COMMUNICATION DEVICE AND COMMUNICATION METHOD ACCORDING TO MULTILINK TRAFFIC INDICATION MAP

Abstract

To reduce the overhead required for signaling additional information about buffered BUs in WLAN networks that contain MLDs.SOLUTION: A station (STA) is an STA of multiple stations (STAs) belonging to a non-AP Multi-Link Device (MLD), each of the STAs operating in a corresponding link of the non-AP MLD. The STA includes: a receiving unit which receives a frame comprising a traffic indication map (TIM) element and starting AID information, the TIM element including a partial virtual bitmap (PVM) indicating the presence of one or more buffered units (BUs) for the non-AP MLD, the starting AID information indicating the smallest AID for which additional information relating to one or more BUs is present in the frame; and circuitry which processes receiving the frame.SELECTED DRAWING: Figure 18

Description

[Technical Field]

[0001] The present embodiments relate to communication devices, and more particularly to methods and devices supporting multi-link traffic indication maps. [Background technology]

[0002] Today, communication devices are expected to perform the same functions as wired computing devices, but wirelessly. For example, users expect to be able to seamlessly watch high-definition movies streamed to their wireless communication devices. This creates challenges for the communication devices and for the access points to which they connect wirelessly.

[0003] The Institute of Electrical and Electronics Engineers (IEEE) 802.11 Group recently launched an 802.11 Task Group (TG) to address these challenges. Multilink operation in the 2.4 GHz, 5 GHz, and 6 GHz frequency bands has been identified as a candidate technology for such communications. Multichannel aggregation across multiple links is a natural way to increase communication data throughput several times. Summary of the Invention [Problem to be solved by the invention]

[0004] In multilink operation between an access point (AP) multilink device (MLD) and a non-AP MLD, a traffic indication map (TIM) element is conveyed, e.g., in a beacon frame or a TIM frame, to indicate buffered traffic (BU) for associated non-AP STAs operating in power save (PS) mode. Unlike single-link operation, in multilink operation, the BU indication in the TIM element alone does not provide additional information about the BU, such as a recommended link for acquiring the BU or a TID associated with the BU. While other methods can be used to signal additional information about buffered BUs, such as link mapping, link set indication with link recommendations, or traffic identifiers (TIDs), an additional bitmap is required for each bit set to 1 in the TIM element in order for the non-AP MLD to properly locate itself in the link / TID information set, regardless of the method used, as described below.

[0005] Therefore, what is needed is a communication apparatus and method that supports a multilink traffic indication map to address the above-mentioned problems and reduce the overhead required to signal additional information about buffered BUs in a WLAN network that includes an MLD. Furthermore, other desirable features and characteristics will become apparent from the following detailed description and appended claims, taken in conjunction with the accompanying drawings and the Background section of this disclosure. [Means for solving the problem]

[0006] Non-limiting exemplary embodiments facilitate providing a communications apparatus and method that supports a multi-link traffic indication map.

[0007] In a first embodiment, the present disclosure provides an AP among a plurality of access points (APs) belonging to an AP multi-link device (MLD), each of the plurality of APs operating on a corresponding link of the AP MLD, the AP comprising the following components: a circuit that, in operation, generates a frame including a traffic indication map (TIM) element and a presence bitmap, wherein the TIM element includes a partial virtual bitmap (PVM) indicating the presence of one or more buffered units for one of non-AP STAs or non-AP MLDs associated with the AP or AP MLD, and the presence bitmap indicates whether additional information related to one or more BUs is present in a frame intended for one of the non-AP STAs or non-AP MLDs; and a transmitter that, in operation, transmits the frame on the link.

[0008] In a second embodiment, the present disclosure provides a station (STA), one of a plurality of stations (STAs) belonging to a non-access point (non-AP) multilink device (MLD) associated with an AP MLD, each of the plurality of STAs operating on a corresponding link of the non-AP MLD, the STA comprising the following components: a receiver that, in operation, receives frames on the link, the frames including a traffic indication map (TIM) element and a presence bitmap, the TIM element including a partial virtual bitmap (PVM) indicating the presence of one or more buffered units for the non-AP MLD, and the presence bitmap indicating whether additional information related to one or more BUs is present in the frame intended for the non-AP MLD; and a circuit that, in operation, processes the frames.

[0009] In a third embodiment, the present disclosure provides a communication method, the method including: generating a frame including a traffic indication map (TIM) element and a presence bitmap, wherein the TIM element includes a partial virtual bitmap (PVM) indicating the presence of one or more buffered units for one of a non-AP STA or a non-AP MLD associated with an AP or an AP MLD, and the presence bitmap indicates whether additional information related to one or more BUs is present in the frame intended for one of the non-AP STA or the non-AP MLD; and transmitting the frame on a link.

[0010] Additional benefits and advantages of the disclosed embodiments will become apparent from the specification and drawings. These benefits and / or advantages may be obtained individually by the various embodiments and features of the specification and drawings, and it is not necessary for all of the embodiments and features to be provided in order to obtain one or more of such benefits and / or advantages. [Brief explanation of the drawings]

[0011] The accompanying drawings, which together with the following detailed description are incorporated in and constitute a part of this specification, illustrate various embodiments and serve to explain various principles and advantages according to the present embodiments. Throughout the different drawings, like reference numerals indicate identical or functionally similar elements. [Figure 1] 1 shows a TIM element and its Bitmap Control field. [Figure 2] 1 shows a schematic diagram illustrating communication between AP MLD and non-AP MLD for multi-link power management and traffic direction. [Figure 3] 1 shows a TIM bitmap and a set of link mapping bitmaps (LMBs). [Figure 4]1 shows the TIM bitmap and link recommendation (LR) elements. [Figure 5] 5 shows a TIM bitmap 500 in a TIM element, a multi-link (ML)-TIM element, and an LR element. [Figure 6] 1 shows a TIM bitmap and a traffic identifier (TID) bitmap. [Figure 7] The TIM bitmap and TID indication are shown. [Figure 8] 8 shows a schematic diagram illustrating an exemplary configuration of a communication device 800 according to the present disclosure. [Figure 9] 1 shows a flowchart illustrating a communication method corresponding to a multi-link traffic map according to various embodiments of the present disclosure. [Figure 10] 1 shows an exemplary beacon / TIM frame. [Figure 11] 1 shows exemplary associated identifier (AID) assignments and three exemplary TIM bitmaps transmitted by AP-MLD on three links, respectively. [Figure 12] 1 shows an exemplary TIM bitmap, an exemplary LMB presence bitmap, and an exemplary LMB set in a TIM frame / beacon frame. [Figure 13] 1 illustrates an exemplary TIM bitmap, an exemplary LR presence bitmap, and an exemplary LR bitmap set in a TIM frame / beacon frame. [Figure 14] 1 illustrates an exemplary TIM bitmap, an exemplary linkset presence bitmap, an exemplary linkset bitmap set, and an exemplary LR bitmap set in a TIM frame / beacon frame. [Figure 15] 1 illustrates an exemplary TIM bitmap, an exemplary TID information presence bitmap, and an exemplary TID information bitmap set in a TIM frame / beacon frame. [Figure 16] 1 illustrates an exemplary TIM bitmap, an exemplary AC information presence bitmap, and an exemplary AC information bitmap set in a TIM frame / beacon frame. [Figure 17] 1 shows an exemplary AID assignment and three exemplary TIM bitmaps transmitted from an AP MLD on three links, respectively. [Figure 18] 1 shows an exemplary beacon / TIM frame. [Figure 19] 1 illustrates an exemplary TIM bitmap and an exemplary LMB set in a beacon / TIM frame. [Figure 20] 1 illustrates another exemplary beacon / TIM frame. [Figure 21] 1 illustrates an exemplary TIM bitmap, an exemplary TID information presence bitmap, and an exemplary TID information bitmap set in a beacon frame / TIM frame. [Figure 22] 10 illustrates an exemplary TIM bitmap transmitted on a link from an AP MLD, and exemplary formats of an AC information present bitmap and AC information bitmap set. [Figure 23] 23 shows an exemplary format of the TIM bitmap, TID information present bitmap 2304, and TID information bitmap set in a beacon / TIM frame. [Figure 24] 1 illustrates an exemplary format of a Multi-link TIM element. [Figure 25] 1 illustrates an exemplary TIM bitmap, an exemplary multilink TIM bitmap, an exemplary AC information presence bitmap, and an exemplary AC information bitmap set in a beacon / TIM frame. [Figure 26] 1 illustrates an exemplary format of a Multi-link TIM element containing a Multi-link TIM bitmap. [Figure 27]1 illustrates an exemplary configuration of a communication device and three communication devices belonging to the communication device, where the communication device is implemented as an AP MLD, and each of the belonging communication devices may be implemented as an AP configured to support a multilink traffic indication map according to the present disclosure. [Figure 28] 1 illustrates an exemplary configuration of a communication device and three communication units belonging to the communication device, where the communication device is implemented as a non-AP MLD and each of the communication units can be implemented as a STA configured to support a multilink traffic indication map according to the present disclosure.

[0012] Those skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some elements in illustrations, block diagrams, or flowcharts may be exaggerated relative to other elements to facilitate an accurate understanding of the present embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0013] The following detailed description is merely exemplary and is not intended to limit the embodiments or the application and uses of the embodiments. Moreover, there is no intention to be bound by the theories presented in the preceding Background or Detailed Description sections. Moreover, other desirable features and characteristics will become apparent from the following detailed description and the appended claims, taken in conjunction with the accompanying drawings and the background of this disclosure.

[0014] In the context of IEEE 802.11 (Wi-Fi) technology, a station (also synonymously referred to as a STA) is a communication device capable of using the 802.11 protocol. Based on the definition in IEEE 802.11-2020, a STA can be any device that includes an IEEE 802.11-compliant medium access control (MAC) and physical layer (PHY) interface to the wireless medium (WM).

[0015] For example, a STA may be a laptop, desktop personal computer (PC), personal digital assistant (PDA), access point (AP), or Wi-Fi phone in a wireless local area network (WLAN) environment. A STA may be fixed or mobile. In a WLAN environment, the terms "STA," "wireless client," "user," "user device," and "node" are often used synonymously.

[0016] Similarly, an AP (also known synonymously as a wireless access point (WAP) in the context of IEEE 802.11 (Wi-Fi) technology) is a communications device that allows STAs in a WLAN to connect to a wired network. APs are typically standalone devices that connect to a router (through the wired network), but can also be built into or used in a router.

[0017] As mentioned above, a STA in a WLAN may function as an AP in some cases, and vice versa. This is because a communication device in the context of IEEE 802.11 (Wi-Fi) technology may include both STA and AP hardware components. In this manner, the communication device may switch between STA mode and AP mode based on the conditions and / or requirements of the actual WLAN.

[0018] In various embodiments of the present disclosure, a multi-link device (MLD) refers to a device that operates on two or more frequency bands or links (2.4 GHz, 5 GHz, or 6 GHz). An MLD can include two or more communication devices corresponding to the two or more links, with each communication device operating on a specific frequency band or link. For simplicity, each link of an MLD shown in this disclosure is associated with one of multiple communication devices belonging to that MLD, which operates on a specific frequency band (2.4 GHz, 5 GHz, or 6 GHz) and is primarily configured to transmit / receive signals to / from another communication device (operating on that specific frequency band) that does not belong to that MLD.

[0019] In various embodiments of the present disclosure, unless otherwise specified, a non-MLD STA, 11n STA, 11ac STA, or 11ax STA refers to a legacy (HE / VHT / HT) STA or an EHT STA that does not belong to an MLD. Similarly, a non-MLD AP refers to an EHT AP that does not belong to an MLD.

[0020] In various embodiments of the present disclosure, a partial virtual bitmap (PVM) field refers to a bitmap of Traffic Indication Map (TIM) elements carried in frames transmitted on a link by an AP or AP MLD, and the terms "PVM" or "partial virtual bitmap" are used as synonyms for TIM bitmap.

[0021] A Traffic Indication Map (TIM) element is carried in a beacon frame to indicate buffered traffic (BU) for non-AP STAs operating in power save (PS) mode. Figure 1 shows the TIM element and a Bitmap Control field of the TIM element 100. The TIM element 100 includes an Element Identifier (ID) field, a Length field, a Delivery TIM (DTIM) Count field, a DTIM Period field, a Bitmap Control field 102, and a Partial Virtual Bitmap (PVB) field. The Bitmap Control field 102 includes a Traffic Indicator field and a Bitmap Offset field. The Length field is set to (N1 + N2) + 4, where N1 is the largest even number such that bits numbered 1 through (N1 × 8) - 1 in the Traffic Indication Virtual Bitmap are all 0, and N2 is the smallest number such that bits numbered (N2 + 1) × 8 through 2007 in the Traffic Indication Virtual Bitmap are all 0. N1 and N2 are used to signal the actual range of the TIM bitmap conveyed in the PVB field when the TIM bits at both ends of the AID range are all set to 0. The PVB field is set to 1 for an AID to indicate that there are buffered BUs for that AID. The Traffic Indicator is set to 1 in TIM elements with the DTIM Count field set to 0 when one or more group-addressed Media Access Control (MAC) Service Data Units (MSDUs) / MAC Management Protocol Data Units (MMPDUs) are buffered at the AP.When one or more group-addressed MSDUs / MMPDUs are buffered at the AP, the DTIM Count field is set to 1 in TIM elements that are set to 0. The Bitmap Offset field contains the value N1 / 2.

[0022] In multilink power management, each STA of a non-AP MLD operating on an active link maintains its own power management mode and power state. Each STA of a non-AP MLD can independently change its power management mode or power state. Figure 2 shows a schematic diagram 200 illustrating communication between an AP MLD 202 and a non-AP MLD 204 for multilink power management and traffic direction. If the STAs (e.g., STA1, STA2) of the non-AP MLD 204 operating on an active link are operating in active mode or power save mode awake state (e.g., the value of the PM (Power Management Mode) field is set to 0), frame exchange is possible on that link, but if the AP MLD 202 has buffered traffic (BU) for the associated non-AP MLD 204's affiliated STAs (e.g., STA1, STA2) (the affiliated STAs are operating in power save mode doze state (e.g., the value of the PM (Power Management Mode) field is set to 1)), the corresponding affiliated AP (e.g., AP1, AP2) on the AP MLD 202 side uses the TIM element carried in the beacon frame to indicate the buffered traffic for the non-AP MLD 204.

[0023] TID-Link Mapping is a new mechanism introduced in 802.11be that allows AP MLD and non-AP MLDs that have performed multilink setup to determine how TIDs are mapped to established links in the downlink (DL) and uplink (UL). By default, all TIDs are mapped to all established links in both the UL and DL. If a TID is mapped to a link in a particular direction (DL / UL), transmission of frames belonging to that TID is allowed in that direction.

[0024] An established link is defined as valid if at least one TID is mapped to it, and invalid if no TID is mapped to it. At any point in time, a TID is always mapped to at least one established link, unless admission control is used. By default, all TIDs are mapped to all established links, and therefore all established links are valid.

[0025] If a TID is mapped to a set of valid links for a non-AP MLD in the UL, the non-AP MLD can use any link in this set of valid links to transmit frames carrying MSDUs or A-MSDUs (aggregation MSDUs) with that TID. If a TID is mapped to a set of valid links for a non-AP MLD in the DL, the non-AP MLD can obtain buffered BUs corresponding to that TID on any link in this set of valid links, while the AP MLD can transmit frames carrying MSDUs or A-MSDUs with that TID using any link in this set of valid links, subject to existing restrictions on frame transmission that apply to those valid links.

[0026] Conventionally, the TIM element is used as is. For non-AP MLDs, a TIM bit is assigned for each non-AP MLD, regardless of the number of established links; i.e., one AID is assigned to the non-AP MLD across all links. The TIM bit for a non-AP STA / MLD is set to 0 if the AP MLD has no buffered frames to send to the non-AP STA / MLD, and is set to 1 if the AP MLD has one or more buffered frames to send to the non-AP STA / MLD on any of the links used. According to the IEEE 802.11-2020 specification, any value within the range of 1 to 2007 can be used as the AID of an associated STA; however, in various examples used in this disclosure, the AP MLD assigns AIDs to associated non-AP STAs and non-AP MLDs within the AID range of 1 to 255.

[0027] In addition to the traditional TIM element, another element carrying, for example, the LMB, is defined to indicate the buffered data to link mapping for each non-AP MLD whose TIM bit is set to 1.

[0028] FIG. 3 shows a TIM bitmap 300 and a set of LMBs 302 in a TIM element. Each bit in the TIM bitmap, except for AID 0, corresponds to an AID of a non-AP STA / MLD. The TIM bits corresponding to AIDs 12, 28, 35, 57, and 77 are set to 1, indicating that the AP MLD has one or more buffered frames to transmit to the corresponding STA / MLD associated with the AID. For each bit set to 1 in the TIM bitmap 300, there is one LMB. In this case, the non-AP MLD calculates the location of its LMB in the LMB set 302 based on the order of the bits set to 1 in the TIM bitmap 300. Traditionally, an LMB is required for legacy STAs so that the non-AP MLD can correctly find its LMB because legacy STAs cannot be identified based on the TIM bitmap 300. In one example, the number of bits in one LMB corresponds to the number of valid links of the non-AP MLD.

[0029] When a non-AP MLD sees that the TIM bit corresponding to its AID is set to 1 in the TIM element, it further checks the LMB corresponding to that AID to identify the specific link(s) to which the buffered traffic is mapped. For example, a non-AP MLD with AID 28 sees that its TIM bit is set to 1, so that the AP MLD has buffered traffic on one of its enabled links. The non-AP MLD then sees that its LMB is second in order (its second bit set to 1 in the TIM bitmap) and checks the second LMB in the set of LMBs 302. The non-AP MLD then sees that the second and third bits of its LMB are set to 1, indicating that the AP MLD has buffered traffic for the non-AP MLD on link 2 and link 3.

[0030] In another conventional example, AIDs are assigned to non-AP MLDs, and the TIM element indicates the BU status of each non-AP MLD. In the default TID-link mapping, a TID is mapped to all valid links. When the bit in the TIM element corresponding to the AID of a non-AP MLD is set to 1, the non-AP MLD can obtain buffered data through any of the valid links, but the AP MLD can indicate a preferred link(s) using the LR element. In the LR element, a bitmap is assigned to the non-AP MLD, and each bit in the bitmap corresponds to a link and indicates whether the link is recommended for use.

[0031] 4 shows a TIM bitmap 400 and an LR element 402. In TIM bitmap 400, the TIM bits (bit 1 and bit 3) associated with the AID of non-AP MLD 1 and the AID of non-AP MLD 3 are set to 1, indicating that the AP MLD has one or more buffered frames to transmit to non-AP MLD 1 and non-AP MLD 3. LR element 402 includes a bitmap for each bit set to 1 in TIM bitmap 400, where bitmap 1 and bitmap 3 indicate recommended links for non-AP MLD 1 and non-AP MLD 3, respectively. In one example, the number of bits in the LR bitmap corresponds to the number of valid links for the non-AP MLD. Bitmap 1 has the values ​​"1," "0," and "0," indicating that the first link is recommended for non-AP MLD 1 to retrieve buffered frames from the AP MLD. Bitmap 3 has values ​​"0", "0", and "1", indicating that the third link is recommended for non-AP MLD 3 to retrieve buffered frames from the AP MLD.

[0032] In addition to the default TID-link mapping, two or more links can be grouped into one link set, and different TIDs can be mapped to different link sets. The new Multi-Link (ML) TIM element can be used to indicate the BU status of different link sets. A bitmap in the ML TIM element is assigned to non-AP MLDs. Each bit in the bitmap is mapped to a link set to indicate the BU status, e.g., set to 1 if one or more BUs exist for the link set, or set to 0 if no BUs exist. The LR element can also be used to indicate the recommended link within a link set.

[0033] 5 shows a TIM bitmap 500, an ML-TIM element 502, and an LR element 504. TIDs 0-3 are mapped to a first link set consisting of Link 1 and Link 2, while TIDs 4-7 are mapped to a second link set consisting of Link 3. The TIM bits (bit 1 and bit 2) corresponding to the AIDs of non-AP MLD 1 and non-AP MLD 2 are set to 1, indicating that the AP MLD has one or more buffered frames to transmit to non-AP MLD 1 and non-AP MLD 2. The ML-TIM element 502 includes a bitmap for each bit set to 1 in the TIM element, where Bitmap 1 and Bitmap 2 indicate the BU state of different link sets for non-AP MLD 1 and non-AP MLD 2, respectively. The number of bits in the ML-TIM bitmap 502 corresponds to the number of link sets. Bitmap 1 has values ​​"1" and "0", indicating that the first link set has BU for non-AP MLD 1, and bitmap 2 has values ​​"0" and "1", indicating that the second link set has BU for non-AP MLD 2.

[0034] The LR element 504 further includes bitmaps indicating the recommended links in the linkset, where Bitmap 1 has values ​​"0", "1", indicating that the second link in Linkset 1 (i.e., Link 2 for Non-AP MLD 1) is the recommended link. Bitmap 2 indicates a second linkset for Non-AP MLD 2, and because the second linkset contains only one link (Link 3), Link 3 is recommended for Non-AP MLD 2 and no separate LR element is required.

[0035] In yet another conventional example, non-AP MLDs are assigned AIDs, and the TIM element indicates the BU status of each non-AP MLD. The TID bitmap (8 bits per TID) for each bit set to 1 for a non-AP MLD in the TIM element indicates the TIDs for which the AP MLD has one or more BUs for the non-AP MLD. Each bit in the TID bitmap represents a TID, starting with TID 0, and a bit set to 1 indicates that buffered frames belonging to the corresponding TID are present in the AP MLD. The STA uses the TID-link mapping to determine which link to wake up to retrieve buffered MPDUs (MAC Protocol Data Units). This example assumes that different TIDs are mapped to different links.

[0036] FIG. 6 shows a TIM bitmap 600 and a TID bitmap 602 in a TIM element. In TIM bitmap 600, the TIM bits corresponding to one non-AP STA assigned AID 27 and five non-AP MLDs assigned AIDs 12, 28, 35, 57, and 77 are set to 1, indicating that the AP MLD has one or more buffered frames to transmit to the corresponding STA and MLD, respectively. For each non-AP MLD's TIM bit set to 1 in the TIM element, there is an 8-bit TID. In this case, TID bitmap 602 includes five 8-bit TIDs for each of the five non-AP MLDs for which the AP MLD has one or more buffered frames to transmit. The 8-bit TIDs are used by each non-AP MLD to determine which link(s) to wake up to retrieve buffered MPDUs from the AP MLD. However, in this example, it is not clear whether a TID indication is also required for legacy non-AP STAs with AID 27. However, without this TID indication, non-AP MLDs with AIDs greater than 27 would not be able to identify their correct TID indication.

[0037] Alternatively, the AP signals a single TID using 3 bits instead of the 8-bit TID bitmap 602. FIG. 7 shows a TIM bitmap 700 and a TID 702 in a TIM element. The 3-bit TID is signaled to each STA / MLD with an AID corresponding to the TIM bit set to 1. If frames belonging to multiple TIDs are buffered in the AP MLD for non-AP MLD, the signaled TID can be based on criteria specific to a particular implementation. The AP delivers MPDUs belonging to the indicated TID on the link that the STA / MLD wakes up. The MPDU carries an A-Control (TID control) field signaling additional TIDs for which the AP has BUs for non-AP MLD. It should be noted that even if legacy STAs do not recognize the TID indication, the TID indication is also required for non-AP MLDs so that they can find the correct TID indication.

[0038] As mentioned above, regardless of the method used to signal additional information about buffered BUs (e.g., link mapping, link set indication with link recommendation, and TID indication as shown in FIGS. 3-7), an additional bitmap is required for each bit set to 1 in the TIM element in order for non-AP MLDs (including legacy STAs and non-MLD EHT STAs) to correctly understand their position in the link / TID information set. Therefore, to solve the above-mentioned problems and reduce the overhead required to signal additional information about buffered BUs in WLAN networks that include MLD, a communication device and communication method that supports a multilink traffic indication map are needed.

[0039] According to the present disclosure, two solutions are proposed. Specifically, a presence bitmap is carried in a beacon / TIM / FILS discovery / OPS frame to indicate whether corresponding link / TID / AC information related to buffered BUs for non-AP STAs / MLDs exists in the link / TID / AC information set. The presence bitmap can still carry implicit information about the link even if the bit is set to 0.

[0040] Additionally, a "Starting AID" field is carried in Beacon / TIM / FILS discovery / OPS frames to indicate the smallest AID (e.g., the AID of the first non-AP MLD) associated with the non-AP MLD for which the Link / TID / AC information set contains the Link / TID / AC information. To further reduce the overhead of the Link / TID / AC information set, different portions (e.g., AID space) can be reserved for allocating AIDs to legacy STAs / non-MLD Very High Throughput (EHT) STAs and for allocating AIDs to non-AP MLDs.

[0041] FIG. 8 shows a schematic diagram illustrating an example configuration of a communication device 800 according to the present disclosure. The communication device 800 can be implemented as an AP and an STA and can be configured to support a multilink traffic indication map according to the present disclosure. As shown in FIG. 8, the communication device 800 can include a circuit 814, at least one wireless transmitter 802, at least one wireless receiver 804, and at least one antenna 812 (for simplicity, only one antenna is depicted in FIG. 8 for illustrative purposes). The circuit 814 can include at least one controller 806, which is used to perform, with the assistance of software and hardware, the tasks that the at least one controller 806 is designed to perform, including controlling communications with one or more other communication devices in a multiple-input, multiple-output (MIMO) wireless network. The circuit 814 can further include at least one transmit signal generator 808 and at least one receive signal processor 810. The at least one controller 806 can control at least one transmit signal generator 808 to generate MAC frames (e.g., data frames, management frames, and action frames) to be transmitted via the at least one wireless transmitter 802, and can further control at least one receive signal processor 810 to process MAC frames (e.g., data frames, management frames, and action frames) received from one or more other communication devices via the at least one wireless receiver 804. The at least one transmit signal generator 808 and the at least one receive signal processor 810 can be independent modules of the communication device 800 that communicate with the at least one controller 806 for the functions described above, as shown in FIG. 8 . Alternatively, the at least one transmit signal generator 808 and the at least one receive signal processor 810 can be included in the at least one controller 806. It will be understood by those skilled in the art that the arrangement of these functional modules is flexible and may vary depending on actual needs and / or requirements.The data processing unit, storage unit, and other associated control units may be provided on an appropriate circuit board and / or chipset. In various embodiments, in operation, the at least one wireless transmitter 802, the at least one wireless receiver 804, and the at least one antenna 812 may be controlled by the at least one controller 806.

[0042] In operation, the communications device 800 provides functionality necessary for a multilink traffic indication map. For example, the communications device 800 may be an AP among multiple APs belonging to an AP MLD (each of the multiple APs operates on a corresponding link of the AP MLD), and a circuit (e.g., at least one transmit signal generator 808 of the circuit 814) in operation generates a frame including a traffic indication map (TIM) element and a presence bitmap. The TIM element includes a partial virtual bitmap (PVM) indicating the presence of one or more buffered units for either a non-AP STA or a non-AP MLD associated with the AP or AP MLD, and the presence bitmap indicates whether additional information related to one or more BUs is present in a frame intended for either a non-AP STA or a non-AP MLD. The wireless transmitter 802 in operation can transmit the frame on the link.

[0043] For example, the communications device 800 may be one of a plurality of STAs belonging to a non-AP MLD associated with an AP MLD (each of the plurality of STAs operating on a corresponding link of the non-AP MLD), and the wireless receiver 804, in operation, receives a frame on the link. The frame includes a traffic indication map (TIM) element and a presence bitmap, where the TIM element includes a partial virtual bitmap (PVM) indicating the presence of one or more buffered units for the non-AP MLD, and the presence bitmap indicates whether additional information related to one or more BUs is present in the frame intended for the non-AP MLD. A circuit (e.g., at least one receive signal processor 810 of the circuit 814), in operation, can process the frame.

[0044] In one embodiment, the frame transmitted / received by the communication device 800 further includes a starting AID (association identifier) ​​indicating the smallest AID for which additional information related to one or more BUs is present in the frame. In yet another embodiment, a first part of the PVM of the TIM element is associated with AIDs assigned to legacy STAs and non-MLD EHT STAs, and a second part of the PVM of the TIM element is associated with AIDs assigned to non-AP MLDs, and the first and second parts of the TIM element do not overlap.

[0045] 9 shows a flowchart 900 illustrating a communication method for a multilink traffic map according to various embodiments of the present disclosure. In step 902, a step of generating a frame including a traffic indication map (TIM) element and a presence bitmap is performed, where the TIM element includes a partial virtual bitmap (PVM) indicating the presence of one or more buffered units for one of non-AP STAs or non-AP MLDs associated with the AP or AP MLD, and the presence bitmap indicates whether additional information related to one or more BUs is present in the frame intended for one of the non-AP STAs or non-AP MLD. In step 904, a step of transmitting the frame on the link is performed.

[0046] 10 illustrates an exemplary beacon / TIM frame 1000. While a beacon / TIM frame format is shown, it will be understood that the same format can be applied to a Fast Initial Link Setup (FILS) Discovery frame or an Operation (OPS) frame. The beacon / TIM frame 1000 conveys a TIM element 1002 containing a partial virtual bitmap (PVM) 1008, a link / TID / AC information presence bitmap 1004, and a link / TID / AC information set 1006 containing link / TID / AC information for each associated MLD. The presence bitmap 1004 indicates whether corresponding link / TID / AC information associated with a buffered BU for a non-AP MLD is present in the presence bitmap 1004.

[0047] Link / TID / AC information presence bitmap 1004 contains one bit for every bit set to one in TIM element 1002, in the same order as PVB 1008. A bit in presence bitmap 1004 is set to one if the corresponding entry of link / TID / AC information is present in link / TID / AC information set 1006, and is set to zero otherwise.

[0048] The bit corresponding to the legacy STA is always set to 0. On the other hand, the bit corresponding to the MLD is set to 1 if the link / TID / AC information for the MLD exists in the link / TID / AC information set 1006, for example, if the AP MLD is buffering BUs for the non-AP MLD on other links, or if the AP MLD recommends the non-AP MLD to obtain BUs on other links, or if the AP MLD needs to signal BUs for TIDs mapped to other links. Otherwise, the bit is set to 0. For example, if the AP MLD is buffering BUs for a non-AP MLD on the same link (referred to herein as the "current link" but which may also be referred to as the "transmission link") on which the TIM frame / beacon frame 1000 carrying the TIM element is transmitted, or if the AP MLD recommends the non-AP MLD to acquire BUs on the current link, or if all BUs for the non-AP MLD belong to a TID that is exclusively mapped to the current link, or for a single-link EHT STA or single-link non-AP MLD that listens to beacons on only one link, the bit is set to 0 on all links. Advantageously, the bit set to 0 still conveys implicit information about the current link, and the link / TID / AC information is only present for MLDs that need the information. Using the presence bitmap 1004 in the beacon frame / TIM frame 1000, the non-AP MLD is configured to check its corresponding bit in the presence bitmap 1004 if its corresponding bit in the PVB 1008 is set to 1, and if its bit in the presence bitmap 1004 is set to 1, to further check the corresponding entry in the link / TID / AC information set 1006 to obtain further information about the BU associated with the link / TID / AC.

[0049] According to the present disclosure, the same AID is assigned to MLD across all links, but legacy STAs are assigned unique AIDs on each link, i.e., different legacy STAs may be assigned the same AID on different links. Advantageously, there are no restrictions on how AIDs are assigned by AP MLD.

[0050] FIG. 11 illustrates exemplary AID assignments and three exemplary TIM bitmaps 1100, 1110, and 1120 transmitted by the AP-MLDs on three links, respectively. MLDs 1, 2, and 3, which operate on all three links (Link 1, Link 2, and Link 3), and single-link MLD 4, are assigned the same AIDs 12, 28, 57, and 77 across the three links, respectively, while legacy STAs are assigned unique AIDs on their respective operational links. Notably, the same AID 35 is assigned to different legacy STAs (Legacy 1 and Legacy 2) on Link 1 and Link 2, while Link 3 is not assigned an AID 35. Various embodiments of the present disclosure, described below with reference to accompanying FIGS. 12-16, are based on the exemplary AID assignment used in the exemplary TIM bitmap 1100.

[0051] In one embodiment, the presence bitmap 1004 shown in FIG. 10 can be a link mapping bitmap (LMB), the link / TID / AC information set 1006 shown in FIG. 10 is an LMB set, and the presence bitmap indicates whether a corresponding LMB exists in the LMB set. A bit corresponding to a legacy STA is always set to 0. On the other hand, a bit corresponding to an MLD is set to 0 if the BU is only available on the link on which the TIM frame / beacon frame carrying the TIM element is transmitted, for example, due to TID-link mapping or because the MLD operates only on that link, and is set to 1 if the BU is also available on other links. The LMB presence bitmap contains one bit for every bit set to 1 in the TIM bitmap, in the same order as the TIM bitmap, and the LMB set contains one LMB for every bit set to 1 in the LMB presence bitmap, in the same order as the LMB presence bitmap. Advantageously, a bit set to 0 in the LMB presence bitmap indicates that the corresponding non-AP MLD only needs to acquire a BU on the current link, and no LMB is required in the LMB set, reducing the overhead of link / TID / AC information.

[0052] 12 shows an example TIM bitmap 1200, an example LMB presence bitmap 1202, and an example LMB set 1204 in a TIM frame / beacon frame. In TIM bitmap 1200, the TIM bits corresponding to AIDs 12, 28, 35, 57, and 77, which are assigned to MLD 1, MLD 2, Legacy 1, MLD 3, and Single-Link MLD 4, respectively, are set to 1, indicating that the AP MLD has one or more buffered frames to transmit to these STAs / MLDs. LMB presence bitmap 1202 contains one bit for every bit set to 1 in TIM bitmap 1200, in the same order as TIM bitmap 1200; therefore, LMB presence bitmap 1202 has a total size of 5 bits.

[0053] In this example, the AP MLDs transmitting TIM frames / beacon frames operate on three links (Link 1, Link 2, and Link 3), and the TIM frames / beacon frames transmitted on Link 1 (referred to herein as the current link) are shown. MLD 1 only has BUs with TIDs mapped to Link 1, while MLD 4 only operates on Link 1 in this example. Because the BUs with TIDs for MLD 1 and MLD 4 are mapped to the current link (Link 1), no additional information is needed for MLD 1 and MLD 4; only LMBs for MLD 2 and MLD 3 are present or needed in the LMB set. Bits 1 and 5 of the LMB presence bitmap 1202 corresponding to MLD 1 and MLD 4 are set to 0, indicating that the BUs are available only on the current link (Link 1). Meanwhile, the second and fourth bits of the LMB presence bitmap 1202 corresponding to MLD 2 and MLD 3 are set to 1, indicating that the BUs of MLD 2 and MLD 3 are also available on other links (Link 2, Link 3). Legacy 1 is a legacy STA, and therefore the third bit of the LMB presence bitmap 1202 corresponding to Legacy 1 is always set to 0.

[0054] LMB set 1204 contains one LMB for every bit set to 1 in LMB presence bitmap 1202, in the same order as LMB presence bitmap 1202. In this case, each LMB contains three bits corresponding to three different links (Link 1, Link 2, and Link 3), so LMB set 1204 has a total size of 6 bits. The bit of the LMB corresponding to the MLD is set to 1 to indicate that BUs are available on the corresponding link. In this case, the first LMB in LMB set 1204 corresponding to MLD 2 has its second and third bits set to 1, indicating that BUs for MLD 2 are available on Link 2 and Link 3. In this example, the total overhead for link / TID / AC information using LMB presence bitmap 1202 (5 bits) and LMB set 1204 (6 bits) is 11 bits.

[0055] In another embodiment, the presence bitmap 1004 can be a link recommendation (LR) presence bitmap, and the link / TID / AC information set 1006 is an LR bitmap set. For the default TID-to-link mapping where a TID is mapped to all valid links, the LR presence bitmap indicates whether a corresponding LR bitmap exists in the LR bitmap set. The bit corresponding to the MLD is set to 0 if the link on which the TIM frame / beacon frame carrying the TIM element is transmitted is recommended or if the AP MLD has no link recommendation, and is set to 1 if a link other than the current link is recommended.

[0056] The LR presence bitmap contains one bit for every bit set to 1 in the TIM bitmap, in the same order as the TIM bitmap, and the LR bitmap set contains one LR bitmap for every bit set to 1 in the LR presence bitmap, in the same order as the LR presence bitmap. Unlike LMB, the current link is excluded from the LR bitmap because the current link can be promoted by setting the corresponding bit in the LR presence bitmap to 0. Advantageously, a bit set to 0 in the LR presence bitmap indicates that the corresponding non-AP MLD only needs to obtain BUs on the current link, so no LR bitmap is needed in the LR bitmap set, reducing the overhead of link / TID / AC information.

[0057] 13 shows an example TIM bitmap 1300, an example LR presence bitmap 1302, and an example LR bitmap set 1304 in a TIM frame / beacon frame. In TIM bitmap 1300, the TIM bits corresponding to AIDs 12, 28, 35, 57, and 77, which are assigned to MLD 1, MLD 2, Legacy 1, MLD 3, and Single Link MLD 4, respectively, are set to 1, indicating that the AP MLD has one or more buffered frames to transmit to these STAs / MLDs. LR presence bitmap 1302 contains one bit for every bit set to 1 in TIM bitmap 1300, in the same order as TIM bitmap 1300; therefore, LR presence bitmap 1302 has a total size of 5 bits.

[0058] In this example, the AP MLD transmitting the TIM frame / beacon frame operates on three links (Link 1, Link 2, and Link 3), and the TIM frame / beacon frame is transmitted on Link 1 (referred to herein as the current link). MLD 1 only has BUs for TIDs mapped to Link 1, while MLD 4 only operates on Link 1. Because the BUs for TIDs of MLD 1 and MLD 4 are mapped to the current link (Link 1), no additional information is needed for MLD 1 and MLD 4, and only the LR bitmaps for MLD 2 and MLD 3 are present or needed in LR bitmap set 1304. The first and fifth bits of the LR presence bitmap 1302 corresponding to MLD 1 and MLD 4 are set to 0, indicating that the BUs are available only on the current link (Link 1), while the second and fourth bits of the LR presence bitmap 1302 corresponding to MLD 2 and MLD 3 are set to 1, indicating that the BUs of MLD 2 and MLD 3 are also available on other links (Link 2, Link 3). Legacy 1 is a legacy STA, and therefore the third bit of the LR presence bitmap 1302 corresponding to Legacy 1 is always set to 0.

[0059] The LR bitmap set 1304 contains one LR for every bit set to 1 in the LR presence bitmap 1202, in the same order as the LR presence bitmap 1202. In this case, each LR bitmap contains two bits corresponding to two different links (Link 2 and Link 3) other than the current link (Link 1), so the LR bitmap set 1304 has a total size of 4 bits. When a bit in an LR bitmap corresponding to an MLD is set to 1, it indicates that a BU on a link other than the current link is recommended. In this case, the first LR bitmap in the LR bitmap set 1304 is associated with MLD 2 and has its first bit set to 1, indicating that Link 2 is recommended for MLD 2. The second LR bitmap in the LR bitmap set 1304 is associated with MLD 3 and has its second bit set to 1, indicating that Link 3 is recommended for MLD 3. The total overhead for link / TID / AC information using LR presence bitmap 1302 (5 bits) and LR set 1304 (4 bits) is 9 bits.

[0060] In addition to being used in the default TID-link mapping, the LR Present Bitmap and LR Bitmap Set can also be used when different TIDs are mapped to different link sets. Here, a link set is a link set in which one or more valid links are grouped. In such a case, the Present Bitmap can be a Link Set Present Bitmap, and the Link / TID / AC Information Set is a Link Set Bitmap Set. The Link Set Present Bitmap indicates whether a corresponding link set bitmap exists in the Link Set Bitmap Set. The bit corresponding to MLD is set to 0 if the link on which the TIM frame / beacon frame carrying the TIM element is transmitted is the only link in the link set and only this link set has a BU, and is set to 1 if the other link sets have a BU.

[0061] The linkset present bitmap contains one bit for every bit set to 1 in the TIM bitmap, in the same order as the TIM bitmap, and the linkset bitmap set contains one linkset bitmap for every bit set to 1 in the linkset present bitmap, in the same order as the linkset present bitmap. The LR bitmap set can further use bits set to 1 in the linkset bitmap set to indicate which links in the linkset have a BU present.

[0062] 14 shows an example TIM bitmap 1400, an example linkset present bitmap 1402, an example linkset bitmap set 1404, and an example LR bitmap set 1406. In TIM bitmap 1400, the TIM bits corresponding to AIDs 12, 28, 35, 57, and 77, which are assigned to MLD 1, MLD 2, Legacy 1, MLD 3, and Single-Link MLD 4, respectively, are set to 1, indicating that the AP MLD has one or more buffered frames to transmit to these STAs / MLDs. Linkset present bitmap 1402 contains one bit for every bit set to 1 in TIM bitmap 1400, in the same order as TIM bitmap 1400; therefore, linkset present bitmap 1402 has a total size of 5 bits.

[0063] In this example, the AP MLD transmitting the TIM frame / beacon frame operates on three links (Link 1, Link 2, and Link 3), and the TIM frame / beacon frame is transmitted on Link 3 (referred to herein as the current link or current link set). TIDs 0-3 are mapped to Link 1 and Link 2, and therefore Link 1 and Link 2 can be classified into a link set (Link Set 1), and TIDs 4-7 are mapped to Link 3, which is classified as another link set (Link Set 2). MLD 1 and MLD 2 only have BUs for TIDs mapped to Link Set 2 (i.e., Link 3), while MLD 4 operates only on Link 3. Because the BUs for TIDs of MLD 1, MLD 2, and MLD 4 are mapped to the current link set (Link Set 2 or Link 3), no additional information is needed for MLD 1, MLD 2, and MLD 4, and only the link set bitmap for MLD 3 is present or needed in link set bitmap set 1404. The first, second, and fifth bits of the linkset presence bitmap 1402 corresponding to MLD 1, MLD 2, and MLD 4 are set to 0, indicating that the BU is available only on the current linkset, while the fourth bit of the linkset presence bitmap 1402 corresponding to MLD 3 is set to 1, indicating that the BU is also available on the other linkset (linkset 1). Legacy 1 is a legacy STA, and therefore the third bit of the linkset presence bitmap 1402 corresponding to Legacy 1 is always set to 0.

[0064] The linkset bitmap set 1404 contains one linkset bitmap for every bit set to 1 in the linkset presence bitmap 1402, in the same order as the linkset presence bitmap 1402. In this case, each linkset bitmap contains two bits corresponding to two different linksets (linkset 1, linkset 2), so the linkset bitmap set 1404 (which contains only one linkset bitmap) has a total size of 2 bits. When a bit in a linkset bitmap corresponding to an MLD is set to 1, it indicates that a BU is present in that linkset. In this case, the first bit in the linkset bitmap set associated with MLD 3 is set to 1, indicating that a BU for MLD 3 is present in linkset 1. The LR bitmap set 1406 contains one LR bitmap for every bit set to 1 in the linkset bitmap set 1404. The bit in the LR bitmap corresponding to a linkset's link indicates whether a BU is present on that linkset. In this case, the LR bitmap in LR bitmap set 1406 associated with MLD 3 has its second bit set to 1, indicating that a BU is present on link 2 of linkset 1. The total overhead for link / TID / AC information using linkset presence bitmap 1402 (5 bits), linkset bitmap set 1404 (2 bits), and LR bitmap set 1406 (2 bits) is 9 bits.

[0065] 10 can be a TID information presence bitmap, and the link / TID / AC information set 1006 is a TID information bitmap set, where the TID information presence bitmap indicates whether corresponding TID information exists in the TID information bitmap set. The bit corresponding to the MLD is set to 0 if the buffered BU belongs only to the TID mapped to the link on which the TIM frame / beacon frame carrying the TIM element is transmitted, and is set to 1 if BUs of TIDs mapped to other links are also buffered.

[0066] The TID information present bitmap contains one bit for every bit set to 1 in the TIM bitmap, in the same order as the TIM bitmap, and the TID information bitmap set contains one TID information bitmap for every bit set to 1 in the TID information present bitmap, in the same order as the TID information present bitmap. Advantageously, if a bit in the TID information present bitmap is set to 0 for a non-AP MLD, the non-AP MLD only needs to acquire BUs on the current link and no TID information bitmap is needed in the TID information bitmap set, reducing link / TID / AC information overhead.

[0067] 15 shows an exemplary TIM bitmap 1500, TID information present bitmap 1502, and TID information bitmap set 1506 in a TIM frame / beacon frame. In TIM bitmap 1500, the TIM bits corresponding to AIDs 12, 28, 35, 57, and 77, which are assigned to MLD 1, MLD 2, Legacy 1, MLD 3, and Single-Link MLD 4, respectively, are set to 1, indicating that the AP MLD has one or more buffered frames to transmit to these STAs / MLDs. TID information present bitmap 1502 contains one bit for every bit set to 1 in TIM bitmap 1500, in the same order as the TIM bitmap; therefore, the TID information present bitmap has a total size of 5 bits.

[0068] In this example, the AP MLDs transmitting the TIM frames / beacon frames operate on three links (Link 1, Link 2, and Link 3), and the TIM frames / beacon frames are transmitted on Link 1 (referred to herein as the current link). MLD 1 only has BUs of TIDs mapped to Link 1, while MLD 4 operates only on Link 1. Because the BUs of TIDs for MLD 1 and MLD 4 are mapped to the current link, no additional information is needed for MLD 1 and MLD 4, and only TID information bitmaps for MLD 2 and MLD 3 are present or needed in TID information bitmap set 1504. The first and fifth bits of TID information presence bitmap 1502 corresponding to MLD 1 and MLD 4 are set to 0, indicating that the buffered BUs for MLD 1 and MLD 4 belong only to TIDs mapped to the current link (Link 1). In contrast, the second and fourth bits of the TID information presence bitmap 1502 corresponding to MLD 2 and MLD 3 are set to 1, indicating that the respective BUs of TIDs mapped to other links (Link 2 and Link 3) are also buffered. Legacy 1 is a legacy STA, and therefore the third bit of the TID information presence bitmap corresponding to Legacy 1 is always set to 0.

[0069] The TID information bitmap set 1504 includes one TID information bitmap for every bit set to 1 in the TID information presence bitmap 1502, in the same order as the TID information presence bitmap 1502. In this case, each TID information bitmap includes 8 bits corresponding to eight TIDs (TIDs 0 to 7), and therefore the TID information bitmap set 1504 has a total size of 16 bits. The bit of the TID information bitmap corresponding to an MLD is set to 1 if BUs for the respective TIDs mapped to other links (Link 2, Link 3) are also buffered. In this case, the TID information bitmaps in the TID information bitmap set 1504 are associated with MLD 2 and MLD 3, and their second through seventh bits (corresponding to TIDs 1 to 6) are set to 1, indicating that BUs for TIDs 1 to 6 mapped to other links are also buffered. The total overhead for link / TID / AC information in this case using TID information present bitmap 1502 (5 bits) and TID information bitmap set 1504 (16 bits) is 21 bits.

[0070] Alternatively, instead of the TID information bitmap (8 bits), a single TID (3 bits) may be signaled, similar to the method described in Figure 7, but only for the bits of the MLDs (in this case MLD 2 and MLD 3) that are set to 1 in the TID information present bitmap 1502.

[0071] Also, in one embodiment, TID-link mapping is performed per access category (AC), i.e., two TIDs of an AC are always mapped to a link together, never separately. In such an embodiment, the presence bitmap can be an AC information presence bitmap, the link / TID / AC information set is an AC information bitmap set, and the AC information presence bitmap indicates whether corresponding AC information is present in the AC information bitmap set. A bit corresponding to an MLD is set to 0 if only BUs of TIDs of ACs mapped to the link on which the TIM frame / beacon frame carrying the TIM element is transmitted (referred to herein as the current link) are buffered, and is set to 1 if BUs of TIDs of ACs mapped to other links are also buffered. Advantageously, if a bit in the AC information presence bitmap for a non-AP MLD is set to 0, that non-AP MLD only needs to acquire BUs on the current link.

[0072] The AC information present bitmap contains one bit for every bit set to 1 in the TIM bitmap, in the same order as the TIM bitmap, and the AC information bitmap set contains one AC information bitmap for every bit set to 1 in the AC information present bitmap, in the same order as the AC information present bitmap. Advantageously, if a bit in the AC information present bitmap for a non-AP MLD is set to 0, that non-AP MLD only needs to acquire BUs on the current link, and no AC information bitmap is needed in the AC information bitmap set, reducing link / TID / AC information overhead.

[0073] 16 shows an example TIM bitmap 1600, an example AC information present bitmap 1602, and an example AC information bitmap set 1604 in a TIM frame / beacon frame. In TIM bitmap 1600, the TIM bits corresponding to AIDs 12, 28, 35, 57, and 77, which are assigned to MLD 1, MLD 2, Legacy 1, MLD 3, and Single-Link MLD 4, respectively, are set to 1, indicating that the AP MLD has one or more buffered frames to transmit to these STAs / MLDs. AC information present bitmap 1602 contains one bit for every bit set to 1 in TIM bitmap 1600, in the same order as TIM bitmap 1600; therefore, TIM information present bitmap 1602 has a total size of 5 bits.

[0074] In this example, the AP MLD transmitting the TIM frame / beacon frame operates on three links (Link 1, Link 2, and Link 3), and the TIM frame / beacon frame is transmitted on Link 1 (referred to herein as the current link). There are four ACs: AC_BK, AC_BE, AC_VI, and AC_VO. Two TIDs are mapped to each of the four ACs. An example of AC-TID mapping is shown in Table 1 below. The two TIDs for each AC are always mapped to a link. In this example, AC_VO and AC_VI are mapped to Link 1 and Link 2, and AC_BE and AC_BK are mapped to Link 3.

[0075] MLD 1 only has BUs for ACs mapped to link 1, while MLD 4 only operates on link 1. Because the BUs for ACs in MLD 1 and MLD 4 are mapped to the current link, no additional information is needed for MLD 1 and MLD 4, and only AC information bitmaps for MLD 2 and MLD 3 are present or needed in AC information bitmap set 1604. Bits 1 and 5 of AC information presence bitmap 1602 corresponding to MLD 1 and MLD 4 are set to 0, indicating that only BUs for TIDs of ACs mapped to the current link (link 1) are buffered. Meanwhile, bits 2 and 4 of AC information presence bitmap 1602 corresponding to MLD 2 and MLD 3 are set to 1, indicating that those BUs for ACs mapped to other links (link 2 and link 3) are also buffered. Legacy 1 is a legacy STA, and therefore bit 3 of AC information presence bitmap 1602 corresponding to Legacy 1 is always set to 0. [Table 1]

[0076] The AC information bitmap set 1604 includes one AC information bitmap for every bit set to 1 in the AC information presence bitmap 1602, in the same order as the AC information presence bitmap 1602. In this case, each AC information bitmap includes 4 bits corresponding to four ACs (AC_BK, AC_BE, AC_VI, AC_VO), and therefore the AC information bitmap set 1604 has a total size of 8 bits. In this case, the total overhead for link / TID / AC information using the AC information presence bitmap 1602 (5 bits) and the AC information bitmap set 1604 (8 bits) is 13 bits.

[0077] According to the present disclosure, different portions of the TIM bitmap (e.g., AID space) can be reserved for allocating AIDs to legacy STAs / non-MLD Very High Throughput (EHT) STAs and for allocating AIDs to non-AP MLDs, where the different portions do not overlap.

[0078] 17 shows an example AID allocation and three example TIM bitmaps 1700, 1710, and 1720 transmitted from the AP MLD on three links, respectively. In this example, 255 consecutive AIDs (out of a maximum of 2007) are used by the AP MLD, with the first AID (0) being used to indicate group-addressed frames and not assigned to a STA. The next 30 AIDs (1-30) are reserved for legacy STAs and single-link EHT STAs, and the remaining AIDs (31-255) are used for non-AP MLD.

[0079] Each TIM bit is mapped to an AID. Thus, following the first TIM bit associated with AID 0, the next portion of the TIM bitmap (in this case, the portion associated with AIDs 1-30) is reserved for legacy and non-MLD EHT STAs (referred to herein as the non-MLD STA AID space), and the remaining portion of the TIM bitmap is used for non-AP MLD (referred to herein as the non-AP MLD AID space). Advantageously, this AID allocation can reduce link / TID / AC information overhead.

[0080] Therefore, due to the AID assignment, the link / AID / AC information associated with the buffered BU is present in the link / AID / AC information set only for the non-AP MLD. The Starting AID field can be used to indicate the first non-AP MLD AID (e.g., the smallest AID) in the non-AP MLD's AID space whose link / AID / AC information is included in the link / TID / AC information set. Various embodiments of the present disclosure described below with reference to accompanying Figures 19 and 21 are based on the example AID assignment used in the example TIM bitmap 1710.

[0081] 18 illustrates an exemplary beacon / TIM frame 1800. While a beacon / TIM frame format is shown, it will be understood that the same format can be applied to a Fast Initial Link Setup (FILS) Discovery frame or an Operations (OPS) frame. The beacon / TIM frame 1800 carries a TIM element 1802 that contains a Partial Virtual Bitmap (PVM) 1808, a Starting AID field 1804, and a Link / TID / AC Information Set 1806 that contains the Link / TID / AC information for each of the associated MLDs.

[0082] 19 shows an exemplary TIM bitmap 1900 and LMB set 1904 in a beacon frame / TIM frame. In the TIM bitmap 1900, if the AP MLD has one or more buffered frames to send to non-AP STAs / MLDs on any of the links used, the TIM bit is set to 1. The TIM bits corresponding to AIDs 11, 12, 35, 57, 77, and 255, which are assigned to Legacy 2, Single-Link EHT STAs, MLD 1, MLD 2, MLD 3, and Single-Link MLD 4, respectively, are set to 1, indicating that the AP MLD has one or more buffered frames to send to these STAs / MLDs.

[0083] The Starting AID field 1902 indicates the lowest AID allocated to the non-AP MLD that has the TIM bit set to 1 (i.e., link / TID / AC information present in the frame). In this case, the Starting AID is 35. The allocation of the non-AP MLD's AID space and Starting AID in the TIM bitmap eliminates the need for a presence bitmap, thus reducing the overhead of link / TID / AC information.

[0084] A non-AP MLD can locate its corresponding link / TID / AC information in the link / TID / AC information set based on the starting AID in the Starting AID field 1902 and the TIM bitmap 1900. Specifically, a starting AID of 35 indicates that the first entry in the link / TID / AC information set is associated with the non-AP MLD (in this case, MLD 1) assigned to AID 35.

[0085] 20 shows another exemplary beacon / TIM frame 2000. A link / TID / AC information presence bitmap 2005 can be used together with a Starting AID field 2004 to further reduce the overhead of the link / TID / AC information.

[0086] 21 shows an example TIM bitmap 2100, an example TID information presence bitmap 2104, and an example TID information bitmap set 2106 in a beacon / TIM frame. In TIM bitmap 2100, the TIM bits corresponding to AIDs 11, 12, 35, 57, 77, and 255, which are assigned to Legacy 2, Single-Link EHT STAs, MLD 1, MLD 2, MLD 3, and Single-Link MLD 4, respectively, are set to 1, indicating that the AP MLD has one or more buffered frames to transmit to these STAs / MLDs. In this example, the TIM is transmitted on Link 2, and the Starting AID field 2102 is set to the beginning of the non-AP MLD AID space (AID 31). The TID information present bitmap contains one bit for every bit set to 1 in the TIM bitmap, starting from the AID pointed to by the Starting AID field (i.e., 31). Through the allocation of non-AP MLD AID space in the TIM bitmap 2100 and the starting AID 2102, the TID information present bitmap 2104 for the non-MLD STA's AID space (AIDs 1-30) is omitted, thus reducing the link / TID / AC information overhead.

[0087] In this example, MLD 1 only has BUs for TIDs mapped to link 2, while MLD 4 only operates on link 1, and therefore TID information for MLD 4 is not included in link 2. No additional information of buffered BUs for MLD 1 and MLD 4 is needed, and only TID information bitmaps for MLD 2 and MLD 3 are present or needed in TID information bitmap set 2106. The second and third bits of TID information presence bitmap 2104, corresponding to MLD 2 and MLD 3, are set to 1, indicating that those BUs for TIDs mapped to other links are also buffered.

[0088] The TID information bitmap set contains one TID information bitmap for every bit set to 1 in the TID information present bitmap 2104, in the same order as the TID information present bitmap 2104. In this case, a single TID (3 bits) is signaled for each of MLD 2 and MLD 3, and therefore the TID information bitmap set 2106 has a total size of 6 bits. The 3-bit TIDs 101 and 111 signal that BUs for TID 5 and TID 7 are buffered for MLD 2 and MLD 3, respectively. If BUs for other TIDs exist, they are signaled in the A control field of subsequent data frames belonging to the indicated TIDs.

[0089] In one embodiment, for an AP that is a member of a multiple BSSID set (i.e., a virtual AP), bits 1 through 2 of the TIM bitmap are nThe bits 0-1 (-1) are used to indicate that one or more group-addressed frames are buffered for each AP (virtual AP) corresponding to a non-transmitting BSSID, and are called non-TxBSSIDs (NonTxBSSIDs). These bits are not assigned to STAs within the BSS. Furthermore, some AIDs may be reserved to signal the presence of group-addressed BUs of other APs in the AP MLD. These AIDs may occur immediately after the AIDs assigned to the virtual AP, if any. AP MLDs can also reduce the link / TID / AC information overhead for legacy STAs by appropriately planning the AID space for associated non-AP STAs / MLDs. For example, an AP MLD can assign AIDs to associated non-AP MLDs from the AID space starting immediately after the last AID reserved for the AP (e.g., 3), while associated non-MLD STAs are assigned AIDs from the AID space starting after the AID space reserved for non-AP MLDs.

[0090] 22 shows an example TIM bitmap 2200 sent on a link from an AP MLD, as well as example formats for an AC information presence bitmap 2202 and an AC information bitmap set 2204. In this example, 255 consecutive AIDs (out of a maximum of 2008) are used by the AP MLD, with the first four AIDs (0-3) used to indicate group-addressed frames corresponding to four virtual APs, the next 200 AIDs (4-203) reserved for non-AP MLDs operating on multiple links, and the remaining AIDs (204-255) used for legacy STAs and single-link EHT STAs.

[0091] Each TIM bit is mapped to an AID. Thus, the beginning portion 2211 of the TIM bitmap 2200 (in this case, the TIM bits associated with AIDs 0-3) is reserved for AP MLD (referred to herein as the AP MLD AID space). Following the AP MLD AID space 2211, the next portion 2212 of the TIM bitmap (in this case, the portion associated with AIDs 11-203) is reserved for non-AP MLD (referred to herein as the non-AP MLD AID space), and the remaining portion 2213 of the TIM bitmap is reserved for legacy STAs and non-MLD EHT STAs (referred to herein as the non-MLD STA AID space).

[0092] The non-AP MLD AID space 2212 starts immediately (appendix) to the AID space 2211 reserved for the AP in the TIM bitmap 2200. Single-link MLDs (e.g., single-link MLD 4 in FIG. 22) can also be assigned AIDs from the non-MLD STA AID space; thus, the non-AP MLD AID space 2212 is reserved exclusively for non-AP MLDs operating on multiple links. Instead of a fixed AID space, it is also possible for the AID space boundaries to be ill-defined. For example, non-AP MLDs operating on multiple links are assigned AIDs consecutively starting from the first available AID (e.g., 4, 5, 6, ...), while legacy STAs and single-link EHT STAs are assigned AIDs consecutively starting from the last AID in the AP's AID space (e.g., 255, 254, 253, ...). Advantageously, the AID space reserved for the AP (eg, NonTxBSS ID) is known to all associated STAs, so the starting AID is known and can be omitted in this scheme.

[0093] Returning to Figure 22, with this AID assignment, the presence bitmap only needs bits for non-AP MLDs because link / AID / AC information related to buffered BUs exists only for non-AP MLDs, while legacy STAs and non-MLD EHT STAs are not included in the link / AID / AC information set. The TIM bits corresponding to AIDs 12, 28, 35, 56, 204, 227, and 225 assigned to MLD 1, MLD 2, MLD 3, single-link MLD 4, MLD 1, MLD 2, MLD 3, and single-link MLD 4, respectively, are set to 1, indicating that the AP MLD has one or more buffered frames to transmit to these STAs / MLDs. In this example, the TIM is transmitted on link 3. MLD 1 only has BUs with TIDs mapped to link 3, while MLD 4 only operates on link 1, so no AC information for MLD 4 is included. No additional information of buffered BUs for MLD 1 and MLD 4 is needed; only AC information bitmaps for MLD 2 and MLD 3 are present or needed in AC information bitmap set 2204. The second and third bits of AC information presence bitmap 2202 corresponding to MLD 2 and MLD 3 are set to 1, indicating that those BUs of ACs mapped to other links are also buffered.

[0094] The AC information bitmap set 2204 contains one AC information bitmap for every bit set to 1 in the AC information presence bitmap 2202, in the same order as the AC information presence bitmap 2202. In this case, each AC information bitmap contains four bits corresponding to four ACs (AC_BK, AC_BE, AC_VI, AC_VO), and therefore the AC information bitmap set 2204 has a total size of 8 bits. The total overhead for link / TID / AC information using the AC information presence bitmap (3 bits) and the AC information bitmap set (8 bits) is 11 bits.

[0095] In yet another embodiment, even if there is no restriction on AID assignment, the overhead of link / TID / AC information can be reduced by indicating the starting AID using, for example, the Starting AID field, and excluding STAs with AIDs smaller than the starting AID. The excluded STAs can be legacy STAs, non-MLD EHT STAs, and even MLDs for which link / TID / AC information does not exist.

[0096] 23 shows an example TIM bitmap 2300, an example TID information presence bitmap 2304, and an example TID information bitmap set 2306 in a beacon / TIM frame. The TIM bits corresponding to AIDs 11, 12, 35, 57, 77, and 255 assigned to Legacy 2, Single-Link EHT STA, MLD 1, Legacy 7, MLD 3, and Single-Link MLD 4, respectively, are set to 1, indicating that the AP MLD has one or more buffered frames to transmit to these STAs / MLDs. Absent any restrictions on AID assignment, AIDs for legacy STAs (e.g., Legacy 7) and non-AP MLDs may be mixed. The Starting AID field 2302 may indicate the AID of the first non-AP MLD whose link / TID / AC information is included in the link / TID / AC information set (i.e., the smallest AID associated with a non-AP MLD). In this case, the Starting AID field 2302 indicates 35 as the starting AID. This easily excludes Legacy 2 and single-link EHT STAs from the TID information bitmap set. Legacy and non-MLD EHT STAs are still included in the Link / TID / AC information set, but only STAs with an AID higher than the Starting AID (e.g., Legacy 7).

[0097] TID information present bitmap 2304 contains one bit for every bit set to 1 in the TIM bitmap, in the same order as TIM bitmap 2300, so that TID information present bitmap 2304 has a total size of 4 bits. In this case, the first and third bits corresponding to MLD 1 and MLD 3 are set to 1 in TID information present bitmap 2304. TID information bitmap set 2306 contains one TID information bitmap (in this case a single 3-bit TID) for every bit set to 1 in TID information present bitmap 2304, in the same order as TID information present bitmap 2304. In this case, the first and third bits corresponding to MLD 1 and MLD 3 are set to 1 in TID information present bitmap, so that TID information bitmap set 2306 has a size of 6 bits. The total overhead for link / TID / AC information in this case using TID information present bitmap 2304 (4 bits) and TID information bitmap set 2306 (6 bits) is 10 bits.

[0098] 24 shows an example format of a Multi-link TIM 2400. The Multi-link TIM 2400 can be a new element or a Multi-link element with the Type field set to "Multi-link TIM" defined to carry a presence bitmap and link / TID / AC information set. The Multi-link TIM element includes an Element field, a Length field, an Element ID Extension field, a Multi-link Control field containing a Type field (set to "Multi-link TIM") and a presence bitmap, a Common Info field, and a Link Info field.

[0099] The Presence Bitmap field of the Multi-link Control field further includes a Starting AID Present field and a Presence Bitmap Size Present field, which are used to indicate the presence of the Starting AID field and the Presence Bitmap Size field in the Common Info field. The Common Info field further includes a Link / TID / AC Information Type field, a Starting AID field, and a Presence Bitmap Size field. The Link Info field further includes a Link / TID / AC Information Presence Bitmap Present field, a Link / TID / AC Information Presence Bitmap field, and a Link / TID / AC Information Set field. The Link / TID / AC Information Type field indicates what kind of information is conveyed in the Link / TID / AC Information Set field, as shown in Table 2 below. The Presence Bitmap Size field indicates the size of the Link / TID / AC Information Presence Bitmap.

[0100] The Link / TID / AC Information Presence Bitmap field indicates whether there is further information about the buffered BUs in the Link / TID / AC information and is set for non-AP MLDs. The Link / TID / AC Information Set field conveys further information about the buffered BUs for each non-AP MLD.

[0101] According to the present disclosure, assuming that different AID spaces are reserved for allocating AIDs to legacy STAs (11n, 11ac, 11ax STAs) and for allocating AIDs to EHT devices (non-MLD EHT non-AP STAs and non-AP MLD), a separate TIM element (e.g., the existing baseline TIM element) can be used solely to signal buffered BUs for legacy STAs, while a new Multi-link TIM bitmap is included in the Multi-link TIM element solely to signal buffered BUs for EHT devices. The AIDs used to indicate group address BUs (e.g., AID 0, NonTxBSS ID, or the AID space of the AP MLD) are overlapped in both the TIM bitmap for legacy STAs and the Multi-link TIM bitmap for EHT devices. [Table 2]

[0102] 25 shows an example TIM bitmap 2500, an example multilink TIM bitmap 2510, an example AC information presence bitmap, and an example AC information bitmap set in a beacon / TIM frame. In this example, 1020 consecutive AIDs (out of a maximum of 2008) are used by the AP MLD. 510 consecutive AIDs (1-510) are reserved for legacy STAs, and the remaining AIDs (511-1020) are used for EHT devices. Thus, TIM bitmap 2500 is dedicated to indicating buffered BUs for legacy devices (in this case Legacy 1 and Legacy 2, assigned to AIDs 34 and 76, respectively), and multilink TIM bitmap 2510 is dedicated to indicating buffered BUs for EHT devices such as MLD 1, MLD 2, non-MLD EHT STA 1, MLD 3, and single-link MLD 4, assigned to AIDs 512, 528, 535, 557, and 577, respectively. The AID used to indicate group address BUs (AID 0 in this case) is duplicated in the multilink TIM bitmap, as shown by 2505.

[0103] Legacy STAs only need to decode TIM bitmap 2500, while EHT STAs only need to decode Multilink TIM bitmap 2510. In the Multilink bitmap, the bit immediately following the overlapping bit(s) 2505 used to indicate group / broadcast addressed frames corresponds to the first AID in the AID space reserved for EHT devices. To avoid bit overlap in the TIM bitmap, different AID spaces can be reserved for allocating AIDs to legacy STAs and for allocating AIDs to EHT devices.

[0104] As a variation, all non-MLD STAs can be assigned AIDs from the legacy STA AID space and the baseline TIM can be used to indicate buffered BUs for non-MLD STAs. Non-MLD STAs refer to legacy STAs and EHT STAs that do not belong to MLD.

[0105] As a further variation, the single-link MLD can be assigned AIDs from the legacy STA AID space, so that the legacy STA AID space is reserved exclusively for all EHT devices operating on a single link, not just legacy STAs, and the buffered BUs for the single-link MLD can also be indicated using the baseline TIM. In this case, the multilink TIM bitmap is used exclusively to indicate the buffered BUs for the non-AP MLD.

[0106] AC information present bitmap 2502 contains one bit for every bit set to 1 in multilink TIM bitmap 2510, in the same order as multilink TIM bitmap 2510, so AC information present bitmap 2502 has a total size of 5 bits. AC information bitmap set 2504 contains one AC information bitmap for every bit set to 1 in AC information present bitmap 2502, in the same order as AC information present bitmap 2502. Each AC information bitmap contains four bits corresponding to four ACs. In this case, the second and fourth bits corresponding to MLD 2 and MLD 3 in AC information present bitmap 2502 are set to 1, so the AC information bitmap set has a size of 8 bits. In this case, the total overhead for link / TID / AC information using the individual TIM elements for the EHT device, i.e., AC information present bitmap 2502 (5 bits) and AC information bitmap set 2504 (8 bits), is 13 bits.

[0107] 26 shows an example format of a Multi-link TIM element 2600 containing a Multi-link TIM bitmap. The Multi-link TIM 2600 includes an Element field, a Length field, an Element ID Extension field, a Multi-link Control field containing a Type field set to "Multi-link TIM" and a Presence Bitmap field, a Common Info field, and a Link Info field.

[0108] The Presence Bitmap field of the Multi-link Control field further includes a Starting AID Present field, a Multi-link TIM Information Present field, and a Presence Bitmap Size Present field, which are used to indicate the presence of the Starting AID field, the Multi-link TIM Information field, and the Presence Bitmap Size field of the Common Info field. The Common Info field further includes a Link / TID / AC Information Type field, a Starting AID field, a Multi-link TIM Information field, and a Presence Bitmap Size field. The Link Info field further includes a Link / TID / AC Information Presence Bitmap Present field, a Link / TID / AC Information Presence Bitmap field, and a Link / TID / AC Information Set field. The Multi-Link TIM Information field further includes a Bitmap Control field, a Bitmap Length field, and a Multi-link TIM Bitmap field.The Bitmap Control field has the same function as the Bitmap Control field in the legacy TIM element described and illustrated in Figure 24. The Bitmap Length field indicates the length of the multi-link bitmap in octets. The Multi-Link TIM Bitmap field indicates the buffered BUs for EHT devices or non-AP MLDs only. The Link / TID / AC Information Type field indicates what kind of information is conveyed in the Link / TID / AC Information Set field, similar to Table 2 above. The Link / TID / AC Information Presence Bitmap field indicates whether there is further information about the buffered BUs in the Link / TID / AC information and is set for non-AP MLDs. The Link / TID / AC Information Set field conveys further information about the buffered BUs for each non-AP MLD.

[0109] 27 illustrates an exemplary configuration of a communication device 2700 and three communication units 2712, 2722, and 2732 belonging to the communication device 2700. The communication device 2700 is implemented as an AP MLD, and each of the communication units 2712, 2722, and 2732 may be implemented as an AP configured to support a multilink traffic indication map according to various embodiments of the present disclosure. The communication device 2700 includes a multi-TIM element generator 2702 configured to perform multilink traffic indication mapping according to the above-described embodiments, such as generating a Multi-link TIM element and a presence bitmap using a Starting AID field. The Multi-link TIM element includes a partial virtual bitmap (PVM) indicating the presence of one or more buffered units for an external communication device / device associated with the communication device, and the presence bitmap indicates whether additional information (e.g., link / TID / AC information) related to one or more BUs for the associated external communication device / device is present.

[0110] The communication device 2700 comprises a storage module that stores its MLD MAC MLD address 2701. The communication device 2700 further comprises a MAC SAP 2740 that is used to communicate with the Internet layer and / or DS. Each of the communication units 2712, 2722, 2732 belonging to the communication device provides links 2718, 2728, 2738 that are associated with and capable of transmitting to another external communication unit / device and / or DS (e.g., transmitting a frame including a Multi-link TIM element and a presence bitmap using a start AID-related field associated with the start AID) or receiving another signal from another external communication unit / device and / or DS. Each of the participating communication devices 2712, 2722, 2732 includes a MAC layer 2714, 2724, 2734 and a PHY (physical) layer 2716, 2726, 2736, which connects to a radio transmitter, radio receiver, and antenna used to send / receive signals to / from another communication device / device via a corresponding link 2718, 2728, 2738. In one embodiment, the MAC layer includes a storage module that stores its AP MAC address 2715, 2725, 2735, and an optional AP MAC SAP for communicating directly with the Internet layer for traffic to / from legacy STAs.

[0111] 28 illustrates an exemplary configuration of a communication device 2800 and three communication units 2812, 2822, and 2832 belonging to the communication device 2800. The communication device 2800 is implemented as a non-AP MLD, and each of the communication units 2812, 2822, and 2832 may be implemented as a STA configured to support multilink traffic indication mapping according to various embodiments of the present disclosure. The communication device 2800 further includes a multi-TIM element parser 2802 configured to perform multilink traffic indication mapping according to the above-described embodiments, such as receiving and processing a Multi-link TIM element and a presence bitmap using a Starting AID field. The Multi-link TIM element includes a partial virtual bitmap (PVM) indicating the presence of one or more buffered units for the communication device 2700, and the presence bitmap indicates whether additional information (e.g., link / TID / AC information) related to one or more BUs for the communication device 2800 is present.

[0112] The communication device 2800 includes a storage module for storing its MLD MAC MLD address 2801. The communication device 2800 further includes a MAC SAP 2840 used for communicating with the Internet layer and / or DS. Each of the communication units 2812, 2822, 2832 belonging to the communication device provides a link 2818, 2828, 2838, which is associated with and capable of transmitting / receiving other signals from another external communication unit / device and / or DS. Each of the communication units 2812, 2822, 2832 includes a MAC layer 2814, 2824, 2834 and a PHY (physical) layer 2816, 2826, 2836, which connects to a radio transmitter, radio receiver, and antenna used for transmitting / receiving signals to / from another communication unit / device via the corresponding link 2818, 2828, 2838. In one embodiment, the MAC layer includes a storage module that stores its STA MAC addresses 2815, 2825, 2835, and an optional STA MAC SAP for communicating directly with the Internet layer for traffic to and from legacy APs / STAs.

[0113] The present disclosure can be realized by software, hardware, or software cooperating with hardware. Each functional block used in the above-described embodiments can be realized, in part or in whole, by an LSI (large-scale integrated circuit) such as an integrated circuit. Each process described in each embodiment can be controlled, in part or in whole, by the same LSI or a combination of LSIs. The LSI may be formed as an individual chip, or a single chip may be formed to include some or all of the functional blocks. The LSI may include a data input / output unit coupled to it. The LSI referred to here may be referred to as an IC, system LSI, super LSI, or ultra LSI depending on the level of integration. However, the technology for implementing an integrated circuit is not limited to LSI, and may be realized using dedicated circuits, general-purpose processors, or special-purpose processors. Furthermore, a field programmable gate array (FPGA), which can be programmed after the LSI is manufactured, or a reconfigurable processor, which allows the connections and settings of circuit cells arranged within the LSI to be changed, may also be used. The present disclosure can be realized as digital processing or analog processing. If future integrated circuit technology replaces LSI due to advances in semiconductor technology and other derivative technologies, it may be possible to integrate functional blocks using that future integrated circuit technology. Biotechnology can also be applied.

[0114] The present disclosure may be implemented by any type of apparatus, device, or system having communication capabilities, referred to as a communication device.

[0115] Some non-limiting examples of such communication devices include phones (e.g., cellular phones, smartphones), tablets, personal computers (PCs) (e.g., laptops, desktops, netbooks), cameras (e.g., digital still / video cameras), digital players (digital audio / video players), wearable devices (e.g., wearable cameras, smart watches, tracking devices), gaming consoles, e-readers, telemedicine / telehealth equipment, vehicles (e.g., automobiles, airplanes, ships) that provide communication capabilities, and various combinations thereof.

[0116] The communication devices are not limited to portable or mobile devices, but may also include any type of apparatus, device, or system that is non-portable or stationary, such as smart home devices (e.g., appliances, lights, smart meters, control panels), vending machines, and any other "thing" in an "Internet of Things" (IoT) network.

[0117] Communications can include, for example, exchanging data through cellular systems, wireless LAN systems, satellite systems, and various combinations thereof.

[0118] The communications device may include devices such as controllers and sensors coupled to the communications device that perform the communications functions described in this disclosure. For example, the communications device may include a controller or sensor that generates control or data signals used by the communications device to perform the communications functions of the communications device.

[0119] The communications device may further include infrastructure facilities, such as base stations, access points, and any other apparatus, device, or system that communicate with or control apparatuses such as the apparatuses in the non-limiting examples above.

[0120] A non-limiting example of a station may be a station included in a first plurality of stations belonging to a multi-link station logical entity (i.e., MLD, etc.), where as part of the first plurality of stations belonging to the multi-link station logical entity, the stations of the first plurality of stations share a common Medium Access Control (MAC) data service interface to upper layers, and the common MAC data service interface is associated with a common MAC address or traffic identifier (TID).

[0121] It can therefore be seen that embodiments of the present disclosure provide communication devices and methods that operate on multiple links to fully realize the throughput gains of multi-link communications, particularly in multi-link secure retransmission.

[0122] While the foregoing detailed description of the present embodiments has presented exemplary embodiments, it should be understood that numerous variations exist. Furthermore, it should be understood that the exemplary embodiments are examples and are not intended to limit the scope, applicability, operation, or configuration of the present disclosure in any way. Rather, the foregoing detailed description provides those skilled in the art with convenient guidance for implementing the exemplary embodiments. It should be understood that various changes can be made in the function and organization of the steps and methods of operation described in the exemplary embodiments, and in the modules and structure of the devices described in the exemplary embodiments, without departing from the scope of the subject matter set forth in the appended claims.

Claims

1. A non-access point (AP) multi-link device (MLD) including a plurality of stations (STAs), a receiving unit that receives a frame including a traffic indication map (TIM) element and a start AID (Associated Identifier) ​​field, the TIM element including a partial virtual bitmap (PVM) indicating the presence or absence of one or more buffered units (BUs) for each of a plurality of non-AP MLDs including the non-AP MLD, and the start AID field indicating the smallest AID among the AIDs corresponding to the plurality of non-AP MLDs for which a link information bitmap indicating the presence or absence of traffic for each link exists; a circuit for determining, based on the starting AID field and the link information bitmap, a link on which the one or more BUs for the circuit are present; Non-AP MLD with.

2. The PVM includes a first portion associated with AIDs assigned to a plurality of legacy STAs and a second portion associated with AIDs assigned to the plurality of non-AP MLDs, and a starting position of the second portion is specified by a starting AID indicated by the starting AID field. The non-AP MLD of claim 1.

3. The frame is a beacon frame. The non-AP MLD of claim 1.

4. A PVM indicating the presence or absence of one or more BUs for each of a plurality of non-AP STAs belonging to each non-AP MLD is included in a TIM element different from the TIM element; The non-AP MLD of claim 1.

5. A communication method for a non-access point (AP) multi-link device (MLD) including multiple stations (STAs), comprising: receiving a frame including a Traffic Indication Map (TIM) element and a Start Associated Identifier (AID) field, wherein the TIM element includes a Partial Virtual Bitmap (PVM) indicating the presence or absence of one or more buffered units (BUs) for each of a plurality of non-AP MLDs including the non-AP MLD, and the Start AID field indicates the smallest AID among the AIDs corresponding to the plurality of non-AP MLDs for which a link information bitmap indicating the presence or absence of traffic for each link exists; determining, based on the starting AID field and the link information bitmap, the link on which the one or more BUs for itself exist; A communication method including:

6. The PVM includes a first portion associated with AIDs assigned to a plurality of legacy STAs and a second portion associated with AIDs assigned to the plurality of non-AP MLDs, and a starting position of the second portion is specified by a starting AID indicated by the starting AID field. The communication method according to claim 5.

7. The frame is a beacon frame. The communication method according to claim 5.

8. A PVM indicating the presence or absence of one or more BUs for each of a plurality of non-AP STAs belonging to each non-AP MLD is included in a TIM element different from the TIM element; The communication method according to claim 5.

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