Grouping of time alignment errors at multiple transmitting and receiving points

Abstract

A method is disclosed that includes determining to receive a configuration from a network entity indicating a group comprising transmission / reception points (TRPs) having an realized timing alignment error capped at a threshold; having a first connection to a first TRP of the group; obtaining a first timing advance value for an uplink to the first TRP; determining to establish a second connection to a second TRP; determining whether the second TRP is in the group based on the received configuration; measuring a reception time difference between the first TRP and the second TRP in response to the second TRP being in the group; and determining a second timing advance value for an uplink to the second TRP based on the obtained first timing advance value and the measured reception time difference.

Description

[Technical Field]

[0001] The following exemplary embodiments relate to wireless communications and time alignment errors for multiple transmitting and receiving points in a wireless communications network. [Background technology]

[0002] A cellular communication network may comprise multiple transmission-reception points (TRPs), and simultaneous signal transmission from two or more different transmission-reception points (TRPs) may be subject to timing alignment error (TAE) between the two or more TRPs.

[0003] The scope of protection sought for various embodiments of the invention is defined by the independent claims. To the extent that some exemplary embodiments and features described herein do not fall within the scope of the independent claims, they should be interpreted as examples that serve to understand various embodiments of the invention. Summary of the Invention

[0004] According to a first aspect, there is provided an apparatus comprising means for receiving from a network entity a configuration indicating a group of transmission and reception points having an achieved timing alignment error capped by a threshold value; establishing a first connection to a first transmission and reception point comprised in the group; receiving a first timing advance value for uplink transmission to the first transmission and reception point; determining that a second connection to a second transmission and reception point will be established; determining based on the received configuration whether a second transmission and reception point is comprised in the group; measuring a reception time difference between the first transmission and reception point and the second transmission and reception point in response to the second transmission and reception point being comprised in the group; and determining a second timing advance value for uplink transmission to the second transmission and reception point based on the obtained first timing advance value and the measured reception time difference.

[0005] In some exemplary embodiments according to the first aspect, the means comprises at least one processor and at least one memory that stores instructions that, when executed by the at least one processor, cause performance of the apparatus.

[0006] According to a second aspect, there is provided an apparatus comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to at least perform the following: receive, from a network entity, a configuration indicating a group of transmitting and receiving points having an achieved timing alignment error capped by a threshold; establish a first connection to a first transmitting and receiving point comprised in the group; receive a first timing advance value for uplink transmission to the first transmitting and receiving point; determine that a second connection to a second transmitting and receiving point will be established; determine based on the received configuration whether a second transmitting and receiving point is comprised in the group; measure a reception time difference between the first transmitting and receiving point and the second transmitting and receiving point in response to the second transmitting and receiving point being comprised in the group; and determine a second timing advance value for uplink transmission to the second transmitting and receiving point based on the received first timing advance value and the measured reception time difference.

[0007] According to a third aspect, there is provided a method comprising: receiving, from a network entity, a configuration indicating a group of transmission and reception points having an achieved timing alignment error capped by a threshold; establishing a first connection to a first transmission and reception point comprised in the group; receiving a first timing advance value for uplink transmission to the first transmission and reception point; determining that a second connection to a second transmission and reception point will be established; determining based on the received configuration whether a second transmission and reception point is comprised in the group; measuring a reception time difference between the first transmission and reception point and the second transmission and reception point in response to the second transmission and reception point being comprised in the group; and determining a second timing advance value for uplink transmission to the second transmission and reception point based on the received first timing advance value and the measured reception time difference.

[0008] In some exemplary embodiments according to the third aspect, the method is a computer-implemented method.

[0009] According to a fourth aspect, there is provided a computer program comprising instructions that, when executed by an apparatus, cause the apparatus to at least: receive from a network entity a configuration indicating a group of transmission and reception points having an achieved timing alignment error capped by a threshold; establish a first connection to a first transmission and reception point comprised in the group; receive a first timing advance value for uplink transmission to the first transmission and reception point; determine that a second connection to a second transmission and reception point will be established; determine based on the received configuration whether a second transmission and reception point is comprised in the group; measure a reception time difference between the first transmission and reception point and the second transmission and reception point in response to the second transmission and reception point being comprised in the group; and determine a second timing advance value for uplink transmission to the second transmission and reception point based on the received first timing advance value and the measured reception time difference.

[0010] According to a fifth aspect, there is provided a computer program comprising instructions for at least receiving from a network entity a configuration indicating a group of transmission and reception points having an achieved timing alignment error capped by a threshold; establishing a first connection to a first transmission and reception point comprised in the group; receiving a first timing advance value for uplink transmission to the first transmission and reception point; determining that a second connection to a second transmission and reception point will be established; determining based on the received configuration whether a second transmission and reception point is comprised in the group; measuring a reception time difference between the first transmission and reception point and the second transmission and reception point in response to the second transmission and reception point being comprised in the group; and determining a second timing advance value for uplink transmission to the second transmission and reception point based on the received first timing advance value and the measured reception time difference.

[0011] According to a sixth aspect, there is provided a non-transitory computer-readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to at least: receive from a network entity a configuration indicating a group of transmission and reception points having an achieved timing alignment error capped by a threshold; establish a first connection to a first transmission and reception point comprised in the group; receive a first timing advance value for uplink transmission to the first transmission and reception point; determine that a second connection to a second transmission and reception point will be established; determine based on the received configuration whether a second transmission and reception point is comprised in the group; measure a reception time difference between the first transmission and reception point and the second transmission and reception point in response to the second transmission and reception point being comprised in the group; and determine a second timing advance value for uplink transmission to the second transmission and reception point based on the received first timing advance value and the measured reception time difference.

[0012] According to a seventh aspect, there is provided a non-transitory computer-readable medium having stored thereon program instructions to at least perform the following: receiving from a network entity a configuration indicating a group of transmission and reception points having an achieved timing alignment error capped by a threshold; establishing a first connection to a first transmission and reception point comprised in the group; receiving a first timing advance value for uplink transmission to the first transmission and reception point; determining that a second connection to a second transmission and reception point will be established; determining based on the received configuration whether a second transmission and reception point is comprised in the group; measuring a reception time difference between the first transmission and reception point and the second transmission and reception point in response to the second transmission and reception point being comprised in the group; and determining a second timing advance value for uplink transmission to the second transmission and reception point based on the received first timing advance value and the measured reception time difference.

[0013] According to an eighth aspect, there is provided a computer-readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to at least: receive from a network entity a configuration indicating a group of transmission and reception points having an achieved timing alignment error capped by a threshold; establish a first connection to a first transmission and reception point comprised in the group; receive a first timing advance value for uplink transmission to the first transmission and reception point; determine that a second connection to a second transmission and reception point will be established; determine based on the received configuration whether a second transmission and reception point is comprised in the group; measure a reception time difference between the first transmission and reception point and the second transmission and reception point in response to the second transmission and reception point being comprised in the group; and determine a second timing advance value for uplink transmission to the second transmission and reception point based on the received first timing advance value and the measured reception time difference.

[0014] According to a ninth aspect, there is provided a computer-readable medium having stored thereon program instructions to at least perform the following: receiving from a network entity a configuration indicating a group of transmission and reception points having an achieved timing alignment error capped by a threshold; establishing a first connection to a first transmission and reception point comprised in the group; receiving a first timing advance value for uplink transmission to the first transmission and reception point; determining that a second connection to a second transmission and reception point will be established; determining based on the received configuration whether a second transmission and reception point is comprised in the group; measuring a reception time difference between the first transmission and reception point and the second transmission and reception point in response to the second transmission and reception point being comprised in the group; and determining a second timing advance value for uplink transmission to the second transmission and reception point based on the received first timing advance value and the measured reception time difference.

[0015] According to a tenth aspect, there is provided an apparatus comprising: means for determining a group of transmitting and receiving points having an achieved timing alignment error capped by a threshold; and means for transmitting a configuration indicating the group to a terminal device.

[0016] In some exemplary embodiments according to the tenth aspect, the means comprises at least one processor and at least one memory that stores instructions that, when executed by the at least one processor, cause performance of the apparatus.

[0017] According to an eleventh aspect, there is provided an apparatus comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to at least determine a group of transmitting and receiving points having an achieved timing alignment error, upper bounded by a threshold, and send a configuration indicating the group to a terminal device.

[0018] According to a twelfth aspect, there is provided a method comprising determining a group of transmitting and receiving points having an achieved timing alignment error capped by a threshold value, and transmitting a configuration indicating the group to a terminal device.

[0019] In certain exemplary embodiments according to the twelfth aspect, the method is a computer-implemented method.

[0020] According to a thirteenth aspect, there is provided a computer program comprising instructions that, when executed by an apparatus, cause the apparatus to at least determine a group of transmitting and receiving points having an achieved timing alignment error capped by a threshold value, and send a configuration indicating the group to a terminal device.

[0021] According to a fourteenth aspect, there is provided a computer program having stored thereon instructions for at least determining a group of transmitting and receiving points having an achieved timing alignment error capped by a threshold value, and transmitting a configuration indicating the group to a terminal device.

[0022] According to a fifteenth aspect, there is provided a non-transitory computer-readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to at least determine a group of transmitting and receiving points having an achieved timing alignment error capped by a threshold value, and send a configuration indicating the group to a terminal device.

[0023] According to a sixteenth aspect, there is provided a non-transitory computer-readable medium having stored thereon program instructions for at least determining a group of transmitting and receiving points having an achieved timing alignment error capped by a threshold value, and transmitting a configuration indicating the group to a terminal device.

[0024] According to a seventeenth aspect, there is provided a computer-readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to at least determine a group of transmitting and receiving points having an achieved timing alignment error capped by a threshold value, and send a configuration indicating the group to a terminal device.

[0025] According to an eighteenth aspect, there is provided a computer-readable medium having stored thereon program instructions for at least determining a group of transmitting and receiving points having an achieved timing alignment error capped by a threshold value, and transmitting a configuration indicating the group to a terminal device.

[0026] In the following, the invention will be explained in more detail with reference to embodiments and the accompanying drawings. [Brief explanation of the drawings]

[0027] [Figure 1] FIG. 1 illustrates an exemplary embodiment of a radio access network. [Figure 2]FIG. 1 illustrates an exemplary embodiment of a network topology. [Figure 3] FIG. 1 illustrates an exemplary embodiment of timing for a terminal device to transmit and receive signals using multiple transmission and reception points. [Figure 4] FIG. 1 illustrates an example embodiment in which there is an implemented time alignment error that is unknown to the terminal device. [Figure 5A] FIG. 1 illustrates an exemplary embodiment in which a terminal device connects to multiple transmission and reception points. [Figure 5B] FIG. 1 illustrates an exemplary embodiment in which a terminal device connects to multiple transmission and reception points. [Figure 6] FIG. 1 illustrates a signaling chart according to an exemplary embodiment. [Figure 7] FIG. 1 illustrates a flowchart in accordance with an exemplary embodiment. [Figure 8] 1A-1C illustrate time alignment errors in various exemplary scenarios. [Figure 9] FIG. 1 illustrates an exemplary embodiment of an apparatus. [Figure 10] FIG. 1 illustrates an exemplary embodiment of an apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0028] The following embodiments are illustrative. Although the specification may refer to "an," "one," or "some" embodiments in several places throughout the text, this does not necessarily mean that each reference is to the same embodiment or that a particular feature applies only to a single embodiment. Single features of different embodiments may be combined to provide other embodiments.

[0029] The term "circuit" as used in this application refers to all of the following: (a) a hardware-only circuit implementation, such as an implementation in analog and / or digital circuitry only; (b) a combination of circuitry and software (and / or firmware), such as (where applicable): (i) a combination of a processor, or (ii) a processor / software portion including a digital signal processor, software, and memory that work together to cause a device to perform various functions; and (c) a circuit that requires software or firmware to operate, even if the software or firmware is not physically present, such as a microprocessor or portion of a microprocessor. This definition of "circuit" applies to all uses of the term in this application. As a further example, the term "circuit" as used in this application also covers an implementation of simply a processor (or processors) or portion of a processor and its (or their) accompanying software and / or firmware. The term "circuit" also covers, for example, a baseband integrated circuit or an application processor integrated circuit for a mobile phone, or a similar integrated circuit in a server, cellular network device, or other network device, if applicable to the particular element. The circuit embodiments described above may be considered as embodiments that provide means for performing method or process embodiments described herein.

[0030] The techniques and methods described herein may be implemented by various means. For example, these techniques may be implemented in hardware (one or more devices), firmware (one or more devices), software (one or more modules), or a combination thereof. In a hardware implementation, an apparatus of an embodiment may be implemented within one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), graphics processing units (GPUs), processors, controllers, microcontrollers, microprocessors, other electronic units designed to perform the functions described herein, or a combination thereof. In the case of firmware or software, the implementation may be performed through modules (e.g., procedures, functions, etc.) of at least one chipset that perform the functions described herein. Software codes may be stored in a memory unit and executed by a processor. The memory unit may be implemented within or external to the processor. In the latter case, it may be communicatively coupled to the processor via any suitable means. Furthermore, the components of the systems described herein may be rearranged and / or supplemented by additional components to facilitate accomplishment of various aspects described therewith, etc., and are not limited to the precise configurations depicted in the given drawings, as will be understood by those skilled in the art.

[0031] The embodiments described herein may be implemented in communication systems such as at least one of the following: Global System for Mobile Communications (GSM) or any other second-generation cellular communication system; Universal Mobile Telecommunication System (UMTS, 3G) based on basic wideband-code division multiple access (W-CDMA); high-speed packet access (HSPA); Long Term Evolution (LTE); LTE-Advanced; systems based on the IEEE 802.11 specification; systems based on the IEEE 802.15 specification; and / or fifth-generation (5G) and 5G-Advanced (i.e., 3GPP NR Rel-18 and later) mobile or cellular communication systems. The embodiments described herein may also be implemented in 6G communication systems as well. However, the embodiments are not limited to the systems given as examples, and those skilled in the art may apply the solutions to other communication systems having the required characteristics.

[0032] Figure 1 shows an example of a simplified system architecture showing several elements and functional entities, all of which are logical units, the implementation of which may differ from those shown. The connections shown in Figure 1 are logical connections, and the actual physical connections may differ. It will be apparent to those skilled in the art that the system may have functions and structures other than those shown in Figure 1. The example of Figure 1 shows a portion of an exemplary radio access network.

[0033] FIG. 1 illustrates terminal devices 100 and 102 configured to be wirelessly connected over one or more communication channels within an access node (e.g., NodeB) 104 that provides a cell. The access node 104 may also be referred to as a node, network node, network device, gNB, gNodeB, NB, NodeB, or base station. The wireless link from the terminal device to the NodeB (e.g.,) is referred to as an uplink or reverse link, and the wireless link from the NodeB (e.g.,) to the terminal device is referred to as a downlink or forward link. It should be understood that a NodeB (e.g.,) or their functionality may be implemented using any node, host, server, access point, or other entity suitable for such use. It should be noted that, while this exemplary embodiment discusses one cell for ease of explanation, multiple cells may be provided by one access node in some exemplary embodiments.

[0034] A communication system may comprise multiple (for example) NodeBs, in which case the (for example) NodeBs may also be configured to communicate with each other via wired or wireless links designed for that purpose. These links may be used for signaling purposes. A (for example) NodeB is a computing device configured to control radio resources of the communication system coupled to it. A (for example) NodeB may also be referred to as a base station, an access point, or any other type of interfacing device, including a relay station operable in a wireless environment. A (for example) NodeB includes or is connected to a transceiver. The (for example) NodeB's transceiver provides a connection to an antenna unit that establishes a bidirectional radio link to a user device. The antenna unit may comprise multiple antennas or antenna elements. The (for example) NodeB is further connected to a core network 110 (CN or Next Generation Core NGC). Depending on the deployed technology, the counterparts on the CN side could be a serving gateway (S-GW, routing and forwarding of user data packets) or user plane function (UPF) for providing connectivity of terminal devices (UE) to external packet data networks, and a mobile management entity (MME) or access and mobility function (AMF) for controlling the access and mobility of terminal devices.

[0035] A terminal device represents one type of device to which resources over the air interface are allocated and assigned, and therefore, any feature described herein with respect to a terminal device may be implemented by a corresponding device, such as a relay node. One example of such a relay node is a Layer 3 relay (self-backhaul relay) toward a base station. Another example of such a relay node is a Layer 2 relay. Such a relay node may include a terminal device portion and a distributed unit (DU) portion. A centralized unit (CU) may coordinate the operation of the DUs, for example, via an F1AP interface.

[0036] A terminal device may also be referred to as user equipment (UE), subscriber device, subscriber station (SS), portable subscriber station, mobile station (MS), or access terminal (AT). A terminal device may refer to a wireless mobile communication device that operates with or without a subscriber identification module (SIM) or a portable computing device that includes an embedded SIM or eSIM, including, but not limited to, mobile stations (mobile phones), smartphones, personal digital assistants (PDAs), handsets, devices that use wireless modems (such as alarms or measurement devices), laptops and / or touchscreen computers, tablets, game consoles, notebooks, and multimedia devices. It should be understood that a user device may also be an exclusively or nearly exclusively uplink-only device, an example of which is a camera or camcorder that loads images or video clips onto the network. The terminal device may also be a device capable of operating in an Internet of Things (IoT) network, a scenario in which objects are provided with the ability to transfer data over a network without the need for human-to-human or human-to-computer interaction. The terminal device may also utilize the cloud. In some applications, the terminal device may comprise a small portable device with wireless components (such as a watch, earphones, or glasses), and computations are performed in the cloud. The terminal device (or, in some embodiments, a Layer 3 relay node) is configured to perform one or more of the user equipment functions.

[0037] The various techniques described herein may also be applied to cyber-physical systems (CPSs), which are systems consisting of cooperative computational elements that control physical entities. CPSs may enable the implementation and utilization of vast numbers of interconnected ICT devices (sensors, actuators, processors, microcontrollers, etc.) embedded in physical objects in various locations. Mobile cyber-physical systems are a subcategory of cyber-physical systems due to the inherent mobility of the physical systems in question. Examples of mobile physical systems include mobile robots and electronic devices transported by humans or animals.

[0038] Furthermore, although the device is shown as a single entity, it may be implemented with different units, processors and / or memory units (not all of which are shown in FIG. 1).

[0039] 5G enables the use of multiple input-multiple output (MIMO) antennas, many more base stations or nodes than LTE (the so-called small cell concept), and even macro sites that operate in conjunction with smaller stations and employ various radio technologies depending on service needs, use cases, and / or available spectrum. 5G mobile communications will support a wide range of use cases and related applications, including video streaming, augmented reality, various data sharing methods, and various forms of machine-type applications such as (massive) machine-type communication (mMTC), including vehicle safety, various sensors, and real-time control. 5G is expected to have multiple air interfaces, namely sub-6 GHz, cmWave, and mmWave, and to be integrable with existing conventional radio access technologies such as LTE. At least initially, integration with LTE may be implemented as a system in which macro coverage is provided by LTE and 5G air interface access is provided by small cells through aggregation to LTE. In other words, 5G is expected to support both inter-RAT interoperability (e.g., LTE-5G) and inter-RI interoperability (inter-air interface interoperability, sub-6 GHz-cmWave, sub-6 GHz-cmWave-mmWave, etc.). One of the concepts being considered for use in 5G networks is network slicing, where multiple independent and dedicated virtual sub-networks (network instances) can be created within the same infrastructure to run services with different requirements regarding latency, reliability, throughput, and mobility.

[0040] The current architecture of LTE networks is fully distributed in the radio and fully centralized in the core network. Low-latency applications and services in 5G may require content to be closer to the radio, potentially leading to local breakout and multi-access edge computing (MEC). 5G enables analytics and knowledge generation at the source of data. This approach requires leveraging resources that may not be continuously connected to the network, such as laptops, smartphones, tablets, and sensors. MEC provides a distributed computing environment for hosting applications and services. It also has the ability to store and process content closer to cellular subscribers for faster response times. Edge computing covers a wide range of technologies, including wireless sensor networks, mobile data acquisition, mobile signature analysis, cooperative distributed peer-to-peer ad-hoc networking and processing (which can also be categorized as local cloud / fog computing and grid / mesh computing), dew computing, mobile edge computing, cloudlets, distributed data storage and retrieval, autonomous self-healing networks, remote cloud services, augmented and virtual reality, data caching, Internet of Things (where large-scale connectivity and / or latency are critical), and critical communications (autonomous vehicles, road safety, real-time analytics, time-critical control, healthcare applications).

[0041] The communications system may also communicate with and / or utilize services provided by other networks, such as the public switched telephone network or the Internet 112. The communications network may also support the use of cloud services; for example, at least some of the core network operations may be performed as cloud services (this is illustrated in FIG. 1 by "cloud" 114). The communications system may also comprise a central control entity or the like that provides functionality for networks of different operators to cooperate, for example in spectrum sharing.

[0042] Edge cloud can be introduced in radio access networks (RANs) by utilizing network function virtualization (NFV) and software defined networking (SDN). The use of edge cloud may mean that access node operations are performed at least in part on a server, host, or node operatively coupled to a remote radio head or base station comprising the radio components. It is also possible for node operations to be distributed across multiple servers, nodes, or hosts. The application of cloudRAN architecture allows RAN real-time functions to be performed on the RAN side (in distributed units, DUs 104) and non-real-time functions to be performed centrally (in centralized units, CUs 108).

[0043] It should also be understood that the distribution of functions between core network operations and base station operations may differ from LTE and may even not exist in some cases. Some other technologies that may be used include, for example, big data and all-IP, which may change the way networks are built and managed. 5G (or new radio, NR) networks are designed to support multiple hierarchies, and MEC servers may be located between the core and base stations or NodeBs (gNBs). It should be understood that MEC is also applicable to 4G networks.

[0044] 5G may also utilize satellite communications to enhance or complement 5G service coverage, for example, by providing backhaul or service availability in areas without terrestrial coverage. Satellite communications may utilize geostationary earth orbit (GEO) satellite systems as well as low earth orbit (LEO) satellite systems, such as megaconstellations. Satellites 106 included in the constellation may carry gNBs, or at least portions of gNBs, that create ground cells. Alternatively, the satellites 106 may be used to relay signals of one or more cells to Earth. The ground cells may be created through terrestrial relay nodes 104 or by gNBs located on the ground or in the satellite, and some of the gNBs, such as DUs, may be on the satellite and some of the gNBs, such as CUs, may be on the ground. Additionally or alternatively, high-altitude platform station (HAPS) systems may be utilized.

[0045] It should be noted that the illustrated system is an example of a portion of a wireless access system, and the system may include multiple (e.g.,) NodeBs, a terminal device may access multiple wireless cells, and the system may also include other devices such as physical layer relay nodes or other network elements. At least one of the (e.g.,) NodeBs may be a Home (e.g.,) NodeB. Furthermore, a geographic area of ​​a wireless communication system may be provided with multiple different types of wireless cells, as well as multiple wireless cells. A wireless cell may be a macrocell (or umbrella cell), which is a large cell typically reaching tens of kilometers in diameter, or a smaller cell such as a microcell, femtocell, or picocell. The (e.g.,) NodeB in FIG. 1 may provide any of these cell types. A cellular wireless system may be implemented as a multi-tier network including multiple types of cells. In some exemplary embodiments, in a multi-tier network, one access node provides one type of cell or multiple cells, and therefore multiple (e.g.,) NodeBs are required to provide such a network structure.

[0046] When a network includes multiple TRPs, a timing alignment error (TAE) may occur between any pair of two TRPs. The TAE may be understood as the relative difference in transmission timing between two pairs of TRPs (transmission timing may be defined relative to a symbol / slot / subframe / frame boundary). The maximum value of the TAE may be determined for the network; for example, 3GPP specifications may be used to determine a predetermined value to which the maximum TAE between any pair of TRPs must conform. In other words, the TAE of a TRP pair must be less than or equal to a predetermined maximum value. This maximum value may also be understood as a TAE requirement. The actual TAE, i.e., the achieved TAE, may depend on how far the TRPs are from each other. Therefore, the achieved TAE may be much smaller than the predetermined maximum value. Figure 2 illustrates exemplary embodiments of various network topologies and synchronization of TRPs within those topologies. Figure 2 illustrates two exemplary scenarios 200 and 205. In this exemplary embodiment, two distinct synchronization points 210 and 215 exist. In this exemplary embodiment, the relative time precision between synchronization points 210 and 215 is 1000 ns. In scenario 200 and scenario 205, synchronization point 210 is connected to TRP 220 and TRP 222, and synchronization point 215 is connected to TRP 224 and TRP 226. Both synchronization points 210 and 215 are connected to their respective TRPs with a relative time precision of 300 ns. In exemplary scenario 205, TRP 222 is further connected to TRP 228 with a timing precision of 300 ns. As a result, the timing precision between TRP 220 and TRP 228 is improved, for example, to a maximum of 500 ns. The TAE between TRPs 220, 222, 224, and 226 for scenario 200 is shown in table 230. The TAE between TRPs 220, 222, 224, 226, and 228 for scenario 205 is shown in table 235.Although both network topologies in exemplary scenarios 200 and 205 meet the same TAE requirement, e.g., a maximum TAE value of 3000 ns, the realized TAE between any two of TRPs 220, 222, 224, 226, and 228 is different. The realized TAE may be deployment-specific and may also depend on the network implementation. Furthermore, the terminal device is unaware of the realized TAE between any two TRPs.

[0047] 3 illustrates an example embodiment of the timing of a terminal device 340 connected to a TRP 350 and a TRP 355, sending uplink (UL) transmissions to both TRPs 350 and 355 and receiving downlink (DL) transmissions from both TRPs 350 and 355. Propagation delay 342 is the propagation delay applied between terminal device 340 and TRP 350. Propagation delay 344 is the propagation delay applied between terminal device 340 and TRP 355.

[0048] In this exemplary embodiment, timing aspects of both DL and UL transmissions are shown. Section 360 shows transmission of DL signals by TRPs 350 and 355 to terminal device 340. DL transmission 305 from TRP 355 is delayed by TAE 370 relative to DL transmission 300 from TRP 350.

[0049] Section 362 illustrates reception of DL signals transmitted by TRPs 350 and 355 by terminal device 340. DL transmission 300 is received at terminal device 340 as DL reception 310, and DL transmission 305 is received at terminal device 340 as DL reception 315. DL reception 310 occurs after a propagation delay 342 relative to DL transmission 300. DL reception 315 occurs after a propagation delay 344 relative to DL transmission 305. From the perspective of the terminal device, there is a receive time difference (RTD) 372 between DL receptions 310 and 315. RTD 372 may be estimated by terminal device 340 based on DL reference signals (RS) received from TRPs 350 and 355, such as a synchronization signal block (SSB), a channel state information-reference signal (CSI-RS), or a phase tracking-reference signal (PT-RS).

[0050] Section 364 shows the UL transmission 320 that the terminal device 340 sends to the TRP 350 and the UL transmission 325 that the terminal device 340 sends to the TRP 355. In this exemplary embodiment, it is assumed that the terminal device 340 has already obtained the correct timing advance (TA) value for uplink transmissions to the TRPs 350 and 355. The TA value for the TRP 350 is TA 374, which is 2 * The propagation delay is equal to 342, and the TA value of TRP355 is TA376, which is 2 * The timing advance values ​​used by the terminal device 340 for the TRPs 350 and 355 are defined with respect to the DL reception 310 and 315, respectively.

[0051] Section 366 shows UL receive 330 by TRP 350 of UL transmit 320 and UL receive 335 by TRP 355 of UL transmit 325. Receive 330 is aligned with transmit 300 on both the left and right edges, and receive 335 is aligned with transmit 305 on both the left and right edges with the correct timing advance values ​​374 and 376, respectively.

[0052] As can be seen from Figure 3, TA376 of TRP355 is equal to the following equation: TA376=TA374+2*RTD372-2*Realized(TA370)

[0053] In the case of ideal synchronization between TRPs 350 and 355, i.e., when the realized TAE=0, the terminal device 340 can correctly estimate the TA 376 based on the TA 374 and the observed RTD 372. However, in practical deployments, neither an access node, such as a gNB with at least one TRP, can derive the TA 376 from the TA 374 because the access node does not know the RTD, nor the terminal device can derive the TA 376 from the TA 374 because the terminal device does not know the realized TAE. Therefore, if the realized TAE≠0 and is not known by the terminal device, the terminal device may not be able to accurately derive the TA 376 from the TA 374, and as a result, the UL time alignment error on the TRP 355 is equal to the realized TAE 370.

[0054] It should also be noted that a timing advance command (TAC) may be used to inform the terminal device of the amount of time it needs to advance its UL transmission. The TAC may be in the medium access control (MAC) control element (CE) or included in the random access response (RAR). The TA is controlled by the MAC layer and may be implemented at the physical layer. The TAC may conform to 3GPP standards.

[0055] In some exemplary embodiments, there may be mTRPs, e.g., N TRPs, and operations involving mTRPs may be performed. When M < N and M TACs are permitted or enabled, procedures are needed such that the terminal device can perform UL transmissions towards the N TRPs even if only M TACs can be utilized.

[0056] For example, if the terminal device is connected to a first TRP, there are two TRPs, and a second TRP is added after the terminal device is connected to the first TRP, the terminal device needs to have a procedure for determining an initial TA value for uplink transmission to the second TRP. In this procedure, it is desirable not to consume too many resources such as random access control channel (RACH) resources. It should also be noted that, in order to shorten the handover interruption time, the terminal device may acquire the TA values of a set of candidate target cells before performing cell switching. However, this may result in the need to acquire multiple TA values, and may impose additional inter-cell signaling overhead and delay to adjust RACH-based TA acquisition or update.

[0057] Therefore, there are N TRPs corresponding to N cells. When the network provides TA values or commands only for M < N TRPs, that is, for M cells, the terminal device can calculate the TA values of the remaining N - M TRPs. The terminal device may be able to calculate the timing differences of the remaining N - M TRPs using downlink reference signals (DL-RS) such as SSB, CSI-RS, or PT-RS. However, since the terminal device does not recognize the realized TAE between TRPs, these differences may be inaccurate or incorrect. However, to obtain the accurate TA values of the N - M TRPs, it is necessary to know the realized TAE between TRPs. The realized TAE between TRPs may depend on various aspects such as deployment or hardware implementation of the TRP. The terminal device may recognize the predefined maximum value of TAE among multiple TRPs, but the realized TAE value may not be recognized by the terminal device.

[0058] FIG. 4 illustrates an exemplary embodiment in which there is an implemented TAE that is not known to the terminal device. In this exemplary embodiment, the network provides terminal device 400 with a TA value for TRP 420 using TA command 425. This is illustrated in exemplary scenario 450 of FIG. 4. Thus, terminal device 400 is unaware of implemented TAE 430 and would use a RACH toward TRP 422 if it were to connect to TRP 422. Meanwhile, in exemplary scenario 455, the network provides terminal device 400 with TA command 425 and TA command 427, which indicates the TA value for TRP 422. In this exemplary scenario, there are also two additional TRPs, namely, TRPs 424 and 426. Terminal device 400, in this exemplary embodiment, is aware of a TAE requirement that sets the maximum value of TAE to 1000 ns, but the terminal device is unaware of implemented TAEs 435, 440, and 445. However, it is beneficial for the terminal device 400 to be able to determine the implemented TAEs 440 and 445 and, based thereon, and based on the received timing difference, also calculate the TA values ​​of TRP 424 and TRP 426.

[0059] In the context of this specification, TRP is understood to refer to and cover intra-cell and inter-cell scenarios. In intra-cell scenarios, multiple TRPs belong to the same cell and therefore have the same physical cell ID (PCI). In inter-cell scenarios, multiple TRPs have different PCIs and therefore belong to different cells. It should also be noted that some TRPs may be located in the same access node and some in different access nodes. Since the functionality of an access node may consist of a DU part that is located differently from the CU, a DU may coexist with one or more TRPs. Therefore, the TRP, DU, and CU may all be understood as part of the network and may also be referred to as network entities.

[0060] In an exemplary embodiment, the terminal device may use a procedure for determining the TA value when there are N TRPs and the number of TA values is M even though M < N. Determination may refer to obtaining the TA value or updating the TA value. The network may group TRPs having a realized TAE value considered small, for example, based on a criterion such as being below or equal to a threshold. In other words, there is an upper limit value, i.e., a threshold, and the realized TAE value is limited by that threshold. Such a group may be understood as a TAE group (TAEG). For example, the network may configure a group of TRPs such that the maximum realized TAE between two TRPs within the same TAEG is below a specific threshold. The threshold may be explicitly defined, for example, as 500 ns in the specification. Alternatively, the threshold may be determined by the network, possibly based on TA accuracy requirements. The network may be understood as any suitable entity within the network, such as an access node that may include one or more of the TRPs. In this exemplary embodiment, when multiple TAEGs are created, for each TAEG that may be used to provide services to the terminal device, the TA loop of at least one TRP belonging to the TAEG has already been initialized. The at least one TRP may sometimes be called the primary TRP. The criteria for creating TAEGs vary depending on the deployment of the TRPs and the network topology. TAEGs may be created statically, for example, as part of operations, administration, and maintenance (OAM). They may also be created dynamically. Note that dynamically updating an existing TAEG may also be understood as dynamically creating a TAEG. The advantage of creating TAEGs statically is simplicity. On the other hand, the advantage of creating TAEGs dynamically is that it may be useful in specific deployments, such as the movement of TRPs on mobile terminal devices or drones.It should also be noted that within one TAEG, the TAE may be small enough that the terminal device does not need to use the RACH to switch or add a transmission configuration indicator (TCI) state.

[0061] Next, in this exemplary embodiment, the network may provide signaling to the terminal device indicating the created TAEG(s). This may be done using a TAEG message. This message may be sent, for example, by the TRP serving the terminal device. The serving TRP may be the primary TRP, which is the TRP to which the terminal device is connected. The message may comprise information about the created TAEG. Because the terminal device is already connected to the primary TRP and TA loops have already been initialized for TRPs in the same TAEG, the TRPs may each send a message comprising information about other TRPs comprised in the same TAEG. The message may also optionally comprise information about thresholds used in creating the TAEG.

[0062] The terminal device may then measure the received DL RS, such as SSB or CSI-RS or PT-RS, and based on the measurement, estimate, for each TAEG, the RTD between the primary TRP and other TRPs in the same TAEG, which may be understood as secondary TRPs.

[0063] Since the TAE realized in the TAEG is considered small, the terminal device may also estimate the TA for the secondary TRP, and the estimation may be considered sufficiently accurate. The estimation may be determined as follows: TA secondary =TA primary +2*RTD

[0064] Therefore, the terminal device can determine the required TA values ​​for all N TRPs, and thus the terminal device can also avoid RACH-based procedures, which are considered slow and resource-consuming. Therefore, the terminal device obtains the TA value of the primary TRP and, based on the measured RTD, can determine the TA value of the secondary TRP, so that a connection to the secondary TRP can be established without prior transmission of a random access preamble to the secondary TRP. It should also be noted that the terminal device determines the TA value of the secondary TRP rather than receiving it from the network. The TA value of the secondary TRP can also be understood as an offset to the TA value of the primary TRP or another predefined value.

[0065] FIG. 5A illustrates another exemplary embodiment in which multiple TRPs exist and terminal device 540 is connected to a primary TRP. In this exemplary embodiment, there are six TRPs: TRPs 510, 515, 520, 525, 530, and 535. Terminal device 540 is connected to TRP 515, which in this embodiment is its primary TRP. A TA loop has already been initiated in TRP 515. In this example, network deployment allows the network to create two TAEGs: TAEGs 500 and 505. Creating a TAEG can also be understood as determining a TAEG. TAEG 500 includes TRPs 510, 515, 520, and 525, and the maximum TAE achieved within this group is set to 300 ns in this exemplary embodiment. TAEG 505 includes TRPs 530 and 535, and the maximum TAE achieved within this group is also set to 300 ns in this exemplary embodiment. The terminal device 540 may be informed of TAEG1 by the TRP 515 sending the TAEG configuration 550 to the terminal device 540, and the terminal device 540 may then estimate the RTD between the TRP 515 and, for example, the TRP 525 based on the DL RS. Thus, the terminal device 540 may calculate the TA of the TRP 525 as TA525=TA515+2 *RTD, thereby also avoiding a RACH procedure for TCI switching or addition 555. Thus, in Figure 5A, the illustrated exemplary embodiment shows TAEG signaling for grouping TRPs with small realized TAEs to avoid the need for a RACH procedure for TCI switching or addition.

[0066] On the other hand, in FIG. 5B, the exemplary embodiment is similar to the exemplary embodiment of FIG. 5A, but in this exemplary embodiment, the terminal device 540 connects to a TRP 535 belonging to a TAEG where there is no TRP in this TAEG in which the TA loop was initiated, and therefore, in this exemplary embodiment, a RACH procedure 560 is required.

[0067] 6 illustrates a signaling chart according to an exemplary embodiment. In this exemplary embodiment, there is a network to which a terminal device 610 is connected. The network has different network entities. In this exemplary embodiment, the network includes entities such as a DU / CU 600 and TRPs 601, 602, 603, 604, 605, and 606, at least some of which may be located in the same access node or in different access nodes. It should also be noted that in some examples, a combination of two or more network entities may be understood as one network entity. Thus, the signaling illustrated in this signaling chart occurs between the terminal device 610 and the network, and the network may be understood to refer to any appropriate network entity.

[0068] In this exemplary embodiment, the network determines and therefore creates two TAEGs. The first TAEG comprises TRPs 601, 602, 603, and 604. The second TAEG comprises TRPs 605 and 606. In some other exemplary embodiments, there may be more than two TAEGs, and / or the TAEGs may comprise a different number of TRPs. In this exemplary embodiment, the terminal device 610 is served by the TRP 601. Thus, the terminal device 610 measures the other TRPs 602, 603, 604, 605, and 606. Thus, the terminal device may measure other cells. The terminal device then transmits a measurement report 615 to the network entity 600, which may comprise a DU and / or CU. The network entity 600 then determines (620) whether to establish intra-cell or inter-cell mTRP or carrier aggregation, or to prepare for layer 1 or layer 2 triggered mobility (LTM), which requires mTRP TA acquisition.

[0069] The network entity 600 then sends 622 a response, which is a radio resource control (RRC) configuration or reconfiguration, to the terminal device 610. In other words, the terminal device 610 receives from the network entity 600 a configuration having a TA acquisition configuration comprising a TAEG grouping, i.e., a grouping of a first TAEG and a second TAEG. Once the grouping is indicated to the terminal device 610, the terminal device 610 may start transmitting towards a TRP other than the primary TRP 601 that is included in the first TAEG and serves the terminal device 610. The initiation may be performed using an initial TA based on the TA of another TRP in the group. Furthermore, the TA acquisition configuration may further include one or more of: indicating the primary TRP and secondary TRPs in the TAEG; a time adjustment timer (TAT); a resource configuration for RACH-based or SRS-based TA acquisition for the primary TRP; a resource and measurement configuration for non-RACH-based TA acquisition for the secondary cell, including measurement gaps and measurement times; and accuracy requirements for the TA acquisition procedure, which may require different levels of accuracy for different use cases, such as mTRP or mobility. Furthermore, the network may configure the terminal device 610 to calculate and apply the TA with higher accuracy than the conventional requirements to compensate for variations in TAE between TRPs in each TAEG. Furthermore, the configuration may indicate the identity of the TRP 601, which is the primary TRP, which is then used to self-determine the TA values ​​of the other TRPs. Optionally, the network may provide the terminal device 610 with information regarding the beams of the primary and / or secondary TRPs used to calculate or otherwise acquire the RTD, thereby also acquiring the TA value. The information regarding the beam may include, for example, a TCI state ID.

[0070] The terminal device 610 may then send a response 624, which may be an RRC configuration response or a reconfiguration response, to the network entity 600. The response 624 indicates the applicability of the proposed TA configuration. The terminal device 610 may also request an update if necessary.

[0071] The terminal device 610 then triggers or has already triggered TA acquisition 626 towards the TRP 601 and triggers TA acquisition 628 towards the TRP 605. The triggered TA acquisition 626 and 628 is based on a RACH or SRS transmission.

[0072] The terminal device then determines, or in other words, calculates 630, the TAs of the TRPs 602, 603, 604, and 606 based on the RTD measurements from the reference signals transmitted by the TRPs, the received TAEG information, and the TA knowledge of the primary TRPs, TRPs 601 and 605, in their respective TAEGs. In this exemplary embodiment, the downlink reference signal, DL-RS, may be an SSB or a CSI-RS. TRP 601 transmits DL-RS 631, TRP 602 transmits DL-RS 632, TRP 603 transmits DL-RS 633, TRP 604 transmits DL-RS 634, TRP 605 transmits DL-RS 635, and TRP 606 transmits DL-RS 636.

[0073] The terminal device 610 may then transmit a TA acquisition report 640 to the network entity 600 indicating whether TA acquisition was successful. Optionally, the calculated TA value may also be transmitted. Successful TA acquisition may mean, for example, that the terminal device 610 was able to execute a process to self-determine the TA of the TRPSs 602, 603, 604, and 606 based on RTD measurements from reference signals transmitted by the TRPs, received TAEG information, and the TA knowledge of the primary TRPs, TRPs 601 and 605, within their respective TAEGs. Additionally or alternatively, the terminal device 610 may subsequently receive from the network a TA adjustment command including a TA offset relative to the TA value currently used by the terminal device 610 after connecting to a secondary TRP. The absence of such a command or the inclusion of a small TA value (i.e., a value below a predetermined or configured threshold) in the command may indicate that the secondary TRP's calculated TA value is correct and, therefore, that TA acquisition by the secondary TRP was successful.

[0074] In response, the network entity 600 transmits to the terminal device 610, based on the received TA acquisition report 640, further TA configuration for TA reconfiguration or configuration regarding how the terminal device 610 can update the acquired TA value. Update may also be understood as tracking. Furthermore, the network entity 600 may transmit a TA adjustment command to modify the TA value available at the terminal device 610. Modification may also be understood as correction, adjustment, or reacquisition. Upon request, the network entity 600 may additionally or instead transmit an update of the TAEG and / or the realized TAE threshold value used as a criterion for determining the group.

[0075] Based on further configuration, the terminal device 610 may perform TA reacquisition at 650. This reacquisition may be based on the DL-RS from the TRP. The DL-RS may be SSB or CSI-RS. TRP 601 transmits DL-RS 651, TRP 602 transmits DL-RS 652, TRP 603 transmits DL-RS 653, TRP 604 transmits DL-RS 654, TRP 605 transmits DL-RS 655, and TRP 606 transmits DL-RS 656.

[0076] Then, in this exemplary embodiment, connections 660 and 665 are established to TRP 602 and TRP 603 without a RACH procedure. Note that in other exemplary embodiments, connections to other secondary TRPs may also be established. The connections may be triggered by the terminal device 610 or the network, and the connections may be for communication of handover to other TRPs.

[0077] 7 shows a flowchart according to an exemplary embodiment. In this exemplary embodiment, as shown in block 700, a terminal device is connected to M TRPs, and the terminal device receives signaling for one or more new TRPxs and their associated transmission configuration indications (TCIs). Based on the signaling, the terminal device can then connect to the one or more new TRPxs. Signaling may be received separately for each of the one or more new TRPxs, resulting in corresponding signaling for each of the one or more new TRPs indicating the TRP and its associated TCI. Additionally, the TAEG for the one or more new TRPxs may also be provided in the received signaling.

[0078] Next, in block 705, the terminal device determines whether the TRPx to be added belongs to the same TAEG as one of the number M TRPs to which the terminal device is already connected and for which UL synchronization has already been performed. If not, the terminal device performs a RACH procedure toward the TRPx to be added to obtain an initial TA value in block 710. If yes, the terminal device proceeds to block 720 and selects a TRPy from the M TRPs that is in the same TAEG as the new TRPx to which the connection is to be established. Thus, the terminal device is configured to add the new TRPx to the connected mTRP without a RACH procedure to obtain an initial TA value.

[0079] Then, in block 730, the terminal device estimates the RTD between the new TRPx and TRPy, which are in the same TAEG as the TRPx to be added, and in block 740, the terminal device calculates the initial TA value to be used for the TRPx.

[0080] 8 illustrates the TAE in two different exemplary scenarios 800 and 805. In the exemplary scenario 800, the TAE 810 is a predetermined TAE according to the specifications, which is equal to 3 us in this exemplary embodiment. The TAE 810 is illustrated along a timeline. Since the TAE requirement is 3 us, the terminal device must consider that the timing difference between any two TRPs can be up to 3 us.

[0081] In exemplary scenario 805, there are two TAEGs 820 and 825. TAEG 820 is provided with two TRPs, TRP1 and TRP2, and the implemented TAE is, for example, 500 ns. TAEG 825 is also provided with two TRPs, TRP3 and TRP4. The implemented TAE in TAEG 825 is, for example, 300 ns. Thus, in exemplary scenario 805, the terminal device is notified of the TAEG group by the network, the TRPs within the group are synchronized more precisely than in exemplary embodiment 800, and the implemented TAE is limited.

[0082] The network may use any suitable method to notify the terminal device of the TAEG. For example, the TAEG may be defined as part of the cell group configuration in a manner similar to the TAG configuration. The TAEG configuration may be denoted, for example, as TAEG config and may have the following exemplary structure: TAEG-Config ::= SEQUENCE { taeg-ToReleaseList SEQUENCE (SIZE (1..maxNrofTAEGs)) OF TAEG-Id, taeg-ToAddModList SEQUENCE (SIZE (1..maxNrofTAEGs)) OF TAEG } TAEG ::= SEQUENCE { tag-Id TAG-Id, timeAlignmentAcuuracyRequirement timeAlignmentAcuuracyRequirementValues ​​OPTIONAL } TAG-Id ::= INTEGER (0..maxNrof TAEGs-1) timeAlignmentAccuracyRequirementValues ​​::= ENUMERATED {nsec10, nsec50, nsec500}

[0083] For example, in an intra-cell scenario where TRPs have the same PCI-ID but different SSB-indexes, such as TCI state IDs, the association between TAs and TRPs can be defined in various ways. For example, a TA may be associated with a TCI state, or a TA may be associated with a CORESETPoolIndex. In one exemplary scenario, RRC configuration, two TRPs may be implicitly represented by two different control resource set (CORESET) groups, each of which may be identified by the value of the RRC parameter CORESETPoolIndex. In this exemplary scenario, a similar approach can be applied to the association of TAEGs, such that a TAEG is associated with one or more TCI states or CORESETPoolIndexes.

[0084] As described above, the TAEG may be used to initialize the TA loop of the secondary TRP. Furthermore, the above-described example embodiments may also be applicable to tracking the TA of the secondary TRP. The tracking may be performed as a relative offset of the TA of the secondary TRP relative to the TA of the primary TRP. For example, when a single TA loop is used, if a terminal device is transmitting to multiple TRPs with the same TAEG, it may be beneficial for the network side to change the role of the primary TRP by selecting another TRP with the same TAEG to which the terminal device is connected as the primary TRP. This allows the primary TRP to be selected as the one that minimizes the maximum TAE within the group. Furthermore, the primary TRP may be selected as the one that minimizes the average TAE within the group. Furthermore, the primary TRP may also be selected as the one that minimizes the sum of the squares of the TAE within the group.

[0085] Therefore, the above-described exemplary embodiment has advantages such as the terminal device not needing prior knowledge of the TAE between the primary and secondary TRPs to derive an accurate TA value for the secondary TRP. By grouping TRPs into TAE groups where the maximum value of the generated TAE remains below a certain threshold, the terminal device can ignore the TAE when estimating the TA value for the TRPs in this TAE group. The estimated TA value can be considered accurate enough for the terminal device to use as the applicable TA value.

[0086] 9 illustrates an apparatus 900, which may be a device such as a terminal device or may be included in a terminal device, according to an exemplary embodiment. The apparatus 900 includes a processor 910. The processor 910 interprets computer program instructions and processes data. The processor 910 may include one or more programmable processors. The processor 910 may include programmable hardware with embedded firmware, or alternatively or additionally, may include one or more application-specific integrated circuits (ASICs).

[0087] The processor 910 is coupled to the memory 920. The processor is configured to read and write data from and to the memory 920. The memory 920 may comprise one or more memory units. The memory units may be volatile or nonvolatile. Note that in some exemplary embodiments, there may be one or more nonvolatile memory units and one or more volatile memory units, or alternatively, there may be one or more nonvolatile memory units, or alternatively, there may be one or more volatile memory units. The volatile memory may be, for example, RAM, DRAM, or SDRAM. The nonvolatile memory may be, for example, ROM, PROM, EEPROM, flash memory, optical storage, or magnetic storage. In general, memory may be referred to as a non-transitory computer-readable medium. The memory 920 stores computer-readable instructions executed by the processor 910. For example, the non-volatile memory stores the computer-readable instructions, and the processor 910 executes the instructions using the volatile memory to temporarily store data and / or instructions.

[0088] The computer-readable instructions may be pre-stored in memory 920 or, alternatively or additionally, may be received by the device via an electromagnetic carrier signal and / or copied from a physical entity such as a computer program product. Execution of the computer-readable instructions causes the device 900 to perform the functions described above.

[0089] In the context of this specification, a "memory" or "computer-readable medium" may be any non-transitory medium or means that can contain, store, communicate, propagate, or transfer instructions used by or in connection with an instruction execution system, apparatus, or device, such as a computer.

[0090] The device 900 further comprises or is connected to an input unit 930. The input unit 930 comprises one or more interfaces for receiving user input. The one or more interfaces may comprise, for example, one or more motion and / or orientation sensors, one or more cameras, one or more accelerometers, one or more microphones, one or more buttons, and one or more touch detection units. Furthermore, the input unit 930 may comprise an interface to which external devices may connect.

[0091] The device 900 also comprises an output unit 940. The output unit comprises or is connected to one or more displays capable of rendering visual content, such as light emitting diode (LED) displays, liquid crystal displays (LCDs), and liquid crystal on silicon (LCoS) displays. The output unit 940 further comprises one or more audio outputs. The one or more audio outputs may be, for example, speakers or headphones.

[0092] The device 900 may further comprise a connectivity unit 950. The connectivity unit 950 enables wired and / or wireless connectivity to external networks. The connectivity unit 950 may be integrated into the device 900 or may comprise one or more antennas and one or more receivers to which the device 900 may be connected. The connectivity unit 950 may comprise an integrated circuit or set of integrated circuits that provide the device 900 with wireless communication capabilities. Alternatively, the wireless connection may be a hardwired application specific integrated circuit (ASIC).

[0093] It should be noted that the apparatus 900 may further comprise various components not shown in Figure 9. The various components may be hardware and / or software components.

[0094] The apparatus 1000 of FIG. 10 illustrates an exemplary embodiment of an apparatus that may be a network entity, such as an access node, or that may be included in a network entity. The apparatus may be, for example, a circuit or chipset applicable to a network entity for implementing the described embodiments. The apparatus 1000 may also be an electronic device comprising one or more electronic circuits. The apparatus 1000 may comprise communication control circuitry 1010, such as at least one processor, and at least one memory 1020 containing computer program code (software) 1022, which, together with the at least one processor, are configured to cause the apparatus 1000 to perform any one of the exemplary embodiments of an access node described above.

[0095] The memory 1020 may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory, and removable memory. The memory may comprise a configuration database for storing configuration data. For example, the configuration database may store a list of current neighboring cells and, in some embodiments, the structure of frames used in detected neighboring cells.

[0096] The apparatus 1000 may further comprise a communication interface 1030 comprising hardware and / or software for realizing a communication connection according to one or more communication protocols. The communication interface 1030 may provide the apparatus with wireless communication capabilities for communicating in a cellular communication system. The communication interface may, for example, provide a radio interface to a terminal device. The apparatus 1000 may further comprise another interface towards a core network, such as a network coordinator apparatus, and / or an access node of the cellular communication system. The apparatus 1000 may further comprise a scheduler 1040 configured to allocate resources.

[0097] Although the present invention has been described above with reference to examples according to the accompanying drawings, it is clear that the present invention is not limited thereto and can be modified in various ways within the scope of the appended claims. Therefore, all words and expressions should be interpreted broadly and are intended to describe, not limit, the embodiments. It will be obvious to those skilled in the art that with the advancement of technology, the concept of the present invention can be implemented in various ways. Furthermore, it will be obvious to those skilled in the art that the described embodiments may, but need not, be combined with other embodiments in various ways.

Claims

1. at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to: receiving a configuration from a network entity indicating a group of transmitting and receiving points having an achieved timing alignment error capped by a threshold; establishing a first connection to a first transmitting / receiving point comprised in said group; receiving a first timing advance value for an uplink transmission to the first transmitting / receiving point; determining that a second connection to a second transmitting / receiving point will be established; determining whether the second transmission / reception point is included in the group based on the received configuration; In response to the second transmitting / receiving point being provided in the group, measuring a reception time difference between the first transmission / reception point and the second transmission / reception point; determining a second timing advance value for uplink transmission to the second transmitting / receiving point based on the received first timing advance value and the measured reception time difference; A device that performs at least the above.

2. the second timing advance value is determined as TA2=TA1+2RTD; 2. The apparatus of claim 1, wherein TA1 and TA2 represent the first and second timing advance values, respectively, and RTD represents the measured reception time difference.

3. The apparatus according to claim 1 or 2, wherein the reception time difference is measured based on reference signals transmitted by the first transmitting / receiving point and the second transmitting / receiving point.

4. The device according to any one of claims 1 to 3, wherein the second connection is established without prior transmission of a random access preamble to the second transmitting / receiving point.

5. The device according to any one of claims 1 to 4, wherein said configuration further indicates an identification of said first transmission / reception point.

6. The device according to any one of claims 1 to 5, wherein the device is further adapted to send a request for updating the group and / or the threshold value.

7. The apparatus of any one of claims 1 to 6, wherein the apparatus is further caused to transmit a report indicating whether the determination of the second timing advance value was successful.

8. The apparatus of claim 7 , wherein the report further indicates the determined second timing advance value.

9. The apparatus of claim 7 or 8, wherein the apparatus is further adapted to receive, after the sending of the report, a command to adjust or reacquire the second timing advance value.

10. at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to: determining a group of transmitting and receiving points having a realized timing alignment error, the timing alignment error being upper bounded by a threshold; sending a configuration indicating said group to a terminal device; A device that performs at least the above.

11. a first connection is established between the terminal device and a first transmission / reception point comprised in the group, the first connection being associated with a first timing advance value for uplink transmission to the first transmission / reception point; a second connection is established between the terminal device and a second transmission / reception point comprised in the group, the second connection being associated with a second timing advance value for uplink transmission to the second transmission / reception point; the first timing advance value is received by the terminal device; 11. The apparatus of claim 10, wherein the second transmission timing advance value is determined by the terminal device based on the received first timing advance value and a reception time difference between the first transmission / reception point and the second transmission / reception point measured by the terminal device.

12. The apparatus of claim 11 , wherein the reception time difference is measured based on reference signals transmitted by the first transmission / reception point and the second transmission / reception point.

13. The device according to claim 11 or 12, wherein the second connection is established without the second transmitting / receiving point having previously received a random access preamble.

14. The device according to any one of claims 10 to 13, wherein said configuration further indicates an identification of said first transmission / reception point.

15. The apparatus of any one of claims 10 to 14, wherein the apparatus is further adapted to receive a request for updating the group and / or the threshold.

16. The apparatus of any one of claims 11 to 15, wherein the apparatus is further adapted to receive a report indicating whether the determination of the second timing advance value was successful.

17. The apparatus of claim 16 , wherein the report further indicates the determined timing advance value.

18. 18. The apparatus of claim 16 or 17, wherein the apparatus is further caused to, after the reception of the report, send a command to adjust or reacquire the second timing advance value.

19. The apparatus of any one of claims 10 to 18, wherein the apparatus is further caused to redetermine the groups.

20. receiving a configuration from a network entity indicating a group of transmitting and receiving points having an achieved timing alignment error capped by a threshold; establishing a first connection to a first transmitting / receiving point comprised in said group; receiving a first timing advance value for an uplink transmission to the first transmitting / receiving point; determining that a second connection to a second transmitting / receiving point will be established; determining whether the second transmission / reception point is included in the group based on the received configuration; In response to the second transmitting / receiving point being provided in the group, measuring a reception time difference between the first transmission / reception point and the second transmission / reception point; determining a second timing advance value for uplink transmission to the second transmitting / receiving point based on the received first timing advance value and the measured reception time difference; A method comprising:

21. determining a group of transmitting and receiving points having a realized timing alignment error, the timing alignment error being upper bounded by a threshold; sending a configuration indicating said group to a terminal device; A method comprising:

22. When executed by an apparatus, the apparatus: receiving a configuration from a network entity indicating a group of transmitting and receiving points having an achieved timing alignment error capped by a threshold; establishing a first connection to a first transmitting / receiving point comprised in said group; receiving a first timing advance value for an uplink transmission to the first transmitting / receiving point; determining that a second connection to a second transmitting / receiving point will be established; determining whether the second transmission / reception point is included in the group based on the received configuration; In response to the second transmitting / receiving point being provided in the group, measuring a reception time difference between the first transmission / reception point and the second transmission / reception point; determining a second timing advance value for uplink transmission to the second transmitting / receiving point based on the received first timing advance value and the measured reception time difference; 10. A computer-readable medium comprising program instructions for causing at least

23. When executed by an apparatus, the apparatus: determining a group of transmitting and receiving points having a realized timing alignment error, the timing alignment error being upper bounded by a threshold; sending a configuration indicating said group to a terminal device; 10. A computer-readable medium comprising program instructions for causing at least

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