复杂用户网络在移动通信方面的应用研究

STUDY ON MOBILE COMMUNICATIONS WITH A COMPLEX UNDERLYING USER NETWORK

在传统的移动蜂窝系统研究中,所有用户都假设具有相同的行为,即他们以相等的概率打出/接听电话,以及他们以相同的移动性在网络内移动.还有,基础用户网络假设为一个全互联的网络,这暗示着所有的用户都互相认识,且以同一概率进行相互通讯.但在现实的环境中,每个用户有各自的熟人(包括家人、亲戚、朋友和同事)通讯录,其通讯录的大小也视乎个别用户而有所不同.此外,由于用户的移动性取决于各种各样的因素(如工作性质等),不同用户的移动程度也不尽相同.为了估计移动系统更接近实际的性能,我们使用无尺度网络作为潜在的用户网络模型,即一个用户的熟人数目服从幂律分布,并且研究在3种移动性(即零移动性、相同移动性和幂律移动性)下的移动系统.最后,通过计算机仿真来估计系统的性能指标(如承载话务量和阻塞率等).结果表明,用户网络结构以及用户移动性都会对移动系统的性能产生影响.

In the traditional study of mobile cellular systems, all users are assumed to have the same behaviour： they have the same probability of making/receiving a call, and they will move around the network with identical mobility. Moreover, the underlying user network is assumed to be fully connected, implying that all users know each other and they will communicate with each other with the same probability. In a practical environment, each user has a different list of acquaintances including relatives, friends and colleagues, with whom the user is most likely to make contact, and the size of the list varies with individual users. In addition, different users will acquire different levels of mobility, depending on various factors such as job or age. To evaluate the performance of a mobile cellular system more realistically, we model the user network with a scale-free network in which the number of acquaintances of a user follows a power-law distribution. Moreover, the mobile system is studied under three user mobility distributions： zero mobility, identical mobility and power-law mobility. Finally, the system performance indicators, such as the carried traffic and the blocking probabilities, are evaluated based on computer simulations, which show that both the user network configuration and the mobility of users affect the performance of the mobile system.