You are here: Adaptive Radio Management > ARM Overview
Previous TopicNext Topic

ARM Overview

Adaptive Radio Management (ARM) is a radio frequency management technology that optimizes WLAN performance even in the networks with highest traffic by dynamically and intelligently choosing the best 802.11 channel and transmitting power for each IAP in its current RF environment. ARM works with all standard clients, across all operating systems, while remaining in compliance with the IEEE 802.11 standards. It does not require any proprietary client software to achieve its performance goals. ARM ensures low-latency roaming, consistently high performance, and maximum client compatibility in a multi-channel environment. By ensuring the fair distribution of available Wi-Fi bandwidth to mobile devices, ARM ensures that data, voice, and video applications have sufficient network resources at all times. ARM allows mixed 802.11a, b, g, n, and ac client types to inter operate at the highest performance levels.

Channel or Power Assignment

The channel or power assignment feature automatically assigns channel and power settings for all the IAPs in the network according to changes in the RF environment. This feature automates many setup tasks during network installation and the ongoing operations when RF conditions change.

Voice Aware Scanning

The Voice Aware scanning feature prevents an IAP supporting an active voice call from scanning for other channels in the RF spectrum and allows n IAP to resume scanning when there are no active voice calls. This significantly improves the voice quality when a call is in progress and simultaneously delivers the automated RF management functions. By default, this feature is enabled.

Load Aware Scanning

The Load Aware Scanning feature dynamically adjusts scanning behavior to maintain uninterrupted data transfer on resource intensive systems when the network traffic exceeds a predefined threshold. The IAPs resume complete monitoring scans when the traffic drops to the normal levels. By default, this feature is enabled.

Band Steering Mode

The Band Steering feature assigns the dual-band capable clients to the 5 GHz band on dual-band IAPs. This feature reduces co-channel interference and increases available bandwidth for dual-band clients, because there are more channels on the 5 GHz band than on the 2.4 GHz band. For more information, Configuring ARM Features on an IAP.

Client Match

The ARM client match feature continually monitors a client's RF neighborhood to provide ongoing client bandsteering and load balancing, and enhanced AP reassignment for roaming mobile clients. This feature supersedes the legacy bandsteering and spectrum load balancing features, which, unlike client match, do not trigger IAP changes for clients already associated to an IAP.

 

Legacy 802.11a/b/g access points do not support the client match feature. When client match is enabled on 802.11n capable access points, the client match feature overrides any settings configured for the legacy bandsteering, station handoff assist or load balancing features. 802.11ac-capable access points do not support the legacy bandsteering, station hand off or load balancing settings, so these access points must be managed using client match.

When the client match feature is enabled on an IAP, the IAP measures the RF health of its associated clients. If one of the three mismatch conditions described below are met, clients are moved from one AP to another for better performance and client experience. In the current release, the client match feature is supported only within an IAP cluster.

The following client or IAP mismatch conditions are managed by the client match feature:

Dynamic Load Balancing: Client match balances clients across IAPs on different channels, based upon the client load on the IAPs and the SNR levels the client detects from an underutilized IAP. If an IAP radio can support additional clients, the IAP will participate in client match load balancing and clients can be directed to that IAP radio, subject to predefined SNR thresholds.
Sticky Clients: The client match feature also helps mobile clients that tend to stay associated to an IAP despite low signal levels. IAPs using client match continually monitor the client's RSSI as it roams between IAPs, and move the client to an IAP when a better radio match can be found. This prevents mobile clients from remaining associated to an APs with less than ideal RSSI, which can cause poor connectivity and reduce performance for other clients associated with that IAP.
Band Steering: IAPs using the client match feature monitor the RSSI for clients that advertise a dual-band capability. If a client is currently associated to a 2.4 GHz radio and the AP detects that the client has a good RSSI from the 5 GHz radio, the controller will attempt to steer the client to the 5 GHz radio, as long as the 5 GHz RSSI is not significantly worse than the 2.4 GHz RSSI, and the IAP retains a suitable distribution of clients on each of its radios.

By default, the client match feature is disabled. For information on client match configuration on an IAP, see Configuring ARM Features on an IAP.

 

In the Instant 6.3.1.1-4.0 release, spectrum load balancing is integrated with the client match feature. Client match allows the APs in a cluster to be divided into several logical AP RF neighborhood called domains, which share the same clients. The Virtual Controller determines the distribution of clients and balances client load across channels, regardless of whether the AP is responding to the wireless clients' probe requests.

Airtime Fairness Mode

The Airtime Fairness feature provides equal access to all clients on the wireless medium, regardless of client type, capability, or operating system, thus delivering uniform performance to all clients. This feature prevents the clients from monopolizing resources.

Access Point Control

The following access point control features are supported:

Customize Valid Channels — You can customize Valid 5 GHz channels and Valid 2.4 GHz channels for 20MHz and 40MHz channels in the IAP. The administrators can configure the ARM channels in the channel width window. The valid channels automatically show in the static channel assignment window.
Minimum Transmit Power — This indicates the minimum Effective Isotropic Radiated Power (EIRP) from 3 to 33 dBm in 3 dBm increments. You may also specify a special value of 127 dBm for regulatory maximum to disable power adjustments for environments such as outdoor mesh links. A higher power level setting may be constrained by the local regulatory requirements and AP capabilities. If the minimum transmission EIRP setting configured on an AP is not supported by the AP model, this value is reduced to the highest supported power setting. The default value is for minimum transmit power is 18 dBm.
Maximum Transmit Power — This indicates the maximum Effective Isotropic Radiated Power (EIRP) from 3 to 33 dBm in 3 dBm increments. Higher power level settings may be constrained by local regulatory requirements and AP capabilities. If the maximum transmission EIRP configured on an AP is not supported by the AP model, the value is reduced to the highest supported power setting. The default value for maximum transmit power is 127 dBm.
Client Aware — When Enabled, ARM does not change channels for the APs with active clients, except for high priority events such as radar or excessive noise. This feature must be enabled in most deployments for a stable WLAN. If the Client Aware mode is Disabled, the IAP may change to a more optimal channel, which change may disrupt current client traffic for a while. The Client Aware option is Enabled by default.

 

When the Client Aware ARM is disabled, channels can be changed even when the clients are active on a BSSID.

Scanning — When ARM is enabled, the IAP dynamically scans all 802.11 channels within its 802.11 regulatory domain at regular intervals and reports to the IAP. This scanning report includes WLAN coverage, interference, and intrusion detection data.
Wide Channel Bands — This feature allows administrators to configure 40 MHz channels in the 2.4 GHz and 5.0 GHz bands. 40 MHz channels are essentially two 20 MHz adjacent channels that are bonded together. 40 MHz channel effectively doubles the frequency bandwidth available for data transmission.

Monitoring the Network with ARM

When ARM is enabled, an IAP dynamically scans all 802.11 channels within its 802.11 regulatory domain at regular intervals and sends reports to a Virtual Controller on network (WLAN) coverage, interference, and intrusion detection.

ARM Metrics

ARM computes coverage and interference metrics for each valid channel and chooses the best performing channel and transmit power settings for each IAP RF environment. Each IAP gathers other metrics on its ARM-assigned channel to provide a snapshot of the current RF health state.