Wireless Network allows to connect with your LAN network without wire over a Mobile, Laptop with seamless Roaming without any wire connectivity. It is LAN technology that is used to connect Home, Campus, Building, and Corporate networks. So Welcome to Kbrosis, Here we will share our knowledge and experience and understand Wireless Networks and How Wireless Networks Works. How Wireless Network Design and Implementation. What is WLC, Access Point in simple ways because our motive is to “Simplify the Technology”.
What is a Wireless Network?
Wi-Fi Stands for Wireless-Fidelity. Wi-Fi is a wireless technology that allows you to connect computers, tablets, smartphones, and other devices to the internet and Intranet.
Wi-Fi (Wireless-Fidelity) is a wireless network technology that allows computers and other devices to communicate over a wireless Signal. It is a LAN Wireless technology.
Wireless Network Types
WLAN ( IEEE 802.11)- High Performance ,used for LAN enterprise network.
PAN ( IEEE802.15)- Its Personal Lan network like Bluetooth. The range is short—about 20 feet. Unlicensed 2.4-GHz Spectrum
MAN ( IEEE 802.16)– It is Metropolitan-area network with speeds of 1 to 10 Mbps within a range of 4 to 10 kilometres.
WAN- Its Wide area network which use to connect Geographical area over mobile network.
CSMA/CA
IEEE Wi-Fi 802.11 technologies using CSMA-CA (Carrier Sens Multiple Access-Collision Avoidance) as Wireless Network can not detect the collision like Wire (CSMA/CD), Wireless only can avoid the collision.
Line of Sight
Clear Line of Sight between two RF is required for Good Signal Transmission.
FRESZENL ZONE
Fresznel is an French physicist who invent Fresznel zone–During Wi-Fi survey, it needs to be considered that Wi-Fi access area should be at least 60 percent clear of obstructions for Wireless Signals.
RSSI and SNR
RSSI stands for Received Signal Strength Indicator. RSSI is in Negative Value (in dbm) and closer to 0 is good. RSSI indicate that what is the strength of your Wi-Fi signal or SSID. Less than -55 dbm is better.
SNR stands for Signal to Noise Ratio. Higher SNR is better. SNR above 20 is Good. Wi-Fi signal effected with multiple obstacles and SNR is provide the details that how much Noise or disturbance your signal have.
BSA / CELL: Wireless clients are associated with an AP. In the wireless space, the coverage area of the AP is called a Basic Service Area (BSA), which is also sometimes known as a wireless cell.
Access Points : AP is the network wireless devices which is associate with WLC and broadcast wireless SSID to connect with Wireless Network.
AP Type: There are Two type of AP 1) Autonomous AP (2) Lightweight Access Point (LAP)
Autonomous Access Points: These Access points are works autonomously. They do not required any central management server to configure and Manage.
Lightweight Access Points: These Access Points are registered/associate with Wireless LAN Controller (WLC) and these are configure and Manage by WLC only.
SSID :
On the AP, the network is associated with a MAC address. This network or work group that your clients connect to is called a Service Set Identifier (SSID). So on an AP, the SSID is a combination of MAC address and network name.
MBSSID: When the AP has more than one network, it is called a Multiple Basic Service Set Identifier (MBSSID).
BEACON / PROBES :In Management Frame, beacon frame used to help clients find the network. Beacon Frame is hello packet between two AP / users. When the client hears the beacon frame, it can learn a great deal of information about the cell. A beacon frame also includes the SSIDs that the AP supports, the rates that are supported, and six fields called Parameter Set that indicate modulation methods and such. The AP sends beacons every 2 seconds.
Wireless Obstacles
There are multiple obstacles which can impact Wireless Signal Strength, i.e. Microwaves, Bricks wall, Glass door and walls, Wooden walls, high volume Music and multiple Wireless SSID.
When we conduct per-implementation ( active or Passive Survey) we need to take care of the Access Point location to avoid all this obstructions.
Channel and Overlapping issues
There are 23 non=overlapping channel for 5 Ghz and 3 for 2.4 Ghz ( 1, 6, 11). Let’s understand how this channel works?
Above mentioned example is for 2.4 GHz. Here you can see there are 14 channel showing.. but if we see channel 1, 6 and 11 are not overlapping with channel 6 and 11. same for other channels.. I means any 3 channel you can configure for 2.4 which should not be overlap with each other.
Now let’s understand with an example that why these non-overlapping Channel are required?
The non-overlapping channels are deployment with three or more adjacent access points. This will minimize the interference between each of the access points with their respective BSA / Cell and provide sufficient space to user to get maximum transmission signal also its allows to mobile devices associated with those access points quickly.
If two adjacent Cell have same Channel ( example both Cell have Ch-1) then they overlapped to each other and mobile device also got confused that to which access points they need to connect. In this case user will face connect, Disconnect, low signal, Bandwidth issues etc.
AP in Different Channel for Roaming
In a big campus or organization there are multiple floors and building with Large numbers of access points are implemented to provide Network access over Wireless Network.
So, if User roaming between one building to another or one floor to another or one room to another, then once user will go out of Wi-Fi cell user will get disconnected then connect again with different AP / Cell, then it will repeat again and again. This is not acceptable at all !.
Here there are 3 access points with Ch-1, 6 and 11 and these are overlapping with each other. Here you will say that, “ but these channel should not be overlapped and 1,6,11 are non-overlapping channel”. You are right they should not be.
But, here we need to remember that to provide seamless Roaming to user we have to design the Wireless Network with these Channel overlapped min 20%. But Why?
See, These are all 3 Access points are in non-overlapping Channel and if user are in respective AP cell coverage then user will not face any connection issue, but if user will go / Move or roaming from CH-1 to CH-2 or we can consider AP -1 as Floor one and AP-2 as floor-2 then user will not get disconnect as user is in min 20% coverage area from AP-1 to AP-2 Cell.
Seamless Roaming.
Once, User will out of AP-1 coverage, Mobile device will get connected with AP-2 without any disconnection because when Mobile device losing the signal Strength from AP-1, during the same time it will getting better strength from AP-2 and during this roaming with min 20% overlap coverage mobile device get time to disconnect with Ap-1 and get connected with AP-2 without any disconnection, This is called Seamless Roaming.
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