Energy-Efficient Topology Control In Wireless Multi-Hop Networks

Wireless multi-hop networks,as an important part in the future large-scale wireless networks,are currently a hot research area in the field of information and communication technology.Due to the characteristics of flexibility,scalability and self-organizing capability,the wireless multi-hop networks have a wide variety of applications,such as environment monitoring,military surveillance,target tracking,search and rescue.Due to the everincreasing network applications and data services,the communication industry will have many unprecedented opportunities for developments;meantime,it will also face some huge challenges.For example,the users' experiences and the networks' further developments are heavily constrained by the limited battery energy in smart devices.Therefore,the efficient usage of the network's energy resource is of great importance in the network design.Topology control,also called topology design,is an important technique in wireless multi-hop networks,which affects the network performance directly.Topology control,that is the technique to assign per-node's transmit parameters so as to get the network topology with the best possible network performance given some optimization criteria(e.g.,energyefficiency,transmission delay minimization,network lifetime maximization),plays an important role in managing the complexity of large-scale systems through self-organizing capacities.Because of this background,we focus on the energy-efficient network protocol design in wireless multi-hop networks.Specifically,taking the various requirements in different applications,such as connectivity redundancy,network lifetime,into consideration,we explore the energy-efficient topology control for wireless multi-hop networks.The main research works and contributions are summarized as follows.Firstly,we investigate the topology control to compromise between reducing the power consumption and improving the network connectivity.The objective of our initiatory work is to design a network topology which minimizes the power consumption subject to a connectivity redundancy constraint.To the best of our knowledge,this is the first work that jointly reduces the power consumption and keeps the connectivity redundancy in wireless multi-hop networks.To this end,a new topology metric,called connectivity efficiency,is defined.It allows us to choose the network node which has a large transmit power but a small contribution to network connectivity,and then to reduce its transmit power.Based on this metric,the connectivity efficiency-based topology control(CETC)algorithm is developed to determine the transmit power for each node.The network topology derived by our CETC heuristic algorithm captures the tradeoff between power consumption and connectivity redundancy.Secondly,we focus on the distributed topological decision from each selfish node's perspective with the network-wide goal to minimize the potential transmit powers at nodes,whilst maintaining the connectivity of the network.To this end,we investigate energyefficient topology control for wireless ad-hoc networks in the presence of selfish nodes.A non-cooperative game aided topology control approach is developed for minimizing the potential transmit power,whilst maintaining the network connectivity.We conceive a practical utility function,which characterizes the real interests of nodes in pursuit of both energyefficiency and network connectivity.The existence of Nash Equilibrium(NE)is proved in our theoretic analysis.Specifically,two fully distributed topology controls – algebraic connectivity-based Max-Improvement(ACMI)algorithm and ?-Improvement(ACDI)algorithm – are proposed to find the NE topologies.Both ACMI and ACDI can easily construct the stable topologies with a low information-overhead of the order O(n),where n is the number of nodes.Simulations demonstrate that our algorithms observably eliminate the redundancy of the maximum power topology and embrace several other attractive topological features.Next,we investigate a dynamic topology control scheme to improve the network lifetime for wireless multi-hop networks in the presence of selfish nodes.Similarly,a noncooperative game aided topology control approach is developed for constructing dynamic network topologies with the following design objectives: 1)reducing and balancing the energy dissipation of nodes to extend the network lifetime;2)maintaining the network connectivity.Each node in the topology control game tries to minimize its unwillingness in constructing a connected network according to its residual energy and transmit power.We prove the existence of NE and demonstrate that the NE is Pareto optimal as well.A fully distributed algorithm – topology control with lifetime extension(TCLE)– is proposed to iterate elegant solutions,i.e.,energy-efficient and energy balanced network topologies.The network nodes update their power settings according to their own residual energy,forming a series of dynamic network topologies.The dynamic network topologies derived by our TCLE algorithm extend the network lifetime significantly as compared with the existing algorithms.