CN115176446B

CN115176446B - Apparatus and method for cyclic prefix based time and/or frequency correction

Info

Publication number: CN115176446B
Application number: CN202080096017.5A
Authority: CN
Inventors: 古建; 王原野; 侯平
Original assignee: Zeku Technology Shanghai Corp Ltd
Current assignee: Weiguang Co ltd
Priority date: 2020-02-07
Filing date: 2020-09-15
Publication date: 2023-12-05
Anticipated expiration: 2040-09-15
Also published as: CN115176446A; WO2021156659A1

Abstract

Embodiments of an apparatus and method for Cyclic Prefix (CP) based time and frequency correction are disclosed. In one example, a symbol comprising a CP and a payload is received. The CP is detected and auto-correlation of the CP and the payload is performed. At least one of the time or frequency of the received symbol is adjusted based on the result of the autocorrelation.

Description

Apparatus and method for cyclic prefix based time and/or frequency correction

Cross Reference to Related Applications

The present application claims the benefit of priority from U.S. provisional patent application No. 62/971,608, entitled "POWER SAVING METHOD FOR CP-OFDM base SIGNAL WITH DISCONTINUOUS RECEPTION," filed on 7, 2, 2020, which is incorporated herein by reference in its entirety.

Technical Field

Embodiments of the present disclosure relate to an apparatus and method for wireless communication.

Background

Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcast. Orthogonal frequency division multiplexing (orthogonal frequency division multiplexing, OFDM) is one of the most widely used and employed digital multicarrier modulation methods and has been widely used for cellular communications, such as 4 th generation (4G) Long Term Evolution (LTE) and 5 th generation (5G) new wireless (NR). For example, one version of OFDM used in 4G LTE is cyclic prefix OFDM (CP-OFDM), which has a waveform format designed to overcome inter-symbol interference (inter-symbol interference, ISI) caused by delays and reflections.

Discontinuous reception (discontinuous reception, DRX) mode is a method for mobile communications to conserve battery power of a mobile device. The periodic repetition of the "sleep mode and wake mode" may greatly reduce power consumption of a User Equipment (UE) for receiving data from the network.

Disclosure of Invention

Embodiments of an apparatus and method for wireless communication using Cyclic Prefix (CP) based time and frequency correction are disclosed herein.

In one example, an apparatus is disclosed that includes at least one processor and a memory storing instructions. The instructions, when executed by the at least one processor, cause the apparatus to receive a symbol comprising a CP and a payload. The instructions, when executed by the at least one processor, further cause the apparatus to detect the CP and perform an autocorrelation of the CP and the payload. The instructions, when executed by the at least one processor, further cause the apparatus to adjust at least one of a time or a frequency of the received symbol based on a result of the autocorrelation.

In another example, a baseband chip is disclosed that includes an interface and time and frequency correction circuitry operatively coupled to the interface. The interface is configured to receive an OFDM symbol including a CP and a payload. The time and frequency correction circuit is configured to detect the CP and to perform an autocorrelation of the CP and the payload. The time and frequency correction circuit is further configured to adjust at least one of a time or frequency of the received symbol based on a result of the autocorrelation.

In yet another example, an apparatus for wireless communication is disclosed that includes a data processing module and a time and frequency correction module. The data processing module is configured to receive an OFDM symbol including a CP and a payload. The time and frequency correction module is configured to detect the CP and to perform an autocorrelation of the CP and the payload. The time and frequency correction module is further configured to adjust at least one of a time or frequency of the received symbol based on a result of the autocorrelation. The data processing module is further configured to process the OFDM symbols based on the adjusted time or frequency.

In yet another example, a method for time and/or frequency correction is disclosed. A symbol including a CP and a payload is received. Detecting the CP and performing an autocorrelation of the CP and the payload. At least one of the time or frequency of the received symbol is adjusted based on the result of the autocorrelation.

In yet another example, a non-transitory computer-readable medium encoded with instructions that, when executed by at least one processor of a terminal device, perform a process is disclosed. The process comprises the following steps: a symbol including a CP and a payload is received. The process further includes: detecting the CP and performing an autocorrelation of the CP and the payload. The process further includes: at least one of the time or frequency of the received symbol is adjusted based on the result of the autocorrelation.

In yet another example, an apparatus for time and/or frequency correction is disclosed that includes a receiving module, a detecting module, an autocorrelation module, and a time or frequency correction module. The receiving module is configured to receive an OFDM symbol including a Cyclic Prefix (CP) and a payload. The detection module is configured to detect the CP. The autocorrelation module is configured to perform an autocorrelation of the CP and the payload. The time or frequency correction module is configured to adjust at least one of a time or frequency of the received symbol based on a result of the autocorrelation.

Drawings

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 disclosure and to enable a person skilled in the pertinent art to make and use the disclosure.

Fig. 1 illustrates an exemplary wireless network according to some embodiments of the present disclosure.

Fig. 2 illustrates a detailed block diagram of an exemplary wireless communication system using CP-based time and frequency correction in accordance with some embodiments of the present disclosure.

Part a of fig. 3 shows a schematic diagram of an exemplary CP addition procedure applied to an OFDM symbol stream in the wireless communication system of fig. 2 according to some embodiments of the present disclosure.

Part B of fig. 3 illustrates autocorrelation results of CPs and payloads in the time domain in the wireless communication system of fig. 2 according to some embodiments of the present disclosure.

Fig. 4 illustrates a timing diagram of exemplary time and frequency corrections performed when a receiving device wakes up in the wireless communication system of fig. 2, according to some embodiments of the present disclosure.

Fig. 5A and 5B illustrate block diagrams of exemplary devices including a host chip, a Radio Frequency (RF) chip, and a baseband chip, respectively, implementing the wireless communication system of fig. 2 in software and hardware, respectively, according to some embodiments of the present disclosure.

Fig. 6 illustrates a flowchart of an exemplary method for CP-based time and frequency correction in accordance with some embodiments of the present disclosure.

Fig. 7 illustrates a flowchart of an exemplary method for autocorrelation of the CP-based time and frequency correction method of fig. 6 in accordance with some embodiments of the present disclosure.

Fig. 8 illustrates a flowchart of another exemplary method for CP-based time and frequency correction in accordance with some embodiments of the present disclosure.

Fig. 9 illustrates a block diagram of an exemplary receiving device, according to some embodiments of the present disclosure.

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

Detailed Description

While specific configurations and arrangements are discussed, it should be understood that this is for illustrative purposes only. One skilled in the relevant art will recognize that other configurations and arrangements may be used without departing from the spirit and scope of the disclosure. It will be apparent to those skilled in the relevant art that the present disclosure may also be used in a variety of other applications.

It should be noted that references in the specification to "one embodiment," "an example embodiment," "some 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 are not necessarily referring to the same embodiment. Furthermore, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the relevant art to effect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

Generally, the term may be understood, at least in part, from the use of context. For example, the term "one or more" as used herein may be used to describe any feature, structure, or characteristic in the singular or may be used to describe a combination of features, structures, or characteristics in the plural, depending at least in part on the context. Similarly, again depending at least in part on the context, terms such as "a," "an," or "the" are to be understood to convey a singular use or to convey a plurality of uses. In addition, it is to be understood that the term "based on" is not necessarily intended to convey an exclusive set of factors, but instead may allow for additional factors to be present that again are not necessarily explicitly described, depending at least in part on the context.

Various aspects of a wireless communication system will now be described with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and are 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.

The techniques described herein may be used for various wireless communication networks such as Code Division Multiple Access (CDMA) systems, time Division Multiple Access (TDMA) systems, frequency Division Multiple Access (FDMA) systems, orthogonal Frequency Division Multiple Access (OFDMA) systems, single carrier frequency division multiple access (SC-FDMA) systems, and other networks including, but not limited to, 4G LTE and 5G NR cellular networks. The terms "network" and "system" are often used interchangeably. The techniques described herein may be used for the wireless networks mentioned above and other wireless networks.

Discontinuous Reception (DRX) is a method for mobile communication to save battery of a mobile device. The periodic repetition of the "sleep mode and wake mode" may greatly reduce power consumption of a User Equipment (UE) for receiving data from the network. To reduce the power consumed by the UE, the UE stops listening on the channel, stays in sleep mode (i.e., idle mode) for a period of time, and wakes up for an interval of time. During sleep (e.g., periods in sleep mode), a master clock (e.g., a high resolution clock source and a processor portion associated with the clock) for ensuring synchronization of the UE is turned off. Thus, due to sleep, time and/or frequency drift may occur.

In order to perform time and frequency correction (i.e., synchronization) after waking up from a sleep mode, in conventional Discontinuous Reception (DRX) techniques, additional wake-up time is required to receive one or more reference signals, based on which time and frequency correction is performed.

For example, in the 4G and LTE scenarios, when the UE wakes up from sleep mode, the UE starts the RF module before an active period (onDuration) or Paging Occasion (PO) of a modulation symbol corresponding to the original data is received (e.g., before a PO in which the UE is in a radio resource control (radio resource control, RRC) idle mode, or before an active period in which the UE is in an RRC connected mode). In some embodiments, time and frequency correction is performed based on one or more cell-specific reference signals (cell specific reference signal, CRS), and the additional wakeup duration is one or more LTE/4G subframes for receiving CRS. Using CRS-based algorithms, the UE may perform channel estimation based on the CRS and may perform time and frequency correction based on the channel estimation.

In some other embodiments, if the time and/or frequency drift is higher than the CRS can track, a cell search based on the primary synchronization signal (primary synchronization signal, PSS), secondary synchronization signal (secondary synchronization signal, SSS) may be performed. Thus, additional wake-up (e.g., prior to the PO or active period time slot) may be required to receive the PSS/SSS.

For another example, in a 5G scenario, time and frequency correction may be performed based on a synchronization signal block (synchronization signal block, SSB). The SSB is 4 symbols in duration and may not be aligned with the PO or activation period. Thus, the UE may need to perform additional wake-up to receive the SSB to correct time and frequency errors based on the SSB. All of the above additional wake-up times result in additional UE power being consumed to perform time and frequency corrections.

In accordance with various embodiments of the present disclosure, systems and methods are provided for time and frequency correction based on the CP of a received symbol. The CP of a symbol may be an exact copy of the last portion of the symbol (e.g., a predetermined length such as 16 samples, 128 samples, etc.), which is copied to the front of the signal. CP is designed to overcome inter-symbol interference (ISI) caused by delays and reflections (e.g., multipath interference). Time and frequency correction may be performed based on detecting the CP of the symbol and performing an autocorrelation of the CP of the symbol and the payload. Thus, no additional wake-up is required for time and frequency correction and the power consumption of the UE can be reduced as desired.

The time or frequency of the symbol is adjusted based on one or more peaks of the autocorrelation. Because the CP is a copy of the last part of the symbol (e.g., the last part of the payload), ideally the highest peak of the autocorrelation in the time domain between the CP and the payload can provide information related to time error (e.g., indicating the end position of the symbol with drift), and the phase of the peak in the frequency domain can provide information related to frequency error. Based on detecting the end position of the symbol, time and frequency corrections may be performed on the symbol. In some embodiments, the time and frequency drift of the symbols may be corrected according to the communication protocol used to transmit the symbols. For example, the time and frequency drift of the symbol may be corrected according to a predetermined sampling frequency (e.g., predetermined based on a communication protocol) for demodulating the symbol based on the time and frequency of the symbol indicated by the result of the autocorrelation.

In some embodiments, more than one peak above a threshold may be detected in correlation due to interference (e.g., inter-symbol interference (ISI) and multipath interference) (e.g., the threshold is set to ensure that the peaks are not caused by some random similarity within the payload of the symbol). For example, due to multipath problems, one or more delayed copies of a symbol may be received and peaks may be displayed where the delayed copies end. In some embodiments, because the delayed copies are received after a delay due to a long transmission path, the earliest peak above the threshold may be selected to locate the end of the symbol. In some other embodiments, the peak indicating the end of the delayed replica may be weaker (e.g., have a smaller amplitude in the autocorrelation result) than the peak indicating the end of the received symbol because the delayed replica is reflected by surrounding objects. Thus, the strongest peak (e.g., the highest peak in the autocorrelation result) may be selected to locate the end of the symbol.

In some embodiments, the length of the CP (e.g., bit or time span) may be insufficient to mask the effects caused by ISI. For example, the time span of more than one peak above the threshold is longer than the time span of the CP (e.g., the time span between the first and last peak of more than one peak is longer than the time span of the CP). In some embodiments, the received symbols may be converted into multiple copies according to a number of peaks above a threshold, the peaks being separated from each other by at least a time span of the CP. Time and frequency corrections may be performed separately for each copy of the symbol (e.g., performing correlation of CP and payload for each copy), and each copy may be processed based on the adjusted time or frequency of the copy, respectively (e.g., converting from time domain to frequency domain, demodulating each copy, etc.). The output of the demodulation process may be selected from the processed copies based on a metric of each processed copy, e.g., the quality of the copy, e.g., signal-to-noise ratio (SNR).

In some embodiments, when a valid CP is not detected, or a peak above a threshold is not detected (e.g., because the quality of the received symbol is poor), the symbol may be processed without performing time and frequency correction (e.g., using default timing), or using an alternative method for performing time and frequency correction (e.g., using one of the reference signal-based time and frequency correction methods in conventional DRX techniques).

In some embodiments, the condition of the received symbol may also be used to determine an activity for a subsequent wakeup (e.g., a time and frequency correction method to be performed) and/or a starting point in time of the subsequent wakeup (e.g., to receive one or more reference signals if additional wakeup is required).

Fig. 1 illustrates an example 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, a wireless network 100 may include a network of nodes, such as a UE 102, an access node 104, and a core network element 106. The user device 102 may be any terminal device, such as a mobile phone, a desktop computer, a laptop computer, a tablet computer, a vehicle computer, a game 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 (IoT) node. It should be understood that the user device 102 is shown as a mobile phone by way of illustration only and not by way of limitation.

The access node 104 may be a device in communication with the 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 node B (gndeb or gNB), a cluster master node, or the like. The access node 104 may have a wired connection to the UE 102, a wireless connection to the UE 102, or any combination thereof. The access node 104 may be connected to the UE 102 through a plurality of connections, and the UE 102 may also be connected to other access nodes in addition to the access node 104. The access node 104 may also be connected to other UEs. It should be understood that access node 104 is illustrated by a radio tower by way of illustration and not limitation.

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

The core network element 106 may be connected to a large network, such as the internet 108 or another Internet Protocol (IP) network, to communicate packet data over any distance. In this manner, data from the user device 102 may be transferred to other user devices connected to other access points, including, for example, a computer 110 connected to the Internet 108 using a wired or wireless connection, or a tablet 112 connected wirelessly to the Internet 108 through a router 114. Thus, computer 110 and tablet 112 provide additional examples of possible user devices, and router 114 provides examples of another possible access node.

A typical example of a rack-mounted server is provided by the illustrated core network element 106. However, there may be multiple elements in the core network, including database servers such as database 116, and security and authentication servers such as authentication server 118. For example, database 116 may manage data related to user subscriptions for web services. The home location register (home location register, HLR) is an example of a standardized database of subscriber information for cellular networks. Similarly, authentication server 118 may handle authentication, sessions, etc. of users. In an NR system, an authentication server function (authentication server function, AUSF) device may be a specific entity performing user equipment authentication. In some embodiments, a single server chassis may handle multiple such functions, such that the connections between the core network element 106, authentication server 118, and database 116 may be local connections within the single chassis.

As described in detail below, in some embodiments, wireless communications may be established between any suitable node in the wireless network 100, e.g., between the UE 102 and the access node 104, and between the UE 102 and the core network element 106, for transmitting and receiving data (e.g., one or more OFDM symbols). The transmitting node may generate one or more OFDM symbols (e.g., perform mapping, serial-to-parallel, inverse fast fourier transform (inverse fast Fourier transform, IFFT), CP addition, parallel-to-serial, etc.) and transmit the symbols to a receiving device (e.g., UE). When the receiving device wakes up from the sleep mode and receives the symbol, the receiver may detect the CP, perform an autocorrelation of the CP and the payload of the symbol, and adjust at least one of a time or frequency of the symbol based on a result of the automatic correction.

Each node of the wireless network 100 in fig. 1 adapted for DRX may be considered a receiving device. Further details regarding possible implementations of the receiving device are provided by way of example in the description of the receiving device 900 in fig. 9. The receiving device 900 may be configured as the user equipment 102, the access node 104 or the core network element 106 in fig. 1. Similarly, the receiving device 900 may also be configured as the computer 110, router 114, tablet 112, database 116, or authentication server 118 of fig. 1. As shown in fig. 9, the receiving device 900 may include a processor 902, a memory 904, and a transceiver 906. These components are shown connected to each other by a bus, but other connection types are also allowed. When the receiving device 900 is the user device 102, additional components may also be included, such as User Interfaces (UIs), sensors, and the like. Similarly, when the receiving device 900 is configured as a core network element 106, the receiving device 900 may be implemented as a blade in a server system. Other implementations are also possible.

Transceiver 906 may include any suitable device for transmitting and/or receiving data. The receiving device 900 may include one or more transceivers, although only one transceiver 906 is shown for simplicity of illustration. Antenna 908 is shown as a possible communication mechanism for receiving device 900. If the antennas are MIMO, multiple antennas and/or antenna arrays may be utilized. In addition, examples of the receiving device 900 may communicate using wired technology rather than wireless technology (or in addition to wireless technology). For example, the access node 104 may communicate wirelessly with the user device 102 and may communicate with the core network element 106 through a wired connection (e.g., through an optical or coaxial cable). Other communication hardware may also be included, such as a network interface card (network interface card, NIC).

As shown in fig. 9, the receiving device 900 may include a processor 902. Although only one processor is shown, it should be understood that multiple processors may be included. The processor 902 may include a microprocessor, microcontroller, digital signal processor (digital signal processor, DSP), application-specific integrated circuit (ASIC), field-programmable gate array (FPGA), programmable logic device (programmable logic device, PLD), state machine, gating logic, discrete hardware circuits, and other suitable hardware configured to perform the various functions described throughout this disclosure. The processor 902 may be a hardware device having one or more processing cores. The processor 902 may run software. Software should be construed broadly to mean instructions, instruction sets, code segments, program code, programs, subroutines, software modules, applications, software packages, routines, subroutines, objects, executable files, threads of execution, procedures, functions, etc., whether the software is referred to as software, firmware, middleware, microcode, hardware description language, or otherwise stated. The software may include computer instructions written in an interpreted language, compiled language, or machine code. Other techniques for indicating hardware are also allowed to fall under the broad category of software.

As shown in fig. 9, the receiving device 900 may also include a memory 904. Although only one memory is shown, it should be understood that multiple memories may be included. Memory 904 may broadly include both memory and storage devices. For example, the memory 904 may include Random Access Memory (RAM), read Only Memory (ROM), static RAM (SRAM), dynamic RAM (DRAM), ferroelectric RAM (FRAM), electrically Erasable Programmable ROM (EEPROM), CD-ROM or other optical disk storage, a Hard Disk Drive (HDD), such as magnetic disk storage or other magnetic storage devices, a flash memory drive, a Solid State Drive (SSD), or any other medium that may be used to carry or store desired program code in the form of instructions that may be accessed and executed by the processor 902. In a broad sense, the memory 904 can be implemented by any computer-readable medium (e.g., non-transitory computer-readable medium).

The processor 902, memory 904, and transceiver 906 may be implemented in various forms in the receiving device 900 for performing wireless communication using CP-based time and frequency correction functions. In some embodiments, the processor 902, memory 904, and transceiver 906 of the receiving device 900 are implemented (e.g., integrated) on one or more systems-on-chip (SoC). In one example, processor 902 and memory 904 may be integrated on an Application Processor (AP) SoC (sometimes referred to herein as a "host," referred to as a "host chip") that processes application processing in an operating system environment, including generating raw data to be transmitted. In another example, the processor 902 and memory 904 may be integrated on a baseband processor (baseband processor, BP) SoC (sometimes referred to herein as a modem, referred to as a "baseband chip") that converts raw data, e.g., from a host chip, into signals that can be used to modulate a carrier frequency for transmission, and vice versa, the BP SoC may run a real-time operating system (real-time operating system, RTOS). In yet another example, the processor 902 and transceiver 906 (and in some cases, memory 904) may be integrated on an RF SoC (sometimes referred to herein as a transceiver, referred to as an "RF chip") that transmits and receives RF signals using antenna 908. It should be appreciated that in some examples, some or all of the host chip, baseband chip, and RF chip may be integrated into a single SoC. For example, the baseband chip and the RF chip may be integrated in a single SoC that manages all radio functions for cellular communications.

Aspects of the present disclosure related to time and frequency correction may be implemented as software and/or firmware elements executed by a general-purpose processor (e.g., baseband processor) in a baseband chip. It should be appreciated 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, such dedicated hardware components including Integrated Circuits (ICs), such as Application Specific Integrated Circuits (ASICs). Implementations of the present disclosure may be located at layer 1 (e.g., physical (PHY) layer) by mapping to a wireless communication (e.g., 4g, lte,5g, etc.) layer architecture.

Fig. 2 illustrates a detailed block diagram of an exemplary wireless communication system 200 using CP-based time and frequency correction in accordance with some embodiments of the present disclosure. The wireless communication system 200 may be used between suitable nodes in the wireless network 100. As shown in fig. 2, a wireless communication system 200 may include a transmitting device 201 and a receiving device 202. For example, the transmitting device 201 may be an example of the user device 102, the access node 104, or the core network element 106, and the receiving device 202 may be an example of the user device 102 or the core network element 106 of the wireless network 100 in fig. 1. The wireless communication system 200 may be used to save power consumption of the receiving device 202 and improve accuracy of wireless communications by providing better synchronization performance. The transmitting device 201 and the receiving device 202 may each include a processor, a memory, and a transceiver, which may be examples of the processor 902, the memory 904, and the transceiver 906 described in detail above with respect to fig. 9, respectively.

As shown in fig. 2, a transmitting device 201 may process raw data (e.g., input data through various functional stages of data modulation, mapping, IFFT, CP addition, etc.), and may transmit the processed data (e.g., OFDM symbols) to a receiving device 202. The receiving device 202 may receive the symbols, perform time and frequency correction, and detect the original data (e.g., decoded bits) through an inverse process (e.g., demodulation, demapping, CP removal, FFT, etc.).

As shown in fig. 2, the transmitting apparatus 201 may include a data mapping module 210, an OFDM modulation module 220, and a CP adding module 230 for processing original data to be transmitted.

For example, the data mapping module 210 may apply a mapper (e.g., quadrature phase shift keying (quadrature phase shift keying, QPSK)) to group information bits of the original data into symbols. In the OFDM modulation module 220, IFFT (for example, when the number of subcarriers is 2 ⁿ Time) or an inverse discrete fourier transform (inverse discrete Fourier transform, IDFT) may be applied to the symbols to keep the subcarriers still orthogonal. CP adding module 230 may add a CP to a symbol by taking the last portion of a predetermined length (e.g., number of bits) and copying the last portion to the front of the symbol. For example, section a of fig. 3 shows a schematic diagram of an exemplary CP addition process applied to symbol stream 302 of OFDM symbol 304 in accordance with some embodiments of the present disclosure.

As shown in part a of fig. 3, each OFDM symbol 304 may include a payload 306 carrying data and a CP 308 located at the beginning of the OFDM symbol 304. In some embodiments, the last portion of payload 306 is inserted at the beginning of payload 306 of OFDM symbol 304 as CP 308. In some embodiments, CP 308 may be used as a guard interval to prevent ISI between consecutive OFDM symbols 304.

Referring back to fig. 2, ofdm symbols may be transmitted to the receiving device 202 over a channel (e.g., one or more communication links between the transmitting device 201 and the receiving device 202). When receiving device 202 wakes up from sleep mode, CP-based time and frequency correction module 240 may perform time and frequency correction based on performing an autocorrelation of the CP (e.g., CP 308) and the payload (e.g., payload 306) of an OFDM symbol (e.g., OFDM symbol 304) upon receipt of the OFDM symbol.

For example, fig. 4 illustrates a timing diagram of exemplary time and frequency corrections performed when the receiving device 202 wakes up according to some embodiments of the present disclosure. As shown in fig. 4 a) to 4 c), in the conventional DRX technique performing the conventional time and frequency correction scheme, an additional wake-up period (e.g., wake-up in addition to the PO or active period) is required in the DRX cycle (e.g., a time span from the start of the PO or active period to the start of the next PO or active period) for receiving one or more reference signals (e.g., CRS, PSS/SSS, SSB, etc.) for performing the time and frequency correction. Thus, the UE (e.g., receiving device 202) requires additional power consumption to adjust the time or frequency accordingly.

As shown in fig. 4 d), no additional wake-up period is required to perform CP-based time and frequency correction for the same DRX cycle, since the CP is aligned with the payload of the OFDM symbol. Thus, this may greatly reduce the power consumption of the receiving device 202. Furthermore, using CPs (e.g., having significantly fewer bits than the entire OFDM symbol) to perform the correction with the payload of the OFDM symbol (as will be described in detail in connection with the description of section B of fig. 3 below) may further save a significant amount of computational resources for performing the time and frequency correction as compared to other autocorrelation-based time and frequency detection where the entire OFDM symbol is used for correlation.

Referring back to fig. 2, the CP-based time and frequency correction module 240 may include a CP detection unit 242, an autocorrelation unit 244, and a time and frequency correction unit 246. In some embodiments, CP detection unit 242 may detect a CP (e.g.,CP 308 in part a of fig. 3). When starting to receive the payload of an OFDM symbol (e.g., OFDM symbol 304), autocorrelation unit 224 may begin to perform an autocorrelation of the CP (e.g., CP 308) and the payload (e.g., payload 306). For example, part B of fig. 3 shows the autocorrelation results of CP 308 and payload 306 in the time domain, according to some embodiments of the present disclosure. In part B of fig. 3, the "T" axis represents time, and the "Amplitude" axis represents the magnitude of the autocorrelation result. T (T) ₀ An end time point of the OFDM symbol 304 is represented. As shown in part B of fig. 3, when the correlation window moves from the beginning of payload 306 to the end of payload 306, a peak above a threshold (e.g., a threshold set to avoid peaks caused by some random similarities within portions of the OFDM symbol) may indicate the location of the end of OFDM symbol 304 because CP 308 is an exact copy of the last portion of payload 306. In some embodiments, multiple peaks in the autocorrelation result may be above a threshold. For example, delayed copies of symbols may be received due to interference (e.g., ISI and multipath interference). Since the delayed copy of the symbol has weaker energy (e.g., the delayed copy of the symbol is reflected, thus losing part of the energy), the peak with the highest amplitude (e.g., corresponding to the strongest received symbol) may be used to indicate the location of the end of the OFDM symbol 304.

Referring back to fig. 2, based on the location of the end of the OFDM symbol, the time and frequency correction unit 246 may adjust the time or frequency of the OFDM symbol to correct time and/or frequency drift caused by being in sleep mode accordingly.

In some embodiments, OFDM symbols with adjusted time or frequency may be sent to the data processing module 250 for extraction of the original data. For example, the data processing module 250 may convert the conditioned OFDM symbols from the time domain to the frequency domain using a Fast Fourier Transform (FFT), and may demodulate and demap the symbols based on the conditioned time or frequency using channels such as a Physical Downlink Control Channel (PDCCH) receiver and/or a Physical Downlink Shared Channel (PDSCH) receiver. The raw data (e.g., data input of the transmitting device 201) may be the output of the data processing module 250.

In some embodiments, more than one peak above the threshold may be detected in the autocorrelation result due to interference (e.g., ISI and multipath interference). For example, due to multipath problems, one or more delayed copies of a symbol may be received and one or more peaks may be displayed at the end of the delayed copies.

In some embodiments, if the time span between peaks is not longer than the time span of the CP, the time and frequency correction unit 246 may adjust the time or frequency of the received OFDM symbol based on the earliest or strongest peak above a threshold. For example, because the delayed copies are received after a certain delay due to a longer transmission distance, the earliest peak above the threshold may be selected to locate the end of the symbol. For another example, because the delayed replica is reflected by surrounding objects, the peak corresponding to the delayed replica may be weaker (e.g., have a smaller amplitude in the autocorrelation result) than the peak indicating the end of the received symbol. Thus, the strongest peak (e.g., the highest peak in the autocorrelation result) may be selected to locate the end of the symbol.

In some embodiments, the time span of more than one peak above the threshold is longer than the time span of the CP. In some embodiments, the received symbols may be converted into multiple copies according to a number of peaks above a threshold, the peaks being separated from each other by at least a time span of the CP. Time and frequency correction may be performed on each replica (e.g., correlating CP and each replica), respectively, and each replica may be processed (e.g., converting from time domain to frequency domain, demodulating each replica, etc.) based on the adjusted time or frequency of the replica, respectively. The output of the demodulation process may be selected from the processed copies based on a metric of each processed copy, e.g., a quality of the copy, e.g., signal-to-noise ratio (SNR).

In some embodiments, if a valid CP is not detected, the OFDM symbol may be processed without performing time and frequency correction (e.g., using default timing), or using an adjusted time or frequency determined by an alternative time and frequency correction method (e.g., using one of the reference signal-based time and frequency correction methods in conventional DRX techniques). Therefore, in this scenario, the CP-based time and frequency correction performed in the CP-based time and frequency correction module 240 (e.g., the processing performed in the autocorrelation unit 244, and the time and frequency correction unit 246) will not be performed. For one example, the OFDM symbols may be sent to the data processing module 250 for further processing, but not necessarily to update time and frequency drift. In other embodiments, the receiving device 202 may initiate FFT functions and associated PDCCH receivers in the data processing module 250, attempt to decode the PDCCH, and obtain PDCCH demodulation reference signals (DMRS) or CRS to perform time and frequency correction.

In some embodiments, based on the received symbols, the time and frequency correction for the current wakeup may be used as a quality criterion for determining the activity of the subsequent wakeup (e.g., the time and frequency correction module to be used) and/or the starting point in time of the subsequent wakeup. For example, the receiving device 202 may further include an optional time and frequency correction module 260, with optional time and frequency correction methods (e.g., methods based on one or more reference signals) being performed in the optional time and frequency correction module 260. The time and frequency correction module selection process may be controlled by a processor (e.g., processor 902) in conjunction with control signals provided by time and frequency correction module selection module 270 in accordance with one or more of the schemes disclosed above. For one example, if a CP correlation peak above a threshold is not detected in the current wake-up (e.g., due to a lower quality of the received symbols), then in subsequent wake-ups, an alternative time and frequency correction module 260 may be selected to make the time and frequency correction, and may also indicate an early wake-up (e.g., with additional wake-ups for receiving one or more reference signals).

It is contemplated that possible time and frequency correction modules and time and frequency correction module selection methods for time and frequency correction are not limited to those disclosed herein. Any other suitable alternative time and frequency correction module and time and frequency correction module selection method may be applied to the time and frequency correction by the receiving device 202. However, based on the selected time and frequency correction module, the adjusted OFDM symbols may be sent to the data processing module 250 for further processing based on the adjusted time or frequency.

It is contemplated that the wireless communication system 200 with CP-based time and frequency correction described above may be implemented in software or hardware. For example, fig. 5A and 5B illustrate block diagrams of exemplary apparatus 500 including a host chip, an RF chip, and a baseband chip, respectively, implementing the wireless communication system 200 in fig. 2 in software and hardware, respectively, according to some embodiments of the present disclosure, the wireless communication system 200 having CP-based time and frequency correction. The apparatus 500 may be an example of any node (e.g., user equipment 102 or core network element 106) of the wireless network 100 of fig. 1 adapted for DRX. As shown in fig. 5, device 500 may include an RF chip 502, a baseband chip 504 (baseband chip 504A in fig. 5A or baseband chip 504B in fig. 5B), a host chip 506, and an antenna 510. In some embodiments, baseband chip 504 is implemented by processor 902 and memory 904, and RF chip 502 is implemented by processor 902, memory 904, and transceiver 906, as described above with respect to fig. 9. In addition to on-chip memory 512 (also referred to as "internal memory," e.g., as registers, buffers, or caches) on each chip 502, 504, or 506, the apparatus 500 may further include a system memory 508 (also referred to as main memory), which system memory 508 may be shared by each chip 502, 504, or 506 over a main bus. Although the baseband chip 504 is shown as a stand-alone SoC in fig. 5A and 5B, it should be understood that in one example, the baseband chip 504 and the RF chip 502 may be integrated as one SoC; in another example, baseband chip 504 and host chip 506 may be integrated as one SoC; in yet another example, the baseband chip 504, the RF chip 502, and the host chip 506 may be integrated as one SoC, as described above.

In the uplink, the host chip 506 may generate raw data and send the raw data to the baseband chip 504 for encoding, modulation, mapping, and CP addition. Baseband chip 504 may access raw data from host chip 506 directly using interface 514 or through system memory 508 and then perform the functions of modules 210, 220, and 230 as described in detail above with respect to fig. 2. Baseband chip 504 may then transmit the modulated signal (e.g., OFDM symbol) to RF chip 502 via interface 514. A transmitter (Tx) 516 of the RF chip 502 may convert the modulated signal in digital form from the baseband chip 504 into an analog signal, i.e., an RF signal, and transmit the RF signal into a channel through the antenna 510.

In the downlink, an antenna 510 may receive RF signals (e.g., OFDM symbols) over a channel and communicate the RF signals to a receiver (Rx) 518 of the RF chip 502.RF chip 502 may perform any suitable front-end RF functions (e.g., filtering, down-conversion, or sample rate conversion) and convert the RF signals to low frequency digital signals (baseband signals) that may be processed by baseband chip 504. In the downlink, an interface 514 of the baseband chip 504 may receive baseband signals, e.g., OFDM symbols. Baseband chip 504 may then perform the functions of modules 240, 250, 260, and 270, as described in detail above with respect to fig. 2, part a of fig. 3, and part B of fig. 3. Raw data may be extracted from baseband signals by baseband chip 504 and transferred to host chip 506 through interface 514 or stored in system memory 508.

In some embodiments, the time and frequency correction schemes disclosed herein (e.g., by CP-based time and frequency correction module 240, instead of time and frequency correction module 260, or wireless communication system 200) may be implemented in software by baseband chip 504A in fig. 5A, baseband chip 504A having a baseband processor 520 executing stored instructions, as shown in fig. 5A. Baseband processor 520 may be a general purpose processor, such as a central processing unit or DSP, that is not dedicated to time and frequency correction. That is, the baseband processor 520 is also responsible for any other functions of the baseband chip 504A, and when performing time and frequency correction, the baseband processor 520 may be interrupted due to other processes having higher priority. Each element in the apparatus 500 may be implemented as a software module that is executed by the baseband processor 520 to perform the corresponding functions described in detail above.

In some other embodiments, the time and frequency correction schemes disclosed herein (e.g., by CP-based time and frequency correction module 240, instead of time and frequency correction module 260 or wireless communication system 200) may be implemented in hardware by baseband chip 504B in fig. 5B, baseband chip 504B having dedicated time and frequency correction circuitry 522, as shown in fig. 5B. The time and frequency correction circuit 522 may include one or more ICs, such as ASICs, dedicated to implementing the time and frequency correction detection schemes disclosed herein. Each element in the wireless communication system 200 may be implemented as circuitry that performs the corresponding functions described in detail above. One or more microcontrollers (not shown) in baseband chip 504B may be used to program and/or control the operation of time and frequency correction circuit 522. It should be appreciated that in some examples, the time and frequency correction detection schemes disclosed herein may be implemented in a hybrid manner, e.g., in both hardware and software. For example, some elements of the wireless communication system 200 may be implemented as software modules executed by the baseband processor 520, while some elements of the wireless communication system 200 may be implemented as circuitry.

Fig. 6 and 7 illustrate a flow chart of an exemplary method 600 for wireless communication using CP-based time and frequency correction, and fig. 8 illustrates a flow chart of another exemplary method 800 for wireless communication using CP-based time and frequency correction, according to some embodiments of the present disclosure. Examples of devices that may perform the operations of methods 600 and 800 include, for example, the devices depicted in fig. 2, 5A, and 5B, or any other device disclosed herein. It should be understood that the operations illustrated in methods 600 and 800 are not exhaustive, and that other operations may be performed before, after, or between any of the illustrated operations. Further, some operations may be performed simultaneously or in a different order than shown in fig. 6, 7, and 8. Fig. 6 and 7 will be described together, and fig. 8 will be described in connection with fig. 6 and 7.

Referring to fig. 6, the method 600 begins at operation 602, in operation 602, a UE (e.g., receiving device 202) wakes up from a sleep mode and an OFDM symbol (e.g., OFDM symbol 304) including a payload (e.g., payload 306) and a CP (e.g., CP 308) is received by the UE. In some embodiments, transceiver 906 in fig. 9 may be configured to receive OFDM symbols.

The method 600 proceeds to operation at 604 where it is determined whether a CP is detected in operation at 604. If a CP is detected, the method 600 proceeds to operations at 608, 610, and 612, where in operations at 608, 610, and 612, an autocorrelation of the CP and payload of the OFDM symbol is performed, time and frequency corrections are performed based on one or more peaks of the autocorrelation, and data is processed based on the time and frequency corrections. As shown in fig. 2, CP-based time and frequency correction module 240 of receiving device 202 may perform an autocorrelation and time and frequency correction. The data processing module 250 of the receiving device 202 may perform data processing. Details of operations 608, 610, and 612 may be described in more detail in fig. 7.

For example, as shown in fig. 7, after performing the auto-correlation of the CP and the payload in operation at 608, in operation at 702, it is determined whether more than one peak above a predetermined threshold is detected. As shown in fig. 2, CP-based time and frequency correction module 240 of receiving device 202 may perform this determination.

In some embodiments, if only one peak above the threshold is detected, the method 600 proceeds to operation 610a, where time and frequency correction is performed based on the peak of the autocorrelation in operation 610 a. The method 600 then proceeds to operation 612a, where data (e.g., received OFDM symbols) is processed based on the time and frequency corrections in operation 612 a. As shown in fig. 2, the data processing module 250 of the receiving device 202 may perform data processing.

Referring back to operation 702, if more than one peak above the threshold is detected, the method 600 proceeds to operation at 704 where it is determined whether the time span between the more than one peak above the threshold is longer than the time span for the CP. If the time span between more than one peak above the threshold is not longer than the time span for the CP, the method 600 proceeds to operation at 610b where time and frequency correction is performed based on the earliest peak or strongest peak of the autocorrelation. The method 600 proceeds to operation 612a where the data is processed based on time and frequency corrections (e.g., adjusted time or frequency) in operation 612 a.

Referring back to operation 704, if the time span between more than one peak above the threshold is longer than the time span for the CP, the method 600 proceeds to operation at 706 where the received OFDM symbol is converted into copies according to the number of peaks above the threshold, the peaks being separated from each other by at least the time span of the CP. For example, if m peaks are detected above a threshold and separated from each other by at least the time span of the CP, the received OFDM symbol may be converted into m copies accordingly.

The method 600 then proceeds to operation 610c where time and frequency corrections are performed separately for each copy in operation 610 c. For example, the autocorrelation unit 244 may associate a CP with each replica separately, and the time and frequency correlation unit 246 may adjust the time or frequency of each replica based on each correlation result separately.

The method 600 then proceeds to operation at 612c, where each replica is processed based on the time and frequency corrections of the replica used to demodulate the OFDM symbol, and at least one demodulated raw data may be selected as output by the data processing module 250 in the receiving device 202 based on a metric (e.g., signal-to-noise ratio (SNR)) of the demodulated raw data. For example, the data processing module 250 may demodulate each copy separately and select one copy with the best quality (e.g., best SNR) as the output.

Referring back to the operation at 604 in fig. 6, if a valid CP is not detected, then in operation 606, the data may be processed using a default timing (e.g., without correcting time and/or frequency drift based on the CP).

In operation 614, activity for subsequent wakeups is determined. For example, a time and frequency correction method for a subsequent wakeup may be determined based on the time and frequency correction results of the current wakeup. For example, if no valid CP is detected, the SNR of the received data is less than a threshold, or the time or frequency drift is greater than the detection range of the CP-based time and frequency correction scheme disclosed herein, an alternative time and frequency correction scheme (e.g., a reference signal-based time and frequency correction scheme) may be selected for subsequent wakeups. In some embodiments, the point in time for subsequent wakeup (e.g., if additional wakeup periods are needed to receive the reference signal) may also be determined based on the selection of the time and frequency correction scheme for subsequent wakeup. As shown in fig. 2, the modules 240, 260, and 270 of the receiving device 202 operate in conjunction and may be configured to decide on activities for subsequent wakeups.

In operation 616, after processing the received data, the UE may enter a sleep mode again to reduce power consumption.

Fig. 8 illustrates a flowchart of an exemplary method 800 for wireless communication using additional steps in addition to method 600, according to some embodiments of the present disclosure.

Referring to fig. 8, a method 800 begins at operation 802, in operation 802, a UE (e.g., receiving device 202) wakes up from a sleep mode, and the UE receives OFDM symbols.

The method 800 proceeds to operation at 804 where it is determined whether CP-based time and frequency correction is enabled. For example, the UE may determine whether CP-based time and frequency correction is enabled based on an instruction from a last wakeup (e.g., an instruction generated in operation 614 of method 600). For example, if one or more of the following are detected in the last wake-up: 1) no valid CP is detected, 2) no peak above a threshold is detected, 3) SNR of the demodulated symbol (e.g., output of data processing module 250) is too low, 4) time or frequency drift is greater than the detection range of the CP-based time and frequency correction scheme, then the UE may indicate that CP-based time and frequency correction is not enabled for the current wake-up. If the CP-based time and frequency correction is not enabled, method 800 proceeds to operation at 806, where the time and frequency correction is performed using an alternative time and frequency correction (e.g., a method based on a reference signal such as PSS, SSS, CRS, or SSB) in operation at 806. As shown in fig. 2, the alternative time and frequency correction module 260 may perform time and frequency correction based on at least one of the reference signals described above.

If CP-based time and frequency correction is enabled, method 800 proceeds to operation 604 where the CP-based time and frequency correction is performed similar to the operations described in FIGS. 6 and 7 in operation 604. For clarity and simplicity, the same operations will not be described.

In method 800, when CP-based time and frequency correction is performed, the operations performed in method 600 are different. In operation 606', when a valid CP is not detected in the current wakeup in operation 604, the data may be processed based on the time and frequency adjusted according to the alternative time and frequency correction generated in operation 806, instead of processing the data using the default time. As shown in fig. 2, the data processing module 250 may demodulate the data based on the adjusted time.

In various aspects of the disclosure, the functions described herein may be implemented in hardware, software, firmware, or any combination thereof. If the functions are implemented in software, the functions may be stored on a non-transitory computer-readable medium as instructions or code, or encoded into instructions or code. Computer readable media includes computer storage media. A storage medium may be any available medium that can be accessed by a receiving device (e.g., receiving device 900 of fig. 9). By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, HDD, such as magnetic disk storage or other magnetic storage devices, flash drives, SSDs, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a processing system (e.g., a mobile device or computer). Disk and disc, as used herein, includes CD, laser disc, optical disc, DVD and floppy disk wherein the disk typically reproduces data magnetically and the disc reproduces data optically using a laser. Combinations of the above should also be included within the scope of computer-readable media.

According to one aspect of the disclosure, an apparatus is disclosed that includes at least one processor and a memory storing instructions. The instructions, when executed by the at least one processor, cause the apparatus to receive a symbol comprising a CP and a payload. The instructions, when executed by the at least one processor, further cause the apparatus to detect the CP and perform an autocorrelation of the CP and the payload. The instructions, when executed by the at least one processor, further cause the apparatus to adjust at least one of a time or a frequency of the received symbol based on a result of the autocorrelation.

In some embodiments, execution of the instructions further causes the apparatus to convert the adjusted symbols from the time domain to the frequency domain.

In some embodiments, execution of the instructions further causes the apparatus to demodulate the converted symbols based on at least one of the adjusted time or frequency.

In some embodiments, to detect that one or more peaks of the autocorrelation are above a threshold, execution of the instructions further causes the apparatus to detect one or more peaks of the autocorrelation that are above the threshold.

In some embodiments, execution of the instructions further cause the apparatus to adjust at least one of a time or frequency of the received symbol based on the one or more peaks.

In some embodiments, to adjust at least one of the time or frequency of the received symbol, execution of the instructions further causes the apparatus to detect that the plurality of peaks is above a threshold.

In some embodiments, execution of the instructions further causes the apparatus to determine whether the time span of the plurality of peaks is longer than the time span of the CP.

In some embodiments, to adjust at least one of the time or frequency of the received symbol, execution of the instructions further causes the apparatus to adjust at least one of the time or frequency of the received symbol based on at least one of an earliest peak or a strongest peak of the plurality of peaks in response to the time span of the plurality of peaks not being longer than the time span of the CP.

In some embodiments, to adjust at least one of the time or frequency of the received symbol, execution of the instructions further causes the apparatus to select at least some peaks from the plurality of peaks separated by at least a time span of the CP in response to the plurality of peaks having a time span longer than a time span of the CP.

In some embodiments, to adjust at least one of the time or frequency of the received symbol, execution of the instructions further causes the apparatus to convert the received symbol into multiple copies based on the selected peak.

In some embodiments, execution of the instructions further cause the apparatus to: adjusting at least one of time or frequency of each of the plurality of copies of the symbol, respectively; converting each copy of the symbol from the time domain to the frequency domain; demodulating each converted copy of the symbol based on at least one of the respective adjusted time or frequency; and selecting at least one of the demodulated copies of the symbol based on the metric of the demodulated copies of the symbol.

In some embodiments, execution of the instructions further cause the apparatus to determine whether a quality criterion is met based on the received symbol, and adjust at least one of a time or frequency of another symbol received in a next wakeup based on the determination.

In some embodiments, wherein the quality criteria includes an SNR of the received symbol being above a threshold.

In some embodiments, wherein the quality criterion comprises at least one peak of the autocorrelation being above a threshold.

In some embodiments, execution of the instructions further cause the apparatus to adjust at least one of a time or frequency of another symbol based on a result of automatic correction of another CP and another payload of another symbol received in a next wakeup in response to satisfaction of a quality criterion.

In some embodiments, execution of the instructions further cause the apparatus to adjust at least one of a time or frequency of another symbol based on the reference signal received in the next wakeup in response to not meeting the quality criterion.

In some embodiments, the reference signal comprises at least one of PSS, SSS, CRS or SSB.

In some embodiments, execution of the instructions further causes the apparatus to determine a point in time for starting an immediately subsequent wakeup based on the received symbol.

In some embodiments, the received symbols are OFDM symbols.

In some embodiments, at least one of the time or frequency has a drift caused by the apparatus being in sleep mode before receiving the symbol.

In some embodiments, at least one of the time or frequency of the received symbol is adjusted based on the end of the received symbol, the end of the received symbol being indicated by the result of the automatic correction.

In some embodiments, at least one of the time or frequency of the received symbols is adjusted based on the time and frequency of the symbols indicated by the result of the autocorrelation, in accordance with a sampling frequency used to demodulate the received signal.

In accordance with another aspect of the present disclosure, a baseband chip is disclosed that includes an interface and time and frequency correction circuitry operatively coupled to the interface. The interface is configured to receive an OFDM symbol including a CP and a payload. The time and frequency correction circuit is configured to detect the CP and to perform an autocorrelation of the CP and the payload. The time and frequency correction circuit is further configured to adjust at least one of a time or frequency of the received symbol based on a result of the autocorrelation.

In some embodiments, the baseband chip further comprises data processing circuitry configured to: converting the modulated symbols from the time domain to the frequency domain; and demodulating the converted symbols based on at least one of the adjusted time or frequency.

In some embodiments, the time and frequency correction circuit is an application specific integrated circuit ASIC.

According to yet another aspect of the present disclosure, a method for time and/or frequency correction is disclosed. A symbol including a CP and a payload is received. Detecting the CP and performing an autocorrelation of the CP and the payload. At least one of the time or frequency of the received symbol is adjusted based on the result of the autocorrelation.

In some embodiments, to adjust at least one of the time or frequency of the received symbol, one or more peaks of the autocorrelation that are above a threshold are detected, and at least one of the time or frequency of the received symbol is adjusted based on the one or more peaks.

In some embodiments, the modulated symbols are converted from the time domain to the frequency domain.

In some embodiments, the converted symbols are demodulated based on at least one of the adjusted time or frequency.

In some embodiments, a plurality of peaks is detected above a threshold, and a determination is made as to whether a time span of the plurality of peaks is longer than a time span of the CP.

In some embodiments, in response to the time span of the plurality of peaks being no longer than the time span of the CP, at least one of the time or frequency of the received symbol is adjusted based on at least one of the earliest peak or strongest peak of the plurality of peaks.

In some embodiments, in response to the time span of the plurality of peaks being longer than the time span of the CP, at least some of the plurality of peaks separated by at least the time span of the CP are selected, and the received symbol is converted to a plurality of copies based on the selected peaks.

In some embodiments, at least one of the time or frequency of each copy of the symbol is adjusted separately, and each copy of the symbol is converted from the time domain to the frequency domain based on the respective adjusted at least one of the time or frequency.

In some embodiments, each converted copy of the symbol is demodulated based on at least one of the adjusted time or frequency, and at least one demodulated copy of the symbol is selected based on a metric of the demodulated copy of the symbol.

In some embodiments, a determination is made based on the received symbol whether a quality criterion is met, and at least one of a time or frequency of another symbol received in a next wakeup is adjusted based on the determination.

In some embodiments, the quality criteria includes that the SNR of the received symbol is above a threshold.

In some embodiments, the quality criterion includes at least one peak of the autocorrelation being above a threshold.

In some embodiments, at least one of the time or frequency of the other symbol is adjusted based on the result of automatically correcting the other CP and the other payload of the other symbol received in the next wakeup in response to the quality criterion being met.

In some embodiments, at least one of the time or frequency of the other symbol is adjusted based on the reference signal received in the next wakeup in response to the quality criterion not being met.

In some embodiments, a point in time for starting an immediately subsequent wakeup is determined based on the received symbols.

In some embodiments, the received symbols are OFDM symbols.

In some embodiments, at least one of time or frequency has drift caused by the baseband chip being in sleep mode before receiving the symbol.

According to another aspect of the disclosure, a non-transitory computer-readable medium encoded with instructions that, when executed by at least one processor of a terminal device, perform a process is disclosed. The process comprises the following steps: a symbol including a CP and a payload is received. The process further includes: detecting the CP and performing an autocorrelation of the CP and the payload. The process further includes: at least one of the time or frequency of the received symbol is adjusted based on the result of the autocorrelation.

According to another aspect of the present disclosure, an apparatus for time and/or frequency correction is disclosed, the apparatus comprising a receiving module, a detecting module, an autocorrelation module, and a time or frequency correction module. The receiving module is configured to receive an OFDM symbol including a Cyclic Prefix (CP) and a payload. The detection module is configured to detect the CP. The autocorrelation module is configured to perform an autocorrelation of the CP and the payload. The time or frequency correction module is configured to adjust at least one of a time or frequency of the received symbol based on a result of the autocorrelation.

Thus, the foregoing description of the specific embodiments will reveal the general nature of the disclosure, which, by applying knowledge within the skill of the art, can readily modify and/or adapt for various applications such specific embodiments without undue experimentation, without departing from the general concept of the present disclosure. Accordingly, 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.

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. For ease of description, the boundaries of these functional building blocks are arbitrarily defined herein. Alternate boundaries may be defined so long as the specified functions and relationships thereof are appropriately performed.

As contemplated by the inventors, the summary and abstract sections may set forth one or more, but not all of the exemplary embodiments of the disclosure, and thus the summary and abstract sections are not intended to limit the disclosure and appended claims in any way.

Various functional blocks, modules, and steps have been described above. The particular arrangements provided are illustrative and not limiting. Accordingly, the functional blocks, modules, and steps may be reordered or combined in a different manner than the examples provided above. Similarly, certain embodiments include only a subset of the functional blocks, modules, and steps, and allow for any such subset.

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

Claims

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 to at least:

receiving a symbol including a cyclic prefix CP and a payload; wherein, before receiving the symbol,

at least one of time or frequency has drift caused by the device being in sleep mode;

detecting the CP;

performing an autocorrelation of the CP and the payload; and

adjusting at least one of time or frequency of the received symbol based on the result of the autocorrelation;

To detect one or more peaks of the autocorrelation that are above a threshold, execution of the instructions causes the apparatus to:

detecting that a plurality of peaks is above a threshold;

wherein execution of the instructions causes the apparatus to:

determining whether a time span of the plurality of peaks is longer than a time span of the CP;

wherein, to adjust at least one of a time or a frequency of the received symbol based on one or more peaks of the autocorrelation, execution of the instructions causes the apparatus to:

at least one of a time or a frequency of the received symbol is adjusted based on the plurality of peaks according to the determination.

2. The apparatus of claim 1, wherein execution of the instructions further causes the apparatus to:

converting the symbol from the time domain to the frequency domain; and

the converted symbols are demodulated based on at least one of the adjusted time or frequency.

3. The apparatus of claim 1, wherein to adjust at least one of a time or a frequency of the received symbol based on the plurality of peaks in accordance with the determination, execution of the instructions causes the apparatus to:

in response to the time span of the plurality of peaks not being longer than the time span of the CP, at least one of the time or frequency of the received symbol is adjusted based on at least one of the earliest peak or strongest peak of the plurality of peaks.

4. The apparatus of claim 2, wherein to adjust at least one of a time or a frequency of the received symbol based on the plurality of peaks in accordance with the determination, execution of the instructions further causes the apparatus to:

selecting at least some peaks from the plurality of peaks that are separated by at least the time span of the CP in response to the plurality of peaks having a longer time span than the time span of the CP;

converting the received symbol into a plurality of copies based on the selected peak value; and

at least one of a time or a frequency of each of the plurality of copies of the symbol is adjusted separately.

5. The apparatus of claim 4, wherein execution of the instructions causes the apparatus to:

converting each copy of the symbol from the time domain to the frequency domain;

demodulating each converted copy of the symbol based on at least one of a respective adjusted time or frequency; and

at least one of the demodulated copies of the symbol is selected based on a metric of the demodulated copies of the symbol.

6. The apparatus of any of claims 1-5, wherein execution of the instructions causes the apparatus to:

Determining whether a quality criterion is met based on the received symbols; and

at least one of a time or a frequency of another symbol received in a next wakeup is adjusted based on the determination.

7. The apparatus of claim 6, wherein the quality criteria comprises at least one of: the signal-to-noise ratio SNR of the received symbol is above a threshold or at least one peak of the autocorrelation is above a threshold.

8. The apparatus of claim 7, wherein to adjust at least one of a time or a frequency of another symbol received in a next wake-up, execution of the instructions causes the apparatus to:

in response to the quality criterion being met, at least one of a time or frequency of another symbol received in the next wakeup is adjusted based on a result of automatic correction of the other CP and the other payload of the other symbol.

9. The apparatus of claim 7, wherein to adjust at least one of a time or a frequency of another symbol received in the next wakeup, execution of the instructions causes the apparatus to:

in response to not meeting the quality criterion, at least one of a time or frequency of the other symbol is adjusted based on a reference signal received in the next wakeup.

10. The apparatus of claim 9, wherein the reference signal comprises at least one of a primary synchronization signal PSS, a secondary synchronization signal SSS, a common reference signal CRS, or a synchronization signal block SSB.

11. The apparatus of any one of claims 1-5, wherein execution of the instructions further causes the apparatus to:

a point in time for starting an immediately subsequent wakeup is determined based on the received symbols.

12. The apparatus of claim 11, wherein to determine a point in time for starting an immediately subsequent wakeup, execution of the instructions further causes the apparatus to:

determining whether a quality criterion is met;

in the event that it is determined that the quality criterion is met, waking up at a point in time at which reception of the symbol begins; and

in case it is determined that the quality criterion is not met, waking up at a point in time before the point in time at which reception of the symbol starts for receiving a reference signal for time and frequency correction.

13. The apparatus of claim 12, wherein to determine a point in time for starting an immediately subsequent wakeup, execution of the instructions causes the apparatus to:

at least one of the time or frequency of the received symbols is adjusted based on the time and frequency of the symbols indicated by the result of the autocorrelation in accordance with a sampling frequency used to demodulate the received signal.

14. A baseband chip, comprising:

an interface configured to receive an orthogonal frequency division multiplexing, OFDM, symbol; and

time and frequency correction circuitry operably coupled to the interface and configured to:

receiving the OFDM symbol including a cyclic prefix CP and a payload; wherein at least one of time or frequency has a drift caused by the baseband chip being in sleep mode prior to receiving the symbol;

detecting the CP;

performing an autocorrelation of the CP and the payload; and

detecting that a plurality of peaks is above a threshold;

15. The baseband chip of claim 14, further comprising data processing circuitry configured to:

converting the symbol from the time domain to the frequency domain; and

16. The baseband chip according to claim 14 or 15, wherein the time and frequency correction circuit is an application specific integrated circuit ASIC.

17. A method for time and/or frequency correction, comprising:

receiving a symbol including a cyclic prefix CP and a payload; wherein at least one of time or frequency has a drift caused by the baseband chip being in sleep mode prior to receiving the symbol;

detecting the CP;

performing an autocorrelation of the CP and the payload; and

it is detected that a plurality of peaks are above a threshold,

wherein the method further comprises:

wherein adjusting at least one of a time or a frequency of the received symbol based on one or more peaks of the autocorrelation comprises:

18. The method of claim 17, further comprising:

converting the adjusted symbol from the time domain to the frequency domain; and

19. The method of claim 17, wherein adjusting at least one of a time or a frequency of the received symbol based on the plurality of peaks in accordance with the determination comprises:

20. The method of claim 18, wherein adjusting at least one of a time or a frequency of the received symbol based on the plurality of peaks in accordance with the determination comprises:

selecting at least two peaks from the plurality of peaks separated by at least the time span of the CP in response to the time span of the plurality of peaks being longer than the time span of the CP;

21. The method of claim 20, the method comprising:

Converting each adjusted copy of the symbol from the time domain to the frequency domain;

22. The method of any of claims 17 to 21, further comprising:

23. The method of claim 22, wherein the quality criteria comprises: the signal-to-noise ratio SNR of the received symbol is above a threshold or at least one peak of the autocorrelation is above a threshold.

24. The method of claim 23, wherein adjusting at least one of a time or a frequency of another symbol received in a next wakeup further comprises:

25. The method of claim 23, wherein adjusting at least one of a time or a frequency of another symbol received in the next wakeup further comprises:

26. The method of claim 25, wherein the reference signal comprises at least one of a primary synchronization signal PSS, a secondary synchronization signal SSS, a common reference signal CRS, or a synchronization signal block SSB.

27. The method of any of claims 17 to 21, further comprising:

a point in time for starting an immediately subsequent wakeup is determined based on the quality of the received symbol.

28. The method of claim 27, wherein determining a point in time for starting an immediately subsequent wakeup further comprises:

determining whether a quality criterion is met;

waking up a baseband chip at a point in time when reception of the symbol is started, in a case where it is determined that the quality criterion is satisfied; and

29. The method of claim 28, wherein adjusting at least one of a time or a frequency of the received symbol comprises:

30. A non-transitory computer-readable medium encoded with instructions that, when executed by at least one processor of an apparatus, perform a process comprising:

receiving a symbol including a cyclic prefix CP and a payload; wherein at least one of time or frequency has a drift caused by the apparatus being in sleep mode prior to receiving the symbol;

detecting the CP;

performing an autocorrelation of the CP and the payload; and

detecting that a plurality of peaks is above a threshold;

31. An apparatus for time and/or frequency correction, comprising:

a receiving module configured to receive an OFDM symbol including a cyclic prefix CP and a payload; wherein at least one of time or frequency has a drift caused by the baseband chip being in sleep mode prior to receiving the symbol;

a detection module configured to detect the CP;

an autocorrelation module configured to perform an autocorrelation of the CP and the payload; and

a time or frequency correction module configured to adjust at least one of a time or frequency of the received symbol based on a result of the autocorrelation;

a detection module further configured to detect that the plurality of peaks is above a threshold;

determining whether a time span of the plurality of peaks is longer than a time span of the CP; at least one of a time or a frequency of the received symbol is adjusted based on the plurality of peaks according to the determination.