| Wireless ad hoc networks do not rely on fixed infrastructures,and networking of wireless ad hoc networks is fast and flexible.When some nodes break down or are destroyed and stop working,the entire network will not be affected.Therefore,the network has strong resistance to destruction and self-healing ability.In recent years,wireless self-organized networking has been widely used in many forms of networking,such as Internet of things,wireless mesh networks,car networking and UAV bee networks,which has attracted widespread attention.Distributed power control mechanism is the key to improve spatial multiplexing and reduce the average power consumption of nodes in wireless ad hoc networks.It has been a hot research topic in the field of wireless ad hoc networks.However,the distributed power control mechanism causes all nodes of the network to send signals by using heterogeneous power,which easily leads to aggravation of the overall network conflict and further serious degradation of the network saturation throughput performance.How to deal with the data collision under the condition of sending power heterogeneous? How to realize the joint design and optimization of power control and collision avoidance mechanism? How to model and analyze the network saturation throughput under power heterogeneous conditions? In view of the above problems,the existing research work cannot give the complete answer.The research work of this paper is closely around the above issues,the main innovative work done include:(1)Combined with simulation experiments,the data frame collision problem under power heterogeneous conditions is deeply analyzed.Then three two-dimensional random backoff of time /power protocolsare proposed in the framework of CSMA / CA channel access mechanism.According to the success of the current data frame transmission,the protocol adjusts the backoff window and the transmission power of the node jointly through the binary exponential backoff algorithm.The three protocols use time and power backoff alternately(PB-MAC-T),power backoff and time backoff in succession(PB-MAC-P)and time and power backoff simultaneously(PB-MAC-TP)Strategy.When a node fails to send data frames,the backoff window is enlarged to reduce the probability of nodes participating in competitive channels in the time dimension,and the transmission power is reduced to reduce the interference signal strength of the nodes in the spatial dimension.Through simulation experiments,this paper comprehensively analyzes and compares the characteristics of the above three kinds of backoff protocol.Simulation results show that the time / power two-dimensional random backoff protocol proposed in this paper can achieve better performance in terms of networkthroughput,data packet delay and average energy consumption.(2)This paper studies the method of modeling network saturation throughput under powerheterogeneous conditions.Aimed at the two-dimensional random backoff protocol of time /power(PB-MAC-T)designed in this paper,a network saturation throughput model based on three-dimensional Markov chain is proposed,which provides a theoretical basis for protocol performance analysis.The model firstly divides the signal conflicts under heterogeneous power into two categories: "persistent collision" and "instantaneous collision".Then the "pseudo-state" is used to distinguish the different two-dimensional backoff process caused by control frame collisions and data frame collisions under heterogeneous power conditions.And the capture probability of the MAC layer and the node collision probability are calculated.Finally,the expressions of the saturation throughput of the network are obtained through the non-empiric state transition probability and probability normalization condition.Through the model solution,the impacts of node transmit power on packet collision probability and network saturation throughput is further analyzed.The simulation results and numerical results show that the model is correct. |
PDF Full Text Request