17622467 ELE5TDE FINAL PROJECT 1 1. INTRODUCTION 1.1 Background Mobile network management is a complex process that needs proper balance between cost factors and the target specification with the deployment of new technologies. Mobile Frequency spectrum and the antennas should be deployed very precisely because they need to last for many years of time. Moreover the increasing demand of data rates in mobile technology has raised the bars of need of physical infrastructures. This is where Long Term Evolution (LTE) technology comes into play. It is a different technology than the traditional GSM and CDMA mobile telephony. And because it is very cost acquiring project to implement directly such infrastructures, a simulation tool is very handy to use. 1.2 The Cell planner In this project, we are introduced to Cell Planner 11.5 software planning tool for designing and planning cellular mobile telecommunication networks. CellPlanner is an advanced software for the design and optimization of mobile radio networks. It helps in the planning and optimization which saves time and money during network establishment of 2G, 3G, WiMAX, and also the LTE networks. This tool helps in the deployment of a network and the simulation for a given area accordingly. 1.3 LTE (Long Term Evolution) antennas.[1] LTE provides the fastest mobile broadband service commercially available today. The high speeds are made possible by using more radio spectrum per connection, multiple antenna paths and more efficient encoding on the data sent and received. Some elements that are required to build an LTE are: Antennas and radio base station called eNode B A Transport Network(optical fibers and IP routers) A Gateway(connection to internet and IP networks) A mobility management entity(MME)
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1. INTRODUCTION
1.1 Background
Mobile network management is a complex process that needs proper balance between cost
factors and the target specification with the deployment of new technologies. Mobile
Frequency spectrum and the antennas should be deployed very precisely because they need to
last for many years of time. Moreover the increasing demand of data rates in mobile
technology has raised the bars of need of physical infrastructures. This is where Long Term
Evolution (LTE) technology comes into play. It is a different technology than the traditional GSM
and CDMA mobile telephony. And because it is very cost acquiring project to implement
directly such infrastructures, a simulation tool is very handy to use.
1.2 The Cell planner
In this project, we are introduced to Cell Planner 11.5 software planning tool for
designing and planning cellular mobile telecommunication networks. CellPlanner is an
advanced software for the design and optimization of mobile radio networks. It helps in the
planning and optimization which saves time and money during network establishment of 2G,
3G, WiMAX, and also the LTE networks. This tool helps in the deployment of a network and the
simulation for a given area accordingly.
1.3 LTE (Long Term Evolution) antennas.[1]
LTE provides the fastest mobile broadband service commercially available today. The high
speeds are made possible by using more radio spectrum per connection, multiple antenna
paths and more efficient encoding on the data sent and received. Some elements that are
required to build an LTE are:
Antennas and radio base station called eNode B
A Transport Network(optical fibers and IP routers)
A Gateway(connection to internet and IP networks)
A mobility management entity(MME)
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Home subscribers database
A policy management system
IP multimedia subsystem(To handle voice over LTE)
Everything starts from our personal handset device. Let’s say we are using voice over LTE phone
call, sharing video, and sending heavy emails all at the same time. The MME establishes the
connection to the end terminal and is responsible to the signaling to the end terminal. Using
LTE all our datae is sent and received using IP packets. Ip packets are like transporters off all our
datae like emails, voices and videos. This information embedded in packets is carefully sent to
the eNode B Base stations. Then the base stations take information in the packets through the
microwave link to the gateway, a system made out of several levels. The serving gateway routes
the data towards its journey. This is the pillar of exchange of information between mobile and
the packet networks. Then ignoring the technology involved, the data is routed according to the
destination address. While all this process are carried out, the policy management counts all
the data packets and applies policy rules according to the personal subscription plan. Some of
the advantages of LTE include:
Improved browsing and online experience.
Better performance of multimedia application.
Enhanced voice communications with higher voice quality and shorter call establishment
time.[1]
1.4 LTE Modulation Techniques
LTE uses the multiple input multiple out (MIMO) scheme with the combined modulation
techniques of QPSK and QAM.
I. Quadrature phase shift keying (QPSK): This is spectral efficient technique which uses 2 bits
transmitted per symbol. In LTE this modulation scheme is switched to cover farther areas than
the eNode B.
II. Quadrature amplitude modulation (QAM): QAM is the combined modulation technique of
phase and amplitude modulation. When the symbols are combination of amplitude and phase,
more bits can be carried per symbol. Example, 8QAM takes four carrier phases with two
amplitude levels to transmit 3 bits per symbol.
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1.5 Code rate
Code rates are the ratio of information bits to a coding process to the total number of bits
created by the coding process. If the coding rate =1/2 indicates for each information bit into the
coding process there will be 2 bits created for transmission purpose. Example, the 4Mbps data
rate is selected for the transmission output of 8Mbps.
1.6 Bit Error Rate (BER)
During any study interval, BER is the number of bit errors per total transferred bits. This is one
of the most important factor that keeps up with data fidelity across the medium.
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2. DESIGN OBJECTIVE AND CONSIDERATIONS
The real life cellular project is dependent on various external constraints apart from antenna
height and power. Microwave signals show various properties like reflection, refraction and
diffraction across the medium and topology.
Figure 1 Topography of the area[2]
Figure 2 Morphology of the area
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The major constraints introduced in this project are:
a) Topology: Topology is responsible for varying reflection, refraction and diffraction along
with the signal attenuation properties of the signal. Area given to us has various range of
altitude zones, starting from 30 m to 139m. Majority of the topology has an altitude of the
range 70-99 which is almost 50% of the area. Second majority altitude zone ranges from 40- 59
m and the least one is 130-139 m.
b) Morphology: Morphology describer the density and height of man-made obstructions.
Morphology is the study of vegetation and habitation of a particular region for example rura,
urban, sub urban etc. It is another important field of study in the design of cellular wireless
networks like LTE. Majority of the area are urban and dense urban area so the presence of tall
buildings and other obstructions are expected. There are also some high and low vegetation
areas where there is less human habitation. Our major concern was to provide high data rates
for the urban and dense urban areas.
We have used Cell planner as our simulation tool to meet certain target specified for the
project.
This project is divided into two sections
a) Non-sectored design: This part of the project aims to give coverage to the given area
with optimum data rate of above 10Mbps for all the regions. This is to be done by using non-
directional (omnidirectional) antenna.
b) Sectored design: This is the second part of the project that aims to give coverage to the
given area with data rate above 35 Mbps for 20% regions and above 12Mbps for rest of the
area. The antennas used are sectored directional antennas with sectoring angle as per the
requirement.[3]
2.1 Area: The given area has co-ordinates of
North 32°, 29’, 21.0” N;
South 32°, 21’, 00.9” N ;
East 093°, 44’, 50.0” W;
West 093°, 57’, 50.0” W
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2.2 System parameters: For system parameters configuration, topography and
morphology database needs to be enabled. This is done by selecting the specific area given to
our project group. The frequency table of GSM39 is selected. The base station (eNode B) height
is above the morphology and the subscriber antenna height is above the ground.
2.3 Radio configuration: Bandwidth is restricted to 10 MHz and the modulation schemes
of QPSK, 16-QAM and 64-QAM are selected for both parts. The difference is, code rate can be
varied for the second part whereas it should be constant at 1/3 for the first part. The Duplexing
mode for part 1 and part 2 are taken as FDD rather than TDD since our priority is data rate.
2.4 Service Configuration: Bit error rate on demand is 10-4. This is the maximum bit
error rate tolerable for both parts of the project.
2.5 Environment configuration: Mobility is selected as static for the first part whereas it
is selected as vehicular (120km/ hr) in the second part.
2.6 Radio Base station:
part 1: Antenna is omnidirectional with no sectoring done. Beam width of an omnidirectional
antenna is 360o which means that power is equally distributed in all the direction. While no
sectoring is done, there won’t be any significant interference due to the use of omnidirectional
antenna. We used AO1909 model with gain of 9 dBd, 1.5m diameter and the operational
frequency is 850 to 970 Mhz and the beam width can be shown in figure 1.
.
Figure 3 A01909 Antenna[2]
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Maximum power is allowed upto 80 Watts and maximum height is 15m. Channel resource can
be selected from 1-9.Part 2: The antenna is directional with 3 sectors. We used 7146-11
sectored antenna whose nominal gain is 5.5 dBd and operates at the frequency for ranges 0.87
GHz to 0.96 GHz. Beam width is an important parameter for any antenna which is the
measurement of power strength in a particular direction. Its azimuth beam width is 120o and
elevation Beam width is 65o. This means that power is concentrated in a particular direction,
thereby reducing the interfering regions for other BTS.
Figure 4 7146-11 Antenna[2]
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3. Simulation analysis and results
By the initial study of the topology, our plan was to mount antennas with lower heights to the
high altitude zones so that the coverage will be assisted by the topology. We didn’t succeed in
some areas spots because Some of the regions in the area (Example Top right corner) although
were dense urban area, the antenna placement was hindered with the topology barrier and
morphology itself. So, we had to deploy relatively high number of BTS for those specific areas.
As per the design objective of the project, we have used the minimum number of BTS with
highly optimized antenna heights and antennas power. Unlike open space, real time cellular
network coverage depends on various external constraints as mentioned already. Yet we
obtained the coverage area of 90% with the required data rates for both parts. As the summary
of our results, we obtained tradeoff is the key lesson of every experiment which will be
discussed in the detail further.
3.1 Part 1: Non sectored design.
This part of the project is a basic non sectored antenna design. One of the major advantage of
using non-sectored design in the project is, there are more channels available for a particular
region which results in the increased trunking efficiency. We have put 22 LTE base stations
deployed across the area so that we could achieve 90% of coverage with above 10 Mbps. The
table for antenna height and power is given at appendix A table 1.The average power is 61.73
watts and the average height is 13.18 m
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3.1.1 Composite signal level.
Figure 5 Composite SIgnal Level(Downstream) Figure 6Composite Signal (upstream)
The maximum signal intensity for downstream is -80dBm which is present for 99% of the area
and for upstream, there is -80 dBm for 84% , -85 dBm for 14% and -90dBm for 2% of the total
area. There is non-uniform pattern seen in the upstream because for downstream, the
transmitter is radio base station whereas for upstream, the base station is receiver and user
equipment is a transmitter which cannot transmit at high intensity for far distances.
3.1.2 Composite SNR
Figure 7 S/N for upstream Figure 8 S/N for downstream
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Maximum Signal to noise ratio for downstream is 50dB whereas it is 40dB for the upstream.
3.1.3 Maximum data rate / user
Figure 9 Maximum data rate for downstream
Figure 10 Maximum data rate for upstream
The maximum data rate of any LTE base station is highly dependent upon the modulation
scheme and the code rates. The maximum data rate thus obtained for downstream is above 10
Mbps for 90 % of the area. For 8% of the area we have given a coverage at above 2 Mbps which
is not suitable for high speed data connection but sometimes call connectivity is more
important. Thanks to QPSK with lower code rates. We could deploy more Base stations but that
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would cost us a lot just to increase a small coverage region. So we decided to optimize between
antenna heights and power with minimum number of base stations required.