HD-PLC Technical Overview — Key Features That Make HD-PLC One Of The Most Advanced Networking Solutions
The global power line communication (PLC) market is expected to grow from $8.1 billion in 2020 to $25.2 billion by 2027.
The rapid growth of the PLC market has to do with two key factors:
- The increasing demand for reliable, cost-effective networking solutions from businesses, private customers and public organizations
- The increasing number of grid network and Internet of Things applications that require such solutions
For example, the global market for building automation — one of the prime applications of power line communication — is projected to reach $273 billion by 2023.
The recognition of power line communication as a reliable, cost-effective solution can be largely credited to the arrival of High-Definition Power Line Communication or HD-PLC.
We already covered the basic principles of HD-PLC that make this technology a prime choice for commercial and public applications. If you’re still on the fence, be sure to check out our recent post.
However, we’d like to present a more detailed examination of HD-PLC’s technical features that differentiate it from other network solutions and older powerline communication designs.
And that is exactly what this blog post will do.
In addition to drawing a comparison between HD-PLC and other networking solutions, we will also cover the key differences of HD-PLC variants and communication standards.
By the end of this post, you will be well-informed about the technology behind HD-PLC that makes it such an advanced networking solution.
What Are The Main Technical Characteristics Of HD-PLC?
HD-PLC shares its basic operating principle with other types of power line communication networks — using electricity power lines and other existing wiring installations to transfer digital data, such as an Internet connection.
PLC networks are able to achieve this thanks to the different frequencies that digital data signals and electrical power have.
Alternating current (AC) that powers most devices and appliances we use on a daily basis travels slowly at a rather low frequency of 50 or 60 Hz.
By comparison, the data in the most basic Narrowband PLC network travels at frequencies between 3 and 500 kHz, while the broadband HD-PLC uses between 2 and 28MHz.
As a result, both streams can be transferred via a single cable without any interference because the frequencies of electric current and digital data are so different, the PLC network can analyze the two streams and separate them.
However, HD-PLC takes the basic power line communication principles a step further by relying on the unique, efficient Wavelet-OFDM modulation method.
Wavelet-OFDM is a type of Orthogonal Frequency-Division Multiplexing — a data signal modulation technology that’s used in most contemporary telecommunication standards, such as Wi-Fi.
OFDM splits the data stream into separate sub-streams, which have low individual bit rates. This helps achieve smaller data loss, interference in noisy broadband networks.
Wavelet-OFDM, on the other hand, uses the wavelet transform method to modulate the signal, resulting in even lower levels of data loss and interference with other radio frequency transmissions.
In the case of HD-PLC, the Wavelet-OFDM allows it to achieve a theoretical maximum data transmission rate of 240 Mbps.
However, the exact data transmission rate depends on the version of the HD-PLC protocol.
As such, HD-PLC is capable of transmitting data very efficiently, without being affected by interference from other devices and equipment.
This means that HD-PLC supports a variety of networking functionalities, such as:
- VoIP communication
- AV streaming
- File transfer
- 128-bit AES encryption
IEEE 1901a Vs. IEEE 1901-2010 — Comparing The Two Broadband Network Standards
HD-PLC is based on the IEEE 1901-2010 communication standard.
As the name suggests, it was established in 2010 as an international standard for broadband over power line (BPL) communication that HD-PLC is an example of.
Upon its release, IEEE 1901 introduced several improvements to the PLC technology, including a maximum data transmission rate of over 240 Mbps.
In order to accommodate a wider range of PLC manufacturers, equipment and applications, IEEE 1901 was designed to accommodate two PLC communication solutions:
- Fast Fourier Transform (FFT) method of OFDM modulation, mostly found in older PLC networks and widespread in Europe and the United States
- Wavelet method of OFDM modulation, found in HD-PLC networks and most common in Japan
However, by the end of the decade, the 2010 version of the standard was no longer adequate to support the increasingly widespread IoT applications.
As such, an amendment to the standard known as IEEE 1901a or IEEE 1901a-2019 was introduced, as the name suggests, in 2019.
The 2019 amendment included a major feature that made it possible for the standard to accommodate the IoT use cases — flexible channel wavelet (FCW) of physical (PHY) and media access control (MAC) levels.
Commonly abbreviated as PHY/MAC FCW, this technology makes it possible to control the different channels or frequency bands of an HD-PLC network.
Depending on the exact data usage and bandwidth needs of the network’s components, this flexible feature allows further optimization of the network’s performance for various IoT applications with different needs.
The outcome of this approach are the two key advantages that IEEE 1901a-2019 has over IEEE 1901-2010:
- Higher data transmission rate: IEEE 1901a-2019 offers 15 selectable channels within a single physical layer, boosting the data transmission rate to a maximum of 1 Gbps.
- Wider range: The selectable channels of the IEEE 1901a-2019 can also be taken advantage of in another way, allowing a compression of the communication bands for long distance applications. As a result, the range of a network can be increased by 2.5 times — albeit, at the expense of the data transmission rate.
The cost-effectiveness and reliability of HD-PLC network solutions make them perfect for multiple IoT applications – such as building automation.
HD-PLC Complete Vs. HD-PLC Multi-Hop — How Are They Different?
Because of its flexibility, the HD-PLC technology can be divided into two standards that find applications in different spheres — HD-PLC Complete and HD-PLC Multi-hop.
The main difference between the two standards lies in their respective network topologies.
HD-PLC Complete is the basic type of HD-PLC, based on the IEEE 1901 standard. A typical HD-PLC Complete network is made up of individual nodes that communicate with each other one-on-one.
It provides higher communication speeds and is mostly used in application, such as video streaming, CCTV systems, HVAC systems and smart grids.
HD-PLC Multi-hop is a bit more complex and interesting. While it is also based on the same IEEE standard, it includes the hopping technology, outlined in the ITU-T G.9905 standard.
Also known as the Centralized Metric-Based Source Routing (CMSR) protocol, this technology allows for the data signal to “hop” between several terminals of a network, all of which are connected to one master node in a tree-like structure.
The maximum number of “hops” that the signal can perform in a single network is 10 — which means that the signal can travel through as many as 10 terminals, which, in turn, can supply as many as 1,024 individual nodes.
The key practical implication of this technology is that HD-PLC Multi-hop can be used in larger networks that can extend to distances of up to 10 kilometers.
The HD-PLC Multi-hop standard is usually found in applications, such as building automation and smart city infrastructure and other use cases that command larger networks.
HD-PLC Vs. Other PLC Network Solutions — How Is HD-PLC Superior?
Comparing HD-PLC with other power line communication standards effectively means comparing two types of PLC networks:
- High-frequency, broadband networks that HD-PLC is a part of
- Low- and medium-frequency, narrowband networks that mostly follow older power line communication standards
In this comparison, HD-PLC emerges as a superior solution across three key characteristics:
- Speed: As stated previously, HD-PLC networks can potentially achieve a maximum data transmission rate of 240 Mbps. Of course, this number is purely theoretical, and the maximum effective HD-PLC data transmission rate depends on the number of channels within a network and the distance. Nevertheless, it’s still much higher than the average maximum rate of 200 kbps in low-speed, narrow-band PLC networks that work at kHz frequencies.
- Range: It is important to note that HD-PLC Complete has a lower range than narrow-band power line communication networks that can reach around 2 kilometers. However, using the aforementioned HD-PLC Multi-hop technology can help extend the network range to around 10 kilometers, which is vastly superior to both narrow-band PLC and other types of broadband PLC networking.
- Power consumption: HD-PLC equipment uses only around 2 watts.
HD-PLC — Technical Features Recap
HD-PLC is not only one of the most cost-effective and reliable networking solutions — it’s also one of the most technologically advanced ones.
The technology implements a series of innovations that help to achieve energy and data efficiency, such as:
- Wavelet-OFDM modulation that reduces interference and data loss
- Flexible channel wavelet (FCW) of physical (PHY) and media access control (MAC) levels that boost data transmission rate and network range
- Centralized Metric-Based Source Routing (CMSR) protocol, used in HD-PLC Multi-hop, that allows the building of networks that span large distances
- Lower power consumption and reduced operating costs compared to other PLC solutions
Combined with the relative simplicity of setting up and operating an HD-PLC network, these innovations make HD-PLC a prime solution for various IoT and grid network applications.