Required Advances in Microwave
Devices and Components to Meet the
Needs of Future Wireless
Telecommunication Systems
Michael J. Marcus
mjmarcus@alum.mit.edu
QuickTime™ an d a
TIFF (LZW) decompressor
are need ed to see this p icture .
Qui ckTi me™ and a
TIFF (Uncompressed) d ecompresso r
are ne ede d to see thi s pi cture.
Associate Chief for Technology Visiting Researcher
Office of Engineering and Technology École nationale supérieure
Federal Communications Commission des télécommunications
Until March 31, 2004 QuickTime™ and a After 5 April 2004
TIFF (Un compressed) decompressor
are neede d to see this picture.
IMS 2004 Plenary
1
Outline
I. Long Term Trends in RF Technology
that Impact Spectrum Policy
II. Long Term Trends in Spectrum Policy
that Impact RF Technology
III. Getting to Higher Efficiency
IMS 2004 Plenary
2
1st Law of Spectrum Use
• If spectrum free and efficient technology
has a cost, the rational designer plans
systems that use much spectrum and
use minimally efficient technology
• This is the basic problem in spectrum
management and a major disincentive
to efficient technology
IMS 2004 Plenary
3
I. Long Term Trends in RF Technology that Impact Spectrum Policy
Military/Civil Relationship
• Military R&D historically has had a huge
impact on advancing available civil spectrum
technology
– Moving the “frequency frontier” transition higher
– Introducing component technology that enables
new applications
– Pioneering software/cognitive radio
• Trend is now bilateral
– Some civil markets for advanced technology
exceed military market
– COTS trend
IMS 2004 Plenary
4
I. Long Term Trends in RF Technology that Impact Spectrum Policy
Technical Trends
• Increasing upper frequency limit
– 2 GHz cells phones and 1.5 GHz GPS are
common pocket-sized consumer items
– 12 GHz satellite TV is a common Qui ckTi me™ and a
TIFF (Uncompresse d) de comp re ssor
are ne eded to see th is pi cture.
consumer item
– Commercial equipment now available at
64 GHz
Qu ic kTime ™ a nd a
TIFF (Unco mpres sed ) de co mpress or
are ne ed ed to se e th is p ic ture.
• Most RF equipment now contains
microprocessors and much memory
– But generally software is fixed at time of
manufacture and is not cognitive
IMS 2004 Plenary
5
I. Long Term Trends in RF Technology that Impact Spectrum Policy
Spectrum Usage
• Spectrum use increasing due to
– Increasing mobility in society
– Demand for quick access to information
– Decreasing equipment and service costs
• No significant new “green field”
spectrum below millimeterwave
• Incumbents all claim heavy use of
spectrum and need for more!
IMS 2004 Plenary
6
I. Long Term Trends in RF Technology that Impact Spectrum Policy
Spectrum Usage
• Tatemae (Appearance) • Honne (A more objective reality)
Time
Frequency
At a given location and time, there is often a lot of unused
spectrum - which can not be used due to both existing spectrum
policies and fielded technologies
IMS 2004 Plenary
7
I. Long Term Trends in RF Technology that Impact Spectrum Policy
Military Spectrum Use •Military spectrum
use has a
generally negative
spatial correlation
with civil spectrum
use
–San Diego is a
QuickTime™ an d a
TIFF (LZW) decomp resso r
notable exception
–Civil spectrum
are need ed to see this picture.
congestion
mainly an issue in
top 10-20
markets although
other inequities
exist in rural
IMS 2004 Plenary http://www.cr.nps.gov/nagpra/DOCUMENTS/BasesMilitaryMAP.htm areas 8
I. Long Term Trends in RF Technology that Impact Spectrum Policy
Public Safety Spectrum
• Public safety communications has a
very high societal value and traditionally
has been given top priority in spectrum
access
• But much PS communications also has
a high peak-to-average ratio
• Is sizing spectrum assignments to
peaks the only feasible alternative?
IMS 2004 Plenary
9
II. Long Term Trends in Spectrum Policy that Impact RF Technology
Deregulation
• Since the late 1970s the FCC has
generally followed a bipartisan
approach of deregulation in spectrum
policies and has been a world leader in
this direction
IMS 2004 Plenary
10
II. Long Term Trends in Spectrum Policy that Impact RF Technology
Auctions
– FCC economists successfully argued that
maximizing revenue required maximum
technical flexibility for licensees
• Spectrum that has been auctioned generally
has more flexibility than other spectrum
• Key difference with European auctions
• Creates a market driven, potentially fast
approach for new technologies and services
to obtain spectrum
IMS 2004 Plenary
11
II. Long Term Trends in Spectrum Policy that Impact RF Technology
Local Regulatory Issues
We would like antennas
to fit into their environment
But we often get systems that look
like they were designed by …
engineers
This is what is often blocking rollout of new technologies!
IMS 2004 Plenary
12
II. Long Term Trends in Spectrum Policy that Impact RF Technology
Local Regulatory Issues
• Most innovative efficient radio technologies
need antenna sites on grids of 1-5 km
– Earlier systems generally used a small number of
high antennas, e.g. broadcasting, police
• FCC actions could result in perhaps 10
independent mobile systems and 10 fixed
wireless access systems in every area - each
with multiple antenna site requirements
• Is this practical in the present environment?
IMS 2004 Plenary
13
III. Meeting Future Needs
Shopping List
• Modulation
• Spatial architecture
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
• Antenna technology
• Cognitive radio/
spectrum access
• Device technology QuickTime™ and a
TIFF (Uncompressed) decompr
are neede d to see this pictur
IMS 2004 Plenary
14
III. Meeting Future Needs
Modulation
• Modulation/coding efficiency was low in
civil systems in the past but is rapidly
approaching practical limits so order of
magnitude gains are unlikely
IMS 2004 Plenary
15
III. Meeting Future Needs
Spatial Architecture
• Cellular architecture is now widespread in
many applications
– But intensity of cell splitting rarely approaches
what is routine in Japan
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
– Not a breakthrough technology but requires
careful engineering and propagation modeling
IMS 2004 Plenary
16
III. Meeting Future Needs
Antenna Technology
QuickTime™ and a
“Plastics”
TIFF (Uncompressed) decompressor
are neede d to see this picture.
“Antennas”
IMS 2004 Plenary
17
III. Meeting Future Needs
Antenna Technology
• Antenna technology has generally been
underutilized as efficiency tool and probably
offers more opportunities for DARPA-style
quantum improvements than most other
technologies
– Some use of adaptive array antennas in WiFi and
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
TDD cellular
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
– Great potential for MIMO/STC/BLAST if it can be
reduced to practice
• “Trading megaflops for MHz”
IMS 2004 Plenary
18
III. Meeting Future Needs
Antenna Technology
• Stealth aircraft technology resulted from an
innovative collaboration of EM and
aeronautical engineers to build an aircraft
that could fly well and have low radar cross
section
QuickTime™ an d a
TIFF (Uncompressed) decompressor
are need ed to see this p icture .
IMS 2004 Plenary
19
III. Meeting Future Needs
Antenna Technology
• We urgently need a similar collaboration
between EM/antenna specialists and
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture. architects/city planners to define new
types of antenna systems that can
support multiple RF systems and be
more compatible with suburban
environments
– Or else …
IMS 2004 Plenary
20
III. Meeting Future Needs
Antenna Technology
• A key issue in real spectrum
management applications is often signal
rejection of receivers in nearby bands
– Key issue in both Nextel and Northpoint
problems/nightmares
• Good design of vertical pattern of
antennas can limit dynamic range of
signals near antenna sites
IMS 2004 Plenary
21
III. Meeting Future Needs
csc 2 Antenna Technology
• Cosecant squared antenna technology
has great potential to reduce real
practical limits to efficiency at UHF and
above
– csc2 technology, developed at WWII MIT
Rad Lab, results in relatively uniform pfd
over a large area vice large dynamic range
with traditional antennas
IMS 2004 Plenary
22
III. Meeting Future Needs
csc 2 Antenna Technology
• csc2 technology is practical at
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture. f > 1 GHz and could be used
productively in many applications to
improve spectrum efficiency
• Few products available at present
QuickTime™ and a
QuickTime™ and a TIFF (LZW) deco mpressor
TIFF (LZW) decompressor are neede d to se e this picture.
are needed to see this picture.
IMS 2004 Plenary www.remec.com/pdfs/LMDS%20ShapeBeam.pdf 23
III. Meeting Future Needs
Spectrum Access
• There is “green field” spectrum in mmW
region, but
– It is very different in nature than lower
bands due to both line of sight and
absorption issues
– Can be useful in certain specialized
applications especially if dual use can be
made of DoD-funded components
• DoD spectrum managers do not recognize dual
use as a beneficial goal, though
IMS 2004 Plenary
24
Check with previous
III. Meeting Future Needs
Spectrum Access
– Suggest industry and DoD spectrum
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
managers enter into a dialogue on what
role “dual use” has in military spectrum
policy
IMS 2004 Plenary
25
III. Meeting Future Needs
Spectrum Access
• Reallocation of federal spectrum has
been helpful in the past, but unlikely in
current homeland security focus
regardless of merits
• So let’s make use use of the
spectrum that is there and is actually
underutilized without changing
allocation!
IMS 2004 Plenary
26
III. Meeting Future Needs
Spectrum Access
• New technology is needed to enable near
QuickTime™ and a
TIFF (Uncompressed) decompressor
real time secondary spectrum markets
are needed to see this picture.
permitted by present FCC rules
• Need an automated spot market and
electronic clearing house to allow low
transaction costs for short leases
– In applications involving base stations, base
station technology must adapt to secondary
market
IMS 2004 Plenary
27
III. Meeting Future Needs
Cognitive Radio *
• Cognitive radio is a family of techniques that
generally use software defined radio
technology to access spectrum more
efficiently - other likely area for
quantum increase QuickTime™ and a
TIFF (Uncompressed) decompre ssor
• DARPA XG program is a key
are neede d to see this picture.
program in this area
• FCC is very interested in both dynamic
frequency selection/DFS and “interruptible
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
spectrum”
*Note that DARPA and FCC use the jargon “cognitive radio”
somewhat differently
IMS 2004 Plenary
28
III. Meeting Future Needs
“Interruptible spectrum”
• “Interruptible spectrum” has been
proposed by FCC to enable leasing of
public safety spectrum subject to
“ruthless preemption”
– Just as there is a real market for
interruptible electricity, there can be a real
market for interruptible spectrum
• Comm engineers create useful systems our of
less than ideal channels
IMS 2004 Plenary
29
III. Meeting Future Needs
“Interruptible spectrum”
• Need preemption mechanism that is
both fail/safe and easy to
explain/demonstrate to public safety
users who much have confidence in it
• Need new nonPS systems that can
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
integrate normal spectrum and
interruptible spectrum
IMS 2004 Plenary
30
III. Meeting Future Needs
Device Technology
• Receiver front end devices
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
– Decrease IM problems that impact spectrum
efficiency
– Or DSP technology to do the same
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
• Duplexer technology to decrease IM products
• Affordable mmW devices
QuickTime™ and a
– Low power semiconductor devices
TIFF (Uncompressed) decompressor
– TWT multiwatt devices
are needed to see this picture.
– Hopefully these are just production scaling issues
IMS 2004 Plenary
31
Conclusions
• If you’re interested in developing and
marketing civil radio technology,
awareness of spectrum policy is
increasingly important
• Need for technical community to get
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture. more involved in spectrum policy is
increasing!
– “Spectrum policy is too important to be left
to lawyers”
IMS 2004 Plenary
32
Have a great
conference!
QuickTime™ and a
TIFF (Un compressed) decompressor
are neede d to see this picture.
IMS 2004 Plenary
33
Required Advances in Microwave
Devices and Components to Meet the
Needs of Future Wireless
Telecommunication Systems
Michael Marcus
mjmarcus@alum.mit.edu
QuickTime™ an d a
TIFF (LZW) decompressor
are need ed to see this p icture .
Qui ckTi me™ and a
TIFF (Uncompressed) d ecompresso r
are ne ede d to see thi s pi cture.
Associate Chief for Technology Visiting Researcher
Office of Engineering and Technology École nationale supérieure
Federal Communications Commission des télécommunications
Until March 31, 2004 QuickTime™ and a After 5 April 2004
TIFF (Un compressed) decompressor
are neede d to see this picture.
IMS 2004 Plenary
34