Control channel quality reporting and link adaptation

Abstract

There is provided techniques for control channel link adaptation. A method is performed by a first radio transceiver device. The method comprises sending first control information over a control channel to a second radio transceiver device. A transmission setting is applied to the control channel whilst the first control information is sent. The method comprises receiving a report of received quality of the control channel from the second radio transceiver device. The method comprises sending second control information over the control channel to the second radio transceiver device. The transmission setting as applied to the control channel whilst the second control information is sent is updated at least partly based on the received report.

Description

[0001] CONTROL CHANNEL QUALITY REPORTING AND LINK ADAPTATION

[0002] TECHNICAL FIELD

[0003] Embodiments presented herein relate to a method, a first radio transceiver device, a computer program, and a computer program product for control channel link adaptation. Embodiments presented herein further relate to a method, a second radio transceiver device, a computer program, and a computer program product for control channel quality reporting.

[0004] BACKGROUND

[0005] In general terms, Downlink Control Information (DCI) can be used to schedule (i.e., to allocate physical resources for) downlink data (as e.g., sent on a physical downlink shared channel, PDSCH), uplink data (as e.g., sent on a physical uplink shared channel, PUSCH) and to provide information to adjust the uplink transmission power on both data channels (such as PUSCH) and control channels (such as on the physical uplink control channel, PUCCH). The DCI itself is transmitted on a downlink control channel (such as on the physical downlink control channel, PDCCH).

[0006] In further detail, the transmission of the DCI is protected by a cyclic redundancy check (CRC). In this respect, the CRC as transmitted over the air is affected by the identity of the targeted user equipment (or, more generally, the Radio Network Temporary Identifier, RNTI). Thus, when decoding the control information in the user equipment, information intended for another user equipment appears as noise to the receiver, resulting in a failed CRC check and the user equipment taking no further action.

[0007] The PDCCH is transmitted using 1, 2, 4, 8, or 16 contiguous control-channel elements (CCEs) with the number of control-channel elements used referred to as the aggregation level. The control-channel element is defined on the search spaces for blind decoding. A control-channel element consists of six resource-element groups (REGs), each of which is equal to one resource block (12 subcarriers) in one Orthogonal Frequency Division Multiplexing (OFDM) symbol. Demodulation reference signals (DM-RS) are also inserted in the PDCCH to support the channel estimation necessary at the user equipment in order to decode the content sent on the PDCCH. After accounting for the DM-RS overhead, there are 54 resource elements (corresponding to 108 bits) available for PDCCH transmission in one control-channel element.

[0008] The network may adapt the number of CCEs used when addressing a user equipment based on assumed channel quality. This is generally referred to as link adaptation. By using a larger aggregation level, more coded bits can be sent, and hence the reception probability of the PDCCH at the targeted user equipment increases.

[0009] To support link adaptation for the downlink data channel, the user equipment might report channel state information (CSI) back to the network. For this purpose, the user equipment is configured with resources for estimating the channel and resources for estimating interference. These resources are commonly provided in terms of a channel state information reference signal (CSI-RS). Based on estimates obtained by the user equipment from measurement on these resources, the user equipment may feedback one or more of the following: a channel quality indicator (CQI) value reflecting the quality of the wireless link to the network, a rank indicator (RI) indicating the rank of the wireless link as preferred by the user equipment, and a precoding matrix index (PMI) indicating an index in a pre-defined codebook, following the reported rank, where the indicated precoder give the best quality of all available precoders.

[0010] The above-disclosed CSI reporting yields good link adaptation to be possible for the downlink data channel. However, link adaptation for the downlink control channel might differ from the downlink data channel, for example due to difference in rank. For example, the PDCCH might have a fixed rank (such as rank 1 in New Radio based networks) whilst the PDSCH might be allowed to have an adaptive rank. Further, interference on the downlink control channel may also be significantly different from interference on the downlink data channel. This is since typically a dedicated set of symbols, separate from the downlink data channel symbols, are used for the downlink control channel. Most systems are time-aligned and use the same symbols for the downlink control channel, so the majority of the interference on the downlink control channel will come from downlink data channel transmissions in other cells. This is in contrast to interference on the downlink data channel which mostly come from downlink data channel transmissions in other cells. Hence, the reported CSI might not be accurate, or even applicable, to the downlink control channel.

[0011] W02013107053A1 relates to enhanced CSI reporting for downlink control channels, e.g. the enhanced Physical Downlink Control Channel (ePDCCH). In particular, the document relates to CSI signalling in the uplink (UL) in the case ePDCCH is used. One focus of the document is on providing an optimized support for ePDCCH link adaptation. WO2013107053A1 is an example of a document where measurements on a downlink data channel are transformed to performance for a downlink control channel.

[0012] In view of the above, there is therefore a need for more efficient (e.g., faster, more accurate) link adaptation for the downlink control channel.

[0013] SUMMARY

[0014] An object of embodiments herein is to address the above issues.

[0015] A particular object is to provide link adaptation for the downlink control channel such that the link adaptation does not suffer from the above issues, or where the above issues at least are mitigated or reduced.

[0016] A particular object is to provide both fast and accurate link adaptation for the downlink control channel. According to a first aspect there is presented a method for control channel link adaptation. The method is performed by a first radio transceiver device. The method comprises sending first control information over a control channel to a second radio transceiver device. A transmission setting is applied to the control channel whilst the first control information is sent. The method comprises receiving a report of received quality of the control channel from the second radio transceiver device. The method comprises sending second control information over the control channel to the second radio transceiver device. The transmission setting as applied to the control channel whilst the second control information is sent is updated at least partly based on the received report.

[0017] According to a second aspect there is presented a first radio transceiver device for control channel link adaptation. The first radio transceiver device comprises processing circuitry. The processing circuitry is configured to cause the first radio transceiver device to send first control information over a control channel to a second radio transceiver device. A transmission setting is applied to the control channel whilst the first control information is sent. The processing circuitry is configured to cause the first radio transceiver device to receive a report of received quality of the control channel from the second radio transceiver device. The processing circuitry is configured to cause the first radio transceiver device to send second control information over the control channel to the second radio transceiver device. The transmission setting as applied to the control channel whilst the second control information is sent is updated at least partly based on the received report.

[0018] According to a third aspect there is presented a first radio transceiver device for control channel link adaptation. The first radio transceiver device comprises a send module configured to send first control information over a control channel to a second radio transceiver device. A transmission setting is applied to the control channel whilst the first control information is sent. The first radio transceiver device comprises a receive module configured to receive a report of received quality of the control channel from the second radio transceiver device. The first radio transceiver device comprises a send module configured to send second control information over the control channel to the second radio transceiver device. The transmission setting as applied to the control channel whilst the second control information is sent is updated at least partly based on the received report.

[0019] According to a fourth aspect there is presented a computer program for control channel link adaptation. The computer program comprises computer code which, when run on processing circuitry of a first radio transceiver device, causes the first radio transceiver device to perform actions. One action comprises the first radio transceiver device to send first control information over a control channel to a second radio transceiver device. A transmission setting is applied to the control channel whilst the first control information is sent. One action comprises the first radio transceiver device to receive a report of received quality of the control channel from the second radio transceiver device. One action comprises the first radio transceiver device to send second control information over the control channel to the second radio transceiver device. The transmission setting as applied to the control channel whilst the second control information is sent is updated at least partly based on the received report.

[0020] According to a fifth aspect there is presented a method for control channel quality reporting. The method is performed by a second radio transceiver device. The method comprises receiving first control information over a control channel from a first radio transceiver device. The method comprises sending a report of received quality of the control channel to the first radio transceiver device when a trigger condition is fulfilled.

[0021] According to a sixth aspect there is a second radio transceiver device for control channel quality reporting. The second radio transceiver device comprises processing circuitry. The processing circuitry is configured to cause the second radio transceiver device to receive first control information over a control channel from a first radio transceiver device. The processing circuitry is configured to cause the second radio transceiver device to send a report of received quality of the control channel to the first radio transceiver device when a trigger condition is fulfilled.

[0022] According to a seventh aspect there is presented a second radio transceiver device for control channel quality reporting. The second radio transceiver device comprises a receive module configured to receive first control information over a control channel from a first radio transceiver device. The second radio transceiver device comprises a send module configured to send a report of received quality of the control channel to the first radio transceiver device when a trigger condition is fulfilled.

[0023] According to an eighth aspect there is presented a computer program for control channel quality reporting. The computer program comprises computer code which, when run on processing circuitry of a second radio transceiver device, causes the second radio transceiver device to perform actions. One action comprises the second radio transceiver device to receive first control information over a control channel from a first radio transceiver device. One action comprises the second radio transceiver device to send a report of received quality of the control channel to the first radio transceiver device when a trigger condition is fulfilled.

[0024] According to a ninth aspect there is presented a computer program product comprising a computer program according to at least one of the fourth aspect and the eighth aspect and a computer readable storage medium on which the computer program is stored. The computer readable storage medium could be a non-transitory computer readable storage medium.

[0025] According to a tenth aspect there is presented system comprising a first radio transceiver device according to the second or third aspect and a second radio transceiver device according to the sixth or seventh aspect.

[0026] Advantageously, these aspects address the above issues associated with traditional link adaptation for the downlink control channel. Advantageously, these aspects enable both faster and more accurate link adaptation for the downlink control channel.

[0027] Advantageously, in turn, this allows the resource consumption on the downlink control channel to be reduced.

[0028] Advantageously, in turn, this leads to higher throughput and lower latency in the network.

[0029] Other objectives, features and advantages of the enclosed embodiments will be apparent from the following detailed disclosure, from the attached dependent claims as well as from the drawings.

[0030] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a / an / the element, apparatus, component, means, module, step, etc." are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, module, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

[0031] BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The inventive concept is now described, by way of example, with reference to the accompanying drawings, in which:

[0033] Fig. 1 is a schematic diagram illustrating communications networks according to embodiments;

[0034] Figs. 2, 3, and 4 are flowcharts of methods according to embodiments;

[0035] Fig. 5 is a schematic illustration of monitored CCEs according to an embodiment;

[0036] Fig. 6 is a signaling diagram according to an embodiment;

[0037] Fig. 7 is a schematic diagram showing functional units of a first radio transceiver device according to an embodiment;

[0038] Fig. 8 is a schematic diagram showing functional modules of a first radio transceiver device according to an embodiment;

[0039] Fig. 9 is a schematic diagram showing functional units of a second radio transceiver device according to an embodiment;

[0040] Fig. 10 is a schematic diagram showing functional modules of a second radio transceiver device according to an embodiment; and Fig. 11 shows one example of a computer program product comprising computer readable means according to an embodiment.

[0041] DETAILED DESCRIPTION

[0042] The inventive concept will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the inventive concept are shown. This inventive concept may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive concept to those skilled in the art. Like numbers refer to like elements throughout the description. Any step or feature illustrated by dashed lines should be regarded as optional.

[0043] Fig. 1 is a schematic diagram illustrating communications networks where embodiments presented herein can be applied. The communications network in Fig. 1(a) comprises a first radio transceiver device 200a implemented as a network node 200a and a second radio transceiver device 300 implemented as a user equipment 300. Hence, in Fig. 1(a) the first radio transceiver device 200a communicates in the downlink (DL) to the second radio transceiver device 300 and the second radio transceiver device 300 communicates in the uplink (UL) to the first radio transceiver device 200a. The communications network in Fig. 1(b) comprises a first radio transceiver device 200b implemented as a first user equipment 200b and a second radio transceiver device 300 implemented as a second user equipment 300. Hence, in Fig. 1(b) the first radio transceiver device 200b and the second radio transceiver device 300 communicate with each other over sidelinks (SL). There can be different examples of network nodes. In some non-limiting examples, the network node is any of: a (radio) access network node, radio base station, base transceiver station, node B (NB), evolved node B (eNB), gNB, access point, access node, transmission and reception (TRP) point, integrated access and backhaul node (IAB). There can be different examples of user equipment. In some non-limiting examples, the user equipment is any of: a portable wireless device, mobile station, mobile phone, handset, wireless local loop phone, smartphone, laptop computer, tablet computer, wireless modem, wireless sensor device, network equipped vehicle.

[0044] As noted above, there is a need for more efficient (e.g., faster, and / or more accurate) link adaptation for the downlink control channel. However, it is here noted that the same principles ally also for link adaptation for the sidelink control channel. The term control channel will therefore be used in this disclosure to represent both the downlink control channel and the sidelink control channel.

[0045] In further detail, one way to overcome the above identified issues to improve the link adaptation of the downlink control channel is to use the measurements pertaining to the data channel also for the link adaptation of the control channel. In this case, a large offset can be added to cater for the worst case. However, this often leads to over allocation of resources for the downlink control channel, thus wasting network resources and reducing capacity and / or throughput. Another way to overcome the above identified issues to improve the link adaptation of the downlink control channel is to use outer control loop correction, where the estimated quality of the downlink control channel is updated based on whether the DCI sent to the user equipment was received or not. Thereby, for correctly received DCIs a more aggressive (i.e., less robust) link adaptation is applied whilst for non-received a less aggressive (i.e., more robust) aggregation level is selected. This is however a slow method if a low error rate on the downlink control channel is targeted, especially since detection of DCIs can be hard.

[0046] The embodiments disclosed herein therefore relate to techniques for control channel link adaptation and control channel quality reporting. In order to obtain such techniques, there is provided a first radio transceiver device 200a, 200b, a method performed by the first radio transceiver device 200a, 200b, a computer program product comprising code, for example in the form of a computer program, that when run on processing circuitry of the first radio transceiver device 200a, 200b, causes the first radio transceiver device 200a, 200b to perform the method. In order to obtain such techniques there is further provided a second radio transceiver device 300, a method performed by the second radio transceiver device 300, and a computer program product comprising code, for example in the form of a computer program, that when run on processing circuitry of the second radio transceiver device 300, causes the second radio transceiver device 300 to perform the method.

[0047] Reference is now made to Fig. 2 illustrating a method for control channel link adaptation as performed by the first radio transceiver device 200a, 200b according to an embodiment.

[0048] S106: The first radio transceiver device 200a, 200b sends first control information over a control channel to the second radio transceiver device 300. A transmission setting is applied to the control channel whilst the first control information is sent.

[0049] S108: The first radio transceiver device 200a, 200b receives a report of received quality of the control channel from the second radio transceiver device 300. The received quality here refers to the quality of the control channel as received by the second radio transceiver device 300.

[0050] SI 10: The first radio transceiver device 200a, 200b sends second control information over the control channel to the second radio transceiver device 300. The transmission setting as applied to the control channel whilst the second control information is sent is updated at least partly based on the received report.

[0051] Advantageously, this method addresses the above issues associated with traditional link adaptation for the downlink control channel.

[0052] Advantageously, this method enables both enable faster and more accurate link adaptation for the downlink control channel. Advantageously, in turn, this method allows the resource consumption on the downlink control channel to be reduced.

[0053] Advantageously, in turn, this method leads to higher throughput and lower latency in the network.

[0054] Embodiments relating to further details of control channel link adaptation as performed by the first radio transceiver device 200a, 200b will now be disclosed with continued reference to Fig. 2.

[0055] There could be different ways for the first radio transceiver device 200a, 200b to cause the second radio transceiver device 300 to send the report of received quality of the control channel that is received by the first radio transceiver device 200a, 200b in step S108.

[0056] In some aspects, the first radio transceiver device 200a, 200b configures the second radio transceiver device 300 for the reporting. In particular, in some embodiments, the first radio transceiver device 200a, 200b is configured to perform (optional) step SI 02.

[0057] S102: The first radio transceiver device 200a, 200b sends configuration information to the second radio transceiver device 300. The configuration information comprises configuration for reporting of the received quality of the control channel.

[0058] In this respect, there can be different ways in which the configuration information is sent in step S102. For example, the configuration information might be sent using broadcast or unicast radio resource control (RRC) signaling. If sent using broadcast transmission the configuration information can be common for a group of second radio transceiver devices 300. If sent using RRC signaling the configuration information can be specified for one particular second radio transceiver device 300.

[0059] Further aspects of the configuration information will be disclosed below in conjunction with the description of Fig. 4.

[0060] Additionally or alternatively, the trigger can be sent in a legacy DCI, potentially specifying which CCE indices for the second radio transceiver device 300 to measure on. In some examples, one or more search space candidates are indicated. That is, the second radio transceiver device 300 measures on the CCEs associated with the one or more indicated search space candidates.

[0061] In some aspects, the first radio transceiver device 200a, 200b sends one or more triggers to the second radio transceiver device 300 for the reporting. In particular, in some embodiments, the first radio transceiver device 200a, 200b is configured to perform (optional) step SI 04.

[0062] S 104: The first radio transceiver device 200a, 200b sends a trigger to the second radio transceiver device 300 for the second radio transceiver device 300 to send the report of received quality of the control channel. In this respect, there can be different ways in which the trigger is sent in step SI 04. For example, the trigger might be sent as DCI, as sidelink control information, in a medium access control control element (MAC CE), or using RRC signaling.

[0063] In some examples, the trigger is in step SI 04 sent in same way as the configuration information in step S102.

[0064] Further aspects of different types of triggers will be disclosed next.

[0065] The trigger could be explicit and imply that the second radio transceiver device 300 is to send the report of received quality of the control channel upon reception of the trigger from the first radio transceiver device 200a, 200b. In some examples the trigger is sent in a DCI field indicating a downlink control channel CSI request. Then, when the second radio transceiver device 300 detects the DCI, the second radio transceiver device 300 sends the quality report based on measurements on the downlink control channel that carried the DCI.

[0066] The trigger could be implicit and imply that the second radio transceiver device 300 is to send the report of received quality of the control channel upon reception of each received occurrence of control information from the first radio transceiver device 200a, 200b.

[0067] In some examples, the trigger implies that the second radio transceiver device 300 is to send the report of received quality of the control channel upon a mismatch between the number of actually received occurrence of control information from the first radio transceiver device 200a, 200b and the number transmitted occurrences of the control information as indicated by the first radio transceiver device 200a, 200b, over some specific time period.

[0068] The trigger could imply that the second radio transceiver device 300 is to send the report of received quality of the control channel upon some timer expiring at the second radio transceiver device 300. The timer might start at some pre-defined time or on reception of information on the control channel by the second radio transceiver device 300. Thus, upon the expiry of the timer, the report is transmitted by the second radio transceiver device 300.

[0069] The trigger could imply that the second radio transceiver device 300 is to send the report of received quality of the control channel after the second radio transceiver device 300 has received some configured number N1 >0 of occurrences of control information from the first radio transceiver device 200a, 200b. The trigger could thus specify a counter. In this respect, there could be different types of counters; counters may be joint or different for different search spaces, search space sets, Control Resource Sets (CORESETs) and DCI types / formats.

[0070] The trigger could imply that the second radio transceiver device 300 is to send the report of received quality of the control channel upon the quality at which the control information is received by the second radio transceiver device 300 satisfies some condition. For example, the trigger could imply that the second radio transceiver device 300 is to send the report of received quality of the control channel upon the quality at which the control information is received deviates more than some percentage from some required quality value. In this respect, the second radio transceiver device 300 might be configured for averaging of the received quality of several occurrences of received control information. For example, the trigger could imply that the second radio transceiver device 300 is to send the report of received quality of the control channel upon the quality at which the control information is received differs more than some threshold value from when the reporting lastly was made.

[0071] The trigger could imply that the second radio transceiver device 300 is to make periodic follow-ups. That is, after any of the above-mentioned trigger condition for the second radio transceiver device 300 to send the report of received quality of the control channel has been met, there can be N2 > 0 number of followup reports according to some periodicity provided, for example, in milliseconds, slots or symbols.

[0072] The trigger could be based on mobility measurements as made by the second radio transceiver device 300. For example, the second radio transceiver device 300 might be triggered to send the report of received quality of the control channel if the reference signal received power (RSRP), the reference signal received quality (RSRQ), and / or the signal to interference plus noise ratio (SINR) measured on a reference signal, such as a CSI-RS, transmitted from a primary cell (PCell) or secondary cell (SCell) drops below some threshold value.

[0073] As disclosed above, the transmission setting as applied to the control channel whilst the second control information is sent is updated at least partly based on the received report. Further aspects relating thereto will be disclosed next.

[0074] In some embodiments, transmission setting pertains to link adaptation in terms of any, or any combination, of: aggregation level, transmit power, precoder, code rate. In further detail, in some aspects, a smaller aggregation level and / or less power (compared to the transmission of the first control information is sent) is used if the report indicates good quality. Likewise, in some aspects, a larger aggregation level and / or more power (compared to the transmission of the first control information is sent) is used if the report indicates bad quality. Good / bad quality could be reflected by an explicit quality measure in the report or by comparing counters with stored information about number of transmitted occurrences of the first control information. That is, in some embodiments, the worse the received quality of the control channel is reported, the more robust the transmission setting as applied to the control channel whilst the second control information is sent. That the transmission setting becomes more robust can, for example, be achieved by using a higher aggregation level and / or by increasing the transmission power. In this respect, there could be either a linear, a non-linear, or a step-wise relation between the reported received quality of the control channel and the selected transmission setting as applied to the control channel whilst the second control information. In one example, the second radio transceiver device 300 indicates a certain number of missed DCIs. At the first radio transceiver device 200a, 200b, if the number of missed DCIs are within some accepted limit (e.g., below a threshold, such as less than 5% or even less than 1%) the first radio transceiver device 200a, 200b can decide to not change any transmission setting. However, if the number of missed DCI still is within the accepted limit and the current transmission setting is not spectrum efficient, the first radio transceiver device 200a, 200b can decide to use reduce the aggregation level to increase spectrum efficiency. Further, if the number of missed DCIs is larger than the accepted limit but still smaller than some other, further limit (such as 10%), then the first radio transceiver device 200a, 200b may decide to increase the aggregation level by one step. Still further, if the number of missed DCIs is larger than the further limit, the first radio transceiver device 200a, 200bmay revert to using the most robust transmission settings for the second radio transceiver device 300.

[0075] In some aspects, there is one report of received quality of the control channel for each carrier, or cell. In some aspects, the herein disclosed embodiments can also be applied when carrier aggregation is used. In further detail, two or more carriers, or cells, might form a control channel quality reporting set. The report triggering, etc. can then be applied among all carriers, or cells, within one control channel quality reporting set, instead of per each individual carrier or cell. In some embodiments, the report of received quality of the control channel thus at least pertains to a set of carriers on which the first control information and the second control information is sent, and the transmission setting as applied to the control channel whilst the second control information is sent is updated for this set of carriers. The grouping of the carriers, or cells, might be based on the assumption that the utilization and link adaptation for the carriers, or cells, within each group is expected to be similar.

[0076] Further, the first radio transceiver device 200a, 200b may take input from one or multiple received reports when deciding on resources for the transmission of the second control information. In this way, the first radio transceiver device 200a, 200b might, for example, deciding on the resources for transmission based on an average, such as a weighted average, of these multiple received reports.

[0077] Reference is now made to Fig. 3 illustrating a method for control channel quality reporting as performed by the second radio transceiver device 300 according to an embodiment.

[0078] S206: The second radio transceiver device 300 receives first control information over a control channel from the first radio transceiver device 200a, 200b.

[0079] S208: The second radio transceiver device 300 sends a report of received quality of the control channel to the first radio transceiver device 200a, 200b when a trigger condition is fulfilled.

[0080] Advantageously, this method addresses the above issues associated with traditional link adaptation for the downlink control channel. Advantageously, this method enables both enable faster and more accurate link adaptation for the downlink control channel.

[0081] Advantageously, in turn, this method allows the resource consumption on the downlink control channel to be reduced.

[0082] Advantageously, in turn, this method leads to higher throughput and lower latency in the network.

[0083] Embodiments relating to further details of control channel quality reporting as performed by the second radio transceiver device 300 will now be disclosed with continued reference to Fig. 3.

[0084] In general terms, there can be different conditions for the second radio transceiver device 300 to generate the report of received quality and actually send the report of received quality, as in step S208.

[0085] Hence, in some aspects, the second radio transceiver device 300 generates the report of received quality but does not send it until another trigger condition is fulfdled. That is, in some embodiments, the trigger condition in step S208 is a first trigger condition, and the second radio transceiver device 300 is configured with a second trigger condition for generating the report of received quality.

[0086] Further, as disclosed above, the first radio transceiver device 200a, 200b might send configuration information to the second radio transceiver device 300, as in optional step SI 02. Therefore, in some embodiments, the second radio transceiver device 300 is configured to perform (optional) step S202.

[0087] S202: The second radio transceiver device 300 receives configuration information from the first radio transceiver device 200a, 200b. The configuration information comprises configuration for reporting of the received quality of the control channel.

[0088] In other aspects, the configuration for reporting of the received quality of the control channel is obtained from specification by, for example, being hardcoded in the second radio transceiver device 300.

[0089] As further disclosed above, the first radio transceiver device 200a, 200b might send a trigger to the second radio transceiver device 300, as in optional step S104. Therefore, in some embodiments, the second radio transceiver device 300 is configured to perform (optional) step S204.

[0090] S204: The second radio transceiver device 300 receives a trigger from the first radio transceiver device 200a, 200b for the second radio transceiver device 300 to send the report of received quality of the control channel. The trigger condition is fulfilled when the trigger is received.

[0091] Examples of triggers for the second radio transceiver device 300 to send the report of received quality of the control channel have been disclosed above. Those examples of triggers apply here as well. Thus, in summary, in some examples, the trigger condition is fulfilled according to any, or any combination, of: when a predetermined number of received instances of the first control information is received, there is a mismatch between the number of received instances of the first control information and the number of instances of the first control information indicated by the first radio transceiver device 200a, 200b to be received by the second radio transceiver device 300, when a timer expires, when the received quality of the control channel fulfils a first quality condition, when mobility measurements made by the second radio transceiver device 300 fulfil a quality condition, when a comparison of first control information as received in at least two different search spaces fulfils a second quality condition.

[0092] Further in this respect, hysteresis can be considered in the evaluation of the events. For example, an event for transmission of a quality report (e.g., when the first and / or the second quality condition is / are fulfilled) is that the quality of the control information plus some hysteresis value is smaller than some threshold value, while stopping transmission of the report according to the same event (e.g., when neither the first nor the second quality condition is fulfilled) is that the quality of the control information minus some hysteresis value is higher than the threshold value.

[0093] As already disclosed with reference to the method performed by the first radio transceiver device 200a, 200b, there could be different parameters reported by the second radio transceiver device 300 in the report of received quality of the control channel that is sent by the second radio transceiver device 300 to the first radio transceiver device 200a, 200b in step S208. Further aspects of the content of the report of received quality will be disclosed next.

[0094] In some non-limiting examples, the report of received quality of the control channel comprises any, or any combination of: a counter value of the number of received instances of control information from the first radio transceiver device 200a, 200b, a quality measure of received control information from the first radio transceiver device 200a, 200b, an interference measure of resources on which control information is received from the first radio transceiver device 200a, 200b, an indication of successfully received control information from the first radio transceiver device 200a, 200b, an indication of a time period over which information in the report was compiled.

[0095] The counter value could be separate or joint per aggregation levels and / or control information type.

[0096] The quality measure could be expressed in SINR or relative CCE aggregation need, could be a single value jointly computed over a number of occasions of received control information or a statistical measure e.g., a histogram, could be separate per aggregation level and / or control information types and / or search space, could be aggregate or separate measure for configured CORESETs on which the second radio transceiver device 300 monitors the control channel. The interference measure could contain pure received signal strength indicator (RSSI) measurements on resource elements (REs) or RSSI on measurements on DM-RS. The assessment for a given UE could also be performed on DM-RS on REs that do not carry any control information for the second radio transceiver device 300. The interference measure could be reported as an absolute value or relative to a CSI report for the data channel, expressed in dB or CQI offset; the offset could also include a rank difference. The interference measure could be based on a Resource for Interference Measurement (CSI- IM) which the second radio transceiver device 300 shall rate-match the control channel around. The CSI- IM could be semi-statically configured for the CORESET bandwidth or a part of the CORESET bandwidth. In some cases, frequency-hopping is used for the CSI-IM. The CSI-IM could be semi- statically configured to be present for set of CCEs. For example, at a first control channel monitoring occasions a CSI-IM is present in a first set of CCEs while in a second control channel monitoring occasion a CSI-IM is present in a second set of CCEs. The CSI-IM could be semi-statically configured to present in set of search space candidates. In such cases, there may be specific rules for cases where two search space candidates have overlapping CCE where for an overlapping CCE the first search space candidate is configured to have CSI-IM present while the second search space candidate does not. The rule in such cases could be resolved such that for such overlapping CCEs the second radio transceiver device 300 shall assume CSI-IM to be present (or not present). In some examples, the presence of CSI-IM may be selectively activated and deactivated by a MAC CE.

[0097] In some examples where the report of received quality of the control channel comprises interference measures, the report could be an explicit interference report, e.g. a wide-band or sub-band interference report. For example, the second radio transceiver device 300 might estimate interference strengths q0, ..., qW-i for N sub-bands (or CCEs or the resource blocks (RBs) of the measured CCEs) and report the average or percentile value of the interference strength. In some examples, the second radio transceiver device 300 estimates N interference and noise covariance matrices Qo, ..., QN- and report a quantization matrix Q defined as:

[0098] The indication of successfully received control information from the first radio transceiver device 200a, 200b could be expressed in terms of a bitmap extending over some specific period of time, indicating in which (for example) slots the control information was successfully received.

[0099] The indication of the time period could be a time stamp indicating the time period over which the quality was measured. The time stamp could be expressed in relation to system frame number or relative content in received occasions of the control information, for example Downlink Assignment Index (DAI) values. As further disclosed above, there could be one report per carrier, or cell, or one report per control channel quality reporting set, where each control channel quality reporting set might include two or more carriers, or cells.

[0100] There could be different ways for the second radio transceiver device 300 to send the report of received quality of the control channel to the first radio transceiver device 200a, 200b in step S208.

[0101] In some aspects, the report of received quality is sent as an uplink (or a sidelink) physical control message on an uplink (or sidelink) control channel or together with payload data. In some aspects, the report of received quality is sent as a MAC CE together with an uplink (or sidelink) data transmission that might, or might not, comprise also payload data. The second radio transceiver device 300 could then send the report when uplink (or sidelink) data resources become available, subject to prioritization rules among other control and data available. If the report is sent via an MAC CE, then a logical channel ID (LCID) or enhanced LCID (eLCID) can be assigned to indicate this MAC CE in the MAC protocol data unit (PDU) header. That is, in some examples, the report of received quality of the control channel is sent as a MAC CE, and a logical channel identifier is assigned to indicate the MAC CE. Also if the transmission of the report is dynamically triggered by some DCI, the same DCI could allocate uplink resources for the transmission of the report.

[0102] In some aspects, the report of received quality is sent as an RRC layer report. In some aspects, the report of received quality is sent together with a CSI report reflecting the received quality of a downlink data channel. In general terms, the report of received quality of the control channel might be sent either together with, or separately from, a report of received quality of a data channel.

[0103] In case there is a lack of resources to transmit the report could lead the second radio transceiver device 300 to trigger a buffer status report (BSR) and then subsequently trigger a scheduling request (SR) to request uplink (or sidelink) resources. In another variant, the lack of resources does not trigger any BSR, which assumes that the first radio transceiver device 200a, 200b, or some other entity in the network, is aware of the reporting and knows always to allocate resources to transmit the report. the report of received quality of the control channel is sent either in a physical control message on a control channel or data channel, as a MC CE together with a data transmission, or as a RRC layer report.

[0104] Further aspects of the configuration information will be disclosed next with reference to the flowchart of Fig. 4. According to the example in Fig. 4, the configuration information comprises configuration for the second radio transceiver devices 300 to report the received quality of the control channel using a specific DCI format (DCI x) scrambled with specific RNTI, (RNTI_y) that is shared with multiple second radio transceiver devices 300. Such a DCI might comprise information of how, and / or what, to measure on and report for different PDCCH search spaces. In this way, a second radio transceiver device 300 assigned with RNTI_y monitors the common search space (CSS) for DCI x (step S301). If the CRC checks out with the RNTI_y (step S302) then the second radio transceiver device 300 decodes the DCI_x (step

[0105] 5303), and otherwise the second radio transceiver device 300 waits for the next monitor occasion (step

[0106] 5304). In one option, the DCI x signals which CCE indices of what search space and CORESET for the second radio transceiver devices 300 to monitor (step S305). Since in the device-specific search space (USS) the CCEs that the second radio transceiver device 300 monitors are random and change overtime, it is possible that a USS of the second radio transceiver device 300 will not monitor some CCEs that are indicated by DCI_x. Thus, the second radio transceiver device 300 might first determine the overlap, or intersection, between the signalled CCEs and the CCEs it monitors as dictated by USS rules (step S306). Then, the second radio transceiver device 300 can determine the overlapped CCEs and perform channel estimation using the DM-RSs of the CCEs and create a report (step S307), which is then stored and / or sent (step S308). Hence, in some embodiments, the configuration information is sent with a RNTI that is shared among at least two second radio transceiver devices 300, and the configuration information comprises information of search spaces for these at least two second radio transceiver devices 300. Further, the configuration information might specify any, or any combination, of: a timer value, periodicity, threshold, physical resource for the reporting of the received quality of the control channel.

[0107] Reference is next made to Fig. 5 which illustrates which CCEs that are monitored by different second radio transceiver devices 300, implemented as user equipment denoted UE1, UE2, UE3, UE4, together with an indication of the CCEs indicated by DCI x. As follows from the figure the CCEs indicated by the DCI_x are [0:3, 8: 15, 19:26], Hence, channel assessment will, by UE1, UE2, UE3, UE4, only be performed for these CCEs. As further follows from the figure, UE1 will perform channel assessment, and in particular measure the received quality of the control channel, for CCE indices [0:3, 8: 15,19:26], UE2 for CCE indices [8: 15, 19:24], UE3 for CCE indices [8: 15, 19:26], and UE4 for CCE indices [8: 11, 19:26],

[0108] One particular embodiment for control channel quality reporting and control channel link adaptation based on at least some of the above disclosed embodiments will now be disclosed in detail with reference to the signaling diagram of Fig. 6. In this embodiment the first radio transceiver device 200a is a network node and the second radio transceiver device 300 is a user equipment. Further, the control information is DCI that is sent by the network node on the PDCCH and the report of received quality as sent by the user equipment thus pertains to the received quality of the DCI.

[0109] S401 : The network node (NN) configures the user equipment (UE) for PDCCH quality measurements and reporting.

[0110] S402: The network node sends a scheduling assignment to the user equipment defining how the user equipment is to send the report of received quality of the DCI to the network node.

[0111] S403 : The network node sends DCI on the PDCCH and the user equipment performs measurements of the received quality of the DCI. Step S404 is entered if the user equipment is triggered to send its report of the received quality of the DCI to the network node upon an explicit request from the network node.

[0112] S404: The network node sends a request to the user equipment for the user equipment to report the received quality of the DCI.

[0113] S405: The user equipment sends the report of the received quality of the DCI to the network node.

[0114] S406: The network node adjusts its link adaptation according to the report of the received quality of the DCI.

[0115] Step S407 is entered if the user equipment is triggered to send its report of the received quality of the DCI to the network node without any explicit request from the network node.

[0116] S407 : Some condition is fulfilled that triggers the user equipment to send the report of the received quality of the DCI. Examples of such conditions have been disclosed above.

[0117] S408: The user equipment sends the report the received quality of the DCI to the network node.

[0118] S409: The network node adjusts its link adaptation according to the report of the received quality of the DCI.

[0119] Fig. 7 schematically illustrates, in terms of a number of functional units, the components of a first radio transceiver device 200a, 200b according to an embodiment. Processing circuitry 210 is provided using any combination of one or more of a suitable central processing unit (CPU), multiprocessor, microcontroller, digital signal processor (DSP), etc., capable of executing software instructions stored in a computer program product 1110a (as in Fig. 11), e.g. in the form of a storage medium 230. The processing circuitry 210 may further be provided as at least one application specific integrated circuit (ASIC), or field programmable gate array (FPGA).

[0120] Particularly, the processing circuitry 210 is configured to cause the first radio transceiver device 200a, 200b to perform a set of operations, or steps, as disclosed above. For example, the storage medium 230 may store the set of operations, and the processing circuitry 210 may be configured to retrieve the set of operations from the storage medium 230 to cause the first radio transceiver device 200a, 200b to perform the set of operations. The set of operations may be provided as a set of executable instructions. Thus the processing circuitry 210 is thereby arranged to execute methods as herein disclosed.

[0121] The storage medium 230 may also comprise persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, solid state memory or even remotely mounted memory. The first radio transceiver device 200a, 200b may further comprise a communications (comm.) interface 220 for communications with other entities, functions, nodes, and devices, as in Fig. 1. As such the communications interface 220 may comprise one or more transmitters and receivers, comprising analogue and digital components.

[0122] The processing circuitry 210 controls the general operation of the first radio transceiver device 200a, 200b e.g. by sending data and control signals to the communications interface 220 and the storage medium 230, by receiving data and reports from the communications interface 220, and by retrieving data and instructions from the storage medium 230. Other components, as well as the related functionality, of the first radio transceiver device 200a, 200b are omitted in order not to obscure the concepts presented herein.

[0123] Fig. 8 schematically illustrates, in terms of a number of functional modules, the components of a first radio transceiver device 200a, 200b according to an embodiment. The first radio transceiver device 200a, 200b of Fig. 8 comprises a number of functional modules; a send module 210c configured to perform step SI 06, a receive module 210d configured to perform step S108, and a send module 210e configured to perform step SI 10. The first radio transceiver device 200a, 200b of Fig. 8 may further comprise a number of optional functional modules, such as any of a send module 210a configured to perform step SI 02, and a send module 210b configured to perform step SI 04. In general terms, each functional module 210a:210e may be implemented in hardware or in software. Preferably, one or more or all functional modules 210a:210e may be implemented by the processing circuitry 210, possibly in cooperation with the communications interface 220 and / or the storage medium 230. The processing circuitry 210 may thus be arranged to from the storage medium 230 fetch instructions as provided by a functional module 210a:210e and to execute these instructions, thereby performing any steps of the first radio transceiver device 200a, 200b as disclosed herein.

[0124] Fig. 9 schematically illustrates, in terms of a number of functional units, the components of a second radio transceiver device 300 according to an embodiment. Processing circuitry 310 is provided using any combination of one or more of a suitable central processing unit (CPU), multiprocessor, microcontroller, digital signal processor (DSP), etc., capable of executing software instructions stored in a computer program product 1110b (as in Fig. 11), e.g. in the form of a storage medium 330. The processing circuitry 310 may further be provided as at least one application specific integrated circuit (ASIC), or field programmable gate array (FPGA).

[0125] Particularly, the processing circuitry 310 is configured to cause the second radio transceiver device 300 to perform a set of operations, or steps, as disclosed above. For example, the storage medium 330 may store the set of operations, and the processing circuitry 310 may be configured to retrieve the set of operations from the storage medium 330 to cause the second radio transceiver device 300 to perform the set of operations. The set of operations may be provided as a set of executable instructions. Thus the processing circuitry 310 is thereby arranged to execute methods as herein disclosed. The storage medium 330 may also comprise persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, solid state memory or even remotely mounted memory.

[0126] The second radio transceiver device 300 may further comprise a communications interface 320 for communications with other entities, functions, nodes, and devices, as in Fig. 1. As such the communications interface 320 may comprise one or more transmitters and receivers, comprising analogue and digital components.

[0127] The processing circuitry 310 controls the general operation of the second radio transceiver device 300 e.g. by sending data and control signals to the communications interface 320 and the storage medium 330, by receiving data and reports from the communications interface 320, and by retrieving data and instructions from the storage medium 330. Other components, as well as the related functionality, of the second radio transceiver device 300 are omitted in order not to obscure the concepts presented herein.

[0128] Fig. 10 schematically illustrates, in terms of a number of functional modules, the components of a second radio transceiver device 300 according to an embodiment. The second radio transceiver device 300 of Fig. 10 comprises a number of functional modules; a receive module 310c configured to perform step S206, and a send module 3 lOd configured to perform step S208. The second radio transceiver device 300 of Fig. 10 may further comprise a number of optional functional modules, such as any of a receive module 310a configured to perform step S202, and a receive module 310b configured to perform step S204. In general terms, each functional module 310a: 3 lOd may be implemented in hardware or in software. Preferably, one or more or all functional modules 310a: 3 lOd may be implemented by the processing circuitry 310, possibly in cooperation with the communications interface 320 and / or the storage medium 330. The processing circuitry 310 may thus be arranged to from the storage medium 330 fetch instructions as provided by a functional module 310a:310d and to execute these instructions, thereby performing any steps of the second radio transceiver device 300 as disclosed herein.

[0129] The first radio transceiver device 200a, 200b and / or the second radio transceiver device 300 may be provided as a standalone device or as a part of at least one further device. For example, the first radio transceiver device 200a, 200b and / or the second radio transceiver device 300 may be provided in a node of the radio access network or in a node of the core network. Alternatively, functionality of the first radio transceiver device 200a, 200b and / or the second radio transceiver device 300 may be distributed between at least two devices, or nodes. These at least two nodes, or devices, may either be part of the same network part (such as the radio access network or the core network) or may be spread between at least two such network parts. In general terms, instructions that are required to be performed in real time may be performed in a device, or node, operatively closer to the cell than instructions that are not required to be performed in real time. Thus, a first portion of the instructions performed by the first radio transceiver device 200a, 200b and / or the second radio transceiver device 300 may be executed in a first device, and a second portion of the instructions performed by the first radio transceiver device 200a, 200b and / or the second radio transceiver device 300 may be executed in a second device; the herein disclosed embodiments are not limited to any particular number of devices on which the instructions performed by the first radio transceiver device 200a, 200b and / or the second radio transceiver device 300 may be executed. Hence, the methods according to the herein disclosed embodiments are suitable to be performed by a first radio transceiver device 200a, 200b and / or the second radio transceiver device 300 residing in a cloud computational environment. Therefore, although a single processing circuitry 210, 310 is illustrated in Figs. 7 and 9 the processing circuitry 210, 310 may be distributed among a plurality of devices, or nodes. The same applies to the functional modules 210a:210e, 310a:3 lOd of Figs. 8 and 10 and the computer programs 1120a, 1120b ofFig. 11.

[0130] Some (radio) access network architectures define network nodes (or gNBs) comprising multiple component parts or nodes: a central unit (CU), one or more distributed units (DUs), and one or more radio units (RUs). The protocol layer stack of the network node is divided between the CU, the DUs and the RUs, with one or more lower layers of the stack implemented in the RUs, and one or more higher layers of the stack implemented in the CU and / or DUs. The CU is coupled to the DUs via a fronthaul higher layer split (HUS) network; the CU / DUs are connected to the RUs via a fronthaul lower-layer split (UUS) network. The DU may be combined with the CU in some embodiments, where a combined DU / CU may be referred to as a CU or simply a baseband unit. A communication link for communication of user data messages or packets between the RU and the baseband unit, CU, or DU is referred to as a fronthaul network or interface. Messages or packets may be transmitted from the network node in the downlink (i.e., from the CU to the RU) or received by the network node in the uplink (i.e., from the RU to the CU).

[0131] Fig. 11 shows one example of a computer program product 1110a, 1110b comprising computer readable means 1130. On this computer readable means 1130, a computer program 1120a can be stored, which computer program 1120a can cause the processing circuitry 210 and thereto operatively coupled entities and devices, such as the communications interface 220 and the storage medium 230, to execute methods according to embodiments described herein. The computer program 1120a and / or computer program product 1110a may thus provide means for performing any steps of the first radio transceiver device 200a, 200b as herein disclosed. On this computer readable means 1130, a computer program 1120b can be stored, which computer program 1120b can cause the processing circuitry 310 and thereto operatively coupled entities and devices, such as the communications interface 320 and the storage medium 330, to execute methods according to embodiments described herein. The computer program 1120b and / or computer program product 1110b may thus provide means for performing any steps of the second radio transceiver device 300 as herein disclosed.

[0132] In the example ofFig. 11, the computer program product 1110a, 1110b is illustrated as an optical disc, such as a CD (compact disc) or a DVD (digital versatile disc) or a Blu-Ray disc. The computer program product 1110a, 1110b could also be embodied as a memory, such as a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM), or an electrically erasable programmable read-only memory (EEPROM) and more particularly as a non-volatile storage medium of a device in an external memory such as a USB (Universal Serial Bus) memory or a Flash memory, such as a compact Flash memory. Thus, while the computer program 1120a, 1120b is here schematically shown as a track on the depicted optical disk, the computer program 1120a, 1120b can be stored in any way which is suitable for the computer program product 1110a, 1110b.

[0133] The inventive concept has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the inventive concept, as defined by the appended patent claims.

Claims

CLAIMS1. A method for control channel link adaptation, the method being performed by a first radio transceiver device (200a, 200b), the method comprising: sending (SI 06) first control information over a control channel to a second radio transceiver device (300), wherein a transmission setting is applied to the control channel whilst the first control information is sent; receiving (S108) a report of received quality of the control channel from the second radio transceiver device (300); and sending (SI 10) second control information over the control channel to the second radio transceiver device (300), wherein the transmission setting as applied to the control channel whilst the second control information is sent is updated at least partly based on the received report.

2. The method according to claim 1, wherein the method further comprises: sending (SI 02) configuration information to the second radio transceiver device (300) comprising configuration for reporting of the received quality of the control channel.

3. The method according to claim 2, wherein the configuration information is sent using broadcast or unicast radio resource control signaling.

4. The method according to claim 2 or 3, wherein the configuration information is sent with a Radio Network Temporary Identifier that is shared among at least two second radio transceiver devices (300), and wherein the configuration information comprises information of search spaces for said at least two second radio transceiver devices (300).

5. The method according to claim 2, 3, or 4, wherein the configuration information specifies any, or any combination, of: a timer value, periodicity, threshold, physical resource for the reporting of the received quality of the control channel.

6. The method according to any preceding claim, wherein the method further comprises: sending (SI 04) a trigger to the second radio transceiver device (300) for the second radio transceiver device (300) to send the report of received quality of the control channel.

7. The method according to claim 6, wherein the trigger is sent as downlink control information, sidelink control information, in a medium access control control element, or using radio resource control signaling.

8. The method according to any preceding claim, wherein the transmission setting pertains to link adaptation in terms of any, or any combination, of: aggregation level, transmit power, precoder, code rate.

9. The method according to any preceding claim, wherein the worse the received quality of the control channel is reported, the more robust the transmission setting as applied to the control channel whilst the second control information is sent.

10. The method according to any preceding claim, wherein the report of received quality of the control channel pertains to a set of carriers on which the first control information and the second control information is sent, and wherein the transmission setting as applied to the control channel whilst the second control information is sent is updated for said set of carriers.

11. A method for control channel quality reporting, the method being performed by a second radio transceiver device (300), the method comprising: receiving (S206) first control information over a control channel from a first radio transceiver device (200a, 200b); and sending (S208) a report of received quality of the control channel to the first radio transceiver device (200a, 200b) when a trigger condition is fulfilled.

12. The method according to claim 11, wherein the trigger condition is a first trigger condition, and wherein the second radio transceiver device (300) is configured with a second trigger condition for generating the report of received quality.

13. The method according to claim 11 or 12, wherein the method further comprises: receiving (S202) configuration information from the first radio transceiver device (200a, 200b), the configuration information comprising configuration for reporting of the received quality of the control channel.

14. The method according to claim 11, wherein configuration for reporting of the received quality of the control channel is hardcoded in the second radio transceiver device (300).

15. The method according to any of claims 11 to 14, wherein the method further comprises: receiving (S204) a trigger from the first radio transceiver device (200a, 200b) for the second radio transceiver device (300) to send the report of received quality of the control channel, wherein the trigger condition is fulfilled when the trigger is received.

16. The method according to any of claims 11 to 15, wherein the trigger condition is fulfilled according to any, or any combination, of:when a predetermined number of received instances of the first control information is received, there is a mismatch between number of received instances of the first control information and number of instances of the first control information indicated by the first radio transceiver device (200a, 200b) to be received by the second radio transceiver device (300), when a timer expires, when the received quality of the control channel fulfils a first quality condition, when mobility measurements made by the second radio transceiver device (300) fulfil a quality condition, when a comparison of first control information as received in at least two different search spaces fulfils a second quality condition.

17. The method according to any of claims 11 to 16, wherein the report of received quality of the control channel comprises any, or any combination of: a counter value of number of received instances of control information from the first radio transceiver device (200a, 200b), a quality measure of received control information from the first radio transceiver device (200a, 200b), an interference measure of resources on which control information is received from the first radio transceiver device (200a, 200b), an indication of successfully received control information from the first radio transceiver device (200a, 200b), an indication of a time period over which information in the report was compiled.

18. The method according to any of claims 11 to 17, wherein the report of received quality of the control channel is sent either in a physical control message on a control channel or data channel, as a medium access control control element together with a data transmission, or as a radio resource control layer report.

19. The method according to claim 18, wherein the report of received quality of the control channel is sent either together with, or separately from, a report of received quality of a data channel.

20. The method according to any of claims 11 to 19, wherein the report of received quality of the control channel is sent as a medium access control control element, and wherein a logical channel identifier is assigned to indicate the medium access control control element.

21. The method according to any preceding claim, wherein the first radio transceiver device (200a, 200b) is a network node (200a) and the second radio transceiver device (300) is a user equipment (300).

22. The method according to any of claims 1 to 20, wherein the first radio transceiver device (200a, 200b) is a first user equipment (200b) and the second radio transceiver device (300) is a second user equipment (300).

23. A first radio transceiver device (200a, 200b) for control channel link adaptation, the first radio transceiver device (200a, 200b) comprising processing circuitry (210), the processing circuitry being configured to cause the first radio transceiver device (200a, 200b) to:send first control information over a control channel to a second radio transceiver device (300), wherein a transmission setting is applied to the control channel whilst the first control information is sent; receive a report of received quality of the control channel from the second radio transceiver device (300); and send second control information over the control channel to the second radio transceiver device (300), wherein the transmission setting as applied to the control channel whilst the second control information is sent is updated at least partly based on the received report.

24. A first radio transceiver device (200a, 200b) for control channel link adaptation, the first radio transceiver device (200a, 200b) comprising: a send module (210c) configured to send first control information over a control channel to a second radio transceiver device (300), wherein a transmission setting is applied to the control channel whilst the first control information is sent; a receive module (210d) configured to receive a report of received quality of the control channel from the second radio transceiver device (300); and a send module (210e) configured to send second control information over the control channel to the second radio transceiver device (300), wherein the transmission setting as applied to the control channel whilst the second control information is sent is updated at least partly based on the received report.

25. The first radio transceiver device (200a, 200b) according to claim 23 or 24, further being configured to perform the method according to any of claims 2 to 10.

26. A second radio transceiver device (300) for control channel quality reporting, the second radio transceiver device (300) comprising processing circuitry (310), the processing circuitry being configured to cause the second radio transceiver device (300) to: receive first control information over a control channel from a first radio transceiver device (200a, 200b); and send a report of received quality of the control channel to the first radio transceiver device (200a, 200b) when a trigger condition is fulfilled.

27. A second radio transceiver device (300) for control channel quality reporting, the second radio transceiver device (300) comprising: a receive module (310c) configured to receive first control information over a control channel from a first radio transceiver device (200a, 200b); anda send module (3 lOd) configured to send a report of received quality of the control channel to the first radio transceiver device (200a, 200b) when a trigger condition is fulfilled.

28. The second radio transceiver device (300) according to claim 26 or 27, further being configured to perform the method according to any of claims 12 to 20.

29. A system comprising a first radio transceiver device (200a, 200b) according to any of claims 23 to 25 and a second radio transceiver device (300) according to any of claims 26 to 28.

30. A computer program (1120a) for control channel link adaptation, the computer program comprising computer code which, when run on processing circuitry (210) of a first radio transceiver device (200a, 200b), causes the first radio transceiver device (200a, 200b) to: send (SI 06) first control information over a control channel to a second radio transceiver device (300), wherein a transmission setting is applied to the control channel whilst the first control information is sent; receive (SI 08) a report of received quality of the control channel from the second radio transceiver device (300); and send (SI 10) second control information over the control channel to the second radio transceiver device (300), wherein the transmission setting as applied to the control channel whilst the second control information is sent is updated at least partly based on the received report.

31. A computer program (1120b) for control channel quality reporting, the computer program comprising computer code which, when run on processing circuitry (310) of a second radio transceiver device (300), causes the second radio transceiver device (300) to: receive (S206) first control information over a control channel from a first radio transceiver device (200a, 200b); and send (S208) a report of received quality of the control channel to the first radio transceiver device (200a, 200b) when a trigger condition is fulfilled.

32. A computer program product (1110a, 1110b) comprising a computer program (1120a, 1120b) according to at least one of claims 30 and 31, and a computer readable storage medium (1130) on which the computer program is stored.

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