A design concept to support both the initial planning and the management of land mobile radio networks with slow frequency-hopping signaling is proposed. It is applicable to the networks with advanced architecture of which the Pan European networks may be an example. The design consists of two planning processes: spatial and frequency planning. A novel heuristic is used to optimize the base station locations with respect to the total interference-to-signal ratio in a network. This ensures economic coverage of the network service area as well as efficient frequency reuse. A repeated application of the same heuristic to the currently measured and/or predicted data offers powerful means to manage a network in order to keep its resources highly available to their users, as is shown in a simulation example which includes not only sources of unintentional (cochannel, adjacent channel, and intermodulation) interference but also sources of intentional (jammer) interference.>

A direct-sequence spread-spectrum (DSSS) receiver using both decision feedback (DFB) and two-sided transversal filters for combatting narrowband interference (NBI) is proposed. The receiver is made up of two branches. In the first branch, the conventional demodulator is followed by a DFB filter, while in the second, auxiliary branch, a demodulator with the carrier in quadrature is followed by a two-sided adaptive transversal (AT) filter. Performance of this receiver was analyzed on the basis of the calculated mean-square error and the probability of error at the output of the receiver. Special attention was paid to the effects caused by the propagation of errors in the DFB filter. The results obtained show that NBI rejection is fairly high and practically does not depend upon the difference of frequencies of the desired and interfering carriers or upon the interfering carrier level.>

A new proposed robust FM demodulator (RFMD) is a simplified version of the recently reported demodulator (FMD) [1] which improves FM system interference immunity. The RFMD is applied to combat the adjacent channel interference and its improvement factor is only negligibly smaller than that of the FMD.

As a result of investigation of interference into FM systems, a new algorithm for the process of demodulation is proposed. When compared to the method using the conventional limiter-discriminator, it offers better immunity against the baseband interference noise. Desired signal processing is performed by the functional devices added to the conventional limiter-discriminator in such a way that this new demodulator can be optimized in the sense of the minimum baseband interference noise. The statistics of the wanted and interfering signals must be known. Several examples involving interference problems in FDM-FM radio-relay systems carrying multichannel telephone signals are elaborated to illustrate the performances of the proposed demodulator. FDM-FM, PSK, or FSK systems are considered the cause of the interference. The noise power ratio (NPR) at the output of the conventional limiter-discriminator and the improvement factor offered by the new demodulator, obtained on digital computer, are presented versus baseband frequency in the form of diagrams. Different IF filters in FDM-FM receiver and transmit filters in the interfering systems are taken into account. The improvement offered by the proposed demodulator is of such a degree that some of the important restrictions in planning different radio systems could be relaxed.