How to Measure & Improve Mobile Broadband Reception

Monday 22nd June 2009 by Anthony in How to Guides, Mobile Accessories.

Note: This post is part of a series of posts about improving reception for Mobile Broadband dongles.

You may be interested in the other posts in the series:

The Problem with Mobile Broadband

Mobile Broadband has really taken off in the past 12 months – and USB Mobile Broadband dongles are now aggressively promoted by all UK mobile networks (3, Vodafone, t-mobile, Orange & O2) as a viable alternative to traditional fixed-line broadband.

However, we’ve heard from our customers that some of them are far from happy with the quality, reception and signal strength of their Mobile Broadband dongles. But the mobile networks continue to promote Mobile Broadband as if coverage is not an issue. Last year, the ASA even went as far as reprimanding a mobile network for some misleading advertising claims.

At Mobile Fun, we’re not entirely convinced that the quality issues surrounding mobile broadband have been fully addressed. Okay, so UK mobile networks are investing heavily in network infrastructure, but we don’t believe that customers are getting adequate coverage, signal strength, or reliability with their Mobile Broadband dongles.

About this article

We’ve written this article to help people understand the issues surrounding Mobile Broadband reception – and to show how network reception can be measured to help improve the quality of Mobile Broadband connections.

In our testing, we used a Huawei E169 USB Dongle on the 3 mobile network, but the principles could easily be applied to any other Mobile Broadband dongle. Technical readers of this article could research the AT commands for their specific modem (although “AT+CSQ” command used below should work with most broadband dongles).

Using HyperTerminal to measure Signal Strength

We started by using the normal 5 reception bars in the “3Connect” connection manager software to measure reception, but it quickly became clear that this was not a very accurate way to measure reception.

So after some research and playing around, we figured out how to accurately measure reception by using AT commands with a Huawei E169 mobile broadband dongle.

We found out that all PC modems respond to “AT commands” – which “talk” to a modem directly. We used HyperTerminal to send AT commands directly to the modem – and obtain a more accurate reading of signal strength. The AT command we used was “AT+CSQ”, which should work with all USB broadband modems.

Here is the process we followed:

Step 1: Plug in your USB broadband modem

Give your computer 1 or 2 minutes to recognise the modem is attached.

Step 2: Launch HyperTerminal

Windows XP users can find HyperTerminal in Start > Programs > Accessories > Communication > HyperTerminal
Windows Vista users can download a free trial version of HyperTerminal here

Step 3: Configure HyperTerminal

Enter any name for the connection, e.g. “3G Modem” and select any icon.
On the “Connect To” screen, select your 3G modem in the “Connect using:” drop-down box.
Enter some dummy numbers into the “Area code” and “Phone number” boxes, and Press OK

Connect To Screen

On the next screen, select “Modify”, then on the “Settings” tab, select “ASCII Setup…”.
Tick the box next to “Echo typed characters locally” – this will help you see the commands as you type them.
Press OK twice and on the “Connect Screen” – do not click “Dial” – instead press “Cancel”

Step 4: Enter AT command to query Signal Strength

Type “AT+CSQ” and press return. You should see a response like this:

HyperTerminal Signal Strength

In the above example, the number 14 represents the measurement of signal strength.
You may re-enter this “AT+CSQ” command as many times as you like to check the measurement of signal strength. This number is explained below.
It is possible to measure only 3G/UMTS/HSDPA/HSUPA or only 2G/GSM/GPRS/EDGE. This can be done by sending specific AT commands to the USB modem – see the guide to AT commands below.

What do the numbers mean?

The number returned by the AT+CSQ command gives you a more accurate measurement of signal strength. The following table lists the dBm equivalent measurements (note that the dBm measurements are negative, so a higher negative number represents a lower signal strength):

0 < -113 dBm (Marginal)
1 -111 dBm (Marginal)
2 -109 dBm (Marginal)
3 -107 dBm (Marginal)
4 -105 dBm (Marginal)
5 -103 dBm (Marginal)
6 -101 dBm (Marginal)
7 -99 dBm (Marginal)
8 -97 dBm (Marginal)
9 -95 dBm (Marginal)
10 -93 dBm (Workable under most conditions)
11 -91 dBm (Workable under most conditions)
12 -89 dBm (Workable under most conditions)
13 -87 dBm (Workable under most conditions)
14 -85 dBm (Workable under most conditions)
15 -83 dBm (Good)
16 -81 dBm (Good)
17 -79 dBm (Good)
18 -77 dBm (Good)
19 -75 dBm (Good)
20 -73 dBm (Excellent)
21 -71 dBm (Excellent)
22 -69 dBm (Excellent)
23 -67 dBm (Excellent)
24 -65 dBm (Excellent)
25 -63 dBm (Excellent)
26 -61 dBm (Excellent)
27 -59 dBm (Excellent)
28 -57 dBm (Excellent)
29 -55 dBm (Excellent)
30 -53 dBm (Excellent)
31 > -51 dBm (Excellent)

So what do these numbers mean?

Marginal – Levels of -95dBm or lower. At these sort of levels, it is very likely that you may suffer low throughput and disconnects due to cell loading/breathing even with an outdoor antenna.
Workable under most conditions – Levels of -85dBm to -95dBm – Probably worth considering an outdoor gain type antenna. Could suffer poor throughput and disconnects due to cell loading/breathing.
Good – Levels between -75dBm and -85dBm – normally no problem holding a connection with this sort of level (even with cell breathing) without the use of an external antenna.
Excellent – levels above -75dBm. Should not be affected by cell breathing/loading and should not require an external antenna.

AT Command Reference for the Huawei E169 USB Bluetooth Dongle

We found the following model AT commands useful when testing signal strength with the Huawei E169 modem:

To get Signal Strength: AT+CSQ
Information: AT^SYSINFO
Set dongle to GPRS only mode: AT^SYSCFG=13,1,3FFFFFFF,2,4
Set dongle to 3G only mode: AT^SYSCFG=14,2,3FFFFFFF,2,4
Set dongle to GPRS preferred mode: AT^SYSCFG=2,1,3FFFFFFF,2,4
Set dongle to 3G preferred mode: AT^SYSCFG=2,2,3FFFFFFF,2,4

Signal Strength Test Variations

During our testing, we found that a number of factors can affect signal strength, for example:

Using an aerial / antenna – we obtained significant improvements by using either the Clip Antenna for Huawei USB Modems – CRC9 Connection or the Clip Antenna fro 3G USB Modems – Universal.
Interference from other electronic devices – e.g. WiFi on your laptop! We found that this interference can be reduced by using a USB extension lead to move your dongle away from from your PC/laptop.
Distance from network transmitter – We recommend using the OFCOM Sitefinder website to locate your nearest network transmitter. We obtained improvements by locating our antenna next to a window near to a transmitter.
Cell breathing – we noticed signal strength can increase and decrease “naturally” every few minutes – we understand that this could be attributable to “cell breathing” where the usage of network transmitters can have a positive or negative impact on signal strength.

Given the potential for significant variation in these factors, conducting testing to a high level of detail is quite difficult. However, despite the variation in factors, we definitely saw noticeable improvements in signal strength.

Broadband Dongle Clip Aerial for Laptop

Results of our tests

After several days of testing at our offices, we’ve been able to get improvements taking our signal strength from around -93Bm (10 on the scale) up to -77dBm (18 on the scale) – quite a significant improvement.

We found improvements can come from locating your laptop, dongle or dongle aerial near to a window. But this might not be practical for people in some situations.

But by far the most practical “instant” way to improve your mobile broadband reception is to plug in an antenna / aerial. In our tests, we’ve found that positioning an antenna carefully can increase reception by up to 20 dBm (network engineers call this a dBi measurement). We were particularly surprised by these results, given that the antenna we used was not expected to achieve such a large increase in signal strength. Therefore we suspect that the large increase can be explained by the combination of using an antenna, and the process of carefully positioning the antenna to optimise signal strength.

Recommendations for improving Mobile Broadband Reception

Read our guide: How to boost your Mobile Broadband Reception.
Give serious consideration to investing in a Mobile Broadband Dongle Antenna / Aerial – significant improvements in reception quality can be achieved.
If you feel confident enough to follow our guide above, try using HyperTerminal to measure your reception – it’s much more accurate than looking at the 5 reception bars on your broadband connection software.
Use a USB extension lead to move your Mobile Broadband dongle away from any interference coming from your Laptop / PC.
Find out where your nearest network transmitter is located (use the OFCOM Sitefinder website) – and then test how your reception changes as you position your dongle/antenna closer to the transmitter.

If time is precious and you’d rather not conduct signal strength tests – then it is definitely worth checking to see if you can get an improvement by using an antenna. But if you do have the time, you may be surprised how much improvement you can get by measuring signal strength and optimising the location of your broadband dongle (especially if you attach an antenna AND optimise the location of the antenna in relation to your nearest network transmitter).

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4 Comments

4 Comments so far

by Gerry Scales

On September 2, 2009 at 5:12 am

Anthony

Thanks for this excellent piece of work. I was struggling with getting Hyperterminal to work with my E169 until I found your guide.
I am in a poor reception area but unable to mount an external antenna. In what must seem like a strange move, I have mounted a Yagi indoors a few cm away from, and pointed at, a window. Using the RSSI numbers I have boosted the reported signal from 2 (-109 dBm) to 11 (-91 dBm).
I did this attached to a PC and then transferred the E169 to a wireless router.
My connection is now rock solid and I get quite acceptable performance (Download ~ 0.8Mbps, Upload ~ 0.2 Mbps) considering my poor location.
The biggest improvement has been in Upload speed. Together with QoS in the router, I hope that this will make it practical for occasional VoIP use.
I’d really like to know what difference the Yagi has made to the RSSI at the tower which I gather has a big impact on allocation of service during high loads.
My next step will be to try to read the RSSI while the E169 is still mounted in the router…

Thanks again – this has been a big help to me.

Gerry
by brian cornelius

On October 19, 2009 at 2:12 am

have followed instructions closely for setting up hyper terminal but cannot type command or anything in window ????
by Anthony

On October 19, 2009 at 2:10 pm

Brian

I suspect your problem is that the terminal is not set to echo your typed input to the local terminal. Check this part of Step 3:

“Tick the box next to “Echo typed characters locally” – this will help you see the commands as you type them.”

Hope that helps
by Dominic Oskis

On November 5, 2009 at 1:00 am

There are much better solutions than mucking about with Hyperterminal if you want to read the RSSI from a Huawei USB modem.

Realterm from realterm.sourceforge.net is a much more useful terminal program than Hyperterminal, it didnt take long to set it up to keep sending “AT+CSQ” to the modem every couple of seconds. It saves the fingers from dropping off. It soon became clear that the modems are very slow to report any change of signal strength, think 10-15 seconds!

I then discovered MDMA from http://www.nerve.org.za. Thats even more useful! It works fine with my E160 and E220 Huawei USB modems. You will need to close down any dialogue regarding the modems internal memory otherwise the com ports get blocked so MDMA wont be able to access the modem. It took me a good few minutes to figure that out!

You might also want to wander over to
http://www.sitefinder.ofcom.org.uk/ to find the nearset 3G base site of your network, it makes setting up directional antennas much easier.