SciTech

Bluetooth technology connects devices together wirelessly

Credit: Yoon Young Kim/ Credit: Yoon Young Kim/

In today’s media-run world, Bluetooth technology surrounds us in our cars, in our pockets, and on our ears. With its beginnings rooted in the ‘90s, back when people used Nokia 9000s, Bluetooth has revolutionized the way devices communicate wirelessly. With Bluetooth, we can wirelessly play music on speakers from our phones, transfer photos between devices, and so much more. The Bluetooth Special Interest Group originally consisted of five companies: Ericsson, IBM, Intel, Toshiba, and Nokia. Now, it has over 20,000 member companies, and its growth does not show signs of stagnating.

Bluetooth is a wireless technology standard used to exchange data across devices in close proximity. To communicate, industrial, scientific, and medical devices (ISM) send short-wavelength radio waves across 79 designated Bluetooth channels on the globally unlicensed ISM radio frequency band. It is inexpensive, automatic, and low-energy. Even with Bluetooth running in the background of a smartphone, the battery is hardly drained. The most recent Bluetooth standard, version 4.2, has a theoretical maximum speed of 25 megabits per second (Mbps) and a theoretical maximum range of 100 meters, or 330 feet. The upcoming version, 5.0, will have a theoretical maximum speed of 50 Mbps and a theoretical maximum range of 800 meters, over 2600 feet. Bluetooth allows for eight devices to be connected at once, and the devices can automatically detect each other.

Each Bluetooth device has a small computer chip with a Bluetooth radio and software. Communication between devices occurs over networks called piconets, or personal-area networks (PAN) — individual networks of devices connected using Bluetooth protocols. One of the devices becomes the “master,” and all other connected devices act as “slaves.” A master and a slave could switch positions, too; the positions are not rigid. Moreover, while the master can have multiple slaves, as of right now, slaves cannot have more than one master. This type of network is called an ad-hoc computer network — it is spontaneous, decentralized, and does not rely on a pre-existing infrastructure of hardware.

Bluetooth uses a radio technology called frequency-hopping spread spectrum in which transmitted data is divided into packets, and each packet is transmitted on one of the 79 channels. There are “even slots” and “odd slots” of time in which a packet can be transmitted. For single-slot situations, the master transmits data in even slots and receives in odd slots, while the slave receives in even slots and transmits in odd slots. So, if there is more than one slave, how does the master transmit packets to all? Using an algorithm called round-robin scheduling, the master handles each slave without priority in a circular order, and switches rapidly between devices; transmitters change frequencies 1600 times per second. The specs of Bluetooth technology eliminate the problems of infrared wireless technology, which television remotes use.

First, Bluetooth does not need the devices to be in each others’ lines of sight, contrasting with how we need to point television remotes at the television for them to work. The devices only need to be visible in a quasi-optical wireless path, referring to an invisible network in which two things are in the same region. Second, Bluetooth works across multiple devices at the same time, as mentioned before.

While the impacts Bluetooth has had on our society are far from simple, Bluetooth protocols operate with the ideals of simplicity and low cost. As the technology advances, the effects it has will only become more widespread and crucial to our daily lives.