The proposed technology presented herein relates to a method, a network node, a computer program for handling link adaptation in a wireless communications network.
In a typical wireless communication network, wireless devices, also known as wireless communication devices, mobile stations, stations (STA) and/or User Equipments (UE), communicate via a Wide Area Network or a Local Area Network such as a Wi-Fi network or a cellular network comprising a Radio Access Network (RAN) part and a Core Network (CN) part. The RAN covers a geographical area which is divided into service areas or cell areas, which may also be referred to as a beam or a beam group, with each service area or cell area being served by a radio network node such as a radio access node e.g., a Wi-Fi access point or a radio base station (RBS), which in some networks may also be denoted, for example, a NodeB, eNodeB (eNB), or gNB as denoted in Fifth Generation (5G) telecommunications. A service area or cell area is a geographical area where radio coverage is provided by the radio network node. The radio network node communicates over an air interface operating on radio frequencies with the wireless device within range of the radio network node.
3GPP is the standardization body for specify the standards for the cellular system evolution, e.g., including 3G, 4G, 5G and the future evolutions. Specifications for the Evolved Packet System (EPS), also called a Fourth Generation (4G) network, have been completed within the 3rd Generation Partnership Project (3GPP). As a continued network evolution, the new releases of 3GPP specifies a 5G network also referred to as 5G New Radio (NR).
Frequency bands for 5G NR are being separated into two different frequency ranges, Frequency Range 1 (FR1) and Frequency Range 2 (FR2). FR1 comprises sub-6 GHz frequency bands. Some of these bands are bands traditionally used by legacy standards but have been extended to cover potential new spectrum offerings from 410 MHz to 7125 MHz. FR2 comprises frequency bands from 24.25 GHz to 52.6 GHz. Bands in this millimeter wave range have shorter range but higher available bandwidth than bands in the FR1.
Multi-antenna techniques may significantly increase the data rates and reliability of a wireless communication system. For a wireless connection between a single user, such as UE, and a base station, the performance is in particular improved if both the transmitter and the receiver are equipped with multiple antennas, which results in a Multiple-Input Multiple-Output (MIMO) communication channel. This may be referred to as Single-User (SU)-MIMO. In the scenario where MIMO techniques is used for the wireless connection between multiple users and the base station, MIMO enables the users to communicate with the base station simultaneously using the same time-frequency resources by spatially separating the users, which increases further the cell capacity. This may be referred to as Multi-User (MU)-MIMO. Note that MU-MIMO may benefit when each UE only has one antenna. Such systems and/or related techniques are commonly referred to as MIMO.
Link adaptation (LA) algorithms are designed to meet an average Block Error Rate (BLER) target. LA algorithms in a base station, exploit a control loop to adjust a Signal-to-interference-plus-noise ratio (SINR) estimate recovered from a Channel Quality Indicator (CQI), and hence a Modulation and Coding Scheme (MCS), so as to meet a long-term BLER target.
Link adaptation for Physical Downlink Shared Channel (PDSCH) and Physical Uplink Shared Channel (PUSCH) comprises:
For PDSCH, Channel State Information (CSI) reported by UE, CQI and/or Rank Indicator (RI), is commonly used as channel quality input for LA.
For PUSCH, received SINR is measured in the base station and used as channel quality input for LA.
An overview of how this is performed is illustrated in
Below examples is for Downlink (DL), but the idea applies to Uplink (UL) as well.
Very Simplified Link Adaptation Function
Information Carrying Capacity (ICC) when used herein may refer to how many data bits that each resource element is carrying. A higher value indicates a higher code-rate and/or higher modulation. A lower value indicates the opposite.
Outer Loop Adjustment (OLA) when used herein means an adjustment of an ICC estimate, which in turn affects the SI NR value. The adjustment is performed based on HARQ feedback to meet a target block error rate.
There currently exist certain challenges.
As part of developing embodiments herein a problem is identified and first discussed.
From field and laboratory tests a higher NACK ratio has been observed in a certain slot, MCS, rank or combination of those. A NACK ratio when used herein means number of HARQ NACK reported by UE/(HARQ ACK+HARQ NACK). A rank when used herein means a rank used by a network for the given transmission.
This may be caused by different reasons, where some are stated below:
As a consequence, certain combination of rank, MCS and slot NACK ratio may be high.
Certain aspects of the present disclosure and their embodiments may provide solutions to these or other challenges
An object of embodiments herein is to provide an improved throughput in a wireless communications network, in particular by providing a method for more efficiently and accurately handling link adaptation.
According to a first aspect of embodiments herein, the object is achieved by a method performed by a network node for handling link adaptation for a communication between the network node and a User Equipment, UE, in a wireless communications network.
The method comprises:
According to second aspect of the embodiments herein, the object is achieved by a network node configured to handle link adaptation for a communication between the network node and a User Equipment, UE in a wireless communications network. The network node is further being configured to:
An advantage of embodiments herein is that a more accurate LA is provided since the BLER target is achieved more accurate, resulting in an improved throughput.
The embodiments, together with further objects and advantages thereof, may best be understood by making reference to the following description taken together with the accompanying drawings, in which:
Embodiments herein provide methods performed by a network node for handling link adaptation for a communication between the network node and a User Equipment, UE, in a wireless communications network.
Network nodes such as a network node 110 operate in the wireless communications network 100, by means of antenna beams, referred to as beams herein. The network node 110 e.g. provides a number of cells referred to as cell1 and cell2, and may use these cells for communicating with e.g. a UE 120. The network node 110 may be a transmission and reception point e.g. a radio access network node such as a base station, e.g. a radio base station such as a NodeB, an evolved Node B (eNB, eNode B), an NR Node B (gNB), a base transceiver station, a radio remote unit, an Access Point Base Station, a base station router, a transmission arrangement of a radio base station, a stand-alone access point, a Wireless Local Area Network (WLAN) access point, an Access Point Station (AP STA), an access controller, a UE acting as an access point or a peer in a Device to Device (D2D) communication, or any other network unit capable of communicating with a UE within any of cell1 and cell2 served by the network node 110 depending e.g. on the radio access technology and terminology used.
User Equipments operate in the wireless communications network 100, such as a UE 120. The UE 120 may e.g. be an NR device, a mobile station, a wireless terminal, an NB-IoT device, an eMTC device, an NR RedCap device, a CAT-M device, a WiFi device, an LTE device and an a non-access point (non-AP) STA, a STA, that communicates via a base station such as e.g. the network node 110, one or more Access Networks (AN), e.g. RAN, to one or more core networks (CN). It should be understood by the skilled in the art that the UE relates to a non-limiting term which means any UE, terminal, wireless communication terminal, user equipment, (D2D) terminal, or node e.g. smart phone, laptop, mobile phone, sensor, relay, mobile tablets or even a small base station communicating within a cell.
CN nodes such as a CN node 130 operates in the wireless communications network 100. The CN node may e.g. be an AMF node or an SMF node.
See the below example, e.g. relating to BLER heat map based MCS backoff according to embodiments herein, wherein the new functions are marked as underlined, and wherein the input parameters are marked as underlined and bold.
A BLER heat map when used herein means a matrix of measured BLER values connected to slot, rank and MCS. MCS back off when used herein means the adjustment applied to the link adaptation based on the value in the BLER heatmap. A slot when used herein refers to time interval which transmission take place (3gpp 38.211 Table 4.3.2-1)
The network node 110 may, at each received DL HARQ Feedback (e.g. in initial Tx only) perform the following:
1. Populate and update any one or more out of three 3-dimensional tables: Count Table, BLER Table and/or ICC offset Table.
Reset the above tables after certain number of subframes (MAX SF Count) to avoid acting on old data and data overflow.
The network node 110 may, at each DL transmission, i.e. at each slot, perform:
Run a legacy Link adaptation to choose the rank and initial mcs. This is input for icc_offset.
Lookup icc_offset“[mcs, rank, slot]” to get icc_offset for this slot. This is to select new MCS based on count table and BLER table, as explained in above.
Schedule the UE 120 with the adjusted mcs.
According to embodiments herein an example method may be provided to measure BLER per rank, MCS and slot at each HARQ feedback on initial transmission, as shown in the BLER heat map of
For example, if the BLER heatmap shows that a certain ICC X has a high BLER for a certain rank Y vs a certain slot Z and if legacy LA chose that ICC X for slot Z vs rank Y then delta ICC will be applied to reduce the ICC.
Methods herein may in one aspect be performed by the network node 110. As an alternative, a Distributed Node (DN) and functionality, e.g. comprised in a cloud 140 as shown in
The method comprises the actions below which is shown in the flowchart of
Action 601
The network node 110 obtains an initial ICC estimate.
Initially of this method, network node 110 obtains an ICC estimate, this is referred to as an initial ICC estimate. Later on, it will be determined whether or not this initial ICC estimate shall be adjusted. In other words, the initial ICC estimate is an uncompensated ICC estimate that later on, may or may not be compensated according to embodiments herein.
The initial ICC estimate may e.g. be used to estimate an initial MCS. The initial ICC estimate when used herein may mean information carrying capacity based on channel quality measurements.
Action 602
The network node 110 establishes a measurement at each HARQ feedback on an initial transmission in the communication. The measurement comprises a BLER per: Rank, MCS and slot.
To establish the BLER per rank, MCS and slot measurements, also referred to as the BLER heat map, gives the possibility to compensate when the BLER deviates significantly from the target.
In some embodiments, the network node 110 establishes a measurement, that further comprises: Counting per: rank, MCS; and slot, ACKs, and/or NACKs, received in HARQ feedbacks during the initial transmission in the communication. This is e.g. to realize the measurement of the BLER, it may also serve as way to assess the amount of ACKs and NACKs that have been used in the BLER calculation.
Action 603
Based on the established measurement, the network node 110 determines whether or not to adjust the initial ICC estimate, and disable outer loop ICC adjustments.
In some embodiments, this means that the network node 110 determines whether or not to adjust the initial ICC estimate.
In some further embodiments, this e.g. means that the network node 110 determines whether or not to disable outer loop ICC adjustments. This means that the ICC estimate may not be adjusted based on HARQ ACK or HARQ NACK receptions.
In some yet further embodiments, this e.g. means that the network node 110 determines whether or not to adjust the initial ICC estimate, and whether or not to disable outer loop ICC adjustments.
In some of these embodiments, the determining is to be used as a basis for the link adaptation of said communication. This will be explained more in detail below.
In some embodiments the network node determines whether or not to adjust the initial ICC estimate and/or disable outer loop ICC adjustments based on the number of ACKs and/or NACKs counted in the HARQ feedback.
In some embodiments, the network node 110 determines to adjust the initial ICC estimate and/or disable outer loop ICC adjustments when any one or more out of:
In some embodiments, the network node 110 determines to not adjust the initial ICC estimate and/or not disable outer loop ICC adjustments when any one or more out of:
Action 604
In some embodiments, when it has been determined to adjust the initial ICC estimate, the network node 110 may determine how much to adjust the initial ICC estimate, based on the established measurement. This may e.g. be performed by applying a fixed value for the ICC adjustment or proportional to the difference between the measured BLER and the BLER target.
The method will now be further explained and exemplified in below embodiments. These below embodiments may be combined with any suitable embodiment as described above.
The below example embodiments relate to a Link adaptation flow according to embodiments herein. The new functionality is marked as underlined.
Prior to each DL transmission the network node 110 may perform the following:
1. Receive a CQI report comprising a CQI estimate, e.g. from the UE 120.
2. The CQI estimate is translated to an ICC estimate, also referred to as the initial ICC estimate.
3. Possibly adjust the initial ICC estimate according to ACK/NACK feedback loop (input from step 10 below).
The Steps 1, 2 and/or 3 are performed to obtain the initial ICC estimate, mentioned in Action 601.
4. Determine the MCS based on the initial ICC estimate (possibly adjusted).
5. Adjust ICC according to the outcome of the new ICC adjustment algorithm (input from step 9 below) This is related to Action 603 and 604 described above.
6. Determine the MCS based on the final adjusted ICC. This is related to legacy link adaptation.
7. Calculate TBS (transport block size) based on legacy link adaptation (where MCS is one of many input parameters).
8. Transmit data using the calculated TBS
At each received DL HARQ Feedback (at initial Tx), the network node 110 may perform the following:
9. Calculate BLER table (NACK ratio per rank, mcs, slot) and count table (ACK+NACK count per rank, mcs, slot) This relates to Action 602 described above.
10. Re-calculate Outer loop adjustment depending on the outcome of Action 603 described above.
The ICC adjustment algorithm according to some example embodiments herein:
At each received DL HARQ FB (in initial Tx) the network node 110 may update any one or more out of the following three 3-dimensional tables: The three tables comprise the Count Table, the BLER Table and/or the ICC offset Table. as follows:
1. —The BLER table [#rank, #mcs, #slot]: e.g. comprising NACK ratio per MCS vs rank vs slot. This means updating the BLER table based on the updated count tables.
This relates to Action 602, wherein, at each HARQ feedback on an initial transmission in the communication, the network node 110 establishes a measurement, which measurement comprises a BLER per: rank, Modulation and Coding Scheme, MCS, and slot.
2. The count_table table [#rank, #mcs, #slot]: containing count of HARQ per mcs vs rank vs slot. This means updating the ACK and NACK count tables for relevant mcs, rank and slot.
3. The ICC offset Table comprises icc_offset calculated from the two tables above. This means that if the BLER table indicate BLER above a certain threshold, e.g. also referred to as the first threshold, and NACK and/or ACK count is above a second threshold then icc_offset is updated.
The network node 110 may reset the above tables after a certain number of DL feedback (MAX_SF_Count) also referred to as an SF Count threshold. SF means subframes which is an amount of time. This is to avoid acting on old data and to avoid data overflow.
High_Bler, High_Count_Ratio, MAX_SF_Count are tunable input parameters also referred to as thresholds.
Functions like BLER [#rank, #mcs, #slot] and count_table [#rank, #mcs, #slot] may also be utilized to adjust outer loop ICC (SINR). As mentioned above in action 603, network node 110 may determine whether or not to disable outer loop ICC adjustments.
If certain MCS vs slot vs rank has high BLER it could be good to skip NACK adjustment for that mcs vs slot vs rank.
The wording “MCS vs slot vs rank” when used herein e.g. means “a function of these three attributes”.
Outer Loop Adjustment (OLA)_adj [#rank, #mcs, #slot] meaning that the legacy Outer-Loop Adjustment will according to some embodiments herein be conditioned by action 603 which decides if the adjustment value should be updated at HARQ ACK/NACK reception. It may comprise:
This means that action 603 which decides if the adjustment value should be updated at HARQ ACK/NACK reception
At each DL transmission, i.e. step 5 in the new LA algorithm, the network node 110 may perform:
ΔICC may be a fixed parameter or a value dependent on MCS and derived from simulations or field data to reflect unilinear nature of ICC over MCS
Lookup icc_offset [mcs, rank, slot] to get icc_offset per ri, mcs, and slot and adjust the icc estimate. This means that if the BLER table indicates that the BLER is above certain threshold, e.g. first threshold, and NACK and/or ACK count is above a second threshold, then icc_offset is updated.
It may be costly memory utilization if the bier [#rank, #mcs, #slot] and count ratio [#rank, #mcs, #slot] are stored per UE. In that case the icc_offset functionality may preferably be applied for UEs such as the UE 120, that has high data in the buffer.
The network node 110 may comprise an input and output interface configured to communicate with each other. The input and output interface may comprise a wireless receiver (not shown) and a wireless transmitter (not shown).
The network node 110 may comprise an obtaining unit, a determining unit, and an establishing unit to perform the method actions as described herein.
The embodiments herein may be implemented through a respective processor or one or more processors, such as the processor of a processing circuitry in the network node 110 depicted in
The network node 110 may further comprise respective a memory comprising one or more memory units. The memory comprises instructions executable by the processor in the network node 110.
The memory is arranged to be used to store instructions, data, configurations, and applications to perform the methods herein when being executed in the network node 110.
In some embodiments, a computer program comprises instructions, which when executed by the at least one processor, cause the at least one processor of the network node 110 to perform the actions above.
In some embodiments, a respective carrier comprises the respective computer program, wherein the carrier is one of an electronic signal, an optical signal, an electromagnetic signal, a magnetic signal, an electric signal, a radio signal, a microwave signal, or a computer-readable storage medium.
Those skilled in the art will also appreciate that the functional modules in the network node 110, described below may refer to a combination of analog and digital circuits, and/or one or more processors configured with software and/or firmware, e.g. stored in the network node 110, that when executed by the respective one or more processors such as the processors described above cause the respective at least one processor to perform actions according to any of the actions above. One or more of these processors, as well as the other digital hardware, may be included in a single Application-Specific Integrated Circuitry (ASIC), or several processors and various digital hardware may be distributed among several separate components, whether individually packaged or assembled into a system-on-a-chip (SoC).
When using the word “comprise” or “comprising” it shall be interpreted as non-limiting, i.e. meaning “consist at least of”.
The embodiments herein are not limited to the above described preferred embodiments. Various alternatives, modifications and equivalents may be used.
Below, some example embodiments 1-12 are shortly described. See e.g.
Embodiment 1. A method performed by a network node 110 e.g. for handling link adaptation for a communication between the network node 110 and a User Equipment, UE, 120 in a wireless communications network 100, the method comprising any one or more out of:
Embodiment 2. The method according to embodiment 1, wherein establishing 602 a measurement, further comprises:
Embodiment 3. The method according to any of the embodiments 1-2, comprising:
Embodiment 4. The method according to any of the embodiments 1-3, wherein the determining of whether or not to adjust the initial ICC estimate and/or disable outer loop ICC adjustments, comprises:
Embodiment 5. The method according to any of the embodiments 1-4, wherein the determining of whether or not to adjust the initial ICC estimate and/or disable outer loop ICC adjustments, comprises:
Embodiment 6. A computer program comprising instructions, which when executed by a processor, causes the processor to perform actions according to any of the embodiments 1-5.
Embodiment 7. A carrier comprising the computer program of embodiment 6, wherein the carrier is one of an electronic signal, an optical signal, an electromagnetic signal, a magnetic signal, an electric signal, a radio signal, a microwave signal, or a computer-readable storage medium.
Embodiment 8. A network node 110 e.g. configured to handle link adaptation fora communication between the network node 110 and a User Equipment, UE, 120 in a wireless communications network 100, the network node further being configured to any one or more out of:
Embodiment 9. The network node 110 according to embodiment 8 further configured to establish, e.g. by means of the establishing unit, the measurement by:
Embodiment 10. The network node 110 according to any of the embodiments 8-9, further being configured to:
Embodiment 11. The network node 110 according to any of the embodiments 8-further configured to determine, e.g. by means of the determining unit, whether or not to adjust the initial ICC estimate and/or disable outer loop ICC adjustments by:
Embodiment 12. The network node 110 according to any of the embodiments 8-11, further configured to determine, e.g. by means of the determining unit, whether or not to adjust the initial ICC estimate and/or disable outer loop ICC adjustments by:
With reference to
The telecommunication network 3210 is itself connected to a host computer 3230, which may be embodied in the hardware and/or software of a standalone server, a cloud-implemented server, a distributed server or as processing resources in a server farm. The host computer 3230 may be under the ownership or control of a service provider, or may be operated by the service provider or on behalf of the service provider. The connections 3221, 3222 between the telecommunication network 3210 and the host computer 3230 may extend directly from the core network 3214 to the host computer 3230 or may go via an optional intermediate network 3220. The intermediate network 3220 may be one of, or a combination of more than one of, a public, private or hosted network; the intermediate network 3220, if any, may be a backbone network or the Internet; in particular, the intermediate network 3220 may comprise two or more sub-networks (not shown).
The communication system of
Example implementations, in accordance with an embodiment, of the UE, base station and host computer discussed in the preceding paragraphs will now be described with reference to
The communication system 3300 further includes a base station 3320 provided in a telecommunication system and comprising hardware 3325 enabling it to communicate with the host computer 3310 and with the UE 3330. The hardware 3325 may include a communication interface 3326 for setting up and maintaining a wired or wireless connection with an interface of a different communication device of the communication system 3300, as well as a radio interface 3327 for setting up and maintaining at least a wireless connection 3370 with a UE 3330 located in a coverage area (not shown) served by the base station 3320. The communication interface 3326 may be configured to facilitate a connection 3360 to the host computer 3310. The connection 3360 may be direct or it may pass through a core network (not shown in
The communication system 3300 further includes the UE 3330 already referred to. Its hardware 3335 may include a radio interface 3337 configured to set up and maintain a wireless connection 3370 with a base station serving a coverage area in which the UE 3330 is currently located. The hardware 3335 of the UE 3330 further includes processing circuitry 3338, which may comprise one or more programmable processors, application-specific integrated circuits, field programmable gate arrays or combinations of these (not shown) adapted to execute instructions. The UE 3330 further comprises software 3331, which is stored in or accessible by the UE 3330 and executable by the processing circuitry 3338. The software 3331 includes a client application 3332. The client application 3332 may be operable to provide a service to a human or non-human user via the UE 3330, with the support of the host computer 3310. In the host computer 3310, an executing host application 3312 may communicate with the executing client application 3332 via the OTT connection 3350 terminating at the UE 3330 and the host computer 3310. In providing the service to the user, the client application 3332 may receive request data from the host application 3312 and provide user data in response to the request data. The OTT connection 3350 may transfer both the request data and the user data. The client application 3332 may interact with the user to generate the user data that it provides. It is noted that the host computer 3310, base station 3320 and UE 3330 illustrated in
In
The wireless connection 3370 between the UE 3330 and the base station 3320 is in accordance with the teachings of the embodiments described throughout this disclosure. One or more of the various embodiments improve the performance of OTT services provided to the UE 3330 using the OTT connection 3350, in which the wireless connection 3370 forms the last segment. More precisely, the teachings of these embodiments may improve the applicable RAN effect: data rate, latency, power consumption, and thereby provide benefits such as corresponding effect on the OTT service: e.g. reduced user waiting time, relaxed restriction on file size, better responsiveness, extended battery lifetime.
A measurement procedure may be provided for the purpose of monitoring data rate, latency and other factors on which the one or more embodiments improve. There may further be an optional network functionality for reconfiguring the OTT connection 3350 between the host computer 3310 and UE 3330, in response to variations in the measurement results. The measurement procedure and/or the network functionality for reconfiguring the OTT connection 3350 may be implemented in the software 3311 of the host computer 3310 or in the software 3331 of the UE 3330, or both. In embodiments, sensors (not shown) may be deployed in or in association with communication devices through which the OTT connection 3350 passes; the sensors may participate in the measurement procedure by supplying values of the monitored quantities exemplified above, or supplying values of other physical quantities from which software 3311, 3331 may compute or estimate the monitored quantities. The reconfiguring of the OTT connection 3350 may include message format, retransmission settings, preferred routing etc.; the reconfiguring need not affect the base station 3320, and it may be unknown or imperceptible to the base station 3320. Such procedures and functionalities may be known and practiced in the art. In certain embodiments, measurements may involve proprietary UE signaling facilitating the host computer's 3310 measurements of throughput, propagation times, latency and the like. The measurements may be implemented in that the software 3311, 3331 causes messages to be transmitted, in particular empty or ‘dummy’ messages, using the OTT connection 3350 while it monitors propagation times, errors etc.
Filing Document | Filing Date | Country | Kind |
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PCT/SE2022/050243 | 3/11/2022 | WO |
Number | Date | Country | |
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63172302 | Apr 2021 | US |