Wireless Media

Wireless media carry data in the form of electromagnetic signals using radio or microwave frequencies. It provides the best mobility options, and the number of wireless-enabled devices continues to increase. As network bandwidth options increase, wireless is quickly gaining in popularity in enterprise networks.  The first wireless transmitter went on air on the 20^th century using Morse Code.

Nowadays Cellular phone, Global Positioning System (GPS), Cordless Mouse, Cordless Keyboard, Cordless telephone sets, remote control, Satellite television, Wireless LANs and some monitoring devices, such as intrusion alarms, employ acoustic waves at frequencies above the range of human hearing also classified as wireless. Wireless does have some important point to consider before planning:-

• Coverage area: Wireless data communication technologies work well in open environments. However, certain construction materials used in buildings and structures, and the local terrain, will limit the effective coverage.
• Interference: Wireless Media is at risk to intrusion and can be disrupted by such common devices as household cordless phones, some types of fluorescent lights, microwave ovens, and other wireless communications.
• Security: Wireless Media communication coverage requires no access to a physical strand of media. thus, devices and users, not authorized for access to the network, can gain access to the transmission. Network security is the main component of wireless network administration.
• Shared medium: WLAN work in half-duplex, which means just one device can send or receive at a time. The wireless medium is shared among all wireless users. The more users need to access the WLAN simultaneously, results in less bandwidth for each user.

Types of Wireless Media

The IEEE and telecommunications industry standards for wireless data communications cover both the data link and physical layers. cellular and satellite communications can also provide data network connectivity. But, we are not discussing these wireless technologies here in this chapter. In each of these standards, physical layer specifications applied to areas that include:

• Transmission Frequency
• The transmission power of transmission
• Data to radio signal encoding
• Signal reception and decoding requirements
• Antenna design and construction

Wi-Fi is a trademark of the Wi-Fi Alliance. The certified product uses that belong to WLAN devices that are based on the IEEE 802.11 standards. Different standards are the following:-

WI-FI standard IEEE 802.11

WLAN technology commonly referred to as Wi-Fi. WLAN uses a protocol known as Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA). The wireless NIC must first listen before transmitting to decide if the radio channel is clear. If another wireless device is transmitting, then the NIC must wait until the channel is clear. We discuss CSMA/CA later briefly.

Bluetooth standard IEEE 802.15

Wireless Personal Area Network (WPAN) standard, commonly known as “Bluetooth”, uses a device pairing process to communicate over distances from 1 to 100 meters.

WI-MAX Standard IEEE 802.16

Usually known as Worldwide Interoperability for Microwave Access (WiMAX), uses a point-to-multi point topology to give wireless broadband access.

Wireless LAN (WLAN)

General wireless data implementation wireless LAN requires the following network devices:

• Wireless Access Point (AP): In a wireless local area network (WLAN), an access point (AP) is a station that transmits and receives data. An access point also connects users to other users within the network and can serve as the point of interconnection between the WLAN and a fixed wire network. Each access point can serve multiple users within a defined network area; as people move beyond the range of one access point, they are automatically handed over to the next one. A small WLAN may only need a single access point; the number required increases the function of the number of network users and the physical size of the network.
• Wireless NIC adapters: Provide wireless communication ability to each network host.

As technology has developed, a number of WLAN Ethernet-based standards have emerged. So, care needs to be taken in purchasing wireless devices to make sure compatibility and interoperability.

The benefits of wireless data communications technologies are clear, particularly the savings on costly premises wiring and the convenience of host mobility