Training 2

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Training 2

  1. 1. RF Network Design Tai Koon Sun GSM/UMTS RF Engineering - AP Level 31 Tower 2 Petronas Twin To wer, KLCC Kuala Lumpur, Ma laysia Lucent Technologies - Proprietary
  2. 2. Introduction The high level life cycle of the RF network planning process can be summarised as follows :- • To help the operator to identify their RF Comparative • Issuing of search ring design requirement Analysis • Cand. assessment • Optional Site • Site survey, design, Realisation approval • Drive test (optional) • Discuss and agree RF design parameters, RF Design assumptions and requirement objectives with the customer • Frequency plan RF Design • Neighbour list Implementation • RF OMC data • Coverage requirement • Optimisation • Traffic requirement • Various level of design RF Design (ROM to detail RF design)Slide No.2 Lucent Technologies - Proprietary
  3. 3. Comparative Analysis This is an optional step This is intended to :- • Help an existing operator in building/expanding their network • Help a new operator in identifying their RF network requirement, e.g. where their network should be built For the comparative analysis, we would need to :- • Identify all network that are competitors to the customer • Design drive routes that take in the high density traffic areas of interest • Include areas where the customer has no or poor service and the competitors have serviceSlide No.3 Lucent Technologies - Proprietary
  4. 4. Comparative Analysis The result of the analysis should include :- For an existing operator • All problems encountered in the customer’s network • All areas where the customer has no service and a competitor does • Recommendations for solving any coverage and quality problems For a new operator • Strengths and weaknesses in the competitors network • Problem encountered in the competitors networkSlide No.4 Lucent Technologies - Proprietary
  5. 5. RF Network Design Inputs The RF design inputs can be divided into :- • Coverage requirements – Target coverage areas – Service types for the target coverage areas. These should be marked geographically – Coverage area probability – Penetration Loss of buildings and in-cars • Capacity requirements – Erlang per subscriber during the busy hour – Quality of service for the air interface, in terms GoS – Network capacity • Growth plan - Coverage and CapacitySlide No.5 Lucent Technologies - Proprietary
  6. 6. RF Network Design Inputs • Available spectrum and frequency usage restriction, if any • List of available, existing and/or friendly sites that should be included in the RF design • Limitation of the quantity of sites and radios, if any • Quality of Network (C/I values) • Related network features (FH, DTX, etc.)Slide No.6 Lucent Technologies - Proprietary
  7. 7. RF Network Design There are 2 parts to the RF network design to meet the :- • Capacity requirement • Coverage requirement For the RF Coverage Design Digitised CW Drive Databases Customer Testing Requirements RF Propagation Coverage Link Model Design BudgetSlide No.7 Lucent Technologies - Proprietary
  8. 8. CW Drive Testing CW drive test can be used for the following purposes :- • Propagation model tuning • Assessment of the suitability of candidate sites, from both coverage and interference aspect CW drive test process can be broken down to :- • Equipment required • Power setting Test • Drive route planning • BTS antenna selection Preparation • Channel selection • Test site selection Propagation • Transmitter setup • Drive test Test • Receiver setup • Transmitter dismantle Data • Measurement averaging Processing • Report generationSlide No.8 Lucent Technologies - Proprietary
  9. 9. CW Drive Testing - Test Preparation The test equipment required for the CW drive testing :- • Receiver with fast scanner – Example : HP7475A, EXP2000 (LCC) etc. – The receiver scanner rate should conform to the Lee Criteria of 36 to 50 sample per 40 wavelength • CW Transmitter – Example : Gator Transmitter (BVS), LMW Series Transmitter (CHASE), TX-1500 (LCC) etc. • Base Station test antenna – DB806Y (Decibel-GSM900), 7640 (Jaybeam-GSM1800) etc. • Accessories – Including flexible coaxial cable/jumper, Power meter, extended power cord, GPS, compass, altimeterSlide No.9 Lucent Technologies - Proprietary
  10. 10. CW Drive Testing - Test Preparation Base Station Antenna Selection • The selection depends on the purpose of the test • For propagation model tuning, an omni-directional antenna is preferred • For candidate site testing or verification, the choice of antenna depends on the type of BTS site that the test is trying to simulate. – For Omni BTS : – Omni antennas with similar vertical beamwidth – For sectorised BTS – Utilising the same type of antenna is preferred – Omni antenna can also be used, together with the special feature in the post processing software like CMA (LCC) where different antenna pattern can be masked on over the measurement data from an omni antennaSlide No.10 Lucent Technologies - Proprietary
  11. 11. CW Drive Testing - Test Preparation Test Site Selection • For propagation model tuning, the test sites should be selected so that :- – They are distributed within the clutter under study – The height of the test site should be representative or typical for the specific clutter – Preferably not in hilly areas • For candidate site testing/verification, the actual candidate site configuration (height, location) should be used. • For proposed greenfield sites, a “cherry-picker” will be used.Slide No.11 Lucent Technologies - Proprietary
  12. 12. CW Drive Testing - Test Preparation Frequency Channel Selection • The necessary number of channels need to be identified from the channels available – With input from the customer • The channels used should be free from occupation – From the guard bands – Other free channels according to the up-to-date frequency plan • The channels selected will need to be verified by conducting a pre-test drive – It should always precede the actual CW drive test to verify the exact free frequency to be used – It should cover the same route of the actual propagation test – A field strength plot is generated on the collected data to confirm the channel suitabilitySlide No.12 Lucent Technologies - Proprietary
  13. 13. CW Drive Testing - Test Preparation Transmit Power Setting • For propagation model tuning, the maximum transmit power is used • For candidate site testing, the transmit power of the test transmitter is determined using the actual BTS link budget to simulate the coverage • On sites with existing antenna system, it is recommended that the transmit power to be reduced to avoid interference or inter-modulation to other networks. • The amount of reduction is subject to the possibility if separating the test antenna from the existing antennasSlide No.13 Lucent Technologies - Proprietary
  14. 14. CW Drive Testing - Test Preparation Drive Route Determination • The drive route of the data collection is planned prior to the drive test using a detail road map – Eliminate duplicate route to reduce the testing time • For propagation model tuning, each clutter is tested individually and the drive route for each test site is planned to map the clutter under-study for the respective sites. • It is important to collect a statistically significant amount of data, typically a minimum of 300 to 400 data points are required for each clutter category • The data should be evenly distributed with respect to distance from the transmitter • In practice, the actual drive route will be modified according to the latest development which was not shown on the map. The actual drive route taken should be marked on a map for record purposesSlide No.14 Lucent Technologies - Proprietary
  15. 15. CW Drive Testing - Propagation Test Transmitter Equipment Setup • Test antenna location – Free from any nearby obstacle, to ensure free propagation in both horizontal and vertical dimension – For sites with existing antennas, precaution should be taken to avoid possible interference and/or inter-modulation • Transmitter installation • A complete set of 360º photographs of the test location (at the test height) and the antenna setup should be taken for recordSlide No.15 Lucent Technologies - Proprietary
  16. 16. CW Drive Testing - Propagation Test Scanning Receiver Setup - HP 7475A Receiver Example HP 7475A ReceiverSlide No.16 Lucent Technologies - Proprietary
  17. 17. CW Drive Testing - Propagation Test Scanning Receiver Setup • The scanning rate of the receiver should always be set to allow at least 36 sample per 40 wavelength to average out the Rayleigh Fading effect. For example: scanning rate = 100 sample/s test frequency = 1800 MHz therefore, to achieve 36 sample/40 wavelength, the max. speed is = 40 × 0.1667 = 18.52 m / s = 66.67 km / h 36/100 • It is recommended that :- – Beside scanning the test channel, the neighbouring cells is also monitored. This information can be used to check the coverage overlap and potential interference – Check the field strength reading close to the test antenna before starting the test, it should approach the scanning receiver saturationSlide No.17 Lucent Technologies - Proprietary
  18. 18. Measurement Data Processing Data Averaging • This can be done during the drive testing or during the data processing stage, depending on the scanner receiver and the associated post- processing software • The bin size of the distance averaging depends on the size of the human made structure in the test environment Report Generation • For propagation model tuning, the measurement data is exported into the planning tool (e.g. Asset) • Plots can also be generated using the processing tool or using MapInfo • During the export of the measurement data, it is important to take care of the coordinate system used, a conversion is necessary if different coordinate systems are usedSlide No.18 Lucent Technologies - Proprietary
  19. 19. Propagation Model COST 231 - Hata propagation model Lu (dB) = 46.3 + 33.9 log(f) - 13.82 log(Hb) - a(Hm) + [44.9 - 6.55 log(Hb)] log(d) + Cm where a(Hm) = [1.1*log(f) - 0.7]*Hm - [1.56*log(f) -0.8] For medium sized city, suburban centres with moderate tree density Cm = 0 dB For metropolitan centres Cm = 3 dB The propagation model applies with condition :- • Frequency of operation (f) : 1500 - 2000 MHz • Base station height (Hb): 30 - 200 m • Mobile height (Hm) : 1 - 10 m • Distance (d) : 1 - 20 kmSlide No.19 Lucent Technologies - Proprietary
  20. 20. Propagation Model Hata Model Lu (dB) = 69.55 + 26.16 log(f) - 13.82 log(Hb) - a(Hm) + [44.9 - 6.55 log(Hb)] log(d) For medium-small city a(Hm) = [1.1 log(f) -0.7] Hm - [1.56 log(f) -0.8] For large city a(Hm) = 8.29 [log(1.54 Hm)]2 - 1.1 for f <= 200 MHz a(Hm) = 3.2 [log(11.75 Hm)]2 - 4.97 for f >= 400 MHz For Suburban Lsu (dB) = Lu - 2 [log(f/28)]2 - 5.4 For Rural (Quasi-open) Lrqo (dB) = Lu - 4.78 [log(f)]2 + 18.33 log(f) - 35.94 For Rural (Open area) Lrqo (dB) = Lu - 4.78 [log(f)]2 + 18.33 log(f) - 40.94Slide No.20 Lucent Technologies - Proprietary
  21. 21. CW Drive Testing - Propagation Test Drive Test • Initiate a file to record the measurement with an agreed naming convention • Maintain the drive test vehicle speed according to the pre-set scanning rate • Follow the pre-plan drive route as closely as possible • Insert marker wherever necessary during the test to indicate special locations such as perceived hot spot, potential interferer etc. • Monitor the GPS signal and field strength level throughout the test, any extraordinary reading should be inspected before resuming the test Dismantling Equipment • It is recommended to re-confirm the transmit power (as the pre-set value) before dismantling the transmitter setupSlide No.21 Lucent Technologies - Proprietary
  22. 22. Propagation Model Hata Model The propagation model applies with condition :- • Frequency of operation (f) : 150 - 1000 MHz • Base station height (Hb): 30 - 200 m • Mobile height (Hm) : 1 - 10 m • Distance (d) : 1 - 20 kmSlide No.22 Lucent Technologies - Proprietary
  23. 23. Propagation Model Standard Macrocell Model for Asset Lp (dB) = K1 + K2 log(d) + K3 Hm + K4 log(Hm) + K5 log(Heff) + K6 log(Heff) log(d) + K7 Diffraction + Clutter factor where Lp, Diffraction, Clutter factor are in dB d, Hm, Heff are in m • It is based on the Okumura-Hata empirical model, with a number of additional features to enhance its flexibility • Known to be valid for frequencies from 150MHz to 2GHz • Applies in condition :- – Base station height : 30 - 200 m – Mobile height : 1 - 10 m – Distance : 1 - 20 km • An optional second intercept and slope (K1, K2) for the creation of a two- piece model with the slope changing at the specified breakpoint distance.Slide No.23 Lucent Technologies - Proprietary
  24. 24. Link Budget Link Budget Element of a GSM Network BTS Antenna Gain Max. Path Loss Fade Margin LNA (optional) Penetration Loss Feeder Loss MS Antenna Gain, Body and Cable Loss ACE Diversity Loss Gain Mobile Transmit Mobile Receiver Power Sensitivity BTS Transmit BTS Receiver Power SensitivitySlide No.24 Lucent Technologies - Proprietary
  25. 25. Link Budget BTS Transmit Power • Maximum transmit power • GSM900 and 1800 networks use radios with 46dBm maximum transmit power ACE Loss • Includes all diplexers, combiners and connectors. • Depends on the ACE configuration • The ACE configuration depends on the number of TRXs and combiners used No of Network ACE Configuration Downlink ACE TRXs Loss (dB) 1 or 2 GSM900 2 antennas per cell, diplexer 1.0 1 or 2 GSM1800 2 antennas per cell, diplexer 1.2 3 or 4 GSM900 2 antennas per cell, diplexer + hybrid combiner 4.4 3 or 4 GSM1800 2 antennas per cell, diplexer + hybrid combiner 4.4Slide No.25 Lucent Technologies - Proprietary
  26. 26. Link Budget Mobile Receiver Sensitivity • The sensitivity of GSM900 and GSM1800 mobile = -102 dBm • The following should be noted :- – The sensitivity level is not sufficient to achieve RXQUAL of 4 without frequency hopping RXQUAL of 5 with frequency hopping • A mobile receiver that moves at 50km/h averages the fading, but a static one will be under more severe fading influences. Therefore :- – If the quality of a static mobile needs to be considered, then a quality margin of approximately 4 - 5 dB is used – The mobile sensitivity would be -97 or -98 dBmSlide No.26 Lucent Technologies - Proprietary
  27. 27. Link Budget Mobile Transmit Power • GSM900 : Typical mobile class 4 (2W) • GSM1800 : Typical mobile class 1 (1W) Class GSM 900 (Watt/dBm) GSM 1800 (Watt/dBm) 1 - 1 / 30 2 8 / 39 0.25 / 24 3 5 / 37 4 / 36 4 2 / 33 - 5 0.8 / 29 - LNA (Optional) • To improve the performance of the uplink • Should be located close to the antenna to :- – Improve the system noise figure – Compensate the feeder lossesSlide No.27 Lucent Technologies - Proprietary
  28. 28. Mast Head Amplifier Achieves quality impovement and cell expansion by improving receive sensitivity at the antenna The Mast Head Amplifier is installed in the receive path, close to the antenna It compensates for the cable loss between antenna and BTS, for the uplink path, allowing higher BTS transmit powers while retaining path balance. Only effective in uplink-limited cellsSlide No.28 Lucent Technologies - Proprietary
  29. 29. Link Budget Diversity Gain • Two common techniques used :- – Space – Polarisation • Reduce the effect of multipath fading on the uplink • Common value of 3 to 4.5 dB being used BTS Receiver Sensitivity • Depends on the type of propagation environment model used, most commonly used TU50 model • BTS2000 :- – Receiver Sensitivity for GSM900 = -107 dBm – Receiver Sensitivity for GSM1800 = -108 dBmSlide No.29 Lucent Technologies - Proprietary
  30. 30. Link Budget Feeder Loss • Depends on the feeder type and feeder length • The selection of the feeder type would depends on the feeder length, I.e. to try to limit to feeder loss to 2 - 3 dB. BTS Antenna Gain • Antenna gain has a direct relationship to the cell size • The selection of the antenna type depends on :- – The morphology classes of the targeted area and coverage requirements – Zoning and Local authority regulations/limitations • Common antenna types used :- – 65º, 90º, omni-directional antennas with different gainsSlide No.30 Lucent Technologies - Proprietary
  31. 31. Link Budget Slow Fading Margin • To reserve extra signal power to overcome potential slow fading. • Depends on the requirement of coverage probability and the standard deviation of the fading • A design can take into consideration :- – both outdoor and in-building coverage, which utilises a combined standard deviation for indoor and outdoor (Default Lucent value = 9dB) – Only outdoor coverage (Default Lucent value = 7dB) – Pathloss slope used, 45dB/dec (Dense Urban), 42dB/dec (Urban), 38dB/dec (Suburban) and 33dB/dec (Rural) Cell Area Combined (outdoor & Outdoor slow fade margin Coverage indoor) slow fade margin (dB) Probability (dB) (%) DU U SU RU DU U SU RU 85 2 3 3 4 1 1 2 2 90 5 6 6 6 3 3 4 4 95 9 9 9 10 6 6 7 7Slide No.31 Lucent Technologies - Proprietary
  32. 32. Link Budget Penetration Loss • Penetration loss depends on the building structure and material • Penetration loss is included for in-building link budget • Typical value used for Asia-Pacific environment (if country specific information is not available) :- – Dense Urban : 20 dB – Urban : 18 dB – Suburban : 15 dB – Rural : 9 dB Body Loss • Typical value of 2dB body loss is used MS Antenna Gain • A typical mobile antenna gain of 2.2 dBi is usedSlide No.32 Lucent Technologies - Proprietary
  33. 33. Link Budget Link Budget Example (GSM900) UPLINK DOWNLINK MS Transmit Power 33 dBm BTS Transmit Power 46 dBm Cable Loss 0 dB ACE Loss Z MS Antenna Gain 2.2 dBi Feeder Loss 2 dB Body Loss 2 dB LNA Gain 0 dB Penetration Loss W BTS Antenna Gain 18 dBi Slow Fade Margin X Max. Path Loss Y Max. Path Loss Y Slow Fade Margin X BTS Antenna Gain 18 dBi Penetration Loss W LNA Gain 0 dB Body Loss 2 dB Feeder Loss 2 dB MS Antenna Gain 2.2 dBi ACE Loss 0 dB Cable Loss 0 dB Diversity Gain 4 dB Diversity Gain 0 dB BTS Receiver Sensitivity -107 dBm MS Receiver Sensitivity -102 dBmSlide No.33 Lucent Technologies - Proprietary
  34. 34. Antenna Antenna Selection • Gain • Beamwidths in horizontal and vertical radiated planes • VSWR • Frequency range • Nominal impedance • Radiated pattern (beamshape) in horizontal and vertical planes • Downtilt available (electrical, mechanical) • Polarisation • Connector types (DIN, N) • Height, weight, windload and physical dimensionsSlide No.34 Lucent Technologies - Proprietary
  35. 35. Antenna The antenna selection process • Identify system specifications such as polarisation, impedance and bandwidth • Select the azimuth or horizontal plane pattern to obtain the needed coverage • Select the elevation or vertical plane pattern to be as narrow as possible, consistent with practical limitations of size, weight and cost • Check other parameters such as cost, power rating, size, weight, mounting capabilities, wind loading, connector types, aesthetics and reliability to ensure that they meet system requirementsSlide No.35 Lucent Technologies - Proprietary
  36. 36. Antenna System Specification • Impedance and frequency bandwidth is normally associated with the communication system used • The polarisation would depends on if polarisation diversity is used Horizontal Plane Pattern • Three categories for the horizontal plane pattern :- – Omnidirectional – Sectored (directional) – Narrow beam (highly directional) Elevation Plane Pattern • Choosing the antenna with the smallest elevation plane beamwidth will give maximum gain. However, beamwidth and size are inversely related • Electrical down tilt • Null fillingSlide No.36 Lucent Technologies - Proprietary
  37. 37. Antenna Example • 90º vs 60º horizontal beamwidth – Bore sight gain vs performance at sector cross over – Indoor : 90º antenna gives a more circular coverage • Vertical Beamwidth – Wider vertical beamwidth, better RF performance in rolling terrain • Excessive Multipath Environment – Reduce horizontal and vertical beamwidth • Long Bridge over Water – Very high gain antennas with extremely narrow beamwidthSlide No.37 Lucent Technologies - Proprietary
  38. 38. Receive Diversity Diversity schemes provide two or more inputs at the receiver so that the fading phenomena among the inputs are less correlated Types of Receive Antenna Diversity • Space diversity • Polarisation diversity Space Diversity • Two receive antenna separated physically by a distance, d • The separation, d, varies with the antenna height h η= ,η = f( ρ ) d where h = antenna height d = antenna separation distance ρ = correlation coefficient of 2 signals received • For practical limitation, the diversity antenna distance for :- – GSM900 : approximately 3 m – GSM1800 : approximately 1.5 mSlide No.38 Lucent Technologies - Proprietary
  39. 39. Nominal RF Design Link Budget Propagation Coverage Traffic model requirements requirements Maximum path loss Nominal RF Site radius Design • Recalculate the site (coverage) radius using the Typical site • Standard hexagon site number of sites from layout the traffic requirement configuration • Friendly, candidate sites • Repeat the nominal • Transmit Power • Initial site survey inputs RF design • Antenna configuration Coverage site (type, height, azimuth) count • Site type (sector, omni) Traffic site Traffic > Cov. Traffic Nominal site requirements count Cov. > Traffic countSlide No.39 Lucent Technologies - Proprietary
  40. 40. Nominal RF Design Calculation of cell radius • A typical cell radius is calculated for each clutter environment • This cell radius is used as a guide for the site distance in the respective clutter environment • The actual site distance could varies due to local terrain Inputs for the cell radius calculation :- • Maximum pathloss (from the link budget) • Typical site configuration (for each clutter environment) • Propagation model Example (GSM1800) :- • Maximum Pathloss = 138 dB • Standard COST231 model • Typical Site Configuration (Urban) • Mobile Height = 1.5 m – Antenna Height = 30 m – EiRP = 56 dBmSlide No.40 Lucent Technologies - Proprietary
  41. 41. Nominal RF Design COST231-Hata model (Urban) Lu (dB) = 46.3 + 33.9 log(f) - 13.82 log(Hb) - a(Hm) + [44.9 - 6.55 log(Hb)] log(d) a(Hm) = 0.0432 Rearranging the equation and substituting the value given :- 35.22 Log(d) = 136.24 - 0.0432 - 138 d = 0.889 km • The cell radius is calculated without using any terrain/clutter information – A margin is taken to take into consideration of diffraction and implementation margin – A clutter offset (for each clutter type) can be applied • In a standard 3 sector hexagon site configuration, the relationship between the cell radius and site distance is :- Site Distance = 1.5 x Maximum Cell RadiusSlide No.41 Lucent Technologies - Proprietary
  42. 42. Nominal RF Design There are different level of nominal RF design :- • Only using the cell radius/site distance calculated and placing ideal hexagon cell layout • Using the combination of the calculated cell radius and the existing/friendly sites from the customerSlide No.42 Lucent Technologies - Proprietary
  43. 43. Nominal RF Design The site distance also depends on the required capacity • In most mobile network, the traffic density is highest within the CBD area and major routes/intersections • The cell radius would need to be reduce in this area to meet the traffic requirements If the total sites for the traffic requirement is more than the sites required for coverage, the nominal RF design is repeated using the number of sites from the traffic requirement • Recalculating the cell radius for the high traffic density areas • The calculation steps are :- – Calculate the area to be covered per site – Calculate the maximum cell radius – Calculate the site distanceSlide No.43 Lucent Technologies - Proprietary
  44. 44. Site Realisation Lucent Objective Lucent Add sites to survey schedule Lucent Link objective to sites Cust / Lucent Site Survey Site Identification process Prioritise Lucent RF Design objective No Other sites Lucent Yes Planning High priority No Site Package available for meeting objectives with objective ? forwarded to Cust linked sites Cust / Lucent Cust / Lucent Accepted Yes Implementation Rejected Prioritise sitesSlide No.44 Lucent Technologies - Proprietary
  45. 45. Site Realisation All parties Produce Release of Suitable Y Candidates Y Arranged Y Caravan agreed at Final RF Search Ring Candidates? Approved? Caravan Design N N N Problem Next identifying candidate Caravan next candidate candidate N Exhausted candidates N Exhausted Y candidates Discuss Driveby, RF alternative with suggest possible customer alternative Y N Candidate Y approved? N N Issue design Cell split Additional sites change required required Y YSlide No.45 Lucent Technologies - Proprietary
  46. 46. Site Realisation Site Search Ring Release Search Ring Form Site Id : 1001 Site Name : Hillborough Date (DD/MM/YYYY) : 01/06/2000 • Site ID Design Engineer : John D Form.Revision.No. : 1.0 Phase : 1 Project ID : Dummy • Site Name • Latitude/Longitude Degree Minutes Seconds S/E Latitude : 36 55 18.28 S Longitude: 174 45 40.80 E Ground Elevation (mts): 60 Morphology : High Rise Buiding Urban • Project name Dense-Urban Industrial Suburban Rural Other X • Issue Number and date • Ground height Preliminary Configuration : Sector 1 Sector 2 Sector 3 0 0 0 Antenna Orientation 0 120 240 Antenna Type Kathrein Kathrein Kathrein Recommended Antenna Height 15 739-495 739-495 739-495 • Clutter environment Search Area : Search Radius : As marked on attached map. 150m • Preliminary configuration Objective : Hillsborough 0 0 0 0 0 0 0 • Number of sector • Azimuth Attachments: 1) Propagation Plot (GRAND/CE4/____________) : No • Antenna type 2) Copy of Map showing Theoretical Site and Search Area ? Yes 3) Auckland Street Directory Map No.: 48/AW31 4) Terrain and Clutter Plot (GRAND / CE4 / ___________) : No 5) MW Transmission connectivity diagram 6) Any other Document (specify) • Antenna height Remarks: • Search ring radius • Search ring objective RELEASE APPROVAL PROCESS RF Project Office RF Manager : Project / Implementation Manager : • Attachment Name : Name : Date : Date : Proceed : Yes No Release Date : • Location map Release To :Slide No.46 Response Due Date : DCC CN : • Approvals Lucent Technologies - Proprietary
  47. 47. Site Realisation Candidate Assessment Report • Includes all suitable candidates for the search ring • For each candidates :- – Location (latitude/longitude) – Location map showing the relative location of the candidates and also the search ring – Candidate information (height, owner etc) – Photographs (360º set, rooftop, access, building) – Possible antenna mounting position – Possible base station equipment location – Information for any existing antennas – Planning reports/comments (restrictions, possibilities of approval etc.)Slide No.47 Lucent Technologies - Proprietary
  48. 48. Site Realisation RF and Transmission Final Configuration Form Site ID: Final RF Configuration Form RF Engineer: Transmission Eng: Site Acquisition: Date: Contact Address/Telephone Version: • Base Station configuration Site Address – Azimuth – Antenna height Structure Type Building Monopole Existing Tower Structure Height RF Details Alpha Beta Gamma Omni – Antenna type – Down tilt Orientation (deg/TN) Antenna Height(m) Antenna Type Downtilt (E/M) Antenna Location – Antenna location Feeder Type Feeder Length (m) BTS Type – Feeder type and length Max.Tx Power (dBm) Initial RT Configuration Future RT Configuration – BTS type Transmission Details LOS 1 LOS 2 LOS 3 – Transmit power – Far End Site ID Bearing (deg/MN) Height (m) Transceiver configuration Antenna Model Antenna Size (ft/mm) Antenna Location Capacity (E1/T1) Freq. Band (Ghz) Additional Comments Signed RF Engineer Tx EngineerSlide No.48 DCC C/N Lucent Technologies - Proprietary
  49. 49. Site Realisation The suitability of a candidate site is determine based on the coverage that the candidate will provide (against the design coverage) and the interference that the candidate site will cause • Antenna selection – Type : omni, directional (options of various beamwidth) – Type : Cross-polarised, vertical polarised – Downtilt : fixed, variable – Gain (low, medium, high) • Antenna installation – Clear of any local clutters, obstructions – d ≥ 2D2/λ, where D is the maximum antenna dimension – Obstacles within the surrounding region can dramatically distort RF radiation pattern – Position antenna such that at least the main lobe is un-obstructed – 1:3 rule of thumb for antenna height vs distance to roof top parapetSlide No.49 Lucent Technologies - Proprietary
  50. 50. Site Realisation • Antenna installation – Omni-directional antenna – Normally mounted at the highest point possible – If it is side mounted, the antenna pattern will be distorted due to tower RF wave reflection and shadowing – Directional antenna – For the new cross-polarised antenna, all the 3 antennas can be mounted on a single pole – Wall Mounting – Ideal perpendicular to wall surface – Avoid metal building structural objects – Corner Mounting – Maximum 15º from perpendicular direction to avoid distortionSlide No.50 Lucent Technologies - Proprietary
  51. 51. Site Realisation • Collocating with other antennas – Spurious emission – Cause rx desensitization (noise floor increase) – Level should be 10dB below thermal noise floor – IMP3 – Cause by rx LNA non-linearity – IMP3 level 10dB below thermal noise floor – Receiver overload – Total received power drive amplifier into non-linear gain region – Total rx power 5dB below 1dB compression point of rx amplifier – Use vertical separation if possible (provide better decoupling)Slide No.51 Lucent Technologies - Proprietary
  52. 52. Site Realisation • Antenna downtilt θ = arctan(h/2R) + BWv/2 (equation 1) θ = 180 - 2* arctan(R/h) (equation 2) where R = cell radius h = antenna height BWv = antenna vertical beamwidth Arctan(h/2R) desired Interfering R R Arctan(h/R) desired RSlide No.52 Lucent Technologies - Proprietary
  53. 53. Site Realisation • Antenna downtilt reduces the interference to neighbouring cells and enhance the weak spots in the cell • Equation 1 is used to control extreme interference, reduces the interference at the neighbouring cell (d=2R) by 3dB • Equation 2 is used to improve interference, preserving the coverage at the edge of the cell (d=R) • RF feeder run :- – Proposed route – Feeder length – Feeder typeSlide No.53 Lucent Technologies - Proprietary
  54. 54. Traffic Engineering Spectrum Reuse factor Available Traffic Requirement Maximum number of TRX per cell Channel No of TCH Subscriber Traffic offered loading available supportedSlide No.54 Lucent Technologies - Proprietary
  55. 55. Traffic Engineering Traffic Requirement The Erlang per subscriber (during busy hour) is given by :- BHCA × Average call holding time( s ) Erlang / sub = 3600 where BHCA = Busy hour call attempt Average call holding time = Duration of time (s) for an average call Grade of Service (GoS) • GoS is expressed as the percentage of call attempts that are blocked during peak traffic • Most cellular systems are designed to a blocking rate of 1% to 5% during busy hour • Outside busy hour, the blocking rate is much lowerSlide No.55 Lucent Technologies - Proprietary
  56. 56. Traffic Engineering Frequency Reuse • In designing a frequency reuse plan, it is necessary to develop a regular pattern on which to assign frequencies • The hexagon is chosen because it most closely approximated the coverage produced by an omni or sector site • Common reuse factor : 4/12, 7/21Slide No.56 Lucent Technologies - Proprietary
  57. 57. Traffic Engineering Distance to Cell Radius and C/I • The reuse cluster size, N and the D/R ratio are related by :- D = 3N R where D is the distance separation between cell centers and R is the cell radius • As N decreases, the D/R ratio becomes smaller and the C/I ratio goes down, interference increases • As the number of sector increases, the number of potential interferers decreases. For example, using a 3 sector configuration reduces the number of first tier interferers from 6 to 2 • In GSM conventional frequency planning, the 4/12 reuse pattern is typical. Using the inverse 3.5 exponent law, a mean C/I ratio of ~18dB would be found at the edge of the cell • Advance frequency planning techniques further reduces the reuse factorSlide No.57 Lucent Technologies - Proprietary
  58. 58. Traffic Engineering Example :- • Available spectrum = 10 MHz – Available channels : 48 channels Design 1 • Proposed Reuse factor = 4/12 – Channels required per TRX layer : 12 – Number of TRX : 4 Design 2 • Proposed reuse factor for BCCH = 4/12 • Proposed reuse factor for remaining TRX = 3/9 • Number of channels for BCCH layer = 12 • Remaining channels = 36 • Number of channels for non-BCCH layer = 9 • Number of non-BCCH layers = 4 • Total number of TRX = 5Slide No.58 Lucent Technologies - Proprietary
  59. 59. Traffic Engineering Channel Loading • As the number of TRX increases, the control channels required increases accordingly • The following channel loading is used for conventional GSM network • For services such as cell broadcast, additional control channels might be required Number of TRX Control Channels Number of TCH 1 Combined BCCH/SDCCH 7 2 Combined BCCH/SDCCH 15 3 1 BCCH, 1 SDCCH 22 4 1 BCCH, 1 SDCCH 30 5 1 BCCH, 2 SDCCH 37 6 1 BCCH, 2 SDCCH 45 7 1 BCCH, 3 SDCCH 52 8 1 BCCH, 3 SDCCH 60Slide No.59 Lucent Technologies - Proprietary
  60. 60. Traffic Engineering After determining the number of TCH available and the traffic requirements, the traffic offered is calculated using the Erlang B table • For example, for a 2% GoS and 3 TRX configuration, the traffic offered is 14.9 Erlang • If the traffic per subscriber is 35mE/subscriber, then the total subscribers supported per sector = 425 For a uniform traffic distribution network, the number of sites required for the traffic requirement is :- Total subscribers Total sites = Subscriber supported per siteSlide No.60 Lucent Technologies - Proprietary
  61. 61. Traffic Engineering Erlang B Table N 1% 1.20% 1.50% 2% 3% 5% 7% 10% 15% 20% 30% 40% 50% 1 0.01 0.01 0.02 0.02 0.03 0.05 0.1 0.11 0.18 0.25 0.43 0.67 1 2 0.15 0.17 0.19 0.22 0.28 0.38 0.5 0.6 0.8 1 1.45 2 2.73 3 0.46 0.49 0.54 0.6 0.72 0.9 1.1 1.27 1.6 1.93 2.63 3.48 4.59 4 0.87 0.92 0.99 1.09 1.26 1.52 1.8 2.05 2.5 2.95 3.89 5.02 6.5 5 1.36 1.43 1.52 1.66 1.88 2.22 2.5 2.88 3.45 4.01 5.19 6.6 8.44 6 1.91 2 2.11 2.28 2.54 2.96 3.3 3.76 4.44 5.11 6.51 8.19 10.4 7 2.5 2.6 2.74 2.94 3.25 3.74 4.1 4.67 5.46 6.23 7.86 9.8 12.4 8 3.13 3.25 3.4 3.63 3.99 4.54 5 5.6 6.5 7.37 9.21 11.4 14.3 9 3.78 3.92 4.09 4.34 4.75 5.37 5.9 6.55 7.55 8.52 10.6 13 16.3 10 4.46 4.61 4.81 5.08 5.53 6.22 6.8 7.51 8.62 9.68 12 14.7 18.3 11 5.16 5.32 5.54 5.84 6.33 7.08 7.7 8.49 9.69 10.9 13.3 16.3 20.3 12 5.88 6.05 6.29 6.61 7.14 7.95 8.6 9.47 10.8 12 14.7 18 22.2 13 6.61 6.8 7.05 7.4 7.97 8.83 9.5 10.5 11.9 13.2 16.1 19.6 24.2 14 7.35 7.56 7.82 8.2 8.8 9.73 10.5 11.5 13 14.4 17.5 21.2 26.2 15 8.11 8.33 8.61 9.01 9.65 10.6 11.4 12.5 14.1 15.6 18.9 22.9 28.2 16 8.88 9.11 9.41 9.83 10.5 11.5 12.4 13.5 15.2 16.8 20.3 24.5 30.2 17 9.65 9.89 10.2 10.7 11.4 12.5 13.4 14.5 16.3 18 21.7 26.2 32.2 18 10.4 10.7 11 11.5 12.2 13.4 14.3 15.5 17.4 19.2 23.1 27.8 34.2 19 11.2 11.5 11.8 12.3 13.1 14.3 15.3 16.6 18.5 20.4 24.5 29.5 36.2 20 12 12.3 12.7 13.2 14.0 15.2 16.3 17.6 19.6 21.6 25.9 31.2 38.2 21 12.8 13.1 13.5 14 14.9 16.2 17.3 18.7 20.8 22.8 27.3 32.8 40.2 22 13.7 14 14.3 14.9 15.8 17.1 18.2 19.7 21.9 24.1 28.7 34.5 42.1 23 14.5 14.8 15.2 15.8 16.7 18.1 19.2 20.7 23 25.3 30.1 36.1 44.1Slide No.61 Lucent Technologies - Proprietary
  62. 62. Traffic Engineering - Example Given Traffic distribution • Supporting up to 10,000 startup sub • GOS : 2% (0.02) • Traffic/subs : 25 mErlang(0.025 Erlang) NORTH (40%) Solutions SOUTH (60%) A = function(GOS, #TCH) - refer Erlang B table B = A x # Sector Radio Network Capacity = B/Erlang per SubSlide No.62 Lucent Technologies - Proprietary
  63. 63. Traffic Engineering - Example BTS Count with Respective TRX Configuration For Traffic Regions Region Clutter BTS No of Radio Network Capacity Configuration BTS Capacity Forecast 1 North Dense 1/1/1 4 Urban Urban 1/1/1 6 4,351 4,000 Suburban 1/1 3 Rural 1 1 2 South Dense 1/1/1 5 Urban Urban 1/1/1 10 5,998 6,000 Suburban 1/1 2 Rural 1 2 Total 33 10,349 10,000Slide No.63 Lucent Technologies - Proprietary
  64. 64. Traffic Engineering If a traffic map is provided, the traffic engineering is done together with the coverage design After the individual sites are located, the estimated number of subscribers in each sector is calculated by :- • Calculating the physical area covered by each sector • Multiply it by the average subscriber density per unit area in that region • The overlap areas between the sectors should be included in each sector because either sector is theoretically capable of serving the area The number of channels required is then determined by :- • Calculating the total Erlangs by multiplying the area covered by the average load generated per subscriber during busy hour • Determine the required number of TCH and then the required number of TRXs • If the number of TRXs required exceeded the number of TRXs supported by the available spectrum, additional sites will be requiredSlide No.64 Lucent Technologies - Proprietary

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