MinHop (MH) Transmission strategy to optimized performance of epidemic routing protocol

Delay tolerant network aims to provide the network architecture in environments where end-to-end path may never exist for long duration of time Furthermore dynamic topology changes limited buffer space and non stable connectivity make routing a challenging issue The research contribution regarding DTN routing protocols can be categorized in to single and multi copy strategies A single copy strategy makes less use of network resources but suffers from long delay and less delivery probability Multi copy schemes enjoy better delivery probability and minimum delivery delay at the cost of heavy use of network resource Moreover DTN nodes operate under short contact duration and limited transmission bandwidth Therefore it is not possible for a node to transmit all messages from its forwarding queue Hence the order at which the messages are forwarded becomes very vital In this paper we propose a forwarding queue mode named MinHop We prove through simulations that the proposed policy performs better then FIFO in terms of delivery probability overhead message drop and rela

Threshold Based Best Custodian Routing Protocol for Delay Tolerant Network

Delay Tolerant Network (DTN) is a kind of network in which the source may not be able to establish the stable and uninterrupted path to destination due to network partitioning, dynamic topology change and frequent disconnections. In order to dealt disruption and disconnections a store, carry and forward paradigm is used in which node stores the incoming messages in its buffer, carries it while moving and forward when comes within the transmission range of other nodes. Message forwarding contributes and important role in increasing its delivery. For instance, probabilistic routing protocol forwards message to a node having high probability value to meet message destination. These protocols cannot handle a situation in which the node continually transmits messages even the probability difference is very small. In this paper, we have proposed a routing protocol known as Threshold Based best custodian Routing Protocol (TBbcRP) for delay tolerant network. We have proposed a threshold-based method to compute the quality value which is the ability of node to carry message. A self-learning mechanism has been used to remove the delivered messages from the network. Moreover, a buffer aware mechanism has been used that make sure availability of buffer space at receiver before message transmission. We have compared the performance of TBbcRP with Epidemic, PRoPHET and Delegated Forwarding. The proposed TBbcRP outperforms in terms of maximizing the delivery probability, reducing number of transmissions and message drop

Adaptive message size routing strategy for delay tolerant network

Delay tolerant network (DTN) is a kind of computer network that suffer from the frequent disconnections, network partitioned and unstable network connectivity, therefore maintaining an uninterrupted route from source to destination is not possible. Therefore, the transmission of message is achieved via intermediate nodes by adopting a novel transmission mechanism called store-carry and forward where node stores the incoming message in its buffer, carries it while moving and forward it when it comes in the transmission range of other nodes. DTN routing protocols can be either single copy or multi copy. In single copy protocols, the node forwards the unique copy of message along a single path. These protocols suffer the long delivery delay. In multi copy protocols, the node diffuses multiple copies of same message along dissimilar paths. Thus, message can reach destination via more than one path. However, the replication process consumes high volume of network resources such as buffer space, bandwidth and node energy. The probabilistic routing strategies for instance PRoPHET Protocol minimizes the consumption of resources and forwards a message to a custodian by using a metric of delivery probability. The probability describes the suitability of a node to meet the destination of message. However, when node mobility pattern is not symmetric the probabilistic computations cannot predict the accurate forwarding decision. In this paper, we have proposed a novel message forwarding strategy called Adaptive Message-Size Routing strategy (AMRS) by which a node handovers the copy of message to its neighboring nodes by using a metric named as mean threshold (MTH). We have compared the performance of AMRS with Epidemic and PRoPHET routing protocols. The proposed routing strategy has performed better in terms of maximizing delivery probability while minimizes message drops and number of transmissions

Reactive weight based buffer management policy for DTN routing protocols

Delay-tolerant networks (DTNs) are distinguished by low connectivity and/or unreliable links, dynamic topology change and network partitioning. Therefore, each node transmits the multiple copies of the message to increase its delivery likelihood. This phenomenon produces congestion that results in the dropping of earlier stored messages. The objective of buffer management policy is to determine which message should be eliminated when the buffer overflow happens. The existing buffer management policies can be divided into two categories: (i) local knowledge-based and (ii) global knowledge based. In a DTN environment, getting global knowledge is impossible and local knowledge-based policies are more practical. This study focuses on the local knowledge-based policies in order to reduce the drop ratio and maximize the delivery. In this paper, we presented a buffer scheduling policy called as weight based drop policy. In this proposed scheme, we dynamically adjust message weight criteria assuming message’s properties, which are message size, remaining time-to-live, message stay time in queue, hop count, and replication count. In order to utilize the buffer efficiently we use weight criteria for finding the most appropriate message for drop and rank the forward messages to its neighboring nodes. The simulation performed in ONE simulator. The simulation results of weight based drop policy by using map based mobility movement outperformed the existing DLA, FIFO, MOFO, SHIL and LIFO in terms of reducing a number of transmission, dropped messages, overhead and enhanced delivery and buffer time average

Priority Queue Based Reactive Buffer Management Policy for Delay Tolerant Network under City Based Environments.

Delay Tolerant Network (DTN) multi-copy routing protocols are privileged to create and transmit multiple copies of each message that causes congestion and some messages are dropped. This process is known as reactive drop because messages were dropped re-actively to overcome buffer overflows. The existing reactive buffer management policies apply a single metric to drop source, relay and destine messages. Hereby, selection to drop a message is dubious because each message as source, relay or destine may have consumed dissimilar magnitude of network resources. Similarly, DTN has included time to live (ttl) parameter which defines lifetime of message. Hence, when ttl expires then message is automatically destroyed from relay nodes. However, time-to-live (ttl) is not applicable on messages reached at their destinations. Moreover, nodes keep replicating messages till ttl expires even-though large number of messages has already been dispersed. In this paper, we have proposed Priority Queue Based Reactive Buffer Management Policy (PQB-R) for DTN under City Based Environments. The PQB-R classifies buffered messages into source, relay and destine queues. Moreover, separate drop metric has been applied on individual queue. The experiment results prove that proposed PQB-R has reduced number of messages transmissions, message drop and increases delivery ratio

Mean drop an effectual buffer management policy for delay tolerant network

Traditional routing protocols e.g. TCP/IP, AODV cannot be configured in environments where end-to-end path is not stable due to network partitioned, dynamic topology changes and node mobility. Delay tolerant Network (DTN) has emerged as a technology by which the communication architecture is formed through intermittently connected mobile nodes. These networks are categorized as opportunistic since further availability of connections cannot be predicted. Thus, the routing protocols transmit the multiple copies of each message around the connected nodes. Each node then carries this message copy in its buffer until the transmission opportunity arises. This hop-by-hop mobility of message(s) makes the quick progress towards destination. However, such redundant diffusion of messages produces high congestion in the network and a situation occurs where new message arrives at a node and its buffer is full. In this case, the node must drop the buffered message(s) to sustain this new arrival. The function of buffer management policy is to minimize this drop. In this paper we propose a buffer management policy called as MeanDrop. This policy computes the mean of buffered messages at the congested node and drops only those message(s) which have the size greater than or equal to this mean value. The simulation results have shown that the proposed policy MeanDrop (MD) out performs well as compared to existing Evict Shortest Time First (ESTF) and Evict Most Forwarded Fist (MOFO) in terms of message relay, message drop, delivery probability and overhead