Speaker 1: You know, it's pretty wild when you stop and think
Speaker 1: about it. Every time you make a call or send
Speaker 1: a text, you can just load a webpage. Your phone
Speaker 1: is talking this like secret language, tapping into this massive
Speaker 1: invisible network, towers, other devices. It's all happening constantly without
Speaker 1: you really noticing the nuts and bolts. Welcome to the
Speaker 1: deep dive today. We're going to try and unravel that
Speaker 1: hidden language. We're tracing the whole evolution of mobile networks,
Speaker 1: you know, from those first crackly digital calls, all the
Speaker 1: way up to super fast five G, and we'll even
Speaker 1: touch on Wi Fi and Bluetooth, the local stuff. Our
Speaker 1: mission really is to pull out the key insights from
Speaker 1: some expert sources. We've got this great text that maps
Speaker 1: the journey gsm U, MTS, LTE, five G, double Land, Bluetooth.
Speaker 1: The idea is to give you a shortcut, help you
Speaker 1: get how this connected world ticks without drowning and text speak.
Speaker 1: It's a huge leap bran from just voice to all
Speaker 1: this complex data streaming around. And there are some genuinely
Speaker 1: surprising bits of tech inside your phone you might not
Speaker 1: even know about.
Speaker 2: Absolutely, And what I find fascinating is how each general, Well,
Speaker 2: it builds on the one before. It's often solving problems
Speaker 2: you didn't even realize were problems. It really is like
Speaker 2: a symphony of engineering just to keep us all talking, texting, streaming, connected.
Speaker 3: Okay, let's rewind way back GSM two g before smartphones
Speaker 3: really took off. Yeah, how did your voice actually, you know,
Speaker 3: travel wirelessly to someone else? I seems basic.
Speaker 2: Now, but back then it was revolutionary. Really, GSM set
Speaker 2: the stage for digital mobile comms. You had a few
Speaker 2: core components. The Mobile Switching Center the MSSE. Think of
Speaker 2: it as the brain, handling call routing, knowing where you were,
Speaker 2: and it worked with the Home Location Register the HLR.
Speaker 2: That's basically the big database holding your subscriber info, your
Speaker 2: number services.
Speaker 3: Okay, so the network knows who you are and where
Speaker 3: you are roughly, but getting the voice signal itself over
Speaker 3: the airwaves that limited resource. How did they squeeze it
Speaker 3: in efficiently? This is where it gets really clever.
Speaker 2: I think you're right. That's where the transcoding and rate
Speaker 2: adaptation you died, the TRAU came in. It was a
Speaker 2: critical piece. See inside the main network, your digitized voice
Speaker 2: used something called PCM took up about sixty four kilobits
Speaker 2: per second, pretty chunky. The tierrau's job was to compress
Speaker 2: that like, squash it down in real time, often to
Speaker 2: around thirteen kilobits per second for the radio part. Imagine yeah,
Speaker 2: a big truck of data and needing to get through
Speaker 2: a narrow tunnel. The TREU made it fit. It meant
Speaker 2: more people could share the same limited airwaves, and that
Speaker 2: compression technology kept improving. GSM introduced AMR Adaptive Multi Rate
Speaker 2: Codex and then AMR Wideband or AMRWB. This was huge
Speaker 2: for quality. AMRWB digitized a much wider frequency range, up
Speaker 2: to seven thousand hertz compared to like thirty four hundred
Speaker 2: hertz before. Suddenly voices sounded much richer, more natural, less
Speaker 2: telephony if you know what I.
Speaker 3: Mean, definitely. So voice was sorted getting more efficient, sounding better.
Speaker 3: But then came the desire for data. Remember the WAP
Speaker 3: that's super slow early mobile Internet. What was the hurdle
Speaker 3: there and how did TPRs two point five g.
Speaker 1: Tackle it right?
Speaker 2: GPRS it was essentially the packet's switched add on to
Speaker 2: the circuit switched voice network. It used a different node
Speaker 2: the serving GPRS support node SGSN. The key difference was
Speaker 2: how it used the air interface. GSM Voice gave you
Speaker 2: a dedicated channel, a traffic channel for your whole call,
Speaker 2: even during silence. GPRS introduced the Packet Data Traffic Channel PDTCCH.
Speaker 2: This could be shared. Your phone only used a timeslot
Speaker 2: when it actually had data packets to send or receive.
Speaker 2: Much more efficient for that bursty web browsing or sending
Speaker 2: an early MMS and.
Speaker 3: Moving around or getting an incoming call. There were protocols
Speaker 3: coordinating all that behind the scenes, right exactly.
Speaker 2: The Mobile Application Part or MAP protocol was key for that.
Speaker 2: It let the network like the ms E equery of the
Speaker 2: HLR to find out which tower you were currently near.
Speaker 2: That's how calls found you. And underneath MAP you had
Speaker 2: Signaling System number seven S seven protocols. These came from
Speaker 2: the fixed line world but were adapted for mobile over time.
Speaker 2: They even started running the lower layers over IP and Ethernet.
Speaker 2: More modern, more flexible.
Speaker 3: Okay, fast forward a bit too. Thousands umts, the third
Speaker 3: generation three G. This is where mobile data started to
Speaker 3: feel well usable. What was the big technical shift?
Speaker 2: The fundamental change with UMTS was the move to code
Speaker 2: division multiple access CDMA. Instead of slicing up time or
Speaker 2: frequency like GSM did, CDMA lets everyone share the same
Speaker 2: frequency band at the same time. Users are separated by
Speaker 2: unique mathematical codes spreading codes. The radio network changed too,
Speaker 2: It was called you Dream. It had nodeBs, which are
Speaker 2: like the base stations and radione or controllers RNCs managing
Speaker 2: groups of nodeBs, and your phone became user equipment or UE.
Speaker 3: Huh So if everyone's using the same frequency, doesn't that
Speaker 3: cause like interference? How does that work?
Speaker 2: That's a great point, and yes it does. It leads
Speaker 2: to this really interesting effect called cell breathing, because everyone's
Speaker 2: signal is technically interference to everyone else in that cell.
Speaker 2: As more people join, the overall interference level goes up
Speaker 2: to cope. Phones and the NodeB have to transmit with
Speaker 2: more power to be heard over the noise and the
Speaker 2: The side effect of needing more power is that the
Speaker 2: maximum reliable distance shrinks, so the cell's coverage area literally
Speaker 2: contracts when it's busy and expands when it's quiet.
Speaker 1: It breathes.
Speaker 3: Wow, okay, cell breathing. That's not something you'd intuitively think about.
Speaker 3: So building on that, things got faster again with HSDPA
Speaker 3: and HSPA plus. Buy that felt like a real speed boost.
Speaker 3: What was the secret sauce there?
Speaker 2: Yeah, HSDPA High Speed Downlink Packet Access was a big
Speaker 2: step up for speed. One key thing was moving away
Speaker 2: from dedicated channels just for you to using shared channels
Speaker 2: the hfdsch and importantly, the scheduling deciding who gets to
Speaker 2: transmit when moved closer to the user down to the
Speaker 2: node b this myth the network could react much faster
Speaker 2: to changing radio conditions, allocating resources more efficiently. That pushed
Speaker 2: speeds up significantly. HSTPA got you maybe fourteen megabits per second,
Speaker 2: ideally HSPA plus went even further over thirty. That's when
Speaker 2: mobile web browsing really started to feel okay. They also
Speaker 2: introduced things like continuous packet connectivity cpclater on to try
Speaker 2: and reduce battery drain during those gaps when you weren't
Speaker 2: actively transmitting data but wanted to get back online quickly.
Speaker 3: Right, battery life is always a concern, so the phone
Speaker 3: wasn't just always on full blast.
Speaker 1: It had different modes exactly.
Speaker 2: UMTS defined Radio Resource Control RC states if you were
Speaker 2: actively streaming or on a call, you'd be in a
Speaker 2: state like cell DCCH with dedicated resources high power, but
Speaker 2: for smaller bursty things checking email background updates, you might
Speaker 2: be in sell AVCH using shared resources lower power. The
Speaker 2: network couldn't guarantee a data rate or delay in FACCH,
Speaker 2: kind of like best effort ethernet, but it saved a
Speaker 2: lot of battery. It's always a trade off. And one
Speaker 2: more clever thing in UMTS mobility was soft handover. Remember
Speaker 2: how in GSM you'd kind of drop one tower just
Speaker 2: before picking up the next. With soft handover, your phone
Speaker 2: could actually be connected to multiple nodeBs simultaneously for a
Speaker 2: brief period during the transition. It made handovers much smoother
Speaker 2: or fewer dropped calls, especially as you move between cells
Speaker 2: controlled by different R and CS that could coordinate via
Speaker 2: an interface.
Speaker 3: Call ir okay onto LTE four G. This really changed everything,
Speaker 3: didn't it. Streaming HD video on your phone became normal.
Speaker 3: What was the absolute biggest shift.
Speaker 2: With LTE The philosophy changed completely. LTE was designed from
Speaker 2: the ground up as a pure IP network that circuit
Speaker 2: switched rests. Stuff from GSM and u MTS gone. It
Speaker 2: was all data packets now, voice itself just became another
Speaker 2: application running over the IP data network, and the core
Speaker 2: network got flatter, fewer different kinds of boxes, which helped
Speaker 2: reduce latency that delay. You sometimes notice it made everything snappier.
Speaker 3: Wait, hold on, if circuit switching is gone, how do
Speaker 3: you make a normal phone call? Isn't that still essential?
Speaker 2: Good question? That's handled by volty voiceover LTE. It uses
Speaker 2: a framework called the IMS, the IP Multimedia Subsystem to
Speaker 2: manage voice calls as IP data streams. Crucially, VOLTI gets
Speaker 2: special treatment. It uses dedicated bearers in the network. That
Speaker 2: means the network guarantees quality of service, low latency, consistent
Speaker 2: bandwidth essential for a good call quality, and they even
Speaker 2: use unacknowledged mode data radio bears UMDRB for voice packets.
Speaker 2: The idea is if a tiny bit of voice data
Speaker 2: gets lost, it's better to just keep going rather than
Speaker 2: retransmitting it late, which would just sound garbled anyway. Plus
Speaker 2: SRVCC single radio Voice call continuity handles the handover if
Speaker 2: you move out of four G coverage mid call, dropping
Speaker 2: you back to three G or two G voice without
Speaker 2: losing the call.
Speaker 3: Okay, that makes sense. So the speed ltefl fast What
Speaker 3: were the key radio technologies making that happen, Things like
Speaker 3: OFDM and.
Speaker 2: MIMO exactly OFDM. Orthogonal frequency division multiplexing is quite clever.
Speaker 2: Instead of using one wide radio channel, it splits it
Speaker 2: into hundreds, sometimes thousands, of very narrow subcarriers, all orthogonal,
Speaker 2: meaning they don't interfere with each other. Think of it
Speaker 2: like having many small parallel pipes instead of one big one.
Speaker 2: It makes the signal much more robust against things like
Speaker 2: echos or reflections. And then MIM multiple input multiple output.
Speaker 2: This is huge. Uses multiple antennas on the base station
Speaker 2: and on your phone to send multiple data streams at
Speaker 2: the same time over the same frequency band. If you
Speaker 2: have say two antennas two by two MIMO, you can
Speaker 2: potentially double your data rate. Four antennas four by four
Speaker 2: MIMO potentially quadruple it. It's a massive capacity booster.
Speaker 3: And for the really high speeds, didn't they start gluing
Speaker 3: different frequency bands together like creating wire highways precisely?
Speaker 2: That's carrier aggregation or CAA. An operator might have licenses
Speaker 2: for spectrum in different bands. CAA lets them combine several
Speaker 2: of these carriers, maybe up to twenty miliherds each into
Speaker 2: one logical wider channel for your phone, so instead of
Speaker 2: just a twenty milliahurtz channel, you might get forty sixty
Speaker 2: or even more, directly increasing your potential peak speed. It's
Speaker 2: more common and powerful for downloads, though uplink CA is
Speaker 2: trickier because your phone's battery and power output are limiting factors.
Speaker 3: Makes sense now, Battery life again always crucial. How did
Speaker 3: LTE improve things there? Especially for all those connected devices
Speaker 3: popping up the Internet of Things?
Speaker 2: LTE brought in more sophisticated power saving. When your phone
Speaker 2: is connected but not actively transferring data, it can use
Speaker 2: discontinuous reception DRX. It basically agrees with the network to
Speaker 2: switch off its radio receiver for short periods and only
Speaker 2: wake up at specific intervals to check if there's data waiting.
Speaker 2: And for those IoT devices that only need to send
Speaker 2: tiny bits of data very infrequently, think sensors meters, LTE
Speaker 2: introduced Power Save Mode PSM and Extended Idle Mode DRX EDRX.
Speaker 2: These let devices go into a really deep sleep, powering
Speaker 2: down their radio almost completely for potentially hours, days, even weeks,
Speaker 2: and only waking up periodically. Huge battery savings for those
Speaker 2: use cases. And another efficiency booster, particularly for volty and
Speaker 2: those loaded IoT devices, is robust header compression OHC. IP packets,
Speaker 2: especially with UDP and rtpus for voice, have quite large
Speaker 2: headers relative to the actual voice data. ROHC compresses these headers,
Speaker 2: significantly reducing the amount of data sent over the air.
Speaker 2: Every bit saved helps with battery and network capacity.
Speaker 3: And moving between network types, like if you drive from
Speaker 3: a four G area into a three G only zone,
Speaker 3: how did LTE handle that gracefully?
Speaker 2: LTE was designed for smooth interconnection with UMTS and GSM.
Speaker 2: Your phone performs procedures like location area updates or routing
Speaker 2: area updates when it moves between network types. The core
Speaker 2: network nodes, the MME and LTE and the SGSN and
Speaker 2: two G three G can exchange your subscriber context information.
Speaker 2: This ensures your ongoing data session or call can be
Speaker 2: maintained seamlessly as you switch technologies. It's designed to be
Speaker 2: pretty invisible to you, and it's worth mentioning. The hardware
Speaker 2: shift to the core network equipment itself changed. We moved
Speaker 2: away from expensive proprietary boxes towards using more standardized Intel
Speaker 2: by eighty six, servers. Combined with concepts like network function
Speaker 2: Virtualization NFV and later cloud native principles, especially heading towards
Speaker 2: five G, it gave operators much more flexibility, scalability, and
Speaker 2: often lower costs. They could spin up network functions like
Speaker 2: software on standard.
Speaker 3: Hardware right which brings us to now five G. We
Speaker 3: hear about it constantly, beyond just being fit aster four G.
Speaker 3: What's fundamentally new? We're different about five G.
Speaker 2: New radio five G does bring several genuinely new things.
Speaker 2: One big one is the expansion into new frequency bands.
Speaker 2: We have frequency range one FR one, which is below
Speaker 2: six gigaherts, similar bands to four G, but five G
Speaker 2: can use wider channels within them up to one hundred
Speaker 2: minie herts. But then there's frequency range two FR two
Speaker 2: to the millimeter mill wave bands. These are much higher
Speaker 2: frequencies like twenty four gigaherts and above. The huge advantage
Speaker 2: of millimwave is massive available band with carriers up to
Speaker 2: four hundred milliherts wide. This enables those multi gigabit speeds
Speaker 2: you hear about the downside physics, Those high frequencies don't
Speaker 2: travel for maybe tens or hundreds of meters and they're
Speaker 2: easily blocked by walls, even leaves on trees. So millimwave
Speaker 2: is great for specific hotspots stadiums, busy streets, airports, but
Speaker 2: not for wide area coverage.
Speaker 3: Okay, so different frequencies for different scenarios. Yeah, but deploying this,
Speaker 3: how do operators manage putting five G in places that
Speaker 3: already have four G without needing double the antennas and
Speaker 3: spectrum everywhere.
Speaker 2: That's a key challenge, and the answer is dynamic spectrum
Speaker 2: sharing DSS. DSS is a clever software feature that allows
Speaker 2: a base station to transmit both fur GLTE and five
Speaker 2: GNR signals in the same frequency band at the same time.
Speaker 2: It dynamically allocates the time and frequency resources within that
Speaker 2: band between four G and five D users based on
Speaker 2: demand millisecond by millisecond, so an operator can upgrade a
Speaker 2: site to support five G using their existing four G
Speaker 2: spectrum and serve both types of users efficiently. As the
Speaker 2: number of five G devices grows, it smooths the transition massively.
Speaker 2: And five G isn't just about the radio. There's the
Speaker 2: option of a completely new core network architecture called five
Speaker 2: G Standalone SSA. This introduces new more modular core network functions,
Speaker 2: things like the access management function AMF for handling connections
Speaker 2: and mobility, the session management function SMF for managing your
Speaker 2: data sessions, and the user plane function UPF, which actually
Speaker 2: forwards your data packets. This service based architecture is designed
Speaker 2: to be cloud native, more flexible, and enables advanced features
Speaker 2: like network slicing.
Speaker 3: So it sounds like the brain of the network out
Speaker 3: a major overhaul two, more flexible, more software driven.
Speaker 2: Exactly the five G core network procedures for things like registration,
Speaker 2: connection management, session establishment, mobility. They're all redesigned to be
Speaker 2: more granular and suited for this virtualized cloud environment. And
Speaker 2: for mobility between five G based stations called GMB's. There's
Speaker 2: the XN interface, which is analogous to the X two
Speaker 2: interface and LTE, allowing fast handovers directly between base stations
Speaker 2: without always involving the core network. Security also gets a
Speaker 2: boost in five G. For instance, when your phone first connects,
Speaker 2: it can use a subscription concealed Identifier SUCI instead of
Speaker 2: sending your permanent identifier MSI in the clear. This helps
Speaker 2: protect your privacy against tracking and the main authentication process
Speaker 2: verifying you are who you say you are is anchored
Speaker 2: more strongly in your home network, making things more secure,
Speaker 2: especially when roaming.
Speaker 3: Okay, let's step away from the big cellular networks for
Speaker 3: a moment. Our devices also rely hugely on local wireless
Speaker 3: tech Wi Fi and Bluetooth. What makes the tick and
Speaker 3: how do they fit into the picture?
Speaker 2: Right? Wi Fi or technically w Lan based on IE
Speaker 2: eight to two point one one standards, it comes in
Speaker 2: a few flavors. You'd have ad hoc mode, where devices
Speaker 2: connect directly peer to peer, not super common for most users.
Speaker 2: Much more typical is a basic service set BSS. That's
Speaker 2: your home Wi Fi router, the access point or AP,
Speaker 2: and the device is connected to it. Than in larger
Speaker 2: places like offices or campuses, you have an extended service
Speaker 2: set ESS, which is multiple aps connected together, usually by wires,
Speaker 2: appearing as a single network so you can roam seamlessly.
Speaker 3: Got it now that crowded coffee shop scenario wi Fi
Speaker 3: slows down? You mentioned interference before with cdma's or something
Speaker 3: similar in Wi Fi.
Speaker 2: Yes, absolutely, Wi Fi uses a shared medium, the airwaves.
Speaker 2: A classic problem is the hidden station problem. Imagine you
Speaker 2: and someone else are both connected to the same Wi
Speaker 2: Fi hotspot, but you're too far apart to hear each
Speaker 2: other directly. If you both try to transmit to the
Speaker 2: access point at the same time, your signals collide at
Speaker 2: the AP and neither gets through cleanly. To help with
Speaker 2: Wi Fi has an optional mechanism called RTSCTS Ready to
Speaker 2: Send Clear to Send. A device can send an RTS request.
Speaker 2: The AP broadcasts the CTS message, telling everyone else to
Speaker 2: be quiet for a bit. It reserves the air, helps
Speaker 2: avoid collisions, but adds overheads, so it can reduce overall throughputs.
Speaker 3: And Wi Fi keeps getting smarter too. Writ Newer versions
Speaker 3: like Wi Fi five and six use beam forming. How
Speaker 3: does that work? Sounds like Sci Fi?
Speaker 2: It's pretty neat. Instead of the access point just blasting
Speaker 2: the signal out equally in all directions, beamforming tries to
Speaker 2: focus the transmission towards where your device actually is. The
Speaker 2: AP sends out a sounding packet, Your device measures how
Speaker 2: that signal arrived, and sends back feedback. Using that feedback,
Speaker 2: the AP calculates how to adjust the signals from its
Speaker 2: multiple antennas so they combine constructively at your device's location.
Speaker 2: It results in a stronger signal for you better speeds
Speaker 2: and potentially less interferance for others.
Speaker 3: Cool. Okay, last one. Bluetooth headphones, speakers, smart watches connects
Speaker 3: everything nearby. How does it juggle all those connections without
Speaker 3: turning into gear chaos?
Speaker 2: Bluetooth uses small personal networks called pecanets. One device is
Speaker 2: the master, like your phone, and it can talk to
Speaker 2: up to seven active slave devices like headphones, a keyboard,
Speaker 2: et cetera. To let lots of these picanetes operate in
Speaker 2: the same space, like in an office or on a bus.
Speaker 2: Bluetooth uses adaptive frequency hopping AFH. It rapidly hops between
Speaker 2: dozens of different channels and the two point four giblhertz
Speaker 2: band following a pseudorandom sequence. But crucially it's adaptive. It
Speaker 2: learns which channels are noisy or occupied, maybe by Wi
Speaker 2: Fi or other Bluetooth devices, and avoids them.
Speaker 3: And the battery life on Bluetooth devices is often amazing.
Speaker 3: How does it manage that?
Speaker 2: Power saving is baked into Bluetooth Devices can agree to
Speaker 2: enter low power states like sniff or hold. In sniff mode,
Speaker 2: a slave device only wakes up to listen for packets
Speaker 2: from the master at pre agreed intervals, maybe every few
Speaker 2: hundred milliseconds, instead of listening constantly. Hold mode lets a
Speaker 2: device power down its transceiver completely for a set period.
Speaker 2: These drastically cut down power can some when there's no
Speaker 2: active data transfer. And then there's Bluetooth Low Energy Ble,
Speaker 2: which is a whole different flavor, really optimized for ultra
Speaker 2: low power. It's designed for things like sensors, fitness trackers,
Speaker 2: smart home gadgets that only need to exchange small amounts
Speaker 2: of data very occasionally. It uses a different way of
Speaker 2: communicating based on reading and writing attributes or variables using
Speaker 2: protocols called att and gay ett. Very efficient for those
Speaker 2: simple sense status update type tasks hashtag tag outro Wow.
Speaker 1: Okay.
Speaker 3: So from these globe spanning cellular networks that have evolved
Speaker 3: generation by generation right down to the personal bubble of
Speaker 3: connectivity around us with Wi Fi and Bluetooth, it's just
Speaker 3: incredible the sheer amount of engineering and constant innovation that
Speaker 3: makes it all work so seamlessly most of the time.
Speaker 3: It really is like a hidden language our devices are
Speaker 3: speaking constantly.
Speaker 2: It absolutely is, and it makes you wonder, doesn't it.
Speaker 2: As these different networks cellular Wi Fi, maybe even others
Speaker 2: become even more tightly integrated, smarter. How will that change
Speaker 2: how we think about being connected? What does that seamless
Speaker 2: handoff between different kinds of networks mean for our daily lives,
Speaker 2: for future applications we haven't even conceived of yet.
Speaker 3: That's a great thought to end on. So the next
Speaker 3: time you pull out your phone, maybe take just a
Speaker 3: second to appreciate that silent, incredibly complex dance as signals
Speaker 3: happening all around you. What part of this journey through
Speaker 3: mobile networks surprised you the most? We hope this deep
Speaker 3: dies gave you some new insights into the invisible world
Speaker 3: keeping us all connected.