WG9 Frequency Banding Analysis

ANALYSIS OF THE DELTA HEARING AID IMMUNITY DATA AND THE PROPOSED C63.19 FREQUENCY BANDING: 

ANALYSIS OF THE DELTA HEARING AID IMMUNITY DATA AND THE PROPOSED C63.19 FREQUENCY BANDING

BYSTANDER: 3 V/m, 2 V/m: 

BYSTANDER: 3 V/m, 2 V/m 1. Difference Between Bands 2. Overall Immunity Improvement (Over 30 dB!!!)

PROPOSAL: 10 dB RELAXATION FOR WD ON LOW BAND (< 960 MHz): 

PROPOSAL: 10 dB RELAXATION FOR WD ON LOW BAND (< 960 MHz) 10 dB relaxation (Up to 354.8 V/m) for Wireless Devices needs to consider: 1.) Difference Between Frequency Bands (850 MHz vs. 1900 MHz) 2.) Field Strength Hearing Aid was Tested Bystander:3 V/m and 2 V/m User: 75 V/m and 50 V/m Wireless Device: M1 (354.8 V/m) and M3 (112.2 V/m) 3.) Overall Immunity Improvement (IRIL) and Measurement 1kHz, 80% AM GTEM (Far Field) Near Field

HEARING AID IMMUNITY TEST: C63.19 vs. IEC 60118-13: 

HEARING AID IMMUNITY TEST: C63.19 vs. IEC 60118-13 C63.19 Method 1: Near Field At 900 MHz Max RF + 3 dB, 1kHz 80% AM At 1800 MHz 1W with 1kHz 80% AM. Method 2: WB-GTEM At 800-950 MHz Increase Field Strength to Produce 55 dB IRIL in HA At 1600 – 2500 MHz Increase Field Strength to Produce 55 dB IRIL in HA IEC60118-13 GTEM only 800-960 MHz Bystander: 3 V/m User: 75 V/m 1400-2000 MHz Bystander: 2 V/m User: 50 V/m

WIRELESS DEVICE FIELD STRENGTHS: 

WIRELESS DEVICE FIELD STRENGTHS 1900 MHz Wireless Devices are qualifying as M3 63.1 V/m to 112.2 V/m w/ AWF (-5) 47.3 V/m to 84.1 V/m 850 MHz Wireless Devices are qualifying at M1 199.5 V/m to 354.8 V/m w/ AWF (-5) 149.6 V/m to 266.1 V/m

BANDING DISCUSSION: 

BANDING DISCUSSION Recent Measurements of Banding: Several Banding Tests performed in the Cingular Wireless lab Real World Testing at 2005 SHHH Convention DELTA Hearing Aid study Banding has been proposed in C63.19 rd 3.8 At C63 meeting in Irvine, CA: Discussion of 10 dB was debated “Additional data needed to substantiate 10 dB” Today will present another analysis of DELTA data for 2003, 2004, 2005 regarding banding. Introduce the Predicted IRIL/OIRIL for Wireless Device Field Strengths based on IEC USER (75 V/m, 50 V/m) Field Strengths measured in the DELTA HA Study.

ELECTROMAGNETIC RESPONSE OF HEARING AIDS: 

ELECTROMAGNETIC RESPONSE OF HEARING AIDS The GTEM testing at 75 and 50 V/m is not representative of real world RF field strengths of Wireless Devices and the Interference Noise Power introduced into Hearing Aids. What is needed is a way to predict Hearing Aid performance at Wireless Device field strengths.

IRIL MODEL: 

IRIL MODEL Model to Predict IRIL is based on EMC Paper from Robert Schlegel and Hank Grant of OU: IRIL (Interference Related Input Level) Square Law Effect OIRIL (Overall Interference Related Input Level) Wireless Device Modulation

INPUT REFERENCED INTERFERENCE LEVEL (IRIL): 

INPUT REFERENCED INTERFERENCE LEVEL (IRIL) Single frequency is used for determining Hearing Aid Immunity: 1kHz Sinusoidal 80% amplitude-modulated RF test Signal The IRIL is then calculated as:

INPUT REFERENCED INTERFERENCE SPECTRUM (IRIS) CONCEPT: 

INPUT REFERENCED INTERFERENCE SPECTRUM (IRIS) CONCEPT IRIS represents the equivalent acoustic input for the entire spectrum of interference for a pulsed RF waveform (Wireless Device). The Sound Energy in this IRIS may be accumulated to provide an OVERALL INPUT REFERENCED INTERFERENCE LEVEL (OIRIL in decibels SPL), an un-weighted (linear) summation (in pressure units) that represents the interference from a specific wireless phone. Reference: Modeling the Electromagnetic Response of Hearing Aids to Digital Wireless Phones. Schlegel & Grant, IEEE TRANSACTIONS ON ELECTROMAGNETIC COMPATIBILITY. VOL. 42, NOVEMBER 2000.

IRIL to OIRIL CONVERSION FACTORS: 

IRIL to OIRIL CONVERSION FACTORS For GSM = 10.68, TDMA = 7.60 dB Example: 1 V/m Sine Wave Carrier, 80% AM Modulated will produce an IRIL, which is 10.68 dB (SPL) HIGHER than the OIRIL produced by a 1 V/m GSM pulse.

Slide12: 

80% AM Sine Wave GSM Pulse (1/3 duty Cycle) Hearing Aid Hearing Aid Output Response

MODEL DEVELOPMENT: PREDICT OIRIL FROM AN IRIL IMMUNITY MEASUREMENT: 

MODEL DEVELOPMENT: PREDICT OIRIL FROM AN IRIL IMMUNITY MEASUREMENT 3 Steps: 1.) Determination of the field strength needed to produce a specific IRIL using 1 kHz 80% AM carrier. 2.) Determination of the field strength around the ear piece of the wireless device and a corresponding prediction of the IRIL that would be produced by that field strength. 3.) A computational adjustment to compensate for the difference between IRIL and OIRIL for the specific wireless device technology in use.

SQUARE LAW EFFECT: 

SQUARE LAW EFFECT There is a 2:1 multiplication factor when converting from RF field strength in decibel units to sound pressure level (SPL) in decibels. = IRIL of Hearing Aid at Reference Field Strength = Reference Field Strength at which the Hearing Aid IRIL was measured = Desired Field Strength Limits, Lower Bound is acoustic ambient background noise Upper Bound is saturation of the Hearing Aid amplifier.

EXAMPLE OF PREDICTED IRIL AND OIRIL: 

EXAMPLE OF PREDICTED IRIL AND OIRIL = 55 dB SPL = 100 V/m = 40 dB V/m What is IRIL at = 200 V/m = 46 dB V/m? = 55 + 2(46 – 40) in dB SPL = 67 dB SPL = 67 – 10.68 in dB SPL = 56.32 dB SPL

DELTA HA IMMUNITY ANALYSIS: FREQUENCY BANDING: 

DELTA HA IMMUNITY ANALYSIS: FREQUENCY BANDING Since the DELTA data was NOT tested at the Field Strengths of GSM 850 / 1900 Wireless Device, this IRIL Model is used to predict performance at a different Field Strength. 10 dB Analysis How would the 850 vs. 1900 MHz band compare at 354.8 V/m and 112.2 V/m? 850 MHz is being proposed 354.8 V/m 1900 MHz is allowed 112.2 V/m

BACKGROUND: DELTA HEARING AID IMMUNITY DATA: 

BACKGROUND: DELTA HEARING AID IMMUNITY DATA DELTA data spans from 1997 to 2005. DELTA chart presented early only compares Bystander Compatibility (3 V/m, 2 V/m). Field Strength of Bystander is not typical of a wireless device (>200 V/m, >90 V/m). NOTE: Immunity Based on 1kHz, 80% AM CW signal not GSM Pulsed (217).

DELTA: FIELD STRENGTHS USED FOR IRIL TESTING : 

DELTA: FIELD STRENGTHS USED FOR IRIL TESTING NOTE: the higher field strengths used for the Low Band. (indicates higher immunity) IEC 60118: USER COMPATIBLE FIELD STRENGTH (All HA Samples tested at these field strengths for that year)

DELTA OBSERVATION: 

DELTA OBSERVATION In reviewing the yearly DELTA data, Between 1997 thru 2002, there were some Hearing Aids where the measurement of Acoustic Output was recorded as being < Value (Ex. <55) or below threshold. For some years this would have been significant number of samples. There were no Hearing Aids with Acoustic Output recorded as below threshold in the years 2003 – 2005. Based on this, the banding analysis was analyzed for the 2003 - 2005 years.

HEARING AIDS WITH MEASUREMENT SAMPLES RECORDED AS BELOW THRESHOLD: 

HEARING AIDS WITH MEASUREMENT SAMPLES RECORDED AS BELOW THRESHOLD In analyzing the DELTA data for the banding analysis it was chosen to use the 2003, 2004, 2005 data for the predicted OIRIL response.

DELTA DATA: USER FIELD STRENGTH (75 / 50 V/m) BANDING DIFFERENCE2003 - 2005: 

DELTA DATA: USER FIELD STRENGTH (75 / 50 V/m) BANDING DIFFERENCE 2003 - 2005 Using the highest field strength (As tested for the low and high band in the DELTA Data) the Frequency Banding difference is:

2003 BANDING STATISTICS: 75 V/m (LOW BAND) vs. 50 V/m (HIGH BAND): 

2003 BANDING STATISTICS: 75 V/m (LOW BAND) vs. 50 V/m (HIGH BAND)

2004 BANDING STATISTICS: 75 V/m (LOW BAND) vs. 50 V/m (HIGH BAND): 

2004 BANDING STATISTICS: 75 V/m (LOW BAND) vs. 50 V/m (HIGH BAND)

2005 BANDING STATISTICS: 75 V/m (LOW BAND) vs. 50 V/m (HIGH BAND): 

2005 BANDING STATISTICS: 75 V/m (LOW BAND) vs. 50 V/m (HIGH BAND)

BANDING COMMENT: 

BANDING COMMENT If we stopped our analysis here we would say the 10+ dB of immunity has been demonstrated in the Hearing Aid between the Low and High bands. Based on the square law effect of the Hearing Aid this would say the Wireless Device in the Low band (<960 MHz) could be relaxed 5-6 dB. Would the banding be different if the Hearing Aid was tested at field strengths typical of dual band (850/1900) Wireless Devices? What about the modulation used by the wireless device? Would it matter? Would the Wireless Device Field Strength (real world) + Hearing Aid immunity result in an Overall IRIL of less than 55 dB SPL to the HA user?

BANDING COMMENT (cont’d.): 

BANDING COMMENT (cont’d.) It was chosen to use the OU IRIL Model in predicting what the DELTA HA response to field strengths for the Worst Case wireless device corresponding to M1 (M3 proposed) at 850 (354.8 V/m) and M3 at 1900 (112.2 V/m) would result. The next step is to account for GSM Modulation on the Hearing Aid and what the Overall IRIL (OIRIL) is in dB SPL.

BANDING COMMENT (cont’d.): 

BANDING COMMENT (cont’d.) The Overall IRIL (OIRIL) is what was measured for the Cingular Wireless Lab Test1 in Austin and was confirmed in real world testing at the 2005 SHHH convention. Wireless Device (2 W Low band / 1 W High Band), NOT an 1kHz, 80% AM Modulation, was coupled with a Hearing Aid If re-banding in the C63.19 Standard is allowed for 850 MHz wireless devices, that is to be rated M3 for worst case (354.8 V/m), how would that compare to 1900 MHz wireless devices which are allowed 112.1 V/m for GSM (without the additional AWF penalty)? 10 dB Relaxation: For Wireless Devices Operating <960 MHz to have an max E-field of 354.8 V/m. 1 Note: In comparing the Frequency Banding, the Hearing Aid gain was not subtracted out of the measured Hearing Aid response as we did not have the gain profile for each hearing aid.

DATA ANALYSIS FLOW: 

Is 850 MHz 2W WD with 10 dB Relaxation (354.8 V/m M rating) worse than the response 1900 MHz 1W WD (112.8 V/m M rating) to Hearing Aids using the DELTA 2003 – 2005 Hearing Aid IRIL data? DATA ANALYSIS FLOW

2003: 850 BETTER THAN 1900 UP TO 55 dB SPL: 

2003: 850 BETTER THAN 1900 UP TO 55 dB SPL More Hearing Aids have a <55 dB SPL using 850 MHz than 1900 MHz PROPOSED 850MHz Wireless Device w/ 10 dB Relaxation!!! ALLOWED TODAY 1900 MHz Wireless Device M3.

2004: 850 BETTER THAN 1900 UP TO 55 dB SPL: 

2004: 850 BETTER THAN 1900 UP TO 55 dB SPL More Hearing Aids have a <55 dB SPL using 850 MHz than 1900 MHz PROPOSED 850MHz Wireless Device w/ 10 dB Relaxation!!! ALLOWED TODAY 1900 MHz Wireless Device M3.

2005: 850 BETTER THAN 1900 UP TO 55 dB SPL: 

2005: 850 BETTER THAN 1900 UP TO 55 dB SPL More Hearing Aids have a <55 dB SPL using 850 MHz than 1900 MHz PROPOSED 850MHz Wireless Device w/ 10 dB Relaxation!!! ALLOWED TODAY 1900 MHz Wireless Device M3.

OIRIL YEARLY SUMMARY: 2003 -2005 DELTA DATA: 

OIRIL YEARLY SUMMARY: 2003 -2005 DELTA DATA Proposed 10 dB (354 V/m) Relaxation for 850 MHz Wireless Devices Allowed Today M3 Rated (112 V/m) for 1900 MHz Wireless Devices

RESULTS: 

RESULTS 2003 – 2005 Totals LOW BAND (<960 MHz): 167 Hearing Aids with <= 55 dB SPL HIGH BAND (>1400 MHz): 127 Hearing Aids with <= 55 dB SPL Looking closely at the curves, we see that Year over Year, MORE HEARING AIDS would have a lower Overall IRIL (up to 55 dB SPL) on the 850 Band than the 1900 MHz band (36 vs. 24, 75 vs. 63, 56 vs. 40). This matches results seen from the Previous Lab Testing and User Testing at 2005 SHHH Convention.

SUMMARY: 

SUMMARY With a 10 dB Relaxation and based on the DELTA 2003 - 2005 Hearing Aid Improvements, More Hearing Aid Consumers using a wireless device with a 10 dB (354.8 V/m) relaxation on the 850 MHz Low band would still have an overall better experience (<= 55 dB SPL) than the 1900 MHz High Band (112.8 V/m). Allowing the 10 dB shift puts the 850 MHz wireless device on level with what the 1900 MHz wireless devices are allowed today to consumers Based on the Frequency Banding Effect on Hearing Aid immunity and overall IRIL improvements as reported in the DELTA data (2003-2005).

CONCLUSIONS: 

CONCLUSIONS Comments Next Steps. Thank You.