Efficient coding schemes for low‐rate wireless personal area networks

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/166246/1/cmu2bf01608.pd

Design of zigbee transceiver for IEEE 802.15.4 using matlab/simulink

ZigBee technology was developed for a wireless personal area networks (PAN), aimed at control and military applications with low data rate and low power consumption. This thesis is mainly focusing on development of Matlab/Simulink model for ZigBee transceiver at physical layer using IEEE 802.15.4. ZigBee is a low-cost, low-power, wireless mesh networking standard. First, the low cost allows the technology to be widely deployed in wireless control and monitoring applications. Second, the low power-usage allows longer life with smaller batteries. Third, the mesh networking provides high reliability and more extensive range. The work presented here is to show how we can implement ZigBee transceiver with its specifications by using Matlab/simulink, without using complex mathematical blocks. A ZigBee chip can tested and prepared by shifting the whole work from matlab environment to cadance environment. This can be done by HDL languages like Verilog HDL. Here, Minimum Shift Keying (MSK) modulation technique is described, an analysis of which shows that the theoretical maximum bandwidth efficiency of MSK is 2 bits/s/Hz which is same as for Quadrature Phase Shift Keying (QPSK) and Offset Quadrature Phase Shift Keying (Offset QPSK). The implementation clearly confirms the viability of theoritical approach. Results show that OQPSK modulation with half sine pulse shaping is perfectly employed ZigBee technology

Minimal Error IEEE 802.15.4 Communication Module for Heart Monitoring Data Transmission in IoT

With an estimation of 20 billion devices being connected to the Internet in the coming years, the accuracy and the robustness of the wireless communication modules takes the center stage. The health-care scenario, due to its critical nature, calls for an error free communication. IEEE 802.15.4 is the established standard in the Internet of Things scenario that uses Direct Sequence Spread Spectrum - Offset Quadrature Phase Shift Keying (DSSS-OQPSK) modulation. In this paper, we propose a modified minimal error IEEE 802.15.4 communication system for the IoT applications in health care. The proposed architecture uses Maximum Likelihood based frequency offset estimator that can compensate upto 80ppm of the frequency offset. The detection of the symbols is achieved by the complex correlation of the spread sequence. The Bit Error Rate (BER) performance of the proposed architecture is significantly improved compared to the standard architecture. For example, at BER of 0.01, it achieves a gain of 2db over the standard. The proposed ML estimator for frequency offset performs better in terms of error variance than the existing estimators for IEEE 802.15.4

Robust interference cancellation for differential quadrature phase-shift keying modulation with band limiting and adaptive filter

Differential quadrature phase-shift keying (DQPSK) modulation techniques and their variants are widely applied in digital communication, such as for high-speed optical fiber, bluetooth, or satellite communication. In its implementation, DQPSK cannot be separated from the potential harmful interference. In this research, a system model has been made for observation and analysis of the interference cancellation process. Discrete finite-duration impulse response (FIR) filters for band limiting and adaptive filter are the key components of the supporting block for this system model. Robust Simulink results have shown a significant increase in system performance in the existence of these key components. The indication has been shown by the best bit error rate (BER) of 3.3e-05. Constellation and eye pattern diagrams have supported the BER

IoT Networking: Path to Ubiquitous Connectivity

University of Minnesota Ph.D. dissertation. August 2019. Major: Computer Science. Advisor: Tian He. 1 computer file (PDF); xii, 105 pages.Internet of Things (IoT) is upon us with the number of IoT connected devices reach- ing 17.68 billion in the year 2016 and keeps an increasing rate of 17%. The popularity of IoT brings the prosperity and diversity of wireless technologies as one of its founda- tions. Existing wireless technologies, such as WiFi, Bluetooth, and LTE, are evolving and new technologies, such as SigFox and LoRa, are proposed to satisfy various needs under emerging application scenarios. For example, WiFi is evolving to provide higher throughput with the novel 802.11ac technology and the Bluetooth SIG has proposed the Bluetooth Low Energy (BLE) technology to support low-power applications. However, wireless technologies are victims of their own success. The vastly increasing wireless devices compete for the limited wireless spectrum and result in the performance degradation of each device. What makes it worse is that diverse wireless devices are using heterogeneous PHY and MAC layers designs which are not compliant with each other. As a result, sophisticated wireless coordination methods working well for each homogeneous technology are not applicable in the heterogeneous wireless scenario for the failure to communicate among heterogeneous devices. This dissertation aims at fundamentally solving the burden of communication in today’s heterogeneous wireless environment. Specifically, we try to build direct communication among heterogeneous wireless technologies, referred to as the cross-technology communication (CTC). It is counter-intuition and long believed impossible, but we find two opportunities in both the packet level and physical (PHY) layer to make the challenging mission possible. First, wireless devices are commonly able to do energy-sensing of wireless packets in the air. Energy sensing is capable to figure out packet-level information, such as the packet duration and timing. Based on the energy-sensing capability, we design DCTC, a CTC technology that piggybacks cross-technology messages within the timing of transmitted wireless packets. Specifically, we slightly perturb the timing of packets emitted from a wireless device to form detectable energy patterns to establish CTC. Testbed evaluation has shown that we can successfully transmit information at 760bps while keeping the delay of each packet no longer than 0.5ms under any traffic pattern. Second, in the PHY layer, high-end wireless technologies are flexible, i.e., a larger symbol set, in the modulation and demodulation. With careful choices of symbols, those wireless technologies are able to emulate and decode the PHY layer signal of a low-end one. We propose two systems BlueBee and XBee which aim at building direct com- munication between two heterogeneous IoT technologies, Bluetooth and ZigBee, with the idea of signal emulation and cross-decoding respectively. The former achieves signal emulation by carefully choosing the Bluetooth payload bits so that the output signal emulates a legitimate ZigBee packet which can be successfully demodulated by a com- modity ZigBee devices without any changes. The latter proposes a general method to support the bidirectional communication in the PHY-layer CTC by moving the complex- ity to the high-end receiver for the demodulation of signal from a low-end transmitter. Our testbed evaluation has shown that our technologies successfully boost the data rate of the state of the arts by over 10,000x times, which is approaching the ZigBee standard. This result makes CTC possible to play more roles in real-time applications, such as network coordination. In summary, this dissertation provides a new communication paradigm in a heteroge- neous wireless environment, which is to provide direct communication for heterogeneous wireless devices. Such communication is built upon two opportunities: (i) wireless de- vices are capable to sense energy in the air so that specifically designed energy patterns can transmit cross-technology information; (ii) a high-end wireless technology is more flexible and possible to emulate and demodulate the signal from a low-end technology for communication. The technologies developed in the dissertation will be the build- ing blocks for the future designs of efficient channel coordination and ubiquitous data exchange among heterogeneous wireless devices

Physical Layer Watermarking of Direct Sequence Spread Spectrum Signals

Security services and mechanisms in wireless networks have long been studied and developed. However, compared to upper network layers, physical layer security did not play a signicant role in the OSI security model. Thanks to the easier implementation and verication methods brought by the development of software dened radio (SDR) techniques, physical layer security mechanisms have recently drawn increasing interest from researchers. Digital watermarking is one of the popular security techniques that can fully utilize various exclusive characteristics of the physical layer. This thesis proposes a physical layer watermarking technique named Water-marked Direct Sequence Spread Spectrum (DSSS) or WDSSS technique, which embeds authentication information into pseudonoise (PN) sequences of a DSSS system. The design and implementation of the WDSSS prototype system on the GNU Radio/USRP SDR platform is discussed, as well as two watermark embedding methods, the maximized minimum distance method and the sub-sequence method. Theoretical analysis and experimental results on the WDSSS prototype system are presented to evaluate the performances of both the content signal and the watermark signal. Results show that, for the 11-chip PN sequence, increasing articial chip errors has aquantitatively predictable impact on the content signal, requiring 2 dB higher signal-to-noise ratio (SNR) to maintain an acceptable packet error rate (PER) for one additional ipped chip. In terms of the watermark signal, the two embedding methods demonstrated individual advantages in either PER or throughput. The maximized minimum distance method outperforms the sub-sequence embedding method with a 3 dB lower SNR requirement, while the latter provides 400 more throughput than the former with adequate SN

Ultra Low Power IEEE 802.15.4/ZIGBEE Compliant Transceiver

Low power wireless communications is the most demanding request among all wireless users. A battery life that can survive for years without being replaced, makes it realistic to implement many applications where the battery is unreachable (e.g. concrete walls) or expensive to change (e.g underground applications). IEEE 802.15.4/ZIGBEE standard is published to cover low power low cost applications, where the battery life can last for years, because of the 1% duty cycle of operation. A fully integrated 2.4GHz IEEE802.15.4 Compliant transceiver suitable for low power, low cost ZIGBEE applications is implemented. Direct conversion architecture is used in both Receiver and Transmitter, to achieve the minimum possible power and area. The chip is fabricated in a standard 0.18um CMOS technology. In the transmit mode, the transmitter chain (Modulator to PA) consumes 25mW, while in the receive mode, the iv receiver chain (LNA to Demodulator) consumes 5mW. The Integer-N Frequency Synthesizer consumes 8.5mW. Other Low power circuits are reported; A 13.56 Passive RFID tag and a low power ADC suitable for Built-In-Testing applications

Drahtloses Low Power Wide Area Network bei 2,4 GHz

Im Rahmen dieser Arbeit wird ein neues Modulationsverfahren für Low Power Wide Area Networks auf Basis von Spatial Modulation und CDMA vorgeschlagen und untersucht. Nach einem kurzen Überblick über den Stand der Technik und die Grundlagen von DSSS-Systemen wird das neue Modulationsverfahren SpaRSe (Spatial Modulation for Long Range Sensor Networks) vorgestellt, das die Vorteile von Mehrantennentechnologien mit einfacher Modulation und geringem Hardwareaufwand verbindet. Simulative Untersuchungen zeigen die erheblichen Gewinne, die durch die Verwendung SpaRSe im Vergleich zu bereits standardisierten Wellenformen erreicht werden können. Um das Potenzial und die Anwendungsnähe zu unterstreichen, werden darüber hinaus eine Implementierung auf einem Software Defined Radio vorgestellt und Ergebnisse von Kanalmessungen im urbanen Umfeld bei 2,4 GHz präsentiert. Die Auswertung der Interferenzsituation wie auch der Ausbreitungseigenschaften der Funkkanäle liefern dabei wichtige Erkenntnise zu den zu erwartenden Reichweiten eines solchen Systems. Es zeigt sich außerdem, dass die zuvor getroffenen Simulationsannahmen gerechtfertigt sind und SpaRSe auch unter realistischen, suboptimalen Bedingungen sehr robust und dem aktuellen Stand der Technik deutlich überlegen ist

Frequency Response of an Agricultural Fence and the Implications for Data Transmission

The electric fence has been used as a data transmission medium in Gallagher Products for a number of years. This has allowed the energizer to be remotely controlled and, with the current generation, to monitor the performance of the fence remotely. Very little investigation has been conducted into determining the optimum frequency bands to transmit in to give optimum performance. We propose that the fence spectrum be split into three frequency bands. A Fence Pulse Guard Band which extends from DC to 10 kHz, a Low Frequency Channel which extends from 10 kHz to 250 kHz, and a High Frequency Channel which extends from 250 kHz to 10 MHz. The fence frequency response is dependent on the length of the fence and is dominated by transmission line effects and radiative losses. For the test fence, the spectrum up to 250 kHz is flat without any frequency selective fading. Above 250 kHz, the spectrum is very unstable and the frequency selective fading can exceed 15 dB. Operating in this region requires an advanced system to utilise the available bandwidth. The impedance of the human operator in the system is best characterised as a fractional capacitor in series with a resistor. Higher frequencies are attenuated less up to 10 MHz after which the impedance is dominated by the resistance. The impedance of an insulating joint is best characterised as a capacitor in series with a resistor. Higher frequencies are attenuated less and are the preferred method for reducing the effect of insulating joints. The Low Frequency Channel is suitable for less robust systems which cannot tolerate frequency selective attenuation. The High Frequency Channel is suitable for robust systems which prioritise performance. We present a number of possible solutions for improving the efficiency of the modulation and error correction strategies. Solution 3 utilising Phase Shift Keying (PSK) with eight symbols and Trellis Code Modulation (TCM) is recommended as the first solution to be implemented and evaluated. A forward error correction strategy as outlined in Solution 1 is also recommended for implementation first. This research suggests that the electric fence system could be significantly improved in performance and reliability using the methods mentioned above but at some cost