I am developing an android application and I would like to be able to control the range potency of my smartphone's wifi.
For example, suppose that I want to use the Wifi direct API, but I it shows me people that are in a range of 10 meters from me. Although this is very good, I just want to connect with people that are in a range of 3 meters from me. In this case my idea was to limit the potency of my smatphone's wifi, in order to only "see" the devices that are very near me.
My question in this case is: Is there anyway to limit/control the potency of the wifi device of my smartphone ?
The WifiManager exposes the public WifiManager.WifiLock createWifiLock (int lockType, String tag) method to allow for the application to claim a lock on the Wi-Fi in a certain mode, however, this is no mode that allow for the power to be decreased. So the answer to your question is no.
Related
Google introduced a set of limitations in Android 8 or 9 regarding Wi-Fi scanning frequency. Apps are restricted in how frequently they're able to scan for Wi-Fi connections, including P2P Wi-Fi peers. What is the situation with Wi-Fi Aware? Does it have the same limitation? Is it easier to bypass it?
This answer is as per the latest comments by OP.
One way to keep track of the RSSI of the network is to register for the intent RSSI_CHANGED_ACTION using a BroadcastReceiver and then extract the raw RSSI values from the Intent's extra values which are stored with the key Wi-FiManager.EXTRA_NEW_RSSI and obtain the threshold levels(usually the workable values) using calculateSignalLevel(). Some approximate code:
} else if (action.equals(WifiManager.RSSI_CHANGED_ACTION)) {
// Default to -200 as its below WifiManager.MIN_RSSI.
int rawRssi = intent.getIntExtra(WifiManager.EXTRA_NEW_RSSI, -200);
int rssiLevel = mWifiManager.calculateSignalLevel(rawRssi);
}
Also, to answer the previous question as to whether Wi-Fi aware is restricted by the same scan restrictions, the answer is 'no', not because it has a waiver vis-a-vis Wi-Fi-Direct but because it operates differently from a Wi-Fi-Direct connection. For a Wi-Fi Direct connection, one needs to make a request() to the WifiManager for initiating a scan and it is these scans that are throttled, with the duration of throttling varying based on whether the app is in foreground/background. This throttling can of course be overridden from the Developer Settings page.
Wi-Fi-Aware works with a different paradigm. If this is regarding the usage of ranging, then one can leverage Wi-Fi-Aware technology between two devices as follows:
Check whether ranging is supported using Wi-Fi-RTTI apis using context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_WIFI_RTT);
Check whether Wi-Fi RTT is available by registering for the intent WifiRttManager.ACTION_WIFI_RTT_STATE_CHANGED and on its receipt, check for whether Wi-Fi RTT is available.
Create a ranging request
Start ranging
Extract rssi from a successful ranging result.
One thing to note is that the requests for ranging are limited to 20 from each UID as per this code from the framework.
static final int MAX_QUEUED_PER_UID = 20;
Note that if you're running as a regular application, your app would have its own UID.
Have you ever seen the apple watch unlock a Mac? The idea is amazing, but I don't want a smart watch because I already have a phone which has similar capabilities AFAIK.
Also, I moved from OSX to Linux recently :)
I don't know how the Apple watch manages to unlock the Mac. But I know what would be desirable from a user experience point of view:
Needs to unlock quicker than I type my password
Should work in absence of wifi/4G
Should be power efficient
RFID
RFID would be nice, but no laptops that I know embed RFID readers.
Bluetooth based proximity detection
The challenge with classic Bluetooth is the requirement to constantly scan for near devices to measure the signal strenght (RSSI) from which we can infer the proximity.
Unfortunately discovery hops and listens 40 channels. And anyway the phones stop broadcasting when screen is off for a while. This is not good enough. I know because I tried:
import collection.JavaConverters._
import tinyb._
object Listener extends App {
var running = true
val BT_ADDR = sys.env.getOrElse("BT_ADDR", "XX:XX:XX:XX:XX:XX")
val BT_RSSI_DBM_THRESHOLD = Integer.parseInt(sys.env.getOrElse("BT_RSSI_DBM_THRESHOLD", "-65")).toShort
val manager = BluetoothManager.getBluetoothManager
val lock = new Object
while (true) {
manager.getAdapters.forEach(a => {
a.setRssiDiscoveryFilter(BT_RSSI_DBM_THRESHOLD)
a.removeDevices()
})
System.err.println("scanning for " + BT_ADDR + " at minimum " + BT_RSSI_DBM_THRESHOLD + " dBm RSSI...")
manager.startNearbyDiscovery(
(device: BluetoothDevice) => {
if (BT_ADDR.equals(device.getAddress)) {
onProximity(device)
manager.stopNearbyDiscovery()
lock.synchronized(lock.notify())
}
else println(device.getName)
}
, 1000
, false
)
lock.synchronized(lock.wait())
}
}
I was looking at BTLE (Bluetooth Low Energy), and I'm having difficulty to understand the following:
Is there a way to establish from Linux a single low energy bluetooth connection to the Android phone which we can leave dormant all the time, and use it to wake the phone up and make it transmit some packets (so we can measure its RSSI power and infer proximity) on demand, only when strictly needed.
I.e. we'd limit transmissions to only these rare occasions:
Check when the user is away if we detect inactive mouse & keyboard for 1 minute,
Check if the user is near enough when GDM is active
No BT activity whatsoever otherwise
This approach is quick, energy efficient, and does not require network protocol, only some rare BT transmission.
But is this possible with Bluetooth LE? Any pointers to examples?
Yes this should be possible with Bluetooth Low Energy (with some caveats) as follows:-
You need a BlueZ script/C program to constantly scan for your Android device.
You need your phone's Bluetooth to always be turned on.
You will need to pair at least once so that your Linux machine recognizes the changeable Bluetooth address of your Android device (see referenced links).
The BlueZ script program should be written so that as soon as your Linux system goes to standby, the program is launched as a daemon or background process that just starts scanning for Android devices and read their RSSI values. If your device is found and the RSSI value indicates that it is within range, this process will signal the Linux OS to wake up.
The caveats:-
BLE is not ideal for positioning/locationing; you can probably detect
if you're a few metres away but it would be challenging to get an
accuracy of a few centimeters.
Your BlueZ script needs to be
constantly running as a daemon or background process, so if it is
somehow killed or is inactive when the device goes to sleep, this
will not work.
Bluetooth on your phone should be always on, which
shouldn't have a big impact on the battery life but is also not
recommended.
Some resources for you:-
Running Bluetooth applications in the background in Linux
Bluetooth Low Energy: A Primer
Getting Started with Bluetooth Low Energy
Introduction to BLE
Bluetooth LE Signal Strength in Linux
Should One Create a Bond with a Bluetooth LE Device
How to Detect Whether System is Going to Standby in Linux
Android Bluetooth Low Energy Overview
Using Bluetooth Low Energy in Linux Command Line
It will not be a straight forward process and you'll probably have to try and fail along the way, but it will be a learning experience and you should be able to achieve what you want in the end.
I hope this helps.
I a trying to understand and modify the BLE sample von Android.com, now I can discover my sample BLE Device (HTC Fetch) and now I want to understand all that GATT and BLE stuff.
What are Characteristics and what are Profile and what are Serivces and what do they mean in the Bluetooth Low Energy World? I used HTC Dev and found a Service and a Characteristics UUID.
https://www.htcdev.com/devcenter/opensense-sdk/bluetooth-smart/htc-fetch/
But I guess what I need is the Find Me Profile, cause for the first steps I only want to get the Find Me react to a Button click.
https://developer.bluetooth.org/gatt/profiles/Pages/ProfileViewer.aspx?u=org.bluetooth.profile.find_me.xml
How to implement this in my App?
When I understand everything I try Power and Proximity (reading RSSI and compare with defined range).
Can some one help me understanding Bluetooth LE?
Here's a related post
How to use the profile of PROXIMITY PROFILE,IMMEDIATE ALERT SERVICE and Find Me Profile in android 4.3 BLE?
Basically you can approximate a proximity level using tx+power - rssi or distance roughly with
d = (rssi-A)/-20 (where A = rssi at one meter) or simply use rssi mapping out ranges to display You could also initially base it on just the connection range and skip rssi.
As for the FindMe, simply write the low or high alert values to make it sound when you press a button in your app. For pressing a button on the device use the UUIDs shown in the documentation.
sample code for that device is forthcoming
Is there any way in Android to detect all available carrier networks in the area. I tried to search it from connectivity manager and it seems it only returns active network info. I also tried the telephony manager and it only returns signals and neighbor info of the active carrier (e.g. other signals of same carrier). I would like to create an app that will scan for available cell networks in every country -- like in Settings -- to choose my network when roaming.
as far as i know that is not possible, because you can only get the cell info of your SIM carrier, but we have a new method on TelephonyManager called getAllCellInfo ().
The problem is that method its only available on API Level 17, only available on devices with Jelly Bean (4.2).
Check this link for more information.
Even the getAllCellInfo function will never report "all networks" that are in the air at your location, simply because the phone will only listen to / measure on the frequencies / networks that the current serving cell tells it to measure on. Normally this means that it will only measure (and be able to report cells) from the same network as the phone is currently using.
If the phone has lost coverage from its "home PLMN" (home or selected network) it will however periodically do measurements in other frequencies to try to get back to it's "favourite network".
To be able to get lists of all present networks in your area you need to have another kind of device for example a "scanner", which never locks on to any cell, but continuously scans many frequencies to find cells from any network and any radio access technology (GSM/WCDMA LTE for example) within these frequencies.
Or continuously press the "select network" function...
/ Kenneth
I've got a problem. I'm developing an android application that scans for wireless accesspoints/routers. I've been testing a couple of devices and I'm getting scan rates of 2, 1, 0.5, 0.1 etc. scans per second.
My goal is to reach 10 scans per second because a router can send beacons 10 times a second. And we need this for our application.
Is there away to make this possible? Perhapse hack a rom and replace the wifi drivers? I've been looking in to this but I can't find anything about this frequentie inside the driver.
The driver used is BCM4329 driver, I can't find any datasheets of the BCM4329 so it's kinda hard to figure this out.
Thanks in advance.
flitjes
I'm not familiar with driver development but I know it's one of the hardest thing in computer science so unless you have good knowledge in linux kernel development I would forget about it.
Moreover, you still need to scan the 12 Wi-fi channels to be sure that you are detecting all access points. An access point broadcasts a beacon every 100ms * 12 channels = 1.2 seconds. Spending less time than that and you risk missing access points.
You don't need to change anything in the device driver, Android makes it available to you to scan for access points. See the documentation.
Although requesting that many scans will probably not be very good for the battery life and the responsiveness of your app...
Your assumption that beacon rate is 10 per second is incorrect. This is really an AP configuration parameter, although 10 per sec is default in most. Besides that, APs do not send beacons simultaneously, if this happens, it's called a collision and a back-off algorithm is used for retransmission. In addition, even scanning 10 times per second doesn't make it certain for you to capture all beacons, like was pointed out in the previous answers.
if u use 4339 driver, you could not set the scan rate in driver or android api which is fixed in 4339 firmware, scan is about all channels && time u spend on each channel, according to the 80211 spec, which is part of mac && phy. in this case u just need to get the beacon, so u should use passive scan and use fixed channel && MaxChannelTime u want.
u have to ask broadcom for speical fw to figure out your problem,
IEEE
Std 802.11-2012 page 978
10.1.4.2 Passive scanning
If the ScanType parameter indicates a passive scan, the STA shall listen to each channel scanned for no
longer than a maximum duration defined by the MaxChannelTime parameter.