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This paper addresses the problem of compensating for motion-induced Doppler frequency offset in multicarrier acoustic communication systems based on orthogonal frequency division multiplexing (OFDM). In mobile acoustic systems, Doppler effect can be sever enough that the received OFDM signal experiences non-negligible frequency offsets even after initial resampling. To target these offsets, a practical...
We propose a progressive pseudo-analog video transmission scheme that simultaneously handles SNR and bandwidth variations with graceful quality degradation for mobile video streaming. With the inherited SNR-adaptability from pseudo-analog transmission, the proposed progressive solution acquires bandwidth adaptability through an innovative scheduling algorithm with optimal power allocation. The basic...
As demands on limited spectrum continue to increase, much focus is being placed on increasing spectral efficiency. One approach which has a great deal of potential in some propagation environments is to use multiple element antennas (MEAs) at the transmitter and/or receiver. Such systems have become commonly referred to as multiple-input multiple-output (MIMO).
Long Term Evolution Advanced (LTE-A) is the fourth generation (4G) wireless cellular communication standard. A covert channel is a noticeable threat to network security because it is able to transfer data under the overt channel. In this paper, a new class of covert channel coined as SNsteg is proposed, designed for LTE-A system. The SNsteg peculiarly utilizes the feature of Sequence Number (SN) fields...
We experimentally demonstrates a VLC downlink based on two LEDs and one mobile user. A self-adaptive STBC is proposed in this work to suppress the interference between VLC nodes, resulting in a significant mobile feasibility.
We shed new light on the mechanism behind how the dynamic behavior of a packet scheduler at the link layer in mobile networks degrades the accuracy of conventional available bandwidth (i.e., unused capacity of an end-to-end path) estimation methods that use a probing packet train (i.e., a set of multiple probing packets). Most of the conventional methods, which were originally designed for wired networks,...
Emerging wireless network and mobile computing enable user-generated mobile video streaming to be shared and consumed in a novel manner. The feature of shared wireless medium, multihop data forwarding, and time-varying channel quality seriously limits the quality of experience (QoE), partially owing to the lack of mechanisms for effectively utilizing multi-rate channel resources. However, the existing...
The rapid growth of available services depending on location awareness has led to a more and more increasing demand for positioning in challenging environments. Global navigation satellite system (GNSS) based positioning methods may fail or show weak performance in indoor and urban scenarios due to blocking of the signals and multipath propagation. In contrast, cellular radio signals provide better...
Congestion management detects congestion in a network and resolves it, e.g., by dropping or marking packets. A challenge is to drop or mark the right packets if fair capacity sharing is desired, especially if a few heavy users monopolize the bandwidth, e.g., by opening many flows or using non-responsive transport protocols. To this end, we propose activity-based congestion management (ABC). Users...
The design of a dual-channel broadband millimeter-wave receiver front-end for the next generation mobile communication is presented in this article. The front-end operates at 28GHz with 2GHz and 500MHz bandwidth in radio frequency (RF) and immediate frequency (IF) respectively. A scheme of single downconversion is used and a compact substrate integrated waveguide (SIW) bandpass filter is designed...
Mobility considerations in multicast algorithm design usually focus issues of mobile receivers while few researches emphasize on mobile multicast sources issues. However, mobility of source is a critical issue causing global tree disruption. Furthermore, major research challenges in the delivery of group applications over Wireless Mesh Networks (WMN) comprise delivery of large volume data, incurring...
A future smart phone will become a mobile terminal that communicates with a number of diverse sensors perpetually. This never-resting RF communication will cut the battery life drastically, unless the power consumption per RF communication reduces accordingly while maintaining reasonable performance. This paper presents the recent evolution of a translational circuit (or N-path filter) to enable a...
Even with modern physical-layer technologies in LTE networks, the capacity of cellular networks is still far from sufficient to satisfy the insatiable bandwidth demand of mobile applications. Owing to common interests among mobile users, Device-to-Device (D2D) communication has emerged as a viable alternative to offload cellular traffic, with the promise of substantially alleviating the need for cellular...
This paper presents an evaluation of the adjacent channel operation between Aeronautical Mobile System (AMT) and International Mobile Telecommunication (IMT) systems operating at 1300–1518 MHz frequency band. Three proposed IMT band allocations are considered. Analytical results of interference calculations are compared with simulation results obtained with the SEAMCAT software. Coordination distances...
Recent advances in high-speed mobile networks have revealed new bottlenecks in ubiquitous TCP protocol deployed in the Internet. In addition to differentiating non-congestive loss from congestive loss, our experiments revealed two significant performance bottlenecks during loss recovery phase: flow control bottleneck and application stall, resulting in degradation in QoS performance. To tackle these...
The average smart phone user picks up the device 1,500 times a week. Wireless communication appears to be taking over our lives but it also presents interesting challenges to RF designers. This paper contends that the mobile terminal will emerge as a central command post for most of our daily affairs and will therefore sustain an increasingly heavier load in terms of speed, power dissipation, and...
Nowadays the spectrum regulations landscape is changing towards more flexible spectrum management schemes, such trends are expected to make additional spectrum resources available and lowers the spectrum access hurdles. In this paper, different spectrum aggregation scenarios have been compared focusing on the tradeoff between the total cost of ownership and the targeted QoS under different market...
MobiCoStream, an acronym for Mobile Collaborative upStream, refers to Real-time video upstream of captured video in Mobile Augmented Reality (MAR) applications. MAR for tele-assistance deals with providing real-time assistance to the user through the power of Augmented Reality. Real-time applications have strict delay requirements which need to be met in order to satisfy the user Quality of Service...
In order to solve the rbuf blocking in concurrent multipath transfer, firstly, this paper analyzes the reason for receiving buffer blocking and the disadvantages of traditional retransmission policies. And then, it proposes an improved retransmission policy — RTX-CR (retransmission-congestion window and RTT), which can reduce rbuf blocking. The simulation indicates that the retransmission policy can...
In mission-critical visual communications, and situations where the need for network capacity a concern, focus is on the impact images may have for operations, not the technical quality of the image. By focusing communications capacity on operationally relevant content, savings in network loads over 99% are realistic while keeping full image quality for relevant parts. Based on several space projects,...
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