An Experimental Approach to Examine a Multi-Channel Multi-Hop Wireless Backbone Network

This paper presents an experimental deployment of a multi-channel multi-hop wireless backbone network (WBN) with an OpenFlow-based traffic management method. Specifically, a set of APs, each of which uses a single but different channel, is connected by Ethernet and thus constructs a Virtual AP (VAP), thereby achieving a WBN with multi-ple channels. To exibly control traffic ows transmitted over a multi-channel multi-hop WBN, we propose a simple traffic management method based on the OpenFlow control. In the performance evaluation, we rst conduct a preliminary experiment as a lab scale　and then deploy a 6-hop WBN enabling to provide the Internet access service in a conference (from proof-of-concept to a practical environment). Since the control messages are inherently transmitted with the introduction of OpenFlow, the way of isolation be-tween control plane and data plane will become a critical issue to actually deploy the proposed system for the Internet service. We additionally employ a wireless control network for the conference experiment. The experimental results show that the proposed　WBN can increase the network capacity in accordance with the number of channels, thereby providing significant throughput performance for various applications

Efficient quality of service‐aware packet chunking scheme for machine‐to‐machine cloud services

With the recent advances in machine-to-machine(M2M) communications, huge numbers of devices have become connected and massive amounts of traffic are exchanged. M2M applications typically generate small packets, which can profoundly affect the network performance. Namely, even if the packet arrival rate at the router is lower than the link bandwidth, bits per second(BPS), it can exceed the router forwarding capacity, which indicates the maximum number of forwarded packets per second(PPS). This will cause the decrease in the network throughput. Therefore, eliminating the PPS limitation by chunking small packets will enable M2M cloud services to spread further. This paper proposes new packet-chunking schemes aimed at meeting both application requirements and improving achievable router throughput. In our schemes, multiple buffers, each of which accommodates packets classified based on their delay requirement, are installed in parallel. Herein, we report on analysis of the theoretically performance of these schemes, which enabled us to derive some important features. We also propose a scheme whereby a single chunking buffer and parallel multiple buffers were arranged in tandem. Through our simulation and numerical results, we determined that these schemes provide excellent performance in reducing the number of outgoing packets from the router while meeting various delay requirements.The 2nd IEEE International Workshop on High-Performance Interconnection Networks in the Exascale and Big-Data Era (IEEE HPCA 2016),March 12, 2016, Barcelona, Spai

Cognitive Radio-Aware Transport Protocol for Mobile Ad Hoc Networks

With the proliferation of new wireless service, scarce wireless resources is expected to become a critical issue. For this reason, cognitive radio mobile ad hoc networks (CogMANET) are being developed as a promising solution to this problem. However, in CogMANET, channel switching is inherently necessary whenever a primary user with a license appears on the channel. Allowing secondary users to choose an available channel from among a wide spectrum range thus enables reliable communication in this context, but communication characteristics such as bottleneck bandwidth and RTT will change with channel switch. In response to this change, TCP has to adaptively update its congestion window (cwnd) to make an efficient use of the available resources. For this purpose, TCP CRAHN was proposed for CogMANET. In this paper, TCP CRAHN is first evaluated in cases where bottleneck bandwidth and RTT drastically change. Based on these results, TCP CoBA is proposed to further improve the throughput of the above use cases. TCP CoBA updates the cwnd based upon the available buffer space in the relay node upon channel switch, as well as other communication characteristics. Through simulations, we show that compared with TCP CRAHN, TCP CoBA improves the throughput by up to 200 percent

Masking Lossy Networks by TCP Tunnel with Network Coding

Transmission Control Protocol (TCP) with Network Coding (TCP/NC) was designed to recover the lost packets without TCP retransmission to improve the goodput performance in lossy networks. However, TCP/NC is too costly to be implemented in some types of end devices, e.g., with less memory and power. In addition, TCP/NC across loss-free but thin networks may waste scarce link bandwidth due to the redundant combination packets sacrificed for the lossy network. In this paper, we propose the TCP/NC tunnel to convey end-to-end TCP sessions on a single TCP/NC flow traversing a lossy network between two special gateways without per-flow management. We implemented and validated our proposal in Network Simulator 3, in which each gateway runs a reinforced version of TCP/NC that we previously developed. The results show that the proposed TCP/NC tunnel can mitigate the goodput degradation of end-to-end TCP sessions traversing a lossy network without any change in TCP on each end host.The 22nd IEEE Symposium on Computers and Communications (ISCC\u2717), 03 - 06 July 2017, Heraklion, Crete, Greec

Channel Bonding-Aware Access Point Selection

2018年度 電子情報通信学会九州支部 第26回学生会講演会, 平成30年9月26日, 大分大学, 大

Elastic Channel Utilization Against External Radio Interference on SDN-Enabled Multi-Radio Wireless Backhaul Networks

This paper tries to avoid a radio interference while effectively utilizing the resource of interfered channel on SDN-based wireless backhaul networks (WBNs). The densification of small cells on wireless networks is required to handle a lot of traffic for the cloud-based ICT services but inevitably needs a WBN to provide network connectivity at every cell. Since most traffic is delayed or dropped once a WBN suffers from a radio interference coming from outside of the WBN, it is general to avoid using the interfered channel or switch a route spatially. Although such countermeasures are effective to avoid an external radio interference, it could be less effective in terms of resource utilization because the interfered channel may still remain resource. From this perspective, we propose a method that estimates the residual resource of interfered channel and uses it as much as possible while avoiding the effect arising from the radio interference. Specifically, our proposed method uses the information about incoming/outgoing traffic to estimate the residual resource and migrate a part of traffic to another channel until the amount of incoming traffic and that of outgoing packets are balanced (i.e., the channel is not a bottleneck anymore). The experimental results showed that our method is able to estimate the residual resource of interfered channel and effectively use it even under external radio interference.7th IEEE International Conference on Cloud Networking (CloudNet 2018), 22-24 October, 2018, Tokyo, Japa

Accuracy improvement of Spatio-Temporal information with GPS scintillation

2018年度 電子情報通信学会九州支部 第26回学生会講演会, 平成30年9月26日, 大分大学, 大

Effective data collection scheme for real-spatial group communication over hybrid infra-ad hoc wireless networks

This paper presents an effective data collection scheme to provide group communications among appropriate members selected by each user’s geographic situation and preference (real-spatial information). When each user directly notifies central servers of user’s information via wireless network infrastructure (Wi-infra), message delivery latency and losses drastically increase due to the network congestion. Therefore, we employ representative nodes (RNs) selected in a distributed manner. The RN first collects the real-spatial information from neighboring nodes via an ad hoc network and then notifies the server via Wi-infra. From simulation experiments, our scheme can drastically reduce both message delivery latency and losses