A comparison of prediction methods for 800 MHz mobile radio propagation

The design and installation of a mobile radio system involves the evaluation or prediction of the propagation characteristics associated with the geographical area of interest. A wide variety of prediction techniques has been developed for different mobile environments, so that the task of selecting an appropriate propagation prediction method can be difficult and complex. This is especially true for systems operating in the upper-UHF band of 800-950 MHz, where mobile radio services are rapidly growing. A practical comparison is given of current prediction techniques available in the literature (for slow lognormal fading rather than multipath Rayleigh fading), with an emphasis on three essential criteria to consider in the selection process: the type of terrain or geography covered by each method, the form of prediction provided (e.g., transmission loss estimates, field strength contour maps, etc.), and the implementation difficulty and degree of sophistication.     

Urban mobile radio propagation at 900 MHz

A series of field trials in London and Birmingham have been used to provide a propagation data base in urban areas at 900 MHz. Measured signal strengths are highly correlated with the results of earlier trials at lower frequencies. The excess loss over plane earth predictions varies with location but is generally in excess of 40 dB.     

Assessment of GTD for mobile radio propagation prediction

The applicability of a GTD-based technique for path loss prediction in cellular radio systems is investigated. The bounds of applicability reported show that such a model could find application in cellular systems with small urban cells and in microcellular systems.<>     

800 MHz v.c.o. for land mobile radio synthesisers

A compact voltage-controlled oscillator, covering 1000 channels with a single range, has been designed and fabricated using GaAs varactor diodes. A c.n.r. of more than 76 dB with 25 kHz offset from carrier and an s.n.r.of more than 52 dB are obtained. Their performance characteristics are described.     

900 MHz land mobile radio improved using circular polarization

Land mobile systems currently use vertically polarized antennas while trying to solve the problem of small sector signal variations, which are greater for vertical polarization than for either horizontal or circular polarization. This difference in small sector variations is shown from results of tests at 430 MHz. The variations at 900 MHz should be more rapid and have amplitudes at least as great as those shown for 450 MHz. At 900 MHz antennas can be made small for mobile service and the improvements noted here may spur developments in circularly polarized antennas.     

Median signal strength prediction for mobile radio propagation in london

Field trials have confirmed that propagation is characterised by a fourth-power law relating median transmission loss to range. Excess losses due to buildings are about 29 dB at 168 MHz and 37 dB at 445 MHz. These values are greater than those measured in smaller cities, but similar to earlier measurements in New York.     

Environment-adaptation mobile radio propagation prediction usingradial basis function neural networks

This paper investigates the application of a radial basis function (RBF) neural network to the prediction of field strength based on topographical and morphographical data. The RBF neural network is a two-layer localized receptive field network whose output nodes from a combination of radial activation functions computed by the hidden layer nodes. Appropriate centers and connection weights in the RBF network lead to a network that is capable of forming the best approximation to any continuous nonlinear mapping up to an arbitrary resolution. Such an approximation introduces best nonlinear approximation capability into the prediction model in order to accurately predict propagation loss over an arbitrary environment based on adaptive learning from measurement data. The adaptive learning employs hybrid competitive and recursive least squares algorithms. The unsupervised competitive algorithm adjusts the centers while the recursive least squares (RLS) algorithm estimates the connection weights. Because these two learning rules are both linear, rapid convergence is guaranteed. This hybrid algorithm significantly enhances the real-time or adaptive capability of the RBF-based prediction model. The applications to Okumura's (1968) data are included to demonstrate the effectiveness of the RBF neural network approach     

Some characteristics of mobile radio propagation at 836 MHz in the Philadelphia area

Mobile radio propagation tests were carried out at 836 MHz from a base station in downtown Philadelphia, Pa., to a mobile which traveled on the city streets. It was found that the median signal power tends to fall off as R^-3for distances greater than 1 to 2 mi from the base station antenna. The mean received-signal level was found to be approximately log-normally distributed with a standard deviation varying from 5 to 10 dB, where the higher values were observed close to the base station.     

910 MHz urban mobile radio propagation: Multipath characteristics in New York city

Small scale statistics of multipath propagation in a heavily built-up urban mobile radio environment are presented. The statistics cover vehicle travel distances on the order of 30 m along streets. Measuring equipment time delay resolution is about 0.1 µs. In some locations, paths with significant amplitudes are observed with excess delays of 9 to 10 µs. The delay spreads (√second central moment of power delay profile) in this environment are on the order of 2 µs. Often the signal at fixed delays has a Rayleigh-distributed amplitude but large departures from the Rayleigh distribution also occur. From the measurements it appears reasonable to model the urban mobile radio channel as a Gaussian quasi-wide-sense stationary uncorrelated scattering channel within a bandwidth of 10 MHz and for intervals along the street of up to 30 m.     

Time-delay/Doppler scattering function for suburban mobile radio propagation at 436 MHz

Time-delay/Doppler scattering functions are presented for two different suburban locations where multipath propagation is evident. The major features of the scattering functions are explained in terms of the surrounding environment and the street orientation with respect to the transmitter.     

Mobile radio propagation in Auckland at 851 MHz

A series of field trials undertaken in Auckland at 851 MHz have shown that the median propagation loss may be estimated by the plane earth propagation loss plus a clutter factor of 45.1, 27.0, 21.7 and 18.3 dB for urban, light urban, suburban and rural environments, respectively.     

Mobile radio propagation in Auckland at 465 MHz

A series of field trials in Auckland at 465 MHz have confirmed that propagation path loss may be characterised by a fourth-power-law distance dependency. The excess loss over plane earth predictions has been measured as 37.8, 26.4, 18.6 and 14.1 dB for urban, light urban, suburban and rural environments, respectively.     

Mobile radio propagation in Auckland at 76 MHz

A series of field trials in Auckland at 76 MHz have confirmed that propagation path loss is normally distributed and may be characterised by a fourth-power-law distance dependency. The path loss standard deviation has been found to be dependent on the mobile terminal's environment and on frequency, but is essentially independent of base station antenna height and path length. The excess path loss over plane earth predictions and the standard deviation of path loss have been measured as 14.6, 5.0, 0.8 and 1.0 dB and 6.2, 5.2, 3.7 and 5.0 dB for urban, light urban, suburban and rural environments, respectively.     

Mobile radio propagation in Auckland at 927 MHz

Field trials in Auckland have shown that in the region 800 m to 5 km from a 50 m elevated base-station propagation loss may be characterised by a fourth-power law distance dependency and may be modelled as plane earth propagation loss plus excess loss of 45.6 dB. In the region closer to the base station, the propagation loss has a different characteristic. A `piecewise? model is proposed.     

User density for 800 MHz microwave mobile radiotelephone communications

The results of a user-density analysis for different systems using the 800 MHz frequency band for mobile radiotelephone communications are presented. Our theoretical investigations show that digital phase-shift keying (p.s.k.), double-binary modulation and analogue s.s.b. systems outperform analogue f.m. systems by a factor of approximately two when compared on a user-density basis.     

Closed-form expressions for the prediction of microcellular mobile radio propagation in urban environments

The paper derives two closed-form expressions for predicting microcellular mobile radio signal levels in urban street-grid environments. The results demonstrate that the two expressions are faster and more accurate than existing models and methods. Benefiting from physical optics and the conservation of energy, the two expressions are alternatives to available techniques such as ray tracing. The dielectric property (i.e., permittivity) of street buildings and other obstacles is essential to the ray tracing technique. However, there are no established, widely accepted techniques for selecting the permittivity in urban mobile environments, which varies in a wide range. Establishing a natural link between the received power after a street corner to the width of the street and the angle of incidence, our expressions show the possibility of making fast and accurate propagation predictions without having to use the permittivity.     

A measured delay-Doppler scattering function for multipath propagation at 910 MHz in an urban mobile radio environment

A delay-Doppler scattering function is presented for multipath propagation at 910 MHz from a vertical antenna 120 m above a street to a mobile vehicle on another street. The direct path between the transmitting antenna and the mobile vehicle was blocked by many tall (over 100 m) buildings. Major features of the scattering function correspond to gross features of the area.