1. doc.: IEEE 802.15-09-0114-00-004g-Trends-in-SUN-capacity
<month year>
Sept. 2012
Project: IEEE P Working Group for Wireless Personal Area Networks(WPANs)
Submission Title: Comments on FSK spreading sequence
Date Submitted:
Source: Mi-Kyung Oh, Jae-Hwan Kim, Jae-Young Kim and Sangsung Choi (ETRI)
Contact:
Voice: ,
Re: Call for proposals
Abstract:
Purpose: Notice: This document has been prepared to assist the IEEE P 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 P
Slide 1
ETRI
Emmanuel Monnerie, Landis+Gyr

2. Spreading Spreading Spreading sequence design
Sept. 2012
Spreading
Spreading
Selectively used for enhanced reliability
Apply to (PHR+PSDU)
Spreading gain: dependent on spreading factor
Spreading sequence design
Mainly focus on spreading gain & low complexity receiver architecture
Do not need to consider the sample-level timing synchronization since spreading sequence does not apply to preamble & SFD
PHY
Layer
Preamble
PHR
PSDU
Spreading
SFD
ETRI

3. Spreading Sequence Selection criteria
Sept. 2012
Spreading Sequence
Selection criteria
In terms of spreading gain, any spreading sequence pattern will give the same spreading gain in (PHR+PSDU) part
Due to chip-symbol level de-spreading (or correlation)
However, it is desirable that spreading sequence provides some benefits considering characteristics of FSK system
Commercially popular low-complexity FSK receivers are optimally designed for “01” or “10” repetition for CFO estimation/compensation and timing recovery
e.g.) ADF7020, CC1101
ETRI

4. Spreading Sequence In P802.15.4k/D1 draft
Sept. 2012
Spreading Sequence
In P k/D1 draft
“01” or “10” repetition sequence
Slide 4
ETRI

5. Benefits of Current Spreading Sequence
Sept. 2012
Benefits of Current Spreading Sequence
1. Symbol timing synchronization
“01” or “10” repetition sequence provides high frequency of chip-symbol transition which helps chip-symbol timing synchronization (or tracking) in general CDR (Clock & Data Recovery) block of FSK system
Key Point
“01” or “10” repetition
MR-OQPSK PHY Sequence
Chip-symbol transition
7 (SF=8)
15 (SF=16)
3~4 (SF=8)
8 (SF=16)
ETRI

6. Benefits of Current Spreading Sequence
Sept. 2012
Benefits of Current Spreading Sequence
2. CFO estimation/update
Preamble: multiples of “ ” which are best for CFO estimation for FSK system
Generally, CFO estimation is carried out during preamble reception
“01” or “10” repetition sequence enables to perform additional CFO update during PHR & PSDU reception without any additional logic at the receiver
Key Point
“01” or “10” repetition
MR-OQPSK PHY Sequence
Regular 01 pattern length
8 (SF=8)
16 (SF=16)
2 (SF=8)
4 (SF=16)
ETRI

7. Benefits of Current Spreading Sequence
Sept. 2012
Benefits of Current Spreading Sequence
3. Low-complexity de-spreading architecture
“01” or “10” repetition sequence requires the minimal implementation logic when chip-symbol level de-spreading
No sequence memory or no sequence matching is required
Repetitive “Add and Subtract” operation is enough
Scalability: De-spreading logic is independent to SF=2,4,8,16.
ETRI

8. Sept. 2012
Conclusion
The spreading sequence in P k/D1 draft is best when considering both spreading gain and low-complexity FSK receiver
ETRI