WO2022204260A1 - Multi-antenna techniques for bluetooth systems - Google Patents

Abstract

In an example, a method of Bluetooth® communication implemented on a primary device is disclosed. At least one of a two-dimensional (2D) frequency hopping pattern or a one-dimensional (ID) time series pattern of the primary device are obtained by a processor. A channel condition of a first channel and a second channel is predicted based, at least in part, on the at least one of the 2D frequency hopping pattern or the ID time series pattern by the processor. A first signal is transmitted over the first channel to an antenna of a secondary device of Bluetooth communication based on the channel condition by a first antenna. A second signal is transmitted over the second channel to the antenna of the secondary device based on the channel condition by a second antenna.

Description

MULTI- ANTENNA TECHNIQUES FOR BLUETOOTH SYSTEMS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority to U.S. Provisional Application No.

63/165,734 filed March 24, 2021, entitled “MULTI-ANTENNA TECHNIQUES FOR BLUETOOTH SYSTEMS,” which is hereby incorporated by reference in its entirety.

BACKGROUND

[0002] Embodiments of the present disclosure relate to apparatus and method for wireless communication, particularly, Bluetooth^® (BT) communication.

[0003] Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. A radio access technology (RAT) is the underlying physical connection method for a radio-based communication network. Many modem terminal devices, such as mobile devices, support several RATs in one device. A wireless personal area network (WPAN) is a personal, short-range wireless network for interconnecting devices centered around a specific distance from a user. WPANs have gained popularity because of the flexibility and connectivity convenience that WPANs provide. WPANs, such as those based on device-to-device communication protocols (e.g., a Bluetooth^® protocol, a Bluetooth^® Low Energy (BLE) protocol, a Zigbee^® protocol, etc.), provide wireless connectivity to peripheral devices by providing wireless links that allow connectivity within a specific distance (e.g., 5 meters, 10 meters, 20 meters, 100 meters, 1 kilometer etc.). SUMMARY

[0004] In one example, a primary device of BT communication includes a first antenna, a second antenna, a processor operatively coupled to the first and second antennas, and memory storing instructions. The first antenna is configured to communicate with an antenna of a secondary device of Bluetooth communication over a first channel. The second antenna is configured to communicate with the antenna of the secondary device over a second channel. Execution of the instructions causes the processor to obtain at least one of a two-dimensional (2D) frequency hopping pattern or a one-dimensional (ID) time series pattern of the primary device. Execution of the instructions also causes the processor to predict a channel condition of the first channel and the second channel based, at least in part, on the at least one of the 2D frequency hopping pattern or the ID time series pattern. Execution of the instructions further causes the processor to control the first antenna and the second antenna to transmit a first signal and a second signal over the first channel and the second channel, respectively, to the antenna of the secondary device based on the channel condition.

[0005] In another example, a method of BT communication implemented on a primary device is disclosed. At least one of a 2D frequency hopping pattern or a ID time series pattern of the primary device are obtained by a processor. A channel condition of a first channel and a second channel is predicted based, at least in part, on the at least one of the 2D frequency hopping pattern or the ID time series pattern by the processor. A first signal is transmitted over the first channel to an antenna of a secondary device of Bluetooth communication based on the channel condition by a first antenna. A second signal is transmitted over the second channel to the antenna of the secondary device based on the channel condition by a second antenna.

[0006] In still another example, a system of BT communication includes a primary device and a secondary device. The primary device includes a first antenna, a second antenna, a processor operatively coupled to the first and second antennas, and memory storing instructions. The first antenna is configured to communicate with an antenna of the secondary device over a first channel. The second antenna is configured to communicate with the antenna of the secondary device over a second channel. Execution of the instructions causes the processor to encode a first signal and a second signal using space-time block coding (STBC), and control the first antenna and the second antenna to transmit the encoded first signal and the encoded second signal over the first channel and the second channel, respectively. The secondary device includes the antenna, a processor operatively coupled to the antenna, and memory storing instructions. The antenna is configured to receive the encoded first signal and the encoded second signal over the first channel and the second channel from the first antenna and the second antenna of the primary device, respectively. Execution of the instructions causes the processor to estimate a channel condition of the first channel and the second channel based, at least in part, on the encoded first signal and the encoded second signal, and provide the channel condition to the primary device.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] 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.

[0008] FIG. 1 illustrates an exemplary BT network, according to some embodiments of the present disclosure.

[0009] FIG. 2 illustrates a block diagram of an exemplary node, according to some embodiments of the present disclosure.

[0010] FIG. 3 illustrates an exemplary multi-antenna BT communication system, according to some embodiments of the present disclosure.

[0011] FIG. 4 illustrates a block diagram of an exemplary BT primary device, according to some embodiments of the present disclosure.

[0012] FIG. 5 illustrates a block diagram of an exemplary BT secondary device, according to some embodiments of the present disclosure.

[0013] FIG. 6 illustrates an exemplary multi-antenna BT communication scheme, according to some embodiments of the present disclosure.

[0014] FIG. 7A illustrates an exemplary BT frequency hopping scheme, according to some embodiments of the present disclosure.

[0015] FIG. 7B illustrates another exemplary BT frequency hopping scheme, according to some embodiments of the present disclosure.

[0016] FIG. 8 illustrates a block diagram of an exemplary channel prediction system for a

BT primary device, according to some embodiments of the present disclosure.

[0017] FIG. 9 illustrates an exemplary cloud-based model training system for a BT primary device, according to some embodiments of the present disclosure.

[0018] FIG. 10 illustrates an angle of arrival (AoA) or an angle of departure (AoD) of two antennas of an exemplary BT primary device, according to some embodiments of the present disclosure.

[0019] FIG. 11 illustrates a flow chart of an exemplary method of BT communication, according to some embodiments of the present disclosure.

[0020] FIG. 12 illustrates another exemplary multi-antenna BT communication scheme, according to some embodiments of the present disclosure.

[0021] FIG. 13 illustrates a flow chart of another exemplary method of BT communication, according to some embodiments of the present disclosure.

[0022] FIG. 14 illustrates still another exemplary multi-antenna BT communication scheme, according to some embodiments of the present disclosure.

[0023] FIG. 15 illustrates exemplary symbol structures of STBC used by a BT primary device, according to some embodiments of the present disclosure.

[0024] FIG. 16 illustrates an exemplary STBC scheme in multi-antenna BT communication, according to some embodiments of the present disclosure.

[0025] FIGs. 17A and 17B illustrate flow charts of another exemplary method of BT communication, according to some embodiments of the present disclosure.

[0026] Embodiments of the present disclosure will be described with reference to the accompanying drawings

DETAILED DESCRIPTION

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] BT is a short-range, device-to-device wireless communication protocol/standard that supports a WPAN between a primary device (a.k.a, a master device or a central device) and at least one secondary device (e.g., a slave device or a peripheral device). BT includes the Bluetooth^® Classic radio (a.k.a., Bluetooth Basic Rate/Enhanced Data Rate (BR/EDR)), which is a low power radio that streams data over 79 channels with 1 MHz spacing in the 2.4 GHz unlicensed industrial, scientific, and medical (ISM) frequency band, as well as the Bluetooth^® Low Energy (BLE) radio, which is designed for very low power operation over 40 channels with 2 MHz spacing in the 2.4 GHz unlicensed ISM frequency band.

[0032] On the other hand, multi-antenna techniques, such as diversity techniques, are employed to make a communication system robust and reliable even over varying channel conditions. Diversity techniques exploit the channel variations rather than mitigate them. Diversity techniques combat fading and interference by presenting the receiver with multiple uncorrelated copies of the same information-bearing signal. Essentially, diversity techniques are aimed at creating uncorrelated random channels - uncorrelated copies of the same signal (may also be in combined form) at the receiver front end. Combining techniques are employed at the receiver to exploit multipath propagation characteristics of a channel. However, BT was not initially designed for multi-antenna techniques and thus, does not support multi-antenna techniques very well.

[0033] Various embodiments in accordance with the present disclosure provide various schemes of BT communication that support multi-antenna techniques to enhance link budget while still being fully or largely compatible with the existing BT standards. As a result, the BT communication can become more reliable, for example, more robust under fading environments, and the distances for reliable BT communication can be increased.

[0034] FIG. 1 illustrates an exemplary BT 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, within BT network 100, a primary device 102 (a.k.a, a master device or a central device) may connect to and establish a BT communication link 116 with one or more secondary devices 104, 106, 108, 110, 112, 114 (e g , a slave device or a peripheral device) using a BL protocol, such as a BT Classic protocol, a BLE protocol, or a modified BLE protocol. The BL protocol is part of the BT core specification and enables radio frequency communication operating within the globally accepted 2.4 GHz ISM band.

[0035] Primary device 102 may include suitable logic, circuitry, interfaces, processors, and/or code that may be used to communicate with one or more secondary devices 104, 106, 108, 110, 112, and 114 using the BL protocol as described below. Primary device 102 may operate as an initiator to request the establishment of a link layer (LL) connection with an intended secondary device 104, 106, 108, 110, 112, or 114.

[0036] After a requested LL connection is established, primary device 102 may become a master device, and intended secondary device 104, 106, 108, 110, 112, or 114 may become a slave device for the established LL connection. As a master device, primary device 102 may be capable of supporting multiple LL connections at a time with various secondary 104, 106, 108, 110, 112, and 114 (slave devices). Primary device 102 (master device) may be operable to manage various aspects of data packet communication in a LL connection with an associated secondary device 104, 106, 108, 110, 112, or 114 (slave device). For example, primary device 102 may be operable to determine an operation schedule in the LL connection with a secondary device 104, 106, 108, 110, 112, or 114. Primary device 102 may be operable to initiate a LL protocol data unit (PDU) exchange sequence over the LL connection. LL connections may be configured to run periodic connection events in dedicated data channels. The exchange of LL data PDU transmissions between primary device 102 and one or more of secondary devices 104, 106, 108, 110, 112, and 114 may take place within connection events.

[0037] In a connection event, primary device 102 may transmit signals (e.g., data signals) first to secondary device 104, 106, 108, 110, 112, or 114, and then receive signals (e.g., data signals) from secondary device 104, 106, 108, 110, 112, or 114; or primary device 102 may receive signals (e.g., data signals) first from secondary device 104, 106, 108, 110, 112, or 114, and then transmit signals (e.g., data signals) to secondary device 104, 106, 108, 110, 112, or 114. For example, in certain configurations, primary device 102 may be configured to transmit the first LL data PDU in each connection event to an intended secondary device 104, 106, 108, 110, 112, or 114. In certain other configurations, primary device 102 may utilize a polling scheme to poll intended secondary device 104, 106, 108, 110, 112, or 114 for a LL data PDU transmission during a connection event. Intended secondary device 104, 106, 108, 110, 112, or 114 may transmit a LL data PDU upon receipt of packet LL data PDU from primary device 102. In certain other configurations, a secondary device 104, 106, 108, 110, 112, or 114 may transmit a LL data PDU to primary device 102 without first receiving a LL data PDU from primary device 102.

[0038] Examples of primary device may include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a mobile station (STA), a laptop, a personal computer (PC), a desktop computer, a personal digital assistant (PDA), a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., MP3 player), a camera, a game console, a tablet, a smart device, a wearable device (e.g., smart watch, wireless headphones, etc.), a vehicle, an electric meter, a gas pump, a toaster, a thermostat, a hearing aid, a blood glucose on- body unit, an Internet-of-Things (IoT) device, or any other similarly functioning device.

[0039] Examples of secondary devices 104, 106, 108, 110, 112, and 114 may include a cellular phone, a smart phone, a SIP phone, a STA, a laptop, a PC, a desktop computer, a PDA, a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., MP3 player), a camera, a game console, a tablet, a smart device, a wearable device (e.g., smart watch, wireless headphones, etc.), a vehicle, an electric meter, a gas pump, a toaster, a thermostat, a hearing aid, a blood glucose on-body unit, an IoT device, or any other similarly functioning device. Although primary device 102 is illustrated in communication with six secondary devices 104, 106, 108, 110, 112, and 114 in BT network 100, primary device 102 may communicate with more or fewer than six peripheral devices within BT network 100 without departing from the scope of the present disclosure.

[0040] Primary device 102 may further communicate with other devices using any other suitable RATs, such as Wi-Fi, ZigBee, or cellular (e.g., global system for mobile communications (GSM), Long-Term Evolution (LTE), or New Radio (NR). For example, as shown in FIG. 1, primary device 102 may communicate with a remote device 120 (e.g., a cloud server) outside of BT network 100 through a long-rate communication link 122 of one or more local area networks (LANs) and wide area networks (WANs), such as a Wi-Fi network, a cellular network, or Internet, as opposed to a personal area network (PAN), such as BT network 100. [0041] As described below in detail, in some embodiments, multi-antenna BT communication can be established between primary device 102 and any secondary device 104, 106, 108, 110, 112, or 114 in BT network 100 Consistent with the scope of the present disclosure, primary device 104 may include multiple antennas, and intended secondary device 104, 106, 108, 110, 112, or 114 may include a single antenna, i.e., in an N×1 configuration, where /Vis a positive integer greater than 1.

[0042] In some embodiments, in certain configurations in which primary device 102 transmits data to secondary device 104, 106, 108, 110, 112, or 114 first in a connection event, primary device 102 may first predict the channel condition of the N×1 channels in BT communication link 116, such as the phase difference between the N×1 channels based on a 2D frequency hopping pattern and/or a ID time series pattern of primary device 102. Primary device 102 then may transmit the signals from the multiple antennas to the single antenna of secondary device 104, 106, 108, 110, 112, or 114 over the N× 1 channels based on the predicted channel condition, for example, using beamforming techniques.

[0043] In some embodiments, in certain configurations in which primary device 102 receives data from secondary device 104, 106, 108, 110, 112, or 114 first in a connection event, primary device 102 may additionally or alternatively predict the channel condition of the N×1 channels in BT communication link 116, such as the phase difference, based on the signals received from secondary device 104, 106, 108, 110, 112, or 114 over the N× 11 channels.

[0044] In some embodiments, in certain configurations in which primary device 102 transmits data to secondary device 104, 106, 108, 110, 112, or 114 first in a connection event, primary device 102 may encode the signals using STBC and transmit the STBC encoded signals from the multiple antennas of primary device 102, for example, in a broadcasting mode to secondary devices 104, 106, 108, 110, 112, and 114. Secondary device 104, 106, 108, 110, 112, or 114 may receive the STBC encoded signals from the single antenna thereof over the Axl channels, and estimate the channel condition of the N×1 channels based on the STBC encoded signals. Secondary device 104, 106, 108, 110, 112, or 114 may further provide the estimated channel condition to primary device 102, for example, for future transmission.

[0045] Each of the elements of BT network 100 of FIG. 1 may be considered a node of BT network 100. More detail regarding the possible implementation of a node is provided by way of example in the description of a node 200 in FIG. 2. Node 200 may be configured as primary device 102 or secondary device 104, 106, 108, 110, 112, or 114 in FIG. 1. Similarly, node 200 may also be configured as remote device 120 in FIG. 1. As shown in FIG. 2, node 200 may include a processor 202, a memory 204, and a transceiver 206. These components are shown as connected to one another by a bus, but other connection types are also permitted When node 200 is primary device 102 or secondary device 104, 106, 108, 110, 112, or 114, additional components may also be included, such as a user interface (UI), sensors, and the like. Similarly, node 200 may be implemented as a blade in a server system when node 200 is configured as remote device 120. Other implementations are also possible.

[0046] Transceiver 206 may include any suitable device for sending and/or receiving data, such as a BT transceiver. Node 200 may include one or more transceivers, although only one transceiver 206 is shown for simplicity of illustration. An antenna 208 is shown as a possible communication mechanism for node 200. Multiple antennas and/or arrays of antennas may be utilized for multi-antenna BT communication. Other communication hardware, such as a network interface card (NIC), may be included as well.

[0047] As shown in FIG. 2, node 200 may include processor 202. Although only one processor is shown, it is understood that multiple processors can be included. Processor 202 may include microprocessors, microcontrollers (MCUs), 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 202 may be a hardware device having one or many processing cores. Processor 202 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.

[0048] As shown in FIG. 2, node 200 may also include memory 204. Although only one memory is shown, it is understood that multiple memories can be included. Memory 204 can broadly include both memory and storage. For example, memory 204 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 202. Broadly, memory 204 may be embodied by any computer-readable medium, such as a non-transitory computer-readable medium.

[0049] Processor 202, memory 204, and transceiver 206 may be implemented in various forms in node 200 for performing multi-antenna BT communication functions. In some embodiments, processor 202, memory 204, and transceiver 206 of node 200 are implemented (e.g., integrated) on one or more system-on-chips (SoCs). In one example, processor 202 and memory 204 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 202 and memory 204 may be integrated on a BT SoC (also referred to herein as a “BT chip”) that converts the raw data, e.g., from the host chip, to signals that can be used to modulate the carrier frequency forBT transmission, and vice versa, which can run a real-time operating system (RTOS). In still another example, processor 202 and transceiver 206 (and memory 204 in some cases) may be integrated on a radio frequency (RF) SoC (sometimes known as a “transceiver,” referred to herein as an “RF chip”) that transmits and receives RF signals with antenna 208. It is understood that in some examples, some or all of the host chip, BT chip, and RF chip may be integrated as a single SoC. For example, a BT chip and an RF chip may be integrated into a single SoC that manages all the radio functions for BT communication.

[0050] Various aspects of the present disclosure related to multi-antenna BT communication may be implemented as software and/or firmware elements executed by a generic processor in a BT chip (e.g., a BT processor) and/or a generic processor in a host chip (e.g., a CPU). 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 ASICs.

[0051] FIG. 3 illustrates an exemplary multi-antenna BT communication system 300, according to some embodiments of the present disclosure. Multi-antenna BT communication system 300 may be used between suitable nodes in BT network 100. As shown in FIG. 3, multi antenna BT communication system 300 may include a primary device 302 including N antennas (e.g., including a first antenna Anti and a second antenna Ant 2), a secondary device 304 including a single antenna (e.g., antenna Ant), and N' 1 channels 306. For example, primary device 302 may be an example of primary device 102 of BT network 100, and secondary device 304 may be an example of secondary device 104, 106, 108, 110, 112, or 114 of BT network 100 in FIG. 1. Channels 306 may be an example of BT communication link 116 of BT network 100 in FIG. 1, e.g., a multipath communication link between the A antennas of primary device 302 and the single antenna of secondary device 304. Multi-antenna BT communication system 300 may be used for increasing the BT data transmission rate between primary device 302 and secondary device 304 over Axl channels 306. Both primary device 302 and secondary device 304 may include a processor, a memory, and a transceiver, which may be examples of processor 202, memory 204, and transceiver 206 described above in detail, respectively, with respect to FIG. 2.

[0052] For example, FIG. 4 illustrates a block diagram of primary device 302, according to some embodiments of the present disclosure, and FIG. 5 illustrates a block diagram of secondary device 304, according to some embodiments of the present disclosure. As shown in FIG. 4, primary device may include a BT chip 402, a host chip 406, multiple antennas 410, and antenna switches 411. In some embodiments, BT chip 402 is implemented by processor 202, memory 204, and transceiver 206, as described above with respect to FIG. 2. Besides on-chip memory 413 and 412 (also known as “internal memory,” e.g., as registers, buffers, or caches) on each chip 406 or 402, primary device 302 may further include a system memory 408 (a.k.a. the main memory) that can be shared by each chip 402 and 406 through the main bus. Although BT chip 402 is illustrated as a standalone SoC that includes the function of an RF chip, it is understood that in one example, BT chip 402 and an RF chip (including a transmitter 416 (TX) and a receiver 418 (RX)) may be separated into two chips; in another example, BT chip 402 and host chip 406 may be integrated as one SoC.

[0053] In the uplink, a processor 407 of host chip 406 may generate original data and send it to BT chip 402 for encoding, modulation, and mapping. BT chip 402 may access the original data from host chip 406 directly using an interface 414 (I/F) or through system memory 408 and then perform uplink functions, such as channel coding and interleaving, modulation, symbol mapping, and layer mapping and precoding. BT chip 402 then may use transmitter 416 to convert the modulated signals in the digital form from BT chip 402 into analog signals, i.e., RF signals, and transmit the RF signals in multiple signal streams through multiple antennas 410, respectively, into Nx 1 channels 306. Consistent with the scope of the present disclosure, in some embodiments, processor 407 of host chip 406 may obtain and send additional data (not to be transmitted) to BT chip 402 to assist BT chip 402 to perform its uplink functions, such as models or parameters thereof for multi-channel estimation (e.g., predicting the channel condition of N×1 channels 306), as described below in detail. In some embodiments, processor 407 of host chip 406 may train models or parameters thereof for multi-channel estimation (e.g., predicting the channel condition of N×1 channels 306). In some embodiments, processor 407 of host chip 406 may receive models or parameters thereof for multi-channel estimation (e.g., predicting the channel condition of N×1 channels 306) from another device, such as remote device 120 in FIG. 1. In some embodiments, one TX/RX 416/148 chain may be connected to one antenna 410, and antenna switches 411 may be used for TX/RX 416/418 switching

[0054] In the downlink, multiple antennas 410 may receive the RF signals in the multiple transmitted signal streams through N×1 channels 306 and pass the RF signals to receiver 418 of BT chip 402 to perform any suitable front-end RF functions, such as filtering, down-conversion, or sample-rate conversion, and convert the RF signals into low-frequency digital signals. BT chip 402 then may perform downlink functions, such as de-precoding, multi-channel detection, demapping, and channel decoding. The original data may be extracted by BT chip 402 and passed to host chip 406 through interface 414 or stored into system memory 408.

[0055] As shown in FIG. 5, secondary device 304 may include a BT chip 502 and a single antenna 510. In some embodiments, BT chip 502 is implemented by processor 202, memory 204, and transceiver 206, as described above with respect to FIG. 2. BT chip 502 may include an on- chip memory 512 (also known as “internal memory,” e.g., as registers, buffers, or caches) and a processor 520. Although BT chip 502 is illustrated as a standalone SoC that includes the function of an RF chip, it is understood that in one example, BT chip 502 and an RF chip (including a transmitter 516 (TX) and a receiver 518 (RX)) may be separated into two chips; in another example, BT chip 502 and host chip 406 may be integrated as one SoC. Although not shown in FIG. 5, it is understood that in some examples, secondary device 304 may also include a host chip as described above in detail. Although not shown in FIG. 5, it is also understood that in some examples, secondary device 304 may also include an antenna switch, like antenna switch 411 in FIG. 4.

[0056] In the uplink, BT chip 502 may perform uplink functions, such as channel coding and interleaving, modulation, symbol mapping, layer mapping, and precoding. BT chip 502 then may use transmitter 516 to convert the modulated signals in the digital form from BT chip 502 into analog signals, i.e., RF signals, and transmit the RF signals in multiple signal streams through antenna 510, respectively, into N×1 channels 306. In the downlink, antenna 510 may receive the RF signals in the multiple transmitted signal streams through N-' 1 channels 306 and pass the RF signals to receiver 518 of BT chip 502 to perform any suitable front-end RF functions, such as filtering, down-conversion, or sample-rate conversion, and convert the RF signals into low- frequency digital signals. BT chip 502 then may perform downlink functions, such as deprecoding, multi-channel detection, de-mapping, and channel decoding.

[0057] Referring back to FIG. 3, depending on whether a device is transmitting or receiving data at a particular moment, primary device 302 and secondary device 304 may act as a transmitting device or a receiving device at different times, i.e., switching their roles. The transmitting device may process the original data (e.g., process the input bits using various uplink functions) and may transmit the processed data (e.g., the encoded symbols) in multiple signal streams to the receiving device through N×1 channels 306. The receiving device may receive the multiple transmitted signal streams and detect the original data (e.g., the decoded bits) using various downlink functions. [0058] As illustrated in FIG. 3, without loss of generality and for simplicity, N = 2 (i.e., two antennas of primary device 302 and 2><1 channels 306) is assumed and used as the example for describing multi-antenna BT communication system 300 in the present disclosure. It is understood that N can be any suitable positive integer greater than 1 in other examples. When primary device 302 works as the receiving device and secondary device 304 works as the transmitting device, the first and second RX signals received by the first and second antenna Anti and Ant 2 of primary device 302 at time t can be represented as:

where s_a(t) represents the TX signal transmitted from the antenna Ant of secondary device 304, hi(f, t) and h2( f, t) represent the two channels gains between Ant and Ant 1 and between Ant and Ant 2, respectively, at frequency /used for BT communication, n_p,1(t) and §_p,1(t) represent the noises over the two channels between Ant and Ant 1 and between Ant and Ant 2, respectively, and r_p,1(t) and r_p,2(t) represent the RX signals received by the first and second antenna Anti and Ant 2 of primary device 302, respectively. The signal-to-noise ratio (SNR) per chain is:

where E represents the expected value, s represents standard deviation, the reciprocal air- propagation fading channels h₁(f, t) and h₂(f, t) are modeled as slowly timing-varying and frequency-dependent complex numbers due to the very short distance between primary and secondary devices 302 and 304.

[0059] If maximal radio combining (MRC) technique is applied, for primary device 302 working as the receiving device, the MRC combined receiving signal r_p,MRC(t) is:

and the SNR becomes:

Compared to a single antenna system, MRC (with two antennas) may provide 3 to 10+ dB gain for the receiving device. In general, an MRC receiving device with N antennas would provide at least 10xlogl0(N) dB gains. The L' is also called diversity order. Normally severer fading would lead to bigger gains.

[0060] If equal gain combining (EGC) technique is applied, for primary device 302 working as the receiving device, the EGC combined receiving signal is:

where z is the angle of the complex number of

or

, and the SNR becomes

The simplest diversity scheme would be antenna selection diversity (SD), i.e., choosing the best antenna. Compared with the MRC technique, the EGC technique is simpler but with slight performance degradation.

[0061] When primary device 302 works as the receiving device and secondary device 304 works as the transmitting device, the RX signal received by antenna Ant of secondary device 304 at time t can be represented as:

[0062] If the channel condition of channels hi and h2 is known, primary device 302 (as transmitting device) can perform beamforming (precoding) as:

where z is the angle of the complex number of h)(f, t) or h₂if, t). Then the RX signal received by antenna Ant of secondary device 304 at time t can be represented as:

[0063] Equation (8) is very similar to Equation (6) of the EGC technique, which is not as good performance as the MRC technique. This observation may imply that links from primary device 302 (as transmitting device) to secondary device 304 (as receiving device) are not as good as the links from secondary device 304 (as transmitting device) to primary device 302 (as receiving device), providing everything else is the same. Assuming the total transmission power is the same (regardless of one or two antennas) at the primary device 302 side, the link budget could be improved by 3 to 10+ dBs. Normally severer fading would lead to bigger gains.

[0064] In order to enable primary device 302 (as transmitting device) to perform beamforming when transmitting data to secondary device 304 (as receiving device), primary device 302 needs to have knowledge of air-propagation channels (e.g., the channel condition of hi and h2). In some embodiments, to achieve constructive interference, as opposed to destructive interference, of multiple signals transmitted from multiple antennas (e.g., Ant 1 and Ant 2) of primary device 302 when arriving at the single antenna (e.g., Ant) of secondary device 304, one of the channel conditions that needs to be known by primary device 302 (as transmitting device) is the phase difference between the multiple channels. For example, when N = 2:

where ø(f,t) represents the phase difference between two reciprocal air-propagation fading channels hi and h2 (each modeled as a slowly timing (t)- varying and frequency (f)-dependent complex number) at frequency / and time t. Consistent with the scope of the present disclosure, various multi-antenna BT communication schemes are described below in detail, when used individually or in any suitable combinations under different scenarios or applications, can enable primary device 302 to obtain the channel condition, such as the phase difference, thereby performing beamforming when acting as the transmitting device, to improve the link budget. [0065] FIG. 6 illustrates an exemplary multi-antenna BT communication scheme, according to some embodiments of the present disclosure. As shown in FIG. 6, in a connection event, primary device 302 may act as the transmitting device first at stage 604 and then switch to the receiving device at stage 606, while secondary device 304 may act as the receiving device first at stage 604 and then switch to the transmitting device at stage 606. In other words, primary device 302 acts as the master device, while secondary device 304 acts as the slave device in this connection event. As a result, primary device 302 cannot determine the channel condition based on any signal received from secondary device 304 prior to stage 604 when primary device 302 starts to transmit data to secondary device 304 since primary device 302 starts as the transmitting device first in the connection event. Thus, at stage 602, primary device 302 may first perform channel prediction to predict the channel condition, such as the phase difference of the first and second channels hi and h2, based on information other than signals received from secondary device 304, such as 2D frequency hopping patterns and/or ID time series patterns of primary device 302.

[0066] BT systems, such as multi-antenna BT communication system 300, use frequency hopping, which changes (“hops”) the carrier frequency among distinct frequencies occupying a spectral band, in order to avoid interference and/or prevent eavesdropping. For example, as shown in FIG. 7, due to the use of frequency hopping and various power-saving techniques, it looks like a BT system is choosing random grid points to communicate between primary and secondary devices. Those random grid points may be collectively viewed as a “2D frequency hopping pattern” spanning in both the time (/) dimension and the frequency if) dimension. However, under the BT standards, the grid points are randomly distributed in both dimensions. In other words, the 2D frequency hopping pattern may include a random set of frequencies and a plurality of randomly spaced time points. Thus, it becomes very challenging for primary device 302 at / = 0 (i.e., the current time) to predict or extrapolate the channels accurately from the channel conditions in the past (i.e., between t = - k to t = -1), especially when the sampling of the 2D frequency hopping pattern does not meet 2D Nyquist criteria.

[0067] In some embodiments, primary device 302 at stage 602 may be configured to obtain a 2D frequency hopping pattern thereof in the past, and predict a channel condition of the first channel hi and the second channel h2 based, at least in part, on the 2D frequency hopping pattern. The channel condition may include a phase difference between the first channel hi and the second channel h2. FIG. 8 illustrates a block diagram of an exemplary channel prediction system 820 for a BT primary device, such as primary device 302, according to some embodiments of the present disclosure. Channel prediction system 820 may be implemented by one or more processors of the BT primary device, such as processor 407 on host chip 406 and/or processor 420 on BT chip 402 of primary device 302.

[0068] In some embodiments, channel prediction system 820 includes a channel prediction module 812 configured to generate a prediction result 816, such as the channel condition (e.g., including the phase difference) based on a pattern 814, such as the 2D frequency hopping pattern of the BT primary device using a model 810. Model 810 may include any suitable models that can predict, interpolate, or extrapolate the current or future channel condition based on the history information of the channel, including but not limited to, bilinear interpolation, bicubic interpolation, linear interpolation, polynomial interpolation, spline interpolation, linear extrapolation, polynomial extrapolation, conic extrapolation, French curve extrapolation, etc. In some embodiments, model 810 may be a machine learning model, such as regression, support vector machine (SVM), decision tree, Bayesian network, artificial neural network (ANN), etc. [0069] Optionally, if model 810 is a machine learning model, model 810 may be trained by a model training system 830, as shown in FIG. 8. Model training system 830 may include a model training module 802 configured to train model 810 over a set of training samples 804 based on a loss function 806 using a training algorithm 808. In some embodiments, training samples 804 may be represented as where

represent the ground truth (GT), i.e., the actual

result, of the phase difference, which is known, just a moment later, and Φ

represents the corresponding predicted phase difference, which is predicted based on a corresponding 2D frequency hopping pattern, such that the training may be supervised training.

[0070] Model 810 may include a plurality of parameters that can be jointly adjusted by model training module 802 when being fed with training samples 804. Model training module 802 may jointly adjust the parameters of model 810 to minimize loss function 806 overtraining samples 804 using training algorithm 808. Training algorithm 808 may be any suitable iterative optimization algorithm for finding the minimum of loss function 806, including gradient descent algorithms (e g., the stochastic gradient descent algorithm). In some embodiments, model 810 g may be represented as:

including a plurality of parameters that can be tuned, where .v represents a particular 2D frequency hopping pattern that includes time points , and the

corresponding frequencies . In some embodiments, for each training sample

804, model training module 802 is configured to predict phase difference based on the

corresponding 2D frequency hopping pattern using model 810

g_s , and further configured to train model 810 g_s based on the difference between predicted

and GT phase difference Vj using loss function 806 with a goal for finding the minimum of loss function 806. That is, the loss between predicted

and GT phase difference Vj may be calculated and minimized, thereby training and optimizing model 810 g·. [0071] Model training system 830 can be implemented on a remote device, instead of the

BT primary device, because the remote device may be more powerful in computation and/or may collect more training sample sets 804 from a large number of BT primary devices, as opposed to as to a single BT primary device. That is, a machine learning model may be trained at a remote device and received from the remote device by a BT primary device for channel prediction. For example, as shown in FIG. 9, model training system 830 may be implemented on a remote device 901 (e.g., a cloud server) communicating with a plurality of BT primary devices 902. Remote device 901 may be one example of remote device 120 in FIG. 1, and BT primary device 902 may be one example of primary device 102 in FIG. 1 or primary device 302 in FIG. 3. In some embodiments, each BT primary device 902 may transmit its training sample set 804 (e.g., to remote device 901 periodically, continuously, and/or upon request. Remote

device 901 may update model 810 periodically, continuously, and/or upon request based on the received training sample sets 804. On the other hand, each BT primary device 902 may retrieve and receive updated model 810 periodically, continuously, and/or upon request from remote device 901.

[0072] Referring back to FIG. 8, to facilitate channel prediction performed by channel prediction system 820, in some embodiments, frequency hopping performed by primary device 302 may be controlled such that the randomness in the frequency dimension, the time dimension, or both may be reduced. Thus, in some embodiments, the 2D frequency hopping pattern may include a predetermined small set of frequencies in a very close neighborhood, as opposed to the entire set of all suitable frequencies. In other words, the frequency can only hop between a limited number of predetermined frequencies, for example, three uniformly spaced frequencies. For example, as shown in FIG. 7B, each dashed box represents that frequency hopping may be confined by a limited number of frequencies and time duration therein, such that the 2D frequency hopping pattern can also be limited by the dashed box, thereby simplifying the channel prediction based on the simplified 2D frequency hopping patterns. The number of the frequencies and the time duration in each frequency hopping confining box of FIG. 7B may be preset and/or adjusted based on various factors. In some embodiments, the time duration may be determined based on the rate at which the channel conditions change, i.e., how fast the conditions of the reciprocal air-propagation fading channels change. The time duration in a frequency hopping confining box may be decreased as the rate at which the channel conditions change increases and vice versa. For example, the time duration may be longer when the BT primary and secondary devices are stationary compared with the situation in which the BT primary and secondary devices are moving. In some embodiments, the number of frequencies may be determined based on the frequency response of the reciprocal air-propagation fading channels, i.e., the number of frequencies at which the multiple channels have the same condition. The number of frequencies in a frequency hopping confining box may be increased as the frequency response increases and vice versa. Moreover, the number of frequencies in a frequency hopping confining box may also affect the efficiency of channel prediction as the larger the number of frequencies is, the longer time the training and/or prediction may take. On the other hand, the number of frequencies in a frequency hopping confining box may further affect the effectiveness of BT frequency hopping, e g., interference reduction and eavesdropping prevention, and may increase the risk of violating the existing BT standards. In one example, frequency hopping confining box of FIG. 7B may include three frequencies in 0.5 seconds. In another example, frequency hopping confining box of FIG. 7B may include five frequencies in 1 second.

[0073] In some embodiments, the 2D frequency hopping pattern may include a plurality of uniformly spaced time points, as opposed to randomly spaced time points. In other words, the time interval between adjacent time points may be the same (and predetermined in some examples). In some embodiments, the 2D frequency hopping pattern may include a predetermined set of frequencies and a plurality of uniformly spaced time points. The constraint to the randomness in the frequency dimension and/or the time dimension can thus reduce the computation complexity for training model 810 used in channel prediction. As a result, in some embodiments, model training system 830 may be implemented on the local BT primary device, such as processor 407 of host chip 406 and/or processor 420 of BT chip 402 of primary device 302, as opposed to the remote device (e.g., 901 in FIG. 9). In other words, the machine learning model may be trained at the BT primary device by which the machine learning model is used.

[0074] Referring back to FIG. 6, at stage 602, in some embodiments, primary device 302 may be configured to obtain a 2D frequency hopping pattern, for example, by retrieving history information of frequency hopping performed by primary device 302 in the past. Primary device 302 may be further configured to predict the channel condition, such as the phase difference, of the first channel hi and the second channel h2, based on the obtained 2D frequency hopping pattern. For example, the estimation of a phase difference

at time to based on a 2D frequency hopping pattern using a machine learning model g

_s may be represented as:

[0075] In some embodiments, when the multiple antennas of the BT primary device are arranged according to a specific configuration, a ID time series pattern may be obtained and used, either alone or in combination with the 2D frequency hopping pattern, for predicting the channel condition, such as the phase difference. For example, FIG. 10 illustrates an AoA or an AoD of two antennas Anti and Ant2 of an exemplary BT primary device (e g., primary device 302), according to some embodiments of the present disclosure. As shown in FIG. 10, the distance between the two signal paths of Ant 1 and Ant 2 is d cos Q, such that the phase difference Φ (f, t) of the two channels becomes: (12),

where l is the wavelength, and d is the distance between the two antennas Ant 1 and Ant 2. The underlining assumption for AoA/AoD is that Q is slowly changing due to the relatively fixed position/orientation between the BT primary device and the paired BT secondary device. Since frequency / is also changing and the wavelength l is calculated by (13), where Co is the

speed of the light, the wavelength l is changing too. However, since for BT communication, the frequency range is between 2.4 GHz and 2.48 GHz, the maximum change of wavelength l is only 1/30. Thus, it can be approximated that the phase difference f in this situation is only time- dependent but frequency-independent in most of the cases. In other words, the 2D frequency hopping pattern

can be simplified as a ID time series pattern

. Different from the 2D frequency hopping pattern in both the frequency and time dimensions, the ID time series pattern is only in the time dimension, for example, having arbitrarily spaced time points.

[0076] In order to meet this condition (i.e., the underlining assumption for AoA/ AoD that

Q is slowly changing due to the relatively fixed position/orientation between the BT primary device and the paired BT secondary device), in some embodiments, the first antenna Anti and the second antenna Ant2 may be arranged on the BT primary device in a way, such that the correlation between the change of phase difference and frequency hopping of the BT primary device is below a preset threshold. In other words, the first antenna Anti and the second antenna Ant2 may have a special physical arrangement to meet the underlining assumption for AoA/ AoD as described above. [0077] Referring back to FIG. 6, alternatively or additionally, at stage 602, primary device

302 may also be configured to obtain a ID time series pattern, for example, by retrieving history information of frequency hopping of primary device 302 in the past, and predict the channel condition, such as the phase difference, of the first channel hi and the second channel h2, based on the obtained ID time series pattern, provided that the first antenna Anti and the second antenna Ant2 are arranged on primary device 302 in a way, such that the correlation between the change of phase difference and frequency hopping of primary device 302 is below a threshold. It is understood that in some examples, both the 2D frequency hopping pattern and the ID time series pattern may be obtained and used by primary device 302 to predict the channel condition.

[0078] At stage 604, primary device 302 may perform beamforming based on the predicted channel condition, such as the phase difference, to ensure the constructive interference of the two signals arriving at secondary device 304. In some embodiments, primary device 302 may be configured to transmit, by the first antenna Anti, a first signal over the first channel hi to the antenna of secondary device 304 with beamforming based on the predicted channel condition. In some embodiments, primary device 302 may be configured to transmit, by the second antenna Ant2, a second signal over the second channel h2 to the antenna of secondary device 304 with beamforming based on the predicted channel condition. At stage 606, primary device 302 and secondary device 304 may switch roles, such that primary device 302 may receive signals transmitted from the antenna of secondary device 304 to the first and second antennas Ant 1 and Ant 2 over the first and second channels hi and h2, respectively.

[0079] FIG. 11 illustrates a flow chart of an exemplary method 1100 of BT communication, according to some embodiments of the present disclosure. Examples of the apparatus that can perform operations of method 1100 include, for example, primary device 302 depicted in FIG. 3 or any other apparatus disclosed herein. It is understood that the operations shown in method 1100 are not exhaustive and that other operations can be performed as well before, after, or between any of the illustrated operations. Further, some of the operations may be performed simultaneously, such as operations 1106 and 1108, or in a different order than shown in FIG. 11.

[0080] Referring to FIG. 1102, method 1100 starts at operation 1102, in which at least one of a 2D frequency hopping pattern or a ID time series pattern of the primary device is obtained. In some embodiments, the 2D frequency hopping pattern includes a plurality of uniformly spaced time points. In some embodiments, the 2D frequency hopping pattern includes a predetermined set of frequencies. Operation 1102 may be performed by channel prediction module 812 implemented on processor 407 and/or processor 420 of primary device 302. For example, channel prediction module 812 may retrieve pattern 814, such as the 2D frequency hopping pattern and/or the ID time series pattern of primary device 302 in the past from memory 413, 412, and/or 408. [0081] Method 1100 proceeds to operation 1104, as illustrated in FIG. 11, in which a channel condition of a first channel and a second channel is predicted based, at least in part, on the at least one of the 2D frequency hopping pattern or the ID time series pattern. In some embodiments, the channel condition includes a phase difference between the first channel and the second channel. In some embodiments, the prediction uses a machine learning model trained at the primary device or at a remote device. In some embodiments, the machine learning model is received from the remote device. Operation 1104 may be performed by channel prediction module 812 implemented on processor 407 and/or processor 420 of primary device 302. For example, channel prediction module 812 may generate prediction result 816, such as the channel condition including the phase difference between the first and second channels hi and h2, based on pattern 814, such as the 2D frequency hopping pattern and/or the ID time series pattern of primary device 302, using model 810, such as a machine learning model trained by model training module 802 implemented on primary device 302 or remote device 901.

[0082] Method 1100 proceeds to operation 1106, as illustrated in FIG. 11, in which a first signal is transmitted over the first channel to an antenna of a secondary device based on the channel condition. Operation 1106 may be implemented by BT chip 402 and antennas 410 of primary device 302. For example, processor 420 of BT chip 402 may control the first antenna Anti to transmit the first signal over the first channel hi to the antenna of secondary device 304 based on the channel condition, for example, by performing beamforming.

[0083] At operation 1108, a second signal is transmitted over the second channel to the antenna of a secondary device based on the channel condition. Operation 1108 may be implemented by BT chip 402 and antennas 410 of primary device 302. For example, processor 420 of BT chip 402 may control the second antenna Ant2 to transmit the second signal over the second channel h2 to the antenna of secondary device 304 based on the channel condition, for example, by performing beamforming.

[0084] FIG. 12 illustrates another exemplary multi-antenna BT communication scheme, according to some embodiments of the present disclosure. As shown in FIG. 12, in a connection event, primary device 302 may act as the receiving device first at stage 1202 and then switch to the transmitting device at stage 1206, while secondary device 304 may act as the transmitting device first at stage 1202 and then switch to the receiving device at stage 1206. In other words, primary device 302 acts as the slave device, while secondary device 304 acts as the master device in this connection event. At stage 1202, primary device 302 may be configured to receive, by the first antenna Anti, a third signal over the first channel hi from the antenna of secondary device 304, and receive, by the second antenna Ant2, a fourth signal over the second channel h2 from the antenna of secondary device 304.

[0085] As a result, primary device 302 can determine the channel condition based on the signals received from secondary device 304 prior to stage 1206 when primary device 302 starts to transmit data to secondary device 304 since primary device 302 starts as the receiving device first in the connection event. Thus, at stage 1204, primary device 302 may perform channel prediction to predict the channel condition, such as the phase difference of the first and second channels hi and h2, based on the signals received from secondary device 304. Primary device 302 then may perform beamforming based on the predicted channel condition, such as the phase difference, to ensure the constructive interference of the two signals arriving at secondary device 304. Then, at stage 1206, primary device 302 may be configured to transmit, by the first antenna Anti, a first signal over the first channel hi to the antenna of secondary device 304 with beamforming based on the predicted channel condition. In some embodiments, primary device 302 may be configured to transmit, by the second antenna Ant2, a second signal over the second channel h2 to the antenna of secondary device 304 with beamforming based on the predicted channel condition.

[0086] FIG. 13 illustrates a flow chart of another exemplary method 1300 of BT communication, according to some embodiments of the present disclosure. Examples of the apparatus that can perform operations of method 1300 include, for example, primary device 302 depicted in FIG. 3 or any other apparatus disclosed herein. It is understood that the operations shown in method 1300 are not exhaustive and that other operations can be performed as well before, after, or between any of the illustrated operations. Further, some of the operations may be performed simultaneously, such as operations 1302 and 1304, or in a different order than shown in FIG. 13.

[0087] Referring to FIG. 13, method 1300 starts at operation 1302, in which a third signal is received from the antenna of the secondary device over the first channel. Operation 1302 may be implemented by BT chip 402 and antennas 410 of primary device 302. For example, processor 420 of BT chip 402 may control the first antenna Anti to receive the third signal over the first channel hi from the antenna of secondary device 304. At operation 1104, a fourth signal is received from the antenna of the secondary device over the second channel. Operation 1304 may be implemented by BT chip 402 and antennas 410 of primary device 302. For example, processor 420 of BT chip 402 may control the second antenna Ant2 to receive the fourth signal over the second channel h2 from the antenna of secondary device 304

[0088] Method 1300 proceeds to operation 1306, as illustrated in FIG. 13, in which the channel condition of the first channel and the second channel is predicted based, at least in part, on the received third and fourth signals. Operation 1306 may be performed by channel prediction module 812 implemented on processor 407 and/or processor 420 of primary device 302. For example, channel prediction module 812 may generate prediction result 816, such as the channel condition including the phase difference between the first and second channels hi and h2, based on signals received over the first and second channels hi and h2. It is understood that in some examples, the scheme and method disclosed in FIGs. 12 and 13 may be combined with the scheme and method disclosed in FIGs. 6-11 such that both the signals received from secondary device 304 over the channels hi and h2 and the patterns of primary device 302 can be used to predict the channel condition of the channels hi and h2.

[0089] Other than performing the channel prediction by primary device 302, in some embodiments, channel estimation may be performed by secondary device 304 and then provided to primary device 302 for beamforming. For example, FIG. 14 illustrates still another exemplary multi-antenna BT communication scheme, according to some embodiments of the present disclosure. As shown in FIG. 14, in a connection event, primary device 302 may act as the transmitting device first at stage 1402 and then switch to the receiving device at stage 1406, while secondary device 304 may act as the receiving device first at stage 1402 and then switch to the transmitting device at stage 1406. At stage 1402, primary device 302 may be configured to encode the signals to be transmitted to secondary device 304 using STBC, and then transmit the STBC- encoded signals to secondary device 304 to allow secondary device 304 to perform channel estimation based on the STBC-encoded signals at stage 1404 to estimate the channel condition, such as the phase difference of the first and second channels hi and h2. At stage 1406, secondary device 304 may be configured to provide the estimated channel condition to primary device 302 for future beamforming.

[0090] STBC is a technique used in wireless communications to transmit multiple copies of a data stream across a number of antennas and to exploit the various received versions of the data to improve the reliability of data transfer. STBC may be orthogonal, meaning that the STBC may be designed such that the vectors representing any pair of columns taken from the coding matrix are orthogonal. For example, FIG. 15 illustrates exemplary symbol structures of STBC used by a BT primary device (e g., primary device 302), according to some embodiments of the present disclosure. As shown in FIG. 15, the BT symbol is transmitted by the first antenna Anti during Gaussian frequency-shift keying (GFSK) time as well as 8 phase-shift keying (8PSK) time. During the 8PSK time, the BT symbol may include a synchronization word (Sync) at the beginning, followed by the Payload and Trailer. The BT symbol transmitted by the second antenna Ant2, however, may not be transmitted during the GFSK time, but may be transmitted during the 8PSK time with the same structure as the BT symbol transmitted by the first antenna Anti. To ensure STBC is orthogonal, the synchronization words in both BT symbols may be orthogonal.

[0091] As shown in FIG. 16, as to the payload content, the original data to be transmitted by first antenna Anti may be [s1, s2; s3, s4 ...], and the STBC-encoded data in the BT symbol transmitted by first antenna Anti may become [s1, -s2*; s3, -s4* ...], wherein * represents the conjugate of s. The original data to be transmitted by second antenna Ant2 may be [s1, s2; s3, s4 ... ], and the STBC-ended data in the BT symbol transmitted by second antenna Ant2 may become [s2, si1; s4, s3* ...]. The received STBC-encoded signal at the single antenna of secondary device 304 may be expressed as:

(14),

where .s represents the TX signal, r represents the RX signal, h represents the reciprocal air- propagation fading channel, and n represents the noise.

[0092] Thus, primary device 302 may not need to have knowledge of air-propagation channels, and the channel estimation can be done by secondary device 304 based on the received pairs of BT symbols from the first and second antennas Anti and Ant2 over the channels hi and h2. Secondary device 304 can perform channel estimation based on the orthogonal synchronization words and the STBC-encoded payloads in the pair of BT symbols. In some embodiments, primary device 302 may transmit the STBC-encoded signals in a broadcasting mode without specifically dedicating an intended secondary device 304, such that any secondary device 304 receiving the STBC-encoded signals from primary device 302 can perform channel estimation to estimate the channel condition of the corresponding channels.

[0093] FIGs. 17A and 17B illustrate flow charts of another exemplary method 1700 of BT communication, according to some embodiments of the present disclosure. Examples of the apparatus that can perform operations of method 1700 include, for example, primary device 302 and secondary device 304 depicted in FIG. 3 or any other apparatus disclosed herein. It is understood that the operations shown in method 1700 are not exhaustive and that other operations can be performed as well before, after, or between any of the illustrated operations. Further, some of the operations may be performed simultaneously, such as operations 1704 and 1708, or in a different order than shown in FIGs. 17A and 17B.

[0094] Referring to FIG. 1702, method 1700 starts at operation 1702A, in which a first signal and a second signal are encoded using STBC. Operation 1702 may be implemented on processor 420 of primary device 302. For example, BT chip 402 of primary device 302 may encode two signals to be transmitted by first and second antennas Anti and Ant2 over channels hi and h2, respectively, using STBC disclosed in FIGs. 15 and 16.

[0095] Method 1700 proceeds to operation 1704, as illustrated in FIG. 17A, in which the encoded first signal is transmitted over the first channel to an antenna of a secondary device. Operation 1704 may be implemented by BT chip 402 and antennas 410 of primary device 302. For example, processor 420 of BT chip 402 may control the first antenna Anti to transmit the STBC-encoded first signal over the first channel hi to the antenna of secondary device 304. [0096] At operation 1706, the encoded second signal is transmitted over the second channel to the antenna of the secondary device. Operation 1706 may be implemented by BT chip 402 and antennas 410 of primary device 302. For example, processor 420 of BT chip 402 may control the second antenna Ant2 to transmit the STBC-encoded second signal over the second channel hi to the antenna of secondary device 304.

[0097] Method 1700 proceeds to operation 1708, as illustrated in FIG. 17B, in which the encoded first signal and the encoded second signal are received over the first channel and the second channel from the first antenna and the second antenna of the primary device, respectively. Operation 1708 may be implemented by BT chip 502 and antenna 510 of secondary device 304. For example, processor 520 of BT chip 502 may control the antenna to receive the STBC-encoded first and second signals over the first channel and second channels hi and h2 from the first and second antennas Anti and Ant2 of primary device 302, respectively.

[0098] Method 1700 proceeds to operation 1710, as illustrated in FIG. 17B, in which a channel condition of the first channel and the second channel is estimated based, at least in part, on the encoded first signal and the encoded second signal. Operation 1710 may be implemented by BT chip 502 of secondary device 304. For example, processor 520 of BT chip 502 may estimate the channel condition of channels hi and hlb based on the received STBC-encoded first and second signals.

[0099] Method 1700 proceeds to operation 1712, as illustrated in FIG. 17B, in which the channel condition is provided to the primary device. Operation 1712 may be implemented by BT chip 502 and antenna 510 of secondary device 304. For example, processor 520 of BT chip 502 may control the antenna to transmit the channel condition to primary device 302.

[0100] In some embodiments, the scheme and method disclosed in FIGs. 14-17 may be used for high data throughput (HDT) applications, such as high-fidelity music streaming, as 8PSK needs much higher SNR for reliable data exchange. In some embodiments, each antenna may alternatively transmit the full package during both the GFSK and 8PSK times or the partial package during only the 8PSK time.

[0101] In various aspects of the present disclosure, the functions described herein may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or encoded as instructions or code on a non-transitory computer-readable medium. Computer-readable media includes computer storage media. Storage media may be any available media that can be accessed by a BT primary device or a BT secondary device, such as node 200 in FIG. 2. By way of example, and not limitation, such computer-readable media can include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, HDD, such as magnetic disk storage or other magnetic storage devices, Flash drive, SSD, 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, such as a mobile device or a computer. Disk and disc, as used herein, includes CD, laser disc, optical disc, DVD, and floppy disk where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

[0102] According to one aspect of the present disclosure, a primary device of BT communication includes a first antenna, a second antenna, a processor operatively coupled to the first and second antennas, and memory storing instructions. The first antenna is configured to communicate with an antenna of a secondary device of Bluetooth communication over a first channel. The second antenna is configured to communicate with the antenna of the secondary device over a second channel. Execution of the instructions causes the processor to obtain at least one of a 2D frequency hopping pattern or a ID time series pattern of the primary device. Execution of the instructions also causes the processor to predict a channel condition of the first channel and the second channel based, at least in part, on the at least one of the 2D frequency hopping pattern or the ID time series pattern. Execution of the instructions further causes the processor to control the first antenna and the second antenna to transmit a first signal and a second signal over the first channel and the second channel, respectively, to the antenna of the secondary device based on the channel condition.

[0103] In some embodiments, the channel condition includes a phase difference between the first channel and the second channel.

[0104] In some embodiments, the 2D frequency hopping pattern includes a plurality of uniformly spaced time points or a plurality of uniformly spaced time points.

[0105] In some embodiments, the 2D frequency hopping pattern includes a predetermined set of frequencies.

[0106] In some embodiments, to predict the channel condition, execution of the instructions causes the processor to predict the phase difference based on the 2D frequency hopping pattern using a machine learning model.

[0107] In some embodiments, the machine learning model is trained at a remote device, and execution of the instructions causes the processor to receive the machine learning model from the remote device.

[0108] In some embodiments, the machine learning model is trained at the primary device.

[0109] In some embodiments, the first antenna and the second antenna are arranged on the primary device in a way such that a correlation between a change of phase difference and frequency hopping of the primary device is below a threshold. In some embodiments, to predict the channel condition, execution of the instructions causes the processor to predict the phase difference based on the ID time series pattern.

[0110] In some embodiments, the first antenna is further configured to receive a third signal from the antenna of the secondary device over the first channel, the second antenna is further configured to receive a fourth signal from the antenna of the secondary device over the second channel, and the channel condition is predicted based, at least in part, on the received third and fourth signals.

[0111] According to another aspect of the present disclosure, a method of BT communication implemented on a primary device is disclosed. At least one of a 2D frequency hopping pattern or a ID time series pattern of the primary device are obtained by a processor. A channel condition of a first channel and a second channel is predicted based, at least in part, on the at least one of the 2D frequency hopping pattern or the ID time series pattern by the processor. A first signal is transmitted over the first channel to an antenna of a secondary device of Bluetooth communication based on the channel condition by a first antenna. A second signal is transmitted over the second channel to the antenna of the secondary device based on the channel condition by a second antenna.

[0112] In some embodiments, the channel condition includes a phase difference between the first channel and the second channel.

[0113] In some embodiments, the 2D frequency hopping pattern includes a plurality of uniformly spaced time points or a plurality of uniformly spaced time points.

[0114] In some embodiments, the 2D frequency hopping pattern includes a predetermined set of frequencies.

[0115] In some embodiments, to predict the channel condition, the phase difference is predicted based on the 2D frequency hopping pattern using a machine learning model.

[0116] In some embodiments, the machine learning model is received from the remote device, and the machine learning model is trained at a remote device.

[0117] In some embodiments, the machine learning model is trained at the primary device.

[0118] In some embodiments, the first antenna and the second antenna are arranged on the primary device in a way such that a correlation between a change of phase difference and frequency hopping of the primary device is below a threshold. In some embodiments, to predict the channel condition, the phase difference is predicted based on the ID time series pattern.

[0119] In some embodiments, a third signal is received from the antenna of the secondary device over the first channel by the first antenna, a fourth signal is received from the antenna of the secondary device over the second channel by the second antenna, and to predict the channel condition, the channel condition is predicted based, at least in part, on the received third and fourth signals.

[0120] According to still another aspect of the present disclosure, a system of BT communication includes a primary device and a secondary device. The primary device includes a first antenna, a second antenna, a processor operatively coupled to the first and second antennas, and memory storing instructions. The first antenna is configured to communicate with an antenna of the secondary device over a first channel. The second antenna is configured to communicate with the antenna of the secondary device over a second channel. Execution of the instructions causes the processor to encode a first signal and a second signal using STBC, and control the first antenna and the second antenna to transmit the encoded first signal and the encoded second signal over the first channel and the second channel, respectively. The secondary device includes the antenna, a processor operatively coupled to the antenna, and memory storing instructions. The antenna is configured to receive the encoded first signal and the encoded second signal over the first channel and the second channel from the first antenna and the second antenna of the primary device, respectively. Execution of the instructions causes the processor to estimate a channel condition of the first channel and the second channel based, at least in part, on the encoded first signal and the encoded second signal, and provide the channel condition to the primary device. [0121] In some embodiments, the encoded first signal and the encoded second signal includes orthogonal synchronization words.

[0122] 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.

[0123] 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.

[0124] The Summary and Abstract sections may set forth one or more but not all exemplary 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.

[0125] 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.

[0126] 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 claims and their equivalents.

Claims

WHAT IS CLAIMED IS:

1. A primary device of Bluetooth communication, comprising: a first antenna configured to communicate with an antenna of a secondary device of Bluetooth communication over a first channel; a second antenna configured to communicate with the antenna of the secondary device over a second channel; a processor operatively coupled to the first and second antennas; and memory storing instructions that, when executed by the processor, cause the processor to: obtain at least one of a two-dimensional (2D) frequency hopping pattern or a one dimensional (ID) time series pattern of the primary device; predict a channel condition of the first channel and the second channel based, at least in part, on the at least one of the 2D frequency hopping pattern or the ID time series pattern; and control the first antenna and the second antenna to transmit a first signal and a second signal over the first channel and the second channel, respectively, to the antenna of the secondary device based on the channel condition.

2. The primary device of claim 1, wherein the channel condition comprises a phase difference between the first channel and the second channel.

3. The primary device of claim 1, wherein the 2D frequency hopping pattern comprises a plurality of uniformly spaced time points or a plurality of non-uniformly spaced time points.

4. The primary device of claim 1, wherein the 2D frequency hopping pattern comprises a predetermined set of frequencies.

5. The primary device of claim 2, wherein to predict the channel condition, execution of the instructions causes the processor to predict the phase difference based on the 2D frequency hopping pattern using a machine learning model.

6. The primary device of claim 5, wherein the machine learning model is trained at a remote device; and execution of the instructions causes the processor to receive the machine learning model from the remote device.

7. The primary device of claim 5, wherein the machine learning model is trained at the primary device.

8. The primary device of claim 2, wherein the first antenna and the second antenna are arranged on the primary device in a way such that a correlation between a change of phase difference and frequency hopping of the primary device is below a threshold; and to predict the channel condition, execution of the instructions causes the processor to predict the phase difference based on the ID time series pattern.

9. The primary device of claim 1, wherein the first antenna is further configured to receive a third signal from the antenna of the secondary device over the first channel; the second antenna is further configured to receive a fourth signal from the antenna of the secondary device over the second channel; and the channel condition is predicted based, at least in part, on the received third and fourth signals.

10. A method of Bluetooth communication implemented on a primary device, comprising: obtaining, by a processor, at least one of a two-dimensional (2D) frequency hopping pattern or a one-dimensional (ID) time series pattern of the primary device; predicting, by the processor, a channel condition of a first channel and a second channel based, at least in part, on the at least one of the 2D frequency hopping pattern or the ID time series pattern; transmitting, by a first antenna, a first signal over the first channel to an antenna of a secondary device of Bluetooth communication based on the channel condition; and transmitting, by a second antenna, a second signal over the second channel to the antenna of the secondary device based on the channel condition.

11. The method of claim 10, wherein the channel condition comprises a phase difference between the first channel and the second channel.

12. The method of claim 10, wherein the 2D frequency hopping pattern comprises a plurality of uniformly spaced time points or a plurality of non-uniformly spaced time points.

13. The method of claim 10, wherein the 2D frequency hopping pattern comprises a predetermined set of frequencies.

14. The method of claim 11, wherein predicting the channel condition comprises predicting the phase difference based on the 2D frequency hopping pattern using a machine learning model.

15. The method of claim 14, further comprising: receiving the machine learning model from a remote device, wherein the machine learning model is trained at the remote device.

16. The method of claim 14, wherein the machine learning model is trained at the primary device.

17. The method of claim 11, wherein the first antenna and the second antenna are arranged on the primary device in a way such that a correlation between a change of phase difference and frequency hopping of the primary device is below a threshold; and predicting the channel condition comprises predicting the phase difference based on the ID time series pattern.

18. The method of claim 10, further comprising: receiving, by the first antenna, a third signal from the antenna of the secondary device over the first channel; and receiving, by the second antenna, a fourth signal from the antenna of the secondary device over the second channel, wherein predicting the channel condition comprises predicting the channel condition based, at least in part, on the received third and fourth signals.

19. A system of Bluetooth communication, comprising: a primary device, and a secondary device, wherein the primary device comprises: a first antenna configured to communicate with an antenna of the secondary device over a first channel; a second antenna configured to communicate with the antenna of the secondary device over a second channel; a processor operatively coupled to the first and second antennas; and memory storing instructions that, when executed by the processor, cause the processor to: encode a first signal and a second signal using space-time block coding (STBC); and control the first antenna and the second antenna to transmit the encoded first signal and the encoded second signal over the first channel and the second channel, respectively; and the secondary device comprises: the antenna configured to receive the encoded first signal and the encoded second signal over the first channel and the second channel from the first antenna and the second antenna of the primary device, respectively; a processor operatively coupled to the antenna; and memory storing instructions that, when executed by the processor, cause the processor to: estimate a channel condition of the first channel and the second channel based, at least in part, on the encoded first signal and the encoded second signal; and provide the channel condition to the primary device.

20. The system of claim 19, wherein the encoded first signal and the encoded second signal comprise orthogonal synchronization words.