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diff --git a/doc/manuals/chapters/overview.adoc b/doc/manuals/chapters/overview.adoc new file mode 100644 index 0000000..785e26b --- /dev/null +++ b/doc/manuals/chapters/overview.adoc @@ -0,0 +1,62 @@ +[[chapter_introduction]] +== Overview + +[[intro_overview]] +=== About OsmoTRX + +OsmoTRX is a C/C++ language implementation of the GSM radio modem, +originally developed as the 'Transceiver' part of OpenBTS. This radio +modem offers an interface based on top of UDP streams. + + +The OsmoBTS bts_model code for OsmoTRX is called +`osmo-bts-trx`. It implements the UDP stream interface of +OsmoTRX, so both parts can be used together to implement a complete GSM +BTS based on general-purpose computing SDR. + +As OsmoTRX is general-purpose software running on top of Linux, it is +thus not tied to any specific physical hardware. At the time of this +writing, OsmoTRX supports a variety of Lime Microsystems and Ettus USRP SDRs via +the UHD driver, as well as the Fairwaves UmTRX and derived products. + +OsmoTRX is not a complete GSM PHY but 'just' the radio modem. This +means that all of the Layer 1 functionality such as scheduling, +convolutional coding, etc. is actually also implemented inside OsmoBTS. +OsmoTRX is a software-defined radio transceiver that implements the Layer 1 +physical layer of a BTS comprising the following 3GPP specifications: + +* TS 05.01 "Physical layer on the radio path" +* TS 05.02 "Multiplexing and Multiple Access on the Radio Path" +* TS 05.04 "Modulation" +* TS 05.10 "Radio subsystem synchronization + +As such, the boundary between OsmoTRX and `osmo-bts-trx` is at +a much lower interface, which is an internal interface of other more +traditional GSM PHY implementations. + +Besides OsmoTRX, there are also other implementations (both Free +Software and proprietary) that implement the same UDP stream based radio +modem interface. + +[[fig-gprs-pcubts]] +.GSM network architecture with OsmoTRX and OsmoBTS +[graphviz] +---- +digraph G { + rankdir=LR; + MS0 [label="MS"]; + MS1 [label="MS"]; + MS0->SDR[label="Um"]; + MS1->SDR [label="Um"]; + SDR -> OsmoTRX [label="Raw Samples"]; + OsmoTRX->BTS [label="bursts over UDP"]; + BTS->BSC [label="Abis"]; + BSC->MSC [label="A"]; + BTS->PCU [label="pcu_sock"]; + PCU->SGSN [label="Gb"]; + OsmoTRX [color=red]; +} +---- + +For more information see +https://osmocom.org/projects/osmotrx/wiki/OsmoTRX |