CC2420 Channel and RSSI Evaluation Nov/22/2006 Dept. of EECS, UC Berkeley C O nnect vityLab i

Contents Introduction Chipcon CC2420 Radio CC2420 RSSI Evaluation

The Comparison of Different Methods Introduction RSS values measured by COTS wireless systems are sufficiently rich in information to permit a mobile device locates itself, reliably and accurately The most important trade off is between Offline Calibration and accuracy

Continuing The Project Next Steps Last Final Conclusion Sensors Evaluation + Fingerprinting Distributed Estimation (Study, Modeling, Simulation, Implementation) Radio Map Independent Algorithm (Study, Modeling Simulation, Implementation) Tx1 Rx1 Rx2 Rx3

The Goal of this Part of the project Last Final Conclusion Become familiar with our sensors and evaluate them as much as possible Understand the behavior of RSSI in indoor environments Measure the effect of different parameters on RSSI Survey the existence of correlation in RSSI Samples and base band received signals Study the theory of indoor wireless channels (as much as it was needed) Gathering a lot of data in different situations and environment Analysis of these data Performed Works

Chipcon CC2420 Radio The Chipcon CC2420 Radio Chip Characteristics Frequency: 2.4 GHz Communication Technology: Direct Sequence Spread Spectrum Data Rate: 250 kbps Total BW: 83 MHz Output power: Programmable (Max Power = 0 dBm) The CC2420 is an IEEE compliant RF transceiver designed for low-power and low-voltage wireless applications The CC2420 Range (Indoor) : 30 m

Chipcon CC2420 Radio The Chipcon CC2420 Radio Chip Characteristics The CC2420 IF: 2 MHz 2 Sym: 4 Bits32 Chips Tc = 0.5 us Pulse Shaping: Half Sine Each Byte

The RSSI value is always averaged over 8 symbols periods (128 us) and digitized by an 8 bit ADC The Chipcon CC2420 Radio Chip Characteristics Chipcon CC2420 Radio RSSI and LQI in The CC2420 The Link Quality Indication (LQI) measurements is a characterization of the strength and/or quality of received packet RSSI and LQI values are not necessarily linked; but Low LQI Invalid RSSI

The Chipcon CC2420 Radio Chip Characteristics The values of RSSI could really affected by other people working with motes Although there is no direct interference with the Wi-Fi channels, the channel quality can be affected by the overload and thus distort some of the packets Chipcon CC2420 Radio Telos Mote Experiment, Stockholm, 2005 The Effect of Radio Interference Measurements with the same motes at the same location, same batteries show a difference up to a few dBm (from new motes to old motes) The Effect of the Motes Themselves

RMS Delay Spread CC2420 Wireless Channel Characteristics Delay Spread Channel is flat fading and a single channel filter tap is sufficient to model the channel RMS Delay Spread F=2.4 GHz Flat Fading Frequency Selective Corry Hall Corridor Chipcon CC2420 Radio

Coherence Time The maximum number of stable RSSI samples In our system, there is one RSSI sample per packet In this network configuration the RSSI rate is 26.3 sample/second per device CC2420 Wireless Channel Characteristics Chipcon CC2420 Radio

Indoor Path Loss Model Path Loss Model CC2420 RSSI Evaluation One sensor put at different distances (at the ~same time/Corridor) Test Scenario Run: RSSI_FigAvgVarHist.m at C:\ZigBeeNodes\CollectedData\Corridor_072106\Test1_QP Tx Rx

Indoor Path Loss Model Path Loss Model One sensor put at different distances (at the ~same time/Corridor) Test Scenario Conclusions - Constant offset is not -45 dBm - Path Loss almost follows the Log- Normal Model - The effect of multipath is remarkable - Something is wrong in these sensors (Interference/Sensors Board) Worth Case CC2420 RSSI Evaluation -17 dbm

Indoor Path Loss Model Path Loss Model Test Scenario One sensor put at different distances (at the ~same time/Corridor) CC2420 RSSI Evaluation

Indoor Path Loss Model Path Loss Model Test Scenario One sensor put at different distances (at the ~same time/Corridor) CC2420 RSSI Evaluation 200 RSSI

Indoor Path Loss Model Path Loss Model Test Scenario One sensor put at different distances (at the ~same time/Corridor) CC2420 RSSI Evaluation 200 RSSI

Indoor Path Loss Model Path Loss Model One sensor put at different distances (at the ~same time/Corridor) Test Scenario Conclusions -Something is wrong in these sensors - The effect of interference Worth Case Our Sensors (Outdoor) Our Sensors (Indoor) Stanford Sensors (Indoor & 100 Sensors ) Min VarMax VarAvg Var dBm Variance Test Mica Z CC2420 RSSI Evaluation

Outdoor Path Loss Model Path Loss Model Two sensors put at different distances (at the ~same time/Soccer Court) Test Scenario Conclusions - Constant offset is not -45 dBm - Path Loss almost well follows the Log-Normal Model - In the outdoor these sensors have almost same behavior - There is some offset between sensors, so calibration is necessary CC2420 RSSI Evaluation

Outdoor Path Loss Model Path Loss Model Two sensors put at different distances (at the ~same time/Soccer Court) Test Scenario CC2420 RSSI Evaluation 400 RSSI 200 RSSI

Height : 1.22 m height difference 6 dBm power difference S1: S2: S3: S4: S5: S6: dBm S1: S2: S3: S4: S5: S6: The Effect of Height The Effect of Different Parameters on RSSI Two different sets of data at two different height with 1.22 m height difference was compared (Test1 & Test2 was done at two different time/Env-Conditions) Test Scenario Test 1 AvgErrAbsMeanErr dBm Test 2 AvgErrAbsMeanErr All in dBm Reported Error for the Same Chip is 10 dBm for 1m height difference CC2420 RSSI Evaluation

The Effect of Window Test Scenario Two different sets of data at two different situations (at the same place, time and Env- condition) was compared Test AbsMeanErr (All in dBm) Window : Open/Closed0.6 dBm power difference S1: S2: S3: S4: S5: S6: Close to Window The Effect of Different Parameters on RSSI CC2420 RSSI Evaluation

The Effect of Door Test Scenario Two different sets of data at two different situations (at the same place, time and Env- condition) was compared Test AbsMeanErr (All in dBm) Door : Open/Closed1.5 dBm power difference S1: S2: S3: S4: S5: S6: Close to Door The Effect of Different Parameters on RSSI CC2420 RSSI Evaluation - Due to the need of calibration, error should be lower that this

The Effect of Different Parameters on RSSI The Effect of Lights Test Scenario Two different sets of data at two different situations (at the same place, time and Env- condition) was compared Lights : On/Off1.7 dBm power difference S1: S2: S3: S4: S5: S6: Test AbsMeanErr (All in dBm) In the order of several 0.1 dBm CC2420 RSSI Evaluation - Due to the need of calibration, error should be lower that this

Radiated pattern Vertical mounting Radiated pattern horizontal mounting Sensors (Tx) Mobile Node (Rx) Light Frame2 Light Frame BrdWal Win Dor The Effect of Antenna Direction Test Scenario Two different sets of data at two different antenna directions (at the same place, time and Env-condition) was compared The Effect of Different Parameters on RSSI Test AbsMeanErr (All in dBm) 5.5 dBm power difference CC2420 RSSI Evaluation ? - Due to the need of calibration, error should be lower that this

Power Distribution Feasibility Test Test Scenario Data Received by coordinator located under each sensor (at the time and Env- condition) was compared Conclusions - Due to the need of calibration, there is some uncertainty in these results. CC2420 RSSI Evaluation

Basic Fingerprinting Radio Map Elements By the offset compensation of sensors we can improve the performance 48 runs in different situations (Quiet and Non-Quiet) Sensors Mobile Node Light Frame2 Light Frame m 2.44 m Expected Position Estimated Position (SQR) Estimated Position (ABS) Max Error 2.44m Static Test MobileTest Estimated Position: The Effect of Different Parameters on RSSI CC2420 RSSI Evaluation Expected Position: 3 4(2) 5(6) 6(5) 2 1

NI Power samples NI RSSI Evaluation

Thank You The End

Box Whisker Plot (N(0,sigma))