BUCHAREST, Romania-Due to the analog transmission and the lack of value-added services, NMT 400 systems in Eastern Europe-which enjoyed great success during the last two decades-have suffered in recent years. A great number of NMT 400 customers have evolved to GSM systems, and NMT operators face the threat of having their networks shut off.
These issues have forced operators to focus on digital transition strategies.
NMT systems operate in two different radio bands-450 MHz and 900 MHz. NMT 450 is also further divided in two systems: NMT 450 and NMT 450i (i representing improved).
The benefits of NMT 450 and 900 include good coverage in urban and rural environments and high-quality voice service. On the other hand, NMT terminals are expensive and heavy, and carriers cannot offer many value-added services.
The Digital Interest Group of the NMT Memorandum of Understanding (MoU) operators met last October in St. Petersburg, Russia, to discuss a digital migration solution. In April, Eastern European NMT carriers met in Prague, Czech Republic, to further discuss issues surrounding digital migration of their networks.
The NMT MoU concluded NMT operators should designate U.S.-developed CDMA, Europe’s GSM standard or Digital-NMT for digital migration. D-NMT lacks roaming capabilities among numerous mobile networks, putting it at a disadvantage as a migration technology. CDMA technology has an uphill fight against the well-established European GSM systems, although both technologies are being trialed by Eastern European NMT carriers.
Hungary’s Westel 450 announced a trial of CDMA 450 technology with Lucent Technologies and Qualcomm will begin in September. The first phase of the trial will focus on RF optimization and maximizing coverage. CDMA also is present in Romanian and Russian wireless local loop networks.
“We chose Lucent because we truly believe in the success of the CDMA 450 idea, and Lucent is a strong supporter of this system,” said Istv n G lfi, Westel 450 technical director. “CDMA is a very competitive technology in our 2G TDMA (GSM) environment and provides a very efficient exploitation of the 450 MHz spectrum, high data rates, and it is future proof, fully 3G compatible.”
Most other NMT MoU operators are moving forward with GSM 400 migration plans. In particular, Russian operator Moscow Cellular Communications chose GSM 400, and the first GSM 400 call was made last September in Budapest, Hungary.
GSM 400 will enable GSM systems to be integrated with existing NMT 450 and NMT 450i networks. One feature offered by GSM 400 is the potential for roaming among the different GSM frequencies: 400 MHz, 900 MHz, 1800 MHz and 1900 MHz.
“That will be limited just by the handsets’ band capabilities offered by manufacturers,” said Petri Nyberg, NMT MoU secretary.
Other features will be similar to current services and data speeds.
Another benefit touted by GSM vendors is only the base station hardware must be upgraded, while other network equipment, such as the switching platform and antenna sites, will not have to be replaced.
The new technology will support all European Telecommunications Standards Institute standardized capacity-enhancing features supported by the GSM 900 standards. GSM 400’s extended cell feature will be an integral part of the new networks. In principle, GSM coverage is limited to 35 kilometers in normal cases, regardless of frequency, but GSM 400’s extended cell feature can increase this coverage. But the extended coverage does not work with higher data speeds like 43.2 kilobits per second.
