Wireless networks are no longer confined to homes, offices, public hotspots, transportation terminals, and cafes. My city now offers free wireless access on public buses and in public spaces, making wireless networks increasingly ubiquitous. It is evident that the expansion of wireless networks will continue to accelerate and grow over time.

With the rapid proliferation of wireless networks, there is an ever-increasing demand to support more users. Previously, individuals might connect only their phones to the network. Today, it is common for people to connect multiple devices, such as phones, laptops, and tablets. Additionally, the surge in wirelessly connected IoT devices further amplifies the demand for wireless network connectivity.

Figure 1. Ubiquitous wireless networks.

While it is challenging to determine the exact number, it is estimated that over 90% of commercial Wireless Access Points (WAPs) are powered by Power over Ethernet (PoE). PoE is a unique technology introduced by PowerDsine and subsequently acquired by Microchip Technology in 1998. This technology enables power to be transmitted over an Ethernet cable that already carries data. Consequently, a WAP requires only one cable to provide both power and data.

The advancements in wireless networks are placing new demands on switches and other devices that supply power. To better understand these demands, we must first examine the current trends in the marketplace.

Trends in Wireless Access Points

A significant number of networks are currently utilizing Wi-Fi® 5 (802.11ac), which was introduced in 2013. This standard offered higher data transfer rates, increased capacity, and enhanced performance compared to its predecessor, Wi-Fi 4 (802.11n). Wi-Fi 5 supports a maximum data rate of 3.5 Gbps.

Wi-Fi 6 (802.11ax) was introduced in 2019, providing further improvements in speed, capacity, and performance. Unlike Wi-Fi 5, which operates primarily in the 5 GHz band, Wi-Fi 6 supports both the 2.4 GHz and 5 GHz bands.

In 2020, Wi-Fi 6E, also known as Wi-Fi 6 Extended, was introduced, extending operations to the 6 GHz band. This addition provided extra spectrum, reducing congestion and improving overall network performance. Both Wi-Fi 6 and Wi-Fi 6E support maximum data rates of up to 9.6 Gbps.

Figure 2. The evolution of Wi-Fi. 

Wi-Fi 7 (802.11be) was announced in January 2024. Designed to meet the growing demands for high-speed internet and an increasing number of connected devices, Wi-Fi 7 supports data rates of up to 30 Gbps. Each generation of Wi-Fi standards has progressively supported more users, higher speeds, and faster data rates.

There has also been significant progress in energy efficiency over this period. In 2014, shortly after the introduction of Wi-Fi 5, the U.S. Department of Energy (DoE) ratified their Level IV efficiency standards. Today, the DoE has advanced to Level VI and has defined, but not yet implemented, Level VII standards. Additionally, every major country has implemented its own energy efficiency programs.

Another aspect of energy efficiency is distribution. To streamline energy distribution, many Wireless Access Point (WAP) manufacturers are incorporating features such as PoE power-forwarding into their designs. This allows excess power from the receiving WAP to be forwarded to subsequent WAPs, making energy distribution more efficient.

In summary, the trends in WAP indicate advancements in power, efficiency, user capacity, data handling, and speed.

Powering Wireless Access Points

The proliferation of wireless networks will necessitate a significant increase in WAPs of all types. These WAPs will need to be connected to the network and powered efficiently. PoE has become the preferred method for powering these devices due to its simplicity and efficiency. PoE requires only one cable, which simplifies installation. Classified as Class 2 power by the National Electric Code (NEC), PoE is considered safe and does not require a certified electrician for installation, nor does it necessitate conduit or shielding. Ethernet standards allow for up to 100 meters of cable, providing flexibility in device placement without the need to be near a power source.

However, currently, only approximately 20% of networks provide PoE power. Therefore, when installing over an existing network, additional power will need to be integrated. In 1999, PowerDsine recognized that it would take several years to design and manufacture new Power Source Equipment (PSE) Integrated Circuits (ICs) to add power to Ethernet cables within switches, routers, and gateways. To address this, they introduced a device called the midspan, also known as an injector.

Figure 3. Midspan powering an outdoor WAP.

The midspan connects to an Ethernet cable from a switch that does not provide power. The output is a second Ethernet cable that carries both power and data. Incorporating a Midspan before the WAP is the fastest and most cost-effective way to add power to a network. For venues requiring multiple WAPs, multi-port midspans can be mounted on a rack above the existing switch to add power to the network.

Even when installing new switches, it is not guaranteed that they will provide power. Many switches sold today are PoE-enabled. Additionally, even PoE-enabled switches have a limited power budget, meaning they may not provide full power on every port. Therefore, for new non-PoE switches and PoE switches with insufficient power budgets, the PoE midspan remains a crucial component for powering wireless networks.

Selecting The Right Device

Before selecting a device, it is crucial to determine whether the WAP will be connected to an existing wired network or if a new network will be created. If connecting to an existing network, check if it PoE enabled. If not, midspans are the most cost-effective solution to add power to the network.

If a new network is being created, consider whether it will be built using PoE switches. Some prefer to isolate the switch from the power source, as switches are often replaced more frequently due to technological upgrades compared to PoE midspans. This preference may lead to the selection of a non-PoE switch and the introduction of power using a midspan.

When midspans are required, several factors must be considered to select the appropriate device:

• Power
• Ports
• Environment
• Data Rate

Most WAP manufacturers adhere to IEEE PoE standards when designing their midspans. The IEEE has defined three standards with preset power levels known as classes:

• IEEE 802.3af: 3 Classes - 4W, 7W, and 15.4W
• IEEE 802.3at: 4 Classes - all previous plus 30W
• IEEE 802.3bt: 8 Classes - all previous plus 45W, 60W, 75W, and 90W

The WAP manufacturer will specify the required power, and the IEEE standard followed.

The number of ports needed depends on the number of devices being supported. Many WAP manufacturers offer a single port midspan as a powering option for their devices. The manufacturer may offer a bundle of one single port midspan with each WAP.

System integrators installing multiple WAPs at a site often prefer a multiport midspan solution. This simplifies installation by mounting the midspan above the switch on the rack. Multiport midspans can also offer additional features such as scheduling.

It is also important to consider the installation environment for the WAP and midspans. For outdoor WAP deployments, select a device designed to operate in such conditions. Placing an indoor or industrial units in a National Electrical Manufacturers Association (NEMA) enclosure often results in high failure rates. Outdoor midspans and switches must be designed for outdoor environments, ideally with an Ingress Protection rating of at least 66, though 67 is preferable to ensure protection against the elements. They should also have a temperature range suitable for extreme weather conditions and surge protection to handle electrical storms.

Additionally, the midspan must support current data rates of up to 10 Gbps. While most midspans today support data rates up to 1 Gbps, there are options available that offer 2.5 Gbps, 5 Gbps, and even up to 10 Gbps. These higher data rates are required for Wi-Fi 6 and beyond.

Finally, an increasing number of manufacturers and consumers are prioritizing sustainability. Consumers are demanding greater focus on environmental impact and energy efficiency. To ensure compliance with current and evolving global standards, it is essential that midspans adhere to these requirements.

The Road Ahead

The benefits of emerging Wi-Fi standards will continue to include increased user capacity, enhanced data handling, and higher speeds. The recently ratified Wi-Fi 7 standard supports data rates of up to 30 Gbps. As new devices are designed to incorporate this standard, we can anticipate that midspans powering these devices will also support these data rates. Although the specifications for Wi-Fi 8 are not yet finalized, discussions suggest it may support data rates of up to 46 Gbps.

Figure 4. PoE a green sustainable energy efficient power source.

Energy efficiency standards are also expected to advance. The focus remains on DoE Level VI, which has been in effect since 2016, and the newly defined Level VII, which emphasizes no-load conditions. This specifies the amount of energy that can be consumed when the unit is not delivering power. This is particularly important for PoE midspans, as they do not deliver power when a WAP does not require it, remaining in a wait or "No Load" state, ready to provide power when needed. It is crucial to ensure that all powering devices are designed to meet or exceed current and emerging standards, not only for DoE but also globally.