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The objective of this work is the design of a 32×32 element X-band reflectarray, in which the re-radiated elements have no conventional shape and enough degrees of freedom to compensate both the spatial and frequency phase variation of the re-radiated field. In particular, here we focus on a re-radiating element consisting in two concentric square rings in which two different and quite independent...
The paper presents the concept, design and analysis for a visible light communications receiver which has a full 180° perception angle thus offering the guard against blocking and enhancing the system mobility. The proposed receiver includes seven sub-receivers with the proposed geometrical shape investigated and analyzed in MATLAB® for evaluating the received power, RMS delay spread and corresponding...
We propose a resources reservation scheme pro-vides QoS for handing over stations within Mobile Multi-hop Relay Networks. The original time interval between two consecutive scans is divided into multiple intermediate time intervals for scan or transmission/reception. On the light of the intermediate scan results and depending on the "Mobility Context " of the SS or the mobile RS, the reservation...
Data request task scheduling is one of the important issues for P2P VoD systems. However the existing data scheduling strategies in P2P VoD system is not fair enough. They make many nodes, which upload data actively, bear very heavy load, while those selfish nodes providing no resource sit idle. This paper presents an admission control strategy on serving nodes combining with the incentive mechanism...
A 1 GS/s Continuous-time Delta-Sigma modulator (CT-ΔΣM) with 31 MHz bandwidth, 76.3 dB dynamic range and 72.5 dB signal-to-noise is reported in a 0.13µm CMOS technology. The design employs an excess loop delay (ELD) of more than one clock cycle for achieving higher sampling rate. The ELD is compensated using a fast-loop formed around the last integrator by using a sample-and-hold. Further, the effect...
Scalable multicast protocol design based on the Bloom filter has received much attention from the research community recently. With the Bloom filter-based design, routing information is carried by the multicast data packet in the format of a Bloom filter. As the network node has no need maintaining a forwarding state for each group it is supporting, the Bloom filter-based multicast protocols are more...
The existing energy saving algorithms are implemented only with one kind of Passive Optical Network (PON). However, as far as Ethernet PON (EPON), good performances can not be reached simultaneously in both 10G-EPON and 1G-EPON. 10G-EPON can provide higher throughput and lower delay than 1G-EPON, but it consumes more energy. Therefore, to obtain trade-off performances, we propose a new Energy Saving...
Geographically distributed data centers for the rapid growth of worldwide cloud service bring the demand of massive inter-data center information exchange. Considering the capacity and costs, existing optical networks show their advantages to carry the non-interactive, delay tolerated and bulk inter-data center data. In order not to affect the real-time traffic, these bulk data is usually transferred...
In mobile cognitive radio networks, the expected delay for a packet to be delivered to its destination via a singlehop communication (without relaying) is a fundamental metric that can provide a guidance to multi-hop routing protocol design and route planning. In this paper, we characterize the impact of PU activities, spectrum availabilities, channel bandwidth, MAC access, SU mobilities, and interference,...
We consider the problem of placing virtual clusters, each consisting of a set of heterogeneous virtual machines (VM) with some interrelationships due to communication needs and other dependability-induced constraints, onto physical machines (PM) in a large data center. The placement of such constrained, networked virtual clusters, including compute, storage, and networking resources is challenging...
In recent years, Peer-to-Peer (P2P) multimedia streaming has become an alternative to cable/satellite TV services. Many P2P streaming applications further provide users with DVD-like operations: play, pause, chapter selection, fast-forward, and rewind. Such a real-time interactive multimedia streaming is commonly referred to as the P2P Video-on-Demand (VoD). To further improve the streaming quality,...
This paper demonstrates the effectiveness and robustness of amplifier finite gain bandwidth compensation within a wideband third order continuous time delta sigma modulator and the effects of process, mismatch and temperature on modulator stability. In many state of the art designs, GBW is kept safely above the sampling frequency of the modulator, which suffers a power penalty especially for high-speed...
Recent advances in ADCs have enabled the development of low power receivers for wireless communication applications. In this paper we will discuss a specific class of ADCs, namely sigma delta ADCs. A brief overview of challenges in the design of these ADC's will be discussed along with the recent advances and techniques in overcoming these challenges. Two specific examples in the context of narrow...
Continuous-time delta sigma (CT-ΔΣ) ADCs are established as the data conversion architecture of choice for the next-generation wireless applications. Several efforts have been made to simultaneously improve the bandwidth and dynamic range of ΔΣ ADCs. We proposed using two-step quantizer in a single-loop CT-ΔΣ modulator to achieve higher conversion bandwidth. This paper presents a tutorial for employing...
In this paper, the scheduling problem of the network with limited bandwidth is considered. In order to improve the network quality of service and the quality of control simultaneously, an intelligent feedback scheduling method is proposed. The scheduler reschedules the priority, the sampling period, and the output threshold concurrently according to the control authority of each node, which is calculated...
Due to diverse network latencies, participants in a Distributed Virtual Environment (DVE) may observe different inconsistency levels of the simulated virtual world, which can seriously affect fair competition among them. In this paper, we investigate how to disseminate Dead Reckoning (DR)-based updates with the objectives of achieving fairness among participants and reducing inconsistency as much...
IEEE 802.15.4 is a standard of Low-Rate Wireless Personal Area Network (LR-WPAN), which provides the communications in short distance, low data rate, low power consumption. In IEEE 802.15.4 a guaranteed time slot (GTS) structure is defined to support high quality of service (QoS) to time-critical traffic. However, the transmission bandwidth of GTS may be wasted because of the inefficient allocation...
Machine Type Communication (MTC), which allows different devices to communicate without the needs of human to machine interactions, has been developed in recent years. However, MTC possibly resulting in an unexpectedly high collision rate is different from contemporary mobile communication service when it involves a very large number of communication terminals with little traffic requirement. As a...
Although video conferencing and its related applications have grown into a significant research area, the limited scalability of conference size is still a major problem. In this paper, a range of strategies for real-time area of interest (AOI) management in a 3D immersive video conference (IVC) are evaluated with the objective of minimising the required video transmission capacity and hence maximising...
Based on IEEE 802.15.4, a contention-free period (CFP) adopts guarantee time slot (GTS) mechanism to ensure each device can access the radio channel. However, it is hard to get the authority to access the radio channel due to more competitors access the radio channel simultaneously. To cope with this issue, we proposed a guarantee time slot mechanism to enhance the performance and utilization of using...
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