Abbreviations used in Telecommunication Industry

Here I have listed few Abbreviations that I came across during my training. 

ANC - Antenna Network Combiner

ARFCN - Absolute Radio Frequency Channel Number

BBH - Base Band Hopping

BCC - Base Station Color Code

BCCH - Broadcast Common Control Channel

BOI - Board of Investment

BSC - Base Station Controllers

BSIC - Base Station Identification Code

BSS - Base Station Substation

BTS - Base Transceiver Stations

CDR - Caller Detail Record

C/I - carrier over interfere

COW- Cell On Vehicle

CSR - Call Success Rate

DC- Dual Carrier

EIRP - Effective Isotropically Radiated Power

ETACS - Extended Total Access Communication System

FSL - Free Space Loss

GoS - Grade of Service

GPS - Global Positioning System

GSM - Global System for Mobile Communication

HLR - Home Location Registry

HO - Handover

HSN - Hopping Sequence Number

HSPA- High Speed Packet Access

IDD - International Direct Dialing

IDU - In Door Unit

IF - Intermediate Frequency

IN - Intelligent Network

IP- Internet Protocol

KPI - Key Performance Indicators

LA - Local Authority

LIU - Line Interface Unit

LTE - Long Term Evolution

MAI - Mobile Allocation Index

MAIO - Mobile Allocation Index Offset

MGW - Media Gateway

MIC - Milicom International Cellular

MIMO- Multiple-Input and Multiple-Output

MS - Mobile Station

MSC - Mobile Switching Centre

MW - Microwave

NAITA - National Apprentice & Industrial Training Authority

NCC - Network Color Code

NGN - Next Generation Network

NOC - Network Operational Centre

NPO - Network Performance Optimizer

NSS - Network Subsystem

ODU - Out Door Unit

OMCCS - Operation and Maintenance Centre Circuit Switching

OMCP - Operation and Maintenance Control Processor

OMCR - Operation and Maintenances Centre – Radio

PAT - Preliminary Acceptance Test

PDH - Plesiochronus Digital Hierarchy

PRN- Provide Roaming Number

QoS - Quality of Service

RAN - Radio Access Network

RCF - Radio Control Function

RCP - Radio Switching Point

RFH - Radio Frequency Hopping

RNE - Radio Network Engineers

RNP - Radio Network Planning

Rx - Receive

SAR - Site Acquisition Request

SDCCH - Standard Dedicated Control Channel

SDH - Synchronous Digital Hierarchy

SFH - Slow Frequency Hopping

SMSC - Short Message Service Center

SRI- Send Routing Information

SSP - Service Switching Point

SSW - Gigabit Ethernet Switch

SUM - Station Unit Module

TACS - Total Access Communication System

TC – Transcoder

TCH – Traffic/Voice Channel

TDM - Time Division Multiplexing

TIMSI- Temporary Mobile Subscriber Identity

TRC - Telecommunications Regulatory Commission

TRE - Transceiver Equipment

TSS - Technical Site Survey

TTI- Transmission Time Interval

Tx - Transmit

UMTS- Universal Mobile Telecommunications System

VAS - Value Added Services

VLR - Visitor Location Registry

VoIP- Voice over IP

WCS - Wireless Call Server

Drive Test

Drive Test will ensure the network performance and it is directly related to the QoS of the network. Normally drive tests are conducted by Technical Officers (TO) under the guidance of an Optimization Engineer. In Drive Test we drive on a vehicle which is well equipped to measure network performance. Gathered data are recorded using a drive test tool and we can analyze them later. Reasons for doing a Drive Test:

• For Network Optimization: changing antenna azimuths and tilts
• To identify network performance of area
• To troubleshoot customer complaints
• To check network coverage
• After a major change in the network E.g. After a parameter change in site 
• To check signal levels After commissioning a new site

In addition to these occasions we sometimes conduct indoor drive tests in situations when there are issues inside a building. In such situations a person wearing drive test tool and other required equipment will walk inside the building where we need to collect data. Here we face the problem of receiving GPS location. At such scenarios first a reference GPS point is taken at a location of the building. Then a sketch of the floor plan of the building is drawn on the map of the drive test tool. Then the drive test tool is taken on a path inside the building area in a fixed speed. We should travel on a fixed and steady speed because otherwise recording may not have correct details of the recorded data.

Equipment and Tools used in a Drive Test

I got to know about two Drive Test Tools. They are Ericson ® TEMS and JDSU (Agilent). TEMS is for 2G and Agilent is for 3G. Tool will record the details to a “.log” file.  Equipments used:

• A laptop computer with drive test tool installed in it
• Two mobile phones which supports the tool (one in Dedicated mode and other one in Idle mode)
• GPS module to track location
• The license dongle for the authentication of the drive test tool

Two mobile phones, GPS module and license dongle are connected to the laptop. We can upload the existing site file to the tool and according to the location of GPS, data will be recorded. When the record is done we can analyze the recorded data later.

Why MPLS

For describing purposes lets divide Internet Service Providers into three categories. They are:

• Layer 1 (e.g.: SLT)
• Layer 2 (e.g.: Etisalat, Mobitel, Dialog)
• Layer 3 (not present in Sri Lanka)

In IP routing, Router maintains two tables for routing purposes. Namely RIB (Router Information Base) and RIFB (Router Information Forwarding Base). First router looks at all the networks connected to it. Then build up the RIB including all the IPs of externally connected networks. Using RIB router builds another table called RIFB. That table includes shortest/best path of a particular source and destination. When a packet arrives to a Router, router will first check the RIFB for the destination IP. Then it will do another router lookup to find out next hop. So for each packet two router lookups needed. If this packet goes through thousands of routers in the internet it will take lot of time. Additionally at each hop source and destination MAC (Media Access Control) addresses changed. To speed up the process of packet traversing in the internet we use MPLS. 

Using Label Distribution Protocol (LDP) routers distribute their labels. LDP is not a routing protocol as OSPF (Open Shortest Path First) or IS-IS (Intermediate System to Intermediate System). As in previous case (in IP routing) in MPLS routers build two tables namely LIB (Label Information Base) and LIFB (Label Information Forwarding Base). LIB consists of labels of connected networks. And LIFB consist of label mapping of the networks. No data loss occurs as in previous case, only label switching happens. Now a large table with labels build up. To overcome, we can use a protocol like BGP (Border Gateway Protocol). Following figure will give you an idea of how a LFIB - MPLS table looks like.

 

MPLS (Multi-Protocol Label Switching)

MPLS is a mechanism in high-performance telecommunications networks that directs data from one network node to the next based on short path labels rather than long network addresses, avoiding complex lookups in a routing table. The labels identify virtual links (paths) between distant nodes rather than endpoints. MPLS can encapsulate packets of various network protocols. MPLS supports a range of access technologies, including T1/E1, ATM, Frame Relay, and DSL.

MPLS header consists of following.

• Label (20 bits)

•  QoS (3 bits)

• Bottom of Stack (1 bit)

• Time To Live (8 bits)

And a MPLS network consist of two types of routers namely Label Edge Router (LER) and Label Switch Router (LSR).

LSR: Routers that perform routing based on labels.

LER: Routers that are in the entry and exit points of the MPLS network. They push a MPLS label into the packets which are coming into the MPLS network and pop off the MPLS labels from the packets leaving the MPLS network.  Refer Figure: MPLS.