WO2020020642A1

WO2020020642A1 - Client device and network access node for uplink pre-emption indication ack

Info

Publication number: WO2020020642A1
Application number: PCT/EP2019/068572
Authority: WO
Inventors: Bengt Lindoff; Thorsten Schier; Wenquan HU; Gustaf Claeson; Yongxia Lyu
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2018-07-27
Filing date: 2019-07-10
Publication date: 2020-01-30

Abstract

The invention relates to a client device and a network access node for uplink pre-emption indication acknowledgment. The client device (100) receives a first uplink grant (502) indicating uplink transmission in first uplink time-frequency resources and thereafter monitors for an indication signal (504) associated with the first uplink grant (502). Upon detection of the indication signal (504) the client device (100) transmits an acknowledgement signal (506) associated with the indication signal (504) to the network access node (300). Thereby, a reliable uplink pre-emption indication design is provided. Also, optimized spectrum utilization can be achieved by multiplexing plural client devices with different services, such as URLLC and eMBB, in an efficient and reliable way. Furthermore, the invention also relates to corresponding methods and a computer program.

Description

CLIENT DEVICE AND NETWORK ACCESS NODE FOR UPLINK PRE-EMPTION INDICATION ACK

Technical Field

The invention relates to a client device and a network access node for uplink pre-emption indication acknowledgment. Furthermore, the invention also relates to corresponding methods and a computer program.

Definitions of Acronyms & Glossaries

AL Aggregation Level

CCE Control Channel Element

CORESET Control Resource Set

CRC Cyclic Redundancy Check

CSS Common Search Space

DCI Downlink Control Information

eNB E-UTRAN NodeB

gNB next generation NodeB

ID Identity

NR New Radio

PDCCH Physical Downlink Control Channel

PDSCH Physical Downlink Shared Channel

PER Packet Error Rate

PI Pre-emption Indicator

PRB Physical Resource Block

PUSCH Physical Uplink Shared Channel

RNTI Radio Network Temporary Identifier

UCI Uplink Control Information

UE User Equipment

UE-ID User Equipment Identity

UL Uplink

URLLC Ultra Reliable and Low Latency Communication

USS UE-Specific Search Space

Background

A critical requirement of 3GPP 5G is support for ultra-low latency services - where latency expresses the time required for transmitting a message through the network. The requirement, one way over the Radio Access Network (RAN), for Ultra Reliable and Low Latency Communication (URLLC) has been set to a latency of 1 ms combined with a packet error rate (PER) of 10e-5. URLLC traffic requires higher reliability and lower latency than enhanced Mobile Broadband (eMBB) traffic. Thus, when URLLC is multiplexed with eMBB traffic, the URLLC traffic needs to be treated differently from the eMBB traffic, otherwise, the reliability of URLLC traffic will be the same as the eMBB traffic. This affects all network layers, including the physical layer.

The stringent requirements of URLLC on latency and reliability allow only for a very scarce utilization of the available time and frequency resources. Once a User Equipment (UE) has time critical URLLC data to send, it is crucial that the transmission can be scheduled and sent out as soon as possible. With non-deterministic and sporadic URLLC traffic an actual transmission does not happen frequently, but when it occurs it must be sent out quickly and reliably. This need for an immediate transmission opportunity restricts the number of active URLLC UEs that can be served at the same time. As a consequence, a big portion of the available time and frequency resources cannot be utilized for URLLC, since it always must be guaranteed that there are resources for Physical Downlink Control Channel (PDCCH) and Physical Downlink Shared Channel (PDSCH) and/or Physical Uplink Shared Channel (PUSCH) transmission. For a better resource utilization, 3GPP has therefore studied how New Radio (NR) can support services with different requirements to be multiplexed on shared resources. The idea is that the services with relaxed demands, such as eMBB, can be scheduled on the same resources as potential URLLC transmissions but would be de-prioritized when an URLLC transmission actually is going to be performed.

In 3GPP Release 15 this issue has been addressed in the downlink (DL) with the introduction of DL pre-emption which means that a gNB is allowed to pre-empt an ongoing DL transmission (e.g. of eMBB type) to send other data with higher priority (e.g. of URLLC type) to either the same or to a different UE. After transmission with the higher priority data has been finished, the gNB can resume its earlier operation, i.e. its earlier lower priority transmission. When the eMBB transmission gets pre-empted, it is obvious that its decoding performance will be impacted. At least for the case of inter-UE multiplexing the eMBB UE does not even know that its transmission got pre-empted and that the gNB has replaced the data in some of its PRBs with data that is intended to someone else.

Summary

An objective of embodiments of the invention is to provide a solution which mitigates or solves the drawbacks and problems of conventional solutions. A further objective of the invention is to overcome problems of uplink pre-emption indication according to conventional solutions.

The above and further objectives are solved by the subject matter of the independent claims. Further advantageous embodiments of the invention can be found in the dependent claims.

According to a first aspect of the invention, the above mentioned and other objectives are achieved with a first client device for a wireless communication system, the first client device being configured to

receive a first uplink grant indicating uplink transmission in first uplink time-frequency resources;

monitor for an indication signal associated with the first uplink grant; and

transmit an acknowledgement signal associated with the indication signal upon detection of the indication signal.

The first uplink grant can be an uplink pre-emption indication.

An advantage of the first client device according to the first aspect is that a reliable uplink preemption indication design is provided. Also, optimized spectrum utilization can be achieved by multiplexing plural client devices with different service types, such as URLLC and eMBB, in an efficient and reliable way.

In an implementation form of a first client device according to the first aspect, the first client device being configured to, upon detection of the indication signal, perform at least one of discard uplink transmission in at least one part of the first time-frequency resources; abandon uplink transmission in at least one part of the first time-frequency resources; and

halt uplink transmission in at least one part of the first time-frequency resources.

Hence, the first client device has options of discard, abandon and halt uplink transmission available upon detection of the indication signal.

An advantage with this implementation form is that interference is avoided in the at least one part of the first time-frequency resources since said resources are freed up.

In an implementation form of a first client device according to the first aspect, monitor for the indication signal comprises at least one of monitor for the indication signal in a physical downlink control channel monitor for the indication signal in downlink control information;

monitor for the indication signal in a broadcast control channel; and

monitor for the indication signal in demodulation reference signals of a physical downlink control channel.

The broadcast control channel can also simply be denoted as a broadcast channel.

An advantage with this implementation form is that the client device knows where to monitor for the indication signal and by that the monitoring is made easier.

In an implementation form of a first client device according to the first aspect, cyclic redundancy check of the downlink control information is scrambled with at least one of

a common radio network temporary identifier,

a radio network temporary identifier associated with the first client device, and a radio network temporary identifier associated with a second client device.

An advantage with this implementation form is that the client device knows which scrambling sequence to use and thereby reducing the complexity in the decoding process.

In an implementation form of a first client device according to the first aspect, the first client device being configured to

transmit the acknowledgement signal in a physical uplink control channel.

An advantage with this implementation form is that the acknowledgement signal is transmitted in a well-defined channel thereby reducing the detection complexity at the network access node.

transmit the acknowledgement signal orthogonally coded with another signal in the physical uplink control channel.

An advantage with this implementation form is that uplink frequency resource utilization is improved due to the orthogonal coding. In an implementation form of a first client device according to the first aspect, the first client device being configured to

transmit the acknowledgement signal in a physical uplink shared channel.

An advantage with this implementation form is that the client device can send the acknowledgement signal simultaneously with other data transmission in the physical uplink shared channel and thereby uplink frequency resource utilization is improved.

puncture the physical uplink shared channel according to a pre-configuration pattern so as to make room for the acknowledgement signal.

An advantage with this implementation form is that the client device can send the acknowledgement signal simultaneously with other data transmission in the physical uplink shared channel and thereby uplink frequency resource utilization is improved due to puncturing of the physical uplink shared channel.

In an implementation form of a first client device according to the first aspect, the indication signal indicates an uplink transmission in second uplink time-frequency resources from a second client device, wherein the second uplink time-frequency resources at least partly overlap with the first uplink time-frequency resources.

An advantage with this implementation form is that interference is avoided in the second uplink time-frequency resources.

In an implementation form of a first client device according to the first aspect, the first client device is configured for a first type of service and the second client device is configured for a second type of service, and wherein the first type of service has lower priority than the second type of service.

An advantage with this implementation form is that the second type of service having higher priority is prioritized in the system.

In an implementation form of a first client device according to the first aspect, the first type of service is eMBB and the second type of service is URLLC. An advantage with this implementation form is that faster retransmission is possible for URLLC packets in case of eMBB and URLLC data collision making it easier to fulfil URLLC latency requirements.

According to a second aspect of the invention, the above mentioned and other objectives are achieved with a network access node for a wireless communication system, the network access node being configured to

allocate first uplink time-frequency resources for uplink transmission from a first client device;

receive a scheduling request from a second client device and obtain second uplink time- frequency resources for uplink transmission from the second client device;

determine an uplink time-frequency resource conflict based on the allocated first uplink time-frequency resources and the obtained second uplink time-frequency resources;

transmit an indication signal to the first client device, wherein the indication signal indicates that an uplink transmission from the second client device in the second uplink time- frequency resources at least partly overlaps with the first uplink time-frequency resources; monitor for an acknowledgement signal associated with the indication signal from the first client device.

An advantage of the network access node according to the second aspect is that a reliable uplink pre-emption indication design is provided. Also, optimized spectrum utilization can be achieved by multiplexing plural client devices with different service types, such as URLLC and eMBB, in an efficient and reliable way. Further, interference is avoided in the second uplink time-frequency resources.

In an implementation form of a network access node according to the second aspect, the network access node is further configured to

transmit a first uplink grant to the first client device, wherein the first uplink grant indicates uplink transmission in the first uplink time-frequency resources.

transmit a second uplink grant indicating the second uplink time-frequency resources to the second client device upon receiving the acknowledgement signal;

detect an uplink transmission from the second client device. Hence, according to this implementation form the network access node detects the uplink transmission from the second client device after having received the acknowledgement signal associated with the indication signal from the first client device. When the network access node has received the acknowledgement signal the network access node knows that uplink time- frequency resources can be freed up for the second client device.

An advantage with this implementation form is that the second client device can be allocated the second uplink time-frequency resources for uplink data transmission without interference.

transmit a further indication signal to the first client device upon not receiving the acknowledgement signal within a predetermined timeframe.

An advantage with this implementation form is that it will enable the first client device to receive the further indication signal and thereby free up the second uplink time-frequency resources for the second client device.

transmit a second uplink grant indicating the second uplink time-frequency resources to the second client device before receiving the acknowledgement signal;

detect an uplink transmission from the second client device upon receiving the acknowledgement signal.

obtain new second uplink time-frequency resources upon not receiving the acknowledgement signal within a predetermined timeframe;

transmit a new second uplink grant indicating the new second uplink time-frequency resources to the second client device. An advantage with this implementation form is that the second client device can be allocated new second uplink time-frequency resources for uplink data transmission without interference from the first client device.

According to a third aspect of the invention, the above mentioned and other objectives are achieved with a method for a first client device, the method comprises

receiving a first uplink grant indicating uplink transmission in first uplink time-frequency resources;

monitoring for an indication signal associated with the first uplink grant; and

transmitting an acknowledgement signal associated with the indication signal upon detection of the indication signal.

The method according to the third aspect can be extended into implementation forms corresponding to the implementation forms of the first client device according to the first aspect. Hence, an implementation form of the method comprises the feature(s) of the corresponding implementation form of the first client device.

The advantages of the methods according to the third aspect are the same as those for the corresponding implementation forms of the first client device according to the first aspect.

According to a fourth aspect of the invention, the above mentioned and other objectives are achieved with a method for a network access node, the method comprises

allocating first uplink time-frequency resources for uplink transmission from a first client device;

receiving a scheduling request from a second client device and obtain second uplink time-frequency resources for uplink transmission from the second client device;

determining an uplink time-frequency resource conflict based on the allocated first uplink time-frequency resources and the obtained second uplink time-frequency resources;

transmitting an indication signal to the first client device, wherein the indication signal indicates that an uplink transmission from the second client device in the second uplink time- frequency resources at least partly overlaps with the first uplink time-frequency resources; monitoring for an acknowledgement signal associated with the indication signal from the first client device.

The method according to the fourth aspect can be extended into implementation forms corresponding to the implementation forms of the network access node according to the second aspect. Hence, an implementation form of the method comprises the feature(s) of the corresponding implementation form of the network access node.

The advantages of the methods according to the fourth aspect are the same as those for the corresponding implementation forms of the network access node according to the second aspect.

The invention also relates to a computer program, characterized in program code, which when run by at least one processor causes said at least one processor to execute any method according to embodiments of the invention. Further, the invention also relates to a computer program product comprising a computer readable medium and said mentioned computer program, wherein said computer program is included in the computer readable medium, and comprises of one or more from the group: ROM (Read-Only Memory), PROM (Programmable ROM), EPROM (Erasable PROM), Flash memory, EEPROM (Electrically EPROM) and hard disk drive.

Further applications and advantages of the embodiments of the invention will be apparent from the following detailed description. Brief Description of the Drawings

The appended drawings are intended to clarify and explain different embodiments of the invention, in which:

- Fig. 1 shows a first client device according to an embodiment of the invention;

- Fig. 2 shows a method for a client device according to an embodiment of the invention;

- Fig. 3 shows a network access node according to an embodiment of the invention;

- Fig. 4 shows a method for a network access node according to an embodiment of the invention;

- Fig. 5 shows a wireless communication system according to an embodiment of the invention;

- Figs. 6a and 6b show a timing diagram for downlink and uplink pre-emption indication;

- Fig. 7 shows missed detection of uplink pre-emption indication resulting in an extra latency;- Figs. 8a and 8b illustrate some basic principles and advantages of embodiments of the invention;

- Fig. 9 shows a flow chart of an embodiment in a client device; and

- Fig. 10 shows a flow chart of an embodiment in a client device. Detailed Description

As previously stated in Release 15, downlink (DL) pre-emption indication (PI) has been introduced. The DL PI is sent after the pre-emption and shall help the UE when decoding the corrupted eMBB transmission. How the DL PI is used to facilitate the decoding is up to UE implementation and not further defined. The concept of DL pre-emption indication means that an ongoing transmission to UE1 gets pre-empted and a UE2 is served instead. After the reception of the transport block, UE1 gets informed by the DL PI that it has been pre-empted. This information may help the UE1 to enhance its decoding performance. It has also been discussed to introduce a similar mechanism for uplink (UL) pre-emption indication, which also has been called or labeled as UL cancellation indication, in Release 15 but 3GPP could not agree on the feasibility of such a mechanism for UL. In the following section the inventors present their analysis of UL pre-emption.

As opposed to the pre-emption indication in the downlink which is aimed to support the eMBB UE, the pre-emption indication in the UL is intended to enable URLLC transmission in the first place. In the downlink, it is easier since the gNB has full control and can stop transmitting to UE1 (e.g. using eMBB) and decide to serve UE2 (e.g. using URLLC) instead. The only performance hit is on the eMBB-UE, which is tolerable. The URLLC performance of UE2 is not impacted. In the uplink however it is much more complicated since the gNB must ensure that the URLLC transmission of UE2 can get scheduled quickly and also that its reception is not interfered by any other UE. Thus, in UL the UL PI must instruct the eMBB-UE to stop its transmission for some time so that the URLLC-UE2 can be received safely. That also means that in contrary to the DL PI which can come after the URLLC data has been sent, in UL, the pre-emption indication has to come before the URLLC data is going to be sent. In short the purpose and usage of pre-emption indication is in the downlink to help to protect the eMBB data performance and can be sent after the URLLC data has been sent. In the uplink purpose and usage of pre-emption indication is to help or enable URLLC data reception at the gNB, and must be sent before transmission of URLLC.

A timing diagram for both downlink and uplink pre-emption is illustrated in Figs. 6a and 6b. For the downlink case which is shown in 6a, the pre-emption indication can help the eMBB-UE 100 to improve its decoding performance and can be sent after the URLLC transmission from the URLLC-UE. A gNB allocates an eMBB data packet on PDSCH1 to UE1 eMBB. Then a PDSCH2 is sent to the UE2 URLLC in the middle of the eMBB data packet, which interferes with the eMBB data packet. After transmission of the eMBB data packet a DL PI is transmitted to the UE1 eMBB on a PDCCH. Then the UE1 eMBB knowns which part of the PDSCH1 that has been interfered and can adapt decoding according to this information.

For the uplink case which is shown in Fig. 6b, it is vital that the eMBB-UE 100 receives the UL PI, so that it switches off its transmission and the URLLC of the URLLC- UE 100^'can be reliably received. The UL PI must come before the URLLC transmission. A PUSCH for UL data packets has been allocated to UE1 eMBB. The gNB thereafter receives a SR from the UE2 URLLC and hence need an UL resource allocation for UE2 URLLC on the allocated eMBB UL resources. Then a UL PI is sent to the UE1 eMBB which stops its transmission during URLLC UE UL transmission.

In 3GPP several different schemes for UL pre-emption have been discussed in contributions from various companies. However, one aspect that has been left out from the discussions is how to ensure that the eMBB UE really has detected the UL PI so that it switches off its transmission. In the 3GPP discussions always an ideal UL PI has been assumed, i.e. the eMBB UE always detects the UL PI. All the discussion about possible schemes have been based on this assumption. But in real operation, this is not true and a weak spot of operation.

URLLC requires a very high reliability and a very short latency. In Release 15 the target BLER is 1 e-5. For Release 16 use cases have been identified that will require an even higher reliability (BLER of 1 e-6). The purpose of UL PI is to let URLLC and eMBB services share the same resources and to mute the eMBB when a URLLC transmission occurs. Considering the very high reliability requirement of URLLC, the eMBB UE would need to detect the UL PI every single time it has been transmitted, an ideal detection would be required. When the UL PI is missed, the eMBB UE will keep on transmitting which will very likely destroy the reception of the URLLC.

Even if the detailed scheme for the transmission of the UL PI has not been decided yet, it is very likely that UL PI will be conveyed in a downlink control information (DCI) which then is carried by a PDCCH. This can either be a UE specific DCI or a group-common DCI. Regardless which approach that will be selected, it needs to be detected very reliably. For eMBB, the PDCCH detection probability is usually in the range between 1 % down to 0.1 % (considering an overall eMBB BLER requirement of 10%). Thus, it will be very hard to guarantee an ideal reception of the UL PI. If the UL PI is missed by the eMBB UE, the decoding will very likely result in a failure which then means that the gNB has to schedule a re-transmission of the URLLC. This is illustrated in Fig. 7 which shows missed detection of UL PI resulting in an extra latency. Since the URLLC latency requirements are very strict in many use cases, one cannot afford to wait for the decoding result of the first transmission before scheduling a retransmission. Therefore, missing a pre-emption indication could lead to a violation of the URLLC requirements. More in detail, Fig. 7 shows UL PI transmitted by gNB is missed by UE1 (eMBB-PUSCH) and hence the UL transmission on PUSCH from UE2 (URLLC-PUSCH) is failed to be decoded in the gNB due to interference from UE1. A new UL PI is sent by gNB to UE1 and is successfully decoded by UE1 and URLLC UL transmission from UE2 is successfully decoded, at a price of additional latency introduced.

Hence, from the above analysis, the inventors propose a solution which solves and overcomes the above mentioned drawbacks and shortcomings of conventional UL PI approaches.

Embodiments of the invention introduce an UL Pre-emption Indication (PI) Acknowledge (ACK) signal from the UE. Hence, the invention proposes a solution where the eMBB UE, when the UL PI has been detected by the UE, transmits an ACK signal to the gNB, and then stops/discards its UL transmission. Proposals for PI ACK signal design covered by embodiments of the invention are also disclosed.

The gNB, once the ACK signal is detected, knows that eMBB UE(s) have detected the PI, and by that also know that the URLLC transmission will be non-interfered. However, if gNB does not receive an ACK, the gNB also knows that the URLLC transmission may be interfered, and can transmit a new UL grant fast or another UL PI to retrieve available UL resources for the URLLC UE, and thereby reduce the risk for violating the URLLC latency requirement.

Fig. 1 shows a first client device 100 according to an embodiment of the invention. In the embodiment shown in Fig. 1 , the first client device 100 comprises a processor 102, a transceiver 104 and a memory 106. The processor 102 is coupled to the transceiver 104 and the memory 106 by communication means 108 known in the art. The first client device 100 further comprises an antenna or antenna array 110 coupled to the transceiver 104, which means that the client device 100 is configured for wireless communications in a wireless communication system. That the first client device 100 is configured to perform certain actions can in this disclosure be understood to mean that the first client device 100 comprises suitable means, such as e.g. the processor 102 and the transceiver 104, configured to perform said actions.

According to embodiments of the invention the first client device 100 is configured to receive a first uplink grant 502 indicating uplink transmission in first uplink time-frequency resources. The first client device 100 is further configured to monitor for an indication signal 504 associated with the first uplink grant 502. The first client device 100 is further configured to transmit an acknowledgement signal 506 associated with the indication signal 504 upon detection of the indication signal 504. Fig. 2 shows a flow chart of a corresponding method 200 which may be executed in a first client device 100, such as the one shown in Fig. 1. The method 200 comprises receiving 202 a first uplink grant 502 indicating uplink transmission in first uplink time-frequency resources. The method 200 further comprises monitoring 204 for an indication signal 504 associated with the first uplink grant 502. The method 200 further comprises transmitting 206 an acknowledgement signal 506 associated with the indication signal 504 upon detection of the indication signal 504.

Fig. 3 shows a network access node 300 according to an embodiment of the invention. In the embodiment shown in Fig. 3, the network access node 300 comprises a processor 302, a transceiver 304 and a memory 306. The processor 302 is coupled to the transceiver 304 and the memory 306 by communication means 308 known in the art. The network access node 300 may be configured for both wireless and wired communications in wireless and wired communication systems, respectively. The wireless communication capability is provided with an antenna or antenna array 310 coupled to the transceiver 304, while the wired communication capability is provided with a wired communication interface 312 coupled to the transceiver 304. That the network access node 300 is configured to perform certain actions can in this disclosure be understood to mean that the network access node 300 comprises suitable means, such as e.g. the processor 302 and the transceiver 304, configured to perform said actions.

According to embodiments of the invention the network access node 300 is configured to allocate first uplink time-frequency resources for uplink transmission from a first client device 100. The network access node 300 is further configured to receive a scheduling request from a second client device 100^' and obtain second uplink time-frequency resources for uplink transmission from the second client device 100^". The network access node 300 is further configured to determine an uplink time-frequency resource conflict based on the allocated first uplink time-frequency resources and the obtained second uplink time-frequency resources. The network access node 300 is further configured to transmit an indication signal 504 to the first client device 100, wherein the indication signal 504 indicates that an uplink transmission from the second client device 100^' in the second uplink time-frequency resources at least partly overlaps with the first uplink time-frequency resources. The network access node 300 is further configured to monitor for an acknowledgement signal 506 associated with the indication signal 504 from the first client device 100.

Fig. 4 shows a flow chart of a corresponding method 400 which may be executed in a network access node 300, such as the one shown in Fig. 3. The method 400 comprises allocating 402 first uplink time-frequency resources for uplink transmission from a first client device 100. The method 400 further comprises receiving 404 a scheduling request from a second client device 100^' and obtain second uplink time-frequency resources for uplink transmission from the second client device 100^". The method 400 further comprises determining 406 an uplink time- frequency resource conflict based on the allocated first uplink time-frequency resources and the obtained second uplink time-frequency resources. The method 400 further comprises transmitting 408 an indication signal 504 to the first client device 100, wherein the indication signal 504 indicates that an uplink transmission from the second client device 100^' in the second uplink time-frequency resources at least partly overlaps with the first uplink time- frequency resources. The method 400 further comprises monitoring 410 for an acknowledgement signal 506 associated with the indication signal 504 from the first client device 100.

Fig. 5 shows a wireless communication system 500 according to an exemplary embodiment of the invention. The wireless communication system 500 comprises a first client device 100 and a network access node 300 configured to operate in the wireless communication system 500. For simplicity, the wireless communication system 500 shown in Fig. 5 only comprises one client device 100 and one network access node 300. However, the wireless communication system 500 may comprise any number of client devices 100 and any number of network access nodes 300 without deviating from the scope of the invention. The wireless communication system 500 further comprises a second client device 100^'.

As shown in Fig. 5, the first client device 100 receives a first uplink grant 502 from the network access node 300. The first uplink grant 502 indicates uplink transmission in first uplink time- frequency resources. The first client device 100 monitors for an indication signal 504 associated with the first uplink grant 502. The indication signal 504 indicates that an uplink transmission from the second client device 100^' in the second uplink time-frequency resources at least partly overlaps with the first uplink time-frequency resources. Upon detection of the indication signal 504 the first client device 100 transmits an acknowledgement signal 506 associated with the indication signal 504 to the network access node 300.

In embodiments of the invention, the first client device 100 is configured for a first type of service and the second client device 100^' is configured for a second type of service, and wherein the first type of service has lower priority than the second type of service. In an example, the first type of service is eMBB and the second type of service is URLLC.

Figs. 8a and 8b show some basic principles and advantages of embodiments of the invention. Mentioned embodiments are set in a 3GPP context hence the terminology and system design used. Therefore, a client device 100 corresponds to a UE and a network access node 300 to a gNB. In the description below, it is assumed a single eMBB UE (a UE using eMBB services), however the principles of UL PI also apply if multiple eMBB UEs are affected. More particularly, Fig. 8a shows uplink scheduling with UL PI and PI ACK. More particularly Fig. 8b shows advantages of the invention with UL scheduling with UL PI and PI ACK. If UL PI not detected, the NW node can send new SG to URLLC UE fast.

In Fig. 8a, the eMBB UE1 transmits a Scheduling Request (SR) to the gNB (NW node) and receives an UL grant, i.e. including time/frequency (f/t) resources to be used for UL transmission of data packet. During the preparation of the UL transmission in the UE1 or during the already ongoing transmission of UE1 , the gNB receives a SR from an URLLC UE2 (a UE using URLLC services). For fulfilling the latency and reliability requirements for the URLLC UE2 the gNB needs to allocate time/frequency resources overlapping with the allocated time/frequency resources in the UL grant for the eMBB UE1. Hence, the gNB transmits an UL PI to the eMBB UE1. The UL PI signals to the eMBB UE1 to stop/abandon transmissions in the time/frequency resources needed for the UL grant for the URLCC UE2. In addition, the gNB transmits an UL grant for the time/frequency resources to the URLCC UE2. This transmission of the UL grant to the URLLC UE2 may happen before or after receiving the PI ACK, as will be explained in the next paragraph. The eMBB UE1 , once detecting the UL PI, sends a PI ACK signal to the gNB, and discards or stops its UL transmission at least for the respective time/frequency resources. The gNB receives the ACK and will then be sure that the URLLC UE2 transmission will not be interfered.

The basic principles and advantages with this approach is shown in the second figure in Fig. 8, i.e. Fig. 8b. If the eMBB UE1 misses the UL PI, it will not transmit the PI ACK, and hence also not stop the UL transmission. Then there will be a collision between the eMBB UE1 and URLLC UE2 transmission. However, since the gNB does not receive an UL ACK, the gNB is aware of the possible UL collision, and can reschedule a new UL grant for the URLCC UE2 immediately and by that the retransmission can be made fast and scheduling latency can be reduced so URLLC UE2 delay constraints can be fulfilled.

In embodiments also covered by the invention, the gNB waits until PI ACKs from (all) affected eMBB UEs are received prior to sending an UL grant, that in order to be sure no UL collision will happen. Hence, this embodiment relates to the case when a multiple of eMBB UEs (corresponding to a multiple first client devices) are involved. Fig. 9 shows a flow chart of a UE embodiment of the invention. A first UE, that may be configured for a first type of service (say eMBB, with no strict latency requirements), receives an UL grant from the gNB and starts preparation of UL transmission according to the time/frequency resources in the UL grant in step 602.

The first UE also starts to monitor for an UL pre-emption indication PI in step 604. The PI may indicate that some or all UL resources granted to the first UE (i.e. eMBB UE) need to be released, since a second UE using a second type of service, such as URLLC with tight latency and reliability constraints, has higher priority in the UL transmission, and may need the already allocated UL resources.

The UL PI signal could be one of:

a. a unicast channel, for instance a control channel PDCCH (CORESET) for a first type of DCI with UE specific RNTI,

b. a broadcast channel for a first type of indication, for instance a broadcast PDCCH, c. a first type of DMRS of a PDCCH. The eMBB UE1 could monitor the DMRS of the PDCCH carrying the UL grant to UE2, and

d. an explicit signal.

Hence, in embodiments of the invention, monitor for the indication signal 504 comprises at least one of

monitor for the indication signal 504 in a physical downlink control channel;

monitor for the indication signal 504 in downlink control information;

monitor for the indication signal 504 in a broadcast control channel; and

monitor for the indication signal 504 in demodulation reference signals of a physical downlink control channel.

In the a-case above, the (the CRC of) the DCI may be scrambled with at least one of:

b. RNTI associated to the first UE,

c. RNTI associated to the second UE.

Hence, in embodiments of the invention, cyclic redundancy check of the downlink control information is scrambled with at least one of

a common radio network temporary identifier,

a radio network temporary identifier associated with the first UE, and

a radio network temporary identifier associated with a second UE. If the first UE (eMBB UE) does not detect a PI that is associated to the UL grant resources in step 606, the first UE transmits UL data according to the earlier received UL grant using well known prior art methods in step 608.

In case a PI is detected that is associated to the UL grant resources in step 606, the first UE transmits a PI ACK signal in step 608. Then discards/stops/abandons the UL transmission in at least part of the UL granted time/frequency resources determined by the UL PI in step 610. In other words, upon detection of the indication signal 504, the UE performs at least one of

• discard uplink transmission in at least one part of the first time-frequency resources;

• abandon uplink transmission in at least one part of the first time-frequency resources; and

• halt uplink transmission in at least one part of the first time-frequency resources.

The PI ACK signal could be transmitted on a PUCCH or in a PUSCH.

In an embodiment of the invention, the acknowledgement signal 506 is orthogonally coded with another signal in the physical uplink control channel.

In an embodiment of the invention, the PUSCH is punctured according to a pre-configuration for making room for the PI ACK signal. Hence, according to this embodiment, the acknowledgement signal 506 is transmitted in a physical uplink shared channel and the physical uplink shared channel is punctured according to a pre-configuration pattern so as to make room for the acknowledgement signal 506.

Since the PI ACK timing is critical, i.e. the time the first UE has to create the PI ACK signal may be very short. In order to overcome this, the first UE may pre-compute a PI ACK signal (assuming PI ACK resources known in advance by the UE), and hence once detecting the UL PI DCI the first UE just need to perform the transmission since the preparation of the signal is already performed, and by that the time between UL PI signal and PI ACK can be reduced.

Further, it is expected the ACK feedbacks are transmitted only from potential affected eMBB UEs who have been scheduled to transmit on the overlapped resources, and not all the eMBB UEs who are configured to monitor UL PI. It may potentially save uplink resources for this kind of UL PI ACK feedbacks.

In some embodiments, if the uplink resources for the UL PI ACK are not somehow preconfigured, then it could be included in the UL PI information, considering the timeline. And further the UL PI is sent through a group common RNTI, and further that multiple UEs have overlapped resources with that indicated by the UL PI. Then we might introduce a UE specific coding layer for the multiple UEs to transmit UL PI ACKs on the same physical resources. A UE derive the coding from its RNTI and apply it for the UL PI ACK feedback. So the network can sort out the different UE transmissions. Further, the UL PI ACK is carried on a PUCCH channel.

Fig. 10 shows a flow chart of a gNB embodiment of the invention. The gNB transmits an UL grant to a first UE (i.e. an eMBB UE) in step 702.

The gNB then receives a scheduling request from a second UE (i.e. a URLLC UE) in step 704 requiring high priority handling of the UL transmission. The gNB also determines that the URLLC UE needs to use resources already allocated to the first UE or several eMBB UEs in some embodiments.

The gNB sends UL grant to the second UE (URLLC UE) in step 706 and also a UL PI in step 708. In embodiments the gNB can be configured to send several UE specific UL Pis. The order of transmission may differ in different embodiments.

The gNB then monitors for a Pi ACK from the first UE in step 710. in embodiments it could be PI ACK from several eMBB UEs.

If a PI ACK is received from the first UE, i.e. YES in step 712 (received from all eMBB UEs expected to transmit PI ACKs)), the gNB knows that the transmission from the second UE is not interfered and hence can receive and detect URLLC UE data according to well-known techniques in step 716.

Hence, in embodiments of the invention, the gNB transmits a second uplink grant 502^' indicating the second uplink time-frequency resources to the second UE or second client device 100^' upon receiving the acknowledgement signal 506; and detects an uplink transmission from the second client device 100^' in response to transmitting the second uplink grant 502^' to the second client device 100^'.

However, if not all expected PI ACKs are determined, i.e. NO in step 712, the gNB can expect the URLLC UL transmission to be interfered by an eMBB UE not detecting the UL PI signal, and hence - most likely - will be erroneously decoded. In order to fulfill latency requirements, the gNB then retransmits a new UL grant to the second UE, possible prior to reception of the first URLLC packet in step 714.

Hence, in embodiments of the invention, the gNB transmits a further indication signal to the first UE upon not receiving the acknowledgement signal 506 within a predetermined timeframe.

In another embodiment of the gNB implementation, the gNB waits with transmission of the URLLC UL grant until it has received PI ACK from the affected eMBB UEs. This approach may delay the URLLC transmission, however, now the gNB knows there will be no UL interference, and thereby can, by using robust coding, make sure that a single UL transmission is sufficiently fulfilling the reliability requirement.

However, in yet another embodiment of the gNB implementation, the gNB transmits a second uplink grant 502^' indicating the second uplink time-frequency resources to the second client device 100^' before receiving the acknowledgement signal 506; and detects an uplink transmission from the second client device 100^' upon detecting the acknowledgement signal 506.

In yet another embodiment of the gNB implementation, the gNB obtains new second uplink time-frequency resources upon not receiving the acknowledgement signal 506 within a predetermined timeframe; and transmits a new second uplink grant 502^' indicating the new second uplink time-frequency resources to the second client device 100^'. Thereby, the second client device 100^' can be allocated interference free uplink resources if the gNB has not received the acknowledgement signal 506.

At least the following advantages are achieved with the present invention:

• Reliable UL PI design,

• Faster retransmission possible for gNB of URLLC packets in case of eMBB and URLLC data collision making it easier to fulfil URLLC latency requirements,

• Optimized spectrum utilization can be achieved by multiplexing URLLC and eMBB UEs in an efficient and reliable way,

• Avoiding the risk of missed UL PI (if the gNB waits for PI-ACK before granting the URLLC) and hence risk for UL collisions, by robust coding of URLLC packet increase the chances that the URLLC UL packet only need a single UL transmission (i.e. solving the delay requirement, by reducing the risk needing a retransmission.)

Further, avoiding the risk of missed UL PI (if the gNB waits for PI-ACK before granting the URLLC) and hence risk for UL collisions, by robust coding of URLLC packet increase the chances that the URLLC UL packet only need a single UL transmission, i.e. solving the delay requirement, by reducing the risk needing a retransmission.

To summarize some key points; a PI ACK signal which is transmitted by the eMBB UE in the UL as an acknowledgement of a detected UL PI signal transmitted from the gNB. The PI ACK signal can be transmitted in PUCCH or in PUSCH. In case of PUSCH transmission, PUSCH is punctured according to a pre-configuration for making room for the acknowledge signal.

The client device 100 herein, may be denoted as a user device, a User Equipment (UE), a mobile station, an internet of things (loT) device, a sensor device, a wireless terminal and/or a mobile terminal, is enabled to communicate wirelessly in a wireless communication system, sometimes also referred to as a cellular radio system. The UEs may further be referred to as mobile telephones, cellular telephones, computer tablets or laptops with wireless capability. The UEs in this context may be, for example, portable, pocket-storable, hand-held, computer- comprised, or vehicle-mounted mobile devices, enabled to communicate voice and/or data, via the radio access network, with another entity, such as another receiver or a server. The UE can be a Station (STA), which is any device that contains an IEEE 802.1 1 -conformant Media Access Control (MAC) and Physical Layer (PHY) interface to the Wireless Medium (WM). The UE may also be configured for communication in 3GPP related LTE and LTE-Advanced, in WiMAX and its evolution, and in fifth generation wireless technologies, such as New Radio.

The network access node 300 herein may also be denoted as a radio network access node, an access network access node, an access point, or a base station, e.g. a Radio Base Station (RBS), which in some networks may be referred to as transmitter,“gNB”,“gNodeB”,“eNB”, “eNodeB”,“NodeB” or“B node”, depending on the technology and terminology used. The radio network access nodes may be of different classes such as e.g. macro eNodeB, home eNodeB or pico base station, based on transmission power and thereby also cell size. The radio network access node can be a Station (STA), which is any device that contains an IEEE 802.1 1 -conformant Media Access Control (MAC) and Physical Layer (PHY) interface to the Wireless Medium (WM). The radio network access node may also be a base station corresponding to the fifth generation (5G) wireless systems.

Furthermore, any method according to embodiments of the invention may be implemented in a computer program, having code means, which when run by processing means causes the processing means to execute the steps of the method. The computer program is included in a computer readable medium of a computer program product. The computer readable medium may comprise essentially any memory, such as a ROM (Read-Only Memory), a PROM (Programmable Read-Only Memory), an EPROM (Erasable PROM), a Flash memory, an EEPROM (Electrically Erasable PROM), or a hard disk drive.

Moreover, it is realized by the skilled person that embodiments of the client device 100 and the network access node 300 comprises the necessary communication capabilities in the form of e.g., functions, means, units, elements, etc., for performing the solution. Examples of other such means, units, elements and functions are: processors, memory, buffers, control logic, encoders, decoders, rate matchers, de-rate matchers, mapping units, multipliers, decision units, selecting units, switches, interleavers, de-interleavers, modulators, demodulators, inputs, outputs, antennas, amplifiers, receiver units, transmitter units, DSPs, MSDs, TCM encoder, TCM decoder, power supply units, power feeders, communication interfaces, communication protocols, etc. which are suitably arranged together for performing the solution.

Especially, the processor(s) of the client device 100 and the network access node 300 may comprise, e.g., one or more instances of a Central Processing Unit (CPU), a processing unit, a processing circuit, a processor, an Application Specific Integrated Circuit (ASIC), a microprocessor, or other processing logic that may interpret and execute instructions. The expression“processor” may thus represent a processing circuitry comprising a plurality of processing circuits, such as, e.g., any, some or all of the ones mentioned above. The processing circuitry may further perform data processing functions for inputting, outputting, and processing of data comprising data buffering and device control functions, such as call processing control, user interface control, or the like.

Finally, it should be understood that the invention is not limited to the embodiments described above, but also relates to and incorporates all embodiments within the scope of the appended independent claims. For example, the following non-limiting embodiments of the invention are covered by the present disclosure.

A1. A first UE configured (for a first type of service) to

a. receive a UL grant (time/frequency resources for UL transmission),

b. monitor a physical channel for a first type of indication where the first type of indication indicates an UL transmission from a second UE (configured for a second type of service) in UL resources that at least partly overlap with the resources in the UL grant,

c. upon a detection of the first type of indication, transmit an acknowledge signal associated to the indication of the first type,

d. discard/abandon/halt UL transmission in at least parts of f/t resources in the UL grant. A2. The first UE according to A1 , configured to transmit the acknowledge signal on a PUCCH.

A3. The first UE according to A2, configured to transmit the acknowledge signal orthogonally coded (CDM for instance) towards another signal transmitted on the same PUCCH.

A4. The first UE according to A1 , configured to transmit the acknowledge signal in a PUSCH.

A5. The first UE according to A4, configured to puncture the PUSCH according to a preconfiguration for making room for the acknowledge signal.

A6. The first UE according to any of A1-A5 and where the monitoring of a physical channel for a first type of indication is monitoring one of

a. a control channel PDCCH (CORESET) for a first type of DCI,

b. a broadcast channel for a first type of indication,

c. a first type of DMRS of a PDCCH.

A7. The first UE according to any of A6a or A6b and where (the CRC of) the DCI is scrambled with at least one of

a. “common” RNTI (6b),

b. RNTI associated to the first UE (6a),

c. RNTI associated to the second UE (6a).

A8. The first UE according to any of A1-A7, and where the first type of service is a low priority service such as eMBB.

A9. The first UE according to any of A1-A8, and where the second type of service is a high priority service such as URLLC.

B1. A network access node, such as a gNB, configured to

a. receive a scheduling request, SR, from a second UE (configured for a second type of service) and obtain a first set of UL resources for the second UE,

b. determine an UL resource conflict based on the obtained first set of UL resources for the second UE and already allocated UL resources for at least a first UE (configured for a first type of service),

c. transmit to the first UE an indicator signal indicating an UL transmission from the second UE in UL resources that at least partly overlap with the already allocated resources for the first UE,

d. monitor for an acknowledge signal from the first UE, the acknowledge signal associated to the indicator signal. B2. The network access node according to B1 , configured to

a. upon reception of the acknowledge signal transmit an UL grant to the second UE granting the first set of UL resources;

b. detect the UL transmission from the second UE. B3. The network access node according to B2, configured to

a. upon not receiving of the acknowledge signal within a predetermined timeframe transmit a further indicator signal to the first UE.

B4. The network access node according to B1 , configured to

a. transmit a UL grant to the second UE granting the first set of UL resources even before receiving of the acknowledge signal;

b. upon receiving the acknowledge signal detect the UL transmission from the second UE.

B5. The network access node access node according to B4, configured to

a. upon not receiving of the acknowledge signal within a predetermined timeframe obtain a second set of UL resources for the second UE;

b. transmit a further UL grant to the second UE granting the second set of UL resources.

Claims

1. A first client device (100) for a wireless communication system (500), the first client device (100) being configured to

receive a first uplink grant (502) indicating uplink transmission in first uplink time- frequency resources;

monitor for an indication signal (504) associated with the first uplink grant (502); and transmit an acknowledgement signal (506) associated with the indication signal (504) upon detection of the indication signal (504).

2. The first client device (100) according to claim 1 , configured to, upon detection of the indication signal (504), perform at least one of

discard uplink transmission in at least one part of the first time-frequency resources; abandon uplink transmission in at least one part of the first time-frequency resources; and

3. The first client device (100) according to claim 1 or 2, wherein monitor for the indication signal (504) comprises at least one of

monitor for the indication signal (504) in a physical downlink control channel;

monitor for the indication signal (504) in downlink control information;

monitor for the indication signal (504) in a broadcast control channel; and

monitor for the indication signal (504) in demodulation reference signals of a physical downlink control channel.

4. The first client device (100) according to claim 3, wherein cyclic redundancy check of the downlink control information is scrambled with at least one of

a common radio network temporary identifier,

a radio network temporary identifier associated with the first client device (100), and a radio network temporary identifier associated with a second client device (100^").

5. The first client device (100) according to any one of the preceding claims, configured to transmit the acknowledgement signal (506) in a physical uplink control channel.

6. The first client device (100) according to claim 5, configured to

transmit the acknowledgement signal (506) orthogonally coded with another signal in the physical uplink control channel.

7. The first client device (100) according to any one of claims 1 to 4, configured to transmit the acknowledgement signal (506) in a physical uplink shared channel.

8. The first client device (100) according to claim 7, configured to

puncture the physical uplink shared channel according to a pre-configuration pattern so as to make room for the acknowledgement signal (506).

9. The first client device (100) according to any one of the preceding claims, wherein the indication signal (504) indicates an uplink transmission in second uplink time-frequency resources from a second client device (100^"), wherein the second uplink time-frequency resources at least partly overlap with the first uplink time-frequency resources.

10. The first client device (100) according to claim 9, wherein the first client device (100) is configured for a first type of service and the second client device (100^") is configured for a second type of service, and wherein the first type of service has lower priority than the second type of service.

1 1. The first client device (100) according to claim 10, wherein the first type of service is eMBB and the second type of service is URLLC.

12. A network access node (300) for a wireless communication system (500), the network access node (300) being configured to

allocate first uplink time-frequency resources for uplink transmission from a first client device (100);

receive a scheduling request from a second client device (100^") and obtain second uplink time-frequency resources for uplink transmission from the second client device (100^');

transmit an indication signal (504) to the first client device (100), wherein the indication signal (504) indicates that an uplink transmission from the second client device (100^") in the second uplink time-frequency resources at least partly overlaps with the first uplink time- frequency resources;

monitor for an acknowledgement signal (506) associated with the indication signal (504) from the first client device (100).

13. The network access node (300) according to claim 12, configured to transmit a second uplink grant (502^") indicating the second uplink time-frequency resources to the second client device (100^") upon receiving the acknowledgement signal (506);

detect an uplink transmission from the second client device (100^").

14. The network access node (300) according to claim 12 or 13, configured to

transmit a further indication signal to the first client device (100) upon not receiving the acknowledgement signal (506) within a predetermined timeframe.

15. The network access node (300) according to claim 12, configured to

transmit a second uplink grant (502^") indicating the second uplink time-frequency resources to the second client device (100^") before receiving the acknowledgement signal (506);

detect an uplink transmission from the second client device (100^") upon receiving the acknowledgement signal (506).

16. The network access node (300) according to any one of claims 12 to 15, configured to obtain new second uplink time-frequency resources upon not receiving the acknowledgement signal (506) within a predetermined timeframe;

transmit a new second uplink grant (502^") indicating the new second uplink time- frequency resources to the second client device (100^').

17. A method (200) for a first client device (100), the method (200) comprising

receiving (202) a first uplink grant (502) indicating uplink transmission in first uplink time- frequency resources;

monitoring (204) for an indication signal (504) associated with the first uplink grant (502); and

transmitting (206) an acknowledgement signal (506) associated with the indication signal (504) upon detection of the indication signal (504).

18. A method (400) for a network access node (300), the method (400) comprising

allocating (402) first uplink time-frequency resources for uplink transmission from a first client device (100);

receiving (404) a scheduling request from a second client device (100^") and obtain second uplink time-frequency resources for uplink transmission from the second client device (100^'); determining (406) an uplink time-frequency resource conflict based on the allocated first uplink time-frequency resources and the obtained second uplink time-frequency resources; transmitting (408) an indication signal (504) to the first client device (100), wherein the indication signal (504) indicates that an uplink transmission from the second client device (100^") in the second uplink time-frequency resources at least partly overlaps with the first uplink time-frequency resources;

monitoring (410) for an acknowledgement signal (506) associated with the indication signal (504) from the first client device (100).

19. A computer program with a program code for performing a method according to claim 17 or 18 when the computer program runs on a computer.