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Network Radar 2.4

Bluetooth devices intended for use in short-range personal area networks operate from 2.4 to 2.4835 GHz. To reduce interference with other protocols that use the 2.45 GHz band, the Bluetooth protocol divides the band into 80 channels (numbered from 0 to 79, each 1 MHz wide) and changes channels up to 1600 times per second. Newer Bluetooth versions also feature Adaptive Frequency Hopping which attempts to detect existing signals in the ISM band, such as Wi-Fi channels, and avoid them by negotiating a channel map between the communicating Bluetooth devices.

Network Radar 2.4

Different versions of Wi-Fi exist, with different ranges, radio bands and speeds. Wi-Fi most commonly uses the 2.4 gigahertz (12 cm) UHF and 5.8 gigahertz (5 cm) SHF ISM radio bands; these bands are subdivided into multiple channels. Each channel can be time-shared by multiple networks. These wavelengths work best for line-of-sight. Many common materials absorb or reflect them, which further restricts range, but can tend to help minimise interference between different networks in crowded environments. At close range, some versions of Wi-Fi, running on suitable hardware, can achieve speeds of over 1 Gbit/s.

Anyone within range with a wireless network interface controller can attempt to access a network; because of this, Wi-Fi is more vulnerable to attack (called eavesdropping) than wired networks. Wi-Fi Protected Access (WPA) is a family of technologies created to protect information moving across Wi-Fi networks and includes solutions for personal and enterprise networks. Security features of WPA have included stronger protections and new security practices as the security landscape has changed over time.

To avoid interference from IEEE 802.11 networks, an IEEE 802.15.4 network can be configured to only use channels 15, 20, 25, and 26, avoiding frequencies used by the commonly used IEEE 802.11 channels 1, 6, and 11. The exact channel selection depends on the local popular 802.11 channel. For example, in a place that uses 1, 7, and 13 channels, the preference would be for channels 15, 16, 21, and 22. Channel coexistence is possible provided 8 meters of spacing between the 802.11 access point and the 802.15.4 device.[5]

Video senders are a big problem for Wi-Fi networks. Unlike Wi-Fi they operate continuously, and are typically only 10 MHz in bandwidth. This causes a very intense signal as viewed on a spectrum analyser, and completely obliterates over half a channel. The result of this, typically in a Wireless Internet service provider-type environment, is that clients (who cannot hear the video sender due to the "hidden node" effect) can hear the Wi-Fi without any issues, but the receiver on the WISP's access point is completely obliterated by the video sender, so is extremely deaf. Furthermore, due to the nature of video senders, they are not interfered with by Wi-Fi easily, since the receiver and transmitter are typically located very close together, so the capture effect is very high. Wi-Fi also has a very wide spectrum, so only typically 30% of the peak power of the Wi-Fi actually affects the video sender. Wi-Fi is not continuous transmit, so the Wi-Fi signal interferes only intermittently with the video sender. A combination of these factors - low power output of the Wi-Fi compared to the video sender, the fact that typically the video sender is far closer to the receiver than the Wi-Fi transmitter and the FM capture effect means that a video sender may cause problems to Wi-Fi over a wide area, but the Wi-Fi unit causes few problems to the video sender.[citation needed]

In extreme cases, where the interference is either deliberate or all attempts to get rid of the offending device have proved futile, it may be possible to look at changing the parameters of the network. Changing collinear antennas for high gain directional dishes normally works very well, since the narrow beam from a high gain dish will not physically "see" the interference. Often sector antennae have sharp "nulls" in their vertical pattern, so changing the tilt angle of sector antennas with a spectrum analyzer connected to monitor the strength of the interference can place the offending device within the null of the sector. High gain antennas on the transmitter end can "overpower" the interference, although their use may cause the effective radiated power (ERP) of the signal to become too high, and so their use may not be legal.

Interference caused by a Wi-Fi network to its neighbors can be reduced by adding more base stations to that network. Every Wi-Fi standard provides for automatic adjustment of the data rate to channel conditions; poor links (usually those spanning greater distances) automatically operate at lower speeds. Deploying additional base stations around the coverage area of a network, particularly in existing areas of poor or no coverage, reduces the average distance between a wireless device and its nearest access point and increases the average speed. The same amount of data takes less time to send, reduces channel occupancy, and gives more idle time to neighboring networks, improving the performance of all networks concerned. However, there is a maximum number of base stations that can be added, after which they disrupt the network more than that they help: any additional capacity is then sapped by control traffic.[14]

The alternative of increasing coverage by adding an RF power amplifier to a single base station can bring similar improvements to a wireless network. The additional power offered by a linear amplifier will increase the signal-to-noise ratio at the client device, increasing the data rates used and reducing time spent transmitting data. The improved link quality will also reduce the number of retransmissions due to packet loss, further reducing channel occupancy. However, care must be taken to use a highly linear amplifier in order to avoid adding excessive noise to the signal.

All of the base stations in a wireless network should be set to the same SSID (which must be unique to all other networks within range) and plugged into the same logical Ethernet segment (one or more hubs or switches directly connected without IP routers). Wireless clients then automatically select the strongest access point from all those with the specified SSID, handing off from one to another as their relative signal strengths change. On many hardware and software implementations, this hand off can result in a short disruption in data transmission while the client and the new base station establish a connection. This potential disruption should be factored in when designing a network for low-latency services such as VoIP.

Auto RF samples data about the RF environment collected from each AP in a network and feeds it through a mathematical formula to derive an overall performance score for that particular AP. The product of all performance scores in the network then becomes the network's overall score, which is the ultimate factor when considering potential changes.

Each evaluation is run ten times, and once that cycle is complete, Auto RF will push any changes to the current channel and power settings that will result in a net increase to the network's performance score.

Auto Channel dynamically adjusts the channels of the client-serving radios to avoid RF interference (both 802.11 and non-802.11) and develops a channel plan for the wireless network. Auto Channel is a good fit for most wireless networks, providing a baseline channel configuration that can then be adjusted manually if needed.

Since DFS channels can only be used until radar communication is heard, disabling DFS may be useful if the wireless network is in close proximity to a harbor, airport, or weather radar station. Administrators may also want to disable DFS if most local wireless clients do not support DFS channels.

Many helicopters have radar systems that can trigger DFS events on wireless networks which would result in channel changes. Hospitals and other mission-critical locations that may have a helipad should consider excluding DFS channels. When a DFS event occurs, all the APs in a network will switch to the next best channel (disconnecting all clients on DFS channels) as per regulation requirements, which would be a non-DFS channel and then a DFS channel.

Meraki APs registered within the dashboard and out-of-network APs are considered in this metric. Meraki APs within the dashboard network are weighed higher to optimize roaming and airtime usage distribution. Rather than just counting and considering the number of overlapping networks, this metric ensures that the AP will coexist on a channel and have ample airtime availability.

Channel adjustments are made by the dashboard using information reported by the deployed APs. The dashboard will instruct an AP to change to a different channel for a number of reasons, such as when a new AP is added, the "Update Auto Channels" button is pressed, the radio channels get jammed, during the steady-state process, and during channel switch announcements. The APs in a network will use the information they have gathered from the environment and will calculate to see if there are any channels that have better performance. If an AP determines there are better channels, the AP will switch to it when the Auto Channels update every 15 minutes.

The dashboard will automatically adjust the channel on a new AP to a channel that is best optimized for the location where the AP is installed. The dashboard will collect information from the newly added AP and will select the channel that best fits within the existing wireless network.

Pressing the Update Auto Channels button on the radio settings page in the dashboard will force a one-time optimization of channels used by all APs within the dashboard network. This will usually result in a minute or two of downtime as the APs adjust their channel.

The steady state algorithm is client-aware. Auto RF will take into consideration metrics around channel utilization, channel width, associated devices, and traffic load for the 2.4 and 5 GHz radios of every AP in a network when determining optimal channel assignment for the APs in the network. 350c69d7ab

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