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Cellular IoT -- short-range radio solutions: Wi-Fi

Olof Liberg, Marten Sundberg, Eric Wang, Johan Bergman, Joachim Sachs

August 28, 2018

Olof Liberg, Marten Sundberg, Eric Wang, Johan Bergman, Joachim SachsAugust 28, 2018

9.1.2.1.4 Capillary Networks

Short-range radio technologies provide the ability to build out connectivity efficiently to devices within a specific local area. Typically, these local—or capillary—networks need to be connected to the edge of a wide area communication infrastructure so that they have the ability, for example, to reach service functions that are hosted somewhere on the Internet or in a service cloud.

A capillary network needs a backhaul connection, which can be well provided by a cellular network. Their ubiquitous coverage allows backhaul connectivity to be provided practically anywhere, simply and, more significantly, without additional installation of network equipment. Furthermore, a capillary network might be on the move, as is the case for monitoring goods in transit, and therefore cellular networks are a natural solution. To connect a capillary network through a cellular network, a gateway is used between the cellular network and the capillary network, which acts just like any other cellular device towards the cellular network.

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FIGURE 9.6 Capillary networks.

Figure 9.6 illustrates an architecture, which comprises three domains: the capillary connectivity domain, the wide-area connectivity domain, and the data domain. The capillary connectivity domain spans the nodes that provide connectivity in the capillary network, and the wide-area connectivity domain spans the nodes of the cellular network. The data domain spans the nodes that provide data processing functionality for a desired service. These nodes are primarily the connected devices themselves as they generate and use service data through an intermediate node, such as a capillary gateway. The capillary gateway would also be included in the data domain if it provides data processing functionality (for example, if it acts as a CoAP mirror server).

All three domains are separate from a security perspective, and end-to-end security can be provided by linking security relationships in the different domains to one another.

The ownership roles and business scenarios for each domain may differ from case to case. For example, to monitor the in-building sensors of a real estate company, a cellular operator might operate a wide-area network and own and manage the capillary network that provides connectivity to the sensors. The same operator may also own and manage the services provided by the data domain and, if so, would be in control of all three domains.

Alternatively, the real estate company might own the capillary network, and partner with an operator for connectivity and provision of the data domain. Or the real estate company might own and manage both the capillary network and the data domain with the operator providing connectivity only.

In all these scenarios, different service agreements are needed to cover the interfaces between the domains specifying what functionality will be provided.

In large-scale deployments, some devices will connect through a capillary gateway, while others will connect directly. Regardless of how connectivity is provided, the bootstrapping and management mechanisms used should be homogenic to reduce implementation complexity and improve usability.

A more extensive discussion of IoT connectivity via capillary networks can be found in Reference [44].

The next installment addresses long-range radio solutions.

Reprinted with permission from Elsevier/Academic Press, Copyright © 2017

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