Wireless communication in a network of mobile devices is a challenging and resource-demanding task, due to the highly dynamic network topology and the wireless channel randomness. This paper investigates information broadcast schemes in 2-D mobile ad hoc networks where nodes are initially randomly distributed and then move following a random direction mobility model. Based on an in-depth analysis of the popular susceptible-infectious-recovered epidemic broadcast scheme, this paper proposes a novel energy and bandwidth-efficient broadcast scheme, named the energy-efficient broadcast scheme, which is able to adapt to fast-changing network topology and channel randomness. Analytical results are provided to characterize the performance of the proposed scheme, including the fraction of nodes that can receive the information and the delay of the information dissemination process. The accuracy of analytical results is verified using simulations driven by both the random direction mobility model and a real-world trace.

This paper investigates the information dissemination process in wireless communication networks formed by vehicles. As vehicles are moving constantly, a vehicular ad-hoc network exhibits a highly-dynamic network topology and a fast-changing radio environment. These distinguishing characteristics result in random and unreliable wireless connections between vehicles. Consequently, vehicles need to work cooperatively to disseminate a piece of information to the destination. This paper analyses cooperative information forwarding schemes where each vehicle determines whether or not to forward a received packet in a decentralized manner, without the costly or even impractical demand for the knowledge of network topology. Considering a generic wireless connection model incorporating wireless channel randomness, analytical results are derived for the probability of successful delivery and the expected number of packet forwardings. Moreover, analysis is conducted on the optimal information forwarding scheme that meets a pre-designated probability of successful delivery objective using the minimum number of packet forwardings.

This paper investigates the energy efficiency of base station sleep scheduling strategies in 1-D infrastructure-based wireless communication networks formed by vehicles traveling on a highway. In certain scenarios, vehicular speeds and locations can be measured with a high degree of accuracy, and this information can be exploited to reduce the energy consumption of base stations. This paper considers cooperative base station scheduling strategies where base stations can switch between sleep and active modes to reduce the average energy consumption, while guaranteeing the connectivity of every vehicle. Analytical results on the expected amount of energy saving for a base stations are derived, which reveals for the first time the existence of a threshold parameter, determined by both the vehicular density and mobility, below which base stations can switch off and save energy, but above which no energy saving can be achieved.

This paper studies the information propagation process in wireless communication networks formed by vehicles traveling on a highway. Corresponding to different lanes of the highway and different types of vehicles, we consider that vehicles in the network can be categorized into a number of traffic streams, where the vehicles in the same traffic stream have the same speed distribution while the speed distributions of vehicles in different traffic streams are different. We analyze the information propagation process of the aforementioned vehicular network and obtain an analytical formula for the information propagation speed (IPS). Using the formula, one can straightforwardly study the impact of parameters such as radio range, vehicular traffic density, vehicular speed distribution, and the time variation of vehicular speed on the IPS. The accuracy of the analytical results is validated using simulations.

Wireless communication is notoriously lossy due to channel fading, interference and multi-path effects. This work investigates the reliability of all-to-all broadcast in lossy wireless networks where the reliability is measured by the probability that every node in the network receives or decodes the native packet of every other node. To improve the reliability, a novel network coding scheme, namely random neighbour network coding (RNNC) scheme is proposed, which is capable of adaptively generating encoding packets according to the packets received from lossy wireless channels. The network reliability is analysed theoretically and the optimal RNNC scheme that maximises the reliability of a given network is obtained. The theoretical analysis is validated using simulations and it is shown that RNNC can improve the network reliability significantly.

Broadcast in mobile ad-hoc networks is a challenging and resource demanding task, due to the effects of dynamic network topology and channel randomness. In this paper, we consider 2D wireless ad-hoc networks where nodes are randomly distributed and move following a random direction mobility model. A piece of information is broadcast from an arbitrary node. Based on an in-depth analysis into the popular Susceptible-Infectious-Recovered (SIR) epidemic routing algorithm for mobile ad-hoc networks, an energy and spectrum efficient broadcast scheme is proposed, which is able to adapt to fast-changing network topology and channel randomness. Analytical results are provided to characterize the performance of the proposed scheme, including the fraction of nodes that can receive the information and the delay of information propagation. The accuracy of analytical results is verified using simulations.

This paper studies the information propagation process in a 1D mobile ad-hoc network formed by vehicles traveling on a highway. We consider that vehicles can be divided into traffic streams; vehicles in the same traffic stream have the same speed distribution, while the speed distributions of vehicles in different traffic streams are different. Analytical formulas are derived for the fundamental properties of the information propagation process as well as the information propagation speed. Using the formulas, one can straightforwardly study the impact on the information propagation speed of various parameters such as radio range, vehicular traffic density, vehicular speed distribution and the time variation of vehicular speed.

In this paper, we consider 2D wireless multi-hop networks with mobile nodes randomly distributed on a torus, and a small number of base stations (infrastructure nodes) deterministically placed in the same area. Mobile nodes move following a random walk mobility model. A piece of information is broadcast from the base stations at the same time in a multi-hop manner using a Susceptible-Infectious-Recovered (SIR) epidemic routing algorithm. A distinguishing feature of the SIR algorithm, which leverages the mobility of mobile users, is that a relay node carries a piece of information for a predetermined amount of time and forwards it at any available opportunity during that time. We provide analytical results for the percolation probability and for the expected fraction of nodes that receive the information when the information dissemination process stops. Further, we study the time delay of the information dissemination process. The accuracy of the analytical results is verified using simulations.

Consider a wireless multihop network where nodes are randomly distributed in a given area following a homogeneous Poisson process. The hop count statistics, viz. the probabilities related to the number of hops between two nodes, are important for performance analysis of the multihop networks. In this paper, we provide analytical results on the probability that two nodes separated by a known euclidean distance are k hops apart in networks subject to both shadowing and small-scale fading. Some interesting results are derived which have generic significance. For example, it is shown that the locations of nodes three or more hops away provide little information in determining the relationship of a node with other nodes in the network. This observation is useful for the design of distributed routing, localization, and network security algorithms. As an illustration of the application of our results, we derive the effective energy consumption per successfully transmitted packet in end-to-end packet transmissions. We show that there exists an optimum transmission range which minimizes the effective energy consumption. The results provide useful guidelines on the design of a randomly deployed network in a more realistic radio environment.

In this paper, we study information propagation in a 2D mobile ad-hoc network, where mobile nodes are randomly and independently distributed on a torus following a homogeneous Poisson process with a given density. Nodes in the network move following a random direction mobility model. A piece of information is broadcast from a source node to all other nodes in the network, using a Susceptible-Infectious-Recovered (SIR) epidemic routing protocol. A distinguishing feature of the SIR algorithm, which leverages the mobility of mobile users, is that a relay node carries and forwards a piece of information for a specified amount of time. We first propose a metric fundamentally characterizing the information propagation in mobile ad-hoc networks. Then analytical results are derived for the probability that a non-zero fraction of nodes receive the information in the limit of large network size and for the expected fraction of nodes that receive the information. The analytical results are verified using simulations. The research provides useful insights on the design of mobile ad-hoc networks.

We consider wireless multi-hop networks with a finite number of (ordinary) nodes randomly deployed in a given 2D area. A finite number of gateways (infrastructure nodes) are deterministically placed in the same area. We study the connectivity between the ordinary nodes and the gateways. In real applications, it is often desirable to limit the maximum number of hops between the ordinary nodes and the gateways in order to provide reliable services. On the other hand, requiring every ordinary node to be connected to at least one gateway imposes strong requirement on transmission range/power or the number of gateways. Therefore it is beneficial to allow a small fraction of ordinary nodes to be disconnected from the gateways so that the network is only partially connected. Based on the above two considerations, we provide analytical results on the k hop partial connectivity, which is the fraction of ordinary nodes that are connected to at least one gateway in at most k hops. The research provides useful guidelines on the design of wireless multi-hop networks.

In this paper, we study the information propagation speed in a 1D mobile ad hoc network formed by vehicles Poissonly distributed on a highway and travelling in the same direction but with random Gaussianly-distributed speeds, independent between vehicles. Assume that time is divided into time slots of equal length and that each vehicle changes its speed at the beginning of each time slot, independent of its speed in other time slots. We derive analytical formulas for the IPS in the above network under the unit disk model. Using the formula, we can straightforwardly study the impact on the information propagation speed of various parameters such as vehicle density, speed and radio range. The accuracy of the formula is validated using simulations. The research provides useful guidelines on the design of vehicular ad hoc networks.

We analytically characterize the energy consumption per successfully transmitted packet in end-to-end packet transmissions in a wireless sensor network where nodes are identically and independently distributed in a square area following a homogeneous Poisson process. It is assumed that a greedy forwarding protocol is used for routing. We obtain analytical results on the average number of hops between any two nodes if the transmission is successful and the average number of hops traversed by packets before being dropped if the transmission is unsuccessful. A transmission is unsuccessful if the packet sent from a source to a destination has to be dropped at an intermediate node because the greedy forwarding routing protocol is unable to find a next-hop node that is closer to the destination. Based on the above analysis, we derive the effective energy consumption per successfully transmitted packet. We show that there exists an optimum transmission range which minimizes the effective energy consumption and such optimum transmission range can be computed based on our analysis.