TDMA based MAC protocol to assist in Wide area Sensor Network Deployment  
 
 
 
This thesis was submitted to the Department of Electronic & Telecommunication of 
the University of Moratuwa in partial fulfillment for the degree of Master of 
Science 
 
By 
N. S. Gajaweera 
 
 
Supervised by 
Prof. Dileeka Dias 
 
 
 
 
 
Department of Electronic and Telecommunication 
University of Moratuwa 
Sri Lanka 
 
May 2009 
 ii 
 
 
DECLARATION 
 
The work included in this thesis, in part or whole has not been 
submitted for any other academic qualification at any 
institution. 
 
 
................................ 
Nuwan Gajaweera 
M.Sc. research (full time) 
Dept. of Electronic & Telecom 
University Moratuwa 
(Candidate) 
 
 
I endorse the declaration by the candidate. 
 
 
 
................................ 
Prof. Dileeka Dias 
Professor 
Dept. of Electronic & Telecom 
University of Moratuwa 
(Supervisor) 
 iii 
 
ACKNOWLEDGMENT 
 
I would like to thank my supervisor Prof. Dileeka Dias for her 
valuable advice, support and encouragement throughout my 
period of study. I would also like to thank the Dialog UoM 
Mobile Communication Lab for funding my work.  
 
Special thanks go out to the staff of the Dialog-UoM Mobile 
Communication lab for their constant support and friendship 
right throughout my period of study. I would like to thank 
head of the Electronics & Telecommunication Mr. Kithsiri 
Samarasingha as well as the members of the academic staff 
for their support and on constructive criticism that kept me on 
the right track. I would like to thank my parents for their 
enthusiasm in all my achievements and for pointing my head 
in the right direction from day one.  
 
And last but not least I would like to thank my wife for her 
patience during difficult times and for the love and support 
she gives me in all my endeavours. 
 
Nuwan Gajaweera 
February 2009 
 
 iv 
ABSTRACT 
Wireless sensor networks are an emerging area of interest among research groups 
around the globe. It is envisioned that these low power computers will become the 
enabling technology in pervasive computing and bring about the next paradigm shift 
in computing.  
The purpose of this work has been the development of enabling technologies for a 
sensor network deployment over a wide geographical area. Chief among these is the 
development of a time division multiple access (TDMA) based MAC protocol for a 
special type of mobile wireless sensor network. In this network, mobile sensor nodes 
will sense the environment, and buffer the measured data for later retrieval. Once 
within range of the base station, the mobile mote will upload the buffered data to 
the base station. Such a system could be used in applications such as analyzing 
migration patterns of animals (ex. Elephants) or offline monitoring of vehicle fleets. 
We present a MAC protocol developed by combining floor acquisition multiple 
access (FAMA) and TDMA that will maximize the throughput of the said network, 
and thereby ensure that the maximum amount of data can be uploaded by the 
mobile mote to the base station in a given time.  
The proposed protocol is implemented as TinyOS components, targeted for the 
MICA2 sensor network platform. Simulation results are presented that benchmark 
the proposed FAMA/TDMA Hybrid MAC against a CSMA based MAC (B-MAC) 
protocol as well as a demand assigned TDMA protocol. 
In addition to the above MICA2 motes were built locally for the purpose of testing 
the protocol on real hardware. A study was carried out and recommendation made 
on algorithms that can be used for data storage on such a system. 
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TABLE OF CONTENTS 
Title Page................................................................................................................ i 
Declaration............................................................................................................. ii 
Acknowledgement................................................................................................  iii 
Abstract.................................................................................................................. iv 
Table of Contents................................................................................................... v 
List of Figurers...................................................................................................... vi 
List of Tables......................................................................................................... vi 
List of Abbreviations............................................................................................ vii 
1.0 Introduction .............................................................................................................. 1 
2.0 Literature Survey ..................................................................................................... 3 
3.0 Methodology .......................................................................................................... 18 
4.0 Wireless Sensor Node Hardware ........................................................................... 20 
5.0 The MAC protocol ................................................................................................. 25 
6.0 Simulations & Results............................................................................................ 36 
7.0 Recommendations for data storage ........................................................................ 43 
8.0 Conclusion ............................................................................................................. 45 
References .................................................................................................................... 46 
Appendix A – The MICA2 V1 Schematic and PCB ...................................................... i 
Appendix B – The MICA2 V2 Schematic and PCB..................................................... iv 
 
 vi 
LIST OF FIGURES 
Figure 1.1 – Illustration of scenario under study ........................................................... 1 
Figure 2.1 – Classification of MAC protocols and some examples .............................. 4 
Figure 2.2 – Preamble sampling in LPL ........................................................................ 5 
Figure 2.3 – Comparison between LPL and X-MAC .................................................... 6 
Figure 2.4 – S-MAC sleep periods and active periods .................................................. 7 
Figure 2.5 – A graphical representation of the Blink application ................................ 14 
Figure 2.6 – Interface user and interface provider ....................................................... 15 
Figure 4.1 – A MPR4x0 aka MICA2 mote from Crossbow Technologies ................. 20 
Figure 4.2 – A block diagram of a MICA2 .................................................................. 20 
Figure 4.3 – The CC1000 plug and play radio module................................................ 21 
Figure 4.4 – The MICA2 V1 board with the plug and play radio module attached .... 22 
Figure 4.5 – A block diagram of a MICA2 V2 ............................................................ 22 
Figure 4.5 – The MICA2 V2 board with expansion modules attached ....................... 23 
Figure 5.1 – Process for MAC protocol development ................................................. 25 
Figure 5.2 – Transmission periods and contention periods ......................................... 26 
Figure 5.3 – Flow diagram of demand assigned TDMA MAC ................................... 27 
Figure 5.4 – Use of guard periods in the transmission period ..................................... 29 
Figure 5.5 – Efficient use of radio resources by repeated transmission ...................... 29 
Figure 5.6 – Flow diagram for the transmission period ............................................... 30 
Figure 5.7 – Packets exchanged during contention period .......................................... 31 
Figure 5.8 – Flow diagram for the contention period .................................................. 32 
Figure 5.9 – Flow diagram of FAMA/TDMA MAC ................................................... 34 
Figure 5.10 – Flow diagram of a transmission period for the FAMA/TDMA MAC .. 35 
Figure 6.1 – BMAC - Throughput vs Number of nodes .............................................. 38 
Figure 6.2 – FAMA/BMAC hybrid - Throughput vs Number of nodes ...................... 39 
Figure 6.3 – Demand assigned TDMA MAC - Throughput vs Number of nodes ...... 39 
Figure 6.4 – FAMA/TDMA hybrid - Throughput vs Number of nodes ...................... 40 
Figure 6.5 – Comparison of Simulation Results - Throughput vs Number of nodes .. 41 
LIST OF TABLES 
Table 2.1 – WSN platforms ........................................................................................... 3 
Table 2.2 – Flash file systems ...................................................................................... 12 
Table 2.3 – Some popular memory cards .................................................................... 13 
Table 2.4 – Open-source WSN operating systems ...................................................... 14 
Table 2.5 – Components of a TinyOS deployment...................................................... 16 
Table 2.6 – Motes that support TinyOS platform ........................................................ 16 
Table 4.1 – Standard sensor boards ............................................................................. 21 
Table 5.1 – Packets exchanged during the transmission period .................................. 28 
Table 5.2 – Packets exchanged during the contention period ...................................... 31 
Table 6.1 – Comparison between FAMA/BMAC & FAMA/TDMA MAC ............... 41 
Table 6.2 – Simulation verification for TDMA MAC ................................................. 42 
Table 6.3 – Simulation verification for FAMA/TDMA MAC .................................... 42 
 
 vii 
 
LIST OF ABBREVIATIONS 
 
API – Application programmers interface 
BMA – Bit-map-assisted 
B-MAC – Berkeley Medium Access Protocol 
CF – Compact flash 
COTS – Common off the shelf 
CPU – Central processing unit 
CSMA – Carrier sense multiple access 
CTS – Clear to send 
EEPROM – Electrically Erasable Programmable Read-Only Memory 
FAMA – Floor acquisition multiple access 
FAT – File allocation table 
FIFO – First-in-first-out 
GAMA – Group allocation multiple access 
GPRS – General packet radio service 
GPS – Global positioning system 
GUI – Graphical user interface 
IC – Integrated circuit 
IR – Infra-red 
LAN – Local area network 
LEACH – Low Energy Adaptive Clustering Hierarchy 
LED – Light emitting diode 
LMAC – Lightweight Medium Access Protocol  
LPL – Low power listening 
MAC – Medium/Media Access Control 
MEMS – Micro-Electro-Mechanical Systems 
MMC – Multimedia memory card 
MMU – Memory management unit 
OS – Operating system 
PCB – Printed circuit board 
 
…… continued 
 viii 
 
LIST OF ABBREVIATIONS  
 
PDA – Personal digital assistant 
PEDAMACS – Power efficient and delay aware medium access protocol sensor 
networks 
PPC – Packets-per-cycle 
RF – Radio frequency 
ROM – Read only memory 
RTS – Ready to send 
Rx  – Receiver/Reception 
SD – Secure Digital 
S-MAC – Sensor Medium Access Protocol 
S-MAC/AL – Sensor MAC with adaptive listening 
SPI – Serial peripheral interface 
SRAM – Static random access memory 
TDMA – Time division multiple access 
T-MAC – Timeout Medium Access Protocol 
TOSSIM – TinyOS simulator 
Tx – Transmitter/Transmission 
WSN – Wireless sensor network