Transcript Spectrum Management Fundamentals

Kyiv Workshop (CoE 6842)
Monitoring of Radio Frequency Spectrum
New Communications Technologies &
Implications on Spectrum Monitoring
Professor Anastasios D Papatsoris
Department of Informatics & Communications
Serres Institute of Education & Technology
[email protected], Tel: +30 23210 49157
http://www.teiser.gr/icd/staff/papatsoris/index_en.html
Talk structure

The aim of this talk is:
– To review in a synoptic way the latest
developments in modern digital
communications techniques,
– To present in a concise and illustrative way
some of the dominant communications
applications, and
– To discuss the implications on Spectrum
Monitoring from a technical and administrative
point of view.
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New communications
technologies

The advances in technology have enabled the
incorporation of complex digital communications
techniques (modulation, coding, access schemes)
in all radio communications applications in an
economical way.
 This led to the so called “digital explosion” and
most services and applications are today digital or
about to become.
 Especially relevant to Spectrum Monitoring is the
development of new modulation and access
techniques, in particular OFDM and CDMA,
respectively.
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COFDM

COFDM involves modulating the data onto
a large number of carriers using the FDM
technique. The key features which make it
work, in a manner that is so well suited to
terrestrial channels, include:
– orthogonality (the “O” of COFDM);
– the addition of a guard interval;
– the use of error coding (the “C” of COFDM),
interleaving and channel-state information
(CSI).
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COFDM – FDM


If coping with any appreciable level of delayed signals is required, the
symbol rate must be reduced sufficiently so that the total delay spread
(between the first and last received paths) is only a modest fraction of
the symbol period. The information that can be carried by a single
carrier is thus limited in the presence of multipath.
If one carrier cannot carry the information rate required, why not
divide the high-rate data into many low-rate parallel streams, each
conveyed by its own carrier – of which there are a large number. This
is a form of FDM.
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COFDM – Orthogonality

The use of a very large number of carriers implies that an
equally great number of modulators/demodulators and
filters, as well as an increase of bandwidth would be
required to accommodate them.
 Fortunately, this isn’t the case if we specify that the
carriers are evenly spaced by precisely fu=1/Tu, where Tu is
the period (the “useful” or “active” symbol period) over
which the receiver integrates the demodulated signal. This
is in fact the equivalent of orthogonality in mathematics.
 k (t )  e
jku t
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
0, k  j 
, and  k (t )  (t ) dt  

1, k  j 

*
j
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Preserving orthogonality



In practice, the carriers are modulated
by complex numbers which change
from symbol to symbol. If the
integration period spans two symbols,
not only will there be same-carrier ISI,
but in addition there will be intercarrier interference (ICI) as well. This
happens because the beat tones from
other carriers may no longer integrate
to zero if they change in phase and/or
amplitude during the period.
This can be avoided by adding a guard
interval, which ensures that all the
information integrated comes from the
same symbol and appears constant
during it.
The guard interval length is chosen to
match the level of multipath expected.
It must not form too large a fraction of
Tu , otherwise too much spectral
efficiency will be sacrificed.
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Use of IFFT and FFT



In OFDM modulators, demodulators and integrators are
realised through the exploitation of the properties of the
discrete Fourier and Inverse Fourier transforms.
In the transmitter, the modulated waveform is constructed
though the application of the IFFT, whereas in the receiver
the demodulation process is realised through the
application of FFT. Common versions of the FFT operate
on a group of time samples (corresponding to the samples
taken in the integration period) and deliver the same
number of frequency coefficients. These correspond to the
data demodulated from the many carriers.
Thus, the availability of cheap FFT ICs eliminated the
need for thousands of modulators and demodulators.
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Choice of basic modulation


At the receiver, the corresponding demodulated value (the
frequency coefficient from the receiver FFT) has been
multiplied by an arbitrary complex number (the response
of the channel at the carrier frequency). The constellation
is thus rotated and changed in size. How can we then
determine which constellation point was sent?
One simple way is to use differential demodulation, such
as the DQPSK used in DAB. Information is carried by the
change of phase from one symbol to the next. As long as
the channel changes slowly enough, its response does not
matter. Using such a differential (rather than a coherent)
demodulation process causes some loss in thermal noise
performance – but DAB is nevertheless a very rugged
system.
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Choice of basic modulation


When higher capacity is needed, coherent demodulation is preferred.
In this, the response of the channel for each carrier is somehow determined,
and the received constellation is appropriately equalized before determining
which constellation point was transmitted.
 To do this in DVB-T, some pilot information is transmitted (so-called scattered
pilots) so that, in some symbols on some carriers, known information is
transmitted from which a sub-sampled version of the frequency response is
measured. This is then interpolated, using a 1-D or 2-D filter, to fill in the
unknown gaps, and is used to equalize all the constellations which carry data.
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Error coding

Uncoded OFDM does not perform very well in a
frequency selective channel.
 Thus, a soft-decision Viterbi decoder is used in the
receiver. The Viterbi decoder adds logarithmic
likelihoods to accumulate the likelihood of each
possible sequence sent by the transmitter.
 The Viterbi’s soft decision thresholds are
dynamically affected by the channel-state
information (CSI), i.e., data conveyed by carriers
having a high SNR are a priori more reliable than
those conveyed by carriers having a low SNR.
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Interleaving

If the relative delay of the echo is rather shorter than we have
just considered, then the notches in the channel’s frequency
response will be broader, affecting many adjacent carriers.
 This means that the coded data we transmit should not simply be
assigned to the OFDM carriers in a sequential order, since at the
receiver this would cause the Viterbi soft-decision decoder to be
fed with clusters of unreliable bits.
 This is known to cause a serious loss of performance, which can
be avoided by interleaving the coded data before assigning them
to OFDM carriers at the modulator.
 Interleaving can be implemented both in the time or frequency
domain. For a slowly varying channel frequency interleaving is
appropriate, whereas in cases where the frequency response of
the channel varies appreciably with time (i.e., large Doppler
shifts), time interleaving is appropriate.
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CDMA

Traditionally Code Division Multiple Access (CDMA) systems
have been used almost exclusively by the military as a means of
operating covert radio communications in the presence of high
levels of interference.
 In recent years, the interference immunity of CDMA for multiuser communications, together with its very good spectral
efficiency characteristics, has been seen to offer distinct
advantages for public cellular-type communications.
 There are two very distinct types of CDMA system, classified as
direct sequence CDMA (DSSS) and frequency hopping CDMA
(FHSS). Both of these systems involve transmission bandwidths
that are many times that required by an individual user, with the
energy of each user's signal spread with time throughout this
wide channel. Consequently these techniques are often referred
to as spread spectrum systems.
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Frequency hopping CDMA



Frequency hopping involves taking the narrow bandpass
signals for individual users and constantly changing their
positions in frequency with time.
In a frequency selective fading environment, the benefit of
changing frequency like this is to ensure that any one user's
signal will not remain within a fade for any prolonged
period of time. Clearly for frequency hopping to be
effective, the users must hop over a bandwidth
significantly wider than notch caused by frequency
selective fading.
In order to ensure that individual users never (or rarely)
hop onto the same frequency slot at the same time, causing
mutual interference, the carrier frequencies are assigned
according to a predetermined sequence or code.
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Example of FHSS

The GSM System has also provision within the Standard to
change frequency on a frame-by-frame basis, making it a
modest rate (1 / 4.165ms = 240 hops/second) frequency
hopping CDMA system.
 The motivation for adding the extra complexity of hopping
to GSM is twofold.
– Firstly, the 200 kHz channel bandwidth of GSM is not sufficient to
ensure that it will always be significantly wider than the coherence
bandwidth of the multipath environment, and thus not corrupted by
narrowband fading.
– Secondly, if there is a strong interference source on any given
channel, the hopping process will ensure that frames are only
corrupted on an occasional basis.
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FHSS and SMon

The FHSS signal parameters of
interest include: full hop
bandwidth; underlying signal
modulation; minimum frequency
difference between hops;
instantaneous received power; hop
rate and hop phase; angle of arrival
(DF).
 When multiple FHSS signals are
present in the same band, advanced
digital signal processing (DSP)
algorithms are required that
identify and isolate the signals by
hop rate, hop duration, hop phase,
and angle of arrival since all of the
signals will appear to be co-channel
interference.
FIGURE 10. Waterfall Plot of FHSS Signal
600
400
200
0
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0
10
20
30
40
Frequency
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60
70
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Direct sequence CDMA



In DS-CDMA, the narrowband signals from individual users are
spread continuously and thinly over a wide bandwidth using a
spreading sequence.
By mixing the narrowband user data signal with a locally generated
well-defined wideband signal, the user energy is spread to occupy
roughly the same bandwidth as the wideband source. The wideband
spreading signal is generated using a pseudo-random sequence
generator clocked at a very high rate (termed the chipping rate).
De-spreading of the signal is necessary in the receiver in order to
recover the narrowband user data modulation and this is accomplished
by mixing the received signal with an identical, accurately timed
pseudo-random sequence. This correlation process has the effect of
reversing the spreading action in the transmitter. De-spreading will
only occur, however, if the correct sequence is used at both ends of the
link, and if the two sequences are time aligned.
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DS-CDMA schematic
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Multi-user performance



Multi-user operation is achieved in direct sequence CDMA by assigning each user a
different spreading code or a different time alignment of a common spreading code.
Only that portion of the wideband spectral energy that has been spread by the same code
as used in the receiver will be detected. Users are thus able to coexist in the same
bandwidth and time space on the channel.
Like frequency hopping, spread spectrum CDMA overcomes the problem of frequency
selective fading by ensuring that most of the spread signal energy falls outside the
fading 'notches'.
If there is some correlation between spreading codes, as is almost always the case, then
there will be a small contribution to any individual de-spread user signal from all the
other spread users on the channel. Ultimately this puts an upper limit on the number of
users that can co-locate on the same piece of spectrum before the unwanted de-spread
energy gives rise to unacceptable data errors.
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DSSS and SMon



The main parameters to measure for DSSS signals include: carrier
frequency; transmitted bandwidth; number of users in the band; chip
rate; modulation type; instantaneous received power; angle of arrival
(DF).
Since DSSS signals will appear to be wideband noise to conventional
receiving and direction-finding equipment, new equipment and
techniques are required in order to detect, process, and locate these
signals. The preferred technique is to use a phase coherent multichannel (two or more) wide-band acquisition digital signal processing
system.
In order to demodulate the DSSS signal, the receiver must possess the
same frequency, chip rate and spreading sequence as the transmitter,
and it must be able to synchronize correctly to this sequence.
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Radio communications
applications

Fixed wireless access
– LMDS, MMDS, MVDS



Satellite networks VSAT star and meshed configurations
High Altitude Platforms (HAPs)
Digital Radio
– DAB-T, DAB-S

Digital Interactive Television
– Terrestrial DVB-T/C, DVB-X (land mobile), Satellite DVB-S

Mobile communications
– UMTS
– TETRA

Fixed limited mobility
– Bluetooth
– HIPERLAN 1/2, HIPERACCESS, HIPERLINK
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Network & system
architecture

Communication networks could be
considered as divided into two parts: the
access network and the core network.
– The access network delivers the communication
service to the end user whereas,
– the core network (or backbone) transports high
volumes of traffic between routers.
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Fixed Wireless Access (FWA)

FWA: The provision of
two-way broadband
services through fixed
microwave links.
 According to the
frequency band of
operation and the offered
services the following
technologies can be
distinguished:
– LMDS (3.4 - 3.6 GHz, 24 28GHz, voice, data, ΙΡ),
– MVDS (40 GHz, video)
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FWA network architecture





An LMDS network consists primarily of four parts:
network operations centre, fibre or microwave based
infrastructure, base station and CPE.
Various network architectures are possible within LMDS,
MMDS, MVDS system design. The majority of system
operators use point-to-multipoint wireless access designs,
although point-to-point systems and TV distribution
systems can be provided within the LMDS system.
Both ATM and IP transport methodologies can be
implemented by system operators at national level.
Access protocols include both TDD and FDD schemes.
Modulation can be dynamic according to channel
conditions, and includes QPSK, 16-QAM and 64-QAM.
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Satellite network topologies
 Depending
on the type of payload,
basic reference architectures for
point-to-point broadband can be
considered:
– Distributed bent-pipe satellite Internet access
– Meshed regenerative satellite network for
professional users or for backbone
connectivity.
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Distributed bent-pipe
satellite access

Distributed broadband access via satellite provides
a high-capacity point-to-point on top of
multicasting for ubiquitous internet access. This
architecture has a multi-star topology with few
gateways that transmit one or more high data rate
forward link to a large number of small user
terminals. In the return direction, the remote user
terminals transmit in bursts at low to medium data
rates to the gateway.
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Meshed regenerative
satellite network

With on-board processing and switching
topologies, the satellite is the focal point of a star
network instead of a gateway earth station. The
satellite is connected to the terrestrial gateways by
high data rate links. On-board the satellite the onboard processor (OBP) demodulates and
demultiplexes the uplink transmissions from user
terminals and switches it into downlinks streams
intended for particular geographical areas.
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Star TDM/TDMA VSAT
configuration



The Hub transmits an
outbound channel (□)
divided into time slots
(TDM), which is received
by all VSATs, but can be
addressed to a group.
Each VSAT contends for
time slots on a shared
TDMA inbound channel
(□□□).
If they collide in a slot,
they re-transmit after a
random time delay.
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SCPC mesh/DAMA system



A VSAT uses a TDMA CSC
(command, signalling &
control) (□) channel to request
that the Master station sets up a
link between the requesting
VSAT and another.
The Master station then informs
the called VSAT on request and
allocates two channels (□□) to
serve as bi-directional link
between the two sites.
As soon as the call is finished,
the channels are returned to the
pool of available capacity.
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VSAT equipment



The VSAT consists of two
units – one outdoor and
one indoor.
The outdoor unit
comprises of an antenna of
small dimensions and a
microwave transceiver.
The indoor unit operates
as modem connecting the
satellite network to the
user equipment, i.e., PCs,
LANs, phone, fax, etc.
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Point-to-point

Point-to-point SCPC (single
channel per carrier) links are the
satellite equivalent of a
terrestrial leased line
connection. They are usually
set-up on a permanent, 24 hour
basis and are thus more costly
in satellite capacity and less
efficient if not used all the time.
However, they do support high
bandwidths (typically multiples
of 2 Mbps) and can easily be
used to carry data, voice and
even video traffic.
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High Altitude Platform
Stations



HAP located at 21 to 25 km.
Communication is between
HAP and UT on the ground in a
cellular arrangement.
Communication also between
HAP and a number of gateway
stations on the ground, which
provide interconnection with
the fixed net.
Coverage
Area
UAC
SAC
RAC
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Elevation
Ground range
angle (deg) (km)
90 – 30
0 – 40
30 – 15
40 – 90
15 – 5
90 – 220
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Operational characteristics

Powered by efficient solar cells and regenerative hydrogen-oxygen fuel
cells. Electrolysis converts water into fuel during the day and uses it to
generate the electrical power needed for night operation.
 HAPN has a star configuration, with the HAPS platform serving as the
main hub. The payload projects multiple spot beams onto the ground and
provides ubiquitous coverage over a 150 km diameter.
 UT are portable devices that communicate with the payload directly. A UT
consists of an antenna and a digital interface unit. User-to-user
communications are switched directly by the payload, which contains a
large ATM switch.
 Platform payload will have gimballed slotted array antennas with polarizer
to ensure proper cross-polarization isolation. The array antennas will
project a total of 700 beams in each of the UAC and SAC zones, and
selective coverage in the RAC zone.
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HAP Network Configuration
User devices
HAPS platform with
communications payload
Gateway stations
Gateway
station
WWW
PSDN
Nearby subscriber set
PSTN
PSDN: packet switched data network
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HAPN Services

The HAPS system is designed to provide variable rate, full
duplex, digital channels to homes and the so-called small
office/home office (SOHO).
 The intended services are multimedia applications such as
videoconferencing and videophones in addition to high-speed
Internet access. The high bit rates, a large metropolitan
coverage, and the fact that the user terminals are not
dependent upon a ground infrastructure, also makes the HAPS
an ideal platform for telecommuting and working-at-home,
your own home or your client's home. Therefore, the system
is designed to support a large number of virtual local area
networks (LANs), so users can access their corporate
networks as if they were in the office.
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Communication System

To maximize spectral efficiency, a dynamic assignment multiple
access (DAMA) scheme is used to allow users to share
bandwidth efficiently, and there are on-board asynchronous
transfer mode (ATM) switches and ATM multiplexers to
statistically multiplex the user traffic.
 UL and DL use QPSK and rate 0.6 concatenated FEC coding
(Reed-Solomon + rate 2/3 convolutional coding with constraint
length 9). Interleave coding is also used to mitigate burst errors.
Because of efficient sharing of bandwidth and the low-duty
factor of most types of broadband traffic, all 110,560 users can
expect to achieve a maximum upload speed of 2.048 Mbit/s and
download speed of 11.24 Mbit/s with a frequency allocation of
only 2x100 MHz.
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Communication System (cont)


Assuming an average of 10% of the total subscriber population to be
active at any given time, a single HAPS network can thus support a
subscriber population of about one million users given a 2x100
MHz allocation. If the frequency allocation is increased to 2x300
MHz, then a single HAPN can be expected to support more than
five million subscribers.
The baseline system also includes multiple gateway ground stations
which use high-speed synchronous TDM per link for feeder traffic
interconnecting HAPN to PSTN and the Internet. The feeder link
speed is up to 0.72 Gbit/s for a 300/300 MHz frequency allocation.
64-QAM modulation and rate 0.71 FEC coding are used to optimize
the available bandwidth. Additional high-speed point-to-point links
can also be provided for corporate customers and service providers.
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Communication System (cont)

Each uplink TDMA time slot carries one ATM cell. The
asynchronous nature of ATM provides great flexibility. For
example, no burst time plan is required. The aforementioned
DAMA scheme can be integrated with ATM call and traffic
management to maximize the efficiency of communication
resource management.
 On the user side, intelligent ATM multiplexers are used to reduce
the number of ports on the main switch. Each ATM Mux
multiplexes 16 beams into an OC3 (optical carrier, level 3
(155.52 Mbit/s)) port on the switch. At least 44 ports are needed
to handle >1 400 beams. The dynamic TDMA turns each beam
into a shared bus. Up to 1,000 user terminals can be registered at
any time. The design basically requires the ATM Mux to handle
the non-standard part of the signalling protocols, so we can use
standard ATM switches.
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End-to-end networking
FIGURE 2
End-to-end networking (2 x 100 MHz allocation, single zone)
2/10 Mbit/s
8  34 Mbit/s
155 Mbit/s
Multiplexer
- single terminal
- small LAN
- server and eLAN
16
Multiplexer
(1 000)
1
44
Onboard ATM switch
1
Gateway
switch
1
Carrier/ISP
backbone
15
Gateway
switch
Router
Another subscriber set
 11 Gbit/s full duplex, redundant
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1500-02
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Ground segment and control

The ground system consists of gateway stations and the HAPS control
centre. Each gateway station will use high-gain steerable antennas with
narrow beams. The RF equipment is similar to those on the payload.
The ATM switch required is not large - about four OC3 ports plus
whatever is necessary for local servers and/or network management.
 The HAPS control centre consists of one gateway station to provide
communication with the payload and the rest of the system, and four
operations and management entities:
– The hardware configuration control centre (tracking, telemetry and
command of both the platform and the payload).
– The communications resource control centre (real-time control of the
network resources, e.g. call control, radio resource management, etc.)
– The remote ground station control centre (essentially the NOC.)
– The regional business centre (financial control, billing, trend analysis.)
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HAPS Network
HAPS airship
HAPS airship
HAPS airship
20 km
367 spot beams
20 deg.
HAPS ground station
110 km
Footprint or cell in which the same frequency band is used
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DAB production architecture



In DAB each service signal is coded
individually at source level, error
protected and time interleaved in the
channel coder.
Then the services are multiplexed in the
Main Service Channel (MSC), according
to a pre-determined, but adjustable,
multiplex configuration. The multiplexer
output is combined with Multiplex Control
and Service information, which travel in
the Fast Information Channel (FIC), to
form the transmission frames in the
Transmission Multimplexer.
Finally, Orthogonal Frequency Division
Multiplexing (OFDM) is applied to shape
the DAB signal, which consists of a large
number of carriers each QPSK modulated.
The signal is then transposed to the
appropriate radio frequency band,
amplified and transmitted.
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DAB receiver architecture

The Figure demonstrates a
conceptual DAB receiver. The
DAB ensemble is selected in the
analogue tuner with the digitized
output of which is fed to the
OFDM demodulator and channel
decoder to eliminate transmission
errors.
 The information contained in the
FIC is passed to the user interface
for service selection and is used to
set up the receiver appropriately.
 The MSC data is further processed
in an audio decoder to produce the
left and right audio signals or in a
data decoder (Packet Demux) as
appropriate.
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DAB transmission signal

In order to allow the DAB system to be used in different transmission network
configurations and over a wide range of operating frequencies, four transmission
modes are defined:
–
–
–



Transmission mode I with 192 carriers and 96 ms frame duration
Transmission modes II with 384 and III with 768 carriers, respectively, both of 24 ms frame
duration
Transmission mode IV with 1536 carriers and 48 ms frame duration.
The DAB signal consists of consecutive Orthogonal Frequency Division Multiplex
(OFDM) symbols. The OFDM symbols are generated from the output of the
multiplexer which combines the Common Interleaved Frames (CIFs) and the
convolutionally encoded Fast Information Blocks (FIBs). Their generation involves
the processes of Differential Quadrature Phase Shift Keying (D-QPSK), frequency
interleaving, and D-QPSK symbols frequency multiplexing (OFDM generator).
The transmission frame consists of a sequence of three groups of OFDM symbols:
synchronization channel symbols, Fast Information Channel symbols and Main
Service Channel symbols. The synchronization channel symbols comprise the null
symbol and the phase reference symbol.
The null symbols are also used to allow a limited number of OFDM carriers to
convey the Transmitter Identification Information (TII).
1 – 4 June 2004, Kyiv
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Implications on Spectrum Monitoring © ADP
44
DAB radio frequencies

Transmission mode I is intended to be used for
terrestrial Single Frequency Networks (SFN) and
local-area broadcasting in Bands I, II and III.
 Transmission modes II and IV are intended to be
used for terrestrial local broadcasting in Bands I,
II, III, IV, V and in the 1,452 – 1,492 MHz
frequency band (i.e. L-Band). It can also be used
for satellite-only and hybrid satellite-terrestrial
broadcasting in L-Band.
 Transmission mode III is intended to be used for
terrestrial, satellite and hybrid satellite-terrestrial
broadcasting below 3,000 MHz.
1 – 4 June 2004, Kyiv
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45
Digital Video Broadcasting

DVB uses:
– Video compression - MPEG-2 and Audio compression - MPEG Layer II. That
means much more TV programmes can be fit into the same channel capacity as
analogue TV
– A satellite transponder using DVB can contain 6-8 times more TV programmes
than analogue TV


DVB is also completely digital, opening up the world of Electronic
Programme Guides, Internet, data broadcasting, advanced interactive TV, etc.
DVB transmission systems:

– use the concept of data containers or data pipelines which can carry all kinds of
data "quasi-error free" over all kinds of media (satellite, cable, (S)MATV, terrestrial
channels, MMDS).
– are transparent for SDTV, EDTV, HDTV, for audio at all quality levels and for all
kinds of general data.
– are part of a family of systems that make use of maximum commonality in order to
enable the design of "synergetic" hardware and software.
Various standards have been developed, i.e., DVB-T, DVB-C, DVB-S.
1 – 4 June 2004, Kyiv
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DVB Transmission

The core of DVB's systems is its series of transmission specifications. First
approved in 1994, the DVB-S satellite transmission standard, based on QPSK,
is now the de-facto world satellite transmission standard for digital TV
applications.
 The DVB-C, cable delivery mechanism, is closely related to DVB-S, and is
based around 64-QAM, although higher order modulation schemes are also
supported.
 DVB-T is the youngest of the three core DVB systems and the most
sophisticated. Based on COFDM (Coded Orthogonal Frequency Divisional
Multiplexing) and QPSK, 16 QAM and 64 QAM modulation, it is the most
sophisticated and flexible digital terrestrial transmission system available
today. DVB-T allows services providers to match, and even improve on,
analogue coverage, at a fraction of the power. It extends the scope of digital
terrestrial television in the mobile field, which was simply not possible before,
or with other digital systems.
 In DVB-T data to be transmitted are first coded with a Reed-Solomon code,
interleaved with an additional “outer” interleaver, then passed to the “inner”
convolutional coder. At the receiver, the Viterbi decoder is followed by an
“outer” interleaver and the “outer” hard decision R-S decoder.
1 – 4 June 2004, Kyiv
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DVB-T signal

DVB-T has two modes with either
1705 or 6817 carriers in a 7.61
MHz bandwidth, with a wide range
of guard intervals from 7 to 224 µs.
Coherent demodulation is used,
with QPSK / 16-QAM / 64-QAM
constellations. In conjunction with
options for inner-code rate, this
provides extensive trade-off
between ruggedness and capacity
(from 5 to 31.7 Mbit/s).
 The figures quoted above relate to
the use of nominally 8 MHz
channels. The DVB-T specification
can be adapted to 6 or 7 MHz
channels by simply scaling the
clock rate; the capacity and
bandwidth then follow in the same
proportion.
1 – 4 June 2004, Kyiv
0dB
*ATTEN
RL
-20.0dBm
10dB/
MKR 1
646.19 MHz
MKR 2
653.81 MHz
MKR DELTA
7.63 MHz
.16 dB
CENTER
650.00MHz
*RBW
3.0kHz
SPAN
VBW 3.0kHz
New Communications Technologies &
Implications on Spectrum Monitoring © ADP
10.00MHz
SWP
48
2.8sec
Digital Convergence


With the arrival of the era of Digital Convergence,
emerging new technologies are blurring the boundaries
between the traditionally separate communication
platforms of the computing, broadcasting, and
telecommunications industries. Mobile communication in
particular is increasingly becoming the driver for this
process.
DVB 2.0 is DVB’s consortium take on Digital
Convergence, and consists of a roadmap for the
development of digital broadcasting technology in the
converging world of today.
1 – 4 June 2004, Kyiv
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DVB-X, the mobile DTV

DVB is addressing the technology
developments with respect to
mobile communication. GPRS and
UMTS will be able to offer various
multimedia services. Ad Hoc
groups are assessing how GPRS
and UMTS can work with DVB
systems, and are looking at the
service convergence and network
cooperation between these
platforms.
 In addition to the 3G networks,
Wireless Local Area Networks are
gaining in importance and are taken
into account in DVB activities.
 DVB over IP and IP over DVB
specifications are being developed.
1 – 4 June 2004, Kyiv
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UMTS services


UMTS offers teleservices (like speech or SMS) and
bearer services, which provide the capability for
information transfer between access points. It is possible
to negotiate and renegotiate the characteristics of a bearer
service at session or connection establishment and during
ongoing session or connection. Both connection oriented
and connectionless services are offered for Point-to-Point
and Point-to-Multipoint communication.
Bearer services have different QoS parameters for
maximum transfer delay, delay variation and bit error
rate. Offered data rate targets are:
– 144 kbits/s satellite and rural outdoor
– 384 kbits/s urban outdoor
– 2048 kbits/s indoor and low range outdoor
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UMTS network services

UMTS network services have different QoS classes for four types of
traffic:
–
–
–
–


Conversational class (voice, video telephony, video gaming)
Streaming class (multimedia, video on demand, webcast)
Interactive class (web browsing, network gaming, database access)
Background class (email, SMS, downloading)
UMTS will also have a Virtual Home Environment (VHE). It is a
concept for personal service environment portability across network
boundaries and between terminals. Personal service environment
means that users are consistently presented with the same personalized
features, User Interface customization and services in whatever
network or terminal, wherever the user may be located.
UMTS also has improved network security and location based
services.
1 – 4 June 2004, Kyiv
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UMTS architecture



A UMTS network consist of three
interacting domains; Core Network
(CN), UMTS Terrestrial Radio Access
Network (UTRAN) and User
Equipment (UE).
The main function of the core network
is to provide switching, routing and
transit for user traffic. Core network
also contains the databases and network
management functions. The basic Core
Network architecture for UMTS is
based on GSM network with GPRS.
The UTRAN provides the air interface
access method for User Equipment.
Base Station is referred as Node-B and
control equipment for Node-B's is
called Radio Network Controller
(RNC).
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TETRA

TErrestrial Trunked RAdio (TETRA) is the
modern digital Private Mobile Radio (PMR)
and Public Access Mobile Radio (PAMR)
technology for police, ambulance and fire
services, security services, utilities, military,
public access, fleet management, transport
services, closed user groups, factory site
services, mining, etc.
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TETRA specification





TETRA offers fast call set-up time, addressing the critical needs of many user
segments, excellent group communication support, Direct mode operation
between radios, packet data and circuit data transfer services, frequency
economy and excellent security features.
TETRA uses Time Division Multiple Access (TDMA) technology with 4 user
channels on one radio carrier and 25 kHz spacing between carriers. This makes
it inherently efficient in the way that it uses the frequency spectrum.
The modulation scheme is π/4-shifted Differential Quaternary Phase Shift
Keying (π/4-DQPSK) with root-raised cosine modulation filter and a roll-off
factor of 0,35. The modulation rate is 36 kbit/s.
TETRA trunking facility provides a pooling of all radio channels which are
then allocated on demand to individual users, in both voice and data modes.
By the provision of national and multi-national networks, national and
international roaming can be supported, the user being in constant seamless
communications with his colleagues.
TETRA supports point-to-point, and point-to-multipoint communications both
by the use of the TETRA infrastructure and by the use of Direct Mode without
infrastructure.
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TETRA architecture
1b
3
1a
BS
BS
NMS
BS
BS
BS
BS
5
2
6
PSTN, ISDN
PDN
1 – 4 June 2004, Kyiv
4
.Another
TETRA
Network
Remote Line
Station
(Despatcher)
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56
TETRA V+D air interface
Air Interface
V
Uplink
D
TETRA
Infrastructure
TDMA
FRAME
V
TS 1
D
TS 2
D
TS 3
V
TS 4
V
V
D
1 – 4 June 2004, Kyiv
Downlink
TS = Time Slot
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Implications on Spectrum Monitoring © ADP
57
Air interface variants
DMO
AIR I/F
TMO
AIR I/F
PEI
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TETRA in 3G era
Network
Management
Service
Nodes
Customer
Care Billing
UMTS Core Network
Transit Layer
GSM
Access
Network
Management
Gateway
TETRA
Infrastructure
UMTS
Access
TAPS
Access
1 – 4 June 2004, Kyiv
TETRA1
Access
New Communications Technologies &
Implications on Spectrum Monitoring © ADP
TETRA1
+TEDS
Access
59
TETRA Spectrum


For emergency systems in Europe the frequency bands
380-383 MHz and 390-393 MHz have been allocated for
use by a single harmonized digital land mobile systems by
the ERC Decision (96)01. Additionally, whole or
appropriate parts of the bands 383-395 MHz and 393-395
MHz can be utilized should the bandwidth be required.
For civil systems in Europe the frequency bands 410-430
MHz, 870-876 MHz / 915-921 MHz, 450-470 MHz, 385390 MHz / 395-399,9 MHz, have been allocated for
TETRA by the ERC Decision (96)04.
1 – 4 June 2004, Kyiv
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Bluetooth

Bluetooth is a short-range radio link intended to replace the
cables connecting portable and/or fixed electronic devices.
Key features are robustness, low complexity, low power
and low cost.
 Bluetooth operates in the unlicensed ISM band at 2.4 GHz.
Although globally available, the exact location and the
width of the band may differ by country. In the US and
Europe (including UK), a band of 83.5 MHz is available;
in this band 79 RF channels spaced 1 MHz apart are
defined. A frequency hop transceiver is applied to combat
interference and fading.
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Modulation characteristics




A Gaussian shaped, binary FSK modulation is applied with a BTs product of 0.5 to
minimize transceiver complexity. A binary one is represented by a positive frequency
deviation, a binary zero by a negative frequency deviation. The maximum frequency
deviation should be between 140 kHz and 175 kHz and never less than 115 kHz. The
symbol rate is 1 Ms/s.
A slotted channel is applied with a nominal slot length of 625 μs. For full duplex
transmission, a Time-Division Duplex (TDD) scheme is used. On the channel,
information is exchanged through packets. Each packet is transmitted on a different hop
frequency. A packet nominally covers a single slot, but can be extended to cover up to
five slots.
The Bluetooth protocol uses a combination of circuit and packet switching. Slots can be
reserved for synchronous packets. Bluetooth can support asynchronous data channel, up
to three simultaneous synchronous voice channels, or a channel which simultaneously
supports asynchronous data and synchronous voice. Each voice channel supports 64 kb/s
synchronous (voice) channel in each direction. The asynchronous channel can support
maximal 723.2 kb/s asymmetric (and still up to 57.6 kb/s in the return direction), or
433.9 kb/s symmetric.
The Bluetooth system consists of a radio unit, a link control unit, and a support unit for
link management and host terminal interface functions.
1 – 4 June 2004, Kyiv
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Bluetooth transmitter

Each device is classified into 3 power classes, Power Class
1, 2 & 3.
– Power Class 1: is designed for long range (~100m) devices, with a
max output power of 20 dBm,
– Power Class 2: for ordinary range devices (~10m) devices, with a
max output power of 4 dBm,
– Power Class 3: for short range devices (~10cm) devices, with a
max output power of 0 dBm.

The Bluetooth radio interface is based on a nominal
antenna power of 0dBm. Each device can optionally vary
its transmitted power. Equipment with power control
capability optimizes the output power in a link with LMP
commands. It is done by measuring RSSI and report back
if the power should be increased or decreased.
1 – 4 June 2004, Kyiv
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Bluetooth receiver

Sensitivity Level: The receiver must have a sensitivity
level for which the bit error rate (BER) 0.1% is met. For
Bluetooth this means an actual sensitivity level of -70dBm
or better.
 Interference Performance: The interference performance
on Co-channel and adjacent 1 MHz and 2 MHz are
measured with the wanted signal 10 dB over the reference
sensitivity level. On all other frequencies the wanted signal
shall be 3 dB over the reference sensitivity level.
 Out-of-Band blocking: The out-of-band blocking is
measured with the wanted signal 3 dB over the reference
sensitivity level. The interfering signal shall be a
continuous wave signal. The BER shall be less than or
equal to 0.1%.
1 – 4 June 2004, Kyiv
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BRAN – HIPERLAN/1


HIPERLAN Type 1 is a Radio LAN standard designed to
provide high-speed communications (20 Mbit/s) between
portable devices in the 5 GHz range. It is intended to allow
flexible wireless data networks to be created, without the
need for an existing wired infrastructure. In addition it can
be used as an extension of a wired LAN. The support of
multimedia applications is possible.
HIPERLAN/1 devices may be operated in Europe in the
5.15 – 5.30 GHz frequency band according to CEPT
Recommendation T/R 22-06. Five HIPERLAN/1 channels
may be accommodated in the 5.15 – 5.30 GHz band.
Channels 0, 1, 2 are the mandatory default channels. The
availability of channels 3, 4 is subject to national
administrations.
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HIPERLAN/1


Physical Layer: Data is transmitted in bursts containing a
number of FSK-modulated low rate bits and a GMSK
(BT=0,3) high rate bit stream comprising a
synchronization/training sequence of 450 bits and data
blocks of 496 interleaved, BCH(31,26)-coded bits. Each
burst is built from a CAC PDU. The signalling rate for
high rate transmission is 23.5 Mbps (this results in net
data rates approximately up to 20 Mbit/s) and the low
signalling rate 1.47Mbps. Nominal carrier bandwidth is
23.5 MHz.
Specification: The HIPERLAN/1 Functional
Specification is contained in EN 300 652. Type approval
requirements and protocol conformance testing
specifications are covered in the ETS 300 836 series.
1 – 4 June 2004, Kyiv
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BRAN – HIPERLAN/2


HIPERLAN/2 is a flexible Radio LAN standard designed to provide
high speed access (up to 54 Mbit/s at PHY layer) to a variety of
networks including 3G mobile core networks, ATM networks and IP
based networks, and also for private use as a wireless LAN system.
Basic applications include data, voice and video, with specific QoS
parameters taken into account. HIPERLAN/2 systems can be deployed
in offices, classrooms, homes, factories, hot spot areas like exhibition
halls and more generally where radio transmission is an efficient
alternative or a complement to wired technology.
HIPERLAN/2 marks a significant milestone in the development of a
combined technology for broadband cellular short-range
communications and wireless Local Area Networks (LANs) which will
provide performance comparable with that of wired LANs. Since the 5
GHz band to be exploited by the HIPERLAN/2 standard is allocated to
wireless LANs world-wide, HIPERLAN/2 has the potential to enable
the success of wireless LANs on a global basis.
1 – 4 June 2004, Kyiv
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HIPERLAN/2



Modes of operation: HIPERLAN/2 relies on cellular networking
topology combined with an ad-hoc networking capability. It supports
two basic modes of operation: centralized mode and direct mode.
The centralized mode is used in the cellular networking topology
where each radio cell is controlled by an access point covering a
certain geographical area. In this mode, a mobile terminal
communicates with other mobile terminals or with the core network
via an access point. This mode of operation is mainly used in business
applications, both indoors and outdoors, where an area much larger
than a radio cell has to be covered.
The direct mode is used in the ad-hoc networking topology, mainly in
typical private home environments, where a radio cell covers the whole
serving area. In this mode, mobile terminals in a single-cell home
"network" can directly exchange data.
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HIPERLAN/2

Physical layer: The signal modulation is based on the Orthogonal Frequency
Division Multiplexing (OFDM) with several sub-carrier modulation and
forward error correction combinations that allow to cope with various channel
configurations. The main parameters have the following values:
– FFT size: 64.
– Number of used sub-carriers: 52, where 48 sub-carriers are used for data and the
rest for pilots.
– Channel Spacing: 20 MHz.
– Sampling rate: 20 Msamples/s.
– Guard interval: 800 ns default mode corresponding to 16 time samples; 400 ns as
an option.
– Sub-carrier modulation: BPSK, QPSK, 16QAM and optionally 64QAM.
– Sub-carrier demodulation: Coherent.
– Mandatory Forward Error Correction: a rate 1/2, constraint length 7 mother
convolutional code (9/16 and 3/4 by code puncturing).
– Supported data rates: 6, 9, 12, 18, 27, 36, 54 Mbit/s.
– Interleaving: Block interleaving with the size of one OFDM symbol.
1 – 4 June 2004, Kyiv
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HIPERLAN/2 Radio &
Spectrum

HIPERLAN/2 can support multi beam antennas (sectors) to improve the link
budget and to reduce interference in the radio network. It also defines a set of
protocols (measurements and signalling) to provide support for a number of
radio network functions, e.g. Dynamic Frequency Selection (DFS), link
adaptation, handover, multi beam antennas and power control, where the
algorithms are vendor specific.
 To cope with the varying radio link quality (interference and propagation
conditions), a link adaptation scheme is used. Based on link quality
measurements, the physical layer data rate is adapted to the current link
quality. Transmitter power control is supported in both mobile terminal
(uplink) and access point (downlink).
 The 5 GHz band is open in Europe, the United States and Japan. The current
spectrum allocation at 5 GHz comprises 455 MHz in Europe, 300 MHz in the
US, and 100 MHz in Japan.
 The PHY layer of IEEE 802.11 standard in the 5 GHz band is harmonized with
that of HIPERLAN/2.
1 – 4 June 2004, Kyiv
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BRAN – HIPERACCESS



HIPERACCESS is a standard for broadband multimedia
fixed wireless access. The HIPERACCESS specifications
will allow for a flexible and competitive alternative to
wired access networks. When finalized, HIPERACCESS
will be an interoperable standard, in order to promote a
mass market and thereby low cost products.
HIPERACCESS is targeting high frequency bands,
especially it will be optimized for the 40,5 - 43,5 GHz
band.
ETSI’s BRAN is co-operating closely with IEEE-SA
(Working Group 802.16) to harmonize the interoperability
standards for broadband multimedia fixed wireless access
networks.
1 – 4 June 2004, Kyiv
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BRAN – HIPERMAN

HIPERMAN will be an interoperable broadband fixed wireless access system
operating at radio frequencies between 2 GHz and 11 GHz. The HIPERMAN
standard is designed for Fixed Wireless Access provisioning to SMEs and
residences using the basic MAC (DLC and CLs) of the IEEE 802.16-2001
standard. It has been developed in very close cooperation with IEEE 802.16,
such that the HIPERMAN standard and a subset of the IEEE 802.16a-2003
standard will interoperate seamlessly.
 HIPERMAN is capable of supporting ATM, though the main focus is on IP
traffic. It offers various service categories, full Quality of Service, fast
connection control management, strong security, fast adaptation of coding,
modulation and transmit power to propagation conditions and is capable of
non-line-of-sight operation.
 HIPERMAN enables both PMP and Mesh network configurations.
HIPERMAN also supports both FDD and TDD frequency allocations and HFDD terminals. All this is achieved with a minimum number of options to
simplify implementation and interoperability.
1 – 4 June 2004, Kyiv
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BRAN – Standards summary
HIPERACCESS – This long range variant is intended for point-to-multipoint,
high speed access (25 Mbit/s typical data rate) by residential and small
business users to a wide variety of networks including the UMTS™ core
networks, ATM networks and IP based networks (HIPERLAN/2 might be used
for distribution within premises). Spectrum allocation in the 40,5 - 43,5 GHz
band are being discussed in the relevant CEPT working groups.
 HIPERMAN – This will be an interoperable broadband fixed wireless access
system operating at radio frequencies between 2 GHz and 11 GHz. The air
interface will be optimized for PMP configurations, but may allow for flexible
mesh deployments. The HIPERMAN standards specify the PHY and DLC
layers, which are core network independent, and the core network specific
Convergence sublayers.
 HIPERLINK – This variant will provide short-range very high-speed
interconnection of HIPERLANs and HIPERACCESS, e.g. up to 155 Mbit/s
over distances up to 150 m. Spectrum for HIPERLINK is available in the 17
GHz range. The work on HIPERLINK standardization has not started yet.

1 – 4 June 2004, Kyiv
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Regulatory implications

With the introduction of numerous new radio
applications, including short range devices and
technologies, interference and emission issues
become significant.
 In order to ensure the harmonious co-existence of
established and new services and technologies,
international organizations such as the IEC and
ITU, and regulatory bodies such as the RA of the
UK commissioned theoretical studies and practical
measurement campaigns.
1 – 4 June 2004, Kyiv
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CISPR – Aims

To promote international agreement on the aspects of radio
interference set out hereafter, thereby facilitating
international trade.
– 1) Protection of radio reception from interference sources such as:
•
•
•
•
electrical appliances of all types;
ignition systems;
electricity supply systems, including electric transport systems;
industrial, scientific and electromedical radiofrequency (excluding
radiation from transmitters intended for conveying information);
• sound and television broadcasting receivers;
• information technology equipment.
– 2) Equipment and methods for the measurement of interference.
– 3) Limits for interference caused by the sources listed in item 1).
1 – 4 June 2004, Kyiv
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CISPR – Aims (cont)

To promote international agreement on the aspects of radio
interference set out hereafter, thereby facilitating
international trade.
– 4) Requirements for the immunity of sound and television
broadcast receiving installations from interference and the
prescriptions of methods of measurement of such immunity.
– 5) Where possible overlap arises in the standards adopted by the
CISPR and other IEC and ISO Technical Committees, the
consideration jointly with those Committees of the emission and
immunity requirements for devices other than receivers.
– 6) Impact of safety regulations on interference suppression of
electrical equipment.
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Interference from new wireline
communications applications

Interference may be generated by new
communications applications offered over existing
wired infrastructure, such as xDSL, PLT/PLC.
 For the harmonious co-existence of existing, new
and future microwave communications
applications, emission limits in the frequency
range 1 GHz - 18 GHz need to be established.
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Interference from UTTNs



D Welsh, I D Flintoft and A D Papatsoris, ‘Cumulative Effect Of Radiated
Emissions From Metallic Data Distribution Systems On Radio Based Services’, Final
report for Radio Communications Agency contract AY3525, Document No R/00/026,
Project No 1191, University of York, May 2000,
(http://www.ofcom.org.uk/static/archive/ra/topics/research/topics/emc/ay3525/intro.h
tm).
I D Flintoft, D Welsh, and A D Papatsoris, ‘Accumulated Emissions From Metallic
Data Delivery Systems To Verify The Angle Of Radiation Of ADSL Systems And
Their Potential Effect On Aeronautical Services’, final report for
Radiocommunications Agency contract AY3525, University of York, July 2000,
(http://www.ofcom.org.uk/static/archive/ra/topics/research/topics/emc/ay3525/report
2.doc).
M H Capstick, I D Flintoft, and A D Papatsoris, ‘Specification of the Scope of Work
Needed to Determine the Technical and Operational Impact of Emissions from
Unstructured Telecommunication Transmission Networks Interfering with
Aeronautical and Maritime Radio Services in the UK’, final report for Radiocommunications Agency contract AY4075, 3rd Issue, University of York, May 2002,
(http://www.ofcom.org.uk/static/archive/ra/topics/research/topics/emc/ay4075final.p
df).
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UTTN emissions
5.5
20
10
5
15
15
25
20
3.5
20
20
15
10
15
25
25
2.5
20
2
20
1.5
20
15
25
20
25
25
10
0
0.5
1
10
0
1.5
2
15
10
5
London
0
15
0.5
20
Berlin
15
20
1


25
electric field strength, [dBuV/m]
10
25
20
3
2.4 MHz
4.8 MHz
8.4 MHz
20
15
vertical distance, [km]
4
10
15
4.5
25
25
5
30
20
2.5
3
3.5
horizontal distance, [km]
20
4
-5
4.5
5
5.5
0
100
200
300
400
500 600
distance, [km]
700
800
900
1000
Left. Cumulative downstream ADSL electric field contour plot at 1 km above ground.
Right. Cumulative sky wave PLT emission electric field reaching London from Berlin.
1 – 4 June 2004, Kyiv
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79
Emission limits for 1 – 18
GHz


CISPR aims: 3) Limits for
interference caused by the
sources listed in item 1).
A J Rowell, D W Welsh, and
A D Papatsoris, ‘Practical
Limits for EMC Emission
Testing at Frequencies Above
1 GHz’, final report for
Radiocommunications
Agency contract AY1255,
University of York, November
2000,
(http://www.ofcom.org.uk/stat
ic/archive/ra/topics/research/t
opics/emc/ay3601/ay3601.pdf
).
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SMon & Signal Analysis

Signal analysis is the process of extracting every possible
bit of transmitted information from a radio signal. The
information to be extracted can be the intentionally
transmitted information or information of technical nature.
 Communication is organised in different layers of the OSI
model. Therefore signal analysis can also be organised in
different layers like detection, spectrum analysis,
modulation recognition, analogue and digital
demodulation, code recognition and channel decoding.
Correlation analysis and cryptography are to some extent
part of the subject.
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81
Signal analysis system (SAS)


Since the monitoring services of the different
administrations have different needs, a signal analysis
system should be open and flexible in both physical
construction and functionality.
A DSP based system with upgradeable and re-configurable
hardware and software is the best choice.
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82
SAS specification




A SAS consists of a wide band and a narrow band analyser, which can
be implemented as separate systems or integrated in one system.
Wide band receiving increases the detection probability of short time
signals or burst signals (such as GSM traffic) in a wide frequency
range. It makes the analysis of communications relations (e.g. duplex
on different frequencies) possible. Wide band receiving is needed for
example for wide band CDMA signals, frequency hopping
communications or chirp signals.
Narrow band receiving has a better performance in dense scenarios
(for example the HF frequency range). Although narrowband
performance can be obtained by applying filtering techniques on the
signals sampled from the wide band analyser you have to make sure
that in this case the wideband analyser is not overloaded by strong
signals.
Dependent of the needs of the monitoring service only one or both
analysers can be implemented.
1 – 4 June 2004, Kyiv
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SMon of satellite emissions
The broadband analyzer performs:
–
–
–
LNA / LNB
LNA / LNB
RF matrix
1 - 18 GHz (40 GHz)
Positionneur
Positioner
1 - 3 GHz
SHF Receiver
IF 70 or 140 MHz
Splitter
Set of standard
demodulators and
decoders
V/UHF receiver
Wide band
analyser
40 MHz
Narrow-band
analyser
signal analysis:
–
–
–
–
–
–
–
–
band segmentation;
level measurement;
bandwidth measurement;
modulation rate measurement;
modulation characterization;
channel/noise ratio measurement;
channel/interference ratio measurement;
and
interference analysis (modulation
rhythm and carrier frequency
measurements).
Console
DVB
demodulators
Sensors
Control
stations
Ethernet 100 mbits/s

broadband signals acquisition up to 40
MHz on the 70 MHz IF at the output of
the receiver and its digitization;
display of the broadband spectrum in
the instantaneous bandwidth of the SHF
receiver (40, 20, 15, 10, or 5 MHz);
polarization determination through the
control of the feeders;
LNA / LNB
LNA / LNB
Switch matrix

Off-line analysis station
Firewall
RS232 concentrator
Sensor
remote control
Sat software
station
1 – 4 June 2004, Kyiv
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SMon of Fixed Links



Analogue links are typically frequency modulated with a base-band signal of several or many
multiplexed traffic channels. For multi-channel audio communications, the base-band structure
follows established group, master-group, and super-group conventions as defined by the ITU
Telecommunications Standardization Sector (ITU-T).
Digital links display only a band of spectral occupancy visually similar to filtered white noise. It is
not immediately evident from RF spectra whether any of the separate base-band channels are
occupied or not. It is necessary to discuss the construction of these signals before any analysis is
considered.
The source will typically be a single multiplexed digital signal as described by ITU-T
Recommendation G703. Similarly, digital modulation methods are equally varied, but may be
consistent in any one band, depending on national spectrum management policy.
1 – 4 June 2004, Kyiv
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SMon of fixed links


Monitoring of these transmissions has
to be from mobile units, because of the
reduced and narrowed geographical
area covered by the transmitted signal
at levels that can be received.
Normally, to measure such a system,
the monitoring antenna has to be in the
beam from the microwave transmitting
antenna, or otherwise closely coupled to
the transmitter or feed line.
In general, basic parameters to be
measured are :
–
–
–
–
–
–
–

Analyzing
equipment
Filter
Spectrum
Analyzer
LNA
Calibration input
carrier frequency,
field strength or power flux density,
occupied bandwidth,
deviation from assigned frequency,
observed polarisation,
class of emission
identification of signal source.
Two common methods are used:
–
–
Antenna
system
Antenna
system
Analyzing
equipment
RF mixer
Spectrum analyzer
Signal Analyzer
Receiver
LNA
IF port
Calibration input
Direct intercept
Intercept with mixer
1 – 4 June 2004, Kyiv
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SMon of Mobile
Communications

The minimum capabilities required to monitor a digital cellular telephone or
PCS system for regulatory compliance is an antenna and either an RF
spectrum analyzer or digital receiver with bandwidth sufficient for the type of
system in use, and analysis capability in both the time and frequency domains.
 A somewhat more sophisticated monitoring station will have the additional
capability to measure received signal strength, determine occupied bandwidth,
and have directional antennas to minimize interference. In addition, a
capability to perform direction-finding on the source of emissions is highly
desirable.
 A sophisticated station equipped to monitor digital cellular and PCS systems
must have wideband digital signal acquisition and analysis capability in time,
frequency, and phase domains. Of particular value is the capability to decode
and display the constellations of the complex digital modulation schemes to
aid in positive identification (vector signal analysis). A fully equipped station
will have equipment capable of detecting, demodulating, direction-finding
(locating), and analyzing wide bandwidth direct sequence and frequencyhopping spread spectrum signals.
1 – 4 June 2004, Kyiv
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Multimedia SMon

Multimedia monitoring could be included in an
administration’s typical radio and television
technical monitoring activities.
 This could include reception, decoding,
processing, recording and eventual analysis of
broadcast, fixed and mobile service transmissions
carrying multimedia.
 The same monitoring principles apply directly to
broadcasting conducted by wireless cable
television, satellite systems, and any other means
of wireless Internet distribution.
1 – 4 June 2004, Kyiv
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SMon of Multimedia


A multimedia monitoring system would need to be based on the up-todate technologies of multimedia video and radio broadcast processes,
including of MPEG coding/decoding , TCP/IP and HTML/Web.
A multimedia monitoring system should have the ability to
characterize a multimedia network by observing, for example, the
following system characteristics:
–
–
–
–
–
–

client-server distribution architecture;
web servers (Internet and Intranet transaction server);
TCP/IP network;
multicast (point to multipoint);
unicast (point to point); and
streaming.
By means of appropriate hardware and software, the multimedia
monitoring system would need the ability to intercept and record
information automatically, and at the appropriate time, restore the
information for analysis.
1 – 4 June 2004, Kyiv
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Conclusions




New communications technologies and applications
require advanced vector signal analysis techniques to be
decoded.
This dictates the need for sophisticated hardware and
highly specialised and expensive software.
It also requires the development of new skills to spectrum
monitoring personnel and suggests that Administrations
should adopt a continuous learning approach for their staff.
In a rapidly changing spectrum management field,
Administrations might wish to consider a new framework
of national strategy, in which the focus has shifted from
discovering and eliminating interference to measuring
sustainable – tolerable interference.
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