Patent Description:
A demand currently exists for improved throughput performance in existing WLAN applications and for lower latency and high-reliability applications over WLANs. Concurrently, devices (e.g., mobile stations (STAs) and access points (APs)) have been developed with multiple radios capable of operating simultaneously on multiple channels/links that may be distributed over multiple bands, such as, for example, <NUM>, <NUM> and <NUM>. Multi-channel or multi-link operation in the same network (e.g., basic service set (BSS)) has the potential to improve the throughput, since frames from a traffic session may be transmitted on multiple channels providing increased bandwidth. This multi-channel operation also has the potential to reduce latency, since devices contend on multiple channels and utilize the first available channel. The multi-channel operation additionally has the potential to increase reliability, since frames may be duplicated over multiple channels. This multi-channel operation further has the potential to enable flexible channel/link switching without negotiation overhead. Multi-channel/multiband operation represents a paradigm shift, moving from the BSS operating on a single channel, to the BSS operating over multiple channels, in which STAs may dynamically choose to operate on a subset of channels ranging from a single channel to multiple channels.

In some forms of multi-channel operation, with respect to a pair of channels, it may be beneficial for the participating devices to have the capability to perform reception on one channel while simultaneously transmitting on the other channel (simultaneous transmit-receive (STR) capability). The STR capability on a pair of channels may be determined by several factors of radio design and BSS operation including, for example, channels of operation, bandwidth of each channel, transmit power limit, antenna distribution between the channels, etc. Therefore, a multi-radio device may lack STR capability for particular channel combinations. If the AP itself lacks STR capability, the multi-channel operation may be restricted, leading to negligible gain over legacy single-channel operation. Typically, AP devices are many-antenna systems and the AP establishes the channels of operation in the BSS. Therefore, the AP may select the channels of operation such that the AP has STR capability on every pair of channels in its BSS. In contrast, a STA might lack STR capability for a particular set of operating channels due to a smaller form factor compared to the AP. STAs that lack STR capability are referred to as non-STR STAs.

With medium access being independent on each channel, using random contention-based mechanisms, an AP may obtain medium access on each channel in an asynchronous manner. Consequently, if simultaneous downlink transmissions that begin at different times are provided to the same non-STR STA, an immediate acknowledgement response in the uplink on a first channel may overlap and ongoing downlink data transmission on a second channel. The term "overlap" refers to overlap in the time domain unless explicitly stated otherwise. Such overlap would lead to reception failure of downlink data at the non-STR STA.

From<NPL> shows a MLD that supports multiple links can announce whether it can support transmission on one link concurrent with reception on the other link for each pair of links. The <NUM> links are on different channels.

<NPL> discusses the case when a MLD has STR constrain on two links. In this case the PPDUs transmitted on the two links need to do time synchronization to avoid simultaneous transmit and receive on different links; Here the sync requirements of Trigger/TB PPDU procedure is discussed.

In <NPL> methods are proposed which can prevent non-AP MLD from experiencing constraint-related issues on the non-AP MLD side. In terms of AP MLD the end frames can be aligned in case of transmitting frames to the same non-AP MLD with constraints on multiple links. Furthermore a concept of primary link on non-AP MLD side is proposed.

<NPL> discusses a synchronization requirement of PPDU transmissions. To avoid that a STA transmit and receive frames on multi-link simultaneously, it may synchronize the ending times of the PPDU transmissions on multi-link. If the ending times of the PPDU transmissions on multi-link are synchronized, the starting times of the following PPDU transmissions are also synchronized. Therefore, a synchronization requirement of the PPDU transmissions is discussed.

Embodiments of the invention are defined in the appended claims.

Hereinafter, embodiments of the present disclosure are described in detail with reference to the accompanying drawings. It should be noted that the same elements will be designated by the same reference numerals although they are shown in different drawings. In the following description, specific details such as detailed configurations and components are merely provided to assist with the overall understanding of the embodiments of the present disclosure. Therefore, it should be apparent to those skilled in the art that various changes and modifications of the embodiments described herein may be made without departing from the scope of the present disclosure. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness. The terms described below are terms defined in consideration of the functions in the present disclosure, and may be different according to users, intentions of the users, or customs. Therefore, the definitions of the terms should be determined based on the contents throughout this specification.

In the present disclosure, it should be understood that the terms "include" or "have" indicate the existence of a feature, a number, a step, an operation, a structural element, parts, or a combination thereof, and do not exclude the existence or probability of the addition of one or more other features, numerals, steps, operations, structural elements, parts, or combinations thereof.

The electronic device adapted to one embodiment may be one of various types of electronic devices. The electronic devices may include, for example, a portable communication device (e.g., a smart phone), a computer, a portable multimedia device, a portable medical device, a camera, a wearable device, or a home appliance. According to one example of the disclosure, an electronic device is not limited to those described above.

The terms used in the present disclosure are not intended to limit the present disclosure but are intended to include various changes, equivalents, or replacements for a corresponding embodiment. With regard to the descriptions of the accompanying drawings, similar reference numerals may be used to refer to similar or related elements. A singular form of a noun corresponding to an item may include one or more of the things, unless the relevant context clearly indicates otherwise. As used herein, terms such as "<NUM>st," "2nd," "first," and "second" may be used to distinguish a corresponding component from another component, but are not intended to limit the components in other aspects (e.g., importance or order). It is intended that if an element (e.g., a first element) is referred to, with or without the term "operatively" or "communicatively", as "coupled with," "coupled to," "connected with," or "connected to" another element (e.g., a second element), it indicates that the element may be coupled with the other element directly (e.g., wired), wirelessly, or via a third element.

As used herein, the term "module" may include a unit implemented in hardware, software, or firmware, and may interchangeably be used with other terms, such as, for example, "logic," "logic block," "part," and "circuitry. " A module may be a single integral component, or a minimum unit or part thereof, adapted to perform one or more functions. For example, according to one embodiment, a module may be implemented in a form of an application-specific integrated circuit (ASIC).

An AP may establish a BSS operation over multiple channels. These channels may be disposed on different bands, although a subset of the channels may be disposed on the same band. Examples of a multi-channel BSS include a <NUM> operation in a <NUM> band, an <NUM> operation in a <NUM> band, and a <NUM> operation in a <NUM> band. Due to a diversity in channel conditions across the channels, a data rate used by a device may be different on different channels. The AP advertises the multi-channel operation in broadcast frames including, for example, beacons, probe responses, etc. STAs joining the BSS may indicate the channels they want to operate on during association and/or dynamically in the form of an operating mode change indication after association. For example, a STA may temporarily switch to single channel operation for power saving when it has no backlogged traffic or for coexistence with other technologies (e.g., Bluetooth). Herein, multi-channel operation is described over two channels, but is not limited thereto.

Medium access in each channel does not require synchronization between channels. <FIG> is a diagram illustrating multichannel medium access by a device operating on channels A and B. A channel may be considered to be in a busy channel state upon detecting an energy above an energy detection threshold. A first busy channel state 102A is shown on channel A, and a second busy channel state 102B is shown on channel B. A data transmission on a channel begins when a value of a backoff counter reaches zero. A first backoff counter 104A is shown on channel A, and a second backoff counter 104B is shown on channel B.

A single physical protocol layer data unit (PPDU) transmission consists of a physical (PHY) layer preamble and multiple media access control (MAC) layer data units (MPDUs). A first PPDU 106A is shown on channel A and includes a first PHY preamble 108A and a first set of MPDUs 110A-<NUM> to 110A-<NUM>. A second PPDU 106B is shown on channel B and includes a second PHY preamble 108B and a second set of MPDUs 110B-<NUM> to 110B-<NUM>. A corresponding immediate Block Ack includes a bitmap in which each bit acknowledges the successful reception of a corresponding MPDU. A first Block Ack 112A is shown on channel A in response to the reception of the first PPDU 106A, and a second Block Ack 112B is shown on channel B in response to the reception of the second PPDU 106B. <FIG> illustrates the asynchronous nature of the medium access, in which the first Block Ack 112A on channel A occurs simultaneously with the second PPDU 106B on channel B.

To realize the full potential of multi-channel operation, participating devices would ideally be capable of simultaneous bi-directional communication on the multiple channels. With such capability, uplink and downlink communication can occur simultaneously between the AP and the STA in an asynchronous manner. However, a multi-radio device may lack such a capability due to in-device power leakage caused by insufficient frequency separation of the operating channels.

Accordingly, STAs in multi-channel BSS may be classified as a simultaneous transmit-receive (STR) STA or a non-STR STA. The STR STA is capable of STR, simultaneous transmit-transmit (STT), and simultaneous receive-receive (SRR). The non-STR STA is not capable of STR, but is capable of STT and SRR. Accordingly, the non-STR STA cannot detect a PHY preamble or decode a PHY header on channel A when transmitting on channel B.

Referring now to <FIG>, a diagram illustrates simultaneous downlink transmission to a non-STR STA. An AP having STR capability can receive a Block Ack transmission on channel A even while transmitting to a non-STR STA on channel B.

Reference numerals 202A, 202B, 204A, 204B, 206A, 206B, 208A, 208B, 210A-<NUM> to 210A-<NUM>, 210B-<NUM> to 210B-<NUM>, 212A, and 212B of <FIG> respectively correspond to reference numerals 102A, 102B, 104A, 104B, 106A, 106B, 108A, 108B, 110A-<NUM> to 110A-<NUM>, 110B-<NUM> to 110B-<NUM>, 112A, and 112B of <FIG>, which are described above. The transmission of a Block Ack 212A by the non-STR STA on channel A interferes with the downlink data transmission of a PPDU 206B to the same non-STR STA on channel B. As shown in <FIG>, only MPDUs being received on channel B that overlap with the Block Ack transmission on Channel A are lost. Specifically, MPDUs 210B-<NUM> and 210B-<NUM> are lost due to the interference.

<FIG> is a diagram illustrating simultaneous downlink transmission to a non-STR STA. Similar to <FIG>, <FIG> illustrates the transmission of a Block Ack 212A by a non-STR STA on channel A interfering with a downlink data transmission of a PPDU 206B to the same non-STR STA on channel B. However, as shown in <FIG>, the transmission of the Block Ack 212A on channel A impacts the signal-to-noise-interference ratio on channel B to an extent that reception goes out of sync, leading to reception failure for all MPDUs from the start of the Block Ack transmission to the end of the data transmission. Specifically, MPDUs 210B-<NUM>, 210B-<NUM>, and 210B-<NUM> are lost due to interference.

<FIG> is a diagram illustrating simultaneous downlink transmission to a non-STR STA. Specifically, <FIG> illustrates the transmission of a Block Ack by the non-STR STA on channel A overlapping with the start of a downlink transmission to the non-STR STA on channel B. Specifically, a Block Ack 212A overlaps with a PHY preamble 208B and MPDU 210B-<NUM> of the PPDU 206B. Since the non-STR STA fails to decode the PHY preamble 208B, the non-STR STA fails to receive all of the MPDUs 210B-<NUM> to 210B-<NUM> on channel B, and does not respond with a Block Ack on channel B.

Accordingly, as shown in <FIG>, downlink performance degradation may occur if an AP attempts transmission on a first channel without considering the ongoing frame exchange on a second channel.

As described above, depending on the reception capability of the non-STR STA for the channels of operation, the MPDUs on another channel may not be received beyond the Block Ack transmission phase. Such reception failure would not occur if the AP aligned the endings of the data transmissions on both channels. Consequently, the Block Acks are transmitted on both channels at the same time.

<FIG> is a diagram illustrating simultaneous downlink transmission to a non-STR STA with ending alignment, according to an embodiment. Reference numerals 302A, 302B, 304A, 304B, 306A, 306B, 308A, 308B, 310A-<NUM> to 310A-<NUM>, 310B-<NUM> to 310B-<NUM>, 312A, and 312B of <FIG> respectively correspond to reference numerals 102A, 102B, 104A, 104B, 106A, 106B, 108A, 108B, 110A-<NUM> to 110A-<NUM>, 110B-<NUM> to 110B-<NUM>, 112A, and 112B of <FIG>, which are described above.

For each pair of channels, the non-STR STA indicates to the AP whether the AP should always align or may adaptively align endings of simultaneous downlink data transmissions to this non-STR STA. The non-STR STA may provide this information during the initial association with AP and/or in a dynamic manner after association. For example, the non-STR STA may indicate its updated requirement whenever the operating parameters of a channel are updated by the AP, since the operating parameters determine the STR capability and reception capability at the non-STR STA on corresponding pairs of channels.

If the non-STR STA indicates that the AP should always align the endings of the downlink transmission, then the AP will always align simultaneous downlink transmissions to the same non-STR STA. For example, as shown in <FIG>, the AP starts transmission of a PPDU 306B to the non-STR STA on channel B immediately after a backoff counter 304B reaches zero, and aligns the end of the PPDU 306B on channel B with the end of an ongoing data transmission of a PPDU 306A to the same non-STR STA on channel A. In order to achieve this alignment, the AP may employ fragmentation and padding mechanisms known by those skilled in the art.

In the invention the non-STR STA indicates that the AP may adaptively align the downlink transmissions, the AP adaptively aligns the ending of the data transmission based on the potential data reception failure at the non-STR STA if alignment is not performed (e.g. the potential failures shown in <FIG>). Depending on the interference conditions on channel B and the rate adaptation mechanism employed by the AP, the AP determines the modulation and coding rate for the data transmission on channel B. Accordingly, the AP uses knowledge of the start and end times of a potential Block Ack transmission by the non-STR STA on channel A to determine the number of MPDUs that would not be received by the non-STR STA if the ending of the data transmission on channel B is not aligned with that on channel A. This MPDU reception failure at the non-STR STA may occur on channel A instead of channel B if the data transmission on channel B ends earlier than that of channel A.

Therefore, using a predefined MPDU loss threshold, the AP may align the ending of the data transmission on channel B with that of channel A, if the estimated number of MPDUs that may suffer reception failure at the non-STR STA is greater than or equal to this predefined threshold. Otherwise, the AP may perform transmission on channel B without any alignment with the ongoing transmission on channel A to the same non-STR STA.

Referring back to <FIG>, the uplink Block Ack transmission 212A on channel A overlaps with the PHY preamble of data 208B on channel B, and the entire data transmission on channel B is not received at the non-STR STA. Since the AP reserves the channel A medium for both the data transmission and corresponding acknowledgement reception, the AP has precise knowledge of the start and end time of the potential Block Ack response from the non-STR STA on channel A. Additionally, the AP has knowledge of the start and end of the PHY preamble corresponding to a potential transmission on Channel B. Therefore, after the backoff counter reaches zero on channel B, if the AP determines an overlap would occur between the Block Ack from the non-STR STA on channel A and the PHY preamble to the same non-STR STA on channel B, the AP will not initiate data transmission on Channel B to the same non-STR STA, and may re-attempt transmission after the reserved medium time on channel A by the AP expires. However, since the AP does not perform transmission, the medium can be obtained by neighboring devices operating on channel B before the reserved medium time on channel A expires. The AP can also choose to transmit to other STAs instead of the same non-STR STA to avoid the issue.

<FIG> is a flowchart illustrating, as technological background, a method for receiving simultaneous downlink transmissions at a STA. The STA is a non-STR STA, as described above. At <NUM>, information is transmitted to an AP regarding whether endings of simultaneous data transmissions to the mobile station are to be aligned. The information is transmitted during an initial association between the STA and the AP and/or in a dynamic manner after the initial association. The simultaneous data transmissions are between the AP and the STA over a pair of channels.

At <NUM>, the STA begins reception of a first data transmission, from the AP, on a first channel of the pair of channels. At <NUM>, the STA begins reception of a second data transmission, from the AP, on a second channel of the pair of channels. The second data transmission overlaps at least a portion of the first data transmission. The second data transmission may begin after the first data transmission.

At <NUM>, the STA ends reception of the second data transmission upon an end of the first data transmission, when the information indicates that the endings of simultaneous downlink data transmissions are to be aligned. The second data transmission may be shortened to align its ending with that of the first data transmission.

<FIG> is a flowchart illustrating a method for transmitting simultaneous downlink transmissions at an AP, according to an embodiment. At <NUM>, information is received from a STA regarding whether endings of simultaneous data transmissions to the STA are to be aligned. The simultaneous data transmissions are between the AP and the STA over a pair of channels. The STA is a non-STR STA, as described above. The information is transmitted during an initial association between the mobile station and the AP and/or in a dynamic manner after the initial association.

At <NUM>, the AP begins transmission of a first data transmission, to the STA, on a first channel of the pair of channels. At <NUM>, the AP begins transmission of a second data transmission, to the mobile station, on a second channel of the pair of channels. The second data transmission overlaps at least a portion of the first data transmission. The second data transmission may begin after the first data transmission.

At <NUM>, a second ending of the second data transmission is aligned with a first ending of the first data transmission, when the information indicates that the endings of simultaneous data transmissions are to be aligned. At <NUM>, endings of the first and second data transmissions are adaptively aligned based on a number of packet data units (PDUs) that would not be received if endings are not aligned.

With respect to adaptive alignment, the number of PDUs of the second transmission are determined that would not be received by the STA due to interference with feedback transmitted to the AP on the first channel, should the second data transmission continue without aligning the second ending with the first ending. The number of PDUs is determined based on information at the AP regarding expected transmission times of the feedback and the second transmission. The second ending is aligned with the first ending when the number of PDUs is greater than or equal to a predefined threshold. The transmission of the second downlink data transmission is maintained beyond the first ending, when the number of PDUs is less than the predefined threshold.

<FIG> is a block diagram of an electronic device in a network environment, adapted to one embodiment. Referring to <FIG>, an electronic device <NUM> in a network environment <NUM> may communicate with an electronic device <NUM> via a first network <NUM> (e.g., a short-range wireless communication network), or an electronic device <NUM> or a server <NUM> via a second network <NUM> (e.g., a long-range wireless communication network). The electronic device <NUM> may communicate with the electronic device <NUM> via the server <NUM>. The electronic device <NUM> may include a processor <NUM>, a memory <NUM>, an input device <NUM>, a sound output device <NUM>, a display device <NUM>, an audio module <NUM>, a sensor module <NUM>, an interface <NUM>, a haptic module <NUM>, a camera module <NUM>, a power management module <NUM>, a battery <NUM>, a communication module <NUM>, a subscriber identification module (SIM) <NUM>, or an antenna module <NUM>. In one embodiment, at least one (e.g., the display device <NUM> or the camera module <NUM>) of the components may be omitted from the electronic device <NUM>, or one or more other components may be added to the electronic device <NUM>. In one embodiment, some of the components may be implemented as a single integrated circuit (IC). For example, the sensor module <NUM> (e.g., a fingerprint sensor, an iris sensor, or an illuminance sensor) may be embedded in the display device <NUM> (e.g., a display).

The processor <NUM> may execute, for example, software (e.g., a program <NUM>) to control at least one other component (e.g., a hardware or a software component) of the electronic device <NUM> coupled with the processor <NUM>, and may perform various data processing or computations. As at least part of the data processing or computations, the processor <NUM> may load a command or data received from another component (e.g., the sensor module <NUM> or the communication module <NUM>) in volatile memory <NUM>, process the command or the data stored in the volatile memory <NUM>, and store resulting data in non-volatile memory <NUM>. Additionally or alternatively, the auxiliary processor <NUM> may be adapted to consume less power than the main processor <NUM>, or execute a particular function. The auxiliary processor <NUM> may be implemented as being separate from, or a part of, the main processor <NUM>.

The auxiliary processor <NUM> may control at least some of the functions or states related to at least one component (e.g., the display device <NUM>, the sensor module <NUM>, or the communication module <NUM>) among the components of the electronic device <NUM>, instead of the main processor <NUM> while the main processor <NUM> is in an inactive (e.g., sleep) state, or together with the main processor <NUM> while the main processor <NUM> is in an active state (e.g., executing an application). According to one embodiment, the auxiliary processor <NUM> (e.g., an image signal processor or a communication processor) may be implemented as part of another component (e.g., the camera module <NUM> or the communication module <NUM>) functionally related to the auxiliary processor <NUM>.

The communication module <NUM> may include one or more communication processors that are operable independently from the processor <NUM> (e.g., the AP) and supports a direct (e.g., wired) communication or a wireless communication. According to one embodiment, the communication module <NUM> may include a wireless communication module <NUM> (e.g., a cellular communication module, a short-range wireless communication module, or a global navigation satellite system (GNSS) communication module) or a wired communication module <NUM> (e.g., a local area network (LAN) communication module or a power line communication (PLC) module). A corresponding one of these communication modules may communicate with the external electronic device via the first network <NUM> (e.g., a short-range communication network, such as Bluetooth™, wireless-fidelity (Wi-Fi) direct, or a standard of the Infrared Data Association (IrDA)) or the second network <NUM> (e.g., a long-range communication network, such as a cellular network, the Internet, or a computer network (e.g., LAN or wide area network (WAN)). These various types of communication modules may be implemented as a single component (e.g., a single IC), or may be implemented as multiple components (e.g., multiple ICs) that are separate from each other. According to an embodiment of the present disclosure, one or more wireless communication modules <NUM> may communicate with both a cellular network and a LAN over the second network <NUM>.

According to one embodiment, commands or data may be transmitted or received between the electronic device <NUM> and the external electronic device <NUM> via the server <NUM> coupled with the second network <NUM>.

Claim 1:
A method for receiving simultaneous downlink transmissions at a mobile station, the method comprising:
transmitting (<NUM>), to an access point, AP, information indicating that endings of simultaneous data transmissions to the mobile station are to be adaptively aligned based on a data unit loss threshold, wherein the simultaneous data transmissions are between the AP and the mobile station over a pair of channels;
beginning reception of a first data transmission (<NUM>), from the AP, on a first channel of the pair of channels;
beginning reception of a second data transmission (<NUM>), from the AP, on a second channel of the pair of channels, wherein the second data transmission overlaps at least a portion of the first data transmission; and
ending reception (<NUM>) of the second data transmission upon an end of the first data transmission when endings are aligned based on the data unit loss threshold.