Metodología Enseñanza para la Comprensión

What is the Physical Channel Properties of AtG and D2D links?

Under this research question, we investigate the physical channel characteristics required for node cooperation, mainly focusing on the path-loss and the large scale shadowing (slow fading). The investigation is conducted under three different applications:

1. The first application residing under this research question is the air-to-ground (AtG) media, which is considered as an essential channel for future wireless networks, and for disaster relief aerial coverage, modelling AtG channel includes the investigation of the statistical behaviour of radio signals in terms of the path loss and the shadowing. The target frequency band is 400-6,000 MHz, and the target environments are urban built up areas.

2. The second application related to this research question is focussing on investigating the propagation properties of Millimetric wave band in different urban environments. These properties include the statistical modelling of the expected path loss i.e. to find a relation between the statistical parameters of the propagation and the urban environment properties (as defined by ITU-R [94]). Furthermore, we investigate the utilization of some techniques and methods that can overcome the specific propaga- tion impairments in the mmWave band, techniques as beam forming.

3. The third application area is the current wireless networks were we focus on node cooperation experimental channel measurements in realistic circumstances in differ- ent urban environments. That is, the investigation of the path-loss exponent and the standard deviation of the node cooperation channel.

4. The fourth application is to identify spectrum opportunities for node cooperation, since spectrum scarcity is increasingly becoming an urgent issue, imposing a tough impediment on both wireless service providers, and on regulatory authorities alike, leading to an increasing spectrum fees and inhibiting wireless technology from cop- ing with the growing users-demand. The main driver of this scarcity is the increasing

vast reliance on wireless communication as a ubiquitous means of communication, coupled with low utilization efficiency of the electromagnetic spectrum. Several mea- surement campaigns observed a low spectrum utilization [72, 76], albeit the current scarcity and the soaring spectrum fees. This under-utilization is mainly referred to legacy wireless systems, where spectrum right-of-use is restricted to a single opera- tor (or user) running a low efficiency wireless system. Alternatively, more efficient spectrum utilization can be achieved by exploiting one or more of the radio resource domains in a non-static manner, these domains span over frequency, time and space.

Contributions Under Research Question 1

The key deliverables by the author under this research question formed the following pub- lished papers:

1. Akram Al-Hourani, S. Kandeepan, and A. Jamalipour, "Modeling Air-to-Ground Path Loss for Low Altitude Platforms in Urban Environments", in IEEE Global Com- munications Conference (GLOBECOM), Austin, USA, 2014, pp. 2898-2904. DOI: 10.1109/GLOCOM.2014.7037248 (Published) [123]

This main contribution here is a novel propagation model for air-to-ground coverage in urban environments, the model quantifies the statistical parameters of the path-loss and the shadowing. These parameters are obtained as a function of the elevation angle and the ITU urban environment statistics [94].

2. Akram Al-Hourani, S. Chandrasekharan, and S. Kandeepan, "Path Loss Study for Millimeter Wave Device-to-Device Communications in Urban Environment," in IEEE International Conference on Communications (ICC), Sydney, Australia, 2014, pp. 102-107, DOI:10.1109/ICCW.2014.6881180 (Published) [124]

In this contribution we provide a simulation-based propagation model for D2D mmWave in urban environments. Namely we determine the path-loss exponent (α), and the shadowing standard deviation. These parameters are obtained as a function of the distance and the ITU urban environment statistics [94].

3. Akram Al-Hourani, S. Chandrasekharan, G. Baldini, and S. Kandeepan, "Propa- gation Measurements in 5.8GHz and Pathloss Study for CEN-DSRC," IEEE Inter- national Conference on Connected Vehicles, Vienna, Austria, 2014, pp. 1086-1091, DOI:10.1109/ICCVE.2014.7297518 (Published) [125]

Under this contribution we conduct extensive field measurement for node cooperation channel taking the effect of a standard vehicle on the path-loss. We determine the path-loss exponent and the standard deviation of the shadowing in different urban environments in the city of Melbourne.

4. Akram Al-Hourani, V. Trajkovic, S. Chandrasekharan, and S. Kandeepan, “Spec- trum Occupancy Measurements for Different Urban Environments”, IEEE European Conference on Networks and Communications, Paris, France, 2015, pp. 97-102, DOI:10.1109/EuCNC.2015.7194048 (Published) [126]

In this contributions, we present the results of spectrum monitoring experiment con- ducted in three different urban environments, characterized with different population density and degree of urbanization, for the greater Melbourne area in Australia. The spectrum occupancy is determined by comparing the received signal level to a certain detection threshold based on the noise power of the measurement tool. The occupancy results are categorized with respect to the surrounding population density as obtained from the Australian Bureau of Statistics [2].

5. S. Chandrasekharan, Akram Al-Hourani, K. Magowe, L. Reynaud and S. Kan- deepan, “Propagation Measurements for D2D in Rural Areas”, in International Conference on Communications (ICC), London UK, IEEE, 2014, pp. 639-645, DOI:10.1109/ICCW.2015.7247253 (Published) [1]

In this contribution we present field measurements for D2D path-loss and shadowing standard deviation in rural environments in Victoria, Australia.