Eps bearer
- LTE EPS is a connection-oriented transmission network and, as such, it requires the establishment of a “virtual” connection between two endpoints (e.g. a UE and a PDN-GW)
- This virtual connection is called an “EPS Bearer”
- It provides a “bearer service”, i.e. a transport service with specific QoS attributes.
- The LTE QoS parameters associated to the bearer are: QCI, ARP, GBR and AMBR.
EPS LTE
A data radio bearer transports the packets of an EPS bearer between a UE and an eNB in LTE.
When a data radio bearer exists in lte, there is a one-to-one mapping between this data radio bearer and the EPS bearer/E-RAB in lte.
An S1 bearer transports the packets of an E-RAB between an eNodeB and a Serving GW.
An S5/S8 bearer transports the packets of an EPS bearer between a Serving GW and a PDN GW.
The QoS parameters associated to the bearer are: QCI, ARP, GBR and AMBR.
Eps bearer in lte
- A low priority signaling (message) bearer (SRB1)
- A high priority signaling (message) bearer (SRB2)
- A data radio bearer (DRB), i.e. a bearer for IP packets
Eps in lte
Part of the bearer establishment procedure are authentication and activation of encryption.
The required data for this process is retrieved by the base station (the eNodeB or eNB in 3GPP talk) from the Access Gateway (aGW), or more precisely from the Mobility Management Entity (MME).
The MME also delivers all necessary information that is required to configure the data radio bearer, like for example min/max bandwidth, quality of service, etc.
What is EPS Bearer in LTE?
In LTE, an EPS (Evolved Packet System) Bearer is a virtual connection that transports user data between the user equipment (UE) and the core network. It is established to carry different types of data (like voice, video, or web browsing) and applies Quality of Service (QoS) rules to ensure that the right performance is maintained for each service.
Key Functions of EPS Bearer
- Data Transport: The EPS Bearer is responsible for transporting user data from the UE through the LTE network to the Packet Gateway (PGW) and vice versa. Each bearer is associated with a specific QoS level for optimal data delivery.
- Quality of Service (QoS): Each EPS Bearer is assigned a QoS profile that defines parameters like priority, packet delay, and packet loss rate. These parameters ensure the data is delivered as required for each application (e.g., low latency for voice calls, high bandwidth for video streaming).
- Bearer Management: The bearer is created, modified, or deleted based on the needs of the application. For instance, a new bearer can be created when a user initiates a VoIP call to ensure the voice data has a high priority.
Types of EPS Bearers
- Default Bearer: Every device is assigned a default bearer, which provides basic IP connectivity. It carries general traffic without any special QoS requirements.
- Dedicated Bearers: These are created for specific services that require a higher level of QoS. For example, a dedicated bearer is set up for high-priority services like voice calls or video streaming.
How EPS Bearers Work
When the UE connects to the LTE network, it is assigned a default EPS bearer. If the user starts a service requiring specific QoS (like video streaming), a dedicated EPS bearer is set up with the appropriate QoS profile. This ensures that each type of service gets the right amount of bandwidth and priority to function optimally.
Why EPS Bearers Matter
EPS bearers are crucial in LTE because they allow the network to provide different services with the required performance. Whether it’s a voice call, video chat, or browsing, the network uses bearers to ensure that each service meets the required QoS for a smooth user experience.