Theoretical wireless rate and actual wireless rate

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The theoretical speed of each protocol can be referred to the following table:

Take the 5GHz wireless network of 802.11n and 802.11ac as the example:

  • 802.11n: The maximum theoretical rate is 600Mbps.
  • 802.11ac: The maximum theoretical rate is 6.93Gbps.

In fact, there has a certain difference between the actual wireless rate in daily use and 7the above theoretical rate, which is mainly caused by two main factors.

 

1. Link Rate (Negotiation Rate)

There has a negotiation rate between the wireless client and the Access Point. The following is the relation between theoretical rate and negotiation rate.

Negotiation Rate ≤Maximum Theoretical Rate

This rate represents the maximum theoretical rate that can be achieved between the wireless client and the Access Point. This rate is not a fixed value, but it is related to the following factors:

  • Physical interference during transmission

In the transmission process when the Access Point sends a wireless signal to the wireless client, interference which often comes from noise created by other wireless routers, cordless phones, baby monitors, etc. and obstructions which are physical obstacles like walls and trees or large metal objects such as a refrigerator, will greatly affect the range, strength and quality of a wireless signal. Accordingly, the negotiation rate will be correspondingly reduced.

  • Hardware specifications for Access point and wireless clients

The maximum wireless speed exists for each wireless device. If the maximum wireless rate supported by the AP or wireless client is low, the maximum negotiation rate between AP and client is correspondingly low.

In reality, the negotiation rate can reach the maximum within a few meters from the wireless router, which is the maximum theoretical rate mentioned above.

 

2. Actual wireless transmission loss

The actual wireless rate generally only reaches 75% of the negotiation rate between the client and the router, and can only reach 30% to 50% in an environment with large wireless interference. The factors that affect the actual wireless rate as follows:

  • Amount of users

The available bandwidth in the same wireless network is shared among all users. The more bandwidth other users occupy at the same time, the slower the actual rate of the remaining users gets.

  • Co-channel interference/Adjacent channel interference

In the same space, other Access Points emitting wireless signals with the same frequency or partially overlapping frequencies may affect your wireless performance.

  • Necessary loss of network communication

The following is a simplified OSI reference model:

Application layer

Transport layer

Network layer

Link layer

The data used by the user is application layer data, but the rest of the data in the network transmission is also essential. In addition, the control data and management data required for the coding mode used by 802.11 wireless technology also occupy a portion of the wireless bandwidth, resulting in a further reduction in available bandwidth.

Combine the above two main factors, the actual rate of the wireless client is about 75% of the maximum theoretical rate when the wireless environment has less interference or  hardware does support the high wireless rate. However, when the wireless interference is large or the hardware does not support the high wireless rate, the actual rate of the wireless client will be further reduced.

 

Summary:

Tested under environments with less wireless interference, right distance, and one single client, the actual rate of the 802.11 wireless client is roughly as follows:

 

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