It wouldn't be an oversized iPhone without the phone parts—this end of the logic board sports all of the RF components.

Qualcomm M9615M LTE Processor with 1 Gb (128 MB) of DRAM

TriQuint TQF6514 RF Power Amplifier Module—similar to the 6414 in the iPhone 5s

Three Skyworks SKY77-series LTE RF Power Amplifier/Duplexer Modules

Two Avago A79-series LTE RF Power Amplifier/Duplexer Modules

227 LG—likely a Murata Antenna Switch/Filter Module

Qualcomm WTR1605L LTE/HSPA+/CDMA/EDGE/GPS Transceiver

Qualcomm PM8018 PMIC