Spectrum re-farming will play a key role in LTE deployments

7 July 2011

The challenge for next-generation '4G' services is to identify globally harmonized spectrum, as currently LTE is being required to provide operators with multiple options in terms of channel size and spectrum band, as well as a choice between FDD and TDD modes.

But the reality is that spectrum fragmentation is likely to remain an issue globally.

Based on detailed country-by-country research, Informa Telecoms has asked some key questions about spectrum licensing and its likely take-up by region and country through to 2016.

Crucially it asks key questions such as: What are the advantages and disadvantages of the emerging core bands for LTE? What are the key differences between FDD and TDD spectrum? What are the early experiences of LTE rollouts in the more popular bands? What will be the impact of the proliferation of spectrum bands for LTE on the supply chain? Why fragmentation needs to be avoided. And more!

Julian Bright, Senior Analayst at Informa, writes:

"As well as deploying LTE in newly-licensed bands such as 700MHz, 800MHz and 2600MHz, many operators are looking to free up capacity in existing bands that are currently home to legacy services such as GSM or UMTS. These include the 900MHz, 1800MHz and 2100MHz bands. Use of these bands often involves the re-farming of some or all of the existing, legacy services to alternative bands in order to free up spectrum for LTE.

The 1800MHz band in particular is gaining a lot of attention, and there are some markets where operators have already been apportioned large amounts of spectrum in this band. However, it is unevenly distributed in others and can be fragmented, or yet to be licensed. While some operators support the use of 900MHz for LTE, others regard it as being more appropriate for use as a UMTS coverage band.

Use of the 2100MHz band for LTE is being championed by Japan's NTT DoCoMo, but its global appeal appears to be limited. In addition to seeking new spectrum in which to deploy LTE, operators are increasingly looking to existing bands as a means of supplementing coverage and capacity. One approach is to free up spectrum in bands that are already used for other services, such as GSM and UMTS/HSPA, by re-farming these existing bands.

The three main candidate bands for re-farming in most regions of the world are the 900MHz, 1800MHz and 2100MHz bands, currently used for either GSM or UMTS/HSPA. In North America, the bands at 800MHz, 850MHz and 1900MHz, presently supporting services such as iDEN and CDMA, can also potentially be re-purposed to support LTE in the future.

Whilst the bulk of available spectrum for LTE lies at 1800MHz and above, as is the case in Europe, it is generally accepted that for wide-area coverage of mobile broadband services, the lower bands in the 800MHz to 900MHz range are the most attractive (see fig. 1). However, the indications from Informa's research are that, of all the candidate bands for re-farming, the 900MHz band is likely to see the lowest level of LTE deployments worldwide, representing just 3% of the global addressable market for LTE by 2016.

Fig. 1: European mobile spectrum by band

Potentially more accessible as users migrate from 2G services to 3G, the 900MHz band has been proposed as an option for operators wanting to run LTE alongside GSM until such time as the 2G network can be shut down. In the interim, the use of adaptive multi-rate speech codecs and associated techniques to increase the performance and spectral efficiency of existing GSM/EDGE services can increase capacity.

However, those operators that have already re-farmed their spectrum in the 900MHz band have generally preferred to do so in order to extend coverage of UMTS/HSPA. These include Finland's Elisa, operators in Australia that are using UMTS900 for regional coverage to supplement UMTS at 2100MHz, and operators in France where UMTS900 is being rolled out to cover 98% of the population.

UK operator O2 started using the 900MHz band for 3G services in March. The operator has switched to the UMTS900 network in London, saying it would....

< ...more... >