# Implementation of a Topology Independent MAC (TiMAC) Policy on a Low-Cost IoT System

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## Abstract

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## 1. Introduction

## 2. Past Related Work

## 3. The TiMAC Policy

## 4. The Proposed System

#### 4.1. Low-Cost Devices

#### 4.2. Message Types

`SYNC`messages.

`SYNC`messages are transmitted by all network nodes at the beginning of each frame, for time synchronization purposes. The payload of

`SYNC`messages “carries” the time remaining until the first time slot begins. The second type of messages contains the

`DATA`messages. By the time a network node has data ready for transmission, it constructs a

`DATA`message that contains the data to be sent. The next step is to transmit the DATA message during the particular node’s time slot. The existence of these two distinct message types is necessary for the smooth operation of the TDMA protocol. At the beginning of each frame, all nodes exchange and process

`SYNC`messages in order to achieve synchronization of the receiver’s TDMA clock timer.

`DATA`messages, carrying the valuable information nodes are supposed to send, are transmitted by the network nodes during the particular time-slots that have been assigned to them.

#### 4.3. TDMA Parameters

#### 4.4. Synchronization

## 5. Experimental Methodology and Results

#### 5.1. Methodology

#### 5.2. Results

## 6. Conclusions

## Author Contributions

## Funding

## Acknowledgments

## Conflicts of Interest

## Abbreviations

MAC | Medium Access Control |

TDMA | Time Division Multiple Access |

IoT | Internet of Things |

TiMAC | Topology independent Medium Access Control |

CSMA | Carrier Sense Multiple Access |

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**Figure 3.**The wiring between the Arduino and the RF modules that implements the device for both transmission (i.e., Tx-module data connected to pin 12) and reception (i.e., Rx-module data connected to pin 12). The antenna (ANT) along with the power supply pins (i.e., GND and VCC) are also depicted.

**Figure 4.**The TDMA frame of the implemented MAC protocol. Each time slot (ts${}_{i}$) ends with the guard period (t${}_{g}$). The synchronization time (st) along with the frame guard period (t${}_{fg}$) are also depicted.

**Figure 5.**Illustration of the synchronization mechanism within a synchronization period (st), among nodes r, u and v connected in a chain topology. Nodes wait for a certain amount of time (i.e., ${t}_{dr}$, ${t}_{du}$ and ${t}_{dv}$, respectively) before transmitting the time remaining until the first time slot (i.e., ${t}_{0}$, ${t}_{1}$ and ${t}_{2}$, respectively). The internal clocks ${c}_{u}$, ${c}_{v}$ along with the transmission time ${t}_{tx}$ are also depicted.

**Figure 6.**Throughput corresponding to various polynomial sets. In all cases, the throughput lays between the expected maximum (i.e., $0.2$) and minimum (i.e., $0.04$) values.

**Figure 7.**Average number of successful transmissions per frame per node corresponding to various polynomial sets. In all cases, the number of successful transmissions is between the expected maximum (i.e., 5) and minimum (i.e., 1) values.

Polynomial Set | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 |
---|---|---|---|---|---|---|---|---|---|---|---|

Node A | 0x + 0 | 1x + 2 | 0x + 1 | 0x + 4 | 1x + 0 | 0x + 1 | 0x + 3 | 0x + 1 | 0x + 2 | 0x + 1 | 2x + 1 |

Node B | 0x + 1 | 1x + 3 | 0x + 4 | 1x + 1 | 1x + 3 | 0x + 4 | 1x + 0 | 0x + 2 | 0x + 3 | 2x + 0 | 2x + 4 |

Node C | 0x + 2 | 2x + 0 | 2x + 0 | 1x + 2 | 1x + 4 | 2x + 2 | 2x + 4 | 0x + 4 | 2x + 4 | 2x + 3 | 3x + 0 |

Node D | 0x + 3 | 2x + 2 | 2x + 2 | 2x + 0 | 3x + 3 | 3x + 3 | 3x + 1 | 1x + 0 | 3x + 2 | 2x + 4 | 3x + 4 |

Node E | 0x + 4 | 3x + 0 | 2x + 3 | 3x + 2 | 4x + 4 | 4x + 4 | 4x + 4 | 4x + 1 | 4x + 1 | 4x + 1 | 4x + 2 |

Polynomial Set | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 |
---|---|---|---|---|---|---|---|---|---|---|---|

Node A | 495 | 203 | 101 | 100 | 301 | 200 | 100 | 300 | 298 | 98 | 202 |

Node B | 423 | 399 | 200 | 101 | 300 | 199 | 102 | 200 | 201 | 194 | 300 |

Node C | 500 | 193 | 258 | 398 | 400 | 300 | 200 | 206 | 200 | 400 | 198 |

Node D | 396 | 275 | 302 | 99 | 198 | 200 | 200 | 97 | 198 | 195 | 200 |

Node E | 396 | 102 | 398 | 99 | 99 | 200 | 200 | 99 | 102 | 195 | 200 |

Total | 2210 | 1172 | 1259 | 797 | 1298 | 1099 | 802 | 902 | 999 | 1082 | 1100 |

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## Share and Cite

**MDPI and ACS Style**

Tsoumanis, G.; Papamichail, A.; Dragonas, V.; Koufoudakis, G.; Angelis, C.T.; Oikonomou, K.
Implementation of a Topology Independent MAC (TiMAC) Policy on a Low-Cost IoT System. *Future Internet* **2020**, *12*, 86.
https://doi.org/10.3390/fi12050086

**AMA Style**

Tsoumanis G, Papamichail A, Dragonas V, Koufoudakis G, Angelis CT, Oikonomou K.
Implementation of a Topology Independent MAC (TiMAC) Policy on a Low-Cost IoT System. *Future Internet*. 2020; 12(5):86.
https://doi.org/10.3390/fi12050086

**Chicago/Turabian Style**

Tsoumanis, Georgios, Asterios Papamichail, Vasileios Dragonas, George Koufoudakis, Constantinos T. Angelis, and Konstantinos Oikonomou.
2020. "Implementation of a Topology Independent MAC (TiMAC) Policy on a Low-Cost IoT System" *Future Internet* 12, no. 5: 86.
https://doi.org/10.3390/fi12050086