COMMUNICATION DEVICE AND METHOD

Abstract

A first communication device configured to communicate with a second communication device, the first communication device comprising: a circuit configured to receive a low latency (LL) indication from the second communication device and / or a third communication device indicating to the first communication device that the first communication device is authorized to transmit second LL information; and to transmit the second LL information to the second communication device during and within a bandwidth of an ongoing transmission of a data unit from the third communication device to the second communication device, the second LL information indicating to the second communication device that the first communication device has LL data to transmit to the second communication device.

Description

[Technical field]

[0001] The present disclosure relates to communication devices and methods, and in particular to communication devices and methods for use in a WLAN in which a second communication device (e.g., an access point (AP)) can communicate with multiple other communication devices (e.g., stations (STAs)). [Background technology]

[0002] Many new applications such as Augmented Reality (AR), Virtual Reality (VR), Remote Surgery, and Smart Manufacturing require strict low latency communication. WLAN networks operate under unlicensed spectrum where channel access cannot be guaranteed or predicted due to interfering devices. In WLAN, if a device wants to transmit data over the wireless medium, it must perform listen-before-talk. If another transmission is detected, the device must set a random backoff counter, wait until the transmission is finished, and attempt another channel access after the counter is over. In addition, WLAN implements a virtual carrier sense mechanism that prevents access during transmission by setting a network allocation vector (NAV) time counter. When a device detects a physical (PHY) protocol data unit (PPDU) being transmitted by another device, it sets its NAV counter for the duration of the ongoing frame exchange and does not allow access to the channel until the current transmit opportunity (TXOP) is over. This means that a long latency can occur between when a low latency station (LL_STA) receives a packet from the upper layer and when it can access the channel.

[0003] The "Background" description provided herein is intended to generally provide a context for the present disclosure. To the extent that it is described in this Background section, the work of the currently named inventors, and aspects of the present specification that may not be admitted as prior art at the time of filing, are not admitted expressly or impliedly as prior art to the present disclosure. Summary of the Invention

[0004] The present invention aims to reduce channel access delay in WLANs. A further aim is to provide a communication device and a communication method, a corresponding computer program, and a non-transitory computer-readable recording medium for implementing the communication method, which allows such a reduction.

[0005] According to one aspect, there is provided a first communication device configured to communicate with a second communication device, said first communication device comprising: - receiving a low latency (LL) indication from the second communication device and / or a third communication device indicating to the first communication device that the first communication device is authorized to transmit second LL information; and - transmitting said second LL information to said second communication device during and within a bandwidth of an ongoing transmission of data units from said third communication device to said second communication device. The present invention includes a circuit configured as follows: The second LL information indicates to the second communications device that the first communications device has LL data to send to the second communications device.

[0006] According to a further aspect, there is provided a second communication device configured to communicate with the first communication device and the third communication device, said second communication device comprising: - transmitting a low latency (LL) indication to the first communication device indicating that transmission of second LL information by the first communication device is permitted during and within the bandwidth of an ongoing transmission of data units from the third communication device to the second communication device; and - receiving the second LL information from the first communication device during and within a bandwidth of an ongoing transmission of data units from the third communication device to the second communication device; The present invention includes a circuit configured as follows: The second LL information indicates to the second communications device that the first communications device has LL data to send to the second communications device.

[0007] According to a further aspect, there is provided a third communication device configured to communicate with the second communication device, said third communication device comprising: - receiving from the second communication device an instruction to transmit a low latency (LL) instruction indicating to the first communication device that the first communication device is authorized to transmit second LL information; and - Send the above LL instructions The present invention includes a circuit configured as follows.

[0008] According to further aspects, there is provided a computer program comprising program means for causing a computer to perform the steps of the methods disclosed herein, when the computer program is run on a computer, and a non-transitory computer readable recording medium storing a computer program product which, when executed by a processor, causes a computer to perform the methods disclosed herein.

[0009] Embodiments are defined in the dependent claims. It is to be understood that the disclosed communication method, the disclosed computer program and the disclosed computer-readable recording medium have further embodiments similar and / or identical to the claimed communication device, as defined in the dependent claims and / or as disclosed herein.

[0010] One aspect of the present disclosure is to create an event indication, e.g., an event indication frame, that may be transmitted by a STA (also referred to herein as a "first communication device") in the same wireless medium during an ongoing data unit (e.g., PPDU) transmission between two other STAs (also referred to herein as a "second communication device" and a "third communication device"). In this way, only a controlled amount of interference is generated that does not interfere with the reception and decoding of the ongoing data unit transmission, but allows the receiving STA to additionally detect the event indication and receive important notifications.

[0011] One embodiment of the present disclosure is directed to low-latency third-party preemption, enabling a low-latency (LL) device to transmit a low-latency indication (also referred to as an "even indication"), e.g., an LL indication frame (LL_IF), that intentionally overlaps with an ongoing PPDU to indicate the presence of LL traffic while not interfering with the reception of the ongoing PPDU transmission. Additionally, a controlled channel access request is provided, enabling a STA to transmit a channel access indication, e.g., a channel access frame, that intentionally overlaps with an ongoing data unit transmission to indicate a channel access request to an AP while not interfering with the reception of the ongoing data unit transmission.

[0012] The preceding paragraphs have been provided by way of general introduction and are not intended to limit the scope of the following claims. The described embodiments, together with further advantages, will be best understood by reference to the following detailed description taken in conjunction with the accompanying drawings, in which: [Brief description of the drawings]

[0013] A more complete understanding of the present disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description, when considered in connection with the accompanying drawings, in which: [Figure 1] FIG. 1 is a diagram illustrating a standard channel access operation. [Diagram 2] FIG. 2 illustrates a general operation according to one embodiment of the present disclosure. [Diagram 3] FIG. 1 illustrates one embodiment of operation when the first and third communication devices are out of range. [Figure 4] FIG. 1 illustrates one embodiment of operation when a first and a third communication device are in range. [Diagram 5] FIG. 2 is an explanatory diagram of power constraints used in setting transmission power. [Figure 6] FIG. 2 illustrates a first embodiment of transmission power selection. [Figure 7] FIG. 2 illustrates a second embodiment of transmission power selection. [Figure 8] FIG. 2 is a diagram illustrating a schematic configuration of an embodiment of a receiver (second communication device) according to the present disclosure. [Figure 9] 11 is a flowchart illustrating a general operation of a first communication device for transmitting second LL information. [Figure 10] FIG. 2 is a schematic diagram illustrating one embodiment of a circuit of a first communication device for constructing second LL information. [Figure 11] 11 is a diagram for explaining an example of generating a sequence representing second LL information. FIG. [Figure 12] FIG. 13 is a diagram for explaining sparse tone mapping of the second LL information. [Figure 13] 11 is a diagram for explaining continuous tone mapping of the second LL information. FIG. [Figure 14] A diagram for explaining reservation and / or indication of resource units. [Figure 15] 1 shows a schematic diagram of an embodiment of a third communication device using long training field (LTF-) based generation of second LL information. [Figure 16] A schematic diagram of one embodiment of a first communication device using LTF-based generation of second LL information is shown. [Figure 17] FIG. 13 is a diagram showing an example of tone mapping when second LL information generation based on LTF is used. [Figure 18] FIG. 2 is a flowchart of one embodiment of a first communication method according to the present disclosure. [Figure 19] 4 shows a flowchart of one embodiment of a second communication method according to the present disclosure. [Figure 20] 13 shows a flowchart of one embodiment of a third communication method according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Referring now to the drawings, in which like reference numbers indicate identical or corresponding parts throughout the several views, FIG. 1 illustrates a standard channel access operation. An LL_STA ("first communication device") that is not part of an ongoing frame exchange between a transmitter (TX_STA; "third communication device") and a receiver (RX_STA or AP; "second communication device") needs to indicate an event (e.g., "LL arrival" indicating the arrival of an LL packet (generally "LL data") from a higher layer) to the RX_STA. However, the LL_STA needs to wait until the current transmit opportunity (TXOP) ends so that it can contend for channel access.

[0015] In the context of this disclosure, the term "LL data" shall be broadly understood as high priority data that needs to be transmitted urgently and / or has very stringent delay requirements (e.g., very low end-to-end delay, jitter). Examples of common LL data include: - Messages that need to be delivered as quickly as possible, such as alert messages sent by authorities in crisis situations, or distress messages from people in dangerous situations (avalanche, fire danger, vehicle accidents, etc.) sent to emergency services, and - Messages with strict latency constraints and need to be delivered within a limited time, such as video streams or control commands (e.g. smart manufacturing, remote surgery, AR / VR applications, etc.), which need to arrive within a specific time window to ensure correct response actions to real-time events, and real-time data processing (vehicle traffic information, environmental information in industrial processes, etc.), where data collected from sensors need to be processed and delivered to a central processing unit within a specific time window to take relevant actions. Therefore, LL data is also called high priority data, and LL information is also called high priority information.

[0016] In the case of traditional look-ahead, the sender of the ongoing data unit (e.g., PPDU) is also the sender that needs to transmit the LL packet, which is not considered in this disclosure. An alternative way to utilize the look-ahead mechanism is to assume that the transmitter can transmit and receive simultaneously on multiple links and therefore can receive the LL indication on another link. However, this requires advanced circuitry at least in the AP and / or LL_STA. Furthermore, the LL_STA needs to access a channel on another link to transmit the LL indication, which may also be occupied. We guarantee here that the TX_STA and LL_STA are non-AP STAs associated with the RX_STA, which is an AP STA. Because the devices communicate on the same frequency channel, simultaneous transmissions from the TX_STA and LL_STA overlap at the AP.

[0017] FIG. 2 illustrates a general operation according to an embodiment of the present disclosure. It shows that the LL_STA sends an overlap packet, shown as LL_IF 12 (i.e., low latency indication frame; also referred to herein as "second LL info") to the RX_STA containing an overlap event indication indicating that the LL_STA has LL traffic to transmit. The LL_STA receives the LL packet arrival notification 11 (also referred to herein as "first LL info") from the upper layer, processes it, and sends the LL_IF. The AP receives the LL_IF and decides what action (if any) to take to enable channel access to the LL_STA. This decision is included in an indication "A" 13 (also referred to herein as "ind A" or "third LL info"), which may be included within the acknowledgement 20 or in a separate frame. The AP can also indicate to the LL_STA an estimated channel access (CA) time until the LL_STA can expect to have channel access (which is not guaranteed) and be able to transmit LL data 21. This helps the LL_STA schedule the next traffic to transmit.

[0018] Since the AP can only take action after an ongoing data unit 22 (e.g. a PPDU consisting of a preamble field and a data field), i.e. an ongoing transmission of a data unit, has finished, the LL_IF can be transmitted at any point in the ongoing PPDU, preferably at any point in the data field, without affecting the channel access delay of the LL_STA. To avoid interference with the interframe space (IFS), the time from LL arrival to the LL boundary (i.e. the end of the ongoing PPDU) should be greater than the LL processing time plus the duration of the LL_IF.

[0019] Operations for enabling prioritized channel access for LL_STAs may be based on trigger frames (TFs) to allow multi-user transmissions (from LL_STAs and TX_STAs) and / or preemption techniques to temporarily stop transmissions of TX_STAs.

[0020] The mechanism for supporting LL_IF in an AP can be configured as follows: It is necessary to ensure that the AP is in receive mode when the LL_IF is transmitted so that the AP can detect the LL_IF. This can be supported in a variety of ways.

[0021] According to the first aspect, the TX_STA and LL_STA do not need to be in range (i.e., the TX_STA and LL_STA may be out of range, but this embodiment also works if they are in range). One embodiment of the operation in such a situation is illustrated in the diagram shown in FIG. 3. The LL_STA cannot directly synchronize to the PHY preamble of the ongoing PPDU. Therefore, the AP may transmit an LL indication, for example adding an indication "B" 14 (also referred to herein as "ind B" or "fourth LL information") to the acknowledgement 23 and / or TF transmitted before the ongoing PPDU 22, where the indication B represents or is included in the LL indication. The indication B may have one or more of the following functions: - indicates that LL_IF transmission is permitted in the next PPDU; - Allows LL_STA to synchronize to ongoing PPDUs; - indicates the type of PPDU in progress, in order to determine the "wait time" for the LL_STA to locate the data field; and - indicates a time window and / or a set of subcarriers (within the data field) over which the LL_IF may be transmitted. Therefore, the LL_STA can synchronously extract such LL_IF assist information to obtain the physical layer (PHY) configuration to be used for LL_IF 12 transmission after switching from RX to TX mode.

[0022] According to the second method, the TX_STA and the LL_STA are in range. One embodiment of the operation in such a situation is shown in FIG. 4. The LL_STA is in range of the TX_STA transmission, allowing synchronization and decoding of the PHY preamble of the ongoing PPDU. To support the transmission of the LL_IF, the AP needs to instruct the TX_STA to transmit an LL indication, for example, adding an indication "C" 15 (also referred to herein as "ind C" or "fifth LL information") to the PHY preamble 24 of the ongoing PPDU 22 to instruct the LL_STA that the LL_IF can overlap in this PPDU, where the indication C represents an LL indication or is included in the LL indication. In this way, the LL_STA can synchronize and extract the LL_IF assist information from the PHY preamble 24, perform fine synchronization with the HE-STF, LTF preamble 25 of the ongoing PPDU 22, and obtain the PHY configuration (i.e., the PHY configuration that the LL_STA uses to transmit the LL_IF 12 after switching from RX mode to TX mode) Additionally, the LL_STA may use the midamble 26 of the ongoing PPDU 22 to resynchronize and regain the PHY configuration for transmitting the LL_IF 12 or another LL_IF.

[0023] It should be noted that both methods shown in Figures 3 and 4 are not mutually exclusive and can be used to complement each other. The LL_IF allow indication can also be made implicit by creating a rule where the AP allows LL_IF transmissions to overlap with frames that have certain characteristics, such as a minimum number of OFDM symbols in the data field, and that do not have control or management frames.

[0024] Indication B (i.e., the fourth LL information) and indication C (i.e., the fifth LL information) represent embodiments of LL indications and have two main purposes: 1) to allow the LL_STA to synchronize with the PPDU transmitted by the TX_STA, and 2) to provide the LL_STA with information to support LL_IF transmission. Another point related to 1) is that the timeline of the transmission is clear. Indication B is preferably transmitted in the frame immediately before the ongoing PPDU is transmitted. The LL_STA synchronizes to the frame containing indication B, and utilizes this frame to synchronize with the ongoing PPDU from the TX_STA, since this transmission should come at a certain time (e.g., SIFS) after indication B. Indication C is preferably transmitted within the ongoing PPDU, which assumes that the LL_STA and TX_STA are in range of each other. Thus, the LL_STA can directly synchronize with the ongoing PPDU.

[0025] In one embodiment, the LL indication may be configured to not only indicate to the LL_STA that transmission of the LL_IF is permitted (which may simply be a single indication bit), but also to indicate that transmission of the LL_IF is permitted during and within the bandwidth of an ongoing transmission of a data unit from the TX_STA to the AP. However, in an embodiment in which the indication only indicates general permission, the timing and bandwidth / frequency band may be pre-determined or agreed upon, i.e., that transmission of the LL_IF is permitted during and within the bandwidth of an ongoing transmission of a data unit from the TX_STA to the AP.

[0026] According to one embodiment, power control is used to manage the amount of interference caused by the LL_IF and the detection probability of the LL_IF itself. This can be done based on the Signal to Interference Ratio (SIR) metric, which evaluates the ratio between the received power level of the TX_STA and the received power level of the LL_STA at the AP. A diagram of the corresponding parameters is shown in Figure 5. This allows the following parameters and settings to be used: Signal to interference ratio:

number

number

number

[0027] The AP shares power control information for LL_IF transmissions to achieve a target SIR within a minimum LL_IF detection margin, which can be selected from modulation and coding scheme (MCS) level, transmit power, and / or received signal strength indicator (RSSI) accuracy for each STA.

[0028] The transmission power is typically controlled with overlapping transmissions to limit interference. Another approach that can be part of the LL_IF design is to spread the energy of the transmission in the time, frequency, and / or spatial domains. In this way, the interference affecting each spatial stream in each subcarrier of each OFDM symbol is reduced. This is described in more detail below.

[0029] Various options exist for sharing power control information to achieve a target SIR. In the following two embodiments using different options are described in more detail.

[0030] In a first embodiment, the power control information is transmitted directly before the ongoing PPDU. A diagram of the corresponding operation 30 is shown in Fig. 6. In a first step 31, the AP sets two target uplink (UL) RSSI values ​​for the TX_STA and the LL_STA based on the target SIR and transmits them to both STAs before the ongoing PPDU. This allows the TX_STA and the LL_STA to set their respective transmission powers to meet the SIR target, i.e. to achieve the target UL RSSI at the AP (steps 32 and 33). The AP also shares the target SIR and the minimum LL_IF detection margin (step 31) so that the LL_STA can adjust its transmission power within an acceptable margin. Furthermore, the AP may transmit an indication B in step 31, which is retrieved by the LL_STA in step 33 to check whether the LL_IF has dropped. Alternatively or additionally, the TX_STA may transmit an indication C in step 32 (or later) as well as an SIR target and a minimum LL_IF detection margin, which can be retrieved by the LL_STA in step 33 (or later) to check whether the LL_IF is allowed and set the transmit power.

[0031] In step 34, an emergency channel access request (from higher layers) arrives at the LL_STA. The TX_STA transmits a PPDU in step 35 and the AP can start decoding the (ongoing) PPDU in step 36. If the LL_STA is within range of the TX_STA, it can use indication C (step 37) to synchronize and extract the PHY preamble of the ongoing PPDU. If the LL_STA is not within range of the TX_STA, it can use indication B for coarse synchronization and counting the waiting time. Furthermore, by checking the time, frequency and power conditions, it can decide to transmit an LL_IF. If it decides to transmit an LL_IF, it sets the PHY configuration in step 38 and transmits the LL_IF. In step 39, the AP detects the LL_IF and takes corresponding measures. For example, it allows the LL_STA to transmit LL data (e.g., by transmitting indication A or corresponding information to the LL_STA) or denies such transmission (e.g., by not transmitting indication A or transmitting corresponding information to the LL_STA).

[0032] In a second embodiment, power control information is transmitted periodically. A diagram of the corresponding operations 40 is shown in Fig. 7. The AP periodically shares (step 41) the following power control information with the LL_STAs: either as part of an acknowledgement or as part of a separate frame: - for TX_STA transmissions: the received power level (at the AP) from the TX_STA transmission in the upcoming PPDU, or the transmit power used by the TX_STA in the upcoming PPDU and the path loss between the TX_STA and the AP; - the transmit power used by the AP in frames containing power control information, allowing the LL_STA to calculate the path loss towards the AP; - Target SIR and minimum margin for LL_IF detection.

[0033] The LL_STA can then (step 42) calculate the SIR at the AP as a function of TX power and calculate the TX power to meet the SIR target. The AP can send an indication B in step 43, which can be obtained in step 44 by the LL_STA to check if LL_IF is allowed. Steps 34 to 39 then follow as described above with respect to Figure 6, but in step 37 the LL_STA additionally calculates the SIR and transmit power to meet the SIR target, i.e. to achieve the target UL RSSI at the AP.

[0034] To perform the LL_IF detection operation at the receiver, the AP needs to know a predefined sequence of complex numbers that identifies the LL_STA, called the LL_IF sequence, and its time-frequency mapping. This sequence is preferably included in the LL_IF by OFDM modulation, overlapping with a specific subcarrier and OFDM symbol of the ongoing PPDU. Thus, the receiver of the AP can perform LL_IF detection after OFDM demodulation, as shown in FIG. 8, which shows a schematic diagram of one embodiment of a receiver 50 (i.e., RX_STA or AP) according to the present disclosure. Details of the LL_IF sequence design and time-frequency mapping are described below with respect to LL_STA processing.

[0035] The receiver operation begins with OFDM demodulation in OFDM demodulator 51 to obtain received complex samples (in the frequency domain) per subcarrier for each OFDM symbol, as shown in Figure 8. Then, a channel equalizer 52 corrects for channel effects (including MIMO processing, if present), and the complex samples are sent to a decoder 53, a self-interference cancellation (SIC) unit 54, and a LL_IF correlator 55. An (optional) buffer 56 stores complex samples from one or more OFDM symbols to obtain a time-frequency grid of complex samples that allows further joint processing of samples spanning OFDM symbols.

[0036] To process the ongoing PPDU, the decoder 53 decodes the codewords contained in the complex samples and transmits a stream of bits for further processing at higher layers. A by-product of the decoder 53 is the bit-wise log-likelihood ratio of each codeword after applying the respective decoding algorithm (e.g., message passing). These log-likelihood ratios are then used by the modulator 57 to obtain full or partial complex samples in the buffered time-frequency grid that correspond to the original transmission of the TX_STA. These samples are then passed to the SIC unit 54 to cancel self-interference of the ongoing PPDU complex samples and to aid in LL_IF detection.

[0037] To detect the LL_IF, LL_IF correlator 55 performs a correlation operation between the known LL_IF sequence and the buffered time-frequency grid samples. The result of this correlation operation is sent to energy detector 58, which indicates whether an LL_IF has been detected when the energy of the correlation operation exceeds a set threshold. An LL_IF detection indication indicates whether an LL_IF has been detected and optionally issues a SIC request to SIC unit 54 if an initial attempt to detect the LL_IF fails. The use of buffer 56 is an optional LL_IF detection since LL_IF correlator 55 does not need to store complex samples but can instead store the results of the correlation operation from previous OFDM symbols.

[0038] FIG. 9 is a flow chart showing a general LL_STA operation 60 for transmitting an LL_IF. To ensure that the AP is in receive mode (step 61), the LL_STA can get the indication B of the previous frame and / or the indication C of the ongoing PPDU. If there is an indication that the transmission of the LL_IF is permitted, as checked in step 62, the LL_STA checks whether there is a higher layer notification to transmit an urgent LL packet (step 63). If yes, the LL_STA sets its PHY parameters and the design of the LL_IF to use based on time, frequency and power conditions (step 64). These conditions protect the ongoing PPDU from LL_IF interference and allow the AP to detect the LL_IF. If these conditions can be met, as checked in step 65, the LL_STA switches to transmit mode (step 66), synchronizes (coarsely) and transmits the LL_IF overlapping with the ongoing PPDU (step 67). If transmission of the LL_IF is not permitted (checked in step 62), or if urgent channel access is not required (checked in step 63), or if the time, frequency and power conditions are not met (checked in step 65), then the LL_IF is not transmitted (step 68). Optionally, the time, frequency and power conditions may be adapted if possible.

[0039] The LL_IF design, time, frequency and power requirements are described in more detail below. An embodiment of an LL_STA circuit 70 for constructing the LL_IF is shown in FIG. 10. The LL_IF sequence generator 71 generates a sequence of complex numbers (e.g., +1, -1, e jΦ , e- jΦ, ...), which can be divided into sections and repeated, with a different phase shift applied to each section by the cyclic repetition unit 72, to obtain the LL_IF sequence. The cyclic repetition helps the AP receiver to detect multiple energy spikes, which can increase the LL_IF detection probability.

[0040] The tone mapper 73 assigns each complex number of the LL_IF sequence to a specific subcarrier and OFDM symbol in the OFDM configuration of the ongoing PPDU. In contrast to normal tone mappers as conventionally used in WLANs, the LL_IF tone mapper 73 leaves most of the subcarriers empty, since the LL_IF sequence is much smaller than the number of subcarriers and OFDM symbols in the data field of the ongoing PPDU. Finally, the mapped symbols are OFDM modulated by the OFDM modulator 74, a (coarse) synchronization is performed and the LL_IF is transmitted by the synchronization and transmission unit 75 so that it overlaps with the data field of the ongoing PPDU.

[0041] An example of LL_IF sequence generation is shown in Figure 11, where a 4x4 Hadamard matrix is ​​multiplied with a row vector of four phase shifts via a Kronecker product. The resulting matrix is ​​4x16. Three LL_IF sequences can be generated, one for the first two rows and two for the third and fourth rows respectively.

[0042] The amount of energy that the LL_IF correlator 55 at the AP receiver 50 can harvest (as shown in FIG. 8) is proportional to the total length of the LL_IF sequence. This length must therefore be greater than or equal to the target SIR multiplied by a minimum detection margin and a predefined scaling (all linear scales). The margin determines the minimum transmit power at the LL_STA and takes into account the gain of SIC and / or MIMO processing at the AP receiver and the power consumption limitations at the LL_STA transmitter. As an example, assume that the target SIR = 2 (i.e., ∼3 dB) and the minimum detection margin is m TX= 2 (i.e., ~3 dB), and if the predefined scaling is 2, the LL_IF sequence must be at least 8. The predefined scaling decouples the transmit power setting and the LL_IF length, allowing more flexibility in designing the LL_IF.

[0043] Figures 12 and 13 show two possible LL_IF tone mapping methods, specifically sparse LL_IF mapping (Figure 12) and contiguous LL_IF mapping (Figure 13). Sparse mapping allows the LL_IF to be spread across multiple subcarriers and OFDM symbols that are not necessarily adjacent. In the example of Figure 12, the LL_IF tones are mapped to the data subcarriers of the ongoing PPDU at equal intervals of one subcarrier each. This provides diversity against channel variations. On the other hand, contiguous mapping as shown in Figure 13 places the LL_IF sequence on adjacent subcarriers and OFDM symbols. This simplifies the detection of the LL_IF at the AP.

[0044] There are several desirable or required conditions for LL_IF design and tone mapping.

[0045] Regulatory conditions (for short control signal transmissions that do not require listen before talk operation) include one or more of the following: - The transmission should be used for the transmission of management and control frames. LL_IF falls into this category. - The number of LL_IFs transmitted by a particular device (e.g., LL_STA) within an observation period of, e.g., 50 ms, must be less than or equal to a predefined number, e.g., 50. - The total (combined) duration of the LL_IFs within an observation period of, e.g., 50 ms, must be less than or equal to a predefined period, e.g., 2500 ms.

[0046] Non-regulatory conditions include one or more of the following: - The transmission of an LL_IF must not exceed the duration of an ongoing PPDU. - The LL_IF bandwidth must not exceed the ongoing PPDU bandwidth. - The LL_IF must be limited to a specific time window and / or subcarrier group (if any) defined by the AP. - The LL_IF transmit power must meet the SIR target and minimum LL_IF detection margin at the AP.

[0047] The following conditions are optional: - The LL_IF tone mapping must not cause coherent interference with adjacent coded bits, which means that it must not overlap with the interleaving operation of binary convolutional codes or the tone mapping of low-density parity-check codes. - The LL_IF must not overlap with the pilot, guard or null subcarriers of an ongoing PPDU. - The LL_IF shall not overlap the PHY preamble of an ongoing PPDU, unless an LTF-based LL_IF is used.

[0048] In general, the AP and LL_STA should know the exact LL_IF sequence and tone mapping used. Therefore, several LL_IF configurations may be standardized and the AP can signal to the LL_STA which configuration to use, e.g., as part of indication B or accompanying the power control information.

[0049] If the TX_STA and LL_STA are in range, the TX_STA can add information to the PHY preamble to assist the LL_STA in transmitting the LL_IF. This is shown in FIG. 14, which shows the reservation and / or indication of resource units (RUs) to assist in transmitting the LL_IF. The TX_STA should include indication C as part of the PHY preamble if instructed by the AP, unless specific conditions are specified, e.g., the ongoing PPDU is a control or management frame, is a low latency traffic, is part of a sounding procedure, etc. The TX_STA can transmit power control information (TX power, SIR target, etc.) to the LL_STA, as shown in FIG. 6 and FIG. 7. The TX_STA can reserve and / or indicate a specific RU, indicated by the dotted line 81, with a low MCS level or empty to tolerate more LL_IF interference. The LL_IF can be transmitted in any OFDM symbol of this RU 81. An indication of reserved RUs can be included in the preamble, indicated by the dotted line 80.

[0050] An alternative approach to designing and transmitting the LL_IF is to overlap it with the Long Training Field (LTF) of the PHY preamble and / or the midamble of the ongoing PPDU. In this case, the design of the LL_IF needs to match the LTF format (e.g., LTF type and guard interval) of the ongoing PPDU. Figures 15 to 17 show an example of LTF-based LL_IF generation. Figure 15 is a schematic diagram of an embodiment of a TX_STA, Figure 16 is a schematic diagram of an embodiment of an LL_STA, and Figure 17 is a diagram showing an example of the corresponding tone mapping. In these figures, index k indicates the tone, index n indicates the high-efficiency (HE-) LTF symbol to transmit, and N STS,r,total denotes the total number of spatial streams from all STAs.

[0051] According to this embodiment, the LL_IF can be mapped to unused rows of the P matrix in the LTF generation. Alternatively, the TX_STA can leave one or more empty LTF symbols where the LL_STA can transmit the LTF-based LL_IF. The transmission of the ongoing PPDU and the LTF-based LL_IF needs to be synchronized, which can be enabled by the mechanism shown in Figure 3. The LTF-based LL_IF should only overlap with the LTF, not with the PHY preamble or data field. However, the LL_STA can also insert a short training field (STF) at the beginning of the LTF-based LL_IF to overlap with the STF of the ongoing PPDU. The inserted STF should be the same as the STF of the ongoing PPDU, but with a slight cyclic diversity shift that can be standardized. The purpose of inserting the overlapping STF is to help the AP receiver to set the automatic gain control taking into account the received LTF-based LL_IF.

[0052] By transmitting the LTF-based LL_IF at low power instead of using the STF, no AGC adjustment is required. The power level can be set in the manner described above (e.g., Fig. 5-7) to target a high SIR. The low-power LTF-based LL_IF can also be detected by the receiving AP because the LTF design provides more spreading gain across the entire PPDU bandwidth.

[0053] According to another option, the TX_STA can transmit an additional LTF symbol after the LTF it transmitted. In this case, the TX_STA should leave a time gap between its LTF and the data field, corresponding to the duration of the additional LTF. This time gap should be smaller than a defined value, e.g. the Preferred Interframe Space (PIFS), to avoid other devices mistaking the channel for a free one.

[0054] The AP, LL_STA and TX_STA should be aware of the use of the LTF-based LL_IF and act accordingly. Therefore, the AP should signal to both the LL_STA and the TX_STA the LTF-based LL_IF design (e.g., P matrix row and / or LTF OFDM symbol) that may be used to overlap with the upcoming PPDU. For the reception of the ongoing PPDU, the AP may process the LTF using the LL_IF correlator and energy detector unit as shown in FIG. 8. The TX_STA may leave at least one empty resource (e.g., P matrix row and / or LTF OFDM symbol) in the LTF of the ongoing PPDU as required by the AP. The LL_STA may design the LTF-based LL_IF with the specifications (e.g., P matrix row and / or LTF OFDM symbol) given by the AP.

[0055] FIG. 18 shows a flow chart of one embodiment of a first communication method 100 of a first communication device (e.g., LL_STA) configured to communicate with a second communication device according to the present disclosure. In a first step 101, a low latency (LL) indication (e.g., indication B or C described above) is received from the second and / or third communication device. The LL indication indicates to the first communication device that the transmission of second LL information by the first communication device is permitted. Preferably, such transmission is permitted during and within the bandwidth of an ongoing transmission of a data unit from the third communication device to the second communication device. In a second step 102, second LL information (e.g., LL_IF notification described above) is transmitted to the second communication device during and within the bandwidth of an ongoing transmission of a data unit from the third communication device to the second communication device, the second LL information indicating to the second communication device that the first communication device has LL data to transmit to the second communication device.

[0056] 19 shows a flowchart of one embodiment of a second communication method 200 of a second communication device (e.g., RX_STA or AP) configured to communicate with a first communication device and a third communication device according to the present disclosure. In a first step 201, an LL indication is transmitted, which indicates to the first communication device that transmission of second LL information by the first communication device is permitted during and within the bandwidth of an ongoing transmission of a data unit from the third communication device to the second communication device. In a second step 202, second LL information is received from the first communication device within the bandwidth of the ongoing transmission of a data unit from the third communication device to the second communication device, which second LL information indicates to the second communication device that the first communication device has LL data to transmit to the second communication device.

[0057] 20 shows a flow chart of one embodiment of a third communication method 300 of a third communication device (e.g., TX_STA) configured to communicate with a second communication device according to the present disclosure. In a first step 301, an instruction to send an LL indication is received from the second communication device. In a second step 302, the LL indication is sent.

[0058] Thus, the foregoing discussion discloses and describes merely exemplary embodiments of the present disclosure. As will be understood by those skilled in the art, the present disclosure may be embodied in other specific forms without departing from its spirit or essential characteristics. Accordingly, the disclosure of the present disclosure, as well as the other claims, are intended to be illustrative rather than limiting on the scope of the present disclosure. The present disclosure defines in part the scope of the preceding claim terms, including readily identifiable variations of the teachings herein, such that the inventive subject matter is not dedicated to the public.

[0059] In the claims, the words "comprising" do not exclude other elements or steps, and the indefinite article "a" does not exclude a plurality. A single element or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0060] To the extent that embodiments of the present disclosure have been described as being implemented, at least in part, by a software-controlled data processing apparatus, it will be understood that a non-transitory machine-readable medium bearing such software, such as an optical disk, a magnetic disk, a semiconductor memory, etc., is also considered to represent an embodiment of the present disclosure. Moreover, such software may be distributed in other forms, such as via the Internet or other wired or wireless telecommunications systems.

[0061] The elements of the devices, apparatuses, and systems disclosed herein may be implemented by corresponding hardware elements and / or software elements, such as suitable circuits or circuits. A circuit is a structural collection of electronic components, including conventional circuit elements, application specific integrated circuits, standard integrated circuits, application specific standard products, and integrated circuits, including field programmable gate arrays. Furthermore, a circuit includes a central processing unit, a graphics processing unit, a microprocessor, which is programmed or configured according to software code. A circuit includes the above hardware that executes software, but does not include pure software. A circuit or circuit may be implemented by a single device or unit, or multiple devices or units, or chipset(s), or processor(s).

[0062] Further embodiments of the disclosed subject matter are listed below. 1. A first communication device configured to communicate with a second communication device, the first communication device comprising: - receiving a low latency (LL) indication from the second communication device and / or a third communication device indicating to the first communication device that the first communication device is authorized to transmit second LL information; and - transmitting the second LL information to the second communication device during and within a bandwidth of an ongoing transmission of data units from the third communication device to the second communication device. The present invention includes a circuit configured as follows: The second LL information indicates to the second communication device that the first communication device has LL data to transmit to the second communication device. A first communication device. 2. The LL indication is configured to indicate to the first communication device that transmission of second LL information by the first communication device is permitted during and within a bandwidth of an ongoing transmission of data units from the third communication device to the second communication device. 2. A first communication device as described in embodiment 1. 3. The circuit is configured to receive third LL information from the second communication device and indicate to the first communication device whether and / or when the first communication device is authorized to transmit the LL data to the second communication device. 13. A first communication device as in any preceding embodiment. 4. The data unit currently being transmitted from the third communication device to the second communication device comprises a preamble field and a data field, and the circuit is configured to transmit the second LL information during the ongoing transmission of the data field. 13. A first communication device as in any preceding embodiment. 5. The circuit is configured to receive first LL information indicating to transmit LL data to the second communication device. 13. A first communication device as in any preceding embodiment. 6. The circuitry is configured to transmit the second LL information at a time such that a time from the arrival of the first LL information to an end of a data field of the data unit transmitted during the ongoing transmission is greater than a duration of the second LL information plus a margin. 13. A first communication device as in any preceding embodiment. 7. The circuitry is configured to transmit the second LL information in a manner that causes low or no interference, or interference below an interference threshold, to the ongoing transmission of the data unit from the third communication device to the second communication device. 13. A first communication device as in any preceding embodiment. 8. The circuit comprises: - modulating a subset of OFDM symbols of the ongoing transmission of the data unit; - modulating a subset of subcarriers of the ongoing transmission of the data unit; and - mapping a subset of spatial streams of the ongoing transmission of the data unit to a steering matrix. and configured to transmit the second LL information by one or more of A first communication device as described in embodiment 7. 9. The circuit comprises: - a target signal-to-interference ratio at the second communication device; - an interference threshold that must not be exceeded by transmission of said second LL information; - a transmit and receive power level of the second communication device; - path loss information regarding path losses between the second communication device and the third communication device and between the second communication device and the first communication device, and a minimum detection margin for the second communication device to detect the second LL information; and controlling a transmit power of the transmission of the second LL information based on one or more of: 13. A first communication device as in any preceding embodiment. 10. The circuit comprises: configured to synchronize to a transmission of a next data unit by the third communication device and / or to decode the content of a fourth LL information transmitted by the second communication device, the fourth LL information being: - the first communication device is permitted to transmit the second LL information during transmission of the next data unit transmitted by the third communication device; - the first communication device is capable of synchronizing to a transmission of the next data unit by the third communication device using the fourth LL information; - the type of the next data unit to be transmitted by the third communication device; and - a time window and / or a series of subcarriers used by the first communication device to transmit the second LL information; to the first communication device. 13. A first communication device as in any preceding embodiment. 11. The circuitry is configured to synchronize to the ongoing transmission of data units by the third communication device and / or decode content of fifth LL information transmitted by the third communication device, the fifth LL information comprising: - the first communication device is permitted to transmit the second LL information during transmission of the data unit transmitted by the third communication device; - the type of the data unit transmitted by the third communications device in the ongoing transmission; and - a time window and / or a series of subcarriers used by the first communication device to transmit the second LL information; to the first communication device. 13. A first communication device as in any preceding embodiment. 12. The circuit comprises: - synchronizing with a previous frame including fourth LL information transmitted by the second communication device, the previous frame being transmitted a predetermined time prior to the ongoing transmission of the data unit transmitted by the third communication device; - synchronizing with the preamble of the ongoing transmission of the data unit transmitted by the third communication device, the preamble including a fifth LL information; and - synchronizing with the preamble of the ongoing transmission of the data unit transmitted by the third communication device after a previous frame including the fourth LL information was received from the second communication device. configured to synchronize with the ongoing transmission of the data unit from the third communication device by one or more of 13. A first communication device as in any preceding embodiment. 13. The circuit comprises: configured to decode the content of a fourth LL information transmitted by the second communication device and / or a fifth LL information transmitted by the third communication device, the fourth LL information and the fifth LL information being: - the first communication device is authorized to transmit the second LL information in the ongoing transmission of a data unit transmitted by the third communication device; - the type of data units transmitted by the third communications device in the ongoing transmission; and - a time window and / or a series of subcarriers used by the first communication device to transmit the second LL information; to the first communication device. A first communication device as described in embodiment 12. 14. The circuit is configured to include an LL sequence for identifying the first communication device in the second LL information, and to map the LL sequence to a predetermined subcarrier in an OFDM symbol for transmitting the second LL information. 13. A first communication device as in any preceding embodiment. 15. The circuit comprises: - Pseudorandom operation, - Hadamard matrix, - Discrete Fourier transform matrix, and a repeating part containing complex numbers generated by a pseudorandom operation, a Hadamard matrix, or a discrete Fourier transform matrix with a given phase shift; and configured to generate the LL sequence as a sequence of one or more complex numbers among A first communication device as described in embodiment 14. 16. The circuit comprises: - a mapping between long training field (LTF) sequences and unused rows of the training matrix, or - transmitting an additional LTF symbol after the LTF symbol transmitted by the third communication device. and generating the LL sequence by one or more of A first communication device as described in embodiment 14. 17. The circuit comprises: - the length of said LL sequence; - generating said LL sequence; - selected subcarriers and OFDM symbols to be transmitted by the third communications device and used for a tone mapping operation within the data unit; - the number of additional LTF symbols; and - a set of unused rows of the training matrix and configured to receive, from the second communication device, configuration information for transmission of the second LL information indicating one or more of: A first communication device as described in embodiment 16. 18. The circuit is configured to map the complex numbers of the LL sequence to selected subcarriers and OFDM symbols of resources used by the third communication device to transmit the data unit, the complex numbers being either continuously spread or sparsely spread across multiple tones with multiple tones spaced apart. A first communication device as described in embodiment 16 or 17. 19. A second communication device configured to communicate with a first communication device and a third communication device, the second communication device comprising: - transmitting a low latency (LL) indication to the first communication device indicating that the first communication device is authorized to transmit second LL information; and - receiving the second LL information from the first communication device during and within a bandwidth of an ongoing transmission of data units from the third communication device to the second communication device; The present invention includes a circuit configured as follows: The second LL information indicates to the second communication device that the first communication device has LL data to transmit to the second communication device. A second communication device. 20. The circuit is configured to transmit third LL information to the first communication device, the third LL information indicating to the first communication device whether and when the first communication device is permitted to transmit the LL data to the second communication device. A second communication device as described in embodiment 19. 21. The circuit is configured to transmit the third LL information as part of an acknowledgement or as a separate frame. A second communication device as described in embodiment 19 or 20. 22. The third LL information indicates whether the third communication device is permitted to transmit data units simultaneously with the transmission of the LL data or whether the third communication device must temporarily stop transmitting data during the transmission of the LL data by the first communication device. A second communication device according to any one of embodiments 19 to 21. 23. The circuit is configured to instruct the third communication device to transmit fourth LL information and / or to transmit fifth LL information, and the fourth LL information and the fifth LL information are: - the first communication device is permitted to transmit the second LL information during the ongoing transmission of a data unit transmitted by the third communication device; - the first communication device is capable of synchronizing to the ongoing transmission of the data unit by the third communication device using the fourth LL information and the fifth LL information; - the type of data units transmitted by the third communication device in the ongoing transmission; and - a time window and / or a series of subcarriers used by the first communication device to transmit the second LL information; to the first communication device. A second communication device according to any one of embodiments 19 to 22. 24. The circuit is configured to instruct the third communication device to transmit the fifth LL information in a preamble field of a transmitted data unit to indicate to the first communication device that transmission of the second LL information is permitted during transmission of the data unit by the third communication device. A second communication device as described in embodiment 23. 25. The circuit comprises: - a target signal-to-interference ratio at the second communication device; - an interference threshold that must not be exceeded by transmission of said second LL information; - a transmit and receive power level of the second communication device; - path loss information regarding a path loss between the second communication device and the third communication device and / or between the second communication device and the first communication device, and a minimum detection margin for the second communication device to detect the second LL information; and controlling a transmit power of the transmission of the second LL information based on one or more of: A second communication device according to any one of embodiments 19 to 24. 26. The circuit comprises: - the length of said LL sequence; - generating said LL sequence; - selected subcarriers and OFDM symbols to be transmitted by the third communications device and used for a tone mapping operation within the data unit; - the number of additional LTF symbols; and - a set of unused rows of the training matrix and configured to transmit to the first communication device configuration information for the transmission of the second LL information indicating one or more of: A second communication device according to any one of embodiments 19 to 25. 27. The circuitry is configured to detect the second LL information using knowledge of an LL sequence used by the first communication device to identify the first communication device and knowledge of a mapping of the LL sequence to predetermined subcarriers within an OFDM symbol used by the first communication device to transmit the second LL information. A second communication device according to any one of embodiments 19 to 26. 28. The circuit is configured to detect the second LL information by additional use of a self-interference cancellation operation based on a likelihood ratio of bits of the data unit received from the third communication device. A second communication device as described in embodiment 27. 29. The circuitry is configured to detect the second LL information by detecting the data unit received from the third communication device, subtracting the detected data unit from a received signal, and detecting the second LL information from a remaining signal. A second communication device as described in embodiment 27 or 28. 30. A third communication device configured to communicate with a second communication device, the third communication device comprising: - receiving an instruction from the second communication device to transmit a low latency (LL) indication indicating to the first communication device that the first communication device is authorized to transmit second LL information; and - Send the LL instruction The circuit is configured as follows: A third communication device. 31. The circuit is configured to receive an instruction to transmit fifth low-latency (LL) information from the second communication device, the fifth LL information being: - the first communications device is permitted to transmit the second LL information during the ongoing transmission of the data unit transmitted by the third communications device (wherein the second LL information indicates to the second communications device that the first communications device has LL data to transmit to the second communications device); - the first communication device is capable of synchronizing to the ongoing transmission of the data unit by the third communication device using the fifth LL information; - a type of data unit transmitted by the third communications device in the ongoing transmission; - a time window and / or a series of subcarriers used by the first communication device to transmit the second LL information; - transmitting said fifth LL information; and - transmitting a data unit to the second communication device. to the first communication device. A third communication device as described in embodiment 30. 32. The circuit comprises: - the type of information contained in the data fields of the Data Unit; - the fifth LL information, - power control information for enabling the first communication device to control a transmission power for transmitting the second LL information; and - a location of a resource unit that the first communication device should use to transmit the second LL information; in a preamble field of the data unit to be transmitted. A third communication device as described in embodiment 30 or 31. 33. The circuit comprises: - receiving third LL information from the second communication device; and - transmitting a data unit simultaneously with a transmission of LL data or stopping a data transmission during a transmission of the LL data by the first communication device. It is structured as follows: The third LL information indicates to the third communication device whether transmission of data units is permitted simultaneously with the transmission of the LL data or whether the third communication device must temporarily stop transmitting data during the transmission of the LL data by the first communication device. A third communication device as described in embodiment 30, 31 or 32. 34. A first communication method for a first communication device configured to communicate with a second communication device, comprising: - receiving a low latency (LL) indication from the second and / or third communication devices, the low latency (LL) indication indicating to the first communication device that the first communication device is authorized to transmit second LL information; - transmitting the second LL information to the second communication device during and within a bandwidth of an ongoing transmission of data units from the third communication device to the second communication device; Including, The second LL information indicates to the second communication device that the first communication device has LL data to transmit to the second communication device. The first communication method. 35. A second communication method for a second communication device configured to communicate with a first communication device and a third communication device, comprising: - transmitting a low latency (LL) indication to the first communication device indicating that the first communication device is permitted to transmit second LL information during and within a bandwidth of an ongoing transmission of data units from the third communication device to the second communication device; - receiving the second LL information from the first communication device during and within a bandwidth of an ongoing transmission of data units from the third communication device to the second communication device; Including, The second LL information indicates to the second communication device that the first communication device has LL data to transmit to the second communication device. The second communication method. 36. A third communication method for a third communication device configured to communicate with a second communication device, comprising: - receiving an instruction from the second communication device to transmit a low latency (LL) indication indicating to the first communication device that the first communication device is authorized to transmit second LL information; - transmitting said LL indication; Includes The third communication method. 37. A non-transitory computer-readable recording medium storing a computer program product that, when executed by a processor, causes the method according to embodiment 34, 35 or 36 to be performed. 38. A computer program comprising program code means for causing a computer to carry out the steps of the method according to embodiment 34, 35 or 36, when the computer program is run on a computer.

Claims

1. A first communication device configured to communicate with a second communication device, the first communication device comprising: - receiving a low latency (LL) indication from the second communication device and / or a third communication device indicating to the first communication device that the first communication device is authorized to transmit second LL information; and - transmitting the second LL information to the second communication device during and within a bandwidth of an ongoing transmission of data units from the third communication device to the second communication device. The present invention includes a circuit configured as follows: The second LL information indicates to the second communication device that the first communication device has LL data to transmit to the second communication device. A first communication device.

2. The LL indication is configured to indicate to the first communication device that transmission of second LL information by the first communication device is permitted during and within a bandwidth of an ongoing transmission of data units from the third communication device to the second communication device. A first communication device as claimed in claim 1 .

3. The circuitry is configured to transmit the second LL information in a manner that causes low or no interference, or interference below an interference threshold, to the ongoing transmission of the data unit from the third communication device to the second communication device. A first communication device as claimed in claim 1 .

4. The circuit comprises: - modulating a subset of OFDM symbols of the ongoing transmission of the data unit; - modulating a subset of subcarriers of the ongoing transmission of the data unit; and - mapping a subset of spatial streams of the ongoing transmission of the data unit to a steering matrix. and configured to transmit the second LL information by one or more of A first communication device according to claim 3 .

5. The circuit comprises: - a target signal-to-interference ratio at the second communication device; - an interference threshold that must not be exceeded by transmission of said second LL information; - a transmit and receive power level of the second communication device; - path loss information regarding path losses between the second communication device and the third communication device and between the second communication device and the first communication device, and a minimum detection margin for the second communication device to detect the second LL information; and controlling a transmit power of the transmission of the second LL information based on one or more of: A first communication device as claimed in claim 1 .

6. The circuit comprises: i) configured to synchronize to a transmission of a next data unit by the third communication device and / or to decode the content of a fourth LL information transmitted by the second communication device, the fourth LL information being - the first communication device is permitted to transmit the second LL information during transmission of the next data unit transmitted by the third communication device; - the first communication device is capable of synchronizing to a transmission of the next data unit by the third communication device using the fourth LL information; - the type of the next data unit to be transmitted by the third communication device; and - a time window and / or a series of subcarriers used by the first communication device to transmit the second LL information; to the first communication device; and / or ii) the circuitry is configured to synchronize to the ongoing transmission of data units by the third communication device and / or to decode content of fifth LL information transmitted by the third communication device, the fifth LL information comprising: - the first communication device is permitted to transmit the second LL information during transmission of the data unit transmitted by the third communication device; - the type of the data unit transmitted by the third communications device in the ongoing transmission; and - a time window and / or a series of subcarriers used by the first communication device to transmit the second LL information; to the first communication device; and / or iii) the circuit comprises: - synchronizing with a previous frame including fourth LL information transmitted by the second communication device, the previous frame being transmitted a predetermined time prior to the ongoing transmission of the data unit transmitted by the third communication device; - synchronizing with the preamble of the ongoing transmission of the data unit transmitted by the third communication device including fifth LL information; and - synchronizing with the preamble of the ongoing transmission of the data unit transmitted by the third communication device after a previous frame including the fourth LL information was received from the second communication device. configured to synchronize with the ongoing transmission of the data unit from the third communication device by one or more of A first communication device as claimed in claim 1 .

7. The circuit is configured to include an LL sequence for identifying the first communication device in the second LL information, and to map the LL sequence to a predetermined subcarrier within an OFDM symbol for transmitting the second LL information. A first communication device as claimed in claim 1 .

8. A second communication device configured to communicate with the first communication device and a third communication device, the second communication device comprising: - transmitting a low latency (LL) indication to the first communication device indicating that the first communication device is authorized to transmit second LL information; and - receiving the second LL information from the first communication device during and within a bandwidth of an ongoing transmission of data units from the third communication device to the second communication device; The present invention includes a circuit configured as follows: The second LL information indicates to the second communication device that the first communication device has LL data to transmit to the second communication device. A second communication device.

9. the circuitry is configured to transmit third LL information to the first communication device, the third LL information indicating to the first communication device whether and when the first communication device is permitted to transmit the LL data to the second communication device; and / or The circuitry is configured to transmit the third LL information as part of an acknowledgment or as a separate frame. A second communication device according to claim 8.

10. The circuit comprises: - a target signal-to-interference ratio at the second communication device; - an interference threshold that must not be exceeded by transmission of said second LL information; - a transmit and receive power level of the second communication device; - path loss information regarding a path loss between the second communication device and the third communication device and / or between the second communication device and the first communication device, and a minimum detection margin for the second communication device to detect the second LL information; and controlling a transmit power of the transmission of the second LL information based on one or more of: A second communication device according to claim 8.

11. The circuitry is configured to detect the second LL information using knowledge of an LL sequence used by the first communication device to identify the first communication device and knowledge of a mapping of the LL sequence to predetermined subcarriers within an OFDM symbol used by the first communication device to transmit the second LL information. A second communication device according to claim 8.

12. the circuit is configured to detect the second LL information by additional use of a self-interference cancellation operation based on a likelihood ratio of bits of the data unit received from the third communication device; and / or The circuitry is configured to detect the second LL information by detecting the data unit received from the third communication device, subtracting the detected data unit from a received signal, and detecting the second LL information from a remaining signal. A second communication device according to claim 11.

13. a third communication device configured to communicate with the second communication device, the third communication device comprising: - receiving an instruction from the second communication device to transmit a low latency (LL) indication indicating to the first communication device that the first communication device is authorized to transmit second LL information; and - Send the LL instruction The circuit is configured as follows: A third communication device.

14. The circuitry is configured to receive an instruction from the second communication device to transmit fifth low latency (LL) information, the fifth LL information comprising: - the first communication device is permitted to transmit the second LL information during the ongoing transmission of the data unit transmitted by the third communication device, where the second LL information indicates to the second communication device that the first communication device has LL data to transmit to the second communication device; - the first communication device is capable of synchronizing to the ongoing transmission of the data unit by the third communication device using the fifth LL information; - a type of data unit transmitted by the third communication device in the ongoing transmission; - a time window and / or a series of subcarriers used by the first communication device to transmit the second LL information; - transmitting said fifth LL information; and - transmitting a data unit to the second communication device. to the first communication device. A third communication device according to claim 13.

15. The circuit comprises: - the type of information contained in the data fields of the Data Unit; - the fifth LL information, - power control information for enabling the first communication device to control a transmission power for transmitting the second LL information; and - a location of a resource unit that the first communication device should use to transmit the second LL information; in a preamble field of the data unit to be transmitted. A third communication device according to claim 13.

16. The circuit comprises: - receiving third LL information from the second communication device; and - transmitting a data unit simultaneously with a transmission of LL data or stopping a data transmission during a transmission of the LL data by the first communication device. It is structured as follows: The third LL information indicates to the third communication device whether transmission of data units is permitted simultaneously with the transmission of the LL data or whether the third communication device must temporarily stop transmitting data during the transmission of the LL data by the first communication device. A third communication device according to claim 13.

17. 1. A first communication method for a first communication device configured to communicate with a second communication device, comprising: - receiving a low latency (LL) indication from the second and / or third communication device, the low latency (LL) indication indicating to the first communication device that the first communication device is authorized to transmit second LL information; - transmitting the second LL information to the second communication device during and within a bandwidth of an ongoing transmission of data units from the third communication device to the second communication device; Including, The second LL information indicates to the second communication device that the first communication device has LL data to transmit to the second communication device. The first communication method.

18. A second communication method for a second communication device configured to communicate with a first communication device and a third communication device, comprising: - transmitting a low latency (LL) indication to the first communication device indicating that the first communication device is authorized to transmit second LL information during and within a bandwidth of an ongoing transmission of data units from the third communication device to the second communication device; - receiving the second LL information from the first communication device during and within a bandwidth of an ongoing transmission of data units from the third communication device to the second communication device; Including, The second LL information indicates to the second communication device that the first communication device has LL data to transmit to the second communication device. The second communication method.

19. A third communication method for a third communication device configured to communicate with a second communication device, the method comprising: - receiving an instruction from the second communication device to transmit a low latency (LL) indication indicating to the first communication device that the first communication device is authorized to transmit second LL information; - transmitting said LL indication; Includes The third communication method.

20. A non-transitory computer readable storage medium storing a computer program product which, when executed by a processor, causes the method of claim 17, 18 or 19 to be performed.

Images