Difference between Single-, Dual-, and Tri-Band Routers

Communication

Unless you’re a CS or ICT major (and sometimes even then), when you set out to buy a new router, you can find yourself frustratingly overwhelmed pretty quickly. That’s because new devices, including routers, always come with confusing labels, letters, and numbers that seem like they should convey a lot of information but really… don’t. At least until now! We offer you a guide to understanding router jargon. If you’ve heard the phrases “dual-band” or “tri-band” but didn’t know what they meant, we’re here to help you make sense of it all.

Some background on wireless transmission

First, a little bit of background on how the wireless transmission of information works. In order to transmit information wirelessly, we need a transmitter and a receiver. The first receives the information in its original form (like sound or video) and imprints it on an electromagnetic wave – called the carrier. This process is called modulation. The resulting wave carries all the information over to the receiver, which deconstructs it back to a carrier wave and original information (demodulation). 

 

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Any electromagnetic wave (including carrier waves) has a specific frequency at which it oscillates. This represents the number of cycles passing a given point per second and it is measured in Hertz (Hz).


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What does this have to do with routers?

In the case of wireless routers there are 2 frequency bands that are transmitted: 2.4 GHz (GigaHertz) and 5 GHz. Single-band routers transmit only over the 2.4 GHz frequency band, dual-band routers transmit over one 2.4 GHz band and one 5 GHz band, and tri-band routers transmit one 2.4 GHz band and two 5 GHz bands. These frequencies aren’t transmitted at precisely 2.4 GHz or 5 GHz, but are actually ranges (2.4-2.5 GHz and 5.725-5.875 GHz). Within the range, there are channels (22 MHz wide in 2.4 and 20 MHz wide in 5) over which devices transmit information. 

 

Photo by Michael Gauthier, Wireless Networking in the Developing World © Attribution-Share Alike 3.0 Unported



Many other household devices use the 2.4 GHz band such as cordless phones, Bluetooth, microwave ovens, baby monitors, and car alarm sensors.

So, the 5 GHz band is definitely better?

Well… It might seem that way because of its greater frequency (more of the wave passes per second), but that doesn’t mean it carries more information in that time. The reason for that is the frequency of modulation is almost equal on both frequencies. This makes the rate of transmission of information about the same The 5 GHz band is faster for a number of reasons:

  • Its range is wider: 0.150 GHz vs. 0.100 in 2.4.
  • There are more channels: 24 vs. 14 (on the whole, because not all channels are available in all countries).
  • The channels do not overlap: They do in 2.4 with the possibility of transmitting discretely over only 3 channels. Overlapping channels interfere with each other causing interference.
  • Fewer devices use it (till now): Since many devices transmit wirelessly, their signals may interfere with one another. 5 GHz devices are much fewer and so there isn’t much congestion on the frequency.

 

Photo by Liebeskindw:en:Creative Commonsattribution



However, 5 GHz also has a much shorter range and is less able to penetrate obstacles (like floors and walls, which is probably why 2.4 GHz is so popular and used by many devices in the first place). The theoretical maximum speed on the 2.4 GHz band is either 450 or 600 Mbps, while the 5 GHz band speeds may reach up to 1300 Mbps. This is all theoretical though, actual speeds are usually less.


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Not all routers are created equal

In addition to all of the above, there are also different wireless standards that govern how routers transmit and receive signals. These standards were developed by the IEEE and the main two currently used in wireless routers are the older 802.11n (2009) and the newer 802.11ac (2013). Routers that utilize 802.11n are called N-routers, while those using 802.11ac are called AC-routers. N-routers can merge channels to achieve widths of 40 GHz and employ a technology called Multi Input Multi Output (MIMO, also called Single User MIMO or SU-MIMO), which allows the router to transmit and receive from several antennae at the same time allowing a better signal and faster speeds. They can also transmit up to 4 simultaneous data streams.

Photo by Benjamin Baumgärtner - Benbaum Public Domain
 

 

Photo by Sinchen.Lin©



AC-routers can use channels of up to 80 GHz and employ SU-MIMO and an even newer technology called Multi User MIMO (MU-MIMO). This allows a single antenna to provide a data stream for multiple devices. The router packs several antennae and the number of data streams is increased to 8.

Is the tri-band router the best?

In general single-band routers are cheaper than dual-band, and tri-band are more expensive than both. So the price is a major point to consider. Newer dual-band wireless routers come in two flavors: AC-1750 and AC-1900. Remember that AC represents the wireless standard used (802.11ac). The numbers represent the theoretical maximum speeds on all bands combined: 1750 provides 450 on the 2.4 GHz band and 1300 on the 5 GHz band, whereas 1900 provides 600 on the 2.4. Tri-band routers sport the designation AC-3200, which means 600 on the 2.4, and 1300 on either of the two 5 GHz bands. These speeds represent the aggregate bandwidth, though. No one device will be able to utilize all of that; each device will only use one band. Also bear in mind that all these are theoretical maximum speeds. What you actually get will be limited, first and foremost, by the speed provided by your Internet Service Provider (ISP). Other factors include radio frequency interference from other devices in your house or even your neighbors, obstacles, and multiple devices running at once, competing for bandwidth. The devices that use the wireless network (laptops, smartphones, etc.) may likewise be a limitation. Not all devices are running on the 802.11ac standard. The routers are backwards compatible (will accommodate older standards) but the devices won’t be able to make use of the faster throughput.


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The Verdict

A tri-band router may seem like the Hercules of routers, but you may not be getting much value out of it given the state of your home network and devices, and considering the equally Herculean prices, a dual-band running 802.11ac may be a good bet. If you do have internet speeds greater than 600 Mbps and have many devices using Wi-Fi and many other wireless devices, then the tri-band might amp up your speeds significantly. If your ISP only gives you throttled speeds of 15 or 20 Mbps, or you’re on a bit of a budget, and you don’t have that many devices, a single-band N-router would suffice and not break the bank.





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