I focused on measuring throughput between two ENS200s over varying distances on a clear day. To ensure clear line of sight, I constructed a pair of 8' high free-standing posts and mounted the ENS200s at the top of each post as shown below.
I configured the two ENS200s per EnGenius' recommendations, with one in WDS Access Point mode and the other in WDS Station mode. I gave both devices a static IP address, set the Access Point to 802.11n only and set up WPA2 security with AES encryption.
I used the Site Survey tool to scan for surrounding SSIDs, channels in use and signal level of each detected wireless network in my test area. The ENS200 detected quite a few different networks, but they were far enough away to safely use the 40 MHz channel mode. Further, the detected SSIDs on channel 6 had the weakest signal strength, so I used channel 6 even though it is a commonly-used channel.
Transmit power can also be tweaked in the Wireless Advanced Settings menu shown below. For my outdoor tests, I left it at the default setting of 20 dBm. (The maximum transmit power on the ENS200 is 26 dBm. Each 3 dB increment doubles or halves power.) At the maximum transmit power setting, EnGenius reports that two ENS200s can establish a point-to-point connection up to 1 kilometer apart.
Transmit power setting
To test throughput, I used iperf with default TCP settings and a TCP window size of 8 KB. I ran iperf on two PCs running 64-bit Windows 7 with their software firewall disabled. I repeated each of my tests three times in each direction and averaged the results.
Jperf is Java based software that provides a graphical output of iperf throughput measurements. Below is a jperf display of throughput between ENS200s 50 meters apart. The drop in throughput between 45 and 50 seconds is possibly due to a temporary interference in wireless signal, something hard to avoid in a residential area.
50m test results
Below is a jperf display of throughput between ENS200s 100 meters apart. Notice the consistent throughput at each interval.
100m test results
Below is a jperf display of throughput between ENS200s 150 meters apart, again showing very consistent throughput.
150m test results
Before completing this review, I shared my findings with EnGenius, and they were surprised my readings were not as high as theirs. As summarized in the table below, my measured throughput using iperf was between 11.5 Mbps and 26.9 Mbps, while EnGenius said they measured the ENS200's throughput up to 60 Mbps!
You'll notice in the far right column I also added measurements for file copies that I performed at the 20m and 100m distances. For these measurements, I copied a 783 MB file across the ENS200 wireless network and calculated throughput based on file size and time to complete the copy.
|Distance (m)||Uplink (Mbps)||Downlink (Mbps)||File Copy (Mbps)|
Throughput test summary
There are a few take-aways from these measurements and discrepancies. One, the jperf graphs show pretty stable and consistent throughput at each distance from 50 meters up to 150 meters. Two, my file copy results of 78.3 Mbps and 62.0 Mpbs, and EnGenius' report of 60 Mbps, indicates that iperf likely understates the ENS200’s real-world application throughput. In fact, I was able to copy a file at approximately 62 Mbps over a 100 meter wireless connection. That is impressive real-world wireless performance!
To further quantify how much iperf might be understating the ENS200's actual throughput, I ran another check in my lab. I set the two ENS200's about three feet apart and configured them in WDS Bridge mode with WPA2-AES encryption. I turned the power down to the lowest setting of 11 dBm to avoid receiver overload, set the radio to 802.11n and used a channel mode of 20 MHz, which resulted in a 65 Mbps link rate.
I repeated my jperf tests with its default values that include a TCP window size of 8KB and measured throughput of 14.4 Mbps for both upload and download. I ran a few more tests at different TCP window sizes and maxed my indoor throughput at 30.3 Mbps with a TCP window size of 200KB. So next time, I'll be using the larger iperf TCP window size for testing.
As a last performance note, I also tested the ENS200s at 50 meters apart with a few trees (no leaves, though) between them. Performance was essentially the same as measured in my 50 meter clear line-of-sight tests above.
Current street price for the ENS200 runs $60 - $65. So a pair of these devices for a point-to-point solution will run you $120 - $130.
In my experience with enterprise networks, it typically costs anywhere from $100-$200 per wired Ethernet connection from the data closet to a workspace inside a building. Running cable outside a building is significantly more expensive, since it involves more expensive weather resistant cable, plus labor and equipment to bury or suspend that cable between two endpoints. If the distance exceeds 100 meters, fiber optic cable will usually have to be used, which adds even greater expense.
There is an expense to installing a pair of ENS200's outside, too, since you still have to run a cable from the ENS200 back to the LAN on each end. In many cases, though, installing the ENS200 could be a DIY project or relatively inexpensive task for a cabling contractor. The bottom line is a pair of ENS200s will likely be a significantly less expensive solution to connect two buildings than running cable between them.
EnGenius states the ENS200 is targeted at businesses for the point-to-point application, but I can see residential applications as well. At $120 per point-to-point network, two or more adjacent houses in a neighborhood might connect their networks and share an Internet connection. If two neighbors were to connect their networks with a pair of ENS200s and share a single $50 Internet connection, they could be saving money in less than three months! (Ed. note: They also would likely be violating their ISP's Terms of Service and, if caught, both end up with no service.)
EnGenius' ENS200 provides a simple inexpensive, easy to set up solution to wirelessly and securely connect two points up to 1 kilometer apart or enable long range connections to an 802.11 wireless ISP or hot spot. So after years of indirectly recommending EnGenius wireless bridges, we can finally provide a personally-verified thumbs-up!