ASUS RT-AC66U Wireless 802.11ac Wi-Fi Router Review


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Passmark Advanced Network Test Results

The first test was conducted at a distance of 10 feet, which is slightly more than double the minimum recommended distance of 1.5 meters. ASUS suggests reducing the transmitting power of the router and the adapter if they are located any closer than 1.5 meters. The default transmitting power is set at the factory to 80mW. In this test, the router and adapter were located at approximately the same height and there was a clear line-of-sight between the two sets of 3×3 antennas, with no obstructions.
The first thing to note is that these benchmark results show ‘Real-World’ throughput. Nobody using Wi-Fi is actually getting the throughput performance that’s highlighted on the front of the manufacturer’s box. Those are theoretical numbers, and they refer to the raw data bitrate that’s possible with the hardware in question. In this particular test, with the router and adapter in the same room, I did achieve the theoretical maximum data rate of 1300 Mbps, as indicated by the monitoring software that was included with the wireless adapter. But, between the data encryption that I was running and the error handling overhead of the various communication protocols, the effective data rate is always going to be much lower.
ASUS RT-AC66U 802.11ac Wireless Router LOS Passmark Results
TCP results for the three routers under test were strong in the line-of-sight test, with the two 802.11n routers pulling in throughputs in the mid 70 Mbps range. The ASUS RT-AC66U easily bested that with 802.11ac performance in the mid 90 Mbps range. UDP performance was another story altogether. The TRENDnet and Linksys routers both threw away more than 80% of the bits transmitted with this protocol. The RT-AC66U had a very low rate of bit loss at this short distance, and there were some trials where there were zero bits lost. That’s extremely rare for a UDP data stream. The effect of all that is clearly shown in the results, where the ASUS had an average transmission rate of 369 Mbps and the closest performance with an 802.11n router was 63 Mbps.
ASUS RT-AC66U 802.11ac Wireless Router 20 Feet  Passmark Benchmark
Moving the PC and Wi-Fi adapter into an adjacent room, with double the distance and multiple obstructions between the antenna arrays reduced the effective transmission rate slightly. The ASUS RT-AC66U went from an average throughput of 95 Mbps to 87 Mbps. That’s an 8 percent reduction, but in real life, you probably wouldn’t notice it. The Linksys actually gained two megabits per second in this test, and had an average rate of 75 Mbps. The TRENDnet lost about a third of its throughput, and ended up with a 50 Mbps rate in this test. The UDP benchmarks followed a similar trend, with the ASUS still maintaining a throughput well over 300Mbps. The Linksys stayed about the same, and the TRENDnet lost about 30% of its throughput at the longer distance, with obstructions. None of these performance losses would translate to a noticeable difference for web surfing, but file transfers, data backups, or HD video streaming might be affected.
ASUS RT-AC66U 802.11ac Wireless Router Downstairs  Passmark Benchmark
Using your Wi-Fi device one room removed from the router is hardly the most challenging test, so in order to up the ante I dragged the test PC downstairs to the room that’s furthest away from the router location. That room happens to be the pantry, that’s right next to the kitchen. Both rooms have a high packing density, with lots of wood and metal items to block and deflect radio waves. The only thing more challenging would be to go over to my neighbor’s house. The higher performance of the 802.11ac standard is really evident here, where the ASUS RT-AC66U held on to most of its line-of-sight performance levels. The TCP throughput was back up to 96 Mbps for the ASUS, while the other two routers dropped back to 66 and 51 Mbps. In UDP, the ASUS stayed above the 300 Mbps rate, and the closest the 802.11n routers came was 43 Mbps.
ASUS RT-AC66U 802.11ac Wireless Router Beam Forming
I want to show one chart that demonstrates the beam forming capability of the new 802.11ac routers. After about 90 seconds, the Broadcom BCM4360 radio chip inside the ASUS RT-AC66U has completed an analysis of the three separate RF signals going back and forth between the two 3×3 antenna arrays, and has adjusted the phase of each of them to generate a coherent wave front. This has the same effect as making the signal stronger, which then increases data throughput, as you can clearly see. There is an increase in real-world throughput of approximately 20% with this technology, if implemented correctly, as ASUS has done here. This technique is old hat in the RF world – it was invented in 1905 and actually implemented by both sides during WWII. If you ever noticed the four short antennas arranged in a 12″ x 12″ square on the trunk of a police cruiser, then you’ve seen a multiple-input multiple-output (MIMO) antenna system in action. Beam forming was actually introduced in the 802.11n Wi-Fi standard, but hasn’t really been successfully implemented until now, with the new batch of 802.11ac routers coming into the market. There’s been a lot of conjecture about how well it was going to work, and now we have the answer.

Clearly, none of these results are anywhere near the typical wired data rates of 1 Gbps. The UDP rates aren’t bad, consistently above 300 Mbps with compatible hardware, but the TCP throughput carries a mighty high burden of communication overhead. Two other things stand out to me, as I review these benchmarks. One, the new 802.11ac standard is worth it, in terms of enhanced coverage and increased throughput. Two, there is a very real and measurable difference between the best wireless routers and the rest. I can’t say that the ASUS RT-AC66U is THE best, because I haven’t tested them all. I can say that its performance was always a step or two above the other units in this test. It’s also the most expensive, but the extra features and capabilities you get are worth the investment, IMHO.


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