[Trophy Windows Phone 7 Development] TheXev:
The following applies only to SparkW (HTC Trophy on Verizon Wireless)!!

GSM/Euro Spark users can ignore doing this to their own phones!

In my quest to figure out why my damn phone stayed stuck in 1X mode while tethering, I may have found a solution to keep the speeds faster (which is important to me, since my tethering is my primary internet connection).

This is also part of my quest to build/find a wireless driver that gets rid of the "random" wi-fi mac address issue while still maintaining Internet Sharing.

It has to do with the OEM package HTC_8x50_OS_WIRELESS. This is the Wi-fi driver, but it may also be a driver for the radio interface of the phone.

The differences between this file on Spark_W, and Spark GSM are minimal at best. Spark GSM adds the policy to enable the wi-fi hotspot (mxipupdate_hotspotconfig_01.provxml), meanwhile the Verizon driver has mxipcold_Wireless_Spark_W.provxml and BCM4329B1_002.002.023.0589.0608.hcd.

The package ID is the same for both GSM Spark and Spark_W, {A2A5F44F-FE02-496e-8926-6EDDC8CF9B44}.. and in my cooking experience, you can straight use the GSM driver on Spark_W with no adverse effects that I can notice.. and in my custom cooked rom, I noticed that my tethering download speeds seemed much MUCH faster using the GSM driver!

So.. I wanted to figure out WHY that is.

The .rgu file between the Spark GSM and Spark_W are IDENTICAL. There are no differences what so ever! So I got to looking at what mxipcold_Wireless_Spark_W.provxml does.

<characteristic type="HKLM\Software\Widcomm\BtConfig\Platform\RadioInit">
<parm name="BRCMConfigFile" value="\Windows\BCM4329B1_002.002.023.0589.0608.hcd" datatype="string" />

Looking at this string, this seems to assign some kind of file that may have to do with radio initialization.

This overrides the default value set by the rgu, which is:

[HKEY_LOCAL_MACHINE\Software\Widcomm\BtConfig\Platform\RadioInit]
"BRCMConfigFile"="\\Windows\\BCM4329B1_002.002.023.0436.0438.hcd"

And when using the GSM Spark driver, BCM4329B1_002.002.023.0436.0438.hcd is used and tethering speed improves!

Here comes the fun part! If you want to try this faster tethering, there is no need to flash an entire rom, you simply need to open up the registry editor, navigate to HKLM\Software\Widcomm\BtConfig\Platform\RadioInit , and change the value BRCMConfigFile to BCM4329B1_002.002.023.0436.0438.hcd (setting it to BCM4329B1_002.002.023.0589.0608.hcd will change it back)! After that, save the value, reboot the phone, and va-la, tethering speed has improved!

I haven't tested this tweak with good reception to see if I can get past the "350KB/s" cap I keep hitting with tethering in great reception areas (I have pulled 900kb/s on those same spots using my mothers Galaxy Tab 7.1), so I'm not sure if this is the "secret" to unlocking this artificial speed lock or not.. but I doubt it can hurt. I've been running this for about a month, and its not like Verizon has yet to detect my tethering yet.. so... I'd like for people to run Speakeasy Speedtest both before and after trying this registry tweak, to see if anyone else is getting a huge speed bump.

In my fringe reception area, I am going from 15KB/s on 1X to 50-80KB/s on 3G!

I don't believe this should have an adverse effect on battery life when NOT using Internet Sharing, but if you're on battery while using this, the 3G speeds may suck more juice out of your battery.

I'm always charging while tethering, so this tweak really works well for me! I hope others can test this and give me feedback to see if this really helps in higher reception areas. I live out in a very rural area with low cellular usage, so anything to get faster speed is golden!

*note* For anyone wondering, I haven't downloaded any new OEM/Spark drivers/roms to try and extract their wireless driver yet to try and fix the mac address issue... I can't simply take the newest Verizon driver and add the hotspot policy in, as IS won't start. :/