Types of Wireless Network Explained with Standards

This tutorial explains Wireless Network types (WLANS, WPANS, WMANS and WWANS) and Wireless network terminology (Ad hoc mode, Infrastructure mode, BSS, ESS, BSA, SSID, WEP, EAP, WPA, WPA2, Infrared, Bluetooth, FHSS, DSSS, FHSS, OFDM, MIMO, RF, Omni directional, 802.11g, 802.11a and 802.11h ) in detail.

A wireless network enables people to communicate and access applications and information without wires. This provides freedom of movement and the ability to extend applications to different parts of a building, city, or nearly anywhere in the world. Wireless networks allow people to interact with e-mail or browse the Internet from a location that they prefer.

Many types of wireless communication systems exist, but a distinguishing attribute of a wireless network is that communication takes place between computer devices. These devices include personal digital assistants (PDAs), laptops, personal computers (PCs), servers, and printers. Computer devices have processors, memory, and a means of interfacing with a particular type of network. Traditional cell phones don't fall within the definition of a computer device; however, newer phones and even audio headsets are beginning to incorporate computing power and network adapters. Eventually, most electronics will offer wireless network connections.

As with networks based on wire, or optical fiber, wireless networks convey information between computer devices. The information can take the form of e-mail messages, web pages, database records, streaming video or voice. In most cases, wireless networks transfer data, such as e-mail messages and files, but advancements in the performance of wireless networks is enabling support for video and voice communications as well.

Types of Wireless Networks

WLANS: Wireless Local Area Networks

WLANS allow users in a local area, such as a university campus or library, to form a network or gain access to the internet. A temporary network can be formed by a small number of users without the need of an access point; given that they do not need access to network resources.

WPANS: Wireless Personal Area Networks

The two current technologies for wireless personal area networks are Infra Red (IR) and Bluetooth (IEEE 802.15). These will allow the connectivity of personal devices within an area of about 30 feet. However, IR requires a direct line of site and the range is less.

WMANS: Wireless Metropolitan Area Networks

This technology allows the connection of multiple networks in a metropolitan area such as different buildings in a city, which can be an alternative or backup to laying copper or fiber cabling.

WWANS: Wireless Wide Area Networks

These types of networks can be maintained over large areas, such as cities or countries, via multiple satellite systems or antenna sites looked after by an ISP. These types of systems are referred to as 2G (2nd Generation) systems.

Comparison of Wireless Network Types
TypeCoveragePerformanceStandardsApplications

Wireless PAN

Within reach of a person

Moderate

Wireless PAN Within reach of a person Moderate Bluetooth, IEEE 802.15, and IrDa Cable replacement for peripherals

Cable replacement for peripherals

Wireless LAN

Within a building or campus

High

IEEE 802.11, Wi-Fi, and HiperLAN

Mobile extension of wired networks

Wireless MAN

Within a city

High

Proprietary, IEEE 802.16, and WIMAX

Fixed wireless between homes and businesses and the Internet

Wireless WAN

Worldwide

Low

CDPD and Cellular 2G, 2.5G, and 3G

Mobile access to the Internet from outdoor areas

Wireless Networking

Wireless networking is the new face of networking. Wireless networking have been around for many years. Cell phones are also a type of wireless communication and are popular today for people talking to each other worldwide.
Wireless networking are not only less expensive than more traditional wired networking but also much easier to install. An important goal of this site is to provide you adequate knowledge for installing a wireless network and get certified in wireless networks as well as.

Wireless Networking

Perhaps you already useing wireless networking in your local coffee shop, at the airport, or in hotel lobbies, and you want to set up a small office or home network. You already know how great wireless networking is, so you want to enjoy the benefits where you live and work. It is truly transformational to one's lifestyle to decouple computing from the wires! If you are looking to set up a wireless network, you've come to the right place. We will show you the best way to set up wirless network easily. Many people are looking to find out how to use wireless networking at home.

In this wireless networking section we provides An Absolute Beginner's Guide in the perfect format for easily learning what you need to know to get up to speed with wireless network without wasting a lot of time.
The organization of this site, and the special elements that we have described in this section will help you get the information you need quickly, accurately, and with clarity. In this section you will find inspiration as well as practical information. we believe that Wireless networks is a modest technology that has the power to have a huge and positive impact. This is wonderful material, and it's lots of fun! So what are you waiting for? It's time to Go for wireless networking.

Wireless Basic

Radio Frequency Transmission Factors

Radio frequencies (RF) are generated by antennas that propagate the waves into the air.
Antennas fall under two different categories:

directional and omni-directional.

Directional antennas are commonly used in point-to-point configurations (connecting two distant buildings), and sometimes point-to-multipoint (connecting two WLANs).
An example of a directional antenna is a Yagi antenna: this antenna allows you to adjust the direction and focus of the signal to intensify your range/reach.

Omni-directional antennas are used in point-to-multipoint configurations, where they distribute the wireless signal to other computers or devices in your WLAN. An access point would use an omni-directional antenna. These antennas can also be used for point-to-point connections, but they lack the distance that directional antennas supply

Three main factors influence signal distortion:
  • Absorption Objects that absorb the RF waves, such as walls, ceilings, and floors
  • Scattering Objects that disperse the RF waves, such as rough plaster on a wall, carpet on the floor, or drop-down ceiling tiles
  • Reflection Objects that reflect the RF waves, such as metal and glass
Responsible body

The International Telecommunication Union-Radio Communication Sector (ITU-R) is responsible for managing the radio frequency (RF) spectrum and satellite orbits for wireless communications: its main purpose is to provide for cooperation and coexistence of standards and implementations across country boundaries.

Two standards bodies are primarily responsible for implementing WLANs:

  • IEEE defines the mechanical process of how WLANs are implemented in the 802.11 standards so that vendors can create compatible products.
  • The Wi-Fi Alliancebasically certifies companies by ensuring that their products follow the 802.11 standards, thus allowing customers to buy WLAN products from different vendors without having to be concerned about any compatibility issues.
Frequencies bands:

WLANs use three unlicensed bands:

  • 900 MHz Used by older cordless phones
  • 2.4 GHz Used by newer cordless phones, WLANs, Bluetooth, microwaves, and other devices
  • 5 GHz Used by the newest models of cordless phones and WLAN devices
  • 900 MHz and 2.4 GHz frequencies are referred to as the Industrial, Scientific, and Medical (ISM) bands.
  • 5 GHz frequency the Unlicensed National Information Infrastructure (UNII) band.
  • Unlicensed bands are still regulated by governments, which might define restrictions in their usage.

A hertz (Hz) is a unit of frequency that measures the change in a state or cycle in a wave (sound or radio) or alternating current (electricity) during 1 second.

Transmission Method

Direct Sequence Spread Spectrum (DSSS) uses one channel to send data across all frequencies within that channel. Complementary Code Keying (CCK) is a method for encoding transmissions for higher data rates, such as 5.5 and 11 Mbps, but it still allows backward compatibility with the original 802.11 standard, which supports only 1 and 2 Mbps speeds. 802.11b and 802.11g support this transmission method.

OFDM (Orthogonal Frequency Division Multiplexing) increases data rates by using a spread spectrum: modulation. 802.11a and 802.11g support this transmission method.

MIMO (Multiple Input Multiple Output) transmission, which uses DSSS and/or OFDM by spreading its signal across 14 overlapping channels at 5 MHz intervals. 802.11n uses it. Use of 802.11n requires multiple antennas.

WLAN Standards

Standards802.11a802.11b802.11g802.11n
Data Rate54 Mbps11 Mbps54 Mbps248 Mbps (with 2×2 antennas)
Throughput23 Mbps4.3 Mbps19 Mbps74 Mbps
Frequency5 GHz2.4 GHz2.4 GHz2.4 and/or 5 GHz
CompatibilityNoneWith 802.11g and the original 802.11With 802.11b802.11a, b, and g
Range (meters)35–12038–14038–14070–250
Number of Channels3Up to 23314
TransmissionOFDMDSSSDSSS/OFDMMIMO

Two 802.11 access modes can be used in a WLAN:

  • Ad hoc mode
  • Infrastructure mode

Ad hoc mode is based on the Independent Basic Service Set (IBSS). In IBSS, clients can set up connections directly to other clients without an intermediate AP. This allows you to set up peer-to-peer network connections and is sometimes used in a SOHO. The main problem with ad hoc mode is that it is difficult to secure since each device you need to connect to will require authentication. This problem, in turn, creates scalability issues.

Infrastructure mode was designed to deal with security and scalability issues. In infrastructure mode, wireless clients can communicate with each other, albeit via an AP. Two infrastructure mode implementations are in use:

  • Basic Service Set (BSS)
  • Extended Service Set (ESS)

In BSS mode, clients connect to an AP, which allows them to communicate with other clients or LANbased resources. The WLAN is identified by a single SSID; however, each AP requires a unique ID, called a Basic Service Set Identifier (BSSID), which is the MAC address of the AP’s wireless card. This mode is commonly used for wireless clients that don’t roam, such as PCs.

In ESS mode, two or more BSSs are interconnected to allow for larger roaming distances. To make this as transparent as possible to the clients, such as PDAs, laptops, or mobile phones, a single SSID is used among all of the APs. Each AP, however, will have a unique BSSID.

Coverage Areas

A WLAN coverage area includes the physical area in which the RF signal can be sent and received Two types of WLAN coverage’s are based on the two infrastructure mode implementations:

  • Basic Service Area (BSA)
  • Extended Service Area (ESA)

The terms BSS and BSA, and ESS and ESA, can be confusing. BSS and ESS refer to the building topology whereas BSA and ESA refer to the actual signal coverage

BSA With BSA, a single area called a cell is used to provide coverage for the WLAN clients and AP

ESA With ESA, multiple cells are used to provide for additional coverage over larger distances or to overcome areas that have or signal interference or degradation. When using ESA, remember that each cell should use a different radio channel.

How an end user client with a WLAN NIC accesses a LAN

  • To allow clients to find the AP easily, the AP periodically broadcasts beacons, announcing its (SSID) Service Set Identifier, data rates, and other WLAN information.
  • SSID is a naming scheme for WLANs to allow an administrator to group WLAN devices together.
  • To discover APs, clients will scan all channels and listen for the beacons from the AP(s). By default, the client will associate itself with the AP that has the strongest signal.
  • When the client associates itself with the AP, it sends the SSID, its MAC address, and any other security information that the AP might require based on the authentication method configured on the two devices.
  • Once connected, the client periodically monitors the signal strength of the AP to which it is connected.
  • If the signal strength becomes too low, the client will repeat the scanning process to discover an AP with a stronger signal. This process is commonly called roaming.
SSID and MAC Address Filtering

When implementing SSIDs, the AP and client must use the same SSID value to authenticate. By default, the access point broadcasts the SSID value, advertising its presence, basically allowing anyone access to the AP. Originally, to prevent rogue devices from accessing the AP, the administrator would turn off the SSID broadcast function on the AP, commonly called SSID cloaking. To allow a client to learn the SSID value of the AP, the client would send a null string value in the SSID field of the 802.11 frame and the AP would respond; of course, this defeats the security measure since through this query process, a rogue device could repeat the same process and learn the SSID value.

Therefore, the APs were commonly configured to filter traffic based on MAC addresses. The administrator would configure a list of MAC addresses in a security table on the AP, listing those devices allowed access; however, the problem with this solution is that MAC addresses can be seen in clear-text in the airwaves. A rogue device can easily sniff the airwaves, see the valid MAC addresses, and change its MAC address to match one of the valid ones.
This is called MAC address spoofing.

WEP

WEP (Wired Equivalent Privacy) was first security solutions for WLANs that employed encryption. WEP uses a static 64-bit key, where the key is 40 bits long, and a 24-bit initialization vector (IV) is used. IV is sent in clear-text. Because WEP uses RC4 as an encryption algorithm and the IV is sent in clear-text, WEP can be broken. To alleviate this problem, the key was extended to 104 bits with the IV value. However, either variation can easily be broken in minutes on laptops and computers produced today.

802.1x EAP

The Extensible Authentication Protocol (EAP) is a layer 2 process that allows a wireless client to authenticate to the network. There are two varieties of EAP: one for wireless and one for LAN connections, commonly called EAP over LAN (EAPoL).

One of the concerns in wireless is allowing a WLAN client to communicate to devices behind an AP. Three standards define this process: EAP, 802.1x, and Remote Authentication Dial In User Service (RADIUS). EAP defines a standard way of encapsulating authentication information, such as a username and password or a digital certificate that the AP can use to authenticate the user.802.1x and RADIUS define how to packetize the EAP information to move it across the network.

WPA

Wi-Fi Protected Access (WPA) was designed by the Wi-Fi Alliance as a temporary security solution to provide for the use of 802.1x and enhancements in the use of WEP until the 802.11i standard would be ratified. WPA can operate in two modes: personal and enterprise mode. Personal mode was designed for home or SOHO usage. A pre-shared key is used for authentication, requiring you to configure the same key on the clients and the AP. With this mode, no authentication server is necessary as it is in the official 802.1 x standards. Enterprise mode is meant for large companies, where an authentication server will centralize the authentication credentials of the clients.

WPA2

WPA2 is the IEEE 802.11i implementation from the Wi-Fi Alliance. Instead of using WEP, which uses the weak RC4 encryption algorithm, the much more secure Advanced Encryption Standard (AES)–counter mode CBC-MAC Protocol (CCMP) algorithm is used.

Infrared

Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of microwave radiation. The name means "below red" (from the Latin infra, "below"), red being the color of visible light of longest wavelength.

Bluetooth

Is an industrial specification for wireless personal area networks (PANs). Bluetooth provides a way to connect and exchange information between devices like personal digital assistants (PDAs), mobile phones, laptops, PCs, printers and digital cameras via a secure, low-cost, globally available short range radio frequency.

FHSS

Frequency-hopping spread spectrum is a spread-spectrum method of transmitting radio signals by rapidly switching a carrier among many frequency channels, using a pseudorandom sequence known to both transmitter and receiver. Spread-spectrum transmission offers these advantages over a fixed-frequency transmission:

  • Highly resistant to noise and interference.
  • Signals are difficult to intercept. A Frequency-Hop spread-spectrum signal sounds like a momentary noise burst or simply an increase in the background noise for short Frequency-Hop codes on any narrowband receiver except a Frequency-Hop spread-spectrum receiver using the exact same channel sequence as was used by the transmitter.
  • Transmissions can share a frequency band with many types of conventional transmissions with minimal interference. As a result, bandwidth can be utilized more efficiently.
DSSS

direct-sequence spread spectrum is a modulation technique where the transmitted signal takes up more bandwidth than the information signal that is being modulated, which is the reason that it is called spread spectrum. Direct Sequence Spread Spectrum (DSSS)uses one channel to send data across all frequencies within that channel. Complementary Code Keying (CCK) is a method for encoding transmissions for higher data rates, such as 5.5 and 11 Mbps, but it still allows backward compatibility with the original 802.11 standard, which supports only 1 and 2 Mbps speeds. 802.11b and 802.11g support this transmission method.

Comparison of DSSS and Frequency Hopped SS
DSSS
  • Flexible support of variable data rates
  • High capacity is possible with enhancements (interference cancellation, adaptive antenna, etc.)
  • Suffers from near-far effect
FHSS
  • Suitable for ad hoc networks (no near-far problem)
  • Robust to interference
  • Limited data rate
OFDM

Orthogonal frequency-division multiplexing, also called discrete multitone modulation (DMT), is a transmission technique based upon the idea of frequency-division multiplexing (FDM). OFDM (Orthogonal Frequency Division Multiplexing) increases data rates by using a spread spectrum: modulation. 802.11a and 802.11g support this transmission method.

  • Used in some wireless LAN applications, including WiMAX and IEEE 802.11a/g
  • Used in many communications systems such as: ADSL, Wireless LAN, Digital audio broadcasting.
MIMO (Multiple Input Multiple Output)

MIMO (Multiple Input Multiple Output) transmission, which uses DSSS and/or OFDM by spreading its signal across 14 overlapping channels at 5 MHz intervals. 802.11n uses it. Use of 802.11n requires multiple antennas.

802.11a802.11b802.11g802.11n
Data Rate54 Mbps11 Mbps54 Mbps248 Mbps (with 2×2 antennas)
Throughput23 Mbps4.3 Mbps19 Mbps74 Mbps
Frequency5 GHz2.4 GHz2.4 GHz2.4 and/or 5 GHz
CompatibilityNoneWith 802.11g and the original 802.11With 802.11b802.11a, b, and g
Range (meters)35–12038–14038–14070–250
Number of Channels3Up to 23314
TransmissionOFDMDSSSDSSS/OFDMMIMO
Radio Frequency Transmission Factors

Radio frequencies (RF) are generated by antennas that propagate the waves into the air. Antennas fall under two different categories:

  • Directional
  • Omni-directional

Directional Directional antennas are commonly used in point-to-point configurations (connecting two distant buildings), and sometimes point-to-multipoint (connecting two WLANs). An example of a directional antenna is a Yagi antenna: this antenna allows you to adjust the direction and focus of the signal to intensify your range/reach.

Omni-directional Omni-directional antennas are used in point-to-multipoint configurations, where they distribute the wireless signal to other computers or devices in your WLAN. An access point would use an omni-directional antenna. These antennas can also be used for point-to-point connections, but they lack the distance that directional antennas supply

Three main factors influence signal distortion:

  • Absorption Objects that absorb the RF waves, such as walls, ceilings, and floors
  • Scattering Objects that disperse the RF waves, such as rough plaster on a wall, carpet on the floor, or drop-down ceiling tiles
  • Reflection Objects that reflect the RF waves, such as metal and glass
Responsible body

The International Telecommunication Union-Radio Communication Sector (ITU-R) is responsible for managing the radio frequency (RF) spectrum and satellite orbits for wireless communications: its main purpose is to provide for cooperation and coexistence of standards and implementations across country boundaries.
Two standards bodies are primarily responsible for implementing WLANs:

  • The Institute of Electrical and Electronic Engineers (IEEE)
  • The Wi-Fi Alliance.

IEEE Defines the mechanical process of how WLANs are implemented in the 802.11 standards so that vendors can create compatible products.

The Wi-Fi Alliance Basically certifies companies by ensuring that their products follow the 802.11 standards, thus allowing customers to buy WLAN products from different vendors without having to be concerned about any compatibility issues.

Frequencies bands:

WLANs use three unlicensed bands:

  • 900 MHz Used by older cordless phones
  • 2.4 GHz Used by newer cordless phones, WLANs, Bluetooth, microwaves, and other devices
  • 5 GHz Used by the newest models of cordless phones and WLAN devices

900 MHz and 2.4 GHz frequencies are referred to as the Industrial, Scientific, and Medical (ISM) bands.

5 GHz frequency the Unlicensed National Information Infrastructure (UNII) band.

Unlicensed bands are still regulated by governments, which might define restrictions in their usage.

A hertz (Hz) is a unit of frequency that measures the change in a state or cycle in a wave (sound or radio) or alternating current (electricity) during 1 second.

802.11g

Suffers from the same interference as 802.11b in the already crowded 2.4 GHz range. Devices operating in this range include microwave ovens, Bluetooth devices, and cordless telephones. Since the 2.4 GHz band is heavily used, using the 5 GHz band gives 802.11a the advantage of less interference. However, this high carrier frequency also brings disadvantages. It restricts the use of 802.11a to almost line of sight, necessitating the use of more access points; it also means that 802.11a cannot penetrate as far as 802.11b since it is absorbed more readily, other things (such as power) being equal.

802.11a

Transmits radio signals in the frequency range above 5 GHz. This range is "regulated," meaning that 802.11a gear utilizes frequencies not used by other commercial wireless products like cordless phones. In contrast, 802.11b utilizes frequencies in the unregulated 2.4 GHz range and encounters much more radio interference from other devices.

IEEE 802.11a / IEEE 802.11h

This is also a physical layer enhancement. IEEE 802.11a provides significantly higher performance than 802.11b, at 54 Mbps. Unlike 802.11b, the 802.11a standard operates within the frequency range of 5.47 to 5.725 GHz and is not subject to the same interference from other commercial electronic products. This higher frequency band allows significantly higher speeds of communication over the 2.4 GHz range.

802.11g APs are backward compatible with 802.11b APs. This backward compatibility with 802.11b is handled through the MAC layer, not the physical layer. On the negative side, because 802.11g operates at the same frequency as 802.11b, it is subject to the same interferences from electronic devices such as cordless phones. Since the standard’s approval in June 2003, 802.11g products are gaining momentum and will most likely become as widespread as 802.11b products. Table II-1 displays basic 802.11b/a/g characteristics.

The common range of operation for 802.11b is 150 feet for a floor divided into individual offices by concrete or sheet-rock, about 300 feet in semi-open indoor spaces such as offices partitioned into individual workspaces, and about 1000 feet in large open indoor areas. Disadvantages of 802.11b include interference from electronic products such as cordless phones and microwave ovens.

Range

The layout of your building can reduce the range.

  • A lot of concrete walls can reduce your range.
  • The size of the antenna and the placement greatly affect the range of their signals
  • The weather and amount of water vapor in the air can affect your signals strength
Speed
  • The layout of your building can reduce the speed
  • The size of the antenna and its signal can affect your speed
  • The weather and amount of water vapor can weaken the signal and affect your speed

ComputerNetworkingNotes CCNA Study Guide Types of Wireless Network Explained with Standards