q
Deploying technologies that have
higher spectral efficiency.
q Adapting specifications to enable operation
of UMTS-HSPA and LTE in all available
bands.
q Designing both
FDD and TDD versions of technology to take advantage of both paired and
unpaired bands.
q Designing
carrier aggregation techniques in HSPA+ and LTE-Advanced that bond together
multiple radio channels (both intra- and inter-frequency bands) to improve peak
data rates and efficiency.
q
Deploying as many new cells (large
and small) as is economically feasible.
Although all of these industry initiatives greatly expand capacity, they do not obviate the need for additional spectrum.
The FCC released a report in October 2010 that projected U.S. spectrum requirements19 and concluded that 275 MHz of additional spectrum would be needed within five years and 500 MHz of additional spectrum within 10 years. This forecast assumes ongoing increases in spectral efficiency from improving technologies.
An important aspect of UMTS-HSPA and LTE deployment is for infrastructure and mobile devices to accommodate the expanding number of available radio bands. The fundamental system design and networking protocols remain the same for each band; only the frequency- dependent portions of the radios must change. As other frequency bands become available for deployment, standards bodies adapt UMTS-HSPA and LTE for these bands as well.
In 2012, the FCC changed the rules on the Wireless Communications Service (WCS) band, which constitutes 30 MHz of spectrum at 2.3 GHz, making 20 MHz available for mobile broadband.20
The forthcoming 2.6 GHz frequency band in Europe, Asia, Latin America, and other parts of the world will also be a common band for LTE deployment. Unfortunately, different band plans in different parts of the world will complicate roaming on this band. Globally, operators are also refarming spectrum by limiting the spectrum used for 2G (cellular and Personal Communications Service [PCS] bands) to create space for 3G and 4G deployments.
Recently, the FCC repurposed 40 MHz of Mobile Satellite Services (MSS) spectrum for terrestrial use in what it termed the “AWS-4 band.”
Unfortunately, the process of identifying new spectrum and making it available for the industry is a lengthy one, as shown in Figure 1.
Figure 1: Spectrum Acquisition Time
The biggest opportunity areas for new spectrum in the United States
currently are incentive auctions of TV-broadcasting spectrum at 600
MHz, government spectrum from 1755 to 1850 MHz and 1695 to 1710 MHz managed by the
National Telecommunications and Information Administration (NTIA) to be auctioned as
part of AWS-3, and
the proposed “small-cell” band from 3550 to 3650
MHz and its possible extension to 3700 MHz.
In June 2013, the Obama Administration announced new Administration
spectrum initiatives, including directing Federal agencies to
enhance the efficiency of their spectrum use, making greater capacity
available for commercial networks, and funding
research into spectrum sharing.
Table 1: United States Current
and Future Spectrum Allocations
|
Frequency Band
|
Amount of Spectrum
|
Comments
|
|
700 MHz
|
70 MHz
|
Ultra-High
Frequency (UHF)
|
|
850 MHz
|
64 MHz
|
Cellular and
Specialized Mobile Radio
|
|
1.7/2.1 GHz
|
90 MHz
|
Advanced
Wireless Services (AWS)-1
|
|
1.9 GHz
|
140 MHz
|
Personal
Communications Service (PCS)
|
|
2000 to 2020,
2180 to 2200
MHz
|
40 MHz
|
AWS-4
(Previously Mobile Satellite Service)
|
|
2.3 GHz
|
20 MHz
|
Wireless
Communications Service (WCS)
|
|
2.5 GHz
|
194 MHz
|
Broadband
Radio Service (Closer to 160 MHz deployable.)
|
|
|
FUTURE
|
|
|
600 MHz
|
Up to 120 MHz
|
Incentive auctions
|
|
1695-1710
and 1755 to
1780 MHz.
|
65 MHz
|
AWS-3. 1755
to 1780 MHz to be combined with 2155
to 2180 MHz. Spectrum sharing.
|
|
3.55
to 3.70 GHz
|
100 or 150 MHz
|
Small-cell
band with spectrum sharing
|
|
Above 5 GHz
|
Multi GHz
|
Anticipated
for 5G systems in 2020 or later timeframe
|
