Method and wireless communication system for energy saving coverage enhancement

Abstract

A method for energy saving coverage enhancement (CE), the method comprising the steps of: when a user equipment (UE) is in idle mode, the user equipment (UE) deciding whether to switch to an alternative network based on overall network congestion, where the information is indicated by the network by a maximum random access (RA) procedure failure reaching a coverage enhancement (CE) level (k), and performing a cell selection on the alternative network, verifying the coverage of the cell, and if the coverage of the cell is sufficient, then the user equipment (UE) switches to the alternative network and performs a random access (RA) procedure, the user equipment (UE) remains in the same network and upgrades from a previous level (k) to a coverage enhancement (CE) level (k + 1) for a subsequent random access (RA) procedure in the event of insufficient coverage of the cell.

Description

Technical Field

[0001] The present disclosure relates to energy-efficient coverage enhancement in wireless communication systems. Background Art

[0002] The 3rd Generation Partnership Project (3GPP) standardized Coverage Enhancement (CE) for the Internet of Things (IoT) to connect devices to cellular networks under challenging radio conditions. CE is based on the principle of extending transmission time, which exploits the fact that many IoT applications have relaxed requirements on data rate and latency, and can significantly improve coverage by repeating transmissions for such applications. However, CE consumes a lot of radio resources and should be implemented with caution for different applications.

[0003] The evolution of wireless communication technology to the fifth generation (5G) has enabled everything to be connected through the Internet. For example, a large amount of information related to human activities has been recorded and monitored through various types of IoT applications (e.g., health monitoring, smart home, smart transportation, industrial automation) and exchanged through cellular networks. Unfortunately, however, traditional cellular networks are not designed to accommodate such diverse IoT applications. Accordingly, great efforts have been made to support emerging IoT scenarios in cellular networks, namely, massive machine type communications (mMTC) or massive IoT (mIoT), which is one of the main use cases of 5G.

[0004] In cellular networks, a very large number of IoT devices are expected to be deployed, with the number of connected devices expected to reach 500 billion by 2030. Each IoT device sporadically generates small packets to report sensing information to the IoT server through the base station (BS / gNB). In particular, the IoT device remains disconnected from the BS to reduce energy consumption caused by sporadic packet generation. This means that each IoT device should perform a random access (RA) procedure to establish a connection with the BS whenever transmitting a data packet to the IoT server. The RA procedure adopted in existing cellular systems such as LTE / LTE-A / 5G consists of a four-step handshake procedure. Since IoT devices are densely deployed in cellular IoT networks, simultaneous RA attempts in a certain RA slot (or equivalently, physical RA channel (PRACH)) may cause collision problems. The collision problem is largely responsible for poor access performance (i.e., RA failure) on the device side. Specifically, IoT devices may take a lot of time to access the network, so the network cannot guarantee acceptable end-to-end delay according to their access priority.

[0005] In cellular systems, connectivity between each IoT device and the BS is a prerequisite for data communication. To establish connectivity, the device should perform a 4-step RA procedure. In summary, the overall description of the traditional RA procedure in cellular networks (e.g., LTE / LTE-A / 5G) is as follows:

[0006] Step 1. Preamble transmission: Each IoT device randomly selects a single RA preamble from a set of available RA preambles and transmits it on the PRACH.

[0007] Step 2. Random Access Response: The BS detects which preambles are active. In response to the detected preambles, the BS transmits a Random Access Response (RAR) message, each of which consists of a RA Preamble Identifier (RAPID), Timing Alignment (TA), Uplink Grant (UG), and a Temporary Identifier. Each IoT device that transmitted a preamble at the first step waits for a RAR message containing the same RAPID. If there is a corresponding RAR message, each device uses the information within the message for the subsequent step (i.e., step 3).

[0008] Step 3. Scheduling transmission: Each IoT device transmits its scheduling message (e.g., connection request message) on the assigned uplink resources on the physical uplink shared channel (PUSCH), which are indicated by the UG value contained in the RAR message received in step 2. In order to determine whether a resource conflict occurs on the used uplink resources, each IoT device starts a contention resolution (CR) timer upon transmitting the message of step 3.

[0009] Step 4. Acknowledgement: The BS transmits back the identifier of the IoT device whose transmitted scheduling message was successfully decoded without any resource conflict. If each IoT device receives a correct acknowledgement (ACK) message before the CR timer expires, it considers the RA attempt as successful. Otherwise, it considers the RA attempt as a failure and retries the RA procedure in the next available RA slot after performing a backoff.

[0010] US2022131602 A1 discloses a method, network node, and wireless device for reliable link performance of cellular Internet of Things (IoT) and New Radio (NR) in non-terrestrial networks. In some embodiments, a network node configured to operate in a cellular non-terrestrial network is provided. The network node includes a processing circuit system configured to provide an indication of transmission property information associated with reconfiguration of precoding weights, wherein the indication of the transmission property information provides information associated with decoding a physical downlink shared channel or a physical downlink control channel.

[0011] WO 2021204079 A1 describes methods, systems, and devices for wireless communications, in which the block error rate (BLER) in non-terrestrial network (NTN) communications can be reduced by coverage enhancement techniques. Coverage enhancement techniques may include time slot bundling for physical downlink control channel (PDCCH) communications, wherein the repetition of the PDCCH may occupy multiple time-frequency positions across multiple time slots. Such time slots may be continuous or non-continuous, and in some cases, multiple repetitions of the PDCCH may be provided within the same time slot. The pattern of repeated time-frequency positions may be periodic or aperiodic. In addition, the repetition may be an exact copy or a different redundant version of the same coded DCI. Additionally, repetitions of uplink or downlink shared channel communications, uplink or downlink control channel communications, broadcast channel communications, or any combination thereof may be provided.

[0012] CN 113644950 discloses a non-terrestrial network (NTN) communication method and a non-terrestrial network communication device, which are used to solve the following problem: when a UE (user equipment) performs a communication service that is sensitive to time delay, it is impossible to distinguish between a cell covered by a ground base station and a cell covered by a satellite, and may select a cell covered by a satellite. The method includes the following steps: a first network device determines the cell type information of a cell covered by a second network device, and the cell type information is used to indicate whether the cell is a terrestrial network communication cell or a non-terrestrial network communication cell. And the first network equipment sends the cell type information to a third network equipment. In an embodiment of the present invention, when an interface connection is established between the first network equipment and the third network equipment in an NTN scenario, the relevant NTN indication (i.e., the cell type information of the second network equipment) is carried, so that the third network equipment can further know the capabilities and characteristics of the first network equipment.

[0013] US2021194572 A1 provides a UE parameter determination method and device, storage medium and base station. The method includes: determining the minimum round-trip time between each UE in the cell and the satellite; determining the frame information of the network side uplink radio frame based on the minimum round-trip time and the frame information of the network side downlink radio frame, wherein the minimum round-trip time is the timing difference of the network side uplink radio frame lagging behind the network side downlink radio frame; and determining the UE parameters of each UE based on the network side uplink radio frame and the network side downlink radio frame, wherein the UE parameters include at least one of TA or K2. Through this method, the NTN network can be supported under the premise of minimizing the modification of the software and hardware of the ground network UE, thereby effectively avoiding the additional maintenance costs of software and hardware.

[0014] WO 2022082771 A1 describes a beam management for a non-terrestrial network (NTN). An example aspect is a baseband processor, the baseband processor comprising: a memory interface; and a process, the process is communicatively coupled to the memory and the transceiver interface and simultaneously connected to a base station (BS) within a cell of the non-terrestrial network (NTN), and wherein the cell comprises a plurality of bandwidth parts (BWPs) associated with a plurality of beams, the process is configured to perform operations, the operations comprising: receiving from the base station (BS) signaling comprising a channel state indicator reference signal (CSI-RS) configuration associated with a first BWP in a plurality of BWPs, wherein the CSI-RS configuration comprises a beam measurement configuration for a plurality of beams, switching from a second BWP in a plurality of BWPs to a first BWP according to the CSI-RS configuration and measuring one or more beams in the plurality of beams according to the beam measurement configuration; and generating a measurement report comprising a layer 1 reference signal received power (L1-RSRP) measurement value according to the measured one or more beams in the plurality of beams.

[0015] US2021306927 A1 describes a method for operating infrastructure equipment that forms part of a wireless communication network. The wireless communication network includes a base station and a non-terrestrial network portion, which transmits one or more spot beams to provide a wireless access interface, which is used to transmit signals to a communication device within the coverage area of ​​a cell or one of these spot beams and receive signals representing data from the communication device, and the spot beam forms a cell. The method includes: transmitting an indication of a first condition to be met to the communication device before the communication device should transmit auxiliary information to the infrastructure equipment; receiving auxiliary information from the communication device when the first condition is met; determining that a cell change of the communication device should be initiated based on the auxiliary information; and initiating a cell change of the communication device.

[0016] The technology discussed in WO 2022082662 A1 can better ensure the correct timing and synchronization of transmissions within wireless communication networks, including terrestrial networks and non-terrestrial networks (NTNs). A user equipment (UE) can maintain (e.g., continuously determine and update) a timing advance (TA) value, which the UE can apply to uplink (UL) transmissions to account for propagation delays (including variations in propagation delays) between the UE, NTN, and terrestrial networks. TA maintenance can be based on network broadcasts, random access channel (RACH) procedures, control messages, timing drift rates (e.g., of UE or NTN satellites), beam switching, etc.

[0017] WO 2022082744 A1 discloses a user equipment (UE) associated with a non-terrestrial network (NTN). The UE includes a processor configured to determine a first time offset based on processing a timing offset indication signal received from a base station, the timing offset indication signal including the first time offset or an associated parameter. In some embodiments, the first time offset indicates a time delay in a downlink (DL) to uplink (UL) interaction between the UE and the base station. The processor is further configured to determine a second time offset based on processing a subsequent timing offset indication signal received from the base station at a subsequent time, the subsequent timing offset indication signal including the second time offset or an associated parameter. In some embodiments, the processor is further configured to update the first time offset using the second time offset.

[0018] WO 2021156749 A1 describes a method performed by a wireless device, the method comprising obtaining a remaining service time (Tservice) associated with a first satellite or a first spot beam. Based on the remaining service time, the wireless device determines whether to initiate a connection with the first satellite or the first spot beam.

[0019] Massive IoT is a technology that supports large numbers of devices, long device battery life, low device complexity to ensure low costs, and coverage enhancement to reach devices located in challenging locations (forests, basements, etc.).

[0020] LPWAN is a wireless technology designed for long-range, low-bit-rate, and battery-powered IoT devices, especially large-scale IoT devices. NB-IoT is a cellular IoT technology introduced by 3GPP to meet LPWAN requirements.

[0021] Power saving mechanisms are designed to improve the energy efficiency of UEs. UE battery life determines the UE lifetime (NB-IoT), and the expected IoT device lifetime is more than 10 years.

[0022] 3gpp has introduced power saving mechanisms (UE) (DRx, eDRx, RAI, WuS) to improve UE energy efficiency.

[0023] The longer large-scale IoT devices remain in poor coverage conditions, the higher the energy consumption, because the higher the coverage enhancement (CE) level, the shorter the battery life. Summary of the invention

[0024] The main goal of this application is to provide a solution for all opportunities for massive IoT devices (UE) to maintain communication at lower coverage enhancement (CE) levels.

[0025] The described problem is solved by embodiments of the present application.

[0026] According to a specific embodiment, a method for energy-saving coverage enhancement (CE) is characterized by a user equipment (UE) device connected to a wireless communication network, wherein, in the event of failure to reach a maximum random access (RA) procedure, the user equipment (UE) decides whether to upgrade to a higher level of coverage enhancement (CE) or switch networks.

[0027] A specific embodiment is characterized by a method for energy-saving coverage enhancement (CE), the method comprising the following steps: a user equipment (UE) is in idle mode, the user equipment (UE) decides whether to switch to an alternative network based on overall network congestion, wherein the information is indicated by the network through a maximum random access (RA) procedure failure to reach coverage enhancement (CE) level (k), a cell selection on the alternative network is performed, the coverage of the cell is verified, and if the coverage of the cell is sufficient, the user equipment (UE) switches to the alternative network and performs a random access (RA) procedure, and if the coverage of the cell is insufficient, the user equipment (UE) remains in the same network and is upgraded from coverage enhancement (CE) level (k) to level (k+1) for the random access (RA) procedure.

[0028] According to a specific embodiment, the method for energy-saving coverage enhancement (CE) includes the following steps: a user equipment (UE) is in a connected mode, and the user equipment (UE) decides whether to switch to an alternative network based on overall network congestion, wherein the decision information is determined by the failure of the maximum random access (RA) procedure reaching the coverage enhancement (CE) level (k), and in the event of the failure of the maximum random access (RA) procedure reaching the coverage enhancement (CE) level (k), checking whether the user equipment (UE) should trigger a switch to the alternative network, and if the result of the check is positive, performing the switch to the alternative network, and if the result of the check is negative, the user equipment (UE) remains in the same network and is upgraded from the coverage enhancement (CE) level (k) to the level (k+1) for the random access (RA) procedure.

[0029] A particular embodiment is characterized by a method for Energy Efficient Coverage Enhancement (CE) according to claims 1 to 3, wherein, in the event of failure to reach a maximum Random Access (RA) procedure, the network switches from a terrestrial network to a non-terrestrial network (TN to NTN) or from a non-terrestrial network to a terrestrial network (NTN to TN).

[0030] A particular embodiment is characterized in that, wherein the user equipment (UE) is a user equipment for a narrowband Internet of Things UE (NB-IoT), when the user equipment is initially connected to a terrestrial network (TN), it considers utilizing a non-terrestrial network instead of a terrestrial network (NTN) before upgrading to a higher level of coverage enhancement (CE, CE 1, CE 2).

[0031] A particular embodiment is characterized in that, wherein the user equipment (UE) is a user equipment for a narrowband Internet of Things UE (NB-IoT), when the user equipment is initially connected to a non-terrestrial network instead of a terrestrial network (NTN), it considers utilizing a terrestrial network (TN) before upgrading to a higher level of coverage enhancement (CE, CE 1, CE 2).

[0032] A feature of a particular embodiment is that when the user equipment (UE) reaches a maximum random access (RA) procedure failure, the user equipment (UE) may consider switching to an alternative network instead of upgrading the coverage enhancement (CE) level (k), thereby reducing signaling overhead and / or reducing power consumption of the user equipment UE.

[0033] A particular embodiment of a method for energy-saving coverage enhancement (CE) by a base station (gNB) in a wireless communication network is characterized by the following steps: receiving a random access (RA) requesting coverage enhancement (CE), sending a notification to a user equipment (UE) in an idle mode state, and

[0034] The user equipment (UE) decides whether to switch to an alternative network based on the overall network congestion,

[0035] wherein the decision information is determined by a maximum random access (RA) procedure failure to reach a coverage enhancement (CE) level (k),

[0036] In case of failure to reach the maximum random access (RA) procedure for Coverage Enhancement (CE) Level (k),

[0037] checking whether a user equipment (UE) triggered handover to an alternative network should be performed,

[0038] If the result of this check is positive, the switch to the alternative network is performed,

[0039] If the result of this check is negative, the user equipment (UE) remains in the same network and is upgraded from coverage enhancement (CE) level (k) to level (k+1) for the random access (RA) procedure, whereby the base station (gNB) configures the user equipment (UE) whether to switch to an alternative network.

[0040] A particular embodiment of a method for energy-saving coverage enhancement (CE) by a base station (gNB) in a wireless communication network is characterized by the following steps: receiving a random access (RA) requesting coverage enhancement (CE), a notification to a user equipment (UE) in connected mode,

[0041] The user equipment (UE) decides whether to switch to an alternative network based on the overall network congestion, wherein the decision information is determined by the failure of the maximum random access (RA) procedure reaching the coverage enhancement (CE) level (k), and in the case of the failure of the maximum random access (RA) procedure reaching the coverage enhancement (CE) level (k), it is checked whether the user equipment (UE) should trigger the switch to the alternative network, if the result of the check is positive, the switch to the alternative network is performed, if the result of the check is negative, the user equipment (UE) remains in the same network and is upgraded from the coverage enhancement (CE) level (k) to the level (k+1) for the random access (RA) procedure, thereby the base station (gNB) configures the user equipment (UE) whether to switch to the alternative network.

[0042] A specific embodiment of a method for energy-saving coverage enhancement (CE) by a base station (gNB) in a wireless communication network is characterized by the following steps:

[0043] receiving a random access (RA) requesting a coverage enhancement (CE), notification to a user equipment (UE) in connected mode,

[0044] The user equipment (UE) decides whether to switch to an alternative network based on the overall network congestion, wherein the decision information is determined by the failure of the maximum random access (RA) procedure reaching the coverage enhancement (CE) level (k), and in the case of the failure of the maximum random access (RA) procedure reaching the coverage enhancement (CE) level (k), it is checked whether the user equipment (UE) should trigger the switch to the alternative network, if the result of the check is positive, the switch to the alternative network is performed, if the result of the check is negative, the user equipment (UE) remains in the same network and is upgraded from the coverage enhancement (CE) level (k) to the level (k+1) for the random access (RA) procedure, thereby the base station (gNB) configures the user equipment (UE) whether to switch to the alternative network.

[0045] Particular embodiments are characterized by an apparatus for receiving transmissions for energy-efficient coverage enhancement (CE) from a user equipment (UE) in a wireless communication network, the apparatus comprising a wireless transceiver, a processor coupled to a memory having computer program instructions stored therein, the instructions being configured to implement the steps of claims 1 to 7.

[0046] A particular embodiment is characterized by a device for receiving transmissions for energy-saving coverage enhancement (CE) from a base station (gnB) in a wireless communication network, the device comprising a wireless transceiver, a processor (602) coupled to a memory in which computer program instructions are stored, the instructions being configured to implement the steps of claims 8 to 9.

[0047] A particular embodiment features a user equipment (UE) comprising an apparatus according to claim 10 .

[0048] A particular embodiment features a base station comprising an arrangement according to claim 11 .

[0049] Particular embodiments are characterized by a wireless communication system for performing energy-efficient coverage enhancement from a base station to user equipment, wherein the base station comprises a processor coupled to a memory having computer program instructions stored therein, the instructions being configured to implement the steps of claims 8 to 9;

[0050] Therein, the user equipment (UE) comprises a processor coupled to a memory having computer program instructions stored therein, the instructions being configured to implement the steps of claims 1 to 7.

[0051] A particular embodiment is characterized by the wireless communication system for performing energy-saving coverage enhancement according to claim 14, wherein after the user equipment (UE) obtains handover decision information from at least one cell A to at least another cell B based on a defined criterion, the handover triggered by the user equipment (UE) is performed after performing the following steps:

[0052] The user equipment (UE) sends a random access (RA) request to cell A with a coverage enhancement (CE) level (k).

[0053] Cell A sends the random access (RA) failure coverage enhancement (CE) level (k) back to the user equipment (UE), and waits for the user equipment (UE) to connect with a higher coverage enhancement (CE) level (k).

[0054] The user equipment (UE) sends a random access (RA) request coverage enhancement (CE) level (k) to the cell B, and if the user equipment (UE) cannot perform random access (RA), the cell A buffers the data of the user equipment (UE).

[0055] Cell B sends a random access (RA) response coverage enhancement (CE) level (k) back to the user equipment (UE), and the user equipment (UE) and cell B are connected.

[0056] Cell B updates the details of the user equipment (UE). If cell A obtains updates about the user equipment (UE) from cell B, cell A transmits the data of the user equipment (UE) to the cell. If cell A does not obtain updates about the user equipment (UE) from other cells, cell A declares a radio link failure (RLF).

[0057] The information medium may be any entity or device capable of storing a program. For example, the medium may include a storage device such as a ROM (e.g., a CD ROM or a microelectronic circuit ROM), a FLASH memory, or any magnetic recording device (e.g., a hard disk drive).

[0058] Furthermore, the information medium may be a transmissible medium such as an electric or optical signal that may be transmitted via an electrical or optical cable, by radio or by other means.

[0059] Alternatively, the information medium may be an integrated circuit in which the program is contained, the circuit being adapted to carry out or for carrying out the method in question.

[0060] The advantages of the device, the user equipment, the wireless system, the computer program and the information medium are the same as presented with respect to the corresponding method according to any of the above described embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Other advantages and characteristics of the invention will become more apparent on reading the following description, given by way of simple illustrative and non-limiting examples, and the accompanying drawings, in which:

[0062] - Figure 1 Coverage Enhancement (CE) is shown;

[0063] - Figure 2a A successful RA is shown;

[0064] - Figure 2b Random access (RA) failure and retransmission are shown;

[0065] - Figure 3 The repetition of the preamble (CE) is shown;

[0066] - Figure 4 A flow chart showing a prior art Coverage Enhancement (CE) procedure;

[0067] - Figure 5 The flowchart of the first embodiment on the UE side is shown;

[0068] - Figure 6 The flowchart of the first embodiment on the gNB side is shown;

[0069] - Figure 7 The flowchart of the second embodiment on the UE side is shown;

[0070] - Figure 8 The flowchart of the second embodiment on the gNB side is shown;

[0071] - Fig. 9 A UE triggered handover is shown. DETAILED DESCRIPTION

[0072] The specific embodiments described below with reference to the accompanying drawings are intended as descriptions of various configurations and are not intended to represent the only configurations in which the concepts described herein may be practiced. The specific embodiments include specific details to provide a thorough understanding of the various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In particular, although terminology from 3GPP 5G NR may be used in this disclosure to illustrate the embodiments herein, this should not be viewed as limiting the scope of the invention.

[0073] Some embodiments contemplated herein will now be described more fully with reference to the accompanying drawings. However, other embodiments are also included within the scope of the subject matter disclosed herein, and the disclosed subject matter should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided by way of example to convey the scope of the subject matter to those skilled in the art.

[0074] Generally, all terms used herein should be interpreted according to their ordinary meaning in the relevant technical field, unless different meanings are clearly given and / or different meanings are implied from the context of their use. Unless otherwise clearly stated, all references to one / a kind / the element, device, part, mode, step, etc. should be openly interpreted as referring to at least one instance of an element, device, part, mode, step, etc. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless a step is clearly described as being after or before another step and / or it is implied that a step must be after or before another step. Where appropriate, any feature of any embodiment disclosed herein may be applicable to any other embodiment. Similarly, any advantage of any embodiment may be applicable to any other embodiment, and vice versa. According to the following description, other purposes, features and advantages of the attached embodiments will become apparent.

[0075] In some embodiments, a more general term "network node" may be used, which may correspond to any type of radio network node or any network node that communicates with a UE (directly or via another node) and / or communicates with another network node. Examples of network nodes are NodeB, MeNB, ENB, network nodes belonging to MCG or SCG, base stations (BS), multi-standard radio (MSR) radio nodes (such as MSR BS, eNodeB, gNodeB), network controllers, radio network controllers (RNC), base station controllers (BSC), relays, donor node controlled relays, base transceiver stations (BTS), access points (AP), transmission points, transmission nodes, RRUs, RRHs, nodes in distributed antenna systems (DAS), core network nodes (such as mobile switching centers (MSCs), mobile management entities (MMEs), etc.), operations and maintenance (O&M), operations support systems (OSS), self-optimizing networks (SONs), positioning nodes (such as evolved serving mobile positioning centers (E-SMLCs)), minimization of drive tests (MDTs), test equipment (physical nodes or software), etc.

[0076] In some embodiments, the non-limiting term user equipment (UE) or wireless device may be used and may refer to any type of wireless device that communicates with a network node and / or another UE in a cellular or mobile communication system. Examples of UEs are target devices, device-to-device (D2D) UEs, machine-type UEs or UEs capable of machine-to-machine (M2M) communication, PDAs, PADs, tablet computers, mobile terminals, smart phones, laptop embedded devices (LEEs), laptop mounted equipment (LMEs), USB dongles, M1 class UEs, M2 class UEs, ProSe UEs, V2V UEs, V2X UEs, etc.

[0077] In addition, terms such as base station / gNodeB and UE should be considered non-restrictive and in particular do not imply a certain hierarchical relationship between the two; generally, "gNodeB" can be considered as device 1, "UE" can be considered as device 2, and the two devices communicate with each other through a certain radio channel. And in the following, a transmitter or a receiver can be a gNodeB (gNB) or a UE.

[0078] Narrowband Internet of Things (NB-IoT) is a low-power wide area network (LPWAN) radio technology standard developed by 3GPP for cellular devices and services. The specification was frozen in 3GPP Release 13 (LTE Advanced Pro) in June 2016. Other 3GPP IoT technologies include eMTC (enhanced machine type communication) and EC-GSM-IoT. NB-IoT pays special attention to indoor coverage, low cost, long battery life and high connection density. NB-IoT uses a subset of the LTE standard, but limits the bandwidth to a single narrow band of 200kHz. It uses OFDM modulation for downlink communications and SC-FDMA for uplink communications. NB-IoT has no duty cycle restrictions when operating on licensed spectrum and will better serve IoT applications that require more frequent communications.

[0079] Figure 1 Coverage enhancement is shown. Coverage enhancement is to provide reliable connectivity with extended coverage, and NB-IoT introduces retransmission, repetition, and power ramping schemes and CE groups during both RACH procedures and data transmission procedures. Retransmission means repeating the RA request in the absence of a RA response. Repetition means repeating the preamble to improve the detection probability at the gNB. Power ramping means increasing the transmit power level to compensate for higher path loss.

[0080] Figure 1 Coverage enhancement for NTN according to various aspects of the present disclosure is presented. A wireless communication system may include one or more base stations, one or more UEs, and a core network. In some examples, the wireless communication system may be a long term evolution (LTE) network, an advanced LTE (LTE-A) network, an LTE-A Pro network, or a new radio (NR) network. In some examples, the wireless communication system may support enhanced broadband communications, ultra-reliable (e.g., mission-critical) communications, low-latency communications, communications using low-cost and low-complexity devices, or any combination thereof.

[0081] Base stations may be dispersed throughout a geographic area to form a wireless communication system, and may be devices in different forms or with different capabilities. The base station and the UE may communicate wirelessly via one or more communication links. Each base station may provide a coverage area over which the UE and the base station may establish one or more communication links. A coverage area may be an example of a geographic area over which the base station and the UE may support signal communications according to one or more radio access technologies.

[0082] UEs may be dispersed throughout the coverage area of ​​the wireless communication system, and each UE may be stationary or mobile, or stationary and mobile at different times. UEs may be devices in different forms or with different capabilities. The UEs described herein may be able to communicate with various types of devices, such as other UEs, base stations, or network equipment (e.g., core network nodes, relay devices, integrated access and backhaul (IAB) nodes, or other network equipment).

[0083] The base station may communicate with the core network, or communicate with each other, or communicate with the core network and communicate with each other. For example, the base station may interface with the core network via one or more backhaul links (e.g., via S1, N2, N3, or other interfaces). The base station may communicate with each other directly (e.g., directly between base stations), or indirectly (e.g., via the core network), or directly and indirectly via the backhaul link (e.g., via X2, Xn, or other interfaces). In some examples, the backhaul link may be or may include one or more wireless links.

[0084] One or more of the base stations described herein may include or may be referred to by a person of ordinary skill in the art as a base transceiver station, a radio base station, an access point, a radio transceiver, a NodeB, an eNodeB (eNB), a next generation NodeB or a giga-NodeB (either of which may be referred to as a gNB), a Home NodeB, a Home eNodeB, or other suitable terminology.

[0085] UE may include or may be referred to as a mobile device, a wireless device, a remote device, a handheld device or a subscriber device, or some other suitable terminology, where a "device" may also be referred to as a unit, a station, a terminal or a client, etc. UE may also include or may be referred to as a personal electronic device, such as a cellular phone, a personal digital assistant (PDA), a tablet computer, a laptop computer, or a personal computer. In some examples, a UE may include or be referred to as a wireless local loop (WLL) station, an Internet of Things (IoT) device, an Internet of Everything (IoE) device, or a machine type communication (MTC) device, etc., which may be implemented in various objects (such as appliances or vehicles, meters, etc.).

[0086] like Figure 1 As shown, the UE described in this document may be able to communicate with various types of devices, such as other UEs that may sometimes act as repeaters, as well as base stations and network equipment (including macro eNBs or gNBs, small cell eNBs or gNBs, or relay base stations, etc.).

[0087] The UE and the base station can communicate with each other wirelessly via one or more communication links on one or more carriers. The term "carrier" may refer to a group of radio spectrum resources having a defined physical layer structure for supporting a communication link. For example, a carrier for a communication link may include a portion of a radio spectrum band (e.g., a bandwidth portion (BWP)) that operates according to one or more physical layer channels of a given radio access technology (e.g., LTE, LTE-A, LTE-A Pro, NR). Each physical layer channel may carry acquisition signaling (e.g., synchronization signals, system information), control signaling for coordinating carrier operations, user data, or other signaling. A wireless communication system may use carrier aggregation or multi-carrier operation to support communication with a UE. Depending on the carrier aggregation configuration, a UE may be configured with multiple downlink component carriers and one or more uplink component carriers. Carrier aggregation may be used with frequency division duplex (FDD) and time division duplex (TDD) component carriers.

[0088] The signal waveform transmitted on the carrier may be composed of multiple subcarriers (e.g., using multi-carrier modulation (MCM) techniques, such as orthogonal frequency division multiplexing (OFDM) or discrete Fourier transform spread OFDM (DFT-S-OFDM)). In a system using MCM technology, a resource element may be composed of a symbol period (e.g., the duration of a modulation symbol) and a subcarrier, where the symbol period and subcarrier spacing are negatively correlated. The number of bits carried by each resource element may depend on the modulation scheme (e.g., the order of the modulation scheme, the coding rate of the modulation scheme, or both). Therefore, the more resource elements a UE receives and the higher the order of the modulation scheme, the higher the data rate of the UE may be. Wireless communication resources may refer to a combination of radio spectrum resources, time resources, and spatial resources (e.g., spatial layers or beams), and the use of multiple spatial layers may further increase the data rate or data integrity of communications with the UE.

[0089] The time interval of the base station or UE can be expressed in multiples of a basic time unit, which can refer to, for example, a sampling period Ts=1 / (Δfmax·Nf) seconds, where Δfmax can represent the maximum supported subcarrier spacing, and Nf can represent the maximum supported discrete Fourier transform (DFT) size. The time interval of the communication resource can be organized according to radio frames each having a specified duration (e.g., 10 milliseconds (ms)). Each radio frame can be identified by a system frame number (SFN) (e.g., ranging from 0 to 1023).

[0090] Each frame may include multiple consecutively numbered subframes or time slots, and each subframe or time slot may have the same duration. In some examples, a frame may be divided (eg, in the time domain) into subframes, and each subframe may be further divided into multiple time slots.

[0091] Alternatively, each frame may include a variable number of time slots, and the number of time slots may depend on the subcarrier spacing. Each time slot may include multiple symbol periods (e.g., depending on the length of the cyclic prefix attached to each symbol period). In some wireless communication systems 100, the time slot may be further divided into multiple micro-time slots containing one or more symbols. Excluding the cyclic prefix, each symbol period may contain one or more (e.g., Nf) sampling periods. The duration of the symbol period may depend on the subcarrier spacing or the operating frequency band.

[0092] A subframe, a time slot, a mini-time slot, or a symbol may be the smallest scheduling unit of a wireless communication system (e.g., in the time domain) and may be referred to as a transmission time interval (TTI). In some examples, the TTI duration (e.g., the number of symbol periods in a TTI) may be variable. Additionally or alternatively, the smallest scheduling unit of the wireless communication system 100 may be dynamically selected (e.g., in a burst of a shortened TTI (sTTI)).

[0093] Physical channels may be multiplexed on a carrier according to various techniques. Physical control channels and physical data channels may be multiplexed on a downlink carrier, for example, using one or more of a time division multiplexing (TDM) technique, a frequency division multiplexing (FDM) technique, or a hybrid TDM-FDM technique. A control region (e.g., a control resource set (CORESET)) of a physical control channel may be defined by multiple symbol periods and may extend across a system bandwidth or a subset of a system bandwidth of a carrier. One or more control regions (e.g., CORESETs) may be configured for a group of UEs. For example, one or more UEs therein may monitor or search a control region to obtain control information according to one or more search space sets, and each search space set may include one or more control channel candidates of one or more aggregation levels arranged in a cascaded manner. The aggregation level of a control channel candidate may refer to the number of control channel resources (e.g., control channel elements (CCEs)) associated with the coded information of a control information format having a given payload size. A search space set may include: a common search space set configured to send control information to multiple UEs, and a UE-specific search space set for sending control information to a specific UE.

[0094] In some examples, the base station may be mobile and thus provide communication coverage for mobile geographic coverage areas. In some examples, different geographic coverage areas associated with different technologies may overlap, but the different geographic coverage areas may be supported by the same base station. In other examples, overlapping geographic coverage areas associated with different technologies may be supported by different base stations. Wireless communication systems may include, for example, heterogeneous networks in which different types of base stations provide coverage for various geographic coverage areas using the same or different radio access technologies.

[0095] The wireless communication system can be configured to support ultra-reliable communication or low-latency communication, or various combinations thereof. For example, the wireless communication system can be configured to support ultra-reliable low-latency communication (URLLC) or mission-critical communication. UE can be designed to support ultra-reliable, low-latency or critical functions (e.g., mission-critical functions). Ultra-reliable communication can include private communication or group communication, and can be supported by one or more mission-critical services (such as mission-critical push-to-talk (MCPTT), mission-critical video (MCVideo), or mission-critical data (MCData)). Support for mission-critical functions can include service prioritization, and mission-critical services can be used for public safety or general commercial applications. The terms ultra-reliable, low-latency, mission-critical, and ultra-reliable low-latency can be used interchangeably in this article.

[0096] In some examples, a UE may also be able to communicate directly with other UEs via a device-to-device (D2D) communication link (e.g., using a peer-to-peer (P2P) or D2D protocol). One or more UEs utilizing D2D communication may be within the geographic coverage area of ​​a base station. Other UEs in such a group may be outside the geographic coverage area of ​​the base station or unable to receive transmissions from the base station. In some examples, a group of UEs communicating via D2D communication may utilize a one-to-many (1:M) system in which each UE transmits to each other UE in the group. In some examples, the base station facilitates the scheduling of resources for D2D communication. In other cases, D2D communication is performed between UEs without involving a base station.

[0097] The core network may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The core network may be an evolved packet core (EPC) or a 5G core (5GC), which may include: at least one control plane entity (e.g., a mobility management entity (MME), an access and mobility management function (AMF)) for managing access and mobility, and at least one user plane entity (e.g., a serving gateway (S-GW), a packet data network (PDN) gateway (P-GW), or a user plane function (UPF)) for routing packets or interconnections to an external network. The control plane entity may manage non-access stratum (NAS) functions, such as mobility, authentication, and bearer management of UEs served by base stations associated with the core network. User IP packets may be transmitted via user plane entities, which may provide IP address allocation and other functions. The user plane entity may be connected to a network operator IP service. Operator IP services may include access to the Internet, (multiple) intranets, IP multimedia subsystems (IMS), or packet-switched streaming services.

[0098] Some network devices (such as base stations) may include subcomponents (such as access network entities, which may be examples of access node controllers (ANCs)). Each access network entity may communicate with the UE through one or more other access network transport entities, which may be referred to as radio heads, smart radio heads, or transmit / receive points (TRPs). Each access network transport entity may include one or more antenna panels. In some configurations, the various functions of each access network entity or base station may be distributed across various network devices (e.g., radio heads and ANCs), or merged into a single network device (e.g., a base station).

[0099] Wireless communication systems may operate using one or more frequency bands, typically in the range of 300 megahertz (MHz) to 300 gigahertz (GHz). Typically, the region from 300 MHz to 3 GHz is referred to as the ultra-high frequency (UHF) region or decimeter band because the length of the wavelength is in the range from about one decimeter to one meter. UHF waves may be blocked or redirected by buildings and environmental features, but for macro cells, these waves may penetrate structures sufficiently to provide service to UEs located indoors. Transmissions using UHF waves may be associated with smaller antennas and shorter ranges (e.g., less than 100 kilometers) compared to transmissions using smaller frequencies and longer waves in the high frequency (HF) or very high frequency (VHF) portions of the spectrum below 300 MHz.

[0100] Wireless communication systems can utilize both licensed radio spectrum bands and unlicensed radio spectrum bands. For example, wireless communication systems can employ licensed assisted access (LAA), LTE-unlicensed (LTE-U) radio access technology, or NR technology in unlicensed bands (such as the 5 GHz industrial, scientific, and medical (ISM) band). When operating in unlicensed radio spectrum bands, devices (such as base stations and UEs) can employ carrier sensing for collision detection and avoidance. In some examples, operations in unlicensed bands can be based on a carrier aggregation configuration (e.g., LAA) combined with component carriers operating in licensed bands. Operations in unlicensed spectrum can include downlink transmissions, uplink transmissions, P2P transmissions, or D2D transmissions, among others.

[0101] A base station or UE may be equipped with multiple antennas that may be used to employ techniques such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communications, or beamforming. The antennas of a base station or UE may be located within one or more antenna arrays or antenna panels that may support MIMO operations, or transmit or receive beamforming. For example, one or more base station antennas or antenna arrays may be co-located at an antenna assembly (such as an antenna tower). In some examples, antennas or antenna arrays associated with a base station may be located in different geographical locations. A base station may have an antenna array with multiple rows and columns of antenna ports that the base station may use to support beamforming for communications with a UE. Similarly, a UE may have one or more antenna arrays that may support various MIMO or beamforming operations. Additionally or alternatively, an antenna panel may support radio frequency beamforming for signals transmitted via an antenna port.

[0102] Beamforming (which may also be referred to as spatial filtering, directional transmission, or directional reception) is a signal processing technique that can be used at a transmitting device or a receiving device (e.g., a base station, a UE) to shape or steer an antenna beam (e.g., a transmit beam, a receive beam) along a spatial path between the transmitting device and the receiving device. Beamforming can be achieved by combining signals transmitted via antenna elements of an antenna array so that some signals propagating at a specific orientation relative to the antenna array experience constructive interference while other signals experience destructive interference.

[0103] Adjustments to signals transmitted via antenna elements may include a transmitting device or a receiving device applying an amplitude offset, a phase offset, or both an amplitude offset and a phase offset to signals carried via antenna elements associated with the device. Adjustments associated with each of the antenna elements may be defined by a set of beamforming weights associated with a particular orientation (e.g., relative to an antenna array of the transmitting device or the receiving device, or relative to some other orientation).

[0104] The wireless communication system includes a base station, a UE, a satellite, and a core network. In some examples, the wireless communication system may be an LTE network, an LTE-A network, an LTE-A Pro network, or an NR network. In some cases, the wireless communication system may support enhanced broadband communication, ultra-reliable (e.g., mission-critical) communication, low-latency communication, or communication using low-cost and low-complexity devices.

[0105] The wireless communication system may also include one or more satellites. The satellite may communicate with a base station (also referred to as a gateway in the NTN) and a UE (or other high altitude or ground communication equipment). The satellite may be any suitable type of communication satellite configured to relay communications between different end nodes in the wireless communication system. The satellite may be an example of a space satellite, a balloon, a spacecraft, an airplane, a drone, an unmanned aerial vehicle, etc. In some examples, the satellite may be in a geosynchronous or geostationary orbit, a low earth orbit, or a medium earth orbit. The satellite may be a multi-beam satellite configured to provide services for a plurality of service beam coverage areas in a predetermined geographic service area. The satellite may be at any distance from the surface of the earth.

[0106] In some cases, the cell can be provided or established by a satellite as a part of a non-terrestrial network. In some cases, the satellite can perform the function of a base station, serve as a bent-pipe satellite, or can serve as a regenerative satellite, or is a combination of the above. In other cases, the satellite can be an intelligent satellite or an example of a satellite with intelligence. For example, an intelligent satellite can be configured to perform more functions than a regenerative satellite (for example, can be configured to perform a specific algorithm outside those algorithms used in the regenerative satellite, be configured to be reprogrammed, etc.). A bent-pipe transponder or satellite can be configured to receive signals from a ground station and transmit these signals to different ground stations. In some cases, a bent-pipe transponder or satellite can amplify a signal or convert it from an uplink frequency to a downlink frequency. Like a bent-pipe transponder or satellite, a regenerative transponder or satellite can be configured to relay a signal, but airborne processing can also be used to perform other functions. The examples of these other functions can include demodulating the received signal, decoding the received signal, recoding the signal to be transmitted, or modulating the signal to be transmitted, or a combination of the above. For example, a bent-tube satellite (e.g., a satellite) can receive a signal from a base station and can relay the signal to a UE or base station, or vice versa. According to various aspects of the present disclosure, coverage enhancement of communications with satellite 120 can be provided by repeating communications, which can reduce BLER and enhance communication reliability.

[0107] The UE may include a UE communication manager. The UE communication manager may receive an indication of repeated activation of a communication from a base station or a satellite. The UE communication manager may determine resources for communications containing repetitions in response to the repetition indication. When receiving communications, the UE communication manager may buffer signals from resources containing multiple transmissions and attempt to decode associated communications. In some cases, when transmitting an uplink message to a base station or a satellite, the UE communication manager may prepare multiple repetitions of the communication based on the configured repetitions. In addition, in some cases, a frequency bandwidth smaller than the full channel bandwidth may be used to transmit the uplink message in order to provide a higher power density and enhance the likelihood of receiving the uplink message.

[0108] The base station may include a base station communication manager. The base station communication manager may configure a coverage enhancement scheme at one or more UEs, wherein multiple repetitions of communications are provided to help reduce the BLER. Repetitions may be provided by slot bundling PDCCHs in consecutive or non-consecutive time slots, or by multiple repetitions within the same time slot.

[0109] Coverage Enhancement: CE is achieved through repetition in time, retransmission, and power boost in both in-band and guard-band modes of operation. The coverage extension feature of NB-IoT comes in handy when sensors are located in remote or challenging areas. Reliable coverage enhancement is achieved through repeated transmission of data and control signaling. Each transmission can be configured to repeat a specified number of times to achieve a higher chance of success at the desired coverage level.

[0110] The repetition number value is proportional to the maximum coupling loss (MCL).

[0111] The number of repetitions will improve the SNR at the receiver. An increase in the number of repetitions leads to an increase in energy consumption. A large number of repetitions leads to a higher latency. CE will cause a waste of radio resources (UE occupies the channel for a longer duration in the case of a higher level of CE). CE is suitable for applications that are not sensitive to latency (applications that can tolerate a transmission delay of 10 seconds). Avoiding CE upgrades using any alternative can improve energy efficiency and reduce radio resource waste.

[0112] FIG2 illustrates the establishment of a successful RA.

[0113] Figure 2b RA failure and retransmission are shown.

[0114] Figure 3 A repetition of the preamble (CE) is shown.

[0115] In this Figure 2a , Figure 2b and Figure 3In , the UE behavior is: if all RA attempts fail, the UE will perform cell reselection in idle mode or report RLF in connected mode.

[0116] Figure 4 A flow chart of a prior art CE procedure is shown.

[0117] The user equipment (UE) attempts to perform a random access (RA). In the event of a failure, an upgrade to a higher CE level is performed. If no conventional radio access (RA) procedure fails, the process stops.

[0118] The core aspect of this new approach is to create a mechanism where the UE decides whether to upgrade to a higher level CE or switch networks (TN to NTN, or NTN to TN) in the event that the maximum RA procedure fails. When the UE (NB-IoT) is initially connected to the TN, it can consider utilizing the NTN before upgrading to a higher level CE (CE 1, CE 2). When the UE (NB-IoT) is initially connected to the NTN, it can consider utilizing the TN before upgrading to a higher level CE (CE 1, CE 2).

[0119] Figure 5 A flow chart of the first embodiment on the UE side is shown. A method for performing energy-saving coverage enhancement (CE) by a user equipment (UE) device connected to a wireless communication network, wherein, in the case of failure to reach the maximum random access (RA) procedure, the user equipment (UE) decides whether to upgrade to a higher level of coverage enhancement (CE) or switch networks. The user equipment (UE) is in idle mode, and the user equipment (UE) decides whether to switch to an alternative network based on overall network congestion, wherein the information is indicated by the network through the failure to reach the maximum random access (RA) procedure of the coverage enhancement (CE) level (k), and cell selection on the alternative network is performed, and the coverage of the cell is verified, and if the coverage of the cell is sufficient, the user equipment (UE) switches to the alternative network and performs a random access (RA) procedure, and if the coverage of the cell is insufficient, the user equipment (UE) remains in the same network and upgrades from the coverage enhancement (CE) level (k) to level (k+1) for the random access (RA) procedure.

[0120] The UE switches to the alternative network only when the coverage of the alternative network is good. If the coverage of the alternative network is poor, the UE will remain in the same network and upgrade the CE level.

[0121] Figure 6 A flow chart of the first embodiment on the base station (gNB) side is shown.

[0122] The method includes: receiving a random access (RA) request for coverage enhancement (CE), sending a notification to a user equipment (UE) in an idle mode state, and the user equipment (UE) deciding whether to switch to an alternative network based on overall network congestion, wherein the decision information is determined by the failure of a maximum random access (RA) procedure reaching a coverage enhancement (CE) level (k), and in the event of a failure of a maximum random access (RA) procedure reaching a coverage enhancement (CE) level (k), checking whether a user equipment (UE)-triggered switch to an alternative network should be performed, and if the result of the check is positive, performing a switch to an alternative network, and if the result of the check is negative, the user equipment (UE) remains in the same network and is upgraded from coverage enhancement (CE) level (k) to level (k+1) for the random access (RA) procedure, whereby the base station (gNB) configures the user equipment (UE) whether to switch to the alternative network.

[0123] Figure 7 The flowchart of the second embodiment on the UE side is shown. The embodiment includes the following steps: the user equipment (UE) is in a connected mode, the user equipment (UE) decides whether to switch to an alternative network based on the overall network congestion, wherein the decision information is determined by the failure of the maximum random access (RA) procedure reaching the coverage enhancement (CE) level (k), and in the case of the failure of the maximum random access (RA) procedure reaching the coverage enhancement (CE) level (k), it is checked whether the user equipment (UE) should trigger a handover to the alternative network, if the result of the check is positive, the handover to the alternative network is performed, and if the result of the check is negative, the user equipment (UE) remains in the same network and is upgraded from the coverage enhancement (CE) level (k) to the level (k+1) for the random access (RA) procedure.

[0124] Figure 8 A flow chart of the second embodiment on the gNB side is shown.

[0125] The method comprises the steps of receiving a radio access (RA) requesting coverage enhancement (CE), a notification to a user equipment (UE) in connected mode, the user equipment (UE) deciding whether to switch to an alternative network based on overall network congestion, wherein the decision information is determined by a maximum random access (RA) procedure failure reaching a coverage enhancement (CE) level (k), checking whether a user equipment (UE) triggered handover to the alternative network should be performed in the event of a maximum random access (RA) procedure failure reaching a coverage enhancement (CE) level (k). If the result of the check is positive, a handover to the alternative network is performed, if the result of the check is negative, the user equipment (UE) remains in the same network and is upgraded from coverage enhancement (CE) level (k) to level (k+1) for the random access (RA) procedure, whereby the base station (gNB) configures the user equipment (UE) whether to switch to the alternative network.

[0126] Fig. 9 A wireless communication system for performing energy-saving coverage enhancement, wherein after a user equipment (UE) obtains handover decision information from at least one cell A to at least another cell B based on defined criteria, the handover triggered by the user equipment (UE) is performed after performing the following steps:

[0127] The user equipment (UE) sends a random access (RA) request to cell A with a coverage enhancement (CE) level (k).

[0128] Cell A sends a random access (RA) failure coverage enhancement (CE) level (k) back to the user equipment (UE) and waits for the user equipment (UE) to connect with a higher coverage enhancement (CE) level (k).

[0129] The user equipment (UE) sends a random access (RA) request coverage enhancement (CE) level (k) to the cell B, and if the user equipment (UE) cannot perform random access (RA), the cell A buffers the data of the user equipment (UE).

[0130] Cell B sends a random access (RA) response coverage enhancement (CE) level (k) back to the user equipment (UE). The user equipment (UE) and cell B are connected.

[0131] Cell B updates the details of the user equipment (UE). If cell A obtains updates about the user equipment (UE) from cell B, cell A transmits the data of the user equipment (UE) to the cell. If cell A does not obtain updates about the user equipment (UE) from other cells, cell A declares a radio link failure (RLF).

[0132] The advantage of this new approach is low power consumption. NB-IoT and LTE-M chipsets focus on the radio characteristics required by the application and have energy-saving features such as sleep mode, long-cycle tracking area updates and extended discontinuous reception, which ensures optimal energy efficiency.

[0133] In addition, deep building penetration can be achieved. Compared to GSM to narrowband modulation and multiple transmission repetitions, NB-IoT and LTE-M have higher power density of up to 20 dB (NB-IoT) and 15 dB (LTE-M). This ensures better network coverage inside buildings.

[0134] A very important aspect of this new approach is low cost. Both LTE-M and NB-IoT have the advantage of low module costs and low operating and service prices. This is ensured by a simple chipset design (which leaves out unnecessary LTE functions) and increased production volumes.

[0135] All described solutions are based on LTE. NB-IoT and LTE-M are based on LTE and can be integrated into existing LTE infrastructure via software upgrades. Since both NB-IoT and LTE-M can be provided in GSM and LTE spectrum, no additional spectrum authorization is required.

[0136] Unlike sensors that cannot transmit over long distances, both NB-IoT and LTE-M work via plug-and-play. Sensors connect directly to the NB-IoT and / or LTE-M network without the need to install a local network or gateway.

[0137] Another very interesting aspect of the described solutions is that they are extremely secure. NB-IoT and LTE-M are globally standardized technologies and use the LTE security mechanisms according to 3GPP.

[0138] abbreviation:

[0139] Discontinuous Reception DRX Extended Discontinuous Reception gNB: gNodeB eDRX Internet of Things IoT Low Power Wide Area Network LPWAN Narrowband Internet of Things NB-IoT Release auxiliary indicator RAI Random Access RA Random Access Channel RACH User Equipment UE Wake-up signal Wlq

Claims

1. A method for performing energy-saving coverage enhancement (CE) by a user equipment (UE) device connected to a wireless communication network, wherein: In case of failure to reach the maximum random access (RA) procedure, the user equipment (UE) decides whether to upgrade to a higher level of coverage enhancement (CE) or to handover the network.

2. The method for energy-saving coverage enhancement (CE) according to claim 1, comprising the steps followed by the user equipment (UE) when it is in idle mode: the user equipment (UE) decides whether to switch to an alternative network based on the overall network congestion, wherein, This information is indicated by the network through a maximum random access (RA) procedure failure to reach coverage enhancement (CE) level (k), and the user equipment (UE) then performs cell selection on an alternative network, wherein the coverage of the cell is verified, and in case the coverage of the cell is sufficient the user equipment (UE) switches to the alternative network and performs a random access (RA) procedure, in case the coverage of the cell is insufficient the user equipment (UE) remains in the same network and is upgraded from the level (k) to coverage enhancement (CE) level (k+1) for the random access (RA) procedure.

3. The method for Energy Saving Coverage Enhancement (CE) according to claim 1, comprising steps followed by the user equipment (UE) when it is in connected mode: the user equipment (UE) decides whether to switch to an alternative network based on overall network congestion, wherein, The decision information is determined by the failure of the maximum random access (RA) procedure reaching the coverage enhancement (CE) level (k), and in the case of the failure of the maximum random access (RA) procedure reaching the coverage enhancement (CE) level (k), checking whether the user equipment (UE) should trigger a handover to an alternative network, if the result of the check is positive, then the handover to the alternative network is performed, if the result of the check is negative, then the user equipment (UE) remains in the same network and is upgraded from the level (k) to the coverage enhancement (CE) level (k+1) for the random access (RA) procedure.

4. The method for energy-saving coverage enhancement (CE) according to claims 1 to 3, wherein: In case of failure to reach the maximum random access (RA) procedure, the network switches from a terrestrial network to a non-terrestrial network (TN to NTN) or from a non-terrestrial network to a terrestrial network (NTN to TN).

5. The method according to claims 1 to 4, wherein: The user equipment (UE) is a user equipment for narrowband Internet of Things UE (NB-IoT), and when the user equipment is initially connected to a terrestrial network (TN), it considers utilizing a non-terrestrial network (NTN) instead of the terrestrial network (TN) before upgrading to a higher level of coverage enhancement (CE, CE 1, CE 2).

6. The method according to claims 1 to 5, wherein: The user equipment (UE) is a user equipment for narrowband Internet of Things UE (NB-IoT), and when the user equipment is initially connected to a non-terrestrial network instead of a terrestrial network (NTN), it considers utilizing a terrestrial network (TN) before upgrading to a higher level of coverage enhancement (CE, CE 1, CE 2).

7. The method according to claim 1 or 6, wherein: The method is characterized in that when the user equipment (UE) reaches a maximum random access (RA) procedure failure, the user equipment (UE) has the opportunity to switch the network instead of upgrading the coverage enhancement (CE) level, thereby reducing signaling overhead and / or power consumption of the user equipment UE.

8. A method for performing energy-saving coverage enhancement (CE) by a base station (gNB) in a wireless communication network, wherein: The method includes: receiving a random access (RA) request for coverage enhancement (CE), sending a notification to a user equipment (UE) in an idle mode state, and The user equipment (UE) decides whether to switch to an alternative network based on the overall network congestion, wherein the decision information is determined by a maximum random access (RA) procedure failure to reach a coverage enhancement (CE) level (k), In case of failure to reach the maximum random access (RA) procedure for coverage enhancement (CE) level (k), checking whether a handover to an alternative network triggered by the user equipment (UE) should be performed, If the result of this check is positive, the switch to the alternative network is performed, If the result of this check is negative, the user equipment (UE) remains in the same network and is upgraded from the current level (k) to the coverage enhancement (CE) level (k+1) for the random access (RA) procedure, whereby the base station (gNB) configures the user equipment (UE) whether to switch to an alternative network.

9. A method for performing energy-saving coverage enhancement (CE) by a base station (gNB) in a wireless communication network, wherein: The method includes: receiving a random access (RA) requesting a coverage enhancement (CE), notification from a user equipment (UE) in connected mode, The user equipment (UE) decides whether to switch to an alternative network based on the overall network congestion, wherein the decision information is determined by the failure of the maximum random access (RA) procedure reaching the coverage enhancement (CE) level (k), and in the case of the failure of the maximum random access (RA) procedure reaching the coverage enhancement (CE) level (k), it is checked whether the user equipment (UE) should trigger the switch to the alternative network, if the result of the check is positive, the switch to the alternative network is performed, if the result of the check is negative, the user equipment (UE) remains in the same network and is upgraded from the current level (k) to the coverage enhancement (CE) level (k+1) for the random access (RA) procedure, thereby the base station (gNB) configures the user equipment (UE) whether to switch to the alternative network.

10. An apparatus for receiving a transmission for energy-saving coverage enhancement (CE) from a user equipment (UE) in a wireless communication network, the apparatus comprising a wireless transceiver, a processor coupled to a memory having computer program instructions stored therein, the instructions being configured to implement the steps of the method of claims 1 to 7.

11. An apparatus for receiving a transmission for energy-saving coverage enhancement (CE) from a base station (gnB) in a wireless communication network, the apparatus comprising a wireless transceiver, a processor (602) coupled to a memory having computer program instructions stored therein, the instructions being configured to implement the steps of the method of claims 8 to 9.

12. A user equipment comprising the apparatus according to claim 10.

13. A base station comprising the device according to claim 11.

14. A wireless communication system for performing energy-saving coverage enhancement from a base station to a user equipment, wherein: The base station comprises a processor coupled to a memory having computer program instructions stored therein, the instructions being configured to implement the steps of the method of claims 8 to 9; Therein, the user equipment (UE) comprises a processor coupled to a memory having computer program instructions stored therein, the instructions being configured to implement the steps of the method of claims 1 to 7.

15. The wireless communication system for performing energy-saving coverage enhancement according to claim 14, wherein: After a user equipment (UE) obtains handover decision information from at least one cell A to at least another cell B based on defined criteria, a handover triggered by the user equipment (UE) is performed after performing the following steps: a.) The user equipment (UE) sends a random access (RA) request to cell A with a coverage enhancement (CE) level (k), b.) In case of RA failure at CE level (k), cell A waits for UE to connect with higher CE level (k), c.) The user equipment (UE) sends a random access (RA) request to the cell B with a coverage enhancement (CE) level (k), and if the user equipment (UE) cannot perform radio access (RA), the cell A buffers the data of the user equipment (UE), d.) Cell B sends a random access (RA) response coverage enhancement (CE) level (k) back to the user equipment (UE), e.) User equipment (UE) is connected to cell B, f.) Cell B updates the details of the user equipment (UE) via the X2 interface. If cell A obtains updates about the user equipment (UE) from cell B, cell A transmits the data of the user equipment (UE) to cell B. g) If cell A does not get updates about the user equipment (UE) from other cells, cell A declares a radio link failure (RLF).

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