CN101945430A - Time sensitive transmission and bandwidth optimization utilization-based method used under IEEE802.15.4 network environment - Google Patents

Abstract

The invention discloses a time sensitive transmission and bandwidth optimization utilization-based method used under an IEEE802.15.4 network environment, which comprises the following steps of: firstly, considering a time period Di of transmission data of different nodes and time ED (i) occupied by transmission; and secondly, allocating GTS for each node, reallocating GTS (UGTS) which is not used in the last scheduling process by an effective method, and improving the GTS utilization rate so as to improve the bandwidth utilization rate. The method has the advantages of good performance in the process of transmitting time sensitive service and convenient implementation at a user terminal.

Description

Utilize method based on time-sensitive transmission and bandwidth optimization under a kind of IEEE802.15.4 of being used for network environment

Technical field

The present invention relates to wireless interface technology, administrative mechanism, the mac-layer protocol of IEEE 802.15.4 network, relate in particular to its dispatching algorithm.

Background technology

Along with steady development of economy, people are increasing to the research interest of the IEEE 802.15.4 network of low energy consumption, low rate, because it has very big application prospect at aspects such as military affairs, mining site, home automation and medical treatment nurses.

A complete IEEE 802.15.4 network is made up of several or a plurality of piconets (piconet).Piconet is made up of a plurality of separate nodes, can be further divided into host node and from node, host node can be simultaneously and 7 active in node realization exchanges data.These piconets can interconnect, thereby form more massive decentralized network (scatternet).The application of frequency modulation technology can allow node in the IEEE 802.15.4 network in the highdensity existence of certain intra-zone.

How setting up a good IEEE802.15.4 network of high bandwidth utilization, low delay, low energy consumption and network robustness is the most challenging difficult problem that people study this network.These difficult problems include: the research of the foundation of IEEE 802.15.4 network topology structure, the research of algorithm network routing, network handoff algorithms and the research of network scheduling algorithm.In order to address the above problem, people are carrying out deeply and extensive studies, and with in the achievement in research application that is applied to actual life step by step.The present invention studies the dispatching algorithm of IEEE802.15.4 network emphatically.

The radio-based electronic devices that the necessity of the Study of Scheduling of IEEE 802.15.4 network mainly is all is low-power, low rate because of most IEEE802.15.4 network node, and generally all be the injection frequency.It can only can only be worked in certain special channel in a certain concrete moment with time division multiplexing mode (TDMA) access wireless channel.At this moment, in a huge WPAN network, have under the situation of numerous communication request, the existence of the dispatching algorithm of high bandwidth utilization, low delay is the basic assurance of this network stabilization work.

Present stage, people mainly are to study several aspects to the dispatching algorithm of IEEE 802.15.4 network: 1, low time delay; 2, high bandwidth utilization; 3, fairness is good; 4, Qos guarantees; 5, safe.

Summary of the invention

The objective of the invention is to propose a kind of, optimize the dispatching algorithm of bandwidth availability ratio simultaneously based on time-sensitive transmission.This algorithm is respectively dispatched selection from node to the basis of delay requirement fully satisfying, and by to the redistributing of UGTS, reaches the raising bandwidth availability ratio thereby improve the GTS utilization rate.

The objective of the invention is to realize in the following way: utilize method based on time-sensitive transmission and bandwidth optimization under a kind of IEEE802.15.4 of being used for network environment:

I, the time limit value fine setting:

The given one group of data that need transmit are according to T _i(d _i, p _i, r _i), d wherein _iBe the time limit value of transmission, p _iBe the total amount of data of needs transmission, r _iBe distance from node to bunch head.At first need to the time limit value finely tune, its fine setting after value defined be D _iD _iComputing formula as follows:

$D_i=\left\{\begin{array}{cc}\left(\right[d_i/\mathrm{BI}]-1)\mathrm{BI}+\mathrm{CFP}+\mathrm{CAP}& \mathrm{if\; k}\&GreaterEqual;\mathrm{CAP}+\mathrm{CFP}\\ \left(\right[d_i/\mathrm{BI}]-1)\mathrm{BI}+k& \mathrm{if\; k}>\mathrm{CAP\; and\; k}<\mathrm{CAP}+\mathrm{CFP}\\ \left(\right[d_i/\mathrm{BI}]-1)\mathrm{BI}+\mathrm{CFP}+\mathrm{CAP}& \mathrm{if\; k}\&le;\mathrm{CAP\; and}{d}_i\&GreaterEqual;\mathrm{BI}\end{array}\right.---\left(1\right)$

Wherein: k=mod (d _i, BI)

The calculating of II, propagation delay time:

Calculate each T of transmission _i(d _i, p _i, r _i) time of needing altogether; Suppose T _i(d _i, p _i, r _i) be divided into b _iIndividual superframe transmissions, then the calculating of ED (i) need be divided into two parts: first is at preceding b _iIn-1 superframe, propagation delay time is (b _i-1) BI; Second portion is exactly T _i(d _i, p _i, r _i) at b _iTime delay in the individual superframe is only considered at b _iBe in its time before in the individual superframe;

T _i(d _i, p _i, r _i) at b _iThe calculating of the time delay in the individual superframe at first provides the definition of some parameters

(i) w: the time span of a GTS;

(ii) S _i: T _i(d _i, p _i, r _i) at preceding b _iThe GTS number that occupies in-1 superframe;

(iii) F: the timeslot number that comprises among each GTS, before realizing, just decides algorithm;

(iv)

T _i(d _i, p _i, r _i) at b _iThe GTS number that occupies in the individual superframe;

(v) E _Delay: data are propagated into the time of bunch head by node;

$E_{\mathrm{delay}}(1,\mathrm{ri})=\frac{1}{R}+\frac{r_i}{v}---\left(3\right)$

L is the length of data to be propagated, and R is a propagation rate, r _iFor node propagates into the distance of bunch head, v is the skyborne propagation rates of data.

(vi) ^*ED _i: T _i(d _i, p _i, r _i) at b _iFrame among the individual BI is handled the time delay that needs;

${}^{*}\mathrm{ED}_i{=\tilde{S}}_i\&times;w+E_{\mathrm{delay}}(f_{b_{i-1}},r_i)---\left(4\right)$

(vi) * ED: b _iCome T in the individual superframe _i(d _i, p _i, r _i) time delay that takies of before other node datas;

Total propagation delay time is:

$\mathrm{ED}\left(i\right)=(b_i-1)\mathrm{BI}+{\tilde{S}}_i\&times;w+E_{\mathrm{delay}}(f_{b_{i-1}},r_i)+*\mathrm{ED};---\left(5\right)$

The calculating of III, Si value:

S _i＝min{S _imin，7-S _imin}；

(vii) with S _iValue substitution formula (2) obtain

Just can be Ti (d _i, p _i, r _i) the concrete GTS of distribution;

IV, redistributing to GTS (UGTS) that do not have to use:

T at first has been ranked _i(d _i, p _i, r _i) order, get preceding 3 UGTS that the task arrangement is new of formation then, at first judge T _i(d _i, p _i, r _i) middle p _iSize is p with the many nodes of transmission data _iBefore big node is placed on formation; When two or more p occurring _iWhen equating, judge delay requirement d again _i, with d _iThe little front that is placed on formation; After the arrangement of finishing formation, consider that generally speaking UGTS mostly is three most among the CFP; UGTS is redistributed to two to three T before the formation _iGet final product, consider fairness simultaneously, each T _iTo redistribute a UGTS.

The present invention has following beneficial effect, considers the time bar D of different node transmission data _iWith the transmission time ED (i) that should take; In addition, after distributing GTS to give each node, redistribute the GTS (UGTS) that does not have use in the preceding scheduling process by effective method again, reach the raising bandwidth availability ratio thereby improve the GTS utilization rate.This invention has good performance in the transmission time during sensitive traffic, and can realize at user terminal easily.

Description of drawings

Fig. 1 is a whole functional Organization Chart of the present invention;

Fig. 2 is the fine setting schematic diagram of limit value among the present invention the time;

Fig. 3 is the rough schematic that UGTS forms among the present invention;

Fig. 4 is emulation simulation result of the present invention (needing the amount of packets of transmission and the function of a TMR) schematic diagram;

Fig. 5 is emulation simulation result of the present invention (needing the data total amount of transmission and the function of a bandwidth availability ratio) schematic diagram;

Embodiment

As shown in Figure 1, the Organization Chart of whole functional of the present invention mainly comprises 3 modules: from the nodal information collection module, from nodal information processing, administration module and host node scheduling enforcement module.

(1) from the nodal information collection module: the effect of this module be responsible for to collect respectively time span value from node GTS, timeslot number that each GTS comprises, each business to be transmitted the time limit value, data to be propagated length, packet propagation speed, node propagates into the distance of bunch head, information such as the skyborne propagation rate of grouped data.These information need be carried out preliminary processing from the nodal information collection module, pass to again from nodal information processing, administration module.

(2) from nodal information processing, administration module: the function of this module is that the information from the nodal information collection module is carried out concrete algorithm computation and management of information, and the detailed process of this process is with reference to concrete steps of the present invention.Pass to the host node scheduling through the data after this resume module and implement module.

(3) module is implemented in the host node scheduling: the function of this module is that host node generates concrete scheduling snoop queue according to the schedule status information that passes over from nodal information processing, administration module, thereby realizes concrete scheduling process.

The present invention will be further described below in conjunction with embodiment:

Utilize method based on time-sensitive transmission and bandwidth optimization under a kind of IEEE802.15.4 of being used for network environment: respectively selection is dispatched on the basis of delay requirement from node fully satisfied, and by redistributing to UGTS, reach the raising bandwidth availability ratio thereby improve the GTS utilization rate, concrete steps are as follows:

I, the time limit value fine setting:

Comprise 1 host node and 7 in the given piconet from node, each has 10 groups of data to be transferred T from node _i(d _i, p _i, r _i) (i ∈ (1 ..., 10)).The time limit value d of transmission wherein _iFor 1BI arrives the 10BI random value, need the total amount of data p of transmission _iSelected at random from 1KB to 50KB, from node to bunch head apart from r _iFor 10M arrives the 50M random value.The transmission of GTS carrying data is to carry out in CFP, so when limit value was in CFP when having only, it was only significant.So at first need to the time limit value finely tune, its fine setting after value defined be D _iD _iComputing formula as follows:

$D_i=\left\{\begin{array}{cc}\left(\right[d_i/\mathrm{BI}]-1)\mathrm{BI}+\mathrm{CFP}+\mathrm{CAP}& \mathrm{if\; k}\&GreaterEqual;\mathrm{CAP}+\mathrm{CFP}\\ \left(\right[d_i/\mathrm{BI}]-1)\mathrm{BI}+k& \mathrm{if\; k}>\mathrm{CAP\; and\; k}<\mathrm{CAP}+\mathrm{CFP}\\ \left(\right[d_i/\mathrm{BI}]-1)\mathrm{BI}+\mathrm{CFP}+\mathrm{CAP}& \mathrm{if\; k}\&le;\mathrm{CAP\; and}{d}_i\&GreaterEqual;\mathrm{BI}\end{array}\right.---\left(1\right)$

Wherein: k=mod (d _i, BI)

Specific as follows shown in Figure 1: A is exactly the situation of k 〉=CAP+CFP among the figure, at this moment D _i＜d _iB is exactly k＞CAP and k＜CAP+CFP situation among the figure, at this moment D _i=d _iC is exactly k≤CAP and D among the figure _i〉=BI situation, D at this moment _i＜d _i

Some other major parameter is provided with as shown in table 1:

Table 1

Parameter name	Value
		Beacon frame factor B O	8
Superframe factor S O	6
		Data rate R	250Kbps
The timeslot number F that comprises among the GTS	4
		aBaseSuperFrameDuration	15.36ms

The calculating of II, propagation delay time:

This part is calculated each T of transmission _i(d _i, p _i, r _i) time of needing altogether, also be the propagation delay time ED (i) of each node.Suppose T _i(d _i, p _i, r _i) be divided into b _iIndividual superframe transmissions, the calculating of ED (i) will be divided into two parts so: first is at preceding b _iIn-1 superframe, propagation delay time is (b _i-1) BI; Second portion is exactly T _i(d _i, p _i, r _i) at b _iTime delay in the individual superframe.This a part of time delay generally all can be less than BI, so as long as consider at b _iBe in its time before in the individual superframe.

T _i(d _i, p _i, r _i) at b _iThe calculating of the time delay in the individual superframe at first provides the definition of some parameters

(i) w: the time span of a GTS;

(ii) S _i: T _i(d _i, p _i, r _i) at preceding b _iThe GTS number that occupies in-1 superframe, the calculating of its value has detailed introduction below;

(iii) F: the timeslot number that comprises among each GTS, before realizing, just decides algorithm;

(iv)

T _i(d _i, p _i, r _i) at b _iThe GTS number that occupies in the individual superframe;

(v) E _Delay: data are propagated into the time of bunch head by node;

$E_{\mathrm{delay}}(1,\mathrm{ri})=\frac{1}{R}+\frac{r_i}{v}---\left(3\right)$

L is the length of data to be propagated, and R is a propagation rate, r _iFor node propagates into the distance of bunch head, v is the skyborne propagation rates of data.

(vi) ^*ED _i: T _i(d _i, p _i, r _i) at b _iFrame among the individual BI is handled the time delay that needs;

Can obtain by last surface analysis

(vii) * ED: b _iCome T in the individual superframe _i(d _i, p _i, r _i) time delay that takies of before other node datas;

* the calculating of ED need be added up T _i(d _i, p _i, r _i) node data of front propagates the distribution situation in superframe, and a stack Z (T is set _i) be recorded in the distribution situation of the frame of each node in a period of time, promptly before b _iThe position of-1 superframe and * ED _iSize and position.In order to simplify stack Z (T _i) complexity, only be recorded in T _i(d _i, p _i, r _i) before the substep situation of 4 transformation tasks.When calculating T _i(d _i, p _i, r _i) time, as long as call stack Z (T _i) in b _iThe data addition of frame gets final product.Through above analysis, can obtain total propagation delay time now and be:

$\mathrm{ED}\left(i\right)=(b_i-1)\mathrm{BI}+{\tilde{S}}_i\&times;w+E_{\mathrm{delay}}(f_{b_{i-1}},r_i)+*\mathrm{ED};---\left(5\right)$

The calculating of III, Si value:

Because the transformation task of all considerations of this algorithm all is based on time-sensitive, have

ED(i)≤D _i； (6)

With formula (5) substitution (6) formula, can obtain the S of a minimum _IminConsider the finite capacity (having only 7 GTS) of each superframe, S _iWith S _IminFollowing relation is arranged:

S _i＝min{S _imin，7-S _imin}； (7)

With S _iValue substitution formula (2) obtain We just can be Ti (d _i, p _i, r _i) the concrete GTS of distribution;

IV, redistributing to GTS (UGTS) that do not have to use:

The reason that UGTS occurs mainly is because S _i≤ S _IminSpecifically can see shown in Figure 2.Under the simple scenario shown in the figure, when at the 2nd BI, because T ₁Propagated and finished, do not had again under the situation of new task.T ₂And T ₃Only taken 5 GTS according to original pre-defined algorithm, two remaining GTS have been exactly UGTS.

Redistributing UGTS is another focus of the present invention.When running into more complex situations, redistribute these UGTS bandwidth utilization is improved, can also reduce T _i(d _i, p _i, r _i) propagation delay time.The present invention proposes the algorithm of a kind of UGTS of redistributing, its T that at first has been ranked _i(d _i, p _i, r _i) order, get preceding 3 UGTS that the task arrangement is new of formation then.T is ranked _i(d _i, p _i, r _i) order algorithm as follows:

At first judge T _i(d _i, p _i, r _i) middle p _iSize is p with the many nodes of transmission data _iBefore big node is placed on formation.When two or more p occurring _iWhen equating, judge delay requirement d again _i, with d _iThe little front that is placed on formation.After the arrangement of finishing formation, consider that generally speaking UGTS mostly is three most among the CFP.Therefore, UGTS is redistributed to two to three T before the formation _iGet final product, consider fairness simultaneously, each T _iTo redistribute a UGTS.

V, algorithm simulating interpretation of result

The emulation of algorithm is based on the WPAN model among the OPNET Modeler 14.5 (Educational Version) and carries out.In order to analyze its performance better, on same network, also carried out the emulation of EDF and FCFS algorithm.Each algorithm has all carried out 30 emulation, and the simulation result data among Fig. 4 and Fig. 5 are not assembly averages of the ratio of overstepping the time limit (TMR) and bandwidth availability ratio (BU) of the data transmission period that obtains of this 30 emulation.

As seen from Figure 4, the TMR of this paper algorithm is 100% basically, and the transfer of data that just means the overwhelming majority is can overstepping the time limit, and this is that ED (i)≤Di has been controlled in strictness because in the design of this paper algorithm.And EDF and FCFS algorithm are along with the increase TMR value of transmission data total amount can decline.Simulation result Fig. 5 shows that then this paper algorithm has 50% raising than EDF and FCFS on bandwidth availability ratio, reached a good effect basically.

The invention discloses a kind ofly, optimize the IEEE802.15.4 network dispatching method of bandwidth usage simultaneously based on time-sensitive transmission.At first, consider the time bar D of different node transmission data _iWith the transmission time ED (i) that should take.In addition, after distributing GTS to give each node, redistribute the GTS (UGTS) that does not have use in the preceding scheduling process by effective method again, reach the raising bandwidth availability ratio thereby improve the GTS utilization rate.This invention has good performance in the transmission time during sensitive traffic, and can realize at user terminal easily.

Claims (1)

1. one kind is used for utilizing method based on time-sensitive transmission and bandwidth optimization under the IEEE802.15.4 network environment, it is characterized in that:

I, the time limit value fine setting:

Given one group of data T that need transmit _i(d _i, p _i, r _i), d wherein _iBe the time limit value of transmission, p _iBe the total amount of data of needs transmission, r _iBe distance from node to bunch head; At first need to the time limit value finely tune, its fine setting after value defined be D _iD _iComputing formula as follows:

$D_i=\left\{\begin{array}{cc}\left(\right[d_i/\mathrm{BI}]-1)\mathrm{BI}+\mathrm{CFP}+\mathrm{CAP}& \mathrm{if\; k}\&GreaterEqual;\mathrm{CAP}+\mathrm{CFP}\\ \left(\right[d_i/\mathrm{BI}]-1)\mathrm{BI}+k& \mathrm{if\; k}>\mathrm{CAP\; and\; k}<\mathrm{CAP}+\mathrm{CFP}\\ \left(\right[d_i/\mathrm{BI}]-1)\mathrm{BI}+\mathrm{CFP}+\mathrm{CAP}& \mathrm{if\; k}\&le;\mathrm{CAP\; and}{d}_i\&GreaterEqual;\mathrm{BI}\end{array}\right.---\left(1\right)$

Wherein: k=mod (d _i, BI)

The calculating of II, propagation delay time:

Calculate each T of transmission _i(d _i, p _i, r _i) time of needing altogether; Suppose T _i(d _i, p _i, r _i) be divided into b _iIndividual superframe transmissions, then the calculating of ED (i) need be divided into two parts: first is at preceding b _iIn-1 superframe, propagation delay time is (b _i-1) BI; Second portion is exactly T _i(d _i, p _i, r _i) at b _iTime delay in the individual superframe is only considered at b _iBe in its time before in the individual superframe;

T _i(d _i, p _i, r _i) at b _iThe calculating of the time delay in the individual superframe at first provides the definition of parameter;

(i) w: the time span of a GTS;

(ii) S _i: T _i(d _i, p _i, r _i) at preceding b _iThe GTS number that occupies in-1 superframe;

(iii) F: the timeslot number that comprises among each GTS, before realizing, just decides algorithm;

(iv)

T _i(d _i, p _i, r _i) at b _iThe GTS number that occupies in the individual superframe;

(v) E _Delay: data are propagated into the time of bunch head by node;

$E_{\mathrm{delay}}(1,\mathrm{ri})=\frac{1}{R}+\frac{r_i}{v}---\left(3\right)$

L is the length of data to be propagated, and R is a propagation rate, r _iFor node propagates into the distance of bunch head, v is the skyborne propagation rates of data;

(vi) ^*ED _i: T _i(d _i, p _i, r _i) at b _iFrame among the individual BI is handled the time delay that needs;

${}^{*}\mathrm{ED}_i={\tilde{S}}_i\&times;w+E_{\mathrm{delay}}(f_{b_{i-1}},r_i)---\left(4\right)$

(vii) * ED: b _iCome T in the individual superframe _i(d _i, p _i, r _i) time delay that takies of before other node datas;

Total propagation delay time is:

$\mathrm{ED}\left(i\right)=(b_i-1)\mathrm{BI}+{\tilde{S}}_i\&times;w+E_{\mathrm{delay}}(f_{b_{i-1}},r_i)+*\mathrm{ED};---\left(5\right)$

The calculating of III, Si value:

S _i＝min{S _imin，7-S _imin}；

With S _iValue substitution formula (2) obtain

Just can be Ti (d _i, p _i, r _i) the concrete GTS of distribution;

IV, redistributing to GTS (UGTS) that do not have to use:

T at first has been ranked _i(d _i, p _i, r _i) order, get preceding 3 UGTS that the task arrangement is new of formation then, at first judge T _i(d _i, p _i, r _i) middle p _iSize is p with the many nodes of transmission data _iBefore big node is placed on formation; When two or more p occurring _iWhen equating, judge delay requirement d again _i, with d _iThe little front that is placed on formation; After the arrangement of finishing formation, consider that generally speaking UGTS mostly is three most among the CFP; UGTS is redistributed to two to three T before the formation _iGet final product, consider fairness simultaneously, each T _iTo redistribute a UGTS.

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