Wireless technology - which is better: more single radio APs or less dual radio APs?

Solution 1:

The Right Answer^(tm) is that It Depends^(tm).

Generally, dual radio APs have higher client capacities than single radio APs, but roughly the same coverage area. Conversely, however, single radio APs can be distributed in a wider area, allowing each AP to use a lower transmit power and spread the client load across multiple APs. It's a tradeoff. More clients in a tigher space generally means that you need more radios.

If you're going to have areas of high client concentration you will typically need fewer dual-radio APs in those areas than you'd need single-radio APs.

Whether your clients are 802.11b/g/a/n makes a different, too, because a network with predominantly 5.4Ghz clients will be able to pack more densely with fewer APs simply because there are more non-overlapping channels and the APs don't have to function as "spotlights".

Solution 2:

Disclaimer: I have a significant amount of experience with Cisco 802.11 APs and WLC 5508s and no Aruba experience except for sales demos.

If both solutions meet your needs regarding coverage and client associations, then "performance" isn't really an issue as it relates to throughput. Personally, I'd go with the dual-radio APs for the obvious advantage of increased performance for newer clients.

I'm not sure what "connection" performance Aruba is referring to, but I'll assume they're talking about total aggregate throughput. When you're talking 69 vs 96 APs in a dense environment, you're probably talking a couple of hundred active users at a time, minimum. Just for round numbers, let's assume you average 1,000 wireless users (or roughly 15 people per AP). Each of these APs are 1GbE back to the controller, but your connection out to the internet will probably be much less than that.

If your connection to the Internet is 500Mbps and you have 1000 concurrent wifi users, their average available bandwidth is about .5Mbps.

The point is that unless you have an extraordinarily fast pipe to the Internet, "performance" doesn't matter as much as coverage and the ability to dynamically adapt to interference and if this is a dense deployment, I'd want both dual-band and Cisco Clean Air.