zk celltest, inc. indoor rf measurement and analysis

ZK Celltest, Inc.

Indoor RF Measurement and Analysis

ZK Celltest, Inc 256 Gibraltar Drive

Suite 109 Sunnyvale, CA 94089

www.zk.com 1-800-TESTCEL

ZK Celltest, Inc. Indoor RF Measurement and Analysis

Confidential & Proprietary

Introduction The ZK products can be used to collect RF network parameters in order to facilitate network design, optimization, and performance. This paper describes how the ZK units and software can be used to design and optimize indoor facilities such as sports stadiums, convention centers, resorts, etc. To do indoor measurements the ZK-SAMp, ZK-MPSp or the ZK-MPS/B can be used to collect the data. For post-processing the user can import data into programs like Actix, Windcatcher and IB Wave or they can use ZK’s KPI Mapper. A brief description of each of these products is provided.

ZK-SAMp

Figure 1: ZK-SAMp

The ZK-SAMp weighs less than 3 lbs and comes with in a side/backpack. It can be shifted to the side for cable and device setup and can be swung around to the back for walk testing. Five devices can be connected to the units to test multiple carriers and technologies including 2G, 3G and 4G.

ZK-MPSp

Figure 2: ZK-MPSp

The ZK-MPSp is similar to the ZK-SAMp except that it has an internal scanner that can scan either 700/850/1900 bands or 850/1900/2100AWS bands. The scanner uses one of the USB device ports so there are four ports available to connect handsets/devices.


Confidential & Proprietary Page 2

ZK-MPS/B

Figure 3: ZK-MPS/B

The ZK-MPS/B is similar to the ZK-MPSp except it will scan all four bands 700/850/1900/2100AWS simultaneously and it has 11 USB ports to connect external handsets/devices. This product is ideal for performing benchmark testing indoors or outdoors.

KPI Mapper

Figure 4: KPI Mapper Indoor Plot

KPI Mapper allows you to import the indoor data into a MapInfo workspace such as the one shown above. Detailed analysis can be performed using MapInfo.



Figure 5: KPI Mapper Export to Google Earth Plot

KPI Mapper also allows the user to import the data into Google Earth so that 3D images can be shown.

Test Location The test that was performed was conducted at Stanford Stadium in Palo Alto, CA. The product used was the ZK-MPSp and the data was analyzed with KPI Mapper.

Figure 6: Stanford Stadium



Test Equipment The ZK-MPSp was setup with an LTE handset on channel 5230 connected to port 2 and a LTE handset on channel 5780 connected to port 3. The scanner was configured to scan bands 850, 1900 and 2100 for CDMA, EVDO, UMTS and LTE. The goal of the test was to obtain general coverage and throughput information for the indoor DAS. A typical Cellular/WiFi antenna setup is shown below.

Figure 7: DAS Antenna System



Field Test A simple walk around the stadium was performed. A bitmap image of the seating chart was imported into the ZK-MPSp and the user walked around the stadium dropping breadcrumb points on the image. The seating chart image below was downloaded from the Internet and used. An Android app called Coverage Maps was used on the handset to download and upload test files. This app alternates between an upload, a download and a signal strength test so an upload (and download) is occurring one third of the time.

Figure 8: Imported JPG image used by the ZK-MPSp



Output Analysis It took a few minutes to unpack and setup the equipment and about 30 minutes to walk around the stadium and collect data. The data was logged to the internal Compact Flash memory card and the files were transferred to a computer for analysis. Quick check of the data was performed on site with KPI Mapper to verify collection. Analysis was performed in the office.

Throughput and Coverage Downlink throughput and RSRP plots are shown below for the two carriers (chan 5230 and 5780). Data is displayed in Bytes/Sec. To convert to Mbps multiply by 8 to convert to bits/sec and divide by 1,000,000 to convert to Mbps. Note that even the highest throughput of 49,000 Bytes/sec equals only 0.392 Mbps, hardly acceptable LTE speeds. This is because the testing was done in an empty stadium and the carriers increase the capacity only during games. Also, disregard speeds below 15,000 Bytes/sec. Downloads are occurring one third of the time due to the sequential testing of the Coverage Map app and these slow download speeds are occurring during the upload portion of the test.

Figure 9: RLC throughput for Channel 5230



Figure 10: RLC throughput for Channel 5780

We can see that channel 5230 functions at roughly twice the data rate as channel 5780. The following maps show the signal levels or RSRP.

Figure 11: Channel 5230 RSRP



Figure 12: Channel 5780 RSRP

It is fairly obvious that the RSRP coverage of channel 5230 is much better than 5780 which most likely is the cause for the improved throughput speeds.



Scanner Data The plots below are from the scanner. They show the level of the Scrambling code and strongest PN for the 850 MHz Band A and 850 MHz Band B respectively. Both Carriers are transmitting a strong signal in the 850 band. There doesn’t seem to be any coverage issues for 3G service in the 850 band.

Figure 13: Strongest SC Ec/Io for 850MHz Band A



Figure 14: Strongest PN Ec/Io for 850MHz Band B

Conclusion A fairly simple and analysis test was performed in order to measure throughput and coverage of the two top carriers in the area. On a day when a game was not being played both carriers had relatively low LTE throughput levels. This could be due to the carriers using this capacity elsewhere while a game is not being played. However, channel 5230 had roughly double the throughput than 5780. Looking at the RSRP plots this is most likely due to a 700 MHz coverage issue. A quick check of the 850 band using the scanner data revealed strong coverage for both carriers. Further analysis could be done depending on the use of the data. For example, the scanner data could be used to determine the strongest scrambling codes and PN to determine a good donor signal for the DAS. Or, the external network could be measured in order to determine the level of interference on the indoor network. Additional devices could have been added to test 3G data throughput and coverage or to test the performance of the other wireless carriers.



The log data can be imported into RF Planning software to facilitate DAS design or outdoor network design. By connecting multiple devices and scanning, all the data needed for multiple uses was collected in less than an hour. Once the data is collected it can be brought back to the office and used for design, optimization, benchmarking, marketing, etc. The ZK products are designed to make field testing simple and productive. The log data has an open interface allowing it to be transferred to third party software.

zk celltest, inc. indoor rf measurement and analysis

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