1. New Code for Symbol-to-Chip Spreading for Multiple PPDs
Month Year
doc.: IEEE yy/xxxxr0
November 2007
New Code for Symbol-to-Chip Spreading for Multiple PPDs
IEEE P Wireless RANs Date:
Authors:
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Soo-Young Chang, Huawei Technologies
John Doe, Some Company

2. Month Year
doc.: IEEE yy/xxxxr0
November 2007
Abstract
In the current TG1 draft, multiple PPDs can be operated in a region overlapping with each other. All the PPDs and other protecting devices use the same 8 bit code for symbol-to-chip spreading. It means that when each PPD sends its beacon frames continuously, the receiver of the WRAN or other protecting devices can not distinguish a signal from a PPD from signals from other PPDs.
In this document, to solve this problem an orthogonal code which has 8 orthogonal codewords is introduced. One of these codewords is assigned to a PPD and SPDs associated to this PPD. Using this orthogonality, a signal from each PPD network can be identified.
To make the system simpler, in this proposal, synchronization is executed among PPD networks although it is not necessary.
Soo-Young Chang, Huawei Technologies
John Doe, Some Company

3. PROBLEM TO BE SOLVED WRAN device PPD 1 PPD 2 PPD 3
November 2007
PROBLEM TO BE SOLVED
WRAN device
Multiple PPDs is operated in a region.
Signals from these PPDs are detected by a WRAN device (such as a CPE).
Signals can not be decoded by the WRAN device and other protecting devices if they use the same code for symbol-to-chip spreading.
How can a signal from a PPD be differentiated from signals from different PPDs?
PPD 1
PPD 2
PPD 3
Soo-Young Chang, Huawei Technologies

4. NEW CODE FOR SYMBOL-TO-CHIP SPREADING
November 2007
NEW CODE FOR SYMBOL-TO-CHIP SPREADING
Each PPD has its own orthogonal codeword for symbol-to-chip spreading.
A set of orthogonal codewords which are orthogonal to each other are used. One of codewords is assigned to each PPD.
An SPD has the same codeword as the PPD it is associated with does.
codeword 1
for PPD 1 network
codeword 2
for PPD 2 network
codeword 8
for PPD 8 network
Soo-Young Chang, Huawei Technologies

5. ORTHOGONAL 8 BIT CODE codeword index c0 c1 c2 c3 c4 c5 c6 c7 1 2 3 4 5
Month Year
doc.: IEEE yy/xxxxr0
November 2007
ORTHOGONAL 8 BIT CODE
codeword index c0 c1 c2 c3 c4 c5 c6 c7 1 2 3 4 5 6 7 8
Soo-Young Chang, Huawei Technologies
John Doe, Some Company

6. NETWORK FORMING BY A PPD
November 2007
NETWORK FORMING BY A PPD
Before it begins its operation as a PPD, a protecting device searches other networks (or PPDs) in the area.
If it finds one or more PPDs, it decides whether it will be a new PPD or not.
If it decides to be a new PPD, it selects one codeword among the 8 codewords which is not used by other PPDs for spreading.
It executes synchronization with other PPDs and forms a network.
The WRAN and other protecting devices associated can detect each PPD signals using its orthogonal codeword for symbol detection.
Soo-Young Chang, Huawei Technologies

7. November 2007
CONCLUSIONS
In the document, a code is proposed for TG1 symbol-to-chip spreading.
It is being proposed to solve the problem when multiple PPDs are operated at the same time in a region.
If multiple PPDs send their beacon signals, it will cause collisions and the WRAN can not decode these beacon signals.
With the new code design for symbol-to-chip spreading, up to 8 PPDs can be deployed in a region in a TV channel simultaneously.
For simplicity of decoding at the WRAN, it is assumed that each PPD is synchronized with other PPDs.
An SPD has the same codeword as the PPD it is associated with does.
Soo-Young Chang, Huawei Technologies

8. November 2007
References
Comment #1 submitted for the second TG1 letter ballot by Soo-Young Chang, Nov. 8, 2007
Soo-Young Chang, Huawei Technologies