Though RLC (Radio Link Control) layer in LTE is similar to that of UMTS, but still there are some significant differences. One of the big change is RLC LTE header structure for different PDU (Protocol Data Unit) types. When it comes to LTE, RLC can have the following PDU types RLC TMD PDU RLC UMD PDU RLC AMD PDU RLC (more ..)
Power Headroom Report MAC control element tells if UE can transmit at a higher transmission power or not. In basic terms this indicates how much relative transmission power left in the UE. So a simple formula for Power Headroom in LTE is Power Headroom = UE Max Transmission Power – PUSCH Power = Pmax – P_pusch So if Power Headroom (more ..)
While studying the MAC specification today, I thought it would be a good idea to check the MAC Buffer Status Report (BSR) control element details. I had following questions in my mind about Buffer Status Report: Why is this control element used in LTE? What are different BSR CE formats?
This tutorial explains how LTE downlink maximum throughput is determined. This is a simple and straightforward formula for data rate calculation. The maximum data rate depends on channel bandwidth. As LTE uses different channel bandwidths both for FDD and TDD. Let’s take the example for LTE using FDD, where channel bandwidth can be 5 MHz, 10 MHz and 20 MHz. (more ..)
A few weeks ago I was looking into an issue related to E911 or Emergency call over the IMS network. Though it appears as most of the concepts related to emergency calls are still same in IMS as compared to legacy systems, such as 3G and GSM, there are many new things are added for IMS. Both in UMTS and (more ..)
This tutorial describes the specific details of the LTE MAC layer or the Medium Access Control protocol. MAC is a radio network protocol which resides both in the UE and in the E-UTRAN. Also, it should be noted that MAC protocol is available for both User plane and also for the control plane. RRC (Radio Resource Control) protocol is in (more ..)
When LTE system was developed one of the big technical feature from UMTS Soft/Softer handover was missing from the architecture. There are many specific reasons why LTE dropped altogether soft handover (connect-before-break) from the system design. Before discussing about why LTE skipped soft handover and only implemented hard handover, let’s check the basic concept of soft/softer handover.