在所研究的区块链网络中,优化的变量为:挖矿决策(即 m)和资源分配(即 p 和 f),目标函数是使所有矿工的总利润最大化。问题可以表述为:
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\begin{aligned} \max _{\mathbf{m}, \mathbf{p}, \mathbf{f}} & F^{\text {miner }}=\sum_{i \in \mathcal{N}^{\prime}} F_{i}^{\text {miner }} \\ \text { s.t. } & C 1: m_{i} \in\{0,1\}, \forall i \in \mathcal{N} \\ & C 2: p^{\min } \leq p_{i} \leq p^{\max }, \forall i \in \mathcal{N}^{\prime} \\ & C 3: f^{\min } \leq f_{i} \leq f^{\max }, \forall i \in \mathcal{N}^{\prime} \\ & C 4: \sum_{i \in \mathcal{N}^{\prime}} f_{i} \leq f^{\text {total }} \\ & C 5: F^{M S P} \geq 0 \\ & C 6: T_{i}^{t}+T_{i}^{m}+T_{i}^{o} \leq T_{i}^{\max }, \forall i \in \mathcal{N}^{\prime} \end{aligned}
m,p,fmax??s.t.??Fminer?=i∈N′∑?Fiminer??C1:mi?∈{0,1},?i∈NC2:pmin≤pi?≤pmax,?i∈N′C3:fmin≤fi?≤fmax,?i∈N′C4:i∈N′∑?fi?≤ftotal?C5:FMSP≥0C6:Tit?+Tim?+Tio?≤Timax?,?i∈N′?
其中:
C1表示每个矿工可以决定是否参与挖矿;
C2 指定分配给每个参与矿机的最小和最大传输功率;
C3 表示分配给每个参与矿工的最小和最大计算资源;
C4表示分配给参与矿机的总计算资源不能超过MEC服务器的总容量;
C5保证MSP的利润不小于0;
C6 规定卸载、挖掘和传播步骤的总时间不能超过最长时间约束。
在所研究的区块链网络中,我们假设 IoTD 是同质的,并且每个 IoTD 都具有相同的传输功率范围和相同的计算资源范围。
上式中:
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F_i^{miner}=(w+\alpha D_i)P_i^m(1-P_i^o)-c_1E_i^t-c_2f_i,\forall i\in\mathcal{N'}\\R_{i}=B \log _{2}\left(1+\frac{p_{i} H_{i}}{\sigma^{2}+\sum_{j \in \mathcal{N}^{\prime} \backslash i} m_{j} p_{j} H_{j}}\right), \forall i \in \mathcal{N}^{\prime}\\T_{i}^{t}=\frac{D_{i}}{R_{i}},\forall i\in\mathcal{N}^{\prime}\\T_{i}^{m}=\frac{D_{i}X_{i}}{f_{i}},\forall i\in\mathcal{N}'\\E_i^m=k_1f_i^3T_i^m,\forall i\in\mathcal{N}'\\P_i^m=\frac{k_2}{T_i^m},\forall i\in\mathcal{N}^{\prime}\\F^{MSP}=\sum_{i\in\mathcal{N}^{\prime}}\left(c_2f_i-c_3E_i^m\right)-c_3E_0\\\begin{aligned} P_{i}^{o}& =1-e^{-\lambda(T_{i}^{o}+T_{i}^{s})} \\ &=1-e^{-\lambda(zD_{i}+T_{i}^{t})},\forall i\in\mathcal{N}^{\prime} \end{aligned}
Fiminer?=(w+αDi?)Pim?(1?Pio?)?c1?Eit??c2?fi?,?i∈N′Ri?=Blog2?(1+σ2+∑j∈N′\i?mj?pj?Hj?pi?Hi??),?i∈N′Tit?=Ri?Di??,?i∈N′Tim?=fi?Di?Xi??,?i∈N′Eim?=k1?fi3?Tim?,?i∈N′Pim?=Tim?k2??,?i∈N′FMSP=i∈N′∑?(c2?fi??c3?Eim?)?c3?E0?Pio??=1?e?λ(Tio?+Tis?)=1?e?λ(zDi?+Tit?),?i∈N′?
close all
clear
clc
dbstop if all error
NP = 100;%矿工数量
para = parametersetting(NP);
para.MaxFEs =5000;%最大迭代次数
Result=Compute(NP,para);
figure(1)
plot(Result.FitCurve,'r-','linewidth',2)
xlabel('FEs')
ylabel('Token')
figure(2)
plot(Result.ConCurve,'g-','linewidth',2)
xlabel('FEs')
ylabel('Con')
当矿工数量为100时:所有矿工的利润随迭代次数的变化如下图所示
算法得到的资源分配:
1.96811552438660 0.953006101348509
1.96466685390698 0.271902260303373
1.98787052377883 0.474153524868700
1.96819942207163 0.346379035947841
1.99091543574949 0.200876712644815
1.75343624634699 0.334356132462864
1.98500749778468 0.307444848291752
1.84892091516342 0.298750104087243
1.97627537784477 0.136707719799701
1.98247708944478 0.825715938835666
1.82415247169822 0.592341764056851
1.95255969969755 0.266870044692269
1.55784064472313 0.198677986588129
1.99905703081220 0.864360471110543
1.99966672978573 0.208510255774389
1.99688659497769 0.0918824246788308
1.98550616407992 0.338463477789463
1.93993936287256 0.125644327388094
1.99699497232442 0.647475988987162
1.96398401982365 0.465688977142535
1.99091543574949 0.743184799966985
1.96990281764298 0.714108040841893
1.97038900311126 0.589313007134188
1.99476384052921 0.165976864334375
1.88837922907041 0.407249404947350
1.90123564522443 0.0259150669487571
1.96990281764298 0.865499536534992
1.98251610689349 0.423166248324710
1.79062121977309 0.134536527173266
1.86555117077209 0.433716644319901
1.99699497232442 0.527866317534775
1.99476384052921 0.688760982663683
1.97674256927618 0.287210638597892
1.76141326412447 0.433716644319901
1.98550616407992 0.494479004505169
1.93568365938428 0.210270205638780
1.76141326412447 0.134536527173266
1.99318790325672 0.463178386123276
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1.98247708944478 0.461790633870382
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1.64596073389228 0.239159634095697
1.99826774684560 0.402723342616452
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1.90398161302827 0.839744341831028
1.89043943861968 0.289783983459719
1.99699497232442 0.533319780807194
1.95116437441300 0.700957227852864
1.99121369063535 0.754607214742589
1.87983995904930 0.609769452627303
1.84892091516342 0.539298593105581
1.99977128699058 0.788773855758191
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1.88837922907041 0.0950878414681128
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1.84149233878646 0.0312600209994546
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1.99476384052921 0.121831563328420
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1.99826774684560 0.697077892570419
1.94737447735811 0.223823307777294
1.96466685390698 0.530942973106581
1.98251610689349 0.709782769737031
1.80244505169201 0.903799290199773
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1.99476384052921 0.669326947551257
1.99476384052921 0.209953433257302
1.99476384052921 0.473000128326441
1.96819942207163 0.884127095870242
1.99699497232442 0.974541259533987
1.99584133362082 0.525442981913958
1.96575023838394 0.0623933694916289
1.93792710962256 0.855551087118804
1.99740286694205 0.735027403529296
1.98550616407992 0.314664453608669
1.99620036364745 0.506153103638960
1.96811552438660 0.0309570286681788
1.97798566131583 0.189970375715465
1.98526170939456 0.118404965890552
1.99740286694205 0.879091954485326
1.99476384052921 0.983286613303637
1.65047014229422 0.0102537270833978