Bluetooth

Bluetooth is a way to achieve wireless communication basically for Adhoc Networks using FHSS (Frequency Hopping Spread Spectrum). In Bluetooth piconet there can be 8 nodes active at a point of time (1 master and 7 slaves) and can have maximum of 255 nodes as parked one. Two or more piconet when communicate form a scatter net.  Development of Bluetooth started with merely connecting peripheral without wires, by some well-known companies like Ericsson, Intel, Nokia etc. Bluetooth has now become a major short range, low power communication technique. There are other wireless communication techniques, viz. IEEE 802.11, Infrared etc. But still Bluetooth is gaining the popularity. Main reasons for that is low range, short power, low cost hardware and many more. Bluetooth uses 2.4 GHz radio frequencies, which is mostly free in different countries. Bluetooth is very popular type of wireless communication but it also has some drawbacks like bluejacking, bluesnarfing, low data rate, Interference etc.

 Introduction

Bluetooth

Bluetooth is a wireless technology designed as a short range, low power connectivity solution for small peripheral, portable, and electronic devices like mobile phones, PDAs, printer, keyboard etc.

Wireless LAN

Wireless networking is a way to connect computers or other devices, either in your home or across long distances, using infrared light or radio frequency signals

There are two types of WLAN:

• A local area network that uses access points to connect computers and devices on the network. This is also called an infrastructure network.
• A computer-to-computer local area network (also called an ad hoc network) with several users in a limited area, such as a conference room. This type of network does not use an access point.

 Bluetooth is now days a major technology for Adhoc networks. It can also be used in “infrastructure based” wireless communication system. Bluetooth uses 2.4 GHz unlicensed radio frequency for communication

History

IN 1994 a mobile manufacturing company Ericsson became interested in connecting its mobile phone to other devices without cables. It together with some companies like Nokia, Toshiba, Intel, IBM etc. make a group called SIG i.e Special Interest Group and named the project as BLUETOOTH. The main aim is to develop a short range, low power, and inexpensive wireless radio communication standard. Project is named after a king who tried to unite the Denmark and Norway. There are some IEEE standards, which resembles with Bluetooth but the main thing about Bluetooth is that its specification is for complete system, from physical layer to the application layer. But for example the specification of IEEE 802.15 standardize only physical and the data link layer: and the rest of the protocol stack is not under consideration

The Bluetooth Special Interest Group (SIG) is a trade association comprised of leaders in the telecommunications, computing, automotive, industrial automation and network industries that is driving the development of Bluetooth wireless technology The Special Interest Group was founded in September 1998.

Some specification of Bluetooth

• Operates in the 2.4 GHZ band which is globally available
• It has 79 channels

• Uses FHSS ,GFSK modulation
• 1600 hops per second
• Can support up to 8 devices in a piconet
• Omni-directional, non line of sight transmission through walls
• 10m to 100m range
• Low cost, $20
• 1mW power
• Extended range with external power amplifier (100 meters)
• Difference
• 
  
  There are many other wireless communication techniques are available in the market like IEEE 802.11 (Wi-Fi), IrDA, GSM, GPRS etc. But still Bluetooth is very popular among them. There are many reasons like some techniques required huge infrastructure like GSM, GPRS etc. and also they are not suitable for Adhoc networks like Bluetooth. But some wireless communications techniques are there that are the competitors of Bluetooth. Some main competitors are IEEE 802.11 and IrDA (Infrared Data Association). In this section we will discuss the differences b/w these and Bluetooth.
  
  
  
  
  ·        IEEE 802.11
  
  
  It is a family of IEEE standards for wireless LANs that were designed to extend 802.3 (wired Ethernet) into the wireless domain. The 802.11 standard is more widely known as "Wi-Fi". Based on the Bluetooth Specification, is now an IEEE standard under the denomination of 802.15 WPANs
  
  
  The first 802.11 specifications were introduced in 1997 and included two spread spectrum methods for transmission in the unlicensed 2.4GHz band: 1 Mbps frequency hopping (FHSS) and 1 and 2 Mbps direct sequence (DSSS).
  
  
  11b
  In 1999, 802.11b boosted speed to 11 Mbps using DSSS. The 1 and 2 Mbps DSSS modes are still valid, and devices can throttle down to the lower speeds to maintain a connection when signals are weak.
  An 802.11 system works in two modes. In "infrastructure" mode, wireless devices communicate to a wired LAN via base stations known as "access points." Each access point and its wireless devices are known as a Basic Service Set (BSS). An Extended Service Set (ESS) is two or more BSSs in the same subnet.
  In "ad hoc" mode, also known as "peer-to-peer" mode, wireless devices communicate with each other directly without an access point. This is an Independent BSS (IBSS).