Original Link: http://www.anandtech.com/show/6745/nexus-4-jdq39-422-ota-update-removes-unofficial-lte-on-band-4
Nexus 4 JDQ39 4.2.2 OTA Update Removes Unofficial LTE on Band 4by Brian Klug on February 13, 2013 9:15 PM EST
Just after it launched, we discussed how the Nexus 4 included undocumented support for LTE on Band 4 (AWS) which could be enabled simply by choosing the appropriate RAT (Radio Access Technology) under Phone Info (by dialing *#*#4636#*#* - INFO). Back then, I noted that it was highly unlikely this would stick around for very long without the proper FCC paperwork, and although it took a bit longer than I expected, today's 4.2.2 update does away with this unofficial support for LTE entirely.
The OTA update for the Nexus 4 includes both software changes to Android (4.2.2 build JDQ39) along with a new baseband software image in the form of a delta update (radio.img.p). I tested the Nexus 4 the same way as I did in the previous article, on an Anritsu MD8475A base station emulator, which enables me to test any configuration or band network, and setup a Band 4 LTE network to attach the Nexus 4 to.
Before the OTA update, with the appropriate "LTE Only" selection made in the aforementioned "Phone Info" menu for preferred network type, the Nexus 4 would quickly attach to Band 4 LTE. After applying the update, the handset no longer attaches at all. In addition, trying to select the "LTE Only" preferred network type now quickly changes back to "WCDMA Preferred," likewise choosing one of the other modes which include LTE results in a change back to "WCDMA Preferred" after exiting and coming back. Previously this setting would persist until a reboot took place.
I'm not surprised that undocumented LTE on Band 4 was removed, I am surprised however that it took this long. This also settles any lingering questions about LG Electronics filing for a Class II permissive change for the Nexus 4 to enable LTE on the bands supported by the hardware. If having support for LTE on Band 4 on your Nexus 4 is important to you, I'd recommend holding off on updating with the OTA zip for now, no doubt people will also make their own update images without the radio update as well.
The Android 4.2.2 update includes a number of other small changes as noted by other users, including enhanced quick toggles that can be long pressed to toggle WiFi or Bluetooth.
Source: Google (OTA .zip link)