In this chapter we shall see what are the different interfaces available in LTE.
First, what is an interface?
Interface is a channel that is used to communicate between two elements in an LTE network.
Why do we need an interface?
We need interfaces to deliver signaling or user data information to/from the network element.
Who defines these interfaces?
3PGG is the organization that will define these interfaces.
Below are the Interfaces available in LTE.
LTE Uu
S1-MME
X2
S11
S5
S1-U
S6a
Sp
Gx
Gy
Gz
SGi
Interface: LTE Uu
Protocol Used: E-UTRA (control plane and user plane)
Description:
It is the air interface between UE and EUTRAN (eNB).
The signaling connection is the RRC connection represented by Signaling Radio Bearer.
The user plane connection is the logical channels represented by Data Radio Bearers.
Interface: S1-MME
Protocol Used: S1-AP
Description:
It is the interface for the control plane between an E-UTRAN(eNB) and an MME.
Interface: X2
Protocol Used: X2-AP for control plane
GTP-U for user plane
Description:
X2 interface is used between 2 eNB. It is used during X2 handover and for Self Organizing Network related functions.
X2-C to transfer control plane information between 2 eNB.
X2-U to transfer user plane information between 2 eNB.
Interface: S11
Protocol Used: GTP-C
Description:
It is used as an control plane interface between an MME and an S-GW. It is used to provide GTP tunnel Per user.
Interface: S5
Protocol Used: GTP-C for control plane
GTP-U for user plane
Description:
It is an interface between S-GW and a P-GW for control and user plane.
S5 interface provides a GTP tunnel per bearer for the user plane and GTP tunnel management per user for the control plane.
Interface: S1-U
Protocol Used:GTP-U
Description:
It is an user plane interface wetween en eNB and an S-GW. It provides a GTP tunnel per bearer.
Interface: S6a
Protocol Used:Diameter
Description:
An interface for control plane between HSS and an MME.
Interface: S7
Protocol Used:Gx
Description:
It provides transfer of QoS service and charging rules from Policy and PCRF to Policy and Charging Enforcement Function (PCEF) in PDN-GW.
Interface: S10
Description:
It is a reference point between MMEs for MME relocation and MME to MME information transfer.
Interface: S11
Description:
It is a reference point between MMEs for MME relocation and MME to SGW.
Interface: Sp
Protocol Used: Diameter
Description:
An interface for control plane between SPR and a PCRF.
Interface: Gx
Protocol Used: Diameter
Description:
An interface for control plane between a PRCF and a P-GW. It is used to transfer policy control and charging rules form the PCRF to the P-GW to support QoS.
Interface: Gy
Protocol Used: Diameter
Description:
An interface between OCS and a P-GW
Interface: Gz
Protocol Used: GTP
Description:
An interface between OFCS and a P-GW
Interface: SGi
Protocol Used:IP
Description:
An interface for control and user plane between a P-GW and a PDN.
S2a, S2b, S2c Interfaces:
All these 3 interfaces are between P-GW to PDN. Based on the functionality they are divided into 3 parts. Below we shall see the functionality of each interface:
Interface: S2a
It provides user plane with related controls and mobility support between trusted non-3GPP IP access and PDN-GW.
It is based on PMIP.
Interface: S2b
It provides the user plane with the related control and mobility support between evolved Packet Data Gateway (ePDG) and PDN-GW.
It is based on proxy mobile IP.
Interface: S2c
It provides user plane with related controls and mobility support between UE and PDN-GW. It is implemented over trusted and/or untrusted non-3GPP access and/or 3GPP access.
Note:
UE to eNB is called as LTE
eNB to Core Network (EPC) is called as SAE : System Architecture Evolution
We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. By clicking “Accept”, you consent to the use of ALL the cookies.
This website uses cookies to improve your experience while you navigate through the website. Out of these, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. We also use third-party cookies that help us analyze and understand how you use this website. These cookies will be stored in your browser only with your consent. You also have the option to opt-out of these cookies. But opting out of some of these cookies may affect your browsing experience.
Necessary cookies are absolutely essential for the website to function properly. These cookies ensure basic functionalities and security features of the website, anonymously.
Cookie
Duration
Description
cookielawinfo-checkbox-analytics
11 months
This cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Analytics".
cookielawinfo-checkbox-functional
11 months
The cookie is set by GDPR cookie consent to record the user consent for the cookies in the category "Functional".
cookielawinfo-checkbox-necessary
11 months
This cookie is set by GDPR Cookie Consent plugin. The cookies is used to store the user consent for the cookies in the category "Necessary".
cookielawinfo-checkbox-others
11 months
This cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Other.
cookielawinfo-checkbox-performance
11 months
This cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Performance".
viewed_cookie_policy
11 months
The cookie is set by the GDPR Cookie Consent plugin and is used to store whether or not user has consented to the use of cookies. It does not store any personal data.
Functional cookies help to perform certain functionalities like sharing the content of the website on social media platforms, collect feedbacks, and other third-party features.
Performance cookies are used to understand and analyze the key performance indexes of the website which helps in delivering a better user experience for the visitors.
Analytical cookies are used to understand how visitors interact with the website. These cookies help provide information on metrics the number of visitors, bounce rate, traffic source, etc.
Advertisement cookies are used to provide visitors with relevant ads and marketing campaigns. These cookies track visitors across websites and collect information to provide customized ads.
