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The popularity of web based social networks is rapidly increasing nowadays. These solutions allow managing relationships online. There are also several mobile solutions to these networks but they are mainly limited to reaching the services of the social network from the mobile device. The fact, that the phonebook of the mobile phones also represents social relationships, can be used for detecting...
Based on the analysis of the existing utility-based forwarding mechanisms, for the inefficient forwarding of history encounter time based forwarding mechanism in the initial phase of the node movement, a Random and Encounter Time Based algorithm named RET is proposed in this paper. RET divides the nodes moving into two phases-random forwarding phase (initial phase) and utility-based forwarding phase...
It is heterogeneous wireless Networks (HWN) aggregation foundation for vertical handoff (VHO), and that is key characters of core technology for multi-network aggregation. The currently mechanism handoff trigger is analyzed, a best network selected (BNS) framework is designed, the parameters of network terminal and user terminal of effecting VHO algorithm, and which also include norm of capable parameters,...
This paper presents a new data transmission protocol in Delay Tolerant Mobile Wireless Sensor Networks, which divides the data transmission process into two phases: data reception phase and data forwarding phase, mainly fulfilling through analyzing the state of mobile nodes and using Hand up mechanism. Simulation result shows that, through the implementation of two phases, we can obtain a higher message...
The base station in IEEE 802.16, or WiMAX, networks allocates contention-based time slots for the mobile stations to transmit their requests for additional bandwidth. Using a technique called subchannelization, multiple concurrent transmissions by mobile stations can be admitted by the base station during the same contention period. For transmission during this period, each station employs a contention-resolution...
This paper proposes a slot-based persistent allocation scheme which allows WiMAX base stations (BSs) allocating resources to VoIP-like traffic in an efficient way. The proposed scheme firstly scans resource slots within the stream of data frames to identify an available resource slot for a persistent resource allocation. To facilitate the scanning process, the base station maintains a tree structure...
TCP's downlink performance during FMIPv6-enabled IEEE802.11g handoff is examined. The use of a user-initiated Handoff Notification, sent prior to handoff, is proposed. Therefore, the correspondent node is aware of the handoff-induced disruption, hence avoiding dropping the congestion window size and triggering Fast Retransmission mechanisms. During handoff, it continues to send data packets which...
In this paper, the results of outdoor-to-indoor multiple-input multiple-output (MIMO) channel measurements at 780 MHz are presented. The motivation for these measurements was to provide actual measurement data needed to extend the International Mobile Telecommunications -Advanced (IMT-A) channel models to the frequencies around 400 - 900 MHz. There are publications reporting measurement results for...
This paper proposes an analytic model to study queuing effect on the handoff performance of Mobile IPv6 (MIPv6), which has not been particularly investigated in previous literature. The presented model regards handoff process as tandem service system, and adopts a simple two-moment approximation throughout the theoretic modeling. Without other specific assumptions, the model presents a generic approach...
Performance bounds provide a solid theoretical ground for comparing different localization methods. Similarly to the actual performance, they depend on two factors, namely the accuracy of the available data that are used for localization and the geometry of the network. While the impact of the accuracy of the available data has been studied extensively, the literature on the impact of network geometry...
For existing localization algorithms, Non-Line-of-Sight (NLOS) propagation introduces some problems for the determination of the mobile position. This is because most of these algorithms depend on the information extracted from the Line-of-Sight (LOS) path such as Time-of-Arrival (ToA) or Time-Difference-of-Arrival (TDoA) received by either one or more Base Stations. On the contrary, algorithms based...
Recent research studies on green cellular networking indicate that most of the traffic is serviced by a few cell sites while the rest of the cells remain under-utilized, contributing to significant energy consumption levels. Previous proposals suggest turning off Base Stations (BSs) during low utilization periods to save energy by allowing neighboring cells to increase their coverage to provide the...
Mobile sink brings new challenges to densely deployed and large wireless sensor networks (WSNs). When the sink moves, frequent location updates from the sink can generate excessive power consumption of sensors. In this paper, we propose IAR, an Intelligent Agent-based Routing protocol that provides efficient data delivery to mobile sink. Proposed algorithm reduces signal overhead and improve degraded...
As network infrastructure and home agent under tactical wireless environment are all movable and destructible, its mobile communication can't be solved by existing Mobile IP. So this paper proposed a new hierarchical distributed mobile interconnect protocol (HDMIP) in order to solve this problem. Firstly, the paper analyzed the particularity of mobile communication under tactical wireless environment,...
Most traditional MAC protocols proposed for wireless networks assume static Network Units (shorted as NUs), which usually lead to performance degradation in mobile scenarios. In this paper, a novel hybrid MAC protocol, called MA-MAC, was presented for multi-hop mobile Tactical Data Link networks based upon the mobile characteristics of NUs. The basic point of MA-MAC is that the transmit mode of each...
While centralised approach has been considered to provide superior performance workflow coordination than market-based approach, most of the extant comparisons have been performed on the assumption that the working environments are static. This paper aims to compare the performance of the two approaches in task allocations of mobile business processes which are characterized with high level of exceptions...
SIP (Session Initiation Protocol) is standardized by Internet Engineering Task Force (IETF) as a signaling and control functionality for multimedia services (video and audio). However, SIP is a text-based protocol with messages usually exceeding several hundred bytes in size, thus causing high call set-up latency over low bit-rate links. As a consequence, SIP suffers from undesirable delay which is...
After analyzing the merits and shortcomings of some current authentication protocols for roaming in wireless mesh networks (WMNs), we propose a new protocol for roaming based on multi-signature and three-party key agreement in this paper and prove the security of the protocol through formal analysis based on the strand space model. We also show the reliability and performance gain of the protocol...
In digital mobile communication systems, speech coding is very important to increase the bandwidth efficiency. Usually, speech coding algorithms determine speech parameters, which are highly sensitive to transmission errors. In this paper, we use the residual redundancy remaining after using the Enhanced Variable Rate Codec (EVRC) algorithm for error concealment. Average residual redundancies of the...
Quality-based routing protocols are proposed to restrict message flooding within only high quality nodes in delay tolerant networks (DTNs). However, different quality threshold mechanisms have diverse impact on the network and we investigate this issue in the paper. Through theoretical analysis we show that heterogeneous threshold mechanism suffers a severe nodal cost imbalance problem. Furthermore,...
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