WO2021047769A1

WO2021047769A1 - Apparatuses and methods for controlling transmission

Info

Publication number: WO2021047769A1
Application number: PCT/EP2019/074229
Authority: WO
Inventors: Esa Tapani Tiirola; Ilkka Antero Keskitalo; Lars Dalsgaard
Original assignee: Nokia Technologies Oy
Priority date: 2019-09-11
Filing date: 2019-09-11
Publication date: 2021-03-18

Abstract

Apparatuses and methods for communication are disclosed. A user terminal of a communication system obtains (500) at least two timing advance values to be used by the user terminal one at a time in transmission. The user terminal is configured to receive (502) a resource allocation for transmission and information defining which timing advance of the obtained values to use and transmit (504) on the allocated resource utilizing the timing advance.

Description

APPARATUSES AND METHODS FOR CONTROLLING TRANSMISSION Technical Field

The exemplary and non-limiting embodiments of the invention relate generally to communications.

Background

Wireless telecommunication systems are under constant development. There is a constant need for higher data rates and high quality of service. Reliability requirements are constantly rising and ways and means to ensure reliable connections and data traffic while keeping transmission delays minimal are constantly under development.

One possibility to increase reliability is to reduce interference on the signal path. Interference on the signal path may be caused by various causes, depending on the design of the physical layer of the communication system. Interference may be caused by nearby transmitters of the same communication system or by external signal sources. Within a communication system, the cause of interference may arise from transmitters in the same cell or from transmitter in nearly or adjacent cells.

To reduce interference, many different interference cancellation methods have been developed. For some of the possible solutions to effectively reduce interference, it would be advantageous to have common alignment with signals from different sources.

Brief description

According to an aspect of the present invention, there are provided apparatuses of claims 1 and 7.

According to an aspect of the present invention, there are provided methods of claims 15 and 20.

One or more examples of implementations are set forth in more detail in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims. The embodiments and or examples and features, if any, described in this specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various embodiments of the invention. Brief description of the drawings

In the following the invention will be described in greater detail by means of preferred embodiments with reference to the accompanying drawings, in which

Figure 1 illustrates a general architecture of an exemplary communication system;

Figure 2 illustrates an example of frame structure design;

Figure 3 illustrates examples of various interference situations;

Figure 4A and 4B illustrate an example of symbol misalignment;

Figure 5 is a flowchart illustrating some embodiments of the invention;

Figure 6 illustrates an embodiment;

Figures 7A and 7B illustrates examples of timing of signals;

Figure 8 is a flowchart illustrating some embodiments of the invention;

Figures 9, 10 and 11 illustrate examples of apparatuses applying some embodiments of the invention.

Detailed description of some embodiments

In the following, different exemplifying embodiments will be described using, as an example of an access architecture to which the embodiments may be applied, a radio access architecture based on long term evolution advanced (LTE Advanced, LTE-A) , enhanced LTE (eLTE), or new radio (NR, 5G), without restricting the embodiments to such an architecture, however. It is obvious for a person skilled in the art that the embodiments may also be applied to other kinds of communications networks having suitable means by adjusting parameters and procedures appropriately. Some examples of other options for suitable systems are the universal mobile telecommunications system (UMTS) radio access network (UTRAN or E-UTRAN), long term evolution (LTE, the same as E-UTRA), wireless local area network (WLAN or WiFi), worldwide interoperability for microwave access (WiMAX), Bluetooth®, personal communications services (PCS), ZigBee®, wideband code division multiple access (WCDMA), systems using ultra-wideband (UWB) technology, sensor networks, mobile ad-hoc networks (MANETs) and Internet Protocol multimedia subsystems (IMS) or any combination thereof.

Fig. 1 depicts examples of simplified system architectures only showing some elements and functional entities, all being logical units, whose implementation may differ from what is shown. The connections shown in Fig. 1 are logical connections; the actual physical connections may be different. It is apparent to a person skilled in the art that the system typically comprises also other functions and structures than those shown in Fig. 1.

The embodiments are not, however, restricted to the system given as an example but a person skilled in the art may apply the solution to other communication systems provided with necessary properties.

The example of Fig. 1 shows a part of an exemplifying radio access network.

Fig. 1 shows user devices 100 and 102 configured to be in a wireless connection on one or more communication channels in a cell with an access node, a distributed unit or an (e/g)NodeB) 104 providing the cell. The physical link from a user device to a (e/g)NodeB is called uplink or reverse link and the physical link from the (e/g)NodeB to the user device is called downlink or forward link. It should be appreciated that (e/g)NodeBs or their functionalities may be implemented by using any node, host, server or access point etc. entity suitable for such a usage.

A communications system typically comprises more than one (e/g)NodeB in which case the (e/g)NodeBs may also be configured to communicate with one another over links, wired or wireless, designed for the purpose. These links may be used for data and signaling purposes. The (e/g)NodeB is a computing device configured to control the radio resources of communication system it is coupled to. The (e/g)NodeB may also be referred to as a base station, an access point or any other type of interfacing device including a relay station capable of operating in a wireless environment. The (e/g)NodeB includes or is coupled to transceivers. From the transceivers of the (e/g)NodeB, a connection is provided to an antenna unit that establishes bi-directional radio links to user devices. The antenna unit may comprise a plurality of antennas or antenna elements. The (e/g)NodeB is further connected to core network 106 (CN or next generation core NGC). Depending on the system, the counterpart on the CN side can be a serving gateway (S-GW, routing and forwarding user data packets), packet data network gateway (P-GW), for providing connectivity of user devices (UEs) to external packet data networks, or mobile management entity (MME), etc. The core network further comprises a Core Access and Mobility Management Function, AMF, a Session Management Function, SMF, which is responsible for subscriber sessions, and User Plane Function, UPF.

The user device (also called UE, user equipment, user terminal, terminal device, etc.) illustrates one type of an apparatus to which resources on the air interface are allocated and assigned, and thus any feature described herein with a user device may be implemented with a corresponding apparatus, such as a relay node. An example of such a relay node is a layer 3 relay (self-backhauling relay) or a layer 2 relay (Integrated Access and Backhaul) towards the base station.

The user device typically refers to a portable computing device that includes wireless mobile communication devices operating with or without a subscriber identification module (SIM), including, but not limited to, the following types of devices: a mobile station (mobile phone), smartphone, personal digital assistant (PDA), handset, device using a wireless modem (alarm or measurement device, etc.), laptop and/or touch screen computer, tablet, game console, notebook, and multimedia device. It should be appreciated that a user device may also be a nearly exclusive uplink only device, of which an example is a camera or video camera loading images or video clips to a network. A user device may also be a device having capability to operate in Internet of Things (loT) network which is a scenario in which objects are provided with the ability to transfer data over a network without requiring human-to-human or human-to-computer interaction. One technology in the above network may be denoted as narrowband Internet of Things (NB-lot). The user device may also be a device having capability to operate utilizing enhanced machine-type communication (eMTC). The user device may also utilize cloud. In some applications, a user device may comprise a small portable device with radio parts (such as a watch, earphones or eyeglasses) and the computation is carried out in the cloud. The user device (or in some embodiments a layer 3 relay node) is configured to perform one or more of user equipment functionalities. The user device may also be called a subscriber unit, mobile station, remote terminal, access terminal, user terminal or user equipment (UE) just to mention but a few names or apparatuses.

Various techniques described herein may also be applied to a cyber physical system (CPS) (a system of collaborating computational elements controlling physical entities). CPS may enable the implementation and exploitation of massive amounts of interconnected 1CT devices (sensors, actuators, processors microcontrollers, etc.) embedded in physical objects at different locations. Mobile cyber physical systems, in which the physical system in question has inherent mobility, are a subcategory of cyber-physical systems. Examples of mobile physical systems include mobile robotics and electronics transported by humans or animals. Additionally, although the apparatuses have been depicted as single entities, different units, processors and/or memory units (not all shown in Fig. 1) may be implemented.

5G enables using multiple input - multiple output (MIMO) antennas, perhaps more base stations or nodes than the LTE (a so-called small cell concept), including macro sites operating in co-operation with smaller stations and employing a variety of radio technologies depending on service needs, use cases and/or spectrum available. 5G mobile communications support a wide range of use cases and related applications including video streaming, augmented reality, different ways of data sharing and various forms of machine type applications (such as (massive) machine-type communications (mMTC), including vehicular safety, different sensors and real-time control. 5G is expected to have multiple radio interfaces, namely below 6GHz, and mmWave, and also being integrable with existing legacy radio access technologies, such as the LTE. Integration with the LTE may be implemented, at least in the early phase, as a system, where macro coverage is provided by the LTE and 5G radio interface access comes from small cells by aggregation to the LTE. In other words, 5G is planned to support both inter-RAT operability (such as LTE-5G) and inter-Rl operability (inter-radio interface operability, such as below 6GHz - cmWave, above 6GHz -mmWave). One of the concepts considered to be used in 5G networks is network slicing in which multiple independent and dedicated virtual sub-networks (network instances) may be created within the same infrastructure to run services that have different requirements on latency, reliability, throughput and mobility.

The current architecture in LTE networks is fully distributed in the radio and fully centralized in the core network. The low latency applications and services in 5G require to bring the content close to the radio which leads to local break out and mobile edge computing (MEC). 5G enables analytics and knowledge generation to occur at the source of the data. This approach requires leveraging resources that may not be continuously connected to a network such as laptops, smartphones, tablets and sensors. MEC provides a distributed computing environment for application and service hosting. It also has the ability to store and process content in close proximity to cellular subscribers for faster response time. Edge computing covers a wide range of technologies such as wireless sensor networks, mobile data acquisition, mobile signature analysis, cooperative distributed peer-to-peer ad hoc networking and processing also classifiable as local cloud/fog computing and grid/mesh computing, dew computing, mobile edge computing, cloudlet, distributed data storage and retrieval, autonomic self-healing networks, remote cloud services, augmented and virtual reality, data caching, Internet of Things (massive connectivity and/or latency critical), critical communications (autonomous vehicles, traffic safety, real-time analytics, time- critical control, healthcare applications).

The communication system is also able to communicate with other networks, such as a public switched telephone network or the Internet 112, or utilize services provided by them. The communication network may also be able to support the usage of cloud services, for example at least part of core network operations may be carried out as a cloud service (this is depicted in Fig. 1 by "cloud" 114). The communication system may also comprise a central control entity, or a like, providing facilities for networks of different operators to cooperate for example in spectrum sharing.

Edge cloud may be brought into radio access network (RAN) by utilizing network function virtualization (NVF) and software defined networking (SDN). Using edge cloud may mean access node operations to be carried out, at least partly, in a server, host or node operationally coupled to a remote radio head or base station comprising radio parts. It is also possible that node operations will be distributed among a plurality of servers, nodes or hosts. Application of cloudRAN architecture enables RAN real time functions being carried out at the RAN side (in a distributed unit, DU 104) and non-real time functions being carried out in a centralized manner (in a centralized unit, CU 108).

It should also be understood that the distribution of labor between core network operations and base station operations may differ from that of the LTE or even be non-existent. Some other technology advancements probably to be used are Big Data and all-IP, which may change the way networks are being constructed and managed. 5G (or new radio, NR) networks are being designed to support multiple hierarchies, where MEC servers can be placed between the core and the base station or nodeB (gNB). It should be appreciated that MEC can be applied in 4G networks as well.

In an embodiment, 5G may also utilize satellite communication to enhance or complement the coverage of 5G service, for example by providing backhauling. Possible use cases are providing service continuity for machine-to- machine (M2M) or Internet of Things (loT) devices or for passengers on board of vehicles, or ensuring service availability for critical communications, and future railway/maritime/aeronautical communications. Satellite communication may utilize geostationary earth orbit (GEO) satellite systems, but also low earth orbit (LEO) satellite systems, in particular mega-constellations (systems in which hundreds of (nano) satellites are deployed). Each satellite 110 in the mega constellation may cover several satellite-enabled network entities that create on ground cells. The on-ground cells may be created through an on-ground relay node 104 or by a gNB located on-ground or in a satellite.

It is obvious for a person skilled in the art that the depicted system is only an example of a part of a radio access system and in practice, the system may comprise a plurality of (e/g)NodeBs, the user device may have an access to a plurality of radio cells and the system may comprise also other apparatuses, such as physical layer relay nodes or other network elements, etc. At least one of the (e/g)NodeBs may be a Home(e/g)nodeB. Additionally, in a geographical area of a radio communication system a plurality of different kinds of radio cells as well as a plurality of radio cells may be provided. Radio cells may be macro cells (or umbrella cells) which are large cells, usually having a diameter of up to tens of kilometers, or smaller cells such as micro-, femto- or picocells. The (e/g)NodeBs of Figure 1 may provide any kind of these cells. A cellular radio system may be implemented as a multilayer network including several kinds of cells. Typically, in multilayer networks, one access node provides one kind of a cell or cells, and thus a plurality of (e/g)NodeBs are required to provide such a network structure.

For fulfilling the need for improving the deployment and performance of communication systems, the concept of "plug-and-play" (e/g)NodeBs has been introduced. Typically, a network which is able to use "plug-and-play" (e/g)Node Bs, includes, in addition to Home (e/g)NodeBs (H(e/g)nodeBs), a home node B gateway, or HNB-GW (not shown in Fig. 1). A HNB Gateway (HNB-GW), which is typically installed within an operator’s network may aggregate traffic from a large number of HNBs back to a core network.

As mentioned, radio access network may be split into two logical entities called Central Unit (CU) and Distributed Unit (DU). In prior art, both CU and DU supplied by the same vendor. Thus, they are designed together and interworking between the units is easy. The interface between CU and DU is currently being standardized by 3GPP and it is denoted FI interface. Therefore, in the future the network operators may have the flexibility to choose different vendors for CU and DU. Different vendors can provide different failure and recovery characteristics for the units. If the failure and recovery scenarios of the units are not handled in a coordinated manner, it will result in inconsistent states in the CU and DU (which may lead to subsequent call failures, for example). Thus there is a need to enable the CU and DU from different vendors to coordinate operation to handle failure conditions and recovery, taking into account the potential differences in resiliency capabilities between the CU and DU.

Fig.2 illustrates an example of frame structure design defined for 5G (or NR). The proposed NR frame structure design supports slot-based operation (Type-A) and non-slot-based operation (Type-B). The duration of a slot is 14 OFDM symbols 200. Different slot types are illustrated in Fig. 2. These provide the basic support for both Time Division Duplex TDD and Frequency Division Duplex FDD.

Bi-directional downlink slot 202 may comprise downlink control Dc, downlink data Dd, guard period GP and uplink control Uc.

Downlink only slot 204 may downlink control Dc and downlink data Dd.

Bi-directional uplink slot 206 may comprise downlink control Dc, guard period GP, uplink data Ud and uplink control Ud.

Uplink only slot 208 may comprise uplink data Ud and uplink control

Uc.

For bi-directional slots 202, 206, slot format contains either downlink data or uplink data transmission together the corresponding downlink and uplink control. Bi-directional slot facilitates many crucial TDD functionalities in the NR frame structure, such as link direction switching between downlink and uplink, including guard period (GP) required for the link direction switching, fully flexible traffic adaptation between downlink and uplink and opportunity for low latency (in case slot length is selected to be short enough).

In all slots, multiplexing between downlink control, DL/UL data, guard period and uplink control is based primarily on time division multiplexing allowing fast energy efficient pipeline processing of control and data in the receiver. Physical Downlink Control Channel (PDCCH) may be conveyed in the downlink control symbol(s) located at the beginning of the slot (or the mini-slot).

In addition to bi-directional slots, also downlink-only slot 204 and uplink-only slot 208 formats are supported. These formats are needed at least in FDD mode, but also in certain TDD scenarios to allow longer transmission periods in same direction. An example of this is operation in unlicensed spectrum.

Fig.3 illustrates examples of various interference situations. In Fig.3, there is a gNB 300 maintaining a macro cell 302, and three gNBs 304, 306, 308 maintaining pico cells 310, 312, 314. Desired signals are denoted with solid lines and interfering signals with dashed lines. Cross-link interference in general may be divided into two categories. Transmission and reception point to transmission and reception point TRP-to-TRP (or DL-to-UL) interference is produced by a downlink, DL, transmitter in the proximity of a gNB receiving an uplink, UL, signal.

In the example of Fig.3, user terminal UT2 is transmitting uplink signal 316 to gNB 306. In the neighbouring cell gNB 304 is transmitting downlink signal 318 to user terminal UT1. This downlink signal is also received by gNB 306 and can be seen interfering 320 the uplink signal 312 of UT2.

User terminal to user terminal, UE-to-UE (or UL-to-DL) interference is created by an uplink transmitter in the close proximity of the user terminal receiving a downlink signal in the neighbouring cell.

In the example of Fig.3, the uplink signal 312, transmitted by UT2 is also received 322 by user terminal UT1 and interferes with the downlink signal 318 from gNB 304.

Co-channel interference situation is created when user terminal uplink transmission is interfered by uplink transmission of another user terminal in a neighbouring cell.

In Fig.3, user terminal UT2 is transmitting uplink signal 324 to gNB 308. This signal maybe interfered by an uplink signals 326, 328 transmitted by a nearby user terminal UT4 to gNB 300,

Generally, it can further be noted that in UT-to-UT interference scenario, the distance between the victim user terminal (e.g. UT1 in Fig. 3) and interfering user terminal (e.g. UT2 in Fig. 3) is relatively short in order for the interference to be noticeable. Thus, the symbols from the interfering user terminal can often be assumed to be received by the victim user terminal within the normal Cyclic Prefix, CP, duration. However, UT transmission timing depends on the distance to the serving base station. It is possible that the timing difference can be also larger than CP even UTs being close to each other.

The developed 5G (or new radio, NR) network may eventually support for example certain UT-to-UT interference mitigation schemes depending on the backhaul capacities between cells. Interference suppression by using advanced receivers can be considered as one efficient method for UT-to-UT interference handling. In order to enable usage of advanced receivers to mitigate UT-to-UT interference, it would be advantageous to provide support for cross-link orthogonal reference signals. Time alignment on symbol level between downlink and uplink is important to enable cross-link orthogonal reference signals and usage of advanced receivers. In other words, the symbol boundaries between downlink and uplink would need to be aligned with Cyclic Prefix accuracy at the receiver. Uplink-to- downlink / downlink-to-uplink switching times (defining the minimum timing advance, TA) can be considered relatively long compared to the NR symbol lengths.

Further, in case minimum timing advance is longer than Cyclic Prefix time, symbol alignment between downlink and uplink is not currently supported in the proposed NR bi-directional slot formats. This is illustrated in Fig. 4A and 4B (here propagation delay between gNB and UE is assumed to be close to zero). Therefore, advanced receivers and efficient interference mitigation can’t be supported with current 3GPP NR bi-directional slot formats. Advanced user terminal receivers can be e.g. linear receivers, such as MMSE (Minimum Mean Square Error) or IRC (Interference Rejection Combining), or non-linear receivers such as interference cancelling receivers.

In the example situation of Fig. 4A, gNBl is transmitting a downlink signal 400 to user terminal UT1. User terminal UT2 is transmitting uplink signal 402 to gNB2. This signal is seen 404 as interference by UT1.

Fig. 4B illustrates symbol misalignment in the situation of Fig. 4A. The same symbol notation is used as in Fig. 2. Fig. 4B shows slot structure 410 of downlink signal 400 received by UT1 and slot structure 412 of uplink signal 402 transmitted by UT2 and seen by UT1. Both signals comprise gaps 414, 416 which are minimum times required for switching uplink to downlink.

Downlink control transmissions are aligned 418 in both slot structures but there is symbol misalignment between uplink data and downlink data 420, and uplink control 422.

Fig. 5 is a flowchart illustrating some embodiments of the invention. Fig. 5 illustrates an example of the operation of an apparatus or a network element configured to operate as user terminal a part of a user terminal

In step 500 of Fig. 5, the apparatus is configured to obtain at least two timing advance values to be used by the apparatus one at a time in transmission. In an embodiment, the timing advance values are received as one timing advance value and one or more offsets to the value. The apparatus may be configured to calculate one or more additional timing advance values based on the received value and the offsets. In step 502 of Fig. 5, the apparatus is configured to control reception of a resource allocation for transmission and information defining which timing advance of the obtained values to use in the transmission. In an embodiment, information which timing advance of the obtained values to use is received at the same time as the resource allocation. In an embodiment, information which timing advance of the obtained values to use is received separately from the resource allocation. In an embodiment, information which timing advance of the obtained values to use is determined implicitly from a predefined parameter, e.g. resource type. For example, resource configured and/or indicated as uplink resource may correspond to one timing advance value, and resources configured and/or indicated as flexible resource may correspond to another timing advance value, respectively.

In step 504 of Fig. 5, the apparatus is configured to control transmission on the allocated resource utilizing the timing advance.

In an embodiment, the apparatus is configured to utilise the at least two timing advance values one at a time on a single uplink bandwidth part.

In an embodiment, the apparatus is configured to receive information on two different resource types and receive information which timing advance value is to be used on each type resource type. When receiving a resource allocation for transmission the apparatus obtains information of the resource type and selects the timing advance to be used based on the resource type.

In an embodiment, a part of the available time domain resources available for uplink transmission may be configured as "cross-link resources" or "flexible resources" while the remaining time domain resources may be categorised as "co-channel resources" or "uplink resources". The user terminals maybe configured to support two timing advance values (within a cell). Thus, when receiving a resource allocation to use a resource belonging to co-channel resources, the apparatus may be configured to utilise a first timing advance value and when receiving a resource allocation to use a resource belonging to cross-link resources, the apparatus may be configured to utilise a second timing advance value.

In an embodiment, the second timing advance value may be determined based on the first timing advance value to which an offset value is added. The offset value may be negative or positive. Depending on the duration of uplink transmission, the usage of the second timing advance value may involve puncturing (or rate matching) one (or more) symbol away from beginning or end of the transmitted uplink signal (depending on how the offset is done: negative or positive). In an embodiment, instead of puncturing/rate matching uplink transmission, the puncturing/rate matching can be made for downlink transmission preceding or following the uplink transmission in which the second timing advance value was used. It may be noted here that 5G or NR supports flexible starting/ending point for both uplink and downlink.

In an embodiment, the actual TA value to be used may be determined by uplink resource allocation. The offset value related to the second timing advance value may be indicated from gNB to the user terminal by means of higher layer signalling (Radio Resource Control RRC, Medium Access Control MAC) or by means of physical layer signalling.

The above solution utilising different timing offset values causes cross link interference (uplink to downlink) become symbol-level aligned at the UT1 (see e.g. Fig. 4A ).

Above and below the examples are for two timing advance values. However, in some embodiments there may be more than two timing advance values in use. These may be determined for different interference scenarios, e.g. according to location of the interfered user terminal(s) in the neighbouring cell. In the examples above and below, two timing advance values are used for simplicity.

There are various ways of determining the timing advance values. The first timing advance value related to co-channel resources, can be made according to prior art. Uplink measurements from Physical Random Access Channel PRACH, Sounding Reference Signal SRS and Demodulation Reference Signal DMRS can used for necessary uplink timing measurements at the gNB. In the prior art, gNB determines the target reception timing for uplink signal (with respect to downlink timing), and adjusts the Timing Advance command based on the that. The user terminal just follows the Timing Advance commands sent by gNB.

For the determination of the second timing advance value or the offset, two examples are disclosed. In the first example, the determination of the second timing advance value utilises user terminal measurements. In the second example, the determination is made by the network without user terminal measurements. It may be noted that combinations of these approaches are also possible.

Fig. 6 illustrates the first example. The starting situation may be as illustrated in Fig. 4A, where gNBl is transmitting a downlink signal 400 to user terminal UT1. User terminal UT2 is transmitting uplink signal 402 to gNB2. This signal is seen 404 as interference by UT1. The user terminal UT1 measures 600 Rx timing of the signal 404 transmitted by the user terminal UT2 located in the neighbouring cell. In an embodiment, the Rx timing measurement indicates the difference between the downlink Rx timing of UT1 and uplink Rx timing of UT2.

In an embodiment, the user terminal has received a command from the serving gNB to perform measurement and a measurement configuration related to cross-link interference. User terminals (UT2) in the neighbouring cell are configured to send SRS accordingly. The configuration may comprise a sounding reference signal SRS (or other signal used to measure cross-link timing), measurement configuration, SRS being transmitted with different (OFDM) symbol timing compared to a downlink signal and measurement reporting configuration. Based on the received measurement configuration the user terminal UT1 may measure the timing difference between configured SRS and the downlink symbol timing.

The UT1 transmits 602 information indicative to the Rx timing measurement to the serving gNBl. In an embodiment, the user terminal is configured to report the measured timing difference using Physical Uplink Control Channel PUCCH or Physical Uplink Shared Channel PUSCH, for example. The report maybe an Radio Resource Control, RRC, measurement report as well.

The gNBl conveys 604 the received information indicative to Rx timing measurement to the gNB serving the neighbouring cell, gNB2.

The gNB2 is configured to determine 606, based on the received information, the timing offset value in the cell such that cross-link interference (UL®DL) becomes symbol-level aligned at the UT1.

Next, the gNB2 conveys 608 the determined offset value to UT2, for example by means of higher layer signalling (RRC or MAC).

Finally, the UT2 utilises 610 the timing advance value in its transmission.

In the second example, the second timing advance value or the offset is determine by the network (such as gNBl, gNB2) without the related measurement by UT1. In the example of Fig.4, the serving gNB (gNB2) may determine the offset and indicate the offset to UT2 by higher layer signalling, RRC or MAC. The serving gNB may determine the offset e.g. based on cell geometry and other available information (such as location of dominant interferes). In an embodiment, the offset term can be cell-specific and it can determined based on the cell edge UEs. In an embodiment, the offset may also be bandwidth part specific, or user terminal specific. A gNB may apply guard band for simultaneous reception of uplink of signals (or bandwidth parts) having different offset value. This may be applied also for the simultaneous reception of user terminals with the first and the second timing advance values. The cell-specific offset term allows to compensate the Rx timing differences between adjacent cells e.g. due to different cell size.

In an embodiment, each gNB determines the timing advance values for the user terminals served by the gNB. In an embodiment, there may be a separate functionality in the network for determining the timing advance values. The functionality may be located in a gNB, or in some other network element. For example, it may be located in Operation & Maintenance, O&M, server or be a dedicated server for timing advance determination purposes, or a separate logical unit or function in the radio access network for topology management.

In an embodiment, to cope especially with the larger propagation delays in a heterogeneous network, other measurements such as RRM measurement results may be utilised to collect information about the relative received signal timing of neighbour cell downlink transmissions. These results can be used to set the offset to cover the extreme cases of the timing differences within the (heterogenous) network and allow the serving node to have appropriate puncturing of symbols in the "cross-link" resources/slots.

In an embodiment, gNB may be configured to transmit a first timing advance command to served user terminal. A network element, the gNB or other element may be configured to determine an offset value for creating a second timing advance command at the user terminal, and transmit the offset value to at least one user terminal.

The gNB serving the user terminal maybe configured to determine a resource type for uplink transmission of the user terminal. Based on the determined uplink resource type the gNB transmits uplink resource allocation with an indication on the uplink resource type (co-channel/uplink or cross link/flexible) for the user terminal. The indication may also be transmitted separately from the resource allocation.

The user terminal may be configured to receive a first timing advance command and receive the offset value. The user terminal may further be configured to determine a second timing advance command based on the first timing advance command and the offset value, receive uplink resource allocation containing an indication on the uplink resource type (co-channel or cross-link, for example) and, based on indicated resource type, transmit uplink signal based on a first or a second timing advance command.

Based on indicated resource type, the gNB is configured to receive uplink signal according to the first or the second timing advance command.

The proposed solution facilitates robust user terminal operation when using flexible Time Division Duplex, TDD, and/or various Integrated Access and Backhaul, 1AB, scenarios involving cross-link interference at the user terminal the proposed solution has small implementation complexity and it may be realised as a straightforward extension on top of the already agreed 5G or NR slot structures.

Uplink signal reception is still synchronous (between user terminals with the same offset value).

Figs. 7A and 7B illustrates embodiments of the invention. Fig. 7A illustrates timing of signals of UT1 and UT2 in the situation of Fig.4, in prior art situation when embodiments of the invention are not applied. Slot n illustrates a scenario when there is cross-link interference from UT2 uplink signal 702 to UT1 downlink signal 700. Slot n+1 illustrates a scenario without cross-link interference (i.e. co-channel resource is used). In slot n there is timing advance TAJJT2 704 used and in slot n+1 timing advance values TAJJTl 706 and TAJJT2 708 used. The same timing advance is applied in both slots. There is an Rx timing difference 710 between UT1 downlink signal 700 and UT2 uplink signal 702 as the interfering signal 702 is not symbol-level aligned with the desired signal 700 (from UT1 point of view).

Fig. 7B illustrates timing of signals of UT1 and UT2 in the situation of Fig.4, when embodiments of the invention are applied. Slot n illustrates a scenario when there is cross-link interference from UT2 uplink signal 702 to UT1 downlink signal 700. Slot n+1 illustrates a scenario without cross-link interference. In this case, the timing advance values in the co-channel slot n+1 are the same as in Fig. 7 A. However, in slot n, a second timing advance TAJJT2 720 is utilised. The slot comprises a punctured symbol 722. Now the UT2 uplink signal 702 and UT1 downlink signal 700 are aligned 724.

Fig. 8 is a flowchart illustrating some embodiments of the invention. Fig. 8 illustrates an example of the operation of an apparatus or a network element. The apparatus may be configured operate as base station or gNB or a part of a base station or it may be a network element other than gNB.

In step 800 of Fig. 8, the apparatus is configured to determine at least two timing advance values to be used by a user terminal one at a time in transmission. The determination may be based on measurements made by user terminal and/or base station or it may be based on other information, such as the location of the user terminal and the interfering terminals. In an embodiment, the timing advance values may be cell-specific.

In step 802 of Fig. 8, the apparatus is configured to control transmission to the user terminal of information on the timing advance values. If the apparatus is a gNB, it may transmit the information directly. If the apparatus is another network element, it may convey the information to the gNB serving the user terminal.

If the apparatus is a gNB, the apparatus may be configured to, in step 804 of Fig. 8, control transmission to the user terminal of a resource allocation for transmission and information which timing advance of the obtained values to use.

Further, if the apparatus is a gNB, the apparatus may be configured to receive uplink transmission from one or more user terminals, based on at least two timing advance values one at a time.

Figs. 9, 10 and 11 illustrate some embodiments. Fig. 9 illustrates a simplified example of an apparatus applying embodiments of the invention. In some embodiments, the apparatus may be a user terminal or a part of a user terminal, or any other entity of the communication system provided that the necessary inputs are available and required interfaces exists to transmit and receive required information.

Figs 10 and 11 illustrate simplified examples of an apparatus applying embodiments of the invention. In some embodiments, the apparatus may be a base station (gNB) or a part of a base station, or any other entity of the communication system provided that the necessary inputs are available and required interfaces exists to transmit and receive required information.

It should be understood that the apparatuses are depicted herein as examples illustrating some embodiments. It is apparent to a person skilled in the art that the apparatuses may also comprise other functions and/or structures and not all described functions and structures are required. Although the apparatuses has been depicted as one entity, different modules and memory may be implemented in one or more physical or logical entities.

The apparatus 900 of the example includes a control circuitry 902 configured to control at least part of the operation of the apparatus. The apparatus may comprise a memory 904 for storing data. Furthermore the memory may store software 906 executable by the control circuitry 902. The memory may be integrated in the control circuitry.

The apparatus may comprise one or more transceiver circuitries 908. The transceiver 908 may be configured to communicate wirelessly with other network elements such as gNBs. The transceiver may be connected to an antenna arrangement 910. The apparatus may further comprise user interface 912. the user interface may comprise a (touch sensitive) display, a microphone and a speaker, for example. The interfaces may be operationally connected to the control circuitry 902.

The software 906 may comprise a computer program comprising program code means adapted to cause the control circuitry 902 of the apparatus to perform the embodiments described above and in the claims.

The apparatus 1000 of the example includes a control circuitry 1002 configured to control at least part of the operation of the apparatus.

The apparatus may comprise a memory 1004 for storing data. Furthermore the memory may store software 1006 executable by the control circuitry 1002. The memory may be integrated in the control circuitry.

The apparatus may comprise one or more interface circuitries 1008, 1010. If the apparatus is a base station or a part of a base station one of the interfaces may be a transceiver 1008 configured to communicate wirelessly with user terminals. The transceiver may be connected to an antenna arrangement (not shown). Other interface (s) 1010 may connect the apparatus to other network elements of the communication system. The interface may provide a wired or wireless connection to the communication system. The interfaces may be operationally connected to the control circuitry 1002.

The software 1006 may comprise a computer program comprising program code means adapted to cause the control circuitry 1002 of the apparatus to perform the embodiments described above and in the claims.

In an embodiment, as shown in Fig. 11, at least some of the functionalities of the apparatus of Fig. 10 may be shared between two physically separate devices, forming one operational entity. Therefore, the apparatus may be seen to depict the operational entity comprising one or more physically separate devices for executing at least some of the described processes. Thus, the apparatus of Fig. 11, utilizing such shared architecture, may comprise a remote control unit RCU 1100, such as a host computer or a server computer, operatively coupled (e.g. via a wireless or wired network) to a remote radio head RRH 1102 located in the base station. In an embodiment, at least some of the described processes may be performed by the RCU 1100. In an embodiment, the execution of at least some of the described processes may be shared among the RRH 1102 and the RCU 1100.

In an embodiment, the RCU 1100 may generate a virtual network through which the RCU 1100 communicates with the RRH 1102. In general, virtual networking may involve a process of combining hardware and software network resources and network functionality into a single, software-based administrative entity, a virtual network. Network virtualization may involve platform virtualization, often combined with resource virtualization. Network virtualization may be categorized as external virtual networking which combines many networks, or parts of networks, into the server computer or the host computer (e.g. to the RCU). External network virtualization is targeted to optimized network sharing. Another category is internal virtual networking which provides network like functionality to the software containers on a single system. Virtual networking may also be used for testing the terminal device.

In an embodiment, the virtual network may provide flexible distribution of operations between the RRH and the RCU. In practice, any digital signal processing task may be performed in either the RRH or the RCU and the boundary where the responsibility is shifted between the RRH and the RCU may be selected according to implementation.

The steps and related functions described in the above and attached figures are in no absolute chronological order, and some of the steps may be performed simultaneously or in an order differing from the given one. Other functions can also be executed between the steps or within the steps. Some of the steps can also be left out or replaced with a corresponding step.

The apparatuses or controllers able to perform the above-described steps may be implemented as an electronic digital computer, which may comprise a working memory (RAM), a central processing unit (CPU), and a system clock. The CPU may comprise a set of registers, an arithmetic logic unit, and a controller. The controller is controlled by a sequence of program instructions transferred to the CPU from the RAM. The controller may contain a number of microinstructions for basic operations. The implementation of microinstructions may vary depending on the CPU design. The program instructions may be coded by a programming language, which may be a high-level programming language, such as C, Java, etc., or a low-level programming language, such as a machine language, or an assembler. The electronic digital computer may also have an operating system, which may provide system services to a computer program written with the program instructions.

As used in this application, the term 'circuitry' refers to all of the following: (a) hardware-only circuit implementations, such as implementations in only analog and/or digital circuitry, and (b) combinations of circuits and software (and/or firmware), such as (as applicable): (i) a combination of processor(s) or (ii) portions of processor(s)/software including digital signal processor(s), software, and memory(ies) that work together to cause an apparatus to perform various functions, and (c) circuits, such as a microprocessor(s) or a portion of a microprocessor(s), that require software or firmware for operation, even if the software or firmware is not physically present.

This definition of 'circuitry' applies to all uses of this term in this application. As a further example, as used in this application, the term 'circuitry' would also cover an implementation of merely a processor (or multiple processors) or a portion of a processor and its (or their) accompanying software and/or firmware. The term 'circuitry' would also cover, for example and if applicable to the particular element, a baseband integrated circuit or applications processor integrated circuit for a mobile phone or a similar integrated circuit in a server, a cellular network device, or another network device.

The computer program may be in source code form, object code form, or in some intermediate form, and it may be stored in some sort of carrier, which may be any entity or device capable of carrying the program. Such carriers include a record medium, computer memory, read-only memory, and a software distribution package, for example. Depending on the processing power needed, the computer program may be executed in a single electronic digital computer or it may be distributed amongst a number of computers.

The apparatus may also be implemented as one or more integrated circuits, such as application-specific integrated circuits ASIC. Other hardware embodiments are also feasible, such as a circuit built of separate logic components. A hybrid of these different implementations is also feasible. When selecting the method of implementation, a person skilled in the art will consider the requirements set for the size and power consumption of the apparatus, the necessary processing capacity, production costs, and production volumes, for example. In an embodiment, the apparatus comprises means for obtaining at least two timing advance values to be used by the apparatus one at a time in transmission, means for controlling reception of a resource allocation for transmission and information which timing advance of the obtained values to use and means for controlling transmission on the allocated resource utilizing the timing advance.

In an embodiment, the apparatus comprises means for determining at least two timing advance values to be used by a user terminal one at a time in transmission and means for controlling transmission of information on the timing advance values to the user terminal.

It will be obvious to a person skilled in the art that, as the technology advances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.

Claims

1. An apparatus comprising at least one processor; at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform: obtain at least two timing advance values to be used by the apparatus one at a time in transmission; control reception of a resource allocation for transmission, and information defining which timing advance of the obtained values to use; control transmission on the allocated resource utilizing the timing advance.

2. The apparatus of claim 1, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus further to perform: control reception of a timing advance value and one or more offsets to the value; calculate one or more additional timing advance values based on the received value and the offsets.

3. The apparatus of any preceding claim, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus further to perform: control reception information which timing advance of the obtained values to use separately from the resource allocation.

4. The apparatus of any preceding claim, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus further to perform: control reception information on two different resource types; control reception information which timing advance value is to be used on each type resource type; when receiving a resource allocation for transmission obtain information of the resource type; select the timing advance to be used based on the resource type.

5. The apparatus of any preceding claim, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus further to perform: receive a command to measure timing of transmission of a user terminal of an adjacent cell, compare difference of the measured timing to the timing of the transmission of the apparatus; transmit data on comparison to a serving base station.

6. The apparatus of any preceding claim, wherein the apparatus is configured to utilise the at least two timing advance values one at a time on a single uplink bandwidth part.

7. An apparatus comprising at least one processor; at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform: determine at least two timing advance values to be used by a user terminal one at a time in transmission and control transmission to the user terminal of information on the timing advance values.

8. The apparatus of claim 7, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus further to perform: control transmission to the user terminal of a resource allocation for transmission and information which timing advance of the obtained values to use.

9. The apparatus of claim 7, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus further to perform: receive uplink transmission from one or more user terminals, based on at least two timing advance values one at a time.

10. The apparatus of claim 8, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus further to perform: control reception from a neighboring base station of measurement results related to timing difference between a first signal and a second signal received by a user terminal in the neighboring cell, wherein the first signal is uplink transmission from a user terminal in the cell served by the apparatus and the second signal is a transmission in the neighboring cell; determine one or more timing advance values based on the measurement results.

11. The apparatus of claim 8, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus further to perform: determine a first timing advance value to synchronise uplink reception in the cell served by the apparatus; determine an offset to the first timing advance value, the offset being equal to the received timing difference, a second timing advance value being a sum of the first timing advance value and the offset; and control transmission of the timing advance value and the offset to a user terminal.

12. The apparatus of claim 8, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus further to perform: determine a first timing advance value to synchronise uplink reception in the cell served by the apparatus; control reception from a neighbouring base station of an offset to the first timing advance value, a second timing advance value being a sum of the first timing advance value and the offset.

13. The apparatus of claim 8, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus further to perform: determine one or more offsets to a timing advance value based on geometry of the cell served by the apparatus and location of one or more user terminals in a neighbouring cell; transmit the determined offsets to a base station serving neighbouring cell.

14. The apparatus of claim 7, wherein the determined timing advance values apply to all user terminals in a same cell.

15. A method in a user terminal of a communication system, comprising: obtaining at least two timing advance values to be used by the user terminal one at a time in transmission; controlling reception of a resource allocation for transmission and information defining which timing advance of the obtained values to use.

16. The method of claim 15, further comprising: controlling transmission on the allocated resource utilizing the timing advance.

17. The method of claim 15 or 16, further comprising: controlling reception information which timing advance of the obtained values to use separately from the resource allocation.

18. The method of any preceding claim 15 to 17, further comprising: controlling reception information on two different resource types;; controlling reception information which timing advance value is to be used on each type resource type; obtaining information of the resource type when receiving a resource allocation for transmission; selecting the timing advance to be used based on the resource type.

19. The method of any preceding claim 15 to 17, further comprising: receiving a command to measure timing of transmission of a user terminal of an adjacent cell, compare g difference of the measured timing to the timing of the transmission of the apparatus; transmitting data on comparison to a serving base station.

20. A method in a network element of a communication system, comprising: determining at least two timing advance values to be used by a user terminal one at a time in transmission and controlling transmission to the user terminal of information on the timing advance values.

21. The method of claim 20, further comprising: controlling transmission to the user terminal of a resource allocation for transmission and information which timing advance of the obtained values to use.

22. The method of claim 20 or 21, further comprising: receiving uplink transmission from one or more user terminals, based on at least two timing advance values one at a time.

23. The method of any preceding claim 20 to 22, further comprising: controlling reception from a neighbouring base station of measurement results related to timing difference between a first signal and a second signal received by a user terminal in the neighbouring cell, wherein the first signal is uplink transmission from a user terminal in the cell served by the apparatus and the second signal is a transmission in the neighbouring cell; determining one or more timing advance values based on the measurement results.

24. A computer program comprising instructions for causing an apparatus of a communication system to perform any of the method steps of claims 15 to 23.