LTE optimization (LTE and LTE A overview)
LTE stands for Long Term Evolution and starts from Relaeas 8 in 3GPP Standard .
LTE requirements are specified in 3GPP TS25.913. Main requirements are:
- Peak data rate of 50 / 100 Mbps (uplink / downlink)
- Reduced latency enabling RTT (round trip time) <10 ms
- Packet-optimized
- Improved spectrum efficiency between 2- 4 times higher than Release 6 HSPA
- Frequency flexibility: standard defines 15 FDD and 8 TDD operating bands
- Bandwidth scalability with allocations of 1.4, 3, 5, 10, 15 and 20 MHz
- Operation in FDD and TDD modes
- Support for inter-working with WCDMA and non-3GPP systems (i.e. WiMAX)
- Good level of mobility: optimized for low mobile speeds (up to 15km/h) but support also high mobile speeds (up to 350km/h)
- Improved terminal power efficiency
- it is by offering high-data-rates with low-latency, improving services, lowering the costs and allowing for spectrum refarming thanks to the frequency and bandwidth flexibility
Architecture :
The LTE / EPC architecture is driven to optimize the system for packet
data transfer. There are no circuit switched components.
EnodeB Functions :
- Radio Bearer Control: setup, reconfiguration and release
- Admission Control
- Scheduler
- Transmission of Paging messages and of Broadcast information (SIBs)
- Measurement collection and evaluation
- User data routing to the S-GW/P-GW
- MME selection at attach of the UE
- Security: Ciphering and Integrity protection on the radio interface
- IP header (de)compression
- Connection Management Control : UE state management
Mobility Management Entity (MME) :
- Subscriber attach/detach
- Tracking area updates
- Triggering and distribution of paging messages to UE.
- Security and roaming control
- Authentication, integrity protection
Serving Gateway (S-GW):
- Manages the user data in the EPC. Receives packet data from the eNodeB and sends packet data to it.
Packet Gateway (P-GW or PDN-GW):
Connection between EPC and external Packet data Networks
(PDN). Comparable in functionality with the GGSN in 2G/3G networks.
- IP address allocation for UEs
- Packet routing / forwarding between S-GW and external data networks
- Firewall functionality
Policy and Charging Rule Function (PCRF):
- As the name indicates, it is responsible for implementing the charging policy and also for the QoS negotiation with external packet data networks.
Home Subscriber Server (HSS):
- Permanent and central subscriber database containing
mobility and service data for each subscriber. It also contains the AuC (authentication
centre) functionality
TAGS : GSM , UMTS , LTE , Telecom Engineer , Optimization