CWNA Guide to Wireless LANs, Second Edition Chapter Two Wireless LAN Devices and Standards

CWNA Guide to Wireless LANs, Second Edition2 Objectives List WLAN devices and describe their basic functions Explain the different types of communication standards and why standards are important List the three major wireless standards and regulatory agencies and their functions Describe the different IEEE WLAN standards

CWNA Guide to Wireless LANs, Second Edition3 WLAN Devices: Wireless Network Interface Card Network interface card (NIC): Connects computer to network so that it can send and receive data Wireless NICs perform same function, but without wires When wireless NICs transmit: –Change computer’s internal data from parallel to serial transmission –Divide data into packets and attach sending and receiving computer’s address –Determine when to send packet –Transmit packet

CWNA Guide to Wireless LANs, Second Edition4 WLAN Devices: Wireless Network Interface Card (continued) Figure 2-1: Network interface card for a wired network

CWNA Guide to Wireless LANs, Second Edition5 WLAN Devices: Wireless Network Interface Card (continued) Figure 2-2: Wireless NICs for desktop computers: (a) PCI network interface card, (b) standalone USB device, (c) USB key fob

CWNA Guide to Wireless LANs, Second Edition6 WLAN Devices: Wireless Network Interface Card (continued) Figure 2-3: Wireless NICs for laptop computers: (a) CardBus card; (b) Mini PCI card

CWNA Guide to Wireless LANs, Second Edition7 WLAN Devices: Wireless Network Interface Card (continued) For smaller devices, several options: –CardBus or Type II PC Card May require a sled –CompactFlash (CF) card: Consists of small circuit board containing flash memory chips and dedicated controller chip Small and consume little power –SDIO (Secure Digital I/O) or SDIO NOW! Card: Provides high-speed data input/output with low power consumption

CWNA Guide to Wireless LANs, Second Edition8 WLAN Devices: Wireless Network Interface Card (continued) A movement towards integrating wireless NICs –Would eliminate need for external wireless NICs Software drivers necessary to allow wireless NIC and operating system (OS) to interface –Windows XP and PDA OSs have built-in drivers

CWNA Guide to Wireless LANs, Second Edition9 WLAN Devices: Access Point Three major parts: –Antenna and radio transmitter/receiver –RJ-45 wired network interface –Special bridging software To interface wireless devices to other devices Two basic function: –Base station for wireless network –Bridge between wireless and wired networks

CWNA Guide to Wireless LANs, Second Edition10 WLAN Devices: Access Point (continued) Figure 2-6: An access point acts as a bridge between the wireless network and a wired network

CWNA Guide to Wireless LANs, Second Edition11 WLAN Devices: Access Point (continued) Range depends on several factors: –Type of wireless network supported –Walls, doors, and other solid objects Number of wireless clients that single AP can support varies: –Theoretically over 100 clients –No more than 50 for light network use –No more than 20 for heavy network use Power over Ethernet (PoE): Power delivered to AP through unused wires in standard unshielded twisted pair (UTP) Ethernet cable

CWNA Guide to Wireless LANs, Second Edition12 WLAN Devices: Remote Wireless Bridge Bridge: Connects two network segments together –Even if they use different types of physical media Remote wireless bridge: Connects two or more wired or wireless networks together –Transmit at higher power than WLAN APs –Use directional antennas to focus transmission in single direction –Delay spread: Minimize spread of signal so that it can reach farther distances –Have software enabling selection of clearest transmission channel and avoidance of noise and interference

CWNA Guide to Wireless LANs, Second Edition13 WLAN Devices: Remote Wireless Bridge (continued) Figure 2-8: Point-to-point remote wireless bridge

CWNA Guide to Wireless LANs, Second Edition14 WLAN Devices: Remote Wireless Bridge (continued) Figure 2-9: Point-to-multipoint remote wireless bridge

CWNA Guide to Wireless LANs, Second Edition15 WLAN Devices: Remote Wireless Bridge (continued) Four modes: –Access point mode: Functions as standard AP –Root mode: Root bridge can only communicate with other bridges not in root mode –Non-root mode: Can only transmit to another bridge in root mode –Repeater mode: Extend distance between LAN segments Placed between two other bridges Distance between buildings using remote wireless bridges can be up to 18 miles at 11 Mbps or 25 miles transmitting 2 Mbps

CWNA Guide to Wireless LANs, Second Edition16 WLAN Devices: Remote Wireless Bridge (continued) Figure 2-10: Root and non-root modes

CWNA Guide to Wireless LANs, Second Edition17 WLAN Devices: Remote Wireless Bridge (continued) Figure 2-11: Repeater mode

CWNA Guide to Wireless LANs, Second Edition18 WLAN Devices: Wireless Gateway Combines wireless management and security in single appliance –Authentication –Encryption –Intrusion detection and malicious program protection –Bandwidth management –Centralized network management

CWNA Guide to Wireless LANs, Second Edition19 Understanding Standards Standards make it easier to purchase and use wide variety of products Wireless technology based on standards –Standards help ensure different products from different vendors function in same capacity

CWNA Guide to Wireless LANs, Second Edition20 The Need for Standards Standards for telecommunications have been essential since very beginning –Without standards telecommunications would essentially be impossible Some IT professionals believe that standards have stifled growth in the field –Waiting for standards to catch up to changes slows down process of change and development In reality, standards have proven to be more beneficial than harmful

CWNA Guide to Wireless LANs, Second Edition21 Advantages and Disadvantages of Standards Table 2-1: Advantages and disadvantages of standards

CWNA Guide to Wireless LANs, Second Edition22 Types of Standards De facto standards: Common practices that the industry follows for various reasons –Ranging from ease of use to tradition to what majority of users do –Usually established by success in marketplace De jure standards: Official standards –Controlled by organization or body that has been entrusted with that task –Process for creating these standards can be very involved

CWNA Guide to Wireless LANs, Second Edition23 Types of Standards (continued) One complaint against de jure standards is amount of time it takes for a standard to be completed Consortia: Usually industry-sponsored organizations that want to promote a specific technology –Goal is to develop a standard that promotes organization’s specific technology in little time

CWNA Guide to Wireless LANs, Second Edition24 Enforcing Standards Marketplace itself enforces some standards –Standards created by consortia often regulated by marketplace De jure standards often enforced by outside regulatory agency –Ensure that participants adhere to prescribed standards –Must have power to enforce standards and effectively punish those who refuse to abide by them

CWNA Guide to Wireless LANs, Second Edition25 Wireless Standards Organizations and Regulatory Agencies Three primary standard-setting and regulatory bodies that play major role in wireless LAN technology –Institute of Electrical and Electronics Engineers (IEEE) –Wi-Fi Alliance –U.S. Federal Communications Commission (FCC)

CWNA Guide to Wireless LANs, Second Edition26 Institute of Electrical and Electronics Engineers (IEEE) Establishes standards for telecommunications –Also covers wide range of IT standards World’s largest technical professional society –37 Societies and Councils –Publish technically focused journals, magazines, and proceedings –Work on over 800 standards Best known for its work in establishing standards for computer networks –Project 802

CWNA Guide to Wireless LANs, Second Edition27 Institute of Electrical and Electronics Engineers (continued) Table 2-2: Current IEEE 802 committees

CWNA Guide to Wireless LANs, Second Edition28 Wi-Fi Alliance Wireless Ethernet Compatibility Alliance (WECA): Consortium of wireless equipment manufacturers and software providers formed to promote wireless network technology –Three goals: Encourage wireless manufacturers to use IEEE technologies Promote and market these technologies to consumers at home, and in small and large organizations Test and certify that wireless products adhere to the IEEE standards

CWNA Guide to Wireless LANs, Second Edition29 Wi-Fi Alliance (continued) WECA changed name to Wi-Fi Alliance in 2002 –Reflected name of certification that it uses (Wi-Fi) to verify that products follow IEEE standards –Only products that pass Wi-Fi Alliance tests may be referred to as Wi-Fi Certified Wi-Fi Alliance now allows businesses to apply to be registered as a Wi-Fi ZONE –Qualifies them to be placed in online database of wireless hotspot locations Can be accessed through Alliance’s Web site

CWNA Guide to Wireless LANs, Second Edition30 Federal Communications Commission (FCC): Responsibilities Primary regulatory agency for wireless communications in U.S. and territorial possessions –Independent government agency –Directly responsible to Congress Broad range of responsibilities –Develop and implement regulatory programs –Process applications for licenses and other filings –Analyze complaints –Conduct investigations –Take part in congressional hearings

CWNA Guide to Wireless LANs, Second Edition31 FCC: Regulating the Radio Frequency Spectrum FCC regulates radio frequency spectrum –Entire range of all radio frequencies –Spectrum divided into 450 different bands –U.S. obligated to comply with international spectrum allocations FCC license normally required to send and receive on a specific frequency –License-exempt spectrum or unregulated bands: Bands that are available nationwide to all users –Created to foster development of new devices

CWNA Guide to Wireless LANs, Second Edition32 FCC: Regulating the Radio Frequency Spectrum (continued) Table 2-3: Common radio frequency bands

CWNA Guide to Wireless LANs, Second Edition33 FCC: Regulating the Radio Frequency Spectrum (continued) Two unregulated bands used for WLANs Industrial, Scientific, and Medical (ISM) band Unlicensed National Information Infrastructure (U-NII) band: Intended for devices that provide short-range, high-speed wireless digital communications Negative features of unregulated bands: –Devices from different vendors may attempt to use same frequency Can cause interference and unpredictability

CWNA Guide to Wireless LANs, Second Edition34 FCC: Regulating the Radio Frequency Spectrum (continued) Table 2-4: Unlicensed bands

CWNA Guide to Wireless LANs, Second Edition35 Types of Wireless LANs Since late 1990s, IEEE has approved four standards for wireless LANs: –IEEE –IEEE b –IEEE a –IEEE g IEEE n expected to be approved by 2006

CWNA Guide to Wireless LANs, Second Edition36 IEEE Specified that wireless transmission could take place via infrared (IR) or radio signals Infrared Transmissions: –Can send data by the intensity of the infrared light wave –Light spectrum: All types of light –Infrared light: Can be used for wireless transmissions Invisible –Emitter: Device that transmits a signal –Detector: Device that receives a signal

CWNA Guide to Wireless LANs, Second Edition37 IEEE (continued) Figure 2-13: Directed transmission

CWNA Guide to Wireless LANs, Second Edition38 IEEE (continued) Figure 2-14: Diffused transmission

CWNA Guide to Wireless LANs, Second Edition39 IEEE (continued) Infrared Transmissions (continued): –Advantages: Does not interfere with other communications signals Not affected by other signals Does not penetrate walls –Disadvantages: Lack of mobility Limited range Confined to indoor use Slow transmission speed

CWNA Guide to Wireless LANs, Second Edition40 IEEE (continued) Radio Wave Transmissions: –Radio waves can penetrate through objects Provides mobility –Radio waves travel longer distances –Can be used indoors and outdoors –Radio waves can travel at much higher speeds than infrared transmissions –IEEE standard outlining radio wave transmissions has become preferred method for wireless LANs

CWNA Guide to Wireless LANs, Second Edition41 IEEE b standard’s 2 Mbps bandwidth not sufficient for most network applications b amendment added two higher speeds (5.5 Mbps and 11 Mbps) to original standard –Uses ISM band Supports wireless devices up to 115 meters (375 feet) apart –Radio waves decrease in power over distance –802.11b standard specifies that, when devices out of range to transmit at 11 Mbps, devices drop transmission speed to 5.5 Mbps

CWNA Guide to Wireless LANs, Second Edition42 IEEE a IEEE a standard specifies maximum rated speed of 54 Mbps –Also supports 48, 36, 24, 18, 12, 9,and 6 Mbps transmissions using U-NII band a and b published at same time –802.11a came to market later due to technical issues and high production cost Range of a is less than that of b

CWNA Guide to Wireless LANs, Second Edition43 IEEE g Effort to combine best features of a and b –Data transfer rates to 54 Mbps –Support devices up to 115 meters apart g standard specifies that devices operate entirely in ISM frequency

CWNA Guide to Wireless LANs, Second Edition44 Projected IEEE n Currently in evaluation stage Top speed of n standard will be anywhere from 100 Mbps to 500 Mbps Ratification may not occur until 2006 –Devices based on standard may appear prior to that pre-N

CWNA Guide to Wireless LANs, Second Edition45 Summary Wireless LAN devices are in many respects similar to those found in a wired network; the main difference is that wireless devices use an antenna or other means to send and receive signals instead of a wired connection An access point (AP) is both the base station for the wireless network and a bridge to connect the wireless network with the wired network A remote wireless bridge is a wireless device designed to connect two or more wired or wireless networks together

CWNA Guide to Wireless LANs, Second Edition46 Summary (continued) Standards ensure that devices from one vendor will interoperate with those from other vendors, and create competition between vendors There are three regulatory bodies that play a major role in wireless LAN technology: the IEEE, the Wi- Fi Alliance, and the FCC There currently are three standards or types of wireless LANs: IEEE b, IEEE a, and IEEE g