Cellular Network Planning and Optimization Part XII: Examples

Example problems Path loss can be given in a generic form(1)L=A+10⋅n⋅log10(R)Explain the meaning of parameters n and R.What is the interval [a,b] where n is expected tovary? Consider the Okumura-Hata model and computethe decrease in path loss when base stationantenna is increased by 5 meters. Carrierfrequency and mobile station antenna heightremain the same.( ) ( )L = A + B log f −13.82log h − a h + C − 6.55log h log d10 c 10 b m 10 b 104

Example problems Explain the following terms using few sentences co-channel interference adjacent channel interference5

Problem Let the SINR be given aswhere R is the cell range, D is the reusedistance (distance to nearest co-channel cell), Nis noise power and P is transmission power. For a given SINR requirement and path lossexponent, compute SNR on the cell edge fordifferent cluster sizes.6

Given figure13121110C(α)98762.5 3 3.5 4 4.5 5α7

Problem Use SINR model whereAssume that system is interference limited andnumber of given channels is 20, required SINRis 9dB and propagation exponent (path lossexponent) is 4. Compute the cluster size. Whatis the number of channels per cell?8

Problem Assume an antenna in which there are 6 λ/2dipoles on top of each other so that narrowvertical beam can be formed. What is antenna gain (in dBi’s) of an ideal panelantenna when horizontal 3dB beam width is 65degrees (3-sector site)?9

Example GSM 900 with 20 W output Losses and gains Combiner: -3 dB Diplexer -0.5 dB Feeder cable -2.5 dB Antenna gain +17 dBi Total +11 dB Effective Isotropic RadiatedPower (EIRP) EIRP = 43dBm + 11 dB =54dB (=251W)GSM900TRX/f1TRX/f2GSM1800CombinerFeeder cableDiplexer10

Assume thatProblem Operator has 5 MHz available for GSM Operator makes the TCH frequency plan according tospecifications (SINR > 9dB) but add 6dB marginal forBCCH SINR. Propagation exponent is 4, system is interferencelimited Problems What are the cluster sizes for BCCH and TCH? How many TRX’s are needed What is the number of TCH/F and TCH/H speechchannels per cell?11

Problem What is frequency hopping? Why it is used?Explain at least two gain mechanisms. What arecommon band strategy and dedicated bandstrategy for frequency hopping in GSM network?12

Problem Link budget calculation for GSM13

Problem What are the differences between WCDMAspreading and scrambling codes? For whatpurposes spreading and scrambling codes areused in WCDMA?14

Problem Name WCDMA QoS classes and give anexample application for each class. Name alsoQoS parameters.15

Problem Why Radio Resource Management (RRM) is soimportant for WCDMA? What are main RRMfunctions?16

Problem Explain briefly the purpose of the followingfunctions Fast power control (=transmit power control) in UL Outer loop power control in UL Soft handover in UL. What is difference between sof tand softer handover? Admission control Congestion control Packet scheduler17

Problem Explain briefly SHO reporting events 1a and 1band related reporting ranges. What happens inthe given figure (not explicitly stated in thisexample)? Why these parameters are importantin WCDMA network planning?18

Problem WCDMA UL/DL link budget calculation problem UL load equation problem DL load equation problem Deduce UL load equation Deduce DL transmission power needed in basestation Name all parameters in equations19

Problem Related to WCDMA link budget computationexplain briefly Fast fading margin (=power control headroom) Shadow fading margin Interference margin How WCDMA coverage and capacity areconnected?20

Problems Why correct antenna tilt is so important for WCDMA?Name two ways to implement the antenna tilt. What i sthe difference between methods?What is pilot pollution in WCDMA? How the so-calledactive set and pilot pollution are related? What ne tworkplanning and optimization means we have against pil otpollution in WCDMA? What are soft and softer handover in WCDMA? Explainboth uplink and downlink soft and softer handovers. Whysoft handover optimization is important in WCDMA?What is active set? What is monitored set (=neighbo urlist)21

Problems What are the main differences between WCDMAand HSDPA systems? What is Channel aware scheduling? Explainwhat multi-user diversity is. Draw a figure inorder to support your explanation. Explain hybrid automatic repeat request Explain adaptive modulation and coding22