Before You Try Power Line Communication (PLC): 5 Key Challenges That Could Kill Your Connection

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Power Line Communication (PLC) sounds like a dream: transforming your existing electrical wiring into a data network, saving you the cost and mess of new cables. It’s a brilliant concept with huge potential.

But in real-world situations, PLC doesn’t always work smoothly. There are several issues that can block or weaken the signal. If you don’t pay attention to these, your connection might be slow, unstable, or fail completely.

Here are five important challenges to watch out for when using PLC.

 

1. Signal Fade-Out Over Long Cable Runs

Even though power cables carry electricity well, they’re not perfect for carrying high-speed data signals. Over long distances—especially at the high frequencies used by PLC—the signal gradually fades. It’s like a voice getting quieter the farther it travels.

This signal fading depends on the cable material, the length of the cable and the frequency being used. As a rough guide:

  • Over 100 meters, the signal may drop to about one-tenth (1/10) of its original strength.
  • Over 400 meters, the signal may drop to about one-thousandth (1/1,000).

This kind of loss usually isn’t noticeable in homes, but it becomes important in large buildings like factories or offices with long wiring.

 

What you can do:

  • Home use: Most homes don’t have cable runs longer than 100 meters, so the signal stays strong enough for PLC to work well.
  • Industrial use: In large facilities with long wiring, using lower-frequency PLC is recommended. Some PLC systems like Nessum support long-distance communication by adjusting the frequency.

2. Too Many Paths for the Signal (Branch Splitting)

Your power wiring usually splits into many branches—especially at the breaker box. This is where the signal can get lost or bounced around.

At low frequencies (like normal electricity), this isn’t a big deal. But at the high frequencies used by PLC, each branch splits the signal more and more—like shining a flashlight through lots of mirrors. The more branches there are, the more the signal gets scattered and weakened.

In the worst case, each branch can reduce the signal by half, and if there are multiple branches in a row, the loss becomes exponential: With 20 branches, depending on the spacing between them, the loss can range from 1/20 to 1/1,000,000.

Note: This simplified estimate does not account for additional signal reflections from impedance mismatches.

What you can do:

  • Home use: Most homes have up to 10 branches, and because the branches are spaced closely together, the signal loss is usually minimal and not a problem for modern PLC devices.
  • Industrial use: In buildings with many and widely spaced branches, it’s a good idea to install signal repeaters (devices that boost the signal) in each breaker box.

3. Devices That Absorb Your Signal (Low Impedance Loads)

Most appliances and electronic devices (like TVs, washing machines, or PCs) are designed to reduce noise, which is good for safety—but not so good for PLC. These devices often include special parts (called X-capacitors) that “absorb” high-frequency signals like those used by PLC. As a result, communication signals are weakened to about 1/100 to 1/1,000.

 

Also, because these signals travel at high frequencies, even a short distance (like 30–50 cm) between the device and the outlet can change how much the signal is affected.

What you can do:

  • Home use: Try using a short power extension cord (1 meter or so) between the outlet and your noisy device. It often improves the signal.
  • Industrial use: Avoid plugging unknown or unfiltered machines into the same power line as your PLC device. You can also install special parts (like coils) to help keep the signal strong.

4. Noise from Electrical Equipment

Some devices, especially those with motors (like hair dryers or factory machines), create a lot of electrical “noise” that spreads into the power lines. This noise can interfere with the PLC signal, like trying to talk in a room full of shouting people.

Even advanced PLC systems can struggle with noise.

For example, Nessum is capable of maintaining communication even when the signal strength is reduced to less than one ten-billionth (1/10,000,000,000) of its original level. However, when strong noise is present, this high sensitivity can’t be fully utilized, and communication may still fail.

What you can do:

  • Home use: Use noise filters (small plug-in devices) to reduce interference.
  • Industrial use: Install EMC filters to separate noisy machines from your communication lines.

5. Transformers – The Signal Can’t Cross Them

Large buildings often use transformers to change high-voltage electricity into a lower voltage for regular use. Unfortunately, PLC signals can’t pass through transformers easily. It’s like trying to speak through a thick wall—most of the sound gets blocked.

 

What you can do:

  • Home use: This usually isn’t a problem—homes rarely have transformers inside.
  • Industrial use: Use wireless bridges (like Wi-Fi or specific PLC wireless products such as Nessum-Air) to send signals across different parts of the building.

Conclusion

PLC is a great way to turn your power outlets into network ports without installing new cables. But it’s not plug-and-play in every situation. Real-world environments—especially in industrial or complex buildings—introduce challenges like signal loss, noise, and electrical interference.

The good news:
If you understand and plan for these 5 key challenges, you can enjoy fast and stable PLC communication both at home and in large facilities.

 

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.

The Future of Building Networks: Broadband PLC as the Communication Backbone

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As decarbonization efforts accelerate, Zero Emission Buildings (ZEBs) have become a key target in climate policy. Achieving ZEB status requires automation systems that can efficiently monitor and control major energy loads like HVAC and lighting.

While large buildings can absorb the cost of complex infrastructure, small-to-medium-sized buildings often struggle with the high expense of separate power and communication networks. A more integrated, cost-effective solution is needed.

Broadband Power Line Communication (PLC) offers a promising alternative. By using existing power lines for both data and energy transmission, PLC reduces wiring complexity and cost. When paired with wireless technologies, it supports a hybrid architecture that enables flexible, scalable control across a building.

With these capabilities, broadband PLC is emerging as a next-generation communication backbone for building automation.

 

Current Building Automation Architecture

Most building automation systems today rely on RS-485 communication. Although mature and widely used, RS-485 presents several limitations:

  • It requires separate wiring for communication and power, increasing material and labor costs.
  • Often, the communication and power networks have mismatched topologies, complicating installation and maintenance.
  • Its daisy-chain topology is fragile—failure of a single device can impact the entire network.
  • It is susceptible to common installation errors, such as flipped polarity, grounding issues, and missing end-of-line (EOL) resistors.

To meet safety regulations, RS-485 systems typically use low-voltage power lines (e.g., AC24V, DC24V, DC30V), which do not require licensed electricians for installation.

Alternatives to RS-485

Several alternatives to RS-485 are currently being explored:

– Wireless

Wireless systems eliminate the need for communication wiring and enable flexible device placement. However, they pose challenges in terms of reliability and interference:

  • Signal quality is highly sensitive to changes in the physical layout—partition walls, for example, can cause over 10 dB of attenuation.
  • Extending coverage often requires reducing bandwidth or increasing transmission power, both of which can cause interference with nearby systems.
  • Reliable operation demands advanced RF planning and detailed site surveys.

 

– 10Base-T1L with PoDL

10Base-T1L enables simultaneous transmission of data and power over a single twisted pair using Power over Data Line (PoDL) technology, supporting up to 60W of power. While this simplifies wiring, it has notable constraints:

  • It supports only point-to-point communication, requiring either:
    • A star topology with L2 switches, or
    • A daisy-chain topology with dual-port devices.
  • When PoDL is used, the number of daisy-chained nodes is limited by power distribution constraints.

Despite its high bandwidth and low latency, its rigid topological requirements can limit flexibility in real-world building layouts.

Broadband Power Line Communication (PLC)

Broadband PLC leverages existing power lines for data transmission, making it a compelling solution for building automation—especially over dedicated power lines like AC24V or DC24V. Its key advantages include:

  • Reduced wiring cost by eliminating separate communication lines.
  • Predictable network behavior—since only automation devices are connected, interference is limited and controllable.
  • Support for bus and free topology, aligning naturally with the structure of power line networks.

In addition to these benefits, broadband PLC also addresses several known limitations of RS-485.

RS-485 Limitation  Broadband PLC Advantage
Daisy-chain topology only Supports Free topology (bus, star, daisy, loop)
Flipped polarity Polarity-agnostic modulation schemes
Grounding problems Isolation via compact, low-cost transformers
EOL resistance requirement No EOL resistor required

 

 

– Technical Considerations

Even with dedicated lines, PLC must address certain technical issues:

  • X-capacitors in power supplies lower line impedance, attenuating communication signals.
  • Noise from switching devices can degrade signal quality.

To mitigate these issues:

  • Inductive impedance elements (e.g., coils) can be added to stabilize line impedance and suppress noise.
  • Multi-hop PLC protocols, such as Nessum, help maintain stable communication even over high attenuation or in noisy environments.

These features enable deterministic network behavior, simplifying system design. Nessum’s multi-hop capability supports up to 1,024 nodes, allowing the network to scale effectively—making it highly suitable for building automation applications.

 

 Extended Applications

By adopting the same architecture, even higher-voltage AC lines (e.g., AC110V or AC230V) can serve as reliable communication channels. This enables the use of PLC for power-hungry applications while maintaining the same benefits, making this approach a viable communication backbone for building automation—even in high-demand environments such as HVAC systems.
In this scenario, adding EMC filters at the origin of the power line further enhances signal stability.

 

Furthermore, by combining broadband PLC with wireless technology, a hybrid architecture can be realized: PLC serves as the backbone network, while wireless provides flexible access to end devices such as lighting fixtures and sensors. This approach enables centralized control over the two major sources of energy consumption in buildings—HVAC and lighting—through a cost-effective and scalable infrastructure.

 

 

Conclusion

Broadband Power Line Communication presents a practical, scalable, and cost-effective alternative to traditional wiring in building automation. By leveraging existing power lines and modern PLC technologies, it enables:

  • Simplified installation
  • Reduced material and labor costs
  • Resolution of legacy system issues such as RS-485
  • Deployment of robust, flexible networks—even in retrofit scenarios

Moreover, when combined with wireless technologies in a hybrid architecture, broadband PLC can act as a reliable communication backbone, enabling centralized control of both HVAC and lighting—the two primary sources of energy consumption in buildings. This integrated approach supports the development of smart, energy-efficient infrastructures and offers a viable path toward Zero Emission Buildings (ZEB), especially for small-to-medium-sized facilities seeking both sustainability and affordability.

 

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.

Expanding Robust Communication to Twisted-Pair & Any Wire Networks

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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.

How to Maximize System Performance with Advanced Wired Communication Technology

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Planning for Future Bandwidth Growth in Wired Communication Systems

When selecting the ideal wired communication technology for your system, the right solution goes far beyond just covering the necessary range. How much bandwidth flexibility do you need to future-proof your system? Future bandwidth demands are constantly evolving as applications become more data-intensive. Will your system be able to handle increased data loads in the coming years?

To address these concerns, Nessum’s 4th Generation Technology introduces a game-changing solution: Flexible Channel OFDM. This cutting-edge technology offers a broad selection of channels, enabling you to choose from options that provide up to 8 times the range and 64 times faster PHY (Physical Layer) rates. With this unprecedented flexibility, you can fine-tune your network’s performance, ensuring it’s always optimized for your unique needs.

Understanding the Cable Loss and Frequency Range

In any wired communication system, cable loss plays a crucial role in signal performance. In the MHz frequency range, the skin effect becomes dominant, causing signal attenuation that increases with frequency. Essentially, as the frequency rises, the signal strength decreases, typically in proportion to the square root of the frequency.

For example, reducing the frequency band by a factor of 100 can increase the communication range by up to 10 times. This understanding of cable loss is crucial when selecting the ideal frequency band for your network, allowing you to balance performance and range based on your needs.

The Challenge with Traditional Wired Communication Technologies

Traditional OFDM-based technologies—such as narrowband PLC (Power Line Communication) (e.g., G3-PLC) and broadband PLC (e.g., Homeplug AV2)—often present difficult trade-offs. These systems can have frequency differences of up to 100 times and PHY rate variations of up to 1000 times, forcing users to make a tough decision between range and speed. For example, if a broadband PLC system cannot provide sufficient range, the only option is to switch to a much slower narrowband PLC, which significantly reduces data transmission rates. This forces a trade-off between coverage and performance, making it difficult to optimize the system.

How Flexible Channel OFDM Works

Nessum’s Flexible Channel OFDM solves this issue by offering a wide range of frequency options, giving you the flexibility to choose between low-frequency bands for extended range or high-frequency bands for faster speeds. This versatility ensures you can find the perfect balance between range and performance for your system. Here’s how it works:

  • High-frequency band (CID x-8): This band uses frequencies from 4 MHz to 56 MHz, supporting high-speed communication with PHY rates (~500 Mbps), but with a shorter range.
  • Low-frequency band (CID x-24): Operating between 62.5 kHz and 875 kHz, this band offers a significantly longer range, though with a slower PHY rate (~7.8 Mbps).

 

For example, if CID x-8 provides a 1 km range, the following channels offer the corresponding distances:

  •     CID x-1: 1.4 km
  •     CID x-2: 2 km
  •     CID x-24: 8 km

In this case, if your system needs a 2 km range, selecting CID x-2 gives you the ideal combination of range and speed, without the need to compromise.

The Power of Flexibility

Nessum’s Flexible Channel OFDM technology offers a level of flexibility that traditional wired communication technologies simply can’t match. Whether you need to extend range for remote locations or push the limits of speed for high-demand applications, this technology gives you the freedom to choose the optimal channel for your system’s needs.

Conclusion

With Nessum’s 4th Generation Flexible Channel OFDM technology, you no longer need to choose between range and performance. The broad selection of channels allows you to design a wired communication system that is both highly efficient and adaptable to future demands. By selecting the right channel for your network, you can maximize system performance today and ensure it remains scalable for the future.

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.

 

Upgrade Analog Doorbell Systems to IP Video: Cost-Effective Retrofit with Nessum (HD-PLC)

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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.