Infrared connectivity is an old wireless technology used to connect two electronic devices. It uses a beam of infrared light to transmit information and so requires direct line of sight and operates only at close range.
The Infrared Data Association (IrDA) was established in 1993 to create and maintain international standards for the hardware and software used in infrared communication links. This organisation has created inter-operable interconnection standards, allowing a point-to-point user-access model to benefit the consumer. IR was superseded by Bluetooth, which has the advantage of operating at longer distances (around 30 feet) and being omni-directional.
Many home devices such as TVs and DVD players still use IR remote controls. Some Smartphones are capable of using their IR port to control these devises but that usually requires third-party software. One technological disadvantage is that IR uses a line-of-sight transmission.
Thus, it is sensitive to atmospheric conditions and bad weather, particularly fog.Bluetooth: Bluetooth technology was originally designed in 1994 by two L.M. Ericsson Telephone employees, the Swedish born Sven Mattisson and his Dutch colleague, Jaap Haartsen.
Bluetooth is a short-range wireless technology used for connecting and transferring information between devices such as mobile phones, laptops, PCs, PDAs, printers, digital cameras, mice and keyboards.There are two important parameters of Bluetooth devices - class and supported profiles. "Class" signifies the distance at which a Bluetooth connection is possible.
Most mobile devices are Class 2, which means they have a range of up to 10 m. Class 1 devices are rare and have a range of up to 100 feet. A "profile" is a type of Bluetooth connection. The most common are the Headset (HSP) and Handsfree (HFP) profiles that enable the device to connect to a wireless headset or handsfree. Some other profiles are OBEX (OBject EXchange) which allows transfer of files, contacts and events; A2DP, which adds support for streaming of stereo sound and AVRC, which allows remote control of playback.Bluetooth technology is named after a renowned Danish King, Harold Bluetooth, who was very famous for his traveling exploits. The Bluetooth Special Interest Group (SIG) is the body that oversees the development of Bluetooth standards and the licensing of the Bluetooth technologies and trademarks to manufacturers.
The SIG is a privately held, not-for-profit trade association founded in September 1998. The SIG is headquartered in Kirkland, WashingtonWi-fi: The term Wi-Fi suggests Wireless Fidelity, resembling the long-established audio-equipment classification term high fidelity (in use since the 1930s[) or Hi-Fi (used since 1950). The term Wi-Fi, first used commercially in August 1999.HSDPA: High-Speed Downlink Packet Access (HSDPA) is a 3G (third generation) mobile telephony communications protocol in the High-Speed Packet Access (HSPA) family, which allows networks based on Universal Mobile Telecommunications System (UMTS) to have higher data transfer speeds and capacity. Current HSDPA deployments support down-link speeds of 1.8, 3.6, 7.2 and 14.4 Mbit/s. Further speed increases are planned for the near future. Newly introduced are the High Speed Downlink Shared Channels (HS-DSCH), the adaptive modulation QPSK and 16QAM and the High Speed Medium Access protocol (MAC-hs) in base station.The second phase of HSDPA is specified in the 3GPP release 7 and has been named HSPA Evolved. It can achieve data rates of up to 42 Mbit/s.It introduces antenna array technologies such as beam forming and multiple input multiple output communtions (MIMO).
Beam forming focuses the transmitted power of an antenna in a beam towards the user?s direction. MIMO uses multiple antennas at the sending and receiving side. Deployments are scheduled to begin in the second half of 2008.Further releases of the standard have introduced dual carrier operation, i.e. the simultaneous use of two 5 MHz carrier. By combining this with MIMO transmission, peak data rates of 84 Mbit/s can be reached under ideal signal conditions.
1 comments:
I recently came across your blog and have been reading posts. I thought I would leave a comment. I don’t know what to say except.
phone world
Post a Comment