Faculty of Engineering and Built Environment

The 5850-7075MHz band is profoundly utilized for the fixed service such as Terrestrial Systems (TS) and microwave access (WiMAX) in various parts of the world. Nowadays, the High Altitude Platform System (HAPS) became a recognized system in this band. Therefore, terrestrial links are one of the most considerable interference with the HAPS gateway (HAPSGS) links. Hence, the legitimated interference level between HAPS and TS must be investigated to prevent performance degradation to both systems. This paper investigates the compatibility between HAPS and TS for microwave access (WiMAX) when both systems operate in co channel sharing scenario. This is done by evaluating the downlink (DL) and uplink (UL) performance of both systems. The compatibility results are based on the theoretical derivation of spectrum sharing scenario between HAPS and Terrestrial WiMAX user (TS) located in the coverage area of HAPS in high rain attenuation areas by using the deterministic methodology. This assessment has been executed in the urban area elevation angle. The performance of the system is evaluated in terms of interference to noise ratio (INR) of TS receiver inside the urban area coverage (UAC) of HAPS. Based on the study results, the minimum separation distance should be between 15 to 18 kilometers away from the reference point (i.e. Nadir Point (NP)). The isolation technique is applied in the distances less than 15 km and above 18 km in order to mitigate the interference. Consequently, the maximum isolation values should be 30.92 dB and 13.4 dB inserted between the FS and HAPS Gate Station (HAPSGS) and HAPS airship (HAPSAS) respectively to prevent the co-channel interference.

The development of sharing spectrum between High Altitude Platform System (HAPS) and Terrestrial System (TS) in the 5.8 GHz band is the paper main aim. This paper focuses on Automatic Transmitting Power Control (ATPC) as an interference mitigation scheme capable of utilizing the spectrum sharing between the HAPS and TS operating in the 5.8 GHz band. We employ the ATPC as a fundamental mitigation technique that can reduce the transmission power from a HAPS airship (HAPSAS) or HAPS gate station (HAPSGS). Although customarily, the ATPC techniques have been utilized to conflict rain attenuation by increasing or decreasing the transmission power, we utilized it to mitigate the co-channel interference (CCI) from HAPS into the TS, since both systems operate in the spectrum below the 11 GHz band with negligible rain attenuation. Hence, deep discussion on the interference analysis procedure and interference mitigation possessions from both HAPSAS and HAPSGS is done. Our paper presents the performance of an ATPC in a sharing scenario containing HAPS and TS operating in the same frequency band. The performance of the TS system is evaluated based on the Interference-to-Noise Ratio (INR) level. Accordingly, results show that the adjusted power between −46.1 and −13.67 dBW/MHz is required for HAPS to achieve the coexistence with TS at 5.8 GHz band. Our results can enhance the spectrum sharing between the two services, and thus the spectrum can be utilized more efficiently.

The High Altitude Platform System (HAPS) which will provide a worldwide connectivity in wireless networks operates in 5850-7075 MHz spectrum endorsing the safety of primary services such as terrestrial systems (TS). The suppleness and innate characteristics of HAPS made it a trustable system that can adapt itself to operate as a secondary system in this allotment. To efficiently develop the restricted resources of the radio spectrum, the spectrum has to be divided into sub-channels to be reused. This paper offers the status of a feasibility study on the Dynamic Channel Assignment (DCA) in the mentioned band. In contrast to other mitigation techniques, the DCA technique is likely to evade either causing or accepting interference from/to TS by seeking for a part of a spectrum that is vacant so far; hence, sensing carriers transmitted from TS is the most critical issue in this technique. In this paper, a computer simulation is dispensed to assess the effect of deploying the HAPS as a secondary activated system that shares the band with TS. The paper utilizes the DCA scheme to mitigate the interference caused by HAPS into TS in order to share the spectrum between the two services. Additionally, the possibility of assigning DCA and the ability of sensing signal a victim time by the HAPS gateway (HAPSGS) with separation distance of up. 6 km is proven In order to enhance the DCA performance, the sensing threshold level is diminished from 1dB to 0.3 dB. Accordingly, the feasibility of DCA improved from 6 km to 7 km far from the urban edge of coverage (EOC) area of HAPS.