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Majority of characterization studies on Vehicular Networks are based on simulations that assume little network errors and consistent signal strength. Existing VANET experiments, on the other hand, focus mostly on single-hop communication. In this paper, we present the results of an extensive measurement campaign involving up to six vehicles and evaluating the performance of IEEE 802.11 in different...
Churning of mobile users from one service provider to another is expected to become a common feature when the mobile users have freedom to choose the best wireless service. This churning behavior impacts both the technical and the economical aspects of wireless network design. In this paper, we model the churning behavior of wireless service users by using the theory of evolutionary game. We consider...
Facing the challenge of providing broadband access to high speed vehicle on motorway scenario, this paper discloses a fibre network employing star-tree architecture with a central control system in the middle to connect fixed line data collection part on one side and the wireless points to transmit information needed to on road vehicles on the other side. To implement the system, an effective coverage...
A multihop relay extension for IEEE 802.16e systems is the subject of ongoing standardization activities within the IEEE 802.16j Task Group. The emerging IEEE 802.16J standard enhances the 802.16e PHY and MAC to enable support of multihop routes between a mobile station and a base station through intermediate relay stations. Since it is believed that the capacity of a single-hop 802.16e system is...
We consider a cross-layer scheme for the downlink multiuser Orthogonal Frequency Division Multiple Access (OFDMA) for mobile WiMAX (Worldwide Interoperability for Microwave Access) based on IEEE802.16e. We propose an intelligent Medium Access Control (MAC) that adapts with physical layer in response to the different QoS requirements of the service flows in the system. Our scheme satisfies the maximum...
This paper considers decentralized cross-layer optimization for multichannel random access with partial-local knowledge. In the network scenario considered, users are not necessarily within the transmission ranges of all other users, and each user may choose to send packets to or receive packets from different users simultaneously. A criterion for cross-layer optimization is provided leading to a...
In this paper we propose the one4all cooperative access strategy to introduce a more efficient media access strategy for wireless networks. The one4all scheme is designed for the infrastructure based distributed wireless network architecture. The basic idea is that mobile devices can form a cooperative cluster using their short-range air interface and one device contends the channel for all the devices...
Cooperative communications has received increasing attention in recent years because of the ubiquity of wireless devices. Each year more mobile computing devices enter the market, most of which have limitations in terms of size, number of antennas and battery power. Cooperation enables these devices to form a virtual multiple antenna system and benefit from diversity. Most of the literature on cooperation...
Different types of power-saving techniques have been proposed in various fields to alleviate the limitation on the battery lifetime for the mobile stations (MSs). In order to provide feasible energy-conserving mechanism, three different power-saving types have been introduced in the IEEE 802.16e broadband wireless networks. By means of pre-negotiations, the MS can be absent from the serving base station...
An ever-growing demand for coverage extension, higher data-rates and improved connectivity has motivated the interconnection of mobile ad-hoc networks to fixed IP networks, to form a Hybrid Wireless Network (HWN). The convergence of ad- hoc and infrastructure network is also attractive in real-world scenarios due to its practicality and usefulness. In HWNs, gateways are generally used as an interconnection...
In its recently published TCG mobile reference architecture, the TCG Mobile Phone Work Group specifies a new concept to enable trust into future mobile devices. For this purpose, the TCG devises a trusted mobile platform as a set of trusted engines on behalf of different stakeholders supported by a physical trust-anchor. In this paper, we present our perception on this emerging specification. We propose...
This paper presents a network-assisted sink navigation mechanism in which mobile sink trajectories are computed by a sensor network for energy-efficient data collection. The key idea is that for data collection, a mobile sink (referred to as Mobile Data Harvester MDH) should visit all network nodes in order to avoid energy- intensive multi-hop routing. While incurring higher data collection delays...
A stability of routing path is of a great importance for a reliable communication in mobile ad hoc networks. We propose a novel source routing protocol that establishes a group path with virtual multiple paths to enable a robust communication. The entire mobile nodes form a disjoint set of clusters: Each has its clusterhead as a cluster leader and all the members in the same cluster are assigned an...
Physical Carrier Sensing plays a crucial role in the effectiveness of CSMA-based MAC protocols, yet its properties and impact on the system performance under slow fading channel have not been well understood. We demonstrate that carrier sensing can be highly unreliable even within the "carrier sensing range" and the channel is largely stable during a transmission between slowly moving mobile...
In this paper, we study the election of multiple leaders for intrusion detection in the presence of selfish nodes in mobile ad hoc networks (MANETs). To balance the resource consumption and prolong the lifetime of all nodes, each cluster should elect a node with the most remaining resources as its leader. However, without incentives for serving others, a node may behave selfishly by lying about its...
In this paper, a new approach is proposed to reduce handoff operation in IEEE 802.16e network. Traditional mobile approaches, such as mobile IPv6 (MIPv6) and hierarchical MIPv6 (HMIPv6), can support smoothly handoff. These approach, ,unfortunately, suffer large handoff delay and packet lost in macro mobility for mobile users. With the aid of the partner node, DAD operation can be pre-executed by the...
One of the most challenging issues in mobile ad-hoc networks (MANETs) arena, which consist of autonomous and self interested nodes, is the problem of providing incentives for nodes to cooperate in forwarding network packets. In this paper, we propose Express as a cooperation mechanism which is both efficient in computations imposed on mobile nodes and secure against deceptive threats by nodes. Using...
Significant throughput gains can be obtained in multi-user wireless system by exploiting the combination of multi-user scheduling in media access control (MAC) layer and MIMO spatial multiplexing using precoding in physical (PHY) layer. In this paper, we propose a multi-stage hybrid scheduling scheme for codebook-based precoding system, which applies different scheduling methods at different scheduling...
A computer simulation model is proposed for discrete-time doubly-selective compound-K fading channel. It first generates multiple independent mobile-to-mobile Rayleigh fading Channel Impulse Response (CIR) using the non-isotropic scattering model, then generates the cross- and auto-correlated gamma shadowing matrix using the combination of the memoryless nonlinear transformation (MNLT) method and...
This paper investigates the construction of a multicast tree satisfying Quality of Service (QoS) real-time group communication in a heterogeneous network comprising multiple Mobile Ad-hoc NETworks (MANETs) attached to the backbone Internet. The main objective of our work is to optimize the Delay- and delay Variation Bounded Multicast Tree (DVBMT) problem, which has been proved to be NP-complete. This...
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