SUMMARY:

BLUETOOTH TECHNOLOGY:-
o Bluetooth is designed to be a personal area network, where participating entities are mobile and require sporadic communication with others.
o It’s omni directional.
o Bluetooth operates in the 2.4 GHz area of the spectrum, and provides a Range of 10 meters.
o It offers transfer speeds of around 720 Kbps.
o Bluetooth devices are connected to each other; they form a network called Piconet. Each piconet can have a master, and up to seven slaves.
o To accommodate interference from other signals, Bluetooth uses frequency hopping.
o To conserve power, devices can go into three modes when they aren’t actively involved in a piconet.
o In increasing order of power consumption, they can be in park mode, hold mode and sniff mode.
o All the slave devices in a piconet are assigned an active member address(AM_ADDR).when a slave enters the park mode; it will give up its AM_ADDR and get a park address, PM_ADDR.
o One of Bluetooth’s advantages is that it can handle both data (asynchronous) and voice (synchronous), which others such as infra-red can’t.
o Every Bluetooth devices has a 48-bit BDAddr (Bluetooth device address) burned into its ROM. This address can’t be easily changed by the user.
o A Bluetooth device can be set to periodically scan for other devices in its vicinity or users can perform manual scans.

WI-FI TECHNOLOGY:-
o Bluetooth is a convenient way of communication for a personal network, but it is not suitable as an LAN replacement, or for perennial data transfer.
o Wi-Fi and abbreviation for wireless fidelity, is a wireless standard that promises mobility while offering data rates comparable to those of a wired LAN.
o Wi-Fi is a collection of standards ratified by the IEEE. In 1997; IEEE approved the 802.11 standard, which laid down the specification for wireless LAN.
o Revisions were made to this standard and these resulted in three other standards, namely 802.11a, 802.11b and 802.11g.The entire family of 802.11 standards is collectively called Wi-Fi. The name Wi-Fi was first given to the 802.11b standard. Approved in 1999, 802.11b Offered extensions to the original 802.11 that improved the highest data rate from 2 Mbps to 11 Mbps. It operates in the 2.4 GHz frequency range, like as the original and has a range of about 300 feet. The latest is 802.11g that has the highest data rate of 100Mbps.
o 802.11a is a standard that operates at a frequency of 5 GHz, and hence it is incompatible with 802.11b.
o The range of 802.11a is lower than that 802.11b; hence, more access points are needed to cover a large area.
o 802.11a is less susceptible to interference when compared to other standards such as 802.11b.
o To solve the limitation of ‘b’ and at the same time provide the speed of ‘a’, the 802.11g was introduced.
o 802.11g offers speeds of 100 Mbps, while maintaining compatibility with 802.11b networks, while maintaining compatibility with 802.11b networks, so a laptop with an 802.11g card will be able to use an 802.11b access point.
o Wi-Fi has a basic level of security provided at the physical level, called WEP.
o All Wi-fi products come with a 40-bit encryption key. A 104-bit encryption key is also available, and it is recommended that the largest available key should be used.

DATA RATE, THROUGHPUT AND RANGE

As Bluetooth and Wi-Fi were designed to serve differing usage scenarios, it is no surprise that the performance of the two systems differs as well. Bluetooth trades off speed for lower power consumption, whereas Wi-Fi attempts to match the performance of wired LANs. Bluetooth supports two types of links – packet and connection-oriented (known as SCO). Packet connection is used for data transmission and can operate symmetrically or asymmetrically. The maximum symmetric data transfer rate is 433.9 kbps in each direction; the maximum asymmetric data rate is 723.2 kbps upstream (57.6 kbps downstream). Dedicated connection-oriented links are used for audio applications. Bluetooth can support three 64 kbps voice channels simultaneously. These data rates are sufficient to accommodate the usage scenarios described in earlier sections. Wi-Fi supports four different data rates: 11 Mbps, 5.5 Mbps, 2 Mbps and 1 Mbps. A ratescaling algorithm is used to reduce the data rate when errors are detected in transmission. The result is that the data rate is reduced as a user moves farther away from an AP.

CONNECTING
When a user wishes to connect to a LAN, Wi-Fi offers a simpler procedure, as it has been optimized for this function. Assuming a WLAN card is already in place, the user need merely turn on her computing device and enter the necessary authenticating user name and password. The user is then on the network. For Bluetooth, the process is lengthier, possibly requiring each of the following steps: 1) device discovery; 2) device connection; 3) the establishment of a LAN access connection; 4) the establishment of a PPP connection; 5) PIN entry; 6) network user name and password entry. Though most of these steps can be accomplished with a single click of the mouse or tap of the stylus, the entire process could take as long as 30 seconds. The fact that Bluetooth enables communication between disparate device types using many different types of applications means, inevitably, that some procedures will take longer with Bluetooth than with applicationspecific technologies such as Wi-Fi. In order to streamline this process, Pico has developed a proprietary application -- PicoConnect™ -- that allows onetouch network access.

COMPARING THE CAPABILITIESOF BLUETOOTH AND WI-FI:

POWER CONSUMPTION
Power consumption is a critical consideration as it directly affects device battery life. This consideration is obviously most crucial for devices that spend most or all their operating hours on battery power – devices such as PDAs and mobile phones. From its inception, Bluetooth was designed to be a small-form factor, low-cost, low-power technology. The Bluetooth specification incorporates a number of power saving features in order to keep power use to a minimum. These features include a standby mode as well as four connected modes – parked, hold, sniff and active. An adaptive transmission power feature further minimizes power use.

In order to achieve Ethernet-level data rates, Wi- Fi operates with higher radio power on fixed channels of greater bandwidth. Wi-Fi offers a power save mode in which STAs “sleep,” then reawaken periodically to check for messages. Bluetooth and Wi-Fi modules are available in many different form factors including PC cards 9PCMCIA), Compact Flash (CF) cards, Secure Digital (SD) cards, Springboard modules, PCI cards and mini-PCI cards. Table 1 below summarizes the power requirements of various Bluetooth and Wi-Fi devices classes under various operating modes.

As shown in the table above, current Bluetooth devices have a minimum current that is approximately one-tenth the amount of minimum Wi-Fi current requirements, and a transmit current as little as a tenth of Wi-Fi’s transmit current, depending upon the output power of the devices in question. The implication is that Bluetooth will drain the battery less quickly than will Wi-Fi, making Bluetooth a more attractive option for users with smaller devices. In fact, a typical PDA with a 500 mA-hr battery life could support Bluetooth running in idle mode for more than 250 hours, whereas Wi-Fi could only be supported for 20 – 50 hours in sleep mode. If both technologies were in full transmit or receive mode, a PDA using Wi-Fi could expect little more than an hour of operation while a PDA using Bluetooth could operate for five to ten hours.

PRACTICAL IMPLEMENTATION OF WI-FI TECHNOLOGY:

In this report we show you how we
created a Wi-Fi network using 2.4 GHz USB
Wireless Adapter DWL-122 and DI-
614+2.4GHz Wireless Router 5V DC Power
Adapter. Thus we can access the laptop from a
Wi-Fi PDA through the access point. The LAN
can also be accessed through it. We have also
created a peer-to-peer network to link up a Wi-Fi
enabled PDA and a laptop directly without the
access point. The following section explains how
to configure the network.

HOW WI-FI WORKS:

SYSTEM SUPPORT:
For a system to connect to a Wi-Fi
network, it should have a Wi-Fi card, or an
access point connected to it. Wi-Fi network cards
are like normal network cards that plug into PCI
slots, but have a protruding antenna. It’s also
possible to plug an external Wi-Fi adapter into a
USB port. Once network card are installed and
configured, the system can connect to any Wi-Fi
network.
PROS:
Given the current situation, Wi-Fi
should be adopted when there is a demand for
High speed on the move. Wi-Fi is suited for
corporate with several executives roaming
around the office with their laptops. Home
looking for a means to share a broad band
internet connection can also consider adopting
Wi-Fi.
CONS:
A wireless setup is rather expensive
when compared to a regular LAN. Also since
Wi-Fi drains batteries much quicker, PDA users
should avoid using it-especially if they have a
Bluetooth option available. It is difficult to
provide Wi-Fi network, as it is difficult to
control access to the network.
DEVICE USING WI-FI:
While Wi-Fi may be widely used for
communication between computers, there are
PDAs that support it. It’s also possible to add
Wi-Fi support to a PDA by inserting a Wi-Fi
card in to the SD (secure Digital) slot. PDA such
as the Toshiba e750 have inbuilt support for Wi-
Fi. Nokia announced plans to build mobile
phones that can seamlessly switch between
802.11b and public networks. The major
problem with Wi-Fi is the high power
consumption, which mobile devices just can’t
afford.