Wireless Session 2

Wireless Technology Overview - Study Guide

Session Objectives

This session covers the essential roles of WLAN and networking organizations, details on the IEEE standard creation process including working groups, naming conventions, drafts, and ratification. It also discusses WLAN topologies (IBSS, BSS, ESS) and the 802.11 medium access mechanisms important for wireless communication.

Wi-Fi-Related Organizations

Key organizations include:

  • IETF (Internet Engineering Task Force): Focused on improving Internet functionality through RFC documents, which detail contributors, standards, and previous versions.

  • Regulatory Bodies: Such as the FCC (USA) and IC (Canada) that regulate radio communications, certifying systems and establishing operation guidelines in their domains.

  • IEEE (Institute of Electrical and Electronics Engineers): Develops LAN and WAN standards, particularly the 802.11 standards for wireless LAN, addressing both the Data Link and Physical layers. It oversees a structured standards creation involving working groups and committees, progressing from drafts to ratified standards, utilizing specific nomenclature for standards (uppercase) and amendments (lowercase).

IEEE 802.11 Timeline

The original 802.11 standard emerged in 1997, followed by significant amendments:

  • 802.11a (1999): 5 GHz, data rates 6-54 Mbps, OFDM modulation.

  • 802.11b (1999): 2.4 GHz, backward compatible with DSSS, data rates 5.5 and 11 Mbps.

  • 802.11g (2003): 2.4 GHz, backward compatible with 802.11b, up to 54 Mbps.

  • 802.11n (2009): 2.4 & 5 GHz, backward compatible, up to 600 Mbps.

  • 802.11ac (2013): 5 GHz only, very high throughput, up to 6.93 Gbps.

Wi-Fi Alliance

Responsible for device certification and interoperability testing, the Wi-Fi Alliance’s Wi-Fi CERTIFIED™ label indicates successful device testing. Certifications span areas such as connectivity and security. They also oversee Power over Ethernet (PoE) standards (802.3).

IEEE 802.1X and EAP

IEEE 802.1X: A framework for authenticating devices on WLANs with three roles:

  • Supplicant: Requests authentication.

  • Authenticator: Grants access.

  • Authentication Server: Conducts authentication.

EAP (Extensible Authentication Protocol): Supports various authentication methods, including PEAP and EAP-TLS. RADIUS facilitates the transfer of user authentication information between servers, serving as an AAA protocol for authentication, authorization, and accounting.

Overview of WLAN Topologies

Three primary WLAN topologies:

  • IBSS: Peer-to-peer network with no access point.

  • BSS: Contains one access point and connected client stations covering a Basic Service Area (BSA).

  • ESS: A network of multiple BSS connected by a distribution system, allowing communication in an extended service area (ESA).

802.11 Medium Access Mechanisms

802.11 defines methods for managing data transfer using:

  • Data frames: encompassing data, control, and management.

  • Medium Access Control (MAC): Uses CSMA/CA to avoid collisions, utilizing concepts like physical and virtual carrier sense, backoff timers, and interframe spaces.

Summary of Key Concepts

  • Understand the WLAN topologies: IBSS, BSS, ESS.

  • Recognize the significance of IEEE standards and amendments, particularly in relation to 802.11.

  • Familiarize yourself with the medium access methods (CSMA/CA) employed in wireless networks to handle data traffic effectively.