Introduction

Wireless networks typically include a few hardware components, some of which are mandatory while others provide additional "nice to have" functionality to the network. The most basic and most common hardware components are the Controller and the Access Point (AP). The Controller is the brain of the system and it manages any number of Access Points, which provide the actual wireless connectivity for individual user devices.

The hardware inside of a controller and AP is what dictates both the performance and price of a product—and the hardware can vary widely by manufacturer, even within a product line. While the AP’s firmware and the controller’s management software make some products standout, it is the underlying hardware that will dictate the overall capability of the system.

What you will learn:

  • 802.11 basics
  • Whether you need 802.11ac Wave 1 or Wave 2
  • AP hardware features

Controller

A controller is like the brains and control center of a wireless network. The controller can be a hardware appliance, software installed on a server, or a cloud-based service, and it is used to manage and control all of the APs in its network. The type and number of controllers you need depends on how you design your wireless network (see the Common Architectures section for more on wireless network design). Ultimately, the real benefit of the controller is in the ease of configuration and management.

Access Points

Access points consist of radios and antennas that provide the wireless signal out to the clients. APs are usually designed to be installed on a ceiling or wall. Each access point typically has two or more radios, four or more antenna, and one or more Ethernet port(s) to provide power to the AP and backhaul the traffic to the switching infrastructure. As schools adopt technology, the number of APs needed increases to support the growing number of devices.

Frequency Bands

Radio frequency available for use by different types of systems is broken up into frequency ranges called bands. The Federal Communications Commission (FCC) has established regulations about what types of devices can use the different bands. Wi-Fi devices operate in the 2.4 GHz and 5 GHz bands.

Key Decision: Do You Need Dual Band Access Points?
Overview

Most modern APs have at least two radios that transmit and receive client traffic. One of the radios operates in the 2.4 GHz band, and the other in the 5 GHz band. An AP needs to have a radio operating in each of these bands to be considered a "dual band" wireless AP.

Considerations

The 2.4 GHz band is significantly more crowded and prone to interference than the 5 GHz band. Whenever possible, clients (laptops, tablets, etc.) should be pushed to use the 5 GHz band for better overall system performance. Though single band (2.4 GHz only) APs are still available on the market and are less expensive than dual band, the cost savings is never worth the performance tradeoff.

However, signals of different frequencies also have different propagation characteristics. Signals with lower frequencies (2.4 GHz) are able to travel further distances and propagate through objects like walls and doors better than higher frequencies (5 GHz). Depending on the material type, whether it is drywall, cement, rebar, wood, or another material, 2.4 GHz signal may propagate through the wall but the 5 GHz signal will not. The denser the material, the less signal will leak through no matter the frequency.

Recommendations

EducationSuperHighway strongly encourages you to buy dual band APs rather than single band for optimal performance and to accommodate a large number and variety of clients.

Keep in mind that because of the higher frequency, the 5 GHz signal does not propagate through barriers (walls, doors, etc.) as well as the 2.4 GHz signal. If your wireless network today was designed for coverage by 2.4 GHz radios, you will need to purchase more dual band APs than are currently in your network for proper coverage by the 5 GHz radios as well.

802.11

802.11 is a wireless networking protocol commonly known as Wi-Fi. 802.11 has been around since 1997 and has evolved through several iterations, with each iteration improving on the capacity and resiliency of its predecessor.

802.11 VersionEncodingBandsTheoretical Data Rate
802.11bDSSS2.4 GHz11 Mbps
802.11gOFDM2.4 GHz54 Mbps
802.11aOFDM5 GHz54 Mbps
802.11nOFDM2.4 GHz, 5 GHz450 Mbps*
802.11ac Wave 1OFDM5 GHz1.3 Gbps**
802.11ac Wave 2OFDM5 GHz3.5 Gbps***
* 3 spatial streams (150 Mbps per spatial stream)
** 3 spatial streams (433 Mbps per spatial stream)
*** 4 spatial streams (867 Mbps per spatial stream)

802.11n

802.11n is an improvement on the 802.11a and 802.11g standards and increases the wireless speed from 54 Mbps to 450 Mbps.

The increased speed is accomplished by:

1.

MIMO - Multiple Inputs Multiple Outputs which splits a data stream over multiple transmitters and receivers (antennas). These multiple streams, called Spatial Streams, carry both unique and redundant data, making MIMO transmissions both faster and less prone to errors.

2.

Bonded channels - Previous 802.11 standards utilized 20 MHz wide channels (imagine a two-lane highway). 802.11n has the ability to bond two channels together, creating a 40 MHz wide channel (four-lane highway), which essentially can carry twice the amount of data, thus doubling the throughput of the radio.

3.

Frame aggregation - Legacy wireless standards require an acknowledgement for every frame sent. Frame aggregation is a feature that increases throughput by sending two or more data frames in a single transmission before an acknowledgement (ACK) is sent, which significantly reduces the overhead of the transmission.

802.11ac

802.11ac is the most recent standard in the 802.11 family, providing the highest throughput to date on the 5 GHz band.

This standard is being introduced in 3 waves. Products currently on the market are "Wave 1" and "Wave 2". Wave 1 increased theoretical speeds to 1.3 Gbps and Wave 2 increased to 3.5 Gbps.

Wave 1 achieves higher throughput by:

  1. Bonded channels, allowing wider channel widths, up to 80 MHz (eight-lane highway)
  2. More MIMO spatial streams
  3. Downlink multi-user MIMO (Mu-MIMO) allows an AP to service multiple clients simultaneously on the same channel
  4. High-density modulation (up to 256-QAM) allows more data to be sent per transmission, but requires very strong signal strengths and thus very clean Radio Frequency (RF) environment

Wave 2 achieves higher throughput than Wave 1 by:

  1. Increased MIMO spatial streams to 4
  2. Improved multi-user MIMO (Mu-MIMO) downlink client servicing simultaneously on same channel to 3
  3. Increased bonded channels allowing up to 160 MHz

Considerations:

  • Keep in mind, the theoretical throughput for an 802.11ac Wave 1 radio is 1.3 Gbps, though actual throughput is roughly 800 Mbps. The theoretical throughput for Wave 2 is 3.5 Gbps, but expect the actual throughput to be less. Theoretical throughput is the data rate that the radio is capable of, while the actual throughput of a radio is the real amount of data that the radio can transmit/receive per second. Actual throughput is the number that you should use to make design decisions. Don’t confuse data rate with throughput; though they are related, they are not the same.
  • Most Wave 1 and Wave 2 APs require PoE+ power (25.5w) to run at full performance, though most will run at reduced performance on standard PoE (15.4w).
  • Though very rare, some manufacturers are making their Wave 1 APs modular (upgradeable) to Wave 2.
Key Decision: Do You Need 802.11ac Wave 1 or Wave 2?
Overview
802.11n APs
  • 450 Mbps (5 GHz) + 217 Mbps (2.4 GHz) theoretical throughput
  • Approximately 400 Mbps real throughput
  • Powered by PoE
  • Operates in 2.4 GHz and 5 GHz bands
  • Wider variety of supported clients on the market today

802.11ac Wave 1 APs
  • 1.3 Gbps (5 GHz) + 217 Mbps (2.4 GHz) theoretical throughput
  • Approximately 900 Mbps real throughput
  • Most APs require PoE+
  • 802.11ac operates only in 5 GHz band but Wave 1 APs will also include a 802.11n 2.4 GHz radio
  • Allows for wider channels (80 MHz)
  • 802.11ac Wave 1 clients are now becoming affordable for schools to purchase
  • Supports higher density of clients than 802.11n

803.11ac Wave 2 APs
  • 3.5 Gbps (5 GHz) theoretical throughput
  • Most APs require PoE+
  • 802.11ac operates only in 5 GHz band and many Wave 2 APs may not include a 2.4 GHz radio
  • Allows for wider channels (160 MHz)
  • 802.11ac Wave 2 clients are not yet common or inexpensive
  • Have the options of utilizing a 4th spatial stream
  • Supports higher density of clients than 802.11ac Wave 1 by using Mu-MIMO
Considerations

With the recent release of 802.11ac Wave 1 and Wave 2 APs, the market is at an inflection point. Customers must decide whether to invest in the new technology now or for future generations of APs to be released. This is a difficult decision and each district will differ depending on the existing network and its intended future use. The district must consider the existing density, bandwidth needs, and hardware of the clients now and over the next three to five years to determine whether the additional throughput from an 802.11ac Wave 2 AP is necessary.

Client device type plays a role in the type of network you need. If all of your devices only support 802.11n and you do not plan on introducing 802.11ac clients within the lifetime of the new APs (3-5 years), an 802.11ac network should not be a priority. If you do plan on introducing 802.11ac clients within the next three to five years, they will be able to take advantage of the enhanced performance features of 802.11ac. For clients to take advantage of the new features in both Wave 1 and Wave 2, their hardware must be compatible. Many vendors continue to flood the market with 802.11n capable devices, rather than 802.11ac capable ones which has kept consumer costs down. Newer devices that support 802.11ac Wave 1 have recently become affordable for school districts to purchase. Wave 2 capable devices are not yet common and can be expensive. Timing of device refreshes and network upgrades alignments should be considered when choosing between Wave 1 and Wave 2. You do not want to rush to adopt Wave 2 and incur extra expense if your client devices will likely not have the ability to take advantage of the new features for a few years.

The cost of most technology drops with the introduction of new iterations or improved versions. In most cases Wave 1 APs are less expensive than newly introduced Wave 2 APs. It could take a few years of adoption before the price of Wave 2 drops significantly. With this in mind and also factoring in your client refresh plans for the next few years, investing in Wave 1 technology may be a better choice based on costs and client refresh cycles. With this in mind, it may be smart to consider 802.11ac Wave 2, not for this upgrade cycle, but for the next.

Recommendations

Advancing your network from 802.11n to 802.11ac is highly advisable. 802.11ac Wave 1 AP prices have become extremely competitive in comparison to both 802.11n and 802.11ac Wave 2 APs. If your district’s educational technology goals are geared toward a 1:1 or media rich environment within the next four years and you will have 802.11ac devices on the network, EducationSuperHighway recommends upgrading to 802.11ac Wave 1. Otherwise, if you have all 802.11n clients and an existing 802.11n network, you do not have aggressive technology goals over the next 3-5 years and you are on a tight budget, 802.11n (three spatial streams) will likely suit your needs and you may wait to upgrade. Also consider the advertised speed of each standard and what port speeds your wired switches ultimately support as there can be a cost impact for both the AP and switching gear needed. Bottom line, buy what you can afford.

Mix and Match Hardware

Since APs and controllers are such a large investment, experienced tech directors will always consider which pieces of their wireless network need to be upgraded, and which pieces can be used for a few more years. This might mean that you end up with a mix and match network, with various models of APs. If you are going to mix and match, there are a few things to keep in mind.

Most controllers are forward and backward compatible within the manufacturer’s product line, meaning that with a software upgrade, an older controller should be able to control newer 802.11ac APs. Similarly, a new controller typically is able to control older 802.11n APs. As a result, you can have both 802.11n and 802.11ac APs in the network. In fact, if you want to sneak a few more years out of 802.11n, you can always buy a few 803.11ac APs and install them only in your high density client areas (like testing rooms) to see better performance. It is important to keep in mind, however, that the coverage area for 802.11ac is slightly smaller than 802.11n so you cannot always swap APs out one-for-one.

Mixing and matching outside of a manufacturer’s product line is possible but not recommended. If you have a certain model of APs in your network now, and you want to move to another manufacturer, it is best to migrate whole chunks of the network (like an entire school) at a time rather than trying to manage multiple solutions in the same environment. It will be more time consuming for you to manage multiple solutions, and the two systems will tend to "fight" each other.

AP Interfaces

APs can have a few different types of interfaces that serve different purposes.

  • Management Port - Some product lines have APs with an out-of-band management port to troubleshoot and resolve any issues if an AP becomes "hung".
  • USB Interface - Some product lines have APs with a USB port for many different purposes like additional "on AP" storage, 3G/4G backhaul, Bluetooth beacons, or Mi-Fi tethering for cellular backhaul.
  • Ethernet Port(s) - All APs have one or more Ethernet ports, which they use to backhaul user traffic and, for the most part, to power the AP.
Key Decision: Do You Need a Second Ethernet Port?
Overview

Until recently most APs had a single Gigabit Ethernet (GbE) port to backhaul data. With the release of 802.11ac, many manufacturers are installing a second GbE port in their APs because of the advertised 1.3 Gbps speeds.

Considerations

Many manufacturers are adding APs to their product line with a second GbE port and charging a premium for those "higher performing" models. Don’t be fooled by this.

The theoretical throughput of a typical 802.11ac AP is 1.3 Gbps on the 5 GHz radio + 217 Mbps on the 2.4 GHz radio, so the common misconception is that a second GbE port is required. However, this logic is based on theoretical data rates of the two radios. The real throughput (which is typically ~60% of theoretical) of the 802.11ac Wave 1 AP will not exceed 1 Gbps.

Recommendations

Do not choose a more expensive AP if the only added functionality is a second GbE port. These are the only situations where a second Ethernet port is needed:

  • APs with more than one 802.11ac enabled radio (i.e., Xirrus arrays that have multiple 5 GHz radios)
  • APs that are modularly upgradeable to Wave 2 are not common. The real throughput of a Wave 2 radio will exceed 1 Gbps. Some Wave 2 APs come with multiple gigabit-capable Ethernet ports while others are coming equipped with NBASE-T/MGBASE-T-capable ports to address the need for multigigabit speeds. Ask your vendor about the options and product roadmaps.

Power Considerations

APs are typically powered by Power over Ethernet (PoE) provided by the switching infrastructure. As APs have become more complex, they have started to require more power. Power requirements for the newer 802.11ac Wave 1 and Wave 2 APs is different than 802.11n APs, consider the capabilities of your switching infrastructure before deciding on a solution.

Key Decision: Do You Need New Switches to Support PoE+?
Overview

Until the release of 802.11ac, APs operated at full performance on 802.3af power (15.4w), commonly known as PoE. Many 802.11ac APs require more than 15w to operate at full performance and require 802.3at (25.5w), commonly known as PoE+.

Considerations

If most 802.11ac APs are installed in a network with PoE switches, the new APs will not receive enough power to run at full performance. The APs will function, but they will start running in low power mode so you will not see expected performance from them.

Recommendations

Ideally, if you are purchasing 802.11ac APs that require PoE+, you should consider upgrading your switching infrastructure to PoE+ at the same time.

If you are upgrading your wireless network to 802.11ac but plan on leaving your PoE switching infrastructure in place, you should talk with the manufacturer to see what performance implications it will have. There are some 802.11ac APs that run full performance on PoE, but making that a requirement will limit the APs that are eligible. Instead, you may want to purchase a few PoE+ switches and plug the 802.11ac APs located in high density areas (like the library or assessment rooms) into the higher power switches.

External Antenna Option

All APs have one or more radios, plus one or more antenna per radio to amplify the signal that the radio is transmitting. There are a variety of antennas including omni, patch, or dish, which are used to focus the signal into wider or smaller areas. Indoor APs usually have antennas built into their enclosure that make the APs easier to install, more aesthetically pleasing, and less noticeable as a wireless access point. There are some APs with interfaces to connect external antennas, which can be useful if the AP will be placed in an area with an especially challenging Radio Frequency (RF) environment.

Outdoor/Hardened AP

An outdoor AP is an AP with a hardened enclosure that can withstand outdoor conditions, including extreme temperatures and moisture. These APs need to have not only a hardened enclosure, but also special seals around all cable and antenna joints to prevent water from entering the enclosure.

It is common for outdoor APs to have slightly different features and functionality than indoor APs. For example, mesh networking capabilities are much more common in outdoor spaces because it allows for the connecting of multiple APs when Ethernet cabling is not a possibility due to cost or the outdoor environment. Similarly, there are some channels that allow higher transmit power if the AP is located outdoors, so outdoor APs tend to have higher maximum transmit power levels than indoor APs.

Plenum Rated

The plenum space of a building is the "air-handling" space above the suspended ceiling where cabling is run and wireless APs are often installed. An AP model is considered plenum rated if it meets rigorous fire safety test standards to reduce fire hazards.

Your wireless network relies on your hardwired network to function. Structured cabling and switching gear are critical components of your wired infrastructure. Ethernet is a link layer protocol and is one of the most widely installed local area network technologies. Ethernet is specified in a family of standards known as IEEE 802.3. Ethernet networks can use both fiber optic cabling and a special kind of twisted-pair copper cabling to transmit data. Speed and distance of data transmissions have limitations, but continued advancements in technology are stretching those limits. It is important to have a basic understanding of the wired infrastructure to ensure you are making informed choices when planning your wireless architecture.

Structured Cabling

Twisted-pair copper is designated by grades called categories. Engineering improvements that address impedance and attenuation of the electric signal transmission have evolved into a number of category designations. Each category has different limits that impact data transmissions. The table below illustrates Categories 5e, 6, and 6a and important aspects of each type.

Cable Grade (copper)Distance (m) @ Data Rate
1 Gbps2.5 Gbps5.0 Gbps10 Gbps
Cat 5e 100100100*n/a
Cat 6 10010010055
Cat 6a100100100 100
*only works in special cases

Fiber Optics. Unlike copper cabling that transmits electrical signals over the media, fiber optics uses light for transmission. Light has much different physical qualities than electricity, so the transmission is not prone to electromagnetic interference or other common issues with copper cabling. Two major types of fiber optics are multi-mode (MM) or single-mode (SM). The electronics used to send light down the fiber optic cable must also be designated for MM or SM transmission because the signal strengths of the optics are different.

You will see MM implementations inside of buildings. A good practice is to use MM fiber optics to connect your MDF (main data frame) to your IDFs (intermediate data frame) to maximize transmissions speeds on network segments. When connecting data closets which are further than 100m apart, using copper cabling will not be possible. SM signals travel further distances and are commonly found between buildings such as your WAN (wide area network) links. The price difference for the required SM optics has become negligible in comparison to MM optics. SM can also be used within buildings for LAN (Local Area Network) and these implementations are becoming more common because of the expanded distances and throughput supported by SM. Using SM within buildings future proofs your LANs to meet anticipated demand from increased data transmission capacity between data closets.

Gigabit Ethernet Distances for Fiber Optic Media
Cable TypeDescription1 GbE Distance1 GbE Distance10 GbE Distance10 GbE Distance
MultimodeMeters @ 850 nmMeters @ 1300 nmMeters @ 850 nmMeters @ 1300 nm
OM1Standard30055033N/A
OM2Standard750600150N/A
OM3Laser-optimized1000600300N/A
OM4Laser-optimized1000600550N/A
1 GbE Distance1 GbE Distance10 GbE Distance10 GbE Distance
Single-modeMeters @ 850 nmMeters @ 1300 nmMeters @ 850 nmMeters @ 1300 nm
OS2Standard SMF5000N/A1000040000

Switches

Type and Function. Network switches link the network together. Unlike hubs, which forward all packets to all ports all the time, a Layer 2 switch forwards traffic only to ports based on destination MAC address. Virtual LANS or VLAN support is also important as they break up broadcast domains. A Layer 3 switch can perform routing functions in addition to switching. When a client sends traffic to another subnet, the destination MAC address in the packet will be that of the default gateway, which will then accept the packet at Layer 2 and proceed to route the traffic to the appropriate destination based on its routing table. Some vendors have created switches that can also function as distributed wireless controllers, however, with increased functionality comes with increased costs.

Form Factors. Switches come in 1u and 2u rack mountable forms. Many vendors allow stacking or cascading switches together to function as one large switch. There is a limit to the number of switches that can be cascaded together. Another form is the chassis-based blade that offers expansion via blades to accommodate port growth in a data closet. Chassis come in various sizes allowing for expansion and growth using modular blades that slide into the chassis and share a backplane for processing data traffic.

Port Speeds. Network switch copper ports typically support 10/100/1000Mbps data transmissions speeds. Most vendors allow for ports to autonegotiate both port speed and duplex with the devices connected on the alternate end of the line. To achieve greater bandwidth many vendors have incorporated proprietary methods to combine multiple ports to aggregate bandwidth. The link aggregation protocol (LACP) was devised by the IEEE to address this functionality.

Here are some examples of proprietary port aggregation methods you may come across.

  • Cisco - EtherChannel, Port Aggregation Protocol
  • Juniper - Aggregated Ethernet
  • Avaya - Multi-link Trunking, Split Multi-link Trunking, Distributed Multi-link Trunking
  • ZTE - Smartgroup
  • Huawei - Eth-Trunk

Port aggregation becomes important in your wireless hardware choices because 802.11ac Wave 1 and Wave 2 claim multigigabit throughput capabilities. To address the need for multigigabit throughput, the IEEE ratified the 802.3bz standard in September of 2016. Often called NBASE-T/MGBASE-T, the new standard allows for 2.5Gbps at 100m on Cat 5e cabling and 5Gbps at 100m on both Cat 5e and Cat 6/6a while also supporting PoE+. Implementations can vary by vendor.

Media Supported Switches can support all copper, all fiber, or a combination of both medias. One of the most commonly used switch orientations is multiple copper ports with expansion slots for copper or fiber modules. Copper ports utilize RJ-45 jacks to connect. Expansion modules for both copper and fiber support XFP, SFP, or SFP+ modules. SFP+ is the more common type of module used today in newer Ethernet equipment.

Power The ability to offer both data and power over a single cable was a major advance in Ethernet technologies. Newer switches have the ability to provide power from switch ports across the twisted pair Ethernet cabling to endpoint devices such as VOIP telephones and wireless access points. In 2003, the IEEE 802.3af-2003 standard was introduced and named Power over Ethernet (PoE). This standard provides 15.4 W of DC power on each port. PoE requires Cat5e or better for full power functionality with limits of 100m (330ft). In 2009, a new power standard IEEE 802.3at was created and name Power over Ethernet Plus (PoE+). This standard provides 25.5 W of power on each port up to 100m distance. While PoE+ will function over Cat5e cabling, Cat6a is highly recommended as industry tests have shown lower power dissipation resulting in more efficient delivery and cost savings. It is important note that some manufacturers will require both primary and redundant power supplies be used for 90% or more of the ports to provide power. Without both power supplies, only a limited number of ports provide power. Check with your vendor for more details.

Many of the newer wireless access points, especially 802.11ac Wave 2 require PoE+ for full functionality. Some ac Wave 1 access points will function fully using only PoE. Have a conversation with your vendor to confirm this functionality. Note that both physical cabling and switch capabilities can have a direct impact on your choice of wireless equipment and the optimal functionality of your wireless infrastructure.

Key components to consider when evaluating switches:

  • Copper uplink ports support IEEE 802.3an (10 Gbps)
  • Expansion ports support SFP+ modules either copper or fiber
  • Support for multiple VLANs
  • Support for at least 25.5 Watts of PoE+ on multiple 1 GbE ports simultaneously
  • Support for at least 15 Watts of PoE per port on 90% of 1GbE port simultaneously
  • Non-blocking switch backplane (internal bandwidth can handle all port bandwidth simultaneously at full capacity)
  • SNMP management capabilities
  • Vendor-specific management capabilities
  • Any lightweight Layer 3 switching/routing support
  • Whether the product can integrate with the existing install base
  • Does this product fit into a more holistic approach with other products?

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