CN118054881A - Link protection in enhanced long range ELR communications using RTS/CTS - Google Patents

Abstract

In one aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The device may be a wireless communication station STA. In some configurations, the STA sends a request to send RTS frame in an enhanced long range ELR format to acquire a transmission opportunity TXOP. The STA receives a first clear to send CTS frame in response to the RTS frame, the first CTS frame being in ELR format or non-ELR format. In response to receiving the first CTS frame, the STA transmits data in ELR format within the TXOP. In some configurations, the STA further receives an acknowledgement in the same format as the first CTS frame in response to the transmitted data. In some configurations, the STA transmits a CTS-to-Self frame in a non-ELR format before transmitting the RTS frame.

Description

Link protection in enhanced long range ELR communications using RTS/CTS

Cross-reference to related applications

The present application claims the benefits of U.S. provisional application serial No. 63/384,109 filed on 11 months 17 of 2022, and the benefits of U.S. non-provisional application serial No. 18/509,559 filed on 11 months 15 of 2023, entitled "link protection in enhanced long distance (ELR) communications using RTS/CTS," which is incorporated herein by reference in its entirety.

Technical Field

The present disclosure relates to communication systems, and more particularly to techniques for methods and apparatus for link protection in Enhanced Long Range (ELR) transmissions using Request To Send (RTS)/Clear To Send (CTS).

Background

Wi-Fi achieves a successful ecosystem worldwide, with over 200 billion devices currently connected to support high-speed and efficient wireless services, as well as highly reliable and cost-effective internet of things (IoT) devices. A large number of deployed IoT devices using 802.11b may provide maximum coverage but may suffer from limited spectral efficiency and forward compatibility issues. The link distance may be extended by 3dB using a High Efficiency (HE) Extended Range (ER) Single User (SU) physical layer protocol data unit (PPDU). However, the benefits of using HE ER SU PPDUs are generally limited by the uplink, and still do not meet market demands, since the imbalance in transmission power between the transmission point (AP) and the non-AP Stations (STAs) reaches 6 dB.

Disclosure of Invention

The following presents a simplified summary of one or more aspects of the disclosure in order to provide a basic understanding of such aspects. There is no broad overview of all contemplated aspects, nor does it identify or set forth key or critical elements of all aspects, nor delineate the scope of any or all aspects. Its sole purpose is to present some concepts of the certain concepts in a simplified form as a prelude to the more detailed description that is presented later.

In one aspect of the disclosure, a method, computer-readable medium, and apparatus are provided. The device may be a Station (STA). In some configurations, the STA transmits a Request-to-Send (RTS) frame in an enhanced long range (Enhanced Long Range, ELR) format to obtain a transmission opportunity (Transmission Opportunity, TXOP). The STA receives a first Clear-to-Send (CTS) frame in ELR format or non-ELR format in response to the RTS frame. In response to receiving the first CTS frame, the STA transmits data in ELR format within the TXOP.

In some configurations, the STA further receives an acknowledgement in the same format as the first CTS frame in response to the data being transmitted.

In some configurations, the STA transmits a CTS-to-Self frame in a non-ELR format before transmitting the RTS frame.

In some configurations, the STA waits for a period of time in response to receiving the first CTS frame. The STA receives the second CTS frame in this period. One of the first CTS frame and the second CTS frame is in ELR format, and the other of the first CTS frame and the second CTS frame is in non-ELR format. The data is sent after the period of time.

In some configurations, the STA transmits a single CF-end frame or a double CF-end frame to terminate the TXOP in response to not receiving any CTS frame or fully transmitting data in ELR format within an estimated transmission period.

In another aspect of the disclosure, a method, computer-readable medium, and apparatus (device) are provided. The device may be a STA. In some configurations, the STA receives an RTS frame in ELR format or non-ELR format. The STA sends a single CTS frame or a double CTS frame on the channel in response to the RTS frame. The dual CTS frames include a primary CTS frame in ELR format and a secondary CTS frame in non-ELR format. The STA receives data on the channel. In response to receiving the data, the STA transmits an acknowledgement of the response data on the channel. The acknowledgement is in the same format as the first CTS frame of either a single CTS frame or a double CTS frame in response to the RTS frame.

To the accomplishment of the foregoing and related ends, one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth certain illustrative features of the one or more aspects. These features are indicative, however, of a few of the examples of the various ways in which the principles of the disclosure may be employed.

Drawings

FIG. 1 illustrates an example network environment.

Fig. 2 shows an example design of an ELR PPDU structure.

Fig. 3 shows an example in the existing Wi-Fi standard using MU-RTS and CTS-triggered OFDMA, and an example of CTS-separation for new control frame delivery.

Fig. 4 illustrates an example procedure for ELR-RTS/CTS transmission by a STA.

Fig. 5 shows an example procedure of data transmission of two STAs in fig. 4.

Fig. 6 shows an example procedure for RTS/CTS transmission by two STAs in fig. 4.

Fig. 7 illustrates an example procedure for ELR-RTS/CTS transmission of an STA, where link protection allows OBSS legacy STAs to set NAV.

Fig. 8 shows an example procedure of RTS/CTS transmission of two STAs in fig. 7.

Fig. 9 shows an example procedure for ELR-RTS/CTS transmission for STAs with full link protection.

Fig. 10 shows an example procedure of RTS/CTS transmission of two STAs in fig. 9.

Fig. 11 illustrates an example procedure for ELR-RTS/CTS transmission by an ELR STA with link protection.

Fig. 12 shows an example procedure of RTS/CTS transmission of the AP and ELR STA in fig. 11.

Fig. 13 shows an example procedure for RTS/CTS transmission by an ELR STA with link protection, with legacy APs.

Fig. 14 shows an example procedure of RTS/CTS transmission of the AP and ELR STA in fig. 13.

Fig. 15 illustrates an example communication system.

Fig. 16 is a flowchart of a wireless communication method (procedure) of the STA.

Fig. 17 is a flowchart of a wireless communication method (procedure) of the STA.

Detailed Description

The following detailed description, given with reference to the accompanying drawings, is intended as a description of various configurations and is not intended to represent the only configuration in which the concepts described herein may be practiced. The detailed description includes specific details necessary to provide a thorough understanding of the various concepts. However, it will be understood by those skilled in the art that the concepts may be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form in order to avoid obscuring the concepts.

Several aspects of the telecommunications system will be presented with reference to various devices and methods. These devices and methods will be described in the following detailed description and accompanying drawings by various modules, components, circuits, processes, algorithms, etc. (collectively referred to as "elements"). These elements may be implemented using electronic hardware, computer software, or any combination of the two. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

For example, any portion of an element or any combination of elements can be implemented as a "processing system" that includes one or more processors. Examples of processors include microprocessors, microcontrollers, graphics Processing Units (GPUs), central Processing Units (CPUs), application processors, digital Signal Processors (DSPs), reduced Instruction Set Computing (RISC) processors, system on a chip (SoC), baseband processors, field Programmable Gate Arrays (FPGAs), programmable Logic Devices (PLDs), state machines, gating logic, discrete hardware circuits, and other suitable hardware configured to perform the various functions described in this disclosure. One or more processors in the processing system may execute the software. Software should be construed broadly as instructions, instruction sets, code segments, program code, programs, subroutines, software components, applications, software packages, routines, subroutines, objects, executable files, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

For example, in one or more example aspects, the functionality may be implemented as hardware, software, or any combination of the two. If implemented in software, the functions may be stored on or encoded as one or more instructions or code on a computer-readable medium. Computer readable media includes computer storage media. A storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise Random Access Memory (RAM), read-only memory (ROM), electrically Erasable Programmable ROM (EEPROM), optical disk storage, magnetic disk storage, other magnetic storage devices, combinations of the above, or any other medium that can store instructions or data structures in the form of computer-executable code that can be accessed by a computer.

As previously described, the link distance may be extended by 3dB using the HE ER SU PPDU. However, the advantages of using HE ER SU PPDUs are generally limited by the uplink, and still do not meet the market demand, since the imbalance in transmission power between AP and non-AP STAs reaches 6 dB. In this case, an enhanced long distance (ELR) communication scheme is proposed, and the range of the downlink and uplink can be further extended.

Fig. 1 illustrates an example network environment 100. The network environment 100 may involve wireless communications between a transmission Point (AP) 110 and a plurality of Non-AP stations (Non-AP stations) in accordance with the IEEE 802.11 standard. The AP 110 has Non-High Throughput (Non-HT) coverage 112 and enhanced long distance (Enhanced Long Range ELR) coverage 114. The non-AP STAs include an enhanced communication (ENHANCED REACH, abbreviated ER) STA 120, which is a non-AP STA supporting ER but not ELR, and an ELR STA 130, which is a non-AP STA supporting ELR. ER STA 120 corresponds to having non-HT coverage 122 and ER coverage 124, and ELR STA 130 corresponds to having non-HT coverage 132 and ELR coverage 134. As shown in fig. 1, ER STA 120 is located within non-HT coverage 112 of AP 110, ELR STA 130 is located within ELR coverage 114 of AP 120 but outside non-HT coverage 112 of AP 110. The AP 110 is located within the ELR coverage 134 of the ELR STA 130 but outside the ER coverage 124 of the ER STA 120. In some configurations, the network environment 100 may include one or more other non-AP STAs, each of which may be an ER STA (i.e., an ER-capable non-AP STA), an ELR STA (i.e., an ELR-capable non-AP STA), or a non-AP STA that supports both ELR and ER.

Specifically, the ER PPDU for the ER STA 120 is only beneficial for uplink transmission because the imbalance in transmission power between the AP and the non-AP STAs reaches 6 dB. Further, it should be noted that since the AP 110 is located outside the ER coverage 124 of the ER STA 120, as shown in fig. 1, a non-AP using an ER PPDU (i.e., the ER STA 120) may still not be connected to the AP 110. Further, as shown in fig. 1, ELR STA 130, which is located outside of non-HT coverage 112 of AP 110, cannot receive downlink and uplink communications of legacy preambles (i.e., L-STF/LTF/SIG). Thus, in the proposed Enhanced Long Range (ELR) communication scheme, a new ELR waveform is proposed, greatly improving the link distance.

Fig. 2 shows an example design of an ELR PPDU structure 200. In general, the legacy preamble of the PPDU includes a Short training field (Short TRAINING FIELD, abbreviated STF), a Long training field (Long TRAINING FIELD, abbreviated LTF), and a Signal (SIG) field, and the ELR PPDU structure 200 employs the legacy preamble, e.g., L-STF, L-LTF, and L-SIG fields, and repeated legacy SIG (REPEATED LEGACY SIG, abbreviated RL-SIG) fields, to fool IEEE802.11 a/g/n/ac/ax/be-based devices. In addition, the ELR PPDU structure 200 employs one or more common SIG (U-SIG) fields after the legacy preamble field for forward compatibility purposes and to provide ELR PPDU information in the upcoming Wi-Fi standard. ELR PPDU information that may be provided in the U-SIG field includes, but is not limited to, physical layer (PHYSICAL LAYER, PHY) version, PPDU type, bandwidth, transmission direction, basic SERVICE SET (BSS), color of Basic Service Set (BSS), and transmission opportunity (Transmission Opportunity, TXOP). Accordingly, in the ELR PPDU structure 200, backward compatibility is achieved through legacy preamble fields (i.e., L-STF/LTF/SIG field and RL-SIG field) for spoofing, and forward compatibility is achieved through the U-SIG field. The power boosting may be used for spoofing as well as for the U-SIG portion to provide an enhanced spoofing range. In addition, after the U-SIG field, the ELR PPDU structure 200 may employ an ELR-STF/LTF/SIG/Data field newly designed for an ELR application, providing a significant improvement in transmission distance as compared to conventional devices based on IEEE802.11 a/b/g/n/ac/ax/be.

In some configurations, it is expected that ELR PPDU structure 200 will support orthogonal frequency division multiple access (Orthogonal Frequency Division Multiple Access, abbreviated OFDMA), which is a multi-user version of the orthogonal frequency division multiplexing (Orthogonal Frequency Division Multiplexing, abbreviated OFDM) digital modulation scheme. Furthermore, in the ELR PPDU structure 200, the ELR-STF/LTF field may achieve a reasonably low peak-to-average ratio (Peak to Average Power Ratio, abbreviated PAPR) to achieve higher power enhancement than IEEE 802.11a/b/g/n/ac/ax/be based devices. The ELR-SIG/Data field may utilize the receive sensitivity and Data rate to provide significant coverage enhancement. The ELR-STF/LTF/SIG/Data field may support a bandwidth of 20MHz or less.

In addition, link protection for ELR downlink and uplink communications and coexistence with STAs without ELR capabilities (e.g., STAs that do not support ELR PPDUs) are important on the basis of transmission power imbalance between the ELR PPDU structure 200 and the AP 110 and non-AP STAs (e.g., ER STA 120 and ELR STA 130). Specifically, link protection using Request To Send (RTS) and Clear To Send (CTS) frames is optional in IEEE 802.11 because RTS and CTS frames are transmitted in a legacy format (802.11 a) with the lowest 6Mbps data rate, which is less spectrally efficient than conventional traffic. But the advantages of RTS/CTS need to be exploited. First, in Wi-Fi networks with high load and range expansion, high collisions may result in data retransmissions and consume valuable communication time/frequency resources. In this case, it is desirable to use RTS and CTS to reduce collisions and improve resource unit utilization. However, conventional RTS and CTS do not support ELR users well, and thus enhanced RTS and CTS mechanisms are needed. Second, OFMDA can improve the utilization of resource units. Therefore, in newly designed Multi-User (MU) RTS and CTS mechanisms, it is desirable to support both OFDMA and ELR.

Since RTS/CTS and ELR may be optional functions in the upcoming standard, one aspect of the present disclosure relates to mechanisms to achieve link protection using RTS/CTS over ELR PPDUs to meet ELR transmissions under different considerations.

To achieve similar behavior for multiple clients, MU-RTS and CTS are employed in the current Wi-Fi standard. Fig. 3 shows an example of using MU-RTS and CTS to trigger OFDMA in the existing Wi-Fi standard, and CTS separation for new control frame transfer. As shown in part (a) of fig. 3, when the AP 110 transmits a legacy MU-RTS frame (i.e., MU-RTS transmitted over a legacy PPDU structure instead of ELR PPDU structure 300) to a plurality of STAs (possibly non-AP STAs, e.g., ER STA 120 and ELR STA 130) over a channel, the legacy MU-RTS frame may trigger one or more STAs (including STA1 through STA 4) to transmit back a legacy CTS frame (i.e., CTS transmitted over the legacy PPDU structure instead of ELR PPDU structure 300). However, multiple STAs (i.e., STA1 through STA 4) may simultaneously transmit a legacy CTS frame (of the same format and duration) back to the AP 110, such that the AP 110 may not be able to distinguish the respective sources of the legacy CTS frame received from the STAs. For example, as shown in part (b) of fig. 3, if one of the STAs (e.g., STA 4) is busy in a clear channel assessment (CLEAR CHANNEL ASSESSMENT, CCA for short) mechanism, STA4 will not transmit a legacy CTS frame back to the AP 110, and the AP 110 will only receive three legacy CTS frames from the other three STAs (i.e., STA1, STA2, and STA 3). However, the AP 110 may not be able to identify the respective source STAs (i.e., STA1, STA2, and STA 3) of the received legacy CTS frame. Thus, the AP 110 may still attempt to transmit data to the busy STA4, and the data transmitted to the STA4 will fail at the receiving end. This problem is not solved under the conventional PPDU format due to limitations in backward compatibility and communication time utilization efficiency.

In contrast, to transmit ELR STAs (e.g., ELR STA 130) that are not outside the non-HT coverage 112 of the AP 110, a new design of ELR PPDU structure 300 may be utilized. However, the ELR PPDU structure 300 cannot be understood by legacy devices (e.g., ER STAs 120). Therefore, a new control frame transmission scheme needs to be designed. In particular, CTS separation may be supported to let the AP 110 know the true channel conditions, where CTS for non-overlapping Resource Units (RUs) of the ELR or orthogonally encoded CTS may be potential candidates. As shown in part (c) of fig. 3, when the AP 110 transmits an ELR MU-RTS frame (i.e., MU-RTS transmitted over the ELR PPDU structure 300) to a plurality of STAs, the ELR MU-RTS frame may trigger one or more STAs (including STA1 through STA 4) to transmit an ELR-CTS (i.e., CTS transmitted over the ELR PPDU structure 300) back. Accordingly, the responding STAs (including STA1, STA2, and STA 3) may transmit respective ELR-CTS frames back to the AP 110 in corresponding non-overlapping RUs so that the AP 110 may identify the respective source STAs of the ELR-CTS frames. On the other hand, for STA4 whose CCA is busy, the AP 110 may determine to re-reserve the TXOP or continuously transmit data using the non-busy RU, as shown in part (c) of fig. 3. It should be noted that if the supported BSS bandwidth is greater than 20MHz, the CTS separation may cover non-primary channel access, as compared to a conventional CTS frame that is always sent on the primary channel, so that ELR-CTS frames may be transmitted on both the primary and non-primary channels.

Fig. 4 shows an example procedure for ELR-RTS/CTS transmission by a STA. STA 402 may be an AP. In the example process 400, the STA 402 (i.e., the AP 110) is located in a position where a legacy STA 404 (which may be a non-AP STA that does not support ELR, such as the ER STA 120) and two ELR STAs 405 and 406 (which may be non-AP STAs that support ELR, such as the ELR STA 130) are located within ELR coverage of the STA 402. The distance of each ELR STA 405 and 406, respectively, from STA 402 is such that an ELR PPDU is required to transmit the RTS/CTS frame. In addition, the ELR STA 406 is located within range of an Overlapping BSS (OBSS) legacy STA 408 (a non-AP STA that may belong to another BSS that does not support ELR). OBSS legacy STAs 408 may be located within STA ELR coverage of STA 402 or outside STA ELR coverage of STA 402. In some configurations, STA 402 and ELR STAs 405 and 406 support ELR and OFDMA.

STA 402 may have data to transmit to one or more ELR STAs 405 and 406, which is expected to transmit through ELR PPDU structure 300. If the ELR PPDU structure 300 is expected to carry only a single Medium Access Control (MAC) protocol data unit (MPDU), or the total communication time requirement is small, the STA 402 may directly transmit the ELR data without performing the ELR-RTS/CTS procedure.

Fig. 5 shows an example process of data transmission for two STAs in fig. 4. Specifically, the STA 502 may be the STA 402, e.g., an AP, and the STA 504 may be the ELR STA 406, e.g., a non-AP STA. As previously discussed, if the STA 502 (i.e., the STA 402) intends to transmit an ELR PPDU structure carrying a single MPDU, or the total communication time requirement is small, the STA 502 may generate and transmit the ELR PPDU 550 to the STA 504 without performing an ELR-RTS/CTS procedure. At the STA 504, after receiving the ELR PPDU 550 and waiting for the SIFS duration, the STA 504 transmits an ELR ACK 560 back to the STA 502. In some implementations, the SIFS duration may be 16 μs.

Referring to fig. 4, on the other hand, if the ELR PPDU structure 300 is expected to carry an Aggregate MPDU (AMPDU) or there are multiple ELR PPDU structures to transmit and the total communication time requirement is relatively large, the STA 402 may attempt to reserve a transmission opportunity (TXOP) so that the protected TXOP may reduce the chances of collision and retransmission, thereby facilitating ELR communication. Specifically, if ELR STAs 405 and 406 are located outside the non-HT coverage of STA 402, STA 402 may utilize the ELR-RTS/CTS mechanism to reserve a TXOP. In other words, STA 402 may attempt to become a TXOP holder in a network environment.

As shown in fig. 4, at operation 410, the STA 402 generates an ELR-RTS frame 420 (e.g., MU-RTS transmitted over the ELR PPDU structure 300) to reserve the TXOP of the STA 402 and broadcasts the ELR RTS frame 420 on a channel such that legacy STAs 404 and ELR STAs 405 and 406 within the AP ELR coverage receive the broadcasted ELR RTS frame 420. Upon broadcasting ELR RTS frame 420, STA 402 expects to receive a corresponding ELR CTS frame from one or more ELR STAs 405 and 406. Specifically, STA 402 may set a TXOP duration RTS threshold, which may be adjusted according to network conditions. In some configurations, although the transmissions in the example process 400 are downlink transmissions as an example, the procedure of ELR-RTS/CTS transmission may be set for downlink and uplink transmissions.

Once STA 402 broadcasts ELR RTS frame 420, ELR STAs 405 and 406 may receive ELR RTS frame 420 and perform the corresponding operations. Specifically, at operation 440, in response to the ELR RTS frame 420, the ELR STA 406 generates a corresponding ELR CTS frame 450 and transmits the ELR CTS frame 450 to the STA 402 and OBSS legacy STA 408 over the channel. Specifically, to initialize OFDMA using MU-RTS frames (i.e., ELR RTS frames 420) in ELR communications, ELR CTS frames 450 may support orthogonal transmissions, e.g., in an RU or encoded domain, allowing STAs 402 to separate sources of ELR CTS frames 450.

Meanwhile, at operation 430, in response to ELR RTS frame 420, ELR STA 405 sets a network allocation vector (network allocation vector, abbreviated NAV), which is a virtual carrier sense mechanism that is used to represent the duration that specifies the estimated transmission time required by STA 402. Specifically, upon receiving ELR RTS frame 420, ELR STA 405 identifies that the channel will be occupied for a duration (i.e., estimated transmission time) and ELR STA 405 should refrain from transmitting data on the channel for this duration. In one embodiment, the NAV may represent the duration in the form of a counter. When the counter value of the NAV is non-zero, the ELR STA 405 determines that the channel is busy, so the ELR STA 405 may choose not to transmit any data on the channel to avoid potential collisions. When the NAV count decreases to zero, the ELR STA 405 determines that the channel becomes idle, and thus the ELR STA 405 may freely transmit data on the channel. In some configurations, the STA 402 and ELR STAs 405 and 406 (or any other ELR-enabled non-AP STAs) may support new NAV counters and reset schemes. However, the legacy STA 404 does not understand the ELR RTS frame 420 (or any messages in the ELR PPDU structure 300 or messages in ELR format). Thus, when the legacy STA 404 receives the ELR RTS frame 420, the legacy STA 404 will not set the NAV, which may cause the STA 402 to further collide when receiving on the channel.

After the ELR STA 406 transmits the ELR CTS frame 450, the STA 402 may process the data to be transmitted and generate ELR data (i.e., data in the at least one ELR PPDU structure 300) in response to receiving the ELR CTS frame 450 at operation 460. However, the OBSS legacy STA 408 does not understand the ELR CTS frame (or any message in the ELR PPDU structure 300 or any message in ELR format). Accordingly, when the OBSS legacy STA 408 receives the ELR CTS frame 450, the OBSS legacy STA 408 may not set the NAV, which may cause further reception collisions by the ELR STA 406 on the channel.

At operation 470, the STA 402 transmits ELR data to the ELR STA 406 on the channel. However, the OBSS legacy STAs 408 may also transmit data on the channel in their own BSS at the same time, and at operation 475, the data may be received by the ELR STA 406 and thus collide with the ELR data 470. If the ELR STA 406 successfully receives the ELR data 470, the ELR STA 406 transmits a corresponding ELR acknowledgement (ELR-ACK) to the STA 402 on the channel at operation 480. However, at operation 490, the legacy STA 404 may also transmit data to the STA 402 on the channel at the same time and thus collide with the ELR-ACK 480.

Fig. 6 shows an example procedure of RTS/CTS transmission by two STAs in fig. 4. Specifically, the STA 602 may be the STA 402, e.g., an AP, and the STA 604 may be the ELR STA 406, e.g., a non-AP STA. As shown in fig. 6, STA 602 (i.e., STA 402) generates and broadcasts ELR RTS frame 620 (i.e., ELR RTS frame 420). At the STA 604 (i.e., ELR STA 406), after receiving the broadcasted ELR RTS frame 620 and waiting for the SIFS duration, the STA 604 transmits an ELR CTS frame 630 (i.e., ELR CTS frame 450). At the STA 602, after receiving the ELR CTS 630 and waiting for another SIFS duration, the STA 602 transmits an ELR PPDU 650 (i.e., ELR data 470). Then, at the STA 604, after receiving the ELR PPDU 650 and waiting for another SIFS duration, the STA 604 transmits an ELR ACK 660 (i.e., ELR ACK 480). In some embodiments, each SIFS duration may be 16 μs. In some configurations, in the ELR BSS, the ELR-NAV timeout period is (2×asifstime) + (ELR-cts_time) + aRxPHYStartDelay + (2×asilottime), where aRxPHYStartDelay is one or more integer delay values for each supported PHY clause, where each delay (in microseconds) is from the start of the PPDU at the receiver antenna to the issuance (if transmitted) of the PHY-rxearlyig. Indication primitive or PHY-rxstart. Indication primitive. In contrast, the legacy NAV timeout period may be (2×aSIFSTime) + (LG-CTS_Time) + aRxPHYStartDelay + (2×aSlotTime).

Fig. 7 illustrates an example procedure for ELR-RTS/CTS transmission for STAs that achieve link protection by allowing OBSS legacy STAs to set NAVs. STA 702 may be an AP. Similar to example process 400, in example process 700, STA 702 (i.e., AP 110) is located where legacy STA 704 (which may be a non-AP STA that does not support ELR, such as ER STA 120) and two ELR STAs 705 and 706 (which may be non-AP STAs that support ELR, such as ELR STA 130) are within ELR coverage of STA 702. The distance of each ELR STA 705 and 706, respectively, from STA 702 requires an ELR PPDU to carry the RTS/CTS frame. In addition, the ELR STA 706 is located such that an OBSS legacy STA 708 (a non-AP STA that may belong to another BSS that does not support ELR) is within STA ELR coverage of the ELR STA 706. OBSS legacy STAs 708 may be located within STA ELR coverage of STA 702 or outside STA ELR coverage of STA 702. In some configurations, STA 702 and ELR STAs 705 and 706 support ELR and OFDMA. In this case, STA 702 may attempt to become a TXOP holder in the network environment.

The primary difference between the example process 700 and the example process 400 is that a link protection mechanism is applied at the ELR STA 706 to prevent transmission collisions from legacy devices (e.g., OBSS legacy STA 708) during the estimated transmission of STA 702 using legacy CTS frames to enable the OBSS legacy STA 708 to set the NAV. As shown in fig. 7, at operation 710, STA 702 generates an ELR-RTS frame 720 (e.g., MU-RTS transmitted over ELR PPDU structure 300) to reserve the TXOP of STA 702 and broadcasts the ELR RTS frame 720 on a channel to enable legacy STAs 704 and ELR STAs 705 and 706 within the AP ELR coverage to receive the broadcasted ELR RTS frame 720. Upon broadcasting ELR RTS frame 720, STA 702 expects to receive a corresponding ELR CTS from one or more ELR STAs 705 and 706. In some configurations, although the transmission in the example process 700 is a downlink transmission as an example, the procedure of ELR-RTS/CTS transmission may be set for downlink and uplink transmissions.

Once STA 702 broadcasts ELR RTS frame 720, ELR STAs 705 and 706 may receive ELR RTS frame 720 and perform the corresponding operations. Specifically, at operation 740, in response to the ELR RTS frame 720, the ELR STA 706 generates a corresponding ELR CTS frame 750 and transmits the ELR CTS frame 750 over the channel to the STA 702 and OBSS legacy STA 708. Specifically, to initialize OFDMA using MU-RTS frames (i.e., ELR RTS frames 720) in ELR communications, ELR CTS frames 750 may support orthogonal transmissions, e.g., in an RU or encoded domain, allowing STA 702 to separate the sources of ELR CTS frames 750.

Meanwhile, at operation 730, the ELR STA 705 sets a NAV in response to the ELR RTS frame 720. Specifically, upon receiving the ELR RTS frame 720, the ELR STA 705 identifies that the channel will be occupied for a duration (i.e., estimated transmission period), and the ELR STA 705 should refrain from transmitting data on the channel for this duration. Thus, the ELR STA 705 sets a NAV to represent a duration (i.e., estimated transmission period) during which the ELR STA 705 determines that the channel is busy. However, legacy STAs 704 do not understand the broadcasted ELR RTS frame 720 (or any message in the ELR PPDU structure 300 or any message in ELR format). Thus, when the legacy STA 704 receives the ELR RTS frame 720, the legacy STA 704 will not set the NAV, which may cause further collision of reception by the STA 702 on the channel.

Once the ELR STA 706 transmits the ELR CTS frame 750, the ELR STA 706 further transmits a legacy CTS frame 760 to the OBSS legacy STA 708 on the channel as a link protection for the ELR STA 706. Although the OBSS legacy STA 708 does not understand the ELR CTS frame 750 (or any messages in the ELR PPDU structure 300 or any messages in ELR format), the OBSS legacy STA 708 does understand the legacy CTS frame 760. Thus, once the OBSS legacy STA 708 receives the legacy CTS frame 760, at operation 765, the OBSS legacy STA 708 sets a NAV in response to the legacy CTS frame 760. Specifically, upon receiving legacy CTS frame 760, OBSS legacy STA 708 recognizes that the channel will be occupied for a duration (i.e., estimated transmission period), and OBSS legacy STA 708 should refrain from transmitting data on the channel for this duration. Accordingly, the OBSS legacy STA 708 sets a NAV to represent a duration (i.e., estimated transmission period) during which the OBSS legacy STA 708 determines that the channel is busy, thereby avoiding further reception collisions by the ELR STA 706.

Meanwhile, at operation 768, in response to receiving the ELR CTS frame 750, the STA 702 may process the data to be transmitted and generate ELR data (i.e., data in at least one ELR PPDU structure 300). It should be noted that the STA 702 may wait a period of time for the ELR STA 706 to transmit the legacy CTS frame 760.

Upon generation of ELR data, STA 702 transmits ELR data 770 to ELR STA 706. Since the OBSS legacy STA 708 has set the NAV, no collision with the ELR data 770 from the OBSS legacy STA 708 occurs. Upon receiving the ELR data 770, the ELR STA 706 transmits a corresponding ELR acknowledgement (ELR-ACK) back to the STA 702. However, at operation 790, the legacy STAs 704 may still be concurrently transmitting data to the STA 702, potentially colliding with the ELR-ACK 780.

In contrast to the example process 400, the example process 700 employs a link protection mechanism applied at the ELR STA 706, using a legacy CTS frame 760, which may prevent collisions with ELR data 770 from the OBSS legacy STA 708. However, a potential collision of ELR-ACK 780 at STA 702 is still possible.

Fig. 8 illustrates an example procedure for RTS/CTS transmission by the AP and ELR STAs of fig. 7. As shown, the AP 802 (i.e., STA 702) generates and broadcasts an ELR RTS frame 820 (i.e., ELR RTS frame 720). At the ELR STA 804 (i.e., the ELR STA 706), after receiving the broadcasted ELR RTS frame 820 and waiting for a SIFS time, the ELR STA 804 transmits an ELR CTS frame 830 (i.e., the ELR CTS frame 750). Then, after waiting for another SIFS time, the ELR STA 804 transmits a legacy CTS frame 840 (i.e., legacy CTS frame 760). At the AP 802, after receiving the ELR CTS 830 and waiting for a period of time of the legacy CTS frame 840 and another SIFS time, the AP 802 generates and transmits an ELR PPDU(s) 850 (i.e., ELR data 770). Then, at the ELR STA 804, after receiving the ELR PPDU(s) 850 and waiting for another SIFS time, the ELR STA 804 transmits an ELR ACK 860 (i.e., ELR ACK 780). In some embodiments, each SIFS time may be 16 μs. In some configurations, in an ELR BSS, the ELR-NAV superstrate is (3×aSIFSTime) + (ELR-CTS_Time) + (LG-CTS_Time) + aRxPHYStartDelay + (2×aSlotTime).

Fig. 9 illustrates an example procedure for ELR-RTS/CTS transmission for STAs with full link protection. STA 902 may be an AP. Similar to the example process 700, in the example process 900, the STA 902 (i.e., the AP 110) is located in a position where a legacy STA 904 (which may be a non-AP STA that does not support ELR, such as the ER STA 120) and two ELR STAs 905 and 906 (which may be non-AP STAs that support ELR, such as the ELR STA 130) are within STA ELR coverage of the STA 902. The distance of each ELR STA 905 and 906 from STA 902, respectively, requires an ELR PPDU to carry the RTS/CTS frame. In addition, the ELR STA 906 is located at a position such that an OBSS legacy STA 908 (a non-AP STA that may belong to another BSS that does not support ELR) is within STA ELR coverage of the ELR STA 906. The OBSS legacy STAs 908 may be located within the STA ELR coverage of the STA 902 or outside the STA ELR coverage of the STA 902. In some configurations, the STA 902 and ELR STAs 905 and 906 support ELR and OFDMA. In this case, STA 902 may attempt to become a TXOP holder in the network environment.

The primary difference between the example process 900 and the example process 700 is that in addition to applying a link protection mechanism at the ELR STA 906 that uses a legacy CTS frame, an additional link protection mechanism is applied at the STA 902 that uses a legacy CTS-to-self mechanism to prevent collision of transmissions from legacy devices (e.g., legacy STA 904) during the estimated transmission of the STA 902 so that transmissions on both the STA 902 and ELR STA 906 have full link protection. Specifically, in the CTS-to-self mechanism, STA 902 transmits a legacy CTS frame without a look-ahead RTS frame using the legacy 802.11b STA's modulation technique, so that legacy STAs that do not support ELR (e.g., legacy STA 904) can learn that there will be a transmission when receiving the legacy CTS frame, which will cause the legacy device to set the NAV.

As shown in fig. 9, prior to transmitting the ELR RTS frame, STA 902 transmits a legacy CTS-to-self frame 910 to legacy STA 904 on the channel using the CTS-to-self mechanism as a link protection for STA 902. Upon receiving the legacy CTS frame 910, the legacy STA 904 may set the NAV. Specifically, upon receiving legacy CTS frame 910, legacy STA 904 recognizes that the channel will be occupied for a duration (i.e., estimated transmission period), and legacy STA 904 should refrain from transmitting data on the channel for this duration. Thus, legacy STA 904 sets a NAV to indicate the duration of the channel busy, thereby avoiding further reception collisions by STA 902.

At operation 915, after transmitting the legacy CTS frame 910, the STA 902 generates an ELR-RTS frame 920 (e.g., MU-RTS transmitted through the ELR PPDU structure 300) to reserve the TXOP of the STA 902 and broadcasts the ELR RTS frame 920 on a channel such that legacy STAs 904 and ELR STAs 905 and 906 within the coverage of the AP ELR receive the broadcasted ELR RTS frame 920. Upon broadcasting the ELR RTS frame 920, the STA 902 expects to receive a corresponding ELR CTS frame from one or more ELR STAs 905 and 906. In some configurations, although the transmissions in the example process 900 are downlink transmissions as an example, the procedure for ELR-RTS/CTS transmissions may be set for downlink and uplink transmissions.

Once STA 902 broadcasts ELR RTS frame 920, ELR STAs 905 and 906 may receive ELR RTS frame 920 and perform the corresponding operations. Specifically, at operation 940, in response to the ELR RTS frame 920, the ELR STA 906 generates a corresponding ELR CTS frame 950 and transmits the ELR CTS frame 950 over a channel to the STA 902 and OBSS legacy STA 908. Specifically, to initialize OFDMA using MU-RTS frames (i.e., ELR RTS frames 920) in ELR communications, ELR CTS frames 950 may support orthogonal transmissions, e.g., in an RU or encoded domain, allowing STAs 902 to separate sources of ELR CTS frames 950.

Meanwhile, at operation 930, the ELR STA 905 sets a NAV in response to the ELR RTS frame 920. Specifically, upon receiving the ELR RTS frame 920, the ELR STA 905 identifies that the channel will be occupied for a duration (i.e., estimated transmission period) and that the ELR STA 905 should refrain from transmitting data on the channel for this duration. Thus, the ELR STA 905 sets a NAV to represent a duration (i.e., estimated transmission period) during which the ELR STA 905 determines that the channel is busy. On the other hand, although the legacy STA 904 does not understand the broadcasted ELR RTS frame 920 (or any message in the ELR PPDU structure 300 or any message in ELR format), the legacy STA 904 does not need to set the NAV in response to the ELR RTS frame 920 because the legacy STA 904 has already set the NAV in the early operation 912 as a response to the legacy CTS frame 910.

Once the ELR STA 906 transmits the ELR CTS frame 950, the ELR STA 906 further transmits a legacy CTS frame 960 to the OBSS legacy STA 908 on a channel as a link protection for the ELR STA 906. Although the OBSS legacy STA 908 does not understand the ELR CTS frame 950 (or any messages in the ELR PPDU structure 300 or any messages in ELR format), the OBSS legacy STA 908 does understand the legacy CTS frame 960. Thus, once the legacy CTS frame 960 is received by the legacy STA 908, the legacy STA 908 sets a NAV in response to the legacy CTS frame 960 at operation 965. Specifically, upon receiving the legacy CTS frame 960, the OBSS legacy STA 908 recognizes that the channel will be occupied for a duration (i.e., estimated transmission period), and the OBSS legacy STA 908 should refrain from transmitting data on the channel for this duration. Accordingly, the OBSS legacy STA 908 sets a NAV to indicate the duration of the channel busy, thereby avoiding further reception collisions by the ELR STA 906.

Meanwhile, at operation 968, in response to receiving the ELR CTS frame 950, the STA 902 may process the data to be transmitted and generate ELR data (i.e., data in at least one ELR PPDU structure 300). It should be noted that the STA 902 may wait a period of time for the ELR STA 906 to transmit the legacy CTS frame 960.

Once the ELR data is generated, the STA 902 transmits the ELR data 970 to the ELR STA 906 over the channel. Since the OBSS legacy STA 908 has set the NAV, no collision with the ELR data 970 occurs from the OBSS legacy STA 908. Upon receiving the ELR data 970, the ELR STA 906 transmits a corresponding ELR acknowledgement (ELR-ACK) back to the STA 902. Since the legacy STA 904 has set the NAV, no collision with the ELR-ACK 980 occurs from the legacy STA 904.

In contrast to the example process 700, the example process 900 further employs a link protection mechanism applied at the STA 902, using a legacy CTS frame 910 (i.e., CTS-to-self mechanism), which may prevent collisions with ELR data 970 from the OBSS legacy STA 908. Further, the example process 900 applies a link protection mechanism at the ELR STA 906 that uses the legacy CTS frame 960 to ensure that collisions with ELR data 970 from the OBSS legacy STA 908 can be prevented.

It should be noted that in the example processes 700 and 900, each ELR STA 705/905 and 706/906 may use the information in the broadcasted ELR RTS frame 720/920 as the most current basis for updating its NAV settings, and an ELR STA (e.g., ELR STA 705/905, or any other ELR device receiving the broadcasted ELR RTS frame 720/920) that uses the information in the broadcasted ELR RTS frame 720/920 as the most current basis for updating its NAV settings allows its NAV to be reset if no PHY-rxearlyig or PHY-rxstart. Indication primitive is received from the PHY during the time that the MAC receives the ELR-NAVTimeout from the PHY beginning with the PHY-rxend. Indication primitive corresponding to the detected ELR-RTS frame 720/920.

Fig. 10 shows an example procedure of RTS/CTS transmission by the AP and ELR STA in fig. 9. As shown, the AP1002 (i.e., STA 902) generates and transmits a legacy CTS frame 1010 (i.e., legacy CTS frame 910) as a CTS-to-self mechanism. After waiting for one SIFS duration, the AP1002 generates and broadcasts an ELR RTS frame 1020 (i.e., ELR RTS frame 920). At the ELR STA 1004 (i.e., the ELR STA 906), after receiving the broadcasted ELR RTS frame 1020 and waiting for one SIFS duration, the ELR STA 1004 transmits an ELR CTS frame 1030 (i.e., the ELR CTS frame 950). Then, after waiting for another SIFS duration, the ELR STA 1004 transmits a legacy CTS frame 1040 (i.e., legacy CTS frame 960). At the AP1002, after receiving the ELR CTS1030 and waiting for a period of time and another SIFS duration of the legacy CTS frame 1040, the AP1002 transmits an ELR PPDU(s) 1050 (i.e., ELR data 970). Then, at the ELR STA 1004, after receiving the ELR PPDU(s) 1050 and waiting for yet another SIFS duration, the ELR STA 1004 transmits an ELR ACK 1060 (i.e., ELR ACK 980). In some embodiments, each SIFS duration may be 16 μs. In some configurations, in an ELR BSS, the ELR-NAV superstrate is (3×aSIFSTime) + (ELR-CTS_Time) + (LG-CTS_Time) + aRxPHYStartDelay + (2×aSlotTime).

In the example processes 700 and 900, the transmission is a downlink transmission because ELR data is transmitted by the STAs 702/902 to the ELR STAs 706/906. On the other hand, the link protection mechanism may also be adapted for uplink transmission, wherein ELR data is transmitted by the ELR STA to the AP.

Fig. 11 illustrates an example procedure for ELR-RTS/CTS transmission by an ELR STA with link protection. The ELR STA 1106 may be a non-AP STA supporting ELR. In the example process 1100, an AP 1102 (i.e., AP 110) is located in a position where a legacy STA 1104 (which may be a non-AP STA that does not support ELR, such as ER STA 120) and two ELR STAs 1105 and 1106 (which may be non-AP STAs that support ELR, such as ELR STA 130) are within the coverage of the AP 1102. The distance of each ELR STA 1105 and 1106, respectively, from the AP 1102 requires an ELR PPDU to carry the RTS/CTS frame. In addition, the ELR STA 1106 is located such that an OBSS legacy STA 1108 (a non-AP STA that may belong to another BSS that does not support ELR) is within the ELR coverage of the non-AP STA ELR of the ELR STA 1106. OBSS legacy STAs 1108 may be located within the coverage of the AP 1102 or outside the coverage of the AP 1102. In some configurations, the AP 1102 and ELR STAs 1105 and 1106 support ELR and OFDMA. In this case, the ELR STA 1106 may attempt to become a TXOP holder in the network environment.

In the example process 1100, a link protection mechanism is applied at the ELR STA 1106 that prevents transmission collisions from legacy non-AP STAs (e.g., OBSS legacy STA 1108) during an estimated transmission by the ELR STA 1106 using a legacy CTS-to-self mechanism. Specifically, in the CTS-to-self mechanism, the ELR STA 1106 transmits a legacy CTS frame without a look-ahead RTS frame using the modulation technique of the legacy 802.11b device, so that a legacy non-AP STA (e.g., OBSS legacy STA 1108) can learn that there will be a transmission when receiving the legacy CTS frame, which will cause the legacy non-AP STA to set the NAV.

As shown in fig. 11, prior to transmitting the ELR RTS frame, the ELR STA 1106 transmits a legacy CTS-to-self frame 1110 as a link protection for the ELR STA 1106 over a channel to the OBSS legacy STA 1108 (or any legacy non-AP STA within ELR coverage of a non-AP STA of the ELR STA 1106). Upon receiving the legacy CTS frame 1110, the OBSS legacy STA 1108 recognizes that the channel will be occupied for a duration (i.e., during the estimated transmission), and the OBSS legacy STA 1108 should refrain from transmitting data on the channel for this duration. Thus, at operation 1120, the OBSS legacy STA 1108 sets a NAV that represents a duration during which the OBSS legacy STA 1108 determines that the channel is busy, thereby avoiding further reception collisions by the ELR STA 1106.

At operation 1130, after transmitting the legacy CTS frame 1110, the ELR STA 1106 generates an ELR-RTS frame 1140 (e.g., MU-RTS transmitted over the ELR PPDU structure 300) to reserve the TXOP of the ELR STA 1106 and transmits the ELR RTS frame 1140 to the AP 1102 (and OBSS legacy STA 1108) on a channel. Upon transmission of the ELR RTS frame 1140, the ELR STA 1106 expects to receive a corresponding ELR CTS frame from the AP 1102.

Once the ELR STA 1106 transmits the ELR RTS frame 1140, the ap 1102 may receive the ELR RTS frame 1140 and perform the corresponding operations. In some configurations, because of the transmission power imbalance between the AP 1102 and the non-AP STAs (i.e., ELR STAs 1106) of up to 6dB, if a legacy CTS frame can arrive at the ELR STA 1106 (e.g., when the ELR STA 1106 is within non-HT coverage of the AP 1102), the AP 1102 may respond to the ELR RTS frame 1140 with only the legacy CTS frame. In other words, the AP 1102 may choose not to generate and transmit an ELR CTS frame in response to the ELR RTS frame 1140. In operation 1150, the AP 110, in response to the ELR RTS frame 1140, the AP 1102 may generate a corresponding legacy CTS frame 1160 and transmit the legacy CTS frame 1160 over the channel to the ELR STAs 1105 and 1106 and legacy STA 1104. In other words, the ELR STAs 1105 and 1106 and the legacy STA 1104 will receive the legacy CTS frame 1160. In some configurations, the AP 1102 may choose to generate and transmit a dual CTS frame to the ELR STAs 1105 and 1106 and the legacy STA 1104, which may include the ELR CTS frame and the legacy CTS frame.

In operation 1162, the ELR STA 1105 sets a NAV in response to the legacy CTS frame 1160. Specifically, upon receiving the legacy CTS frame 1160, the ELR STA 1105 recognizes that the channel will be occupied for a duration (i.e., estimated transmission period) and that the ELR STA 1105 should refrain from transmitting data on the channel for this duration. Thus, the ELR STA 1105 sets the NAV to indicate the duration of channel busy (i.e., estimated transmission period). On the other hand, legacy STA 1104 understands legacy CTS frame 1160. Thus, in response to the legacy CTS frame 1160, the legacy STA 1104 sets a NAV to indicate the duration of channel busy (i.e., estimated transmission period) in operation 1165.

On the other hand, in operation 1168, the data to be transmitted may be processed and ELR data (i.e., data in the at least one ELR PPDU structure 300) may be generated in response to receiving the legacy CTS frame 1160,ELR STA 1106. The ELR data 1170 is transmitted to the AP 1102 once the ELR data 1170,ELR STA 1106 is generated. Since the legacy STA 1104 has set the NAV, no collision of the legacy STA 1104 with the ELR data 1170 occurs. Upon receiving the ELR1170 data, the AP 1102 sends a corresponding Acknowledgement (ACK) to the ELR STA 1106. Specifically, ACK1180 may be a conventional ACK due to a transmission power imbalance between the AP 1102 and the non-AP STA (i.e., the ELR STA 1106) reaching 6 dB. Since the OBSS legacy STA 1108 has set the NAV, no collision from the OBSS legacy STA 1108 with the ACK1180 will occur.

Fig. 12 illustrates an example procedure for RTS/CTS transmission by the AP and ELR STAs of fig. 11. As shown, ELR STA 1204 (i.e., ELR STA 1106) sends a legacy CTS frame 1210 (i.e., legacy CTS frame 1110) as a CTS-to-self mechanism. After waiting for a short inter-frame space (SIFS) duration, ELR STA 1204 sends an ELR RTS frame 1220 (i.e., ELR RTS frame 1140). At the AP 1202 (i.e., AP 1102), after receiving the ELR RTS frame 1220 and waiting for a SIFS duration, the AP 1202 may send a legacy CTS frame 1240 (i.e., legacy CTS frame 1160). At the ELR STA 1204, after receiving the legacy CTS frame 1240 and waiting for another SIFS duration, the ELR STA 1204 generates and transmits an ELR PPDU(s) 1250 (i.e., ELR data 1170). Then, at the AP 1202, after receiving the ELR PPDU(s) 1250 and waiting for another SIFS duration, the AP 1202 sends a legacy ACK 1260 (i.e., legacy ACK 1180). In some embodiments, each SIFS duration may be 16 μs. The timeout period used may be a NAV timeout period or an ELR-NAV timeout period, depending on the performance (e.g., power, packet error rate) of the received ELR-RTS. In some configurations, the NAV superstrate may be (2×aSIFSTime) + (LG-CTS_Time) + aRxPHYStartDelay + (2×aSlotTime).

Fig. 13 shows an example procedure for RTS/CTS transmission by an ELR STA with link protection, where the AP is a legacy AP. ELR STA 1306 may be a non-AP STA that supports ELR. In the example process 1300, the AP 1302 (i.e., the AP 110) may be an ELR-enabled AP (i.e., an ELR-enabled AP) that is located at a position where the legacy STA 1304 (which may be a non-AP STA that does not support ELR, such as the ER STA 120) and the two ELR STAs 1305 and 1306 (which may be non-AP ELR-enabled STAs, such as the ELR STA 130) are within the AP coverage of the AP 1302. In addition, the ELR STA 1306 is located such that the OBSS legacy STA 1308 (which may be a non-AP STA belonging to another BSS that does not support ELR) is within the non-AP STA ELR coverage of the ELR STA 1306. OBSS legacy STAs 1308 may be located within the AP coverage of the AP 1302 or outside the AP coverage of the AP 1302. In some configurations, ELR STAs 1305 and 1306 support ELR and OFDMA. In this case, the AP 1302 may attempt to become a TXOP holder in a network environment, and the ELR STA 1306 is a STA that receives data from the TXOP holder (i.e., the AP 1302).

The main difference between the example process 1300 and the previous example processes (e.g., example processes 700 and 900) is that the ELR-enabled AP 1302 (i.e., ELR-enabled AP) may choose to send a legacy RTS frame instead of an ELR RTS frame due to the transmission power imbalance between the AP 1302 and the non-AP STAs (i.e., ELR STAs 1306) reaching 6 dB. As shown in fig. 13, in operation 1315, the AP 1302 generates a legacy RTS frame 1320 that is not transmitted through the ELR PPDU structure 300 to reserve the TXOP of the AP 1302 and broadcasts the legacy RTS frame 1320 on a channel so that legacy STAs 1304 and ELR STAs 1305 and 1306 within the AP coverage can receive the broadcasted legacy RTS frame 1320. Upon broadcasting the legacy RTS frame 1320, the AP 1302 expects to receive a corresponding ELR CTS frame or legacy CTS frame from one or more of the legacy STAs 1304 and ELR STAs 1305 and 1306. In some configurations, although the transmission in the example process 1300 is a downlink transmission as an example, the process of RTS/CTS transmission may be set for downlink and uplink transmissions.

Once the AP 1302 broadcasts the legacy RTS frame 1320, the legacy STAs 1304 and ELR STAs 1305 and 1306 may receive the legacy RTS frame 1320 and perform corresponding operations. Specifically, in operation 1330, the ELR STA 1305 sets a NAV in response to the legacy RTS frame 1320. Specifically, upon receiving the legacy RTS frame 1320, the ELR STA 1305 recognizes that the channel will be occupied for a duration (i.e., estimated transmission period) and the ELR STA 1305 should refrain from transmitting data on the channel for this duration. Thus, the ELR STA 1305 sets a NAV to indicate the duration of channel busy (i.e., estimated transmission period). Similarly, in operation 1335, the legacy STA 1304 sets a NAV as well in response to the legacy RTS frame 1320. Specifically, upon receiving the legacy RTS frame 1320, the legacy STA 1304 recognizes that the channel will be occupied for a duration (i.e., estimated transmission period), and the legacy STA 1304 should refrain from transmitting data on the channel for this duration. Thus, the legacy STA 1304 sets a NAV to indicate the duration of channel busy (i.e., estimated transmission period).

Meanwhile, at operation 1340, in response to the legacy RTS frame 1320, the ELR STA 1306 generates a dual CTS frame including a corresponding ELR CTS frame 1350 and legacy CTS frame 1360. The ELR STA 1306 then transmits an ELR CTS frame 1350 and a legacy CTS frame 1360 over the channel to the AP 1302 and OBSS legacy STA 1308. It should be noted that although fig. 13 shows the ELR CTS frame 1350 transmitted before the legacy CTS frame 1360, it is also possible that the legacy CTS frame 1360 is transmitted before the ELR CTS frame 1350. In other words, the ELR STA 1306 may transmit the dual CTS frames in any order.

At the OBSS legacy STA 1308, although the OBSS legacy STA 1308 does not understand the ELR CTS frame 1350 (or any message in the ELR PPDU structure 300 or any message in ELR format), the OBSS legacy STA 1308 may understand the legacy CTS frame 1360. Thus, once the legacy CTS frame 1360 is received by the legacy STA 1308, at operation 1365, the legacy STA 1308 sets a NAV in response to the legacy CTS frame 1360. Specifically, upon receiving the legacy CTS frame 1360, the OBSS legacy STAs 1308 recognize that the channel will be occupied for a duration (i.e., during the estimated transmission), and that the OBSS legacy STAs 1308 should refrain from transmitting data on the channel for this duration. Accordingly, the OBSS legacy STA 1308 sets a NAV to indicate the duration of the channel busy to avoid further reception collisions by the ELR STA 1306.

Meanwhile, at operation 1368, the AP 1302 may process data to be transmitted and generate data in response to receiving the ELR CTS frame 750 and the legacy CTS frame 760. Specifically, once the AP 1302 receives the legacy CTS frame 1360, the AP 102 generates data, which may be in ELR format or legacy format, at operation 1368.

Once the data is generated, the AP 1302 sends the data 1370 to the ELR STA 1306. Since the OBSS legacy STA 1308 has set the NAV, no collision from the OBSS legacy STA 1308 with the data 1370 occurs. Upon receiving the data 1370, the ELR STA 1306 sends a corresponding acknowledgement (which may be an ACK in ELR format) to the AP 1302. Since the legacy STA 1304 and the ELR STA 1305 have both set NAVs, collisions from the legacy STA 1304 and the ELR STA 1305 with the ACK 1380 do not occur.

In some configurations, the ELR STA 1306 may choose to generate and transmit an ELR CTS frame (i.e., ELR CTS frame 1350) in response to the legacy RTS frame 1320 instead of transmitting a dual CTS frame. In this case, the OBSS legacy STA 1308 will not understand the ELR CTS frame 1350. Therefore, the OBSS legacy STA 1308 will not set the NAV.

Fig. 14 shows an example procedure of RTS/CTS transmission of the AP and ELR STA in fig. 13. As shown, AP 1402 (i.e., AP 1302) generates and broadcasts a legacy RTS frame 1420 (i.e., legacy RTS frame 1320). At the ELR STA 1404 (i.e., ELR STA 1306), after receiving the broadcasted legacy RTS frame 1420 and waiting for a SIFS time, the ELR STA 1404 generates and transmits a dual CTS frame including an ELR CTS frame 1430 (i.e., ELR CTS frame 1350) and a legacy CTS frame 1440 (i.e., legacy CTS frame 1360). In some implementations, the ELR STA 1404 may wait for another SIFS time between transmitting the ELR CTS frame 1430 and the legacy CTS frame 1440. At the AP 1402, after receiving the ELR CTS frame 1430 and the legacy CTS frame 1440 and waiting for another SIFS time, the AP 1402 generates and transmits a PPDU(s) 1450 (i.e., data 1370, which may be in ELR format or legacy format). Then, at the ELR STA 1404, after receiving the PPDU(s) 1450 and waiting for another SIFS time, the ELR STA 1404 generates and transmits an ACK 1460 (i.e., ACK 1380, which may be in ELR format). In some embodiments, each SIFS time may be 16 μs.

In some configurations, a link protection mechanism using a legacy CTS frame in a CTS-to-self mechanism allows a legacy non-AP STA to NAV protect and prevents the legacy non-AP STA from resetting the NAV before the desired TXOP ends. However, if the corresponding CTS frame is not sent for ELR RTS frames, the legacy non-AP STA will not be able to reset the NAV. In this case, the TXOP may be terminated or truncated using the CF-end frame. For example, in some configurations, after transmitting the ELR RTS frame, the TXOP holder may send a legacy CF-end frame to terminate the TXOP if no legacy CTS frame or ELR CTS frame is received during the estimated transmission period. In some configurations, if the TXOP holder determines that there are no more data frames to transmit, the TXOP holder may send a dual CF-end frame including a legacy CF-end frame and an ELR CF-end frame to truncate the TXOP. For example, the TXOP holder may transmit a legacy CF-end frame to a legacy STA and an ELR CF-end frame to an ELR STA. In some configurations, there may be one SIFS time between transmitting the legacy CF-end frame and transmitting the ELR CF-end frame.

In some configurations, the AP may set the TXOP duration RTS threshold based on the total PPDU duration, coverage, estimated collision and retransmission opportunities it transmits. For example, the TXOP duration RTS threshold in ELR operation may reuse some of the definitions in the HE operation element, where the value may be (1) a value between 1 and 1022 to enable the TXOP duration-based RTS/CTS exchange with its associated STA, or (2) 1023 to disable the TXOP duration-based RTS/CTS exchange with its associated STA. The unit of RTS threshold is 32 microseconds.

In the discussed link protection mechanism, various considerations are discussed in terms of the location of the ELR STA (either within or outside the non-HT coverage of the AP). Based on a variety of circumstances, the RTS/CTS content in ELR may need to be modified. For example, an ELR RTS frame (i.e., an RTS frame carried in ELR format) may add an additional indicator to indicate the total CTS duration (including ELR CTS and LG CTS, if present). Accordingly, the ELR device may update its NAVTimeout duration accordingly. For example, if collisions and retransmissions occur frequently, the TXOP initiator/holder may (1) decrease the RTS threshold and/or (2) enable subsequent LG-CTS. In some configurations, the ELR-NAV superstrate should be set to (3×asifstime) + (ELR-cts_time) + (LG-cts_time) + aRxPHYStartDelay + (2×alslottime) under full link protection.

Fig. 15 illustrates an example communication system 1500 that includes two devices 1510 and 1520. Each of the devices 1510 and 1520 may perform various functions to implement the schemes, techniques, procedures, and methods described herein with respect to channel switching operations, including the schemes described above with respect to various proposed designs, concepts, schemes, systems, and methods, and procedures described below, such as the device 1510 in the AP 110 shown in fig. 1 and the device 1520 in the non-AP STA (i.e., ER STA 120 and/or ELR STA 130) shown in fig. 1.

Each device 1510 and 1520 may be part of an electronic device, which may be a non-transmission point station (non-AP STA) or a transmission point (AP), such as a portable or mobile device, a wearable device, a wireless communication device, or a computing device. When implemented in a non-AP STA, each of the devices 1510 and 1520 may be implemented in a smart phone, a smart watch, a personal digital assistant, a digital camera, or a computing device (e.g., tablet, notebook). Each device 1510 and 1520 may also be part of a machine type device, which may be an internet of things (IoT) device, such as a fixed or stationary device, home device, wired communication device, or computing device. For example, each device 1510 and 1520 may be implemented as a smart thermostat, a smart refrigerator, a smart door lock, a wireless speaker, or a home control center. When implemented in a network device, device 1510 and/or device 1520 may be implemented as a network node, such as a transmission point in a WLAN.

In certain embodiments, each device 1510 and 1520 may be implemented in the form of one or more Integrated Circuit (IC) chips, such as, but not limited to, one or more single-core processors, one or more multi-core processors, one or more Reduced Instruction Set (RISC) processors, or one or more Complex Instruction Set (CISC) processors. In the above scenario, each device 1510 and 1520 may be implemented as or as a non-AP STA or AP. Each device 1510 and 1520 may include at least some of the components shown in fig. 15, such as processor 1512 and processor 1522. Each device 1510 and 1520 may also include one or more other components (e.g., internal power supplies, display devices, and/or user interface devices) that are not relevant to the proposed solution of the present disclosure, and thus, for brevity, such components of devices 1510 and 1520 are not shown in fig. 15 nor described below.

In some embodiments, processor 1512 and processor 1522 may be implemented in the form of one or more single-core processors, one or more multi-core processors, one or more RISC processors, or one or more CISC processors. That is, although the singular "one processor" is used herein to refer to the processors 1512 and 1522, in some implementations, the processors 1512 and 1522 may include multiple processors, and in other implementations may include a single processor. In certain embodiments, processor 1512 and processor 1522 may be implemented in hardware (and optionally firmware) with electronic components including, but not limited to, one or more transistors, one or more diodes, one or more capacitors, one or more resistors, one or more inductors, one or more memories, and/or one or more variable capacitance diodes configured and arranged to perform a particular function in accordance with a particular purpose of the present disclosure. In other words, in certain embodiments, processor 1512 and processor 1522 are a special purpose machine specifically designed, arranged, and configured to perform certain tasks in wireless communications related to system parameter transmission schemes consistent with various implementations of the present disclosure.

In some embodiments, device 1510 may further include a memory 1514 coupled to processor 1512, processor 1512 having access to memory 1514 and storing data therein. In some implementations, the device 1520 may also include a memory 1524 coupled to the processor 1522, the processor 1522 having access to the memory 1524 and storing data therein. Each memory 1514 and 1524 may include a type of Random Access Memory (RAM), such as Dynamic RAM (DRAM), static RAM (SRAM), thyristor RAM (T-RAM), and/or zero capacitance RAM (Z-RAM). Additionally or alternatively, each memory 1514 and 1524 can include a type of Read Only Memory (ROM), such as a mask ROM, a Programmable ROM (PROM), an Erasable Programmable ROM (EPROM), and/or an Electrically Erasable Programmable ROM (EEPROM). Additionally or alternatively, each memory 1514 and 1524 may include a type of non-volatile random access memory (NVRAM), such as flash memory, solid state memory, ferroelectric RAM (FeRAM), magnetoresistive RAM (MRAM), and/or phase change memory.

In some embodiments, the device 1510 may further include a transceiver 1516 coupled to the processor 1512. The transceiver 1516 may include a transmitter capable of wireless transmission and a receiver capable of wireless reception of data. In some embodiments, the device 1520 may also include a transceiver 1526 coupled to the processor 1522. The transceiver 1526 may include a transmitter capable of wireless transmission and a receiver capable of wireless reception of data.

Each device 1510 and 1520 may be one communication entity capable of communicating with each other using the various proposed schemes described in this disclosure. In some embodiments, device 1510 may serve the role of AP 110 and device 1520 may serve the role of a non-AP STA (e.g., ER STA 120 and/or ELR STA 130) to perform the described methods, procedures, and schemes.

Fig. 16 is a flowchart of a wireless communication method (procedure) of the STA. The method may be performed by a STA (e.g., STA 702, STA 902, ELR STA 1106, AP 1302). Optionally, at operation 1610, the STA transmits a CTS-to-Self frame in a non-ELR format before transmitting the RTS frame. At operation 1620, the STA transmits an RTS frame in ELR format to acquire a TXOP. At operation 1630, the STA receives a first CTS frame in ELR format or non-ELR format in response to the RTS frame. At operation 1640, in response to receiving the first CTS frame, the STA transmits data in ELR format within the TXOP. Optionally, at operation 1650, the STA further receives an acknowledgement of the same format as the first CTS frame in response to the data being transmitted.

In some configurations, the STA waits for a period of time in response to receiving the first CTS frame. The STA receives the second CTS frame in this period. One of the first CTS frame and the second CTS frame is in ELR format, and the other of the first CTS frame and the second CTS frame is in non-ELR format. The data is sent after the period of time.

In some configurations, the STA transmits a single CF-end frame or a double CF-end frame to terminate the TXOP in response to not receiving any CTS frame or fully transmitting data in ELR format within an estimated transmission period. The single CF-end frame is in a non-ELR format. The dual CF-end frames include a first CF-end frame in a non-ELR format and a second CF-end frame in an ELR format.

Fig. 17 is a flowchart of a wireless communication method (procedure) of the STA. The method may be performed by an STA (e.g., ELR STA 706, ELR STA 906, AP 1102, ELR STA 1306). At operation 1710, the STA receives an RTS frame in ELR format or non-ELR format. At operation 1720, the STA transmits a single CTS frame or a dual CTS frame on the channel in response to the RTS frame. The dual CTS frames include a primary CTS frame in ELR format and a secondary CTS frame in non-ELR format. At operation 1730, the STA receives data on a channel. In response to receiving the data, the STA transmits an acknowledgement of the response data on the channel at operation 1740. The acknowledgement is in the same format as the first CTS frame of either a single CTS frame or a double CTS frame in response to the RTS frame.

It is to be understood that the specific order or hierarchy disclosed in the flowcharts is an illustration of exemplary approaches. It will be appreciated that the specific order or hierarchy in the flowcharts may be rearranged based on design preferences. Further, some blocks may be combined or omitted. The accompanying method claims present elements of the various blocks in a sample order, and are not meant to be limited to the specific order or hierarchy.

The preceding description is intended to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular does not mean "one" unless specifically so stated, but rather "one or more". The term "exemplary" as used herein means "serving as an example, instance, or illustration. Any aspect described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other aspects. The term "some" means one or more unless specifically indicated. Combinations such as "at least one A, B or C", "one or more A, B or C", "at least one A, B and C", "one or more A, B and C", and "A, B, C or any combination" include any combination of A, B and/or C, and may include multiples of a, multiples of B, or multiples of C. Specifically, combinations such as "at least one A, B or C", "one or more A, B or C", "at least one A, B and C", "one or more A, B and C", and "A, B, C or any combination" may be a alone, B alone, C, A and B, A and C, B and C, or a and B and C, wherein such combinations may comprise one or more members of A, B or C. All structural and functional equivalents to the various aspects described in the disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Furthermore, nothing disclosed herein is intended to be dedicated to the public of made a public possession regardless of whether such disclosure is explicitly recited in the claims. Words such as "module," mechanism, "" element, "" device, "and the like may not be substituted for the word" means. Thus, any claim element should not be construed as a "means" in addition to a functional language unless the element is explicitly recited in the phrase "means for.

Claims (20)

1.A method of a wireless communication station STA, characterized by: comprising the following steps:

Sending Request To Send (RTS) frames in an enhanced long-distance ELR format to acquire transmission opportunities (TXOPs);

Receiving a first clear to send, CTS, frame in response to the RTS frame, the first CTS frame being in ELR format or non-ELR format; and

In response to receiving the first CTS frame, data is transmitted in ELR format within the TXOP.

2. The method according to claim 1, characterized in that: further comprises:

an acknowledgement is received in response to the data being transmitted, the acknowledgement being in the same format as the first CTS frame.

3. The method according to claim 1, characterized in that: further comprises:

Before sending the RTS frame, sending a CTS-to-self frame in a non-ELR format.

4. The method according to claim 1, characterized in that: further comprises:

waiting a period of time in response to receiving the first CTS frame; and

A second CTS frame is received within the period of time,

Wherein one of the first CTS frame and the second CTS frame is in ELR format and the other is in non-ELR format;

wherein the transmission of data is after the period of time.

5. The method according to claim 1, characterized in that: further comprises:

In response to not receiving any CTS frame or completely transmitting data in ELR format within an estimated transmission period, a single CF-end frame or a double CF-end frame is transmitted to terminate the TXOP.

6. The method according to claim 5, wherein: the single CF-end frame is in a non-ELR format.

7. The method according to claim 5, wherein: the dual CF-end frame includes a first CF-end frame in a non-ELR format and a second CF-end frame in an ELR format.

8. The method according to claim 1, characterized in that: the RTS frame and the first CTS frame of the ELR format support single-user SU or multi-user MU orthogonal frequency division multiple access OFDMA.

9. The method according to claim 8, wherein: the first CTS frame of the ELR format supporting multi-user MU orthogonal frequency division multiple access OFDMA also supports CTS separation by non-overlapping resource units RU or orthogonal codes.

10. The method according to claim 1, characterized in that: wherein the ELR format is an ELR physical layer protocol data unit PPDU structure and the ELR physical layer PPDU structure includes one or more general signal fields, an ELR short training field STF, an ELR long training field LTF, an ELR signal field, and an ELR data field.

11. A method of a wireless communication station STA, characterized by: comprising the following steps:

Receiving a request to send RTS frame in an enhanced long range ELR format or a non-ELR format on a channel;

Transmitting a single CTS frame or a dual CTS frame on a channel responsive to said RTS frame, said dual CTS frame including a first CTS frame in ELR format and a second CTS frame in non-ELR format;

Receiving data over a channel; and

An acknowledgement is sent on the channel in response to the received data in the same format as the first CTS frame of the single CTS frame or the dual CTS frame of the responsive RTS frame.

12. The method according to claim 11, wherein: the single CTS frame may be in ELR format when the RTS frame is in a non-ELR format, and ELR format or non-ELR format when the RTS frame is in ELR format.

13. The method according to claim 11, wherein: the CTS frame in ELR format supports single-user SU or multi-user MU orthogonal frequency division multiple access OFDMA.

14. The method according to claim 13, wherein: the CTS frame in ELR format supporting MU OFDMA also supports CTS separation by non-overlapping resource units RUs or orthogonal codes.

15. The method according to claim 11, wherein: the ELR format is an ELR physical layer protocol data unit PPDU structure, and the ELR physical layer PPDU structure includes one or more general signal fields, an ELR short training field STF, an ELR long training field LTF, an ELR signal field, and an ELR data field.

16. An apparatus for wireless communication, characterized by: the apparatus is a station STA, comprising:

A memory; and

At least one processor coupled with the memory, the processor configured to:

Sending Request To Send (RTS) frames in an enhanced long-distance ELR format to acquire transmission opportunities (TXOPs);

receiving a first clear to send, CTS, frame in ELR format or non-ELR format in response to the RTS frame; and

In response to receiving the first CTS frame, data is transmitted in ELR format within a TXOP.

17. The apparatus according to claim 16, wherein: wherein the at least one processor is further configured to:

An acknowledgement in the same format as the first CTS frame is received in response to the data being transmitted.

18. The apparatus according to claim 16, wherein: wherein the at least one processor is further configured to:

Before sending the RTS frame, a CTS-to-Self frame in a non-ELR format is sent.

19. The apparatus according to claim 16, wherein: wherein the at least one processor is further configured to:

waiting a period of time in response to receiving the first CTS frame; and

Receiving a second CTS frame, wherein one of the first CTS frame and the second CTS frame adopts an ELR format and the other adopts a non-ELR format;

Wherein the data is transmitted after the period.

20. The apparatus according to claim 16, wherein: wherein the at least one processor is further configured to:

In response to not receiving any CTS frame or completely transmitting data in ELR format within an estimated transmission period, a single CF-end frame or a double CF-end frame is transmitted to terminate the TXOP.