Doppler Shift Effect at The Communication Systems with 10 GHz around Building

This research described the Doppler shift effect for the communication systems. The mobile station moves with various velocities around the building’s environment. Doppler’s shift influences the communication systems. The frequency communication was used 10 GHz and its influenced by atmospheric attenuation. This research consisted of propagation with LOS and NLOS conditions, mobile station velocity variation, height buildings variation, and transmitter power variation. This research described frequency maximum at Doppler shift, coherence time, and signal to noise ratio. More increase Doppler shift of coherence time caused signal noise ratio to decrease.

130 Jurnal Infotel Vol. 12  at the track with random velocity. The location communication took place around the building environment. That communication was caused by building existence. This research analyzed some variations such as LOS and NLOS, velocity variation of the mobile station, and power transmitter variation. Power transmitter variation consists of 20 dBm, 25 dBm, and 30 dBm, transmitting the characteristic at a maximum output power of the base station [22]. The building influenced NLOS condition. That building was modeled with different high. As a result, shows frequency value from the Doppler shift effect toward the mobile station was random velocity, coherence time from Doppler shift for communication when LOS and NLOS condition, and signal to noise ratio value.

A. Environment Model
The frequency communication used 10 GHz. That frequency was influenced by atmospheric attenuation, such as oxygen and water vapor. Atmospheric attenuation parameter of A was s was showed at (1). As shows in parameter gaseous attenuation, and was path length (km) [23].
The movement of the mobile station at the track showed in Fig. 1. Figure 1 also shown mobile stations around the building environment. The obstacle at communication was caused by high building. The building height model was used around 10 meters until 20 meters, shown in Fig. 2. The road is modeled with a comprehensive road of 8 meters that consisting of sidewalk space and a long track for the mobile station of 600 meters.
The mobile station moved through 600 meters long track with various velocities. The velocity was used around 20 km/hour until 90 km/hour. This communication propagation was observed Doppler shift influence. The mobile station's movement was related to Doppler shift, that signal spectrum entirely would movement to frequency. The Doppler shift was affected by mobile communication system performance. The movement of the mobile station caused the Doppler effect of shift frequency. Angle-of-Arrival (AoA) was the definition of AoA direction obtained from mobile station movement direction toward base transceiver station. The equation for Doppler frequency or Doppler shift was shown in (2).
parameter was the frequency maximum of Doppler shift at the nth path, based THE angle from the mobile station [24].
The decision of maximum frequency at the Doppler effect is shown in (3) [21]. As shown in the parameter, it was the maximum frequency of Doppler shift (Hz), ∆ was velocity (m/s), and was wavelength (m).
The coherence time was time duration over the channel impulse response. The coherence time parameter of Tc (s) was shown in (4) [25].
The noise equation parameter of N was shown in (5). That equation existed some parameter was consisting of Boltzmann constant value (K), bandwidth parameter (B), signal to noise ratio (SNR), To was standard noise temperature (290 o K), and F parameter was noise figure [24]. As shown in F, the value used 7 dB, and bandwidth used 5 MHz.
The effect of building environment used single knife-edge method. Representation of Fresnel Kirchhoff was showed in (6). Parameter v, λ, h, d1, and d2 were represented Fresnel Kirchhoff, wavelength (m), diffraction height (m), transmitter distance toward diffraction node, and receiver distance toward diffraction node (m).
The transmitter power variation consists of 20 dBm, 25 dBm, and 30 dBm. SNR value is shown in equation (7). The SNR, S, and N parameter was represented by signal to noise ratio (dB), signal, and noise power.        Figure 6 shown the SNR value for LOS and NLOS conditions. Parameter of described transmitter power. The equation used for that result is based on the Signal to Noise Ratio (SNR) (7), diffraction for LOS and NLOS as in (6). Table 1 shown some data communication propagation from Fig.6. The transmitter power used consists of 20 dBm, 25 dBm, and 30 dBm. Some data from Table 1