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As far as I know, essentially WIFI direct is enabled by a soft AP. My question: can the underlying WIFI module work as a WIFI station and as a WIFI direct endpoint simultaneously? That means, we hope that the WIFI module can communicate with a mobile phone using WIFI direct, and at the same time connect to a router as a WIFI station. Is it possible? and how widely and strongly is this case supported in technology?

user2089612
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You can if your wifi driver supports multi-role. This feature, available in some wifi chip (e.g TI's wl1271), allows you to use one wifi chip for different roles.

We use this feature in one of our product to maintain an access point while still being able to connect to another wifi station at the same time. This product runs on Android 4.0.4 with a OMAP 3.0 Linux kernel.

For more informations on this you can check if such a driver exists for your chip and take a look at this post I created on Stackoverflow where I give the details of our implementation using our wireless chip.

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Halim Qarroum
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    Great answer! In my case, I use a Freescale i.MX28 processor (ARM9 core) and Linux 2.6 kernel. What do you think of how well the TI's wl1271 WIFI chips support this configuration in terms of software compatibility? As far as I know, TI chips address their own processor first, which makes me doubt more or less its compatibility with other vendors' processor. By the way, I hope the AP role can support WIFI direct. Is it possible ? Tks! – user2089612 Mar 22 '13 at 03:08
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    You are totally right, Ti's platform comes as a whole SoC leaving you no choice but using their hole thing. If you really need this feature I will suggest you to buy a range extender and see what kind of chip/SoC they're using, I suggest you to choose a wifi chip with 2 antennas (one for STA, the other for SoftAP), this will save you some big trouble. Wifi direct can be used in place of AP role, they are not exactly the same thing. Anyway if you're using a recent kernel with hostapd and a multi-role chip it should work without pain. – Halim Qarroum Mar 22 '13 at 07:38
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    It's worth noting that the Wi-Fi Direct specification says that you should be able to connect to a Wi-Fi Direct group and another normal access point at the same time, so this is definitely a feature that is dependent on the wifi chip, as this answer states. – Cypress Frankenfeld Apr 23 '14 at 22:06
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    @CypressFrankenfeld That's correct. Most hardware I've been working with (mostly Realtek chips) supports simultaneous connectivity to AP and to a Wi-Fi direct group. However, I've noted that while it seemed to work well, Wi-Fi Direct connectivity is highly deteriorated when using the "regular" connection to the AP. This is certainly due to the fact that the chip demultiplexes the packets on the same antenna, which is unfortunate, especially for application such as Miracast. – Halim Qarroum Apr 24 '14 at 07:23
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    Early year 2016 perspective on this topic: More and more Android devices support this in my testing. In the android 4.4 / 5.0 / 6.0 era of 2016. However, I have encountered at least one modern device that does NOT support it - the "Motorola E 2015 GSM" (SKU XT1527) that runs Android 5.1. It specifically gives a warming message when changing between WiFi Direct to WiFi client that both can't be used at same time. Where, often less expensive devices of the same generation (Blu Energy Studio II, running Android 5.0) works fine. Google Nexus 5 works fine on Android 4.4/5.0/6.0 with this ability. – RoundSparrow hilltx Mar 13 '16 at 02:14
  • @HalimQarroum, do you know if any chipsets / drivers support multiple concurrent P2P mode virtual devices? e.g. being a client in more than one group, and/or being a group owner of one group and a client in another? – Eric Anderson Feb 26 '18 at 21:20
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    @EricAnderson I don't, I assume you'd require two wireless chips, or a chip supporting multi-role and exposing 2 network interfaces. – Halim Qarroum Feb 26 '18 at 23:02