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Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Enhanced DSSS Code Sequence with Offset QPSK for 802.15.4b High Rate Alt-PHY ] Date Submitted: [13 Jan, 2004]

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slide1

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

Submission Title: [Enhanced DSSS Code Sequence with Offset QPSK for 802.15.4b High Rate Alt-PHY]

Date Submitted: [13 Jan, 2004]

Source: [Liang Zhang, Hongyu Gu, Liang Li, Yafei Tian, Chenyang Yang, Zhijian Hu, Yong Gu] Company: [WXZJ]

Address: [2 Xinxi St, Building D, Haidian District, Beijing, China 100085 ]

Voice:[86-10-139-11895301], E-Mail:[liang_1@yahoo.com]

Re: [Response to the call for proposal of IEEE 802.15.4b]

Abstract: [This presentation compares all proposals for the IEEE802.15.4b PHY standard.]

Purpose: [Proposal to IEEE 802.15.4b Task Group]

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.

Liang Li, WXZJ

slide2

Motivation

It is desirable choose a code sequences that will lead to efficient transmission and low implementation complexity. In particular, it should:

  • Avoid spikes in frequency spectrum
  • Simplify correlation operations
  • Enable simple frequency offset and DC compensation

Liang Li, WXZJ

current dsss sequence e 16 has non zero dc value

Decimal 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

Current DSSS Sequence E16 has non-zero DC value ….

DC values

Total DC values = -16

  • Source doc.: IEEE 802.15-04-0314-02-004b

Liang Li, WXZJ

slide4

Motivation

As such, it is desirable that the code sequences have the following properties:

  • All sequences contain an equal number of ones and zeros in total
  • All sequences contain an equal number of ones and zeros in the even numbered chips (I phase)
  • All sequences contain an equal number of ones and zeros in the odd numbered chips (Q phase)
  • Total phase rotation in I / Q plane accumulates to 0 degree over the complete symbol
  • The first 8 symbols are shifted versions of each other
  • The last 8 symbols have inverted odd numbered chips (Q phase); when compared to the 8 first symbols, have the exact inverted baseband phase

Liang Li, WXZJ

the features of w16 sequences
The Features of W16 Sequences
  • lHave the same features of the Code sequence in 802.15.4
    • 1.Same 0 and 1 in preamble sequence;
    • 2. The first chip is not always 0 or 1;
    • 3. Total DC value is 0, though not always 0 in every sequences;
    • 4. The phase comes back to 0 after one symbol period;
  • lMaintained characteristic from E16 orthogonal sequences:
    • 1.Orthogonal characteristic introduced by Walsh conversion;
    • 2. More familiar performance to that of E16 orthogonal sequences;
    • 3. The low complex correlation decoder can also be implemented;

Liang Li, WXZJ

psd of tx signal with w16 code before and after tx filter
PSD of TX signal with W16 code before and after Tx filter

Left: PSD of Tx signal before TX filter

Right: PSD of Tx Signal After TX filter.

r=0.6 FIR filter for 2x over sampling rate

Liang Li, WXZJ

cross correlation of received signal 2x over sampling rate with w16 left and en cobi16 right
Cross-correlation of received Signal (2x Over Sampling Rate) with W16 (left) and En-Cobi16 (Right)

Liang Li, WXZJ

awgn non coherent
AWGN (Non-coherent)

Left: PER without TX filter, Right: PER with TX filter.

2x Tx/Rx Over Sampling Rate, 4x Channel Over Sampling Rate, No Sync Error,

No Frame Detection, 20 Octets per PPDUs, 1e4 Monte Carlo Simulation,

Without Filter and Power Amplifier

Liang Li, WXZJ

awgn ideal sync vs correlation sync
AWGN: Ideal Sync. vs. Correlation Sync.

PER in AWGN Channel with a 7-tap FIR filter:

2x Tx/Rx Over Sampling Rate, 4x Channel Over Sampling Rate,

Correlation Sync., No Frame Detection,

20 Octets per PPDUs, 1e4 Monte Carlo Simulation,

Without Power Amplifier

Liang Li, WXZJ

performance comparison in multipath channel
Performance Comparison in Multipath Channel

4x Tx/Rx Over Sampling Rate, 4x Channel Over Sampling Rate,

No Sync Error, No Frame Detection,

20 Octets per PPDUS, 1e4 Monte Carlo Simulation,

Without Filter and Power Amplifier[Result]There is about 0.5dB difference between the two PER performances.

Liang Li, WXZJ

the per in multiple channel and delay condition
The PER in Multiple Channel and Delay Condition

4x Tx/Rx Over Sampling Rate, 4x Channel Over Sampling Rate,

With the practical Sync method.

20 Octets per PPDUS, 1e4 Monte Carlo Simulation, With the mentioned FIR filter (R=0.6)

for 4x over sample rate and a Power Amplifier

Liang Li, WXZJ

slide14

Summary

  • Enhanced W16 can satisfy the stated 6 criteria that will
    • Avoid spikes in frequency spectrum
    • Simplify correlation operations
    • Enable simple frequency offset and DC compensation
  • The performance is the same as the DSSS (E16)

Liang Li, WXZJ

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