ele5tde final project report-semester 2, 2011

ELE5TDE Telecommunications Design ExerciseFINAL REPORTSemester 2, 2011

Cellular Mobile Radio Telecommunication Network Planningfor

GSM Technology

Department of Electronic EngineeringSchool of Engineering and Mathematical SciencesFaculty of Science, Technology and Engineering

La Trobe UniversityMelbourne Australia

ELE5TDE TELECOMMUNICATIONS DESIGN FINAL REPORTSemester 2, 2011

Department of Electronic EngineeringSchool of Engineering and Mathematical SciencesFaculty of Science, Technology and Engineering

La Trobe UniversityMelbourne Australia

Cellular Mobile Radio Telecommunication Network Planningfor

GSM Technology

Supervised by Mr. Michael Feramez Senior Lecturer Department of Electronic EngineeringSubmitted by Ishita Akhter 16422890 Date of Submission 31 October, 2011

Dedicated to

My respected teachers My beloved family

DeclarationI hereby declare that I have completed a simulation-based exercise on the topic entitled Cellular Mobile Radio Telecommunication Ne twork Planning - GSM Technology as well as prepared this technical report to the Department of Electronic Engineering, La Trobe University, Victoria, Australia, in partial fulfillment of the requirement for the one year degree of Master of Telecommunication Engineering (Coursework), under the unit Telecommunications Design (ELE5TDE). I further assert that this report in question is based on my original exertion having never been produced fully and/or partially elsewhere, for the requirement of absolutely any academic program.

Ishita Akhter 16422890 SMTE Department of EE La Trobe University

AcceptanceThis technical report, presented to the Department of Electronic Engineering, La Trobe University, is submitted in partial fulfillment of the requirement for the degree of Master of Telecommunication Engineering (Coursework), under complete supervision of the undersigned.

Michael Feramez Senior Lecturer Department of EE La Trobe University

Letter of Transmittal31st October, 2011 To The Subject Coordinator ELE5TDE (Telecommunications Design) Department of Electronic Engineering La Trobe University Victoria 3083, Australia Subject: Submission of Project Report Dear Sir, W ith due respect, I would like to state that It is a matter of great pleasure and honour for me to submit my project report on Cellular Mobile Radio Telecommunication Network Planning - GSM Technology, assigned by yourself as the topic of my project for the subject of ELE5TDE (Telecommunications Design). In preparation of this report I have followed and maintained the format and rules of a formal technical project report as instructed by you. This consignment was of great worth and appeal, as it helped me hone my analytical skills abilities and practical knowledge in the field of cellular mobile radio base station network planning and helped me get familiarized with the real-life process of Telecommunication network planning. I would like to convey my heartfelt thanks and appreciation in recognizing your valuable contribution for allowing me to successfully complete my project for the subject ELE5TDE by providing thoughtful selection, guidance and inspiration, despite your busy schedules. Sincerely yours, _______________ Ishita Akhter 16422890

AcknowledgementFirst & foremost of all, I wish to express my heartiest gratitude and total devotion to almighty Allah for blessing me with the ability, strength, patience as well as keeping me active in performing my project related tasks successfully. A special debt is due to Mr. Michael Feramez, Senior Lecturer, Department of Electronic Engineering, La Trobe University, who has been my academic supervisor for the course of ELE5TDE in the semester 2 of 2011. He was kind enough to allocate his valuable time to provide me with his humble guidance, motivating thoughts, ample & applicable directions for the successful preparation of this report. I would especially like to convey my gratitude to my subject tutor, Mr. Mohsin Murtaza, and my fellow classmates for their valuable inputs that helped me advance my project works performed within the scope of this subject. W ithout their motivation, guidance & suggestions, this report would have remained incomplete. And last but not least, I would finish off with extension of appreciation to my family & friends, whose moral support worked as the main driving force contributing to my successful completion of ELE5TDE and also thanks to my friends for motivating me with their tips & suggestions on preparing my project report.

Sincerely Yours,

Ishita Akhter

Telecommunications Design

I

AbstractThis technical report is documented for the purpose of planning, designing and simulating a cellular mobile telecommunication network based on the GSM technology. The project is implemented for a given set of geographic co-ordinates at co-ordinates North-32o 40 00.0 N, East-093o 30 00.0 W, South-32o 30 00.0 N, West-093o 50 00.0 W, representing two hypothetical location blocks. After the network implementation, ample network coverage was induced with 37 BTSs over the selected location blocks and economical approach of frequency allocation was achieved through the frequency reuse process with a cluster size of 4. The co-channel and adjacent channel interferences for these BTSs were minimized to be negligible and their required minimum C/I ratio of at least 20 dB for composite interference was maintained. Investigation and maintenance of existing traffic over the network was performed with a GoS of 3% and a blocking probability of 2.2%. Finally, switching arrangement of the BSCs that control the BTSs, was achieved by installing two MSCs. One MSc is based on each of the two network location blocks, which connects with all the BTSs in their respective areas and maintain interconnection as well as connection with outside networks like PSTN an ISDN, through LoS microwave links. The report initially specifies the technical requirements, proposes the solutions obtained using CelPlanner, and finally proceeds onto discussing the obtained proposals. The report also focuses on the several restrictions encountered during the construction of proposed solutions and the methods on overcoming them. Overall, the report is a documentation based on the research of one individual to provide an outlook on the roll-out of a functional cellular mobile telecommunication network


II

PrefaceThe purpose of this report is to be part of the assessment for ELE5TDE (Telecommunication Design), a thirty (30) credit points project-based unit in the Master of Telecommunication Engineering (Coursework), which is a one-year master course of a total of one hundred and twenty (120) credit points, offered by the Department of Electronic Engineering at La Trobe University, Victoria, Australia. This project in question here is worth 60% of the total marks allocated to ELE5TDE and comprises of relevant tasks in planning design, and simulation of a cellular mobile network. This report outlines and elaborately discusses the project methods, technical requirement specification, data, corresponding outcomes and references for this final project for ELE5TDE.


III

GlossaryGS M MSC BSC BTS MW RBS MS BS SSA TSA RSL RBS Erl C/I An t Ah t Pwr Tlt Azm Erl n Sv Go S LoS C/I PSTN ISDN Global System for Mobile Communications Mobile Switching Centre Base Station Controller Base Station Transceiver Microwave Radio Base Station Mobile Station Base Station Sub-service Areas Total Service Area Received Signal Level Radio Base Station Erlang Carrier to Interference ratio Antenna Antenna height Antenna power Antenna tilt Azimuth angle Erlang Number of servers Grade of Service Line of Sight Carrier-to-interference Public Switched Telephone Network Integrated Services Digital Network


IV

Table of contentsSections Acknowledgement Abstract Preface Glossary Table of contents List of tables List of figures 1. Introduction 1.1. Background of the project 1.2. Purpose of the report 1.3. Scope of the report 1.4. Organization of the report 2. Cellular Planning Process 2.1. Planning approach 2.1.1. General requirements 2.1.2. System parameters 2.1.3. Mobile terminal parameters 2.1.4. Mobile environment parameters 2.1.5. Service class parameters 2.1.6. Base station parameters 2.1.7. Backhaul network parameters 2.1.8. Path loss model parameters 2.1.9. Geographical parameters 2.1.10. Frequency planning parameters 2.1.11. Teletraffic planning parameters 2.2. Planning tool 2.2.1. Databases 2.2.2. Project databases 2.2.3. Propagation analysis 2.2.4. Traffic/load analysis 2.2.5. Predictions 3. Cellular Network Solution 3.1. Network configuration 3.1.1. Base station location 3.1.2. BTS power level 3.1.3. Antenna type 3.1.4. Antenna mounting structure 3.1.5. Antenna orientation 3.1.6. Cell clustering 3.1.7. Frequency channel allocation 3.1.8. Antenna tilting 3.1.9. Cell size modification 3.2. Traffic channeling capacity 3.3. Backhaul network 3.3.1. MSC placement 3.3.2. Antenna type 3.3.3. Antenna mounting 3.3.4. Network link profile Page I II III IV V VII VIII 1 2 3 4 5 6 7 9 10 11 12 15 16 21 25 26 33 35 39 40 41 42 43 44 46 47 49 50 50 50 51 52 53 54 54 55 56 57 57 57 58


V

4. Discussion and critique 4.1. General overview 4.2. Difficulties encountered 4.3. Meeting current and future requirements 4.4. Observations from the project 5. Appendices 5.1. Project specifications 5.2. CelPlanner output 5.2.1. Individual forward class 1 5.2.2. Individual forward class 2 5.2.3. Individual forward class 3 5.2.4. Individual reverse class 1 5.2.5. Individual reverse class 2 5.2.6. Individual reverse class 3 5.2.7. Composite forward class 1 5.2.8. Composite forward class 2 5.2.9. Composite forward class 3 5.2.10. Composite reverse class 1 5.2.11. Composite reverse class 2 5.2.12. Composite reverse class 3 5.2.13. Co-channel interference class 1 5.2.14. Co-channel interference class 2 5.2.15. Co-channel interference class 3 5.2.16. Adjacent channel interference class 1 5.2.17. Adjacent channel interference class 2 5.2.18. Adjacent channel interference class 3 5.2.19. Composite interference class 1 5.2.20. Composite interference class 2 5.2.21. Composite interference class 3 5.2.22. Traffic distribution scenario 5.3. Additional information as required 5.3.1. Best servers class 1 5.3.2. Best servers class 2 5.3.3. Best servers class 3 5.3.4. Bit error rate class 1 5.3.5. Bit error rate class 2 5.3.6. Bit error rate class 3 5.3.7. Handover class 1 5.3.8. Handover class 2 5.3.9. Handover class 3 5.3.10. Number of servers class 1 5.3.11. Number of servers class 2 5.3.12. Number of servers class 3 5.3.13. Service classes Conclusion References

66 67 69 70 71 72 73 107 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 130 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144


VI

List of tablesTable no. 2 .1 Table name Channel numbering table Page no. 33


VII

List of figuresFigure no. 1.1 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 2.11 2.12 2.13 2.14 2.15 2.16 2.17 2.18 2.19 2.20 2.21 2.22 2.23 2.24 2.25 2.26 2.27 2.28 2.29 2.30 2.31 2.32 2.33 2.34 2.35 2.36 2.37 2.38 2.39 2.40 2.41 2.42 3.1 3.2 3.3 Figure name Cellular network architecture System parameters GSM-900 mobile terminal parameters Pedestrian environment parameters In-v ehicle environment parameters In-building environment parameters Service class parameters Base station parameters 7416-11 parameters 7416-11 3D radiation pattern 7416-14 parameters 7416-14 3D radiation pattern Antenna orientation f or 3-sector cell Parameters of a network link Parameters of 1st radio site Parameters of 2nd radio site Network f orward link parameters Network rev erse link parameters HP4-107 parameters HP4-107 3D radiation pattern Lee model parameters Total service area Sub serv ice area Sub serv ice areas/blocks 10 & 11 Topography of SSA blocks 10 & 11 Topography simulation legend Morphology of SSA blocks 10 & 11 Morphology simulation legend Shrev eport area image II (100k) Shrev eport area image III (250k) Cluster of f our base station sites GSM 900 MHz frequency arrangement Traffic grid creation parameters Traffic simulation parameters Teletraffic load allocations Morphology f actors in traffic allocation CelPlanner sof tware window Database directories Project parameters Prediction parameters f or Lee model Traffic distribution Prediction configuration parameters Prediction threshold levels GSM 900 network arrangement BTS area locations 1st Antenna orientation for 3-sector cell Page no. 2 10 11 12 13 14 15 16 16 17 17 18 19 20 20 21 21 22 23 24 24 25 26 28 28 29 29 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 49 51


VIII

3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 5.1. 5.2. 5.3. 5.4. 5.5. 5.6. 5.7. 5.8. 5.9. 5.10. 5.11. 5.12. 5.13. 5.14. 5.15. 5.16. 5.17. 5.18. 5.19. 5.20. 5.21. 5.22. 5.23. 5.24. 5.25. 5.26. 5.27. 5.28. 5.29. 5.30. 5.31.

2nd Antenna orientation f or 3-sector cell 3rd Antenna orientation for 3-sector cell 1st Antenna orientation for 2-sector cell 2nd Antenna orientation f or 2-sector cell Frequency channel allocation in a BTS Calculation radius f or all BTS sites Traffic channel suggestions Backhaul network arrangement Fresnel zone obstruction MSC1 MSC2 link prof ile MSC1 MSC2 link prof ile parameters MSC1 BTS19 link profile MSC1 BTS19 link profile parameters MSC1 BTS11 link profile MSC1 BTS11 link profile parameters Class 1 individual f orward prediction of the central BTS site (BTS2C) Legends f or class1 individual forward prediction Class 2 individual f orward prediction of the central BTS site (BTS2C) Legends f or class 2 individual f orward prediction Class 3 individual f orward prediction of the central BTS site (BTS2C) Legends f or class 3 individual f orward prediction Class 1 individual reverse prediction of the central BTS site (BTS2C) Legends f or class 1 individual reverse prediction Class 2 individual reverse prediction of the central BTS site (BTS2C) Legends f or class 2 individual reverse prediction Class 3 individual reverse prediction of the central BTS site (BTS2C) Legends f or class 3 individual reverse prediction Class 1 composite f orward prediction Legends f or class 1 composite f orward prediction Class 2 composite f orward prediction Legends f or class 2 composite f orward prediction Class 3 composite f orward prediction Legends f or class 3 composite f orward prediction Class 1 composite reverse prediction Legends f or class 1 composite reverse prediction Class 2 composite reverse prediction Legends f or class 2 composite reverse prediction Class 3 composite reverse prediction Legends f or class 3 composite reverse prediction Class 1 co-channel interf erence prediction Legends f or class 2 co-channel interf erence Class 2 co-channel interf erence prediction Legends f or class 2 co-channel interf erence Class 3 co-channel interf erence prediction Legends f or class 3 co-channel interf erence Class 1 adjacent channel interf erence predictionTelecommunications Design

nd

51 51 52 52 53 54 55 56 58 60 61 62 63 64 65 107 107 108 108 109 109 110 110 111 111 112 112 113 113 114 114 115 115 116 116 117 117 118 118 119 119 120 120 121 121 122 IX

5.32. 5.33. 5.34. 5.35. 5.36. 5.37. 5.38. 5.39. 5.40. 5.41. 5.42. 5.43. 5.44. 5.45. 5.46. 5.47. 5.48. 5.49. 5.50. 5.51. 5.52. 5.53. 5.54. 5.55. 5.56. 5.57. 5.58. 5.59. 5.60. 5.61. 5.62. 5.63. 5.64. 5.65. 5.66. 5.67. 5.68. 5.69. 5.70. 5.71.

Legends f or class 2 adjacent channel interf erence Class 2 adjacent channel interference prediction Legends f or class 2 adjacent channel interf erence Class 3 adjacent channel interf erence prediction Legends f or class 3 adjacent channel interf erence Class 1 composite channel interf erence prediction Legends f or class 2 composite interf erence Class 2 composite interf erence prediction Legends f or class 2 composite interf erence Class 3 composite interf erence prediction Legends f or class 3 composite interf erence Traffic distribution scenario prediction based on topography Traffic distribution scenario prediction based on morphology Legends f or traffic distribution scenario prediction Class 1 best serv ers prediction Legends f or class 1 best serv ers prediction Class 2 best serv ers prediction Legends f or class 2 best serv ers prediction Class 3 best serv ers prediction Legends f or class 3 best serv ers prediction Class 1 bit error rate prediction Legends f or class 1 bit error rate prediction Class 2 bit error rate prediction Legends f or class 2 bit error rate prediction Class 3 bit error rate prediction Legends f or class 3 bit error rate prediction Class 1 handov er prediction Legends f or class 1 handov er prediction Class 2 handov er prediction Legends f or class 2 handov er prediction Class 3 handov er prediction Legends f or class 3 handov er prediction Class 1 number of serv ers prediction Legends f or class 1 number of serv ers prediction Class 2 number of serv ers prediction Legends f or class 2 number of serv ers prediction Class 3 number of serv ers prediction Legends f or class 3 number of serv ers prediction Service classes prediction Legends f or service classes prediction

122 123 123 124 124 125 125 126 126 127 127 128 128 129 130 130 131 131 132 132 133 133 134 134 135 135 136 136 137 137 138 138 139 139 140 140 141 141 142 142


X

1. Introduction


1

1.1 Background of the projectGSM (Global System for Mobile communications) is communication technology that is an open and uses digital cellular technology mobile voice transmission and data services. GSM operates in the 900MHz and 1.8GHz bands in Europe and the 1.9GHz and 850MHz bands in the US. The 850MHz band is also used for GSM and 3G in Australia, Canada and many South American countries [1]. The cellular network in GSM consists of the base station (BTS), the mobile station (MS) and the interface between them for correspondence, as shown below

Figure 1.1: Cellular network architecture

The base station uses a radio connection with the mobile station, for communicating within a certain coverage area, maintaining call quality standards with sufficient capacity and coverage. Therefore, planning such a network is much essential in GSM system [2]. GSM cellular network planning involves requirements likeCost of construction, capacity of constructed network, its coverage ability and location, quality of GSM services provided through the network, Grade of Service (GoS), future expansion and development of the network etc. There are three different types of planning involved, these can beswitching network planning, cellular transmission network planning and radio network planning. The aim of this project is to plan a whole network, design it, and then simulate it to obtain prediction about all related parameters. USA.Telecommunications Design

All these tasks are performed through the

CelPlanner software, developed and distributed by CelPlan Technologies Inc. in Virginia

2

1.2 Purpose of the reportThe formulation of this report is based on the cellular mobile radio telecommunication network planning, as it is 40% of the total marks in the course Telecommunications Design (ELE5TDE), with the whole subject of 30 (Thirty) credit points being 25% of the whole course load of 120 (One hundred and twenty) credit points for the course Master of Telecommunication Engineering, under the Department of Electronic Engineering at La Trobe University, Victoria, Australia. Therefore, the purpose of preparing this report is to partially fulfill the requirement of completing the course of Master of Telecommunication Engineering.


3

1.3 Scope of the reportW ithin the scope of this project, certain essential tasks are performed to ensure the completeness, integrity and clarity of the report. These would includeProject requirement analysis, conceptual design and planning, function allocation, modeling and simulation, performance analysis, appropriate optimization, design documentation etc. For requirement analysis, all associated required parameters mentioned in the project specification are examined, studied and identified. Once the requirements of the project are recognized, the basic design and planning is carried out within the software by constructing a network. Then required function parameters are allocated for all network elements and the model is completed and tested through simulation. After the simulation outcomes are obtained, they are processed and analyzed for underlying performance issues and then optimized accordingly to ensure more efficient operation of the proposed network. W hen all these tasks are accomplished, the corresponding findings are documented following a technical report format. The project mainly deals with primary issues such as Radio Frequency (RF) Coverage, Telecommunication traffic (Teletraffic), and Quality of service, regarding cellular network planning and designing. It also highlights the economic aspects of the cellular mobile network planning while maintaining the desired quality of service (QoS) requirements. Considering all these, the following issues were investigated and the corresponding outcomes were documentedIndividual forward link (BS to MS), individual reverse link (MS to BS), composite forward coverage, co-channel interference, adjacent channel interference, composite interference, best server, handover, bit error rates, service classes, traffic allocation, backhaul network etc. Since the project is solely based on software simulation, deviations from real life cellular network planning are expected. This is due to the fact that many parameters and corresponding observations for telecommunication networks are influenced by external factors like environment, finance, workforce, instrument performance etc. However, for real life cellular network planning scenarios, this project would certainly be an appropriate guideline to follow.


4

1.4 Organization of the reportThe report is categorized into 5 main chapters with additional formal elements attached. The first chapter acts as an introduction to the report, focusing on topics such as background, purpose, scope and organization of the report. The background of the project briefs its main topics, while the purpose and scope state the formal requirement and the potential/limitations of the project respectively and finally, the organization parts acts as a content summary. The second chapter termed as cellular planning process, describes the projects network planning approach for the simulation and the software tool used to obtain the simulation results. The planning approach part consists of corresponding conditions e.g. general requirements, system requirements, mobile terminal requirements, mobile environment requirements, base station requirements, backhaul network requirements, path loss model requirements, geographical requirements, frequency planning requirements, teletraffic capacity planning requirements etc. The third chapter entitled cellular network solution includes the proposed solutions obtained through simulations in CelPlanner. This chapter emphasizes on network configuration, traffic channeling capacity and backhaul network solutions within the constraints mentioned in chapter 2 of this report. The fourth chapter which is called discussion and critique establishes the proposed solution through discussion and suggests utilizing of limitations through alternate solutions. This part is based on general overview, observations, limitations, meeting requirements etc. The idea behind this section is to observe and comment on outcomes of the project and discuss about overcoming constraints and further possibilities of future developments of the network plan in question. The fifth and final chapter is the appendices section that states about project specification, CelPlanner output and all other required additional information.


5

2. Cellular planning process


6

2.1 Planning ApproachThe network planning approach for this project is based on the project specifications of this subject, related to GSM network planning, such asTechnical requirements, path loss model, geographical data, frequency planning, teletraffic capacity planning etc. Once all these specifications are carefully studied and analyzed, the network was planned and created for GSM 900 system with multiple BTS sites, frequency clustering of 4, situated in blocks 10 and 11. The geographical coordinates for these chosen blocks are located at North-32o 40 00.0 N, East-093o 30 00.0 W , South-32o 30 00.0 N, W est-093o 50 00.0 W , for the total service area of North: 33o 00 00.0 N, East: 093o 00 00.0 W , South: 32o 00 00.0 N, W est: 095o 00 00.0 W . At first, the calculation radius is placed at 5 km and the cell radius at 2 km, for all the cells in the network. Initially each BTS tower is kept at a height of 30 meters and antenna power at 20 watts. Additionally, all BTS sites had three sectors in each of them with a pair of frequencies assigned to each cell sector. These maintained appropriate co-channel, adjacent channel and composite interference, with the desired optimal C/I ratio of 20 dB. At the beginning, before fixing on the frequency cluster channel allocation pattern to be implemented in the network, first a single cluster is placed following the one in project specifications, and its predictions for forward propagation, reverse propagation, co-channel interference, adjacent channel interference, composite interference etc. were obtained. Then the frequency pattern of the cluster is changed and the same prediction results were obtained. W hen compared, the original frequency pattern was found to be giving more favourable results. Therefore the first frequency pattern is chosen to be implemented in the network, and it is documented later under the frequency planning section. Next, the number of the BTSs is increased to 24 (twenty four), each installed at the center of every cell. Again, simulation results for aforementioned predictions are obtained and checked and it was seen that the 24 BTSs didnt cover the network area in whole. Therefore, 9 (nine) more BTSs were added to the network with some of them having two sectors instead of three. Afterwards, the amounts of co-channel interference, adjacent channel interference and composite interference were checked repeatedly and BTS parameters were modified until appropriate outcomes were achieved.


7

Next, the traffic simulations were performed and observed that the number of transceivers was not enough to accommodate traffic that too, mostly in the same area where the most recently established BTS sites existed. Therefore 4 (four) extra BTSs were added and repositioned accordingly to avoid interferences. Then the final traffic simulations were performed and necessary results were documented. Once the traffic simulations were done with, the final step performed was to construct a backhaul network with two MSCs, each situated in every block of location. They connected with their respective BTSs within their own block as well as with themselves using appropriately mounted MW (Microwave) links.


8

2.1.1 General requirementsThe fundamental requirement of this project is to plan, design and replicate a functional and cost-effective cellular mobile telecommunication network for a given area, through the use of computer-aided software. In this context, the project specifications should be analyzed as requirements and the appropriate ones should be fulfilled to satisfy the operational requirements economically. The general requirements are the first step of planning a GSM cellular network. This usually includes Adequate coverage Appropriate service quality Economic convenience Performance efficiency Optimal use of system resources Through the course of this project construction, all related parameters comply with these general requirements in order to successfully roll-out the proposed GSM 900 telecommunication network.


9

2.1.2 System parameters

Figure 2.1: System param eters


10

2.1.3 Mobile terminal parameters2.1.3.1 GSM-900 Mobile Terminal

Figure 2.2: GSM-900 mobile terminal param eters


11

2.1.4 Mobile environment parameters2.1.4.1 Pedestrian

Figure 2.3: Pedestrian environm ent param eters


12

2.1.4.2 In vehicle - Handheld

Figure 2.4: In-vehicle environm ent param eters


13

2.1.4.3 In building - Handheld

Figure 2.5: In-building environm ent param eters


14

2.1.5 Service class parametersService class parameters allow input parameters related to the mobile terminal and the overall coverage area, to be classified in three different conditions. They are chosen as below

Figure 2.6: Service class param eters

Here, class 1 associates GSM 900 mobile terminal with pedestrian environment, class 2 conjuncts GSM 900 mobile terminal with in vehicle-handheld environment and class 3 attaches GSM 900 mobile terminal with in building-handheld environment.


15

2.1.6 Base station parametersBase station parameters are one of the most essential elements in planning and optimizing a network. There are several factors to be determined here, an example of those are shown below

Figure 2.7: Base station param eters

W ithin a base station, constraints like antenna type, antenna tower height, antenna orientation, antenna tilting, antenna power, center frequency etc. are vastly important and therefore, carefully analyzed and implemented.


16

2.1.6.1 Base station antenna type parametersConsidering parameters like radiation pattern, beamwidth, gain, diameter, frequency range etc. two types of antennas were selected for using in BTS towers. The first one was antenna 7416-11 and the second one was 7416-14.

2.1.6.1.1. Antenna 7416-11

Figure 2.9: 7416-11 3D radiation pattern Figure 2.8: 7416-11 param eters

This antenna is used in most of the BTSs for optimal coverage, nominal power intensity, moderate dimension and appropriate frequency range. The radiation pattern and the elevation beamwidth here show that the antenna is capable of covering a good amount of geographic area, since the front lobe of the radiation pattern is much larger compared to the back lobe while the azimuth and elevation beamwidths stand at good amounts of 120o and 65o respectively. As for power intensity, nominal gain of 5.5 dBd with a wider beamwidth give an acceptable increase in antenna output power to more ground in a particular direction, for both transmission and reception. Also, a dimension of 1.5 m provides easier installation and a frequency range of 870 960 MHz makes it ideal for GSM operation since GSM frequency range is 890 960 MHz.


17

2.1.6.1.2 Antenna 7416-14

Figure 2.11: 7416-14 3D radiation pattern Figure 2.10: 7416-14 param eters

This antenna is also used in a few BTSs for directional coverage, increased power intensity, moderate dimension and appropriate frequency range. The radiation pattern and the elevation beamwidth here show that the antenna is capable of covering a some geographic areas more directly as well as areas in close proximity of some BTSs, since the front lobe of the radiation pattern is much larger and direct compared to the back lobe with a sharp 16o elevation beamwidth angle along with 120o azimuth beamwidth angle and also, has some sidelobes present in the radiation pattern. As for power intensity, again a nominal gain of 5.5 dBd combined with narrower beamwidth give an acceptable increase in antenna output power to a narrower area in more precise direction, for both transmission and reception. Again like 7416-11, a dimension of 1.5 m provides easier installation and a frequency range of 870 960 MHz makes it ideal for GSM operation.


18

2.1.6.2 Antenna tower height parametersAccording to the project specification, base station antenna height should be kept under 30m in urban areas and under 80m in rural and quasi-rural areas. In urban areas where topographic elements comprise of structures, buildings, population etc., it is both impractical and unsafe to build much higher towers since they would result in more maintenance cost, disruption of skyline, more vulnerability towards damage etc. Besides, since urban areas do not have dense vegetation or grasslands, propagation paths are not disturbed much and therefore, extra height in towers is unnecessary. On the other hand, due to presence of natural elements like trees, shrubs, grasslands, forest etc., signal disruption, scattering and diffraction are caused resulting in inefficient signal propagation. To avoid this, towers are built at a longer height to clear such areas that cause signal propagation disturbances.

2.1.6.3 Antenna orientation parametersAntenna orientation is a very important aspect in the design of mobile base station networks to confirm adequate coverage in all areas and ensures proper cell sectoring. In this project, the default antenna orientation is intended for BTS sites with 3-sector cells, as shown in the figure below

Figure 2.12: Antenna orientation for 3-sector cell


19

2.1.6.4 Antenna tilting parametersAntenna tilting is the process of focusing a BTS antenna more towards the cell grounds, in order to avoid overshooting of signals in high power antenna into adjacent cells. This is done to prevent interference that is caused by two adjacent signals with same or adjacent channel frequencies colliding with each other. Antenna tilting is mostly done in urban areas that have smaller cell sizes.

2.1.6.5 Antenna powerThe usual antenna power range for this project is set at 15-50 W atts and in extreme cases, a maximum of 60-80 watts range can be applied to ensure adequate coverage. Antenna power range is fixed to avoid unnecessary interfering signal propagation to unwanted areas such as nearby cells. Besides, extra power can cause wasting of equipment resources and also increases cost. Thus power control for BTSs allows prevention of interference as well as minimizes cost and optimizes equipment uses.

2.1.6.6 Center frequencyThe center frequency is responsible for defining the operating frequency range of a BTS. In this project, the center frequency in each BTS is fixed at 925 MHz in co-ordination with the GSM frequency spectrum, since GSM operates at 890-960 MHz frequency range and so, 925 MHz falls at the center.


20

2.1.7 Backhaul network parametersThe backhaul network sets up connectivity between each radio cell site in a network to a mobile switching center (MSC) to perform functions like call switching, handover, internetworking, billing etc. MSCs in a network can be single or multiple (depending on the size and capability of the network itself), but always viewed as one single unit. In this project, the connectivity is provided through LoS MW links which allow communication between each cell site with the MSC and also the MSCs themselves. The important parameters in a backhaul network link include general network antenna parameters, network link parameters, network site parameters, network forward link parameters and network reverse link parameters etc. with different values for each individual link.

Figure 2.13: Param eters of a network link


21

Figure 2.14: Param eters of 1st radio site

Figure 2.15: Param eters of 2nd radio site


22

Figure 2.16: Param eters of a network forward link

Figure 2.17: Param eters of a network reverse link


23

2.1.7.1 Backhaul network antennaThe type of antenna needed for microwave links should have narrowest possible beamwidth and much higher gain with moderate dimensions. Therefore, antenna HP4-107 was used in this case which served the purpose just right.

2.1.7.1.1 Antenna HP4-107

Figure 2.19: HP4-107 3D radiation pattern Figure 2.18: HP4-107 param eters

This antenna is also used in the backhaul network for absolute directional coverage, higher power intensity, moderate dimension and high frequency range. The radiation pattern and the elevation beamwidth here show that the antenna is capable of providing directional connectivity with sharp 1.6 elevation and azimuth beamwidth angles and also, absence of back and sidelobes indicate LoS coverage without signal scattering. As for power intensity, again a very high nominal gain of 38.3 dBd combined with a very narrow and sharp beamwidth give a higher increase in antenna output power directed towards one particular direction, for both transmission and reception. Again like BTS antennas, a dimension of 1.2 m provides easier installation and a frequency range of 10500 11700 MHz is more appropriate in MW transmission links.


24

2.1.8 Path loss model parametersThe path loss model specifies the amount of loss in BTS antenna transmission power while propagating through the atmosphere. In this project, model number I, Lee Model is used as the path loss model since it is based around the 900 MHz frequency, basis of GSM technology. The parameters of Lee model can be as follows

Figure 2.20: Lee m odel param eters


25

2.1.9 Geographical parameters2.1.9.1 Total service areaThe geographical data provided with CelPlanner consists of topographical, morphological, and map image data that include the city of Shreveport, Louisiana, LA, USA. A representation of this area can be as follows

Figure 2.21: Total service area

The geographical area intended to be used in this project is bounded by the following coordinates North: 33o 00 00.0 N South: 32o 00 00.0 N East: 093o 00 00.0 W W est: 094o 00 00.0 W

The area where the topographical, morphological, and map image layers coincide will be referred to as the Total Service Area or TSA in the context of this project. The measurements of this area are 93 km east-west and 111 km south-north (10,323 km2).


26

2.1.9.2 Local service areasThe total service area is divided into 36 rectangular-shaped areas of 18.5 km x 15.5 km as shown in the figure below. These areas are termed as Sub-service Areas or SSA.

Figure 2.22: Sub service area

For this project, two SSAs were selected which were SSA 10 and 11, alternatively known as blocks 10 and 11, as shown below

Figure 2.23: Sub service areas/blocks 10 & 11Telecommunications Design

27

2.1.9.3 Topographical dataThe topography covering SSA blocks 10 and 11 mostly have elevations approximately in the range of 30-130 m. The co-ordinates for different topography resolutions within the simulation software can be divided as per following

2.1.9.3.1 Resolution: 1 secondNorth: 33o 45 00.0 N South: 32o 15 00.0 N East: 093o 30 00.0 W W est: 094o 00 00.0 W


The topography simulation can be represented as belowFigure 2.24: Topography of SSA blocks 10 & 11

Figure 2.25: Topography sim ulation legendTelecommunications Design

28

2.1.9.4 Morphological dataThe morphology of SSA blocks 10 and 11 involve a variety of elements as follows Morphology Type: 0 1 2 3 4 5 6 7 8 Open W ater W oody W etlands, Emergent Herbaceous W etlands Perennial Ice/Snow, Bare Rock/Sand/Clay, Quarries/Strip Mines/Gravel Pit, Transitional Grasslands/Herbaceous, Pasture/Hay, Row Crops, Small Grains, Fallow Shrubland, Orchards/Vineyards/Other Deciduous Forest Evergreen Forest Mixed Forest Urban/Recreational Grasses

10 Roads 12 Low Intensity Residential 13 High Intensity Residential 14 Commercial/Industrial/Transport



29

The morphology simulation for SSA blocks 10 and 11 is provided below

Figure 2.26: Morphology of SSA blocks 10 & 11

Figure 2.27: Morphology simulation legend


30

2.1.9.5 Map image dataAs previously mentioned, the network area is contained within Shreveport, Louisiana, USA. Therefore, two maps of the area are provided below

Figure 2.28: Shreveport area im age II (100k)

Figure 2.29: Shreveport area im age III (250k)Telecommunications Design

31

The Shreveport map images fall under different scales with different co-ordinates Scale: 1:250,000 (250k) North: 33o 00 00.0 N South: 32o 00 00.0 N Scale: 1:100,000 (100k) North: 33o 00 00.0 N South: 32o 00 00.0 N Scale: 1:24,000 (24k) North: 32o 45 00.0 N South: 32o 15 00.0 N East: 093o 30 00.0 W W est: 094o 00 00.0 W East: 093o 00 00.0 W W est: 094o 00 00.0 W East: 092o 00 00.0 W W est: 094o 00 00.0 W


32

2.1.10 Frequency planning parameters2.1.10.1 Cell clustering parametersCell clustering is the process of combining a group of cells which doesnt include the same frequency twice. Corresponding to each cluster size, theres a reuse distance upto which, the same frequency is not repeated. A cluster can include different number of cells like 1, 3, 4, 7, 9, 12 etc. The more the cluster size, the more efficient performance a network would offer, but it is more expensive to implement as well. The cluster size assigned for this project is 4. The frequency channel allocation arrangement of that cluster is shown in the figure below

Figure 2.30: Cluster of four base station sites

2.1.10.2 RF channels numberingThe following table presents RF channels numbering for cellular cluster size of N = 4. The table is not built in within the network simulation software so it had to be created and saved for that program.1A 1 13 25 37 49 61 73 85 97 109 121 2A 2 14 26 38 50 62 74 86 98 110 122 3A 3 15 27 39 51 63 75 87 99 111 123 4A 4 16 28 40 52 64 76 88 100 112 124 1B 5 17 29 41 53 65 77 89 101 113 2B 6 18 30 42 54 66 78 90 102 114 3B 7 19 31 43 55 67 79 91 103 115 4B 8 20 32 44 56 68 80 92 104 116 1C 9 21 33 45 57 69 81 93 105 117 2C 10 22 34 46 58 70 82 94 106 118 3C 11 23 35 47 59 71 83 95 107 119 4C 12 24 36 48 60 72 84 96 108 120

Table 2.1: Channel numbering tableTelecommunications Design

33

2.1.10.3 GSM 900 channel planThe GSM 900 network has a frequency band of 890 960 MHz, with 890-915 MHz to send information from MS (Mobile Station) to BS (Base Station) (uplink) and 935960 MHz for data transmission from BS to MS (downlink). This frequency band provides 124 RF channels (channel numbers 1 to 124) with each being 200 kHz in width. Duplex spacing of 45 MHz is used while guard bands of 100 kHz at the end of each frequency range [4]. A representation of this channel plan is given below

Figure 2.31: GSM 900 MHz frequency arrangem ent


34

2.1.11 Teletraffic planning parametersA very important part on successful network roll-out is to ensure proper traffic handling with the least blocking probability. This was done either by increasing number of transceivers for base station areas with more traffic or by installing new BTSs in high traffic areas, wherever needed. Again in doing so, interference minimization is carefully considered. Teletraffic planning parameters includedTraffic grid parameters, traffic simulation parameters, traffic load allocation, teletraffic distribution etc.

2.1.11.1 Traffic grid parametersTo distribute traffic over the whole network area, the first step would be to create the traffic grid. This involves the following parameters

Figure 2.32: Traffic grid creation param etersTelecommunications Design

35

2.1.11.2 Traffic simulation parametersThe primary teletraffic simulation elements for this project would be Erlang formula, Grade of Service (GoS), teletraffic load allocation etc. The Erlang formula used here is Erlang B, GoS used is 3% and teletraffic load allocation in total is 430 Erlang. The simulation elements can be seen in the figure below

Figure 2.33: Traffic simulation parameters


36

2.1.11.3 Traffic load allocationAs per project specifications, the traffic allocated to SSA blocks 10 and 11 are 170 and 260 Erlang respectively, therefore, the total traffic load would be [170 (block 10) + 260 (block 11)] Erlang = 430 Erlang The traffic load allocation matrix is therefore provided below. Here, the number in bracket is the block no. and the other one is the allocated Erlang for that block

Figure 2.34: Teletraffic load allocations


37

2.1.11.4 Teletraffic distributionTeletraffic can be distributed uniformly or corresponding to morphology factors throughout the service area. The following figure shows all those morphology factors that influences teletraffic within the scope of this project

Figure 2.35: Morphology factors in traffic allocationTelecommunications Design

38

2.2 Planning toolThe computer aided software used for the planning, designing and implementation of the proposed network within the scopes of this project is called CelPlannerTM 9.3. CelPlanner is one of the main components of the industry acclaimed CelPlanner Suite, the most complete and integrated suite of software tools addressing the complexity of W ireless Networks design from conception to implementation [10].

Figure 2.36: CelPlanner software window [10]

CelPlanner is an advanced integrated software tool that addresses today' and tomorrow's W ireless Network Planning and Design needs by supporting wireless access technologies such as 4G (W iFi, W imax, DVB-H), 3G (IS-2000, 1xRTT, UMTS), 2.5G (GPRS/EDGE), 2G (cdmaOne, IS-95, IS-136, TDMA, GSM), and analog (AMPS, ETACS), thus allowing seamless and smooth network planning evolution for wireless operators and associates [10]. CelPlanner comprises of several elements, among which, the following were used in this projectDatabases, predictions etc. project databases, propagation analysis, traffic/load analysis,


39

2.2.1 DatabasesCelPlannerTM uses several, key databases to simulate accurate prediction of RF. These databases areIndividual and composite predictions, frequency groups, antenna, topography, morphology (clutter), image (satellite, aerial photography, or maps) etc. All these databases work from their respective directories as selected manually by the user.

Figure 2.37: Database directories


40

2.2.2 Project databasesThe project database includes global system parameters, prediction parameters, prediction adjustment factors, prediction configuration, terminal configuration, environment configuration, service classes, MSC, BSC, radio base station, contours prediction, prediction threshold, phase, areas and flags, vector elements, database directories, user data files, colour table, co-ordinate systems etc. These function based on individual input parameters as provided by users.

Figure 2.38: Project param etersTelecommunications Design

41

2.2.3 Propagation analysisThis involves predictions on path loss for signal propagation based on any of the four modelsModified Lee-Picquenard based Model (Model I), Korowajczuk-Picquenard Model (Model II), Microcell Model (Model III) and Stanford Model (Model IV). Of these, Model I is implemented for this project. This model calculates attenuation between BS and MS using two factorsMorphology and topography. In this propagation model, diffraction loss is obtained by the knife-edge model while gain and attenuation factors are obtained through studies on topographical influences on these factors. The parameters of this model are provided below

Figure 2.39: Prediction param eters for Lee m odel


42

2.2.4 Traffic/load analysisIn CelPlannerTM, users can create traffic grids with different resolutions with inputs applied through various methods. A fixed amount of traffic can be distributed across the CelPlannerTM database. Traffic data can be obtained directly from the demographic data or, from the switching equipment in operational telecommunication systems. Additionally, users can distribute the demographic data corresponding to morphological types, thus inducing a much more thorough traffic distribution [9]. An example of CelPlannerTM traffic distribution is as follows

Figure 2.40: Traffic distribution


43

2.2.5 PredictionsCelPlannerTM is capable of providing accurate simulation predictions for different parameters in a GSM network. Of these, the following were implemented in the projectIndividual forward traffic, individual reverse traffic, composite forward traffic, composite reverse traffic best server traffic, service classes, bit error rate, number of servers, handoff, co-channel interference, adjacent channel interference and composite interference. The prediction configuration parameters for this project are provided below

Figure 2.41 Prediction configuration param eters


44

Figure 2.42 Prediction threshold levels


45

3. Cellular Network Solution


46

3.1 Network ConfigurationThe GSM 900 telecommunication network planned within this project has been subjected to different approaches that helped it evolve to a more appropriate model. This process involved distinct configuration parameters applied through various means. The final network stood with 37 (Thirty seven) BTS sites, almost no interference, 430 (Four hundred and thirty) Erlang traffic, 2.2 (Two point two) percent blocking probability, two MSCs, 38 (Thirty eight) MW links and 100 (One hundred) percent network coverage. In the end, some sites followed the cluster frequency arrangement as mentioned earlier in the report in section 2.1.9.1 but others, especially some of those in the edges of the network area, didnt maintain the cluster pattern and were allocated frequency channels rather randomly, but strategically to avoid any channel overlap that would cause interference. A screenshot of this network with BTS arrangement is provided below

Figure 3.1: GSM 900 network arrangem ent with cell areas


47

In this above arrangement, the area contained within the rectangular grids is the actual geographic area set for the proposed network. It is notable that the BTS towers in this arrangement are not placed following any fixed arrangement, in order to provide ample coverage in every corner of the allocated SSA blocks of 10 and 11. The idea here is to maintain a signal coverage level of -80 to -95 dBm across the network area, covering as much area as possible. To achieve that, not only BTS tower locations are varied, but other parameters like BTS power level, antenna type, antenna mounting structures, antenna orientation for cell sectoring, etc. are considered as well. Another factor determined was to avoid any interference as much as possible, through measures like cell clustering, frequency channel allocation with appropriate reuse distance, antenna tilting, cell size modification etc.


48

3.1.1 Base station locationEach base station is placed strategically in the cell in a cell radius-overlapping manner, to cover all network areas without inducing significant co-channel interference. It should also be mentioned that some BTSs are put on higher grounds to provide adequate coverage without the need of extending antenna heights. This in turn also helps maintain LoS for MW links within the backhaul network. The following would depict how BTS sites are located in a manner where they randomly can overlap each others circular cell areas

Figure 3.2: BTS area locations


49

3.1.2 BTS power levelThe BTS power levels, in compliance with the project specifications, has been set within the range of 15-50 W atts for almost all the sites, with the rest few at 60 watts, citing extreme lack of coverage. The BTS sites, for which 60 watt power is used, are strategically placed to avoid possible interferences. In regions especially urban areas where taller BTS towers were needed for ensuring better coverage, antenna power was increased instead of the tower height since the specifications instructed the towers to be maximum 30 meters there. However, since only a few sectors implement 60 watts of power and make full use of it, therefore both cost and system resources remained at optimal levels.

3.1.3 Antenna typeIn accordance with the project specifications, the two antennas used in this project are 741611 and 7416-14. The antenna 7416-11 is installed in BTSs mostly in the center of the total network area to cover as much ground as possible. On the other hand, the 7416-14 antenna is mostly established in areas around the edges or in other areas where only a few ground was needed to be covered. This is because 7416-14 is more directional than 7416-11, capable of focusing to narrow areas.

3.1.4 Antenna mounting structureAccording to the project specification, base station antenna height should be kept under 30m in urban areas and under 80m in rural and quasi-rural areas. However in the project, base station antenna height was kept at maximum 30m in urban, and in rural and quasi-rural areas, since it provided ample coverage even upto that height. For mobile communication, the height of the antenna is a crucial factor in terms of both construction and performance. It is always feasible to mount


50

3.1.5 Antenna orientationAntenna orientation is a very important aspect in the design of mobile base station networks to ensure adequate coverage in all areas and ensures proper cell sectoring. In this project, most BTS sites used 3-sector cells while in some cells; 2-sector was implemented to avoid unnecessary equipment installation and uses, which in turn proved to be more economical. Along with this, some of the BTSs had a few of their antennas tilted in different sectors. Here, for both 3-sector and 2-sector antennas, different orientation patterns have been implemented, as shown in the figures below

Figure 3.3: 1st Antenna orientation for 3-sector cell

Figure 3.4: 2nd Antenna orientation for 3-sector cell

Figure 3.5: 3rd Antenna orientation for 2-sector cell


51

Figure 3.6: 1st Antenna orientation for 2-sector cell Figure 3.7: 2nd Antenna orientation for 2-sector cell

3.1.6 Cell clusteringAs mentioned before, the cluster size used in this project is 4, therefore, it induces a reuse distance of D = R3N

= 6.93 km So within each 6.93 km, no same two frequencies exist, reducing possibility of interferences to a high extent.

= 234

[R=Cell radius, N= Cluster size] [Initially, R = 2 km, N = 4]


52

3.1.7 Frequency channel allocationThis involves assigning one frequency channel to each transceiver in such a way that a separation of atleast 12 channels exist between each assigned frequency channel. The number 12 is chosen as the product of highest no. of sectors in a cell which is 3 and cluster size 4. The number of transceivers here depends on the traffic capacity, which would be discussed in a later section. Here, more the number of transceivers mean more frequency channels are assigned. An example of frequency channel allocation is given below

Figure 3.8: Frequency channel allocation i n a BTS


53

3.1.8 Antenna tiltingTo reduce interferences between any two cells which are much closer to each other than all the other cells, the common tilt amount used is 4 degrees. This indeed helped minimize the amount of interference significantly to make it negligible.

3.1.9 Cell size modificationThe calculation radius is the amount of area from the center of the BTS site upto which, the predictions are obtained through simulations. In addition with antenna tilting, adjustments on cell sizes by modifying calculation radiuses of interference-prone sites proves to be a highly effective method for successfully minimizing interferences. This along with antenna tilting, prevents overshooting of signals from high power BTS Antennas, resulting in almost no interference levels. Such cell size modifications are evident in below figures where the calculation radiuses are marked using a pattern

Figure 3.9: Calculation radius for all BTS sites

It is noteworthy that the area with more BTS sites has smaller calculation radiuses for those sites as they are in more risk of inducing interference.Telecommunications Design

54

3.2 Traffic channeling capacityIn this project, the traffic distribution through grid creation is initially obtained with two transceivers per BTS cell sector. Though this provided a 429.777 Erlang carried traffic 99.9% of the total 430 Erlang traffic, but it also induced a much higher system blocking probability of 116.34 Erlang i.e. 27.1 % of total traffic. Thereby, to minimize this blocking probability, more traffic channels were allocated either by including transceivers per sector, or put more BTS sites. After various attempts of this, traffic simulation was again executed and finally the blocking probability was reduced to 2.2%, with the carried traffic remaining the same, as shown below

Figure 3.10: Traffic channel suggestions


55

3.3 Backhaul networkThe last important aspect of this project was to ensure the switching functions, handover and mobility management through the implementation of a backhaul network. This network comprises of 2 (two) MSCs and 37 (thirty seven) BTSs, therefore includes a total of 38 (Thirty eight) MW links in the network. The network follows a star topology where each MSC acts as the central node to all the connected BTS nodes, so all the network connectivity depends on the MSCs. In this arrangement, failing of any links with the nodes doesnt affect the total network but failure of any MSC would disrupt the whole network. W ithin this network, the longest link distance for block 10 is 11.35 km (approx.) and shortest is 2.50 km (approx.), while for block 11, longest is 9.92 km (approx.) and shortest is 1.15 km (approx.). This network arrangement is as follows

Figure 3.11: Backhaul network arrangem ent

Some influential aspects of the backhaul network includeMSC placement, antenna type, antenna mounting, network link profile etc.


56

3.3.1 MSC placementIn this project, two MSCs were used in two different blocks for better connectivity purposes. Also, they were placed in a higher elevation around the center of each SSA block, for the purpose of maintaining proper LoS. The first MSC which is MSC1, installed at SSA block 10, sits at co-ordinates 323538.88 N and 934341.89 W . The second MSC, established at MSC2 is situated at co-ordinates 323502.79 N and 933436.92 W . The link distance between the two MSCs is 14.22 km (approx.).

3.3.2 Antenna typeConforming to the project specifications, the high gain directional antenna HP4-107 was used to ensure better LoS and connectivity with longer distances of upto 11.35 km. The very narrow elevation and azimuth beamwidths, much higher nominal gain, moderate dimension and a high a frequency range of 10500 11700 MHzall provided adequate support in maintaining undisrupted LoS and long distance connectivity.

3.3.3 Antenna mountingAs per convention, the MW antennas are mounted on such structures that they always get LoS links in between, clearing all morphology and topography elevations. Therefore, in this project, the tower heights for such antennas varied within the range of 15 - 40 meters approximately, considering different elevation heights in different parts of the networks geographical area.


57

3.3.4 Network link profileThe network link profile is a representation that provides all related information on each MW links. It allows the network planner to ensure that the links have adequate parameters set to function properly. Such parameters include MW antenna tower height, link distance, link polarization, total loss and many others as well. The network link profile also generates a graphical representation of the Fresnel zones and the LoS between the two ends of an MW link. The Fresnel zone is an ellipsoid area around the direct line between two communicating nodes [11].

Figure 3.12: Fresnel zone obstruction [13]

If the Fresnel zones blocked by an obstruction, e.g. hills, trees or buildings, the signal arriving at the far end would fade away. Therefore in construction of wireless links, the Fresnel zones should be kept as obstacle free as possible, practically about 60 percent of the radius of the first Fresnel zone [11]. However in the context of this project, all MW links have their Fresnel zones cleared of all obstacles. This is done by increasing link tower heights accordingly so that they clear all obstacles and achieve LoS.


58

The Fresnel zone ellipsoid radius, is expressed by the following formula F n = 17.32

d1 d2 fd

W here, F n = Fresnel zone ellipsoid radius

n =1, 2, 3 is the Fresnel zone number with n=1 means First Fresnel zone, n=2 means second Fresnel zone and so on d = Distance (in km) between the receiver and transmitter f = Antenna operating frequency (in MHz) d1 = Distance (in km) from transmitting antenna to path obstruction d2 = Distance (in km) from receiving antenna to path obstruction [12]


59

3.3.4.1 Network link profile of two MSCs

Figure 3.13: MSC1 MSC2 link profile

This figure above represents the MW link between the two MSC sites where MSC1 resides in position 323538.88 N and 934341.89 W while MSC2 stands at 323502.79 N and 933436.92 W . The link distance between the two MSCs is 14.22 km (approx.) For this link, each towers antenna is mounted at 40 m height above ground in order to get proper LoS connectivity. The ellipsoids in the middle represent the Fresnel zones while the red vertical lines on the sides represent the antenna towers. Since it is a bidirectional link, both nodes transmit and receive signals. In between the towers, lie the topographical and morphological elements.


60

Some of the parameters in this link profile are shown below

Figure 3.14: MSC1 MSC2 link profile param eters


61

3.3.4.2 Network link profile of longest link in SSA 10

Figure 3.15: MSC1 BTS19 link profile

This figure above represents the longest MW link in SSA block 10, between MSC1 and BTS19, where MSC1 is established at 323538.88 N and 934341.89 W while BTS19 stands at 323047.97 N and 934808.41 W . The link distance between them is 11.35 km (approx.) For this link, each towers antenna is mounted at 25 m height above ground in order to get proper LoS connectivity. The ellipsoids in the middle represent the Fresnel zones while the red vertical lines on the sides represent the antenna towers. Since it is a bidirectional link, both nodes transmit and receive signals. In between the towers, the topographical and morphological elements are depicted.


62


Figure 3.16: MSC1 BTS19 link profile param eters


63

3.3.4.3 Network link profile of longest link in SSA 11

Figure 3.17: MSC2 BTS11 link profile

This figure above represents the longest MW link in SSA block 11, between MSC2 and BTS11, where MSC2 is positioned at 323502.79 N and 933436.92 W while BTS11 is installed at 323026.45 N and 933751.45 W . The link distance between them is 9.92 km (approx.) For this link, MSC2 tower antenna is mounted at 30 m height above ground while BTS11 tower antenna is mounted at a higher 40 m height above ground in order to get proper LoS connectivity. The ellipsoids in the middle represent the Fresnel zones while the red vertical lines on the sides represent the antenna towers. Again it is a bidirectional link as both nodes transmit and receive signals. In between the towers, lie the topographical and morphological elements.


64


Figure 3.18: MSC2 BTS11 link profile param eters


65

4. Discussion and critique


66

4.1 General overviewThe initial planning and design of this GSM 900 telecommunication network involved 24 (Twenty four) BTS sites following the cluster of 4 (Four) frequency channel allocation pattern mentioned earlier. Also, initially each BTS tower was kept at a height of 30 (Thirty) meters with the 7146-11 antenna and each antenna power set at 20 (Twenty) watts, considering the presence of urban morphology where higher height of antennas is impractical and difficult to construct. It is then observed that 24 BTSs were not enough to cover all the network area, especially over the urban morphological elements, unless the heights of the towers and/or the antenna powers are modified for a few BTS sites. However, since going beyond the originally allocated 30 meters height is neither practical nor economic for an urban area, particularly within urban areas. Therefore, it was considered more useful to put extra BTSs to increase coverage in the network blocks. As a result, 9 (nine) more BTS sites were added and strategically placed within the network, which in turn increased the coverage to a perfect 100%. These new sites, however, didnt form any clusters as they were randomly placed in areas with less than expected signal coverage. At this point, some of the other BTS towers were also repositioned from the centre of each initially allocated cell area which proved much fruitful in ensuring more coverage. Once ample coverage was ensured, traffic allocation simulation was performed and though almost all the traffic were carried through this network arrangement, a much higher system blocking probability prevailed, which could have resulted in more call dropping within the network. Thereby, to minimize this blocking probability towards a value less than the allocated GoS, , the choice was to either increase the number of transceivers or increase the number of BTSs again to accommodate the extra traffic channels. However, the first option required more than 3 (Three) transceivers to be implemented in some of the cell sectors, which is economically unfeasible and also puts pressure over BTS equipments. As a result, 4 (Four) more BTSs were put in the network design, over areas where more traffic distribution existed. Though the extra BTSs accommodated the increased traffic, their presence created some unwanted co-channel interference as well as composite interference levels less than the desired 20 dB. To avoid all that, re-positioning of some of the BTSs as well as tilting of antennas were performed until the co-channel interference was significantly minimized and C/I ratios were improved beyond 20 dB. Still, 3 BTS sites (BTS16, BTS17 and BTS18) needed at least 4 (Four) transceivers for a total of 3 sectors, more than the desired number, but considering minimizing of the co-channel interference, no more BTS sites were placed and instead, the extra transceiver implementation was allowed.Telecommunications Design

67

The next stage of network designing involved establishing a backhaul network controlled by one or more MSC(s). In this project, though one MSC was enough for performing switching function with all the total 37 BSCs, two MSCs were established. The idea behind using two MSCs was to ensure LoS between each MSC-BTS pair. Since the morphology was such that putting only one MSC would require higher mounting of MW antennas which is economically inconvenient, as well as create more distance between some MSC-BTS pairs, one MSC was installed at each block to ensure better LoS and decrease distances for each MSC-BTS pair. Besides, two MSCs are much useful in providing redundancy, in any case if any of them fails. The general approach in establishing this network was to maintain adequate coverage, handle all existing and upcoming traffic and ensure proper switching among network elements, based on the most cost-effective approach achievable. Though the initial approach was to use as less BTS sites as possible, in the end, more BTS sites were put up within the network. This had been certainly done to ensure proper coverage as well as traffic capacity handling. Beside, more number of BTS sites would also leave room for future expansions. So the number of BTS sites used here is certainly justified. Overall in this project, the best efforts were put to achieve the maximum favourable outcomes in planning, designing and establishing a GSM 900 network, with proper research and testing. The best thing about this network design is that it is always open to any modification or expansion whenever needed, making it more adoptive and acceptable.


68

4.2 Difficulties encounteredDuring the course of the project, several difficulties were faced that caused delays in achieving the desired outcomes. For example, at the beginning, eliminating interference while maintaining adequate coverage was achieved after much trying and testing with BTS repositioning, antenna tilting, adjusting BTS power and antenna height etc. This proved quite time-consuming since removing interference would result in subtle spots with lack of coverage across the network while in turn ensuring proper coverage with more BTS sites would mean introducing unwanted interference again. Another aspect of difficulty was encountered while installing newer BTSs to accommodate extra traffic. This resulted in the problem of co-channel interference since the BTSs had to be positioned much closer to each other. Eliminating this became the most difficult of all since if the BTSs were not placed accordingly; they would either fail to accommodate traffic channels without the use of undesired high number of transceivers or would get performance degrading co-channel interference. As a result, a more balanced approach was implemented in positioning the BTS sites properly after much exhausting efforts. This task therefore, was certainly the most challenging but in the end, was successfully carried out. Lastly, choosing the number of MSCs and placing them appropriately within the backhaul network was a bit trivial as well, nonetheless, handled with ease. Repeated checking were also done in determining the heights of the MW antennas for each MSC-BTS link, but it was not much daunting of a task and therefore, was the least difficult of all challenges. Since the morphological elements for both SSA blocks exhibited a difficult and complicated combination of urban, rural and quasi rural characteristics, a very steady and composed methodology was needed to successfully implement all proposed solution for the network in this project. This is the main reason contributing to the difficulties surfaced throughout the whole project and thankfully was handled in the extent of achieving much constructive outcomes.


69

4.3 Meeting current and future requirementsThe proposed GSM 900 telecommunication network is certainly successful in maintaining current requirements, following the project specifications. It provided adequate coverage with almost no interference; was capable in handling the traffic to an acceptable amount with a desired blocking probability and maintained proper LoS connectivity for switching purposes to all nodes in the backhaul network. The overall design would seem a bit more expensive with 37 BTS sites, but is certainly commendable in ensuring that the fundamental requirements are met in rolling-out of a telecommunication network. Some of the other requirements met within the scopes of the proposed network include Maintaining -80 to -95 dBm power for most areas in the network appropriately modifying calculation radiuses for BTS Sites whenever needed to eliminate interference Effectively positioning BTS sites; maintaining C/I ratio of atleast 20 dB use of maximum 3 transceivers per sector in most BTS sites maintaining BTS antenna height maximum at 30 meters retaining BTS antenna power at a maximum of 60 W atts using BTS antennas suitable for GSM frequency spectrum using an antenna with adequate gain, having moderate diameter for easy installation using less sectors in some BTS antennas for cost-effective approach maintaining appropriate antenna orientation for areas that needed more direct transmission clearing obstacles in path of the Fresnel zones for all links in the backhaul network etc. Since high number of BTS Sites are used within this project, they can be successfully used in future network expansions through options like cell sectoring, cell splitting etc. Also, as BTS towers even in rural and quasi-rural areas are kept at 30 meters, they can be further increased upto 80 (Eighty) meters of height in future needs. Additionally, upto 3 transceivers can be added in sectors using less than that, to accommodate extra traffic channels, if ever needed. Along with this, use of two MSCs would easily allow to handle and adopt to any changes within the BTS nodes. This would also be used for MSC redundancy in case any of the MSCs get operational disruptions.


70

4.4 Observations from the projectThe purpose of completing this project was based on achieving partial requirement of 25% of the total course load in the degree of Master of Telecommunication Engineering (Coursework). However, this project proved much helpful in noting additional observations within the studies of Telecommunication network, enriching the knowledge of the individual involved with the project. Some key points among them would include Understanding and performing hands-on tasks involved in a GSM 900 cellular mobile network planning, design and implementation through simulation using the highly efficient CelPlannerTM software Ensuring the rolling out of a telecommunication network satisfying RF coverage with no interference, proper traffic handling and better switching provisions among network nodes with backhaul network connectivity Learning about different characteristics of telecommunication network configuration as the following Base station location BTS power level Antenna type Antenna mounting structure Antenna orientation Cell clustering Frequency channel allocation Antenna tilting Cell size modification

Getting experienced in traffic channeling capacity maintaining negligible interference Understanding following parameters in establishing a backhaul network MSC placement with clear LoS Antenna type Antenna mounting Network link profile


71

5. Appendices


72

5.1 Project specificationsCelPlannerTM has a unique option of providing all the specifications of the elements of this project based on the GSM 900 telecommunication network. The specifications include the following parameters System Parameters Prediction Parameters - Prd 1 Prediction Adjustment Factors - Ajt 1 Prediction Configuration Service Classes Prediction Thresholds Project Phases, Areas and Flags Vector Element Files Access Directories Project Color Table Cell site data Antenna data GSM R4/12 15 MHz Frequency Table


73


74


75


76


77


78


79


80


81


82


83


84


85


86


87


88


89


90


91


92


93


94


95


96


97


98


99


100


101


102


103


104


105


106

5.2 CelPlanner outputs5.2.1 Individual forward class 1

Figure 5.1: Class 1 individual forward prediction of the central BTS site (BTS2C)

Figure 5.2: Legends for class 1 individual forward prediction

Individual forward prediction shows the individual coverage prediction from the BTS site in focus to all MS under it. The individual forward prediction for class 1 of BTS2C, the central BTS site, is calculated here for upto a 5 km radius and covers 11% of the total network area for the signal level range of -80 to -95 dBm.


107

5.2.2 Individual forward class 2



The individual forward prediction for class 2 of BTS2C, the central BTS site, is calculated here for upto a 5 km radius and covers 9% of the total network area for the signal level range of -80 to -95 dBm.


108

5.2.3 Individual forward class 3



The individual forward prediction for class 3 of BTS2C, the central BTS site, is calculated here for upto a 5 km radius and covers 5% of the total network area for the signal level range of -80 to -95 dBm.


109

5.2.4 Individual reverse class 1

Figure 5.7: Class 1 individual reverse prediction of the central BTS site (BTS2C)

Figure 5.8: Legends for class 1 individual reverse prediction

Individual reverse prediction shows the individual coverage prediction from all MS to the BTS site in focus. The individual reverse prediction for class 1 of BTS2C, the central BTS site, is calculated here for upto a 5 km radius and covers 12% of the total network area for the signal level range of -80 to -95 dBm.


110




The individual reverse prediction for class 1 of BTS2C, the central BTS site, is calculated here for upto a 5 km radius and covers 11% of the total network area for the signal level range of -80 to -95 dBm.


111



Figure 5.12: Legends for class 3 individual reverse prediction

The individual reverse prediction for class 3 of BTS2C, the central BTS site, is calculated here for upto a 5 km radius and covers 5% of the total network area for the signal level range of -80 to -95 dBm.


112

5.2.7 Composite forward class 1

Figure 5.13: Class 1 Composite forward prediction

Figure 5.14: Legends for class 1 composite forwar d prediction

Composite forward prediction shows the combined coverage prediction from the all BTS sites to all MS within the network. The composite forward prediction for class 1 covers 100% of the total network area for the signal level range of -80 to -95 dBm.


113




The composite forward prediction for class 2 covers 99% of the total network area for the signal level range of -80 to -95 dBm.


114




The composite forward prediction for class 3 covers 87% of the total network area for the signal level range of -80 to -95 dBm.


115

5.2.10 Composite reverse class 1

Figure 5.19: Class 1 Composite reverse prediction

Figure 5.20: Legends for class 1 composite reverse prediction

Composite reverse prediction shows the combined coverage prediction from all the MS to the BTSs within the network. The composite reverse prediction for class 1 covers 99% of the total network area for the signal level range of -80 to -95 dBm.


116




The composite reverse prediction for class 2 covers 98% of the total network area for the signal level range of -80 to -95 dBm.


117




The composite reverse prediction for class 3 covers 86% of the total network area for the signal level range of -80 to -95 dBm.


118

5.2.13 Co-channel interference class 1

Figure 5.25: Class 1 co-channel interference prediction

Figure 5.26: Legends for class 1 co-channel interference prediction

Co-channel interference prediction shows the amount of signal disruptive crosstalk induced when two BTSs are transmitting in the same frequency. The co-channel interference for class 1 is visually negligible and 0% in amount when compared with the total network area.Telecommunications Design

119




The co-channel interference for class 2 is visually negligible and 0% in amount when compared with the total network area.Telecommunications Design

120




The co-channel interference for class 3 is visually negligible and 0% in amount when compared with the total network area.Telecommunications Design

121

5.2.16 Adjacent channel interference class 1

Figure 5.31: Class 1 adjacent channel interference prediction

Figure 5.32: Legends for class 1 adjacent channel interference prediction

Adjacent channel interference prediction shows the amount of signal disruptive crosstalk induced when two BTSs are transmitting in the adjacent frequency channels. The adjacent channel interference for class 1 is visually none and 0% in amount when compared with the total network area.Telecommunications Design

122




The adjacent channel interference for class 2 is visually none and 0% in amount when compared with the total network area.Telecommunications Design

123




The adjacent channel interference for class 3 is visually none and 0% in amount when compared with the total network area.Telecommunications Design

124

5.2.19 Composite interference class 1

Figure 5.37: Class 1 composite interference prediction

Figure 5.38: Legends for class 1 composite interference prediction

Composite interference prediction is the combination of co-channel and adjacent channel interference, expressed in C/I ratio values. Class 1 composite interference has atleast 20 dB C/I ratio for 1% of total network area while a C/I ratio of 40 to 127 dB for 55% of total network area.


125




Class 2 composite interference has atleast 20 dB C/I ratio for 1% of total network area while a C/I ratio of 40 to 127 dB for 55% of total network area.


126




Class 3 composite interference has atleast 20 dB C/I ratio for 1% of total network area while a C/I ratio of 40 to 127 dB for 55% of total network area.


127

5.2.22 Traffic distribution scenario

Figure 5.43: Traffic distribution scenario prediction based on topography

Figure 5.44: Traffic distribution scenario prediction based on morphologyTelecommunications Design

128

Figure 5.45: Legends for Traffic distribution scenario prediction

The traffic distribution scenario prediction shows 1.218 Erlang as the highest traffic intensity and 0.000 as the lowest.


129

5.3 Additional information as required5.3.1 Best servers class 1

Figure 5.46: Class 1 best server prediction

Figure 5.47: Legends for class 1 best server prediction

The best server prediction shows BTS sites with higher amount of acceptable signal levels and no handover occurrences[9]. For class 1, the best servers would be BTS1A, BTS5A, BTS4B, BTS2D, BTS3D and BTS6D at 4%.Telecommunications Design

130

5.3.2 Best servers class 2



For class 2, the best servers would be BTS1A, BTS5A, BTS4B, BTS2D, BTS3D and BTS6D a t 4 %.Telecommunications Design

131

5.3.3 Best servers class 3



For class 3, the best servers would be BTS1A, BTS5A, BTS4B, BTS2D and BTS3D at 4%.Telecommunications Design

132

5.3.4 Bit error rate class 1

Figure 5.52: Class 1 bit error rate prediction

Figure 5.53: Legends for class 1 bit error rate predicti on

The bit error rate prediction indicates the ratio of information bits with error and total number of bits for a network and It should be below or equal to 1.00 [9]. For class 1, 99% bit error rate is below or equal to 1.00 and 1% is greater than 1.00 and less or equal to 3.00.


133

5.3.5 Bit error rate class 2

Figure 5.54: Class 2 bit error rate prediction

Figure 5

ele5tde final project report-semester 2, 2011

Documents

subject ele5tde

trobe university victoria

australia subject

project works

network implementation

course of ele5tde

smte department of ee

ample network coverage