Originally designed for reliable data transmission over noisy power lines, Nessum (formerly HD-PLC) is now evolving to support a broader range of communication infrastructures, including twisted-pair networks.

Challenges in Power Line Communication

Communicating over power lines presents several major challenges:

• Noise Interference – Electrical devices generate various types of noise that can disrupt communication.
• Signal Reflection – The flexibility of power line connections causes complex signal reflections, leading to frequency-selective fading.
• High Attenuation – Power circuits have very low impedance, often just a few ohms, resulting in over 10 dB of signal loss.

Without advanced modulation and error correction, reliable communication under these conditions would be nearly impossible.

Nessum’s Advanced Solutions

To address these challenges, Nessum integrates state-of-the-art technologies that ensure exceptional robustness in harsh environments.

The following figure shows the block diagram of the Nessum SoC.

• Transmission (TX): The sending packet is queued in the Nessum MAC, which manages retries, data concatenation, QoS, and other functionalities. The packet is then transferred to the Nessum PHY, where it undergoes LDPC-CC encoding, data mapping, and modulation via inverse OFDM. The modulated digital data is converted to analog by the ADC in the AFE and transmitted to the network.
• Reception (RX): The received signal is amplified and converted to digital data by the DAC in the AFE. The digital data is then demodulated via an OFDM demodulator, equalized, and error-corrected by FEC. Based on the error correction result, the Nessum MAC sends either an ACK or NACK and reconstructs the packet.

 

– LDPC-CC Forward Error Correction (FEC) and Retry Mechanism

This powerful FEC method effectively corrects errors caused by noise. Additionally, a MAC-layer retry mechanism enhances data recovery when FEC alone is insufficient. Together, these features ensure robust communication, even in environments with severe electromagnetic interference (EMI), such as electric fast transients (EFT) and surges.

The following figure illustrates this mechanism. If only a small number of data bits are corrupted, FEC can correct the errors, and an ACK is sent. However, if many data bits are corrupted, FEC cannot correct them, prompting a NACK to request a retry.

 

– OFDM for Reflection Management

Orthogonal Frequency-Division Multiplexing (OFDM) effectively mitigates the impact of frequency-selective fading by dynamically allocating data to high CINR (Carrier-to-Interference-plus-Noise Ratio) carriers. This allocation is continuously updated as network conditions change, ensuring optimal performance and enabling flexible, free-topology network configurations.

The following figure provides an example.

When using 32PAM, each carrier can load 5 bits of data.

However, if reflections occur, not all carriers can maintain a good CINR, leading to potential errors when loading the maximum data bits.

To minimize errors, more bits are allocated to carriers with good CINR, while fewer bits are assigned to carriers with poor CINR.

 

– State-of-the-Art Analog Front-End

With a high dynamic range exceeding 100 dB, Nessum’s advanced analog front-end technology effectively mitigates severe signal attenuation caused by low impedance. This high dynamic range enables point-to-point communication over distances of more than 1 km. It also ensures stable communication over several hundred meters, even in the presence of cable and splitter losses.

The following figure illustrates this concept. When a 1 km cable is used between Nessum devices, the typical cable loss at a 10 MHz bandwidth is approximately 0.5–1.5 dB/m. If a cable with a loss of 0.1 dB/m is used, the total cable loss amounts to approximately 100 dB (0.1 dB/m × 1,000 m). In this scenario, a dynamic range exceeding 100 dB enables successful signal decoding.

 

Beyond Power Lines: A New Era of Connectivity

By applying these innovations to twisted-pair and other wire-based networks, Nessum extends its robust, interference-resistant communication technology beyond traditional power line systems. As industries seek greater flexibility and reliability, Nessum is paving the way for the next generation of high-performance networking solutions.

 

Get Started Today

Order your Evaluation Kit and experience the benefits of Nessum today!

 

About the Author
Kengo Tamukai is a senior engineer specializing in wired and wireless communication technologies. With over 20 years of experience in LSI design, system architecture, and technical marketing, his expertise spans SoC design, OFDM-based technologies, and hybrid communication systems, driving innovation in modern digital networks.

Seamless IP Migration for Video Doorbell Systems

Video doorbells are becoming an essential feature in modern residential and commercial buildings. As demand for IP-based video intercom systems grows, building owners are seeking ways to upgrade their legacy analog doorbell systems without incurring excessive costs or disrupting existing infrastructure.

However, retrofitting multi-dwelling buildings with IP-based video doorbells presents significant challenges. System integrators require a cost-effective communication technology that simplifies deployment while maintaining high performance and reliability.

The Challenge: Retrofitting Without Rewiring

One of the biggest obstacles to upgrading analog doorbell systems is the cost and complexity of installing new Ethernet cabling. In many cases, the cost of new wiring exceeds that of the doorbell hardware itself.

Beyond replacing the doorbell units, system integrators often need to re-cable the entire building, requiring extensive electrical work. This can lead to project delays, higher labor costs, and inconvenience for residents.

To address these challenges, system integrators need a solution that enables IP-based video doorbell functionality without requiring costly rewiring.

10BASE-T1L: A Potential Solution, but with Limitations

10BASE-T1L is a promising wired communication technology that supports long-distance connectivity up to 1 km, making it a strong candidate for large buildings and industrial environments where Ethernet wiring is impractical.

However, 10BASE-T1L has a major limitation—it only supports point-to-point communication. While point-to-point connections can be applied in a daisy-chain topology where multiple devices are cascaded, they do not support a bus topology.

The Problem with 10BASE-T1L

Since 10BASE-T1L relies on one-to-one connections in a daisy-chain topology, the biggest drawback of this approach is that if a single device in the middle of the chain fails, all downstream devices lose connectivity.

For example, in a building with ten video doorbells connected in a daisy chain, if the third device fails, the fourth and all subsequent devices will also go offline. This poses a serious reliability risk in multi-tenant buildings, where stable communication is essential.

To overcome this limitation, a loop topology (ring structure) can be used. A loop topology provides multiple communication paths, ensuring that if one device fails, the signal can still reach the remaining devices via an alternative route. However, implementing a loop topology requires additional cabling, which may not be feasible in all retrofit scenarios.

 

The Solution: Nessum (HD-PLC) – A Superior Alternative

This is where Nessum (HD-PLC) provides a game-changing solution.

Nessum employs Orthogonal Frequency Division Multiplexing (OFDM), which offers two key advantages:

• High Bandwidth Efficiency – Enables Mbps-level data transmission, supporting multiple HD video streams over existing 2-wire cabling.
• Strong Reflection Resistance – Ensures stable communication even in environments where signal reflection is a concern, making it ideal for free-topology networks.

These advantages enable installers to flexibly deploy video doorbell systems in a way that suits the existing infrastructure. Additionally, Nessum’s high bandwidth efficiency ensures that multiple HD video streams can be transmitted without interference.

Furthermore, Nessum’s Ethernet Bridge function provides L2 switch-equivalent capabilities, allowing for seamless network expansion by easily connecting multiple sub-networks. This means integrators can build scalable and flexible video doorbell systems without requiring extensive rewiring.

With these advanced features, Nessum is the optimal solution for upgrading analog doorbell systems to IP video while ensuring cost-effective, reliable, and scalable deployment.

Get Started Today

Order your Evaluation Kit and experience the benefits of Nessum today!

 

About the Author
Kengo Tamukai is a senior engineer specializing in wired and wireless communication technologies. With over 20 years of experience in LSI design, system architecture, and technical marketing, his expertise spans SoC design, OFDM-based technologies, and hybrid communication systems, driving innovation in modern digital networks.