CN101401334A

CN101401334A - Symmetric transmit opportunity(txop) truncation

Info

Publication number: CN101401334A
Application number: CNA2007800086655A
Authority: CN
Inventors: 门佐·温汀克
Original assignee: Conexant Systems LLC
Current assignee: Intellectual Ventures I LLC
Priority date: 2006-01-10
Filing date: 2007-01-10
Publication date: 2009-04-01
Anticipated expiration: 2027-01-10
Also published as: CN101401334B

Abstract

Various embodiments of symmetric transmit opportunity (TXOP) truncation (STT) systems and methods are disclosed. One method embodiment, among others, comprises receiving a frame that truncates a TXOP around a first station, and responsive to receiving the frame, sending a second frame that truncates the TXOP around a second station. Others system and method embodiments are disclosed.

Description

Symmetry transmission opportunity (TXOP) is blocked

The cross reference of related application

The application is that the sequence number of submitting to 8 days common unsettled November in 2006 is 11/557,516 name is called the part continuation application (CIP) of the novel application of U.S. utility of " Collision Avoidance Systems and Methods ", the sequence number that this common pending application requires on November 8th, 2005 to submit to is 60/735, the sequence number that 024 name is called " Avoiding EIFS " and submission on January 11st, 2006 is 60/758,595 name is called the U.S. Provisional Application No. of " CF-End Response ", and all these applications all are contained in this to do reference.

The sequence number that the application requires on January 10th, 2006 to submit to is that 60/757,827 name is called the common unsettled U.S. Provisional Application No. of " Symmetric TXOP Truncation ", and it is contained in this to do reference.

Background technology

Technical field

The disclosure relates generally to communication system and method, and more specifically, system and method is avoided in the conflict that relates in the wireless network.

Correlation technique

Communication network occurs in a variety of forms.Noticeable network comprises wired and wireless network.Wherein cable network comprises Local Area Network, DSL network, and cable system (cable network).Wherein wireless network comprises cellular phone network, traditional ground mobile wireless network and satellite transmission network.The general features of these wireless networks is wide area networks.Recently, propose WLAN and wireless home network, and introduced the exploitation of managing the wireless device that is used for these LAN such as the standard of bluetooth and IEEE802.11.

WLAN (wireless local area network) (LAN) generally uses infrared (IR) or radio frequency (RF) communication channel to communicate between portable or mobile computer terminal and access point (AP) or base station.These access points are connected to network infrastructure by the wired or wireless communication channel again, and the described network facilities is joined together to form the LAN that randomly comprises one or more host computer systems with the group of access point.

The logic interconnection that has these portable roaming terminals of polytype communication capacity to host computer such as the wireless protocols support of bluetooth and IEEE802.11.This logic interconnection is based on infrastructure, in this infrastructure, at least some terminals in being located in predetermined scope the time can with AP at least two communicate, each terminal normally with access point in an independent access point carry out related and communicate with it.Based on the loading demand of whole space layout, response time and network, different networking blueprints and communication protocol have been designed so that supervisory communications more effectively.

Ieee standard 802.11 (" 802.11 ") proposes in " WLAN (wireless local area network) medium access control (MAC) and physical layer (PHY) standard ", and can be from IEEE Standards DepartmentPiscataway, and N.J. obtains.The IEEE802.11 standard allows: with 1Mbps, 2Mbps and higher data rate carry out infrared or radio communication; Avoid (CSMA/CA) similarly media interviews technology with csma/conflict; The energy-saving mode that is used for battery powered mobile base station; Seamless roam in whole cellular network; The work of high-throughput; Be designed to eliminate the multiple antenna system of " blind spot "; And with the easy interface of existing network infrastructure.Ieee standard 802.11b expansion supports to reach the data rate of 11Mbps.

802.11 current standard to describe set up the several method that virtual carrier is monitored, it is called as network allocation vector or NAV, sends (RTS/CTS) mechanism by request transmission/removing the most in particular.The RTS frame (here, the RTS frame also simply is called RTS) be sent in the RTS transmitter around NAV is set partly, and CTS frame (here, the CTS frame is also referred to as CTS) be sent in CTS transmitter (for example receiver of RTS) around carry out identical operations partly.

A problem that exists in according to 802.11 current realization relates to the problem that is called as concealed nodes.For example, in the infrastructure mode of Wireless LAN system, first equipment frame can be delivered to AP and vice versa.Similarly, second equipment can be delivered to frame AP and vice versa.Yet when for example if the distance between first equipment and second equipment is too far away, second equipment may not detect from the transmission of first equipment (so word is a concealed nodes).Because the problem of concealed nodes, the conflict that responds in equipment are avoided and symmetry aspect various complex situations can appear, cause the unequal problem of chance for the shared medium of access communication system.For example, in deferring to 802.11 system, NAV can be access in point (AP) and reset by the transmission that is commonly called the CF-end frame.The example frame form that is used for CF-end frame 10 as shown in Figure 1, this frame format comprises: corresponding to two eight hytes (quantity of exemplary eight hytes that illustrate under frame 10) of frame control field 102; Two eight hytes corresponding to duration field 104; Six eight hytes corresponding to receiver address (RA) field 106 that comprises broadcast address (BC) usually; Six eight hytes corresponding to BSSID (BSSID) field 108; And corresponding to four eight hytes of frame check sequence (FCS) field 110.When the distance between customer rs site and the AP was distant, a possible influence was that NAV can not reset in the not received zone of CF-end frame 10, caused unequal as described above the access.

Summary of the invention

The system and method that execution mode of the present disclosure provides the symmetrical transmission opportunity (TXOP) in the wireless network to block.Describe briefly, wherein a kind of execution mode of method comprises: be received in the frame that blocks TXOP around first website, and be sent in second frame that blocks TXOP around second website in response to receiving this frame.

Wherein another kind of method execution mode comprises: the frame that receives the designator of the end that comprises TXOP from access point (AP); Be sent in first frame that blocks TXOP around first website in response to receiving this designator; Receive first frame at AP; And be sent in second frame that blocks TXOP around the AP in response to receiving first frame at AP.

Wherein another kind of method execution mode comprises: send first frame at first website; After first frame, send extended inter frame space (EIFS) frame is set at first website; And send second frame at second website, and this second frame has the transmission fully corresponding to the interlude that deducts DIFS based on EIFS, and this interval is from the end of short frame.

Wherein a kind of system implementation mode comprises: become to be received in the processor that first website blocks the frame of TXOP on every side with logic configuration, in response to receiving this frame, this processor also becomes to be sent in second frame that second website blocks TXOP on every side with logic configuration.

Wherein another kind of system implementation mode comprises: block the device of the frame of TXOP around being used to be received in first website, and in response to receiving this frame, be used to be sent in the device that second website blocks second frame of TXOP on every side.

For a person skilled in the art, under the situation of checking following accompanying drawing and detailed description, other system of the present disclosure, method, feature and advantage will be or become obvious.Purpose is that all these additional system, method, feature and advantages should be included in this description, is in the scope of the present disclosure, and by the claim protection of enclosing.

Brief description of the drawings

With reference to following accompanying drawing, many aspects of the present disclosure can be better understood.Assembly in the accompanying drawing is not necessarily drawn in proportion, and emphasis changes into being placed on and clearly illustrates on the principle of the present disclosure.And identical in the accompanying drawings reference number is represented corresponding part in whole several views.

Fig. 1 is the structure chart that explanation is used for the example frame form of CF-end frame.

Fig. 2 is the structure chart of exemplary environments, can realize that in described environment symmetrical transmission opportunity (TXOP) blocks the various execution modes of (STT) system.

Fig. 3 A-3B is a structure chart of the execution mode explanation extended inter frame space (EIFS) of STT system shown in Figure 2 being avoided the aspect.

Fig. 4 is the structure chart of explanation by the mechanism of the TXOP that is used for access point (AP) startup of an execution mode application of STT system shown in Figure 2, and wherein AP is by signaling the end of TXOP in the indication that TXOP end (EOT) is set to client's last transmission.

Fig. 5 is the structure chart of the possibility of explanation mechanism shown in Figure 4, and wherein AP sends the CF-end with customer address, is the CF-end with identical customer address behind this CF-end frame.

Fig. 6 is the structure chart of the possibility of explanation mechanism shown in Figure 4, wherein AP sends the CF-end with the customer address in basic service is provided with the position of identifier (BSSID) field, and the client responds with the CF-end with BSSID, and AP responds with last CF-end.

The structure chart of Fig. 7 mechanism that is used for the TXOP that website starts that to be explanation used by execution mode of STT system shown in Figure 2, described mechanism sends CF-end with second site address in the position of BSSID field and second website by first website and responds with the CF-end with second site address in the BSSID field and be terminated.

The structure chart of the mechanism of Fig. 8 BSSID that to be explanation used by execution mode of STT system shown in Figure 2 with website, described website or with Basic Service Set (IBSS) independently or to be in the nearest beacon of AP transmission in the direct link communication.

Fig. 9 is the structure chart of explanation by the mechanism of the TXOP that is used for the website startup of an execution mode application of STT system shown in Figure 2, described mechanism sends CF-end to second website by first website, described second website responds with the CF-end that sends to the 3rd website, and the 3rd website responds and is terminated with last CF-end.

Figure 10 is the flow chart of explanation corresponding to the method execution mode of mechanism shown in Figure 4.

Figure 11 is the flow chart of explanation corresponding to the method execution mode of Fig. 5 and mechanism shown in Figure 7.

Figure 12 is the flow chart of explanation corresponding to the method execution mode of mechanism shown in Figure 6.

Figure 13 is the flow chart of explanation corresponding to the method execution mode of the mechanism shown in Fig. 8-9.

Figure 14 is that the NAV that explanation is used by the execution mode of STT system shown in Figure 2 resets machine-processed structure chart.

Figure 15 is the structure chart of the optional mechanism reset of the explanation NAV that does not use the CF-end frame shown in Figure 14.

Figure 16 is the method execution mode of mechanism is reset in explanation corresponding to the NAV shown in Figure 14-15 a flow chart.

Describe in detail

Disclosed herein is the various execution modes (also being called STT system or STT system respectively or jointly here) that symmetrical transmission opportunity (TXOP) is blocked (STT) system and corresponding mechanism or method in the wireless network.STT described herein system has comprised the function of blocking TXOP in a plurality of equipment with symmetrical manner.That is, here in the various STT system and methods of Miao Shuing, access point (AP) and customer rs site (being the client here) all are allowed to by transmitting the TXOP that the CF-end frame blocks them.This blocking is called as TXOP and blocks, and at first for certain maximum duration (for example TXOP limiting value) NAV is set here, resets NAV then when not remaining the traffic and still remaining NAV times are arranged.Usually, TXOP comprises handshaking, and it begins with the transmission such as the short frame of RTS or CTS, and the last frame end that sends or receive with transmitter (for example transmitter of RTS or CTS) of this short frame.Solved by such as the asymmetric various problems of resetting in the legacy system that comes from individual equipment (though resetting by two equipment) that produce of resetting blocking of client and AP by RTS/CTS mechanism.The various execution modes of STT system are provided for the one or more mechanism that the symmetry of TXOP is blocked.

Therefore, though mainly be in wireless lan (wlan) environment, to be described with the Basic Service Set (BSS) that disposes with infrastructure mode, but the various execution modes of STT described herein system can be applied to other system and environment similarly, for example special (ad hoc) system (for example independently BSS (IBSS) system) or DLC system and other communication system environment.In addition, though IEEE802.11 mainly is used as the example of the standard of using here in disclosed example wireless network, in fact various system and methods described herein may be used on any wireless network.And it is the some or all of functions that system (CA system) avoided in the conflict described in 11/557,516 the common pending application that the several embodiments of STT system can be included in sequence number, and this application all is contained in this to do reference.

Fig. 2 shows exemplary WLAN (WLAN) environment 100, can realize that in described environment 100 symmetrical transmission opportunity (TXOP) blocks the various execution modes of (STT) system 200.Usually, STT system 200 is configured to comprise such as a plurality of websites of website 202,204 and 206 or the Basic Service Set (BSS) of node.In the website 202,204 and 206 each can be embodied as in a plurality of Wireless Telecom Equipments, and described Wireless Telecom Equipment comprises: computer (desk-top, portable, on knee etc.), consumer electronics's (for example multimedia player), compatible telecommunication apparatus, personal digital assistant (PDA) or such as the network equipment of any other type of the TV of printer, facsimile machine, scanner, hub, switch, router, set-top box, band communication function etc.

In one embodiment, STT system 200 shown in Figure 2 comprises: access point (AP) website 202 (also being called AP simply here) and one or more customer rs site 204,206 (also being called the client respectively or jointly here).STT system 200 is configured with the pattern that is called as infrastructure mode, and thus, client 204 and 206 can directly transmit frame with AP 202, and does not transmit frame mutually.Yet the various execution modes of STT system 200 are not limited to such layout, and in some embodiments, can arrange in special or direct link communication structure.Be included in each among AP 202 and the client 204,206 is control logic 300.Control logic 300 realizes MAC layer and the service of PHY layer.The service of MAC layer provides the ability of exchange mac frame for given website.The service of MAC layer is provided at management, control or the Frame of transmission between the website 202,204,206.802.11MAC layer service used at least three kinds of frame types (data, management, control) and different subtype arranged in every type.For example, to send (RTS) frame, clear to send (CTS) frame and CF-end frame be that (for example control/CF-end represents the subtype of control types frame, CF-end) for the example of control subtype in request.After website formed applicable mac frame, the position of frame was transferred to the PHY layer and is used for transmission.It will be understood by those skilled in the art that in environment of the present disclosure control logic 300 can use a plurality of modules of having difference in functionality separately (for example hardware with and/or software) to dispose, perhaps be configured to comprise the individual module of multiple function.

Control logic 300 can realize with hardware, software or both combinations.When being realized by software whole or in part, the software by suitable instruction execution system execution of control logic 300 storage availability in memory is realized.When realizing by hardware whole or in part, the combination of each or these technology in the following technology that control logic 300 can have been known with this area realizes: have the discrete logic circuitry that is used for data-signal is realized the gate of logic function, application-specific integrated circuit (ASIC) (ASIC) with suitable combinational logic gate, programmable gate array (PGA), field programmable gate array (FPGA) etc.In one embodiment, control logic 300 can comprise PHY layer processor, MAC layer processor or both combinations (identical or independently in the unit), wherein said processor or combination include but not limited to, digital signal processor (DSP), microprocessor unit (MCU), general processor and application-specific integrated circuit (ASIC) (ASIC) or the like.

AP 202 generally is connected to the wireless network (for example Ethernet) that is not illustrated.Usually, the client, for example the client 204, are connected to AP 202 by scanning process.Scanning process can or be carried out passively by listening to by the beacon of one or more AP 202 transmission, perhaps by send to one or more AP 202 detect (probe) and select to provide best the connection (for example according to signal energy and/error rate (BER)) AP and carry out on one's own initiative.After AP was selected, for example AP 202, between client 204 and AP 202 authentication process itself took place, and the association between client 204 and AP 202 can begin then.

Association comprises the communication of wireless media 208 between client 204,206 and AP 202 by sharing.In one implementation, client 206 can represent client 204 concealed nodes, and vice versa.It is illustrated to be used for the various mechanism of handshaking and method such as Fig. 3 A to Figure 16, with the various features of the execution mode of outstanding STT system 200.Though in AP 202 or client 204 (or similarly client 206) send or receive the environment of various transmission, be described below, it should be understood that in environment of the present disclosure the various functions of STT system 200 are to finish by the control logic 300 of each website (node).And, unless help the understanding of various execution modes, that describes in 802.11 all omits from each figure (and corresponding description) with various interFrameGaps understood by one of ordinary skill in the art (for example extended inter frame space (EIFS) is lacked interFrameGap (SIFS) etc.).

Before the various symmetrical TXOP disconnect mechanism of the execution mode of describing STT system 200, the combined Fig. 3 A-3B of execution mode of the STT system 200 of the TXOP that execution AP starts is described.That is, Fig. 3 A to Fig. 3 B TXOP that starts as AP of illustrating that the execution mode of STT system 200 uses is provided with NAV and/or avoids a kind of mechanism of EIFS.With reference to figure 3A, AP 202 is by starting TXOP 302 and before TXOP 302 NAV is set with short frame 304 (for example, short in to reduce error probability) with low basic rate.Notice that square frame 302 and 304 comprises TXOP jointly.Short frame 304 comprises the duration value (for example NAV is provided with) of the desired length that equals TXOP 302.With reference to figure 3B, AP 202 avoids any EIFS by the short frame 306 (generally comprising zero duration value) that sends with low basic rate as the last frame of TXOP 302 at the end of TXOP 302.Notice that square frame 302 and 306 comprises TXOP jointly.In each case, select speed so that from all nodes (for example BSS) in the frame arrival network of AP 202.

Ensuing description and the accompanying drawing (Fig. 4 to Fig. 9) that is associated disclose the various mechanism of being used (realization) by some execution mode of STT system 200, described mechanism uses the CF-end frame to provide symmetrical TXOP to block, (here, each in these frames also is called CF-end simply).Especially, one or more plant different communication mechanism between the equipment of STT system implementation modes as shown in Fig. 4-9, and make an explanation with corresponding literal.For example, shown in Figure 4 is the square frame of each frame of expression, and described frame transmits to provide symmetrical TXOP to block between client 204 and AP 202.As noticing from Fig. 4 to Fig. 9, derive from of the box indicating (in round parentheses use " AP " shown in) of the frame of AP with top line, derive from of the box indicating (in round parentheses use " client " shown in) of client's frame with second row.The sequence of frame transmission is from left to right preferential by the time, as representing by arrow timeline 401.For example, for example communication shown in Figure 4, the RTS frame that is sent by AP 202 has begun this sequence, and the CF-end that is sent by AP 202 finishes this sequence.Notice that first address (for example BC) is the receiver address, described receiver address should be broadcast address so that the CF-end frame is received by all websites.Second address (for example BSSID) be emitter address normally, but in the one or more execution modes of describing, comprises the clean culture destination address here.

Especially, AP 202 (does not illustrate, but implication table is shown in round parentheses " AP ") send RTS frame (perhaps RTS) 402, and client 204 (do not illustrate, but implication table being shown " client " in round parentheses) responds by sending CTS frame (perhaps CTS) 404.The transmission of RTS 402 and CTS 404 causes around equipment separately the setting of (enough near so that in whole transmission time or decoded frame transmission in most of the time at least) NAV.AP 202 sends one or more Frames 406, and each in the described Frame 406 is confirmed to confirm (ACK) frame 408 by client 204.204 final data frame 406 usefulness TXOP finish (EOT) indication next " mark " from AP202 to client.This EOT indication comprises signal and the mark of arrival client 204 to respond with CF-end frame 410 after the SIFS interval.In some implementations, for example the forced response frame of ACK frame 408 (or piece confirm (BA) frame, the latter does not illustrate) can place before the CF-end frame 410.The BSSID of CF-end frame 410 (BSSID) field is carried the BSSID (for example MAC Address) of AP 202.AP 202 its BSSID of identification in the CF-end frame 410 that receives also responds these CF-end frames 410 with CF-end frame 412.Send CF-end frame 412 by AP 202, TXOP is initiatively blocked by equipment 202 and equipment 204.

Fig. 5 explanation is to the possibility of the mechanism shown in Fig. 4.Just, the last frame in TXOP that is sent by AP 202 is the CF-end frame 502 of the address (for example MAC Address) that comprises client 204 in the BSSID field.Client 204 discerns its address and responds with CF-end frame 504 back at interval at SIFS in CF-end frame 502.CF-end frame 504 also is included in the customer address in the BSSID field location.Mechanism shown in Fig. 5 is called as " to the CF-end of oneself ".

Fig. 6 explanation is to the possibility of the mechanism shown in Fig. 4.AP 202 sends the CF-end frame 602 with the client mac address in the BSSID field.The client responds with the CF-end frame 604 of BSSID with AP 202, and AP 202 responds it with the CF-end frame 606 of BSSID with AP 202.Therefore, AP 202 is as the last reflector of last CF-end frame, and it is desirable for the EIFS in BSS because relevant client receive last CF-end frames (for example CF-end206) from AP 202.The one CF-end frame 602 uses non-basic rate, is similar to thus about (last frame 406) EOT frame shown in Figure 4 and that describe to indicate and work.By a CF-end frame 602 is used non-basic rate, the NAV break-in facility is non-existent.That is, to block for NAV be effectively to the CF-end frame when sending with basic rate, thereby all clients in defined BSS can receive the decode.

The various exemplary scheme that being used to of using provide symmetry to block by STT system 200 have been described, following description (and the accompanying drawing that is associated) is concluded some above-mentioned mechanism that are used for communication between website (for example, or AP 202 or client 204,206) of mentioning and additional mechanism is provided.Promptly, Fig. 7 to Fig. 9 provides the general remark of above-mentioned mechanism by the exchange of showing the frame of two websites between website 1 (STA1) (shown in Fig. 7 to Fig. 9 top line) and website 2 (STAT2) (Fig. 7 to Fig. 9 second capable shown in), in addition also describes additional mechanism.In some embodiments, can exist and frame exchange such as the 3rd website of AP or miscellaneous equipment (shown in the third line of Fig. 8 to Fig. 9 bottom).Fig. 7 exchanges at the frame that begins after the exchange of CTS/RTS frame and data and ACK frame to the explanation of various mechanism shown in Figure 9, the latter wherein in conjunction with the accompanying drawings 4-6 be described in the above.

Fig. 7 illustrates the General Principle of some execution mode of STT system 200, in described STT system, any website that is received in the CF-end frame 702 that has its corresponding MAC Address in the position of BSSID field with CF-end frame 704 in response to CF-end frame 702.The address of using in CF-end frame 702 depends on concrete realization.Usually, if CF-end frame 704 is essential (by client or AP decisions), the address packet of the reflector of then next CF-end frame 704 is contained in the position of BSSID field of CF-end frame 702.If not needing CF-end frame 704 (being also referred to as the CF-end response frame here) and CF-end frame 702 is last frames of this sequence, then the address packet of website (for example STA2) itself is contained in BSSID field or broadcast address (BC) or does not have in directly not related with another site address any other address.Such scheme is in IBSS or also be applicable in the direct link environment.Usually, the client in infrastructure mode generally comprises the BSSID of AP, so that AP produces the CF-end response.Further, the MAC Address of the peer node that communicates with it during can being included in TXOP of the client in the IBSS pattern.AP can comprise or not comprise the address except the BSSID of AP.

Consider STA1 comprise customer rs site 204 and STA2 comprise the AP station (or simple, AP) 202 situation.Mechanism shown in Figure 7 makes the AP 202 can be at SIFS (its may be in some implementations PIFS at interval) afterwards with the CF-end 702 of another CF-end 704 in response to the BSSID that comprises coupling (for example MAC Address).Comprise the last frame among the TXOP of customer rs site 204 by the CF-end 702 of customer rs site 204 transmission, and in one embodiment, this CF-end 702 is non-acknowledgement frame (it is safe therefore transmitting CF-end 704 after SIFS).It is specific to an AP that BSSID makes CF-end702, avoids transmitting the conflict between a plurality of AP of CF-end 704.CF-end 704 removes the NAV of the whole BSS of covering around AP 202.Notice that some realizations can not need CF-end704.For example, when the distance between AP 202 and the customer rs site 204 is near, reset EIFS in the identical overlay area roughly from the single CF-end of AP 202 or customer rs site 204, because it is overlapping to a great extent to be used for the overlay area of these two equipment.Sending CF-end response (CF-end 704) by AP202 decision can be based on the estimated distance of the customer rs site 204,206 of association, and may be in conjunction with the estimated distance of the reflector of CF-end.This decision for example can be based on signal strength signal intensity that is received or PHY speed or is used for the Modulation and Coding Scheme (MCS) that communicates with customer rs site 204,206.Other mechanism can be used in this decision.

Continuing STA1 is discussed is that client 204 and STA2 are the situations of AP 202, and client 204 can be to send CF-end 702 corresponding to the duration value that is defined the time (it is provided with NAV) after the expectation CF-end 704 that is sent by AP 202.AP 202 sends CF-end 704 (CF-end response) with zero duration, this make the receiver of each CF-end retreat into again just in time or roughly just in time the identical moment (therefore, in one embodiment, followed by the existence rule (existing rule) that allows EIFS to follow CF-end).Client 204 also can add that SIFS adds that Physical Layer Convergence Protocol (PLCP) duration (it is signaled) from the CF-end duration of response of the expectation of AP 202 sends CF-end702 in the SIG of frame field or L-SIG field with equaling CF-end oneself.In one embodiment, AP 202 is allowed to ignore this physics duration and the SIFS interval that is allowed to after the actual transmissions of CF-end 702 finishes responds with CF-end 704, as can be determined from the speed of indication and the size of CF-end 702 (for example not with 20 eight hytes of HT control field, 24 eight hytes of band HT control field).In one embodiment, CF-end 704 comprises the PLCF duration of rule.The mechanism of describing below in conjunction with Figure 14 and 15 are handled when NAV and are obtained to reset and retreat the situation that there is difference in restarting in (backoff).

In some embodiments, the 3rd CF-end frame can be added in the frame sequence shown in Fig. 7 when second website comprises BSSID.This situation is shown in Figure 8, and it comprises the increase (impliedly being represented by the frame 802 of bottom or the third line) of AP.TXOP sends CF-end frame 802 to STA2 by STA1 and starts, described STA2 with CF-end frame 804 in response to AP.As directed, AP responds with the last CF-end frame 806 that has BSSID in the BSSID of CF-end frame 806 field.

In IBSS realized, as shown in Figure 9, BSSID can be by the website identification of the last IBSS beacon of transmission.As directed, STA1 sends the CF-end frame 902 that is addressed in STA2.STA2 responds with the CF-end frame 904 at the BSSID place that is addressed in STA2.STA3 responds with CF-end frame 906.BSSID can be that (for example, address STA3) perhaps comprises that in the communication between STA1 and the STA2 under the situation of direct linking communications can be the address of AP for the website of the last beacon of transmission in the IBSS.

In some embodiments, the receiver address (RA) of CF-end frame equals broadcast address, and this has guaranteed that all websites in the scope receive the CF-end frame and handle same frame.The position of BSSID can be used for indicating the destination of CF-end.And in some embodiments, it is enough that the identification of CF-end type/subtype is blocked NAV for receiver.In such execution mode, the RA of CF-end frame can be used for storing CF-end transponder address, and the BSSID field can be used for storing this BSSID.

The various execution modes of STT system 200 have above been described, should understand in environment of the present disclosure, comprise: the final data frame (1002) that sends the transmission opportunity (TXOP) that includes transmission opportunity end (EOT) designator by AP corresponding to mechanism shown in Figure 4 with at a kind of method execution mode that is called as STT method 200a shown in flow process Figure 10; Receive this final data frame (1004) by the client; The client responds AP by the CF-end frame that transmission includes the identifier (for example MAC Address etc.) of AP, to block TXOP (1006) around the client; AP receives the CF-end frame (1008) with identifier; And AP has the CF-end frame of identical identifier to block TXOP (1010) around AP to client's transmission.

The part that will be appreciated that method execution mode 200a realizes at each equipment place, and therefore these parts can be described from the viewpoint of each equipment of system 200.For example, comprise corresponding to the method execution mode of the method 200a viewpoint from AP: (by AP) sends and includes the final data frame that transmission opportunity finishes the transmission opportunity (TXOP) of (EOT) designator; And include in response to reception AP identifier the CF-end frame and block TXOP around the client; Send CF-end frame and around AP, block TXOP to the client with identical identifier.

Comprise corresponding to another method execution mode of method 200a viewpoint from the client: (by the client) receives the last frame from the transmission opportunity (TXOP) of AP; This final data frame has the transmission opportunity that is included in wherein and finishes (EOT) designator; Come in response to this last frame by the CF-end that sends the identifier that includes AP to AP, around the client, to block TXOP and to impel AP to send the CF-end frame and come around AP, to block TXOP.

Comprise corresponding to Fig. 5 and mechanism shown in Figure 7 and at another mode execution mode shown in the flow chart kind of Figure 11, that be called as STT method 200b: at the terminal CF-end frame that sends the address that includes second website (for example client) of TXOP, come around first website, to block TXOP (1102) by first website (for example AP); Receive CF-end frame (1104) by second website from first website; Second website include by transmission second website the address the CF-end frame and in response to first website, to block TXOP (1106) around second website.

The part that will be appreciated that method execution mode 200b at each equipment place (for example no matter website is configured to AP or client) realize that and therefore these parts can be described from the viewpoint of each equipment of system 200.For example, a method execution mode corresponding to method 200b of realizing at first website (for example AP) comprises: the last frame that receives TXOP at first website from second website (for example client); In response to the last frame that receives this TXOP, send the CF-end frame of the address that includes second website at the end of TXOP, around first website, to block TXOP and to impel second website to send the CF-end frame around second website, to block TXOP.

In addition, a method execution mode corresponding to method 200b of realizing at the second website place comprises: (at second website) receives the CF-end frame of the address that includes second website, and described CF-end frame is used for blocking TXOP around first website; The CF-end frame that includes the address of second website by transmission comes in response to first website, to block TXOP around second website.

Comprise corresponding to mechanism shown in Figure 6 and at another method execution mode shown in the flow chart kind of Figure 12, that be called as STT method 200c: AP sends the CF-end frame (1202) of the address that includes the client with non-basic rate (and therefore as EOT designator); The client receives this CF-end frame (1204); The client includes the address of AP by transmission CF-end frame responds, and this CF-end frame blocks TXOP (1206) around the client; AP receives the CF-end frame (1208) that is sent by the client; AP includes the address of AP by transmission CF-end frame responds, and makes AP as the last reflector (1210) that blocks the last CF-end frame of TXOP around AP.

The part that will be appreciated that method execution mode 200c realizes at each equipment place, and therefore the method execution mode can be described from AP and client's viewpoint.A method execution mode corresponding to method 200c of realizing at the AP place comprises: AP sends the CF-end frame of the address that includes the client with non-basic rate (and therefore as EOT designator); And block the CF-end frame in response to client-TXOP that reception includes the address of AP, and the CF-end frame that includes the address of AP by transmission responds, and this blocks TXOP around AP.

In addition, a method execution mode corresponding to method 200c of realizing in the customers' place comprises: show the CF-end frame that non-basic rate (and therefore as EOT indicating device) receives the address that includes the client greatly by the client; And respond by the CF-end frame that transmission includes the address that sends AP, this blocks TXOP and impels AP to be sent in the last CF-end frame that blocks TXOP around the AP around the client.

Comprise to mechanism shown in Figure 9 and at another method execution mode shown in the flow chart of Figure 13, that be called as STT method 200d corresponding to Fig. 8: send the CF-end frame of the address that includes second website by first website at the end of TXOP, around first website, to block TXOP (1302); Receive CF-end frame (1304) by second website from first website; Second website responds by sending the CF-end frame that includes identifier to the 3rd website, to block TXOP (1306) around second website; The 3rd website receives CF-end response frame (1308); The 3rd website responds by sending the CF-end response frame that includes identifier to second website, to block TXOP (1310) around the 3rd website.

Those of ordinary skills will be appreciated that, in environment of the present disclosure, each equipment that participates in the illustrated method step of Figure 13 is realized the each several part of described method 200d, described method 200d can be described to be similar to such as this mode of above having described in Figure 10-12 based on the method for viewpoint, and therefore in order briefly and here to omit.

Figure 14 illustrates the various mechanism of the TXOP that the client of the execution mode that is used for STT 200 starts, and more specifically, concentrate on the NAV that relates to CF-end frame or having of in specific environment, moving and the frame of the similar functions of CF-end frame and reset and retreat the beginning problem.The following part of describing is based on being that client and STA2 are the above discussion of the situation of AP corresponding to Fig. 7 at STA1.Obtain to reset and retreat difference in restarting in order to solve NAV when, the SIFS time that the client can be transmitted in after the CF-end frame 1402 sends the short frame (EIFS is provided with frame) 1404 with definition frame verification sequence (FCS) field 110 (Fig. 1), the Frame Check Sequence of described definition (FCS) be not correct FCS (for example, if FCS is correct, then website starts EIFS rather than DCF interFrameGap/arbitration frame interbody spacer or DIFS/AIFS).The transmission of this short frame 1404 causes that with pattern described above receiver (for example the client 204,206) starts EIFS.AP202 (for example postpones, according to SIFS+EIFS frame+EIFS-DIFS-CF-end frame is set, by at interval 1401 expressions of duration) transmission of CF-end frame 1406, so that the transmission of frame 1406 exactly (or that's about the size of it) is finished when EIFS-DIFS (EIFS-DIFS is by the duration time interval of 1403 expressions) finishes, (for example 204,206) starts DIFS (or more generally, AIFS) in the identical time so that arbitrary client.DIFS relates to first standing part that DCF retreats (DIFS), and AIFS relates to EDCA and retreats (AIFS).As known, EDCA is similar to DCF but has QoS difference (802.11e).AP 202 do not start EIFS and ignore in the middle of EIFS frame 1404 is set.Therefore, EIFS is provided with frame 1404 and makes AIFS start the client 204,206 that can not receive from the CF-end frame 1406 of AP 202.From the CF-end frame 1406 of AP 202 at this moment between during be transmitted so that all nodes start DIFS (or AIFS) in the identical moment.Notice that in some embodiments, it can be zero length frame (preamble that does not for example have the MAC payload) that EIFS is provided with frame 1404.

Figure 15 is the structure chart of the principle of the explanation mechanism of not using the CF-end frame shown in Figure 14.In other words, the CF-end frame 1402 usefulness EOT frames 1502 of Figure 14 replace, and the CF-end frame 1406 usefulness ACK frames 1504 of Figure 14 replace.All nodes that the illustrated mechanism of Figure 15 is used in client 204 in the network or AP 202 or the two the scope begin to retreat (for example, the part of node does not need to wait for that EIFS finishes) at synchronization.EOT frame 1502 sends to AP 202 at SIFS that EIFS is provided with frame 1404 after at interval.AP202 is by similar delay 1401 and use and the similar mode of mechanism described in conjunction with Figure 14, with ACK frame 1504 in response to EOT frame 1502 (and ignore EIFS frame 1404 is set).ACK frame 1504 is being provided with the identical moment end at frame 1404 interval 1403 after terminal with EIFS.Notice that in some embodiments, AP can start EIFS in the identical or roughly the same moment with the client frame is set.

Described Figure 14 to various mechanism shown in Figure 15, an execution mode that is called as 200e and method as shown in figure 16 that comprises these machine-processed STT systems 200 comprises: client 204 sends the final data frame of TXOP to AP 202 (1602); Last frame has the form of given AP or the distinctive CF-end frame of EOT frame; Send EIFS frame is set; Receive CF-end frame (1606) by AP 202 (definition be spaced apart SIFS described in conjunction with Figure 14, PIFS or duration 1401) after the interval of definition; And send CF-end response frame or ACK frame in response to decision, come (for example, BSS) to remove NAV (1610) by send CF-end response frames or ACK frame to client 204 for network.Do not send the CF-end response frame in response to decision, as mentioned above, the CF-end frame works to remove NAV (1612).

Those skilled in the art will recognize that in environment of the present disclosure, each equipment that participates in method shown in Figure 16 is carried out the part of described method 200e, described method 200e can be described with this mode based on the method for viewpoint that is similar to such as above having described in Figure 10-12, and therefore in order briefly and here to omit.

Because description above will be appreciated that various execution modes can be described with following mode and be considered in the scope of the present disclosure.

A: a kind of symmetrical transmission opportunity (TXOP) method for cutting comprises: be received in the frame that first website blocks TXOP on every side; And be sent in second frame that blocks TXOP around second website in response to received frame.

The method of B.A, wherein received frame comprises reception CF-end frame.

The method of C.A, wherein received frame comprises the CF-end frame that receives the address with second website.

The method of D.C, the destination that wherein is used for CF-end is positioned at basic service set identification (BSSID) field.

The method of E.A, wherein received frame is included in customer rs site or access point reception.

The method of F.A wherein sends second frame and comprises that transmission CF-end response frame is to first website, second website or the 3rd website.

The method of G.A wherein sends described second frame and comprises: comprise the address of first website, the address of second website or the address of the 3rd website.

The method of H.A wherein sends second frame and comprises and send to customer rs site or access point.

The method of I.A also is included in the 3rd website and receives second frame.

The method of J.I also comprises in response to receiving second frame at the 3rd website, is sent in the 3rd frame that the 3rd website blocks TXOP on every side.

The method of K.J wherein sends the 3rd frame and comprises the 3rd frame that sends the address with the 3rd website.

The method of L.A, wherein transmission is included in the time interval of short interFrameGap (SIFS) or the time interval transmission afterwards of PCF interFrameGap (PIFS).

The method of M.A, wherein reception comprises: receive with the NAV duration value, the NAV duration value is included in the expection of second frame and is sent out a period of time afterwards.

The method of N.A, wherein reception comprises: add that with the duration that is substantially equal to frame the interval of SIFS adds the physical layer convergence protocol duration received frame of the expectation duration of second frame.

O. a symmetrical transmission opportunity (TXOP) method for cutting comprises: from access point (AP) received frame of the designator of the end that comprises TXOP; Be sent in first frame that blocks TXOP around first website in response to receiving this designator; Receive first frame at AP; And be sent in second frame that blocks TXOP around the AP in response to receiving first frame at AP.

The method of P.O, wherein received frame comprises receiving data frames.

The method of Q.O also is included in first website, confirmation of receipt (ACK) frame before receiving first frame.

The method of R.O wherein sends first frame and transmission second frame comprises that the address with AP sends first frame and second frame.

The method of S.R, wherein the address of AP is included in the address in the BSSID field of first frame or second frame.

T. a symmetrical transmission opportunity (TXOP) method for cutting comprises: send first frame at first website; After first frame, send extended inter frame space (EIFS) at first website frame is set; And sending second frame at second website, described second frame has the transmission fully corresponding to the interlude that deducts DIFS based on EIFS, the described spaced apart end that starts from described short frame.

The method of U.T, each all comprises transmission CF-end frame wherein to send first frame and transmission second frame.

The method of V.T wherein sends first frame and transmission second frame comprises the transmission end of transmission (EOT) frame and acknowledgement frame respectively.

The method of W.T, wherein sending second frame and EIFS, that the existence of frame is set is irrelevant.

The method of X.T, wherein EIFS is provided with frame and comprises fault frame check sequence (FCS).

The method of Y.T, wherein EIFS is provided with frame and is made up of PHY header (header).

Z. a symmetrical transmission opportunity (TXOP) truncated system, comprise processor, described processor becomes to be received in the frame that blocks TXOP around first website with logic configuration, and processor also becomes in response to received frame with logic configuration, is sent in second frame that blocks TXOP around second website.

The system of AA.Z, wherein frame comprises the CF-end frame.

The system of AB.Z, wherein frame comprises the CF-end frame of the address with second website.

The system of AC.Z, wherein logic is positioned at customer rs site or access point.

The system of AD.Z, wherein processor also becomes to send the CF-end response frame to first website, second website or the 3rd website with logic configuration.

The system of AE.Z, wherein second frame comprises the address of first website, the address of second website, or the address of the 3rd website.

The system of AF.Z, wherein processor also becomes to customer rs site and access point to send with logic configuration.

The system of AG.Z also comprises the 3rd website, and the 3rd website comprises second memory with second logic and serves as second processor that receives second frame with second logic configuration.

The system of AH.AG, wherein second processor becomes in response to receiving second frame to be sent in the 3rd frame that the 3rd website blocks TXOP with second logic configuration.

The system of AI.AH, wherein the 3rd frame comprises the address of the 3rd website.

The system of AJ.Z, wherein logic is included in wireline equipment or the wireless device.

The system of AK.z, wherein logic is included in computer, consumer-elcetronics devices, set-top box, television set, Video Storage System, telecommunication equipment or the PDA(Personal Digital Assistant).

AL. a symmetrical transmission opportunity (TXOP) truncated system comprises: be used to be received in the device that first website blocks the frame of TXOP on every side; And be used to be sent in the device that blocks second frame of TXOP around second website in response to received frame.

AM. a symmetrical transmission opportunity (TXOP) truncated system, comprise: first website, described first website includes first logic receiving the frame of the designator include the TXOP end from access point (AP), and is sent in first frame that first website blocks TXOP in response to receiving this designator; And AP, described AP comprises second logic receiving first frame, and is sent in second frame that AP blocks TXOP in response to receiving this first frame.

The system of AN.AM, wherein said frame comprises Frame.

The system of AO.AM, wherein first logic also is configured to confirmation of receipt (ACK) frame before receiving first frame.

The system of AP.AM, wherein first frame and second frame each all comprise the address of AP.

The system of AQ.AP, wherein the address of AP comprises the address in the BSSID field of first frame or second frame.

The system of AR.AM, wherein first logic and second logic each be included in wireline equipment or the wireless device.

The system of AS.AM, wherein first logic and second logic each be included in computer, consumer-elcetronics devices, set-top box, television set, Video Storage System, telecommunication apparatus or the PDA(Personal Digital Assistant).

AT. a symmetrical transmission opportunity (TXOP) truncated system comprises: the device that is used for receiving from access point (AP) frame of the designator that includes the TXOP end; And, be used to be sent in the device that first website blocks first frame of TXOP in response to receiving this designator; And be used to receive first frame, and, be used to be sent in the device that AP blocks second frame of TXOP in response to receiving this first frame.

AU. a symmetrical transmission opportunity (TXOP) truncated system, comprising: first website, described first website include first logic and to send first frame and send extended inter frame space (EIFS) after first frame frame are set; And second website, described second website becomes to send second frame with second logic configuration, and described second frame has the transmission fully corresponding to the time in the time interval that deducts DIFS based on EIFS, the described spaced apart end that starts from described short frame.

The system of AV.AU, wherein first frame and second frame each all comprise the CF-end frame.

The system of AW.AU, wherein first frame and second frame comprise the end of transmission (EOT) frame and acknowledgement frame respectively.

The system of AX.AU wherein sends second frame and is independent of the existence that EIFS is provided with frame.

The system of AY.AU, wherein first logic and second logic each be included in wireline equipment or the wireless device.

The system of AZ.AU, wherein first logic and second logic are included in computer, consumer-elcetronics devices, set-top box, television set, Video Storage System, telecommunication apparatus or the PDA(Personal Digital Assistant) separately.

BA. a symmetrical transmission opportunity (TXOP) truncated system comprises: be used for sending first frame and send the device that EIFS is provided with frame after first frame at first website; And the device that is used for sending at second website second frame, described second frame has the transmission fully corresponding to the interlude that deducts DIFS based on EIFS, the described spaced apart end that starts from short frame.

BB. a symmetrical transmission opportunity (TXOP) method for cutting comprises: send first frame that is addressed in second website at first website; And after first frame, frame is set at first website and second website transmission extended inter frame space (EIFS);

The method of BC.BB wherein sends first frame and comprises transmission CF-end frame.

Any process prescription in the flow chart or square can be regarded as module, section or the part of expression code, it comprises the specific logical function that is used for implementation procedure or the one or more executable instructions of step, and optional realization can be included in the scope of the present disclosure, function wherein can not according to shown in or the order discussed carry out, comprise roughly the same or opposite order, this depends on the function that is comprised, and should be appreciated that as disclosure those skilled in the art.

Should emphasize that above-mentioned execution mode of the present disclosure only is the possible embodiment that realizes, state just to clear understanding principle of the present disclosure.Can carry out multiple variation and change to the execution mode of the present disclosure of foregoing description, not depart from spirit and scope of the present disclosure in fact.All these changes and variation here are intended to be comprised in the scope of the present disclosure and by following claim to be protected.

Claims

1. a symmetrical transmission opportunity (TXOP) method for cutting comprises:

Be received in the frame that first website blocks TXOP on every side; And

In response to receiving described frame, be sent in second frame that second website blocks described TXOP on every side.

2. the method for claim 1, the step that wherein receives described frame comprise and receive the CF-end frame.

3. the method for claim 1, wherein the described step of received frame comprises the CF-end frame that receives the address with described second website.

4. method as claimed in claim 3, the destination that wherein is used for described CF-end is positioned at basic service set identification (BSSID) field.

5. the method for claim 1, wherein the described step of received frame is included in the customer rs site place or the access point place receives.

6. the method for claim 1, the described step that wherein sends second frame comprise and send the CF-end response frame to described first website, described second website or the 3rd website.

7. the method for claim 1, the described step that wherein sends second frame comprises: comprise the address of the address of described first website, described second website or the address of the 3rd website.

8. the method for claim 1, the described step that wherein sends second frame comprise and send to customer rs site or access point.

9. the method for claim 1 also is included in the 3rd website place and receives described second frame.

10. method as claimed in claim 9 also comprises in response to receiving described second frame at described the 3rd website place, is sent in the 3rd frame that described the 3rd website blocks described TXOP on every side.

11. method as claimed in claim 10, the described step that wherein sends the 3rd frame comprises described the 3rd frame that sends the address with described the 3rd website.

12. the method for claim 1, wherein the described step of Fa Songing sends after being included in time interval of time interval of short interFrameGap (SIFS) or PCF interFrameGap.

13. the method for claim 1, wherein the described step of Jie Shouing comprises: receive with the NAV duration value, described NAV duration value is included in described second frame expection and is sent out a period of time afterwards.

14. the method for claim 1, wherein the described step of Jie Shouing comprises: add that with the duration that equals described frame in fact the SIFS time interval adds the physical layer convergence protocol duration of the expectation duration of the above second frame and receives described frame.

15. a symmetrical transmission opportunity (TXOP) method for cutting comprises:

Access point (AP) received frame from the designator of the end that comprises TXOP;

In response to receiving described designator, be sent in first frame that first website blocks described TXOP on every side;

Receive described first frame at described AP; And

In response to receive described first frame at described AP, be sent in second frame that described AP blocks described TXOP on every side.

16. method as claimed in claim 15, wherein the described step of received frame comprises receiving data frames.

17. method as claimed in claim 15 also is included in described first website, confirmation of receipt (ACK) frame before receiving described first frame.

18. method as claimed in claim 15 wherein sends the described step of first frame and the described step of transmission second frame and comprises that the address with described AP sends described first frame and described second frame.

19. method as claimed in claim 18, the described address of wherein said AP are included in the address in the BSSID field of described first frame or described second frame.

20. a symmetrical transmission opportunity (TXOP) method for cutting comprises:

Send first frame at first website;

After described first frame, send extended inter frame space (EIFS) at described first website frame is set; And

Send second frame at second website, described second frame has the transmission fully corresponding to the time in the time interval that deducts DIFS based on EIFS, and the described time interval starts from the end of described short frame.

21. method as claimed in claim 20, wherein send the described step of first frame and send second frame described step each all comprise and send the CF-end frame.

22. method as claimed in claim 20 wherein sends the described step of first frame and the described step of transmission second frame and comprises the transmission end of transmission (EOT) frame and acknowledgement frame respectively.

23. method as claimed in claim 20, the existence that the transmission of wherein said second frame and described EIFS are provided with frame has nothing to do.

24. method as claimed in claim 20, wherein said EIFS is provided with frame and comprises fault frame check sequence (FCS).

25. method as claimed in claim 20, wherein said EIFS is provided with frame and is made up of the PHY header.

26. a symmetrical transmission opportunity (TXOP) truncated system comprises:

Processor, described processor becomes to be received in the frame that first website blocks TXOP on every side with logic configuration, and in response to receiving described frame, described processor also becomes to be sent in second frame that second website blocks TXOP on every side with described logic configuration.

27. system as claimed in claim 26, wherein said frame comprises the CF-end frame.

28. system as claimed in claim 26, wherein said frame comprises the CF-end frame of the address with described second website.

29. system as claimed in claim 26, wherein said logic is positioned at customer rs site or access point.

30. system as claimed in claim 26, wherein said processor also becomes to send the CF-end response frame to described first website, second website or the 3rd website with described logic configuration.

31. system as claimed in claim 26, wherein said second frame comprises the address of the address of described first website, described second website or the address of the 3rd website.

32. system as claimed in claim 26, wherein said processor also becomes to customer rs site or access point to send with described logic configuration.

33. system as claimed in claim 26 also comprises the 3rd website, described the 3rd website comprises second memory with second logic and serves as second processor that receives described second frame with described second logic configuration.

34. system as claimed in claim 33, wherein said second processor becomes in response to receiving described second frame with described second logic configuration, is sent in the 3rd frame that described the 3rd website blocks described TXOP.

35. system as claimed in claim 34, wherein said the 3rd frame comprises the address of described the 3rd website.

36. a symmetrical transmission opportunity (TXOP) truncated system comprises:

Be used to be received in the device that first website blocks the frame of TXOP on every side; And

In response to receiving described frame, be used to be sent in the device that second website blocks second frame of described TXOP on every side.

37. a symmetrical transmission opportunity (TXOP) method for cutting comprises:

Send first frame that is addressed in second website at the first website place; And

After described first website and described second website are in described first frame, send extended inter frame space (EIFS) frame is set.

38. method as claimed in claim 37 wherein sends described first frame and comprises transmission CF-end frame.