Experimenting Opportunistic Networks with WiFi Direct{Marco Conti, Franca Delmastro, Giovanni Minutiello, Roberta Paris}

Instructor:Prof. Carla-Fabianna Chiasserini

Student

Zegeye, Wondimu K.

Master univ. di II livello in Future Broadband Networks (2013/14 A.Y.)Advanced Wireless Networks: Literature

Review

Institute of Informatics and Telematics (IIT)National Research Council of Italy, Pisa

Outline• Introduction to Opportunistic Networks• WiFi Direct Overview

Device Discovery and Group Formation Android and WiFi Direct

• Experimental Setups• Experimental Results• Conclusions

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Opportunistic Networks

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In an Opportunistic Network,• Nodes are mobile/fixed.• Communication possible even if no

connecting route exists between nodes.• Routes are built dynamically- i.e.,

communication path not predetermined.• For the next hop, a node would be

opportunistically chosen only if it would bring the message closer to final destination.

• Initial implementations relied on WiFi ad-hoc mode which are not able to manage infrastructure d communication.

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WiFi Direct Overview

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•WiFi Direct, initially called Wi-Fi P2P currently the referenced standard to support device-to-device (D2D) Communication on WiFi channels.•Available in different mobile platforms

Android 4.2(Jelly bean), Windows 8.1•WiFi-Direct devices communicate by establishing groups assuming the roles of Group Owner (GO) and/orClient.•Device discovery involves Find and Scan phases in which P2P devices alternate search and listen states.•Group Formation following the device discovery involves identifying the GO,CLIENTs and establishing connection.

Device Discovery and Group

Formation• WiFi Direct defines three different procedures for group

formation. Standard: GO negotiation through a three-way handshake. Autonomous: node elects itself as GO and announces its

presence via beacon. Persistent: nodes can use their local information to

rebuild.

• Authentication procedure based on WiFi Protected Setup (WPS) mainly based on PIN code exchange once the GO is identified .

• Address configuration Phase : DHCP running on the GO.

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Discovery and Group Formation

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• Devices can be either GO or CLIENT GO: acts as a SoftAP CLIENT: associates itself to the GO and if it is legacy WiFi

client it doesn’t belong to the group but they still consider the GO as an AP.

• WiFi-Direct does not allow the transfer of GO role within a group.

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Android and WiFi Direct

• WiFiP2P API of Android internally managed by WiFi Direct framework, wpa_supplicant process .

• wpa_supplicant maintains p2p_supplicant.conf file which stores local device’s parameters and information.

• WiFiP2P APIs allows mobile applications to discover, request information, and connect to other peers be notified of the success or failure of the previous

operations register intents that notify the application of specific

events detected by the framework through networking operations

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Two-Nodes Standard Group Formation

8Zegeye,Wondimu Kassahun Standard group formation

Two-Nodes Standard Group Formation

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P2P Standard Group Formation

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Camps-Mur, Garcia-Saavedra, Serrano, “Device to device communications with wifi direct: overview and experimentation”, IEEE Wireless Communications Magazine, 2012

Two nodes experiment : discovery and

group formation delays

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autonomous: 1s,persistent [1.48s,15.35s] standard[1.5s,15.9s]

autonomous: 3s (92%) + 5s(8%)standard: avg=12.26s, 9.5% (WPS) , 3.5%(others)

standard: Worst case 23spersistent and standard: 20%(higher times

Three Nodes Simultaneous Group Formation

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Three Nodes Simultaneous Group

Formation

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Three Nodes Experiment

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Times and errors during the three-nodes experiments.

Incremental Group Formation

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• Instead of devices simultaneously trying to form a group and incremental group formation is more realistic.

• In this experiment, 6 Nodes which incrementally join the group with a 150s delay in between them.

Incremental Join Procedure

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(A /B) includes the GO negotiation procedure

Conclusions

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• Experimental results shows the complexity of WiFi Direct to manage a variable number of nodes joining the same group for deploying opportunistic networks in a large scale.

• Dynamic parameters (such as nodes’ mobility, heterogeneous devices) should be considered for opportunistic networks.

• WiFi Direct integration with CAMEO (Context-Aware Middleware for Opportunistic Networks).

• By exploiting information related with the user and his/her device, WiFi Direct can pave a way for large scale Mobile Social Networks (MSN).

Thank you! for your kindAttention.

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