 Towards the end of last last week we mentioned that okay, why what do we benefit from doing from using wireless communications? We don't need wires we can be mobile and But to get them we have a number of challenges to address in that compared to wired communications while the wireless channel or the wireless Any wireless communications is generally performs worse than wired communications So we need to deal with that not just performance sometimes sometimes security is a problem as well We won't try and deal with that in this course security And we come up or we summarized a simple model for wireless transmission where we have some transmitter Takes an electrical signal and the antenna transmits some signal To a receiver we transmit at some power level our output signal The antenna in fact introduces some gain it increases the strength of the signal The signal Attenuates it gets weaker as it travels across some distance It's received at some Signal strength by the receiver the receiving antenna introduces some gain and we get the final Received signal power PR and typically with devices with receivers in particular we The received signal must be strong enough such that the device can decode the data that was transmitted in that signal It depends upon how that device was Was built the characteristics of the device in this course we primarily care about The distance at which we can transmit How far can we transmit at some transmit power such that the receiver can receive and decode the data? We'll make some simplifying assumptions like if we have a transmission range of 10 meters We'll assume that if our transmitter and receiver are separated by 11 meters. They will not be able to communicate Okay, that's if you hear transmission range. It's the maximum distance at which the transmitter and receiver can communicate successfully in practice, it's not that clear cut and that Okay, sometimes at 10 meters 10 and a half meters, it will be okay in other cases nine meters It'll be okay, so that the range is not a Clear cut number, but for our simple analysis We'll assume many of the why wireless technologies we look at have some approximate range at which they can transmit We're interested in the range because if we're going to deploy a network to provide some coverage of an area So provide access to everyone within some area Then the range at which our say our base station or access point transmits Impacts upon how many people that will cover the larger the range the more people it will cover So that's one reason we care about the range our device transmits with some power when we talk about mobile devices the transmit power is important because The more transmit power we use the more power or the more energy that the the the wireless transmitter consumes of your battery so The higher the transmit power the further we can transmit. That's a good thing But the higher the transmit power the more energy we need to consume for the device That is the faster your battery will go flat on your mobile device especially So we want a high transmit power for high range But we want a low transmit power to consume battery life to preserve battery life We care about data rate often. We're talking about how fast can we send our data many applications the the data rate is important for Determining the performance of the application. So generally we'd like higher data rate We care about the frequency at which we transmit our signals Because of several reasons different frequencies have different physical characteristics some signals in the infrared frequency cannot pass through walls but Wi-Fi signals Using a different frequency can pass through walls. So depending upon our usage scenario the frequency is important Also, some frequencies are it considered what's in what's called the unlicensed band You don't need a license to use them You don't have to pay money to use them Wi-Fi is an example Other frequencies are licensed to use them. You need to pay money So you need to consider the frequency from the perspective of the cost And another thing we care about frequency is because if I'm using one frequency and someone nearby uses the same frequency Our signals may interfere with each other and the receiver will not be able to successfully receive the data So I'd like to use a frequency that someone else nearby is not using So choosing the right frequency is important data rate. We care about range frequency transmit power we care about and When we choose a wireless technology, we'd like to minimize cost when we talk about a a The transmission of a wireless signal. In fact, we don't transmit at one frequency We transmit a signal which is made up of multiple components a range of frequencies So If we try to draw that on Some plot where this is some frequent the frequency on this axis and this is the signal strength or some power level then When we transmit a signal say your laptop sends a signal to a Wi-Fi access point that signal covers a range of frequencies and What I'll try and draw it may look something like this where the signal Has some center frequency So the center point here And but the signal has power a high power level for a range of frequencies so And about these points Let's call this the minimum Frequency component and the maximum for our signal and the difference between them is The bandwidth of our signal so in fact we transmit a signal which covers a range of frequencies Where that range of frequencies is the bandwidth of that signal. So this is the bandwidth in Practice or in theory it would be nice. It was a square plot here in practice. It's not square. There's some Curvature here What that means is which when we transmit a signal say from my laptop It's got high power at these frequency At these frequencies very low power at these frequencies and close to zero power here So it's as if there's no Transmission at these frequencies and and beyond Up to infinity when we talk about wireless Technologies often you hear about the frequency and it's usually refers to the approximate center frequency an Example is wireless LAN use that Wi-Fi What's the frequency used for wireless LAN anyone know or can hurt may have heard it or even see in the lecture notes wireless LAN 2.4 gigahertz so the most common frequency Used for wireless LAN transmissions is 2.4 gigahertz But what does that mean? In fact when we transmit a signal we transmitted a range of frequencies. This is the approximate center frequency In fact, there are specific values. I don't have them on these slides. I Want to talk about wireless networks. I want to show you some wireless devices today But I cannot get my Wi-Fi to work on the laptop. This is the difficulty of wireless communications for Wi-Fi For example, and I cannot remember the exact value the center frequency may be Two Let's say two four one oh megahertz 2.41 gigahertz because with Wi-Fi in fact we have multiple channels and Each channel has a different center frequency So for an example the center frequency of this signal may be 2.4 one oh gigahertz or 2,410 megahertz the bandwidth of a Wi-Fi signal is I think Around 20 megahertz So in fact when I my laptop transmits it transmits signals across a range of frequencies Where the minimum is in this example what? 2400 megahertz and the maximum would be 2420 megahertz You see the difference 20 megahertz center 2410 megahertz So when we talk when you hear the frequency of Wi-Fi is 2.4 gigahertz It's an approximation of the center frequency. In fact, there are multiple center frequencies depending upon the channel Available so we care not just about the center frequency of our signal But also the bandwidth consumed of that signal Because if I transmit a signal with a center frequency of 2.41 gigahertz and a bandwidth of 20 megahertz someone nearby May transmit a signal on a different frequency to avoid interference We'd like their transmission not to overlap with mine in the frequency spectrum So someone else may transmit a signal With a different center frequency, let's say 2,440 megahertz Same bandwidth 20 megahertz So therefore ranging from 2430 up to 2450 and in this case two people can transmit One transmitting this signal the blue one and another user in the same location transmitting this red signal and Because they do not overlap They will not interfere with each other If they overlapped then we can cause interference at the receiver and we would not successfully receive data So the bandwidth and the center frequency that we use is important To know so we know that we will not over or we're not interfere with someone else the large of the bandwidth Then if we have to share with other people the less Range of frequencies that other users can use So we try to minimize the bandwidth so that we do not interfere with others But we generally try to maximize the bandwidth to increase the performance the data rate So they're innate the range of trade-offs to deal with with the frequency management the frequency and the bandwidth impact upon the data rate impact upon the transmission range how far we can send interference and the cost Because some frequencies are licensed and therefore have some cost associated So it's important to choose the right frequency and bandwidth such that it meets your requirements any questions about this concept here about center frequency bandwidth We don't send a signal at just one frequency. In fact, it contains a range of frequencies Some of you may remember some lectures from previous semesters that look at the the sinusoid functions s of t equals sine 2 pi t plus sine 2 pi 2 pi 3 ft and so on it's related to this and multiple components Any questions before we move on away from frequencies? In fact, we'll see the details of Wi-Fi in One or two topics time where we cover wireless LAN in detail and I'll show you the exact frequencies This is just an example. I don't know if it's exactly this value This just shows the spectrum available for most communication signals ranging from Hertz up to visible light optical fiber, okay, so some wireless We see some wireless technologies and as well as others so FM and radio TV some satellite transmissions infrared optical fiber for light transmissions Who gives you a frequency normally that managed by international? organizations ITU and others and Then within countries by national organizations, so you cannot just go and transmit on any frequency. It's illegal So you need to get a license or use one of the unlicensed bands Let's move on one or two more general concepts before we look at some example technologies with wireless transmission we Can generally classify between a point-to-point topology and a multi point point-to-multi point topology Point-to-point is when we use highly directional antennas We have an antenna that concentrates the energy of us of our signal in to one direction and In the other directions the energy is very weak and Therefore to receive successfully the receiving antenna must be located in the direction that the transmitter is pointed That is we have two antennas pointing at each other if we slightly turn one of the antennas They will not be able to communicate So you need to carefully align the antennas for a point-to-point link We can generally transmit over larger distances with point-to-point transmission But it's more inconvenient in that you need to set up the antennas What about my laptop point-to-point or point-to-multi point do you think? When you use your wireless LAN on your laptop, do you have to place your laptop in the right orientation to get a signal? No, it's not really a point-to-point wireless transmission the antenna on your laptop is Not very directional It transmits energy Approximately equal in all directions that way that way up and down. It's slightly different, but It's not all going in one direction So your laptop is considered a pointer multi-point topology Sometimes called broadcast radio It's a radio signal broadcast mean send everywhere Don't send in one particular direction to one particular destination Point-to-point is more inconvenient in that you need to set up the antennas Same with your satellite some satellite TV You need to point the receiving antenna at the satellite if you put it in the other direction Then you will not receive the signal With point-to-multi-point. It's much more convenient because we do not need to configure where the antennas are pointed but We get more problems with interfering with people and we'll see that in detail with wireless LAN in the last four or five Slides, I'm just going to go through some example wireless technologies My slides are getting quite old Some of I haven't updated for two or three years even longer in some of the other other topics But the concepts all apply in some cases some of the data that I use in the recent years has Changed that is some of the speeds are this tier may have even gone up I'll mention them and I'll give you some other examples if there's a Significant difference from what I show on the slides to what's current today We'll look at different wireless technology starting with short-range wireless communications. So communicating across a distance of Centre meters meters, maybe tens of meters What do we have available to do that? I think you know Bluetooth Bluetooth you can send from a headset to your mobile phone over one or two meters maybe Different infrared technologies not so common today, but in the past most Laptops had an infrared receiver or infrared port for infrared communication and other technologies Zigbee is a One technology you may have heard of IEEE 802 dot 15 dot 4 is a short-range wireless Communications technology Why do we use short-range wireless comms? To connect devices together in many cases a Wireless desktop as an example connect your keyboard mouse monitor all together without cables Okay, not so much for mobility a little bit of mobility there, but mainly for convenience Who's interfering? Who's hacking into my wireless network? Connecting devices together you carry with you. Okay, you know about examples there And more so today in automation in in factories in houses in buildings of collecting data controlling systems Controlling and monitoring devices So Installing sensors throughout an area throughout a factory for example sensing the environment censoring what's happening sensing the robots doing things in a factory and Monitoring what's happening and in some cases controlling what's happening via communicating wirelessly between those sensors some example characteristics of some selected technologies Bluetooth uses The frequencies approximately 2.4 gigahertz the same as wireless LAN or Wi-Fi So you can't have interference between a blue Bluetooth link and a wireless LAN link Bluetooth There's been revisions over time the data rates less than several megabits per second, but in fact has gone up You can get higher speed Bluetooth tries to be low power so the power consumed by the transmitter Or the power can the transmit power is about several milliwatts So that you can have a Bluetooth device that has a small battery inside it, which will last for a long time The higher the transmit power the lot less time that battery will last range is usually in the order of several meters with Bluetooth Zigbee and More so now IEEE 802 dot 15 dot 4 is used develop for short-range communications, especially for automation control and monitoring systems Can transmit at different frequencies? 915 megahertz and also at the same 2.4 gigahertz Low data rates so it's designed not for speed But for low power consumption and low cost It's for things where we don't need to transfer files We just want to monitor maybe every few seconds collect a small piece of data We don't need a high data rate. We're talking about hundreds of kilobits per second but for such applications and tens of meters and There are a few others Infrared not so common today ultra wide band is another one These are some example. They're not so good to look at if you open them up You would this is an eye a inside. There's a board which is and you can pass around you may be able to see inside This one has two boards in it. They they are Small boards which support 802 dot 15 dot 4 okay, which is Used also by Zigbee. It's for why they're called wireless sensors They take two double-a batteries so you can open the case and you see there's no batteries inside them but they just take two double-a batteries and They also have some sockets to plug in in fact on board they have a temperature sensor and an accelerometer and You can plug in other sensors. We've got a few other sensors like this one's a humidity and temperature sensor. This is a light sensor it senses light the idea is that Okay, you put some batteries in them you locate them in across some building or across some area They sense some something about the physical environment. They sense the temperature The light they sense motion and so on and then they report that data back to some central computer and Maybe some of that central computer can monitor what's happening or Maybe can control what's happening for example sense the temperature If it goes above some level turn on the air conditioners automatically and turn on on and off lights and so on so they communicate using 802 dot 15 dot 4 so it data rates which is similar to Zigbee data rates of hundreds of kilobits per second at a frequency of 2.4 gigahertz and Again because they use a low transmit power With two double-a batteries in them they should last for days weeks and possibly months in some cases if anyone wants to use them for any any Great idea then we have about 10 or 11 of those wireless sensor devices. You can build your own network Next step up. Okay from short range several meters up to medium range or What we commonly know is Wi-Fi or wireless lands wireless local area networks covering a room An office area a building and sometimes a little bit further Ranges from meters to hundreds of meters depending upon the configuration There have been different technologies for wireless lands in the past But the main one used today we all know and use is based on the standard IEEE 82 dot 11 and It's been enhanced over time different Enhancements, so you would have heard of 11a 11b 11g 11n which are just enhancements of the technology improvements, you know where it's used Okay, you use it on the daily basis Typically used in a point-to-multipoint configuration like I said the laptop transmits its signal in all directions and As long as an access point is within range it can receive and communicate The most common frequency is 2.4 gigahertz But there's another one which is Is available which is 5 gigahertz? And there are some differences in the characteristics of those frequencies One of them being that with 5 gigahertz generally the distance is much much less But there's less interference There are less people using the 5 gigahertz frequency than using 2.4 gigahertz and the range And you would know from your own experience is in the order of Several meters tens of meters possibly hundred meters if we get outdoors It depends upon the obstructions in the in the vicinity and The data rates in the past range for several megabits per second 11 megabits per second and now When you buy a new laptop usually supports at least 54 megabits per second most likely up to Hundreds of megabits per second We're going to spend an entire topic looking at how that works our wireless LAN works and we'll come back to see that the specific frequencies how they work and you'll You've used them on a daily basis that the wireless LAN access points how they work and How to set them up so we won't go into detail here Next step up over a larger distance is or a different application Even is point-to-point fixed wireless after turn off my wireless Point-to-point fixed wireless point-to-point means we're typically using a Point-to-point topology we have one antenna highly directional antenna pointing at another and Fixed means those antennas are fixed in some position. We don't have mobility in this case We'll see some exceptions when we go through some examples there have been in the past some Products that provide this technology which depended upon the company So Motorola had their own way for doing it other companies had their different way They could not interoperate if you wanted a link from this campus to the rung seat campus in The past you'd buy from one company You couldn't buy equipment from two different companies, but nowadays there they've become there's standards in use and There is now a common standard IEEE 802 dot 16 Referred to as Y max for point-to-point fixed wireless links Also and not so common, but also for a cheap solution 802 dot 11 wireless land can be used The purpose is to use as a replacement of point-to-point Wide area network links. So the best example is our link between two campuses We've got different options. We can pay a telecom company to use their wired network for example using pdh rent or lease from them a Digital circuit and use the wired network between our two campuses or unlike we have done we Can put an antenna on the top of this building and an antenna on top of a building at the other campus point them at each other and Using why max or a similar technology have a wireless link between two campuses And that's what we have in this case and of course our devices are fixed It's not to provide mobility and it needs to be configured in that the antennas have to be pointed in the right direction Why max as an example of a common technology used for this today provides speeds up to Around 70 megabits per second for that link with a point-to-point link The because the energy is focused in one direction usually interference is not a problem with It's hard to draw in two dimensions We have an antenna we have a point-to-point link The any with a directional antenna the energy of our signal is concentrated in this direction It doesn't go in this direction and it doesn't come out if you think in three dimensions from here And so therefore someone else nearby Can have another point-to-point link and it's unlikely that they'll interfere with each other okay, so It's easier to have multiple direct links and as a result get Higher speeds higher data rates Less like less likely for interference and having to share the spectrum So why max provides speeds up to for example 70 megabits per second. There's been some improvements to get higher speeds But usually that's over a range of Several or ten kilometers The alternative is to drop the speed use a lower speed and get a larger range of up to say 50 kilometers But with point-to-point fixed wireless links. We're normally talking about links that cover tens of kilometers and be further and Data rates in the order of tens of megabits per second and up. There are some using Unlicensed 2.4 gigahertz frequencies and some using specialized frequencies say 11 gigahertz Why max has a range of frequencies that are available? You can check set up a very cheap link Say from your home to your friend's home if you have No obstructions between your homes. Maybe you're out in the country somewhere by using simply Wi-Fi access points and Unscrew the antennas that come with it and you attach highly you attach directional antennas So these are omnidirectional and antennas if I can get it off You buy a different antenna one of those dish-shaped antenna and just attach it here put the dish-shaped antenna on the roof of your house Pointer at your friends and you can cover distance of several kilometers in that case with your normal Wi-Fi access point So in fact in special circumstances Wireless LAN can be used for fixed point-to-point links, but it's not so common It's used in case where we want to be very cheap We want a cheap solution. What does LOS mean? Line of sight it means between the transmitter and receiver. There are no obstructions If you stood at the transmitter, you'd be and you had perfect eyesight. You'd be able to see the receiver There's not a building in between. That's the general idea This is non line of sight. We may have obstructions in this case So in fact Y-max can be used in two different modes a point-to-point mode and a point-to-multi-point mode in Thailand for example to use Y-max or similar technologies, you need a license or special conditions for SIT to get the antenna on the top We had to go through months and months of processing to get the right license to to do that another technology satellite communications in the case where we do not have wired links We're too far away to provide point-to-point wireless links and satellite may be an option where we have a satellite up in space and We either have a point-to-point topology. We have some Station on the ground an earth station that transmits up to the satellite and that satellite transmits down to another earth station Point-to-point from this point to this point It's an option say for connecting from one country to another country the alternative is to use a Wired link between them or a wired network and use a submarine cables under underwater underground cables or a point-to-multi-point topology where We have a transmitter an earth station that transmits up to the satellite and then the satellite broadcast to everyone within range Everyone who's within the footprint of the satellite can receive the signal Satellite TV is the best example there the TV channel transmits the signal up to the satellite the satellite sends down everyone who has a receiver within range of that satellite can receive the transmission and The range of the satellite depends upon the orbit of the satellite. Okay, how far above earth it is So the lower it is or the lower the orbit the smaller the range in a Geo Geostationary orbit geosynchronous orbit It's provides a range of about covering a third of the earth So the range is in hundreds to thousands of kilometers We will not cover the details of how satellite links works just one other alternative one of the more popular Satellite internet service providers in Asia Pacific region is IP star using the tycom satellite the ty satellite For internet access TV radio broadcasting Telephone applications in in locations where there's no mobile phone service for example last one with which we want to talk about and Who will mention the the basics and then I'll give you a detailed example of some of the The commercial aspects of it is your mobile phone mobile telephony cellular communications where we have We have a base station Which plays a similar role to your access point in a wireless LAN network, but different technology We have a base station That transmits wirelessly to our mobile devices our mobile phones and Then from that base station It uses wide links normally out to the rest of the network and the rest of the internet who are the Main Telephone mobile telephone companies in Thailand companies organizations D-Tac Anyone else? I'm new here. I have only been here for a few years. Who else? true AIS They would be the main three. They may be smaller ones, but they are the main three mobile telephone operators in Thailand and then we have Somehow related the two Basically government organizations cat and to T who provide telecom services as well and there's a mix between them Also with mobile telephony mobile phones I'll go through some D or some some technical details and then I have a presentation that I've stolen from AIS That talks about the relationship between these companies for mobile phone access and Leads to 3g and and some of the issues there will go through that So of course mobile phones for voice communications But nowadays for internet access data communications as well, okay, and that's what we're focusing on on this topic and this this course about Internet technologies data communications Ranges in fact the range of mobile phone the base stations Differs depends upon where they're located, but they can be Hundreds of meters to several kilometers a few kilometers in distance in terms of standards used for mobile phones There have been two different paths taken in the world There's been one path taken mainly come from European standards and one from North American standards so in the past and You know the terminology Mobile phone standards and technologies have improved over time and the marketing Labels given to those improvements have been referred to different generations. Okay, so We have the first generation The second generation third generation fourth generation I'm thinking about the fifth 4g and People even talk about 5g the fifth the next generation Really, it's referring to a broad class of technologies Used where the first generation was really the old-style analog phones and They were bigger than this. Okay, so they were large large phones originally Used analog transmission 2g second generation moved to digital transmission and the The main one used was used a technology called GSM In North America, there was an alternative called CDM CDM a1 Had a few different names So there were two different standards and at some point you couldn't use your phone your GSM phone in the US for example but that's the the second generation technologies and Then people started to using them not just for voice calls, but for sending data traffic as well Okay, they use them for internet access and some of the These are some of the acronyms that refer to the technologies used for data access You don't have to remember them all you some of you already know some will talk about in more detail For GSM there was what was called circuit switch data Which was like using old-style dial-up modem, but using a mobile phone provided data rates are around And I think it says in one of the later slides here around 14 kilobits per second for data access circuit switch data and Then that was improved and there was gprs Which provided now I'll go to the next slide General packet radio service gprs, but the idea Was to use packet switching and send your data via packet switch network instead of a circuit switch network And we got data rates in the order of tens of kilobits per second These give typical data rates for the first one is downlink download and then upload So there were differences you could download faster than you could upload in most cases and then that was improved and The name of the improvement was enhanced data rates for GSM evolution edge So now we're talking about data rates of 100 200 kilobits per second download and both gprs and edge were extensions of GSM so GSM was a 2g Second-generation technology it was improved gprs and then edge Sometimes they're called what 2.5g They're not 3g 2.5g or even 2.9g in some cases That is they're not 3g, but they're improvements over the original second-generation technology will come to the others the 3g in a moment from the North American perspective there was a different technology CDMA one and Similar that had some improvements over time We're not going to cover them but similar similar Development you know where we use mobile phones for internet access today. I think there's not much to say about that what's the a Very simple view of the network topology for a mobile phone network Here you are These are the bus base stations and you see them you see the towers You see them on top of the buildings with different antennas Often the antennas are not necessarily a dish antennas, but sort of long long rectangles like this Long long antennas about this size and there might be multiple on a big tower on top of a building in that they're pointing in different Areas so they're sectorized There's an antenna pointing in this way another one and there may be multiple sectors that they provide coverage of So they are the base stations Okay, and the wireless link is only from your mobile phone to the base station typically those towers those base stations have some wired links and because Each base station may have a range of let's say several kilometers to provide coverage of the an entire city of all of Bangkok We need multiple base stations and to provide coverage of the entire country. We need hundreds thousands of base stations so we have network operator like DTAC true a is They build their build and locate their base stations throughout a city throughout the country and then connect them all together via their own network We say that the operators core network and that can be a complex network there. It may be covering the entire country Of course you use a mobile phone to make voice calls and the typical mode was that you connect to a base station your voice There's a circuit switch connection that goes through the network operators network and Goes to a gateway to the public telephone network the public switch telephone network PSTN And this is just the normal fixed telephone network That's for telephone calls. So when you make a call it goes to this gateway and then out to the telephone network But when you use your phone for internet access It goes through the network operators network and then to a gateway to the internet through to an internet service provider and it goes through their network to the whoever the destination is on the internet So there was a separation of the telephone network and the internet for data communications in recent improvements of Of the mobile telephone technologies in recent generations the idea is to combine them that is to make voice traffic to flow through the internet and Throw all of the voice traffic current or in the old style when you make a voice call there's a circuit switch connection to the gateway and then out to the telephone destination with the New approach they use packet switch connection. So basically you use voice over IP for your voice calls and Everything here. There's not two separate networks, but everything is treated as the one network here. It's all packets It's all data some may be voice some may be request for web pages whatever The idea is to treat all voice and data communications the same on the same network and That's more so in 4g fourth generation technologies is to combine them together and to all use internet technologies So that's the simple view of the topology of a mobile phone network The end users base stations, and then we have a network a wired network that connects them together with GSM The improvements to go up to gprs and edge We're relatively minor improvements for the technology in the network in the op-core network and on the base stations so They were extensions to GSM and To upgrade so let's consider a is that has base stations all across Thailand To upgrade from GSM to gf gprs and then to edge Required some minor upgrades in their network their core network and on the base stations. It didn't require Complete replacements of the base stations Okay, it didn't require completely new hardware mainly software upgrades So not so hard to upgrade but the next step Where these are two two and a half g up to 3g generally requires a major upgrade of Hardware at the base stations especially Because they're using different Transmitters and and different frequencies So the next step from 2g up to 3g is a new system compared to GSM and 3g requires a major investment from the company to upgrade their network One of the standards for 3g communications is called umts universal mobile telecom system and There've been some variants as well. So there are different standards for 3g and in terms of data rates originally talking about 380 kilobits per second For data access, but since umts has been released. They've been improvements and and further improvements and First there was what's called high speed Downlink packet access high speed packet access the general acronym or the general name and there was one Improvement to improve the speed of downlink downloads and one to improve going from mobile phone to base station uplink So we get high speed downlink packet access Provided data rates on the downlink of up to 14 megabits per second and Then high speed uplink packet access so upload around up to about six megabits per second And then further improvements were available called HSPA plus which was both uplink and download Talking about 42 megabits per second down 22 megabits per second uplink. So that's from your mobile phone So that's that's still considered 3g technologies They are again improvements or enhancements of the original UMTS and And Generally not too hard to upgrade if you've got a UMTS original base station to upgrade up to HSPA plus Using similar technologies just mainly software upgrades the next step up In some cases called fourth generation 4g is another major upgrade to called long-term evolution LTE So a new system again, so from a company's perspective a large investment to move from UMTS and hates SPA up to LTE So takes more time to do that Where are we today? What's the fastest you can download via mobile phone anyone? Anyone done any tests? 3g yeah And we'll talk about the company shortly, but what about speeds is anyone noticed or measured any speeds for downloads? some some companies would advertise I think in the order of 14 megabits per second for So I think true supports 14 megabits per second HS DPA. I'm not sure maybe more recently has moved up as well So different companies any not just in their entire network in different base stations or different areas They may have support for the newer Technologies here in the in some areas. They may be limited to the low rates some areas. They don't have 3g and you drop back to edge or gprs So it depends upon where they've deployed the technology in their network But we see and in a number of countries this is common HS PA plus So we're seeing data rates Similar to and greater than wired technologies like ADSL But this is your normally shared That is the more users Accessing a base station The less you will get So it's not dedicated for you it depends upon the operations of the company as to what speed you will get but normally it's a shared medium in that If there are many people connected to the one base station the data rate You're going to get is going to be much lower Then but if there's no one connected then you may get high download speeds. So that's one of the limitations that we have whereas with For example, if you want fast internet access at home, what have you got as a choice? All right, if you've got a telephone cable you can use ADSL up to 24 megabits per second in theory Or you could use your mobile phone for home internet access In theory up to 42 megawatts per second down but That may vary depending upon the other users in in the vicinity And in the future or even available in some some countries. We're talking about closer to hundreds of megabits per second download speeds I'll return. I'll come back to the companies with but let's just present the summary here where we switched to that So with wireless networks Can be used in both access networks where the end user connects to the network wireless LAN your mobile phone and also in core networks in fixed fixed point-to-point wireless networks of wireless links and Also satellite can be used in core networks For in the access point the purpose mainly is to provide mobility in the core network is to Act as a replacement of cables generally Comparing wireless to wired technologies For the same costs wired technologies are faster than wireless Some rough comparisons shown here. Okay inside your LAN At the same cost or approximately the same wireless LAN 54 maybe 100 megabits per second but shared Ethernet 100 1000 megabits per second home in 2g talking about hundreds of kilobits per second with mobile phone up to several megabits per second with old ADSL and even with 3g you're talking about maybe 10 megabits per second up to 24 megabits per second and Even if you've got high-speed packet access Compared to say optical fiber to a building is a significant difference in speeds So generally wired technologies are faster than wireless technologies for similar cost There may be some exceptions there. Of course wireless technologies often provide us convenience and mobility The next I'm going to show you something you don't have a presentation. I've just downloaded from a website. It's just it's good to give some examples But any questions about mobile phones You all know how to use them We will not cover the the protocols and the standards behind that behind them, but it's nice to know Be aware of some of the terminology and some of the standards First some pictures And again, these are from websites. No need to to copy this down. We'll see this one later When we look at wireless land in details This is the wireless land standards that have been developed over time 802.11 is the name of the standard and it's a physical layer standard. How do we transmit our? bits as signals as wireless signals and It's been improved over time. So the original standard was in 1997 802.11 the frequency band was the 2.4 gigahertz one we've mentioned and the signal bandwidth was 20 megahertz and originally a data rate a maximum data rate of 2 megabits per second, but Even as that was released they were working on improvements both 11a and b 11b was a popular one that provided 11 megabits per second and an improvement in 2003 release was 11g Up to 54 megabits per second Nowadays most devices you buy new support 11n up to in some special cases 600 megabits per second but You see it uses what advanced advanced antenna and technologies multiple input multiple output Rather than transmitting with just one antenna you may see access points with right two three or even four antennas and They use some advanced technologies to receive the signal of multiple antennas to speed up the data transmission but higher cost involved and their improvements Expected in this next year and maybe the subsequent year for the very special cases talking about gigabits around seven gigabits per second But using completely different frequencies and will cover very different scenarios Not so much for covering a room or a building but for very short distance communications like Monitor to PC for wireless video This one and again, there's a link to the website from our course website that covers contains this picture It shows the evolution of the 3g or that the mobile communication standards So to 2g here GSM In North America, they had CDMA one and there was also TDMA and in Japan and Korea They had something called PDC and That was improved to provide higher data rates gprs for example Then 3g wideband CDMA Also called UMTS Edge fits in there in this diagram and then the improvements here of high speed downlink packet access high speed uplink packet access called sometimes three and a half g 3.5 High speed packet access plus 3.9g it depends upon the company's what they actually call it. It's more a marketing term and Long-term evolution and there's long-term evolution advanced even here and similar developments Wi-Fi wireless LAN has improved over time at about the same times 11n Also, there's Wi-max which has been improved for mobile Wi-max and Wi-max 2 and We in the future will have 802.11ac and AD for wireless LAN standards So as it says here increasing efficiency bandwidth and data rates are faster better performing technologies over time And this is the same or similar information just a different different picture different perspective showing focusing on 3g and Moving towards 4g long-term evolution. We're talking about data rates in the order of hundreds of megabits per second Tens of megabits per second per user And in the future maybe Up to 100 megabits per second per user download for example in the last 10 minutes Let's look what AIS to say about themselves. This is that one of their promotional presentations I found on their website it's useful because it gives some some statistics and some examples of their network and also some issues about the Relationship between the companies for mobile communications in Thailand Because you know there are several companies that provides a service and you probably also know that there's this 3g auction last month And that's been a long time coming and different issues involved. We'll see some of these slides here Just an example. You don't have to remember this We'll see the relationship between the companies. I'll skip over some slides This is from August this year. So it's quite recent. So it talks about the mobile phone penetration in Thailand 114 percent. What does that mean? Someone has more than one phone that is in a population of 68 million people There are what around 80 million phones or or subscribers or not necessary subscribers phones So people have more than one phone. Some people don't have a phone. Some have more than one or multiple phones What else does it show? So this maybe this plot shows subscribers in Thailand So in terms of millions up to 78 million and penetration rate Here subscribers market share between the three companies DTAC true and AIS here TMV means true move But true in this case So AIS 45 percent True 25 DTAC around 30 percent. So the three main operators in Thailand And similar based upon market share or revenue How much money they bring in? This one is Tries to illustrate the relationship between the government organizations and the the commercial operators And it's quite complex. So and I do not understand the details, but we'll see what we can pick up from here. There are It's what's now called MBTC What is it the National Broadcasting and Telecommunications Commission? so a government organization or set up by the government for managing communications and broadcasting inside Thailand allocating frequencies to organizations and So the services can be provided. So not just mobile phones, but also landline and TV Broadcasting and radio as well and Then there's the two what were Well, our primary government organization TOT and cat. Okay order. So they have been around for a long time So providing telecommunications and cable Communications throughout the country. So they have networks built through the the country wired networks and Then you have the commercial operators And this is not just for wireless, but also wired so the ones we're focusing on AIS DTAC true move and there's others for fixed line for home phone connections and The way that it's worked is that The these organizations pay some license they get the license for the frequencies and then these commercial organizations get What it's called here a BTO contract a bill transfer operate what they do is that TOT has the license for the mobile phone Frequencies not at 2.4, but the different frequencies used for mobile phone networks But then AIS or the others they get a contract to build the network and So they build the network for TOT and Transfer the ownership of that network to TOT, but then operate it for them so AIS builds a network and then opera operates that network on behalf of TOT because TOT has the license to use it not AIS So then when AIS makes money People the customers pay AIS Then a percentage of that money goes to TOT because TOT has the license so that's the how it's operated in the past It's slightly different, but that's the main way that the mobile phone networks operate Some are to TOT TOT summer to cat This gives a little bit of information about the frequencies NTC was the old organization before NBTC and this is some special case frequencies Which are allocated for originally for trialing 3g networks for doing test networks For not to cover the entire country, but to in cut to cover some areas So we can see some examples here TOT had a license for a 900 megahertz mobile phone network and Also a 2.1 gigahertz mobile phone network and in the world The most commonly used frequency from 3g is this one 2100 megahertz 2.1 gigahertz all mobile phones 3g mobile phones almost all of them will support this frequency Not all of them will support the other frequencies like the 900 megahertz and the 850 megahertz In different countries it varies, but the most common one is the 2.1 gigahertz So TOT had a license to have two networks or using two different range of frequencies One of them AIS had the contract to build a network and to operate that so in the 900 megahertz similar the cat 850 megahertz and who had that DTAC and and true had a contract to build that network and Operator on behalf of cat at the 850 megahertz Most of you who have 3g access will be using one of those two networks in fact sometimes when you buy a mobile phone You it's specified you can choose between the AIS version and the true version or DTAC version Because the mobile phone may only operate on one of these two frequencies Most 3g phones will operate on the 2.1 gigahertz But not all will operate on 2.1 plus 900 megahertz and 850 megahertz Some will only operate on 850 or 900 So that's when you choose You are stuck with one You cannot necessarily use that phone on another operator And that's the problem of some of these networks that because not everyone uses it You cannot easily move to other networks TOT also had a license all has a license for the 2.1 gigahertz the popular one and what they did is they Contracted out to other smaller companies Who I mobile I think had one contract and a few smaller companies called mobile virtual net network operators they TOT had the network and they just Use their network these smaller companies use the network and sold the service to us and users customers but that network of the 2.1 gigahertz didn't provide as much coverage as the ones built by AIS true and DTAC and They the frequencies that they are allowed to use we can see the bandwidth available 17.5 megahertz 75 megahertz here 25 and different frequent bandwidths available to each organization So it's a complex relationship between Accessing those licenses and between the different country companies So this concept of TOT has the license and then AIS goes to them and Builds the network and then operates it and all the money AIS gets they pay a percentage to TOT how much a revenue share of Between 20 and 30 percent So everything you pay AIS 20 percent or up to 30 percent goes to TOT plus some other Some other other charges and similar DTAC and true pay cat around 30 percent so of their income they pay to use that license The idea then with this 3g auction was to license different frequent or different Channels or different right bandwidths in the 2.1 gigahertz frequency range and To auction as you know auction to these three companies eventually DTAC true and AIS So they could build their own network They get the direct license. They don't get the license through someone else as a result They pay for that license and no longer have to pay TOT and cat the revenue share so the idea from These companies perspective is to reduce this to lower their costs and that's Shown here the idea was at this this license which was recent in the 3g auction last month that they have to pay some Percentage of their revenue and it turns out to be a license fee of two percent plus some Other other fee for universal service of three point seven five percent So around less than six percent that they pay as opposed to twenty or thirty percent That's the benefit for AIS DTAC and true They pay much less to someone else to use that mobile phone license And that's why they wanted this auction to go ahead That's I think the main things that we can pick up from here. There's a few other details Okay, they road map but again we see their road map includes supporting HSPA plus long-term evolution for AIS and Network topology, which is similar to what I showed but a little bit more complex, but we have base stations switching centers are base stations mobile phones and this is the core network and These are the gateways for the voice and the data Gateway to the telephone and to the internet and I think that's all from there. The rest is about the company Okay, so just an example at least in Thailand that the mobile phone The operators and the licenses is a complex thing But very important because it will provide Higher data rate services in the future for all of us Tomorrow we'll move on to the next topic about very basics of the internet and then a few new things about the structure of the internet Let's continue then