Improve performance on Digicel’s 4G wireless modem [Part 1]

Late last year, I moved into a new students’ residence on my university’s campus. The residence is set up like an apartment complex with rooms on 6 levels. However, because the place was still new, it was not wired for easy internet access. The closest wireless access points that my laptop could detect proved to be unreliable so I decided to purchase a Digicel 4G wireless modem (Green Packet DX250). I paid for a month’s service and was successful at setting up the device. However, after about the first week, I noticed that the performance started to dwindle. Here is what I did to improve the wireless performance on this device.

First of all, the following recommendations will in no way require opening the device or void any agreement with Digicel. I do not promise that any of these recommendations will unlock speeds that you have never experienced with the device, but they should make the experience more bearable. Secondly, executing these changes is best done if your computer is directly connected via ethernet to the modem (it’s that white cable that came with the unit). You can disconnect it at the end. So let’s get started!

1. Change your modem’s web login password
This might seem pretty obvious, but you should change your modem’s web login password to something stronger so that others do not gain easy access and lock you out of your own connection. Go to your modem’s web address in your browser and click on the ‘Personalization’ page. Enter the old password and the new one, then apply. A strong password is more than 8 characters long and includes numbers, letters and symbols.

2. Choose a wireless mode
Again, log into your modem’s web interface and click on ‘Networking’. Under ‘Wireless mode’, choose something that is most compatible with all wireless devices connecting through your modem. If you only have a laptop that supports 802.11n, select ‘N only’ to take advantage of this wireless technology. However, as many might also want to use non-802.11n smartphones with their modem (especially pre-BB10 Blackberries which cannot see this signal), ‘G/N mixed’ is alright as well. Apply and wait for the unit to restart.

3. Choose a wireless channel
On the same page as before (‘Networking’), you will see that you have the ability to change the wireless channel of the device. Now, explaining this can get technical, so I will explain as best as possible. The wireless channel is the frequency at which your wireless modem will communicate with your wireless devices. Digicel’s modem only allows you to select from channels 1-6 on the 2.4GHz band even though the operable frequency spectrum of other devices can go much further. The important part, though, is to either a.) choose a channel that others are not using, b.) choose a channel that is at least 5 channels away from the busy one, or c.) if the spectrum is congested, choose the channel with the weakest signal. If you utilize a channel that others are also utilizing then your connection will slow down due to interference. Yes, at some times the connection might be fast, but as soon as they start using their wireless, both of your connections will slow down.

Metageek’s InSSIDer (free) for both Windows and Mac will guide you as to which channel to choose. Install it and launch the program. It will scan for wireless signals and show which channels are being used for wireless broadcasts in your neighbourhood. After sorting by RSSI (descending) your wireless modem should be listed at the top as the strongest. Stronger signals are closer to 0dBm. Look at the graphical spectrum display to determine which channels are not as busy or have a weak RSSI. Go back to your modem’s web interface and select this channel. You can exit inSSIDer for now.

4. Adjust the transmission (Tx) power
You would think that leaving the ‘Tx power’ at 100% is always recommended, but that can cause problems as well. Think about it: if you are only broadcasting your wireless signal to cover your small apartment where many other wireless signals from neighbours exist, why crank the power all the way up? If 75% power does not result in a significant drop in performance, use this instead. How is this beneficial? Since you are only covering your usage area, there is less chance of channel overlap and interference from neighbouring networks. Go back to the ‘Networking’ tab and change the ‘Tx power’ to 75% to start. You can dial down to lower power levels, but do not go too low as this might reduce your connection speed.

5. Adjust security settings
Under the ‘Networking’ tab, you will notice that there is a ‘Next’ link at the bottom of the page. Click it to be taken to some more advanced settings. First of all, change the ‘Use Default’ setting to ‘User defined’. Change your ‘Security Mode’ to ‘WPA2-PSK’ and ‘Encryp Type’ to ‘AES’. Enter a random alphanumeric key into the field below and make sure you remember it because this will be “password” required to access your network. Why are you doing this? First of all, WPA2 is the best security mode to use by consumer devices to date because it is more difficult to crack than the others listed. You can use WPA if your connecting devices do not support WPA2, but stay away from WEP as it is very weak. Additionally, I have found that AES encryption is not as bandwidth-hungry as TKIP. ‘Apply’ and allow the modem to reboot if necessary.

6. Adjust your modem’s position
Do not place your wireless modem next to microwaves or other electronics that can interfere with your wireless signal. Because the modem has to connect to the 4G network try to place it next to a window with as little obstruction as possible. Additionally, since it must also broadcast a wireless signal for your devices to connect through, it should be placed in a central area for best coverage. Avoid placing next to thick concrete walls if possible as nothing is gained in that area. To get a more objective measure of the best position for your modem, log in to the web interface and on the first ‘Status’ page, pay attention to 3 things: the signal strength bar, the RSSI (received signal strength indicator) and the CINR (carrier-to-interference noise ratio). Obviously, a better signal is graphically displayed on the signal strength bar as green, but you can rotate and reposition your modem until the RSSI and CINR are within certain ranges. Acceptable values for RSSI are -50dBm to -85dBm. Those for CINR are 10dB to 30dB. If you can get your device to show values within these ranges, you are doing well.

7. Measure your connection bandwidth
Only proceed to this step once you have completed the previous ones. It is also a good way of monitoring changes in bandwidth speed. Let’s see how your hard work has payed off for now! Head over to SpeedTest.net and run a bandwidth speed test through Digicel. If your results show a low ping (<100ms), a download speed of around 5Mbps and an upload speed of under 1Mbps, you're doing pretty good!

Conclusion
Unfortunately, your modem’s performance can change from day to day depending on other factors, e.g. the number of other people accessing the 4G network in your area, their modem’s settings, etc. [This might be the perfect opportunity to educate your neighbours on how they can optimize their networks so that there can be as little interference as possible for everyone.] Sometimes rebooting your router (from within the web interface) can temporarily fix connection issues or simply powering it down for about 20 minutes and powering up again. At other times, you might need to adjust the physical position of the modem using the status indicators in step 6 to guide you.

I hope you found this walk-through helpful. Feel free to post any comments you might have especially if you have any tips for improvement. Good luck!