User's Manual

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Chapter 3 System Structure

LTE eNB System Description v2.0 29

The LMD1, LTE main processor of eNB plays role as the highest layer. It is

responsible for communication path configuration between UE and EPC,

Ethernet Switching functionality for internal eNB, and System OAM. Also, it

manages entire hardware and software status within eNB, allocates/manages

resources, and collect/report the alarm status information to LSM (LTE

System Manager).

 Network Interface Feature

The LMD1 is Gigabit Ethernet/Fast Ethernet, and it interfaces with EPC.

Depending on the provided interface, LMD1 can be classified as following

types, and operator can choose the interface to use.

o 100/1000 Base-T Copper (RJ-45) 1 Port

o 1000 Base-X Small Form factor Pluggable (SFP) 1 Port

o 1000 Base-X/10 GBase-SR/LR Small Form factor Pluggable+ (SFP+) 1

Port

 External Interface Feature

The LMD1 can provide Ethernet interface for User Defined Ethernet (UDE)

within CDU. Through Fast Ethernet interface of CDU, LMD1 can provide

paths to external alarm information (such as Rectifier alarm/control, battery

monitoring data or UDE/UDA). Then, this alarm information is sent to LSM.

 Clock Generation and Distribution

The LMD1's clock module generates 10 MHz, Even, and SFN (System Frame

Number) based on the sync signal which is received from GPS, and distributes

this to the Hardware block of the system. This clock maintains the internal

synchronization of eNB, and used for system operation. Clock module can

forward ‘time data’ and ‘location data’ via TOD Path.

If GPS signal was not received for some reason, clock module provides

holdover feature that can maintain the normal clock for specified time period.

LCC4-B1A

The functions of LCC4 are as follows:

 Subscriber channel processing

The LCC4 modulate the packet data, which is received from LMD1 and

transmits it through CPRI to RRH. Reversely, it demodulates the data received

from RRH and converts it to the format defined in LTE physical layer standard

and transmits it to LMD1.

 CPRI interface

The LCC4 interfaces with RRH through CPRI. As LCC4 contains a built-in

Electrical to Optic (E/O) conversion device and an Optic to Electrical (O/E)

conversion device, it can transmit and receive ‘Digital I/Q and C & M’ signals

between remote RRHs. The LCC4 can also run loopback tests to check

whether the interface between LCC4 and RRHs is in good condition for proper

communication. If necessary, the operator can run loopback tests using LSM

command.