paper published in IRICT2017 conference

1. Planning and Optimization of LTE Radio
Access Network for Urban Area at Taiz City,
Yemen
Redhwan Q. Shaddad(&)
, Mohammed A. Abdulwadood(&)
,
Nada Y. Kuradah, Samar A. Alsharaie, Mohammed A. Qaid,
Amal A. Alramesi, and Akram A. Rassam
Faculty of Engineering and Information Technology,
Taiz University, Taiz, Yemen
rqs2006@gmail.com, ma.aljarady@gmail.com,
Nadayasin8@gmail.com, samaralsharaie@gmail.com,
Amalahmednada105@gmail.com, Akrma6781@gmail.com
Abstract. For Long Term Evolution-Advance (LTE-A), this paper aims to
minimize the cost of the radio link and the network infrastructure, taking into
account the distribution of subscribers, the location of the area to cover and the
quality of service constraints. The coverage and capacity planning, and its
optimization are proposed for the urban area at Taiz city, Yemen. This paper
involves hands-on simulation exercise on planning and optimization of LTE-A
network using ATOLL planning software tool. After LTE optimization by using
Automatic Cell Planning (ACP), Automatic Frequency Planning (AFP),
Monte-Carlo algorithm and neighbor planning, the coverage, signal level and
throughput have been improved. In addition, overlapping has been reduced. The
optimization process improves the coverage rate from 90% up to 98.04%,
Carrier-to-Interference-and-Noise Ratio (CINR) from 65.04% up to 77.6%, and
total traffic supported by the network increases after the optimization by 30%.
Keywords: LTE Á LTE-A Á 4G wireless communication Á Access network
optimization Á CINR
1 Introduction
The Long Term Evolution (LTE) & LTE-Advance (LTE-A) are rapid development of
wireless communication and multi-media applications such as Internet browsing,
interactive gaming, mobile TV, video streaming and audio streaming. The mobile
communication technology needs to meet different requirements of mobile data, mobile
calculations and mobile multi-media operations [1].
The LTE system is designed to be a packet-based system containing less network
elements, which improves the system capacity and coverage. The LTE system provides
high performance in terms of high data rates, low access latency, flexible bandwidth
operation and seamless integration with other existing wireless communication systems
[2]. These advantages and other significant performance achievements rely on recently
introduced physical layer technologies, such as Orthogonal Frequency Division
© Springer International Publishing AG 2018
F. Saeed et al. (eds.), Recent Trends in Information
and Communication Technology, Lecture Notes on Data Engineering
and Communications Technologies 5, DOI 10.1007/978-3-319-59427-9_31

2. Multiplexing Access (OFDMA), Multiple-Input Multiple-Output (MIMO) systems and
smart antennas [3]. In addition, the updated release of LTE supports inter-radio access
technology operation, enhanced Inter-Cell Interference Coordination (e-ICIC) and
energy efficiency [4].
Key Performance Indicators (KPIs) are indicators for if a device or equipment
meets a certain reliability criteria for being ready for deployment [5]. To meet customer
requirements for high-quality networks, the LTE trial networks must be optimized
during and after project implementation.
After the completion of all steps of planning for the wireless communications
network (coverage and capacity) and the creation of the network infrastructure at the
target urban area in Taiz city, many of the problems are affecting the performance of
the network. The first problem relates to the used techniques and devices. The other
problem relates to the geographical nature of the area where it is continuously
changing, for example, buildings and streets.
The overall objective of this paper is to optimize the LTE network after the
planning process. Radio network optimization involves the activities such as data
collection and data analysis of the implemented network and checking of the causes
which affect the network operation quality. By modifying the parameters and some
methods, the network optimization ensures that the network performance and resources
are optimized and provides appropriate suggestions for future network maintenance
and planning [6]. The software tool ATOLL radio planning and simulation is used to
simulate the proposed LTE network [7]. This paper is mostly proposed to optimize of
LTE network for urban area at Taiz city which has different geographic distributions of
nature and population.
2 Architecture of LTE Network
Architecture of LTE/LTE-A for the high-level architecture of the evolved packet
system (EPS) network is shown in Fig. 1. There are three main components, namely
the LTE user equipment (LTE-UE), the evolved Universal Mobile Telecommunication
System (UMTS) terrestrial radio access network (E-UTRAN) and the evolved packet
core (EPC). The interfaces between the different parts of the system are denoted
LTE_Uu, S1 and SGi [2].
The access network of the LTE, E-UTRAN, simply consists of a network of
evolved nodeBs (eNBs), as illustrated in Fig. 1. The eNBs are normally
inter-connected with each other by means of an interface known as X2, and to the EPC
by means of the S1 interface – more specifically, to the Mobility Management Entity
(MME) by means of the S1-MME interface and to the serving gateway (S-GW) by
means of the S1-U interface. The E-UTRAN provides air-interface user-plane and
control-plane protocol management for the users. It supports the following functions:
radio resource management, measurements, access-stratum security, IP header com-
pression and encryption of the user data stream, MME election, user-plane data routing
to the S-GW, scheduling and transmission of paging messages, broadcast information,
and public warning system messages [2].
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3. To improve the performance of the LTE networks there are many key techniques
must be considered such as: MIMO transmission, spectrum flexibility, bandwidth
flexibility, transmission schemes, and Inter-Cell Interference Coordination (ICIC)
Technology [8, 9].
There is a high probability of resource blocking which is located around cell edge
user to transmit by neighbor cell. This results in high interference, eventually low
throughput or call drops, as shown in Fig. 2. Traffic channel can sustain up to 10% of
Block Error Rate (BLER) in low Signal-to-Interference plus Noise Ratio (SINR) but
control channels cannot sustain up [10].
3 LTE Network Planning and Optimization
A fixed LTE planning in urban area of Taiz city is provided and the performance for the
basic minimal configuration based on the LTE system profiles is also supplied. The aim
of this paper is estimation of the approximate number of base stations needed to fulfill
the requirement on the coverage, the capacity and the quality of service (QoS). The
radio network planning and optimization process can be divided into different phases.
In the preplanning phase, the general properties of the future network are investigated,
for example, what kind of mobile services will be offered by the network, what kind of
requirements the different services impose on the network, and the basic network
configuration parameters.
Fig. 1. The EPS network elements.
Fig. 2. Inter-Cell Interference Coordination (ICIC) technology.
LTE Radio Access Network for Urban Area at Taiz City, Yemen 287

4. The second phase is the planning. A site survey is done about the to-be-covered
area, and the possible sites to set up the base stations are investigated. All the data
related to the geographical properties and the estimated traffic volumes at different
points of the area will be incorporated into a digital map, which consists of different
pixels, each of which records all the information about this point. The coverage
planning determines the service range, and the capacity planning determines the
number of to-be-used base stations and their respective capacities.
In the third phase, constant adjustment will be made to improve the network
planning. Through driving tests, the simulated results will be examined and refined
until the best compromise between all of the facts is achieved. Then the final radio plan
is ready to be deployed in the area to be covered and served.
The main aim of coverage planning is to estimate the coverage distance of a base
station with parameter settings derived from actual cell boundary coverage require-
ments sequentially to meet network size requirements. Planning strategies for LTE
coverage can be classified into uplink edge and downlink edge, since the uplink edge is
essentially applied in coverage. Capacity planning gives an estimate of the resources
needed for supporting a specified offered traffic with a certain level of QoS. Average
cell throughput is needed to calculate the capacity-based site count. The main indicator
of capacity is SINR distribution in the cell.
In this paper, the urban area of Taiz city is chosen. The chosen area is about
21.97 km2
with a population of 510,486 which is distributed into this region with
assume the same densities. After collecting all information about the area of planning
which was mainly given by Taiz Information Center [11], we start to calculate planning
parameters using Nokia Simense Network (NSN) Excel based tool. From the coverage
planning calculation, the sites number is 26 sites. On the other hand, there are 34 sites
according to capacity planning. So the largest number is chosen as it will satisfy the
requirements of both type of planning. The location of each region is then set using
Hexagonal tool which is available in ATOLL for the urban area considering inter-site
distance and the names of sites. According to the output of the tool, the expected
throughput for DL in the urban area is 52 Mbps/site, while the expected throughput for
UL is 12 Mbps/site.
Fig. 3. Urban area at Taiz city with sites and transmitter.
288 R.Q. Shaddad et al.

5. Figure 3 shows the area and the sites. The locations of sites in detailed planning (in
Google earth and ATOLL) are shown with sectorization type; antenna direction
tweaking and antenna tilt adjustment. ATOLL offers a series of standard coverage
predictions based on the measured signal level at each pixel.
An LTE network will have to be optimized after deployment to provide better
coverage, throughput, and lower latency. Based on the collected data, RF planning
engineers analyze the performance and may be decide to reconfiguration more eNBs
Fig. 4. Procedures of LTE network optimization.
LTE Radio Access Network for Urban Area at Taiz City, Yemen 289

6. and optimization the network. Network optimization is a process to improve the overall
network quality as experienced by the mobile subscribers and to ensure that network
resources are used efficiently.
The technology-specific integration of the optimization procedures with the sim-
ulation platform is shown in Fig. 4. Within each Monte Carlo snapshot, the throughput
is calculated iteratively until the performance of the system converges. In the outer
loop, the first automatic adjustment of the framework is done, in order to fulfill the
service requirements of the user. The optimization algorithm tests different configu-
rations for different parameters that have high reconfiguration costs in a real network
evaluation. Cell reconfiguration means configuration of a set of parameters referring to
the antennas and radio deployment. Those include the number of sectors, antenna
types, antenna direction in azimuth and tilt and antenna heights.
4 Results and Discussions
The LTE network is optimized as well based on some KPIs. The optimization process
improves the coverage rate from 90% up to 98.04%, CINR rate from 65.04% up to 77.6%,
and total traffic supported by the network increases after the optimization by 30%.
The peak radio link control (RLC) cumulated DL+UL throughput (kbps) is cal-
culated from all sites as shown in Fig. 5. The DL throughput reached maxima (above
40 Mbps) at the sites of Aljahmaliah, Alashrafiy, Kalabh, and Sinah because the
topography free area of barriers which are effect on the signal, unlike other area that
landforms and obstructions on the propagation path such as buildings, trees, mountains,
and hills. In addition, the DL throughput increases at these sites because existence of
interference between neighboring cells, which improve throughput.
Overlapping zone is an excessive overlap between some of the sectors on the site in
the network before optimization. The Fig. 6 illustrates this undesired configuration
excessive separation between some of the sector on the site and not enough separation
Fig. 5. Peak RLC cumulated DL+UL throughput (kbps).
290 R.Q. Shaddad et al.

7. Fig. 6. Overlapping zone before and after optimization.
Fig. 7. Coverage by DL signal level before and after optimization.
Fig. 8. Coverage by DL throughput after optimization.
LTE Radio Access Network for Urban Area at Taiz City, Yemen 291

8. on between the other sectors before optimization (dash red line). When may occur
multiple servers in the same geographic area that decrease the performance of network.
After optimization the number of servers decreased and reduced the waste of network
resource as shown in Fig. 6(solid blue line). The calculation is based on the reference
signal (RS) levels of the servers.
Figure 7 shows the coverage prediction by DL signal level before (dash red line)
and after (solid blue line) optimization. The best signal level is −72 dBm that cover
2.68 km2
before optimization as shown in Fig. 7. After optimization, the best signal
level is −72 dBm can reach to 19.4 km2
as shown in Fig. 7.
Figure 8 shows the coverage prediction by DL throughput before (dash red line)
and after (solid blue line) optimization. The peak DL throughput is 52 Mbps that cover
14.4 km2
before optimization as shown in Fig. 8. After optimization, the coverage
increased to 21 km2
with peak DL throughput is 52 Mbps.
Technique of LTE optimization improves coverage and the CINR, the required
CINR is the main performance indicator for LTE. In order to meet the defined quality,
antenna selection and parameter optimization (height, azimuth and tilt) have been
adjusted. The optimization results are achieved with 98% for LTE coverage and 77.1%
for CINR as shown in Fig. 9.
5 Conclusions
The main motivation for this paper was to provide simulation for multi-service radio
network planning and optimization for LTE radio access network in urban area at Taiz
city, Yemen. After LTE optimization by using ACP, AFP, Monte-Carlo algorithm and
neighbor planning, the coverage, signal level and throughput have been improved. In
addition, overlapping has been reduced. The coverage with enhancement of 98% and
the signal level with CINR increasing of 77.1% have been achieved.
Fig. 9. Graph of optimization result.
292 R.Q. Shaddad et al.

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