LTE Network Architecture Overview

hello in this section we will give you a quick overview of the network architecture and lte uh the understanding of the network architecture is uh is very important for us to understand all the features that are going to be covered in lte advanced nlt advanced pro so let&#39;s jump right in on a high level um the network architecture in lte is composed of two parts you have the eu tran or the radio access network uh here uh represented by this uh oval shape and then you have the evolved packet code which is called epc where represented here and there is bi-directional communication between each of them between both of them actually and the radio access network is the piece of the network that directly interacts with a user uh equipment or ue as it&#39;s called in lte terminology and all the um all the traffic for that particular user goes to the ran and then is passed on to the epc out to wherever application the user intends to access we will add a lot more detail into each of these boxes in the next couple of slides so here uh we have put down the architecture of lte in a lot more detail here so there are the two boxes that we talked about in the previous slide you have the eu tran or the radio access network and then you have the evolved packet core or the epc within the eu tran as you can see you have multiple e node b&#39;s that are able to talk to each other by the x2 interface again this x2 interface is the interface that is used by enough bees to talk to each other and share signaling and control plane messages uh and also user plane data traffic as we will see with some of these new features uh the e note b directly connects uh to a user equipment or a mobile phone or lte terminal however you want to call it and uh all the communication happens over the uu interface which is the name of the interface or the link on the air interface side and then you have the e node b that talks to your mme or the mobility management entity over the s1c protocol and well actually s1ap protocol but on the s1c interface the mme in turn talks to the hss over diameter protocol using a diameter as a protocol and then this interface is called the s6a interface the mme is also responsible for talking to the s11 interface which connects to the serving gateway and the serving gateway interacts with the packet gateway via the s5 interface the e node b and the s gateway are connected by the s1u interface and the p gateway connects to the external network in this case it&#39;s the internet by the sgi interface so one quick uh thing to point out is you probably noticed that there some of these arrows are solid like here whereas some of these are broken arrows as is depicted in this legend and the reason for that is all these solid arrows actually depict the user plane interfaces whereas you can have you have on the broken arrows you have control plane signaling happening with the exception of here x2 where you can have both you can have both control plane and user plane riding on this interface so just keep in that keep that in mind i&#39;m sure this picture is already familiar to you based on other lte courses you have taken but just wanted to refresh your concepts regarding the architecture let&#39;s take a little deeper dive into each of these boxes starting off with the utran where utran has the e node b&#39;s and the e node b&#39;s are responsible for the following functions here radio resource management so managing these spectrum resources is the responsibility of the node b and the e note b does that by you know it has a something that&#39;s called a scheduler and that scheduler as more and more users come in uh it is able to schedule these resources and thereby perform the radio resource management if you also uh want the not be to take care of all the synchronization and interference control by talking to the other renowned bees as well as scheduling different users within that given a node b so that they don&#39;t interfere with each other or interfere at the bare minimum the e note b is also responsible for selecting the mme from either a pool of mmes or a given mme if there is only one then it&#39;s simple it&#39;s a one-to-one relationship but you can have multiple mmes in which case there is a one-to-one relationship between the e note b and the mme technically speaking there is a sctp association stream control transmission point uh association between eg node b and um mme so in case there are multiple mmes uh enode b is also responsible for routing of user plane traffic uh to and from the serving gateway so you have this solid arrow here and you route all the traffic for that given user to the serving gateway and from the serving gateway back to the user depending on if it&#39;s uplink or downlink the mme is also responsible for encryption and integrity protection of user data so encryption and integrity are two specific and different concepts encryption is where you ensure that this uh the data is not compromised nobody can can sniff and you do that by using some security keys and integrity protection is where you have a means of making sure that the data that you transmitted is actually the data that&#39;s received and you do that using a certain concepts in in lte related to ack and knack and those kind of things and those again happen at the end b level and ib header compression is where you perform ip header compression to increase your network capacity and increase your link budget in certain cases of poor poor coverage so continuing with our discussion on the rant side in the ran we use ofdm which is called orthogonal frequency division multiple access technique in the downlink here you have the node b you have the ue and we just show that the this is the multiple access technique used in downlink and the reason we do that we use ofdma is because of some of these advantages that it has it is very highly spectrally efficient since you have multiple sub carriers and you can modulate each of those subcarriers you are able to squeeze in a lot of data uh given uh your ofdm subcarriers that&#39;s why it&#39;s highly spectral efficient compared to some of the other multiple access techniques uh it&#39;s very robust to multipath because your symbol your in frequency domain you have very narrow subcarriers which translate into a higher spread in the time domain therefore your render symbol interference is likely not going to be an issue because of a high symbol time so that&#39;s why it&#39;s a robust against multipath there is inherent support for mimo in ofdma it&#39;s it&#39;s very easy to implement given that you have multiple subcarriers you can send each of these subcarriers across different streams and thereby implement mimo in in in a lot more easy fashion so um we also have a time and frequency allocation flexibility that is also offered by ofdma because you have these sub carriers and these subcarriers are in the frequency domain but you can also schedule users on the same subscribe sub carrier as long as they are at two different time slots so there is another dimension here where you are able to allocate resources in both time and frequency domain that&#39;s a very big advantage of ofdma on the uplink side we use sc fdma so a reason for that is there&#39;s a major challenge with ofdm and that is because of high peak to average power ratio of the transmitted signal and this is a consequence of the ifft summing of multiple independent symbols which are all uh integral number of a cycle over a simple time and whenever we don&#39;t do that they constructively add uh and there&#39;s a very high power and because of that high power the the design of the ue um uh uh transmitter would get a lot more complicated so in order to overcome that we use uh sc fdma but uh here uh this also has high power peak to average power ratio but we overcome that uh into a lot extent by actually transmitting symbols in sequential rather than parallel there is one downside here the downside being your throughputs are not as high as what you would see in downlink so your upping throughputs are typically very low compared to the downlink they are still very high but they are not as high as downlink and part of the reason is how this processing happens in the sc fdma but actually it has more benefits in the sense that we get a better cell edge performance due to a relatively low peak to average power ratio compared to an ofdm so you&#39;re you&#39;re you&#39;re able to maintain a decent level of synar even though you are a little farther from the site from your node b so that&#39;s one advantage of sc ftma so now let&#39;s examine ofdma in a little more detail so that we get a better understanding so there exists obviously several multiple access techniques in wireless communications you have tdma where you divide all your channel in time slots and you allocate your entire frequency to a given user across different time slots so you have the frequency here on the y-axis and you have time so you are allocating the same frequency but across different time slots now you have fdma where you chop up your frequency in multiple chunks and you allocate all your users each of those chunks but across the entire time and then you have ofdma where it gets a lot more complex where you have frequency chunks and you have time chunks and then you kind of multiplex your user so that different users use different mul frequency chunks across different times or if they want to use same chunks of spectrum they use at least at different times so now this is uh this is illustrated here and then of course you have cdma which is a very robust technique where you use some sort of coding to uh to uh do some sort of spread spectrum uh stuff uh on the transmit signal and therefore they don&#39;t interfere with each other and these codes are kind of orthogonal so that&#39;s one another multiple access techniques but the choice that has been adopted in lte is the ofdma the ofdma is not new and has existed for quite some time actually you may be familiar with wi-fi being using ofdm for quite some time now uh the idea is to divide entire bandwidth into chunks called subcarriers and these subcarriers can then be allocated in time and frequency domain the neat part about subcarriers are they are orthogonal in nature so you have these subcarriers are shown here across on the frequency domain and their nulls coincide with the peaks of their neighboring subcarriers as a result of which the interference between each of them is very minimal calling them orthogonal so that&#39;s where the orthogonal comes in here&#39;s another picture where you have multiple subcarriers here in the frequency domain this is shown for a five megahertz bandwidth and then once you do a frequency or sorry a fast fourier transform to go to a time domain you can convert all these and time domain symbols which can be transmitted so that&#39;s how you switch between frequency and time domain lte provides these modulation schemes in addition you have the 256 comm that&#39;s not mentioned here but that is again a part of lte advanced and cyclic prefix is this black region that you see that is added uh to prevent uh from inter-symbol interference uh wherever it exists and it actually has you can have a normal cyclic prefix and extended cyclic prefix depending on your cell range and there is a 15 kilohertz subcarrier spacing so each of these sub carriers differs by 15 kilohertz or are spaced 15 kilohertz which translates into a simple time or a simple duration and then of course we talked about the scalable bandwidth as defined in 3gpp where you can support 1.4 3 5 10 15 20 depending on how much spectrum you own so carrying on with ofdma just some background in lte transmission happens every one millisecond which is called a transmit time interval so you have you can think of it like in time domain as this where you have one radio frame which is 10 milliseconds and then that radio frame is actually divided into 10 subframes where each subframe is one millisecond which is the amount which is the transport time interval which that is a data is transferred to you is once every millisecond and then one within one subframe you have two slots we have slot one slot zero each slot is 0.5 milliseconds and then within each slot if you look at this picture here you have some ofdm symbols and they can be from 6 to 7 in this case there are 1 2 3 4 5 6 7 of dm symbols and the reason it changes from 6 to 7 is because depending on whether you are using a extended cyclic prefix or a normal when you use normal you have seven over fdm symbols when you have an extended you decrease the amount of symbols so you sacrifice some data rate but you transmit six ofdm symbols per per slot hopefully this is clear to you where the the the division of a radio frame into sub frames and slots here&#39;s a picture this will be the last picture on the the rand side just for the architecture point of view so just to reiterate you have a frequency domain here on this axis you have time domain on this axis and you have these sub carriers that are available to you uh the number of subcarriers depends of course on the bandwidth that you have but there is a subcarrier spacing of 15 kilohertz that is standard in lte and then one resource block um so before we get talking to resource blocks actually let&#39;s then we have one slot of 0.5 milliseconds that we looked at before we have seven of dm symbols within that we have one subframe which is one millisecond and each subframe is composed of two slots so one this one and the other one this now we also have a concept of called resource blocks and resource blocks in a sense refers to a chunk of 12 sub carriers across one millisecond so if you look at this you will have 12 sub carriers here across one second is called one resource block pair and this is the minimum allocation that you can give to a user so you can see you can allocate more than one resource block that&#39;s not an issue but you at the minimum you have to allocate it if there is a request from a ue at the minimum you have to allocate it one resource block pair and then using ofdma you can obviously schedule your users to use different chunks of spectrum across different times so this is a great overview of how spectrum is allocated so this this finishes our network architecture overview of the ran and next we will talk about the epc so here we have we have covered all the topics in this you ran in fairly good amount of detail and hopefully you have a good understanding and a refresher of the utran architecture next we&#39;ll start with the epc first we&#39;ll talk about the mobile led management entity which is right here uh the mobility management entity is responsible for all the nas signaling and its security so nas is all the control plane signaling between the ue and the mme it is responsible for tracking areas list management so you can have multiple tracking areas as part of your ran the management of these lists is done by the mme mme is also responsible for all the gateway selection so it selects which gateway a user is uh connecting to and also which uh so and the gate gateways can obviously be serving and packet they are responsible for all the roaming and authentication so the the mme is responsible for communicating with the hss to authenticate a subscriber so to make sure that the subscriber is legit uh it is also responsible for all the eps better management so evolved packet system is eps better management is better it just refers to a connection between the ue and the network and all the better tear up tear down is handled by the mme so the mme is kind of the controller it knows what to do for a given user when to bring up a bearer when to bring it down and all that kind of stuff it also handles the signaling for mobility management between 3gpp rams so you can have a utran umts network that is alongside your eu tran and the user may move in and out and you may want to want the user to hand over across these different networks so the way you can do that is by letting your mme control all that signaling so the mme would talk to the msc that is handling your utran network and would manage all the signaling in that case the good news is with lte advance and lte advance pro nothing has changed actually on the epcps uh i just wanted to give you a good overview of the different network elements before we delve deeper uh but the all the changes that we&#39;ll be talking about are happening in this box so if you still have some doubts i would recommend doing some more reading on the utran before you go any further here the network architecture is uh defined you know the same picture that we have looked at so far but i have added some functions for each of the network elements here you may want to just take a look and if you have any doubts you know just you may want to search for these before going any further so another key concept that we need to make sure we understand is the concept of bearers so you have the ue on one side and you have the other network on the other side in this case uh it is the internet and you have what is called an end to end service better this service better traverses uh your utran epc and all the way to the internet this actually is composed of your eps bearer and an external bearer the eps bearer is composed of a eu-tran radio access bearer which is the bearer or the connection between the ue and the e node b and the s5s8 bearer which is the serving gateway to the p gateway bearer and the srb drb is the better or the connection between the ue and the e node b and then you have the s1 bearer which is the e node b to the serving gateway each of these bearers depending on what kind of traffic they carry they can have a different quality of service requirement which we&#39;ll look at in the next slide so yep so ltqos that we have talked about it can be a default bearer or it can be dedicated better a default bearer can uh only be a non-gbr gbr meaning a guaranteed bit rate so non-guaranteed bit rate there is no quality of service essentially and dedicated bearer can be a gbr or guaranteed bitrate error or a non-gbr and these are the attributes that each of these bearer types have a non-gbr can mostly be only qci-9 and these bearers will have certain attributes gbr is mostly qci 1 through 4 and it has these attributes so let&#39;s look at what qci means qci is quality of class quality service class indicator and each of the qci has certain [Music] attributes that need to be met at the bare minimum so for example qci1 is a guaranteed bitrate bearer with the priority number two with a packet delay budget of 100 milliseconds at all allowed packet loss is 10 and an example service that may use qci one is a voip call or a volte call so so this wraps up our architecture overview uh i hope you have refreshed all the architecture concepts in lte and next we will start talking about the lte advanced features in the next section so see you in the next section you

hello in this section we will give you a quick overview of the network architecture and lte uh the understanding of the network architecture is uh is very important for us to understand all the features that are going to be covered in lte advanced nlt advanced pro so let&amp;#39;s jump right in on a high level um the network architecture in lte is composed of two parts you have the eu tran or the radio access network uh here uh represented by this uh oval shape and then you have the evolved packet code which is called epc where represented here and there is bi-directional communication between each of them between both of them actually and the radio access network is the piece of the network that directly interacts with a user uh equipment or ue as it&amp;#39;s called in lte terminology and all the um all the traffic for that particular user goes to the ran and then is passed on to the epc out to wherever application the user intends to access we will add a lot more detail into each of these boxes in the next couple of slides so here uh we have put down the architecture of lte in a lot more detail here so there are the two boxes that we talked about in the previous slide you have the eu tran or the radio access network and then you have the evolved packet core or the epc within the eu tran as you can see you have multiple e node b&amp;#39;s that are able to talk to each other by the x2 interface again this x2 interface is the interface that is used by enough bees to talk to each other and share signaling and control plane messages uh and also user plane data traffic as we will see with some of these new features uh the e note b directly connects uh to a user equipment or a mobile phone or lte terminal however you want to call it and uh all the communication happens over the uu interface which is the name of the interface or the link on the air interface side and then you have the e node b that talks to your mme or the mobility management entity over the s1c protocol and well actually s1ap protocol but on the s1c interface the mme in turn talks to the hss over diameter protocol using a diameter as a protocol and then this interface is called the s6a interface the mme is also responsible for talking to the s11 interface which connects to the serving gateway and the serving gateway interacts with the packet gateway via the s5 interface the e node b and the s gateway are connected by the s1u interface and the p gateway connects to the external network in this case it&amp;#39;s the internet by the sgi interface so one quick uh thing to point out is you probably noticed that there some of these arrows are solid like here whereas some of these are broken arrows as is depicted in this legend and the reason for that is all these solid arrows actually depict the user plane interfaces whereas you can have you have on the broken arrows you have control plane signaling happening with the exception of here x2 where you can have both you can have both control plane and user plane riding on this interface so just keep in that keep that in mind i&amp;#39;m sure this picture is already familiar to you based on other lte courses you have taken but just wanted to refresh your concepts regarding the architecture let&amp;#39;s take a little deeper dive into each of these boxes starting off with the utran where utran has the e node b&amp;#39;s and the e node b&amp;#39;s are responsible for the following functions here radio resource management so managing these spectrum resources is the responsibility of the node b and the e note b does that by you know it has a something that&amp;#39;s called a scheduler and that scheduler as more and more users come in uh it is able to schedule these resources and thereby perform the radio resource management if you also uh want the not be to take care of all the synchronization and interference control by talking to the other renowned bees as well as scheduling different users within that given a node b so that they don&amp;#39;t interfere with each other or interfere at the bare minimum the e note b is also responsible for selecting the mme from either a pool of mmes or a given mme if there is only one then it&amp;#39;s simple it&amp;#39;s a one-to-one relationship but you can have multiple mmes in which case there is a one-to-one relationship between the e note b and the mme technically speaking there is a sctp association stream control transmission point uh association between eg node b and um mme so in case there are multiple mmes uh enode b is also responsible for routing of user plane traffic uh to and from the serving gateway so you have this solid arrow here and you route all the traffic for that given user to the serving gateway and from the serving gateway back to the user depending on if it&amp;#39;s uplink or downlink the mme is also responsible for encryption and integrity protection of user data so encryption and integrity are two specific and different concepts encryption is where you ensure that this uh the data is not compromised nobody can can sniff and you do that by using some security keys and integrity protection is where you have a means of making sure that the data that you transmitted is actually the data that&amp;#39;s received and you do that using a certain concepts in in lte related to ack and knack and those kind of things and those again happen at the end b level and ib header compression is where you perform ip header compression to increase your network capacity and increase your link budget in certain cases of poor poor coverage so continuing with our discussion on the rant side in the ran we use ofdm which is called orthogonal frequency division multiple access technique in the downlink here you have the node b you have the ue and we just show that the this is the multiple access technique used in downlink and the reason we do that we use ofdma is because of some of these advantages that it has it is very highly spectrally efficient since you have multiple sub carriers and you can modulate each of those subcarriers you are able to squeeze in a lot of data uh given uh your ofdm subcarriers that&amp;#39;s why it&amp;#39;s highly spectral efficient compared to some of the other multiple access techniques uh it&amp;#39;s very robust to multipath because your symbol your in frequency domain you have very narrow subcarriers which translate into a higher spread in the time domain therefore your render symbol interference is likely not going to be an issue because of a high symbol time so that&amp;#39;s why it&amp;#39;s a robust against multipath there is inherent support for mimo in ofdma it&amp;#39;s it&amp;#39;s very easy to implement given that you have multiple subcarriers you can send each of these subcarriers across different streams and thereby implement mimo in in in a lot more easy fashion so um we also have a time and frequency allocation flexibility that is also offered by ofdma because you have these sub carriers and these subcarriers are in the frequency domain but you can also schedule users on the same subscribe sub carrier as long as they are at two different time slots so there is another dimension here where you are able to allocate resources in both time and frequency domain that&amp;#39;s a very big advantage of ofdma on the uplink side we use sc fdma so a reason for that is there&amp;#39;s a major challenge with ofdm and that is because of high peak to average power ratio of the transmitted signal and this is a consequence of the ifft summing of multiple independent symbols which are all uh integral number of a cycle over a simple time and whenever we don&amp;#39;t do that they constructively add uh and there&amp;#39;s a very high power and because of that high power the the design of the ue um uh uh transmitter would get a lot more complicated so in order to overcome that we use uh sc fdma but uh here uh this also has high power peak to average power ratio but we overcome that uh into a lot extent by actually transmitting symbols in sequential rather than parallel there is one downside here the downside being your throughputs are not as high as what you would see in downlink so your upping throughputs are typically very low compared to the downlink they are still very high but they are not as high as downlink and part of the reason is how this processing happens in the sc fdma but actually it has more benefits in the sense that we get a better cell edge performance due to a relatively low peak to average power ratio compared to an ofdm so you&amp;#39;re you&amp;#39;re you&amp;#39;re able to maintain a decent level of synar even though you are a little farther from the site from your node b so that&amp;#39;s one advantage of sc ftma so now let&amp;#39;s examine ofdma in a little more detail so that we get a better understanding so there exists obviously several multiple access techniques in wireless communications you have tdma where you divide all your channel in time slots and you allocate your entire frequency to a given user across different time slots so you have the frequency here on the y-axis and you have time so you are allocating the same frequency but across different time slots now you have fdma where you chop up your frequency in multiple chunks and you allocate all your users each of those chunks but across the entire time and then you have ofdma where it gets a lot more complex where you have frequency chunks and you have time chunks and then you kind of multiplex your user so that different users use different mul frequency chunks across different times or if they want to use same chunks of spectrum they use at least at different times so now this is uh this is illustrated here and then of course you have cdma which is a very robust technique where you use some sort of coding to uh to uh do some sort of spread spectrum uh stuff uh on the transmit signal and therefore they don&amp;#39;t interfere with each other and these codes are kind of orthogonal so that&amp;#39;s one another multiple access techniques but the choice that has been adopted in lte is the ofdma the ofdma is not new and has existed for quite some time actually you may be familiar with wi-fi being using ofdm for quite some time now uh the idea is to divide entire bandwidth into chunks called subcarriers and these subcarriers can then be allocated in time and frequency domain the neat part about subcarriers are they are orthogonal in nature so you have these subcarriers are shown here across on the frequency domain and their nulls coincide with the peaks of their neighboring subcarriers as a result of which the interference between each of them is very minimal calling them orthogonal so that&amp;#39;s where the orthogonal comes in here&amp;#39;s another picture where you have multiple subcarriers here in the frequency domain this is shown for a five megahertz bandwidth and then once you do a frequency or sorry a fast fourier transform to go to a time domain you can convert all these and time domain symbols which can be transmitted so that&amp;#39;s how you switch between frequency and time domain lte provides these modulation schemes in addition you have the 256 comm that&amp;#39;s not mentioned here but that is again a part of lte advanced and cyclic prefix is this black region that you see that is added uh to prevent uh from inter-symbol interference uh wherever it exists and it actually has you can have a normal cyclic prefix and extended cyclic prefix depending on your cell range and there is a 15 kilohertz subcarrier spacing so each of these sub carriers differs by 15 kilohertz or are spaced 15 kilohertz which translates into a simple time or a simple duration and then of course we talked about the scalable bandwidth as defined in 3gpp where you can support 1.4 3 5 10 15 20 depending on how much spectrum you own so carrying on with ofdma just some background in lte transmission happens every one millisecond which is called a transmit time interval so you have you can think of it like in time domain as this where you have one radio frame which is 10 milliseconds and then that radio frame is actually divided into 10 subframes where each subframe is one millisecond which is the amount which is the transport time interval which that is a data is transferred to you is once every millisecond and then one within one subframe you have two slots we have slot one slot zero each slot is 0.5 milliseconds and then within each slot if you look at this picture here you have some ofdm symbols and they can be from 6 to 7 in this case there are 1 2 3 4 5 6 7 of dm symbols and the reason it changes from 6 to 7 is because depending on whether you are using a extended cyclic prefix or a normal when you use normal you have seven over fdm symbols when you have an extended you decrease the amount of symbols so you sacrifice some data rate but you transmit six ofdm symbols per per slot hopefully this is clear to you where the the the division of a radio frame into sub frames and slots here&amp;#39;s a picture this will be the last picture on the the rand side just for the architecture point of view so just to reiterate you have a frequency domain here on this axis you have time domain on this axis and you have these sub carriers that are available to you uh the number of subcarriers depends of course on the bandwidth that you have but there is a subcarrier spacing of 15 kilohertz that is standard in lte and then one resource block um so before we get talking to resource blocks actually let&amp;#39;s then we have one slot of 0.5 milliseconds that we looked at before we have seven of dm symbols within that we have one subframe which is one millisecond and each subframe is composed of two slots so one this one and the other one this now we also have a concept of called resource blocks and resource blocks in a sense refers to a chunk of 12 sub carriers across one millisecond so if you look at this you will have 12 sub carriers here across one second is called one resource block pair and this is the minimum allocation that you can give to a user so you can see you can allocate more than one resource block that&amp;#39;s not an issue but you at the minimum you have to allocate it if there is a request from a ue at the minimum you have to allocate it one resource block pair and then using ofdma you can obviously schedule your users to use different chunks of spectrum across different times so this is a great overview of how spectrum is allocated so this this finishes our network architecture overview of the ran and next we will talk about the epc so here we have we have covered all the topics in this you ran in fairly good amount of detail and hopefully you have a good understanding and a refresher of the utran architecture next we&amp;#39;ll start with the epc first we&amp;#39;ll talk about the mobile led management entity which is right here uh the mobility management entity is responsible for all the nas signaling and its security so nas is all the control plane signaling between the ue and the mme it is responsible for tracking areas list management so you can have multiple tracking areas as part of your ran the management of these lists is done by the mme mme is also responsible for all the gateway selection so it selects which gateway a user is uh connecting to and also which uh so and the gate gateways can obviously be serving and packet they are responsible for all the roaming and authentication so the the mme is responsible for communicating with the hss to authenticate a subscriber so to make sure that the subscriber is legit uh it is also responsible for all the eps better management so evolved packet system is eps better management is better it just refers to a connection between the ue and the network and all the better tear up tear down is handled by the mme so the mme is kind of the controller it knows what to do for a given user when to bring up a bearer when to bring it down and all that kind of stuff it also handles the signaling for mobility management between 3gpp rams so you can have a utran umts network that is alongside your eu tran and the user may move in and out and you may want to want the user to hand over across these different networks so the way you can do that is by letting your mme control all that signaling so the mme would talk to the msc that is handling your utran network and would manage all the signaling in that case the good news is with lte advance and lte advance pro nothing has changed actually on the epcps uh i just wanted to give you a good overview of the different network elements before we delve deeper uh but the all the changes that we&amp;#39;ll be talking about are happening in this box so if you still have some doubts i would recommend doing some more reading on the utran before you go any further here the network architecture is uh defined you know the same picture that we have looked at so far but i have added some functions for each of the network elements here you may want to just take a look and if you have any doubts you know just you may want to search for these before going any further so another key concept that we need to make sure we understand is the concept of bearers so you have the ue on one side and you have the other network on the other side in this case uh it is the internet and you have what is called an end to end service better this service better traverses uh your utran epc and all the way to the internet this actually is composed of your eps bearer and an external bearer the eps bearer is composed of a eu-tran radio access bearer which is the bearer or the connection between the ue and the e node b and the s5s8 bearer which is the serving gateway to the p gateway bearer and the srb drb is the better or the connection between the ue and the e node b and then you have the s1 bearer which is the e node b to the serving gateway each of these bearers depending on what kind of traffic they carry they can have a different quality of service requirement which we&amp;#39;ll look at in the next slide so yep so ltqos that we have talked about it can be a default bearer or it can be dedicated better a default bearer can uh only be a non-gbr gbr meaning a guaranteed bit rate so non-guaranteed bit rate there is no quality of service essentially and dedicated bearer can be a gbr or guaranteed bitrate error or a non-gbr and these are the attributes that each of these bearer types have a non-gbr can mostly be only qci-9 and these bearers will have certain attributes gbr is mostly qci 1 through 4 and it has these attributes so let&amp;#39;s look at what qci means qci is quality of class quality service class indicator and each of the qci has certain [Music] attributes that need to be met at the bare minimum so for example qci1 is a guaranteed bitrate bearer with the priority number two with a packet delay budget of 100 milliseconds at all allowed packet loss is 10 and an example service that may use qci one is a voip call or a volte call so so this wraps up our architecture overview uh i hope you have refreshed all the architecture concepts in lte and next we will start talking about the lte advanced features in the next section so see you in the next section you

Transcript for:LTE Network Architecture Overview

Transcript for:
LTE Network Architecture Overview