Wi-Fi access points are networking devices that link wireless devices to each other or to other devices on the local area network. They can be installed as part of the local area network infrastructure for users to access resources on a LAN (Fitzgerald & Dennis, 2005). Hence, they act as bridges between LAN and wireless devices. Access points broadcast information that flows on the wired LAN; while information received over the air is transmitted on the wired LAN (Held, 2003; Panko, 2003).
19 Wi-Fi providers have various implementation design factors to consider when setting up access points on Wi-Fi networks (Fitzgerald & Dennis, 2005). For example, they must consider the coverage area of the Wi-Fi signal. If the area to be covered is small, network administrators may implement a basic service set (BSS). This comprises one access point to manage the connection communications for all devices within range (Bing, 2002; Carleen, 2003).
However, if the area is large, they may have to connect two or more BSS to the same wired network (LAN) to create an extended service set (ESS). The ESS allows administrators to place more than one access point so that the areas they service overlap slightly, to provide wireless signal coverage over an extended area. This allows users to access Wi-Fi services on the move (Bing, 2002).
Wi-Fi design choices have limitations that may affect the service quality as perceived by users.
For example, using the BSS will only allow the user to access services if they are in coverage range of the signal from that particular access point. Conversely, when using an extended service set, the device connection to one access point terminates, and then establishes a new connection as the user moves away from the coverage area of the BSS access point to the next closest access point (Soyinka, 2010). This may create a lag time during the termination and establishment of the new connection to the nearest access point signal. As a result, the Wi-Fi resources that a user is accessing may fail to load or freeze. People may implement ESS to provide reliable connections to students on the move. However, when few access points are implemented in the ESS, it leads to congestion on the access points. For instance, the Chu and Lin (2006) study reported that students’ ability to roam was limited and there was increased competition for Wi-Fi services, rendering the services inaccessible on campus. As a control measure to deal with the congestion on access points, some universities have limited student Internet usage time to two hours, thus reducing the time students may have preferred to have spent accessing network resources (Tella, 2007).
Other solutions to increase network coverage and range may include the configuration of access points with antennas, or the addition of other access points at the location. Wi-Fi antennas are vital components of access points that pick up incoming Wi-Fi signals or send outgoing Wi-Fi signals (Held, 2003; Reynolds, 2003). Administrators may configure access points with bi- directional antennas to deliver coverage in one specific direction. In addition, they may employ omni-directional antennas to deliver signals in all directions (Soyinka, 2010). As such,
20 administrators may have to consider their choices on available antenna types at access points as they may influence the availability of Wi-Fi signals at a location.
In addition, administrators may need to install many access points in a location, to ensure that Wi-Fi users get strong Wi-Fi signals in the Wi-Fi service area. A major challenge is that, after installallation of an access point at a location, the environment may undergo physical changes like construction and re-modelling. As a result, physical obstructions like walls, trees, cardboard or any other material may interfere with the Wi-Fi signal (see Figure 4 and Figure 5). For instance, Călin-Alexandru et al. (2015) analysed how local wireless area networks operate in an environment with several building. The results showed that the width of floor concrete limited the strength of the Wi-Fi signal in one of the on-campus buildings. This result implies that a person with a clear line of sight has a higher chance of getting good signal quality than a person in an environment surrounded by obstacles. Wi-Fi users may need to change their positions, avoid obstacles and move closer to the access point to receive better signal quality.
Unlike signals travelling on local area networks that take one path to the destination device, signals traveling on Wi-Fi networks can use multiple paths as they reflect and bounce off obstructions. In fact, two or more signals may arrive at the Wi-Fi device, one being the direct signal, the other being a reflected signal (O'Hara & Al, 2005). These signals cause multipath effects like delays and reduction in signal strength because they will arrive at different times and have different path lengths (Held, 2003). As a solution, administrators may need to install repeaters to receive a weak Wi-Fi signal, amplify it and then re-transmit the boosted signal to devices (Repeaterstore, 2017).
In conclusion, setting up a Wi-Fi network is a complex matter. Wi-Fi administrators need to make a continual assessment of the performance of the Wi-Fi network to identify possible factors that may limit the delivery of quality Wi-Fi services. However, this requires the co- operation of Wi-Fi users to report any connection difficulties at Wi-Fi locations.
Access points require a networking medium to provide a path over which signals must move information between a source and Wi-Fi devices at destination. The electromagnetic spectrum is the network medium on which Wi-Fi networks operate. It defines a range of frequencies (also called the ‘bands’) used to transmit signals over the air (Bing, 2002; Soyinka, 2010). The next section discusses the electromagnetic spectrum.
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