WiMAX Explained: Architecture, Features, and Applications

This article provides an overview of WiMAX (Worldwide Interoperability for Microwave Access), its features, standards, and applications. We’ll cover various aspects, including:

• WiMAX Terminology
• WiMAX Frame Structure
• WiMAX Network Architecture
• WiMAX Physical Layer
• WiMAX MAC Layer Protocol
• WiMAX Protocol Stack
• Advanced WiMAX 802.16m
• Fixed WiMAX versus Mobile WiMAX
• WiBro versus Mobile WiMAX

This will help you understand what WiMAX technology is and how it works. For in-depth information on the WiMAX MAC Layer, you can explore topics like network entry, ranging, QoS, network interfaces, and MAC messages (DLMAP, ULMAP, UCD, DCD, RNG REQ, SBC REQ, REG REQ, DSA REQ, CID, SFID, FCH).

Understanding WiMAX

WiMAX is a technology designed to deliver broadband data connections to users, similar to DSL. The key benefit is its ability to serve both fixed and mobile users. This flexibility is achieved through two primary types of WiMAX:

• Fixed WiMAX: Primarily intended for users at fixed locations.
• Mobile WiMAX: Designed for users on the move, but can also be used for fixed locations. Fixed WiMAX cannot provide mobile services, however.

The core difference lies in the underlying technology: Fixed WiMAX relies on OFDM (Orthogonal Frequency-Division Multiplexing), while Mobile WiMAX utilizes OFDMA (Orthogonal Frequency-Division Multiple Access). These technologies have been developed by IEEE and the standards are 802.16-2004, 802.16e-2005 and latest release is 802.16e-2009.

WiMAX operates across different RF bands, typically ranging from 3 to 3.6GHz, 2.3 to 2.4GHz, and 2.5 to 2.7GHz, depending on country-specific regulations. Manufacturers have developed RF equipment to support these diverse bands. Understanding the evolution of WiMAX within the IEEE standards is crucial to grasping its full capabilities.

WiMAX vs. WiFi: Coverage

WiMAX offers a significantly greater coverage area compared to WiFi (WLAN).

• WiFi Range: Approximately 30 meters.
• WiMAX Range: Up to 50 kilometers in radius.

WiMAX can theoretically support data rates of around 70Mbps using higher modulation schemes like QAM (Quadrature Amplitude Modulation).

WiMAX System Architecture

The diagram above illustrates the basic components of a WiMAX system:

• Base Station (BS): Connects to the internet backbone through an ASN-GW (Access Service Network Gateway).
• Subscriber Premises Equipment (SPE): Includes a modem and antenna.

The WiMAX subscriber modem connects either directly to a desktop computer or to a LAN (Local Area Network) or router. This allows for multiple devices (laptops, mobile phones, tablets) to simultaneously connect to the WiMAX data connection. In mobile WiMAX, user equipment like USB dongles, mobile phones, and tablets can directly connect to the base station for internet access.