How to configure and optimize your 2.4Ghz wireless network

[Anonymous]

This article provides instructions for:

• Configuring basic wireless network settings.
• Optimizing an 802.11n network to achieve optimum throughput, using the 2.4 GHz radios in SmartRG products.
• Upgrading from 802.11n to 802.11ac.

Also see How to configure and optimize your 5Ghz wireless network.

Use Case

At the beginning of summer, a group of college students rent an apartment and share costs on utilities including Internet service.  Everyone has the latest technology and enjoys high-demand activities like online gaming and sharing music and videos.

The students initially set up their SmartRG Gateway to achieve the highest possible throughput with the strongest form of password authentication, as follows:

• 40 MHz channel bonding
• WPA2-PSK authentication

At the end of the summer, Hector moves to the apartment down the hall. He sets up his own gateway in exactly the same manner. A few weeks later, a new roommate moves in with the group in the first apartment and is unable to connect to the wireless network using the credentials provided by his roommates. The new roommate is using an older laptop that only supports WPA-PSK and WEP but not WPA2-PSK.

Simultaneously, the other roommates notice the wireless network has become unreliable and very slow.

Learning Objectives

The objectives for this article are to:

1. Set up the students’ initial configuration for maximizing throughput using 40 MHz channel-bonding with the built-in 2.4 GHz radio.
2. Change the credentials required to access the network for situations such as a roommate moving out.
3. Change the network authentication mechanism to simultaneously support both older and newer technology when required.
4. Identify causes of wireless performance degradation.
5. Take remedial steps to address wireless performance degradation.
6. Set up dual radios: 802.11n at 2.4GHz and 802.11ac at 5GHz.

Preparation

Before proceeding, perform the two tasks listed in this section.

Determining whether your gateway supports 802.11ac

SmartRG models that support 802.11ac include the SR400, SR515, and SR555. If you are not sure whether your gateway supports 802.11ac, contact your service provider.

• If your gateway does not support 802.11ac, contact your service provider for an upgrade.
• If your gateway does support 802.11ac, continue with the instructions below.

Configure a Secure Wireless Network

1. Log in to the SmartRG gateway.
2. In the left navigation bar, click Wireless. The Wireless -- Basic page appears.
3. Verify that the Enable Wireless check box is selected.
4. In the SSID (Service Set Identification) field, enter “Pinto” (for this example). The SSID is also known as the wireless network name.
   For your network, choose an intuitive name that will help users identify their own wireless network when browsing for available networks from their client device.
5. Click Apply/Save at the bottom of the page to commit your changes.
6. In the left navigation, click Wireless > Security. The Wireless –- Security page appears.
7. Scroll down to Network Authentication and select WPA2-PSK from the drop-down menu.
8. Enter a WPA Passphrase. Choose a passphrase that is not easy for unauthorized users to guess. The requirements for passphrases are:
   
   • 8-12 characters in length.
   • A mix of upper and lower case letters.
   • Numbers and symbols are permitted and encouraged.
9. Click Apply/Save to commit your changes.

1.  Maximizing Throughput using 40 MHz Channel-Bonding

Selecting 40 MHz channel-bonding effectively doubles the speed at which the gateway will transfer data to and from a wireless client. The default setting is a single 20 MHz channel which has a maximum data transfer rate of 130 – 144 Mbps (which varies due to signal strength and other environmental factors). With channel-bonding selected, the data transfer rate can rise to 270 – 300 Mbps. The major drawback of 40 MHz channel-bonding with the built in 2.4 GHz radios is the limited radio spectrum allocated for 802.11-based wireless networks. Since the same radio spectrum is re-used from home to home and business to business, the radio spectrum can become congested. Normally, if there is a lot of interference for a client operating on a given 20 MHz channel, the gateway will scan for a channel with less interference or congestion and switch to that channel. When channel-bonding is implemented, there are fewer channel choices because of the need for an upper-sideband or a lower-sideband channels for control as well as the two 20MHz channels required for bonding. Contrast this with the 11+ channels available with 20 MHz operation.

Note: It is recommended that you implement channel-bonding only in environments without multiple access points or gateways operating in close proximity.

Configuring 40 MHz Channel Bonding

1. In the left navigation menu, click Wireless > Advanced.
2. Set the options listed in the table below and leave the other fields set to their defaults.
3. Click Apply/Save to commit your changes.

Field	Description
Control Sideband	When you select Lower, the radio uses channels 1-7. When you select Upper, the radio uses channels 5-13.Lower works for most scenarios. If there are other access points located nearby that use channels 1-7, select Upper.
Channel	Select the channel (radio frequency) on which the gateway operates. If Sideband is set to Lower, select 1. If Sideband is set to Upper, select 5.
Bandwidth	Sets the channel width or number of channels on which the gateway will operate.Select 40 MHz.
802.11n Protection	The 802.11n standards provide a method of allowing 802.11g and 802.11b clients to operate in the same network despite operating at different data rates by preventing them from transmitting at the same time. Shutting this option off results in allowing only 802.11n clients to connect; this is known as greenfield mode.Select Off.
802.11n Client Only	Enable or disable support for 802.11 and 802.11g clients. Select On.
OBSS Coexistence	Determines whether 20 and 40 MHz clients are permitted to operate within the same frequency range.Select Disable.

2. & 3. Changing the Wireless Network Passphrase & Authentication Method

You should change the wireless network passphrase routinely but especially when an event like Hector moving out takes place. There are many methods employed by malicious users to guess wireless network passphrase including automated methods that make guesses based upon dictionary words or colloquial terms, so it is best to use a passphrase that utilizes a creative mix of all the types of allowable characters described above. The new roommate’s laptop does not support WPA2-PSK authentication so it makes sense to use a different authentication type that works for all of the roommates’ devices. The solution for his device to co-exist with the others is to employ Mixed WPA-PSK and WPA2-PSK authentication.

For Mixed WPA-PSK and WPA2-PSK

1. In the left navigation menu, click Wireless > Security. The Wireless –- Security page appears.
2. If Network Authentication is not set to Mixed WPA-PSK and WPA2-PSK, select it now.
3. In the WPA Passphrase field, type in the new password. The Passphrase field appears.
4. (Optional) Click Use the base MAC address as the password. The passphrase field is populated with the MAC address for the gateway. The base MAC address can also be found on the label affixed to the gateway.
5. Click Apply/Save to commit your changes.
6. Verify that the passphrase typed and saved correctly by clicking Click here to display.

4: Identifying Causes of Degraded Wireless Performance

Common symptoms of wireless performance degradation include the network name not appearing consistently and slow wireless speeds. Common causes of these symptoms are listed below.

Issue	Typical Causes
Network name (SSID) not appearing or appearing sporadically	The wireless network is not enabled in the gateway. The gateway was configured not to broadcast an SSID beacon to hide the network. The client is too far away from the gateway. The client does not support the wireless protocol used by the gateway, e.g. an 802.11b client may not see 802.11n beacons if the gateway is operating exclusively in 802.11n mode. Congestion due to too many modems, gateways or access points operating on the same frequency/channel ranges in close proximity to each other.
Slow wireless speeds	The rate at which the gateway and the client negotiate is dependent upon their supported speeds. e.g. A client that supports only 802.11b will not be able to negotiate speeds higher than 11 Mbps whereas a client that supports 802.11n is fully capable of achieving speeds of 270 – 300 Mbps with channel bonding enabled. Poor signal strength can affect both the speed at which the client and gateway negotiate as well as reduce the actual throughput due to packets lost in transmission. This slows the network down considerably as things become less and less efficient due to retransmission attempts for the lost packets. Received signal strength is inversely proportionate to the inverse squared distance to the source. In other words, each time the distance between a given client and gateway is doubled, the received signal is ¼ of what it was at the previous location. Congestion and Interference is the result of too many gateways, or access points operating on the same frequency/channel ranges in close proximity to each other.

5: Resolving Wireless Performance Issues

The use case provides an example of a situation where performance is suffering and the likely cause is interference and/or congestion. The wireless network was working fine until Hector moved to a nearby space and set up his own wireless network in exactly the same manner as his friends, using 2.4 GHz and channel-bonding. Once the semester started, the surrounding rental spaces filled up and the many additional networks are clogging the wi-fi airspace. It may be possible to minimize congestion and interference by determining the best frequency/channel to operate on.

Determining optimal frequency/channel settings

1. Download and install a wireless spectrum analyzer for 802.11 networks. InSSIDer is a good tool for analyzing wireless networks and a free trial can be downloaded from the metageek site.
2. Launch the InSSIDer application.
3. Click the Networks tab at the top of the page.
4. Select the name of your wireless network in the list.
5. On the right side, at the top of the graph, click the Star icon next to the SSID name.
6. Click the Analyze tab. This page displays the recommended, least congested channel and various metrics. Pay attention to the Link Score value. 100 is the best possible score.

Example

From the screenshot below, it’s clear that the original group of roommates and Hector all have wireless networks operating on the exact same frequencies/channels (Channels 1+5).

If you change the radio settings to operate in the Upper Sideband instead of the Lower Sideband, the link score improves from 34 to 44.

6: Enhancing Wireless Performance by Upgrading to an 802.11ac-Capable Gateway

In densely populated areas, or in multi-tenant dwellings (such as the situation presented in the use case), it may not be possible to find a clear channel within the 2.4GHz band. By upgrading to a SmartRG Gateway that supports 802.11ac, you may be able to minimize congestion and interference by allowing clients that support 802.11ac to connect using the 5GHz band while still providing support for clients that can only operate at 2.4GHz.

Setting up 802.11ac Support on the 5GHz Radio

1. Make sure that the 2.4Ghz radio is set up for 802.11n support. Instructions are provided in the "Objective 1" section earlier in this article.
2. Log in to the SmartRG gateway.
3. Configure the 5GHz radio:
   1. In the left navigation menu, click Wireless > 5GHz Band. The Wireless -- Basic page appears.
   2. Verify that the Enable Wireless check box is selected.
   3. Set the SSID (Service Set Identification), which is commonly referred to as the wireless network name. For this example, we will use, “Pinto5GHz” for the SSID.
      Choose an intuitive name that will help users identify their own wireless network when browsing for available networks from their client device.
   4. Click Apply/Save to commit your changes.
   5. Secure the 5GHz network by following the instructions provided in the "Preparation" section earlier in this article.
   6. Set up advanced options to maximize throughput using 80MHz channels.
      1. In the left navigation menu, click Wireless > 5GHz Band > Advanced.
      2. Set the following options and leave all other settings at their default.
4. Click Apply/Save to commit your changes.

This task is completed.