The Application of Land Use/Land Cover (Clutter) Data to Wireless Communication System Design - Sponsored Whitepaper

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Land use/land cover (LULC) data can play a significant of role in designing wireless communication systems. It can be used to improve predictions of signal attenuation and other radio propagation effects and to assist in finding the optimal location of network base stations and other wireless system transmitters. It can also be utilized when projecting usage (traffic) trends in any type of mobile or nomadic system. With literally billions of dollars being spent annually on building wireless communication systems, there is significant incentive to use engineering tools that can accurately and efficiently design and plan such systems. There currently are a number of software tools on the market intended for just that purpose. Considering that a wireless network for a single urban area can be comprised of hundreds of base stations, an efficient system design process can easily justify the expense of the design tool and the effort using it. As the wireless system grows to meet increasing and changing demands for service, the design tool is again a valuable asset in planning optimum modifications to the system to accommodate growth. Of fundamental importance to the wireless system design tool is the ability to accurately predict the strength of radio signals from the various transmitters in the system. The mathematical algorithms used for these predictions are generally known as propagation models. Originally, propagation models relied on terrain elevation data as the sole environment parameter on which to base predictions. Substantial effort has been invested over the last 20‐30 years in developing accurate DTEMs (digital terrain elevation models) for all parts of the world. While terrain has a profound effect on the propagation of radio signals (especially at higher frequencies), more localized features of the environment such as trees and structures (buildings, houses, etc.) also have a substantial impact on propagation. An important trend in wireless system architecture is to use smaller cell coverage areas (so‐called microcells) and much higher radio frequencies where significantly greater transmission bandwidth is available. For such short‐range system architectures where the coverage radius of the transmitter may range from 0.5 to 5 kilometers, the terrain can often be regarded as locally flat. Under such conditions, signal propagation is dominated by local obstructions ("clutter") rather than by terrain, making the description and accurate classification of land use/land cover data of primary importance.

The Application of Land Use/Land Cover (Clutter) Data to Wireless Communication System Design

Radio wave propagation is a physical phenomenon that can be described using electromagnetic wave equations. Like waves travelling away from the spot where a stone has been tossed into a pond, radio waves travel away from the transmitting antenna in all directions. Theoretically it is possible to exactly predict the strength of the signal from any transmitter at any other location if all the elements of the propagation environment are correctly taken into account. In so‐called “free space” (actually a vacuum), there are no elements in the propagation environment and the signal strength at some distance from the transmitter can be exactly calculated. Radio wave transmission through outer space is one region where such a simple formulation applies. For transmitters located on the earth's surface the problem is much more complicated. Every physical entity a radio signal encounters after it leaves the transmitting antenna affects the strength and direction of the signal. The physical entities that affect the signal can be grouped into four broad categories: 1. The atmosphere (or other gaseous media) refracts (bends) and diffracts (scatters) the radio waves; bending changes the direction of the radio wave while scattering generally weakens the wave. 2. Terrain features (hills and mountains) block the radio waves, requiring them to diffract over the top or around the sides, weakening the signal on the other side. Radio waves also reflect and scatter off of terrain surfaces causing a change in the direction of the radio wave. 3. Much like terrain, structures such as buildings, houses, towers, etc. block the radio waves. The waves diffract, reflect, scatter and transmit through structures. 4. The leaves and branches of trees and other types of foliage also weaken radio waves by scattering them, which has a similar effect as that of the blocking them as terrain or buildings can do As mentioned in the introduction, the atmosphere and terrain have been included for many decades in the propagation models which are designed to predict the strength of radio signals. Figure 1 shows a representation of a radio wave propagating from a transmitter (on the left) to a receiver location in the open (on the right).

Figure 1 ‐ Radio Path with Tree Although the signal arriving at the receiver will include some reflections from the ...
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