WIRELESS NETWORKS

What is Wireless Network????

Wireless network refer to any type of computer network that is not connected by cables of any kind. It is a method by which telecommunications networks and enterprise (business), installations avoid the costly process of introducing cables into to a building, or as a connection between various equipment locations. Wireless telecommunications networks are generally implemented and administered using a transmission system called radio waves. This implementation takes place at the physical level, (layer), of the network structure.


Wireless network is a network set up by using radio signal frequency to communicate among computers and other network devices. Sometimes it’s also referred to as WiFi network or WLAN. This network is getting popular nowadays due to easy to setup feature and no cabling involved. You can connect computers anywhere in your home without the need for wires.

Here is simple explanation of how it works, let say you have 2 computers each equipped with wireless adapter and you have set up wireless router. When the computer send out the data, the binary data will be encoded to radio frequency and transmitted via wireless router. The receiving computer will then decode the signal back to binary data.

It doesn’t matter you are using broadband cable/DSL modem to access internet, both ways will work with wireless network. If you heard about wireless hotspot, that means that location is equipped with wireless devices for you and others to join the network.


The two main components are wireless router or access point and wireless clients :

If you have not set up any wired network, then just get a wireless router and attach it to cable/DSL modem. You then set up wireless client by adding wireless card to each computer and form a simple wireless network. You can also cable connect computer directly to router if there are switch ports available.

Wireless router or access points should be installed in a way that maximizes coverage as well as throughput. The coverage provided is generally referred to as the coverage cell. Large areas usually require more than one access point in order to have adequate coverage. You can also add access point to your existing wireless router to improve coverage.




Wireless Operating Mode

The IEEE 802.11 standards specify two operating modes: infrastructure mode and ad hoc mode.

Infrastructure mode is used to connect computers with wireless network adapters, also known as wireless clients, to an existing wired network with the help from wireless router or access point. The 2 examples which I specified above operate in this mode.

Ad hoc mode is used to connect wireless clients directly together, without the need for a wireless router or access point. An ad hoc network consists of up to 9 wireless clients, which send their data directly to each other.





Types of wireless connections

Wireless PAN

Wireless Personal Area Networks (WPANs) interconnect devices within a relatively small area, generally within a persons reach. For example, both Bluetooth radio and invisible Infrared light provides a WPAN for interconnecting a headset to a laptop.Wi-Fi PANs are becoming commonplace (2010) as equipment designers start to integrate Wi-Fi into a variety of consumer electronic devices. Intel "My WiFi" and Windows 7 "virtual Wi-Fi" capabilities have made Wi-Fi PANs simpler and easier to set up and configure.

Wireless LAN

A wireless local area network (WLAN) links two or more devices using a wireless distribution method, providing a connection through an access point to the wider internet. The use of spread-spectrum or OFDM technologies also gives users the mobility to move around within a local coverage area, and still remain connected to the network.

Wi-Fi: "Wi-Fi" is a term used to describe 802.11 WLANs, although it is technically a declared standard of interoperability between 802.11 devices.

Fixed Wireless Data: This implements point to point links between computers or networks at two distant locations, often using dedicated microwave or modulated laser light beams over line of sight paths. It is often used in cities to connect networks in two or more buildings without installing a wired link.

Wireless MAN

Wireless Metropolitan Area Networks are a type of wireless network that connects several Wireless LANs.

WiMAX is a type of Wireless MAN and is described by the IEEE 802.16 standard.

Wireless WAN

Wireless wide area networks are wireless networks that typically cover large outdoor areas. These networks can be used to connect branch offices of business or as a public internet access system. They are usually deployed on the 2.4 GHz band. A typical system contains base station gateways, access points and wireless bridging relays. Other configurations are mesh systems where each access point acts as a relay also. When combined with renewable energy systems such as photo-voltaic solar panels or wind systems they can be stand alone systems.


Mobile devices networks


Global System for Mobile Communications (GSM): The GSM network is divided into three major systems: the switching system, the base station system, and the operation and support system. The cell phone connects to the base system station which then connects to the operation and support station; it then connects to the switching station where the call is transferred to where it needs to go. GSM is the most common standard and is used for a majority of cell phones.

Personal Communications Service (PCS): PCS is a radio band that can be used by mobile phones in North America and South Asia. Sprint happened to be the first service to set up a PCS.

D-AMPS: Digital Advanced Mobile Phone Service, an upgraded version of AMPS, is being phased out due to advancement in technology. The newer GSM networks are replacing the older system.


Uses:

Wireless networks continue to develop, usage has grown in 2010. Cellular phones are part of everyday wireless networks, allowing easy personal communications. Inter-continental network systems use radio satellites to communicate across the world. Emergency services such as the police utilize wireless networks to communicate effectively. Individuals and businesses use wireless networks to send and share data rapidly, whether it be in a small office building or across the world.

Another use for wireless networks is a cost effective means to connect to the Internet, in regions where the telecommunications infrastructure is both poor and lacking in resources, typically in rural areas and developing countries.

Compatibility issues also arise when dealing with wireless networks. Different devices may have compatibility issues, or might require modifications to solve these issues. Wireless networks are often typically slower than those found in modern versions of Ethernet cable connected installations.

A wireless network is more vulnerable, because anyone can intercept and sometimes divert a network broadcasting signal when point to point connections are used. Many wireless networks use WEP - Wired Equivalent Privacy - security systems. These have been found to be still vulnerable to intrusion. Though WEP does block some intruders, the security problems have caused some businesses to continue using wired networks until a more suitable security system can be introduced. The use of suitable firewalls overcome some security problems in wireless networks that are vulnerable to attempted unauthorized access.


Wireless Access Point vs. Ad Hoc Network

Some people confuse Wireless Access Points with Wireless Ad Hoc networks. An Ad Hoc network uses a connection between two or more devices without using a wireless access point: the devices communicate directly when in range. An Ad Hoc network is used in situations such as a quick data exchange or a multiplayer LAN game because setup is easy and does not require an access point. Due to its peer-to-peer layout, Ad Hoc connections are similar to Bluetooth ones and are generally not recommended for a permanent installation.

Internet access via Ad Hoc networks, using features like Windows' Internet Connection Sharing, may work well with a small number of devices that are close to each other, but Ad Hoc networks don't scale well. Internet traffic will converge to the nodes with direct internet connection, potentially congesting these nodes. For internet-enabled nodes, Access Points have a clear advantage, with the possibility of having multiple access points connected by a wired LAN.


Limitations of Wireless Access Point

One IEEE 802.11 WAP can typically communicate with 30 client systems located within a radius of 100 m.[citation needed] However, the actual range of communication can vary significantly, depending on such variables as indoor or outdoor placement, height above ground, nearby obstructions, other electronic devices that might actively interfere with the signal by broadcasting on the same frequency, type of antenna, the current weather, operating radio frequency, and the power output of devices. Network designers can extend the range of WAPs through the use of repeaters and reflectors, which can bounce or amplify radio signals that ordinarily would go un-received. In experimental conditions, wireless networking has operated over distances of several hundred kilometers.

Most jurisdictions have only a limited number of frequencies legally available for use by wireless networks. Usually, adjacent WAPs will use different frequencies (Channels) to communicate with their clients in order to avoid interference between the two nearby systems. Wireless devices can "listen" for data traffic on other frequencies, and can rapidly switch from one frequency to another to achieve better reception. However, the limited number of frequencies becomes problematic in crowded downtown areas with tall buildings using multiple WAPs. In such an environment, signal overlap becomes an issue causing interference, which results in signal droppage and data errors.

Wireless networking lags behind wired networking in terms of increasing bandwidth and throughput. While (as of 2010) typical wireless devices for the consumer market can reach speeds of 300 Mbit/s (megabits per second) (IEEE 802.11n) or 54 Mbit/s (IEEE 802.11g), wired hardware of similar cost reaches 1000 Mbit/s (Gigabit Ethernet). One impediment to increasing the speed of wireless communications comes from Wi-Fi's use of a shared communications medium, so a WAP is only able to use somewhat less than half the actual over-the-air rate for data throughput. Thus a typical 54 MBit/s wireless connection actually carries TCP/IP data at 20 to 25 Mbit/s. Users of legacy wired networks expect faster speeds, and people using wireless connections keenly want to see the wireless networks catch up.

By 2008 draft 802.11n based access points and client devices have already taken a fair share of the market place but with inherent problems integrating products from different vendors.