Ministerio de Tecnologías de la Información y las Comunicaciones. Republic of Colombia. National Radio Spectrum Management Handbook - PDF

Ministerio de Tecnologías de la Información y las Comunicaciones Republic of Colombia National Radio Spectrum Management Handbook Title II - Radio Spectrum Engineering May 2010 Title II Radio Spectrum

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Ministerio de Tecnologías de la Información y las Comunicaciones Republic of Colombia National Radio Spectrum Management Handbook Title II - Radio Spectrum Engineering May 2010 Title II Radio Spectrum Engineering May Title II Radio Spectrum Engineering May TABLE OF CONTENTS Page No. PART 1. FUNDAMENTALS... 9 Chapter 1. Spectrum Engineering Aids Propagation modelling, selecting the right model Radio wave propagation modes Propagation specifics of various frequency bands Overview of path loss models Practical examples of path loss models Topographic data Coordinate systems Geodetic datum and database compatibility Horizontal spacing in a macroscopic database General principles of data storage for terrain heights Representation of terrain height data Urban area topographic databases Macroscopic ground cover information Special purpose ground cover information Population data Geographic Information System Practical examples Geophysical data maps Noise level evaluation External radio noise Thermal noise of receiver Metrics of efficient spectrum use Units and their conversion Automated Spectrum Management System Chapter 2. Analysis of interference General principles Co-channel interference Interference in adjacent channel Desensitization (blocking) Intermodulation Other types of interference Spurious emissions Harmonics Parasitic emissions Cross-modulation Extent and probability of interference Chapter 3. Sharing of frequency bands Technical principles of frequency band sharing Frequency separation Spatial separation Time separation Signal separation Role of Software Defined Radio/Cognitive Radio Frequency sharing by services... 69 Title II Radio Spectrum Engineering May Sharing between land mobile and broadcasting services Sharing between fixed services and broadcasting services Same service sharing of the band: broadcasting Sharing with radar systems Sharing using spread spectrum techniques Glossary of references on frequency band sharing Chapter 4. Protection ratios General criteria For different services For different bands Chapter 5. Radiation limits CISPR limits EMF human exposure limits Chapter 6. Considerations on site engineering Site sharing General considerations Considerations on antenna isolation Co-siting of MF radio broadcasting antennas Infrastructure sharing PART 2. PRACTICAL APPLICATIONS Chapter 7. Ensuring compatibility of frequency assignments Principles of Frequency-Distance separation Land Mobile Services (Private Mobile Radio) Fixed Services Broadcasting services Background to broadcasting planning AM radio broadcasting FM radio broadcasting in VHF band TV broadcasting in VHF/UHF bands Introduction of digital broadcasting FS/FSS in shared bands Chapter 8. International coordination: triggers and procedures General principles, role of international agreements Land Mobile Services Private Mobile Radio (VHF/UHF) Mobile systems (2G/3G) Fixed Services Point-to-Point Point-to-Multipoint FSS Chapter 9. Band sharing evaluation Statistical modelling of interference potential Sharing between civil and non-civil services Chapter 10. Notification to ITU BR IFIC Terrestrial services Space services Chapter 11. Principles and means of making technology-neutral assignments General principles Technology-neutral assignments in land mobile service bands Title II Radio Spectrum Engineering May Technology-neutral assignments in fixed service bands Unlicensed bands for broadband Wireless Access Systems Chapter 12. Technical aspects of refarming of frequency bands General principles Digital dividend Terms and definitions Bibliography for further reading List of ITU-R reference sources used in this Manual References Title II Radio Spectrum Engineering May INDEX OF TABLES Page No. Table 1: Propagation modes and usages for various frequency bands Table 2: Guide to application of ITU-R radio wave propagation prediction methods Table 3: AM radio station s reference field strength at 1.6 km from antenna Table 4: Representative values of ground conductivity Table 5: MF field strength reduction factors for different frequencies Table 6: Typical required field strength values for MF broadcasting reception Table 7: Choice of coordinate systems for digital mapping Table 8: Categories to be listed in a macroscopic ground cover database Table 9: Additional categories and parameters for database of special structures Table 10: ITU-R digital maps of geophysical parameters Table 11: Methods to facilitate sharing of frequency bands Table 12: TV/FM sound broadcasting service: field strength values to be protected Table 13: Land Mobile service: field strength values to be protected Table 14: Protection ratios for Land Mobile Service from sound broadcast service Table 15: Glossary of references on frequency band sharing Table 16: Relevance of ITU-R recommendations to certain sharing scenarios Table 17: Glossary of references on protection criteria for various services Table 18: Glossary of references on protection criteria as relevant in different bands Table 19: Measured levels of field strength from ISM equipment in various bands Table 20: Parameters of considered PMR systems Table 21: Off-Channel Rejection results for interference between two PMR systems Table 22: Required separation distance between two PMR systems Table 23: Required isolation, L I (db) as function of fading margin N (db) Table 24: Radio frequency channel arrangements for FS links Table 25: Co-ordination distances for frequency assignment to FS links Table 26: Examples of pfd limits for co-ordinated deployment of PMP systems Table 27: Partitioning of MHz band in Colombia Title II Radio Spectrum Engineering May INDEX OF FIGURES Page No. Figure 1: Wave guide propagation mode of radio waves... 9 Figure 2: Ground wave propagation mode of radio waves Figure 3: Sky wave propagation mode of radio waves Figure 4: Space wave propagation mode of radio waves Figure 5: Illustration of radio wave diffraction Figure 6: Example of MF wave propagation over irregular terrain Figure 7: Tropospheric scattering of radio waves Figure 8: Point-to-point communication Figure 9: Irregular-Earth path for defining integral equation of MF propagation model Figure 10: Example of path profile validation for microwave point-to-point link Figure 11: Calculation of reception areas based on terrain information Figure 12: Field strength in urban area (note better propagation along street canyons ) Figure 13: 3-dimensional view of radio stations coverage in mountainous region Figure 14: Example of 3D urban map achievable with 1-5 m resolution building database Figure 15: External radio noise: frequencies 10 khz to 100 MHz Figure 16: External radio noise: frequencies 100 MHz to 100 GHz Figure 17: Illustration of concept of useful/denied space of a radio system Figure 18: Generalised structure of Automated Spectrum Management System Figure 19: Frequency-distance separation curve example Figure 20: Illustration of desensitization (blocking) Figure 21: Interference through harmonics Figure 22: Principle of evaluating minimum separation distance by MCL approach Figure 23: Random sequencing of real-life operational scenarios with Monte-Carlo approach Figure 24: Example of SEAMCAT graphic user interface Figure 25: Further example of SEAMCAT graphic user interface Figure 26: Example of simulating CDMA system interference in SEAMCAT Figure 27: Illustration of channel raster and frequency separation concept Figure 28: Illustration of guard band at the edge of a GSM band Figure 29: Illustration of spatial separation Figure 30: Protection ratio function for FM radio stations planning Figure 31: Illustration of concept of Protection Ratio Figure 32: Illustration of concept of I/N criterion Figure 33: Antenna isolation in horizontal, vertical and slant direction Figure 34: Three types of radio frequency channel arrangements for FS Figure 35: Interference cases in terrestrial FS links Figure 36: Lattice of theoretically planned broadcasting transmitters Figure 37: Frequency assignment and commissioning of broadcasting stations Figure 38: Example of assigning TV channels in theoretical lattice Figure 39: Concept of preferential channels for frequency co-ordination Figure 40: Example of code partitioning for co-ordination of CDMA 3G systems Figure 41: Concept of keyhole coordination area for Fixed Service links Figure 42: Concept of double pfd trigger for co-ordination of PMP systems Figure 43: Flowchart for spectrum sharing evaluation process Figure 44: Scenario of mobile-to-mobile interference Figure 45: Example of simulating mobile-to-mobile scenario Figure 46: Estimating C/I compliance for statistically generated events Figure 47: Flexibility dimensions in radio spectrum management Title II Radio Spectrum Engineering May Figure 48: Mechanisms for transfer of spectrum use rights Figure 49: PLMS deployment options in MHz Figure 50: Example of fragmented partitioning of GSM band for different technologies Figure 51: Deploying GSM and UMTS in sandwich model Figure 52: Two operators blocks deployed in a combined sandwich model Figure 53: Possible network topologies vs. applications within the fixed service bands Figure 54: Base Stations Block Edge Mask for systems in 3.5 GHz band Figure 55: Different levels and degrees of frequency band refarming Figure 56: Refarming as a part of an overall spectrum management cycle Figure 57: European frequency arrangement for digital dividend band MHz Figure 58: Example of BS BEM for a FDD operator in the digital dividend band Title II Radio Spectrum Engineering May PART 1. FUNDAMENTALS Chapter 1. Spectrum Engineering Aids Material in this chapter will describe some fundamental concepts and essential aids to be used as part of spectrum engineering exercises. This include modelling of wave propagation, terrain data considerations, evaluation of thermal and environmental noise, as well as metrics that may be used as means of evaluating efficiency of spectrum use. Separate section is devoted to describe measurement units and their conversions, and final section introduces principles of automated spectrum management system. 1.1 Propagation modelling, selecting the right model All kinds of interaction with radio waves do occur over some distance, be it the primary desirable act of radio communication between two separated terminals or the unwanted interference from one radio transmitter to unintended receiver. Thus evaluation of loss incurred onto radio signal while being in transition between the transmitter (the source of radio waves) and the receiver (the end of radio path) is one of the prime fundamental tasks in any spectrum engineering assessment. This loss is understood in physical terms as reduction of power (amplitude) of travelling radio signal and is called path loss of radio signal. Several path loss models have been developed to describe and evaluate it. The most typical examples of path loss modelling are: evaluating the range of reliable coverage of a radio system and evaluating the impact of interfering signal coming from a certain distance Radio wave propagation modes Before considering the various types of path loss models, it is useful to describe the different radio frequency bands, each having some unique features making them suitable for using in radiocommunications of particular kind. These frequency bands are defined by the physical characteristics of radio waves (especially the wavelength) that determine the behaviour of radio waves in free space (ether), such as how they propagate and how far they propagate. The first of these features is described as the propagation mode [1]. The prime factor that determines which propagation mode radio waves travel is the relationship of wave length to the configuration of Earth surface and ionosphere the upper layer of Earth atmosphere which is ionised by solar radiation and therefore forms a reflective layer encasing the entire planet. A detailed explanation of the different propagation modes is presented hereafter: Wave guide This propagation mode is specific to very low frequency bands (3-30 khz) because their extreme wave length (up to 100 km) is commensurate with the height of the ionosphere layer above Earth surface. Therefore these waves become locked between Earth surface and E-layer of ionosphere and propagate as if they were encased within a waveguide. This is illustrated in Figure 1 below. Ionosphere (E-layer) km = waveguide Earth surface Figure 1: Wave guide propagation mode of radio waves 1 In this chapter only the topics related to radio wave propagation are discussed, and Chapter 2 is providing detailed analysis of the topics related to analysis of interference. Title II Radio Spectrum Engineering May Given such encased propagation, these very low frequency waves can propagate extremely far, up to several thousand kilometres. Also the E-layer of ionosphere is well aiding the propagation due to the fact that it is present throughout the day and night. However the frequency range of 3-30 khz is extremely narrow and is therefore short of informational capacity. On the other hand, emission of radio waves in this range requires extremely large antennas. Due to these reasons the usage of this frequency range is very limited, typically to applications such as communication with submarine fleet or geophysical research. Alternatively, these frequencies could be used for very short range communications, e.g. wireless heart rate monitors, thanks to their feature of easily escaping the human tissues. However in the latter case the waves would not have the sufficient power and scale for entering the global wave guide propagation mode. Ground Wave This propagation mode is characteristic of frequency range 30 khz 3 MHz and is similar to wave guide mode as in this case the radio waves also travel along the surface of the Earth, closely following its curvature. However in this case, due to lesser wave length in this frequency range ( km), the lower, D-layer of the ionosphere becomes dominant and the propagation happens not by the fact of guiding the waves but mostly through their reflections from D-layer as well as semi-conducting Earth surface, see Figure 2. Ionosphere (D-layer) 50 km Earth surface Figure 2: Ground wave propagation mode of radio waves This propagation mode is more widely used including commercial narrow-band applications, such as Long Wave and Medium Wave broadcasting. The propagation range may be up to 1000 km or more. However the composition and height of D-layer fluctuate depending on the time of the day, which affects the range of communications. To improve reflectivity of the Earth surface, usually the vertical polarisation is used for transmitted radio waves, to alleviate the effect of short circuiting of the electric field component. Sky Wave This propagation mode is typical for frequency range 3-30 MHz, although lower frequencies may be also subject to sky wave propagation in certain conditions (for instance at night, when D-layer of ionosphere degrades and the lower frequency bands, normally locked into ground wave propagation by D-layer, are being released into sky ). In the case of sky wave propagation the uppermost F-2 layer of ionosphere ( km above Earth surface) becomes the dominant reflector of radio waves, and they are being bounced from it towards the Earth, see Figure 3. Ionosphere (F2-layer) km Earth surface Area without reception Area of good reception Figure 3: Sky wave propagation mode of radio waves Title II Radio Spectrum Engineering May Given that in this case radio waves have to travel very high up until they reach the reflection point, their reflection arrives to Earth surface at great distance from departing point. Therefore, although sky wave propagation effectively allows round-the-earth communication due to multiple reflection hops, its usefulness is limited to a great extent due to that alternating pattern of areas of good reception (where reflection lands) and areas with no reception, see Figure 3. This reflective pattern also changes during various times of the day, as ionisation of ionosphere changes following the sun cycles. Therefore practical professional use of short wave communications has often rely on using several frequency bands for the same link, depending on the time of the day and year season. The most widely known usage of this propagation mode is for HF (High Frequency, also known as Short Wave) radio broadcasting in the frequency band 3-30 MHz (for more details see section 7.4.2). By virtue of sky wave propagation, broadcasting in this frequency band may easily reach regional and even global level and therefore its planning is governed by special provisions at the ITU level, notably the procedure set out in Article 12 of the Radio Regulations. It foresees two seasons of HF broadcasting: Season A (March-October) and Season B (October-March). In order to make coordination more efficient, administrations and broadcasters often gather in special (regional and worldwide) coordination groups, such as the HFCC High Frequency Co-ordination Conference [129]. However this short wave band is also often used for professional point-to-point long-range communications (military users, governmental links with diplomatic missions around the world) thanks to global scale afforded by sky wave propagation mode. Space Wave When radio signal frequency exceeds 30 MHz (wave length shorter than 10 m), the radio waves tend to travel by direct line and may penetrate the atmosphere and ionosphere layers without much resistance and thus radio waves escape into space, entering space wave propagation mode, see Figure 4. Ionosphere (F-layer) Space wave Ionosphere (E-layer) Ionosphere (D-layer) Ground plane wave Earth surface Figure 4: Space wave propagation mode of radio waves This means that space wave propagation modes could be used for communication with various spacecrafts. Any reflections from space objects are very low therefore use of space wave reflections is limited to some special scientific applications that use very large antennas to achieve very high directivity and gain. Diffraction This propagation mode happens due to effect of radio waves bending around the edges of obstacles in their path, sometimes referred to as knife-edge diffraction, see Figure 5. This complementary effect is extremely helpful as it allows communications in the absence of line-of-sight. However this effect is not universally present but depends on the required angle of the bend, size of the obstacle and its relation to the wave length. A general principle is that the lower is the frequency of radio waves (i.e. the larger their wave length), the Title II Radio Spectrum Engineering May larger obstacles they could come over, such as bigger hills being surmounted by the waves of upper HF (such as 27 MHz Citizens Band radios) or lower VHF frequency ranges. Still even at higher frequencies of UHF range (300 MHz 3 GHz) the diffraction is present at moderate angles and is, for instance, very helpful to ensure better coverage for cellular systems in urban areas, where UHF frequency signals bend over buildings to achieve coverage in the underlying streets (note however that in such cases even though the achievable bend angle may not be high, the coverage is further helped by reflections from further standing buildings, as shown in Figure 5). Mountain ridge: example of knife-edge diffraction Hill Reflection Urban area Diffraction Figure 5: Illustration of radio wave diffraction To get a deeper insight into the effects of diffraction and to learn how to evaluate its impact numerically, please refer to Recommendation ITU-R P.526 [2]. Medium Frequency broadcasting This case is very important for Colombia since a lot of broadcasting coverage in remote areas relies solely on AM radio transmissions in MF. The MF band extends between MHz with broadcasting portions (known in public as Medium Wave radio broadcasting) being lo
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