Wireless Range Extender 101

Wireless networking is ubiquitous in homes and businesses alike. The rise of devices that rely on these wireless networks – smart phones, tablets, smart TVs, gaming consoles, digital set top boxes and even thermostats – make wireless coverage throughout your home increasingly important. The quickest and easiest way to achieve this is through the use of a wireless range extender.

Wireless networks are often limited by the placement of the wireless router. Coverage in the far corners of the home, often bedrooms, can be weak or completely nonexistent.

Networks and the devices that connect to them have evolved greatly over the last decade. It used to be that stationary desktops were connected together through wires, while access points supported a handful of mobile devices. Now, HD video is being streamed to multiple wireless clients simultaneously in the far corners of the average home. These wireless network connections must deliver offer optimal performance in order to support the amount of bandwidth consumed by streaming content, as well as the range and reliability needed to reach tablets and set-top boxes.

Frequencies

By definition, the 802.11ac standard improves range and bandwidth by offering dual-band support, beamforming and improved performance over its predecessors. (You can get more information on the technical aspects of 802.11ac in our story on 802.11ac-capable routers.) Just remember that optimal performance on ac's 5GHz band requires a strong signal, which limits range compared to 2.4GHz. A potential solution to this conundrum is to implement an 802.11ac-capable wireless range extender, which will expand the reach of your network to the dark corners of your home.

802.11ac range extenders support 2.4 and 5GHz, both for connecting to existing wireless networks and ensuring client connectivity. In most cases, range extenders pass network traffic using the wireless client's band – 2.4GHz devices naturally go through the 2.4GHz connection and 5GHz clients through a 5GHz link to the router (though in some cases you can configure the range extender to use one band or clients and the other for connectivity back to the router). 802.11ac range extenders, like wireless routers and other Wi-Fi hardware, are marketed based on their advertised data rates. AC750 devices support 300Mb/s through 2.4GHz and 433Mb/s using the 5GHz signal, while AC1200 offers 300Mb/s for 2.4GHz and 867 Mb/s on 5GHz, though actual data rates are a fraction of those advertised rates.

802.11ac Speed Ratings

Type	2.4GHz Mb/s	5GHz Mb/s
AC600	150	433
AC750	300	450
AC1000	300	650
AC1200	300	867
AC1300	450	867
AC1450	450	975
AC1600	300	1300
AC1750	450	1300
AC1900	600	1300

Functionality And Placement

Range extenders are often physically similar to other wireless networking products you would typically find in a home or office, but they differ significantly in configuration and functionality. Wireless routers – perhaps the most common wireless networking product found in homes – connect directly to the broadband modem, sharing the Internet connection to wired and wireless devices, as well as providing basic network services like DHCP, NAT and a basic firewall. Access points also connect to existing wired networks, but simply provide access to an existing local network and its associated services. Wireless access points are often used in conjunction with an existing router – either wired or wireless – and wireless clients connect to the internet through this device.

Another type of wireless networking device is a media bridge, which allows a device without wireless connectivity to connect to a wireless network without having to run Ethernet cable. Media bridges connect to the wireless network as clients, and share the network connectivity through an RJ45 port. Range extenders share characteristics of both media bridges and wireless access points – connecting to an existing wireless network and then extending the wireless network as an access point and typically offering Ethernet connectivity as well. In most cases a router is needed on the network to provide DHCP and NAT, which allow network devices to reach the Internet.

A wireless range extender should be placed centrally, between the wireless router and potential wireless clients, in order to optimize the wireless signal throughout your home.

The physical placement of your wireless range extender will depend largely on the nature of your environment and the devices leveraging the expanded wireless footprint. A central location between the wireless router and wireless clients is ideal, however the location of wired computers could influence placement of the range extender as well. Other areas of potential interference like large metal objects should be avoided, as should large electronic devices. If your intent is to utilize 5GHz frequencies for optimal performance, you should remember that your range is more limited than 2.4GHz networks.

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Software And Firmware

Many modern hardware devices have embedded software, commonly known as firmware, which allows the manufacturer to patch bugs or add features. Some common examples of firmware you may be familiar with are cellular phone ROMs and your motherboard's BIOS. In most cases, firmware is read-only to the device, and specific steps must be followed in order to perform an upgrade. The read-only nature of firmware provides a layer of security by helping ensure malicious code doesn’t get applied to the device. Firmware updates should be handled with care, as misapplied firmware updates are a common reason for device failure (known as bricking).

In general, the biggest difference between a wireless range extender and a wireless router or access point is its firmware, as this determines the capabilities that are enabled on the device and ultimately drives the hardware. Unfortunately, firmware is rarely interchangeable between devices, so don’t plan on applying a router firmware to your range extender anytime soon.

For the adventurous types there is an open-source firmware alternative for Wi-Fi routers, which is beginning to offer support for range extender hardware. DD-WRT is a Linux distribution designed for use on wireless networking hardware. A list of supported devices is maintained on the project website, so check there in order to determine if your hardware is supported. If you’d prefer to re-purpose an old router to perform range extender duties, DD-WRT offers comparable functionality. Be aware that flashing a custom firmware to your device could potentially void your warranty.

Hardware

Range extenders commonly come in two form factors: devices designed to sit on a shelf or mount on a wall like a wireless access point or router, and those that mount directly on a power outlet. Both form factors offer some basic functionality that you can expect to find on any range extender. Antennas for the wireless network can be either internal or external, though external antennas can be expected to provide better signal. LED indicators are usually made available in order to be able to see the status of your network connectivity or provide other troubleshooting information.

Most range extenders designed to sit on a shelf offer connectivity for wired devices in the form of four or five gigabit Ethernet ports. Additionally, many of these devices provide a USB port to accommodate storage for file sharing or media server purposes, or even the option to share a USB printer on your network. Because of their size, these range extenders often provide increased performance over their outlet-mounted cousins through more robust processors or higher-powered amplifiers.

Outlet-mounted range extenders are often smaller in order to reduce weight and not place stress on the outlet. Because of size restrictions, these range extenders usually offer only one Ethernet port for wired devices and no USB port, and may not have the same performance capabilities as larger shelf-mounted units. What they give up in performance and capability they make up for in convenience. They're perfect for placing in a closet, hallway or behind furniture.

External And Internal Components

Most range extenders feature similar components – and often a similar form factor – as what you’d expect from a wireless router or access point. Many of the hardware features that make up a range extender are comparable across devices and vendors, but there are also features that only make an appearance occasionally.
In general, it’s safe to assume that a range extender will include core components like a processor and memory (both RAM and ROM) to store and run the device’s firmware, and to handle network traffic and other device functions. As with any piece of electronics, better performance from those components is always desirable, so some attention should be paid to their specifications.
Another component always found in a wireless range extender is the radio that handle wireless communication. Dual-band range extenders that offer support for both 2.4 and 5 GHz frequencies will typically have a wireless chipset and one or more amplifiers for each frequency, as well as the antennas used to optimize the signal. The size and placement of the antennas often has an impact on signal strength, and can be a major selling point.

Interior shot of a Linksys RE6500 showing 1) antenna jacks, 2) heat sink for processor, 3) Ethernet switch ports, 4) power input and WPS button, 5) 3.5 mm audio port, 6) transformers, 7) memory, and 8) radio chipset. The router’s reset button and flash a

Externally, range extenders often provide at least one Ethernet port, but some models offer four to six ports for wired connectivity. USB ports are also common, though their usage can vary wildly between devices, facilitating media server functionality, file sharing or print serving. Other options available on some range extenders include audio outputs for streaming music or other I/O like eSATA.
Some range extenders have on/off buttons, though others automatically power on when you plug them in. A button to enable the WPS feature (Wi-Fi Protected Setup) is common, as is a button (typically recessed) to reset the device to factory defaults.

Configuration

Most range extenders offer one of two configuration methods. The first and by far the simplest uses WPS (Wi-Fi Protected Setup), which involves pressing physical buttons on the wireless access point and range extender in order to securely pair the two devices. WPS provides easy setup but offers limited configuration options without further tweaking. Power users are better served walking through the manual configuration method, which typically involves a fairly straightforward setup process:

1. Connect your computer to the range extender using a wired or wireless interface.
2. Access the configuration website by name or IP address.
3. Configure the range extender to connect to your existing wireless network – preferably using both 2.4 and 5GHz connections.
4. Set up a new SSID for both frequencies.
5. Connect your wireless clients to the new range extender SSIDs.

The most difficult step in configuring your range extender is usually connecting to the configuration page, particularly after the device has been connected to your network and it pulls an IP address using DHCP. Most range extenders offer a method of connecting to your range extender without having to guess at the IP address. One of the most common methods used to provide access to your range extender configuration is using a DNS domain name (such as myrangeextender.com) that resolves only if your computer is connected to the range extender. Other devices use the Universal Plug and Play (UPnP) standard, which allows your computer to recognize the range extender as a configurable wireless networking device. In some cases, you may have to look through your router’s DHCP client table, but you should consult your range extender’s documentation in order to determine the preferred method of accessing the configuration page.

Screenshot of the configuration page for a Netgear EX6200 WiFi Range Extender. Note that both the 2.4 GHz and the 5 GHz networks are being extended.

It’s worth noting that a wireless range extender functions differently than an access point configured using Wireless Distribution System (WDS). WDS functions at a lower level – using the devices radios but not Wi-Fi – and is typically vendor-specific. Wireless range extenders use existing Wi-Fi networks, allowing them to support connection to any wireless access point that supports the proper bands.

The Future

It’s interesting to consider how extenders will fare in the future. Designed to make up for the range-related shortcomings of Wi-Fi, it doesn’t seem that extenders will be going anywhere in the short term thanks to WiGig. Considered an in-room technology, WiGig, also known 802.11ad, may have transfer speeds of up to 7 Gb/s, but throughput suffers dramatically as soon as you step out of a room. Because of this range limitation, 802.11ac will have a continuing role as a backbone for the home network, extending the need for Wi-Fi extenders, at least for a little while longer until 802.11ax comes along.
If anything, two current enterprise standards that are now in development for the consumer market, 802.11k and 802.11r, are being geared up to improve roaming between access points, routers and extenders. With current extenders, a second set of SSIDs is created so that the extender can service devices out of range of the main router, which works great for stationary wireless devices. However, roaming devices would need reassigned SSIDs to stay connected. Used together, 802.11k and r provide a service called Seamless Roaming; 802.11k lets the client device quickly identify and remember an available access point when a signal weakens, while 802.11k uses a feature called Fast Basic Service Set Transition (F-BSST) to streamline the authentication process between access points. Once established as a consumer feature, Seamless Roaming can eliminate the need of having more than one or two SSIDs.

Diagram showing how 802.11k and 802.11r can help wireless clients roam seamlessly.

 Another wireless networking technology that may have an impact on where extenders are used is mesh networking. Made up of small, individual networking nodes, mesh networks for the home are designed to produce reliable coverage. Each node in the network acts like a relay providing coverage for its particular zone and can back up a neighboring mesh node in case the latter stops working. The concept of mesh networking is not too new as it’s used in both enterprise and metropolitan environments. However, home usage is still in its infancy. If priced correctly and the performance is competitive enough, we can see mesh networking, in one form or another, affecting the Wi-Fi extender market.

Source : tomshardware

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