a location-aided energy-aware routing method for uwb sensor networks xizhi an and kyungsup kwak...

A Location-aided Energy-aware Routing Method for

UWB Sensor Networks

Xizhi An and Kyungsup KwakGraduate School of Information Technology and Telecommunications,

Inha University, Korea

Mykonos, Greece, June 2006

22

1st International Conference on Cognitive Radio Oriented Wireless Networks and Communications

Telecommunication Engineering Telecommunication Engineering LabLab

Outline Introduction

System Model

Routing Scheme Design

Simulation Results

Conclusions

33



Introduction Sensor Network (SN)

Vast usages in people's life; SN consists of, possibly a large number of, tiny devices with

sensing, computing, and communicating capabilities. Design issues

routing scheme, power management, data transfer protocols, etc. Energy awareness is essential.

Ultra-WideBand (UWB) Technique UWB is a promising candidate for sensor network applications.

low complexity and low cost; noise-like signal; robust to multipath fading and jamming; high time-domain resolution; UWB has the lowest consumed energy per bit among different low-

power RF technologies.

44



Introduction In this paper

emphasize the importance of utilizing location information in the route selection;

positioning capability of UWB physical layer try to find the relationship between energy consumption

and route properties; derive a new routing metric concerned with energy.

55



System Model TH-PPM UWB PHY [Win '00]

Max. achievable bit rate = 18 Mbps The relationship between the BER and the SNR can be

obtained through the link-level simulation. Very low transmit power

Max. radio coverage radius of one node ~ 20 meters; Nodes transmit at the max. power if they have data to

send; Positioning capability

Very short pulse wave ~ very high time resolution; The location of node is estimated from the difference of

the arrival time of pulse waves received; Statistical UWB indoor path-loss model [Ghassemzadeh

'03] 0 10 1 10 2 2 3dB( ) 10 log 10 logPL d PL d n d n n n

66



System Model Dynamic Channel Coding MAC [Boudec '04]

rate-compatible punctured convolutional codes: adapt the data rate according to the interference and the channel condition;

private MAC ~ resolve contentions Transport Layer

UDP, packet size = 512 bytes QOS: transfer delay and packet delivery ratio

Energy considerations Satisfy requirements of upper layers and consume as less as

possible energy 4 states of node (for the packet transmitting-receiving

process) Transmit : 60 mW Receive : 30 mW Idle : 0 mW Sleep : 0 mW

77



Routing Scheme Design Impact of Multi-hop Route

Energy consumption and QOS issues Total Energy Consumption per Packet Delivered (Ep). End-to-end Packet Transfer Delay (Td). Packet Delivery Ratio (PDR).

A Simple Line Network Topology

Distance-related Parameters: D : distance between the Sender and the Sink L / Li : length of hop(s) LR : length of the route connecting the Sender and the Sink H : number of hops belonging to the route C : max. radio-coverage radius of node F : optimal forward distance, determined by energy efficiency

88



Routing Scheme Design Empirical Results of the Line Network

20 40 60 80 100 120 1400

1

2

3

4

5

Length of Route (m)

Tot

al E

nerg

y C

onsu

mpt

ion

per

Pac

ket

Del

iver

ed (

mJ)

direct2-hop3-hop4-hop5-hop6-hop7-hop8-hop

(a) Ep curve

0 20 40 60 80 100 120 140

20

40

60

80

100

120

140

Length of Route (m)

End

-to-

end

Pac

ket

Tra

nsfe

r D

elay

(m

s)


(b) Td curve

0 20 40 60 80 100 120 1400

10

20

30

40

50

60

70

80

90

100

Length of Route (m)

Pac

ket

Del

iver

y R

atio

(%

)


(c) PDR curve

99



Routing Scheme Design Some interesting findings

Energy Consumption Processing Loss

• a high-level combination of packet encoding, buffering, processor operating, competing and collision resolving, etc.

Path Loss• PL is proportional to the propagation distance raised to some

exponent.• Larger the distance is, lower the SNR.• low-rate coding or retransmission? Efficiency is reduced.

Compromise – a kind of optimal forward distance (F)?• close nodes: better signal reception, but higher processing los

s and larger number of hops• far nodes: lower processing loss and less number of hops, but

worse signal reception Relationship between Energy and QOS

1010



Energy Metric of Route route length LR :

the lower bound of Ep :

the additional punishment on the hop longer than F :

the energy metric of route:

β accounts for energy loss of relay node.


1, when

( ) ( ) , when

, when

i

i i i

i

L F

C F C L F L C

L C

min RE L

min1

1 ( 1)H

ii

E E H

1

H

R ii

L L

1111



Routing Algorithm -- eLAR Based on the Dijkstra's Algorithm with modification;

The length (or cost) of a hop (or edge) is not directly used, but the overall E metric of the route containing that hop is evaluated.

"Shortest" path problem ~ find the route with min. energy loss; Min. Loss Tree rooted at a Source Node

1. V = {v1, v2, …, vN}; // set of all nodes, N: number of nodes

2. Y = {v1}; // v1 is the source node

3. F = Φ; // min. loss tree (initially empty)

4. while (V ≠ Y) {

5. select a node v from V–Y, that has a min. energy loss

6. from v1, using only nodes in Y as relay nodes;

7. add the new node v to Y;

8. add the hop (on the min-loss route) that touches v to F;

9. }


1212



eLAR Implementation Each node derives its routing table from its min. loss tree;

Complexity ~ O(N2) Some simplification can be made.

Packets can be forwarded sequentially without an extra route header.

Routing Scheme: Step 1. The source node (src) investigates whether the

destination node (dst) is in its near vicinity. If the distance between src and dst, D, is not larger than F, src directly transmits packets to dst; otherwise, src searches its routing table to find the next-hop node (nxt) that is on the minimum loss route to dst and then forwards packets to nxt.

Step 2. The relay node (rly) checks the destination (dst) of each received packet. According to the distance between rly and dst, rly performs the same action as in Step 1.


1313



Simulation Results Network Configuration:

Platform: network simulator ns-2 v2.26;

Routing parameters: F = 10 m, C = 22 m, λ = 1, β = 0.01;

Scenario Area: 50 m × 50 m

Distribution of nodes’ location: random points;

Number of nodes: 48 (1 sink, 47 sensors);

Routing Scheme: LAR vs. AODV.

1414



Simulation Results

0 10 20 30 40 500

10

20

30

40

50

0

1

2

3

4

5

67

89

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

3031

32

3334

35

36

37

38

3940

41

42

43

44

45

4647

Length of Area (m)

Wid

th o

f A

rea

(m)

Static Scenario -- Random network topology

1515



Simulation Results Performance Comparison -- Ep

1 3 8 12 19 29 33 360

1

2

3

4

5

6

7

8

9

10

Sensor ID

Tot

al E

nerg

y C

onsu

mpt

ion

per

Pac

ket

(mJ)

AODVeLAR

1616



Simulation Results Performance Comparison -- Td

1 3 8 12 19 29 33 360

100

200

300

400

500

600

700

Sensor ID

End

-to-

end

Pac

ket

Tra

nsfe

r D

elay

(m

s)

AODVeLAR

1717



Simulation Results Performance Comparison – PDR

1 3 8 12 19 29 33 3630

40

50

60

70

80

90

100

Sensor ID

Pac

ket

Del

iver

y R

atio

(%

)

AODVeLAR

1818



Simulation Results Static

Scenario -- energy loss tree rooted at the sink

0 10 20 30 40 500

10

20

30

40

50

0

1

2

3

4

5

67

89

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

3031

32

3334

35

36

37

38

3940

41

42

43

44

45

4647

Length of Area (m)

Wid

th o

f A

rea

(m)

1919



Conclusions This is a practical work concerned with routing design.

Two main factors of energy consumption are taken into consideration and the relationship between energy and QOS is preliminarily discussed.

A new energy metric is developed based on a priori knowledge.

A corresponding routing scheme “eLAR” is proposed.

Simulation results demonstrate eLAR’s effectiveness and potential.

2020



That’s all. Thanks!

a location-aided energy-aware routing method for uwb sensor networks xizhi an and kyungsup kwak...

Documents

mw1st international

packet size

packet transmitting

energy awareness

radio coverage radius

data rate

uwb sensor networksxizhi

lowest consumed energy