LTE Advanced Test Guide CellAdvisor JD745B or JD785A/B Series (FW 3.085)

Transcription

1 LTE Advanced Test Guide CellAdvisor JD745B or JD785A/B Series (FW 3.085) Table of Contents 1. Scope CellAdvisor Overview LTE Carrier Aggregation Test Objectives Interpreting results Test Setup LTE Advanced Modulation Analysis LTE-Advanced Spectrum Analysis LTE Advanced Over-The-Air Modulation Analysis Technical Support Page 1 of 15

2 1. Scope This document describes how to test LTE-Advanced, including carrier aggregation and MIMO 4x with CellAdvisor JD745B or JD785A/B (CellAdvisor). Ideal measurement conditions for accuracy is performing a conducted test in the radio s antenna ports with RF couplers and combiners. However, to perform inservice testing and verification this test procedure considers over the air (OTA) testing. OTA measurements conditions are ideal with a direct line of site of the antenna within the corresponding sector beamwidth, which it is typically 120º. Caution: Avoid overloading the instrument setting the proper attenuation and avoid personal exposure to areas of high electro-magnetic fields (EMF). This procedure will focus on LTE-FDD Carrier Aggregation (Spectrum and Modulation) and OTA Control Channel to properly characterize MIMO performance. The CellAdvisor can perform additional LTE-Advance tests to further assess the radio s performance; however, for simplicity, those are not included in this document, including: 1) OTA ID Scanner to measure PCI dominance and signal quality for each carrier. 2) OTA Multipath Profile to characterize multi-rays and minimize presence of multipath power, This procedure requires LTE carrier s center frequencies and/or channel numbers with respective channel bandwidth information. Description CellAdvisor with the following functions/options: LTE - FDD analyzer option 028 LTE Advanced - FDD analyzer option 030 LTE FDD OTA analyzer option 048 GPS receiver and antenna option 010 Directional Antenna (4GHz or 6GHz) 4GHz directional antenna: - G : RF yagi antenna SMA(f), 700 to 4000 MHz, 1.85 dbd - JD (Recommended): AntennaAdvisor providing directivity and geo-location - G (Alternative): RF cable DC to 18 GHz Type-N(m) to SMA(m), 1.5 m 6GHz directional antenna: - G : RF yagi antenna SMA(f), 700 to 4000 MHz, 1.85 dbd - JD (Recommended): AntennaAdvisor providing directivity and geo-location - G (Alternative): RF cable DC to 18 GHz Type-N(m) to SMA(m), 1.5 m Part CellAdvisor Directional Antenna with AntennaAdvisor Page 2 of 15

3 2. CellAdvisor Overview The CellAdvisor is a portable instrument for Cell Site installation and maintenance covering RF, Fiber and coaxial cable testing in the field. Different CellAdvisor models are available based on functionality needed, including the base station analyzer (JD745B or JD785B), the signal analyzer (JD748B or JD788B), and RF Analyzer (JD746B or JD786B). More information can be found at: For RF testing, the CellAdvisor can also be optioned to support spectrum analysis, interference analysis, and cable, antenna and modulation analysis, covering current wideband technologies such as CDMA, WCDMA, LTE/LTE-A, LAA, and NB-IoT. Figure 1: CellAdvisor Front View Page 3 of 15

4 Figure 2: CellAdvisor Top View 3. LTE Carrier Aggregation 3.1 Test Objectives LTE-Advanced devices (including Gigabit LTE) can aggregate up to 100 MHz of spectrum using up to five 20 MHz carriers using licensed and unlicensed frequencies. Each carrier can use MIMO as 4 way transmit and receive as well as high modulation of 256 QAM to achieve even faster data rates and increase network capacity. This procedure can be used to confirm correct implementation and performance details for Carrier Aggregation and 4x4 MIMO. 3.2 Interpreting results OTA test results are subject to environment conditions, antenna placement and orientation. For example, power levels can vary 13 db with a simple 90-degree rotation of the instrument s antenna. Parallel antenna orientation yields the strongest power levels. The key to interpreting test results are in the deltas between values. They ideally should produce consistent recognizable pattern of values. For example, if there is a 13 db difference between RS0 and RS1, then rotate antenna 90 degrees the amplitudes should trade places. Optimal results are when all transmit antennas are equal in amplitude and EVM, and within time alignment requirements. This can only be witnessed when the instrument s antenna is rotated when pointed at the serving sector s antennas. 3.3 Test Setup The following procedures include the instrument s configuration and test of LTE carrier aggregation and 4x4 MIMO using OTA measurements. Page 4 of 15

5 Step Action Description 1 Power ON CellAdvisor Press and hold the ON/OFF button for 3 seconds to turn on the CellAdvisor. 2 GPS lock Attach GPS antenna SMA (male) connector to External In GPS. A GPS icon will be displayed, indicating its status: : GPS Tracking Satellites. : GPS Locked 3 RF In connection Connect the directional antenna to the RF In Spectrum Analyzer port. 4 LTE-Advance Test Mode Antenna placement should be pointed at or located within the primary coverage area for the sector under test, idealistically avoiding sector edges. Press [Mode], {Signal Analyzer}, {LTE-FDD}, [Measure],{More(1/2), {Carrier Aggregation} Page 5 of 15

6 Step Action Description Page 6 of 15

7 Step Action Description 5 LTE-Advanced Press [Measure Setup], select {CA Configuration} Configuration Each column corresponds to a component carrier (CCx) where x represents the individual carrier (1 to 5). Page 7 of 15

8 Step Action Description 6 LTE Component Press {CA Range}, enter the number of the carrier to configure (1 to 5), {Enter} Carrier Configuration Enable the carrier state by pressing {CC State} making sure On is highlighted in yellow. Select {Center Frequency} or {Channel Number} or Enter a valid value based on carrier(s) of interest using the numeric keypad with the corresponding units (e.g. Center Frequency in {MHz}) To define the carrier s bandwidth press {Bandwidth} and select the corresponding bandwidth of the carrier Configure the carrier s MIMO mode by selecting {More ½}, {MIMO}, and highlighting in yellow the corresponding MIMO operation mode of the carrier Go to step 6 LTE Component Carrier Configuration to configure the next component carrier. Page 8 of 15

9 Step Action Description The following example configuration is for 4 component carriers: 1. CC1: Center Frequency 739MHz, Bandwidth 10MHz, MIMO 2x2 2. CC2: Center Frequency 751MHz, Bandwidth 10MHz, MIMO 2x2 3. CC3: Center Frequency MHz, Bandwidth 15MHz, MIMO 4x4 4. CC4: Center Frequency 2120 MHz, Bandwidth 20MHz, MIMO 4x4 Verify the configuration of all the carriers and if correct then select [ESC] Page 9 of 15

10 3.4 LTE Advanced Modulation Analysis The following measurements verify radio s performance, decoding the transmitting radio identity (Cell IDs or PCI), and measuring the modulation quality constellation and its corresponding error vector magnitude (EVM), as well as power levels, and MIMO performance (antenna port). Step Action Description 7 Modulation Analysis of LTE Reference Signals Select [Marker], {Channel}, and with the arrow key scroll down to highlight RS0 (reference signal 0) that corresponds to the first antenna of each carrier. 8 Improve sensitivity Improve CellAdvisor s sensitivity by selecting [Amp/Scale], {Attenuation Value}, [0], {db} Page 10 of 15

11 Step Action Description And enable the internal preamplifier by selecting {Preamp} and highlighting On in yellow 9 Measurement Result The following example shows measures four component carriers: 1. CC1: Channel 5230, MIMO 2x2 2. CC2: Channel 2100, MIMO 2x2 3. CC3: Channel 1125, MIMO 2x2 4. CC4: Channel 2454, MIMO 2x2 All these carriers are transmitted from the same sector (Cell ID: 260) and show acceptable EVM values ranging from 8.29% to 19.32% Page 11 of 15

12 Step Action Description EVM Detection Mode has two different modes: - Single: best for conducted tests - Combined: best for OTA tests 3.5 LTE-Advanced Spectrum Analysis The following measurements verify radio s performance, measuring the channel power and spectral density of each component carrier. Step Action Description 10 Spectrum analysis with Channel Power To display the spectrum analysis of all the carriers, select [Trace/Display], {Display} highlighting in yellow SA (Spectrum Analysis) 3.6 LTE Advanced Over-The-Air Modulation Analysis The following over-the-air (OTA) measurements verify radio s performance, decoding the transmitting radio (Cell IDs or PCI), and measuring MIMO (antenna port) power trend and alignment (diversity), including power level, error vector magnitude and phase for each antenna. Page 12 of 15

13 The measurement of phase (degrees) between antennas (RS 0 to RS 3) relates to the physical polarity or orientation of each antenna elements. Traditional 2x antenna often uses +45º and -45º (90º) between first and second transmit element. For optimal spatial diversity one would expect no two antennas would have the same phase for 4-way transmit. Step Action Description 11 OTA Control Set the instrument in LTE-FDD analyzer mode by selecting [Mode], {Signal Channel Analyzer}, {LTE-FDD} Set the center frequency and bandwidth of the LTE carrier to be measured, by selecting [Freq/Dist], {Center Frequency}, enter the LTE carrier s center frequency using the numeric keypad in MHz, and select {MHz} If needed, improve CellAdvisor s sensitivity by selecting [Amp/Scale], {Attenuation Value}, [0], {db} And enable the internal preamplifier by selecting {Preamp} and highlighting On in yellow Page 13 of 15

14 Set the measurement for OTA Control Channel, selecting [Measure], {More ½}, {OTA}, {Control Channel} Page 14 of 15

15 4. Technical Support Technical support is provided by: Phone: GO-VIAVI ( ) options Regularly new firmware updates for the CellAdvisor are released and it is recommended to keep the instrument in the latest firmware to provide all the enhancements and bug fixes. Go to: Select the link CellAdvisor Platforms The latest firmware and software can be found on Page 15 of 15