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DT Introduction ,Analyzing Method Features ,Test Introduction ,Test Equipment and Test Classification

 

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DT Introduction
DT test is the main method in CDMA network optimization.
DT (drive test) is the method that MS moves on specific route of the coverage area and records the performance data and position
DT analyzing is using the related software to give analyzing for DT data and give the judgment for network quality in coverage, also gives solution or other scheme to improve.

DT Analyzing Method Features
1. Advantage
· According to DT the whole area signal coverage quality can be known. According to DT analyzing software, the coverage quality can be given a statistics result and this can be used to judge if the real coverage reach to the designing requirement;
· According to DT software processing, where the coverage quality is good and where the coverage quality is bad, it is very clear. This can help engineer to adjust working scheme for the entire network;
· DT test can record the real signal state and geography information for all the events (origination, handoff, drop calls). This will be very helpful to the event problem analyzing;
· In DT test, the geography features and real transmission environment can be observed; this is very helpful to give judgment for problem;
· According to DT test, optimization engineer can experience the subscriber feeling and can get the directed information to locate the problem;
2. Disadvantage
· Be absent of OMC traffic statistics data;
· Be limited in wireless side to analyze;

DT Test Equipment
For voice and data DT test, the necessary equipments are shown as Table

Note:
· DT test software is TEMS, NEMO, ZXPOS CNT1, analyzing software is ACTIX,NEMO ANALYZER ZXPOS CNA1;
· In data DT, test mobile and data card should be selected only one, and also confirm it can get to the suitable data speed. Usually prefer to select data card.
· In data DT according to operator’s requirement, FTP downloading and uploading, or iperf software are all suitable. Attention to select suitable FTP server in FTP downloading test.

DT Test Classification
1. Voice DT test: It includes coverage quality; origination quality; drop call; call quality and handoff.
2. Data DT test: It includes average data transmission speed; forward and reverse average data transmission speed.

DT Test Method Classification
1. According to loading information, it can be divided to “test with load” and “test without load”.
2. According to call holding time, it can be divided to “long call test” and “sequence call test”.

Test with load and test without load
The evaluation test can be implemented in one of the three loading method: busy hour, unloaded (light load) hour or loaded hour.
Busy hour test means the test implemented when the current network traffic is busiest. This test is suitable for the network that has already been operating for a period and can facilitate finding out existing problems in the network.

Unloaded (light load) test is implemented when there is no user or a small number of users. For a network that has not undergone large scale of number allocation, the test can be implemented in the normal period. But for a network that has already undergone large scale number allocation, the test can only be conducted at midnight when the traffic is small.

Loaded test check the network performance by simulating fixed loading condition through adding loads in forward and reverse links. In the forward link, simulate traffic load by utilizing the orthogonal channel noise simulator (OCNS); in the reverse link, apply the signal attenuator to simulate the load. For a network which has not undergone large scale number allocation, the loaded test can be implemented in normal traffic period.

While for a network with large scale number allocation undergone, the test can only be done at midnight when the traffic is small, which can accurately simulate the load and on the other hand can reduce the influence the test brings on the subscribers.

The forward OCNS loading can only reflect the network performance at the wireless side, while it can not reflect the processing capability of the system. The best reverse loading method is to use a noise simulator to add noise at the receiving end of the base station. However, as it is difficult to add a noise simulator to each base station, add reverse load through reverse load simulator. For a network that has been operating for a period, generally busy hour test is adopted.

Long call test and sequence call test
1. Voice data test
In the continuous long- time calling test, the call holding time is set to be the maximum value and automatic recall will originate when a call drop occurs. This kind of calling features a small number of calling times, and can better reflect the system handoff performance. It can be used to in the tests for some parameters such as coverage ratio, call drop rate, handoff success rate and handoff zone rate, etc.
In a sequence calling test, the call setting-up time, call holding time and call interval are set respectively to fixed values, and calls are originated periodically to test the network performance. The periodical test can better reflect the system processing capability and the test result is closer to the actual user situation. It can be used to test parameters such as call completion rate, paging response rate and call drop rate, etc.
2. Data DT test
According to the type of service, it can set with periodical call or continuous
long-time call. Generally, the former is used in testing the call completion rate of data service; while the latter is to test the items such as data throughput of single subscriber and signal sector, data service handoff, etc. and the specific call duration can vary with the tested item.

DT test route selection
According to test area, DT test can be divided to urban DT test and main roads DT test.
· Urban DT test is used to get the network performance in urban area;
· Main roads DT test is used to get the network performance in the main roads, railway, and waterway
According to test range, DT test can be divided to the entire area DT test and part area DT test.
· The entire area DT test is used to get to know the whole network performance;
· The part area DT test is used in specific area for one problem.
DT test route designing principle:
· Test path should be within the coverage range and avoid to repeating the same stretch;
· For the BTE whose coverage is connected to repeater, test route should cross their related coverage area to check the handoff performance;
· For BSC overlap area, test route should cross two BSC to check the handoff between two BSC;
· For sing carrier and multiple carriers combined network, the test route for carrier handoff should move to single carrier area from multiple carrier area and MS should use non-fundamental carrier; Each single carrier coverage test route is same as before; According to designing, the test route can be drawn or printed in map. The DT engineer and driver should be familiar to the route and the driving speed is better in even speed (30~50km/h).

 

 

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