WO2020108726A1

WO2020108726A1 - Improving multi-connectivity in wireless communication networks

Info

Publication number: WO2020108726A1
Application number: PCT/EP2018/082538
Authority: WO
Inventors: Keeth Saliya JAYASINGHE LADDU; Zexian Li
Original assignee: Nokia Technologies Oy
Priority date: 2018-11-26
Filing date: 2018-11-26
Publication date: 2020-06-04

Abstract

According to an example aspect, there is provided a method comprising receiving, at the first wireless network node, a packet from a wireless terminal and, in response to determining that the packet was not received correctly at the first wireless network node, starting monitoring for reception of an indication from a second wireless network node, wherein the indication is associated with reception of the packet at the second wireless network node.

Description

IMPROVING MULTI-CONNECTIVITY IN WIRELESS COMMUNICATION

NETWORKS

FIELD [0001] Various example embodiments relate in general to wireless communication networks, and improving multi-connectivity in such networks.

BACKGROUND

[0002] In general, multi-connectivity refers to a feature in which a wireless terminal may be connected to, and communicating with, at least two wireless network nodes simultaneously. For example, multi- connectivity may be exploited in various cellular networks, such as, in cellular networks operating according to Long Term Evolution, LTE, and/or 5G radio access technology. 5G radio access technology may also be referred to as New Radio, NR, access technology. Since its inception, LTE has been widely deployed and 3rd Generation Partnership Project, 3GPP, still develops LTE. Similarly, 3GPP also develops standards for 5G/NR.

[0003] It is envisioned that in the near future there will be new services and new use cases for wireless communications, which require for example better reliability, lower latencies and/or higher data rates. Multi-connectivity may be utilized to address such needs, but there is a need to provide improved solutions for multi-connectivity to enable efficient operation of wireless communication networks.

SUMMARY

[0004] According to some example aspects, there is provided the subject-matter of the independent claims. Some example embodiments are defined in the dependent claims.

[0005] According to a first example aspect, there is provided a first method for a first wireless node comprising, receiving, at the first wireless network node, a packet from a wireless terminal and in response to determining that the packet was not received correctly at the first wireless network node, starting monitoring for reception of an indication from a second wireless network node, wherein the indication is associated with reception of the packet at the second wireless network node.

[0006] According to the first example aspect, the indication associated with reception of the packet may indicate a success of reception of the packet at the second wireless node.

[0007] According to the first example aspect, the indication associated with reception of the packet may indicate a successful reception of the packet or unsuccessful reception of the packet at the second wireless node.

[0008] According to the first example aspect, the first method may comprise, determining that the packet was not received correctly at the first wireless network node. According to the first example aspect, determining that the packet was not received correctly at the first wireless network node may also comprise detecting that decoding of the packet failed.

[0009] According to the first example aspect, the first method may comprise, receiving the indication, wherein the indication indicates unsuccessful reception of the packet at the second wireless network node and in response to receiving the indication, transmitting joint negative feedback, wherein the joint negative feedback comprises negative feedback associated with reception of the packet at the first network node and negative feedback associated with reception of the packet at the second network node.

[0010] According to the first example aspect, the first method may comprise, receiving a retransmitted version of the packet from the wireless terminal, receiving the indication, wherein the indication indicates successful reception of the packet at the second wireless network node and discarding the retransmitted version of the packet upon receiving the indication.

[0011] According to the first example aspect, the first method may comprise, determining a value of a timer for reception of the indication associated with reception of the packet from the second wireless network node.

[0012] According to the first example aspect, the first method may comprise, transmitting the value of the timer or a value associated with the timer to the wireless terminal. According to the first example aspect, the first method may also comprise, starting the timer in response to determining that the packet was not received correctly at the first wireless network node. In addition, or alternatively, the first method may comprise receiving the indication associated with reception of the packet from the second wireless network node while the timer is running. Also, in some example embodiments, the first method may comprise, after expiry of the timer and if no indication was received while the timer was running, transmitting an individual negative feedback associated with unsuccessful reception of the packet at the first wireless network node.

[0013] According to the first example aspect, the first method may comprise, in response to determining that the packet was not received correctly, transmitting negative feedback to the wireless terminal.

[0014] According to the first example aspect, the first method may comprise, receiving the indication, wherein the indication indicates unsuccessful reception of the packet at the second wireless network node and in response to receiving the indication, transmitting individual negative feedback, wherein the individual negative feedback comprises only negative feedback associated with reception of the packet at the first network node.

[0015] According to a second example aspect, there is provided a second method for a second wireless node comprising, receiving, at the second wireless network node, a packet from a wireless terminal and in response to determining whether the packet was received correctly at the second wireless network node, transmitting an indication to a first wireless network node, wherein the indication is associated with reception of the packet at the second wireless network node.

[0016] According to the second example aspect, the indication associated with reception of the packet may indicate a success of reception of the packet at the second wireless node.

[0017] According to the second example aspect, the indication associated with the packet may indicate a successful reception of the packet or unsuccessful reception of the packet at the second wireless node.

[0018] According to the second example aspect, the second method may comprise, determining whether the packet was received correctly at the second wireless network node. According to the second example aspect, the determining whether the packet was received correctly at the second wireless network node may comprise detecting whether decoding of the packet was successful.

[0019] According to the second example aspect, the second method may comprise, in response to determining that the packet was not received correctly, transmitting the indication, wherein the indication indicates unsuccessful reception of the packet at the second wireless network node.

[0020] According to the second example aspect, the second method may comprise, in response to determining that the packet was received correctly, transmitting the indication, wherein the indication indicates successful reception of the packet at the second wireless network node.

[0021] According to a third example aspect, there is provided an apparatus comprising at least one processing core, at least one memory including computer program code, the at least one memory and the computer program code being configured to, with the at least one processing core, cause the apparatus at least to perform the first method.

[0022] According to a fourth example aspect, there is provided an apparatus comprising at least one processing core, at least one memory including computer program code, the at least one memory and the computer program code being configured to, with the at least one processing core, cause the apparatus at least to perform the second method.

[0023] According to a fifth example aspect, there is provided an apparatus comprising means for performing the first method. According to a sixth example aspect, there is provided an apparatus comprising means for performing the second method.

[0024] According to a seventh example aspect, there is provided non-transitory computer readable medium having stored thereon a set of computer readable instructions that, when executed by at least one processor, cause an apparatus to at least perform the first method. According to an eighth example aspect, there is provided non-transitory computer readable medium having stored thereon a set of computer readable instructions that, when executed by at least one processor, cause an apparatus to at least perform the second method.

[0025] According to a ninth example aspect, there is provided a computer program configured to perform the first method. According to a tenth example aspect, there is provided a computer program configured to perform the second method. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIGURE 1 illustrates an exemplary network scenario in accordance with at least some example embodiments; [0027] FIGURE 2 illustrates a first example case in accordance with at least some example embodiments;

[0028] FIGURE 3 illustrates a second example case in accordance with at least some example embodiments;

[0029] FIGURE 4 illustrates an exemplary process in accordance with at least some example embodiments;

[0030] FIGURE 5 illustrates an example apparatus capable of supporting at least some example embodiments;

[0031] FIGURE 6 illustrates a flow graph of a first method in accordance with at least some example embodiments; [0032] FIGURE 7 illustrates a flow graph of a second method in accordance with at least some example embodiments.

EMBODIMENTS

[0033] Operation of wireless communication networks that exploit multi-connectivity may be improved by the procedures described herein. More specifically, a wireless communication network may comprise at least a wireless terminal, a first wireless network node and a second wireless network node. The wireless terminal may be connected to, and possibly communicating with, at least the first and the second wireless network node simultaneously. Said wireless terminal may transmit a packet to both, the first and the second wireless node. [0034] Upon reception of the packet, the second wireless network node may determine whether the packet was received correctly, or not, and transmit an indication to the first wireless network node. The indication may be associated with reception of the packet at the second wireless network node. Then, the first wireless network node may perform certain actions based a possible reception of the indication, to improve the operation of the wireless communication network. In general, the packet transmitted by the wireless terminal and received by the first and the second wireless network node may be an uplink packet, e.g., a data packet.

[0035] FIGURE 1 illustrates an exemplary network scenario in accordance with at least some example embodiments. According to the example scenario of FIGURE 1, there may be a cellular wireless communication system. The cellular wireless communication system may comprise at least one wireless terminal 110, first wireless network node 120, second wireless network node 130, and core network element 140. Wireless terminal 1 10 may be connected to, and possibly communicate with, first wireless network node 120 via air interface 115. In addition, wireless terminal 110 may be connected to, and possibly communicate with, second wireless network node 130 via air interface 125 at the same time.

[0036] Scenario of FIGURE 1 may be referred to as dual-connectivity. Dual connectivity may be seen as one form of multi-connectivity, wherein wireless terminal 1 10 may be connected to and, possibly communicate simultaneously with, two wireless network nodes. Multi-connectivity may then refer to a scenario, wherein wireless terminal 110 may be connected to and, possibly communicate simultaneously with, at least two wireless network nodes. In general, example embodiments may be used in wireless communication networks, wherein multi-connectivity is supported. Moreover, multi-connectivity, comprising dual- connectivity, may be exploited in connection with Packet Data Convergence Protocol, PDCP, duplication to enhance reliability.

[0037] Wireless terminal 110 may be, for example, a smartphone, a cellular phone, a User Equipment, UE, a Machine-to-Machine, M2M, node, Machine-Type Communications, MTC, node, an Internet of Things, IoT, node, a car telemetry unit, a laptop computer, a tablet computer or, indeed, any kind of suitable mobile station or wireless device. Air interface 115 between wireless terminal 110 and first wireless network node 120 may be configured in accordance with a first Radio Access Technology, RAT, which both wireless terminal 1 10 and first wireless network node 120 are configured to support. Moreover, wireless terminal 110 may also communicate with second wireless network node 130 over air interface 125 in accordance with the first RAT or some other RAT.

[0038] Examples of cellular RATs include Long Term Evolution, LTE, New Radio, NR, which may also be known as fifth generation, 5G, radio access technology and MulteFire. On the other hand, examples of non-cellular RATs include Wireless Local Area Network, WLAN, and Worldwide Interoperability for Microwave Access, WiMAX.

[0039] In case of cellular networks, wireless network nodes may be referred to as BSs. For example, in the context of LTE, a BS may be referred to as eNB while in the context of NR, a BS may be referred to as gNB. In case of both, LTE and NR, wireless terminal 110 may be referred to as a UE. So concerning FIGURE 1, in case of NR for instance, UE 110 may communicate wirelessly with a first gNB 120, or a cell of first gNB 120, via air interface 115 and with a second gNB 130, or a cell of second gNB 130, simultaneously via air interface 125. Also, for example in the context of WLAN, a wireless network node may be referred to as an access point. In some example embodiments, a wireless network node may be referred to as a Transmit-Receive Point, TRP, as well.

[0040] In any case, example embodiments are not restricted to any particular wireless technology. Instead, example embodiments may be exploited in any wireless system which uses multi-connectivity.

[0041] First wireless network node 120 and second wireless network node 130 may be connected, directly or via at least one intermediate node, with core network 140 via interface 135. Interface 135 may be a wired or wireless link. Interface 135 may be referred to as a backhaul link as well. In some example embodiments, the backhaul link may be a non-ideal backhaul link. For instance, if an ideal backhaul link would be defined as a link with optical fiber connection, then all other types of backhaul links may be considered as non-ideal backhaul links.

[0042] Moreover, core network 140 may be, in turn, coupled via interface 145 with another network (not shown in FIGURE 1), via which connectivity to further networks may be obtained, for example via a worldwide interconnection network.

[0043] Example embodiments may be exploited for example in 5G/NR cellular networks, which are envisioned to address new services and use cases. Such new services may not be only for human interaction, but also a huge growth in MTC related traffic is foreseen. The growth may be driven by, e.g., factory automation and flexible process control. As an example, Ultra-Reliable and Low-Latency Communications, URLLC, technology may be exploited for supporting such new services.

[0044] In case of URLLC technology, one stringent requirement is related to reliability. For instance, currently 3GPP considers reliability of 10 ⁶ for URLLC, i.e., maximum packet error rate should not be higher than 10 ⁶, while latency of radio communication may be bounded to 1 ms. Even shorter maximum latencies may be required as well, such as, 0.5 milliseconds. Maximum latency of radio communication may also include retransmissions.

[0045] Multi-connectivity may be exploited to improve reliability, i.e., to reduce packet error rate, for example for wireless terminals that are far away from a wireless network node. Such wireless terminals typically experience low Signal-to-Noise Ratios, SNRs. Radio links from a wireless terminal to different wireless network nodes may be different and hence, a transmission from a wireless terminal to multiple wireless network nodes may be received differently at different wireless network nodes. That is to say, if an uplink packet is transmitted to multiple network nodes, the likelihood that at least one of said multiple network nodes receives the uplink packet correctly is greater compared to a case, wherein the packet would be transmitted to only one wireless network node. Reliability may be thus improved by transmitting an uplink packet to at least two wireless network nodes, to improve likelihood of successful reception of the uplink packet. Also, latency may be improved as well, because the number of retransmissions is generally lower.

[0046] Nevertheless, improvements are anyway needed for multi-connectivity to enable efficient operation of the wireless communication network. For example, according to some example embodiments multiple wireless network nodes may perform follow up actions if an uplink packet is not received correctly. Such follow up actions may be designed by taking into account, e.g., latency requirements of a service that is used, such as a URLLC service.

[0047] In some example embodiments, multi-connectivity may refer to multi-TRP transmission/reception which may be used to improve successful reception rate of packets. As an example, in the context of multi-TRP/panel, performance may be improved using operations such as Coordinated Scheduling, CS, Coordinated Beamforming, CB, Dynamic Point Selection, DPS, and/or Dynamic Point Blanking, DPB, and multi-panel transmission. A multi-panel transmission/reception may refer to a case, wherein multiple antenna panels are used for transmission/reception and each panel comprises multiple antenna elements. Multi-panel transmission may be based on multi-panel codebook. However, such solutions may not be feasible in practical scenarios, at least if a non-ideal backhaul is used. Also, such solutions may not support further improvements of cell-edge and/or cell-average performance and better network coordination.

[0048] Example embodiments may provide an improved process related to the reception of uplink transmissions at multiple wireless network nodes and coordination between wireless network nodes. Moreover, when supporting joint reception of uplink transmissions, and especially considering various backhaul performance attributes such as latency, one challenge addressed by at least some example embodiments is how to design a feedback procedure for providing feedback related to uplink transmissions of a wireless terminal in an optimal way while taking into account requirements of services, such as the stringent requirements of URLLC services. [0049] In some example embodiments, the used frequency range may be above 6

GHz. For instance, such frequency range may be referred to as Frequency Range 2, FR2.

[0050] According to some example embodiments, multiple wireless network nodes may coordinate for transmitting feedback to a wireless terminal. Said feedback may be associated with an uplink packet transmitted by the wireless terminal, i.e., feedback may indicate whether the packet was received correctly at one or more of the wireless network nodes. The feedback may be referred to as negative feedback, if a retransmission is needed. In general, negative feedback may comprise, e.g., a Negative Acknowledgement, NACK, and/or an uplink grant for a retransmission of the uplink packet.

[0051] Moreover, the feedback may be individual or joint feedback, for example depending on how well the packet is received, performance of the backhaul link and a latency requirement of a service. Individual feedback may refer to a case, where each of multiple wireless network nodes transmits its own feedback. On the other hand, joint feedback may refer to a case, wherein one wireless network node transmits the feedback on behalf of at least one other wireless network node. [0052] Some example embodiments may therefore provide improved flexibility by providing an opportunity for sending individual feedback by an individual wireless network node, when desirable and feasible, while also enabling transmission of joint feedback.

[0053] The feedback may be implicit according to some example embodiments. For example, in case of a positive acknowledgement a wireless network node may decide not to transmit feedback to the wireless terminal. Thus, if a wireless terminal does not receive feedback, it may infer the lack of feedback as an Acknowledgement, ACK. On the other hand, feedback may be explicit according to some example embodiments. For example, negative feedback, such as a new uplink grant, may be transmitted by at least one of said multiple wireless network nodes for retransmission of the packet. Thus, a wireless terminal may infer a reception of the new uplink grant as a negative acknowledgement.

[0054] With reference to FIGURE 1 again, according to some example embodiments, if first wireless network node 120 and/or second wireless network node 130 receives a packet incorrectly from wireless terminal 110, the wireless network node in question may transmit negative feedback associated with the reception of the packet, e.g., a NACK and/or an uplink grant for a retransmission of the packet, to wireless terminal 110. That is to say, if for example first wireless network node 120 determines that the packet was not received correctly from wireless terminal 110, wireless network node 120 may transmit negative feedback to wireless terminal 110. The negative feedback for the retransmission of the packet may be transmitted right away, i.e., without waiting for an indication associated with reception of the packet from other wireless network nodes, such as, second wireless network node 130. Therefore, latency of the retransmission of the packet may be minimized, even though in some cases an unnecessary retransmission may be caused, if another wireless network node, such as second wireless network node 130, has received the packet correctly.

[0055] So in some example embodiments, first wireless network node 120 may, in response to determining that the packet was not received correctly, transmit negative feedback for a retransmission of the packet to wireless terminal 110 right away. Upon receiving the negative feedback, or in response to receiving, wireless terminal 110 may transmit a retransmitted version of the packet to first wireless network node, possibly using an uplink grant. Consequently, first wireless network node 120 may receive the retransmitted version of the packet. In some example embodiments, the retransmitted version of the packet may be received before receiving the indication about a successful reception of the packet at second wireless network node 130. So if the indication about a successful reception of the packet at second wireless network node 130 is received by first wireless network node 120 after receiving the retransmitted version of the packet, first wireless network node 120 may discard the received retransmitted version of the packet. That is to say, the received retransmitted version of the packet may be discarded in response to receiving the indication from second wireless network node 130, the indication indicating a successful reception of the packet at second wireless network node 130. Discarding the received retransmitted version of the packet reduces the load of the core network because first wireless network node 120 would not send the packet further.

[0056] Moreover, according to some example embodiments, unnecessary retransmission may be avoided by waiting for an indication from other wireless network nodes, wherein the indication may be associated with reception of the packet at other wireless network nodes. That is to say, in some example embodiments the negative feedback for the retransmission of the packet may not be transmitted right away. For example, first wireless network node 120 may wait for an indication from other wireless network nodes before transmitting the negative feedback. Other wireless network nodes, such as second wireless network node 130, may or may not have received, i.e., decoded, the packet correctly.

[0057] If second wireless network node 130 has decoded the packet correctly, it may inform other wireless network about successful, i.e., correct reception of the packet by transmitting an indication associated with reception of the packet at second wireless network node 130. Thus, if wireless network node 120 receives the indication, the indication indicating a successful reception at second wireless network node 130, wireless network node 120 may refrain from transmitting the negative feedback to avoid unnecessary retransmissions.

[0058] In some example embodiments, a timer may be used. The timer may refer to a time window for reception of an indication from second wireless network node 130, the indication being associated with reception of the packet at second wireless network node 130. For instance, the timer may be used if the backhaul link is non- ideal.

[0059] The timer may be referred to as a coordination timer as well in some example embodiments. The coordination timer, i.e., a value of the coordination timer, may be configured depending on a latency requirement of a service and latency of the backhaul link. In some example embodiments, a value of the coordination timer may be determined by first wireless network node 120 for reception of the indication from second wireless network node 130, wherein the packet may be received from wireless terminal 110.

[0060] Upon expiry of the timer, first wireless network node 120 may transmit individual negative feedback to wireless terminal, e.g., an uplink grant comprising a possible resource for a retransmission of the packet, if first wireless network node 120 did not receive the packet correctly from wireless terminal 110 and the indication indicated unsuccessful reception of the packet at second wireless node 130. The individual negative feedback may be transmitted also upon expiry of the timer, if first wireless network node 120 did not receive the packet correctly from wireless terminal 110 and no indication was received while the timer was running.

[0061] A value of the coordination timer may be determined, e.g., based on a latency budget of URLLC traffic of wireless terminal 110. In addition, or alternatively, the value of the coordination timer may be determined based on a latency of the backhaul link between first wireless network node 120 and second wireless network node 130. In addition, or alternatively, processing time of packets at wireless networks nodes 120 and 130 may be taken into account when determining the value of the coordination timer, for instance when wireless networks nodes 120 and 130 are TRPs.

[0062] According to some example embodiments, the timer may be exploited as follows. If first wireless network node 120 determines that the packet from wireless terminal 110 was not received correctly, i.e., reception was unsuccessful and first wireless network node 120 could not decode the packet correctly, first wireless network node 120 may start monitoring backhaul link 135 for reception of an indication from second wireless network node 130, wherein the indication may be associated with reception of the packet at second wireless network node 130.

[0063] However, if first wireless network node 120 does not receive the indication while the timer is running, first wireless network node 120 may send individual negative feedback to wireless terminal 110. That is to say, once the coordination timer expires and if first wireless network node 120 did not receive any indication associated with reception of the packet from other wireless network nodes, first wireless network node 120 may take an individualistic action, e.g., provide the individual negative feedback to wireless terminal 110. [0064] First wireless network node 120 may transmit individual negative feedback that comprises only information related to unsuccessful reception of the packet at first wireless network node 120. The individual negative feedback may comprise, e.g., a NACK and/or an uplink grant for a retransmission of the packet from wireless terminal 110 to first wireless network node 120.

[0065] On the other hand, if first wireless network node 120 receives the indication from second wireless network node 130 while the timer is running, the indication indicating a successful reception at second wireless network node 130, first wireless network node 120 may refrain from transmitting the individual negative feedback. On the other hand, if first wireless network node 120 has already transmitted the individual negative feedback and received a retransmitted version of the packet from wireless terminal 110, first wireless network node 120 may discard the retransmitted version of the packet in response to receiving the indication from second wireless network node 130, the indication indicating a successful reception at second wireless network node 130, thereby reducing load of the core network.

[0066] In some example embodiments, the value of the coordination timer, a value associated with the timer, such as a value associated with the value of the coordination timer or a value based on the value of the coordination timer, may be indicated to wireless terminal 110 by signalling. Said signalling may be semi-static or dynamic. For example, the value of the coordination timer may be transmitted to wireless terminal 110 by first wireless network node 120 or second wireless network node 130. Wireless terminal 110 may use the received value of the coordination timer. For example, wireless terminal 110 may stop monitoring a downlink channel, e.g., for a Downlink Control Information, DCI, during a time period when the coordination timer is running.

[0067] Communication between wireless network nodes 120 and 130 may be enabled during a time window when the coordination timer is running, i.e., after reception of the uplink packet and before expiry of the timer. In some example embodiments, a network may activate the coordination timer. The coordination timer may depend on traffic latency budget, latency of the backhaul link, etc. For instance, the coordination timer may be exploited in the context of URLLC, because different URLLC traffic classes may have different latency requirements or needs. [0068] If all wireless network nodes receive the packet correctly from wireless terminal 110, no negative feedback is sent for a retransmission of the packet from any of the wireless network nodes. Lack of transmission of negative feedback may be seen as an implicit positive feedback, i.e., ACK, by wireless terminal 110. That is to say, if wireless terminal 110 does not receive any feedback, it may infer that there is no need for a retransmission of a packet. Moreover, in such a case, no joint explicit positive feedback, e.g., ACK via Physical Downlink Control Channel, PDCCH, would be sent either.

[0069] In some example embodiments, first wireless network node 110 may transmit negative feedback if first wireless network node 110 determines that a packet received from a wireless terminal at the first wireless network node was not received correctly, e.g., by detecting that the first wireless network node was not able to decode the received packet correctly. For example, if the wireless terminal in question is a URLLC UE, which may typically have a low latency budget, first wireless network node 120 may transmit the negative feedback right away, i.e., in response to determining that the packet received from a wireless terminal was not received correctly.

[0070] On the other hand, if the latency budget is relaxed, e.g., for some UEs other than URLLC UEs, wireless network nodes may communicate about transmitting joint feedback to wireless terminal 110 and possibly also consider combining different version of the packet received at different wireless network nodes. For example, if second wireless node 130 determined that it did not receive the packet correctly, the communication between wireless network nodes may comprise transmitting an indication associated with reception the packet, by second wireless network node 130, to first wireless network node 120. Naturally, first wireless network node 120 may also transmit an indication associated with reception of the packet to second wireless network node 130 if first network node 120 determined that it did not receive the packet correctly.

[0071] In some example embodiments, communication between wireless network nodes may take place while the coordination timer is running. The coordination timer, or the value of the coordination timer, may be set according to an overall latency. The overall latency may comprise both, a latency requirement of the packet transmitted by the wireless terminal in addition to a latency requirement of the backhaul link and possible processing latency at different network nodes. Moreover, the latency of the backhaul link may comprise, for example, transmission and/or exchange of messages between the wireless network nodes. In addition, the latency of the backhaul link may comprise analysis time for possible joint negative feedback. In general, the latency of the backhaul link may be in accordance with a latency requirement of the packet transmitted by the wireless terminal in addition to a latency requirement of the backhaul link. If the overall latency is small, the value of the coordination timer may be small. However, if the overall latency is large, the value of the timer may be large.

[0072] If both, the first and the second wireless network, determine that they did not receive the packet transmitted by the wireless network node correctly, both wireless network nodes may wait for an indication associated with reception of the packet from other wireless network nodes. That is to say, both wireless network nodes may start monitoring for reception of the indication associated with reception of the packet and start the coordination timer. If the indication is received while the coordination timer is running, and the indication indicates unsuccessful reception, joint negative feedback such as a joint NACK and/or uplink grants may be transmitted. In general, the joint NACK and uplink grants may be referred to as joint negative feedback. In general, an uplink grant may comprise information about a resource allocated for a retransmission of the packet by the wireless terminal.

[0073] FIGURES 2 and 3 illustrate example cases, wherein two wireless network nodes determine that they have not received a packet from a wireless terminal correctly, i.e., decoding of the packet has failed. Both, FIGURE 2 and FIGURE 3, demonstrate a dual connectivity scenario, wherein wireless terminal 110 is connected to two wireless network nodes 120 and 130, and configured to transmit packets to wireless network nodes 120 and 130. Even though FIGURES 2 and 3 illustrate a dual-connectivity scenario, the example cases may be generalized for multi-connectivity as well, if there are more than two network nodes.

[0074] FIGURE 2 illustrates a first example case in accordance with at least some example embodiments. With reference to FIGURE 1 , wireless terminal 110 and first wireless network node 120 and second wireless network node 130 are shown in FIGURE 2. Moreover, FIGURE 2 demonstrates three stages 210, 220 and 230 according to the first example case.

[0075] At stage 210 of FIGURE 2, wireless terminal 110 may transmit packet 215 to first wireless network node 120 and second wireless network node 130. However, according to the first example case of FIGURE 2, first wireless network node 120 and second wireless network node 130 may not receive the packet correctly, e.g., decoding of the packet may fail.

[0076] In response to determining that the packet was not received correctly, wireless network nodes 120 and 130 may start monitoring for reception of an indication associated with reception the packet. For example, first wireless network node 120 may start monitoring a backhaul link for reception of an indication from second wireless network node 130, wherein the indication may be associated with reception of the packet at second wireless network node 130. Also, wireless network nodes 120 and 130 may start timer 222 in response to determining that the packet was not received correctly. Timer 222 may be referred to as a coordination timer in some example embodiments as well.

[0077] At stage 220 of FIGURE 2, communication 225 between first wireless network node 120 and second wireless network node 130 may take place. Communication 225 may be performed over a non-ideal backhaul, for example, within a time set by coordination timer 222. That is to say, communication 225 may take place while timer 222 is running. Communication 225 may comprise transmission of the indication from second wireless network node 130 to first wireless network node 120. Consequently, first wireless network node 120 may receive the indication from second wireless network node 130. The indication may be associated with reception of the packet at second wireless network node 130. In some example embodiments, the indication associated with reception of the packet may indicate a success of reception of the packet at second wireless node 130, such as successful reception of the packet at second wireless node 130.

[0078] Communication 225 may comprise an uplink grant for retransmission of the packet to second wireless network node 130. The uplink grant for retransmission of the packet to second wireless node 130 may be allocated by second wireless network node 130. Similarly, first wireless network node 120 may allocate an uplink grant for retransmission of the packet to first wireless network node 120.

[0079] In some example embodiments, communication 225 may comprise transmission of an indication from first wireless network node 120 to second wireless network node 130 as well. Consequently, second wireless network node 130 may receive the indication from first wireless network node 120, and the indication may be associated with reception of the packet at first wireless network node 120. [0080] Upon receiving communication 225 from second wireless network node 130, communication 225 comprising the indication associated with reception of the packet, first wireless network node 120 may decide to transmit joint negative feedback 235 to wireless terminal 110. The decision may be based on a preconfigured rule, for example, the preconfigured rule may indicate that wireless network node 120 should transmit the joint negative feedback. In such a case, wireless network node 120 may be referred to as a master BS. Alternatively, the decision may be based on a negotiation between wireless network nodes 120 and 130. Then, at stage 230, first wireless network node 120 may transmit joint negative feedback 235 to wireless terminal 1 10. Joint negative feedback may comprise, for example, NACKs associated with unsuccessful reception of the packet at wireless network nodes 120 and 130, and/or uplink grants for retransmission of the packet to wireless network nodes 120 and 130.

[0081] In some example embodiments, reliability of transmission of the joint negative feedback may be improved by transmitting the joint negative feedback from both, wireless network node 120 and wireless network node 130, to wireless terminal 110. Hence, both wireless network nodes 120 and 130 may, e.g., send a NACK together with at least one new uplink grant for a retransmission of the packet to wireless terminal 110. The at least one new uplink grant for a retransmission may be the same or different for wireless network nodes 120 and 130.

[0082] FIGURE 3 illustrates a second example case in accordance with at least some example embodiments. Again, with reference to FIGURE 1, wireless terminal 110 and first wireless network node 120 and second wireless network node 130 are shown in FIGURE 3 as well. Moreover, FIGURE 3 demonstrates three stages 310, 320 and 330 according to the second example case. Stage 310 of FIGURE 3 may correspond to stage 210 of FIGURE 2. Thus, wireless terminal 110 may transmit packet 315 to first wireless network node 120 and second wireless network node 130 at stage 310, but reception of packet 315 may be unsuccessful, similarly as in the first example case of FIGURE 2.

[0083] However, at stage 320 of FIGURE 3, there may be no communication 325 between first wireless network node 120 and second wireless network node 130. For example, wireless nodes may fail to communicate over a non-ideal backhaul within a time set by timer 322. That is to say, even if there would be communication 325, it may take place after coordination timer 322 has expired. If there is communication 325, it may correspond to communication 225 of FIGURE 2. However, wireless network nodes 120 and 130 may discard communication 325 because it is received upon expiry of timer 322. Timer 322 may be referred to as a coordination timer as well in some example embodiments.

[0084] Wireless network nodes 120 and 130 may thus determine that no indication associated with reception of the packet was received while timer 322 was running. Upon determining that no indication associated with reception of the packet was received while timer 322 was running, both wireless network nodes 120 and 130 may transmit individual negative feedback 335 and 345, respectively, to wireless terminal 110. Individual negative feedback 335, 345 may be associated with the packet, e.g., indicating unsuccessful reception at wireless network nodes. That is to say, for example first wireless network node 120 may transmit, at stage 330, individual negative feedback 335 to wireless terminal 110. Also, second wireless network node 130 may transmit, at stage 330, individual negative feedback 345 to wireless terminal 110. Individual negative feedback 335, 345 may be, for example, a NACK or an uplink grant for a retransmission of the packet.

[0085] Some example embodiments thus provide an improved feedback scheme for downlink, for carrying negative feedback related to a success of reception of an uplink transmission, possibly over PDCCH. The negative feedback scheme may be particularly advantageous for feeding back information related to uplink transmissions of URLLC packets. In some example embodiments, the backhaul link between at least two wireless network nodes, such as TRPs, may be non-ideal.

[0086] Use of the joint negative feedback provides resource savings, e.g., for URLLC.

Example embodiments enable fast individual negative feedbacks for low latency services, but if the time allows, joint negative feedback may be exploited to save resources. On the other hand, if the latency requirement is strict, a wireless network node may allocate resource and ask for a retransmission of the packet from the wireless terminal right away. Thus, some example embodiments provide a flexible way of coordination between wireless networks to transmit individual and, possibly joint, negative feedbacks.

[0087] LIGURE 4 illustrates an exemplary process in accordance with at least some example embodiments. The exemplary process of FIGURE 4 may be performed by a wireless network node, such as wireless network node 120 or 130 of FIGURE 1, or a wireless network node may be configured to perform the process. As an example, the wireless network node may be a TRP or a BS, such as a gNB. [0088] The exemplary process of FIGURE 4 may start at step 400. At step 410, a packet may be received from a wireless terminal. Hence, the packet may be an uplink packet. Furthermore, the process may comprise, at step 420, determining whether the packet was received correctly, e.g., by determining whether decoding of the packet was successful. In response to determining that the packet was received correctly, the process may comprise at step 425, transmitting an indication associated with reception the packet, wherein the indication indicates a successful reception of the packet at the wireless network node. The indication may be transmitted to other wireless network nodes via a backhaul link, e.g., via a non-ideal backhaul link. However, if it is determined at step 420 that the packet was not received correctly, the process may comprise starting a coordination timer.

[0089] The process may also comprise, at step 430, starting monitoring for reception of an indication from a second wireless network node if it is determined at step 420 that the packet was not received correctly. The indication may be associated with reception of the packet at the second wireless network node, i.e., the indication may indicate a success of reception of the packet. That is to say, step 430 may comprise checking for a successful reception indication from other wireless network nodes, such as the second wireless network node, wherein the indication may be associated with reception of the packet at the second wireless network node.

[0090] The process may further comprise, at step 440, checking whether the successful reception indication associated with reception of the packet is received while a coordination timer is running. If the successful reception indication is received, the process may comprise, at step 445, determining that there is no need to transmit negative feedback associated with the packet, e.g., an uplink grant for a retransmission of a packet. Alternatively, if negative feedback has been transmitted already and a retransmitted version of the packet has been received from the wireless terminal, the process may comprise discarding the retransmitted version of the packet, at step 445. That is to say, the retransmitted version of the packet may be discarded in response to receiving the successful reception indication.

[0091] On the other hand, if the successful reception indication is not received, the process may comprise, at step 450, determining whether the coordination timer has expired, i.e., checking whether the coordination timer is still running. If the coordination timer has not expired yet, the process may move back to step 440, for checking again whether the successful reception indication is received.

[0092] Furthermore, if it is determined at step 450 that the cooperation timer has expired, the process may proceed to step 460. The process may comprise, at step 460, transmitting negative feedback to the wireless terminal. The negative feedback may comprise a NACK and/or an uplink grant for a retransmission of the packet. The negative feedback may be referred to as an individual negative feedback if no indication was received at step 440. However, if an indication was received at step 440, the indication indicating unsuccessful reception of the packet at another wireless network node, the negative feedback may be a joint negative feedback.

[0093] FIGURE 5 illustrates an example apparatus capable of supporting at least some example embodiments. Illustrated is device 500, which may comprise, for example, first wireless network node 120 or second wireless network node 130 of FIGURE 1. Comprised in device 500 is processor 510, which may comprise, for example, a single- or multi-core processor wherein a single-core processor comprises one processing core and a multi-core processor comprises more than one processing core. Processor 510 may comprise, in general, a control device. Processor 510 may comprise more than one processor. Processor 510 may be a control device. A processing core may comprise, for example, a Cortex- A8 processing core manufactured by ARM Holdings or a Steamroller processing core produced by Advanced Micro Devices Corporation. Processor 510 may comprise at least one Qualcomm Snapdragon and/or Intel Atom processor. Processor 510 may comprise at least one application-specific integrated circuit, ASIC. Processor 510 may comprise at least one field- programmable gate array, FPGA. Processor 510 may be means for performing method steps in device 500. Processor 510 may be configured, at least in part by computer instructions, to perform actions.

[0094] A processor may comprise circuitry, or be constituted as circuitry or circuitries, the circuitry or circuitries being configured to perform phases of methods in accordance with example embodiments described herein. As used in this application, the term“circuitry” may refer to one or more or all of the following: (a) hardware-only circuit implementations, such as implementations in only analog and/or digital circuitry, and (b) combinations of hardware circuits and software, such as, as applicable: (i) a combination of analog and/or digital hardware circuit(s) with software/firmware and (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and (c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

[0095] This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular wireless device, or other computing or network device.

[0096] Device 500 may comprise memory 520. Memory 520 may comprise random- access memory and/or permanent memory. Memory 520 may comprise at least one RAM chip. Memory 520 may comprise solid-state, magnetic, optical and/or holographic memory, for example. Memory 520 may be at least in part accessible to processor 510. Memory 520 may be at least in part comprised in processor 510. Memory 520 may be means for storing information. Memory 520 may comprise computer instructions that processor 510 is configured to execute. When computer instructions configured to cause processor 510 to perform certain actions are stored in memory 520, and device 500 overall is configured to run under the direction of processor 510 using computer instructions from memory 520, processor 510 and/or its at least one processing core may be considered to be configured to perform said certain actions. Memory 520 may be at least in part comprised in processor 510. Memory 520 may be at least in part external to device 500 but accessible to device 500.

[0097] Device 500 may comprise a transmitter 530. Device 500 may comprise a receiver 540. Transmitter 530 and receiver 540 may be configured to transmit and receive, respectively, information in accordance with at least one cellular or non-cellular standard. Transmitter 530 may comprise more than one transmitter. Receiver 540 may comprise more than one receiver. Transmitter 530 and/or receiver 540 may be configured to operate in accordance with Global System for Mobile communication, GSM, Wideband Code Division Multiple Access, WCDMA, 5G, Long Term Evolution, LTE, IS-95, Wireless Local Area Network, WLAN, Ethernet and/or Worldwide Interoperability for Microwave Access, WiMAX, standards, for example.

[0098] Device 500 may comprise a Near-Field Communication, NFC, transceiver 550. NFC transceiver 550 may support at least one NFC technology, such as Bluetooth, Wibree or similar technologies.

[0099] Device 500 may comprise User Interface, UI, 560. UI 560 may comprise at least one of a display, a keyboard, a touchscreen, a vibrator arranged to signal to a user by causing device 500 to vibrate, a speaker and a microphone. A user may be able to operate device 500 via UI 560, for example to accept incoming telephone calls, to originate telephone calls or video calls, to browse the Internet, to manage digital files stored in memory 520 or on a cloud accessible via transmitter 530 and receiver 540, or via NFC transceiver 550, and/or to play games.

[00100] Device 500 may comprise or be arranged to accept a user identity module 570. User identity module 570 may comprise, for example, a Subscriber Identity Module, SIM, card installable in device 500. A user identity module 570 may comprise information identifying a subscription of a user of device 500. A user identity module 570 may comprise cryptographic information usable to verify the identity of a user of device 500 and/or to facilitate encryption of communicated information and billing of the user of device 500 for communication effected via device 500.

[00101] Processor 510 may be furnished with a transmitter arranged to output information from processor 510, via electrical leads internal to device 500, to other devices comprised in device 500. Such a transmitter may comprise a serial bus transmitter arranged to, for example, output information via at least one electrical lead to memory 520 for storage therein. Alternatively to a serial bus, the transmitter may comprise a parallel bus transmitter. Fikewise processor 510 may comprise a receiver arranged to receive information in processor 510, via electrical leads internal to device 500, from other devices comprised in device 500. Such a receiver may comprise a serial bus receiver arranged to, for example, receive information via at least one electrical lead from receiver 540 for processing in processor 510. Alternatively to a serial bus, the receiver may comprise a parallel bus receiver. [00102] Device 500 may comprise further devices not illustrated in FIGURE 5. For example, where device 500 comprises a smartphone, it may comprise at least one digital camera. Some devices 500 may comprise a back-facing camera and a front-facing camera, wherein the back-facing camera may be intended for digital photography and the front facing camera for video telephony. Device 500 may comprise a fingerprint sensor arranged to authenticate, at least in part, a user of device 500. In some example embodiments, device 500 lacks at least one device described above. For example, some devices 500 may lack a NFC transceiver 550 and/or user identity module 570.

[00103] Processor 510, memory 520, transmitter 530, receiver 540, NFC transceiver 550, UI 560 and/or user identity module 570 may be interconnected by electrical leads internal to device 500 in a multitude of different ways. For example, each of the aforementioned devices may be separately connected to a master bus internal to device 500, to allow for the devices to exchange information. However, as the skilled person will appreciate, this is only one example and depending on the example embodiment various ways of interconnecting at least two of the aforementioned devices may be selected without departing from the scope of the example embodiments.

[00104] FIGURE 6 is a flow graph of a first method in accordance with at least some example embodiments. The phases of the illustrated first method may be performed by first wireless network node 120, such as a BS or a TRP, or by a control device configured to control the functioning thereof, possibly when installed therein.

[00105] The first method may comprise, at phase 610, receiving at a first wireless network node, a packet from a wireless terminal. The first method may also comprise, at phase 620, in response to determining that the packet was not received correctly at the first wireless network node, starting monitoring for reception of an indication from a second wireless network node, wherein the indication is associated with reception of the packet at the second wireless network node.

[00106] In some example embodiments, the first method may comprise transmitting negative feedback to the wireless terminal depending on whether the indication is received. For example, the first method may comprise transmitting individual or joint feedback depending on whether the indication is received. Individual feedback may be transmitted if the indication is not received while joint feedback may be transmitted if the indication is received. [00107] FIGURE 7 is a flow graph of a second method in accordance with at least some example embodiments. The phases of the illustrated first method may be performed by second wireless network node 130, such as a BS or a TRP, or by a control device configured to control the functioning thereof, possibly when installed therein.

[00108] The second method may comprise, at phase 710, receiving, at a second wireless network node, a packet from a wireless terminal. The second method may also comprise, at phase 720, in response to determining whether the packet was received correctly at the second wireless network node, transmitting an indication to a first wireless network node, wherein the indication is associated with reception of the packet at the second wireless network node.

[00109] It is to be understood that the example embodiments disclosed are not limited to the particular structures, process steps, or materials disclosed herein, but are extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular example embodiments only and is not intended to be limiting.

[00110] Reference throughout this specification to one example embodiment or an example embodiment means that a particular feature, structure, or characteristic described in connection with the example embodiment is included in at least one example embodiment. Thus, appearances of the phrases “in one example embodiment” or “in an example embodiment” in various places throughout this specification are not necessarily all referring to the same example embodiment. Where reference is made to a numerical value using a term such as, for example, about or substantially, the exact numerical value is also disclosed.

[00111] As used herein, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, various example embodiments and examples may be referred to herein along with alternatives for the various components thereof. It is understood that such example embodiments, examples, and alternatives are not to be construed as de facto equivalents of one another, but are to be considered as separate and autonomous representations. [00112] In an exemplary embodiment, an apparatus, such as, for example first wireless network node 120 or second wireless network node 130, such as a BS or a TRP, or by a control device configured to control the functioning thereof, possibly when installed therein, may comprise means for carrying out the example embodiments described above and any combination thereof

[00113] In an exemplary embodiment, a computer program may be configured to cause a method in accordance with the example embodiments described above and any combination thereof. In an exemplary embodiment, a computer program product, embodied on a non-transitory computer readable medium, may be configured to control a processor to perform a process comprising the example embodiments described above and any combination thereof

[00114] In an exemplary embodiment, an apparatus, such as, for example first wireless network node 120 or second wireless network node 130, such as a BS or a TRP, or by a control device configured to control the functioning thereof, possibly when installed therein, may comprise at least one processor, and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to perform the example embodiments described above and any combination thereof

[00115] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more example embodiments. In the preceding description, numerous specific details are provided, such as examples of lengths, widths, shapes, etc., to provide a thorough understanding of example embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.

[00116] While the forgoing examples are illustrative of the principles of the example embodiments in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the invention. Accordingly, it is not intended that the invention be limited, except as by the claims set forth below. [00117] The verbs“to comprise” and“to include” are used in this document as open limitations that neither exclude nor require the existence of also un-recited features. The features recited in depending claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of“a” or“an”, that is, a singular form, throughout this document does not exclude a plurality.

INDUSTRIAL APPLICABILITY

[00118] At least some example embodiments find industrial application in wireless communication networks, wherein it is desirable to exploit multi-connectivity.

ACRONYMS LIST

3 GPP 3^rd Generation Partnership Project

ACK Acknowledgement

BS Base Station

DBS Dynamic Point Blanking

DCI Downlink Control Information

DPS Dynamic Point Selection, DPS

FR2 Frequency Range 2

GSM Global System for Mobile communication IoT Internet of Things

LTE Long-Term Evolution

M2M Machine-to -Machine

MTC Machine-type Communications

NACK Negative Acknowledgement

NFC Near-Field Communication

NR New Radio

PDCCH Physical Downlink Control Channel RAT Radio Access Technology

SIM Subscriber Identity Module

TRP Transmit-Receive Point

UE User Equipment

UI User Interface URLLC Ultra-Reliable and Low-Latency Communications

WCDMA Wideband Code Division Multiple Access

WiMAX Worldwide Interoperability for Microwave Access

WLAN Wireless Local Area Network

REFERENCE SIGNS LIST

Claims

CLAIMS:

1. A method for a first wireless network node, comprising:

- receiving, at the first wireless network node, a packet from a wireless terminal; and

- in response to determining that the packet was not received correctly at the first wireless network node, starting monitoring for reception of an indication from a second wireless network node, wherein the indication is associated with reception of the packet at the second wireless network node.

2. A method according to claim 1, wherein the indication associated with reception of the packet indicates a success of reception of the packet at the second wireless node.

3. A method according to claim 1 or claim 2, wherein the indication associated with reception of the packet indicates a successful reception of the packet or unsuccessful reception of the packet at the second wireless node.

4. A method according to any of the preceding claims, further comprising:

- determining that the packet was not received correctly at the first wireless network node.

5. A method according to claim 4, wherein said determining that the packet was not received correctly at the first wireless network node comprises detecting that decoding of the packet failed.

6. A method according to any of the preceding claims, further comprising:

- receiving the indication, wherein the indication indicates unsuccessful reception of the packet at the second wireless network node; and

- in response to receiving the indication, transmitting joint negative feedback, wherein the joint negative feedback comprises negative feedback associated with reception of the packet at the first network node and negative feedback associated with reception of the packet at the second network node.

7. A method according to any of the preceding claims, further comprising: - receiving a retransmitted version of the packet from the wireless terminal;

- receiving the indication, wherein the indication indicates successful reception of the packet at the second wireless network node; and

- discarding the retransmitted version of the packet upon receiving the indication.

8. A method according to any of the preceding claims, further comprising:

- determining a value of a timer for reception of the indication associated with reception of the packet from the second wireless network node.

9. A method according to claim 8, further comprising:

- transmitting the value of the timer, or a value associated with the timer, to the wireless terminal.

10. A method according to claim 8 or claim 9, further comprising:

- starting the timer in response to determining that the packet was not received correctly at the first wireless network node.

11. A method according to any of claims 8 - 10, further comprising:

- receiving the indication associated with reception of the packet from the second wireless network node while the timer is running.

12. A method according to any of claims 8 - 11, further comprising:

- after expiry of the timer and if no indication was received while the timer was running, transmitting an individual negative feedback associated with unsuccessful reception of the packet at the first wireless network node.

13. A method according to any of the preceding claims, further comprising:

- in response to determining that the packet was not received correctly, transmitting negative feedback to the wireless terminal.

14. A method according to any of the preceding claims, further comprising:

- receiving the indication, wherein the indication indicates unsuccessful reception of the packet at the second wireless network node; and - in response to receiving the indication, transmitting individual negative feedback, wherein the individual negative feedback comprises only negative feedback associated with reception of the packet at the first network node.

15. A method for a second wireless network node, comprising:

- receiving, at the second wireless network node, a packet from a wireless terminal; and

- in response to determining whether the packet was received correctly at the second wireless network node, transmitting an indication to a first wireless network node, wherein the indication is associated with reception of the packet at the second wireless network node.

16. A method according to claim 15, wherein the indication associated with reception of the packet indicates a success of reception of the packet at the second wireless node.

17. A method according to claim 15 or claim 16, wherein the indication associated with the packet indicates a successful reception of the packet or unsuccessful reception of the packet at the second wireless node.

18. A method according to any of claims 15 - 17, further comprising:

- determining whether the packet was received correctly at the second wireless network node.

19. A method according to claim 18, wherein the determining whether the packet was received correctly at the second wireless network node comprises detecting whether decoding of the packet was successful.

20. A method according to any of claims 15 - 19, further comprising:

- in response to determining that the packet was not received correctly, transmitting the indication, wherein the indication indicates unsuccessful reception of the packet at the second wireless network node.

21. A method according to any of claims 15 - 20, further comprising: - in response to determining that the packet was received correctly, transmitting the indication, wherein the indication indicates successful reception of the packet at the second wireless network node.

22. An apparatus comprising at least one processing core, at least one memory including computer program code, the at least one memory and the computer program code being configured to, with the at least one processing core, cause the apparatus at least to perform:

- receive, at the first wireless network node, a packet from a wireless terminal; and

- in response to determining that the packet was not received correctly at the first wireless network node, start monitoring for reception of an indication from a second wireless network node, wherein the indication is associated with reception of the packet at the second wireless network node.

23. An apparatus according to claim 22, wherein the at least one memory and the computer program code are further configured to, with the at least one processing core, cause the apparatus at least to perform a method according to any of claims 2 - 14.

24. An apparatus comprising at least one processing core, at least one memory including computer program code, the at least one memory and the computer program code being configured to, with the at least one processing core, cause the apparatus at least to perform:

- receive, at the second wireless network node, a packet from a wireless terminal; and

- in response to determining whether the packet was received correctly at the second wireless network node, transmit an indication to a first wireless network node, wherein the indication is associated with reception of the packet at the second wireless network node.

25. An apparatus according to claim 24, wherein the at least one memory and the computer program code are further configured to, with the at least one processing core, cause the apparatus at least to perform a method according to any of claims 16 - 21.

26. An apparatus comprising:

- means for receiving, at the first wireless network node, a packet from a wireless terminal; and - means for, in response to determining that the packet was not received correctly at the first wireless network node, starting monitoring for reception of an indication from a second wireless network node, wherein the indication is associated with reception of the packet at the second wireless network node.

27. An apparatus according to claim 26, further comprising means for performing a method according to any of claims 2 -14.

28. An apparatus comprising:

- means for receiving, at the second wireless network node, a packet from a wireless terminal; and

- means for, in response to determining whether the packet was received correctly at the second wireless network node, transmitting an indication to a first wireless network node, wherein the indication is associated with reception of the packet at the second wireless network node.

29. An apparatus according to claim 28, further comprising means for performing a method according to any of claims 16- 21.

30. A non-transitory computer readable medium having stored thereon a set of computer readable instructions that, when executed by at least one processor, cause an apparatus to at least perform a method according to any of claims 1 - 14 or 15 - 21.

31. A computer program configured to perform a method according to any of claims 1 - 14 or 15 - 21.