scholarly journals An Ultrasonic Object Detection Applying the ID Based on Spread Spectrum Technique for a Vehicle

Sensors ◽  
2020 ◽  
Vol 20 (2) ◽  
pp. 414
Author(s):  
Donghee Yi ◽  
Heetae Jin ◽  
Moon Chan Kim ◽  
Suk Chan Kim
Keyword(s):  
Spread Spectrum ◽  
Detection Rate ◽  
Cross Correlation ◽  
Obstacle Detection ◽  
Zero Crossing ◽  
Reflected Wave ◽  
Orthogonal Codes ◽  
Narrow Bandwidth ◽  
Barker Code ◽  
Verification Process

When an ultrasonic sensor generates an ultrasonic wave and detects an obstacle from a reflected wave, a signal transmitted by other ultrasonic sensors would be interference. In this paper, to overcome the interference, a transducer transmits a signal with a unique ID modulated. The interference is ignored by verifying that the reflected signal includes its ID. The ID verification process uses a correlation between the received signal and the ID. Therefore, the ID is selected from orthogonal codes with good cross-correlation. Long code has the advantage of being more robust to interference. However, the reflected wave from nearby obstacles might return before the transmission ends. Therefore, the 7-bit Barker code is applied for near obstacle detection and a 31-bit Gold code is used for distant obstacle detection. The modulation technique is DQPSK, which is available in a narrow bandwidth and has a simple receiver structure. In ID recognition based on correlation, a near–far problem occurs due to a large amplitude difference between the received wave and interference. The addition of a zero-crossing detector solves this problem. The hardware is implemented based on the algorithm proposed in this paper. The simulation showed a detection rate of at least 90% and the the result of the real measurement represented a detection rate of 97.3% at 0.5 m and 94.5% at 2 m.

Comparative Study on Spreading Codes

2017 ◽  
Vol MCSP2017 (01) ◽  
pp. 14-16
Author(s):  
Omprava Agasti ◽  
Sujatarani Raut ◽  
Shibashis Pradhan
Keyword(s):  
Communication Networks ◽  
Spread Spectrum ◽  
Cross Correlation ◽  
Additive White Gaussian Noise ◽  
Personal Communication ◽  
Spreading Codes ◽  
Personal Communication Networks ◽  
Transmission Data ◽  
Commercial Applications ◽  
Spread Spectrum Systems

In this paper, we studied on spreading code for wireless communication, their performance analysis, applications and its implementation. Spread-spectrum systems have found important commercial applications in CDMA cellular networks and wireless personal communication networks. Implementation is complex, mainly because spreading the baseband (by a factor that can be several orders of magnitude) forces the electronics to act and react accordingly, which, in turn, makes the spreading and dispreading operation necessary. In spread spectrum the transmission signal bandwidth is much higher than the information bandwidth. The signal occupies a bandwidth much larger than what is necessary to send the information in spread spectrum technology. CDMA uses unique spreading codes to spread the baseband data before transmission data. The performance of a CDMA system gets controlled by two types of interference, namely ISI and MAI which are the function of auto and cross correlation values of the spreading codes respectively. The existing codes using Additive White Gaussian Noise channel under multi-user has been compared with the Bit Error Rate(BER) performance.

Netted Radar System Design with Spread Spectrum Technology

2011 ◽  
Vol 55-57 ◽  
pp. 648-653
Author(s):  
Lian Qing Fu ◽  
Li Sheng Yang ◽  
Tao Wang ◽  
Qing Le Zhang
Keyword(s):  
System Design ◽  
Spread Spectrum ◽  
Cross Correlation ◽  
Mutual Interference ◽  
Radar System ◽  
Power Ratio ◽  
Emission Signal ◽  
Simulation Results ◽  
Correlation Properties

In this paper, a novel netted radar system is designed to reduce the influence of mutual interference between signals. The emission signals of all stations are assigned the orthogonal PN codes. Because of the good autocorrelation and cross-correlation properties, mutual interference becomes weaker and signals from different stations could be separated by the preassigned PN codes. At the same time, the spectrum of the emission signal is spreaded, the peak-to-mean envelope power ratio (PMEPR) and the intercepted probability of the signals descend therefore. Simulation results show the good performance of the proposed approach.

scholarly journals The Theoretical Limits of Watermark Spread Spectrum Sequence

2014 ◽  
Vol 2014 ◽  
pp. 1-6
Author(s):  
Nan Jiang ◽  
Jian Wang
Keyword(s):  
Lower Bound ◽  
Spread Spectrum ◽  
Communication Channel ◽  
Cross Correlation ◽  
Digital Watermark ◽  
Correlation Property ◽  
Random Sequences ◽  
The Cross ◽  
Peak Correlation

At present, the spread spectrum (SS) sequences used in watermark include i.i.d. random sequences and the sequences used in SS communications. They appear earlier than digital watermark. Almost no researchers pay attention to whether they are really fit for watermark. In this paper, we compare the SS watermark channel and the traditional SS communication channel. We find out that their correlation property is different. Considering cropping and translation attacks, we define watermark auto- and cross-correlation and propose Loose Autocorrelation and Tight Cross-Correlation (LAC&TCC) properties for SS watermark. The LAC&TCC properties are that, whether or not synchronized, the autocorrelation is equal or close to 1 and the cross-correlation is equal or close to 0. Accordingly, the peak correlation is divided into the peak autocorrelationRa(l)and the peak cross-correlationRc(l). We establish the lower bound ofRc(l)and the higher bound ofRa(l), respectively. The two bounds indicate that, no matter how small the cover is reserved, the extractor can always find a threshold to distinguish auto- and cross-correlation in theory.

scholarly journals Heterogeneous LPWAN Communication for Electric Vehicle Charging Infrastructure

2019 ◽  
Vol 9 (2) ◽  
pp. 2060-2067
Keyword(s):  
Smart Grid ◽  
Spread Spectrum ◽  
Ad Hoc ◽  
Data Communication ◽  
Transportation Policy ◽  
Political Polarization ◽  
Sustainable Mobility ◽  
Charging Infrastructure ◽  
Electric Vehicle Charging ◽  
Narrow Bandwidth

Many countries worldwide are set to include Electric Vehicles (EV) as a prime element in transportation policy owing to political polarization to combat climate changes. Circumstances are conducive to a sustainable mobility paradigm and have accelerated the adoption of EVs. The situation demands the deployment of charging infrastructure at a faster pace. Smart Grid provides the pervasive support for the deployment of charge stations. But the charging infrastructure should scale beyond the frontiers of metropolitan geography. The paper proposes a heterogeneous network to support mobility to EV users utilizing the paradigm of the Internet of Things (IoT). A heterogeneous ad-hoc network of Low Power Wide Area Networks (LPWAN) and mobile data communication is proposed to support mobility and scalability of the infrastructure. The proposed ad-hoc communication infrastructure utilizes LoRaWAN, a promising LPWAN technology characterized by a long-range at a narrow bandwidth. LoRaWAN employs Chirp Spread Spectrum (CSS) in its physical layer. The paper peeps into standards and protocols supporting Smart Grid and EV charge infrastructure. An SNR characteristic of LoRaWAN is simulated for suitability and Hardware for communication node is proposed.

scholarly journals Inter-Relay Interference Mitigation for Chirp-Based Two-Path Successive Relaying Protocol

Sensors ◽  
2019 ◽  
Vol 19 (15) ◽  
pp. 3346 ◽  
Author(s):  
Kwang-Yul Kim ◽  
Yoan Shin
Keyword(s):  
Spectral Efficiency ◽  
Spread Spectrum ◽  
Cross Correlation ◽  
Interference Mitigation ◽  
Data Rate ◽  
Transmission Performance ◽  
High Data ◽  
Single Relay ◽  
The Internet Of Things ◽  
Degree Of Similarity

Since the chirp spread spectrum (CSS) system is considered as a communication technology for the Internet of things (IoT), long-range communication and a high data rate are required. In wireless communications, in order to increase spectral efficiency and to extend transmission coverage, a two-path successive relaying (TPSR) protocol has been proposed. Thus, in order to improve transmission performance of the CSS system, in this paper we apply the TPSR protocol to the CSS system. However, since the TPSR protocol is successively relaying data, the spectral efficiency may be limited due to inter-relay interference (IRI). Hence, we propose a multiple linear chirp-based IRI mitigation method for the CSS-based TPSR protocol. In the proposed scheme, the cross-correlation coefficient (CCC) has been derived mathematically according to a separating bandwidth in a given total bandwidth. Then, one separating bandwidth that guarantees the transmission performance is allocated to the primary relay by considering a single relay CCC (SR-CCC) and another separating bandwidth that guarantees the orthogonality from the primary relay is allocated to the secondary relay by considering the inter-relay CCC (IR-CCC). Since the IR-CCC means a degree of similarity between these two relays, it is possible to mitigate the IRI effect within the same bandwidth by allocating orthogonal separating bandwidths to each relay. Simulation results show that the proposed scheme can improve the transmission performance by mitigating the IRI effect even in high IRI environments. Consequently, we expect that the proposed scheme can extend the transmission coverage and increase the data rate of the CSS system.

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