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[Keyword] delivery rate(2hit)

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  • Introduction of the Parameter “Approach Ratio” for the Improvement of Higher Delivery Rate with Suppressing Network Resource Consumption in Delay Tolerant Network

    Masato HAYASHI  Susumu MATSUI  Naoki WAKAMIYA  Masayuki MURATA  

     
    PAPER-Network

      Vol:
    E94-B No:6
      Page(s):
    1669-1679

    The delay/disruption tolerant network (DTN) has been researched actively in the last years because of its high applicability to ubiquitous network services such as sensor networks and intelligent transport system (ITS) networks. An efficient data forwarding method for those network services is one of the key components in DTN due to the limitation of wireless network resources. This paper proposes a new DTN scheme for vehicle network systems by introducing the parameter, “approach ratio”, which represents node movement history. The proposal utilizes passive copy strategy, where nodes within one hop area of packet forwarders receive, copy and store packets (namely, passive copies) for future forwarding, in order to obtain higher delivery rate and lower delivery delay whilst suppressing the network resource consumption. Depending on its approach ratio, a node with passive copy decides whether it forwards the passive copy or not by referring to the approach ratio threshold. The approach ratio allows our proposal to adjust the property of both single-copy type scheme, that can lower network resource consumption, and multi-copy type scheme, that can enhance the performance of delivery rate and delay time. In simulation evaluation, the proposal is compared with three typical existing schemes with respect to network consumption, delivery rate and delivery delay. Our proposal shows the superior performance regarding the targeted purpose. It is shown that the approach ratio plays the significant role to obtain the higher delivery rate and lower delay time, while keeping network resource consumption lower.

  • Optimal Buffer Management Scheme to Maximize the Message Delivery Rate in Delay Tolerant Networks

    Yong LI  Depeng JIN  Li SU  Lieguang ZENG  

     
    LETTER-Network

      Vol:
    E92-B No:11
      Page(s):
    3499-3503

    Delay Tolerant Networks (DTNs) are able to provide communication services in challenged networks where the end-to-end path between the source and destination does not exist. In order to increase the probability of message delivery, DTN routing mechanisms require nodes in the network to store and carry messages in their local buffer and to replicate many copies. When the limited buffer is consumed, choosing appropriate messages to discard is critical to maximizing the system performance. Current approaches for this are sub-optimal or assumed unrealistic conditions. In this paper, we propose an optimal buffer management scheme for the realistic situations where the bandwidth is limited and messages vary in size. In our scheme, we design a message discard policy that maximizes the message delivery rate. Simulation results demonstrate the efficiency of our proposal.