Leo Strawczynski

Electronic precompensation of optical nonlinearity

We introduce digital precompensation for optical nonlinearities. A 10-Gb/s transmitter subsystem is described. Experimental results, across 320 and 1280 km of standard single-mode fiber (G.652) without any optical compensators, show substantial elimination of self-phase modulation. Some of the limits of this method are explored.

Electrical domain compensation of optical dispersion [optical fibre communication applications]

Recent advances in the electrical equalization of optical systems are presented in the context of standard methods. We report 10 Gb/s transmission over 60,000 ps/nm of optical dispersion from 3840 km of NDSF (non-dispersion shifted fibre).

Simple equalization scheme for high rate FSK data transmission in the millimeter wave frequency band

In a typical indoor channel, the channel dispersion varies from 10 ns to 100 ns depending on the physical dimensions of the building, the material of the walls etc. Therefore, for high rate data transmission around 160 Mbps, the signals experience severe intersymbol interference (ISI). A simple channel equalization strategy is described for data transmission at around 160 Mbps in the millimeter wave frequency band. CPFSK, a constant envelope modulation, is selected as the modulation scheme. The proposed receivers consist of a noncoherent demodulator followed by a nonlinear equalizer. Performance results of the proposed systems are presented for a two path quasi-static channel.

Delayed diversity transmission for indoor wireless applications

Antenna diversity transmission methods are used to improve the performance of wireless systems. Delayed diversity transmission (DDT) is an attractive option when the main issue is complexity versus performance. The paper discusses the application of delayed diversity transmission to indoor wireless systems in order to reduce the implementation complexity of both base stations and portable terminals. System configurations are suggested that improve the system performance in both the forward and reverse direction. Through computer simulations, the optimum delay, which is the key parameter for the system performance, is derived for an arbitrary frame format. Subsequently, the system performance is tested for the IS-54 standard format structure. DDT shows promise in the reduction of both the power consumption and implementation costs of indoor wireless systems.

Diversity transmission and adaptive MLSE for digital cellular radio

Adaptive equalization at the mobile in conjunction with diversity transmission at the base station can combat the adverse effects of both frequency selective and frequency non-selective fading at the mobile receiver. This is suggested as an alternative to diversity combining at the mobile. Thus a substantial saving in the mobile receivers implementation cost and power consumption is expected. A North American digital cellular radio standard TDMA system with two transmitting antennas at the base station and MLSE at the mobile is considered. System performance results in the presence of severe Doppler frequency shifts and additive white Gaussian noise in a flat fading channel are presented.