Background
Both rare high-impact natural hazard events (e.g., hurricanes, flooding, tsunamis, etc.) and deliberate or accidental human actions (e.g., forest fires, terrorist incidents, radioactive fallout, etc.) are known to result in heightened risk to humans, private property and a nation’s critical infrastructure. By contrast, common routine emergency events (e.g., medical emergencies, road accidents etc.), are considered smaller scale emergencies in terms of the number of people or property affected, but still present a very significant risk due to their relatively high frequency of occurrence. For instance, the Helsinki capital region of Finland (population around 0.5 million) is classified as a relatively low risk area in terms of occurrence of hazard events (Schmidt-Thomé, 2006), but the medical emergency personnel in the same region still attend to over 40000 ambulance calls annually (Kuisma et al, 2009).
In both large and small scale emergencies, the utilization of public safety communication (PSC) solutions is essential for risk mitigation and preparedness prior to an emergency event, as well as, immediate response and long-term recovery operations after occurrence of the emergency event (Analysys Mason, 2010). Specifically, PSC enhances the interaction between (and among) citizens and authorities for improved situational awareness, rapid response and cooperation across emergency response domains, so as to, reduce the risk and minimize the impact associated with a particular emergency event. The term authorities in this context collectively refers to emergency first responders (e.g., fire-fighters, police, paramedics etc.), emergency control centres, Public Safety Answering Points (PSAP), local administration, or any other organization with the responsibility of providing services that ensure safety and security of citizens who are under risk or affected by an emergency event.
To that end, PSC facilitates information flow by enabling the following interactions (also illustrated in Figure 1):
Figure 1. PSC interactions between (and among) citizens and authorities
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Communication from citizens to authorities, typically initiated by citizens as emergency calls by dialling 1-1-2, 9-1-1 or 9-9-9;
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Communication between authorities, for instance, between mobile field units (e.g., ambulances, fire engines, police patrol units etc.) and emergency command and control centres;
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Communication from authorities to citizens, usually implemented as government or commercial emergency alerting services, such as, mobile text messages and automated voice call alerts disseminated to citizens under risk to warn of an impending hazard event;
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Communication between citizens during emergencies, enabling victims and relatives or friends to stay in contact during or after an emergency.
Inability to communicate and share information effectively or reliably in the cases described above may undermine emergency response operations; result in unnecessary panic and exert further pressure on limited authority resources. Therefore, reliability and service availability are paramount considerations for communication infrastructure and services intended for PSC purposes.
The increased uptake of rich multimedia solutions in emergency operations adds value to the aforementioned interactions, enhances information sharing for improved situational awareness, and also boosts operational efficiency of authority personnel. However, the innovative multimedia solutions also place increased demands in terms of stringent quality-of-service guarantees and resource requirements on the underlying network infrastructure.
Contemporary Public Land Mobile Networks (PLMNs) now provide flexible tetherless connectivity, wide-area coverage and increasingly higher throughputs, and are generally considered to be essential for PSC within and between authority organizations (Analysys Mason, 2010; Ericsson, 2010). However, the achievable performance (e.g., throughput, packet loss, etc.) in broadband macrocellular PLMNs is typically limited in practice, as it depends on network load, user location relative to cell site, radio channel conditions, interference, building attenuation, and so on (Holma & Toskala, 2007; Holma & Toskala, 2009).
Femtocells have been introduced as an attractive solution for coverage enhancement, innovative local area service delivery and overall Quality of Experience (QoE) improvement for PLMN subscribers in indoor environments and selected outdoor locations, without the need for costly upgrades to the existing macrocellular network (Chandrasekhar & Andrews, 2008; Chiussi, et al., 2009; Zhang & de la Roche, 2009). This Chapter analyzes how residential femtocells deployed autonomously by subscribers could be leveraged to support rich multimedia communications for PSC use case scenarios, with a particular focus on authority-to-authority communications.