A Low-complexity Successive Detection Method for OFDM Systems over Doubly Selective Channels

For OFDM systems, the time variation of a multipath channel results in inter-carrier interference (ICI). It leads to performance degradations. In reducing the problem, current successive detection methods cost very high computationalcomplexities. Among them, the minimum-mean squareerror successive detection (MMSE-SD) method has the best performance. This work proposes an improved data detection method with low complexity by integrating the techniques of Newton’s iterative matrix inversion method and the MMSE-SD method which considers the effects of signal-to-interference-plusnoise ratio (SINR). In order to efficiently integrate Newton’s and MMSE-SD method, we develop an effective scheme with low complexity for generating the initial values required by Newton’s method. Based on the new initial value scheme, we are able tosimplify the criterion of maximum SINR determination to an equivalent one with lower complexity. As a result, the proposed algorithm has a much lower complexity of O(N2) than O(N3) of the MMSE-SD algorithm, where N is the number of subcarriers. Moreover, simulation results in different channel conditions show that performances of the proposed MMSE-SD method are very close to the MMSE-SD method

A 128-point Multi-Path SC FFT Architecture

This paper presents a new radix-2^k multi-path FFT architecture, named MSC FFT, which is based on a single-path radix-2 serial commutator (SC) FFT architecture. The proposed multi-path architecture has a very high hardware utilization that results in a small chip area, while providing high throughput. In addition, the adoption of radix-2^k FFT algorithms allows for simplifying the rotators even further. It is achieved by optimizing the structure of the processing element (PE). The implemented architecture is a 128-point 4-parallel multi-path SC FFT using 90 nm process. Its area and power consumption at 250 MHz are only 0.167 mm2 and 14.81 mW, respectively. Compared with existing works, the proposed design reduces significantly the chip rea and the power consumption, while providing high throughput.Comment: Conference paper, ISCAS 2020, 5 page

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements