Tutorial 8

Mohamed Esam

Mobile Communications

o

6

13

57

2

4

Omni Cell planning

6

13

57

2

4

120 Sectorization

63

57

2

41

60 Sectorization

o

810

1

7

2

3

4

9

6

12

5

11

Tricell planning: (Most (Most Common)Common)

No. of cells in the cluster can be divided by 3

Tricell planning

D1 D2D3

C3 C2C1

A3 A2A1

B3 B2B1 D1 D2

D3

C3 C2C1

A3 A2A1

B3 B2B1

D1 D2D3

C3 C2C1

A3 A2A1

B3 B2B1 D1 D2

D3

C3 C2C1

A3 A2A1

B3 B2B1

D1 D2D3

C3 C2C1

A3 A2A1

B3 B2B1

D1 D2D3

C3 C2C1

A3 A2A1

B3 B2B1

D1 D2D3

C3 C2C1

A3 A2A1

B3 B2B1

D1 D2D3

C3 C2C1

A3 A2A1

B3 B2B1

))/(3

1log(10/ RDIC

Prob.1 Construct 4 Walsh (Orthogonal) codes for 4

different users by two methods. Assume that 4 users transmit their data with 22Kbps (before spreading) using these codes such that:

User 1 transmits +1 @ 500m User 2 transmits -1 @ 1000m User 3 transmits -1 @ 1200m User 4 transmits -1 @ 1500m Carrier Freq.=3GHz Path Loss Factor=2.

a) For downlink transmission, Construct the transmitted and decoded (de-spread) signals for the 4 users. Assuming users 1,2,3&4 see the following attenuation L1X, L2X, L3X and L4X; where Li is the path loss factor with (n=2) plus the following Noise Level; U1: +0.5p, U2: -1p, U3: +0.5p, U4:+1p. Find the decoded signals and calculate the average bit error rate based on X. Given that 0<X<1.

c) X is the attenuation factor due to the shadowing effect with Standard deviation =32dB, Find the bit error rate (BER).

d) If X has Rayleigh Fading distribution instead of the shadowing effect, Find the bit error rate (BER).

e) Find the Average Duration of fade in Case (d) for 100km/hr vehicle.

L1L2

L3

L4

1-aW1=0 W2= 0 0 0 1

-1 -1 -1 -1-1 1 -1 1-1 -1 1 1-1 1 1 -1

-1 -1 -1 -1-1 1 -1 1-1 -1 1 1-1 1 1 -1

-1 -1 -1 -1-1 1 -1 1-1 -1 1 1-1 1 1 -1

1 1 1 11 -1 1 -11 1 -1 -11 -1 -1 1

W0=0000W1=0101W2=0011W3=0110

W4= 0 0 0 0 0 1 0 1 0 0 1 1 0 1 1 0

W8=

*L1*X

1-a Wireless Channel

U1

U2

U3

Data

Data

Data

U4

TransmittedSignal (Air)

-1 -1 -1 -1

-1 1 -1 1

-1 -1 1 1

1 1 1 1

-1 -1 -1 -1

-1 -1 -1 -1

-1 -1 -1 -1

-1 -1 -1 -1

1 -1 1 -1

1 1 -1 -1

1 -1 -1 1

2 -2 -2 -2

Transmitter

(2 -2 -2 -2)*L1*X

-1 1 1 -1

(2 -2 -2 -2)*L2*X

(2 -2 -2 -2)*L3*X

(2 -2 -2 -2)*L4*X

*L2*X

*L3*X

*L4*X

+0.5p

-1p

+0.5p

+1p

Added Noise@ Rx

(2 -2 -2 -2)*L1*X

(2 -2 -2 -2)*L2*X

(2 -2 -2 -2)*L3*X

(2 -2 -2 -2)*L4*X

(2L1X+0.5 -2L1X+0.5 -2L1X+0.5 -2L1X+0.5)

(2L2X-1 -2L2X-1 -2L2X-1 -2L2X-1)

-1 -1 -1 -1-1 -1 -1 -1

-1 1 -1 1-1 1 -1 1

-1 -1 1 1-1 -1 1 1

-1 1 1 -1-1 1 1 -1

(2L3X+0.5 -2L3X+0.5

-2L3X+0.5 -2L3X+0.5 )

(2L4X+1 -2L4X+1 -2L4X+1 -2L4X+1)

(-2L1X-0.5 +2L1X-0.5 +2L1X-0.5 +2L1X-0.5)

(-2L2X+1 -2L2X-1 +2L2X+1 -2L2X-1)

(-2L3X-0.5 +2L3X-0.5 -2L3X+0.5 -2L3X+0.5)

(-2L4X-1 -2L4X+1 -2L4X+1 +2L4X-1)

= +4L1X -2p “if ” >0 1

= -4L2X < 0 0

= -4L3X < 0 0

= -4L4X< 0 0

•L12=

pWattd

3.253))500*4)(10*3(

10*3()

)1*4(( 2

9

8

pWattd

3.63))1000*4)(10*3(

10*3()

)2*4(( 2

9

8

pWattd

9.43))1200*4)(10*3(

10*3()

)3*4(( 2

9

8

pWattd

14.28))1500*4)(10*3(

10*3()

)4*4(( 2

9

8

•L22=

•L3

2= •L4

2=

(-2L1X-0.5 +2L1X-0.5 +2L1X-0.5 +2L1X-0.5)

(-2L2X+1 -2L2X-1 +2L2X+1 -2L2X-1)

(-2L3X-0.5 +2L3X-0.5 -2L3X+0.5 -2L3X+0.5)

(-2L4X-1 -2L4X+1 -2L4X+1 +2L4X+1)

X is the attenuation factor due to the shadowing effect with Standard deviation =27.5dB, Find the bit error rate (BER).

= +4*253.3p X -2p if >0 1

= -4*63.3p X < 0 0

= -4*43.9p X < 0 0

= -4*28.14p X< 0 0

As 0<X (Attenuation) <1 is always positive;

= +4*253.3p X -2p (NOT always >0 User1 sent: 1)

= -4*63.3p X (always <0) User2 sent: 0

= -4*43.9p X (always <0) User3 sent: 0

= -4*28.14p X (always <0) User4 sent: 0

Probability of Correct decoding is:Probability that X > 1.974*(10^-3)So: Probability that Loss <1/( 1.974*(10^-3)) So: Power Loss < 1/( 1.974*(10^-3))^2 or Power Loss < 54 dB

b-

%1375.1011375.00455.0*25.0BER

0455.0)dB54X.(obPr

9545.0)dB54X.(obPr

6875.132

54Z

dBLL

Z omax

c-If Rayleigh Fading is Considered

instead of the shadowing effect,

1212

12)10(

/

10*425.0*10*848.15

10*848.151)54.(Pr

1).(Pr24.5

2min

2

BER

eXob

eOutageob rmsrr

D-

)(

1).(Pr )/( 22min

thR

rr

rN

e

LCR

OutageADF

rms

778.277)10*3

6.3/100(*10*3

89

max f

sec10*716.510*771.2/10*84.15

10*771.2

*)10*98.3(*778.277*2)(

9312

3

10*84.156 12

ADF

erN thR

Autocorrelation (* then +)Pr.2

1 1 1 1 Result

1 1 1 1 0

1 1 1 1 1

1 1 1 1 2

1 1 1 1 3

1 1 1 1 4

1 1 1 1 3

1 1 1 1 2

1 1 1 1 1

1 1 1 1 0

0

0.5

1

1.5

2

2.5

3

3.5

4

Peak

AutoCorrelation

Average voltage = 16/4= 4

Cross CorrelationPr.3

1 1 1 1 Result

1 -1 1 -1 0

1 -1 1 -1 -1

1 -1 1 -1 0

1 -1 1 -1 -1

1 -1 1 -1 0

1 -1 1 -1 1

1 -1 1 -1 0

1 -1 1 -1 1

1 -1 1 -1 0

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

CrossCorrelation

Average voltage = 0/4= 0

Rake ReceiverIt’s a well known block for CDMA

receivers to eliminate multipath effect and increase SINR.

Functions: Channel delay estimation or

Impulse Response (IR)Measurement for multipath

componentsProvides a separate correlation

receiver for each of the multipath signals

Mobile Network Generations

1st Generation (1G):Many standardsAnalog System

voice services only No SIM card Limited Roaming

Examples in TableOther Standards:

AMPS (USA) –Bell labs 1970

NTT (Japan)

ARP NMT-900In Use 1971 1986

Frequency Band

150 MHz 900 MHz

Channels 80 400Modulation FM FM

Transmit Power

1 5W 100m, 1 and 6W

Handover in Call

No Yes

Country Finland SwitzerlandPower

Consumption high medium

22ndnd Generation Generation (2G):(2G):Digital Voice

NetworkSlow data rate

(Short Message Service -SMS)

Wider coverage compared to 1G

Roaming supportCircuit Switching

GSM 900 IS-95 PDC

In Use 1991 1993 1993

Frequency Band (Hz)

890960M 824 894M 810 1501M

Channels / carrier

8 64 codes 3

Access TDMA / FDMA

CDMA / FDMA

TDMA / FDMA

Transmit Power

Up to 1W 600 mW

Handover in Call

yes yes yes

Countries Europe 212 countries (70% world)

USA Japan

Channel rate 270.833 kbps 1,228.8 kbps 42 kbps

Voice / data rate

13 / 9.6 kbps 14.4 kbps 6.7 kbps

2.5G:2.5G:GSM GPRS (General packet radio service):

Released in 2001<= 171.2Kbps/carrierVoice Circuit switching, Data Packet switchingMedia Message Service (MMS)

IS-95 IS95BPDC PDC-Data

2.75G2.75G:GPRS EDGE (Enhanced Data GSM Evolution):

Released in 2003<= 473.6 kbps/carrierVoice Circuit switching, Data Packet switchingMMS and Internet access with better quality

3G:3G:WCDMA (Wideband CDMA) = UMTS (Universal Mobile

Telecommunications System):EuropeanCDMA/FDMA1885-2025 MHz (uplink) and 2110-2200 MHZ (downlink)384 kbps Urban outdoor2048 kbps Indoor and low range outdoorSoft Handover (handover with same carrier)accommodate QoS classes for four types of traffic:

Conversational class—Voice, video telephony, video gamingStreaming class— Multimedia, video on demand.Interactive class— Web browsing, network gaming,

database accessBackground class—E-mail, short message service (SMS), file

downloadingLocation Based services.

CDMA2000American

3.5G: UMTS-HSDPA (High Speed Downlink Packet Access) 2005/063.5G: UMTS-HSDPA (High Speed Downlink Packet Access) 2005/06Decreasing delay due to transmission errors Hybrid

Automatic Repeat Request.Decreasing Handover failure Fast cell site selection.Improving resources management Stand alone

downlink shared channelAdaptive Modulation and Coding. Download up to(14.4 Mbps and Upload up to 384

kbps) /sector. 3.75G: UMTS- HSUPA (High Speed Uplink Packet Access) 2007/083.75G: UMTS- HSUPA (High Speed Uplink Packet Access) 2007/08

DL: 14.400Mbps and UL: 5.8Mbps

4G: “in Research”4G: “in Research”Toward 100Mbps with IP core networkToward 100Mbps with IP core network

WiMAXLong Term Evolution (LTE)

ReferencesTommi Heikkilä; S-72.333 Postgraduate

Course in Radio Communications