Stochastic Methods for Dynamic OVSF Code Assignment in 3G Networks
Stochastic Methods for Dynamic OVSF Code Assignment in 3G Networks
复制标题
3G 网络中动态 OVSF 代码分配的随机方法
DOI：
10.1007/978-3-540-74871-7_13
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发表时间：
2007
期刊：
影响因子：
--
通讯作者：
A. Kavak
中科院分区：
文献类型：
--
作者：
Mustafa Karakoç;A. Kavak
在宽带码分多址（WCDMA）系统中，正交可变扩频因子（OVSF）码被广泛用于提供可变数据速率以支持不同的带宽需求。许多文献都深入研究了OVSF代码的最优动态代码分配方案。与以往研究采用传统（CCA）或动态（DCA）码分配方案分配OVSF码不同，本文采用遗传算法（GA）和模拟退火（SA）等随机优化方法，根据OVSF码树中现有的交通密度自适应构建种群。此外，还研究了GA（选择、交叉和突变技术）和SA（冷却计划、内环数量）参数对OVSF动态编码分配问题的影响。仿真结果表明，与CCA和DCA方案相比，GA和SA方案降低了码块概率，提高了频谱效率。
Orthogonal variable spreading factor (OVSF) codes are widely used to provide variable data rates for supporting different bandwidth requirements in wideband code division multiple access (WCDMA) systems. Many works in the literature have intensively investigated to find an optimal dynamic code assignment scheme for OVSF codes. Unlike earlier studies, which assign OVSF codes using conventional (CCA) or dynamic (DCA) code allocation schemes, in this paper, stochastic optimization methods which are genetic algorithm (GA) and simulated annealing (SA) were applied which population is adaptively constructed according to existing traffic density in the OVSF code-tree. Also, the influences of the GA (selection, crossover and mutation techniques) and the SA (cooling schedules, number of inner loop) parameters were examined on the dynamic OVSF code allocation problem. Simulation results show that the GA and SA provide reduced code blocking probability and improved spectral efficiency when compared to the CCA and DCA schemes.