The exploding growth of the internet and associated services in the past few years has fueled the need for more and more bandwidth. Handheld devices are growing exponentially and thus the need for the services on the move has increased tremendously. Current 3G technology is able to cope with the demand to some extent but unable to satisfy the needs completely.
Long Term Evolution (LTE) promises higher data rates, 100Mbps in the downlink and 50Mbps in the uplink in LTE’s first phase, and will reduces the data plane latency and supports interoperability with other technologies such as GSM, GPRS and UMTS. Plus, LTE has support for scalable bandwidth, from 1.25MHz to 20MHz. All these features make LTE a very attractive technology for operators as well as the subscribers.
In this paper we briefly touch upon the procedures executed by LTE user equipment (UE) and the various LTE network elements in order to provide the services requested by the UE.
Network Architecture
In Figure 1, the architecture of the LTE network is given with the various interfaces between the network elements; GERAN and UTRAN networks are shown for completeness.
Figure 1: LTE Network Architecture
- eNodeB: Radio Resource Management functions, IP header compression, encryption of user data streams, selection of an MME, routing of user plane data to S-GW, scheduling and transmission of paging message.
- MME: NAS signaling (eMM, eSM) and security, AS security, tracking area list management, PDN GW and S-GW selection, handovers (intra- and inter-LTE), authentication, bearer management.
- S-GW: The local mobility anchor point for inter-eNodeB handover; downlink packet buffering and initiation of network-triggered service requests, lawful interception, accounting on user and QCI granularity, UL/DL charging per UE.
- P-GW: UE IP address allocation, packet filtering and PDN connectivity, UL and DL service-level charging, gating and rate enforcement.
There is much more!
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Response from Rambabu: Thanks Rajendra for your interest on the LTE Signaling Procedure white paper. This paper talks about the key Signaling procedures exchanged between various nodes in LTE technology for frequently-used scenarios. The HSPA to LTE network or, 2g to LTE convergence, is a little more complex and a bigger topic — so I may not able to explain in detail as a response to this thread but will be good for us to address in a separate white paper.
For now, I will give a high level overview and a few important references in this area, which hopefully will help provide a better understanding.
The interfaces S12 (UTRAN to SGW), S4 (SGSN to SGW), S3 (SGSN to MME) will play a key role during HSPA to LTE.
Refer to the following 3GPP specifications for more details:
23.060 ( Release 8 )
23.401 ( Release 8 )
http://www.cisco.com/en/US/solutions/collateral/ns341/ns973/ns1076/white_paper_c11-609205_ns1078_Networking_Solutions_White_Paper.html
Thank with regards,
Rambabu Gajula
Response from Rambabu: Thanks Jayateerth for showing your interest on LTE Signaling Procedures. This white paper has been written by keeping 3GPP Release 8 specifications from a few years back. The new services you have mentioned, MCE (eMBMS), are added in Release 9. These new features will be covered in a separate future white paper if time permits. FYI, the interfaces added for these features are M3 (MME to MCE), M2 (MCE to eNB) and M1 (eNB to MBMS CP/UP). Thanks, Rambabu
Response from Rambabu: Thanks Prasad for your interest on LTE Signaling Procedures. This paper describe the LTE Layer 3 and Layer 4 control plane procedures in LTE nodes to establish the connection for data plane where the user’s application starts running. These procedures may not change drastically depending the data (Femto applications) / voice applications. If you are interested about any specific application then please let me know. I will try to provide more details. Thanks with regards, Rambabu
for exploring the LTE_Femto presence based applications and content synch applications, I would like to know the call flow so that the scope of the applications and the middleware requirements can be ascertained.
Hi,i would like to know we are using the HSPA how we can converge from HSPA to LTE network & how we will route the call from 2G to LTE.
i need something more about MCE Server (Multicell/Multicast Coordination entity)…
Wanted to have end to end call flow for LTE. Can you please provide me some document which has that.
The query is about how to migrate from a UMTS (3G) network to a LTE (4G) network. In LTE up to release 9, there is no circuit switched voice support, hence the migration is difficult to achieve without service disruption (indeed, I can say impossible as of now). However, 3GPP is taking up this issue in Release 10.
This is good document. It will be better if we can get some information about how to evolve from Release 4 to LTE.
What are the requirements for current CS and PS core networks?