Time window selection for full-duplex transmission

Abstract

A communication device (10; 20) sends a first wireless signal. The communication device (10; 20) determines a time window for receiving a second wireless signal concurrently with sending the first wireless signal. The time window is determined to occur when the first wireless signal comprises a repetition pattern of modulation symbols.

Description

[0001] Time Window selection for Full-Duplex Transmission

[0002] Technical Field

[0003] The present invention relates to methods for controlling wireless transmissions and to corresponding devices, systems, and computer programs.

[0004] Background

[0005] Wireless communication technologies may use licensed frequency bands and / or licenseexempt frequency bands. A typical example of a wireless communication technology operating in license-exempt frequency bands is the WLAN (Wireless Local Area Network) technology, according to "IEEE Standard for Information Technology-Telecommunications and Information Exchange between Systems - Local and Metropolitan Area Networks-Specific Requirements - Part 11 : Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications," in IEEE Std 802.11-2020 (Revision of IEEE Std 802.11-2016), pp.1- 4379, 26 Feb. 2021 , in the following denoted as “IEEE 802.11 standard”. The WLAN technology based on the IEEE 802.11 Standard is also referred to as “Wi-Fi”.

[0006] Among the goals of next generation Wi-Fi standards is to improve the performance for low latency services such as automation, cloud gaming and XR (“extended reality”). For example, IEEE project authorization request document P802.11bn, relating to study of UHR (Ultra High Reliability) enhancements of the IEEE 802.11 standard (available online under ’’https: / / mentor.ieee.Org / 802.11 / dcn / 23 / 11-23-0480”), refers to “at least one mode of operation capable of reducing latency by 25% for the 95th percentile of the latency distribution compared to the Extremely High Throughput MAC / PHY operation”.

[0007] For handling event-based traffic, utilization of preemption was suggested. By using preemption, one may interrupt an ongoing transmission in order to prioritize another typically more critical transmission. For example, a longer physical layer protocol data unit (PPDU) can be divided into several small PPDUs in order to leave short time gaps that may be used to interrupt (i.e., preempt) the ongoing PPDU transmission to allow transmissions carrying low latency data to get access to the wireless channel, as for example described in ’’Preemption for Low Latency Application (follow up)” by J. Fang et al., IEEE document 802.11-23 / 1229r1 , August 2023 (available online under “https: / / mentor.ieee.org / 802.11 / dcn / 23 / 11-23-1229-01- Ouhr-preemption-for-low-latency-application-follow-up.pptx”) or in US 2023 / 0208774 A1. With preemption, there is no need to wait for the delivery of the entire PPDU before competing for channel access. However, the configuration of gaps to enable preemption may adversely affect efficiency because in practical situations most of the gaps will not be used for preemption. In other words, due to the gaps spectral resources need to be reserved to enable transmission of a preemption signal but remain unused at many potential preemption occasions.

[0008] Accordingly, there is a need for techniques which allow for efficient transmission of a preemption signal or similar types of signals.

[0009] Summary

[0010] According to an embodiment, a method of controlling wireless transmissions in a wireless communication system is provided. According to the method, a communication device sends a first wireless signal. Further, the communication device determines a time window for receiving a second wireless signal concurrently with sending the first wireless signal. The time window is determined to occur when the first wireless signal comprises a repetition pattern of modulation symbols.

[0011] According to a further embodiment, a method of controlling wireless transmissions in a wireless communication system is provided. According to the method, a communication device determines a time window for sending, to a further communication device sending a first wireless signal, a second wireless signal to be received by the further communication device concurrently with sending of the first wireless signal by the further communication device. The time window is determined to occur when the first wireless signal comprises a repetition pattern of modulation symbols.

[0012] According to a further embodiment, a communication device for operation in a wireless communication system is provided. The communication device is configured to send a first wireless signal. Further, the communication device is configured to determine a time window for receiving a second wireless signal concurrently with sending the first wireless signal. The time window is determined to occur when the first wireless signal comprises a repetition pattern of modulation symbols.

[0013] According to a further embodiment, a communication device for operation in a wireless communication system is provided. The communication device comprises at least one processor and a memory. The memory contains instructions executable by said at least one processor, whereby the communication device is operative to send a first wireless signal. Further, the memory contains instructions executable by said at least one processor, whereby the communication device is operative to determine a time window for receiving a second wireless signal concurrently with sending the first wireless signal. The time window is determined to occur when the first wireless signal comprises a repetition pattern of modulation symbols.

[0014] According to a further embodiment, a communication device for operation in a wireless communication system is provided. The communication device is configured to determine a time window for sending, to a further communication device sending a first wireless signal, a second wireless signal to be received by the further communication device concurrently with sending of the first wireless signal by the further communication device. The time window is determined to occur when the first wireless signal comprises a repetition pattern of modulation symbols.

[0015] According to a further embodiment, a communication device for operation in a wireless communication system is provided. The communication device comprises at least one processor and a memory. The memory contains instructions executable by said at least one processor, whereby the communication device is operative to determine a time window for sending, to a further communication device sending a first wireless signal, a second wireless signal to be received by the further communication device concurrently with sending of the first wireless signal by the further communication device. The time window is determined to occur when the first wireless signal comprises a repetition pattern of modulation symbols.

[0016] According to a further embodiment, a computer program or computer program product is provided, e.g., in the form of a non-transitory storage medium, which comprises program code to be executed by at least one processor of a communication device for operation in a wireless communication system. Execution of the program code causes the communication device to send a first wireless signal. Further, the communication device is configured to determine a time window for receiving a second wireless signal concurrently with sending the first wireless signal. The time window is determined to occur when the first wireless signal comprises a repetition pattern of modulation symbols.

[0017] According to a further embodiment, a computer program or computer program product is provided, e.g., in the form of a non-transitory storage medium, which comprises program code to be executed by at least one processor of a communication device for operation in a wireless communication system. Execution of the program code causes the communication device to determine a time window for sending, to a further communication device sending a first wireless signal, a second wireless signal to be received by the further communication device concurrently with sending of the first wireless signal by the further communication device. The time window is determined to occur when the first wireless signal comprises a repetition pattern of modulation symbols.

[0018] Details of such embodiments and further embodiments will be apparent from the following detailed description.

[0019] Brief Description of the Drawings

[0020] Fig. 1 schematically illustrates a wireless communication system according to an embodiment.

[0021] Fig. 2 schematically illustrates an exemplary scenario where preemption may be implemented in accordance with an embodiment of the present disclosure.

[0022] Figs. 3 schematically illustrated a preemption procedure in accordance with an embodiment of the present disclosure.

[0023] Figs. 4A and 4B schematically illustrate wireless signals in accordance with an embodiment of the present disclosure.

[0024] Figs. 5A and 5B schematically illustrate further wireless signals in accordance with an embodiment of the present disclosure.

[0025] Figs. 6A and 6B schematically illustrate further wireless signals in accordance with an embodiment of the present disclosure.

[0026] Figs. 7A and 7B schematically illustrate modulation of a wireless signal as used in an embodiment of the present disclosure

[0027] Fig. 8 shows a flowchart for schematically illustrating a method according to an embodiment of the present disclosure.

[0028] Fig. 9 shows a flowchart for schematically illustrating a further method according to an embodiment of the present disclosure.

[0029] Fig. 10 schematically illustrates structures of an AP according to an embodiment of the present disclosure. Fig. 11 schematically illustrates structures of a wireless device according to an embodiment of the present disclosure.

[0030] Detailed Description

[0031] In the following, concepts in accordance with exemplary embodiments of the invention will be explained in more detail and with reference to the accompanying drawings. The illustrated embodiments relate to control of wireless communication in a wireless communication system. The wireless communication system may be a WLAN system based on IEEE 802.11 technology. However, it is noted that the illustrated concepts could also be applied to other wireless communication technologies. For example, the wireless communication system could be based on the LTE (Long Term Evolution), NR (New Radio) technology specified by 3GPP (3rd Generation Partnership Project), or the Bluetooth technology.

[0032] In the illustrated concepts, simultaneous transmission and reception of wireless signals by a communication device, in particular full duplex (FD) operation of the communication device may be enabled by selection of a time window in which the communication device sends a first wireless signal and, simultaneously with sending the first wireless signal, receives a second wireless signal. The time window is selected in such a way that, during the time window, the first wireless signal comprises a repetition pattern of modulation symbols. For example, during at least a part of the time window, the first wireless signal may consist of identical copies of a modulation symbol sequence. The identical copies may, e.g., be obtained by repeating each modulation symbol multiple times, e.g., twice. Due to the first wireless signal including the repetition pattern, self-interference (SI) cancellation at the communication device may be facilitated significantly. Accordingly, FD operation of the communication device may be implemented in an efficient manner and without adding excessive complexity. The second wireless signal may in particular include a preemption signal which instructs the communication device to stop sending the first wireless signal, but could additionally or alternatively also carry other data, such as low-data rate information from an Internet-of-Things (loT) device, e.g., a sensor. Accordingly, the FD operation of the communication device may be used to enable transmission of preemption signals or other signals in an efficient manner, without requiring insertion of gaps into wireless signals.

[0033] In some scenarios, the modulation symbols of the repetition pattern may carry data transmitted by the communication device. In other cases, the modulation symbols of the repetition pattern could also correspond to parts of the first wireless signal which are known to include repetitions of modulation symbols, such as midamble parts.

[0034] The determination of the time window may be performed by the communication device, which may thus selectively activate its FD capability during the determined time window(s). Further, the determination of the time window may be performed by another communication device which intends to transmit to the communication device. Such other communication device may then for example transmit a preemption signal to the communication device during the determined time window, so that the communication device may then utilize its FD capability to receive the preemption signal while sending the first wireless signal. In response to receiving the preemption signal, the communication device may stop sending the first wireless signal, so that for example a third wireless signal can be sent to the communication device. The illustrated concepts may thus be utilized to enable preemption in an efficient manner, thereby for example facilitating implementation of low-latency (LL) communication.

[0035] Fig. 1 illustrates an exemplary wireless communication system according to an embodiment. In the illustrated example, the wireless communication system includes multiple APs 10, in the illustrated example referred to as AP1 , AP2, AP3, AP4, and multiple stations 20, in the illustrated example referred to as STA11 , STA21 , STA22, STA31 , and STA41. STA11 is served by AP1 , in a first BSS denoted as BSS1. STA21 and STA22 are served by AP2, in a second BSS denoted as BSS2. STA31 is served by AP3, in a third BSS denoted as BSS3. STA41 is served by AP4, in a fourth BSS denoted as BSS4. The stations 20 may be non-AP STAs and correspond to various kinds of wireless communication devices, for example user terminals, such as mobile or stationary computing devices like smartphones, laptop computers, desktop computers, tablet computers, gaming devices, or the like. Further, the stations 20 could for example correspond to other kinds of equipment like smart home devices, printers, multimedia devices, data storage devices, or the like.

[0036] In the example of Fig. 1 , each of the stations 20 may connect through a radio link to one of the APs 10. For example, depending on location or channel conditions experienced by a given station 20, the station 20 may select an appropriate AP 10 and BSS for establishing the radio link. The radio link may be based on OFDM (Orthogonal Frequency Division Multiplexing) using one or more channels from a frequency spectrum which is shared on the basis of a contentionbased mechanism, e.g., an unlicensed or license-exempt band like the 2.4 GHz ISM (Industrial, Scientific and Medical) band, the 5 GHz band, the 6 GHz band, or the 60 GHz band. Each AP 10 may provide data connectivity of the stations 20 connected or associated to the AP 10. As further illustrated, the APs 10 may be connected to a data network (DN) 110. In this way, the APs 10 may also provide data connectivity between stations 20 connected to different APs 10. Further, the APs 10 may also provide data connectivity of the stations 20 to other entities, e.g., to one or more servers, service providers, data sources, data sinks, user terminals, or the like. Accordingly, the radio link established between a given station 20 and its serving AP 10 may be used for providing various kinds of services to the station 20, e.g., a voice service, a multimedia service, or other data service. Such services may be based on applications which are executed on the station 20 and / or on a device linked to the station 20. By way of example, Fig. 1 illustrates an application service platform 150 provided in the DN 110. The application(s) executed on the station 20 and / or on one or more other devices linked to the station 20 may use the radio link for data communication with one or more other stations 20 and / or the application service platform 150, thereby enabling utilization of the corresponding service(s) at the station 20.

[0037] In the illustrated concepts, FD operation may be utilized by at least some of the APs 10 or stations 20. Specifically, the FD operation may be selectively enabled during time windows where the wireless signal currently being sent by the AP 10 or station 20 includes a repetition pattern of modulation symbols. In this way, SI cancellation at the AP 20 or station 20 can be implemented in an efficient manner, requiring less sophisticated hardware. The selective FD operation in the time window(s) may in particular be utilized to enable sending of a preemption signal. It is however noted that the time windows could also be used for transmission of other kinds of signal to be received based on the FD operation.

[0038] Fig. 2 illustrates an exemplary scenario in which FD capability may be selectively enabled in accordance with the illustrated concepts. The scenario of Fig. 2 involves an AP 10 (denoted as AP1) and a number of stations 20 (denoted as STA1 , STA2, STA3) within coverage of the AP 10. The stations 20 may be connected or associated to the AP 10. In the scenario of Fig. 2, it is assumed that AP1 sends a downlink (DL) wireless transmission to STA1. During some time windows AP1 halves its data-rate by repeating each OFDM symbol twice. During these time windows, AP1 activates a temporary FD capability that allows other devices, such as STA1 , STA2, or STA3, to send an overlaid uplink (UL) wireless transmission to AP1. When AP1 has activated its FD capabilities, it may receive an overlaid UL wireless transmission which may come either from the intended receiver of the transmission by AP1 , in the illustrated example STA1 , or from any other device, e.g., STA2 or STA3. The device sending the overlaid UL wireless transmission may determine or otherwise know the time windows when AP1 has activated its FD capability and may therefore only transmit to AP1 during these time windows. In the following explanations, a device which temporarily activates FD operation in selected time windows, like AP1 in the example of Fig. 2, it also denoted as “first device”. A device which uses the time windows to send a wireless signal to the first device is also denoted as “second device”. In the example of Fig 2, the first device is an AP and the second device may be a STA associated to the AP. But other scenarios are possible as well, e.g., scenarios where the first device is a STA and the second device is the AP to which the STA is associated, or scenarios where the first device is an AP and the second device is another AP, or scenarios where the first device is a STA and the second device is another STA.

[0039] Fig. 3 shows an example of a preemption process which is based on the illustrated concepts. Similar as the scenario of Fig. 2, the example of Fig. 3 involves an AP (denoted as AP1) and stations associated to the AP, denoted as STA1 and STA2. In the example of Fig. 3, it is assumed that AP1 sends a DL PPDll to STAI . During transmission of the DL PPDll, LL data for transmission to AP1 arrives at STA2. STA2 then determines a time window where the DL PPDll being transmitted by AP1 includes a repetition pattern of OFDM symbols and, during such a time window, sends a preemption signal (PS) to AP1. By using FD operation during the time window, AP1 can receive the preemption signal simultaneously with the ongoing transmission of the DL PPDU to STA1. However, in response to receiving the preemption signal, AP1 stops the ongoing transmission of the DL PDDU so that STA2 can use the wireless medium to send a UL PPDU carrying the LL data to AP1.

[0040] The devices involved in the preemption process may exchange or share information regarding, e.g., the activation of the FD operation, location of time windows wherein the FD mode is activated, or the like. Such sharing or exchange of information may differ depending on the type of device. As an example, if the FD capable device is an AP, it may share the information by broadcasting it in a beacon frame. As another example, if the FD capable device is a non- AP STA, it may share the information in a dedicated frame, e.g., in a control frame.

[0041] In some scenarios, a longer time window for sending the preemption signal, in particular a time window which is longer than the duration of the preemption signal, may be used to enable prioritization among different devices attempting to preempt the ongoing transmission. For example, a device with highest priority may transmit the preemption signal within a first part of the time window, while other devices with lower priority may be allowed to only transmit their preemption only in a later part of the time window. In some scenarios, usage of the time window by multiple devices may also be based on a random-access mechanism, for example using a counter at each device. Figs. 4A and 4B illustrate an example of how the repetition pattern can facilitate SI cancellation at the first device, e.g., at AP1 in the examples of Figs. 2 and 3. Fig. 4A and 4B schematically illustrate representation of a logical “0” and a logical “1” in the overlaid signal transmitted by the second device. In the illustrated example, the logical “0” and logical “1” are represented using on-off keying (OOK) on a sequence of four OFDM symbols. For representing the logical “0”, the first OFDM symbol and the third OFDM symbol of the sequence are “ON” signals, and the second OFDM symbol and the fourth OFDM symbol are “OFF” signals. For representing the logical “1”, the first OFDM symbol and the second OFDM symbol are “OFF” signals, and the third OFDM symbol and the fourth OFDM symbol are “ON” signals. It is noted that these representations constitute an example and that similar alternative representations could be used as well.

[0042] Fig. 4B schematically illustrates the received signal at the first device, where the signals representing the logical “0” and the logical “1” are overlaid to the SI of the first device (denoted by “I”). As illustrated, due to the repetition pattern on the first wireless signal, the SI consists of identical copies, each copy having the same duration as OFDM symbol duration of the overlaid second wireless signal.

[0043] The cancellation of the SI at the first device may be implemented as follows: The signals of the first OFDM symbol and of the third OFDM symbol are added, while the signals of the second OFDM symbol and of the fourth OFDM symbol are subtracted. The resulting combined signal is used as input to decode the received wireless signal. As can be seen, when a logical “0” is received, such combination of signals results in twice the transmitted power per OFDM symbol, while when a logical “1” is received, the result is a zero-power signal. Accordingly, the SI part of the received signal may be suppressed, and the power of the useful part corresponding to the overlaid second wireless signal may be enhanced.

[0044] As for example described in ’’Preemption for Low Latency Application (follow up)” by J. Fang et al., IEEE document 802.11 -23 / 1229r1 , August 2023 (available online under “https: / / mentor.ieee.Org / 802.11 / dcn / 23 / 11 -23-1229-01 -Ouhr-preemption-for-low-latency- application-follow-up.pptx”), in some existing solution preemption of an ongoing transmission may be enabled by insertion of time gaps. The time gaps may be inserted by segmenting a PPDU into smaller PPDUs and separating the smaller PPDUs by the time gaps. In the illustrated concepts, such time gaps may be filled with repeated OFDM symbols that carry additional information. Such information may be conveyed with lower data rate than data conveyed by the PPDU segments. Figs. 5A and 5B illustrate examples of corresponding wireless signals. In the example of Fig. 5A, a PPDU to be transmitted by the first device is segmented into smaller PPDlls, denoted as PPDLI1 , PPDLI2, PPDLI3, PPDLI4. In the first wireless signal which is sent by the first device, these PPDll segments are separated by time windows corresponding to a set of repeated OFDM symbols. In the example of Fig. 5A, PPDLI1 and PPDLI2 are separated by two repetitions of an OFDM symbol denoted as “S1”, PPDLI2 and PPDLI3 are separated by two repetitions of an OFDM symbol denoted as “S2”, and PPDLI3 and PPDLI4 are separated by two repetitions of an OFDM symbol denoted as “S3”. In the example of Fig. 5B, PPDLI1 and PPDLI2 are separated by two repetitions of an OFDM symbol denoted as “S1” and two repetitions of an OFDM symbol denoted as “S2”, PPDLI2 and PPDLI3 are separated by two repetitions of an OFDM symbol denoted as “S3” and two repetitions of an OFDM symbol denoted as “S4”, and PPDLI3 and PPDLI4 are separated by two repetitions of an OFDM symbol denoted as “S5” and two repetitions of an OFDM symbol denoted as “S6”. In each case, the repeated OFDM symbols inserted into the time gaps may carry information in addition to the information carried by the PPDll segments. The separation of the PPDll segments may correspond to the duration of the time gaps in the above-mentioned existing solutions, and the time durations of the OFDM symbols inserted into the time gaps may be set accordingly, e.g., to half of the duration of the time gap in the example of Fig. 5A or to one fourth of the duration of the time gap in the example of Fig. 5B. In some scenarios, the separation of the PPDll segments may also be larger than the duration of the time gaps in the above-mentioned existing solutions, which may facilitate hardware implementation, e.g., because time synchronization between devices can be relaxed and / or traffic with some jitter may be accommodated. Such larger separations are possible because the wireless channel is not left unused and regulatory limitations concerning maximum idle time of the wireless channel are not relevant.

[0045] In some scenarios, the repetition pattern of modulation symbols in the time window could also be based on a midamble part of the ongoing first wireless transmission. For example, such midamble parts are defined in the from IEEE 802.11ax High Efficiency (HE) amendment to deal with varying channels. These midambles are implemented by periodically inserting an HE long training field (HE-LTF) between OFDM symbols carrying data in an HE PPDU. Section 27.3.12.16 of the IEEE 802.11 standard describes how an HE STA may include midambles in an HE PDDU transmission in fast varying channels, i.e., channels with high Doppler, to facilitate channel estimation update during the PPDU. Such midambles are inserted only if less than four streams are transmitted. The recipient may use the midambles to update the channel estimation if it is varying fast, which typically is the case in channels with high Doppler shift. Midambles may be present in the Data field of the HE PPDU every 10 or 20 OFDM symbols. Each midamble is the same as the HE-LTF field(s) in the preamble of the same PPDU. The midamble may thus contain 1 or 2 or 4 HE-LTF fields, depending on the number of streams. Fig. 6A illustrates an example of an HE PPDll with midamle. As can be seen, the midamble corresponds to a repetition pattern where modulation symbols corresponding to the HE-LTF appear in a repeated manner.

[0046] In some scenarios, the time window for enabling FD operation of the first device may thus correspond to one or more midamble(s) in the first wireless signal. Accordingly, the FD operation may be enabled during the midambles. Fig. 6B illustrates a corresponding example of the first wireless signal, where a PPDll includes midambles denoted as M1 , M2, and M3. As explained in connection with Fig. 6A, such midambles may include repetition patterns of modulation symbols, such as repetitions of the HE-LTF field. FD operation of the first device may be activated during the time windows when the midambles are transmitted. At the same time, the midambles may be utilized for their regular purpose, e.g., channel estimation update during the PPDll. For example, if midambles are sent after every 10 or 20 OFDM symbols, the time windows which allow for transmission of a preemption signal occur every -140 ps or -280 ps, assuming an OFDM symbol duration in the order of 14 ps. Such periodicity of preemption occasions may be well suited to many practical situations and may enable preemption without loss of spectral efficiency.

[0047] As explained in connection with Figs. 4A and 4B, OOK may be used for the overlaid second wireless signal, which may provide sufficient data rate for many scenarios. Still, a higher data rate of the second wireless signal may be beneficial. This may be achieved by applying the OOK independently per subcarrier. The intended UL receiver, i.e., the first device, may then decode the received UL signal as explained in connection with Figs. 4A and 4B, however by individually considering the signal on each subcarrier. The modulation scheme to be applied depends on how complex the receiver in the first device can be made. For example, modulation schemes could be used which do not require that the receiver in the first device acquires an absolute phase reference. Such absolute phase reference typically requires some kind of training signal to be transmitted by the second device, which would add complexity to both the transmitter (the second device) and the receiver (the first device) of the overlaid signal. In the illustrated examples, the modulations merely require that the receiver acquires a relative phase reference, e.g. using a first symbol as a phase reference for a subsequent second symbol.

[0048] It is also possible to apply error correction coding to the second wireless signal, to improve robustness of the data transfer. For instance, if binary modulation is used on the different subcarriers in an OFDM symbol, the information sent on one OFDM symbol may be encoded with a block code such that k information bits are encoded with code of rate r = k / n and then the resulting n coded bits are sent on n subcarriers in one OFDM symbol. The overlaid second wireless transmission may be synchronized at OFDM symbol level with the first wireless transmission. In some scenarios, sending of the second wireless transmission is allowed only after a legacy preamble part of a PPDll conveyed by the first wireless transmission. In this way, it can be taken into account that the legacy preamble fields may use a different numerology than the remaining parts of the PPDll.

[0049] In some scenarios, the first wireless transmission from the first device (e.g., AP1 in the examples of Figs. 2 and 3) could also be affected by interference due to the overlaid second wireless transmission. For example, in the scenario of Fig. 2 such interference could occur at STA1 , which is the intended recipient of the first wireless transmission, when the overlaid second wireless transmission comes from another device, e.g., STA2. In other words, the first wireless transmission from AP1 is intended for STA1 , and the overlaid second wireless transmission, which is intended for AP1 , comes from STA2 and may generate interference at STA1.

[0050] To address such interference issues, the generation of the second wireless signal may consider the repetition pattern in the first wireless signal. For example, since the first wireless signal from the first device includes the repetition pattern, e.g. two identical OFDM symbols, it can be assumed that the intended receiver of the first wireless signal (e.g., STA1 in the example of Fig. 2) will typically add such repeated parts of the signal. For example, if the first wireless signal includes two repetitions of the same OFDM symbol, the intended recipient of the first wireless signal may add the corresponding signals of the two OFDM symbols, thereby enhancing the effective received signal energy. Based on such operation of the intended receiver, the sender of the second wireless signal may generate the second wireless signal in such a way that the summation of the signals for the first wireless signal will result in cancellation of the corresponding signals in the second wireless signal. For this purpose, the modulation symbols of the second wireless signal which correspond to the repeated modulation symbols in the first wireless signal, also correspond to repetitions of the same modulation symbol, however with inverted sign. Figs. 7A and 7B illustrate a corresponding example of a modulation scheme applied to the second wireless signal. Fig. 7A shows representation of a logical “0”, and Fig. 7B shows representation of a logical “1”. As shown, the representations are based on two OFDM symbols, denoted by “S_a” and “S_b”. The logical “0” is represented by sending a non-zero signal during the first half of each one of the two OFDM symbols, and no signal during the second half of each of the two OFDM symbols. The non-zero signals sent during the first halves of the two OFDM symbols are related such that they are identical, except that the sign is inverted. As can be seen, when adding the signals of symbol S_a and symbol S_b, the result is zero. The logical “1” is represented by sending a no signal during the first half of each one of the two OFDM symbols, and a non-zero signal during the second half of each of the two OFDM symbols. The non-zero signals sent during the second halves of the two OFDM symbols are related such that they are identical, except that the sign is inverted. Again, when adding the signals of symbol S_a and symbol S_b, the result is zero.

[0051] When the second wireless signal is based on antipodal modulation as illustrated in Fig. 7A and 7B, the intended recipient of the second wireless signal (e.g., AP1 in the example of Fig. 2) may operate by subtracting the signals of the two OFDM symbols from each other, which means that the resulting useful signal amplitude is doubled. As compared to that, addition of the signals of the two OFDM symbols by the intended recipient of the first wireless signal (e.g., STA1 in the example of Fig. 2), where a contribution corresponding to the second wireless signal may be present as interference in the received signal, results in cancellation of this interference contribution.

[0052] Fig. 8 shows a flowchart for illustrating a method of controlling wireless transmissions in a wireless communication system, which may be utilized for implementing the illustrated concepts. The wireless communication system may be based on a WLAN technology, e.g., according to the IEEE 802.11 standards family. The method of Fig. 8 may be used for implementing the illustrated concepts in a communication device. Such communication device may correspond to an AP, such as any of the above-mentioned APs 10, or to a non-AP STA, such as any of the above-mentioned stations 20.

[0053] If a processor-based implementation of the communication device is used, at least some of the steps of the method of Fig. 8 may be performed and / or controlled by one or more processors of the communication device. Such communication device may also include a memory storing program code for implementing at least some of the below described functionalities or steps of the method of Fig. 8.

[0054] At step 810, the communication device sends a first wireless signal. The first wireless signal may for example convey a PPDll or segments of a PPDll.

[0055] At step 820, the communication device determines a time window for receiving a second wireless signal concurrently with sending the first wireless signal. The time window is determined to occur when the first wireless signal comprises a repetition pattern of modulation symbols. In some scenarios, mitigation of self-interference at the communication device is based on the repetition pattern. In some scenarios, generation of the second wireless signal is based on the repetition pattern.

[0056] In some scenarios, the second wireless signal is based on antipodal modulation, e.g., as explained in connection with Figs. 7A and 7B. With such antipodal modulation, one part of the second wireless signal may correspond to an inversion of another part of the second wireless signa. Such parts may for example correspond to modulation symbols which are repeated in the first wireless signal.

[0057] In some scenarios, the second wireless signal may be based on OOK, e.g., as explained in connection with Figs. 2A, 2B, 7A, and 7B. In some scenarios, wherein the second wireless signal may be based on individual OOK per subcarrier.

[0058] In some scenarios, reception of the first wireless signal by an intended receiver is based on the repetition pattern. For example, the intended receiver could add parts of its received signal which correspond to repeated modulation symbols of the first wireless signal.

[0059] In some scenarios, the repetition pattern may be based on mapping the same data to at least one first data symbol and to one or more repetitions of the first data symbol, e.g., as explained in connection with Figs. 5A and 5B.

[0060] In some scenarios, the repetition pattern corresponds to at least a part of a midamble sequence of a data unit, e.g., PPDll, carried by the first wireless signal, e.g., as explained in connection with Figs. 6A and 6B.

[0061] In some scenarios, the time window is after a preamble sequence of a data unit, e.g., PPDll, carried by the first wireless signal.

[0062] In some scenarios, modulation symbols of the first wireless signal and modulation symbols of the second wireless signal are time-aligned.

[0063] In some scenarios, the second wireless signal carries a command to stop sending the first wireless signal. For example, the second wireless signal may carry a preemption signal, such as the preemption signal in the example of Fig. 3. In some scenarios, a data rate of the second wireless signal is lower than a data rate of the first wireless signal.

[0064] In some scenarios, a sender of the second wireless signal is an intended recipient of the first wireless signal. Alternatively, a sender of the second wireless signal could be different from an intended recipient of the first wireless signal.

[0065] If the communication device is an AP of the wireless communication system, the first wireless signal is intended for reception by a non-AP station associated to the AP. The second wireless signal may be transmitted by this associated non-AP station or by another non-AP station.

[0066] At step 840, the communication device may receive the second wireless signal in the determined time interval. At step 850, in response to receiving the first wireless signal, the communication device may stop sending the first wireless signal. Having stopped sending the first wireless signal, the communication device may receive a third wireless signal. The preemption process of Fig. 3 is an example of such procedures corresponding to steps 830, 840 and 850.

[0067] Fig. 9 shows a flowchart for illustrating a method of controlling wireless transmissions in a wireless communication system, which may be utilized for implementing the illustrated concepts. The wireless communication system may be based on a WLAN technology, e.g., according to the IEEE 802.11 standards family. The method of Fig. 9 may be used for implementing the illustrated concepts in a communication device. Such communication device may correspond to an AP, such as any of the above-mentioned APs 10, or to a non-AP STA, such as any of the above-mentioned stations 20.

[0068] If a processor-based implementation of the communication device is used, at least some of the steps of the method of Fig. 9 may be performed and / or controlled by one or more processors of the communication device. Such communication device may also include a memory storing program code for implementing at least some of the below described functionalities or steps of the method of Fig. 9.

[0069] At step 910, the communication device determines a time window for sending, to a further communication device which sends a first wireless signal, a second wireless signal to be received by the further communication device concurrently with sending of the first wireless signal. The time window is determined to occur when the first wireless signal comprises a repetition pattern of modulation symbols. The first wireless signal may for example convey a PPDll or segments of a PPDll.

[0070] At step 920, the communication device sends the second wireless signal in the determined time window.

[0071] In some scenarios, mitigation of self-interference at the further communication device is based on the repetition pattern. In some scenarios, generation of the second wireless signal is based on the repetition pattern.

[0072] In some scenarios, the second wireless signal is based on antipodal modulation, e.g., as explained in connection with Figs. 7A and 7B. With such antipodal modulation, one part of the second wireless signal may correspond to an inversion of another part of the second wireless signa. Such parts may for example correspond to modulation symbols which are repeated in the first wireless signal.

[0073] In some scenarios, the second wireless signal may be based OOK, e.g., as explained in connection with Figs. 2A, 2B, 7A, and 7B. In some scenarios, wherein the second wireless signal may be based on individual OOK per subcarrier.

[0074] In some scenarios, reception of the first wireless signal by an intended receiver is based on the repetition pattern. For example, the intended receiver could add parts of its received signal which correspond to repeated modulation symbols of the first wireless signal.

[0075] In some scenarios, the repetition pattern may be based on mapping the same data to at least one first data symbol and to one or more repetitions of the first data symbol, e.g., as explained in connection with Figs. 5A and 5B.

[0076] In some scenarios, the repetition pattern corresponds to at least a part of a midamble sequence of a data unit, e.g., PPDll, carried by the first wireless signal, e.g., as explained in connection with Figs. 6A and 6B.

[0077] In some scenarios, the time window is after a preamble sequence of a data unit, e.g., PPDU, carried by the first wireless signal.

[0078] In some scenarios, modulation symbols of the first wireless signal and modulation symbols of the second wireless signal are time-aligned. In some scenarios, the second wireless signal carries a command to stop sending the first wireless signal. For example, the second wireless signal may carry a preemption signal, such as the preemption signal in the example of Fig. 3.

[0079] In some scenarios, a data rate of the second wireless signal is lower than a data rate of the first wireless signal.

[0080] In some scenarios, the communication device is an intended recipient of the first wireless signal. Alternatively, the communication device could be different from an intended recipient of the first wireless signal.

[0081] If the further communication device is AP of the wireless communication system, the first wireless signal may be intended for reception by a non-AP station associated to the AP. The communication device may correspond to this associated non-AP station or to another non- AP station.

[0082] At step 930, the communication device may send a third wireless signal. For example, sending the second wireless signal may cause the further communication device to stop sending the first wireless signal, so that the communication device may then send the third wireless signal, using spectral resources which were before used for sending the first wireless signal. The preemption process of Fig. 3 is an example of such procedures corresponding to steps 920 and 930.

[0083] Fig. 10 illustrates a processor-based implementation of an AP 1000. The structures as illustrated in Fig. 10 may be used for implementing the above-described concepts in one of the above-mentioned APs 10.

[0084] As illustrated, the AP 1000 includes a radio interface 1010. The radio interface 1010 may for example be based on a WLAN technology, e.g., according to an IEEE 802.11 family standard. However, other wireless technologies could be supported as well, e.g., the LTE technology or the NR technology. In accordance with the illustrated concepts, the radio interface 1010 may support FD operation in selected time windows. Further, the AP 1000 may be provided with a network interface 1020 for connecting to a data network, e.g., using a wire-based connection.

[0085] Further, the AP 1000 may include one or more processors 1050 coupled to the interfaces 1010, 1020, and a memory 1060 coupled to the processor(s) 1050. By way of example, the interfaces 1010, 1020, the processor(s) 1050, and the memory 1060 could be coupled by one or more internal bus systems of the AP 1000. The memory 1060 may include a Read-Only-Memory (ROM), e.g., a flash ROM, a Random Access Memory (RAM), e.g., a Dynamic RAM (DRAM) or Static RAM (SRAM), a mass storage, e.g., a hard disk or solid-state disk, or the like. As illustrated, the memory 1060 may include software 1070 and / or firmware 1080. The memory 1060 may include suitably configured program code to be executed by the processor(s) 1050 so as to implement the above-described functionalities for controlling wireless transmissions, such as explained in connection with the method of Fig. 8 and / or the method of Fig. 9.

[0086] It is to be understood that the structures as illustrated in Fig. 10 are merely schematic and that the AP 1000 may actually include further components which, for the sake of clarity, have not been illustrated, e.g., further interfaces or further processors. Also, it is to be understood that the memory 1060 may include further program code for implementing known functionalities of an AP in an IEEE 802.11 standard compliant technology. According to some embodiments, also a computer program may be provided for implementing functionalities of the AP 1000, e.g., in the form of a physical medium storing the program code and / or other data to be stored in the memory 1060 or by making the program code available for download or by streaming.

[0087] Fig. 11 illustrates a processor-based implementation of a wireless device 1100. The structures as illustrated in Fig. 11 may be used for implementing the above-described concepts in one of the above-mentioned stations 20.

[0088] As illustrated, the wireless device 1100 includes a radio interface 1110. The radio interface 1110 may for example be based on a WLAN technology, e.g., according to an IEEE 802.11 family standard. However, other wireless technologies could be supported as well, e.g., the LTE technology or the NR technology. In accordance with the illustrated concepts, the radio interface 1110 may support FD operation in selected time windows.

[0089] Further, the wireless device 1100 may include one or more processors 1150 coupled to the interface 1110 and a memory 1160 coupled to the processor(s) 1150. By way of example, the interface 1110, the processor(s) 1150, and the memory 1160 could be coupled by one or more internal bus systems of the wireless device 1100. The memory 1160 may include a ROM, e.g., a flash ROM, a RAM, e.g., a DRAM or SRAM, a mass storage, e.g., a hard disk or solid-state disk, or the like. As illustrated, the memory 1160 may include software 1170 and / or firmware 1180. The memory 1160 may include suitably configured program code to be executed by the processor(s) 1150 so as to implement the above-described functionalities for controlling wireless transmissions, such as explained in connection with the method of Fig. 8 and / or the method of Fig. 9.

[0090] It is to be understood that the structures as illustrated in Fig. 11 are merely schematic and that the wireless device 1100 may actually include further components which, for the sake of clarity, have not been illustrated, e.g., further interfaces or further processors. Also, it is to be understood that the memory 1160 may include further program code for implementing known functionalities of a non-AP STA in an IEEE 802.11 standard compliant technology. According to some embodiments, also a computer program may be provided for implementing functionalities of the wireless device 1100, e.g., in the form of a physical medium storing the program code and / or other data to be stored in the memory 1160 or by making the program code available for download or by streaming.

[0091] As can be seen, the concepts as described above may be used for efficiently enabling FD operation in selected time windows. This temporary FD operation may in turn be used for enabling preemption by overlaying a preemption signal onto the ongoing transmission to be preempted. In this way, preemption is possible without requiring time gaps in wireless transmissions. Spectral efficiency can thereby be improved. Further, preemption occasions can be provided with more flexibility, e.g., with a duration that exceeds regulatory limitations of idle time of the wireless medium. Further, existing midambles of wireless transmissions may be used to provide preemption occasions in an efficient manner.

[0092] It is to be understood that the examples and embodiments as explained above are merely illustrative and susceptible to various modifications. For example, the illustrated concepts may be applied in connection with various kinds of wireless technologies, without limitation to WLAN technologies. Moreover, it is to be understood that the above concepts may be implemented by using correspondingly designed software to be executed by one or more processors of an existing device or apparatus, or by using dedicated device hardware. Further, it should be noted that the illustrated apparatuses or devices may each be implemented as a single device or as a system of multiple interacting devices or modules.

Claims

Claims1. A method of controlling wireless communication in a wireless communication system, the method comprising: a communication device (10; 20; 1000; 1100) sending a first wireless signal; and the communication device (10; 20; 1000; 1100) determining a time window for receiving a second wireless signal concurrently with sending the first wireless signal, wherein the time window is determined to occur when the first wireless signal comprises a repetition pattern of modulation symbols.

2. The method according to claim 1 , comprising: wherein mitigation of self-interference at the communication device (10; 20; 1000; 1100) is based on the repetition pattern.

3. The method according to claim 1 or 2, wherein generation of the second wireless signal is based on the repetition pattern.

4. The method according to any of the preceding claims, wherein the second wireless signal is based on antipodal modulation.

5. The method according to any of the preceding claims, wherein the second wireless signal is based on on-off keying.

6. The method according to claim 5, wherein the second wireless signal is based on individual on-off keying per subcarrier.

7. The method according to any of the preceding claims. wherein reception of the first wireless signal by an intended receiver is based on the repetition pattern.

8. The method according to any of the preceding claims, wherein the repetition pattern is based on mapping the same data to at least one first data symbol and to one or more repetitions of the first data symbol.

9. The method according to any of claims 1 to 7, wherein the repetition pattern corresponds to at least a part of a midamble sequence of a data unit carried by the first wireless signal.

10. The method according to any of the preceding claims, wherein the time window is after a preamble sequence of a data unit carried by the first wireless signal.11 . The method according to any of the preceding claims, wherein modulation symbols of the first wireless signal and modulation symbols of the second wireless signal are time-aligned.

12. The method according to any of the preceding claims. wherein the second wireless signal carries a command to stop sending the first wireless signal.

13. The method according to any of the preceding claims, wherein a data rate of the second wireless signal is lower than a data rate of the first wireless signal.

14. The method according to any of the preceding claims, wherein a sender of the second wireless signal is an intended recipient of the first wireless signal.

15. The method according to any of claims 1 to 13, wherein a sender of the second wireless signal is different from an intended recipient of the first wireless signal.

16. The method according to any one of the preceding claims, wherein the wireless communication system is based on a Wireless Local Area Network technology according to the IEEE 802.11 standards family.

17. The method according to claim 16, wherein the communication device (10; 20; 1000; 1100) is an access point, AP, of the wireless communication system.

18. The method according to claim 17, wherein the first wireless signal is intended for reception by a non-AP station associated to the AP.

19. A method of controlling wireless communication in a wireless communication system, the method comprising: a communication device (10; 20; 1000; 1100) determining a time window for sending, to a further communication device (10; 20; 1000; 1100) sending a first wireless signal, a second wireless signal to be received by the further communication device concurrently with sending of the first wireless signal by the further communication device (10; 20; 1000; 1100), wherein the time window is determined to occur when the first wireless signal comprises a repetition pattern of modulation symbols.

20. The method according to claim 19, comprising: wherein mitigation of self-interference at the further communication device (10; 20; 1000; 1100) is based on the repetition pattern.

21. The method according to claim 19 or 20, wherein generation of the second wireless signal is based on the repetition pattern.

22. The method according to any of claims 19 to 21 , wherein the second wireless signal is based on antipodal modulation.

23. The method according to any of claims 19 to 21 , wherein the second wireless signal is based on on-off keying.

24. The method according to claim 23, wherein the second wireless signal is based on individual on-off keying per subcarrier.

25. The method according to any of claims 19 to 24, comprising: the communication device (10; 20; 1000; 1100) receiving the first wireless signal.

26. The method according to claim 25, wherein reception of the first wireless signal by the communication device is based on the repetition pattern.

27. The method according to any of claims 19 to 26, wherein the repetition pattern is based on mapping the same data to at least one first data symbol and to one or more repetitions of the first data symbol.

28. The method according to any of claims 19 to 27,wherein the repetition pattern corresponds to at least a part of a midamble sequence of a data unit carried by the first wireless signal.

29. The method according to any of claims 19 to 28, wherein the time window is after a preamble sequence of a data unit carried by the first wireless signal.

30. The method according to any of claims 19 to 29, wherein modulation symbols of the first wireless signal and modulation symbols of the second wireless signal are time-aligned.31 . The method according to any of claims 19 to 30. wherein the second wireless signal carries a command to stop sending the first wireless signal.

32. The method according to any of claims 19 to 31 , wherein a data rate of the second wireless signal is lower than a data rate of the first wireless signal.

33. The method according to any of claims 19 to 32, wherein the communication device (10; 20; 1000; 1100) is different from an intended recipient of the first wireless signal.

34. The method according to any of claims 19 to 33, wherein the wireless communication system is based on a Wireless Local Area Network technology according to the IEEE 802.11 standards family.

35. The method according to claim 34, wherein the further communication device (10; 20; 1000; 1100) is an access point, AP, of the wireless communication system.

36. The method according to claim 35, wherein the communication device (10; 20; 1000; 1100) is a non-AP station associated to the AP.

37. A communication device (10; 20; 1000; 1100) for a wireless communication system, the communication device (10; 20; 1000; 1100) being configured to: send a first wireless signal; anddetermine a time window for receiving a second wireless signal concurrently with sending the first wireless signal, wherein the time window is determined to occur when the first wireless signal comprises a repetition pattern of modulation symbols.

38. The communication device (10; 20; 1000; 1100) according to claim 37, wherein the communication device (10; 20; 1000; 1100) is configured to perform a method according to any one of claims 2 to 18.

39. The communication device (10; 20; 1000; 1100) according to claim 37 or 38, comprising: at least one processor (1050; 1150), and a memory (1060; 1160) containing program code executable by the at least one processor (1050; 1150), whereby execution of the program code by the at least one processor (1050; 1150) causes the communication device (10; 20; 1000; 1100) to perform a method according to any one of claims 1 to 18.

40. A communication device (10; 20; 1000; 1100) for a wireless communication system, the communication device (10; 20; 1000; 1100) being configured to: determine a time window for sending, to a further communication device (10; 20; 1000; 1100) sending a first wireless signal, a second wireless signal to be received by the further communication device (10; 20; 1000; 1100) concurrently with sending of the first wireless signal by the further communication device (10; 20; 1000; 1100), wherein the time window is determined to occur when the first wireless signal comprises a repetition pattern of modulation symbols.

41. The communication device (10; 20; 1000; 1100) according to claim 40, wherein the communication device (10; 20; 1000; 1100) is configured to perform a method according to any one of claims 20 to 36.

42. The communication device (10; 20; 1000; 1100) according to claim 40 or 41 , comprising: at least one processor (1050; 1150), and a memory (1060; 1160) containing program code executable by the at least one processor (1050; 1150), whereby execution of the program code by the at least one processor (1050; 1150) causes the communication device (10; 20; 1000; 1100) to perform a method according to any one of claims 19 to 36.

43. A computer program or computer program product comprising program code to be executed by at least one processor (1050; 1150) of a communication device (10; 20; 1000; 1100), whereby execution of the program code causes the communication device (10; 20; 1000; 1100) to perform a method according to any one of claims 1 to 36.

Images