WO2023144443A1

WO2023144443A1 - Enhancing connection quality after handover

Info

Publication number: WO2023144443A1
Application number: PCT/FI2023/050036
Authority: WO
Inventors: Anand Bedekar; Shivanand KADADI
Original assignee: Nokia Technologies Oy
Priority date: 2022-01-26
Filing date: 2023-01-17
Publication date: 2023-08-03

Abstract

A solution for enhancing connection quality is disclosed. The solution comprises obtaining (400) an indication indicative of a handover of a mobile terminal from a source network element to a target network element; receiving (402) from the source network element information related to at least one of channel conditions and transmission parameters used for transmissions between the mobile terminal and the source network element before the handover; determining (404), utilising the received information, one or more transmission attributes to be used for transmissions between the mobile terminal and the target network element after the handover; and indicating (406) to the target network element, the one or more transmission attributes to be used for the transmissions between the mobile terminal and the target network element after the handover.

Description

ENHANCING CONNECTION QUALITY AFTER HANDOVER

Field

The exemplary and non-limiting embodiments of the disclosure relate generally to wireless communication systems. Embodiments of the disclosure relate especially to apparatuses and methods in wireless communication networks.

Background

In wireless telecommunication systems 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.

In cellular communication network with moving terminals, handovers of the terminals from a source cell to a target cell are an integral part of the operation of the network. The number of handovers is expected to increase with the development of 6G network as the density of cells in the network increases. To keep quality of service as high as possible it is advantageous to keep connection quality on a good level after a handover.

Summary

The following presents a simplified summary of the disclosure in order to provide a basic understanding of some aspects of the disclosure. This summary is not an extensive overview of the disclosure. It is not intended to identify key/critical elements of the disclosure or to delineate the scope of the disclosure. Its sole purpose is to present some concepts of the disclosure in a simplified form as a prelude to a more detailed description that is presented later.

According to an aspect of the present disclosure, there is provided an apparatus in a communication system comprising at least one processor; and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus to: obtain an indication indicative of a handover of a mobile terminal from a source network element to a target network element; receive from the source network element information related to at least one of channel conditions and transmission parameters used for transmissions between the mobile terminal and the source network element before the handover; determine, utilising the received information, one or more transmission attributes to be used for transmissions between the mobile terminal and the target network element after the handover; indicate to the target network element, the one or more transmission attributes to be used for the transmissions between the mobile terminal and the target network element after the handover.

According to an aspect of the present disclosure, there is provided a network element in a communication system comprising at least one processor; and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the network element to: determine information related to at least one of channel conditions and transmission parameters used for transmissions between the mobile terminal and the network element; transmit the information to another network apparatus prior to a handover performed by the mobile terminal.

According to an aspect of the present disclosure, there is provided a method in an apparatus of a communication system, comprising: obtaining an indication indicative of a handover of a mobile terminal from a source network element to a target network element; receiving from the source network element information related to at least one of channel conditions and transmission parameters used for transmissions between the mobile terminal and the source network element before the handover; determining, utilising the received information, one or more transmission attributes to be used for transmissions between the mobile terminal and the target network element after the handover; indicating to the target network element, the one or more transmission attributes to be used for the transmissions between the mobile terminal and the target network element after the handover.

According to an aspect of the present disclosure, there is provided a method in a network element of a communication system, comprising: determining information related to at least one of channel conditions and transmission parameters used for transmissions between the mobile terminal and the network element; transmitting the information to another network apparatus prior to a handover performed by the mobile terminal.

According to an aspect of the present disclosure, there is provided a computer program comprising instructions for causing an apparatus to perform at least the following: obtaining an indication indicative of a handover of a mobile terminal from a source network element to a target network element; receiving from the source network element information related to at least one of channel conditions and transmission parameters used for transmissions between the mobile terminal and the source network element before the handover; determining, utilising the received information, one or more transmission attributes to be used for transmissions between the mobile terminal and the target network element after the handover; indicating to the target network element, the one or more transmission attributes to be used for the transmissions between the mobile terminal and the target network element after the handover.

According to an aspect of the present disclosure, there is provided a computer program comprising instructions for causing an apparatus to perform at least the following: determining information related to at least one of channel conditions and transmission parameters used for transmissions between the mobile terminal and the network element; transmitting the information to another network apparatus prior to a handover performed by the mobile terminal.

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 disclosure.

List of drawings

Embodiments of the present disclosure are described below, by way of example only, with reference to the accompanying drawings, in which

Figures 1 and 2 illustrate examples of simplified system architecture of a communication system;

Figures 3A and 3B illustrates situations in a cellular network;

Figures 4 and 5 are flowcharts illustrating embodiments;

Figure 6 is a signalling chart illustrating an embodiment;

Figure 7 is a flowchart illustrating an embodiment; and

Figures 8, 9A and 9B illustrate examples of apparatuses. Description of some embodiments

The following embodiments are only examples. Although the specification may refer to “an”, “one”, or “some” embodiment(s) in several locations, this does not necessarily mean that each such reference is to the same embodiment(s), or that the feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments. Furthermore, words “comprising” and “including” should be understood as not limiting the described embodiments to consist of only those features that have been mentioned and such embodiments may also contain features, structures, units, modules etc. that have not been specifically mentioned.

Some embodiments of the present disclosure are applicable to a user terminal, a communication device, a base station, eNodeB, gNodeB, a distributed realisation of a base station, a network element of a communication system, a corresponding component, and/or to any communication system or any combination of different communication systems that support required functionality.

The protocols used, the specifications of communication systems, servers and user equipment, especially in wireless communication, develop rapidly. Such development may require extra changes to an embodiment. Therefore, all words and expressions should be interpreted broadly and they are intended to illustrate, not to restrict, 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) or new radio (NR, 5G), without restricting the embodiments to such an architecture, however. 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), 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 devices 100 and 102. The devices 100 and 102 are configured to be in a wireless connection on one or more communication channels with a node 104. The node 104 is further connected to a core network 106. In one example, the node 104 may be an access node such as (e/g)NodeB serving devices in a cell. In one example, the node 104 may be a non-3GPP access node. The physical link from a device to a (e/g)NodeB is called uplink or reverse link and the physical link from the (e/g)NodeB to the 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 signalling purposes. The (e/g)NodeB is a computing device configured to control the radio resources of communication system it is coupled to. The 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 devices. The antenna unit may comprise a plurality of antennas or antenna elements. The (e/g)NodeB is further connected to the core network 106 (CN or next generation core NGC). Depending on the deployed technology, the (e/g)NodeB is connected to a serving and packet data network gateway (S-GW +P-GW) or user plane function (UPF), for routing and forwarding user data packets and for providing connectivity of devices to one ore more external packet data networks, and to a mobile management entity (MME) or access mobility management function (AMF), for controlling access and mobility of the devices.

Exemplary embodiments of a device are a subscriber unit, a user device, a user equipment (UE), a user terminal, a terminal device, a mobile station, a mobile device, etc

The device typically refers to a mobile or static device ( e.g. a portable or non-portable computing device) that includes wireless mobile communication devices operating with or without an universal subscriber identification module (USIM), including, but not limited to, the following types of devices: 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 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 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, e.g. to be used in smart power grids and connected vehicles. The device may also utilise cloud. In some applications, a device may comprise a user portable device with radio parts (such as a watch, earphones or eyeglasses) and the computation is carried out in the cloud.

The device 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 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) towards the base station. The device (or in some embodiments a layer 3 relay node) is configured to perform one or more of user equipment functionalities.

Various techniques described herein may also be applied to a cyberphysical system (CPS) (a system of collaborating computational elements controlling physical entities). CPS may enable the implementation and exploitation of massive amounts of interconnected information and communications technology, ICT, 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 cyberphysical 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, many 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 supports 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, e.g. below 6GHz or above 24 GHz, cmWave 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-RI operability (inter-radio interface operability, such as below 6GHz - cmWave, 6 or above 24 GHz - cmWave and 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 substantially 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 multi-access 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 112, such as a public switched telephone network, or a voice over internet protocol (VoIP) network, or the Internet, or a private network, 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.

The technology of Edge cloud may be brought into a radio access network (RAN) by utilizing network function virtualization (NFV) and software defined networking (SDN). Using the technology of 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 or close to a remote antenna site (in a distributed unit, DU 108) and non-real time functions being carried out in a centralized manner (in a centralized unit, CU 110).

It should also be understood that the distribution of labour 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.

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, Mobile Broadband, (MBB) or ensuring service availability for critical communications, and future railway/maritime/aeronautical communications. Satellite communication may utilise 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). At least one satellite 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 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 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 or 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 Fig. 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 needed 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.

Fig.2 illustrates an example of a communication system based on 5G network components. A terminal device, user terminal or user equipment 200 communicating via a 5G network 202 with a data network 112. The user terminal 200 is connected to a Radio Access Network RAN node, such as (e/g)NodeB 206 which provides the user terminal with a connection to the network 112 via one or more User Plane Functions, UPF 208. The user terminal 200 is further connected to Core Access and Mobility Management Function, AMF 210, which is a control plane core connector for (radio) access network and can be seen from this perspective as the 5G version of Mobility Management Entity, MME, in LTE. The 5G network further comprises Session Management Function, SMF 212, which is responsible for subscriber sessions, such as session establishment, modify and release, and a Policy Control Function, PCF 214 which is configured to govern network behavior by providing policy rules to control plane functions. The 5G network may further comprise a location management function, LMF 216, which may be configured to determine the location of the terminal device 200 based on information received from the terminal device and/or gNB 206.

Fig. 3A illustrates a typical situation in a cellular network. A mobile terminal 100 is connected to a network element such as a source gNB 104, but it has been determined that it should make a handover to another network element such as target gNB 300. Handovers are a key part of radio access network, (RAN) operation in cellular networks such as 4G/5G, and mobility scenarios may be even more frequent in the evolution to 6G as the cell size is expected to decrease and density of cells in the network increase. As users with mobile terminals move, handovers are executed in response to the mobility as the user moves from a coverage of one cell to another cell (as in the example of Fig. 3A from the area gNB 104 to the area of gNB 300), or for load-balancing reasons when a user may be handed over from a highly loaded cell to a lightly loaded cell.

In cellular networks such as 4G/5G, when a mobile terminal performs handover from a source cell to a target cell, typically the network element or gNB serving the target cell has very little information about the channel conditions the mobile terminal will have on entering the target cell. Some coarse information is available such as Reference Signal Received Power (RSRP) to the target cell measured by the mobile terminal prior to the handover. RSRP is typically used as one basis for initiating a handover. However, the RSRP may change by the time the handover is done, as handover may complete hundreds of milliseconds after the measurement report was sent by the mobile terminal in the source cell. In addition, RSRP does not relate directly to Signal-to-lnterference-plus-Noise Ratio (SINR), which depends on interference that the mobile terminal would experience in the target cell. Likewise, unknown parameters are fast fading, which is not captured by the RSRP, and beam direction, if the target cell uses beamforming, which is likely in the developing networks.

As the target gNB has no accurate information about channel conditions regarding the mobile terminal in the target cell, the target gNB is forced to start transmission to the mobile terminal using transmission parameters, which may be sub-optimal. In the absence of any such accurate information, typically the target gNB may start with just default values for transmission parameters, for example, a default modulation and coding scheme, which are typically set in the substantially same static way for some or all users performing handover regardless of actual channel conditions. The target gNB has to ensure that the mobile terminal can communicate even in a worst-case situation, and so may have to ensure that these default starting transmission parameters can support some expected worst-case or typical scenario. For example, the target gNB may not have any Channel Quality Indicator (CQI) feedback from the mobile terminal, and hence start with a modulation and coding scheme (MCS) which may be too conservative if the interference experienced by the mobile terminal is low, or may be too aggressive if the interference experienced by the mobile terminal is high, depending on how the default MCS is set.

Further, the target gNB may not have any feedback on suitable precoder or channel rank to use for the mobile terminal, and so may have to use some default beamforming parameters, leading to a misdirected beam and loss of beamforming gain, or loss of rank. In addition, the target gNB is not aware of which Secondary Cells (SCells) may be suitable to add for the mobile terminal for carrier aggregation after handover to the target cell, and so be unable to add/activate Scells, leading to loss of potential throughput that could be delivered by Scells after the handover. Moreover, on the uplink the target gNB will not know any suitable beamforming or pathloss information and is therefore forced to use a conservative MCS and/or a too low number of physical resource blocks (PRBs) and/or a wide-angle or misdirected receive beam, leading to loss of spectral efficiency and throughput.

Therefore, after the handover, it may be possible that the mobile terminal will suffer a temporary drop in throughput compared to its throughput prior to the handover. Thus, even though the mobile terminal may be executing a handover to the target cell that should be theoretically better for it than the source cell, in practice the mobile terminal may actually experience a temporary loss of throughput. This situation may persist until the mobile terminal can actually start sending channel state related information in the target gNB, a process which can take hundreds of milliseconds after the handover is complete. For example, after the handover the target gNB would have to configure the mobile terminal with suitable control channel resources for reporting channel state feedback (such as time/frequency resources on PUCCH), and then have the UE monitor for reference signals such as channel state information reference signals (CSI-RS), subsequent to which the UE can then start reporting some channel state feedback on its assigned time/frequency resources on PUCCH. Typically, only after this sequence of actions is completed would the target gNB be able to determine appropriate transmission attributes for the mobile terminal in the target cell. This sequence can take well over a hundred milliseconds after the completion of the handover, depending on the target gNB’s configuration and loading, during which time the mobile terminal would experience loss of throughput. The transmission attributes may comprise various transmission parameters such as modulation order, code rate, amount of resource allocation, beamforming parameters, and timing advance, etc.

What the inventors have noticed is that the history of channel measurements for the mobile terminal relative to the source cell as well as information about previous transmissions from the source cell to the mobile terminal are available prior to the handover at the gNB serving the source cell. This information can be used to predict channel conditions in the target cell, and thus the information can be used to determine a recommendation of transmission parameters to be used at target gNB after the handover. In an embodiment, the source cell is configured to transmit data related to mobile terminal connection to an apparatus, a Post-Handover Transmission Attributes Recommender (PHTAR), which is configured to determine a recommendation of suitable transmission parameters for the mobile terminal in the target cell after handover, based at least in part on the channel measurements and transmission history of the mobile terminal in the source cell prior to the handover.

In the example of Fig 3A, the PHTAR is a separate entity 302 connected to the gNBs via an E2 interface. In the example of Fig 3B, the PHTAR 302 is a part of the target gNB and the source gNB may transmit needed data to the PHTAR via Xn or X2 interface, for example.

Fig. 4 is a flowchart illustrating an embodiment. The flowchart illustrates an example of the operation of an apparatus. In an embodiment, the apparatus may be a Post-Handover Transmission Attributes Recommender (PHTAR), located in a gNB or as a separate entity or a part of another network element.

In step 400, the apparatus is configured to obtain an indication indicative of a handover a mobile terminal is to perform from a source network element or source gNB to a target network element or target gNB. The source gNB and target gNB may have negotiated the handover of the mobile terminal.

In step 402, the apparatus is configured to receive from the source network element or source gNB information related to at least one of channel conditions and transmission parameters used for transmissions between the mobile terminal and the source network element or source gNB before the handover.

In step 404, the apparatus is configured to determine, utilising the received nformation, one or more transmission attributes to be used for transmission between the target network element or target gNB and the mobile terminal after the handover.

In an embodiment, the one or more transmission attributes between the target gNB and the mobile terminal for which the recommendation is made may include, for example, a downlink and/or uplink modulation and coding scheme (MCS), beamforming-related parameters such as digital or analog or hybrid beamforming parameters, precoding matrix, rank of transmission, number of layers, indication of number of demodulation reference signal (DMRS) symbols to use, aggregation level for Physical Downlink Control Channel (PDCCH) transmissions, and power control parameters for uplink transmissions. It may also include indication of whether carrier aggregation should be configured for the mobile terminal after handover (and if so, indication of which Scells can be selected, and similar transmission parameters to be used in Scells after the handover).

In step 406, the apparatus is configured to indicate to the target network element or target gNB the one or more transmission attributes to be used for the transmissions between the mobile terminal and the target network element after the handover.

Fig. 5 is a flowchart illustrating an embodiment. The flowchart illustrates an example of the operation of a network element apparatus. In an embodiment, the apparatus may be the source gNB or a part of the source gNB.

In step 500, the apparatus is configured to determine information related to at least one of channel conditions and transmission parameters used for transmissions between the mobile terminal and the network element;

In step 504, the apparatus is configured to transmit the information to another network apparatus. The other network element may be the PHTAR, for example.

In an embodiment, the information is encoded before transmission.

Fig. 6 is a signalling chart illustrating an embodiment. The chart illustrates an example of message flow between the source gNB 104, target gNB 300, the PHTAR 302, neighbouring gNBs 600 and the mobile terminal 100 during a situation where the mobile terminal 100 is about to make a handover.

The source gNB 104 and target gNB are configured to negotiate 602 to decide to perform a handover of the mobile terminal 100 from the source gNB 104 to the target gNB 300.

This procedure may as such be performed via similar mechanisms as in present 4G systems (with X2 interaction) or in 5G systems (with Xn interaction). The handover may be initiated based on various criteria, e.g. when for example the mobile terminal 100 reports a measurement event indicating that signal strength from the source cell served by the source gNB has become weak, or signal strength of the target cell served by the target gNB has become sufficiently strong relative to signal strength of source cell, or for example when the load in the source cell served by the source gNB has increased to a high level compared to the target cell served by the target gNB due to which it would become advantageous to hand over the UE to the target cell. The way the handover as such is performed as in present 4G or 5G networks, for example by the mobile terminal receiving a Radio Resource Control (RRC) handover command from the source gNB, then attempting a Random Access Channel (RACH) and RRC connection establishment for the target gNB), or based on L1/L2 methods planned to be introduced in later developments of these networks.

In an embodiment, the handover may be also a soft or softer handover, where the connection to the source gNB is not terminated until the transmission from the target gNB is successfully established, or a hard handover where the connection from the source gNB is first terminated and then the connection to the target gNB is attempted by the mobile terminal.

Embodiments of the disclosure may be applied regardless how the handover is performed.

If it was negotiated that a handover will be made, the source gNB is configured to determine 604 information to be transmitted to the target gNB. In an embodiment, the source gNB is configured to determine encoding to be used in the transmission.

The source gNB 104, on an ongoing basis, may be configured to store in its memory a sequence of N most recent channel measurements for the mobile terminal, where N is a parameter which can be chosen in a suitable manner.

In an embodiment, the channel measurements may have been either measured by the mobile terminal and reported to the source gNB or measured by the source gNB, or quantities derived from such measurements.

In an embodiment, the measurements made by the mobile terminal may be related to CQI, Rank Indicator (Rl), Pre-coding Matrix Indicator (PMI), Channel State Information Reference Signal Resource Indicator (CRI), beam measurements such as synchronization signal block (SSB) beam measurements, Power Headroom Report (PHR), or RSRP or Received Signal / Reference Signal Received Quality (RSRQ) measurements relative to source gNB and/or other gNBs, or measurements related to UE positioning or location such as observed time difference of arrival of positioning or other reference signals, for example. In addition, certain parameters that were used by the gNB to facilitate the measurements by the mobile terminal may also be taken into account, such as beamforming used for channel state information reference signals, or beam parameters of SSB beams, or power offsets for sending reference signals, or the like.

In an embodiment, the measurements made by the source gNB may be related to Sounding Reference Signal (SRS) or interference information. The measurements may also relate to received signal information of demodulation reference signal (DMRS), Physical Uplink Control Channel (PUCCH) or Physical Uplink Shared Channel transmission. The measurements may also relate to quantities derived from above measurements e.g. spectral efficiency corresponding to the CQI+RI, or The measurements may also be eigenvectors based on channel covariance matrix derived from the SRS measurements, or timing advance derived from uplink transmissions such as RACH or PUCCH, for example.

In an embodiment, not only measurements related to the source cell, but also mobile terminal measurements relative to neighbour cells of the source or target cell that are reported to the source cell, such as RSRP or path loss of signal from neighbour cells may be taken into account. In an embodiment, if the mobile terminal is in carrier aggregation while connected to the source cell, then measurements for the mobile terminal relative to the secondary cells (Scells) may also be taken into account.

In an embodiment, it may be useful to include information such as SRS that can capture directionality of the signal path to the mobile terminal. When the gNB and mobile terminal have multiple antennas (as likely in 5G and later systems), this information is more valuable in determining some aspects of the transmission attributes to be used after the handover. The greater the number of more the antennas (for massive MIMO, for example), the more valuable such information is that captures directionality.

The source gNB 104, on an ongoing basis, may be configured to store in its memory recent transmission information of the mobile terminal.

In an embodiment, the transmission information may comprise a sequence of MCS used for downlink or uplink transmission, aggregation level used to transmit on Physical Downlink Control Channel (PDCCH), link adaptation correction factors used by the gNB to determine the achievable MCS or spectral efficiency on Physical Downlink Shared Channel (PDSCH), PUSCH or PDCCH, power control offsets to be used for the mobile terminal, or hybrid automatic repeat request (HARQ) status (e.g. ack or nack) of various transmissions, for example, beamforming parameters used for transmission to the UE such as digital or analog or hybrid beamforming parameters, precoding matrices, rank or number of layers, aggregation levels used for PDCCH transmissions, carrier frequency and bandwidth, timing advance, measurements of signals received from the mobile terminal, angle of arrival of signal received from the mobile terminal, and location information about the mobile terminal, channel covariance matrix, or eigenvectors derived from channel covariance matrix and the like .

In an embodiment, in order to determine the encoding, the source gNB may use these sequences of measurements and transmission information of the mobile terminal at source gNB prior to the handover.

Thus, the measurements and transmission information considered here are for measurements and transmissions made in the source cell prior to the execution of the handover. In an embodiment, the time at which the determination of the encoding is made may vary. It may be as soon as it is decided to perform the handover, or some time (20ms, for example) after the decision is made. In an embodiment, the determination of the encoding may happen even before the decision is made so that the source gNB can reduce the latency of a possible handover by performing the determination in anticipation of the handover.

The determination of the encoding can be done in a variety of ways. In an embodiment, artificial intelligence or machine learning (AI/ML) technique such as autoencoder may be used. The sequence of measurements and transmission information can be treated as an input vector in a high-dimensional space. In an embodiment, the input vector may be normalized to make the magnitude of values in the different dimensions of the input vector commensurate to each other so as to reduce numerical distortions, for example by subtracting from at least one component of the input vector a mean value and dividing by a standard deviation of the component, where the mean and standard deviation are calculated over multiple samples (possibly corresponding to handovers by different mobile terminals, but preferably between the substantially same source cell and target cell).

An auto-encoder is typically a machine learning model or a neural network that can be trained to generate an encoding of the input vector, such that a corresponding decoding generated from the encoding (typically by using another neural network with different weights than the one used to generate the encoding) minimizes an error metric (such as a squared error) relative to the input vector, over the set of training input vectors.

In an embodiment, instead of an auto-encoder, other techniques may as well be used, such as vector quantization, or dimensionality reduction, or embeddings, or principal component analysis.

Typically, this encoding will be represented in a quantized form by a certain number of bits or as an integer or as a floating point number or vector. The auto-encoder may directly generate the quantized form, or may generate a real valued number or vector that can then be quantized separately

In an embodiment, the “size of the encoding” (the number of dimensions, or the number of bits used to represent the encoding, for example) can be chosen during training of the auto encoder, so that the generated encoding size is small enough while keeping the error metric to acceptable levels.

After the encoding has been performed, the source gNB is configured to transmit 606 the encoded data to the PHTAR 302. If PHTAR 302 is a separate unit, it would receive the encoding from source gNB over the E2 interface. If PHTAR 302 is situated at the target gNB, it would receive the encoding from the source gNB typically over the X2 or Xn interface in case of 4G or 5G networks.

In an embodiment, the PHTAR 302 may be configured to receive 608 from the target network element and/or other network elements geographic information such as, for example, location information and orientation information, of the transmission points of the source and target network elements and interfering information on network elements interfering the source and target network elements. This received geographic information may be taken into account when determining one or more transmission attributes based on at least one of the geographic information and the interfering information.

In addition to the information received from the source gNB 104, the PHTAR 302 may receive certain information about the source and target cells, in order to improve the recommendation of transmission parameters for the mobile terminal in the target cell after the handover.

The additional information may comprise location and orientation of the transceivers, antennas or sectors in the source and target cells, and optionally, for neighbor cells of the source and target cells. This information is relatively static or may not be specific to a transmission of any particular mobile terminal and may be received infrequently or only once.

In an embodiment, additional information may comprise activity factor and beam pattern information of the neighbour cells whose transmissions interfere with the source cell and/or target cell. This information may change over time, and may be received periodically by the PHTAR, either from the source and target cells, or directly from the neighbour cells (over X2/Xn interfaces, for example).

In an embodiment, the additional information may also include information from target gNB immediately after the handover, for example information about the RACH connection or RRC connection attempt made by the mobile terminal after the handover or values derived therefrom. For example, the target gNB may send to the PHTAR a timing advance value derived from the RACH attempt or identity/direction or other parameters of a beam, such as an SSB beam, corresponding to the RACH made by the mobile terminal.

Utilising the received information, the PHTAR is configured to determine 610 one or more transmission attributes or recommendation for the one or more transmission attributes for the connection between the target gNB 300 and the mobile terminal 100.

In an embodiment, PHTAR may be configured to utilise artificial intelligence or machine learning such as a trained neural network in determining the one or more transmission attributes.

In an embodiment, the input to the trained neural network may be a vector comprising of the encoding of the sequence of measurements and one or more transmission attributes in the source gNB prior to the handover, optionally along with the additional information 608.

In an embodiment, other prediction techniques such as a support-vector machine (SVM) may be used.

In an embodiment, the timing of the determination of the one or more transmission attributes can be selectable.

In an embodiment, the determination may be made prior to the connection attempt of the mobile terminal in the target cell. In such a case the PHTAR would not be able to use any information about the mobile terminal’s connection attempt or RACH in the target cell such as timing advance.

In another embodiment, the determination may be made by the PHTAR after the mobile terminal has started its connection attempt. This would allow the PHTAR to use for example the timing advance of the mobile terminal in the target cell after handover. However, a low latency may be needed for any communication between PHTAR and the target cell so that the recommendation of the transmission attributes from PHTAR can be received and used by the target cell expeditiously after handover.

In an embodiment, when the PHTAR is located at the target gNB, the latter alternative may be used and when PHTAR is a separate element, the former alternative may be used. However, other possibilities exist as well.

When a recommendation of the transmission attributes has been determined, the PHTAR 302 may provide 302 the recommendation to the target gNB 300. If the PHTAR is as separate element this can happen over E2 interface. If the PHTAR is at target gNB, then this communication would be internal to the target gNB.

The target gNB 300 may then use 614 the recommended transmission attributes to start transmitting to the mobile terminal 100 after the handover.

As it can safely be assumed that the recommended transmission attributes will be close to what is best for the mobile terminal 100, the target gNB 300 can rapidly reach the best transmission attributes by starting with the recommendation of the PHTAR and then if needed fine-tuning by small adjustments. This will minimize any throughput loss that would have been suffered by the mobile terminal if the target gNB had instead started with default transmission attributes after the handover.

Fig. 7 is a flowchart illustrating an embodiment. The flowchart illustrates an example of training of the neural network utilised by the PHTAR when determining the transmission parameters.

In step 700, the PHTAR is configured to collect data. The PHTAR 302 and the target gNB 300 may enter a data collection phase, where the PHTAR does not provide any recommendation of transmission attributes, but the target gNB can use a conventional algorithm to start from a default value of transmission attributes and gradually adapt them by observing the CSI reported by a mobile terminal and sequence of acknowledgements and negative acknowledgements (ACK/NACK) to eventually achieve suitable transmission attributes. In an embodiment, the PHTAR is configured to collect transmission attributes data related to a connection between a mobile terminal and the target network element wherein the transmission attribute data relates to transmissions between one or more mobile terminals and the target network element after performing handovers of the one or more mobile terminals from the source network element to the target network element.

In an embodiment, the PHTAR is further configured to collect encoded data related to channel conditions and data related to transmission attributes on a connection between the one or more mobile terminals and the source network element prior to performing handovers of the one or more mobile terminal to the target network element.

In step 702, the PHTAR is configured to store data as training data. The PHTAR may store the transmission attributes reached by the target gNB using a conventional algorithm after a period of time (such as 500ms, for example), along with encoding and additional information, into a training data set. The transmission attributes thus achieved by the conventional algorithm would represent the ideal desired output corresponding to that encoding vector and the additional information vector.

In step 704, the PHTAR apparatus is configured to train neural network and continue collecting data. Over time (for example over a number of handovers over a day or a few days), the PHTAR may then accumulate enough training data to train an initial neural network to produce an initial recommendation of transmission attributes. For subsequent handovers over a further time period (another few days, for example), the PHTAR may use this initial neural network to determine recommendations and provide them to the target gNB, which then starts using these recommended transmission attributes to start transmission to mobile terminals after handover. In an embodiment, the target gNB can further continue to use its conventional adaptation algorithms to further refine the transmission attributes based on the actual reported CSI and the observed ACK/NACKs after handover, to reach a new eventual transmission attributes for the mobile terminal (for example after 500ms after the handover). These eventual attributes may again be reported to the PHTAR.

In step 706, the PHTAR apparatus is configured to receive the data and added the data to the training set and update the neural network after sufficient such new data has been collected.

In an embodiment, the training process may be repeated periodically, or when it is observed that the eventual transmission attributes reached after handover diverge significantly from the recommendations of the PHTAR.

Fig. 8 illustrates an embodiment. The figure illustrates a simplified example of an apparatus applying embodiments of the disclosure. In some embodiments, the apparatus may be a network element acting as a Post-Handover Transmission Attributes Recommender (PHTAR) 302, which is configured to determine a recommendation of suitable transmission attributes for the mobile terminal in the target cell after handover, based at least in part on the channel measurements and transmission history of the mobile terminal in the source cell prior to the handover.

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

The apparatus 302 of the example includes a control circuitry 800 configured to control at least part of the operation of the apparatus.

The apparatus may comprise a memory 802 for storing data. Furthermore, the memory may store software 804 executable by the control circuitry 800. The memory may be integrated in the control circuitry.

The apparatus may comprise one or more interface circuitries 806. The interface circuitries are operationally connected to the control circuitry 800. The one or more interface circuitries 806 may connect the apparatus to other network elements in a wired or wireless manner, for example utilising an E2 interface.

In an embodiment, the software 804 may comprise a computer program comprising program code means configured to cause the control circuitry 800 of the apparatus to realise at least some of the embodiments described above.

Fig. 9A illustrates an embodiment. The figure illustrates a simplified example of a network element applying embodiments of the disclosure. In some embodiments, the network element may be a gNB 104, 300, or a part of a terminal device of a telecommunication system. It should be understood that the network element is depicted herein as an example illustrating some embodiments. It is apparent to a person skilled in the art that the network element may also comprise other functions and/or structures and not all described functions and structures are required. Although the network element has been depicted as one entity, different modules and memory may be implemented in one or more physical or logical entities.

The network element 104, 300 of the example includes a control circuitry 900 configured to control at least part of the operation of the network element.

The network element may comprise a memory 902 for storing data. Furthermore, the memory may store software 904 executable by the control circuitry 900. The memory may be integrated in the control circuitry.

The network element may comprise one or more interface circuitries 906, 908. The interface circuitries are operationally connected to the control circuitry 900. An interface circuitry 906 may be a set of transceivers configured to communicate with a RAN node, such as an (e/g)NodeB of a wireless communication network. The interface circuitry may be connected to an antenna arrangement (not shown). The network element may also comprise a connection to a transmitter instead of a transceiver.

An interface circuitry 908 may connect the apparatus to other network elements in a wired or wireless manner, for example utilising an E2, X2 or Xn interface.

In an embodiment, the software 904 may comprise a computer program comprising program code means configured to cause the control circuitry 900 of the network element to realise at least some of the embodiments described above.

If the network element of Fig. 9A is the target gNB 302, it may further comprise a Post-Handover Transmission Attributes Recommender (PHTAR) 302.

In an embodiment, as shown in Fig. 9B, at least some of the functionalities of the apparatus of Fig. 9B 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. 9B, utilizing such shared architecture, may comprise a remote control unit RCU 920, such as a host computer or a server computer, operatively coupled (e.g. via a wireless or wired network) to a remote distributed unit RDU 922 located in the base station. In an embodiment, at least some of the described processes may be performed by the RCU 920. In an embodiment, the execution of at least some of the described processes may be shared among the RDU 922 and the RCU 920.

In an embodiment, the RCU 920 may generate a virtual network through which the RCU 920 communicates with the RDU 922. 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 RDU and the RCU. In practice, any digital signal processing task may be performed in either the RDU or the RCU and the boundary where the responsibility is shifted between the RDU 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, processing system or a circuitry which may comprise a working memory (random access 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 processing system, controller or the circuitry 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.

An embodiment provides an apparatus comprising means for obtaining an indication indicative of a handover of a mobile terminal from a source network element to a target network element; means for receiving from the source network element information related to at least one of channel conditions and transmission parameters used for transmissions between the mobile terminal and the source network element before the handover; means for determining, utilising the received information, one or more transmission attributes to be used for transmissions between the mobile terminal and the target network element after the handover; and means for indicating to the target network element, the one or more transmission attributes to be used for the transmissions between the mobile terminal and the target network element after the handover. An embodiment provides an apparatus comprising means for determining information related to at least one of channel conditions and transmission parameters used for transmissions between the mobile terminal and the network element and means for transmit the information to another network apparatus.

An embodiment provides a computer program embodied on a distribution medium, comprising program instructions which, when loaded into an electronic apparatus, are configured to control the apparatus to execute at least the following: obtaining an indication indicative of a handover of a mobile terminal from a source network element to a target network element; means for receiving from the source network element information related to at least one of channel conditions and transmission parameters used for transmissions between the mobile terminal and the source network element before the handover; means for determining, utilising the received information, one or more transmission attributes to be used for transmissions between the mobile terminal and the target network element after the handover; and means for indicating to the target network element, the one or more transmission attributes to be used for the transmissions between the mobile terminal and the target network element after the handover.

An embodiment provides a computer program embodied on a distribution medium, comprising program instructions which, when loaded into an electronic apparatus, are configured to control the apparatus to execute at least the following: determining information related to at least one of channel conditions and transmission parameters used for transmissions between the mobile terminal and the network element and means for transmit the information to another network apparatus.

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 several 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.

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 disclosure and its embodiments are not limited to the examples described above but may vary within the scope of the claims.

List of Abbreviations:

ACK acknowledgement AI/ML artificial intelligence or machine learning AMF access mobility management function ASIC application-specific integrated circuits CN core network CPS cyber-physical system CPU central processing unit CQI channel quality indicator CRI CSI Reference Signal Resource Indicator CSI channel state information CSI-RS channel state information reference signal CU centralized unit DMRS demodulation reference signal DU distributed unit GEO geostationary earth orbit HARQ hybrid automatic repeat request HNB home nodeB HNB-GW HNB gateway ICT information and communications technology IMS Internet Protocol multimedia subsystems loT internet of things LEO low earth orbit LTA-A long term evolution advanced M2M machine-to-machine MANET mobile ad-hoc networks MBB mobile broadband MCS modulation and coding scheme MEC multi-access edge computing MIMO multiple input - multiple output MMF mobile management entity mMTC massive machine-type communications NACK negative acknowledgement NFV network function virtualization NGC next generation core NR, 5G new radio PCF policy control function PCS personal communications services PDA personal digital assistant PDCCH physical downlink control channel PDSCH physical downlink shared channel PHR power headroom report PHTAR post-handover transmission attributes recommender PMI pre-coding matrix indicator PRB physical resource blocks PUCCH physical uplink control channel RACH random access channel RAM random access memory RAN radio access network RCU remote control unit RDU remote distributed unit Rl rank indicator RRC radio resource control RSRP reference signal received power RSRQ reference signal received quality SCell secondary cell SDN software defined networking S-GW+P-GW serving and packet data network gateway

SINR signal-to-interference-plus-noise ratio

SMF session management function

SRS sounding reference signal SSB synchronization signal block

SVM support-vector machine

UE user equipment

UMTS universal mobile telecommunications system

UPF user plane function USIM universal subscriber identification module

UTRAN UMTS radio access network

UWB ultra-wideband

VoIP voice over internet protocol

WCDMA wideband code division multiple access WiMAX worldwide interoperability for microwave access

WLAN, WIFI wireless local area network

Claims

1. An apparatus in a communication system comprising at least one processor; and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus to: obtain an indication indicative of a handover of a mobile terminal from a source network element to a target network element; receive from the source network element information related to at least one of channel conditions and transmission parameters used for transmissions between the mobile terminal and the source network element before the handover; determine, utilising the received information, one or more transmission attributes to be used for transmissions between the mobile terminal and the target network element after the handover; indicate to the target network element, the one or more transmission attributes to be used for the transmissions between the mobile terminal and the target network element after the handover.

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: receive from the target network element and/or other network elements, geographic information of one or more transmission points of the source and target network elements and interfering information on network elements interfering the source and target network elements; determine the one or more transmission attributes based on at least one of the geographic information and the interfering information.

3. The apparatus of any preceding claim, wherein the information received from the source network element is encoded, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus further to decode the encoded information.

4. The apparatus of any preceding claim, wherein the one or more transmission attributes comprise one or more of the following: modulation and coding scheme, beamforming parameters, number of physical resource blocks, timing advance.

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 utilise a trained machine learning model in determining the one or more transmission attributes.

6. The apparatus of any preceding claim, wherein the information received from the source network element comprise one or more of the following: information related to channel measurements made by the mobile terminal regarding the source network element and other neighbouring network elements, modulation and coding scheme used on uplink and/or downlink connection between the mobile terminal and the source network element, link adaptation correction factors, power control offsets, hybrid automatic repeat request status.

7. The apparatus of any preceding claim, wherein the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus further to: collect information related to at least one of channel conditions and transmission parameters used for transmissions between one or more mobile terminals and the target network element wherein the information relates to transmissions between one or more mobile terminals and the target network element after performing handovers of the one or more mobile terminals from the source network element to the target network element; collect encoded information related to at least one of channel conditions and transmission parameters used for transmissions between the one or more mobile terminals and the source network element prior to performing handovers of the one or more mobile terminal to the target network element; store the collected information as training data; train or update a machine learning model or a neural network with the training data wherein the machine learning model or neural network is configured to take as input an encoding of data related to channel conditions and transmission parameters of a mobile terminal prior to its handover from the source network element to the target element, and to produce as output a recommendation of the transmission parameters for the mobile terminal in the target network element after the handover.

8. A network element in a communication system comprising at least one processor; and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the network element to: determine information related to at least one of channel conditions and transmission parameters used for transmissions between the mobile terminal and the network element; transmit the information to another network apparatus prior to a handover performed by the mobile terminal.

9. The network element of claim 8, wherein the information transmitted to the another network apparatus comprise one or more of the following: information related to channel measurements made by the mobile terminal regarding the network element and other neighbouring network elements and reported by the mobile terminal to the network element, modulation and coding scheme used on uplink and/or downlink connection between the mobile terminal and the network element, channel quality indicator, link adaptation correction factors, power control offsets power headroom report, hybrid automatic repeat request status, beamforming parameters, carrier frequency and bandwidth, timing advance, measurements of signals received from the mobile terminal, angle of arrival of signal received from the mobile terminal, and location information about the mobile terminal, channel covariance matrix, or eigenvectors derived from channel covariance matrix.

10. The network element of claim 8 or 9, the at least one memory and the computer program code configured to, with the at least one processor, cause the network element further to encode the information using a trained autoencoder.

11 . A method in an apparatus of a communication system, comprising: obtaining an indication indicative of a handover of a mobile terminal from a source network element to a target network element; receiving from the source network element information related to at least one of channel conditions and transmission parameters used for transmissions between the mobile terminal and the source network element before the handover; determining, utilising the received information, one or more transmission attributes to be used for transmissions between the mobile terminal and the target network element after the handover; indicating to the target network element, the one or more transmission attributes to be used for the transmissions between the mobile terminal and the target network element after the handover.

12. The method of claim 11 , further comprising: receiving from the target network element and/or other network elements, geographic information of transmission points of the source and target network elements and interfering information on network elements interfering the source and target network elements; determine the one or more transmission attributes based on at least one of the geographic information and the interfering information.

13. The method of claim 11 or 12, wherein the one or more transmission attributes comprise one or more of the following: modulation and coding scheme, beamforming parameters, number of physical resource blocks, timing advance.

14. The method of claim 11 or 12, further comprising: collecting information related to at least one of channel conditions and transmission parameters used for transmissions between one or more mobile terminals and the target network element wherein the information relates to transmissions between the one or more mobile terminals and the target network element after a handover the one or more mobile terminals from the source network element to the target network element; collecting encoded information related to at least one of channel conditions and transmission parameters used for transmissions between the one or more mobile terminals and the source network element prior to the handover; storing the collected information as training data; training or updating a machine learning model or a neural network with the training data wherein the machine learning model or neural network is configured to take as input an encoding of data related to channel conditions and transmission parameters of one of the one or more mobile terminals prior to its handover from the source network element to the target element, and to produce as output a recommendation of the transmission parameters for the one of the one or more mobile terminals in the target network element after the handover.

15. A method in a network element of a communication system, comprising: determining information related to at least one of channel conditions and transmission parameters used for transmissions between a mobile terminal and the network element; transmitting the information to another network element prior to a handover performed by the mobile terminal.

16. The method of claim 15, wherein the information transmitted to the another network element comprises one or more of the following: information related to channel measurements made by the mobile terminal regarding the network element and one or more other neighbouring network elements and reported by the mobile terminal to the network element, modulation and coding scheme used on uplink and/or downlink connection between the mobile terminal and the network element, channel quality indicator, link adaptation correction factors, power control offsets power headroom report, hybrid automatic repeat request status, beamforming parameters, carrier frequency and bandwidth, timing advance, measurements of signals received from the mobile terminal, angle of arrival of signal received from the mobile terminal, and location information about the mobile terminal, channel covariance matrix, or eigenvectors derived from channel covariance matrix.

17. A computer program comprising instructions for causing an apparatus to perform at least the following: obtaining an indication indicative of a handover of a mobile terminal from a source network element to a target network element; receiving from the source network element information related to at least one of channel conditions and transmission parameters used for transmissions between the mobile terminal and the source network element before the handover; determining, utilising the received information, one or more transmission attributes to be used for transmissions between the mobile terminal and the target network element after the handover; indicating to the target network element, the one or more transmission attributes to be used for the transmissions between the mobile terminal and the target network element after the handover.

18. A computer program comprising instructions for causing a network element to perform at least the following: determining information related to at least one of channel conditions and transmission parameters used for transmissions between a mobile terminal and the network element; transmitting the information to another network element prior to a handover performed by the mobile terminal.

19. An apparatus in a communication system comprising means for: obtaining an indication indicative of a handover of a mobile terminal from a source network element to a target network element; receiving from the source network element information related to at least one of channel conditions and transmission parameters used for transmissions between the mobile terminal and the source network element before the handover; determining, utilising the received information, one or more transmission attributes to be used for transmissions between the mobile terminal and the target network element after the handover; indicating to the target network element, the one or more transmission attributes to be used for the transmissions between the mobile terminal and the target network element after the handover.

20. A network element in a communication system comprising means for: determining information related to at least one of channel conditions and transmission parameters used for transmissions between the mobile terminal and the network element; transmitting the information to another network apparatus prior to a handover performed by the mobile terminal.