WO2020192923A1

WO2020192923A1 - Guard time adaptation in wireless communication networks

Info

Publication number: WO2020192923A1
Application number: PCT/EP2019/057862
Authority: WO
Inventors: Oana-Elena Barbu; Johannes Harrebek; Benny Vejlgaard; Klaus Ingemann Pedersen; Ping-Heng Kuo
Original assignee: Nokia Technologies Oy
Priority date: 2019-03-28
Filing date: 2019-03-28
Publication date: 2020-10-01

Abstract

According to an example aspect of the present invention, there is provided a method comprising, determining a propagation delay between a first wireless terminal and a second wireless terminal, receiving, from the first wireless terminal, an interference ratio associated with at least one transmission of the second wireless terminal and at least one transmission of a base station, comparing the interference ratio to a threshold and when the interference ratio is below the threshold, setting a guard time based at least partially on the propagation delay between the first wireless terminal and the second wireless terminal.

Description

GUARD TIME ADAPTATION IN WIRELESS COMMUNICATION NETWORKS

FIELD

[0001] Various example embodiments relate in general to wireless communication networks, and guard time adaptation in such networks.

BACKGROUND

[0002] Guard times may be used in wireless communication networks for example to avoid interference between wireless terminals that have been allocated to, or scheduled for, consecutive time resources. Guard times may be exploited in various wireless communication networks, such as, in cellular networks operating according to Long Term Evolution, LTE, and/or 5G radio access technology. 5G radio access technology may also be referred to as New Radio, NR, access technology. Since its inception, LTE has been widely deployed and 3rd Generation Partnership Project, 3GPP, still develops LTE. Similarly, 3GPP also develops standards for 5G/NR. One of the topics in the 3GPP discussions is related to guard time adaptation, and there is a need to provide methods, apparatuses and computer programs for enabling flexible guard time adaptation.

SUMMARY [0003] According to some aspects, there is provided the subject-matter of the independent claims. Some example embodiments are defined in the dependent claims.

[0004] According to a first aspect of the present invention, there is provided a method comprising determining a propagation delay between a first wireless terminal and a second wireless terminal, receiving, from the first wireless terminal, an interference ratio associated with at least one transmission of the second wireless terminal and at least one transmission of a base station, comparing the interference ratio to a threshold and when the interference ratio is below the threshold, setting a guard time based at least partially on the propagation delay between the first wireless terminal and the second wireless terminal. [0005] According to the first aspect of the present invention, the first wireless terminal may be closer to the base station than the second wireless terminal.

[0006] According to the first aspect of the present invention, the first wireless terminal may be scheduled for downlink transmissions and the second wireless terminal may be scheduled for uplink transmissions.

[0007] According to the first aspect of the present invention, the method may further comprise setting the guard time based at least partially on a ramp-off time of the base station when the interference ratio is above the threshold.

[0008] According to the first aspect of the present invention, the method may further comprise determining a propagation delay between the first wireless terminal and the base station and when the interference ratio is below the threshold, setting the guard time based at least partially on the propagation delay between the first wireless terminal and the base station.

[0009] According to the first aspect of the present invention, the method may further comprise determining a propagation delay between the second wireless terminal and the base station and when the interference ratio is below the threshold, setting the guard time based at least partially on the propagation delay between the second wireless terminal and the base station.

[0010] According to the first aspect of the present invention, the method may further comprise setting the guard time at least as large as a sum of the propagation delay between the first wireless terminal and the base station and the propagation delay between the second wireless terminal and the base station, subtracted by the propagation delay between the first wireless terminal and the second wireless terminal.

[0011] According to the first aspect of the present invention, the method may further comprise receiving, from the first wireless terminal, the propagation delay between the first wireless terminal and the second wireless terminal and determining the propagation delay between the first wireless terminal and the second wireless terminal based on the received the propagation delay between the first wireless terminal and the second wireless terminal. [0012] According to the first aspect of the present invention, the method may further comprise transmitting, to the second wireless terminal, a request to start transmitting synchronization signals.

[0013] According to the first aspect of the present invention, the method may further comprise transmitting, to the first user equipment, a request to report the interference ratio.

[0014] According to a second aspect of the present invention, there is provided an apparatus comprising at least one processing core, at least one memory including computer program code, the at least one memory and the computer program code being configured to, with the at least one processing core, cause the apparatus at least to perform a method according to the first aspect of the present invention.

[0015] According to a third aspect of the present invention, there is provided an apparatus comprising means for performing a method according to the first aspect of the present invention.

[0016] According to a fourth aspect of the present invention, there is provided a non- transitory computer readable medium having stored thereon a set of computer readable instructions that, when executed by at least one processor, cause an apparatus to at least perform a method according to the first aspect of the present invention.

[0017] According to a fifth aspect of the present invention, there is provided computer program configured to perform a method according to the first aspect of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIGURE 1 illustrates an exemplary network scenario in accordance with at least some example embodiments; [0019] FIGURE 2 illustrates a first exemplary process in accordance with at least some example embodiments;

[0020] FIGURE 3 illustrates a second exemplary process in accordance with at least some example embodiments; [0021] FIGURE 4 illustrates a scenario concerning multiple sub-bands in accordance with at least some example embodiments;

[0022] FIGURE 5 illustrates an example apparatus capable of supporting at least some example embodiments; [0023] FIGURE 6 illustrates a flow graph of a method in accordance with at least some example embodiments.

EMBODIMENTS

[0024] Guard time adaptation in a wireless communication network may be improved by the procedures described herein. More specifically, flexible and dynamic guard time adaptation may be achieved by determining channel conditions between two User Equipments, UEs, the channel conditions comprising a propagation delay between said two UEs, and adapting the guard time based at least partially on the channel conditions.

[0025] FIGURE 1 illustrates an exemplary network scenario in accordance with at least some example embodiments. According to the example scenario of FIGURE 1, there may be a wireless communication network, which comprises first UE 110, second UE 120, Base Station, BS, 130, and core network element 140. UEs 110 and 120 may be connected to BS 130 via air interface 115. Thus, UEs 110 and 120 may communicate wirelessly with BS 130, or a cell of BS 130, via air interface 115. BS 130 may be considered as a serving BS for UEs 110 and 120. UEs 110 and 120 may be connected to each other via air interface 115 as well. Thus, first UE 110 may encounter interference from second UE 120 over air interface 115, and vice versa.

[0026] UEs 110 and 120 may comprise, for example, a smartphone, a cellular phone, a Machine-to-Machine, M2M, node, Machine-Type Communications, MTC, node, an Internet of Things, IoT, node, a car telemetry unit, a laptop computer, a tablet computer or, indeed, any kind of suitable wireless terminal. That is to say, in some example embodiments a UE may be used as a synonym to a wireless terminal.

[0027] Air interface 115 may be configured in accordance with a Radio Access Technology, RAT, which UEs 110 and 120, along with BS 130 are configured to support. Examples of cellular RATs include Long Term Evolution, LTE, New Radio, NR, which may also be known as fifth generation, 5G, radio access technology and MulteFire. On the other hand, examples of non-cellular RATs include Wireless Local Area Network, WLAN, and Worldwide Interoperability for Microwave Access, WiMAX.

[0028] For instance, in the context of LTE, a BS may be referred to as eNB while in the context of NR, a BS may be referred to as gNB. Also, for example in the context of WLAN, a BS may be referred to as an access point while a UE may be referred to as a mobile station. In general, in some example embodiments a BS may be used as a synonym to a wireless network node. In any case, example embodiments are not restricted to any particular wireless technology. Instead, example embodiments may be exploited in any wireless communication network which exploits guard time adaptation.

[0029] BS 130 may be connected, directly or via at least one intermediate node, with core network element 140 via interface 125. Core network element 140 may be, in turn, coupled via interface 135 with another network (not shown in FIGURE 1), via which connectivity to further networks may be obtained, for example via a worldwide interconnection network. BS 130 may be connected with at least one other BS as well via an inter-base station interface (not shown in FIGURE 1), even though in some example embodiments the inter-base station interface may be absent. BS 130 may be connected, directly or via at least one intermediate node, with core network node 140 or with another core network.

[0030] Concerning duplexing, Frequency Division Duplexing, FDD, and Time Division Duplexing, TDD, modes may be exploited in a wireless communication network. For example, FDD and TDD modes are defined in 3rd Generation Partnership Project, 3GPP, NR Rel-15 specifications. For FDD, non-overlapping carriers may be configured for downlink and uplink transmissions. In case of FDD, the duplexing distance, i.e., frequency separation between uplink and downlink carriers, may be dictated by a spectrum regulator. The duplexing distance may be, e.g., in the range of tens of Megahertz’s. The duplexing distance, along with corresponding UE and BS radio frequency requirements, may be set so that Adjacent Channel Interference, ACI, is tolerable without additional actions.

[0031] Moreover, TDD mode may be defined, e.g., for operation on unpaired frequency bands. In case of TDD, BS 130, or a cell of BS 130, may have exclusive uplink, exclusive downlink, or no transmission at each time instant. So there may be no option for simultaneous uplink and downlink transmission as in case of FDD. In case of TDD a guard time may be inserted between subsequent uplink and downlink transmissions to avoid cross link interference, when switching from downlink transmission to uplink transmission or vice versa.

[0032] For instance, the guard time may be implemented as muting of one or more Orthogonal Frequency Division Multiplexing, OFDM, symbols. A radio frame may be rather flexible, thereby allowing having a series of different slot formats. As an example, the NR specifications may support 56 slot formats, ranging from slots with only downlink transmission to slots with only uplink transmission, and comprising a large number of slot formats in between, i.e., slot formats with a mixture of downlink, uplink and flexible OFDM symbol configurations. A flexible OFDM symbol may be arbitrarily used for downlink, uplink or muted.

[0033] As mentioned above, in case of TDD one challenge is that simultaneous uplink and downlink transmissions may not be supported. This is a challenge for example for Ultra Reliable Low Latency Communications, URLLC, and Time Sensitive Networks, TSNs, wherein multiple simultaneously active UEs would need to be served immediately, and simultaneous uplink and downlink transmissions are therefore often required to accommodate the strict latency/jitter and reliability requirements of UEs.

[0034] Improvements are therefore needed for enhanced flexible duplexing, e.g., for 3GPP NR Rel-17 specifications. For instance, flexible FDD mode may be introduced for unpaired frequency bands, wherein a single unpaired carrier may be utilized more efficiently so that some Physical Resource Blocks, PRBs, may be used for downlink transmission while some other PRBs may be used for uplink transmissions. Such a solution may enable simultaneous downlink and uplink transmissions while still allowing dynamic adjustment of resources for the downlink and uplink transmissions in line with offered traffic.

[0035] However, flexible FDD mode for unpaired frequency bands also comes with a number of implications. For example, flexible FDD mode requires enhanced self- interference mitigation, which may be implemented at BS 130 by using a hybrid of analog filtering and digital Selfinterference Cancellation, SIC, to cope with interference from downlink transmissions that leaks to the resources where BS 130 is at the same time receiving transmissions from several UEs. The enhanced self-interference mitigation increases complexity though, and hence it may be feasible at the BS-side. At the UE-side, the interference between UEs may be handled by proper guard band and guard time adjustments.

[0036] Example embodiments of the present invention may be thus utilized at least for flexible adjustment of the guard time for unpaired frequency bands. For example, example embodiments may be utilized for guard time adaptation between co-scheduled UEs in a setting, wherein flexible FDD is used for unpaired carriers. Example embodiments of the present invention may be exploited, e.g., for 3GPP NR standardization.

[0037] A guard time may be dimensioned, e.g., in NR, to avoid interference between UEs that have been allocated to consecutive time resources. In some cases, the guard time may be fixed at a cell level though, and dimensioned to deal with worst case scenarios. That is to say, the guard time may be set to compensate for high propagation delays due to large cell sizes, to avoid UE interference, and ramp-off times between transmit and receive modes at BS 130, to avoid self- interference. Utilization of a fixed guard time may thus result in inefficient PRB utilization, making low latencies, such 1 ms latency requirement for TSNs, hard to achieve. In addition, overall spectral efficiency may be reduced, which may be an issue for example in case of macro 5G/NR networks (e.g., 3.5 GHz type of deployment).

[0038] Use of a flexible, i.e., adjustable, guard time may enable more efficient spectrum utilization, thereby overcoming the limitations related to the use of fixed guard times. However, one challenge associated with the use of flexible guard times is that a suboptimal guard design may introduce ACI at BS 130 and UEs 110 and 120, because shrinking the guard time between uplink and downlink transmissions causes ACI in time domain.

[0039] With reference to FIGURE 1 again, in some example scenarios BS 130 may operate in an adaptive TDD mode and first UE 110 may be scheduled for a downlink transmission while second UE 120 may be scheduled for an uplink transmission. In some example embodiments, first UE 110 may be in close proximity of BS 130 and second UE 120 may be far away from BS 130. Thus, second UE 120 may need to use high power for uplink transmission and consequently interfere reception of downlink transmission at first UE 110, if the used guard time is too small to compensate for the propagation delay between first UE 110 and second UE 120, thereby leading to ACI at UE 110. [0040] In some example embodiments, the guard time adaptation may be handled by BS 130 to mitigate ACI in time domain, e.g., by taking into account transmit/receive switching capabilities of BS 130 and/or channel conditions (such as propagation delays) between UEs that have been scheduled, or assigned, for consecutive periods for downlink and uplink transmissions.

[0041] Example embodiments enable the dynamic adaptation of a guard time for example on a per UE, per scenario basis. For instance, BS 130 may trigger a process for specific conditions, such as dense network, tight latency requirements, etc. According to some example embodiments, BS 130 may know channel conditions, such as path loss and/or propagation delay, between UEs 110 and 120 that have been allocated, or scheduled, for subsequent uplink and downlink transmissions. Thus, BS 130 may dynamically adjust the guard time based on the channel conditions.

[0042] BS 130 may trigger a message, or a request, from BS 130 to first UE 110 for measuring channel and interference conditions between first UE 110 and second UE 120. In general, first UE 1 10 may be considered as a UE which is closer to BS 130 than second UE 120. Alternatively, or in addition, first UE 110 may be scheduled for downlink transmissions and second UE 120 may be scheduled for uplink transmissions. In some example embodiments, second UE 120 may be considered as a potential aggressor towards first UE 110.

[0043] In some example embodiments, measurements may be performed by first UE 110 in response to the received message, the measurements quantifying an amount of ACI experienced by first UE 110 due to transmission of second UE and a position of first UE 110 relative to second UE 120. The position of first UE 110 relative to second UE 120 may be determined in terms of the propagation delay between first UE 110 and second UE 120. Consequently, first UE 1 10 may report information related to the measurements back to BS 130.

[0044] In some example embodiments, BS 130 may trigger messages from BS 130 to second UE 120 to request information about presence of second UE 120, and possible impact of second UE 120, with respect to first UE 110. Consequently, second UE 120 may report its capabilities in response to the request. For instance, UE sidelink may, or may not, be established depending on capabilities of second UE 120. BS 130 may try to trigger sidelink communication by requesting second UE 120, i.e., an aggressor UE, to transmit synchronization signals to announce its presence. In such a case, if second UE 120 supports sidelink communication, it may report its capability to support sidelink communication to BS 130 in response to the request and also start transmitting synchronization signals for first UE 110. On the other hand, if second UE 120 does not support sidelink communication, it may report, in response to the request, to BS 130 that it does not support sidelink communication. If BS 130 receives information indicating that second UE 120 does not support sidelink communication, it may revert back to using triangulation to determine the propagation delay between first UE 110 and second UE 120.

[0045] Upon receiving the information related to the measurements from first UE 110 and/or capabilities of second UE 120 from second UE 120, BS 130 may process the received information and trigger a process for adaptation of the guard time.

[0046] For instance, in some example embodiments, BS 130 may hence adapt the guard time based at least partially on the propagation delay between first UE 110 and second UE 120, denoted by 5_ab, and a carrier to interference ratio, CIR, observed by UE 110. The carrier to interference ratio, CIR, may be transmitted from first UE 110 to BS 130. Said CIR may be associated with at least one transmission of second UE 120 and at least one transmission of BS 130. For instance, said CIR may be calculated by first UE 110 as follows

CIR RSRP_BS

RSRP_UE 2 (1) wherein RSRP_BS denotes Reference Signal Received Power, RSRP, of a transmission of BS 130, measured by first UE 110. In addition, RSRP_{UE 2} denotes a RSRP of a transmission of second UE 120, measured by first UE 110. In general, the CIR may be referred to as an interference ratio associated with at least one transmission of second terminal 120 and at least one transmission of BS 130, i.e., the CIR is associated with at least one transmission of second terminal 120 and at least one transmission of BS 130 as well. [0047] BS 130 may compute a propagation delay between first UE 110 and BS 130, denoted by d_a, and a propagation delay between second UE 120 and BS 130, denoted by 5_b, and determine that first UE 110 is close to BS 130 whereas second UE 120 is far away from BS 130, e.g., at cell-edge. To avoid ACI at first UE 110, BS 130 may then trigger first UE 110 to perform some measurements. BS 130 may trigger first UE 110 to perform several measurements to be able to detect and avoid ACI at first UE 110, for example using a guard time which is set to minimum for fulfilling a switch-off time of BS 130, i.e., a ramp-off time. That is to say, the ramp-off time may be referred to as the switching-off time in some example embodiments, and the ramp-off time may be defined as the time that it takes for BS 130 to switch from uplink transmission to downlink transmission. In other words, the ramp- off time may refer to a minimum time that is needed for switching from receiving to transmitting, or vice versa.

[0048] FIGURE 2 illustrates a first exemplary process in accordance with at least some example embodiments. On the vertical axes are disposed, from the left to the right, first UE 110, BS 130 and second UE 120 of FIGURE 1. In some example embodiments, first UE 110 may be closer to the base station than second UE 120. Alternatively, or in addition, first UE 110 may be scheduled for downlink transmissions and second UE 120 may be scheduled for uplink transmissions.

[0049] In some example embodiments, BS 130 may have information about exact locations of both, first UE 110 and second UE 120. For instance, the locations may be obtained by triangulation, e.g., by cooperating with two other BSs. Triangulation may be exploited for inferring a propagation delay between first UE 110 and second UE 120, denoted by 5_ab, for example in case of line-of-sight interference path between first UE 1 10 and second UE 120. In such a case, BS 130 may, at step 210, compute propagation delays d_a and 5_b. BS 130 may also determine a relative distance between UEs 110 and 120 and based on the relative distance compute 5_ab, at step 210.

[0050] BS 130 may also request, at step 220, first UE 110 to measure a RSRP of an uplink transmission of UE second 120, RSRP_UE _₂, e.g., uplink Sounding Reference Signal, UL-SRS. Upon receiving the request, first UE 110 may measure, at step 230, the RSRP of an uplink transmission of UE second 120, RSRP_UE _₂. First UE 110 may then also calculate, at step 230, CIR according to Equation (1) and transmit the CIR to BS 130 at step 240. At step 250, BS 130 may trigger the process for adaptation of the guard time.

[0051] FIGURE 3 illustrates a secondary exemplary process in accordance with at least some example embodiments. On the vertical axes are disposed, from the left to the right, first UE 110, BS 130 and second UE 120 of FIGURE 1. In some example embodiments, first UE 110 may be closer to the base station than second UE 120. Alternatively, or in addition, first UE 110 may be scheduled for downlink transmissions and second UE 120 may be scheduled for uplink transmissions. [0052] In some example embodiments, BS 130 may not have information about exact locations of at least one of first UE 1 10 and second UE 120. Thus, BS 130 may not be able to compute 5_ab. However, BS 130 may be able to compute propagation delays d_a and 5_b, and determine 5_ab based on 5_ab received from first UE 110.

[0053] In some example embodiments, the exemplary process of FIGURE 3 may start, at step 310, when BS 130 may transmit at least one reference signal to UEs 110 and 120. At step 320, first UE 110 may determine, or compute, a RSRP of the at least one received reference signal to determine RSRP_bs.

[0054] At step 330, BS 130 may determine a propagation delay between first UE 110 and BS 130, and/or a propagation delay between second UE 120 and BS 130. In some example embodiments, BS 130 may also determine that first UE 110 is far away from BS 130, possibly based on the determined propagation delay between first UE 110 and BS 130. In some example embodiments, BS 130 may also determine that second UE 120 is close to BS 130, possibly based on the determined propagation delay between second UE 120 and BS 130. At step 330, BS 130 may also set a guard time as minimum, i.e., so that the guard time covers a ramp-off time of BS 130.

[0055] At step 340, BS 130 may transmit a request to first UE 110 to start measuring synchronization signals transmitted by second UE 120. The request may be a trigger for performing sidelink measurements, i.e.., measure SS_a. At step 350, BS 130 may transmit a request to second UE 120 to start transmitting synchronization signals for example for first UE 110. The request may be a trigger for generating signals for sidelink measurements, i.e., generate SS_a.

[0056] At step 360, second UE 120 may transmit synchronization signals and consequently first UE 110 may receive said synchronization signals. At step 370, first UE 110 may compute 5_ab and RSRP_UE _₂. Thus, at step 370, first UE 110 may compute CIR according to Equation (1). At step 380, first UE 110 may transmit a report, such as a sidelink state report, comprising 5_ab and CIR. At step 390, BS 130 may trigger the process for adaptation of the guard time.

[0057] So at the end of both, the first and the second exemplary process of FIGURES 2 and 3, respectively, BS 130 may trigger the process for adaptation of the guard time. The process for adaptation of the guard time may comprise determining, by BS 130, whether adjacent leakage is negligible or non-negligible. That is to say, BS 130 may determine whether adjacent leakage, i.e., CIR, is above a threshold or not. The threshold may be predefined. For example, the threshold may depend on traffic type and defined by BS 130. In some example embodiments, BS 130 may allow lower threshold by choosing a more robust modulation and coding scheme.

[0058] If CIR > P, where P is the threshold, then the interference from second UE 120 towards first UE 110 is negligible. Thus, CIR may be above the threshold and BS 130 may set the minimum required guard time to allow for its own ramp-off time, i.e., set the guard time based at least partially on a ramp-off time of BS 130. That is to say, BS 130 may set the guard time as the ramp-off time of BS 130.

[0059] However, if CIR < P, then the interference from second UE 120 towards first UE 110 is not negligible. Thus, CIR may be below the threshold and BS 130 may set guard time based at least partially on the propagation delay between first UE 110 and second UE 120. For instance, BS 130 may dimension the guard time so that it covers 5_ab. In some example embodiments, the guard time may be set based at least partially on d_a and/or S_b. For instance, a condition for the guard time may be the following and the guard time may be set accordingly

GT ³ \d_a + d_ύ— d_aύ \ . (2)

[0060] In some example embodiments, a TDD scenario may be considered, wherein the guard band may be adapted to accommodate consecutive uplink and downlink transmissions for at least two UEs, such as first UE 110 and second UE 120, and in such a case it may be assumed that the at least two UEs use the same frequency resources.

[0061] However, multiple sub-bands may be considered as well if for example first UE 110, needs to be time-scheduled on a set of frequency resources which may be used by multiple other UEs, wherein said multiple other UEs may be multiplexed in frequency, then the process for adaptation of the guard time in accordance with at least some example embodiments may be applied for each sub-band, i.e., certain frequency resource.

[0062] FIGURE 4 illustrates a scenario concerning multiple sub-bands in accordance with at least some example embodiments. In FIGURE 4, an adaptive guard-band method for multiple sub-bands is presented. Time and frequency resources allocated for first UE 110 are denoted by 410, time and frequency resources allocated for second UE 120 are denoted by 420 and time and frequency resources allocated for a third UE are denoted by 430. In such a case, second UE 120 and the third UE may transmit synchronization signals on the allocated frequency resources 420 and 430, respectively, and thus first UE 110 may measure ACI per the allocated frequency resource. For instance, first UE 110 may measure d_c and CIR_x for each sub-band x, wherein d_c and CIR_X are the propagation delay and CIR, respectively, between first UE 110 and a UE scheduled in sub-band x.

[0063] Example embodiments therefore in general provide a way for BS 130 to optimize resource utilization, such as PRB utilization, to cope with network densification and/or stringent latency requirements on a per-UE basis. Also, the process for adaptation of the guard time may be switched on and off according to stringency of a scenario, and BS 130 may fall back to a fixed guard time approach when needed. The process for adaptation of the guard time may be used in combination with the adaptive guard-band method of FIGURE 4 to enable full flexibility of resource allocation.

[0064] FIGURE 5 illustrates an example apparatus capable of supporting at least some example embodiments. Illustrated is device 500, which may comprise, for example, first UE 110, second UE 120, BS 130. Comprised in device 500 is processor 510, which may comprise, for example, a single- or multi-core processor wherein a single-core processor comprises one processing core and a multi-core processor comprises more than one processing core. Processor 510 may comprise, in general, a control device. Processor 510 may comprise more than one processor. Processor 510 may be a control device. A processing core may comprise, for example, a Cortex-A8 processing core manufactured by ARM Holdings or a Steamroller processing core produced by Advanced Micro Devices Corporation. Processor 510 may comprise at least one Qualcomm Snapdragon and/or Intel Atom processor. Processor 510 may comprise at least one application-specific integrated circuit, ASIC. Processor 510 may comprise at least one field-programmable gate array, FPGA. Processor 510 may be means for performing method steps in device 500. Processor 510 may be configured, at least in part by computer instructions, to perform actions.

[0065] A processor may comprise circuitry, or be constituted as circuitry or circuitries, the circuitry or circuitries being configured to perform phases of methods in accordance with example embodiments described herein. As used in this application, the term“circuitry” may refer to one or more or all of the following: (a) hardware-only circuit implementations, such as implementations in only analog and/or digital circuitry, and (b) combinations of hardware circuits and software, such as, as applicable: (i) a combination of analog and/or digital hardware circuit(s) with software/firmware and (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and (c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

[0066] This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[0067] Device 500 may comprise memory 520. Memory 520 may comprise random- access memory and/or permanent memory. Memory 520 may comprise at least one RAM chip. Memory 520 may comprise solid-state, magnetic, optical and/or holographic memory, for example. Memory 520 may be at least in part accessible to processor 510. Memory 520 may be at least in part comprised in processor 510. Memory 520 may be means for storing information. Memory 520 may comprise computer instructions that processor 510 is configured to execute. When computer instructions configured to cause processor 510 to perform certain actions are stored in memory 520, and device 500 overall is configured to run under the direction of processor 510 using computer instructions from memory 520, processor 510 and/or its at least one processing core may be considered to be configured to perform said certain actions. Memory 520 may be at least in part comprised in processor 510. Memory 520 may be at least in part external to device 500 but accessible to device 500.

[0068] Device 500 may comprise a transmitter 530. Device 500 may comprise a receiver 540. Transmitter 530 and receiver 540 may be configured to transmit and receive, respectively, information in accordance with at least one cellular or non-cellular standard. Transmitter 530 may comprise more than one transmitter. Receiver 540 may comprise more than one receiver. Transmitter 530 and/or receiver 540 may be configured to operate in accordance with Global System for Mobile communication, GSM, Wideband Code Division Multiple Access, WCDMA, 5G/NR, Long Term Evolution, LTE, IS-95, Wireless Local Area Network, WLAN, Ethernet and/or Worldwide Interoperability for Microwave Access, WiMAX, standards, for example.

[0069] Device 500 may comprise a Near-Field Communication, NFC, transceiver 550. NFC transceiver 550 may support at least one NFC technology, such as Bluetooth, or similar technologies.

[0070] Device 500 may comprise User Interface, UI, 560. UI 560 may comprise at least one of a display, a keyboard, a touchscreen, a vibrator arranged to signal to a user by causing device 500 to vibrate, a speaker and a microphone. A user may be able to operate device 500 via UI 560, for example to accept incoming telephone calls, to originate telephone calls or video calls, to browse the Internet, to manage digital files stored in memory 520 or on a cloud accessible via transmitter 530 and receiver 540, or via NFC transceiver 550, and/or to play games.

[0071] Device 500 may comprise or be arranged to accept a user identity module 570. User identity module 570 may comprise, for example, a Subscriber Identity Module, SIM, card installable in device 500. A user identity module 570 may comprise information identifying a subscription of a user of device 500. A user identity module 570 may comprise cryptographic information usable to verify the identity of a user of device 500 and/or to facilitate encryption of communicated information and billing of the user of device 500 for communication effected via device 500.

[0072] Processor 510 may be furnished with a transmitter arranged to output information from processor 510, via electrical leads internal to device 500, to other devices comprised in device 500. Such a transmitter may comprise a serial bus transmitter arranged to, for example, output information via at least one electrical lead to memory 520 for storage therein. Alternatively to a serial bus, the transmiter may comprise a parallel bus transmitter. Likewise processor 510 may comprise a receiver arranged to receive information in processor 510, via electrical leads internal to device 500, from other devices comprised in device 500. Such a receiver may comprise a serial bus receiver arranged to, for example, receive information via at least one electrical lead from receiver 540 for processing in processor 510. Alternatively to a serial bus, the receiver may comprise a parallel bus receiver. [0073] Device 500 may comprise further devices not illustrated in FIGURE 5. For example, where device 500 comprises a smartphone, it may comprise at least one digital camera. Some devices 500 may comprise a back-facing camera and a front-facing camera, wherein the back-facing camera may be intended for digital photography and the front facing camera for video telephony. Device 500 may comprise a fingerprint sensor arranged to authenticate, at least in part, a user of device 500. In some example embodiments, device 500 lacks at least one device described above. For example, some devices 500 may lack a NFC transceiver 550 and/or user identity module 570.

[0074] Processor 510, memory 520, transmitter 530, receiver 540, NFC transceiver 550, UI 560 and/or user identity module 570 may be interconnected by electrical leads internal to device 500 in a multitude of different ways. For example, each of the aforementioned devices may be separately connected to a master bus internal to device 500, to allow for the devices to exchange information. However, as the skilled person will appreciate, this is only one example and depending on the example embodiment various ways of interconnecting at least two of the aforementioned devices may be selected without departing from the scope of the example embodiments.

[0075] FIGURE 6 is a flow graph of a method in accordance with at least some example embodiments. The phases of the illustrated first method may be performed by BS 130 or by a control device configured to control the functioning thereof, possibly when installed therein.

[0076] The method may comprise, at step 610, determining a propagation delay between a first wireless terminal and a second wireless terminal. The method may also comprise, at step 620, receiving, from the first wireless terminal, an interference ratio associated with at least one transmission of the second wireless terminal and at least one transmission of a base station. In addition, the method may comprise, at step 630, comparing the interference ratio to a threshold. Finally, the method may comprise, at step 640, setting a guard time based at least partially on the propagation delay between the first wireless terminal and the second wireless terminal when the interference ratio is below the threshold.

[0077] It is to be understood that the example embodiments disclosed are not limited to the particular structures, process steps, or materials disclosed herein, but are extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular example embodiments only and is not intended to be limiting.

[0078] Reference throughout this specification to one example embodiment or an example embodiment means that a particular feature, structure, or characteristic described in connection with the example embodiment is included in at least one example embodiment. Thus, appearances of the phrases “in one example embodiment” or “in an example embodiment” in various places throughout this specification are not necessarily all referring to the same example embodiment. Where reference is made to a numerical value using a term such as, for example, about or substantially, the exact numerical value is also disclosed.

[0079] As used herein, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, various example embodiments and examples may be referred to herein along with alternatives for the various components thereof. It is understood that such example embodiments, examples, and alternatives are not to be construed as de facto equivalents of one another, but are to be considered as separate and autonomous representations.

[0080] In an exemplary example embodiment, an apparatus, such as, for example first UE 110, second UE 120, BS 130, or a device controlling functioning thereof, may comprise means for carrying out the example embodiments described above and any combination thereof.

[0081] In an exemplary example embodiment, a computer program may be configured to cause a method in accordance with the example embodiments described above and any combination thereof. In an exemplary example embodiment, a computer program product, embodied on a non-transitory computer readable medium, may be configured to control a processor to perform a process comprising the example embodiments described above and any combination thereof.

[0082] In an exemplary example embodiment, an apparatus, such as, for example first UE 110, second UE 120, BS 130, or a device controlling functioning thereof, may comprise at least one processor, and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to perform the example embodiments described above and any combination thereof. [0083] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more example embodiments. In the preceding description, numerous specific details are provided, such as examples of lengths, widths, shapes, etc., to provide a thorough understanding of example embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.

[0084] While the forgoing examples are illustrative of the principles of the example embodiments in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the invention. Accordingly, it is not intended that the invention be limited, except as by the claims set forth below.

[0085] The verbs“to comprise” and“to include” are used in this document as open limitations that neither exclude nor require the existence of also un-recited features. The features recited in depending claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of "a" or "an", that is, a singular form, throughout this document does not exclude a plurality.

INDUSTRIAL APPLICABILITY

[0086] At least some example embodiments find industrial application in wireless communication networks, wherein it is desirable to enable guard time adaptation. For example, some example embodiments find industrial application in cellular communication networks, such as NR and LTE. ACRONYMS LIST

3 GPP 3rd Generation Partnership Project

ACI Adjacent Channel Interference

BS Base Station

FDD Frequency Division Duplexing

GSM Global System for Mobile communication IEEE Institute of Electrical and Electronics Engineers IoT Internet of Things

LTE Long-Term Evolution

M2M Machine-to -Machine

MAC Media Access Control

NFC Near-Field Communication

NR New Radio

OFDM Orthogonal Frequency Division Multiplexing PRB Physical Resource Block

RAT Radio Access Technology

RSRP Reference Signal Receive Power

SIC Self Interference Cancellation

SIM Subscriber Identity Module

SRS Sounding Reference Signal

TDD Time Division Duplexing

TSN Time Sensitive Networks UE User Equipment

UI User Interface

URLLC Ultra Reliable Low Latency Communications WCDMA Wideband Code Division Multiple Access WiMAX Worldwide Interoperability for Microwave Access

WLAN Wireless Local Area Network

REFERENCE SIGNS LIST

Claims

CLAIMS:

1. A method, comprising:

- determining a propagation delay between a first wireless terminal and a second wireless terminal;

- receiving, from the first wireless terminal, an interference ratio associated with at least one transmission of the second wireless terminal and at least one transmission of a base station;

- comparing the interference ratio to a threshold; and

- when the interference ratio is below the threshold, setting a guard time based at least partially on the propagation delay between the first wireless terminal and the second wireless terminal.

2. A method according to claim 1, wherein the first wireless terminal is closer to the base station than the second wireless terminal.

3. A method according to claim 1 or claim 2, wherein the first wireless terminal is scheduled for downlink transmissions and the second wireless terminal is scheduled for uplink transmissions.

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

- when the interference ratio is above the threshold, setting the guard time based at least partially on a ramp-off time of the base station.

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

- determining a propagation delay between the first wireless terminal and the base station; and

- when the interference ratio is below the threshold, setting the guard time based at least partially on the propagation delay between the first wireless terminal and the base station.

6. A method according to claim 5, further comprising: - determining a propagation delay between the second wireless terminal and the base station; and

- when the interference ratio is below the threshold, setting the guard time based at least partially on the propagation delay between the second wireless terminal and the base station.

7. A method according to claim 6, further comprising:

- setting the guard time at least as large as a sum of the propagation delay between the first wireless terminal and the base station and the propagation delay between the second wireless terminal and the base station, subtracted by the propagation delay between the first wireless terminal and the second wireless terminal.

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

- receiving, from the first wireless terminal, the propagation delay between the first wireless terminal and the second wireless terminal; and

- determining the propagation delay between the first wireless terminal and the second wireless terminal based on the received the propagation delay between the first wireless terminal and the second wireless terminal.

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

- transmitting, to the second wireless terminal, a request to start transmitting synchronization signals.

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

- transmitting, to the first user equipment, a request to report the interference ratio.

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

- determine a propagation delay between a first wireless terminal and a second wireless terminal; - receive, from the first wireless terminal, an interference ratio associated with at least one transmission of the second wireless terminal and at least one transmission of a base station;

- compare the interference ratio to a threshold; and

- set a guard time based at least partially on the propagation delay between the first wireless terminal and the second wireless terminal when the interference ratio is below the threshold.

12. An apparatus according to claim 11, wherein the at least one memory and the computer program code are further configured to, with the at least one processing core, cause the apparatus at least to perform a method according to any of claims 2 - 10.

13. An apparatus comprising:

- means for determining a propagation delay between a first wireless terminal and a second wireless terminal;

- means for receiving, from the first wireless terminal, an interference ratio associated with at least one transmission of the second wireless terminal and at least one transmission of a base station;

- means for comparing the interference ratio to a threshold; and

- means for setting a guard time based at least partially on the propagation delay between the first wireless terminal and the second wireless terminal when the interference ratio is below the threshold.

14. An apparatus according to claim 13, further comprising means for performing a method according to any of claims 2 - 10.

15. A non-transitory computer readable medium having stored thereon a set of computer readable instructions that, when executed by at least one processor, cause an apparatus to at least perform a method according to any of claims 1 - 10.

16. A computer program configured to perform a method according to any of claims 1 - 10.