3g system planing and optimization

TECHNICAL PAPER

Title: UMTS Radio Interface System Planning and Optimization Authors: Esmael Dinan; Aleksey Kurochkin; Sam Kettani; Telecomm & Industrial Date: December 2002 Publication/Venue: Bechtel Telecommunications Technical Journal Reprinted with permission

GGSN: Gateway GPRS Support NodeHLR: Home Location RegisterMSC: Mobile Switching Center

PLMN: Public Land Mobile NetworkRNC: Radio Network ControllerRNS: Radio Network S ubsystem

SGSN: S ervice GP RS Support NodeUTRAN: UMTS Terrestrial Radio Access NetworkVLR: Visited Loca tion Registe r

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The goal of the UMTS (universal mobile telecommuni-cations system) is to deliver multimedia services to

the user in the mobile domain. UMTS and multimediaservices have a significant impact not only on the RF(radio frequency) network, but also on the core networkarchitecture. Care must be taken to allow current GSM(global system mobile) operators to protect their infra-structure investments when their networks are upgradedto support UMTS.

The UMTS network architecture is depicted in Figure 1.The core network handles call control and mobility man-

agement functionalities, while the UTRAN (UMTS terres-trial radio access network) manages the radio packettransmission and resource management.

Packet routing and transfer within the core networkare supported by definition of new logical network nodescalled GGSN (gateway GPRS [general packet radio sys-tem] support node) and SGSN (serving GPRS supportnode). The GGSN is basically a packet router with addi-tional mobility management features, and it connectswith various network elements through standardizedinterfaces. The GGSN acts as a physical interface to theexternal packet data networks (e.g., the Internet). TheSGSN handles packet delivery to and from mobile termi-

December 2002 • Volume 1, Number 1 1

UMTS Radio InterfaceSystem Planning and Optimization

Esmael [email protected]

Aleksey [email protected]

Sam [email protected]

Issue Date: December 2002

Figure 1. UMTS Network Architecture

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nals. Each SGSN is responsible for delivering packets tothe terminals within its service area. GGSN and SGSN arecapable of supporting terminal data rates up to 2 Mbps.

A UTRAN consists of one or more RNSs (radio networksubsystems), which in turn consist of base stations(Node Bs) and RNCs (radio network controllers). The RNSperforms all of the radio resource and air interface man-agement functionalities. The UMTS network architectureinherits most of its structure from the GSM model in theUTRAN.

This paper focuses on the differences between GSMradio system planning and UMTS radio system planning.UMTS uses WCDMA (wideband code division multipleaccess) as the radio transmission technology. It isclaimed that TDMA (time division multiple access) RFplanning is much more difficult than CDMA-based sys-tems. This is true, in part, because of the interferenceissues. However, UMTS serves users with variousdemands, and many aspects of planning are more close-ly interrelated to each other in UMTS planning than theyare in GSM planning.

The major differences in the UMTS radio system plan-ning process occur in coverage and capacity planning. InGSM, coverage is planned separately after the network isdimensioned (based on the market study), and capacityand frequency are planned in tandem. In UMTS, coverageand capacity are planned at the same time, becausecapacity requirements and traffic distribution influencecoverage. Frequency and code can be planned separate-ly. On the other hand, the wideband nature of WCDMAtechnology (5 MHz) compared with GSM (200 kHz)imposes new criteria in modeling the propagation envi-ronments.

This paper outlines the challenges and solutions forplanning and optimizing UMTS networks with respect toradio interface. WCDMA air interface specifications andtheir implications on transmission channel behavior andmodeling are described first. Next, solutions are providedfor system design, including coverage, capacity, code,and frequency planning. The analysis captures bothdesign processes and engineering calculations. The criti-cal optimization and monitoring of WCDMA network per-formance are then discussed. Finally, the paper con-cludes by summarizing the results and presenting thefuture roadmap.

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WCDMA has been selected as the radio interfacetechnology of UMTS networks for much of the world.

It is totally different from the technology used in GSM orTDMA. The basic radio system planning philosophy usedin GSM or TDMA does not change, but almost all of thedetailed planning items concerned (e.g., the link budget)have to be checked and adjusted to be suitable forWCDMA technology. In addition, the radio system plan-ning process has to be modified slightly from the tradi-tional model because the traffic can vary from 8 kbpsvoice to 2 Mbps data and can be either circuit switchedor packet switched.

WCDMA Air Interface SpecificationsIt is important to understand the basic UMTS air inter-

face features to plan radio interface of the network. TheWCDMA specification has certain key features, which arelisted in Table 1.

Bechtel Telecommunications Technical Journal 2

Figure 2. Spectrum of Two WCDMA Carriers with 5 MHz Channel Spacing(Unlike GSM and TDMA, the same carriers can be used in all of the cells. Thus, the reuse factor for this

system is N = 1, while the GSM reuse factor is typically N = 4.)

WCDMA air interface is based on DS-CDMA (directsequence CDMA) technology. The user data sequence ismultiplied with a so-called spreading sequence, whosesymbol or chip rate is much higher than the user datarate. This spreads the user data signal to a wider fre-quency band. The relation between user data rate andchip rate is called a spreading factor (SPF = Rchip/Rbit).The chip rate in WCDMA is 3.84 Mchip/s, and spreadingfactors are in the range of 4 to 512; therefore, the usernet bit rates supported by one code channel are in therange of 1 to 936 kbps in the downlink. Up to three par-allel codes can be used for one user, giving bit rates upto 2.3 Mbps. In the uplink, data rates are half of these fig-ures, because of modulation differences.

The WCDMA standard includes two modes of opera-tion: WCDMA/TDD (time division duplexing) andWCDMA/FDD (frequency division duplexing). In WCDMA/FDD, the uplink and downlink signals are at different fre-quency bands. In WCDMA/TDD, the uplink and downlinksignals are at the same frequency but are separated todifferent time periods. WCDMA/FDD will probably be theair interface deployed and used first.

The nominal channel bandwidth of the WCDMA signalis 5 MHz. The specification provides the flexibility todefine the exact channel center frequency of 200 KHzraster, so the actual channel separation might be small-er than the nominal 5 MHz, down to the specified mini-mum of 4.4 MHz. This has to be noted carefully becauseit might cause interference in the network. An example ofthe spectrum of WCDMA for two carrier frequencies isshown in Figure 2.

The WCDMA transmission is split into 10 ms radioframes, each of which consists of 15 pieces of 666 ms(2560 chips) time slots. The bit rate and, for example,channel coding can be changed in every 10-ms frame,offering very flexible control of the user data rate. Everytime slot has bits reserved for pilot signal, power control(TPC bits), transport format indication (TFCI bits), and, ifnecessary, closed loop transmit diversity (FBI bits). Theexact signal format and multiplexing are quite different inuplink and downlink signaling. Also, the dedicated andshared channels have several differences in signal format.

UMTS Propagation EnvironmentThe radio propagation channel environment is divided

into outdoor and indoor classes. The outdoor class is fur-ther divided into macrocellular and microcellular propa-

gation environments. The macrocellular type of environ-ment can contain different building densities (e.g., urban,suburban, or rural). Each of these propagation environ-ments has special radio propagation channel character-istics. When considering the differences among GSM,TDMA, and UMTS radio interface performances, the keychannel property is the delay spread, which describesthe amount of multipath propagation in the propagationenvironment of the radio link. The delay spread can becalculated from the typical (estimated or measured)power delay profile, which describes the signal power asa function of the delay.

The effect of multipath on the radio channel can alsobe described by the frequency domain properties of theradio channel. In the frequency domain, multipath caus-es frequency selective fading, i.e., signals at different fre-quencies have different fading (amplitude and phase).One frequency domain property of the channel is coher-ence bandwidth, Dfc. It can be calculated from the timedomain property of delay spread. Coherence bandwidthis the minimum frequency separation of the two carriersthat have significantly uncorrelated fading. Table 2shows the calculated coherence bandwidths typical fordifferent radio propagation environments. The system isNB (narrowband) when the radio signal bandwidth ismuch smaller than the coherence bandwidth of the radiochannel and WB (wideband) when it is much larger.Therefore, that system property is dependent on the typ-ical propagation environment in which the system is usedand could differ in different environments.

The coherence bandwidth is related to the correlationof fading over the transmission bandwidth. In a propaga-tion environment where a system is narrowband, fadingis frequency nonselective or flat. In the wideband envi-ronment, fading for signal frequencies is uncorrelatedand the fading is called frequency selective. Comparingthe chip duration (0.26 ms) of WCDMA to the typicalurban channel delay spread, it can be seen that the delayspread is larger than the chip duration. A WCDMA receiv-er achieves optimum performance by using all of the mul-tipath components via a Rake receiver. The Rake receiv-er receives and combines different multipath delayedelements of the received signal. This combining methodis an advantage of WCDMA compared with GSM andTDMA signals and increases the received signal power.


Table 1. WCDMA Air Interface Specifications

Table 2. Characteristics of GSM versus UMTS forDifferent Radio Propagation Environments

Parameter Value

Modulation DS-CDMA with QPSK

Chip Rate 3.84 Mchip/s

Duplexing FDD and TDD modes

Channel Bandwidth 5 MHz with center frequencyraster of 200 KHz

Service Multi-rate and multi-service

Frame Length 10 ms frame with 15 time slots

Delay, µs ∆∆fc, MHz WCDMA GSM

Bandwidth BW=5 BW=0.2 MHz MHz

Urban 0.5 0.32 WB NB/WB

Rural 0.1 1.6 WB NB

Hilly 3 0.053 WB WB

Microcellular < 0.1 > 1.6 NB/WB NB

Indoor < 0.01 > 16 NB NB

Optimization and Monitoring

•- Traffic- Area- Coverage threshold

•- Traffic- Site configuration- Coverage thresholds &capacity requirements

•• Dimensioning • Detailed Planning •

- Traffic- Coverage verification- Capacity availability

Optimization and Monitoring

•- Traffic- Area- Coverage threshold

•- Traffic- Site configuration- Coverage thresholds &capacity requirements

•• Dimensioning • Detailed Planning •

- Traffic- Coverage verification- Capacity availability

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The implementation strategy must be planned careful-ly because UMTS is a totally new system. UMTS oper-

ates in the frequency band of 2100 MHz, which is muchhigher than the 900 MHz and 1900 MHz typically used inGSM and TDMA systems. Also, the higher data rates forUMTS require better signal strength, Eb/No. These oper-ating frequency differences, plus the higher data rates,mean that the radio propagation will not be equivalent.As a result, the old base station coverage areas are notnecessarily valid in UMTS. Although reusing the old basestation sites would be very cost-effective, they are notnecessarily the most optimum locations for UMTS cover-age. The decision to reuse the base station sitesdepends heavily on the implementation strategy and onthe traffic forecasts.

UMTS Radio System Planning ProcessThe UMTS radio system planning process is similar to

the GSM planning process. The phases of the planningprocess are:

• Dimensioning• Configuration planning• Coverage and capacity planning• Code and frequency planning• Parameter planning• Optimization and monitoring

The overall planning goal in any wireless system is tomaximize coverage and capacity while meeting the KPIs(key performance indicators) and QoS (quality of service).Figure 3 shows the UMTS planning process. In particular,the figure shows the one key issue in UMTS coverage andcapacity planning, namely that the traffic level has to beconsidered continuously in UMTS radio planning.

The distribution of the traffic levels between voice anddifferent data calls at each base station coverage areashould be determined as accurately as possible. Also, thelocation of the different mobile users (or actually the linkbudget of each mobile user) should be known as exactlyas possible. It is, of course, impossible to know themobile user locations exactly; however, the more accu-rately they can be forecast, the better the radio networkcan be designed.

Another key issue in WCDMA radio coverage andcapacity planning is the regional traffic distribution, orthe existence of traffic hot spots in the radio network cov-erage area. Base station locations should be selected sothat they are always placed on the traffic hot spots, sincethis offers the best link budget for the mobile usersserved by those base stations. As the users move awayfrom the base station, WCDMA throughput decreases. Asshown in Figure 4, placing base stations on traffic hotspots significantly reduces power levels in the radio net-work, which reduces interference and increases capacity.

In the initial dimensioning phase, a fixed load isassumed for all base stations within the targeted area.The value for the load can be the maximum acceptableload for the cells or it can be the predicted load duringthe busy hour. If the highest acceptable load is used, thedimensioning is done according to the worst-case sce-nario, which may lead to an unnecessarily high number ofsites. It is better to use the predicted load, because it willgive more realistic results.

In the detailed planning phase, the traffic distributionis used to allocate the predicted traffic to the plannedcells. This may lead to situations in which the loadbetween the cells can vary remarkably. Some cells mayhave a load very close to the maximum acceptable load,and some cells may have a fairly low load. Coverage tar-gets must also be checked during this planning phase.


Figure 3. UMTS System Planning Process

Hot Spot Hot Spot

HotSpot

HotSpot

a) Lower coverage and capacity (inefficient design)

b) Higher coverage and capacity (optimum design)

Hot Spot Hot Spot

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b) Higher coverage and capacity (optimum design)

Although, in dimensioning, the traffic is assumed to beevenly distributed across a particular area, in reality,each area may have a different traffic density. Also, indimensioning, propagation is assumed to be similar forall cells and all cells are assumed to be identical. Duringdetailed planning, coverage predictions can be quite dif-ferent among the cells due to propagation environmentand traffic distribution. Typically, Monte-Carlo distributionof the mobile stations is used to predict instant trafficdemand in the area of interest.

WCDMA Transmitter, Receiver, and Channel Parameters

WCDMA coverage planning begins from the link budg-et calculation. The link budget in WCDMA, as in GSM,takes into account the base station equipment configu-ration and the base station antenna line configuration.The WCDMA link budget also contains some new param-eters that are not used in the GSM link budget. A typicallink budget for WCDMA is presented in Table 3. The linkbudget is calculated based on the following assumptions:

• Uplink bit rate is 64 kbps and downlink bit rate is144 kbps.

• Predicted load in uplink is 30 percent and in down-link, 50 percent.

• 1 W output power at the BTS is reserved for a con-nection.

The link budget in Table 3 is divided into five parts. Ingeneral information, the frequency band, chip rate, tem-perature and Boltzman's constant are given. In serviceinformation, the bit rates and loads for uplink and down-link are defined. Receiving end and transmitting enddefine the radio links in the uplink and downlink direc-tions, respectively. Finally, isotropic path loss is defined

as the maximum expected path loss between the receiv-er and transmitter.

WCDMA Coverage and Capacity Planning Coverage and capacity planning in WCDMA are inter-

related. In low traffic areas, WCDMA planning is quitesimilar to GSM planning, because the load does not havea great impact on coverage. Of course, many details dif-fer between the systems, but the main principles can beapplied to both. In high traffic areas, unlike for GSM,there is no clear split between coverage, interference,and capacity planning of WCDMA.

Coverage PlanningThe propagation predictions for WCDMA require the

same planning phases as in GSM. First, the base stationconfiguration and the link budget have to be defined.Also, the coverage threshold has to be well defined toexceed the required quality criteria but avoid unneces-sary additional investments for the radio network ele-ments. Moreover, the capacity targets and forecasts haveto be well known at this phase because they have astrong effect on the base station coverage area. Whenthe base station antenna height, coverage threshold, andcapacity requirements are defined and the base stationconfiguration is clarified in the link budget calculations,the actual propagation predictions process can start.Propagation measurements can be performed to fine-tune the propagation prediction model. When the predic-tion model is tuned, the final base station parameterscan be used to make the propagation predictions.

Optimized base station parameters can be evaluatedwhen the planning criteria are defined. This planningthreshold means that agreement must be reached on thereasonable QoS level required for the different geograph-


Figure 4. Correct UMTS Base Station Placement Impacts System Capacity

General Information Units Value

Frequency MHz 2100Chip rate Mcps 3.84Temperature K 293Boltzman's constant J/K 1.38E-23

ical locations. The threshold also depends on whetherthe service has to be extended inside vehicles and build-ings in different areas. The planning threshold is definedin GSM by starting from the mobile station sensitivity (forthe forward link) and by adding the required clutter plan-ning margins to the sensitivity value in each particularplanning terrain bin.

Capacity PlanningWCDMA capacity planning is directly related to the link

budget and, thus, to the base station coverage area. Inthe link budget in Table 3, only one type of service(64/144 kbps data transmission) was introduced, andthe base station coverage was fixed for this service. It is

possible to have any type of service between the voicecalls and 2 Mbps data traffic in the WCDMA base station.This means that the base station coverage area is differ-ent for different users. (See Figure 5.) Basically, the ques-tion is about the spreading factor, SPF, which varies sig-nificantly when comparing the 12.2 kbps voice call (SPF = 25 dB) and 2 Mbps data transmission (PG = 2.8 dB)connections.

In the uplink direction, the main objective in capacityplanning is to limit interference from the other cells to anacceptable level. Network planning can increase theuplink load by reducing other cell interference. This canbe achieved by using buildings, hills, etc., as obstacles toblock the interfering cells. Also, down-tilting is a very use-


Table 3. Typical Link Budget for WCDMA Cell

Receiving End Units Uplink Downlink

Thermal noise density dBm/Hz -173.93 -173.93Receiver noise figure dB 3.00 6.00Receiver noise density dBm/Hz -170.93 -167.93Noise power dBm -105.09 -102.09Interference margin dB 1.55 3.01Receiver interference power dBm -108.77 -102.09Total noise (thermal + interference) dBm -103.54 -99.08Processing gain dB 17.78 14.26Required Eb/No dB 5.00 4.00Receiver sensitivity dBm -116.32 -109.34RX antenna gain dBi 18.00 0.00Cable loss dB 4.00 0.00LNA gain dB 0.00 0.00Antenna diversity gain dB 0.00 0.00Soft handover diversity gain dB 3.00 3.00Power control headroom dB 0.00 0.00Required signal power dBm -133.32 -112.34Field strength dBµV/m 10.32 31.31Z = 77.2 + 20*log(freq[MHz])

Transmitting End Units Uplink Downlink

TX power per connection W 0.126 1.00TX power dBm 21.00 30.00Cable loss dB 0.00 4.00TX antenna gain dBi 0.00 18.00Peak EIRP dBm 21.00 44.00Isotropic path loss dB 154.32 156.34

Service Information Units UrbanUplink Downlink

Load % 30 50Bit rate Kbps 64.0 144.0

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ful tool in limiting interference. In the downlink direction,two aspects should be considered: the interference fromother cells and the power of the base station. The loadequation for the downlink is similar to the equation forthe uplink. However, in the downlink there is a newparameter called orthogonality. Orthogonality is a meas-ure of how much the users in the same cell do not inter-fere with each other. In the downlink, users are muchmore orthogonal compared with uplink, because thebase station is transmitting to all the mobiles with veryaccurate timing of the spreading codes.

WCDMA Code and Frequency Planning In WCDMA, code and frequency planning are simple

tasks from a network planning point of view. The systemtakes care of most of the code allocation. The main taskfor network planning is the allocation of scramblingcodes for the downlink (Ref. 4). There are 512 sets ofscrambling codes available, so the code reuse for down-link is 512. This means that code allocation is a relative-ly simple task, even though code capacity does differ forevery user demand type. With more bandwidth userrequests, a higher-level scrambling code is needed fromthe hierarchy of codes, and more code resources aredrawn on.

It is recommended that the allocation be done with thehelp of a planning system to avoid the possibility for anerror in the manual allocation. The number of codes usedin the early stages should be limited to allow for easierexpansion of the network.

Frequency planning has minor importance comparedwith GSM. At most, UMTS operators have two or threecarriers, so there is not much to plan. However, the oper-ators have to make a few decisions:

• Which carrier(s) is used for macro cells?• Which carrier(s) is used for micro cells?• Is any carrier(s) reserved for indoor solutions?

When making these decisions, the interferenceaspects should be considered. Carrier selection mayaffect intra-operator and inter-operator interference. Forexample, micro cells can cause high local interference forthe operator's macro cells or another operator's macro ormicro cells. Many potential problems can be solved byproper network planning, and one of the techniques forsolving these problems is to properly select the frequencies.

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The WCDMA system, like the GSM system, needs con-tinuous optimization and monitoring because the

mobile users' locations and traffic behavior vary con-stantly. This monitoring requirement is emphasized inWCDMA, as in all CDMA systems, because the trafficdemand can vary widely and this variation directly influ-ences the radio network quality. The better and moreaccurately the traffic amount and locations can be mod-eled, the better and more efficiently (cost, quality, etc.)the radio network can be designed and implemented.

The indicators that should be optimized and moni-tored are, for example:

• Traffic• Traffic deviation• Traffic mixture• Soft handover percentage• Average TX power• Average RX power• Drop calls


Figure 5. Relative Cell Range and Cell Area versus User Bit Rate Using WCDMA(Cell ranges calculated by using Okumura-Hata propagation formula [Ref. 3] and antenna height of 25 meters)

a) Unbalanced load b) Balanced load using smart antenna

Sector A

Sector B

Sector CSector A

Sector B

Sector C

Sector A

Sector B

Sector CSector A

Sector B

Sector C

Sector A

Sector B

Sector CSector A

Sector B

Sector C

• Interference• Handovers per cell• Inter-system handovers• Throughput• Bit error rate and frame error rate

Many of the listed indicators should be collected on acell and service basis, because the data may give hintson how to optimize the parameters to enhance the per-formance of the network. A detailed discussion of theWCDMA system is out of the scope of this paper.However, three particularly important optimization chal-lenges for WCDMA cell sites are examined: traffic loadbalancing, handoff overhead management, and interfer-ence control.

The fundamental problem of traffic loading is that cel-lular traffic is distributed unevenly among different geo-graphical areas of the network. In fact, even within cellstraffic tends to be distributed unevenly among the sec-tors. Such imbalance has the effect of locking up networkcapacity in underutilized sectors while causing blockingproblems in the most heavily used sectors. Balancing thetraffic load among the sectors of a cell alleviates theblocking and creates headroom for traffic growth. And bycreating headroom at network hot spots, a targeted traf-fic load-balancing strategy allows more traffic growth andmore efficient use of infrastructure and spectrum acrossthe entire network.

One way of achieving load balancing is to modify theantenna orientation and angular beamwidth of each sec-tor to unify the traffic. This is possible using smart arrayantennas, as shown in Figure 6.

Another aspect of WCDMA optimization that directlyaffects cell site capacity is the management of handoffoverhead. The soft/softer handoff feature of the CDMAair interface improves the quality and reliability of CDMAcalls. However, because a given mobile may be in contact

with two or more cells or sectors at any given time, as inareas A and B in Figure 7, soft/softer handoff implies asignificant cost in capacity. After measuring the pilotstrength in the area, the size of handoff zones within thecell footprint should be decreased. Handoff zones shouldbe shifted from high-traffic areas to low-traffic areas.

Interference directly limits capacity of CDMA cell sites.One of the biggest interference problems in WCDMA net-works is pilot pollution. Pilot pollution is often caused dueto high-elevation sites with RF coverage footprints muchlarger than normal. The solution is to reduce the size ofthe coverage footprint. This can be accomplished byreducing the elevation of offending antennas, introducingdowntilt, or reducing the transmitted power.


Figure 6. Balancing Traffic Load and Boosting Capacity Using Smart Antenna

A

B

A

B

Figure 7.Example of Inefficient Design, Where a Large Area is

Covered by Soft/Softer Handoff

CCOONNCCLLUUSSIIOONNSS

The UMTS radio interface system planning has thesame basic philosophy as GSM but varies in the detail

mainly because of two reasons: the change of radiopropagation channel that is a wideband type, and thechange of modulation and transmission mechanism thatis DS-CDMA. The major subjects and findings are againgathered in Table 4 to summarize the major challengesconcerning radio interface system planning in UMTS.

RREEFFEERREENNCCEESS

1. T. Ojanpera and R. Prasad, "An Overview of Air InterfaceMultiple Access for IMT-2000/UMTS," IEEECommunications Magazine, September 1998, pp 82-95.

2. European Telecommunications Standards Institute,GPRS, GSM, EDGE, and UMTS Standard Documents,(http://www.etsi.org/getastandard/home.htm).

3. M. Hata, "Empirical Formula for Propagation Loss inLand Mobile Radio Services," IEEE Transactions onVehicular Technology, Vol VT-29, No. 3, August 1980, pp317-325.

4. E. Dinan and B. Jabbari, "Spreading Codes in DirectSequence CDMA and Wideband CDMA," IEEECommunications Magazine, September 1998, pp 48-54.

5. T. Ojanpera and R. Prasad, WCDMA: Towards IPMobility and Mobile Internet, Artech HousePublishers, 2000.

BBIIOOGGRRAAPPHHYY

As a senior RF engi-neer with Bechtel Tele-c o m m u n i c a t i o n s ,Esmael Dinan has beeninstrumental in manyaspects of the AWSLiberty RF engineeringproject and Bechtel GBU(Global Business Unit)research activities. Hisactivities include designof the RF engineeringdata management sys-tem, development of the

Liberty project RF engineering processes and proce-dures, Star21 Network auditing, and Dupont CryogenicTMA performance verification and testing.

Before joining Bechtel, Esmael was product managerfor GMPLS control plane of the RAYStar DWDM opticalswitch at Movaz Networks, and lead network architect atWorldcom.

Esmael has conducted research on access methodsand performance modeling of 3G wireless communica-tions and high-speed optical networks. He has authoredmore than 20 conference papers and journal articles andhas filed a patent on a novel signaling mechanism devel-oped for 3G cellular networks.

Esmael received his Ph.D. in Electrical Engineeringfrom George Mason University, Fairfax, VA.


Table 4. UMTS Radio Interface System Planning and Optimization

Subject Finding

WCDMA radio propagation channel • Channel delay spread is larger than chip duration; therefore, channel is wideband (frequency selective fading).

• Rake receiver takes into account multipath.

WCDMA coverage and • Coverage and capacity planning are related.capacity planning process • Code planning is unique to WCDMA systems, while channel

planning is unique to GSM.

• Traffic information and forecasting are necessary in coverage planning.

WCDMA link budget • Planning covers the same basics as GSM, but uses different parameters.The WCDMA link budget depends on changes in bit rate and spreading factor.

Capacity planning • Service depends on the distance from base station.

Frequency planning • A simple process: The same frequency can be used for all the cells.

Code planning • Allocation of scrambling codes is required for downlink.

Optimization and monitoring • These factors are of greater importance than with GSM.

Esmael Dinan

Aleksey Kurochkin iscurrently director, Wire-less Planning, in theBechtel Telecommunica-tions Technology group,a group that he originat-ed. Aleksey has experi-ence in internationalte lecommunicat ionsbusiness managementand network implemen-tation. Between engi-neering and marketingpositions, he has both

theoretical and hands-on experience with most wirelesstechnologies. Aleksey came to Bechtel from HughesNetwork Systems, where he built an efficient multi-productteam focused on RF planning and system engineering.

Aleksey is an electrical engineer, specializing intelecommunications and information systems, with anMSEE/CS degree from Moscow Technology University.

Sam Kettani is a sen-ior RF engineer atBechtel Telecommuni-cations. Currently, he isresponsible for networkdesign of mobile andfixed wireless networks.He has hands-on experi-ence with wireless tech-nologies and applica-tions such as PCS andTDMA/CDMA and networkperformance analysis,microwave design, and

engineering of fixed wireless networks using PTP (point-to-point) and PMP (point-to-multipoint) technologies. Inprevious positions, he was responsible for network plan-ning and integration of various systems. Sam was alsoresponsible for guidelines and processes, coordinatingand managing numerous projects.

Sam has a Bachelor of Science degree in ElectricalEngineering in Telecommunications from George MasonUniversity.


Aleksey Kurochkin

Sam Kettani