and a second distance 330 from the second received signal 335 to a constellation point can be determined to select the constellation point closest to the second received signal 335. In the second example, the second received signal 335 is depicted after equalization. The second distance 330 can be expressed as... The basic distance 320 can be expressed as... The probabilistic distance of 325 can be expressed as... .

[0114] For probabilistic integer QAM constellations, the log-likelihood function may include a symbolic prior: The distance metric can be expressed as: In this case, maximum likelihood, log-map, and maximum log-map are calculated using a distance metric. This can be generalized to probabilistic integer cases.

[0115] In the third example, a probabilistically shaped QAM constellation is utilized together with an MB prior for SISO. In some of the methods described herein, input scaling can be performed on the channel (H) and the received symbols 350 (y), and demodulation (e.g., QAM demodulation) can be utilized based on the input scaling.

[0116] For a modulation constellation with uniform transmission probability across symbols in the SISO case, the channel effect is applied to the constellation points on axis 370 as shown in the third example. In the case of non-uniform probability, the wireless device can apply input scaling, which, in the SISO case, has the effect of rotating the points along line 375. The amount of rotation along line 375 can be related to the distance 360 ​​(e.g., Related to this. To determine the nearest constellation point to the received symbol 350 (y), the wireless device can project symbol 350 345 onto line 375 to determine the projected symbol 355. The nearest constellation point to the projected symbol 355 can be determined along line 375. For example, for MB prior ( Distance calculations or operations can be performed based on the third example of demodulation 365. In some methods, distance calculations or operations can be performed on multiple layers (e.g., signal layer or interference layer).

[0117] Some of the methods described in this paper utilize a transformation of the modulation constellation used for MIMO with an additional dimension, where the modulation constellation is transformed to a subspace based on probabilistic shaping. The received symbols can be projected onto the subspace to generate projected symbols to determine the nearest constellation point in the subspace.

[0118] Figure 4 Figure 400 illustrates an example of demodulation supporting a non-uniform modulation constellation MIMO demodulation according to one or more aspects of this disclosure. Specifically, Figure 4 An example of a modulation constellation 425 is illustrated, where the points of the modulation constellation 425 are depicted with solid circles. At a wireless device (e.g., a receiver), the modulation constellation 425 may be included in a first subspace 405 (depicted with solid lines). The first subspace 405 may be a 2N-dimensional subspace of a 4N-dimensional space, which includes a grid of received constellation points after the influence of a channel (e.g., a channel matrix or H).

[0119] To perform demodulation in some methods, a wireless device may generate an estimate of the channel (e.g., H). The wireless device may apply the channel estimate (and, for example, an additive noise vector w) to a default constellation to generate a modulation constellation 425 (e.g., H). ).

[0120] The wireless device can use a dimension associated with a non-uniform probability distribution to transform the modulation constellation 425 to a second subspace 410 (depicted with dashed lines). In some examples, the second subspace 410 may include a dimension number twice the number of layers of the MIMO signal and may be associated with a space four times the number of layers of the MIMO signal. For example, the wireless device can transform the modulation constellation 425 to the second subspace 410, which may be a 2N-dimensional subspace of a 4N-dimensional space, comprising a lattice of constellation points 430 (depicted with hollow circles) after the channel matrix and the effects of input scaling due to the MB prior distribution. The lattice of constellation points 430 can be expressed as... For reference Figure 2 As described. The transformation can be related to distance 420 (e.g., MB prior). (Distance calculation).

[0121] The received symbol 435 may be included in subspace 405. For example, the received symbol 435 may be expressed as ,in It can be calculated based on symbols (e.g., received symbols y before considering the channel), channel estimation, and additive noise w.

[0122] The wireless device can project the received symbol 435 415 into the second subspace 410. For example, the wireless device can project the received symbol 435 (e.g., Projected to The subspace traversed is used to obtain the projection symbol 440. In some examples, projection can be performed to obtain points. Where P represents the projection matrix ,in Indicates conjugate transpose (e.g., For reference Figure 2 (As described).

[0123] In some examples, the wireless device can determine the point 445 of the modulation constellation closest to the projected symbol 440 in order to demodulate the received symbol. For example, the wireless device can be based on... The nearest point 445 (e.g., x) is determined by the following: [Application] The pseudo-inverse (or Moore-Penrose inverse), where ,and .quantity It can be a non-discrete linear estimate of the transmitted symbol vector x, and the coefficients aThis can be based on one or more parameters of a probabilistic shaping (e.g., MB) distribution, noise power (e.g., the channel's SNR), or one or more other parameters of signal transmission or the channel (e.g., statistics of a fading channel). Additionally or alternatively, the wireless device may determine the distance (e.g., Euclidean distance) between each cell in the grid of the projected symbol 440 and constellation point 430. The wireless device may determine (e.g., select) the nearest point 445 (e.g., the point with the smallest distance to the projected symbol 440).

[0124] The nearest point 445 can be a determined point used for demodulation. For example, a wireless device can determine (e.g., generate or extract) one or more bits associated with (e.g., mapped to) the nearest point 445.

[0125] Figure 5 An example of a process flow 500 supporting MIMO demodulation of a non-uniform modulation constellation according to one or more aspects of this disclosure is shown. The wireless communication system may include a first wireless device 220-a and a second wireless device 225-a. The first wireless device 220-a may be an example of a first wireless device 220 (e.g., UE 115 or network entity 105), and the second wireless device 225-a may be an example of a second wireless device 225 (e.g., network entity 105 or UE 115), as described herein.

[0126] In the following description of process flow 500, operations between the second wireless device 225-a and the first wireless device 220-a may be transmitted in a different order than the example order shown, or operations performed by the second wireless device 225-a and the first wireless device 220-a may be performed in a different order or at different times. Some operations may also be omitted from process flow 500, or other operations may be added to process flow 500. Furthermore, although some operations or signaling are shown to occur at different times for discussion purposes, these operations may actually occur simultaneously or in some examples in overlapping time periods.

[0127] At point 505, the second wireless device 225-a can transmit (e.g., output) a signal (e.g., a reference signal, a probe signal, etc.). For example, the first wireless device 220-a can receive (e.g., acquire) a signal, such as a reference signal. Figure 2 As described.

[0128] At 510, the first wireless device 220-a can estimate the channel based on the signal. For example, the first wireless device 220-a can store a template signal having one or more target characteristics (e.g., frequency, amplitude, or phase). The first wireless device 220-a can estimate the channel (e.g., H) based on calculations performed using the signal and the template signal indicating the effect of the channel on the signal.

[0129] At 515, the second wireless device 225-a can output information indicating a non-uniform probability distribution. For example, this information can use one or more explicit indicators (e.g., indexes, values) or implicit indicators (e.g., timing, or formatting) to indicate the non-uniform probability distribution of the modulation constellation. The first wireless device 220-a can receive information, such as reference... Figure 2 As described.

[0130] At position 520, the second wireless device 225-a can output a MIMO signal. The MIMO signal can be modulated according to a non-uniform probability distribution. For example, the MIMO signal can be modulated based on an MB distribution. The first wireless device 220-a can receive the MIMO signal, as shown in the reference. Figure 2 As described.

[0131] At position 525, the first wireless device 220-a can demodulate one or more symbols of the MIMO signal. For example, the first wireless device 220-a can use a dimension associated with a non-uniform probability distribution to transform the modulation constellation into a subspace. The first wireless device 220-a can project the received symbols of the MIMO signal into the subspace. The first wireless device 220-a can determine the point of the transformed modulation constellation closest to the projected symbol. In some examples, the first wireless device 220-a can perform hardware decoding or software decoding. In some methods, the first wireless device 220-a can employ about Figure 1 , Figure 2 , Figure 3 or Figure 4 The described one or more aspects are used to demodulate one or more symbols of a MIMO signal.

[0132] Figure 6 A block diagram 600 of a device 605 supporting MIMO demodulation of a non-uniform modulation constellation according to one or more aspects of this disclosure is shown. Device 605 may be an example of various aspects of a wireless device as described herein. Device 605 may include a receiver 610, a transmitter 615, and a communication manager 620. Device 605, or one or more components of device 605 (e.g., receiver 610, transmitter 615, communication manager 620), may include at least one processor that may be coupled to at least one memory to individually or jointly support or implement the described techniques. Each of these components may communicate with each other (e.g., via one or more buses).

[0133] Receiver 610 may provide components for receiving information (such as packets, user data, control information, or any combination thereof) associated with various information channels (e.g., control channels, data channels, information channels associated with MIMO demodulation of a non-uniform modulation constellation). The information may be passed to other components of device 605. Receiver 610 may utilize a single antenna or a collection of antennas.

[0134] Transmitter 615 may provide components for transmitting signals generated by other components of device 605. For example, transmitter 615 may transmit information (such as packets, user data, control information, or any combination thereof) associated with various information channels (e.g., control channels, data channels, information channels associated with MIMO demodulation of a non-uniform modulation constellation). In some examples, transmitter 615 may be co-located with receiver 610 in a transceiver module. Transmitter 615 may utilize a single antenna or a collection of multiple antennas.

[0135] The communication manager 620, receiver 610, transmitter 615, or various combinations or components thereof may be examples of components used to perform various aspects of MIMO demodulation of a non-uniform modulation constellation as described herein. For example, the communication manager 620, receiver 610, transmitter 615, or various combinations or components thereof may be able to perform one or more of the functions described herein.

[0136] In some examples, the communication manager 620, receiver 610, transmitter 615, or various combinations or components thereof may be implemented in hardware (e.g., in communication management circuitry). The hardware may include at least one of a processor, DSP, CPU, ASIC, FPGA, or other programmable logic device, microcontroller, discrete gate or transistor logic unit, discrete hardware component, or any combination thereof, configured as or otherwise individually or collectively to support components for performing the functions described herein. In some examples, at least one processor and at least one memory coupled to said at least one processor may be configured to perform one or more of the functions described herein (e.g., instructions stored in at least one memory are executed individually or collectively by one or more processors).

[0137] Additionally or alternatively, the communication manager 620, receiver 610, transmitter 615, or various combinations or components thereof may be implemented in code (e.g., as communication management software or firmware) executed by at least one processor (e.g., referred to as processor executable code). If implemented in code executed by at least one processor, the functionality of the communication manager 620, receiver 610, transmitter 615, or various combinations or components thereof may be performed by a general-purpose processor, DSP, CPU, ASIC, FPGA, microcontroller, or any combination of these or other programmable logic devices (e.g., configured as or otherwise individually or jointly to support components for performing the functions described in this disclosure).

[0138] In some examples, the communication manager 620 may be configured to use a receiver 610, a transmitter 615, or both, or otherwise cooperate with the receiver, transmitter, or both to perform various operations (e.g., receiving, acquiring, monitoring, outputting, transmitting). For example, the communication manager 620 may receive information from the receiver 610, transmit information to the transmitter 615, or integrate with the receiver 610, transmitter 615, or a combination of both to acquire information, output information, or perform various other operations as described herein.

[0139] For example, the communication manager 620 can, is configured, or is operable to support components for receiving information indicating a non-uniform probability distribution of a modulation constellation used for a MIMO signal. The communication manager 620 can, is configured, or is operable to support components for receiving symbols of a MIMO signal modulated with a non-uniform probability distribution. The communication manager 620 can, is configured, or is operable to support components for demodulating a symbol based on a transformation of the modulation constellation to a subspace using a dimension associated with the non-uniform probability distribution and the point of closest projection of the transformed modulation constellation to the corresponding symbol in the subspace.

[0140] By including or configuring a communication manager 620 according to an example as described herein, device 605 (e.g., controlling receiver 610, transmitter 615, communication manager 620 or a combination thereof or at least one processor otherwise coupled to them) can support techniques for reducing power consumption or utilizing communication resources more efficiently.

[0141] Figure 7A block diagram 700 of a device 705 supporting MIMO demodulation of a non-uniform modulation constellation according to one or more aspects of this disclosure is shown. Device 705 may be an example of aspects of a device 605 as described herein or a wireless device (e.g., UE 115 or network entity 105). Device 705 may include a receiver 710, a transmitter 715, and a communication manager 720. Device 705, or one or more components of device 705 (e.g., receiver 710, transmitter 715, communication manager 720), may include at least one processor that may be coupled to at least one memory to support the described techniques. Each of these components may communicate with each other (e.g., via one or more buses).

[0142] Receiver 710 may provide components for receiving information (such as packets, user data, control information, or any combination thereof) associated with various information channels (e.g., control channels, data channels, information channels associated with MIMO demodulation of a non-uniform modulation constellation). The information may be passed to other components of device 705. Receiver 710 may utilize a single antenna or a collection of antennas.

[0143] Transmitter 715 may provide components for transmitting signals generated by other components of device 705. For example, transmitter 715 may transmit information (such as packets, user data, control information, or any combination thereof) associated with various information channels (e.g., control channels, data channels, information channels associated with MIMO demodulation of a non-uniform modulation constellation). In some examples, transmitter 715 may be co-located with receiver 710 in a transceiver module. Transmitter 715 may utilize a single antenna or a collection of multiple antennas.

[0144] Device 705 or its various components may be examples of various aspects of MIMO demodulation for performing non-uniform modulation constellations as described herein. For example, communication manager 720 may include distribution component 725, MIMO signal component 730, demodulation component 735, or any combination thereof. Communication manager 720 may be examples of aspects of communication manager 620 as described herein. In some examples, communication manager 720 or its various components may be configured to use receiver 710, transmitter 715, or both, or otherwise cooperate with such receiver, transmitter, or both to perform various operations (e.g., receiving, acquiring, monitoring, outputting, transmitting). For example, communication manager 720 may receive information from receiver 710, transmit information to transmitter 715, or be integrated with receiver 710, transmitter 715, or a combination thereof to acquire information, output information, or perform various other operations as described herein.

[0145] Distribution component 725 is capable of, configured to, or operable to support components for receiving information indicating a non-uniform probability distribution of the modulation constellation used for a MIMO signal. MIMO signal component 730 is capable of, configured to, or operable to support components for receiving symbols of a MIMO signal modulated with a non-uniform probability distribution. Demodulation component 735 is capable of, configured to, or operable to support components for demodulating a symbol based on a transformation of the modulation constellation to a subspace using a dimension associated with the non-uniform probability distribution and the point of closest projection of the transformed modulation constellation to the corresponding symbol in the subspace.

[0146] Figure 8 A block diagram 800 of a communication manager 820 supporting MIMO demodulation of a non-uniform modulation constellation according to one or more aspects of this disclosure is shown. The communication manager 820 may be an example of aspects of the communication manager 620, communication manager 720, or both as described herein. The communication manager 820 or its various components may be examples of components for performing various aspects of MIMO demodulation of a non-uniform modulation constellation as described herein. For example, the communication manager 820 may include a distribution component 825, a MIMO signal component 830, a demodulation component 835, a channel estimation component 840, a decoding component 845, or any combination thereof. Each of these components, or its components or sub-components (e.g., one or more processors, one or more memories), may communicate directly or indirectly with each other (e.g., via one or more buses).

[0147] Distribution component 825 is capable of, configured to, or operable to support components for receiving information indicating a non-uniform probability distribution of the modulation constellation used for a MIMO signal. MIMO signal component 830 is capable of, configured to, or operable to support components for receiving symbols of a MIMO signal modulated with a non-uniform probability distribution. Demodulation component 835 is capable of, configured to, or operable to support components for demodulating a symbol based on a transformation of the modulation constellation to a subspace using a dimension associated with the non-uniform probability distribution and the point of closest projection of the transformed modulation constellation to the corresponding symbol in the subspace.

[0148] In some examples, demodulating a symbol involves projecting the symbol into a subspace to generate a projected symbol, in order to determine the point in the transformed modulation constellation closest to the projected symbol.

[0149] In some examples, the channel estimation component 840 is capable of, configured to, or able to operate to support components for receiving signals to generate a channel estimate, the symbol being received via the channel, wherein the transformation of the modulation constellation includes a transformation of the channel estimate and the combination of the modulation constellation.

[0150] In some examples, the number of dimensions associated with a non-uniform probability distribution is related to the number of layers in the MIMO signal.

[0151] In some examples, the subspace includes a number of dimensions that is twice the number of layers in a MIMO signal, and is associated with a space that is four times the number of layers in a MIMO signal.

[0152] In some examples, the decoding component 845 is capable of, configured to, or operable to support decoding of non-discrete estimates of symbol vectors for a set of symbols comprising multiple symbol layers to determine the point closest to the projected symbol in the transformed modulation constellation.

[0153] In some examples, a non-uniform probability distribution is associated with a first layer of the MIMO signal, and the MIMO signal component 830 is capable of, configured to, or operable to support components for receiving a second symbol of a second layer of the MIMO signal modulated with a second non-uniform probability distribution different from the non-uniform probability distribution associated with the first layer. In some examples, a non-uniform probability distribution is associated with a first layer of the MIMO signal, and the demodulation component 835 is capable of, configured to, or operable to support components for demodulating a second symbol of the second layer of the MIMO signal based on a transformation (e.g., a second transformation) of the modulation constellation in a second subspace using a dimension associated with the second non-uniform probability distribution, and a second point in the second subspace closest to the second symbol of the transformed modulation constellation (e.g., transformed with the second transformation).

[0154] In some examples, the distribution component 825 is capable of, configured to, or able to operate to support components for receiving an indication of a second non-uniform probability distribution associated with a second layer of the MIMO signal.

[0155] In some examples, the modulation constellation is a QAM constellation.

[0156] Figure 9A diagram of a system 900 including a device 905 supporting MIMO demodulation of a non-uniform modulation constellation, according to one or more aspects of this disclosure, is shown. Device 905 may be an example of device 605, device 705, or a wireless device as described herein, or may include components thereof. Device 905 may include components for bidirectional voice and data communication, including components for transmitting and receiving communications, such as a communication manager 920, an I / O controller (such as I / O controller 910), a transceiver 915, one or more antennas 925, at least one memory 930, code 935, and at least one processor 940. These components may communicate electronically or be otherwise coupled (e.g., operatively, communicatively, functionally, electronically, or electrically) via one or more buses (e.g., bus 945).

[0157] I / O controller 910 manages the input and output signals of device 905. I / O controller 910 can also manage peripheral devices not integrated into device 905. In some cases, I / O controller 910 may represent a physical connection or port to an external peripheral device. In some cases, I / O controller 910 may utilize an operating system such as iOS. ® ANDROID ® MS-DOS ® MS-WINDOWS ® OS / 2 ® UNIX ® LINUX ® Alternatively, it may be another known operating system. Additionally or alternatively, the I / O controller 910 may represent, or interact with, a modem, keyboard, mouse, touchscreen, or similar device. In some cases, the I / O controller 910 may be implemented as part of one or more processors, such as at least one processor 940. In some cases, a user may interact with the device 905 via the I / O controller 910 or via hardware components controlled by the I / O controller 910.

[0158] In some cases, device 905 may include a single antenna. However, in other cases, device 905 may have more than one antenna, which can concurrently transmit or receive multiple wireless transmissions. Transceiver 915 can communicate bidirectionally via one or more antennas 925 using a wired or wireless link as described herein. For example, transceiver 915 may represent a wireless transceiver and can communicate bidirectionally with another wireless transceiver. Transceiver 915 may also include a modem for: modulating packets; providing the modulated packets to one or more antennas 925 for transmission; and demodulating packets received from one or more antennas 925. Transceiver 915, or transceiver 915 and one or more antennas 925, may be an example of transmitter 615, transmitter 715, receiver 610, receiver 710, or any combination thereof or components thereof as described herein.

[0159] At least one memory 930 may include RAM and ROM. At least one memory 930 may store computer-readable code, computer-executable code, or processor-executable code, such as code 935. Code 935 may include instructions that, when executed by at least one processor 940, cause device 905 to perform the various functions described herein. Code 935 may be stored in a non-transitory computer-readable medium such as system memory or another type of memory. In some cases, code 935 may not be directly executable by at least one processor 940, but may enable a computer (e.g., when compiled and executed) to perform the functions described herein. In some cases, at least one memory 930 may include a BIOS, etc., which controls basic hardware or software operations, such as interaction with peripheral components or devices.

[0160] At least one processor 940 may include one or more intelligent hardware devices (e.g., one or more general-purpose processors, one or more DSPs, one or more central processing units (CPUs), one or more graphics processing units (GPUs), one or more neural processing units (NPUs) (also known as neural network processors or deep learning processors (DLPs)), one or more microcontrollers, one or more ASICs, one or more FPGAs, one or more programmable logic devices, discrete gate or transistor logic, one or more discrete hardware components, or any combination thereof). In some cases, at least one processor 940 may be configured to use a memory controller to operate a memory array. In some other cases, the memory controller may be integrated into at least one processor 940. At least one processor 940 may be configured to execute computer-readable instructions stored in memory (e.g., at least one memory 930) to cause device 905 to perform various functions (e.g., functions or tasks supporting MIMO demodulation of non-uniform modulation constellations). For example, device 905 or components of device 905 may include at least one processor 940 and at least one memory 930 coupled to or coupled to at least one processor 940, wherein at least one processor 940 and at least one memory 930 are configured to perform the various functions described herein. In some examples, at least one processor 940 may include multiple processors, and at least one memory 930 may include multiple memories. One or more of the multiple processors may be coupled to one or more of the multiple memories, which may be configured individually or collectively to perform the various functions described herein. In some examples, at least one processor 940 may be a component of a processing system, which may refer to a system of machines (such as a series of machines), circuits (including, for example, one or both of processor circuitry (which may include at least one processor 940) and memory circuitry (which may include at least one memory 930)) or components that receive or receive input and process the input to produce, generate, or obtain output. The processing system may be configured to perform one or more of the functions described herein. For example, at least one processor 940 or a processing system including at least one processor 940 may be configured, capable of being configured, or operable to cause device 905 to perform one or more of the functions described herein. Furthermore, as described herein, “configured to,” “capable of being configured to,” and “capable of operating to” are used interchangeably and can be associated with the ability to perform one or more of the functions described herein when executing code 935 (e.g., processor-executable code) stored in at least one memory 930 or otherwise executing the code.

[0161] For example, the communication manager 920 can, is configured, or is operable to support components for receiving information indicating a non-uniform probability distribution of a modulation constellation used for a MIMO signal. The communication manager 920 can, is configured, or is operable to support components for receiving symbols of a MIMO signal modulated with a non-uniform probability distribution. The communication manager 920 can, is configured, or is operable to support components for demodulating a symbol based on a transformation of the modulation constellation to a subspace using a dimension associated with the non-uniform probability distribution and the point of the transformed modulation constellation closest to the projected symbol corresponding to the symbol in the subspace.

[0162] By including or configuring a communication manager 920 according to an example as described herein, device 905 can support techniques for improving communication reliability, reducing latency, utilizing communication resources more efficiently, improving coordination between devices, extending battery life, or improving the utilization of processing power.

[0163] In some examples, the communication manager 920 may be configured to perform various operations (e.g., receiving, monitoring, transmitting) using a transceiver 915, one or more antennas 925, or any combination thereof, or otherwise cooperating with such transceiver, one or more antennas, or any combination thereof. Although the communication manager 920 is illustrated as a separate component, in some examples, one or more functions described with reference to the communication manager 920 may be supported or performed by at least one processor 940, at least one memory 930, code 935, or any combination thereof. For example, code 935 may include instructions that can be executed by at least one processor 940 to cause device 905 to perform various aspects of MIMO demodulation of a non-uniform modulation constellation as described herein, or at least one processor 940 and at least one memory 930 may be otherwise configured to perform or support such operations individually or jointly.

[0164] Figure 10 A flowchart illustrating a method 1000 for MIMO demodulation supporting a non-uniform modulation constellation according to one or more aspects of this disclosure is shown. Operation of method 1000 may be implemented by a wireless device or its components as described herein. For example, operation of method 1000 may be implemented by, as referenced... Figures 1 to 9 The wireless device described performs the functions described. In some examples, the wireless device may execute a set of instructions to control the functional elements of the wireless device to perform the described functions. Additionally or alternatively, the wireless device may use dedicated hardware to perform aspects of the described functions.

[0165] At 1005, the method may include: receiving information indicating a non-uniform probability distribution of a modulation constellation for a MIMO signal. The operation of 1005 may be performed according to examples as disclosed herein. In some examples, aspects of the operation of 1005 may be derived from references... Figure 8 The described distribution component 825 is used to execute this.

[0166] At 1010, the method may include: receiving symbols of a MIMO signal modulated with a non-uniform probability distribution. The operation of 1010 may be performed according to the examples disclosed herein. In some examples, aspects of the operation of 1010 may be derived from references... Figure 8 The MIMO signal component 830 is used to perform this.

[0167] At 1015, the method may include: demodulating the symbol based on a transformation of the modulation constellation to a subspace using a dimension associated with a non-uniform probability distribution and the point of the transformed modulation constellation closest to the corresponding projected symbol in the subspace. The operation at 1015 may be performed according to examples as disclosed herein. In some examples, aspects of the operation at 1015 may be derived from references... Figure 8 The demodulation component 835 described is used to perform this.

[0168] Figure 11 A flowchart illustrating a method 1100 for MIMO demodulation of a non-uniform modulation constellation according to one or more aspects of this disclosure is shown. Operation of method 1100 may be implemented by a wireless device or its components as described herein. For example, operation of method 1100 may be implemented by, as referenced... Figures 1 to 9 The wireless device described performs the functions described. In some examples, the wireless device may execute a set of instructions to control the functional elements of the wireless device to perform the described functions. Additionally or alternatively, the wireless device may use dedicated hardware to perform aspects of the described functions.

[0169] At 1105, the method may include: receiving a signal to generate a channel estimate. The operation of 1105 may be performed according to examples as disclosed herein. In some examples, aspects of the operation of 1105 may be derived from references... Figure 8 The described channel estimation component 840 is used to perform this.

[0170] At 1110, the method may include: receiving information indicating a non-uniform probability distribution of a modulation constellation for a MIMO signal. The operation of 1110 may be performed according to examples as disclosed herein. In some examples, aspects of the operation of 1110 may be derived from references... Figure 8 The described distribution component 825 is used to execute this.

[0171] At 1115, the method may include: receiving symbols of a MIMO signal modulated with a non-uniform probability distribution, and the symbols being received via a channel. The operation of 1115 may be performed according to the examples disclosed herein. In some examples, aspects of the operation of 1115 may be derived from references... Figure 8 The MIMO signal component 830 is used to perform this.

[0172] At 1120, the method may include: demodulating the symbol based on a transformation of the modulation constellation to a subspace using a dimension associated with a non-uniform probability distribution and the point closest to the projected symbol corresponding to the symbol in the subspace of the transformed modulation constellation, wherein the transformation of the modulation constellation includes channel estimation and a transformation of the combination of modulation constellations. The operation of 1120 may be performed according to examples as disclosed herein. In some examples, aspects of the operation of 1120 may be derived from references... Figure 8 The demodulation component 835 described is used to perform this.

[0173] The following provides an overview of the various aspects of this disclosure.

[0174] Aspect 1: A method for wireless communication by a wireless device, the method comprising: receiving information indicating a non-uniform probability distribution for a modulation constellation of a MIMO signal; receiving symbols of the MIMO signal modulated with the non-uniform probability distribution; and demodulating the symbols at least in part based on a transformation of the modulation constellation to a subspace using a dimension associated with the non-uniform probability distribution and the point of the transformed modulation constellation closest to a projected symbol in the subspace corresponding to the symbol.

[0175] Aspect 2: According to the method of aspect 1, demodulating the symbol includes: projecting the symbol into the subspace to generate the projected symbol, thereby determining the point of the transform modulation constellation closest to the projected symbol.

[0176] Aspect 3: The method according to any one of Aspects 1 to 2, the method further comprising: receiving a signal to generate an estimate of a channel, the symbol being received via the channel, wherein the transformation of the modulation constellation includes a transformation of the combination of the estimate of the channel and the modulation constellation.

[0177] Aspect 4: The method according to any one of Aspects 1 to 3, wherein the number of the dimensions associated with the non-uniform probability distribution is associated with the number of layers of the MIMO signal.

[0178] Aspect 5: According to the method of aspect 4, the subspace includes a number of dimensions twice the number of layers of the MIMO signal and is associated with a space four times the number of layers of the MIMO signal.

[0179] Aspect 6: The method according to any one of Aspects 1 to 5, the method further comprising: decoding a non-discrete estimate of the symbol vector of the symbol comprising a plurality of symbol layers to determine the point of the transformed modulation constellation closest to the projected symbol.

[0180] Aspect 7: The method according to any one of Aspects 1 to 6, wherein the non-uniform probability distribution is associated with a first layer of the MIMO signal, the method further comprising: receiving a second symbol of a second layer of the MIMO signal, the second layer of the MIMO signal being modulated with a second non-uniform probability distribution different from the non-uniform probability distribution associated with the first layer; and demodulating the second symbol of the second layer of the MIMO signal at least in part based on a second transformation of the modulation constellation in a second subspace using a dimension associated with the second non-uniform probability distribution and a second point of the transformed modulation constellation closest to the second symbol in the second subspace.

[0181] Aspect 8: The method according to aspect 7, the method further comprising: receiving an indication of a second non-uniform probability distribution associated with the second layer of the MIMO signal.

[0182] Aspect 9: The method according to any one of Aspects 1 to 8, wherein the modulation constellation is a QAM constellation.

[0183] Aspect 10: A wireless device comprising: one or more memories storing processor-executable code; and one or more processors coupled to the one or more memories and capable of operating individually or jointly to execute the code to cause the wireless device to perform a method according to any one of Aspects 1 to 9.

[0184] Aspect 11: A wireless device comprising at least one component for performing the method according to any one of aspects 1 to 9.

[0185] Aspect 12: A non-transitory computer-readable medium storing code, said code comprising instructions executable by one or more processors to perform the method according to any one of aspects 1 to 9.

[0186] It should be noted that the methods described herein describe possible specific implementations. Operations and steps may be rearranged or otherwise modified, and other specific implementations are possible. Furthermore, aspects from two or more of these methods may be combined.

[0187] While aspects of LTE, LTE-A, LTE-A Pro, or NR systems may be described for illustrative purposes, and the terms LTE, LTE-A, LTE-A Pro, or NR may be used in most of the description, the techniques described herein are also applicable to networks outside of LTE, LTE-A, LTE-A Pro, or NR networks. For example, the techniques described are applicable to a variety of other wireless communication systems, such as Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM, and other systems and radio technologies not explicitly mentioned herein.

[0188] The information and signals described herein can be represented using any of a variety of different techniques and skills. For example, data, instructions, commands, information, signals, bits, symbols, and chips mentioned throughout the description can be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, light fields or optical particles, or any combination thereof.

[0189] The various exemplary blocks and components described herein can be implemented or performed using a general-purpose processor, DSP, ASIC, CPU, graphics processing unit (GPU), (neural processing unit) NPU, FPGA or other programmable logic device, discrete gate or transistor logic unit, discrete hardware component, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in alternative embodiments, a processor may be any processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors working in conjunction with a DSP core, or any other such configuration). Any function or operation described herein that can be performed by a processor may be performed by multiple processors capable of performing the described function or operation individually or jointly.

[0190] The functions described herein can be implemented using hardware, software executed by a processor, firmware, or any combination thereof. When implemented using software executed by a processor, the functions can be stored as one or more instructions or code on a computer-readable medium or transmitted using one or more instructions or code on a computer-readable medium. Other examples and specific implementations are within the scope of this disclosure and the appended claims. For example, due to the nature of software, the functions described herein can be implemented using software executed by a processor, hardware, firmware, hardwiring, or any combination of these. Features implementing the functions can also be physically located in various locations, including various portions distributed such that the functions are implemented in different physical locations.

[0191] Computer-readable media includes both non-transitory computer storage media and communication media, encompassing any medium that facilitates the transfer of a computer program from one location to another. Non-transitory storage media can be any available medium accessible by a general-purpose or special-purpose computer. By way of example, and not limitation, non-transitory computer-readable media may include RAM, ROM, electrically erasable programmable ROM (EEPROM), flash memory, compressed optical disc (CD) ROM or other optical disc storage devices, magnetic disk storage devices or other magnetic storage devices, or any other non-transitory medium that can be used to carry or store desired program code components in the form of instructions or data structures, and accessible by a general-purpose or special-purpose computer or a general-purpose or special-purpose processor. Furthermore, any connection is appropriately referred to as computer-readable media. For example, if software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included within the definition of computer-readable media. As used herein, disks and optical discs include CDs, laser discs, optical discs, digital multifunction discs (DVDs), floppy disks, and Blu-ray discs. A disk can magnetically reproduce data, and an optical disc can optically reproduce data using a laser. Combinations of the above are also included within the scope of computer-readable media. Any function or operation described herein that can be performed by memory can be performed by multiple memories capable of performing the described function or operation individually or jointly.

[0192] As used herein, the word "or" in a list of items (e.g., a list of items accompanied by phrases such as "at least one of" or "one or more of") in the claims indicates an inclusive list, such that a list of at least one of, for example, A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Furthermore, as used herein, the phrase "based on" should not be construed as a reference to a closed set of conditions. For example, an example step described as "based on condition A" could be based on both condition A and condition B without departing from the scope of this disclosure. In other words, as used herein, the phrase "based on" should be interpreted in the same manner as the phrase "at least partially based on".

[0193] As used herein, including in claims, the article “a” preceding a noun is open-ended and is understood to refer to “at least one” or “one or more” of those nouns. Therefore, the terms “a,” “at least one,” “one or more,” and “at least one of one or more” are interchangeable. For example, where a claim enumerates “components” performing one or more functions, each of the individual functions may be performed by a single component or by any combination of multiple components. Thus, the term “component” having a characteristic or performing a function may refer to “at least one of one or more components” having a particular characteristic or performing a particular function. Subsequent references to a component introduced with the article “a” using the terms “the” or “the” may refer to any or all of the one or more components. For example, a component introduced with the article “a” may be understood to mean “one or more components,” and subsequent reference to “the component” in a claim may be understood to be equivalent to referring to “at least one of the one or more components.” Similarly, subsequent references to a component introduced with the terms “the” or “the” as “one or more components” may refer to any or all of those one or more components. For example, reference to "the one or more components" in the subsequent claims can be understood as equivalent to reference to "at least one of the one or more components".

[0194] The term "determine" encompasses a variety of actions, and therefore, "determine" can include calculation, computation, processing, derivation, investigation, searching (such as by searching in a table, database, or other data structure), ascertainment, etc. Furthermore, "determine" can include receiving (e.g., receiving information), accessing (e.g., accessing data stored in memory), etc. Moreover, "determine" can include parsing, obtaining, selecting, choosing, creating, and other similar actions.

[0195] In the accompanying drawings, similar components or features may have the same reference numerals. Furthermore, various components of the same type can be distinguished by adding a dash after the reference numeral and a second reference numeral to differentiate between similar components. If only the first reference numeral is used in the description, the description applies to any one of the similar components having the same first reference numeral, regardless of the second or other subsequent reference numerals.

[0196] The description herein, illustrated with reference to the accompanying drawings, describes an example configuration and does not represent all achievable examples or those within the scope of the claims. The term "example" as used herein means "serving as an example, instance, or illustration," not "preferred" or "advantageous over other examples." The detailed description includes specific details used to provide an understanding of the described techniques. However, these techniques can be practiced without these specific details. In some figures, known structures and devices are shown in block diagram form to avoid obscuring the concept of the described examples.

[0197] The description herein is provided to enable those skilled in the art to implement or use this disclosure. Various modifications to this disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the scope of this disclosure. Therefore, this disclosure is not limited to the examples and designs described herein, but should be granted the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A wireless device, the wireless device comprising: One or more memories, wherein the one or more memories store processor-executable code; and One or more processors, coupled to one or more memories and capable of operating individually or jointly to execute the code to enable the wireless device: Receive information indicating the non-uniform probability distribution of the modulation constellation used for multiple-input multiple-output (MIMO) signals; Receive the symbols of the MIMO signal, the MIMO signal being modulated using the non-uniform probability distribution; and The symbol is demodulated at least in part based on the transformation of the modulation constellation to a subspace using the dimension associated with the non-uniform probability distribution and the point of the transformed modulation constellation closest to the projected symbol corresponding to the symbol in the subspace.

2. The wireless device of claim 1, wherein, in order to demodulate the symbol, the one or more processors are capable of operating individually or jointly to execute the code to cause the wireless device to: project the symbol into the subspace to generate the projected symbol, thereby determining the point of the transformed modulation constellation closest to the projected symbol.

3. The wireless device of claim 1, wherein the one or more processors are further capable of operating individually or jointly to execute the code to cause the wireless device to: The received signal is used to generate a channel estimate, the symbols being received via the channel. The transformation of the modulation constellation includes the transformation of the channel estimation and the combination of the modulation constellation.

4. The wireless device of claim 1, wherein the number of dimensions associated with the non-uniform probability distribution is associated with the number of layers of the MIMO signal.

5. The wireless device of claim 4, wherein the subspace comprises a number of dimensions twice the number of layers of the MIMO signal and is associated with a space four times the number of layers of the MIMO signal.

6. The wireless device of claim 1, wherein the one or more processors are further capable of operating individually or jointly to execute the code to cause the wireless device to: The non-discrete estimation of the symbol vector of the symbol, which comprises multiple symbol layers, is decoded to determine the point of the transformed modulation constellation closest to the projected symbol.

7. The wireless device of claim 1, wherein the non-uniform probability distribution is associated with a first layer of the MIMO signal, and the one or more processors are further capable of operating individually or jointly to execute the code to cause the wireless device to: The second symbol of the second layer of the MIMO signal is received, wherein the second layer of the MIMO signal is modulated with a second non-uniform probability distribution different from the non-uniform probability distribution associated with the first layer; and The second symbol of the second layer of the MIMO signal is demodulated at least in part based on a second transformation of the modulation constellation in the second subspace using a dimension associated with the second non-uniform probability distribution and a second point of the transformed modulation constellation that is closest to the second symbol in the second subspace.

8. The wireless device of claim 7, wherein the one or more processors are further capable of operating individually or jointly to execute the code to cause the wireless device to: Receive an indication of the second non-uniform probability distribution associated with the second layer of the MIMO signal.

9. The wireless device according to claim 1, wherein the modulation constellation is a quadrature amplitude modulation (QAM) constellation.

10. A method for wireless communication by a wireless device, the method comprising: Receive information indicating the non-uniform probability distribution of the modulation constellation used for multiple-input multiple-output (MIMO) signals; Receive the symbols of the MIMO signal, the MIMO signal being modulated using the non-uniform probability distribution; and The symbol is demodulated at least in part based on the transformation of the modulation constellation to a subspace using the dimension associated with the non-uniform probability distribution and the point of the transformed modulation constellation closest to the projected symbol corresponding to the symbol in the subspace.

11. The method of claim 10, wherein demodulating the symbols comprises: The symbol is projected onto the subspace to generate the projected symbol, thereby determining the point of the transformed modulation constellation closest to the projected symbol.

12. The method according to claim 10, further comprising: The received signal is used to generate a channel estimate, the symbols being received via the channel. The transformation of the modulation constellation includes the transformation of the channel estimation and the combination of the modulation constellation.

13. The method of claim 10, wherein the number of dimensions associated with the non-uniform probability distribution is associated with the number of layers of the MIMO signal.

14. The method of claim 13, wherein the subspace comprises a number of dimensions twice the number of layers of the MIMO signal and is associated with a space four times the number of layers of the MIMO signal.

15. The method according to claim 10, further comprising: The non-discrete estimation of the symbol vector of the symbol, which comprises multiple symbol layers, is decoded to determine the point of the transformed modulation constellation closest to the projected symbol.

16. The method of claim 10, wherein the non-uniform probability distribution is associated with a first layer of the MIMO signal, the method further comprising: The second symbol of the second layer of the MIMO signal is received, wherein the second layer of the MIMO signal is modulated with a second non-uniform probability distribution different from the non-uniform probability distribution associated with the first layer; and The second symbol of the second layer of the MIMO signal is demodulated at least in part based on a second transformation of the modulation constellation in the second subspace using a dimension associated with the second non-uniform probability distribution and a second point of the transformed modulation constellation that is closest to the second symbol in the second subspace.

17. The method according to claim 16, further comprising: Receive an indication of the second non-uniform probability distribution associated with the second layer of the MIMO signal.

18. The method of claim 10, wherein the modulation constellation is a quadrature amplitude modulation (QAM) constellation.

19. A non-transitory computer-readable medium storing code, the code comprising instructions executable by one or more processors to: Receive information indicating the non-uniform probability distribution of the modulation constellation used for multiple-input multiple-output (MIMO) signals; Receive the symbols of the MIMO signal, the MIMO signal being modulated using the non-uniform probability distribution; and The symbol is demodulated at least in part based on the transformation of the modulation constellation to a subspace using the dimension associated with the non-uniform probability distribution and the point of the transformed modulation constellation closest to the projected symbol corresponding to the symbol in the subspace.

20. The non-transitory computer-readable medium of claim 19, wherein, in order to demodulate the symbol, the code includes instructions executable by one or more processors to: project the symbol into the subspace to generate the projected symbol, and determine the point of the transformed modulation constellation closest to the projected symbol.

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