In several emergency situations, during natural or human-caused disasters, frontline responders need to be able to communicate and collaborate to properly carry out relief missions. Some countries build their national Public Safety Mobile Broadband based on cellular LTE technology to provide fast, safe, and secure emergency services. However, in several emergency situations, cellular antennas can be overloaded or partially damaged in a manner that affects group communication services. In the last few years, direct device-to-device (D2D) communications have been proposed by the 3GPP as an underlay of long-term evolution (LTE) networks based on proximity, reuse, and hop gains. This paper focuses on a loosely coupled model based on direct D2D communication in a public safety context. Many scenarios related to user membership and network management are detailed. Both the “less cost” and “optimized tree” approaches are proposed and implemented, and their performance is evaluated in terms of the network update number and the resulting average Channel Quality Indicator (CQI). Other optimization approaches, with different CQI thresholds and optimization interval parameters, are simulated to compare their performance with the “optimized tree” approach. By conducting simulations that combine a CQI threshold = 1 and optimization interval = 2 s, it becomes possible to keep an average CQI level close to the “optimized tree” approach, while the costs related to network updates significantly decrease by almost 35%. Other simulations are also carried out to measure the bandwidth required by the control messages between the server and active users. It was found that both inbound and outbound traffic on the server side can be well supported with LTE and 5G networks.

In public safety scenarios, communication between responders is crucial to ensure better cooperation during rescue missions. Several Mission critical services have been proposed by 3GPP, enabling the exchange of data, voice, and multimedia content over the latest generation of cellular networks. Despite the great popularity of cellular technologies, there are limitations when users exchange large amounts of data traffic at the edge of the antenna. By taking advantage of the proximity between users, deploying Device-to-Device (D2D) communication should offer better bandwidth, lower delays, and optimized device energy consumption. To overcome the range limitations of Direct D2D communication, a multi-hop cooperative relay based on CQI (Channel Quality Indicator) can route the message to the final destination. Two communication modes are thus proposed: (1) the D2D Loosely Coupled mode, which relies exclusively on user-type relays, and (2) the Hybrid mode, which allows the cellular antenna to be used as a relay when routing packets. This paper proposes modeling and evaluation of these solutions in the context of rescue operations, using an extension of the Simu5G library under the OMNeT++ simulator. Several configurations, including different application bitrates, showcase the coverage capabilities and related end-to-end delays when using a multi-relays solution compared to Direct D2D communication. The D2D Loosely coupled and Hybrid modes are evaluated and compared to the Infrastructure mode, particularly when traffic moves to the edge of the cell. Hybrid mode performance has been highlighted through a series of mobility scenarios.

In several emergency situations, during natural or human-caused disasters, frontline responders need communication and collaboration infrastructure to properly carry out the relief mission. Some countries are building their national Public Safety Mobile Broadband based on cellular L TE technology to provide fast, safe, and secure emergency services. Otherwise, in several emergency situations, the cellular antennas can be overloaded or partially damaged in manner to affect the group communication services. Since few last years, direct device-to-device (D2D) communications have been proposed by 3GPP as an underlay to Long Term Evolution (L TE) networks based on proximity, reuse, and hop gains. This paper focuses on the loosely coupled model based on D2D direct communication for Public Safety context. Many scenarios related to user membership and network management are detailed. Both “less cost” and “optimized tree” approaches are proposed, implemented, and their performance evaluated in terms of network updates number and resulting average Channel Quality Indicator (CQI). Other optimization approaches, with different CQI threshold and optimization interval parameters, have been simulated to compare their performance with the “optimized tree” approach.

Some IP-phones are offering only a simple user interface with plain DTMF digits and optional function buttons, but without any graphical display. This kind of limited user interface makes cumbersome the usage of advanced IP-telephony services in many scenarios. Enhancing IP-telephony services with collaborative devices can both resolve the capabilities limitations of IP-phones and also encourage user location mobility. The introduced solution consists of using a third party device, such as a PC on an IP network, to make a connection with the IP-phone where the connection is realised with a specific protocol based on the session initiation protocol (SIP); this protocol benefits from the subscribe/notify mechanism defined by the IETF. By exchanging notify requests and by using suitable information encoding, the two devices are able to collaborate and can evolve together to carry out advanced IP-telephony services. On the scope of this work, some collaborative services such as the caller-id service were analysed, developed and implemented

New services based on session initiation protocol (SIP) signaling, such as videoconferencing and presence-based applications, are emerging. New services mean new sets of requirements which, in turn, mean that existing architectures or protocols are not always adequate. A concrete example of such a new service is a system enabling an ambulance attendant to communicate with a number of physicians at the same time. In addition to regular voice transmission, the conference thus established would allow participants to study a patient's biometric data and share annotations directly. After formalizing the new set of requirements this service calls for, we turned to the most common mechanisms available and found that there are none perfectly suited to this new application. We therefore considered a less well-known mechanism, which is based on SIP and the implementation of a full mesh topology. This solution provides strong reliability, easy integration in future SIP user agents, powerful security capabilities and other essential features. ecgML, an innovative open XML-based format developed for the storage and transmission of electrocardiograms (ECGs), was analyzed and integrated into the proposed solution for the transmission of the patient's biometric data

In several emergency situations, during natural or human-caused disasters, frontline responders need to be able to communicate and collaborate to properly carry out the relief mission. Some countries are building their national Public Safety Mobile Broadband based on cellular LTE technology to provide fast, safe, and secure emergency services. Otherwise, in several emergency situations, the cellular antennas can be overloaded or partially damaged in manner to affect the group communication services. Since few last years, direct device-to-device (D2D) communications have been proposed by 3GPP as an underlay to Long Term Evolution (LTE) networks based on proximity, reuse, and hop gains. This paper focuses on the loosely coupled model based on D2D direct communication for Public Safety context. Many scenarios related to user membership and network management are detailed. Both “less cost” and “optimized tree” approaches are proposed, implemented, and their performance evaluated in terms of network updates number and resulting average Channel Quality Indicator (CQI). Other optimization approaches with different CQI threshold and optimization interval values have been implemented, simulated and their performance are compared with the “optimized tree”.