Wire Free Services

Emerging Technologies in wireless networking

joellivz — Tue, 14 Jul 2009 09:47:57 +0000

Wireless LANs have become mainstream over the last few years. What started out as cable replacement for static desktops in indoor networks has been extended to fully mobile broadband applications involving moving vehicles, high-speed trains, and even airplanes. An increasing number of municipal governments around the world and virtually every major city in the United States are financing the deployment of 802.11 mesh networks, with the overall aim of providing ubiquitous Internet access and enhanced public services.

RF Design Of Wireless Systems

joellivz — Sun, 05 Jul 2009 13:51:19 +0000

The RF dessign needs the basic Knowledge in some of the illustrated fields. All theses studies are together used for the Design flow of a RF design of a system.

Wireless Intro

joellivz — Sat, 04 Jul 2009 12:37:12 +0000

Wireless communication is one of the most vibrant research areas in the communication field today. While it has been a topic of study since the 60’s, the past decade has seen a surge of research activities in the area. This is due to a confluence of several factors. First is the explosive increase in demand for tetherless connectivity, driven so far mainly by cellular telephony but is expected to be soon eclipsed by wireless data applications. Second, the dramatic progress in VLSI technology has enabled small-area and low-power implementation of sophisticated signal processing algorithms and coding techniques. Third, the success of second-generation (2G) digital wireless standards, in particular the IS-95 Code Division Multiple Access (CDMA) standard, provides a concrete demonstration that good ideas from communication theory can have a significant impact in practice. The research thrust in the past decade has led to a much richer set of perspectives and tools on how to communicate over wireless channels, and the picture is still very much evolving.There are two fundamental aspects of wireless communication that make the problem challenging and interesting. These aspects are by and large not as significant in wireline communication. First is the phenomenon of fading: the time-variation of the channel strengths due to the small-scale effect of multipath fading, as well as larger scale effects such as path loss via distance attenuation and shadowing by obstacles. Second, unlike in the wired world where each transmitter-receiver pair can often be thought of as an isolated point-to-point link, wireless users communicate over the air and there is significant interference between them in wireless communication. The
interference can be between transmitters communicating with a common receiver (e.g. uplink of a cellular system), between signals from a single transmitter to multiple receivers (e.g. downlink of a cellular system), or between different transmitter-receiver pairs (e.g. interference between users in different cells).

Wire free Services

joellivz — Sat, 04 Jul 2009 08:19:48 +0000

Wireless does not mean sparks, noise, or a lot of switches. Wireless means communication without the use of wires other than the antenna, the ether, and ground taking the place of wires. Radio means exactly the same thing: it is the
same process. Communications by wireless waves may consist of an SOS or other messages from a ship at sea or the communication may be simply the reception of today’s top 10 music artists, or connecting to the Internet to check your email.It does not become something different in either spelling or meaning.

A simple timeline in Wireless Technologies evolution

1896 Guglielmo Marconi develops the first wireless

telegraph system

1927 First commercial radiotelephone service operated

between Britain and the US

1946 First car-based mobile telephone set up in St. Louis,

using ‘push-to-talk’ technology

1948 Claude Shannon publishes two benchmark papers on

Information Theory, containing the basis for data compression (source encoding) and error detection and correction (channel encoding)

1950 TD-2, the first terrestrial microwave

telecommunication system, installed to support

2400 telephone circuits

1950s Late in the decade, several ‘push-to-talk’ mobile

systems established in big cities for CB-radio, taxis,

police, etc.

1950s Late in the decade, the first paging access control

equipment (PACE) paging systems established

1960s Early in the decade, the Improved Mobile Telephone

System (IMTS) developed with simultaneous

transmit and receive, more channels, and greater
power

1962 The first communication satellite, Telstar, launched

into orbit

1964 The International Telecommunications Satellite

Consortium (INTELSAT) established, and in 1965
launches the Early Bird geostationary satellite

1968 Defense Advanced Research Projects Agency – US

(DARPA) selected BBN to develop the Advanced

Research Projects Agency Network (ARPANET),

the father of the modern Internet

1970s Packet switching emerges as an efficient means of data

communications, with the X.25 standard emerging

1977 The Advanced Mobile Phone System (AMPS), invented by Bell Labs, first installed in the US with
geographic regions divided into ‘cells’ (i.e. cellular telephone)

1983 January 1, TCP/IP selected as the official protocol for the ARPANET, leading to rapid growth

1990 Motorola files FCC application for permission to launch 77 (revised down to 66) low earth orbit communication satellites, known as the Iridium System (element 77 is Iridium)

1992 One-millionth host connected to the Internet, with the size now approximately doubling every year

1993 Internet Protocol version 4 (IPv4) established for reliable transmission over the Internet in conjunction with the Transport Control Protocol (TCP)

1994-5 FCC licenses the Personal Communication Services (PCS) spectrum (1.7 to 2.3GHz) for $7.7billion

1998 Ericsson, IBM, Intel, Nokia, and Toshiba announce they will join to develop Bluetooth for wireless data

exchange between handheld computers or cellular phones and stationary computers

1990s Late in the decade, Virtual Private Networks (VPNs) based on the Layer 2 Tunneling Protocol (L2TP)

and IPSEC security techniques become available

2000 802.11(b)-based networks are in popular demand

2000-1 Wired Equivalent Privacy (WEP) Security is broken. The search for greater security for 802.11(x)-based networks increases