Nessum

Nessum is a communication technology standardized by the Institute of Electrical and Electronics Engineers (IEEE). It is standardized as IEEE 1901-2020. The standard be used to communicate data over wired, wireless media using high frequencies (kHz to MHz bands). The Nessum Alliance is a certifying body for compatibility between Nessum-based communication devices.

Overview
Nessum has two types of communication: wired (Nessum WIRE) and wireless (Nessum AIR).

Wired communication
Nessum WIRE can be used for various types of lines such as power lines, twisted pair lines, coaxial cable lines, and telephone lines. The communication distance can range between tens of meters to various kilometers depending on the use case. In addition, when an automatic relay function called multi-hop (ITU-T G.9905) is utilized, a maximum of 10 stages of relay is possible. With a maximum physical speed of 1 Gbps and effective speeds ranging from several Mbps to several tens of Mbps, this technology is used to reduce network construction costs by utilizing existing lines, to increase the speed of low-speed wired communication lines, to supplement wireless communication where it cannot reach, and to reduce the number of lines in equipment.

Wireless communication
Short range wireless communication called Nessum AIR. It uses magnetic field communication in the short range, and the communication distance can be controlled in the range of a few centimeters to 100 centimeters. Maximum physical speed is 1 Gbps, with an effective speed of 100 Mbps.

Physical layer (PHY)
The physical layer uses Wavelet OFDM (Wavelet Orthogonal Frequency Division Multiplexing). While a guard interval is required in ordinary OFDM systems, the Wavelet OFDM system eliminates the guard interval and increases the occupancy rate of the data portion, thereby achieving high efficiency. In addition, due to the bandwidth limitation of each subcarrier, the level of sidelobes is set low, which facilitates the formation of spectral notches. This minimizes interference with existing systems and allows for flexible compliance with frequency utilization regulations. Furthermore, Pulse-Amplitude Modulation (PAM) is used for each subcarrier, and the optimal number of modulation multi-levels is set according to the conditions of the transmission path, thereby improving transmission efficiency. The frequency band used can be selected from among standardized patterns.

Data link layer (MAC)
The data link layer manages Quality of Service (QoS) and other control functions using control frames "beacons" broadcast periodically by the parent to all terminals in the network. The basic media access methods are Carrier-Sense Multiple Access with Collision Avoidance (CSMA/CA) and Dynamic Virtual Token Passing (DVTP), which dynamically assign transmission rights to terminals in the network and avoid collisions, The system uses a collision avoidance mechanism.

Nessum Alliance
Nessum Alliance was established in September 2007 as a voluntary association, originally under the name of "HD-PLC Alliance". In October 2023, the HD-PLC Alliance was renamed the Nessum Alliance.

History
This technology is based on HD-PLC, a type of power line communication developed by Panasonic in the early 2000s. HD-PLC was developed for room-to-room transmission of TV images at the time, but later began to be used not only for power lines but also for coaxial lines and twisted pair lines, and even for wireless communication. The name "power line communication" did not match the reality of the situation. In September 2023, Panasonic Holdings Corporation changed the name of HD-PLC to Nessum.