Mickael D. Batariere

An experimental OFDM system for broadband mobile communications

We present an overview of an experimental 20 MHz 2/spl times/2 MIMO-OFDM system for operation at 3.65 GHz. The transmitted signal characteristics, data collection setup, measurement analysis, and timing acquisition algorithms are described. Field trials from a base station with two transmit antennas to a two-antenna mobile receiver are planned in a coverage area having a two mile radius. The first phase of the development process of this experimental system is complete, and initial laboratory results in the area of MIMO channel estimation and demodulation are presented for an indoor pedestrian MIMO channel.

Wideband MIMO mobile impulse response measurements at 3.7 GHz

This paper summarizes the propagation characteristics of a 20 MHz channel at a carrier frequency of 3.676 GHz transmitted from a two-antenna base to a two-antenna mobile receiver. The experiments were conducted in a moderate density suburban setting outside Chicago, Illinois. The transmit and receive systems are described, as are the data collection procedures and data analysis. The results include path loss measurements and various metrics of the MIMO channel, such as channel impulse responses, rms delay spread, and other spatial characteristics.

Data fusion based on neural network for the mobile subscriber location

The position estimation of a cellular mobile subscriber is a requirement driven by emergency calls, and also by the emergence of new location based services. In order to reach a better accuracy than the one provided by each base station separately, one approach is to fuse the measurements of several base stations like the direction of arrival, the time of arrival,... This paper presents the application of an artificial neural network to fuse radiolocation measurements and confidence of measurements. Based on radiolocation data provided by a CDMA simulator an accuracy of 65 m in 67% of cases has been reached. In order to avoid the use of a neural network fuser specifically dedicated to a cell, it is necessary to generalize the training process. It allows to localize the mobile station in any circumstances. This process allows to have a low cost fuser compatible with FCC requirements.

Seasonal variations in path loss in the 3.7 GHz band

This work presents path loss measurements through a 20 MHz wireless channel at a carrier frequency of 3.676 GHz in a suburban setting outside Chicago, Illinois. The data collection system is described and the measurement environment is characterized. Results are presented for two seasons, winter and summer, demonstrating that tree foliage creates an average excess path loss of between 3 and 7 dB.

Low-complexity technique to increase capacity of mobile broadband systems

The paper describes a low-complexity technique to increase the capacity and performance of mobile broadband systems, particularly for fast changing, highly frequency selective channels. The technique is very low complexity and can be implemented with todays hardware at low cost. It entails minor scheduling constraints and pilot-plus-data aided channel estimation for coherent demodulation with a reduced number of pilot tones. Simulation results show a 15% spectrum efficiency improvement in the context of a high-mobility orthogonal frequency division multiplexing (OFDM) wireless communication system such as 802.20 or 4G.