This paper addresses the available capacity and robust connectivity of time division duplex based wireless mesh networks （TDD-based WMNs）. A stochastic model is presented for TDD-based WMNs. Considering the parameters that affect the network performance like ratio of control slots number to data slots number, collision probability, node density and average hopcounts, the availa- ble capacity for each node is inferred. Meanwhile, the order of transmission range for robust connec- tivity of large scale WMNs is derived. With the stochastic model and inferred available capacity per node, the performance of TDD-based WMNs using IEEE 802.16 standard is analyzed under various conditions. Simulation results indicate that the available capacity of IEEE 802.16-based TDD-based WMNs and the theoretical result have the same increasing and decreasing trend as the node density increases. Simulation results also illustrate the optimal value of the ratio of control slots number to data slots number that maximizes the available capacity.
Within a wireless opportunistic network,one of the lucky users gets an opportunity to utilize thewhole radio resource.However some of the unlucky users keep silent during an unexpected period result-ing from severe wireless environment and imperfect scheduling algorithms .An opportunistic cooperationprotocol is proposed that can achieve equivalent performance measured in terms of outage probability,inwhich scheme the opportunistic user helps to relay what need retransmitting indicated by the destinationand selects the appropriate power allocation to pursue fairness.The proposed scheme deploys superposi-tion coding and successive interference cancellation at relay and destination,respectively .To improve thespectral efficiency,the modified cooperation architecture involves two opportunistic users which work inturn.The simulation results demonstrate that the protocol obtains better performance compared with theconventional methods.
