GSM 400 Spectrum

A new GSM 400 Mhz frequency band is now being standardised by the European Telecommunications Standards Institute (ETSI). 

In April 1998 a Digital Interest Group (DIG) was formed to investigate the migration options open to NMT 450 operators. 

During 1998, the DIG prepared a detailed Requirement Specification with which vendors could comply. 

The DIG group investigated three possible technologies as potential digital versions of NMT and, in October 1999, the results of the investigations were presented with the majority of the NMT MoU operators expressing their preference for the GSM 400 solution. 

 GSM 400 is a band that brings access to this world-leading standard for NMT 450 operators, as well as offering a coverage bonus effect to current GSM operators worldwide. GSM 400 will evolve with the core GSM specification and will include seamless roaming with other GSM bands.

Technically, GSM 400 and NMT 450 can run in parallel on the 450MHz band. 

This will be the standard process that many operators follow during the migration from NMT to GSM.

In the long run, however, the limited availability of spectrum frequency in most countries will make running both networks on a long-term basis impractical, since all capacity available will be required to run a full service.

As a result, operators will eventually need to close down their 450 networks to run GSM 400 networks successfully.


The introduction of the new 400 MHz frequency band will further leverage the success of global GSM, which so far has been established through the current 900MHz, 1800MHz and 1900MHz bands.


ETSI will release a GSM 400 specification as part of its ETSI/SMG GSM99 specification. GSM 400 is expected to become commercially available during 2001.
The entire switching platform and base station controller infrastructure will remain static when new frequency capabilities are included. 


However, new software will be required in some network elements. Nokia and Ericsson have proposed that GSM 400 is be standardised in ETSI as a part of the GSM standard which is available to all manufacturers on an equal basis. 


As a result of this GSM 400 will form part of the existing GSM standard, which is continuously evolving as per GSM standard (900/1800). This evolution results in a phased approach toward IMT-2000 service requirements. 

The commitment of Nokia and Ericsson to the development of GSM 400 is illustrated in the fact that they have already made the first official GSM 400 call at the GSM 400 Conference in Budapest, Hungary in September 1999. 


Both Nokia and Ericsson supplied prototype equipment to make the call possible. The prototype equipment included GSM400/1800 dualband phones, Radio Base Station and Base Station Controllers.


Prototypes of tri-band GSM 400/900/1800 handsets with HSCSD and WAP support will begin trials in the fourth quarter of 2000 and are expected to be available in commercial volumes in 2Q / 2001. Network infrastructure trials are planned for 4Q / 2000 with commercial availability from 1Q / 2001

GSM 400 Technical Details
Frequency Allocation GSM 450 Band:
450.4 - 457.6 MHz uplink
460.4 - 467.6 MHz downlink
GSM 480 Band (ext.):
478.8 - 486 MHz uplink
488.8 - 496 MHz downlink
Frequency Spectrum: 7 MHz
Duplex Seperation: 10 MHz
Carrier Spacing: 200 kHz
Coverage, Extended Range: Up to 120km
  • Supports fragmented usage of the frequency band
    [MT450 frequency variants]
  • Down-banded GSM - same features, services and evolution

Coverage:

Operation in the 400MHz band offers an advantage in coverage over other systems operating in higher frequencies, as a signal attenuates less at lower frequencies. This means less investment costs for the operator, as fewer cell sites are required to cover rural and coastal areas and highways. With its inherent better propagation characteristics, GSM 400 offers more efficient coverage than the higher frequency variants of GSM. This means that operators need to deploy fewer sites; GSM 400 covers the same area as GSM 1800 with a fifth of the number of sites and the same area as GSM 900 with half the amount of sites. The potential cell range is up to 120 km. Furthermore, where a GSM network infrastructure already exists, much of it can be reused by GSM 400, reducing network investment costs further.


The radio coverage area for a GSM 400 BTS site will exceed the radio cover provided by both GSM900 BTS and GSM 1800 BTS sites. Due to the predicted radio coverage that will be available with the implementation of GSM 400 radio site, the extended cell feature will be an integral part of the new frequency. 

The maximum range achievable with the extended cell feature will be approximately 67 Km. A proposal has been submitted for the enhancement of the extended cell feature to accommodate ranges of between 70 to 140 km. 

The increased coverage area will give the GSM 400 operators an advantage in the implementation and penetration of high-speed data, which forms part of the GSM data evolution. 

Capacity:

 

GSM 400 will support all the ETSI standardized capacity enhancing features presently being supported by GSM900/1800 

  • Frequency hopping

  • Discontinuous Transmission

  • MS and BTS Power Control

  • Adaptive Multirate 

GSM 400's requirement for fewer base stations  reduces installation time, which in turn leads to reduced time-to-market, enabling new operators to start earning revenue and capture market share more quickly. The increased coverage is also more attractive to users, which both encourages further subscribers to sign up and increases loyalty among existing subscribers.