Wireless Media – Exclusive Introduction

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

Nowadays, Cellular phones, Global Positioning Systems (GPS), Cordless Mouse, Cordless Keyboard, Cordless telephone sets, remote controls, Satellite televisions, 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 points to consider before planning:-

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

Types of Wireless Media

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

• Transmission Frequency
• The transmission power of the 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 is commonly referred to as Wi-Fi. WLAN uses a protocol called 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, the NIC must wait until the channel is clear. We will briefly discuss CSMA/CA.

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), it uses a point-to-multipoint topology to provide 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 interconnection point 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, several WLAN Ethernet-based standards have emerged. So, care needs to be taken when purchasing wireless devices to ensure 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.