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Success Story
By Zou Yizhi, Qu Chengfu, Shi Jianqiang
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By optimizing the GSM network,
Guiyang Mobile (a branch of China
Mobile) improved the networkquality, balances network load,
realized E2E optimization, realized fast
subscriber growth and user perception
improvement, and successfully built a
network based on customer perception.
With the implementation of Western China
Development, the city of Guiyang sees a
rapid development in economy, culture,
science & education, transportation, and
telecommunications elds. As the spearhead
of communication in Guizhou province,
Guiyang Mobile has also continuously
accelerated the construction of mobile
telecommunications networks and is
committed to improving services and
boosting corporate image.
Guiyang city is located at Karst hilly
areas featuring complex landforms and
the relative altitude difference in city
areas reaches 100 meters. Due to the
concentration of users in down town areas,
densely distributed sites, large number of
narrow alleys, multi-layer in-building service
(IBS) distributions, and dense residential
areas in urban areas, users raise increasingly
higher requirements for coverage. In
addition, the single coverage type cannot
satisfy the complex and changing urban
environment. Tariff policy adjustment
drives the rapid development of diversied
services, causing a sharp increase in trafcvolume in some areas. In this way, network
bearer capacity is facing great challenges
and network structure in some areas needs
to be optimized. The requirements for
network quality, capacity, and coverage are
increasingly higher. Therefore, forging a
top-quality GSM network is top priority for
Guiyang Mobile.
To quickly improve the current network
status in Guiyang, Guiyang Mobile, together
with the SmartCare solution of Huawei,
proposed a principle of "Determining
Network Landscape, Eliminating Network
Quality Problems, and Improving User
Perception" to comprehensively improve
network quality after in-depth analysis
of networking, trafc, and geographical
conditions. In addition, Guiyang Mobile
adopted the following methods to realize
coordinated multi-product optimization,
FEB 2012 ISSUE 31
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Success Story
(Idea of the stereoscopic network integrating GSM900 with DCS1800)
900M sites in the two metropolitan areas are of high density. The frequencies have high reuse rate and high
frequency interferences, which brings tremendous challenges to the effective utilization of existing wireless
network resources. To reduce the inter-frequency interferences, balance traffic load, and optimize network
coverage, it is required to optimize the structure of the existing network. By building a dual-plane and
tridimensional IBS system, we can make full use of the 1800M resources and resolve the problems facing the
existing network once and for all by optimizing the two networks.
Cover older uptown and dense street by Street site
IBS1800M
Plane1: 900M
Plane2: 1800M
Tridimensional IBS
Tridimensional coverage (over 15F)Larger capacityHigher speed
Continuous coverage
of double plane
Continuous coverageLarger capacityHigher speed
(After the idea of the stereoscopic network is implemented, KPIs such as trafc
proportion, coverage of backbone roads, and speech quality are fully improved.)
By the end of July 2011, the project team successfully implemented thephase-1 & phase-2 frequency E network retirement project. By then, 1281800M macro sites totaling 1752 carrier frequencies and 42 1800M IBSsites totaling 158 carrier frequencies have been added to the network.The proportion of 1800M sites was increased from 33.48% to 40.95%on a year-on-year basis.
Continuously balance the load on 900M/1800M sites in the twometropolitan areas and customize the scenario switchover and parameterre-selection solution according to the actual situation in Guiyang to ensurethat the 1800M sites can effectively share the traffic. The proportion oftraffic absorbed by 1800M sites was increased from 28.81% to 43.70 ona year-on-year basis.
80.00%
60.00%
40.00%
20.00%
0.00%1800M Carrier Accounting 900M Carrier Accounting
2010.6 2011.6
40.95%33.48%
66.52%59.05%
80.00%
60.00%
40.00%
20.00%
0.00%1800M Voice Traffic Accounting 900M Voice Traffic Accounting
2010.6 2011.6
43.70%
28.81%
71.19%
56.30%
With the increase of 1800M sites, number of sites with high traffics isreduced, as well as the frequency interference. As a result, the voiceservice quality increased from 95.69% to 98.21% on a year-on-year basis.
Continuously improve the network coverage on roads. Because 1800Mfrequency has abundant resources and high voice service quality, 1800Mresources are generally used for improving the drive test result. Thecoverage of 1800M network was increased from 27% to 54.70% on ayear-on-year basis.
80.00%
60.00%
40.00%
20.00%
0.00%1800M Coverage Accounting
(Main Road)900M Coverage Accounting
(Main Road)
2010.6 2011.6
54.70%
27.00%
73.00%
45.30%
99.00%
98.00%
97.00%
96.00%
95.00%
94.00%
2010.6 2011.6
98.21%
95.69%
Voice Quality
located the problem points through a
large number of routine tests, complaint
handling, trafc maps, and coverage
prediction. In this way, Guiyang Mobile sets
up sites in areas where coverage is required,
improving coverage depth. To share thetrafc load on GSM900 networks, Guiyang
Mobile accelerated the construction of
entering the phase of fully improving
network quality.
1. Integrating GSM 900 Networks with
DCS1800 Networks
In view of the development requirements
of dual-band networks, Guiyang Mobile
DCS1800 networks to achieve continuous
coverage, laying a foundation for
reducing the number of sites with higher
conguration requirements and alleviating
frequency interference. In addition,
Guiyang Mobile exibly deployed sites onstreets or used remote radio units (RRUs)
to achieve coverage in multiple scenarios
instead of the original coverage by one
macro site. General packet radio service
(GPRS) and Enhanced Data rates for GSM
Evolution (EDGE) channels were enabled
on GSM900/DCS1800 MHz bands. In this
way, mobile stations (MSs) can initiate data
services at any frequency band, therefore
balancing the network load, reducing the
number of handovers between GSM900
and DCS1800 MHz bands, and improvinguser perception.
With the continuous exploration of the
stereoscopic network, by the end of July
2011, the proportion of DCS1800 MHz
carrier frequencies increased from 33.4%
in the same period in 2010 to 40.95%, and
key performance indicators (KPIs) such as
trafc proportion, coverage of backbone
roads, and speech quality were fully
improved.
2. Integrating the IBS Network with theStereoscopic Network
The increasing special locations in
urban areas, such as high buildings and
underground parking garages have
become a huge problem for outdoor
coverage. Facing the problems of increased
complaints about indoor connectivity on
the live network and an increasing number
of complaints about poor coverage in
small areas, Guiyang Mobile and Huawei
project team actively investigated the areaswhere the problems occur frequently and
adopted the stereoscopic coverage to
resolve the problems according to actual
local conditions. For VIP sites and high-
grade ofce buildings, Huawei IBS solution
was adopted to properly allocate sufcient
radio resources, therefore achieving
optimum coverage effects and improving
VIP customer satisfaction. For areas where
the capacity of outdoor sites failed to satisfy
the heavy trafc, such as stations, shopping
malls, and schools, IBS sites were set up to
absorb as many trafc as possible. By doing
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this, outdoor sites load was reduced, and
the impacts of trafc peaks on the entire
network were alleviated, ensuring the voice
quality of outdoor sites.
After the IBS project (Phase III) was
implemented, KPIs such as network radio
access, handover success rate, TCH call
drop rate, HQI, and interference band were
improved to varying degrees. Wherein, the
improvement of HQI and interference band,
1% and 5% respectively, was the most
evident.
3. Integrating the 2G Network with the
3G Network
If the 3G network shares the same
IBS system with the 2G network, the
bandwidth of the existing 2G IBS system
needs to be transformed; otherwise, the
3G indoor coverage network needs to be
designed again. Therefore, compatibility,interference, service bearer and sharing,
and capacity need to be fully considered
during the design of the 2G IBS system.
In addition, the Wireless Local Area
Network (WLAN) and WiFi terminals are
used in hotspot areas. For areas where
point-to-point (P2P) trafc takes a higher
proportion, the WLAN is deployed
preferentially. For areas on the 3G
network where absorption of data services
is insufcient, coverage is enhanced
and price leverage is used to drive the
development of data services.
With the implementation of a series of
optimization schemes to improve connectivity
and ultimately gain better user perception,the number of exceptions on the live network
decreases signicantly from 217 in January
2011 to 80 in July 2011. In June 2011, the
number of static users exceeded 20,000,000,
which is another milestone for Guiyang Mobile
after the number of static users exceeded
10,000,000 in 2008. In addition, network
quality of Guiyang Mobile ranks higher among
peers nationwide and the user penetration
rate in Guizhou province exceeds 75%. In the
preventive maintenance inspection of China
Mobile held in December 2010, Guiyang
Mobile surpasses other competitors.
FEB 2012 ISSUE 31
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