CMT(concurrent multipath transfer) can increase throughput and transmission efficiency in multihomed networks. However, it is still an important challenge about distributing traffic adaptively into multiple access networks. Based on LV(Lotka.Volterra) model, we propose an adaptive traffic distribution scheme. In the scheme, two competition modes are concluded, multiple S.D(source.destination) streams competition for bandwidth of one path and multipath competition for traffic between each multihomed S.D host pair. Actually, each access network can establish a path for S.D pairs. So, in the first mode, each path is analogous to a predator, and overall traffic in a multihomed host is analogous to prey. Then, each path has to compete for the traffic by path information, e.g., bandwidth and congestion level. In the other one, if several S.D pairs pass through a shared path simultaneously, they will compete for bandwidth of the path. Here, each S.D pair is analogous to a predator, and the bandwidth of the common path is analogous to the prey. At last, compared with other three schemes, uniform traffic distribution, greedy path selection, random path selection in OPNET simulator, the proposed scheme can perform better onreducing file transmission time and increasing network throughput in FTP service.
This paper describes a seamless three-dimensional （3-D） localization and navigation system for smartphones. The smartphone includes an atmospheric pressure sensor to measure the user＇s altitude that is combined with the outdoor Global Positioning System （GPS） and indoor WiFi-APs localization systems in a seamless 3-D localization system. The smartphone software also provides seamless navigation services by updating map information for both indoor and outdoor locations through the mobile Internet. The indoor floor information calculated from the altitude information is used to project localization anchor nodes, e.g., WiFi-AP, on different floors onto the user＇s floor with an indoor 3-D localization algorithm using projection distances based on a Received Signal Strength （RSS） algorithm. Tests show that the 3-D method reduces systematic errors and achieves much higher accuracy than the traditional two-dimensional localization method.
A fault-tolerant 1-spanner is used to preserve all the minimum energy paths after node failures to cope with fault-tolerant topology control problems in wireless ad hoc networks. A fault-tolerant 1-spanner is a graph such that the remaining graph after node failures will not only remain connected, but also have a stretch factor of one. The fault-tolerant 1-spanner is used in a localized and distributed topology control algorithm, named the k-Fault-Tolerant 1-Spanner （k-FT1S）, where each node constructs a minimum energy path tree for every local failed node set. This paper proves that the topology constructed by k-FT1S is a k-fault-tolerant 1-spanner that can tolerate up to k node failures, such that the remaining network after node failures preserves all the minimum energy paths of the remaining network gained from the initial network by removing the same failed nodes. Simulations show that the remaining network after removal of any k nodes still has the optimal energy efficiency and is competitive in terms of average logical degree, average physical degree, and average transmission radius.
为了进一步提高无线多跳网络的吞吐量,采用物理干扰模型,考虑链路速率可以随信干噪比(signal tointerference plus noise ratio,SINR)动态可调,提出了基于位势博弈的传输调度算法。通过设计合适的位势函数,使得纳什均衡点的存在性和收敛性都得到保证。同时,每个参与者在最小化自己支付的同时,使全局函数达到最优。仿真结果表明,该算法具有较好的吞吐量性能,而且有较快的收敛速度。
