Wireless LAN Overview

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Questions and Answers

What is the primary function of a BSS Master in a wireless network?

The BSS Master, typically an access point, acts as a gateway between the wireless clients and the wired network.

How is a Basic Service Set (BSS) identified in a wireless network?

A BSS is identified by its Service Set Identifier (SSID), which is alphanumeric and case sensitive.

What is the difference between a BSS and an Extended Service Set (ESS)?

A BSS is a single access point with its clients, while an ESS consists of interconnected BSSs that share a common SSID.

What is the role of a Distribution System (DS) in an Extended Service Set?

The DS connects access points within an Extended Service Set to increase network coverage and enable roaming. Signup and view all the answers

Name and briefly describe an encryption method used in Wireless LANs.

WPA2 is an encryption method that provides strong security through AES (Advanced Encryption Standard) for wireless networks. Signup and view all the answers

What are typical applications of Wireless LANs (WLANs)?

WLANs are used for a range of applications including home networks, campus networks, and public hotspots in places like hotels and restaurants. Signup and view all the answers

What characteristics must the BSSs in an Extended Service Set share?

All BSSs in an ESS must share a common Service Set Identifier (SSID). Signup and view all the answers

What protocols are currently used for wireless distribution systems (WDS)?

Current wireless distribution systems are mainly based on WDS or MESH protocols. Signup and view all the answers

What is the main limitation of the 802.11 wireless LAN standard?

The 802.11 standard offers a bandwidth of only 2 Mbps, which is considered too slow and is now obsolete. Signup and view all the answers

Why is security considered a major concern in wireless LANs compared to wired LANs?

Wireless LANs communicate over a more open medium, making them more susceptible to unauthorized access and interference from other devices. Signup and view all the answers

What role do Access Points (APs) play in wireless networks?

Access Points create hotspot areas that allow systems with appropriate wireless adopters to access network services without physical connections. Signup and view all the answers

How does the bandwidth of the 802.11g standard compare to that of the 802.11b standard?

The 802.11g standard has a bandwidth of 54 Mbps, while the 802.11b standard provides only 11 Mbps. Signup and view all the answers

What is the main feature of WEP encryption in wireless networks?

WEP (Wired Equivalent Privacy) encryption aims to provide a level of security comparable to wired networks but is now considered weak and easily compromised. Signup and view all the answers

What distinguishes WPA2 encryption from WPA in wireless networking?

WPA2 encryption uses AES (Advanced Encryption Standard), providing stronger security than the TKIP (Temporal Key Integrity Protocol) used in WPA. Signup and view all the answers

How can existing WLAN infrastructures be utilized without hardware modifications?

Existing WLAN infrastructures can function as indoor positioning systems by utilizing their current setup without needing additional hardware changes. Signup and view all the answers

What are the performance characteristics of the 802.11a standard?

The 802.11a standard operates at a frequency of 5.0 GHz, providing a bandwidth of 54 Mbps, but has a high cost and short range. Signup and view all the answers

What is the purpose of the IEEE 802.11 specifications regarding collisions?

To minimize collisions between mobile units that are in range of a common access point but out of range of each other. Signup and view all the answers

Explain the function of the Service Set Identifier (SSID) in a wireless LAN.

The SSID identifies a particular 802.11 wireless LAN and is broadcasted by access points within range to allow client devices to associate with a network. Signup and view all the answers

How does the Basic Service Set Identifier (BSSID) differ from the SSID?

The BSSID uniquely identifies each Basic Service Set (BSS), while the SSID can be shared among multiple BSSs in an extended service set. Signup and view all the answers

Describe the significance of authentication in WLAN standards.

Authentication establishes the identity of stations to each other, ensuring that only authorized users access the network. Signup and view all the answers

What security mechanisms are incorporated in the 802.11 standards to ensure message privacy?

The standard provides for optional use of encryption to prevent the content of messages from being read by unauthorized recipients. Signup and view all the answers

Explain the role of re-association in a wireless network.

Re-association allows an established association between a mobile station and an access point to transfer to another access point as the station moves. Signup and view all the answers

What is the purpose of dis-association in WLAN protocols?

Dis-association serves as a notification that an existing association is terminated between a station and an access point. Signup and view all the answers

How does indoor positioning benefit from WLAN standards?

Indoor positioning uses the characteristics of WLAN signals, like SSIDs and signal strengths, to accurately find the location of devices within a building. Signup and view all the answers

What frequency band does Motorola's WLAN product utilize for microwave transmission?

18GHz frequency band Signup and view all the answers

Name two methods used in Spread Spectrum Transmission.

Frequency hopping and direct sequence modulation Signup and view all the answers

What is the purpose of the code transmitted with signals in Direct Sequence Modulation?

To identify the appropriate signal transmitted by the sender unit Signup and view all the answers

List the three types of infrared transmission methods.

Diffused, directed, and directed point-to-point Signup and view all the answers

What does ISM stand for in the context of frequency bands reserved for wireless devices?

Industrial, Scientific and Medical Signup and view all the answers

What are the two primary components of an IEEE 802.11 architecture?

WLAN Stations (STA) and Access Point (AP) Signup and view all the answers

What are the frequency ranges of the ISM band?

902-928 MHz, 2400-2483.5 MHz, and 5725-5850 MHz Signup and view all the answers

How does frequency hopping work in Spread Spectrum Transmission?

The signal jumps from one frequency to another within a given frequency range. Signup and view all the answers

What are the main challenges of using wireless LANs compared to wired LANs?

Wireless LANs face security risks and instability due to interference from other devices, unlike wired LANs that use dedicated physical connections. Signup and view all the answers

Why is the 802.11 standard now considered obsolete?

The 802.11 standard offers only 2 Mbps bandwidth, which is too slow compared to newer standards. Signup and view all the answers

How does the performance of the 802.11g standard incorporate features from previous standards?

The 802.11g standard combines features of both 802.11b and 802.11a while providing a bandwidth of 54 Mbps. Signup and view all the answers

What factors limit the range of the 802.11a standard?

The 802.11a standard operates at a 5.0 GHz frequency, which is easily obstructed, leading to a shorter range. Signup and view all the answers

In what way do Access Points (APs) contribute to the security concerns of wireless networks?

APs create hotspot areas that allow any device within range to access the network, increasing the risk of unauthorized access. Signup and view all the answers

What is the significance of the bandwidth figure reported for 802.11n, despite its standards not being finalized?

The reported 108 Mbps for 802.11n suggests future advancements in wireless LAN performance, anticipating increased capabilities. Signup and view all the answers

How do the characteristics of 802.16d and 802.16e differ in terms of application?

802.16d is known as fixed Wimax for long distances, while 802.16e is mobile Wimax, enabling wireless connectivity on the go. Signup and view all the answers

What are the implications of using Bluetooth standards within the wireless LAN framework?

Bluetooth standards (802.11 h & j) operate at 2.4 GHz with very short distances, suitable for handheld applications. Signup and view all the answers

What is the primary advantage of WLANs over traditional LANs?

WLANs allow users to move freely within a confined area while maintaining network connectivity. Signup and view all the answers

How does Wi-Fi relate to the IEEE 802.11 standards?

Wi-Fi is a term often used interchangeably with IEEE 802.11 technology, representing wireless local area networking standards. Signup and view all the answers

What technology does the WAP protocol suite aim to enable for wireless communication?

The WAP protocol suite enables global wireless communication across various technologies like GSM, GPRS, UMTS, and 3G. Signup and view all the answers

Describe the role of access points in a WLAN.

Access points act as central transmitters and receivers for WLAN radio signals, facilitating communication between devices and the network. Signup and view all the answers

What is the significance of CSMA/CA in the IEEE 802.11 protocols?

CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) is used to manage data transmissions and reduce the risk of collisions in WLANs. Signup and view all the answers

What differentiates infrared transmission from microwave transmission in WLAN technology?

Infrared transmission relies on line-of-sight communication and is limited to short distances, while microwave transmission can cover longer ranges and penetrate through obstacles. Signup and view all the answers

What challenge does wireless LAN security face compared to wired networks?

Wireless LANs are more susceptible to unauthorized access and eavesdropping because their signals are broadcasted over the air. Signup and view all the answers

What are the implications of WLAN architecture on network performance?

WLAN architecture, including the placement of access points and frequency use, directly impacts connectivity, coverage, and overall network efficiency. Signup and view all the answers

How does the Access Point (AP) function in relation to BSS Clients within a BSS?

The AP acts as a gateway, enabling communication between BSS Clients and the wired LAN, facilitating their interaction with each other. Signup and view all the answers

In what way does an Extended Service Set (ESS) enhance user mobility compared to a Basic Service Set (BSS)?

The ESS allows stations to move transparently between interlinked BSSs without disruption in connectivity, as they all share the same SSID. Signup and view all the answers

What is the significance of the Service Set Identifier (SSID) in managing wireless network access?

The SSID distinguishes a BSS and enables BSS Clients to identify and connect to their respective networks safely. Signup and view all the answers

Describe how a Distribution System (DS) aids in extending network coverage in an ESS.

A DS links multiple access points, facilitating roaming and maintaining connectivity as users move between different BSSs within the ESS. Signup and view all the answers

What challenge is addressed by the concept of an Extended Service Set in a wireless LAN?

The ESS addresses the need for integrated wireless access across multiple BSSs to provide broader coverage and improved throughput. Signup and view all the answers

How does the architecture of a wireless LAN influence the performance of applications such as streaming or gaming?

The performance is affected by the network topology, specifically the arrangement of APs in BSSs and ESSs, which dictates bandwidth and latency. Signup and view all the answers

Explain the implications of having a common SSID in interconnected BSSs within an Extended Service Set.

A common SSID allows devices within the ESS to connect and communicate as if part of a single wireless network, ensuring easier access and mobility. Signup and view all the answers

What protocols are commonly associated with wireless distribution systems in an ESS, and why are they important?

Protocols like WDS and MESH are vital as they facilitate communication between access points, enhancing the reliability and coverage of the wireless network. Signup and view all the answers

What key characteristic of TKIP in WPA enhances security compared to WEP?

TKIP uses a per-packet key, generating a new 128-bit key for each packet, preventing attacks that compromised WEP. Signup and view all the answers

Why should WEP be avoided when configuring wireless networks?

WEP is the oldest and least secure encryption method, having numerous known vulnerabilities. Signup and view all the answers

How do WPA and WPA2 achieve better data protection than WEP?

WPA and WPA2 utilize stronger encryption methods and dynamic key management, which enhance overall security. Signup and view all the answers

What is a critical vulnerability of WEP that WPA addresses?

WEP lacks a mechanism for dynamic key changes, which leaves it susceptible to key reuse attacks. Signup and view all the answers

What does the message integrity check in WPA prevent?

It prevents an attacker from capturing, altering, and resending data packets. Signup and view all the answers

How do WPA and WPA2 improve upon the limitations of WEP regarding encryption key management?

WPA and WPA2 dynamically generate encryption keys, while WEP relies on static keys. Signup and view all the answers

What does enabling encryption in a wireless network accomplish?

It scrambles the data traveling across the network, preventing unauthorized access. Signup and view all the answers

What are the implications of having all devices on a wireless network use the same encryption type?

This ensures compatibility and cohesive security procedures across the entire network. Signup and view all the answers

What distinguishes 802.16-2004 from 802.16e-2005 in terms of mobility?

802.16-2004, or fixed WiMAX, does not support mobility, while 802.16e-2005 introduces mobility features. Signup and view all the answers

In what way does WiMAX provide a business continuity plan?

WiMAX enables businesses to maintain Internet connectivity by offering a wireless alternative to fixed connections, reducing service outage risks. Signup and view all the answers

Identify the major quality of service (QoS) mechanism differences between Wi-Fi and WiMAX.

WiMAX uses a connection-based QoS mechanism with specific scheduling algorithms, while Wi-Fi utilizes a connectionless QoS similar to fixed Ethernet. Signup and view all the answers

What types of connectivity does WiMAX offer compared to traditional wired access?

WiMAX offers fixed and portable connectivity, providing users with wireless Internet access as an alternative to wired connections. Signup and view all the answers

What is a primary application of WiMAX in the realm of Internet access?

WiMAX connects Wi-Fi hotspots to the Internet, providing a wireless alternative for broadband access. Signup and view all the answers

How does WiMAX's use of spectrum differ from that of Wi-Fi?

WiMAX utilizes both licensed and unlicensed spectrum for long-range connections, while Wi-Fi exclusively uses unlicensed spectrum. Signup and view all the answers

Describe how WiMAX can be utilized for IPTV services.

WiMAX provides the necessary bandwidth for delivering IPTV services over a wireless network, supporting high-quality video streaming. Signup and view all the answers

What defines the 'last mile' broadband access in relation to WiMAX?

WiMAX offers a wireless solution for 'last mile' broadband access, bridging the gap between Internet networks and end users. Signup and view all the answers

Study Notes

Wireless LAN

Wireless LANs are similar to traditional LANs but use a wireless interface
WLANs are becoming popular due to small portable devices like PDAs
WLANs provide high-speed data communication in small areas (buildings, offices)
Users can move around while staying connected to the network
Wi-Fi is synonymous with IEEE 802.11 technology
Wi-Fi enabled devices (computers, video game consoles, phones, etc.) can connect to the internet
Access points are nodes on WLANs that act as central transmitters/receivers of WLAN radio signals
Home/small business access points are typically small, dedicated devices with built-in network adapter, antenna, and radio transmitter
WAP (Wireless Application Protocol) defines network architecture for content delivery over wireless networks
WAP implements protocols similar to HTTP, TCP, and SSL to enable global wireless communication across technologies like GSM, GPRS, UMTS, and 3G
IEEE 802.11 defines physical layer (PHY) and MAC (Media Access Control) layers, based on CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance)
This is different from Ethernet's CSMA/CD (Carrier Sense Multiple Access with Collision Detection)
802.11 aims to minimize collisions between mobile units in range of a common access point

IEEE 802.11 Layered Protocol Architecture

Association: Establishes initial link between station and access point
Re-association: Transfers established connection from one access point to another
Dis-association: Notifies termination of an existing association (from either station or access point)
Authentication: Verifies identity of stations to each other
Privacy: Used to prevent unauthorized access to messages (optional encryption)

Service Set Identifier (SSID)

Name identifying a particular 802.11 wireless LAN
Access points broadcast SSIDs for automatic or manual network selection
Can be up to 32 characters long (human readable, but not required)

Basic Service Set Identifier (BSSID)

Uniquely identifies a basic service set (BSS)
In an infrastructure BSS, the BSSID is the MAC address of the access point (WAP)
In an IBSS (Independent BSS), the BSSID is a generated 48-bit random address

Transmission Technology

Microwave: Uses low-power microwave radio signals at 18GHz frequency
Spread Spectrum: Uses frequency hopping and direct sequence modulation techniques
Infrared: Uses infrared light for transmission (diffused, directed, directed point-to-point)

WLAN Architecture

Components: WLAN Stations (STAs) and Access Points (APs)
WLAN Stations (STA): Connect to an access point to reach network resources. Identified by 48-bit data link control address
Access Point (AP): Connects WLAN stations to wired networks. Bridges frames between WLAN and wired networks. Identified by 48-bit data link control address.
Basic Service Set (BSS): The minimum BSS consists of two stations.
Independent Basic Service Set (IBSS): A BSS not connected to a base, also referred to as ad-hoc network or peer-to-peer network
Extended Service Set (ESS): Two or more BSSs interconnected (Distribution Systems or DS)

BSS Master & BSS Clients

BSS Master: The Access Point, connected to wired LAN to act as gateway between wireless and wired networks.
BSS Client: Wireless stations that connect to and use services from the BSS Master

WLAN Applications and Standards

WLANs are used in home networks, campuses, and mobile networks (like airplanes and trains)
Users can access the Internet via WLAN hotspots (restaurants, hotels)
Some hotspots offer public Wi-Fi with no access restriction, while others require registration or paid access
Different IEEE standards offer different frequencies, bandwidths, and performance attributes

WLAN Security

Security is important because it is more open than wired networks
Administrators and users should take precautions to prevent unauthorized access
Configure encryption (WEP, WPA, WPA2) and MAC filtering to protect data
Use strong passwords as well as appropriate security measures when using public access point
Disable DHCP to prevent unauthorized access given IP address dynamically

Wi-MAX (Worldwide Interoperability for Microwave Access)

Technology for long-range wireless data transmission (miles/kilometers)
Designed for both point-to-multipoint and portable/mobile internet access
Based on the IEEE 802.16 standard
Suitable for applications like connecting Wi-Fi hotspots, providing alternative to cable/DSL, and providing data/telecommunication services

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Description

This quiz covers the fundamentals of Wireless LANs, exploring how they compare to traditional wired networks. It also discusses the significance of Wi-Fi technology, the roles of access points, and the importance of WAP in wireless communication. Test your understanding of these concepts and their applications in today's portable device-driven world.