1 performance evaluation of mobile relays in cdma system presented by: md. faisal murad hossain...

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Performance Evaluation of Mobile Relays in CDMA System

Presented By:Md. Faisal Murad [email protected] LaboratoryHelsinki University of Technology

Supervisor:

Prof. Sven Gustav Häggman

Instructor:

Prof. Riku Jäntti

HELSINKI UNIVERSITY OF TECHNOLOGYPerformance Evaluation of Mobile Relays in CDMA SystemMd. Faisal Murad Hossain

2

Outline

• Introduction• Wireless Network Overview

(i) Cellular CDMA Network(ii) Infostation Network(iii) Multihop Cellular Network (MCN)

• Relaying Design Objective in MCN• Mobility Model• Basketball Multihop Scheduling

– Overview– Pseudocode– Relay Selection

• Performance Analysis– Effect of User Density– Effect of Cell Radius

• Conclusion


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Introduction

• The study of this thesis includes proposing a Scheduling Algorithm, for Mobile Relays in Uplink DS-CDMA, which we name as Basketball Multihop Scheduling Algorithm.

• We also compare its performance with other existing technologies e.g; pure CDMA and Infostation Systems.


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Wireless Network Overview(I)

• Cellular CDMA Network– The area that a base station covers around it, in

which communication from and to the base station is achievable, is called its cell, thus the term comes “cellular network”

– It uses the multiplexing scheme CDMA, Code Division Multiple Access.

– Mobile stations communicate only with Base Stations.


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Wireless Network Overview(II)

• Infostation Network– Any mobile node communicates with the base

station only when they are close enough (within the transmit range).


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Wireless Network Overview(III)

• Multihop Cellular Network(MCN)– In MCN the base station and mobile stations

are not always reciprocally accessible in a single hop.

– The key advantage is that the mobile stations can directly communicate with each other provided that they are mutually reachable.

– MCN can perform multihop routing.


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Relaying Design Objective in MCN

• Relaying Design Objective in MCN– Communication range extension.

Transmission through several hops.

– Higher data rates.Short hops-high data rate

– Better Quality.Cooperative Relaying

original signal is received by several relays and forwarded to the destination through different paths so that it does not get stuck with a bad path and can be switched to a good path.

– Improved Capacity Again. simultaneous transmissions by both the BS and the relays.


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Mobility Model

• Mobility Model– We used Directional Random Walk Mobility model.– In the beginning of the simulation, each mobile node picks a random

destination and traverses to that destination in a straight line at a uniform speed.

– When the destination is reached, each mobile node chooses a new destination

– Each mobile node has a higher probability in moving in the same direction as the previous move. And we assigned different probabilities for all other directions as shown in the figure,

so that– The new location of the mobile node depends

on the previous location/direction and speedof the mobile node. When a mobile nodereaches the boundary of the cell, it should flip-over to the reverse direction of the cell.

1*2*2 21 pppi o

05.0,1.0,7.0 210 ppp


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Basketball Multihop Scheduling(I)

• Overview– Basic idea is to deploy Multihop transmission from mobile nodes back

to the base station.– We utilize the similarity between the basketball game and our

Multihop uplink packet scheduling problem. By regarding players, the basket and the ball as mobiles, the base station and data packet, respectively, we can mimic passing (Multihopping) patterns of the basketball players.

– A major difference between the two is that in the Multihopping problem, there are many packets (balls) while in the basket ball game, there is only one ball to shoot into the basket.

– For each CDMA time slot, a number of mobile nodes are selected as relays to let other nodes nearby to send the packets to them.

– A transmitting terminal may select a relaying node that is close to it and meanwhile the relaying node is located closer to the base station than that transmitting one.


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Basketball Multihop Scheduling(II)

• Overview (Contd.) There are two control parameters: Transmission range r, and

relay probability p. Scheduling rule

– A mobile will act as a relay with probability p. If it switch to relay mode, it only receives packet during the

time slot.– A mobile who does not act as relay will try to transmit

If the base station is in its transmission range r, it will transmit to it directly.

If base station is not in its range, the mobile will select the relay node which is closest to the base station and transmit the packet to it.

If there are no relay nodes closer to the base station than the mobile itself, the mobile will remain idle during the slot.


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Basketball Multihop Scheduling(III)


r

Node that triesto transmit

Relay node

Communicationlink

Base station

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Basketball Multihop Scheduling(IV)


Is base stationwithin radio range

Is there any relayswithin radio range

Is any relay closer toThe base station

than the mobile itself

Transmit to the best relaywithin radio range

Stay idleTransmit directly

to the base station

No Yes

YesNo

No Yes

Best relay = relay closest to the base station

• Transmit mode

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Basketball Multihop Scheduling(V)

• PseudocodeAt each slot

– We determined packet arrivals for all users– We Checked which mobiles are relays– We went through transmit mode users and determined

active links– We also determined SINR at the receiver of active links.– Then we determined the packet transmissions in active link

We removed transmitted packets from the transmission buffer of the source nodes and added them to the end of the queue at the destination nodes

If packet were transmitted to the base station, we recorded the packet delay.


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Basketball Multihop Scheduling(VI)

• Relay Selection – Let dij(t) denote the distance between mobile i and mobile j at

time t. Let index 0 denote the base station so that di0(t) is the distance between mobile i and the base station at time instant t. Clearly, d00(t)=0 for all t.

– Let M={1,2,…,N} denote the set of all mobiles and let N={0,1,2,…,N} denote the set of nodes including the base station (i=0).

– Let R(t)µN denote the set of relay nodes at time slot, t. We assumed that a node i becomes a relay at time t with probability pi(t)¸ 0, p0(t)=1. That is the base station is always willing to act as a relay for all the nodes. All other nodes are wireless relays except the base station which relays the packet to the core network (e.g. internet).

– Let A(t)µM denote the set of active nodes. I.e. the nodes that are not acting as relays


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Basketball Multihop

Scheduling (VII)

• Relay Selection (Contd.)– A node i2A(t) selects relay ki using the following rule

where 0··1 is a weighting parameter and Fi(t) denotes the set of feasible relays from mobile i.

– The feasible set includes all the nodes that are within the radio range r from the mobile i and are closer to the base station than the node i. The parameter 0<·1 denotes a margin. A relay node is only accepted if its distance to the base station is less than that for node i.

( ) 0arg max 1 , ( )ii j t ij jk d d i t F A


0 0( ) | ( ), ,i ij j it j j t d r d d F R

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Basketball Multihop Scheduling (VIII)


i

jdi0

dij

di0

dj0

r

Feasible relaysMust lie in the intersection of the two circles

Feasible (candidate) relay

Unfeasible relay

Node transmitting a packet

( ) { }i

i

t j

k j

F

• Relay Selection (Contd.)

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Performance Analysis(I)

• Performance Analysis– Simulation results are analyzed for the

comparison of Basketball Multihop system with CDMA and Infostation systems with the help of CDF plots.

– Analysis based on Packet Delays and Throughputs for different systems.


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Performance Analysis(II)

Table 1: Simulation Parameters

Parameter Value

No. of Nodes 100

Relay Probability 0.2

Simulation Time 120 sec

Radius of Cell 5 Km

Attenuation Factor 4

MS Transmit power 0.1 W

Noise Power 1 pW

Slot Length 10 mS

Mean Inter-Arrival Time (80e-3)/3 sec

Std. of Inter-Arrival Time 5e-3

Transmission Range 250 m

Min. Mobile Speed 70*1000/3600 m/s

Max. Mobile Speed 100*1000/3600 m/s

Packet Size 10 bytes

Bandwidth 1.25e6 Hz


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Performance Analysis(III)

• Effect of User Density


Packet Delay NormalizedThroughput

Cases Mean(sec.)

Variance(sec.)

Mean Variance SystemPacket

Delay (sec.)

SystemThroughpu

t(pkts/sec)

BasketballMultihop

0.6e+3CI:0.96

7.8e+5 1.1CI: 0.92

9.0 1.0 111.5

Pure CDMA 1.3e+3CI:0.96

3.6e+6 6.9CI: 1.0

119.6 6.1 697.8

One hopInfostation

2.2e+3CI: 1.0

8.0e+6 1.0CI: 1.0

18.8 0.9 103.6

Table 2: Mean and Variance of data (N=100)

• From Table 2, it can be said that with 100 users in the cell, the Basketball Multihop system incurs less mean packet delay than CDMA and Infostation systems. System Packet Delay for Basketball Multihop system is almost similar as Infostation system but significantly less than CDMA system.

• Again from Table 2, Throughput for Basketball Multihop is almost similar as Infostation system but worse than CDMA system.

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Performance Analysis(IV) HELSINKI UNIVERSITY OF TECHNOLOGYPerformance Evaluation of Mobile Relays in CDMA SystemMd. Faisal Murad Hossain

0 2000 4000 6000 8000 10000 120000

0.2

0.4

0.6

0.8

1

Time Slots

Pac

ket

Del

ay (

Pro

babi

lity)

Comparison of Packet Delay (CDF)

Basketball

CDMAInfostation

Figure 1: Comparison of Packet Delays for different systems, N=100

• It can be seen from Figure 1 that for Basketball Multihop case, 80% of the time the packets will be delivered within 2000 time-slots whereas for CDMA case, 80% of the time the packets will be delivered within around 3000 time-slots and for Infostation case, 80% of the time the packets will be delivered within 4400 time-slots.

• Hence Basketball Multihop system is clearly better than the other two systems as the Service probability is better in this system with less delay maintaining good Quality of

Service (QoS).

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Performance Analysis(V)

• Our results indicate that for Basketball Multihop case 100 users can be supported with 90% probability whereas for CDMA case 92 users can be supported with 90% probability and for Infostation case 98 users can be supported with 90% probability.

• Hence Basketball Multihop system is better than the other two systems with respect to

Throughput.


0 0.2 0.4 0.6 0.8 165

70

75

80

85

90

95

100Comaprison of Throughput (CDF)

User Throughput (Probability)

No.

of U

sers

Basketball

CDMAInfostation

Figure 2: Comparison of Throughputs for different systems, N=100

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Performance Analysis(VI) HELSINKI UNIVERSITY OF TECHNOLOGYPerformance Evaluation of Mobile Relays in CDMA SystemMd. Faisal Murad Hossain

Packet Delay Normalized Throughput

Cases Mean(sec.)

Variance(sec.)

Mean Variance System PacketDelay (sec.)

SystemThroughput

(pkts/sec)

BasketballMultihop

2.5e+3CI: 1.0

6.8e+6 11.1CI: 1.0

81.3 29.0 8.3e+3

Pure CDMA 2.1e+3CI: 1.0

5.3e+6 2.0CI: 1.0

39.8 2.8 1.5e+3

One hopInfostation

1.8e+3CI: 1.0

6.3e+6 0.8CI: 1.0

12.9 0.7 654.2

Table 3: Mean and Variance of data (N=750)• Effect of User Density (Contd.)

• From Table 3, it can be seen that with 750 users in the cell, the Basketball Multihop system incurs more packet delay than CDMA and Infostation systems.

• Again from Table 3, Throughput for Basketball Multihop is greatly increased

than the other two systems.

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Performance Analysis(VII) HELSINKI UNIVERSITY OF TECHNOLOGYPerformance Evaluation of Mobile Relays in CDMA SystemMd. Faisal Murad Hossain

0 2000 4000 6000 8000 10000 120000

0.2

0.4

0.6

0.8

1

Comparison of Packet Delay

Time Slots

Pac

ket

Del

ay (

Pro

babi

lity)

Basketball

InfostationCDMA

Figure 3: Comparison of Packet Delays for different systems, N=750

• The results indicate that for Basketball Multihop case, 80% of the time the packets will be delivered within 6400 time-slots with 0.8 service probability and 0.2 outage probability, whereas for CDMA case, 80% of the time the packets will be delivered within around 4400 time-slots and for Infostation case, 80% of the time the packets will be delivered within 3800 time-slots.

• Hence Basketball Multihop system is worse than other two systems with respect to packet delays.

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Performance Analysis(VIII)

• The results suggest that for basketball Multihop case 750 users can be supported with 95% probability whereas for CDMA case 750 users can be supported with 95% probability and for Infostation case 750 users can be supported with 85% probability.

• Thus, it can be said that if the number of user is increased, the Throughput for Basketball Multihop system is increased significantly, becomes stable with good service probability but incurs much packet delay.


0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1200

250

300

350

400

450

500

550

600

650

700

750Comparison of Throughput (CDF)

User Throughput

No.

of

Use

rs

Basketball

InfostationCDMA

Figure 4: Comparison of Throughputs for different systems, N=750

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Performance Analysis(IX)

• Effect of Cell Radius


Table 4: Mean and Variance of data (R=1 Km)Packet Delay Normalized Throughput

Cases Mean (sec.) Variance (sec.)

Mean Variance System Packet Delay

(sec.)

System throughput (pkts/sec)

Basketball Multihop

211.5CI: 0.96

1.0e+5 31.5CI: 0.96

0.07 2.1 3.1e+3

Pure CDMA 2.4 e+3CI: 0.96

7.3e+6 23.0CI: 1.0

119.2 33.9 2.3e+3

One hop Infostation

2.6e+3CI: 0.96

6.3e+6 12.5CI: 0.96

167.8 14.9 1.2e+3

• It can be seen from Table 4, that Basketball Multihop system can provide less packet delay and more throughput than CDMA and Infostation systems in a small cell with 1 km radius.

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Performance Analysis(X) HELSINKI UNIVERSITY OF TECHNOLOGYPerformance Evaluation of Mobile Relays in CDMA SystemMd. Faisal Murad Hossain

0 2000 4000 6000 8000 10000 120000

0.2

0.4

0.6

0.8

1

Comparison of Packet Delay (CDF)

Time Slots

Pac

ket D

elay

(Pro

babi

lity)

Basketball

CDMAInfostation

Figure 5: Comparison of Packet Delays for different systems, R= 1Km

• From the Figure 5, it can be seen that for Basketball Multihop case, 80% of the time the packets will be delivered within 4000 time-slots with 0.8 service probability and 0.2 outage probability, whereas for CDMA case, 80% of the time the packets will be delivered within around 4200 time-slots and for Infostation case, 80% of the time the packets will be delivered within 5100 time-slots.

• Basketball Multihop system is better than the other two systems with respect to packet

delays.

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Performance Analysis(XI)

• The results indicate that for basketball Multihop case 100 users can be supported with 100% probability whereas for CDMA case 100 users can be supported with 96% probability and for Infostation case 100 users can be supported with 96% probability.

• Basketball Multihop system is again better than other two systems with respect to Throughput.


0 0.2 0.4 0.6 0.8 10

10

20

30

40

50

60

70

80

90

100Comparison of Throughput (CDF)

User Throughput (Probability)

No.

of U

ser

Bassketball

CDMA

Infostation

Figure 6: Comparison of Throughputs for different systems, R= 1Km

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Performance Analysis(XII)

• Effect of Cell Radius (Contd.)


Table 5: Mean and Variance of data (R=5 Km)

Packet Delay Normalized Throughput

Cases Mean (sec.) Variance (sec.)

Mean Variance System Packet Delay

(sec.)

System throughput (pkts/sec)

Basketball Multihop

0.7e+3CI: 0.96

6.9e+5 7.1CI: 0.92

11.0 0.8 711.5

Pure CDMA 1.1e+3CI: 0.96

3.3e+6 4.9CI: 1.0

117.6 4.1 497.8

One hop Infostation 2.2e+3CI: 1.0

8.0e+6 1.0CI: 1.0

18.8 0.9 103.6

• From Table 5, it can be said that with large cell radius (5 Km) Basketball Multihop system provides less delay than the other two systems CDMA and Infostation systems.

• Again from Table 5, Throughput for Basketball Multihop is better than Infostation and CDMA systems when the cell radius is increased to 5Km.

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Performance Analysis(XIII) HELSINKI UNIVERSITY OF TECHNOLOGYPerformance Evaluation of Mobile Relays in CDMA SystemMd. Faisal Murad Hossain

0 2000 4000 6000 8000 10000 120000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Time-slots

Pac

ket D

elay

(pro

babi

lity)

Comparison of cdf-packetdelay

Basketball

CDMA

Infostation

Figure 7: Comparison of Packet Delays for different systems, R= 5Km

• The results suggest that for Basketball Multihop case, 80% of the time the packets will be delivered within 800 time-slots, whereas for CDMA case, 80% of the time the packets will be delivered within around 3000 time-slots and for Infostation case, 80% of the time the packets will be delivered within 3500 time-slots.

• Hence Basketball Multihop system is clearly better than the other two systems with respect to packet delays.

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Performance Analysis(XIV)

• From the Figure 8, it can be seen that for Basketball Multihop case, from 28 to 100 users can be supported with 100% probability whereas for CDMA case from 32 to 100 users can be supported with 100% probability and for Infostation case from 28 to 100 users can be supported with 100% probability. Yet Basketball Multihop system is more stable than CDMA because it can provide any user with more than 80% probability which CDMA cannot provide.

• Thus we can see that the Basketball Multihop system works better in a larger cell with respect to both Packet Delay and Throughput.


0 10 20 30 40 50 60 70 80 90 100

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

No. of Users

Use

r thr

ough

put (

prob

abili

ty)

Comparison of cdf-throughput

Basketball

Infostation

CDMA

Figure 8: Comparison of Throughputs for different systems, R= 5Km

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Conclusion

• Conclusion The simulations have shown that there certainly is a need for relaying

in cellular networks due to improved capacity and shorter delays. However the Basketball Multihop system works better for the

following conditions:

– More users for increased throughput and stability

– Larger cell for both shorter delay and improved throughput

– Highway-vehicle users for both increased throughput and improved delay

– High traffic volume for both shorter delays and higher throughput

– Short Transmission range for both improved delays and increased throughput.


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1 performance evaluation of mobile relays in cdma system presented by: md. faisal murad hossain...

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