Preemption enabling based on time intervals

Abstract

Wireless communication devices (10; 20; 800; 900) generate a first data transmission and a second data transmission on a wireless channel based on orthogonal frequency division multiplexing (OFDM). The first data transmission and the second data transmission are separated by a time gap corresponding to an integer multiple of the sum of the OFDM symbol duration and the guard interval, and allowing the second data transmission to be preempted by starting other transmissions on the wireless channel during the time gap.

Description

Technical Field

[0001] This invention relates to methods for controlling wireless transmission, as well as corresponding devices, systems, and computer programs. Background Technology

[0002] Wireless communication technologies can use licensed and / or unlicensed frequency bands. A typical example of a wireless communication technology operating in an unlicensed frequency band is WLAN (Wireless Local Area Network) technology, as per IEEE Standard 802.11-2020 (a revision of IEEE Standard 802.11-2016), "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" (February 26, 2021, pp. 1-4379) (hereinafter referred to as the "IEEE 802.11 standard"). WLAN technology based on the IEEE 802.11 standard is also known as "Wi-Fi".

[0003] One of the goals of the next-generation Wi-Fi standard is to improve the performance of low-latency services such as automation, cloud gaming, and XR (“extended reality”). For example, the IEEE project authorization request document P802.11bn (available online at “https: / / mentor.ieee.org / 802.11 / dcn / 23 / 11-23-0480”) related to research on UHR (Ultra-High Reliability) enhancements to the IEEE 802.11 standard mentions “at least one operating mode that can reduce latency by 25% for the 95th percentile of the latency distribution compared to extremely high throughput MAC / PHY operation.”

[0004] A known feature designed to handle low-latency services is called R-TWT (Restricted Target Wake-Up Time), and it allows APs (Access Points) to establish periodic scheduling, where certain low-latency services can be prioritized for better protection by ensuring that nearby APs also adhere to the protocol. However, because R-TWT establishes periodic scheduling for transmission, it is less suitable for more irregular low-latency services, such as event-based services or periodic services with jitter.

[0005] To handle event-based services, preemption is also recommended. By using preemption, an ongoing transmission can be interrupted to prioritize another, often more critical, transmission. For example, a long Physical Layer Protocol Data Unit (PPDU) can be divided into several smaller PPDUs to leave short time gaps that can be occupied by transmissions carrying low-latency data, as described in J. Fang et al., “Preemption for Low Latency Application (Follow-up)” (IEEE document 802.11-23 / 1229r1, August 2023, available online at https: / / mentor.ieee.org / 802.11 / dcn / 23 / 11-23-1229-01-0uhr-preemption-for-low-latency-application-follow-up.pptx) or in US 2023 / 0208774 A1. With preemption, it is not necessary to wait for the entire PPDU to be transmitted before contention for channel access.

[0006] However, when a large PPDU is divided into two or more smaller PPDUs to allow preemption, the receiver of the smaller PPDUs typically needs to be able to smoothly continue receiving the smaller PPDUs when no preemption occurs. Since gaps will exist in the received signal, the receiver must ensure that the correct timing is maintained for processing and that the parameters tracked during PPDU reception, such as frequency and phase, are correctly estimated once the next PPDU begins. Moreover, in many cases, transmissions that may be preempted can occur over a large bandwidth, while low-latency data requires only a much smaller bandwidth, suggesting that supporting preemption may be inefficient and wasteful in terms of bandwidth. Furthermore, it can be expected that long-term support will be required for legacy devices that do not support preemption.

[0007] Therefore, there is a need for technologies that allow for the effective preemption of ongoing data transmissions while maintaining compatibility with legacy devices. Summary of the Invention

[0008] According to an embodiment, a method for controlling wireless transmission in a wireless communication system is provided. According to the method, a wireless communication device generates a first data transmission and a second data transmission on a wireless channel based on OFDM (Orthogonal Frequency Division Multiplexing). The first data transmission and the second data transmission are separated by time slots. The time slots correspond to integer multiples of the sum of the OFDM symbol duration and the guard interval, and allow the second data transmission to be preempted by starting other transmissions on the wireless channel during the time slot.

[0009] According to another embodiment, a method for controlling wireless transmission in a wireless communication system is provided. According to the method, a wireless communication device receives a first data transmission on a wireless channel based on OFDM. The first data transmission and a second data transmission on the wireless channel are separated by a time gap, which corresponds to an integer multiple of the sum of the OFDM symbol duration and the guard interval, and allows preemption of the second data transmission by initiating other transmissions on the wireless channel during the time gap.

[0010] According to another embodiment, a wireless communication device is provided. The wireless communication device is configured to generate a first data transmission and a second data transmission on a wireless channel based on OFDM. The first data transmission and the second data transmission are separated by a time gap. The time gap corresponds to an integer multiple of the sum of the OFDM symbol duration and the guard interval, and allows preemption of the second data transmission by initiating other transmissions on the wireless channel during the time gap.

[0011] According to another embodiment, a wireless communication device is provided. The wireless communication device includes at least one processor and a memory. The memory contains instructions executable by the at least one processor, thereby enabling the wireless communication device to operate to generate a first data transmission and a second data transmission on a wireless channel based on OFDM. The first data transmission and the second data transmission are separated by time gaps. The time gaps correspond to integer multiples of the sum of the OFDM symbol duration and the guard interval, and allow the second data transmission to be preempted by initiating other transmissions on the wireless channel during the time gap.

[0012] According to another embodiment, a wireless communication device is provided. The wireless communication device is configured to receive a first data transmission on a wireless channel based on OFDM. The first data transmission and a second data transmission on the wireless channel are separated by a time gap, which corresponds to an integer multiple of the sum of the OFDM symbol duration and the guard interval, and allows preemption of the second data transmission by initiating other transmissions on the wireless channel during the time gap.

[0013] According to another embodiment, a wireless communication device is provided. The wireless communication device includes at least one processor and a memory. The memory contains instructions executable by the at least one processor, thereby enabling the wireless communication device to operate to receive a first data transmission on a wireless channel based on OFDM. The first data transmission and a second data transmission on the wireless channel are separated by a time gap corresponding to an integer multiple of the sum of the OFDM symbol duration and the guard interval, and allowing preemption of the second data transmission by initiating other transmissions on the wireless channel during the time gap.

[0014] According to another embodiment, a computer program or computer program product is provided, for example, in the form of a non-transitory storage medium, comprising program code to be executed by at least one processor of a wireless communication device. Execution of the program code causes the wireless communication device to generate a first data transmission and a second data transmission on a wireless channel based on OFDM. The first data transmission and the second data transmission are separated by time gaps. The time gaps correspond to integer multiples of the sum of the OFDM symbol duration and the guard interval, and allow the second data transmission to be preempted by initiating other transmissions on the wireless channel during the time gap.

[0015] According to another embodiment, a computer program or computer program product is provided, for example, in the form of a non-transitory storage medium, comprising program code to be executed by at least one processor of a wireless communication device. Execution of the program code causes the wireless communication device to receive a first data transmission on a wireless channel based on OFDM. The first data transmission and a second data transmission on the wireless channel are separated by a time gap corresponding to an integer multiple of the sum of the OFDM symbol duration and the guard interval, and allowing preemption of the second data transmission by initiating other transmissions on the wireless channel during the time gap.

[0016] Details of this embodiment and further embodiments will become apparent from the following detailed description. Attached Figure Description

[0017] Figure 1 A wireless communication system according to an embodiment is illustrated schematically.

[0018] Figure 2A This schematically illustrates an example of downlink data transmission being preempted by another downlink transmission according to the illustrated concept.

[0019] Figure 2B An example illustrating how downlink data transmission is preempted by uplink data transmission according to the illustrated concept is shown.

[0020] Figure 2C This schematically illustrates another example of downlink data transmission being preempted by uplink data transmission according to the illustrated concept.

[0021] Figure 3A An OFDM signal is schematically shown, in which the sequence of OFDM symbols is separated by a guard interval.

[0022] Figure 3B The illustration schematically shows the time gaps being inserted into the sequence of OFDM symbols.

[0023] Figure 3C The dimensions of the time gap according to an embodiment of the present disclosure are schematically shown.

[0024] Figure 4 An example of preemption on a portion of bandwidth is illustrated schematically according to an embodiment of the present disclosure.

[0025] Figure 5 Another example of preemption on a portion of bandwidth is illustrated schematically according to an embodiment of the present disclosure.

[0026] Figure 6 A flowchart illustrating a method according to an embodiment of the present disclosure is shown.

[0027] Figure 7 A flowchart illustrating another method according to an embodiment of the present disclosure is shown.

[0028] Figure 8 The structure of an AP according to an embodiment of the present disclosure is illustrated schematically.

[0029] Figure 9 The structure of a wireless device according to an embodiment of the present disclosure is illustrated schematically. Detailed Implementation

[0030] In the following, the concepts of exemplary embodiments according to this disclosure will be described in more detail with reference to the accompanying drawings. The illustrated embodiments relate to controlling wireless transmissions in a wireless communication system. The wireless communication system may be a WLAN system based on IEEE 802.11 technology. However, it should be noted that the illustrated concepts are also applicable to other wireless communication technologies, such as competition-based models of LTE (Long Term Evolution) or NR (New Radio) technologies as defined by 3GPP (3rd Generation Partnership Project).

[0031] In the illustrated concept, preemption is enabled by inserting time gaps between OFDM-based data transmissions on a wireless channel. Data transmission can be caused by dividing a PPDU into smaller segments. These smaller segments may also be referred to herein as packets or small PPDUs. The time gap can also be considered as a specific type of inter-frame interval (IFS). The duration of the time gap is chosen to be an integer multiple corresponding to the sum of the duration of the OFDM symbol and the guard interval (GI), and sufficient to allow transmission to begin within the time gap to preempt upcoming data transmission. By selecting the duration of the time gap in this way, the receiver transmitting data can maintain OFDM symbol timing without requiring resynchronization between data transmissions. Furthermore, maintaining phase reference and / or fast channel tracking across OFDM subcarriers can be facilitated. In addition, the selection of the time gap duration helps ensure that only a portion of the available bandwidth of the wireless channel needs to be allocated to enable preemption. High efficiency can be achieved in this manner. Furthermore, the adverse effects on legacy devices that do not support preemption can be avoided, making coexistence of legacy devices with preemption-supporting wireless communication devices according to the illustrated concept possible.

[0032] Figure 1 An exemplary wireless communication system according to an embodiment is illustrated. In the illustrated example, the wireless communication system includes a plurality of APs 10, referred to in the illustrated example as AP1, AP2, AP3, and AP4, and a plurality of stations 11, referred to in the illustrated example as STA11, STA12, STA13, STA21, STA22, STA31, and STA41. STA11, STA12, and STA13 are served by AP1 in a first BSS (Basic Service Set) labeled BSS1. STA21 and STA22 are served by AP2 in a second BSS labeled BSS2. STA31 is served by AP3 in a third BSS labeled BSS3. STA41 is served by AP4 in a fourth BSS labeled BSS4. Stations 20 may be non-AP STAs and correspond to various types of wireless devices, such as user terminals, such as mobile or fixed computing devices, such as smartphones, laptops, desktop computers, tablets, gaming devices, etc. Furthermore, station 20 can correspond to other types of devices, such as smart home devices, printers, multimedia devices, data storage devices, etc.

[0033] exist Figure 1In the example, each station 20 can connect to an AP 10 via a radio link. For example, depending on the location of a given station 20 or the channel conditions experienced by a given station 11, station 20 can select an appropriate AP 10 and BSS for establishing a radio link. The radio link can be based on one or more OFDM carriers from spectrum shared according to a contention-based mechanism (e.g., unlicensed or unlicensed bands, such as the 2.4 GHz ISM (Industrial, Scientific, and Medical) band, the 5 GHz band, the 6 GHz band, or the 60 GHz band).

[0034] Each AP 10 can provide data connectivity to stations 20 connected to AP 10. As further shown, AP 10 can be connected to a data network (DN) 110. In this way, AP 10 can also provide data connectivity between stations 20 connected to different AP 10s. Furthermore, AP 10 can also provide data connectivity between stations 20 and other entities (e.g., one or more servers, service providers, data sources, data hubs, user terminals, etc.). Therefore, the radio link established between a given station 20 and its serving AP 10 can be used to provide various types of services to station 20, such as voice services, multimedia services, or other data services. Such services can be based on applications executed on and / or on devices linked to station 20. For example, Figure 1 An application service platform 150 provided in DN 110 is illustrated. Applications(one) running on station 20 and / or on one or more other devices linked to station 20 can use radio links to communicate data with one or more other stations 20 and / or application service platform 150, thereby enabling the utilization of corresponding services(one) at station 20. Furthermore, it should be noted that in some scenarios, direct radio links between stations 20 or radio links between APs 10 can also be utilized. The latter radio links can be used, for example, to forward data from one BSS to another and / or to coordinate the operation of APs 10.

[0035] According to the explained concept, preemption of data transmissions is enabled by providing time slots in the OFDM signals used for data transmission between at least some APs 10 and their associated stations 20. The time slots have a duration sufficient to allow preemption of an upcoming data transmission to begin, thus enabling the initiation of low-latency data transmission. The time slots can divide larger PPDUs into smaller segments, eliminating the need to wait for the PPDU to finish before initiating low-latency data transmission. The duration of the time slots is selected based on the principles mentioned above, i.e., it is chosen to correspond to an integer multiple of the sum of the OFDM symbol duration and the GI.

[0036] In the example described in further detail below, it is assumed that data transmission occurs between AP 10 and one or more stations 20 associated with AP 10. Further, it is assumed that the AP controls the wireless channel after winning a contention for it, and then uses a transmission opportunity (TXOP) to reserve the channel. It is assumed that AP 10 sends downlink (DL) data to one or more associated stations 20 and / or receives uplink (UL) data from one or more associated stations 20. DL data and / or UL data may correspond to low-latency (LL) data or non-LL data.

[0037] Figure 2A , Figure 2B and Figure 2C Examples of preempting DL data transmission by initiating a transmission within a time slot are illustrated. In these examples, it is assumed that the DL data transmission is from the AP to the first station (STA1). The time slot divides the DL transmission into several shorter segments and allows another data transmission to be initiated before the DL data transmission ends. Figure 2A In the example, suppose that at some point, LL data for the second station (STA2) arrives at the AP. In the next time slot (TG), the AP therefore begins sending LL data to STA2. Afterwards, DL data transmission to STA1 can continue. Figure 2B In the example, suppose that at some point, LL data for AP arrives at the second station (STA2). In the next time interval (TG), STA2 therefore begins sending LL data to AP. Afterwards, DL data transmission to STA1 can continue. Figure 2CIn the example, suppose that at some point, LL data for AP arrives at the second station (STA2). In the next time slot (TG), STA2 sends a scheduling request (SR) to AP. In response to the scheduling request, AP sends a trigger frame (TF) to STA2. In response to the TF, STA2 sends LL data to AP. After that, DL data transmission to STA1 can continue. Further details of this preemption process can be found in J. Fang et al., “Preemption for Low-Latency Application (Follow-up)” (IEEE document 802.11-23 / 1229r1, August 2023, available online at https: / / mentor.ieee.org / 802.11 / dcn / 23 / 11-23-1229-01-0uhr-preemption-for-low-latency-application-follow-up.pptx) or in US 2023 / 0208774 A1. These examples illustrate that current DL data transmission may be preempted or continue, depending on whether LL traffic is present or absent, and preemption is possible by initiating transmission within a time slot. It should also be noted that, in most cases, preemption will not occur. This is attributable to the fact that for many (especially event-driven) LL applications, LL data arrives relatively infrequently but in unpredictable ways.

[0038] When preemption is present, the typical duration of LL data transmission will be approximately 100 μs - 1 ms. This means that once DL data transmission is resumed, the wireless channel between the transmitter and receiver may have changed significantly, and time, frequency, and phase synchronization between the transmitter and receiver may also be lost due to relative drift. This implies that the transmission of a portion of the DL data arriving after preemption may require allowing the receiver to resynchronize and perform channel estimation in a manner similar to that at the start of the transmission. Therefore, the next portion of DL data transmission after preemption may contain fields for parameter estimation. A natural choice could be to reuse the same fields used for the first transmission, i.e., the traditional preamble and second preamble as specified in the IEEE 802.11 standard, with their contents depending on Wi-Fi generation. The following description focuses on the case without preemption and is therefore applicable, without considering the details related to resynchronization in the case of preemption.

[0039] When there is no preemption, the portions of DL data transmission are separated only by time slots, which have a much shorter duration than LL data transmission. Regarding the duration of these time slots, the following factors need to be considered:

[0040] Standard 1: The duration of the time gap should be short enough to ensure that it does not cause preemptive devices to discover the channel is busy. When a device operates under the DCF (Distributed Coordination Function) channel access scheme of the IEEE 802.11 standard to transmit data, the shortest time that the device must find the channel to be idle is the DCF inter-frame interval (DIFS), which is equal to 16 + 2 × 9 = 34 μs. Therefore, any choice of time gap less than 34 μs satisfies this requirement.

[0041] Standard 2: The duration of the time slot should be long enough for a device intended to trigger preemption to detect that the channel is idle, switch from receiving to transmitting, and begin transmitting. This time can vary depending on the specific implementation and the capabilities of the device. However, since the time slot duration in Wi-Fi systems is 9 μs, this can be used as a reasonable constraint that can be implemented.

[0042] At first glance, a promising choice for the time slot would seem to be 16 + 9 = 25 μs. However, this choice can actually introduce drawbacks. To address this, we can first consider what an OFDM signal typically looks like: it consists of multiple OFDM symbols. The duration of an OFDM symbol is determined by the sampling rate used to generate the OFDM symbol and the FFT (Fast Fourier Transform) size. Taking IEEE 802.11ax as an example, for a 20 MHz channel bandwidth, the sampling rate is 20 MHz, and the FFT size is 256, resulting in a symbol duration of 256 / 20 MHz = 12.8 μs. Furthermore, a GI is added before each OFDM symbol. The duration of the GI is chosen based on the expected excessive delay of the channel, and for IEEE 802.11ax, the GI can be 0.8 μs, 1.6 μs, or 3.2 μs. For most cases, the shortest GI = 0.8 μs is sufficient, and when using this GI, the duration of the OFDM symbol plus the GI equals 13.6 μs. Figure 3A This characteristic of OFDM signals is illustrated schematically.

[0043] Receiver processing of OFDM symbol sequences typically involves many steps; however, it's worth noting that the FFT is usually operated at a fixed frequency, corresponding to an application of the FFT every 13.6 μs. It should also be noted that the exact position of the FFT window is generally not critical to performance (the GI is typically chosen with some margin, so shifting the FFT window a few samples in either direction usually does not affect performance). However, once the position of the FFT window relative to the OFDM symbol timing has been chosen, that position should not be changed, as this would result in a change in the effective channel, as seen after the FFT, even if the physical channel remains the same. This change would, for example, mean that the phase estimate must be updated even if the channel is static.

[0044] Figure 3B This schematically illustrates how the 25 μs time gap in the OFDM signal affects the OFDM symbol timing following that time gap, i.e., in a way that there is a shift in the OFDM symbol timing. This shift will also require updates to the FFT window timing.

[0045] As discussed above, it is generally desirable to avoid updating the timing of the FFT window relative to the OFDM symbol timing. To achieve this, the concepts described involve a specific choice of the duration of the time gap, i.e., as a suitable multiple of the sum of the OFDM symbol duration and the GI duration. Figure 3C A corresponding example is shown. Figure 3C In the example, the time gap was chosen to be twice the duration of the OFDM symbol plus the GI, i.e., 27.2 μs. Considering the preemption enabling considerations mentioned above, especially Standard 1 and Standard 2 described above, the duration of the time gap corresponding to a single OFDM symbol plus the GI would also be possible, while the time gap corresponding to three times the duration of the OFDM symbol plus i GIs would result in an excessively long time gap (> 34 μs).

[0046] Therefore, as discussed above, aligning the duration of the time gap with the OFDM symbol duration plus the GI alignment constitutes an attractive approach. Additionally or alternatively, (potentially residual) misalignment can also be compensated. This compensation can be based on knowledge of the misalignment. When considering, for example, the above example and assuming the OFDM signal carries data from a single user, if the misalignment is 2.2 μs (e.g., in...),... Figure 3BIn a scenario where the sampling rate is 20 MHz, the receiver can advance the FFT window by simply incrementing the corresponding amount. For example, if the sampling rate is 20 MHz, advancing the FFT window by 2.2 μs would correspond to advancing the FFT window by 20 × 2.2 = 44 samples. In this compensation, the advance of the FFT window is based on knowledge of the characteristics of the transmitted OFDM signal, rather than on an estimate at the receiver. For example, if each portion of the transmission begins with a field for estimating, for example, time, frequency, phase, and / or other channel characteristics, there is a relatively high probability that the estimated sample timing will deviate from the sample timing found for the previous portion of the transmission by one or more samples. In the above discussion, it has been shown that, for example, using a phase estimate from a previous portion of the transmission when receiving the currently received portion is not straightforward. However, based on the alignment and / or compensation of the time gap duration shown, it can be utilized that, due to the short duration of the time gap, it may not be necessary to perform an estimation, and that the previous estimation can be reused even if it is slightly outdated. The generalization of this solution for MU-OFDMA (Multi-User Orthogonal Frequency Division Multiplexing Access) transmission will be discussed further below.

[0047] Various technical aspects related to preemption based on dividing large data transmissions (e.g., PPDUs) into smaller portions separated by time slots have been described. Example scenarios based on the illustrated concepts include:

[0048] Example Scenario 1: Alignment of the duration of the time gap with the duration of the OFDM symbol

[0049] In this example scenario, the duration of the time gap is selected as an integer multiple of the sum of the OFDM symbol duration and the GI. If multiple GI values ​​are supported for the same OFDM symbol duration, one option in this example scenario is that the time gap is selected to be aligned relative to only one supported GI value. Another option would be to vary the time gap depending on which supported GI value is actually used.

[0050] Example Scenario 2: Partial Bandwidth Preemption for Multi-User DL Transmission

[0051] In the example above, preemption was discussed when the preempted transmission was for a single receiver. However, the concepts illustrated also apply to preemption enabling multi-user transmissions. In this example scenario, preemption of multi-user transmissions, for example using OFDMA, is considered as follows: Figure 4 As shown.

[0052] As an example, Figure 4The diagram illustrates the transmission of DL data from the AP to / from four stations (STA1, STA2, STA3, and STA4). This transmission could, for example, correspond to a scenario where the total bandwidth of the wireless channel is 80 MHz and each of the four stations is allocated a 20 MHz sub-channel.

[0053] Since LL data may correspond to only a small amount of data in many cases, the entire 80MHz bandwidth is not required for LL data. Therefore, according to this example scenario, preemption is limited to one user, STA4 in the example shown. As explained above, the time slots used to enable preemption can be aligned with the OFDM symbol duration as described above. This is advantageous because the transmissions to all four stations are generated by a single IFFT. Therefore, the OFDM symbols used for different stations are aligned. Aligning the time slots with the OFDM symbol duration plus the GI allows this alignment to be maintained effectively.

[0054] It should also be noted that the underlying principle of this example scenario also allows for preemption when communicating with legacy devices. Specifically, to introduce preemption, a station that might be preempted may need to know that time gaps will exist in the transmission. However, this knowledge may not be assumed for legacy devices. Figure 4 In the example scenario, however, it can be seen that enabling preemption for STA4 does not affect STA1, STA2, and STA3. In other words, STA1, STA2, and STA3 can be legacy devices.

[0055] Example Scenario 3: Partial bandwidth UL preemption for multi-user DL transmission

[0056] In the previous example scenario, it was assumed that preemption was initiated by the AP. For example, in... Figure 2A As explained in the context, preemption of DL transmission essentially means that the AP will send a request to a station (in...). Figure 2A In the scene, it is STA1, in Figure 4In the scenario where the STA4 transmission is replaced by a transmission to another station, the LL transmission may need to interrupt the ongoing DL transmission if the LL transmission is from the STA to the AP. This may require the AP to be able to transmit and receive simultaneously, albeit not on the same frequency, when the DL transmission is to multiple users and it is expected that time slots will be introduced only for a portion of the DL bandwidth. This capability is often referred to as Subband Full-Duplex (SBFD). While implementing SBFD may be challenging, it is anticipated that aligning the OFDM symbols used for UL transmissions with those used for DL ​​transmissions will facilitate SBFD implementation. Aligning UL transmissions with DL transmissions can be considered the task of the station transmitting the LL transmission. Methods for achieving this alignment are described, for example, in WO 2023 / 046287 A1 and can be reused in the concepts of this disclosure for aligning UL transmissions that cause preemption of DL transmissions. Moreover, in the case of preemption of UL transmissions, the time slot used to enable preemption will be aligned with the OFDM symbol duration plus GI, i.e., aligned with the OFDM signal transmitted in the DL. It should be further noted that the time slot for enabling UL transmission preemption can also enable DL transmission preemption (e.g., as in...). Figure 4 (As in the example). Furthermore, it should be noted that in scenarios where time slots are provided only in a portion of the bandwidth to enable preemption of UL transmissions, the same applies. Figure 4 Similar approaches are provided in the examples to allow coexistence with traditional devices.

[0057] Example Scenario 4: Partial Bandwidth Preemption for Multi-User UL Transmission

[0058] Similar to example scenarios 2 and 3, when the ongoing transmission (which can be preempted) is a multi-user UL transmission, such as one based on UL OFDMA, preemption can also be enabled within a portion of the bandwidth.

[0059] For example, when referring again Figure 4In this scenario, it can be assumed that STA1, STA2, and STA3 transmit UL data to the AP in a continuous and non-preemptive manner using their respective allocated frequency resources, while STA4 transmits data to the AP in a discontinuous and preemptive manner (i.e., segmented by time slots). The time slots between different portions of the UL transmission from STA4 can again correspond to integer multiples of the OFDM symbol duration added to the GI. This ensures that there is no OFDM inter-symbol interference on different bandwidth portions during reception at the AP. In this case, another station (e.g., STA5) can preempt STA4's UL transmission by transmitting during a time slot. In this case, STA5 can use the time required to transmit its LL data to the AP on the corresponding sub-channel. Alternatively, STA5 can simply send a scheduling request to the AP, and upon receiving the scheduling request, the AP can prioritize STA5's scheduling in the next triggered UL transmission opportunity. In the latter variation, STA4 can be able to resume its original transmission to the AP before STA5 begins transmitting LL data.

[0060] It should also be noted that the following may occur in Example Scenario 4:

[0061] • STA5 is within the range of STA4. In this case, STA5 can track STA4's transmission and identify time gaps and preemption opportunities in real time. Furthermore, STA4 can detect STA5's transmission and pause / abort it in a timely manner.

[0062] • STA5 is not within the range of STA4. In this case, STA5 may need to rely on the initial control frame (e.g., a trigger frame sent by the AP) to estimate when to preempt STA4's transmission at the appropriate time, i.e., the appropriate time corresponding to a time slot, which will need to be estimated based on calculation rather than real-time tracking of STA4's transmission. Furthermore, STA4 may not be able to detect STA5's transmission and therefore continue its original transmission. If this occurs, STA5's transmission will need to be received at the AP with a suitable signal-to-interference-plus-noise ratio (SINR) for it to be successfully received.

[0063] In Example Scenario 4, preemption can also be supported without affecting coexistence with traditional devices.

[0064] Example Scenario 5: Partial bandwidth preemption for multi-user UL transmission via DL

[0065] In this example scenario, the AP can preempt an ongoing multi-user UL transmission on a portion of the bandwidth, for example, with the aim of sending urgent DL data to an associated station.

[0066] Refer again Figure 4 The AP can send DL to different STA5s during a time gap between UL transmissions on STA4. Similar to Example Scenario 4, this operation can utilize the AP's SBFD capability to ensure that an ongoing non-preemptive UL transmission can be successfully received while the AP's DL transmission exists on a portion of the bandwidth. If successful reception of the non-preemptive UL transmission is not required, the AP can simply send in the DL and can tolerate at least a portion of the ongoing UL transmission being incorrectly received during that DL transmission period.

[0067] Furthermore, it is recommended that the time gap be an integer multiple of the OFDM symbol duration (including GI) to ensure that there is no OFDM inter-symbol interference in the frequency portion during reception at the AP.

[0068] Similarly, in Example Scenario 5, the time gaps between different portions of the UL transmission from STA4 can correspond to integer multiples of the OFDM symbol duration added to the GI. This ensures that there is no inter-OFDM symbol interference across different bandwidth portions during reception at the AP. Furthermore, in this example, preemption can also be supported without affecting coexistence with legacy equipment.

[0069] Example Scenario 6: Partial bandwidth DL or UL preemption during single-user DL or UL transmission

[0070] Although the example above illustrates enabling preemption on only a portion of the channel bandwidth for multi-user transmission (where different users (e.g., stations) are allocated different portions of the bandwidth), enabling preemption on only a portion of the channel bandwidth can also be used for single-user (SU) transmission. Figure 5 A corresponding example is shown. In this example, time gaps are provided only within a portion of the channel bandwidth to enable preemption of SU DL or UL transmissions.

[0071] In this example scenario, an ongoing SU transmission in DL or UL can be preempted to facilitate an urgent DL or UL transmission only within a portion of the channel bandwidth, while the ongoing SU transmission continues continuously over the remaining portion of the channel bandwidth. As an example, this could occur when SU ​​DL or UL transmissions between two devices involve the transmission of independent packets, such as a mixture of continuous and non-preemptible packets on one bandwidth portion and non-contiguous and preemptible packets on another bandwidth portion. These different bandwidth portions could, for example, correspond to non-overlapping subchannels of the wireless channel.

[0072] exist Figure 5In this specific example, four parallel packets are being transmitted or received on different sub-channels of the wireless channel. The fourth packet is split into sub-packets separated by time slots. Preemption can occur during one of these time slots.

[0073] Similarly, in Example Scenario 5, the time gaps between different parts of the UL transmission from STA4 can correspond to integer multiples of the OFDM symbol duration plus the GI, to facilitate the reception of non-preemptive and continuous transmissions.

[0074] Figure 6 A flowchart illustrating a method for controlling wireless transmission in a wireless communication system is shown, which can be used to implement the illustrated concept. Figure 6 The method can be used to implement the illustrated concept in wireless communication devices (e.g., an AP 10 mentioned above or a station 20 mentioned above). The wireless communication system can be based on, for example, wireless local area network (WLAN) technology according to the IEEE 802.11 standard family.

[0075] If a processor-based implementation of a wireless communication device is used, then Figure 6 At least some steps of the method can be executed and / or controlled by one or more processors of a wireless communication device. Such a wireless communication device may also include a memory storing information for implementing the methods described below. Figure 6 The program code of at least some of the functions or steps of the method.

[0076] In step 610, the wireless communication device generates data transmissions based on OFDM, specifically at least a first data transmission and a second data transmission. The wireless communication device can generate data transmissions by segmenting the PPDU into smaller parts. Therefore, the data transmissions can correspond to portions or segments of the PPDU.

[0077] In step 620, the wireless communication device generates one or more time slots for separating data transmission. Therefore, the first data transmission and the second data transmission are separated by time slots. The time slots correspond to integer multiples of the OFDM symbol duration added to GI, and allow preemption of the second data transmission by initiating other transmissions on the wireless channel during the time slot.

[0078] The first data transmission can have a first format, while the second data transmission has a second format that differs from the first format. For example, the second format can define fewer fields for parameter estimation than the first format. Thus, it is possible for the receiver to reuse parameter estimation results from the first transmission for receiving the second transmission.

[0079] The OFDM signals for the first and second data transmissions can be based on IFFT, and the wireless communication device can generate one or more time slots by setting the input of the IFFT to zero.

[0080] In some scenarios, generating data transmissions may include: a wireless communication device sending a first data transmission and a second transmission to a first receiver by applying OFDM in a first bandwidth portion of the wireless channel, and a wireless communication device sending one or more other data transmissions to a second receiver by applying OFDM in a second bandwidth portion of the wireless channel. In this scenario, the wireless communication device can send one or more other data transmissions without time gaps. Figure 4 An example of this scenario is shown.

[0081] The time gap allows the wireless communication device to preempt the second data transmission and initiate a third data transmission from the wireless communication device. The first and second data transmissions can be directed to the first receiver, while the third data transmission is directed to the second receiver. Figure 2A and Figure 4 A corresponding example is shown.

[0082] Additionally, or alternatively, the time gap may allow another wireless communication device to preempt the second data transmission and initiate a fourth data transmission from that device. The fourth data transmission can then be intended to be received by the wireless communication device. In some scenarios, initiating the fourth data transmission may include another wireless communication device starting the fourth data transmission during the time gap, for example, as in... Figure 2B The same applies to the previous example. Alternatively, initiating a fourth data transmission may include another wireless communication device sending a request for scheduling the fourth data transmission during a time gap. Figure 2C A corresponding example is shown.

[0083] In step 630, the wireless communication device can preempt the second data transmission by initiating transmission within the time gap. Transmission within the time gap can be used for the transmission of LL data.

[0084] Figure 7 A flowchart illustrating a method for controlling wireless transmission in a wireless communication system is shown, which can be used to implement the illustrated concept. Figure 7 The method can be used to implement the illustrated concepts in wireless communication devices (e.g., a station or an AP 10 mentioned above). The wireless communication system can be based on, for example, Wireless Local Area Network (WLAN) technology according to the IEEE 802.11 standard family.

[0085] If a processor-based implementation of a wireless communication device is used, then Figure 7At least some steps of the method can be executed and / or controlled by one or more processors of a wireless communication device. Such a wireless communication device may also include a memory storing information for implementing the methods described below. Figure 7 The program code of at least some of the functions or steps of the method.

[0086] In step 710, the wireless communication device receives a first data transmission on a wireless channel based on OFDM. The first data transmission and the second data transmission on the wireless channel are separated by a time gap, which corresponds to an integer multiple of the sum of the OFDM symbol duration and the guard interval, and allows preemption of the second data transmission by initiating other transmissions on the wireless channel during the time gap.

[0087] In step 720, the wireless communication device can preempt the second data transmission by initiating transmission during the time gap. The transmission during the time gap can be used for the transmission of LL data.

[0088] The first data transmission can have a first format, while the second data transmission has a second format different from the first format. For example, the second format can define fewer fields for parameter estimation than the first format. This allows the receiver to reuse parameter estimation results from the first transmission for receiving the second transmission. If the second data transmission is not preempted, the wireless communication device can also receive the second data transmission.

[0089] For receiving the first data transmission and the second data transmission, the wireless communication device can process the first data transmission and the second data transmission based on the same FFT window timing relative to the OFDM symbol.

[0090] The time gap allows a wireless communication device to preempt the second data transmission and initiate a third data transmission from that device. The third data transmission can be intended to be received by another wireless communication device corresponding to the transmitter of the first and second data transmissions, for example, as in... Figure 2B and Figure 2C The same applies to the example. In some scenarios, initiating a third data transmission may involve the wireless communication device starting a third data transmission during a time gap, for example, like in... Figure 2B The same applies to the example above. Alternatively, initiating a third data transmission may involve the wireless communication device sending a request for scheduling the third data transmission during a time gap, for example, as in... Figure 2C The same as in the example.

[0091] Figure 8 A processor-based implementation of the AP 800 is shown. For example... Figure 8 The structure shown can be used to implement the concepts described above. AP 800 may, for example, correspond to one of the AP 10s mentioned above.

[0092] As shown in the figure, AP 800 includes a radio interface 810. The radio interface 810 can be based, for example, on WLAN technology according to the IEEE 802.11 family of standards. However, other wireless technologies, such as LTE or NR, can also be supported. Furthermore, AP 800 is provided with a network interface 820 for connecting to a data network, for example, using a wired connection.

[0093] Furthermore, the AP 800 may include one or more processors 850 coupled to interfaces 810, 820, and a memory 860 coupled to processor(s) 850. As an example, interfaces 810, 820, processor(s) 850, and memory 860 may be coupled via one or more internal bus systems of the AP 800. Memory 860 may include read-only memory (ROM) (e.g., flash ROM), random access memory (RAM) (e.g., dynamic RAM (DRAM) or static RAM (SRAM)), mass storage (e.g., hard disk or solid-state drive), etc. As shown, memory 860 may include software 870 and / or firmware 880. Memory 860 may include appropriately configured program code executed by processor(s) 850 to implement the functions described above for controlling wireless transmissions, such as combining... Figure 6 Methods or combinations Figure 7 The method described therein.

[0094] It should be understood that, such as Figure 8 The structure shown is merely illustrative, and AP 800 may actually include other components, which are not shown for clarity, such as other interfaces or other processors. Furthermore, it should be understood that memory 860 may include additional program code for implementing known functions of the AP in IEEE 802.11 standard-compliant technologies. According to some embodiments, computer programs for implementing the functions of AP 800 may also be provided, for example, in the form of a physical medium storing program code and / or other data to be stored in memory 860, or by making the program code available for download or streaming.

[0095] Figure 9 A processor-based implementation of wireless device 900 is shown. For example... Figure 9 The structure shown can be used to implement the concept described above. Wireless device 900 may, for example, correspond to one of the stations 20 mentioned above.

[0096] As shown in the figure, the wireless communication device 900 includes a radio interface 910. The radio interface 910 may be based, for example, on WLAN technology according to the IEEE 802.11 family of standards. However, it may also support other wireless technologies, such as LTE or NR technologies.

[0097] Furthermore, the wireless device 900 may include one or more processors 950 coupled to the radio interface 910 and a memory 960 coupled to the processor(s) 950. As an example, the radio interface 910, the processor(s) 950, and the memory 960 may be coupled via one or more internal bus systems of the wireless device 900. The memory 960 may include ROM (e.g., flash ROM), RAM (e.g., DRAM or SRAM), mass storage (e.g., hard disk or solid-state drive), etc. As shown, the memory 960 may include software 970 and / or firmware 980. The memory 960 may include appropriately configured program code executed by the processor(s) 950 to implement the functions described above for controlling wireless transmissions, such as combining... Figure 7 The method described therein.

[0098] It should be understood that, such as Figure 9 The structure shown is merely illustrative, and the wireless device 900 may actually include other components, which are not shown for clarity, such as other interfaces or other processors. Furthermore, it should be understood that the memory 960 may include additional program code for implementing known functions of the STA in IEEE 802.11 standard-compliant technologies. According to some embodiments, computer programs for implementing the functions of the wireless device 900 may also be provided, for example, in the form of a physical medium storing program code and / or other data to be stored in the memory 960, or by making the program code available for download or streaming.

[0099] As can be seen, the concepts described above can be used to enable preemption efficiently without adding excessive complexity to existing technologies. They can even simplify receiver processing and / or data transmission formats, for example, by omitting fields used for parameter estimation and related processing. Furthermore, these concepts can be applied to enable preemption only within a portion of the available bandwidth. This can further improve efficiency, as other portions of the bandwidth remain unaffected. Furthermore, this can allow preemption to be enabled only for a portion of the user's MU OFDM transmission, or allow for coexistence with legacy devices that do not support preemption.

[0100] It should be understood that the examples and embodiments described above are merely illustrative and are readily adaptable to various modifications. For example, the illustrated concepts can be applied in conjunction with various wireless technologies, and are not limited to WLAN technology. Furthermore, the illustrated concepts can be applied to various types of data services. Moreover, it should be understood that the above concepts can be implemented by using software of a corresponding design that will be executed by one or more processors of an existing device or apparatus, or by using dedicated device hardware. Furthermore, it should be noted that the illustrated apparatus or apparatus can each be implemented as a single device or a system of multiple interactive devices or modules.

Claims

1. A method for controlling wireless transmission in a wireless communication system, the method comprising: Based on Orthogonal Frequency Division Multiplexing (OFDM), wireless communication equipment (10; (20; 800; 900) Generate the first and second data transmissions on the wireless channel. The first data transmission and the second data transmission are separated by a time gap, which corresponds to an integer multiple of the sum of the OFDM symbol duration and the guard interval, and allows the second data transmission to be preempted by starting other transmissions on the wireless channel during the time gap.

2. The method according to claim 1, wherein The first data transmission has a first format, and the second data transmission has a second format that is different from the first format.

3. The method according to claim 2, wherein The second format defines fewer fields for parameter estimation than the first format.

4. The method according to any one of claims 1 to 3, comprising: The wireless communication device (10); (20; 800; 900) The first data transmission and the second data transmission are generated by segmentation protocol packet data unit (PPDU).

5. The method according to any one of claims 1 to 4, comprising: The wireless communication device (10; 20; 800; 900) generates OFDM signals for the first data transmission and the second data transmission based on Inverse Fast Fourier Transform (IFFT); as well as The wireless communication device (10; 20; 800; 900) generates the time gap by setting the input of the IFFT to zero.

6. The method according to any one of claims 1 to 5, comprising: By applying the OFDM in the first bandwidth portion of the wireless channel, the wireless communication device (10); 20; 800; 900) send the first data transmission and the second data transmission to the first receiver; and By applying the OFDM in the second bandwidth portion of the wireless channel, the wireless communication device (10; 20; 800; 900) transmits one or more other data transmissions to the second receiver.

7. The method according to claim 6, wherein The wireless communication device (10; 20; 800; 900) transmits the one or more other data transmissions without the time interval.

8. The method according to any one of claims 1 to 7, wherein The time gap allows the wireless communication device (10; 20; 800; 900) to preempt the second data transmission and initiate the third data transmission from the wireless communication device (10; 20; 800; 900).

9. The method according to claim 8, wherein The first data transmission and the second data transmission are intended for the first receiver. The third data transmission is intended for the second receiver.

10. The method according to any one of claims 1 to 8, wherein, The time gap allows another wireless communication device (10; 20; 800; 900) to preempt the second data transmission and initiate a fourth data transmission from the other wireless communication device (10; 20; 800; 900).

11. The method according to claim 10, wherein The fourth data transmission is intended to be received by the wireless communication device (10; 20; 800; 900).

12. The method according to claim 11, in, Initiating the fourth data transmission includes: the other wireless communication device (10; 20; 800; 900) starting the fourth data transmission during the time gap.

13. The method according to claim 11, in, Initiating the fourth data transmission includes: the other wireless communication device (10; 20; 800; 900) sending a request for scheduling the fourth data transmission during the time gap.

14. The method according to any one of claims 1 to 13, in, The wireless communication devices (10; 20; 800; 900) are the access points (APs) of the wireless communication system.

15. The method according to any one of claims 1 to 13, in, The wireless communication devices (10; 20; 800; 900) are non-AP stations of the wireless communication system.

16. The method according to any one of claims 1 to 14, in, The wireless communication system is based on wireless local area network technology according to the IEEE 802.11 standard family.

17. A method for controlling wireless transmission in a wireless communication system, the method comprising: Based on Orthogonal Frequency Division Multiplexing (OFDM), wireless communication equipment (10; (20; 800; 900) Receive the first data transmission on the wireless channel. The first data transmission and the second data transmission on the wireless channel are separated by a time gap, which corresponds to an integer multiple of the sum of the OFDM symbol duration and the guard interval, and allows the second data transmission to be preempted by starting other transmissions on the wireless channel during the time gap.

18. The method according to claim 17, in, The first data transmission has a first format, and the second data transmission has a second format that is different from the first format.

19. The method according to claim 18, in, The second format defines fewer fields for parameter estimation than the first format.

20. The method according to any one of claims 17 to 19, comprising: The wireless communication devices (10; 20; 800; 900) process the first data transmission and the second data transmission based on the same Fast Fourier Transform (FFT) window timing relative to the OFDM symbols.

21. The method according to any one of claims 17 to 20, in, The time gap allows the wireless communication device (10; 20; 800; 900) to preempt the second data transmission and initiate the third data transmission from the wireless communication device.

22. The method according to claim 21, in, The third data transmission is intended to be received by another wireless communication device (10; 20; 800; 900) of the transmitter corresponding to the first data transmission and the second data transmission.

23. The method according to claim 22, in, Initiating the third data transmission includes: the wireless communication device (10; 20; 800; 900) starting the third data transmission during the time interval.

24. The method according to claim 23, in, Initiating the third data transmission includes: the wireless communication device (10; 20; 800; 900) sending a request for scheduling the third data transmission during the time interval.

25. The method according to any one of claims 17 to 24, in, The wireless communication devices (10; 20; 800; 900) are the access points (APs) of the wireless communication system.

26. The method according to any one of claims 17 to 24, in, The wireless communication devices (10; 20; 800; 900) are non-AP stations of the wireless communication system.

27. The method according to any one of claims 17 to 26, in, The wireless communication system is based on wireless local area network technology according to the IEEE 802.11 standard family.

28. A wireless communication device (10; 20; 800; 900) for operation in a wireless communication system, said wireless communication device (10; 20; 800; 900) being configured to: Based on Orthogonal Frequency Division Multiplexing (OFDM), the first and second data transmissions are generated on the wireless channel. in, The first data transmission and the second data transmission are separated by a time gap, which corresponds to an integer multiple of the sum of the OFDM symbol duration and the guard interval, and allows the second data transmission to be preempted by starting other transmissions on the wireless channel during the time gap.

29. The wireless communication device (10; 20; 800; 900) according to claim 28. in, The wireless communication devices (10, 11; 800; 900) are configured to perform the method according to any one of claims 2 to 16.

30. The wireless communication device (10; 20; 800; 900) according to claim 28 or 29, comprising: At least one processor (850; 950), and The memory (60; 960) contains program code executable by the at least one processor (850; 950). Thus, the execution of the program code by the at least one processor (850; 950) causes the wireless communication device (10; 20; 800; 900) to perform the method according to any one of claims 1 to 12.

31. A wireless communication device for operation in a wireless communication system, the wireless communication device being configured to: Based on Orthogonal Frequency Division Multiplexing (OFDM), the first data transmission is received on a wireless channel. in, The first data transmission and the second data transmission on the wireless channel are separated by a time gap, which corresponds to an integer multiple of the sum of the OFDM symbol duration and the guard interval, and allows preemption of the second data transmission by starting other transmissions on the wireless channel during the time gap.

32. The wireless communication device (10; 20; 800; 900) according to claim 31. in, The wireless communication device (10; 20; 800; 900) is configured to perform the method according to any one of claims 18 to 27.

33. The wireless communication device (10; 20; 800; 900) according to claim 31 or 32, comprising: At least one processor (850; 950), and Memory (860; 960), which contains program code executable by said at least one processor (850; 950), Thus, the execution of the program code by the at least one processor (850; 950) causes the wireless communication device (10; 20; 800; 900) to perform the method according to any one of claims 18 to 27.

34. A computer program or computer program product comprising program code to be executed by at least one processor (850; 950) of a wireless communication device (10; 20; 800; 900), wherein execution of the program code causes the wireless communication device (10; 20; 800; 900) to perform the method according to any one of claims 1 to 16.

35. A computer program or computer program product comprising program code to be executed by at least one processor (850; 950) of a wireless communication device (10; 20; 800; 900), wherein execution of the program code causes the wireless communication device (10; 20; 800; 900) to perform the method according to any one of claims 18 to 27.

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