4G black spots: Third of mobile internet tasks attempted on trains fail


Despite improvements to mobile internet access, commuters in the UK are still being hit by black spots that prevent them from carrying out tasks on the internet while on the move, according to new research.


The connectivity study, from by Global Wireless Solutions (GWS), found that Three is the best network for voice, Vodafone for 3G, and EE for commuters on 4G, following most rigorous train connectivity study ever conducted.

Key findings include:

• 1 in 3 mobile internet tasks and 1 in 7 voice calls attempted on commuter train routes failed during testing

• Three has best network for commuters who like to talk

• Vodafone’s subscribers get best 3G data service, EE subscribers best 4G data service…

• …but EE, O2, and Vodafone all heavily relying on their older 2G networks to cover commuters

• St. Pancras wins mobile connectivity wooden spoon

GWS engineers carried out high-level tests while travelling back and forth on the ten most popular commuting routes into and out of London, and discovered that—on average—almost 1 in 4 3G data ‘packets’ (23.2%), and well over 1 in 3 4G data packets (37.2%) travelling across the networks of the four major UK operators didn’t make it to their intended destinations.

Figure 1: Packet data reliability: the big four operators on 3G and 4G


GWS’ testing suggests that Vodafone subscribers get the best 3G data service while commuting – Vodafone’s 3G network is the most reliable (in terms of getting data packets through) and offers the fastest download speeds (2Mbps on average during testing).

EE currently offers the best 4G data service; its 4G network tied with Vodafone in the reliability stakes but was the fastest when it came to downloads (5.6Mbps on average during testing).

Figure 2: how long it is likely to take commuters with 3G data to upload a picture/download a song/download a video?


Figure 3: how long it is likely to take commuters with 4G data to upload a picture/download a song/download a video?


Every carriage is a quiet carriage now

GWS’ testing suggests that it’s not just the mobile internet that Londoners struggle to use while commuting: 1 in 7 voice calls (14%) made from trains fail too.

Three won GWS’ voice calling run-off; its network was the joint-first-most reliable, but emerged as the clear winner when call quality was factored in.

Commuters are likely to experience poor call quality (e.g. sound breaking up) when mobile operators use older 2G networks to route their calls, and/or use ‘half-rate codecs’ to decode voice call data.

GWS’ engineers were ‘on 2G’ with O2 for more than 60% of the time while testing on commuter trains. In addition, O2 used half-rate codecs to handle almost a third of all the calls (28.16%) engineers made during the testing programme.

EE fell back on its 2G network two-fifths of the time (41.82%) during testing, but only used half-rate codecs to decode 2.96% of the test calls made.

Vodafone also relied on its 2G network 40% of the time during testing; it used half-rate codecs to decode 7.92% of all the calls made by engineers in the course of the testing programme.

No signal on the Hogwarts Express

1 in 4 of the data task failures (24.18%) GWS’ engineers experienced occurred while they were on trains in stations, while 1 in 5 occurred when they were on trains on open stretches of track.

However, voice calls are more likely to fail on open track than in a station (1 in 4 of the voice ‘failures’ GWS’ engineers experienced occurred when they were in a station, compared to 1 in 3 when they were on open track).

GWS found that voice and data failures are more likely to occur when a train is travelling from 0-5 MPH than when it is travelling between speeds of 5 and 50 MPH. Failures are most likely to occur when a train is travelling above 50 MPH.

St. Pancras has by far and away the worst connectivity of all of the stations tested by GWS. GWS’ engineers experienced an average of 99 voice and packet data failures (across the four operators) while testing in the famous station.

Figure 4: Top 10 worst-connected commuter stations


Paul Carter, CEO of GWS, commented: “Leaves on the track, the wrong kind of snow, having to stand up all the way to work and back – commuters have enough to contend with without the kind of mobile connectivity problems we’re revealing today. It’s hard to believe we’re in 2014 and in a situation whereby a trained wizard would have a tough time getting a signal on the Hogwarts Express while it’s sitting in St. Pancras.”

“Pressure from commuters makes it inevitable that trains won’t keep their status as mobile dead zones for much longer. It’d be great to see networks, rail operators and station-masters taking the lead on improving connectivity for commuters – rather than having to be dragged into the 21st Century kicking and screaming.”


GWS’ engineers benchmarked the ten most popular commuter train routes into and out of London, and used an array of 12 Samsung Galaxy S4s (powered by Rohde & Schwarz’s SwissQual QualiPoc Freerider) to gather data for its study of commuters’ mobile connectivity. Three SIMs from each of the four major UK operators (3, EE, O2 and Vodafone) were used during testing – in each case one SIM was used for voice testing, one SIM was used for 3G-only data testing, and one SIM was used for 4G-only data testing. An extremely wide range of voice and data metrics were analysed during the study of commuters’ connectivity experiences; a specific rundown of these metrics is available on demand. The figures posted have been weighted and stat-tested. Testing was conducted in June 2014.

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