Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [TG4f FM Deviation Tolerance] Date Submitted: [12 March, 2011] Source: [Paul Gorday, Fred Martin] Company [Sunrise Micro Devices] Address [9181 Glades Road, Suite 125, Boca Raton, Florida, USA] Voice:[561-451-4100], E-Mail:[paul@sunrisemicro.com, martin@sunrisemicro.com] Re: [802.15.4f comment resolution] Abstract: [Proposed FM deviation tolerance for 802.15.4f 433 MHz PHY] Purpose: [To be considered during 802.15.4f standard development process.] Notice: This document has been prepared to assist the IEEE P802.15. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P802.15. Paul Gorday, Sunrise Micro Devices

2. TG4f FM Deviation Tolerance Paul Gorday, Sunrise Micro Devices

3. MSK Modulation • 1MSK is binary continuous-phase FSK with modulation index h=0.5 • FM deviation = Δf = 0.25Rb (Rb = bit rate = 1/Tb) Data Waveform 1 Tb 3Tb 4Tb 5Tb 6Tb 7Tb 8Tb 2Tb t -1 Instantaneous Frequency fc + Δf Tb 3Tb 4Tb 5Tb 6Tb 7Tb 8Tb 2Tb t fc - Δf [1] John G. Proakis, Digital Communications, 3rd Ed., McGraw-Hill, New York, 1995. Paul Gorday, Sunrise Micro Devices

4. MSK Implementation • Numerous implementation methods exist for FM • Low-cost, low-power options are desired for 802.15.4f • Examples include • Direct modulation of PLL reference oscillator • Frac-N synthesizer modulation FM Modulated Carrier Phase Det. Loop Filter OSC VCO Ref. Osc. Modulation Loop Divider Frac-N Modulation Paul Gorday, Sunrise Micro Devices

5. PLL Modulation Effects • The PLL acts like a data filter (filtered MSK) → rounded bit edges, overshoot • PLL response is constrained by other performance criteria (component size, phase noise, spurs, settling time). • Practical PLL configuration results in 25-30% overshoot. Rb=250 kbps Rb=31.25 kbps PLL settings: 400 kHz unity gain frequency, 7x ratio of loop filter pole/zero to unity gain frequency Paul Gorday, Sunrise Micro Devices

6. Packet Error Rate (PER) • 31.25 kbps: Negligible effect on PER • 250 kbps: PER slightly improved due to deviation overshoot Rb= 250 kbps Paul Gorday, Sunrise Micro Devices

7. Spectrum • 31.25 kbps: Negligible effect on spectrum • 250 kbps: Main lobe slightly wider, reduced side lobes (filtered MSK) Rb=250 kbps Paul Gorday, Sunrise Micro Devices

8. Recommendations • Low cost and low power are main drivers for 802.15.4f • To minimize cost and power, modulation specifications should be the least restrictive specifications that allow functional requirements of the standard to be met • Transient deviation errors shown here don’t adversely affect performance • Peak deviation tolerance spec of 30% allows low-cost, low-power implementation option • Can also specify a tighter “steady state” deviation tolerance when data contains long pattern of “1’s” or “0’s”. Paul Gorday, Sunrise Micro Devices