Link-Utility-Based Cooperative MAC Link-Utility-Based Cooperative MAC Protocol for Wireless Multi-Hop NetworksProtocol for Wireless Multi-Hop Networks

Yong Zhou, Ju Liu, Lina Zheng, Chao Zhai, He Chen

National Mobile Communications Research Laboratory

School of Information Science and Engineering,

Shandong University, Jinan, China

IEEE Transactions on Wireless Communications, vol. 10, no. 3, March 2011, pp. 995–1005

Outline

• Introduction

• Related Word

• Goals

• System Model

• Link-utility-based cooperative MAC (LC-MAC)

• Simulation

• Conclusion

Introduction

• Obstacles of realizing the full potential of delivering packets– Channel fading

– Signal interference

Introduction

• Multiple-input multiple-output (MIMO) systems on a single node can improve signal quality– Limited physical size

– Cost constraints

Introduction

• Cooperative Transmissions– Virtual antenna array

• Improve signal quality

• Enhance the performance of both throughput and energy-efficiency

Introduction

• Cooperative Coding: Alamouti code (21) – Two-node cooperation: 2 transmit antennas, 1 receive antenna

• Two-node cooperation is better than multi-node cooperation

• Orthogonal code design is not available for more than two cooperation nodes without decreasing data rate [23]

[23] Y. Fan and J. Thompson, “MIMO configurations for relay channels: theory and practice,” IEEE Trans. Wireless Commun., vol. 6, pp. 1774-1786, May 2007.

Introduction

• Compared to the single-input single-output (SISO) link– Virtual MISO link can achieve diversity gain

– Reflect into a decrease in the reception threshold at the receiver

[19] S. M. Alamouti, “A simple transmit diversity technique for wireless communications,” IEEE JSAC, vol. 16, pp. 1451-1458, Oct. 1998.

[20] Y. Zhou, J. Liu, C. Zhai, and L. Zheng, “Two-transmitter two-receiver cooperative MAC protocol: cross-layer design and performance analysis,” IEEE TVT, vol. 59, no. 8, pp. 4116-4127, Oct. 2010.

Related Work

• All existing cooperative MAC protocols are mostly– designed for wireless single-hop networks

– two-phase cooperative transmission

N

A B1. Direct Transmission

[12] T. Guo and R. Carrasco, “CRBAR: Cooperative relay-based auto rate MAC for multirate wireless networks,” IEEE Transactions on Wireless Communications, vol. 8, no. 12, pp. 5938–5947, Dec. 2009.

O 2. Relay-based transmission

Related Work

• CRBAR [12] does not fully exploit– the broadcast nature of wireless multi-hop networks

[12] T. Guo and R. Carrasco, “CRBAR: Cooperative relay-based auto rate MAC for multirate wireless networks,” IEEE Transactions on Wireless Communications, vol. 8, no. 12, pp. 5938–5947, Dec. 2009.

F

NL

S A B D

F

NL

S A B D

S → A → N → B → L → DS → {A, F} → B → L → D

CRBAR [12]This paper

partner

relay

Goal

• Design a novel link-utility-based cooperative MAC protocol (LC-MAC) with distributed helper selection in wireless multi-hop networks– link throughput

– energy consumption

P

O

N

C

M

R

Q

T

KI

G

F H

E N

J

L

S A B D

System model

• Channel state information (CSI) can be estimated by receivers

• Each node – is equipped with one Omni-directional antenna

– has a maximum transmission power (PX) constraint

System model

• maximum transmission power (PX) constraint

– Pt: Transmission Power

– H: channel gain between the transmitter and receiver

– N0: noise variance

– PI: total interference power at receiver

– 𝜃𝑐𝑜𝑛: reception threshold

𝑃𝑋 ≥ 10𝜃𝑐𝑜𝑛/10(𝑁0 + 𝑃𝐼 ) / |𝐻|2

2

t/10

0

10 SNR

I

P H

N P

/100

t 2

10 ( )SNRIN P

PH

2

tsignal

noise 0

10log 10logI

P HPSNR

P N P

System model

• Channel state information (CSI) can be estimated by receivers

• Each node – is equipped with one Omni-directional antenna

– has a maximum transmission power (PX) constraint

LC-MAC: transmission types

• Transmission Type, which is determined by the best helper– CT1: one-phase cooperative transmission (partner)

– CT2: two-phase cooperative transmission (relay)

– DT: direct transmission (transmitter)

P

O

N

C

M

R

Q

T

KI

G

F H

E N

J

L

S A B D

LC-MAC: transmission types

• Partners of A: E, F– Partners have currently received data packets from S

– CT1: one-phase cooperative transmission

P

O

NR

Q

T

KI

G

H

N

J

L

S A B D

C

M

LC-MAC: transmission types

• Relays of A: G, H, I, N– Relays have not currently received data packets from S

– CT2: two-phase cooperative transmission

P

O

N

C

M

R

Q

T

KF

E

J

L

S A B D

LC-MAC: transmission types

• A: no suitable helper– DT: direct transmission

P

O

N

C

M

R

Q

T

KI

G

F H

E N

J

L

S A B D

LC-MAC: CT1

• LC-MAC: distributed three-stage backoff scheme– One-phase cooperative transmission

LC-MAC: CT1

• LC-MAC: distributed three-stage backoff scheme– One-phase cooperative transmission

P

O

NR

Q

T

KI

G

H

N

J

L

S A B D

A

B

C

M

LC-MAC: CT1

• RTS: Extension of the 802.11 RTS frame– Carry the length of data packets (L) in bits

– A waits for CTS frame: TRTS + TSIFS + TCTS

P

O

NR

Q

T

KI

G

H

N

J

L

S A B D

A

B

RTS

SNR(A→F)

C

M

LC-MAC: CT1

• CTS: Extension of the 802.11 CTS frame– Carry the instantaneous SNR of direct link

– B sets data packets timeout: TCTS + Tinter + Tintra + Tre + TRTH + 3TSIFS

P

O

NR

Q

T

KI

G

H

N

J

L

S A B D

A

B

CTS

SNR(B→F), SNR(B→A)

C

M

LC-MAC: CT1

• Power and rate of A and F should be set the same– F:

P

O

NR

Q

T

KI

G

H

N

J

L

S A B DCTS

RTS

C

M

SNR1(B→A)SNR2(B→F)

LC-MAC: CT1

• Link utility (LU) = U – cE– U: link throughput

– E: energy consumption

A

B

LC-MAC: CT2

• LC-MAC: distributed three-stage backoff scheme– Two-phase cooperative transmission

A

B

LC-MAC: CT2

• LC-MAC: distributed three-stage backoff scheme– Two-phase cooperative transmission

P

O

NR

Q

T

K

J

L

S A B DCTS

RTS

C

M F

E

A

B

SNR1(A→N)SNR2(N→B)

LC-MAC: CT2

• The appropriate power of N

– N:

P

O

NR

Q

T

K

J

L

S A B DCTS

RTS

C

M F

E

SNR1(A→N)SNR2(N→B)

LC-MAC: CT2

• Link utility (LU) = U – cE– U: link throughput

– E: energy consumption

A

B

LC-MAC: helper selection

• LC-MAC: distributed three-stage backoff scheme– Inter-group contention (G)

– Intra-group contention (M)

– Re-contention (K)

LC-MAC: helper selection

P

O

NR

Q

T

K

J

L

S A B D

C

M

– Re-contention (K)– Inter-group

contention (G)– Intra-group

contention (M)

LC-MAC: DT

• LC-MAC: distributed three-stage backoff scheme– Direct transmission

Simulation Setup

• Four-hop chain topology network

• Nodes are uniformly distributed in 400x200 m2 area

Simulation Results

Simulation Results

Simulation Results

Simulation Results

Conclusion

• A link-utility-based cooperative MAC (LC-MAC) protocol with distributed helper selection for wireless multi-hop networks is proposed. – Jointly adjust

• Transmission type

• Power

• Rate

TheEND