By Joseph Moran

August 26, 2011

Dual-band routers can be a boon to your wireless network, as long as you prepare and know what to expect.

If you’ve been shopping for a new 802.11n Wi-Fi router recently, you’ve probably noticed that many models boast dual-band support — that is, the capability to operate not only on the 2.4 GHz frequency typical of most routers, but on 5 GHz as well.  

Routers that support  802.11n at both 2.4 and 5 GHz, like the Linksys E3000, tend to be somewhat pricier than standard models, but they also offer real benefits to your Wi-Fi network. Before shelling out extra for one, however, you’ll want to be aware of the pros and cons of 5 GHz technology, and ensure you’re properly equipped to take advantage of what it offers.  

Here are the five pros and cons you need to know about 5 GHz Wi-Fi to determine whether a dual-band router might make sense for you.

1. PRO: No interference from other devices

The biggest advantage of 5 GHz 802.11n over 2.4 GHz is that the former’s not susceptible to interference from the myriad wireless devices you might encounter in a typical home or office. Cordless phones (older ones rather than today’s 1.9 GHz DECT-based models), Bluetooth devices, microwave ovens , baby monitors, alarm systems, wireless speakers, or any other device that emits RF signals at 2.4 GHz can wreak havoc with a Wi-Fi network running on the that frequency.

By contrast, a network operating at 5 GHz sits peacefully above the fray where interference from other wireless devices is virtually non-existent.

2. PRO: Less crowding from other networks

As it turns out, one of the most common sources of interference for Wi-Fi networks is other Wi-Fi networks, which gives 5 GHz another leg up on 2.4 GHz.

While 2.4 GHz Wi-Fi routers can be set to run on one of 11 wireless channels, the signal spreads out through several channels on either side of the one you select. This means there are only three channels — 1, 6, and 11 — that can be used simultaneously without any overlap (and use of 802.11n’s optional higher-performance double-wide channel mode effectively reduces the number of non-overlapping channels to just 1.)

The upshot is that there’s little to no room in 2.4 GHz band for multiple wireless networks to peacefully coexist in close proximity.

A 5 GHz network (which actually uses a wide frequency range between approximately 5.1 and 5.8 GHz) avoids this overcrowding problem by offering anywhere from eight to 23 non-overlapping channels (depending on implementation and whether or not double-wide channels are being used). This lets many more nearby networks live together without stepping on each other.

3. CON: Limited range

Generally, the lower the frequency the farther a wireless signal can travel. Therefore, devices on a 5 GHz network will tend to have a shorter range than those using 2.4 GHz. This can be mitigated somewhat with sophisticated antenna technology, but if a given device is relatively far from the wireless access point, you may have better luck connecting via 2.4 GHz.

4. CON: Limited support by devices; higher cost

In an ideal world, every 802.11n device would give you the choice to connect to either a 2.4 or a 5 GHz network. But in the real world, it’s not quite that simple because 5 GHz support is far from universal — sometimes it’s an extra cost option, and often it’s not available at all (at least not built-in).

For example, if you’re buying a build-to-order notebook from a company like HP or Dell, you can probably upgrade to dual-band wireless for a relatively modest charge. On the other hand, if you’re buying a fixed configuration notebook you’ll likely find its Wi-Fi adapter only does 2.4 GHz, so to make such a notebook 5 GHz-capable will require the extra expense and bulk of a USB adapter like the Netgear N600.  (Though teensy-weensy Wi-Fi USB adapters are commonplace, we haven’t yet found one that does 5 GHz.)  

 And 5 GHz support can be similarly hit or miss when it comes to wireless consumer electronics devices. For example while the iPad 2 supports 5 GHz, the iPod touch and iPhone only do 2.4 GHz. Some of Roku’s previous generation streaming media players included 5 GHz support, but it’s not available in any version of the new Roku 2. Moreover, neither the Xbox 360 nor Playstation 3 do 5 GHz (actually the latter doesn’t even support 802.11n yet).

To get fixed-location devices like set-top boxes and game consoles on to a 5 GHz network regardless of whether or not they support 5 GHz natively, use a 5 GHz Ethernet bridge like D-Link’s DAP-1522.    

5. PRO: Two networks are always better than one

Due to the aforementioned limitations, rarely will you be able to kick 2.4 GHz to the curb and run a pure 5 GHz network. But even if it’s only feasible to get a handful of devices onto 5 GHz, it’s often worth the effort and expense. Since Wi-Fi networks are a shared medium, the more devices that are connected to a given network, the less bandwidth is available to each device. Therefore, moving even a few devices into the 5 GHz realm will leave more bandwidth available for the devices on 2.4 GHz to share. 

One last thing — if you decide to take the plunge on a dual-band router, be sure the one you choose supports both 2.4 GHz and 5 GHz 802.11n simultaneously. Some models can only do one at a time, which means that if you turn on 5 GHz, your 2.4 GHz network will be limited to 802.11g.