Bluetooth architecture.

Bluetooth is a wireless technology standard which is used to connect gadgets without a cable. The Bluetooth module is a small part of the chip in a device, which lets it wirelessly communicate with a Bluetooth module on any other devices.

• Generally speaking, Bluetooth is used to transfer small amounts of data while being efficient with battery usage. 
• Among the various wireless standards (like Wi-Fi), Bluetooth is known for maintaining a stable connection in short distances, and transferring small amounts of data without taking too much power. 
• Bluetooth was invented by a team of engineers working for Ericsson, the networking giant. Ericsson’s Dutch electrical engineer Jaap Haartsen is credited as the inventor of Bluetooth. 
• Haartsen has said he developed the standard in 1994, but hadn’t yet found a name for it.

Connecting With Bluetooth

• Many mobile devices have Bluetooth radios embedded in them. PCs and some other devices that do not have built-in radios can be Bluetooth-enabled by adding a Bluetooth dongle.
• The process of connecting two Bluetooth devices is called "pairing" Generally, devices broadcast their presence to one another, and the user selects the Bluetooth device they want to connect to when its name or ID appears on their device. 
• As Bluetooth-enabled devices proliferate, it becomes important that you know when and to which device you're connecting, so there may be a code to enter that helps ensure you're connecting to the correct device.
• This pairing process can vary depending on the devices involved. For example, connecting a Bluetooth device to your iPad can involve different steps from those to pair a Bluetooth device to your car.

Bluetooth architecture.

The radio layer is responsible for:

• Modulation/Demodulation of data for transmitting (OR) receiving over air.

The base band layer is responsible for:

• Controlling the physical links via radio.
• Assembling the packets.
• Controlling frequency hopping.
• The RF COMM provides a serial interface with wireless application protocol (WAP) and object exchange(OBEX).
• WAP and OBEX provide interface to other communications protocols.
• The link manager protocol controls and configures links to other devices.
• The host controller interface(HCI) handles communication between the host and the module. For this purpose, it uses several HCI command packets such as the even packets and data packets. 
• The L2CAP layer converts the data obtained from higher layers into packets of different sizes.
• The TCS(Telephone control protocol specification) provide telephony service.
• The SDP(Service discovery protocol) allows the devices to discover the services available on another Bluetooth enabled device.
• The applications present in the application layer can extract the services of the lower layers by using one of the many profiles available.

Bluetooth Limitations

• There are some downsides to Bluetooth. The first is that it can be a drain on battery power for mobile wireless devices like smartphones, though as the technology (and battery technology) has improved, this problem is less significant than it used to be.
• Also, the range is fairly limited, usually extending only about 30 feet, and as with all wireless technologies, obstacles such as walls, floors, or ceilings can reduce this range further.
• The pairing process may also be difficult, often depending on the devices involved, the manufacturers, and other factors that all can result in frustration when attempting to connect.

How Secure Is Bluetooth?

• In blue tooth connections are encrypted, preventing casual eavesdropping from other devices nearby. 
• Bluetooth devices also shift radio frequencies often while paired, which prevents easy invasion.
• Devices also offer a variety of settings that allow the user to limit Bluetooth connections. 
• The device-level security of "trusting" a Bluetooth device restricts connections to only that specific device. 
• With service-level security settings, you can also restrict the kinds of activities your device is permitted to engage in while on a Bluetooth connection. 
• As with any wireless technology, however, there is always some security risk involved. 
• Hackers have devised a variety of malicious attacks that use Bluetooth networking. 
• For example, "bluesnarfing" refers to a hacker gaining authorized access to information on a device through Bluetooth; "bluebugging" is when an attacker takes over your mobile phone and all its functions.  
• For the average person, Bluetooth doesn't present a grave security risk when used with safety in mind (e.g., not connecting to unknown Bluetooth devices). For maximum security, while in public and not using Bluetooth, you can disable it completely.