面向单向交通路网的绿波协调设计方法

为提高单向交通路网运行效率,本文提出了一种单向交通路网绿波协调控制方法。首先,分析不同类型的单行环路特征,考虑行人专用相位,建立单行环路中的路段行驶时间与交叉口信号配时参数之间的约束关系,推导环路偏移绿信比的计算公式,以所有路段平均偏移绿信比最小作为优化目标,给出最佳公共信号周期优化算法;然后,分析环路偏移绿信比与各路段偏移绿灯时间的关系,根据约束关系将各个最小环路的偏移绿信比分配到环路上的单向路段,推导绿波带宽大小计算方法;随后,以单向交通路网平均带宽占比最大为目标优化交叉口绿信比,给出交叉口相位差计算方法,实现单向交通路网信号协调控制方案的优化求解;最后,以一个3×3的单向交通路网为例进行案例分析,结果表明:利用本文方法求得的信号配时方案可以获得明显的绿波效果,能够使所有交叉口的带宽占比均在70%以上,总体绿波效果优于SYNCHRO方案。针对未饱和状态下的3种不同流量输入条件,利用VISSIM仿真实验,发现与SYNCHRO方案相比,本文提出方案的路网直行车辆平均延误时间分别降低了9.0%、16.4%、26.1%,平均停车次数分别降低了31.2%、48.8%、41.6%,路网的服务水平明显提升,有效验证了本文方法的可行性与优越性。

Improved approach to enhanced Internet connectivity for mobile ad hoc networks

An improved internetworking approach is proposed to enhance the Internet connectivity which is deteriorated due to unidirectional links and blind rebroadcasting of gateway discovery packets for mobile ad hoc networks. The hybrid gateway discovery scheme that combined the advantages of a proactive and reactive gateway discovery approach is used to achieve high connectivity while keeping overhead costs low. By exchanging ad hoc on-demand distance vector （AODV） hello packet which includes additional fields named symmetric neighbor list and asymmetric neighbor list, unidirectional links are removed from route computation and broadcast storm can also be relieved simultaneously. Performance results using ns-2 simulations, under varying numbers of unidirectional links and node speeds, show that this improved Internet connectivity approach can provide better performance than others.