A small doc that when typing at the end causing StackEdit to jump around

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title: Android Wireless Issues
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permalink: "/androidWirelessIssues/"
categories:
    - documentation
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   image_fullwidth: "header.png"
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Getting peer to peer working on Android has been and continues to be a heck of a challenge. This document outlines a number of major areas where we had issues/challenges with Android and explains our rationale for how we dealt with them.

# Discovery - Wi-Fi Direct vs BLE
One of the first problems we ran into is - how should two Android phones discover each other as a prelude to communicating? Originally we adopted Wi-Fi Direct's discovery infrastructure. Wi-Fi Direct discovery is a two phase process. First there is peer discovery in which a phone advertises its MAC, a phone type ID and a phone identifier (that we can't set programmatically). This is then followed by Wi-Fi Direct Service Discovery where a phone can advertise what services it uses. We like Wi-Fi Direct because support for Wi-Fi Direct has been in Android for quite some time and so in theory using Wi-Fi Direct meant we could perform discovery using older handsets.

After literally months of testing Wi-Fi Direct's discovery infrastructure against numerous Android phones we came to two conclusions:

1. Wi-Fi Direct Peer discovery works pretty well
2. Wi-Fi Direct Service discovery doesn't work very well at all

We ran into endless problem with Wi-Fi Direct Service discovery including but not limited to:
* Phones from different manufacturers were highly likely to either never find each other over Wi-Fi Direct Service Discovery or if they did find each other it could take many minutes
* The Wi-Fi Direct Service Discovery stack had a habit of just stopping to work after some period of time. And once it stopped working the only way to get it working against was to reboot the phone.
* We encountered random disruptions in the working of the main Wi-Fi stack when we used Wi-Fi Direct Service discovery for any extended period of time.

So while Wi-Fi Direct Service discover was perfect for our needs in theory, in practice it wasn't going to work.

Now we could have fallen back to Wi-Fi Direct Peer Discovery. But this wasn't a good solution either because the instability we saw in the Wi-Fi stack appeared to also apply to Wi-Fi Direct Peer Discovery. Also Wi-Fi Direct Peer Discovery made ad-hoc connections impossible. For example,