The “Language” of Smart Meters

Language is an indispensable element of human society and serves as a bridge for interpersonal communication. Different regions and countries have diverse languages, each with unique charms and functions. Today we will talk about the “language” of smart meters — communication methods.

IR communication (Infrared Communication) is one type of wireless communication, suitable for low cost, point to point data connections. During communication, the transmitting end modulates base band binary signals into a series of pulse train signals, which are emitted via infrared emitting diodes. The receiving end converts the received infrared light pulses into electrical signals. After amplification, filtering and other processing, the signals are sent to the demodulation circuit for demodulation, and restored into binary digital signals for output. It features fast transmission speed, short communication range, high security and wireless transmission.

RS485 communication addresses the drawbacks of RS232 applied to smart meters, such as short communication distance, low transmission rate, common ground noise and poor common mode interference rejection. RS485 adopts differential transmission, also known as balanced transmission, using two twisted pair wires, conventionally designated as A and B. Logic “1” is represented by a voltage difference of +(2 6) V between the two wires; logic “0” is represented by a voltage difference of −(2 6) V. Its interface signal level is lower than that of RS 232 C, so interface circuit chips are less vulnerable to damage. The level is compatible with TTL level, enabling convenient connection with TTL circuits.

NB IoT communication for smart meters is based on Narrow Band Internet of Things (NB IoT), an important branch of the Internet of Everything. Built upon cellular networks, NB IoT consumes a bandwidth of approximately 180 kHz. It can be directly deployed on GSM, UMTS or LTE networks to reduce deployment costs and achieve smooth upgrades. Targeting the Low Power Wide Area (LPWA) IoT market, NB IoT is an emerging technology for global wide deployment. Its characteristics include extensive coverage, massive connections, low data rate, low cost, low power consumption and optimized architecture. Operating on licensed frequency bands, NB IoT supports three deployment modes: in band, guard band and standalone carrier, enabling coexistence with existing networks.

LoRa is the abbreviation for Long Range, a low power wide area network communication technology. It is an ultra long range wireless transmission solution based on spread spectrum technology, adopted and promoted by Semtech Corporation of the United States. The advent of LoRa wireless technology has changed the trade off between transmission distance and power consumption for smart meters. It realizes long distance transmission while delivering low power consumption, multi node capacity and low cost.

Power Line Communication (PLC) is a communication method that transmits data and media signals over power lines. In PLC, original signals are modulated into high frequency signals and coupled onto power lines for transmission. At the receiving end, modulated signals are extracted by filters and demodulated to recover the original signals for information exchange. It is characterized by fast transmission speed, wide coverage, energy saving performance and high safety.

GPRS stands for General Packet Radio Service, a 2.5G technology between the second generation and third generation mobile systems. GPRS introduces two new network nodes into the original circuit switched (CSD) GSM network: the Serving GPRS Support Node (SGSN) and the Gateway GPRS Support Node (GGSN). At the same hierarchical level as the MSC, the SGSN maintains storage records for individual mobile stations to implement security functions and access control, and connects to base station systems via Frame Relay. The GPRS network offers wide coverage, fast data transmission, high communication quality, always on connectivity and data volume based billing. As a packet switched data network supporting the TCP/IP protocol, it can interconnect directly with the Internet without geographical restrictions.