CN101401334B

CN101401334B - Symmetric transmit opportunity(txop) truncation

Info

Publication number: CN101401334B
Application number: CN200780008665.5A
Authority: CN
Inventors: 门佐·温汀克
Original assignee: Spyder Navigations LLC
Current assignee: Intellectual Ventures I LLC
Priority date: 2006-01-10
Filing date: 2007-01-10
Publication date: 2013-03-13
Anticipated expiration: 2027-01-10
Also published as: CN101401334A

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

Symmetrical 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 priority of the U.S. Provisional Application of " CF-End Response ", and all these applications all are contained in this to make reference.

The sequence number that the application requires on January 10th, 2006 to submit to is the priority that 60/757,827 name is called the common unsettled U.S. Provisional Application of " Symmetric TXOP Truncation ", and it is contained in this to make reference.

Background technology

Correlation technique

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

WLAN (wireless local area network) (LAN) normal operation infrared (IR) or radio frequency (RF) communication channel communicate between portable or mobile compute 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) media 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 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/remove (RTS/CTS) mechanism that sends by request 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 partly identical operation.

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, the first equipment frame can be delivered to AP and vice versa.Similarly, the second equipment can be delivered to frame AP and vice versa.Yet, if when for example the distance between the first equipment and the second equipment was too far away, the second equipment may not detect from the transmission of the first equipment (so word is 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.Be used for the example frame form of 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 usually comprises broadcast address (BC); 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 impact was that the not received zone of CF-end frame 10 can not reset NAV, caused as described above unequal access.

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.

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 the first website, and be sent in the second frame that blocks TXOP around the 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 the first frame that blocks TXOP around the first website in response to receiving this designator; Receive the first frame at AP; And be sent in the second frame that blocks TXOP around the AP in response to receiving the first frame at AP.

Wherein another kind of method execution mode comprises: send the first frame at the first website; After the first frame, send extended inter frame space (EIFS) at the first website frame is set; And send the second frame at the second website, and this second frame has the fully transmission 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 the 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 the second frame that the 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 for being received in the first website, and in response to receiving this frame, be used for being sent in the device that the second website blocks the second frame of TXOP on every side.

For a person skilled in the art, in 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 reference number represents corresponding part in whole several views in the accompanying drawings.

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 the 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 that the mechanism of the TXOP that is used for access point (AP) startup that is used by an execution mode of STT system shown in Figure 2 is described, wherein AP signals the end of TXOP by the indication that TXOP end (EOT) is set in the last transmission to the client.

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 arranges 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 the second station dot address in the position of BSSID field and the second website by the first website and responds with the CF-end with the second station dot address in the BSSID field and be terminated.

The structure chart of the mechanism of Fig. 8 BSSID with website that to be explanation used by execution mode of STT system shown in Figure 2, 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 that explanation is by the structure chart of 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 the second website by the first website, described the 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 that explanation is corresponding to the flow chart of the method execution mode of mechanism shown in Figure 4.

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

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

Figure 13 is that explanation is corresponding to the flow chart of 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 that resets of the explanation NAV that does not use the CF-end frame shown in Figure 14.

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

Describe in detail

Disclosed herein is the various execution modes (also being called respectively or jointly STT system or STT system 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 in the mode of symmetry.That is, in the various STT system and methods of here describing, access point (AP) and customer rs site (being the client here) all are allowed through transmission CF-end frame and block their TXOP.This blocking is called as TXOP and blocks, and at first for certain maximum duration (for example TXOP limiting value) NAV is set here, then resets NAV in more remaining NAV times not remaining the traffic and have still.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 that produce that reset that resetting in the legacy system that comes from individual equipment (although being reset by two equipment by RTS/CTS mechanism) blocking of client and AP.The various execution modes of STT system are provided for the one or more mechanism that the symmetry of TXOP is blocked.

Therefore, although mainly be in WLAN (wireless local area network) (WLAN) environment with the Basic Service Set (BSS) that disposes with infrastructure mode, to be described, 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, although IEEE802.11 mainly is used as the example of the standard of using here in published 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 several execution modes of STT system can be included in sequence number, and this application all is contained in this to make 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 website 202, a plurality of websites of 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 (such as multimedia player), compatible telecommunication apparatus, personal digital assistant (PDA) or such as printer, facsimile machine, scanner, hub, switch, router, set-top box, with the network equipment of any other type of the TV of communication function etc.

In one embodiment, STT system 200 shown in Figure 2 comprises: access point (AP) website 202 (also being called simply AP here) and one or more customer rs site 204,206 (also being called respectively or jointly the client here).STT system 200 is configured with the pattern that is called as infrastructure mode, thus, client 204 and 206 can with the direct transferring frames of AP202, and transferring frames not 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 AP202 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, request sends (RTS) frame, clear to send (CTS) frame, and the CF-end frame is that (for example control/CF-end represents to control the subtype of type frame, CF-end) for the example of control subtype.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 control logic 300 can use a plurality of modules (for example hardware and/or software) that have separately difference in functionality to dispose in environment of the present disclosure, perhaps be configured to comprise the individual module of several functions.

Control logic 300 can realize with hardware, software or both combinations.When being realized by software whole or in part, control logic 300 can realize with the software by suitable instruction execution system execution that is stored in the memory.When being realized 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 for the discrete logic circuitry that 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) etc.

AP202 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 AP202 by scanning process.Scanning process can or be carried out passively by listening to by the beacon of one or more AP202 transmission, perhaps by send to one or more AP202 detect (probe) and select to provide Best link (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 authentication process itself occured in AP202 between client 204 and AP202, and then the association between client 204 and AP202 can begin.

Association comprise by the wireless media 208 shared client 204,206 and AP202 between communication.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.Although the below is described in AP202 or client 204 (or similarly client 206) send or receive the environment of various transmission, 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 arranges NAV and/or avoids a kind of mechanism of EIFS.With reference to figure 3A, AP202 is by starting TXOP302 and NAV was set before TXOP302 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 arranges) of the desired length that equals TXOP302.With reference to figure 3B, AP202 avoids any EIFS by the short frame 306 (generally comprising zero duration value) that sends with low basic rate as the last frame of TXOP302 at the end of TXOP302.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 AP202.

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 provides symmetrical TXOP to block with the CF-end frame, (here, each in these frames also is called CF-end simply).Especially, the different communication mechanism between the equipment of one or more of STT System Implementation modes and makes an explanation with corresponding literal as shown in Fig. 4-9.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 AP202.As noticing from Fig. 4 to Fig. 9, the frame that derives from AP is with the box indicating of top line (in round parentheses with shown in " AP "), derives from client's frame with the box indicating of the second row (in round parentheses shown in the usefulness " client ").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 AP202 has begun this sequence, and the CF-end that is sent by AP202 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, AP202 (does not illustrate, but implication table is shown in round parentheses " AP ") transmission 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 RTS402 and CTS404 causes around equipment separately the setting of (enough near so that in whole transmission time or at least decoded frame transmission in most of the time) NAV.AP202 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 AP202.AP202 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 AP202, TXOP is initiatively blocked by equipment 202 and equipment 204.

Fig. 5 explanation is to the possibility of the mechanism shown in Fig. 4.Namely, the last frame in TXOP that is sent by AP202 is the CF-end frame 502 of the address (for example MAC Address) that comprises client 204 in the BSSID field.Client 204 identifies its address and responds with CF-end frame 504 behind the SIFS interval 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.AP202 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 AP202, and AP202 responds it with the CF-end frame 606 of BSSID with AP202.Therefore, AP202 is as the last reflector of last CF-end frame, and it is desirable for the EIFS in BSS, because related client receives last CF-end frame (for example CF-end206) from AP202.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 for 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 AP202 or client 204,206) of mentioning and additional mechanism is provided.Namely, 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) (shown in Fig. 7 to Fig. 9 the second row), 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 for 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 by reference to 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.Address in the 702 interior uses of CF-end frame depends on concrete realization.Usually, if CF-end frame 704 is essential (being determined by client or AP), then the address packet of the reflector of 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 AP202 can be at SIFS (it may be the PIFS interval in some implementations) afterwards with the CF-end702 of another CF-end704 in response to the BSSID that comprises coupling (for example MAC Address).Comprised the last frame among the TXOP of customer rs site 204 by the CF-end702 of customer rs site 204 transmission, and in one embodiment, this CF-end702 is non-acknowledgement frame (it is safe therefore transmitting CF-end704 after SIFS).It is specific to an AP that BSSID makes CF-end702, avoids transmitting the conflict between a plurality of AP of CF-end704.CF-end704 removes the NAV of the whole BSS of covering around AP202.Notice that some realizations can not need CF-end704.For example, when the near distance between AP202 and the customer rs site 204, reset roughly EIFS in the identical overlay area from the single CF-end of AP202 or customer rs site 204, because it is overlapping to a great extent to be used for the overlay area of these two equipment.Determine sending CF-end response (CF-end704) by AP202 can be based on the customer rs site 204 of association, 206 estimated distance, and may be in conjunction with the estimated distance of the reflector of CF-end.This decision for example can be based on the signal strength signal intensity that receives 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 AP202, and client 204 can be to send CF-end702 corresponding to the duration value that is defined the time (it arranges NAV) after the expectation CF-end704 that is sent by AP202.AP202 sends CF-end704 (CF-end response) with zero duration, this so that the receiver of each CF-end retreats into just in time again or roughly just in time the identical moment (therefore, in one embodiment, followed by allowing EIFS to follow the existence rule (existing rule) of 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 AP202 sends CF-end702 in the SIG of frame field or L-SIG field with equaling CF-end oneself.In one embodiment, AP202 is allowed to ignore this physics duration and the SIFS interval that is allowed to after the actual transmissions of CF-end702 finishes responds with CF-end704, as can be determined from the speed of indication and the size of CF-end702 (for example not with 20 eight hytes of HT control field, with 24 eight hytes of HT control field).In one embodiment, CF-end704 comprises the PLCF duration of rule.When the mechanism of describing below in conjunction with Figure 14 and 15 are processed NAV and are obtained to reset and retreat (backoff) and restart the middle situation that has difference.

In some embodiments, the 3rd CF-end frame can be added in the frame sequence shown in Fig. 7 when the second website comprises BSSID.This situation is shown in Figure 8, and it comprises the increase (impliedly the frame 802 by bottom or the third line represents) 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 station recognition 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 in 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 process 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 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: the final data frame (1002) that is sent the transmission opportunity (TXOP) that includes transmission opportunity end (EOT) designator by AP; Receive this final data frame (1004) by the client; The client responds AP by the CF-end frame that transmission includes the identifier (such as 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 the CF-end frame with identical identifier and around AP, block TXOP to the client.

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 the second website (for example client) of TXOP, come around the first website, to block TXOP (1102) by the first website (for example AP); Receive CF-end frame (1104) by the second website from the first website; The second website include by transmission the second website the address the CF-end frame and in response to the first website, to block TXOP (1106) around the 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 the first website (for example AP) comprises: the last frame that receives TXOP at the first website from the 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 the second website at the end of TXOP, around the first website, to block TXOP and to impel the second website to send the CF-end frame around the second website, to block TXOP.

In addition, a method execution mode corresponding to method 200b of realizing at the second website place comprises: (at the second website) receives the CF-end frame of the address that includes the second website, and described CF-end frame is used for blocking TXOP around the first website; The CF-end frame that includes the address of the second website by transmission comes in response to the first website, to block TXOP around the 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 greatly the CF-end frame that non-basic rate (and therefore as EOT indicating device) receives the address that includes the client 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 the second website by the first website at the end of TXOP, around the first website, to block TXOP (1302); Receive CF-end frame (1304) by the second website from the first website; The second website responds by sending the CF-end frame that includes identifier to the 3rd website, to block TXOP (1306) around the 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 the 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 based on the method for viewpoint of above having described in Figure 10-12, and therefore in order briefly and here to omit.

Figure 14 explanation is for the various mechanism of the TXOP of client's startup of the execution mode of STT200, 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 for STA1.Obtain to reset and retreat difference in restarting in order to solve when NAV, the SIFS time that the client can be transmitted after CF-end frame 1402 sends the short frame (EIFS arranges 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 interFrameGap or DIFS/AIFS).The transmission of this short frame 1404 causes that with pattern described above receiver (for example client 204,206) starts EIFS.AP202 (for example postpones, according to SIFS+EIFS frame+EIFS-DIFS-CF-end frame is set, by duration interval 1401 expression) 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) at same time so that arbitrary client.DIFS relates to the 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).AP202 do not start EIFS and ignore in the middle of EIFS frame 1404 is set.Therefore, EIFS arranges frame 1404 so that AIFS starts the client 204,206 that can not receive from the CF-end frame 1406 of AP202.From the CF-end frame 1406 of AP202 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 the zero length frame preamble of MAC payload (for example without) that EIFS arranges 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 AP202 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 AP202 after EIFS arranges the SIFS interval of frame 1404.AP202 is by similar delay 1401 and use the mode similar with 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 arranging 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 AP202 (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 AP202 (definition be spaced apart SIFS described in conjunction with Figure 14, PIFS or duration 1401) after the interval of definition; And in response to determine sending CF-end response frame or ACK frame, come (for example, BSS) to remove NAV (1610) for network by send CF-end response frames or ACK frame to client 204.Do not send the CF-end response frame in response to determining, 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 the first website blocks TXOP on every side; And be sent in the second frame that blocks TXOP around the 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 the second frame and comprises that transmission CF-end response frame is to the first website, the second website or the 3rd website.

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

The method of H.A wherein sends the 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 the second frame.

The method of J.I also comprises in response to receiving the 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 afterwards transmission of the time interval 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 the 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 expected duration of the 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 the first frame that blocks TXOP around the first website in response to receiving this designator; Receive the first frame at AP; And be sent in the second frame that blocks TXOP around the AP in response to receiving the 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 the first website, confirmation of receipt (ACK) frame before receiving the first frame.

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

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

T. a symmetrical transmission opportunity (TXOP) method for cutting comprises: send the first frame at the first website; After the first frame, send extended inter frame space (EIFS) at the first website frame is set; And sending the second frame at the second website, described the second frame has the fully transmission 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 comprises transmission CF-end frame wherein to send the first frame and transmission the second frame.

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

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

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

The method of Y.T, wherein EIFS arranges frame and is comprised 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 the first website with logic configuration, and processor also becomes in response to received frame with logic configuration, is sent in the second frame that blocks TXOP around the 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 the first website, the second website or the 3rd website with logic configuration.

The system of AE.Z, wherein the second frame comprises the address of the first website, the address of the 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 take the second logic configuration as receiving the second processor of the second frame.

The system of AH.AG, wherein the second processor becomes in response to receiving the second frame to be sent in the 3rd frame that the 3rd website blocks TXOP with the 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 personal digital assistant (PDA).

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

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

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

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

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

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

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 in response to receiving this designator, be used for being sent in the device that the first website blocks the first frame of TXOP; And be used for receiving the first frame, and in response to receiving this first frame, be used for being sent in the device that AP blocks the second frame of TXOP.

AU. a symmetrical transmission opportunity (TXOP) truncated system, comprising: the first website, described the first website include the first logic and to send the first frame and send extended inter frame space (EIFS) after the first frame frame are set; And second website, described the second website becomes to send the second frame with the second logic configuration, and described the second frame has the fully transmission 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 the first frame and the second frame each comprise the CF-end frame.

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

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

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

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

BA. a symmetrical transmission opportunity (TXOP) truncated system comprises: be used for sending the first frame and send the device that EIFS arranges frame after the first frame at the first website; And the device that is used for sending at the second website the second frame, described the second frame has the fully transmission 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 the first frame that is addressed in the second website at the first website; And after the first frame, at the first website and the second website transmission extended inter frame space (EIFS) frame is set;

The method of BC.BB wherein sends the 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 one or more executable instructions for the specific logical function of implementation procedure or 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 comprises, 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 fact spirit and scope of the present disclosure.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 the first website blocks TXOP on every side; And

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

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

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

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

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

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

7. method according to claim 1, wherein said the second frame comprises: the address of the address of described the first website, described the second website or the address of the 3rd website.

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

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

10. method according to claim 9 also comprises in response to receiving described the 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 according to 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. method according to claim 1, the described step that wherein sends are included in the time interval of short interFrameGap (SIFS) or the time interval of PCF interFrameGap sends afterwards.

13. method according to claim 1, the described step that wherein receives comprises: receive with network allocation vector NAV duration value, described network allocation vector NAV duration value is included in described the second frame expection and is sent out a period of time afterwards.

14. method according to claim 1, the described step that wherein receives comprises: add that with the duration that equals in fact described frame the physical layer convergence protocol duration that the short interFrameGap SIFS time interval adds the expected duration of the above the second frame receives described frame.

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

From access point (AP) received frame, described access point comprises the designator of the end of TXOP;

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

Receive described the first frame at described AP; And

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

16. method according to claim 15, wherein the described step of received frame comprises receiving data frames.

17. method according to claim 15 also is included in described AP place, confirmation of receipt (ACK) frame before receiving described the first frame.

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

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

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

Block the device of the frame of TXOP around being used for being received in the first website, and be used for being sent in the device that the second website blocks the second frame of TXOP on every side in response to receiving described frame.

21. system according to claim 20, wherein said frame comprises the CF-end frame.

22. system according to claim 20, wherein said frame comprises the CF-end frame of the address with described second website.

23. system according to claim 20, the device that wherein is used for receiving described frame also comprises for the device that is used at customer rs site or access point place receiving.

24. system according to claim 20 wherein also comprises for sending the device of CF-end response frame to described the first website, the second website or the 3rd website.

25. system according to claim 20, wherein said the second frame comprises the address of the address of described the first website, described the second website or the address of the 3rd website.

26. system according to claim 20 wherein also comprises for the device to customer rs site or access point transmission for the device that sends described the second frame.

27. system according to claim 20 also comprises for the device that receives described the second frame at the 3rd website place.

28. system according to claim 27 also comprises in response to receiving described the second frame at described the 3rd website place, is sent in the device that described the 3rd website blocks the 3rd frame of described TXOP.

29. system according to claim 28, wherein said the 3rd frame comprises the address of described the 3rd website.