Direct link resource release mechanism in multi-user TXOP

Abstract

An access point, AP, is granted a transmission opportunity to schedule multi-user transmissions with non-AP stations. The AP can provide resource units for direct link transmissions to peer stations within the TxOP. The DiL resource unit allocation duration. However, the duration can not match the peer demand and be too long. Bandwidth is lost. To feed back the resource units to the AP, the peer stations send a resource release frame such as a QoS null frame to the AP on the allocated DiL resource units when the DiL transmission is completed. The AP can then reuse the saved time to provide more transmission time to other stations within the TxOP.

Description

Technical Field

[0001] This invention generally relates to wireless communication. Background Technology

[0002] Wireless communication networks are widely deployed to provide various communication services, such as voice, video, packet data, messaging, and broadcasting. These wireless networks can be multiple access networks capable of supporting multiple users by sharing available network resources. Examples of such multiple access networks include Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, Frequency Division Multiple Access (FDMA) networks, Orthogonal FDMA (OFDMA) networks, and Single Carrier FDMA (SC-FDMA) networks.

[0003] The 802.11 family of standards, adopted by the Institute of Electrical and Electronics Engineers (IEEE-RTM), provides a large number of mechanisms for wireless communication between stations.

[0004] To address the increased bandwidth and reduced latency requirements of wireless communication systems in high-density environments, multi-user (MU) schemes are being developed to allow a single access point (AP) to schedule MU transmissions within a wireless network, i.e., multiple simultaneous transmissions relative to non-AP stations. For example, IEEE adopted one such MU scheme in draft version 6.0 (D6.0) of the 802.11ax standard in November 2019.

[0005] The 802.11ax MU transmission scheme used is unsuitable for high-bandwidth communication services, such as video-based services like gaming, virtual reality, and streaming applications. This is because all communication passes through the access point (AP), doubling the airtime and increasing the number of media access points (and thus increasing media access time).

[0006] The 802.11 network protocol's single-user (SU) scheme allows for direct link (DiL, also known as point-to-point (P2P) transmission) where the 48-bit IEEE MAC address of the destination station is used to address data (MAC) frames.

[0007] However, the SU and MU schemes directly compete with each other for access to the wireless medium (for the MU scheme, this is done by the AP; for the SU scheme, it is done by non-AP stations). In high-density environments, this competition generates a large number of unwanted collisions, thereby reducing latency and overall useful data throughput. Summary of the Invention

[0008] To overcome some of the aforementioned problems, the inventors considered integrating DiL / P2P communication under the global policy of AP scheduling during the authorized transmission opportunity TxOP.

[0009] In this context, the present invention first provides a communication method in a wireless network, comprising: at a peer station,

[0010] The peer station receives a trigger frame from the access point (AP), which provides the peer with resource units for direct link transmission (DiL transmission) during the TxOP period, which is authorized to the AP.

[0011] DiL transmission with another peer station on the provided resource unit, and

[0012] Upon completion of the DiL transmission, a resource release frame is sent to the AP on the provided resource unit.

[0013] The present invention also provides a communication method in a wireless network, comprising: at an access point (AP), during an authorized transmission opportunity (TxOP),

[0014] A trigger frame is sent to the peer station, the trigger frame providing resource units for direct link transmission, i.e., DiL transmission, and

[0015] Receive a resource release frame from one of the peer stations on the provided resource unit.

[0016] Therefore, in response to a resource release frame, the AP can resume transmission on the resource unit, for example, by performing a MU DL transmission or triggering a MU UL transmission.

[0017] In the proposed scheme, the AP serves as the central point for scheduling resource units at the BSS level within the authorized TxOP. Resource units can be used for downlink (i.e., from the AP), uplink (i.e., to the AP), and DiL transmissions. Therefore, resource units can be provided to peer stations for DiL.

[0018] A peer manages DiL resource units, for example, by offloading or time-sharing resources with the corresponding peer (with which the managing peer has an established direct link session). This is efficient because the managing peer typically has knowledge of the other peer's communication needs.

[0019] This two-level control of resource units, especially for direct link communication, results in efficient and simple management of resources.

[0020] Furthermore, the resource release frame is a dedicated message terminating DiL transmission, thus releasing the resource unit used for DiL transmission. The AP restores the resource's usage before the initial end of resource unit allocation and can immediately use the resource (after SIFS), thereby avoiding unnecessary padding of the signal on the resource unit during all resource unit allocations. Therefore, bandwidth utilization of the wireless network is improved.

[0021] Relatedly, the present invention also provides a wireless communication device including at least one microprocessor configured to perform the steps of any of the methods described above.

[0022] Optional features of embodiments of the invention are defined in the appended claims. Some of these features will be described below with reference to methods, and these can be converted into apparatus features.

[0023] In some embodiments, a predefined duration for the resource unit is provided, and a resource release frame is sent (by the peer station) or received (by the AP) before the predefined duration ends or expires. Preferably, the resource release frame is sent at SIFS after the last packet of the DiL transmission. The DiL transmission includes all packets exchanged between the peer stations, including data, but also their acknowledgments. Therefore, the resource release frame can be sent at SIFS after the data packet, or at SIFS after the acknowledgment (if any).

[0024] Depending on the optional features, the method at the AP may also include setting a network allocation vector (NAV) to delay the AP's media access until the end of a predefined duration.

[0025] According to another optional feature, at the peer station, the method further includes: in response to receiving the trigger frame, sending a resource acknowledgment frame to the AP before initiating a DiL transmission with another peer station. Relatedly, at the AP, the method further includes: in response to receiving the trigger frame, receiving a resource acknowledgment frame from the peer station. In this case, the AP can set its NAV in response to receiving the resource acknowledgment frame. This advantageously provides better control over the allocated resource units.

[0026] It should be noted that variations in the use of resource confirmation frames can involve the energy detected on the allocated DiL resource units.

[0027] In some embodiments, the method further includes receiving or transmitting one or more trigger frames from the AP during an authorized TxOP, the trigger frames triggering multi-user transmissions, i.e., MU transmissions. This defines a cascading scheme for MU transmissions managed by the AP, where the benefits of combining the present invention with DiL opportunities are significant.

[0028] In some embodiments, the resource release frame is a single-user data frame, i.e., a SU data frame. The SU frame format is defined in 802.11.

[0029] In a particular embodiment, the resource release frame is an 802.11 QoS empty frame. This advantageously limits the bandwidth used to terminate DiL transmissions and release DiL resource units.

[0030] Alternatively, the resource release frame is an enhanced 802.11 QoS empty frame that includes a buffer status report (BSR). This approach advantageously provides the AP with useful information to schedule new transmissions for the peer that sent the resource release frame.

[0031] Specifically, a BSR may include the peer's DiL requirements. Of course, a BSR may also include the peer's requirements regarding UL transmissions.

[0032] In a particular embodiment, the resource release frame is a unicast 802.11 CF-End frame addressed to the AP. This advantageously limits the bandwidth used. Furthermore, using unicast addressing (instead of the broadcast addressing required for CF-End in known techniques) ensures that only the AP resets its NAV.

[0033] Another aspect of the invention relates to a non-transitory computer-readable medium storing a program that, when executed by a microprocessor or computer system in a wireless device, causes the wireless device to perform any of the methods defined above.

[0034] At least a portion of the method according to the invention can be implemented by a computer. Therefore, the invention can take the form of a completely hardware embodiment, a completely software embodiment (including firmware, resident software, microcode, etc.), or an embodiment combining software and hardware aspects, all of which are generally referred to herein as “circuit,” “module,” or “system.” Furthermore, the invention can take the form of a computer program product embodied in any tangible medium having computer-usable program code embodied in the medium.

[0035] Because this invention can be implemented in software, it can be embodied as computer-readable code provided to a programmable device on any suitable carrier medium. Tangible carrier media may include storage media such as hard disk drives, magnetic tape devices, or solid-state storage devices. Transient carrier media may include signals such as electrical signals, electronic signals, optical signals, acoustic signals, magnetic signals, or electromagnetic signals (e.g., microwave or RF signals). Attached Figure Description

[0036] Embodiments of the invention will now be described by way of example only and with reference to the following figures, in which:

[0037] Figure 1 A typical 802.11 network environment in which embodiments of the present invention can be implemented is illustrated;

[0038] Figure 2 This illustrates an exemplary scenario for the use of TxOPs authorized to an AP;

[0039] Figure 3 Examples of implementing the present invention are illustrated. Figure 2Exemplary scenarios;

[0040] Figure 3a Examples Figure 3 Variations;

[0041] Figure 4 The general steps of implementing the invention at the AP are illustrated using a flowchart;

[0042] Figure 5a and 5b A flowchart illustrates the general steps at the peer station in a DiL transmission;

[0043] Figure 6a A schematic diagram of a communication device according to an embodiment of the present invention is shown; and

[0044] Figure 6b A schematic representation of a wireless communication device according to an embodiment of the present invention is shown. Detailed Implementation

[0045] The techniques described herein can be used in various broadband wireless communication systems, including communication systems based on orthogonal multiplexing schemes. Examples of such communication systems include Space Division Multiple Access (SDMA) systems, Time Division Multiple Access (TDMA) systems, Orthogonal Frequency Division Multiple Access (OFDMA) systems, and Single-Carrier Frequency Division Multiple Access (SC-FDMA) systems. SDMA systems can utilize sufficiently different directions to simultaneously transmit data belonging to multiple user terminals (i.e., wireless devices or stations). TDMA systems can allow multiple user terminals to share the same frequency channel by dividing the transmitted signal into different time slots or resource units, where each time slot is allocated to a different user terminal. OFDMA systems use Orthogonal Frequency Division Multiplexing (OFDM), a modulation technique that divides the entire system bandwidth into multiple orthogonal subcarriers or resource units. These subcarriers can also be called frequency modulation, inter-cells, etc. Using OFDM, data can be independently modulated onto each subcarrier. SC-FDMA systems can use interleaved FDMA (IFDMA) to transmit on subcarriers distributed across the system bandwidth, use localized FDMA (LFDMA) to transmit on blocks of adjacent subcarriers, or use enhanced FDMA (EFDMA) to transmit on multiple blocks of adjacent subcarriers.

[0046] The teachings herein may be incorporated into (e.g., implemented within or by various devices, such as stations) various devices. In some respects, a wireless device or station implemented according to the teachings herein may include an access point (so-called AP) or a non-access point (so-called non-AP station or STA).

[0047] An AP may include, be implemented as, or be referred to as a Node B, Radio Network Controller (“RNC”), Evolved Node B (eNB), 5G Next Generation Base Station (gNB), Base Station Controller (“BSC”), Base Transceiver Station (“BTS”), Base Station (“BS”), Transceiver Function (“TF”), Radio Router, Radio Transceiver, Basic Service Set (“BSS”), Extended Service Set (“ESS”), Radio Base Station (“RBS”), or some other term.

[0048] Non-AP stations may include, be implemented as, or be referred to as subscriber stations, subscriber units, mobile stations (MS), remote stations, remote terminals, user terminals (UTs), user agents, user devices, user equipment (UEs), user stations, or some other terminology. In some implementations, an STA may include a cellular phone, a cordless phone, a Session Initiation Protocol (“SIP”) phone, a Wireless Local Loop (“WLL”) station, a personal digital assistant (“PDA”), a handheld device with wireless connectivity, or some other suitable processing device connected to a wireless modem. Thus, one or more aspects taught herein may be incorporated into telephones (e.g., cellular phones or smartphones), computers (e.g., laptop computers), tablets, portable communication devices, portable computing devices (e.g., personal data assistants), entertainment devices (e.g., music or video devices or satellite radios), Global Positioning System (GPS) devices, or any other suitable device configured to communicate via wireless or wired media. In some aspects, a non-AP station may be a wireless node. Such a wireless node may provide connectivity to or to a network (e.g., a wide area network such as the Internet or cellular networks) via wired or wireless communication links.

[0049] Figure 1 An exemplary communication system is illustrated, in which several communication stations 101-107, 110 exchange data frames on a radio transmission channel 100 of a wireless local area network (WLAN) under the management of a central station or access point (AP) 110 (also considered a station of the network). The radio transmission channel 100 is defined by an operating frequency band consisting of a single channel or multiple channels forming a composite channel. The AP 110 and the associated non-AP stations 101-107 may represent a Basic Service Set (BSS) or an Extended Service Set (ESS).

[0050] Two non-AP stations 102 and 103 can also communicate directly via a direct wireless link (DiL for direct links), regardless of whether they belong to the same BSS or ESS. In a variant, direct communication between non-AP stations can be achieved without an access point (called ad-hoc mode). For example, the WiFi-Direct standard allows devices to communicate directly over 802.11 wireless media without any AP.

[0051] An exemplary scenario of direct communication corresponding to today's growing trend is the existence of peer-to-peer (P2P) transmissions between non-AP stations sharing the same primary channel, regardless of whether they originate from the same BSS or ESS. Technologies supporting P2P transmissions between non-AP STAs not associated with the same BSS / ESS or without a BSS include, in addition to WiFi-Direct, WiFi-Miracast (RTM) and wireless display scenarios. Other technologies supporting P2P transmissions within a BSS / ESS include Direct Link Setup (DLS) and Tunneled Direct Link Setup (TDLS). Even though P2P streams are typically not numerous, the amount of data per stream (typically low-compressed video ranging from 1080p60 to 8K UHD resolution) is often significant.

[0052] Each non-AP station 101-107 registers with AP 110 during the association process, whereby the AP assigns a specific association identifier (AID) to the requesting non-AP station. For example, the AID is a 16-bit value that uniquely identifies a non-AP station.

[0053] Stations 101-107 and 110 can compete with each other using EDCA (Enhanced Distributed Channel Access) to access radio medium 100 in order to be granted a transmission opportunity (TXOP) and then transmit (single-user, SU) data frames. Stations can also use a multi-user (MU) scheme, where a single station (typically AP 110) schedules MU transmissions relative to other stations during its authorized TXOP in the wireless network, i.e., multiple simultaneous transmissions. This MU scheme is used as an implementation of the multi-user uplink and downlink OFDMA (MU UL and DLOFDMA) procedure, for example, in the IEEE 802.11ax amendment standard. Due to the MU characteristics, non-AP stations have the opportunity to gain access to the radio medium via two access schemes: the MU scheme and the traditional Enhanced Distributed Channel Access (EDCA (single-user)) scheme.

[0054] During MU DL transmissions on licensed communication channels, the AP performs multiple simultaneous basic transmissions to various non-AP stations via so-called Resource Units (RUs). As an example, based on Orthogonal Frequency Division Multiple Access (OFDMA) technology, a Resource Unit divides the communication channels of a wireless network in the frequency domain. The allocation of non-AP stations is signaled to the RUs at the beginning of the MU downlink frame by providing each RU with an Association Identifier (AID) for the non-AP station (obtained individually by the station during its association with the AP) defined in the transmission opportunity.

[0055] During MU UL transmission, various non-AP stations can simultaneously transmit data to the AP on resource units forming the communication channel. To control MU UL transmissions by non-AP stations, the AP previously sends a control frame (called a trigger frame (TF)). The trigger frame uses the 16-bit Association Identifier (AID) assigned to the non-AP station when registering with the AP and / or uses a reserved AID specifying a group of non-AP stations to assign resource units to non-AP stations within the same BSS. The TF also defines the start and length of MU UL transmissions by non-AP stations.

[0056] The variant that triggers UL transmission relies on the use of a TRS (Trigger Response Scheduler) control subfield. Such a TRS control subfield is added to the DL data frame (MU DL transmission) sent by the AP to a non-AP station on a resource unit to provide the receiving non-AP station with resource unit allocation for subsequent MU UL transmissions. Each TRS subfield allocates only a single resource unit (and also provides transmission parameters) for the receiving non-AP station receiving the DL data frame.

[0057] Figure 2 An exemplary scenario illustrating the use of TxOP authorized to an AP is presented. In this scenario, the AP provides a cascade sequence of various transports, including uplink (UL), downlink (DL), and / or DiL transports.

[0058] The 802.11ax revision introduced the MU concatenation mechanism to enable rapid alternation between uplink (UL) and downlink (DL) data transmission. The principle is to alternate between MU DL transmissions and MU UL transmissions during a single TXOP won by the AP.

[0059] This mechanism provides low-latency transmission for interactive applications, gives the AP more flexibility in scheduling non-AP stations, and is also used in the range of TWT (Target Wake-up Time) to schedule different non-AP stations in power-saving modes (usually sleep) that are negotiating power-saving contracts with the AP on a time-based basis.

[0060] In all these cases, the AP initiates the cascading sequence by sending one or more trigger frames 200 (MU PPDU). The trigger frame 200 can be simply an 802.11 trigger frame, or it can be a DL data frame (MSDU) including a Trigger Response Scheduler (TRS) control subfield (in which case several trigger frames are sent to the corresponding receiving non-AP station). These frames provide the non-AP station with the allocation of one or more resource units to form a communication channel.

[0061] The trigger frame is broadcast to all non-AP stations, while individual DL data frames with TRS are sent to specific receiving non-AP stations.

[0062] Upon receiving trigger frame 200, each receiving non-AP station decodes the received MSDU and its included TRS subfield to determine the allocation of resource units.

[0063] Similarly, in the case of a trigger frame, each non-AP station determines whether its AID is specified in one of the user information fields describing the allocation of resource units forming the communication channel. If yes (the AID12 subfield of the user information field is equal to 12 LSBs of the non-AP station's AID, or a reserved value notifying the random resource unit is taken), the non-AP station decodes the associated user information field.

[0064] Based on the information provided in the User Information field or the TRS Control subfield, each non-AP station knows whether it has the allocated Resource Unit. If yes, the trigger frame 200 also provides the associated transmission parameters to be used (such as MCS (modulation and coding scheme), target RSSI, etc.) and the length (duration) of the RU allocation (specified in the so-called UL Length subfield for the trigger frame, or indirectly in the UL Data Symbol subfield for the TRS Control field).

[0065] In the current scenario, STA1 and STA4 are each assigned a resource unit (RU) for MU UL transmission.

[0066] Next, these non-AP stations create MU UL data frames (HE TBPPDU) to be transmitted to the AP on the assigned RU.

[0067] To this end, the non-AP station first determines the AP-authorized transmission time (TxTime) based on the following indications provided in the trigger frame 200: the UL length subfield of the trigger frame, in which case TxTime = UL length / 3*4+24, or the UL data symbol subfield of the TRS (indicating the number of OFDM symbols in the data portion of the HE TBPPDU to be transmitted in response), in which case this information, combined with the UL HE MCS subfield of the TRS control field, provides the TxTime (because the HE TBPPDU preamble size is known). Then, the non-AP station determines the amount of data that can be transmitted within the allocated resource unit based on the MCS indicated by the AP.

[0068] Based on this information, the non-AP station creates an MSDU packet (which may contain acknowledgments or new data) and then encapsulates the MSDU packet into an HE TB PPDU. Then, the non-AP station transmits the HE TB PPDU on the allocated resource unit for the duration of the short inter-frame interval (SIFS) following the end of reception of trigger frame 200.

[0069] In the scenario shown, STA1 transmits HE TB PPDU 202 to AP, while STA4 transmits HE TB PPDU 204 to AP.

[0070] Immediately following the transmission of trigger frame 200, the AP listens to the medium, waiting to receive HE TB PPDU 202 / 204. During the transmission period of the received HE TB PPDU 202 / 204, the AP decodes all the PPDUs (required by the AP).

[0071] During the SIFS duration following the end of the transmission, the AP acquires the medium again and uses the medium to continue the cascade sequence of DL and UL transmissions until the TxOP ends.

[0072] In the scenario shown, two non-AP stations (STA2 and STA3) establish a direct link (DiL) session prior to the MU concatenation sequence. This document does not aim to describe how two peer stations establish such a direct link session. For example, stations could follow the procedures described in the 802.11 specification.

[0073] Following the HE TB PPDU 202 / 204 transmission, the AP wishes to provide DiL transmission opportunities to its peers.

[0074] To this end, the AP creates a second trigger frame 210, which instructs STA2 to act as the receiver of DiL resource elements spanning the entire operating band. This means that no other transmissions can occur in parallel with STA2's transmission. The trigger frame 210 can be an 802.11 trigger frame or a MU DL PPDU addressed to STA2 and including the TRS control subfield.

[0075] In the case of a trigger frame, a single user information field is provided, thereby assigning a unique RU (using all operating bands) to STA2. Furthermore, in trigger frame 210, the assigned RU is indicated as being dedicated to direct link transmission. Various signaling notifications can be considered to provide this indication: using 1 bit of the user information field (a reserved bit in the current version of 802.11ax); setting the AID12 field of the user information field to a specific value indicating that the RU is used for a direct link, while encoding the peer station (STA2)'s AID in a specific format in the trigger-related information field of the user information field; or using any meaningless (in the case of DiL) subfields of the user information field itself, such as bits B12 to B31, to indicate the source peer station's AID, the destination peer station's AID, or a DiL session-specific AID or identifier between the two peer stations. Any other signaling notification can be used within the context of this invention, as long as the RU is marked as being dedicated to DiL.

[0076] In the case of the TRS control field, an equivalent signal notification can be provided.

[0077] Next, the AP transmits a trigger frame 210 for providing DiL resource units to the peer stations (STA2 and STA3).

[0078] Because the AP allocates a RU for direct link transmissions (i.e., not involving the AP), the AP sets its Network Allocation Vector (NAV) to delay its next medium access until the DiL transmission ends, i.e., until the TxTime of the allocated RU ends. This is intended to avoid conflicts with DiL transmissions that the AP cannot detect (e.g., when STA3 is out of the AP's receiving range but within the range of STA2).

[0079] When trigger frame 210 is received, the peer STA2 determines that a DiL resource unit has been allocated to it based on the received frame. STA2 determines the TxTime duration based on the parameter values ​​received in trigger name 210 (e.g., UL length field from the trigger frame or UL data symbol parameters and UL HE MCS from the TRS control field).

[0080] Since the DiL duration will be shared with peer STA3, STA2 determines a new transmission time TxTime2 corresponding to the time STA2 must transmit its own DiL data. In the scenario shown (for transmissions by STA2 and STA3 respectively), this is done by subtracting two SIFS durations and the duration required for other peer STA3 to send its data or acknowledgements from the determined TxTime duration (as in the proposed scenario).

[0081] Once TxTime2 is known, STA2 determines the optimal MCS value for transmitting data based on, for example, the SNR measured during the last DiL transmission to STA3. Based on these MCS and TxTime2 values, STA2 can determine the amount of DiL data it can send to STA3. Therefore, STA2 creates a DiL PPDU 212 and transmits it on the allocated DiL RU. The DiLPPDU preferably follows a single-user frame format.

[0082] STA3 receives DiL PPDU 212 on DiL RU, decodes DiL PPDU 212, creates acknowledgment packet 214, and sends acknowledgment packet 214 to STA2 on the same DiL RU for the SIFS duration after the end of the DiL PPDU reception time.

[0083] If the amount of DiL data exchanged by the peer station is insufficient to use the allocated DiL RU during the entire TxTime, the peer station managing the allocated RU (here, STA2) can transmit padding packets 216 on the RU until the end of the RU allocation to keep it active (to prevent legacy stations from treating the channel as idle and accessing it).

[0084] During the SIFS duration following the completion of the DiL RU allocation, the AP reacquires the medium and continues the cascaded sequence of DL and UL transmissions using the medium until the end of TxOP. In the illustrated scenario, a new MU UL transmission is triggered. Trigger frame 220 and the obtained HE TB PPDUs 222 and 224 sent by the non-AP station can be managed in a similar manner to those used for trigger frame 200 and the obtained HE TB PPDUs 202 and 204.

[0085] At the end of TxOP, the AP can send a multi-STA block ACK packet 230, which acknowledges all HE TB PPDUs received during the concatenation sequence.

[0086] Although this scenario considers the cascading of two MU UL transmissions with DiL transmissions in between, other configurations can be envisioned, such as starting with a cascading of DiL transmissions, having several MU UL transmissions or several DiL transmissions on a single line, and providing MU DL transmissions between MU UL transmissions and / or DiL transmissions.

[0087] As can be readily seen from the proposed scenario, the AP may poorly assess the peer's needs and then provide too large a DiL resource unit, resulting in unnecessary padding 216 to maintain activity on the allocated resource unit until the allocated DiL time ends.

[0088] To overcome this deficiency, the present invention proposes that the peer station (here, STA2) send a resource release frame to the AP on the provided resource unit after completing the DiL transmission with STA3. In the illustrated scenario, the DiL transmission ends when STA3 completes sending acknowledgment frame 214. As a result of this transmission, the AP receives the resource release frame from the peer station on the provided resource unit. Furthermore, in response to the resource release frame, the AP can resume transmission on the resource unit, enabling the AP to reacquire the medium and continue the concatenated sequence of DL and UL transmissions using the medium until the TxOP ends. Therefore, padding is avoided, thereby saving time for other DL, UL, and / or DiL transmissions during the TxOP.

[0089] Figure 3 The same exemplary scenarios for implementing the invention according to the embodiments are illustrated.

[0090] The scenario begins as before, but is only illustrative (other types of transmissions may occur): MU UL transmission from STA1 and STA4, followed by DiL transmission of DiL PPDU 212 and acknowledgment 214.

[0091] Upon receiving acknowledgment packet 214, peer STA2 creates a resource release frame (RRF) 316, which terminates DiL transmission and enables the AP to recover its NAV via a dedicated SU PPDU.

[0092] Advantageously, the resource release frame 316 is substantially shorter than the amount of padding required to maintain activity on the communication channel. Figure 2 The result is a reduced duration of DiL resource allocation (Δtime), so bandwidth is not lost even if the AP has a long-duration NAV; and this time can be allocated to subsequent MU transmissions during TxOP (here, subsequent MU UL transmissions). Figure 3 In the example, STA1 and STA4 therefore provide a larger UL length (by Δ) for their HE TB PPDU 222, 224.

[0093] In the first embodiment, RRF 316 is an (802.11) QoS empty frame addressed to the AP. This is advantageously a very short frame, thus saving bandwidth.

[0094] In the second embodiment, RRF 316 is an enhanced (802.11) QoS empty frame that includes a buffer status report (BSR).

[0095] The transmitting peer (STA2 in this case) uses a BSR to provide its transmission requirements to the AP. This may relate to DiL transmission requirements for the current DiL session and / or all other future data transmissions (other DiL transmissions in other DiL sessions, UL transmissions, etc.). In practice, the BSR can be inserted within the so-called A control subfield (representing aggregation control) of the HE subfield of a QoS empty frame.

[0096] When the AP receives the BSR sent by STA2, the AP can schedule additional resource units for STA2 (either as a peer station or as a MUUL non-AP station).

[0097] In the third embodiment, RRF 316 is a CF-End frame as described in the IEEE 802.11-2016 specification (Section 9.3.1.7), but addressed to the AP (CF-End is used as a unicast frame). This contrasts sharply with the specification that broadcasts CF-End frames to notify all stations (AP and non-AP) of the end of the TxOP. By addressing the CF-End only to the AP, the third embodiment ensures that only the AP is aware that the DiL resource has been released. This allows the AP to regain control of the communication channel first by restoring its NAV (because its authorized TxOP is still ongoing).

[0098] The scenario shown in the diagram is for illustrative purposes only. Numerous scenarios can be envisioned where resource units are allocated for DiL during a sub-part of the TxOP authorized to the AP.

[0099] Figure 3a Examples Figure 3 A slight variation, in which the peer station also sends a resource acknowledgment frame 311 to the AP in response to receiving trigger frame 210, before initiating DiL transmission with another peer station. Therefore, the AP receives this message and can set its NAV accordingly.

[0100] The Resource Acknowledgment Frame (RAF 311) is formatted as an HE TB PPDU. Its multiple roles include announcing the start of a DiL transmission, acknowledging receipt of a TF sent by the AP, and enabling the AP to set its NAV.

[0101] The payload of RAF 311 can be any payload formatted as an HE TB PPDU as described in RRF 316 (QoS empty frame, QoS empty frame + BSR, CF-END frame). In the 802.11ax standard draft version 6.0 (D6.0) of November 2019, the AP verifies good reception of the trigger frame by receiving the HE TB PPDU. Therefore, RAF 311 advantageously ensures compliance with the 802.11ax standard.

[0102] Figure 4 The general steps at the AP for implementing the present invention are illustrated using a flowchart. Only the AP operation during the DiL phase provided within the authorized TxOP is described (operations managing UL and DL transmissions are not shown).

[0103] In step 400, the AP determines the duration (UL length or UL data symbol with associated MCS) of the next cascading phase (here, the DiL phase). This can be based on the DiL requirements declared to the AP by the peer stations (STA2, STA3). The AP then generates a trigger frame 210 (trigger frame or MU PPDU with TRS) to allocate at least one RU for DiL transmission within the determined duration.

[0104] The DiL RU can encompass the entire operating frequency band. Alternatively, the DiL RU can be a multiple of 20 MHz (aligned over an 802.11 channel) but thinner than the operating frequency band. In this case, preferably, the DiL RU's frequency band includes the main channel, allowing conventional peer stations to easily detect packets.

[0105] In some embodiments, trigger frame 210 includes an additional indication to allocate one or more other DiL resource units to the same peer station during the current TxOP (i.e., in a subsequent phase of the cascading sequence).

[0106] In step 410, the AP transmits the generated trigger frame 210 on the current operating frequency band.

[0107] In step 420, the AP sets its NAV settings for the duration determined in step 400. This step is optional. Additionally, step 420 may be in response to receiving a resource acknowledgment frame RAF311 (test 415) from a peer station.

[0108] Steps 430 and 440 track the end of DiL RU allocation due to NAV expiration or RRF 216 reception. Although the figure shows one order of the two tests, the reverse order is also possible.

[0109] When one of the two tests is positive (meaning that the AP regains access to the medium), the next stage of the cascade sequence (step 450) is initiated for new data transfer within the authorized TxOP.

[0110] Figure 5a and 5b A flowchart illustrates the general steps at the peer station in a DiL transfer.

[0111] Figure 5a An example is given of the peer station of the DiL RU responsible for AP allocation (e.g., Figure 3 The operation at STA2 (when it sends DiL data).

[0112] In step 510, the peer station receives, for example, a trigger frame 210 containing a trigger frame or a QoS data MSDU with a TRS control field.

[0113] In step 520, the peer station decodes the contents of the received trigger frame to determine whether the AP has allocated a DiL RU to the peer station, and if so, which RU. The peer station also retrieves the associated transmission parameters and the DiL allocation duration.

[0114] Optional step 525 includes sending a resource acknowledgment frame (RAF) 311 to the AP.

[0115] In step 530, the peer station determines the duration TxTime2 of the DiL PPDU transmission. As previously mentioned, this duration can be calculated using the UL length value, the selected MCS, and the DiL requirements of other peer stations.

[0116] In step 540, using TxTime2, the peer station prepares PPDU 212 (including the acknowledgment policy for the transmission) for direct link transmission and transmits it on the assigned DiL RU.

[0117] Optional step 550: Wait for and decode the immediate acknowledgment 214 sent by the destination peer (STA3 in this case) transmitted by DiL.

[0118] In step 560, the DiL transmission ends. The peer sends an RRF 316 to the AP as a dedicated SU PPDU. This causes the AP to restore its NAV (if configured) and recover the media access that was offloaded to the peer.

[0119] Figure 5b Examples are given for other peer sites (e.g.) Figure 3 The operation at STA3 in the middle.

[0120] In step 580, the peer station receives DiL PPDU 212 from the initiating peer station (STA2) in SU PPDU format on multiples of the 20MHz band (possibly all operating bands).

[0121] In some embodiments, the peer station may be prepared to receive the DiL PPDU 212 by pre-decoding the trigger frame 210. In a variant, the peer station senses the medium only in the operating band and detects the DiL PPDU 212 addressed to the peer station (upon arrival).

[0122] Optional step 590 determines whether immediate acknowledgment is required. If yes, PPDU 214 containing acknowledgment of successful reception is prepared and sent back to the initiating peer on the same DiL RU (SIFS after the reception of DiL PPDU 212).

[0123] Figure 6a A communication device 600 (non-AP device station 101-107 or access point 110) configured to implement at least one embodiment of the present invention is illustrated schematically. The communication device 600 may preferably be a device such as a microcomputer, workstation, or lightweight portable device. The communication device 600 includes a communication bus 613, which is preferably connected to:

[0124] Central processing unit 601, such as processor, is referred to as CPU;

[0125] Memory 603 is used to store executable code of the method or method steps according to embodiments of the present invention, and registers adapted to record variables and parameters required to implement the method; and

[0126] At least one communication interface 602 is connected to a wireless communication network (e.g., a communication network according to one of the IEEE 802.11 standard families) via a transmit antenna and a receive antenna 604.

[0127] Preferably, the communication bus provides communication and interoperability between various elements included in or connected to the communication device 600. The representation of the bus is not limited, and specifically, the central processing unit is operable to communicate instructions directly or by means of another element of the communication device 600 to any element of the communication device 600.

[0128] The executable code can be stored in memory, which can be read-only, a hard disk, or a removable digital medium such as a disk. Alternatively, the executable code of the program can be received via interface 602 through a communication network and stored in the memory of the communication device 600 before being executed.

[0129] In the embodiments, the apparatus is a programmable device that uses software to implement embodiments of the invention. However, alternatively, embodiments of the invention may be implemented wholly or partially in hardware (e.g., in the form of an application-specific integrated circuit or ASIC).

[0130] Figure 6b This is a block diagram schematically illustrating the architecture of a communication device 600 (one of stations 101-107 or AP 110) suitable for at least partially implementing the present invention. As shown, device 600 includes a physical (PHY) layer block 623, a MAC layer block 622, and an application layer block 621.

[0131] PHY layer block 623 (here, the 802.11 standardized PHY layer) has the following tasks: formatting, modulation or demodulation on any 20MHz channel or composite channel, and therefore transmitting or receiving frames on a radio medium using 100 (such as 802.11 frames, e.g., media access trigger frame TF210 for interacting with conventional 802.11 stations based on a 20MHz width reserved transmission slot, MAC data and management frames, and OFDMA type MAC data frames (with a width less than the conventional 20MHz relative to the radio medium (typically 2 or 5MHz)).

[0132] The MAC layer block or controller 622 preferably includes a MAC 802.11 layer 624 that implements conventional 802.11ax MAC operations and an additional block 625 for at least partially performing the present invention. The MAC layer block 622 may optionally be implemented in software, which is loaded into RAM 603 and executed by CPU 601.

[0133] Preferably, an additional block 625, referred to as the trigger direct link Tx management module, implements a portion of an embodiment of the invention (from the slave station's perspective or from the AP's perspective). This block is configured according to the role of the communication device 600. Figure 4 , Figure 5a and / or Figure 5b The operation.

[0134] The MAC 802.11 layer 624 and the trigger direct link Tx management module 625 interact with each other to properly handle communications addressed to multiple stations on the OFDMA RU according to an embodiment of the invention.

[0135] At the top of the diagram, application layer block 621 runs applications that generate and receive data packets (such as video streams). Application layer block 621 represents all stack layers above the MAC layer, as standardized by ISO.

[0136] Although the present invention has been described above with reference to specific embodiments, the present invention is not limited to the specific embodiments, and modifications within the scope of the present invention will be apparent to those skilled in the art.

[0137] Many further modifications and variations will be made to those skilled in the art upon reference to the foregoing illustrative embodiments, which are given by way of example only and are not intended to limit the scope of the invention, which is defined only by the appended claims. In particular, different features from different embodiments may be interchanged where appropriate.

[0138] In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude multiple. The fact that different features are listed merely in mutually different dependent claims does not imply that combinations of these features cannot be used advantageously.

Claims

1. A communication method in a wireless network, comprising: At the station, The station receives a trigger frame from the access point (AP), which provides the station with resources for direct transmission during the transmission opportunity (TxOP) granted to the AP through Enhanced Distributed Channel Access Contention (EDCA) contention. Data transmission is performed using the provided resources, and Upon completion of the data transmission, a frame is sent to the AP using the provided resources to enable the release of the provided resources, so that the AP can transmit on the resources during the TxOP without EDCA contention.

2. The method according to claim 1, wherein, The provided resources are frequency resources with a bandwidth that is a multiple of 20 MHz, and the data transmission is performed by using the frequency resources.

3. The method according to claim 1 or 2, wherein, Provide a predefined duration for the resource, and send a frame to enable the release of the provided resource before the end of the predefined duration.

4. The method according to claim 1 or 2, further comprising: At the station, in response to receiving the trigger frame, a resource acknowledgment frame is sent to the AP to confirm the provided resources before the data transmission begins.

5. The method according to claim 1 or 2, further comprising: During the authorized TxOP, one or more trigger frames are received from the AP to trigger multi-user transmissions (MU transmissions).

6. The method according to claim 1 or 2, wherein, The frame used to release the provided resources is a single-user data frame, i.e., a SU data frame.

7. The method according to claim 1 or 2, wherein, The frame used to release the provided resources is an 802.11 QoS empty frame.

8. The method according to claim 1 or 2, wherein, The frame used to release the provided resources is an enhanced 802.11 QoS empty frame that includes a buffer status report, or BSR.

9. The method according to claim 8, wherein, The BSR includes direct transmission requirements between the station and another station.

10. The method according to claim 1 or 2, wherein, The frame used to release the provided resources is a unicast 802.11 CF-End frame addressed to the AP.

11. A communication method in a wireless network, comprising: At the access point (AP), during the transmission opportunity (TxOP) granted to the AP through Enhanced Distributed Channel Access Contention (EDCA) contention... The station transmits a trigger frame that provides resources that can be used for direct transmission. By using the provided resources, a frame for releasing the provided resources is received from one of the stations, and In response to the frame used for release, other data transmissions are performed on the resource during the TxOP without EDCA contention.

12. The method according to claim 11, wherein, The provided resources are frequency resources with bandwidth that is a multiple of 20 MHz, and the data transmission is performed by using the frequency resources.

13. The method according to claim 11 or 12, wherein, Provide a predefined duration for the resource, and receive a frame for releasing the provided resource before the predefined duration ends.

14. The method of claim 13, further comprising: Configure a network allocation vector (NAV) to delay the media access of the AP until the end of the predefined duration.

15. The method of claim 14, further comprising: As the AP, after transmitting the trigger frame, it receives a resource confirmation frame from one of the stations to confirm the provided resources, wherein setting the NAV is performed in response to receiving the resource confirmation frame.

16. The method according to claim 11 or 12, further comprising: During the authorized TxOP, one or more trigger frames are transmitted to trigger multi-user transmissions, i.e., MU transmissions.

17. The method according to claim 11 or 12, wherein, The frame used to release the provided resources is a single-user data frame, i.e., a SU data frame.

18. The method according to claim 11 or 12, wherein, The frame used to release the provided resources is an 802.11 QoS empty frame.

19. The method according to claim 11 or 12, wherein, The frame used to release the provided resources is an enhanced 802.11 QoS empty frame that includes a buffer status report, or BSR.

20. The method according to claim 19, wherein, The BSR includes direct transmission requirements between the station and another station.

21. The method according to claim 11 or 12, wherein, The frame used to release the provided resources is a unicast 802.11 CF-End frame addressed to the AP.

22. A wireless communication device comprising at least one microprocessor configured to perform the steps of the method according to any one of claims 1 to 21.

23. A non-transitory computer-readable medium storing a program that, when executed by a microprocessor or computer system in a wireless device, causes the wireless device to perform the method according to any one of claims 1 to 21.

24. A computer program product comprising a program that, when executed by a microprocessor or computer system in a wireless device, causes the wireless device to perform the method according to any one of claims 1 to 21.

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