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Rendezvous and Multi-channel Hidden Terminal problems are the two well-known challenges in developing a multi-channel MAC protocol. In literature, the Control Period Based (CPB) approach is proposed to cope with the rendezvous problem. Each channel is partitioned into several beacon intervals and each of which consists of ATIM window and data window. All hosts are asked to stay in every ATIM window...
The article proposes a new type of short-range wireless information transmission equipment. It is mainly composed of a transmitter and a receiver. The transmitter and the receiver all use the high integrated and high performance single chip solution. The transmitter is only composed of pure hardware. It features simple structure, stable performance and simple debugging. The receiver not only has simple...
Wireless Sensor Networks (WSNs) consist of small nodes with sensing, computation, and wireless communication capabilities. Wireless Sensor Network (WSN) is a promising data mining solution for precision agriculture. Instrumented with wireless sensors, it will become available to monitor the plants for real time, such as air temperature, soil water content, and nutrition stress. This real time information...
The main bottleneck to achieve energy autonomy in body area networks (BAN) is the design of an ultra low power yet reliable wireless system. In this paper, we first demonstrate the feasibility of an ultra low power receiver by presenting our implemented receiver chip that could operate on a total power of 479.5 uW, which is more than one order of magnitude lower than commercially available low power...
This paper proposes an adaptive bandwidth control scheme for autonomous distributed networks. Based on the consideration that the carrier sense multiple access with collision avoidance (CSMA/CA) is not efficient in terms of throughput due to its strict collision avoidance process, this paper employs a dynamic spectrum control (DSC) in which a certain number of discrete spectra having the highest signal...
This paper addresses the spectrum-sharing for wireless communication with a licensee-primary and a secondary users interfering with each other. We propose a new practical power control policy for the secondary user, under outage performance requirements for both users, with partial knowledge of channel state information.
We study the physical layer design of a distributed time-division multiple access (TDMA) protocol for wireless body area networks (WBAN). The distributed TDMA scheme is derived from a bio-inspired algorithm known as Pulse-Coupled Oscillator (PCO), in which each node in the network updates its state based on its knowledge of the neighborhood. ON-OFF ultra wide band (UWB) modulation is used by the sensors...
Recent security methods propose to generate secret keys from Ultra Wide Band (UWB) channels. These solutions rely on the reciprocity and spatial channel correlation principles. This work aims at presenting empirical studies on the aforesaid properties. First, we verify the UWB reciprocity for different multipath scenarios. In these experiences, the reciprocity is always valid independently of distance...
In this paper indoor wireless Infrared (IR) technology for healthcare monitoring is studied. Monitoring provides a continuous and reliable vital sign measurement to secure patient staying in the hospital. Considering that patient moving is inevitable, we focus on a mobile IR channel based on diffuse propagation. A model of mobile channel is developed through the study of statistical distributions...
The 60 GHz technology has an immense potential to provide wireless communication at multi-gigabit rates. At 60 GHz frequency band, severe attenuation of the signals can significantly degrade communication performance. To cope with the attenuation problem, directional antennas with high directive gains can be utilized. When network nodes use directional antennas, the neighbor discovery process becomes...
Since the pioneering research work of Ahlswede et al. in 2000, Network Coding (NC) has rapidly emerged as a major research area in electrical engineering and computer science due to its wide applicability to communication through real networks. The many contributions available in the literature to date, ranging from pure theoretical studies on fundamental limits to practical experimentations in real-world...
In Wireless Local Area Networks (WLANs), the estimation of interference conditions at a receiving node and the determination of interference relations among different wireless nodes is a challenging problem. Interference relations provide the information of which wireless links do interfere if activated concurrently. This information is crucial for the determination of which wireless links are allowed...
In this paper, we briefly describe the wireless sensor network(WSN), and highlight the design of RF antenna with a gain based on nRF905 chip, then complete an intelligent greenhouse monitoring system for agricultural greenhouse temperature based on WSNs. Finally, we confirm the feasibility of the system design through some tests.
In this paper, we deal with the time slot allocation in time-hopping ultra-wide band (TH-UWB) ad-hoc networks in order to maximize the total sum rate. This problem is known to be a discrete NP-hard optimization problem and hence cannot be solved with a computationally efficient algorithm. Moreover, the sum rate maximization often leads to starvation of links experiencing bad channel conditions. Our...
Vehicular ad hoc networks play a critical role in enabling important active safety applications such as cooperative collision warning. These active safety applications rely on continuous broadcast of self-information by all vehicles, which allows each vehicle to track all its neighboring cars in real time. The most pressing challenge in such safety-driven communication is to maintain acceptable tracking...
This paper presents results of experiments on characterization of wireless channels inside a tall building in Hung Hom, Hong Kong with the transmitter located atop the DE Block of the Hong Kong Polytechnic University and the channel measurements are made inside a nearby tall residential building. The channel probing signal centered at 1.8 GHz had a bandwidth of 60 MHz. The results were analyzed for...
This paper proposes a new combinational technology which is feasible to apply physical-layer network coding (PNC) to wireless fading channel. The key step of PNC is that sources broadcast signals simultaneously without orthogonal scheduling. Naturally, the signals overlap in the free space at the receivers. Since the signals from different sources are mutual independent, rooted on this rational assumption,...
Due to the complexity and time-variation of wireless channel, it is a great challenge to measure and estimate the channel quality accurately in wireless ad hoc network. To address this problem, we propose a link quality estimator which use the packet loss rate (PLR), round trip time (RTT), available bandwidth (ABW) at the sender and the feedback information from receiver to continuously tracks the...
We propose a spectrum sharing policy based on signal-to-interference-noise ratio (SINR) at a primary receiver. Contrast to the conventional spectrum sharing policy based on full channel state information (CSI) feedback, in our spectrum sharing policy, a secondary link can share the primary user's spectrum only using a binary state feedback for the interference link between a secondary transmitter...
This work will address the challenges to facilitate the development of a high capacity radio system for a small, miniaturized electronic pill device that can be swallowable or implantable in human body in order to detect biological signals or capture images that could eventually be used for diagnostic and therapeutic purposes. In addition to reviewing and discussing the recent attempts in electronic...
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