A Worst-Case Analysis of Direct-Sequence Spread-Spectrum in Multipath Channels

We consider a direct-sequence spread-spectrum system operating in an indoors environment in the presence of multiaccess and multipath interference, and additive white Gaussian noise. We focus on the worst-case bit error probability of this system with a constraint on signal-to-interference ratio, and derive a Chernoff-type upper bound on this error probability. We evaluate the upper bound for a special case in order to gain understanding of the basic worst-case performance. We also compare the effects of the worst-case multipath interference with those of the worst-case multiuser interference of equivalent noise power, and observe that the worst-case performance under multipath interference is very similar to and only slightly worse than that under multiuser interference. We find out that the worst-case performance can be very good for a large number of chips per bit, whereas it is very poor for a smaller number of chips per bit, and for non-spread-spectrum systems

A Worst-Case Analysis of Direct-Sequence Spread-Spectrum in Multipath Channels

We consider a direct-sequence spread-spectrum system operating in an indoors environment in the presence of multiaccess and multipath interference, and additive white Gaussian noise. We focus on the worst-case bit error probability of this system with a constraint on signal-to-interference ratio, and derive a Chernoff-type upper bound on this error probability. We evaluate the upper bound for a special case in order to gain understanding of the basic worst-case performance. We also compare the effects of the worst-case multipath interference with those of the worst-case multiuser interference of equivalent noise power, and observe that the worst-case performance under multipath interference is very similar to and only slightly worse than that under multiuser interference. We find out that the worst-case performance can be very good for a large number of chips per bit, whereas it is very poor for a smaller number of chips per bit, and for non-spread-spectrum systems

Sector Promotion in Mexico and the Rol of China in Supply Chains

In this quantitative study a distributed lag model with dichotomous variable in its interactive form is applied and its results prove that the link between Chinese imports and Mexican exports to the United States made by Mexico has remained unchanged from 2001 to 2021 in addition to having a magnitude higher than that registered during the first 7 years of the application of NAFTA At the same time the statistical figures confirm that the participation of the added value of exports in total manufacturing production has sustained constant growth Given recent events such as the trade frictions between the world s two largest economies the emergence of several mega regional trade agreements such as CPTPP RECP and the renewal of NAFTA etc the potential reconfiguration of global value chains and supply could become a major challenge for the sustained development of production plants and the Mexican econom

Producing cluster states in charge qubits and flux qubits

We propose a method to efficiently generate cluster states in charge qubits, both semiconducting and superconducting, as well as flux qubits. We show that highly-entangled cluster states can be realized by a `one-touch' entanglement operation by tuning gate bias voltages for charge qubits. We also investigate the robustness of these cluster states for non-uniform qubits, which are unavoidable in solid-state systems. We find that quantum computation based on cluster states is a promising approach for solid-state qubits.Comment: 4 pages, 1 figure