Mobile Wimax And Fixed Wimax Computer Science Essay

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The Institute of Electrical and Electronics Engineers (IEEE) gave the standards for WiMAX. The standards are given in the specification 802.16 and its variations such as 802.16a, 802.16b, 802.16c, 802.16e etc. 802.16 is the original standard. The 802.16e specification defines the mobile broadband operations. The 802.16f defines the network management used in WiMAX systems. The 802.16g defines the management processes used in WiMAX systems.

IEEE's 802.16 standard is the original standard. The 802.16a gives the fixed wireless broadband standards. The 802.16e gives mobile operation standards. The 802.16f defines network management standards.

WiMAX Forum:

The standards for WIMAX are given in IEEE 802.16 and its revisions. To ensure interoperability of WiMAX products, a non-profit WIMAX Forum was created. This group ensures that the developed WiMAX products are compliant with IEEE 802.16 and are interoperable. It enforces member companies to comply with the standards.

WiMAX frequency range:

The frequency range of 802.16 standards is between 10 and 66GHz. The frequency range of 802.16A standard is between 2 and 11GHz. The vendors may use licensed or unlicensed spectrum of the frequency range.

WiMAX data transmission:

"Data transmission rate refers to the amount of digital information that is transferred over a transmission medium over a specific period of time and is commonly measured in the amount of bits that are transferred per second" - WIMAX Explained by Kalai Kalaichelvan and Lawrence Harte. Data transmission rate of WiMAX depended on different factors such as bandwidth, modulation type and so on.

Mobile WiMAX and Fixed WiMAX:

WIMAX Architecture:

WiMAX systems have Subscriber Stations (SS), Base Stations (BS), Packet Switches, Gateways, and Antennas etc.

A Subscriber Station is a transceiver. A transceiver is made up of transmitter and receiver. As the name suggests, it transmits and receives radio and digital signals. A Subscriber Station uses Frequency Division Duplex, Time Division Duplex or a combination of both. There are indoor and outdoor SS.

A Base Station is another transceiver which connects wireless systems and network backbones. A Base Station should support several SS. There are indoor and outdoor BS.

A packet switch is a device which transmits information as bytes of data. Packet Switches have internal table. When they receive packets, they read the destination addresses in the packets, look up the addresses in their table and forwards the packets to next destination.

Gateway is a connection between networks. It transmits data between network in a format that each understands.

Antenna transmits, receives and converts signals between electrical and electromagnetic form.

The important technologies used in WiMAX systems are frequency division multiplexing, Time division multiplexing, frequency reuse, modulation etc.

Modulation:

is the process of changing the amplitude or phase or frequency of a carrier wave with respect to the modulating signal.

Binary Phase Shift Keying:

Quadrative Phase Shift Keying:

Quadrative Amplitude Modulation:

Orthogonal Frequency Division Multiplexing:

Frequency Reuse:

Licensed Frequency and Unlicensed Frequency:

Quality of Service ( QoS):

WIMAX products:

Broadband communication:

"Broadband communication service is the transfer of digital audio (voice), data, and/or video communications at rates greater than wideband communications rates (above 1 Mbps). Broadband connections allow for the providing of multiple services such as telephone (voice), data, and video on one network." - WIMAX Explained by Kalai Kalaichelvan and Lawrence Harte

Wi-Fi:

The word Wi-Fi stands for Wireless Fidelity. Wi-Fi provides wireless communication over isolated smaller areas like how a LAN does. It works like any other LAN network but without wires. Computers, printers, laptops etc can connect and communicate using Wi-Fi. The major difference between Wi-Fi and WiMAX is that Wi-Fi works for smaller areas. IEEE developed standards 802.11b, 802.11a, 802.11a/g, 802.11n etc for Wi-Fi.

(Reference - WiMAX: A Wireless Technology Revolution by G. S. V. Radha Krishna Rao and G. Radhamani )

Spectral range of Wi-Fi is between 2.4 GHz and 5.8 GHz. Wi-Fi uses unlicensed spectrum so there is disadvantage of interference. Data transmission rate of Wi-Fi is between 1 Mbps to 54 Mbps based on different standards.

Wi-Fi Alliance is an organization which tests and certifies the Wi-Fi products and their interoperability.

In Wi-Fi standards, computers are called stations. 802.11 standards and its revisions talk about two modes: Infrastructure mode and Ad hoc mode. In infrastructure mode, a Wi-Fi Access Point (AP) is connected to a wired network and also to a wireless end stations. Such a connection network is called Basic Service Set (BSS). Several connected BSSs make an Extended Service Set (ESS). Several ESSs can be connected using Data System (DS). A DS is medium to transfer packets between different ESSs. In Ad Hoc mode, different stations connect to others directly. An Ad hoc system can be set up fast but it has several limitations.

Comparison between WiMAX and WI-Fi:

WIMAX Advantages:

Standardized technology - WiMAX Forum ensures that the member companies comply with IEEE 802.16 standards and its revisions. It certifies the compliance and interoperability of the WiMAX products. Standardized technology means easier and faster deployment. This also decreases the cost of the equipments.

Has signal range of several kilometers. Other technologies such as Wi-Fi have signal range in meters.

High data transmission rates.

Can penetrate through trees and buildings

Scalability

The vendors may use licensed or unlicensed spectrum. Using licensed spectrum will decrease interference from other wireless operators.

Provides speed higher than Wi-Fi and signal range is longer than Wi-Fi

WIMAX Limitations:

WIMAX future: