Capacity And Delay Performance Based On Node Characteristics In Ad Hoc Networks

An ad hoc network is a self-configuring network where nodes can be dynamically deployed and work immediately without the aid of any existing infrastructure. Because of the characteristics of high independency and strong survivability, the ad hoc network has been widely applied in many occasions with temporary communication needs, such as military field, disaster relief, etc.The capacity and delay are two important parameters to evaluate the performance of ad hoc networks. The capacity is determined as the average number of bits per sec-ond that can be transmitted by each node to its destination. Due to the impacts of the time variation of the channel strength, the limited bandwidth and the mutual interfer-ence of concurrent transmissions, the capacity of ad hoc networks is very low. Thus, how to improve capacity has become one hot research direction of ad hoc networks. The delay refers to the time needed for a packet to reach the destination node from the source node. As a result of the inherent contradictions between capacity and delay, the compromise solution of the trade-off between capacity and delay is also a technical difficulty faced by the related research works.On the basis of summarizing the existing works, this paper constructs two net-work models with node characteristics (including mobility, correlation, heterogeneity and selfishness) of application scenarios and then analyzes the capacity and delay per-formance, respectively. On the one hand, combined with node correlated mobility and heterogeneity, a heterogeneous wireless network with correlated mobility is proposed. In such a network, there are two types of nodes, called user nodes and master nodes. Specifically, each user node is the source or destination of a traffic flow and each master node serves as relay forwarding packets for user nodes so as to reduce the end-to-end delay. On the other hand, combined with node mobility and selfishness, we propose a selfish network where each node chooses to send its own packets or those of other n-odes with different probabilities. The main contributions of this paper are summarized as follows:(1) In the heterogeneous network with correlated mobility, we provide a simple, asymptotically optimal scheduling and routing scheme which maximizes the network capacity in order sense. We also derive the scaling laws of delay and explore the trade-off between capacity and delay by adjusting network settings.(2) In the selfish network, we present a selfish two-hop relay algorithm with pack-et redundancy (Selfish-2HR-/algorithm) to describe the selfish behaviors of nodes. Through modeling the packet transmission process with Markov chains, we derive the closed-form (rather than order sense) results for per-node throughput capacity, end-to-end delay and cost delivery, respectively. Moreover, we find that node selfishness has a great impact on these three parameters of network performance by analysis and prediction of simulation results and theoretical results.