LTE :RIP

Yes, RIP - Radio Interface Protocols..LTE follows a layered protocol approach. The 5 layers can further be divided into two planes.

The following diagram will help us understand the layers, hierarchy and division of planes.

Now lets look at every single layer

1. PHY : It is also called as Layer 1 as per OSI model. This the layer where actual data is transmitted and received. This data transfer is using resource blocks. Some control mechanisms are also implemented as a function of the physical layer.

2. MAC : The second layer of the OSI model. This layer is mainly responsible for the error corrections. Terms like MIMO rank, code rate, modulation etc are related to this layer. It proves how appropriate the name "Media Access Control" is !

3. RLC : The radio link control layer. For people like me, who are working on network optimization/performance, layer 3 rings a bell! Well sometimes, it can turn out to be a nightmare.. Anyways , this layer is responsible for segmentation and concatenation of data units. Automatic repeat requests is an error correction mechanism implemented in this layer.

4. PDCP : Packet Data Convergence Protocol. : Header compression and decompression in the packet is done on this layer.

5. RRC : Radio Resource Control : pagin, maintenance, release/setup connection , QoS are the functions of this layer sitting at the top.

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LTE - Digging deeper!

Now that we have covered basics and enabling technologies for LTE.. Let's understand try to understand the standards better!

3GPP's official website is the best source to understand the standard.. It is like learning from the "GURU's" or directly getting it from the owners!

3GPP has a very well defined, organised way of working. Every project is a "Technical Specifications Group". It is divided into multiple working groups. As an example RAN TSG is subdivided into RAN planery, Radio layer 1 etc..

Again the standard is divided into multiple series.

Series 23 : SAE
Series 36 : EUTRAN
Series 24 : Signalling protocols (UE to Network)
Series 26 : CODECs
Series 37 : Multiple Radio Access.


I wish I was an expert on all this , but I am still reading and understanding them. For now, Lets focus on Series 36 : LTE (Evolved UTRA) and LTE-Advanced radio technology

Again the series is subdivided into multiple "SUB - series"! This is going to be an adventurous journey.

36.1 : It is all about Base stations conformance and radio
36.2 : Physical Layer
36.3 : Radio Access Network - Layer 2 , Layer 3
36.4 : Architecture
36.5 : UE conformance Testing
36.8 : Background and more technical reports

Now that we have a clear understanding of the nitty-gritties we are all set to start the journey!

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