EM-MAC: A Dynamic Multichannel Energy-Efficient MACProtocol for Wireless Sensor Networks

2014. 11. 11

Bonhyun Koo

Lei Tang*, Yanjun Sun†, Omer Gurewitz‡, and David B. Johnson*

*Department of Computer Science, Rice University, Houston, TX, USA†Systems and Applications R&D Center, Texas Instruments, Dallas, TX, USA

‡Department of Communication Systems Engineering, Ben Gurion University, Israel

MobiHoc’11

Contents

1. Introduction (Goal and Contributions)

2. Related Works

3. EM-MAC Protocol Design

- Design Overview

- Dynamic Channel Selection

- Precise and Quick Multichannel Ren-

dezvous

4. Performance Evaluation

- Multichannel Rendezvous

- Multihop Networks

- Wireless Interference

5. Conclusion

1. Goal and Contributions

Problem1) Traffic Loads (Energy Efficient Operation and Robust Support for varying)2) Wireless Interference (Example. Jamming Attacks)

Purpose

- Introduction of novel mechanism (EM-MAC) for adaptive receiver-initiated multichannel rendezvous and predictive wake-up scheduling

- A predictive and asynchronous duty-cycling MAC protocol (no control channel, dynamic channel selection)

Validation The lowest Sender and Receiver duty cycles and packet delivery latency 100% packet delivery ratio (PDR)

2. Related Works

- Comparison with previous MAC Protocols

Channel Type Protocols Problems

Single Radio Channel S-MAC, B-MAC, RI-MAC,PW-MAC, DW-MAC

Limitation of Network Throughput

Multiple Orthogonal Radio Channel

Y-MAC, A-MAC, MMAC, CAM-MAC

(Dedicated) Control Channel(interference, jamming attack)

Multiple Channel

MMSN, TMMAC (Assuming) Precise Time Synchronization

MuChMACFixed Channel Set

(without adapting to Channel Conditions)

3. EM-MAC (Design Overview)

Sender S, Receiver R Only three of the channels (i, j, and k) At the time of R’s second beacon, no node has a packet waiting to send to R.

Protocol Example

MICAz motesNch = 16, TmaxInterval =1500ms (500~1500ms)

• EM-MAC is a receiver-initiated MAC protocol • A node sends a wake-up beacon to notify potential senders (awake and ready to receive data packets)

3.1 EM-MAC Protocol Design• EM-MAC uses a pseudorandom function (LCG : Linear Congruential Generator) • Applied to (1) Channel and (2) Wake-up Time

Xn+1 = (aXn + c) mod m

m > 0 is the modulus,

a : multiplierc : incrementXn : current seed

Xn+1 becomes the next seed

m =7, a=3, c=0, X0=6

Example)

X1 = (3x6 + 0) mod 7 = 4

X2 = (3x4 + 0) mod 7 = 5

X7 = (3x2 + 0) mod 7 = 6

:

6,4,5,1,3,2, 6,4,5…

period : m-1(6)

Xn+1 = (aXn + c) mod m

Xn

Xn+2 = (aXn+1 + c) mod m

Xk = (aXk-1 + c) mod m

:

Node’s MAC address

3.1 EM-MAC Protocol Design• (Sender) Prediction Mechanism - Predicts the wake-up times and channels of a receiver based on ‘prediction state’

: Sender

(S)

Receiver(R) :

• Nch = 16• TmaxInterval =1500 ms• Tblack = 100 s

1

2

3

4

16

1

2

3

4

16

Ch.

Ch.

Waiting Tblack + 2 x Nch x TmaxInterval

DATA

I want to

send m

y DATA!

B

B

DATA B

DATA B

set a flag (in Header)

prediction state information(a, c, Xn, timestamp)

Channelnext : (300x10+300) mod16 = 4

Intervalnext : (300x60+300) mod500= 100 (ms)

Example: (300, 300, {10,60} , timestamp)

B DATA B

B DATA B

3.2 Dynamic Channel Selection

1) Detecting Channel Conditions

2) Multichannel Rendezvous with Blacklisted Channels

- Nodes maintains for each channel “badness” metric.

Ch. badness

1 5

2 1

: :

16 2

- Every Nodes maintains its own channel blacklist

Reset after Tblack Time (1000 ms)(badness = 0)

Assignment 2 bytes to Header

3.3 Precise and Quick Multichannel Rendezvous1) Adaptive Time Modeling

2) Sender Wake-up Time & Exponential Chase Algorithm

y = kx + b k=1 case, it doesn’t need additional clock sync. y1 = kx1+b

y2 = kx2+b

DATA B

DATA B

set a flag (in Header)

timestamp

y : the current time of Rx : the current time of Sk : clock rate differenceb : initial clock difference

Sender(S)

Receiver(R) B B

#1 #2

wake-upadvance time Fail

reset wake-up advance time

>Tgiveup

Decisionpowered offorout of range

4. Evaluation on MICAz MOTES

1) Performance on Multichannel Rendezvous

Experimental Environments

(S) (R)

R’s clock rate was Increased(until the sender failed)

Node wake-up interval : 1 sWake-up adv. Time : 20 ms30 times (repeat)

R’s clock rate was accelerated by 3000ppm

4. Evaluation on MICAz MOTES

3) Performance with Wireless Interference

Performance With Wireless Interference and Jamming

2) Performance on Multihop Networks

#flow1

#flow2

#flow328-byte data packet(every second)