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CSD: typo fixes

This commit is contained in:
Harald Welte 2023-03-15 21:33:40 +01:00
parent 4d1f688ac0
commit 482726a6d9
2 changed files with 12 additions and 12 deletions
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2023/osmodevcall-gsm_csd/gsm_csd.pdf
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2023/osmodevcall-gsm_csd/gsm_csd.tex
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@ -167,7 +167,7 @@
\begin{itemize}
\item Dial-up access to BBSs, Databases, etc. (pre-internet days)
\item Dial-up access to other networks like X.25/Datex-P (gateways)
\item Dial-up access to Interenet or private IP networks (SLIP/PPP)
\item Dial-up access to Internet or private IP networks (SLIP/PPP)
\end{itemize}
\end{itemize}
}\hfill\parbox{.50\textwidth}{
@ -203,7 +203,7 @@
\end{frame}
\begin{frame}{CSD Services}
CSD comes im many different flavours:
CSD comes in many different flavours:
\begin{itemize}
\item both synchronous and asynchronous services
\item both transparent and non-transparent services
@ -215,7 +215,7 @@ CSD comes im many different flavours:
\begin{frame}{Background: Synchronous Interface}
\begin{itemize}
\item {\it synchronous} means that receiver and transmitter share a common clock
\item bits are then transmitted one synchronous with that clock, usually 1 bit per clock cycle
\item bits are then transmitted synchronous to that clock, usually 1 bit per clock cycle
\item synchronous interfaces do not need start/stop bits, so they have higher user data throughput at same bps
\item simple synchronous interfaces need separate wires for clock, in addition to data
\item example for other synchronous serial interfaces: SPI, I2C
@ -248,7 +248,7 @@ CSD comes im many different flavours:
\item works only for async services
\item characters sent via RLP (Radio Link Protocol)
\item control lines (RTS/CTS/DSR/DTR/DCD) serialized via L2RCOP (Layer 2 Character Oriented Protocol)
\item RLP is a HLDC-style protocol with ABM
\item RLP is a HDLC-style protocol with ABM
\item frames are re-transmitted as needed
\item indeterminate latency, but guaranteed delivery (or disconnect)
\item conceptual relation to ISDN V.120 or X.75
@ -287,7 +287,7 @@ CSD comes im many different flavours:
\begin{itemize}
\item Classic GSM uses TRAU frames over E1 timeslots/sub-slots
\item Special TRAU frame formats specifically for CSD
\item Modern GSM implementations don't have no (channelized) E1 anymore
\item Modern GSM implementations don't have (channelized) E1 anymore
\item various proprietary, vendor-specific formats instead of TRAU frames :/
\end{itemize}
\end{frame}
@ -309,8 +309,8 @@ CSD comes im many different flavours:
\begin{frame}{Interworking with ISDN data calls}
\begin{itemize}
\item The GSM MSC is just a fancy ISDN switch anyway
\item Call Control is using SS7/ISUP like other switches in ISDN; no difference between voice and daat
other than the indicatd service (voice vs. UDI/RDI)
\item Call Control is using SS7/ISUP like other switches in ISDN; no difference between voice and data
other than the indicated service (voice vs. UDI/RDI)
\item Transparent CSD is just a slightly modified V.110, so CSD-modified V.110 frames are mapped 1:1
to standard ISDN V.110 frames (happens in the TRAU; typically BSC-colocated)
\item Non-transparent CSD requires Inter-Working Function (IFW; typically MSC-colocated); IWF
@ -324,7 +324,7 @@ CSD comes im many different flavours:
transparent or non-transparent CSD call and implements an ITU V-Series Modem towards the POTS
\item This has been tested in some trials; not sure if any operator had deployed this
in production. Reason: Expensive modem banks with one modem per concurrent call required.
\item Update: I stand corrected - it was deployed in commercial networks both in the US and Germany
\end{itemize}
\end{frame}
@ -367,7 +367,7 @@ CSD comes im many different flavours:
}
\end{frame}
\begin{frame}{Omsocom CSD plans}
\begin{frame}{Osmocom CSD plans}
\begin{itemize}
\item support for 2400/4800/9600 bps CSD across CNI ({\tt osmo-bts/bsc/msc/mgw})
\begin{itemize}
@ -379,7 +379,7 @@ CSD comes im many different flavours:
\end{itemize}
\end{frame}
\begin{frame}{Omsocom CSD status}
\begin{frame}{Osmocom CSD status}
\begin{itemize}
\item convolutional [de]coder, [de]interleaving implemented
\begin{itemize}
@ -399,9 +399,9 @@ CSD comes im many different flavours:
\end{itemize}
\end{frame}
\begin{frame}{Omsocom CSD TODO}
\begin{frame}{Osmocom CSD TODO}
\begin{itemize}
\item Lots :)
\item Lots :) Check redmine issues with "CSD" tag.
\end{itemize}
\end{frame}