Yoshikuni Onozato

A comparison of different paging mechanisms for mobile IP

This paper proposes two Individual paging schemes, then presents a comparative analysis on the signaling cost functions of Mobile IP (MIP) with different paging protocols and paging schemes and investigates constructing optimal paging areas using discrete system model as a mobility model. In wireless mobile Internet, mobile hosts often visit foreign networks that might be far away from their home networks and the occurrences of their inter-domain movement are relatively rare. In this scenario, our analytical results show that paging, particularly individual paging, can significantly improve the total signaling cost of MIP. We show that Domain paging can bring about considerable cost saving compared to FA (Foreign Agent) paging. Our results also demonstrate the significant advantages of Individual Paging over Static Aggregate Paging. The results show that specifying the optimal paging area size is critical in saving signaling cost of MIP with paging support.

MPEG-4 optimal transmission over SCTP Multi-streaming in 802.11 wireless access media

Stream control transmission protocol (SCTP) is a transport layer protocol for the next-generation Internet. In this paper, we investigate optimally condition for MPEG 4 video communication with SCTP in 802.11 wireless access media. We focus on the multi-streaming feature and the partial reliability extension in SCTP and compare performance of MPEG4 video quality under the policy w th/without differentiated retransmission among streams. Differentiated policy allows packets belonging to a specific stream to be retransmitted, while packets are transmitted exactly one time (no retransmissions) in homogeneous policy. By computer simulation, we show that SCTP can (1) improve the video quality by exploiting the multi-streaming and partial reliability features, and (2) enhance the video transmission quality can by adjusting SCTP fast retransmit threshold.

On the Capacity and Outage Probability of an Air-Ground CDMA Cellular System with Imperfect Power Control

Accurate power control is an essential requirement in the design of cellular code division multiple access (CDMA) systems. The performance analysis for the three-dimensional air-to-ground (AG) cellular system becomes an important issue. In this paper, assuming that the imperfect power control follows log-normal statistics, the capacity and outage probability of the aeronautical communication system are examined and quantified. The system capacity is calculated with a given outage probability and power control error. From the numerical results, it is shown that the system is rather sensitive to small power control errors.

Feasibility Study of Security Virtual Appliances for Personal Computing

Computers connected to the Internet are a target for a myriad of complicated attacks. Companies can use sophisticated security systems to protect their computers; however, average users usually rely on built-in or personal firewalls to protect their computers while avoiding the more complicated and expensive alternatives. In this paper we study the feasibility —from the network performance point of view— of a VM configured as an integrated security appliance for personal computers. After discussing the main causes of network performance degradation, we use netperf on the host computer to find the network performance overhead when using a virtual appliance. We are mainly concerned with the bandwidth and the latency that would limit a network link. We compared the bandwidth and latency of this integrated security virtual appliance with current market products and in both cases, the performance of the virtual appliance was excellent compared with hardware counterparts. This security virtual appliance for example allows more than an 80 Mbps data transfer rate for individual users, while security appliances generally allow only 150 Mbps for small office users. In brief, our tests show that the network performance of a security virtual appliance is on par with the current security appliances available in the market; therefore, this solution is quite feasible.

Power Saving in Wireless LANs by Adapting the Listen Interval

We are increasingly relying on wireless networks to access different Internet and Intranet services. With the current battery technologies, the manufacturers of portable wireless devices have to compromise between portability and battery life. The IEEE 802.11 standard includes a power saving mode (PSM), which is fixed and does not adapt to the varying traffic patterns. In this paper, we propose an enhancement to the standard PSM through the implementation of an adaptive listen interval that changes in accordance with traffic patterns. Our simulation tests show that the proposed technique provided better power saving compared to the standard PSM.

Optimal aggregation factor and clustering under delay constraints in aggregate sequential group paging schemes

This paper considers several optimization problems of sequential paging with aggregation mechanism which has been shown to reduce significantly the paging cost of a wireless communication system. An important problem is to find the optimal aggregation factor subject to a constraint on the average paging delay. Another problem is, given a cost function that depends on both paging cost and paging delay, how to find the optimal aggregation factor to minimize that cost function. We have formulated and shown that these can be solved nicely due to the monotonicity and convexity of the average paging cost function and paging delay function. We demonstrate that the optimization problems of the aggregate factor and subnet clustering are not separable. This leads to joint optimization problems of aggregation factor and clustering that are investigated in this paper. The paper presents different algorithms to solve these joint optimization problems using the monotonicity in the aggregation factor and the number of clusters of the average paging cost and delay with the unconstrained optimal clustering and the structures of the constrained optimal clustering.

Extended diffused key-information based routing protocol in ad hoc networks

In this paper we investigate the search path when building a wireless mesh network under extended ad-hoc network, and we propose a search method that can reduce power consumption. The route search part and the node part - which can be a mobile PC or a mobile phone, etc. -are combined in the proposed method. Moreover, we aim at improving the efficiency of the communication between nodes under the extended wireless mesh network. This is achieved by making the nodes aware of the location of each other. The proposed method provides several advantages: First of all, useless route searches are reduced by flooding using the location information between nodes. Second, we are able to construct shortest routing paths, avoid the communication with AP to pass the location information of each node, and reduce the power consumption of the nodes.

Using virtualization to simulate biological cells

In this paper, we discuss the virtualization technologies and the characteristics of biological cells. We notice that both virtual machines and cells are usually self contained, and logically independent and relatively mobile. We work to show the analogy between the two. With this level of common characteristics we conclude that it would be very beneficial for us to use virtual machines to simulate biological cells in general and suggest using teams of virtual machines to simulate biological organ functionality. In our opinion, this makes it easier to put our knowledge of biological systems into use.