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BTS told to change spectrum band in bid to end breakdowns

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BTS told to change spectrum band in bid to end breakdowns

By The Nation

 

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THE National Broadcasting and Telecommunications Commission (NBTC) has suggested that the Skytrain operator shift to another spectrum band for its signalling system as a long-term solution to the jams that have hit Bangkok’s Skytrain service 10 times within a single month.

 

A huge number of train commuters were stranded for four hours during rush hours on Monday and Tuesday, prompting a public outcry for the operator to fix the chronic problem.

 

The train operator, Bangkok Mass Transit System Public Company (BTSC), said its signalling system malfunctioned due to radio frequency jamming, as its 2400MHz spectrum experienced interference. The watchdog called in representatives of BTSC, Total Access Communication (DTAC) and TOT yesterday to seek ways to tackle the radio frequency interference problem that has hit the Skytrain service.

 

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NBTC secretary-general Takorn Tantasith said after the meeting that the problem was caused by the jam between the 2,300MHz spectrum band and the 2,400MHz band.

 

TOT has granted the 2310MHz-2370MHz range band to DTAC under partnership deals to provide broadband wireless service, while BTS has utilised the 2,400MHz band to manage its train operation. Though the gap between the TOT band and that of BTS is 30MHz, jams can sometimes occur.

 

The NBTC has recommended that BTS train system shift to use the 2480MHz-2495MHz frequency in order to solve the problem in the long run and that TOT switch off a number of the 2300MHz cellular base stations along the Skytrain routes on a temporary basis until BTS finishes implementing the change, Takorn added.

 

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Surapong Laoha-Unya, executive director of BTS Group Holdings, said that BTS planned to finish installing related signal-receiving equipment and signal filters and move to the new band tomorrow. He believes that the BTS will be able to offer normal service as usual from Saturday. A TOT representative said that TOT would work with BTS to solve this problem.

 

Narupon Rattanasamaharn, DTAC’s senior vice president, Head of Regulatory Division, said he believes that DTAC’s existing 2300MHz customers would not be affected by the temporary shutdown of the 2300MHz base stations, as their cellphone devices would automatically switch to the company’s 1800MHz and 2100MHz frequencies during the period.

 

Source: http://www.nationmultimedia.com/detail/business/30348775

 
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-- © Copyright The Nation 2018-06-28

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4 hours ago, webfact said:

THE National Broadcasting and Telecommunications Commission (NBTC) has suggested that the Skytrain operator shift to another spectrum band

I doubt that it is a polite suggestion. More like a do it - or else suggestion. PM Prayut has only been back in town 5 minutes and he already has his boys at the NBTC on the job with a solution in hand. What would we all do without him? Besides, unhappy commuters might cost him votes.

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I don't understand what changed to suddenly make this a major problem? Haven't they both been using their respective frequencies for quite some time already?

 

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A best practice from other countries is to create a protected bandwidth for certain Civil, and essential Metropolitan Utilities. This means that nobody can encroach upon those specific frequencies, or can only have an output of .5 Watts of transmitting power.

 

In the interim BTS could crank up their power amplification... this would overpower the other frequencies stepping on them.

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6 hours ago, webfact said:

TOT has granted the 2310MHz-2370MHz range band to DTAC under partnership deals to provide broadband wireless service, 

 

But probably DTAC has bought cheap 2400 equipment from India? 

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Unfortunately I suspect that this would not be a quick fix, as every WLAN device on the whole network would either have to be replaced or if possible reprogrammed to accommodate a new frequency.

This would be in the hundreds.

Theoretically, if the DTAC transmitters were bleeding over to the BTS system, then they should also have been interfering with WiFi networks in the same areas.

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2 hours ago, Peabody said:

I don't understand what changed to suddenly make this a major problem? Haven't they both been using their respective frequencies for quite some time already?

 

According to a NBTC spokesman, the BTS has been using that spectrum illegally for around ten years so they should not be complaining and should move to a licensed frequency as assigned by the NBTC.

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11 minutes ago, PETERTHEEATER said:

According to a NBTC spokesman, the BTS has been using that spectrum illegally for around ten years so they should not be complaining and should move to a licensed frequency as assigned by the NBTC.

Which, unfortunately, just goes to show how much NTBC knows about the system in use here and worldwide!

There is no way on this planet that NBTC would allow the importation of equipment that transmits or receives on illegal or unlicensed frequencies, they are anal about such things, even a tad uneducated and old fashioned.

 

The BTS uses a CBTC system supplied by Bombardier, lots of their systems in use worldwide and nearly all CBTC systems use the publicly available, perfectly legal 2.4GHz WiFi frequencies that you, myself and every other Tom, Dick and Harry use, as it licensed for exactly this.

https://en.wikipedia.org/wiki/Communications-based_train_control

https://www.bombardier.com/en/transportation/projects/project.cityflo-bangkok-thailand.html

https://www.bombardier.com/en/transportation/products-services/rail-control-solutions/mass-transit-solutions/cityflo-450.html

 

In reality there has been a lot of research and talk about dedicated frequencies for CBTC, especially where it is safety dependent.

 

FYI the MRT use the cityflo-650, doubtless using the same frequency.

 

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My comms man informs me that the shift to the other end of the 2.4GHz band has been completed.

 

We await the wheel to come off tomorrow when DTAC turn their towers back on.

 

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