## 2 Architecture of the Multi-Communication-Based DR System  
The framework of the proposed multi-communication-based DR system is shown in Figure 1. This system could provide a wide-scale load aggregation service via IoT and existing internet connections. With appropriate strategies, this system can undertake time- and target-varying tasks.  
Figure 1: The framework of the multi-communication demand response (DR) system.  
To develop the proposed DR system, the following elements should be introduced into the existing power system:  
(a) Grid side--electric utility platform (UP) and demand response automatic server (DRAS)  
Electric utilities are the sponsors, owners, and benefit providers of the DR business. Therefore, the purpose of the UP is to call available DR resources to assist with grid control tasks. The monitoring and control scope of UP could be extended and restrained to the load aggregators (LAs), in order to ensure enough information with respect to the privacy of customers.  
DRAS is the central block of the DR system and acts as a bridge between the grid side and the customer side. On the grid side, DRAS provides the DR operating environment and functions to the UP by virtualizing DR resources. On the customer side, DRAS acts as the dispatcher, responsible for receiving real-time data from LAs and organizing corresponding LAs to complete DR tasks.  
(b) Customer side--multi-level agents, including load aggregators (LAs) and a home energy management system (HEMS)  
LAs provide a lower-level load aggregator function which could be seen as the implementation of DRAS near the customer side. Functions like data storage and resource organizing are also needed in LAs though simpler. Moreover, it comes with additional features to facilitate automation. The load operating data uploaded by LAs to the DRAS must be processed to retain only critical and holistic information. This measure is not only requested to protect local privacy, but also beneficial for decreasing the pressure on DRAS about data receiving, storing, managing, and processing. It should be noted that LAs can be divided into more levels according to the system scale.  
The HEMS has a similar function to LA, while the management scale is narrowed in a building or a home. Unlike the implementation of DRAS and LA needing professional servers, HEMS can be realized through an embedded processor and small local storage or cloud storage, which can be integrated with other functions in the body of a home intelligent gateway (HIG). Specially, the HEMS needs to respond to the instructions from both upper agents and customers, which acts like a smart manager for the latter.  
(c) Terminal--a novel DR smart terminal  
The smart terminals should be connected to the actual loads directly to collect or control their states. A novel DR smart terminal is also studied in this paper to support the functions of the proposed DR system, such as load aggregating, remote control, and quick DR tasks.  
The rest of this section describes the technologies and designs applied to the UP, DRAS, and agents, which enables the proposed system to undertake tasks with diverse characteristics simultaneously. Details about the design of the smart terminal are provided in Section 3.