WO2022139870A1

WO2022139870A1 - Method and apparatus for receiving data in orthogonal frequency division multiplexing system with iterative correction

Info

Publication number: WO2022139870A1
Application number: PCT/US2021/034936
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 for iterative correction in wireless communication are disclosed. In an example, a reference signal and an initial data signal are received by an apparatus. The apparatus performs initial channel estimation and interference and noise estimation and initially demodulates the initial data signal. The apparatus then iteratively produces a hard decision, regenerates a regenerated data signal, calculates interference and noise covariance, and obtains a corrected demodulated data signal until a quality is satisfied or a number of iterations have occurred. The apparatus further decodes the demodulated data signal.

Description

METHOD AND APPARATUS FOR RECEIVING DATA IN ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING SYSTEM WITH ITERATIVE CORRECTION

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of priority to U.S. Provisional Patent Application No. 63/128,779 filed December 21, 2020, entitled “METHOD FOR RECEIVING DATA IN OFDMA SYSTEM,” which is hereby incorporated by reference in its entirety.

BACKGROUND

[0002] Embodiments of the present disclosure relate to a method and apparatus for receiving data in wireless communication.

[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).

[0004] 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.

SUMMARY

[0005] Embodiments of an apparatus and method for receiving data in an OFDM or OFDMA system with iterative correction are disclosed herein.

[0006] In one example, an apparatus including at least one processor and a memory storing instructions is disclosed. The instructions, when executed by the at least one processor, cause the apparatus to receive a reference signal and an initial data signal, perform channel estimation and first interference and noise estimation based on the reference signal, initially demodulate the initial data signal to initialize a demodulated data signal based on the channel estimation and first interference and noise estimation, perform the following in an iterative manner, until a number of iterations reaches a maximum number or a quality of the demodulated data signal satisfies a condition: produce a hard decision of the demodulated data signal, regenerate a regenerated data signal based on the channel estimation and the hard decision, calculate interference and noise covariance based on second interference and noise estimation derived by subtracting the regenerated data signal from the initial data signal, and obtain a corrected demodulated data signal by demodulating the initial data signal based on the calculated interference and noise covariance, and decode the demodulated data signal.

[0007] In another example, a method for wireless communication is disclosed. The method includes receiving a reference signal and an initial data signal, performing channel estimation and first interference and noise estimation based on the reference signal, initially demodulating the initial data signal to initialize a demodulated data signal based on the channel estimation and first interference and noise estimation, performing the following in an iterative manner, until a number of iterations reaches a maximum number or a quality of the demodulated data signal satisfies a condition: producing a hard decision of the demodulated data signal, regenerating a regenerated data signal based on the channel estimation and the hard decision, calculating interference and noise covariance based on second interference and noise estimation derived by subtracting the regenerated data signal from the initial data signal, and obtaining a corrected demodulated data signal by demodulating the initial data signal based on the calculated interference and noise covariance, and decoding the demodulated data signal.

[0008] In still another example, a baseband chip includes an interface configured to receive a reference signal and an initial data signal, a channel estimation circuit configured to perform channel estimation and first interference and noise estimation based on the reference signal, a demodulation circuit configured to initially demodulate the initial data signal to initialize a demodulated data signal based on the channel estimation and first interference and noise estimation, an iterative correction circuit, configured to perform the following in an iterative manner, until a number of iterations reaches a maximum number or a quality of the demodulated data signal satisfies a condition: produce a hard decision of the demodulated data signal, regenerate a regenerated data signal based on the channel estimation and the hard decision, calculate interference and noise covariance based on second interference and noise estimation derived by subtracting the regenerated data signal from the initial data signal, and obtain a corrected demodulated data signal by demodulating the initial data signal based on the calculated interference and noise covariance, and a decoder circuit configured to decode the demodulated data signal.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] 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.

[0010] FIG. 1 illustrates a wireless network, according to some embodiments of the present disclosure.

[0011] FIG. 2 illustrates a detailed block diagram of a wireless communication process, in which a reference signal and a data signal are used to decode the data signal, according to some embodiments of the present disclosure.

[0012] FIG. 3 illustrates a detailed block diagram of a wireless communication process, in which a reference signal and a data signal are used to decode the data signal, according to some embodiments of the present disclosure.

[0013] FIG. 4 illustrates a detailed block diagram of a wireless communication process, in which a reference signal and a data signal are used to decode the data signal, according to some embodiments of the present disclosure.

[0014] FIG. 5 illustrates a detailed timing of a wireless communication process, in which a reference signal and a data signal are used to decode the data signal, according to some embodiments of the present disclosure.

[0015] FIG. 6 illustrates a detailed timing of a wireless communication process, in which a reference signal and a data signal are used to decode the data signal, according to some embodiments of the present disclosure.

[0016] FIGS. 7 A and 7B 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.

[0017] FIG. 8 illustrates a flowchart of a method for receiving data in an OFDM or OFDMA system, according to some embodiments of the present disclosure.

[0018] FIG. 9 illustrates a flowchart of another method for receiving data in an OFDM or OFDMA system, according to some embodiments of the present disclosure.

[0019] FIG. 10 illustrates a flowchart of still another method for receiving data in an OFDM or OFDMA system, according to some embodiments of the present disclosure.

[0020] FIG. 11 illustrates a flowchart of yet another method for receiving data in an OFDM or OFDMA system, according to some embodiments of the present disclosure.

[0021] FIG. 12 illustrates a block diagram of a receiving device, according to some embodiments of the present disclosure.

[0022] Embodiments of the present disclosure will be described with reference to the accompanying drawings. DETAILED DESCRIPTION

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] The techniques described herein are principally described in the context of the operation of an orthogonal frequency division multiple (OFDM) or 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, singlecarrier 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 WIFI 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.

[0028] Interference and noise fluctuate considerably in time and frequency directions in a wireless communication system. Accurate interference and noise estimation is important to successful performance. Typical approaches provide a simple way to perform interference and noise estimation by basing these estimates on a reference signal. However, information about interference and noise may also be available from a data signal. Typical approaches do not take advantage of such potential information. Thus, typical approaches have performance that suffers under certain conditions where interference and noise are particularly problematic.

[0029] Typical approaches to decoding a data signal use a reference signal to estimate interference and noise. First, channel estimation is done according to a received reference signal. Interference and noise on reference signal are obtained by subtracting the estimation channel from the received reference signal. Then, approaches apply a filter to get the estimated interference and noise covariance. The smallest resource granularity is a resource unit in WI-FI and a resource block in 4G and 5G. However, such a resource unit is too small for optimal results. Usually, filtering is applied to a cross-resource unit in WI-FI or a resource block in 4G and 5G. Typical approaches then simply use the interference and noise covariance for the data signal.

[0030] Although the typical solution is simple, it has poor performance, especially when any one or more of the following conditions is satisfied: 1) Interference and noise covariance is different in different resource blocks in 4G and 5G and resource units in WI-FI; 2) Interference and noise covariance on a reference signal is different from that on a data signal; and 3) The resource allocated for a given user is narrow, for example, just 1 resource block in 4G/5G or 1 resource unit in WI-FI.

[0031] In actual use cases, the above conditions 1) and 2) are always true. Condition 3) is very common for small packet applications, for example, VoIP, and so on.

[0032] In a downlink (DL) of an OFDM or OFDMA system such as 4G, 5G, and WI-FI, noise comes from thermal noise, and DL interference comes from other base stations (called eNode B in 4G or gNode-B in 5G or access point in WI-FI). Most of the time, not all resource blocks or resource units are used. Because of vacant resource blocks or units, DL interference and noise fluctuate considerably in time and frequency directions.

[0033] In an uplink (UL) of an OFDMA system such as 4G, 5G, and WI-FI, noise comes from thermal noise and interference comes from different terminals (called user equipment (UE) in 4G and 5G and called a terminal in WI-FI). Because different interfering terminals have different transmission powers, distances between a base station and interfering terminals are different, and resource allocations in different base stations are different, the interference and noise on different resource blocks are naturally different.

[0034] In 5G DL, a Physical Downlink Control Channel (PDCCH) can be transmitted in about 1 to 3 symbols. A Physical Downlink Shared Chanel (PDSCH) can be transmitted with precoding beamforming in any number of resource blocks. PDCCH uses a different precoding matrix. For example, the desired PDSCH data symbol can collide with a PDSCH data symbol, a PDCCH symbol, or no signal from an interfering base station. Because of this phenomenon, interference and noise on a PDSCH Demodulation Reference Signal (DMRS) can be different from that on a PDSCH Data Signal.

[0035] In LTE DL, a cell-specific reference signal (CRS) always exists, but a data resource element (RE) may be occupied or vacant. Therefore, the interference and noise power on a CRS is always larger or equal to that on a data RE.

[0036] When the resource allocated for a given user is narrow, the interference and noise estimation based on reference signal is not accurate, because the number of reference signal samples is too small. For example, 1 resource block (RB) is assigned, a 1-symbol type 1 DMRS is used, then the power in covariance matrix has a standard deviation of 3.9dB. Such an approach can cause significant performance degradation. As discussed in further detail below, embodiments provide ways of managing these issues.

[0037] FIG. 1 illustrates a wireless network 100, in which some or all 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. [0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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 may generate the OFDMA symbol(s) and transmit the symbol to a receiving device (e.g., a UE). When the receiving device receives the symbol(s), the receiver may perform the methods described in the present disclosure to use both a reference signal and a data signal to improve the ability of the receiver to successfully receive the symbol(s).

[0043] 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 receiving device 1200 in FIG. 12. Receiving device 1200 may be configured as user equipment 102, access node 104, or core network element 106 in FIG. 1. Similarly, receiving device 1200 may also be configured as computer 110, router 114, tablet 112, database 116, or authentication server 118 in FIG. 1. As shown in FIG. 12, receiving device 1200 may include a processor 1202, a memory 1204, and a transceiver 1206. These components are shown as connected to one another by a bus, but other connection types are also permitted. When receiving device 1200 is user equipment 102, additional components may also be included, such as a user interface (UI), sensors, and the like. Similarly, receiving device 1200 may be implemented as a blade in a server system when receiving device 1200 is configured as core network element 106. Other implementations are also possible, and these enumerated examples are not to be taken as limiting.

[0044] Transceiver 1206 may include any suitable device for sending and/or receiving data. Receiving device 1200 may include one or more transceivers, although only one transceiver 1206 is shown for simplicity of illustration. An antenna 1208 is shown as a possible communication mechanism for receiving device 1200. If the communication is MIMO, multiple antennas and/or arrays of antennas may be utilized for such communication. Additionally, examples of receiving device 1200 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 receiving device 1200 as well.

[0045] FIG. 2 illustrates a detailed block diagram of a wireless communication process in a wireless communication system 200, in which a reference signal and a data signal are used to decode the data signal, according to a typical art. According to such a process, a reference signal is an input for channel estimation module 210 and noise estimation module 220. The result of the channel estimation module 210 is provided for use in the noise estimation module 220. Then, the results of the channel estimation module 210, the noise estimation module 220, and the data signal are all used to perform demodulation by demodulation module 230. Finally, the demodulation module 230 provides its results to the decoder module 240, which produces an output signal representing the decoded data signal. However, as discussed above, this simplistic approach can cause significant performance degradation. More particularly, in the example of FIG. 2, the channel and noise estimation is performed solely based on the reference signal. However, characteristics of the data signal also provide information about noise characteristics, and hence, the present embodiments provide ways to use such information to provide better interference and noise estimation.

[0046] FIG. 3 illustrates a detailed block diagram of a wireless communication process in a wireless communication system 300, in which a reference signal and a data signal are used to estimate noise, according to some embodiments of the present disclosure.

[0047] According to FIG. 3, other processes occur in which both a reference signal and a data signal are used to estimate noise, according to an embodiment. In particular, FIG. 3 shows a first process that uses an iterative approach to improve the handling of noise. For example, in FIG. 3, the reference signal is provided for channel estimation module 310 and first noise estimation module 320. First noise estimation module 320 provides an initial noise estimation based on the results of the channel estimation module 310. The results of first noise estimation module 320 are provided to noise filter module 330, for refinement using an iterative process. Noise filter module 330 provides its output for demodulation module 340, which bases its demodulation results on the results of noise filter module 330, the result of channel estimation module 310, and an initial received data signal.

[0048] The demodulation module 340 checks whether a sufficient quality for the data signal has been obtained or if a maximum number of iterations have been performed. If so, the demodulation module 340 provides the current data signal to the decoder module 350 for decoding to produce an output. However, if the sufficient quality for the data signal has not yet been obtained and the maximum number of iterations have not yet been performed, the demodulation module 340 provides its results to second noise estimation module 360, which iterates the current data signal through another noise filter module 330 processing followed by another demodulation module 340 processing, which again checks the quality of the data signal and checks to see if a maximum number of iterations have been performed.

[0049] Each of the modules in FIG. 3 may be implemented as a software module, such as software code or software instructions implemented by a processor. Such software code or software instructions may be stored in a memory. For example, in the embodiment of FIG. 12, processor 1202 may execute instructions stored in memory 1204 to implement the modules presented in FIG. 3. Alternatively, each module can be implemented a hardware module implemented, such as by integrated circuits, for example, application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), and so on, as non-limiting examples. For example, in the embodiments of FIGS. 7A and 7B, the modules in FIG. 3 may be implemented using such hardware modules in the context of apparatus 700. For example, the modules may be implemented as dedicated circuits within appropriate portions of apparatus 700, such as by dedicated circuits within baseband chip 704A in FIG. 7A or baseband chip 704B in FIG. 7B.

[0050] The process presented in FIG. 3 is described in greater detail with respect to flowcharts FIGS. 8-11, below, in particular at FIG. 8. Thus, FIG. 3 shows an approach in which the data signal as well as the reference signal help to identify aspects of noise that may be affecting the data signal. By iterating as provided in FIG. 3, progressively better and better noise estimates may be obtained, which provides for better demodulation results.

[0051] FIG. 4 illustrates a detailed block diagram of a wireless communication process in a wireless communication system 400, in which a reference signal and a data signal are used to decode the data signal, according to some embodiments of the present disclosure. It will be noted that a channel estimation module 410, a first noise estimation module 420, a noise filter module 430, a demodulation module 440, a decoder module 450, and a second noise estimation module 460 are similar to the corresponding elements of FIG. 3. However, the iterative approach illustrated in FIG. 4 is somewhat different than that of FIG. 3, in that after demodulation by demodulation module 440, results are fed to decoder module 450, and then the decoding result is fed to encoder module 470, where rate-matching, interleaving, and resource mapping may occur. The results of encoder module 470 are then presented for second noise estimation module 460, which iterates again through noise filter module 430, demodulation module 440, and decoder module 450. Here, if the results of the decoder module 450 provide a sufficient quality for the data signal or if a maximum number of iterations have been performed, the decoder module 450 outputs its results. Otherwise, the decoder module 450 feeds back its results to encoder module 470, for a subsequent iteration.

[0052] The modules presented in FIG. 4 may be implemented as software and/or hardware, in a manner similar to that described above with respect to FIG. 3.

[0053] The process presented in FIG. 4 is discussed in greater detail with respect to flowcharts FIGS. 8-11, below, in particular at FIG. 9. By iterating as provided in FIG. 4, as in FIG. 3, progressively better and better noise estimates may be obtained, which provides for better demodulation results. The embodiment of FIG. 4 may potentially provide better results than that of FIG. 3, in that FIG. 4 illustrates an approach in which additional corrective actions are taken during iterations.

[0054] FIGS. 3-4 show an approach in which multiple iterations may be used to progressively improve noise estimation in a wireless communications process 300 or a wireless communication process 400. However, it is to be noted that some embodiments do not use multiple iterations, but instead only perform a single iteration, and the operations performed in such a single iteration are sufficient to act as an embodiment.

[0055] FIG. 5 illustrates a detailed timing of a wireless communication process 500, in which a reference signal and a data signal are used to decode the data signal, according to some embodiments of the present disclosure. In this embodiment, a receiver may process a different number of symbols or RE (resource elements) in different iterations.

[0056] For example, in N1 -symbol or Nl-RE demodulation 510, demodulation module 340 is able to obtain channel information from a first symbol or resource element (RE), in a first iteration. The first iteration also provides an interference and noise covariance update for the next iteration, as discussed in further detail elsewhere in the disclosure. The iterations 520 use the information repeatedly to produce an interference and noise covariance update for the next iteration until a full iteration (i.e., all individual iterations) has been performed. The results of the first iteration and iterations 510, 520 are provided to full-slot demapper 530. Such a full-slot demapper 530 full iteration processes full-slot demodulation 530, meanwhile log-likelihood (LLR) output from demodulation is sent to the decoder 540. Thus, the overall data flow in some embodiments, as illustrated in FIG. 5, is largely similar to that of FIG. 3, but FIG. 5 presents the data flow in a somewhat different way. The operation of the embodiment illustrated in FIG. 3 and FIG. 5 is presented in a flowchart as FIG. 8, below.

[0057] FIG. 6 illustrates a detailed timing of a wireless communication process 600, in which a reference signal and a data signal are used to decode the data signal, according to some embodiments of the present disclosure. FIG. 6 also includes different iterations including the first iteration, following iterations, and a last iteration. N1 -symbols or N1 RE is processed in the first iteration. A full slot is processed in the last iteration providing LLR from demodulation. Elements 610, 620, 630, and 640 are related to elements 510, 520, 530, and 540, respectively, and additional description is omitted for brevity. However, FIG. 6 illustrates a different data flow from that of FIG. 5, especially with respect to later stages of the data flow. In particular, the data flow begins in a similar manner, but FIG. 6 is intended to illustrate the approach of FIG. 4, in which noise covariance can be updated in the middle of each iteration. The operation of the embodiment illustrated in FIG. 3 and FIG. 5 is presented in a flowchart as FIG. 9, below.

[0058] FIGS. 7 A and 7B illustrate block diagrams of a 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.

[0059] It is contemplated that the wireless communication systems described above may be implemented either in software or hardware. For example, FIGS. 7A and 7B illustrate block diagrams of an apparatus 700 including a host chip, an RF chip, and a baseband chip implementing a wireless communication system with iterative signal correction as presented in FIGS. 3-6 in software and hardware, respectively, according to some embodiments of the present disclosure. Apparatus 700 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. 7A and 7B, apparatus 700 may include an RF chip 702, a baseband chip 704A in FIG. 7A or baseband chip 704B in FIG. 7B, a host chip 706, and an antenna 710. In some embodiments, baseband chip 704A or 704B is implemented by processor 1202 and memory 1204, and RF chip 702 is implemented by processor 1202, memory 1204, and transceiver 1206, as described in greater detail below, with respect to FIG. 12. Besides on-chip memory 712 (also known as “internal memory,” e.g., as registers, buffers, or caches) on each chip 702, 704A or 704B, or 706, apparatus 700 may further include a system memory 708 (also known as the main memory) that can be shared by each chip 702, 704A or 704B, or 706 through the main bus. Baseband chip 704A or 704B is illustrated as a standalone system on a chip (SoC) in FIGS. 7A and 7B. However, it is understood that in one example, baseband chip 704A or 704B and RF chip 702 may be integrated as one SoC; in another example, baseband chip 704A or 704B and host chip 706 may be integrated as one SoC; in still another example, baseband chip 704A or 704B, RF chip 702, and host chip 706 may be integrated as one SoC, as described above.

[0060] In the uplink, host chip 706 may generate original data and send it to baseband chip 704A or 704B for encoding, modulation, mapping, and iterative correction. Baseband chip 704A or 704B may access the original data from host chip 706 directly using an interface 714 or through system memory 708 and then prepare the data for processing upon receipt to perform the functions of modules 310, 320, 330, 340, 350, and 360, as described above in detail with respect to FIG. 3, or the functions of modules 410, 420, 430, 440, 450, 460, and 470, as described above in detail with respect to FIG. 4, as non-limiting examples. Baseband chip 704A or 704B then may pass the modulated signal (e.g., the OFDMA symbol) to RF chip 702 through interface 714. A transmitter (Tx) 716 of RF chip 702 may convert the modulated signals in the digital form from baseband chip 704A or 704B into analog signals, i.e., RF signals, and transmit the RF signals through antenna 710 into the channel.

[0061] In the downlink, antenna 710 may receive the RF signals (e.g., the OFDMA symbol) through the channel and pass the RF signals to a receiver (Rx) 718 of RF chip 702. RF chip 702 may perform any suitable front-end RF functions, such as filtering, down-conversion, or samplerate conversion, and convert the RF signals into low-frequency digital signals (baseband signals) that can be processed by baseband chip 704A or 704B. In the downlink, interface 714 of baseband chip 704A or 704B may receive the baseband signals, for example, the OFDMA symbol. Baseband chip 704A or 704B then may perform the iterative correction functions of modules 310, 320, 330, 340, 350, and 360, as described above in detail with respect to FIG. 3, or the functions of modules 410, 420, 430, 440, 450, 460, and 470, as described above in detail with respect to FIG. 4, as nonlimiting examples. The original data may be extracted by baseband chip 704A or 704B from the baseband signals and passed to host chip 706 through interface 714 or stored into system memory 708.

[0062] In some embodiments, the iterative correction schemes disclosed herein (e.g., by wireless communication system 300 or wireless communication system 400) may be implemented in software by baseband chip 704A in FIG. 7A having a baseband processor 720 executing the stored instructions, as illustrated in FIG. 7A. Baseband processor 720 may be a generic processor, such as a central processing unit or a digital signal processor (DSP), not dedicated to iterative correction. That is, baseband processor 720 is also responsible for any other functions of baseband chip 704A and can be interrupted when performing iterative correction due to other processes with higher priorities. Each element in apparatus 700 may be implemented as a software module executed by baseband processor 720 to perform the respective functions described above in detail. [0063] In some other embodiments, the iterative correction schemes disclosed herein, for example, by wireless communication systems 300 or 400, may be implemented in hardware by baseband chip 704B in FIG. 7B having a dedicated iterative correction circuit 722, as illustrated in FIG. 7B. Iterative correction circuit 722 may include one or more integrated circuits (ICs), such as application-specific integrated circuits (ASICs), dedicated to implementing the iterative correction schemes disclosed herein. Each element in wireless communication systems 300 or 400 may be implemented as a circuit to perform the respective functions described above in detail. One or more microcontrollers (not shown) in baseband chip 704B may be used to program and/or control the operations of iterative correction circuit 722. It is understood that in some examples, the iterative correction schemes disclosed herein may be implemented in a hybrid manner, e.g., in both hardware and software. For example, some elements in wireless communication systems 300 or 400 may be implemented as a software module executed by baseband processor 720, while some elements in wireless communication systems 300 or 400 may be implemented as circuits.

[0064] FIG. 8 illustrates a flowchart of a method 800 for receiving data in an OFDM or OFDMA system, according to an embodiment.

[0065] In operation S802, the method does channel estimation and interference/noise estimation based on a reference signal. More specifically, a channel estimation for transmit antenna port p, receive antenna q, symbol i, and reference signal subcarrier j is given by Equation 1 :

_P,q,i,j J \y_P,q,i,j) (Equation 1), where /(•) denotes channel estimation algorithm, and the received reference signal is denoted as

Equation 2:

(Equation 2). In Equation 2, h_{p q 1 }} is a channel for transmit antenna port p, receive antenna q, symbol i and reference signal subcarrier j. n_{q j j} is noise received at receive antenna q, symbol i and reference signal subcarrier j. j» = l,..., ^r _z and . N_t is a total number of antenna ports. N_r is a total number of receiving antennae.

[0066] The interference and noise estimation for receiving antenna q, symbol i, and reference signal subcarrier j based on reference signal is given by Equation 3:

[0067] The interference and noise covariance for resource block rb in iteration 1 (the first iteration) is given by Equation 4:

is the average over all of the reference signals in resource block rb.

In operation S804, the method demodulates the data signal. The received data signal symbol at symbol i and subcarrier j is given by Equation 5: ^J

(Equation 5). In Equation 5, d n JJ and ‘’^j are N_r x 1 vectors. ^, is N_r x N_t and ⁱ is N_r x l .

[0068] It depends on a multiple-input multiple-output (MIMO) scheme that is being used to decide what algorithm is used in the demodulation. If the MIMO scheme is 1 -layer, the demodulation may use interference rejection combining or maximum ratio combining, etc. If it is a multiple-layer MIMO, a demodulation algorithm can be linear or non-linear. Linear MIMO demodulation algorithms include, but are not limited to, minimum mean-square error (MMSE) and zero forcing (ZF). Non-linear MIMO demodulation algorithms include, but are not limited to, maximum likelihood (ML), minimum mean-square error interference cancellation (MMSE-IC), zero forcing interference cancellation (ZF-IC), and Sphere decoding, and so on. Sphere decoding can include fixed-complexity and variable-complexity algorithms.

In operation S804, the demodulated data signal soft-output decision at symbol i and subcarrier j at s ’ = d y R iteration 1 can be given by Equation 6: ^{, rt}>) (Equation 6). In Equation 6, ^(.) represents a demodulation algorithm in iteration 1 and subcarrier j in symbol i is in resource block rb.

[0069] In operation S806, the method performs the next iteration by getting a hard decision of the demodulated data signal and generating a data constellation. In operation S806, a hard decision is made on s ^{7 1} used to obtain signal constellation

for iterations I = 2,... and so on.

[0070] In operation S808, the method regenerates the data signal based on the channel estimation and the hard decision. In operation S808, the signal is regenerated in iteration I according to operations S802 and S806, according to the following result: H_; s^^z .

[0071] In operation S810, the method subtracts the regenerated data signal from the received data signal to get a new estimated interference and noise. More specifically, interference and noise are estimated on the data signal values according to the following Equation 7:

(Equation 7).

[0072] In operation S812, the method updates the interference and noise covariance based on the estimated interference and noise from S810.

For example, the updated interference and noise covariance for resource block rb is given by the following Equation 8: R'_7J

} (Equation 8). In the Equation 8,

is the average over all of the qualified data signal in resource block rb, denoted as < _d(rb) . The qualification of

may be determined by different metrics, including but not limited to a similarity metric based on In some embodiments, it

is possible to add a filtering over interference and noise covariance at different iterations. Such a filter may be a finite impulse response (FIR) filter or an infinite impulse response (IIR) filter. The HR example may be provided according to the following Equation 9:

= R(_i ¹ + (l- )£{_i, _! <_td(_rt) {uL (nL r } (Equation 9). In Equation 9, p is an IIR filter parameter.

[0073] In an iteration other than last iteration, the number of data signal samples used for the iteration may be variable. The number of digital signal samples used may depend on the desired trade-offs between performance and receiver latency, according to a given use case or implementation example.

[0074] In some embodiments, in some iterations, when channel energy h . is small enough, noise is calculated by the following Equation 10: n_q ^l _{i y} = y_{p q i j} (Equation 10). Equation 10 is based on the consideration that if channel energy is small enough, the above equation is totally or approximately true. Using the above equation may help save the complexity of data symbol re-generation. Based on that equation, the updated interference and noise covariance for resource block rb at iteration I is given by the following Equation 11 :

[0075] In operation S814, the method checks to see if the number of symbols reached a maximum in this iteration. If yes, the method proceeds to operation S816. If not, the method proceeds to operation S818 and goes to the next symbol. Accordingly, the method demodulates the data signal at S804 based on the updated interference and noise covariance provided from S812. In operation S804, the demodulated data signal at symbol i and subcarrier j at iteration I can be given by the following Equation 12:

(Equation 12). In Equation 12, d_;(-) represents a demodulation algorithm used in iteration I .

[0076] At different iterations, different algorithms or the same demodulation algorithm with different parameters may be used. In some embodiments, corresponding to a MIMO example, MMSE is used in iteration 1, MMSE-IC is used in iteration 2, and fixed complexity sphere decoding is used in iteration 3. In other embodiments of a MIMO example, a lower complexity fixed complexity sphere decoding is used in iteration 1, and a higher complexity fixed complexity sphere decoding is used in iteration 2.

[0077] In operation S816, the method determines if a number of iterations reaches a maximum or if the quality of the data signal is sufficient or satisfies a condition. For example, the quality of the data signal may be associated with a numerical metric, and it may be required for the numerical metric to be equal to or greater than a threshold value of the numerical metric to be considered sufficient, in this and other examples. In an example where the number of iterations has reached a maximum or the quality of the data signal is sufficient, the iterating may terminate, and the data signal may be provided for decoding in operation S822. If not, the method performs operation S820 to return to operation S804 for the next iteration.

[0078] In operation S822, the method concludes the method by performing the decoding. It is to be noted that once the decoding is performed, the method may additionally output the results of the decoding, such as to other portions of the OFDMA system for further use or processing.

[0079] In the operations of FIG. 8, s^j¹ is directly fed to decoding after iterations are done, according to some embodiments. Alternatively, in some embodiments,

is picked for each i and j among s,-₇’^z obtained in all of the iterations and fed to the decoder after all iterations are done. Such a selection of a demodulated data signal may be based on an intermediate metric obtained in demodulation, including but not limited to a Euclidean distance, a Manhattan distance, and so on. In some embodiment, ^d’¹ from all iterations is fed to a decoder. The decoder then decodes a loglikelihood ratio (LLR) copy from all iterations and decides which results to output according to a CRC check result, a parity check, or a decoding metric.

[0080] FIG. 9 illustrates a flowchart of a method 900 for receiving data in an OFDM or OFDMA system, according to another embodiment.

[0081] In operation S902, the method does channel estimation and interference/noise estimation based on a reference signal. This operation is similar to S802, and a similar description applies, which is omitted for brevity.

[0082] In operation S904, the method demodulates the data signal and does decoding. For example, the modulation performed in S904 is largely similar to that in S804, and a similar description applies, which is omitted for brevity. However, in S904, the LLR is fed to decoding, and a decoder outputs a hard decision result.

[0083] In operation S906, the method performs the next iteration by feeding back a hard decision bit of a code block with a CRC pass. For example, the decoder makes a hard decision, using such a cyclic redundancy check to improve accuracy.

[0084] In operation S908, the method encodes a good decoding hard decision bit and performs operations with the encoded bit, such as rate matching, modulation, interleaving, layer mapping, precoding, and resource matching, etc. The encoding may be used to follow how the transmitter encodes the information bit. Rate matching repeats or punctures the encoded bit to reach a predetermined coding rate. Interleaving changes signal order with a pattern. For example, an input signal is al,a2,a3, a4, but then the output is a4,a2,al,a3. Modulation maps a binary bit into different modulation constellation. Layer mapping maps a modulation signal to different antennae. Resource mapping maps the signal from different antennas to different time and frequency resources.

[0085] Also, in S908, the method regenerates the data signal based on the channel estimation and the hard decoding.

[0086] In operation S910, the method subtracts the regenerated data signal from the received data signal to get new estimated interference and noise. This operation is similar to S810, and a similar description applies, which is omitted for brevity.

[0087] In operation S912, the method obtains interference and noise covariance. This operation is similar to S812, and a similar description applies. The difference between S912 and S812 is that the interference and noise covariance update granularity in S912 is one or multiple code block, while that in S812 can be one or more resource block or symbol or etc. [0088] In operation S914, the method demodulates the data signal based on updated interference and noise covariance. This operation is similar to S814, and a similar description applies, which is omitted for brevity.

[0089] In operation S916, the method does decoding. In operation S918, s ^z is directly fed to decoding after iterations are done in some embodiment. In some embodiments, s ₇ ^,z° is picked for each i and j among s '¹’¹ got in all iterations and fed to a decoder after an iteration is done. The selection can be based on an intermediate metric obtained in demodulation, including but not limited to Euclidean distance, Manhattan distance, and so on. In some embodiments, S ^l:^d’J;‘ from all iterations is fed to a decoder. The decoder will decode an LLR copy from all iterations and decide which results to output according to a CRC check result, a parity check, or a decoding metric.

[0090] In operation S918, the method determines if a number of iterations has reached a maximum or if the quality is sufficient. Operation S918 differs from the decision made in operation S816 in that while the overall criterion used to branch is similar, operation S918 makes the decision after receiving a decoding result from operation S916. In an example where the number of iterations has reached a maximum or the quality of the data signal is sufficient, the iterating may terminate, and the decoded data signal may be provided for outputting in operation S920. If not, the method returns to operation S906 for the next iteration.

[0091] In operation S920, the method outputs the decoding results. In FIG. 9, the data signal has already been decoded by the time at which the determination is made in S918. Thus, in operation S920, the method simply outputs the decoded results, and no additional decoding is needed, as is required in the method presented in FIG. 8.

[0092] FIG. 10 illustrates a flowchart of a method 1000 for receiving data in an OFDM or OFDMA system, according to another embodiment.

[0093] In operation SI 002, the method does channel estimation and interference/noise estimation based on a reference signal. This operation is similar to S802, and a similar description applies, which is omitted for brevity.

[0094] In operation SI 004, the method demodulates a data signal and does decoding for a portion of the new code blocks in a current iteration. This operation is somewhat similar to S904, and a similar description applies, which is omitted for brevity. However, in operation S1004, only a portion of the code blocks within an overall iteration are decoded, and thus in operation SI 004, a portion of code blocks are operated on at a time.

[0095] In operation SI 006, the method encodes good coding hard decision bit and may also do rate matching, interleaving, and resource mapping. This operation is similar to S908, and a similar description applies, which is omitted for brevity.

[0096] In operation SI 008, the method regenerates a data signal based on the channel estimation and the hard decision. This operation is similar to S808, and a similar description applies, which is omitted for brevity.

[0097] In operation S1010, the method subtracts the regenerated data signal from the received data signal to get new estimated interference and noise. This operation is similar to S810, and a similar description applies, which is omitted for brevity.

[0098] In operation S 1012, the method checks to see if a number of code blocks that have been processed has reached a predefined parameter. Such a parameter may be a set number of code blocks or a set proportion of code blocks. By performing such a check, a method according to FIG.

10 includes overall iterations as well as iterations within an iteration where code blocks are processed within an iteration to allow further improved performance. If the number has reached the parameter, the method continues to the next iteration at operation S1014. If not, the method continues to the next group of code blocks at operation S1016.

[0099] In operation S 1014, the method updates interference and noise covariance for the next iteration. This operation is similar to S812, and a similar description applies, which is omitted for brevity.

[0100] In operation S 1016, the method updates interference and noise covariance for new code blocks. This operation is similar to S812, and a similar description applies, which is omitted for brevity. However, this updating is performed for a subgroup of code blocks within an iteration, rather than leading to another whole iteration.

[0101] In operation S 1018, the method checks to see if a number of iterations has reached a maximum or if the quality is sufficient. Operation S 1018 is generally similar to operation S816, except that operation S 1018 is performed after portions of data blocks have been processed as part of an iteration.

[0102] FIG. 11 illustrates a flowchart of a method 1100 for receiving data in an OFDM or OFDMA system, according to another embodiment. FIG. 11 shows a method that captures many of the aspects of the more specific methods provided in FIGS. 8-10, but at a higher level of abstraction and using slightly different phrasing and terminology.

[0103] In operation SI 102, the method includes receiving a reference signal and an initial data signal. In such an operation, the reference signal is received in a way that it is possible to perform channel estimation and interference/noise estimation, and the initial data is received so as to provide information that can be used to facilitate the iteratively improved decoding. For example, such a reference signal and such an initial data signal may be received through an interface, as illustrated in FIG. 7 A and FIG. 7B. [0104] In operation SI 104, the method includes doing channel estimation and first interference/noise estimation based on the reference signal. This operation is similar to S802, and a similar description applies, which is omitted for brevity.

[0105] In operation SI 106, the method includes demodulating the initial data signal to initialize a demodulated data signal. This operation is similar to S804, and a similar description applies, which is omitted for brevity.

[0106] In operation SI 108, the method includes performing the next iteration by producing a hard decision of the demodulated data signal. This operation is similar to S806, and a similar description applies, which is omitted for brevity.

[0107] In operation SI 110, the method includes regenerating a regenerated data signal based on the channel estimation and the hard decision. This operation is similar to S808, and a similar description applies, which is omitted for brevity.

[0108] In operation SI 112, the method includes calculating interference and noise covariance based on a second interference and noise estimation derived by subtracting a regenerated data signal from an initial data signal. This operation is similar to S810 and S812, and a similar description applies, which is omitted for brevity.

[0109] In operation SI 114, the method includes obtaining a corrected demodulated data signal based on demodulating the initial data signal based on the calculated interference and noise covariance. This operation is similar to S814, and a similar description applies, which is omitted for brevity.

[0110] In operation SI 116, the method checks if a number of iterations has reached a maximum or if the quality of the current data signal is sufficient. This operation is similar to S816, and a similar description applies, which is omitted for brevity.

[OHl] In operation SI 118, the method decodes the demodulated data signal. This operation is similar to S818, and a similar description applies, which is omitted for brevity.

[0112] As shown in FIG. 12, receiving device 1200 may include processor 1202. Although only one processor is shown, it is understood that multiple processors can be included. Processor 1202 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 1202 may be a hardware device having one or more processing cores. Processor 1202 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. [0113] As shown in FIG. 12, receiving device 1200 may also include memory 1204. Although only one memory is shown, it is understood that multiple memories can be included. Memory 1204 can broadly include both memory and storage. For example, memory 1204 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 1202. Broadly, memory 1204 may be embodied by any computer-readable medium, such as a non-transitory computer-readable medium.

[0114] Processor 1202, memory 1204, and transceiver 1206 may be implemented in various forms in receiving device 1200 for performing wireless communication with iterative correction functions. In some embodiments, processor 1202, memory 1204, and transceiver 1206 of receiving device 1200 are implemented (e.g., integrated) on one or more system-on-chips (SoCs). In one example, processor 1202 and memory 1204 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 1202 and memory 1204 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 1202 and transceiver 1206 (and memory 1204 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 1208. It is understood that in some examples, some or all of the host chip, baseband chip, and the RF chip may be integrated as a single SoC. For example, a baseband chip and an RF chip may be integrated into a single SoC that manages all the radio functions for cellular communication.

[0115] Various aspects of the present disclosure related to iterative correction 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.

[0116] According to one aspect of the present disclosure, an apparatus including at least one processor and a memory storing instructions is disclosed. The instructions, when executed by the at least one processor, cause the apparatus to receive a reference signal and an initial data signal, perform channel estimation and first interference and noise estimation based on the reference signal, initially demodulate the initial data signal to initialize a demodulated data signal based on the channel estimation and the first interference and noise estimation, perform the following in an iterative manner, until a number of iterations reaches a maximum number or a quality of the demodulated data signal satisfies a condition: produce a hard decision of the demodulated data signal, regenerate a regenerated data signal based on the channel estimation and the hard decision, calculate interference and noise covariance based on second interference and noise estimation derived by subtracting the regenerated data signal from the initial data signal, and obtain a corrected demodulated data signal by demodulating the initial data signal based on the calculated interference and noise covariance, and decode the demodulated data signal.

[0117] In some embodiments, when the corrected demodulated data signal is obtained in a non-final iteration, in a next iteration, the hard decision of the demodulated data signal is produced based on the corrected demodulated data signal.

[0118] In some embodiments, when the corrected demodulated data signal is obtained in a final iteration, the corrected demodulated data signal is used as the demodulated data signal for decoding.

[0119] In some embodiments, the initial data signal comprises Orthogonal Frequency Division Multiplexing (OFDM) symbols.

[0120] In some embodiments, the demodulation for the obtaining occurs in a one-layer multiple-input multiple-output (MIMO) scheme and is performed using interference rejection combining.

[0121] In some embodiments, the demodulation for the obtaining occurs in a multiplelayer multiple-input multiple-output (MIMO) scheme and is performed using a linear MIMO demodulation algorithm.

[0122] In some embodiments, the linear MIMO demodulation algorithm is minimum mean-square error (MMSE) or zero forcing (ZF).

[0123] In some embodiments, the demodulation for the obtaining occurs in a multiplelayer multiple-input multiple-output (MIMO) scheme and is performed using a non-linear MIMO demodulation algorithm.

[0124] In some embodiments, the non-linear MIMO demodulation algorithm is maximum likelihood (ML), minimum mean-square error interference cancellation (MMSE-IC), zero forcing interference cancellation (ZF-IC), fixed-complexity Sphere decoding, or variable-complexity Sphere decoding.

[0125] In some embodiments, the instructions, when executed by the at least one processor, further cause the apparatus to perform a filtering over interference and noise covariance at different iterations, where the filter may be a Finite Impulse Response (FIR) filter or an Infinite Impulse Response (IIR) filter.

[0126] In some embodiments, different demodulation algorithms or the same demodulation with different parameters are used in different iterations for the obtaining.

[0127] In some embodiments, minimum mean-square error (MMSE) is used for the demodulation for the obtaining in a first iteration, minimum mean-square error interference cancellation (MMSE-IC) is used for the demodulation for the obtaining in a second iteration, and fixed complexity Sphere decoding is used for the demodulation for the obtaining in a third iteration.

[0128] In some embodiments, a lower complexity fixed complexity Sphere decoding is used for the demodulation for the obtaining in a first iteration, and a higher complexity fixed complexity Sphere decoding is used for the demodulation for the obtaining in a second iteration. [0129] In some embodiments, the hard decision is made based on a symbol level.

[0130] In some embodiments, the hard decision is made based on a resource element level.

[0131] In some embodiments, the instructions, when executed by the at least one processor, further cause the apparatus to perform any one or any combination of any two or more of rate matching, interleaving, layer mapping and resource mapping.

[0132] In some embodiments, the producing, the regenerating, the calculating, and the obtaining are performed on one or more code blocks at a time, until a predefined number of code blocks are processed, before performing the next iteration.

[0133] In some embodiments, the instructions, when executed by the at least one processor, further cause the apparatus to output the decoded demodulated data signal.

[0134] In some embodiments, the initial demodulation uses log-likelihood ratio (LLR) and soft-output decision decoding.

[0135] In some embodiments, the decoding decides which results to output according to a Cyclic Redundancy Check (CRC) result, a parity check, a Euclidean distance, or a Manhattan distance.

[0136] According to another aspect of the present disclosure, a method for wireless communication is disclosed. The method includes receiving a reference signal and an initial data signal, performing channel estimation and first interference and noise estimation based on the reference signal, initially demodulating the initial data signal to initialize a demodulated data signal based on the channel estimation and an interference and the first interference and noise estimation, performing the following in an iterative manner, until a number of iterations reaches a maximum number or a quality of the demodulated data signal satisfies a condition: producing a hard decision of the demodulated data signal, regenerating a regenerated data signal based on the channel estimation and the hard decision, calculating interference and noise covariance based on second interference and noise estimation derived by subtracting the regenerated data signal from the initial data signal, and obtaining a corrected demodulated data signal by demodulating the initial data signal based on the calculated interference and noise covariance, and decoding the demodulated data signal.

[0137] According to still another aspect of the present disclosure, a baseband chip includes an interface configured to receive a reference signal and an initial data signal, a channel estimation circuit configured to perform channel estimation and first interference and noise estimation based on the reference signal, a demodulation circuit configured to initially demodulate the initial data signal to initialize a demodulated data signal based on the channel estimation and the first interference and noise estimation, an iterative correction circuit, configured to perform the following in an iterative manner, until a number of iterations reaches a maximum number or a quality of the demodulated data signal satisfies a condition: produce a hard decision of the demodulated data signal, regenerate a regenerated data signal based on the channel estimation and the hard decision, calculate interference and noise covariance based on second interference and noise estimation derived by subtracting the regenerated data signal from the initial data signal, and obtain a corrected demodulated data signal by demodulating the initial data signal based on the calculated interference and noise covariance, and a decoder circuit configured to decode the demodulated data signal.

[0138] A benefit of this technology is, at least, to significantly improve receiver performance in the conditions discussed above, specifically where 1) Interference and noise covariance is different in different resource blocks in 4G and 5G and resource units in WI-FI; 2) Interference and noise covariance on reference signal is different from that on a data signal; or 3) the resource allocated for a given user is narrow, e.g., just 1 resource block in 4G/5G or 1 resource unit in WI-FI.

[0139] Because those conditions are very common in real network use cases, the technology improves the overall user experience significantly by facilitating improved receiver performance by aiding in removing as much noise as possible. [0140] The foregoing description of the specific embodiments will so reveal the general nature of the present disclosure that others can, by applying knowledge within the skill of the art, readily modify and/or adapt for various applications such specific embodiments, without undue experimentation, without departing from the general concept of the present disclosure. Therefore, such adaptations and modifications are intended to be within the meaning and range of equivalents of the disclosed embodiments, based on the teaching and guidance presented herein. It is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation, such that the terminology or phraseology of the present specification is to be interpreted by the skilled artisan in light of the teachings and guidance.

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

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

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

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

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: receive a reference signal and an initial data signal; perform channel estimation and first interference and noise estimation based on the reference signal; initially demodulate the initial data signal to initialize a demodulated data signal based on the channel estimation and the first interference and noise estimation; perform the following in an iterative manner, until a number of iterations reaches a maximum number or a quality of the demodulated data signal satisfies a condition: produce a hard decision of the demodulated data signal, regenerate a regenerated data signal based on the channel estimation and the hard decision, calculate interference and noise covariance based on second interference and noise estimation derived by subtracting the regenerated data signal from the initial data signal, and obtain a corrected demodulated data signal by demodulating the initial data signal based on the calculated interference and noise covariance; and decode the demodulated data signal.

2. The apparatus of claim 1, wherein when the corrected demodulated data signal is obtained in a non-final iteration, in a next iteration, the hard decision of the demodulated data signal is produced based on the corrected demodulated data signal.

3. The apparatus of claim 1, wherein when the corrected demodulated data signal is obtained in a final iteration, the corrected demodulated data signal is used as the demodulated data signal for decoding.

4. The apparatus of claim 1, wherein the calculating the interference and noise covariance is done more than once in an iteration.

5. The apparatus of claim 1, wherein the initial data signal comprises Orthogonal Frequency Division Multiplexing (OFDM) symbols.

26

6. The apparatus of claim 1, wherein the demodulation for the obtaining occurs in a one-layer multiple-input multiple-output (MIMO) scheme and is performed using interference rejection combining.

7. The apparatus of claim 1, wherein the demodulation for the obtaining occurs in a multiple-layer multiple-input multiple-output (MIMO) scheme and is performed using a linear MIMO demodulation algorithm.

8. The apparatus of claim 7, wherein the linear MIMO demodulation algorithm is minimum mean-square error (MMSE) or zero forcing (ZF).

9. The apparatus of claim 1, wherein the demodulation for the obtaining occurs in a multiple-layer multiple-input multiple-output (MIMO) scheme and is performed using a non-linear MIMO demodulation algorithm.

10. The apparatus of claim 9, wherein the non-linear MIMO demodulation algorithm is maximum likelihood (ML), minimum mean-square error interference cancellation (MMSE-IC), zero forcing interference cancellation (ZF-IC), fixed-complexity Sphere decoding, or variablecomplexity Sphere decoding.

11. The apparatus of claim 1, wherein the instructions, when executed by the at least one processor, further cause the apparatus to perform a filtering over interference and noise covariance at different iterations, wherein the filter may be a Finite Impulse Response (FIR) filter or an Infinite Impulse Response (IIR) filter.

12. The apparatus of claim 1, wherein different demodulation algorithms or the same demodulation with different parameters are used in different iterations for the obtaining.

13. The apparatus of claim 12, wherein minimum mean-square error (MMSE) is used for the demodulation for the obtaining in a first iteration, minimum mean-square error interference cancellation (MMSE-IC) is used for the demodulation for the obtaining in a second iteration, and fixed complexity Sphere decoding is used for the demodulation for the obtaining in a third iteration.

14. The apparatus of claim 12, wherein a lower complexity fixed complexity Sphere decoding is used for the demodulation for the obtaining in a first iteration, and a higher complexity fixed complexity Sphere decoding is used for the demodulation for the obtaining in a second iteration.

15. The apparatus of claim 1, wherein the hard decision is made based on a symbol level.

16. The apparatus of claim 1, wherein the hard decision is made based on a resource element level.

17. The apparatus of claim 1, wherein the instructions, when executed by the at least one processor, further cause the apparatus to perform any one or any combination of any two or more of rate matching, interleaving, layer mapping, and resource mapping.

18. The apparatus of claim 1, wherein the producing, the regenerating, the calculating, and the obtaining are performed on one or more code blocks at a time, until a predefined number of code blocks are processed, before performing the next iteration.

19. The apparatus of claim 1, wherein the instructions, when executed by the at least one processor, further cause the apparatus to output the decoded demodulated data signal.

20. The apparatus of claim 1, wherein the initial demodulation uses log-likelihood ratio (LLR) and soft-output decision decoding.

21. The apparatus of claim 1, wherein the decoding decides which results to output according to a Cyclic Redundancy Check (CRC) result, a parity check, a Euclidean distance, or a Manhattan distance.

22. A method for wireless communication, comprising: receiving a reference signal and an initial data signal; performing channel estimation and first interference and noise estimation based on the reference signal; initially demodulating the initial data signal to initialize a demodulated data signal, based on the channel estimation and the first interference and noise estimation; performing the following in an iterative manner, until a number of iterations reaches a maximum number or a quality of the demodulated data signal satisfies a condition: producing a hard decision of the demodulated data signal, regenerating a regenerated data signal based on the channel estimation and the hard decision, calculating interference and noise covariance based on second interference and noise estimation derived by subtracting the regenerated data signal from the initial data signal, and obtaining a corrected demodulated data signal by demodulating the initial data signal based on the calculated interference and noise covariance; and decoding the demodulated data signal.

23. A baseband chip, comprising: an interface configured to receive a reference signal and an initial data signal; a channel estimation circuit configured to perform channel estimation and first interference and noise estimation based on the reference signal; a demodulation circuit configured to initially demodulate the initial data signal to initialize a demodulated data signal based on the channel estimation and the first interference and noise estimation; an iterative correction circuit configured to perform the following in an iterative manner, until a number of iterations reaches a maximum number or a quality of the demodulated data signal satisfies a condition: produce a hard decision of the demodulated data signal, regenerate a regenerated data signal based on the channel estimation and the hard decision, calculate interference and noise covariance based on second interference and noise estimation derived by subtracting the regenerated data signal from the initial data signal, and obtain a corrected demodulated data signal by demodulating the initial data signal based on the calculated interference and noise covariance; and a decoder circuit configured to decode the demodulated data signal.

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