Nominal Bit Research Articles

A Highly Stable Physically Unclonable Function Using Algorithm-Based Mismatch Hardening Technique in 28-nm CMOS

Physically unclonable function (PUF) is an emerging security solution for Internet of Things (IoT) devices. However, PUF faces a critical design challenge: responses should remain the same regardless of environmental conditions. This article presents an algorithm-based mismatch hardening technique that provides an effective and efficient solution to stabilizing PUF responses, which could be applied to various PUF circuits. The proposed stabilization technique combines multiple mismatches to achieve high reliability with minimum loss of utility. Moreover, the proposed approach requires only the available digitized PUF responses, avoiding any auxiliary measurement circuit to minimize additional implementation and testing overhead. The PUF test chip implemented in 28-nm CMOS technology shows that the proposed stabilization technique achieves a highly stable performance, lowering the nominal bit error rate (BER) to 0.0016%. It also exhibits excellent reliability with a worst-case BER of 0.16% across 0.7 to 1.2 V and −50 to 125°C, proving to be a promising candidate for security primitive for IoT applications.

Influence of PDC bit cutter layout on stick–slip vibrations of deep drilling systems

This paper extends the class of two degrees-of-freedom (2 DOF) models that simulate the self-excited vibrations of a rotary drilling system, by considering PDC bits equipped with round cutters and a realistic cutter layout. The extension requires an elaborate bit/rock interaction model that involves bit characterization, cutter projection and correlating the bit/rock engagement with the bit motion history. The governing equations are state-dependent delay differential inclusions with two major sources of nonlinearities: the regenerative effect in both cutting and frictional components of the drilling force and the unilateral nature of the frictional force. To solve for the state variables, the technical challenges involve a search of many delays and a fast and accurate geometric computation, which are respectively resolved with a modified inverse algorithm and the polygon clipping technique. The linear stability analysis is formulated based on the geometric variations of the bit/rock engagement surfaces, which result in critical rotation speeds that separate various stability regions of the decoupled axial dynamics. Determined by the bit design, the resulting stability boundaries are defined in terms of the rotation speed and the nominal bit penetration per revolution. With the time simulation, it is verified that the stability map, in conjunction with the exact location of unstable axial poles, can be used to predict the occurrence of axial stick–slip oscillations in the coupled dynamics, which eventually lead to sustained torsional stick–slip oscillations.

Systematic literature survey: applications of LoRa communication

LoRa is a communication scheme that is part of the low power wide are network (LPWAN) technology using ISM bands. It has seen extensive documentation and use in research and industry due to its long coverage ranges of up-to 20Km or more with less than 14dB transmit power. Moreover, some applications report theoretical battery lives of upto 10years for field deployed modules utilising the scheme in WSN applications. Additionally, the scheme is very resilient to losses from noise, as well bursts of interference through its FEC. Our objective is to systematically review the empirical evidence of the use-cases of LoRa in rural landscapes, metrics and the relevant validation schemes. In addition the research is evaluated based on (i) mathematical function of the scheme (bandwidth use, spreading factor, symbol rate, chip rate and nominal bit rate) (ii) use-cases (iii) test-beds, metrics of evaluation and (iv) validation methods. A systematic literature review of published, refereed primary studies on LoRa applications was conducted. Using articles from 2010-2019. We identified 21 relevant primary studies. These reported a range of different assessments of LoRa. 10 out of 21 reported on novel use cases. As an actionable conclusion, the authors conclude that more work is needed in terms of field testing, as no articles could be found on performance/deployment in Botswana or South Africa despite the existence of LoRa networks in both countries. Thus researchers in the region can research propagation models performance, energy efficiency of the scheme and MAC layer as well as the channel access challenges for the region.

Fully-Coherent Reader With Commodity SDR for Gen2 FM0 and Computational RFID

There has been a continuously growing interest in radio frequency identification (RFID) and more recently, in computational RFID, i.e. battery-less sensors that piggyback sensed information, rather than a constant ID bit stream, utilizing Gen2, the physical layer of commercial RFID systems. This work offers a complete software-defined radio (SDR) reader with 1) coherent detection without rate degradation, by exploiting already present preambles in Gen2; 2) full exploitation of FM0 line coding memory in Gen2 tags; 3) careful handling of symbol synchronization and departure of commercial tags from nominal bit duration; and 4) implementation and testing of Gen2 in a commodity SDR, utilizing a single transceiver card. Continuing recent work, this contribution offers an updated prototyping tool that could further unlock the potential of computational RFID and relevant battery-less sensor networks.

Idle sense

We consider wireless LANs such as IEEE 802.11 operating in the unlicensed radio spectrum. While their nominal bit rates have increased considerably, the MAC layer remains practically unchanged despite much research effort spent on improving its performance. We observe that most proposals for tuning the access method focus on a single aspect and disregard others. Our objective is to define an access method optimized for throughput and fairness, able to dynamically adapt to physical channel conditions, to operate near optimum for a wide range of error rates, and to provide equal time shares when hosts use different bit rates.We propose a novel access method derived from 802.11 DCF [2] ( Distributed Coordination Function ) in which all hosts use similar values of the contention window CW to benefit from good short-term access fairness. We call our method Idle Sense , because each host observes the mean number of idle slots between transmission attempts to dynamically control its contention window. Unlike other proposals, Idle Sense enables each host to estimate its frame error rate, which can be used for switching to the right bit rate. We present simulations showing how the method leads to high throughput, low collision overhead, and low delay. The method also features fast reactivity and time-fair channel allocation.

NMR-melting-curve study of bitumen of different types and origin

The nuclear magnetic resonance (NMR) melting-curve method, employing measurement of the temperature-dependent width of the1H NMR spectrum, was used in a comparative study of softening of various industrial bitumen types (BIT 60 and BIT 90) produced by different manufacturers. Out of three manufacturers involved in the study, only the bitumen samples of one of them exhibited the expected regularity — the NMR melting curves formed two well-defined groups, one belonging to BIT 60-type samples and the other to BIT 90-type, and the BIT 90 samples showed softer melting characteristics. This indicates a reproducible industrial production process and reliable classification into different bitumen types. The NMR melting curves of nominal BIT 60-type samples of the other two manufacturers are scattered irregularly over a large range, extending much beyond the total span of the BIT 60 and BIT 90 curves of the first manufacturer. Hence the classification of these samples into one bitumen type (BIT 60) makes less sense.

Beyond 3G: wideband wireless data access based on OFDM and dynamic packet assignment

The rapid growth of wireless voice subscribers, the growth of the Internet, and the increasing use of portable computing devices suggest that wireless Internet access will rise rapidly over the next few years. Rapid progress in digital and RF technology is making possible highly compact and integrated terminal devices, and the introduction of sophisticated wireless data software is making wireless Internet access more user-friendly and providing more value. Transmission rates are currently only about 10 kb/s for large cell systems. Third-generation wireless access such as WCDMA and the evolution of second-generation systems such as TDMA IS-136+, EDGE, and CDMA IS-95 will provide nominal bit rates of 50-384 kb/s in macrocellular systems. This article discusses packet data transmission rates of 2-5 Mb/s in macrocellular environments and up to 10 Mb/s in microcellular and indoor environments as a complementary service to evolving second- and third-generation wireless systems. Dynamic packet assignment for high-efficiency resource management and packet admission; OFDM at the physical layer with interference suppression, space-time coding, and frequency diversity; as well as smart antennas to obtain good power and spectral efficiency are discussed in this proposal. Flexible allocation of both large and small resources also permits provisioning of services for different delay and throughput requirements.

HUBNET performance measurement

Media-access delays in HUBNET, a high-performance local area network, are examined. An experimental technique for loading such a network with data up to 97.5% of its nominal bit rate is described. The results of a series of measurements of the packet-access delay in a network operating at loads up to 87.5% of capacity are presented. A modeling technique for this process is developed, and the results of calculations based on that model are compared to the experimental results. Extremely good agreement is obtained. The model is then used to examine the network behavior comprehensively over an extensive range of parameters.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A comparison of data modulation techniques for land mobile satellite channels

Several modulation schemes for transmitting data over land mobile satellite channels are compared using a Monte Carlo simulation. Schemes under consideration include differentially detected minimum shift keying (DMSK), differentially detected filtered offset quadrature phase shift keying (DOQPSK), and coherently detected binary phase shift keying with transparent tone-in-band processing (BPSK-TTIB). The transmission of data to and from a mobile radio, which is also capable of operating as an amplitude companded single sideband radio, is the application considered here. The nominal bit rate is 2400 bit/s, while the nominal channel spacing is 5 kHz. DOQPSK with nonredundant single-error correction (SEC) is shown to be a promising candidate. It is capable of outperforming DMSK with SEC by more than 1 dB. Techniques that send a reference signal along with a PSK signal and then perform coherent detection, such as BPSK-TTIB, are also shown to be inferior to DOQPSK with SEC for the class of channels considered here.