Networking Part 8: Signals, Frequencies, & Interference

January 3, 2019 | Views: 6110

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Frequencies, Interference, Signal Strength, Bounce, Channel Bonding

Frequency Bands & channels

A frequency band is a range of frequency that is divided into multiple channels

Frequency bands are most commonly found as 2.4 GHz and 5GHz. When you change from channel 1 to 5, you gradually increase the wave of frequencies you’re sending information on.
2.4GHz Channel 1 à 2.412 GHz
2.4GHz Channel 6 à 2.437 GHz

Countries apply their own regulations to the allowable channels, allowing users and maximum power levels. When transmitting data on a channel, you usually overlap an environment of 2 channels around it. So if you were transmitting on channel 3, you would overlap 1 & 2 and 4 & 5. This is why it is important to always use the channels that you know don’t have a lot of interference. Routers usually talk together and agree on which channel to use when you connect.

2.4 GHz

  • Because slower wave passes easier through objects and goes further
  • More interference because of more devices on it
  • 14 channels (12,13,14 closed for government use)
  • Channel 1, 6, 11 most preferred because of the interference problem
  • Each channel is 22 MHz wide

5.0 GHz (→ 6 GHz)

  • Because faster waves, can’t reach as far
  • More data per each wave
  • More expensive
  • More channels, but more restrictions
  • Can cause interference with radar systems

Channel bonding

Bonds different channels together

Channel bonding is a practice commonly used in the IEEE 802.11 implementations. It has become very useful for achieving greater Wi-Fi data capacity. Several things similar to be mentioned that has the same concept within Link Aggregation are NIC bonding and Ethernet bonding.

Channel bonding = channel 1→ 8 all merged together (for example)
>Push through more data at the same time
>Less interference

Interference

If the connection comes and drops, there’s probably interference
Interference is anything which modifies or disrupts a signal when it travels. This is also referred to as Electromagnetic interference (EMI) or Co-channel interference (CCI).

Interference can be anything from Microwaves, phones, metal walls, baby radios, other Wireless Access Points or even weather conditions that disrupt the signal.

How to decrease interference:

  • change frequency
  • Change to another device
  • move closer to access points
  • move Access points higher up and center
  • get a different antenna. Omnidirectional antennas most preferred
  • increase power gain
  • 2.4 GHz à move to 5GHz because it’s a less crowded frequency band
  • check for interference with special software
  • adding additional access points
  • wireless networks talking together on the same channel instead of overlapping

Signal going in/out or video stutters over again or delay is a sign on interference

Signal strength

The power/data capacity of our signal

Signal strength is the power or amplitude of a signal that is being sent. Desired signal strength for optimal performance varies based on many factors, such as a number of users, desired data rate, which applications being used and the range of the signal. Signal strength is usually measured in decibels (dB) and should stay between -30 dB and -70 dB, depending on what it is required for.

How to increase the signal strength:

  • You can modify signal strength manually and turn the gain up/down
  • Always test boundaries with range software (to find out how much the signal covers of a geographical area)
  • Decrease distance between us and access point
  • Use Unidirectional antennas to push signal right at us
  • Use 2.4GHz to allow us to push the signal further

Bounce

When signal bounces off of an object and parts of signals reflect out
A signal bounce occurs when a signal is being transmitted and hits an object that mirrors it to other directions and devices by coincidence. This could be a WAP that sends radio signals onto a metal door and the signal is reflected back and collides with other signals, creating interference with the flow. This is highly unwanted since the data we are trying to push through bounces away and gets lost.

How to decrease signal bouncing:

  • Move WAP further up against the ceiling
  • Increase signal gain so it can push through the object
  • Implement another WAP on the other side of the object that creates the bounce
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