CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority to U.S. Provisional Patent Application No. 63/128,801 filed December 21, 2020, entitled “METHOD FOR CHANNEL STATE INFORMATION (CSI) SIGNAL IN WIRELESS COMMUNICATION SYSTEM,” which is hereby incorporated by reference in its entirety.

BACKGROUND

[0002] Embodiments of the present disclosure relate to an apparatus and method for using a channel state information reference signal in wireless communications. Specifically, embodiments relate to an apparatus and method for using a channel state information reference signal in wireless communication, such as in an orthogonal frequency division multiplexing (OFDM) system.

[0003] Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Orthogonal frequency division multiplexing (OFDM) is one of the most widely used and adopted digital multicarrier methods and has been used extensively for cellular communications, such as 4th-generation (4G) Long Term Evolution (LTE) and 5th-generation (5G) New Radio (NR).

SUMMARY

[0004] Embodiments of an apparatus and method for using a channel state information reference signal (CSLRS) in an OFDM system are disclosed herein.

[0005] In one example, an apparatus including at least one processor and a memory storing instructions is disclosed. The instructions, when executed by the at least one processor, cause the apparatus to transmit a channel state information reference signal (CSLRS) to a receiver. The instructions, when executed by the at least one processor, further cause the apparatus to encode traffic resource element for channel state information (TR-CSI) resource elements. The instructions, when executed by the at least one processor, further cause the apparatus to modulate the encoded TR-CSI resource elements. The instructions, when executed by the at least one processor, further cause the apparatus to transmit the modulated TR-CSI resource elements to the receiver over a TR-CSI path. The instructions, when executed by the at least one processor, further cause the apparatus to receive channel state information from the receiver based on the CSI-RS and the TR-CSI resource elements, as reconstructed by the receiver.

[0006] In another example, a method for wireless communication is disclosed. The method includes transmitting a channel state information reference signal (CSI-RS) to a receiver. The method further includes encoding traffic resource element for channel state information (TR-CSI) resource elements. The method further includes modulating the encoded TR-CSI resource elements. The method further includes transmitting the modulated TR-CSI resource elements to the receiver over a TR-CSI path. The method further includes receiving channel state information from the receiver based on the CSI-RS and the TR-CSI resource elements, as reconstructed by the receiver.

[0007] In another example, a baseband chip is disclosed. The baseband chip includes a channel state information reference signal transmission circuit. The channel state information reference signal transmission circuit is configured to transmit a channel state information reference signal (CSI-RS) to a receiver. The baseband chip further includes a traffic resource element for channel state information (TR-CSI) encoding circuit. The TR-CSI encoding circuit is configured to encode TR-CSI resource elements. The baseband chip further includes a TR-CSI modulating circuit. The TR-CSI modulating circuit is configured to modulate the TR-CSI resource elements. The baseband chip further includes a TR-CSI transmission circuit. The TR-CSI transmission circuit is configured to transmit the modulated TR-CSI resource elements to the receiver over a TR-CSI path to the receiver. The baseband chip further includes a channel information circuit. The channel information circuit is configured to receive channel state information from the receiver based on the CSI-RS and the TR-CSI resource elements, as reconstructed by the receiver.

[0008] In another example, an apparatus for wireless communication including at least one processor and a memory storing instructions is disclosed. The instructions, when executed by the at least one processor, cause the apparatus to receive a channel state information reference signal (CSI-RS) from a transmitter. The instructions, when executed by the at least one processor, further cause the apparatus to estimate first channel information using the CSI-RS. The instructions, when executed by the at least one processor, further cause the apparatus to receive traffic resource element for channel state information (TR-CSI) resource elements from the transmitter using the first channel information over a TR-CSI path. The instructions, when executed by the at least one processor, further cause the apparatus to reconstruct the TR-CSI resource elements. The instructions, when executed by the at least one processor, cause the apparatus to estimate second channel information using the CSI-RS and the reconstructed TR-CSI resource elements.

[0009] In another example, a method for wireless communication is disclosed. The method includes receiving a channel state information reference signal (CSI-RS) from a transmitter. The method further includes estimating first channel information using the CSI-RS. The method further includes receiving traffic resource element for channel state information (TR-CSI) resource elements from the transmitter using the first channel information over a TR-CSI path. The method further includes reconstructing the TR-CSI resource elements. The method further includes estimating second channel information using the CSI-RS and the reconstructed TR-CSI resource elements.

[0010] In another example, a baseband chip is disclosed. The baseband chip includes a channel state information reference signal (CSI-RS) receiving circuit. The CSI-RS receiving circuit is configured to receive a CSI-RS from a transmitter. The baseband chip further includes a first channel estimation circuit. The first channel estimation circuit is configured to estimate first channel information using the CSI-RS. The baseband chip further includes a traffic resource element for channel state information (TR-CSI) receiving circuit. The TR-CSI receiving circuit is configured to receive TR-CSI resource elements from the transmitter using the first channel information over a TR-CSI path. The baseband chip further includes a reconstruction circuit. The reconstruction circuit is configured to reconstruct the TR-CSI resource elements. The baseband chip further includes a second channel estimation circuit. The second channel estimation circuit is configured to estimate second channel information using the CSI-RS and the reconstructed TR- CSI resource elements.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate embodiments of the present disclosure and, together with the description, further serve to explain the principles of the present disclosure and to enable a person skilled in the pertinent art to make and use the present disclosure.

[0012] FIG. 1 illustrates a wireless network, according to some embodiments of the present disclosure.

[0013] FIG. 2 illustrates an example of a reference signal (RS) configuration.

[0014] FIGS. 3A and 3B illustrate block diagrams of an apparatus including a host chip, a radio frequency (RF) chip, and a baseband chip implementing a wireless communication system, according to some embodiments of the present disclosure.

[0015] FIG. 4 is a block diagram of an apparatus for CSI-RS transmission, according to some embodiments of the present disclosure.

[0016] FIG. 5 is a block diagram of an apparatus for CSI-RS reception, according to some embodiments of the present disclosure. [0017] FIG. 6 is a sequence diagram for an apparatus for CSI-RS transmission and reception, according to some embodiments of the present disclosure.

[0018] FIG. 7 illustrates a flowchart of a method for CSI-RS transmission, according to some embodiments of the present disclosure.

[0019] FIG. 8 illustrates a flowchart of a method for CSI-RS reception, according to some embodiments of the present disclosure.

[0020] FIG. 9 illustrates a block diagram of a transmission apparatus, according to some embodiments of the present disclosure.

[0021] FIG. 10 is a diagram illustrating different types of TR-CSI and CSI-RS arrangements in transmitted data, according to some embodiments of the present disclosure.

[0022] FIG. 11 illustrates a block diagram of a communications device, according to some embodiments of the present disclosure.

[0023] Embodiments of the present disclosure will be described with reference to the accompanying drawings.

DETAILED DESCRIPTION

[0024] Although specific configurations and arrangements are discussed, it should be understood that this is done for illustrative purposes only. A person skilled in the pertinent art will recognize that other configurations and arrangements can be used without departing from the spirit and scope of the present disclosure. It will be apparent to a person skilled in the pertinent art that the present disclosure can also be employed in a variety of other applications.

[0025] It is noted that references in the specification to “one embodiment,” “an embodiment,” “an example embodiment,” “some embodiments,” “certain embodiments,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases do not necessarily refer to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it would be within the knowledge of a person skilled in the pertinent art to effect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0026] In general, terminology may be understood at least in part from usage in context. For example, the term “one or more” as used herein, depending at least in part upon context, may be used to describe any feature, structure, or characteristic in a singular sense or may be used to describe combinations of features, structures, or characteristics in a plural sense. Similarly, terms, such as “a,” “an,” or “the,” again, may be understood to convey a singular usage or to convey a plural usage, depending at least in part upon context. In addition, the term “based on” may be understood as not necessarily intended to convey an exclusive set of factors and may, instead, allow for existence of additional factors not necessarily expressly described, again, depending at least in part on context.

[0027] Various aspects of wireless communication systems will now be described with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, units, components, circuits, steps, operations, processes, algorithms, etc. (collectively referred to as “elements”). These elements may be implemented using electronic hardware, firmware, computer software, or any combination thereof. Whether such elements are implemented as hardware, firmware, or software depends upon the particular application and design constraints imposed on the overall system.

[0028] The techniques described herein are principally described in the context of the operation of an orthogonal frequency division multiplexing (OFDM) or an orthogonal frequency division multiple access (OFDMA) system. However, to the extent they are relevant, the techniques and ideas described herein may also be used for and in combination with various wireless communication networks, such as code division multiple access (CDMA) system, time division multiple access (TDMA) system, frequency division multiple access (FDMA) system, single-carrier frequency division multiple access (SC-FDMA) system, and other networks. For example, networks may include but are not limited to 4G LTE, and 5G NR cellular networks, as well as WI-FI wireless networks. The terms “network” and “system” are often used interchangeably. The techniques described herein may be used for the wireless networks mentioned above, as well as other wireless networks, though they are particularly adapted to and explained in the context of OFDM or OFDMA systems.

[0029] Orthogonal frequency-division multiple access (OFDMA) is a multi-user version of the popular orthogonal frequency-division multiplexing OFDM) digital modulation scheme. Multiple access is achieved in OFDMA by assigning subsets of subcarriers to individual users. This allows simultaneous low-data-rate transmission from several users.

[0030] In an OFDM or OFDMA communication system, a channel state information reference signal (CSI-RS) is used to estimate a terminal’s channel state information (CSI), and the terminal or base station uses CSI-RS to determine the best downlink transmission format. A CSI- RS in 5G is a known pseudo-random sequence initialized by different known parameters. Thus, the CSI-RS is a predefined known sequence. However, the CSI-RS is overhead because it does not send any useful information bits. Thus, the more resources the CSI-RS uses, the lower the spectral efficiency of overall transmission. Spectral efficiency is defined as the number of bits transmitted in a Hz. There are different methods to achieve higher spectral efficiency, including but not limited to higher modulation and control scheme (MCS), higher multiple-input and multiple-output (MIMO) rank, etc.

[0031] As described above, in OFDM or OFDMA communications, it may be necessary to use a channel state information reference signal (CSI-RS) to estimate a terminal’s channel state. The solutions in the present disclosure send traffic resource elements (RE) with the same beamforming as the CSI-RS to assist CSI measurement and reduce resources otherwise occupied by a CSI-RS. Such an approach may help to improve spectral efficiency significantly, especially when a channel changes very slowly in a time direction and/or frequency direction.

[0032] Therefore, an aspect of the present disclosure is to replace part of CSI-RS resources that would otherwise constitute overhead with traffic RE sent at a format with which UE can receive it correctly in the DL. Such specialized traffic is referred to as traffic RE for CSI (TR-CSI). At a receiver (e.g., the user equipment (UE)), a coarse channel estimation is obtained using a CSI- RS, and then TR-CSI may be received first. A correctly received TR-CSI may be used to reconstruct transmitted TR-CSI. Then, a fine channel state estimation is obtained according to the CSI-RS and the reconstructed TR-CSI.

[0033] As a DL-only signal, the CSI-RS the UE receives is used to estimate the channel and report channel quality information back to the gNB (or another base station). During multipleinput and multiple-output (MIMO) operations, new radio (NR) uses different antenna approaches based on the carrier frequency. At lower frequencies, the system uses a modest number of active antennas for multiple-user MIMO (MU-MIMO) and adds frequency division duplex (FDD) operations. In this case, the user equipment (UE) needs the CSI-RS to calculate the CSI and report it back in the UL direction.

[0034] Thus, CSI-RS refers to channel state information reference signal, and these signals are downlink only signals. The CSI-RS is used for DL CSI acquisition, such as being used for received signal received power (RSRP) measurements used during mobility and beam management.

[0035] The CSI-RS is also used for frequency/time tracking, demodulation, and UL reciprocity -based precoding. A CSI-RS is configured specifically to a UE, but multiple users may also share the same resource.

[0036] The 5G NR standard allows for a high level of flexibility in CSI-RS configurations, such that a resource may be configured to have up to 32 ports. A CSI-RS resource may start at any OFDM symbol of the slot, and a CSI-RS resource usually occupies 1/2/4 OFDM symbols depending upon a configured number of ports. A CSI-RS may be periodic, semi -persistent, or aperiodic (due to downlink control information (DCI) triggering). For time/frequency tracking, CSI-RS may either be periodic or aperiodic. The CSI-RS is transmitted in bursts of two or four symbols that are spread across one or two slots.

[0037] To clarify, a coarse channel estimation may be referred to as a first channel estimation, and a fine channel estimation may be referred to as a second channel estimation. These channel estimations differ in that the coarse (first) channel estimation provides a channel estimation of a same or lower channel quality as a channel quality of the fine (second) channel estimation.

[0038] FIG. 1 illustrates a wireless network 100, in which certain aspects of the present disclosure may be implemented, according to some embodiments of the present disclosure. As shown in FIG. 1, wireless network 100 may include a network of nodes, such as a user equipment (UE) 102, an access node 104, and a core network element 106. User equipment 102 may be any terminal device, such as a mobile phone, a desktop computer, a laptop computer, a tablet, a vehicle computer, a gaming console, a printer, a positioning device, a wearable electronic device, a smart sensor, or any other device capable of receiving, processing, and transmitting information, such as any member of a vehicle to everything (V2X) network, a cluster network, a smart grid node, or an Internet-of-Things (loT) node. It is understood that user equipment 102 is illustrated as a mobile phone simply by way of illustration and not by way of limitation.

[0039] Access node 104 may be a device that communicates with UE 102, such as a wireless access point, a base station (BS), a Node B, an enhanced Node B (eNodeB or eNB), a next-generation NodeB (gNodeB or gNB), a cluster master node, or the like. Access node 104 may have a wired connection to UE 102, a wireless connection to UE 102, or any combination thereof. Access node 104 may be connected to UE 102 by multiple connections, and UE 102 may be connected to other access nodes in addition to access node 104. Access node 104 may also be connected to other UEs. It is understood that access node 104 is illustrated by a radio tower by way of illustration and not by way of limitation.

[0040] Core network element 106 may serve access node 104 and user equipment 102 to provide core network services. Examples of core network element 106 may include a home subscriber server (HSS), a mobility management entity (MME), a serving gateway (SGW), or a packet data network gateway (PGW). These are examples of core network elements of an evolved packet core (EPC) system, which is a core network for the LTE system. Other core network elements may be used in LTE and in other communication systems. In some embodiments, core network element 106 includes an access and mobility management function (AMF) device, a session management function (SMF) device, or a user plane function (UPF) device, of a core network for the NR system. It is understood that core network element 106 is shown as a set of rack-mounted servers by way of illustration and not by way of limitation.

[0041] Core network element 106 may connect with a large network, such as the Internet 108, or another Internet Protocol (IP) network, to communicate packet data over any distance. In this way, data from user equipment 102 may be communicated to other user equipment connected to other access points, including, for example, a computer 110 connected to Internet 108, for example, using a wired connection or a wireless connection, or to a tablet 112 wirelessly connected to Internet 108 via a router 114. Thus, computer 110 and tablet 112 provide additional examples of possible user equipment, and router 114 provides an example of another possible access node.

[0042] A generic example of a rack-mounted server is provided as an illustration of core network element 106. However, there may be multiple elements in the core network including database servers, such as a database 116, and security and authentication servers, such as an authentication server 118. Database 116 may, for example, manage data related to user subscriptions to network services. A home location register (HLR) is an example of a standardized database of subscriber information for a cellular network. Likewise, authentication server 118 may handle authentication of users, sessions, and so on. In the NR system, an authentication server function (AUSF) device may be the specific entity to perform user equipment authentication. In some embodiments, a single server rack may handle multiple such functions, such that the connections between core network element 106, authentication server 118, and database 116, may be local connections within a single rack.

[0043] As described below in greater detail, in some embodiments, wireless communication can be established between any suitable nodes in wireless network 100, such as between UE 102 and access node 104, and between UE 102 and core network element 106 for sending and receiving data (e.g., OFDMA symbol(s)). A transmitting node (e.g., a BS) may generate the OFDMA symbol(s) and transmit the symbol to a receiving device (e.g., a UE). When the receiving device receives the symbol(s), the receiver may perform the methods described in the present disclosure to use both a reference signal and a data signal to improve the ability of the receiver to successfully receive the symbol(s).

[0044] Each node of wireless network 100 in FIG. 1 that is suitable for the reception of signals, such as OFDMA signals, may be considered as a communications device. More detail regarding the possible implementation of a communications device is provided by way of example in the description of a communications device 1100 in FIG. 11. Communications device 1100 may be configured as user equipment 102, access node 104, or core network element 106 in FIG. 1. Similarly, communications device 1100 may also be configured as computer 110, router 114, tablet 112, database 116, or authentication server 118 in FIG. 1. As shown in FIG. 11, communications device 1100 may include a processor 1102, a memory 1104, and a transceiver 1106. These components are shown as connected to one another by a bus, but other connection types are also permitted. When communications device 1100 is user equipment 102, additional components may also be included, such as a user interface (UI), sensors, and the like. Similarly, communications device 1100 may be implemented as a blade in a server system when communications device 1100 is configured as core network element 106. Other implementations are also possible, and these enumerated examples are not to be taken as limiting.

[0045] Transceiver 1106 may include any suitable device for sending and/or receiving data. Communications device 1100 may include one or more transceivers, although only one transceiver 1106 is shown for simplicity of illustration. An antenna 1108 is shown as a possible communication mechanism for communications device 1100. If the communication is multipleinput and multiple-output (MIMO), multiple antennas and/or arrays of antennas may be utilized for such communication. Additionally, examples of communications device 1100 may communicate using wired techniques rather than (or in addition to) wireless techniques. For example, access node 104 may communicate wirelessly to user equipment 102 and may communicate by a wired connection (for example, by optical or coaxial cables) to core network element 106. Other communication hardware, such as a network interface card (NIC), may be included in communications device 1100 as well.

[0046] As shown in FIG. 11, communications device 1100 may include processor 1102. Although only one processor is shown, it is understood that multiple processors can be included. Processor 1102 may include microprocessors, microcontrollers, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functions described throughout the present disclosure. Processor 1102 may be a hardware device having one or more processing cores. Processor 1102 may execute software. Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. Software can include computer instructions written in an interpreted language, a compiled language, or machine code. Other techniques for instructing hardware are also permitted under the broad category of software. [0047] As shown in FIG. 11, communications device 1100 may also include memory 1104. Although only one memory is shown, it is understood that multiple memories can be included. Memory 1104 can broadly include both memory and storage. For example, memory 1104 may include random-access memory (RAM), read-only memory (ROM), static RAM (SRAM), dynamic RAM (DRAM), ferro-electric RAM (FRAM), electrically erasable programmable ROM (EEPROM), CD-ROM or other optical disk storage, hard disk drive (HDD), such as magnetic disk storage or other magnetic storage devices, Flash drive, solid-state drive (SSD), or any other medium that can be used to carry or store desired program code in the form of instructions that can be accessed and executed by processor 1102. Broadly, memory 1104 may be embodied by any computer-readable medium, such as a non-transitory computer-readable medium.

[0048] Processor 1102, memory 1104, and transceiver 1106 may be implemented in various forms in communications device 1100 for performing wireless communication with channel state information signal management functions. In some embodiments, processor 1102, memory 1104, and transceiver 1106 of communications device 1100 are implemented (e.g., integrated) on one or more system-on-chips (SoCs). In one example, processor 1102 and memory 1104 may be integrated on an application processor (AP) SoC (sometimes known as a “host,” referred to herein as a “host chip”) that handles application processing in an operating system environment, including generating raw data to be transmitted. In another example, processor 1102 and memory 1104 may be integrated on a baseband processor (BP) SoC (sometimes known as a modem, referred to herein as a “baseband chip”) that converts the raw data, e.g., from the host chip, to signals that can be used to modulate the carrier frequency for transmission, and vice versa, which can run a real-time operating system (RTOS). In still another example, processor 1102 and transceiver 1106 (and memory 1104 in some cases) may be integrated on an RF SoC (sometimes known as a transceiver, referred to herein as an “RF chip”) that transmits and receives RF signals with antenna 1108. It is understood that in some examples, some or all of the host chip, baseband chip, and RF chip may be integrated as a single SoC. For example, a baseband chip and an RF chip may be integrated in a single SoC that manages all the radio functions for cellular communication. [0049] Various aspects of the present disclosure related to channel state information signal management may be implemented as software and/or firmware elements executed by a generic processor in a baseband chip (e.g., a baseband processor). It is understood that in some examples, one or more of the software and/or firmware elements may be replaced by dedicated hardware components in the baseband chip, including integrated circuits (ICs), such as application-specific integrated circuits (ASICs). Mapping to the wireless communication (e.g., WI-FI, 4G, LTE, 5G, etc.) layer architecture, the implementation of the present disclosure may be at Layer 1, e.g., the physical (PHY) layer.

[0050] FIG. 2 illustrates an example of a reference signal (RS) configuration. The RS structure of 5G new radio (NR) basically follows that of long-term evolution (LTE) while achieving the flexibility to adapt to operation in various different frequency bands and scenarios. [0051] To increase protocol efficiency and to keep transmissions contained within a slot or beam without having to depend on other slots and beams, 5G NR introduces the following four main reference signals. Specifically, 5G NR introduces a demodulation reference signal (DMRS), a phase tracking reference signal (PT-RS), a sounding reference signal (SRS), and a channel state information reference signal (CSI-RS).

[0052] For example, these reference signals differentiate between NR and LTE. In NR, there is not a cell-specific reference signal (C-RS). Also, a new reference signal PT-RS has been introduced for time/frequency tracking. A DMRS is used for both downlink and uplink channels. Further, in NR, reference signals are transmitted only when necessary, by contrast from LTE, where always exchanges reference signals to manage the link.

[0053] The reference signals include a DMRS. The DMRS is specific for specific UE and is used to estimate the radio channel. The system is able to beamform the DMRS, keep it within a scheduled resource, and transmit it only when necessary, in either DL or UL. Further, multiple orthogonal DMRSs may be allocated to support MIMO transmission. Thus, the network presents users with DMRS information early on for the initial decoding requirement that low-latency applications need, but it only occasionally presents this information for low-speed scenarios in which the channel shows little change. In high-mobility scenarios, to track fast changes in a channel, a system might increase the rate of transmission of a DMRS signal (called “additional DMRS”). As noted above, DMRS refers to the demodulation reference signal. A DMRS is used by a receiver for radio channel estimation for demodulation of an associated physical channel DMRS design, and mapping is specific to each of Downlink (DL) and Uplink (UL) NR channels such as NR-PBCH, NR-PDCCH, NR-PDSCH, NR-PUSCH, and NR- PUSCH. A DMRS is specific for a specific UE and transmitted on demand. DMRS can be a beamformed DMRS, be kept within a scheduled resource, and transmit the DMRS only when necessary, in either DL or UL. Also, multiple orthogonal DMRSs can be allocated to support MIMO transmission.

[0054] The reference signals may also include a PT-RS. The phase noise of a transmitter increases as the frequency of operation increases. The PT-RS plays an important role, especially at mmWave frequencies, to minimize the effect of the oscillator phase noise on system performance. One of the main problems that phase noise introduces into an OFDM signal appears as a common phase rotation of all the sub-carriers, known as common phase error (CPE). As noted above, PT-RS stands for phase tracking reference signal. The main function of the PT-RS is to track a phase of the local oscillator at a transmitter and a receiver. A PT-RS enables suppression of phase noise and common phase error, especially at higher mm-wave frequencies. A PT-RS is present both in uplink (in NR-PUSCH) and downlink (in NR-PDSCH) channels.

[0055] Due to phase noise properties, a PT-RS has a low density in a frequency domain and a high density in a time domain. A PT-RS is associated with one DMRS port during transmission. Moreover, a PT-RS is confined to a scheduled bandwidth (BW) and a duration used for NR-PDSCH/NR-PUSCH. The NR system typically maps the PT-RS information to a few subcarriers per symbol because the phase rotation affects all sub-carriers within an OFDM symbol equally. However, the phase rotation shows a low correlation from symbol to symbol. The system configures the PT-RS depending on the quality of the oscillators, carrier frequency, subcarrier spacing, and modulation and coding schemes that the transmission uses.

[0056] The reference signals may also include an SRS. As a UL-only signal, the SRS is transmitted by the UE to help the gNB obtain the channel state information (CSI) for each user. CSI describes how the NR signal propagates from the UE to the gNB and represents the combined effect of scattering, fading, and power decay with distance. The system uses the SRS for resource scheduling, link adaptation, Massive MIMO, and beam management. As noted above, an SRS refers to a sounding reference signal and is an uplink-only signal. The SRS is configured specifically to a UE. In the time domain, an SRS spans 1/2/4 consecutive symbols which are mapped within the last six symbols of the slot. Multiple SRS symbols may allow coverage extension and increased sounding capacity. The design of an SRS and its frequency hopping mechanism are the same as that used in LTE for an SRS.

[0057] The reference signals may also include a CSI-RS. As a DL-only signal, the CSI-RS the UE receives is used to estimate the channel and report channel quality information back to the gNB. During MIMO operations, NR uses different antenna approaches based on the carrier frequency. At lower frequencies, the system uses a modest number of active antennas for MU- MIMO and adds frequency division duplex (FDD) operations. In this case, the UE requires the CSI-RS to calculate the CSI and reports it back in the UL direction. As noted above, CSI-RS refers to channel state information reference signal, and the CSI-RS signals themselves are downlink- only signals. For example, a CSI-RS is used for DL CSI acquisition. Also, a CSI-RS is used for RSRP measurements used during mobility and beam management, and also used for frequency/time tracking, demodulation, and UL reciprocity-based pre-coding. A CSI-RS is configured to be specific to a UE, but multiple users can also share the same resource. A 5G NR standard allows a high level of flexibility in CSI-RS configurations, such that a resource can be configured with up to 32 ports. A CSI-RS resource may start at any OFDM symbol of the slot, and it usually occupies 1/2/4 OFDM symbols depending upon the configured number of ports. A CSI- RS may be periodic, semi-persistent or aperiodic, due to downlink control information (DCI) triggering. For time/frequency tracking, a CSI-RS can either be periodic or aperiodic. A CSI-RS is transmitted in bursts of two or four symbols which are spread across one or two slots.

[0058] As described above, in high-frequency bands, phase noise would be a serious issue. Phase noise is phase fluctuation that occurs due to frequency components other than those of the carrier frequency in a local oscillator signal. Therefore, in NR, a Phase-Tracking Reference Signal (PT-RS) is newly specified as a UE-specific reference signal.

[0059] NR also involves beam control techniques. Beam control in LI (the first layer of the Open Systems Interconnection (OSI) reference model (physical layer)) and L2 (the second layer of the OSI reference model (data link layer)) can be divided into beam management and CSI acquisition. Beam management is a particularly effective technique at high frequencies and is generally aimed at establishing and maintaining transmitting/receiving analog beam pairs between the base station and user equipment. For example, the user equipment compares the LI -Reference Signal Received Power (RSRP) of multiple SS/PBCH blocks and CSI-RS to which different beams have been applied by the base station. Here, RSRP refers to the received power of a signal measured at a receiver. RSRP is used as an indicator of the receiver sensitivity of a mobile terminal. The user equipment selects a suitable transmit beam to be reported to the base station. The base station reports the beam information applied to the downlink channel so that the user equipment can select the corresponding reception beam to receive the downlink channel. A beam failure recovery technique is also specified, whereby user equipment that detects deterioration in the characteristics of a base station beam can request a switch to a different beam.

[0060] On the other hand, CSI acquisition is used for purposes such as determining the choice of transmission format. Transmission format refers to the number of layers or spatial streams transmitted simultaneously in MEMO, digital beams, and a Modulation and Coding Scheme (MCS). An MCS refers to combinations of modulation scheme and coding rate decided on beforehand when performing Adaptive Modulation and Coding. The codebook used for digital beam control may be specified as Type I and Type II, which have relatively low and relatively high quantization granularity, respectively. Quantization granularity refers to the spatial granularity of beams that are capable of being formed. In Type II, digital beam control refers to information about two beams and their linear combination. A linear combination refers to a linear sum of vectors. The vectors are multiplied by constant factors and added together. Then, information is reported to the base station, enabling beam control with higher spatial granularity.

[0061] Thus, FIG. 2 and the above description provide background for typical reference signals in 5G NR. These typical reference signals are modified, as described further below, in examples to improve performance.

[0062] FIGS. 3A and 3B illustrate block diagrams of an apparatus including a host chip, a radio frequency (RF) chip, and a baseband chip implementing a wireless communication system according to some embodiments of the present disclosure. For example, the apparatus provided in FIGS. 3A and 3B may implement a BS that sends reference signals in a DL or implement a UE that receives reference signals in a DL, such that the reference signals improve the use of a CSL RS.

[0063] It is contemplated that the wireless communication systems described above may be implemented either in software or hardware. For example, FIGS. 3A and 3B illustrate block diagrams of a wireless communication system 300 including a host chip, an RF chip, and a baseband chip implementing a wireless communication system with channel state information signal management as presented in FIGS. 4-5 in software and hardware, according to some embodiments of the present disclosure. Wireless communication system 300 may be an example of any node of wireless network 100 in FIG. 1 suitable for signal reception, such as user equipment 102 or a core network element 106. As shown in FIGS. 3 A and 3B, wireless communication system 300 may include an RF chip 302, a baseband chip 304A in FIG. 3 A or baseband chip 304B in FIG. 3B, a host chip 306, and an antenna 310. In some embodiments, baseband chip 304A or 304B is implemented by processor 1102 and memory 1104, and RF chip 302 is implemented by processor 1102, memory 1104, and transceiver 1106, as described in greater detail with respect to FIG. 11. Besides on-chip memory 312 (also known as “internal memory,” e.g., as registers, buffers, or caches) on each chip 302, 304 A or 304B, or 306, wireless communication system 300 may further include a system memory 308 (also known as the main memory) that can be shared by each chip 302, 304A or 304B, or 306 through the main bus. Baseband chip 304A or 304B is illustrated as a standalone system on a chip (SoC) in FIGS. 3A and 3B. However, it is understood that in one example, baseband chip 304A or 304B and RF chip 302 may be integrated as one SoC; in another example, baseband chip 304 A or 304B and host chip 306 may be integrated as one SoC; in still another example, baseband chip 304A or 304B, RF chip 302, and host chip 306 may be integrated as one SoC, as described above.

[0064] A CSI-RS may be sent in a downlink from a BS to a UE. Thus, the description presented herein should be understood accordingly.

[0065] In the uplink, host chip 306 may generate original data and send it to baseband chip 304 A or 304B for encoding, modulation, and mapping. Baseband chip 304 A or 304B may access the original data from host chip 306 directly using an interface 314 or through system memory 308 and then process the data for transmission by performing the functions for channel state information signal management of modules 902, 904, 906, 908, 910, 912 and 920, by using the TR-CSI data path, along with the generation of the CSI-RS at module 940 as described further, below, in detail with respect to FIG. 9, as non-limiting examples. This information is then prepared for transmission by resource mapping module 950. Baseband chip 304A or 304B then may pass the modulated signal (e.g., the OFDMA symbol) to RF chip 302 through interface 314. A transmitter (Tx) 316 of RF chip 302 may convert the modulated signals in the digital form from baseband chip 304A or 304B into analog signals, i.e., RF signals, and transmit the RF signals through antenna 310 into the channel.

[0066] In the downlink, antenna 310 may receive the RF signals (e.g., the OFDMA symbol) through the channel and pass the RF signals to a receiver (Rx) 318 of RF chip 302. RF chip 302 may perform any suitable front-end RF functions, such as filtering, down-conversion, or samplerate conversion, and convert the RF signals into low-frequency digital signals (baseband signals) that can be processed by baseband chip 304 A or 304B. In the downlink, interface 314 of baseband chip 304A or 304B may receive the baseband signals, for example, the OFDMA symbol. Baseband chip 304 A or 304B then may perform the receiving functions of the elements of FIG. 5, described in further detail below. The original data may be extracted by baseband chip 304 A or 304B from the baseband signals and passed to host chip 306 through interface 314 or stored into system memory 308.

[0067] In some embodiments, the channel state information signal management schemes disclosed herein (e.g., by wireless communication system 300) may be implemented in firmware and/or software by baseband chip 304A in FIG. 3A having a channel state information module, which may include firmware and/or software, where the CSI module may be implemented and executed by a CSI processor, such as baseband processor 320 executing the stored instructions, as illustrated in FIG. 3A. Baseband processor 320 may be a generic processor, such as a central processing unit or a digital signal processor (DSP), not dedicated to channel state information signal management. That is, baseband processor 320 is also responsible for any other functions of baseband chip 304 A and can be interrupted when performing channel state information signal management due to other processes with higher priorities. Each element in apparatus 300 may be implemented as a software module executed by baseband processor 320 to perform the respective functions described above in detail.

[0068] In some other embodiments, the channel state information signal management schemes disclosed herein, for example, by wireless communication system 200, may be implemented in hardware by baseband chip 304B in FIG. 3B having a dedicated channel state information circuit 322, such as channel state information circuit 322, as illustrated in FIG. 3B. Channel state information circuit 322 may include one or more integrated circuits (ICs), such as application-specific integrated circuits (ASICs), dedicated to implementing the channel state information signal management schemes disclosed herein. Each element in wireless communication system 300 may be implemented as a circuit to perform the respective functions described above in detail. One or more microcontrollers (not shown) in baseband chip 304B may be used to program and/or control the operations of channel state information circuit 322. It is understood that in some examples, the channel state information signal management schemes disclosed herein may be implemented in a hybrid manner, e.g., in both hardware and software. For example, some elements in wireless communication system 300 may be implemented as a software module executed by baseband processor 320, while some elements in wireless communication system 300 may be implemented as circuits.

[0069] FIG. 4 is a block diagram of an apparatus for CSI-RS transmission 400, according to some embodiments of the present disclosure. For example, FIG. 4 illustrates a CSI-RS transmission circuit 410 and a TR-CSI transmission circuit 420. The CSI-RS transmission circuit 410 generates and transmits a CSI-RS signal in order to facilitate determining a DL channel state, as described above. However, because some of the information that would otherwise be communicated by a CSI-RS signal is instead replaced by information transmitted by the TR-CSI the CSI-RS uses fewer resources.

[0070] Moreover, FIG. 4 illustrates a TR-CSI transmission circuit 420. FIG. 4 corresponds to FIG. 9 in that FIG. 4 illustrates specific circuits used to perform the TR-CSI transmission. Specifically, FIG. 4 includes an encoding circuit 422, a rate matching circuit 424, an interleaving circuit 426, a modulating circuit 428, an add OCC circuit 430, a layer mapping circuit 432, and an antenna port mapping circuit 434. These constituent circuits correspond to the relevant modules of FIG. 9 and illustrate how the functionality of FIG. 9 may be implemented in appropriate portions of specialized hardware.

[0071] FIG. 5 is a block diagram of an apparatus for CSI-RS reception, according to some embodiments of the present disclosure. The channel state information signal management apparatus 500 includes a number of constituent circuits that correspond to the operations performed by a receiver at FIG. 8. Specifically, the channel state information signal management apparatus 500 includes a CSI-RS receiving circuit 510, a coarse channel estimation circuit 512, a TR-CSI receiving circuit 514, a reconstruction circuit 516, and a fine channel estimation circuit 518. These elements correspond to the relevant method operations of FIG. 8 and are implemented accordingly.

[0072] FIG. 6 is a sequence diagram for an apparatus for CSI-RS transmission and reception 600, according to some embodiments of the present disclosure.

[0073] FIG. 6 is a sequence diagram showing interactions between a base station and a user equipment in a channel state information signal management process. Thus, FIG. 6 shows how the base station (BS) sends information to the user equipment (UE), and how the UE processes the information it receives from the BS.

[0074] Accordingly, in operation S602, the BS generates and transmits a CSI-RS. As described, the CSI-RS is a reference signal that aids in determining the best downlink transmission format. However, the sent CSI-RS is able to use fewer occupied resources because of the use of the TR-CSI approach to substitute for portions of the CSI-RS that would otherwise be required. [0075] In operation S604, the BS generates and transmits a TR-CSI signal. Such a signal includes traffic bits, but these bits are formed in a way that the TR-CSI signal also aids in replacing part of the CSI-RS. For example, ways of generating such a TR-CSI signal are presented in FIG. 9.

[0076] In operation S606, the UE receives the CSI-RS from the BS. In operation S608, the UE performs a coarse channel estimation based on the CSI-RS. The coarse channel estimation information is used by the UE to process the TR-CSI resource elements. In operation S610, the UE receives TR-CSI resource elements. In operation S612, the UE reconstructs the TR-CSI signal. [0077] As described, based on the way the TR-CSI signal is formed, the TR-CSI can be reconstructed even if fewer resources are used for the CSI-RS. Thus, in operation S612, the UE reconstructs the TR-CSI signal. In operation S614, the reconstructed TR-CSI signal is used to perform a fine channel estimation by the UE. Such a fine channel estimation can be provided to the BS for optimal downlink communication. In this manner, it is possible to determine the best downlink transmit format while minimizing overhead that would otherwise be required to send the full CSI-RS.

[0078] FIG. 7 illustrates a flowchart of a method for CSI-RS transmission 700, according to some embodiments of the present disclosure.

[0079] In operation S702, the method transmits a CSI-RS. As described above, such a CSI- RS may use fewer resource than would otherwise be required because the TR-CSI substitutes for some of the resources that would otherwise be used for a CSI-RS. Hence, the TR-CSI is only sufficient to obtain a coarse channel estimation, rather than a fine channel estimation, but reduces overhead.

[0080] In operation S704, the method encodes TR-CSI resource elements. At operation S706, the method performs rate matching. At operation S708, the method performs interleaving. At operation S710, the method modulates the encoded TR-CSI resource elements. At operation S712, the method adds orthogonal cover codes (OCC) to the encoded TR-CSI resource elements. At operation S714, the method performs layer mapping. At operation S716, the method performs antenna port mapping. The specific details of these method steps are provided in conjunction with the description of the corresponding modules in FIG. 9.

[0081] At operation S730, the method concludes in that the TR-CSI resource elements are also transmitted. Once received, the TR-CSI resource elements may be used for the fine channel estimation as described further above. [0082] As described above, the TR-CSI resource elements substitute for portions of the CSI-RS that would otherwise be used for channel state estimation. As a result, once the TR-CSI resource elements are sent and received, the receiver is able to obtain a better fine channel estimation.

[0083] FIG. 8 illustrates a flowchart of a method for CSI-RS reception 800, according to some embodiments of the present disclosure.

[0084] In operation S802, the method receives the CSI-RS. As described, such a CSI-RS may use fewer resources compared to those of a typical CSI-RS, due to the use of TR-CSI resource elements.

[0085] In operation S804, the method performs a coarse channel estimation.

[0086] In operation S806, the method receives TR-CSI resource elements.

[0087] In operation S808, the method reconstructs the TR-CSI resource elements. For example, the method may use the results of the coarse channel estimation to reconstruct the TR- CSI resource elements.

[0088] In operation S810, the method performs a fine channel estimation. As described, this fine channel estimation uses the CSI-RS as a reference signal, along with the TR-CSI resource elements.

[0089] In operation S830, the method concludes by establishing a downlink based on the fine channel estimation. Because the receiving apparatus has performed a fine channel estimation, it is able to receive information successfully, even though the CSI-RS requires fewer symbols than would otherwise be necessary.

[0090] FIG. 9 illustrates a block diagram of a transmission apparatus 900, according to some embodiments of the present disclosure. In FIG. 9, the transmitting device includes a TR-CSI data path and a CSI-RS generation module 940. The TR-CSI data path and the CSI-RS generation module 940 both provide information for resource mapping module 950.

[0091] In FIG. 9, there is a data transmission scheme including a TR-CSI data path. For example, the TR-CSI begins with an encoding module 902. Encoding involves converting the original data into an encoded form that is more suitable for transmission. A number of various encoding algorithms exist and may be used by the encoding module 902.

[0092] The encoding module 902 provides its results to a rate matching module 904. Rate matching involves matching the incoming bits to available resources. For example, there may be some resources available for data transmission over the resource grid including all the antennas, time, and subcarriers. The rate matching module 904 has the encoded bits which are required to transmit over those available resources after modulation. Rate matching module 904 rate matches these encoded bits to those available resources either by repeating a few of the encoded bits if they are fewer bits than resources or discarding a few of the encoded bits if they are more bits than resources.

[0093] The rate matching module 904 provides its results to interleaving module 906. With respect to interleaving, burst errors can be introduced in data during transmission. Interleaving provides a way to address burst errors. Interleaving module 906 spreads user bits in time so that useful information bits are not present in succession. Interleaving module 906 may be optional. For example, interleaving may introduce delays because de-interleaving cannot be performed until all interleaved data is received.

[0094] The interleaving module 906 provides its results to modulation module 908. Modulation is the method by which one or more parameters of a higher frequency carrier is varied by the actual signal containing user information. Modulation techniques can be analog or digital, but in the present embodiments, the modulation module 908 may use a digital modulation technique. For example, digital modulation may provide higher capacity, more information security, better utilization of resources, greater robustness, and better quality.

[0095] The modulation module 908 provides its results to add OCC module 910. Add OCC module 910 generates the OCC codes. As described above, orthogonal cover codes are length-2 Walsh codes extended over the two DMRS in the subframe. Walsh Code is a group of spreading codes having good autocorrelation properties and poor cross-correlation properties. Walsh codes are the backbone of CDMA systems and are used to develop the individual channels in CDMA. For Interim Standard IS-95, a common CDMA standard, there are 64 codes available. OCCs provide two benefits: they improve the reliability in separating the different RS from each other, especially when single-user MEMO (SU-MIMO) or multiple-user MEMO (MU-MIMO) transmission contains several transmission layers.

[0096] The add OCC module 910 provides its results to layer mapping module 912. Layer mapping is the process where each codeword is mapped to one or multiple layers.

[0097] The layer mapping module 912 provides its results to antenna port mapping module 920. Antenna port mapping module 920 takes the layer mapping and takes the next operation of performing a process where the layer data are allocated to multiple antenna ports. The antenna port mapping module 920 provides its results to resource mapping module 950.

[0098] Thus, FIG. 9 illustrates an embodiment. Some blocks, for example, interleaving module 906 or others, may or may not be present in various embodiments of a TR-CSI path. Based on the information presented in FIG. 9, the BS may determine a payload size, an MCS, a rank, and other information of the TR-CSI path according to the UE’s CSI feedback history. Such a payload size, an MCS, a rank, and other information of the TR-CSI path may be sent to UE in downlink control information (DCI) with a CSLRS configuration or a layer 3 (L3) message. OCC may be frequency direction OCC, time direction OCC, or a combination. The order of OCC may support the same number of antenna ports as that used by a CSI-RS.

[0099] A TR-CSI can send control information (including but not limited to DCI), a payload from medium access control (MAC), or both. Hybrid automatic repeat request (HARQ) may be supported in TR-CSI in some embodiments. The UE can acknowledge its reception of TR- CSI via using acknowledgment (ACK) feedback. The UE can also choose not to feedback ACK for it because the TR-CSI signal quality is very good.

[0100] If a beamforming is applied to CSI-RS, the same beamforming pattern is to be applied to TR-CSI. In various embodiments, TR-CSI can be coupled with either periodic or aperiodic CSI-RS.

[0101] In various embodiments, resource mapping may be flexible. For example, resource allocation of TR-CSI and CSI-RS may have different embodiments.

[0102] FIG. 10 is a diagram illustrating different types of TR-CSI and CSI-RS arrangements in transmitted data 1000, according to some embodiments. For example, FIG. 10 presents types of TR-CSI and CSI-RS arrangements SI 002.

[0103] One embodiment is where TR-CSI and CSI-RS are in different symbols S1002A. In a related embodiment, the first CSI-RS symbol is ahead of the first TR-CSI symbol S1002B. If there are a total of 3 TR-CSI and CSI-RS symbols in a slot, one example includes 1 CSI-RS followed by 2 TR-CSI symbols, and another example may be 1 CSI-RS symbol followed by 1 TR- CSI symbol and then followed by another CSI-RS symbol.

[0104] One embodiment is where TR-CSI and CSI-RS are sent in the same symbol but in different frequency resources, for example, different resource blocks S1002C. One example is where of K _t resource blocks have DMRS and M _t of K _t resource blocks have TR-CSI in symbol /, . K _t , N _t and M _t may be the same or be different in different symbols /, .

[0105] One embodiment is where in some symbols there are sent both TR-CSI and CSI- RS, but in some symbols, there is sent only TR-CSI S1002D. In the symbol /, with both TR-CSI and CSI-RS being sent, N _t oi K _t resource blocks have DMRS and of K _t resource blocks have TR-CSI in symbol /, . K _: . N _t and M _t may be the same or different in different symbols /, .

[0106] One embodiment is where in some symbols there are sent both TR-CSI and CSI- RS but in some symbol, there is only CSI-RS S1002E. In the symbol n _t with both TR-CSI and CSI-RS, N _t of K _t resource blocks have DMRS and M _t of K _t resource blocks have TR-CSI in symbol l _t . K _t , N _t and can be same or different in different symbol l _t . [0107] According to one aspect of the present disclosure, an apparatus including at least one processor and a memory storing instructions is disclosed. The instructions, when executed by the at least one processor, cause the apparatus to transmit a channel state information reference signal (CSI-RS) to a receiver. The instructions, when executed by the at least one processor, further cause the apparatus to encode traffic resource element for channel state information (TR-CSI) resource elements. The instructions, when executed by the at least one processor, further cause the apparatus to modulate the encoded TR-CSI resource elements. The instructions, when executed by the at least one processor, further cause the apparatus to transmit the modulated TR-CSI resource elements to the receiver over a TR-CSI path. The instructions, when executed by the at least one processor, further cause the apparatus to receive channel state information from the receiver based on the CSI-RS and the TR-CSI resource elements, as reconstructed by the receiver. [0108] In some embodiments, using the TR-CSI reduces overhead used for the CSI-RS.

[0109] In some embodiments, the apparatus determines at least one of payload size, modulation coding scheme (MCS), rank, and other information of the TR-CSI path according to a CSI feedback history of the receiver.

[0110] In some embodiments, at least one of payload size, modulation coding scheme

(MCS), rank, and other information of the TR-CSI path are sent with a CSI-RS configuration or a layer 3 (L3) message.

[OHl] In some embodiments, the apparatus adds orthogonal correcting codes (OCC).

[0112] In some embodiments, the OCC is frequency direction OCC, time direction OCC, or combination OCC.

[0113] In some embodiments, an order of OCC supports a same number of antenna ports as a number of antenna ports used by the CSI-RS.

[0114] In some embodiments, the TR-CSI path sends either or both of control information and a payload from medium access control (MAC).

[0115] In some embodiments, the TR-CSI path supports a hybrid automatic repeat request (HARQ).

[0116] In some embodiments, a beamforming is applied to the CSI-RS, and a same beamforming is applied to the TR-CSI path.

[0117] In some embodiments, symbols in the TR-CSI path and symbols in the CSI-RS are in different transmitted symbols.

[0118] In some embodiments, a first transmitted CSI-RS symbol is transmitted ahead of a first transmitted TR-CSI symbol in a slot.

[0119] In some embodiments, resource elements in the TR-CSI path and symbols in the CSI-RS are transmitted in a same symbol but are transmitted in different frequency resources. [0120] In some embodiments, in some transmitted resource blocks there are both resource elements of the TR-CSI resource elements and CSI-RS symbols, and in some transmitted resource blocks, there are only resource elements of the TR-CSI resource elements.

[0121] In some embodiments, in some transmitted resource blocks, there are both resource elements of the TR-CSI resource elements and CSI-RS symbols, and in some transmitted resource blocks, there are only CSI-RS symbols.

[0122] According to another aspect of the present disclosure, a method for wireless communication is disclosed. The method includes transmitting a channel state information reference signal (CSI-RS) to a receiver. The method further includes encoding traffic resource element for channel state information (TR-CSI) resource elements. The method further includes modulating the encoded TR-CSI resource elements. The method further includes transmitting the modulated TR-CSI resource elements to the receiver over a TR-CSI path. The method further includes receiving channel state information from the receiver based on the CSI-RS and the TR- CSI resource elements, as reconstructed by the receiver.

[0123] According to another aspect of the present disclosure, a baseband chip is disclosed. The baseband chip includes a channel state information reference signal transmission circuit. The channel state information reference signal transmission circuit is configured to transmit a channel state information reference signal (CSI-RS) to a receiver. The baseband chip further includes a traffic resource element for channel state information (TR-CSI) encoding circuit. The TR-CSI encoding circuit is configured to encode TR-CSI resource elements. The baseband chip further includes a TR-CSI modulating circuit. The TR-CSI modulating circuit is configured to modulate the TR-CSI resource elements. The baseband chip further includes a TR-CSI transmission circuit. The TR-CSI transmission circuit is configured to transmit the modulated TR-CSI resource elements to the receiver over a TR-CSI path using the first channel information to the receiver. The baseband chip further includes a channel state information circuit. The channel information circuit is configured to receive channel state information from the receiver based on the CSI-RS and the TR-CSI resource elements, as reconstructed by the receiver.

[0124] According to another aspect of the present disclosure, an apparatus for wireless communication including at least one processor and a memory storing instructions is disclosed. The instructions, when executed by the at least one processor, cause the apparatus to receive a channel state information reference signal (CSI-RS) from a transmitter. The instructions, when executed by the at least one processor, further cause the apparatus to estimate first channel information using the CSI-RS. The instructions, when executed by the at least one processor, further cause the apparatus to receive traffic resource element for channel state information (TR- CSI) resource elements from the transmitter using the first channel information over a TR-CSI path. The instructions, when executed by the at least one processor, further cause the apparatus to reconstruct the TR-CSI resource elements. The instructions, when executed by the at least one processor, cause the apparatus to estimate second channel information using the CSI-RS and the reconstructed TR-CSI resource elements.

[0125] In some embodiments, using the TR-CSI reduces overhead used for the CSI-RS.

[0126] In some embodiments, the apparatus uses a CSI feedback history to determine at least one of payload size, modulation coding scheme (MCS), rank, and other information of the TR-CSI path for the transmitter.

[0127] In some embodiments, at least one of payload size, modulation coding scheme (MCS), rank, and other information of the TR-CSI path are received with a CSI-RS configuration or a Layer 3 (L3) message.

[0128] In some embodiments, the apparatus receives either or both of control information and a payload from medium access control (MAC) with the TR-CSI resource elements.

[0129] In some embodiments, the TR-CSI path supports a hybrid automatic repeat request (HARQ).

[0130] In some embodiments, a beamforming is applied to the CSI-RS, and a same beamforming is applied to the TR-CSI path.

[0131] In some embodiments, symbols in the TR-CSI path and symbols in the CSI-RS are in different transmitted symbols.

[0132] In some embodiments, a first transmitted CSI-RS symbol is transmitted ahead of a first transmitted TR-CSI symbol in a slot.

[0133] In some embodiments, resource elements in the TR-CSI path and symbols in the CSI-RS are transmitted in a same symbol but are transmitted in different frequency resources.

[0134] In some embodiments, in some transmitted resource blocks there are both resource elements of the TR-CSI resource elements and CSI-RS symbols, and in some transmitted resource blocks there are only resource elements of the TR-CSI resource elements.

[0135] In some embodiments, in some transmitted resource blocks there are both resource elements of the TR-CSI resource elements and CSI-RS symbols, and in some transmitted resource blocks there are only CSI-RS symbols.

[0136] According to another aspect of the present disclosure, a method for wireless communication is disclosed. The method includes receiving a channel state information reference signal (CSI-RS) from a transmitter. The method further includes estimating first channel information using the CSI-RS. The method further includes receiving traffic resource element for channel state information (TR-CSI) resource elements from the transmitter using the first channel information over a TR-CSI path. The method further includes reconstructing the TR-CSI resource elements. The method further includes estimating second channel information using the CSI-RS and the reconstructed TR-CSI resource elements.

[0137] According to another aspect of the present disclosure, a baseband chip is disclosed. The baseband chip includes a channel state information reference signal (CSI-RS) receiving circuit. The CSI-RS receiving circuit is configured to receive a CSI-RS from a transmitter. The baseband chip further includes a first channel estimation circuit. The first channel estimation circuit is configured to estimate first channel information using the CSI-RS. The baseband chip further includes a traffic resource element for channel state information (TR-CSI) receiving circuit. The TR-CSI receiving circuit is configured to receive TR-CSI resource elements from the transmitter using the first channel information over a TR-CSI path. The baseband chip further includes a reconstruction circuit. The reconstruction circuit is configured to reconstruct the TR- CSI resource elements. The baseband chip further includes a second channel estimation circuit. The second channel estimation circuit is configured to estimate second channel information using the CSI-RS and the reconstructed TR-CSI resource elements.

[0138] A benefit of this technology is at least to significantly improve spectral efficiency in wireless communications by eliminating or reducing the overhead that would otherwise be required to send a CSI-RS. Based on various quality metrics of the data, data RE substitutes for all or part of a CSI-RS when using channel state information to optimize a downlink transmission format. Such channel state information is required for successful operation but can be performed without all or some of the CSI-RS when data RE of sufficient quality allows. Specifically, the data RE includes a TR-CSI data path that uses traffic information to provide CSI information and thereby substitute for portions of a CSI-RS.

[0139] Thus, this solution reduces or eliminates the wasted resources that would otherwise be occupied by CSI-RS and thereby increases spectral efficiency, such as in an OFDM or OFDMA communication system. Compared with the current 5G with CSI-RS in every resource block of 2 symbols per slot, embodiments can reduce CSI-RS to every 2 resource blocks of 1 symbol per slot. Thus, embodiments may achieve a resource savings of 75%.

[0140] The foregoing description of the specific embodiments will so reveal the general nature of the present disclosure that others can, by applying knowledge within the skill of the art, readily modify and/or adapt for various applications such specific embodiments, without undue experimentation, without departing from the general concept of the present disclosure. Therefore, such adaptations and modifications are intended to be within the meaning and range of equivalents of the disclosed embodiments, based on the teaching and guidance presented herein. It is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation, such that the terminology or phraseology of the present specification is to be interpreted by the skilled artisan in light of the teachings and guidance.

[0141] Embodiments of the present disclosure have been described above with the aid of functional building blocks illustrating the implementation of specified functions and relationships thereof. The boundaries of these functional building blocks have been arbitrarily defined herein for the convenience of the description. Alternate boundaries can be defined so long as the specified functions and relationships thereof are appropriately performed.

[0142] The Summary and Abstract sections may set forth one or more but not all embodiments of the present disclosure as contemplated by the inventor(s), and thus, are not intended to limit the present disclosure and the appended claims in any way.

[0143] Various functional blocks, modules, and steps are disclosed above. The particular arrangements provided are illustrative and without limitation. Accordingly, the functional blocks, modules, and steps may be re-ordered or combined in different ways than in the examples provided above. Likewise, certain embodiments include only a subset of the functional blocks, modules, and steps, and any such subset is permitted.

[0144] The breadth and scope of the present disclosure should not be limited by any of the above-described embodiments, but should be defined only in accordance with the following claims and their equivalents.