Enhancement of user activity detection

Abstract

Example embodiments of the present disclosure relate to user activity detection (UAD). A terminal device in a radio access network receives, from a network device in the radio access network, a configuration to allocate common time-frequency resources for a set of terminal devices in the radio access network and a configuration to associate the set of terminal devices with a set of conjugate symmetric sequences. The encoded transmission of the conjugate symmetric sequence indicates activity information for a group of active terminal devices in the group of terminal devices. And the terminal equipment transmits the coded conjugate symmetric sequence to the network equipment in the public time-frequency resource. By utilizing a conjugate symmetric sequence with partial phase compensation, synchronous UAD may be supported with large scale capacity and scalability for large scale access.

Description

Technical Field

[0001] Various example embodiments of the present disclosure generally relate to the field of telecommunications, and in particular, to methods, devices, apparatuses, and computer-readable storage media for user activity detection (UAD). Background Art

[0002] Machine type communication (MTC) in 5G new radio is split into ultra-reliable low-latency communication (URLLC) or critical MTC (cMTC) (in controlled environments with small payloads and low data rates), and massive MTC (mMTC) for large-scale or dense deployments with sporadic traffic patterns. In the next decade, due to the emergence of industrial use cases and the verticalization of service provisioning, these two areas will evolve into several dedicated subclasses, thus requiring multi-dimensional optimization and scalable designs.

[0003] In view of the above, 6G needs to serve a highly diverse range of applications, which cover from holographic images with extremely high data rate requirements and interconnected 360-degree XR (e.g., augmented reality / virtual reality / mixed reality) to large-scale access of various types of IoT devices. One proposed MTC service category for 6G is classified as scalable cMTC, which means supporting large-scale connections with high reliability and low latency, such as critical medical monitoring and factory automation. Scale and flexibility are also important metrics for 6G performance. It is expected that 6G supports a high connection density, such as 10 million devices per square kilometer. Summary of the Invention

[0004] Generally, example embodiments of the present disclosure provide a UAD enhancement solution.

[0005] In a first aspect of the present disclosure, a terminal device in a radio access network is provided. The terminal device includes at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the terminal device to at least: receive from a network device in the radio access network a configuration for allocating common time-frequency resources to a group of terminal devices in the radio access network and a configuration for associating the group of terminal devices with a group of conjugate symmetric sequences, wherein the encoded transmission of the conjugate symmetric sequence indicates activity information of a group of active terminal devices in the group of terminal devices; and transmit an encoded conjugate symmetric sequence to the network device on the common time-frequency resources.

[0006] In a second aspect of the present disclosure, a network device in a radio access network is provided. The network device includes: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the network device to at least: transmit to a group of terminal devices in the radio access network a configuration for allocating common time-frequency resources to the group of terminal devices and a configuration for associating the group of terminal devices with a group of conjugate symmetric sequences, wherein the encoded transmission of the conjugate symmetric sequences indicates activity information of a group of active terminal devices among the group of terminal devices; receive in the common time-frequency resources from the group of active terminal devices a superimposed conjugate symmetric sequence associated with the encoded conjugate symmetric sequences, wherein the superimposed conjugate symmetric sequence includes activity indication symbols associated with the group of terminal devices; and identify a group of active terminal devices among the group of terminal devices by solving for the activity indication symbols from the superimposed conjugate symmetric sequence.

[0007] In a third aspect of the present disclosure, a method is provided. The method includes: at a terminal device in a radio access network, receiving from a network device in the radio access network a configuration for allocating common time-frequency resources to a group of terminal devices in the radio access network and a configuration for associating the group of terminal devices with a group of conjugate symmetric sequences, wherein the encoded transmission of the conjugate symmetric sequences indicates activity information of a group of active terminal devices among the group of terminal devices; and transmitting an encoded conjugate symmetric sequence to the network device in the common time-frequency resources.

[0008] In a fourth aspect of the present disclosure, a method is provided. The method includes: at a network device in a radio access network, transmitting to a group of terminal devices in the radio access network a configuration for allocating common time-frequency resources to the group of terminal devices and a configuration for associating the group of terminal devices with a group of conjugate symmetric sequences, wherein the encoded transmission of the conjugate symmetric sequences indicates activity information of a group of active terminal devices among the group of terminal devices; receiving in the common time-frequency resources from the group of active terminal devices a superimposed conjugate symmetric sequence associated with the encoded conjugate symmetric sequences, wherein the superimposed conjugate symmetric sequence includes activity indication symbols associated with the group of terminal devices; and identifying a group of active terminal devices among the group of terminal devices by solving for the activity indication symbols from the superimposed conjugate symmetric sequence.

[0009] In a fifth aspect of the present disclosure, a first apparatus is provided. The first apparatus includes: components for receiving, at a first apparatus in a radio access network, a configuration for allocating common time-frequency resources to a group of terminal devices in the radio access network and a configuration for associating the group of terminal devices with a group of conjugate symmetric sequences, wherein the encoded transmission of the conjugate symmetric sequences indicates activity information of a group of active terminal devices in the group of terminal devices; and components for transmitting an encoded conjugate symmetric sequence to a network device in the common time-frequency resources.

[0010] In a sixth aspect of the present disclosure, a second apparatus is provided. The second apparatus includes: components for transmitting, at a second apparatus in a radio access network, a configuration for allocating common time-frequency resources to a group of terminal devices and a configuration for associating the group of terminal devices with a group of conjugate symmetric sequences to the group of terminal devices in the radio access network, wherein the encoded transmission of the conjugate symmetric sequences indicates activity information of a group of active terminal devices in the group of terminal devices; components for receiving, in the common time-frequency resources, a superimposed conjugate symmetric sequence associated with the encoded conjugate symmetric sequence from the group of active terminal devices, wherein the superimposed conjugate symmetric sequence includes activity indication symbols associated with the group of terminal devices; and components for identifying a group of active terminal devices in the group of terminal devices by solving for the activity indication symbols from the superimposed conjugate symmetric sequence.

[0011] In a seventh aspect of the present disclosure, a computer-readable medium is provided. The computer-readable medium includes program instructions for causing an apparatus to at least perform the following: at a terminal device in a radio access network, receiving from a network device in the radio access network a configuration for allocating common time-frequency resources to a group of terminal devices in the radio access network and a configuration for associating the group of terminal devices with a group of conjugate symmetric sequences, wherein the encoded transmission of the conjugate symmetric sequences indicates activity information of a group of active terminal devices in the group of terminal devices; and transmitting an encoded conjugate symmetric sequence to the network device in the common time-frequency resources.

[0012] In an eighth aspect of the present disclosure, a computer-readable medium is provided. The computer-readable medium includes program instructions for causing a device to at least perform the following: at a network device in a radio access network, transmit to a group of terminal devices in the radio access network a configuration for allocating common time-frequency resources to the group of terminal devices and a configuration for associating the group of terminal devices with a group of conjugate symmetric sequences, wherein an encoded transmission of the conjugate symmetric sequences indicates activity information of a group of active terminal devices among the group of terminal devices; receive, in the common time-frequency resources, from the group of active terminal devices a superimposed conjugate symmetric sequence associated with the encoded conjugate symmetric sequences, wherein the superimposed conjugate symmetric sequence includes activity indication symbols associated with the group of terminal devices; and identify the group of active terminal devices among the group of terminal devices by solving for the activity indication symbols from the superimposed conjugate symmetric sequence.

[0013] It should be understood that the summary section is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become readily apparent through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Some example embodiments will now be described with reference to the accompanying drawings, in which:

[0015] Figure 1 An example communication environment in which example embodiments of the present disclosure may be implemented is shown;

[0016] Figure 2 A signaling diagram for a synchronous UAD process according to some example embodiments of the present disclosure is shown;

[0017] Figure 3 A schematic diagram of resource mapping for conjugate symmetric sequences with partial phase compensation according to some example embodiments of the present disclosure is shown;

[0018] Figure 4 Example simulation results of performance comparison regarding UAD according to some example embodiments of the present disclosure are shown;

[0019] Figure 5 A flowchart of a method implemented at a terminal device according to some example embodiments of the present disclosure is shown;

[0020] Figure 6 A flowchart of a method implemented at a network device according to some example embodiments of the present disclosure is shown;

[0021] Figure 7 A simplified block diagram of a device suitable for implementing example embodiments of the present disclosure is shown; and

[0022] Figure 8A block diagram of an example computer-readable medium in accordance with some example embodiments of the present disclosure is shown.

[0023] Throughout the drawings, the same or similar reference numerals denote the same or similar elements. Detailed Description

[0024] The principles of the present disclosure will now be described with reference to some example embodiments. It should be understood that these embodiments are described for illustrative purposes only and help those skilled in the art to understand and implement the present disclosure, without implying any limitation on the scope of the present disclosure. The disclosure described herein can be implemented in various ways other than those described below.

[0025] In the following specification and claims, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0026] References in this disclosure to "one embodiment", "an embodiment", "example embodiment", etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but not every embodiment necessarily includes the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an example embodiment, it is considered within the knowledge of one of ordinary skill in the art to affect such feature, structure, or characteristic in connection with other embodiments, whether or not explicitly described.

[0027] It should be understood that although the terms "first" and "second" etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish the functions of the various elements. As used herein, the term "and / or" includes any and all combinations of one or more of the listed terms.

[0028] The terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the example embodiments. As used herein, the singular forms "a", "an", and "the" are also intended to include the plural forms unless the context clearly indicates otherwise. It should be further understood that the terms "comprises", "comprising", "has", "having", "contains", "containing", and / or "including" when used herein specify the presence of the stated features, elements, and / or components, etc., but do not preclude the presence or addition of one or more other features, elements, components, and / or combinations thereof.

[0029] As used herein, "at least one of the following: <list of two or more elements>" and "at least one of <list of two or more elements>" and like phrases, where the list of two or more elements is joined by "and" or "or", means at least any one of the elements, or at least any two or more of the elements, or at least all of the elements.

[0030] As used in this application, the term "circuitry" can refer to one or more or all of the following: (a) Only hardware circuit implementations (such as implementations only in analog / or digital circuitry) and (b) combinations of hardware circuits and software, for example (if applicable): (i) Combinations of (multiple) analog and / or digital hardware circuits with software / firmware and (ii) Any part of (multiple) hardware processors with software (including (multiple) digital signal processors, software, (multiple) memories that work together to enable a device such as a mobile phone or a server to perform various functions) and (c) (Multiple) hardware circuits and / or (multiple) processors, such as (multiple) microprocessors or a part of (multiple) microprocessors that require software (e.g., firmware) for operation (but the software may be absent when not required for operation).

[0031] This definition of circuitry applies to the term as used in all of this application (including any claims). As another example, as used in this application, the term circuitry also encompasses implementations of only hardware circuits or processors (or multiple processors) or a part of a hardware circuit or processor and their (or their) accompanying software and / or firmware. The term circuitry also encompasses, for example and as applicable to a particular claim element, a baseband integrated circuit or a processor integrated circuit for a mobile device or a similar integrated circuit in a server, a cellular network device, or other computing or network devices.

[0032] As used herein, the term "communication network" refers to a network that follows any suitable communication standard, such as a fifth-generation (5G) system, Long-Term Evolution (LTE), Advanced LTE (LTE-A), Wideband Code Division Multiple Access (WCDMA), High-Speed Packet Access (HSPA), Narrowband Internet of Things (NB-IoT), etc. Additionally, the communication between the terminal device and the network device in the communication network can be performed according to any suitable generation of communication protocol, including but not limited to the first-generation (1G), second-generation (2G), 2.5G, 2.75G, third-generation (3G), fourth-generation (4G), 4.5G, fifth-generation (5G) New Radio (NR) communication protocol and / or any other protocol known currently or developed in the future. Embodiments of the present disclosure can be applied to various communication systems. Given the rapid development of communication, there will of course also be future types of communication technologies and systems that can embody the present disclosure. It should not be regarded as limiting the scope of the present disclosure to the aforementioned systems.

[0033] As used herein, the term "network device" refers to a node in a communication network through which a terminal device accesses the network and receives services from the network. Depending on the terminology and technology applied, the network device can refer to a base station (BS) or an access point (AP), for example, Node B (NodeB or NB), evolved Node B (eNode B or eNB), next-generation Node B (NRNB), Remote Radio Unit (RRU), Radio Head (RH), Remote Radio Head (RRH), Integrated Access and Backhaul (IAB) node, relay, low-power node (such as femto, pico, etc.). It is allowed to define the network device as part of the gNB, for example, in the CU / DU split, in which case the network device is defined as the gNB-CU or gNB-DU.

[0034] As used herein, the term "terminal device" refers to any end device capable of wireless communication. By way of example and not limitation, a terminal device may also be referred to as a communication device, a user equipment (UE), a subscriber station (SS), a portable subscriber station, a mobile station (MS), or an access terminal (AT). Terminal devices may include, but are not limited to, mobile phones, cellular phones, smart phones, IP voice (VoIP) phones, wireless local loop phones, tablet computers, wearable terminal devices, personal digital assistants (PDAs), portable computers, desktop computers, image capture terminal devices such as digital cameras, game terminal devices, music storage and playback appliances, in-vehicle wireless terminal devices, wireless endpoints, mobile stations, laptop embedded equipment (LEE), laptop mounted equipment (LME), USB dongles, smart devices, wireless customer premise equipment (CPE), Internet of Things (IoT) devices, watches or other wearable devices, head-mounted displays (HMDs), vehicles, drones, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in the context of an industrial and / or automated processing chain), consumer electronic devices, devices operating on commercial and / or industrial wireless networks, etc. A terminal device may also correspond to the mobile terminal (MT) part of an integrated access and backhaul (IAB) node (also referred to as a relay node). In the following description, the terms "terminal device", "communication device", "terminal", "user equipment", and "UE" may be used interchangeably. In the following description, the terms "sequence", "preamble", "pilot signal", and "signal" may be used interchangeably.

[0035] As used herein, the term "active terminal device" or "active UE" refers to a terminal device that becomes active at one or more time slots and initiates a service request flag, e.g., a scheduling request for data waiting to be transmitted, a location request, a connection status establishment request, or a retransmission request related to a negative acknowledgment (NAK) in the ARQ (automatic repeat request) protocol. Additionally, the term "inactive terminal device" or "inactive UE" refers to a terminal device that does not perform the operations performed by an "active terminal device" or "active UE" and remains silent at one or more time slots.

[0036] Although the functions described herein can be performed in fixed and / or wireless network nodes in various example embodiments, in other example embodiments, the functions can be implemented in user equipment devices such as cellular phones or tablet computers or laptop computers or desktop computers or mobile IoT devices or fixed IoT devices. The user equipment can, for example, be suitably equipped with the corresponding capabilities as described in connection with fixed and / or wireless network nodes. The user equipment device can be a user equipment and / or a control device configured to control the user equipment when installed in the user equipment, such as a chipset or a processor. Examples of such functions include a bootstrapping server function and / or a home subscriber server, which can be implemented in the user equipment device by providing software to the user equipment device that is configured to cause the user equipment device to perform from the perspective of these functions / nodes.

[0037] In contrast to human - centric communication, machine - centric communication (e.g., scalable cMTC) generally has two distinctive features: · The whole system needs to support massive connectivity - the number of devices connected to a cellular BS can be on the order of 10 4 to 10 7 . The macro BS preferably provides unified massive access for various types of IoT devices, thus providing a low - cost solution for supporting massive connectivity with high reliability and low latency. Commercially, telecommunication providers prefer unified solutions. ● The traffic pattern is sporadic - at any given time, only a small fraction of the potential devices are active. Generally, machine - type devices connect to the network asynchronously and sporadically to send small data payloads. The sporadicity is due to the inherent burstiness of event - driven IoT communication in a controlled and / or sensed environment. Most devices make random requests independently and there is less periodicity that can be tracked and exploited. Therefore, it is impossible for the network to predict in advance when and which device will transmit a data packet.

[0038] In 6G MTC, massive devices initiate sporadic but unpredictable scheduling requests to request uplink resources from the uplink scheduler. A scheduling request is a flag indicating that a device needs uplink resources for uplink shared channel (UL - SCH) transmission. In LTE and NR, there are two ways to issue the flag: · For a device that has been configured with dedicated request resources, the scheduling request is typically transmitted on the physical uplink control channel (PUCCH) using pre-configured and periodically recurring PUCCH resources dedicated to that device. Each device can be assigned dedicated PUCCH scheduling request resources, and the periodicity of the dedicated PUCCH scheduling request resources ranges from every second OFDM symbol for supporting latency-critical services to every 80 ms at most for low overhead. However, as the connection density increases to 10 million devices per square kilometer, this resource configuration becomes unsustainable, resulting in unacceptable waste on the spectrum. For a large number of devices with low traffic intensity, it is not wise to maintain dedicated PUCCHs simultaneously. ● For a device that has not been configured with scheduling request resources, it relies on the random access mechanism to request resources. This can be used to create a contention-based mechanism for requesting resources. However, as an example of classic ALOHA, the physical layer random access channel (PRACH) mechanism imposes a limit on the number of active devices authorized to access the network.

[0039] For these reasons, both of these methods may not be feasible for scalable cMTC. Instead of these two methods, UAD is a more efficient and effective way to handle uncertain and random scheduling requests. In fact, there is a small subset of active devices for scheduling requests at a given transmission moment or transmission frame. Before establishing a successful connection between the device and the BS, UAD helps the BS identify the active subset among all the devices. At the beginning of a transmission cycle, once the BS knows which device(s) has an actual need to transmit data, the BS can allocate scheduling grants to this small number of active users, enabling the active users to further provide more detailed scheduling information to the BS. The qualified UAD expected for large-scale access is accurate, fast, and can scale with minimal measurement resource cost.

[0040] Although the subset of active users is random and unknown, on the other hand, this subset of active users may have established a connection state class through the initial access process. In addition to the dedicated UL control channel for scheduling requests, the user may have received necessary configurations, such as system information, registered user ID, synchronized uplink timing, etc., and acquired partial knowledge of the corresponding UL channel, which allows for synchronized UAD with high accuracy.

[0041] According to some example embodiments of the present disclosure, a solution for UAD and a sequence design for synchronizing UAD are provided. In this solution, terminal devices (e.g., UEs) in a radio access network are respectively pre-assigned conjugate symmetric sequences, and these symmetric sequences can be distinguished by using associated frequency parameters. The active terminal devices respectively transmit the associated conjugate symmetric sequences encoded with partial phase compensation on common resources. The network device (e.g., gNB) can identify the active terminal devices among the terminal devices by solving the activity indication symbols from the superimposed conjugate symmetric sequences in the common resources.

[0042] In this way, synchronous UAD is supported in the radio access network, which realizes fast and efficient active user identification. Synchronous UAD can be easily integrated with the scheduling request grant procedure for large-scale access, thus facilitating a low-cost and high-performance scheduling request grant procedure. Moreover, synchronous UAD can be easily integrated with the ARQ protocol, thus avoiding dedicated feedback channels for ACK / NAK and reducing signaling overhead.

[0043] Example embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. Example environment

[0044] Figure 1 An example communication environment 100 in which example embodiments of the present disclosure can be implemented is shown. The communication environment 100 may be a radio access network. As Figure 1 shown, the communication environment 100 includes a group of terminal devices 110-1 to 110-N and a network device 120, where N represents the number of terminal devices 110-1 to 110-N, and the terminal devices 110-1 to 110-N may be collectively referred to as terminal devices 110 hereinafter.

[0045] The group of terminal devices 110-1 to 110-N may be potential user devices (e.g., UEs) having traffic to be transmitted (e.g., NAK messages in the ARQ protocol) in a cell provided by the network device 120 (e.g., gNB). The terminal device 110 and the network device 120 can communicate with each other. In the context of the present disclosure, the link from the terminal device 110 to the network device 120 is referred to as the uplink (UL), and the link from the network device 120 to the terminal device 110 is referred to as the downlink (DL). In the UL, the terminal device 110 is a transmitting (Tx) device or transmitter, and the network device 120 is a receiving (Rx) device or receiver. In the DL, the network device 120 is a Tx device or transmitter, and the terminal device 110 is an Rx device or receiver.

[0046] As an example of an implementation, each of the network device 120 and the terminal devices 110-1 to 110-N can have a single or multiple transmission antennas. A group of terminal devices 110-1 to 110-N can be respectively labeled as n∈S = {1, …, N}. Assume that the N terminal devices 110 have implemented an initial access process through a previous random access process, which establishes a connection state class other than the dedicated UL control channel for scheduling requests. Accordingly, the terminal devices 110 may have received necessary configurations, such as system information, registered user IDs, synchronized uplink timing, etc., and have acquired prior knowledge of the corresponding UL channels. Assume that the timing alignment information is valid during the UAD process, and for static and low-mobility UEs, this timing alignment information does not expire. In this way, the terminal device 110 can appropriately adjust the timing advance of the terminal device 110 respectively for UL transmission, and enable synchronized UL transmission regarding the reception window at the network device 120.

[0047] Each of the terminal devices 110-1 to 110-N is pre-assigned a unique preamble for all time slots. This preamble can serve as an ID for the corresponding user, and thus this preamble can be used for UAD. Specifically, at each time slot, the network device 120 can detect at least one active terminal device by detecting which (which) preambles are present. In other words, such a preamble is proprietary to each terminal device 110. Generally, at a given time slot, only a small fraction of the potential devices (denoted as the active subset ) become active and initiate a scheduling request for UL data waiting to be transmitted. The active subset S A refers to a group of active terminal devices, and this group of active terminal devices is random and unknown to the network device 120. As an example, in Figure 1 the example shown, the active subset S A includes the terminal device 110-1, the terminal device 110-n, and the terminal device 110-N, while the terminal devices 110-2 and 110-3 are inactive terminal devices.

[0048] In some example embodiments, the preamble can be in the form of a conjugate symmetric sequence, which is a complex conjugate symmetric sine sequence with a variable frequency parameter. The conjugate symmetric sequences associated with a group of terminal devices 110-1 to 110-N can be non-orthogonal complex conjugate symmetric sine sequences, and different terminal devices can be distinguished by unique frequency parameters to avoid preamble conflicts. Such a sequence design can facilitate convex signal processing to overcome multi-user interference, thereby achieving efficient and accurate UAD.

[0049] In the case where the terminal device 110-n becomes an active terminal device, that is The terminal device 110-n will transmit the coded conjugate symmetric sequence with partial phase compensation to the network device 120. In other words, the coded transmission of the conjugate symmetric sequence indicates the activity information of the active terminal devices in the entire group of terminal devices.

[0050] To implement UAD, the network device 120 may configure common time-frequency resources (e.g., physical resource blocks (PRBs)) for all N terminal devices 110 for the transmission of the corresponding sequence or a variant of the corresponding sequence. The shared PRBs may include multiple resource elements (REs) in a coherent block, and each RE carries one symbol of the conjugate symmetric sequence. The number of REs may be determined based on the expected number of active devices obtained from the total number of terminal devices 110 and the probabilistic characteristics of the traffic. For the case of multi-antenna deployment, the common time-frequency resources may be based on a common antenna port. Without loss of generality, the channel coefficient from the terminal device 110-n to the network device 120 in the common time-frequency resources is denoted as

[0051] In this way, the network device 120 can receive synchronous and superimposed signals from a group of active terminal devices. The network device 120 can identify the unknown active subset S based on the superimposed conjugate symmetric sequence A , which will be discussed in detail below. Therefore, synchronous UAD is supported in the case of high accuracy and low cost.

[0052] In the case where UAD is integrated with the scheduling request grant procedure for massive access, the network device 120 can also notify the identified active terminal devices through a mapping list. Each row in the list (which is dedicated to the identified terminal device) includes the ID of the corresponding terminal device and the associated scheduling grant. The network device 120 can allocate these resources only to the identified terminal devices. However, any terminal device can check the list. By checking, the active terminal device can determine whether it has been successfully identified by the network device 120.

[0053] It should be understood that Figure 1 the number of terminal devices, network devices, and their connections shown in

[0054] Communications in the communication environment 100 can be implemented according to any suitable one or more communication protocols, including but not limited to cellular communication protocols such as the first generation (1G), second generation (2G), third generation (3G), fourth generation (4G), fifth generation (5G), and sixth generation (6G), wireless local area network communication protocols such as those of the Institute of Electrical and Electronics Engineers (IEEE) 802.11, and / or any other protocol known currently or developed in the future. Additionally, the communications can utilize any suitable wireless communication technology, including but not limited to: Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Frequency Division Duplexing (FDD), Time Division Duplexing (TDD), Multiple-Input Multiple-Output (MIMO), Orthogonal Frequency Division Multiplexing (OFDM), Discrete Fourier Transform Spread OFDM (DFT-s-OFDM), and / or any other technology known currently or developed in the future. Operating principle for communication and example signaling

[0055] Now refer to Figure 2 , which shows a signaling diagram 200 for synchronizing the UAD according to some example embodiments of the present disclosure. The synchronizing UAD process 200 can involve the set of terminal devices 110-1 to 110-N and the network device 120. In particular, some actions involve the active terminal device 110-1, the active terminal device 110-n, and the active terminal device 110-N. For the purpose of discussion, the signaling flow 200 is described with reference to Figure 1 . Additionally, for ease of description, the terminal device 110-n can be regarded as a representative of the active terminal devices.

[0056] In step 200, synchronizing the UAD is achieved by using a set of conjugate symmetric sequences. To this end, a set of terminal devices 110-1 to 110-N are pre-allocated a set of conjugate symmetric sequences and common time-frequency resources for the transmission of the corresponding conjugate symmetric sequences.

[0057] The terminal device 110-1 receives 205 from the network device 120 the configuration for allocating common time-frequency resources to the set of terminal devices 110-1 to 110-N in the radio access network and the configuration associating the set of terminal devices with a set of conjugate symmetric sequences. Similarly, the terminal device 110-n and the terminal device 110-N also receive 210, 215 similar configurations from the network device 120. In some examples of the embodiments, the configurations indicated by 205, 210, and 215 can be combined and transmitted from the network device 120 in a broadcast manner.

[0058] As an example, the common time-frequency resources can include M Resource Elements (REs) in a coherent block, and each RE carries one symbol of the conjugate symmetric sequence encoded by the terminal device 110.

[0059] For example, the terminal device 110-n, where n = 1, 2, …, N, can be pre-assigned a conjugate symmetric sequence, and the conjugate symmetric sequence is represented by the vector where: where and M represents the length of the conjugate symmetric sequence. Without loss of generality, it is assumed that the length of the conjugate symmetric sequence is odd. f n represents the unique frequency parameter of the terminal device 110-n, and the unique frequency parameter satisfies 0 ≤ f n < 1 and for n ≠ k, f n ≠ f k . where the superscript (·) * represents conjugation. Each sequence includes M complex symbols, and the M complex symbols are respectively mapped to M REs for transmission.

[0060] The conjugate symmetric sequence s n can be a complex conjugate symmetric sine sequence with a variable frequency parameter f n . The conjugate symmetric sequence can be uniquely associated with the terminal device 110-n by associating the unique frequency parameter with the terminal device 110-n. In this way, different terminal devices can be distinguished by the frequency parameter without causing preamble conflicts.

[0061] As an example of an implementation, f n = (n - 1) / N or for 0 ≤ θ n < π / 2, f n = sin θ n . In addition, s n has a constant modulus such that for m = 0, 1, …, M - 1, and ||s n || 2 = 1.

[0062] In some example embodiments, the length M of the conjugate symmetric sequence can be greater than or equal to twice the number of active terminal devices (which can be the average number of active terminal devices), (i.e., 2 × E{|S A |}), regardless of the total number of terminal devices (i.e., N). E{·} represents the mathematical expectation and |·| represents the cardinality of the set.

[0063] Since the terminal device 110-n (as well as the terminal device 110-1 and the terminal device 110-N) becomes an active terminal device (i.e., ),the terminal device 110-n will transmit a conjugate symmetric sequence encoded using partial phase compensation, denoted as

[0064] In some example embodiments, the active terminal device 110-n may encode the conjugate symmetric sequence s using a partial phase compensation factor which may be determined as follows: n where represents the angle of a complex number, represents a partial estimate of h n and the power of the transmitted sequence is configured at the level of P n n In some example embodiments, the encoded conjugate symmetric sequence may be determined as or

[0065] In other words, the encoded conjugate symmetric sequence is generated by encoding the conjugate symmetric sequence associated with the terminal device 110-n using a partial phase compensation factor that compensates for the phase of the channel from the terminal device 110-n to the network device 120 (i.e., the UL channel) in the common time-frequency resource, and the phase of this channel is denoted as Therefore, the encoded transmission of the conjugate symmetric sequence indicates the activity information of the active terminal devices in the entire set of terminal devices.

[0066] To save spectrum resources, all N terminal devices (i.e., terminal devices 110-1 to 110-N) are allowed to share the common time-frequency resource including M resource elements (REs) for transmitting their allocated sequences. Thus, each of the terminal devices 110-1, 110-n, and 110-N transmits the encoded conjugate symmetric sequence to the network device 120 in the common time-frequency resource.

[0067] Figure 3 FIG. shows a schematic diagram of a resource mapping 300 for conjugate symmetric sequences with partial phase compensation according to some example embodiments of the present disclosure. As Figure 3 shown, the shared physical resource block (PRB) includes M resource elements, and each resource element carries one symbol denoted as In this way, the network device 120 can receive the synchronized and superimposed signals from a set of active terminal devices S A and the baseband version of the synchronized and superimposed signals can be written as a vector of length M: where It represents additive noise including inter-cell interference, and r represents the superimposed conjugate symmetric sequence received by network device 120.

[0068] Considering that each terminal device 110-n may not possess the complete information of the phase of the UL channel but has a partial estimate thereof of the phase The partial phase compensation factor is obtained based on the partial knowledge of the phase of the UL channel. In particular, the partial estimate can be regarded as a rough estimate, and the allowable estimation error can be as high as such that the absolute deviation of the partial estimate satisfies In some example embodiments, the partial estimate can be obtained for the estimation of the phase of the corresponding DL channel. In other words, the partial phase compensation factor is determined based on the estimation of the phase of the channel from network device 120 to terminal device 110-n in the common time-frequency resource and the channel reciprocity between the transmission pairs of terminal device 110-n and network device 120.

[0069] On the terminal device side, the UL channel phase is partially compensated by the partial knowledge where the residual phase can be tolerated within a wide range In other words, the partial phase compensation factor can be determined based on the partial estimate of the phase of the channel from terminal device 110 to network device 120 in the common time-frequency resource, where the absolute deviation of the partial estimate is less than half of π in radians. It can be seen that the tolerable error range is so loose and occupies half of the complex plane.

[0070] Since the active terminal device 110-1, the active terminal device 110-n, and the active terminal device 110-N can adjust the transmission timing advance according to the prior knowledge of timing alignment, they are synchronized within the cyclic prefix. In this case, the active terminal device 110-1, the active terminal device 110-n, and the active terminal device 110-N transmit their respective encoded conjugate symmetric sequences in a synchronized manner based on the timing alignment information from network device 120. Therefore, the block fading assumption provides a reasonable model for the channel.

[0071] To this end, network device 120 can, for example, transmit a beacon signal at the beginning of each transmission period to indicate the transmission of the encoded conjugate symmetric sequence. This triggers the uplink transmission from the active terminal devices. The sequences transmitted from all the active terminal devices 110-1, the active terminal device 110-n, and the active terminal device 110-N arrive at network device 120 in a synchronized manner with respect to the receiving window of network device 120.

[0072] Thus, the network device 120 can observe a superimposed version of the encoded conjugate-symmetric sequences transmitted from all active terminal devices 110-n for n ∈ S A During transmission, no coordination between the terminal devices is required in the example embodiment. Each active terminal device acts independently according to its own scheduling request, and inactive terminal devices not belonging to S A (such as terminal devices 110-2 and 110-3) avoid any operation other than remaining silent. Note that the network device 120 has prior knowledge of the association pattern between a set of conjugate-symmetric sequences and a set of terminal devices 110-1 to 110-N, such that the network device 120 can identify the active terminal devices by detecting which conjugate-symmetric sequences are present in the superimposed observation.

[0073] Thus, the superimposed conjugate-symmetric sequence received at the network device 120 for UAD can be written as a vector r of length M as follows.

[0074] For the case of the vector r can be rewritten in a form indicating activity indicators associated with a set of terminal devices 110-1 to 110-N: where represents the received activity indicator associated with terminal device 110-n, and the activity indicator can be specified by

[0075] α n and P n both share the same indices of the non-zero entries caused by the active terminal devices 110-n for n ∈ S A Thus, the vector {α n} n∈S is a sparse vector. Only a few components are non-zero, corresponding to the active terminal devices 110-n for n ∈ S A

[0076] For the case of when partial phase compensation satisfies the real part of {α n} n∈S is always non-negative, i.e., for any n ∈ S, Re{α n} ≥ 0, where Re{·} represents the real part of a complex number. That is, {Re{α n}} n∈S ​is a sparse non - negative vector, where positive components indicate user activity and zeros indicate user inactivity. For the case of where the activity indicator symbol{α n} n∈S has a non - positive real part. In other words, the non - zero real parts of the activity indicator symbol{α n} n∈S have the same sign.

[0077] On the side of network device 120, after receiving a superimposed conjugate - symmetric sequence (i.e., r) associated with an encoded conjugate - symmetric sequence from a set of active terminal devices in a common time - frequency resource, network device 120 identifies a set of active terminal devices (i.e., S n} n∈S ) in a set of terminal devices (i.e., S A ) by solving for the activity indicator symbol (i.e.,{α

[0078] Specifically, network device 120 can identify active terminal devices by recovering N unknown{α n} n∈S from M mixed observations of the received vector r, where n > M. In fact, this involves an inverse problem regarding the observation model which can be rewritten in scalar form:

[0079] Essentially, this is an under - determined linear system in the case where the number of unknown variables is more than the number of equations, since S A is the unknown set to be identified. Although{α n} n∈S is sparse in the case of having many zero components, the non - zero components are usually complex numbers caused by the combined effect of channel experience and partial phase compensation.

[0080] To find the high - dimensional complex vector{α n} n∈S from low - dimensional raw received data, in some example embodiments, network device 120 can separately and serially estimate the real and imaginary parts of{α n} n∈S .

[0081] Specifically, for all terminal devices 110 - 1 to 110 - N, the real part{Re{α n}} n∈S can first be obtained by solving a large - scale sub - problem involving N - dimensional optimization variables. Based on the real part{Re{αn}} n∈S Estimation of S A A rough estimate of can be identified in the integrated set S. Rough estimate A low miss rate is pursued while tolerating a large false alarm rate. For this purpose, a relatively small decision threshold, i.e., β low , can be predefined as the first threshold such that as a rough estimate of the first group of identified active terminal devices can include almost all active terminal devices while inevitably including a certain number of inactive terminal devices. In particular, more than |S A | but much less than N and the knowledge of the rough estimate can be used for model order reduction. For the system obtained from formula (8) with N-dimensional unknowns, by removing the unknowns α for n the order can be reduced. Thus, a reduced-order linear observation model for dimensional unknowns can be obtained as

[0082] The system obtained from formula (9) is a deterministic system because is usually less than M. Such model order reduction overcomes the problem of dimensionality deficiency caused by insufficient measurement resources and enables a complete estimate for . In this way, network device 120 can easily obtain all the knowledge of α for by solving a small-scale subproblem involving dimensional optimization variables. Finally, all the knowledge of α n is used to further refine n and obtain the identified second group of active terminal devices.

[0083] Conjugate symmetry in sequence design enables network device 120 to easily eliminate the imaginary part of {α n} n∈S from the original received data r[m], resulting in the desired observation of the superimposed complex sine sequence depending only on the real part as where In some example embodiments, the superimposed complex sine sequence depending only on the imaginary part of {α n} n∈S can also be obtained from the original data r[m] in the following manner:

[0084] Furthermore, intentional partial phase compensation for conjugate symmetric sequences ensures that at In the case where, the real part of the unknown vector {α n} n∈S is restricted to be non - negative. This non - negative constraint on the unknowns facilitates solving from the transformed observations y[m] even though the system obtained from Equation (10) is still under - determined. In fact, the system of y[m] is shown to be a non - negative under - determined system. Fortunately, the designed complex sinusoidal sequence is crucial for capturing the entire information about the unknown vector using the minimum measurement resources. For the no - noise case, if 2|S A |≤M, then can be uniquely solved from the system obtained by formula (10).

[0085] This careful and systematic design enables a fast and accurate detection method for the network device 120 to recover when estimating the real parts of all potential terminal devices 110 - 1 to terminal device 110 - N A non - negative least - squares (LS) method is developed to solve. In addition, an L - MMSE (linear minimum mean - square error) method with non - negative constraints is designed to estimate for the dimensional unknowns. Finally, and all knowledge of is used to refine high via a strict threshold (e.g., β ) (as the second threshold) to reduce the false - alarm rate.

[0086] The detailed procedure of the proposed algorithm for the case is described below in Table 1. In step 5, for higher accuracy, the real part of the activity indicator associated with the identified first group of active terminal devices (i.e., ) is replaced with the corresponding real part obtained from the sparse non - negative vector . For the case, a similar algorithm can be obtained by replacing the non - negative constraints (i.e., x n ≤0 and Re{z n}≤0) in steps 2 and 4 with non - positive constraints. Table 1. Example Procedure of the UAD Algorithm

[0087] After identifying the active terminal devices, the network device 120 can then transmit 230 an indication of the identified set of active terminal devices (i.e., the refined ) to a group of terminal devices 110-1 to 110-N via a common channel. For example, the network device 120 can notify the identified active terminal devices of a mapping list. Each row of the list contains the ID of the identified terminal device and the associated scheduling grant. Although any one of the entire group of terminal devices 110-1 to 110-N can check the list, the network device 120 can allocate resources only for the identified terminal devices. By checking, the active terminal devices can determine whether they have been successfully identified by the network device 120.

[0088] In addition, the indication can also indicate the resources for the identified set of active terminal devices to perform communications respectively by the network device 120. Therefore, for the correctly identified active terminal device 110-n can perform communication with the network device 120 by using the corresponding resources associated with the terminal device 110-n for .

[0089] Therefore, in process 200, a group of terminal devices 110-1, terminal device 110-n, and terminal device 110-N can determine 235, 240, 245 whether the terminal devices are included in the set of active terminal devices identified by the network device 120 (i.e., the refined ).

[0090] If the detection is successful, the active terminal devices can continue to provide detailed scheduling information to the network device 120. As an example, the indication from the network device 120 indicates that terminal device 110-1 and terminal device 110-n are included in the set of active terminal devices identified by the network device 120.

[0091] In this case, based on the determination that terminal device 110-1 is included in the set of active terminal devices identified by the network device 120, terminal device 110-1 can perform 250 communication with the network device 120. Similarly, terminal device 110-n can perform 255 communication with the network device 120 based on a similar determination.

[0092] Otherwise, if the detection is unsuccessful, the active terminal devices can initiate a scheduling request by retransmitting their conjugate symmetric sequences with partial phase compensation in the next synchronization UAD opportunity.

[0093] In the above example, since the terminal device 110-N is not included in the set of active terminal devices identified by the network device 120, the terminal device 110-N is missed by the network device 120. In this case, the terminal device 110-N may re-transmit the encoded conjugate symmetric sequence 260 to the network device 120.

[0094] As one of various application scenarios, the conjugate symmetric sequence with partial phase compensation provided in the exemplary embodiments can be easily integrated with the scheduling request grant process. As an example, in such an integration process, all UEs can establish a class connection state without dedicated scheduling request resources. Then, the active UEs can initiate a scheduling request by transmitting their conjugate symmetric sequences with partial phase compensation separately and simultaneously in the common time-frequency resource. After receiving the superimposed conjugate symmetric sequence in the common time-frequency resource, the BS performs synchronous UAD. Then, the BS can give a scheduling grant for the identified UEs via the common DL control channel. The common DL control channel can be a low-rate DL control channel accessible by all UEs. Each active UE checks the DL control channel and determines whether the active UE has been identified as an active UE. Accordingly, the identified UEs provide detailed traffic demand information (such as a buffer status report) to the BS, while the missed UEs are degraded to initiate a scheduling request in the next synchronous UAD opportunity, for example, by re-transmitting the encoded conjugate symmetric sequence with partial phase compensation of the missed UEs.

[0095] It should be understood that some steps in the process 200 are optional or can be omitted, and the order of the steps is given for illustrative purposes. For example, steps 205 to 215 can be executed in parallel. Therefore, the embodiments of the present disclosure are not limited in this regard.

[0096] According to an exemplary embodiment of the present disclosure, a conjugate symmetric sequence {s n} n∈S is provided for accurate, fast, and scalable UAD such that the required sequence length M can be as small as twice the average number of active terminal devices (i.e., 2×E{|S A |}), regardless of how the total number of devices N scales. Utilizing the overall design from partial phase compensation, the communication system can benefit from the following advantages: ● Minimize the measurement cost required for perfect detection: Although the sequence length is less than the total number of potential users M < N, perfect synchronous UAD can be performed as long as the number of actual active terminal devices is less than M / 2. This perfect detection is deterministic in the absence of noise. ● Scalability for large-scale access: The measurement resources required for perfect detection only depend on the number of actual active users and are independent of the total number of terminal devices, resulting in a scalable solution. ● Facilitates sparsity detection: Non-negativity introduces sparsity in a natural way. Thus, in the design of detection algorithms, regularization terms (usually adopted by compressive sensing) used to encourage sparsity can be avoided, leading to fast detection algorithms with finite-step calculations. ● The fixed allocation between preambles and users establishes a unique association, which not only avoids preamble collisions caused by random allocation but also saves additional processes for reporting user IDs. Example simulation results

[0097] Now, a performance comparison between synchronous UAD via conjugate symmetric sequences and PRACH via ZC sequences under the same time-frequency resources (e.g., one PRB including 241 REs) will be discussed. Tables 2 and 3 list the detailed simulation parameters and channel models respectively. For synchronous UAD, the zero correlation zone of the ZC sequence can be zero. This indicates that the ZC sequence of length 241 can provide 241 orthogonal sequences for synchronous users without ambiguity, which is more than the orthogonal sequences provided in PRACH for random access without timing alignment. UAD performance is evaluated according to the probabilities of missed detection and false alarm. The simulation results are obtained by averaging over 10,000 independent experiments. Table 2. Simulation settings Table 3. Channel model

[0098] Figure 4 Shows various UAD performances at different transmission probabilities. In particular, for synchronous UAD (S-UAD) via conjugate sequences with partial phase compensation, a transmission probability threshold of 12.5% can be observed, beyond which the detection performance severely degrades, and this performance is limited by the degrees of freedom. In fact, the threshold is consistent with M / 2N in the simulation case. The observation is consistent with the theoretical analysis regarding the perfect reconstruction condition.

[0099] Figure 4 The simulation results in show that, compared with existing PRACH schemes, the conjugate symmetric sequence with partial phase compensation provided by the exemplary embodiment can increase the number of supported concurrent random access users by more than 2.5 times. This superiority benefits from the overall design of the advanced algorithms of non-conflicting and complex conjugate symmetric sine sequences with partial phase compensation for UAD. In contrast, for PARCH, sequence conflicts from random selection remain the main cause of performance degradation. Example method

[0100] Figure 5 FIG. 500 is a flowchart of a method implemented at a terminal device according to some example embodiments of the present disclosure. For example, the terminal device may include a UE or the like. For the purpose of discussion, method 500 will be described from the perspective of the terminal device 110-1 in Figure 1 FIG.

[0101] At block 510, the terminal device 110-1 receives from a network device 120 in a radio access network a configuration for allocating a common time-frequency resource to a group of terminal devices 110-1 to 110-N in the radio access network and a configuration for associating the group of terminal devices 110-1 to 110-N with a group of conjugate symmetric sequences. The encoded transmission of the conjugate symmetric sequences indicates the activity information of a group of active terminal devices among the group of terminal devices 110-1 to 110-N.

[0102] In some example embodiments, the conjugate symmetric sequence may be a complex conjugate symmetric sine sequence with variable frequency parameters.

[0103] In some example embodiments, the length of the conjugate symmetric sequence may be greater than or equal to twice the number of the group of active terminal devices.

[0104] In some example embodiments, the conjugate symmetric sequence may be exclusively associated with the terminal device 110-1 by associating a unique frequency parameter with the terminal device 110-1.

[0105] At block 520, the terminal device 110-1 transmits an encoded conjugate symmetric sequence to the network device 120 in the common time-frequency resource.

[0106] In some example embodiments, transmitting the encoded conjugate symmetric sequence may include: generating the encoded conjugate symmetric sequence by encoding the conjugate symmetric sequence associated with the terminal device 110-1 by using a partial phase compensation factor for compensating the phase of the channel from the terminal device 110-1 to the network device 120 in the common time-frequency resource.

[0107] In some example embodiments, the partial phase compensation factor may be determined based on a partial estimate of the phase of the channel from the terminal device 110-1 to the network device 120 in the common time-frequency resource. The absolute deviation of the partial estimate is less than half of Pi in radians.

[0108] In some example embodiments, method 300 may further include: determining the partial phase compensation factor based on an estimate of the phase of the channel from the network device 120 to the terminal device 110-1 in the common time-frequency resource and the channel reciprocity between the transmission pairs of the terminal device 110-1 and the network device 120.

[0109] In some example embodiments, method 300 may further include: receiving, from network device 120, an indication of a set of active terminal devices identified by the network device; determining whether terminal device 110-1 is included in the set of active terminal devices identified by network device 120; based on the determination that terminal device 110-1 is included in the set of active terminal devices identified by the network device, performing communication with network device 120; or based on the determination that terminal device 110-1 is not included in the set of active terminal devices identified by network device 120, retransmitting the encoded conjugate symmetric sequence to network device 120.

[0110] In some example embodiments, the indication may also be used to indicate resources for the set of active terminal devices identified by network device 120 to perform communication respectively, and terminal device 110-1 performs communication with network device 120 by using the corresponding resources associated with terminal device 110-1.

[0111] In some example embodiments, transmitting the encoded conjugate symmetric sequence may include: transmitting the encoded conjugate symmetric sequence in a synchronous manner based on the timing alignment information from network device 120.

[0112] Figure 6 A flowchart of an example method 600 implemented at a network device according to some example embodiments of the present disclosure is shown. For example, the network element may include a gNB or the like. For the purpose of discussion, method 600 will be described from Figure 1 the perspective of network device 120 in

[0113] At 610, network device 120 transmits to a set of terminal devices 110-1 to 110-N in a radio access network a configuration for allocating common time-frequency resources to the set of terminal devices 110-1 to 110-N and a configuration for associating the set of terminal devices 110-1 to 110-N with a set of conjugate symmetric sequences. The encoded transmission of the conjugate symmetric sequence indicates the activity information of a set of active terminal devices among the set of terminal devices 110-1 to 110-N.

[0114] In some example embodiments, the conjugate symmetric sequence is a complex conjugate symmetric sine sequence with variable frequency parameters, and the length of the conjugate symmetric sequence is greater than or equal to twice the number of the set of active terminal devices.

[0115] At 620, network device 120 receives, in the common time-frequency resources, a superimposed conjugate symmetric sequence associated with the encoded conjugate symmetric sequence from a set of active terminal devices. The superimposed conjugate symmetric sequence includes activity indication symbols associated with the set of terminal devices 110-1 to 110-N.

[0116] In some example embodiments, the encoded conjugate-symmetric sequences are separately generated by encoding the conjugate-symmetric sequences associated with a set of active terminal devices by using partial phase compensation factors, which are used to compensate for the phase of the channels from the set of active terminal devices to the network device 120 in the common time-frequency resources.

[0117] In some example embodiments, the non-zero real parts of the activity indication symbols have the same sign.

[0118] At 630, the network device 120 identifies a set of active terminal devices from the set of terminal devices 110-1 to 110-N by solving the activity indication symbols from the superimposed conjugate-symmetric sequences.

[0119] In some example embodiments, identifying a set of active terminal devices may include: determining a superimposed complex sine sequence based on the superimposed conjugate-symmetric sequence and its conjugate symmetry, the superimposed complex sine sequence including the real parts of the activity indication symbols associated with the set of terminal devices 110-1 to 110-N and not including the imaginary parts of the activity indication symbols associated with the set of terminal devices 110-1 to 110-N; determining the first identified set of active terminal devices based on the superimposed complex sine sequence; and determining the second identified set of active terminal devices as the identified set of active terminal devices based on the superimposed conjugate-symmetric sequence and the first identified set of active terminal devices.

[0120] In some example embodiments, determining the first identified set of active terminal devices may include: determining a sparse non-negative vector representing the real parts of the activity indication symbols associated with the set of terminal devices 110-1 to 110-N based on the superimposed complex sine sequence; determining the effective non-zero components of the real parts of the activity indication symbols associated with the set of terminal devices 110-1 to 110-N by comparing the components of the sparse non-negative vector with a first predefined threshold; and determining the first identified set of active terminal devices based on the effective non-zero components of the real parts of the activity indication symbols associated with the set of terminal devices 110-1 to 110-N.

[0121] In some example embodiments, determining the sparse non-negative vector may include: solving a non-negative least squares problem based on the superimposed complex sine sequence and a set of conjugate-symmetric sequences.

[0122] In some example embodiments, determining the identified second set of active terminal devices may include: determining, based on an overlaid conjugate symmetric sequence, a low-dimensional complex vector representing an activity indicator symbol associated with the identified first set of active terminal devices; determining valid non-zero components of the activity indicator symbol associated with the identified first set of active terminal devices by comparing magnitudes of components of the low-dimensional complex vector with a second predefined threshold; and determining the identified second set of active terminal devices based on the valid non-zero components of the activity indicator symbol associated with the identified first set of active terminal devices.

[0123] In some example embodiments, the low-dimensional complex vector is determined under a constraint that non-zero real parts of the low-dimensional complex vector have the same sign.

[0124] In some example embodiments, method 600 may further include: replacing real parts of the activity indicator symbol associated with the identified first set of active terminal devices with corresponding real parts obtained from a sparse non-negative vector.

[0125] In some example embodiments, method 600 may further include: transmitting, via a common channel, an indication for indicating the identified set of active terminal devices to a group of terminal devices 110-1 to 110-N.

[0126] In some example embodiments, the indication indicates resources for communication to be respectively performed by each active terminal device in the identified set of active terminal devices.

[0127] Method 600 may further include: transmitting a beacon signal indicating transmission of an encoded conjugate symmetric sequence to a group of terminal devices 110-1 to 110-N. Example apparatus, device, and medium

[0128] In some example embodiments, a first device (e.g., Figure 1 terminal device 110-1 in Figure 1 ) capable of performing any one of methods 500 may include components for performing corresponding operations of method 500. The components may be implemented in any suitable form. For example, the components may be implemented in a circuit system or a software module. The first device may be implemented Figure 1 as or included in terminal device 110-1 in

[0129] In some example embodiments, the first device includes: components for receiving, at the first device in a radio access network, a configuration for allocating a common time-frequency resource to a group of first devices in the radio access network and a configuration for associating the group of first devices with a group of conjugate-symmetric sequences, wherein the encoded transmission of the conjugate-symmetric sequences indicates activity information of a group of active first devices in the group of first devices; and components for transmitting an encoded conjugate-symmetric sequence to the second device in the common time-frequency resource.

[0130] In some example embodiments, the conjugate-symmetric sequence is a complex conjugate-symmetric sinusoidal sequence with variable frequency parameters.

[0131] In some example embodiments, the length of the conjugate-symmetric sequence is greater than or equal to twice the number of the group of active first devices.

[0132] In some example embodiments, the conjugate-symmetric sequence is uniquely associated with the first device by associating a unique frequency parameter with the first device.

[0133] In some example embodiments, the components for transmitting the encoded conjugate-symmetric sequence include: components for generating the encoded conjugate-symmetric sequence by encoding the conjugate-symmetric sequence associated with the first device by using a partial phase compensation factor, the partial phase compensation factor being used to compensate for the phase of the channel from the first device to the second device in the common time-frequency resource.

[0134] In some example embodiments, the partial phase compensation factor is determined based on a partial estimate of the phase of the channel from the first device to the second device in the common time-frequency resource, wherein the absolute deviation of the partial estimate is less than half of Pi in radians.

[0135] In some example embodiments, the first device further includes: components for determining the partial phase compensation factor based on an estimate of the phase of the channel from the second device to the first device in the common time-frequency resource and the channel reciprocity between the transmission pairs of the first device and the second device.

[0136] In some example embodiments, the first device further includes: components for receiving, from the second device, an indication indicating a group of active first devices identified by the second device; components for determining whether the first device is included in the group of active first devices identified by the second device; components for performing communication with the second device based on a determination that the first device is included in the group of active first devices identified by the second device; or components for re-transmitting the encoded conjugate-symmetric sequence to the second device based on a determination that the first device is not included in the group of active first devices identified by the second device.

[0137] In some example embodiments, the indication is further used to indicate resources for a respective communication to be performed by a set of active first devices identified by a second device, and the first devices perform communication with the second device by using corresponding resources associated with the first devices.

[0138] In some example embodiments, the component for transmitting the encoded conjugate-symmetric sequence includes: transmitting the encoded conjugate-symmetric sequence in a synchronized manner based on timing alignment information from a second device.

[0139] In some example embodiments, a second device (e.g., Figure 1 the network device 120 in Figure 1 ) that can perform any one of the methods 600 may include components for performing corresponding operations of the method 600. The components may be implemented in any suitable form. For example, the components may be implemented in a circuit system or a software module. The second device may be implemented as Figure 1 the network device 120 in

[0140] In some example embodiments, the second device includes: components for transmitting, at a second device in a radio access network, a configuration for allocating common time-frequency resources to a set of first devices in the radio access network and a configuration for associating the set of first devices with a set of conjugate-symmetric sequences, wherein the encoded transmission of the conjugate-symmetric sequences indicates activity information of a set of first active devices among the set of first devices; components for receiving, in the common time-frequency resources, a superimposed conjugate-symmetric sequence associated with the encoded conjugate-symmetric sequence from the set of first active devices, wherein the superimposed conjugate-symmetric sequence includes activity indication symbols associated with the set of first devices; and components for identifying a set of first active devices among the set of first devices by solving out the activity indication symbols from the superimposed conjugate-symmetric sequence.

[0141] In some example embodiments, the conjugate-symmetric sequence is a complex conjugate-symmetric sine sequence with variable frequency parameters, and the length of the conjugate-symmetric sequence is greater than or equal to twice the number of the set of first active devices.

[0142] In some example embodiments, the encoded conjugate-symmetric sequences are respectively generated by encoding the conjugate-symmetric sequences associated with a set of first active devices by using partial phase compensation factors for compensating the phase of the channels from the set of first active devices to the second device in the common time-frequency resources.

[0143] In some example embodiments, the non-zero real parts of the activity indication symbols have the same sign.

[0144] In some example embodiments, the components for identifying a first set of active devices include: components for determining a superimposed complex sine sequence based on a superimposed conjugate symmetric sequence and its conjugate symmetry, where the superimposed complex sine sequence includes the real part of the activity indication symbols associated with a first set of devices and does not include the imaginary part of the activity indication symbols associated with the first set of devices; components for determining the identified first set of first active devices based on the superimposed complex sine sequence; and components for determining the identified second set of first active devices as the identified first set of first active devices based on the superimposed conjugate symmetric sequence and the identified first set of first active devices.

[0145] In some example embodiments, the components for determining the identified first set of first active devices include: components for determining a sparse non - negative vector representing the real part of the activity indication symbols associated with a first set of devices based on the superimposed complex sine sequence; components for determining the effective non - zero components of the real part of the activity indication symbols associated with the first set of devices by comparing the components of the sparse non - negative vector with a first predefined threshold; and components for determining the identified first set of first active devices based on the effective non - zero components of the real part of the activity indication symbols associated with the first set of devices.

[0146] In some example embodiments, a low - dimensional complex vector is determined under the constraint that the non - zero real parts of the low - dimensional complex vector have the same sign.

[0147] In some example embodiments, the components for determining the identified second set of first active devices include: components for determining a low - dimensional complex vector representing the activity indication symbols associated with the identified first set of first active devices based on the superimposed conjugate symmetric sequence; components for determining the effective non - zero components of the activity indication symbols associated with the identified first set of first active devices by comparing the magnitudes of the components of the low - dimensional complex vector with a second predefined threshold; and components for determining the identified second set of first active devices based on the effective non - zero components of the activity indication symbols associated with the identified first set of first active devices.

[0148] In some example embodiments, a low - dimensional complex vector is determined under the constraint that the non - zero real parts of the low - dimensional complex vector have the same sign.

[0149] In some example embodiments, the second device further includes: components for replacing the real part of the activity indication symbols associated with the identified first set of first active devices with the corresponding real part obtained from the sparse non - negative vector.

[0150] In some example embodiments, the second device further includes: components for transmitting, via a common channel, an indication for indicating the identified first set of first active devices to a first set of devices.

[0151] In some example embodiments, the indication indicates resources for communication to be performed respectively by each of a set of identified first active devices.

[0152] In some example embodiments, the second device further includes: means for transmitting a beacon signal indicating the transmission of an encoded conjugate symmetric sequence to a set of first devices.

[0153] Figure 7 is a simplified block diagram of a device 700 suitable for implementing example embodiments of the present disclosure. The device 700 may be provided to implement an electronic device, for example, Figure 1 the terminal device 110 or the network device 120 shown in FIG. As shown, the device 700 includes one or more processors 710, one or more memories 720 coupled to the processor 710, and one or more communication modules 740 coupled to the processor 710.

[0154] The communication module 740 is for two-way communication. The communication module 740 has one or more communication interfaces to facilitate communication with one or more other modules or devices. The communication interface may represent any interface necessary for communicating with other network elements. In some example embodiments, the communication module 740 may include at least one antenna.

[0155] As a non-limiting example, the processor 710 may be of any type suitable for a local technical network and may include one or more of the following: a general-purpose computer, a special-purpose computer, a microprocessor, a digital signal processor (DSP), and a processor based on a multi-core processor architecture. The device 700 may have multiple processors, such as an application-specific integrated circuit chip that is subordinate to the clock of a synchronous main processor in time.

[0156] The memory 720 may include one or more non-volatile memories and one or more volatile memories. Examples of non-volatile memories include, but are not limited to, read-only memory (ROM) 724, electrically programmable read-only memory (EPROM), flash memory, hard disk, laser disc (CD), digital video disc (DVD), optical disc, laser disc, and other magnetic memories and / or optical memories. Examples of volatile memories include, but are not limited to, random access memory (RAM) 722 and other volatile memories that do not persist during a power outage duration.

[0157] The computer program 730 includes computer-executable instructions executed by the associated processor 710. The instructions of the program 730 may include instructions for performing operations / actions of some example embodiments of the present disclosure. The program 730 may be stored in a memory, such as ROM 724. The processor 710 may execute any suitable actions and processes by loading the program 730 into RAM 722.

[0158] Example embodiments of the present disclosure can be implemented by means of program 730 such that device 700 can execute any process of the present disclosure as discussed with reference to Figures 3 to 6 the present disclosure. Example embodiments of the present disclosure can also be implemented by hardware or by a combination of software and hardware.

[0159] In some example embodiments, program 730 can be tangibly embodied in a computer-readable medium, which can be included in device 700 (such as in memory 720) or other storage devices accessible by device 700. Device 700 can load program 730 from the computer-readable medium into RAM 722 for execution. In some example embodiments, the computer-readable medium can include any type of non-transitory storage medium, such as ROM, EPROM, flash memory, hard disk, CD, and DVD, etc. As used herein, the term "non-transitory" is a limitation of the medium itself (i.e., tangible, rather than a signal), rather than a limitation on data storage persistence (e.g., RAM versus ROM).

[0160] Figure 8 An example of computer-readable medium 700 is shown, which can be in the form of a CD, DVD, or other optical storage disk. Program 730 is stored on computer-readable medium 700.

[0161] Generally, the various embodiments of the present disclosure can be implemented in hardware or special-purpose circuitry, software, logic, or any combination thereof. Some aspects can be implemented in hardware, while other aspects can be implemented in firmware or software executable by a controller, microprocessor, or other computing device. Although the various aspects of the embodiments of the present disclosure are shown and described as block diagrams, flowcharts, or using some other graphical representation, it should be understood that, by way of non-limiting example, the blocks, devices, systems, techniques, or methods described herein can be implemented in hardware, software, firmware, special-purpose circuitry or logic, general-purpose hardware or a controller or other computing device, or some combination thereof.

[0162] Some example embodiments of the present disclosure also provide at least one computer program product tangibly stored on a computer-readable medium, such as a non-transitory computer-readable medium. The computer program product includes computer-executable instructions, such as those included in program modules executed in a device on a target physical or virtual processor, to perform any of the methods described above. Generally, program modules include routines, programs, libraries, objects, classes, components, or data structures, etc. that perform particular tasks or implement particular abstract data types. In various embodiments, the functionality of the program modules may be combined or split among the program modules as needed. The machine-executable instructions for the program modules may be executed within a local or distributed device. In a distributed device, the program modules may be located in both local and remote storage media.

[0163] The program code for implementing the methods of the present disclosure can be written in any combination of one or more programming languages. The program code can be provided to a processor or controller of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus, such that the program code, when executed by the processor or controller, causes the functions / operations specified in the flowchart and / or block diagram to be implemented. The program code can be executed entirely on the machine, partially on the machine, as a stand-alone software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0164] In the context of the present disclosure, the computer program code or related data can be carried by any suitable carrier so that a device, apparatus, or processor can perform the various processes and operations described above. Examples of carriers include signals, and computer-readable media, etc.

[0165] The computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. The computer-readable medium can include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or apparatuses, or any suitable combination of the foregoing. More specific examples of the computer-readable storage medium will include an electrical connection having one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0166] Moreover, although the operations are depicted in a particular order, this should not be construed as requiring that the operations be performed in the particular order shown or in sequential order, or that all of the illustrated operations be performed to achieve the desired result. In some cases, multitasking and parallel processing may be advantageous. Similarly, although several specific implementation details are included in the above discussion, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment, unless expressly stated otherwise. Conversely, various features that are described in the context of a single embodiment may also be implemented separately or in any suitable sub-combination in multiple embodiments, unless expressly stated otherwise.

[0167] Although the present disclosure has been described in language specific to structural features and / or methodological acts, it is to be understood that the disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the above specific features and acts are disclosed as example forms of implementing the claims.

Claims

1. A terminal device in a radio access network, comprising: at least one processor; and at least one memory storing instructions which, when executed by the at least one processor, cause the terminal device to at least: receive from a network device in the radio access network a configuration for allocating common time-frequency resources to a group of terminal devices in the radio access network and a configuration for associating the group of terminal devices with a group of conjugate symmetric sequences, wherein the encoded transmission of the conjugate symmetric sequences indicates activity information of a group of active terminal devices in the group of terminal devices; and transmit an encoded conjugate symmetric sequence to the network device on the common time-frequency resources.

2. The terminal device according to claim 1, wherein the conjugate symmetric sequence is a complex conjugate symmetric sine sequence with variable frequency parameters.

3. The terminal device according to claim 1 or claim 2, wherein the length of the conjugate symmetric sequence is greater than or equal to twice the number of the group of active terminal devices.

4. The terminal device according to claim 1 or claim 2, wherein the conjugate symmetric sequence is uniquely associated with the terminal device by associating a unique frequency parameter with the terminal device.

5. The terminal device according to claim 1, wherein the terminal device is caused to transmit the encoded conjugate symmetric sequence by: generating the encoded conjugate symmetric sequence by encoding the conjugate symmetric sequence associated with the terminal device by using a partial phase compensation factor for compensating the phase of the channel from the terminal device to the network device in the common time-frequency resources.

6. The terminal device according to claim 5, wherein the partial phase compensation factor is determined based on a partial estimate of the phase of the channel from the terminal device to the network device in the common time-frequency resources, wherein the absolute deviation of the partial estimate is less than half of Pi in radians.

7. The terminal device according to claim 5 or claim 6, wherein the terminal device is further caused to: determine the partial phase compensation factor based on an estimate of the phase of the channel from the network device to the terminal device in the common time-frequency resources and channel reciprocity between the transmission pairs of the terminal device and the network device.

8. The terminal device according to claim 1, wherein the terminal device is further caused to: receive from the network device an indication of a group of active terminal devices identified by the network device; determine whether the terminal device is included in the group of active terminal devices identified by the network device; perform communication with the network device based on a determination that the terminal device is included in the group of active terminal devices identified by the network device; or re-transmit the encoded conjugate symmetric sequence to the network device based on a determination that the terminal device is not included in the group of active terminal devices identified by the network device.

9. The terminal device according to claim 8, wherein the indication is further used to indicate resources for the respective execution of the communication by the set of active terminal devices identified by the network device, and the terminal device executes the communication with the network device by using corresponding resources associated with the terminal device.

10. The terminal device according to claim 1, wherein the terminal device is caused to transmit the encoded conjugate symmetric sequence by: transmitting the encoded conjugate symmetric sequence in a synchronized manner based on timing alignment information from the network device.

11. A network device in a radio access network, comprising: at least one processor; and at least one memory storing instructions which, when executed by the at least one processor, cause the network device to at least: transmit to a set of terminal devices in the radio access network a configuration for allocating common time-frequency resources to the set of terminal devices and a configuration for associating the set of terminal devices with a set of conjugate symmetric sequences, wherein the encoded transmission of the conjugate symmetric sequences indicates activity information of a set of active terminal devices among the set of terminal devices; receive, in the common time-frequency resources, a superimposed conjugate symmetric sequence associated with the encoded conjugate symmetric sequence from the set of active terminal devices, wherein the superimposed conjugate symmetric sequence includes activity indication symbols associated with the set of terminal devices; and identify the set of active terminal devices among the set of terminal devices by solving out the activity indication symbols from the superimposed conjugate symmetric sequence.

12. The network device according to claim 11, wherein the conjugate symmetric sequence is a complex conjugate symmetric sine sequence with variable frequency parameters, and the length of the conjugate symmetric sequence is greater than or equal to twice the number of the set of active terminal devices.

13. The network device according to claim 11, wherein the encoded conjugate symmetric sequences are respectively generated by encoding the conjugate symmetric sequences associated with the set of active terminal devices by using partial phase compensation factors for compensating the phase of the channels from the set of active terminal devices to the network device in the common time-frequency resources.

14. The network device according to claim 11, wherein non-zero real parts of the activity indication symbols have the same sign.

15. The network device according to claim 11, wherein the network device is caused to identify the set of active terminal devices by: determining a superimposed complex sine sequence based on the superimposed conjugate symmetric sequence and its conjugate symmetry, the superimposed complex sine sequence including real parts of the activity indication symbols associated with the set of terminal devices and not including imaginary parts of the activity indication symbols associated with the set of terminal devices; determining a first identified set of active terminal devices based on the superimposed complex sine sequence; and determining a second identified set of active terminal devices as the identified set of active terminal devices based on the superimposed conjugate symmetric sequence and the first identified set of active terminal devices.

16. The network device according to claim 15, wherein the network device is caused to determine the identified first set of active terminal devices by: Based on the superimposed complex sine sequence, determining a sparse non - negative vector representing the real part of the activity indicator symbols associated with the set of terminal devices; By comparing the components of the sparse non - negative vector with a first predefined threshold, determining the effective non - zero components of the real part of the activity indicator symbols associated with the set of terminal devices; and Based on the effective non - zero components of the real part of the activity indicator symbols associated with the set of terminal devices, determining the identified first set of active terminal devices.

17. The network device according to claim 16, wherein the network device is caused to determine the sparse non - negative vector by: Solving a non - negative least - squares problem based on the superimposed complex sine sequence and the set of conjugate - symmetric sequences.

18. The network device according to claim 15, wherein the network device is caused to determine the identified second set of active terminal devices by: Based on the superimposed conjugate - symmetric sequence, determining a low - dimensional complex vector representing the activity indicator symbols associated with the identified first set of active terminal devices; By comparing the magnitudes of the components of the low - dimensional complex vector with a second predefined threshold, determining the effective non - zero components of the activity indicator symbols associated with the identified first set of active terminal devices; and And Based on the effective non - zero components of the activity indicator symbols associated with the identified first set of active terminal devices, determining the identified second set of active terminal devices.

19. The network device according to claim 18, wherein the low - dimensional complex vector is determined under the constraint that the non - zero real parts of the low - dimensional complex vector have the same sign.

20. The network device according to claim 18, wherein the network device is further caused to: Replace the real part of the activity indicator symbols associated with the identified first set of active terminal devices with the corresponding real part obtained from the sparse non - negative vector.

21. The network device according to any one of claims 11 to 20, wherein the network device is further caused to: Transmit, via a common channel, an indication for indicating the identified set of active terminal devices to the set of terminal devices.

22. The network device according to claim 21, wherein the indication indicates resources for communication to be performed respectively by each active terminal device in the identified set of active terminal devices.

23. The network device according to any one of claims 11 to 20, wherein the network device is further caused to: Transmit a beacon signal indicating the transmission of the encoded conjugate - symmetric sequence to the set of terminal devices.

24. A method, comprising: At a terminal device in a radio access network, receive, from a network device in the radio access network, a configuration for allocating a common time-frequency resource to a group of terminal devices in the radio access network and a configuration for associating the group of terminal devices with a group of conjugate symmetric sequences, wherein the encoded transmission of the conjugate symmetric sequences indicates activity information of a group of active terminal devices in the group of terminal devices; And Transmit, in the common time-frequency resource, an encoded conjugate symmetric sequence to the network device.

25. A method includes: At a network device in a radio access network, transmit, to a group of terminal devices in the radio access network, a configuration for allocating a common time-frequency resource to the group of terminal devices and a configuration for associating the group of terminal devices with a group of conjugate symmetric sequences, wherein the encoded transmission of the conjugate symmetric sequences indicates activity information of a group of active terminal devices in the group of terminal devices; Receive, in the common time-frequency resource, from the group of active terminal devices, a superimposed conjugate symmetric sequence associated with the encoded conjugate symmetric sequence, wherein the superimposed conjugate symmetric sequence includes activity indication symbols associated with the group of terminal devices; And Identify the group of active terminal devices in the group of terminal devices by solving the activity indication symbols from the superimposed conjugate symmetric sequence.

26. A first apparatus includes: Components for receiving, at the first apparatus in a radio access network, from a second apparatus in the radio access network, a configuration for allocating a common time-frequency resource to a group of first apparatuses in the radio access network and a configuration for associating the group of first apparatuses with a group of conjugate symmetric sequences, wherein the encoded transmission of the conjugate symmetric sequences indicates activity information of a group of first active apparatuses in the group of first apparatuses; And Components for transmitting, in the common time-frequency resource, an encoded conjugate symmetric sequence to the second apparatus.

27. A second apparatus includes: Components for transmitting, at the second apparatus in a radio access network, to a group of first apparatuses in the radio access network, a configuration for allocating a common time-frequency resource to the group of first apparatuses and a configuration for associating the group of first apparatuses with a group of conjugate symmetric sequences, wherein the encoded transmission of the conjugate symmetric sequences indicates activity information of a group of first active apparatuses in the group of first apparatuses; Components for receiving, in the common time-frequency resource, from the group of active first apparatuses, a superimposed conjugate symmetric sequence associated with the encoded conjugate symmetric sequence, wherein the superimposed conjugate symmetric sequence includes activity indication symbols associated with the group of first apparatuses; And Components for identifying the group of first active apparatuses in the group of first apparatuses by solving the activity indication symbols from the superimposed conjugate symmetric sequence.

28. A computer-readable medium includes program instructions for causing a device to execute the method according to claim 24 or claim 25.

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