Section: New Results

Opportunistic and local communication/information sharing

Participants : Yoann Maurel, Jules Desjardin, Paul Couderc [contact] .

Smart spaces (Smart-city, home, building, etc.) are complex environments made up of resources (cars, smartphones, electronic equipment, applications, servers, flows, etc.) that cooperate to provide a wide range of services to a wide range of users. They are by nature extremely fluctuating, heterogeneous, and unpredictable. In addition, applications are often mobile and have to migrate or are offered by mobile platforms such as smartphones or vehicles. To be relevant, applications must be able to adapt to users by understanding their environment and anticipating its evolutions. Communication between devices and information sharing is a key to achieve this goal. In recent years, many products have been developed based on the cloud. This raises privacy and network access issues.We believe that communication and information sharing should be able to take place directly when possible, more efficient, confidential, or when the network is not available. To achieve this, applications must be provided with technologies that enable the opportunistic and rapid exchange of information based on simple and widespread technologies.

Applications such as pervasive games (for ex. Pokemon Go), on the go data sharing, collaborative mobile app are often good candidates for opportunistic or dynamic interaction models. But they are not well supported by existing communication stacks, especially in context involving multiple technologies. Technological heterogeneity is not hidden, and high level properties associated with the interactions, such as proximity/range, or mobility-related parameters (speed, discovery latency) have to be addressed in an ad hoc manner.

We think that a good way to solve these issues is to offer an abstract interaction model that could be mapped over the common proximity communication technologies, in a similar way as MOM (Message Oriented Middleware) such as MQTT abstract communications in many IoT and pervasive computing scenarios. However, they typically requires IP level communication, which far beyond the capabilities of ultra low energy proximity communication such as RFID and BLE. Moreover, they often rely on a coordinator node that is not adapted in highly dynamic context involving ephemeral communications and mobile nodes.

To ease communication, we developed an opportunistic communication system that does not need any connection between participants, nor any preexisting infrastructure (e.g. WiFi network). The only condition for participants to exchange information is that they are close enough to each other. The communication protocol has been implemented over Bluetooth Low Energy advertisement packets. This protocol has been ported to ESP8266, ESP32 and Android platform. To ease information sharing, we started the implementation of an associative memory mechanism over BLE, as it is a common ground that can be shared with passive or semi passive communications (RFID, NFC). Such mechanism, although relatively low level, is still a very useful building block for opportunistic applications: it enables opportunistic data storage/sharing and signaling/synchronization (in space in particular). This approach is fully in line with more general trend developed in the team to build smart systems leveraging local resources and data oriented mediation. The communication protocol has been extended to allow REST-like operations. The implementation in C of the protocol and a storage base was done in such a way as to take little memory and run on small chips (ESP8266, ESP32). The storage base can be accessed either opportunistically using the BLE protocol or via a COAP protocol for longer or bigger exchanges.

We have started validation work with a few applications, in particular regarding energy aspects and scalability with respect to the communication load. We also tested the system for building opportunistic games (e.g, capture the flags) and information sharing mechanism (e.g, sharing information when two devices cross paths). We are currently working on structuring knowledge information in the continuity of what has been done in the team in the past and provide encryption mechanism.

This should lead to publishing on both infrastructure and application level aspects of the approach.