Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)
Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)
description
Transcript of Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)
Aug. 2004
Liang Li, VSZJSlide 1
doc.: IEEE 802.15-04-0314-02-004b
Submission
Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [Enhanced OQPSK Modulation with Orthogonal DSSS Sequences]Date Submitted: [Aug 2004]Source: [Liang Li, Yafei Tian, Liang Zhang, Chenyang Yang, Zhijian Hu, ]
Company: [WXZJ Inc/Helicomm Inc]Address: [Building D, No.2, Shangdi XinXi Lu, Beijing, China 100085 ]Voice:[], E-Mail:[[email protected]]
Re: [ IEEE 802.15.4 ]
Abstract: [This contribution proposes an updated PHY for TG4b.]
Purpose: [To encourage discussion.]
Notice: This document has been prepared to assist the IEEE P802.15b. 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.
Aug. 2004
Liang Li, VSZJSlide 2
doc.: IEEE 802.15-04-0314-02-004b
Submission
Proposal for IEEE802.15.4b
• A new PHY for low-rate WPAN that employs the MSK modulation scheme with new DSSS sequences:– Keeps the present OQPSK modulation. – New DSSS sequences: 16 sequences for 4-bit
mapping.– Data rate
• >=125Kbps (915MHz Band)
• >=100Kbps (868MHz Bnad)
Aug. 2004
Liang Li, VSZJSlide 3
doc.: IEEE 802.15-04-0314-02-004b
Submission
Summary of ProposalCh #0868MHz band
Ch #1-10906 – 924 MHz band
Bandwidth 600 kHz 2 MHz
Recommended Code Set 16-chip code set (1/4 bit/chip)
16-chip code set (1/4 bit/chip)
Chip rate 400kcps 500cps
Pulse shape Half-sine pulse shape Half-sine pulse shape
Modulation O-QPSK O-QPSK
Data rate >=100 kbps >=125 kbps
Aug. 2004
Liang Li, VSZJSlide 4
doc.: IEEE 802.15-04-0314-02-004b
Submission
Spectra (915MHz Band)
-2 -1 0 1 2 3 4-55
-50
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
f-fc (MHz)
PS
D (
dBm
/100
KH
z) f
or 0
dBm
Tx
pow
er
Aug. 2004
Liang Li, VSZJSlide 5
doc.: IEEE 802.15-04-0314-02-004b
Submission
Spectra (868MHz Band)
-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1-55
-50
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
f-fc (MHz)
PS
D (
dBm
/100
KH
z) f
or 0
dBm
Tx
pow
er
Aug. 2004
Liang Li, VSZJSlide 6
doc.: IEEE 802.15-04-0314-02-004b
Submission
Key Features of Our Proposal• Improved DSSS sequences:
– 16 DSSS sequences for 4-bit mapping.– Each sequence consists of 16 chips instead of
32, which results in ¼ chip rate • (500Kcps) for 125kbps data rate.• (400Kcps) for 100Kps data rate
– Better orthogonal characteristics between the modulated symbols and improving the decoding performance.
Aug. 2004
Liang Li, VSZJSlide 7
doc.: IEEE 802.15-04-0314-02-004b
Submission
Key Features of Our Proposal (cont.)
• Backward compatible:– The same modulation scheme used for the
transceiver on 915 MHz and 868 MHzOQPSK + Half-sine pulse shape
– Keeps constant envelop and continuous phase.
Aug. 2004
Liang Li, VSZJSlide 8
doc.: IEEE 802.15-04-0314-02-004b
Submission
Key Features of Our Proposal (cont.)
• Lower RF requirements:– At 915MHz US Band:
• 2MHz channel separation, Total 10 channels.
• 750KHz main lobe
– At 868 MHz European Band:• 600 kHz channel channel.
• 400KHz main lobe
• Lower out-of-band emission• > 30dB depression on first lobe (915MHzband)
• >28dB depression on first lobe (868MHz bnad)
Aug. 2004
Liang Li, VSZJSlide 9
doc.: IEEE 802.15-04-0314-02-004b
Submission
Generating SequenceDecimal Symbol
Binary Symbol Chip Values
0 0 0 0 0 0 0 1 1 0 1 0 0 0 1 0 0 0 1 0 0
1 1 0 0 0 0 1 1 0 0 0 0 1 0 0 0 1 0 0 0 1
2 0 1 0 0 0 0 0 0 0 1 1 1 0 1 1 1 0 1 1 1
3 1 1 0 0 0 1 0 1 0 0 1 0 0 0 1 0 0 0 1 0
4 0 0 1 0 0 0 1 1 1 0 1 1 0 1 0 0 1 0 1 1
5 1 0 1 0 0 1 1 0 1 1 1 0 0 0 0 1 1 1 1 0
6 1 1 1 0 0 0 0 0 1 0 0 0 0 1 1 1 1 0 0 0
7 0 1 1 1 0 1 0 1 1 1 0 1 0 0 1 0 1 1 0 1
8 0 0 0 1 0 0 1 1 0 1 0 0 1 0 1 1 1 0 1 1
9 1 0 0 1 0 1 1 0 0 0 0 1 1 1 1 0 1 1 1 0
10 0 1 0 1 0 0 0 0 0 1 1 1 1 0 0 0 1 0 0 0
11 1 1 0 1 0 1 0 1 0 0 1 0 1 1 0 1 1 1 0 1
12 0 0 1 1 0 0 1 1 1 0 1 1 1 0 1 1 0 1 0 0
13 1 0 1 1 0 1 1 0 1 1 1 0 1 1 1 0 0 0 0 1
14 0 1 1 1 0 0 0 0 1 0 0 0 1 0 0 0 0 1 1 1
15 1 1 1 1 0 1 0 1 1 1 0 1 1 1 0 1 0 0 1 0
Aug. 2004
Liang Li, VSZJSlide 10
doc.: IEEE 802.15-04-0314-02-004b
Submission
Modulation
The case for symbol 0
Aug. 2004
Liang Li, VSZJSlide 11
doc.: IEEE 802.15-04-0314-02-004b
Submission
Orthogonal Characteristic
With OQPSK modulation, half-sine pulse shaping and a sampling rate of 500KHz, after spreading and modulation, the symbol “0” can be written as:
Tjjjjjjjj 111111110 s
Similarly, we can get all 16 symbols s0, s1, … s15, where
)15,,0,( 0
16
nmnm
nmn
Hm ss
Sampled at the chip rate, the transmitted symbols keep their mutual orthogonality.
Aug. 2004
Liang Li, VSZJSlide 12
doc.: IEEE 802.15-04-0314-02-004b
Submission
Performance
NC-16FSK is the results of the non-coherent demodulation of 16-FSK which uses envelope detection.
Aug. 2004
Liang Li, VSZJSlide 13
doc.: IEEE 802.15-04-0314-02-004b
Submission
Performance (cont.)
Environment SNR @1e-2 PER
AWGN 4 dB
RMS Delay Spread 100ns 22 dB
RMS Delay Spread 200ns 23 dB
10,000 packets are transmitted.
Aug. 2004
Liang Li, VSZJSlide 14
doc.: IEEE 802.15-04-0314-02-004b
Submission
Remarks
– Simulation shows the decoder having a 0.5 to 1dB improvement in BER vs. Eb/No performance over 802.15.4.
– Effective bandwidth 0.25 bit/Hz.– Lower calculation complexity– Lower requirements on RF filter– Possible to implement a full-rate (250 kbps) system
using 1M chip rate without adding any complexity and still conform to the spectrum specifications with a 2MHz channel bandwidth.