UNIVERSITY OF NAIROBI
DEPARTMENT OF ELECTRICAL AND INFORMATION ENGINEERING
CASE STUDY ON RADIO FREQUENCY SPECTRUM MANAGEMENT IN KENYA
PROJECT NO: PRJ69
BY
CHESANG K. ANTHONY
REG NO: F17/1796/2006
SUPERVISOR: Dr. CYRUS WEKESA
EXAMINER: Dr. V.K ODUOL
THIS PROJECT REPORT IS SUBMITED IN PARTIAL FULFILMENT OF THE
REQUIREMENT FOR THE AWARD OF A BACHELOR OF SCIENCE DEGREE IN
ELECTRICAL AND ELECTRONIC ENGINEERING.
18TH MAY 2011
DEDICATION
To my family
i
ACKNOWLEDGEMENT
My heartfelt gratitude first goes to Dr. Cyrus Wekesa Snr. Lecturer University of Nairobi, who
supervised this project; I am impressed by his guidance and simplicity of suggestions, which
really contributed to the success of this project work. I would like to thank my lecturers in the
Department of Electrical and Information Engineering for the enriched knowledge they imparted
on me for the past five years. More thanks to Eng. L.K Boruet, Mr. Kibe and Eng. Kandagor of
CCK, for the helpful information they provided me with regards to my project.
Thanks to all my classmates for their support during the development of this project.
ii
DECLARATION
Except where indicated and acknowledged, I certify that the information presented in this report
is my original effort and has not been presented before for a degree award in this or any other
university to the best of my knowledge.
………………………………………..
CHESANG K. ANTHONY
F17/1796/2006
This report has been submitted to the Dept. of Electrical and Information Engineering,
University of Nairobi with my approval as a supervisor:
………………………………
Dr. CIRUS WEKESA
Date: 18th May, 2011
iii
TABLE OF CONTENTS
Page
ACKNOWLEDGEMENT ....................................................................................................................... ii
1
2
CHAPTER 1: INTRODUCTION ........................................................................................................... 1
1.1
Problem Definition ................................................................................................................... 1
1.2
Objectives ................................................................................................................................ 1
1.3
Report Organization ................................................................................................................. 1
CHAPTER 2: LITERATURE REVIEW ..................................................................................................... 2
2.1
Radio frequency spectrum. ...................................................................................................... 2
2.2
Electromagnetic wave propagation .......................................................................................... 2
2.2.1
Line-of sight propagation .................................................................................................. 3
2.2.2
Ground wave propagation ................................................................................................ 3
2.2.3
Sky wave propagation....................................................................................................... 4
2.3
3
Nomenclature of RF bands ....................................................................................................... 5
CHAPTER 3: SPECTRUM MANAGEMENT IN GENERAL ....................................................................... 6
3.1
Introduction ............................................................................................................................. 6
3.2
Objectives of Spectrum Management ...................................................................................... 6
3.3
Radio Spectrum users............................................................................................................... 6
3.4
International Telecommunication Union (ITU). ......................................................................... 7
3.4.1
ITU Radio Regulations....................................................................................................... 7
3.4.2
ITU –R Recommendations................................................................................................. 8
3.4.3
World Radio Conferences (WRCs) ..................................................................................... 8
3.4.4
Regional Regulatory Conferences (RRCs) .......................................................................... 8
3.4.5
ITU Regions ...................................................................................................................... 9
3.5
Spectrum planning ................................................................................................................. 10
3.6
Spectrum engineering analysis and standards ........................................................................ 10
3.6.1
Prediction of radio wave propagation ............................................................................. 10
3.6.2
Protection ratio .............................................................................................................. 11
3.6.3
Transmitter equipment specification .............................................................................. 11
3.6.4
Interference analysis ...................................................................................................... 12
3.6.5
Necessary radio frequency bandwidth ............................................................................ 12
iv
3.6.6
4
Receiver equipment parameters..................................................................................... 13
CHAPTER 4: SPECTRUM MANAGEMENT IN KENYA............................................................ 14
4.1
Introduction ........................................................................................................................... 14
4.2
National Table of Frequency Allocation ................................................................................. 14
4.3
Mechanisms for dividing up access to spectrum. .................................................................... 15
4.4
SPECTRUM PRICING ............................................................................................................... 15
4.4.1
Spectrum pricing requirements. ..................................................................................... 16
4.4.2
Annual Current frequency spectrum fee schedule in Kenya ............................................ 17
4.5
SPECTRUM AUTHORIZATION .................................................................................................. 23
4.5.1
Parameters notified to ITU-R after assigning spectrum to a user ..................................... 23
4.5.2
Administrative Methods of assigning spectrum .............................................................. 24
4.5.3
Market Methods ............................................................................................................ 25
4.5.4
Current spectrum utilization in Kenya [source CCK database] ......................................... 26
4.5.5
Unlicensed Spectrum ...................................................................................................... 29
4.6
Spectrum monitoring and inspection...................................................................................... 30
4.6.1
Spectrum Monitoring Technology ................................................................................... 30
4.6.2
Monitoring Equipment ................................................................................................... 31
4.6.3
Designing Spectrum Monitoring Systems ........................................................................ 33
4.6.4
Spectrum monitoring capabilities in Kenya. .................................................................... 34
4.6.5
Radio spectrum management and monitoring system layout in Kenya ........................... 34
5
CHAPTER FIVE: IMPACT OF INTRODUCTION OF DIGITAL BROADCSTING ON SPECTUM UTILIZATION
IN KENYA. .............................................................................................................................................. 35
5.1
Introduction ........................................................................................................................... 35
5.1.1
Current Broadcasting Situation ....................................................................................... 36
5.1.2
Analog FM broadcasting analysis ................................................................................... 36
5.1.3
Analogue television broadcasting analysis ...................................................................... 36
5.2
Digital Terrestrial Television ................................................................................................... 37
5.2.1 DVB-T2 analysis .................................................................................................................. 38
5.2.3 Benefits of Digital Broadcasting. ............................................................................................ 41
5.2.4 Digital Signal distribution ...................................................................................................... 41
6
CHAPTER 6: CONCLUSIONS RECOMMENDATIONS .......................................................................... 43
6.1
Conclusions and Recommendations ...................................................................................... 43
v
7
APPENDIX ...................................................................................................................................... 45
vi
List of tables
Table 1.1 nomenclatures of RF bands ...................................................................................................... 5
Table 2.4 ............................................................................................................................................... 17
15. Table 3.4 Broadcast stations fee per transmitter ................................................................................ 19
Table 4.5 of bands for broadcasting Services and the planned digital service. ......................................... 35
Table 5.5 Comparison of parameters between DVB-T and DVB-T2 ...................................................... 38
Table 6.5 Number of television programmes per multiplex (8 MHz channel) for fixed reception with
DVB-T, 16-QAM,code rate2/3,FFT 8K,Guard interval 1/4 and DVB-T2 with16-QAM,code rate 5/6, FFT
16K,Guard interval 1/8 [6].................................................................................................................... 38
List of figures
page
Figure 1.1 electromagnetic wave ............................................................................................................. 2
Figure 2.1 Huygens’ Principle for (a) a plane wave and (b) a spherical wave............................................ 3
Figure 3.1 Line-of sight propagation ........................................................................................................ 3
Figure 4.1. Ground wave propagation ...................................................................................................... 3
Figure 5.1 Sky wave propagation ............................................................................................................. 4
Figure 6.3 ITU Regions ........................................................................................................................... 9
Figure 7.4 monitoring antenna with vertical dipole Direction finding antennas ....................................... 31
Figure 8.4mobile monitoring station ...................................................................................................... 31
Figure 9.4Image of triangulation location of a transmitter ...................................................................... 33
vii
LIST OF ABBREVIATIONS
CCK
Communications Commission of Kenya
ICT
Information Communication Technology
ITU
International Telecommunication Union
RF
Radio Frequency
ELF
Extremely Low Frequency
SLF
Super Low Frequency
ULF
Ultra Low Frequency
VLF
Very Low Frequency
LF
Low Frequency
MF
Medium Frequency
HF
High Frequency
VHF
Very High Frequency
UHF
Ultra High Frequency
SHF
Super High Frequency
EHF
extremely high frequency
dB
decibel
dBµV/M
decibel micro-volts per meter
BW
Bandwidth
TRXs
Transmitters
MHz
Megahertz
GHz
Gigahertz
KHz
Kilohertz
Hz
Hertz
KShs.
Kenya shillings
viii
ISM
Industrial Scientific Medical
RRC
Radio Regulations Conference
T-DAB
Terrestrial Digital Audio Broadcasting
DVB-T
Terrestrial Digital Video Broadcasting
HD-720P
High-definition progressively-scanned TV format of 1280 x 720 pixels
HD-1080i
High-definition interlaced TV format of 1920 x 1080 pixels
MPEG
Moving Picture Expert Group
AVC
Advanced Video Coding
OFDM
Orthogonal Frequency Division Multiplexing
SFN
Single Frequency Network
MFN
Multi-Frequency Network
WRC
World Radiocommunication Conference
ix
ABSTRACT
Radio frequency spectrum is a natural resource that can be used to increase the efficiency and
productivity of a nation. It is used to provide a wide variety of radio-communication services including
personal and corporate communications, radio navigation, aeronautical and maritime radio, broadcasting,
public safety and distress operations, radio location and amateur radio.
Frequency spectrum management tasks call for planning and coordination of frequency spectrum usage
at international and national levels; allocating and assigning spectrum nationally, monitoring, inspection
and resolving radio frequency interference.
In this project, various spectrum management activities carried out in Kenya to achieve efficient and
effective spectrum utilization are described. These activities cover the spectrum planning, pricing,
authorization, monitoring and inspection. The impact of introduction of digital broadcasting in Kenya on
spectrum utilization is also analyzed.
x
1
1.1
CHAPTER 1: INTRODUCTION
Problem Definition
Frequency spectrum management is an ever increasing challenge due to ever increasing number
of users of the existing radio services and the number of new radio based services. Radio
frequency spectrum is a limited natural resource. Anytime or anyplace a portion of it is used
precludes the use of that portion at that time or place. Without spectrum management, the
development of the ICT will be hindered resulting into economic impact to the country. Only
well organized spectrum management maximizes the benefits of its use. Spectrum must be
managed centrally to ensure consistent and logical approach to all frequencies.
Radio frequency unlike other resources;
·
Cannot be polluted, can only be subjected to harmful interference of which can be
purified for reuse once the source of this interference is eliminated
·
1.2
Cannot be depleted through use
Objectives
·
Read and understand spectrum management in general
·
To carry out a case study on frequency spectrum management in Kenya
·
Study the impact of introduction of digital broadcasting in Kenya on spectrum utilization
1.3
Report Organization
Chapter 2 covers a review on literature about radio frequency spectrum. The author then goes on
to develop a theoretical framework on spectrum management in general. Chapter 4 covers
spectrum management in Kenya. Chapter 5 analyses the impact of introduction of digital
broadcasting in Kenya on frequency utilization, then finally a conclusion and recommendations
documented.
1
2
CHAPTER 2: LITERATURE REVIEW
2.1 Radio frequency spectrum.
Radio frequency spectrum is a subset of the electromagnetic waves that is between 3 KHz to 300
GHz that is used for wireless communications.
Electromagnetic wave comprises electric and magnetic fields propagated by oscillating at
perpendicular planes to each other at a velocity of 3×108 m/s in vacuum. As shown in fig 1.1
Figure 1.1 electromagnetic wave
The velocity of propagation is given by expression c=f λ where c=3×108 m/s, f is the frequency in
Hz and λ is the wavelength in meters. According to the propagation characteristic, spectrum
using higher frequencies reaches shorter distances but has a larger carrying capacity while
spectrum using lower frequencies reaches longer distances but has a lower carrying capacity.
This characteristic limits the application of spectrum in various services. [1]
2.2 Electromagnetic wave propagation
Electromagnetic waves propagate as a series of expanding wave fronts. This can be best
understood by applying Huygens’ Principle of wave theory. This principle states that “each
element of the expanding wave fronts act as a source of radiation sending out a secondary
radiation from all elements of the original wave add up to form a new wave front ,each element
of which re-radiates in turn”. This illustrated in the figure 1.2 [1]
2
Figure 2.1 Huygens’ Principle for (a) a plane wave and (b) a spherical wave.
2.2.1 Line-of sight propagation
·
Transmitting and receiving antennae are in sight of each other
Figure 3.1 Line-of sight propagation
2.2.2 Ground wave propagation
·
Signals follow curvature of the earth.
·
Can propagate considerable distances.
·
Frequencies up to 2 MHz
Figure 4.1. Ground wave propagation
3
2.2.3 Sky wave propagation
·
Signal reflected from ionized layer of atmosphere back to earth.
·
Signal can travel a number of hops, back and forth between ionosphere and earth’s.
surface
·
Cover large distances.
Figure 5.1 Sky wave propagation
4
2.3 Nomenclature of RF bands
The table 1.1 shows the nomenclature of RF bands
Table 1.1 nomenclatures of RF bands
Band
Number
1
Symbols
Frequency Range
Wavelength Range
Example of uses
ELF
3 to 30 Hz
10,000 to 100,000 km
2
SLF
30 to 300 Hz
1000 to 10,000 km
3
4
5
6
7
ULF
VLF
LF
MF
HF
300 to 3 kHz
3 to 30 kHz
30 to 300 kHz
300 to 3000 kHz
3 to 30 MHz
100 to 1000 km
10 to 100 km
1 to 10 km
100 to 1000 m
10 to 100 m
8
VHF
30 to 300 MHz
1 to 10 m
9
UHF
300 to 3000 MHz
10 to 100 cm
10
SHF
3 to 30 GHz
1 to 10 cm
11
EHF
30 to 300 GHz
1 to 10 mm
deeply-submerged submarine
communication
submarine communication, ac power
grids
earth mode communication
near-surface submarine communication,
AM broadcasting, aircraft beacons
AM broadcasting, aircraft beacons
Sky-wave long range radio
communication: shortwave
broadcasting, military, maritime,
diplomatic, amateur two-way radio
FM radio broadcast, television
broadcast, DVB-T
television broadcast, GPS, mobile
phone communication (GSM, UMTS,
3G, HSDPA), WLAN (Wi-Fi 802.11
b/g/n), Bluetooth
DBS satellite television broadcasting,
WLAN (Wi-Fi 802.11 a/n), microwave
relays, WiMAX, radars
microwave relays, intersatellite links,
high resolution radar, directed-energy
weapon, Security screening
5
3
CHAPTER 3: SPECTRUM MANAGEMENT IN GENERAL
3.1 Introduction
Frequency spectrum management refers to various administrative and technical procedures that
are intended to ensure the operation of radio stations of different radiocommunication services at
any given time without causing or receiving harmful interference. It takes place at two levels:
national and international level. Spectrum management involves planning, allocating, assigning,
monitoring and inspection of spectrum
3.2 Objectives of Spectrum Management
·
To ensure rational, equitable, efficient and economic use of the radio frequency spectrum
by all radio communication services.
·
To maximizes spectrum use by allowing maximum number of users, while keeping
interference and congestion manageable.
·
To ensure spectrum is utilized in a manner that meets the country’s goals.
3.3 Radio Spectrum users
·
Civil Telecommunications (Fixed, Mobile & Satellite).
·
Military communications and radars.
·
Aeronautical communications and radars.
·
Maritime communications and radars.
·
Broadcasting.
·
Space Science Services.
·
Radio Astronomy.
·
Earth Exploration Satellites.
·
Amateur Radio.
·
Industrial, Scientific and Medical applications.
6
3.4 International Telecommunication Union (ITU).
Propagation of radio waves travels across national borders and therefore effective spectrum
management requires regulation starting right from international level.
International Telecommunication Union (ITU) is a specialized agency of the United Nations
which is responsible for regulation of spectrum use at the international level and in particular, its’
Radiocommunication Sector (ITU-R). Its’ rules are written by its’ member states and
administered by the ITU’s Radiocommunication Bureau (BR) and the conformity with the rules
supported by regulations at the national level.
ITU is based in Geneva, Switzerland, and its membership includes 192 Member States and
around 700 Sector Members and Associates. Kenya became a member of ITU on 11-4-1964.
In summary, the functions of ITU-R include:
·
Organize worldwide and regional exhibitions, forums and conferences on radio spectrum
management.
·
Coordinate the shared global use of the radio spectrum.
·
ensure rational, equitable, efficient and economic use of the radio frequency spectrum by
all radio communication services
·
study and adopt recommendations on radio communication matters
3.4.1 ITU Radio Regulations
The Radio Regulations are the international treaty governing the use of the radio-frequency
spectrum. They provide the overall global framework for spectrum use, including the
International Frequency Allocation Table, which allocates spectrum to broad categories of
service such as fixed, mobile, broadcasting or radionavigation.
The Radio Regulations are agreed at World Radio Conferences and Member States who do not
abide by the Regulations will not be protected from any interference for the service
concerned.[2]
7
3.4.2 ITU –R Recommendations
ITU-R Recommendations provide guidance on the use of radio spectrum by specific services and
apparatus, including technical criteria for planning coverage and avoiding interference. These
Recommendations do not have the same legal status as the Radio Regulations - they are intended
to be advisory rather than mandatory. However, most national administrations take them
sufficiently serious that they are widely acknowledged and implemented in practice. Use of these
recommendations ensures that the same methods are used in spectrum engineering practice
(including terminologies) and thus easier coordination of frequency across various countries.
3.4.3 World Radio Conferences (WRCs)
WRCs are held every two to three years. Their purpose is to review and revise the radio
regulations. Revisions are made on the basis of an agenda determined by the ITU Council, which
takes into account recommendations made by previous WRCs. [2]
3.4.4 Regional Regulatory Conferences (RRCs)
RRCs are conferences of either an ITU Region or a group of countries with a mandate to develop
an agreement concerning a particular radiocommunication service or frequency band. RRCs
cannot modify the Radio Regulations unless subsequently approved by a WRC. Final acts of
RRC are only binding on those countries that are party to the agreement. [2]
8
3.4.5 ITU Regions
The International Telecommunication Union (ITU) divides the world into three regions for the
purposes of efficient management of the global radio spectrum. Each region has its own set of
frequency allocations.
·
Region 1 comprises Europe, Africa, Middle East, Iraq, former Soviet Union and
Mongolia.
·
Region 2 covers the America, Greenland and some of the eastern Pacific Islands.
·
Region 3 comprises Asia, east of and including Iran
Figure 6.3 ITU Regions
9
3.5 Spectrum planning
Spectrum Planning is carried out to ensure efficient and effective use of the spectrum resource to
the fullest extent possible. At the international level, agreements are formed amongst nations on
spectrum use and technical specifications to aid coordination of services globally. Planning is
usually undertaken for long-term, medium-term and short-term timeframes. Long-term planning
(10 to 20 years) is required to foresee spectrum requirements far into the future. Medium-term
planning (5 to 10 years) is carried out to determine what changes should be made on spectrum
policies to meet the changing needs of users and evolving technologies. Short-term planning
(below 5 years) is carried out to make changes to spectrum policies and adjust earlier decisions.
Forecasting future spectrum use is very important if future spectrum needs are to be met. This is
normally done through projections on historical growth through monitoring of new technologies
noting their spectrum requirements and consulting with the spectrum users as they are usually in
the best position to forecast growth in their sector. It is also important to know the current uses of
spectrum as a baseline for future planning. This can be ascertained from existing records of
frequency use across the entire radio spectrum. Frequency registers and computer-automated
tools are also used to aid planning.
3.6 Spectrum engineering analysis and standards
In order to ensure electromagnetic compatibility among various services and stations, good and
sound engineering practices are essential. The following factors and standards are considered.
3.6.1 Prediction of radio wave propagation
Propagation loss is a key parameter in determination of the coverage area of the radio systems
and the extent of potential of harmful interference. In general, Basic transmission loss between
two isotropic antennas due to the dispersion of energy which takes place as the wave travels
away from the transmitter is given by the equation:
Ao = -20log10
[1.1]
(Ao= free-space attenuation (dB), λ=wavelength in kilometers, d=distance in kilometers)
10
3.6.2 Protection ratio
Protection ratio is the minimum value of the wanted-to-unwanted signal ratio, usually expressed
in dB or in dBµV/M, at the receiver input, needed to achieve a satisfactory reception quality of
the wanted signal at the receiver output. This is defined in various ITU recommendations to
ensure electromagnetic compatibility among various services. For example the protection ratio
for vision carrier from the unwanted sound carriers in TV broadcasting is -9dB, and the
minimum field strength to be protected in TV Bands IV and V is 65 dBµV/M and 70 dBµV/M
[2]
3.6.3 Transmitter equipment specification
Spectrum use state transmitter equipment technical standard requirements for the efficient use of
a specified frequency band. These standards are used in testing and certification of the
transmitter equipment. These include:
3.6.3.1 Tolerance
This is the maximum permissible departure from the center frequency of the frequency band
occupied by an emission from the assigned frequency. It is expressed in Hz. Deviation must be
small, ideally 1% of channel bandwidth or less. Table of tolerance of various
radiocommunication services in various frequency bands is given in appendix [B]
3.6.3.2 Spurious emissions
These are unwanted emissions of transmitters. They are emissions outside the necessary
bandwidth and which the level may be reduced without affecting the corresponding transmission
of information. Spurious emissions include;
·
harmonic emissions
·
Parasitic emission
·
Intermodulation product emission
·
frequency conversion products
11
generally spurious emission limit must be:
43 + 10 log (P), or 70 dBc, whichever is less stringent. Where P=carrier power [ITU]
Spurious emissions of some selected services is given in appendix [A]
3.6.4 Interference analysis
The radio regulations define interference as: “The effect of unwanted energy due to one or a
combination of emissions, radiations or inductions upon reception in a radiocommunication
system, manifested by any performance degradation, misinterpretation or loss of information
which could be extracted in the absence of such unwanted energy “[3]
Interference occurs as a result of;
·
Harmonics, spurious and parasitic emissions,
·
Co-channel interference,
·
Adjacent channel interference
·
Receiver desensitization,
·
Intermodulation products
3.6.5 Necessary radio frequency bandwidth
This is the width of the frequency band which is just sufficient to ensure the transmission of
information at the rate and with the quality required under specified conditions. The Radio
Regulation requires that RF bandwidth of emissions to be kept as small as possible to ensure
maximum frequency utilization.
The ITU-R SM. 853 gives the various formulas for determining the necessary RF emission
bandwidths of various services. For instance the necessary RF bandwidth BW for a single
channel analogue FM system is BW =2M+2D where M is the maximum modulating frequency
and D is the peak frequency deviation.[3]
12
3.6.6 Receiver equipment parameters.
3.6.6.1 Receiver sensitivity.
Receiver sensitivity is the lowest modulated carrier signal strength required to give minimum
signal to noise and distortion ratio after detection. This is measured at 12dB SINAD, in the
following relationship.
(signal+Noise+Distortion)/(Noise+Distortion)=12dB
Digital receivers suffer from the same effects as analogue receivers, but have some capacity to
reconstitute the digital signal, making effects less noticeable. “[3]
3.6.6.2 Receiver selectivity.
This is the measure of receiver ability to receive a modulated signal in the presence of modulated
signals which differ in frequency from the standard input signal frequency by a spacing of one
channel. Receiver with a high selectivity can effectively ignore the presence of out-of-band
signals“[3]
3.6.6.3 Receiver desensitization
This is the ability of a receiver to operate in the presence of a much higher power signal level for
example when a transmitter is operated close to a receiver, the relatively high signal strength
from the transmitter can overload the receiver input circuits, and reduce the sensitivity of the
receiver to wanted signals, even though the transmitter is on another frequency. In frequencies
above 30MHZ, the minimum adjacent selectivity and desensitization should be 70dB or better
measured at 12 SINAD“[3]
13
4
CHAPTER 4: SPECTRUM MANAGEMENT IN KENYA
4.1 Introduction
Frequency Spectrum management in Kenya is carried out by communications commission of
Kenya (CCK).
Functions of communications commission of Kenya
·
Establishment of national table of frequency allocations
·
Long-term spectrum management policy and planning to determine and periodically
update the existing and future requirements for the various radio communications
services.
·
Assignment of frequencies ensuring electromagnetic compatibility of all proposed or
requested assignments with regard to existing assignments on a national or international
basis.
·
Protect the country's radio communication systems from potential interference from
another country's assignments.
·
Record-keeping of frequency assignments for effective national and international
coordination, licensing and enforcement activities, policy formulation, investigations on
interference and resolution, and financial considerations.
·
Carry out radio spectrum monitoring and inspection.
4.2 National Table of Frequency Allocation
Kenya has developed its own table of frequency allocation within the framework of the ITU's
Radio Regulations. This table allocates a given frequency spectrum band to a given service for
example fixed, mobile maritime or aeronautical. This is one of the first steps in long and
medium-term planning. Once a national frequency allocation table has been developed, further
sub-allocations of use are often made in order to group similar technologies and similar users in a
given frequency band. Greater spectrum efficiencies are obtained when uses with similar
technical parameters share the same frequency band, for instance lumping high power
applications with other high power applications.
14
4.3
Mechanisms for dividing up access to spectrum.
Frequency spectrum is a limited natural resource. There is a higher demand than supply and
therefore accommodating many users calls for frequency band sharing. The following are
various techniques employed to achieve frequency band sharing.
·
Geographical sharing
In this case a user is given a license to transmit on part of the country. A different user is given a
license to use the same frequencies in a different part of the country. The two users needs to be
sufficiently far apart so that they will not interfere with each other on the boundary of their
operations. In practice, this implies either a guard zone between coverage areas or some
restrictions on emissions near the boundary.
·
Band sharing
In this case, different users are allowed in the same spectrum. A typical example is satellite
transmission and fixed links. Because both users have directional antennas and as the satellite
antennas point somewhat vertically whereas the fixed link antennas point horizontally, there is a
fair degree of isolation between them. However, it is still necessary to maintain some
geographical separation.
4.4
SPECTRUM PRICING
Spectrum is a resource that can be traded and priced like any other resource commodity.
In 1993 the ITU recommended that all spectrum users should pay a charge and a set of principles
should be followed and that: [6]
·
The pricing structure should be clear, transparent and comprehensive.
·
Spectrum charge should be calculated fairly. If two users are using the same amount of
spectrum in the same way, both should pay the same charge.
·
Spectrum charge should be proportional to the amount of bandwidth used.
·
The charges should reflect the spectrum’s value to the society, i.e. if need be, frequencies
used for public services should be subject to lower charges.
·
Spectrum users should be consulted about any intended adjustments in spectrum
charges.
·
The pricing structure should reflect the scarcity of available spectrum and the level of
demand for spectrum in different frequency bands.
15
4.4.1 Spectrum pricing requirements.
Spectrum prices or charges are set to recover the cost of running a spectrum regulatory agency.
The resources the spectrum management agency requires include: skilled labour, IT resources,
investment in technical monitoring equipment, and expenditures to pay for participation in ITU
and other international meetings. Administrative methods of setting spectrum prices are
increasingly being supplemented by the use of market based methods for determining spectrum
prices.
In summary, the following are requirements of spectrum pricing:
·
To cover the costs of spectrum management activity borne by the spectrum management
authority or regulators.
·
To encourage existing users to relinquish unused spectrum allocations
·
To Act as incentive to consider alternatives to radio spectrum use, so freeing congested
spectrum space.
·
Increase the probability of new users gaining access to the spectrum
·
Providing revenue to the government
16
4.4.2 Annual Current frequency spectrum fee schedule in Kenya
Table 2.4
SERVICE
DESCRPTION
ANNUAL FEES PER
STATION PER
FREQUENCY IN KSH.
MF/HF
VHF/UHF
A license to establish a
radio station for carrying
radio communication with
aircraft station
4,800
4,800
A license to establish a
mobile station aboard an
aircraft to operate in the
aeronautical mobile
service.
4,800
4,800
3.LICENSE FOR FIXED
STATION OPERATING
IN MOBILE SERVICE
A license to establish a
radio communication
station at a fixed location
for carrying on a mobile
Radio communication
18,700
5,000
4.MOBILE STATION
LICENSE
A license to install and use
radio apparatus for
transmitting and receiving
aboard a vehicle , aircraft
or a ship
5,610
2,900
A license to establish a
portable radio
communication apparatus
to operate in the mobile
service.
5,610
2,900
A license to establish a
station and a land for
carrying on a service with
ship stations.
5,610
2,900
1.AERONAUTICAL
STATION LICENCE
2.AICRAFT STATION
LICENSE
5.PORTABLE
STATION LICENSE.
6.COAST STATION
LICENSE
17
7.SHIP STATION
LICENSE
8.RADIO AMATEUR
LICENSE
9.CITIZEN BAND
RADIO LICENSE
10.PRIVATE PAGING
SERVICE
11.PUBLIC PAGING
SERVICE
12.RADIO PRESS
RECEPTION LICENSE
A license to install and
use radio apparatus aboard
ships
5,610
2,900
A license to install and
operate an amateur radio
station
2,000
2,000
A license to operate a low
power radio apparatus
operating in the frequency
bands 26925KHZ to
27403KHZ
Not
applicable
1,000
A license to operate a
radio paging service for
private use
Not
applicable
A license to operate a
radio paging service for
public use (base station)
Not
applicable
A license to establish a
radio station to receive
press message from
stations transmitting multidestination radio press
messages
25,000
140,000
10,000
10,000
13.Alarm systems
The basic charge for each unit is Kshs.1250, but the specific charge for each particular customer
is determined by using the maximum value in each grouping of 5; 5 for 1-5, 10 for 6-10, 15 for
11-15.
14.Fixed satellite earth stations
The fee payable for fixed satellite earth stations is commensurate with the power and the
occupied bandwidth and calculated on the basis of these parameters using the following formula;
A fee per transmitter or carrier in Kenya shillings is given by;
18
Fee ( KShs). = k1log10 Pnom (watts) + k2log10 (Ptot-1000) × BW(KHz)× 574.10
‘
25 watts
25 watts
8.5KHZ
(4.1)
Where;
K1=1 for the first 1KW of radiated carrier power.
K2 =0.2 for additional power above 1KW.
25 watts is the maximum power allowable for VHF base stations.
8.5KHZ is the maximum allowable RF bandwidth for VHF base stations.
Pnom is the nominal transmitter power.
Ptot is the total effective radiated power in watts.
15. Table 3.4 Broadcast stations fee per transmitter
Service
Amount in KShs.
ERP power conditions
15.1. Television broadcasting
360,000
ERP power ≤10KW
As per formula (4.2) subject to a
minimum of KShs. 360,000
ERP power >10KW
30,000
ERP power ≤2KW
65,000
2KW<ERP power ≤5KW
130,000
5KW<ERP power ≤ 10KW
As per formula (4.2) subject to a
minimum of KShs. 130,000
ERP power >10KW
15.2.Radio broadcasting
Fee (KShs)=
‘
K1log10 Pnom(watts) + K2log10 (Ptot - 1000) × BW(KHz) × 574.10 × K3
25 watts
25 watts
8.5KHz
(4.2)
Where;
K1=1 for the first 1KW of radiated carrier power.
K2 =0.2 for additional power above 1KW.
25 watts is the maximum power allowable for VHF base stations.
8.5KHz is the maximum allowable RF bandwidth for VHF base stations.
Pnom is the first 1KW of the effective radiated power (ERP). .
Ptot is the total effective radiated power in watts.
19
K3=0.4 for TV broadcasting stations
=5 for Radio broadcasting stations
16. Terrestrial links (fixed station license)
The fee (KShs.) per transmitter per location is given by;
Fee (KShs.) = RF bandwidth (KHz) x Number of
8.5 KHz
RF channels
× K1 x 574.10
(4.3)
Where;
Unit fee= KShs.574.10 for a 8.5KHz band
K1=0.6 for frequency band <1700MHz
=0.5 for frequency band 1700MHz to 10000 MHz
=0.4 for frequency band >10000MHz
17 Mobile cellular networks
17.1 Exclusive spectrum assignment Bandwidth
This is applicable to cases that have been assigned exclusive use of a specific bandwidth
countrywide. This standing fee is to be paid annually for exclusive use of the bandwidth in
addition to the usage fee that is detailed in equation (4.5)
Fee (KShs)= assigned bandwidth (KHz) × weighting factor × 1043.65
‘
(4.4)
8.5 KHz
Where;
Weighting factor to be used =6
Unit fee = KShs.1043.65
17.2 spectrum usage fees
This is based on actual usage of the spectrum and depends on the number of TRXs in the
network.
Fee (KShs.) =43,000 × n
(4.5)
Where;
20
n is the actual or equivalent number of 200KHz duplex TRXs estimated to be in use at the end of
the year in review
8.5KHz is the maximum allowable RF bandwidth for VHF base stations
Annual spectrum management cost of one TRX is KShs.43,000
18 Fixed wireless access networks
18.1 exclusive spectrum assignment bandwidth
Fee (KShs.) = assigned bandwidth (KHz) × weighting factor × 1043.65
‘
8.5 KHZ
(4.6)
Where;
Weighting factor to be used =6
Unit fee =KShs. 1043.65
18.2 Spectrum usage fees
This is based on actual usage of the spectrum and depends on the number of TRXs in the
network
Fee (KShs.) =100,000 × n × K1
(4.7)
Where;
n is the actual or equivalent number of 1.75MHz duplex TRXs estimated to be in use at the end
of the year in review
Annual spectrum management cost of one TRX is KShs. 100,000
Weighing factor K1=0.8 for f<1GHz
=0.7 for 1GHz ≤ f<6GHz
=0.6 for 6GHz ≤f<10GHz
=0.5 for 10GHz≤f< 20GHz
=0.4 for ≥20GHz
21
19 Trunked networks (mobile trunked radio license)
19.1
Exclusive spectrum assignment bandwidth
Fee (KShs.) = assigned bandwidth (KHZ) × K× 1043.65
‘
8.5 KHZ
(4.8)
Where;
K =6 Weighting factor to be used
Unit fee=KShs. 1043.65
19.2 spectrum usage fees
This is based on the actual usage of the spectrum and depends on the number of TRXs in the
network
Fee (KShs.) =43,000 × n × K1
(4.9)
Where,
n is the actual or equivalent number of 25KHz duplex TRXs estimated to be in use at the end of
the year in review
Unit fee = KShs.43, 000 for Annual spectrum management cost of one 25 KHz duplex
transmitter.
K1=1 for trunked public access mobile radio (PAMR) systems
=3.5 for trunked private mobile radio (PMR) systems
20. Single channel radios
The fee per transmitter per location is given by;
Fee (KShs.) =
‘
RF Bandwidth (KHz) ×1043.65
8.5KHz
(4.10)
22
4.5 SPECTRUM AUTHORIZATION
Authorization is the process by which users are assigned spectrum resource and given license to
transmit on a specific frequency or on a band of frequencies. Spectrum authorization activities
include analyzing requirements for proposed frequencies in accordance with national plans and
policies for frequency allocation and protecting radiocommunication systems from harmful
interference. Spectrum authorization strategies are used to ensure proper use, facilitate reuse and
to ensure effective global coordination of the limited spectrum resource, national frequency
allocations must be consistent with;
·
ITU Radio Regulations
·
ITU Frequency Plans
·
ITU-R Recommendations
·
National legislation and operating procedures
4.5.1 Parameters notified to ITU-R after assigning spectrum to a user
·
Site name
·
Directivity of the antenna
·
Height of the antenna
·
Effective antenna height in different azimuth
·
Attenuation at different azimuth
·
Site geography coordinates
·
Altitude
·
Frequency
·
Necessary bandwidth
·
Polarization
·
Effective radiated power
·
Transmission system
23
This parameters will be registered in the Master International Frequency Register at the ITU
headquarters so that they will be referred to during international frequency co-ordination.
4.5.2 Administrative Methods of assigning spectrum
Administrative method is a process whereby the regulator specifies detailed rules and constraints
affecting how, where and when spectrum can be used and who can access it. Often it has
involved specifying what equipment a licensee can use and at what power levels. This is a good
way to control interference. However, these methods are often slow and unresponsive to new
technological opportunities.
In the administrative method there are two stages involved in authorizing spectrum use:
·
The allocation stage; and
·
The assignment stage.
At the allocation stage, broad decisions on spectrum use are made on global and regional ITU
radiocommunication conferences. The national spectrum regulator (CCK) prepare frequency
allocation table on this basis, which usually impose further restrictions on spectrum use.
Potential users make proposals for allocations. Once allocation has been determined, spectrum
use is authorized at the assignment stage with the issuance of a license
4.5.2.1 First come, first served basis
First come, first served approach works best when the demand for spectrum is unlikely to exceed
the supply. This is because there is no mechanism to ensure the spectrum is assigned to more
efficient or higher value users. Sometimes this approach is used in circumstances where demand
may exceed supply. First come, first served approach is currently used in Kenya to assign
spectrum in bands for point-to-point links and private mobile radio, both of which tend to
involve many small users of spectrum, with bespoke spectrum requirements and whose demands
can change from year to year. In these circumstances, this approach provides a flexible approach
to assigning spectrum with low transaction costs compared with the alternatives of auctions or
comparative tenders.
In bands where congestion arises, the spectrum regulator will have few options for promoting
more efficient use of the spectrum. Administrative incentive pricing should have a role to
encourage the reassignment of spectrum from low to high value users.
24
In practice, the national spectrum regulator do not literally assign spectrum to whoever demands
it under the first come first served approach, but rather use administrative rules to determine the
frequencies and bandwidth an applicant is permitted. These include rules related to optimizing
the use of frequencies.
4.5.2.2 Comparative Selection
Comparative refers to a process whereby licenses are assigned to the best qualified of the
competing applicants. Key issues in the design of comparative selection procedures are the
criteria used to choose the winning applicant, the precision and transparency of the criteria, the
weighting given to different criteria and the transparency of reasons for the final decision. In
most countries comparative selection procedures happen behind closed doors with decisions
made by a committee. These hearings are time consuming, expensive and are criticized for
assigning licenses based on insignificant and arbitrary differences. In some circumstances
applicants can only guess at what is required in putting together their bids and outcomes can be
subject to undue influence. The winning bidder is therefore unlikely to be the most economically
efficient supplier. Opaque comparative selection processes are also susceptible to legal challenge
which can in turn lead to long delays in awarding licenses and substantial loss of economic
welfare. Comparative selection was used in assigning spectrum to digital signal distribution for
digital broadcasting.
4.5.3 Market Methods
Attention has recently been focused on creating genuine markets for spectrum licenses under
which both the ownership and use of spectrum can change in the course of a licensee's operation.
4.5.3.1 Spectrum Trading
Spectrum trading is a mechanism whereby rights and any associated obligations to use spectrum
can be transferred from one party to another by way of a market-based exchange for a certain
price. The right to use the spectrum is transferred from one user to another and a sum is paid by
the new user for spectrum. Spectrum trading contributes to efficient use of spectrum because a
trade will only take place if the spectrum is worth more to the new user than it was to the old
user, reflecting greater economic. Spectrum trading includes;
·
Leasing of rights to a third party for a specified period of time
25
·
Change of ownership
·
Change of ownership, reconfiguration and change of.
4.5.3.2 Auctioning
Auctions involve assigning licenses to those who bid the largest sums of money and often
applicants are only eligible to bid if they pass certain pre-qualification tests like relating to
technical and financial competence. In addition, non-monetary requirements may be specified in
license conditions requiring licensees to provide particular services like for broadcasting services
licenses may specify the program formats, minimum amounts of programming of certain types or
coverage obligations. Auctioning ensures that any newly released spectrum into the market is
acquired by those who value it the most. Spectrum auctions have the following advantages;
·
Efficiency: the assignment of licenses leads to licenses being awarded to those who
value it the most and those who contribute the most to economic activity through using
spectrum.
·
Competition: spectrum rights are issued in a way that helps promote effective
competition.
·
Transparency: ensures that the process of selection is without corruption and
undertaken expeditiously
4.5.4 Current spectrum utilization in Kenya [source CCK database]
· Government
- Major user of all bands.
26
· Telkom
- 387 links for public telephony; 2GHz, 4GHz, 6GHz, 7GHz, 8GHz and 10/11GHz.
- 45 radio links for medium capacity public telephony traffic (60-120 channel capacity)
in 400MHz and 800MHz band.
- 42 low capacity (12-24channels) 230MHz and 450MHz band.
- 243 WLL trunked rural access systems.
- 122 single channel capacity VHF radio links.
- Two satellite C-band (4/6 GHz) earth stations at longonot and Kericho.
·
Safaricom
- GSM 890-900/935-945MHz,
1740-1750/1835-1845MHz .
- Backhaul links.
- 6/7 GHZ: 144 links.
- 8GHZ: 88links.
- 13GHZ: 12 links.
- 15GHZ: 346 links
- 18GHZ: 2links
- 26GHZ: 13links
·
Airtel
- GSM 900-910/945-955MHZ
1720-1730/1815-1825MHZ.
- Backhaul links.
27
- 6/7GHZ: 95links.
- 15GHZ: 281links.
- 26GHZ: 326links.
·
VSAT
- 5 commercial VSAT operators.
- 79 private VSAT operators.
·
Local loop operators
- 14 LLO’s assigned spectrum mainly in the 1900MHz band.
·
Public data network operators
- 16PDNO’s assigned frequencies mainly in the 3.5GHz as well as 5.8GHz ISM band for
their access network.
·
Broadcasting
- Television: 119 channells,57 on air and others in various stages of implementation
- 294 FM stations, KBC :MF services at 11 locations countrywide, HF from Komarock and
Langat
Most of these FM radio stations and television channels do not transmit nationally but
transmit within major towns and local areas on frequency reuse scheme.
·
Private radio networks
- HF and VHF: 3,641 private radio networks with 4,795 base stations and 22,874 mobile
and portable stations
- 611 Aircraft stations
- 90 radio amateur
28
·
Aeronautical services
- 115 radio networks countrywide for radio navigation, distress and safety, radars,
intra-communication,
·
Maritime services
- Kenya maritime and Kenya Ports Authority: Extensive VHF network ,
156-162MHz for ship calling frequencies, port operations, ship-to-ship
communications, ship-to-shore, distress and safety, search and rescue
[source CCK database]
4.5.5 Unlicensed Spectrum
Unlicensed Spectrum is a free band where anyone can transmit without a license while
complying with the rules that are designed to limit interference. Industrial, Scientific and
Medical (ISM) band is an example of unlicensed spectrum band but with some management in
terms of power restrictions on individual users. Significant innovations have emerged in these
band like BlueTooth, Wi-Fi and W-LAN in the 2.4 GHz which have led to call for management
of it.
29
4.6 Spectrum monitoring and inspection
Effective spectrum monitoring processes support activities centered on making interference-free
assignments and includes the use of data and electromagnetic compatibility (EMC) verification
activities. As well, monitoring and compliance activities are needed to ensure user compliance
with both license conditions and technical standards. Furthermore, spectrum use planning and
resolution of spectrum scarcity issues can be accomplished through study and analysis of
spectrum occupancy data. Understanding the level of spectrum use or occupancy in comparison
to assignments is important for efficient use of the spectrum resource.
In summary, the following are objectives of spectrum monitoring:
·
To ensure compliance with the national and international spectrum management
regulations to shape and sustain radio environments and user behavior, maximizing the
benefit of the spectrum resource to the society
·
Identifying and locating of known or unauthorized transmissions.
·
To support in spectrum engineering analysis including validation of tolerance levels,
spurious emissions, determining the probability of interference and development of
band-sharing strategies.
·
Improving spectrum efficiency by determining actual frequency usage and occupancy,
assessing availability of spectrum for future uses.
·
To determine frequency bands experiencing congestion, interference or coordination
problem.
·
Investigate and identify stations causing interference.
·
Provide statistics on use of spectrum.
Frequency spectrum monitoring is normally done through compliance returns, inspections or
using of monitoring tools and instruments.
4.6.1 Spectrum Monitoring Technology
Fixed, remote and mobile monitoring equipment are combined to provide tools for monitoring.
Monitoring equipment and integrated software tools are very complex and expensive.
Fortunately, advances in computerization, monitoring technology, and security techniques have
permitted greater use of remote unmanned monitoring techniques involving integrated spectrum
30
observations. The types of monitoring equipment include; antenna, spectrum analyzers, and radio
direction-finding equipment (RDF). These types can further categorized by frequency range (HF,
VHF and UHF.) and signal type (analogue or digital). Simple systems for VHF/UHF monitoring
can be comprised of several fixed antennas, receivers and spectrum analyzers.
4.6.2 Monitoring Equipment
Antennas
An antenna is simply an electronic component designed to transmit or receive radio waves.
Antennas are linked to either radio receivers or signal generators of direction-finding equipment.
Different antenna types are needed for different coverage of the frequency ranges. Examples of
different antenna types are depicted below.
Figure 7.4 monitoring antenna with vertical dipole Direction finding antennas
Figure 8.4mobile monitoring station
31
Spectrum Analyzers
Since different frequencies are allocated to various radio services, it is important that each
service operate at the assigned frequency and within the allocated channel bandwidth. Due to
scarcity of spectrum, transmitters should be planned to operate at closely spaced adjacent
frequencies. Common measurements taken by a spectrum analyzer include frequency, power,
modulation, distortion, and noise. Understanding the spectral content of a signal is important,
especially in systems with limited bandwidth. In digital modulation techniques, there are
additional measurements which need to be taken, these are error vector magnitude (EVM) and
phase error versus time.
The types of spectrum analyzers used are: Fourier and Vector Signal Analyzers.
Fourier signal analyzers measure the time-domain signal and then use digital signal processing
(DSP) techniques to perform a fast Fourier transform (FFT) and display the signal in the
frequency domain showing both phase as well as magnitude of the signal.
Vector signal analyzers (VSA’s) operate like Fourier signal analyzer but offer faster, higherresolution spectrum measurements, demodulation, and advanced time-domain analysis.
Radio Direction-Finding Equipment
Radio Direction-Finding, is the technique for determining the direction of a radio transmission.
Radio direction-finding uses triangulation method to determine the location of a radio
transmission and also locate the source of radio frequency interference.
There are two common technical approaches to radio direction-finding. The first approach
involves the use of directional antennas which are designed to be more sensitive to signals
received in some directions rather than in others. As the antenna is turned in various directions, a
signal being received will either increase or decrease in strength. The direction in which the
signal is strongest is the likely direction in which the radio transmitter is located. The movement
of the antenna and the determination of the peak signal strength can be made by a human
operator or can be done automatically by electronics.
The second approach exploits the effects of phase shift. Fixed antennas are deployed in a precise
geometric pattern and electronics system switches between the antennas very rapidly. By
computing the amount of phase shift present on the signal from antenna to antenna, a direction to
the signal source can be computed.
32
Figure 9.4Image of triangulation location of a transmitter
4.6.3 Designing Spectrum Monitoring Systems
State-of-the-art spectrum monitoring equipment is highly integrated. Integration typically
involves the use of graphical user interface (GUI) based spectrum management tools and systems
which are specifically designed to operate multiple electronic components simultaneously and
remotely over data protocols such as TCP/IP. This allows for an integrated network system for
management of the radio spectrum using remote devices. Remote devices permit access to
monitoring equipment from anywhere through compatible computer, a modem and a telephone
line or network connection (LAN or WAN). There are organizational and functional aspects to
architecting spectrum monitoring systems. Organizational components include centralized,
regional and remote locations for siting of monitoring equipment in stations and operational
staffing or use of unmanned remote capabilities. Functional components of spectrum monitoring
systems include: central monitoring control; operational consoles for operation of equipment and
analysis of data; data networking and management systems for data communications. Remote
devices can be controlled in several ways:
·
Locally from the server;
·
Remotely across a LAN;
·
Modem over a WAN.
33
4.6.4 Spectrum monitoring capabilities in Kenya.
The following are monitoring stations in the country with various monitoring capabilities.
·
Four fixed monitoring stations with VHF/UHF capability in Kabete, Industrial area,
Mazeras and Mombasa and one fixed monitoring stations monitoring stations with HF/
VHF/UHF capability in Kahawa,
·
Two remote monitoring stations with HF capability in Kitale and Garissa.
·
Two mobile monitoring stations with HF/VHF/UHF/SHF capabilities.
The above systems are fully integrated through a communications network that utilizes leased
digital data lines, microwave links, HF links, Dial up PSTN and GSM lines to enable remote
control and monitoring from national spectrum monitoring and control centre headquarters at
Kabete.
4.6.5 Radio spectrum management and monitoring system layout in Kenya
34
CHAPTER FIVE: IMPACT OF INTRODUCTION OF DIGITAL
BROADACSTING ON SPECTRUM UTILIZATION IN KENYA.
5
5.1
Introduction
Broadcasting is a key component of information and communications infrastructure in Kenya. Its
operations are guided by a strong public interest requirement. Scarcity of frequency spectrum
due to congestion in the bands has hindered this sector from expanding in terms of ownership
and diversity. In the digital era there will be opportunities for television and radio to grow in
relevance and diversity of services.
Digital terrestrial broadcasting plan was established at the Regional Radiocommunications
Conference (RRC-06) in Geneva in 2006. The conference discussed planning of digital
broadcasting and Kenya participated actively in this forum. Digital broadcasting uses digital
rather than analogue waveforms to carry broadcasts over assigned radio frequency bands. Sound
and pictures are processed electronically and converted into digital format. This format is then
transmitted as a bit stream and reconverted by appropriate receivers or set-top boxes into sound
and TV programmes. The RRC-06 established the Digital terrestrial Broadcasting Plan in the
174-230 MHz and 470-862 MHz band. However, in Kenya, the transition to digital broadcasting
will be implemented in the 470-806 MHz band. As the existing analogue television services in
the 174-230 MHz band move to digital broadcasting in the 470-806 MHz frequency band, the
later frequency band will be available for the introduction of T-DAB and DVB-T2 services.
RRC-06 set 17 June 2015 as the deadline for transition from analogue to digital terrestrial
television broadcasting. [4]
Table 4.5 of bands for broadcasting Services and the planned digital service.
Band
Frequency
Current Service
Planned
Digital Service
VHF/UHF
174 - 230 MHz
VHF TV Band III
T-DAB, DVB-T2
470 - 806 MHz
UHF TV
DVB-T2,
Source: http://cck.go.ke/about/downloads/migration_digital_tv.pdf
35
5.1.1 Current Broadcasting Situation
5.1.2 Analog FM broadcasting analysis
According to Carson’s rule, FM channel bandwidth (BW) is given by
BW = 2(Δf + fm)
Where;
Δf is the peak frequency deviation
fm is the highest frequency in the modulating signal.
According to ITU annex J table, FM sound broadcasting
Δf = 75 KHz,
fm = 15 KHz
Therefore BW=2(75 KHz+15 KHz)=180 KHz
From the table of national frequency allocation, fm broadcasting is allocated the band between
87.5-108 MHz
This gives bandwidth of 108 MHz-87.5 MHz=20.5 MHz
In Kenya, a single FM broadcasting station is allocated RF channel bandwidth of 200 KHz, with
adjacent transmitters located at 400 KHz apart. This implies that a single FM station is allocated
a total RF channel bandwidth of 400 KHz.[3]
Therefore total number of FM channels that can be accommodated in this bandwidth in the same
region at the same time is given by;
FM stations
.
.
=51.25≈51 stations
In Nairobi alone this band is already fully occupied and therefore no new FM station can be set
up.
5.1.3 Analogue television broadcasting analysis
From the table of national frequency allocation, television broadcasting has been allocated the
band between 174-230 MHz in the VHF band and the band between 470-862 MHz in the UHF
band but currently 806-862 MHz band has been assigned for fixed links ,fixed wireless and
mobile services.[Kenya national table of frequency allocation,3]
Therefore the total bandwidth available for television broadcasting in the VHF band is given by;
36
230 MHz-174 MHz=56MHz bandwidth
And in UHF band is given by;
806 MHz-470 MHz=336MHz bandwidth
Currently in Kenya, a single television broadcasting station is allocated a channel bandwidth of 7
MHz in the VHF band and 8 MHz in the UHF band.[3,5]
Therefore the total number of television channels that can be accommodated in the 56MHz
bandwidth in the VHF band in the same region at the same is given by ;
Television ℎ
=
=8
While in the UHF band in the same region is given by;
Television ℎ
=
=42
Therefore the total number of television
5.2 Digital Terrestrial Television
Kenya had adopted terrestrial digital video broadcasting (DVB-T) with MPEG-4/AVC
compression technique standard in accordance with the decisions taken at RRC-06 but so far
DVB-T2 (second generation of DVB-T) has been developed and the government has opted to
adopt it. DVB-T2 uses orthogonal frequency division multiplex (OFDM) modulation scheme just
like DVB-T. This type of modulation uses a large number of sub-carriers, delivering a robust
signal that has the ability to deal with very severe channel conditions. [4]
37
Table 5.5 Comparison of parameters between DVB-T and DVB-T2
DVB-T
DVB-T2
Code rate
1/2, 2/3, 3/4, 5/6, 7/8
1/2, 3/5, 2/3, 3/4, 4/5, 5/6
Modulation
QPSK, 16QAM, 64QAM
QPSK, 16QAM, 64QAM, 256QAM
Guard Interval
1/4, 1/8, 1/16, 1/32
1/4, 19/256, 1/8, 19/128, 1/16, 1/32,
1/128
FFT size
2K, 8K
1K, 2K, 4K, 8K, 16K, 32K, 32K
Scattered pilots
8% of total
1%, 2%, 4%, 8% of total
Continual pilots
2.6% of total
0.35% of total
Bandwidth (MHz)
5, 6, 7, 8
1.7, 5, 6, 7, 8, 10
Source: http://tech.ebu.ch/docs/r/r124.pdf
Table 6.5 Number of television programmes per multiplex (8 MHz channel) for fixed
reception with DVB-T, 16-QAM,code rate2/3,FFT 8K,Guard interval 1/4 and DVB-T2
with16-QAM,code rate 5/6, FFT 16K,Guard interval 1/8 [6]
Television Format
Compression method
No. of programmes
DVB-T
No. of programmes
DVB-T2
SDTV
MPEG-4/AVC
9
13
HD-720p
MPEG-4/AVC
3
4
HD-1080i
MPEG-4/AVC
2
4
Source: http:// tech.ebu.ch/docs/techreview/trev_2009-Q4_Spectrum_Brugger.pdf
5.2.1 DVB-T2 analysis
Using DVB-T2 with MPEG-4/AVC coding with FFT 16k, 16-QAM, code rate 5/6, Guard
Interval 1/4 in one 8 MHz channel as per the table 6.5, the total number of television
programmes that can be transmitted in UHF band (470-806MHz) is given by.
Total bandwidth=806MHz-470MHz=336MHz
38
RF channels (8 MHz) =
= 42
Therefore total number of SDTV programmes that can be transmitted in this band is given by;
42×13=546 television programmes
While total number of HD-720p or HD-1080i television programmes that can be transmitted in
the same band is given by;
42× 4=168 television programmes
The VHF band (174MHz-230 MHz) will be shared between T-DAB and DVB-T depending on
the growth of the broadcasters.[4]
5.2.2 Digital Terrestrial Radio
Kenya adopted T-DAB in accordance with the decisions taken at RRC-06 as a standard for
digital sound broadcasting, this will be introduction as a new service and not considered a
transition, as it is planned to be introduced in the 174 – 230 MHz frequency band.[4]
5.2.2.1 Terrestrial Digital audio broadcasting (T-DAB)
Terrestrial Digital audio broadcasting uses Orthogonal Frequency Division Multiplex (OFDM).
By means of OFDM, the information to be transmitted is distributed over 1536 carriers at a 1
kHz spacing thereby occupying a bandwidth of 1.536MHz with a bitrate of 1152kbit/s. DAB
uses MPEG Audio Layer 2 audio compression technology which provides a capacity reduction
factor of 6, needing only a bitrate of 192 Kbit/s for a single programme. This audio compression
technology provides DAB with the ability to fit upto 6 stereo music programs in the bandwidth
of 1.536MHz. [7]
5.2.2.2 Comparison of T-DAB and Analog FM broadcasting spectral efficiency
Analog FM spectral efficiency
Analog FM frequency reuse is approximately 15, meaning that only one out of 15 transmitter
sites can use the same channel frequency without problems with co-channel interference and a
single programme occupies a bandwidth of 0.2MHz.
Reuse factor =
39
Therefore spectral efficiency of analog FM broadcasting is given by
=
×
=
×
.
= 0.33
programmes/transmitter/MHz [3]
T-Dab spectral efficiency
T-DAB with 192 Kbit/s codec requires
.
×
/
/
= 0.256 MHz per audio
programme.
1.536MHz=channel bandwidth
192 Kbit/s=compressed bitrate
1152 Kbit/s= T-DAB bitrate before compression
The frequency reuse factor for local programmes and multi-frequency broadcasting networks
(MFN) is typically 4, resulting in ×
.
= 0.976 programmes/transmitter/MHz this is 2.96
times as efficient as analog FM for local stations. This means that it will be possible to increase
the number of radio stations by a factor of at least 2 compared with analog FM.
For single frequency network (SFN) transmission, the channel re-use factor is 1, resulting in
×
.
= 3.91 programmes/transmitter/MHz, which is 11.8 times as efficient as analog FM,
resulting in increase of number of radio stations by a factor of atleast 11 compared with analog
FM.[7]
Therefore T-DAB gives substantially higher spectral efficiency, measured in programmes per
MHz and per transmitter site, than analogue communication.
40
5.2.3 Benefits of Digital Broadcasting.
The benefits of migrating from analogue to digital terrestrial broadcasting are:
•
Accommodation of more programme channels in one analog RF channel.
•
Greater spectrum efficiency due to associated digital coding techniques.
•
Unlike analogue services, digital terrestrial services are carried in multiplexes.
•
Maximizes use of infrastructure thus lowering transmission costs
•
Higher video and audio quality;
•
The switch-off of analogue terrestrial broadcasting will release some frequency spectrum
(digital dividend) in the VHF and UHF frequency bands for reassignment to other
services.
5.2.4 Digital Signal distribution
Broadcasting in Kenya has evolved with broadcasters developing their own individual
transmission infrastructure. The introduction of digital broadcasting service in Kenya will be
facilitated through licensed signal distributors which will make sure their infrastructures are
available for hire by communication transmission services. This will give room to the
introduction of Single Frequency Network distribution which will ensure optimum utilization of
spectrum. The signal distribution of broadcasting signals should be done by a separate entity
from the broadcasters. [4]
5.2.5 Single Frequency Network distribution.
The use of OFDM modulation with the appropriate guard interval allows T-DAB or DVB-T2 to
provide a single frequency network (SFN). SFN is a network where a number of transmitters
operate on the same radio frequency. In this case the signals from each transmitter in the SFN
needs to be accurately time-aligned, which is done by sync information in the stream and timing
at each transmitter referenced to GPS. The aim of SFNs is efficient utilization of the radio
spectrum, allowing a higher number of radio or TV programs to be transmitted compared to
traditional analogue multi-frequency network (MFN) transmission. SFN can cover the whole
country. [8]
41
The fig below illustrates Multiple Frequency Network (MFN) with three different
transmitters using different frequencies, with 24 MHz bandwidth occupied to carry the same
TV programme channel in contrast with single Frequency Network( SFN), only one
frequency, with bandwidth optimization: only 8 MHz
MFN
Frequency 470 MHz
Bandwidth 8
SFN
Frequency 478 MHz
Bandwidth 8
Frequency 470 MHz
Bandwidth 8
Frequency 486 MHz
Bandwidth 8
Single Frequency Network Requirements
Transmitters in one SFN cell should:
·
Radiate over the same frequency
·
Synchronized with each other
·
transmit identical data streams
42
6
CHAPTER 6: CONCLUSIONS RECOMMENDATIONS
6.1 Conclusions and Recommendations
The study of frequency spectrum management was successfully carried out and it was observed
that;
Frequency spectrum should be managed transparently to promote efficiency, reliability and
accountability.
Digital broadcasting is more spectrum efficient compared to analog broadcasting and transition
to digital will release some spectrum in VHF and UHF band as a digital dividend after the
switch-off of analog broadcasting. This spectrum will be available to use for a number of
application that could include wireless access systems, cellular operators and datacasting. A
decision has not been taken on the actual assignments of the freed spectrum and is under
discussion in ITU for possible worldwide allocation.
Administratively pricing formulas should be revised to cater for users in the rural areas with less
population density and less purchasing power because with same pricing countrywide they will
be penalized. This problem should be solved through a zoning formula.
Some spectrum owned by government is underutilized and occupies critical parts of the spectrum
that private sector crave for to provide broadband wireless access. This include the spectrum
within 2.3-2.7 GHz and 400 and 800Mhz.[6].
Spectrum sharing should be encouraged among various services and users to cater for the
scarcity of spectrum.
Market-based mechanism of assigning spectrum like auctioning should be used where demand
for radio spectrum use is rising fast.
Digital broadcasting should be introduced in the current analog short wave and medium wave
broadcasting to promote more efficient utilization of spectrum.
Other transmission media like fiber-optic cables should be encouraged to help decongest already
congested bands.
43
REFERENCE
[1] Radio Wave Propagation for Telecommunication Applications by H. Sizun
[2] John Burns, Philip Marks, Florence Leborgne “European commission “study on spectrum
management in the field of broadcasting,2004, volume number 1514/ECB/ANX/3,
page number 7-10
[3] Radio Regulations edition 2
[4] Report on migration of terrestrial television to digital broadcasting in Kenya [Retrieved from
http://cck.go.ke/about/downloads/migration_digital_tv.pdf]
[6] http://www.itu.com
[7]http://www.promax.es/downloads/docs/pdf/DABHistory-English.pdf
[8]http://tech.ebu.ch/docs/techreview/trev_2009-Q4_Spectrum_Brugger.pdf
[9]http://igorfuna.com/dvb-t/
44
7
APPENDIX
APPENDIX A: Table of maximum permitted power levels for spurious emissions
Service category
Attenuation (dB) below the power
supplied to the antenna transmission line
Space services (earth stations)
43 + 10 log (P), or 60 dBc, whichever is less stringent
Space services (space stations)
43 + 10 log (P), or 60 dBc, whichever is less stringent
Radiodetermination
43 + 10 log (PEP), or 60 dB, whichever is less stringent
Broadcast television
46 + 10 log (P), or 60 dBc, whichever is less stringent,
without exceeding the absolute mean power level of 1 mW
for VHF stations or 12 mW for UHF stations.
Broadcast FM
46 + 10 log (P), or 70 dBc, whichever is less stringent; the
absolute mean power level of 1 mW should not be
exceeded
Broadcasting at MF/HF
50 dBc; the absolute mean power level of 50 mW should
not be exceeded
SSB from mobile stations
43 dB below PEP
Amateur services operating below 30 MHz (including
43 + 10 log (PEP), or 50 dB, whichever is less stringent
those using SSB)
Services operating below 30 MHz, except space,
43 + 10 log (X), or 60 dBc, whichever is less stringent,
radiodetermination, broadcast, those using SSB from
where X = PEP for SSB modulation, and X = P for other
mobile stations, and amateur
modulation
Low-power device radio equipment
56 + 10 log (P), or 40 dBc, whichever is less stringent
Emergency transmitters
No limit
45
APPENDIX B :Table of transmitter frequency tolerances
Frequency bands and categories of stations
Tolerances applicable
to transmitters
Band:
9 kHz to 535 kHz
1 Fixed stations:
2
3
– 9 kHz to 50 kHz
100
– 50 kHz to 535 kHz
50
Land stations:
a) Coast stations
100
b) Aeronautical stations
100
Mobile stations:
a) Ship stations
200
b) Ship’s emergency transmitters
500
c) Survival craft stations
500
d) Aircraft stations
100
4
Radiodetermination stations
100
5
Broadcasting stations
10 Hz
Band:
535 kHz to 1 606.5 kHz
stations
Broadcasting
10 Hz
(WRC-03)
Band: 1 606.5 kHz to 4 000 kHz
1
2
Fixed stations:
– power 200 W or less
100
– power above 200 W
50
Land stations:
– power 200 W or less
100
– power above 200 W
50
46
3
4
5
Mobile stations:
a) Ship stations
40 Hz
b) Survival craft stations
100
c) Emergency position-indicating radio beacons
100
d) Aircraft stations
100
e) Land mobile stations
50
Radiodetermination stations:
– power 200 W or less
20
– power above 200 W
10
Broadcasting stations
10 Hz
Band: 4 MHz to 29.7 MHz
1
Fixed stations:
a) Single-sideband and independent-sideband emissions:
– power 500 W or less
– power above 500 W
b) Class F1B emissions
50 Hz
20 Hz
10 Hz
c) Other classes of emission:
– power 500 W or less
– power above 500 W
2
20
10
Land stations:
a) Coast stations
20 Hz
b) Aeronautical stations:
– power 500 W or less
100
– power above 500 W
50
c) Base stations
20
47
3
Mobile stations:
a) Ship stations:
1) Class A1A emissions
2) Emissions other than Class A1A
10
50 Hz
b) Survival craft stations
50
c) Aircraft stations
100
d) Land mobile stations
40
4
Broadcasting stations
10 Hz
5
Space stations
20
6
Earth stations
20
Band: 29.7 MHz to 100 MHz
1
Fixed stations:
– power 50 W or less
– power above 50 W
30
20
2
Land stations
20
3
Mobile stations
20
4
Radiodetermination stations
50
5
Broadcasting stations (other than television)
2 000 Hz
6
Broadcasting stations (television sound and vision)
500 Hz
7
Space stations
20
8
Earth stations
20
48
Band:
1
100 MHz to 470 MHz
Fixed stations:
– power 50 W or less
– power above 50 W
2
20
10
Land stations:
a) Coast stations
10
b) Aeronautical stations
20
c) Base stations:
– in the band 100-235 MHz
3
15
– in the band 235-401 MHz
7
– in the band 401-470 MHz
5
Mobile stations:
a) Ship stations and survival craft stations:
– in the band 156-174 MHz
10
– outside the band 156-174 MHz
50
b) Aircraft stations
30
c) Land mobile stations:
– in the band 100-235 MHz
15
– in the band 235-401 MHz
7
– in the band 401-470 MHz
5
4
Radiodetermination stations
50
5
Broadcasting stations (other than television)
2 000 Hz
6
Broadcasting stations (television sound and vision)
500 Hz
7
Space stations
8
Earth stations
20
20
49
Band:
1
470 MHz to 2 450 MHz
Fixed stations:
– power 100 W or less
– power above 100 W
100
50
2
Land stations
20
3
Mobile stations
20
4
Radiodetermination stations
500
5
Broadcasting stations (other than television)
100
6
Broadcasting stations (television sound and vision)
in the band 470 MHz to 960 MHz
500 Hz
7
Space stations
20
8
Earth stations
20
Band: 2 450 MHz to 10 500 MHz
1
Fixed stations:
– power 100 W or less
– power above 100 W
200
50
2
Land stations
100
3
Mobile stations
100
4
Radiodetermination stations
1 250
5
Space stations
50
6
Earth stations
50
50
Band:
10.5 GHz to 40 GHz
1
Fixed station
300
2
Radiodetermination stations
5 000
3
Broadcasting stations
100
51