WO2022161608A1

WO2022161608A1 - Dynamic selection of transmission scheme

Info

Publication number: WO2022161608A1
Application number: PCT/EP2021/051923
Authority: WO
Inventors: Dawid Koziol; Kalle Petteri Kela; Hans Thomas HÖHNE; Ping-Heng Kuo; Nhat-Quang NHAN
Original assignee: Nokia Technologies Oy
Priority date: 2021-01-28
Filing date: 2021-01-28
Publication date: 2022-08-04

Abstract

A method comprising: evaluating a burst characteristic relating to an arrival time of at least one data packet belonging to a data flow; determining one of two or more transmission schemes based on the evaluated burst characteristic; and transmitting the at least one data packet belonging to the data flow based on the determined transmission scheme.

Description

Dynamic selection of transmission scheme

Technical Field

The present disclosure relates to selection of transmission scheme, in particular to dynamic selection of transmission scheme based on burst characteristics.

Abbreviations

3GPP 3^rd Generation Partnership Project

3G / 4G / 5G 3^rd 14^th 15^th Generation

5QI 5G QoS Indicator

BAT Burst Arrival Time

BSD Bucket Size Duration

CN Core Network

DL Downlink

DRB Data Radio Bearer eNB evolved NodeB gNB next generation NodeB

HARQ Hybrid Automatic Repeat reQuest

HOT Industrial Internet of Things

LCH Logical Channel

LCP Logical Channel Prioritization

MAC Medium Access Control

MAC CE MAC Control Element

MDBV Maximum Data Burst Volume

NACK Negative Acknowledgment

PBR Prioritized Bit Rate

PDB Packet Delay Budget

PDCP Packet Data Convergence Protocol

PDU Protocol Data Unit

PHY Physical Layer

PUSCH Physical Uplink Shared Channel

QoS Quality of Service

RAN Radio Access Network

Rel Release

RLC Radio Link Control RRC Radio Resource Control

Rx Receive, reception

SCS Subcarrier Spacing

TB Transmission Block

TSC Time Sensitive Communications

TSCAI TSC Assistance Information

TSN Time Sensitive Networks

Tx Transmit, transmission

UE User Equipment

UL Uplink

Background

Network coding takes advantage of coding gain from combining at least two consecutive packets in a data flow and transmitting the packet comprising the coded version of the two or more packets. At the side of the receiving device, the coded packet can be used to retrieve original packets which were unsuccessfully received, or which were not sent at all (some coding techniques allow to retrieve original packets using only coded packets). In order to retrieve the original packets, the receiving device is not required to successfully receive all the packets (either original or coded ones), as the decoding operation can be successful when only a subset of the transmitted packets is received. Thanks to this, network coding is believed to provide a transmission reliability comparable to that of packet duplication, but with higher radio resources utilization efficiency or a higher transmission reliability with the same resource utilization. Some of the more popular coding techniques applicable in network coding are, e.g. XOR coding or Reed-Solomon coding.

Furthermore, in 3GPP Rel-16, as part of the work on 5G system enhancements for Industrial Internet of Things (HOT) use cases, especially for Time Sensitive Networks (also denoted as Time Sensitive Communications), Time Sensitive Communications Assistance Information (TSCAI) was specified. TSCAI comprises parameters describing the characteristics of a certain TSC data flow such as:

• Burst Arrival Time (Rel-16) denoting the absolute time of burst arrival;

• Burst Periodicity (Rel-16) denoting time intervals with which bursts arrive at the transmitter;

• Flow Direction (Rel-16) - either DL or UL. Those parameters are provided from the Core Network to RAN/gNB together with data flow QoS parameters characterized by 5QI, such as Maximum Data Burst Volume (MDBV) and Packet Delay Budget (PDB). Altogether, they are used by the gNB to optimize the scheduling, e.g. adjust occurrences of Configured Grants or Semi-Persistent Scheduling assignments to the time of data arrival and adjust their size to the expected data volume.

In 3GPP Rel-17, enhancements to TSCAI are being discussed as part of FSJIOT study item. The following additional parameters are being proposed to be added to TSCAI:

• Burst Spread denoting uncertainty of the burst arrival time;

• Survival Time specifying the time for which the application remains operational after not receiving an expected message/burst.

In PCT/EP2020/053088, inter-arrival time of packets has been proposed as a criterion for the transmitter to determine whether conventional PDCP duplication or network coding should be applied.

Brief Summary

It is an object of the present disclosure to improve the prior art.

According to a first aspect of the disclosure, there is provided a method comprising: evaluating a burst characteristic relating to an arrival time of at least one data packet belonging to a data flow; determining one of two or more transmission schemes based on the evaluated burst characteristic; and transmitting the at least one data packet belonging to the data flow based on the determined transmission scheme.

The method may be a method for transmission scheme selection.

According to a second aspect of the disclosure, there is provided apparatus comprising: one or more processors, and memory storing instructions that, when executed by the one or more processors, cause the apparatus to perform the method according to the first aspect. According to a third aspect of the disclosure, there is provided a computer program product comprising a set of instructions which, when executed on an apparatus, is configured to cause the apparatus to carry out the method according to the first aspect. The computer program product may be embodied as a computer-readable medium or directly loadable into a computer.

The following items are additionally provided:

Item 1.1. Apparatus comprising: one or more processors, and memory storing instructions that, when executed by the one or more processors, cause the apparatus to: determine one of plural burst descriptors for a burst of data units to be transmitted based on a characteristic of the burst and an assistance parameter; identify one of plural transmission schemes such that the identified transmission scheme is associated to the determined burst descriptor according to a stored association associating each of the burst descriptors to a respective one of the transmission schemes; transmit the data units of the burst according to the identified transmission scheme.

Item 1.2. The apparatus according to item 1.1 , wherein the burst belongs to a data flow, and each of the burst descriptors, the assistance parameter, the transmission schemes, and the association belongs to the data flow.

Item 1.3. The apparatus according to any of items 1 .1 and 1.2, wherein the burst descriptor comprises at least one of a data volume in the burst, a number of the data units in the burst, an arrival time of the burst, a size of the data units in the burst, and a spread of the burst.

Item 1.4. The apparatus according to any of items 1.1 to 1.3, wherein at least one of: at least one of the transmission schemes comprises a duplication of one of the data units; and at least another one of the transmission schemes comprises a network coding of a plurality of the data units.

Item 1.5. The apparatus according to any of items 1 .1 to 1 .4, wherein the instructions, when executed by the one or more processors, further cause the apparatus to: buffer the data units in a buffer for a time not longer than a data units buffering time before the data units are transmitted; wherein the assistance parameter comprises the data units buffering time; the burst descriptor is determined based on a number of the data units in the buffer at a time when at least one of the following events occurs:

• when the data units buffering time lapses after a first data unit of the data units was buffered in the buffer;

• if the burst is characterized by a burst spread received from a sender of the burst: when the burst spread ends;

• if the assistance parameter comprises a maximum number of the data units in the buffer: when the buffer comprises the maximum number of the data units; and

• when the burst comprises a burst marker according to which the burst ends.

Item 1 .6. The apparatus according to item 1 .5, wherein the instructions, when executed by the one or more processors, further cause the apparatus to: decide whether one of the data units has to be transmitted urgently; inhibit the buffering of the one of the data units if the one of the data units has to be transmitted urgently; transmit the one of the data units according to a predefined transmission scheme.

Item 1.7. The apparatus according to any of items 1 .5 to 1 .6, wherein the instructions, when executed by the one or more processors, further cause the apparatus to: inform a receiving device of the transmission on the number of the data units based on which the burst descriptor is determined.

Item 1.8. The apparatus according to any of items 1 .5 to 1 .7, wherein the instructions, when executed by the one or more processors, further cause the apparatus to: reset the data units buffering time periodically with a time period; wherein the time period is determined based on characteristics of the burst received from a sender of the burst.

Item 1.9. The apparatus according to any of items 1 .1 to 1 .4, wherein the instructions, when executed by the one or more processors, further cause the apparatus to: determine an arrival time of the burst, wherein all the data units of the burst are arrived at the arrival time; the assistance parameter is an arrival time threshold, and the arrival time of the burst is the characteristic of the burst.

Item 1.10. The apparatus according to item 1.9, wherein the instructions, when executed by the one or more processors, further cause the apparatus to: compare the arrival time of the burst with the arrival time threshold; wherein if the arrival time of the burst is earlier than the arrival time threshold: the one of the plural burst descriptors is determined such that the associated transmission scheme comprises one of a duplication of one of the data units and a network coding of a plurality of the data units; and if the arrival time of the burst is not earlier than the arrival time threshold: the one of the plural burst descriptors is determined such that the associated transmission scheme does not comprise any of the duplication of one of the data units and the network coding of a plurality of the data units.

Item 1.11. The apparatus according to item 1.10, wherein the instructions, when executed by the one or more processors, further cause the apparatus to: divide an arriving burst into a first burst and a second burst, wherein all the data units of the first burst arrive earlier than the arrival time threshold, and all the data units of the second burst do not arrive earlier than the arrival time threshold; determine the one of the plural burst descriptors for the first burst such that the associated transmission scheme comprises one of a duplication of one of the data units of the first burst and a network coding of a plurality of the data units of the first burst; determine the one of the plural burst descriptors for the second burst such that the associated transmission scheme does not comprise any of the duplication of one of the data units of the second burst and a network coding of the plurality of the data units of the second burst.

Item 1.12. The apparatus according to any of items 1.9 to 1.11 , wherein the instructions, when executed by the one or more processors, further cause the apparatus to: setting the arrival time threshold based on a transmission time length and a transmission scheme for the transmission of the burst.

Item 1.13. The apparatus according to any of items 1.9 to 1.12, wherein the transmission schemes comprise logical channel prioritizations. Item 2.1. Apparatus comprising: one or more processors, and memory storing instructions that, when executed by the one or more processors, cause the apparatus to: determine one of plural burst descriptors for a burst of data units received from a transmitter; identify one of plural transmission schemes such that the identified transmission scheme is associated to the determined burst descriptor according to a stored association associating each of the burst descriptors to a respective one of the transmission schemes; decode the data units of the received burst based on the identified transmission scheme.

Item 2.2. The apparatus according to item 2.1 , wherein the burst belongs to a data flow, and each of the burst descriptors, the transmission schemes, and the association belongs to the data flow.

Item 2.3. The apparatus according to any of items 2.1 to 2.2, wherein at least one of: at least one of the transmission schemes comprises a duplication of one of the data units; and at least another one of the transmission schemes comprises a network coding of a plurality of the data units.

Item 2.4. The apparatus according to any of items 2.1 to 2.3, wherein the burst descriptor comprises at least one of a data volume in the burst, a number of the data units in the burst, an arrival time of the burst, a size of the data units in the burst, a spread of the burst, a number of the data units in a buffer of the transmitter.

Item 2.5. The apparatus according to item 2.4, wherein the instructions, when executed by the one or more processors, further cause the apparatus to: monitor if an indication of the number of the data units in the buffer of the transmitter is received; wherein the burst descriptor comprises the number of the data units in the buffer of the transmitter.

Item 2.6. The apparatus according to any of items 2.4 and 2.5, wherein the instructions, when executed by the one or more processors, further cause the apparatus to: count a number of the received data units originally transmitted before the burst of the data units is received; set the number of the data units in the buffer of the transmitter equal to the number of the received data units originally transmitted before the burst of the data units is received; wherein the burst descriptor comprises the number of the data units in the buffer of the transmitter.

Item 3.1. The apparatus according to any of items 1.1 to 2.6, wherein each of the data units is a respective data packet or a respective protocol data unit or a respective service data unit.

According to some embodiments of the present disclosure, at least one of the following advantages may be achieved:

• efficient usage of radio resources;

• packet/burst latency target is not jeopardized;

• transmission reliability is improved.

It is to be understood that any of the above modifications can be applied singly or in combination to the respective aspects to which they refer, unless they are explicitly stated as excluding alternatives.

Brief description of the drawings

Further details, features, objects, and advantages are apparent from the following detailed description of the preferred embodiments of the present disclosure which is to be taken in conjunction with the appended drawings, wherein:

Fig. 1 shows a graphical representation of various TSCAI parameters;

Fig. 2 shows a message flow according to some example embodiments of the present disclosure;

Fig. 3 presents a message flow according to an example embodiment of the present disclosure;

Fig. 4 shows examples of how transmission duration can be estimated according to some example embodiments of the present disclosure; Fig. 5 presents exemplary considerations when choosing the transmission scheme depending on the actual time of burst arrival according to some example embodiments of the present disclosure;

Fig. 6 shows RLC subset selection based on PDU arrival time according to some example embodiments of the present disclosure;

Fig. 7 shows an exemplary processing procedure at the UE side according to some example embodiments of the present disclosure;

Fig. 8 shows an apparatus according to an example embodiment of the present disclosure; Fig. 9 shows a method according to an example embodiment of the present disclosure;

Fig. 10 shows an apparatus according to an example embodiment of the present disclosure; Fig. 11 shows a method according to an example embodiment of the present disclosure;

Fig. 12 shows an apparatus according to an example embodiment of the present disclosure; Fig. 13 shows a method according to an example embodiment of the present disclosure; and

Fig. 14 shows an apparatus according to an example embodiment of the present disclosure.

Detailed description of certain embodiments

Herein below, certain embodiments of the present disclosure are described in detail with reference to the accompanying drawings, wherein the features of the embodiments can be freely combined with each other unless otherwise described. However, it is to be expressly understood that the description of certain embodiments is given by way of example only, and that it is by no way intended to be understood as limiting the disclosure to the disclosed details.

Moreover, it is to be understood that the apparatus is configured to perform the corresponding method, although in some cases only the apparatus or only the method are described.

A graphical representation of various TSCAI parameters is shown in Fig. 1. As shown in Fig. 1 , TSC burst may comprise one or more packets. In general, a burst comprises one or more packets which the UE/gNB may handle as one or plural PDlls. The number of packets in a burst is not known in advance (only the volume of data can be estimated based on MDBV). It is worth noting that the burst duration is assumed to be very low (in the level of tens or hundreds of microseconds). Example transmission schemes are:

• transmission without duplication;

• transmission with packet duplication;

• transmission with network coded packets (with different sub-schemes: e.g. XOR coding or Reed-Solomon -based coding);

• transmission with or without repetitions.

Instead of the term “transmission scheme”, terms like “transmission configuration”, “transmission setting”, “TX configuration”, “transmission mode” etc. may be used synonymously.

The choice of the best transmission scheme for the burst is unpredictable due to the following reasons:

• The number of packets in a burst of packets is unknown in advance to the transmitter (be it TSC burst or a number of packets within a non-TSC data flow)

• The exact burst arrival time may differ due to burst arrival spread, which impacts the time left for the transmission to meet the end application’s expected time of arrival of burst. Hence, different bursts may have different reliability requirements for initial transmission attempt as the remaining time to deliver the burst varies.

• The channel state will influence the transmission duration over the air interface.

• Applying packet duplication blindly decreases the resource efficiency significantly.

• On the other hand, applying network coding may further delay the packet delivery due to having to wait for subsequent packets in a flow to create packet combinations (coded packets). At the same time, the higher number of coded packets increases coding efficiency and is desired in case delay requirements are not compromised.

As mentioned above, network coding techniques and/or PDCP duplication and/or PHY layer techniques can be applied to a traffic flow to increase its reliability. However, they all have some issues, e.g. resource inefficiency of PDCP duplication, and additional delay imposed by network coding techniques.

Furthermore, as described earlier, bursty traffics are expected in TSC (and other deployments) where each burst may comprise one or multiple packets (or a burst could be handled as one PDCP PDU), and the number of packets in each burst could be different. Considering only inter-arrival time between two packets for selecting a network coding scheme might sometimes be not very efficient. In some cases, it may be more efficient to choose whether to apply a network coding scheme and which network coding scheme to apply based on additional factors.

Some example embodiments of this present disclosure propose selection of the transmission scheme based on additional factors.

Some example embodiments of the present disclosure provide a method allowing the transmitter to dynamically choose the most resource efficient transmission scheme, which at the same time meets the reliability and/or latency target of the traffic, per each burst of packets based on the instantaneous burst characteristics.

1 . For a certain data flow (e.g. represented by a data radio bearer (DRB)) comprising one or more bursts of data, the transmitter may be configured with the following: o Burst descriptor defining the burst characteristics such as: data volume in a burst and/or number of packets in a burst and/or arrival time of a burst, packet sizes in the burst etc. o A respective transmission scheme is associated with a corresponding burst descriptor configured in the transmitter. For example, a single respective transmission scheme is associated to each of the burst descriptors. One transmission scheme may be associated to one burst descriptor or to plural burst descriptors. o One or more Assistance parameters allowing the transmitter to determine dynamically one of the burst descriptors applicable to a burst (a certain group of packets).

2. After the configuration, the transmitter may use the assistance parameter(s) to match the current burst of packets to one of the configured burst descriptors.

3. Based on the burst descriptor, the transmitter may choose its corresponding (associated) transmission scheme and transmit the burst according to this transmission scheme.

Fig. 2 shows a message flow according to some example embodiments of the present disclosure. In the example of Fig. 2, the UE (transmitting device) transmits packets (a burst) arrived for transmission (e.g. from upper layers such as an application layer).

At step S201.: First, the UE (i.e., the transmitting device, or in detail, the processor and memory thereof) is configured by the network (e.g., gNB) by one or more configurations comprising one or more burst descriptors, associated one or more transmission schemes, and one or more assistance parameters.

At step S202.: The application sends a burst of packets to the transmitter of the UE.

At step S203.: Based on the assistance parameter(s), the processor of the UE determines which of the burst descriptors matches the received burst of packets.

At step S204.: The UE processor selects the transmission scheme based on the determined burst descriptor.

At step S205.: The UE transmitter transmits the burst of packets according to the selected transmission scheme.

Hereinafter, some example embodiments will be described in greater detail:

Example embodiment 1 - dynamic transmission scheme selection based on the number of buffered packets

In this example embodiment, the processor of the transmitting device (e.g., the processor of a UE in uplink, or the processor of a gNB in downlink) dynamically selects the most resource efficient transmission scheme, which at the same time meets the reliability target of the traffic. The selection is made depending on the number of packets in a burst. The method comprises the following steps:

At step S301 : The transmitting device (i.e. the processor and memory thereof) is configured with the following assistance parameter(s) for a configured data flow/data radio bearer. The assistance parameter(s) allow the processor of the transmitting device to determine the burst size.

The assistance parameter(s) includes a packet buffering timer (Tbuffering) indicating the maximum time for which the transmitter waits for packets to arrive before transmitting them. During this time, the packets are buffered in the buffer of the transmitter. The assistance parameter(s) may further include a packet number parameter (NMax_burst) indicating the maximum number of packets in the buffer for which the transmitter waits before transmitting them.

At step S301 , the processor and memory of the transmitting device is additionally configured with a respective transmission scheme for each of the potential burst sizes (i.e. the number of packets in a burst, Ncurrent_burst). In this case, each of the burst descriptors may indicate different burst sizes and the corresponding one of the transmission schemes may be applied. For example, a. Ncurrent_burst =1 apply transmission scheme #1 b.

_ apply transmission scheme #2 c. ... d. N_Current_burst = N_Max_burst apply transmission scheme #X

At step S301 , optionally the transmitter may be also configured to send original packets without any delay (while still storing them in the buffer to be able to send later coded versions of them).

After the initial configuration of the assistance parameter(s), burst descriptors, and transmission schemes for a data flow (e.g. for a certain data radio bearer), the transmitter receives a packet #1 of a burst of packets from the application at step S302.

When the transmitter receives the packet #1 , the processor of the transmitting device resets and then starts the buffering timer Tbuffering, and waits for the packets to arrive to the buffer while the buffering timer is working, at step S303. Depending on configuration, Tbuffering may be started e.g. at the earliest time when a packet is expected to arrive for transmission (i.e. in the beginning of burst spread window or burst arrival time defined by TSCAI), or when the first packet actually arrives at the transmitter.

After starting the buffering timer, the transmitter receives packets #2, #3, #4 from the Application at step S304a and stores the packets at the buffer. The transmitter transmits the (original) packets #1 to #4 to the receiving device at step S304b.

After the buffering timer expired, at step S305, the processor of the transmitting device may determine the size of the burst. In some embodiments, the burst size may be determined at the time when:

1) Tbuffering expires;

2) burst spread ends (if transmitter side is configured with burst arrival time, periodicity of the bursts, and burst spread);

3) The number of buffered packets reaches NMax_burst (if configured); or

4) if the burst packets comprises a burst marker that indicates the end of the burst, and the end of the burst has been reached.

The burst size is determined based on the number of packets buffered for the processed data flow. The steps S303 and S305 may be performed at PDCP layer (or, PDCP entity) of the transmitting device.

Once the burst size is known, the processor of the transmitting device may determine (or, select) the transmission scheme based on the determined burst size, at step S306. The transmitter sends all the buffered packets using the determined transmission scheme, at step 307. For example, if the transmission scheme indicates a network coding, the transmitter codes the burst of packets and transmits them to the receiving device. If the transmission scheme indicates a PDCP duplication, the transmitter duplicates the burst of packets and transmits them to the receiving device.

After transmitting the buffered packets, the processor of the transmitting device sets Ncurrent_burst to 0 and flushes the buffer, at step 308.

When the next packet (e.g., packet #5) arrives at the transmitter, the processor of the transmitting device restarts the buffering timer Tbuffering, at step S310. And then, the transmitting device repeats the procedure S304 to S308 in order to transmit the packet #5 (and potentially subsequent packets) at step S311.

The transmitting device may repeat the procedure explained at Fig. 3 as long as the data flow is established and as long as it is configured to do so.

Hereinafter, the transmission schemes used at S307 are explained more in detail. An example of the implementation of this embodiment is a 5G network where the gNB configures the UE to perform either PDCP packet duplication or network coding of packets as the transmission schemes. In this case, the transmitter of the UE is the transmitter of Fig. 3 and the receiver of the gNB is the receiver of Fig. 3. For example,

• In case there is a single buffered packet (Ncurrent_burst =1), the UE uses PDCP duplication with a configured number of copies (for example, to send between 2 and 4 copies, but this is not limiting the embodiment)

• If the number of buffered packets is larger than 1 , then the UE applies network coding instead. The applied network coding method depends on the number of packets that are available for coding, i.e. on the current value of Ncurrent_burst, e.g.: o If Ncurrent_burst =2, the corresponding transmission scheme foresees sending one coded packet comprising Packet 1 (P1) and Packet 2 (P2) (typically in addition to sending the original packets)

O If Ncurrent_burst ⁼3, depending on configuration, the corresponding transmission scheme foresees either:

sending one coded packet comprising P1 , P2 and P3 (typically in addition to sending the original packets); or

sending two coded packets: (P1 , P2) and (P2, P3) (typically in addition to sending the original packets); or

-> sending three coded packets: (P1 , P2), (P2, P3) and (P1 , P3) (typically in addition to sending the original packets), etc. O If If Ncurrent_burst ^— 4, depending on configuration, the corresponding transmission scheme foresees either:

sending two coded packet comprising P1 , P2 and P3, P4 (typically in addition to sending the original packets); or

-> sending three coded packets: (P1 , P2) and (P2, P3) and (P3, P4) (typically in addition to sending the original packets), or

sending any combination of 2, 3, or 4 packets (typically in addition to sending the original packets) o And so on

Typically, the UE should be configured with as many transmission schemes as NMax_burst.

In addition to the coded packets, the transmitter may typically send the original packets.

According to some example embodiments of the present disclosure, the receiving side (in this example: the receiver of the gNB) is aware of the transmission scheme (TX configuration) that was used due to one of the following measures:

• Transmission schemes (i.e. TX configurations) per number of packets in UL are configured in the processor of the UE by the gNB (e.g. using RRC signaling). If the transmitter of the gNB is the transmitter of Fig. 3, gNB may inform (configure) the UE (receiving device) on the transmission scheme per number of packets used in DL.

• The transmitting device may inform the receiving device about the number of packets buffered for a certain group of coded packets, e.g. using MAC CE signaling for a TB carrying coded packets or within PDCP header; or

• If the transmitter transmits the original packets prior to the coded packets, the receiving device may determine the number of packets in the transmitter’s buffer based on the number of original packets transmissions that were received before (either successfully or not successfully).

The receiving device may distinguish the original packets from the coded packets e.g. from the packet header which may include that information (e.g. include sequence numbers of coded packets). As another option, it may be preconfigured (e.g. standardized) that certain sequence numbers (SNs) are coded versions from certain other sequence numbers. Then basic modulo calculation may be used to determine if a packet is an original packet or a coded version of a certain original packets. It is recommended that the buffering timer is set in such a way that prevents exceeding PDB for each of the packets in a buffered burst. It could be set, e.g. PDB required for the packets in the QoS flow (based on 5QI) minus estimated transmission time for the buffered packets.

NMax_burst parameter is optional. It may be determined implicitly by the number of transmission schemes as configured in item 2 above. Yet another alternative is to omit NMax_burst parameter and in case more packets are buffered than transmission schemes are available, packets are split into groups, or the extra packets are sent with a default transmission scheme (e.g. are always duplicated).

For example, some example embodiments of the present disclosure are implemented in the PDCP layer. Although the UL direction is used as an example, the same technique is correspondingly applicable to DL.

Example Embodiment 2: Dynamic transmission scheme selection based on the number of packets in a TSC burst

This example embodiment is applicable to periodic flows (e.g. periodic TSC flows) for which gNB received information on expected burst arrival time and burst spread, e.g. as part of TSCAI information. gNB may receive this information from the CN or from another gNB during UE handover. gNB may provide UE with this information, too.

Example embodiment 2 is similar to Example embodiment 1 with the following differences (here explained for the example of a TSC flow and TSCAI information):

• The buffering timer is set and handled in a different way which is dependent on the TSCAI parameters of the TSC flow, e.g. o Timer is started for the first time at the time of expected burst_arrival_time minus (burst_spread/2) and is restarted periodically according to the burst periodicity o Timer duration can be set, e.g. to PDB minus burst_spread minus esti m ated_T x_ti m e o The buffering timer value for each burst/packet may additionally depend on whether there is a risk of survival time violation. For example, if transmission of the previous burst has failed, then the transmitter may process the upcoming packet immediately without waiting for the timer expiration (i.e. timer value =0), to allow for more time within the PDB for potential retransmissions in the lower layer and to minimize probability of consecutive failure.

• If the burst is assumed to be very short in duration and to be received within burst spread window or shortly after the burst spread window, then the configuration of the timer parameter can also be omitted. UE still chooses the transmission scheme based on the number of packets in a single burst.

Example embodiment 3: Dynamic transmission scheme selection based on actual burst arrival time

In this example embodiment, the network may first estimate burst transmission time length for different transmission schemes and other relevant transmission parameters, such as SCS and MCS, e.g. o Tx with different repetitions number o Tx with different subcarrier spacings (SCS) o Tx with duplication with different number of copies (also denoted as legs) o Tx with different modulation and coding schemes (MCS).

In this case, the transmission schemes additionally comprise the other relevant transmission parameters to be applied in other protocol layers such as MAC and PHY.

Examples of how transmission duration can be estimated is presented in Fig. 4. Fig. 4 shows two examples of a subframe of 1 ms duration, each divided into 14 mini-slots. The packet delay budget (PDB) may be equal to 1 ms, too. The burst arrives at the beginning of the subframe.

In the upper subframe, two mini-slots are needed for scheduling and processing delay before a transmission takes places in the third mini-slot. Thereafter, 5 mini-slots are kept free for potential receipt of NACK according to HARQ. If NACK is received, another two mini-slots are required for scheduling and processing prior to retransmission of the previous transmission within the subframe. The delay budget includes the delay in the receiver due to Rx processing (UE Rx processing delay). As can be seen in the upper part of Fig. 4, in this case, a retransmission is possible within the subframe such that the UE receives the packet within the delay budget.

In the lower subframe of Fig. 4, scheduling and processing delay for the first transmission starts later because the burst is spread, e.g. due to jitter. Therefore, the transmission takes place in the 7^th mini-slot. 5 mini-slots after the transmission, the transmitter receives NACK from HARQ. However, in this case, there is not sufficient time left in the subframe (delay budget) for another scheduling and processing delay, a retransmission, and a RX processing delay.

Based on estimated transmission time lengths for different transmission schemes, the network configures mapping between the burst arrival time and the transmission scheme (the transmission scheme may additionally comprise some of the other relevant transmission parameters) in the UE/gNB:

• If burst arrives late (e.g. after nominal burst arrival time or after BAT + burst spread I 4 etc.), there is no time for coding or repetitions or retransmissions left in the subframe. Hence, the transmitter (e.g. the transmitter of the UE or the transmitter of the gNB) sends duplicate packets on various RLC channels and/or sends packets with high(er) SCS;

• If burst arrives early (e.g. before nominal burst arrival time, or before BAT + burst spread /4 etc.), there is time available for coding or repetitions. Hence, e.g. the transmitter of UE of the transmitter of gNB sends packets with a certain number of repetitions and retransmissions (if needed) or applies network coding for the packets within a burst.

Fig. 5 presents exemplary considerations when choosing the transmission scheme depending on the actual time of burst arrival. Fig. 5 shows another subframe, similar to Fig. 4. The burst arrives at the beginning of the subframe. The delay budget may be 1 ms. The burst is to be transmitted by 4 transmissions Tx #1 to Tx #4. For Tx #1 and Tx #2, there is sufficient time for retransmission in the subframe (delay budget). However, in Fig. 5, Tx #3 and Tx #4 are transmitted later than Tx #1 and Tx #2 so, there is not sufficient time in the subframe (delay budget) for retransmission (including RX processing delay).

In this case, the transmitter may split the arriving burst into two bursts (sub-bursts). The first sub-burst comprises all the packets arriving earlier than the arrival time threshold, and the second sub-burst comprises all the packets not arriving earlier than the arrival time threshold. These sub-bursts may be treated according to their respective characteristics, i.e. duplication and/or network coding may be applied for the first sub-burst, but not for the second sub-burst. As an alternative, the transmitter may treat the burst according to the latest transmission (which depends on the respective arrival time). In the example of Fig. 5, this is Tx#4. Since this transmission is too late for re-transmission, the whole burst is treated as being arrived late. I.e., duplication and/or network coding is not applied to the whole burst.

After the configuration and when data of the flow starts to arrive at the transmitter (e.g. the transmitter of the UE or the transmitter of the gNB), the processor of the transmitting device chooses the transmission scheme (potentially comprising modulation and coding scheme and/or SCS etc.) depending on the actual time of burst arrival per each incoming burst. For uplink, the different transmission schemes may correspond to different LCP settings in a MAC layer. A LCP setting may include the following:

• A set of LCP parameters, such as LCH priority, Prioritized Bit Rate (PBR), and Bucket Size Duration (BSD), and/or

• A set of LCH mapping restriction rules, indicating the uplink grant characteristics that should be satisfied to convey data from this LCH. The rules may include maximum subcarrier spacing, maximum PUSCH duration, allowed serving cells, allowed L1 priority, allowed configured grant configurations etc.

Therefore, a different LCP setting is used to process a data burst, depending on the arrival time of the data burst.

Fig. 6 shows an illustration of how Example embodiment 3 may be realized in UL. It is assumed that the PDCP of a DRB is configured with multiple RLC entities, and these RLC entities are divided into different subsets. The LCHs associated to the first RLC subset are configured with different LCP setting (e.g. LCH mapping restrictions) than the LCHs associated to the second RLC subset. Then, depending on the arrival time of a PDCP PDU of the burst, the PDCP determines which RLC subset it should submit the PDCP PDU to. For instance, for PDCP PDUs of the burst arrive earlier than a time point (arrival time threshold), the UE may have more delay budget so it can submit the PDCP PDUs to RLCs with LCH mapping restrictions that can tolerate more latency. Conversely, for PDCP PDUs of the burst arrive later than the time point (arrival time threshold), the UE does not have much time left to process the data, so it can submit the PDCP PDUs to RLCs with LCH mapping restrictions that enables low-delay transmission.

The delay of a transmission may be for instance influenced by the subcarrier spacing that is associated with a LCH mapping. A larger subcarrier spacing is associated with shorter symbol time, and hence depending on other system settings such as slot length it may be possible to transmit data with less latency in a logical channel that has larger subcarrier spacing.

In some aspect of the embodiment, the PDCP layer (or PDCH entity) of the transmitting device may select the RLC subset 1 when the arrival time of the burst of the packets is later than the offset threshold of the burst arrival time. In this case, the RCL subset 1 includes RLC entity 1 and RLC entity 2 which are corresponding to LCH 1 and LCH 2, respectively. The PDCP layer of the transmitting device may select the RLC subset 2 when the arrival time of the burst of the packets is earlier than the offset threshold. In this case, the RLC subset 2 includes the RLC 3 and RLC 4 which are corresponding to LCH 3 and LCH 4, respectively. That is, the PDCP layer of the transmitting device may select the RLC subset based on the actual packet arrival time and the offset threshold. And then, the processor of the transmitting device selects RLC based on LPC settings and transmits the burst on the selected RLC entity and LCH. If the PDCP selects the RLC 1 and/or RLC 2 of the RLC subset 1 , the transmitting device is able to transmit the burst by using large subcarrier spacing based on the LCH mapping restriction. If the PDCP selects the RLC 3 and/or RLC 4 of the RLC subset 2, the transmitting device is able to transmit the burst by using small subcarrier spacing based on the LCH mapping restriction.

Another way than choosing a different RLC may influence the likelihood for a transmission to meet the delay target are other MAC entity settings such as the maximal number of HARQ retransmissions that are possible, or the priority that an associated logical channel is configured with.

In some example implementations of example embodiment 3, the processor and memory of the UE (transmitting device) is first configured (via RRC, by the gNB) with an arrival time threshold (i.e. a threshold time offset comparing to the expected burst arrival time). The parameter allows the processor of the UE to determine which RLC subset it should select to process a PDCP PDU, depending on whether the burst arrives before or after this threshold. An exemplary processing procedure at the UE side is depicted in Fig. 7.

As shown in Fig. 7, in S710, the processor and memory of the UE receives a configuration from gNB. The configuration comprises two or more RLC subsets for a DRB. For each of the RLC subsets, the configuration comprises a respective LCP setting. In addition, the configuration comprises an offset threshold for the burst arrival time. In S720, if a burst (here: a PDCP PDU) arrives at the transmitter of the UE, the arrival time of the burst is determined. For example, the arrival time of the burst within a subframe is determined.

In S730, it is checked if the burst arrival time is before or after the offset threshold. If the burst arrives before the offset threshold (YES in S730), the method proceeds to S740. In S740, the transmitter of the UE submits the PDCP PDU of the burst to the first RLC subset with the first LCP setting. If the burst arrives after the offset threshold (NO in S730), the method proceeds to S750. In S750, the transmitter of the UE submits the PDCP PDU of the burst to the second RLC subset with the second LCP setting.

The receiver of the gNB may process the received burst according to the third example embodiment as usual.

An advantage of some example embodiments of the present disclosure is that the transmission scheme is selected in such a way that the packet/burst latency target is not jeopardized while radio resources efficiency is maximized. That is, network coding improves transmission reliability with resource efficiency superior to blind repetitions and/or PDCP duplication.

Fig. 8 shows an apparatus according to an example. The apparatus may be a transmitting device such as a terminal (e.g. UE) or a base station (e.g. gNB, eNB), a transmitter thereof, or an element of the transmitter. Fig. 9 shows a method according to an example. The apparatus according to Fig. 8 may perform the method of Fig. 9 but is not limited to this method. The method of Fig. 9 may be performed by the apparatus of Fig. 8 but is not limited to being performed by this apparatus.

The apparatus comprises means for determining 10, means for identifying 20, and means for transmitting 30. The means for determining 10, means for identifying 20, and means for transmitting 30 may be a determining means, identifying means, and transmitting means, respectively. The means for determining 10, means for identifying 20, and means for transmitting 30 may be a determiner, identify, and transmitter, respectively. The means for determining 10, means for identifying 20, and means for transmitting 30 may be a determining processor, identifying processor, and transmitting processor, respectively. The means for determining 10 determine one of plural burst descriptors for a burst of data units to be transmitted (S10). The determining is made based on a characteristic of the burst and an assistance parameter.

The means for identifying 20 identifies one of plural transmit schemes such that the identified transmit scheme is associated to the determined burst descriptor (S20). The identified transmit scheme is associated to the determined burst descriptor according to a stored association associating each of the burst descriptors to a respective one of the transmit schemes. I.e., a respective single transmit scheme is associated to each of the burst descriptors.

The means for transmitting 30 transmits the data units of the burst according to the identified transmit scheme (S30).

Fig. 10 shows an apparatus according to an example. The apparatus may be a receiving device such as a terminal (e.g. UE) or a base station (e.g. gNB, eNB), a receiver thereof, or an element of the receiver. Fig. 11 shows a method according to an example. The apparatus according to Fig. 10 may perform the method of Fig. 11 but is not limited to this method. The method of Fig. 11 may be performed by the apparatus of Fig. 10 but is not limited to being performed by this apparatus.

The apparatus comprises means for determining 110, means for identifying 120, and means for decoding 130. The means for determining 110, means for identifying 120, and means for decoding 130 may be a determining means, identifying means, and decoding means, respectively. The means for determining 110, means for identifying 120, and means for decoding 130 may be a determiner, identify, and decoder, respectively. The means for determining 110, means for identifying 120, and means for decoding 130 may be a determining processor, identifying processor, and decoding processor, respectively.

The means for determining 110 determines one of plural burst descriptors for a burst of data units received from a transmitting device (S110).

The means for identifying 120 identifies one of plural transmit schemes such that the identified transmit scheme is associated to the determined burst descriptor (S120). The identified transmit scheme is associated to the determined burst descriptor according to a stored association associating each of the burst descriptors to a respective one of the transmit schemes. I.e., a respective single transmit scheme is associated to each of the burst descriptors.

The means for decoding 130 decodes the data units of the received burst based on the identified transmit scheme (S130).

Fig. 12 shows an apparatus according to an example embodiment of the present disclosure. The apparatus may be a transmitting device such as a terminal (e.g. UE) or a base station (e.g. gNB, eNB), a transmitter thereof, or an element of the transmitter. Fig. 13 shows a method according to an example embodiment of the present disclosure. The apparatus according to Fig. 12 may perform the method of Fig. 13 but is not limited to this method. The method of Fig. 13 may be performed by the apparatus of Fig. 12 but is not limited to being performed by this apparatus.

The apparatus comprises means for evaluating 210, means for determining 220, and means for transmitting 230. The means for evaluating 210, means for determining 220, and means for transmitting 230 may be a evaluating means, determining means, and transmitting means, respectively. The means for evaluating 210, means for determining 220, and means for transmitting 230 may be a evaluator, determiner, and transmitter, respectively. The means for evaluating 210, means for determining 220, and means for transmitting 230 may be a evaluating processor, determining processor, and transmitting processor, respectively.

The means for evaluating 210 evaluates a burst characteristic (S210). The burst characteristic relates to an arrival time of at least one data packet. The at least one data packet belongs to a data flow.

The means for determining 220 determines one of two or more transmission schemes based on the evaluated burst characteristic (S220). The two or more transmission schemes may be configured for the data flow.

The means for transmitting 230 transmits the at least one data packet belonging to the data flow based on the determined transmission scheme (S230).

Each of the two or more transmission schemes may be related to one of plural subsets of radio link control entities. The method may further comprise receiving a configuration including information defining the two or more transmission schemes. The burst characteristic may comprise at least one of:

• an arrival time of at least one data packet including the first data packet,

• an ending time of at least one data packet including the first data packet,

• an arrival time of a burst including the first data packet,

• an ending time of the burst including the first data packet, and

• a time span of the burst, wherein the time span is the duration between the starting time of the burst and the ending time of the burst.

• Whether another burst was deemed successfully delivered.

At least one of the transmission schemes may comprise a duplication of one the first data packet; and at least another one of the transmission schemes may comprise a network coding of the first data packet and another data packet of the flow.

Fig. 14 shows an apparatus according to an embodiment of the present disclosure. The apparatus comprises at least one processor 810, at least one memory 820 including computer program code, and the at least one processor 810, with the at least one memory 820 and the computer program code, being arranged to cause the apparatus to at least perform at least one of the methods according to Figs. 9, 11, and 13 and related description.

Some example embodiments are explained with respect to a 5G network. However, the present disclosure is not limited to 5G. It may be used in other networks, too, e.g. in previous or forthcoming generations of 3GPP networks such as 3G, 4G, 6G, 7G, etc. The present disclosure is not limited to 3GPP networks but may be used for transmissions in other networks or in device-to-device transmissions, too.

A packet is an example of a data unit. Depending on the level where an example embodiment of the present disclosure is deployed, instead of a packet, the method according to some example embodiments of the present disclosure may be applied to another data unit such as a protocol data unit or a service data unit, and the apparatus according to some example embodiments of the present disclosure may be accordingly adopted. One piece of information may be transmitted in one or plural messages from one entity to another entity. Each of these messages may comprise further (different) pieces of information.

Names of network elements, network functions, protocols, and methods are based on current standards. In other versions or other technologies, the names of these network elements and/or network functions and/or protocols and/or methods may be different, as long as they provide a corresponding functionality.

If not otherwise stated or otherwise made clear from the context, the statement that two entities are different means that they perform different functions. It does not necessarily mean that they are based on different hardware. That is, each of the entities described in the present description may be based on a different hardware, or some or all of the entities may be based on the same hardware. It does not necessarily mean that they are based on different software. That is, each of the entities described in the present description may be based on different software, or some or all of the entities may be based on the same software. Each of the entities described in the present description may be deployed in the cloud.

According to the above description, it should thus be apparent that example embodiments of the present disclosure provide, for example, a transmitting device, such as a terminal (e.g. UE) or a base station (e.g. eNB, gNB), or a component thereof, an apparatus embodying the same, a method for controlling and/or operating the same, and computer program(s) controlling and/or operating the same as well as mediums carrying such computer program(s) and forming computer program product(s). According to the above description, it should thus be apparent that example embodiments of the present disclosure provide, for example, a receiving device, such as a terminal (e.g. UE) or a base station (e.g. eNB, gNB), or a component thereof, an apparatus embodying the same, a method for controlling and/or operating the same, and computer program(s) controlling and/or operating the same as well as mediums carrying such computer program(s) and forming computer program product(s).

Implementations of any of the above described blocks, apparatuses, systems, techniques or methods include, as non-limiting examples, implementations as hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof. Each of the entities described in the present description may be embodied in the cloud.

It is to be understood that what is described above is what is presently considered the preferred embodiments of the present disclosure. However, it should be noted that the description of the preferred embodiments is given by way of example only and that various modifications may be made without departing from the scope of the disclosure as defined by the appended claims.

Claims

27 Claims:

1. A method comprising: evaluating a burst characteristic relating to an arrival time of at least one data packet belonging to a data flow; determining one of two or more transmission schemes based on the evaluated burst characteristic; and transmitting the at least one data packet belonging to the data flow based on the determined transmission scheme.

2. The method according to Claim 1 , wherein each of the two or more transmission schemes is related to one of plural subsets of radio link control entities.

3. The method according to any of Claims 1 and 2, wherein the burst characteristic comprises at least one of: an arrival time of at least one data packet including the at least one data packet belonging to the data flow, an ending time of at least one data packet including the at least one data packet belonging to the data flow, an arrival time of a burst including the at least one data packet, an ending time of the burst including the at least one data packet belonging to the data flow, or a time span of the burst, wherein the time span is the duration between the starting time of the burst and the ending time of the burst.

4. The method according to any of claims 1 to 3, further comprising receiving a configuration including information defining the two or more transmission schemes.

5. The method according to any of claims 1 to 4, wherein at least one of: at least one of the transmission schemes comprises a duplication of the at least one data packet belonging to the data flow; and at least another one of the transmission schemes comprises a network coding of the at least one data packet belonging to the data flow and another data packet belonging to the data flow.

6. The method according to any of claims 1 to 5, wherein the two or more transmission schemes are configured for the data flow.

7. Apparatus comprising: one or more processors, and memory storing instructions that, when executed by the one or more processors, cause the apparatus to perform evaluating a burst characteristic relating to an arrival time of at least one data packet belonging to a data flow; determining one of two or more transmission schemes based on the evaluated burst characteristic; and transmitting the at least one data packet belonging to the data flow based on the determined transmission scheme.

8. The apparatus according to Claim 7, wherein each of the two or more transmission schemes is related to one of plural subsets of radio link control entities.

9. The apparatus according to any of Claims 7 and 8, wherein the burst characteristic comprises at least one of: an arrival time of at least one data packet including the at least one data packet belonging to the data flow, an ending time of at least one data packet including the at least one data packet belonging to the data flow, an arrival time of a burst including the at least one data packet, an ending time of the burst including the at least one data packet belonging to the data flow, or a time span of the burst, wherein the time span is the duration between the starting time of the burst and the ending time of the burst.

10. The apparatus according to any of claims 7 to 9, wherein the instructions, when executed by the one or more processors further cause the apparatus to perform receiving a configuration including information defining the two or more transmission schemes.

11 . The apparatus according to any of claims 7 to 10, wherein at least one of: at least one of the transmission schemes comprises a duplication of the at least one data packet belonging to the data flow; and at least another one of the transmission schemes comprises a network coding of the at least one data packet belonging to the data flow and another data packet belonging to the data flow.

12. The apparatus according to any of claims 7 to 11 , wherein the two or more transmission schemes are configured for the data flow.

13. A computer program product comprising a set of instructions which, when executed on an apparatus, is configured to cause the apparatus to carry out evaluating a burst characteristic relating to an arrival time of at least one data packet belonging to a data flow; determining one of two or more transmission schemes based on the evaluated burst characteristic; and transmitting the at least one data packet belonging to the data flow based on the determined transmission scheme.

14. The computer program product according to Claim 13, wherein each of the two or more transmission schemes is related to one of plural subsets of radio link control entities.

15. The computer program product according to any of Claims 13 and 14, wherein the burst characteristic comprises at least one of: an arrival time of at least one data packet including the at least one data packet belonging to the data flow, an ending time of at least one data packet including the at least one data packet belonging to the data flow, an arrival time of a burst including the at least one data packet, an ending time of the burst including the at least one data packet belonging to the data flow, or a time span of the burst, wherein the time span is the duration between the starting time of the burst and the ending time of the burst.

16. The computer program product according to any of claims 13 to 15, wherein the set of instructions, when executed on the apparatus, is configured to cause the apparatus to carry out receiving a configuration including information defining the two or more transmission schemes.

17. The computer program product according to any of claims 13 to 16, wherein at least one of: at least one of the transmission schemes comprises a duplication of the at least one data packet belonging to the data flow; and at least another one of the transmission schemes comprises a network coding of the at least one data packet belonging to the data flow and another data packet belonging to the data flow.

18. The computer program product according to any of claims 13 to 17, wherein the two or more transmission schemes are configured for the data flow.

19. The computer program product according to any of claims 13 to 18, embodied as a computer-readable medium or directly loadable into a computer.