RF Channel Characterization with Multiple Antenna Systems for LTE

Transcription

1 RF Channel Characterization with Multiple Antenna Systems for LTE Leonhard Korowajczuk CEO/CTO CelPlan Technologies /18/2012 Copyright CelPlan Technologies, Inc. 1

2 CelPlan Technologies Planning, Design and Optimization Software for all applications and network technologies Network planning, design an optimization services Turnkey deployment of dedicated wireless networks Specialized High Level Consulting Technical Team Building Technology Training Business Case Preparation CelPlan has design and optimized hundreds of networks of all main technologies around the world 9/18/2012 Copyright CelPlan Technologies, Inc. 2

3 Leonhard Korowajczuk 45 years R&D, engineering and manufacturing experience in the telecom field SESA RIO, STC, BTM CPqD (Telecom R&D Center) Elebra/ Alcatel CEO and CTO CelPlan Technologies Holds 13 patents Published Books Designing cdma2000 Systems published by Wiley in pages, available in hard cover, e-book and Kindle LTE, WiMAX and WLAN Network Design, Optimization and Performance Analysis published by Wiley (June 2011)- 750 pages, available in hard cover, e- book and Kindle Books in Preparation: LTE, WiMAX and WLAN Network Design, Optimization and Performance Analysis- second edition (Wiley) Network Video: Private and Public Safety Applications (Wiley) Multi-technology Networks: from GSM to LTE (Wiley) Backhaul Network Design (Wiley) Smart Grids Network Design 9/18/2012 Copyright CelPlan Technologies, Inc. 3

4 Questions that do not have replies today What is network s RF channel response? How wide and long is the multipath fading? How many multipath are being received? How un-correlated are cell antennas? How to adjust the antennas for maximum un-correlation? What is the channel load and how are the resources distributed? How should the network parameters be optimized? 9/18/2012 Copyright CelPlan Technologies, Inc. 4

5 CelSDRx Universal Software Defined Receiver (SDRx) Captures up to 100 MHz of spectrum from 100 MHz to 18 GHz Digitizes signal at 125 Msps and provides I and Q components Digitally extracts information for any digital technology: LTE, WiMAX, HSPA, UMTS, GSM Implemented for LTE Performs Symbol synchronization Frame Synchronization Sub-Channel Equalization Bandwidth and frame number determination Detects RF Channel Response in time and frequency Displays fading amplitude, band and duration Channel Traffic load Received signal coherence from different antennas Received signal coherence to different antennas GPS data geo-referencing, allowing drive tests Ideal to plan network parameters Ideal to scan competitive networks Patents applied 9/18/2012 Copyright CelPlan Technologies, Inc. 5

6 CelSDRx Specifications Frequency coverage: 100 MHz to 18 GHz Instantaneous Bandwidth: 100 MHz Displayed Average Noise Level: MHz MHz MHz Maximum RF input: +10 dbm Non-input related spurs: < -100 dbm Maximum RF gain: 20 db IF gain: -10 to +30 db in 1 db steps Power Supply +12 VDC 9/18/2012 Copyright CelPlan Technologies, Inc. 6

7 LTE Downlink Frame Subcarrier spacing: 15 khz Frame Duration: 10 ms Sub-Frame duration: 1ms Slot Duration: 0.5 ms Slot: 6 or 7 Symbols 9/18/2012 Copyright CelPlan Technologies, Inc. 7

8 LTE Downlink Frame Detail PSS (Primary Synchronization Signal) SSS (secondary Synchronization Signal) PBCH (Physical Broadcast Channel RS (Reference Signals) Control Channels Data Channels Resource Element 9/18/2012 Copyright CelPlan Technologies, Inc. 8

9 Reference Signals Each antenna transmits its own reference signals (RS) An antenna does not transmit in the slots dedicated to the other antenna symbols The exact position of the RS for an antenna depends on the CellID Extended CP 2 Slots (1 ms) Odd Slot (0.5 ms) Even Slot (0.5 ms) 12 sub-carriers Normal CP Symbol 12 sub-carriers Antenna Port 0 Antenna Port 2 Antenna Port 1 Antenna Port 3 9/18/2012 Copyright CelPlan Technologies, Inc. 9

10 Resource Element and Resource Block A Resource Element (RE) is defined by one sub-carrier and 1 symbol A Resource Block (RB) is defined by 12 consecutive sub-carriers and 1 slot duration Short Cyclic Prefix: 12 sub-carriers x 7 symbols: 84 RE Long Cyclic Prefix: 12 sub-carriers x 6 symbols: 72 RE The smallest allocation for data transmission is one TTI (Transmission Time Interval): 1 ms (1 sub-frame/ 2 slots/2 RB) Several RE are reserved for Reference Signals and Control Channels 12 sub-carriers 12 sub-carriers 7 symbols 0.5 ms 1 slot 6 symbols 0.5 ms 1 slot 9/18/2012 Copyright CelPlan Technologies, Inc. 10

11 LTE Measurement Capabilities Bandwidth: MHz FDD and TDD Measurements PSS Power/ Quality SSS Power/Quality Physical Layer Cell Identity Group MIB detection (Bandwidth and Number of Antennas) Reference Signal Received Power/Quality (RSRP) Wideband Spectral Display with Marker Functions Power vs. Time vs. Frequency Average RSSI Channel Impulse Response and Power Delay Profile Number of Multipath Components RF Channels Response Antenna Correlation Measurements are time stamped and Geo-referenced 9/18/2012 Copyright CelPlan Technologies, Inc. 11

12 LTE Signal Capture Example Band: 700 MHz Verizon (Block C) Channel Bandwidth: 10 MHz Total Sub-carriers: 667 Used Sub-carriers: 600 9/18/2012 Copyright CelPlan Technologies, Inc. 12

13 Steps Set frequency and capture bandwidth Capture 200 ms Extract baseband signal I and Q Apply FFT Search for PSS Establish part of cell ID Search for SSS Establish Cell ID Synchronize frame start and symbols Generate RS Detect RS Obtain RF channel response Calculate RF channel response for RS signals Interpolate RF channel response for other symbols Adjust all symbol values Extract PBCH values MIB Channel bandwidth, number of antennas, cyclic prefix Frame number Obtain frame map Correlate frames 9/18/2012 Copyright CelPlan Technologies, Inc. 13

14 Average Sub-carrier Power per Frame (dbm) 9/18/2012 Copyright CelPlan Technologies, Inc. 14

15 Average OFDM Symbol Power per Band (dbm) 9/18/2012 Copyright CelPlan Technologies, Inc. 15

16 Impulse Response 9/18/2012 Copyright CelPlan Technologies, Inc. 16

17 Measured Power per Resource Element (dbm) 9/18/2012 Copyright CelPlan Technologies, Inc. 17

18 RF Channel Response (top view) 9/18/2012 Copyright CelPlan Technologies, Inc. 18

19 RF Channel Response (time zoom) 9/18/2012 Copyright CelPlan Technologies, Inc. 19

20 RF Channel Response (frequency and time zoom) 9/18/2012 Copyright CelPlan Technologies, Inc. 20

21 RF Channel Response (3D detail) 9/18/2012 Copyright CelPlan Technologies, Inc. 21

22 Adjusted Power per Resource Element (dbm) 9/18/2012 Copyright CelPlan Technologies, Inc. 22

23 Traffic view Traffic allocation can be visualized per frame 9/18/2012 Copyright CelPlan Technologies, Inc. 23

24 Correlation Correlation is considered as the sympathetic movement of two or more variables Pearson s Product-Moment Correlation Coefficient The correlation coefficient varies between +1 and -1 Positive Correlation: movement is in the same direction Negative Correlation: movement is in the opposite direction Reference signals transmitted by two antennas can be used to establish the channel response The correlation coefficient for the two channel responses can then be calculated 9/18/2012 Copyright CelPlan Technologies, Inc. 24

25 Correlation between antennas Correlation index between two antennas CI=0.42 9/18/2012 Copyright CelPlan Technologies, Inc. 25

26 Antenna Correlation Drive Antenna correlation variation 9/18/2012 Copyright CelPlan Technologies, Inc. 26

27 Conclusion CelSDRx promises to be an important tool to evaluate the RF channel performance and tune systems with multiple antennas. It will increase network throughput and reduce interference A side benefit is the ability of evaluating traffic loads The flexibility of Software Defined Receivers is essential for the complex digital systems being deployed 9/18/2012 Copyright CelPlan Technologies, Inc. 27