a cooperative diversity- based robust mac protocol in wireless ad hoc networks sangman moh, chansu...

23
A Cooperative Diversity-Based Robust MAC Protocol in wireless Ad Hoc Networks Sangman Moh, Chansu Yu Chosun University, Cleveland State University Korea, Cleveland IEEE TPDS, March 2011 1

Upload: ami-chase

Post on 28-Dec-2015

215 views

Category:

Documents


0 download

TRANSCRIPT

Page 1: A Cooperative Diversity- Based Robust MAC Protocol in wireless Ad Hoc Networks Sangman Moh, Chansu Yu Chosun University, Cleveland State University Korea,

1

A Cooperative Diversity-Based Robust

MAC Protocol in wireless Ad Hoc

NetworksSangman Moh, Chansu Yu

Chosun University, Cleveland State UniversityKorea, Cleveland

IEEE TPDS, March 2011

Page 2: A Cooperative Diversity- Based Robust MAC Protocol in wireless Ad Hoc Networks Sangman Moh, Chansu Yu Chosun University, Cleveland State University Korea,

2

OutlineO IntroductionO Background O Cooperative Diversity MACO Performance EvaluationO Conclusion and Future Work

Page 3: A Cooperative Diversity- Based Robust MAC Protocol in wireless Ad Hoc Networks Sangman Moh, Chansu Yu Chosun University, Cleveland State University Korea,

3

IntroductionO In wireless ad hoc networks, signal fading

and interference are two major obstacles in realizing their full potential in delivering signals.

O Cooperation among the nodes is considered critically important in addressing these problems.

O It may be difficult to maximize the performance unless nodes are coordinated to cooperate at lower levels.O MAC- and PHY- layer

Page 4: A Cooperative Diversity- Based Robust MAC Protocol in wireless Ad Hoc Networks Sangman Moh, Chansu Yu Chosun University, Cleveland State University Korea,

4

Introduction O Recently, some researches in developing

cooperative MAC algorithms O Path-centric medium access O MAC-layer packet relaying

O is determined in a proactive mannerO is used to forward frames at higher bit ratesO but not enhance the communication

reliability, especially in interference-rich environment

O Cooperative communicationO enhance the link reliability

Page 5: A Cooperative Diversity- Based Robust MAC Protocol in wireless Ad Hoc Networks Sangman Moh, Chansu Yu Chosun University, Cleveland State University Korea,

5

IntroductionO Cooperative communication exploits

diversity offered by multiple users, known as multiuser or cooperative diversity.

O It dramatically improves bit error rate (BER).O More reliable transmissionO Higher throughput

Page 6: A Cooperative Diversity- Based Robust MAC Protocol in wireless Ad Hoc Networks Sangman Moh, Chansu Yu Chosun University, Cleveland State University Korea,

6

Background

OCooperative DiversityOCooperative Diversity in

Wireless Ad Hoc Networks

Page 7: A Cooperative Diversity- Based Robust MAC Protocol in wireless Ad Hoc Networks Sangman Moh, Chansu Yu Chosun University, Cleveland State University Korea,

7

Cooperative DiversityO Two types of cooperative diversity

algorithmsO Repetition-based

O Amplify-and-forwardO Decode-and-forward

O Space-time-codedO Distributed space-time coding (DSTC)O Space-time coding (STC) (multiantenna

system)O Space-time block coding (STBC)

(multiantenna system)

Page 8: A Cooperative Diversity- Based Robust MAC Protocol in wireless Ad Hoc Networks Sangman Moh, Chansu Yu Chosun University, Cleveland State University Korea,

8

DSTC

Page 9: A Cooperative Diversity- Based Robust MAC Protocol in wireless Ad Hoc Networks Sangman Moh, Chansu Yu Chosun University, Cleveland State University Korea,

9

Cooperative Diversity in Wireless Ad Hoc NetworksO Azgin et al. proposed Cooperative

MAC (C-MAC) and the corresponding routing protocols for wireless ad hoc network. (GlobeCom 2005) O Relaying start (RS)O Relay acknowledgement (RA)O Relay broadcasting (RB)O Transmission start (TS)O RTS-CTS-RS-RA-RB-TS-ACK

Page 10: A Cooperative Diversity- Based Robust MAC Protocol in wireless Ad Hoc Networks Sangman Moh, Chansu Yu Chosun University, Cleveland State University Korea,

10

Cooperative Diversity MAC

O Overview

Page 11: A Cooperative Diversity- Based Robust MAC Protocol in wireless Ad Hoc Networks Sangman Moh, Chansu Yu Chosun University, Cleveland State University Korea,

11

A Simple Cooperative scheme

O The authors proposed in ICC 2007.O Based on DCF of the IEEE 802.11

standardO If a primary link is reliable enough to

successfully transmit frames, no cooperative transmission is enabled.

O If it fails, the sender retransmits the frame but cooperatively with its partnerO When to cooperate

Page 12: A Cooperative Diversity- Based Robust MAC Protocol in wireless Ad Hoc Networks Sangman Moh, Chansu Yu Chosun University, Cleveland State University Korea,

12

A case for simple scheme

Page 13: A Cooperative Diversity- Based Robust MAC Protocol in wireless Ad Hoc Networks Sangman Moh, Chansu Yu Chosun University, Cleveland State University Korea,

13

Problems of simple scheme

O Twice longer than that without cooperation

O An RTS failure can be due to collisions/interference from other nodes’ communication

O The RTS/CTS exchange effectively eliminates the problem associated with “the hidden terminals”.

Page 14: A Cooperative Diversity- Based Robust MAC Protocol in wireless Ad Hoc Networks Sangman Moh, Chansu Yu Chosun University, Cleveland State University Korea,

14

Cooperative Diversity MAC

Page 15: A Cooperative Diversity- Based Robust MAC Protocol in wireless Ad Hoc Networks Sangman Moh, Chansu Yu Chosun University, Cleveland State University Korea,

15

State transition diagrams

Sender

Receiver

Partner

Page 16: A Cooperative Diversity- Based Robust MAC Protocol in wireless Ad Hoc Networks Sangman Moh, Chansu Yu Chosun University, Cleveland State University Korea,

16

Partner Selection and Its Propagation

O Every node proactively selects its partner by monitoring or overhearing its neighbors with respect to link quality.

O Measure and record the link quality while receiving a frame

O The neighbor with the best link quality among all neighbors is chosen as its partner.

Page 17: A Cooperative Diversity- Based Robust MAC Protocol in wireless Ad Hoc Networks Sangman Moh, Chansu Yu Chosun University, Cleveland State University Korea,

17

Why choose the neighbor with the best link quality?O Three reasons behind this choice

O Communication between a node and its partner must be highly reliable.

O A partner with the best link quality is most probably the closest node.

O It ensures that the sender and the partner share the same communication environment so that they can make a consistent decision on cooperation.

Page 18: A Cooperative Diversity- Based Robust MAC Protocol in wireless Ad Hoc Networks Sangman Moh, Chansu Yu Chosun University, Cleveland State University Korea,

18

Performance Evaluation

O Using ns-2 simulatorO 50 mobile nodes move over a square area

of 300X1500 m2

O Each simulation runs for 900 seconds. O Source-destination pairs are randomly

selected.O Mobile nodes are assumed to move

randomly with the node speed of 0-5 m/secO Pause time between moves varies from 0

to 900 seconds.

Page 19: A Cooperative Diversity- Based Robust MAC Protocol in wireless Ad Hoc Networks Sangman Moh, Chansu Yu Chosun University, Cleveland State University Korea,

19

Performance Comparison

This is due to the complex interplay among MAC- and routing-layer protocols in MANET environment

Page 20: A Cooperative Diversity- Based Robust MAC Protocol in wireless Ad Hoc Networks Sangman Moh, Chansu Yu Chosun University, Cleveland State University Korea,

20

Overhead and cooperation efficiency

Page 21: A Cooperative Diversity- Based Robust MAC Protocol in wireless Ad Hoc Networks Sangman Moh, Chansu Yu Chosun University, Cleveland State University Korea,

21

Impact of environment noise

Page 22: A Cooperative Diversity- Based Robust MAC Protocol in wireless Ad Hoc Networks Sangman Moh, Chansu Yu Chosun University, Cleveland State University Korea,

22

Effect of network traffic on packet delivery ratio

Page 23: A Cooperative Diversity- Based Robust MAC Protocol in wireless Ad Hoc Networks Sangman Moh, Chansu Yu Chosun University, Cleveland State University Korea,

23

Conclusions and Future Work

O This paper proposed CD-MAC and discusses design issues and performance benefits in wireless ad hoc network.

O When a communication link is unreliable, a sender transmits its signal together with its partner delivering the signal more reliably.

O As a future work, exploiting cooperative diversity based on multichannel interfaces will be investigated.