pi
DELAY Tolerant pi Networks, including space communication and networking in rural regions, vehicular ad hoc networks, and underwater networks, have attracted heavy research interest over the last few years. Unlike the conventional networks, the recently appearing DTNs are defined by the absence of the guarantee of connectivity, the normally low encounter frequency of DTN nodes, and large propagation delays in the network.
For instance, the in-transit messages of DTNs, referred to as bundles, might be forwarded only when two DTN nodes N are in each other’s transmission range and meet one another during an interval. In case no other DTN node is in the transmission range of the DTN node. It will buffer the existing pi bundles and transport them until another DTN node comes into its transmission range. Thus, the DTN’s bundle propagation process is of a store-carry-and-forward type, and the bundles are opportunistically forwarded toward destinations using intermittent links.
The DTN’s opportunistic pi data propagation has been extensively studied up to now, and various effective opportunistic routing algorithms have been proposed on the assumption that every node in a DTN is willing to forward other people’s bundles. But when rational agents, for example, organizations or humans, control DTN nodes, the DTN nodes will be selfish and may refuse to assist other nodes to deliver bundles, so the hypothesis is broken.
For instance, to save power, buffer, and computing capacity, a selfish DTN node will not like to cooperate if it is not advantageous to it directly, which may render a well-designed opportunistic routing useless. Thus, how to effectively and efficiently solve the selfishness problem in DTNs has become an extremely difficult task to improve the packet delivery performance of DTNs.
Network Model
Delay Tolerant pi Networks are generally defined by the unguaranteed connectivity and low encounter frequency between any pair of nodes in the network. In our model, we treat a DTN as a directed graph. In the DTN, a source, S, can send packets to a destination, D, through the mobility of DTN nodes with an appropriate data forwarding algorithm. At present, based on whether they support multiple copies of a message relaying in the network or not, the current data forwarding algorithms can be classified into single-copy and multi-copy algorithms.
In the single-copy algorithm, a single copy is forwarded in the networks until it reaches the destination. In the multi-copy algorithms, including flooding or spray routing, multiple copies are forwarded in the networks. Because of the high number of message copies in the networks, this type of approach takes a lot of resources, which are limited in DTNs.
In this paper, to explain the practical incentive clearly, latest news about pi network, latest news on pi, latest pi network news, pi latest news today, latest pi updates, pi network latest we simply analyze a single-copy data forwarding protocol, i.e., for any bundle B, only one copy is first disseminated by source S, then the sole copy is opportunistically forwarded from one forwarding node to another until it arrives at destination D.
Node Model
The selfish actions of DTN pi nodes in DTNs are inevitably triggered by human entities who operate them. In our simulation, to examine the selfish DTN nodes in a nonabstract way, we consider vehicular ad hoc network as a real delay tolerant network — vehicular DTN, in which every DTN node is realized by vehicle driven by humans running in a city area with some speed. In the remainder of this paper, we will be using node and vehicle synonymously to denote the same DTN entity.
In vehicular DTNs, every vehicle is facilitated with an On Board Unit communication device, which enables various vehicles to exchange communications by the 802.11p protocol. Observe that the 802.11p physical layer supports varying bitrates between 3 and 27 Mbps, out of which the OBU devices may select.
Hence, if two cars are in each other’s transmission range, latest news pi network, latest pi network news, latest pi updates, latest news pi coin, pi coin latest news say 300 meters, they may share bundles. Typically, a car is nearly resource-unbounded, whereas the embedded OBU communication device is regarded as being resource-constrained, i.e., buffer and computational power-constrained. Hence, there could be numerous selfish DTN nodes in the networks. To save buffer space, selfish DTN nodes can be highly unwilling to help others unless it is beneficial to them. The Pi protocol introduced here has a fair reward. During the charging and rewarding phase, when a bundle is forwarded to the destination node.
Those intermediate nodes are for forwarding. But if the bundle does not arrive at the destination node, Will not pay any credits. So, it is just to the source node. For the intermediate nodes, even though they cannot receive credits for their forwarding in this situation, they can still boost their good reputation values from the TA. When these intermediate nodes still perceive being fair for bundle forwarding. Furthermore, as provably secure short signature schemes are used, the authentications of the signatures can serve as powerful witnesses.
When an intermediate node fails to take part in forwarding, it cannot receive any reward. Thus, based on the above analysis, the proposed latest Pi protocol can achieve a fair incentive in the DTN network. The free riding attack is a well-known selfish attack in DTN, carried out by two selfish DTN nodes that seek to exchange messages without spending their credits. If the two DTN selfish nodes are connected by a single link, this attack does not make sense because they can exchange messages directly without the assistance of other nodes. When there exists at least one normal node between them, the above attack is feasible.
PERFORMANCE EVALUATION
In this section, we study the performance of the proposed Pi protocol using a custom simulator built in Java. The metrics of performance utilized in the assessment are the delivery ratio, or the ratio of messages generated to correctly delivered to the destination over a specified interval the average delay, or the average time between when a message is generated at some source and when it is delivered successfully to its destination. Both the delivery rate and mean delay can be employed to analyze how well the introduced Pi protocol with some incentive policy can deliver the bundle to the destination within some time.
Alternatively, when stimulated with some incentive in the network, the delivery rate will rise. Since each selfish node has different selfish factors, latest news pi coin the same incentive can’t meet all stimulation conditions of selfish nodes in the Equation. So, there remains a small proportion of selfish nodes. Intuitively, the smaller the fraction of selfish nodes, the higher the incentive.
From the figure, this observation is supported, in which the delivery rate with high incentive is significantly greater than that with low incentive and comes close to that with no selfish nodes, in the DTN network. Thus, we can be certain that, while selecting an adequate incentive, the suggested Pi protocol can efficiently promote the selfish nodes and enhance the performance of the DTN pi protocol network under a high delivery ratio.
CONCLUSIONS
In this work, we proposed a realistic incentive Pi protocol for encouraging selfish nodes to cooperate and forward bundle packets in DTNs. By implementing the correct incentive policy, the proposed Pi protocol can not only enhance the entire DTN network’s performance in terms of high delivery ratio and low average delay but also ensure fairness among DTN nodes. Comprehensive security analyses have demonstrated that the proposed Pi protocol can withstand most attacks initiated by selfish DTN nodes. Besides, there have been comprehensive simulations to illustrate the efficiency of the proposed Pi protocol.
In our future research, we will design a fair incentive protocol for multi-copy algorithms. Moreover, we will combine Pi with anonymity to give each DTN node privacy protection. In DTNs, the absence of contemporaneous routing and excessive heterogeneity of network conditions make the selfishness issue significantly different from that of classical wireless ad hoc networks, and most incentive solutions in current use can not be used in DTNs.
Recently, two works on incentive-aware routing in DTNs have been presented, which are directly related to the designed Pi protocol. In Sheaved et al.’s initial work, the effect of selfish behavior in DTNs was examined. They present, based on the results of the simulation, that having selfish DTN nodes can severely affect the total delivered traffic.
To counter the harm inflicted by selfish DTN nodes, they employ the pair-wise tit-for-tat as a simple, strong, and realistic incentive mechanism for DTNs and construct an incentive-aware routing protocol where selfish DTN nodes can optimize their utilities under TFT constraints. Extensive simulation results are pro vided to demonstrate that the latest TFT mechanism can improve aggregate delivered traffic in the entire DTN network.