1,904 research outputs found
Seamless Infrastructure independent Multi Homed NEMO Handoff Using Effective and Timely IEEE 802.21 MIH triggers
Handoff performance of NEMO BS protocol with existent improvement proposals
is still not sufficient for real time and QoS-sensitive applications and
further optimizations are needed. When dealing with single homed NEMO, handoff
latency and packet loss become irreducible all optimizations included, so that
it is impossible to meet requirements of the above applications. Then, How to
combine the different Fast handoff approaches remains an open research issue
and needs more investigation. In this paper, we propose a new Infrastructure
independent handoff approach combining multihoming and intelligent
Make-Before-Break Handoff. Based on required Handoff time estimation, L2 and L3
handoffs are initiated using effective and timely MIH triggers, reducing so the
anticipation time and increasing the probability of prediction. We extend MIH
services to provide tunnel establishment and switching before link break. Thus,
the handoff is performed in background with no latency and no packet loss while
pingpong scenario is almost avoided. In addition, our proposal saves cost and
power consumption by optimizing the time of simultaneous use of multiple
interfaces. We provide also NS2 simulation experiments identifying suitable
parameter values used for estimation and validating the proposed mode
Mobile Networking
We point out the different performance problems that need to be addressed when considering mobility in IP networks. We also define the reference architecture and present a framework to classify the different solutions for mobility management in IP networks. The performance of the major candidate micro-mobility solutions is evaluated for both real-time (UDP) and data (TCP) traffic through simulation and by means of an analytical model. Using these models we compare the performance of different mobility management schemes for different data and real-time services and the network resources that are needed for it. We point out the problems of TCP in wireless environments and review some proposed enhancements to TCP that aim at improving TCP performance. We make a detailed study of how some of micro-mobility protocols namely Cellular IP, Hawaii and Hierarchical Mobile IP affect the behavior of TCP and their interaction with the MAC layer. We investigate the impact of handoffs on TCP by means of simulation traces that show the evolution of segments and acknowledgments during handoffs.Publicad
Integrated Support for Handoff Management and Context-Awareness in Heterogeneous Wireless Networks
The overwhelming success of mobile devices and wireless
communications is stressing the need for the development of
mobility-aware services. Device mobility requires services
adapting their behavior to sudden context changes and being
aware of handoffs, which introduce unpredictable delays and
intermittent discontinuities. Heterogeneity of wireless
technologies (Wi-Fi, Bluetooth, 3G) complicates the situation,
since a different treatment of context-awareness and handoffs is
required for each solution. This paper presents a middleware
architecture designed to ease mobility-aware service
development. The architecture hides technology-specific
mechanisms and offers a set of facilities for context awareness
and handoff management. The architecture prototype works with
Bluetooth and Wi-Fi, which today represent two of the most
widespread wireless technologies. In addition, the paper discusses
motivations and design details in the challenging context of
mobile multimedia streaming applications
A packet error recovery scheme for vertical handovers mobility management protocols
Mobile devices are connecting to the Internet through an increasingly heterogeneous network environment. This connectivity via multiple types of wireless networks allows the mobile devices to take advantage of the high speed and the low cost of wireless local area networks and the large coverage of wireless wide area networks. In this context, we propose a new handoff framework for switching seamlessly between the different network technologies by taking advantage of the temporary availability of both the old and the new network technology through the use of an "on the fly" erasure coding method. The goal is to demonstrate that our framework, based on a real implementation of such coding scheme, 1) allows the application to achieve higher goodput rate compared to existing bicasting proposals and other erasure coding schemes;
2) is easy to configure and as a result 3) is a perfect candidate to ensure the reliability of vertical handovers mobility management protocols. In this paper, we present the implementation of such framework and show that our proposal allows to maintain the TCP goodput(with a negligible transmission overhead) while providing in a timely manner a full reliability in challenged conditions
Flat Cellular (UMTS) Networks
Traditionally, cellular systems have been built in a hierarchical manner: many specialized cellular access network elements that collectively form a hierarchical cellular system. When 2G and later 3G systems were designed there was a good reason to make system hierarchical: from a cost-perspective it was better to concentrate traffic and to share the cost of processing equipment over a large set of users while keeping the base stations relatively cheap. However, we believe the economic reasons for designing cellular systems in a hierarchical manner have disappeared: in fact, hierarchical architectures hinder future efficient deployments. In this paper, we argue for completely flat cellular wireless systems, which need just one type of specialized network element to provide radio access network (RAN) functionality, supplemented by standard IP-based network elements to form a cellular network. While the reason for building a cellular system in a hierarchical fashion has disappeared, there are other good reasons to make the system architecture flat: (1) as wireless transmission techniques evolve into hybrid ARQ systems, there is less need for a hierarchical cellular system to support spatial diversity; (2) we foresee that future cellular networks are part of the Internet, while hierarchical systems typically use interfaces between network elements that are specific to cellular standards or proprietary. At best such systems use IP as a transport medium, not as a core component; (3) a flat cellular system can be self scaling while a hierarchical system has inherent scaling issues; (4) moving all access technologies to the edge of the network enables ease of converging access technologies into a common packet core; and (5) using an IP common core makes the cellular network part of the Internet
Motorized cart
Motorized cart is known as an effective tool and timeless that help people carry heavy loads. For farmers, it has an especially vital tool for moving goods. Oil palm farmers typically uses the wheelbarrow to move the oil palm fruit (Figure 10.1). However, there is a lack of equipment that should be further enhanced in capabilities. Motorized carts that seek to add automation to wheelbarrow as it is to help people save manpower while using it. At present, oil palm plantation industry is among the largest in Malaysia. However, in an effort to increase the prestige of the industry to a higher level there are challenges to be faced. Shortage of workers willing to work the farm for harvesting oil palm has given pain to manage oil palm plantations. Many have complained about the difficulty of hiring foreign workers and a high cost. Although there are tools that can be used to collect or transfer the proceeds of oil palm fruits such as carts available. However, these tools still have the disadvantage that requires high manpower to operate. Moreover, it is not suitable for all land surfaces and limited cargo space. Workload and manpower dependence has an impact on farmers' income
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