POWER ALLOCATION STRATEGIES FOR THE DOWNLINKIN A W-CDMA SYSTEM WITH SOFT AND SOFTER HANDOVER:

THE IMPACT ON CAPACITYW.-U. Pistelli, R. Verdone

CSITE-CNR/DEIS-University of Bologna, V.le Risorgimento 2, 40136 Bologna, Italy{upistelli,rverdone}@deis.unibo.it

Abstract - In this paper, the power allocation strategy in thedownlink of a WCDMA system is investigated, with the aim ofassessing the network capacity. It is known that the downlinkcapacity for a base is limited by the maximum transmit power,which is a common resource to be shared by all users; if oneuser requires a large fraction of the allowed transmit power,the overall capacity could be decreased: in the work hereinwe analyse the impact on the capacity of a power allocationstrategy which limits the maximum fraction of transmit powerper link.

A semi-analytical model is developed, considering a classi-cal propagation model and taking soft handover and a multi-service scenario into account. The results show cell capacityas a function of some interesting parameters, such as the cellradius and the number of bases included in the active set. Boththe cases of omni and sectorised cells are considered.Keywords - WCDMA, Soft Handover, Capacity, Radio Re-source Management.

I. INTRODUCTIONThe Network Capacity for WCDMA is limited by downlink

performance [1]. Since the downlink capacity for a base stationis limited by the maximum transmit power, which is a commonresource to be shared by all users, a mobile requiring a largefraction of this power could reduce the overall capacity. In thework herein we analyse the impact on the capacity of a powerallocation strategy which limits the maximum fraction of trans-mit power per user.

The majority of papers in the literature dealing with capac-ity evaluation for the downlink of WCDMA systems (i.e. [2]-[6]) only take a limit in the total transmit power from eachbase into account; only a few of them also consider a limita-tion on the power that can be transmitted to the single user,generally evaluating the impact of this constraint on the aver-age power transmitted to each mobile (see e.g. [7]). To theAuthors knowledge, no works in the literature explicitly treatthe impact on the downlink capacity of the strategy describedherein, in a scenario taking the user distribution, noise, inter-ference, propagation aspects, three-sectorial antennae and therole of soft and softer handover into account. In this paperwe introduce this power allocation strategy in a semi-analyticalmodel, which allows the evaluation of the impact on the down-link capacity. The case of mixed types of services (Voice andhigh speed Data, both with reference to the circuit switchednetwork) is considered in the model.

Generally, the models presented in other works introducesome approximation to reduce the simulative part, such as thedrop of the thermal noise terms (see [4] [5]) or the introductionof an intracell-to-intercell interference ratio, which is evaluated

This work is performed under contract with the Project Multimedialitafunded by CNR and MIUR (Italy) and un the framework of COST273.

separately (see [2] [3]). Our approach is to eliminate these ap-proximations and to proceed via simulation when a completeanalytical methodology cannot be applied. We consider a clas-sical propagation model and a multi-service scenario; soft andsofter handover techniques are also accounted for. A direct re-lation between the number of served users and the radius of thecell is provided and the capacity is also obtained as a functionof the number of bases included in the active set.

II. SCENARIO AND NOTATIONS

A 19 hexagonal cell scenario is considered, given by a cen-tral cell plus two surrounding rings, and a uniform mobile dis-tribution is assumed. One or three base transceiver stations(BTSs) are located in the centre of each cell, depending on theuse of omni or three-sectorial antennae; each BTS transmitsat the maximum power Pmax and full reuse (1/1) is consid-ered. Mobile terminals mount omnidirectional antennae. Per-fect fast power control is assumed; this allows the considerationof the same short-term average (over Rayleigh fading) signal-to-interference-plus-noise ratio Eb/I0 received by each mobileterminal. Log-normally distributed Shadowing is also consid-ered, whereas the effect of fast fading is assumed to be aver-aged out by fast power control. A snapshot analysis is carriedout (no users mobility).

The study is based on the central cell and its BTS, whichare referred to with the number 1, for the case with omnidirec-tional antennae. With sectorised antennae, the scenario takenas reference is shown in Figure 1, where all cells and sectors areunequivocally numerated. The reference BTS will be denotedas BTS11 (cell 1, sector 1, grey area in Fig 1.).

The variables listed below will be used in the model: R0, the distance of a vertex from the centre of the hexagonalcell, in km. N (Nsect), the maximum number of served users in a cell(sector). , the portion of downlink power allocated to traffic channels(1- is for broadcast channels). Shji, the shadowing sample for mobile i with respect to thejth base station. It is a Gaussian random variable with zeromean and variance 2, when expressed in dB. ji, the portion of total (dedicated both to traffic and broad-cast channels) transmitted power at BTSj dedicated to mobilei. h, the orthogonality factor (h=0 is the orthogonal case). , the AF (Activity Factor), i.e. the probability that a genericchannel is active. It is also denoted as VAF (Voice AF) as onlyvoice users will be considered in the numerical results.

Denoting as rji the distance between mobile i and BTSj , theaverage (over shadowing) received signal power in the position

0-7803-7589-0/02/$17.00 2002 IEEE PIMRC 2002

of mobile i coming from that base can be expressed as:

Srji =K Pmax(rji)n

(1)

where K and n are the coefficient and the propagation lawexponent, respectively. Taking lognormal shadowing into ac-count the received signal power for the same link is Srji Shji.

III. THE MODEL: OMNIDIRECTIONAL CASE

From the definitions written above, it is possible to establisha system constraint:

Ni=1

1i 1 (2)

It states that the total transmit power at BTS 1 (the observedone) cannot exceed the system parameter Pmax. A similar con-straint could be set for each BTS.

A. Allocation of power: no handoverConcerning the interference received by the generic mobile,

it can be seen as the sum of an intracell component, given bythe users belonging to cell 1, and an intercell component, dueto those users external to that cell. Then, denoting as W thechip rate, R the bit rate and N0 the noise spectral density, theEb/I0 ratio for a mobile i connected only to BTS1 (that is, notin soft handover) after despreading is

Eb

I0

nho

=W/R 1i Sh1iSr1i

(1 1i)hSh1iSr1i+JX

j=2

ShjiSrji+N0W

(3)

where J represents the number of BTSs in the scenario (19 inthis case) and 1i is the effective portion of power that BTS 1transmits to mobile i on the traffic channel.

In order to evaluate the maximum capacity, as usual in theliterature (see [2]- [6]) it is assumed that the received Eb/I0 foreach mobile terminal not in handover is equal to the requiredthreshold, [Eb/I0]th, for the expected performance. In speechservice at 8 Kbps the ETSI documentation for UMTS (see [8]-[10]) suggests to consider a maximum level for the bit errorrate BER = 103 , that requires [Eb/I0]th = 7.6dB.

From equation (3) and (1), posing (Eb/I0)nho = [Eb/I0]th,

Sect.2

Sect.3

Sect.11

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

1

Fig. 1. Reference scenario. Three-sectorial case.

the variable 1i can be carried out

1i = 1i_nho =

(h 1) +JX

j=1

Shji

Sh1i

r1i

rji

n

+N0W (r1i)

n

KPmaxSh1i

h+p

(4)where

p W/R[Eb/I0]th

(5)

B. Allocation of power: soft handoverFor a user in soft handover (SHO) connected to 2 BTSs

(for example, BTS1 and BTS2), the received signal is givenby Maximal Ratio Combining processing, then(

EbI0

)sho 2

=(EbI0

)nho link1

+(EbI0

)nho link2

(6)

with(EbI0

)nho link1

and(EbI0

)nho link2

given by expressionssimilar to the second member of equation (3).

To proceed in this analysis, we introduce the usual assump-tion ( [4]- [6]) that the BTS1 contribution to the received signalis equal to that of BTS 2 :(

EbI0

)nho link1

=(EbI0

)nho link2

=12

[EbI0

]th_sho

(7)

Therefore, in this case we set the right-hand term of equa-tion (3) equal to 12 [Eb/I0]th_sho. As a result, an expressionsimilar to equation (4) still holds, provided that the parameterp defined in (5) is replaced by:

psho W/R12 [Eb/I0]th sho

= p 2 [Eb/I0]th[Eb/I0]th sho

(8)

Now, it is convenient to introduce a diversity factor, , de-fined as

[EbI0

]th sho[

EbI0

]th

=1Gh

(9)

where all the variables are in linear unit and Gh is the gainintroduced by soft handover, which can be expressed, in dB, by

Gh[dB] =[EbI0

]th

[dB][EbI0

]th sho

[dB] (10)

Values for Gh are given in [1]; Gh normally takes values be-tween 1 and 1.6 (0-2 dB).

Consequently, the expression of 1i for a mobile i in SHOwith two BTSs (one is BTS1) can be written as:

1i = (2)1i sho =

(h 1) +JX

j=1

Shji

Sh1i

r1i

rji

n

+N0W (r1i)

n

KPmaxSh1i

h+2

p

(11)

By generalizing, in the case of mobile i connected to a num-ber, m, of BTSs, equation (11) becomes:

1i = (m)1i sho =

(h 1) +JX

j=1

Shji

Sh1i

r1i

rji

n

+N0Wrn1i

KPmaxSh1i

h+m

(m)

p

(12)where (m) is the diversity factor due to m received signals.

In general, the diversity factor decreases with m; however,the value change is not so sensible for m > 2 and for thisreason (m) = (m = 2) = will be assumed for m > 2.

C. CapacityThe above expressions for the fraction of power allocated

to a generic mobile requires knowledge of the user positionand the shadowing samples. These aspects are considered hereby means of a Monte Carlo simulation, with users uniformlydistributed over the scenario.

Two simple geometric criteria are adopted, in order to eval-uate which users belong to cell 1 (the considered one) and tochoose which users are in soft handover (see figure 2 as a ref-erence).

Fig. 2. Geometric criteria for handover choices.

First of all, the mobile terminals that are at a distance smallerthan R0 from the center of the cell are assumed to belong to it.

Moreover, if the user distance from the cell center is betweenR0(1int) andR0, the mobile is considered in SHO; int isa parameter used to select the soft handover users percentage.The number of users located inside cell 1 (and so belonging toit) that are in soft handover will be referred to as Nsho.

Other users external to cell 1 but also connected to BTS 1have to be taken into account, and Nsho ext will represent theirnumber. In particular, a parameter ext is introduced, so thatall mobiles external to cell 1 but distant from its edge less thenR0 ext (see figure 2) are considered connected to BTS1 too.Assuming that all mobile terminals in soft handover are con-nected to m base stations, the total number of links betweenthose located inside cell 1 and the other BTSs isNsho(m1).Since the users are uniformly distributed and being the closestBTSs in a number of 6, each of these bases can be consideredon the average connected to Nsho (m 1)/6 users located

in cell 1. Viceversa, in each neighboring cell there is, on theaverage, a number Nsho (m 1)/6 of users connected toBTS1, and multiplying this number by 6 (number of neigh-boring cells) the total number of links between cell 1 and theexternal users is found:

Nsho ext = Nsho (m 1) (13)Considering that the mobiles are uniformly distributed in thescenario, the previous condition is satisfied if the ratio betweenthe external and internal areas of soft handover is equal tom 1. This relation provides a constraint in the choice ofthe parameters int and ext. Indeed, fixing int, the valueof ext must satisfy this constraint. int is fixed in the numer-ical results in order to have 20% of users in SHO.

In order to take the possibility of multi-service transmissioninto account, another parameter, D, is introduced; it representsthe fraction of users experiencing data transmission.

Following these considerations, equation (2) can be rewrittenas follows

(1D)(NNsho)i=1

s1i nho s +D(NNsho)

i=1

d1i nho d+

+(1D)(Nsho+Nsho ext)

i=1

s1i sho s+

+D(Nsho+Nsho ext)

i=1

d1i sho d 1 (14)

where the subscript s is for speech and d is for data and the lasttwo sums take both internal and external users of cell 1 intoaccount. The expressions of the portion of power for speechand data transmission are formally equal and differ only forsome parameter values. By replacing them in (14) and by car-rying out Pmax, the fundamental equation of this work (in thecase of omnidirectional antennae) is obtained; it is shown onthe top of next page. The equality has been considered in ex-pression (14) because the aim of the model is to evaluate themaximum capacity of the system.

Now, equation (15) gives the power level needed to fulfil thequality requirements set by the N users. By fixing the powerlevel Pmax and numerically reversing expression (15), we getto the maximum capacity per cell, N , provided that the valuesof the parameters are fixed and the users positions and shadow-ing samples are given.

D. Power limitation on single linkThe aim of this section is to introduce a forced limitation to

the fraction of power that can be dedicated to each mobile. Inparticular, if a mobile i needs a portion of power 1i largerthan a fixed maximum threshold , the power transmitted to itis set to the threshold level (that is, (lim)1i min(1i,)).Obviously, in this case the mobile has to be considered in out-age, as its Eb/I0 will be less than the desired level; by varyingthe value of , a control in the fraction of mobiles in outage ispossible. Reducing the resources dedicated to these unluckyusers, a larger portion of power is available and a larger num-ber of users can be consequently served. The system capacity

Pmax =

N0W

K

2

6

6

6

6

6

4

(1D)(NNsho)X

i=1

(r1i)n

Sh1i

h+ps

s

+

D(NNsho)X

i=1

(r1i)n

Sh1i

h+pd

d

+

(1D)(Nsho+Nsho ext)X

i=1

(r1i)n

Sh1i

h+m

ps

s

+

D(Nsho+Nsho ext)X

i=1

(r1i)n

Sh1i

h+m

pd

d

3

7

7

7

7

7

5

1

2

6

6

6

6

6

4

s (1D)(NNsho)X

i=1

Ai

h+ps

s

+

d D(NNsho)X

i=1

Ai

h+pd

d

+

s (1D)(Nsho+Nsho ext)X

i=1

Ai

h+m

ps

s

+

d D(Nsho+Nsho ext)X

i=1

Ai

h+m

pd

d

3

7

7

7

7

7

5

(15)

Ai = (h 1) +Jj=1

ShjiSh1i

(r1irji

)n(16)

is increased at the expense of a fraction of users that are in out-age. So, by varying , a relation between the number of servedusers (capacity) and the outage probability is provided.

IV. EXTENSION OF THE MODEL: SECTORISED CELLSIn this section, the model is developed in the case of three-

sectorial antennae.Non-ideal sectorisation is considered, with an overlapping

angle 0 = 10 degrees. All the assumptions of the omnidi-rectional case are still valid, as concerns the propagation lawand all the parameters values. The analysis focuses on sector 1of cell 1 (the dashed section in figure 1), that will be referredto as 1-1. In figure 1 the interferers of this sector have beenmarked by horizontal lines. All cells have only one sector thatinterferes with the considered one, with the exception of cell17, that has 2 interferers but is not adjacent to cell 1. Since thecontribution of interference from each sector located in a cellof the second ring is small, the second interferer of cell 17 willbe not considered, in order to avoid useless complication in theformalism of the model. In the following, each interferer willbe referred to with the number of its cell.

From a geometrical point of view, the introduction of anoverlapping angle 0 extends the zone reached by the radia-tion of each BTS and thus it generates some peripheral regionsinside each sector in which a larger number of interferers areheard (this is an aspect analysed, i.e., in [11]). These regionsare quite small compared to the sector area and, moreover, con-sidering the irregularity of realistic scenarios, this kind of anal-ysis becomes artificial and not so significative. For these rea-sons, as concerns the overlapping areas, the unique contribu-tion that will be added in the interference evaluation is that ofthe intersecting sector.

Then, denoting by 11,i the portion of total transmittedpower at BTS11 devoted to mobile i, and calling Nsect thenumber of users served by that base, equations (1) and (2) haveto be rewritten as follows:

Sr11,i =K Pmax(r1i)n

(17)

Nsecti=1

11,i 1 (18)

Here we consider K = 3K.

Now, we can generalise the evaluations carried out in sub-sections (III-A), (III-B) and (III-C) to this case of sectorisedantennae, taking both soft and softer handover into account.For the sake of simplicity, here we only repeat the final results,as all steps are straightforward generalisation of those of theabove subsections.

Denoting by Nsofter (Nsofter ext) the number of users in-ternal (external) to the sector 1-1 that are in softer handover,and carrying out Pmax, the fundamental equation of the sec-torisation case is then provided; it is shown on the top of nextpage. Equation (19) is the corresponding expression of equa-tion (15) with three-sectorial antennae. In same way as what isexplained in section (III), by fixing the power level Pmax andnumerically reversing expression (19), the maximum capacityper sector, Nsect, can be evaluated, provided that the values ofthe parameters are given and the users positions and shadowingsamples are fixed via simulation.

The power allocation strategy described in section (III-D)will be investigated in the sectorized case too.

V. NUMERICAL RESULTS

Equations (15) and (19) provide two expressions of Pmax asa function of m, N and the distances rji, that are distributedin the interval ]0, R0(1 + ext)]. So, for a given distributionof mobiles in the scenario, fixing Pmax at a certain value, arelation between m, N and R0 is obtained both in the omni-directional and in the sectorial case.

In order to evaluate these relations, equations (15) and (19)have been introduced in a computer program and the secondmember of the equations has been computed for a growingnumber of users, starting from one. The largest number ofusers for whom the needed transmitted power does not ex-ceed the chosen value of Pmax represents the maximum ca-pacity of the cell (or of the sector) for the given values of mand R0, and for the considered distribution of mobiles in thescenario. Repeating for a very large number of mobile distri-butions and averaging the results, two graphs of N = N(R0)andN = Nsect(R0)withm as a parameter can be drawn. Evenif the algorithm we presented allows evaluations of the capacitywith mixed traffic scenarios (data, voice, etc.), in the followingthe numerical results are worked out taking only voice usersinto account, as we want to emphasise the role of the powerallocation strategy on the capacity.

Pmax =

N0W3K

(1D)NIP

i=1

(r1i)n

Sh11,i

(h+ pss )+

DNIP

i=1

(r1i)n

Sh11,i

h+pdd

+

(1D)NIIP

i=1

(r1i)n

Sh11,i

(h+m pss )+

DNIIP

i=1

(r1i)n

Sh11,i

h+mpdd

+

(1D)NIIIP

i=1

(r1i)n

Sh11,i

(h+ 2 pss )+

DNIIIP

i=1

(r1i)n

Sh11,i

h+ 2pdd

1

s(1D)NIP

i=1Ai

(h+ pss )+

dDNIP

i=1Ai

h+pdd

+s

(1D)NIIP

i=1Ai

(h+m pss )+

dDNIIP

i=1Ai

h+mpdd

+s

(1D)NIIIP

i=1Ai softer

(h+ 2 pss )+

dDNIIIP

i=1Ai softer

h+ 2pdd

(19)

Ai = (h 1) +Jj=1

ShjiSh11i

(r1irji

)n(20)

Ai softer = (h 1) +Jj=1

ShjiSh11i

(r1irji

)n+Sh12iSh11i

(21)

NI = N Nsho,NII = Nsho +Nsho ext,NIII = Nsofter +Nsofter ext (22)

We have set J = 19 cells; = 8dB; N0[dBmHz ] = 169;n = 3.76; K[dB] = 128.1 + 13 = 115.1; h = 0.4; s =0.5; = 0.8; W = 3.84Mcps; R = 8Kbps (speech) and thevoice users handover gain Gh[dB] = 1.5.

Figure 3 refers to the case of omnidirectional antennae. Notethat in this figure the number of served users N (and the sameis for Nsect in figure 4) refers to users that are completely satis-fied, so it represents a lower bound to the cell (sector) capacitythat would be obtained considering a certain outage probability.Besides, no call admission control has been introduced and sosome mobiles with an unlucky shadowing sample are served,deeply decreasing the available power and increasing the inter-ference levels for other links.

In figure 3, five curves of N(R0) are drawn, with m fixed,respectively, to 1, 2, 3, 4 and 5. As R0 grows, the decrease ofcapacity is evident. Moreover, the curves show that N takesthe largest value for m = 1 and a value slightly smaller form = 2, whereas for m > 2 the maximum number of servedusers drops as m grows. This means that the introduction ofsoft handover does not affect the capacity if the active set sizeis limited to two BTSs for each user, whereas connecting all themobiles in soft handover to three, four or more BTSs producesa larger and larger decrease in the number of served users. Thereason is that the diversity gain introduced by soft handoverbalances the increase of the interference produced by generat-ing two connections for each mobile in handover zone, but itcannot balance the increase in interference that is generated byhaving more than two BTSs in the active set of each user.

In figure 4 the case of three-sectorial antennae is consid-ered, with voice users only. The number of users that can beserved by the BTS of a sector is evaluated as a function of thecell radius. The considerations made about figure 3 are alsosuggested by figure 4. Moreover, by multiplying Nsect by 3(the number of sectors of a cell) and comparing the result toN shown in figure 3, it is possible to find the sectorization

gain Gsect, defined as the ratio 3Nsect/N . The obtained re-sults indicate Gsect ' 3 for m = 1 or 2 and R0 = 0.5 or2.5km whereas for larger R0 or m the gain increases. The rea-son is that a power Pmax fixed at 20Watt (in the conditionschosen) does not constitute a limit for the system if m = 1or 2 and R0 = 0.5 or 2.5km (so that, the system is onlyinterference-limited), whereas it limits the number of users thatcan be served for larger values of m or R0. We found that thesensitivity of the model to the parameter Gh is very high, andthis makes it impossible to draw more precise conclusions asto the exact value of Gsect. The figures we have shown referto Gh = 1.5dB and indicate a sectorization gain of 2.8 2.9,which is equal to those carried out in other works that can befound in literature [3][11].

Finally, in figures 5 and 6, the results provided by the in-troduction of a power limitation on single link are presentedin the cases of omnidirectional and three-sectorial antennae,respectively: the curves show the fraction of mobiles in out-age versus N and Nsect when varying , considering both thenon-handover and the soft handover case (with m = 2). Bydecreasing , the fraction of mobiles in outage grows, but alarger number of users can be served. This is an important re-sult of this work: a power allocation strategy which limits themaximum fraction of transmit power per user allows an out-standing increase in the system capacity, to the expense of afraction of users that are in outage. Just to give a numericalexample, if we want to increase the number of served users(sectorizated case, figure 6) from 105 to 150, the fraction ofmobiles in outage doubles (from 5% to 10% for m = 1, from6% to 12% for m = 2). Also note that the curves shown inboth figures are roughly represented by straight lines.

VI. CONCLUSIONS

A simple semi-analytical model for UMTS system analysisfrom the capacity point of view has been presented. The model

takes multi-service transmission effects into account, in partic-ular the simultaneous presence of voice and LCD data users.

A relation between the maximum number of users that canbe served and the cells radius has been obtained, and the num-ber of BTSs in users active set and the percentage of users indata transmission are parameters of the model.

The optimal number of base stations that should be con-nected to the users in handover zone has been roughly eval-uated, by considering the same number of connections for allthe mobiles. Two have been found as the optimal value.

Finally, the impact on the system performances of a powerlimitation on each single link has been studied and a compari-son between the omni-directional and the sectorization case hasbeen shown.

REFERENCES[1] H.Holma, A.Toskala WCDMA for UMTS - Radio Access For Third

Generation Mobile Communications, ed. J.WILEY 2000.[2] K.S.Gilhousen, I.M.Jacobs, R.Padovani, A.J.Viterbi, L.A.Weaver,

C.E.Wheatley III, On the Capacity of a Cellular CDMA System,IEEE Transaction on Vehicular Technology, Vol.40, No.2, May 1991,pp.303-312.

[3] K.Sipila, Z.-C.Honkasalo, J.Laiho-Steffens, A.Wacker, Estimation ofCapacity and Required Transmission Power of WCDMA DownlinkBased on a Downlink Pole Equation, IEEE Vehicular TechnologyConference Proceedings, Tokyo, Japan, May 2000, pp.1002-1005.

[4] Q.Zhang, UMTS Air Interface Voice/Data Capacity - Part 2: ForwardLink Analysis, IEEE Vehicular Technology Conference, Vol.4, May2001, pp.2730-2734.

[5] W.Choi, J.Y.Kim, Forward-Link Capacity of a DS/CDMA Systemwith Mixed Multirate Sources, IEEE Transaction on Vehicular Tech-nology, Vol.50, Issue 3, May 2001, pp.737-749.

[6] A.De Hoz, C.Cordier, W-CDMA downlink performance analysis,IEEE Vehicular Technology Conference, Vol.2, Sept 1999, pp.968-972.

[7] P.Marinier, S.Aridhi, V.Roy, J.-L.Gauvreau, V.Sampath, M.Poirier,Performance Impact of Limited Downlink Dynamic Range of PowerControl on 3G WCDMA, IEEE Vehicular Technology ConferenceProceedings, Tokyo, Japan, May 2000, pp.2413-2417.

[8] Tdoc SMG2 905/97 - Concept Group Alpha: Evaluation Document(3.0), ETSI SMG#24, Madrid, 1997.

[9] Tdoc SMG2 351/98 - RTT Revision - Performance Results, ETSISMG#27, Marseille, 1998.

[10] 3GPP TSG RAN WG1/WG4 - Technical Specifications Series 2.5,October 1999.

[11] C.-C.Lee, R.Steele, Effect of Soft and Softer Handoffs on CDMA Sys-tem Capacity, IEEE Trans. On Vehicular Technology, Vol.47, Issue 3,Aug 1998, pp.830-841.

0 2.5 5 7.5 10 12.56

8

10

12

14

16

18

20

22

24

26

Cell Radius (R0[km])

Num

ber o

f ser

ved

user

s per

cel

l (N)

m=1m=2m=3m=4m=5

Fig. 3. Omnidirectional antennae. Number of served users per cell (N ) versuscell radius (R0), for 1, 2, 3, 4, 5 BTSs in the active set.

0 2.5 5 7.5 10 12.56

8

10

12

14

16

18

20

22

24

26

Cell Radius (R0[km])

Num

ber o

f ser

ved

user

s per

sect

or (N

sect

)

m=1m=2m=3m=4m=5

Fig. 4. Three-sectorial cells. Number of served users per sector (Nsect) vscell radius (R0), for 1, 2, 3, 4, 5 BTSs in the active set.

25 30 35 40 45 50 55 60 65 70 750.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0.2

Number of served users per cell

Frac

tion

of m

obile

s in

outa

ge

m=1m=2

Fig. 5. Fraction of mobiles in outage vs number of served users per cell, form=1 and 2. Omnidirectional antennae.

75 90 105 120 135 150 165 180 195 210 2250.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0.2

Number of served users per cell

Frac

tion

of m

obile

s in

outa

ge

m=1m=2

Fig. 6. Fraction of mobiles in outage vs number of served users per cell, form=1 and 2. Three-sectorial antennae.

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TutorialsSessionsMonday, 16 September, 2002MPO1.1-Radio Resource Management IMPO1.2-Turbo Coding IMPO1.3-4G SystemsMPO1.4-Space Time Coding IMPO1.5-Software Radio IMPO1.6-Wireless Propagation IMPO1.7-Wireless LAN IMPPo-Poster Session AMPO2.1-Radio Coverage & PlanningMPO2.2-Radio Resource Management IIMPO2.3-Turbo Coding IIMPO2.4-Multiple Access Techniques IMPO2.5-Space Time Coding IIMPO2.6-Software Radio IIMPO2.7-Wireless Propagation IIMPO2.8-Wireless LAN II

Tuesday, 17 September, 2002TAO1.1-Wireless IP ITAO1.2-OFDM ITAO1.3-MIMO Systems ITAO1.4-Multiple Access Techniques IITAO1.5-Wireless Propagation IIITAO1.6-Radio Resource Management IIITAO1.7-Space Time Coding IIITAO1.8-Wireless LAN IIITAPo-Poster Session BTAO2.1-OFDM IITAO2.2-MIMO Systems IITAO2.3-Multiple Access Techniques IIITAO2.4-Indoor PropagationTAO2.5-Radio Resource Management IVTAO2.6-CodingTAO2.7-Wireless IP IITPO1.1-OFDM IIITPO1.2-MIMO Systems IIITPO1.3-BRAIN / MINDTPO1.4-HSDPATPO1.5-Power Control ITPO1.6-Equalization ITPO1.7-Wireless IP IIITPPo-Poster Session CTPO2.1-Multi-User DetectionTPO2.2-OFDM IVTPO2.3-MIMO Systems IVTPO2.4-UMTS PerformanceTPO2.5-Satellite NetworksTPO2.6-Power Control IITPO2.7-Equalization IITPO2.8-Wireless IP / ATM

Wednesday, 18 September, 2002WAO1.1-OFDM VWAO1.2-Smart Antennas IWAO1.3-Spread Spectrum Receivers IWAO1.4-UMTSWAO1.5-High Altitude PlatformsWAO1.6-Power Control IIIWAO1.7-MIMO Channels IWAO1.8-Novel NetworksWAPo-Poster Session DWAO2.1-Smart Antennas IIWAO2.2-Spread Spectrum Receivers IIWAO2.3-CDMA 2000WAO2.4-Antennas & RF SubsystemsWAO2.5-QoS in RRMWAO2.6-MIMO Channels IIWAO2.7-Mobile ComputingWPO1.1-Smart Antennas IIIWPO1.2-Interference CancellationWPO1.3-GPRS / UMTSWPO1.4-Modulation TechniquesWPO1.5-Detection & Diversity TechniquesWPO1.6-TDD SystemsWPO1.7-Mobile InternetWPPo-Poster Session EWPO2.1-Experiments & DeploymentWPO2.2-Smart Antennas IVWPO2.3-Spread Spectrum TechniquesWPO2.4-Applications & ServicesWPO2.5-RF & BBWPO2.6-Packet ServicesWPO2.7-Network ProtocolsWPO2.8-Mobile Multimedia

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