Subsystem (Msm77); Arm Microprocessor Subsystem; Gsm Subsystem - LG -P350 Service Manual

3.9 Subsystem (MSM7227)

3.9.1. ARM Microprocessor Subsystem

The MSM7227 device uses an embedded ARM1136JF-S, ARM926EJ-S microprocessor. This microprocessor,
through the system software, controls most of the functionality for the MSM, including control of the
external peripherals such as the keypad, LCD, SDRAM, and NANDFlash devices. Through a QUALCOMM
proprietary single-wire SBI (SSBI) the ARM926EJ-S configures and controls the functionality of the RTR6285
and PM7540 devices.
3.9.2. WCDMA Subsystem
The WCDMA subsystem performs the data conversions and signal processing necessary to maintain the
WCDMA air interface between the handset and the base station (and also the WCDMA network). The
subsystem components include:
-Searcher engine
-Demodulating fingers
-Combining block
-Frame deinterleaver
-Viterbi decoder
-Reverse link subsystem
-Turbo decoder
On the forward link traffic channel, the WCDMA subsystem searches, demodulates, and decodes incoming
pilot, sync, paging, and traffic channel information. It extracts low bit-rate packet data from the forward link
traffic channel and sends the packet data to the vocoder for processing. On the reverse link, the WCDMA
subsystem processes the packet data from the vocoder and modulates the reverse traffic channel.

3.9.3. GSM Subsystem

The GSM subsystem performs the data conversions and signal processing necessary to maintain the GSM air
interface, including PA gain control for GPRS support. For GSM, the power profile ramps up before the burst
and ramps down afterward. For GPRS, transmit bursts can occur in as many as four sequential slots and the
PA must be ramped up and down smoothly between each slot, holding the desired output power level
during each burst. GSM support includes:
-GSM release '99 (circuit switching)
-GPRS (packet switching)
-EDGE E2 power class for 8 PSK
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3. TECHNICAL BRIEF
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