Method and apparatus for link adaptation in a mixed traffic environment

The present disclosure provides a method for performing link adaptation at a network node in a wireless communication network, which may include identifying first traffic and second traffic included in transmission between the network node and a user equipment, wherein the first traffic is related to first service having a first quality of service (QoS) requirement, and the second traffic is related to second service having a second QoS requirement; and applying a first link adaptation loop catering for the first QoS requirement to the first traffic, and applying a second link adaptation loop catering for the second QoS requirement to the second traffic. In one example, the second link adaptation loop is independent from the first link adaptation loop. In another example, the second link adaptation loop is dependent on the first link adaptation loop.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Submission Under 35 U.S.C. § 371 for U.S. National Stage Patent Application of International Application Number: PCT/CN2017/092947, filed Jul. 14, 2017 entitled “METHOD AND APPARATUS FOR LINK ADAPTATION IN A MIXED TRAFFIC ENVIRONMENT,” the entirety of which is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure generally relates to the technical field of wireless communication, and in particular to method and apparatus for performing link adaptation in a wireless communication network.

BACKGROUND

This section is intended to provide a background to the technologies described in this disclosure. Unless otherwise indicated herein, what is described in this section should not be regarded as prior art and are not admitted to be prior art by inclusion in this section.

Link adaptation is an important function in a wireless communication system. In a Long Term Evolution (LTE) system, the purpose of link adaptation is to determine a Modulation and Coding Scheme (MCS) that will maximize a transmitter's data rate under a given radio link condition. In a typical system that implements a retransmission scheme, e.g., a Hybrid Automatic Repeat Request (HARQ) scheme, the link adaptation process is designed to select the highest MCS with which a target Block Error Rate (BLER) can be achieved after a number of transmissions. Typically, the MCS is selected for each transport block, which is transmitted every Transmission Time Interval (TTI). The LTE system treats all the transmitted traffic in the same way as Internet Protocol (IP) data and follows the same protocol and algorithms at higher layers such as e.g. Transmission Control Protocol (TCP) or User Datagram Protocol (UDP) regardless of traffic type. It simplifies hardware implementation and maintenance for the LTE system.

The continuing evolution from LTE to 5G (the fifth generation of mobile telecommunication and wireless technology) opens up the possibility of introducing an entirely new air interface which is also referred to as New Radio (NR), and creating network architecture and designs that are not necessarily backward compatible with LTE. 5G is envisaged to expand and support diverse usage scenarios and applications. Accordingly, the NR needs to support multiple types of services which may likely have very different service requirements.

The conventional link adaptation scheme, e.g. those used in the LTE system, cannot meet the requirement for diverse usage scenarios and applications arising in the evolution from LTE to 5G, and in 5G network.

SUMMARY

It is therefore an object of the present disclosure to improve link adaptation, in particular, to provide some solutions for link adaptation to cope with a mixed traffic environment.

According to one aspect of the present disclosure, there is provided a method for performing link adaptation at a network node in a wireless communication network, which may comprise identifying first traffic and second traffic included in transmission between the network node and a user equipment (UE), wherein the first traffic is related to first service having a first quality of service (QoS) requirement, and the second traffic is related to second service having a second QoS requirement; and applying a first link adaptation loop catering for the first QoS requirement to the first traffic, and applying a second link adaptation loop catering for the second QoS requirement to the second traffic.

In one exemplary embodiment, the second link adaptation loop is independent from the first link adaptation loop.

In another exemplary embodiment, the second link adaptation loop is dependent on the first link adaptation loop.

According to another aspect of the present disclosure, there is provided a network node in a wireless communication network, which may comprise a communication interface configured to perform communication with a UE, a processor, and a memory containing instructions that when executed cause the processor to perform any of the methods in the present disclosure.

According to still another aspect of the present disclosure, there is provided a network node in a wireless communication network configured for performing link adaptation for traffic included in transmission between the network node and a UE. The network node may comprise a communication interface and a processing circuitry. Said processing circuitry may be configured to cause the network node to identify first traffic and second traffic included in transmission between the network node and a UE, wherein the first traffic is related to first service having a first QoS requirement, and the second traffic is related to second service having a second QoS requirement; and apply a first link adaptation loop catering for the first QoS requirement to the first traffic, and apply a second link adaptation loop catering for the second QoS requirement to the second traffic.

According to still another aspect of the present disclosure, there is provided a computer program comprising computer program code which, when executed in a network node, causes the network node to perform any of the methods in the present disclosure. According to another aspect of the present disclosure, there is provided a carrier containing said computer program.

According to still another aspect of the present disclosure, there is provided an apparatus for performing link adaptation in a wireless communication network, comprising modules for performing each step in any of the methods in the present disclosure.

The solutions as provided in the present disclosure can concurrently meet the different requirements of different services in the mixed traffic environment, by means of multiple link adaptation loops catering for different service requirements. Moreover, the solutions in the present disclosure can be flexibly adapted to various mixed traffic patterns, for example, where two traffic are multiplexed together, but one traffic is much sparser than another traffic.

Other embodiments and the further advantages thereof are discussed in details hereinafter.

DETAILED DESCRIPTION OF EMBODIMENTS

In the following description, numerous specific details are set forth in embodiments. It will be appreciated, however, by persons skilled in the art that the embodiments as disclosed herein may be practiced without such specific details, and that other changes may be made, without departing from the spirit or scope of the subject matters presented here. In other instances, well-known circuits, structures and techniques have not been shown in detail in order not to obscure the understanding of the present disclosure.

References to the phrases “one embodiment”, “an embodiment”, “an example embodiment” and the like throughout the disclosure indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment.

In the present disclosure, a link adaptation loop may refer to software (e.g. algorithm), hardware, combination of software and hardware, or functional module for performing link adaptation of uplink and/or downlink.

Hereinafter, some embodiments of the present disclosure are discussed in the context of 5G network and New Radio (NR). However, persons skilled in the art would understand these embodiments may be applicable to other networks such as LTE, “eLTE” proposed by 3GPP Release 15 and the like, or even applicable to coexistence of eLTE and NR.

FIG. 6schematically depicts an exemplary network700in which some embodiments of the present disclosure can be implemented.

According to one embodiment, the network700may be 5G wireless communication network which mainly comprises a core network being referred to as Next Generation Core, and one or more access point being referred to as NR base station (NR BS) or NR NodeB (gNB).

According to another embodiment, the network700may be based on combination of two or more of 3G, 4G, 4.5G and 5G network (“XG” refers to Xthgeneration). In addition to the NR BS or the NR gNB, the network700may further comprise other types of wireless access points, for example, radio base station for 3G, NodeB (NB) for LTE, or enhanced NodeB (eNB) for eLTE. As an example, the gNB(s) for NR and the eNB(s) for eLTE may coexist and share the same core network, e.g. as shown inFIG. 6, in the earlier deployment stage during evolution from LTE to 5G. It should be noted that the connection from the eNB to the core network and the coverage of the eNB are shown by dotted lines inFIG. 6, which implies that the eNB(s) may be replaced with the gNB(s) in the future 5G network.

Evolving to 5G includes work on a New Radio (NR) Access Technology (RAT). A general description of the agreements on 5G New Radio (NR) Access Technology so far is contained in 3GPP TR 38.802 V14.0.0 (2017-03). The NR needs to support multiple types of services, such as enhanced Mobile Broadband (eMBB), massive Machine Type Communications (mMTC) and Ultra-Reliable and Low Latency Communications (URLLC). For eMBB service being characterized by higher spectral efficiency and higher user experience throughput, its quality of service (QoS) requirement is medium and usually a Block Error Rate (BLER) of 10% is good enough for initial transmission, and Radio Link Control (RLC) automatic repeat request (ARQ) or sometimes Packet Data Compression Protocol (PDCP) retransmission can be used to resolve residual Medium Access Control (MAC) transmission error. However, URLLC service requires instant network access with low latency and high reliability for use in mission critical communication. Thus, URLLC has very strict requirement on delay and reliability, with a target BLER of less than 1%, and RLC/PDCP retransmission is not allowed due to the tight delay budget. The mMTC service requires very high density of device deployment where each device may be generating intermittent short burst of data traffic.

The NR may support a mixed traffic environment where two or more traffic for different services are provided concurrently from a network node to a user equipment (UE). For example, the first traffic from eMBB service and the second traffic from URLLC service may be multiplexed on the same radio channel by dynamic resource sharing. It is to be noted that the term “concurrently” means the two or more traffic may be simultaneously transmitted in at least part of transmission duration, but not necessarily be the case in the whole of the transmission duration. It is possible the first traffic may be transmitted all the time while the second traffic may be rather sparse.

The conventional link adaptation scheme used in the LTE cannot cope with such a mixed traffic environment, because the scheme typically may treat all traffic in the same way by one link adaptation loop, and cannot meet the different QoS requirements of different services. For example, if the target BLER is set high as for eMBB service, then the selected Modulation and Coding Scheme (MCS) may be too high for URLLC service and may result in too many transmission errors. If the target BLER is set low as for URLLC service, then the selected MCS may be too low for eMBB service and may result in low spectrum efficiency.

FIG. 1is a flow diagram for illustrating a method100for performing link adaptation at a network node in a wireless communication network, according to some embodiments of the present disclosure.

The method100may comprise: identifying first traffic and second traffic included in transmission between the network node and a user equipment (UE), wherein the first traffic is related to first service having a first quality of service (QoS) requirement, and the second traffic is related to second service having a second QoS requirement, at step101; and applying a first link adaptation loop catering for the first QoS requirement to the first traffic at step102, and applying a second link adaptation loop catering for the second QoS requirement to the second traffic at step103.

Said QoS requirement may comprise a target Block Error Rate (BLER), allowable maximum delay, and/or other parameters related to service quality.

In an exemplary embodiment, the first service is eMBB service having target BLER of lower than 10%, and the second service is URLLC service having target BLER of lower than 1%. The method of the present disclosure enables two link adaptation loops to be used separately for eMBB and URLLC services, so that the different target BLER requirements for eMBB and URLLC services can be satisfied concurrently.

It is to be noted that although the method100is discussed in the context of two services, persons skilled in the art would understand that the inventive concept of this disclosure may be applicable to a situation having more than two services.

In one exemplary embodiment, said identifying of traffic at the step101may be based on logical channel identifier (ID) included in each transport block for the respective traffic. For example, from the transport block itself, the network can know whether a transport block is used to transmit eMBB traffic or URLLC traffic by checking the logical channel ID included in the transport block, because the eMBB traffic and the URLLC traffic should be mapped to different logical channels.

In another exemplary embodiment, said identifying of traffic at the step101may be based on different length of transmission time interval (TTI) or numerology for the respective traffic. The term “numerology” refers to basic physical layer parameters, such as those parameters regarding subframe structure, and may include transmission bandwidth, frame duration, subframe duration, slot duration, symbol duration, subcarrier spacing, sampling frequency, number of subcarrier, resource blocks (RBs) per subframe, symbols per subframe, cyclic prefix (CP) length and so on. Numerology in the NR may be defined by subcarrier spacing and CP overhead. The NR can support flexible/scalable numerology. Multiple subcarrier spacings can be derived by scaling a basic subcarrier spacing by an integer. For example, the subcarrier spacing may be selected as 15 kHz, 30 kHz, 60 kHz or 120 kHz, wherein larger subcarrier spacing may be used for higher frequencies to obtain robustness to higher phase noise. The CP length may be selected as 4.7 μs, 2.4 μs, 1.2 μs or 0.6 μs, wherein larger CP length may be used for lower frequencies. The support of multiple numerologies has been agreed for NR, which numerologies can be multiplexed in the frequency and/or time domain for the same or different UEs. Different numerologies may thus coexist on the same subcarrier. Each gNB for the NR may transmit different traffic using different numerologies which are time division multiplexed (TDM) or frequency division multiplexed (FDM). Hence, traffic may be identified based on the numerology for the respective traffic.

In an exemplary embodiment, the step102and the step103may be performed simultaneously or alternatively in time domain, depending on occurrence or not of the first traffic or the second traffic in the transmission. For example, the first traffic may be constantly transmitted so that the step102may be performed at every TTI, while the second traffic may be rather sparse, so that the step103may be performed at intervals of e.g. ten TTIs.

FIG. 2is a flow diagram for illustrating a method200for performing link adaptation according to one embodiment of the present disclosure.

The method200may be performed at a network node in a wireless communication network, and may comprise: identifying first traffic and second traffic at step101; and applying a first link adaptation loop to the first traffic at step102, and applying a second link adaptation loop to the second traffic at step103, wherein the steps101,102and103of the method200may be similar as those steps of the method100as discussed above. According to the method200, the second link adaptation loop is independent from the first link adaptation loop.

In an exemplary embodiment, said step102of applying the first link adaptation loop may comprise: obtaining a first channel condition and a first transmission result regarding the first traffic, at step211; determining a first transport block size index (TBSI) based on the first channel condition, the first transmission result and the first QoS requirement, at step212; and selecting a first MCS based on the first TBSI, at step213. Moreover, said step103of applying the second link adaptation loop may comprise: obtaining a second channel condition and a second transmission result regarding the second traffic, at step221; determining a second TBSI based on the second channel condition, the second transmission result and the second QoS requirement, at step222; and selecting a second MCS based on the second TBSI, at step223.

For downlink transmission, said channel condition may comprise channel quality indicator (CQI) reported by the UE, and said transmission result may comprise Hybrid Automatic Repeat Request (HARQ) feedback from the UE, for example, acknowledgement (ACK) or non-acknowledgement (NACK). For uplink transmission, said channel condition may comprise signal to interference noise ratio (SINR) measured at the network node, and said transmission result may comprise decoding result at the network node. Other parameters for the channel condition or the transmission result may be also feasible for some methods in the present disclosure.

In one exemplary embodiment, for downlink transmission, the first or second TBSI may be determined (at step212or at step222) by mapping a respective CQI to a mapped TBSI, and adjusting the mapped TBSI based on a respective HARQ feedback and a respective target BLER. As a non-limiting example, an adjustment variable for adjusting the mapped TBSI may be decreased by a step TBSadjust_stepupon receipt of NACK and increased by TBSIadjust_step/(1/BLERtgt−1) upon receipt of ACK, wherein BLERtgtis the target BLER of the respective service.

Moreover, the adjusted TBSI should be limited within the scope of 0 to 26. The mapping between MCS Index and transport block size index (TBSI or TBS Index) is defined in 3rdGeneration Partnership Project Technical Specification (3GPP TS) 36.213, e.g. Table 7.1.7.1-1, which is incorporated herein by reference.

In an exemplary implementation, the network node shall also consider buffer status at network side for downlink adaptation, or buffer status at UE side for uplink adaptation, during determination of TBSI. For example, a smaller TBSI may be determined by comparison between the adjusted TBSI, and required TBSI for the buffer status at the network side or at the UE side, and then, the first MCS or the second MCS may be selected (at step213or at step223) based on the smaller TBSI.

In practice, the buffer status of the UE may be estimated by the network node based on a buffer status report received from the UE and data having been scheduled for transmission from the UE until receipt of the buffer status report.

As a non-limiting example, the first link adaptation loop may use the following equations:

TBSImapped=⌊2·(CQI-2)⌋,CQI>1TBSIadjusted⁢⁢_⁢⁢eMBB=min⁡(max⁡(⌊TBSImapped+TBSIadjusted⁢⁢_⁢⁢eMBB⌋,0),⁢26)whereTBSIadjusted⁢⁢_⁢⁢eMBB⁡(t+1)=TBSIadjusted⁢⁢_⁢⁢eMBB⁡(t)+((ACKeMBB==1)·11BLERtgt⁢⁢_⁢⁢eMBB-1-(NACKeMBB==1))·TBSIadjust⁢⁢_⁢⁢step⁢⁢_⁢⁢eMBB
and, the second link adaptation loop may uses the following equations:

TBSImapped=⌊2·(CQI-2)⌋,CQI>1TBSIadjusted⁢⁢_⁢⁢URLLC=min⁡(max⁡(⌊TBSImapped+TBSIadjusted⁢⁢_⁢⁢URLLC⌋,0),⁢26)whereTBSIadjusted⁢⁢_⁢⁢URLLC⁡(t+1)=TBSIadjusted⁢⁢_⁢⁢URLLC⁡(t)+((ACKURLLC==1)·11BLERtgt⁢⁢_⁢⁢URLLC-1-(NACKURLLC==1))·TBSIadjust⁢⁢_⁢⁢step⁢⁢_⁢⁢URLLC
wherein:
TBSImappedis the first or second mapped TBSI determined based on the first or second CQI;
TBSIadjusted_eMBBand TBSIadjusted_URLLCare the first TBSI and the second TBSI finally determined by adjusting the first mapped TBSI and the second mapped TBSI, respectively;
TBSIadjust_eMBBand TBSIadjust_URLLCare adjustment variables for the first mapped TBSI and the second mapped TBSI, respectively,
wherein:
TBSIadjust_eMBBis decreased by a step TBSIadjust_step_eMBBupon receipt of NACK and increased by TBSIadjust_step_eMBB/(1/BLERtgt_eMBB−1) upon receipt of ACK, wherein BLERtgt_eMBBis the target BLER of the eMBB service; and
TBSIadjust_URLLCis decreased by a step TBSIadjust_step_URLLCupon receipt of NACK, and increased by TBSIadjust_step_URLLC/(1/BLERtgt_URLLC−1) upon receipt of ACK, wherein BLERtgt_URLLCis the target BLER of the URLLC service.

In another exemplary embodiment, for downlink transmission, the determination of the first or second TBSI may comprise: calculating a SINR based on a respective CQI; and determining an effective SINR by summing the calculated SINR and an adaptive offset; and determining a respective TBSI based on the effective SINR, wherein the adaptive offset is decreased by a first step in response to HARQ NACK, and increased by a second step in response to HARQ ACK, the first step and second step are selected based on respective target BLER.

In still another exemplary embodiment, for uplink transmission, the determination of the first or second TBSI may comprise: predicting a maximum achievable SINR by summing the SINR measured at the network node and a SINR adjustment variable; determining the TBSI based on the maximum achievable SINR, wherein the SINR adjustment variable is decreased by a step SINRadjust_stepin response to decoding failure, and increased by SINRadjust_step/(1/BLERtgt−1) in response to decoding success, said BLERtgtis target block error rate (BLER) which is different for the first service having the first QoS requirement and the second service having the second QoS requirement.

In an exemplary embodiment, said obtaining of the transmission result may comprise distinguishing whether the HARQ feedback or the decoding result corresponds to the first service or the second service. As a non-limiting example, said distinguishing of the decoding result may be based on a logical channel identifier (ID) included in each transport block. Said distinguishing of the HARQ feedback may be based on a logical channel ID included in each transport block, and correspondence between each downlink transport block and its respective HARQ feedback. Said correspondence may be a Downlink Assignment Index (DAI) and a HARQ feedback bitmap when a common HARQ feedback channel is used.

The method of the present disclosure may further comprise configuring parameters for the first and second link adaptation loops via Operations, Administration and Maintenance (OAM) interfaces.

FIG. 3is a flow diagram for illustrating a method300for performing link adaptation according to another embodiment of the present disclosure.

The method300may comprise: identifying first traffic and second traffic at step101; and applying a first link adaptation loop to the first traffic at step102, and applying a second link adaptation loop to the second traffic at step103a, wherein the steps101,102and103aof the method300may be similar as those steps of the method100as discussed above. According to the method300, the second link adaptation loop may be configured to be dependent on the first link adaptation loop.

In an exemplary embodiment, said step102of applying the first link adaptation loop may comprise: obtaining a first channel condition and a first transmission result regarding the first traffic, at step211; determining a first TBSI based on the first channel condition, the first transmission result and the first QoS requirement, at step212; and selecting a first MCS based on the first TBSI, at step213. In contrast to the step103of the method200, said step103aof applying the second link adaptation loop may comprise: deriving a second channel condition and a second transmission result regarding the second traffic from the first channel condition and the first transmission result, respectively, at step221a; determining a second TBSI based on the second channel condition, the second transmission result and the second QoS requirement, at step222a; and selecting a second MCS based on the second TBSI, at step223a.

In an exemplary embodiment, a radio channel is shared by the first traffic and the second traffic. For example, the first traffic from eMBB service and the second traffic from URLLC service may be multiplexed on the same radio channel, so that the first traffic and second traffic may suffer from almost the same channel condition (e.g. fading and/or interference). Thus, the deriving of the second channel condition may comprise directly taking the first channel condition as said second channel condition.

In an exemplary embodiment, the deriving of the second transmission result may comprise proportionally converting the first transmission result into a hypothetical result as said second transmission result, according to ratio between the first QoS requirement and the second QoS requirement.

One potential issue with the above method200ofFIG. 2is that, as the target BLER for URLLC service is quite low, it will take quite long convergence time for the link adaptation loop for URLLC service. Sometimes, the method200may be not feasible if the URLLC traffic is much sparser than the eMBB traffic, because channel condition (e.g. fading and/or interference) may have already changed between two neighboring URLLC data block transmission, so that using the decoding result of previous transmission having occurred very early to adjust the TBSI of a current transmission may not be suitable. However, it is possible the eMBB traffic is constantly or frequently transmitted, the link adaptation loop for eMBB service has a short convergence time. When the radio channel is shared by eMBB and URLLC services, the channel condition may be almost the same for these two services. Hence, the channel condition for eMBB traffic may be regarded as the channel condition for URLLC traffic. Moreover, although the decoding result of eMBB traffic should not be used directly to adjust URLLC link adaptation loop, the decoding result of eMBB traffic can provide useful information about what the decoding result for URLLC traffic would look like.

Using the method300ofFIG. 3, the channel condition and the transmission result regarding the URLLC traffic may be derived from the channel condition and the transmission result of the eMBB traffic. It is beneficial to run URLLC link adaptation loop based on eMBB link adaptation loop for the reasons discussed above. The method300is particularly advantageous in some circumstances, for example when the traffic pattern for URLLC is much sparser as compared with that of eMBB.

Moreover, using the method300ofFIG. 3, the link adaptation loop of URLLC may be updated even when there is no URLLC traffic transmission but there is traffic transmission (either uplink or downlink) for eMBB. The difference between two loops is that, for each correct eMBB data transmission, eMBB link adaptation loop will increase its TBSI. As to URLLC link adaptation loop, its TBSI will be increased only when consecutive ‘n’ eMBB data blocks are received correctly. If any one of the n eMBB data blocks is NACKed, the TBSI is decreased. The parameter ‘n’ is related to the target BLER comparison between the URLLC service and the eMBB service. For instance, if the target BLER of URLLC is 1% and that of eMBB is 10%, then ‘n’ can be set as 10. That is, a hypothetical link adaptation for URLLC may be running in the absence of URLLC traffic if traffic transmission is ongoing for eMBB. That hypothetical outer loop may mimic what could happen for URLLC traffic according to the transmission results of eMBB traffic.

FIG. 4is a flow diagram for illustrating a method400for performing link adaptation according to still another embodiment of the present disclosure.

The method400may comprise: identifying first traffic and second traffic at step101; and applying a first link adaptation loop to the first traffic at step102, and applying a second link adaptation loop to the second traffic at step103b, wherein the steps101,102and103bof the method400may be similar as those steps of the method100as discussed above. According to the method400, the second link adaptation loop may be configured to be dependent on the first link adaptation loop.

In an exemplary embodiment, said step102of applying the first link adaptation loop may comprise: obtaining a first channel condition and a first transmission result regarding the first traffic, at step211; determining a first TBSI based on the first channel condition, the first transmission result and the first QoS requirement, at step212; and selecting a first MCS based on the first TBSI, at step213. In contrast to the step103aof the method300, said step103bof applying the second link adaptation loop may comprise: determining a second TBSI by subtracting m from the first TBSI, at step222b; and selecting a second MCS based on the second TBSI, at step223b, wherein m is a positive integer obtained by estimation, measurement or simulation for the first and second services.

For example, in a simplified solution, the TBSI for URLLC traffic may be always set as the TBSI for eMBB traffic minus “m”.

FIG. 5is a block diagram for schematically illustrating a network node500according to some embodiments of the present disclosure.

The network node500may be one of: a radio base station, a node B (NB), an enhanced Node B (eNB), a New Radio (NR) base station (NR BS) or NR NodeB (gNB), and other wireless access point in a wireless communication network. In an exemplary embodiment, the wireless communication network may use a New Radio (NR) access technology. For example, the wireless communication network may be network700as shown inFIG. 6.

In one exemplary embodiment, the network node500in a wireless communication network may be configured for performing link adaptation for traffic included in transmission between the network node and a user equipment (UE). For example, any embodiment of the methods in the present disclosure can be implemented by the network node500. The network node500may comprise a communication interface501and a processing circuitry. Said processing circuitry may be configured to enable the network node500to: identify first traffic and second traffic included in the transmission between the network node and the UE, wherein the first traffic is related to first service having a first QoS requirement, and the second traffic is related to second service having a second QoS requirement; and apply a first link adaptation loop catering for the first QoS requirement to the first traffic, and apply a second link adaptation loop catering for the second QoS requirement to the second traffic.

Said processing circuitry may be implemented by hardware component(s) and/or integrated circuit(s). Alternatively, said processing circuitry may comprise a memory and a processor, wherein the memory is configured to store computer program code being executable by the processor.

In another exemplary embodiment, the network node500may comprise a communication interface501configured to perform communication with a UE600, a processor502, and a memory503. The memory503may contain instructions that when executed may cause the processor502to perform any embodiment of the methods in the present disclosure.

As a non-limiting example, said processor502may refer to a central processing unit (CPU), a microprocessor, a multi-core processor, a general-purpose processor, a dedicated-purpose processor or the like. Said memory503may refer to any machine readable storage medium (also called computer readable storage medium), such as magnetic disks, optical disks, read only memory (ROM), random access memory (RAM), flash memory devices, non-volatile memory, volatile memory or the like.

The term “UE” used herein may refer to any object enabled to communicate via a communication network, for example, a mobile telephone, a laptop with communication interface, personal digital assistants (PDA), computing device, vehicles having communication interface, or other devices such as meters, household appliances, medical appliances, multimedia devices and so on.

According to an exemplary embodiment, there is provided a computer program comprising computer program code which, when executed in a network node, causes the network node to perform any method as discussed in the present disclosure. As a non-limiting example, said computer program may be contained in a carrier, wherein the carrier is one of an electronic signal, optical signal, radio signal, and computer readable storage medium.

According to an exemplary embodiment, there is provided an apparatus for performing link adaptation in a wireless communication network. The apparatus may comprise function modules for performing each step in any embodiment of the methods of the present disclosure. Said function modules may be implemented by software, hardware, firmware, or any combination of them.

The embodiments in the present disclosure are not described with reference to any particular programming language. It will be appreciated that a variety of programming languages may be used to implement the teachings of the embodiments as described herein.

It is to be noted that, some embodiments have been presented in a form of flow diagram or block diagram. It will be appreciated that the orders of the steps and blocks as shown in these diagrams are only intended for illustrative purpose rather than for limitation of the present invention. Persons skilled in the art would recognize that some variations can be made to these diagrams without departing from the broader spirit and scope as claimed in the appended claims.

Throughout the description, the embodiments of the present disclosure have been described with reference to some specific details. It will be evident that various modifications may be made thereto without departing from the broader spirit and scope as claimed in the appended claims. Accordingly, the description and the drawings shall be interpreted in an illustrative sense rather than a restrictive sense.