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In this paper, we extends bandwidth balancing technique in wired networks to operate in mobile ad hoc networks (MANETs). In bandwidth balancing in Distributed-Queue-Dual-Bus (DQDB), different nodes occupy the same channel, and information about the bandwidth is transferred between nodes in the unused bandwidth. Similarly, in wireless networks, the capacity on a channel is shared by several sources...
In this paper, ultra-wideband impulse radio(UWB-IR)system inside a vehicle is considered to construct internal vehicle wireless sensor network with better performance. In a vehicle, a direct path is likely to be blocked by the seat and passengers. The channel model characteristic in a vehicle is different from other wireless systems. When using UWB systems, other wireless systems in the same frequency...
We propose two scheduling and resource allocation schemes that deal with Quality of Service (QoS) requirements in Uplink Long Term Evolution (LTE) systems. QoS for a multiclass system has been seldom taken into account in previous resource allocation algorithms for LTE uplink. In one of the new algorithms, we investigate the possibility of assigning more than one resource block and its consequences...
Relaying mechanisms for Chain Collision Avoidance (CCA) applications in Vehicular Ad-hoc Networks (VANETs) are crucial when one hop transmissions are not enough to reach all of the vehicles in a platoon at risk of accident. Taking into account that CCA-related information must be distributed to as many vehicles as possible in the shortest affordable time, a reasonable way to determine the viability...
With the rapid advancement of positioning and tracking capabilities (mobile phones, on-board navigation systems) location based services are rapidly increasing. Privacy in location based systems is addressed in many papers. Our work is focused on the trusted third party privacy framework that utilizes the concept of k-anonymity with or without l-diversity. In previous anonymization models k may be...
Routing remains one of the key challenges in vehicular networks due to their special properties such as the high mobility and the intermittent connectivity. Almost all the efficient routing solutions proposed for VANETs are based on geographic information provided by the navigation systems widely deployed in the new generation of vehicles. Typically, in these position-based protocols, a source node...
The congestion control scheme plays a critical role in the multicast communication. Without a proper congestion control mechanism, multicast protocols would cause unfairness while sharing network bandwidth with other flows. We propose a deliberated congestion control scheme to multicast multimedia contents for smart phones retrieving effectively. Our key idea is to detect the single trip time of packet...
In sparse mobile networks, nodes are connected at discrete periods of time. This disconnection may last for long periods in suburban and rural areas. In addition, mobile nodes are energy and buffer sensitive, such as in mobile sensor networks. The limited power and storage resources, combined with the intermittent connection have created a challenging environment for inter-node networking. This type...
This paper proposes efficient analytical models to dimension the required transport bandwidths for the Long Term Evolution (LTE) access network for the elastic Internet traffic (which is carried by the TCP protocol). The dimensioning models are based on the use of Processor Sharing queuing theory to guarantee a desired end-to-end application QoS target. For validating the analytical dimensioning models,...
The performance of traditional TCP congestion control protocol degrades when congestion and contention increase in ad hoc networks that use the IEEE 802.11 DCF. Many of the problems result from medium contention at the media access control (MAC) layer. In this paper, we present a new contention-based congestion control (CBCC) method according to a novel congestion information from MAC layer. This...
Geographic forwarding has been widely studied as a routing strategy for mobile ad hoc networks, mainly due to the low complexity, scalability of the routing algorithm. However, in a network with routing holes, existing geographic routing schemes such as GPSR, GOAFR could cause the throughput capacity to drop significantly due to concentration of traffic on the face of the holes. The slope-based stateless...
In the group vertical handover (GVHO) scenario, many mobile terminals (MTs) send handover requests almost at the same time. The traditional vertical handover (VHO) schemes assume that the VHO user is coming one by one, so the current user knows the decision results of previous users, then the optimal result can be obtained. In GVHO scenario, multiple VHO decisions need to be made simultaneously, if...
We focus on the problem of efficient dissemination of available gateways information throughout a Vehicular Ad-hoc Network (VANET). Contrary to previous works, we also consider how the gateway discovery protocol affects user data flows that are routed to the infrastructure network. The cases of both delay-tolerant and delay-constrained user traffic are studied. We propose two schemes targeted at reliable,...
The development of Mobile WiMAX was considered to fulfill requirements for all major traffic types present today. This means that it will have to support voice, data and video, even simultaneously in real time applications. The hard handoff (HHO) is performed, when the connection to the serving BS is broken before creating the new connection with the target BS, but has a much poorer performance for...
We address the problem of efficiently revoking certificates of malicious and compromised nodes in vehicular networks. As in previous work, our focus is making sure that vehicles receive the new list of revoked certificates (CRL) before they can be compromised. Unlike previous solutions, our work revolves around the idea of making use of existing capabilities offered by mobile network operators to...
Safety is the only way home. Broadcasting techniques have been applied widely to improve the traffic safety, especially pileup crash avoidance by sending the emergency messages to alert drivers; however, such application often suffers from the broadcast storm, hidden node, interference, and contention problem. In the paper a novel area-based broadcast protocol was proposed. Its relaying model running...
We consider the problem of designing cooperative driver assistance and collision warning systems in vehicular networks. In this problem each car has a small size state information message that should be received by its neighborhood within a short lifetime of L timeslots. Because of the safety nature of the application, communication reliability (success probability) and delay are of critical importance...
Despite recent interests in developing vertical handoff decision algorithms, an essential component of the architecture of the next generation heterogeneous wireless networks, very few studies have so far reported any meaningful comparative performance analysis. This paper attempts to fill this gap in the literature by presenting a comprehensive study on the performance of three vertical handoff decision...
In this paper we analyze the Ricean K-factor for vehicle-to-vehicle (V2V) communications in a typical open sub-urban street crossing. The channel conditions vary from non line-of sight (NLOS) to line-of-sight (LOS). The antenna arrays used for recording the radio channels consist of 4 elements with directional radiation patterns. We measured 16 individual single-input single-output channels, with...
This paper presents a new blind symbol timing offset (STO) estimation scheme for wireless orthogonal frequency division multiplexing (OFDM) systems with constant modulus constellation. In the proposed scheme, the STO estimation is performed by minimizing the power difference between either adjacent or consecutive subcarriers, which basically depends on the assumptions made on the channel conditions...
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