Receiver diversity with selection combining for drone communication around buildings at frequency 10 GHz

The communication network for cellular network keep development. This research analyzed about cellular network was used drone network. The mobile drone used frequency at 10 GHz for communication. The mobile drone moved around buildings. Buildings were used high variation. Base Station placed around building. This research was using macro diversity Base Station for drone communication with some variations was used such as buildings (5m, 15m, 35m, and 45m), modulation (QPSK, 16 QAM, and 64 QAM). Macro diversity mechanism used for that two Base Station. Selection Combining (SC) method was used for that macro diversity mechanism. The modulation communication based from Adaptive Modulation and Coding (AMC). Adaptive Modulation and Coding (AMC) was used Modulation and coding scheme (MCS). Modulation was used QPSK, 16 QAM, and 64 QAM. As the result described signal to noise ratio (SNR) at every node communication, probability MCS, and percentage coverage of drone trajectory. MCS probability for 64 QAM become increased with selection combining method. The percentages coverage of drone trajectory was obtained 77.2% of the first BS, 66.8% of the second BS, and 87.2% with SC method. The communication drone location was used adjustment of high variation with necessity. Keywordsselection combining; drone; MCS; building; All rights reserved.


A. Environment Model
Mobile drone moved at horizontal trajectory around building. The high drone was used 20 meters. Building environment was modeled with high building variation. Diffraction mechanism also measurement with Fresnel zone. Fresnel zone used range value for diffraction. Propagation communication was used uplink condition. Transmitter was placed at mobile drone. BS was used some RBS. Figure 1 was modeled communication with one RBS every one BS. The drone communication was used BS 1 and BS 2. Two BS was used macro diversity. Selection combining method was used for macro diversity. The high BS was used 30 meters. That figure was used MATLAB for create simulation. Figure 2 was showed buildings variation. The percentages of high building variation were used such as 23% of 5 meters, 23% of 15 meters, 24% of 25 meters, 18% of 35 meters, and 12% of 45 meters. The communication propagation caused by high building. Some building was caused diffraction mechanism with NLOS condition. Figure 3 was showed single knife edge method for diffraction mechanism [23]. That method was used this research because that method accordance with building environment.

B. Single Knife Edge Method
Single knife edge method was used for diffraction mechanism. That diffraction was caused high building with NLOS condition. That high building could influence of SNR communication. Fresnel zone was used range value for diffraction. Single knife edge method was showed at equation (1). λ, v, h, d1, and d2 parameters showed long wave (m), Fresnel Kirchoff, high of diffraction (m), transmitter distance through node (m), and receiver distance through node (m) [23]. NLOS condition caused decrease SNR value at node of mobile drone trajectory. (1) Drone communication system was used Tx with 20 dBm. Uplink condition was used for that communication. Some parameters from equation 1 was showed N, S, and SNR parameters was noise power, signal value, and signal to noise ratio [23]. The equation for SNR was showed at equation 2.

=
(2) N parameter was showed at equation 3. K, B, NF, and T parameters were Boltzman constant, bandwidth, noise figure, and standard noise temperature (290 o K) [23]. NF value was used 5 dB, and B value was used 5 MHz.
Equation 4 was showed atmospheric attenuation. The atmospheric attenuation was influenced by oxygen and water vapor [24]. and parameters were described gaseous attenuation, and path length (km).

III. RESULT
This section described about mobile drone at horizontal trajectory with high of 20 meters. Transmitter power was used 20 dBm. The communication frequency was used 10 GHz. That frequency was influenced atmospheric attenuation. Mobile drone moved around building environment. That building environment was used high building variation. Diffraction was caused by high building. Single knife edge method modeled diffraction mechanism. NLOS condition was used Fresnel zone.     Figure 5 showed SNR communication at drone with high 20 meters. SNR value was obtained from RBS 1, RBS 2, and Selection Combining. Some data was resulted such as drone at 25 meters, drone at 100 meters, drone at 200 meters, and drone at 300 meters. When the drone moving at 25 meters was obtained SNR RBS1 28. 19  two RBS. That selection combining method was obtained increasingly of MCS probability level for 64 QAM. The coverage area percentages were resulted such as RBS1 obtained 77.2%, RBS2 obtained 66.8%, and SC obtained 87.2%. That percentages were showed the highest value of SC method, and MCS probability with SC obtained 0.872 for 64 QAM with 436 nodes. Some node at mobile drone trajectory was obtained the lowest of SNR value. The communication drone location was used adjustment of high variation with necessity.