Radio frequency (RF) electronics was originally conceived by Tesla, Marconi and radio pioneers such as Reginald Fessenden, Lee DeForest and Edwin Howard Armstrong as a means for interpersonal communications, either person-to-person, or person-to-people, using analog waveforms containing either Morse code, power or actual sound.

But what these pioneers could not conceive was the capability of radio frequencies (RF) to carry digital data in the form of binary code rather than electronic impulses or voice. The basic underlying technologies that enable wireless digital data communications is the spread spectrum concept envisioned by Hedy Lamarr and George Antheil. Since the 1950s, spread spectrum technology has evolved into two technologies: direct sequence, used mostly in broadband data applications; and, frequency hopping, used primarily for narrowband voice applications.

But it wasn't until spread spectrum technology was demilitarized in the mid-1980s that researchers and developers began to design wireless digital signal transmission technologies to replace the physical wired connections between devices and between devices and broadband wireless networks.

After spread spectrum's demilitarization, the FCC adopted rules for the commercial use of spread spectrum for low power, unlicensed usage in the 902-928 MHz, 2400-2483.5 MHz, and 5752.5-5850 MHz bands of the FM spectrum at a maximum of one-watt peak output. Several European and Asian companies successfully lobbied their governments to allocate similar rules and spectrum space for the development of low power wireless transmission using spread spectrum technology to eliminate interference. As a result, spread spectrum was used to create the Code Division Multiple Access (CDMA) protocol used by cell phones in North America and Asia.

The first commercialized data communications application of spread spectrum was created by the Silicon Valley-based Equatorial Communications in the mid-1980s. The company used direct sequence spread spectrum to enable access to multiple signals from synchronous satellites. Many other companies subsequently developed proprietary spread spectrum wireless data transmission solutions.

In 1990, the Institute of Electrical and Electronics Engineers (IEEE) began work on a wireless Ethernet standard, which would come to be known as Wi-Fi, which would allow several computers within a small area to be networked without the need for physical cabling. The first Wi-Fi specifications, approved in 1997, used both direct sequence and frequency hopping in a 22 MHz swath of the 2.4 GHz band. These new low power local area networks (LANs) allowed data transmission speeds of 2 mbps, and could be used by both stationary and mobile nodes within 90 feet of a Wi-Fi transmitter.

Further improvements led in 1999 to the adoption of IEEE 802.11b, a direct sequence spread spectrum specification with speeds of up to 11 mbps, considered true wireless Ethernet. One of the first mass commercialization of 802.11b was the Apple Airport module, which enabled wireless multi-Macintosh networks. In 2003, several companies started selling "connected" DVD players, media servers and wireless media centers that enabled users to use Wi-Fi to transmit digital music and audio files from their PC to their home A/V systems.

Wi-Fi speed was further accelerated to 54 mbps by the 802.11a specification, also adopted in September 1999. Using the wider 5-GHz bands instead of the 2.4-GHz bands, 802.11a can accommodate more users in a wireless local area network (WLAN), and its higher speed enables multiple channels of video streaming. 802.11g, adopted in early 2003, also pushes transmission speeds to 54 mbps, but uses the 2.4-GHz spectrum, making it compatible with 802.11b and enabling mixed Wi-Fi networks.

However, none of the current Wi-Fi standards are capable of transmitting the thicker high-definition video signals. The new 802.11n standard supplies data rates of 480-540 Mbps with 100-200 Mbps throughput and is designed to be backward compatible with 802.11a/b/g. 802.11n uses a new technology called MIMO (multiple input/multiple output) that would allow one HD stream to be sent to multiple locations over a wider area than the usual 300-foot range, depending on application. However, there are currently four proposed specifications under adjudication, including those proposing using the 5-GHz bandwidth and those using 2.4 GHz. Ratification is scheduled for November 2006, but some pre-certified products already have come to market.

In mid-2003, the IEEE adopted a new wireless home networking standard, 802.15.3, also called WiMedia, designed to distribute standard definition (SD) and high-definition video signals around a home. The 802.15.3 standard features a top raw data rate of 55 mbps at 165 feet, but only 22 mbps speed at 100 meters (330 feet). It automatically changes frequency channels if a channel is already in use by another Wi-Fi wireless device. By the end of 2004, adapters could be available to convert USB 2.0 and IEEE-1394 (FireWire) connections into wireless 802.15.3 connections.

The propagation of individual Wi-Fi networks by individuals, businesses or communities have resulted in larger wireless meshes known as "hot spots." These anarchic wireless areas allow a user to move from Wi-Fi node to Wi-Fi node for uninterrupted Internet access, much the same way that a cell phone call is handed off from cell-to-cell. Airports, government complexes, university campuses, restaurants and cafes such as McDonald’s and Starbucks operate thousands of hot spots. Computer makers are building laptops designed to take advantage of these wireless Internet environments.

There are currently more than 100,000 hot spots worldwide, more than 100 U.S. municipalities, including large cities such as Philadelphia and Seattle, are initiating city-wide Wi-Fi access public utilities, and more than 1000 other municipalities are considering city-wide Wi-Fi networks. However, local telephone and cable monopolies are challenging the right of municipalities to supply services these private companies are attempting to sell. Thirteen state legislatures have passed laws restricting their cities setting up their own networks, and several are considering similar bans.

In 1994, in the middle of 802.11 development, Swedish cell phone maker Ericsson began research on what would become a narrowband wireless personal area network (WPAN) frequency hopping spread spectrum system operating on the 2.4-GHz bandwidth called Bluetooth, named for a tenth century Danish king, Harold Bluetooth.

In 1998, Ericsson, IBM, Motorola, Intel and Toshiba formed the Bluetooth Special Interest Group (SIG). In 1999, 3Com, Lucent, Microsoft and Motorola joined the SIG and the first Bluetooth specifications were published.

Bluetooth is designed to replace the physical connection between devices and peripherals, such as a PDA, digital camera or printer to a PC, or a cell phone headset with a cell phone. The Bluetooth software allows these devices to automatically interact; a PDA would automatically sync its database with its host PC whenever the devices come into range with each other. A Bluetooth wireless personal area network (WPAN) allows devices to intelligently and wirelessly interact with each other within 30 feet at 1 mbps.

In the summer of 1999, the IEEE began efforts to standardize Bluetooth specifications. In March 2002, the IEEE 802.15 Working Group for Wireless Personal Area Networks approved IEEE 802.15.1, which is based on Bluetooth SIG specification version 1.18.

Advanced Bluetooth specifications are being created for a broad array of applications. A large variety of wireless Bluetooth headphones designed to work with Bluetooth-enabled cell phones are available, and in 2005 the first Bluetooth 2.0 EDR (Enhanced Data Rate) stereo-capable products, including headphones and stereo speakers, became available.

While Bluetooth and Wi-Fi are designed to provide clean and secure connections within the 2.4-GHz band, the two technologies can interfere with one another. The proposed IEEE 802.15.2 wireless personal area network (WPAN) specification is designed to facilitate coexistence between the two. In addition, a lower power WPAN technology, 802.15.4, dubbed ZigBee, designed for use in more industrial applications, also has been announced.

In February 2002, the FCC approved limited deployment of an as-yet undefined faster and broader wireless pipeline called ultra wideband (UWB), which would operate on frequency bands from 3.1 to 6 GHz at speeds of 100 to 600 mbps at a distance of 30 feet or less. The wider, faster specification would facilitate the wireless transfer of a two-hour movie in about five minutes, or replace the bulky and unsightly connecting cables between an A/V stack and a wall-mounted flat panel HDTV.

UWB initially was approved for applications such as collision avoidance, ground-penetrating radars and wall-penetrating imaging systems, but questions persist about potential interference with other wireless technologies, such as Global Positioning Satellite (GPS) systems. UWB chip sets enabling more than 600 Mbps became available in 2004 for wireless transmission of HDTV signals.

The IEEE has been attempting to integrate UWB into the IEEE 802.15.3 wireless standard, however this effort has been stalled by competing camps divided by the use of either direct sequence or frequency hopping spread spectrum in the standard. This disagreement also has stalled development of wireless FireWire and USB development. In 2005, the Bluetooth SIG and several UWB developers announced plans to make the two wireless technologies compatible.

In 2003, a new wireless technology called WiMAX, aka 802.16, was announced that is designed to provide so-called "last mile" broadband access. The so-called "fixed" WiMAX standard, 802.16a, provides speeds of around 70 Mbps as far as 10 miles from a single base station capable of serving thousands, and is intended to provide broadband internet access for rural areas, and even third-world countries, where connectivity to far flung cable and telephone wired infrastructure is too expensive. "Mobile" WiMAX, 802.16e, offers theoretical speeds of as high as 15-20 Mbps over one or two miles and is being considered as an alternative to shorter-range Wi-Fi for use in large public spaces. The Mobile WiMAX standard is expected to be finalized in mid-2005 with components by the end of 2006 and deployment sometime in 2007.