Joint DSSS Proposal for 802.15.4g

1. Joint DSSS Proposal for 802.15.4g Merged proposal : 09-471, 09-283, 09-307 1Michael Schmidt, 2Y X Fu, 2J Shen, 2X Wang, 2Haituo Liu, 2L Li, 2Z Zhao, 2Z.F Zhao, 3Ted Myers, 3David Howard 1Atmel, 2Huawei/SIMIT/VINNO, 3On-Ramp Wireless Supported by: John Buffington, Hartman Van Wyk, Daniel Popa, Itron Roberto Aiello

2. Bands included No bandwidth limitation in bands • 780MHz (China) • 779 – 787 MHz • 868MHz (EU) • 863 – 870 MHz • 915MHz (US) • 902 – 928 MHz • 2450MHz (Intl) • 2400 – 2483.5 MHz

3. DSSS benefits • Better sensitivity increases range for hard to reach meters and challenging environments, especially in-building • Good complement to Merge FSK Proposal • Trade-off between processing gain and data rate with fixed bandwidth – long range for reduced data rate and short range for high data rate • Different data rates can be obtained by simply changing the spreading gain, with same RF design

4. Modulation • O-QPSK • Raised cosine shape r=0.8 • GMSK • Pre-coded • Equivalent to p/2 – BPSK (*) (*) for example see: Draft P802.15.3c/DF3, page 45:"a) The standard supports the use of MSK/GMSK modulations withappropriate filtering and pre-coding as an alternative way of generatingπ/2 BPSK waveform signals for the SC PHY mode."

5. PSDU Channel Code • ½ rate convolution code • Benefits • Supports long frame requirements in PAR • Provides larger gain compared to spreading as decrease data rate by ½ • Used in IS-95 and other systems • Consider interleave to improve resistance to burst interference • Interleaver • Max depth of 32 information octets • Complexity • Constraint length k=7

6. 779 – 787 MHz PHY • Chip rate = 500kcps • Channel center frequency (MHz) • 779.5, 780.5, 781.5, 782.5, 783.5, 784.5, 785.5, 786.5 • Spreading code • (4,4), (8,4), (16,4), (32,4) • PSDU coded data rate (bps) • 250k, 125k, 62.5k, 31.25k • Preamble header spreading • (32,1)

7. 863 – 870 MHz PHY • Chip rate = 200kcps • Channel center frequency (MHz) • 863.4, 873.8, 864.2, 865, 865.4, 866, 866.6, 867,2, 867.8, 868.3, 868.95 • Spreading code • (4,4), (8,4), (16,4), (32,4) • PSDU coded data rate (bps) • 100k, 50k, 25k, 12.5k • Preamble header spreading • (32,1)

8. 902–928MHz/ 2.400-2.483GHz PHY • Chip rate = 1Mcps • Channelization • 400kHz channels (*) • Spreading code • (32,4), (16,1), (32,1), (64,1) • PSDU coded data rate • 62.5k, 31.25k, 15.6k, 7.8k • Preamble header spreading • (128,1) (*) 400kHz is chosen to simplify interoperability with Merged FSK proposal. Channels are overlapping, however system will choose every forth channel, in a scheme similar to 802.11.

9. (N,1) - FEC Concatenation

10. (N,4) - FEC Concatenation

11. PPDU Format • PHR Field • 2 octets • Frame Length(11 bits) • Indicate the frame length from 0 – 2047 bytes • Compatible with PPDU Format of 802.15.4 -2006 • Date Rate Field (2 bits) • Indicate the spreading sequence to binary data of PSDU, RX adjust receive PN sequence according to this field • Parity Check Field (1 bit) • Check the PHR field

12. NB FH co-existance • DSSS channel overlaps a group of NB channels • NB must hop within DSSS channel, then both hop to next DSSS channel • DSSS receiver has ability to detect NB signals

13. Example 1.2MHz DSSS and 200KHz FH (channel spacing)