CN105873219A - GASE based TDMA wireless Mesh network resource allocation method - Google Patents

Abstract

The invention discloses an area spectral efficiency (GASE) based TDMA wireless Mesh network resource allocation method. The problem of low network energy efficiency caused by sharp increase of wireless network energy consumption is mainly solved. According to the technical scheme, the area spectral efficiency is used as an optimization goal to establish an optimization model; the model is decomposed into a power allocation model and a time slot allocation model; a nonlinear simplex method and an interior point penalty function method are adopted to solve the power allocation model, a branch and bound method is adopted to solve the time slot allocation model on the basis of power allocation to complete time slot allocation, namely resource allocation. The GASE based TDMA wireless Mesh network resource allocation method gives consideration to the power allocation while achieving resource allocation of a TDMA wireless Mesh network, accordingly improves the energy utilization efficiency of the network, reduces the energy consumption of the network and can be used for the TDMA wireless Mesh network.

Description

TDMA wireless Mesh netword resource allocation methods based on GASE

Technical field

The invention belongs to wireless communication technology field, particularly to a kind of network resource allocation method, can be used for TDMA without Line Mesh network.

Background technology

Wireless Mesh netword is a emerging technology the most noticeable in recent years, be one can dynamic self-organization Network with self-configuring.Wireless Mesh netword based on TDMA can be to a greater extent under the network environment that height is competed Ground improves radio channel utilization, distributes channel resource efficiently, therefore can provide higher network capacity.

Having the path of a lot of redundancy between Mesh network node, the interference between link is more complicated, existing wireless The Mesh network scheduling to time slot, mainly to improve handling capacity or to reduce slot length as target, seldom considers The capacity usage ratio of whole network.

The patent of invention of Application No. 201510906203.1 discloses a kind of Wireless MESH network based on TDMA and divides The method of cloth resource distribution.Specifically, the information between neighbor node is utilized to obtain each joint in the range of double bounce alternately The time slot application situation of point, adds node load parameter in time slot application process, uses excellent in time slot allocation procedures The priority list changed gives the distribution time slot of each node, and in data transmission procedure, the path according to pieces of data stream is selected Select node sending time slots order.The method only considered time slot distribution, to reduce time delay and to improve timeslot multiplex degree, Do not account for the energy efficiency of whole network.

The patent of invention of Application No. 201410539932.3 discloses a kind of money being applicable to multi-hop wireless mesh network Source distribution method.Specifically, obtain the parameter of each node on multihop path, calculate each jumping chain in multihop path Road is for different rates and the characteristic parameter of different frame length, with the minimum optimum target of Time Slot Occupancy, end-to-end packet Error rate PER is the mathematical model that constraints sets up multiple-choice knapsack problem.The method can reduce answering of resource distribution Miscellaneous degree, but only considered time slot optimal scheme, not in view of the utilization ratio of through-put power, it is impossible to improve net The capacity usage ratio of network.

It is thus desirable to select suitably to weigh the criterion of efficiency, the target optimized as link scheduling.

Summary of the invention

Present invention aims to above-mentioned the deficiencies in the prior art, it is proposed that a kind of based on area spectrum efficiency GASE Time division multiple acess TDMA wireless Mesh netword resource allocation methods, to improve the efficiency of network, reasonable disposition Mesh The resource of network.

The technical scheme is that and be achieved in that:

One. know-why:

The definition of area spectrum efficiency GASE criterion is the ratio of whole effective ergodic capacity and area of infection.By shadow Ring area to refer in the range of certain, do not allow co-channel parallel transmission and can be affected by launching power wherein.By shadow The size ringing area depends on a lot of aspect, such as the sensitivity of through-put power, communication environments and receiver.GASE Describe the utilization ratio of through-put power when reaching the handling capacity of per unit bandwidth, so it can be as weighing channel radio The one of communication system efficiency suitably quantifies criterion.

Area spectrum efficiency GASE features the utilization ratio of through-put power when reaching the handling capacity of per unit bandwidth, GASE criterion is applied in the resource distribution of TDMA wireless Mesh netword by the present invention, by dispatching each time slot The link of transmitting data, the summation reaching all link GASE is maximum, and wherein each of the links is with the power distributed Sending data, and each link meets the rate requirement of business transmission, power is it suffices that the constraint of threshold value.

Two. implementation:

According to above-mentioned principle, present invention TDMA based on GASE wireless Mesh netword resource allocation methods, including such as Lower step:

(1) according to expression formula K of area spectrum efficiency GASE_lt, set up the optimization mould of TDMA wireless Mesh netword Type:

$\begin{array}{cc}max& \mathrm{\η}=\underset{l\∈E}{\Σ}\underset{t\∈T}{\Σ}{x}_{lt}\·K_{lt}\end{array}$

In formula, η is the area spectrum efficiency of point-to-point channel, x_lt For linkl'sTime slot distribution factor, value is 0-1 Two-valued variable；E is the set of link, and T is the set of time slot, K_lt ForThe area frequency of point-to-point channel link l Spectrum efficiency value.

Above-mentioned Optimized model constraints is: each time slot can only distribute to a link；The distribution of time slot to meet often The requirement of bar link transmission rate；Link that i-th node and jth node are constituted (i, j) on signal add with interference The threshold value that noise ratio SINR should be greater than or gives equal to system, meets with guarantee service quality over each slot and wants Ask；The max-thresholds that in each time slot each of the links, the power of distribution sends less than system；Each time slot each of the links The minimum threshold that the power of upper distribution receives not less than system；

(2) above-mentioned Optimized model is decomposed into power distribution model and time slot distribution model two parts:

(2a) set up power distribution model: max K_lt(P_lt), its link l area spectrum efficiency K_ltIt it is power P_lt's Function, this distribution model has two constraints: in each time slot each of the links, the power of distribution is not to be exceeded what system sent Max-thresholds, in each time slot each of the links, the power of distribution is no less than the minimum threshold that system receives；

(2b) use SUMT interior point method and Nonlinear Simplex Method that power distribution model is solved, obtain largest face Long-pending spectrum efficiency matrix:M=1,2 ... i, n=1,2 ... j, m ≠ n, wherein i, j are in link Node, Lnum represents the number of links in network；

(2c) result distributed based on above-mentioned power, set up time slot distribution model: η is the area spectrum efficiency of point-to-point channel；This time slot distribution model has three constraints: (I) each time slot can only distribute To a link, the distribution of (II) time slot meets the transmission rate request of each of the links, (III) x_ltBe value be 0 or 1 Two-valued variable；

(2d) use branch and bound method that time slot distribution model is solved, obtain time slot allocation matrix:Wherein t represents that timeslot number, entry of a matrix element are 0 or 1, by entry of a matrix element Substitute intoThe maximum η of η can be tried to achieve_max, i.e. complete the distribution to resource in Mesh network.

The present invention compared with prior art has the advantage that

First, in order to reduce the energy consumption of network, the resource of reasonable disposition Mesh network, the present invention proposes with area frequency This energy efficiency criterion of spectrum efficiency optimizes the resource distribution of TDMA wireless Mesh netword, this criterion as target Consider factors such as affecting the handling capacity of energy consumption, power and area coverage.

Second, Optimized model is decomposed by the present invention, uses Nonlinear Simplex Method and interior point to penalize when distributing power Function method solves, and when distributing time slot, uses branch and bound method.

Accompanying drawing explanation

Fig. 1 is the flowchart of the present invention.

Fig. 2 is the network topological diagram constituted that is connected two-by-two with 8 nodes in the present invention.

Fig. 3 is the path loss index α of the present invention impact on Nonlinear Simplex Method complexity.

Fig. 4 is that the present invention is different at timeslot number, under conditions of nodes is identical, and TDMA wireless Mesh netword area frequency spectrum Efficiency is with the variation diagram of noise.

Fig. 5 is that the present invention is identical at timeslot number, under conditions of nodes difference, and TDMA wireless Mesh netword area frequency spectrum Efficiency GASE is with the variation diagram of noise.

Detailed description of the invention

The present invention will be further described below in conjunction with the accompanying drawings:

With reference to Fig. 1, the present invention to realize step as follows:

Step 1, sets up the resource allocator model of TDMA wireless Mesh netword based on area spectrum efficiency GASE.

(1a) calculate all in network can be with the number of interconnective node pair, the most feasible link number: assume net Network has 8 nodes, i.e. node=8, draws number of links L_num=(node²-node)/2=28；

(1b) coordinate of hypothesis i-th sending node is (x_i,y_i), the coordinate of jth receiving node is (x_j,y_j), ask Outgoing link l=(i, j) distance between transmitting-receiving node:Wherein l ∈ E, i, j ∈ V；

(1c) with distance d of link_ijAs matrix element, generate Distance matrix D:

As i >=j, d_ij=0, node are nodes；

This Distance matrix D be a dimension be the matrix of 8 × 8, row and column all represents the node in network, on diagonal Element be 0, this is because in network service figure when receiving end with make a start be identical node time cannot form one Link.And link is undirected when calculating the distance between sending and receiving end, therefore element more than diagonal is also 0, Other nonzero element, such as d_ijRepresent the distance between node i and node j.Matrix D does not only give every chain The distance on road, also presents out by the relation between link and corresponding transmitting-receiving node；

(1d) matrix D of adjusting the distance is made to deform, and obtains link metricWherein M=2,3 ... node, n=1,2 ... node-1, m < n, the element in this matrix be by Distance matrix D all not Elementary composition equal to 0；

(1e) t each of the links area spectrum efficiency is sought:

Owing to network not existing the interfering link to present transmission link, only exist the interference of thermal noise, the most permissible Using point-to-point channel as current scene, using area spectrum efficiency GASE of each of the links as the mesh of Optimized model Scalar functions, when considering that power controls, the area spectrum efficiency GASE expression formula in t each of the links is:

$K=\frac{\frac{1}{ln2}E1\left(\frac{d^{\mathrm{\&alpha;}}N0}{P_l}\right)\exp \left(\frac{d^{\mathrm{\&alpha;}}N0}{P_t}\right)}{\frac{1}{\mathrm{\&alpha;}}\mathrm{\&Gamma;}\left(\frac{2}{\mathrm{\&alpha;}}\right){\left(\frac{P_{lt}}{P_{\min }}\right)}^{2/\mathrm{\&alpha;}}}$

In formula, d is the distance between sending and receiving end, and α is to rely on the path loss index of communication environments, and N0 is total Thermal noise power, P_minIt is the system minimum threshold that accepts power, P_ltIt is the power on link l,It is Exponential integral function, Γ (.) is Gamma function.As long as here the node location of link l is fixed, then distance d is one Individual definite value, the value of K is just only and P_ltRelevant.And P_ltValue unrelated with the time, after power is allocated successfully, follow-up Time slot on keep constant；

(1f) by each element d in link metric LM_ijSubstitute into the expression formula of K, obtain area spectrum efficiency matrixK_ltIdentical with link metric LM dimension, wherein k_mnIt it is the function with power as variable；

(1g) according to the K solved_ltSet up Optimized model:

Our target is that the link GASE sum making all time slots interior transmission data reaches maximum, optimizes mould accordingly Type is expressed as follows:

$\begin{array}{cc}max& \mathrm{\&eta;}=\underset{l\&Element;E}{\&Sigma;}\underset{t\&Element;T}{\&Sigma;}{x}_{lt}\&CenterDot;K_{lt}\end{array}$

In formula, η is the area spectrum efficiency of point-to-point channel, x_lt For linkl'sTime slot distribution factor, value is 0-1 Two-valued variable；E is the set of link, and T is the set of time slot, K_lt ForThe area frequency of point-to-point channel link l Spectrum efficiency value.

This Optimized model has six constraints: each time slot can only distribute to a link；The distribution of time slot to meet often The requirement of bar link transmission rate；Link that i-th node and jth node are constituted (i, j) on signal add with interference The threshold value that noise ratio SINR should be greater than or gives equal to system, meets with guarantee service quality over each slot and wants Ask；The max-thresholds that in each time slot each of the links, the power of distribution sends less than system；Each time slot each of the links The minimum threshold that the power of upper distribution receives not less than system.

For different time slot distribution factor x_ltAnd power P_lt, the value of η is different, and therefore we to search out the merit of optimum Rate distribution and time slot allocative decision, make the GASE sum within all time slots reach maximum.Due in current time slots There is a link transmission data, thus without the link having other, current ink is produced interference, only exist thermal noise and do Disturb.

Step 2, decomposes and solves above-mentioned Optimized model.

Observe this Optimized model, power and variable P_ltIt is continuous variable and time slot distribution factor x_ltIt is 0-1 variable, target letter Number is complex nonlinear function.It can be seen that this optimization problem is a nonlinear mixed-integer programming. When solving this Optimized model, not power and variable and time slot distribution factor are done combined optimization, but takes first to fix The method that a certain variable solves again.PROBLEM DECOMPOSITION is power distribution model and time slot distribution model two parts by we:

(2a) set up power distribution model:Its link l's Area spectrum efficiency K_ltIt it is power P_ltFunction, this distribution model has two constraints: in each time slot each of the links point The power joined is not to be exceeded the max-thresholds that system sends, in each time slot each of the links distribution power be no less than be The minimum threshold that system receives；

(2b) using SUMT interior point method and Nonlinear Simplex Method to solve power distribution model, concrete steps are such as Under:

(2b1) given initial pointPenalty factor μ, coefficient of reduction ν and precision ε ＞ 0, if k=1；

(2b2) structure augmented objective function F (P_lt)=η (P_lt)+μB(P_lt), whereinIts Middle g₁(P_lt)=P_max-P_lt, g₂(P_lt)=P_lt-P_min, P_minIt is the system minimum threshold that accepts power, P_maxIt it is system Launch the max-thresholds of power；

(2b3) with Nonlinear Simplex Method, withMaxF (P is solved for initial point_lt), if optimal solution isIfThen stopping iteration, output makes F (P_lt) get maximumSubstitute into K_ltExpression formula try to achieve K_max, Complete solving of power distribution model, otherwise make μ=ν * μ, k=k+1 forward (2b2) to；

It is hereby achieved that maximum area spectrum efficiency matrix: M=1,2 ... node, n=1,2 ... node, m ≠ n, the node during wherein node is link, Lnum represents in network Number of links.

(2c) result distributed based on above-mentioned power, set up time slot distribution model:η Area spectrum efficiency for point-to-point channel；This time slot distribution model has three constraints: (I) each time slot can only be distributed to Article one, link, the distribution of (II) time slot meets the transmission rate request of each of the links, (III) x_ltBe value be 0 or 1 Two-valued variable；

(2d) use branch and bound method that time slot distribution model is solved, specifically comprise the following steps that

(2d1) the constraint III of lax (2d) object function, is maximized the object function of (2d), is divided by pure algorithm Distribution transforming amount；

(2d2) value of distribution variable is judged: if the value of distribution variable is all integer, then object function maximizes, obtains Time slot allocation matrix；Otherwise, (2d3) is performed；

(2d3) selecting in distribution variable first is not the variable of integer, and its value is fixed into 0 and 1, shape respectively Become two new constraints, the two is newly retrained in the object function adding (2d) to, obtain to be solved two child resource Distribution model, solves the two child resource distribution model successively；

(2d4) different operating is carried out according to the solving result of child resource distribution model:

If solving the two child resource distribution model cannot obtain feasible distribution variate-value, then terminate this child resource is distributed The branch operation of model；

If the value solving the distribution variable that the two child resource distribution model obtains is not all integer, then return (2d3)；

If the value solving the distribution variable that the two child resource distribution model obtains is all integer, then terminate this child resource is divided Join the branch operation of model, and store its integer distribution variable and target function value, find out the target function value of maximum, it Corresponding integer distribution variable i.e. time slot allocation matrixWherein t represents timeslot number, square The element of battle array is 0 or 1, is substituted into by entry of a matrix elementThe maximum η of η can be tried to achieve_max, i.e. complete Distribution to resource in Mesh network.

The effect of the present invention can be by following emulation further instruction.

1 simulated conditions:

The emulation platform of the present invention is MATLAB, it is assumed that has 8 nodes in wireless Mesh netword and is randomly dispersed in In the square region of 1km × 1km, Fig. 1 is 8 nodes connected network topological diagram constituted, analyses of the present invention two-by-two It is based on 28 links all of in this network.

Assume signal experience path loss and the multipath fading effect of transmission, and transmission is to carry out under Rayleigh fading environment 's.The parameter used during emulation is as shown in table 1 below:

Table 1 simulation parameter

γ	2.5
		Pmax	30mW
Pmin	-100dBm
		α	4

2 emulation content and interpretations of result:

Emulation 1, according to above-mentioned simulated conditions, the network topological diagram constituted that is connected 8 nodes of the present invention two-by-two enters Row emulation, result such as Fig. 2.

Emulation 2, according to above-mentioned simulated conditions, refers to path loss Nonlinear Simplex Method complexity in the present invention The change of number α emulates, result such as Fig. 3.

As can be seen from Figure 3: when distributing power, under different path loss indexes, ask with Nonlinear Simplex Method The complexity solving unconstrained optimization problem is different, and path loss index α is the biggest, and complexity is the highest.

Emulation 3, according to above-mentioned simulated conditions, to TDMA wireless Mesh netword area spectrum efficiency GASE of the present invention Different at timeslot number, under conditions of nodes is identical, the change with noise emulates, result such as Fig. 4.

As can be seen from Figure 4: GASE declines with the increase of noise, because noise limits the size of network capacity. And when the schedulable timeslot number in network increases, GASE also can increase therewith.

Emulation 4, according to above-mentioned simulated conditions, to TDMA wireless Mesh netword area spectrum efficiency GASE of the present invention Identical at timeslot number, under conditions of nodes difference, the change with noise emulates, result such as Fig. 5.

As can be seen from Figure 5: when nodes is 8, network has 28 links, when nodes increases to 9, Link in network increases 36, and from analogous diagram 5, the increase of number of links can bring that GASE's is notable Promote, but this is with the complexity increasing network as cost.

Claims (4)

1. TDMA wireless Mesh netword resource allocation methods based on GASE, including:

(1) according to expression formula K of area spectrum efficiency GASE_lt, set up the Optimized model of TDMA wireless Mesh netword:

$\begin{array}{cc}max& \mathrm{\&eta;}=\underset{l\&Element;E}{\&Sigma;}\underset{t\&Element;T}{\&Sigma;}{x}_{lt}\&CenterDot;K_{lt}\end{array}$

In formula, η is the area spectrum efficiency of point-to-point channel, x_lt For linkl'sTime slot distribution factor, value is 0-1's Two-valued variable；E is the set of link, and T is the set of time slot, K_lt ForThe area frequency spectrum effect of point-to-point channel link l Rate value.

Above-mentioned Optimized model constraints is: each time slot can only distribute to a link；The distribution of time slot to meet often The requirement of bar link transmission rate；Link that i-th node and jth node are constituted (i, j) on signal add with interference and make an uproar The threshold value that acoustic ratio SINR should be greater than or gives equal to system, to ensure that service quality over each slot meets requirement； The max-thresholds that in each time slot each of the links, the power of distribution sends less than system；Distribute in each time slot each of the links Power not less than system receive minimum threshold；

(2) above-mentioned Optimized model is decomposed into power distribution model and time slot distribution model two parts:

(2a) set up power distribution model: max K_lt(P_lt), its link l area spectrum efficiency K_ltIt it is power P_lt's Function, this distribution model has two constraints: in each time slot each of the links, the power of distribution is not to be exceeded that system sends Big threshold value, in each time slot each of the links, the power of distribution is no less than the minimum threshold that system receives；

(2b) use SUMT interior point method and Nonlinear Simplex Method that power distribution model is solved, obtain maximum area Spectrum efficiency matrix:M=1,2 ... node, n=1,2 ... node, m ≠ n, wherein node is chain Node in road, Lnum represents the number of links in network；

(2c) result distributed based on above-mentioned power, set up time slot distribution model:η Area spectrum efficiency for point-to-point channel；This time slot distribution model has three constraints: (I) each time slot can only be distributed to Article one, link, the distribution of (II) time slot meets the transmission rate request of each of the links, (III) x_ltBe value be the two of 0 or 1 Value variable；

(2d) use branch and bound method that time slot distribution model is solved, obtain time slot allocation matrix:Wherein t represents that timeslot number, entry of a matrix element are 0 or 1, by entry of a matrix element Substitute intoThe maximum η of η can be tried to achieve_max, i.e. complete the distribution to resource in Mesh network.

The resource distribution of TDMA wireless Mesh netword based on area spectrum efficiency the most according to claim 1 Method, wherein sets up TDMA wireless Mesh netword Optimized model in step (1), carries out as follows:

(1a) number of links in network: L is calculated_num=(node²-node)/2, wherein node is nodes, L_numFor chain Way；

(1b) coordinate of hypothesis i-th sending node is (x_i,y_i), the coordinate of jth receiving node is (x_j,y_j), obtain Link l=(i, j) distance between transmitting-receiving node:Wherein l ∈ E, i, j ∈ V；

(1c) with distance d between link transmit-receive node_ijAs matrix element, generate Distance matrix D:

As i >=j, d_ij=0, node are nodes；

(1d) matrix D of adjusting the distance is made to deform, and obtains link metricWherein M=2,3 ... node, n=1,2 ... node-1, m < n；

(1e) t each of the links area spectrum efficiency is sought according to link metric:

$K=\frac{\frac{1}{\ln 2}E1\left(\frac{d^{\mathrm{\&alpha;}}N0}{P_{lt}}\right)\exp \left(\frac{d^{\mathrm{\&alpha;}}N0}{P_{lt}}\right)}{\frac{1}{\mathrm{\&alpha;}}\mathrm{\&Gamma;}\left(\frac{2}{\mathrm{\&alpha;}}\right){\left(\frac{P_{lt}}{P_{\min }}\right)}^{2/\mathrm{\&alpha;}}}$

In formula, d is the distance between transmitting-receiving node, and α is to rely on the path loss index of communication environments, and N0 is total Thermal noise power, P_minIt is the system minimum threshold that accepts power, P_ltIt is the power on link l,It is Exponential integral function, Γ (.) is Gamma function；

(1f) by each element d in link metric_ijSubstitute into K expression formula in, correspondence obtain one with LM dimension phase Same area spectrum efficiency matrixWherein m=2,3 ... node, n=1,2 ... node-1, m < n.

The resource distribution of TDMA wireless Mesh netword based on area spectrum efficiency the most according to claim 1 Method, wherein power distribution model is solved by step (2b), carries out as follows:

(2b1) given initial pointPenalty factor μ, coefficient of reduction ν and precision ε ＞ 0, if k=1；

(2b2) structure augmented objective function F (P_lt)=η (P_lt)+μB(P_lt), whereinIts Middle g₁(P_lt)=P_max-P_lt, g₂(P_lt)=P_lt-P_min, P_minIt is the system minimum threshold that accepts power, P_maxIt is that system is sent out Penetrate the max-thresholds of power；

(2b3) with Nonlinear Simplex Method, withMaxF (P is solved for initial point_lt), if optimal solution isIfThen stopping iteration, output makes F (P_lt) get maximumSubstitute into K_ltExpression formula try to achieve K_max, Complete solving of power distribution model, otherwise make μ=ν * μ, k=k+1 forward (2b2) to.

The resource distribution of TDMA wireless Mesh netword based on area spectrum efficiency the most according to claim 1 Method, wherein time slot distribution model is solved by step (2d), carries out as follows:

(2d1) the constraint III of lax (2d) object function, is maximized the object function of (2d), is divided by pure algorithm Distribution transforming amount；

(2d2) value of distribution variable is judged: if the value of distribution variable is all integer, then object function maximizes, when obtaining Gap allocation matrix；Otherwise, (2d3) is performed；

(2d3) selecting in distribution variable first be the variable of integer, its value is fixed into 0 and 1 respectively, formation Two new constraints, newly retrain the two in the object function adding (2d) to, obtain the distribution of to be solved two child resource Model, solves the two child resource distribution model successively；

(2d4) different operating is carried out according to the solving result of child resource distribution model:

If solving the two child resource distribution model cannot obtain feasible distribution variate-value, then terminate this child resource is distributed The branch operation of model；

If the value solving the distribution variable that the two child resource distribution model obtains is not all integer, then return (2d3)；

If the value solving the distribution variable that the two child resource distribution model obtains is all integer, then terminate this child resource is divided Join the branch operation of model, and store its integer distribution variable and target function value, find out the target function value of maximum, it Corresponding integer distribution variable i.e. time slot allocation matrix X.