Basic of Wireless

As we all know that with smartphones, tablets, and laptops taking over the world, the term wireless has become part of our everyday.A wireless local-area network (LAN) uses radio waves to connect devices such as laptops and mobile phones to the Internet and to our business network and its applications. When we connect to a Wi-Fi hotspot at a cafe, a hotel, an airport lounge, or another public place, we are connecting to that business's wireless network.Wireless technology is used in many types of communication. We use it for networking because it is cheaper and more flexible than running cables. 

Now the most important question which people will be assuming in wired the medium is cables/wires then in wireless what is the medium ?In wireless transmission, the medium used is the air, through electromagnetic, radio and microwave signals (we will be discussing about the radio signals in our next article).

Types of Wireless Network

Wireless PAN

Wireless personal area network (WPANs) connect devices within a relatively small area, that is generally within a person's reach.For example, both bluetooth radio and invisible infrared light provides a WPAN for interconnecting a headset to a laptop.

Wireless LAN

A wireless local area network (WLAN) links two or more devices over a short distance using a wireless distribution method, usually providing a connection through an access point for internet access.The use of spread-spectrum orOFDM technologies may allow users to move around within a local coverage area, and still remain connected to the network.

Wireless ad hoc network (Mesh Network)

A wireless ad hoc network, also known as a wireless mesh network (mesh network has the wireless uplink) or mobile ad hoc network (MANET), is a wireless network made up of radio nodes organized in a mesh topology

Wireless MAN

Wireless metropolitan area networks are a type of wireless network that connects several wireless LANs.WiMAX is a type of Wireless MAN (We have already discussed that in our previous article).

Wireless WAN

Wireless wide area networks are wireless networks that typically cover large areas, such as between neighboring towns and cities. These networks can be used to connect branch offices of business or as a public Internet access system. 

Cellular network

A cellular network or mobile network is a communication network where the last link is wireless. The network is distributed over land areas called cells, each served by at least one fixed-location transceiver, but more normally three cell sites or base transceiver stations. RF signals are transmitted by an individual phone and received by the base station, where they are then re-transmitted from the base station to another mobile phone.

Why Wireless and what are the benefits of a Wi-Fi wireless network?

The most obvious advantage of wireless networking is mobility. Wireless network users can connect to existing networks and are then allowed to roam freely. A mobile telephone user can drive miles in the course of a single conversation because the phone connects the user through cell towers. This is not the only one advantage lets discuss benefits of wireless:

Convenience : Access your network resources from any location within your wireless network's coverage area or from any Wi-Fi hotspot

Mobility : You're not tied to your desk, as you are with a wired connection, example: You and your employees can go online in conference room meetings,

Productivity : Wireless access to the Internet and to your company's key applications and resources helps your staff get the job done and encourages collaboration.

Easy setup : You don't have to string cables, so installation can be quick and cost effective.

Expandability : You can easily expand wireless networks with existing equipment, whereas a wired network might require additional wiring.

Security : Advances in wireless networks provide robust security protections.

Cost : Because wireless networks eliminate or reduce wiring expenses, they can cost less to operate than wired networks.

What is a Wi-Fi or wireless network vs. a wired network?

Early (pre 2008) networks were predominately wired..Today however most networks will use a mixture of wired and wireless network.

• One of the differences between 802.3 Ethernet and 802.11 wireless frames is the frame size.
• 802.3 frames have a maximum size of 1,518 bytes with a maximum data payload of 1,500 bytes
• If the 802.3 frames are 802.1Q tagged for VLANs and user priority, the maximum

size of the 802.3 frame is 1,522 bytes with a data payload of 1,504 bytes.

• 802.11 frames are capable of transporting frames with an MSDU (MAC Protocol Data Unit, we will discuss this in the next article) payload of 2,304 bytes of upper layer data.
• MAC addressing used by 802.11 frames is much more complex than Ethernet frames.
• 802.3 frames have only a source address (SA) and destination address (DA) in the layer 2 header.
• 802.11 frames have up to four address fields in the MAC header.
• 802.11 frames typically use only three of the MAC address fields (4 in WDS environment).

802.11 frame format

• Frame Control: Indicates the type of frame (control, management, or data) and provides control information. Control information includes whether the frame is to or from a DS, fragmentation information, and privacy information.
• Duration/Connection ID: If used as a duration field, indicates the time (in microseconds) the channel will be allocated for successful transmission of a MAC frame. In some control frames, this field contains an association, or connection, identifier.
• Sequence Control: Contains a 4-bit fragment number subfield, used for frag- mentation and reassembly, and a 12-bit sequence number used to number frames sent between a given transmitter and receiver.
• Frame Body: Contains an MSDU or a fragment of an MSDU. The MSDU is a LLC protocol data unit or MAC control information.
• Frame Check Sequence: A 32-bit cyclic redundancy check.All packets or frames within a network can be damaged by crosstalk or interference in the network's physical wires. The frame check sequence (FCS) is an extra field in each transmitted frame that can be analyzed to determine if errors have occurred. The FCS uses cyclic redundancy checks (CRCs), checksums, and two-dimensional parity bits to detect errors in the transmitted frames.
• Address : The number and meaning of the 48-bit address fields depend on context. The transmitter address and receiver address are the MAC addresses of stations joined to the BSS (Basic Service Set is a component of the IEEE 802.11 WLAN architecture. ... When one access points (AP) is connected to wired network and a set of wireless stations it is referred to as a Basic Service Set )that are transmitting and receiving frames over the wireless LAN. The service set ID (SSID) identifies the wireless LAN over which a frame is transmitted. For an IBSS (Independent BSS) , the SSID is a random number generated at the time the network is formed. For a wireless LAN that is part of a larger configuration the SSID identifies the BSS over which the frame is transmitted; specifically, the SSID is the MAC-level address of the AP for this BSS (Figure 17.4). Finally the source address and destination address are the MAC addresses of stations, wireless or otherwise, that are the ultimate source and destination of this frame. The source address may be identical to the transmitter address and the destination address may be identical to the receiver address.
• Source Address (SA) The MAC address of the original sending station is known as the SA. The source address can originate from either a wireless station or the wired network.
• Destination Address (DA) The MAC address that is the final destination of the layer 2 frame is known as the DA. The final destination may be a wireless station or could be a destination on the wired network such as a server or a router.
• Transmitter Address (TA) The MAC address of an 802.11 radio that is transmitting the frame onto the half-duplex 802.11medium is known as the TA.
• Receiver Address (RA) The MAC address of the 802.11 radio that is intended to receive the incoming transmission from the transmitting station is known as the RA.

Advantages of a Wireless Network over Wired

The main advantage of a wireless network over a wired one is that users can move around freely within the area of the network with their laptops, handheld devices etc and get an internet connection.

Users are also able to share files and other resources with other devices that are connected to the network without having to be cabled to a port.

Not having to lay lots of cables and put them through walls etc. can be a considerable advantage in terms of time and expense. It also makes it easier to add extra devices to the network, as no new cabling is needed.

If you are a business such as a café, having a wireless network that is accessible to customers can bring you extra business. Customers generally love wireless networks because they are convenient.

Wireless networks can sometimes handle a larger amount of users because they are not limited by a specific number of connection ports.

Instant transfer of information to social media is made much easier. For instance, taking a photograph and uploading it to Facebook can generally be done much quicker with wireless technology.

Disadvantages of a Wireless Network

The general speed of a wireless connection is also usually much slower than a wired one. The connection also gets worse the farther you are from the router, which can be a problem in a large building or space.

Wireless connections can be obstructed by everyday household items and structures such as walls, ceilings, and furniture.

Wireless networks are generally less secure. There can also be problems with neighbors stealing bandwidth, if the network hasn’t been set up to be password protected. Information is also less secure too and can be easier to hack into.

File-sharing transfer speeds are normally slower with wireless networks than they are with cabled. The speeds can also vary considerably according to your location in relation to the network.