Replicant

{{>toc}}

h1. Tasks that could be funded

h2. What kind of tasks to fund

/!\ This is a draft. It doesn't represent the Replicant project decisions yet.

h3. Funding strategies

* Fund important and urgent tasks?

* Fund tasks that no one want to work on?

h3. Applicant criteria

* The applicants will need to already have Patches in Replicant to apply. So if you want to apply and don't have any patches in Replicant, the easiest way is just to send some useful patches.

* The applicants will need to be able to demonstrate that they have the required skills by showing contributions in free and open source project in similar areas.

* The applicants will need to be able to do contract work

h3. Grant application template

*url*: https://nlnet.nl/propose/

*scope* : Is it per task?

h4. Contact information

|_. Email address | [[PrivateContact#Email]] + FSF |

|_. Phone numbers | GNUtoo's phone number + FSF's phone number |

|_. Organisation | Replicant and the FSF |

|_. Country | France(GNUtoo), USA (FSF) |

h4. General project information

|_. Project name |  <Depend on the task?>  |

|_. Website / wiki | https://replicant.us? https://redmine.replicant.us/projects/replicant/wiki/Tasks_v2 ? |

|_. Abstract: Can you explain the whole project and its expected outcome(s).in 1200 characters

Please be short and to the point in your answers; focus primarily on the what and how, not so much on the why.

Add longer descriptions as attachments (see below).

If English isn't your first language, don't worry - our reviewers don't care about spelling errors, only about great ideas.

On the up side, you can be as technical as you need to be (but you don't have to).

Do stay concrete. | <Depend on the task?> |

|_. Have you been involved with projects or organizations relevant to this project before?

And if so, can you tell us a bit about your contributions? | Yes: I've been involved in Replicant since the beginning both as a developer and for managing the project:

As a developer:

* I did most/all the initial system work and made it work for the the HTC Dream, and the Google Nexus One.

* I also worked on porting the Goldelico GTA04, Galaxy nexus, Galaxy Tab 2 7.1 along with other Replicant developers and did various bug fixes and improvements.

* I am also doing code reviews for patches.

For managing the project:

* public relations

* fund usage decisions

* infrastructure (sysadmin, etc)

* documentation

* project direction and strategic decisions |

h4. Requested support

|_. Requested Amount (Between 5000 and 50000 Euros) | |

|_. * Explain what the requested budget will be used for? | <depends on the task> |

|_. * Does the project have other funding sources, both past and present? | 

The Replicant project has about 200000 dollars at disposition:

* The Replicant project has a donation page https://crm.fsf.org/civicrm/contribute/transact?reset=1&id=19. Part of the donations were used for buying devices and reimburse conference attendances. We have about 20000 dollars remaining from the donation.

* The Replicant project recently received 200000 dollars from Handshake: https://www.fsf.org/news/free-software-foundation-receives-1-million-from-handshake As the FSF takes 10% that leaves us 180000 dollars |

|_. Compare your own project with existing or historical efforts. | <Depend on the task?> |

|_. What are significant technical challenges you expect to solve during the project, if any? | <Depend on the task?> |

Describe the ecosystem of the project, and how you will engage with relevant actors and promote the outcomes?

<pre>

The Replicant project contributors and the FSF will supervise

contractors to do the work.

I will write a blog post to anounce that the Replicant project

has got some funding for this specific task, and that it is

looking for a contractor to work on it. This is to make sure

that every one has equals chances in the application process.

Then the most suited contractor will be selected. Only contractors

that already have worked on similar tasks as part of free and open

source software projects will be chosen. This way we can look at

their existing contributions and make sure that they are able to

do the task before engaging with them.

Some people already involved in the Replicant project with proven

contributions, me included, are already interested about doing such

contract work, so finding someone suitable to work on the task

should not be an issue.

</pre>

|_. Attachments | None |

h4. How may we handle your information

|_. What should we do in the other case,

 e.g. when your project is not immediately selected? | I allow NLnet Foundation to keep the information I submit on record, should future funding opportunities arise |

|_. Send me a copy of this application. | check-box checked |

|_. PGP pubkey | None (if we use Replicant contact address, we can't encrypt to it) |

h3. Discussions

There is "a thread about funding on the mailing list":https://lists.osuosl.org/pipermail/replicant/2019-January/001774.html about that

h2. Tasks that could be funded

h3. Port Replicant to a newer Android version

Replicant is currently based on LineageOS 13 which is based on Android 6.0.

It is becoming very urgent to upgrade Replicant to a newer release of Android, as Android 6.0 is not supported anymore. It would probably also make it way easier to fix the following issues:

* Replicant is currently lagging behind with security fixes

* Replicant cannot be built from a GNU/Linux distribution that follows the Free Software Distribution Guidelines

*Hardware requirements* :

* A computer that is able to build Replicant.

* A smartphone or tablet that can easily supported by the new version of Replicant and that meet Android 9 [[HardwareRequirements]].

*Expected outcomes*:

* Remove all proprietary components of LineageOS and make sure that Replicant follows the "Free Software Distributions Guidelines (FSDG)":https://www.gnu.org/distros/"

* Port all the changes needed to successfully boot without any proprietary software in Replicant

* Make sure that most of the security issues are fixed, and lower the attack surface if possible.

* Make sure that Replicant can be built on a GNU/Linux distribution that follows the "Free Software Distributions Guidelines (FSDG)":https://www.gnu.org/distros/

* Rebrand LineageOS as Replicant

*Funding*: We could apply to https://nlnet.nl/PET

h4. Subtasks

The following sub-tasks could also be worked on along with porting Replicant to a newer Android version, as it doesn't make sense to do them for older Replicant versions:

* [[Tasks v2#Add support for devices with an upstream Linux kernel|Add support for devices with an upstream Linux kernel]]

* [[Tasks v2#Add support for more recent smartphones|Add support for more recent smartphones]]

* [[Tasks v2#Add support for the devices supported in Replicant 6.0 and 4.2|Add support for the devices supported in Replicant 6.0 and 4.2]]

* [[Tasks v2#Support in-system upgrades|Support in-system upgrades]]

h4. Add support for devices with an upstream Linux kernel

It would also be useful to support devices using kernels that are based on upstream Linux with the least amount of kernel changes possible:

Currently, Replicant uses a dedicated Hardware Abstraction Layer per device, because device manufacturers implemented non-standard kernel interfaces. However, Android works with mainline kernels and supports plug-n-play hardware nowadays, so it makes sense to have generic Hardware Abstraction Layers for the standard interfaces of the Linux kernel (ALSA, V4L2, etc).

See also the [[Upstream#Upstream-Linux|wiki page on Upstream Linux]] for more details on why using upstream kernel is beneficial, and for what devices to choose to work on this task.

*Hardware requirements* :

In addition to the requirements for porting Replicant to a newer Android version:

* A device that is already well supported by the Upstream kernel. That device don't need to be already supported by LineageOS or even Android.

*Difficulty*: Medium

*Requirements/Prerequisites*: Knowledge of C, some C++, the ability to understand Java, kernel interfaces knowledge

*Expected outcomes*: 

* Basic features working (graphics, touchscreen, buttons, audio, and telephony if there is a modem) for at least one device that use a kernel that is very closely based on upstream Linux with the generic HALs.

h4. Add support for more recent smartphones

The most recent smartphones that Replicant support are quite old (they were made around 2013). The goal here is to add support for more recent smartphones in Replicant.

Even if we think that it's at lot more important to support devices that are better for freedom (samsung devices usually have a nonfree bootloaders), adding supporting common (Samsung) phones and tablets is relatively easy and fast to do and could be a good way to get started in contributing to Replicant. 

It's advised to pick a device that:

* has an isolated modem (no shared memory between the modem and the processor running Android)

* meets Android 9 [[HardwareRequirements]] to still be useful when Replicant will be ported to Android 9

* has a modem that can easily be supported by samsung-ril and libsamsung-ipc 

* is or will be supported by lineageOS

Make sure to evaluate the device before starting to work on it. Some devices have been evaluated in the [[TargetsEvaluation|TargetsEvaluation wiki page]]. There is also a "forum section":https://redmine.replicant.us/projects/replicant/boards/27 for devices evaluation.

*Hardware requirements*:

In addition to the requirements for porting Replicant to a newer Android version: 

* One or more smartphones that are already well supported by LineageOS or the AOSP project and that can easily be added in Replicant.

*Difficulty*: Medium

*Expected outcomes*: 

* Basic features working (graphics, touchscreen, buttons, audio, and telephony if there is a modem) without requiring Replicant or the user to install or ship nonfree software or firmwares.

h4. Add support for the devices supported in Replicant 6.0 and 4.2

When porting Replicant to a new version, it's also a good idea to keep supporting all the devices we supported in the older versions, however this is not always possible or desirable.

In order not to require too much work, devices that were previously supported will have to meet the [[HardwareRequirements]] of the new Android version. Here many of the devices already supported by Replicant 6.0 already meet such requirements.

*Hardware requirements and dependencies*:

In addition to the requirements for porting Replicant to a newer Android version:

* The port to the new Android version needs to be complete for at least one device before starting to work on this.

* All the devices will need to be shipped to (or acquired by) the person working on this task before starting to work on this.

*Expected outcomes*: 

* For each device: evaluate if they meet the hardware requirements of the new Android version and document that in the wiki in an appropriate location  ( like [[HardwareRequirements]] for instance)

* For each device: basic features working (graphics, touchscreen, buttons, audio, and telephony if there is a modem) without requiring Replicant or the user to install or ship nonfree software or firmwares.

*Difficulty*: Medium

h4. Support in-system upgrades

It would be useful for a Replicant device to be able to update itself to a new version of Replicant without requiring being connected to a PC. LineageOS already supports this; we suspect that it should be possible to adapt this LineageOS functionality to Replicant.

Whenever possible, it would be useful to complete and submit some of the code written for Replicant to LineageOS.

*Difficulty*: Medium

*Expected outcomes*: 

* In-system updates working without being connected to a PC

h4. nlnet Grant application

|_. Project name | Port Replicant to a newer Android version |

|_. Website / wiki | https://redmine.replicant.us/projects/replicant/wiki/Tasks_funding#Port-Replicant-to-a-newer-Android-version |

Abstract: Can you explain the whole project and its expected outcome(s).in 1200 characters

<pre>

Replicant is a fully free software Android distribution which

is approved by the FSF (http://gnu.org/distros).

The combination of Android Open Source Project source code with

the Linux source code provided by the device vendor is not

sufficient to produce a fully free Android distribution that

works: A lot of the code that makes critical hardware component

work (the modem, graphics, audio, gps, etc) is in userspace.

Because of that most device manufacutrers don't release them as

free software.

To make such hardware work, the Replicant project manages to

replace or avoid such nonfree software.

Replicant is currently based on LineageOS 13.0 which in turn is based

on Android 6.0.1 which are both not supported anymore. Replicant is

based on LineageOS because it supports many more smartphones and

tablets than the Android Open Source Project.

The project consists in porting Replicant changes on top of the

"Android 9" release of the Android Open Source project,

and when LineageOS 16 will be ready, to backport our changes on

top of LineageOS 16.

</pre> 

|_. Have you been involved with projects or organizations relevant to this project before?

And if so, can you tell us a bit about your contributions? | SEE TEMPLATE |

|_. Requested Amount (Between 5000 and 50000 Euros) | 50000 Euros |

|_. Does the project have other funding sources, both past and present? | SEE TEMPLATE |

Explain what the requested budget will be used for? 

<pre>

The budget will only be used to fund this task through contract work.

However it is difficult to evaluate precisely the amount of time such work

will take as sometime bugs can slow down a lot that kind of work.

For instance, when adding support for the Galaxy Nexus to Replicant,

a lot of time was spent dealing with display issues that didn't affect

the upstream projects, because they relied on the GPU which required

nonfree software to work.

We think it will take something between 2 and 6 month of work

for one full time developer.

When that work is done, we will then need to add support for most the

smartphones we currently support in Replicant, add support for more

recent smartphones as the most recent one we currently support has

been released in 2013.

We also need to enable Replicant to use upstream Linux kernels in order

to support devices with free software bootloaders like the NC_1 from

Necuno Solutions, and to lower the time required to maintain Replicant.

If the additional tasks like adding support for devices using an upstream Linux

kernel is not done when this funding has run out, the Replicant project will

most probably continue funding contract work in order to make sure that the work

is completed.

</pre>

|_. Compare your own project with existing or historical efforts. | TODO |

What are significant technical challenges you expect to solve during the project, if any?

<pre>

To upgrade Replicant to a new Android release, we need to

adapt our free software replacement, and to find ways to not

depend on the nonfree software that we didn't replace

yet (like GPU drivers). We for instance had to find ways to

make Replicant graphics fast enough without being able to use

the GPU, as there is no free software GPU driver for some of

the devices we support.

Android has also changed a lot since Android 6.0.1: It has been

re-architectured to provide a more stable interface for userspace 

hardware support code.

</pre>

|_. Describe the ecosystem of the project, and how you will engage with relevant actors and promote the outcomes? | SEE TEMPLATE |

|_. Attachments | SEE TEMPLATE |

h3. Implement the missing features of Samsung-RIL

Samsung-RIL is the RIL (Radio Interface Layer) that many Replicant devices use to communicate with the modem.  It is a free, reverse-engineered replacement for the proprietary RIL that the Samsung phones ship with by default (which has been found to have backdoors).

Right now, Samsung-RIL mostly implements only the protocol features that are absolutely necessary for the phone to be operable.  As a result, many more rarely used protocol features are unimplemented, which decreases functionality compared to the proprietary RIL. You can help by implementing the missing features of Samsung-RIL.

It would also be nice to fix most the reported bugs involving samsung-ril and libsamsung-ipc that are impacting users very seriously. This includes the bugs about the SIM card not being detected, and the issue about having metallic sound quality when doing voice calls over 3G (bug #1773). It would also be nice to be able to recover from EFS (the modem filesystem) corruptions (Bug #1869).

*Hardware requirements* : A computer that is able to build Replicant. A smartphone or tablet supported by Samsung-RIL.

*Difficulty*: Medium to Hard

*Requirements/Prerequisites*: Knowledge of C.

*Expected outcomes*: Implement the missing features listed at [[Samsung-RIL]]. When all the features have been implemented, also ask usptream (LineageOS) if they want to use libsamsung-ipc and samsung-ril.

*Dependencies*: This task should be fairly independent as:

* [[Libsamsung-ipc]] should already be independent of the Android version (it can even run on GNU/Linux)

* [[Samsung-RIL]] can probably easily be adapted to newer Android version

*Funding*: We could apply to https://nlnet.nl/PET

h3. Implement a fully-featured QMI-RIL

The LTE variants of the Samsung Galaxy S3 and Samsung Galaxy Note 2 use a different modem from the non-LTE variants that Replicant currently supports.  You can help Replicant support those modems by implementing a QMI-RIL, which performs a similar role on the LTE variants as what Samsung-RIL performs on the currently-supported non-LTE variants.  Wolfgang has done some preliminary work on this, so you'll probably be picking up where he left off.

*Hardware requirements* : A computer that is able to build Replicant. A smartphone or tablet supported by QMI-RIL like the Galaxy SIII 4G (i9305).

*Difficulty*: Hard

*Requirements/Prerequisites*: Knowledge of C.

*Expected outcomes*: A QMI-RIL that supports voice calls, SMS, and data, with as complete a protocol implementation as possible.

*Dependencies*: This task should be fairly independent as:

* The lower layers should already be independent of the Android version as they are used under GNU/Linux

* [[QMI-RIL]] can probably easily be adapted to newer Android version

*Funding*: We could apply to https://nlnet.nl/PET

h3. Finish to port the Galaxy S 2 (I9100), Galaxy S 3 (I9300) and Galaxy Note 2 (N7100) to Mainline Linux

The the Galaxy S 2 (I9100), Galaxy S 3 (I9300) and Galaxy Note 2 (N7100) currently use a kernel based on a vendor fork of Linux, which poses a maintainability and security issue.  Forkbomb has done some initial work on porting these devices to use mainline Linux.  You can help by continuing this work. This would also enable these devices to use generic hardware abstraction layers (HAL) when abstractions layers are ready, and to do some research on whether the "TrustZone operating system":https://blog.fossencdi.org/u-boot-galaxys3.html can be removed from such devices.

*Hardware requirements* : A computer that is able to build Replicant. A Galaxy S 2 (I9100), Galaxy S 3 (I9300) or Galaxy Note 2 (N7100), and a serial port adapter to get the kernel boot logs.

*Difficulty*: Medium

*Requirements/Prerequisites*: C programming language, driver development

*Expected outcomes*: Audio working, modem working, and Replicant or LineageOS booting with mainline Linux.

h3. llvmpipe optimizations

Replicant was relying on Android's OpenGL library (libAGL) which is fast but very incomplete. This prevent running many f-droid applications like browsers and also create many other issues (#705).

"llvmpipe has been integrated in Replicant":https://git.replicant.us/replicant/external_mesa3d/log/ but it's not activated by default yet as it is very slow. It is also not fully complete.

To fix that, llvmpipe and/or the integration of it in Replicant should be obtimized, while still being able to run most of the applications that come from f-droid. llvmpipe and/or Mesa could be "configured not to implement very expensive OpenGL operations":https://www.mesa3d.org/perf.html. If that's not sufficent or if that breaks application compatibility, various software or hardware features (ARM NEON, hardware 2D acceleration, etc) could be used to improve the speed.

See also the [[GraphicsResearch#llvmpipe|wiki page about graphics research / llvmpipe]] and [[Graphics]] for more details about the issue. Other solutions fixing the problem might be acceptable too, if it makes more sense.

*Hardware requirements* : A computer that is able to build Replicant. A smartphone or tablet that is supported by Replicant to be able to test the result.

*Difficulty*: Medium / Hard (depending on the amount of obtmisations required)

*Requirements/Prerequisites*: See with the MESA project

*Expected outcomes*:

* Working EGL implementation

* fast enough graphics

* F-droid applications not crashing anymore because of EGL.

*Funding*: We could apply to https://nlnet.nl/PET

h4. Integrate llvmpipe with Gralloc / hwcomposer 

h1. Other tasks

h2. Tasks that are being defined

h3. Test infrastructure

Having an automated build and test infrastructure would be very beneficial for Replicant.

Issues:

* Running costs of such infrastructure have to be kept low, not to depend on continuous flow of money

h3. Documentation

A lot of time is spent on the wiki documentation, and a lot of information is redundant (for instance the installation guide)

TODO:

* Research documentation systems

* Research the technical knowledge required to use them

* Look into communities like RockBox on the benefit of non-wiki documentation

* Look if transitioning to non-wiki documentation would make the Replicant Project loose its contributors to the documentation

h2. Devices with 512M of RAM or less

We might want to consider Android 9 [[HardwareRequirements]] before working on that

h3. Advance the Optimus Black U-Boot and Linux mainline ports

The Optimus Black from LG is an interesting device from the perspective of freedom and privacy/security. It has the ability to run a free bootloader and uses an OMAP3 SoC that is well-documented and supported in upstream U-Boot (bootloader) and Linux (kernel). Its modem is well-isolated from the rest of the device, ensuring a sane base for privacy/security. Currently, the device-specific parts of the mainline U-Boot and Linux ports are still at an early stage, where they are functional with a very limited set of supported hardware.

Advancing the Optimus Black U-Boot and Linux mainline ports would allow using the device with free, up-to-date and maintainable software and would pave the way for support in GNU/Linux systems as well as Replicant. A list of priorities in hardware support will be defined, with the objective of tackling as many as possible.

*Hardware requirements* : A computer that is able to build Replicant. An Optimus Black with u-boot and modified boot pins, a serial port adapter to get the kernel boot logs.

*Difficulty*: Medium to Hard

*Requirements/Prerequisites*: C programming language, driver development

*Expected outcomes*: Improved hardware support for the Optimus Black in U-Boot and Linux

h3. Advance the Kindle Fire (first generation) U-Boot and Linux mainline ports

The Kindle Fire (first generation) from Amazon is an interesting device from the perspective of freedom and privacy/security. It has the ability to run a free bootloader and uses an OMAP4 SoC that is well-documented and supported in upstream U-Boot (bootloader) and Linux (kernel). It does not embed a modem, ensuring a sane base for privacy/security. Currently, the device-specific parts of the mainline U-Boot and Linux ports are still at an early stage, where they are functional with a very limited set of supported hardware.

Advancing the Kindle Fire (first generation) U-Boot and Linux mainline ports would allow using the device with free, up-to-date and maintainable software and would pave the way for support in GNU/Linux systems as well as Replicant. A list of priorities in hardware support will be defined, with the objective of tackling as many as possible.

*Hardware requirements* : A computer that is able to build Replicant. A Kindle Fire first generation, a serial port adapter to get the kernel boot logs.

*Difficulty*: Medium

*Requirements/Prerequisites*: C programming language, driver development

*Expected outcomes*: Improved hardware support for the Kindle Fire (first generation) in U-Boot and Linux

h3. Select and/or port a tablet with an Allwinner SOC to mainline Linux and U-boot, and Replicant

Tablets with Allwinner SOCs are an interesting targets because they do not use signed bootloaders and the SOCs and various devices using them have good Linux and u-boot mainline support. If not much work is required for that, once the code is merged, the candidate is also required to work on the generic abstraction layer project which is also documented in this page.

The chosen tablet should have:

* A SOC that has good mainline support, see "the Linux mainlining effort page on linux-sunxi":https://linux-sunxi.org/Linux_mainlining_effort for more details.

* A Free software bootloader, or the ability to easily add support for the tablet to a free software bootloader.

* The ability to power and use an USB WiFi card or chip that is compatible with the ath9k_htc driver.

It would be better if the chosen tablet doesn't use an AllWinner SOC with a PowerVR GPU, as MALI GPU have more probability to be usable with free software in the future.

*Hardware requirements* : A computer that is able to build Replicant. An Allwinner tablet, a serial port adapter to get the kernel boot logs.

*Difficulty*: Medium

*Requirements/Prerequisites*: C programming language, driver development

*Expected outcomes*: Replicant support for a tablet using an Allwinner SOC, with free software bootloader and mainline based Linux kernel.

h2. Tasks for Replicant 6.0

h3. Tackle security issues in Replicant 6.0

Replicant is plagued by various security issues, that are mostly due to using a downstream codebase. One of the most crucial issues is that Replicant uses an old version of the Android WebView (from circa 2015), which is also a functionality drawback.

An initial evaluation of the security issues in Replicant should be conducted, followed by the integration or update of the concerned components of the system.

It would also be nice to do the same for privacy issues. Since Replicant indirectly depends on the "Android Open Source Project" and directly depends on LineageOS, not all privacy issues might have been found fixed by Replicant. Once security issues have been fixed, it would be nice to try to identify as many privacy issues as possible, and in a second time to fix them.

*Hardware requirements* : A computer that is able to build Replicant. A smartphone or tablet that is supported by Replicant to be able to test the result.

*Difficulty*: Medium-Hard

*Requirements/Prerequisites*: Android build system, knowledge of system security, advanced git

*Expected outcomes*: Integration or update of components of Replicant to tackle security issues

h3. Fix the Free software distribution guidelines issues and improve the build system in Replicant 6.0

Replicant has some issues with "FSDG (Free System Distribution Guidelines)":https://www.gnu.org/distros/free-system-distribution-guidelines.html compliance: "F-droid":https://f-droid.org/ repository is not FSDG compliant anymore (Bug #1629), and Replicant can't be built from an FSDG distribution (Bug #1861). This ought to be fixed. Replicant should also be fixed to build without issue.

It would also be nice to have the build system not depend on pre-built dependencies anymore, and to document which FSDG compliant F-droid applications crash because Replicant's incomplete EGL implementation (#705) and tag such applications as incompatible (so they are greyed out) until the EGL implemetation is fixed. Ideally Replicant builds should also be made "reproducible":https://en.wikipedia.org/wiki/Deterministic_compilation if they are not already.

*Hardware requirements* : A computer that is able to build Replicant. A smartphone or tablet that is supported by Replicant to be able to test the result.

*Difficulty*: Easy

*Requirements/Prerequisites*: Knowledge of shell scripts and the ability to learn the Android build system

*Expected outcomes*: The ability to compile Replicant from "an FSDG distribution":https://www.gnu.org/distros/free-distros.html, F-droid only showing FSDG compliant software.

h2. Research

h3. Improve support for the free software compatible external WiFi adapter

All devices currently supported by Replicant have WiFi chips that requires a non-free firmware to work. So to have WiFi working with free software, users need to use external WiFi adapters. They typically use tiny ath9k_htc compatible USB WiFi adapter along with a tiny USB OTG Host adapter.

Such external USB WiFi adapters used with Replicant are originally intended for laptops, not phones. As a result, they tend to consume a lot of power. According to lsusb some ath9k_htc compatible devices can consume up to 500mA.

This poses several issues:

* Some smartphones and tablets might not be compatible, at the hardware level, with such big power consumption.

* They can adversely impact battery life

Such USB WiFi adapters can also randomly stop working completely on some devices (e.g. needing to unplug and replug the adapter periodically to keep it operational).

You will need to investigate reliability issues such as the one mentioned above and look how power consumption can be improved in the adapter firmware and/or kernel driver.

You will also need to investigate how much miliampers USB devices can use, at the hardware level, on the smartphones and tablets Replicant supports.

*Hardware requirements* : An ath9k_htc compatible WiFi card, the ability to measure the current usage, the ability to build the ath9k_htc firmware and driver.

*Difficulty*: Medium/Hard

*Requirements/Prerequisites*: Knowledge of C

*Expected outcomes*: Reliable WiFi with external WiFi adapter