Performance of feedback and switch space diversity 900 MHz FM mobile radio systems with Rayleigh fading

A theoretical and experimental comparison of performance has been made between two types of predetection switching space diversity mobile radio systems. This comparison was made at a frequency of 840 MHz using simulated Rayleigh fading for a vehicle speed of about 80 mi/h. The switch diversity system was a conventional receiver antenna switching technique with two simulated physically separated receiving antennas and a single transmitting antenna. The feedback diversity system used a single receiving antenna with two simulated physically separated transmitting antennas. The transmitting antennas were switched remotely from the receiver. The difference in the performance of the two systems was shown to be primarily due to time delay inherent in the remote antenna switching technique.     

Signal-detection and signal-processing algorithms for code-division multiple-access satellite mobile communications systems employed simultaneously with satellite radio navigation systems

The Markovian theory of random process estimation is applied to synthesize optimal (and close to optimal) algorithms with discrete-parameter feedbacks. The problem is solved in the case when it is necessary to provide for detection and complex nonlinear processing of discrete-continuous noiselike signals used in code-division multiple-access satellite mobile communications systems employed simultaneously with satellite radio navigation systems. It is assumed that the discrete part of a discrete-continuous state vector to be estimated contains two components, each being characterized by a multiposition simple Markovian chain and that desired signals are observed in the presence of additive partially colored (correlated) Gaussian noises.     

Theoretical and experimental investigation of feedforward signal regeneration as a means of combating multipath propagation effects in pilot-based SSB mobile radio systems

A technique is described, feedforward signal regeneration (FFSR), to combat the effects of multipath propagation on VHF and UHF pilot tone single sideband (SSB) mobile radio systems. Unlike feedforward automatic gain control (FFAGC), FFSR suppresses both the random amplitude and phase fluctuations in the received signal. Extensive laboratory and field tests have shown that the operation of SSB at UHF frequencies is a viable proposition for both speech and data communication.     

OFDM for data communication over mobile radio FM channels. I.Analysis and experimental results

The performance of OFDM/FM modulation for digital communication over Rayleigh-fading mobile radio channels is described. The use of orthogonal frequency division multiplexing (OFDM) over mobile radio channels was proposed by Cimini (1985). OFDM transmits blocks of bits in parallel and reduces the bit error rate (BER) by averaging the effects of fading over the bits in the block. OFDM/FM is a modulation technique in which the OFDM baseband signal is used to modulate an FM transmitter. OFDM/FM can be implemented simply and inexpensively by retrofitting existing FM communication systems. Expressions are derived for the BER and word error rate (WER) within a block when each subchannel is QAM-modulated. Several numerical methods are developed to evaluate the overall BER and WER. An experimental OFDM/FM system was implemented and tested using unmodified VHF FM radio equipment and a fading channel simulator. The BER and WER results obtained from the hardware measurements agree closely with the numerical results     

Network and single user performance evaluation of a mobile data system over flat fading transmission channels

In this paper the contrasting effects of transmission impairments and capture on both the network and single user performance of a slotted Aloha system are investigated in a mobile radio environment, accounting for frequency non-selective random propagation phenomena, and employing the packet error probability in order to define packet losses and capture. With this study we demonstrate that it is possible to generalize in a real propagation context a method previously proposed in literature for evaluating the network behavior in terms of steady-state throughput, backlog and stability in conventional transmission conditions, i.e., when all the transmission channels were error-free and the collisions caused the loss of all the packets involved. Moreover, we indicate under which specific constraints on the terminal mobility we can apply this method to analytically predict the single user performance, which we show being an important design parameter. Through the numerical results reported we quantitatively point out that in the absence of coding capture increases system stability and moderately improves the overall system throughput and backlog. We also outline the trade-off between an increased capture gain obtained by means of coding and the corresponding system cost in terms of complexity and bandwidth occupancy. Furthermore, we demonstrate the unfairness which affects the single user performance and the consequent need for countermeasures in order not to discriminate among users differently located within the network; yet, this last solution is detrimental as regards the positive capture effects.This work was supported by M.U.R.S.T. and C.N.R. (Italy).     

120 Mbit/S QPSK data and multi-channel TV transmission over 13 kmfibre to a 60 GHz mobile radio link using an electroabsorption modulatoras a transceiver

A broadband analogue fibre-radio millimetre-wave system has been constructed. The system is capable of downstream 120 Mbit/s QPSK data transmission over 13 km of fibre and onward radio transmission at 60 GHz. Simultaneous transmission of downstream data, broadcast video and upstream data over fibre is also incorporated using sub-carrier multiplexing     

Integration of millimeter-wave and optical link for duplex transmission of hierarchically modulated signal over a single carrier and fiber for future 5G communication systems

Telecommunication Systems - Integration of optical and millimeter-wave systems provide a promising solution for future giga-bits per second wireless communication systems. We have proposed and...