[Xiaomi Mi 5 Guides, News, & Discussion] pakidermo5000:
Have you seen this?

http://xdaforums.com/google-nexus-5/general/radio-enable-lte-band-3-nexus-5-d820-t2928561/page4

http://www.iqiyi.com/w_19rskk6w0x.html#vfrm=8-7-0-1

http://bbs.gfan.com/android-7656824-1-1.html

If I am not wrong, what he does is to take the original qcn. Then, take qcns from other phones with the same hardware and get the NV items that are needed to run the bands that are not included in the original qcn. He puts the instructions into xml files and "flashes" the instructions to the phone.

---------- Post added at 09:34 PM ---------- Previous post was at 08:43 PM ----------

I think we are getting there,

basically what the OP does is just change the configuration and it works if the bands are supported, but if the bands are not supported the phone does not know what to do.

We have to replicate these steps for Nexus 5. Important step is to get the right NVitem values

If you check what they did, they activate the lte-bc-config, but they also add other data, see the qcn file

<!-- QDART RF nv files by Azlun
-->
<NvSource>
<!-- Add and3,Band8,Band26,Band41 in LTE bands over D820
default 17104923 decially = binary:
00000000 00000000 00000000 00000000 00000001 00000101 00000000 00011011B
(band 25/19/17/ 5/4/ 2/1)
= 1099562287263 decially = binary:
00000000 00000000 00000001 00000000 00000011 00000101 00000000 10011111B
(band 41!/26!/25/19/17/8!/5/4/3!/2/1)
** other referenece,
ONLY Band12 = 17106971
ONLY Band3,26 = 50659359
-->
<NvItem id="6828" subscriptionid="0" name="NV_LTE_BC_CONFIG_I" mapping="direct" encoding="dec" index="0">1099562287263,0</NvItem>
<NvItem id="6829" subscriptionid="0" name="NV_LTE_BC_CONFIG_DIV_I" mapping="direct" encoding="dec" index="0">1099562287263,0</NvItem>

[COLOR="Red"][B]Upt to here is what the OP does, but there is still more needed !!!
see the code below for each extra band.[/B][/COLOR]

<!-- LTE_B3-->
<!--
<NvItem id="20278" subscriptionid="0" name="RFNV_LTE_B3_RX_GAIN_I" mapping="direct" encoding="dec" index="0">12,12,11,-5,-11,12,0,0,0,0,0,0,0,0,0,0</NvItem>
<NvItem id="20279" subscriptionid="0" name="RFNV_LTE_B3_RX_GAIN_VS_FREQ_I" mapping="direct" encoding="dec" index="0">11,2,4,4,2,0,-1,0,3,6,9,8,7,6,7,10,10,2,4,3,1,-1,-1,0,2,6,8,8,6,5,7,9,11,2,5,4,2,0,-1,0,3,7,9,9,7,6,8,10,10,2,4,4,1,0,-1,0,4,6,9,8,6,6,7,9,9,2,4,3,1,-1,-2,0,2,6,9,8,6,4,6,9,11,4,3,2,0,-1,-1,0,2,4,5,6,5,5,7,10,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0</NvItem>
<NvItem id="20309" subscriptionid="0" name="RFNV_LTE_B3_EXP_HDET_VS_AGC_I" mapping="direct" encoding="dec" index="0">1037,1056,1080,1124,1180,1252,1358,1501,1680,1930,2225,2611,3072,3650,4095,4095</NvItem>
<NvItem id="20310" subscriptionid="0" name="RFNV_LTE_B3_TX_LIMIT_VS_FREQ_I" mapping="direct" encoding="dec" index="0">4,4,2,1,0,-1,-1,-1,-1,0,0,1,1,0,0,-2</NvItem>
<NvItem id="20321" subscriptionid="0" name="RFNV_LTE_B3_C1_RX_GAIN_I" mapping="direct" encoding="dec" index="0">32,33,33,21,23,14,0,0,0,0,0,0,0,0,0,0</NvItem>
<NvItem id="20322" subscriptionid="0" name="RFNV_LTE_B3_C1_RX_GAIN_VS_FREQ_I" mapping="direct" encoding="dec" index="0">6,4,4,-3,0,6,7,0,-8,-13,-11,-6,-2,-1,-3,0,6,4,4,-3,0,6,7,0,-8,-13,-11,-6,-2,-1,-3,0,6,4,4,-3,0,7,7,0,-8,-13,-11,-5,-2,-1,-3,0,7,5,5,-2,2,7,6,0,-7,-10,-8,-3,-1,-1,-2,1,6,2,3,-3,-1,3,4,0,-6,-10,-10,-6,-3,-1,-2,1,7,2,2,-3,-2,2,4,0,-5,-9,-10,-6,-3,-1,-1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0</NvItem>
-->
<NvItem id="24228" subscriptionid="0" name="RFNV_LTE_B3_TX_MULTI_LIN_V3_DATA_I" mapping="byteStream" encoding="hex" index="0">00 00
[COLOR="red"][B][B] I have cut it, just too long[/B][/B][/COLOR]

[COLOR="Blue"][B]see here for all info[/B][/COLOR]
[url]http://xdaforums.com/google-nexus-5/general/radio-enable-lte-band-3-nexus-5-d820-t2928561[/url]

,</NvItem>
<!-- LTE_B26 no additional patch nv to add for D820-->
<!-- LTE_B41 no additional patch nv to add for D820 -->
</NvSource>