Sumit Jamuar: Indians are 20 of the world's population, but represent only 1 of existing genetic data

As the new frontier in medicine, genomics brings with it the hope of allowing researchers to find the cure for a number of largely incurable diseases, from cancer to Alzheimer’s, to infectious diseases and beyond. The challenge now is to map the DNA of as many ethnicities and nationalities as possible. Currently, 81 per cent of the existing genetic data is from Caucasians. One company is trying to bridge the gap by analysing the genome of different ethnicities in India, with hopes of expanding to the rest of Asia, Latin America and Africa. “You look at India, with 1.3 billion people, 20 per cent of the world’s population. A lot of people of Indian ethnicities reside globally, and yet they comprise less than 1 per cent of genomic insights and understanding”, says Sumit Jamuar, chairman and CEO of Global Gene Corp. He spoke with LSE Business Review’s managing editor, Helena Vieira, on 9 November 2017, during Web Summit in Lisbon

Adaptive spatial mode of space-time and spacefrequency OFDM system over fading channels

In this paper we present a 2 transmit 1 receive (1 Tx : 1 Rx) adaptive spatial mode (ASM) of space-time (ST) and space-frequency (SF) orthogonal frequency division multiplexing (OFDM). At low signal to noise ratio (SNR) we employ ST-OFDM and switch to SF-OFDM at a certain SNR threshold. We determine this threshold from the intersection of individual performance curves. Results show a gain of 9 dB (at a bit error rate of 10-3) is achieved by employing adaptive spatial mode compared to a fixed ST-OFDM, almost 6 dB to fixed SF-OFDM, 4 dB to Coded ST-OFDM and 2 dB to a fixed coded SF-OFDM, at a delay spread of 700 ns

A low power 2.4 GHz variable-gain low noise amplifier for wireless applications

A 2.4 GHz variable-gain low noise amplifier (VGLNA) intended for use in a Wide-band Code Division Multiple Access receiver was designed in 0.18 um CMOS process for low voltage and low power applications. Rivaling classical designs using voltage mode approach, this design used the current mode approach, utilizing the current mirror principle to obtain a controllable gain range from 8.26 dB to 16.95 dB with good input and output return losses. By varying the current through the widths of transistors and a bias resistor, the VGLNA was capable of exhibiting 8 dB gain tuning range without degrading the noise figure. Therefore, higher gain was possible at lower current and thus at lower power consumption. Total power consumption simulated was 4.63 mW from a 1 V supply and this gave a gain/power quotient of 3.66 dB/mW. Comparing this with available published data, it was observed that this work demonstrated a good gain tuning range and the lowest noise figure with such power consumption

An improved power consumption circuit of a 5.7 GHz variable-gain low noise amplifier (VGLNA) for RF applications

A low voltage topology that uses a capacitively coupled resonating element has been introduced using 0.18 mum CMOS technology. The topology utilizes the decoupling scheme to dc isolate circuit elements that are connected in series and share a common dc current. A 5.7 GHz variable-gain low noise amplifier (VGLNA) is presented with simulation results exhibiting a noise figure of 1.02 dB, power gain of 19.41 dB with gain tuning range of 6 dB and IIP3 of -1.11 dBm. The power consumption reported is 12.88 mW at supply of Vdd = 0.7 V for power optimization circuit. Simulation results show that the proposed VGLNA has better noise performance and improved power consumption compared to the conventional cascode VGLNA

A novel ternary CDMA code for TPSK modulation scheme

In code division multiple access (CDMA), two or more chips are grouped together to form symbols and each symbol is transmitted during the symbol period. The phase shift keying (PSK) modulation techniques map the digital baseband data into two or more possible signals by varying the phase of a radio frequency (RF) carrier. The recently proposed PSK scheme called ternary PSK (TPSK) scheme can convey three possible symbols. In this paper, a novel ternary based CDMA sequence so-called large area synchronous even ternary (LAS-ET) sequence is introduced to increase spectrum efficiency in TPSK scheme. Its sequence duty ratio and cross-correlation are analyzed. The performance analysis of this sequence is compared with the large area synchronous (LAS) sequence in term of symbol error rate and chip error rate (CER) over various channel models. It is shown that TPSK scheme in LAS-ET sequence outperforms LAS sequence in terms of CER evaluation. At the same time, the spectrum efficiency is doubled when a pair of chips in LAS-ET sequence is mapped into one symbol

A simplified sphere decoding algorithm for MIMO transmission system

In sphere decoding the choice of sphere radius is crucial to excellent performance. In Chan-Lee sphere decoding -based algorithm, the problem of choosing initial radius has been solved by making the radius sufficiently large, thus increasing the size of the search region. In this paper we present maximum likelihood decoding using simplified sphere decoder as apposed to the original sphere decoder for the detection of cubic structure quadrature amplitude modulation symbols. This simple algorithm based on Chan-Lee sphere decoder allows the search for closest lattice point in a reduced complexity manner compared to original sphere decoder for multiple input multiple output system with perfect channel state information at the receiver. Results show symbol error rate has stabilized even at very low initial value of the square radius

A full rate concatenated space-frequency and space-time OFDM over Naftali fading channels

In this paper we investigate 2 transmit and 1 receive (2Tx:1Rx) space-frequency orthogonal frequency division multiplexing (SF-OFDM) and space-time OFDM (ST-OFDM) concatenated with convolutional channel coding as a redundancy method to combat channel impairments. We built our SF and ST-OFDM on top of our coded OFDM (COFDM) with coding rate of 1/4 and constraint length of 10. We simulate our concatenated SF-OFDM and ST-OFDM over a multipath fading channel using Naftali 802.11 channel model under different delay spreads in relation to outdoor environment. Concatenated SF- OFDM performs slightly better than ST-OFDM at delay spread of 2.0 microseconds, but both are almost comparable at all other delay spreads. These two schemes outperforms other schemes such as single antenna coded OFDM and Alamouti's Space-Time Block Code (STBC) under these conditions by as much as 10 dB at BER of 104

Analysis of transmit-receive diversity in Rayleigh fading

We analyze the error performance of a wireless communication system employing transmit-receive diversity in Rayleigh fading. By focusing on the complex Gaussian statistics of the independent and identically distributed entries of the channel matrix, we derive a formula for the characteristic function (c.f.) of the maximum output signal-to-noise ratio. We use this c.f. to obtain a closed-form expression of the symbol error probability (SEP) for coherent binary keying. The method is easily extended to obtain the SEP for the coherent reception of M-ary modulation schemes

TCP throughput optimization over 802.11 MAC protocol in multi-hop ad-hoc networks.

The acknowledgment strategy has great potential to increase the TCP throughput when it runs over 802.11 MAC protocol. In particular TCP acknowledgments carry out an extensive number of medium accesses as they compete in the same route as data packets for media. As the load increases, the well-known hidden terminal effects caused by interference between ACK and data packets in MAC layer can degrade TCP performance dramatically if TCP acknowledges every incoming data packets. In this paper, we propose a TCP-MAC interaction strategy which tries to reduce the number of induced ACKs by monitoring the channel condition. To this end, the total collision probability collected along the path in MAC layer is used to properly set the number of the delayed ACKs in TCP. Based on the measured collision probability, TCP sender dynamically adjusts itself to the channel condition by delaying less ACKs in high traffics and more in low traffic conditions. The simulation results show a reasonable tradeoff between performance under moderate and high traffics

A study of antenna array based multipath propagation phenomenon in LAS-CDMA standard

Throughout the history of wireless communications, spatially diversity's antenna array system has being important in improving the radio link between wireless users. Moreover, this system are proposed to reduce the multipath fading through its directivity narrowly radiation beam. The introduction of interference free window in delay domain from newly LAS-CDMA standard has received many attentions for furthering research on multipath delay spread. In this paper, we studied the effect of angular spread on maximum excess delay in multipath propagation environments. Then, we examined the application of antenna array in LAS-CDMA standard to overcome this multipath phenomenon. First of all, the multipath propagation literatures are reviewed, followed by the explanation of maximum angular spread in a simple discrete ring of scatterers model. Comparison analyses are made between conventional omnidirectional antenna and narrow beam antenna array. Finally, the analytical performances in term of power delay profile are presented