CN101877670B - Time-division multiple access method of optical fiber network media and traffic control mode applied to same - Google Patents

Abstract

The invention relates to a time-division multiple access method of an optical fiber network media and a traffic control mode applied to same. The time-division multiple access method is mainly characterized in that an MAC (Medium Access Control) protocol carries out access control on network nodes using a same optical fiber by adopting the traffic control mode so that the access right of the network nodes on optical fiber bandwidth can be effectively and reasonably distributed among the nodes so as to solve the problem of inequitable distribution of the access right of the time-division multiple access of an optical fiber network and promote the optical fiber network to be suitable for establishing various application networks, such as a metropolitan area network, a local area network or a subnetwork of a public network, and the like, thereby reducing the cost of network construction and enhancing wideband utilization ratio.

Description

The traffic control mode of time-division multiple access method of optical fiber network media and application thereof

Technical field

The invention relates to the traffic control mode of a kind of time-division multiple access method of optical fiber network media and application thereof; Its effectiveness is making the medium frequency range access right of fiber optic network node; Can effectively and reasonably between node, be distributed; With the unfair problem of distributing of the node frequency range access right that improves fiber optic network, impel time-division multiple visit fiber optic network to be able to be fit to do the usefulness of the sub-network etc. of construction local area network (LAN), intercity net or common network, to reduce network construction cost and to promote the wideband utilization rate.

Background technology

According to Hartley-Shannon theorem (passage/information capacity theorem), the channel capacity of transmission medium is limited by the frequency range and the Signal-to-Noise of its transmission medium that uses.The transmission medium that has high frequency range and high Signal-to-Noise has bigger channel capacity naturally.Compare twisted wire and two kinds of transmission mediums of optical fiber, because the noise of optical fiber is very low, frequency range also exceeds much than twisted wire, causes its channel capacity to be height far beyond twisted wire; Therefore, the transmission construction of communication network in recent years replaces twisted wire with optical fiber step by step.

The nature network ground that medium are shared has high frequency range utilization rate, and because their network topology is very simple, therefore is easy to reach the purpose of reducining the construction costs.Various access control steps such as carrier sense multiple access (Carrier sense multiple access; CSMA), carrier sense multiple access/collision detection (Carrier sense multiple access with collision detection; CSMA/CD), token ring (Token ring), token bus (Token bus) and time-division multiple visit (Time-division multipleaccess; TDMA) or the like; Be used in the network that medium are shared, be used as the access control of network node.

In compunication, present most Local Area Network uses the multiple access agreement of Carrier Sense MultipleAccess/Collision Detection (CSMA/CD) more.The physical layer of this agreement is a twisted wire.Under the various service rapid growth momentums of world-wide web today, enlarge the demand pressure of channel capacity, must grow with each passing day; Physical layer uses the Local Area Network of twisted wire; Receive the restriction of transmission range and frequency range, its development that improves channel capacity is easy not as good as optical fiber, and can be because of the raising of channel capacity; Cause transmission range to shorten the phenomenon of communication quality deterioration.So following Local Area Network physical layer under the tight demand that channel capacity must be quickened to enlarge, changes into optical fiber replacement twisted wire and should be inevitable trend.

Because under the demand of digitized development and service assembly; DQDB network (Distributed-queueDual-bus; Distributed queue dual bus; IEEE 802.6) agreement be suggested in nineteen ninety, as the standard of a kind of LAN that reaches the service assembly purpose (Local Area Networks) or MAN (Metropolitan AreaNetworks).This network is dual bus topology and combines the time-division multiple visit (Time-divisionMultiple Access, TDMA) The Application of Technology provides integrated service.

This network convention tool is integrated the ability of isochronism (being engaged in like voice or multimedia news) and non-isochronous news affairs (like data traffic).Because transmission medium is optical fiber, have the characteristic of low error rate, be fit to the development of high-speed communication service and satisfy the demand of high service quality.This network is adopted the multiple access mode of TDMA; No packet collision problem; Has high frequency range service efficiency, even when the news that network provided are engaged in being higher than channel capacity, still can reach high frequency range service efficiency near channel capacity; And because of in the topology of dual bus, the demand for services of full duplex is reached on this nature network ground.

The DQDB network has as previously mentioned other all Local Area Networks or all can the unexistent use speciality of network; But because of non-instantaneity (non-isochronous) being interrogated media interviews control mode (the Medium AccessControl that is engaged in it; MAC), malapportioned problem is weighed in the media interviews that derive network node.The inequitable assignment problem of access right between this node makes on the fiber optic network of TDMA, and upstream node has the access right higher than downstream node.Therefore cause to be in together under this network, and the frequency range between the user of tool independence uses rights and interests to produce dispute each other.

On each network node (Nodes) of DQDB, when information (Messages) produces, can information be divided into some segments, and, deposit buffer one by one in regular turn with the payload of each segment as unit (Cells), wait transferred.The buffer of intranodal adhere to separately distributed queue (Distributed Queues, DQ) and local queue (Local Queues, LQ) two kinds.Intranodal belongs to the buffer of distributed queue, and the storage length of a unit (53 hyte) is only arranged, and for node data write bus sky is interrogated grooves (slot) before, and the temporary transient position that stores is controlled it by DQSM (DQDB State Mechanism) and write opportunity.Local queue is that then the unit produces temporary position, back, deposits the unit of formation the earliest in, and it is transferred to be moved into distributed queue etc.Unit one gets into distributed queue by local queue, and the sky that is written into bus to this element is interrogated preceding this section period of groove, is called the time of delay (DQ delay) of distributed queue.Unit one to getting into the stand-by period between the distributed queue from local queue, is called the time of delay (LQ delay) of local queue after being produced.The DQ average retardation of one node and the average retardation of LQ, meeting is because of the number of this node in the position of this network (from the distance of news groove generators (Slot Generator)) and the news affair amount that produces thereof, and variation to some extent.This kind cell delay time is aforesaid visit unjust phenomenon along with the situation that node changes from the distance of interrogating the groove generator.

This problem once caused ardent discussion before and after nineteen ninety, a lot of simultaneously control calculation methods are suggested the problem of improving this unfair visit, and these control methods can be divided into two big types according to the improvement strategy of its use.The first kind is the strategy that the news groove re-uses, and second type then is the access control algorithm of improving distributed queue.The news groove re-uses strategy and needs to make the passive node of original part into active node, and the news groove of having been read and write to erase is to increase the available empty news groove number of bus downstream node, through shortening the DQ time of delay of downstream node.And second type of main purpose of improving the access control algorithm is to make the sky that obtains that downstream node can be instant to interrogate groove, and the influence that also need make upstream node not required by the too much transmission of downstream node simultaneously causes interrogating the obstruction of being engaged in.Desire to reach this purpose, then access control algorithm needs to average out between the two in frequency range reservation and frequency range waste.The algorithm of Bandwidthbalancing is adopted in the DQDB MAC agreement of IEEE 802.6, and the mode of reserving with frequency range compensates, to improve the problem of downstream node frequency range visit unjustness.Though the MAC of IEEE 802.6 agreement adopts the algorithm of Bandwidth balancing to reserve the compensation of frequency range; But the problem of visit unjustness is not completely resolved yet; The environment for use of the fair and reasonable distribution of access right can't be provided, give the independent user of shared this network.

The unfairness of this access right is distributed, and influences the delay of each node distribution formula formation of DQDB network.Formation is made up of a plurality of buffer, and so-called " distributed queue " is meant that unit or the buffer of package in the formation are scattered in each node, and as far as the DQDB network, each node has the element buffer of a distributed queue.Each node is used identical MAC agreement, and decision independently of one another is stored in the opportunity that the interior location contents of its distributed queue's buffer is written into the overhead news of fiber buss groove.Though each node is the time of writing out of the element buffer that determines that independently of one another it belongs to distributed queue, applied MAC agreement must be reached the service request of the First-Come-Fist-Serve of distributed queue (FCFS).This characteristic of network utilisation decides each node to use the order of bus transmissioning data; That is to say; Network provides the distributed control of a cover to reach an agreement on and controls distributed queue, makes can more early use the sky news groove on the bus by the node that will transmit data than first to file.

For understanding the characteristic that DQDB node distributed queue postpones; And through solving the unfair problem of distributing of access right; Have several methods to be used to do the analysis of DQDB network, these methods all propose approximate single node analytical model (an approximate single-node analytical model) based on Bisdikian.In this pattern, each node all produces function (thesteady-state generation function) through a stable state and produces " requiring the transmission demand " number that its downstream node is sent to this node when having package to transmit.This node just can determine intranodal to be about to be transmitted distributed queue's delay of package after obtaining this demand number at an easy rate.The analysis result of this kind pattern proves, each node distribution formula queue delay of DQDB network can change along with the difference of node position in network.In brief, existing analytical method is a details of operation of considering MAC, carries out the delay analysis of distributed queue.Because the MAC of DQDB network agreement is very complicated, desire is this medelling of reaching an agreement on, and through accomplishing the queue delay analysis, is a quite thing of difficulty.If desire obtains DQ delay analysis accurately, especially can not reaching of a task through the basis that is operating as of this kind with the MAC agreement.Therefore, this kind analytical method can't be contributed solving the unfair problem of distributing of access right to some extent.

From the angle of TDMA network, the distributed queue on the DQDB network postpones to be equal to the stand-by period on the TDMA network.Stand-by period on the TDMA network is meant the package that intranodal is about to be transmitted, and behind the buffer of linking bus transfer system, is written into bus transfer system idle news groove during this period of time to this package in the entering formation.This definition is identical with the delay that the DQDB network is attend distributed queue.So the DQDB network is attend the delay of distributed queue, with the stand-by period on the TDMA network, both have identical character.If the stand-by period on the TDMA network can be along with network topological change, promptly the average latency of TDMA network node is the function of node location, and then the TDMA network of optical fiber will be the problem that is accompanied by the access right unfair distribution inherently, and both can't cut apart.If the character of above hypothesis can be proved its physical presence, then to fully eliminate the unfair problem of distributing of access right on the DQDB network, will be an impossible thing.On the contrary, if the character of above hypothesis, its existence can't be proved, and after then being analyzed in the stand-by period on the TDMA network, the unfair problem of distributing of access right should obtain suitable solution on the DQDB network.

To a stable TDMA network, and though the MAC that uses agreement for any, the load that network is born should equal the user and require the load that transmits.Therefore, the analysis of stand-by period on the TDMA network can be accomplished through observing the situation that the news groove is used on the tdma system, and need not consider the control operation details of MAC agreement.Planting the observation of tdma system behaviour in service thus can know, the length of the stand-by period of a package on a certain node, and the probability that the news groove that directly can be employed by the next one arrives this node influences.And this probability then can be decided by the news affair distribution of network node and the capacity of transmission medium.

Analysis result shows that the average latency of TDMA node is the function of this node news affair amount.When the power system capacity of TDMA is very big, the average latency of its node and the being inversely proportional to relation of news affair amount that is analyzed node, promptly the news affair amount that transmits of node more greatly, its average latency can be shorter.According to this inference, if MAC agreement has the be engaged in ability of control of news, the average latency of node will with position and the internodal range-independence of node at network.In other words, if on the fiber optic network of TDMA, the operational capacity of its MAC tool news affair control, then the unfair assignment problem of access right just can not exist.

The inventor promptly is in view of above-mentioned analysis situation, proposes the MAC agreement of optical fiber TDMA network, needs to decide the access control of node by interrogating the operation of the control of being engaged in.In other words, the MAC agreement decides the information that stores in the node queue through the operation of news affair control, can be sent to the opportunity of bus, in the hope of the unfair problem of distributing of access right between the node that solves optical fiber TDMA network up hill and dale.

Summary of the invention

Main purpose of the present invention; Provide the traffic control mode of a kind of time-division multiple access method of optical fiber network media and application thereof; The function that its MAC agreement to the effect that needs to use news affair control is accomplished access control; The media interviews powers and functions that just can make fiber optic network are effectively by fair and reasonably between node, distribute; To improve the unfair problem of distributing of optical fiber TDMA network node access right, make this optical fiber TDMA network can be used the construction Local Area Network, all can network or the sub-network of common network or the like, to reduce network construction cost, to promote wideband utilization rate and network service quality.

Description of drawings

Fig. 1 is the configuration diagram of optical fiber TDMA network.

Fig. 2 is corresponding T ₁(n) node average latency curve chart.

Fig. 3 is corresponding T ₂(n) node average latency curve chart.

Fig. 4 is corresponding T ₃(n) node average latency curve chart.

Fig. 5 is the effect curve figure of node interval to the first news affair allocation model.

Fig. 6 is the effect curve figure of node interval to the second news affair allocation model.

Fig. 7 is the effect curve figure of node interval to the 3rd news affair allocation model.

Embodiment

As far as the TDMA network, the node of a tendency to develop carry information must be seen " transmit and require " earlier off and notify whole network, to reserve idle news groove.The free time news groove number of reserving is corresponding to see off the number of " transmit and require ".When the free time of reserving, news groove number became big, its node average latency will thereby reduce.Therefore, if a node has higher news affair amount, its average latency will diminish.If average latency of TDMA node is taken as the standard that its institute of assessment has news groove access right, then the node of the bigger news affair amount of generation will have more access right.In other words, between the TDMA node, how much each is with its vying each other of news affair amount that produced, to strive for the access right of medium.The average latency of this TDMA node and its node news affair amount relation between the two can be derived as follows.

The derivation of the average latency of TDMA node is based on three network operation conditions.First operating condition explanation is in fully loaded situation by phase-split network.Another operating condition limits each " transmission requires " only can reserve an idle news groove.The access control operation of the 3rd operating condition hypothesis node can not limit the transmission number that it " transmits and require ".Because of in this three operating condition, but the access right of arbitrary news groove is striven in all node free competitions.Just one stable and contain the TDMA network of N node, make R represent the speed of interrogating groove on this network-bus, T (n) represents interior n the news affair amount that node produced of network, and wherein n is the sequence number of node, and 0≤n＜N.Then T (n) can represent as shown in the formula:

T(n)＝r(n)/R， (1)

R in the formula (n) is each second, and n node caught, in order to transmit the news groove number of information.

Because of in first operating condition and formula (1), all T (n) with can represent as follows:

$\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}T\left(n\right)=1---\left(2\right)$

From the angle of n node, the news groove on the transmission medium can be divided into three kinds.These three kinds are news groove, the news grooves that has been reserved that has used and freely interrogate groove.The news groove that has used carries the information of upstream node, and the news groove of having been reserved is in order to transmit the information of downstream node, and freely interrogating groove is n the adaptable news groove of node.These are freely interrogated groove and possibly reserved by n node, also possibly not be reserved.In a stabilizing network, freely interrogate the probability that groove appears at n node, should be equal to or greater than the news affair amount of n node.The news affair amount of n node of cause is T (n), and this network also is T (n) for fully loaded so n node captures the probability of freely interrogating groove.

With regard to one with regard to n the data slot that node produced, suppose that this data slot gets into the buffer that is connected bus, get into wait for the situation that is transmitted after, appearing at i of this node, to interrogate groove be freely to interrogate groove.Make p _w(n i) representes that this data slot is written to the probability of i news groove, i=1 wherein, and 2 ..., R, then p _w(n, i) can represent as follows:

p _W(n，i)＝T(n)(1-T(n)) ^i-1 (3)

If represent the maximum latency of n node with M (n).Because n node uses the individual news groove of r (n) each second, then M (n) can represent by following formula:

M(n)＝R-r(n)+1 (4)

With r (n) the substitution formula (4) of formula (1), M (n) can be put in order as follows:

M(n)＝R(1-T(n))+1 (5)

If with the average latency of n node of μ (n) expression.This average latency can computes:

$\mathrm{\μ}\left(n\right)=\underset{i=1}{\overset{M\left(n\right)}{\mathrm{\Σ}}}{\mathrm{ip}}_W(n,i)=\underset{i=1}{\overset{M\left(n\right)}{\mathrm{\Σ}}}\mathrm{iT}\left(n\right){(1-T\left(n\right))}^{i-1}$

$=[1-{(1-T\left(n\right))}^{M\left(n\right)}(1+M\left(n\right)T\left(n\right))]/T\left(n\right)---\left(6\right)$

With M (n) the substitution formula (6) of formula (5), the average latency of n node can be rearranged as follows:

μ(n)＝[1-(1-T(n)) ^R(1-T(n))+1(1+(R(1-T(n))+1)T(n))]/T(n)(7)

If the news groove speed R of network fixes; Formula (7) shows the average latency of n node; Only along with the news affair quantitative changeization of n node, and with node position and each internodal range-independence, more with the no correlation existence of the MAC agreement of facilitating medium to share.

As far as express network, R levels off to infinity.Then the μ on the express network (n) can deduce as follows:

$\underset{R\→\∞}{\lim }\mathrm{\μ}\left(n\right)=\underset{R\→\∞}{\lim }\left\{\right[1-{(1-T\left(n\right))}^{R(1-T\left(n\right))+1}(1+(R(1-T\left(n\right))+1)T\left(n\right))]/T\left(n\right)\}$

$=1/T\left(n\right)---\left(8\right)$

Formula (8) conclusivelys show, and the average latency of a high speed TDMA node is with its node news affair amount relation of being inversely proportional to.In brief, as far as high speed TDMA network, node news affair amount is bigger, and its average latency can be littler.This characteristic shows that consumingly on the high speed TDMA network, the average latency of a node and network topology are irrelevant.In other words, the media interviews of high speed TDMA node power is along with the news affair quantitative changeization of node.Therefore, if its used MAC agreement contains suitable news affair control ability, then the media interviews of this network power can effectively and reasonably be distributed between node.

Because of fiber optic network is the express network of tool high power capacity, so the characteristic of the average latency of aforesaid high speed TDMA node and its node news affair amount relation of being inversely proportional to as far as the fiber optic network of TDMA, is its inherent characteristic.So if the MAC of the fiber optic network of TDMA agreement contains suitable news affair control ability, the media interviews of this network power then can be by the effectively fair and reasonably distribution in the node intercropping.

For confirming and explain above-mentioned invention, the present invention is applied on the time-division multiple visit fiber optic network at this MAC with tool news affair control ability, and conducting interviews is controlled to be example, does explanation and checking.

In order to check the invention effect of optical fiber TDMA network node MAC control method, the hypothesis of some network work conditions is suggested, so that carry out the simulation of optical fiber TDMA network.Fig. 1 is the framework that discloses optical fiber TDMA network.Among the figure, the medium between news groove generator (slot generators) and news groove terminators (slotterminators) are an optical fiber.News concentrated flow on the optical fiber is seen off by news groove generator, sinks to news groove terminator at last.Whole network has N node.All nodes are numbered on the right side by a left side in regular turn.The numbering of each node also can be represented its node location in whole network topology.News groove generator is interrogated the time interval that groove is served optical fiber with one, is called a news groove time.The distance that the news groove extends on optical fiber is called a news slot length.In addition, those are related to the interval of adjacent node, and the condition of work of the distribution that news are engaged between the length of information and node etc. is after being described in.

In the embodiment of a simulation, each equates all that to adjacent internodal interval this is the integral multiple of news slot length at interval.In order to confirm the node average latency, whether can be along with internodal interval variation, the node interbody spacer of simulation embodiment will change along with embodiment, the distribution but original node news are engaged in then remains unchanged.In all simulation embodiment, the length of information remains unchanged, and the length of each information equals a length of interrogating the groove payload.The news of node are engaged in distributing, and influences the variation of node average latency, so be engaged in distributing will be along with embodiment changes news, with the characteristic of " the desirable fair behavior " of checking optical fiber TDMA network.

Be engaged in controlling in order to accomplish news at an easy rate, will use a basic news affair amount, with the basis of the distribution of being engaged in as news.This interrogates the affair amount basically with T _BExpression.T _BAmount, be engaged in distributing by the news of each embodiment and decide.In an embodiment, the news affair amount of arbitrary node is T _BIntegral multiple, in other words, to interrogate the affair amount be T to minimum possible node in the embodiment _BBased on T _BQuote, the news that not only are easy to define on the various optical fiber TDMA networks be engaged in to be distributed, news affair control operation also can cooperate various news to be engaged in distributing to accomplish at an easy rate.

The MAC example of operation that can accomplish news affair control is described below.The MAC operation that news are engaged in controlling is to use news groove frame to accomplish.News concentrated flow on optical fiber is divided into several news groove frames.Each news groove frame contains 1/T _BIndividual news groove.When a news groove frame arrives n node, this node can with its etc. transferred information, the free time that writes continuously in the frame is interrogated groove, the maximum information number that this can write out continuously must be less than or equal to T (n)/T _B, wherein T (n) is the news affair amount of n node.The maximum information number that this can write out continuously before news groove frame arrives, will be loaded into a reciprocal counter.Information number in being stored in formation is greater than T (n)/T _BThe time, the maximum of reciprocal counter will equal T (n)/T _BOtherwise the maximum of reciprocal counter should equal the information number in the formation.Then, whenever see an information off, reciprocal counter subtracts one.Make zero up to reciprocal counter, this node is the transmission of Stop message immediately, and the information that still stores in formation this moment such as needs to arrive at next news groove frame, just can restart next foregoing news affair control cycle.

Whether the purpose that this network analog is carried out mainly at check optical fiber TDMA network, meets the characteristic of " desirable fair behavior ".The optical fiber TDMA network that this is verified need be reached an agreement on the MAC with news affair control ability and done access control." desirable fair behavior " is meant under the situation that does not change node news affair amount, the node average latency of optical fiber TDMA network, can not change along with the relevant position of node in network.This relevant position comprises the position and the internodal interval of node.Therefore, internodal news are engaged in distributing and at interval, must be changed along with the embodiment of simulation.

On the other hand, formula (8) is represented, by analyzing the node average latency that produces, will be used for confirming Simulation result.If with D _RmsThe node average latency root-mean-square error between the two that expression is analyzed and simulated, then D _RmsCan be defined as follows:

$D_{\mathrm{rms}}={\left(\frac{1}{N-1}\underset{n=0}{\overset{N-2}{\mathrm{\Σ}}}{({\mathrm{\μ}}_s\left(n\right)-\mathrm{\μ}\left(n\right))}^2\right)}^{1/2}---\left(9\right)$

μ in the formula _s(n) and μ (n) average latency of representative simulation and n node analyzing gained respectively.

In following all display simulation results' figure, the number of trunnion axis, the sequence number of representation node.Because the sequence number of node is the numeral that disperses, so the curve in all figure is made up of little line segment.Unit in node average latency of the longitudinal axis is with the time representation of news groove.

In order to understand the node news affair amount of optical fiber TDMA network, to the node average latency, reach " desirable fair behavior " and wait both influences, three kinds of news affair allocation models are used in simulation.In these the three kinds news affair allocation models, the news affair amount of each node all is T _BIntegral multiple.Because optical fiber be folk prescription to transmission information, and the information of all nodes is not all seen this analog network off, so in all news affair allocation models, (N-1) individual node all produces news and is engaged in.In first news affair allocation model, make T ₁(n) the news affair amount of n node of expression, then T ₁(n) definable is following:

T ₁(n)＝(N-n-1)T _B，n＝0，1，...，N-2(10)

In this definition, have the news affair amount of maximum near the node of news groove generator.The news affair amount of other nodes reduces along with the increase of node ID.Based on this definition, in a news groove frame, n the seizable maximum news groove number of node is (N-n-1).Because this network is fully loaded, so

$1=\underset{n=0}{\overset{N-2}{\mathrm{\Σ}}}{T}_1\left(n\right)=\underset{n=0}{\overset{N-2}{\mathrm{\Σ}}}(N-n-1)T_B=N(N-1)T_B/2---\left(11\right)$

So corresponding to first news affair allocation model, the contained news groove number (F of news groove frame ₁) be:

F ₁＝1/T _B＝N(N-1)/2 (12)

Root is in first news affair allocation model, and its corresponding simulating result is shown in Fig. 2.The network of this simulation contains 40 nodes.The variation of the node average latency that the solid line representative is got by analytical calculation among the figure, the variation of the node average latency that the dotted line representative is got by simulation.Article two, curve is almost completely heavily built.The root-mean-square error of the node average latency of two curve representatives is calculated as follows;

$D_{\mathrm{rms}}={\left(\frac{1}{N-1}\underset{n=0}{\overset{N-2}{\mathrm{\Σ}}}{({\mathrm{\μ}}_s\left(n\right)-\mathrm{\μ}\left(n\right))}^2\right)}^{1/2}=0.073485---\left(13\right)$

This root-mean-square error value levels off to zero, and this result not only confirms the correctness of this paper to node average latency inference, also confirms the accuracy to optical fiber TDMA network analog simultaneously.

In second news affair allocation model, node news affair amount increases along with node ID in regular turn.Make T ₂(n) represent the news affair amount of n node, T ₂(n) amount can define by following formula:

T ₂(n)＝(n+1)T _B，n＝0，1，...，N-2 (14)

In this definition, minimum near the node news affair amount of news groove generator.The news affair amount of other nodes becomes big along with the increase of node ID.Based on this definition, in a news groove frame, n the seizable maximum news groove number of node is (n+1).The contained news groove of news groove frame is counted F ₂With F ₁Identical, be all (N (N-1))/2.Fig. 3 shows the network with second news affair allocation model, the variation of its node average latency.Solid line and dotted line are represented the variation of analyzing with the node average latency of simulating respectively among the figure.Article two, curve is almost completely heavily built.The root-mean-square error of node between the average latency of two curve representatives is 0.047958.If with n ₁And n ₂The node ID of difference presentation graphs 2 and Fig. 3, the variation to Fig. 2 and Fig. 3 compares again.Comparative result shows: no matter n ₁Whether with n ₂Equate, as long as T ₁(n ₁) and T ₂(n ₂) equate n then ₁With n ₂The node average latency must equate.This phenomenon representes, when the MAC of optical fiber TDMA network agreement, and when having news affair control ability, the average latency of each node, only relevant with the news affair amount of node itself, and have nothing to do with the network site at node place.

From the comparison of above two analog results, can predict that being engaged in when network news is when being evenly distributed, and the average latency of each node, will be equal to each other.For checking this prediction, suppose that the 3rd news affair allocation model is even distribution.Make T ₃(n) represent in the 3rd the news affair allocation model, the news affair amount of n node is then as far as all nodes, T ₃(n)=1/ (N-1)=T _BEach news groove frame includes the individual news groove of K (N-1), and wherein K is a positive integer.In a news groove frame, the seizable maximum news groove number of each node is K.In this simulation, selected K equals 2.Equally distributed news are engaged in distributing analog result such as Fig. 4.

In Fig. 4, solid line and dotted line are represented the variation of analyzing with the node average latency of simulating respectively.Article two, curve is almost completely heavily built.The root-mean-square error of node between the average latency of two curve representatives is 0.003766.The average latency of all nodes much at one.This conforms to prediction result.

Following simulation is in order to inspect the interval between adjacent node, to the influence of node average latency.At three simulation embodiment before, internodal interval all is a news slot length.In the later simulation embodiment, internodal interval all increases to three news slot lengths, and other condition of work is then kept identical with before three embodiment.Fig. 5, Fig. 6 and Fig. 7 correspond to three news affair allocation models respectively, and the internodal analog result that is spaced apart one and three news slot length.

In these three figure of Fig. 5, Fig. 6 and Fig. 7, solid line is represented the interval between adjacent node, is the analog result of a news slot length, and dotted line is represented the interval between adjacent node, is the analog result of three news slot lengths.Article two, curve is almost completely heavily built.Correspond to Fig. 5, Fig. 6 and Fig. 7, the root-mean-square error of node between the average latency of two curve representatives is respectively 0.001235,0.03755 and 0.000176 in every figure.Each root-mean-square error value all levels off to zero.This representation node average latency, not influenced by node size at interval.

Above analog result shows: the MAC agreement has the optical fiber TDMA network of news affair control ability, and its node average latency and network topology are irrelevant.Therefore, through method of the present invention, the media interviews of fiber optic network power can effectively and reasonably be distributed between node, and the inequitable problem of fiber optic network access time that is improved.Optical fiber TDMA network after the improvement be fit to be used construction all can network, the sub-network of Local Area Network or common network, to reduce network construction cost, to promote wideband utilization rate and communication quality.

In sum, the embodiment of the invention really can reach desired use effect, the concrete function that it disclosed again; Not only be not seen in like product, also be not disclosed in application before, really meet the regulation and the requirement of Patent Law fully; So propose the application of patent of invention in accordance with the law; Earnestly ask and give examination, and grant quasi patent, then the true feeling moral just.

Claims (1)

1. time-division multiple access method of optical fiber network media; It is characterized in that; Said method is to make the mode of MAC agreement with news affair control; To the control that conducts interviews of fiber network node, the be engaged in mode of control of wherein said news comprises: the news concentrated flow on the fiber optic network is divided into several news groove frames, and each news groove frame comprises 1/T _BIndividual news groove, wherein T _BThe basic news of representative affair amount, and the news affair amount of each node all is T _BIntegral multiple; When a news groove frame arrives n node, this node with its etc. transferred information, the free time that writes continuously in the frame is interrogated groove, the maximum information number that this writes out continuously must be less than or equal to T (n)/T _B, wherein T (n) is the news affair amount of n node; The said maximum information number that writes out continuously is loaded into a reciprocal counter before news groove frame arrives; Information number in being stored in formation is greater than T (n)/T _BThe time, the maximum of reciprocal counter will equal T (n)/T _BOtherwise the maximum of reciprocal counter should equal the information number in the formation; Then, whenever see an information off, reciprocal counter subtracts one; Make zero up to reciprocal counter, this node is the transmission of Stop message immediately, the information that still stores in formation this moment; Next news groove frame such as need to arrive, just can restart the control of being engaged in of next news.

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