基于隨機學習的接入網(wǎng)服務功能鏈部署算法
doi: 10.11999/JEIT180310 cstr: 32379.14.JEIT180310
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重慶郵電大學通信與信息工程學院 ??重慶 ??400065
Deployment Algorithm of Service Function Chain of Access Network Based on Stochastic Learning
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School of Communication and Information Engineering, Chongqing University of Posts and Telecommunications, Chongqing 400065, China
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摘要:
針對5G云化接入網(wǎng)場景下物理網(wǎng)絡拓撲變化引起的高時延問題,讀文提出一種基于部分觀察馬爾可夫決策過程(POMDP)部分感知拓撲的接入網(wǎng)服務功能鏈(SFC)部署方案。該方案考慮在5G接入網(wǎng)C-RAN架構(gòu)下,通過心跳包觀測機制感知底層物理網(wǎng)絡拓撲變化,由于存在觀測誤差無法獲得全部真實的拓撲情況,因此采用基于POMDP的部分感知和隨機學習而自適應動態(tài)調(diào)整接入網(wǎng)切片的SFC的部署,優(yōu)化SFC在接入網(wǎng)側(cè)的時延。為了解決維度災問題,采用基于點的混合啟發(fā)式值迭代算法求解。仿真結(jié)果表明,該模型可以優(yōu)化部署接入網(wǎng)側(cè)的SFC,并提高接入網(wǎng)吞吐量和資源利用率。
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關鍵詞:
- 網(wǎng)絡切片 /
- SFC動態(tài)部署 /
- 網(wǎng)絡拓撲感知 /
- 部分觀察馬爾可夫決策過程
Abstract:To solve problem of the high delay caused by the change of physical network topology under the 5G access network C-RAN architecture, this paper proposes a scheme about dynamic deployment of Service Function Chain (SFC) in access network based on Partial Observation Markov Decision Process (POMDP). In this scheme, the system observes changes of the underlying physical network topology through the heartbeat packet observation mechanism. Due to the observation errors, it is impossible to obtain all the real topological conditions. Therefore, by the partial awareness and stochastic learning of POMDP, the system dynamically adjust the deployment of the SFC in the slice of the access network when topology changes, so as to optimize the delay. Finally, point-based hybrid heuristic value iteration algorithm is used to find SFC deployment strategy. The simulation results show that this model can support to optimize the deployment of SFC in the access network side and improve the access network’s throughput and resource utilization.
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表 1 算法1:更新探索信念點集合
${{{B}_{\rm su}$ (1) 用式(13)計算被擴點集${B^{{\rm pr}}$ (2) for all ${} \in {B^{{\rm pr}}$ do (3) 用式(14)計算su$({})$ (4) 用式(15)計算離${B_{{\rm su}}$最遠的后繼信念點${{}''}$ (5) end for (6) 清空集合${V'}$的元素 (7) for all ${} \in {B_{{\rm su}}$ do (8) 用式(17)計算下界向量${{{α}} _{}$并加入${V'}$中 (9) end for (10) 將下界集合$\underline V $ 更新為${V'}$ (11) for all ${} \in {B_{{\rm su}}$ do (12) ${V_{{{co}}} \leftarrow \{ {}|\exists s \in S,b(s) = 1\} $ (13) ${v^0_{}\leftarrow \displaystyle\sum\limits_{{b'} \in {V_{\rm co}}} {v({{}'}) \cdot {}} $ (14) for all $ < {b_i},{v_i} > \in {B_{{\rm su}} - {V_{{\rm co}}$ do (15) $c({b_i}) \leftarrow \mathop {\min }\limits_{s \in S} \frac{{b(s)}}{{{b_i}(s)}}$ (16) $f({b_i}) \leftarrow {v_i} - \sum\limits_{{'} \in {V_{{\rm co}}}} {v({{'}){b_i}(s)} $ (17) end for (18) $v \leftarrow {v^0_} + \mathop {\displaystyle\min }_i c({b_i})f({b_i})$并將點值對$ < {},v > $加入上界集合$\mathop { V}\limits\!\!\!\!^{\displaystyle{-} } $ (19) end for 下載: 導出CSV
表 2 算法2:基于
${{{B}_{{\rm su}}$ 更新值函數(shù)向量集${{{Γ} _{{{t +}}1}$ (1) for all ${} \in {B_{{{\rm su}}$ do (2) 向量集合${{{Γ} _{t + 1,\chi }} \leftarrow \varnothing $ (3) for all $a \in A$ do (4) 向量${{{Γ} _{t + 1,\beta }} \leftarrow 0$ (5) for all $z \in Z$ do (6) 用式(18)計算${{Γ} _{t + 1}^{a,z}$ (7) ${{{Γ} _{t + 1,\beta }} \leftarrow \mathop {\arg \max }_{{α} \in {{Γ} _{t + 1}^{a,z}}} {} \cdot {{α}} + {{Γ} _1^a$ (8) end for (9) 將向量${{{Γ} _{t + 1,\beta }}$加入集合${{{Γ} _{t + 1,\chi }}$中 (10) end for (11) 將${{{Γ} _{t + 1,\chi }}$中與${}$相乘最大的向量加入${{{Γ} _{t + 1}}$ (12) end for 下載: 導出CSV
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