KR101368023B1 - Method and system for improving responsiveness in exchanging frames in a wireless local area network - Google Patents

Abstract

A method and system for improving responsiveness in exchanging management and control frames in a local area network (WLAN). The initiator sends a frame (action, management, control or data frame) to the responder. In the case of correctly receiving this frame, the responder sends a response frame to the initiator instead of directly sending an acknowledgment (ACK) packet. The responder preferably accesses the wireless medium and transmits the response frame in short inter-frame spacing (SIFS). With this scheme, the long delay associated with wireless media competing to transmit a response frame can be avoided, which significantly improves the responsiveness and timeliness of the feedback mechanism. The response frame is piggybacked on another packet or integrated with another packet.

Description

TECHNICAL FIELD [0001] The present invention relates to a method and system for improving responsiveness at the time of frame exchange in a wireless local area network (WLAN)

The present invention relates to a wireless local area network (WLAN). More particularly, the present invention relates to a method and system for improving responsiveness in managing, controlling, or exchanging data frames in a WLAN.

In an IEEE 802.11 WLAN, an access point (AP) or a station (STA) performs management functions using a management frame. An example of management frames are related requests, related responses, re-related requests, re-related responses, probe requests, and probe request frames.

IEEE 802.11e uses the new management frame to extend the IEEE 802.11 standard. Some of these new management frames are referred to as action frames. The action frame is used to perform arbitrary functions such as quality of service (QoS) traffic stream setting, direct link setting, block ACK setting, and the like. Examples of action frames include an Add Traffic Stream (ADDTS) request, an ADDTS response, a Direct Link Setup (DLS) request, a DLS response, an ADDBA (Add Block Acknowledgment) request, an ADDBA response, a Delete Block ACK (DELBA)

In general, the IEEE 802.11n extension standard has been proposed to achieve higher throughput (HT). In the IEEE 802.11n proposal, new action frames are introduced to provide transmission mode and channel information feedback. By the transmission mode feedback, the receiving station notifies the transmitting station of the desired mode for the current channel condition. The specific mode selection is determined by the receiving station. The transmitting station may or may not use the specific mode depending on its capacity. The receiving station may also refuse to provide the desired mode. The channel information feedback provides a mechanism for the transmitting station to detect the correct channel seen at the receiving station. This information may be used as part of calibration, or as direct channel feedback, for a system that assumes channel correlation. The receiving station may provide a complete channel estimate or a null response value. An example of an IEEE 802.11n action frame is a mode request, a mode response, a multiple-input multiple-output (MIMO) channel request, and a MIMO channel response frame.

A management frame (including an action frame) may be broadcast or multicast to a plurality of responders (e.g., via a beacon frame), or alternatively may be a specific (single) responder (e.g., ADDBA Request, an ADDBA response, a mode request, a mode response, a MIMO channel request, and a MIMO channel response). In the event that ancillary and action frames are unicast to a specific responder, the IEEE 802.11 standard requires a responder to acknowledge receipt of such a frame by sending an ACK packet. On the other hand, if the management or action frame is broadcast or multicast to multiple responders, the IEEE 802.11 standard does not require a responder to acknowledge receipt of such a frame.

FIG. 1 is a signaling diagram of a prior art process 100 for exchanging management frames or action frames between an initiator 102 and a responder 104. The initiator 102 accesses the wireless medium which requires some delay corresponding to contention or access delays under the IEEE 802.11 standard and sends an action frame (e.g., a mode request frame) to the responder 104 (Step 112). In response to receiving the action frame correctly, the responder 104 accesses the wireless medium, which also includes some delay (e.g., a delay corresponding to short inter-frame spacing (SIFS) And sends an ACK packet to the initiator (step 114). Responder 104 may then send an action frame (e. G., A mode response frame) containing the data requested by initiator 102 and then request some delay due to contention or access delays Accesses the wireless medium again and sends this action frame to the initiator (step 116). At this time, the delay may be substantially longer, since it is not possible for other stations to exchange packets at that time and the respondent 104 can not access the desired wireless medium. The initiator 102 accesses a wireless medium that requires some delay (typically a time period corresponding to SIFS) and sends an ACK packet to the responder 104 (Step 118).

In the prior art process 100, after the responder 104 first transmits an ACK packet (step 114), a contention or access delay must be generated in step 116 to access the wireless medium and transmit the response frame. This slow management or action frame response may degrade the performance of the WLAN because it may or may not be effective at the time the information is delivered. For example, because of the transmission mode feedback, respondent 104 specifies or displays initiator transmission related information including data rate, modulation and coding scheme (MCS), number of spatial streams in MIMO, and guard interval, Information should be exchanged as soon as possible. However, under the prior art scheme, the exchange of such information may be substantially delayed.

Therefore, a new mechanism for exchanging management or action frames within a very short time period is required.

The present invention relates to a method and system for improving responsiveness in the exchange of management and control frames in a WLAN. The initiator sends a frame (action, management, control or data frame) to the responder. In the case of correctly receiving this frame, the responder sends a response frame to the initiator instead of directly sending an ACK packet. The responder preferably accesses the wireless medium and transmits a response frame within the SIFS. In this manner, the long delay associated with competing in the wireless medium for transmitting a response frame can be avoided, thereby significantly improving the responsiveness and timeliness of the feedback mechanism. The response frame may be piggybacked on another packet or integrated with another packet.

As described above, the present invention can provide a method and system for improving responsiveness in the case of exchanging management and control frames in a WLAN.

Figure 1 is a prior art signaling diagram for exchanging management frames or action frames between an initiator and a responder.
2 is a signaling diagram for exchanging a management or action frame between an initiator and a responder in accordance with the present invention;
Figures 3 and 4 illustrate an example of an integrated medium access control layer protocol data unit (A-MPDU) with an ACK policy designated as a management medium access control (MAC) layer protocol data unit (MMPDU) ) To illustrate an exemplary process for exchanging packets between an initiator and a responder.
5 and 6 illustrate an example of exchanging packets between an initiator and a responder using a reduced inter-frame spacing (RIFS) with an ACK policy designated as No-ACK for the MMPDU according to the present invention Fig.

Hereinafter, the terms "initiator" and "responder" refer to a user equipment (UE), a wireless transmit / receive unit (WTRU), a mobile station, a fixed or mobile subscriber station, a pager, , A site controller, an access point, or any other type of device capable of operating in a wireless environment.

The features of the present invention may be incorporated into an integrated circuit (IC) or may be configured in a circuit having a plurality of interconnecting components.

Figure 2 is a signaling diagram of a process 200 for exchanging action frames between an initiator 202 (also known as a sender) and a responder 204 (also known as a receiver), in accordance with the present invention. Initiator 202 is a communications entity with a transmit opportunity (TXOP) and is a frame exchange sequence comprising an aggregate physical layer protocol data unit (A-PPDU) The first frame is transmitted. Responder 204 is a communication entity that responds to initiator 202 in a frame exchange sequence that includes an A-PPDU and an aggregate control frame. Initiator 202 sends an action frame (typically a request frame such as a mode request frame) to responder 202 (step 212). If the action frame is received correctly, instead of sending an ACK packet directly, the responder 204 transmits a responsive action frame (e.g., a mode response frame) (step 214). Hereinafter, the present invention will be described with reference to an action frame. However, the present invention is equally applicable to any type of frame, such as a management frame, a control frame, a data frame, and the like. The request frame and the response frame may be other types of frames.

Responder 204 preferably accesses the wireless medium and transmits a response action frame in a time period corresponding to SIFS. The initiator 202 then preferably transmits an ACK frame after a short delay corresponding to that SIFS. According to the present invention, the long delay associated with contention for wireless medium in step 116 of FIG. 1 can be avoided, thereby greatly improving the responsiveness and timeliness of the feedback mechanism.

Alternatively, at step 214, the response action frame may be piggybacked on an ACK frame, another management or control frame, or a data packet, or may be piggybacked on its ACK frame, another management or control frame, . In the case where the ACK frame is piggybacked or integrated, the ACK packet transmitted in response to the initiating action frame (i.e., mode request frame) is not removed, but is transmitted along with another frame.

The signaling mechanism of the present invention may be performed by default or in accordance with a common procedure established for both the initiator 202 and the responder 204. In this case, additional fields are included in the action frame (including the management frame, control frame, data frame, etc.) to indicate the desired signaling mechanism. For example, the initiator 202 may transmit a request frame (e.g., a mode request frame, a MIMO channel request frame), an MCS request (MRQ) frame, a channel status information (CSI) request frame, (TRQ) frame, etc.) and sets a new field in the request frame that indicates how the respondent 204 is trying to respond to the request frame.

The new fields include, but are not limited to, an ACK policy field, a request identity number field, a response time policy field, and an integration policy field. The ACK policy field indicates whether the responder 204 needs to send an ACK packet.

The request identity number field contains the request identity number. The response frame uses a similar request identity number field having a value corresponding to the request identity number in the request frame. Alternatively, the request identity number field in the response frame may be set to a specific value when the response frame is transmitted as often as possible, as will be described in detail later.

The response time policy field indicates whether the responder 204 has responded to the initiator 202 immediately (i.e., SIFS) or within a certain time period that is longer than the short delay, or the number of times that the responder 204 selects Or not).

The aggregate policy field may be used by the responder 204 to send a response frame piggybacked on another packet or to send an ACK packet, management or control packet, data packet, or any other type of packet, Integrated. The plurality of management frames may be integrated in the packet. A block ACK (BA) may be used if a simple ACK is used and one or more MMPDUs are transmitted as part of an aggregate, if the MMPDU is transmitted alone (i.e., not part of an aggregate).

When the ACK policy is selected to include the ACK for the response frame, the following methods may be applied. The MMPDU is assigned a sequence number (SN) by the initiator 202 using a single counter, which is not unique to the responder, and is also used for the -QoS data subtype frames used in the broadcast / multicast frame do. According to the present invention, the management frames may be sequenced using a new separate SN counter unique to the responder. Alternatively, the management frames may be sequenced using the same SN counter as the SN counter of the data incorporating the management frames. Since the gap at the received SN can not be used to identify explicitly lost frames by this responder 204, another method uses the same IEEE 802.11e method of assigning the SN to management frames, and the responder 204 May not rearrange the management frames. Initiator 202 is only required to store a copy of these persistent frames specified in the ACK policy field until management frames are acknowledged or their lifetime expires.

For a block ACK request (BAR) for a management frame, the ACK policy field of the new MMPDU may be described as a BAR. Alternatively, a separate BAR MAC protocol data unit (MPDU) for the frames involved may be transmitted as part of the aggregate (i.e., the aggregator includes a BAR frame for the data frame and a BAR frame for the management frame) have. Alternatively, the original BAR MPDU format may be extended to include additional portions for management frames (i. E., The aggregator may include one bar with a portion for the management frame and one for the data frame, ) Frame).

For a BA packet, a separate BA MPDU for the management frame may be sent as this part of the aggregator (i.e., the aggregator includes a BA packet for the data frame and a BA packet for the management frame). Alternatively, the conventional BA MPDU format may be extended to include additional portions for acknowledging management frames.

For the formats of BA and BAR packets supporting the management frame, the BA and BAR packets used in the management frames may be made the same as or similar to the conventional format, and may be explicitly identified . The BA and BAR may use the concept of an initiation sequence number (SSN) followed by a bitmap. When the bit position n of the BA bitmap is set to 1, it confirms receipt of the MPDU having the same sequence control value as BA SSN + n. If the bit position n of the BA bitmap is set to 0, it indicates that the MPDU having the same MPDU sequence control value as (BA SSN + n) has not been successfully received. Typically, the unified management frames have an incremental SN. (Integrate) a plurality of BAs when the unified management frames have a large gap in the SN (e.g., merging retransmitted frames and new frames), and each BA may use a different management frame Or frames. For example, if the bitmap has a predetermined maximum size (e.g., 16 bits) and the combined management frames have a sequence number that is more than 15 different, they can not be acknowledged in the same bitmap, Another BA frame is required. The BA and BAR may simply list the SN for each associated management frame.

An MRQ frame, an MCS feedback (MFB) frame and a training request (TRQ) frame containing new fields are described here by way of example. However, any other management, control, or data frame may include new fields that improve the responsiveness of the packet exchange.

The MRQ frame is a management frame of category HT. The MRQ frame is used to request MCS feedback from the responder 204. The MRQ frame includes one or more ACK policy fields, a request identity number field, a response time policy field, and an integrated format field in addition to the MCS request field, as shown in Table 1. The ACK policy field is set to either "No-ACK" (ie, request a direct MFB frame response) or "ACK" (ie, request an ACK packet). The request identity number field is set to the request identity number when one MFB packet is expected, or to '0' when the MFB packet is transmitted as often as possible. The response time policy field is set to "immediate" (i.e., SIFS), "delayed" If the response time policy is set to "immediate ", the responder 204 tries to send the MFB frame immediately (i.e., within SIFS). If the response time policy is set to "delayed ", the responder 204 tries to transmit the MFB frame at a specific delay time. The integrated format field may be set to "Integrated MAC Protocol Data Unit" (A-MPDU), "RIFS-PPDU" or "No-Aggregation". If the unified format field is set to "A-MPDU ", then responder 204 and initiator 202 will attempt to transmit an A-MPDU. If the unified format field is set to "RIFS-PPDU ", responder 204 and initiator 202 may attempt to transmit multiple MPDUs using RIFS, but may also generate A-MPDUs. If the unified format field is set to non-unified, the responder 204 and initiator 202 do not attempt to integrate the MFB frame. Alternatively, if the aggregate format field is not included in the MRQ frame or the MFB frame, then the responder 204 or initiator 202 will itself be determined by this aggregate format field without being directed by another party Integration can also be performed. The MCS request indicates the requested feedback type.

Body Field Order Frame body field information for MCS request frame One ACK policy 2 Request identity number 3 Request time policy 4 Integrated format 5 MCS Request

The MFB frame is a management frame of category HT. The MFB frame is transmitted in response to the MRQ frame or independently. The MFB frame includes at least one of an ACK policy field, a request identity number field, a response time policy field, and an integrated format field in addition to the MFB field as shown in Table 2. The ACK policy field is set to either "No-ACK" or "ACK". The Request Identity Number field is set to the corresponding request number from the MRQ frame if requested or to '0' if the MFB frame is transmitted as often as possible or not requested. The response time policy field is set to "immediate" (i.e., SIFS), "delayed" The integrated format field may be set to "A-MPDU", "RIFS-PPDU", or "No-Aggregation". The operations of the ACK policy field, the request identity number field, the response time policy field, and the unified format field are the same as those of the MRQ frame, and thus are not repeated here for the sake of simplicity. The MCS feedback field contains an MCS response.

Body Field Order Frame body field information for MCS feedback frame One ACK policy 2 Request identity number 3 Response time policy 4 Integrated format 5 MCS Feedback

The TRQ frame is a management frame of the category HT. The TRQ frame requests that the next transmission by the responder 204 be a sounding PPDU with a particular physical layer attribute. The TRQ frame includes at least one of an ACK policy field, a request identity number field, a response time policy field, and an integrated format field in addition to a channel sounding parameter field as shown in Table 3. The ACK policy field is set to either "No-ACK" or "ACK ". The request identity number field is set to the number of requests based on the training procedure. The response time policy field is set to "immediate" (SIFS), "delayed" The integrated format field is set to "A-MPDU", "RIFS-PPDU", or "No-Aggregation". The operations of the ACK policy field, the request identity number field, the request time policy field, and the unified format field are the same as those of the MRQ frame, and thus are not repeated here for the sake of simplicity. The channel sounding parameter field indicates the number and type of HT-long training field (LTF), the number of transmit and receive antennas, and the like.

Field order Frame body field information for a training request (TRQ) frame One ACK policy 2 Request identity number 3 Response time policy 4 Integrated format 5 Channel Sounding Parameters

The new fields (i.e., one or more of the ACK policy field, the request identity number field, the response time policy field, and the unified format field) include a mode request frame, a mode response frame, a MIMO channel request frame, a MIMO channel response frame, A CSI feedback request frame, a calibration start frame, a calibration sounding response frame, a transmit antenna selection sounding request frame, an antenna selection feedback frame, and the like.

The mode request frame and mode response frame are used to exchange the optimal transmission mode for use in high throughput communication. A MIMO channel request frame, a MIMO channel response frame, a CSI feedback request frame, and a CSI feedback response frame are used to exchange CSI between the initiator 202 and the responder 204. A calibration start frame and a calibration sounding response frame are used for calibration purposes to eliminate the difference between the sender and receiver chain of initiator 202 and responder 204. [ The transmit antenna selection sounding request frame and the antenna selection feedback frame are used for antenna selection by the initiator 202 or the responder 204.

Figure 3 shows an exemplary process 300 for exchanging packets between an initiator 302 and a responder 304 using an A-MPDU with an ACK policy designated as No-ACK for an MMPDU according to the present invention. Initiator 302 generates a requeqt-to-send (RTS) frame 312 when there is data to be transmitted to responder 304 and uses this base rate unified PPDU 314 to generate a RTS (312) to the responder (304). Upon receipt of the RTS frame 312, the responder 304 sends a clear-to-send (CTS) frame 316 to the initiator 302 using the base rate unified PPDU 318. After receiving this CTS frame 316, the initiator 302 generates an A-MPDU 320 that includes an MRQ MMPDU 320a, a data MPDU 320b, and a BAR MPDU 320c. The A-MPDU 320 is transmitted using an integrated PPDU (A-PPDU) 322, which is generated based on the basic MIMO and the default MCS.

Since the ACK policy field of the MRQ MMPDU 320a is set to No-ACK, the responder 304 directly transmits the MFB MMPDU 314a without ACK transmission to acknowledge receipt of the MRQ MMPDU 320a. Responder 304 generates A-MPDU 324 including MFB MMPDU 324a and BA 324b to acknowledge receipt of data MPDU 320b and uses A-PPDU 326 to send A -MPDU (324).

The initiator 302 receives the MFB MMPDU 324a and selects the optimized MCS according to the MCS feedback included in the MFB MMPDU 324a. Initiator 302 generates another A-MPDU 328 including data MPDU 328a and BAR MPDU 328b and uses an A-PPDU 320 with an optimized rate based on MCS feedback And transmits it. Responder 304 then sends BA 332 using non-aggregated PPDU 334 in response to BAR MPDU 328b. After successful transmission of the data, the initiator 302 transmits the CF-Poll END frame 336 to release the TXOP using the base rate unified PPDU 338.

4 illustrates another exemplary process 400 for exchanging packets between an initiator 402 and a responder 404 using an A-MPDU with an ACK policy designated as No-ACK for the MMPDU according to the present invention. . Initiator 4022 may generate an RTS frame 412 if there is data to send to responder 404 and send this RTS frame 412 to responder 404 using the base rate non-aggregated PPDU 414 . Upon receipt of the RTS frame 412, the responder 404 transmits the CTS frame 416 to the initiator 402 using the base rate non-aggregated PPDU 418. After receiving the CTS frame 416, the initiator 402 sends an A-MPDU 420 containing the TRQ MMPDU 420a, the MRQ MMPDU 420b, the data MPDU 420c and the BAR MPDU 420d . The A-MPDU 420 is transmitted using the integrated PPDU 422, which is generated based on the default MIMO and the default MCS.

The ACK policy field of the TRQ MMPDU 420a and the MRQ MMPDU 420b is set to No-ACK so that the responder 404 can directly receive the MRQ MMPDU 420b without sending another ACK, Lt; / RTI > The responder 404 generates an A-MPDU 424 that includes the MFB MMPDU 424a and the BA 424b and uses the sounding A-PPDU 426 as requested by the TRQ MMPDU 420a And transmits it.

The initiator 402 then receives the sounding PPDU 426 and estimates the channel selection information (CSI) based on the sounding PPDU 426. The estimated CSI is used to set the MIMO parameter at the time of transmission of the next packet. The initiator 402 also receives the MFB MMPDU 424a and selects the optimized MCS according to the MFB frame included in the MFB MMPDU 424a. Initiator 402 generates another A-MPDU 428 including TRQ MMPDU 428a, MRQ MMPDU 428b, data MPDU 428c and BAR MPDU 428d, and A-PPDU 430, And transmits the A-MPDU 428 using the A-MPDU 428. The A-PPDU 430 is generated based on the optimized MCS and MIMO parameters according to CSI and MFB. Responder 404 receives A-MPDU 428 and generates another A-MPDU 432 that includes MFB MMPDU 432a and BA 432b and uses another sounding PPDU 434 And transmits it. The initiator 402 receives the sounding A-PPDU 434, estimates the CSI, and selects the MCS based on the MFB. Initiator 402 generates another A-MPDU 436 that includes data MPDU 436a and BAR MPDU 436b and transmits it using A-PPDU 438. [ The A-PPDU is generated based on the MCS and MIMO parameters that are updated according to the second CSI and the MFB. Responder 404 then sends BA 440 in response to BAR MPDU 436b using non-aggregated PPDU 442. [ After successful transmission of the data, the initiator 402 transmits the CF-Poll End frame 444 to release the TXOP using the non-aggregated PPDU 446 at the base rate.

FIG. 5 shows an exemplary process 500 for exchanging packets between an initiator 502 and a responder 504 using RIFS with an ACK policy designated as No-ACK for the MMPDU according to the present invention. Initiator 502 generates an RTS frame 512 when there is data to send to responder 504 and sends this RFS frame 512 to responder 504 using a non-aggregated PPDU 514 at base rate . Upon receipt of the RTS frame 512, the responder 504 transmits the MRQ MMPDU 520 using the non-aggregated PPDU 522 at the base rate. Without releasing the TXOP, the initiator 502 also generates an A-MPDU 524 that includes the data MPDU 524a and the BAR MPDU 524b, and the A-MPDU 524 of the PPDU 522 using the A- And transmits the A-MPDU 524 after the RIFS from the transmission.

After receiving the MRQ MMPDU 520, the responder 504 directly sets the MFB MMPDU 528 without sending an ACK because it is set to the ACK policy field No-ACK of the MRQ MMPDU 520. Without releasing the TXOP, the responder 504 may generate a BA frame 532 to acknowledge receipt of the data MPDU 524a and may use the non-aggregated PPDU 534 to decode the data from the transmission of the PPDU 530 And transmits BA 532 after RIFS.

The initiator 502 receives the MFB MMPDU 528 and selects the optimized MCS according to the MFB included in the MFB MMPDU 528. [ Initiator 502 generates an A-MPDU 536 including a data MPDU 536a and a BAR MPDU 536b and generates an A-PPDU 536 based on the MCS optimized based on the MFB and the basic MIMO parameter 538 to the A-MPDU 536. Responder 504 then sends BA 540 to acknowledge receipt of data MPDU 536a using non-aggregated PPDU 542. [ After successful transmission of data, the initiator 504 transmits a CF-Poll END frame to release the TXOP using the non-aggregated PPDU 546 at the base rate.

FIG. 6 shows another exemplary process 600 for exchanging packets between an initiator 602 and a responder 604 using RIFS with an ACK policy designated as No-ACK for the MMPDU according to the present invention. Initiator 602 generates an RTS frame 612 if there is data to send to responder 604 and sends this RFS frame 612 to responder 604 using non-aggregated PPDU 614 at base rate . Upon receipt of the RTS frame 612, the responder 604 transmits the CTS frame 616 to the initiator 602 using the base rate non-aggregated PPDU 618. After receiving the CTS frame 616, the initiator 602 generates a TRQ MMPDU 620 and transmits this TRQ MMPDU 620 using a non-aggregated PPDU 622. In the same TXOP, the initiator 602 also generates an MRQ MMPDU 624 and transmits the MRQ MMPDU 624 after the RIFS from the transmission of the PPDU 622 using the non-integrated PPDU 626. In addition, in the same TXOP, the initiator 602 generates an A-MPDU 628 that includes a data MPDU 628a and a BAR MPDU 628b, and uses the A-PPDU 630 to generate the A- 628 < / RTI > This A-PPDU 630 is generated based on the basic MIMO parameter and the default MCS.

The responder 604 receives the TRQ MMPDU 620 and the MRQ MMPDU 624 and generates the MFB MMPDU 632 and sends it via the sounding A-PPDU 634, as requested by the TRQ MMPDU 620, send. Since the ACK policy field of the TRQ MMPDU 620 and the MRQ MMPDU 624 is set to No-ACK, the responder 604 transmits a separate ACK to acknowledge receipt of the TRQ MMPDU 620 and the MRQ MMPDU 624 The MFB MMPDU 632 directly transmits the data to the MFB MMPDU 632.

In the same TXOP, responder 604 also generates BA 636 to acknowledge receipt of data MPDU 628b, and after RIFS from transmission of PPDU 634 using non-aggregated PPDU 638 BA 636. < / RTI >

The initiator 602 then receives the sounding PPDUs 634 and estimates the CSI based on the sounding PPDUs 634. The estimated CSI is used to set the MIMO parameters at the time of transmission of the next packet. The initiator 602 also receives the MFB MMPDU 632 and selects the optimized MCS according to the MFB included in the MFB MMPDU 632.

Initiator 602 generates a second TRQ MMPDU 640 and transmits it via A-PPDU 642. In the same TXOP, initiator 602 also generates a second MRQ MMPDU 644 and transmits it after RIFS from transmission of A-PPDU 642 using A-PPDU 646. The initiator 602 also generates an A-MPDU 648 that includes the data MPDU 648a and the BAR MPDU 618b and uses the A-PPDU 650 to generate the PPDU 646 MPDU 648 after the RIFS from the transmission of the A-MPDU 648. The A-PPDUs 642, 646, 650 are generated based on the optimized MCS and MIMO parameters according to CSI and MFB.

The responder 604 receives the second TRQ MMPDU 640 and the second MRQ MMPDU 644 and generates a second MFB MMDPU 652 and uses the second sounding A- And transmits the MMPDU 652. At the same TXOP, responder 604 also generates BA 656 to acknowledge receipt of data MPDU 648 and transmits BA 656 using non-aggregated PPDU 658. [

After receiving the second sounding A-PPDU 654 including this second MFB MMPDU 652, the initiator 602 estimates the CSI and, based on the new MFB included in the MFB MMPDU 652, Select MCS. The initiator 602 generates a third A-MPDU 670 including a data MPDU 670a and a BAR MPDU 670b and generates a third A-MPDU 670 using the A-PPDU 672, And this A-PPDU 672 is generated based on the optimized MCS and MIMO parameters according to the updated CSI and MFB.

Responder 604 receives A-MPDU 670 and sends BA 674 to acknowledge receipt of data MPDU 670a using non-aggregated PPDU 676. After successful transmission of data, the initiator 602 transmits a CF-Poll END frame 678 to release the TXOP using a non-aggregated PPDU 680 at the base rate.

According to another embodiment of the present invention, an action, management or control frame may be prioritized over a data frame. This prioritization may be accomplished explicitly through designated fields in an action, management, or control frame when accessing a wireless medium, or may be accomplished by hardware or software implementations that process actions, management or control frames with higher priority ≪ / RTI > This prioritization scheme may be applied to all action, management or control frames proposed by TGnSync or by WWiSe, particularly for actions and management frames (e.g., mode requests, mode responses, MIMO Channel request and MIMO channel response, MRQ frame, TRQ frame).

Although the features and elements of the present invention have been described in terms of specific combinations in the preferred embodiments, each feature or element may be used alone or in combination with other features and elements of the present invention Or may be used without them.

102, 202: Initiator 104, 204: Respondent

Claims (24)

A method for use in a first station (STA)
The first station requests channel state information (CSI) from a second station, wherein the CSI request is based on the second CSI request based on the CSI request. Indicating that it will be transmitted by the station; And
The first station receiving a CSI response based on the CSI request from the second station, the CSI response including CSI feedback
RTI ID = 0.0 > 1, < / RTI > The method of claim 1, wherein the CSI response is received within a short inter-frame spacing (SIFS) of the CSI request. 2. The method of claim 1, wherein the CSI response is piggybacked on another frame. 2. The method of claim 1, wherein the CSI response is aggregated with another frame. The method of claim 1,
Sending, by the first station, to another station a management action frame including an ACK policy field, the ACK policy field indicating to the other station to acknowledge receipt of the management action frame in a separate ACK frame;
Receiving, by the first station, an ACK frame in response to the management action frame before receiving a second management action frame from the other station;
RTI ID = 0.0 > 1, < / RTI > 2. The method of claim 1, wherein the CSI request comprises a Request Identity Number field for indicating a request identity number. 2. The method of claim 1, wherein the CSI request comprises a response time policy field for indicating whether the CSI response is to be received immediately or within a predetermined time period. Way. 2. The method of claim 1, wherein the CSI request comprises an integrated policy field for indicating whether the CSI response can be merged with at least one other frame. 9. The method of claim 8, wherein the unified policy field indicates that a plurality of packets should be received with reduced inter-frame spacing (RIFS). The method of claim 1, wherein the CSI request comprises a training request and the CSI response is a sounding frame. 2. The method of claim 1, wherein the CSI feedback is used for at least one of transmit beam forming, calibration, and antenna selection. 2. The method of claim 1, wherein the CSI request comprises a modulation and coding scheme (MCS) request, the CSI response comprises MCS feedback,
Wherein the method for use in the first station further comprises generating a next frame based on the MCS feedback. In a station (STA)
Channel state information (CSI) request to a second station, where the CSI request may be sent by the second station based on the CSI request for immediate feedback, aggregated feedback or delayed feedback. Indicating that the transmitter is configured to transmit; And
A receiver configured to receive a CSI response based on the CSI request from the second station, the CSI response including CSI feedback
≪ / RTI > 14. The station of claim 13, wherein the receiver is configured to receive the CSI response within a short inter-frame spacing (SIFS) of the CSI request. 14. The station of claim 13, wherein the receiver is configured to receive the CSI response that is piggybacked on another frame. 14. The station of claim 13, wherein the receiver is configured to receive the CSI response aggregated with another frame. 15. The method of claim 13, wherein the transmitter indicates to another station a management action frame including an ACK policy field, the ACK policy field indicating to the other station to acknowledge receipt of the management action frame in a separate ACK frame. Configured to send,
And the receiver is configured to receive an ACK frame in response to the management action frame before receiving a second management action frame from the other station. 14. The station of claim 13, wherein the transmitter is configured to transmit the CSI request including a request identity number field to indicate a request identity number. 14. The apparatus of claim 13, wherein the transmitter is configured to send the CSI request including a response time policy field to indicate whether the CSI response will be received immediately or within a predetermined time period. station. 14. The station of claim 13, wherein the transmitter is configured to transmit the CSI request including an integration policy field to indicate whether the CSI response can be integrated with another frame. 21. The station of claim 20, wherein the unified policy field indicates that the station should receive multiple packets with reduced inter-frame spacing (RIFS). 14. The station of claim 13, wherein the transmitter is configured to send the CSI request comprising a training request and the receiver is configured to receive a sounding frame as the CSI response. The method of claim 13,
And a processor configured to use the CSI feedback for at least one of transmit beam forming, calibration, and antenna selection. 14. The apparatus of claim 13, wherein the transmitter is configured to send the CSI request including a modulation and coding scheme (MCS) request, and the receiver is configured to receive the CSI response including MCS feedback. And the transmitter is configured to transmit the next frame based on the MCS feedback.

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