Hi all,
I am new in openwrt I just planning to yprocure a mini PC and install openwrt as my home wireless router, I just wonder if I need to procure an extra AP for this purpose, or can I setup SSID on the built-in wifi of the mini PC? I walk through the forum and don't see similar discussion. What currently I have in my home network is a NAS device, IP CAM etc
While there are some high quality wifi hardware options avaiable for PCs, they are the exception not the rule. And they may not be well suited for mini-PC form factors due to thermal considerations and the physical arrangement of the antennas relative to the case.
A mini PC can be an excellent wired router, but in almost all cases, you will be better served by a proper external access point device. Even older APs tend to outperform the wifi that is built-in to most comptuers when it come to AP mode operation. (and that's not even getting into the topic of drivers and such which can further complicate the options on OpenWrt).
So, bottom line: I would recommend a purpose built AP for your wifi needs, not a mini-PC with wifi.
Thanks Psherman. So correct me if I am wrong. This is configurable and we don't do this just because of performance/thermal issues, am I right? If this is the case, just want to try first, and buy a new AP when needed
To be honest, I use an old laptop as a Wi-Fi router, VPN gateway, NAS, etc. in a small apartment, and it is not even a bottleneck in my case, so it won't hurt to try if you have a device with compatible specs, as to whether it suits you or not depends on personal needs.
Well, yes and no.
Regarding configuration... this all depends on the wifi specific chipset available in (or for) your MiniPC (either a bundled option, or what will fit into your setup based on the interface type and physical form factor requirements). You want a chipset that is supported by OpenWrt and that has AP mode operation that is reasonably well established (some chipsets do not support, or don't have drivers for AP operation, they work in STA/client mode only, and some wifi hardware isn't supported by OpenWrt at all).
Thermal envelopes will depend on the power dissipation of your wifi chipset/card, and the thermal design of your mini PC (fanless vs active cooling, size/position/CFM rating of the fan(s), plastic enclosure vs metal with large cooling fins, etc.)
Performance, as @vgaetera pointed out, is going to be a personal definition. But, when talking about performance, you have to consider the antenna design, quantity, and position. For high performance wifi APs, the antennas tend to be specifically arranged and then factory calibrated to enable proper multi-stream/multi-user capabilities. Because the positions of the antennas are critical to the wifi performance, this is something that is very carefully designed and controlled by most AP manufacturers, and isn't really possible to achieve in most PC/mini-PC form factors.
More generally, wifi performance depends on your physical environment (including radio frequency noise/spectrum crowding, building materials and floor plan, distance requirements, and the like), and the number of wifi client devices, and the bandwidth requirements.
Of course, your expectations for coverage and bandwidth needs (device-to-device and/or device-to-internet) are what will matter most here, once you actually try it.
So, I agree with @vgaetera that there's no harm in trying it. However, also consider the financial aspect if you'll be paying for the wifi hardware in the mini PC as either a model/option upgrade or an additional purchase... if you're not happy with the internal wifi, you'll likely want to buy an AP.
Thank you all for useful information
What they all said. And, if the mini-PC has a wifi card, sure you can try that. But I'd underline the other points...
A stand alone wifi router (as an AP) would very likely be a better radio and antenna implementation. (and that is an important part)
A separate AP can be placed in better places, for better coverage, than you likely could/would put your router box. That flexibility is nice. You also can have more than one in more than one place!
Less known is (if you run OpenWrt on your AP's) with some chipsets (ath9k/ath10k, MT stuff, others?) there's some cutting edge development of wifi level queuing and fairness stuff that could improve your wifi quality of life, that you usually don't get elsewhere...
Split to two sides - one to have wired router plus switch, two to hang some ceiling ap or something. Make some vlans if You need. Spparate ap is excellent choice because IT might be placed where the hell You want to have good signal coverage and You don't need to change all od this stuff, plus parts of network will work if another part have failure or something.
@Andylcm1105
If you are still shopping, you probably do NOT want a PC with an Intel wifi card, or at least expect to replace the wifi card, as I do not believe these will function in AP mode.
You can use the OpenWRT Table of Hardware to help you identify supported vendors, most of which were noted above. There are a few views that are WIFI focused and include the chipsets and drivers. Ignore the actual hardware, but you can use this to help you identify chipsets and then search for Mini-PCI-e adapters. It may not be straight forward, products are not chipsets or drivers, so you may need to do some more digging.
You should also check the PC Vendors forum for possible issues with changing wifi cards. Not so much an issue today, but there was a time when some manufactures tied the wifi card to the BIOS.
Generally speaking, mini-PCs usually come with Intel Wi-Fi cards, which cannot work in a router because they do not support the access point mode.
Why not get an actual router instead? Go on eBay and search for "Sophos (85, 86, 105, 106, 115)" or "Barracuda F12".
Come to think of it, I still haven't sold my XG 85w 
:
Disregarding wifi related issues and purely from a cpu standpoint, on paper, the Intel N100 CPU based Mini-PCs should be pretty good when looking at power consumption. They are marketed with 6 Watt TDP.