I know the purpose of softAP in WiFi.
While enabling the softAP WiFi playing a host role we cant activate to client role till deactivate the softAP.
Why we can't design the double role softAP, which means why can't we activate our WiFi to play client and host at same time ?
If we do, what kind of problem we happen to face, is't possible?
Because in GSM we are creating virtual multiplexing ports for data,call,SMS etc.., like wise why can't we develop any firmware do perform like this for WiFi?
Of course, it's possible and it exists for various NICs. It's more complex because double mode requires handling the coexistence of both links.
Microsoft added a feature called "Virtual Wi-Fi" to Windows 7 and later operating systems, which enabled a Wi-Fi card to act as both a Wi-Fi client and a wireless access point simultaneously. Although a relatively fresh concept, new computers with Windows 7 and above were now being released with "Virtual WiFi" as a default program, making personal computing less complicated without the need for a second device.
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I'm trying to establish a connection between my PC running Ubuntu and my iPhone via Bluetooth automatically when it becomes available, after being manually paired beforehand. I've seen this to be possible with certain peripherals, mainly audio. For example, my phone will automatically connect to a Bluetooth speaker when it is turned on and Bluetooth is active on my phone; another example is my phone automatically connects to my car's radio system via Bluetooth when I turn the car on.
I'm not able to connect my phone to my PC without first initiating the connection from the smartphone's Bluetooth menu. I'm thinking that I could possibly write an application for the PC to attempt to connect to the device every few minutes or something, but it seems that the phone needs to be the device to initiate the connection.
The only information that I need for what I'm trying to do ultimately is that the devices can pair successfully. Essentially I'm trying to build a sort of proximity trigger between my phone and my PC without using Wi-Fi and GPS - I can't use these for some specific reasons.
Is there any way to make this happen?
Yes this should be doable as long as you use the Background Processing feature for iOS apps. In the example I'll give below, we'll have the PC be the peripheral and the phone be the central, but you can really have it working either way. You will need to do the following:-
First initial connection needs to be performed in the foreground (this is due to iOS's background limitations).
On the iOS side, you need an application that acts as a central that scans and connects to the remove device (check this example as a starting point).
Upon connection, you need to bond with the PC. Bonding is important as it will prevent you from having to do the pairing again in the future. However, pairing/bonding is managed by the iPhone's OS so you cannot write it in your application, so the workaround is to have an encrypted characteristic on the PC side that will force the iPhone to bond (this is covered later).
On the PC side, you need to have a BlueZ script that acts as a peripheral that is always advertising. You can do this using bluetoothctl (check the examples here and here).
Before you start advertising, you need to have a GATT server on the PC side (to do this, check this example).
When registering characteristics, ensure that one of them has the encrypt-read property (you can find a full list of the properties here).
Now when you attempt to read this characteristic from the iOS side, the two devices should bond (make sure that your PC is bondable which you can do this via these commands).
Once the devices are paired, your iOS app needs to be working in the background constantly scanning and attempting to connect to the same peripheral (have a look at this and this example).
You can find more useful information at the links below:-
Getting started with Bluetooth Low Energy
The Ultimate Guide to CoreBluetooth Development
How to manage Bluetooth devices on Linux using bluetoothctl
I have built a home surveillance and alarm system with raspberry pi's.
What I need now is an easy and safe remote control to arm the system and disarm it.
The most workable solution is to have a wireless router in the middle.
Before stepping out in the door, take out my phone, connect to my home network and via a custom built web page arm my system. (Web page would run the arming scripts)
But for this I need to have a wireless router (currently I have a non wireless Ubiquiti Router Station Pro, no radio card on it) and need to enable wireless on my phone (it is not enable-d, battery reasons) before leave, connect and so on. It is not one click unfortunately...
Other solution is to have just a wireless dongle in the Raspberry PI and do an Ad Hoc WiFi connection with my phone. My phone is Sony Ericson Xperia. Over here my technical knowledge hits the limit. It is possible to broadcast an Ad Hoc network over Raspberry PI I do not know if I can reach it from my Sony Ericson Xperia phone.
Third option is Bluetooth. I know very little about Bluetooth. I do not know how safe it is, and how to program it, to have on and off switch on my phone. However this might be the most promising.
Fourth option is to use the Pi Face. Link one or two switches to some type of receiver device. Have a sender device on my key chain and control it from there.
However I do not know from where I can buy such a safe remote control and if it is compatible with Pi Face.
Fifth option. To get home alarm system components and link those with the Pi Face. But I do not know what component might fit.
The best user scenario is the following.
User takes out out a device (phone or remote control) and presses arm/disarm.
User has appropriate time (30 sec) to get out or shut down.
If the remote device had run out from battery still have something to shut it down.
So my question does any body knows a fast, easy, cheap solution how to do this?
Though Bluetooth's security is questionable, it seems like the best option for your goal. Next to an adhoc
Bluetooth is not complicated.
On your mobile phone, if you don't want to make your own app you can look for some sort of Bluetooth Terminal or Bluetooth Chat. On your raspberry pi you'll have to setup a bluetooth rfcomm server with bluez.
How to configure Linux to act as a Bluetooth RFCOMM SPP server?
RFCOMM without pairing using PyBluez on Debian?
Modify these servers which do nothing by default, to listen for commends "arm" and "disarm". Make sure the ID of the device is the ID of your phone.
Ad-Hoc is even less complicated (assuming you know how to make a webserver and are going to make it secure enough, and have a dongle which supports adhoc):
Here is a post about ad-hoc networking with a raspberry pi.
In terms of distance, you'll have to see the specifications on your dongle(s) but I would say they're relatively the same.. your bluetooth dongle will have a class see Bluetooth Basics: Range. This will require more research but if you have either one of the dongles I would use that method.
I hope this helps, good luck setting up your alarm.
In the mean time I realized that a fast arming could be done via the Pi Face and pressing a button.
Disarming could go by other ways.
However the fastest solution would be a fingerprint button linked safely to Pi Face.
Updates. Finally went with the Ad-Hoc method:
This is the tutorial for it:
http://elinux.org/RPI-Wireless-Hotspot
I am Developing a Java ME Application. Here I am using WiFi Connection. Now My Question is how to get a particular WiFi Connections name using Java ME Code ?
My Requirement is for Nokia E5 Device only.
After doing much research work I found that this is not possible in Java ME Technology to fetch the WiFi Connection's Name.
However Similar Library would be com.nokia.multisim.networkid which returns Network ID and Network Short Name.
I Dont Think so it is 100% possible in J2ME and even though if it has worked and there is no guarantee that it will work on all J2ME devices which has Wifi connectivity.
most appropriate answer i have found , please go through it once.
" Much as I hate to put you through all that grief and then not have a simple answer, I don't have a simple answer.
The reason for that is because Java's networking model is based on TCP/IP, and the TCP/IP architecture is based on the idea that applications will neither know nor care about the hardware details of networking. A typical mobile device may contain several different network interfaces (WiFi, Bluetooth, Infrared, USB cable, and so forth), but when an app wants to contact another network node, the app doesn't know which of these interfaces is actually being used. And in fact, if the OS wants to do so, it can use more than one (in parallel) and/or switch interfaces in and out, based on routing criteria such as best measured data rates. Rather like how cell phones route phone calls.
So basic Java/JME won't know anything about WiFi.
However, there is an extension, specified as JSR 309 (http://jsp.org) that looks like it may help. It supports learning about and controlling the network interfaces themselves. The problem is that not all devices will implement this extension, so it will depend on what device(s) you are supporting. "
I need to connect to a Bluetooth device through virtual COM port created in Windows. It's easy when the port has been already created during manual pairing procedure. But I would like my application to relieve an user from the manual pairing of a device. I would like to present all devices in the range, allow user to chose one, and then create virtual COM port connected with the selected device. I'm not trying to avoid the pairing procedure itself, but rather I would like to invoke it by my application.
I started getting familiar with Microsoft Bluetooth API. And then some doubts arose. I've been wondering what happen if some user would use different (than Microsoft's) Bluetooth stack? Is the Microsoft's API the real Bluetooth API, which have to be implemented by any other Bluetooth stack provider? Or rather each provider has its own API, and the Microsoft's is only one of many other?
Thanks everyone for valuable input. I'd like to summarize what I've found so far. The Microsoft Bluetooth API is not operating system API. Application written against it will not cooperate correctly with any other Bluetooth stack. It seems that applications which are intended to cooperate with multiple stacks need to provide some stack abstraction layer, and stack specific code for all of them.The other solution is to allow user for manual pairing of the Bluetooth device, which eventually create some virtual device in the operating system (e.g., COM port). Then the application can use standard interface of such a device.
I can't speak for the Microsoft Bluetooth API, but there are multiple Bluetooth stacks available for the PC platform (even more for mobile devices).
The underlying API is defined by the Bluetooth Core Spec and so all stacks should be able to interact, in fact it is mandatory that they interop or they cannot use the Bluetooth name and logo.
As to pairing, your going to have a hard time getting devices to pair if they have default security, which requires a pin code.
Things might be simpler in the (near) future, as the Bluetooth standard has introduced a new security model, secure simple pairing, which has a 'just works' mode that requires no Pin code. This is still stronger then the current security, except against Man in the middle attacks. However, it could be a while before you see the chips with this feature in PCs.
If you can change to using .NET :-/ I can recommend our library 32feet.NET.
For explicit pairing there's BluetoothSecurity.PairDevice. We can also create the virtual port for you, for example:
BluetoothClient cli = new BluetoothClient();
BluetoothDeviceInfo[] list = cli.DiscoverDevices();
BluetoothDeviceInfo selected = GetUserToSelectOne(list);
BluetoothSecurity.PairDevice(selected, pin);
// Ask Win32 to create a virtual serial port
selected.SetServiceState(BluetoothService.SerialPort);
However I really don't like virtual serial ports so I always suggest that people use a normal sockets connection using our BluetoothClient class, it will automatically handle a pairing request if required.
On Win32 we support the stacks from Microsoft, Widcomm/Broadcom, and BlueSoleil. On Widcomm there's no support for SetServiceState there yet, and their API has no support for responding to pairing requests. BlueSoleil should support both.
A brief user's guide is at 32feet.NET — User’s Guide, and all the class documentation is available at the main site http://32feet.net, the Widcomm documentation is only in our code repository at the moment.
Midlet using HttpConnection to connect a webservice application.
A mobile can use a wireless broadband to connect to internet or can use internet facility provided by the network provider i.e. Vodafone or Virgin which is I think known as GPRS. Correct me if my understanding is wrong.
Now my question is when the midlet will run which connectivity it will use? Secondly do I need to code differently for midlet to use GPRS or it doesn't matter?
I deployed my application on Nokia E65 and it asked me which connection to use. The mobile had both wireless lan and provider GPRS active.
On IPhone the preference is for wireless lan. (Not related to J2me)
There is no standard Access Point Selection APi in J2ME.
That means the MIDlet itself can't decide whether to use Wi-Fi or GPRS.
Some phones will allow the user to change application settings in order to force a MIDlet to use a specific network when it is available (and maybe prompt the user for an alternative when the preferred network is not available).
This is mostly because there is no standard way to describe a wireless network that contains enough information : QoS, cost per byte downloaded and uploaded, average bitrate, ping time...
In most cases, the logic to automatically choose a network without those information would be too complicated and not reliable enough.
Manual Access Point selection is the only way to put the user in charge of the cost of data transfer, so far.
It depends on the client mobile phone. On some models, there is only one GPRS configuration that is used by all applications including midlets, On some others the configuration used for browsing can be different than the one used by midlets.