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The exponentially increasing number of Internet of things (IoT) devices introduces spectrum crisis to the widely used industrial, scientific, and medical (ISM) frequency band. Since IoT devices use heterogeneous radios with different bandwidths (e.g., 20 MHz for WiFi and 2 MHz for ZigBee), traditional interference avoidance methods, such as time-division multiple access (TDMA) and carrier-sense multiple...
ZigBee is a widely used wireless technology in low-power and short-range scenarios such as Internet of Things (IoT), sensor networks, and industrial wireless networks. However, the standard ZigBee supports only one data rate, 250Kbps, which thoroughly limits ZigBee's efficiency in dynamic wireless channels. In this paper, we propose Mrs.Z, a novel physical layer design to enable multi-rate selection...
In this paper, we propose an energy-harvesting based decode-and-forward multi-hop cognitive relay protocol, where secondary users harvest energy from the radio frequency signals transmitted by multiple dedicated power beacons (PBs) to support the information transmission. The secondary transmitters including source and relays must adjust their transmit power to satisfy interference power constraints...
Several frequency hopping systems can share the same frequency band using different hopping patterns. However, the risk of interference increases when there are few frequencies in the band and increases further for close co-location and out-of-band emissions from the transmitter. In this paper, we use a statistical method to analyze the impact of interference from a co-located FH system. Different...
A novel distributed scheduling method for minimizing packet routing delays in multi-hop multi-band cognitive radio networks is proposed. The proposed scheduling method exploits spectral awareness in the form of spatial potential fields that characterize sources of interference as repulsive forces and packet destinations as attractive forces. The proposed scheduling protocol operates in four phases,...
This paper proposes a Mobility and Activeness aware Relay Selection (MARS) algorithm for multi-hop D2D communication underlaying cellular networks. MARS takes into account the activeness and mobility of a user device in relay selection, and introduces an activeness factor and a mobility factor in calculating the utility gain of the system brought by a relay candidate. To select a relay for a pair...
The ultimate goal of the Internet of Things (IoT) paradigm is to provide seamless connectivity of low power wireless devices to the Internet Protocol network. Cooperative Beamforming (CB) has been proposed as a technique that can enable low power wireless communication by allowing a collection of devices to transmit data simultaneously to a network aggregator in one hop. Apart from traditional CB...
In this paper, we focus on the design and analysis of channel access in vehicular ad hoc networks (VANETs) for event-driven multi-hop safety services. First, a novel channel access scheme that incorporates an application-level distance (timer)-based rebroadcast is designed to enhance the reliability and efficiency of safety message delivery. In the scheme, an effective new approach integrating transmitter-oriented...
Based on Parallel Combinatory Spread Spectrum (PCSS) communication system, an improved PCSS system is proposed with PN sequences serial-parallel combinatory connecting. Using the character of internal memory between information data, optimization treatment is done in the receiver. The system model is built and simulated in AWGN channel, and the properties and error bit probability are discussed. The...
In the IEEE 802.15.4-2015 standard, Time Slotted Channel Hopping (TSCH) aims to guarantee high-level network reliability by keeping nodes time-synchronised. In order to ensure successful communication between a sender and a receiver, the latter starts listening shortly before the expected time of a MAC layer frame's arrival. The offset between the time a node starts listening and the estimated time...
In this paper, a minimax anti-jamming strategy in a frequency hopping spread spectrum (FHSS)/quadrature phase-shift keying (QPSK) satellite communication system is developed. The goal of the anti-jammer is to minimize symbol error probability while that of the jammer is to maximize it. The jammer attacks legitimate communication system via two jamming strategies: single-tone jamming and full-band...
Spread spectrum communication systems can require significant computation to perform initial acquisition, searching across time and frequency to accurately detect and lock onto the desired signal. This initial acquisition problem is exacerbated in deeply spread non-binary signals lacking cyclostationary features or repetitive codes, leading to a desire for less computationally intensive approaches...
A novel efficient blind estimation method is proposed for long-code direct sequences spread spectrum signals. The core idea of the proposed method is to construct an information symbol transition pattern matrix to eliminate the information symbol time varying damage to the periodic structure of pseudo-noise sequences for long-code DSSS signals. Then eigenanalysis approach is employed to estimate the...
This paper considers the problems of efficiency estimation of using different types of modulation of hydroacoustic signals of AUV communication, navigation and control systems. The types of signal were investigated: simple signal, linear frequency modulation signal and direct sequence spread spectrum. The signals were compared by the noise immunity, time resolution and detection probability with usage...
Many works attributed the successful reception of concurrent transmission (CT) to the constructive interference. However, due to the inevitable carrier frequency offset (CFO) and the resulted beating effect, the claim of constructive interference is actually not valid. To clarify the reason behind the successful receptions under CT, we conduct extensive evaluations and identify the following findings...
In this contribution, a cyclic-TDOA methodology is simulated. The simulation is a preliminary study that would allow to design and to implement an indoor optical-positioning system relaxing the synchronization requirements among receivers. The synchronism requirement relaxations are carried out by the modification of the structure of the positioning system considering an emitter beacon formed with...
A cost effective approach for better communication to overcome the near-far problem in CDMA system in case of Direct Sequence Spread Spectrum (DSSS) multiuser system instead of single user is depicted in the paper. The need for improvement of the hearability problem in modern telecommunication system has huge applications in security section. A comparative study of Bit Error Rate (BER) vs Signal to...
Interference between frequency hopping (FH) systems sharing the same frequency band can decrease the communication performance. The decrease can be severe, especially for systems on the same platform or in the vicinity of each other. Interference can stem both from sharing the same frequency channel momentarily or from adjacent channels. It is shown that a devastating high error floor can appear when...
In this paper a Direct Sequence Spread Spectrum (DSSS) based offline wireless white light communication system is established. Field measurements are conducted to compare the performance with and without DSSS. The experimental results show that the DSSS is able to improve performance obviously.
A major challenge for data transmission in wireless multihop networks is to efficiently utilize the present channel capacity provided by the variety of links within the network. To achieve this, we combine the concept of opportunistic routing with rateless coding and Orthogonal Frequency Division Multiple Access (OFDMA). Opportunistic routing exploits the broadcast nature of wireless transmissions...
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