Selection of Technology
The main objective of the EnviroNet project is to proof the concept at the MA IM 2005 degree show. The exhibition runs indoor and the objective is to allow visitors to grasp of the utility of the concept behind EnviroNet. EnviroNet uses User Centred Design (UCD) approach, and even though the development of the application will be ideally implementing a LAS, to gain an appropriate user feedback.
Having decided the server side of the application, an analysis of the possibilities of using one of the previous LAS is carried out.
• Absolute LAS
GPS
Using GPS requires that either mobile phones have a built-in GPS receiver, or an external one that is synchronized to the device. In the first case, mobile phone models that have built in GPS receivers are still rare, and minimum price is over 200 pounds. Handsets with capabilities to communicate to external GPS receivers are more affordable, and a valid package cost around 130 pounds.
In either case, there is a need to build an application able to obtain the GPS data, and parse either to the browser on the client device, or to send it to other application server that communicates with enviroNET, so information about the location can be processed.
Develop those kind of applications require knowledge in software development languages capable of using operating system’s components, like Java, C++, or .NET, depending on the platform in use. Bluetooth which is the common protocol use by GPS external receivers and mobile phones to communicate can only be accessed by application developed using those languages.
GSM Localization
This information is provided by network operators in a charge per request scheme making it considerable expensive for an application like EnviroNet. Furthermore the Applications Programming Interface (APIs) as well as applications able to process this data require the same software development skills that in the case of using GPS.
• Relative LAS
It was considered the possibility of setting up Bluetooth beacons, and creates a triangulation method at least for the degree show. PlaceLab is an Intel research project that aims to provide a framework for developing applications that requires implementing LAS. To overcome the inability of GPS to work indoors, PlaceLab uses relative positioning by listening to fixed radio beacons with unique cell ID like wireless 802.11 networks, GSM cell towers and Bluetooth. The PlaceLab framework applies to commodity hardware like laptops, PDAs and cell phones. Bluetooth beacons can achieve an accuracy of ten meters in PlaceLab, but it takes the client device at least ten seconds to recognise cell ID and other non intended beacons in the environment can interfere in the process.
A review on the different technologies that could be implemented to provide location awareness to EnviroNet has been outlined. The main concern of the research has been to draw the possibilities and limitations of the systems, as well as the feasibility of implementing in accordance to human and economic resources. After the evaluating the different risks involved in taking any of them, the team decided to simulate location awareness at the Degree Show, since the primary goal of the project is to demonstrate that EnviroNet fulfils a need, Location Aware Systems could be implemented with the right resources, and when technology becomes more accurate and easier to implement in mobile phones.
Proof of Concept
Having decided not to incorporate a LAS, but to simulate it to proof the concept, the EnviroNet architecture is depicted in the following diagram.
On the Server Side, the Operating System (OS) is Mac OS X Server, which includes the Apache Web Server that host EnviroNet web documents and make them publicly available to the Internet. These documents are created dynamically following a three-tier architecture.
The Data Storage repository holds information units. The Business Logic layer includes server side scripts that manipulate the information units to meet application requirements. The Presentation Layer is responsible for the interface of EnviroNet.
On the Client Side, the mobile phone the interface is rendered by an XHTML browser that provides interaction capabilities to make request to the Server Side.
Client and Server communicate through the Internet.