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I asked this question on StackOverflow and was directed over here, so I'd appreciate any advice.

I'm deploying a smartphone application as part of a live music performance that depends on receiving UDP broadcast packets from a wireless access point. I'm guessing that between 20 and 50 clients will be connected at any one time. I'm aware that a maximum of 20 clients per access point is advised, but as the UDP broadcast packets are ground through the LAN, how would I be able to link multiple APs together?

I'm looking for recommendations on a suitable AP for this. The actual data transmission rates are very low - only a few kB/s - as I'm just sending small messages to the smartphone apps, and there will be no WAN internet connection. I tried it with a few connected peers on an adhoc wireless connection without any problems, but ran into dropped packet issues on an old WRT54G running ddwrt, though it's in pretty rough shape.

What's the best way to do this? I suppose I could limit concurrent wireless connections to 20 clients... but more would be nice.

EDIT: I should also say that it's purely one-way communication; the smartphone application is only receiving broadcast packets, not sending anything.

distorteddisco
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  • Simply connect your APs to a switch. That will take care of sending data between the APs. – Brad Aug 10 '12 at 15:22
  • @Brad Okay, that makes sense. Haven't hit the networking class in uni yet. Should the APs have the same SSID? How would the number of clients be balanced between APs? – distorteddisco Aug 10 '12 at 15:33
  • Yes, give your APs the same SSID, and separate their channels. If you have 3 APs, use 1, 6, and 11. The clients will *roughly* balance themselves out. – Brad Aug 10 '12 at 15:45
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    @Brad The use of channels 1, 6 & 11 are primarily in use for the USA. You may have a different set of channels to work with depending on where you live. You also may want to choose a different channel depending on other APs in the area. – Brent Pabst Aug 10 '12 at 16:24
  • @BrentPabst, Agreed. – Brad Aug 10 '12 at 16:33
  • @Brad You should probably type up your answer and post it before I do :) – Brent Pabst Aug 10 '12 at 16:42
  • @BrentPabst, Go ahead. I haven't bought APs in a few years, and cannot provide a recommendation for hardware. – Brad Aug 10 '12 at 16:44

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Like Brad mentions you can easily connect most Access Points and even consumer Routers to switches and get them to act as simple Access Points. In many cases buying a consumer router and even flashing it with DD-WRT will be much cheaper than buying a specific "Access Point" device and offers much more power and functionality.

So to scale your solution like you asked you simply need to figure out how many clients you can run over a single access point's hardware and software. For the consumer style devices with the standard firmware I wouldn't try to run more than 20. With an alternate firmware like DD-WRT you might be able to pull off 30 max. Your other option is to investigate buying advanced/industrial access points like what are used in large office buildings and schools. These devices can easily support many users, up to thousands of users at once, but they aren't cheap.

Any of the current Linksys or Netgear routers are fairly decent and can provide the connectivity you need. Access points too. I recently purchased two Linksys Wireless-N routers and flashed them with DD-WRT, they support about 40 users total across a single floor of a building and the range is great, especially with DD-WRT sending more power to the antennas.

Typically you just connect a standard ethernet cord from your switch to a switch port on the router or access point and thats all there is to it. Just make sure you observe the proper channel seperation for your locale and for the physical location you are using. Just obtain a free wireless network monitor tool to view the current networks around you and place your devices channels where there isn't much activity.

Brent Pabst
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  • Interesting, thanks for the information. I actually have a Linksys WRT54GL running DD-WRT [micro] and I'm testing my application with it. Interestingly, the UDP broadcast packets arrive in time with no issues when I'm doing a direct ad-hoc wireless network from my computer to my devices (with 5 phones connected), but when I try to run my application with my WRT54GL the packets get super delayed and dropped everywhere, even after prioritizing the UDP traffic with QoS. Would this just be a bad router, or should I try something else? – distorteddisco Aug 12 '12 at 16:30
  • Well that certainly isn't the intended behavior. They should be delivered with little to no delay, especially with no traffic. I wonder if any of the IPS or Firewall functions are hindering things. – Brent Pabst Aug 13 '12 at 01:15
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Look at http://ubnt.com for Unifi APs. Cheap and will do what you need just fine, without getting you too deep into all kinds of networking you don't have experience with (although you're able to do that, too - these just abstract it nicely). I use them regularly and would recommend them to anyone.

I would not touch something that mattered to me with WRT. While some like it, I see it as those who see harleys see their motorcycles; keeping them from falling apart/catching fire/melting is 80% of the fun.

tsz
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