At the Heart of the Driverless Car - Inside Unmanned Systems


To achieve these numbers, the GNSS system must embed a combination of core GNSS technologies. These include multi-constellation GNSS reception for large numbers of measurements and a multi-band signal reception for minimal convergence time as well as 3D automotive dead reckoning to smooth multipath effects and to maintain positioning in tunnels, parking facilities and other indoor settings. This combination of technologies can cope with the level of interruptions to carrier phase lock and the multipath distortion caused by bridges, signs, trees and buildings in such environments.

Multipath Effects in GPS Receivers: A Primer - Programmer Books


Autonomous vehicles use global navigation satellite systems (GNSS) to provide a position within a few centimeters of truth. Centimeter positioning requires accurate measurement of each satellite's direct path propagation time. A GNSS receiver model is developed and the effects of multipath are investigated. MATLABtm code is provided to enable readers to run simple GNSS receiver simulations. More specifically, GNSS signal models are presented and multipath mitigation techniques are described for various multipath conditions.

Interdependent Gibbs Samplers Machine Learning

Gibbs sampling, as a model learning method, is known to produce the most accurate results available in a variety of domains, and is a de facto standard in these domains. Yet, it is also well known that Gibbs random walks usually have bottlenecks, sometimes termed "local maxima", and thus samplers often return suboptimal solutions. In this paper we introduce a variation of the Gibbs sampler which yields high likelihood solutions significantly more often than the regular Gibbs sampler. Specifically, we show that combining multiple samplers, with certain dependence (coupling) between them, results in higher likelihood solutions. This side-steps the well known issue of identifiability, which has been the obstacle to combining samplers in previous work. We evaluate the approach on a Latent Dirichlet Allocation model, and also on HMM's, where precise computation of likelihoods and comparisons to the standard EM algorithm are possible.

One gigabit 4G: The coming of LTE Advanced


Today, you're doing well if you get 12 Mbps from your 4G LTE connection. For tomorrow, companies such as Ericsson and Qualcomm are working on delivering Gigabit LTE speeds to your smartphones. One carrier, Swisscom, even boasts that it's hit data transfer speeds of 1Gbps on its mobile network. First, LTE Advanced (LTE-A) is not a single technology. It's a mix of three different techniques to deliver not just superior bandwidth but better connections in general at cell edges.

Technical Perspective: Is Your WiFi a Sensor?

Communications of the ACM

Romit Roy Choudhury is a professor and Jerry Sanders III AMD Inc. Scholar in the Department of ECE and CS at the University of Illinois at Urbana-Champaign, IL, USA. To view the accompanying paper, visit