3G Drive Test

Workspace

After installing TEMS and opening the Data collection window we need to create a workspace so, that we can save the windows for 3G drive test, saving us from tedious work of opening it every time we want to collect drive data.

We need to open a new worksheet for the same and the procedure has been shown in the following slide.

Workspace

Worksheet

Once we have opened a new worksheet, we will start with a map which shows us our current location and also guides us the area and the roads we need to cover with the help of GPS.

It also displays all our Node B’s.

Map Window

Select presentation on the information bar. Go to positioning and select map.

Cellfile Load

To see the NodeBs installed in the operator’s network we need to add the cellfile to our Map.

Following are the steps for same – Go to configuration on the tools bar. Select General. Select Cellfile Load. Go to ADD and select the required cellfile.Following slide shows the same-

Loading Cellfile

Select General

Cellfile Load

Vectors

Open Map

Layer Control

Vectors

In the above snapshot select the second icon from left which shows “open map” and browse for vectors.

Select the vectors and put them on the map to show the roads highways, railways etc.

We can also remove and add things by going to “Layer control” option on top of the map toolbar.

Workspace

Now we will see various windows we need to open for 3G drive test.

3G stands for 3rd Generation. In technical terms it is also known as WCDMA WCDMA – Wide Band Code Division Multiple

Access. It is called WCDMA because it uses code division

multiple access on a large bandwidth of 5MHz. This 5MHz frequency is further divided into 512

Scrambling codes. Before going into further details lets see the

windows we need to open for drive test -

Serving/Active Set + Neighbors

Layer 3 Messages

Radio Parameters

WCDMA HSPA/GSM Data Line Chart

GSM Neighbors

We can see a lot of aspects of 3G with the use of the windows we have opened for data colletion.

Serving/Active Set + Neighbors This window contains a lot of aspects of

3G and has a lot to be explained – Cell I.D – This is the identity or name

given to a particular Node B and its cell by the operator.

UARFCN – It is the frequency band allotted to the operator. One spectrum bandwidth is of 5MHz in WCDMA or 3G.This window shows us the centre frequency of the bandwidth allotted to the operator.

Serving/Active Set + Neighbors Cell Name – It is the name given to

particular Node B’s by the operator generally along the lines of the name of the area the Node B is located in.

Scrambling Code – Scrambling code is a code assigned to a particular cell. There are 512 such codes for the network to differentiate among different Node B’s and these codes can be repetitive. They are of two types primary and secondary.

Serving/Active Set + Neighbors AS – This stands for Active Set. Active Set is

the set of Scrambling Code which the U.E is currently latched on and there can be a maximum of 6 Scrambling codes in Active Set.

MN – MN Stands for monitored neighbor i.e the neighbor cell that is detected by the U.E as a neighbor and is also defined as a neighbor in the network. U.E will initiate a Handover onto the monitored neighbor in case the monitored neighbor has a stronger Rx level than the AS.

Serving/Active Set + Neighbors DN - DN stands for Detected Neighbor and

as the name suggests it is the neighbor detected by the UE but, is not defined in our network . Hence, the U.E does not handover to the detected neighbor. It can be because of Overshooting of a site, incomplete neighbor list or in case of a new site. It is very important to optimize and have no DN’s as they are one of the major reasons of Call drops in 3G.

Radio Parameters

CPICH Ec/No – Common Pilot channel Ec/No is the ratio of energy of the chip and the combined power of all the signals including the pilot itself received by the UE at that particular point. It is a very important factor for call quality.

CPICH RSCP – Received Signal Code Power is the level of the signal received by the U.E from a particular pilot.

Radio Parameters

Radio parameters are the parameters of a Mobile equipment –Tx Power – As the name suggests it is the

transmitting power of a Mobile Station. Its value can vary from

-50 to 50. The minimum the Tx power of the Mobile station the better it is for call quality.

UTRA Carrier RSSI - It is the Received Signal Strength Indicator of the Mobile Station or the U.E. It tells us the total Power Received by the Mobile Station from all the Pilots including itself at that particular location.

Radio Parameters

SIR – It is the signal to interference Ratio is the ratio of Energy in the DPCC(Dedicated Physical Control Channel) to that of the interference and noise received by the U.E.

Target SIR – It is the target Signal to Interference ratio that Mobile Equipment is supposed to achieve by increasing or decreasing its power. It is set by the use of Power Control procedure.

Radio Parameters

SQI - It is the speech Quality Index which is a parameter to rate the voice Quality on that particular call. It ranges from 0 – 30 with 30 being the best quality.

RRC State – It tells the current state and channel as in Idle or dedicated.

Mode – It is the mode that we are using GSM or WCDMA.

Layer 3 Messages

Layer 3 Messages are the messages on the Uu interface i.e between Mobile station and the Node B.

GSM Neighbors

This window is very helpful in case of 2G – 3G Handovers as we can see all the 2G neighbors of that particular 3G cell in the compressed mode state which would be explained later on.

HSPA/GSM Line Chart

This window gives us the data speed for both 3G and 2G modes depending on which mode the mobile equipment is.

RLC DL Throughput – This is the total throughput on the downlink at that particular point.

The speed shown in this window as throughput is in Kilobits/sec.

Active Window

Handovers

In UMTS there are the following type of Handovers-Intra Frequency Handovers- Softer Handover – The HO’s that take place

between any sectors of the same node B come under this category.

Soft Handover – The HO’s that take place between different Node Bs running on same frequency are called soft HOs.

Inter Frequency Handover- Hard Handover – The HO’s that take place

between Node Bs running on different frequencies. HOs from 2G-3G fall under this category.

Active Set Update

In 3G there can be six pilots in the active set. But, we generally set it at maximum of three(depends on the operator) to avoid Pilot pollution. In case of soft Handover all the cells which are in MN can be entered into Active set but, only till the maximum limit of three. This procedure of soft HO from monitored to Active set is called Active set update.

Active Set Update(Soft HO)

Monitored Neighbor

Current Location

Active Set Update(Soft HO)

Current Location

Added to Active Set

Active Set Update