# Smart Meter Gateways: Options for a BSI-Compliant Integration of Energy Management Systems
## 5 Options for a BSI-Compliant Integration of EMS into Smart Metering Systems  
As outlined before, it can be distinguished between the three network areas LMN, HAN, and WAN. The LMN is only used for the communication between the SMGW and meters. Hence, an EMS could be placed either locally in the HAN or remotely in the WAN. Inside the WAN, access to measurements is restricted to the data provided by the TAFs described above. Inside the HAN, access to fine-grained measurements is possible via the _Consumer Interface_ which provides access to all measurement readings. In this section, the options for integrating an EMS into the SMGW architecture are illustrated. We categorize the EMS integration options into two major classes:  
1. a full integration which uses the SMGW for both the collection of meter measurements and the transparent data tunnel; and
2. a partial integration, which only uses the SMGW for the transparent data tunnel and relies on an additional measurement collector for the collection of meter measurements. For the consumer using an EMS, the major benefit of a full integration is the fact that SMGW-established data tunnels between EMPs and local entities are always cryptographically secured based on the public-key infrastructure with X.509 certificates managed by the BSI [9]. Additionally, when relying on the SMGW architecture, passive EMPs (that are receiving meter-based data only) are required to provide a security concept, and active EMPs (that are interacting with CLSs) additionally require a certification according to the information security standard ISO/IEC 27001 [8]. Consequently, the use of SMGW-established data tunnels is beneficial for consumers who want to secure their data. However, the complexity is increased whenever an EMP is required, since either a contract with an existing EMP is needed or a certification in order to become an EMP has to be undergone. This is especially relevant to EMS providers who want to offer EMSs using the data tunnel to connect to the respective provider's remote services. After the following introduction of different options for the two introduced classes, the upcoming Section 6 provides an in-depth discussion of their specific pros and cons. Full Integration Using the SMGW for the Collection of Meter Measurements and the Transparent Data Tunnel  
First, we present options for a full integration that utilizes the SMGW for both the collection of meter measurements and the data tunnel between the HAN and the WAN. The regions outlined by the dashed blue boxes in Figure 2 show the three basic options for a full EMS integration:  
1. [label=_Option_ 1a_]
2. is a local EMS inside the HAN (with no access to the WAN). It has the exclusive control over one or more CLSs. Meter measurements are collected from the HAN interface, i.e., the _Consumer Interface_, and additional information may be provided by the CLSs. Both information sources can be used for an optimization that results in signals to the CLSs, hence influencing their behavior. 3. depicts the control of one or more CLSs by a remote EMS, i.e., an EMS located in the WAN. Using the mechanisms for accessing metering data provided by the technical guideline, a remote EMS can only retrieve metering data from the EMP. Hence, the EMS needs to either be part of the EMP's systems, or an interface between the EMP and the remote EMS is required. The meter measurements (or derived data) that are sent to the EMP, as well as the point in time when they are sent, is defined by the configured TAF (see Table 1). Based on remotely received data, the remote EMS uses the transparent data tunnel provided by the SMGW to send signals to control the CLSs inside the HAN. The data tunnel can be held open once it is established, however, a re-establishing may be required given certain events such as a loss of connection. * is a combination of both _Option 1a_ and _Option 1b_. A local EMS controls one or more CLSs but also shares information with a remote EMS (e.g., a regional EMS).