NETWORK

TECHNICAL FIELD

The present disclosure relates to a Relay Station, in particular a Relay Node or a User Equipment (UE) with relay function, and a method for relaying data along a relay path in a wireless network. The disclosure further relates to a central scheduler, in particular a base station, for scheduling such Relay Stations. Particularly, the disclosure relates to a low- latency Relay for enhancing reliable mesh networking.

BACKGROUND

One of the unique features of 5G wireless communication beyond 4G is the Ultra-Reliable and Low-Latency Communication (URLLC). Introducing Mesh networking with multi-hop and node cooperation into 5G can potentially give significant enhancement to communication reliability. Figure 1 illustrates mesh relay in factory scenario. In Fig. 1 , a base station 1 10 is located at one corner of a factory 100 while two UEs 140, 150 are located at different locations of the factory 100. Two UEs / relay nodes 120, 130 located between the base station 1 10 and the two UEs 140, 150 are used to relay data from the base station to the UEs 140, 150 and vice versa. For example, in the scenario depicted in Fig. 1 , a first relay path 1 1 1 , 121 is used to transmit data from base station 1 10 via first relay node 120 to UE 140 (serving as destination node); a second relay path 1 12, 131 is used to transmit data from base station 1 10 via second relay node 130 to UE 140; a third relay path 151 , 132 is used to receive data from UE 150 (serving as source node) via second relay node

130 to base station 1 10 (serving as destination node). Figure 1 shows that the multi-hop relay can mitigate the channel blockage by machineries and provide redundancy with multiple hops. However, the multi-hop transmission among nodes can lead to large increase of communication latency.

Figure 2 illustrates the problem of conventional Mesh Networking 200 in terms of latency. A Mesh/Relay 213 should support both requirements defined in current 5G standardization, Ultra Reliable 21 1 and Ultra Low Latency 212, also subsumed under the term 5G URLLC 210. Ultra-Reliable and Low-Latency Communication (URLLC) 210 is key for supporting mission critical vertical industries, e.g. Industrial Automation, C-V2X. According to current requirements, Ultra Reliable 21 1 is defined as an error probability < 10 ⁵ , while Ultra Low- latency 212 is defined as an end-to-end latency < 1 ms. In 5G, a new design of Integrated Access & Backhaul (IAB) is defined to enable flexible and dense deployment of NR (New Radio) cells without densifying the transport network proportionally. TDM/FDM/SDM of IAB links are considered. According to the current 5G specification, this“does not exclude full duplex solutions to be studied”.

For reliability enhancement, relaying / mesh networking 213 becomes highly interesting to solve coverage and deployment problems. According to current 5G standardization, a single or a few base stations (BS) cannot guarantee coverage in complicated channel environments such as a factory (see Figure 1 for example) or dense urban area, since small- scale fading or shadowing of several dB renders any robust modulation/coding/diversity scheme inefficient. Relaying and mesh networking can alleviate this problem due to the following characteristics: 1 ) mitigating channel blockage by opening redundant propagation paths; 2) improving capacity by increasing MIMO rank and frequency reuse; 3) enhancing reliability by combining relay path and source path; 4) suitable for the communications based on both cellular link and sidelink.

However, conventional relaying increases latency due to half-duplex constraint and processing delay as latency T _delay increases with the number of hops N _hop according to the following relation: T _delay = N _hop (T _frame + where T _frame denotes the frame duration and T _proc denotes the frame processing time. Shortly speaking, in conventional Mesh networking with half-duplex constraint, with one more hop, the delay is increased by at least one time slot.

In order to describe the invention in detail, the following terms, abbreviations and notations will be used:

SICCI: Self-Interference Cancellation Capability Information

Cl: Channel Information

RNI: Relaying Notification Information

RSI: Relay Scheduling Information

DL: Downlink

UL: Uplink

SL: Sidelink

URLLC: Ultra-Reliable Low-Latency Communication

IAB: Integrated Access and Backhaul

TDM: Time Division Multiple Access FDM: Frequency Division Multiple Access

SDM: Space Division Multiple Access

P2P: Point-to-Point

Rx: Reception

Tx: Transmission

OFDM: Orthogonal Frequency Division Multiplex

E2E: End-to-End

EF: Equalize and Forward

AF: Amplify and Forward

FD: Full duplex

CC-FD: co-channel Full duplex relaying

AC-FD: adjacent channel Full duplex relaying

SIC: Self-interference cancellation

MIMO: Multiple Input Multiple Output

RB: Resource block

GP: Guard period

RS: Reference signal

RNI: Relay Node Identification

SFGI: Slot Format Group Indicator

SUMMARY

It is the object of the invention to provide techniques for solving the above described problems, i.e. to improve relaying in terms of reliability and latency in order to fulfil the 5G requirements of Ultra-Reliable and Low-Latency Communication (URLLC) as shown in Fig. 2.

This object is achieved by the features of the independent claims. Further implementation forms are apparent from the dependent claims, the description and the figures.

Figure 3 gives an overview 300 of the core ideas of this disclosure. A new type of relay node or UE with simultaneous relay function (Low-Latency Inband Relay Node 310) is introduced, targeting at low latency within the same time slot based on the awareness of Self- Interference Cancellation Capability Information (SICCI). This new type of relay node or UE with relay function provides the following features: Inband full-duplex with Equalize & Forward (EF) (optionally with precoding after equalization) or Amplify & Forward (AF) providing simultaneous relaying in the same or neighboring Resource Block (RB) within the same time slot; Flexible relay node and path selection based on channel measurement between UEs and between UE and BS; and supporting simultaneous Transmission (Tx) and Reception (Rx) on the same antenna. A new type of signaling (Signaling Enhancement 340), e.g. as described below with respect to Figures 7 and 8, is introduced providing SICCI, i.e. self-interference levels among different frequency sub-channel and spatial beams, RNI (Relay Notification Information) and RSI (Relay Scheduling Information). A New frame structure design 320, e.g. as described below with respect to Figures 9 and 13-15, is introduced for full-duplex relaying nodes with OFDM symbol level shifting within one time slot and carrying RNI in leading symbol(s). Three options of scheduled, voluntary and hybrid relaying configuration procedures 330 are presented based on SICCI, RNI, RSI and channel information (Cl), e.g. as described below with respect to Figures 10-12.

The Low-Latency Inband Relay Node 310 is designed for using full-duplex capability, simultaneous relaying in the same or neighboring frequency sub-channel (e.g. RB) within the same time slot. It is further designed for forwarding delay much smaller than the L1 frame length (with Equalize(-Precode) & Forward or Amplify & Forward). The relay node 310 can be either a dedicated relay node or a new type of UE with relay function. The supported number of relay hops is greater than 1.

The new Frame Structure Design 320 allows OFDM symbol level shifting within one time slot for guaranteeing low latency. Leading symbol(s) are used for signaling RNI.

The Signaling enhancement 340 is designed to provide Information exchange for optimizing relay, i.e. exchange of SICCI additionally to Cl; Signaling for coordinating the relaying operation using RNI and RSI. The Relay node utilizes the delay caused by relay processing for signaling RNI.

The Scheduled or Voluntary or Hybrid Relay Configuration 330 is designed for selecting relaying channel based on SICCI & Cl & CoS (requirements on delay & throughput), Scheduling with RSI and Notification with RNI.

In Mesh + Co-/Adjacent-Channel Full Duplex (FD) scenario, signaling enhancement 340 provides a new type of signaling “Self-Interference Cancellation Capability Information (SICCI)” that allows for creating low-latency & reliable relaying path by applying (a) SICCI dimensions: Frequency sub-channel, (Tx and Rx beams, Tx Power) and (b) Considering SICCI and Channel Information (Cl) for optimal resource allocation (in time, frequency, space/beam). The new frame structure design 320 enables to facilitate E2E (end-to-end) multi-hop relay path within one single time slot, instead of over multiple time slots (a) OFDM symbol level shifting allows for EF with/without channel information. Note that simulation shows much better performance of EF over AF. (b) The new type of signaling “Relay Notification Information (RNI)” is transmitted utilizing the short delay time before relay transmission, which itself is generated by the symbol shifting.

A flexible resource allocation method of full duplex relaying Co-Channel Full Duplex (CC- FD) and Adjacent Channel (AC-FD) is introduced. In AC-FD, adjacent RBs are allocated for simultaneous Tx and Rx, while CC-FD supports allocation of the same RB for simultaneous Tx and Rx.

In the Co-channel Full Duplex scenario, the ideal Full Duplex with simultaneous Tx/Rx even on the same channel can be achieved, however at very high Self-Interference Cancellation (SIC) requirement such as >120dB at high cost, which becomes even more challenging with MIMO.

In the Adjacent-channel Full Duplex scenario greatly relaxed SIC requirement can be achieved thanks to inherent sidelobe suppression, however, at the cost of higher consumption of resources than for the CC-FD scenario, but not more than for the conventional relay. Besides, with AC-FD, signals from multiple up-stream nodes can be combined for reliability enhancement at the destination.

The maturing full-duplex radio technology can be utilized, considering practical relaxation of full-duplex requirement: With SIC, latency reduction yield by simultaneous Tx/Rx with flexible spectral band allocation becomes feasible.

In the following, techniques for relaying based on sidelink transmission and based on Uu link transmission are described. The 4G and 5G system includes two radio interfaces:

A) The cellular interface, named Uu, supports UE to Base Station (BS) communications.

B) The sidelink interface supports Device-to-Device (D2D) direct communication, which was introduced for the first time under Release 12 for public safety, and includes two modes of operation, that are mode 1 and mode 2.

Release 14 introduces two new communication modes, that are mode 3 and 4, which were specifically designed for V2V communications. In mode 3, the cellular network selects and manages the radio resources used by the vehicles for their direct V2V communications. In mode 4, the vehicles autonomously select radio resources for their direct V2V communications. In contrast, mode 4 can operate without cellular coverage, and is thus considered the baseline V2V mode, since safety applications cannot depend on the availability of cellular coverage. Mode 4 includes a distributed scheduling scheme for vehicles to select their radio resources. Mode 4 further includes the support for distributed congestion control. Relaying techniques as described in the following may be applied in mode 1 and 2 D2D sidelink communications as well as in mode 3 and 4 V2X sidelink communications.

According to a first aspect, the invention relates to a relay station, in particular a relay node or a User Equipment, UE, with relay function, for relaying data along a relay path in a wireless network, wherein the relay station is configured to: receive a data frame in one or more frequency sub-channels within a time slot, and forward the data frame in the same or neighboring frequency sub-channels within the same time slot depending on Self- Interference Cancellation Capability Information, SICCI, wherein the SICCI indicates a level of self-interference across the frequency sub-channels for the relay station as well as for a number of other relay stations within the relay path.

This relay station provides the advantage of improved relaying in terms of reliability and latency. By using such relay station, the 5G requirements of Ultra-Reliable and Low-Latency Communication (URLLC) may be fulfilled. The low latency can be achieved by using full duplex transmission within the same time slot based on the awareness of SICCI. This new type of relay node or UE with relay function provides the following advantages: Inband full- duplex with EF/AF providing simultaneous relaying in the same or neighboring RB within the same time slot; Flexible relay node and path selection based on channel measurement between UEs and between UE and BS; and supporting simultaneous Tx + Rx on the same antenna.

As defined above, Self-Interference Cancellation Capability Information, SICCI, also referred to as Self-Interference Rejection Capability Information, indicates a level of selfinterference across the frequency sub-channels for the relay station as well as for a number of other relay stations within the relay path. SICCI can be determined during production of the relay station or during a bootstrap process when booting the relay station or even during operation of the relay station. Determining SICCI is implementation dependent. The relay node can be a UE configured as relay node or a base station or any other network node configured as a relay node. The relay path can include multiple relay stations introducing multi-hop relaying. The relay station is designed to fulfill Ultra Low Latency requirements as defined in 5G that are below 1 ms. In one implementation, the number of other relay stations can be zero. Then, there is only one relay station in the relay path. The relay path is spanned between a source node and a destination node.

In an exemplary implementation form of the relay station, the SICCI comprises at least one of the following: the ratio(s) of the transmitted signal power to the received leakage power for at least a pair of transmitting and receiving frequency sub-channels,

a node index for uniquely identifying the relay station within the relay path,

a frequency sub-channel index for uniquely identifying a frequency sub-channel used by the relay station, and a beam pair of transmit beam index and receive beam index for which beam pair the ratio of transmit signal to receive leakage power applies.

This provides the advantage that the interference environment of each pair of transmitting and receiving frequency sub-channels can be precisely specified, and based on this information, the relay process can be optimally designed.

Receive leakage is the leakage into other sub-channels (or into the same sub-channel) when the relay station transmits on a specific sub-channel. The transmit signal and receive leakage power can be measured per subchannel. The ratio of transmit signal to receive leakage power can be defined for any pair of neighboring subchannels but also for the same subchannel. A frequency subchannel generally defines a subchannel used by the relay station. The frequency subchannel may be used by the relay station for transmission or reception. The relay station may be further configured to: forward the data frame based on Channel Information, Cl, wherein the Cl indicates a quality of a channel between any pair of relay stations or between relay stations and base station and may be calculated for each frequency sub-channel.

In an exemplary implementation form of the relay station, the relay station is configured to: receive and forward the data frame simultaneously within the same time slot.

This provides the advantage that by simultaneous reception and forwarding, latency times can be significantly reduced.

The relay station may be configured to receive and forward the data frame in a full-duplex mode by overlap in time and frequency. For full-duplex mode multi hop relaying, latency can be below symbol level: e.g. EF at OFDM symbol level, AF at sample level. In an exemplary implementation form of the relay station, the relay station is configured to support simultaneous transmission with other relay stations within the same time slot.

This provides the advantage that by simultaneous transmission with other relay stations, latency times for the full relay path can be significantly reduced, which results in latency- efficient data transmission.

In an exemplary implementation form of the relay station, the relay station is configured to transmit Relaying Notification Information, RNI, while processing the current received data frame, wherein the RNI comprises at least one of the following: the relay station’s reception resource from its upstream nodes, in particular frequency sub-channel and/or time slot, the relay station’s upstream nodes, the relay station’s downstream nodes, the relay station’s transmission resource, in particular relaying slot format, frequency channel, beam index, the relay station’s modulation and coding scheme.

This provides the advantage that RNI inform all the downstream nodes on the current configuration of the relay path for adjusting their relay processing. Besides the RNI can assist other nodes for coordinating the resource usage and deciding whether to perform voluntary cooperative relaying with the relay station.

A predetermined relay path is composed of one source node, one destination node and one or multiple relay nodes. From the perspective of one relay node, the upstream nodes means the source node and/or other relay nodes from which the current relay node receives signal, along the transmission direction of the relay path. While the downstream nodes means the destination node and/or other relay node to which the current node transmits signal, along the transmission direction of the relay path.

The relay station’s reception resource are resources on which the relay station receives data. The relay station’s transmission resource are resources on which the relay station transmits data.

In an exemplary implementation form of the relay station, the relay station is configured to receive Relay Scheduling Information, RSI, wherein the RSI comprises at least one of the following: identities of the relay station and other relay stations within the relay path, each relay station’s transmission resource, in particular relaying slot format and/or frequency channel, each relay station’s transmission power, each relay station’s transmission beam, each relay station’s modulation and coding scheme. In an exemplary implementation form of the relay station, the data frame is arranged according to a predetermined relay time slot format comprising a relay control section, a relay payload section and a variable blank section.

The blank section provides the advantage that a common relay time slot format can be specified for all relay stations of the relay path as well as for destination and source nodes which facilitates the accommodation of the relay time delay.

In an exemplary implementation form of the relay station, the relay station is configured to shift the relay payload section of a received data frame by a specific number of symbols in time and to fill-up leading symbols before the relay payload section with the relay control section and ending symbols after the relay payload section with the blank section.

This provides the advantage that after each relay station, the data frame is shifted in a known manner. This allows performing data relaying even in long relay paths consisting of multiple relay stations.

In an exemplary implementation form of the relay station, the relay payload section of a data frame comprises transmission symbols for transmission of downlink, uplink and/or sidelink signals, wherein the blank section comprises blank symbols for accommodating symbol- level relaying time shift and Guard Period to compensate near-far effect, and

wherein the relay control section comprises relay control signals carrying Relaying Notification Information, RNI, preamble and/or reference signal.

This provides the advantage that different data links can be implemented by such relay station, e.g. data links like downlink, uplink and sidelink.

Downlink, uplink and sidelink signals are general terms for these signals. They also include relayed versions of these signals, i.e. relayed DL, relayed UL and relayed SL signals.

In an exemplary implementation form of the relay station, the relay station is configured to receive an assignment to a particular relay time slot format that is common to a group of relay stations, in particular the group of relay stations along the relay path, wherein the particular relay time slot format is indicated by a relay time Slot Format Group Indicator (SFGI). This provides the advantage that relaying can be efficiently performed by a group of relay stations when each relay station knows the assignment to the particular relay time slot format of the group.

In an exemplary implementation form of the relay station, the relay payload section for a relay station transmitting on sidelink is filled with sidelink symbols; and the relay payload section for a relay station transmitting on Uu link comprises a section of downlink symbols and a section of uplink symbols which are separated by one or more blank symbols.

This provides the advantage that the relay station can be flexible implemented for sidelink transmission as well as for Uu link transmission.

In an exemplary implementation form of the relay station, the relay station is configured to: determine the SICCI and/or Channel Information, Cl, of the relay path and transmit the SICCI and/or the Cl to a central scheduler, in particular a base station and/or exchange the SICCI and/or Cl between nodes of the relay path.

This provides the advantage that by transmitting the SICCI and optionally the Cl to a central scheduler can improve the scheduling strategy of the central scheduler and hence improve relaying of the relay station scheduled by the central scheduler.

In an exemplary implementation form of the relay station, the relay station is configured to receive Relay Scheduling Information, RSI, from a central scheduler, in particular a base station, and schedule data relaying and adjust resources based on the RSI.

This provides the advantage that relay transmission can be improved when receiving scheduling information from a central scheduler.

In an exemplary implementation form of the relay station, the RSI is based on Quality of Service requirements, in particular delay and throughput requirements, of the relay path.

This provides the advantage that the relay path can be optimally adjusted by exploiting the QoS requirements.

In an exemplary implementation form of the relay station, the relay station is configured to receive Relaying Notification Information, RNI, from other relay nodes, the RNI notifying the configured downstream relay nodes or other voluntary nodes for assisting the relay station in data relaying.

This provides the advantage that by including voluntary relay nodes, relay processing can be significantly improved with respect to reliability and latency.

In an exemplary implementation form of the relay station, the relay station comprises a processor, configured to process the received data frame based on one of the following schemes: Amplify & Forward, Amplify, Construct & Forward, Equalize & Forward, Equalize- Precode & Forward, Decode & Forward.

This provides the advantage that relay processing can be flexible switched between these schemes allowing to increase or decrease the performance of relaying in balance with the latency of the relay path.

According to a second aspect, the invention relates to a method for relaying data along a relay path in a wireless network, wherein the method comprises: receiving a data frame, by a relay station, in one or more frequency sub-channels within a time slot, and forwarding the data frame, by the relay station, in the same or neighboring frequency sub-channels within the same time slot dependent on Self-Interference Information, SICCI, wherein the SICCI indicates a level of self-interference across the frequency sub-channels for the relay station as well as for a number of other relay stations within the relay path.

This method provides the advantage of improved relaying in terms of reliability and latency. By using such method for relaying data along a relay path in a wireless network, the 5G requirements of Ultra-Reliable and Low-Latency Communication (URLLC) may be fulfilled. The low latency can be achieved by using full duplex transmission within the same time slot based on the awareness of SICCI. This new type of relay node or UE with relay function provides the following advantages: Inband full-duplex with EF/AF providing simultaneous relaying in the same or neighboring RB within the same time slot; Flexible relay node and path selection based on channel measurement between UEs and between UE and BS; and supporting simultaneous Tx + Rx on the same antenna.

According to a third aspect, the invention relates to a central scheduler, in particular a base station, for scheduling at least one relay station, in particular a relay node or a User Equipment, UE, with relay function, for relaying data along a relay path in a wireless network, wherein the relay station is configured to receive a data frame in one or more frequency sub-channels within a time slot and forward the data frame in the same or neighboring frequency sub-channels within the same time slot, wherein the central scheduler is configured to: receive Self-Interference Cancellation Capability Information, SICCI , from the at least one relay station, wherein the SICCI indicates a level of selfinterference across the frequency sub-channels for the at least one relay station and a number of other relay stations within the relay path, and schedule data relaying of the at least one relay station based on the SICCI.

Such a central scheduler provides the advantage of improved scheduling the relay stations in terms of reliability and latency. By using such a central scheduler, the 5G requirements of Ultra-Reliable and Low-Latency Communication (URLLC) may be fulfilled. The low latency can be achieved by using full duplex transmission within the same time slot based on the awareness of SICCI. This scheduling provides the following advantages: Inband full- duplex with EF/AF providing simultaneous relaying in the same or neighboring RB within the same time slot; Flexible relay node and path selection based on channel measurement between UEs and between UE and BS; and supporting simultaneous Tx + Rx on the same antenna.

The central scheduler may be further configured to schedule data relaying of the at least one relay station based on Channel Information, Cl, wherein the Cl indicates a quality of a channel between any pair of relay stations or between relay stations and base station, and may be calculated for each frequency sub-channel.

In an exemplary implementation form of the central scheduler, the SICCI comprises at least one of the following: a ratio of transmit signal to receive leakage power for at least one subchannel, a node index for uniquely identifying the relay station within the relay path, a frequency sub-channel index for uniquely identifying a frequency sub-channel used by the relay station, and a beam pair of transmit beam index and receive beam index for which beam pair the ratio of transmit signal to receive leakage power applies.

This provides the advantage that the interference environment of each pair of transmitting and receiving frequency sub-channels can be precisely specified and based on this information, relay transmission can be optimally designed.

In an exemplary implementation form of the central scheduler, the central scheduler is configured to schedule data relaying of the at least one relay station based on Relay Scheduling Information, RSI, wherein the RSI comprises at least one of the following: identities of the relay station and other relay stations within the relay path,

each relay station’s transmission resource, in particular relaying slot format and/or frequency channel, each relay station’s transmission power, each relay station’s transmission beam, each relay station’s modulation and coding scheme.

This provides the advantage that RSI received from other nodes may help the central scheduler to schedule the relay transmission, in particular for deciding which of the relay stations to utilize in the relay path.

According to a fourth aspect, the invention relates to a computer program product including computer executable code or computer executable instructions that, when executed, causes at least one computer to execute the method according to the second aspect. Such a computer program product may include a non-transient readable storage medium storing program code thereon for use by a processor, the program code comprising instructions for performing the methods or the computing blocks as described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

Further embodiments of the invention will be described with respect to the following figures, in which:

Fig. 1 shows a 3-dimensional diagram of a factory 100 comprising a mesh relay between base station 1 10 and UEs 140, 150;

Fig. 2 shows a schematic diagram illustrating the problem of conventional Mesh Networking 200 in terms of latency and reliability;

Fig. 3 shows a schematic block diagram 300 illustrating the core ideas of this disclosure;

Fig. 4 shows a schematic diagram of an exemplary relay path 400 in a wireless network including a source node 410, two relay nodes 420, 430 and a destination node 440 according to the disclosure;

Fig. 5a shows a schematic diagram of exemplary time-frequency resources 500a that may be applied for a conventional Mesh/Relay; Fig. 5b shows a schematic diagram of exemplary time-frequency resources 500b that may be applied for Full-Duplex Enabled Relaying according to the disclosure;

Fig. 6 shows a schematic diagram 600 illustrating Self-Interference Cancellation Capability Information (SICCI) 610 and Channel Information (Cl) 620 according to the disclosure;

Fig. 7 shows a schematic diagram 700 illustrating Self-Interference Cancellation Capability Information (SICCI) 610 according to the disclosure in more detail;

Fig. 8 shows a schematic diagram illustrating Relaying Notification Information (RNI) 810 and Relay Scheduling Information (RSI) 820 according to the disclosure in a detailed representation;

Fig. 9 shows a schematic diagram of the new relaying frame format 900 according to the disclosure;

Fig. 10 shows an exemplary message sequence chart 1000 illustrating scheduled relaying nodes and resource selection (option 1 ) according to the disclosure;

Fig. 1 1 shows an exemplary message sequence chart 1 100 illustrating voluntary relaying nodes and resource selection (option 2) according to the disclosure;

Fig. 12 shows an exemplary message sequence chart 1200 illustrating hybrid (scheduled and voluntary) relaying nodes and resource selection (option 3) according to the disclosure;

Fig. 13 shows a schematic diagram illustrating an exemplary 5G NR Low-Latency Full- Duplex Relaying slot format 1300 for the Sidelink according to the disclosure;

Fig. 14 shows a schematic diagram illustrating an exemplary 5G NR Low-Latency Full- Duplex Relaying slot format 1400 for the Uu link according to the disclosure;

Fig. 15 shows a schematic diagram illustrating the current r14 LTE-V2X sidelink frame structure 1501 and an enhancement 1502 with relaying with equalize (precode) and forward according to the disclosure; and

Fig. 16 shows a schematic diagram illustrating a method 1600 for relaying data along a relay path in a wireless network according to the disclosure. DETAILED DESCRIPTION OF EMBODIMENTS

In the following detailed description, reference is made to the accompanying drawings, which form a part thereof, and in which is shown by way of illustration specific aspects in which the disclosure may be practiced. It is understood that other aspects may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims. It is understood that comments made in connection with a described method may also hold true for a corresponding device or system configured to perform the method and vice versa. For example, if a specific method step is described, a corresponding device may include a unit to perform the described method step, even if such unit is not explicitly described or illustrated in the figures. Further, it is understood that the features of the various exemplary aspects described herein may be combined with each other, unless specifically noted otherwise.

The described devices may include integrated circuits and/or passives and may be manufactured according to various technologies. For example, the circuits may be designed as logic integrated circuits, analog integrated circuits, mixed signal integrated circuits, optical circuits, memory circuits and/or integrated passives.

The devices and systems described herein may include processors or processing devices, memories and transceivers, i.e. transmitters and/or receivers. In the following description, the term“processor” or“processing device” describes any device that can be utilized for processing specific tasks (or blocks or steps). A processor or processing device can be a single processor or a multi-core processor or can include a set of processors or can include means for processing. A processor or processing device can process software or firmware or applications etc.

Fig. 4 shows a schematic diagram of an exemplary relay path 400 in a wireless network including a source node 410, two relay nodes 420, 430 and a destination node 440 according to the disclosure. Figure 4 shows the scenario of relay node simultaneous transmission and reception (Tx & Rx), at the same or neighboring frequency channels. Relay 1 (420) and 2 (430) forward simultaneously with source 410; only a slight time shift 401 is applied. One relay node 420, 430 can process and relay multiple or all upstream nodes’ signals. The source node 410, e.g. base station 1 10 as described in Fig. 1 , transmits data 41 1 and simultaneously receives data 412, 413, 414, e.g. from Relay nodes 420, 430 or destination node 440. First relay node 420, e.g. UE/Relay 120 or UE/Relay 130 as depicted in Fig. 1 transmits data 421 and simultaneously receives data 422, 423, e.g. from Relay node 430 or destination node 440. Second relay node 430, e.g. UE/Relay 130 when coupled to UE/Relay 120 as depicted in Fig. 1 transmits data 431 and simultaneously receives data 432, e.g. from destination node 440.

In the relay path 400 in a wireless network shown in Fig. 4, relay station 420 (or any relay node or UE with relay function is designed for relaying data along the relay path 400. The relay station 120 is configured to receive a data frame 422 in one or more frequency subchannels 602, e.g. as shown in Fig. 6, within a time slot 402. The relay station 120 is further configured to forward the data frame 423 in the same or neighboring frequency subchannels 602 within the same time slot 402 depending on Self-Interference Cancellation Capability Information, SICCI 610, e.g. as shown below with respect to Fig. 6. The SICCI 610 indicates a level of self-interference across the frequency sub-channels 602 for the relay station 420 as well as for a number of other relay stations 430, 601 within the relay path 400.

As defined above, Self-Interference Cancellation Capability Information, SICCI, also referred to as Self- Interfere nee Rejection Capability Information indicates a level of selfinterference across the frequency sub-channels for the relay station as well as for a number of other relay stations within the relay path. SICCI can be determined during production of the relay station or during a bootstrap process when booting the relay station or even during operation of the relay station. Determining SICCI is implementation dependent. The relay node can be a UE configured as relay node or a base station or any other network node configured as a relay node. The relay path can include multiple relay stations introducing multi-hop relaying. The relay station is designed to fulfill Ultra Low Latency requirements as defined in 5G that are below 1 ms. In one implementation, the number of other relay stations can be zero. Then, there is only one relay station in the relay path. The relay path is spanned between a source node and a destination node.

The SICCI 610 may include one or any combination of the following parameters as described below with respect to Figure 6 in more detail: ratios of transmitted signal power to received leakage power 61 1 for at least a pair of transmitting and receiving frequency sub-channels, a node index 612 for uniquely identifying the relay station 420 within the relay path 400, a frequency sub-channel index 613a, 613b for uniquely identifying a frequency sub-channel (Tx and Rx components) used by the relay station 420, and a beam pair of transmit beam index 614 and receive beam index 615 for which beam pair a ratio of transmitted signal power to received leakage power applies. Tx subchannel index 613a is used to identify Tx subchannel, while Rx subchannel index 613b is used to identify Rx subchannel.

Receive leakage is the leakage into other sub-channels (or into the same sub-channel) when the relay station transmits on a specific sub-channel. The transmit signal and receive leakage power can be measured per subchannel. The ratio of transmit signal to receive leakage power can be defined for any pair of neighboring subchannels but also for the same subchannel. A frequency subchannel generally defines a subchannel used by the relay station. The frequency subchannel may be used by the relay station for transmission or reception. The relay station may be further configured to: forward the data frame based on Channel Information, Cl, wherein the Cl indicates a quality of a channel between any pair of relay stations or between relay stations and base station for each frequency sub-channel.

The relay station 420 is configured to receive and forward the data frame 422, 423 simultaneously within the same time slot 402. The relay station 420 is further configured to support simultaneous transmission 421 , 431 with other relay stations, e.g. relay station 430, within the same time slot 402.

The relay station 420 is configured to transmit Relaying Notification Information (RNI), e.g. RNI 810 as described below with respect to Fig. 8 in more detail, while processing the received data frame 422. The RNI 810 may comprises one or any combination of the following parameters: the relay station’s 420 reception resource from its upstream nodes 410, in particular frequency sub-channel and/or time slot, the relay station’s 420 upstream nodes, e.g. source node 410, the relay station’s 420 downstream nodes, e.g. relay node 430 and/or destination node 440, the relay station’s 420 transmission resource, in particular relaying slot format, frequency channel, beam index, the relay station’s 420 modulation and coding scheme.

The relay station may be configured to: receive and forward the data frame in a full-duplex mode by overlap in time and frequency. For full-duplex mode multi hop relaying, latency can be below symbol level: e.g. Equalize&Forward (EF) at symbol level, Amplify&Forward (AF) at sample level.

A predetermined relay path is composed of one source node, one destination node and one or multiple relay nodes. From the perspective of one relay node, the upstream nodes means the source node and/or other relay nodes from which the current relay node receives signal, along the transmission direction of the relay path. While the downstream nodes means the destination node and/or other relay node to which the current node transmits signal, along the transmission direction of the relay path.

The relay station’s reception resource(s) are resources on which the relay station receives data. The relay station’s transmission resource are resources on which the relay station transmits data.

The relay station 420 is configured to receive Relay Scheduling Information (RSI), e.g. RSI 820 as described below with respect to Fig. 8 in more detail. The RSI 820 may comprise one or any combination of the following parameters: identities of the relay station 420 and other relay stations, e.g. relay station 430, within the relay path 400, each relay station’s 420, 430 transmission resource, in particular relaying slot format and/or frequency channel, each relay station’s 420, 430 transmission power, each relay station’s 420, 430 transmission beam, each relay station’s 420, 430 modulation and coding scheme.

The data frame 422 may be arranged according to a predetermined relay time slot format, e.g. relay time slot format 900 described below with respect to Fig. 9, comprising a relay control section 903, a relay payload section 901 and a blank section 902. The relay station 420 may be configured to shift the relay payload section 901 of a received data frame 422 by a specific number of symbols in time and to fill-up leading symbols before the relay payload section 901 with the relay control section 903 and ending symbols after the relay payload section 901 with the blank section 902. The relay payload section 901 of a data frame 422 may comprise transmission symbols for transmission of downlink (DL), uplink (UL) and/or sidelink (SL) signals. The blank section 902 may comprise blank symbols for accommodating symbol-level relaying time shift and Guard Period to compensate near-far effect. The relay control section 903 may comprises relay control signals carrying Relaying Notification Information (RNI) 810, preamble and/or reference signal.

Downlink, uplink and sidelink signals are general terms for these signals. They also include relayed versions of these signals, i.e. relayed DL, relayed UL and relayed SL signals.

The relay station 420 may be configured to receive an assignment to a particular relay time slot format, e.g. relay time slot format 900 depicted in Fig. 9, that is common to a group of relay stations, e.g. including relay stations 420, 430, in particular the group of relay stations 420, 430 along the relay path 400. The particular relay time slot format 900 may be indicated by a relay time SFGI.

In an implementation form, the relay payload section 901 for a relay station 420 transmitting on sidelink 1300 (as shown in Fig. 13) may be filled with sidelink symbols (S). In an implementation form, the relay payload section 901 for a relay station 420 transmitting on Uu link 1400 (as shown in Fig. 14) may comprise a section of downlink symbols (D) and a section of uplink symbols (U) which are separated by one or more blank symbols (X).

The relay station 420 may be configured to: determine the SICCI 610 (e.g. as shown in Fig. 6) and/or Channel Information (Cl) 620 (e.g. as shown in Fig. 6) of the relay path 400 and transmit the SICCI 610 and/or the Cl 620 to a central scheduler, in particular a base station 1 10 and/or exchange the SICCI 610 and/or Cl 620 between nodes (e.g. 410, 420, 430, 440) of the relay path 400.

The relay station 420 may be configured to receive Relay Scheduling Information (RSI), e.g. RSI 820 as described below with respect to Fig. 8, from a central scheduler, in particular a base station 1 10, and schedule data relaying 422, 423 and adjust resources based on the RSI 820.

The RSI 820 may be based on Quality of Service requirements, in particular delay and throughput requirements, of the relay path 400.

The relay station 420 may be configured to receive Relaying Notification Information (RNI), e.g. RNI 810 as described below with respect to Fig. 8, from other relay nodes, e.g. node 430. The RNI 810 may notify voluntary relay nodes 430 which are configured to assist the relay station 420 in data relaying 422, 423, e.g. as described below with respect to Figures 10 to 12.

The relay station 420 may comprise a processor, configured to process the received data frame 422 based on one of the following schemes: Amplify & Forward, Amplify, Construct & Forward, Equalize & Forward, Equalize-Precode & Forward, Decode & Forward.

Scheduling of the relay station 420 and other relay stations, e.g. relay station 430, may be performed by a central scheduler. Such a central scheduler, e.g. implemented by a base station 1 10, can be used for scheduling at least one relay station 420, 430, in particular a relay node or a UE with relay function, for relaying data 422, 423 along the relay path 400 in the wireless network. As described above, the relay station 420, 430 is configured to receive a data frame 422 in one or more frequency sub-channels within a time slot 402 and forward the data frame 423 in the same or neighboring frequency sub-channels within the same time slot 402.

The central scheduler is configured to receive Self-Interference Cancellation Capability Information (SICCI), e.g. SICCI 610 as described below with respect to Fig. 6 in more detail, from the at least one relay station 420, 430. The SICCI 610 indicates a level of selfinterference across the frequency sub-channels for the at least one relay station 420 and a number of other relay stations 430 within the relay path 400, and schedule data relaying 422, 423 of the at least one relay station 420, 430 based on the SICCI 610.

The central scheduler may be further configured to schedule data relaying of the at least one relay station based on Channel Information, Cl, wherein the Cl indicates a quality of a channel between any pair of relay stations or between relay stations and base station for each frequency sub-channel.

As described above with respect to the relay station 420, the SICCI 610 may comprises one or any combination of the following parameters: a ratio of transmit signal to receive leakage power 61 1 for at least one sub-channel, a node index 612 for uniquely identifying the relay station within the relay path, a frequency sub-channel index 613a, 613b for uniquely identifying a frequency sub-channel used by the relay station (Tx subchannel index 613a is used to identify Tx subchannel, while Rx subchannel index 613b is used to identify Rx subchannel), and a beam pair of transmit beam index 614 and receive beam index 615 for which beam pair the ratio of transmit signal to receive leakage power 61 1 applies, e.g. as described below with respect to Fig. 6.

The central scheduler may be configured to schedule data relaying 422, 423 of the at least one relay station 420, 430 based on Relay Scheduling Information (RSI), e.g. RSI 820 as described below with respect to Fig. 8. The RSI 820 may comprise at least one of the following: identities of the relay station 420 and other relay stations 430 within the relay path 400, each relay station’s 420, 430 transmission resource, in particular relaying slot format and/or frequency channel, each relay station’s 420, 430 transmission power, each relay station’s 420, 430 transmission beam, each relay station’s 420, 430 modulation and coding scheme. In the following, an exemplary implementation of a relay station is described. Relay node 420 receives the L1 frame, e.g. data 422 from upstream nodes, e.g. source node 410 while transmitting simultaneously to downstream nodes, e.g. relay node 430 within the same time slot 402. The behavior of a relay station supporting low-latency relaying based on Full- Duplex according to the disclosure, e.g. relay node 420 or 430 can be described by the following relations:

> u _m \ IDs of users along the relaying path; source: m=0

> The index set of transmitting frequency channels (e.g. RBs) of user u _m at

> The index of transmitting time slot of user u _m : s _{U n}

> Co-channel FD relay:

> Adjacent-channel FD relay: s _{U n} = s _Um-1 and c _{U n} n c _{U n-i} = 0

> Non-FD relay: s _{U n} > s _Um-1

The relay station processes the received data which results in a small increase of relay processing delay (e.g. by equalizing and forwarding). While for conventional mesh relay, delay time is given by the relation:

for the disclosed full duplex relay, the delay time is given by the relation:

That means, delay for full duplex relay is much smaller than delay for conventional mesh relay. T delay ^ delay

Table 1 illustrates latency for various relay processing types, such as EF and AF relay processing. In particular, for EF relay processing, latency is on symbol level while for AF relay processing, latency is on sample level.

Table 1 : Latency for various relay processing types (S: source, D: destination, R: relay)

For maintaining OFDM orthogonality, T _proc should be less than the CP (cyclic prefix) length for amplify or construct & forward. T _proc should be an integer multiple (> 1 ) of OFDM symbol length for all other cases as shown in Table 2.

Table 2: Time shift options for relay processing

As described above, the concept described in this disclosure can be implemented by a relay node or by a UE with relay function. Such a new type UE with Full-Duplex Relay Function may be based on a traditional Repeater relying on RF isolation between TX & RX antennas, however at poor performance of AF and further performance degradation due to non-ideal RF isolation. The new type UE may have a dedicated relay node and path. By implementing Full-Duplex Relay Function according to the disclosure, latency can be significantly reduced and reliability can be accordingly increased.

Alternatively, such new type UE with Full-Duplex Relay Function may be based on LTE-A Relay implementing decode and forward which may result in large delay of at least two subframes. For Inband, the new type UE may rely on RF isolation between TX & RX antennas. The new type UE may include a dedicated relay node and path. Different LTE relay classes may be provided dependent on duplex format as exemplarily shown in Table 3.

Table 3: Parameters of new type UE with Full-Duplex Relay Function based on LTE-A

Relay By implementing Full-Duplex Relay Function according to the disclosure, latency can be significantly reduced and reliability can be accordingly increased.

Fig. 5a shows a schematic diagram of exemplary time-frequency resources 500a that may be applied for a conventional Mesh/Relay. It can be seen that relaying is separated in time. A first resource 501 , e.g. of source node 410 as depicted in Fig. 4 is separated in time from a second resource 502, e.g. of first Relay 420 depicted in Fig. 4 and also separated in time from a third resource 503, e.g. of second Relay 430 depicted in Fig. 4. This relaying separated in time results in a large delay 504 for the conventional Mesh/Relay shown in Fig. 5a.

Fig. 5b shows a schematic diagram of exemplary time-frequency resources 500b that may be applied for Full-Duplex Enabled Relaying according to the disclosure. It can be seen that relaying may overlap in time and frequency thanks to full-duplex. Hence, delay 505 can be greatly reduced.

The first resource 501 , e.g. of source node 410 as depicted in Fig. 4 is overlapping in time and frequency with the second resource 502, e.g. of first Relay 420 depicted in Fig. 4. The first resource 501 and the second resource 502 further overlap in time with the third resource 503, e.g. of second Relay 430 depicted in Fig. 4. This time and/or frequency overlapped relaying results in a short delay 505 for the disclosed Full-Duplex Enabled Relaying according to the disclosure as shown in Fig. 5b.

Fig. 6 shows a schematic diagram 600 illustrating Self-Interference Cancellation Capability Information (SICCI) 610 and Channel Information (Cl) 620 according to the disclosure.

In the upper diagram, SICCI 610 is illustrated as information per Tx subchannel 601 and Rx subchannel 602 for an exemplary node m, where Tx subchannels 601 are defined from 1 to K and Rx subchannels 602 are defined from 1 to K. The node m is an example of a relay node in the relay path (e.g. of relay stations 420, 430 shown in Fig. 4) as well as source node (e.g. source node 410 shown in Fig. 4 or base station 1 10 shown in Fig. 1 ) and destination node (e.g. destination node 440 shown in Fig. 4 or any of UEs 140, 150 shown in Fig. 1 ). Tx Subchannels 601 describe the Tx frequency-time resources (or resource blocks) of node m while Rx Subchannels 602 describe the Rx frequency-time resources (or resource blocks) of node m. SICCI 610 includes the following parameters:

• Ratio 61 1 of Tx signal to Rx leakage power ratio: {r™}

• Node index 612: m = 1 ,2, ..., N

• Tx Sub-channel index 613a: k = 1 ,2, ..., K

• Rx Sub-channel index 613b: I = 1 ,2, ..., K

• Optional: beam indices

• Tx beam index 614: b _ΐc

• Rx beam index 615: b _Bc

SICCI includes the ratio(s) of the transmitted signal power to the received leakage power for at least a pair of transmitting and receiving frequency sub-channels. Optionally, it may be extended to consider different Tx/Rx beam pairs (indexed with b _Tc and b _Kc ). Each node has its specific SICCI, which should be reported to scheduler/BS or shared among the nodes. Depending on the implementation, the SICCI can be either measured during device production and stored permanently or lively calibrated during device’s booting phase or running time.

In the lower diagram, channel information (Cl) 620 is illustrated as information between two nodes. As described above, nodes 601 describe the relay nodes in the relay path (e.g. relay stations 420, 430 shown in Fig. 4) as well as source node (e.g. source node 410 shown in Fig. 4 or base station 1 10 shown in Fig. 1 ) and destination node (e.g. destination node 440 shown in Fig. 4 or any of UEs 140, 150 shown in Fig. 1 ). Cl 620 includes the channel information between different nodes m and n (e.g. between BS and UE) at each sub-band: {H™}, where m, n = 1 ,2, N.

Beside SICCI 610, Channel information 620 can be optionally processed for performing relay processing.

Fig. 7 shows a schematic diagram 700 illustrating Self-Interference Cancellation Capability Information (SICCI) 610 according to the disclosure in more detail. As described above with respect to Fig. 6, SICCI 610 is illustrated as information per Tx subchannel 601 and Rx subchannel 602 for an exemplary node m. In Fig. 7, an exemplary number of four Tx subchannels and an exemplary number of four Rx subchannels are illustrated.

In Fig. 7, an exemplary configuration for the SICCI 610 is shown where the ratio 61 1 of Tx signal to Rx leakage power ratio is about -30dB for k=0 corresponding to co-channel selfinterference 701 , about -50dB for k=1 corresponding to adjacent-channel self-interference 702 and about -70dB for k=2 corresponding to adjacent-channel self-interference 703.

An optional extension to consider beam pairs is shown in Fig. 7. For k=0, the Tx beam index 614: _tx and Rx beam index 615: b _Bc form a first matrix 71 1 including characteristic values of the respective Tx and Rx beams. For k=1 , the Tx beam index 614: b _ΐc and Rx beam index 615: b _Bc form a second matrix 712 including characteristic values of the respective Tx and Rx beams. For k=2, the Tx beam index 614: b _ΐc and Rx beam index 615: b _Bc form a third matrix 713 including characteristic values of the respective Tx and Rx beams.

Fig. 8 shows a schematic diagram illustrating Relaying Notification Information (RNI) 810 and Relay Scheduling Information (RSI) 820 according to the disclosure in a detailed representation.

The RNI 810 may be sent by a relay node to notify other nodes its upcoming relaying action while processing the received signal from upstream.

The RNI 810 includes the following parameters:

The relay node’s upstream resource (freq. channel & time slot)

The relay node’s upstream nodes

The relay node’s downstream nodes

The relay node’s transmission resource for relay signal

FD relaying slot format (OFDM symbol carry the same TB shift within the same slot) Frequency channel

Beam index

(Optional) The relay node’s modulation and coding scheme, spatial transmission scheme.

The RSI 820 may be sent by a central scheduler to specify a node’s relay action and also notify other nodes.

The RSI 820 includes scheduled resources for the retransmissions by relay, i.e.:

Identities of source, relay and destination nodes

Each node’s transmission resource

FD relaying slot format (OFDM symbol carry the same TB shift within the same slot)

Frequency channel

Each node’s transmission power

Each node’s transmission beam

(Optional) Each node’s modulation and coding scheme, spatial transmission scheme

Fig. 9 shows a schematic diagram of the new relaying frame format 900 according to the disclosure. The relaying frame format 900 is defined over a time slot 904 for a source node, e.g. source node 410 of Fig. 4, for Relay 1 , e.g. first relay node 420 of Fig. 4 and for Relay 2, e.g. second relay node 430 of Fig. 4.

Source node 410 includes a payload section 901 of DL, UL or SL symbols followed by one or more blank sections 902. First relay node 420 includes a relay control section 903 followed by the payload section 901 of DL, UL or SL symbols followed by one or more blank sections 902. Second relay node 430 includes one or more relay control sections 903 followed by the payload section 901 of DL, UL or SL symbols followed by one or more blank sections 902 (not shown here).

Frame format 900 for DL/UL/SL enables the co-channel/adjacent-channel full duplex relaying as described above with respect to Figures 4 to 8. In relay frame format, the DL/UL/SL transmission 901 is shifted by K OFDM symbols in time. The leading symbols before relay transmission are used to transmit relay control signal 903 carrying RNI, preamble, RS, etc. Blank OFDM symbols 902 follow the transmission symbols 901 for accommodating symbol-level relaying time shift and Guard Period (GP) to compensate near-far effect.

Fig. 10 shows an exemplary message sequence chart 1000 illustrating scheduled relaying nodes and resource selection according to the disclosure.

A scheduler 1020 (e.g. a base station 1 10 as shown in Fig. 1 ) decides on the relaying path and the resource usage of source node 410, relay nodes 420, 430 and destination node 440. The scheduler may serve as a central entity, collecting QoS requirement, SICCI and Cl from all nodes for assisting the scheduling decision.

The scheduler 1020 can select gainful sub-channels for retransmissions among nodes, avoid self-interference from relay Tx to upstream Rx, decide on relaying path and resource allocation to fulfill QoS requirements and provide incremental Cl report from nodes to reduce signaling overhead. One node can simultaneously relay multiple upstream transmissions.

An application interface 1010 is used to provide E2E QoS information (such as delay and throughput requirement) to the scheduler 1020.

The scheduled relaying nodes and resource selection includes the following functionalities: The scheduler 1020 collects 1001 SICCI from the source node 410, the relay nodes 420, 430 and the destination node 440. Source node 410, relay nodes 420, 430 and destination node 440 may initiate 1002 mutual measurement of Cl to measure channel information between source node 410, the relay nodes 420, 430 and the destination node 440. E2E QoS, e.g. delay and throughput requirement is provided 1003 by the application interface 1010 to the scheduler 1020. The scheduler 1020 collects 1004 the Cl from source node 410, relay nodes 420, 430 and destination node 440. Based on SICCI and optionally Cl, the scheduler 1020 makes scheduling decision 1005 and schedules 1006 relaying nodes 420, 430 and resources with RSI. When scheduled, source node 410, relay nodes 420, 430 and destination node 440 may implement E2E relaying communication 1007.

Fig. 1 1 shows an exemplary message sequence chart 1 100 illustrating voluntary relaying nodes and resource selection according to the disclosure. Any relay station 420, 430 described above with respect to Figures 4 and 1 1 can serve as a voluntary relaying node. Any node voluntarily decides to relay the transmission from other nodes. The selection of resources (freq. channel & time slot) is based on the mutually measured and exchanged Cl and SICCI; and the mutual sensing of available resources. Since the scheduler’s coordination is missing, the relaying parameters should be notified in RNI.

In FD relaying, RNI is transmitted during relay processing (Equalize/Amplify/Decode) right before the relay transmission.

One node can simultaneously relay multiple upstream transmissions.

The voluntary relaying nodes and resource selection includes the following functionalities: Source node 410, relay nodes 420, 430 and destination node 440 may initiate 1 101 mutual measurement of Cl to measure channel information between source node 410, the relay nodes 420, 430 and the destination node 440 and sensing of available resources. E2E QoS, e.g. delay and throughput requirement is provided 1 102 by the application interface 1010 to the source node 410. Cl and SICCI can be mutually exchanged 1 103 between source node 410, relay nodes 420, 430 and destination node 440. Notification of voluntary relay parameters in RNI can be mutually exchanged 1 104 between source node 410, relay nodes 420, 430 and destination node 440. Then, source node 410, relay nodes 420, 430 and destination node 440 may implement E2E relaying communication 1 105.

Fig. 12 shows an exemplary message sequence chart 1200 illustrating hybrid (scheduled and voluntary) relaying nodes and resource selection according to the disclosure.

In this scenario, the scheduled relay is also assisted by voluntary nodes. A voluntary node can strengthen the transmission of others if free resources are still available. One node can simultaneously relay multiple upstream transmissions. Multiple upstream transmissions can be processed by a relay node and then be combined and forwarded to downstream nodes.

The following functionality can be implemented: The scheduler 1020 collects 1201 SICCI from the source node 410, the relay nodes 420, 430 and the destination node 440. E2E QoS, e.g. delay and throughput requirement is provided 1202 by the application interface 1010 to the scheduler 1020. Source node 410, relay nodes 420, 430 and destination node 440 may initiate 1203 mutual measurement of Cl to measure channel information between source node 410, the relay nodes 420, 430 and the destination node 440. The scheduler 1020 collects 1204 the Cl from source node 410, relay nodes 420, 430 and destination node 440. The scheduler 1020 broadcasts 1205 the SICCI and Cl to source node 410, relay nodes 420, 430 and destination node 440. Mutual distribution 1206 of Cl and SICCI is performed between source node 410, relay nodes 420, 430 and destination node 440. Based on SICCI and optionally Cl, the scheduler 1020 makes scheduling decision 1207 and schedules 1208 relaying nodes 420, 430 and resources with RSI, e.g. RSI 820 as described above with respect to Fig. 8. Notification 1209 of voluntary relay parameters is sent from relay nodes 420, 430 to destination node 440. Finally, source node 410, relay nodes 420, 430 and destination node 440 may implement E2E relaying communication 1210.

Fig. 13 shows a schematic diagram illustrating an exemplary 5G NR Low-Latency Full- Duplex Relaying slot format 1300 for the Sidelink according to the disclosure.

5G NR Low-Latency Full-Duplex Relaying slot format - sidelink 1300 is defined for source node 410, relay nodes 420, 430 and destination node 440 as shown above with respect to Fig. 4. One slot including 14 OFDM symbols 1301 are depicted. The source node 410 includes sidelink symbols“S” as symbols number 1 to 11 , while symbols number 12 to 14 are blank symbols“X”. For first relay node 420, the symbols of source node 410 are delayed by 1 symbol, where leading symbol is filled with RNI and the last two symbols are blank symbols“X”. For second relay node 430, the symbols of first relay node 420 are delayed by 1 symbol, where two leading symbol are filled with RNI and the last symbol is blank symbol “X”. For destination node 440, the same arrangement of symbols from the second relay node 430 arrive. In source node 410 all symbols are Tx symbols 1310. In first relay node 420, the first 1 1 sidelink symbols“S” are transmitted in full duplex (FD) mode 1320 while the last 3 symbols“S” and“X”,“X” are Tx symbols 1310. In second relay node 430, the first 12 symbols“S(RNI)”,“S(RNI)”,“S” are transmitted in full duplex (FD) mode 1320 while the last 2 symbols“S” and“X” are Tx symbols 1310. In destination node 440, the first 13 symbols“S” are Rx symbols and the last“X” symbol is a Tx symbol. Sidelink symbol“S” may thus include RNI, e.g. RNI 810 as described above with respect to Fig. 8.

FD-relaying SFGI can be carried in RNI. FD relay transmissions are the following: Option 1 : frequency-shifted in order to avoid interference at the destination node (flexible FDD); Option 2: co-frequency channel (Full Duplex). Blank symbols may be used for transmission of feedback information or additional control information like next slot format, new relay status information etc. Source node 410, relay nodes 420, 430 and destination node 440 are all assigned to a particular slot format. The joint set of these slot formats can be specified as a type of FD- relaying SFGI that is assigned to the group.

Fig. 14 shows a schematic diagram illustrating an exemplary 5G NR Low-Latency Full- Duplex Relaying slot format 1400 for the Uu link according to the disclosure.

5G NR Low-Latency Full-Duplex Relaying slot format - Uu link 1400 is defined for source node 410, relay nodes 420, 430 and destination node 440 as shown above with respect to Fig. 4. One slot including 14 OFDM symbols is depicted. The source node 410 includes an exemplary number of four downlink symbols“D”, followed by an exemplary number of three blank symbols“X” followed by an exemplary number of six uplink symbols“U” followed by one blank symbol“X”. For first relay node 420, the downlink symbols of source node 410 are delayed by 1 symbol (to the right) and the uplink symbols of source node 410 are delayed by 1 symbol (to the left), the leftmost symbol is filled up with D(RMI) symbol and the rightmost symbol is filled up with blank symbol“X”. This results for the first relay node 420 in the following frame format:“D(RNI)” as first symbol,“D” as second to fifth symbol, “X” as sixth to seventh symbol,“U(RNI)” as eight to ninth symbols,“U” as tenth to thirteenth symbols and“X” as fourteenth symbol. Upstream symbol“U” and downstream symbol“D” may thus include RNI, e.g. RNI 810 as described above with respect to Fig. 8.

For second relay node 430, the downlink symbols of first relay node 420 are delayed by 1 symbol (to the right) and the uplink symbols of first relay node 420 are delayed by 1 symbol (to the left), the leftmost symbol is filled up with D(RMI) symbol and the rightmost symbol is filled up with blank symbol“X”. This results for the second relay node 430 in the following frame format: “D(RNI)” as first to second symbols,“D” as third to sixth symbol,“X” as seventh symbol,“U(RNI)” as eighth symbol,“U” as ninth to twelfth symbols and“X” as thirteenth to fourteenth symbols.

For destination node 440, the downlink symbols of second relay node 430 remain unshifted and the uplink symbols of second relay node 430 are delayed by 1 symbol (to the left), the rightmost symbol is filled up with blank symbol“X”. This results for the destination node 440 in the following frame format:“D” as first to sixth symbols,“X” as seventh symbol,“U” as eighth to eleventh symbols and“X” as twelfth to fourteenth symbols.

In source node 410 symbols“D” and“X” are Tx symbols 1310 and symbols“U” are Rx symbols 1330. In first relay node 420, symbols “D(RNI)”, “D”, “U(RNI)” and “U” are transmitted in full duplex (FD) mode 1320 while symbols“X” are Tx symbols 1310. In second relay node 430, symbols“D(RNI)”,“D”,“U(RNI)” and“U” are transmitted in full duplex (FD) mode 1320 while symbols“X” are Tx symbols 1310. In destination node 440 symbols“D” are Rx symbols 1330 while symbols“X” and“U” are Tx symbols 1310.

Source node 410, relay nodes 420, 430 and destination node 440 are all assigned to a particular slot format. The joint set of these slot formats can be specified as a type of FD- relaying SFGI that is assigned to the group.

An FD-relaying SFGI may be assigned for the group of source node 410, destination node 440 and relays 420, 430. BS and UE are not assumed to have FD capability. Hence, the slot formats for BS and UE belong to the set of agreed slot formats in 5G NR. However, the slot formats of BS and UE must be aligned with the FD relays to get the benefits of low latency and high reliable relay communication. The selected Group FD-relaying SFI ensures that nodes in the group have appropriately configured slots.

Fig. 15 shows a schematic diagram illustrating the current r14 LTE-V2X sidelink frame structure 1501 and an enhancement 1502 with relaying with equalize (precode) and forward according to the disclosure.

In the current r14 LTE-V2X sidelink frame structure 1501 , DMRS (demodulation reference signals) may be included in symbols 3, 6, 9 and 12 while guard period (GP) symbol may be included in symbol 14 of a frame.

In the enhancement frame structure 1502 with relaying with equalize (precode) and forward, the source node 410 may have the following frame structure: DMRS symbols at positions 1 , 4, 7, 10 and GP symbols at positions 13 and 14 of the frame. Arriving at the Relay, e.g. relay node 420 shown in Fig. 4 or relay node 430, the DMRS symbols and the GP symbols are shifted by 1 to the right and the top position is filled up with RNI symbol, e.g. RNI 810 as described above with respect to Fig. 8. The destination node 440 may have the same frame structure than the relay node 430.

In source node 410 all symbols are Tx symbols 1310. In relay node 420 the first twelve symbols are duplex mode symbols 1320 that may be transmitted in duplex mode while the last two symbols are Tx symbols 1310. In the destination node 440 the first thirteen symbols are Rx symbols 1330 and the last GP symbol is a Tx symbol 1310. In the enhancement frame structure 1502 depicted in Fig. 15, the relay transmission is shifted by 1 or more symbols. DMRS symbol is front-loaded allowing the relay node to perform channel estimation to perform equalization resulting in forwarding as early as possible for achieving low-latency.

Fig. 16 shows a schematic diagram illustrating a method 1600 for relaying data along a relay path in a wireless network according to the disclosure. The relay path may be a relay path 400 as described above with respect to Fig. 4 including a source node 410 one or more relay nodes 420, 430 and a destination node 440.

The method 1600 comprises receiving 1601 a data frame 422, by a relay station 420, in one or more frequency sub-channels within a time slot 402, e.g. as described above with respect to Figures 4 to 15.

The method 1600 further comprises forwarding 1602 the data frame 423, by the relay station 420, in the same or neighboring frequency sub-channels within the same time slot 402 dependent on Self-Interference Information 610, SICCI, wherein the SICCI 610 indicates a level of self-interference across the frequency sub-channels for the relay station 420 as well as for a number of other relay stations 430 within the relay path 400, e.g. as described above with respect to Figures 4 to 15.

The present disclosure also supports a computer program product including computer executable code or computer executable instructions that, when executed, causes at least one computer to execute the performing and computing steps described herein, in particular the methods and procedures described above. Such a computer program product may include a readable non-transitory storage medium storing program code thereon for use by a computer. The program code may perform the processing and computing steps described herein, in particular the methods and procedures described above.

While a particular feature or aspect of the disclosure may have been disclosed with respect to only one of several implementations, such feature or aspect may be combined with one or more other features or aspects of the other implementations as may be desired and advantageous for any given or particular application. Furthermore, to the extent that the terms "include", "have", "with", or other variants thereof are used in either the detailed description or the claims, such terms are intended to be inclusive in a manner similar to the term "comprise". Also, the terms "exemplary", "for example" and "e.g." are merely meant as an example, rather than the best or optimal. The terms“coupled” and“connected”, along with derivatives may have been used. It should be understood that these terms may have been used to indicate that two elements cooperate or interact with each other regardless whether they are in direct physical or electrical contact, or they are not in direct contact with each other.

Although specific aspects have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific aspects shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific aspects discussed herein.

Although the elements in the following claims are recited in a particular sequence with corresponding labeling, unless the claim recitations otherwise imply a particular sequence for implementing some or all of those elements, those elements are not necessarily intended to be limited to being implemented in that particular sequence.

Many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the above teachings. Of course, those skilled in the art readily recognize that there are numerous applications of the invention beyond those described herein. While the present invention has been described with reference to one or more particular embodiments, those skilled in the art recognize that many changes may be made thereto without departing from the scope of the present invention. It is therefore to be understood that within the scope of the appended claims and their equivalents, the invention may be practiced otherwise than as specifically described herein.