The 802.11ad wireless standard makes wireless networks faster than Gigabit LAN cables and fibreglass. We tried out the high-speed technology
The importance of WiFi speeds has never been more important than it is now. With the emergence of 4K videos, the quantities of data that we need to transfer between devices or download via high-speed fibre internet are on the rise. Furthermore, there are more and more tablets, smartphones and compact laptops with fast – but small – SSD storage. The real-time streaming that becomes necessary overwhelms the current ‘n’ and ‘ac’ WLAN (wireless LAN) standards, which are already struggling to output the required bandwidth using the available 2.4 GHz and 5 GHz frequency bands. Compatible routers can only attain peak values of up to ‘5300 Mb/s’ under theoretical conditions, which only happens if you could simultaneously use multiple WLANs on a router.
You would only be able to send a higher number of Gb/s to a client with the help of the 60 GHz band, which is what the 802.11ad WLAN standard uses. This standard offers a much higher speed, but only over short distances. When we tried out the first AD router, we encountered a promising amount of speed, but also experienced some issues.
This Is What Makes Wireless Ad So Fast
In simple terms, the large amount of available bandwidth in the 60 GHz band is what gives ad WLAN its high speed. A wireless AC (5 GHz) channel has a width of 80 to 160 MHz, while wireless AD can go up to 2.16 GHz and is a system that has much more sub-channels that transport data. Furthermore, on account of the high frequency, it becomes possible to transport a higher number of data packets per second. Theoretically, we’re looking at top speeds of around seven Gb/s. To add on to that, there’s a reduction in the data transmission delay (latency), which makes the technology ideally-suited for transferring high-resolution interactive screen data. It could, for example, be used to wirelessly stream games and movies to high-end displays or virtual reality goggles.
No previous radio technology has ever used the 60 GHz band, because the oxygen in the air severely muffles signals of this wavelength. This limits the range of wireless AD to up to ten metres (within visual range), but it also eliminates the possibility of overlapping channels from other rooms/homes. 802.11ad is supposed to complement the previous wireless standards, so it should work seamlessly on compatible routers. In practice, it should be able to switch over to the 5 GHz or 2.4 GHz band if the ad-connection breaks down. This means that instead of getting disconnected completely, the connection would just become slower as the distance increases. Finally, the short wavelength also results in very small antennas. It would even be possible to accommodate many of these in compact devices. The higher number of antennas leads to better beam-forming and the fact that the signal is aligned towards the remote station in a targeted manner improves the signal quality and efficiency.
‘WiGig’, the predecessor of the 802.11ad standard, was specified at the end of 2009. However, apart from isolated laptop models with wireless docking stations, this technology was not used on a large scale. The first wireless AD router was made available quite recently, but there are as yet no end devices for it.
It is claimed that the speed of this first wireless AD is 4600 Mb/s. At the same time, it is also supposed to attain a rate of 1733 Mb/s in a 5 GHz wireless AC, as well as a rate of 800 Mb/s in a 2.4 GHz wireless N. In total, this adds up to the marketed overall speed of 7200 Mb/s. This new wireless AD router has also been shown to feature eight external antennas, which does give it a rather bombastic look. All in all, the device contains a total of 32 aerials for the 60 GHz band. A multi-user MIMO is supposed to ensure that multiple wireless clients can be fed in an optimal manner. As is usually the case with high-end routers, this model is expected to use a 1.4 GHz dual-core CPU, which will speed up the web interface and data transfers. We used a wireless bridge between two of the new routers to find out just how fast the technique really is.
Layout Of The Ad Test Track
The high-frequency wireless AD was new territory for us as well and proved difficult for us during the setup for the connection between the two routers. Of the two test routers, only the router with the old firmware version 1.0.0 could be connected as a client to the 60 GHz WLAN of the other router, which was acting as the host. The other router had to be used as the host, because its newer version 1.0.10 (neither one of the two routers offered any updates) made it unable to connect to the previous router in the same fashion. In addition, the host router’s 60 GHz WLAN must be active, plus its SSID (name of wireless connection) and MAC address must be known for it to work. This information is all displayed under “Advanced | Status | Wireless | 60 GHz”.
When it came to the client router that had the old firmware (1.0.0), we selected “Dynamic IP” as the internet access option in the initial installation wizard. For our tests, we set a different IP address (192.168.0.2) within the same sub-network as the host (192.168.0.1), under “Advanced | Network | LAN”.
The actual option for installing the 60 GHz WLAN bridge for the access point is wellhidden. To find it, you have to go to “Advanced | System Tools | System Parameters | 60 GHz WDS | Enable WDS Bridging”, which is a lot of layers to find an option. We also had to manually enter the SSID, MAC and WPA key, because the “Survey” function for scanning available 60 GHz networks wasn’t working. After that, we had to deactivate the DHCP server under “Advanced | Network | DHCP Server”.
The end result was that we had two computers that were connected to the client router, with the IP address given by the host router and data traffic travelling between the routers through the 60 GHz WLAN. We took our measurements using a PC that was connected to the host router, as well as a laptop that was connected to the client router.
Cable Puts The Brakes On The WLAN
The test arrangement turned the connection between the computers and the routers into a brake, because the routers ‘only’ support the well-established Gigabit LAN (which was always fast enough in the past). When it comes to cables, since both routers can transport a maximum of one Gb/s, this essentially caps all wireless measurements. In this regard, the measurements consistently indicate that wireless AD is faster than LAN cables. Additionally, when the routers are right next to each other, the measured values are at the level of the Gigabit threshold, which doesn’t change for distances of up to several metres. The speed only takes a hit if the arrangement involves larger distances or if there are obstacles. However, when it comes to the daily routine, this shouldn’t really be a problem for future ad-compatible end devices. After all, PCs and NAS servers that are designed to be used at home have Gigabit LAN connections. Furthermore, even the fastest fibre internet connections can ‘only’ attain speeds of up to 1000 Mb/s. At the very least, 802.11ad ensures that the WLAN doesn’t slow things down.
Infrastructure For Wireless AD
If you want to make the most of the speed available to wireless AD, you would have to completely replace existing network hardware. The AD system will only be able to run freely without any brakes if every single component clearly exceeds the Gigabit LAN limit. This can be achieved using two technical approaches. Firstly, the use of an SFP+-type port. With this installed, a wireless AD router can transport up to 10Gb/s to other SFP+-capable devices, such as professional NAS storage devices, or a PC with an SFP+ network card. The second approach is to use a ‘link aggregation’ feature to form a two Gigabit line by interconnecting two regular Gigabit LAN ports, which can help to quickly link multiple NAS models or PCs with two LAN ports. This linking process must be set up on both the router and the end device for it to work. Now, the jump in speed isn’t as large as it would have been in case of SFP+ (two instead of 10Gb/s), but there is a larger amount of compatible hardware. Furthermore, normal LAN cables can be used instead of the expensive SFP+ cables.
Surprising Test Results
We selected three measurement methods in order to obtain theoretical and practical test results for 802.11ad. The first one involved the iPerf synthetic benchmark, which measures the network bandwidth in Mb/s. Furthermore, we also used the FTP to transfer six files with a total size of 7.7 GB in three simultaneous transfers. For the sake of the conversion process, we specified the FTP speed in MB/s. Finally, we used an internet speed test to determine the ping time for an internet server in milliseconds. This is, for example, important for online gaming, video chats and voice calls. We ran all the tests in conjunction with three different distances.
Our FTP measurements were initially a lot slower in comparison with the iPerf values, with the whole thing showing at about 60MB/s. The sluggish writing performance of the SSD in one of the test computers slowed down the simultaneous transfers, but we were able to reach the limit of the Gigabit-LAN connection when we started using a faster SSD. Which means that to have the kind of fast network that wireless AD can provide, high performance drives are required to keep up with the data transfer rates.
Performance Remains At A High Level For A Long Time
During the initial set-up of the test arrangement, the two routers were only a few centimetres away from each other. This led to results that hit the Gigabit threshold, but it also led to frequent dips in performance. Based on the two-metre table we placed the routers on, the average drop was about 5% of points in performance score. Increasing the distance between the units actually made the connection more stable.
The fact that the AD routers attained the exact speed of their Gigabit LAN connection when in visual range and a gap of two metres wasn’t all that surprising. However, we didn’t expect the speed and ping time to remain at practically the same level up to a distance of eight metres. Encouraged by this, we then used a location that was within visual range and at a distance of twelve metres. However, the 60 GHz band was completely and totally silent at this location, which proved that it got cut off at some point after eight metres.
A usable connection was established at a distance of ten metres, but its data rates fluctuated drastically. This applied in particular to situations in which there was movement in the room, such as when colleagues passed through the line of sight and between the routers, the speed temporarily and immediately went down to zero. On the other hand, cardboard and paper obstacles had no effect on the system. The specified average values were measured in the absence of such interference.
The iPerf measurements for distances of more than ten metres were just about fifty percent of the 8m results. On the other hand, the FTP transfer procedure – which took almost 23 minutes – suffered a lot more on account of the unsteady 10m connection. To be exact, the results showed that the speed in this case was just five percent of the 8m speed. We believe that the FTP connection collapsed during the transition from eight to ten metres because of a steeply-rising error rate. Consequently, several data packets had to be transferred many times before the whole thing worked properly. We didn’t expect the range limit of 802.11ad (which is caused by the oxygen in the air muffling the signal) to be so selective.
The internet ping times for a distance of up to 8m were no worse than they would have been if a cable connection had been set up with the main router. This strengthens our hope that high-frequency wireless AD would be ideal for online games and interactive network applications.
We then took the same measurements between the routers with a 5 GHz connection (wireless AC). When it came to the iPerf bandwidth measurement, the 5 GHz network attains values that are somewhat lower than those reached by wireless AD, but it can be used without any speed drops up to a distance of 12 metres (it probably would have been functional at greater distances too, but we ran out of room).
When it came to the AC-based FTP process, even though the measurement procedure was the same as that used for wireless AD (three simultaneous file transfers), the speed was a sluggish 32.2MB/s. When we ran a cross-check with just a single active file transfer (all files successively), we realised that the first few hundred megabytes of each file were only being transferred at the rate of approximately 30MB/s, after which the speed climbed up to 90MB/s. Despite this, the 5 GHz bridge only managed an average rate of 34.1MB/s. In comparison with AC, the higher-frequency AD seems to be better at managing parallel file transfers. Furthermore, if the connection is good, the new standard upscales the transfer speed more quickly.
Bringing Wireless Ad Into The Future
Unfortunately, the Gigabit-cable brake prevents the router from taking full advantage of the speed that’s made possible using the 802.11ad standard. Nevertheless, there are scenarios in which the router would be useful. For example, if you want to use a laptop/tablet/2-in-1 device to work on files stored on a Gigabit NAS device, then AD will be able to provide you maximum throughput - at least at short distances. That’s all the more reason to be excited about some of the new routers that would be coming out this year, which will have features that resolves this limitation, or at least offer some workaround for it. Furthermore, the new routers would be great if you plan to build a new high-speed infrastructure. There are PC vendors that already have plans to release products with wireless AD compatibility in 2017, which is for anyone who’s planning to upgrade to look out for.
The killer application of the new wireless standard is already in view. Thanks to high bandwidth and low latency, it will be able to provide data to ergonomic and wireless VR goggles. In addition to this, AD connections may also replace HDMI cables, which in turn would simplify things like office presentations. Until all this happens, 802.11ad will remain just a fascinating technology. But there’s no denying that it’s exciting news to have a wireless standard that manages to be faster than even the long-serving Gigabit LAN.