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Aaltonen L.,VTT Technical Research Center of Finland | Kalanti A.,Aalto University | Pulkkinen M.,Aalto University | Paavola M.,Mobile Europe | And 2 more authors.
IEEE Journal of Solid-State Circuits | Year: 2011

The interface for a capacitive 2-axis micro-gyroscope is implemented in a 0.35-μm HVCMOS technology with a total area of 4.3 mm;2. The ASIC comprises the complete analog interface electronics for the gyroscope, while the focus of the design is in maintaining low supply current and in reducing the chip area. The paper reports the design of reference circuits, high-voltage generation, drive-loop and the capacitive open-loop readout circuits. The prototype sensor that is measured is assembled by directly wire-bonding the stacked dies comprising the interface electronics and the sensor element. The noise floors of the two sensors are 0.028°/s/√Hz for z-axis and 0.032°/s/√Hz for y-axis. The supply current of the chip is 2.2 mA from a 3 V-supply. © 2011 IEEE. Source

Frantti T.,Mobile Europe
Expert Systems with Applications | Year: 2012

This paper considers an embedded fuzzy expert system for non-feedback uplink power control of wireless local area networks (WLANs). The main idea is to minimize the transmission power of the nodes while keeping the transmission errors at an acceptable level. In the developed method, receivers collect signal strength values which are used by the control systems to define an acceptable transmission power level. The functionality of the proposed solution is demonstrated with simulations, which prove that the use of the expert system to open-loop systems can significantly decrease transmission power, increase energy efficiency and decrease interference to adjacent access points and associated nodes. © 2012 Elsevier Ltd. All rights reserved. Source

Pantelidou A.,Mobile Europe | Ephremides A.,University of Maryland University College
IEEE Transactions on Information Theory | Year: 2011

The problem of optimal scheduling of multicast traffic in time-varying wireless networks is studied in the framework of utility maximization. Since the wireless channel cannot be known exactly, only scheduling policies that take decisions based on a possibly inaccurate estimate of the wireless channel state are considered. A stationary, on-line, gradient-based scheduling and rate control policy is introduced which identifies at every decision instant the sources that should access the wireless medium along with their respective transmission rates. Furthermore, in the case that more than one optimal rate allocation is possible, the one that requires the minimum sum-power expenditure is selected by the policy. The optimality of the proposed policy among all policies that have access to the same estimate of the current wireless channel state is established through stochastic approximation arguments. © 2011 IEEE. Source

Myllyla M.,Mobile Europe
Conference Record - Asilomar Conference on Signals, Systems and Computers | Year: 2011

A list sphere detector (LSD) is a soft-output enhancement of a sphere detector (SD) that can be used to approximate the optimal MAP detector in the detection of the multiple-input multiple-output (MIMO) signals. The LSDs are based on tree search algorithms and they can be divided into three categories: the breadth-first (BF) search, the depth-first search (DF), and the metric-first (MF) search algorithms. A fair comparison of the feasibility of different search algorithms for MIMO detection requires efficient architecture designs and hardware implementations of the algorithms. In this paper, we compare and analyze the error rate performance, ASIC implementation complexity and detection rate of LSDs based on all three types of search strategies for 4 x 4 MIMO-OFDM systems with 16- and 64-QAM. © 2011 IEEE. Source

Charbit G.,Mobile Europe
IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC | Year: 2012

In this paper, we present a new vehicular paging procedure for fast selection of vehicular relay node cells on access link to connect seamlessly vehicles equipped with an Long Term Evolution (LTE) communication module to the infrastructure. The proposed Radio Resource Control (RRC) protocols allows fast radio bearer setup in the Vehicular User Equipment (V-UE) without need to re-establish the Access-Stratum (AS) level security context stored in the donor evolved Node B (eNB) when selecting a Vehicular Relay Node (V-RN) cell within the donor eNB cell coverage on backhaul link in LTE system. The RRC configuration parameters required for the connection to the vehicular relay node cell takes into account the deterministic movements of the V-UEs within a vehicular target area. © 2012 IEEE. Source

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