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Resource reservation is one of the effective solutions in guaranteeing the quality-of-service (QoS) in communication networks. In this paper, we propose a novel resource reservation scheme for dynamically managing the bandwidth resources in IEEE 802.11e-based wireless local area networks (WLANs). The proposed solution consists of two components namely (i) dynamic medium access control (MAC) scheduler...
In this paper, we present a channel state information (CSI) feedback reduction algorithm to be used in an adaptive orthogonal frequency division multiplexing (OFDM) system. Adaptive OFDM transceivers, which offer improved data rates and power efficiency over conventional OFDM systems, require a duplex connection between the transmitter and receiver such that the CSI necessary for the transmitter to...
As an advanced train control system, communication-based train control (CBTC) system can improve the utilization of railway network infrastructure and enhance the level of safety and service offered to customers. In this paper, we propose a seamless handoff scheme for CBTC systems based on Stream Control Transmission Protocol (SCTP) and IEEE 802.11p. The focus of our work is in the handoff decision...
Internet services will be pervasive in future intelligent transportation systems. To this end, vehicular Wi-Fi networks are introduced and widely deployed nowadays. However, quantitative performance in vehicular Wi-Fi networks has not been reported in the literature. In this paper, we conduct a measurement study in vehicular Wi-Fi networks to investigate the uplink and downlink throughput under diverse...
This paper proposes a communication system using Wi-Fi (IEEE802.11g) to link between the Internet and high speed rail systems traveling at around 300km/h. In order to adapt Wi-Fi for high speed mobile communication, we optimized its coverage on a rail track with a developed directional antenna, which has a communication range of around 500m by 10mW. With the antenna, however, a mobile entity had to...
Future wireless communication systems will be comprised by the integration of different radio access technologies (RATs), referred to as heterogeneous wireless network (HWN). In this paper, a realistic HWN simulator is proposed to evaluate different network selection algorithms, the main mechanism of joint radio resource management (JRRM). The simulator is designed for an HWN that comprises cellular...
Location tracking for vehicle plays a key role in increasing road safety and transportation efficiency. In this paper, a Wi-Fi based real-time tracking system which can work in both indoor and outdoor environments is presented. The proposed system estimates the location of vehicle using the Received Signal Strength (RSS) fingerprints of transmitted Wi-Fi Access Points (APs) and Particle Filter (PF)...
Train-ground communication technology is one of the key technologies for communication-based train control (CBTC), which is an automated train control system for railways that ensures safe operation of rail vehicles using data communications. In CBTC systems, less service availability could cause train derailment, collision or even catastrophic loss of lives or assets. Therefore, the availability...
Dual-Mode handsets containing both WLAN and cellular interfaces are becoming increasingly common. When moving between WLAN and cellular radio coverage,the switching of an active session from one interface to another is referred to as Vertical Handover (VHO). To provide successful VHO the WLAN link has to be maintained until the cellular connection is established. Our previous measurements of the WLAN...
The envelope pulse-width modulation (EPWM) transmitter has been proposed to address the issue of low power efficiency in the linear amplification of multicarrier signals such as the OFDM. However, the delta-sigma (Σ-Δ) modulator in the EPWM transmitter generates quantization noise that degrades signal quality. In this paper, two new EPWM architectures called the envelope subtraction EPWM (ES-EPWM)...
In this paper, we are interested in a cognitive secondary wireless local area network (WLAN) which operates in the same or overlapping spectrum and coverage with a primary wireless network. The protection of primary network is quantified by the detection time, which defines the number of superframes required for the secondary network to recognize the re-appearance of the primary network. We obtain...
The open and distributed nature of the IEEE 802.11 based wireless network makes it easy for selfish nodes to gain unfair share on the networks by manipulating the protocol parameters. In this paper, we address the detection of such selfish behavior. The two main challenges associated with the detection problem are the unknown selfish behavior strategy and real-time detection of the behavior. While...
In this paper, we compare the capacities of WiFi networks in their different possible implementations. These implementations include hierarchical WiFi/WiMAX networks where WiFi APs are connected to the Internet using WiMAX links, and WiFi mesh networks where WiFi APs may play the role of routers that send packets to other APs, acting as Internet gateways. At the packet level, we model both WiFi and...
Communication-based train control (CBTC) system is an automated control system for railways that ensures the safe operation of rail vehicles using wireless data communications. The train-ground communication system is one of the key subsystem of CBTC. CBTC systems have stringent requirements for wireless communication availability and latency. In this paper, we propose a seamless handoff scheme based...
A novel adaptive scheduling with coordination for the performance improvement of delay-sensitive applications over heterogeneous wireless networks is proposed. It can bring such contributes i) adaptation capabilities at different layers of the protocol stack, and ii) the coordinated scheduling initiation procedure. It uses information from the physical layer and data link layer to determine the appropriate...
In this paper, we consider a DTN/WLAN integrated network where nomadic nodes with high mobility comprise a delay tolerant network (DTN) while local nodes with low mobility reside in the coverage area of wireless local area networks (WLANs). A message dissemination service is considered, where data traffic is generated by a server in the Internet and destined to a group of nomadic nodes. In order to...
WLAN RSS-based localization has been a hot research topic for the last years. To obtain high accuracy in the noisy wireless channel, WLAN location determination systems usually use a calibration phase, where a radio map, capturing the signal strength signatures at different locations in the area of interest, is built. The radio map construction process takes a lot of time and effort, reducing the...
A low complexity M-algorithm based multiple-input multiple-output (MIMO) tree search algorithm with near maximum likelihood (ML) performance is proposed in this paper. Numerical examples show that our tree search algorithm is able to provide a significant performance gain over the MMSE detection. Based on this algorithm, a fully pipelined architecture is presented for the MIMO orthogonal frequency...
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