CN1756227A - Method and device for realizing WLAN real-time and QoS - Google Patents
Method and device for realizing WLAN real-time and QoS Download PDFInfo
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Abstract
Disclosed a method for realizing the real-time property and QoS of wireless local network is characterized in that: a QoS intermediate layer is added on the MAC layer of IEEE802.11 which is processed by the software; said QoS intermediate layer can supply the real-time property and QoS to the service. Since said QoS intermediate layer is realized by the software of MAC layer of IEEE802.11 without changing the protocol of IEEE802.11, while it applies present protocol of IEEE802.11 and the future improved protocol of IEEE802.11. The former protocol of IEEE802.11 has worse function of classifying the priority level which only defines two services of real-time (non-completing) and completing, without classifying the priority level on the real-time service. But the inventive method supplies classifying priority level on the real-time service for meeting the application demand to mark the priority level on the service.
Description
Technical field
The present invention relates to WLAN (wireless local area network), the real-time and the QoS that relate in particular to WLAN (wireless local area network) ensure.
Background technology
Along with microelectronics and development of wireless communication devices, wireless lan (wlan) more and more is subjected to people and payes attention to, particularly 1997 WLAN (wireless local area network) international standard IEEE802.11 (IEEE Std 802.11-1997 Information Technology-telecommunications And Information exchange Between Systems-Local And Metropolitan Area Networks-specific Requirements-part 11:Wireless Lan Medium Access Control (MAC) AndPhysical Layer (PHY) Specifications.) pass, promoted the fast development of WLAN.WLAN is not fettered by cable, and is removable, can solve the problem that difficult wiring in the cable network etc. is brought, and networking flexibility is arranged, and dilatation is convenient, and plurality of advantages such as applied range have obtained widely and used.
Analyze for network traffic characteristics, following three kinds of different business are arranged.The first kind is sudden real time business, as real time control command in mistake indication alarm, the home network or real-time data re-transmission etc., the generation of this class real time data is difficult to predict, relevant with the actual operating state of system, the time that occurs is uncertain, and it requires information can pass to destination node as quickly as possible, and the time delay of permission is very little usually, and information can not lose, and the priority of common this data is the highest.Second class is the periodicity real time business, as digital video speech business etc., in system,, has predictability to occur certain cycle time, it requires often low than sudden real time business to network transfer delay, even can tolerate that when channel busy partial information loses.But long time delay or partial information are lost direct traffic affecting quality, and generally periodically the priority of real time business is lower than sudden real time business, and different periodicity real time business also have prioritization.More than two class data all have time-constrain, be called real time data, these class data must be sent to destination node from source node in generating at the appointed time, otherwise are considered as losing or being rendered as hash.The 3rd class is a non-real-time service, for example common Internet business etc., and the transmission of this class business does not have specific (special) requirements for the time, and priority is minimum.The very important point is the real-time and the priority that will guarantee professional transmission in the qos policy of WLAN, and it is corresponding to have the strategy that adapts at dissimilar business.
IEEE802.11 has the two media access control scheme: the center coordination mode (PointCoordination Function, PCF) and the distributed coordination mode (DistributedCoordination Function, DCF).In the IEEE802.11 media access control protocol, time-domain is divided into the form of superframe, and superframe was made up of contention free period and competition phase, and wherein contention free period is optional.In the contention free period of superframe, (Access Point AP) carries out poll, and a certain moment only allows a node to send by center control nodes.And, support the asynchronous transmission business with the competition access way in the competition phase of superframe.In order to support priority service, IEEE802.11 distinguishes different priority with different frame gaps.The node detection that priority is high waits for that the short time gets final product proceed-to-send signal after channel idle, delivery time is prior to other low priority node, other low priority node finds to have had on the channel other signal in transmission after waiting for the idle time of channel of stipulating separately, so the transmission that stops separately being attempted, priority node can preferentially obtain channel by this method.IEEE802.11 has stipulated other frame gap time of three levels, be respectively Shortinter-frame space (SIFS), Point-coordination functioninterframe space (PIFS), Distributed coordination functioninterframe space (DIFS), SIFS is the shortest frame gap, to in requisition for the business that makes an immediate response, as ACK answer signal etc.The access way of the corresponding PCF of PIFS, the access way of the DCF of the corresponding non real-time signal competition of DIFS, blanking time is also the longest.
Center coordination mode (PCF) is an optional media access control method among the IEEE802.11, is mainly used in the transmission of live signal.As shown in Figure 1, AP sends request signal to the node that participates in uncontested business.If the node that is polled to has data to send, wait for that then a SIFS sends data after the time interval immediately, otherwise keep silent.After AP sends polling signal, if do not receive any response in the time at PIFS, AP will recover the control to channel so, send next poll frame, participate in all polled one time of the node of uncontested transmission until all.Though IEEE802.11 declares and can provide the real-time Data Transmission service with the center coordination mode that practical application is unsatisfactory.If IEEE802.11 is applied to real-time service transmission, all real time business all are mapped as the uncontested service of PCF mode among the IEEE802.11, by the polling mode allocated channel, different real time business can not embody the priority difference in the contention free period of superframe.And the number of the node of transmission data is uncertain with the time that takies in the contention free period, and the transmission time of PCF is uncertain, might cause some business not obtain access control power within cycle of stipulating or maximum delay scope.PCF also has some other deficiency, comprises that the transmission delay of signal when polling mechanism causes the channel underload is long etc.For these reasons, PCF is not widely used, in fact this function (Principles of Wireless Networks is not realized in most manufacturing commercial city in their product, Kaveh Pahlavan, the PrashantKrishnamurthy work, Liu Jian etc. translate, publishing house of Tsing-Hua University, 2002.), that is to say that most IEEE802.11 product is only to have realized DCF.
Distributed coordination mode (DCF) is with the competitive way allocated channel, and all nodes are the access control power of competitive channel freely, and its basis is CSMA/CA and random back algorithm, as shown in Figure 2.When node detection to channel idle and free time during greater than DIFS, begin to send Frame, otherwise adhere to entering the back-off wait state according to back off algorithm.CSMA/CA can't depend on collision detection and determine whether transmission success, so reply confirmation signal is very necessary in transmission, if in official hour, sending node does not receive the acknowledgement frame signal, just thinks that admission control and preparation retransmit this Frame.DCF is a kind of perfect competition distributed medium access control method, and agreement is simple, flexible, reliability is high, still without any the prioritization of type, does not provide the real-time support.When network load was light, the conflict of Frame was fewer, and network transfer delay is short, embodies good performance.But when network load was heavy, the possibility that the conflict of Frame retransmits increased, and a large amount of bandwidth resources are wasted in the competition of channel and retransmit.And different with CSMA/CD be, CSMA/CA can't depend on collision detection and determine whether transmission success, after node sends Frame, even occurred conflict on the channel, sending node also can't be known, whole Frame can only be sent and finish, by the time the stand-by period upper limit of regulation and do not receive that the acknowledgement frame signal knows that just channel confliction is arranged.The time of channel confliction increases greatly like this, and has increased for the time delay that is used to compete is also corresponding.
From the above description as can be seen, IEEE802.11 is for the support of real-time service and bad, and channel load is heavy the time, because competition causes channel efficiency low.But along with the extensive use of WLAN, a lot of application requirements WLAN provide better real-time property and priority support with limited bandwidth, and service quality seems more and more important in 802.11 networks.IEEE has proposed 802.11e recommended standard draft (IEEE Std.802.11e/D3.0, IEEE Draft Standard for Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications, Medium Access Control (MAC) Enhancements for Quality of Service (QoS) .), it has defined the QoS mechanism of supporting the bandwidth sensitive application for wireless device.IEEE has advised that in 802.11e the function that strengthens these two kinds of coodination modes supports QoS.The DCF mechanism of original IEEE802.11 is enhanced, i.e. enhanced distributed coordination function (EDCF) has been introduced the notion of transport stream kind.Each radio node has 8 kinds of transport stream kinds, i.e. priority.When using EDCF, radio node sends data again after detecting idle condition and waiting for a period of time of respective transmissions stream class regulation.After node with lower priority transport stream must be waited for the longer time than those nodes with high priority transfer stream, access of radio network again.In order to reduce the transport stream conflict of same priority, outside 8 priority, also have an extra Control Parameter, be called competition window, its length is by a random number decision of constantly successively decreasing.The free time that radio node is waited for regulation at interval after, the competition window that also necessary stand-by period length is determined at random, if during this period of time detecting other node sends, this node have to be waited for the next channel idle period, but the random number of decision contention window size then subtracts from the surplus value of last time.EDCF does not provide the certainty service guarantees, but has set up a kind of preference for probability mechanism of distributing bandwidth according to the transport stream kind.On the other hand, 802.11e has defined hybrid protocol function (HCF) and has attempted to expand the PCF polling mechanism.A mixture control is at competition phase poll radio node.Poll is given a time started an of radio node and a maximum transmitted duration.802.11e provided the solution of preliminary WLAN (wireless local area network) QoS, arriving aspect real-time and priority support improves, but EDCF provides just preference for probability level mechanism, can not provide deterministic priority to guarantee, and HCF is also few just as the support that present PCF obtains.And IEEE802.11e only is a draft now, the approval that does not also have to the end, and the product of the QoS of the feasible WLAN of support delays to occur.Even be given the ratification by, existing a large amount of IEEE802.11 products are not supported new agreement yet, so current problem is how to allow current WLAN support QoS, and need not change existing product and agreement.
Summary of the invention
The objective of the invention is to realize allowing current WLAN support QoS better, and need not change existing wlan product and agreement.
According to the present invention, on the MAC of IEEE802.11 layer, add a protocol layer, be called the QoS intermediate layer, this layer is by the software realization, as shown in Figure 3.This layer main purpose be solve the IEEE802.11 real-time service and do not have that prioritization, real-time guarantee are not enough, the low inferior problem of channel efficiency during heavy load, effective QoS mechanism promptly is provided.Different qos policys is carried out for different business in the QoS intermediate layer, as shown in Figure 4, carries out further prioritization service for real time business; Business to high priority provides the guarantee of maximum transmitted time delay; Insert by the node of admitting control restriction low priority, thus the QoS of assurance high-priority service; According to the stagger contention access of node competition time or restriction node of channel load situation, this is an adaptive strategy, can prevent the overweight network congestion that causes of channel load, makes the overall performance optimization of network.The realization in QoS intermediate layer without any influence, does not just need to do any change for existing IEEE802.11 product for the MAC layer of IEEE802.11.
The present invention be directed to the improvement of prior art, it provides a kind of real-time of WLAN (wireless local area network) and method of QoS of realizing, it is characterized in that, adds a QoS intermediate layer on the MAC of IEEE802.11 layer, and this layer is realized by software; This QoS intermediate layer provides real-time and QoS to business.
By the present invention,
(1) software on the MAC layer that is IEEE802.11 of this QoS intermediate layer is realized, does not change the agreement of IEEE802.11 fully, is applicable to existing IEEE802.11 agreement, also is applicable to the improvement of IEEE802.11 in the future.Be applicable to the IEEE802.11 product on the present market fully, embody favorable compatibility and adaptability.
(2) original IEEE802.11 protocol architecture prioritization function is very weak, has only defined real-time (non-competing) and two kinds of business of competition, does not further distinguish priority for real-time service.And increasing application requirements carries out further priority tag for business, and the present invention provides the prioritization service to real-time service.So that Differentiated Services better to be provided.
(3) provide the maximum transmitted time delay to guarantee for high-priority service, particularly when channel load is heavy, can give high-priority service the channel priority allocation.
(4) provide admittance control, when node has the periodicity real time business to transmit, need file an application to AP, AP determines whether to admit application according to factors such as request priority, the network bandwidths.When network load is heavy, controls the low business application of restricted part priority by admitting, thereby guarantee the QoS of high-priority service.
(5) dynamically change the number, access service kind etc. of access node according to network channel situation, QoS of survice etc., dynamic self-adapting changes can in time guarantee high-priority service QoS, guarantees the channel high efficiency.
(6) according to channel variation, the competition of a period of time of restricted part node prevents the overweight obstruction that causes of channel load.In the time of light load, keep the high efficiency and the low delay character of original competition network.And in the time of heavy load, reduce the possibility of conflict, and raise the efficiency, improve the utilance of channel.
Description of drawings
Fig. 1 represents the media access control method of the center coordination mode (PCF) among the IEEE802.11.
Fig. 2 represents the media access control method of the distributed coordination mode (DCF) among the IEEE802.11.
Fig. 3 represents the schematic diagram according to protocol hierarchy of the present invention.
Fig. 4 represents according to QoS interlayer structure block diagram of the present invention.
Fig. 5 represents according to QoS of the present invention intermediate layer data packet format.
Fig. 6 represents to have according to the present invention the Qos intermediate layer periodicity real time business process of transmitting of PCF support.
Fig. 7 represents to have the sudden real time business process of transmitting in Qos intermediate layer of PCF support.
Fig. 8 represents not have according to the present invention the Qos intermediate layer periodicity real time business process of transmitting of PCF support.
Embodiment
A), QoS data packet format
As shown in Figure 5, the QoS bag is made up of packet header and data field, and packet is divided into two kinds: controlling packet and effective data packets, distinguish by packet header.Controlling packet is used for management control etc., for example admits control etc., is produced and termination by the QoS layer.And effective data packets is held the valid data that have on the upper strata, gives the MAC layer after the packing; Receive the data of MAC layer simultaneously, give the upper strata after unpacking.
B), at the IEEE802.11 product that has PCF to support
PCF provides certain real-time guarantee, and the major function in QoS intermediate layer is that the prioritization service further is provided, and by admitting the control limiting access, prevents that channel load is overweight.The QoS intermediate layer with sudden real time business and periodically real time business be mapped to the contention free period transmission of the superframe in the MAC layer of IEEE802.11, non-real-time service is mapped to the competition phase transmission of the superframe in the MAC layer of IEEE802.11.
The periodicity real time business
Definition provides prioritization for the periodicity real time business, and the requirement in the QoS of the business of different priorities, time delay, cycle is all different.Periodically real time business all is the contention free period transmission that is mapped to the superframe in the MAC layer.For IEEE802.11, being mapped to superframe contention free period business is not add differentiation, causes some business, or even high-priority service, might not visit within cycle of stipulating or time delay scope.So the QoS intermediate layer must provide accommodating control function.
Periodically real time business sends needs through application, and the application frame comprises time started, priority, time cycle, maximum delay, bandwidth requirement etc. by proposing in the contention free period, waits for replying of AP then.Node is only received and just can be determined to begin communication behind the signal of replying, and periodically the real time data bag adds that packet header gives MAC layer, is ready for sending with live signal.Otherwise can not submit data to the MAC layer, even upper layer application has periodic data to generate, the temporary transient buffered data in QoS intermediate layer, application again after only waiting for a period of time.
The field that comprises of application frame is as follows, wherein,
Time started: when indication begins periodically real-time service transmission.
Priority: set priority according to business importance, when channel load was heavier, whether AP admitted application according to priority size and channel load decision.
Time cycle: periodically the data of real time business produce the cycle.
Maximum delay: in patient maximum wait time delay of the transmission stage of data.Time cycle and maximum delay have determined the length of contention free period and superframe, and just how long poll is once.
Bandwidth requirement: the size of each packet influences the length of channel occupancy time and contention free period.
AP is according to the priority, needed bandwidth, cycle of application, current channel conditions etc., and whether decision admits application or refusal.Basic principle is: under the enough situation of bandwidth, admit the periodically application of real time business as far as possible; When bandwidth is not enough, the priority of relatively application business and the priority of current transport service, if the professional priority height of application admits application to interrupt the transmission of current low priority simultaneously so, to guarantee the business of limited bandwidth service, exclude so if the application service priority is low in high priority.The response message of whether admitting is to tell the applicant in the contention free period of next superframe.The every startup superframe of AP all will calculate in the zero hour and the finish time of the interim periodic signal that will send of this transmission according to current application information, and the corresponding acknowledgement frame response time need be taken into account, thereby has determined the length of superframe and the length of contention free period.
Admit or the process of refusal is dynamic, if bandwidth is not enough, such as the channel variation, the application of higher priority etc. is arranged, AP can stop current connection.Same when channel width increases, can increase business at any time again.
Sudden real time business
Sudden real time business does not have predictability, can't adopt similar application mechanism.The burst real time business generally is the control signal of weak point etc., and the duration is shorter, but the real-time that requires is generally very high.Be mapped to the contention free period transmission of the superframe in the MAC layer of IEEE802.11 for sudden real time business, generate the back and send at once.Sudden real time business generally is short frame, be very little for the influence of periodic traffic, and influence just is confined within one or two frame.
Non-real-time service
The front has stipulated that AP sets superframe length and contention free period length according to the application of periodicity real time business, has in fact also just determined to be used for the contention free period length of non-real-time service.Under the actual conditions, because factor affecting such as sudden real time business or channel noise, contention free period may be expanded, and the phase that constitutes competition shortens.Just, under the prerequisite that guarantees real-time service transmission,, just distribute to other and be used for the non-real-time service competition if also have bandwidth.
C), the IEEE802.11 product of supporting at no PCF
Present most of IEEE802.11 product does not provide the PCF function, and media access control layer is exactly perfect competition, and the relation between the node is complete equality, and its real-time and QoS are without any assurance.Competitive network in the time of light load, the bandwidth efficiency height, the conflict possibility is little, time delay is short, and in the time of heavy load, conflict is serious, bandwidth availability ratio is low.So our main task is in heavy load, provide and admit control or relevant scheduling, the interstitial content that restriction participates in the competition, thus reduce conflict, limited bandwidth preferentially is used for the transmission of real time data.
It is big to detect load at AP, and conflicts and wait for a long time, sends control frame, limits the non-real-time service quantity of same race visit.The a certain period has only part of nodes can participate in the non-real-time service competition, and the node that participates in the competition is few, and also just having reduced conflict may.If it is quite serious to load, the effect of this measure may be that the non-real-time data of all nodes all can not send, and has only real time data transmitting.If the transmission of real time data still causes a large amount of conflicts, AP sends signal and informs that low some period of real time data of priority of part stops transmission so, leaves channel for high-priority service.This method can not provide real-time to guarantee service on the basis of DCF, but certain prioritization service can be provided, and can effectively improve channel utilization especially when channel load is overweight, prevents too much conflict and obstruction.
Embodiment
The present invention is described in further detail below in conjunction with the accompanying drawing illustrated embodiment.
A), QoS data packet format
In this embodiment, header field is 00, and then indicating this QoS bag is controlling packet.Controlling packet is used for management control etc., for example admits control etc., is produced and termination by the QoS layer.
When header field is 11, then indicating this QoS bag is effective data packets.And effective data packets is being carried the valid data that the upper strata is come, and gives the MAC layer after the packing; Receive the data of MAC layer simultaneously, give the upper strata after unpacking.
B), at the embodiment of the IEEE802.11 product that has PCF to support
The periodicity real time business
Definition provides prioritization, P for the periodicity real time business
i(i=0,1 ... n.Periodically real time business all is the contention free period transmission that is mapped to the superframe in the MAC layer.Below, contrast Fig. 6 describes the periodically transmission flow of real time business.
Periodically real time business arrives node, the data buffer area (step S100) that at first enters the QoS intermediate layer.Periodically real time business sends needs through application (step S101), and the application frame comprises time started t by proposing in the contention free period
Start, priority p
m, period of time T
p, maximum delay T
Max delay, bandwidth requirement l
PackeiDeng, wait for replying of AP then.
AP safeguards the information and the superframe information of the current real time business of having applied for.
Super frame period T
FrameBe once competition phase and the contention free period time span summation of AP, when system initialization, be set at T
Frame0, then according to constantly adjusting the requisition cycle of real-time cycle business,
Method of adjustment is:
If T
p＜T
Frame, T then
Frame=T
p, the purpose of doing like this is that the length of superframe can not be greater than the minimum period of periodic traffic.
AP safeguards the one-period service order form, and just all periodic traffic are all applied for registration of at AP.Field comprises:
Ta
Starti, the time started of the professional i of indication one-period.
Corresponding bandwidth requires ta
Requiementi, comprise data packet length own, IFS interval, ACK response message etc.
Period of time T a
Pi: periodically the data of real time business i produce the cycle.
AP receive the application frame after (step S200), need judge whether to admit this application.The principle that AP admits for the application of periodic traffic is: under the enough situation of bandwidth, admit the periodically application (step S201) of real time business as far as possible.
Otherwise flow process forwards step S202 to, the priority of relatively newer application business and original business.
When bandwidth is not enough, the priority of relatively application business and the priority of current transport service, if the professional priority height of application admits application to interrupt the transmission of current low priority simultaneously so, to guarantee the business of limited bandwidth service, exclude so if the application service priority is low in high priority.Assumption period real time business v is that the priority of current all real-time period business is minimum.
If, P
m≤ P
v, explanation is the priority that the professional priority of application is not higher than current business of having applied for, AP excludes (step S206) so.
Otherwise, if P
m＞P
v, just the professional priority of application is higher than the priority when previous or some business of having applied for.If,
The professional v (step S203) of property interrupt cycle then, and admit new business (step S204).Otherwise, and the like the priority of new business and other written business relatively, admitted (step S204) or be rejected (step S206) because priority is not enough up to this new business.
The node of the new periodically real time business of application is judged the acknowledgement frame (step S103) of whether receiving AP in the official hour interval.If do not receive acknowledgement frame, then forward step S111 to, wait for a period of time at interval, restart to send application frame (step S101).If receive acknowledgement frame at interval at official hour, then forward step S104 to and judge it is to agree or exclude, if AP excludes, the back (step S112) of then waiting for a period of time resends application frame (step S101).Otherwise flow process forwards step S105 to, and data map is become the contention-free period real time business, waits for that the polling signal of AP sends.If in process of transmitting, receive the indication of the interrupting service of AP, illustrate that bandwidth need give the business of higher priority, flow process forwards S108 to, and node stop sends data, wait for a period of time then (step S109), application continues to send (step S110) again.
Admit or the process of refusal is dynamic, if the channel variation, use the same method can interrupts low-priority business and ensure the transmission of high-priority service.Same when channel width increases, can increase business at any time again.
Sudden real time business
Sudden real time business transmission flow such as Fig. 7 describe.When sudden real time business arrived, data were at first put into buffer area high-priority queue (step S100), and data map becomes non-competing business (step S101), sent Frame (step S102) behind the polling signal of wait AP.If receive acknowledgement frame in the official hour interval, then flow process forwards step S104 to, restarts to send otherwise forward S101 to.Judging whether it is to confirm acknowledgement frame at step S104, is then to forward step S105 to continue to send, and resends Frame otherwise forward step S101 to.
C), the embodiment of the IEEE802.11 product of supporting at no PCF
Bandwidth application and distribution at the real-time period business all are just the same with the periodicity real time business transmission flow that has PCF to support mentioned above, after just AP will distribute to different nodes the time period, notify all nodes in the mode of broadcast frame, other node can not send Frame in the time period that has kept like this, in the time period of distributing, have only a node sending, can not constitute competition.
Comparison diagram 6 (have PCF support) and Fig. 8 (no PCF support), sending node is a step S105 difference, Frame is mapped in the contention free period to send in the official hour interval.For AP, increase step S205 and send broadcast frame notice node reserved bandwidth.
Sudden real time business is as long as arrive, and is put into the high queue of priority levels of buffers, is mapped to the shortest time that contention free period is professional to be sent.
The remaining non-retention time section of non-real-time service competition, the business of node i is mapped to the contention free period business with the Pri probability from the formation of buffering area, stay buffering area with the 1-Pri probability.
Pr
i=(1-P
Con) α
i(t), wherein is a weight factor, P
ConDescribe congestion situation, be defined as the total transmission number of times in the conflict number of times/unit interval in the unit interval.α
i(t) be and the time correlation factor, default value is 1.
Like this, it is big to detect load at AP, and conflicts and wait for a long time, and AP has two kinds of regulating measures.The conflict increase causes P
ConBecome big, Pri reduces like this, and each node reduces Frame and sends the reduction conflict.Simultaneously, AP distributes different α for different nodes
i(t), limit the number of nodes of same race visit.The a certain period has only part of nodes to participate in the competition, and the node that participates in the competition is few, and also just having reduced conflict may.The simplest method is the same time period, the α of half node
i(t) be 1, remaining α
i(T) be 0, limited half node and participated in conflict, but be not limited to this method.
Participate in the competition if limited non-real-time service, channel load is still serious, can adopt the periodic traffic of the restriction low priority that uses the same method and the sudden real time business of low priority and participate in channel competition, abdicates bandwidth and gives high-priority service.
Below embodiment has been described in detail the present invention in conjunction with the accompanying drawings, and those skilled in the art can make the many variations example to the present invention according to the above description.Thereby some details among the embodiment should not constitute limitation of the invention, and the scope that the present invention will define with appended claims is as protection scope of the present invention.
Claims (16)
1. realize the real-time of WLAN (wireless local area network) and the method for QoS for one kind, it is characterized in that,
Add a QoS intermediate layer on the MAC of IEEE802.11 layer, this layer is realized by software;
This QoS intermediate layer provides real-time and QoS to business.
2. according to the method for claim 1, it is characterized in that this QoS intermediate layer comprises control module, be used to carry out the management control in QoS intermediate layer; Data cache module is used for according to type of service and/or service priority business being carried out buffer memory; Packet ground encapsulation and decapsulation module are used for data are packed or unpacked.
3. according to the method for claim 1, it is characterized in that having control data bag and effective data packets in this QoS intermediate layer, this control data bag is used for management control and is produced and termination by the QoS intermediate layer, this effective data packets is being carried the valid data that the upper strata is come, and gives the MAC layer after the packing; Receive the data of MAC layer simultaneously, give the upper strata after unpacking.
4. according to the method for claim 2, it is characterized in that,
Prioritization is carried out for the periodicity real time business in this QoS intermediate layer.
5. according to the method for claim 4, it is characterized in that,
When node has the periodicity real time business to transmit, file an application to AP, judge whether to admit this application to allow to transmit this periodicity real time business by AP.
6. according to the method for claim 5, it is characterized in that AP judges whether to admit the mode of this application to be, under the enough situation of bandwidth, admit the periodically application of real time business; When bandwidth was not enough, the priority of relatively application business and the priority of current transport service if the professional priority height of application admits application to interrupt the transmission of current low priority simultaneously so, excluded so if the application service priority is low.
7. according to the method for claim 5, it is characterized in that AP judges whether to admit the mode of this application to be,
If
Wherein,
Ta
RequiementiBe the bandwidth requirement of current period real time business i,
Ta
PiThe data that are current period real time business i produce the cycle,
T
pBe the time cycle of the periodicity real time business of application,
Ta
Requie mentBe the bandwidth requirement of the periodicity real time business of application,
T
FrameBe super frame period,
Then can admit,
Otherwise if the priority of relatively application business and the priority of current transport service are the professional priority height of application, then admit application and interrupt the transmission of current low priority, so that bandwidth is used for the business of high priority, exclude so if the application service priority is low
Assumption period real time business v is that the priority of current all real-time period business is minimum,
If the priority of the periodicity real time business of application is smaller or equal to the priority of current period real time business v, AP excludes so,
Otherwise, if the priority of the periodicity real time business of application, applies for just that professional priority is higher than the priority when previous or some business of having applied for smaller or equal to the priority of current period real time business v, if,
8. according to the method for claim 5, it is characterized in that,
For the center coordination mode, periodically real time business is mapped to the non-competing phase transmission of the superframe in the MAC layer.
9. according to the method for claim 5, it is characterized in that,
For the distributed coordination mode, after the periodicity real time business of application was admitted, AP distributed the time period to give the periodicity real time business of this application, and notifies all nodes, other node can not send Frame in this time period, have only a node sending in the time period of distributing.
10. according to the method for claim 2, it is characterized in that,
For the center coordination mode, sudden real time business is buffered to highest-priority queue, is mapped to the non-competing phase transmission of the superframe in the MAC layer with the shortest time.
11. the method according to claim 2 is characterized in that,
For the distributed coordination mode, sudden real time business is buffered to highest-priority queue, is mapped to competition phase business with the shortest time.
12. the method according to claim 1 is characterized in that, provides the guarantee of maximum transmitted time delay for sudden real time business.
13. the method according to claim 1 is characterized in that, according to the channel load situation number of nodes that node competition time or restriction participate in the competition that staggers.
14. the method according to claim 13 is characterized in that, for the business of competition phase, the business of node i is mapped to the competition phase with the Pri probability from the formation of buffering area, stay buffering area with the 1-Pri probability, Pr
i=(1-P
Con) α
i(t), wherein is a weight factor, P
Con, be defined as the total transmission number of times in the conflict number of times/unit interval in the unit interval, α
i(t) be the time correlation factor.
15. the node apparatus in the WLAN (wireless local area network) comprises interface arrangement at least, processing unit and storage device is characterized in that,
This device is worked in such a way,
Add a QoS intermediate layer on the MAC of IEEE802.11 layer, this layer is realized by software;
This QoS intermediate layer provides different real-time and QoS for different business.
16. the access node device in the WLAN (wireless local area network) comprises interface arrangement at least, processing unit and storage device is characterized in that,
This device is worked in such a way,
Add a QoS intermediate layer on the MAC of IEEE802.11 layer, this layer is realized by software;
This QoS intermediate layer provides different real-time and QoS for different business.
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| WO2009003320A1 (en) * | 2007-07-05 | 2009-01-08 | Alcatel Shanghai Bell Company, Ltd | A method and device for controlling synchronous transmission of service data packet in base station and repeaters |
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| CN104009936B (en) * | 2014-05-21 | 2017-12-01 | 邦彦技术股份有限公司 | Queue scheduling method based on dynamic weight calculation |
| CN111294148A (en) * | 2019-06-06 | 2020-06-16 | 展讯通信（上海）有限公司 | Signaling transmission and receiving method and device, storage medium and terminal |
| CN113812106A (en) * | 2019-06-18 | 2021-12-17 | 索尼集团公司 | Immediate retransmission scheme for real-time applications |
| JP2022536536A (en) * | 2019-06-18 | 2022-08-17 | ソニーグループ株式会社 | Immediate retransmission scheme for real-time applications |
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| JP7393299B2 (en) | 2020-05-22 | 2023-12-06 | 日本電信電話株式会社 | Wireless communication system, communication method, and wireless base station |
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