OSMOCOMBB Software Implementation Stack overview

OSMOCOMBB software Implementation Stack Overview

Simply put, this article describes only the part of the software in which the GSM signal is received. No mention of the sending process, the boot loading/booting process, and various control paths, especially from layer1 to RF hardware.

First, the RF signal is received through the antenna and transmitted to the Rita mixer directly down-conversion to the I/Q baseband signal. The ADC is then passed to iota ABB's analog-to-digital converters. The final signal is passed to the baseband serial interface of the HARDWARECALYPSO DBB (Bsp:baseband serial port).

Within the HARDWARECALYPSO DBB, a digital baseband sample is passed from BSP to the DSP core, where processing, demodulation, interleaving, decoding, and so on, are passed to the ARM processor using a shared memory interface. On the ARM processor, the MAC block is processed using OSMOCOMBB's layer1 and sent to the UART via L1ctl.

On the PC side, the Osmocon program receives the L1CTL message on the serial interface and decomposes it into multiple different sercomm streams, passing l1ctl through the UNIX domain socket to any LAYER23 program that may be running (for example, mobile).

OSMOCOMBB Software Implementation Stack overview