Within most enterprise manufacturers who sell both 2×2:2 and 3×3:3 platforms, the ratio of overall sales is 80-85% 2×2:2 and 15-20% 3×3:3. Given those numbers, someone might ask why do manufacturers bother building 3×3:3 platforms at all. The singular answer is muscle flexing. It’s little more than a marketing strategy in most cases.
Because the whole thing is a marketing ploy, high-end APs must be performance-oriented in every way. They must have high-end enterprise chipsets, the amplifiers and filters must be first-rate, there are more antennas, and the software must be performance-tuned. Many vendors pay for so-called “independent” testing to show end users how great their performance is using these 3×3:3 APs. How many 2×2 tests have you seen?…and yet that’s what sells the most, no?
There’s a bad assumption that happens during this process. Vendors hope that the end user will say to themselves, “If this vendor’s 3×3:3 AP is high performance, then obviously their 2×2:2 AP must be high performance also!” This is a bad assumption because many vendors build several levels of 2×2:2 and 3×3:3 hardware, each with different target performance metrics for throughput and density handling. Additionally, not all APs support all features (whether security or performance related).
Cost of Goods
The cost to build a high-end 3×3:3 AP is far beyond that of high-end 2×2:2 AP, and so the end-user prices must be much higher also. The ratio of COGS-to-LIST is usually between 6:1 and 7:1. This ratio allows vendors to pay for the R&D of working with hardware and software ODMs to develop customized hardware and software and to pay for the sales and support channel. The range you can expect for COGS would be ~$50 at the low end for a 2×2:2 AP and ~$225 at the high end for a 3×3:3 AP. Keep in mind that two specific things that drive an AP’s cost way up are hardware customization and high-quality components. Some of the costs can be offset by buying lots of units (provided that the manufacturer can sell them), and while manufacturers negotiate hard with their ODMs, costs are only modestly negotiable in most cases.
Design, Design, Design
The point of this blog is to talk about the performance differences between 2×2:2 and 3×3:3 systems and whether 3×3:3 units are worth buying at all. I’ll start by saying that it all depends on the network design. In some designs, 3×3:3 is better and can save money overall. In some designs, the end user would get no added value from 3×3:3 APs.
There are far too many scenarios where Wi-Fi is used to go through even a small fraction of them in detail, so I will focus on areas for consideration.
Most Wi-Fi client devices today are 1×1:1, 1×2:1, or 2×2:2 capable. There certainly are 2×3:2 and 3×3:3 capable client devices, but they are the minority and likely will be for a very long time to come.
What do client devices that are not capable of three spatial streams (3SS) get from an AP that is 3×3:3? Two things:
- Slightly better reception at the AP (of signals transmitted by the client) because the 3rd AP receiver adds value to the MRC algorithm. How much better? It completely depends on the physical environment, so it’s impossible to quantify without testing in your specific environment.
- Slightly better signal strength at the client (of signals transmitted by the AP) when the number of spatial streams is less than 3 (as they always would be) and the AP uses STBC, TxBF, or other similar signal-boosting techniques. How much better? It completely depends on the physical environment, so it’s impossible to quantify without testing in your specific environment.
Is it worth the extra cost (price of AP, support cost, etc.)? In a coverage-based design, it can be. Before you say, “whoa there Nelly…we don’t do coverage-based designs anymore!”, consider warehouses, manufacturing plants, and other environments where there are only a very few client devices, and the main goal is solid connectivity with minimal cost. That’s certainly not to say that 3×3:3 APs are required for solid connectivity, as there are many additional ways to achieve that goal, such as use of directional antennas, dynamic antenna systems, and providing more APs such that coverage is more uniform. My point in mentioning this is to say that using 3×3:3 APs is one way to have a more stable signal in a coverage-based design.
What if your network design requirements are based on handling maximum capacity? Should you use 3×3:3 APs then? It depends on your client population. If many/most of your clients are capable of 3SS, then sure, go ahead with 3×3:3 APs. Why? Because a 3SS connection, in a well-designed network, will yield a faster connection, which will then allow for less airtime utilization for most transmissions. If most of your clients are currently 2×2:2 (and won’t become 3×3:3 within the lifetime of the APs you’re buying), then it makes sense to save some money and go with 2×2:2 APs. Design always goes back to considering your client population. If BYOD is part of your environment, then consider that most client devices will not be 3SS capable.
When 3×3:3 is really 2×2:2
Some manufacturers make mid-range 3×3:3 APs (based on CPU, RAM, Flash, throughput capability, feature set, etc.), and sell them at 2×2:2 pricing in the hopes that they will be successful on spec sheet comparisons alone. It’s important to note that when you see 3×3:3 APs priced like 2×2:2 APs, you should consider the hardware quality and software capabilities of the 3×3:3 units. There’s no such thing as a free lunch, and you get what you pay for. All of these vendors compete hard and offer discounted pricing, so if the pricing is a bit confusing at first glance, there’s a reason. Feel free to compare the performance and feature set of such 3×3:3 APs to similarly-priced 2×2:2 APs.
Two Classes of 3×3:3 APs
When 3×3:3 APs were first released, all of the vendors had to flash their biceps by building high-end units first. The very moment their high-end 3×3:3 hit the market, they immediately put all resources into a 2×2:2 AP. Because they were selling 80%+ 2×2:2 units, and they realized that the COGS were way too high on the 3×3:3 units, they began building another 3×3:3 AP that cost less (and therefore had less performance). The added performance capabilities of the high-end 3×3:3 is almost never used by anyone. The next step, ironically, was to differentiate the high-end 3×3:3 from the mid-range 3×3:3, which is important if you want to sell ANY of your high-end 3×3:3 units. Such marketing is usually based on CPU and RAM related capabilities, e.g. Application Visibility & Control (AVC), integrated RADIUS (and other services), etc.
Customers are usually (defined as a ~4:1 ratio) fine with 2×2:2 units, so buying a mid-range 3×3:3 AP at a reasonable cost (e.g. not much more than the same manufacturer’s 2×2:2 AP) is often a pretty simple decision. The high-end 3×3:3 APs are often left for dead as soon as the 2×2:2 and mid-range 3×3:3 APs are on the market. It’s a very silly, out-of-touch process if you ask me. Someone should talk to customers about what they want and need rather than basing product strategy around “keeping up with the Jones.”
Because manufacturers AP sales are usually 80% or more of the 2×2:2 flavor, then they are more apt to give you a deal on them. More sales volume means that they can negotiate with their suppliers for lower COGS, which they do periodically.
In most cases these days, the best value is with either:
- High-end, enterprise-class 2×2:2 APs
- Mid-range, enterprise-class 3×3:3 APs
The premium you pay for high-end 3×3:3 APs is seldom worth the money, and the money you save buying low-end 2×2:2 or 3×3:3 is rarely worth the pain-in-the-neck of short-changing yourself on performance or features.
Hopefully this was helpful information, and I would love to hear your comments. Perhaps you could add additional information that will be helpful to the audience.