WO2023198289A1

WO2023198289A1 - Signalling for coded caching

Info

Publication number: WO2023198289A1
Application number: PCT/EP2022/060018
Authority: WO
Inventors: Kari Juhani Hooli; Mohammad Javad SALEHI; Antti Tölli
Original assignee: Nokia Technologies Oy
Priority date: 2022-04-14
Filing date: 2022-04-14
Publication date: 2023-10-19

Abstract

Disclosed is a method comprising transmitting, to one or more user devices, a first set of data comprising at least one subpacket of at least one file of a set of files; transmitting, to the one or more user devices, a set of identifiers and a mapping indicating an association of the set of identifiers to a subset of subpackets of the set of files; transmitting, to the one or more user devices, an indication for determining one or more identifiers associated with a second set of data to be transmitted over a plurality of overlapping data channels, wherein the one or more identifiers are comprised in the set of identifiers, and the second set of data comprises at least a part of one or more subpackets of the subset of subpackets; and transmitting, to the one or more user devices, the plurality of overlapping data channels.

Description

SIGNALLING FORCODEDCACHING FIELD The following example embodiments relate to wireless communication. BACKGROUND Coded caching may be used to increase the available data rate of communication links with the help of storage space available on communication devices. As resources are limited, it is desirable to reduce the signalling overhead associated with coded caching. BRIEF DESCRIPTION The scope of protection sought for various example embodiments is set out by the independent claims. The example embodiments 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. According to an aspect, there is provided an apparatus comprising at least one processor, and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to: receive a first set of data, wherein the first set of data comprises at least one subpacket of at least one file of a set of files; receive a set of identifiers and a mapping indicating an association of the set of identifiers to a subset of subpackets of the set of files; receive an indication for determining one or more identifiers associated with a second set of data to be transmitted over a plurality of overlapping data channels, wherein the one or more identifiers are comprised in the set of identifiers, and the second set of data comprises at least a part of one or more subpackets of the subset of subpackets; identify one or more data channels to be cancelled from the plurality of overlapping data channels, wherein the one or more data channels are identified based at least partly on the one or more identifiers; receive the plurality of overlapping data channels, wherein the plurality of overlapping data channels overlap in time and frequency; and cancel the one or more data channels of the plurality of overlapping data channels based at least partly on the first set of data. According to another aspect, there is provided an apparatus comprising means for: receiving a first set of data, wherein the first set of data comprises at least one subpacket of at least one file of a set of files; receiving a set of identifiers and a mapping indicating an association of the set of identifiers to a subset of subpackets of the set of files; receiving an indication for determining one or more identifiers associated with a second set of data to be transmitted over a plurality of overlapping data channels, wherein the one or more identifiers are comprised in the set of identifiers, and the second set of data comprises at least a part of one or more subpackets of the subset of subpackets; identifying one or more data channels to be cancelled from the plurality of overlapping data channels, wherein the one or more data channels are identified based at least partly on the one or more identifiers; receiving the plurality of overlapping data channels, wherein the plurality of overlapping data channels overlap in time and frequency; and cancelling the one or more data channels of the plurality of overlapping data channels based at least partly on the first set of data.

According to another aspect, there is provided a method comprising: receiving a first set of data, wherein the first set of data comprises at least one subpacket of at least one file of a set of files; receiving a set of identifiers and a mapping indicating an association of the set of identifiers to a subset of subpackets of the set of files; receiving an indication for determining one or more identifiers associated with a second set of data to be transmitted over a plurality of overlapping data channels, wherein the one or more identifiers are comprised in the set of identifiers, and the second set of data comprises at least a part of one or more subpackets of the subset of subpackets; identifying one or more data channels to be cancelled from the plurality of overlapping data channels, wherein the one or more data channels are identified based at least partly on the one or more identifiers; receiving the plurality of overlapping data channels, wherein the plurality of overlapping data channels overlap in time and frequency; and cancelling the one or more data channels of the plurality of overlapping data channels based at least partly on the first set of data.

According to another aspect, there is provided a computer program comprising instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: receiving a first set of data, wherein the first set of data comprises at least one subpacket of at least one file of a set of files; receiving a set of identifiers and a mapping indicating an association of the set of identifiers to a subset of subpackets of the set of files; receiving an indication for determining one or more identifiers associated with a second set of data to be transmitted over a plurality of overlapping data channels, wherein the one or more identifiers are comprised in the set of identifiers, and the second set of data comprises at least a part of one or more subpackets of the subset of subpackets; identifying one or more data channels to be cancelled from the plurality of overlapping data channels, wherein the one or more data channels are identified based at least partly on the one or more identifiers; receiving the plurality of overlapping data channels, wherein the plurality of overlapping data channels overlap in time and frequency; and cancelling the one or more data channels of the plurality of overlapping data channels based at least partly on the first set of data.

According to another aspect, there is provided a computer program comprising instructions for causing an apparatus to perform at least the following: receiving a first set of data, wherein the first set of data comprises at least one subpacket of at least one file of a set of files; receiving a set of identifiers and a mapping indicating an association of the set of identifiers to a subset of subpackets of the set of files; receiving an indication for determining one or more identifiers associated with a second set of data to be transmitted over a plurality of overlapping data channels, wherein the one or more identifiers are comprised in the set of identifiers, and the second set of data comprises at least a part of one or more subpackets of the subset of subpackets; identifying one or more data channels to be cancelled from the plurality of overlapping data channels, wherein the one or more data channels are identified based at least partly on the one or more identifiers; receiving the plurality of overlapping data channels, wherein the plurality of overlapping data channels overlap in time and frequency; and cancelling the one or more data channels of the plurality of overlapping data channels based at least partly on the first set of data.

According to another aspect, there is provided a computer readable medium comprising program instructions for causing an apparatus to perform at least the following: receiving a first set of data, wherein the first set of data comprises at least one subpacket of at least one file of a set of files; receiving a set of identifiers and a mapping indicating an association of the set of identifiers to a subset of subpackets of the set of files; receiving an indication for determining one or more identifiers associated with a second set of data to be transmitted over a plurality of overlapping data channels, wherein the one or more identifiers are comprised in the set of identifiers, and the second set of data comprises at least a part of one or more subpackets of the subset of subpackets; identifying one or more data channels to be cancelled from the plurality of overlapping data channels, wherein the one or more data channels are identified based at least partly on the one or more identifiers; receiving the plurality of overlapping data channels, wherein the plurality of overlapping data channels overlap in time and frequency; and cancelling the one or more data channels of the plurality of overlapping data channels based at least partly on the first set of data.

According to another aspect, there is provided a non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least the following: receiving a first set of data, wherein the first set of data comprises at least one subpacket of at least one file of a set of files; receiving a set of identifiers and a mapping indicating an association of the set of identifiers to a subset of subpackets of the set of files; receiving an indication for determining one or more identifiers associated with a second set of data to be transmitted over a plurality of overlapping data channels, wherein the one or more identifiers are comprised in the set of identifiers, and the second set of data comprises at least a part of one or more subpackets of the subset of subpackets; identifying one or more data channels to be cancelled from the plurality of overlapping data channels, wherein the one or more data channels are identified based at least partly on the one or more identifiers; receiving the plurality of overlapping data channels, wherein the plurality of overlapping data channels overlap in time and frequency; and cancelling the one or more data channels of the plurality of overlapping data channels based at least partly on the first set of data.

According to another aspect, there is provided an apparatus comprising at least one processor, and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to: transmit, to one or more user devices, a first set of data comprising at least one subpacket of at least one file of a set of files; transmit, to the one or more user devices, a set of identifiers and a mapping indicating an association of the set of identifiers to a subset of subpackets of the set of files; transmit, to the one or more user devices, an indication for determining one or more identifiers associated with a second set of data to be transmitted over a plurality of overlapping data channels, wherein the one or more identifiers are comprised in the set of identifiers, and the second set of data comprises at least a part of one or more subpackets of the subset of subpackets; and transmit, to the one or more user devices, the plurality of overlapping data channels, wherein the plurality of overlapping data channels overlap in time and frequency.

According to another aspect, there is provided an apparatus comprising means for: transmitting, to one or more user devices, a first set of data comprising at least one subpacket of at least one file of a set of files; transmitting, to the one or more user devices, a set of identifiers and a mapping indicating an association of the set of identifiers to a subset of subpackets of the set of files; transmitting, to the one or more user devices, an indication for determining one or more identifiers associated with a second set of data to be transmitted over a plurality of overlapping data channels, wherein the one or more identifiers are comprised in the set of identifiers, and the second set of data comprises at least a part of one or more subpackets of the subset of subpackets; and transmitting, to the one or more user devices, the plurality of overlapping data channels, wherein the plurality of overlapping data channels overlap in time and frequency.

According to another aspect, there is provided a method comprising: transmitting, to one or more user devices, a first set of data comprising at least one subpacket of at least one file of a set of files; transmitting, to the one or more user devices, a set of identifiers and a mapping indicating an association of the set of identifiers to a subset of subpackets of the set of files; transmitting, to the one or more user devices, an indication for determining one or more identifiers associated with a second set of data to be transmitted over a plurality of overlapping data channels, wherein the one or more identifiers are comprised in the set of identifiers, and the second set of data comprises at least a part of one or more subpackets of the subset of subpackets; and transmitting, to the one or more user devices, the plurality of overlapping data channels, wherein the plurality of overlapping data channels overlap in time and frequency.

According to another aspect, there is provided a computer program comprising instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: transmitting, to one or more user devices, a first set of data comprising at least one subpacket of at least one file of a set of files; transmitting, to the one or more user devices, a set of identifiers and a mapping indicating an association of the set of identifiers to a subset of subpackets of the set of files; transmitting, to the one or more user devices, an indication for determining one or more identifiers associated with a second set of data to be transmitted over a plurality of overlapping data channels, wherein the one or more identifiers are comprised in the set of identifiers, and the second set of data comprises at least a part of one or more subpackets of the subset of subpackets; and transmitting, to the one or more user devices, the plurality of overlapping data channels, wherein the plurality of overlapping data channels overlap in time and frequency.

According to another aspect, there is provided a computer program comprising instructions for causing an apparatus to perform at least the following: According to another aspect, there is provided a computer program comprising instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: transmitting, to one or more user devices, a first set of data comprising at least one subpacket of at least one file of a set of files; transmitting, to the one or more user devices, a set of identifiers and a mapping indicating an association of the set of identifiers to a subset of subpackets of the set of files; transmitting, to the one or more user devices, an indication for determining one or more identifiers associated with a second set of data to be transmitted over a plurality of overlapping data channels, wherein the one or more identifiers are comprised in the set of identifiers, and the second set of data comprises at least a part of one or more subpackets of the subset of subpackets; and transmitting, to the one or more user devices, the plurality of overlapping data channels, wherein the plurality of overlapping data channels overlap in time and frequency.

According to another aspect, there is provided a computer readable medium comprising program instructions for causing an apparatus to perform at least the following: transmitting, to one or more user devices, a first set of data comprising at least one subpacket of at least one file of a set of files; transmitting, to the one or more user devices, a set of identifiers and a mapping indicating an association of the set of identifiers to a subset of subpackets of the set of files; transmitting, to the one or more user devices, an indication for determining one or more identifiers associated with a second set of data to be transmitted over a plurality of overlapping data channels, wherein the one or more identifiers are comprised in the set of identifiers, and the second set of data comprises at least a part of one or more subpackets of the subset of subpackets; and transmitting, to the one or more user devices, the plurality of overlapping data channels, wherein the plurality of overlapping data channels overlap in time and frequency.

According to another aspect, there is provided a non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least the following: transmitting, to one or more user devices, a first set of data comprising at least one subpacket of at least one file of a set of files; transmitting, to the one or more user devices, a set of identifiers and a mapping indicating an association of the set of identifiers to a subset of subpackets of the set of files; transmitting, to the one or more user devices, an indication for determining one or more identifiers associated with a second set of data to be transmitted over a plurality of overlapping data channels, wherein the one or more identifiers are comprised in the set of identifiers, and the second set of data comprises at least a part of one or more subpackets of the subset of subpackets; and transmitting, to the one or more user devices, the plurality of overlapping data channels, wherein the plurality of overlapping data channels overlap in time and frequency.

LIST OF DRAWINGS

In the following, various example embodiments will be described in greater detail with reference to the accompanying drawings, in which

FIG. 1 illustrates an example embodiment of a cellular communication network;

FIG. 2 illustrates two examples for coded caching operation;

FIG. 3 illustrates a schematic representation for two different coded caching approaches;

FIG. 4 illustrates an example of data identification signalling;

FIGS. 5A and 5B illustrate examples of transmission parameter signalling;

FIG. 6 illustrates a signalling diagram according to an example embodiment;

FIG. 7 illustrates an example of data identification signalling;

FIG. 8 illustrates an example of transport blocks;

FIG. 9 illustrates a flow chart according to an example embodiment;

FIG. 10 illustrates a flow chart according to an example embodiment;

FIG. 11 illustrates an example embodiment of an apparatus; and

FIG. 12 illustrates an example embodiment of an apparatus.

DETAILED DESCRIPTION

The following embodiments are exemplifying. Although the specification may refer to “an”, “one”, or “some” embodiments] in several locations of the text, this does not necessarily mean that each reference is made to the same embodiments], or that a particular feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments.

In the following, different example embodiments will be described using, as an example of an access architecture to which the example embodiments may be applied, a radio access architecture based on longterm evolution advanced (LTE Advanced, LTE-A], new radio (NR, 5G], beyond 5G, or sixth generation [6G] without restricting the example embodiments to such an architecture, however. It is obvious for a person skilled in the art that the example 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 may be the universal mobile telecommunications system (UMTS) radio access network (UTRAN or E-UTRAN), long term evolution (LTE, substantially the same as E-UTRA), wireless local area network (WLAN or Wi-Fi), 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 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 may also comprise other functions and structures than those shown in FIG. 1.

The example 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 radio cell with an access node 104, such as an evolved Node B (abbreviated as eNB or eNodeB) or a next generation Node B (abbreviated as gNB or gNodeB), providing the radio cell. The physical link from a user device to an access node may be called uplink or reverse link, and the physical link from the access node to the user device may be called downlink or forward link. A user device may also communicate directly with another user device via sidelink communication. It should be appreciated that access nodes or their functionalities may be implemented by using any node, host, server or access point etc. entity suitable for such a usage.

A communication system may comprise more than one access node, in which case the access nodes 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 access node may be a computing device configured to control the radio resources of communication system it is coupled to. The access node may also be referred to as a base station, a base transceiver station (BTS), an access point or any other type of interfacing device including a relay station capable of operating in a wireless environment. The access node may include or be coupled to transceivers. From the transceivers of the access node, a connection may be 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 access node may further be connected to a core network 110 (CN or next generation core NGC). Depending on the system, the counterpart on the CN side may be a serving gateway (S-GW, routing and forwarding user data packets), packet data network gateway (P-GW) for providing connectivity of user devices to external packet data networks, user plane function (UPF), mobility management entity (MME), access and mobility management function (AMF), or location management function (LMF), etc.

The user device illustrates one type of an apparatus to which resources on the air interface may be 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 may be a layer 3 relay (self-backhauling relay) towards the access node. The self-backhauling relay node may also be called an integrated access and backhaul (LAB) node. The 1AB node may comprise two logical parts: a mobile termination (MT) part, which takes care of the backhaul link(s) (i.e., link(s) between 1AB node and a donor node, also known as a parent node) and a distributed unit (DU) part, which takes care of the access link(s), i.e., child link(s) between the 1AB node and user device(s), and/or between the 1AB node and other 1AB nodes (multi-hop scenario).

Another example of such a relay node may be a layer 1 relay called a repeater. The repeater may amplify a signal received from an access node and forward it to a user device, and/or amplify a signal received from the user device and forward it to the access node.

The user device may also be called a subscriber unit, mobile station, remote terminal, access terminal, user terminal, terminal device, or user equipment (UE) just to mention but a few names or apparatuses. The user device may refer 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 may be 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 maybe provided with the ability to transfer data over a network without requiring human-to-human or human-to-computer interaction. The user device may also utilize cloud. In some applications, a user device may comprise a small portable or wearable device with radio parts (such as a watch, earphones or eyeglasses) and the computation may be carried out in the cloud. The user device (or in some example embodiments a layer 3 relay node) may be configured to perform one or more of user equipment functionalities. The user device may also comprise, or be comprised in, a robot or a vehicle such as a train or a car.

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 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 may have 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 (M1M0) 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 may 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 may have multiple radio interfaces, namely below 6GHz, 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 may be provided by the LTE, and 5G radio interface access may come from small cells by aggregation to the LTE. In other words, 5G may support both inter-RAT operability (such as LTE-5G) and inter-Rl operability (inter-radio interface operability, such as below 6GHz - cmWave - mmWave). One of the concepts considered to be used in 5G networks may be 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 may be fully distributed in the radio and fully centralized in the core network. The low latency applications and services in 5G may need to bring the content close to the radio which leads to local break out and multiaccess edge computing (MEC). 5G may enable analytics and knowledge generation to occur at the source of the data. This approach may need leveraging resources that may not be continuously connected to a network such as laptops, smartphones, tablets and sensors. MEC may provide a distributed computing environment for application and service hosting. It may also have the ability to store and process content in close proximity to cellular subscribers for faster response time. Edge computing may cover 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 may also be 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 (NFV) 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 (RRH) or a radio unit (RU), or an access node comprising radio parts. It may also be possible that node operations are distributed among a plurality of servers, nodes or hosts. Carrying out the RAN real-time functions at the RAN side (in a distributed unit, DU 104) and non-real time functions in a centralized manner (in a central unit, CU 108) may be enabled for example by application of cloudRAN architecture.

It should also be understood that the distribution of labour between core network operations and access node operations may differ from that of the LTE or even be non-existent. Some other technology advancements that may be used include big data and all-lP, which may change the way networks are being constructed and managed. 5G (or new radio, NR) networks maybe designed to support multiple hierarchies, where MEC servers may be placed between the core and the access node. It should be appreciated that MEC may be applied in 4G networks as well.

5G may also utilize non-terrestrial communication, for example satellite communication, to enhance or complement the coverage of 5G service, for example by providing backhauling. Possible use cases may be 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). At least one satellite 106 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.

6G networks are expected to adopt flexible decentralized and/or distributed computing systems and architecture and ubiquitous computing, with local spectrum licensing, spectrum sharing, infrastructure sharing, and intelligent automated management underpinned by mobile edge computing, artificial intelligence, short-packet communication and blockchain technologies. Key features of 6G may include intelligent connected management and control functions, programmability, integrated sensing and communication, reduction of energy footprint, trustworthy infrastructure, scalability and affordability. In addition to these, 6G is also targeting new use cases covering the integration of localization and sensing capabilities into system definition to unifying user experience across physical and digital worlds.

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 access nodes, the user device may have an access to a plurality of radio cells and the system may also comprise other apparatuses, such as physical layer relay nodes or other network elements, etc. At least one of the access nodes may be a Home eNodeB or a Home gNodeB.

Furthermore, the access node may also be split into: a radio unit (RU) comprising a radio transceiver (TRX), i.e., a transmitter (Tx) and a receiver (Rx); one or more distributed units (DUs) that may be used for the so-called Layer 1 (LI) processing and real-time Layer 2 (L2) processing; and a central unit (CU) (also known as a centralized unit) that may be used for non-real-time L2 and Layer 3 (L3) processing. The CU may be connected to the one or more DUs for example by using an Fl interface. Such a split may enable the centralization of CUs relative to the cell sites and DUs, whereas DUs may be more distributed and may even remain at cell sites. The CU and DU together may also be referred to as baseband or a baseband unit (BBU). The CU and DU may also be comprised in a radio access point (RAP).

The CU may be defined as a logical node hosting higher layer protocols, such as radio resource control (RRC), service data adaptation protocol (SDAP) and/or packet data convergence protocol (PDCP), of the access node. The DU may be defined as a logical node hosting radio link control (RLC), medium access control (MAC) and/or physical (PHY) layers of the access node. The operation of the DU may be at least partly controlled by the CU. The CU may comprise a control plane (CU-CP), which may be defined as a logical node hosting the RRC and the control plane part of the PDCP protocol of the CU for the access node. The CU may further comprise a user plane (CU-UP), which may be defined as a logical node hosting the user plane part of the PDCP protocol and the SDAP protocol of the CU for the access node.

Cloud computing platforms may also be used to run the CU and/or DU. The CU may run in a cloud computing platform, which may be referred to as a virtualized CU (vCU). In addition to the vCU, there may also be a virtualized DU (vDU) running in a cloud computing platform. Furthermore, there may also be a combination, where the DU may use so-called bare metal solutions, for example application-specific integrated circuit (ASIC) or customer-specific standard product (CSSP) system-on-a-chip (SoC) solutions. It should also be understood that the distribution of labour between the above-mentioned access node units, or different core network operations and access node operations, may differ. 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 may be large cells having a diameter of up to tens of kilometers, or smaller cells such as micro-, femto- or picocells. The access node(s) 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 radio cells. In multilayer networks, one access node may provide one kind of a radio cell or radio cells, and thus a plurality of access nodes may be 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” access nodes may be introduced. A network which may be able to use “plug-and-play” access nodes, may include, in addition to Home eNodeBs or Home gNodeBs, a Home Node B gateway, or HNB-GW (not shown in FIG. 1). An HNB-GW, which may be installed within an operator’s network, may aggregate traffic from a large number of Home eNodeBs or Home gNodeBs back to a core network.

Coded caching may be used as a tool to increase the achievable data rate of communication links, for example for multi-media traffic, with the help of the available storage memory in network devices. Coded caching may enable the data storage space of network devices to be used as a new communication resource. The performance gain from coded caching, also known as the coded caching gain, may scale with the total cache memory size in all of the network devices. Moreover, the coded caching gain can also be combined with the spatial multiplexing gain of multi-antenna communications at both the transmitter and receiver sides. The key to achieving this combined gain may be in multicast-beamforming created codewords (or other combinations of data) to different groups of UEs, such that for every codeword, a given receiver in the target group can remove part of the interference using its cache contents.

For further clarification of coded caching principles, in FIG. 2, two examples for coded caching operation in single and multi-antenna setups are illustrated. In FIG. 2, block 210 illustrates the single-antenna setup, and block 220 illustrates the multi-antenna setup.

In the single-antenna setup 210, it may be assumed that two equal-sized files, denoted as A and B, exist in the set of data files (called “library”), and a given UE 211, 212 has enough memory size to cache one of the files. During a so-called placement phase, which may occur for example under favorable radio channel conditions, in the vicinity of a high-throughput access node (“data shower”) or at the time of a low network load, a given file may be split into two equal-sized smaller subpackets. For example, file A may be split into two smaller subpackets denoted as A₁, A₂, and file B may be split into two smaller subpackets denoted as B₂. Then, A₁ B₁ maybe stored in the cache memory of the first UE 211, and A₂, B₂ may be stored in the cache memory of the second UE 212. In a subsequent delivery phase, if, for example, the first UE 211 requests file A, and the second UE 212 requests file B, the server 213 may multicast to both UEs 211,

212, where denotes a bit-wise exclusive or (XOR) operation. After this transmission, the first UE 211 may remove the unwanted term from the received demodulated XOR signal using its cache content B₁ and extract which enables it to

reconstruct file A as it has A₁ already cached in its memory. Similarly, the second UE 212 may remove A₂ from the received signal using its cache contents and extract B₁. Irrespective of which files are requested, the size of the transmitted codeword is half of the file size. In comparison, without coded caching, whole files may be stored by the UEs, and the average transmit size may be twice as large. In other words, for this network situation, coded caching may enable an improvement by a factor of two in the total perceived data rate of the shared communication link.

The multi-antenna setup 220 comprises three UEs 221, 222, 223, wherein a given UE has a cache size sufficient for storing one file. Herein a given UE may request content from a library of three files A, B, and C from a server 224 equipped with two transmit antennas. In this case, the server 224 may combine the spatial multiplexing and coded caching gains to serve all the three UEs with a single transmission. This may be done by selecting all subsets of two UEs out of three, creating a codeword for a given subset similar to the single-antenna case, and using beamformers to suppress the extra interference that cannot be removed with the cache contents. For example, if the first UE 221 requests file A, the second UE 222 requests file B, the third UE 223 requests file C, and the cache contents are as shown in block 220, the server may transmit:

where v_k is the beamforming vector used to suppress data at UE k. Then, for example, at the first UE, the term

may be suppressed by the beamforming vector v₁ (assuming zero forcing, ZF, beamformer under ideal assumptions), and the interference terms inside and may be removed by cache contents. As the first UE

has A₁ already cached in its memory, it can then decode the requested file A. Similarly, the second UE can decode file B, and the third UE can decode file C with no interference. Note that ZF beamforming is assumed here for simplicity. Thus, performance gains may be achieved at low or medium signal-to-noise ratio (SNR) levels by using optimized minimum mean square error (MMSE) type multicast beamformers.

Coded caching may provide improvements on perceived data rate and on efficient use of communication link resources. Excess or idle communication link resources may be used possibly at high efficiency during the placement phase to alleviate or reduce the need for communication link resources after the network device requests for data and, possibly, to avoid or mitigate temporal shortage of communication link resources. Hence, coded caching allows for more efficient use of resources. At the network device, the requested data is perceived to be delivered in a shorter time at improved data rate. In general, in a case of single spatial stream in downlink (DL) and network situation of K UEs, wherein a given UE has a cache size sufficient to store M files and requesting from a library of N files, coded caching may improve the achievable performance up to a factor of t = KM /N, where t is the coded caching gain. For the same network situation, if the server has a spatial multiplexing gain of L, the achievable data rate may be improved up to a factor of t + L. Finally, if a given receiver also has a spatial multiplexing gain of G and L ≥ G, the data rate improvement factor may be up to Gt + L.

However, there may be limitations to the scenarios where coded caching can provide benefits. Coded caching techniques may be well-suited to application scenarios where some nearby UEs, e.g., UEs that are served by the same cell, the same sector of a cell, or by the same transmit/receive point of a cell, request data from a well-defined library (i.e., the number of files that may be requested by UEs is limited and known). It should be mentioned that the limited library size in coded caching does not mean that different UEs should request the same data (i.e., a multicast scenario). In other words, the UEs may request data from the same set of data files, but at a given time, the UEs may request different files (i.e., the same file cannot be multi-casted to all UEs). In fact, coded caching gains are achievable even if every UE is requesting a different file. File fragments from the library can be cached at the UEs beforehand. Content placement in cache memories may occur, for example, when the network traffic is low or when UEs are close to a high-throughput access node (data shower) and high throughput can be used during the placement of content in cache memories.

For further clarification, in the following, two example use cases for extended reality (XR) are described, where coded caching techniques may help to improve the data rate and/or Quality of Experience (QoE) of a given UE.

The first example use case is a wireless XR gaming application, where some users with high-end mounted eyewears (acting as UEs) request data from the server at periodic time intervals. The requested data may be used for recreating appropriate viewpoints for the users following their locations (and head orientations) at the request interval. It may be assumed that part of the requested data (e.g., the data needed to render the background scenery or virtual infrastructure of every user's field of view) is static during the time and can be cached beforehand. In such an XR application scenario, the simultaneous delivery of the high-data-rate and low-latency streams requested by all users may create traffic demand that even the most sophisticated networks have difficulties to handle. However, coded caching techniques may help to address such issues by offloading a significant part of the communication to the UE storage memories available throughout the network.

For example, assume 20 users engaged in an XR application that runs in a 20x20 meters environment. The application environment may be split into 1600 square tiles of 50x50 centimeters, and a separate file with a size of 100 MB may be needed to recreate the high-quality three-dimensional (3D) omnidirectional scenery view of the user in a given tile. The area may be served by a two-antenna transmitter, and a given UE may have a cache memory with a size of 16 GB. In such a scenario, coded caching techniques may enable serving up to four users interference-free during a given transmission overlapping in time-frequency, which may be a two-fold increase compared with the number possible when relying exclusively on beamforming techniques.

The second example use case is a wireless XR museum application, where a group of users entering a museum wear XR headsets (acting as UEs) and move together throughout the museum area. The area may consist of different rooms, where in a given room, a different part of the history may be presented. As the users enter a room, they may be engaged in a virtual reality video representing events in the respective historical era. The users can move in the room, and their scenery may change based on their location at any given moment.

For example, assume a group of ten users, and the room has a dimension of 5x5 meters. Moreover, the room area may be split into 100 square tiles of 50x50 centimeters, and a separate file of size 100 MB may be needed to recreate the high-quality 3D omnidirectional scenery view of the user in a given tile. The area may be served by a two-antenna transmitter, and a given UE may have a cache memory with a size of 4 GB. In this case, coded caching techniques may enable serving up to six users during a given transmission, which may be a three-fold increase compared to the case of relying exclusively on spatial multiplexing gain.

However, coded caching may also involve some challenges. For one, as can also be seen from the examples of FIG. 2, coded caching techniques may require splitting files into smaller parts, called subpackets. The required number of these subpackets, known as subpacketization, may grow exponentially with the number of users.

Second, some coded caching techniques may require prior knowledge of the user count to specify which data should be cached at a given UE. Such a dependency may make these coded caching techniques unsuitable for dynamic networks, where users can freely move and join or leave the network or relevant application at any moment. Although a class of schemes, known as decentralized coded caching, may be used to combat this issue, they may not provide much of a gain unless the user count is very large.

A third challenge is that achieving the combined coded caching and spatial multiplexing gains may require somewhat more complex beamformer designs suited for multi-group multicast transmissions.

Finally, the fourth challenge, known as the near-far problem, is rooted in the underlying multicast nature of coded caching schemes that causes the data rate of a given transmission to be limited by the achievable data rate at the UE with the worst radio channel conditions. This may cause issues when the UEs experience vastly different radio channel qualities (e.g., due to different fading conditions), as the data rate (and hence, the quality of experience) at UEs with good radio channel quality would be deteriorated, if served using cache-aided multicast delivery.

For the above reasons, current coded caching schemes may be more suited to small, static networks, and hence the specific requirements for cellular deployment should be carefully considered. In other words, there may be a need to develop coded caching schemes that are more suitable for cellular deployments, while providing gains similar to the ones described in the above examples.

Signal-level coded caching is a class of coded caching schemes with a different cache-aided interference cancellation approach. Signal-level coded caching may address the challenges mentioned above. For example, signal-level coded caching may have a minimal subpacketization requirement, enable simpler beamformer designs, provide flexibility for dynamic network conditions, and pave the way for addressing the near-far issue by supporting different streams with specific data rates. A difference of the signal-level coded caching schemes compared to the other coded caching schemes is that the cache-aided interference cancellation is made before the decoding happens at the receiver (i.e., in the signal domain). This contrasts with the other approaches, where the cache contents are used in the finite field after decoding. Due to this property, the term “signal-level” is used herein to describe this class of coded caching schemes, whereas the term “bit-level” may be used herein to describe the other schemes.

FIG. 3 illustrates a schematic representation of these two approaches for the multi-antenna example network illustrated in block 220 of FIG. 2. In FIG. 3, block 310 illustrates bit-level coded caching, and block 320 illustrates signal-level coded caching.

FIG. 3 shows the codeword generated for a first UE and a second UE as well as the decoding process at the first UE, assuming these two UEs request files A and B, respectively. As can be seen, in the bit-level approach 310, the two terms A₂ and B₁ are first encoded using a XOR operation in the finite-field, and then, after channel encoding (not shown in FIG. 3), a single beamformer v₃ is used to suppress the interference at a third UE. Then, at the receiver of the first UE, the received signal is first decoded and then the cached term B₁ is used to recover the requested term A₁.

However, in the signal-level approach 320, two zero-forcing beamformers

and are used first, and then the resulting terms are added in the signal domain. Now, for decoding A₂, the first UE has to first remove the interference caused by B₁ in the signal domain, before decoding the received signal. As can be seen, the signal-level approach involves a different receiver structure with interference cancellation capability, where the cache contents are used in the signal domain for interference cancellation.

The signal-level coded caching schemes may require the receivers to be aware of various physical layer parameters regarding the transmitted message. For example, the receivers should know which interference terms are intended to be removed with cache contents at a given UE, as well as how to regenerate these interference terms. Informing such a large number of parameters to the receivers may require additional signalling at the physical layer. This additional signalling should incur a low overhead, which may be difficult for coded caching schemes, as they may require consecutive transmissions of many messages, wherein a given message may be intended for a different subset of UEs and involve a large number of transmission parameters. Moreover, the signalling mechanism should be flexible enough to support upcoming use cases and variations.

More specifically, data delivery with coded caching may be done through a number of transmissions, where a given transmission time interval (TT1) comprises multiple overlapping transmissions (in time-frequency resources) targeted to a specific subset of UEs. Hence, transmission time intervals comprise several combinations of data (i.e., subpackets from different files that are transmitted concurrently, which may be referred to as “data combination”). To receive the data, a given receiver may need to know the transmission parameters, such as resource allocation, modulation and coding scheme (MCS), demodulation reference signal (DMRS) configuration, hybrid automatic repeat request (HARQ) process ID, etc., for the data intended to it. Furthermore, the receiver may also need to know transmission parameters and data identifications for at least some of the concurrent transmissions targeted to other UEs. However, with straightforward signalling, this may result in too large physical layer downlink control information. Some example embodiments may address this issue.

In the above, transmission may refer to a single transmission of a HARQ process, such as a single physical downlink shared channel (PDSCH). The transmission time interval may refer to time-domain resources, such as a number of orthogonal frequency-division multiplexing (OFDM) symbols used for a transmission.

Some example embodiments are described below using principles and terminology of 5G technology without limiting the example embodiments to 5G communication systems, however.

Some example embodiments may provide a signalling mechanism for coded caching that allows the access node (e.g., gNB) to indicate the required information to the UE(s). The control signalling for a TT1 may be split into two phases: semi-static signalling, which may be valid for multiple consecutive TTls, and dynamic signalling, which may be relevant for one corresponding TT1. The semi-static signalling may compress the indication or identification of all data contained in the data combination transmitted over multiple downlink data channels in a TT1.

The signalling mechanism provided by some example embodiments may reduce signalling overhead, as well as provide flexibility for future developments. The signalling may occur on the physical layer, thus enabling the usage of the signal-level coded caching scheme. Some example embodiments may improve achievable data rates for example for interactive multi-media traffic in 5G or 6G. However, it should be noted that some example embodiments are not limited to 5G and 6G.

In the following, the control signalling is described in two parts: data identification signalling and transmission parameter signalling. In the data identification signalling (illustrated in FIG. 4), the access node may indicate all the subpackets sent within multiple TTIs. It may also be possible that, within a transmission, just a sub-block or fragment of the subpacket is transmitted (e.g., when the length of the subpacket is large). As mentioned above, the data identification signalling may comprise two phases: semi-static signalling and dynamic signalling. In the semi-static signalling phase, the access node first maps a given subpacket in a set of subpackets to a temporary short identifier (i.e., the set of subpackets is to be transmitted over the following set of TTIs). The set of subpackets comprises a subset of subpackets for the set of files (i.e., the temporary short identifiers cover just a part of the library). Then, the access node may use the temporary short identifiers in the dynamic signalling phase, which provides the actual scheduling for data block transmissions. In the following, two alternative approaches are described, wherein both approaches comprise separate semistatic and dynamic signalling phases.

In the first alternative for the data identification signalling (called “alternative A” herein), the access node allows more flexibility (compared to the second alternative) in selecting which data combination is sent within a given TTI. In the semi-static signalling phase of alternative A, the access node informs temporary short identifiers and their equivalent content association (e.g., file identifier, subpacket identifier) to all the users participating in the coded caching delivery.

In the dynamic signalling phase of alternative A, before a given transmission, the access node informs target UEs of the list of temporary short identifiers of the data sent within that transmission.

The second alternative for the data identification signalling (called “alternative B” herein) may incur less signalling overhead, but it may be more rigid with selecting the data combinations sent with a given transmission. The difference with alternative A is that a data combination subpacket index is associated to a specific subset of file identifiers and subpacket identifiers. For example, the file identifiers and subpacket identifiers may be sorted in a data structure such as a table, where a given row in the table indicates a specific subset of file identifiers and subpacket identifiers that will be sent within a single transmission time interval. In the context of alternative B, the term “data combination subpacket index” is used to refer to a specific row index in the table. The table may be sorted following a specific underlying coded caching scheme. However, it should be noted that this is just one option for the structure of the table, and different structures may also be used. In the semi-static signalling phase of alternative B, the access node informs the data combination subpacket indexes and their equivalent content association (e.g., file identifier, subpacket identifier) to all UEs participating in the coded caching delivery.

In the dynamic signalling phase of alternative B, before a given transmission, the access node informs target UEs of the data combination subpacket index for the data sent within that specific transmission.

Alternatively, the data combination subpacket index may not be included in the dynamic signalling. Instead, in this case, UEs just move to the next row on the semi- statically indicated sorted table whenever new data is indicated in the dynamic signalling.

FIG. 4 illustrates an example of the data identification signalling for the alternatives A and B described above. In FIG. 4, a given block 401, 402 represents a single semi-static signalling window. A given rectangle 403 in the blocks 401, 402 represents a subpacket. In this example, data is delivered to three UEs, and a given row in the blocks 401, 402 represents subpackets transmitted to one UE. The subpackets 403 within the blocks 401, 402 are the subset of subpackets that can be indicated with temporary short identifiers provided with semi-static signalling. The dynamic signalling may be provided for example through physical downlink control channel (PDCCH).

In alternative A, dynamic control signalling, for example downlink control information (DCI) 410, 411, 412, may indicate any combination of subpackets within the semi-static subset, as shown with the arrows.

In alternative B, data combinations are defined in the semi-static signalling, and a data combination subpacket index in the DCI 420, 421, 422 indicates a data combination 423, 424, 425.

The transmission parameter signalling (part of the dynamic control signalling) indicates parameters for multiple overlapping physical DL data channels (e.g., PDSCHs in case of 5G) used for coded caching. The signalling may be used by the UE(s) to cancel or suppress the interference caused by other overlapping physical DL data channels and to perform the detection of the requested data. The transmission parameter signalling can be done with two alternatives, based on unicast or multicast nature of the control signalling, as illustrated in FIGS. 5A and 5B.

FIG. 5A illustrates an example of the transmission parameter signalling according to the first alternative (called “alternative I” herein). In this alternative, the access node 511 provides the DL control signalling separately per UE 512, 513, 514.

The DL control signalling of alternative I may comprise, for example, the time and frequency domain resource allocations and other parameters (e.g., HARQ feedback timing) that are common for all overlapping physical DL data channels. As these parameters are common for the UEs 512, 513, 514, a given UE may use these parameters for detecting the DL data channel intended for that specific UE. The UE may also use some of these parameters, for example the time and frequency resource allocations, in interference cancellation.

The DL control signalling of alternative 1 may further comprise a set of transmission parameters for the UE’s own requested data (e.g., DMRS index, MCS index, and a data/transport block index), unless semi-statically configured. A given UE may use the set of transmission parameters for detecting the DL data channel intended for that specific UE.

The DL control signalling of alternative 1 may further comprise a set of transmission parameters for co-scheduled UEs, used for interference cancellation. Note that part of the interference may be suppressed spatially (e.g., with beamforming), and the other part may be removed with the help of cache contents.

For the spatially suppressed interference, the transmission parameters may comprise, for example, DMRS indexes, which allow a given UE to estimate the combined impact of channel and beamforming (if any) for one or more interfering DL data channels (of one or more co-scheduled UEs) and perform spatial interference suppression at the receiver (if necessary).

For the cache-aided interference cancellation, the transmission parameters may comprise the set of temporary short identifiers (if alternative A is used for data identification signalling) or the data combination sub-packet index (if alternative B is used for data identification signalling). The transmission parameters may further comprise the transport block index, when a fraction of a subpacket is transmitted per TT1. The transmission parameters may also comprise other parameters required for regenerating the interfering signal(s), for example DMRS indexes (to estimate the combined impact of channel and beamforming) and MCS indexes. It should also be noted that some of these transmission parameters (e.g., MCS) may be semi-statically set during the semi-static phase of the data identification signalling.

FIG. 5B illustrates an example of the transmission parameter signalling according to the second alternative (called “alternative 11” herein). In this alternative, the access node 521 provides the DL control signalling as common for all UEs 522, 523, 524 participating in the coded caching data delivery. This DL control signalling may be provided for example with group-casting of PDCCH.

The DL control signalling of alternative 11 may comprise, for example, the time and frequency domain resource allocations and other parameters (e.g., HARQ feedback timing) that are common for all overlapping physical DL data channels.

The DL control signalling of alternative 11 may further comprise a set of transmission parameters for all overlapping physical DL data channels, including, for example, DMRS index, MCS, HARQ process ID, and power control command. These parameters are specific for a given DL data channel. A given UE may use these parameters to detect the DL data channel intended for the UE, and to regenerate and cancel interference from DL data channels for which the UE has data available on the cache. For example, for a given overlapping DL data channel, the UE may use the DMRS index to estimate the channel, and the channel estimate may be used in: a) detection of the DL data channel intended to the UE, b) in regenerating DL data channel interference for which the UE has data in cache memory and subtracting the regenerated DL data channel interference from the received signal, and/or c) in spatial interference suppression for other co-scheduled UEs.

The DL control signalling of alternative 11 may further comprise the set of temporary short identifiers (if alternative A is used for data identification signalling) or the data combination subpacket index (if alternative B is used for data identification signalling), as well as the transport block index.

The transmission parameters and the dynamic signalling phase of the data identification signalling may be transmitted on a single DC1. It should be noted that some of the transmission parameters (e.g., MCS) may be semi-statically set during the semistatic phase of the data identification signalling.

A given UE may determine the physical DL data channel that it regenerates for cache-aided interference cancellation based on the temporary short identifier or subpacket index associated with the transmission parameter sets, as well as based on data stored in its memory. Herein the memory may refer to a mass storage (e.g., solid-state drive) available on the UE, on which data may be stored during the placement phase of coded caching operation.

Further, a given UE may determine the physical DL data channel that it will receive based on the temporary short identifier or sub-packet index associated with the transmission parameter sets, as well as based on its higher layer data request.

Signal-level interference cancellation may be beneficial in practical implementation of coded caching schemes. For example, it may allow smaller subpacketization, simpler optimized beamformer design, and applicability to dynamic networks, where the UEs can join and leave the network freely. However, it may also necessitate a receiver structure that is aware of the interference terms that should be removed with the cache contents in the physical layer. As a result, control signalling may be needed to provide the receiver with the required information.

An example on coded caching is provided in the following. This example relates to the transmission and decoding process for a small network of four singleantenna UEs requesting files from a two-antenna transmitter. The library consists of four files and a given UE has a cache memory large enough to store one file.

Hence, three UEs can be served with a single transmission, i.e., the total achievable degree of freedom (DoF) is three. During the placement phase, a given file may be split

into four packets and packets

may be stored in the cache memory of UE k for every

file For example, packets A₁, B₁, C₁, and D₁ may be stored in the cache memory of

a first UE.

During the delivery phase, the first UE, second UE, third UE and fourth UE may request the files A, B, C, and D, respectively. Data delivery for these four UEs can be done with 4 x 3 = 12 transmissions, wherein a given transmission delivers data to three UEs interference-free. T o build the transmission vectors, the access node may first split a given packet W_i into three equal-sized subpackets where Then, the first

transmission vector may be built for example as follows:

where v_k is the beamforming vector suppressing its associated term at UE k. It can be shown that, with the proper receiver structure, the transmission vector x(1) delivers data to the first, second, and third UEs interference-free. For example, defining h_k to be the channel vector from two transmit antennas to UE k, and z_k to be the additive white Gaussian noise (AWGN) at this UE, after the transmission of x(1), the received signal at the receiver of the first UE may be:

Now, assuming that the receiver at the first UE knows that the data terms B and are included with x(1) and their respective channel multiplier (estimated from the stream-specific downlink DMRS) are and respectively, it can reconstruct

and remove the interference term using its cache contents (as it has B₁

and in its cache), and decode A₂ interference-free. Similarly, the received signal at the receiver of the second UE may be:

However, following the beamformer vector definition, the interference term is suppressed atthe second UE. Now, assuming that the receiver atthe second UE

knows that the data term A₂ is included in x(1) and its channel multiplier is it can

reconstruct and remove the remaining interference term

to decode

interference-free.

With a similar process, the third UE can also decode C₄ (note that for this UE, both interference terms are suppressed by beamforming), and hence all the UEs in the target group may receive parts of their requested data interference-free.

After the transmission of x(1), the access node may proceed by building its following transmission vector x(2) as:

to deliver data to the first, third and fourth UEs interference-free. After the transmission of x(2), the first UE may receive:

and reconstruct and remove the interference term

using its cache contents (and the knowledge of the channel multipliers) to decode A₃ interference-free.

Similarly, the third UE may receive:

However, the interference term may be suppressed by the

beamforming vector v₃, and hence, this UE may need to reconstruct the remaining interference term to decode

interference-free. It can also be checked that the

fourth UE can decode D₄ interference-free. By following this procedure for all of the twelve transmissions, all of the UEs may receive their missing data elements and recover their requested files.

From the example above, it can be observed that the delivery phase in coded caching schemes may comprise a number of consecutive transmissions, where a given transmission targets a different subset of UEs. The exact number of transmissions and the subset of UEs targeted during a given transmission may depend on the underlying coded caching scheme. For a given UE targeted with a transmission, some interference terms may be suppressed by beamforming and the others can be removed with cache contents. The number of interference terms removed by cache contents may not be uniform for all of the UEs targeted with the transmission, and it may depend on the underlying coded Z1 caching scheme. Cache-aided interference cancellation in signal-level coded caching schemes may be done in the signal domain, and it may require the UE to know what data element is included in a given interference term (more specifically, the memory address of the data element in the interference term), as well as the channel multiplier estimation or channel estimate for a given interference term. The information needed for cache-aided interference cancellation in signal-level coded caching schemes may vary from transmission to transmission. Even within a single transmission, the target UEs may require different data.

The above observations demonstrate the need for proper signalling in the control plane for coded caching schemes to work properly. Besides every transmission, it should be declared which UEs are targeted and how exactly they should use their cache contents to remove the interference. For a given interference term at every UE in the target group, there may be a need to communicate the cache portion (e.g., the starting address in the memory and the length of the data) to be used, as well as the respective transmission parameters for interfering signal regeneration. If not handled properly, this may lead to a large signalling overhead, effectively hindering the gains of coded caching.

As an example on data identification alone, it is assumed that the set of data files (i.e., “library”) in a coded caching delivery session comprises 100 files, and a given file is split into 30 subpackets. For this example, unique identification of subpackets may require a 12-bit identification field. Also, if there are 3 parallel transmissions that a UE needs to be aware of, the DC1 should contain 3 x 12 = 36 bits for identification of the transmitted subpackets alone.

As another example, assuming that the coded caching library comprises 1600 files and a given file is split into 160 subpackets, unique identification of sub-packets may require an 18-bit identification field. Moreover, if there are 8 parallel transmissions that a UE needs to be aware of, the DC1 should contain 8 x 18 = 144 bits for subpacket identification alone. An even larger file library may be possible in real use cases, and hence, this kind of signalling may suffer from large overhead and limited scalability.

FIG. 6 illustrates a signalling diagram according to an example embodiment. Although a group of three UEs are shown as an example in FIG. 6, it should be noted that the number of UEs may also be different than three. In other words, there may be two or more UEs in the group. In addition, the signalling procedure illustrated in FIG. 6 may be extended and applied according to the actual number of UEs.

A network element of a wireless communication network transmits a configuration 601 of a coded caching session to a group of UEs. In the configuration 601, the file and subpacket identifiers for a coded caching set of files (library) are configured to a given UE. For example, the network element may comprise, or be comprised in, an access node such as a gNB.

In the data placement 602, the network element transmits at least one subpacket of at least one file of the set of files to the UEs, and the at least one subpacket is stored in the memories of the UEs. The network element may transmit different subpacket(s) per UE. The subpacket(s) stored in a given UE may also be referred to as a first set of data herein. The data placement may be performed for example in favorable radio link and/or data traffic load situations.

A given UE of the group of UEs transmits a data request 603 for requesting one or more files from the set of files. In the data requests, the different UEs may request different file(s).

A given UE of the group of UEs receives semi-static control signalling 604 from the network element for a set of consecutive PDSCHs. The semi-static control signalling comprises a set of identifiers and a mapping indicating an association of the set of identifiers to a subset of subpackets of the set of files. The semi-static control signalling may be common for the group of UEs.

Based on the semi-static control signalling, a given UE determines 605 one or more identifiers corresponding to the first set of data stored in the memory of the UE. In case of alternative B (or alternative A used together with alternative II), the one or more identifiers may also correspond to the data requested in the data request by that UE.

A given UE of the group of UEs receives dynamic control signalling 606 from the network element for a given transmission, wherein the transmission comprises a plurality of overlapping data channels, for example PDSCHs, targeted to the different UEs in the group of UEs. The dynamic control signalling comprises an indication for determining one or more identifiers associated with a second set of data to be transmitted over the plurality of overlapping data channels, wherein the one or more identifiers are comprised in the set of identifiers, and the second set of data comprises at least a part of one or more subpackets of the subset of subpackets. It should be noted that the second set of data may comprise data that is not comprised in the first set of data (i.e., data that the UE needs to decode) as well as data that is comprised in the first set of data (i.e., data that the UE cancels). The dynamic control signalling maybe common for the group of UEs.

Herein the one or more identifiers may refer to one or more temporary short identifiers or a data combination subpacket index, which are described above. For example, the indication may comprise one or more temporary short identifiers, wherein a given temporary short identifier is associated with a single subpacket of the second set of data. Alternatively, the indication may comprise a data combination subpacket index associated with a plurality of subpackets of the second set of data.

The dynamic control signalling may also comprise a set of transmission parameters as described above. For example, the dynamic control signalling may comprise a first set of parameters for the plurality of overlapping data channels, wherein the first set of parameters comprises at least time and frequency domain resource allocations common for the plurality of overlapping data channels. A given UE may use the resource allocations to determine the time and frequency domain locations for receiving the plurality of overlapping data channels.

As another example, the dynamic control signalling may comprise a second set of parameters for channel estimation of the data channel to be decoded by a given UE, wherein the second set of parameters comprise at least one of: a demodulation reference signal index associated with the data channel to be decoded, a modulation and coding scheme index associated with the data channel to be decoded, and/or a data indicator associated with the data channel to be decoded.

As another example, the dynamic control signalling may comprise a third set of parameters for cancelling one or more interfering data channels, wherein the third set of parameters comprises at least one of: a demodulation reference signal index associated with the one or more data channels to be cancelled, and/or a modulation and coding scheme index associated with the one or more data channels to be cancelled.

As another example, the dynamic control signalling may comprise a fourth set of parameters comprising at least one of: one or more demodulation reference signal indexes associated with the plurality of overlapping data channels, one or more modulation and coding scheme indexes associated with the plurality of overlapping data channels, one or more hybrid automatic repeat request identifiers associated with the plurality of overlapping data channels, and/or one or more power control commands associated with the plurality of overlapping data channels. A given UE may use these parameters for identifying the data channel intended for it and/or for cancelling one or more interfering data channels. Herein the terms “first set of parameters”, “second set of parameters”, “third set of parameters”, and “fourth set of parameters” are just used to distinguish the parameter sets.

Based on the semi-static control signalling and dynamic control signalling comprising signalling for data combinations and transmission parameters, as well as based on its data request and the data stored to the UE’s memory, a given UE of the group of UEs identifies 607, or determines, which data channel it is intended to decode from the plurality of overlapping data channels, and which of the data channels it can cancel based on the data stored in its memory. For example, the UE may identify the data channel intended for it by checking whether the dynamic signalling comprises a temporary short identifier or data combination subpacket index associated with the file identifier^] of the one or more files requested by the UE. Similarly, the UE may identify one or more data channels to be cancelled by checking whether the dynamic signalling comprises a temporary short identifier or data combination subpacket index associated with a file identifier of a file or subpacket in the first set of data stored to its memory (from the data placement).

In case of alternative 11, where the dynamic control signalling may be provided as common for the group of UEs, a given UE may also determine whether or not it is expected to decode any of the scheduled data channels.

In case of alternative A used together with alternative 1, the dynamic control signalling (e.g., DC1) may not comprise an identifier for the data channel that the UE is intended to receive. In this case, the UE may identify the parameters for the intended data channel for example based on the parameter field location in the DC1. On the other hand, the DC1 may comprise identifiers for the data channels to be cancelled.

The network element transmits the plurality of overlapping data channels 608 to the group of UEs, wherein these data channels may be targeted to different UEs in the group of UEs. In other words, a given data channel of the plurality of overlapping data channels may be targeted to a specific UE of the group of UEs. The data channels in the plurality of overlapping data channels overlap fully or at least partially in time and frequency domain.

A given UE of the group of UEs regenerates and cancels 609 one or more other interfering data channels of the plurality of overlapping data channels based at least partly on the corresponding first set of data stored on the UE. In other words, the UE regenerates the interfering data channel(s), for which it has data in its cache (from the data placement).

Herein regeneration means encoding, rate matching, modulating the interfering data to generate a replica of the transmitted signal, and then creating a convolution with the channel estimated for the interfering signal (the channel estimate incorporating the impact of any beamforming) to generate a replica of the received interfering signal.

The cancelling may mean removing or partially removing or subtracting or suppressing the other overlapping data channel(s) that the UE receives and that interfere with the detection and decoding of the data channel intended for the UE. The purpose of the cancelling is to improve the received signal quality for the intended data channel so that the UE receiver can successfully decode the intended data channel.

In response to cancelling the one or more other interfering data channels, the identified data channel is detected and decoded 610. The identified data channel comprises a part (e.g., a subpacket) of the requested file, which may be combined with other parts comprised in one or more subsequent data channels in order to obtain the full file. In the data placement, one or more subpackets of the requested file may also be stored to the memory of the UE in the first set of data, and these pre-stored subpacket(s) may then be combined to the subpackets (second set of data) provided by the data channels, in which case the pre-stored subpackets do not need to be provided separately via the data channels.

Some examples of the content of the semi-static control signalling are shown in Tables 1 and 2 below for the alternatives A and B, respectively. For the same length of temporary short identifier, alternative B may support a larger set of data combinations transmitted over overlapping PDSCHs. With alternative A, the access node may more freely combine different subpackets to be transmitted simultaneously at the time of scheduling. In the tables, ID is an abbreviation for identifier.

Table 1.

Table 2.

The semi-static control signalling maybe transmitted several times during the delivery of requested data, as the temporary short identifier may not cover all subpackets. On other hand, it does not need to be transmitted too frequently, as the size of a single subpacket may be, for example, several megabits or tens of megabits and require transmission over numerous PDSCHs.

Semi-static transmission of such mapping of long (file + subpacket) identifiers to temporary short identifiers saves the bits on the dynamic control signalling at the expense of DL data channel resources used for semi-static signalling. Such a trade-off may be sensible, as the dynamic control signalling cannot benefit from HARQ retransmissions, meaning that higher reliability and lower code rate are required for dynamic control signalling and, hence, dynamic control signalling bits are transmitted with considerably lower spectral efficiency. Furthermore, the resources for dynamic control signalling may be limited.

The semi-static phase of the data identification signalling may also provide a given UE with sufficient time to identify temporary short identifiers corresponding to the requested data, as well as time to fetch the appropriate data blocks saved in the UE memory to be available for physical layer processing. Later, when the UE receives dynamic signalling with alternative 11, it can then identify, based on the temporary short identifier or data combination sub-packet index, whether the dynamic signalling comprises the temporary short identifier or data combination subpacket index for the data that the UE has requested. In other words, the UE may determine whether it should receive any of the scheduled PDSCHs. The UE may also identify the appropriate transmission parameter set for the PDSCH it should receive, as well as the transmission parameter sets for the PDSCHs it can cancel with the cached data.

FIG. 7 illustrates an example of the signalling for alternative A of the data identification signalling. FIG. 7 shows how the semi-static signalling phase can reduce the size of data identification in the dynamic control signalling. Instead of using identifiers that can indicate any subpacket in the whole coded caching library, the semi-static signalling determines temporary short identifiers that may indicate subpackets of the files that are currently delivered, as well as subpackets that are about to be transmitted next. As the semi-static mapping of the temporary short identifiers can be updated when needed, the signalling also flexibly supports any changes on the files that are currently delivered and is fully scalable to any amount of subpacketization required by coded caching.

Referring to FIG. 7, a given file in a library 701 of files is split into multiple subpackets (three subpackets per file 702 are shown in FIG. 7, but the actual number of subpackets per file may also be higher than three). Three files 702 are requested by three UEs (one file requested per UE). The semi-static signalling provides temporary short identifiers 703 for a subset of the subpackets of the requested files. The temporary short identifiers may be updated as needed during the data delivery, although a small overlap on the temporary short identifiers may help in the update timing. Block 704 illustrates updated temporary short identifiers. A given row in the blocks 703, 704 represents the subpackets of one file requested by a UE. The data requests for different UEs may not necessarily be synchronous, as indicated by the row 705. The DCls 706 may use the temporary short identifiers in scheduling of PDSCHs. A single subpacket may require multiple PDSCHs.

Table 3 below presents an example of the contents of the dynamic control signalling for alternatives A and B together with dynamic control signalling unicasted separately per UE, and multi-casted jointly for all UEs. From Table 3, it can be noted that dynamic identification of data (file and subpacket) may require as little as 6 bits (in alternative B) compared to the 36 bits or 144 bits required with the baseline solution discussed above. Due to the potentially large size of a subpacket, it may need to be split into multiple transport blocks (TBs). Hence, the dynamic control signalling may also comprise a TB index for the current transmission. It is noted that also those UEs using the data in cache-aided interference cancellation may need to be aware of the appropriate transport block. Hence, the one-bit new data indicator used in LTE and NR may be insufficient due to risk of errors. The TB index may be common for all UEs (in case of alternative 11), or specific per UE. The latter option allows, for example, for retransmissions within coded caching schemes, but at the expense of higher control signalling overhead.

Table 3.

Some example embodiments may allow to compress dynamic control signalling overhead also for other parameters. Some parameters may be common for all overlapping PDSCHs, while some other parameters may be set semi-statically.

FIG. 8 illustrates an example of transport blocks with UE-specific MCS values. The MCS may be set separately per UE, facilitating for the UE-specific differences in radio link qualities. Correspondingly, UEs may have transport blocks of different sizes as illustrated in FIG. 8 for two UEs (user #1 and user #2) with two different MCS values. The transport block data content for a TB index may depend on the current and past MCS values of the targeted UE (during the subpacket transmission). If the MCS is set on dynamic control signalling, there is a risk that a UE will fail to decode at least one of the dynamic control signals. In this case, this UE may lose track of the transport block content for all other UEs in coded caching, without the access node knowing it. Correspondingly, any consecutive cache-aided interference cancellation may fail, as the UE is using a wrong portion of data for interference cancellation. Hence, it may be beneficial to set MCS values semi-statically, where UEs separately acknowledge the correct reception of control signalling.

FIG. 9 illustrates a flow chart according to an example embodiment of a method performed by an apparatus such as, or comprising, or comprised in, a user device. The user device may also be called a subscriber unit, mobile station, remote terminal, access terminal, user terminal, terminal device, or user equipment (UE). The user device may correspond to one of the user devices 100, 102 of FIG. 1.

Referring to FIG. 9, in block 901, a first set of data is received, wherein the first set of data comprises at least one subpacket of at least one file of a set of files.

In block 902, a set of identifiers and a mapping indicating an association of the set of identifiers to a subset of subpackets of the set of files are received.

In block 903, an indication is received for determining one or more identifiers associated with a second set of data to be transmitted over a plurality of overlapping data channels, wherein the one or more identifiers are comprised in the set of identifiers, and the second set of data comprises at least a part of one or more subpackets of the subset of subpackets.

In block 904, one or more data channels to be cancelled are identified from the plurality of overlapping data channels, wherein the one or more data channels are identified based at least partly on the one or more identifiers.

In block 905, the plurality of overlapping data channels are received, wherein the plurality of overlapping data channels overlap in time and frequency; and

In block 906, the one or more data channels of the plurality of overlapping data channels are cancelled based at least partly on the first set of data.

FIG. 10 illustrates a flow chart according to an example embodiment of a method performed by an apparatus such as, or comprising, or comprised in, a network element of a wireless communication network. The network element may correspond to the access node 104 of FIG. 1.

Referring to FIG. 10, in block 1001, a first set of data comprising at least one subpacket of at least one file of a set of files is transmitted to one or more user devices.

In block 1002, a set of identifiers and a mapping indicating an association of the set of identifiers to a subset of subpackets of the set of files are transmitted to the one or more user devices.

In block 1003, an indication is transmitted to the one or more user devices for determining one or more identifiers associated with a second set of data to be transmitted over a plurality of overlapping data channels, wherein the one or more identifiers are comprised in the set of identifiers, and the second set of data comprises at least a part of one or more subpackets of the subset of subpackets.

In block 1004, the plurality of overlapping data channels are transmitted to the one or more user devices, wherein the plurality of overlapping data channels overlap in time and frequency.

The steps and/or blocks described above by means of FIGS. 6 and 9-10 are in no absolute chronological order, and some of them may be performed simultaneously or in an order differing from the described one. Other steps and/or blocks may also be executed between them or within them, and other information may be transmitted and/or received. Some of the steps and/or blocks or a part of the steps and/or blocks may also be left out.

FIG. 11 illustrates an example embodiment of an apparatus 1100, which may be an apparatus such as, or comprising, or comprised in, a user device. The user device may correspond to one of the user devices 100, 102 of FIG. 1. The user device may also be called a subscriber unit, mobile station, remote terminal, access terminal, user terminal, terminal device, or user equipment (UE).

The apparatus 1100 comprises at least one processor 1110. The at least one processor 1110 interprets computer program instructions and processes data. The at least one processor 1110 may comprise one or more programmable processors. The at least one processor 1110 may comprise programmable hardware with embedded firmware and may, alternatively or additionally, comprise one or more applicationspecific integrated circuits (ASICs).

The at least one processor 1110 is coupled to at least one memory 1120. The at least one processor is configured to read and write data to and from the at least one memory 1120. The at least one memory 1120 may comprise one or more memory units. The memory units may be volatile or non-volatile. It is to be noted that in some example embodiments there may be one or more units of non-volatile memory and one or more units of volatile memory or, alternatively, one or more units of non-volatile memory, or, alternatively, one or more units of volatile memory. Volatile memory may be for example random-access memory (RAM), dynamic random-access memory (DRAM) or synchronous dynamic random-access memory (SDRAM). Non-volatile memory may be for example read-only memory (ROM), programmable read-only memory (PROM), electronically erasable programmable read-only memory (EEPROM), flash memory, optical storage or magnetic storage. In general, memories may be referred to as non- transitory computer readable media. The at least one memory 1120 stores computer readable instructions that are executed by the at least one processor 1110 to perform one or more of the example embodiments described above. For example, non-volatile memory stores the computer readable instructions, and the at least one processor 1110 executes the instructions using volatile memory for temporary storage of data and/or instructions.

The computer readable instructions may have been pre-stored to the at least one memory 1120 or, alternatively or additionally, they may be received, by the apparatus, via an electromagnetic carrier signal and/or may be copied from a physical entity such as a computer program product. Execution of the computer readable instructions causes the apparatus 1100 to perform one or more of the functionalities described above.

In the context of this document, a “memory” or “computer-readable media” or “computer-readable medium” may be any non-transitory media or medium or means that can contain, store, communicate, propagate or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer.

The apparatus 1100 may further comprise, or be connected to, an input unit 1130. The input unit 1130 may comprise one or more interfaces for receiving input. The one or more interfaces may comprise for example one or more temperature, motion and/or orientation sensors, one or more cameras, one or more accelerometers, one or more microphones, one or more buttons and/or one or more touch detection units. Further, the input unit 1130 may comprise an interface to which external devices may connect to.

The apparatus 1100 may also comprise an output unit 1140. The output unit may comprise or be connected to one or more displays capable of rendering visual content, such as a light emitting diode (LED) display, a liquid crystal display (LCD) and/or a liquid crystal on silicon (LCoS) display. The output unit 1140 may further comprise one or more audio outputs. The one or more audio outputs may be for example loudspeakers.

The apparatus 1100 further comprises a connectivity unit 1150. The connectivity unit 1150 enables wireless connectivity to one or more external devices. The connectivity unit 1150 comprises at least one transmitter and at least one receiver that may be integrated to the apparatus 1100 or that the apparatus 1100 may be connected to. The at least one transmitter comprises at least one transmission antenna, and the at least one receiver comprises at least one receiving antenna. The connectivity unit 1150 may comprise an integrated circuit or a set of integrated circuits that provide the wireless communication capability for the apparatus 1100. Alternatively, the wireless connectivity may be a hardwired application-specific integrated circuit (ASIC). The connectivity unit 1150 may comprise one or more components, such as: power amplifier, digital front end (DFE), analog-to-digital converter (ADC), digital-to-analog converter (DAC), frequency converter, (de)modulator, and/or encoder/decoder circuitries, controlled by the corresponding controlling units.

It is to be noted that the apparatus 1100 may further comprise various components not illustrated in FIG. 11. The various components may be hardware components and/or software components.

The apparatus 1200 of FIG. 12 illustrates an example embodiment of an apparatus such as, or comprising, or comprised in, a network element of a wireless communication network. The network element may correspond to the access node 104 of FIG. 1. The network element may also be referred to, for example, as a network node, a radio access network (RAN) node, a NodeB, an eNB, a gNB, a base transceiver station (BTS), a base station, an NR base station, a 5G base station, an access node, an access point (AP), a relay node, a repeater, an integrated access and backhaul (1AB) node, an 1AB donor node, a distributed unit (DU), a central unit (CU), a baseband unit (BBU), a radio unit (RU), a radio head, a remote radio head (RRH), or a transmission and reception point (TRP).

The apparatus 1200 may comprise, for example, a circuitry or a chipset applicable for realizing one or more of the example embodiments described above. The apparatus 1200 may be an electronic device comprising one or more electronic circuitries. The apparatus 1200 may comprise a communication control circuitry 1210 such as at least one processor, and at least one memory 1220 storing instructions which, when executed by the at least one processor, cause the apparatus 1200 to carry out one or more of the example embodiments described above. Such instructions may, for example, include a computer program code (software) 1222 wherein the at least one memory and the computer program code (software) 1222 are configured, with the at least one processor, to cause the apparatus 1200 to carry out some of the example embodiments described above. Herein computer program code may in turn refer to instructions that cause the apparatus 1200 to perform one or more of the example embodiments described above. That is, the at least one processor and the at least one memory 1220 storing the instructions may cause said performance of the apparatus.

The processor is coupled to the memory 1220. The processor is configured to read and write data to and from the memory 1220. The memory 1220 may comprise one or more memory units. The memory units may be volatile or non-volatile. It is to be noted that in some example embodiments there may be one or more units of non-volatile memory and one or more units of volatile memory or, alternatively, one or more units of non-volatile memory, or, alternatively, one or more units of volatile memory. Volatile memory may be for example random-access memory (RAM), dynamic random-access memory (DRAM) or synchronous dynamic random-access memory (SDRAM). Nonvolatile memory may be for example read-only memory (ROM), programmable read-only memory (PROM), electronically erasable programmable read-only memory (EEPROM), flash memory, optical storage or magnetic storage. In general, memories may be referred to as non-transitory computer readable media. The memory 1220 stores computer readable instructions that are executed by the processor. For example, non-volatile memory stores the computer readable instructions and the processor executes the instructions using volatile memory for temporary storage of data and/or instructions.

The computer readable instructions may have been pre-stored to the memory 1220 or, alternatively or additionally, they may be received, by the apparatus, via an electromagnetic carrier signal and/or may be copied from a physical entity such as a computer program product. Execution of the computer readable instructions causes the apparatus 1200 to perform one or more of the functionalities described above.

The memory 1220 may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and/or removable memory. The memory may comprise a configuration database for storing configuration data. For example, the configuration database may store a current neighbour cell list, and, in some example embodiments, structures of the frames used in the detected neighbour cells.

The apparatus 1200 may further comprise a communication interface 1230 comprising hardware and/or software for realizing communication connectivity according to one or more communication protocols. The communication interface 1230 comprises at least one transmitter (Tx) and at least one receiver (Rx) that may be integrated to the apparatus 1200 or that the apparatus 1200 may be connected to. The communication interface 1230 may comprise one or more components, such as: power amplifier, digital front end (DFE), analog-to-digital converter (ADC), digital-to-analog converter (DAC), frequency converter, (de)modulator, and/or encoder/decoder circuitries, controlled by the corresponding controlling units.

The communication interface 1230 provides the apparatus with radio communication capabilities to communicate in the cellular communication system. The communication interface may, for example, provide a radio interface to one or more user devices. The apparatus 1200 may further comprise another interface towards a core network such as the network coordinator apparatus and/or to the access nodes of the cellular communication system.

The apparatus 1200 may further comprise a scheduler 1240 that is configured to allocate radio resources. The scheduler 1240 may be configured along with the communication control circuitry 1210 or it may be separately configured.

It is to be noted that the apparatus 1200 may further comprise various components not illustrated in FIG. 12. The various components may be hardware components and/or software components. As used in this application, the term “circuitry” may refer to one or more or all of the following: a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry); and b) combinations of hardware circuits and software, such as (as applicable): i) a combination of analog and/or digital hardware circuit(s) with software/firmware and ii) any portions of hardware processor(s) with software (including digital signal processor(s), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone, to perform various functions); and c) hardware circuit(s) and/or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (for example firmware) for operation, but the software may not be present when it is not needed for operation.

This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

The techniques and methods described herein may be implemented by various means. For example, these techniques may be implemented in hardware (one or more devices), firmware (one or more devices), software (one or more modules), or combinations thereof. For a hardware implementation, the apparatus(es) of example embodiments may be implemented within one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), graphics processing units (GPUs), processors, controllers, micro-controllers, microprocessors, other electronic units designed to perform the functions described herein, or a combination thereof. For firmware or software, the implementation can be carried out through modules of at least one chipset (for example procedures, functions, and so on) that perform the functions described herein. The software codes maybe stored in a memory unit and executed by processors. The memory unit may be implemented within the processor or externally to the processor. In the latter case, it can be communicatively coupled to the processor via various means, as is known in the art. Additionally, the components of the systems described herein may be rearranged and/or complemented by additional components in order to facilitate the achievements of the various aspects, etc., described with regard thereto, and they are not limited to the precise configurations set forth in the given figures, as will be appreciated by one skilled in the art. It will be obvious to a person skilled in the art that, as technology advances, the inventive concept may be implemented in various ways. The embodiments are not limited to the example embodiments described above, but may vary within the scope of the claims. Therefore, all words and expressions should be interpreted broadly, and they are intended to illustrate, not to restrict, the example embodiments.

Claims

1. An apparatus comprising at least one processor, and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to: receive a first set of data, wherein the first set of data comprises at least one subpacket of at least one file of a set of files; receive a set of identifiers and a mapping indicating an association of the set of identifiers to a subset of subpackets of the set of files; receive an indication for determining one or more identifiers associated with a second set of data to be transmitted over a plurality of overlapping data channels, wherein the one or more identifiers are comprised in the set of identifiers, and the second set of data comprises at least a part of one or more subpackets of the subset of subpackets; identify one or more data channels to be cancelled from the plurality of overlapping data channels, wherein the one or more data channels are identified based at least partly on the one or more identifiers; receive the plurality of overlapping data channels, wherein the plurality of overlapping data channels overlap in time and frequency; and cancel the one or more data channels of the plurality of overlapping data channels based at least partly on the first set of data.

2. The apparatus according to claim 1, wherein the indication comprises the one or more identifiers, and wherein an identifier of the one or more identifiers is associated with a single subpacket of the second set of data.

3. The apparatus according to claim 1, wherein the indication comprises the one or more identifiers, and wherein an identifier of the one or more identifiers is associated with a plurality of subpackets of the second set of data.

4. The apparatus according to any preceding claim, wherein the indication comprises a transport block index associated with the at least part of the one or more subpackets.

5. The apparatus according to any preceding claim, further comprising the apparatus being caused to: receive a first set of parameters for the plurality of overlapping data channels, wherein the first set of parameters comprises at least time and frequency domain resource allocations common for the plurality of overlapping data channels, wherein the plurality of overlapping data channels are received based on the first set of parameters.

6. The apparatus according to any preceding claim, further comprising the apparatus being caused to: decode a data channel of the plurality of overlapping data channels in response to cancelling the one or more data channels.

7. The apparatus according to claim 6, further comprising the apparatus being caused to: transmit a request for requesting one or more files from the set of files, wherein the requested one or more files are associated with at least one identifier of the one or more identifiers; and identify the data channel to be decoded, wherein the data channel is identified based at least partly on the at least one identifier associated with the requested one or more files, and the data channel to be decoded comprises one or more subpackets of the requested one or more files.

8. The apparatus according to any of claims 6-7, further comprising the apparatus being caused to: receive a second set of parameters for channel estimation of the data channel to be decoded, wherein the second set of parameters comprise at least one of: a demodulation reference signal index associated with the data channel to be decoded, a modulation and coding scheme index associated with the data channel to be decoded, and/or a data indicator associated with the data channel to be decoded.

9. The apparatus according to any of claims 1-7, further comprising the apparatus being caused to: receive a third set of parameters comprising at least one of: a demodulation reference signal index associated with the one or more data channels to be cancelled, and/or a modulation and coding scheme index associated with the one or more data channels to be cancelled, wherein the one or more data channels are cancelled based at least partly on the third set of parameters.

10. The apparatus according to any of claims 1-7, further comprising the apparatus being caused to: receive a fourth set of parameters comprising at least one of: one or more demodulation reference signal indexes associated with the plurality of overlapping data channels, one or more modulation and coding scheme indexes associated with the plurality of overlapping data channels, and/or one or more power control commands associated with the plurality of overlapping data channels, wherein the one or more data channels are cancelled based at least partly on the fourth set of parameters.

11. The apparatus according to any preceding claim, wherein the apparatus comprises, or is comprised in, a user device.

12. An apparatus comprising at least one processor, and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to: transmit, to one or more user devices, a first set of data comprising at least one subpacket of at least one file of a set of files; transmit, to the one or more user devices, a set of identifiers and a mapping indicating an association of the set of identifiers to a subset of subpackets of the set of files; transmit, to the one or more user devices, an indication for determining one or more identifiers associated with a second set of data to be transmitted over a plurality of overlapping data channels, wherein the one or more identifiers are comprised in the set of identifiers, and the second set of data comprises at least a part of one or more subpackets of the subset of subpackets; and transmit, to the one or more user devices, the plurality of overlapping data channels, wherein the plurality of overlapping data channels overlap in time and frequency.

13. The apparatus according to claim 12, wherein the indication comprises the one or more identifiers, and wherein an identifier of the one or more identifiers is associated with a single subpacket of the second set of data.

14. The apparatus according to claim 12, wherein the indication comprises the one or more identifiers, and wherein an identifier of the one or more identifiers is associated with a plurality of subpackets of the second set of data.

15. The apparatus according to any of claims 12-14, wherein the indication comprises a transport block index associated with the at least part of the one or more subpackets.

16. The apparatus according to any of claims 12-15, further comprising the apparatus being caused to: transmit, to the one or more user devices, a first set of parameters for the plurality of overlapping data channels, wherein the first set of parameters comprises at least one of: time and frequency domain resource allocations common for the plurality of overlapping data channels, wherein the plurality of overlapping data channels are transmitted based on the first set of parameters.

17. The apparatus according to any of claims 12-16, further comprising the apparatus being caused to: receive, from the one or more user devices, a request for requesting one or more files from the set of files, wherein the requested one or more files are associated with at least one identifier of the one or more identifiers, and at least one data channel of the plurality of overlapping data channels comprises one or more subpackets of the requested one or more files.

18. The apparatus according to claim 17, further comprising the apparatus being caused to: transmit a second set of parameters comprising at least one of: a demodulation reference signal index associated with the at least one data channel, a modulation and coding scheme index associated with the at least one data channel, and/or a data indicator associated with the at least one data channel.

19. The apparatus according to any of claims 12-17, further comprising the apparatus being caused to: transmit a third set of parameters comprising at least one of: a demodulation reference signal index per data channel of the plurality of overlapping data channels, and/or a modulation and coding scheme index per data channel of the plurality of overlapping data channels.

20. The apparatus according to any of claims 12-17, further comprising the apparatus being caused to: transmit a fourth set of parameters comprising at least one of: one or more demodulation reference signal indexes associated with the plurality of overlapping data channels, one or more modulation and coding scheme indexes associated with the plurality of overlapping data channels, and/or one or more power control commands associated with the plurality of overlapping data channels.

21. The apparatus according to any of claims 12-20, wherein the indication is transmitted separately per user device of the one or more user devices.

22. The apparatus according to any of claims 12-20, wherein the indication is transmitted by groupcasting the indication to a group of user devices comprising at least the one or more user devices.

23. The apparatus according to any of claims 12-22, wherein the apparatus comprises, or is comprised in, a network element of a wireless communication network.

24. An apparatus comprising means for: receiving a first set of data, wherein the first set of data comprises at least one subpacket of at least one file of a set of files; receiving a set of identifiers and a mapping indicating an association of the set of identifiers to a subset of subpackets of the set of files; receiving an indication for determining one or more identifiers associated with a second set of data to be transmitted over a plurality of overlapping data channels, wherein the one or more identifiers are comprised in the set of identifiers, and the second set of data comprises at least a part of one or more subpackets of the subset of subpackets; identifying one or more data channels to be cancelled from the plurality of overlapping data channels, wherein the one or more data channels are identified based at least partly on the one or more identifiers; receiving the plurality of overlapping data channels, wherein the plurality of overlapping data channels overlap in time and frequency; and cancelling the one or more data channels of the plurality of overlapping data channels based at least partly on the first set of data.

25. An apparatus comprising means for: transmitting, to one or more user devices, a first set of data comprising at least one subpacket of at least one file of a set of files; transmitting, to the one or more user devices, a set of identifiers and a mapping indicating an association of the set of identifiers to a subset of subpackets of the set of files; transmitting, to the one or more user devices, an indication for determining one or more identifiers associated with a second set of data to be transmitted over a plurality of overlapping data channels, wherein the one or more identifiers are comprised in the set of identifiers, and the second set of data comprises at least a part of one or more subpackets of the subset of subpackets; and transmitting, to the one or more user devices, the plurality of overlapping data channels, wherein the plurality of overlapping data channels overlap in time and frequency.

26. A method comprising: receiving a first set of data, wherein the first set of data comprises at least one subpacket of at least one file of a set of files; receiving a set of identifiers and a mapping indicating an association of the set of identifiers to a subset of subpackets of the set of files; receiving an indication for determining one or more identifiers associated with a second set of data to be transmitted over a plurality of overlapping data channels, wherein the one or more identifiers are comprised in the set of identifiers, and the second set of data comprises at least a part of one or more subpackets of the subset of subpackets; identifying one or more data channels to be cancelled from the plurality of overlapping data channels, wherein the one or more data channels are identified based at least partly on the one or more identifiers; receiving the plurality of overlapping data channels, wherein the plurality of overlapping data channels overlap in time and frequency; and cancelling the one or more data channels of the plurality of overlapping data channels based at least partly on the first set of data.

27. A method comprising: transmitting, to one or more user devices, a first set of data comprising at least one subpacket of at least one file of a set of files; transmitting, to the one or more user devices, a set of identifiers and a mapping indicating an association of the set of identifiers to a subset of subpackets of the set of files; transmitting, to the one or more user devices, an indication for determining one or more identifiers associated with a second set of data to be transmitted over a plurality of overlapping data channels, wherein the one or more identifiers are comprised in the set of identifiers, and the second set of data comprises at least a part of one or more subpackets of the subset of subpackets; and transmitting, to the one or more user devices, the plurality of overlapping data channels, wherein the plurality of overlapping data channels overlap in time and frequency.

28. A computer program comprising instructions for causing an apparatus to perform at least the following: receiving a first set of data, wherein the first set of data comprises at least one subpacket of at least one file of a set of files; receiving a set of identifiers and a mapping indicating an association of the set of identifiers to a subset of subpackets of the set of files; receiving an indication for determining one or more identifiers associated with a second set of data to be transmitted over a plurality of overlapping data channels, wherein the one or more identifiers are comprised in the set of identifiers, and the second set of data comprises at least a part of one or more subpackets of the subset of subpackets; identifying one or more data channels to be cancelled from the plurality of overlapping data channels, wherein the one or more data channels are identified based at least partly on the one or more identifiers; receiving the plurality of overlapping data channels, wherein the plurality of overlapping data channels overlap in time and frequency; and cancelling the one or more data channels of the plurality of overlapping data channels based at least partly on the first set of data.

29. A computer program comprising instructions for causing an apparatus to perform at least the following: transmitting, to one or more user devices, a first set of data comprising at least one subpacket of at least one file of a set of files; transmitting, to the one or more user devices, a set of identifiers and a mapping indicating an association of the set of identifiers to a subset of subpackets of the set of files; transmitting, to the one or more user devices, an indication for determining one or more identifiers associated with a second set of data to be transmitted over a plurality of overlapping data channels, wherein the one or more identifiers are comprised in the set of identifiers, and the second set of data comprises at least a part of one or more subpackets of the subset of subpackets; and transmitting, to the one or more user devices, the plurality of overlapping data channels, wherein the plurality of overlapping data channels overlap in time and frequency.