Chapter1 Network Planning Overview

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Wireless Network Planning Table of contents

Table of contents

Chapter 1 Network Planning Overview ......................................................................................21.1 Network Planning Flow .....................................................................................................21.2 Network Pre-planning .......................................................................................................4

1.2.1 Outline of the Network Pre-planning .......................................................................4

1.2.2 Pre-planning Foundation ........................................................................................5

1.2.3 Pre-planning Process .............................................................................................6

1.2.4 Pre-planning Difficulties ........................................................................................14

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Wireless Network Planning Chapter 1 Network Planning Overview

Chapter 1 Network Planning Overview

1.1 Network Planning Flow

The purpose of the network planning is to construct a wireless network, whosecapacity and coverage area are both as large as possible and which can adapt to thenetwork development and capacity extension in the future, at a certain cost andguaranteeing the network service quality.

The network planning is a systematic engineering, which covers the whole process ofthe network construction, from the wireless transmission research to the antennafeeder equipment specification analysis, from the network capacity prediction to thedetailed project design, from the network performance test to the adjustment andoptimization of the system parameters, large as the general design idea, small aseach cell parameter; the network planning is also a comprehensive technique, whichrequires the knowledge in multiple aspects from wired to wireless, and abundantpractical experiences.

The telecom providers mostly concern the service quality provided by the system,whose most important factor is the coverage area. At the same time, when thewireless frequency resource is limited, how to increase the network capacity and howto meet the requirement of the network development in the future have to beconsidered while designing. All of the above-mentioned problems need to be solvedthrough the network planning, which will realize the benign balance in coverage,capacity, quality, cost and so on.

See Figure 1-1, the Network Planning Flow

Figure 1-1 Network Planning Flow

The first phase is traffic coverage analysis. The purpose of traffic coverage analysis isto provide the foundation for the network planning. It needs to collect the followinginformation: cost, capacity, coverage, quality, grade of service (GoS), availablefrequency band, information of the increase of the system, population distribution,income distribution and the fixed telephone set subscription, etc.

The second phase is emulation. The emulation is the site planning of the subscriberdistribution with the help of the planning software. The purpose is to guarantee thecoverage and capacity of a certain area and avoid the interference. In this phase, the

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Huawei Company applies the network planning software ASSET.

The third phase is reconnaissance survey. Perform the field examination following theideal station address book. Record the possible station addresses according to thedifferent construction conditions (including power supply, transmission,electromagnetic background and land taken over, etc.). Consider the range ofdeviation from the ideal stations, effects on the cell splitting, economic benefit,coverage area prediction and so on. Then recommend a suitable station address planand make sure if the electromagnetic environment around the base station is pure.

The fourth phase is the system design. Set the frequency, the planning of theadjacent cell and running parameters of each cell, according to the actual basestation distribution and station type.

The fifth phase is installation and debugging. Following the design data, install anddebug the system to make it run normally.

The sixth phase is optimization. Along with the increase of subscribers, the networkneeds frequent optimization and adjustment. When the traffic hits a certain amount,the network needs expand the capacity; thus it returns to the phase of traffic coverageanalysis.

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1.2 Network Pre-planning

1.2.1 Outline of the Network Pre-planning

The pre-planning is the basic of the wireless mobile network. It reflects the systematicdesign level of the network planning and decides the layout of the future network.

The output content of the pre-planning includes: the base station distribution, channeldistribution, cell data and so on. Its major tasks are as follows

(1) Analyze the construction units companys requirements of the coverage area andthe capacity.

(2) Decide the position of the ideal station according to the cellular structure.

You may select several key points in the area, from where you can observe with thehelp of a local relief map or an administration map, and mark the most dense regionsof the subscribers as the addresses of the stations to be constructed at the first step.Then mark other base stations on the map according to the ideal cellular structure.

(3) Analyze and decide the structure of the network and the base stations.

Firstly, analyze and decide if its necessary to construct a Hierarchical Networkaccording to the subscriber distribution, transmission conditions and the citydevelopment plan; and then analyze and decide to apply the omnidirectional ordirectional station to meet the requirement of coverage and capacity according to thedifferent places of the area.

(4) Compute the cell channel number of each base station.

Predict the traffic according to the geographic location of each basestation, and look up into the ERL table to get the number of channels to beconfigured for each base station according to the call lost ratio index

Estimate the type of the largest base station according to the frequencybandwidth provided by the construction unitcompany. If it cannot meet thecapacity requirement of the local area, it needs to add the number of basestations following the principle of cell splitting according to the realconditions. It also needs to select the ideal station locations on the mapand estimate the base station channel number again.

(5) Predict the coverage area and decide the base station project data, namelyperform the preliminary emulation

Select the design index:

Select the minimum input power and the penetration ratio index at the coverage areaedge.

Select the design parameters: antenna height (above the ground), antenna

azimuth angle and gain, antenna declination angle, base station heightabove sea level, base station type, feeder line length and antenna feedersystem loss, combining and distribution methods, transmitter output power,receiver sensitivity, base station diversity reception and diversity gains andso on.

Predict the coverage area of each base station cell according to thepropagation models of different regions. Deliver the adjustment opinionsfor the base station address, antenna direction, declination angle, andheight according to the potential blind area and weak signals. And get theproject data of the real base station in the end.

(6) Select the real station address and decide the station type.

Perform the field examination following the ideal station address,

according to the different construction conditions (including power supply,

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transmission, electromagnetic background and land taken over, etc.).Record the possible station address. Then propose a suitable addressscheme based on the integrating consideration of the deviation range fromthe ideal address, effects on the future cell splitting, economic benefit andcoverage area prediction and so on.

After selecting the address, decide the real station type according to thenumber of the base station channel.

After decided the station type, it needs to conduct an antenna feederconfiguration scheme. As to the network moving, it needs to investigatesufficiently the antenna feeder combination of the original manufacturer,the development of the planned base station capacity and the antennacombination supported by the current equipments and deliver the bestcombination scheme of the antenna feeder.

(7) Frequency and Adjacent Cell Planning

Make the frequency and adjacent cell plan according to the real base stationdistribution and type.

(8) Cell Data Making

1.2.2 Pre-planning Foundation

I. Service Area Requirements and Traffic

The traffic distribution and coverage requirement of a certain area is one of thefoundations of the network planning and generally provided by the constructionunitcompany. In the case without clear requirements, you should carry out the fieldinvestigation and analysis, make sure which area has coverage and capacityrequirements to met meet and which area has so little subscribers that its noteconomical to construct a station. You may ignore or reduce the service quality index.You should distinguish the short-term and long-term objects of the network

construction. Mark these data and traffic distribution data on a geographical or a cityplanning map on the scale of 1/50000 or 1/200000. In the case of lacking trafficdistribution data, you can mark how much percent each different area accounts forthe assumed total subscriber number.

Since the network construction is divided into different phases, the overall coverageand capacity requirements of an area cannot be realized from the very beginning.Generally, at the beginning of the network construction, when there are only a littleafew subscribers, the consecutive covering of the network should be focused on; in thelate phase of the construction, improving network service quality is generally theobjective.

II. Information of the Adjacent Network

For good preparation of the local network planning, it needs to collect the informationof the network constructed in the adjacent related areas (including the coverage areadesign and frequency design of the adjacent base stations along the dividing line.)

III. Landform and Field Object Data

Landform data: champagne, flat, hill, mountainous area and water, etc.;

Field object data: human environment, like city, urban, countryside,transport artery (including the newly built buildings, roads and scene pointsand so on), etc.; floor building data, like the building type, constructiondensity distribution and ground vegetation (forest, grassland and crops,etc).

The pre-planning is in the early stage of the wireless mobile network construction andthe most important phase. It reflects the system design level of the network planning.

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The pre-planning decides the layout, quality and development space of the futurenetwork

1.2.3 Pre-planning Process

I. Coverage Analysis

(1) Type of the Coverage Area

Different signal propagation models are applied for the areas of different types, whichdecides the design principle, service level and frequency re-use pattern of thewireless network of the coverage area. In order to decide the coverage area of thecell, you can divide the wireless coverage area into several types: big city, middle-sized city, small town and countryside.

Area type Description

Big cityWith dense population, developed economy, large traffic.In the center of the city, high buildings stand in greatnumbers, and the shopping cente is flourishing.

Middle-sized city

With comparatively dense population, rather developedeconomy, fairly large traffic. In the center of the city,stand the dense buildings. The shopping center is ratherflourishing and very promising.

Small town

With a big population, promising economic development,moderate amount of traffic. In the center of the town,buildings stand rather densely. The shopping center hasa certain scale and rather promising.

CountrysideWith a population in low density, developing economyand rather low traffic.

In the connection area between the above-mentioned areas, there are varioustransport arteries, including: speedway, national highway, major provincial highway,railway and sea-route, common provincial highway, railway and sea-route, and so on.It also includes some roads in the mountainous areas. These areas need covering

too.

Generally, it is suggested to apply the Omnidirectional Coverage in the countryside onthe plain and the areas with limited landform, and the Directional Coverage in the big,middle-sized and small cities and speedways.

(2) Define the Field Strength of the Edge of the Coverage Area.

The field strength defining of the falling edge of the service area concerns: mobilesensitivity -102dBm, quick fading protection 4dB (3dB for countryside), slow fadingprotection 8dB (6dB for countryside), and noise (environmental and interfering noises)protection 5dB.In the big and middle-sized cities, consideration should be taken forthe indoor requirements; as to the outdoor requirement, the average insertion loss 15dB; and plus the indoor signal improvement storage, 5dB. Generally speaking, thepropagation fading of the GSM1800 signal is averagely more than that of theGSM900 signal by 8dB, the antenna gains of the GSM1800 system is averagely morethan that of the GSM900 system by 3dBSince the wireless links have up and downdirections, and the coverage area is defined by the weaker direction, it needs toconsider of the balance of the uplink and downlink. Before constructing an idealnetwork, its necessary to make a good power budget and keep the balance of theuplink and downlink as much as possible.

(3) Define the Coverage Ratio

The defining of the coverage ratio is different according to different coverage areas,and gradually improved along with the consecutive construction of the network. InChina, at the beginning, the outdoor full coverage is generally realized in cities,national significant tourism areas, speedways, national roads, areas along therailways with large traffic, as for other major roads, railways and sea-routes, the

network planning and construction should be performed for 90% of the object. Along

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with the deeper network construction and the increasing subscriber number, therequirement of the network service becomes higher and higher. At the same time ofnetwork planning according to the traffic, it needs to gradually enhance the indoorcoverage construction of the significant areas (for example, government offices, presscenters, airport lounge buildings, subways, top grade commercial office buildings,

entertainment centers and large shopping malls. What needs to explain is that,according to the domestic regulations, the network can be accessed from 90% of thearea and 99% of the time. This requirement should be enhanced in the outdoor areasof the big cities and simplified in the countryside. As to the transport arteries, differentstandards should be applied, and the consecutive covered blind areas should belimited according to the different artery types.

II. Network Structure Analysis

While considering the layout of the base station, it needs to analyze deeply thenetwork structure. Generally, the network can be divided by layer into high layer,middle layer and low layer station. Most of the network traffic is carried by the middlelayer base station.

(1) Middle Layer StationThe middle layer station of the big and middle-sized cities refers to the base station,whose antenna is generally 25~30 meters high and a little higher than the averageheight of the buildings, and installed on the top of the buildings, and which generallycovers several blocks. Most of the base stations in the small towns and countrysideare middle layer stations, except of some special high layer stations constructedbecause of the traffic direction control or landform. On one hand, the middle layerstation can efficiently apply the frequency resource (better than the high layer station),on the other hand, it can efficiently absorb the traffic (better than the low layerstation). It has been carrying most of the traffic generated in the network running.Except in the countryside, the average station distance between most of the twomiddle layer stations ranges from 0.6 to 5km; while in the big cities, there are alsosome areas, whose average station distance between the middle layer stations is

under 0.6km. But even in the big cities, the average station distance between middlelayer stations is suggested not to be under4km0.4Km. If more of the station distanceis reduced, the buildings will affects the signal strength between each base stationsmore obviously, even to a degree out of control and that no suitable floor objects canbe applied, thus the network service quality cannot be guaranteed; based on theexperiences of the project construction and maintenance, the address selection,design and construction of the base station, network maintenance and quality controlwill face a very big challenge.

(2) High Layer Station

The high layer station in the big and middle-sized cities refers to the base station,whose antenna is generally 40 ~ 50 meters high and much higher than the averageheight of the buildings, and whose coverage area covers several middle layer base

stations. Since the high layer station cannot make full use of the frequency resource,it should only be considered of and constructed, or changed from the original basestations, in big cities and some special middle-sized cities with many high buildings.The high layer station address selection should follow the principle of little butextractive. The high layer station is constructed mainly to solve the coverageproblem of the high buildings in the cities.

Some high layer stations are also constructed in the suburb, road, small towns andcountryside because of the traffic direction control and wide coverage.

(3) Low Layer Station

The low layer station refers to the base station, whose antenna is less than 20 metershigh and lower than the average height of the buildings. The antennas are generallyinstalled on the outside wall of the lower floors of a building, building group, the top of

the low roof garden or somewhere, or the rooms of a building. The coverage area

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only includes a street, part of a street or the rooms of a building. The low layerstations are frequently used. But they have rather low capacity of absorbing thetraffic, mainly because the coverage area of the low layer station is small, when astation departs a little from the hot traffic center, it can hardly have an ideal traffic.Therefore, the low layer station construction needs you to consider if the purpose of

construction is to supplement the coverage or solve the problem of high traffic, whichwill affect the address selection and the scale defining of the low layer station.

After the field investigation with the help of the map, the general network structurecan be decided. Generally, at the early stage of the network construction, single layernetwork design is applied, most base stations are middle layer station, when the basicnetwork is established, the new base stations will be added of adjusted according tothe traffic and coverage requirement. In the extremely high traffic area of the densecommercial areas, the low layer stations are constructed with the microcell layer anddistributed antenna system, which meets the requirement of the indoor coverage, andat the same time avoids the interference and difficulties of station selection due to thetoo short distance between stations. The low layer stations will develops into thelayered network structure.

III. Capacity Analysis

(1) Capacity Prediction

The network construction requires the consideration of economical feasibility andrationality. Only after predicting the network capacity of the early stage and the latestage, you can make a reasonable investment decision. The network capacityprediction should be based on the integrating consideration of the populationdistribution, family income, fixed telephone subscription ration, national economicaldevelopment and city construction, etc. The different charge policy is also animportant factor when the subscribers decide to access the network or not. Aftergetting the predicted total capacity of the network construction, you need to predictthe subscriber distribution density. Considering the real requirement of the project, thebase stations are generally constructed in the city, suburb and transport artery. So the

percentage ration can be applied for the prediction. At the early stage of the networkconstruction, the subscribers in the cities account for more percentage of thepredicted total subscribers, along with the deeper development of the networkconstruction, the subscribers in the suburbs and along the transport arteries willincrease in the percentage. Generally the traffic of each subscriber from a city and asuburb is 0.025Erl and 0.020Erl respectively.

The traffic calculation formula is: A=n/3600

In this way, the speech channel needed for a special base station can be predictedaccording to the traffic prediction.

Caution:Its necessary to consider of the effects of the cell splitting while calculating thespeech channel number.

In the GSM system, the ERL model is applied to calculate the density of the traffic,which can be carried by the network. The call loss applies 2% or 5% depending onthe real conditions.

Limited by the cell coverage area and the bandwidth of the available frequency, thecell capacity should be planned reasonably and the channel usage ratio should beraised as much as possible without affecting the good voice quality. As to the trafficshare of the two bands in dual band network construction, the looser frequencybandwidth can be used to realize the high usage ratio of the channels.

In the real networking, on the premise of guaranteeing the network quality at a certain

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level, there are two capacity solutions, namely a few stations with high levelconfigurations and any stations with lower level of configurations. They have obvioussuperiority and inferiority, which should be considered according to the differentconditions of each area.

In the network construction, the new base station construction and base stationcapacity expansion are two methods to increase the capacity. Different capacityexpansion strategies, like adding 900M/1800M base station, sector capacityexpansion, microcell and indoor coverage and so on, are applied for the areas ofdifferent traffic density.

After defining the total capacity, decide the number of the base station (cell) and thebase station configuration according to the frequency re-use pattern, integrate thecoverage requirements (appearing as the antenna interface EIRP requirements), andfinally select the suitable base station type and the combination of theCombiner/divider unit, antenna and the feeder line.

(2) Cell Splitting

The cell splitting is an effective way of network capacity expansion. It includes theperformance of splitting a large omnidirectional base station into several sector cellsand splitting the sector cells into smaller cells. In another word, it means the planningof different cell radius according to the traffic density of different areas. The cellsplitting means to construct more base stations and increase the system constructioninvestment. Its necessary to consider the following factors:

Be able to keep the image repetition of the frequency re-use regularity;

Make the existing base stations still usable;

Reduce or avoid the transition area;

Without affecting the consecutive splitting.

Since the cell splitting is fairly important, we hereunder make some more descriptionof the common cell splitting measure of 1 into 4.

The cell splitting is a way to split the congested cell into smaller cells. Each cell hasits own base stations. The antenna should be shortened and the transmitter powershould be reduced accordingly. Because the cell splitting increases the re-use time ofthe channel, the system capacity is increased. The number of channels in a unit areais increased through setting new cells with smaller radius than the original ones andfitting these cells (called as microcells) among the original cells. And the systemcapacity is increased accordingly. Suppose each cell is split by half of its radius, seePicture 1-2:

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Figure 1-2 Cell Splitting (1 in 4) Schematic Diagram

In order to cover the whole service area with these smaller cells, about 4 times of theoriginal cells are needed Ddraw a circle with the radius R to make it easier tounderstand. The circle with the radius R covers the area 4 times large as the areacovered by the circle with a radius of R/2. The increasing number of the cell increasesthe cluster number in the coverage area and then the channel number in thecoverage area, thus the capacity is increased. The cell splitting allows the systemgrowing through the smaller cells, instead of the larger cells, without affecting thechannel distribution strategy necessary for keeping the minimum co-channel re-usegenes between the co-channel cells. The Picture 1-2 is an example of cell splitting,the base station is placed on the corner of the cell. Suppose that the traffic in servicearea of the base station A is saturated (namely the congestion of base station A isover the acceptable value). Therefore new base stations are needed to increase the

channel number in the area and reduce the coverage area of each single basestation. In the example showed in Picture 1-2, the smaller cells are added on thepremise of not changing the frequency re-use plan of the system. The cell splittingjust zooms out the geometric shape of the cluster pro rata. Thus, the radius of eachnew cell is half of that of the original ones.

As to the new smaller cells, the transmission power should be reduced. Thetransmission power of the new cell, whose radius is half of that of the original one,can be given by checking the power Pr received from the edge between the new andoriginal cells, and letting them equal. This needs to ensure that the frequency re-usescheme of the new microcell is the same as that of the original cell. As to the Picture1-2:

Pr[at the edge of the original old cell] P t1Rn

1

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and

Pr[at the edge of the new cell] P t2(R/2)n

2

Here, Pt1 and Pt2 represent the base station transmission power of the larger andsmaller cells respectively, n represents the path attenuation index. If let n=4, and let

all powers received equal, then

Pt2=Pt1/16 3

That is to say, in order to cover the original coverage area with the microcells andreach the S/I requirements, the transmission power should be reduced by 12dB.

In fact, not all cells split at the same time. Generally, its very difficult for the serviceproviders to find the exact period suitable for the cell splitting. So the cells in differentscales exist simultaneously. Under this condition, it needs to maintain the minimumdistance between the co-channel cells, therefore the frequency distribution becomeseven more complex. At the same time, attention should be paid to the problem ofhandover so that the high speed and low speed mobile subscribers can enjoy theservice simultaneously. As shown in the Picture 1-2, when there are two scales ofcells in one area, the formula (3) tells that the original transmission power cannot be

simply applied for all of the new cells and the new transmission power also cannot beapplied for all of the original ones. If all cells apply the bigger transmission power,some channels used by the smaller cells wont be able to separate from the co-channel cells. On the other hand, if all cells apply the lower transmission power,part of the area of the bigger cell will be excluded from the service area. Accordingly,the channels in the original cell should be divided into two groups, one of which meetsthe re-use requirement of the smaller cells, and the other one of which the biggercells. When the bigger cells are used for high speed mobile communication, the timeof handover will be reduced.

The size of the two channel groups is decided by the splitting progress. At the earlystage of the splitting progress, the channels in the low power group are less.However, more channels of the lower power group are needed to meet the increasing

demand. The splitting progress will not stop until all channels in the area are used inthe lower power group, and then the cell splitting will cover the whole area and theradius of each cell in the system becomes smaller. The antenna is often declined tofocus the emission energy toward the ground, instead of on the horizontal direction, inorder to limit the wireless coverage of the newly formed microcell.

The above analysis tells that the coverage area design of the wireless network will notonly solve the problem of the coverage area, but also meet the subscriber capacityrequirement. The problem of the coverage area will be solved through constructingmultiple base stations/cells. However, the construction of the base station is limited bythe investment and restricts with each other. While the subscriber capacity is decidedby the channel configuration, limited by the frequency resource and restricting eachother. Therefore a unified planning is necessary.

IV. Station Address Planning

The purpose of the station address planning is to select the best location for the basestation. After the field examination, construct the base station in the center of a citywith a safe subscriber prediction, then gradually enlarge the number of the basestation on the map based on the principle of the cell mesh radius. Thus the idealstation address is selected. In the areas of different traffic density, the space betweenthe base stations is different. Generally, in the area of high traffic density, the spacebetween stations should be small, and the microcell and distributed antenna areapplied in part of the hot spots to provide the multi-layer coverage and meet thecapacity requirement. In a real project, its difficult to select the address. This is firstlybecause the irregularity of the landform and buildings causes the uneven signalcoverage figure. On the other hand, the interference has to be avoided. In other

words, not only the coverage but the interference should be considered beforepositioning the antenna. As to the whole network, you cannot only think of the location

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of one base station, instead, you should consider of the possibility of manyaddresses. Since the change of one address will affect the location of other basestations, the address selection of the base station should be based on a certainprinciple. After the address has been selected, the real station type will be definedaccording to the traffic distribution and the channel number of the base station.

V. Parameter Design of the Base Station Engineering

Decide the height of antenna hanging position according to the different coveragearea types, network structures and average height of the buildings. As to the basestation moving, the necessity of height adjustment of the antenna is decidedaccording to the network construction condition, objects required by subscribers tocover and the installation environment. In some mountainous area, because of thelandform, the base station has to be constructed on the mountain, it's better to selectthe directional antenna or the omnidirectional antenna with an electric declinationangle, and avoid the blind under tower.

The base station antennas are divided into two types, omnidirectional and directionalantenna based on the horizontal direction. In the vertical plane, all antennas have

directions. Generally the gain of the omnidirectional antenna is 6dBd~9dBd; the gainof the directional antenna is 9dBd~16dBd. The gain of the directional antenna refersto the gain in the maximum transmission direction. Generally, the omnidirectionalbase station is constructed only in the villages on the plain or some special landform,while the directional antenna is used in the base station of other areas on the whole.In the subscriber density cities, the common base stations (excluding the microcelland indoor distributed antenna system) are installed with the directional antenna atthe angle of 65 degree. In order to avoid the antenna interference, the antenna gaindoesnt need to be too high. The base station, with a few centralized subscribers andneeding a wide coverage, generally applies the directional antenna with high gain.The antenna direction angle and the declination angle (electronic declination ormechanical declination) should be designed reasonably.

In order to guarantee the normality of the network structure design and avoid theinterference as much as possible, the antennas of each sector in each base station ofthe local area is recommended to have the same direction, for example designed as0/120/240 or 30/150/270. While the antenna direction needs to be adjusted inthe base stations close to the sea, along the river, transport artery and the city-suburbcombination, areas with uneven traffic and center of city with many high buildings.Whats need highlighting is that because there are high buildings along many streetsin cities in different size, the base station cell antennas nearby cannot be installedwith an azimuth angle facing the street in order to avoid the wave-guide effect.

The antenna declination angle should be decided according to the special conditionson the premise of reducing the interference to the co-channel cell and covering thewhole coverage area without unnecessary blind area; when it declines too much, theratio emission in front of and behind the antenna must be considered, avoiding the

back lobe interfering the cell behind or the side lobe interfering the neighbor sector.Generally speaking, design a rather big declination angle for the cells near to thewater surface to avoid the interference to the opposite side of the water; the obliquityof 3~6 degree for the dense city center; no declination for the suburb and artery cell inorder to widen the coverage area.

In addition, the suitable feeder line, combiner and the tower amplification unit shouldbe selected according to the special conditions.

VI. Coverage Prediction

The coverage prediction is to predict the coverage of the network to be constructed,according to the address selected and the type designed, and to see if it can meet thedemand of the subscribers. The coverage can be predicted with the help of the

ASSET Network Planning Tools to select a map with a suitable accuracy. Thecoverage area of a base station mainly concerns the following factors: service quality

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index; transmitter output power; available sensibility of the receiver; the direction andgain of the antenna; frequency band applied; emission environment (landform, cityconstruction and other man-made environment); application of the diversity reception.

In case the result of the network coverage prediction cannot meet the requirements,the adjustment should be done. The usual measures include:

(1) When there are subscribers outside the cell coverage area, where is noteconomical to construct a site, broadcast station can be applied to solved theproblem. When the signal in the coverage area is weak or there is blind area in it, themicrocell can be considered to solve the problem according to the conditions.

(2) If the cell coverage areas dont overlap one another enough, it should beconsidered to increase the height of the antenna position or the number of the basestation according to the cell splitting principle.

(3) When the cell coverage area cannot hit the co-channel reference index, makeadjustment as follow:

Adjust the cell channel configuration;

Adjust the station address or other design parameters (including theantenna type, height of position, azimuth angle, the declination angleand transmission power). Accordingly the effects between the basestations need considering.

VII. Frequency Planning

The frequency re-use pattern is one of the important factors to be considered in thecell system planning. The frequency re-use refers to the application of the wirelesschannels at the same frequency in the cells of different coverage areas. The cells offrequency re-use should have a certain interval between each other to meet therequirement of the adjacent frequency carrier-to-interference ratio. The re-usedegrees of the same frequency are different in the different re-use patterns. Differentfrequency re-use patterns are applied in areas of different types. In a certain area, on

the promise of enough coverage, the number of the base station (cell) is decided bythe frequency planning pattern. Generally speaking:

(1) In the big and middle-sized cities, different aggressive frequency re-use patterns,like MRP, 13, etc., are applied according to the different equipment functions. At thesame time, reserve part of the frequency band for the microcell to construct layerednetwork. Its frequency re-use coefficient is rather small.

(2) In the small and middle-sized cities, different aggressive frequency re-usepatterns, are applied according to the different equipment functions. Whether itsnecessary to construct the layered network depends on the real condition. Itsfrequency re-use coefficient is a little bigger than that of the big and middle-sizedcities.

(3) In the towns and villages, which are rich in the resources, the standard 43frequency re-use pattern can be applied. The stations, constructed on the mountainsfor some geographic reasons, can be allocated some independent frequency bands.

At the pre-planning stage, the planners should present the application for thefrequency resource according to the scale and frequency planning pattern of thewireless network.

VIII. LAC Planning

LAC is also an important resource. At the pre-planning stage, the planners shouldpresent the initial allocation and resource application of the LAC based on theconsideration of network structure and scale.

IX. Cell Data Making

In order to guarantee the good and stable running of the network, its also necessary

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to configure the relevant data for each base station cell. What has to be highlighted is:the cell attribute parameters, cell handover band selection, channel allocationalgorism selection, turn on which handover algorism, and whether to use thefunctions, like frequency hopping, power control and DTX, should have been decidedin the above base station design, coverage prediction and frequency planning. In the

GSM system of Huawei, as to the detailed data design and configuration, please readthe Data Configuration Criterion of the GSM900, 1800 BSS network planning forreference.

1.2.4 Pre-planning Difficulties

As shown in the above progress, the pre-planning difficulties are reflected in thefollowing aspects:

(1) Complex emission environment, severely fluctuate signal, big difference of themulti-approach emission caused by the various man-made buildings, and thedifficulties in theoretic prediction of the coverage area.

(2) Severe interference. Except for the human noises, all adjacent frequency

interference, intermodulation interference and other wireless interference should beconsidered and controlled in the permitted index during the engineering design.

(3) Limited frequency resources. Its getting more serious along with the bigincreasing of the subscriber.

(4) There are strict rules for the cell structure and the cell splitting behavior designedfor the frequency re-use. The station address planning can hardly be carried out inthe real project due to various reasons.

(5) The investment control is the technical and economical issue of the networkconstruction, which can be by no means ignored.

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Chapter1 Network Planning Overview

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