Odd Bit Research Articles

ELDPC: An Efficient LDPC Coding Scheme for Phase-Change Memory

Low read latency, long lifetime, and high storage density have all been demonstrated in phase-change memory (PCM), making it an attractive contender for main memory. However, due to resistance drift per cell caused by long-term storage, data reliability becomes a major challenge. Low-density parity-check (LDPC) codes with improved error correction capability can be used in PCM to reduce bit error rates and thus improve data reliability. More interestingly, when the raw bit error rates (RBER) of various pages in PCM is compared at the same storage time, a considerable gap appears, resulting in high sensing and decoding latency. We propose eLDPC, an efficient LDPC coding scheme for reducing sensing and decoding latency, in this paper. We start with a preliminary experiment, which reveals that there is a significant variation in resistance drifts between adjacent distributions, resulting in a large RBER gap for different pages. Then, using a submatrix of the parity-check matrix to shorten the codeword length, eLDPC is inspired to encode pages with lower RBER. The original bit sequence is separated into even bit sequence (EBS) and odd bit sequence (OBS) for pages with higher RBER. eLDPC is used to encode EBS and OBS independently. By utilizing optimized soft information, EBS and OBS are eLDPC decoded. eLDPC can significantly improve error correction capability of LDPC hard decoding, effectively eliminating soft decoding processes and lowering decoding latency. The results of simulations show that eLDPC can greatly decrease decoding iterations and time.

Two Bars Too Many: “An Odd Bit of History” in the Reception of Beethoven’s Fifth Symphony

Two Bars Too Many: “An Odd Bit of History” in the Reception of Beethoven’s Fifth Symphony

All-Optical Non-Inverted Parity Generator and Checker Based on Semiconductor Optical Amplifiers

An all-optical non-inverted parity generator and checker based on semiconductor optical amplifiers (SOAs) are proposed with four-wave mixing (FWM) and cross-gain modulation (XGM) non-linear effects. A 2-bit parity generator and checker using by exclusive NOR (XNOR) and exclusive OR (XOR) gates are implemented by first SOA and second SOA with 10 Gb/s return-to-zero (RZ) code, respectively. The parity and check bits are provided by adjusting the center wavelength of the tunable optical bandpass filter (TOBPF). A saturable absorber (SA) is used to reduce the negative effect of small signal clock (Clk) probe light to improve extinction ratio (ER) and optical signal-to-noise ratio (OSNR). For Pe and Ce (even parity bit and even check bit) without Clk probe light, ER and OSNR still maintain good performance because of the amplified effect of SOA. For Po (odd parity bit), ER and OSNR are improved to 1 dB difference for the original value. For Co (odd check bit), ER is deteriorated by 4 dB without SA, while OSNR is deteriorated by 12 dB. ER and OSNR are improved by about 2 dB for the original value with the SA. This design has the advantages of simple structure and great integration capability and low cost.

Very Large Scale Integrated-Circuit Architecture for Offset Quadrature Phase Shift Keying Modulation Using Offset Generator

This work presents an architecture for Offset Quadrature Phase Shift Keying (OQPSK) using an Offset generator. The Offset generator generates symbol patterns such that there is a maximum phase shift of ±90° only between the symbols, unlike the Quadrature Phase Shift Keying (QPSK) modulator which has a maximum of ±180° phase shift. Here the effort of designing an Offset generator, which can be embedded onto QPSK modulator to generate OQPSK with minimum combinational logic, has been discussed. Whenever the input symbols to the Offset generator varies in phase with a ±180° in constellation, it generates an intermediate symbol which differs only in ±90° with the previous one. Then it continues to give out the original symbol to be transmitted. This follows the exact OQPSK technology while it doesn't follow the conventional generation method of OQPSK modulation which provides an offset between the even and odd bit patterns of the symbols to be transmitted. The architecture is modelled using Verilog HDL and the functionality is validated from the simulation result.

An Efficient Hardware-Based Fault-Tolerant Method for SMS4

The SMS4 cryptosystem has been used in the Wireless LAN Authentication and Privacy Infrastructure (WAPI) standard for providing data confidentiality in China. So far, reliability has not been considered a primary objective in original version. However, a single fault in the encryption/decryption process can completely change the result of the cryptosystem no matter the natural or malicious injected faults. In this paper, we proposed low-cost structure-independent fault detection scheme for SMS4 cryptosystem which is capable of performing online error detection and can detect a single bit fault or odd multiple bit faults in coverage of 100 percent. Finally, the proposed techniques have been validated on Virtex-7 families FPGA platform to analyze its power consumption, overhead and time delay. It only needs 85 occupied Slices and 8.72mW to run a fault-tolerant scheme of SMS4 cryptosystem with 0.735ns of detection delay. Our new scheme increases in minimum redundancy to enhance cryptosystem’s reliability and achieve a better performance compared with the previous scheme.

Two Novel Blind Equalization Algorithms for Rectangular Quadrature Amplitude Modulation Constellations

Two novel blind equalization techniques for odd bit rectangular quadrature amplitude modulation (RQAM) signaling are proposed in this paper, namely, rectangular contour algorithm (R RECT CA) and improved rectangular contour algorithm (IRCA). The proposed R RECT CA algorithm minimizes the dispersion of constant with respect to a rectangular-shaped zero error contour. The algorithm exploits the geometry of the RQAM to correct phase error within 180°, thus enhancing the convergence rate while minimizing the equalizer mis-adjustments. On the other hand, the proposed IRCA algorithm employs the estimated output from the decision device into the cost function, thus guiding the equalizer output to reside on multiple zero error rectangular shaped moduli. This method of feeding back the slicer output further reduces the mis-adjustment between the transmitted constellation and the new cost function in an efficient manner, which leads to faster convergence and better intersymbol interference suppression. The proposed algorithms can also work for the square QAM by mere change of only two constellation dependent constants, thus facilitating the implementation in hardware to enable transmission of both even and odd number of bits per symbol based constellations. Steady-state error analysis, MSE, and residual ISI comparison through the simulation results confirm the good performance of the proposed algorithms. Furthermore, the convergence characteristics of the proposed IRCA scheme establish the supremacy of IRCA over R RECT CA, which is its parent algorithm.

FPGA IMPLEMENTATION OF 4D-PARITY BASED DATA CODING TECHNIQUE

The scenario of communication systems is changing with the immense development of electronic devices and the increasing demand of data in communication systems. When the communicating data follows the wireless path in its communication channel then the presence of the electromagnetic signals in the communication media can effects the integral value of the signal and may lead to the wrong reception of the data at the receiver side. This wrong reception is further reflected as the wrong processing data to generate the undesired system output. So, the communication systems are required to have some hardware or software resources to detect the effects of the environmental electromagnetic signals, called noise. A number of techniques have been proposed to estimate the effect of noise as well as the actual value of the transmitted data. One of the simplest methods used to identify a change in the transmitted digital data stream is by adding even or odd parity bit with the transmitted data and checking verifying its authenticity at the receiver end after receiving the data. A single bit parity scheme only informs about an odd bit change in the transmitted data. One of the implementation methods of using the similar concept for noise effect identification and correction is by using 4-dimensional parity method. This method involves generation of parity bits of a pre-accumulated data in four directions. Each of the data bit is used to generate 4-parity bits. The involved method can be effectively used to identify and correct 3-bit of error in the transmitted data with the help of the parity bits. In the proposed work the same error detection and correction method is simulated on a field programmable gate array device using Xilinx ISim Tool.

Coarse Network Coding: A Simple Relay Strategy for Two-User Gaussian Interference Channels

Reminiscent of the parity function in network coding for the butterfly network, it is shown that forwarding an even or odd indicator bit for a scalar quantization of a relay observation recovers 1 bit of information at the two destinations in a noiseless interference channel where interference is treated as noise. Inspired by this observation, a scalar quantization-binning strategy for a two-user interference relay channel is proposed where the relay simultaneously helps both users using an out-of-band link of constant rate R0. For the proposed strategy, we devise practical coding schemes using low-density parity-check codes for two scenarios: 1) a matched scenario where the input alphabet of the interference signal is known to the destination decoder, and 2) a mismatched scenario that assumes no such knowledge. In both scenarios, we show that our strategy significantly improves the performance. We also present a theoretical analysis of our coding scheme using generalized mutual information.

Embedded Test Resource for SoC to Reduce Required Tester Channels Based on Advanced Convolutional Codes

Test resources can be embedded on the chip to reduce required external tester channels. In order to obtain the maximal reduction of tester channels, a single-output encoder based on the check matrix of the (n, n-1, m, 3) convolutional code is presented. When the five proposed theorems are satisfied, the encoder can avoid two and any odd erroneous bit cancellations, handle one unknown bit (X-bit), and diagnose one erroneous bit. Two types of encoders are proposed to implement the check matrix of the convolutional code. A large number of X-bits can be tolerated by choosing a proper memory size and weight of the check matrix, which can also be obtained by an optimized input assignment algorithm. In order to get the full diagnostic capability, the proposed encoder can be reconfigured into a simple linear-code-based encoder by adding some additional gates. Experimental results show that the proposed encoder has an acceptable level of X-bits tolerance and a low aliasing probability.

Theory and practice

Theory is usually assumed to precede practice but ‘Practice preceding theory’ is the telling sub-title to Patrick Hodgkinson's essay on Leslie Martin on p. 297 of this issue. It is a full year since we published an extended celebration of Martin's work together with his essay ‘The grid as generator’ (arq 4/4). Kenneth Frampton's subsequent Postscript (arq 5/1) placed Martin in a historical perspective. Spurred by Frampton's assessment, Hodgkinson now reminds us how Martin's later theoretical work can be said to have had its origins in the studio's early work.This thought-provoking reminder comes at a time when, in the UK, architecture's standing as a research-led university discipline remains as low as ever. Once again in the government's recent Research Assessment Exercise no architecture school achieved the highest rating. This was unremarked upon both by the professional press (which was much more interested in the upsets at the top end of the league-table) and by the RIBA (which probably hasn't even noticed and has certainly never grasped the significance of university research). It seems that neither much of the ‘theory’ which so many architecture academics expound nor the odd bit of practice that they manage to undertake is highly rated by the assessors.This, of course, is not the outcome intended by the 1958 Oxford Conference on Architectural Education (master-minded by Martin) which determined that in future all architects should be educated within the research-led university system. But does the RAE debacle matter? It certainly does. Research-rich schools are better resourced — and that benefits both teaching and practice. We need to take a hard look at why architecture fares so badly — and to question its grouping with construction management and surveying. We must also consider the very nature of university-based architectural research. Hodgkinson is right when he concludes, ‘much thought still needs to be given to architectural theory if it is to raise itself from being purely academic — and therefore practically useful.’But take a look, too, at the articles on pp. 305 and 312 of this issue. The first, by occasional practitioner and academic Peter Blundell Jones, sets out the case for ‘Working with the given’. In the second, ‘New meanings from old buildings’, Blundell Jones and another practitioner/academic, John Sergeant, appraise three very modest house conversions and extensions designed by them and by David Lea. These architects have evolved their position over many years — developing, through building, discussion and writing, a genuinely sustainable approach to the use of resources. Their buildings may be modest but, together with their writing, they eloquently encapsulate an approach or theory that is increasingly relevant — and utterly practical.

The Bird, the Cross, and the Emperor: Investigations into the Antiquity of the Cross in Cygnus

When was it that someone first gazed up at the Summer Milky Way and recognized the Cross among the stars of Cygnus? After the Big Dipper and the Seven Sisters of the Pleiades, the Northern Cross is among the most familiar of asterisms, for Westerners at least. Turn to almost any modern handbook on the constellations and we find under Cygnus that the Swan often goes by this well known alias. Little explanation is required; the Cross being simply a matter of common knowledge. But when did it become so? One such popular guide, by the late veteran interpreter of the stars, Julius Staal, ventures only that it was 'early Christians' who recognized the cruciform shape of Cygnus.1 It is certainly a reasonable guess; but, which early Christians recognized the Cross where others in their day would have imagined a great swan flying along the river of milk flowing from Hera's breast? Although it seems little more than an odd bit of trivia, attempting to answer the question of the asterism's antiquity touches on some interesting aspects of our cultural history. I hope to show how light from this admittedly peculiar angle may illuminate ways that astral imagery played upon the early Christian imagination, particularly as related to aspects of the history of Constantine the Great, the first Christian emperor of Rome.

The Yellow Admiral

When last we had news of Captain Jack Aubrey and his close friend and shipmate Dr Stephen Maturin, in the 17th of the series of historical novels by Patrick O'Brian, they had thwarted a French invasion of Ireland. The 18th and latest book in the series, The Yellow Admiral , finds Aubrey at home on dry land but awash in political and family squabbles. In the nick of time he and Maturin receive orders to set sail again. There is not a moment to be lost. In the course of this novel Aubrey battles the French fleet, and Maturin does the odd bit of spying for the admiralty, but the book's main purpose seems to be to set the stage for greater adventures (in better novels) to come. Therefore, I can only recommend this book to diehard fans who fear that some day, by choice or necessity, O'Brian will cease to

Kaymar — Good advice from PERA

“All shop‐floor workers need encouragement to reach full productivity”. That comment from P.A.R. (‘Nobby’) Clark, joint managing director of Kaymar Ltd, summarises the company's philosophy. He's not on his own, Kaymar's customers obviously agree. They have enabled Kaymar to become a £3.0 million turnover company in less than 20 years. “We are all at our place of work more than we are at home. Is it any wonder that ill‐designed industrial furniture causes poor productivity, increased absenteeism, excessive ‘P + T’ time?” asks Mr. Clark. “The odd bit of slotted‐angle and timber thrown together, perhaps painted in garish colours, at the wrong working height in poor light and laughingly called a work bench should be a thing of the past. People are too expensive a resource to be hindered by their environment.”