Air-IQ software training презентация

Sample Application Code Walkthrough
Air-IQ AP Software Stack Integration Tasks
Building Air-IQ Software Stack
Troubleshooting and Debug
Common CSP Issues

AGENDA

spectrum analysis in the 2.4GHz and 5GHz bands
Air-IQ AP Software Stack
Utilizes the FFT and IQ capture capabilities of Broadcom IEEE 802.11ac Wireless LAN ICs to capture FFT data and IQ data
Detects and classifies interference from 17 different types of non-WiFi devices
Calculates and reports non-WiFi channel utilization and channel quality
Provides Broadcom Signal Analyzer (BSA) API for accessing spectrum analysis data, events, and reports
Simple User interface for displaying interference events, channel quality, and non-WiFi channel utilization
Air-IQ RF Monitor Service
Provides centralized monitoring of up to 1500 Air-IQ enabled APs
Provides advanced spectrum analysis capabilities like:
Interference event clustering
Interference source localization
Spectral data recording/playback
Provides Broadcom Monitor Service (BMS) API for accessing all spectrum information for monitored APs
Air-IQ Monitor Console
User Interface for managing and displaying spectrum information collected by Monitor Service
Designed to be integrated into Web UI of WLAN controller and/or network management appliance.

WHAT IS AIR-IQ?

Stack

Air-IQ Scanning Application (airiq_app)

WL Driver

Air-IQ AP GUI (LocalApp.swf)

RF Monitoring Service
(monitor_service)

TCP/IP Stack

NIC Driver

OEM SW

RF Monitoring Console
(ComboApp.swf)

Management PC

TCP/IP Stack

Air-IQ SIRP Client
(libairiq_sirp.so)

NIC Driver

Air-IQ Core Library
(libairiq.so)

types of interference
-85dBm sensitivity (typical)
20s time to classify (typical dedicated mode)
Non-WiFi channel utilization and channel quality reports
FFT data for spectral displays
Analysis specs
20/40/80MHz analysis bandwidths
256pt FFT captured every 100-200µs
312.5KHz resolution
10-50ms channel dwell time (typical)
Spectrum Analysis Modes
Dedicated Mode
Radio is dedicated to spectrum analysis.
No Wi-Fi access.
Fastest classification times
Hybrid Mode
Radio is time sliced between Wi-Fi access and Spectrum Analysis
Low-duty-factor spectrum analysis (1% typical, 50ms every 5s)
Minor impact to WLAN throughput
Longer classification times than other modes (especially frequency hoppers)
3+1 Mode (43465) and 2+1 Mode (434525)
3x3 provides Wi-Fi access, 1x1 provides spectrum analysis
3x3 and 1x1 can be in different bands and/or channels.
Fast classification times

AIRIQ AP SOFTWARE FEATURES AND PERFORMANCE

shows current channel quality and non-Wi-Fi channel utilization for all channels scanned
Interference log shows list of recent interference events detected by the AP with details on each event

local displays

RF Monitoring Console

RF Monitoring Service

Centralized Databases:
Interference Reports
Spectral Recordings

Centralized Monitoring
Advanced RF Displays

User Alerts
Consolidated Reports

Historical Database Analysis
Record / Playback

Interferer reports
Channel quality reports
FFT-data for spectral displays

Air-IQ information:
Interferer Reports:
Type of Interferer
Center Frequency
RSSI of Interference Signal (Max, Ave, Current)
Channels affected by interference
Duty Cycle of interference
Channel Quality Reports:
WLAN Channel Utilization
Non-WLAN Channel Utilization
Channel Quality / Rankings
FFT data for spectral displays / recordings

BMS API

Communication
Management

Alerts
Management

Database
Management

Source
Localization

the RF Monitoring Service, including the interference/event database, the FFT data for spectral displays and the database for advanced spectral recordings
Provides remote and centralized configurability of APs for scheduled and alert-triggered spectral recordings
Displays include:

Statistics Dashboard Display
Interference and Event Log
Recording Log
Channel Quality Display
Channel Utilization Display
Channel Utilization vs. Time Display
Scrolling Spectrogram with interference classification overlays
Spectrum Analyzer Display
Persistence Display

Log

Components
WL driver with Air-IQ WL Module
Air-IQ Core Library
Air-IQ Service
SIRP Client Library
Air-IQ Sample Scanning Application
Air-IQ Local Application
OEM applications (aka ‘User applications’) that access BSA API
Library Architecture Software Components
WL driver with Air-IQ WL Module
Air-IQ Core Library
Air-IQ Sample Scanning Application
OEM application that accesses BSA API

of WLAN IC required for spectrum analysis
Provides IOVAR interface for spectrum analysis
Spectrum analysis scanning configuration and control
Radio gain control
FFT data and interference event forwarding
Provided in source code format

of WLAN IC required for spectrum analysis
Provides IOVAR interface for spectrum analysis
Spectrum analysis scanning configuration and control
Radio gain control
FFT data and interference event forwarding
Provided in source code format
Air-IQ Core Library (libairiq.so)
Implements BSA API functionality.
Interfaces to Air-IQ WL module via WL IOVAR interface.
Performs interference classification signal processing of FFT data for WLAN ICs that do not support offload
Implemented as shared library
Provided in binary format (no source code)

on AP
Contains Spectrum Information Request Protocol (SIRP) Server
Enables simultaneous access to BSA API by multiple applications.
Enables access to BSA API by ‘remote’ applications via a TCP/IP network
Supports a maximum of 16 User applications
Provided in binary format (no source code)

on AP
Contains Spectrum Information Request Protocol (SIRP) Server
Enables simultaneous access to BSA API by multiple applications.
SIRP supports a maximum of User applications
Enables access to BSA API by ‘remote’ applications via a TCP/IP network
Provided in binary format (no source code)
SIRP Client Library (libairiq_sirp.so)
Provides BSA API access to User applications
Communicates to SIRP Server via TCP connection
Shared library dynamically linked to user application.
libairiq_sirp.so provided in binary format (no source code)

Spectrum Analysis UI
Interference Event Log (last 128 events)
Channel Quality Graph
Non-WiFi Channel Utilization graph
Designed to be embedded into AP’s web interface
Implemented as Adobe Flash Application.
Downloaded from AP to end user Web Browser
Runs in context of Web browser.
Provided in binary format (no source code)

WL Device Driver

Air-IQ WL Module

Air-IQ AP Software Stack

User
Application
(e.g. airiq_app)

Air-IQ Service
(airiq_service)

SIRP Server

Network Device

TCP/IP Network Stack

User Space

Kernel Space

HW

TCP/IP Network

SIRP Client
(libairiq_sirp.so)

Air-IQ Core
(libairiq.so)

BSA API

WLAN IC

BSA API

End User PC

Network Device

TCP/IP Network Stack

User Space

Kernel Space

HW

SIRP Client

BSA API

Network Stack

User Space

Kernel Space

HW

Air-IQ Core
(libairiq.so)

BSA API

WLAN IC

Air-IQ Library Architecture
User application dynamically links to Air-IQ core library
Does not use Air-IQ Service or SIRP Client Library
Benefits
Less complexity
Smaller memory footprint
Perhaps more secure since there is no network access to BSA API
OEM can use existing OEM specific network data transport to forward spectrum information to WLAN controller or Network management appliance.
Limitations
Only one application can access the BSA API
No remote access to BSA API via TCP/IP network
Cannot use Air-IQ Local Application UI

content from applications
Allows configuration of signal analyzer
Two ways to use BSA API:
Local
OEM can link their application with Air-IQ library (libairiq.so).
Uses IOVAR interface to WL driver.
Remote
SIRP = Spectrum Information Reporting Protocol.
SIRP ? Access to BSA API over TCP/IP using client/server model.
airiq_service binary application including SIRP server
On router, airiq_service server listens for SIRP connection requests.
OEM can link their application to SIRP client library (libairiq_sirp.so)

BSA API

Network Stack

User Space

Kernel Space

HW

TCP/IP Network

SIRP Client
(libairiq_sirp.so)

Air-IQ Core
(libairiq.so)

BSA API

BSA Device

BSA API

Air-IQ Remote Software Stack

Remote
BSA API
Application
(e.g. monitor_service)

Network Device

TCP/IP Network Stack

User Space

Kernel Space

HW

SIRP Client
(libairiq_sirp.so)

BSA API

BSA API IN AIR-IQ SOFTWARE STACK

interference. If interference is to be identified, the receiver must be tuned to a channel containing the interfering signal.
Air-IQ measures channel utilization on scanned channels.
Scan mode parameters determine classification performance.
Classification performance is highly dependent on scan mode parameters.
Given the numerous constraints applied to Air-IQ, including
CPU load and coexistence with Wi-Fi access
Imperfect receive gain control
Time-domain resolution
Non-continuous monitoring
Interference classification is a very tricky problem.
We recommend specific scan mode parameters in order to control interference classification behavior.
Deviating from qualified parameters can impact interference classification performance, such as missed detection or misclassifications.

AIR-IQ SCAN

set of parameters in a scan.
There are many possible combinations/degrees of freedom for scan parameters.
We give the customer full control and flexibility, but try to guide them to
Air-IQ scans are configurable, but our team has a few typical modes of use.
Dedicated mode – Air-IQ uses the radio for a large duty cycle (so much that Wi-Fi traffic is not sustainable).
Time between scans: 1 second.
Capture more FFT’s on channels where there may be interference.
Useful when the customer has a radio that can be dedicated to scanning. 3rd radio?
Hybrid mode – Air-IQ scans are throttled to permit a radio to primarily serve clients while occasionally scanning.
Time between scans slowed for 5 GHz: 1 scan / 5 seconds.
Capture fewer FFT’s per channel, dwelling only 10 ms.
Useful on AP’s without dedicated scan radio.
43465/43525 supports 3x3+1/2x2+1 mode, where radio #3 can perform scanning simultaneously to Wi-Fi traffic**. This is bleeding edge and improving from release to release.
**Note: B1 chip has a bug that prevents this from happening without packet loss. C0 chip fixes this and is expected to improve simultaneous 3x3+1 Wi-Fi and Air-IQ performance.

HOW AIR-IQ SCANS

we provide.
Air-IQ scan requests are executed in the driver similar to ordinary Wi-Fi scans.
During an Air-IQ scan, other radio functionality is suspended. This is why we try to perform them as quickly as possible.
Application software sets airiq_scan IOVAR and provides an airiq_config_t.
Which channels to scan, how much time, how many sweeps, FFT count and spacing?
typedef struct {
int16 start; Do it (or not)
int16 chanspec_cnt; Number of channels to scan, length of the arrays below
int16 sweep_cnt; Number of sweeps, or 0 for infinite
uint16 dwell_interval_ms[MAX_CHANSPECS]; Length of time (milliseconds) to driver to dwell on each channel
uint16 fft_interval_us[MAX_CHANSPECS]; FFT capture interval (microseconds) – Depends on several factors
chanspec_t chanspec_list[MAX_CHANSPECS]; List of chanspecs to scan
uint32 capture_count[MAX_CHANSPECS]; Number of FFT’s to capture on each channel.
uint8 core_config[MAX_CHANSPECS]; Which MIMO RX core to use for each channel?
uint16 phy_mode; Selects 3x3+1 mode (30) and HW FFT mode (0)
} airiq_config_t;

HOW AIR-IQ SCANS

SCANS

Dwell intervals are precise to +/-10 milliseconds, due to Linux kernel timer scheduling.
Typically we use 10 ms for channels where there is little known a-priori interference. (e.g. most 5 GHz channels except UNII 3)
2.4 GHz and UNII-3 have the vast majority of non-WiFi interference. We scan for 40-50ms to improve detection probability
capture_count should be less than 1000*dwell_interval_ms/ fft_interval_us.
By limiting FFT capture count, we budget time for channel changes and limit CPU load.

use 0-2.
47452 in MIMO mode can use 0-1. In RSDB mode, use core 0. The RSDB wl interface number selects the antenna.
43465
(preliminary) HW mode FFT only works on core 0. Cores 1-3 give bad data. Seems like a chip bug. JIRA WLAN-2704.
3x3+1 VASIP FFT can only use core 3.
phy_mode – Selects between HW FFT and 3x3+1 VASIP FFT
Use value 30 for 3x3+1 VASIP FFT (or 2x2+1 on BCM43525)
Use value 0 for HW FFT. Expected to be used in 4x4 mode for BCM43465 and 3x3 mode for BCM43525.

HOW AIR-IQ SCANS

47452, 43465.
43465 has more options.
3x3+1 mode. Received waveforms are captured in time-domain using SVMP sample collect. VASIP PHYDSP firmware calculates FFT.
Air-IQ classification and FFT processing can be offloaded to onboard A7 core.
This is controlled by bit 8 of the offloads IOVAR, for example: “wl offloads 0x100”.
When offloaded, FFT’s pass from PHY/MAC to A7 core for processing. Reduces CPU and interrupt processing load on host.

HOW AIR-IQ SCANS – VARIATIONS ACROSS CHIPS

modes.
Fundamentally, the mode switching code in Air-IQ is a copy of that used by background DFS (a.k.a. zero-wait DFS)
4x4 -> 3x3+1 downgrade is initiated when:
the radio is in 4x4 mode
An airiq_scan iovar is set with phy_mode = 30 and core_config=3.
Interface downgrade is not instantaneous. Existing TX packets are flushed over one or more beacon intervals. TBTT interrupts are used to trigger the mode change.
Because of the repetitive scanning nature of Air-IQ, when a scan has completed the interface is not automatically upgraded.
To restore the radio to 4x4 mode, an explicit ‘scan abort’ IOVAR must be set:
Set the IOVAR “airiq_scan_abort” to 1 programmatically.
You can also set this at the command line:
wl airiq_scan_abort 1

HOW AIR-IQ SCANS – 43465 3X3+1 MODE

defines per channel FFT capture time
-int defines FFT capture interval
Air-IQ duty cycle = (Capture time * num channels)/((Capture time * num channels)+Dwell time)

FFT #1

FFT #2

FFT #3

4 usec

4 usec

4 usec

1st channel

. . .

Air-IQ Scan

WiFi Access / WIDS / WIPS

. . .

Dwell time
(-d option)

2nd channel

Air-IQ Scan

Air-IQ Scan

3rd channel

. . .

4th channel

5th channel

WiFi Access / WIDS / WIPS

load on BCM58522 platform
<1% measured throughput loss on secondary radio

FFT #1

FFT #2

FFT #3

4 usec

4 usec

4 usec

2.4GHz 7/80
450 FFT’s (45 ms)

42/80

58/80

106/80

122/80

138/80

5 GHZ 155/80
450 FFT’s (45 ms)

. . .

dead time

dead time

dead time

dead time

dead time

Air-IQ Scan

WIDS/WIPS

Air-IQ Scan

WIDS/WIPS

Air-IQ Scan

. . .

WiFi Access / WIDS / WIPS

2% duty cycle (98% Wi-Fi time)
5 GHz: Air-IQ scans with 1.3% duty cycle (98.7% Wi-Fi time)
Negligible CPU load on BCM58522 platform

FFT #1

FFT #2

FFT #3

4 usec

4 usec

4 usec

2.4GHz 7/80
100 FFT’s (10 ms)

. . .

Scan

Home channel

Home channel

. . .

20 ms

Scan

Scan

2.4GHz 14/20
100 FFT’s (10 ms)

Throughput loss
2.4GHz: 3.4 - 4.2%
5GHz: approximately 1.5 - 3.5%

like dwell time, fftcount, capture time for each airiq_scan mode. Sets up scanning for multiple interfaces if necessary
Calls DoSwsaScan for each airiq_scan sweep
ConfigureSwsaScanParam
Configures channel list for each radio bandwidth (20/40/80MHz)
DoSwsaScan
Executes WL IOVAR to run a single sweep airiq_scan
AbortSwsaScan
Demonstrates how to abort an airiq_scan
Demonstrates key BSA APIs
ConnectToHost
Local/Remote connections to device
RegisterForEvents
Registering for FFT, Interference and Channel Utilization events
AggrFftHandler
Callback function for Aggregate FFT event messages
InterferenceHandler
Callback function for Interference event messages
ChanUtilHandler
Callback function for channel utilization event messages
ScanCompleteHandler
Call back function for scan completion event

AIRIQ_APP

is used to demonstrate Air-IQ with the Air-IQ library architecture
“AIRIQ_APP_SIRP” macro is used to demonstrate Air-IQ with the Air-IQ Service architecture

AIRIQ_APP

of WLAN interfaces that can be used by Air-IQ Core Library
Air-IQ Core Library looks for airiq.cfg in following directory order: current directory, /etc, /, and /bin
Default linux network device names are “eth1”, “eth2”, and “eth3”
Linux network device names in airiq.cfg must match names used by OEM AP platform
Review/modify /etc/airiq_service.cfg parameter settings (Service Architecture only)
Contains parameters settings for Air-IQ Service
airiq_service.cfg must be located in /etc directory on AP filesystem
Parameters:
Daemonize – Determines whether service runs a daemon process or foreground process.
ListenPort – TCP port# airiq_service listens on for SIRP protocol connections. Default is TCP port 38182.
LogToFile – Determines whether or not airiq_service output is logged to a file.
LogFileName – Log file path and filename.

AIR-IQ AP SOFTWARE STACK INTEGRATION TASKS

ESDK and WL driver
Required files
/usr/lib/libariq.so,
/etc/airiq.cfg
/usr/sbin/airiq_app ( or OEM’s equivalent application )
Service Architecture only
/usr/sbin/airiq_service
/usr/sbin/airiq_service.cfg
/usr/lib/libairiq_sirp.so
Optional: LocalApp.swf
Modify AP initialization scripts to start Air-IQ service binary
Add ability to AP’s CLI/WEB User interface to configure Air-IQ
Configuration on per WLAN interface basis
Mode: Disabled, dedicated, hybrid, 3+1 mode
Scan Bands/Channels
Start/stop Air-IQ scanning application with appropriate scanning parameters based on the Air-IQ configuration

AIR-IQ AP SOFTWARE STACK INTEGRATION TASKS

UI.
LocalApp.swf binary
Typically requires 100-200 lines of HTML ‘wrapper’
Example HTML wrapper available on request.
Optional: Modify AP WLAN management interfaces(e.g. SNMP, REST API, etc.) to report spectrum analysis interference and channel utilization events received from BSA API

AIR-IQ AP SOFTWARE STACK INTEGRATION TASKS

data: every 1 sec
Interference data: every 5 secs
Channel Utilization data: every 5 secs
How many bins per FFT message
BSA_EVENT_ID_FFT_DATA:
Returns event message for each 20/40/80MHz channel
20MHz FFT – 64 bins; 40MHz FFT – 128 bins; 80MHz FFT – 256 bins
BSA_EVENT_ID_AGGR_FFT_DATA:
Returns event message for all channels in one band (2.4GHz, 5GHz low, 5GHz mid, 5GHz high)
Number of bins depends on radio bandwidth and start/stop frequency
FFT resolution is same 312.5KHz per bin
Can we get the Air-IQ displays directly from local system?   
Air-IQ displays are not part of ESDK distribution
Air-IQ displays are flash applications designed to be integrated quickly and seamlessly into customer existing web GUI on either an AP or a network appliance.  

COMMON CSP - AIR-IQ FAQ

scan CPU 1
3+1 mode: < 10% on scan CPU 1
How many threads are used by airiq library/airiq_service
Air-IQ Core Library uses 4 threads
Air-IQ Service uses 12 threads
How much memory does Air-IQ use?
Driver uses ~4MB
Classification issues
For any classification issues force customer to use “Classification Debug Capture” tool
Most common setup issues
Antennas side-by side touching, or lying on the PCB itself. Make sure to mount antennas on a backing plate
Antennas/AP placed near other electronic equipment
We expect in an enterprise deployment AP’s to be mounted on walls, ceilings, poles, etc, but not immediately next to another AP or desktop computer. Place the DUT a reasonable distance from other electronic equipment that may unintentionally radiate.
Air-IQ is sensitive to interference (its purpose) and it will pick up unintentional RF emissions from these devices when placed very close by.
Bad U.FL cables, or no antennas attached at all will cause us grief.
Check U.FL cables and antennae if Air-IQ reports interference while nothing is turned on.
It’s common to have bad U.FL cables or antenna
While testing Bluetooth ensure that music/data is streaming to headphones/bluetooth device.
While testing Microwave Oven make sure something is cooking! Place a bowl of water in the oven.

COMMON CSP – PERFORMANCE AND CLASSIFICATION