### Prototype Conceptualization  
#### 3.1.1 Purpose Statement  
The existing blind-assistance literature and the market segment oriented towards their guidance enables the identification of several types of assistance applications, from solutions that help a person to read information [23; 36] to software solutions that help a person to fully use a computer and its applications [26; 30]. In this context, the purpose of the proposed solution is to provide blind and severely visually impaired persons with information that enables them to navigate in unfamiliar places based on personal guidance and user location specific information. Furthermore, in order to optimize the path, as well as to minimize the risks associated with the movement in unfamiliar locations, the proposed solution aims to be able to detect possible obstacles (i.e., open doors, boxes, chairs, dispensers etc.) in users' paths and to warn them. Another problem that the system aims to address is related to the blind person's ability to maintain a straight direction when it is necessary. Consequently, the system targets to monitor and to provide the users with information about their path and trajectory. 1.2 Visible Light Communications-Based Smart Backpack for Visually Impaired Persons' Assistance: Requirements and Guidelines  
_From users' perspective_, in order to be effective, a human assistance solution should be _useful_ to its users, _versatile and simple to use_, should have a high _users' acceptance_, and should be _cost-efficient_. These are the preliminary requirements that have been imposed for the blind assistance solution. _Usefulness_: In order to be useful for blind persons' assistance, a system should be able to provide its users with information that they are not able to perceive through their sight. Nevertheless, as the environment has a lot of visual information to offer, a system should be able to analyze the available information and should be able to offer only the relevant information. Otherwise, too many data can distract the user's attention, making the system less useful. This implies a careful analysis of the available information and an adequate consideration of the users' needs. _Use simplicity and versatility_: The system should be able to translate visual information into other types of sensorial data, whereas in this case, hearing and touching/sensing are the most straightforward senses that could be used. Nevertheless, as sometimes blind users already rely on their hearing in order to perceive the environment, the system should be able to provide users the possibility to use hearing options only when they want. Another aspect regarding versatility is related to a system's ability to provide additional services and/or functionalities. For example, many successful blind-assistance solutions are applications that can be installed on a smartphone. Their success is based on the fact that the blind assistance function can be integrated on an already useful device, which is now able to provide an additional function. Another aspect related to versatility is related to a solution's ability to remain helpful in as many situations as possible. For example, many GPS-based blind guidance solutions become useless in situations with no GPS coverage, which represents a major issue. _Users' acceptance:_ Many VIP support solutions encounter a common challenge related to their hardware design. To enhance the functionality, numerous sensors are often incorporated. While this approach improves the perception of the user's surroundings, it frequently results in final prototypes that are overly sized and lack aesthetic appeal, making them unaesthetic and uncomfortable for users to wear. Thus, it is obvious that wearing such a conspicuous and bulky device can inadvertently highlight the users' impairment, thereby limiting the device's overall practicality and benefits. _Cost-efficiency:_ Cost-efficiency is a feature that can be attributed to a system that is not necessarily cheap, but whose benefits are high with respect to the cost.