The Radio Frequency Agency of the Ministry of Information and Communication (MIC) has received more than 50 complaints since May 2015 about network interference from Viettel, MobiFone and VinaPhone, the three largest mobile networks in Vietnam. 

The interference occurred on 900MHz, 1800MHz and 2100MHz frequency bands which the MIC had reserved for 2G and 3G networks. 

The affected areas included the districts of Ba Dinh, Hoan Kiem, Hai Ba Trung, Cau Giay and Thanh Xuan in Hanoi.

The jam seriously affected the quality of services provided by network operators, causing an abnormally high percentage of unsuccessful calls, connection speed decline and 3G disconnections.

The agency, after taking a probe, found that the problem was due to signal amplifiers which did not meet required technical standards.

In some areas in Hanoi, where the mobile signal is weak, some households and individuals used repeaters to amplify signals to improve the situation.

The amplifiers can be bought easily in the market or via internet.

However, most of them cannot satisfy Vietnamese standards, thus causing harmful interference to mobile networks.

The investigators have also found that some businesses used RFID (radio frequency identification) devices in the management of their vehicle parking services, goods and container management at ports, library and storehouse management and other works.

The devices could also cause interference because they used frequency bands which were not reserved for them and could not satisfy requirements stipulated in MIC’s Circular No 03 dated March 2012.

According to Le Dang Dung, deputy general director of Viettel, the use of incompatible devices is a big problem for the 3G network.

In May 2015, Viettel discovered 53 sources of jams in the inner districts of Hanoi. To date, 23 sources have been settled, while the other 27 have not been found. The remaining three refused to cooperate with Viettel.

According to Le Van Tuan, deputy director of the Radio Frequency Agency, it is difficult for the frequency management unit to find and settle jam causing sources.

The devices can be brought to Vietnam legally, and have been used widely by people.

Tuan complained that the loose management over the import of wireless devices is a threat to telecommunication network safety.

In principle, inspectors can impose fines on the devices’ users. However, users said they have to use the amplifiers to improve weak signals. They do not know that devices with North American standards are incompatible with other devices in Vietnam.

Vietnam Net