复杂计算机网络中的相变和整体关联行为

PHASE TRANSITION AND COLLECTIVE CORRELATION BEHAVIOR IN THE COMPLEX COMPUTER NETWORK

利用相变的概念解释复杂计算机网络中广泛存在的幂律现象 ,并未考虑到网络这一复杂系统中节点之间的相互关联作用 .通过一种计算机网络模型 ,对网络中的相变和整体关联行为进行了分析和比较 .研究表明 ,随着负载的增加 ,网络节点行为的空间和时间的长程相关性逐渐增强 ,整体关联行为逐渐显现 ;在临界状态 ,网络负载变化的功率谱呈现 1 f2 的特点 ,而节点排队长度变化的功率谱服从 1 fα 分布 ,其中α≤ 2 .网络节点行为在时间和空间上的关联进一步得到说明 .

Some researchers used the conception of phase transition to explain ubiquitous power laws in the complex Internet. However, this explanation obviously ignores the correlation between nodes' behaviors. In this paper, we compare the phase transition with the collective correlation behaviors of nodes by use of a computer network model. It is shown that when the load of network is increased, the spatial and time correlation between nodes'behaviors is also strengthened and the collective correlation phenomenon emerges gradually. At the critical state, the system load fluctuates with a 1/f 2 power spectrum, and the power spectra of buffer contents fluctuations vary as 1/f α noise where α≤2. The existence of spatial-temporal correlation among nodes'behaviors is further demonstrated.