Tutorial 1 MENT5533 (02-1718) Ver 1. PDF

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FACULTY OF ELECTRONIC AND COMPUTER ENGINEERING UNIVERSITI TEKNIKAL MALAYSIA MELAKA Sem 02 Session 2017/2018 MENT 5533 – Wireless Broadband Communications TUTORIAL 1 1) Classify the following wireless communications: Walkie talkie, cordless, cellular, PCS, Paging, PMR, LMDS, WiLL, WPAN, Satellite If ...

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FACULTY OF ELECTRONIC AND COMPUTER ENGINEERING

UNIVERSITI TEKNIKAL MALAYSIA MELAKA Sem 02 Session 2017/2018 MENT 5533 – Wireless Broadband Communications TUTORIAL 1 1) Classify the following wireless communications: Walkie talkie, cordless, cellular, PCS, Paging, PMR, LMDS, WiLL, WPAN, Satellite If they can be classified as belonging to one (or more) of the following 4 groups Group 1 Group 2 Group 3 Group 4

: : : :

High power, wide area system Low power, local area system Low speed, wide area system High speed, local area system

2) For the following wireless communication services: SMS, WAP, GPRS,W-CDMA State the type of switching, data rate, generation and standard used 3) (a) If Pt = 10W, Gt = 10dB, Gr = 3dB and L = 1dB at 900MHz, compute the received power for the knife-edge geometry shown in Figure 1. Compare this value with the theoretical free space received power if an obstruction did not exist. What is the path loss due to diffraction for this case?

Pt = 10W Gt = 10dB

hobs = 400m Gr = 3dB

ht = 60m

hr = 5m d1 = 3km

d2 = 2km Figure 1

(b) If the geometry and all other system parameters remain exactly the same in (a), but the frequency is changed redo the problem for the case (i) f = 50MHz and (ii) f = 1900MHz

(c) If the received power at a reference distance d0 = 1km is equal to 1 microwatt, find the received powers at distance of 2km, 5km, 10km and 20km from the same transmitter for the following path

loss model: (1) free space; (2)  = 3; (3)  = 4; (4) two-ray ground reflection using the exact expression; and (5) extended Hata model for a large city environment. Assume f = 1800MHz, ht = 40m, hr = 3m, Gt = Gr = 0dB. Plot each of these models on the same graph over the range of 1km to 20km. Comment on the differences between these five models.

4) A BS of 30m height is operating at 900 MHz and transmits 20W power. The transmitter and receiver antenna gains are 6dB and 2dB respectively. A MS of 2m height is located at 5km from the BS. If other losses is 5dB and fading =6dB due to log-normal fading, compare the minimum power received by the MS in dBm if the following propagation models are used: (i) Free space propagation loss, FSPL (ii)

Plane earth propagation loss, PEPL

(iii)

log-distance with do=1km, =4 and PL(do)=FSPL, and

(iv)

diffraction model if an obstacle of 30m height is located at 2km from the BS

Comment on the practical minimum power received by the MS if an obstacle stated in (iv) exist.

5) Four received power measurement at MS were taken at distances of 100m, 200m, 1km and 5km from the BS as shown in the Table 1. Table 1 Distance from BS (m) 100 200 1000 5000

MS received power (dBm) 0 -15 -40 -90

Assuming that the path loss for the measurements follows the log-distance model with d0 = 100m, estimate: (i) The minimum mean square error (MMSE) for the path loss component, n, and the standard deviation about the mean value (ii) The power received by MS located at 3km from BS using the resulting propagation model (iii) The probability that MS received signal level at 3km will be greater than –75dBm and the percentage of area receiving that signal level.

6) You are given the task to design a 900-MHz based cellular system in a medium sized city with a coverage of at least 98.5% over an area of 2200 km2 using hexagon cells. After carried out some coverage measurement, you decide to choose Hata emperical path loss model as below for your coverage prediction:

Lp  69.55  26.16 log f  13.83 log hT  a(hR )  [44.9  6.55 log hT ] log d where 150 < f < 1500MHz, 30 < hT < 200m, 1 < d < 20km and a(hR) is the correction factor:

a(hR )  (1.1log f  0.7)hR  (1.56 log f  0.8)

where 1< hR < 10m The BS height is 30m and transmitting 20dBW (EIRP). In order to receive a good quality of signal, the RSSI at the MS must be at least –105 dBm at a height of 3m with antenna gain of 2dB. Other system losses are 2.6dB. If the MS noise figure, F=5dB, at an ambient temperature, To=290K and Boltzmann constant, k=1.38x10-23 J/K, determine (a) SNR at the MS (b) cell radius and nbr of cluster for N = 7

7) A wireless system base station (BS) transmits a 20 W signal from an antenna located 20 m above a flat earth. The BS has a gain of 6dBi and the system losses are 2 dB. A receiver is located in a delivery truck with an antenna at top the truck at 3 m above the ground. The receiving antenna gain is 2 dBi and the system operates at 1.2 GHz. (a) Find the received signal power when the truck is 20 km from the BS. Express your answer in decibels above a milliwatt. (Hint: Use the Flat Earth model as given below)

Pr (dB)  Pt (dB)  Gt (dB)  Gr (dB)  20log(hb )  Lsys  4  log(d (m)) (b) What would the received signal power be in the absence of ground reflections?

8) A MS using GSM900 service is moving at 32 km/hr. (i) Estimate the level crossing rate and average fading duration at –10dB threshold levels (ii) Compute the received carrier frequency as the MS is moving directly away from the BS toward East (Point A) and then turned to North-West (Point B) at 36 km/hr and 28 km/hr respectively. The distance from Point A and Point B to the BS is 5 km (iii) Calculate the r.m.s delay spread and 50% coherence bandwidth for the multipath profile as shown...