Once you’ve completed that LTE section, you’ll be able to learn the EPS UE bearers as well as connectivity. EPS bearer terminology of its endpoints and the QoS capabilities. You can also lean the radio bearer S1 bearer as well as S5/S8 bearer which are linked with the EPS bearer, and so on.
- determine EPS bearer terms and conditions of its endpoints , as well as QoS features
- provide the reason the reasons why that the S1 radio bearer as well as the S5/S8 bearer have a connection to the bearer of EPS.
- clarifies the significance of the QCI value in defining the QoS applicable to the bearers of EPS
- define the various kinds of traffic are handled by various bearers to similar UEs.
- defines the way in which data packets are structured and sent through appropriate bearers of EPS that are connected to a single U.E.
- explain the significance and operation of default bearers
- describe the procedure to establish an EEPS bearer
- determine and identify the main identities of EPS networks”hierarchical regions.
- determine the identities used with respect to users and the UEs.
- describes the method that is used for the UE to register as a user of the EPS, along with the IMS
- provides the most significant strategies for managing mobility
- define the operating principles of CS fallback.
- Define how the the home ENB (femtocell) is connected in LTE EPS. LTE EPS
LTE EPS Table Of Content
- The EPS as an IP-CAN.
- EPS Quality of Service.
- EPS Bearer QoS Class Identifiers.
- ARP (Allocation and Retention Priority)
- QoS Levels.
- EPS Bearer Types.
- EPS Bearer Composition.
- EPS Bearer Establishment.
- EPS Area Identities.
- Subscriber Identities.
- LTE State Management.
- EPS Service Concepts.
- Device Selection.
- EPS Initial Attach.
- Default Bearer Establishment.
- IMS Registration.
- CS Fallback Attach.
- EPC Support for Idle Mode.
- TAU (Tracking Area Update).
1. The EPS as an IP-CAN
The EPS does not provide any services for the user, aside from connection to an external packet data network. In this regard the EPS is able to work as an IP-CAN. The particular services the users receive are offered by platforms for service that are used in outside PDN.
2. EPS Quality of Service.
QoS in the EPS can be defined as a mixture of the following four variables:
QCI (QoS Class Identifier)
ARP (Allocation and Retention Priority)
GBR (Guaranteed Bit Rate)
MBR (Maximum Bit Rate)
3. EPS Bearer QoS Class Identifiers.
To ensure that the same levels of QoS are offered across different operators networks to ensure that the same level of QoS is available, the 3GPP has established a specific number of QoS levels which are standardised for all operators. Every QoS degree is presented by the QCI value. The QoS goals that are associated with the respective QCI value are displayed within the tables. It is apparent it is evident that there exists a large divide of GBR in addition to non-GBR options. There are goals for the delay budget as well as loss of packets. In addition, each QCI is assigned an amount of priority. This helps in prioritizing resource allocations in the eNB.
4. ARP (Allocation and Retention Priority).
This EPS ARP facility lets the system handle busy and overloaded time. Every QoS class associated with an ARP level. It determines the significance of the EPS bearers, based on the classes. There are 15 levels of ARP, which range from Priority 1 (highest) all the way to Priority 15 (lowest).
The other components of ARP are just “yes” or “no” parameters. They include the connection’s Preemption capacity, that determines its possibility of of preventing other connections that are not as important and Pre-emption Vulnerability, which determines if it can be secured from more important connections.
5. QoS Levels.
The QoS Levels of the EPC is currently determined with the help of three levels: GBR MBR as well as AMBR (Aggregate Maximum Bit Rate).
GBR connections offer an unrestricted rate of data which allows them to carry certain kinds of delay-sensitive live-time data. MBR connections are not 100% guaranteed, but they are variable-bit rate service with a set maximum speed. If a connection’s speed exceeds the limit set and the network decides to remove the traffic that isn’t being used.
6. EPS Bearer Types.
Each bearer can offer only one definition of QoS and users are able to make use of multiple services. The UE could be using multiple bearers currently in use and offering different levels of QoS to different applications. For instance one person may use a browser, but is also making phone calls. This could need two different levels of QoS. There is and the requirement for two bearers of EPS, and one bearer per various traffic flow. In addition the need for signaling for the provision of services which could mean the inclusion of a third bearer.
7. EPS Bearer Composition.
The EPS defines a union of can be used by a radio bearer using the air interface, as also an S1 bearer and an S5/S8 bearer. Each bearer is described in a different way and the connection between these bearers is accessible at each Node. Particularly, the link with the radio bearer which is located on the S1 interface, as well as an air bearer on the S1 interface, which is available in the eNB is known as the E-RAB (E-UTRAN Radio Access Bearer).
8. EPS Bearer Establishment.
The process of creating an EPS bearer with a brand newstablishment occurs via the PCRF. This could be due to an application from an application function called AF (Application Function) inside another PDN for the establishment of that UE initiated or ended service, or the establishment of the default bearer EPS when it is established that the UE is registered to this system.
The PCRF is the only one who has for managing PCC (Policy Control as well as Charging) and, as such, is the one who decides the moment when an EPS bearer is required and what the QCI amount is needed to determine the worth that the bearer will receive. This information is sent to the PDN-GW via and Charging) using the PCC determination Provision messages.
9. EPS Area Identities.
The EPS still utilizes the PLMN identification code used by old 3GPP systems. It is made up by two numbers: MCC (Mobile Country Code) and the MNC (Mobile Network Code). MNC (Mobile Network Code).
This is also known as the MMEGI (MME Group Identifier) is a 16-bit identification number that is used to a particular MME Pool. The MMEGI is not required an exclusive PLMN.
The abbreviation”TAI” (Tracking Area Identifier) is similar to the LA (Location Area) or RA (Routing Area) identifiers employed by the GERAN/UTRAN since they can be used to identify cells that form connected to an access network. For E-UTRAN the TAI (Tracking Area) is the extent to which the location of the UE is tracked. It also is the region where the UE is requested to be called upon to be paged. The TAI includes the networks’ MCC as well as MNC, which are followed by TAC (Tracking Area Code).
10. Subscriber Identities.
The most common method of the identification of the EPS subscriber can be found in IMSI (International Mobile Subscriber Identity) that is permanent associated with a subscriber’s account. In addition there are two other identifiers: IMEISV (International Mobile Equipment Identity and Software Version) and MSISDN (Mobile Station ISDN Number) can also be utilized to serve as LTE identifyrs.
11. LTE State Management.
The LTE State Management to ensure that it provides an efficient service to UEs to ensure that it can provide efficient service. EPS must be able in setting up and keeping in mind the accessibility and availability of each terminal. It does this by keeping two contexts for each UE which are: The EMM (EPS Mobility Management) context as well as the ECM (EPS Connection Management) context
12. EPS Service Concepts.
When it comes to attaching in the Attach process the EPS will establish at a minimum, a default bearer for the UE. The specifics of the default APN which will be used as the bearer will be available inside the HSS profile of the subscriber, or it could be selected automatically through an EPC.
HSS information could determine if dedicated bearers have to be made in addition in addition to the standard bearer that was in place at the moment of attachment.
Every UE, regardless of the number of bearers for EPS it’s made, and its PDN Connectivity Services it is employing, is handled by 1 MME or S-GW at any time (except for the brief but inevitable overlap after a move occurs).
13. Device Selection.
Each bearer of the EPS system is moved through a specific number of devices. In the instance of an EPS bearer, which is set up between the E-UTRAN home of the UE and home EPC the list of devices could include one eNB MME and an S-GW and an PDN-GW. Because each network is expected to include various kinds of devices that are connected with it, the way of devices required to support a bearer must to be clearly defined. The process of selecting devices to be used for EPS connections is done in the following way. The UE chooses which eNB that it will make use of based on its air interface selected and then reselects.
14 EPS Initial Attach.
The aim that is set by the UE when connecting the device is to confirm the subscriber’s identity and address to the network to allow to allow access to services. When attaching the device, this UE gets an default bearer EPS, which provides uninterrupted connection to an PDN. The UE might be given information about an local PCSCF which will permit it to join an IMS.
A brief outline of the process for attaching when it’s an initial attachment containing information retrieved from a previous context for an UE which uses its H-PLMN (Home Public Land Mobile Network) and is accessed via the Home E-UTRAN. The process is illustrated and the steps that must be followed are outlined in the following.
15. Default Bearer Establishment.
A default bearer must be set up and the MME selects the SGW that is able to manage it, as being an PDN- GW which can be configured to support the APN. The MME issues an Request for CreateDefault bearer to the chosen S-GW that assigns a GTP TEID to which is assigned to the bearer in that EPS then forwards it to the specified PDN-GW. If the network uses dynamic PCC The PDN GW will look through the PCRF assigned to the UE to find specific parameters for the bearer. If otherwise, the bearer will be made using local QoS settings which are stored in the PDN-GW.
16. IMS Registration.
If an EPS bearer is installed and a default EPS bearer installed, the UE can sign up services through the IMS in the event that the PLMN is using an IMS and is accessible via it’s default APN. However, before the UE can be registered with the IMS it must first complete the P-CSCF’s discovery. This can be accomplished during the process of attachment in the case there is an address assigned to the local PCSCF is provided by the PDN-GW once the default bearer has been made. It is also likely that UE might need to start an independent discovery query for P-CSCF. When the local PCSCF is found then the UE might send a SIP registration message.
In the absence of roaming In non-roaming situations, the P-CSCF can be contacted by HSS directly. HSS directly identifies subscribers’ S-CSCF. In the event that roaming becomes necessary, the P-CSCF being visited must forward the request to an I-CSCF and also an S-CSCF in that subscriber’s home network who will take the appropriate action.
17. CS Fallback Attach.
In the event that there’s an UE with a connection to the internet and the networks supports CS Fallback, the UE will request CS Fallback registration during the attachment procedure. The service is available in areas with the overlap of E-UTRAN and GERAN/UTRAN the coverage of GERAN/UTRAN.
An Attach Request request which is set with the attach Type set to EPS/IMSI attachment and also an CS Fallback activated flag will be sent through MME. MME. This activates the combined attach process inside the MME. The MME calculates its number from the VLR VLR responsible for the location area that is connected to the actual tracker area. It is part of the data built to the MME and is not continuously available. The MME utilizes the Gs interface. It’s an upgraded version of the Gs interface, which gives the possibility of connecting with older SGSNs and MSCs.
18. EPC Support for Idle Mode.
The MME which is currently serving each UE is responsible for ensuring the accessibility of its services. It does this by checking the terminal’s TA that is where the terminal is.
The EPS allows cells to be member of multiple TTA. This permits the UE to move between connected TAs, without the need to execute the TAU (Tracking Area Update), which could reduce the amount of communication related to the location required but it can increase the quantity of panning needed for all UE connectivity.
The MME displays this enhanced mobility by maintaining an TA list for each registered UE that includes it lists the TAs what the UE is registered at the moment.
19. TAU (Tracking Area Update).
A TAU is activated by the UE and the MME to which it’s registered. It is initiated through an UE sending a notification to the MME of any changes to the TAI after the reselection of cells. TAUs are also used for the initial attachment procedure. It is also activated through events like the expiration of the normal TAU timer, or even as an integral part the MME load balancers, or Rebalancing.
In the message flow shown in this instance, it’s assumed there’s a connection to HPLMN when HPLMN and the UE and HPLMN, and that an MME modification or SGW relocation are not required. When it is determined that there’s a change in TAI , the UE sends a request for TAU an email to ENB. The TAU Request contains the previous TAI, the old GUTI as well as information about the condition of bearer’s EPS.
The primary function of the TAU procedure is to ensure that MME has a clear understanding of where each UE whenever there is traffic that is coming to be able to provide. Paging is usually activated upon receipt from the S-GW downlink notification the MME which signifies that data has entered the S-GW that is part of an EPS parked Bearer.
If it is necessary to call to the user who is idle (that has not been connected UE who is in into the ECM-IDLE status) it is the MME employs the paging process. Without a similar router with RNC the EPS paging procedure is managed by the MME together using ENBs. If a panning message is required to be transmitted, the MME to review its current list of available TAs that are available for the desired UE and incorporates the information about paging into the messages for paging S1 that are delivered to all eNBs having the TAs listed.