Congestion control is a hot topic in named data networking (NDN). Congestion control methods for NDN are classified into two approaches: the rate-based approach and the window-based approach. In the window-based approach, the optimum window size cannot be determined due to the largely changing round-trip time. Therefore, the rate-based approach is considered to be suitable for NDN and has been studied actively. However, there is still room for improvement in the window-based approach because hop-by-hop control in this approach has not been explored. In this paper, we propose a hop-by-hop widow-based congestion control method for NDN (HWCC). The proposed method introduces a window-size control for per-hop Interest transmission using hop-by-hop acknowledgment. In addition, we extend HWCC so that it can support multipath forwarding (M-HWCC) in order to increase the network resources utilization. The simulation results show that both of HWCC and M-HWCC achieve high throughput performance, as well as the max-min fairness, while effectively avoiding congestion.

Delay and Disruption Tolerant Networks (DTN) can provide an underlying base to support mobility environments. DTN is equipped with advanced features such as custody transfer and hop by hop routing which can tackle the frequent disconnections of mobile devices by buffering bundles and dynamically making hop-by-hop routing decisions under intermittent connectivity environment. In this paper, we have proposed a DTN routing protocol HALF (Handoff-based And Limited Flooding) which can manage and improve performance of disrupted and challenging communication between mobile nodes in the presence of an infrastructure network consisting of fixed interconnected nodes (routers). HALF makes use of the general handoff mechanisms intended for the IP network, in a DTN way and also integrates a limited flooding technique to it. Simulation results show that HALF attains better performance than other existing DTN routing protocols under diverse network conditions. As the traffic intensity changes from low to high, delivery ratio of other DTN routing protocols decreased by 50% to 75% whereas in HALF such ratio is reduced by less than 5%. HALF can deliver about 3 times more messages than the other protocols when the disrupted network has to deal with larger size of messages. If we calculate the overhead ratio in terms of 'how many extra (successful) transfer' is needed for each delivery, HALF gives less than 20% overhead ratio while providing a good delivery ratio.

In this paper, an effective congestion control algorithm is proposed to increase the end-to-end delivery success ratio of upstream traffic by reduction of buffer drop probabilities and their deviation in wireless sensor networks. According to the queue length of parent and child nodes, each child node chooses one of the parents as the next hop to the sink and controls the delay before transmission begins. It balances traffics among parents and mitigates congestion based on congestion level of a node. Simulation results show that the proposed algorithm reduces buffer drop probabilities and their deviation and increases the end-to-end delivery success ratio in wireless sensor networks.

In this letter, we propose a network-adaptive video streaming scheme based on cross-layered hop-by-hop video rate control in wireless multi-hop networks. We argue that existing end-to-end network-adaptive video rate control schemes, which utilize end-to-end statistics, exhibit serious performance degradation in severely interfered wireless network condition. To cope with this problem, in the proposed scheme, intermediate wireless nodes adjust video sending rate depending upon wireless channel condition measured at MAC (Medium Access Control) layer. Extensive experimental results from an IEEE 802.11a-based testbed show that the proposed scheme improves the perceptual video quality compared to an end-to-end scheme.

Overview of Cell Switch Router (CSR) and the CSR prototype system are described. CSR can simultaneously support both connection oriented IP flows and connectionless IP flows. CSR contains cell switch fabric and IP packet switch fabric to achieve high throughput IP forwarding. IP packets are forwarded either through a cut-thru packet transmission, in which packet are forwarded without reassembling IP packet nor IP header processing, or through a conventional hop-by-hop IP packet forwarding. This paper describes and proposes the mechanism to forward the connectionless IP packet flows at the CSR. A CSR prototype system has been developed. The CSR prototype system uses PVC connections to transfer the IP packets. With the CSR prototype system, we can make sure that CSR system can achieve a high throughput, i.e., 2.4 Gbps aggregated throughput. For end-to-end TCP/IP packet transmission, more than 90 Mbps can be achieved and realtime video transmission (30 Mbps video) can be achieved.