This made it very dif ficult to draw any conclusions as shown in Figure In t his thesis the propagation characteristics of the wireless channel in the 2. The Radio Frequency Identification RFID System, a wireless communication system, applied to vehicular control, is a typical point to point communication system, which one, the radio link formed between the reader, working at the same time as base station and as an end user site, and the tag, the intermediate site, is exposed to electromagnetic disturbances, due reflections off objects in the environment.
For each measurement point, this provides a strength measurement of the signal generated by each cell. Moreover, the predicted power is obtained for the centriod of the coverage zone.
This appro ach generates shadow effects variations that de-correlate exponentially with distance, but cauti on must be taken since it has been shown through extreme value analysis that log-normal shad ows cannot de-correlate exponentially with distance by references in .
In any case, the identity of a base station would need to be ascertained before its signal can be used for position determination.
Propagation delays may also be predicted and used for transmitter identification. Buildings, hills, mountains, foliage, and other physical objects cause the transmitted signal strength to vary over the region covered by a cell. Sites Q, R, and S shows a much higher error rate than the others.
Background It is often desirable, and sometimes necessary, to know the position of a wireless user. This is determined from the measured value of the received signal code power RSCP and the received signal strength available from received signal strength indicator RSSI.
Since the path loss in decibels is assumed to be a random variable with a normal distribution as shown in Equation 32so is the R SS.
The accuracy of ray tracing in predicting signal st rength has been increased by the growth in computational capabilities and database storage. This can be used in cellular networks as a first guess.
The measured length of a mobile radio signal necessary to obtain the local mean of the path loss power has been determined to be in th e range of 20 to 40 wavelengths.
A length of 40 wavelengths was used to obtain the local mean as su ggested in .
Th e spatial correlation properties of the normalized RSS were exploited in detail using conce ntric zones. This procedure includ ed a complete log of all information pertaining to site location and equipment type.
Also, in the optimization phase measured data collected from the live network may b e used to tune the propagation models utilized in the design phase. PAGE 50 41 Figure. TREE LOSSES - SUMMARY For short paths through trees, excess path loss due to trees are on the order of dB/m for GHz and dB/m for 5 GHz depending on tree species.
Hata’s model was based on Okumura’s free test results and predicted various equations for path loss with different types of clutter.
It does not consider the effect of reflection and shadowing. A model that is widely used for predicting path loss in mobile wireless system is the COST Hata model .
The cost Hata model is designed to be used in the frequency band from MHz to.
where L represents the path loss value at a given distance, L0 is a median path loss at 1 km distance, γ is the slope of the path loss curve and F 0 is the adjustment factor comprised of several factors, F 0 = F 1 F 2 F 3 F 4 F 5 which have been explained in the original Lee papers.
Scatter plot of the experimental data on path loss verses distance reveals a third order polynomial trend in the experimental data. Therefore the cubic regression model was fitted using method of least squares which estimates the parameters by minimizing sum of squares of the white noise.
CostHata model was used as reference model for pathloss calculation of field data, this was further adjusted to develop optimized models for path loss prediction in the environments of study, which shows results within 6dB acceptable range, hence recommended for modelling in these environs and other similar GSM environments.Path loss determination using hata model