A product whose purpose is to provide a sense of security and safety to its users. It is designed as a personal safety device that can be used in emergency situations.

Operating System

• • Android OS
  • iOS

Bluetooth Reliability
Reliability of packets in Bluetooth will be provided through following means.

The Cyclic Redundancy Check (CRC)

All Bluetooth packets contain a Cyclic Redundancy Check (CRC) field which appears at or near to the end of the packet. CRCs are a commonly used mechanism for detecting cases where transmitted data has been unintentionally changed due to issues like collisions.

When a new packet is formulated by the link layer, a CRC value is calculated by applying the CRC algorithm to the other bits in the packet. The resultant 24-bit value is then added to the packet. On receiving a packet, the link layer in the receiving device recalculates the CRC and compares the result with the CRC value included in the received packet. If the two values are not the same, it is concluded that one or more bits in the transmitted packet have been changed and the packet is discarded. It should be noted that the CRC is not a security mechanism since a packet could be deliberately altered and the CRC easily recalculated.

The Message Integrity Code (MIC)

Bluetooth LE packets may be encrypted. All encrypted packets include a field called the Message Integrity Check (MIC). The MIC is in fact a message authentication code but since the acronym MAC has other uses in the field of communications, in the Bluetooth specification, MIC is used. The MIC is not a reliability feature per se. It is a security feature whose purpose is to enable the detection of attempts to deliberately tamper with the contents of a packet. But since part of our informal definition of reliability is that the data transmitted should be the data received and we acknowledge that changes may be unintentional or deliberate, we include it here for completeness.

Communication of data over Bluetooth® technology makes use of more than one radio channel. Using multiple radio channels makes Bluetooth communication highly reliable in busy radio environments, where collisions and interference are likely to occur.

High Availability

A single Bluetooth chip on phone Case will be a single point of failure (SPOF). If the chip becomes non-functional due to any reason, the Mobile App on the Smart Phone will not be able to send any information to the recipients.

In order to handle the SPOF scenario and achieve High Availability. It essentially means that, there will be two Bluetooth chips and both will be in either Active-Active mode or Active-Passive mode.

Here both the chips will be paired in advance with the Smart Phone Mobile App and Emergency Button will activate both the Bluetooth chips to send “Emergency” messages to Mobile App.

Fault Tolerance

Mobile App is supposed to be functional all the times irrespective of failure in any or all hardware components it accessed.

Graceful  Termination of Hardware Activities:

Mobile App will depend upon the smart phone hardware . If any or all of the hardware components are already being utilized by other Apps then a graceful termination will be required in order to achieve the desired functionality of Mobile App and also the Mobile Phone is into consistent state.

User Level

User is not supposed to force stop the App by any means. User should periodically check if the APP is running.

Weak Tower Signals / No Signal:

Mobile App will keep on retrying for sending the Data until the Mobile Phone battery becomes low (hits 10 percent threshold)