Catálogo de publicaciones - libros

Recently, with the advent of the wireless Internet, IPv6, and P2P communications, the seamless transmission of a constant streaming data through wireless Internet has been widely accepted as a new research area. In this paper, we address a seamless transmission of constantly generated streaming data from a moving object to a remote site. We divide the whole wireless communication environments into an indoor environment, where the main communication method is the WLAN and an outdoor, where the main communication method is CDMA cellular Network and assume that the mobile server is able to move anywhere. We develop algorithms, implement them on a PDA-based hardware platform, and show some of the results. We think that, with some improvement of the performances, this work can be applied to many services such as P2P communication, file sharing services such as Napster or Soribada, and constant monitoring of the mobile objects.

When a mobile device is accessing Internet, it is important to have undisrupted communication with the wired network in the event of handover. This paper studies multi-hop handover in IPv6 based hybrid wireless networks. A generic handover scheme with notification mechanism is proposed. Simulation results under different scenarios demonstrate that this scheme can reduce the packet loss and handover delay without incurring too much signaling overhead during the multi-hop handover.

We are noticing the emergence of various internet-ready electronic devices as well as popular laptops and personal digital assistances, and most of us want to access the Internet while moving our locations. Recently, new internet protocol IPv6 is being extended to support not only host mobility but also network mobility. Real situation will be a nested mobile network, where mobile networks would be nested as they change locations. Most serious problem in a nested mobile network is the complexity of routing path of packets, and the complexity grows as the nesting level increases. In this paper, we propose ’direct tunneling method’, which delivers packets through optimized path even when mobile networks are nested. We show the effectiveness of our method by simulation results.

When using the Mobile IP, which is the representative technology to secure the mobility in general IP networks, the packet loss during the handover is inescapable. To remedy the packet loss problem, the smooth handover was introduced. However, this solution is also flawed. In particular, the smooth handover causes the packet sequence to be disrupted during the packet forwarding procedure. In turn, it may result in the degradation of the network performance. The same problem also occurs in the HPi (High-speed Portable Internet) system; the next generation portable IP service system. The HPi system, which provides the high speed data service just like xDSL and leased line in wired internet, aims to guarantee the portability, mobility, and the differentiated service based on IEEE 802.16. In this paper, we will propose a handover mechanism and a packet sequence control algorithm that prevent the packet loss and the out-of-sequence packet problem for differentiated service in the HPi system.

The IEEE 802.15.3 WPAN (Wireless Personal Area Network) has been designed to provide a very high-speed short-range transmission capability with QoS provisions. The unidirectional channel allocations for the guaranteed time slots, however, often result in poor throughput when a higher layer protocol such as TCP requires a full-duplex transmission. In this paper we propose a mechanism, called TCP transfer mode, that provides the bidirectional transmission capability between TCP sender and receiver for the channel time allocations (CTAs) of the high-rate WPAN. As our scheme does not require additional control messages nor additional CTAs, the throughput of a TCP connection on the high-rate WPAN can be greatly improved. Our simulation results show that the proposed scheme outperforms any methods of TCP transmission according to the current standard of the WPAN.

In this paper we present an adaptive determination method of the MAP domain size that can reduce the communication cost between a mobile node and correspondent nodes by assigning a different size of the MAP domain by each node in hierarchical mobile IPv6. Every node is categorized by the residence time in one subnet within the previous visited MAP domain. According to the node’s mobility pattern, a slow-moving node can have a small size of MAP domain and a fast-moving node can have a large size of MAP domain as well. Analysis experiments are presented in this paper to evaluate the performance of the proposed method and compare it with the existing scheme.