initial checkin of slides for CCCB Datengarten
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\documentclass[11pt]{beamer}
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\usetheme{default}
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%\setbeamertemplate{frametitle}{}
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\newenvironment{myline}
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%{\usebeamerfont{frametitle}\usebeamercolor[fg]{frametitle}\vfill\centering}
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{\usebeamerfont{frametitle}\vfill\centering}
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{\par\vfill}
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\usepackage[pdf]{graphviz}
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\usetheme{Warsaw}
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\usecolortheme{whale}
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|
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\title{Cellular Base Station Technology}
|
||||
%\subtitle{Subtitle}
|
||||
\author{Harald~Welte}
|
||||
\date[September 2019, CCCB]{September 2019, CCCB Datengarten}
|
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\institute{osmocom.org / sysmocom.de}
|
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|
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|
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\begin{document}
|
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|
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\begin{frame}
|
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\titlepage
|
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\end{frame}
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|
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|
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\begin{frame}{Outline}
|
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\tableofcontents[hideallsubsections]
|
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\end{frame}
|
||||
|
||||
|
||||
\begin{frame}{About the speaker}
|
||||
\begin{itemize}
|
||||
\item Free Software + OSHW developer for more than 20 years
|
||||
\item Used to work on the Linux kernel from 1999-2009
|
||||
\item By coincidence among the first people enforcing the GNU GPL in court
|
||||
\item Since 2009 developing FOSS in cellular communications (Osmocom)
|
||||
\item Living and working in Berlin, Germany.
|
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\end{itemize}
|
||||
\end{frame}
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|
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\section{Introduction}
|
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|
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\begin{frame}{What is a Cellular Base station?}
|
||||
\begin{columns}
|
||||
\column{0.38\linewidth}
|
||||
\centering
|
||||
\includegraphics[width=50mm]{gsm-tower.jpg}
|
||||
\column{0.58\linewidth}
|
||||
\begin{itemize}
|
||||
\item transmits and receives signals from/to mobile phones
|
||||
\item converts wireless signals to wired signals
|
||||
\item sits between the {\em air interface} and {\em back-haul}
|
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\item is the most visible part of cellular networks
|
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\end{itemize}
|
||||
\end{columns}
|
||||
\end{frame}
|
||||
|
||||
\begin{frame}{The 3GPP Specification point-of-view: 2G}
|
||||
\includegraphics[width=100mm]{GSM_structures.png}
|
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|
||||
{\tiny Image credits: tsaitgaist via Wikipedia}
|
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\end{frame}
|
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|
||||
|
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\begin{frame}{The 3GPP Specification point-of-view: 3G}
|
||||
\includegraphics[width=100mm]{UMTS_structures.png}
|
||||
|
||||
{\tiny Image credits: tsaitgaist via Wikipedia}
|
||||
\end{frame}
|
||||
|
||||
\begin{frame}{The 3GPP Specification point-of-view}
|
||||
What do we learn from this?
|
||||
\begin{itemize}
|
||||
\pause
|
||||
\item The telecom world loves acronyms
|
||||
\pause
|
||||
\item Specifications deal with functional / logical network elements
|
||||
\item Cellular network contains lots of elements
|
||||
\item Today, we only want to look at real-world base stations
|
||||
\end{itemize}
|
||||
\end{frame}
|
||||
|
||||
\begin{frame}{Terminology across cellular generations}
|
||||
\begin{table}
|
||||
\begin{tabular}{c | c | c | c | c}
|
||||
Generation & Name & Base Station & Back-haul & Next element \\
|
||||
\hline \hline
|
||||
2G & GSM/GPRS & BTS & Abis & BSC \\
|
||||
3G & UMTS & NodeB & Iub & RNC \\
|
||||
4G & LTE & eNodeB & S1 & MME + SGW \\
|
||||
5G & NR & gNodeB & N2 + N3 & AMF + UPF
|
||||
\end{tabular}
|
||||
\end{table}
|
||||
\end{frame}
|
||||
|
||||
\begin{frame}{Site vs. Cell}
|
||||
\begin{description}
|
||||
\item[Site] A single tower and associated equipment
|
||||
\begin{itemize}
|
||||
\item could in theory be omnidirectional
|
||||
\item in reality almost always sectorized
|
||||
\item classic setup is three-sector site (120 degree per sector)
|
||||
\end{itemize}
|
||||
\item[Cell] A logical cell in one cellular network generation
|
||||
\begin{itemize}
|
||||
\item typically illuminated by one (set of) antenna
|
||||
\end{itemize}
|
||||
\end{description}
|
||||
|
||||
\begin{itemize}
|
||||
\item Result: Single site often has 9 cells
|
||||
\item three sectors for each of 2G, 3G and 4G
|
||||
\end{itemize}
|
||||
\end{frame}
|
||||
|
||||
\begin{frame}{Components of a cellular base station}
|
||||
\begin{itemize}
|
||||
\item Tower/Pole (civil engineering part)
|
||||
\item Antenna
|
||||
\item Coaxial Cable
|
||||
\item Actual Base Station Electronics
|
||||
\item Back-haul connection to the rest of the network
|
||||
\item Power Supply / Environment (Fans, AC, UPS, ...)
|
||||
\end{itemize}
|
||||
\end{frame}
|
||||
|
||||
|
||||
\begin{frame}{Simplified Rx/Tx chain}
|
||||
\begin{itemize}
|
||||
\item Simplified Receiver chain:
|
||||
\digraph[scale=0.30]{rxsimple}{
|
||||
rankdir=LR;
|
||||
Antenna -> Duplexer -> RF_Filter -> LNA -> Mixer -> BB_Filter -> ADC -> PHY -> L2_L3
|
||||
}
|
||||
\item Simplified Transmitter chain:
|
||||
\digraph[scale=0.30]{txsimple}{
|
||||
rankdir=RL;
|
||||
L2_L3 -> PHY -> DAC -> BB_Filter -> Mixer -> PA -> RF_Filter -> Duplexer -> Antenna;
|
||||
}
|
||||
\end{itemize}
|
||||
Reality is more complex in many cases (circulator, active predistortion, rx diversity, ...)
|
||||
\end{frame}
|
||||
|
||||
|
||||
\begin{frame}{Even more Simplified Rx/Tx chain}
|
||||
\begin{itemize}
|
||||
\item Simplified Receiver chain:
|
||||
\digraph[scale=0.40]{rxsimple2}{
|
||||
rankdir=LR;
|
||||
Antenna -> Mixer [label=RF];
|
||||
Mixer -> ADC [label="Analog Baseband"];
|
||||
ADC -> PHY [label="Digital Baseband"];
|
||||
PHY -> L2_L3 [label="Primitives"];
|
||||
}
|
||||
\item Simplified Transmitter chain:
|
||||
\digraph[scale=0.40]{txsimple2}{
|
||||
rankdir=RL;
|
||||
L2_L3 -> PHY [label="Primitives"];
|
||||
PHY -> DAC [label="Digital Baseband"];
|
||||
DAC -> Mixer [label="Analog Baseband"];
|
||||
Mixer -> Antenna [label="RF"];
|
||||
}
|
||||
\end{itemize}
|
||||
\end{frame}
|
||||
|
||||
\section{Evolution of Cell Sites}
|
||||
|
||||
\subsection{Classic Cell Sites}
|
||||
|
||||
\begin{frame}{Classic Cell Site (year 2000)}
|
||||
\begin{columns}
|
||||
\column{0.28\linewidth}
|
||||
\centering
|
||||
\includegraphics[width=36mm]{RBS2206.jpg}
|
||||
\column{0.70\linewidth}
|
||||
The traditional way of building cell sites:
|
||||
\begin{itemize}
|
||||
\item (multiple) large racks full of equipment
|
||||
\item installed in [air conditioned] shelters
|
||||
\item all active electronics on ground level
|
||||
\item long lines of coaxial cable up the tower
|
||||
\item only passive element (antenna) up tower
|
||||
\item half of transmitted power lost in cable
|
||||
\end{itemize}
|
||||
{\tiny Image: Timur V. Voronkov via Wikimedia Commons (CC-BY-SA)}
|
||||
\end{columns}
|
||||
\end{frame}
|
||||
|
||||
\begin{frame}{Slightly less Classic Cell Site}
|
||||
\begin{columns}
|
||||
\column{0.28\linewidth}
|
||||
\centering
|
||||
\includegraphics[width=36mm]{nokia_flexi.jpeg}
|
||||
\column{0.70\linewidth}
|
||||
The fist step of logical evolution:
|
||||
\begin{itemize}
|
||||
\item equipment becomes smaller (partial rack)
|
||||
\item no strict need for large shelter anymore
|
||||
\item all active electronics on ground level
|
||||
\item long lines of coaxial cable up the tower
|
||||
\item only passive element (antenna) up tower
|
||||
\item half of transmitted power lost in cable
|
||||
\end{itemize}
|
||||
Equipment gets smaller, less power hungry and dissipates less heat
|
||||
{\tiny Image: Peter Schmidt @33dBm}
|
||||
\end{columns}
|
||||
\end{frame}
|
||||
|
||||
\begin{frame}{Coaxial Cables...}
|
||||
Why don't we like long coaxial cables
|
||||
\begin{itemize}
|
||||
\item good cabling is 1/2" to 1" in diameter and costs a lot
|
||||
\item installation is more like plumbing than cabling
|
||||
\item looses lots of energy over length of tower; compensated by
|
||||
\begin{itemize}
|
||||
\item downlink: more PA; waste of energy; causs more heat dissipation
|
||||
\item uplink: tower-mounted amplifier (TMA)
|
||||
\end{itemize}
|
||||
\item higher frequencies have even more losses (and we went from 900 MHz to 1800 MHz to 2100 MHz to 2600 MHz)
|
||||
\item more bands mean more coaxial cables in parallel
|
||||
\end{itemize}
|
||||
\end{frame}
|
||||
|
||||
|
||||
\begin{frame}{Towards Remote Radio Heads}
|
||||
So why not do he logical thing and ...
|
||||
\begin{itemize}
|
||||
\pause
|
||||
\item Generate the RF closer to the antenna?
|
||||
\end{itemize}
|
||||
Answer:
|
||||
\begin{itemize}
|
||||
\item Requires much more compact radios
|
||||
\item Requires passive cooling
|
||||
\item Difficult installation (heavy)
|
||||
\item Environmental protection (sun, rain, temperature cycles)
|
||||
\item Hard to service / replace
|
||||
\end{itemize}
|
||||
\end{frame}
|
||||
|
||||
\subsection{(Remote) Radio Heads}
|
||||
|
||||
\begin{frame}{(Remote) Radio Heads}
|
||||
Solution: Instead of moving all equipment up the tower,
|
||||
\begin{itemize}
|
||||
\item Move only the Analog parts of the chain up
|
||||
\item Transport digital samples up/down the tower
|
||||
\item Base Station split in two parts:
|
||||
\begin{itemize}
|
||||
\item Baseband processing ({\em digital unit})
|
||||
\item Radio processing ({\em radio unit})
|
||||
\end{itemize}
|
||||
\end{itemize}
|
||||
\end{frame}
|
||||
|
||||
\begin{frame}{Base Station split with Radio Heads}
|
||||
\begin{itemize}
|
||||
\item Incredibly Simplified Receiver chain:
|
||||
\digraph[scale=0.30]{rxsimple2split}{
|
||||
rankdir=LR;
|
||||
Antenna -> Mixer [label=RF];
|
||||
subgraph cluster_0 {
|
||||
label="Radio Head";
|
||||
Mixer -> ADC [label="Analog Baseband"];
|
||||
}
|
||||
ADC -> PHY [label="Digital Baseband Samples"];
|
||||
subgraph cluster_1 {
|
||||
label="Baseband Unit";
|
||||
PHY -> L2_L3 [label="Primitives"];
|
||||
}
|
||||
}
|
||||
\item Incredibly Simplified Transmitter chain:
|
||||
\digraph[scale=0.30]{txsimple2split}{
|
||||
rankdir=RL;
|
||||
subgraph cluster_0 {
|
||||
label="Baseband Unit";
|
||||
L2_L3 -> PHY [label="Primitives"];
|
||||
}
|
||||
subgraph cluster_1 {
|
||||
label="Radio Head";
|
||||
PHY -> DAC [label="Digital Baseband Samples"];
|
||||
DAC -> Mixer [label="Analog Baseband"];
|
||||
}
|
||||
Mixer -> Antenna [label="RF"];
|
||||
}
|
||||
\end{itemize}
|
||||
\end{frame}
|
||||
|
||||
\begin{frame}{Cell Sites with (Remote) Radio Heads}
|
||||
\includegraphics[width=100mm]{antennas-and-rrus.jpg}
|
||||
\end{frame}
|
||||
|
||||
\begin{frame}{Cell Sites with (Remote) Radio Heads}
|
||||
\includegraphics[width=100mm]{cellular-tower-2172041_1920.jpg}
|
||||
\end{frame}
|
||||
|
||||
\begin{frame}{Cell Sites with (Remote) Radio Heads}
|
||||
\includegraphics[width=92mm]{lots-of-radioheads.jpeg}
|
||||
|
||||
{\tiny Image: Peter Schmidt @33dBm}
|
||||
\end{frame}
|
||||
|
||||
\begin{frame}{New term: front-haul}
|
||||
\begin{itemize}
|
||||
\item {\em back-haul} is the connection between cell and core
|
||||
\item {\em front-haul} is the newly-introduced term for the link between radio head and baseband unit
|
||||
\item physical medium
|
||||
\begin{itemize}
|
||||
\item typically fiber-optic
|
||||
\item copper only if radio next to baseband unit
|
||||
\end{itemize}
|
||||
\item physical layer
|
||||
\begin{itemize}
|
||||
\item OBSAI (Open Base Station Architecture Initiative)
|
||||
\begin{itemize}
|
||||
\item Started in 2002 by Hyundai, LG, Nokia, Samsung, ZTE
|
||||
\item Mostly obsolete now
|
||||
\end{itemize}
|
||||
\item CPRI (Common Public Radio Interface)
|
||||
\begin{itemize}
|
||||
\item Ericsson, Huawei, NEC, Alcatel-Lucent
|
||||
\item more adoption particularly in recent years
|
||||
\end{itemize}
|
||||
\item eCPRI showing up on the horizon
|
||||
\end{itemize}
|
||||
\end{itemize}
|
||||
\end{frame}
|
||||
|
||||
\begin{frame}{from fiber-based front-haul to C-RAN}
|
||||
As digital baseband samples are transmitted over fiber optics
|
||||
\begin{itemize}
|
||||
\item can cover distances way above height of the tower
|
||||
\item single-mode transceivers allow for dozens of kilometers
|
||||
\item allows for cell sites without any shelter or rack
|
||||
\item leads to some people proclaiming {\em cloud-RAN} or {\em centralized RAN}
|
||||
\begin{itemize}
|
||||
\item don't distribute baseband compute power in the field
|
||||
\item bring all your baseband samples into the cloud
|
||||
\item perform CPU-intensive baseband function in data center
|
||||
\end{itemize}
|
||||
\item bit rates are high. A single LTE 2x2 MIMO carrier at 20MHz needs 2Gbps CPRI bandwidth
|
||||
\begin{itemize}
|
||||
\item site with 3 sectors and multiple carriers exceeds 10Gbps
|
||||
\end{itemize}
|
||||
\item latency constraints are biggest limiting factor
|
||||
\end{itemize}
|
||||
\end{frame}
|
||||
|
||||
%%\section{Antennas}
|
||||
|
||||
\begin{frame}{Antennas}
|
||||
\begin{itemize}
|
||||
\item You learned some antenna basics
|
||||
\item You think about an omnidirectional dipole
|
||||
\item Almost no cellular base station antenna is like that
|
||||
\item Complexity of those antennas has grown significantly
|
||||
\end{itemize}
|
||||
\end{frame}
|
||||
|
||||
\begin{frame}{Vertical polarization vs. X-Pol}
|
||||
\begin{itemize}
|
||||
\item Nominally, cellular signals are emitted in vertical polarization
|
||||
\item Industry has moved to two radiators at +45 / -45 degrees polarization
|
||||
\item This apparently gives polarization gain, as signals reflected (by buildings) don't arrive in
|
||||
vertical polarization
|
||||
\item Isolation between radiators typically 20..30dB, allowing use cases like
|
||||
\begin{itemize}
|
||||
\item operating two transmitters without combiner
|
||||
\item operating Rx + Tx without duplexer
|
||||
\item diversity reception within one antenna (polarization diversity)
|
||||
\end{itemize}
|
||||
\end{itemize}
|
||||
\end{frame}
|
||||
|
||||
\begin{frame}{Single-Band vs. Multiple Bands}
|
||||
\begin{itemize}
|
||||
\item So you rolled out a GSM network in 900 MHz
|
||||
\begin{itemize}
|
||||
\item then added more GSM on 1800 MHz
|
||||
\item then added 3G on 2100 MHz, ...
|
||||
\end{itemize}
|
||||
\item Do you add one new set of three sector antennas per band?
|
||||
\begin{itemize}
|
||||
\item space and weight constraints on tower
|
||||
\item they may affect each others' radiation pattersn
|
||||
\end{itemize}
|
||||
\item Industry responds with multi-band antennas
|
||||
\end{itemize}
|
||||
\end{frame}
|
||||
|
||||
\begin{frame}{Electrical Tilt}
|
||||
\begin{itemize}
|
||||
\item For RF planning, you want to determine where your cell physically ends
|
||||
\item Tilting antennas downwards means RF signals emitted eventually will hit the ground
|
||||
\item Adjusting the network by climing up the tower and mechanically adjusting tilt is cumbersome
|
||||
\item Industry responds with {\em Electrical Tilt}
|
||||
\item Rods are controlled by motors leading to {\em Remote Electrical Tilt (RET)}
|
||||
\end{itemize}
|
||||
\end{frame}
|
||||
|
||||
\begin{frame}{MIMO}
|
||||
\begin{itemize}
|
||||
\item MIMO means Multiple-In / Multiple-Out
|
||||
\item uses spatial diversity to establish multiple signals between different antennas
|
||||
\item 2x2 MIMO is standard with LTE today
|
||||
\item 5G / New Radio specified for massive MIMO (32-64 antennas in base station!)
|
||||
\end{itemize}
|
||||
\end{frame}
|
||||
|
||||
\begin{frame}{Antennas with many ports}
|
||||
\includegraphics[width=85mm]{multiport-antenna.jpg}
|
||||
\end{frame}
|
||||
|
||||
\begin{frame}{Where will it end?}
|
||||
\includegraphics[width=115mm]{kathrein_hepta.png}
|
||||
\end{frame}
|
||||
|
||||
\subsection{Antenna Integrated Radio}
|
||||
|
||||
\begin{frame}{Further integration}
|
||||
\begin{itemize}
|
||||
\item the radio head has moved up the tower
|
||||
\item coaxial cables are shorter than ever
|
||||
\item ... but we have more and more of them
|
||||
\item So what do we do?
|
||||
\pause
|
||||
\item Integrate radio head inside antenna!
|
||||
\end{itemize}
|
||||
\end{frame}
|
||||
|
||||
\begin{frame}{Antenna Integrated Radio}
|
||||
\begin{columns}
|
||||
\column{0.28\linewidth}
|
||||
\centering
|
||||
\includegraphics[width=36mm]{RAS.jpg}
|
||||
\column{0.70\linewidth}
|
||||
\begin{itemize}
|
||||
\item Systems like {\em Nokia RAS} / {\em Ericsson AIR}
|
||||
\item Radio heads completely integrated with antenna
|
||||
\item no coaxial cable at all
|
||||
\item CPRI over fiber directly into the antenna
|
||||
\item Everything Great? New problems
|
||||
\begin{itemize}
|
||||
\item enormous weight not suitable everywhere
|
||||
\item complicated measurements (field technicians)
|
||||
\end{itemize}
|
||||
\end{itemize}
|
||||
\end{columns}
|
||||
\end{frame}
|
||||
|
||||
|
||||
\section{back-haul, hardware, software}
|
||||
|
||||
\subsection{Evolution of cellular back-haul}
|
||||
|
||||
\begin{frame}{Classic 2G back-haul}
|
||||
\begin{itemize}
|
||||
\item 2G (GSM) was specified while ISDN was hot
|
||||
\item back-haul of GSM BTS is done via E1/T1 (ISDN PRI)
|
||||
\item E1 has 30 usable timeslots of 64kBps each
|
||||
\begin{itemize}
|
||||
\item use one for signaling (A-bis RSL + OML)
|
||||
\item use one quarter (16kBps) sub-slot for each voice call
|
||||
\end{itemize}
|
||||
\item While GSM is still deployed today, 3GPP never specified any other transport
|
||||
\item Every vendor came up with their own proprietary kludge on how to carry Abis over IP
|
||||
\end{itemize}
|
||||
\end{frame}
|
||||
|
||||
\begin{frame}{Classic 3G back-haul}
|
||||
\begin{itemize}
|
||||
\item 3G (UMTS) was specified when ATM was the next hot thing
|
||||
\item back-haul of eNodeB is done via ATM
|
||||
\item in reality, often Inverse ATM Multiplex (ATM over 4xE1 ISDN)
|
||||
\item 3GPP at least later adapted specs for IP based transport
|
||||
\begin{itemize}
|
||||
\item Every 20ms voice codec frame split over three different UDP packets. yay!
|
||||
\end{itemize}
|
||||
\end{itemize}
|
||||
\end{frame}
|
||||
|
||||
\begin{frame}{4G back-haul}
|
||||
\begin{itemize}
|
||||
\item 4G is first 3GPP cellular technology transported over IP from day one
|
||||
\item Therefore, no exotic physical layers
|
||||
\item Ethernet in most cases
|
||||
\item Problem: Where do we get clock from?
|
||||
\begin{itemize}
|
||||
\item ISDN/E1/ATM always provided clock reference
|
||||
\item Ethernet doesn't provide clock reference
|
||||
\end{itemize}
|
||||
\end{itemize}
|
||||
\end{frame}
|
||||
|
||||
\begin{frame}{IP-based back-haul and base station clocking}
|
||||
\begin{itemize}
|
||||
\item cellular base stations need super stable clock reference
|
||||
\begin{itemize}
|
||||
\item requirement of 30 ppb is almost 1000 times more accurate than crystal
|
||||
\item even ovenized crystals (OCXOs) not long-term stable enough
|
||||
\end{itemize}
|
||||
\item in the post-ISDN/PDH/SDH days, pick your poison:
|
||||
\begin{itemize}
|
||||
\item go for a GPS-DO and create a single point of failure, or
|
||||
\item use Synchronous Ethernet and loose the advantage of low-cost COTS Ethernet Switches, or
|
||||
\item use IEEE PTP and hope your switches don't introduce too much jitter, or
|
||||
\item let your base stations hammer your NTP server and pray
|
||||
\end{itemize}
|
||||
\end{itemize}
|
||||
\end{frame}
|
||||
|
||||
\subsection{Base Station Electronics}
|
||||
|
||||
\begin{frame}{Base Station Electronics: Baseband}
|
||||
\begin{itemize}
|
||||
\item Typically some multi-core DSP
|
||||
\begin{itemize}
|
||||
\item e.g. TI Keystone2 (eight 64bit 1.2GHz DSPs)
|
||||
\item built-in coprocessors (FFT, crypto, Turbo Decoder, Viterbi)
|
||||
\item built-in CPRI/OBSAI Controller
|
||||
\item four ARM Cortex A-15 for L2/L3 processing
|
||||
\end{itemize}
|
||||
\item Often also FPGAs + vendor-specific ASICs
|
||||
\begin{itemize}
|
||||
\item Ericsson big on ASICs
|
||||
\item proprietary ASICs/SoCs with 10.5 billion transistors
|
||||
\item that's comparable to Apple A12X / Huawei Kirin 990!
|
||||
\end{itemize}
|
||||
\end{itemize}
|
||||
\end{frame}
|
||||
|
||||
\begin{frame}{Base Station Electronics: Radiohead}
|
||||
\begin{itemize}
|
||||
\item Some RFIC (typically ADI)
|
||||
\begin{itemize}
|
||||
\item ADC + DAC
|
||||
\item up/downconversion (mixer)
|
||||
\item on-chip filters
|
||||
\end{itemize}
|
||||
\item Power Amplifier
|
||||
\begin{itemize}
|
||||
\item typically 2 stages of drivers + final PA
|
||||
\end{itemize}
|
||||
\item Circulator
|
||||
\begin{itemize}
|
||||
\item protect PA from power reflected back from antenna
|
||||
\end{itemize}
|
||||
\item Cavity Duplexer
|
||||
\item [Digital] [Adaptive] Pre-distortion
|
||||
\begin{itemize}
|
||||
\item Ensure Linear PA even for high-PAPR signals
|
||||
\end{itemize}
|
||||
\end{itemize}
|
||||
\end{frame}
|
||||
|
||||
|
||||
\subsection{Base Station Software}
|
||||
|
||||
\begin{frame}{Base Station Software}
|
||||
\begin{itemize}
|
||||
\item Don't expect too many familiar things here
|
||||
\item decades of proprietary development by large corporations
|
||||
\item Enea OSE (Operating System Embedded) popular with Ericsson + Nokia
|
||||
\begin{itemize}
|
||||
\item proprietary microkernel with custom-everything including filesystems
|
||||
\end{itemize}
|
||||
\item vxworks found in some equipment like Huawei radioheads
|
||||
\item Linux found mostly only in small cells, inheriting software from femtocells
|
||||
\end{itemize}
|
||||
\end{frame}
|
||||
|
||||
\begin{frame}{Further Reading}
|
||||
\begin{itemize}
|
||||
\item \url{http://cpri.info/}
|
||||
\item FlexiWCDMA teardown: \url{https://www.youtube.com/watch?v=d5xT4p9FXIw}
|
||||
\item Ericsson RBS600 teardown: \url{https://www.youtube.com/watch?v=qO127zY3voE}
|
||||
\end{itemize}
|
||||
\end{frame}
|
||||
|
||||
\begin{frame}{Thanks}
|
||||
Thanks for your attention.
|
||||
|
||||
You have a General Public License to ask questions now :)
|
||||
\end{frame}
|
||||
|
||||
\end{document}
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