Bluetooth is a electrical device that uses wireless technology on 2.5 GHz ISM (license free) frequency band.It can be used in mobile phones, headsets,portable computers to exchange data to each other without wire.Due to its low cost,low size,low power,radio technology,it becomes popular.Almost,every mobile phone provide Bluetooth technology.
Advantage of Bluetooth
1. Operates in the 2.4GHz frequency band without a license for wireless communication.
2. Real-time data transfer possible for short distance.
3. It can transmite data through obstacles like wall.
4. It supports both point-to-point wireless connections between mobile phones
and personalcomputers, as well as point-to-multipoint connections to any other
5. Bluetooth is a portable devices
6. Compared with other systems operating in the same frequency band,
the Bluetooth radio typically hops faster and uses shorter packets.
7. Bluetooth is actually inexpensive.
8. Bluetooth is standardized wireless, meaning that a high level of compatibility
that means it will connect devices to each other, even if they aren’t the same model.
9. Low energy consumption As a result of Bluetooth using low power signals,
the technology requiresvery little energy and will use less battery or electrical
power as a result.
10.The standard for Bluetooth will allow compatible devices to share data and voice communications.
1. Wireless networking between laptops and desktop computers, or desktops that are in a confined
space and little bandwidth is needed.
2. Peripherals such as mice, keyboards, and printers.
3.Most Cell phones uses Bluetooth technology .They are able to connect to computers, PDAs
and various other devices.
4. The transfer of files, images and MP3, between mobile phones.
5. Certain MP3 players and digital cameras to transfer files to and from computers.
6. Bluetooth technology headsets for smart phones and cell phones.
7. Data logging equipment that transmits data to a computer via Bluetooth technology.
If you want to connect two device through Bluetooth ,’pairing process’ is requiered.Through pairing
two or more Bluetooth devices that recognize each other by the profiles they share.
This is one of the most basic levels of security for Bluetooth devices.
Bluetooth use an encryption algorithm, which is completely and entirely secure. Once the devices pair with each other, they too become entirely secure.
Communication will be successfully if and only if thay are paired.That is why Bluetooth technology is considered to be secure.
Still there is secirity threate because some hackers have developed ways to get around this level of basic security.so, you must have software to prevent hackers from getting in.
CDMA (Code-Division Multiple Access) is a wireless communication protocols.It is called second-generation (2G) and third-generation (3G) wireless communications.CDMA is a form of wireless multiplexing, in which data can be sent over multiple frequencies simultaneously.In a CDMA system, data is broken into packets.Each of packets is given a unique identifier, so that they can be sent out over multiple frequencies and then re-built in the correct order by the receiver.The technology is used in ultra-high-frequency (UHF) cellular telephone systems in the 800-MHz and 1.9-GHz bands.
CDMA uses analog-to-digital conversion (ADC) along with spread spectrum technology. Audio input is first converted into binary elements. The frequency of the transmitted signal is then made compatible with receiver frequency so that it can be intercepted only by a defined receiver. There are trillions of possible frequency-sequencing codes, which enhances privacy and makes cloning difficult.
The CDMA channel is nominally 1.23 MHz wide. CDMA networks use a scheme called soft handoff.It minimizes signal breakup as a handset passes from one cell to another. The combination of digital and spread-spectrum modes of CDMA supports several times as many signals per unit bandwidth as analog modes. CDMA is compatible with other cellular technologies, that supports nationwide roaming.
The first CDMA standard, also known as CDMAone and still common in cellular telephones in the U.S.It offers a transmission speed of only up to 14.4 Kbps in its single channel form and up to 115 Kbps in an eight-channel form. CDMA2000 and wideband CDMA support data many times faster.
CDMA has been used in many communications systems, including the GSM and in the OmniTRACS satellite system for transportation logistics.
Usage in mobile telephony
CDMA has been implementationed with different termology. The original U.S. standard defined by QUALCOMM was known as IS-95.The ‘IS’ referring to an Interim Standard of the Telecommunications Industry Association (TIA). IS-95 is often referred to as second generation cellular(2G). The QUALCOMM brand name CDMAone may also be used to refer to the 2G CDMA standard.
Various companies use different form of CDMA to provide fixed-line networks using Wireless local loop (WLL) technology. This application of CDMA can be found in most parts of the world.