WO2022139871A1

WO2022139871A1 - Apparatus and method for demodulation reference signal in wireless communication systems

Info

Publication number: WO2022139871A1
Application number: PCT/US2021/034942
Authority: WO
Inventors: Jian Gu
Original assignee: Zeku, Inc.
Priority date: 2020-12-21
Filing date: 2021-05-28
Publication date: 2022-06-30

Abstract

Embodiments of an apparatus and method using a demodulation reference signal are disclosed. In an example, an apparatus transmits a demodulation reference signal (DMRS) to a receiver. The apparatus modulates traffic resource element with reduced spectral efficiency (TRRSE) resource elements using a modulation and coding scheme (MCS) operating at a first spectral efficiency. The apparatus transmits the modulated TRRSE resource elements to the receiver using a TRRSE data path. The apparatus modulates standard resource elements using an MCS operating at a second spectral efficiency. The apparatus transmits the modulated standard resource elements to the receiver using a standard data path. The first spectral efficiency is lower than the second spectral efficiency.

Description

APPARATUS AND METHOD FOR DEMODULATION REFERENCE SIGNAL IN WIRELESS COMMUNICATION SYSTEMS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority to U.S. Provisional Patent Application No. 63/128,799 filed December 21, 2020, entitled “METHOD FOR DEMODULATION REFERENCE SIGNAL,” 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 demodulation reference signal in wireless communication. Specifically, embodiments relate to an apparatus and method for using a demodulation 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 demodulation reference signal (DMRS) in an OFDM system are disclosed herein.

[0005] In one 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 transmit a demodulation reference signal (DMRS) to a receiver. The instructions, when executed by the at least one processor, further cause the apparatus to modulate traffic resource element with reduced spectral efficiency (TRRSE) resource elements using a modulation and coding scheme (MCS) operating at a first spectral efficiency. The instructions, when executed by the at least one processor, further cause the apparatus to transmit the modulated TRRSE resource elements to the receiver using a TRRSE data path. The instructions, when executed by the at least one processor, further cause the apparatus to modulate standard resource elements using an MCS operating at a second spectral efficiency. The instructions, when executed by the at least one processor, further cause the apparatus to transmit the modulated standard resource elements to the receiver using a standard data path. The first spectral efficiency is lower than the second spectral efficiency.

[0006] In another example, a method for wireless communication is disclosed. The method includes transmitting a demodulation reference signal (DMRS) to a receiver. The method further includes modulating traffic resource element with reduced spectral efficiency (TRRSE) resource elements using a modulation and coding scheme (MCS) operating at a first spectral efficiency. The method further includes transmitting the modulated TRRSE resource elements to the receiver using a TRRSE data path. The method further includes modulating standard resource elements using an MCS operating at a second spectral efficiency. The method further includes transmitting the modulated standard resource elements to the receiver using a standard data path. The first spectral efficiency is lower than the second spectral efficiency.

[0007] In another example, a baseband chip is disclosed. The baseband chip includes a demodulation reference signal (DMRS) transmission circuit. The DMRS transmission circuit is configured to transmit a DMRS to a receiver. The baseband chip further includes a traffic resource element with reduced spectral efficiency (TRRSE) modulation circuit. The TRRSE modulation circuit is configured to modulate TRRSE resource elements using a modulation and coding scheme (MCS) operating at a first spectral efficiency. The baseband chip further includes a TRRSE transmission circuit. The TRRSE transmission circuit is configured to transmit the modulated TRRSE resource elements to the receiver using a TRRSE data path. The baseband chip further includes a standard resource element modulation circuit. The standard resource element modulation circuit is configured to modulate standard resource elements using an MCS operating at a second spectral efficiency. The baseband chip further includes a standard resource element transmission circuit. The standard resource element transmission circuit is configured to transmit the modulated standard resource elements to the receiver using a standard data path. The first spectral efficiency is lower than the second spectral efficiency.

[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 demodulation reference signal (DMRS) from a transmitter. The instructions, when executed by the at least one processor, further cause the apparatus to estimate a first channel information using the DMRS. The instructions, when executed by the at least one processor, further cause the apparatus to receive traffic resource element with reduced spectral efficiency (TRRSE) resource elements from the transmitter using a TRRSE data path and the first channel information. The instructions, when executed by the at least one processor, further cause the apparatus to reconstruct the TRRSE resource elements. The instructions, when executed by the at least one processor, further cause the apparatus to estimate a second channel information using the TRRSE resource elements and the DMRS. The instructions, when executed by the at least one processor, further cause the apparatus to receive standard resource elements from the transmitter using a standard data path and the second channel information. The TRRSE resource elements are modulated by a modulation and coding scheme (MCS) operating at a first spectral efficiency, and the standard resource elements are modulated by an MCS operating at a second spectral efficiency. The first spectral efficiency is lower than the second spectral efficiency.

[0009] In another example, a method for wireless communication is disclosed. The method includes receiving a demodulation reference signal (DMRS) from a transmitter. The method further includes estimating a first channel information using the DMRS. The method further includes receiving traffic resource element with reduced spectral efficiency (TRRSE) resource elements from the transmitter using a TRRSE data path and the first channel information. The method further includes reconstructing the TRRSE resource elements. The method further includes estimating a second channel information using the TRRSE resource elements and the DMRS. The method further includes receiving standard resource elements from the transmitter using a standard data path and the second channel information. The TRRSE resource elements are modulated by a modulation and coding scheme (MCS) operating at a first spectral efficiency, and the standard resource elements are modulated by an MCS operating at a second spectral efficiency. The first spectral efficiency is lower than the second spectral efficiency.

[0010] In another example, a baseband chip is disclosed. The baseband chip includes a demodulation reference signal (DMRS) receiving circuit. The DMRS receiving circuit is configured to receive a DMRS from a transmitter. The baseband chip further includes a first channel estimation circuit. The first channel estimation circuit is configured to estimate a first channel information using the DMRS. The baseband chip further includes a traffic resource element with reduced spectral efficiency (TRRSE) receiving circuit. The TRRSE receiving circuit is configured to receive resource elements from the transmitter using a TRRSE data path and the first channel information. The baseband chip further includes a reconstruction circuit. The reconstruction circuit is configured to reconstruct the TRRSE resource elements. The baseband chip further includes a second channel estimation circuit. The second channel estimation circuit is configured to estimate a second channel information using the TRRSE resource elements and the DMRS. The baseband chip further includes a standard receiving circuit. The standard receiving circuit is configured to receive standard resource elements from the transmitter using a standard data path and the second estimated channel. The TRRSE resource elements are modulated by a modulation and coding scheme (MCS) operating at a first spectral efficiency, and the standard resource elements are modulated by an MCS operating at a second spectral efficiency. The first spectral efficiency is lower than the second spectral efficiency.

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] FIGS. 4A and 4B are block diagrams of transmission circuits where a TRRSE substitutes for part of a DMRS, according to some embodiments of the present disclosure.

[0016] FIG. 5 is a block diagram of receiving circuits where a TRRSE substitutes for part of a DMRS, according to some embodiments of the present disclosure.

[0017] FIG. 6 is a sequence diagram of a method where a TRRSE substitutes for part of a DMRS, according to some embodiments of the present disclosure.

[0018] FIG. 7 illustrates a flowchart of a transmission method where a TRRSE substitutes for part of a DMRS, according to some embodiments of the present disclosure.

[0019] FIG. 8 illustrates a flowchart of a reception method where a TRRSE substitutes for part of a DMRS, according to some embodiments of the present disclosure.

[0020] FIG. 9 illustrates a block diagram where a TRRSE substitutes for part of a DMRS, according to some embodiments of the present disclosure.

[0021] FIG. 10 illustrates a block diagram where a TRRSE substitutes for part of a DMRS, according to some embodiments of the present disclosure.

[0022] FIG. 11 illustrates a block diagram where a TRRSE substitutes for part of a DMRS, according to some embodiments of the present disclosure. [0023] FIG. 12 illustrates a block diagram where a TRRSE substitutes for part of a DMRS, according to some embodiments of the present disclosure.

[0024] FIG. 13 illustrates a block diagram where a TRRSE substitutes for part of a DMRS, according to some embodiments of the present disclosure.

[0025] FIG. 14 illustrates a block diagram where a TRRSE substitutes for part of a DMRS, according to some embodiments of the present disclosure.

[0026] FIG. 15 illustrates a block diagram of a communication device, according to some embodiments of the present disclosure.

[0027] Embodiments of the present disclosure will be described with reference to the accompanying drawings.

DETAILED DESCRIPTION

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] In an OFDM or OFDMA communication system, a reference signal is added to estimate channel properties, and the estimated channel is used to demodulate the signal. This reference signal is called a demodulation reference signal (DMRS).

[0035] A DMRS is added in 5G for different channels, including a physical downlink shared channel (PDSCH), a physical uplink shared channel (PUSCH), a physical downlink control channel (PDCCH), a physical uplink control channel (PUCCH), and a physical broadcast channel (PBCH). A DMRS is a known pseudo-random sequence initialized by different known parameters. In each resource block, there is a DMRS. Also, in each slot, DMRS is present in 1 or more DMRS symbols. At a higher Doppler value, a DMRS is sent in more symbols. Because a DMRS is used in downlink and uplink examples, it is also possible to improve how a DMRS is used in both such examples.

[0036] A DMRS is a predefined known sequence. A DMRS is overhead because it does not send information bits. Thus, the more resources a DMRS uses, the lower the spectral efficiency. 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 coding scheme (MCS), higher multiple-input and multiple-output (MIMO) rank, etc.

[0037] As discussed above, in an OFDM or an OFDMA communication system, a reference signal is added to estimate a channel, and the estimated channel is used to demodulate a signal. Such a reference signal is called a demodulation reference signal (DMRS). The present disclosure uses traffic resource elements (RE) with reduced spectral efficiency (TRRSE) to reduce resources otherwise occupied by the DMRS. Such an approach helps to improve spectral efficiency significantly, especially when a channel changes very slowly in a time and/or frequency direction. [0038] An important concept of the present disclosure is to replace part of DMRS resources with traffic RE sent at a format with lower spectral efficiency than otherwise scheduled. Such traffic RE are referred to as traffic RE with reduced spectral efficiency (TRRSE). At a receiver, coarse channel estimation is obtained with a DMRS, and then TRRSE can be received first. Received traffic REs with a lower spectral efficiency are used to reconstruct transmitted TRRSE. A fine channel estimation is obtained according to the DMRS and the reconstructed TRRSE, jointly.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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 (HER.) 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.

[0045] 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 UE) may generate the OFDMA symbol(s) and transmit the symbol to a receiving device (e.g., a BS). 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).

[0046] 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 receiving device. More detail regarding the possible implementation of a receiving device is provided by way of example in the description of a communications device 1500 in FIG. 15. Communications device 1500 may be configured as user equipment 102, access node 104, or core network element 106 in FIG. 1. Similarly, communications device 1500 may also be configured as computer 110, router 114, tablet 112, database 116, or authentication server 118 in FIG. 1. As shown in FIG. 15, communications device 1500 may include a processor 1502, a memory 1504, and a transceiver 1506. These components are shown as connected to one another by a bus, but other connection types are also permitted. When communications device 1500 is user equipment 102, additional components may also be included, such as a user interface (UI), sensors, and the like. Similarly, communications device 1500 may be implemented as a blade in a server system when communications device 1500 is configured as core network element 106. Other implementations are also possible, and these enumerated examples are not to be taken as limiting.

[0047] Transceiver 1506 may include any suitable device for sending and/or receiving data. Communications device 1500 may include one or more transceivers, although only one transceiver 1506 is shown for simplicity of illustration. An antenna 1508 is shown as a possible communication mechanism for communications device 1500. 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 1500 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 1500 as well.

[0048] As shown in FIG. 15, communications device 1500 may include processor 1502. Although only one processor is shown, it is understood that multiple processors can be included. Processor 1502 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 1502 may be a hardware device having one or more processing cores. Processor 1502 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. [0049] As shown in FIG. 15, communications device 1500 may also include memory 1504. Although only one memory is shown, it is understood that multiple memories can be included. Memory 1504 can broadly include both memory and storage. For example, memory 1504 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 1502. Broadly, memory 1504 may be embodied by any computer-readable medium, such as a non-transitory computer-readable medium.

[0050] Processor 1502, memory 1504, and transceiver 1506 may be implemented in various forms in communications device 1500 for performing wireless communication with DMRS and TRRSE functions. In some embodiments, processor 1502, memory 1504, and transceiver 1506 of communications device 1500 are implemented (e.g., integrated) on one or more system-on-chips (SoCs). In one example, processor 1502 and memory 1504 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 1502 and memory 1504 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 1502 and transceiver 1506 (and memory 1504 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 1508. 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.

[0051] Various aspects of the present disclosure related to DMRS and TRRSE approaches 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.

[0052] 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.

[0053] 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).

[0054] 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.

[0055] 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 MEMO 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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 MEMO 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- MEMO 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.

[0060] As discussed 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.

[0061] 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.

[0062] On the other hand, CSI acquisition is used for purposes such as determining the choice of transmission rank. Transmission rank refers to the number of layers or spatial streams transmitted simultaneously in MIMO, 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.

[0063] Thus, FIG. 2 and the above discussion provide background for typical reference signals in 5G NR. These typical reference signals are modified, as described further below, in examples to improve performance.

[0064] 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 UE that sends reference signals in a UL or implement a BS that receives reference signals in a UL. Alternatively, the apparatus provided in FIGS. 3 A 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 DMRS.

[0065] 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 an apparatus 300 including a host chip, an RF chip, and a baseband chip implementing a wireless communication system with DMRS management as presented in various figures in software and hardware, respectively, according to some embodiments of the present disclosure. Apparatus 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. 3A and 3B, apparatus 300 may include an RF chip 302, a baseband chip 304A in FIG. 3A 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 1502 and memory 1504, and RF chip 302 is implemented by processor 1502, memory 1504, and transceiver 1506, as described in greater detail with respect to FIG. 15. Besides on-chip memory 312 (also known as “internal memory,” e.g., as registers, buffers, or caches) on each chip 302, 304A or 304B, or 306, apparatus 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.

[0066] A DMRS may be sent in both an uplink from a UE to a BS and a downlink from a BS to a UE. Thus, the description presented directed towards one of these examples also applies to the other perspective, modified appropriately.

[0067] 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 perform the functions of the various modules 902 A, 904 A, 906 A, 908 A, 910, 912A, 914A, 916A, 902B, 904B, 906B, 908B, 912B, 914B, 916B, 940, and 950, as described further below, in detail, with respect to FIG. 9, and the related counterpart modules of FIGS. 10-14, as non-limiting examples. These modules produce a signal that uses a TRRSE data path in conjunction with a DMRS signal to provide information that allows a standard data path to convey information while allocating fewer resources to sending the DMRS signal. 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.

[0068] 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 sample- rate 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 304A or 304B then may receive and process the transmitted information based on the DMRS and TRRSE functions of modules of the various modules 902 A, 904 A, 906 A, 908 A, 910, 912A, 914A, 916A, 902B, 904B, 906B, 908B, 912B, 914B, 916B, 940, and 950, as described further below, in detail, with respect to FIG. 9, and the related counterpart modules of FIGS. 10-14, as non-limiting examples. The original data may be extracted by baseband chip 304A or 304B from the baseband signals and passed to host chip 306 through interface 314 or stored into system memory 308.

[0069] In some embodiments, the DMRS and TRRSE function schemes disclosed herein (e.g., by wireless communication system 900, 1000, 1100, 1200, 1300, or 1400) may be implemented in firmware and/or software by baseband chip 304A in FIG. 3A having a TRRSE module, which may include firmware and/or software, where the TRRSE module may be implemented and executed by a TRRSE processor, such as baseband processor 320 executing the stored instructions, as illustrated in FIG. 3 A. Baseband processor 320 may be a generic processor, such as a central processing unit or a digital signal processor (DSP), not dedicated to DMRS and TRRSE processing. That is, baseband processor 320 is also responsible for any other functions of baseband chip 304A and can be interrupted when performing DMRS and TRRSE approaches 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.

[0070] In some other embodiments, the DMRS and TRRSE approaches disclosed herein, for example, by wireless communication system 900, 1000, 1100, 1200, 1300, or 1400 may be implemented in hardware by baseband chip 304B in FIG. 3B having a dedicated TRRSE circuit 322 such as TRRSE circuit 322 as illustrated in FIG. 3B. TRRSE circuit 322 may include one or more integrated circuits (ICs), such as application-specific integrated circuits (ASICs), dedicated to implementing the DMRS and TRRSE approaches disclosed herein. Each element in wireless communication system 900, 1000, 1100, 1200, 1300, or 1400 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 TRRSE circuit 322. It is understood that in some examples, the DMRS and TRRSE approaches disclosed herein may be implemented in a hybrid manner, e.g., in both hardware and software. For example, some elements in wireless communication system 900, 1000, 1100, 1200, 1300, or 1400 may be implemented as a software module executed by baseband processor 320, while some elements in wireless communication system 900, 1000, 1100, 1200, 1300, or 1400 may be implemented as circuits.

[0071] FIGS. 4A and 4B are block diagrams of transmission circuits where a TRRSE substitutes for part of a DMRS 400. As noted, the transmission circuits may be part of a UE or a BS, as appropriate.

[0072] For example, FIG. 4A illustrates a DMRS transmission circuit 410, a TRRSE transmission circuit 420, and a standard resource element transmission circuit 450. These circuits include subunits that provide hardware to implement the TRRSE that substitutes for DMRS in FIGS. 9-14. Specifically, TRRSE transmission circuit 420 includes encoding circuit 422, rate matching circuit 424, interleaving circuit 426, modulating circuit 428, orthogonal cover code (OCC) circuit 430, layer mapping circuit 432, transform precoding circuit 434, and precoding circuit 436. Standard resource element transmission circuit 450 includes encoding circuit 452, rate matching circuit 454, interleaving circuit 456, modulating circuit 458, layer mapping circuit 460, transform precoding circuit 462, and precoding circuit 464. These constituent circuits correspond to the relevant modules of FIGS. 9-14 and illustrate how the functionality of FIGS. 9-14 may be implemented in portions of specialized hardware. Additional aspects of how these circuits function and operate are described further with respect to FIGS. 9-14, below.

[0073] FIG. 4B also illustrates a DMRS transmission circuit 410, a TRRSE transmission circuit 420, and a standard resource element transmission circuit 450. FIG. 4B is largely similar to FIG. 4A but is slightly different. Specifically, FIG. 4B lacks transform precoding circuit 434, precoding circuit 436, transform precoding circuit 462, and precoding circuit 464. In lieu of these elements, FIG. 4B includes antenna mapping circuit 440 in TRRSE transmission circuit 420 and antenna mapping circuit 470 in standard resource element transmission circuit.

[0074] FIG. 5 is a block diagram of receiving circuits where a TRRSE substitutes for part of a DMRS, according to some embodiments of the present disclosure. As noted, the receiving circuits may be part of a BS or a UE, as appropriate. Specifically, receiver 500 includes DMRS receiving circuit 510, coarse channel estimation circuit 512, TRRSE receiving circuit 514, reconstruction circuit 516, fine channel estimation circuit 518, and standard receiving circuit 520. These circuits correspond to related elements of the flowchart of FIG. 8. The operation of these circuits is described, further, at the corresponding discussion of FIG. 8.

[0075] FIG. 6 is a sequence diagram showing interactions between a base station (BS) and a user equipment (UE) in a TRRSE process 600, according to some embodiments of the present disclosure. FIG. 6 illustrates an embodiment in which a DMRS aids in a UL implementation. Thus, FIG. 6 shows an embodiment where the UE is the transmitter, and the BS is the receiver. However, in some other embodiments, a DMRS may also take the form of a DL implementation, and in such a counterpart implementation, the BS is the transmitter, and the UE is the receiver. Thus, a similar description applies, but with the roles and functions of the UE and the BS reversed.

[0076] Accordingly, in operation S602, the UE generates and transmits a DMRS. As discussed, the DMRS is a reference signal that aids in estimating a channel so that the channel may be used to demodulate a data signal. However, the sent DMRS uses fewer occupied resources because of the use of the TRRSE approach.

[0077] In operation S604, the UE generates and transmits a TRRSE signal. For example, ways of generating such a TRRSE signal are presented and explained further in FIGS. 9-14. In operation S606, the UE generates and transmits standard resource elements to the BS. For example, ways of generating such standard resource elements are presented and explained further in FIGS. 9-14.

[0078] In operation S608, the BS receives the DMRS from the UE. In operation S610, BS performs a coarse channel estimation based on the DMRS. The coarse channel estimation information is subsequently used by the BS to process the TRRSE signal.

[0079] In operation S612, the BS receives the TRRSE resource elements. As discussed, based on the way the TRRSE signal is formed, the TRRSE can be reconstructed even if fewer resources are used for the DMRS. Thus, in operation S614, the BS reconstructs the TRRSE, using the coarse channel estimation information. In operation S616, the reconstructed TRRSE is used to perform a fine channel estimation, together with DMRS. Accordingly, in operation S618, the BS receives the standard resource elements, which can be transmitted reliably based on the fine channel information provided by using the DMRS signal and the TRRSE signal.

[0080] It is to be noted that the interaction, above, has been characterized as being between a UE that generates the DMRS signal, the TRRSE signal, and the standard resource element signal, and a BS that receives such a signal. However, the reverse interaction, in which the BS sends such signals for receipt by a UE, is also possible in other embodiments.

[0081] FIG. 7 illustrates a flowchart of a method 700 for transmitting data in an OFDMA system, according to some embodiments of the present disclosure. As noted, the UE or the BS may be the transmitter, depending on whether a UL or a DL occurs.

[0082] In operation S702, the method transmits a DMRS. As described above, such a DMRS may use fewer resources than would otherwise be required because the TRRSE substitutes for some of the resources that would otherwise be used for a DMRS. Hence, the DMRS is only sufficient to obtain a coarse channel estimation rather than a fine channel estimation. [0083] In operation S704, the method modulates the TRRSE resource elements. Various aspects of such modulation are discussed further elsewhere in this disclosure. However, the modulation of the TRRSE resource elements has a relatively low spectral efficiency, which leads to the ability to use the TRRSE resource elements in channel estimation.

[0084] In operation S706, the method transmits TRRSE resource elements. As described above, the TRRSE resource elements substitute for portions of the DMRS that would otherwise be used for channel estimation. As a result, once the TRRSE resource elements are sent and received, the receiver is able to obtain a better fine channel estimation.

[0085] In operation S708, the method modulates the standard resource elements. However, the modulation of the standard resource elements has a relatively high spectral efficiency, which is possible because sufficient channel information is obtained from the TRRSE resource elements and the DMRS.

[0086] In operation S710, the method transmits standard resource elements. Based on the information from the TRRSE signal in combination and the DMRS, it is possible to provide a good channel estimation for such transmission without the full overhead that would otherwise be required for the DMRS.

[0087] In operation S720, the method concludes, in that the desired DMRS signal, TRRSE resource elements, and standard resource elements have all been transmitted.

[0088] FIG. 8 illustrates a flowchart of a reception method where a TRRSE substitutes for part of a DMRS 800, according to some embodiments of the present disclosure. As noted, the BS or the UE may be the receiver, depending on whether a UL or a DL occurs.

[0089] In operation S802, the method receives the DMRS.

[0090] In operation S804, the method performs a coarse channel estimation.

[0091] In operation S806, the method receives TRRSE resource elements.

[0092] In operation S808, the method reconstructs the TRRSE resource elements. For example, the method may use the coarse channel estimation to reconstruct the TRRSE resource elements.

[0093] In operation S810, the method performs a fine channel estimation. As described, this fine channel estimation uses the DMRS as a reference signal, along with the reconstructed TRRSE resource elements.

[0094] In operation S812, the method receives standard resource elements. Because the receiving apparatus has performed a fine channel estimation, it is able to receive these standard resource elements successfully, even though the DMRS requires fewer symbols than would otherwise be necessary. [0095] FIG. 9 illustrates a block diagram where a TRRSE substitutes for part of a DMRS, according to some embodiments of the present disclosure.

[0096] FIG. 9 shows an embodiment for the present disclosure. In FIG. 9, the transmitting device includes a TRRSE data path and a standard data path. These data paths both provide information for resource mapping module 950. In addition to the TRRSE data path and the standard data path, there is a DMRS generation module 940 that provides information for successfully demodulating signals.

[0097] In FIG. 9, there is a TRRSE data path. For example, the TRRSE begins with an encoding module 902A. 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 902A.

[0098] The encoding module 902A provides its results to a rate matching module 904A. 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 904A has the encoded bits which you need to transmit over those available resources after modulation. Rate matching module 904A 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.

[0099] The rate matching module 904A provides its results to interleaving module 906A. With respect to interleaving, burst errors can be introduced in data during transmission. Interleaving provides a way to address burst errors. Interleaving module 906A spreads user bits in time so that useful information bits are not present in succession. Interleaving module 906A may be optional. For example, interleaving may introduce delays because de-interleaving cannot be performed until all interleaved data is received.

[0100] The interleaving module 906A provides its results to modulation module 908A. Modulation is the method by which one or more parameters of a higher frequency carrier are varied by the actual signal containing user information. Modulation techniques can be analog or digital, but in the present embodiments, the modulation module 908A 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.

[0101] The modulation module 908 A provides its results to add OCC module 910. Add OCC module 01- generates the OCC codes. As described above, Orthogonal cover codes are length-2 Walsh codes extended over the two DMRS in the subframe. A Walsh code is a group of spreading codes having good autocorrel tion 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 MIMO (SU-MIMO) or multiple-user MIMO (MU-MIMO) transmission contains several transmission layers.

[0102] The add OCC module 910 provides its results to layer mapping module 912A. Layer mapping is the process where each codeword is mapped to one or multiple layers.

[0103] The layer mapping module 912A provides its results to transform precoding module 914A. Transform precoding is a first step to creating an OFDM wave by spreading UL data in a special way to reduce Peak-to-Average Power Ratio (PAPR) of the waveform. For example, transform precoding may involve a Digital Fourier Transform (DFT) operation.

[0104] The transform precoding module 914A provides its results to precoding module 916A. Precoding is the process where the layer data are allocated to multiple antenna ports. The precoding module 916A provides its results to resource mapping module 950.

[0105] In FIG. 9, the shared data path includes similar elements, with the exception that the shared data path does not include an add OCC module. Thus, the shared data path includes encoding module 902B, rate matching module 904B, interleaving module 906B, modulating module 908B, layer mapping module 912B, transform precoding module 914B, and precoding module 916B. The share data path also provides its results to resource mapping module 950.

[0106] In various embodiments, resource mapping may be flexible.

[0107] In one embodiment, TRRSE and DMRS are sent in different symbols. In such an embodiment, if the first DMRS symbol is put ahead of the first TRRSE symbol, it may save with respect to the receiver’s processing latency. If there are total of 3 TRRSE and DMRS symbols in a slot, one example is 1 DMRS symbol followed by 2 TRRSE symbols. Another example may be 1 DMRS symbol followed by 1 TRRSE symbol and then followed by another DMRS symbol. If there are total of 4 TRRSE and DMRS symbols in a slot, one example is 1 DMRS followed by 3 TRRSE symbols. Another example may be 1 DMRS symbol followed by 1 TRRSE symbol, and then followed by another DMRS symbol and then finally the last TRRSE symbol.

[0108] In another embodiment, TRRSE and DMRS are sent in the same symbol, but are in different frequency resources. For example, the TRRSE and the DMRS may be sent in different resource blocks. One example is where one of K_t resource blocks have DMRS, and the rest of the resource blocks have TRRSE in symbols n . K_t may be the same or different in different symbols n_t . A value of min 7 depends on a delay spread. [0109] Another embodiment is that in some symbols there is both TRRSE information and DMRS information, but in some symbols, there is only TRRSE information. In symbol n_t with both TRRSE information and DMRS information, one of K resource blocks has DMRS information and the rest of the resource blocks have TRRSE in the symbol. K_t can be the same or different in different symbols n_t . min K depending on delay spread. i

[0110] Yet another embodiment is that in some symbols, there is both TRRSE information and DMRS information, but in some symbols, there is only DMRS information. In symbol n_t with both TRRSE information and DMRS information, one of K_t resource blocks has DMRS information, and the rest of the resource blocks have TRRSE in the symbol. K, can be the same or different in different symbols n_: . min K depending on delay spread. i

[0111] Some blocks (e.g., Interleaving, add OCC, layer mapping, transform precoding or precoding or some of these) may be present in neither or either or both traffic data paths. In the embodiment of FIG. 9, encoder in TRRSE can be the same or different from that in a normal traffic data path. In some examples, both encoders can use low-density parity check (LDPC) encoding. In some examples, an encoder in TRRSE path uses Polar encoding, while an encoder in a standard data path uses LDPC encoding. A TRRSE path can also use the same or a different MCS from a standard data path. OCC (orthogonal cover code) may be added in TRRSE if DMRS supports more than 1 port. Here, OCC may be frequency direction OCC, time direction OCC, or their combination. The order of component carriers (CC) may support the same number of antenna ports used by DMRS. The number of layers in TRRSE data path may be the same or smaller than that in the standard data path.

[0112] FIG. 10 illustrates a block diagram where a TRRSE substitutes for part of a DMRS, according to some embodiments of the present disclosure. FIG. 10 shows an embodiment for the present disclosure. The elements of FIG. 10 are similar to those of FIG. 9, and thus the same overall discussion applies. Thus, FIG. 10 includes rate matching modules 1004A and 1004B, interleaving modules 1006A and 1006B, modulation modules 1008A and 1008B, add OCC module 1010, layer mapping modules 1012A and 1012B, transform precoding modules 1014A and 1014B, precoding modules 1016A and 1016B, DMRS generation module 1040, and resource mapping module 1050. FIG. 10 differs from FIG. 9 in that instead of having separate encoding modules 902 A and 902B for the TRRSE data path and the standard data path, in FIG. 10, a unified encoding module 1002 performs encoding for both data paths. Otherwise, FIG. 10 is generally similar to FIG. 9.

[0113] FIG. 11 illustrates a block diagram where a TRRSE substitutes for part of a DMRS, according to some embodiments of the present disclosure. The elements of FIG. 11 are similar to those of FIG. 9, and thus the same overall discussion applies. Thus, FIG. 11 includes encoding modules 1102A and 1102B, rate matching modules 1104A and 1104B, interleaving modules 1106A and 1106B, modulation modules 1108 A and 1108B, add OCC module 1110, layer mapping modules 1112A and 1112B, DMRS generation module 1140, and resource mapping module 1150. FIG. 11 differs from FIG. 9 in that instead of having transform precoding modules 914A and 914B and precoding modules 916A and 916B, FIG. 11 includes antenna port mapping modules 1120A and 1120B for the TRRSE data path and the standard data path. Otherwise, FIG. 11 is generally similar to FIG. 9.

[0114] FIG. 12 illustrates a block diagram where a TRRSE substitutes for part of a DMRS, according to some embodiments of the present disclosure. The elements of FIG. 12 are similar to those of FIG. 9, and thus the same overall discussion applies. Thus, FIG. 12 includes rate matching modules 1204 A and 1004B, interleaving modules 1206 A and 1206B, modulation modules 1208 A and 1208B, add OCC module 1210, layer mapping modules 1212A and 1212B, DMRS generation module 1240, and resource mapping module 1050. FIG. 12 differs from FIG. 9 in that instead of having separate encoding modules 902A and 902B for the TRRSE data path and the standard data path, in FIG. 12, a unified encoding module 1202 performs encoding for both data paths. Also, instead of having transform precoding modules 914A and 914B and precoding modules 916A and 916B, FIG. 12 includes antenna port mapping modules 1220 A and 1220B for the TRRSE data path and the standard data path. Otherwise, FIG. 12 is generally similar to FIG. 9.

[0115] FIG. 13 illustrates a block diagram where a TRRSE substitutes for part of a DMRS, according to some embodiments of the present disclosure. The elements of FIG. 13 are similar to those of FIG. 9, and thus the same overall discussion applies. Thus, FIG. 13 includes interleaving modules 1306A and 1306B, modulation modules 1308A and 1308B, add OCC module 1310, layer mapping modules 1312A and 1312B, transform precoding modules 1314A and 1314B, precoding modules 1316A and 1316B, DMRS generation module 1340, and resource mapping module 1350. FIG. 13 differs from FIG. 9 in that instead of having separate encoding modules 902 A and 902B for the TRRSE data path and the standard data path, in FIG. 13, a unified encoding module 1302 performs encoding for both data paths. Also, instead of having separate rate matching modules 904 A and 904B, FIG. 13 includes a unified rate matching module 1304 for the TRRSE data path and the standard data path. Otherwise, FIG. 13 is generally similar to FIG. 9.

[0116] FIG. 14 illustrates a block diagram where a TRRSE substitutes for part of a DMRS, according to some embodiments of the present disclosure. The elements of FIG. 14 are similar to those of FIG. 9, and thus the same overall discussion applies. Thus, FIG. 14 includes interleaving modules 1406A and 1406B, modulation modules 1408A and 1008B, add OCC module 1410, layer mapping modules 1412A and 1412B, DMRS generation module 1440, and resource mapping module 1450. FIG. 14 differs from FIG. 9 in that instead of having separate encoding modules 902 A and 902B for the TRRSE data path and the standard data path, in FIG. 14, a unified encoding module 1402 performs encoding for both data paths. Also, instead of having separate rate matching modules 904 A and 904B, FIG. 14 includes a unified rate matching module 1404 for the TRRSE data path and the standard data path. Also, instead of having transform precoding modules 914A and 914B and precoding modules 916A and 916B, FIG. 14 includes antenna port mapping modules 1420A and 1420B for the TRRSE data path and the standard data path. Otherwise, FIG. 14 is generally similar to FIG. 9.

[0117] According to one aspect of the present disclosure, in one 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 transmit a demodulation reference signal (DMRS) to a receiver. The instructions, when executed by the at least one processor, further cause the apparatus to modulate traffic resource element with reduced spectral efficiency (TRRSE) resource elements using a modulation and coding scheme (MCS) operating at a first spectral efficiency. The instructions, when executed by the at least one processor, further cause the apparatus to transmit the modulated TRRSE resource elements to the receiver using a TRRSE data path. The instructions, when executed by the at least one processor, further cause the apparatus to modulate standard resource elements using an MCS operating at a second spectral efficiency. The instructions, when executed by the at least one processor, further cause the apparatus to transmit the modulated standard resource elements to the receiver using a standard data path. The first spectral efficiency is lower than the second spectral efficiency.

[0118] In some embodiments, wherein the TRRSE data path and the standard data path use a same channel.

[0119] In some embodiments, the apparatus is part of an orthogonal frequency-division multiplexing (OFDM) or orthogonal frequency-division multiple access (OFDMA) communication system.

[0120] In some embodiments, the transmitting the TRRSE resource elements includes encoding the TRRSE resource elements and rate matching the TRRSE resource elements, modulating the TRRSE resource elements, and transmitting the modulated TRRSE resource elements to the receiver.

[0121] In some embodiments, the transmitting the standard resource elements includes encoding the standard resource elements and rate matching the standard resource elements. [0122] In some embodiments, either one or both of the transmitting the TRRSE resource elements and the transmitting the standard resource elements further includes interleaving.

[0123] In some embodiments, the transmitting the TRRSE resource elements further includes adding an orthogonal cover code (OCC), and the DMRS supports more than one port.

[0124] In some embodiments, the OCC is a frequency direction OCC, a time direction OCC, or a combination OCC.

[0125] In some embodiments, either one or both of the transmitting the TRRSE resource elements and the transmitting the standard resource elements further includes any one or any combination of any two or more of layer mapping, transform precoding, and precoding.

[0126] In some embodiments, either one or both of the transmitting the TRRSE resource elements and the transmitting the standard resource elements further includes antenna port mapping.

[0127] In some embodiments, an encoder used for the TRRSE resource elements is a same encoder as an encoder used for the standard resource elements.

[0128] In some embodiments, the encoder used for the TRRSE resource elements and the encoder for used for the standard resource elements each use low-density parity check (LDPC) encoding.

[0129] In some embodiments, an encoder used for the TRRSE resource elements is a different encoder from an encoder used for the standard resource elements.

[0130] In some embodiments, the encoder used for the TRRSE resource elements uses Polar encoding, and the encoder used for the standard resource elements uses LDPC encoding.

[0131] In some embodiments, the modulating the TRRSE resource elements and the modulating the standard resource elements each use a same MCS.

[0132] In some embodiments, the modulating the TRRSE resource elements and the modulating the standard resource elements each use a different MCS.

[0133] In some embodiments, a number of layers used for transmitting the TRRSE resource elements is a same or a smaller number than a number of layers used for transmitting the standard resource elements.

[0134] In some embodiments, an order of component carriers (CC) supports a same number of antenna ports as a number of antenna ports used by the DMRS.

[0135] According to another aspect of the present disclosure, a method for wireless communication is disclosed. The method includes transmitting a demodulation reference signal (DMRS) to a receiver. The method further includes modulating traffic resource element with reduced spectral efficiency (TRRSE) resource elements using a modulation and coding scheme (MCS) operating at a first spectral efficiency. The method further includes transmitting the modulated TRRSE resource elements to the receiver using a TRRSE data path. The method further includes modulating standard resource elements using an MCS operating at a second spectral efficiency. The method further includes transmitting the modulated standard resource elements to the receiver using a standard data path. The first spectral efficiency is lower than the second spectral efficiency.

[0136] According to another aspect of the present disclosure, a baseband chip is disclosed. The baseband chip includes a demodulation reference signal (DMRS) transmission circuit. The DMRS transmission circuit is configured to transmit a DMRS to a receiver. The baseband chip further includes a traffic resource element with reduced spectral efficiency (TRRSE) modulation circuit. The TRRSE modulation circuit is configured to modulate TRRSE resource elements using a modulation and coding scheme (MCS) operating at a first spectral efficiency. The baseband chip further includes a TRRSE transmission circuit. The TRRSE transmission circuit is configured to transmit the modulated TRRSE resource elements to the receiver using a TRRSE data path. The baseband chip further includes a standard resource element modulation circuit. The standard resource element modulation circuit is configured to modulate standard resource elements using an MCS operating at a second spectral efficiency. The baseband chip further includes a standard resource element transmission circuit. The standard resource element transmission circuit is configured to transmit the modulated standard resource elements to the receiver using a standard data path to the receiver. The first spectral efficiency is lower than the second spectral efficiency. [0137] 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 demodulation reference signal (DMRS) from a transmitter. The instructions, when executed by the at least one processor, further cause the apparatus to estimate a first channel information using the DMRS. The instructions, when executed by the at least one processor, further cause the apparatus to receive traffic resource element with reduced spectral efficiency (TRRSE) resource elements from the transmitter using a TRRSE data path and the first channel information. The instructions, when executed by the at least one processor, further cause the apparatus to reconstruct the TRRSE resource elements. The instructions, when executed by the at least one processor, further cause the apparatus to estimate a second channel information using the TRRSE resource elements and the DMRS. The instructions, when executed by the at least one processor, further cause the apparatus to receive standard resource elements from the transmitter using a standard data path and the second channel information. The TRRSE resource elements are modulated by a modulation and coding scheme (MCS) operating at a first spectral efficiency, and the standard resource elements are modulated by an MCS operating at a second spectral efficiency. The first spectral efficiency is lower than the second spectral efficiency.

[0138] In some embodiments, wherein the TRRSE data path and the standard data path use a same channel.

[0139] In some embodiments, the apparatus is part of an orthogonal frequency-division multiplexing (OFDM) or orthogonal frequency-division multiple access (OFDMA) communication system.

[0140] In some embodiments, an encoder used for the TRRSE resource elements is a same encoder as an encoder used for the standard resource elements.

[0141] In some embodiments, the encoder used for the TRRSE resource elements and the encoder used for the standard resource elements each use low-density parity check (LDPC) encoding.

[0142] In some embodiments, an encoder used for the TRRSE resource elements is a different encoder from an encoder used for the standard resource elements.

[0143] In some embodiments, the encoder used for the TRRSE resource elements uses Polar encoding, and the encoder used for the standard resource elements uses LDPC encoding.

[0144] In some embodiments, the TRRSE resource elements and the standard resource elements are each modulated by a same MCS.

[0145] In some embodiments, the TRRSE resource elements and the standard resource elements are each modulated by a different MCS.

[0146] In some embodiments, a number of layers used for transmitting the TRRSE resource elements is a same or a smaller number than a number of layers used for transmitting the standard resource elements.

[0147] In some embodiments, an order of component carriers (CC) supports a same number of antenna ports as a number of antenna ports used by the DMRS.

[0148] According to another aspect of the present disclosure, a method for wireless communication is disclosed. The method includes receiving a demodulation reference signal (DMRS) from a transmitter. The method further includes estimating a first channel information using the DMRS. The method further includes receiving traffic resource element with reduced spectral efficiency (TRRSE) resource elements from the transmitter using a TRRSE data path and the first channel information. The method further includes reconstructing the TRRSE resource elements. The method further includes estimating a second channel information using the TRRSE resource elements and the DMRS. The method further includes receiving standard resource elements from the transmitter using a standard data path and the second channel information. The TRRSE resource elements are modulated by a modulation and coding scheme (MCS) operating at a first spectral efficiency, and the standard resource elements are modulated by an MCS operating at a second spectral efficiency. The first spectral efficiency is lower than the second spectral efficiency.

[0149] According to another aspect of the present disclosure, a baseband chip is disclosed. The baseband chip includes a demodulation reference signal (DMRS) receiving circuit. The DMRS receiving circuit is configured to receive a DMRS from a transmitter. The baseband chip further includes a first channel estimation circuit. The first channel estimation circuit is configured to estimate a first channel information using the DMRS. The baseband chip further includes a traffic resource element with reduced spectral efficiency (TRRSE) receiving circuit. The TRRSE receiving circuit is configured to receive resource elements from the transmitter using a TRRSE data path and the first channel information. The baseband chip further includes a reconstruction circuit. The reconstruction circuit is configured to reconstruct the TRRSE resource elements. The baseband chip further includes a second channel estimation circuit. The second channel estimation circuit is configured to estimate a second channel information using the TRRSE resource elements and the DMRS. The baseband chip further includes a standard receiving circuit. The standard receiving circuit is configured to receive standard resource elements from the transmitter using a standard data path and the second estimated channel. The TRRSE resource elements are modulated by a modulation and coding scheme (MCS) operating at a first spectral efficiency, and the standard resource elements are modulated by an MCS operating at a second spectral efficiency. The first spectral efficiency is lower than the second spectral efficiency.

[0150] A benefit of this technology is, at least, to significantly improve receiver performance by eliminating or reducing the overhead that would otherwise be required to send a DMRS. This solution reduces or eliminates the wasted resources that would otherwise be occupied by a DMRS and thereby increases spectral efficiency, such as in an OFDM or OFDMA communication system. For example, embodiments help improve spectral efficiency significantly, especially when a channel changes very slowly in a time and/or frequency direction.

[0151] For example, compared with the current 5G with PDSCH DMRS in every resource block of 4 symbols per slot, the present disclosure may reduce a DMRS to every K resource blocks of 1 symbol per slot. There may be a resource savings of 4K/(4K + 1). For example, with K=5, then the savings may be about 95%.

[0152] 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.

[0153] 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.

[0154] 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.

[0155] 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.

[0156] 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.

Claims

WHAT IS CLAIMED IS:

1. An apparatus for wireless communication, comprising: at least one processor; and a memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: transmit a demodulation reference signal (DMRS) to a receiver; modulate traffic resource element with reduced spectral efficiency (TRRSE) resource elements using a modulation and coding scheme (MCS) operating at a first spectral efficiency; transmit the modulated TRRSE resource elements to the receiver using a TRRSE data path; modulate standard resource elements using an MCS operating at a second spectral efficiency; and transmit the modulated standard resource elements to the receiver using a standard data path, wherein the first spectral efficiency is lower than the second spectral efficiency.

2. The apparatus of claim 1, wherein the TRRSE data path and the standard data path use a same channel.

3. The apparatus of claim 1, wherein the apparatus is part of an orthogonal frequencydivision multiplexing (OFDM) or orthogonal frequency-division multiple access (OFDMA) communication system.

4. The apparatus of claim 1, wherein the transmitting the TRRSE resource elements comprises: encoding the TRRSE resource elements; and rate matching the TRRSE resource elements.

5. The apparatus of claim 1, wherein the transmitting the standard resource elements comprises: encoding the standard resource elements; and rate matching the standard resource elements.

6. The apparatus of claim 1, wherein either one or both of the transmitting the TRRSE resource elements and the transmitting the standard resource elements further comprises interleaving.

7. The apparatus of claim 1, wherein the transmitting the TRRSE resource elements further comprises adding an orthogonal cover code (OCC), and the DMRS supports more than one port.

8. The apparatus of claim 7, wherein the OCC is a frequency direction OCC, a time direction OCC, or a combination OCC.

9. The apparatus of claim 1, wherein either one or both of the transmitting the TRRSE resource elements and the transmitting the standard resource elements further comprises any one or any combination of any two or more of layer mapping, transform precoding, and precoding.

10. The apparatus of claim 1, wherein either one or both of the transmitting the TRRSE resource elements and the transmitting the standard resource elements further comprises antenna port mapping.

11. The apparatus of claim 1, wherein an encoder used for the TRRSE resource elements is a same encoder as an encoder used for the standard resource elements.

12. The apparatus of claim 11, wherein the encoder used for the TRRSE resource elements and the encoder used for the standard resource elements each use low-density parity check (LDPC) encoding.

13. The apparatus of claim 1, wherein an encoder used for the TRRSE resource elements is a different encoder from an encoder used for the standard resource elements.

14. The apparatus of claim 13, wherein the encoder used for the TRRSE resource elements uses Polar encoding, and the encoder used for the standard resource elements uses LDPC encoding.

15. The apparatus of claim 1, wherein the modulating the TRRSE resource elements and the modulating the standard resource elements each use a same MCS.

16. The apparatus of claim 1, wherein the modulating the TRRSE resource elements and the modulating the standard resource elements each use a different MCS.

17. The apparatus of claim 1, wherein a number of layers used for transmitting the TRRSE resource elements is a same or a smaller number than a number of layers used for transmitting the standard resource elements.

18. The apparatus of claim 1, wherein an order of component carriers (CC) supports a same number of antenna ports as a number of antenna ports used by the DMRS.

19. A method for wireless communication, comprising: transmitting a demodulation reference signal (DMRS) to a receiver; modulating traffic resource element with reduced spectral efficiency (TRRSE) resource elements using a modulation and coding scheme (MCS) operating at a first spectral efficiency; transmitting the modulated TRRSE resource elements to the receiver using a TRRSE data path; modulating standard resource elements using an MCS operating at a second spectral efficiency; and transmitting the modulated standard resource elements to the receiver using a standard data path, wherein the first spectral efficiency is lower than the second spectral efficiency.

20. A baseband chip, comprising: a demodulation reference signal (DMRS) transmission circuit configured to transmit a DMRS to a receiver; a traffic resource element with reduced spectral efficiency (TRRSE) modulation circuit configured to modulate TRRSE resource elements using a modulation and coding scheme (MCS) operating at a first spectral efficiency; a TRRSE transmission circuit configured to transmit the modulated TRRSE resource elements to the receiver using a TRRSE data path; a standard resource element modulation circuit configured to modulate standard resource elements using an MCS operating at a second spectral efficiency; and a standard resource element transmission circuit configured to transmit the modulated standard resource elements to the receiver using a standard data path, wherein the first spectral efficiency is lower than the second spectral efficiency.

21. An apparatus for wireless communication, comprising: at least one processor; and a memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: receive a demodulation reference signal (DMRS) from a transmitter; estimate a first channel information using the DMRS; receive traffic resource element with reduced spectral efficiency (TRRSE) resource elements from the transmitter using a TRRSE data path and the first channel information; reconstruct the TRRSE resource elements; estimate a second channel information using the TRRSE resource elements and the DMRS; and receive standard resource elements from the transmitter using a standard data path and the second channel information, wherein the TRRSE resource elements are modulated by a modulation and coding scheme (MCS) operating at a first spectral efficiency and the standard resource elements are modulated by an MCS operating at a second spectral efficiency, and wherein the first spectral efficiency is lower than the second spectral efficiency.

22. The apparatus of claim 21, wherein the TRRSE data path and the standard data path use a same channel.

23. The apparatus of claim 21, wherein the apparatus is part of an orthogonal frequency-division multiplexing (OFDM) or orthogonal frequency-division multiple access (OFDM A) communication system.

24. The apparatus of claim 21, wherein an encoder used for the TRRSE resource elements is a same encoder as an encoder used for the standard resource elements.

25. The apparatus of claim 24, wherein the encoder used for the TRRSE resource elements and the encoder for used for the standard resource elements each use low-density parity check (LDPC) encoding.

26. The apparatus of claim 21, wherein an encoder used for the TRRSE resource elements is a different encoder from an encoder used for the standard resource elements.

27. The apparatus of claim 26, wherein the encoder used for the TRRSE resource elements uses Polar encoding, and the encoder used for the standard resource elements uses LDPC encoding.

28. The apparatus of claim 21, wherein the TRRSE resource elements and the standard resource elements are each modulated by a same MCS.

29. The apparatus of claim 21, wherein the TRRSE resource elements and the standard resource elements are each modulated by a different MCS.

30. The apparatus of claim 21, wherein a number of layers used for transmitting the TRRSE resource elements is a same or a smaller number than a number of layers used for transmitting the standard resource elements.

31. The apparatus of claim 21, wherein an order of component carriers (CC) supports a same number of antenna ports as a number of antenna ports used by the DMRS.

32. A method for wireless communication, comprising: receiving a demodulation reference signal (DMRS) from a transmitter; estimating a first channel information using the DMRS; receiving traffic resource element with reduced spectral efficiency (TRRSE) resource elements from the transmitter using a TRRSE data path and the first channel information; reconstructing the TRRSE resource elements; estimating a second channel information using the TRRSE resource elements and the DMRS; and receiving standard resource elements from the transmitter using a standard data path and the second channel information, wherein the TRRSE resource elements are modulated by a modulation and coding scheme (MCS) operating at a first spectral efficiency and the standard resource elements are modulated by an MCS operating at a second spectral efficiency, and wherein the first spectral efficiency is lower than the second spectral efficiency.

33. A baseband chip, comprising: a demodulation reference signal (DMRS) receiving circuit configured to receive a DMRS from a transmitter; a first channel estimation circuit configured to estimate a first channel information using the DMRS; a traffic resource element with reduced spectral efficiency (TRRSE) receiving circuit configured to receive TRRSE resource elements from the transmitter using a TRRSE data path and the first channel information; a reconstruction circuit configured to reconstruct the TRRSE resource elements; a second channel estimation circuit configured to estimate a second channel information using the TRRSE resource elements and the DMRS; and a standard receiving circuit configured to receive standard resource elements from the transmitter using a standard data path and the second channel information, wherein the TRRSE resource elements are modulated by a modulation and coding scheme

(MCS) operating at a first spectral efficiency and the standard resource elements are modulated by an MCS operating at a second spectral efficiency, and wherein the first spectral efficiency is lower than the second spectral efficiency.