Which Wifi Router I should buy ?

This is a very hard question to answer as everyone's needs are different. And there are so many types of consumer products available in market from  prices starting Rs. 800/- to Rs. 30,000/- while enterprise ones go from $500-$1300 USD. Besides their is a huge gap between the promised theoretical speed labels on the packing box and what is practically achievable when deployed.

Here are some grades of Routers/APs based on application domain:

(1) Consumer Grade  - Belkin, Tp_link, Dlink, Asus, Linksys, tenda etc (FROM $20-$400)
(2) SOHO/SMB Grade - Ubiquiti (Typically $100- $200) - The best option for advanced users
(3) Enterprise Grade - Cisco/Meraki, HP/Aruba ($500-$1000) - Only for offices and workplaces with high density of WiFi Users
(4) Carrier Grade - Ruckus Wireless ($1000+). Suitable for WiFi Hotspots deployed by fixed line carriers

(3) and (4)  offer enterprise features which most users do not need, are hard to configure and therefore these routers are an overkill for the home environment besides being ridiculously expensive. Even though some of the radio performance and technology in them is extremely suitable to high density scene like apartment.  Therefore home users must straddle the lines in (1) and (2) based on what their needs are.

 Let see some evaluation criteria and then they to make a decision (sorry I cannot cut a long story short on this one):

Router capability (Speed label and Antennas):

Refer the illustration below:

802.11g (obsolete) used to support 1 antenna and work at a peak theoretical speed of 54 mbps.

802.11n (mature) supports 3 antennas and can work at 450 mbps max (with all 3 antennas)

802.11ac (emerging) supports 8 antennas max. With each antenna it can do upto 450 mbps per antenna (commonly its 3 and 1350 mbps). Or 3 times 802.11n

The above are all theoretical speeds, Real world we can get at max (varies from deployment to deployment greatly based on interference from neighbor) about 30MB/s (or 240 mbps) and 90 MB/s  (or 720 mbps) with a 3 antenna configuration. 

Most important to note is that the above speeds are cumulative for the router not per client. So to really tap  this speed a client must have the max. no of antennas. If their are two clients with max. no of antennas then speed of each is half of above, if 4 then its just one fourth (and if all are operated simultaneously).

Client Capability:

Lets see the client antenna situation on various devices:

• WiFi USB Dongle - Typically 1 or 2 antennas
• Smartphone - Typically 1 antenna to improve battery life and save space.
• Tablet (iPad) - Frequently 2 Antennas
• Laptops - Frequently 2 antennas (3 on desktop replacements)
• PCI card on PC - 1-4 antennas depending on the model you buy

What this means is that if your client has N antennas then it can reach only 54, Nx150, Nx450 mbps speed (with 802.11g, n and ac respectively) theoretically (or 1/3rd of that in real life). 

So if you have a 802.11ac smartphone (likely with one antenna), you will not exceed 30 MB/s transfer rate in real life. With 802.11n this would be capped to 10 MB/s


Additional features:
USB ports (for connecting Hard disk/pendrive, Dual WAN, Media servers, Print serever etc. These are needs of a few power users and for those few these decisions can come after you have settled on an option based on client & router speed

To summarize, do as under:

1. Skip 802.11g altogether. Technology is obsolete. all 802.11n and 802.11ac have backward compatibility with 802.11g, so that  takes care of older devices
2. Based on the type of client support you have and their number go for either 802.11n or 802.11ac (remember that ac routers are expensive while n routers are very cheap). 
3. Their is little using buying 802.11ac router when you have no 802.11ac client. You might consider a replacement when you have those clients and need the faster speed absolutely (not that feature is by default). With time both clients and router prices will drop (every 6 months or so as new models emerge)
4. If you are small family its unlikely you will be having more than 2-3 simultaneous clients downloading data using though many more many connect and therefore you do not need more than 1 or 2 antenna device.
5. Then of-course your need for extra value added features (USB drive, Media server, Printer etc)

For most people the heaviest bandwidth applications is to watch 1080p HD video streams and that requires no more than 10 mbps (little  1.25 MB/s) even with 3D. At max two such streams will be played in home simultaneously and therefore 20 Mbps is the max speed one needs from Wifi (and Broadband connection too ...). Therefore I generally believe a 2-antenna 802.11n router [eg. TP-Link TL-WR841N or TP-Link TL-WR841(N/HP)]  is the best bet for most of the homes. Anything more is luxury or just for bragging rights.

Personally I have a small family of two adults and one kid, with max two devices being used at a time have a Rs. 800 1-antenna 802.11n router and a Rs. 17000/- 3-antenna 802.11ac one,  and I am equally happy with the Rs. 800/- one. That's what made motivated me write this post to prevent others from unnecessarily blowing their wallet in a heavily depreciating asset.

- Suman Kumar Luthra @ APRC-P3 Telecom Sub-Committee