Methods and apparatuses for configuring a user equipment with a physical downlink control channel search space

Abstract

Embodiments described herein relate to methods and apparatuses for configuring a user equipment, UE, with a physical downlink control channel, PDCCH, search space. A method performed by a network node comprises transmitting a reduced aggregation level, AL, search space configuration to the UE, wherein the reduced AL search space configuration comprises only candidate sets of Control Channel Elements, CCEs, in ALs that are lower than a maximum aggregation level available in a communications network.

Description

METHODS AND APPARATUSES FOR CONFIGURING A USER EQUIPMENT WITH A PHYSICAE DOWNEINK CONTROE CHANNEL SEARCH SPACETECHNICAL FIELD111 Embodiments described herein relate to methods and apparatuses for configuring a user equipment, UE, with a physical downlink control channel, PDCCH, search space.BACKGROUND121 511 Generation (5G) New Radio (NR) Forwards Compatibility Design Philosophy[3] One big difference between 5GNR and 4thGeneration (4G) Long Term Evolution (LTE) is that 5G NR has a much higher ambition level when it comes to forward compatibility than 4G LTE. The manifestation of this is that the degree to which individual User Equipment (UEs) may be configured is much higher in NR compared to LTE.Hl The rationale is that future additions to the specification are much easier to make since the network should hopefully find ways to configure older UEs in ways which don’t conflict with newer UEs which have the new capabilities. That way, the standardization work does not need to predict every possible future addition to the standard.[5] This also means that all possible ways to make use of the current standard are not known at standardization. A good analogy here is a programming language: The specification in terms of syntax and semantics does not automatically mean that all useful programs which can be written in a programming language are known when the language is created.[6] NR Physical Downlink Control Channel (PDCCH)121 The PDCCH is where a base station (e.g. a gNB) sends Downlink Control Information (DCI) to aUE. The dominant type of DCI in today’s 5G networks comprises downlink assignments and uplink grants, both which informs the UE about a data transmission on the shared data channels (Physical Downlink Shared CHannel, PDSCH and Physical Uplink Shared CHannel, PUSCH respectively).181 A downlink assignment informs the UE that the gNB has transmitted data and requests that the UE attempts to receive it while an uplink grant requests that the UE makes a transmission. In both cases the DCI is a message with transmission parameters such as bandwidth and location of the transmission as well as the Modulation and Coding Scheme (MCS).21 The above the naturally begs the question how does the UE knows that there is a DCI to receive? The answer to that question is simply that it doesn’t. The UE must attempt to decode all possible DCIs in every possible transmission occasion with all possible transmission formats. This type of scheme is generally referred to as blind decoding.

[0010] Since the cost in terms of compute power (which translates both to chipset cost and battery consumption) of attempting to decode a possible DCI transmission is quite high it may be considered beneficial in the standardization work to keep the number of possible transmissions the UE must attempt to decode small.

[0011] The first way the standard keeps the number of possible transmissions the UE must attempt to decode small is to limit the number of different DCI message sizes. This is a very natural limitation since the control data needed to inform about a transmission is the same for every transmission.

[0012] The second way the standard keeps the number of possible transmissions the UE must attempt to decode small is to limit the allowed modulation and coding schemes possible. Just as for data transmissions, it may be considered important to select an appropriate amount of robustness for the DCI based on the channel quality. If the network uses the most robust format for all UEs, the capacity will be very poor and always using the least robust format may not be beneficial for coverage reasons. The standard currently only allows for QPSK modulation and does not allow for selecting a code rate explicitly. Instead, varying degrees of robustness comes from using different amount of spectrum resources and the code rate is then just derived from the message size and the amount of spectrum resources.

[0013] The third way the standard keeps the number of possible transmissions the UE must attempt to decode small is to limit the possible amounts of spectrum resources that can be used. The basic spectrum resource unit for the PDCCH is called a Control Channel Element (CCE) which comprises of the resource elements used in 6 Physical Resource Blocks (PRBs) over one OFDM symbol in time where on PRB is 12 OFDM subcarriers in frequency. The number of CCEs used for a PDCCH transmission is called the Aggregation Level (AL) and the standard restricts the possibilities to 1 CCE, 2 CCEs, 4 CCEs, 8 CCEs and 16 CCEs which is AL 1, AL 2, AL 4 etc. respectively. Since the DCI messages are typically in the same size order (generally smaller than 100 bits) this limitation is also quite straightforward.

[0014] The above set of limitations still yield an infeasibly large number of combinations to be decoded by the UE, especially in larger bandwidths. To further reduce the set ofcombinations the UE must attempt to receive, the standard states that the UE shall only listen to a subset of all the possible combinations. The set of possible combinations that a UE attempts to receive a set of DCI messages on is called a “search space set” and comprises of a set of CCEs for each AL, where each set of CCEs for a certain AL is called a candidate.

[0015] This search space set is determined based on the slot number and UE identity using a pseudo random number generation algorithm (defined in section 10.1 of 5G; NR; Physical layer procedures for control (3GPP TS 38.213 version 17.7.0 Release 17)) designed to prevent that UEs systematically have a large amount of search space overlap. Both the number of candidates in the search space and what CCEs might be part of the search space set is determined by the gNB and signaled using the Radio Resource Control (RRC) protocol.

[0016] Figure 1 illustrates an example of two search space for a UE 20955 in two different slots. It will be appreciated that a slot is a basic time unit within a frame and is used to transmit data and control information. In 5GNR, slots may have different lengths and configurations. The slot structure in 5G NR is more flexible than in previous generations, allowing for different slot lengths and configurations to be used within the same frame. This flexibility supports diverse use cases and allows for efficient spectrum utilization.

[0017] Figure 2 illustrates an example of two search space sets for the UE 4402 in two different slots.

[0018] In Figures 1 and 2, a candidate is illustrated as a contiguous set of boxes (or one box for AL 1). The x-axis shows the CCE index while the y-axis shows the AL. For example, if the network wants to send DCI to UE 4402 with AL4 it may be required to use CCEs 20-23 or 40-43 in slot 0 and CCEs 8-11 or 32-35 in slot 1. Figures 1 and 2 both have one row per AL for visibility purposes as candidates for different ALs often overlap.

[0019] There are two main constrains for configuring the search spaces which the network must respect to not exceed the UEs decoding capability. The first constraint is that the total number of candidates in all search space sets during a single slot must not exceed a certain number. This is referred to as the number of blind decode attempts herein.

[0020] The second constraint is that the total number of non-overlapping CCEs must not exceed a certain number. Non overlapping here just means that regardless of how many PDCCH candidates use a CCE index that index is only counted once. For example, looking at UE 4402 slot 1 in Figure CCE index 8 is used by both an AL 16, an AL8, and an AL4 candidate, but it is only counted as one non-overlapped CCE.

[0021] The exact numbers for the first constraint and the second constraint depend on the numerology and are specified in tables 10. 1.-2 and 10.1-3 in 3GPP TS 38.213 version 17.7.0 Release 17.

[0022] The NR standard allows for multiple search space configurations in the same slot where a search space configuration includes (among many other things):1. The number of candidates to generate for each aggregation level2. The frequency domain resources where candidates may be generated3. The duration of the search space in number of symbols4. The start symbol of the search space5. The DCI messages which the UE can expect to receive in the search space

[0023] The above information is communicated to the UE using the SearchSpace and ControlResourceSet information elements defined in 5G; NR; Radio Resource Control (RRC); Protocol specification (3GPP TS 38.331 version 17.6.0 Release 17).

[0024] This flexibility allows the network to configure the UE with additional search spaces to meet capacity demand, for example by configuring a UE to listen for the PDCCH in the second symbol instead of or in addition to the first symbol. This allows the network to balance the need for PDCCH with the data rate of PDSCH (since symbols used for PDCCH are taken from PDSCH).

[0025] The constraints described above may be required to be fulfilled for the total of all search space sets in a single slot though.

[0026] Search space types

[0027] It is possible to configure a search space to be a so-called Common Search Space (CSS). Common search spaces do not use the above described (pseudo) randomization algorithm so that candidates will always be in the same place in every slot regardless of the UE identity. The other type of search space is called UE-specific Search Space (USS).

[0028] CSSs are less interesting from a capacity point of view compared to USSs since the intensity of broadcast messages is generally very low compared to the intensity of UE specific messages. However, the constraints on number of blind decode attempts and nonoverlapping CCEs are counted for all search spaces configured for a UE, including the common ones.

[0029] The CSS to assume when connecting to a cell is sent out in system information (which for obvious reasons does not require PDCCH to detect).SUMMARY

[0030] There currently exist certain challenge(s).

[0031] The PDCCH is very often a capacity bottleneck in NR systems due to most traffic consisting of small packets. This means that a typical high loaded cell has a very large number of users where the large majority needs to transmit very little data.

[0032] Adding more symbols to the PDCCH (by configuring more search spaces) is a natural way to handle the above typical high loaded cell. However, the non-overlapping CCE constraint becomes severe at high bandwidths since it limits how many candidates each UE can listen to. An indication of this can be seen comparing Figure 3a and Figure 3b.

[0033] Figure 3a illustrates example of a PDCCH search space set using a configuration with a search space in only symbol 0. The total number of non-overlapping CCEs in this case is 31 (other slot number and / or UE IDs will result in different numbers).

[0034] Figure 3b illustrates example of a PDCCH search space set using a configuration with a search space in symbol 0 and another search space in symbol 1. The total number of nonoverlapping CCEs in this case is 31 (other slot number and / or UE IDs will result in different numbers).

[0035] Despite both having the same number of non-overlapping CCEs the configuration in Figure 3b has fewer candidates in total compared to Figure 3a.

[0036] One known way to mitigate the non-overlapping constraint is to take advantage of the standards capability to configure each UE individually.

[0037] This can be used to have UEs in poor radio have more high AL (e.g. AL16 and / or AL8) candidates and fewer (or zero) low AL (e.g. AL1 and / or AL2) candidates and vice versa for UEs in good radio. This has the drawback that it requires RRC signaling to change the search space configuration when the radio conditions change which takes long time and has an increased risk of losing connection to the UE.

[0038] Another way to mitigate the non-overlapping constraint is to have different configurations for different UEs, so that some UEs have (more) candidates in the first symbol, some have (more) candidates in the second symbol etc.

[0039] Figure 4a illustrates an example in which a UE 20955 has two search spaces configurations, one in symbol 0 which has more candidates than the search space configuration in symbol 1. Figure 4b illustrates an example in which a UE 4402 has twosearch space configuration, one in symbol 0 which has less candidates than the search space configuration in symbol 1.

[0040] The disadvantage of this is that a UE which has its PDCCH in symbol n that UE can’t use symbols before n for the PDSCH (and can only use symbol n for PDSCH if the PDSCH allocation does not overlap any other UEs PDCCH allocation). As the UEs come and go there will inevitably be UEs which have a lot of data which end up having their search space configured so that they can only be allocated PDCCH in a symbol > 0 and therefore system resources are wasted whenever such users are scheduled since symbols before the users PDCCH can’t (effectively) be used for anything. This again would require that the network reconfigures the UEs over RRC and the functionality to effectively figure when and how to reconfigure is not trivial to design.

[0041] A similar idea how to handle the non-overlapping constraint is to use a smaller part of the frequency for each UE and configure different UEs to listen to different parts. For example, if the number of CCEs in the CCE pool is limited to 16 then the maximum number of non-overlapping CCEs can naturally never be larger than 16 in a single symbol. This allows for adding more search spaces in other symbols without hitting the non-overlapping CCE limit. This has a somewhat similar drawback as the above as the system will eventually end up in a state where the parts of the frequency the active UEs listen to is imbalanced. Resolving this requires RRC reconfiguration as well as non-trivial functionality to determine how and when to reconfigure.

[0042] Certain aspects of the disclosure and their embodiments may provide solutions to these or other challenges.

[0043] In particular, embodiments described herein improve the capacity of the PDCCH. Often the PDCCH suffers where 1000 UEs have data to be sent, and so lots of UEs need to be scheduled, and there isn’t capacity in the current search space configurations to schedule all the UEs - without encountering blocking issues. The UEs are effectively competing over the same CCEs.

[0044] According to some embodiments there is therefore provided a method performed by a network node in a communications network for configuring a user equipment, UE, with a physical downlink control channel, PDCCH, search space. The method comprises transmitting a reduced aggregation level, AL, search space configuration to the UE, wherein the reduced AL search space configuration comprises only candidate sets ofControl Channel Elements, CCEs, in ALs that are lower than a maximum aggregation level available in a communications network.

[0045] A method performed by a user equipment in a communications network for enabling configuration of a Physical Downlink Control Channel, PDCCH search space. The method comprises receiving, from a network node, a reduced aggregation level, AL, search space configuration, wherein the reduced AL search space configuration comprises only candidate sets of Control Channel Elements, CCEs, in ALs that are lower than a maximum AL available in a communications network.

[0046] A network node in a communications network for configuring a user equipment, UE, with a physical downlink control channel, PDCCH, search space. The network node comprises processing circuitry and memory, the memory containing instructions executable by the processing circuitry whereby the network node is operable to: transmit a reduced aggregation level, AL, search space configuration to the UE, wherein the reduced AL search space configuration comprises only candidate sets of Control Channel Elements, CCEs, in ALs that are lower than a maximum aggregation level available in a communications network.

[0047] A user equipment in a communications network for enabling configuration of a Physical Downlink Control Channel, PDCCH search space. The user equipment comprises processing circuitry and memory, the memory containing instructions executable by the processing circuitry whereby the user equipment is operable to: receive, from a network node, a reduced aggregation level, AL, search space configuration, wherein the reduced AL search space configuration comprises only candidate sets of Control Channel Elements, CCEs, in ALs that are lower than a maximum AL available in a communications network.

[0048] A computer program, comprising instructions which, when executed on at least one processor, cause the at least one processor to carry out any of the methods described above.

[0049] According to some embodiments there is provided a carrier containing the computer program as described above, wherein the carrier comprises one of an electronic signal, optical signal, radio signal or computer readable storage medium.

[0050] According to some embodiments there is provided a computer-readable medium comprising instructions that, when executed on at least one processor, cause the at least one processor to perform any of the methods described above.

[0051] A computer program product comprising non transitory computer readable media having stored thereon a computer program as described above.

[0052] Certain embodiments may provide one or more of the following technical advantage(s).

[0053] The embodiments described herein provide a distinct advantage over the prior art when it comes to capacity in terms of how many UEs can be scheduled at the same time. It effectively alleviates the PDCCH as a bottleneck for system capacity and thereby improves the time to content and throughput for the end users in cells which have moderate to high load without sacrificing coverage.

[0054] For example, the fact that a single AL4 PDCCH candidate can fulfill the role of an AL4, an AL8 and an AL 16 and therefore does not consume extra non-overlapped CCEs and blind- decode attempts in conjunction with the fact that it is less sensitive to the fragmentation problem (as described below) makes the method perform much better than the prior art as illustrated in Figure 12 and 13 later.BRIEF DESCRIPTION OF THE DRAWINGS

[0055] For a better understanding of the embodiments of the present disclosure, and to show how it may be put into effect, reference will now be made, by way of example only, to the accompanying drawings, in which:

[0056] Fig. 1 illustrates an example of two search space for a UE 20955 in two different slots;

[0057] Fig. 2 illustrates an example of two search space sets for the UE 4402 in two different slots;

[0058] Fig. 3a illustrates example of a PDCCH search space set using a configuration with a search space in only symbol 0;

[0059] Fig. 3b illustrates example of a PDCCH search space set using a configuration with a search space in symbol 0 and another search space in symbol 1;

[0060] Fig. 4a illustrates an example in which a UE 20955 has two search spaces configurations, one in symbol 0 which has more candidates than the search space configuration in symbol i;

[0061] Fig. 4b illustrates an example in which a UE 4402 has two search space configuration, one in symbol 0 which has less candidates than the search space configuration in symbol 1;

[0062] Fig. 5 illustrates an example process for validating a search space configuration offline for all possible UE identities;

[0063] Fig. 6 illustrates is a signalling diagram illustrating radio resource control (RRC) reconfiguration

[0064] Fig. 7 is a flow chart illustrating a method in accordance with some embodiments;

[0065] Fig. 8 illustrates an example of a 2-symbol reduced AL search space configuration which fulfills both the max blind decode attempts and non-overlapping CCE constraints in numerology 1.

[0066] Fig. 9 illustrates an example implementation of step 704

[0067] Fig. 10 illustrates an example implementation of step 704

[0068] Fig. 11 is a flow chart illustrating a method in accordance with some embodiments;

[0069] Fig. 12 illustrates results from a simulation showing in how many slots users were prevented from being scheduled due to lack of PDCCH (y-axis) vs load (x-axis);

[0070] Fig. 13 illustrates results from a simulation showing end user packet delay (y-axis) vs load (x-axis);

[0071] Fig. 14 shows an example of a communication system in accordance with some embodiments;

[0072] Fig. 15 shows a UE in accordance with some embodiments;

[0073] Fig. 16 shows a network node in accordance with some embodiments.DETAILED DESCRIPTION

[0074] From a capacity point of view, it will be appreciated that the goal of the search space configuration is to fit as many PDCCH candidates in the search space without exceeding the number of blind decodes and non-overlapping CCE constraints. The number of blind decodes is simple since it is just a matter of counting the total number of candidates. For the number of non-overlapping CCEs, there is no known closed form expression. Instead, the only way to determine if a potential search space configuration meets the non-overlapping CCE constraint is to try all slots in a frame (10 for numerology 0, 20 for numerology 1 etc.) for the selected UE identity. A very reasonable simplification is to do the validation of a search space configuration offline for all possible UE identities (about 2A16 possibilities in NR) and use that configuration for all UEs. An example of this process is shown in Figure 5. Being able to check whether the non-overlapping CCE constraint is fulfilled is not enough to find good configurations that help to relieve the capacity issue.

[0075] Some of the embodiments contemplated herein will now be described more fully with reference to the accompanying drawings. Embodiments are provided by way of example to convey the scope of the subject matter to those skilled in the art.

[0076] Embodiments described herein may be carried out in two main steps. The first step is the configuration of the PDCCH search spaces. For this the configuration may transmitted tothe UE, for example, in an RRC reconfiguration message as illustrated in step 601 of Figure 6, and is typically performed when the UE first attaches to a cell. The UE may then response to the RRC reconfiguration message with an RRCReconfigurationComplete message as illustrated in step 602 of Figure 6.

[0077] The second step is the selection of which PDCCH candidate to use and what power level to use for the transmission denoted CCE allocation. This step may be performed for every single PDCCH transmission so it naturally occurs at a much higher frequency compared to the search space configuration.

[0078] It can be seen from Figures 1 to 4 that high aggregation levels are more difficult to fit within the search space set than small aggregation levels since they are more easily blocked. For example, when looking at Figure the small ALs tend to fragment the CCE resource so that the larger ones don’t fit even if there are a lot of CCEs still available in total. This is referred to herein as the “fragmentation problem”.

[0079] Traditional techniques may be considered to solve this type of problem such as Boolean satisfiability problem techniques or mixed integer programming are infeasible in practice. The CCE allocation must be performed in each slot due to search spaces randomizing for each slot and the simple fact that which users have data, and how important that data is, changes from slot to slot. Even simple bespoke heuristics such as looking ahead for high AL UEs and avoiding their PDCCH candidates if possible, suffer from the fact that the network is typically very limited in how many UEs and PDCCH candidates it can process in a slot.

[0080] Embodiments described herein therefore make use of this inventive realization that high ALs are the main offender for both the fragmentation problem and the non-overlapping CCEs.Embodiments described herein therefore use search space configurations with only low ALs (e.g. only AL1 , AL2, and AL4) so that the search space can become dense without exceeding the number of non-overlapped CCE constraint. Increased transmit power may then be used to compensate for the loss of coverage. For example, instead of AL8, embodiments described herein may use AL4 and double the transmit power. Similarly Instead of AL 16, embodiments described herein may use AL4 and quadruple the transmit power.

[0081] Figure 7 illustrates a method performed by a network node in a communications network in accordance with particular embodiments. The method may be for configuring a user equipment, UE, with a physical downlink control channel, PDCCH, search space. Themethod of Figure 7 may be performed by a network node (e.g. the network node 1410 or network node 1600 as described later with reference to Figures 14 and 16 respectively). The method may in some examples begin at step 701 with transmitting a reduced aggregation level, AL, search space configuration to the UE, wherein the reduced AL search space configuration comprises only candidate sets of Control Channel Elements, CCEs, in ALs that are lower than a maximum aggregation level available in a communications network.

[0082] Herein the term reduced aggregation level, AL, search space configuration may be utilized to refer to any search space configuration for which at least the maximum aggregation level available in the communications network has not been used to form the candidate sets of CCEs. A maximum aggregation level available in the communications network may be determined or derived or set by the standard by which the network node is operating.

[0083] For example, the reduced AL search space configuration may comprise only candidate sets of Control Channel Elements that are in AL 1 to AL 4 or AL1 to AL 8 (e.g. for NR).

[0084] Step 701 may comprising transmitting the reduced AL search space configuration is transmitted as part of a Radio Resource Control, RRC, message (e.g. the RRCreconfigurationmessage 601 as illustrated in Figure 6).

[0085] Once the network node has configured the UE with the reduced AL search space configuration it may apply different transmit power to achieve different levels of robustness when transmitting a PDCCH transmission utilizing one of the candidate sets of CCEs. Examples of how this may be performed as described later with reference to Figures 9 and 10.

[0086] Figure 8 illustrates an example of a 2-symbol reduced AL search space configuration which fulfills both the max blind decode attempts and non-overlapping CCE constraints where the subcarrier spacing is 30kHz. In particular, Figure 8 illustrates PDCCH search space set using a configuration with a search space in symbol 0 and another search space in symbol 1 where AL8 and AL 16 are replaced by more lower AL candidates.

[0087] However, it will be appreciated that when applying different transmit powers, power boosting may cause harmful interference towards neighboring cells. Therefore in some examples, the method of Figures 7 comprises step 702. Step 702 enables the network node to only apply power boosting when there is really a need for it (to deal with PDCCH blocking issue).

[0088] Step 702 may comprise determining whether a PDCCH blocking level in a cell serving the first UE meets a first threshold condition associated with a first threshold blocking level.

[0089] Step 701 may then be performed responsive to determining that a PDCCH blocking level in a cell serving the first UE meets the first threshold condition associated with a first threshold blocking level.

[0090] For the purpose of determining the PDCCH blocking level, the cell-level counters, PDCCH-blocking-PDSCH-occasions and PDCCH-blocking-PUSCH-occasions, might be considered to evaluate a PDCCH blocking level. It is possible to collect these celllevel counters on different time granularities. Alternatively, cell load (in terms of PRB utilization and the number of RRC-connected users) can be considered, instead of PDCCH blocking or in addition to PDCCH blocking to evaluate the PDCCH blocking level.

[0091] In some examples, the PDCCH blocking may be considered to occur when after resource allocation is performed for a slot the following are true:

[0092] 1. There was at least one UE with data in either uplink or downlink that didn’t get a PDCCH resource

[0093] 2. There was one or more unused shared channel PRBs of the type needed for the UE (i.e., PDSCH for downlink data or PUSCH for uplink data)

[0094] The fraction of slots in which PDCCH blocking occurs can be used as the PDCCH blocking level for a cell.

[0095] In other words, the method of Figure 7 may further comprise determining the PDCCH blocking level based on one or more of: a fraction of time periods (e.g. slots) in a plurality of time periods (e.g. 100-10k slots) in which PDCCH blocking occurs in the cell; and an average amount of unused shared channel PRBs of a type needed by the UE across a plurality of time periods in the cell.

[0096] In some examples PDCCH blocking may be considered to occur when there was shared channel of the type needed for the UE or there was another UE with lower priority which got shared channel of the type needed for the UE (i.e., PDSCH for downlink data or PUSCH for uplink data). When this definition of PDCCH blocking is applied, one may also count the shared channel PRBs given to the lower priority UEs towards the blocking level (since this is resources which could have been given to the higher priority UE if it was not blocked from getting PDCCH resources).

[0097] In some examples, the first threshold condition of step 702 comprises a condition that the PDCCH blocking level is > a first threshold level.

[0098] If, in step 702 it is determined that the PDCCH blocking level does not meet the first threshold condition, the method may pass to step 703 which comprises transmitting a normal search space configuration to the UE. A normal search space configuration may be a search space configuration that utilizes all available AL levels in the communications network. In this example, the network node may not apply power boosting when transmitting PDCCH transmissions to the UE utilizing the candidate sets of CCEs in the normal search space configuration.

[0099] In some examples, further granularity may be applied to define the ALs included within a reduced AL search space configuration.11001 For example, in some examples step 701 may comprise step 701a. Step 701a comprises determining whether the PDCCH blocking level meets a second threshold condition. The second threshold condition may be that the PDCCH blocking level is less than a second threshold level.HOU If the PDCCH block level meets the first threshold condition associated with the first threshold blocking level and a meets the second threshold condition associated with a second threshold blocking level, the method passes to step 701b in which the reduced AL search space configuration (transmitted in step 701) comprises only candidate sets of Control Channel Elements, CCEs, in ALs that are lower than at least a highest Y aggregation levels available in a communications network, where Y is greater than or equal to 1. For example, Y may be equal to 1. For example, if the network node were to consider that AL 16 is suitable, the network node may select an AL 8 candidate and may utilize 3 dB power boosting instead of utilizing AL 16.11021 If the PDCCH blocking level meets the first threshold condition associated with the first threshold blocking level but does not meet the second threshold condition associated with a second threshold blocking level, the method passes to step 701c in which the reduced AL search space configuration (transmitted in step 701) comprises only candidate sets of Control Channel Elements, CCEs, in ALs that are lower than at least a highest Z aggregation levels, where Z > Y available in a communications network. For example, Z may be equal to 2. In this example, the network node may use CCE-AL 4 with 6 dB power boosting and use CCE-AL 4 with 3 dB power boosting, respectively, instead of CCE-AL 16 and CCE- AL 8.11031 It will be appreciated that any number of threshold conditions may be introduced in order to control the configuration of the reduced AL search space configuration.11041 For example, a third threshold condition may be whether the PDCCH blocking level is greater than a third threshold level. If this condition is met the reduced AL search space configuration may comprise only candidate sets of CCEs in ALs that are lower than at least a highest W, where W>Z, ALs available in the communication network. For example, W may be equal to 3. In this example, the network node may use CCEs in AL 2 with 6 dB power boosting and use CCEs in AL 2 with 3 dB power boosting and CCEs in AL 4 with 6 dB power boosting, respectively, instead of CCE-AL 8 and CCE-AL 4 and CCE-AL16.11051 In some embodiments, the method of Figure 7 may then further comprise step 704 in which the network node transmits a PDCCH transmission to the UE utilizing one of the candidate sets of CCEs in the reduced aggregation level, AL, search space configuration. In some examples, the transmission of the PDCCH to the UE is performed with some power boosting, for example, to account for the reduced AL search space configuration.11O CCE allocation is performed for each individual PDCCH transmission to be performed by the network. CCE allocation may be broken down into the following two steps:1. Determining which AL and power is required such that the transmission has an acceptable probability of being successfully decoded in the UE2. Out of the PDCCH candidates in the search space set of an individual UE, which ones shall be allocated to minimize the fragmentation problem.11071 For example, step 704 may be performed as described with reference to Figure 9.11081 In step 901 the method comprises estimating a downlink SINR, SINR_est, associated with the UE. The downlink SINR estimate may be estimated from CSI reports, HARQ feedback and uplink reference signals (in case reciprocity can be assumed). The method of Figure 9 may therefore further comprise determining the downlink SINR from one or more of: channel state information reports from the UE, HARQ feedback from the UE, and uplink reference signals received from the UE.11091 In step 902 the method comprises mapping the SINR_est to a first AL, wherein the first AL is included in the reduced AL search space configuration. The mapping may be derived by utilizing simulation results or lab test results to map an SINR to a lowest AL which has an acceptable error probability.Hioi In step 903 the method comprises determining a first transmit power based on a nominal transmit power assumed for SINR est and a minimum downlink SINR, SINR AL s, for which the first AL has minimum threshold probability for successful reception at the UE.For example, the first transmit power may be determined as the maximum of 1 or SINR_AL_s / SINR_est times the nominal transmit power.Hill In step 904 the method then comprises transmitting a PDCCH transmission utilizing a candidate set of CCEs in the first AL at the first transmit power.H121 In another example, step 704 may be performed as described with reference to Figure 10.H131 In step 1001 the method comprises determining that a PDCCH transmission to the UE should be made utilizing a first AL based on a mapping that maps the first AL to a downlink channel quality associated with the UE, wherein the first AL is not included in the reduced AL search space configuration. The mapping may be derived by utilizing simulation results or lab test results to map a downlink channel quality to a lowest AL which has an acceptable error probability. The downlink channel quality may be estimated from CSI reports, HARQ feedback and uplink reference signals (in case reciprocity can be assumed). The method of Figure 10 may therefore further comprise determining the downlink channel quality from one or more of: channel state information reports from the UE, HARQ feedback from the UE, and uplink reference signals received from the UE.

[0114] Step 1002 comprises responsive to step 1001, transmitting, with a second transmit power that is higher than the first transmit power, the PDCCH transmission utilizing a second AL that is included in the reduced AL search space configuration.H151 In some examples, the first AL comprises AL N and the second AL comprises AL N / M, where N is an integer number and M is another integer number, and wherein the first transmit power comprises X W and the second transmit power comprises M*X W.H161 For example, if the first AL is AL 8, then the second AL may be AL4 and the second transmit power may be boosted by a factor 2 compared to the first transmit power. If the first AL is AL 16, then the second AL may be AL4 and the second transmit power may be boosted by a factor of 4 compared to the first transmit power. Here the first transmit power may be a nominal power that is assumed when making the downlink channel quality estimate / measurement.11121 For Step 2 of the CCE allocation above it is noted that since the high ALs are replaced by higher transmit power, simple schemes such as greedy heuristics may work better with the embodiments described herein since the transmit power can be divided between users freely.

[0118] Figure 11 depicts a method in accordance with particular embodiments. The method of Figure 11 may be performed by a UE or wireless device (e.g. the UE 1412 or UE 1500 as described later with reference to Figures 14 and 15 respectively). The method may be performed for for enabling configuration of a Physical Downlink Control Channel, PDCCH search space. The method begins at step 1102 with receiving, from a network node, a reduced aggregation level, AL, search space configuration, wherein the reduced AL search space configuration comprises only candidate sets of Control Channel Elements, CCEs, in ALs that are lower than a maximum AL available in a communications network. For example, the reduced AL search space configuration may comprise only candidate sets of Control Channel Elements that are in AL 1 to AL 4 or only in AL1 to AL8. The reduced AL search space configuration may be transmitted as part of a Radio Resource Control, RRC, message.EXPERIMENTAL RESULTSH191 To determine if the invention has any significant advantage over the prior art, system simulations have been performed in a dynamic system simulator. The traffic model used has been fitted from packet level data from a high loaded site in a real network. 100 MHz TDD using numerology 1 was used.11201 The following options were simulated:• 1 Symbol- Symbol 1 SS: {5, 4, 3, 2, 2}• 2 Symbol- Symbol 1 SS: {4, 2, 1,1,1}- Symbol 2 SS: {4,1, 1,0,0}• 2 Symbol pb (power boost)- Symbol 1 SS: {4, 2, 3, 0,0}- Symbol 2 SS: {2, 2, 3, 0,0}- Agg level 4 may use lx, 2x or 4x nominal power (all other agg levels may only use lx)• 2 Symbol pc (power control)- Symbol 1 SS: {4, 2, 3, 0,0}- Symbol 2 SS: {2, 2, 3, 0,0}- Agg level 1 may use 0.25x, 0.5x or lx nominal power and agg levels 2 and 4 have a fine-grained set of allowed power levels• 2 Symbols magic- Symbol 1 SS: {4, 2, 1,1,1}- Symbol 2 SS: {45,23,12,6,3}11211 The notation SS: {A,B,C,D,E} means A AL1 candidates, B AL2 candidates, and so on, are provided in the search space.11221 The options called “1 Symbol” and “2 Symbol” are from the prior art. The options called “2 Symbol pb” and “2 Symbol pc” represent different embodiments of the invention. The option “2 Symbols magic” represents an unrealistic upper bound where the search space constraints are removed.

[0123] Figure 12 illustrates the results from the simulation showing in how many slots at least one user was prevented from being scheduled due to lack of PDCCH (y-axis) vs load (x- axis).H2 Both averages (mean) and 95 -percentiles (p95) are shown.

[0125] Figure 13 illustrates results from the simulation showing end user packet delay (y-axis) vs load (x-axis). Both averages (mean) and 95 -percentiles (p95) are shown.

[0126] Figures 12 and 13 illustrate that adding one extra symbol in the prior art has a net negative since the search space becomes sparser due to the non-overlapping CCE constraint. On the other hand, utilizing the embodiments described herein shows almost as good performance as the theoretical upper bound where constraints for blind-decode attempts and nonoverlapping CCEs are removed.

[0127] Figure 14 shows an example of a communication system 1400 in accordance with some embodiments.11281 In the example, the communication system 1400 includes a telecommunication network 1402 that includes an access network 1404, such as a radio access network (RAN), and a core network 1406, which includes one or more core network nodes 1408. The access network 1404 includes one or more access network nodes, such as network nodes 1410a and 1410b (one or more of which may be generally referred to as network nodes 1410), or any other similar 3rdGeneration Partnership Project (3GPP) access nodes or non-3GPP access points. Moreover, as will be appreciated by those of skill in the art, a network node is not necessarily limited to an implementation in which a radio portion and a baseband portion are supplied and integrated by a single vendor. Thus, it will be understood that network nodes include disaggregated implementations or portions thereof. For example, in some embodiments, the telecommunication network 1402 includes one or more Open-RAN(ORAN) network nodes. An ORAN network node is a node in the telecommunication network 1402 that supports an ORAN specification (e.g., a specification published by the O-RAN Alliance, or any similar organization) and may operate alone or together with other nodes to implement one or more functionalities of any node in the telecommunication network 1402, including one or more network nodes 1410 and / or core network nodes 1408.

[0129] Examples of an ORAN network node include an open radio unit (O-RU), an open distributed unit (O-DU), an open central unit (O-CU), including an O-CU control plane (O- CU-CP) or an O-CU user plane (O-CU-UP), a RAN intelligent controller (near-real time or non-real time) hosting software or software plug-ins, such as a near-real time control application (e.g., xApp) or a non-real time control application (e.g., rApp), or any combination thereof (the adjective “open” designating support of an ORAN specification). The network node may support a specification by, for example, supporting an interface defined by the ORAN specification, such as an Al, Fl, Wl, El, E2, X2, Xn interface, an open fronthaul user plane interface, or an open fronthaul management plane interface. Moreover, an ORAN access node may be a logical node in a physical node. Furthermore, an ORAN network node may be implemented in a virtualization environment (described further below) in which one or more network functions are virtualized. For example, the virtualization environment may include an O-Cloud computing platform orchestrated by a Service Management and Orchestration Framework via an 0-2 interface defined by the O- RAN Alliance or comparable technologies. The network nodes 1410 facilitate direct or indirect connection of user equipment (UE), such as by connecting UEs 1412a, 1412b, 1412c, and 1412d (one or more of which may be generally referred to as UEs 1412) to the core network 1406 over one or more wireless connections.

[0130] Example wireless communications over a wireless connection include transmitting and / or receiving wireless signals using electromagnetic waves, radio waves, infrared waves, and / or other types of signals suitable for conveying information without the use of wires, cables, or other material conductors. Moreover, in different embodiments, the communication system 1400 may include any number of wired or wireless networks, network nodes, UEs, and / or any other components or systems that may facilitate or participate in the communication of data and / or signals whether via wired or wireless connections. The communication system 1400 may include and / or interface with any type of communication, telecommunication, data, cellular, radio network, and / or other similar type of system.11311 The UEs 1412 may be any of a wide variety of communication devices, including wireless devices arranged, configured, and / or operable to communicate wirelessly with the network nodes 1410 and other communication devices. Similarly, the network nodes 1410 are arranged, capable, configured, and / or operable to communicate directly or indirectly with the UEs 1412 and / or with other network nodes or equipment in the telecommunication network 1402 to enable and / or provide network access, such as wireless network access, and / or to perform other functions, such as administration in the telecommunication network 1402.1132} In the depicted example, the core network 1406 connects the network nodes 1410 to one or more hosts, such as host 1416. These connections may be direct or indirect via one or more intermediary networks or devices. In other examples, network nodes may be directly coupled to hosts. The core network 1406 includes one more core network nodes (e.g., core network node 1408) that are structured with hardware and software components. Features of these components may be substantially similar to those described with respect to the UEs, network nodes, and / or hosts, such that the descriptions thereof are generally applicable to the corresponding components of the core network node 1408. Example core network nodes include functions of one or more of a Mobile Switching Center (MSC), Mobility Management Entity (MME), Home Subscriber Server (HSS), Access and Mobility Management Function (AMF), Session Management Function (SMF), Authentication Server Function (AUSF), Subscription Identifier De-concealing function (SIDF), Unified Data Management (UDM), Security Edge Protection Proxy (SEPP), Network Exposure Function (NEF), and / or a User Plane Function (UPF).11331 The host 1416 may be under the ownership or control of a service provider other than an operator or provider of the access network 1404 and / or the telecommunication network 1402, and may be operated by the service provider or on behalf of the service provider. The host 1416 may host a variety of applications to provide one or more services. Examples of such applications include the provision of live and / or pre-recorded audio / video content, data collection services, for example, retrieving and compiling data on various ambient conditions detected by a plurality of UEs, analytics functionality, social media, functions for controlling or otherwise interacting with remote devices, functions for an alarm and surveillance center, or any other such function performed by a server.11341 As a whole, the communication system 1400 of Figure 14 enables connectivity between the UEs, network nodes, and hosts. In that sense, the communication system may beconfigured to operate according to predefined rules or procedures, such as specific standards that include, but are not limited to: Global System for Mobile Communications (GSM); Universal Mobile Telecommunications System (UMTS); Long Term Evolution (LTE), and / or other suitable 2G, 3G, 4G, 5G standards, or any applicable future generation standard (e.g., 6G); wireless local area network (WLAN) standards, such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards (WiFi); and / or any other appropriate wireless communication standard, such as the Worldwide Interoperability for Microwave Access (WiMax), Bluetooth, Z-Wave, Near Field Communication (NFC) ZigBee, LiFi, and / or any low-power wide-area network (LPWAN) standards such as LoRa and Sigfox.11351 In some examples, the telecommunication network 1402 is a cellular network that implements 3GPP standardized features. Accordingly, the telecommunications network 1402 may support network slicing to provide different logical networks to different devices that are connected to the telecommunication network 1402. For example, the telecommunications network 1402 may provide Ultra Reliable Low Latency Communication (URLLC) services to some UEs, while providing Enhanced Mobile Broadband (eMBB) services to other UEs, and / or Massive Machine Type Communication (mMTC) / Massive loT services to yet further UEs.11361 In some examples, the UEs 1412 are configured to transmit and / or receive information without direct human interaction. For instance, a UE may be designed to transmit information to the access network 1404 on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the access network 1404. Additionally, a UE may be configured for operating in single- or multi-RAT or multistandard mode. For example, a UE may operate with any one or combination of Wi-Fi, NR (New Radio) and LTE, i.e. being configured for multi-radio dual connectivity (MR-DC), such as E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network) New Radio - Dual Connectivity (EN-DC).11371 In the example illustrated in Figure 14, the hub 1414 communicates with the access network 1404 to facilitate indirect communication between one or more UEs (e.g., UE 1412c and / or 1412d) and network nodes (e.g., network node 1410b). In some examples, the hub 1414 may be a controller, router, a content source and analytics node, or any of the other communication devices described herein regarding UEs. For example, the hub 1414 may be a broadband router enabling access to the core network 1406 for the UEs. As another example, the hub 1414 may be a controller that sends commands or instructions to one ormore actuators in the UEs. Commands or instructions may be received from the UEs, network nodes 1410, or by executable code, script, process, or other instructions in the hub 1414. As another example, the hub 1414 may be a data collector that acts as temporary storage for UE data and, in some embodiments, may perform analysis or other processing of the data. As another example, the hub 1414 may be a content source. For example, for a UE that is a VR headset, display, loudspeaker or other media delivery device, the hub 1414 may retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, which the hub 1414 then provides to the UE either directly, after performing local processing, and / or after adding additional local content. In still another example, the hub 1414 acts as a proxy server or orchestrator for the UEs, in particular if one or more of the UEs are low energy loT devices.11381 The hub 1414 may have a constant / persistent or intermittent connection to the network node 1410b. The hub 1414 may also allow for a different communication scheme and / or schedule between the hub 1414 and UEs (e.g., UE 1412c and / or 1412d), and between the hub 1414 and the core network 1406. In other examples, the hub 1414 is connected to the core network 1406 and / or one or more UEs via a wired connection. Moreover, the hub 1414 may be configured to connect to an M2M service provider over the access network 1404 and / or to another UE over a direct connection. In some scenarios, UEs may establish a wireless connection with the network nodes 1410 while still connected via the hub 1414 via a wired or wireless connection. In some embodiments, the hub 1414 may be a dedicated hub- that is, a hub whose primary function is to route communications to / from the UEs from / to the network node 1410b. In other embodiments, the hub 1414 may be a non-dedicated hub- that is, a device which is capable of operating to route communications between the UEs and network node 1410b, but which is additionally capable of operating as a communication start and / or end point for certain data channels.

[0139] Figure 15 shows a UE 1500 in accordance with some embodiments. As used herein, a UE refers to a device capable, configured, arranged and / or operable to communicate wirelessly with network nodes and / or other UEs. Examples of a UE include, but are not limited to, a smart phone, mobile phone, cell phone, voice over IP (VoIP) phone, wireless local loop phone, desktop computer, personal digital assistant (PDA), wireless camera, gaming console or device, music storage device, playback appliance, wearable terminal device, wireless endpoint, mobile station, tablet, laptop, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), smart device, wireless customer-premise equipment(CPE), vehicle, vehicle-mounted or vehicle embedded / integrated wireless device, etc. Other examples include any UE identified by the 3rd Generation Partnership Project (3GPP), including a narrow band internet of things (NB-IoT) UE, a machine type communication (MTC) UE, and / or an enhanced MTC (eMTC) UE.11401 A UE may support device-to-device (D2D) communication, for example by implementing a 3GPP standard for sidelink communication, Dedicated Short-Range Communication (DSRC), vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), or vehicle-to-everything (V2X). In other examples, a UE may not necessarily have a user in the sense of a human user who owns and / or operates the relevant device. Instead, a UE may represent a device that is intended for sale to, or operation by, a human user but which may not, or which may not initially, be associated with a specific human user (e.g., a smart sprinkler controller). Alternatively, a UE may represent a device that is not intended for sale to, or operation by, an end user but which may be associated with or operated for the benefit of a user (e.g., a smart power meter).11411 The UE 1500 includes processing circuitry 1502 that is operatively coupled via a bus 1504 to an input / output interface 1506, a power source 1508, a memory 1510, a communication interface 1512, and / or any other component, or any combination thereof. Certain UEs may utilize all or a subset of the components shown in Figure 15. The level of integration between the components may vary from one UE to another UE. Further, certain UEs may contain multiple instances of a component, such as multiple processors, memories, transceivers, transmitters, receivers, etc.11421 The processing circuitry 1502 is configured to process instructions and data and may be configured to implement any sequential state machine operative to execute instructions stored as machine-readable computer programs in the memory 1510. The processing circuitry 1502 may be implemented as one or more hardware-implemented state machines (e.g., in discrete logic, field-programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), etc.); programmable logic together with appropriate firmware; one or more stored computer programs, general-purpose processors, such as a microprocessor or digital signal processor (DSP), together with appropriate software; or any combination of the above. For example, the processing circuitry 1502 may include multiple central processing units (CPUs). The processing circuitry 1502 may be operable to provide, either alone or in conjunction with other UE 1500 components, such as the memory 1510,UE 1500 functionality. For example, the processing circuitry 1502 may be configured to cause the UE 1502 to perform the methods as described with reference to Figure 11.11431 In the example, the input / output interface 1506 may be configured to provide an interface or interfaces to an input device, output device, or one or more input and / or output devices. Examples of an output device include a speaker, a sound card, a video card, a display, a monitor, a printer, an actuator, an emitter, a smartcard, another output device, or any combination thereof. An input device may allow a user to capture information into the UE 1500. Examples of an input device include a touch-sensitive or presence-sensitive display, a camera (e.g., a digital camera, a digital video camera, a web camera, etc.), a microphone, a sensor, a mouse, a trackball, a directional pad, a trackpad, a scroll wheel, a smartcard, and the like. The presence-sensitive display may include a capacitive or resistive touch sensor to sense input from a user. A sensor may be, for instance, an accelerometer, a gyroscope, a tilt sensor, a force sensor, a magnetometer, an optical sensor, a proximity sensor, a biometric sensor, etc. , or any combination thereof. An output device may use the same type of interface port as an input device. For example, a Universal Serial Bus (USB) port may be used to provide an input device and an output device.11441 In some embodiments, the power source 1508 is structured as a battery or battery pack. Other types of power sources, such as an external power source (e.g., an electricity outlet), photovoltaic device, or power cell, may be used. The power source 1508 may further include power circuitry for delivering power from the power source 1508 itself, and / or an external power source, to the various parts of the UE 1500 via input circuitry or an interface such as an electrical power cable. Delivering power may be, for example, for charging of the power source 1508. Power circuitry may perform any formatting, converting, or other modification to the power from the power source 1508 to make the power suitable for the respective components of the UE 1500 to which power is supplied.11451 The memory 1510 may be or be configured to include memory such as random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), magnetic disks, optical disks, hard disks, removable cartridges, flash drives, and so forth. In one example, the memory 1510 includes one or more application programs 1514, such as an operating system, web browser application, a widget, gadget engine, or other application, and corresponding data 1516. The memory 1510may store, for use by the UE 1500, any of a variety of various operating systems or combinations of operating systems.11461 The memory 1510 may be configured to include a number of physical drive units, such as redundant array of independent disks (RAID), flash memory, USB flash drive, external hard disk drive, thumb drive, pen drive, key drive, high-density digital versatile disc (HD- DVD) optical disc drive, internal hard disk drive, Blu-Ray optical disc drive, holographic digital data storage (HDDS) optical disc drive, external mini-dual in-line memory module (DIMM), synchronous dynamic random access memory (SDRAM), external micro-DIMM SDRAM, smartcard memory such as tamper resistant module in the form of a universal integrated circuit card (UICC) including one or more subscriber identity modules (SIMs), such as a USIM and / or ISIM, other memory, or any combination thereof. The UICC may for example be an embedded UICC (eUICC), integrated UICC (iUICC) or a removable UICC commonly known as ‘SIM card.’ The memory 1510 may allow the UE 1500 to access instructions, application programs and the like, stored on transitory or non-transitory memory media, to off-load data, or to upload data. An article of manufacture, such as one utilizing a communication system may be tangibly embodied as or in the memory 1510, which may be or comprise a device-readable storage medium.11471 The processing circuitry 1502 may be configured to communicate with an access network or other network using the communication interface 1512. The communication interface 1512 may comprise one or more communication subsystems and may include or be communicatively coupled to an antenna 1522. The communication interface 1512 may include one or more transceivers used to communicate, such as by communicating with one or more remote transceivers of another device capable of wireless communication (e.g., another UE or a network node in an access network). Each transceiver may include a transmitter 1518 and / or a receiver 1520 appropriate to provide network communications (e.g., optical, electrical, frequency allocations, and so forth). Moreover, the transmitter 1518 and receiver 1520 may be coupled to one or more antennas (e.g., antenna 1522) and may share circuit components, software or firmware, or alternatively be implemented separately.11481 In some embodiments, communication functions of the communication interface 1512 may include cellular communication, Wi-Fi communication, LPWAN communication, data communication, voice communication, multimedia communication, short-range communications such as Bluetooth, near-field communication, location-based communication such as the use of the global positioning system (GPS) to determine alocation, another like communication function, or any combination thereof. Communications may be implemented in according to one or more communication protocols and / or standards, such as IEEE 802.11, Code Division Multiplexing Access (CDMA), Wideband Code Division Multiple Access (WCDMA), GSM, LTE, New Radio (NR), UMTS, WiMax, Ethernet, transmission control protocol / intemet protocol (TCP / IP), synchronous optical networking (SONET), Asynchronous Transfer Mode (ATM), QUIC, Hypertext Transfer Protocol (HTTP), and so forth.11491 Regardless of the type of sensor, a UE may provide an output of data captured by its sensors, through its communication interface 1512, via a wireless connection to a network node. Data captured by sensors of a UE can be communicated through a wireless connection to a network node via another UE. The output may be periodic (e.g., once every 15 minutes if it reports the sensed temperature), random (e.g., to even out the load from reporting from several sensors), in response to a triggering event (e.g., when moisture is detected an alert is sent), in response to a request (e.g., a user initiated request), or a continuous stream (e.g., a live video feed of a patient).11501 As another example, a UE comprises an actuator, a motor, or a switch, related to a communication interface configured to receive wireless input from a network node via a wireless connection. In response to the received wireless input the states of the actuator, the motor, or the switch may change. For example, the UE may comprise a motor that adjusts the control surfaces or rotors of a drone in flight according to the received input or controls a robotic arm performing a medical procedure according to the received input.11511 A UE, when in the form of an Internet of Things (loT) device, may be a device for use in one or more application domains, these domains comprising, but not limited to, city wearable technology, extended industrial application and healthcare. Non-limiting examples of such an loT device are devices which are or which are embedded in: a connected refrigerator or freezer, a TV, a connected lighting device, an electricity meter, a robot vacuum cleaner, a voice controlled smart speaker, a home security camera, a motion detector, a thermostat, a smoke detector, a door / window sensor, a flood / moisture sensor, an electrical door lock, a connected doorbell, an air conditioning system like a heat pump, an autonomous vehicle, a surveillance system, a weather monitoring device, a vehicle parking monitoring device, an electric vehicle charging station, a smart watch, a fitness tracker, a head-mounted display for Augmented Reality (AR) or Virtual Reality (VR), a wearable for tactile augmentation or sensory enhancement, a water sprinkler, an animal- or item-trackingdevice, a sensor for monitoring a plant or animal, an industrial robot, an Unmanned Aerial Vehicle (UAV), and any kind of medical device, like a heart rate monitor or a remote controlled surgical robot. A UE in the form of an loT device comprises circuitry and / or software in dependence on the intended application of the loT device in addition to other components as described in relation to the UE 1500 shown in Figure 15.11521 As yet another specific example, in an loT scenario, a UE may represent a machine or other device that performs monitoring and / or measurements, and transmits the results of such monitoring and / or measurements to another UE and / or a network node. The UE may in this case be an M2M device, which may in a 3GPP context be referred to as an MTC device. As one particular example, the UE may implement the 3GPP NB-IoT standard. In other scenarios, a UE may represent a vehicle, such as a car, a bus, a truck, a ship and an airplane, or other equipment that is capable of monitoring and / or reporting on its operational status or other functions associated with its operation.11531 In practice, any number of UEs may be used together with respect to a single use case. For example, a first UE might be or be integrated in a drone and provide the drone’s speed information (obtained through a speed sensor) to a second UE that is a remote controller operating the drone. When the user makes changes from the remote controller, the first UE may adjust the throttle on the drone (e.g. by controlling an actuator) to increase or decrease the drone’s speed. The first and / or the second UE can also include more than one of the functionalities described above. For example, a UE might comprise the sensor and the actuator, and handle communication of data for both the speed sensor and the actuators.

[0154] Figure 16 shows a network node 1600 in accordance with some embodiments. As used herein, network node refers to equipment capable, configured, arranged and / or operable to communicate directly or indirectly with a UE and / or with other network nodes or equipment, in a telecommunication network. Examples of network nodes include, but are not limited to, access points (APs) (e.g., radio access points), base stations (BSs) (e.g., radio base stations, Node Bs, evolved Node Bs (eNBs) and NR NodeBs (gNBs)), O-RAN nodes or components of an O-RAN node (e.g., O-RU, O-DU, O-CU).11551 Base stations may be categorized based on the amount of coverage they provide (or, stated differently, their transmit power level) and so, depending on the provided amount of coverage, may be referred to as femto base stations, pico base stations, micro base stations, or macro base stations. A base station may be a relay node or a relay donor node controlling a relay. A network node may also include one or more (or all) parts of a distributed radiobase station such as centralized digital units, distributed units (e.g., in an O-RAN access node) and / or remote radio units (RRUs), sometimes referred to as Remote Radio Heads (RRHs). Such remote radio units may or may not be integrated with an antenna as an antenna integrated radio. Parts of a distributed radio base station may also be referred to as nodes in a distributed antenna system (DAS).H5 Other examples of network nodes include multiple transmission point (multi-TRP) 5G access nodes, multi-standard radio (MSR) equipment such as MSR BSs, network controllers such as radio network controllers (RNCs) or base station controllers (BSCs), base transceiver stations (BTSs), transmission points, transmission nodes, multi-cell / multicast coordination entities (MCEs), Operation and Maintenance (O&M) nodes, Operations Support System (OSS) nodes, Self-Organizing Network (SON) nodes, positioning nodes (e.g., Evolved Serving Mobile Location Centers (E-SMLCs)), and / or Minimization of Drive Tests (MDTs).11571 The network node 1600 includes processing circuitry 1602, a memory 1604, a communication interface 1606, and a power source 1608, and / or any other component, or any combination thereof. The network node 1600 may be composed of multiple physically separate components (e.g., a NodeB component and a RNC component, or a BTS component and a BSC component, etc.), which may each have their own respective components. In certain scenarios in which the network node 1600 comprises multiple separate components (e.g., BTS and BSC components), one or more of the separate components may be shared among several network nodes. For example, a single RNC may control multiple NodeBs. In such a scenario, each unique NodeB and RNC pair, may in some instances be considered a single separate network node. In some embodiments, the network node 1600 may be configured to support multiple radio access technologies (RATs). In such embodiments, some components may be duplicated (e.g., separate memory 1604 for different RATs) and some components may be reused (e.g., a same antenna 1610 may be shared by different RATs). The network node 1600 may also include multiple sets of the various illustrated components for different wireless technologies integrated into network node 1600, for example GSM, WCDMA, LTE, NR, WiFi, Zigbee, Z-wave, LoRaWAN, Radio Frequency Identification (RFID) or Bluetooth wireless technologies. These wireless technologies may be integrated into the same or different chip or set of chips and other components within network node 1600.11581 The processing circuitry 1602 may comprise a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application-specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, software and / or encoded logic operable to provide, either alone or in conjunction with other network node 1600 components, such as the memory 1604, network node 1600 functionality. For example, the processing circuitry 1602 may be configured to cause the network node to perform the methods as described with reference to any one or more of Figures 7, 9 or 10.11591 In some embodiments, the processing circuitry 1602 includes a system on a chip (SOC). In some embodiments, the processing circuitry 1602 includes one or more of radio frequency (RF) transceiver circuitry 1612 and baseband processing circuitry 1614. In some embodiments, the radio frequency (RF) transceiver circuitry 1612 and the baseband processing circuitry 1614 may be on separate chips (or sets of chips), boards, or units, such as radio units and digital units. In alternative embodiments, part or all of RF transceiver circuitry 1612 and baseband processing circuitry 1614 may be on the same chip or set of chips, boards, or units.11601 The memory 1604 may comprise any form of volatile or non-volatile computer-readable memory including, without limitation, persistent storage, solid-state memory, remotely mounted memory, magnetic media, optical media, random access memory (RAM), readonly memory (ROM), mass storage media (for example, a hard disk), removable storage media (for example, a flash drive, a Compact Disk (CD) or a Digital Video Disk (DVD)), and / or any other volatile or non-volatile, non-transitory device-readable and / or computerexecutable memory devices that store information, data, and / or instructions that may be used by the processing circuitry 1602. The memory 1604 may store any suitable instructions, data, or information, including a computer program, software, an application including one or more of logic, rules, code, tables, and / or other instructions capable of being executed by the processing circuitry 1602 and utilized by the network node 1600. The memory 1604 may be used to store any calculations made by the processing circuitry 1602 and / or any data received via the communication interface 1606. In some embodiments, the processing circuitry 1602 and memory 1604 is integrated.11611 The communication interface 1606 is used in wired or wireless communication of signaling and / or data between a network node, access network, and / or UE. As illustrated, the communication interface 1606 comprises port(s) / terminal(s) 1616 to send and receivedata, for example to and from a network over a wired connection. The communication interface 1606 also includes radio front-end circuitry 1618 that may be coupled to, or in certain embodiments a part of, the antenna 1610. Radio front-end circuitry 1618 comprises filters 1620 and amplifiers 1622. The radio front-end circuitry 1618 may be connected to an antenna 1610 and processing circuitry 1602. The radio front-end circuitry may be configured to condition signals communicated between antenna 1610 and processing circuitry 1602. The radio front-end circuitry 1618 may receive digital data that is to be sent out to other network nodes or UEs via a wireless connection. The radio front-end circuitry 1618 may convert the digital data into a radio signal having the appropriate channel and bandwidth parameters using a combination of filters 1620 and / or amplifiers 1622. The radio signal may then be transmitted via the antenna 1610. Similarly, when receiving data, the antenna 1610 may collect radio signals which are then converted into digital data by the radio front-end circuitry 1618. The digital data may be passed to the processing circuitry 1602. In other embodiments, the communication interface may comprise different components and / or different combinations of components.11621 In certain alternative embodiments, the network node 1600 does not include separate radio front-end circuitry 1618, instead, the processing circuitry 1602 includes radio frontend circuitry and is connected to the antenna 1610. Similarly, in some embodiments, all or some of the RF transceiver circuitry 1612 is part of the communication interface 1606. In still other embodiments, the communication interface 1606 includes one or more ports or terminals 1616, the radio front-end circuitry 1618, and the RF transceiver circuitry 1612, as part of a radio unit (not shown), and the communication interface 1606 communicates with the baseband processing circuitry 1614, which is part of a digital unit (not shown).1163} The antenna 1610 may include one or more antennas, or antenna arrays, configured to send and / or receive wireless signals. The antenna 1610 may be coupled to the radio frontend circuitry 1618 and may be any type of antenna capable of transmitting and receiving data and / or signals wirelessly. In certain embodiments, the antenna 1610 is separate from the network node 1600 and connectable to the network node 1600 through an interface or port.11641 The antenna 1610, communication interface 1606, and / or the processing circuitry 1602 may be configured to perform any receiving operations and / or certain obtaining operations described herein as being performed by the network node. Any information, data and / or signals may be received from a UE, another network node and / or any other networkequipment. Similarly, the antenna 1610, the communication interface 1606, and / or the processing circuitry 1602 may be configured to perform any transmitting operations described herein as being performed by the network node. Any information, data and / or signals may be transmitted to a UE, another network node and / or any other network equipment.11651 The power source 1608 provides power to the various components of network node 1600 in a form suitable for the respective components (e.g., at a voltage and current level needed for each respective component). The power source 1608 may further comprise, or be coupled to, power management circuitry to supply the components of the network node 1600 with power for performing the functionality described herein. For example, the network node 1600 may be connectable to an external power source (e.g., the power grid, an electricity outlet) via an input circuitry or interface such as an electrical cable, whereby the external power source supplies power to power circuitry of the power source 1608. As a further example, the power source 1608 may comprise a source of power in the form of a battery or battery pack which is connected to, or integrated in, power circuitry. The battery may provide backup power should the external power source fail.1166} Embodiments of the network node 1600 may include additional components beyond those shown in Figure 16 for providing certain aspects of the network node’s functionality, including any of the functionality described herein and / or any functionality necessary to support the subject matter described herein. For example, the network node 1600 may include user interface equipment to allow input of information into the network node 1600 and to allow output of information from the network node 1600. This may allow a user to perform diagnostic, maintenance, repair, and other administrative functions for the network node 1600.

[0167] Although the computing devices described herein (e.g., UEs, network nodes, hosts) may include the illustrated combination of hardware components, other embodiments may comprise computing devices with different combinations of components. It is to be understood that these computing devices may comprise any suitable combination of hardware and / or software needed to perform the tasks, features, functions and methods disclosed herein. Determining, calculating, obtaining or similar operations described herein may be performed by processing circuitry, which may process information by, for example, converting the obtained information into other information, comparing the obtained information or converted information to information stored in the network node, and / orperforming one or more operations based on the obtained information or converted information, and as a result of said processing making a determination. Moreover, while components are depicted as single boxes located within a larger box, or nested within multiple boxes, in practice, computing devices may comprise multiple different physical components that make up a single illustrated component, and functionality may be partitioned between separate components. For example, a communication interface may be configured to include any of the components described herein, and / or the functionality of the components may be partitioned between the processing circuitry and the communication interface. In another example, non-computationally intensive functions of any of such components may be implemented in software or firmware and computationally intensive functions may be implemented in hardware.11681 In certain embodiments, some or all of the functionality described herein may be provided by processing circuitry executing instructions stored on in memory, which in certain embodiments may be a computer program product in the form of a non-transitory computer-readable storage medium. In alternative embodiments, some or all of the functionality may be provided by the processing circuitry without executing instructions stored on a separate or discrete device-readable storage medium, such as in a hard-wired manner. In any of those particular embodiments, whether executing instructions stored on a non-transitory computer-readable storage medium or not, the processing circuitry can be configured to perform the described functionality. The benefits provided by such functionality are not limited to the processing circuitry alone or to other components of the computing device, but are enjoyed by the computing device as a whole, and / or by end users and a wireless network generally.

Claims

CLAIMS1. A method performed by a network node in a communications network for configuring a user equipment, UE, with a physical downlink control channel, PDCCH, search space, the method comprising: transmitting a reduced aggregation level, AL, search space configuration to the UE, wherein the reduced AL search space configuration comprises only candidate sets of Control Channel Elements, CCEs, in ALs that are lower than a maximum aggregation level available in a communications network.

2. The method of claim 1, wherein the reduced AL search space configuration comprises only candidate sets of Control Channel Elements that are in AL 1 to AL 4 or AL1 to AL 8.

3. The method of claim 1 or 2, wherein the reduced AL search space configuration is transmitted as part of a Radio Resource Control, RRC, message.

4. The method of any one of claims 1 to 3, further comprising: responsive to determining that a PDCCH transmission to the UE should be made utilizing a first AL with a first transmit power, wherein the first AL is not included in the reduced AL search space configuration, transmitting, with a second transmit power than is higher than the first transmit power, the PDCCH transmission utilizing a second AL that is included in the reduced AL search space configuration.

5. The method of claim 4, further comprising: determining that a PDCCH transmission to the UE should be made utilizing the first AL based on a mapping that maps the first AL to a downlink channel quality associated with the UE.

6. The method of claim 5, further comprising: determining the downlink channel quality from one or more of: channel stateinformation reports from the UE, HARQ feedback from the UE, and uplink reference signals received from the UE.

7. The method of any one of claims 4 to 6, wherein the first AL comprises AL N and the second AL comprises AL N / M, where N is an integer number and M is another integer number, and wherein the first transmit power comprises X W and the second transmit power comprises MX W.

8. The method of any one of claims 1 to 3, further comprising: estimating a downlink SINR, SINR_est, associated with the UE; mapping the SINR est to a first AL, wherein the first AL is included in the reduced AL search space configuration; determining a first transmit power based on a nominal transmit power assumed for SINR est and a minimum downlink SINR, SINR AL s, for which the first AL has minimum threshold probability for successful reception at the UE; and and transmitting a PDCCH transmission utilizing a candidate set of CCEs in the first AL at the first transmit power.

9. The method of claim 8 wherein determining the first transmit power comprises determining the first transmit power as the maximum of 1 or SINR_AL_s / SINR_est times the nominal transmit power.

10. The method of any one of claims 1 to 9, further comprising: performing the step of transmitting the reduced AL search space configuration responsive to determining that a PDCCH blocking level in a cell serving the first UE meets a first threshold condition associated with a first threshold blocking level.

11. The method of claim 10, further comprising: responsive to determining that the PDCCH blocking level in a cell serving the UE does not meet the first threshold condition associated with the first thresholdblocking level, transmitting a normal search space configuration to the UE.

12. The method of claim 10 or 11, wherein: responsive to the PDCCH blocking level meeting the first threshold condition associated with the first threshold blocking level and a meeting a second threshold condition associated with a second threshold blocking level, the reduced AL search space configuration comprises only candidate sets of Control Channel Elements, CCEs, in ALs that are lower than at least a highest Y aggregation levels available in a communications network, where Y is an integer number greater than or equal to 1.

13. The method of claim 12 wherein: responsive to the PDCCH blocking level meeting the first threshold condition associated with the first threshold blocking level and not meeting the second threshold condition associated with a second threshold blocking level, the reduced AL search space configuration comprises only candidate sets of Control Channel Elements, CCEs, in ALs that are lower than at least a highest Z aggregation levels available in a communications network, where Z is an integer number and Z>Y.

14. The method of any one of claims 11 to 13 further comprising: determining the PDCCH blocking level based on one or more of: a fraction of time periods in a plurality of time periods in which PDCCH blocking occurs in the cell; an average amount of unused shared channel PRBs of a type needed by the UE across a plurality of time periods in the cell.

15. A method performed by a user equipment in a communications network for enabling configuration of a Physical Downlink Control Channel, PDCCH search space, the method comprising: receiving, from a network node, a reduced aggregation level, AL, search space configuration, wherein the reduced AL search space configuration comprises only candidate sets of Control Channel Elements, CCEs, in ALs that are lower than amaximum AL available in a communications network.

16. The method of claim 15, wherein the reduced AL search space configuration comprises only candidate sets of Control Channel Elements that are in AL 1 to AL 4.

17. The method of claim 15 or 16, wherein the reduced AL search space configuration is transmitted as part of a Radio Resource Control, RRC, message.

18. A network node in a communications network for configuring a user equipment, UE, with a physical downlink control channel, PDCCH, search space, the network node comprising processing circuitry and memory, the memory containing instructions executable by the processing circuitry whereby the network node is operable to: transmit a reduced aggregation level, AL, search space configuration to the UE, wherein the reduced AL search space configuration comprises only candidate sets of Control Channel Elements, CCEs, in ALs that are lower than a maximum aggregation level available in a communications network.

19. The network node as claimed in claim 18 wherein the memory contains further instructions executable by the processing circuitry whereby the network node is operable to perform the method as claimed in any one of claims 2 to 14.

20. A user equipment in a communications network for enabling configuration of a Physical Downlink Control Channel, PDCCH search space, the user equipment comprising processing circuitry and memory, the memory containing instructions executable by the processing circuitry whereby the user equipment is operable to: receive, from a network node, a reduced aggregation level, AL, search space configuration, wherein the reduced AL search space configuration comprises only candidate sets of Control Channel Elements, CCEs, in ALs that are lower than a maximum AL available in a communications network.

21. The user equipment as claimed in claim 20, wherein the memory contains further instructions executable by the processing circuitry whereby the user equipment isoperable to perform the method as claimed in any one of claims 16 or 17.

22. A computer program, comprising instructions which, when executed on at least one processor, cause the at least one processor to carry out a method according to any of claims 1 to 17.

23. A carrier containing the computer program according to claim 22, wherein the carrier comprises one of an electronic signal, optical signal, radio signal or computer readable storage medium.

24. A computer-readable medium comprising instructions that, when executed on at least one processor, cause the at least one processor to perform the method according to any of claims 1 to 17.

25. A computer program product comprising non transitory computer readable media having stored thereon a computer program according to claim 22.

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